技术领域Technical Field
本发明涉及发泡性甲基丙烯酸甲酯系树脂颗粒、甲基丙烯酸甲酯系树脂发泡颗粒、甲基丙烯酸甲酯系树脂发泡成型体和消失模。The present invention relates to expandable methyl methacrylate resin particles, methyl methacrylate resin foamed particles, methyl methacrylate resin foamed molded bodies and lost foams.
背景技术Background Art
在进行金属铸造时，已知将使用发泡成型体制作的模型埋入铸造砂中，将熔融金属流入该发泡成型体而将发泡成型体与金属进行置换，从而铸造铸件的消失模铸造法(整模法(full mold method))。整模法中，甲基丙烯酸甲酯系聚合物的发泡成型体作为消失模被广泛使用。When performing metal casting, it is known that a model made of a foamed molded body is buried in casting sand, molten metal is poured into the foamed molded body to replace the foamed molded body with the metal, thereby casting a casting in a lost foam casting method (full mold method). In the full mold method, a foamed molded body of a methyl methacrylate polymer is widely used as a lost foam.
作为用于制造甲基丙烯酸甲酯系聚合物的发泡成型体的发泡性甲基丙烯酸甲酯系树脂颗粒，例如，专利文献1中公开了一种发泡性甲基丙烯酸甲酯系树脂颗粒，其包含基材树脂与发泡剂，该基材树脂包含甲基丙烯酸甲酯单元、丙烯酸酯单元及源自交联剂的结构单元作为结构单元。As expandable methyl methacrylate resin particles for producing a foamed molded article of a methyl methacrylate polymer, for example, Patent Document 1 discloses expandable methyl methacrylate resin particles comprising a base resin and a foaming agent, wherein the base resin comprises, as structural units, a methyl methacrylate unit, an acrylate unit, and a structural unit derived from a crosslinking agent.
现有技术文献Prior art literature
专利文献Patent Literature
专利文献1：WO2021/199878号公报Patent Document 1: WO2021/199878
发明内容Summary of the invention
发明要解决的问题Problem that the invention aims to solve
然而，出于甲基丙烯酸甲酯系树脂发泡成型体的表面美观性的观点，上述那样的现有技术存在改善的余地。However, from the viewpoint of the surface aesthetics of the methyl methacrylate-based resin foam-molded product, the above-mentioned conventional techniques have room for improvement.
本发明的一个方式在于提供一种发泡性甲基丙烯酸甲酯系树脂颗粒，其能够提供表面美观性优异的甲基丙烯酸甲酯系树脂发泡成型体。One aspect of the present invention is to provide expandable methyl methacrylate resin particles capable of providing a methyl methacrylate resin foamed molded product having excellent surface appearance.
用于解决问题的方案Solutions for solving problems
发明人等为了解决前述课题而进行了深入研究，结果完成了本发明。即，本发明的一个实施方式包括以下的构成。The inventors have conducted intensive studies to solve the above problems and have completed the present invention. That is, one embodiment of the present invention includes the following configurations.
一种发泡性甲基丙烯酸甲酯系树脂颗粒，其包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，使前述发泡性甲基丙烯酸甲酯系树脂颗粒在蒸气吹入压为0.10MPa～0.16MPa、且发泡机内压为0.005MPa～0.030MPa的条件下发泡时，直至前述发泡性甲基丙烯酸甲酯系树脂颗粒成为体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒为止的时间(A)小于80秒。A foamable methyl methacrylate resin particle comprising a base resin and a foaming agent, wherein the base resin comprises a methyl methacrylate unit and an acrylate unit as structural units, the volume average particle diameter of the foamable methyl methacrylate resin particle is 0.30 mm to 0.50 mm, and the peak top particle diameter of the particle size distribution is 0.33 mm to 0.47 mm, and when the foamable methyl methacrylate resin particle is foamed under the conditions of a steam blowing pressure of 0.10 MPa to 0.16 MPa and an internal pressure of a foaming machine of 0.005 MPa to 0.030 MPa, the time (A) until the foamable methyl methacrylate resin particle becomes a methyl methacrylate resin foamed particle having a volume ratio of 50 times is less than 80 seconds.
一种发泡性甲基丙烯酸甲酯系树脂颗粒，其包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述丙烯酸酯单元为丙烯酸丁酯单元，在将前述基材树脂中的前述甲基丙烯酸甲酯单元及前述丙烯酸丁酯单元的总计含量设为100重量份的情况下，前述甲基丙烯酸甲酯单元的含量为93.0重量份～98.0重量份，前述丙烯酸丁酯单元的含量为2.0重量份～7.0重量份，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，前述基材树脂的重均分子量为17.5万～28.5万。A foamable methyl methacrylate resin particle comprises a base resin and a foaming agent, wherein the base resin comprises a methyl methacrylate unit and an acrylate unit as structural units, the acrylate unit is a butyl acrylate unit, and when the total content of the methyl methacrylate unit and the butyl acrylate unit in the base resin is 100 parts by weight, the content of the methyl methacrylate unit is 93.0 parts by weight to 98.0 parts by weight, and the content of the butyl acrylate unit is 2.0 parts by weight to 7.0 parts by weight, the volume average particle size of the foamable methyl methacrylate resin particle is 0.30 mm to 0.50 mm, and the peak particle size of the particle size distribution is 0.33 mm to 0.47 mm, and the weight average molecular weight of the base resin is 175,000 to 285,000.
发明的效果Effects of the Invention
根据本发明的一个方式，产生如下效果：能够提供一种发泡性甲基丙烯酸甲酯系树脂颗粒，前述发泡性甲基丙烯酸甲酯系树脂颗粒能够提供表面美观性优异的甲基丙烯酸甲酯系树脂发泡成型体。According to one embodiment of the present invention, there is provided an effect of being able to provide expandable methyl methacrylate resin particles capable of providing a methyl methacrylate resin foamed molded product having excellent surface appearance.
具体实施方式DETAILED DESCRIPTION
以下对本发明的一个实施方式进行说明，但本发明不受其限定。本发明不受到以下说明的各构成的限定，可以在权利要求书所示的范围内进行多种变更。另外，将不同的实施方式或实施例中分别公开的技术手段进行组合而得到的实施方式或实施例也包含在本发明的技术范围内。进而，通过将各实施方式中公开的技术手段进行组合，可以形成新的技术特征。需要说明的是，本说明书中记载的所有学术文献和专利文献均作为参考文献而援引入本说明书中。另外，只要本说明书中没有特别记载，表示数值范围的“A～B”就指的是“A以上(包含A且大于A)且B以下(包含B且小于B)”。An embodiment of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited by the various structures described below, and various changes can be made within the scope indicated in the claims. In addition, embodiments or embodiments obtained by combining the technical means respectively disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, by combining the technical means disclosed in each embodiment, new technical features can be formed. It should be noted that all academic literature and patent documents recorded in this specification are cited as references in this specification. In addition, as long as there is no special description in this specification, "A~B" indicating a numerical range means "above A (including A and greater than A) and below B (including B and less than B)".
本说明书中，有时将“发泡性甲基丙烯酸甲酯系树脂颗粒”也称为“发泡性树脂颗粒”，将“甲基丙烯酸甲酯系树脂发泡颗粒”也称为“发泡颗粒”，将“甲基丙烯酸甲酯系树脂发泡成型体”也称为“发泡成型体”。In this specification, “expandable methyl methacrylate resin particles” may also be referred to as “expandable resin particles”, “methyl methacrylate resin foamed particles” may also be referred to as “foamed particles”, and “methyl methacrylate resin foamed molded article” may also be referred to as “foamed molded article”.
〔1.本发明的一个实施方式的技术构思〕[1. Technical concept of one embodiment of the present invention]
出于表面美观性的观点，使用专利文献1中公开的发泡性树脂颗粒而得到的发泡成型体存在改善的余地。From the viewpoint of surface aesthetics, the foamed molded product obtained using the expandable resin particles disclosed in Patent Document 1 has room for improvement.
本发明人等进行了深入研究，结果独立地发现了以下的新事项，从而完成了本发明：(i)粒度分布的峰顶粒径在特定范围内的发泡性甲基丙烯酸甲酯系树脂颗粒的粒径的大小不均较小，即，均一性优异，(ii)具有特定量的特定结构单元、且基材树脂的重均分子量小的发泡性甲基丙烯酸甲酯系树脂颗粒的发泡性优异，(ii)使体积平均粒径小的发泡性甲基丙烯酸甲酯系树脂颗粒进行发泡而成的甲基丙烯酸甲酯系树脂发泡颗粒，对各种形状的模具物(例如，宽度为数mm左右的窄处)的填充性优异，(iii)对于使均匀性及发泡性优异、且体积平均粒径小的发泡性甲基丙烯酸甲酯系树脂颗粒进行发泡而成的甲基丙烯酸甲酯系树脂发泡颗粒，在使用该甲基丙烯酸甲酯系树脂发泡颗粒的模内成型中，成型中途的甲基丙烯酸甲酯系树脂发泡成型体的表面扩展，因此得到的甲基丙烯酸甲酯系树脂发泡成型体的表面美观性改善。The present inventors have made intensive studies and, as a result, have independently discovered the following new matters, thereby completing the present invention: (i) expandable methyl methacrylate resin particles having a peak top particle size in a specific range of particle size distribution have small variations in particle size, i.e., excellent uniformity; (ii) expandable methyl methacrylate resin particles having a specific amount of specific structural units and a base resin having a small weight average molecular weight have excellent expandability; (iii) expandable methyl methacrylate resin particles obtained by expanding expandable methyl methacrylate resin particles having a small volume average particle size have excellent filling properties into molds of various shapes (e.g., narrow portions having a width of about several mm); (iv) expandable methyl methacrylate resin particles obtained by expanding expandable methyl methacrylate resin particles having excellent uniformity and expandability and a small volume average particle size, and, in in-mold molding using the expandable methyl methacrylate resin particles, the surface of the methyl methacrylate resin foam molded article during molding is expanded, thereby improving the surface aesthetics of the obtained methyl methacrylate resin foam molded article.
甲基丙烯酸甲酯系树脂发泡颗粒的填充性差时，将该甲基丙烯酸甲酯系树脂发泡颗粒填充至模具物内时，在模具物内形成该发泡颗粒的填充密度高的区域和该发泡颗粒的填充密度低的区域。若在这样的状态下实施模内成型，则在发泡颗粒的填充密度低的区域中，相比于发泡颗粒的填充密度高的区域，为了填补间隙而需要发泡颗粒发泡得更大。即，发泡颗粒的填充密度低的区域和发泡颗粒的填充密度高的区域中，发泡颗粒的发泡程度(换言之，构成甲基丙烯酸甲酯系树脂发泡成型体的发泡颗粒的尺寸)不同，因此得到的甲基丙烯酸甲酯系树脂发泡成型体的表面美观性降低。因此，如后述的实施例记载的那样，“甲基丙烯酸甲酯系树脂发泡颗粒的填充性”可以成为用于评价甲基丙烯酸甲酯系树脂发泡成型体的表面美观性的指标之一。When the filling property of methyl methacrylate resin foamed particles is poor, when the methyl methacrylate resin foamed particles are filled into the mold object, the region with high packing density of the foamed particles and the region with low packing density of the foamed particles are formed in the mold object. If in-mold molding is implemented under such a state, in the region with low packing density of the foamed particles, compared with the region with high packing density of the foamed particles, the foamed particles need to be foamed larger in order to fill the gap. That is, in the region with low packing density of the foamed particles and the region with high packing density of the foamed particles, the foaming degree of the foamed particles (in other words, the size of the foamed particles constituting the methyl methacrylate resin foamed molded body) is different, so the surface aesthetics of the methyl methacrylate resin foamed molded body obtained is reduced. Therefore, as described in the embodiment described later, "the filling property of methyl methacrylate resin foamed particles" can be one of the indicators for evaluating the surface aesthetics of the methyl methacrylate resin foamed molded body.
发泡性甲基丙烯酸甲酯系树脂颗粒的峰顶粒径大时，粒径的大小不均较大，源自该发泡性甲基丙烯酸甲酯系树脂颗粒的甲基丙烯酸甲酯系树脂发泡颗粒的粒径的大小不均也变大。若使用粒径的大小不均较大的甲基丙烯酸甲酯系树脂发泡颗粒实施模内成型，则构成得到的甲基丙烯酸甲酯系树脂发泡成型体的发泡颗粒的尺寸不同，因此该甲基丙烯酸甲酯系树脂发泡成型体的表面美观性降低。因此，如后述的实施例记载的那样，“发泡性甲基丙烯酸甲酯系树脂颗粒的峰顶粒径”可以成为用于评价甲基丙烯酸甲酯系树脂发泡成型体的表面美观性的指标之一。When the peak particle size of the foamable methyl methacrylate resin particles is large, the size unevenness of the particle size is large, and the size unevenness of the particle size of the methyl methacrylate resin foamed particles derived from the foamable methyl methacrylate resin particles also becomes larger. If the methyl methacrylate resin foamed particles with large size unevenness of the particle size are used to implement in-mold molding, the sizes of the foamed particles constituting the obtained methyl methacrylate resin foamed molded body are different, so the surface aesthetics of the methyl methacrylate resin foamed molded body is reduced. Therefore, as described in the examples described later, the "peak particle size of the foamable methyl methacrylate resin particles" can be one of the indicators for evaluating the surface aesthetics of the methyl methacrylate resin foamed molded body.
〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕[2. Foamable methyl methacrylate resin particles]
本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，在蒸气吹入压0.10MPa～0.16MPa、且发泡机内压力0.005MPa～0.030MPa的条件下使前述发泡性甲基丙烯酸甲酯系树脂颗粒发泡时，直至前述发泡性甲基丙烯酸甲酯系树脂颗粒成为体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒为止的时间(A)小于80秒。The expandable methyl methacrylate resin particles according to one embodiment of the present invention include a base resin and a foaming agent, wherein the base resin includes a methyl methacrylate unit and an acrylate unit as structural units, the volume average particle size of the expandable methyl methacrylate resin particles is 0.30 mm to 0.50 mm, and the peak top particle size of the particle size distribution is 0.33 mm to 0.47 mm, and when the expandable methyl methacrylate resin particles are expanded under the conditions of a steam blowing pressure of 0.10 MPa to 0.16 MPa and a pressure in a foaming machine of 0.005 MPa to 0.030 MPa, the time (A) until the expandable methyl methacrylate resin particles become methyl methacrylate resin foamed particles having a volume ratio of 50 times is less than 80 seconds.
