JP4895093B2 - Polyvinyl chloride resin composition and stretch film - Google Patents

Description

  The present invention relates to a vinyl chloride resin composition and a stretch film using the same, and in particular, by using a vinyl chloride resin copolymerized with an acrylic polymer, the amount of plasticizer used can be reduced. This is a vinyl chloride resin composition that does not suffer from a decrease in flexibility, fluidity of the molten resin, or generation of burnt color, which is a problem at the time of reduction. It is related with the stretch film for food packaging which has very little n-heptane extraction amount (it may only be called "n-heptane extraction amount" hereafter) measured by (1).

Many stretch films excellent in transparency, flexibility, and heat sealability have been developed and widely used as food packaging films for food packaging, particularly for fresh foods such as meat, fresh fish, and fruits and vegetables. Usually, these films are generally formed by using a polyvinyl chloride resin composition in which an adipate plasticizer and an epoxidized vegetable oil are used as a plasticizer on a polyvinyl chloride resin.
Conventionally, these films have been regarded as important for the hygiene of the compounding agent and the transferability to foods. In terms of its hygiene, it has established a non-toxic formulation from the additives described in the US FDA standards (Food and Drug Administration) and Japanese PL standards (self-regulatory standards for vinyl chloride resin packaging containers, etc.) About transferability to foods, etc., an extraction test is conducted as an evaporation residue test method by the Ministry of Health and Welfare Notification No. 20 test.
In this background, there are various conventional ones. However, depending on the type and amount of plasticizer and the film thickness, the amount of n-heptane extracted tends to be close to or exceed the regulation value of 150 ppm in the extraction test. In order to reduce the amount of n-heptane extracted, it is conceivable to reduce the amount of plasticizer. However, simply reducing the amount of plasticizer increases the melt viscosity during the molding process, causing heat degradation due to friction between the resins, causing the film to turn red, or to molding processing equipment such as extruders and molds. In some cases, adhesion of the resin occurred.
As a method for solving these problems, a method using a polyester plasticizer (see Patent Document 1) has been proposed.

  However, the polyester plasticizer has a molecular weight of about 1,000 to 3,000, and is less extracted with n-heptane than the conventionally used adipate ester plasticizer, particularly diisononyl adipate (DINA). However, since the flexibility imparting effect is inferior to DINA, in order to bring the flexibility of the film closer to that of the conventional product, a large amount is added (total amount of plasticizer is 50 to 60 parts by mass), or a low molecular weight plasticizer such as DINA is used. A combination is necessary. In this configuration, the extraction amount is lower than the regulated value of 150 ppm or less, but it is difficult to reduce the addition amount of the plasticizer further in consideration of flexibility and molding processability, and the n-heptane extraction amount is further reduced. In order to reduce it, further technical examination is necessary.

Japanese Patent No. 2773839

  Under such circumstances, the present invention is suitable for food container packaging, and is a vinyl chloride resin that is excellent in flexibility and extrudability even when the amount of plasticizer added is reduced, and that the amount of n-heptane extracted can be reduced. An object of the present invention is to provide a composition and a stretch film using the composition.

As a result of intensive studies to solve the above problems, the present inventor has reduced the amount of plasticizer added by using a vinyl chloride resin copolymerized with an acrylic polymer having a glass transition temperature of room temperature or lower. It was also found that a stretch film can be obtained which maintains flexibility, is excellent in molding processability and has a small amount of n-heptane extraction. The present invention has been completed based on such knowledge.
That is, the gist of the present invention is that
(1) Vinyl chloride comprising 5 to 50% by mass of an acrylic polymer comprising (A) and (B) as a polymer component and (A) an acrylic polymer having a glass transition temperature (Tg) of −100 to 0 ° C. 10 to 90 parts by mass of vinyl chloride copolymer having a degree of polymerization of 600 to 1500, (B) 90 to 10 parts by mass of vinyl chloride resin,
(A) + (B) = 100 parts by mass,
(C) adipic acid ester plasticizer及beauty Po Riesuteru plasticizer 5-30 parts by weight,
(D) 1 to 15 parts by mass of an epoxy plasticizer,
A vinyl chloride resin composition comprising:
(E) 0.1 to 2.0 parts by mass of a Ca—Zn stabilizer,
(F) 0.1 to 5.0 parts by mass of an ester of a polyhydric alcohol and a fatty acid,
(2 ) The vinyl chloride resin composition according to the above (1) or (2 ), wherein the acrylic polymer comprises an alkyl acrylate polymer and / or an alkyl acrylate copolymer.
(3 ) Evaporation formed by using the vinyl chloride resin composition according to (1) or (2) above, having a thickness of 6 to 12 μm and stipulated in Ministry of Health and Welfare Notification No. 20 of 1982 The present invention provides a stretch film characterized in that the n-heptane extract amount measured by the residue test method is 50 ppm or less.

