JP2704894B2 - Polyolefin resin composition - Google Patents

Description

The present invention relates to a novel polyolefin-based resin composition. More specifically, the present invention provides a resin composition capable of continuously and stably forming a polyolefin film having excellent blocking resistance, yellowing resistance, and corrosion resistance, and having little decrease in transparency due to heat sterilization. It is about things.

[Prior art] Conventionally, polyolefin films such as polyethylene film and polypropylene film have been used for wrapping and packaging for products such as food packaging, textile packaging, pharmaceutical packaging, miscellaneous goods packaging, agriculture, construction, and home use. Widely used for such applications.

Various additives are usually added to such a polyolefin film for the purpose of imparting preferable properties. For example, as an anti-blocking agent to improve the handleability, synthetic zelite, diatomaceous earth,
Silica and the like are added. In addition, particularly in a polyolefin-based resin produced using a Ziegler-type catalyst,
Since halides caused by the catalyst used are contained, if this polyolefin resin is molded as it is,
Hydrogen halide may be generated during molding to corrode the molding machine, or the film may cause an undesired situation such as yellowing over time. The agent is added. As the residual chlorine scavenger, for example, higher fatty acid metal salts and the like are known, and hydrotalcite compounds are also known to be effective (Japanese Patent Laid-Open No.
-49258).

By the way, when the polyolefin film is used in the field of food packaging and the like, for sterilization purposes, for example, 90 to 90
It is often boiled at a temperature of about 120 ° C. However, although the film to which the anti-blocking agent is added has good blocking resistance, such a film has a drawback that transparency (boil whitening) is reduced by such heat sterilization.

In addition, when a higher fatty acid metal salt is solely added as a residual chlorine scavenger, a problem arises in that boil whitening of the film is easily promoted.On the other hand, when a hydrotalcite-based compound is solely added, sticky substances adhere to a die lip. Occurs, and it is difficult to perform stable continuous molding.

As described above, at present, a resin composition capable of stably and continuously forming a polyolefin film having excellent blocking resistance, yellowing resistance, corrosion resistance, and suppressed boil whitening has not yet been found. is there.

[Problems to be Solved by the Invention] Under such circumstances, the present invention is to stabilize a polyolefin film having excellent blocking resistance, yellowing resistance, and corrosion resistance and in which boil whitening is suppressed. The purpose of the present invention is to provide a resin composition that can be continuously molded by heating.

[Means for Solving the Problems] The present inventors have conducted intensive studies to develop a polyolefin-based resin composition having the above-mentioned preferable properties. As a result, an anti-blocking agent and a hydrotal It has been found that the object can be achieved by combining the site-based compound and the higher fatty acid metal salt and blending them at a predetermined ratio, and based on this finding, the present invention has been completed.

That is, the present invention relates to (A) polyolefin resin 100
(B) 0.01 to 2.0 parts by weight of the antiblocking agent
Parts by weight, (C) hydrotalcite compound 0.01 to 0.2
The present invention provides a polyolefin-based resin composition characterized by containing 0.01 parts by weight and (D) 0.01 to 0.2 parts by weight of a higher fatty acid metal salt.

 Hereinafter, the present invention will be described in detail.

In the composition of the present invention, examples of the polyolefin resin used as the component (A) include linear low-density polyethylene, high-pressure low-density polyethylene, high-density polyethylene, polypropylene, propylene-ethylene copolymer, polybutene-1, Poly-4-methylpentene-1 and the like. These polyolefin resins are:
Species may be used, or two or more may be used in combination.

As the linear low-density polyethylene, ethylene, preferably 0.2 to 20 mol%, more preferably 1 to 10 mol%
At least 1 mole% of α-olefin having 3 to 10 carbon atoms
Seeds and copolymers in the liquid or gas phase can be mentioned. Examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, 4-
Methylpentene-1,4-methylhexene-1,4,4-
Dimethylpentene-1 or the like can be used. Among such linear low-density polyethylenes, the density is particularly high.
0.900 to 0.960 g / cm ³ , preferably 0.910 to 0.940 g / cm ³ , and a melt index (MI) of 0.1 to 10 g / 1
Those within the range of 0 minutes, preferably 0.5 to 5.0 g / 10 minutes are suitable.

In the composition of the present invention, there is no particular limitation on the antiblocking agent used as the component (B), and any one can be selected from those conventionally used in polyolefin films. Examples of such an anti-blocking agent include zeolite,
Examples include amorphous aluminosilicate obtained by treating zeolite with acid, synthetic silica, diatomaceous earth, talc, feldspar and the like.