本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述丙烯酸酯单元为丙烯酸丁酯单元，在将前述基材树脂中的前述甲基丙烯酸甲酯单元及前述丙烯酸丁酯单元的总计含量设为100重量份的情况下，前述甲基丙烯酸甲酯单元的含量为93.0重量份～98.0重量份，前述丙烯酸丁酯单元的含量为2.0重量份～7.0重量份，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，前述基材树脂的重均分子量为17.5万～28.5万。The expandable methyl methacrylate resin particles according to one embodiment of the present invention include a base resin and a foaming agent, wherein the base resin includes a methyl methacrylate unit and an acrylate unit as structural units, the acrylate unit is a butyl acrylate unit, and when the total content of the methyl methacrylate unit and the butyl acrylate unit in the base resin is 100 parts by weight, the content of the methyl methacrylate unit is 93.0 parts by weight to 98.0 parts by weight, and the content of the butyl acrylate unit is 2.0 parts by weight to 7.0 parts by weight. The volume average particle size of the expandable methyl methacrylate resin particles is 0.30 mm to 0.50 mm, and the peak particle size of the particle size distribution is 0.33 mm to 0.47 mm. The weight average molecular weight of the base resin is 175,000 to 285,000.
以下，有时也将“本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒”称为“本发泡性树脂颗粒”。Hereinafter, “expandable methyl methacrylate resin particles according to one embodiment of the present invention” may also be referred to as “present expandable resin particles”.
通过利用公知的方法对本发泡性树脂颗粒进行发泡，能够提供发泡颗粒。通过利用公知的方法对使本发泡性树脂颗粒进行发泡而成的发泡颗粒进行模内成型，能够提供发泡成型体。The present expandable resin particles can be expanded by a known method to provide expandable particles, and the expandable resin particles can be in-mold molded by a known method to provide a foamed molded article.
本发泡性树脂颗粒具有上述构成，因此具有能够提供表面美观性优异的甲基丙烯酸甲酯系树脂发泡成型体的优点。具体而言，本发泡性树脂颗粒的粒度分布的峰顶粒径在特定的范围内。因此，本发泡性树脂颗粒具有粒径的大小不均较小、即均匀性优异的优点。另外，本发明的一个实施方式的发泡性树脂颗粒的发泡性优异。另外，本发明的另一个实施方式的发泡性树脂颗粒具有特定量的特定结构单元、且基材树脂的重均分子量小，因此令人惊讶的是，发泡性优异。另外，由于本发泡性树脂颗粒的体积平均粒径小，因此使该发泡性树脂颗粒进行发泡而成的发泡颗粒也具有粒径小的优点。粒径小的发泡颗粒具有对各种形状的模具物(例如，宽度为数mm左右的狭处)的填充性优异的优点。另外，对于使均匀性和发泡性优异、且体积平均粒径小的发泡性树脂颗粒进行发泡而成的发泡颗粒，在使用该发泡颗粒的模内成型中，成型中途的甲基丙烯酸甲酯系树脂发泡成型体的表面扩展，结果具有能够提供表面美观性优异的发泡成型体的优点。The present foamable resin particles have the above-mentioned structure, and therefore have the advantage of being able to provide a methyl methacrylate resin foamed molded body with excellent surface aesthetics. Specifically, the peak particle size of the particle size distribution of the present foamable resin particles is within a specific range. Therefore, the present foamable resin particles have the advantage of having a small uneven particle size, that is, excellent uniformity. In addition, the foamable resin particles of one embodiment of the present invention are excellent in foamability. In addition, the foamable resin particles of another embodiment of the present invention have a specific amount of specific structural units, and the weight average molecular weight of the substrate resin is small, so surprisingly, the foamable properties are excellent. In addition, since the volume average particle size of the present foamable resin particles is small, the foamable particles formed by foaming the foamable resin particles also have the advantage of a small particle size. Foamable particles with a small particle size have the advantage of excellent filling properties for mold objects of various shapes (for example, a narrow place with a width of about several mm). In addition, in the case of foamed particles obtained by foaming foamable resin particles having excellent uniformity and foamability and a small volume average particle size, in the in-mold molding using the foamed particles, the surface of the methyl methacrylate resin foamed molded product is expanded during the molding process, resulting in an advantage of being able to provide a foamed molded product with excellent surface aesthetics.
(基材树脂)(Base resin)
本发泡性树脂颗粒包含的基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元。本说明书中，“甲基丙烯酸甲酯单元”是指源自甲基丙烯酸甲酯单体的结构单元，“丙烯酸酯单元”是指源自丙烯酸酯单体的结构单元。本说明书中，有时会省略“单体”的标记。因此，本说明书中例如仅标记为“甲基丙烯酸甲酯”和“丙烯酸酯”时，分别指“甲基丙烯酸甲酯单体”和“丙烯酸酯单体”。The base resin contained in the present foamable resin particles contains methyl methacrylate units and acrylate units as structural units. In this specification, "methyl methacrylate unit" refers to a structural unit derived from a methyl methacrylate monomer, and "acrylate unit" refers to a structural unit derived from an acrylate monomer. In this specification, the mark of "monomer" is sometimes omitted. Therefore, in this specification, for example, when only "methyl methacrylate" and "acrylate" are marked, they refer to "methyl methacrylate monomer" and "acrylate monomer", respectively.
本发泡性树脂颗粒包含的基材树脂中，相对于甲基丙烯酸甲酯单元及丙烯酸酯单元的总量100重量份，可以为(a)甲基丙烯酸甲酯单元的含量为93.0重量份～98.0重量份、且丙烯酸酯单元的含量为2.0重量份～7.0重量份，优选为(b)甲基丙烯酸甲酯单元的含量为93.5重量份～98.0重量份、且丙烯酸酯单元的含量为2.0重量份～6.5重量份，更优选为(c)甲基丙烯酸甲酯单元的含量为94.0重量份～98.0重量份、且丙烯酸酯单元的含量为2.0重量份～6.0重量份，进一步优选为(d)甲基丙烯酸甲酯单元的含量为94.5重量份～98.0重量份、且丙烯酸酯单元的含量为2.0重量份～5.5重量份，特别优选为(e)甲基丙烯酸甲酯单元的含量为95.0重量份～97.5重量份、且丙烯酸酯单元的含量为2.5重量份～5.0重量份。In the base resin contained in the present expandable resin particles, the content of the methyl methacrylate unit can be (a) 93.0 to 98.0 parts by weight and the content of the acrylate unit can be 2.0 to 7.0 parts by weight, preferably (b) 93.5 to 98.0 parts by weight and the content of the acrylate unit can be 2.0 to 6.5 parts by weight, and more preferably (c) 93.5 to 98.0 parts by weight and the content of the acrylate unit can be 2.0 to 6.5 parts by weight, relative to 100 parts by weight of the total amount of the methyl methacrylate unit and the acrylate unit. The content of the methyl acrylate unit is 94.0 to 98.0 parts by weight, and the content of the acrylate unit is 2.0 to 6.0 parts by weight. (d) The content of the methyl methacrylate unit is more preferably 94.5 to 98.0 parts by weight, and the content of the acrylate unit is 2.0 to 5.5 parts by weight. (e) The content of the methyl methacrylate unit is particularly preferably 95.0 to 97.5 parts by weight, and the content of the acrylate unit is 2.5 to 5.0 parts by weight.
基材树脂中，相对于甲基丙烯酸甲酯单元及丙烯酸酯单元的总量100重量份，丙烯酸酯单元的含量在上述范围内时，发泡性树脂颗粒具有发泡性优异的优点。结果，发泡性树脂颗粒(发泡颗粒)具有能够提供表面美观性优异的发泡成型体的优点。In the base resin, when the content of the acrylate unit is within the above range relative to 100 parts by weight of the total amount of the methyl methacrylate unit and the acrylate unit, the foamable resin particles have the advantage of excellent foamability. As a result, the foamable resin particles (foamable particles) have the advantage of being able to provide a foamed molded body with excellent surface aesthetics.
作为本发明的一个实施方式的丙烯酸酯，可以列举丙烯酸甲酯、丙烯酸乙酯、丙烯酸丙酯、丙烯酸丁酯等。作为丙烯酸酯，特别优选为丙烯酸丁酯。换言之，丙烯酸酯单元特别优选为源自丙烯酸丁酯单体的丙烯酸丁酯单元。丙烯酸丁酯使基材树脂的玻璃化转变温度降低的效果大。因此，根据该构成，发泡性树脂颗粒具有发泡性优异的优点。结果，发泡性树脂颗粒(发泡颗粒)具有能够提供表面美观性优异的发泡成型体的优点。As an acrylate of one embodiment of the present invention, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, etc. can be cited. As the acrylate, butyl acrylate is particularly preferred. In other words, the acrylate unit is particularly preferably a butyl acrylate unit derived from a butyl acrylate monomer. Butyl acrylate has a great effect of lowering the glass transition temperature of the substrate resin. Therefore, according to this structure, the foamable resin particles have the advantage of excellent foamability. As a result, the foamable resin particles (foaming particles) have the advantage of being able to provide a foamed molded body with excellent surface aesthetics.
本发泡性树脂颗粒的基材树脂可以包含源自交联剂的结构单元(以下也称为交联剂单元)。本发泡性树脂颗粒的基材树脂包含交联剂单元时，该发泡性树脂颗粒具有能够提供收缩抑制性优异的发泡颗粒、且发泡性优异的优点。The base resin of the present expandable resin particles may contain a structural unit derived from a crosslinking agent (hereinafter also referred to as a crosslinking agent unit). When the base resin of the present expandable resin particles contains a crosslinking agent unit, the expandable resin particles have the advantages of being able to provide expandable particles with excellent shrinkage suppression and excellent expandability.
作为交联剂，例如可以列举具有2个以上示出自由基反应性的官能团的化合物。具有2个以上显示自由基反应性的官能团的化合物之中，作为交联剂，优选使用具有2个官能团的二官能性单体。换言之，本发泡性树脂颗粒的基材树脂优选包含源自二官能性单体的结构单元即二官能性单体单元作为交联剂单元。根据该构成，具有如下优点：(a)发泡性树脂颗粒的发泡性更优异，(b)使该发泡性树脂颗粒进行发泡而成的发泡颗粒的收缩抑制性更优异，并且(c)使该发泡颗粒模内成型而成的发泡成型体的表面美观性优异。As a crosslinking agent, for example, a compound having two or more functional groups showing free radical reactivity can be cited. Among the compounds having two or more functional groups showing free radical reactivity, as a crosslinking agent, a difunctional monomer having two functional groups is preferably used. In other words, the base resin of the present foamable resin particles preferably contains a structural unit derived from a difunctional monomer, i.e., a difunctional monomer unit as a crosslinking agent unit. According to this structure, there are the following advantages: (a) the foamability of the foamable resin particles is better, (b) the shrinkage inhibition of the foamed particles formed by foaming the foamable resin particles is better, and (c) the surface aesthetics of the foamed molded body formed by in-mold molding of the foamed particles is excellent.
作为二官能性单体，例如可以列举：(a)乙二醇二(甲基)丙烯酸酯、二乙二醇二(甲基)丙烯酸酯、三乙二醇二(甲基)丙烯酸酯等将乙二醇的两末端羟基利用(甲基)丙烯酸进行酯化而成的化合物、和/或将该乙二醇的低聚物的两末端羟基利用(甲基)丙烯酸进行酯化而成的化合物、(b)新戊二醇二(甲基)丙烯酸酯、己二醇二(甲基)丙烯酸酯(例如1,6-己二醇二丙烯酸酯等)、丁二醇二(甲基)丙烯酸酯等将二元醇的羟基利用丙烯酸或甲基丙烯酸进行酯化而成的化合物、以及(c)二乙烯基苯等具有2个烯基的芳基化合物等。己二醇二(甲基)丙烯酸酯容易调整基材树脂的分子量，因此优选1,6-己二醇二丙烯酸酯等己二醇二(甲基)丙烯酸酯作为二官能性单体。本说明书中，“(甲基)丙烯酸酯”是指甲基丙烯酸酯和/或丙烯酸酯，“(甲基)丙烯酸”是指甲基丙烯酸和/或丙烯酸。Examples of the bifunctional monomer include: (a) compounds obtained by esterifying both terminal hydroxyl groups of ethylene glycol with (meth)acrylic acid, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate, and/or compounds obtained by esterifying both terminal hydroxyl groups of the ethylene glycol oligomer with (meth)acrylic acid, (b) compounds obtained by esterifying the hydroxyl groups of diols with acrylic acid or methacrylic acid, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate (e.g., 1,6-hexanediol diacrylate, etc.), and butanediol di(meth)acrylate, and (c) aromatic compounds having two alkenyl groups, such as divinylbenzene, etc. Hexanediol di(meth)acrylate is easy to adjust the molecular weight of the base resin, so hexanediol di(meth)acrylates such as 1,6-hexanediol diacrylate are preferred as bifunctional monomers. In the present specification, "(meth)acrylate" means methacrylate and/or acrylate, and "(meth)acrylic acid" means methacrylic acid and/or acrylic acid.
基材树脂中，相对于甲基丙烯酸甲酯单元及丙烯酸酯单元的总计量100重量份，交联剂单元的含量为0重量份以上且小于0.20重量份，优选为0重量份～0.19重量份，更优选为0重量份～0.17重量份以下，更优选为0重量份～0.15重量份以下，进一步优选为0重量份～0.13重量份。根据前述构成，具有如下优点：(a)发泡性树脂颗粒的发泡性优异、(b)使该发泡性树脂颗粒进行发泡而成的发泡颗粒的收缩抑制性优异、(c)使该发泡颗粒进行模内成型而成的发泡成型体的表面美观性优异。基材树脂中，相对于甲基丙烯酸甲酯单元及丙烯酸酯单元的总量100重量份，交联剂单元的含量可以为0.01重量份以上，可以为0.03重量份以上，可以为0.05重量份以上，也可以为0.08重量份以上。In the base resin, the content of the crosslinking agent unit is 0 part by weight or more and less than 0.20 part by weight, preferably 0 to 0.19 part by weight, more preferably 0 to 0.17 part by weight or less, more preferably 0 to 0.15 part by weight or less, and further preferably 0 to 0.13 part by weight, relative to 100 parts by weight of the total amount of the methyl methacrylate unit and the acrylate unit. According to the above-mentioned structure, there are the following advantages: (a) the foaming property of the foamable resin particles is excellent, (b) the shrinkage inhibition property of the foamed particles formed by foaming the foamable resin particles is excellent, and (c) the surface aesthetics of the foamed molded body formed by in-mold molding of the foamed particles is excellent. In the base resin, the content of the crosslinking agent unit can be 0.01 part by weight or more, 0.03 part by weight or more, 0.05 part by weight or more, or 0.08 part by weight or more, relative to 100 parts by weight of the total amount of the methyl methacrylate unit and the acrylate unit.
本发泡性树脂颗粒的基材树脂可以进一步含有源自芳香族系单体的结构单元(以下也称为芳香族系单元)作为结构单元。作为芳香族系单体，可以列举苯乙烯、α-甲基苯乙烯、对甲基苯乙烯、叔丁基苯乙烯及氯苯乙烯等芳香族乙烯基化合物等。本发泡性树脂颗粒的基材树脂包含芳香族系单元时，能够得到强度优异的发泡成型体。The base resin of the present foamable resin particles may further contain a structural unit derived from an aromatic monomer (hereinafter also referred to as an aromatic unit) as a structural unit. As aromatic monomers, aromatic vinyl compounds such as styrene, α-methylstyrene, p-methylstyrene, tert-butylstyrene and chlorostyrene can be listed. When the base resin of the present foamable resin particles contains an aromatic unit, a foamed molded body with excellent strength can be obtained.
