CN114290782A - Biaxially oriented polypropylene film for epoxy resin curing and preparation method thereof - Google Patents

Abstract

The invention relates to a biaxially oriented polypropylene film for epoxy resin curing and a preparation method thereof. The utility model provides a biaxially oriented polypropylene film for epoxy resin curing, includes one deck supporting layer and two-layer from the type layer, wherein two-layer from the type layer sets up respectively in the both sides of supporting layer, from the type layer including polymethylpentene copolymer, polymethylpentene copolymer is 4-methyl 1-pentene olefin copolymer as the basis, from type layer surface tension < 29mN/m, still disclose this biaxially oriented polypropylene film for epoxy resin curing simultaneously preparation method. The biaxially oriented polypropylene film for curing epoxy resin has the advantage of easy peeling on the surface of the cured epoxy resin, and effectively solves the problem of residue on the surface of the cured epoxy resin.

Description

Biaxially oriented polypropylene film for epoxy resin curing and preparation method thereof

Technical Field

The invention relates to a biaxially oriented polypropylene film for epoxy resin curing and a preparation method thereof.

Background

The common circuit board is generally composed of epoxy resin, glass fiber and copper sheet circuit, in order to improve the mechanical property of the circuit board, the epoxy resin needs to be cured under the conditions of high temperature and high pressure, the curing temperature is generally 140-. For production efficiency, the epoxy resin prepregs with 200-600 layers are generally cured together, and in order to prevent the epoxy resin prepregs from being stuck together during curing, a spacer material is generally added between each layer of epoxy resin prepregs.

The isolating material can be selected from kraft paper or polyethylene terephthalate film coated with silicone oil, but the coated silicone oil is often difficult to completely cure, so that micromolecule silicone oil exists on the isolating material, and the silicone oil is easy to transfer to the surface of the circuit board in the using process, so that the normal operation of the circuit is influenced.

At present, a biaxially oriented polypropylene film is adopted in the industry to replace kraft paper or polyethylene terephthalate film coated with silicone oil, but because the surface tension of the biaxially oriented polypropylene film is large, and the surface of the film has static lines due to static electricity, and the surface tension of the static lines is increased, the bonding force between the film and the cured epoxy resin is large, and the film is difficult to peel off from the surface of the cured epoxy resin; the aging of the film after high temperature and high pressure can cause the reduction of the mechanical property of the film, so the film can be damaged and remained on the surface of the cured epoxy resin in the stripping process; therefore, the film needs to be torn off manually according to the residual position, so that the workload of workers is increased, the production efficiency of a factory is reduced, and the production cost of an enterprise is increased.

Disclosure of Invention

Based on the above, the present invention aims to provide a biaxially oriented polypropylene film for epoxy resin curing, which reduces the bonding force between the biaxially oriented polypropylene film and the cured epoxy resin, and effectively solves the problem that the film is difficult to peel off from the cured epoxy resin surface and even remains on the cured epoxy resin surface due to the excessive bonding force between the biaxially oriented polypropylene film and the cured epoxy resin surface in the conventional biaxially oriented polypropylene film.

The biaxially oriented polypropylene film for epoxy resin curing comprises a supporting layer and two release layers, wherein the two release layers are respectively arranged on two sides of the supporting layer, the release layers comprise polymethylpentene copolymer, the polymethylpentene copolymer is olefin copolymer based on 4-methyl-1-pentene, and the surface tension of the release layers is less than 29 mN/m.

According to the biaxially oriented polypropylene film for curing epoxy resin, the polymethylpentene copolymer layer with relatively small surface tension and good heat resistance is adopted on the surface, so that the bonding force between the film and the cured epoxy resin sheet is reduced, the film is favorably stripped from the surface of the cured epoxy resin, and the problem of residual epoxy resin of the film after curing is solved.