These anti-blocking agents may be used alone or in combination of two or more,
The compounding amount is 100 parts of the polyolefin resin (A).
0.01 to 2.0 parts by weight, preferably 0.01 to 2.0 parts by weight,
It is selected in the range of 1.5 parts by weight. If the amount is less than 0.01 part by weight, the blocking resistance may be insufficient. If the amount exceeds 2.0 parts by weight, problems such as boiling whitening property and molding stability may occur. In the composition of the present invention,
The hydrotalcite-based compound used as the component (C) is a hydrated basic carbonate of magnesium or aluminum, and may be either a natural product or a synthetic product.
Natural products have a chemical structure represented by Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, while synthetic products having different ratios of Mg and Al, for example, a chemical formula of Mg ₄ Al _{2 (OH) 12 CO 3 ·} 3H 2 O, Mg 5 Al 2 (OH) 14 CO 3 · 4H 2 O, Mg 10 Al 2 (OH) 22 (CO 3) 2 · 4H 2 O, Mg 4.5 Al 2 ( OH) ₁₃ CO ₃ · 3.5H ₂ O, and the like.

These hydrotalcite-based compounds may be used alone or in combination of two or more. The compounding amount is 0.01 to 0.2 with respect to 100 parts by weight of the polyolefin resin (A). Parts by weight, preferably in the range of 0.02 to 0.15 parts by weight. When the amount is less than 0.01 part by weight, the boiling whitening resistance and corrosion resistance are insufficient, and when the amount exceeds 0.2 part by weight, there is a problem in molding stability.

In the composition of the present invention, examples of the higher fatty acid metal salt (metal soap) used as the component (D) include calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, calcium palmitate and the like.

These higher fatty acid metal salts may be used alone or in combination of two or more, and the amount thereof is 0.01 to 0.2 parts by weight per 100 parts by weight of the polyolefin resin (A). Parts by weight, preferably in the range of 0.02 to 0.15 parts by weight. If the amount is less than 0.01 part by weight, stable continuous molding becomes difficult. If the amount exceeds 0.2 part by weight, the boiling whitening resistance becomes insufficient, and the object of the present invention is not achieved.

In the polyolefin-based resin composition of the present invention, various additives usually used in polyolefin-based resins, for example, antioxidants, light stabilizers, lubricants, antistatic agents, antifogging agents, nucleating agents, coloring agents, A clarifying agent, a metal deactivator, a radical generator and the like can be added as desired within a range not to impair the object of the present invention.

Preferable examples of the antioxidant include phenol-based and phosphorus-based ones, and the combination of these is particularly preferred. Examples of the phenolic antioxidant include 2,6-di-t-butyl-4-methylphenol, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate (manufactured by Ciba Geigy, Irgano × 31
14), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), n-octadecyl-3- (3 ', 5'
-Di-t-butyl-4'hydroxyphenyl) propionate (Irgano x 1076, manufactured by Ciba-Geigy), 4,4'-
Thiobis (3-methyl-6-t-butylphenol),
Tetrakis [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane (manufactured by Ciba Geigy, Irgano × 1010), 4,4'-butylidenebis (3-methyl-6) -T-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), N, N'-hexamethylenebis (3,5-
Di-tert-butyl-4-hydroxyhydrocinnamide)
(Ciba Geigy, Irgano × 1098), triethylene glycol-bis [3- (3′-t-butyl-5′-methyl-4-hydroxyphenyl) propionate], bis (3,5-di-t-butyl) A mixture of (ethyl 4-hydroxybenzylphosphonate) calcium and a PE wax (weight ratio 1: 1) (trade name, manufactured by Ciba Geigy) can be used. Examples of the phosphorus antioxidants include distearyl pentaerythritol diphosphite, tetrakis (2,
4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite (Sandostab P-EPQ, manufactured by Sando Co., Ltd.), trisnonylphenylphosphite, tris (2,4-di-
(t-butylphenyl) phosphite and the like.
Examples of the light stabilizer include, for example, salicylate, benzophenone, triazole, anilide oxalate hindered amine, and the like.
For example, stearic acid amide, palmitic acid amide, oleic acid amide, erucic acid amide and the like can be mentioned.

The polyolefin-based resin composition of the present invention comprises the above (A)
It can be prepared by melt-kneading the component, the component (B), the component (C), the component (D) and various additives used as desired according to a conventional method. This melt kneading, for example, Henschel mixer, single or twin screw extruder,
It can be performed using a Banbury mixer, a roll, or the like.

The polyolefin-based resin composition of the present invention thus prepared is a method conventionally used for producing a polyolefin-based film, such as a casting method.
The film can be formed by a calendering method or an extrusion method such as a T-die method or an inflation method.