另一方面，出于得到燃烧时残渣少的发泡成型体的观点，发泡性树脂颗粒的基材树脂中包含的、源自芳香族系单体的结构(例如芳香环)的量优选为尽可能少。例如，发泡性树脂颗粒的基材树脂包含的芳香族系单元的量相对于基材树脂100重量份为2.5重量份以下，优选为小于2.5重量份，更优选为2.0重量份以下，更优选为1.5重量份以下，进一步优选为1.0重量份以下，进一步优选为0.5重量份以下，特别优选为0重量份。即，本发泡性树脂颗粒的基材树脂特别优选不含有芳香族系单元。On the other hand, from the viewpoint of obtaining a foaming molded body with less residue during combustion, the amount of the structure (e.g., aromatic ring) contained in the base resin of the foamable resin particles and derived from the aromatic monomer is preferably as small as possible. For example, the amount of the aromatic unit contained in the base resin of the foamable resin particles is less than 2.5 parts by weight relative to 100 parts by weight of the base resin, preferably less than 2.5 parts by weight, more preferably less than 2.0 parts by weight, more preferably less than 1.5 parts by weight, further preferably less than 1.0 parts by weight, further preferably less than 0.5 parts by weight, and particularly preferably 0 parts by weight. That is, the base resin of the present foamable resin particles is particularly preferably free of aromatic units.
(发泡剂)(foaming agent)
本发泡性树脂颗粒中包含的发泡剂没有特别限定。作为发泡剂，例如可以列举(a)丙烷、异丁烷、正丁烷、异戊烷、正戊烷、新戊烷等作为碳原子数3以上且5以下的烃的脂肪族烃类、以及(b)二氟乙烷、四氟乙烷等臭氧破坏系数为零的氢氟碳类等挥发性发泡剂。这些发泡剂可以单独使用1种，也可以组合使用2种以上。The foaming agent contained in the foamable resin particles is not particularly limited. Examples of the foaming agent include (a) aliphatic hydrocarbons having a carbon number of 3 or more and 5 or less, such as propane, isobutane, n-butane, isopentane, n-pentane, and neopentane, and (b) volatile foaming agents such as hydrofluorocarbons having an ozone depletion coefficient of zero, such as difluoroethane and tetrafluoroethane. These foaming agents may be used alone or in combination of two or more.
本发泡性树脂颗粒中，相对于基材树脂100重量份，发泡剂的含量优选为5重量份～12重量份，更优选为7重量份～10重量份。根据该构成，有能够提供具有充分的发泡性的发泡性树脂颗粒、且不需要厚重的聚合设备的优点。In the present expandable resin particles, the content of the foaming agent is preferably 5 to 12 parts by weight, more preferably 7 to 10 parts by weight, relative to 100 parts by weight of the base resin. According to this configuration, there is an advantage that expandable resin particles having sufficient expandability can be provided without requiring heavy polymerization equipment.
(其他添加剂)(Other additives)
本发泡性树脂颗粒除基材树脂与发泡剂以外，还可以任意包含其它添加剂。作为上述其它添加剂，可以列举溶剂、增塑剂、整泡剂、阻燃剂、阻燃助剂、热射线辐射抑制剂、颜料、染料和抗静电剂等。The foamable resin particles may contain any other additives in addition to the base resin and the foaming agent. Examples of the other additives include solvents, plasticizers, foam stabilizers, flame retardants, flame retardant aids, heat ray radiation inhibitors, pigments, dyes, and antistatic agents.
作为溶剂，没有特别限定，优选为沸点50℃以上的溶剂。作为沸点50℃以上的溶剂，例如可以列举：(a)甲苯、己烷、庚烷等碳原子数6以上(C6以上)的脂肪族烃，及(b)环己烷、环辛烷等C6以上的脂环族烃等。出于能够得到发泡性优异的发泡性树脂颗粒的观点，作为沸点50℃以上的溶剂，优选为甲苯和/或环己烷。本发泡性树脂颗粒中，相对于基材树脂100重量份，溶剂的含量优选为1.5重量份～3.0重量份。溶剂相对于基材树脂100重量份的含量为(a)1.5重量份以上时，可以得到具有充分的发泡力的发泡性树脂颗粒，为(b)3.0重量份以下时，可以得到表面的膨胀得到抑制、即尺寸稳定性优异的发泡成型体。The solvent is not particularly limited, but preferably a solvent having a boiling point of 50°C or higher. Examples of solvents having a boiling point of 50°C or higher include: (a) aliphatic hydrocarbons having 6 or more carbon atoms (C6 or higher) such as toluene, hexane, and heptane, and (b) alicyclic hydrocarbons having C6 or higher such as cyclohexane and cyclooctane. From the viewpoint of obtaining foamable resin particles having excellent foamability, toluene and/or cyclohexane are preferred as solvents having a boiling point of 50°C or higher. In the present foamable resin particles, the content of the solvent is preferably 1.5 to 3.0 parts by weight relative to 100 parts by weight of the base resin. When the content of the solvent relative to 100 parts by weight of the base resin is (a) 1.5 parts by weight or higher, foamable resin particles having sufficient foaming power can be obtained, and when it is (b) 3.0 parts by weight or less, a foamed molded body having suppressed surface expansion, i.e., excellent dimensional stability can be obtained.
作为增塑剂，没有特别限定，优选为沸点200℃以上的高沸点增塑剂。作为前述高沸点增塑剂，例如可以列举：(a)硬脂酸甘油三酯、棕榈酸甘油三酯、月桂酸甘油三酯、硬脂酸二甘油酯、硬脂酸单甘油酯等脂肪酸甘油酯，(b)椰子油、棕榈油、棕榈仁油等植物油，(c)己二酸二辛酯、癸二酸二丁酯等脂肪族酯，以及(d)液体石蜡、环己烷等有机烃等。The plasticizer is not particularly limited, but is preferably a high boiling point plasticizer having a boiling point of 200° C. or higher. Examples of the high boiling point plasticizer include: (a) fatty acid glycerides such as stearic acid triglyceride, palmitic acid triglyceride, lauric acid triglyceride, stearic acid diglyceride, and stearic acid monoglyceride; (b) vegetable oils such as coconut oil, palm oil, and palm kernel oil; (c) aliphatic esters such as dioctyl adipate and dibutyl sebacate; and (d) organic hydrocarbons such as liquid paraffin and cyclohexane.
本发泡性树脂颗粒中，相对于基材树脂100重量份，增塑剂的含量优选为0.40重量份～4.00重量份，优选为0.50重量份～3.50重量份，更优选为0.60重量份～3.00重量份，更优选为0.70重量份～2.70重量份，更优选为0.80重量份～2.40重量份，更优选为0.90重量份～2.10重量份，进一步优选为1.00重量份～1.80重量份，特别优选为1.20重量份～1.50重量份。根据该构成，具有如下优点：发泡性树脂颗粒的发泡性优异，该发泡性树脂颗粒能够提供收缩抑制性优异的发泡颗粒。In the present expandable resin particles, the content of the plasticizer is preferably 0.40 to 4.00 parts by weight, preferably 0.50 to 3.50 parts by weight, more preferably 0.60 to 3.00 parts by weight, more preferably 0.70 to 2.70 parts by weight, more preferably 0.80 to 2.40 parts by weight, more preferably 0.90 to 2.10 parts by weight, further preferably 1.00 to 1.80 parts by weight, and particularly preferably 1.20 to 1.50 parts by weight, relative to 100 parts by weight of the base resin. According to this configuration, there are the following advantages: the expandable resin particles are excellent in expandability, and the expandable resin particles can provide expandable particles with excellent shrinkage suppression.
作为整泡剂，例如可以列举(a)亚甲基双硬脂酸酰胺、亚乙基双硬脂酸酰胺等脂肪族双酰胺、以及(b)聚乙烯蜡等。相对于基材树脂100重量份，整泡剂的含量优选为0.01重量份～0.50重量份。Examples of the foam stabilizer include (a) aliphatic bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide, and (b) polyethylene wax, etc. The content of the foam stabilizer is preferably 0.01 to 0.50 parts by weight based on 100 parts by weight of the base resin.
(体积平均粒径)(Volume average particle size)
本发泡性树脂颗粒的体积平均粒径为0.30mm～0.50mm，优选为0.35～0.45mm，更优选为0.40mm～0.45mm。发泡性树脂颗粒的体积平均粒径小于0.30mm时，发泡性树脂颗粒有导致发泡时的发泡性降低和/或发泡时的粘连量增加的倾向。发泡性树脂颗粒的体积平均粒径大于0.50mm时，对于将发泡性树脂颗粒进行发泡而成的发泡颗粒，将该发泡颗粒填充至成型机时，对狭窄空间的填充性变差。需要说明的是，成型机中的狭窄空间对应于得到的发泡成型体中的厚度薄的部位。本说明书中，发泡性树脂颗粒的体积平均粒径是指：使用粒度分析计(例如图像处理方式Millitrac JPA粒度分析计)，以体积基准测定发泡性树脂颗粒的粒径，通过累积分布表示得到的结果，将体积累积成为50％的粒径(即D50)作为体积平均粒径。The volume average particle size of the foamable resin particles is 0.30 mm to 0.50 mm, preferably 0.35 to 0.45 mm, and more preferably 0.40 mm to 0.45 mm. When the volume average particle size of the foamable resin particles is less than 0.30 mm, the foamable resin particles tend to cause a decrease in foamability during foaming and/or an increase in the amount of adhesion during foaming. When the volume average particle size of the foamable resin particles is greater than 0.50 mm, when the foamable particles obtained by foaming the foamable resin particles are filled into a molding machine, the filling property of the foamable resin particles into a narrow space becomes poor. It should be noted that the narrow space in the molding machine corresponds to a thin portion in the obtained foamed molded body. In this specification, the volume average particle size of the foamable resin particles refers to: using a particle size analyzer (such as an image processing method Millitrac JPA particle size analyzer), the particle size of the foamable resin particles is measured on a volume basis, and the result is expressed by cumulative distribution, and the particle size at which the volume accumulation becomes 50% (i.e., D50) is taken as the volume average particle size.
发泡性树脂颗粒的体积平均粒径可以通过改变(a)初期的分散剂(例如磷酸三钙、α-烯烃磺酸钠)的量、(b)聚合过程中加入的分散剂(例如磷酸三钙)的量、以及(c)聚合过程中添加分散剂的时机(例如从聚合开始至添加分散剂为止的时间)等来调节。The volume average particle size of the expandable resin particles can be adjusted by changing (a) the amount of the initial dispersant (e.g., tricalcium phosphate, sodium α-olefin sulfonate), (b) the amount of the dispersant (e.g., tricalcium phosphate) added during the polymerization, and (c) the timing of adding the dispersant during the polymerization (e.g., the time from the start of polymerization to the addition of the dispersant).
(粒度分布的峰顶粒径)(Peak particle size of particle size distribution)
本发泡性树脂颗粒的粒度分布的峰顶粒径为0.33mm～0.47mm，优选为0.35mm～0.47mm，更优选为0.40mm～0.45mm。The peak top particle diameter of the particle size distribution of the expandable resin particles is 0.33 mm to 0.47 mm, preferably 0.35 mm to 0.47 mm, and more preferably 0.40 mm to 0.45 mm.
本说明书中，发泡性树脂颗粒的粒度分布的峰顶粒径是指：使用粒度分析计(例如图像处理方式Millitrac JPA粒度分析计)，以体积基准测定发泡性树脂颗粒的粒径，以横轴为粒径(0.1mm间隔)、纵轴为体积频率的分布表示得到的结果。将得到的粒度分布中频率最多的区域(粒径)作为峰顶粒径。In this specification, the peak particle size of the particle size distribution of the foamable resin particles refers to the result obtained by measuring the particle size of the foamable resin particles on a volume basis using a particle size analyzer (e.g., an image processing method Millitrac JPA particle size analyzer), and expressing the distribution with the particle size (0.1 mm interval) on the horizontal axis and the volume frequency on the vertical axis. The region (particle size) with the highest frequency in the obtained particle size distribution is taken as the peak particle size.
(发泡性甲基丙烯酸甲酯系树脂颗粒的发泡性)(Foamability of Foamable Methyl Methacrylate Resin Particles)
对于本发泡性树脂颗粒，使该发泡性树脂颗粒在蒸气吹入压0.10MPa～0.16MPa、且发泡机内压力0.005MPa～0.030MPa的条件下进行发泡时，直至前述发泡性甲基丙烯酸甲酯系树脂颗粒成为体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒为止的时间(A)可以小于80秒。该时间(A)优选为70秒以下，更优选为50秒以下。时间(A)的下限值没有限定，但时间(A)至少超过0秒。时间(A)小于80时，可以说该发泡性树脂颗粒的发泡性优异。For the present expandable resin particles, when the expandable resin particles are expanded under the conditions of a steam blowing pressure of 0.10MPa to 0.16MPa and a pressure in a foaming machine of 0.005MPa to 0.030MPa, the time (A) until the expandable methyl methacrylate resin particles become methyl methacrylate resin foamed particles with a volume ratio of 50 times can be less than 80 seconds. The time (A) is preferably less than 70 seconds, more preferably less than 50 seconds. The lower limit of the time (A) is not limited, but the time (A) is at least more than 0 seconds. When the time (A) is less than 80, it can be said that the expandable resin particles have excellent foamability.
此处，发泡性树脂颗粒的时间(A)(发泡速度)的测定方法没有特别限定，例如可以列举依次进行以下(1)～(4)的方法：(1)将发泡性树脂颗粒投入加压式的发泡机(例如Obiraki Industry Co.,Ltd.制的BHP)；(2)接着，在蒸气吹入压0.10MPa～0.16MPa、且发泡机内压力0.005MPa～0.030MPa的条件下向发泡机内吹入蒸气(例如水蒸气)，对发泡性树脂颗粒进行加热；(3)每隔一定时间，从前述发泡机中取出前述发泡性树脂颗粒发泡而成的发泡颗粒，测量该发泡颗粒的体积倍率；(4)测量从对发泡性树脂颗粒吹入蒸气开始至得到体积倍率50倍的发泡颗粒为止的时间(A)(也可以称为加热时间(A))。Here, the method for measuring the time (A) (foaming rate) of the foamable resin particles is not particularly limited, and for example, the following methods (1) to (4) can be mentioned in sequence: (1) the foamable resin particles are placed in a pressurized foaming machine (for example, BHP manufactured by Obiraki Industry Co., Ltd.); (2) then, steam (for example, water vapor) is blown into the foaming machine under the conditions of a steam blowing pressure of 0.10 MPa to 0.16 MPa and a pressure in the foaming machine of 0.005 MPa to 0.030 MPa to heat the foamable resin particles; (3) at regular intervals, the foamable particles obtained by foaming the foamable resin particles are taken out from the foaming machine and the volume ratio of the foamable particles is measured; (4) the time (A) (also referred to as heating time (A)) from the start of blowing steam into the foamable resin particles to the obtaining of foamable particles having a volume ratio of 50 times is measured.
