JPH06179787A - Polyvinyl chloride resin composition for food packaging - Google Patents

Abstract

PURPOSE:To provide a polyvinyl chloride resin composition for food-packaging use, having excellent fluidity and thermal stability in extrusion molding and giving a film sufficiently satisfying the cuttability with a saw blade, adhesivity to a vessel, heat-resistance, etc. CONSTITUTION:The objective polyvinyl chloride resin composition for food- packaging use is composed of 100 pts.wt. of a polyvinyl chloride resin having an average polymerization degree of 1,250-1,350, 20-30 pts.wt. of a plasticizer, 0.5-3.0 pts.wt. of a Ca-Zn stabilizer, 0.03-1.0 pt.wt. of synthetic hydrotalcite and 0.1-1.0 pt.wt. of a mixed ester derived from a 2-20C polyhydric alcohol, a 11-20C higher fatty acid and a 4-6C saturated dibasic acid.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyvinyl chloride resin composition for food packaging, and more particularly to a polyvinyl chloride resin composition suitable for forming a wrap film for food.

[0002]

2. Description of the Related Art Wrap films for foods containing polyvinyl chloride as a main component are used for 1) so-called commercial stretch films used for food packaging in supermarkets and various food production areas.
2) It is roughly classified into household wrap films used in ordinary households or restaurants.

The required characteristics of the wrap film of 1) include the ease of stretching the film, the transparency, the surface glossiness, the adhesion between the film and the packaging container or between the films, and the suitability for packaging in an automatic packaging machine.

The wrap film of 2) is usually 10 to 500 m.
It is used by cutting a paper tube wound at the length of the paper tube into a paper box and cutting it to the desired size with a saw blade provided on the edge, so its characteristic is that it is easy to cut with a saw blade. To be done. Further, the adhesion of the film to the packaging container is required to prevent leakage and spilling of the contents, but if the films easily stick to each other, wrinkles are likely to occur and workability is impaired. It is required to be harder and less sticky than a film. To meet these requirements, it has been conventionally known that it is effective to reduce the amount of a plasticizer blended in a polyvinyl chloride resin composition or to use a polyvinyl chloride having a high degree of polymerization. .

However, the method of reducing the amount of the plasticizer or using a resin having a high degree of polymerization lowers the fluidity of the resin at the time of molding and thus deteriorates the molding processability remarkably. Therefore, conventionally, as a measure against the above, by reducing the amount of plasticizer and using polyvinyl chloride having a relatively low degree of polymerization of 600 to 1,000, a method of preventing the deterioration of fluidity due to the decrease of the plasticizer is used. Has been taken.

However, when using the wrap film, it is usual to heat the food in a microwave oven after packaging the food, and it is required that the film has heat resistance and adhesion to the container. To this end, it is desirable to increase the degree of polymerization of polyvinyl chloride, and it is considered that the average degree of polymerization is around 1,300, especially considering the processability.

Since the low-polymerization product lowers the heat resistance of the film, it has been a serious problem in applications requiring heating by a microwave oven. The low-polymerization product also affects the thermal stability of the film and causes a problem that it is easily decomposed during molding. For this, a method of increasing the amount of the stabilizer can be considered, but it cannot be said to be effective because it also increases the cost.

[0008]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to improve the fluidity and heat stability during extrusion processing, and to obtain the obtained film, which is required as a wrap film for foods in general households. It is intended to provide a polyvinyl chloride resin composition for food packaging, which sufficiently satisfies various characteristics such as ease of cutting with a blade, adhesion to a container, and heat resistance.

[0009]

The polyvinyl chloride resin composition for food packaging according to the present invention has an average degree of polymerization of 1,250 to
100 parts by weight of 1,350 polyvinyl chloride resin, plasticizer 20-30
Parts by weight, Ca-Zn stabilizer 0.5 to 3.0 parts by weight, synthetic hydrotalcite 0.03 to 1.0 parts by weight and carbon atom number 2
~ 20 Polyhydric alcohols, C 11 -C 20 higher fatty acids, and C 4 -C 6 saturated dibasic acid mixed esters
0.1 to 1.0 part by weight.

Explaining this in more detail, the polyvinyl chloride resin blended as the main component in the polyvinyl chloride resin composition for food packaging of the present invention has an average degree of polymerization of
It ranges from 1,250 to 1,350. If it exceeds 1,350, the processability is poor unless a large amount of plasticizer is added. Therefore, if a large amount of plasticizer is added, bleeding of the plasticizer increases and the heat resistance of the film decreases. On the other hand, 1,250
If less than, the heat resistance of the formed film in the microwave oven is reduced and it becomes difficult to cook at a desired temperature, and the film becomes soft, the cut property is reduced, and the adhesiveness between the films is increased. Workability is reduced.

