JP3135288B2 - Polypropylene film with high rigidity and excellent impact resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 food and fiber packaging because of their excellent transparency, mechanical strength, heat resistance and dimensional stability.

However, a conventionally known polypropylene film is a polypropylene cast film obtained by melt-extruding a propylene homopolymer, which is characterized by impact resistance, particularly high rigidity, by a T-die method, especially at a low temperature. There is a drawback that the impact strength is remarkably reduced. To solve this drawback, JP-A-61-98756 discloses blending a soft elastomer and a linear low-density polyethylene with a polypropylene polymer.

In Japanese Patent Application Laid-Open 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 are used. ing.

[0005]

However, in these conventional techniques, if an attempt is made to improve the impact resistance by using an elastomer, a linear low-density polyethylene or the like,
In order to further improve the effect, a large amount of addition is indispensable and uneconomical, and the heat blocking property is insufficient. In addition, in the technology based on the addition of a plasticizer and a combination of a plasticizer and a soft elastomer, the rigidity is reduced as the impact property is improved, the smoke emission during molding is deteriorated, and the productivity is increased due to the plasticizer roll adhesion and the like. However, there was a problem in terms of safety and health, and it could not be used especially for food packaging.

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

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that such problems can be solved by adding liquid paraffin to a polypropylene resin, thereby completing the present invention. It has been reached.

That is, the present invention relates to a propylene homopolymer and / or a propylene-ethylene copolymer having an ethylene content of 0 to 2% by weight.
Add 0.2-5.0 parts by weight of liquid paraffin to 00 parts by weight
Further, it is a polypropylene film formed by using a resin composition containing no inorganic filler and having high rigidity and excellent impact resistance.

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

[0010] The method for producing these polypropylene resins is not particularly limited, and 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 a method in which substantially no liquid medium exists. It is manufactured by a gas phase polymerization method or the like.

As the catalyst, various known catalysts can be used, for example, a catalyst comprising an active titanium trichloride catalyst and an organic aluminum, or an active titanium obtained by supporting titanium tetrachloride or titanium trichloride on magnesium halide. Examples of the catalyst include a catalyst and an organoaluminum. The obtained polypropylene resin has a molecular weight of less than a melt flow value (ASTM D-1238 230 ° C 2.16 Kg load or less, M
Abbreviated as I. If it is about 5 to 15 g / 10 min, a commercially available and easily available one can be used.

If the MI is less than 5 g / 10 min, the high-speed film-forming property becomes poor particularly in film forming by the T-die method, and if it exceeds 15 g / 10 min, the tube becomes unstable particularly in the film forming by the inflation method. This is not preferable because it causes problems such as uneven thickness.

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

The liquid paraffin used in the present invention is commercially available and is not particularly limited, but has a viscosity (JIS K-2283)
Of 210 to 380 SUS second are preferably used. Specific examples are Moresco White P-260 (manufactured by Matsumura Oil)
Plastic Oil 250 (manufactured by Witco) and the like.

The amount of the liquid paraffin to be added is in the range of 0.2 to 5 parts by weight based on 100 parts by weight of the polypropylene resin. The improvement effect is low,
Even if it is added in excess of 5 parts by weight, the impact resistance of the polypropylene film obtained does not improve so as to be proportional to the amount added, but rather decreases the rigidity and further deteriorates the smoke generating property at the time of molding. Not preferred.

In addition to the above components, antioxidants, heat stabilizers, antistatic agents, etc., which do not significantly impair the effects of the present invention,
Lubricants and anti-blocking agents may be added. Further, addition of a thermoplastic elastomer, a linear low-density polyethylene, or the like, as necessary, does not hinder the addition.

The polypropylene film of the present invention is prepared by adding a polypropylene resin, liquid paraffin, and various additives as needed within a range not to impair the object of the present invention, and mixing the resulting mixture using a known mixer such as a Hensiel mixer. Then, the polypropylene resin obtained by melt extrusion is melt-extruded at a melting temperature of 190 to 250 ° C. by, for example, an inflation method or a T-die method, and rapidly cooled to obtain a polypropylene film.

The film thus obtained is rigid,
Because of its good impact resistance, it can be used for various applications including food and fiber packaging.

[0019]

The present invention will be described below in detail with reference to examples. In the following description: ・ MI: g / 10min ASTM D-1238 ・ Haze:% ASTM D-1003 ・ Impact strength: kg ・ cm / mm ASTM D-3420 compliant ・ Rigidity; Young's modulus: kg / mm ² ASTM Conforms to D-882; Yield point stress: kg / mm ² Conforms to ASTM D-882.-Smoke generation: Evaluate the smoke generated from the vicinity of the die during molding by visual inspection. (1. No smoke. 2. Some smoke is observed. 3. Many smokes.)

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 Sekiyu KK) ), 0.04 parts by weight of a phosphorus-based antioxidant (Sandstarb PEP-Q, manufactured by Sando) and 0.10 parts by weight of a phenolic antioxidant (Irganox 1010, manufactured by Ciba-Geigy), a neutralizing agent ( Magnesium hydroxide Kisuma 5A, Kyowa Chemical Co., Ltd. 0.03 parts by weight, slip agent (erucamide amide Neutron S, Nippon Seika Co., Ltd.) 0.08 parts by weight, anti-blocking agent (silica)
(Syloid 244, Fuji Devison Co., Ltd.) 0.15 parts by weight were mixed with a Hensiel mixer, and the resulting pellets were melt-extruded with an extruder.
Using a film obtained by molding a μ film, physical properties were measured by the above evaluation methods.

In comparison with the comparative example in which the amount of the liquid paraffin added deviated from the proper amount, the examples exhibited improved low-temperature impact resistance, and
There was little decrease in rigidity, and at the same time, smoke emission during molding was good. Table 1 shows the results.

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

COMPARATIVE EXAMPLES 5-6 A polypropylene resin was used as a propylene-ethylene copolymer (ethylene content 2.5%, MI 6.0 g / 10 min or less, PP-3
Abbreviated. ) Was evaluated in the same manner as in Example 6 except that the film properties were changed. Table 1 shows the results.

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.), and a neutralizing agent (calcium stearate, Sakai Chemical) 0.1 parts by weight, 0.25 parts by weight of a slip agent (oleic acid amide neutron, manufactured by Nippon Seika) and 0.3 parts by weight of an anti-blocking agent (silica thyroid 244, manufactured by Fuji Devison) using a Hensiel mixer After that, pellets obtained by melt extrusion by an extruder were formed into a film having a thickness of 30 μm by a water-cooled inflation film forming machine, and the physical properties of the film were evaluated by the above evaluation method using the obtained film. The results are shown in Table 1.

[0025]

[Table 1]

[0026]

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

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Claims (1)

(57) [Claims] 1. A propylene homopolymer and / or propylene-ethylene copolymer having an ethylene content of 0 to
Inorganic fillers added by adding 0.2-5.0 parts by weight of liquid paraffin to 100 parts by weight of 2% by weight of polypropylene resin
Using Manai resin composition excellent polypropylene film impact resistance high rigidity molded.