Further, the surface tension of the polymethylpentene copolymer is 24mN/m, the polymethylpentene copolymer is formed by copolymerizing 4-methyl-1-pentene and one or more of ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene and decene, and the content of the 4-methyl-1-pentene in the polymethylpentene copolymer is 95-100 wt%. The low surface tension of the polymethylpentene copolymer is utilized to reduce the binding force between the film and the epoxy resin, so that the film is easier to peel off after the epoxy resin is cured; the better heat resistance of the polymethylpentene copolymer is utilized, so that the film still has better physical properties after high temperature and high pressure, and the phenomenon that the film is damaged and cannot be transferred cleanly is improved. In particular toTPX produced by three-well chemistry^TMPolymethylpentene copolymer, TPX^TMThe polymethylpentene copolymer has a specific molecular structure, and is a crystalline olefin resin, TPX^TMThe polymethylpentene copolymer material is transparent, has excellent performances of heat resistance, light transmittance, air permeability, low density characteristic, easy stripping property, excellent electrical insulation property, chemical resistance, steaming resistance and the like, does not contain halogen, is clean and environment-friendly, and has the surface tension of 24 mN/m. The release layer is made of polymethylpentene copolymer, so that the surface tension of the release layer is reduced, the bonding force between the film and the cured epoxy resin is reduced, and a better stripping effect can be achieved after the epoxy resin is cured.

Further, the thickness of the release layer is 0.8-1 μm. The surface tension of polypropylene is generally 29-31mN/m, while the surface tension of polymethylpentene copolymer is only 24mN/m, which is 5-7mN/m less than that of polypropylene, but the polymethylpentene copolymer is expensive at present. When the casting process and the blow molding process are adopted, the thickness of the polymethylpentene copolymer layer cannot be lower than 3-5 μm, and if the thickness is lower than 3-5 μm, the thickness of the polymethylpentene copolymer layer is adjusted to 1 μm, so that the complete coverage of the polymethylpentene copolymer on the surface layer of the film is difficult to realize, and the performance defect of the local position of the film is caused, thereby generating a poor product. The invention adopts a bidirectional stretching production process, introduces the polymethylpentene copolymer on two surfaces of the film, can make the thickness of the polymethylpentene copolymer reach 1 mu m, when the thick sheet is formed, the thickness of the polymethylpentene copolymer reaches about 40 mu m, ensures that the surface of the thick sheet is completely covered with the polymethylpentene copolymer layer, and reduces the usage amount of the expensive polymethylpentene copolymer and the production cost of the film by stretching about 4-6 times in the longitudinal direction and stretching about 7-10 times in the transverse direction, and reducing the thickness of the polymethylpentene copolymer layer to 0.8-1 mu m.

Further, the support layer includes an antistatic agent comprising one or more of glycerol monostearate, ethoxylated alkylamine, and diethanolamine. The percentage of the antistatic agent in the support layer is 0.1-1 wt%. The antistatic agent in the supporting layer can migrate to the surface of the release layer through diffusion, so that the generation of static electricity on the surface of the film is reduced, and the local surface tension of the film is prevented from being increased. If the content of the antistatic agent is less than 0.1 wt%, the antistatic effect is poor, and the surface of the film still has a problem of large static electricity, and if the content of the antistatic agent is more than 1 wt%, the migration of the antistatic agent is easily caused. If the antistatic agent is not added, static accumulation easily causes static lines on the surface of the film in the film production process, the surface tension of the positions of the static lines is higher than that of other positions, and the static lines need to be detected by using corona liquid, so the static lines are avoided by adding the antistatic agent.

Further, the release layer also comprises an anti-blocking agent, and the anti-blocking agent comprises one or more of silicon dioxide, polymethyl methacrylate and polysiloxane. The anti-blocking agent is added to improve the film unwinding performance and prevent the film unwinding difficulty. The anti-blocking agent preferably has an average particle size of 4 to 5 μm, and if the particle size is too small, the anti-blocking effect is not good, and if the particle size is too large, the anti-blocking agent is easily released from the release layer.

Further, the release layer also comprises a delustering filler, the delustering filler comprises an inorganic filler or an organic filler, the inorganic filler comprises one or more of silicon dioxide, calcium carbonate and titanium dioxide, and the average particle size of the inorganic filler is 4-5 μm; the organic filler comprises one or two of polymethyl methacrylate or polystyrene, and the average particle size of the organic filler is 4-5 mu m. The extinction filler can endow the uneven surface of the film with an extinction effect, so that the surface of the cured epoxy resin sheet has a higher-grade visual effect.