  According to the present invention, it is possible to provide a vinyl chloride resin composition suitable for food container packaging, excellent in extrusion processability and capable of reducing n-heptane extractability, and a stretch film using the same.

  The polymer component of the vinyl chloride resin composition of the present invention comprises (A) and (B), and (A) an acrylic polymer having a glass transition temperature (Tg) of −100 to 0 ° C. is 5 to 50 mass. % Graft copolymer, 10 to 90 parts by mass of vinyl chloride copolymer having a degree of polymerization of vinyl chloride portion of 600 to 1500, (B) 90 to 10 parts by mass of vinyl chloride resin, and (A) and ( The total amount of B) is 100 parts by mass.

The vinyl chloride resin used as the component (A) has a degree of polymerization of 600 to 1500, which is obtained by graft copolymerization of an acrylic polymer having a glass transition temperature (Tg) of −100 to 0 ° C. It is a vinyl chloride copolymer. For polymers with an acrylic polymer glass transition temperature below -100 ° C, depending on the copolymerization ratio, the higher the copolymerization ratio, the worse the powder properties (powder fluidity), and the blending while heating with a mixer When it does, it melts quickly, and it becomes a dango shape in a mixer, and there is a fault that it is not mixed uniformly. A polymer having a glass transition temperature exceeding 0 ° C. has a small effect of imparting flexibility, and it is necessary to increase the plasticizer, and the amount of n-heptane extracted from the stretch film after film formation increases. A more preferable range of Tg is -90 ° C to -20 ° C. Similarly, when the copolymerization ratio is less than 5% by mass, the effect of imparting flexibility is small, and when it exceeds 50% by mass, the powder characteristics are deteriorated and handling is difficult. A more preferable range is 15 to 45% by mass.
Examples of such acrylic polymers include homopolymers of alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, alkyl acrylate copolymer obtained by combining two or more of these alkyl acrylates, and refractive index adjustment. Alternatively, an alkyl acrylate copolymer obtained by copolymerizing styrene can be used.
If the degree of polymerization of the vinyl chloride portion of the present vinyl chloride copolymer is less than 600, the mechanical strength is inferior, and if it exceeds 1500, the melt viscosity increases and the molding process becomes difficult. A more preferable range is 700 to 1400.

As the vinyl chloride resin used as the component (B), those having a polymerization degree of 800 to 1300 can be suitably used. If the degree of polymerization is less than 800, the mechanical strength tends to be inferior, and if it exceeds 1300, heat is generated with an increase in melt viscosity, and a burnt color due to decomposition tends to occur. The degree of polymerization of the component (B) is preferably close to the degree of polymerization of the component (A) to be blended. Specifically, the difference in the degree of polymerization of the component (A) and the difference in the degree of polymerization of the component (B) is preferably ± 500. This is because when the difference in the degree of polymerization is larger than ± 500, the gelation rate is different and tends to cause unmelted spots such as fish eyes. More preferably, it is within ± 300.
The polyvinyl chloride resin of the component (B) includes a vinyl chloride homopolymer, a copolymer with a monomer copolymerizable with vinyl chloride (hereinafter referred to as a vinyl chloride copolymer), Examples include graft copolymers obtained by graft-copolymerizing vinyl chloride to polymers other than vinyl chloride copolymers, and these copolymers have an increased content of constituent units other than vinyl chloride in the copolymer. Since mechanical properties are deteriorated, it is preferable to contain 60% by mass or more of vinyl chloride. Each polymer may be obtained by any polymerization method such as emulsion polymerization method, suspension polymerization method, solution polymerization method, bulk polymerization method, etc., each used alone or in combination of two or more polymers. Is done.