As the polyvinyl chloride resin, in addition to vinyl chloride homopolymer, a copolymer of vinyl chloride containing 50% by weight or more of vinyl chloride and a vinyl-based monomer copolymerizable therewith, vinyl chloride and various vinyl chloride resins can be used. Polymers or graft polymers of polyvinyl chloride and vinyl-based monomers, post-chlorinated vinyl chloride polymers and mixtures thereof are included, which include bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization and the like. Also included are those produced by the method of.

Vinyl-based monomers used in this copolymerization or graft polymerization include olefins such as ethylene and propylene; halogenated olefins other than vinyl chloride such as vinylidene chloride and vinyl fluoride; vinyl acetate,
Vinyl esters such as vinyl laurate; alkyl vinyl ethers such as 2-ethylhexyl vinyl ether and dodecyl vinyl ether; acrylic acid or its esters such as acrylic acid, methyl acrylate, ethyl acrylate; methacrylic acid, methyl methacrylate, Methacrylic acid or its esters such as 2-ethylhexyl methacrylate; Maleic acid or its esters; Acrylic derivatives such as maleic anhydride, acrylonitrile, styrene; Nt-butylmaleimide, N-cyclohexylmaleimide, etc. -Substituted maleimides may be mentioned, and these may be used alone or in combination of two or more.

The polymers which can be graft-polymerized with vinyl chloride include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, polybutadiene-styrene-methyl methacrylate, polybutadiene-acrylonitrile- (Α-
Methyl) styrene, polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, crosslinked acrylic rubber and the like are exemplified.

The plasticizer compounded as the second component in the polyvinyl chloride resin composition is the vinyl chloride resin described above.
It is used in a proportion of 20 to 30 parts by weight, preferably 25 to 30 parts by weight, based on 100 parts by weight. If the amount is less than 20 parts by weight, the resin is inferior in processability such as fluidity and heat stability, so that continuous molding for a long time is difficult and the adhesion of the molded film to a container becomes insufficient. Further, if it exceeds 30 parts by weight, the processability such as fluidity and thermal stability tends to improve, but
The formed film becomes soft and causes a decrease in cuttability, and the heat resistance of the microwave oven is large, especially the heat expansion of the film is large when heated, and the heat resistance is lowered.

As this plasticizer, adipic acid di-i-
Butyl, di-n-butyl adipate, di-i adipate
-Nonyl, dioctyl adipate, di-n- sebacate
Aliphatic dibasic acid esters such as butyl; hydroxy polyvalent carboxylic acid esters such as tributyl acetylcitrate, triethyl acetylcitrate, tri-2-ethylhexyl acetylcitrate; methyl acetylliminate, methyl palmitate, stearin Fatty acid esters such as methyl acid stearate-n-butyl stearate and butyl oleate; di-n-butyl phthalate, dihexyl phthalate, dioctyl phthalate, butylbenzyl phthalate, -n-octyl-n-decyl phthalate. Such as phthalic acid esters; pentaerythritol ester, glycol esters such as diethylene glycol benzoate; phosphoric acid esters such as tricresyl phosphate, triphenyl phosphate; epoxidized soybean oil, epoxidized linseed oil, etc. Xylated oils such as trialkyl trimellitate, tetra-n-octyl pyromellitate, polypropylene adipate, and other polyester plasticizers, which are used alone or in combination of two or more, Judging from the fluidity of the composition when selecting or combining, the melt viscosity at 200 ° C is 1
× 10 ³ to 1 × 10 ⁵ poise, preferably 1 × 10 ³ to 1 × 10
^It is good to have ⁴ poise.

The Ca-Zn stabilizer added as the third component to the polyvinyl chloride resin composition is 0.5 to 3.0 parts by weight, preferably 100 parts by weight of the vinyl chloride resin.
It is used in a proportion of 0.8 to 1.5 parts by weight, but if it is less than 0.5 parts by weight, the effect of improving the thermal stability is not sufficient and 3.0
If the amount is more than parts by weight, bleeding of the stabilizer component, whitening of the film due to bloom, and excessive slidability of the stabilizer component may cause gelation delay during kneading, resulting in poor processability.

Examples of the Ca-Zn stabilizer include 2-ethylhexylic acid, benzoic acid, isodecanoic acid, citric acid,
Calcium salts of higher fatty acids such as sorbic acid and 2
Examples include zinc salts of higher fatty acids such as ethylhexylic acid, isodecanoic acid and neodecanoic acid, and these are used alone or in combination of two or more.