Further, the support layer comprises isotactic polypropylene, the content of the isotactic polypropylene is 90-100 wt%, and the isotacticity of the isotactic polypropylene is 90-99%. In the isotacticity range, the melting point of the high isotactic polypropylene is higher than that of the common polypropylene, so that the support layer can be endowed with better heat resistance.

Further, the support layer also comprises 5-20 wt% of heat-resistant filler, the heat-resistant filler comprises inorganic filler or organic filler, the inorganic filler comprises one or more of calcium carbonate, titanium dioxide, kaolin, talcum powder, aluminum hydroxide and magnesium hydroxide, and the average grain diameter of the inorganic filler is less than or equal to 5 mu m; the organic filler comprises one or more of polycarbonate, polyethylene terephthalate and polybutylene terephthalate. The addition of the heat-resistant filler endows the supporting layer with better heat resistance, solves the problem that the mechanical property of the supporting layer is reduced too much after high temperature and high pressure, and is beneficial to stripping the film from the surface of the cured epoxy resin so as not to be easily damaged. In addition, the heat-resistant filler can endow the supporting layer with a certain cavitation degree and a pearl effect, so that the cost is reduced.

Furthermore, the biaxially oriented polypropylene film for epoxy resin curing also comprises an adhesive layer, wherein the adhesive layer is arranged between the release layer and the support layer, the adhesive layer is a polymethylpentene-propylene copolymer, and the content of propylene in the polymethylpentene-propylene copolymer is 5-30 wt%. Wherein one side of bond line is connected with the one side from the type layer, and the another side of bond line is connected with the one side of supporting layer, and the bond line setting is between type layer and supporting layer, further improves the cohesion between type layer and the supporting layer, does benefit to improve the phenomenon that the layering appears from type layer and supporting layer in the use.

The invention also provides a preparation method of any one of the biaxially oriented polypropylene films for epoxy resin curing, which comprises the following steps: the screened raw materials are premixed according to a designed formula, uniformly stirred, respectively fed into each layer of extruder after being weighed and calculated in a feeding proportion to be processed into uniformly plasticized melt, the melt is transported through a pipeline and filtered by a filter, and is distributed through a flow channel and a die head, then is cast into a thick sheet through a tape casting chilling process, the thick sheet is subjected to bidirectional stretching to form a thin film, the bidirectional stretching process can be divided into longitudinal and transverse step-by-step stretching or longitudinal and transverse synchronous stretching, the thin film is subjected to shaping, cooling, trimming at two sides, traction thickness measurement, rolling into a mother roll, the mother roll is subjected to aging treatment, and finally is cut into a thin film finished product.

For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 is a cross-sectional view of a first structure of the present invention;

FIG. 2 is a cross-sectional structural view of a second structure of the present invention;

FIG. 3 is a cross-sectional view of the present invention as applied to curing an epoxy circuit board;

FIG. 4 is a schematic view of a biaxial stretching process of the film manufacturing method of the present invention.

Detailed Description

Fig. 1 shows a first structure of a biaxially oriented polypropylene film for curing epoxy resin according to the present invention, the first structure is a three-layer structure, and includes tworelease layers 1 and a supportinglayer 2, the tworelease layers 1 are respectively disposed on the upper side and the lower side of the supportinglayer 2, and the structure is subjected to interlayer lamination by coextrusion.

Fig. 2 shows a second structure of the biaxially oriented polypropylene film for curing epoxy resin of the present invention, the second structure is a five-layer structure, and includes tworelease layers 1, twobonding layers 3 and a supportinglayer 2, thebonding layers 3 are respectively disposed between the tworelease layers 1 and the supportinglayer 2, and the purpose of thebonding layers 3 is to improve the bonding strength between therelease layers 1 and the supportinglayer 2 and reduce the probability of separation between therelease layers 1 and the supportinglayer 2 when the film is laminated under high temperature and high pressure conditions.