The film obtained from the polyolefin resin composition of the present invention has excellent blocking resistance, yellowing resistance, and corrosion resistance, and also has good boiling whitening resistance, and is suitable for various uses including food packaging. Used for

[Examples] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

 In addition, each characteristic was evaluated according to the following method.

(1) Boil whitening resistance A film with a film thickness of 50 μm was created by cast molding.
It was subjected to a boil whitening test.

This cast film is heat-treated in hot water (ion-exchanged water) at 105 ° C for 30 minutes, cooled and dried with ion-exchanged water at 15 ° C, and the haze value of the film before and after the heat treatment is measured. The change (Δ haze) was used as an index of boiling whitening. The larger the Δhaze, the more easily the boil whitening occurs. When the Δhaze is 1.0 or more, there is a problem.

(2) Molding stability Using a hollow molding machine, extrude a barison for 1 hour under molding conditions of a resin temperature of 250 ° C and a discharge rate of 5 kg / hr, and then measure the length of the sticky substance (eye cast) adhering to the die lip. Then, the molding stability was evaluated. The longer the length is, the more easily the eye tarnish is generated. If the length of the adhesive is 1.0 mm or more, there is a problem.

(3) Blocking resistance When two cast films of 5 cm length and 25 cm width are stacked, a load of 9 kg is placed, left at 60 ° C. for 3 hours, and peeled vertically at a pulling speed of 200 mm / min. The maximum value (blocking strength: g / 100 cm ² ) was measured and evaluated. The higher the blocking strength, the poorer the blocking resistance, and the problem is that the blocking strength is 60 g / 100 cm ² or more.

(4) Corrosion resistance A test piece (metal piece) was prepared by pressing the resin composition on a metal piece made of S10C carbon steel at 250 ° C. and 5 kg / cm ² for 30 minutes. After humidifying the metal pieces for 5 days, the hue (a * value) of the metal pieces was determined with a color computer manufactured by Suga Test Instruments Co., Ltd. and evaluated. The greater the a * value, the greater the corrosiveness.
This is a problem.

 The following were used as components of the resin composition.

・ Polyolefin resin (1) LL-I: Linear low density polyethylene MI = 2.0 g / 10 min Density = 0.915 g / cm ³ α-olefin = octene-1 (2) LL-II: Linear low density Polyethylene MI = 2.0 g / 10 min Density = 0.930 g / cm ³ α-olefin = octene-1 (3) LL-III: Linear low density polyethylene MI = 4.0 g / 10 min Density = 0.915 g / cm ³ α -Olefin = octene-1 (4) LL-IV: Linear low density polyethylene MI = 2.0 g / 10 min Density = 0.915 g / cm ³ α-olefin = butene-1 (5) PP-I: Polypropylene MI = 7.0g / 10min ・ Anti-blocking agent (1) Shilton AMT (manufactured by Mizusawa Chemical Co., Ltd.) Amorphous aluminosilicate (acid-treated and calcined product of Na-4A type zeolite), average particle size 2.5μm, refractive index 1.495.

(2) Super fine super floss (SF-SF; manufactured by Johns-Manville) diatomaceous earth, average particle size 3.5 μm.

(3) Syloid 244 (manufactured by Fuji Devison Chemical Co., Ltd.) synthetic silica, average particle size
1.8 μm.

・ Hydrotalcite-based compound DHT-4A (Kyowa Chemical Industry Co., Ltd.) Mg _4.5 Al ₂ (OH) ₁₃ CO ₃・ 3.5H ₂ O ・ Higher fatty acid metal salt Karste S (Calcium stearate, manufactured by NOF CORPORATION) Examples 1 to 11, Comparative Examples 1 to 8 Polyolefin-based resin compositions having the composition shown in Table 1 were prepared, and their properties were evaluated. The results are shown in the table.

[Effects of the Invention] According to the present invention, blocking resistance and yellowing resistance are obtained by combining a polyolefin-based resin with an anti-blocking agent, a hydrotalcite-based compound and a metal salt of a higher fatty acid at predetermined ratios. And a resin composition capable of continuously and stably forming a polyolefin film having excellent corrosion resistance and good boiling whitening resistance.

The polyolefin-based film obtained from the composition of the present invention has the above-mentioned excellent characteristics, and thus is suitably used for various uses including food packaging.

Claims (1)

(57) [Claims] 1. An anti-blocking agent (B) in an amount of 0.01 to 2.0 parts by weight per 100 parts by weight of the polyolefin resin (A).
A polyolefin resin composition comprising (C) 0.01 to 0.2 parts by weight of a hydrotalcite compound and (D) 0.01 to 0.2 parts by weight of a higher fatty acid metal salt.