The stabilizer also serves as an antioxidant, and tris (nonylphenyl) phosphite,
2-2'-methylenebis (4-methyl-6-t-bitylphenol), synthetic isoparaffin petroleum hydrocarbon, tridecyl alcohol, 1-3-butanediol, dipropylene glycol, dehydroacetic acid and the like may be used in combination as appropriate. it can. The amount of each of these used is 100% vinyl chloride resin.
It is preferably 1 part by weight or less with respect to parts by weight.

The synthetic hydrotalcite compounded as the fourth component has the formula: Mg _1-x Al _x (OH) _{2 An} ^- _{x /} n.mH
₂ O (provided that 0 <x <0.5, 0 <m <1, and A ⁿ⁻ represents an n-valent anion), and among these, A ⁿ⁻ is CO ₃ ²⁻ and HPO. ₄ ²⁻ , SO ₄ ²⁻ , OH ⁻
And the like are preferable.

This addition amount is 0.03 to 1.0 part by weight, preferably 0.1 to 0.5 part by weight, relative to 100 parts by weight of the above vinyl chloride resin. If it is less than 0.03 part by weight, the effect of improving thermal stability is obtained. If the amount is not sufficient and the amount exceeds 1.0 part by weight, the thermal stability is improved, but so-called gelation time is prolonged, and the kneading at the time of extrusion molding becomes incomplete, resulting in deterioration of processability. In addition, the rise in the processing temperature due to this brings disadvantages such as an increase in the amount of energy and a burn caused by excessive heating.

A mixed ester of a polyhydric alcohol having 2 to 20 carbon atoms, a higher fatty acid having 11 to 20 carbon atoms and a saturated dibasic acid having 4 to 6 carbon atoms as a fifth component is used as a so-called lubricant. The amount thereof is 0.1 to 1.0 part by weight, preferably 0.4 to 0.7 part by weight, based on 100 parts by weight of the vinyl chloride resin. If it is less than 0.1 part by weight, the effect as a lubricant is not sufficient, and if it exceeds 1.0 part by weight, the transparency of the film is lowered and bleeding and blooming are easily caused.

The component ratio of the higher fatty acid and the saturated dibasic acid in this mixed ester is 1 to 4 mol of the saturated dibasic acid to 6 to 12 mol of the higher fatty acid, and particularly 6 to 8 of the higher fatty acid.
A saturated dibasic acid of 1 to 2 moles is preferable because of its stable lubricity.

Examples of the polyhydric alcohol having 2 to 20 carbon atoms used in the above mixed ester include sorbitan, sorbitol, glycerin, polyglycerin, pentaerythritol, dipentaerythritol, propylene glycol, diethylene glycol, and the like. 1 type alone is selected and used.

As the higher fatty acid having 11 to 20 carbon atoms,
Lauric acid, myristic acid, undecanoic acid, tridecanoic acid, pentadecanoic acid, palmitic acid, stearic acid, margaric acid, isostearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, ricinoleic acid, linoleic acid, n-heneiicoic acid, Examples thereof include behenic acid, n-tricoic acid, and arachidonic acid, and these are used alone or in combination of two or more.

Examples of the saturated dibasic acid having 4 to 6 carbon atoms include adipic acid, succinic acid, glutamic acid, etc. These are used alone or in combination of two or more.

Among the mixed esters composed of the above-mentioned respective components, the mixed ester composed of pentaerythritol, stearic acid and stearic acid and the mixed ester composed of pentaerythritol, oleic acid and adipic acid have a lubricating effect. Good from the point.

When a higher fatty acid is used alone as the lubricant, the higher fatty acid reacts with the synthetic hydrotalcite when the resin is heated during extrusion molding, and when stearic acid is used as the higher fatty acid, for example. Magnesium stearate and magnesium isostearic acid are produced when isostearic acid is used, which reduces the function as a lubricant and a stabilizer, and the extruded film becomes cloudy or the resin is unbalanced at the die mouth. It causes the disadvantage that the workability is remarkably deteriorated and the molding becomes impossible, for example.

The polyvinyl chloride resin composition of the present invention thus obtained further contains polyglycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene fatty acid alcohol ether and polyoxy as antifogging agent and antistatic agent. Ethylene alkyl phenyl ether or the like can be appropriately used.

In addition, a well-known method such as an inflation method or a T-die method can be employed for extrusion molding a wrap film from the polyvinyl chloride resin composition of the present invention.