Therelease layer 1 is a polymethylpentene copolymer or a blend containing the polymethylpentene copolymer, an anti-blocking agent and an antioxidant, the polymethylpentene copolymer is formed by copolymerizing 4-methyl-1-pentene and one or more of ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene and decene, wherein the content of the 4-methyl-1-pentene in the polymethylpentene copolymer is 95-100 wt%; the anti-blocking agent is silicon dioxide (SiO)₂) Polymethyl methacrylate (PMMA), Polysiloxane (PDMS), and the like; the antioxidant is common antioxidant with the grades of 1010, 1076, 168, 618 and the like. Therelease layer 1 can be formed by adding a matting filler to the surface to achieve a surface matting effect, wherein the matting filler comprises common inorganic fillers such as silica, calcium carbonate, titanium dioxide and the like, and organic fillers such as polymethyl methacrylate, preferably silica. Because the price of the polymethylpentene copolymer is highThe thickness of therelease layer 1 is generally less than or equal to 5 μm, preferably less than or equal to 3 μm, and more preferably less than or equal to 1 μm, and the average particle size of the filler is adjusted according to the thickness of therelease layer 1, and the average particle size of the inorganic filler corresponding to the thickness of therelease layer 1 is 10-15 μm, 6-10 μm, and 4-5 μm, respectively, because the particle size of the matting filler in production does not match the thickness of the surface layer of the film, which may cause the problem of filler shedding and affect the matting effect.

Thesupport layer 2 mainly adopts polypropylene as a main material, can provide excellent physical properties for the film, and is generally a mixture consisting of isotactic polypropylene and one or more of an antistatic agent and an antioxidant, wherein the content of the isotactic polypropylene is 90-100 wt%, the isotacticity of the isotactic polypropylene is 90-99%, the preferred isotacticity is 95-99%, and the further preferred isotacticity is 98-99%. At 98-99% isotacticity, the melting point of isotactic polypropylene is 168 ℃ while the melting point of ordinary polypropylene is 163-164 ℃, which imparts more excellent heat resistance to thesupport layer 2 of the present invention. In order to further improve the bonding fastness of therelease layer 1 and thesupport layer 2 and effectively improve the layering phenomenon of therelease layer 1 and thesupport layer 2 in the use process, anadhesive layer 3 can be arranged between therelease layer 1 and thesupport layer 2, theadhesive layer 3 adopts polymethylpentene-propylene copolymer, and the content of propylene in the polymethylpentene-propylene copolymer is 5-30 wt%.

In order to improve the heat resistance of the biaxially oriented polypropylene film of the present invention, 5 to 20 wt% of an inorganic filler may be added to thesupport layer 2 to improve the heat resistance of the film, wherein the inorganic filler comprises: calcium carbonate, titanium dioxide, kaolin, talc, aluminum hydroxide, magnesium hydroxide and the like, and calcium carbonate and titanium dioxide are preferred as the inorganic filler, and calcium carbonate is more preferred in view of price.

The application the biaxially oriented polypropylene film for epoxy resin curing is mainly applied to the isolation between epoxy resin prepreg layers in the epoxy resin production process, is favorable for peeling off the film from the cured epoxy resin surface along with the epoxy resin prepreg after curing and forming under the high-temperature and high-pressure environment, and improves the residual problem of the film on the cured epoxy resin.

The specific curing process of the epoxy resin circuit board comprises the following steps: and (2) isolating the layers of the multi-layer epoxy resin prepreg with the copper foil circuit by using the biaxially oriented polypropylene film, then laminating the prepreg by using high-temperature high-pressure laminating equipment, and stripping the film from the surface of the epoxy resin after the semi-cured epoxy resin is completely cured and cooled to normal temperature to finally obtain the epoxy resin circuit board.

According to fig. 3, in the epoxy resin circuit board curing process, the biaxially orientedpolypropylene film 5 of the present invention is placed between theprepregs 4 of the multilayer epoxy resin circuit board, the number of layers of the epoxy resin electrical prepregs generally placed is 200-600, and then the two layers are cured and formed together at high temperature and high pressure, wherein 6 in the schematic diagram indicates the number of layers of the omitted epoxy resin prepregs and the biaxially oriented polypropylene film of the present invention.