与以蒸气吹入压0.10MPa加热发泡性树脂颗粒的情况相比，以蒸气吹入压0.16MPa加热发泡性树脂颗粒的情况下，直至得到体积倍率50倍的发泡颗粒为止的时间变得极短，但实质上几乎没有变化。本说明书中，将在蒸气吹入压为0.10MPa～0.16MPa、且发泡机内压力为0.005MPa～0.030MPa的条件下加热发泡性树脂颗粒时直至得到体积倍率50倍的发泡颗粒为止的时间视为时间(A)。Compared with the case where the foamable resin particles are heated at a steam blowing pressure of 0.10 MPa, the time until the foamable particles having a volume ratio of 50 times are obtained when the foamable resin particles are heated at a steam blowing pressure of 0.16 MPa becomes extremely short, but there is substantially no change. In this specification, the time until the foamable particles having a volume ratio of 50 times are obtained when the foamable resin particles are heated at a steam blowing pressure of 0.10 MPa to 0.16 MPa and a pressure in the foaming machine of 0.005 MPa to 0.030 MPa is referred to as time (A).
本说明书中，发泡颗粒的体积倍率设为依次实施以下(1)～(3)而得到的值：(1)量取发泡颗粒10g，放入1000cm3的量筒中；(2)由量筒的刻度测定10g发泡颗粒的体积；(3)通过下式算出发泡颗粒的体积倍率；In this specification, the volume ratio of the foamed particles is defined as the value obtained by sequentially carrying out the following (1) to (3): (1) measuring 10 g of the foamed particles and placing them in a 1000 cm3 measuring cylinder; (2) measuring the volume of 10 g of the foamed particles from the scale of the measuring cylinder; (3) calculating the volume ratio of the foamed particles by the following formula;
体积倍率(cm3/g)＝发泡颗粒的体积(cm3)/10g。Volume ratio (cm3 /g) = volume of expanded particles (cm3 )/10 g.
本说明书中，发泡颗粒的体积倍率也称为发泡倍率。另外，体积倍率的单位实际上基于上述式为cm3/g，但本说明书中为了方便起见，将体积倍率的单位记为“倍”。In this specification, the volume ratio of expanded beads is also referred to as the expansion ratio. In addition, the unit of the volume ratio is actually cm3 /g based on the above formula, but in this specification, the unit of the volume ratio is expressed as "times" for convenience.
(重均分子量)(Weight average molecular weight)
本发泡性树脂颗粒包含的基材树脂的重均分子量可以为17.5万～28.5万。基材树脂的重均分子量为28.5万以下时，令人惊讶的是，发泡性树脂颗粒具有发泡性优异的优点。结果，发泡性树脂颗粒(发泡颗粒)具有能够提供表面美观性优异的发泡成型体的优点。基材树脂的重均分子量为17.5万以上时，具有发泡颗粒的收缩小、制成成型体时不易形成颗粒间的间隙、表面扩展率优异的优点。该重均分子量优选为20万～26万，更优选为23万～25万。The weight average molecular weight of the base resin contained in the present foamable resin particles can be 175,000 to 285,000. When the weight average molecular weight of the base resin is 285,000 or less, surprisingly, the foamable resin particles have the advantage of excellent foamability. As a result, the foamable resin particles (foamed particles) have the advantage of being able to provide a foamed molded body with excellent surface aesthetics. When the weight average molecular weight of the base resin is 175,000 or more, the foamed particles have the advantages of small shrinkage, difficulty in forming gaps between particles when made into a molded body, and excellent surface expansion rate. The weight average molecular weight is preferably 200,000 to 260,000, and more preferably 230,000 to 250,000.
本说明书中，将通过以下的方法测定而得到的重均分子量设为发泡性树脂颗粒包含的基材树脂的重均分子量：(1)使发泡性树脂颗粒0.02g溶解于四氢呋喃(以下，有时简称为“THF”)20ml中；(2)然后，过滤得到的溶解液中的凝胶成分；(3)接着，仅将可溶于THF的成分(即滤液)作为试样，使用凝胶渗透色谱(GPC)进行GPC测定；(4)由通过GPC测定而得到的GPC测定图算出重均分子量(Mw)和数均分子量(Mn)。需要说明的是，重均分子量(Mw)和数均分子量(Mn)为聚苯乙烯换算的相对值。In this specification, the weight average molecular weight obtained by the following method is set as the weight average molecular weight of the base resin contained in the foamable resin particles: (1) 0.02 g of the foamable resin particles are dissolved in 20 ml of tetrahydrofuran (hereinafter, sometimes referred to as "THF"); (2) Then, the gel component in the obtained solution is filtered; (3) Then, only the component soluble in THF (i.e., the filtrate) is used as a sample and GPC measurement is performed using gel permeation chromatography (GPC); (4) The weight average molecular weight (Mw) and the number average molecular weight (Mn) are calculated from the GPC measurement chart obtained by GPC measurement. It should be noted that the weight average molecular weight (Mw) and the number average molecular weight (Mn) are relative values converted to polystyrene.
基材树脂的重均分子量可以通过变更基材树脂的聚合(共聚)过程中使用的单体的组成(种类和量)、链转移剂的种类和量、聚合温度和时间、引发剂的种类和量、以及交联剂的种类和量等来调节。The weight average molecular weight of the base resin can be adjusted by changing the composition (type and amount) of the monomers used in the polymerization (copolymerization) process of the base resin, the type and amount of the chain transfer agent, the polymerization temperature and time, the type and amount of the initiator, and the type and amount of the crosslinking agent.
〔3.发泡性甲基丙烯酸甲酯系树脂颗粒的制造方法〕[3. Method for producing expandable methyl methacrylate resin particles]
本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒的制造方法可以包括：共聚工序，使包含甲基丙烯酸甲酯单体及丙烯酸酯单体的单体混合物共聚；以及发泡剂浸渗工序，使发泡剂浸渗在得到的共聚物中。前述共聚工序还包括：(a)引发工序，在相对于前述单体混合物100重量份为0.20重量份～1.20重量份的第一水难溶性无机盐的存在下，引发单体混合物的共聚，以及(b)添加工序，在前述引发工序后，在聚合转化率为35％～70％的时刻，在反应混合物中添加相对于前述单体混合物100重量份为0.08重量份～0.50重量份的第二水难溶性无机盐。前述共聚工序中，相对于前述甲基丙烯酸甲酯单体及前述丙烯酸酯单体的总计使用量100重量份，前述甲基丙烯酸甲酯单体的使用量优选为93.0重量份～98.0重量份，前述丙烯酸酯单体的使用量优选为2.0重量份～7.0重量份。The method for producing expandable methyl methacrylate resin particles according to one embodiment of the present invention may include: a copolymerization step of copolymerizing a monomer mixture containing methyl methacrylate monomers and acrylate monomers; and a blowing agent impregnation step of impregnating the obtained copolymer with a blowing agent. The aforementioned copolymerization step also includes: (a) an initiation step of initiating copolymerization of the monomer mixture in the presence of 0.20 to 1.20 parts by weight of a first sparingly water-soluble inorganic salt relative to 100 parts by weight of the aforementioned monomer mixture, and (b) an addition step of adding 0.08 to 0.50 parts by weight of a second sparingly water-soluble inorganic salt relative to 100 parts by weight of the aforementioned monomer mixture to the reaction mixture after the aforementioned initiation step at a time when the polymerization conversion rate is 35% to 70%. In the copolymerization step, the methyl methacrylate monomer is preferably used in an amount of 93.0 to 98.0 parts by weight, and the acrylate monomer is preferably used in an amount of 2.0 to 7.0 parts by weight, based on 100 parts by weight of the total amount of the methyl methacrylate monomer and the acrylate monomer.
本说明书中，“水难溶性无机盐”是指在25℃的水中的溶解度为0.1mg/ml以下的无机盐。In the present specification, the "poorly water-soluble inorganic salt" refers to an inorganic salt having a solubility in water at 25°C of 0.1 mg/ml or less.
以下，有时也将“本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒的制造方法”称为“本制造方法”。Hereinafter, the "method for producing expandable methyl methacrylate resin particles according to one embodiment of the present invention" may also be referred to as "the present production method".
本制造方法由于具有前述构成，因此能够提供可提供表面美观性优异的甲基丙烯酸甲酯系树脂发泡成型体的发泡性甲基丙烯酸甲酯系树脂颗粒。本制造方法由于具有前述构成，因此能够提供例如〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项中记载的本发明的一个实施方式的发泡性甲基丙烯酸甲酯系树脂颗粒。本制造方法适合用于制造〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项中记载的本发泡性树脂颗粒。需要说明的是，本制造方法中的“共聚物”相当于〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项中记载的发泡性树脂颗粒包含的“基材树脂”。Since the present production method has the aforementioned structure, it is possible to provide expandable methyl methacrylate resin particles that can provide methyl methacrylate resin foamed molded products with excellent surface aesthetics. Since the present production method has the aforementioned structure, it is possible to provide, for example, expandable methyl methacrylate resin particles of one embodiment of the present invention described in [2. Expandable methyl methacrylate resin particles]. The present production method is suitable for producing the present expandable resin particles described in [2. Expandable methyl methacrylate resin particles]. It should be noted that the "copolymer" in the present production method is equivalent to the "base resin" contained in the expandable resin particles described in [2. Expandable methyl methacrylate resin particles].
以下，对本制造方法涉及的各工序进行说明，除以下详细说明的事项以外，适当引用〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项的记载。另外，〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项中说明的本发泡性树脂颗粒优选通过本制造方法制造，但也可以通过除本制造方法以外的方法制造。即，本发泡性树脂颗粒的制造方法不限于以下说明的本制造方法的方式。Hereinafter, each step involved in the present production method will be described, and the description of the item [2. Expandable methyl methacrylate resin particles] will be appropriately cited except for the matters described in detail below. In addition, the present expandable resin particles described in the item [2. Expandable methyl methacrylate resin particles] are preferably produced by the present production method, but can also be produced by a method other than the present production method. That is, the production method of the present expandable resin particles is not limited to the method of the present production method described below.
(3-1.共聚工序)(3-1. Copolymerization step)
作为本制造方法具有的共聚工序，可以列举在水性悬浮液中进行单体混合物的聚合的悬浮聚合。以下，有时也将共聚工序中得到的共聚物(基材树脂)简称为“树脂颗粒”。The copolymerization step in the present production method may be suspension polymerization in which a monomer mixture is polymerized in an aqueous suspension. Hereinafter, the copolymer (base resin) obtained in the copolymerization step may be simply referred to as "resin particles".
本发明中的“水性悬浮液”是指使用搅拌等使单体液滴和/或树脂颗粒分散于水或水溶液中的状态的液体。水性悬浮液中，(a)可以溶解水溶性的表面活性剂和单体，另外(b)不溶于水的分散剂、聚合引发剂、链转移剂、交联剂、整泡剂、阻燃剂、溶剂、增塑剂等可以与单体一起分散。The "aqueous suspension" in the present invention refers to a liquid in which monomer droplets and/or resin particles are dispersed in water or an aqueous solution by stirring, etc. In the aqueous suspension, (a) a water-soluble surfactant and a monomer can be dissolved, and (b) a water-insoluble dispersant, a polymerization initiator, a chain transfer agent, a crosslinking agent, a foam stabilizer, a flame retardant, a solvent, a plasticizer, etc. can be dispersed together with the monomer.
水性悬浮液中的单体及聚合物(树脂)与水或水溶液的重量比以得到的甲基丙烯酸甲酯系树脂/水或水溶液之比计，优选为1.0/0.6～1.0/3.0。需要说明的是，此处提及的“水溶液”是指包含水和除甲基丙烯酸甲酯系树脂以外的成分的溶液。The weight ratio of the monomer and polymer (resin) to water or aqueous solution in the aqueous suspension is preferably 1.0/0.6 to 1.0/3.0, based on the ratio of the obtained methyl methacrylate resin to water or aqueous solution. It should be noted that the "aqueous solution" mentioned here refers to a solution containing water and components other than the methyl methacrylate resin.
共聚工序包括在相对于单体混合物100重量份为0.20重量份～1.20重量份的第一水难溶性无机盐的存在下引发单体混合物的共聚的引发工序。引发工序是例如使用包含(a)水、(b)包含甲基丙烯酸甲酯单体及丙烯酸酯单体的单体混合物、(c)相对于单体混合物100重量份为0.20重量份～1.20重量份的第一水难溶性无机盐、(d)交联剂、以及任选包含的(e)聚合引发剂、表面活性剂、除水难溶性无机盐以外的分散剂、链转移剂、整泡剂、阻燃剂、溶剂和增塑剂等的水性悬浮液，而引发单体混合物的共聚的工序。The copolymerization step includes an initiation step of initiating copolymerization of the monomer mixture in the presence of 0.20 to 1.20 parts by weight of the first sparingly water-soluble inorganic salt relative to 100 parts by weight of the monomer mixture. The initiation step is, for example, a step of initiating copolymerization of the monomer mixture using an aqueous suspension containing (a) water, (b) a monomer mixture containing methyl methacrylate monomers and acrylate monomers, (c) 0.20 to 1.20 parts by weight of the first sparingly water-soluble inorganic salt relative to 100 parts by weight of the monomer mixture, (d) a crosslinking agent, and optionally (e) a polymerization initiator, a surfactant, a dispersant other than the sparingly water-soluble inorganic salt, a chain transfer agent, a foam stabilizer, a flame retardant, a solvent, a plasticizer, and the like.
本说明书中，有时也将“聚合反应的开始前”称为“聚合初期”。引发工序中配混(添加)在水性悬浮液中的第一水难溶性无机盐和任选配混的聚合引发剂等可以说是在聚合初期使用的物质(原料)。In this specification, “before the start of the polymerization reaction” may be referred to as “initial polymerization stage.” The first poorly water-soluble inorganic salt and the optional polymerization initiator mixed (added) in the aqueous suspension in the initiation step can be said to be substances (raw materials) used in the initial polymerization stage.
引发工序中，第一水难溶性无机盐可以作为分散剂发挥作用。作为在引发工序即聚合初期使用的第一水难溶性无机盐，例如可以列举磷酸三钙、焦磷酸镁、羟基磷灰石、高岭土等。In the initiation step, the first sparingly water-soluble inorganic salt can function as a dispersant. Examples of the first sparingly water-soluble inorganic salt used in the initiation step, ie, the initial stage of polymerization, include tricalcium phosphate, magnesium pyrophosphate, hydroxyapatite, and kaolin.