  As the monomer copolymerizable with vinyl chloride, any monomer having a reactive double bond in the molecule may be used. For example, α-olefins such as ethylene, propylene, butylene; vinyl acetate, propionic acid Vinyl esters such as vinyl; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; aromatic vinyls such as styrene and α-methylstyrene; vinyl halides such as vinylidene chloride and vinyl fluoride; N-phenylmaleimide, N- N-substituted maleimides such as cyclohexylmaleimide; and the like, and these are used singly or in combination of two or more. The polymer other than the vinyl chloride copolymer may be any polymer that can be graft copolymerized with vinyl chloride, such as an ethylene / vinyl acetate copolymer, an ethylene / vinyl acetate / carbon monoxide copolymer, Ethylene / ethyl acrylate copolymer, ethylene / ethyl acrylate / carbon monoxide copolymer, ethylene / methyl methacrylate copolymer, ethylene / propylene copolymer, acrylonitrile / butadiene copolymer, polyurethane, chlorinated polyethylene, chlorinated Polypropylene etc. are mentioned, These are used individually by 1 type or in combination of 2 or more types.

Here, the added amount of the component (A) is 10 to 90 parts by mass, the added amount of the component (B) is 90 to 10 parts by mass, and the combined amount of (A) and (B) is 100 parts by mass. When the addition amount of the component (A) is less than 10 parts by mass (that is, the addition amount of the component (B) is more than 90 parts by mass), the effect of imparting flexibility and the effect of decreasing the melt viscosity is small. If the added amount exceeds 90 parts by mass (that is, the added amount of the component (B) is less than 10 parts by mass), the plasticizer absorbability deteriorates and the thermal stability also deteriorates, so more preferably 15 to 85 parts by mass. Part.
The adipate ester plasticizer used as the component (C) is a single adipate ester plasticizer having a C10 or less alkyl group alone or a mixture of two or more aliphatic alcohols and adipic acid. Examples of the acid ester plasticizer include diisononyl adipate: DINA (having 9 carbon atoms), dioctyl adipate: DOA (having 8 carbon atoms), and examples of the mixed adipate ester plasticizer include C8,10 adipate ( Mixed esters of alcohols having an alkyl group having 8 or 10 carbon atoms), C7,8 adipate (7,9), C6,8,10 adipate (6,8,10), and the like. It is used individually by 1 type or in combination of 2 or more types.
Adipic acid-based polyester plasticizer is a reaction product of adipic acid and a dihydric alcohol. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, butanediol, and 1,6-hexanediol. Reaction products with two or more dihydric alcohols, specifically poly (propylene glycol, adipic acid) ester, poly (butanediol, adipic acid) ester, poly (ethylene glycol, adipic acid) ester, poly (1,6-hexanediol, butanediol, adipic acid) ester, poly (butanediol, ethylene glycol, adipic acid) ester, poly (ethylene glycol, propylene glycol, butanediol, adipic acid) ester and the like. An average molecular weight of 1000 to 3000 is effectively used, but if it is less than 1000, the resistance to extraction with n-heptane is low. On the other hand, when the average molecular weight exceeds 3000, the extrusion moldability is significantly lowered, and furthermore, the cold resistance of the stretch film is lowered. Furthermore, those having an average molecular weight of about 2000 are preferably used in terms of improvement in physical properties and extrusion moldability.

  The addition amount of the adipic acid ester plasticizer and / or polyester plasticizer as the component (C) is 5 to 30 parts by mass. If the amount is less than 5 parts by mass, the resulting film is not imparted with appropriate slipperiness. For example, the film may not be smoothly conveyed when it is applied to an automatic packaging machine, or may be broken due to necking at the corner of the tray. Occur. Moreover, when it exceeds 30 mass parts, there exists a problem that the amount of n-heptane extraction becomes too large. A more preferable range of the addition amount is 10 to 25 parts by mass.

  (D) The addition amount of the epoxy-type plasticizer used as a component is 1-15 mass parts. The epoxy plasticizer plays a role as a heat stabilizer adjuvant (heat safety aid) in addition to the role as a plasticizer. If it is less than 1 part by mass, it does not play a role as a heat safety aid. If the amount exceeds mass parts, the amount of n-heptane extracted and coloring will occur. In consideration of these, a more preferable range is 3 to 13 parts by mass. Epoxy plasticizers that can provide such effects include epoxidized soybean oil (ESBO), epoxidized linseed oil (ELSO), and the like.