As shown in fig. 4, the process flow of the thin film preparation method of the present invention is as follows:

a is raw materials (including main raw materials, modified materials and additive master batch), B is a melt, C is a thick sheet, D is a film mother roll, E is a finished product, F is an extruding process of an extruder, G is a quenching process, H is a biaxial stretching process, I is a mother roll winding process, and J is an aging slitting process.

The specific process comprises the following steps: the method comprises the following steps of premixing screened raw materials A (including main raw materials, modified materials and additive master batches) according to a designed formula, uniformly stirring, feeding the raw materials into each extruder after weighing and calculating the input proportion, plasticizing the raw materials into a melt B in an extrusion process F, conveying the melt through a pipeline, filtering the melt through a filter, distributing the melt to a die head through a flow channel for coextrusion, then carrying out chilling process G on the melt B through a chill roll to form a thick sheet C, and carrying out biaxial stretching process H on the thick sheet C to form a film, wherein the biaxial stretching process can be a step double-drawing process of longitudinal stretching and transverse stretching, or a synchronous double-drawing process of longitudinal and transverse synchronous stretching. And (3) cooling the film, trimming two sides of the film, drawing and measuring thickness, and rolling the mother roll I to obtain a film mother roll D, and performing aging slitting J on the film mother roll D to finally form a film finished product E.

The temperature of the extruder, the flow channel, the pipeline, the filter and the die head used in the method is controlled to be 230-260 ℃, the quenching temperature is 25-40 ℃, in the step-by-step drawing process, the process temperature of longitudinal and transverse drawing is 140-180 ℃, the longitudinal drawing ratio is 4.0-6.0 times, and the transverse drawing ratio is 7.0-10.0 times; in the synchronous stretching process, the process temperature of longitudinal stretching and transverse stretching is 150-. After the biaxial stretching process, the film can be cooled at room temperature, trimmed at two sides and measured in thickness, and finally wound into a mother roll.

Description 1: the criteria according to which the product properties were tested in the following examples are given in the table below:

description 2: film peel test method: after the epoxy resin prepreg and the biaxially oriented polypropylene film are cured at high temperature and high pressure, the film is peeled from the surface of the epoxy resin by hands, and the film is observed by human eyes to judge whether the film is remained on the surface of the epoxy resin after peeling, if no film is remained on the surface of the epoxy resin, the evaluation is qualified, and if the film is remained on the surface of the epoxy resin, the evaluation is unqualified.

Description 3: the percentages or percentages of the formulations described in the following examples are by weight.

Example 1

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 mu m, the thickness of therelease layer 1 is 1 mu m, and the thickness of the supportinglayer 2 is 48 mu m.

The preparation method is a step-by-step biaxial stretching flat membrane method, and the specific process comprises the following steps: the method comprises the following steps of premixing screened raw materials A (including main raw materials, modified materials and additive master batches) according to a designed formula, uniformly stirring, feeding the raw materials into each extruder after weighing and calculating the input proportion, plasticizing the raw materials into a melt B in an extrusion process F, conveying the melt through a pipeline, filtering the melt through a filter, distributing the melt to a die head through a flow channel for coextrusion, then carrying out chilling process G on the melt B through a chill roll to form a thick sheet C, and carrying out biaxial stretching process H on the thick sheet C to form a film, wherein the biaxial stretching process is a step-by-step biaxial stretching process of longitudinal stretching and transverse stretching. And (3) shaping, cooling, trimming two sides of the film, drawing and measuring thickness, and rolling the mother roll I to obtain a film mother roll D, and performing aging slitting J on the film mother roll D to finally form a film finished product E.

The production equipment is a flat film step biaxial stretching polypropylene production line provided by Brukner (BRUECKNER) of Germany, a screw of a main extruder (a support layer 2) is a single-screw extruder with the diameter of 150mm and the length-diameter ratio of 33:1, and an auxiliary extruder (a release layer 1) is a single-screw extruder with the screw diameter of 120mm and the length-diameter ratio of 30: 1. The temperature of the extruder is 240 ℃ except for the feeding section, the temperature of each section of the filter, the runner and the die head is 240 ℃, and the temperature of the quenching (tape casting) is 45 ℃; the corresponding temperature of a preheating zone, a stretching zone and a shaping zone through which the longitudinalstretching release layer 1 passes is 145 ℃, and the stretching ratio is 4.8; transverse stretching temperature: the preheating zone is 180 ℃, the stretching zone is 160 ℃, the setting zone is 176 ℃, and the stretching ratio is 8; the production speed was 400 m/min.