另外，引发工序中，可以将(a)聚乙烯醇、甲基纤维素、聚丙烯酰胺、聚乙烯吡咯烷酮等水溶性高分子和/或(b)α-烯烃磺酸钠、十二烷基苯磺酸钠等阴离子系表面活性剂与第一水难溶性无机盐组合使用。In the initiation step, (a) a water-soluble polymer such as polyvinyl alcohol, methylcellulose, polyacrylamide, polyvinyl pyrrolidone, and/or (b) an anionic surfactant such as sodium α-olefin sulfonate, sodium dodecylbenzene sulfonate, etc. may be used in combination with the first poorly water-soluble inorganic salt.
出于对树脂颗粒和/或单体的液滴的保护能力的观点，优选磷酸三钙作为引发工序中使用的第一水难溶性无机盐。出于液滴的分散稳定性的观点，引发工序优选为在作为水难溶性无机盐的磷酸三钙和作为阴离子系表面活性剂的α-烯烃磺酸钠的存在下引发单体混合物的共聚的工序。From the viewpoint of the ability to protect the resin particles and/or the monomer droplets, tricalcium phosphate is preferably used as the first water-slightly soluble inorganic salt used in the initiation step. From the viewpoint of the dispersion stability of the droplets, the initiation step is preferably a step of initiating copolymerization of the monomer mixture in the presence of tricalcium phosphate as the water-slightly soluble inorganic salt and sodium α-olefin sulfonate as the anionic surfactant.
引发工序优选为在相对于单体混合物100重量份优选为0.20重量份～1.20重量份、更优选为0.20重量份～1.10重量份、进一步优选为0.40重量份～1.10重量份的第一水难溶性无机盐的存在下引发单体混合物的共聚的工序。在相对于单体混合物100重量份为0.20重量份以上的第一水难溶性无机盐的存在下引发单体混合物的共聚时，得到的发泡性树脂颗粒的体积平均粒径不会变得过大。在相对于单体混合物100重量份为1.10重量份以下的第一水难溶性无机盐的存在下引发单体混合物的共聚时，不会大量产生发泡性树脂颗粒的微粒。即，通过在上述范围内的量的第一水难溶性无机盐的存在下引发单体混合物的共聚，能够收率良好地得到具有期望的体积平均粒径的发泡性树脂颗粒。The initiation step is preferably a step of initiating copolymerization of the monomer mixture in the presence of a first water-sparsely soluble inorganic salt, preferably 0.20 to 1.20 parts by weight, more preferably 0.20 to 1.10 parts by weight, and further preferably 0.40 to 1.10 parts by weight, relative to 100 parts by weight of the monomer mixture. When initiating copolymerization of the monomer mixture in the presence of 0.20 parts by weight or more of the first water-sparsely soluble inorganic salt relative to 100 parts by weight of the monomer mixture, the volume average particle size of the obtained foamable resin particles will not become too large. When initiating copolymerization of the monomer mixture in the presence of 1.10 parts by weight or less of the first water-sparsely soluble inorganic salt relative to 100 parts by weight of the monomer mixture, microparticles of the foamable resin particles will not be generated in large quantities. That is, by initiating copolymerization of the monomer mixture in the presence of the first water-sparsely soluble inorganic salt in an amount within the above range, foamable resin particles having a desired volume average particle size can be obtained in good yield.
引发工序中，将水溶性高分子和/或阴离子系表面活性剂与第一水难溶性无机盐组合使用时，作为水溶性高分子和/或阴离子系表面活性剂在水性悬浮液中的浓度，以单体混合物的浓度为基准，优选为30ppm～100ppm。In the initiation step, when a water-soluble polymer and/or anionic surfactant is used in combination with the first sparingly water-soluble inorganic salt, the concentration of the water-soluble polymer and/or anionic surfactant in the aqueous suspension is preferably 30 ppm to 100 ppm based on the concentration of the monomer mixture.
共聚工序包括添加工序，所述添加工序如下：引发工序后，在聚合转化率为35％～70％的时刻，将相对于单体混合物100重量份为0.08重量份～0.50重量份的第二水难溶性无机盐添加到反应混合物中。The copolymerization step includes an adding step, wherein after the initiation step, when the polymerization conversion rate is 35% to 70%, 0.08 to 0.50 parts by weight of the second poorly water-soluble inorganic salt is added to the reaction mixture based on 100 parts by weight of the monomer mixture.
本说明书中，有时也将“聚合反应开始后”称为“聚合中途”。添加工序中，反应混合物中添加的第二水难溶性无机盐可以说是聚合过程中使用的物质(原料)。In this specification, “after the start of the polymerization reaction” may be referred to as “during the polymerization.” In the adding step, the second poorly water-soluble inorganic salt added to the reaction mixture can be regarded as a substance (raw material) used in the polymerization process.
共聚工序中的单体混合物的聚合(共聚)通过悬浮聚合进行时，添加工序中的反应混合物也可以说是水性悬浮液。When the polymerization (copolymerization) of the monomer mixture in the copolymerization step is performed by suspension polymerization, the reaction mixture in the adding step can also be said to be an aqueous suspension.
添加工序中，第二水难溶性无机盐可以作为分散剂发挥作用。作为在添加工序即聚合中途使用的第二水难溶性无机盐，可以列举作为第一水难溶性无机盐已例示的物质。作为第二水难溶性无机盐，优选为选自由磷酸三钙、羟基磷灰石和高岭土组成的组中的一种以上，更优选为磷酸三钙。根据该构成，具有如下优点：能够防止分散剂的添加(追加)以后的树脂颗粒彼此的合并，从而得到目标粒径的树脂颗粒。In the addition process, the second sparingly water-soluble inorganic salt can function as a dispersant. As the second sparingly water-soluble inorganic salt used in the addition process, i.e., in the middle of the polymerization, the substances exemplified as the first sparingly water-soluble inorganic salt can be cited. As the second sparingly water-soluble inorganic salt, it is preferably one or more selected from the group consisting of tricalcium phosphate, hydroxyapatite and kaolin, and more preferably tricalcium phosphate. According to this configuration, there is the advantage that the resin particles after the addition (addition) of the dispersant can be prevented from merging with each other, thereby obtaining resin particles of the target particle size.
添加工序优选为如下工序：在引发工序后，在聚合转化率为35％～70％的时刻，将相对于单体混合物100重量份优选为0.08重量份～0.50重量份、更优选为0.10重量份～0.50重量份、更优选为0.10重量份～0.40重量份、进一步优选为0.10重量份～0.30重量份、特别优选为0.10重量份～0.20重量份的第二水难溶性无机盐添加到反应混合物中的工序。在添加工序中，在反应混合物中添加相对于单体混合物100重量份为0.08重量份以上的第二水难溶性无机盐时，不会担心得到的发泡性树脂颗粒的体积平均粒径变得过大。添加工序中，在反应混合物中添加相对于单体混合物100重量份为0.50重量份以下的第二水难溶性无机盐时，由于水难溶性无机盐的过量使用，因此生产成本变高。即，添加工序中，通过在反应混合物中添加上述范围内的量的第二水难溶性无机盐，从而能够以较低的生产成本得到具有期望的体积平均粒径的发泡性树脂颗粒。The adding step is preferably a step of adding, after the initiation step, preferably 0.08 to 0.50 parts by weight, more preferably 0.10 to 0.50 parts by weight, more preferably 0.10 to 0.40 parts by weight, further preferably 0.10 to 0.30 parts by weight, and particularly preferably 0.10 to 0.20 parts by weight of the second sparingly water-soluble inorganic salt to the reaction mixture at a time when the polymerization conversion rate is 35% to 70%. In the adding step, when 0.08 parts by weight or more of the second sparingly water-soluble inorganic salt is added to the reaction mixture relative to 100 parts by weight of the monomer mixture, there is no concern that the volume average particle size of the obtained expandable resin particles will become too large. In the adding step, when 0.50 parts by weight or less of the second sparingly water-soluble inorganic salt is added to the reaction mixture relative to 100 parts by weight of the monomer mixture, the production cost becomes high due to excessive use of the sparingly water-soluble inorganic salt. That is, in the adding step, by adding the second poorly water-soluble inorganic salt in an amount within the above range to the reaction mixture, expandable resin particles having a desired volume average particle size can be obtained at a low production cost.
添加工序优选在聚合转化率为35％～70％的时刻、更优选在聚合转化率为40％～50％的时刻优选将第二水难溶性无机盐添加到反应混合物中。根据该构成，能够得到具有期望的体积平均粒径的发泡性树脂颗粒。关于本说明书中的聚合转化率的测定方法，在下述实施例中进行详述。The second sparingly water-soluble inorganic salt is preferably added to the reaction mixture when the polymerization conversion rate is preferably 35% to 70%, more preferably when the polymerization conversion rate is 40% to 50%. According to this configuration, expandable resin particles having a desired volume average particle size can be obtained. The method for measuring the polymerization conversion rate in this specification is described in detail in the following examples.
共聚工序优选改变聚合温度而以至少2个阶段实施。为了方便，以下将聚合温度不同的2个聚合工序称为第1聚合工序及第2聚合工序。也可以说共聚工序优选包括聚合温度不同的连续的第1聚合工序和第2聚合工序。The copolymerization step is preferably implemented in at least two stages by changing the polymerization temperature. For convenience, the following two polymerization steps with different polymerization temperatures are referred to as the first polymerization step and the second polymerization step. It can also be said that the copolymerization step preferably includes the first polymerization step and the second polymerization step with different continuous polymerization temperatures.
共聚工序例如优选包括：(a)在70℃～90℃的聚合温度下且使用低温分解型的聚合引发剂而实施的第1聚合工序，以及(b)与该第1聚合工序连续实施、在比第1聚合工序高的聚合温度(例如90℃～110℃)下且使用高温分解型的聚合引发剂而实施的第2聚合工序。共聚工序中，优选在上述第1聚合工序中进行主要的聚合反应，减少在上述第2聚合工序中残留的单体。The copolymerization step preferably includes, for example: (a) a first polymerization step carried out at a polymerization temperature of 70° C. to 90° C. and using a low-temperature decomposition type polymerization initiator, and (b) a second polymerization step carried out continuously with the first polymerization step and carried out at a polymerization temperature higher than that of the first polymerization step (e.g., 90° C. to 110° C.) and using a high-temperature decomposition type polymerization initiator. In the copolymerization step, it is preferred that the main polymerization reaction is carried out in the first polymerization step to reduce the monomers remaining in the second polymerization step.
作为聚合引发剂，可以使用通常用于制造热塑性聚合物的自由基产生型聚合引发剂。作为代表性的自由基产生型聚合引发剂，例如可以列举：(a)过氧化苯甲酰、过氧化月桂酰、过氧化苯甲酸叔丁酯、异丙基叔丁基过氧化碳酸酯、过氧化苯甲酸丁酯、过氧化-2-乙基己酸叔丁酯、过氧化新戊酸叔丁酯、过氧化异丙基碳酸叔丁酯、过氧化六氢对苯二甲酸二叔丁酯、1,1-二(叔丁基过氧化)-3,3,5-三甲基环己烷、1,1-二(叔戊基过氧化)-3,3,5-三甲基环己烷、1,1-二(叔丁基过氧化)环己烷、叔丁基过氧化-2-乙基己基单碳酸酯等有机过氧化物，以及(b)偶氮二异丁腈、偶氮二甲基戊腈等偶氮化合物。这些聚合引发剂可以单独使用1种，也可以组合使用2种以上。As the polymerization initiator, a free radical generating polymerization initiator commonly used for manufacturing thermoplastic polymers can be used. Representative free radical generating polymerization initiators include: (a) organic peroxides such as benzoyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, isopropyl tert-butyl peroxycarbonate, butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, tert-butyl peroxyisopropyl carbonate, di-tert-butyl peroxyhexahydroterephthalate, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, and tert-butylperoxy-2-ethylhexyl monocarbonate, and (b) azo compounds such as azobisisobutyronitrile and azobismethylvaleronitrile. These polymerization initiators may be used alone or in combination of two or more.
上述自由基产生型聚合引发剂中，(a)过氧化苯甲酰、过氧化月桂酰、过氧化新戊酸叔丁酯、过氧化六氢对苯二甲酸二叔丁酯、偶氮二异丁腈和偶氮二甲基戊腈为低温分解型的聚合引发剂，(b)过氧化苯甲酸叔丁酯、异丙基叔丁基过氧化碳酸酯、过氧化苯甲酸丁酯、过氧化-2-乙基己酸叔丁酯、过氧化异丙基碳酸叔丁酯、1,1-二(叔丁基过氧化)-3,3,5-三甲基环己烷、1,1-二(叔戊基过氧化)-3,3,5-三甲基环己烷、1,1-二(叔丁基过氧化)环己烷和过氧化-2-乙基己基单碳酸叔丁酯为高温分解型的聚合引发剂。Among the above-mentioned free radical generating polymerization initiators, (a) benzoyl peroxide, lauroyl peroxide, tert-butyl peroxypivalate, di-tert-butyl perhexahydroterephthalate, azobisisobutyronitrile and azobismethylvaleronitrile are low temperature decomposition type polymerization initiators, and (b) tert-butyl peroxybenzoate, isopropyl tert-butyl peroxycarbonate, butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyisopropyl carbonate, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-amylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane and tert-butyl peroxy-2-ethylhexyl monocarbonate are high temperature decomposition type polymerization initiators.
关于聚合引发剂的使用量，将第1聚合工序中的使用量和第2聚合工序中的使用量合计，例如相对于单体混合物100重量份，优选为0.05重量份～0.5重量份以下。根据该构成，可得到发泡性优异的发泡性树脂颗粒。The amount of the polymerization initiator used is preferably 0.05 to 0.5 parts by weight based on 100 parts by weight of the monomer mixture, the total amount used in the first polymerization step and the amount used in the second polymerization step. With this configuration, expandable resin particles having excellent expandability can be obtained.
引发工序可以是(a)在第一水难溶性无机盐、低温分解型聚合引发剂和高温分解型聚合引发剂的存在下引发单体混合物的共聚的工序，也可以是(b)在第一水难溶性无机盐和低温分解型聚合引发剂的存在下引发单体混合物的共聚的工序。当引发工序是在第一水难溶性无机盐和低温分解型聚合引发剂的存在下引发单体混合物的共聚的工序时，高温分解型聚合引发剂可以在引发工序后即聚合中途，添加到反应混合物(水性悬浮液)中。The initiation step may be (a) a step of initiating copolymerization of the monomer mixture in the presence of the first poorly water-soluble inorganic salt, the low-temperature decomposition type polymerization initiator, and the high-temperature decomposition type polymerization initiator, or (b) a step of initiating copolymerization of the monomer mixture in the presence of the first poorly water-soluble inorganic salt and the low-temperature decomposition type polymerization initiator. When the initiation step is a step of initiating copolymerization of the monomer mixture in the presence of the first poorly water-soluble inorganic salt and the low-temperature decomposition type polymerization initiator, the high-temperature decomposition type polymerization initiator may be added to the reaction mixture (aqueous suspension) after the initiation step, i.e., during the polymerization.
