JPH0525334A - High-rigidity polypropylene film with excellent impact resistance - Google Patents

Abstract

PURPOSE:To obtain the subject film useful for food or textile packaging use, especially excellent in impact resistance at low temperatures by adding liquid paraffin to a specific polypropylene resin. CONSTITUTION:The objective film can be obtained by melt extrusion at 190-250'C followed by quenching of a composition prepared by incorporating (A) 100 pts.wt. of propylene homopolymer and/or a polypropylene resin having 0-2wt.% ethylene content consisting of an ethylene-propylene copolymer with (B) 0.2-5.0 pts.wt. of liquid paraffin with a viscosity of pref. 210-380SUSsec and (C) other ingredient (s) such as antioxidant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene film having high rigidity and excellent impact resistance.

[0002]

2. Description of the Related Art Polypropylene films are widely used for foods, fiber packaging and the like because of their excellent transparency, mechanical strength, heat resistance and dimensional stability.

However, conventionally known polypropylene films are polypropylene cast films obtained by melt-extruding a propylene homopolymer characterized by high impact resistance, particularly high rigidity by the T-die method, especially at low temperature. There is a drawback that the impact property is remarkably lowered. In order to solve this drawback, in JP-A-61-98756, a polypropylene polymer is blended with a soft elastomer, a linear low density polyethylene and the like.

Alternatively, in JP-A No. 2-80445, means such as addition of a plasticizer (octyl epoxy stearate, diisononyl adipate, butyl stearate, etc.) and addition of a plasticizer in combination with a soft elastomer is used. ing.

[0005]

However, in these conventional techniques, when an attempt is made to improve impact resistance by using an elastomer, a linear low-density polyethylene or the like,
Addition of a large amount is indispensable for further improving the effect, which is uneconomical and lacks heat blocking resistance. In addition, in the technology that uses plasticizers and the combination of plasticizers and soft elastomers, the rigidity decreases as the impact resistance improves, and the smoke generation during molding process deteriorates and the productivity of plasticizers due to roll adhesion increases. However, it could not be used for food packaging in particular.

[0006] Therefore, it is economical because there is no reduction in work due to smoke emission during molding, it is preferable from the viewpoint of safety and hygiene, and
A polypropylene film having excellent impact resistance without impairing the reduction in rigidity has been desired.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the addition of liquid paraffin to polypropylene resin solves the above problems, and complete the present invention. It came to.

That is, the present invention relates to a propylene homopolymer and / or a propylene-ethylene copolymer having a polypropylene content of 0 to 2% by weight.
A polypropylene film molded with a resin composition obtained by adding 0.2 to 5.0 parts by weight of liquid paraffin to 00 parts by weight and having high rigidity and excellent impact resistance.

The polypropylene resin in the present invention means
It is a propylene homopolymer, a random or block copolymer of propylene and ethylene, and a mixture thereof.

The method for producing these polypropylene resins is not particularly limited, and includes a solvent polymerization method using an inert liquid medium as a polymerization medium, a bulk polymerization method using propylene itself as a liquid medium, or the presence of a substantially liquid medium. Not manufactured by a gas phase polymerization method.

As the catalyst, various known catalysts can be used, for example, a catalyst comprising an active titanium trichloride catalyst and organic aluminum, or an active titanium obtained by supporting titanium tetrachloride or titanium trichloride on magnesium halide. A catalyst composed of a catalyst and organoaluminum may be mentioned, but the molecular weight of the resulting polypropylene resin is a melt flow value (ASTM D-1238 230 ℃ 2.16 Kg load or less, M
Abbreviated as I. If it is about 5 to 15 g / 10 min in (), a commercially available product which is usually commercially available can be used.

If this MI is less than 5 g / 10 min, the high-speed film forming property becomes poor especially in the film forming by the T-die method, and if it exceeds 15 g / 10 min, the tube becomes unstable especially in the film forming by the inflation method. Therefore, there is a problem such as uneven thickness, which is not preferable.

When a copolymer of propylene and ethylene is used as the polypropylene resin, the ethylene content is preferably 2% by weight or less. When the ethylene content exceeds 2% by weight, the impact resistance at low temperature is improved, but the rigidity is remarkably lowered, which is not preferable. The ethylene content, which has both impact resistance and rigidity, is preferably 2% by weight or less, and more preferably 1.5% by weight or less.

The liquid paraffin used in the present invention is a commercially available product and is not particularly limited, but the viscosity (JIS K-2283)
Of 210 to 380 SUS seconds are preferably used, and specific examples include Moresco White P-260 (Matsumura Oil Co., Ltd.),
Plastic oil 250 (manufactured by Witco) and the like can be mentioned.

The addition amount of these liquid paraffins is in the range of 0.2 to 5 parts by weight with respect to 100 parts by weight of the polypropylene resin. If the addition amount is less than 0.2 parts by weight, the impact resistance of the obtained polypropylene film is The improvement effect is low,
Even if added in an amount of more than 5 parts by weight, the impact resistance of the polypropylene film obtained does not improve to the extent that it is proportional to the amount added, rather the rigidity decreases and the smoke emission during molding deteriorates. Not preferable.

