CN103421236A - Polypropylene composition and polypropylene blown film - Google Patents

Abstract

The invention provides a polypropylene composition for preparing a blown film. The composition comprises 100 parts of polypropylene with a melt strength greater than 0.2 N and 0.5 to 11 parts of metallocene polyethylene. According to the invention, there is no need to select co-polypropylene to carry out chemical modification (copolymerization) of the polypropylene. The metallocene polyethylene is added into the high-melt strength polypropylene to obtain the polypropylene composition, and then the polypropylene composition is used for preparing a blown film. The obtained polypropylene film is not decreased in heat resistance. On the contrary, the film is enhanced in tear strength, substantially reduced in difference between the longitudinal tear strength and the transverse tear strength, and improved in optical performance. By adding a nucleating agent into the composition containing the metallocene polyethylene and the high-melt strength polypropylene, the difference between the longitudinal tear strength and the transverse tear strength is further reduced. The polypropylene composition and the blown film provided by the invention are simple in preparation technique and low in cost.

Description

A kind of polypropene composition and polypropylene blown film

Technical field

The present invention relates to a kind of polypropene composition.Further, the present invention relates to a kind of polypropene composition of extrusion blow molding film and polypropylene film of preparation thereof of preparing.

Background technology

Polypropylene (PP) film has excellent thermotolerance, high physical strength, grease resistance and the transparency preferably, be widely used in industry and daily life, be specially adapted to that bag for cooking food, microwave food packaging, medical high temperature steaming are sterilized and large-scale heavy pack etc.

Extrusion blow molding film technique is simple, equipment is few, has cost advantage.Extrusion blow molding film accounts for 85% of all film production.But, for polypropylene film, be mainly to adopt to extrude that curtain coating is single, double produces to stretching technique for a long time.Because melt viscosity and the melt strength of common PP resin are low, be difficult to the extrusion-blown modling film forming.Along with the progress of polymerization and catalyst technology, the high bath strength acrylic resin that is applicable to extrusion-blown modling is developed in recent years.Due to melt strength and the more common PP of viscosity high a lot, therefore can be traditional produce the PP film on polyethylene blown film equipment.Extrusion-blown modling PP film cost is low, and production efficiency is high, tear strength is large, the film thickness wide ranges.

Because melt viscosity and the melt strength of common PP resin are low, be difficult to the extrusion-blown modling film forming, therefore have at present to adopt in propylene polymerization processes, to add the method for copolymerization of ethylene monomer to carry out production copolymerization PP, and take copolymerization PP as the raw material production polypropylene blown film.Due to adding of vinyl monomer, improved the toughness of film, but the difference of the vertical and horizontal tear strength of film is still very large, and causes the thermotolerance of film to decline to a great extent.In plain polypropylene, often add nucleator to improve modulus, improve the transparency, but the large problem of difference that adds the vertical and horizontal tear strength that can not solve film of nucleator.

Summary of the invention

For the deficiencies in the prior art, the invention provides a kind of polypropylene blown film for preparing the polypropene composition of blown film and utilize above-mentioned polypropene composition to prepare, with respect to prior art, use polypropene composition provided by the invention to prepare blown film, do not reducing under the stable on heating prerequisite of film, can improve the tear strength of film, the difference that reduces the vertical and horizontal tear strength and increase optical property.

According to an aspect of the present invention, the invention provides a kind of polypropene composition for the preparation of blown film, comprise that the melt strength of 100 parts is greater than 0.2 newton's polypropylene and 0.5 ~ 11 part of metallocene PE.

In above-mentioned polypropene composition, preferably comprise polypropylene and 0.5 ~ 8 part of metallocene PE of 100 parts, more preferably comprise polypropylene and 1 ~ 3 part of metallocene PE of 100 parts.

In an embodiment of above-mentioned polypropene composition, described composition comprises nucleator.Comprise the described nucleator of 0.1 ~ 0.8 part in described composition, preferably comprise the nucleator of 0.4 ~ 0.6 part.

According to a further aspect in the invention, provide a kind of polypropylene blown film, the melt strength that comprises 100 parts is greater than 0.2 newton's polypropylene and 0.5 ~ 11 part of metallocene PE.

In above-mentioned polypropylene blown film, the polypropylene that comprises 100 parts and 0.5 ~ 8 part of metallocene PE, more preferably comprise polypropylene and 1 ~ 3 part of metallocene PE of 100 parts.

In an embodiment of above-mentioned polypropylene blown film, also comprise nucleator in described film.Comprise the described nucleator of 0.1 ~ 0.8 part in described film, preferably comprise the nucleator of 0.4 ~ 0.6 part.