Example 2

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 95 wt% polymethylPentene copolymer (melt index 4.6g/10min, 230 ℃, 2.16Kg), 5% by weight of synthetic silica, wherein the average particle size of the synthetic silica is 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3.0g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of ethoxylated alkylamine.

The total thickness of the prepared product is 50 mu m, the thickness of therelease layer 1 is 0.8 mu m, and the thickness of the supportinglayer 2 is 48.4 mu m.

The preparation method was the same as that of example 1 except that the stretching ratio of the transverse stretching was 9.

Example 3

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 90 wt% of polymethylpentene copolymer (melt index 4.6g/10min, 230 ℃, 2.16Kg), 10 wt% of synthetic silica, wherein the synthetic silica has an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3.0g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of ethoxylated alkylamine.

The total thickness of the prepared product is 50 mu m, the thickness of therelease layer 1 is 0.8 mu m, and the thickness of the supportinglayer 2 is 48.4 mu m.

The preparation method was the same as that of example 1 except that the stretching ratio of the transverse stretching was 9.

Example 4

The film of this embodiment includes two-layer fromtype layer 1, two-layer bond line 3 and onedeck supporting layer 2, and two-layer bond line 3 sets up respectively in the both sides of supportinglayer 2, and two-layer fromtype layer 1 sets up respectively in one side of two-layer bond line 3, makes the both sides ofbond line 3 be supportinglayer 2 and fromtype layer 1 respectively, and concrete structure is as shown in fig. 2.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

Theadhesive layer 3 comprises the following components: 100 wt% of a polymethylpentene-propylene copolymer (melt index of 10g/10min, 230 ℃, 2.16Kg), the content of propylene in the polymethylpentene-propylene copolymer being 5 to 30 wt%. .

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, the thickness of thebonding layer 3 is 1 micrometer, and the thickness of the supportinglayer 2 is 46 micrometers.

The preparation process was the same as in example 1, except that theadhesive layer 3 used the same auxiliary extruder as therelease layer 1, and the process temperature of the auxiliary extruder for theadhesive layer 3 was the same as that of the auxiliary extruder for therelease layer 1.

Example 5

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (polymethylpentene)The content of 4-methyl-1-pentene in the copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 92.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃ C., 2.16Kg), 7 wt% of calcium carbonate (average particle diameter 1.1 μm), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, and the thickness of the supportinglayer 2 is 48 micrometers.

The preparation method is the same as that of example 1.

Example 6

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 92.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃ C., 2.16Kg), 7 wt% of polybutylene terephthalate, 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, and the thickness of the supportinglayer 2 is 48 micrometers.

The preparation method is the same as that of example 1.

The stepwise biaxially oriented polypropylene film produced by the structure, composition and preparation method described in examples 1 to 6 has a simple structure and is beneficial to the production and popularization of products.

Example 7

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, and the thickness of the supportinglayer 2 is 48 micrometers.

The preparation method is a synchronous biaxial stretching flat membrane method, and the specific process comprises the following steps: the screened raw materials A (including main raw materials, modified materials and additive master batches) are premixed according to a design formula, uniformly stirred, fed into each extruder after being weighed and calculated according to the input proportion, plasticized into a melt B in an extrusion process F, the melt is conveyed through a pipeline and filtered by a filter, and distributed to a die head through a flow channel for coextrusion, then the melt B is quenched through a chill roll to form a thick sheet C, the thick sheet C forms a thin film through a biaxial stretching process H, and the biaxial stretching process adopts a synchronous biaxial stretching process of longitudinal and transverse synchronous stretching. And (3) shaping, cooling, trimming two sides of the film, drawing and measuring thickness, and rolling the mother roll I to obtain a film mother roll D, and performing aging slitting J on the film mother roll D to finally form a film finished product E. The production equipment is a flat-film-method biaxially oriented polypropylene production Line (LISIM) provided by Brukner (BRUECKNER) of Germany, a screw of a main extruder (a support layer 2) is a single-screw extruder with the diameter of 169mm and the length-diameter ratio of 32:1, and an auxiliary extruder (a release layer 1) is a single-screw extruder with the screw diameter of 135mm and the length-diameter ratio of 33: 1. The temperature of the extruder is 240 ℃ except for the feeding section, the temperature of each section of the filter, the runner and the die head is 240 ℃, and the temperature of the quenching (tape casting) is 40 ℃; the infrared preheating temperature is 500 ℃ in each zone, and the longitudinal and transverse stretching temperature is as follows: preheating zone 175 deg.C, stretching zone 158 deg.C, shaping zone 175 deg.C, and longitudinal and transverse stretching ratio of 5 × 9; the production speed was 330 m/min.