The Ca—Zn stabilizer used as the component (E) is a mixture of a fatty acid salt of calcium and a fatty acid salt of zinc, and the addition amount is 0.1 to 2.0 parts by mass. If it is less than 0.1 parts by mass, the effect of thermal stability is not exhibited, and if it exceeds 2.0 parts by mass, rapid decomposition called zinc burn occurs. More preferably, it is 0.3-1.8 mass parts.
Examples of the fatty acid that forms a salt with calcium and zinc used in the present invention include behenic acid, stearic acid, lauric acid, oleic acid, palmitic acid, ricinoleic acid, benzoic acid, and the like. Although it can also be used, it is preferable to use a stearate from the balance between the slipperiness at the time of molding and the plate-out. Moreover, the ratio of calcium and zinc is 1: 2 to 1: 3 by mass ratio. If the ratio of zinc is less than 2, the redness peculiar to calcium salts will appear. If the ratio of zinc is more than 3, the zinc chloride produced during molding will be vinyl chloride resin. As a decomposition catalyst, rapid blackening and decomposition called “zinc burn” occur.

The ester of polyhydric alcohol and fatty acid used as the component (F) generally acts as an antifogging agent, and the addition amount is 0.1 to 5.0 parts by mass. If it is less than 0.1 parts by mass, the anti-fogging property is not exhibited, and for example, when a food container or the like is packaged and stored, water drops are generated on the film, and the contents cannot be confirmed. If it exceeds the area, the film surface will become sticky, and when applied to an automatic wrapping machine, the friction of the film with the conveyor belt will be low, causing a problem that it will be too slippery to convey. A more preferable range is 1.0 to 3.5 parts by mass. Examples of such polyhydric alcohol and fatty acid esters include monoglycerin fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters, and polyoxyethylene alkyl ethers. The monoglycerin fatty acid ester is preferably a monoglycerin ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms. Specific examples include monoglycerol laurate, monoglycerol myristate, monoglycerol palmitate, monoglycerol stearate, monoglycerol oleate, and monoglycerol linoleate. As the polyglycerol fatty acid ester, a polyglycerol ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms is preferable. Specific examples include polyglycerol laurate, polyglycerol myristate, polyglycerol palmitate, polyglycerol stearate, polyglycerol oleate, and polyglycerol linoleate. The sorbitan fatty acid ester is preferably a sorbitan ester of a saturated or unsaturated fatty acid having 12 to 18 carbon atoms. Specific examples include sorbitan laurate, sorbitan myristate, sorbitan palmitate, sorbitan stearate, sorbitan oleate, sorbitan renolate and the like. The polyoxyethylene alkyl ether is preferably a saturated alcohol polyoxyethylene alkyl ether having 12 to 18 carbon atoms, more preferably a polyoxyethylene alkyl ether having 3 to 7 added moles of ethylene oxide. Specific examples include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene palmityl ether, polyoxyethylene stearyl ether, and the like. These may be used alone or in combination of two or more.

In addition, an ultraviolet absorber, an antioxidant, an antibacterial / antifungal agent, a processing aid, a lubricant, a colorant, a filler, a refractive index adjusting agent, and the like may be added as long as the above-described effects are not impaired.
The vinyl chloride resin composition in the present invention can be obtained by putting the above-described polymer and additives into a commonly used mixing apparatus such as a super mixer, and heating, stirring and cooling. The heating temperature and stirring time may be determined while observing the mixing state from a monitoring window or the like, but more preferably, the temperature is raised to 100 ° C. to 130 ° C. while stirring at high speed, and when reaching the target temperature, switching to low speed stirring is performed. When cooled to about 60 ° C., a compound with good powder flowability can be obtained.
The formation of the stretch film in the present invention is obtained by forming the obtained compound into a film by a T-die method or an inflation method using a single-screw, twin-screw, or multi-screw extruder.