共聚工序中，优选使用链转移剂。作为链转移剂，没有特别限定，可以使用甲基丙烯酸甲酯系树脂的聚合中使用的公知的物质。作为链转移剂，例如可以列举：(a)烷基硫醇类、巯基乙酸酯类等单官能链转移剂，以及(b)将乙二醇、新戊二醇、三羟甲基丙烷、山梨醇等多元醇羟基用巯基乙酸或3-巯基丙酸进行酯化而成的多官能性链转移剂。作为烷基硫醇类，可以列举正辛基硫醇、正十二烷基硫醇及叔十二烷基硫醇等。链转移剂的使用量例如相对于基材树脂100重量份优选为0.100重量份以上且小于0.500重量份，更优选为0.270重量份以上且小于0.340重量份。In the copolymerization process, a chain transfer agent is preferably used. As a chain transfer agent, there is no particular limitation, and known substances used in the polymerization of methyl methacrylate resins can be used. As a chain transfer agent, for example, monofunctional chain transfer agents such as (a) alkyl mercaptans and thioglycolic acid esters, and (b) polyfunctional chain transfer agents formed by esterifying polyol hydroxyl groups such as ethylene glycol, neopentyl glycol, trimethylolpropane, and sorbitol with thioglycolic acid or 3-mercaptopropionic acid. As alkyl mercaptans, n-octyl mercaptan, n-dodecyl mercaptan, and tert-dodecyl mercaptan can be listed. The amount of the chain transfer agent used is preferably 0.100 parts by weight or more and less than 0.500 parts by weight, and more preferably 0.270 parts by weight or more and less than 0.340 parts by weight relative to 100 parts by weight of the substrate resin.
(3-2.发泡剂浸渗工序)(3-2. Foaming agent impregnation step)
发泡剂浸渗工序中，通过使发泡剂浸渗于共聚工序中得到的作为共聚物的甲基丙烯酸甲酯系树脂颗粒，从而能够得到发泡性甲基丙烯酸甲酯系树脂颗粒。In the blowing agent impregnation step, the methyl methacrylate resin particles as the copolymer obtained in the copolymerization step are impregnated with the blowing agent, thereby obtaining expandable methyl methacrylate resin particles.
发泡剂浸渗工序可以在任意的时刻进行，例如可以与第2聚合工序一起进行，或者可以在第2聚合工序之后进行。The blowing agent impregnation step may be performed at any time, and may be performed together with the second polymerization step, or may be performed after the second polymerization step.
发泡剂浸渗工序优选在从单体到共聚物的聚合转化率为80％～95％的时刻，使发泡剂浸渗于得到的共聚物中。在聚合转化率为80％以上的时刻使发泡剂浸渗于共聚物时，发泡剂被适度地浸渗于共聚物的内部，因此不会因共聚物的软化而产生共聚物彼此的凝聚，制造收率变得良好。在聚合转化率为95％以下的时刻使发泡剂浸渗于共聚物时，发泡剂充分浸渗至共聚物的内部，因此使得到的发泡性树脂颗粒进行发泡而成的发泡颗粒中不会形成双重的气泡结构(硬芯)。结果，通过对该发泡颗粒进行模内成型，从而能够得到表面美观性优异的发泡成型体。The foaming agent impregnation step is preferably performed by impregnating the obtained copolymer with the foaming agent at a time when the polymerization conversion rate from the monomer to the copolymer is 80% to 95%. When the foaming agent is impregnated into the copolymer at a time when the polymerization conversion rate is 80% or more, the foaming agent is moderately impregnated into the interior of the copolymer, so that the copolymers will not coagulate with each other due to the softening of the copolymer, and the manufacturing yield becomes good. When the foaming agent is impregnated into the copolymer at a time when the polymerization conversion rate is 95% or less, the foaming agent is fully impregnated into the interior of the copolymer, so that the foamed particles obtained by foaming the foamable resin particles will not form a double bubble structure (hard core). As a result, by in-mold molding of the foamed particles, a foamed molded body with excellent surface aesthetics can be obtained.
发泡剂浸渗工序中，对于浸渗于作为共聚物的甲基丙烯酸甲酯系树脂颗粒的发泡剂的量，包括优选的方式在内，与〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕的(发泡剂)一项中记载的发泡性树脂颗粒中的发泡剂的含量相同。根据该构成，能够得到具有充分的发泡性的发泡性树脂颗粒，并且发泡剂浸渗工序中不会引起共聚物的凝聚，能够安全地制造发泡性树脂颗粒。In the step of impregnating the methyl methacrylate resin particles as the copolymer, the amount of the foaming agent impregnated therein is the same as the content of the foaming agent in the foamable resin particles described in the section (foaming agent) of [2. Foamable methyl methacrylate resin particles], including a preferred embodiment. According to this configuration, foamable resin particles having sufficient foamability can be obtained, and the copolymer does not aggregate in the step of impregnating the foaming agent, so that the foamable resin particles can be safely produced.
发泡剂浸渗工序中，使发泡剂浸渗于共聚物中时的处理温度(也称为浸渗温度)及处理时间(也称为浸渗时间)没有特别限定。In the blowing agent impregnation step, the treatment temperature (also referred to as impregnation temperature) and the treatment time (also referred to as impregnation time) when impregnating the copolymer with the blowing agent are not particularly limited.
发泡剂浸渗工序中，使发泡剂浸渗于共聚物中时的浸渗温度优选为95℃～120℃以下，更优选为100℃～117℃以下。浸渗温度为95℃以上时，发泡剂充分地浸渗至共聚物的内部，因此不会担心使得到的发泡性树脂颗粒发泡而成的发泡颗粒中形成双重的气泡结构(硬芯)。结果，通过对该发泡颗粒进行模内成型，从而能够得到表面美观性优异的发泡成型体。浸渗温度为120℃以下时，聚合机内的压力不会变得过高，因此在不需要能够耐受较大压力的重装浸渗设备的情况下，能够得到可提供具有均匀的气泡结构的发泡颗粒的发泡性树脂颗粒。In the foaming agent impregnation process, the impregnation temperature when the foaming agent is impregnated into the copolymer is preferably below 95°C to 120°C, and more preferably below 100°C to 117°C. When the impregnation temperature is above 95°C, the foaming agent is fully impregnated into the interior of the copolymer, so there is no concern about the formation of a double bubble structure (hard core) in the foamed particles obtained by foaming the foamable resin particles. As a result, by in-mold molding the foamed particles, a foamed molded body with excellent surface aesthetics can be obtained. When the impregnation temperature is below 120°C, the pressure in the polymerization machine will not become too high, so foamable resin particles that can provide foamed particles with a uniform bubble structure can be obtained without the need for heavy-duty impregnation equipment that can withstand high pressures.
本制造方法中，使用溶剂(例如沸点50℃以上的溶剂)时，优选在即将进行发泡剂浸渗工序之前或与发泡剂浸渗工序同时，将溶剂添加到反应混合物(水性悬浮液)中。In the present production method, when a solvent (for example, a solvent having a boiling point of 50° C. or higher) is used, the solvent is preferably added to the reaction mixture (aqueous suspension) immediately before or simultaneously with the blowing agent impregnation step.
〔4.甲基丙烯酸甲酯系树脂发泡颗粒〕[4. Methyl methacrylate resin foam particles]
本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡颗粒是将〔2.发泡性甲基丙烯酸甲酯系树脂颗粒〕一项中记载的发泡性甲基丙烯酸甲酯系树脂颗粒、或通过〔3.发泡性甲基丙烯酸甲酯系树脂颗粒的制造方法〕一项中记载的制造方法而制造的对发泡性甲基丙烯酸甲酯系树脂颗粒进行发泡而成的发泡颗粒。The methyl methacrylate resin foamed particles according to one embodiment of the present invention are foamed particles obtained by foaming the foamable methyl methacrylate resin particles described in [2. Foamable methyl methacrylate resin particles] or the foamable methyl methacrylate resin particles produced by the production method described in [3. Production method of foamable methyl methacrylate resin particles].
以下，有时也将“本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡颗粒”称为“本发泡颗粒”。Hereinafter, “the methyl methacrylate resin foamed particles according to one embodiment of the present invention” may also be referred to as “the present foamed particles”.
本发泡性树脂颗粒可以通过一般的发泡方法制成发泡颗粒。具体而言，例如通过依次进行以下的(1)～(3)的操作，从而能够得到甲基丙烯酸甲酯系树脂发泡颗粒：(1)在具备搅拌机的容器内投入发泡性甲基丙烯酸甲酯系树脂颗粒；(2)利用水蒸气等热源加热该发泡性甲基丙烯酸甲酯系树脂颗粒；(3)通过前述(2)，进行发泡直至期望的发泡倍率为止，从而得到甲基丙烯酸甲酯系树脂发泡颗粒。The present expandable resin particles can be made into expandable particles by a general expansion method. Specifically, for example, the following operations (1) to (3) can be performed in sequence to obtain expandable methyl methacrylate resin particles: (1) adding expandable methyl methacrylate resin particles into a container equipped with a stirrer; (2) heating the expandable methyl methacrylate resin particles using a heat source such as steam; (3) foaming the expandable methyl methacrylate resin particles according to the above (2) until the desired expansion ratio is reached, thereby obtaining expandable methyl methacrylate resin particles.
发泡性甲基丙烯酸甲酯系树脂颗粒的发泡也可以说是为了由该发泡性甲基丙烯酸甲酯系树脂颗粒得到后述的甲基丙烯酸甲酯系树脂发泡成型体而预先进行的发泡。因此，发泡性甲基丙烯酸甲酯系树脂颗粒的发泡有时也称为“预发泡”，有时也将甲基丙烯酸甲酯系树脂发泡颗粒称为“甲基丙烯酸甲酯系树脂预发泡颗粒”。The foaming of the expandable methyl methacrylate resin particles can also be said to be foaming performed in advance in order to obtain the methyl methacrylate resin foamed molded product described later from the expandable methyl methacrylate resin particles. Therefore, the foaming of the expandable methyl methacrylate resin particles is sometimes also referred to as "pre-foaming", and the methyl methacrylate resin foamed particles are sometimes referred to as "methyl methacrylate resin pre-foamed particles".
本发泡颗粒的填充性优异。发泡颗粒的填充性可以依次实施以下的(1)～(5)来进行评价。(1)将本发泡颗粒(例如体积倍率50倍的本发泡颗粒)在常温(例如25℃)下放置(例如放置3天)；(2)向具有纵450mm、横300mm及厚度30mm的模具的成型机中填充本发泡颗粒；(3)以蒸气吹入压0.10MPa～0.50MPa向模具内吹入水蒸气，在模具内的压力为0.030MPa～0.100MPa的条件下，进行利用真空抽吸加热的模内成型，直至发泡压力成为0.100MPa～0.180MPa为止，使本发泡颗粒彼此熔接；(4)发泡压力达到0.100MPa～0.180MPa后，将模具放置200秒，然后，取出发泡成型体；(5)通过目视确认得到的发泡成型体的填充不良部位。The present expanded beads are excellent in filling properties. The filling properties of the expanded beads can be evaluated by sequentially carrying out the following (1) to (5). (1) The foamed particles (e.g., the foamed particles with a volume ratio of 50 times) are placed at room temperature (e.g., 25°C) (e.g., for 3 days); (2) The foamed particles are filled into a molding machine having a mold with a length of 450 mm, a width of 300 mm, and a thickness of 30 mm; (3) Water vapor is blown into the mold at a steam blowing pressure of 0.10 MPa to 0.50 MPa, and under the condition that the pressure in the mold is 0.030 MPa to 0.100 MPa, in-mold molding using vacuum suction heating is performed until the foaming pressure becomes 0.100 MPa to 0.180 MPa, so that the foamed particles are fused to each other; (4) After the foaming pressure reaches 0.100 MPa to 0.180 MPa, the mold is placed for 200 seconds, and then the foamed molded body is taken out; (5) The poorly filled parts of the obtained foamed molded body are visually confirmed.
〔5.甲基丙烯酸甲酯系树脂发泡成型体〕[5. Methyl methacrylate resin foamed product]
本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡成型体是对〔4.甲基丙烯酸甲酯系树脂发泡颗粒〕一项中记载的甲基丙烯酸甲酯系树脂发泡颗粒进行模内成型而成的发泡成型体。The methyl methacrylate resin foam molded article according to one embodiment of the present invention is a foam molded article obtained by in-mold molding the methyl methacrylate resin foamed particles described in the section [4. Methyl methacrylate resin foamed particles].
以下有时也将“本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡成型体”称为“本发泡成型体”。Hereinafter, the "methyl methacrylate-based resin foamed molded product according to one embodiment of the present invention" may also be referred to as the "present foamed molded product".
本发泡颗粒可以通过利用一般的模内成型方法进行成型而制成发泡成型体。具体而言，例如通过依次进行以下的(1)～(3)的操作，从而能够得到甲基丙烯酸甲酯系树脂发泡成型体：(1)在能够封闭但不能密闭的模具内填充甲基丙烯酸甲酯系树脂发泡颗粒；(2)通过水蒸气加热该甲基丙烯酸甲酯系树脂发泡颗粒；(3)通过上述(2)使该甲基丙烯酸甲酯系树脂发泡颗粒彼此熔接，由此得到甲基丙烯酸甲酯系树脂发泡成型体。The foamed particles can be molded into a foamed molded article by a general in-mold molding method. Specifically, for example, the methyl methacrylate resin foamed molded article can be obtained by sequentially performing the following operations (1) to (3): (1) filling a mold that can be closed but not airtight with methyl methacrylate resin foamed particles; (2) heating the methyl methacrylate resin foamed particles with water vapor; (3) fusing the methyl methacrylate resin foamed particles to each other by the above (2), thereby obtaining a methyl methacrylate resin foamed molded article.
本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡成型体具有表面美观性优异以及燃烧时的残渣少的优点。基于这些理由，本发明的一个实施方式的甲基丙烯酸甲酯系树脂发泡成型体可以适合用作消失模。The methyl methacrylate resin foam molded product according to one embodiment of the present invention has the advantages of excellent surface appearance and less residue during combustion. For these reasons, the methyl methacrylate resin foam molded product according to one embodiment of the present invention can be suitably used as a lost foam.
〔6.消失模〕〔6. Lost foam〕
本发明的一个实施方式的消失模包含〔5.甲基丙烯酸甲酯系树脂发泡成型体〕一项中记载的甲基丙烯酸甲酯系树脂发泡成型体。The lost foam according to one embodiment of the present invention includes the methyl methacrylate resin foam molded article described in the section [5. Methyl methacrylate resin foam molded article].
本发明的一个实施方式的消失模的表面美观性优异，因此能够适用于各种金属铸造。The lost foam pattern according to one embodiment of the present invention is excellent in surface appearance and can therefore be applied to various metal castings.