In addition to the above components, an antioxidant, a heat stabilizer, an antistatic agent, which does not significantly impair the effects of the present invention,
Lubricants and anti-blocking agents may be added. Further, addition of thermoplastic elastomer, linear low-density polyethylene, etc., if necessary, is not hindered.

In the polypropylene film of the present invention, polypropylene resin, liquid paraffin and various additives as required are added within a range that does not impair the object of the present invention, and they are mixed using a known mixer such as a Henschel mixer. Then, the polypropylene resin obtained by melt-extrusion is melt-extruded at a melting temperature of 190 to 250 ° C. by an inflation method or a T-die method and then rapidly cooled to obtain a polypropylene film.

The film thus obtained has rigidity,
Because of its good impact resistance, it can be used for various purposes such as food and fiber packaging.

[0019]

The present invention will be described in detail below with reference to examples. In the following description, ・ MI: g / 10min ASTM D-1238 ・ Haze:% ASTM D-1003 ・ Impact strength: kg ・ cm / mm According to ASTM D-3420 ・ Stiffness; Young's modulus: kg / mm ² ASTM D-882 compliant; Yield point stress: kg / mm ² ASTM D-882 compliant ・ Smoke emission: Smoke generated near the die during molding is visually evaluated. (1. No smoke. 2. Slight smoke is observed. 3. A lot of smoke is generated.)

Examples 1-5, Comparative Examples 1-3 Propylene homopolymer (MI 9.0 g / 10 min or less, abbreviated as PP-1) 100 parts by weight of liquid paraffin (Moresco White P-260, Matsumura Oil Co., Ltd.) Made), 0.04 part by weight of a phosphorus-based antioxidant (Sandstarve PEP-Q, manufactured by Sand Co.) and 0.10 part by weight of a phenol-based antioxidant (Irganox 1010, manufactured by Ciba Geigy), a neutralizer ( Magnesium hydroxide Kisuma 5A, made by Kyowa Chemical Co., Ltd. 0.03 parts by weight, slip agent (Erukaamide Neutron S, made by Nippon Seika) 0.08 parts by weight, anti-blocking agent (silica)
(Syloid 244, Fuji Davison) 0.15 parts by weight are mixed with a Henschel mixer, and the pellets obtained by melt-extruding with an extruder and then with a T-die film forming machine to a thickness of 30
Physical properties were measured by the above-mentioned evaluation methods using a film obtained by molding a film of μ.

Compared with the comparative example which deviated from the proper addition amount of liquid paraffin, the example has improved low temperature impact resistance, and
There was little decrease in rigidity, and at the same time, smoke generation during molding was good. The results are shown in Table 1.

Examples 6 to 8, Comparative Example 4 Propylene-ethylene copolymer was used instead of propylene homopolymer (MI 7.0 g / 10 min or less at ethylene content 1.0%, P
Abbreviated as P-2. ) Was used and the physical properties of the film obtained in the same manner as in Example 1 were evaluated. It can be seen that the impact resistance is improved as compared with the case of using the propylene homopolymer.
The results are shown in Table 1.

Comparative Examples 5 to 6 A polypropylene resin was used as a propylene-ethylene copolymer (ethylene content 2.5%, MI 6.0 g / 10 min or less, PP-3
Is abbreviated. The physical properties of the obtained film were evaluated in the same manner as in Example 6 except that The results are shown in Table 1.

Examples 9-11, Comparative Example 7 Liquid paraffin was added to 100 parts by weight of PP-1, 0.15 parts by weight of an antioxidant (BHT, manufactured by Takeda Pharmaceutical Co., Ltd.), a neutralizing agent (calcium stearate, Sakai Chemical Co., Ltd.). 0.1 parts by weight, slip agent (oleic acid amide Neutron, manufactured by Nippon Seika Co., Ltd.) 0.25 parts by weight, and anti-blocking agent (silica siloid 244, manufactured by Fuji Devison Co., Ltd.) 0.3 parts by weight are mixed with a Henschel mixer. After that, the pellets obtained by melt extrusion with an extruder were molded into a film having a thickness of 30 μ by a water-cooled inflation method film forming machine, and the physical properties of the film were evaluated by the above-mentioned evaluation methods using the obtained film. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

EFFECT OF THE INVENTION The polypropylene film of the present invention has a good balance of rigidity and impact resistance, is excellent in impact resistance especially at low temperature, and can be used as a food packaging film because it is economically preferable. A wide range of applications can be expected for single layer or composite films, which is industrially superior.

Claims (1)

Claims: 1. A propylene homopolymer and / or a propylene-ethylene copolymer having an ethylene content of 0 to
A polypropylene film with high rigidity and excellent impact resistance formed by using a resin composition obtained by adding 0.2 to 5.0 parts by weight of liquid paraffin to 100 parts by weight of 2% by weight polypropylene resin.