Above-mentioned polypropylene blown film, the tear strength of described film is more than 130N/mm, preferably, more than 140N/mm, cross direction tear strength and machine direction tear differ and are less than 24%, preferably are less than 20%, are more preferably less than 15%.

In above-mentioned polypropylene blown film, the mist degree of described film is less than 22%, and transmittance is greater than 91%, and fusing point is higher than 166 ℃.

In the present invention, described polypropylene is high melt strength, propylene, and its melt strength is more than 0.2 newton, its molecular weight distribution 3 ~ 8.Described metallocene PE is for adopting metallocene catalyst polymerisation to obtain.Commercial metallocene PE is the multipolymer of ethene and a small amount of hexene or octene normally, and melting index is at 0.4 ~ 5g/10min, and molecular weight distribution is less than 4.

In the present invention, described nucleator is polypropylene nucleater.As described in nucleator can be selected from nucleator in organic phosphate class and Dibenzalsorbierite derivatives class nucleator.The specific examples of described nucleator comprises 2,2 '-methylene-bis (4,6-di-t-butyl) phenol sodium phosphate (NA11), 1,3-2,4-bis-(3,4-dimethyl) benzylidene Sorbitol Powder (3988) and super nucleator HPN-68L.Part in the present invention refers to weight part.

The preparation method of above-mentioned polypropylene blown film, comprise that by comprising melt strength be that polypropylene more than 0.2 newton and the composition of metallocene PE mix, then extruding pelletization, blown film.

In aforesaid method, described composition comprises that the melt strength of 100 parts is greater than 0.2 newton's polypropylene and 0.5 ~ 11 metallocene PE.Preferably comprise polypropylene and 0.5 ~ 8 part of metallocene PE of 100 parts, more preferably comprise polypropylene and 1 ~ 3 part of metallocene PE of 100 parts.

In an embodiment of aforesaid method, described composition comprises nucleator.Comprise the described nucleator of 0.1 ~ 0.8 part in described composition, preferably comprise the nucleator of 0.4 ~ 0.6 part.

In a specific embodiment of aforesaid method, at described twin screw extruder mixing granulation.160 ~ 230 ℃ of described extrusion temperatures, preferably 170 ~ 220 ℃.

In a specific embodiment of aforesaid method, prepare polypropylene film on inflation film manufacturing machine, described can be the lower blowing water cold type, flat blowing cold type, can be also traditional up-draught cold type polyvinyl blow molding unit.180 ~ 230 ℃ of the temperature of described blown film, preferably 185 ~ 220 ℃.

According to the present invention, without polypropylene being carried out to chemical modification (copolymerization), metallocene PE is joined in high melt strength, propylene and obtains polypropene composition, then for the preparation of blown film, the polypropylene film obtained not only thermotolerance does not descend, and the tear strength of film is improved, the difference of its vertical and horizontal tear strength also reduces greatly, and optical property also is improved.Add nucleator in the composition that comprises metallocene PE and high melt strength, propylene, can further reduce on the contrary the difference of vertical and horizontal tear strength.According to polypropene composition provided by the invention and blown film, preparation technology is simple, and cost is low.

Embodiment

Below with embodiment, the present invention is further elaborated, but it should be understood that it does not form any limitation of the invention.

Testing method:

Melt strength: the German GOTTFERT Rheotens of company 97 type melt strength testers, extrusion mould-outlet diameter 2mm, 200 ° of C of die temperature, stretching wheel gap 0.4mm, stretching acceleration 20mm/S².The Haake torque rheometer, single screw rod, diameter is 19mm, length-to-diameter ratio is 25:1.

Film angle tear strength: according to the QB/T1130-1991 standard test.

Film Haze: according to the GB/T2410-1980 standard test.

Film transmittance: according to the GB/T2410-1980 standard test.

Film fusing point: the Diamond DSC of U.S. PerkinElmer company (N536-0022) F.T. type differential scanning calorimeter.