〔7.其他〕〔7. Other〕
本发明可以如同以下的构成。The present invention can be constructed as follows.
〔1〕一种发泡性甲基丙烯酸甲酯系树脂颗粒，其包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，使前述发泡性甲基丙烯酸甲酯系树脂颗粒在蒸气吹入压为0.10MPa～0.16MPa、且发泡机内压为0.005MPa～0.030MPa的条件下发泡时，直至前述发泡性甲基丙烯酸甲酯系树脂颗粒成为体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒为止的时间(A)小于80秒。[1] A foamable methyl methacrylate resin particle comprising a base resin and a foaming agent, wherein the base resin comprises a methyl methacrylate unit and an acrylate unit as structural units, the volume average particle size of the foamable methyl methacrylate resin particle is 0.30 mm to 0.50 mm, and the peak particle size of the particle size distribution is 0.33 mm to 0.47 mm, and when the foamable methyl methacrylate resin particle is foamed under the conditions of a steam blowing pressure of 0.10 MPa to 0.16 MPa and an internal pressure of a foaming machine of 0.005 MPa to 0.030 MPa, the time (A) until the foamable methyl methacrylate resin particle becomes a foamed methyl methacrylate resin particle having a volume ratio of 50 times is less than 80 seconds.
〔2〕如〔1〕所述的的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述丙烯酸酯单元为丙烯酸丁酯单元。[2] The expandable methyl methacrylate resin particles according to [1], wherein the acrylic acid ester unit is a butyl acrylate unit.
〔3〕如〔1〕或〔2〕所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述基材树脂的重均分子量为17.5万～28.5万。[3] The expandable methyl methacrylate resin particles according to [1] or [2], wherein the weight average molecular weight of the base resin is 175,000 to 285,000.
〔4〕一种发泡性甲基丙烯酸甲酯系树脂颗粒，其包含基材树脂与发泡剂，前述基材树脂包含甲基丙烯酸甲酯单元及丙烯酸酯单元作为结构单元，前述丙烯酸酯单元为丙烯酸丁酯单元，在将前述基材树脂中的前述甲基丙烯酸甲酯单元及前述丙烯酸丁酯单元的总计含量设为100重量份的情况下，前述甲基丙烯酸甲酯单元的含量为93.0重量份～98.0重量份，前述丙烯酸丁酯单元的含量为2.0重量份～7.0重量份，前述发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径为0.30mm～0.50mm，且粒度分布的峰顶粒径为0.33mm～0.47mm，前述基材树脂的重均分子量为17.5万～28.5万。[4] A foamable methyl methacrylate resin particle comprising a base resin and a foaming agent, wherein the base resin comprises a methyl methacrylate unit and an acrylate unit as structural units, the acrylate unit being a butyl acrylate unit, and when the total content of the methyl methacrylate unit and the butyl acrylate unit in the base resin is 100 parts by weight, the content of the methyl methacrylate unit is 93.0 parts by weight to 98.0 parts by weight, and the content of the butyl acrylate unit is 2.0 parts by weight to 7.0 parts by weight, the volume average particle size of the foamable methyl methacrylate resin particle is 0.30 mm to 0.50 mm, and the peak particle size of the particle size distribution is 0.33 mm to 0.47 mm, and the weight average molecular weight of the base resin is 175,000 to 285,000.
〔5〕如〔1〕～〔4〕中任一项所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述发泡剂包含：(a)为碳原子数3以上且5以下的烃的脂肪族烃类和/或(b)挥发性发泡剂。[5] The expandable methyl methacrylate resin particles according to any one of [1] to [4], wherein the blowing agent comprises: (a) an aliphatic hydrocarbon having 3 to 5 carbon atoms and/or (b) a volatile blowing agent.
〔6〕如〔1〕～〔5〕中任一项所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，相对于前述基材树脂100重量份，前述发泡剂的含量为5重量份～12重量份。[6] The expandable methyl methacrylate resin particles according to any one of [1] to [5], wherein the content of the foaming agent is 5 to 12 parts by weight based on 100 parts by weight of the base resin.
〔7〕如〔1〕～〔6〕中任一项所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述基材树脂包含源自交联剂的结构单元。[7] The expandable methyl methacrylate resin particles according to any one of [1] to [6], wherein the base resin contains a structural unit derived from a crosslinking agent.
〔8〕如〔7〕所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述基材树脂包含源自二官能性单体的结构单元即二官能性单体单元作为前述源自交联剂的结构单元。[8] The expandable methyl methacrylate resin particles according to [7], wherein the base resin contains a structural unit derived from a bifunctional monomer, that is, a bifunctional monomer unit as the structural unit derived from the crosslinking agent.
〔9〕如〔7〕或〔8〕所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，前述基材树脂中，相对于前述甲基丙烯酸甲酯单元及前述丙烯酸酯单元的总量100重量份，前述源自交联剂的结构单元的含量为0重量份以上且小于0.20重量份。[9] The expandable methyl methacrylate resin particles according to [7] or [8], wherein the content of the structural unit derived from the crosslinking agent in the base resin is 0 parts by weight or more and less than 0.20 parts by weight relative to 100 parts by weight of the total amount of the methyl methacrylate units and the acrylate units.
〔10〕如〔1〕～〔9〕中任一项所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其还包含增塑剂。[10] The expandable methyl methacrylate resin particles according to any one of [1] to [9], further comprising a plasticizer.
〔11〕如〔10〕所述的发泡性甲基丙烯酸甲酯系树脂颗粒，其中，相对于前述基材树脂100重量份，前述增塑剂的含量为0.40重量份～4.00重量份。[11] The expandable methyl methacrylate resin particles according to [10], wherein the content of the plasticizer is 0.40 to 4.00 parts by weight based on 100 parts by weight of the base resin.
〔12〕一种甲基丙烯酸甲酯系树脂发泡颗粒，其为对〔1〕～〔11〕中任一项所述的发泡性甲基丙烯酸甲酯系树脂颗粒进行发泡而成的。[12] Methyl methacrylate resin foamed particles obtained by foaming the foamable methyl methacrylate resin particles according to any one of [1] to [11].
〔13〕一种甲基丙烯酸甲酯系树脂发泡成型体，其为对〔12〕所述的甲基丙烯酸甲酯系树脂发泡颗粒进行模内成型而成的。[13] A methyl methacrylate resin foamed molded product obtained by in-mold molding the methyl methacrylate resin foamed particles described in [12].
〔14〕一种消失模，其包含〔13〕所述的甲基丙烯酸甲酯系树脂发泡成型体。[14] A lost foam mold comprising the methyl methacrylate resin foam molded product described in [13].
实施例Example
以下列举实施例及比较例来更详细地说明本发明的一个实施方式，但本发明不受它们的限定。An embodiment of the present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
(发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径、峰顶粒径及均匀性)(Volume Average Particle Diameter, Peak Top Particle Diameter and Uniformity of Expandable Methyl Methacrylate Resin Particles)
使用图像处理方式Millitrac JPA粒度分析计，以体积基准用切割宽度0.005mm间隔测定发泡性甲基丙烯酸甲酯系树脂颗粒的粒径。将得到的结果用累积分布表示，将体积累积成为50％的粒径作为体积平均粒径。另外，将得到的粒度分布中频率最多的区域作为峰顶粒径。The particle size of the foamable methyl methacrylate resin particles was measured by using a Millitrac JPA particle size analyzer with an image processing method, with a cutting width of 0.005 mm intervals on a volume basis. The obtained results were expressed as a cumulative distribution, and the particle size at which the volume accumulation reached 50% was taken as the volume average particle size. In addition, the region with the highest frequency in the obtained particle size distribution was taken as the peak particle size.
基于下述指标，评价发泡性甲基丙烯酸甲酯系树脂颗粒的均匀性：The uniformity of the expandable methyl methacrylate resin particles was evaluated based on the following indicators:
A(非常良好)：峰顶粒径为0.33mm～0.47mmA (very good): Peak particle size is 0.33 mm to 0.47 mm
B(不良)：峰顶粒径小于0.33mm或超过0.47mm。B (bad): The peak particle size is less than 0.33 mm or exceeds 0.47 mm.
(基材树脂的重均分子量)(Weight average molecular weight of base resin)
将通过以下的方法测定而得到的重均分子量作为发泡性树脂颗粒包含的基材树脂的重均分子量：(1)使发泡性树脂颗粒0.02g溶解于THF20ml中；(2)然后，将得到的溶解液中的凝胶成分过滤；(3)接着，仅将可溶于THF的成分(即滤液)作为试样，使用凝胶渗透色谱(GPC)，在以下的条件下进行GPC测定；(4)由通过GPC测定得到的GPC测定图，算出重均分子量(Mw)及数均分子量(Mn)。需要说明的是，重均分子量(Mw)及数均分子量(Mn)为聚苯乙烯换算的相对值。The weight average molecular weight obtained by the following method is used as the weight average molecular weight of the base resin contained in the foamable resin particles: (1) 0.02 g of the foamable resin particles are dissolved in 20 ml of THF; (2) Then, the gel component in the obtained solution is filtered; (3) Then, only the component soluble in THF (i.e., the filtrate) is used as a sample, and a GPC measurement is performed using gel permeation chromatography (GPC) under the following conditions; (4) The weight average molecular weight (Mw) and the number average molecular weight (Mn) are calculated from the GPC measurement chart obtained by the GPC measurement. It should be noted that the weight average molecular weight (Mw) and the number average molecular weight (Mn) are relative values converted to polystyrene.
<GPC测定的条件><GPC Measurement Conditions>
测定装置：东曹株式会社制、高速GPC装置HLC-8220Measuring device: Tosoh Corporation, high-speed GPC device HLC-8220
使用柱：东曹株式会社制、SuperHZM-H×2根、SuperH-RC×2根柱温：40℃，流动相：THF(四氢呋喃)Column used: Tosoh Corporation, SuperHZM-H × 2, SuperH-RC × 2 Column temperature: 40°C, mobile phase: THF (tetrahydrofuran)
流量：0.35ml/分钟，注入量：10μlFlow rate: 0.35ml/min, injection volume: 10μl
检测器：RI。Detector: RI.
(甲基丙烯酸甲酯系树脂发泡颗粒的发泡性)(Foamability of Methyl Methacrylate Resin Foamed Particles)
使用发泡性甲基丙烯酸甲酯系树脂颗粒，依次进行以下(1)～(3)，得到体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒：(1)将发泡性甲基丙烯酸甲酯系树脂颗粒投入作为加压式的发泡机的Obiraki Industry Co.,Ltd.制的BHP 110中；(2)在蒸气吹入压0.10MPa～0.16MPa、且发泡机内压力0.005MPa～0.030MPa的条件下向发泡机内吹入水蒸气，对发泡性甲基丙烯酸甲酯系树脂颗粒进行加热；(3)通过上述(2)，进行发泡性甲基丙烯酸甲酯系树脂颗粒的发泡，直至体积倍率成为50倍为止，得到体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒。另外，测定发泡性甲基丙烯酸甲酯系树脂颗粒到达体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒为止的加热时间。Using expandable methyl methacrylate resin particles, the following (1) to (3) are sequentially performed to obtain expandable methyl methacrylate resin particles having a volume ratio of 50 times: (1) the expandable methyl methacrylate resin particles are placed in a pressure-type foaming machine, BHP 110 manufactured by Obiraki Industry Co., Ltd.; (2) steam is blown into the foaming machine under the conditions of a steam blowing pressure of 0.10 MPa to 0.16 MPa and a pressure in the foaming machine of 0.005 MPa to 0.030 MPa to heat the expandable methyl methacrylate resin particles; (3) the expandable methyl methacrylate resin particles are expanded by the above (2) until the volume ratio reaches 50 times, thereby obtaining expandable methyl methacrylate resin particles having a volume ratio of 50 times. In addition, the heating time until the expandable methyl methacrylate resin particles reach the volume ratio of 50 times is measured.
基于下述指标，评价甲基丙烯酸甲酯系树脂发泡颗粒的发泡性：The foamability of methyl methacrylate resin foam particles was evaluated based on the following indicators:
A(非常良好)：加热时间70秒以下A (very good): heating time is less than 70 seconds
B(良好)：加热时间80秒以下B (good): heating time is less than 80 seconds
C(不良)：加热时间超过80秒。C (bad): The heating time exceeds 80 seconds.
(甲基丙烯酸甲酯系树脂发泡颗粒的填充性)(Filling properties of methyl methacrylate resin foamed particles)
使用甲基丙烯酸甲酯系树脂发泡颗粒，依次实施以下的(1)～(4)，得到甲基丙烯酸甲酯系树脂发泡成型体：(1)将体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒在常温(25℃)下放置3天；(2)在具有纵450mm、横300mm及厚度10mm的模具的成型机(DAISEN制KR-57)中填充体积倍率50倍的甲基丙烯酸甲酯系树脂发泡颗粒；(3)以蒸气吹入压0.10MPa～0.50MPa向模具内吹入水蒸气，在模具内的压力为0.030MPa～0.100MPa的条件下，进行利用真空抽吸加热的模内成型直至发泡压力成为0.100MPa～0.180MPa为止，使甲基丙烯酸甲酯系树脂发泡颗粒彼此熔接；(4)发泡压力达到0.100MPa～0.180MPa后，将模具放置200秒，其后，取出发泡成型体。Using methyl methacrylate resin foam particles, the following (1) to (4) are sequentially performed to obtain a methyl methacrylate resin foam molded article: (1) 50-fold volume ratio methyl methacrylate resin foam particles are allowed to stand at room temperature (25° C.) for 3 days; (2) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine (KR-57 manufactured by DAISEN) having a mold having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (3) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a mold having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (4) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (5) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (6) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (7) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (8) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (9) 50-fold volume ratio methyl methacrylate resin foam particles are filled in a molding machine having a length of 450 mm, a width of 300 mm, and a thickness of 10 mm; (1 Water vapor is blown into the mold at a blowing pressure of 0.10MPa to 0.50MPa, and under the condition that the pressure in the mold is 0.030MPa to 0.100MPa, in-mold molding using vacuum suction heating is performed until the foaming pressure reaches 0.100MPa to 0.180MPa, so that the methyl methacrylate resin foam particles are welded to each other; (4) after the foaming pressure reaches 0.100MPa to 0.180MPa, the mold is left for 200 seconds, and then the foamed molded body is taken out.
通过目视确认得到的甲基丙烯酸甲酯系树脂发泡成型体的填充不良部位，基于下述指标，评价甲基丙烯酸甲酯系树脂发泡颗粒的填充性：The filling properties of the methyl methacrylate resin foamed particles were evaluated based on the following indices by visually confirming the poorly filled portions of the obtained methyl methacrylate resin foamed molded product:
A(良好)：没有填充不良部位A (good): No filling defects
B(不良)：存在填充不良部位。B (bad): There is a poorly filled area.