Hereinafter, although the effect of the present invention is explained in detail based on an example, the present invention is not limited to the following examples.
Each compounding agent was put into a super mixer and stirred at the blending ratio shown in the table, heated to 130 ° C, cooled to 60 ° C, and then taken out to obtain a vinyl chloride resin composition.
The contents of the raw materials used are as follows.
・ Straight PVC: “TK-1000” (manufactured by Shin-Etsu Chemical Co., Ltd.)
BA copolymerized PVC: PVC obtained by graft copolymerization of acrylic polymer (BA) having a Tg of −60 ° C. with the content (% by mass) shown in Table 1.
・ Diisononyl adipate: “Sanso Sizer DINA” (manufactured by Shin Nippon Rika Co., Ltd.)
Poly 1,3-butanediol adipate (polyester plasticizer): “BAA-15” (manufactured by Daihachi Chemical Industry Co., Ltd.)
-Epoxidized soybean oil: "Capox S-6" (manufactured by Kao Corporation)
Ca-Zn stabilizer: “ADK STAB SP-76” (Asahi Denka Kogyo Co., Ltd.)
・ Oleic acid mono-diglyceride: “Excel 300” (manufactured by Kao Corporation)
The obtained resin composition was extrusion-molded at a resin temperature of 200 ° C. with a φ40 mm single screw extruder (L / D = 20) equipped with a T die (width 350 mm, gap 0.4 mm) to obtain a film. . The obtained film was evaluated as follows, and the results are shown in Table 1.

[Appearance evaluation]
-Visually determine the appearance of the extruded film according to the following criteria: Good transparency. No color problem. No stuff.
Δ: Transparency is slightly inferior. The color is slightly reddish. There are stuff.
X: Inferior in transparency. The color is burnt red. Many

[Food hygiene test]
-N-Heptane extraction test: The extraction amount was measured by the evaporation residue test method defined in the Ministry of Health and Welfare Notification No. 20 in 1982 and indicated as n-heptane extraction amount (ppm) (50 mass ppm or less: ○, 50 mass ppm Super: x).
[Packaging aptitude]
Appropriateness of automatic packaging machine: Eight shishamo were put on a PP tray, and automatic packaging was carried out at a packaging speed of 40 packs / min by an automatic packaging machine “A-18K” manufactured by Fujikikai, and packaging suitability was evaluated according to the following criteria.
What can be packaged without wrinkles or tears: ○
Somewhat slippery but packaged: △
Wrinkles, tears and unsuitable packaging: ×

It can be seen from Table 1 that Examples 1 to 7 are excellent in all the characteristics of film appearance, n-heptane extract amount, and packaging suitability.
On the other hand, in Comparative Example 1 in which the amount of component (A) is too small, the melt viscosity was too high and the film was burnt, and a sample for measuring physical properties could not be employed. Similarly, in Comparative Example 2 in which the amount of the component (A) is small and the plasticizer component (C) is increased to give flexibility, the amount of elution of n-heptane is large. (A) In Comparative Example 3 in which the amount of the component was too large, the raw material was dumped in the mixer during film production, and film production was impossible. In Comparative Example 4 in which the amount of the component (A) is within the range of the present invention and the amount of the component (C) is large, the n-heptane elution amount is large and the packaging suitability is poor. Further, in Comparative Example 5 in which the amount of the component A) was within the range of the present invention and the amount of the component (C) was too small, the film was burnt and a sample for measuring physical properties could not be employed.

The stretch film of the present invention is composed of a polyvinyl chloride resin composition having a specific composition, and is excellent in properties for food packaging despite being thin, and further, n- as defined in Ministry of Health and Welfare Notification No. 20 It is suitable for use as a food packaging film because it has a small amount of heptane extract and therefore has a low migration of plasticizers to fatty foods.

Claims (3)

Polymerization of a vinyl chloride portion obtained by graft copolymerizing 5 to 50% by mass of an acrylic polymer comprising (A) and (B) as a polymer component and (A) having a glass transition temperature (Tg) of −100 to 0 ° C. 10 to 90 parts by mass of a vinyl chloride copolymer having a degree of 600 to 1500,
(B) 90-10 parts by mass of vinyl chloride resin,
(A) + (B) = 100 parts by mass,
(C) 5-30 parts by mass of an adipic acid ester plasticizer and a polyester plasticizer,
(D) 1 to 15 parts by mass of an epoxy plasticizer,
(E) 0.1 to 2.0 parts by mass of a Ca—Zn stabilizer,
(F) 0.1 to 5.0 parts by mass of an ester of a polyhydric alcohol and a fatty acid,
A vinyl chloride resin composition comprising: Acrylic polymer is an alkyl acrylate polymer and / or alkyl acrylate copolymer comprising a polymer according to claim 1 Symbol placement of the vinyl chloride resin composition. It is a stretch film formed by using the vinyl chloride resin composition according to claim 1 or 2 and having a thickness of 6 to 12 μm according to an evaporation residue test method defined in Ministry of Health and Welfare Notification No. 20 of 1982. A stretch film having a measured n-heptane extraction amount of 50 ppm or less.