Embodiment 1

Take in proportion high melt strength, propylene (Zhenhai Oil-Refining ChemicalCo., Ltd., China Petro-Chemical Corp product, trade mark HMS20Z), metallocene PE (China Petrochemical Corp.'s asphalt in Shenli Refinery product, trade mark QHM23F) and nucleator (Ciba company product, trade mark NA11), concrete quantity is in Table 1, be uniformly mixed, then believe the CTE-35 twin screw extruder mixing granulation of Long Keya machinery company limited with section, each section Temperature Setting of forcing machine: 170 ℃, 180 ℃, 190 ℃, 200 ℃, 210 ℃, 215 ℃ (head).The pellet obtained is extruded blown film on the SJ-30 inflation film manufacturing machine of Lvshun, Daliang City forcing machine factory, each section Temperature Setting of inflation film manufacturing machine: 185 ℃, and 195 ℃, 210 ℃, 220 ℃, 215 ℃ (mouthful mould).Blow-up ratio is: 2.46.The film obtained carries out mechanics and optical performance test, the results are shown in Table 2.

Comparative example 1

Directly on inflation film manufacturing machine, extrude blown film with high melt strength, propylene, condition is with embodiment 1.The film performance recorded is listed in table 2.

Embodiment 2

Except Added Nucleating Agents not, all the other are with embodiment 1.The film performance recorded is listed in table 2.

Embodiment 3

Except the metallocene PE consumption changes 4 into especially, all the other are with embodiment 1.The film performance recorded is listed in table 2.

Embodiment 4

Except the metallocene PE consumption changes 6 into especially, all the other are with embodiment 1.The film performance recorded is listed in table 2.

Table 1

HMSPP: high melt strength, propylene, MPE metallocene PE, NA11: nucleator

Table 2 film performance test result

As can be seen from Table 2, compared with prior art, the polypropylene blown film in the present invention, guaranteeing under dystectic prerequisite, its cross direction tear strength is significantly improved, and has obviously reduced the difference of vertical and horizontal tear strengths, has improved mist degree and the light transmission of film.

It should be noted in the discussion above that above-described embodiment, only for explaining the present invention, does not form any limitation of the invention.By the reference exemplary embodiments, invention has been described, but should be understood to word wherein used, is descriptive and explanatory vocabulary, rather than limited vocabulary.Can make modification to the present invention in accordance with regulations in the scope of the claims in the present invention, and within not deviating from scope and spirit of the present invention, the present invention be revised.Although the present invention who wherein describes relates to specific method, material and embodiment, and does not mean that the present invention is limited to wherein disclosed particular case, on the contrary, the present invention can extend to other all material, methods and applications with identical function.

Claims (12)

1. the polypropene composition for the preparation of blown film, comprise that the melt strength of 100 parts is greater than 0.2 newton's polypropylene and 0.5 ~ 11 part of metallocene PE.

2. polypropene composition according to claim 1, is characterized in that, the polypropylene that described polypropene composition comprises 100 parts and 0.5 ~ 8 part of metallocene PE preferably comprise polypropylene and 1 ~ 3 part of metallocene PE of 100 parts.

3. polypropene composition according to claim 1 and 2, is characterized in that, described composition comprises nucleator.

4. polypropene composition according to claim 3, is characterized in that, described nucleator is selected from nucleator in organic phosphate class and Dibenzalsorbierite derivatives class nucleator.

5. according to the described polypropene composition of claim 3 or 4, it is characterized in that, comprise the described nucleator of 0.1 ~ 0.8 part in described composition, preferably comprise the described nucleator of 0.4 ~ 0.6 part.

6. a polypropylene blown film, it comprises that the melt strength of 100 parts is greater than 0.2 newton's polypropylene and 0.5 ~ 11 part of metallocene PE.

7. polypropylene blown film according to claim 6, is characterized in that, the polypropylene that comprises 100 parts in described polypropylene blown film and 0.5 ~ 8 part of metallocene PE preferably comprise polypropylene and 1 ~ 3 part of metallocene PE of 100 parts.

8. according to the described polypropylene blown film of claim 6 or 7, it is characterized in that, in described film, comprise nucleator.

9. polypropylene blown film according to claim 8, is characterized in that, described nucleator is selected from nucleator in organic phosphate class and Dibenzalsorbierite derivatives class nucleator.

10. polypropylene blown film according to claim 8 or claim 9, is characterized in that the nucleator that comprises 0.1 ~ 0.8 part in described film preferably comprises the nucleator of 0.4 ~ 0.6 part.

11. according to the described polypropylene blown film of any one in claim 6 ~ 10, it is characterized in that, the tear strength of described film is more than 130N/mm, preferably more than 140N/mm, cross direction tear strength and machine direction tear differ and are less than 24%, preferably are less than 20%, are more preferably less than 15%.

12. according to the described polypropylene blown film of any one in claim 6 ~ 11, it is characterized in that, the mist degree of described film is less than 22%, transmittance is greater than 91%, and fusing point is higher than 166 ℃.