(甲基丙烯酸甲酯系树脂发泡成型体的表面美观性)(Surface aesthetics of methyl methacrylate resin foamed molded article)
通过目视观察甲基丙烯酸甲酯系树脂发泡成型体的表面，基于下述指标，评价甲基丙烯酸甲酯系树脂发泡成型体的表面美观性。需要说明的是，对于构成甲基丙烯酸甲酯系树脂发泡成型体的甲基丙烯酸甲酯系树脂发泡颗粒之间的间隙的程度，在0(颗粒间的间隙完全未填满)～5分(颗粒间的间隙完全填满)之间，以0.25分间隔的分数进行评价：The surface aesthetics of the methyl methacrylate resin foamed molded product was evaluated by visually observing the surface of the methyl methacrylate resin foamed molded product based on the following indexes. It should be noted that the degree of gaps between the methyl methacrylate resin foamed particles constituting the methyl methacrylate resin foamed molded product was evaluated with scores at intervals of 0.25 points between 0 (the gaps between the particles were not completely filled) and 5 points (the gaps between the particles were completely filled):
A(非常良好)：发泡颗粒间的间隙为4.50分以上，且填充性及峰顶粒径非常良好A (very good): The gap between foamed particles is 4.50 points or more, and the filling property and peak particle size are very good.
B(良好)：发泡颗粒间的间隙为4.25分以上且小于4.50，且填充性及峰顶粒径非常良好B (good): The gap between foamed particles is 4.25 or more and less than 4.50, and the filling property and peak particle size are very good.
C(不良)：发泡颗粒间的间隙小于4.25分，峰顶粒径不良，或填充性不良。C (poor): The gap between the foamed particles is less than 4.25 minutes, the peak particle size is poor, or the filling property is poor.
(发泡性甲基丙烯酸甲酯系树脂颗粒的聚合转化率)(Polymerization conversion rate of foamable methyl methacrylate resin particles)
在聚合中进行水性悬浮液的取样，过滤该水性悬浮液。称量残留在滤纸上的树脂成分的重量，将得到的重量作为加热前重量。接着，在该树脂成分中加入阻聚剂后，在150℃下将树脂成分加热30分钟，由此除去挥发成分。然后，计量得到的树脂成分的重量，将得到的重量作为加热后重量。使用下述式算出聚合转化率。During the polymerization, the aqueous suspension was sampled and filtered. The weight of the resin component remaining on the filter paper was weighed, and the obtained weight was taken as the weight before heating. Next, after adding a polymerization inhibitor to the resin component, the resin component was heated at 150°C for 30 minutes to remove the volatile components. Then, the weight of the obtained resin component was measured, and the obtained weight was taken as the weight after heating. The polymerization conversion rate was calculated using the following formula.
聚合转化率(％)＝加热后重量/加热前重量×100。Polymerization conversion rate (%) = weight after heating/weight before heating×100.
(实施例1)(Example 1)
在带搅拌机的6L高压釜中加入水150重量份、作为第一水难溶性无机盐的磷酸三钙0.53重量份、α-烯烃磺酸钠0.0075重量份、过氧化月桂酰0.08重量份、1,1-二(叔丁基过氧化)环己烷0.1重量份、作为交联剂的1,6-己二醇二丙烯酸酯0.1重量份、正十二烷基硫醇0.300重量份和Sumi soap 0.03重量份，制备包含第一水难溶性无机盐的混合液。然后，在该混合液中投入作为单体混合物的甲基丙烯酸甲酯95.0重量份及丙烯酸丁酯5.0重量份、甲苯1.0重量份，制备水性悬浮液。接着，将水性悬浮液的温度升温至80℃，引发聚合，即实施引发工序。从聚合开始经过1小时45分钟后(引发工序后)，测定聚合转化率，结果为40％～50％。从聚合开始经过1小时45分钟后(引发工序后)，将作为第二水难溶性无机盐的磷酸三钙0.12重量份添加到反应混合物(水性悬浮液)中，实施添加工序。In a 6L autoclave equipped with a stirrer, 150 parts by weight of water, 0.53 parts by weight of tricalcium phosphate as the first water-insoluble inorganic salt, 0.0075 parts by weight of sodium α-olefin sulfonate, 0.08 parts by weight of lauroyl peroxide, 0.1 parts by weight of 1,1-di(tert-butylperoxy)cyclohexane, 0.1 parts by weight of 1,6-hexanediol diacrylate as a crosslinking agent, 0.300 parts by weight of n-dodecyl mercaptan, and 0.03 parts by weight of Sumi soap were added to prepare a mixed solution containing the first water-insoluble inorganic salt. Then, 95.0 parts by weight of methyl methacrylate and 5.0 parts by weight of butyl acrylate and 1.0 parts by weight of toluene as a monomer mixture were added to the mixed solution to prepare an aqueous suspension. Next, the temperature of the aqueous suspension was raised to 80°C to initiate polymerization, i.e., the initiation step was performed. After 1 hour and 45 minutes from the start of polymerization (after the initiation step), the polymerization conversion rate was measured and the result was 40% to 50%. After 1 hour and 45 minutes had passed from the start of polymerization (after the initiation step), 0.12 parts by weight of tricalcium phosphate as the second poorly water-soluble inorganic salt was added to the reaction mixture (aqueous suspension) to perform an adding step.
然后，进一步经过2小时35分钟后，将作为增塑剂的环己烷1.5重量份及作为发泡剂的富正丁烷(富正丁烷中的正丁烷与异丁烷的重量比(正丁烷/异丁烷)为70/30)9重量份投入到水性悬浮液中。然后，将水性悬浮液的温度升温至101℃。接着，将水性悬浮液的温度在101℃下保持10小时，由此进行共聚以及发泡剂对共聚物的浸渗(共聚工序和发泡剂浸渗工序)。然后，将水性悬浮液冷却。在水性悬浮液冷却后，通过对得到的产物进行洗涤、脱水和干燥，从而得到发泡性甲基丙烯酸甲酯系树脂颗粒。Then, after a further 2 hours and 35 minutes, 1.5 parts by weight of cyclohexane as a plasticizer and 9 parts by weight of rich n-butane (the weight ratio of n-butane to isobutane in the rich n-butane (n-butane/isobutane) is 70/30) as a foaming agent are added to the aqueous suspension. Then, the temperature of the aqueous suspension is raised to 101°C. Next, the temperature of the aqueous suspension is maintained at 101°C for 10 hours, thereby performing copolymerization and impregnation of the copolymer with the foaming agent (copolymerization step and foaming agent impregnation step). Then, the aqueous suspension is cooled. After the aqueous suspension is cooled, the obtained product is washed, dehydrated and dried to obtain foamable methyl methacrylate resin particles.
将得到的发泡性甲基丙烯酸甲酯系树脂颗粒使用网眼0.235mm和0.600mm的筛进行筛分。通过该操作，采集粒径0.235mm～0.600mm的发泡性甲基丙烯酸甲酯系树脂颗粒。然后，将作为脂肪酸金属盐的硬脂酸锌0.40重量份、作为熔接促进剂的氢化蓖麻油0.05重量份涂布于发泡性甲基丙烯酸甲酯系树脂颗粒的表面。The obtained expandable methyl methacrylate resin particles were sieved using sieves with mesh sizes of 0.235 mm and 0.600 mm. By this operation, expandable methyl methacrylate resin particles with a particle size of 0.235 mm to 0.600 mm were collected. Then, 0.40 parts by weight of zinc stearate as a fatty acid metal salt and 0.05 parts by weight of hydrogenated castor oil as a welding accelerator were applied to the surface of the expandable methyl methacrylate resin particles.
按照上述方法，对各评价项目(发泡性甲基丙烯酸甲酯系树脂颗粒的体积平均粒径、峰顶粒径、均匀性、发泡性和填充性、以及甲基丙烯酸甲酯系树脂发泡成型体的表面美观性)进行评价。将评价结果示于表1。The evaluation results are shown in Table 1.
(实施例2)(Example 2)
将使用的单体混合物变更为甲基丙烯酸甲酯96.5重量份及丙烯酸丁酯3.5重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the monomer mixture used was changed to 96.5 parts by weight of methyl methacrylate and 3.5 parts by weight of butyl acrylate to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(实施例3)(Example 3)
将使用的单体混合物变更为甲基丙烯酸甲酯97.5重量份及丙烯酸丁酯2.5重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the monomer mixture used was changed to 97.5 parts by weight of methyl methacrylate and 2.5 parts by weight of butyl acrylate to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(实施例4)(Example 4)
将使用的单体混合物变更为甲基丙烯酸甲酯97.5重量份及丙烯酸丁酯2.5重量份，并且将使用的正十二烷基硫醇变更为0.340重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was performed except that the monomer mixture used was changed to 97.5 parts by weight of methyl methacrylate and 2.5 parts by weight of butyl acrylate, and the n-dodecyl mercaptan used was changed to 0.340 parts by weight, to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(实施例5)(Example 5)
将使用的正十二烷基硫醇变更为0.275重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the amount of n-dodecyl mercaptan used was changed to 0.275 parts by weight to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(实施例6)(Example 6)
将使用的正十二烷基硫醇变更为0.340重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。Except that the amount of n-dodecyl mercaptan used was changed to 0.340 parts by weight, the same operation as in Example 1 was carried out to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例1)(Comparative Example 1)
将使用的正十二烷基硫醇变更为0.240重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。Except that the amount of n-dodecyl mercaptan used was changed to 0.240 parts by weight, the same operation as in Example 1 was carried out to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例2)(Comparative Example 2)
将使用的作为第一水难溶性无机盐的磷酸三钙变更为0.15重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the amount of tricalcium phosphate used as the first poorly water-soluble inorganic salt was changed to 0.15 parts by weight to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例3)(Comparative Example 3)
将使用的单体混合物变更为甲基丙烯酸甲酯97.5重量份及丙烯酸丁酯2.5重量份，并且将使用的正十二烷基硫醇变更为0.265重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was performed except that the monomer mixture used was changed to 97.5 parts by weight of methyl methacrylate and 2.5 parts by weight of butyl acrylate, and the n-dodecyl mercaptan used was changed to 0.265 parts by weight, to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例4)(Comparative Example 4)
将所使用的作为第一水难溶性无机盐的第三磷酸钙变更为0.15重量份，并且将用于筛分发泡性甲基丙烯酸甲酯系树脂颗粒的筛的网眼变更为0.50mm～1.40mm，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was performed except that the third calcium phosphate used as the first poorly water-soluble inorganic salt was changed to 0.15 parts by weight and the mesh size of the sieve used to sieve the foamable methyl methacrylate resin particles was changed to 0.50 mm to 1.40 mm, thereby obtaining foamable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例5)(Comparative Example 5)
将使用的单体混合物变更为甲基丙烯酸甲酯91.5重量份及丙烯酸丁酯8.5重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the monomer mixture used was changed to 91.5 parts by weight of methyl methacrylate and 8.5 parts by weight of butyl acrylate to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例6)(Comparative Example 6)
将使用的单体混合物变更为甲基丙烯酸甲酯98.5重量份及丙烯酸丁酯1.5重量份，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。The same operation as in Example 1 was carried out except that the monomer mixture used was changed to 98.5 parts by weight of methyl methacrylate and 1.5 parts by weight of butyl acrylate to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
(比较例7)(Comparative Example 7)
使用丙烯酸甲酯代替丙烯酸丁酯，除此以外，进行与实施例1相同的操作，得到发泡性甲基丙烯酸甲酯系树脂颗粒。将各评价项目以与实施例1相同的方法进行评价。将评价结果示于表1。Except that methyl acrylate was used instead of butyl acrylate, the same operation as in Example 1 was carried out to obtain expandable methyl methacrylate resin particles. Each evaluation item was evaluated by the same method as in Example 1. The evaluation results are shown in Table 1.
(结果)(result)
由表1所示可知，实施例1～实施例6中，“均匀性”、“发泡性”及“填充性”的评价高，由此，“表面美观性”的评价也高。As shown in Table 1, in Examples 1 to 6, the evaluations of "uniformity", "foamability" and "filling property" were high, and therefore, the evaluation of "surface aesthetics" was also high.
[表1][Table 1]
产业上的可利用性Industrial Applicability
根据本发明的一个实施方式，能够提供一种可提供表面美观性优异的甲基丙烯酸甲酯系树脂发泡成型体的发泡性甲基丙烯酸甲酯系树脂颗粒。因此，本发明的一个实施方式可以适合用作通过整模法进行金属铸造时的消失模。According to one embodiment of the present invention, expandable methyl methacrylate resin particles that can provide a methyl methacrylate resin foam molded product having excellent surface appearance can be provided. Therefore, one embodiment of the present invention can be suitably used as a lost pattern in metal casting by a solid mold method.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2022054289 | 2022-03-29 | ||
| JP2022-054289 | 2022-03-29 | ||
| PCT/JP2023/010704WO2023189759A1 (en) | 2022-03-29 | 2023-03-17 | Expandable particles of methyl-methacrylate-based resin, expanded particles of methyl-methacrylate-based resin, molded foam of methyl-methacrylate-based resin, and evaporative pattern |
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| CN118525047Atrue CN118525047A (en) | 2024-08-20 |
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|---|---|---|---|
| CN202380016464.9APendingCN118525047A (en) | 2022-03-29 | 2023-03-17 | Expandable methyl methacrylate resin particles, and process for producing the same methyl methacrylate resin foam molded article and lost foam |
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| JP (1) | JPWO2023189759A1 (en) |
| CN (1) | CN118525047A (en) |
| WO (1) | WO2023189759A1 (en) |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP7568529B2 (en)* | 2021-01-28 | 2024-10-16 | 積水化成品工業株式会社 | Expandable styrene resin particles, pre-expanded styrene resin particles, and styrene resin foamed molded product |
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| JP3637785B2 (en)* | 1998-09-16 | 2005-04-13 | 住友化学株式会社 | Method for producing expandable methyl methacrylate resin particles |
| JP6225781B2 (en)* | 2014-03-25 | 2017-11-08 | 株式会社ジェイエスピー | Foamable acrylic resin particles, acrylic resin foam particles, acrylic resin foam particles |
| JP2018135408A (en)* | 2017-02-20 | 2018-08-30 | 株式会社カネカ | Method for producing expandable methyl methacrylate resin particles |
| JP7148795B2 (en)* | 2018-11-26 | 2022-10-06 | 株式会社ジェイエスピー | Expandable acrylic resin particles, expanded acrylic resin particles, expanded acrylic resin particles |
| EP4130064A4 (en)* | 2020-03-30 | 2024-04-03 | Kaneka Corporation | Expandable methyl-methacrylate-based resin particles, methyl-methacrylate-based expanded particles, methyl-methacrylate-based molded foam, and evaporative pattern |
| JPWO2022004692A1 (en)* | 2020-06-30 | 2022-01-06 |
| Publication number | Publication date |
|---|---|
| JPWO2023189759A1 (en) | 2023-10-05 |
| WO2023189759A1 (en) | 2023-10-05 |
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| PB01 | Publication | ||
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