[0030]

The polyvinyl chloride resin composition of the present invention has a high degree of polymerization of the polyvinyl chloride resin contained as the main component and a relatively small amount of the plasticizer, but is It has excellent flowability and thermal stability and good processability, and the resulting film has sufficient heat resistance, adhesion to containers, and workability (cutability, etc.) required for household wrap film. And a uniform surface and a smooth surface can be obtained.

[0031]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the description of these examples. The ingredients shown in Tables 1 and 2 were blended, kneaded with a Henschel mixer, dried up, and then cooled to obtain a mixture having a thickness of 10 by a conventionally known inflation method.
A wrap film having a size of μm and a width of 300 mm was produced. Regarding the polyvinyl chloride resin composition used and the obtained wrap film, the melt viscosity was measured by the following method, the cuttability was evaluated with a saw blade, the adhesion to each container of pottery, glass and stainless steel, and the heat resistance test. The results are shown in Tables 1 and 2. In the table, Experiment No. 1
12 is the present invention and 13 to 22 are comparative examples.

Melt viscosity: 200 according to the reference test in JIS K-7210 using a flow tester (manufactured by Shimadzu Corporation)
It was measured under conditions of ℃ and load of 50 kgf.

Evaluation of cutting performance with a saw blade: As shown in FIG. 1, a wrap film 2 wound around a paper tube 1 is inserted into a rectangular container 3, and a saw blade 4 is directed downward at the lower end of the side wall of the container 3. , And the container 3 was fixed with the container 3 tilted by 10 ° with respect to the horizontal plane. Rewind the wrap film 2 in the direction of the arrow, hang it up on the saw blade 4 and pull it up vertically, and then pull the tip of Tensiron U
It was attached to TM-III-500 (tensile tester, manufactured by Toyo Baldwin Co., Ltd., trade name, not shown). The load when the tip of the wrap film was pulled at a pulling speed of 500 mm / min and the wrap film was cut was measured, and the following evaluation was performed based on the value. ◎ ... less than 500gf. ○ ・ ・ ・ 500 to 2,000gf. ×: Over 2,000gf.

Evaluation of adhesion to container: After filling each container of pottery, glass, and stainless with water and covering the entire container with a wrap film, tilt the container and observe the state where water inside leaks or spills Then, the following criteria were evaluated. ◎ There is no leakage. ○: There is some leakage, but there is no problem in practical use. ×: There are many leaks and it cannot be used in practice.

Heat resistance test: For each wrap film,
It measured based on the heat resistant temperature measuring method of the wrap film for food packaging of Tokyo.

The details of each component used in the above examples are as follows.・ Polyvinyl chloride resin (manufactured by Shin-Etsu Chemical Co., Ltd.) ・ Plasticizer: di-i-nonyl adipate Di-n-alkyl adipate Epoxidized linseed oil

[0037] · Ca-Zn system (manufactured by Asahi Denka Kogyo) composite stabilizer SC-26 · _{hydrotalcite: Mg 0.67 Al 0.33 (OH)} 2 · (CO 3) 0.17 · 0.3H 2 O ( manufactured by Kyowa Chemical Industry Co.,・ Mixed ester: (1: 1: 6) mixed ester of pentaerythritol, adipic acid and oleic acid (manufactured by Henkel Hakusui Co., Ltd.) ・ Other additives: polyglycerin fatty acid ester (anti-fog agent, manufactured by RIKEN VITAMIN CO. )

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

EFFECTS OF THE INVENTION According to the present invention, the film having excellent fluidity and heat stability during extrusion molding and the obtained film is easy to cut with a saw blade, which is required for a wrap film for foods in general households. Thus, various properties such as adhesion to the container and heat resistance can be sufficiently satisfied.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an outline of a cutting property evaluation test method with a saw blade in Examples.

[Explanation of symbols]

 1 ... Paper tube, 2 ... Wrap film, 3 ... Container, 4 ... Saw blade.

Claims (1)

[Claims] 1. A polyvinyl chloride resin having an average degree of polymerization of 1,250 to 1,350, 100 parts by weight, a plasticizer, 20 to 30 parts by weight, and Ca-Zn.
0.5 to 3.0 parts by weight of system stabilizer, synthetic hydrotalcite 0.
03-1.0 parts by weight and polyhydric alcohol having 2 to 20 carbon atoms, higher fatty acid having 11 to 20 carbon atoms and 4 to 6 carbon atoms
1. A polyvinyl chloride resin composition for food packaging, which comprises 0.1 to 1.0 part by weight of a mixed ester with a saturated dibasic acid.