Example 8

The film of the embodiment comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of a polymethylpentene copolymer (melt index of 4.6g/10min, 230 ℃ C., 2.16Kg), 0.2 wt% of synthetic silica having an average particle diameter of 4 μm. The polymethylpentene copolymer is TPX produced using Trill chemistry^TMPolymethylpentene copolymer (the content of 4-methyl-1-pentene in the polymethylpentene copolymer is 95 to 100% by weight, and the surface tension thereof is 24 mN/m).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 1g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, and the thickness of the supportinglayer 2 is 48 micrometers.

The preparation method is a bubble tube method, and comprises the following specific processes: the screened raw materials A (including main raw materials, modified materials and additive master batches) are premixed according to a design formula, uniformly stirred, fed into each extruder after being weighed and calculated according to the input proportion, plasticized into a melt B in an extrusion process F, and the melt B forms a film through a blowing process K. And (3) cooling the film, trimming two sides of the film, drawing and measuring thickness, and rolling the mother roll I to obtain a film mother roll D, and performing aging slitting J on the film mother roll D to finally form a film finished product E.

The equipment used in the method is a bubble tube method biaxial oriented film production line provided by the company Reinforhauser (Reinforhauser) Germany, a main extruder screw is a single screw extruder with the diameter of 150mm and the length-diameter ratio of 33:1, and an auxiliary extruder is a single screw extruder with the screw diameter of 120mm and the length-diameter ratio of 30: 1. The temperature of an extruder is 250 ℃, the temperature of a filter is 250 ℃ and the temperature of a die head is 250 ℃; the quenching temperature is 20 ℃, the temperature of the primary tube film preheating oven is controlled to be 350 ℃, the temperature in the transverse blowing oven is controlled to be 420 ℃, the roller temperature corresponding to therelease layer 1 is controlled to be 145 ℃, the longitudinal stretching ratio is 5.6, and the transverse stretching ratio is 8.0.

Comparative example 1

The film of the comparative example comprises tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively arranged on two sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of synthetic silica, wherein the average particle size of the synthetic silica is 4 μm.

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 micrometers, the thickness of therelease layer 1 is 1 micrometer, and the thickness of the supportinglayer 2 is 48 micrometers.

The preparation method is the same as that of example 1.

Comparative example 2

The film of the present comparative example includes tworelease layers 1 and asupport layer 2, wherein the tworelease layers 1 are respectively disposed on both sides of thesupport layer 2, and the specific structure is shown in fig. 1.

Therelease layer 1 comprises the following components: 60% by weight of high-density polyethylene (density 0.952g/cm3, melt index 9.0g/10min, 190 ℃ C., 21.6Kg), 40% by weight of propylene-ethylene copolymer (melt index 7.0g/10min, 230 ℃ C., 2.16 Kg).

Thesupport layer 2 comprises the following components: 99.8 wt% of homopolypropylene (isotacticity 98%, melt index 3g/10min, 230 ℃, 2.16Kg), 0.2 wt% of glycerol monostearate.

The total thickness of the prepared product is 50 mu m, the thickness of therelease layer 1 is 1.8 mu m, and the thickness of the supportinglayer 2 is 46.4 mu m.

The preparation method is the same as that of example 1.

The results of the property test of the biaxially oriented polypropylene film produced in examples 1 to 8 and comparative examples 1 to 2 are as follows:

it can be seen from comparative examples 1 and 2 that when polypropylene or high density polyethylene is used as therelease layer 1 and an antistatic agent is added, a small amount of film remains on the surface of the circuit board when the film is peeled, and secondary peeling is required manually, while the corresponding film peeling tests are all qualified in the embodiment using the polymethylpentene copolymer as therelease layer 1, which indicates that in the application scenario of the present application, the film remaining phenomenon when the film is peeled cannot be solved only by adding the antistatic agent, and cannot be solved by using polypropylene with similar surface tension. Comparing example 1, example 7 and example 8, it can be seen that the films described herein can be produced using a step-and-step biaxial stretching flat film process, a simultaneous biaxial stretching flat film process and a bubble tube process biaxial stretching line.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, to those skilled in the art, changes and modifications may be made without departing from the spirit of the present invention, and it is intended that the present invention encompass such changes and modifications.

Claims (10)

1. The biaxially oriented polypropylene film for epoxy resin curing is characterized in that: the release layer comprises a polymethyl pentene copolymer, the polymethyl pentene copolymer is an olefin copolymer based on 4-methyl 1-pentene, and the surface tension of the release layer is less than 29 mN/m.

2. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the surface tension of the polymethylpentene copolymer is 24mN/m, the polymethylpentene copolymer is formed by copolymerizing 4-methyl-1-pentene and one or more of ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene and decene, and the content of the 4-methyl-1-pentene in the polymethylpentene copolymer is 95-100 wt%.

3. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the thickness of the release layer is 0.8-1 μm.

4. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the support layer includes an antistatic agent comprising one or more of glycerol monostearate, an ethoxylated alkylamine, and diethanolamine.

5. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the release layer also comprises an anti-blocking agent, and the anti-blocking agent comprises one or more of silicon dioxide, polymethyl methacrylate and polysiloxane.

6. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the release layer also comprises a delustering filler, the delustering filler comprises an inorganic filler or an organic filler, the inorganic filler comprises one or more of silicon dioxide, calcium carbonate and titanium dioxide, and the average particle size of the inorganic filler is 4-5 μm; the organic filler comprises one or two of polymethyl methacrylate or polystyrene, and the average particle size of the organic filler is 4-5 mu m.

7. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the supporting layer comprises isotactic polypropylene, the content of the isotactic polypropylene is 90-100 wt%, and the isotacticity of the isotactic polypropylene is 90-99%.

8. The biaxially oriented polypropylene film for epoxy resin curing according to claim 7, wherein: the supporting layer also comprises 5-20 wt% of heat-resistant filler, the heat-resistant filler comprises inorganic filler or organic filler, the inorganic filler comprises one or more of calcium carbonate, titanium dioxide, kaolin, talcum powder, aluminum hydroxide and magnesium hydroxide, and the average grain diameter of the inorganic filler is less than or equal to 5 mu m; the organic filler includes: one or more of polycarbonate, polyethylene terephthalate and polybutylene terephthalate.

9. The biaxially oriented polypropylene film for epoxy resin curing according to claim 1, wherein: the adhesive layer is arranged between the release layer and the support layer, and is a polymethylpentene-propylene copolymer, wherein the content of propylene in the polymethylpentene-propylene copolymer is 5-30 wt%.

10. A method for producing a biaxially oriented polypropylene film for curing epoxy resins according to any one of claims 1 to 9, characterized in that: the method comprises the following steps: the screened raw materials are premixed according to a designed formula, uniformly stirred, weighed and calculated in a feeding ratio, respectively sent into each layer of extruder to be processed into uniformly plasticized melt, the melt is transported through a pipeline and filtered by a filter, and is distributed through a flow channel and a die head, then is cast into a thick sheet through a tape casting chilling process, the thick sheet is subjected to bidirectional stretching to form a thin film, the bidirectional stretching process can be divided into longitudinal and transverse step-by-step stretching or longitudinal and transverse synchronous stretching, the thin film is subjected to shaping, cooling, trimming at two sides, traction thickness measurement, collection into a mother roll, the mother roll is subjected to aging treatment, and finally is cut into a thin film finished product.

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