JP4944448B2 - Food packaging material - Google Patents

Description

  The present invention relates to a packaging material comprising an ionomer composition excellent in UV-cutting or absorption, particularly a packaging material suitable for food packaging, and more specifically, an ionomer of a specific metal species and an ultraviolet absorber having a specific chemical structure. The present invention relates to a packaging material comprising a combined composition, and particularly excellent as a food packaging material, which is excellent in long-term sustainability of ultraviolet ray cutting or absorption function.

An ionomer of an ethylene / (meth) acrylic acid copolymer is widely used as a packaging material for various articles because it is excellent in transparency, heat sealability, hot tackiness and the like.
However, since it has passed the regulations as the US FDA and Japanese food packaging materials, food packaging materials such as vacuum packaging films for meat, liquids, etc. as single films or laminated films with other resins, etc. It has been widely used for packaging bags, dry / powder food packaging, snack foods, skin packaging, and the like.

In recent years, in the field of packaging materials, UV rays have been cut from the viewpoint of avoiding deterioration of the surface condition of the packaged items and color deterioration of the cover pattern, and especially in the case of food packaging materials, from the viewpoint of maintaining the freshness of the packaged items.・ There is a tendency to strongly demand materials to be absorbed.
As a relatively easy method for achieving this, a method of applying an ultraviolet absorbent having a function of absorbing ultraviolet rays to the surface of the packaging material, or kneading into a material resin or a resin composition is conceivable.
In fact, the packaging material is not a direct object. However, from the viewpoint of improving its heat resistance and weather resistance, Patent Document 1 discloses that a benzophenone-based and / or benzophenone-based polyolefin resin or ethylene copolymer is used. A composition containing a triazole-based ultraviolet absorber, a hindered phenol, a hindered amine and the like is disclosed.
Also, in Patent Document 2, an ethylene / (meth) acrylic acid copolymer or its ionomer is added with a benzotriazole-based or triazine-based UV absorber together with a hindered phenol or hindered amine from the viewpoint of improving weather resistance. A proposed composition has been proposed.
JP-A-2003-192846 JP 2001-261904 A

  However, general-purpose plastics such as polyethylene and ethylene-based copolymers lack the ability to hold UV absorbers with high polarity and low molecular weight for a long period of time, and they are kneaded almost uniformly immediately after the packaging material is manufactured. Even if it is rarely dispersed and can exhibit a predetermined effect, its effectiveness gradually decreases due to bleeding over time, etc., and after a certain period of time has passed since manufacture, the ultraviolet ray cutting or absorption function is significantly reduced. Therefore, the inconvenience that the purpose cannot be achieved occurred.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a combination of a specific metal species ionomer and a UV absorber having a specific chemical structure is effective in solving the above-mentioned problems. Completed the invention.
Accordingly, an object of the present invention is to make a resin composition excellent in retention of ultraviolet absorbers, and to maintain freshness of packaged foods and the like without deterioration in ultraviolet absorption cut performance even for long-term storage or use. To provide excellent food packaging materials.

According to the present invention, Ri Do zinc or magnesium ion source and the ethylene (meth) composition containing benzotriazole-based ultraviolet absorbents ionomer of acrylic acid copolymer, wherein the composition the ionomer 100 food packaging having the composition der Ru ultraviolet absorption function containing a combination of the ultraviolet absorber 0.02 to 2 parts by weight is provided for parts by weight.

The present invention, active ingredient a compound of a particular ionomer and benzotriazole specific chemical structure as a material for packaging material, zinc or magnesium the ionic species in order to ultraviolet absorption function food packaging long stably maintained A feature of the constitution is that a resin composition in combination with a specific amount of the ultraviolet absorber is selected and used.
This resin composition of the present invention is remarkably excellent in the long-term stability retention of an ultraviolet absorber, for example, compared to a resin composition in which an ultraviolet absorber is blended with sodium or potassium ionomer of ethylene / (meth) acrylic acid copolymer, Even after long-term storage or use as a packaging material, excellent UV-cutting and absorption effects are sustained.

Before SL ultraviolet absorber is preferably 2 (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chloro-benzotriazole.

  Moreover, according to this invention, the food packaging material which consists of a laminated body by which the layer which consists of a precomposition was laminated | stacked at least 1 layer is provided.

The food packaging material of the present invention is made of a resin composition in which a specific amount of a benzotriazole-based ultraviolet absorber is combined with a specific ionomer having zinc or magnesium as an ionic species, for example, ethylene (meth). Compared to packaging materials made of resin composition materials other than the present invention in which ultraviolet absorbers are blended with sodium or potassium ionomers of acrylic acid copolymers, the ultraviolet absorbers are significantly superior in long-term stability and long-term packaging materials. Even after storage or use, excellent UV-cutting and absorption effects are sustained.

Hereinafter, embodiments of the present invention will be described in detail and specifically.
The present invention is an invention of a food packaging material comprising a composition in which a specific amount of a benzotriazole-based ultraviolet absorber is blended with an ethylene / (meth) acrylic acid copolymer ionomer containing zinc or magnesium as an ion source.

  In the present invention, the ethylene / (meth) acrylic acid copolymer constituting the resin component of the ionomer is a copolymer of ethylene and acrylic acid or methacrylic acid, and only ethylene and acrylic acid or methacrylic acid. It may consist of, or may be copolymerized with other monomers.

  Examples of the other monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, nbutyl acrylate, isobutyl acrylate, -2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid. Examples thereof include n-butyl acid, isobutyl methacrylate, 2-ethylhexyl methacrylate, dimethyl maleate and other unsaturated carboxylic acid esters, vinyl acetate such as vinyl acetate, and carbon monoxide.

  The (meth) acrylic acid content in the ethylene / (meth) acrylic acid copolymer is 3 to 2.5% by weight, preferably 3 to 20% by weight, and the other monomer content is 0 to 0%. 20% by weight, preferably 0 to 15% by weight.

In the present invention, the metal as the cation species used for ionomer formation must be zinc or magnesium , and the use of a monovalent metal such as potassium or sodium or a trivalent or higher polyvalent metal species such as aluminum is used. This is not preferable because the long-term retention of a benzotriazole-based ultraviolet absorber described later is not good .
Also, the ionomer may be used in combination of two or more thereof.
The degree of neutralization by the upper Kikin genus ions in the ionomer is 5 to 100%, preferably 5 to 80%.

  The molecular weight of the ethylene / (meth) acrylic acid ionomer used in the present invention is not particularly limited and is appropriately selected depending on the use as a packaging material. For example, the melt flow rate at 190 ° C. under a load of 2160 g ( MFR) of 0.01 to 200 g / 10 min, particularly 0.1 to 100 g / 10 min can be preferably used.

UV absorbers used in the present invention are selected from those of the base benzotriazole system.

  The benzotriazole ultraviolet absorber is a hydroxy-substituted benzotriazole compound, for example, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) benzotriazole 2- (2-hydroxy-3,5-dimethylphenyl) benzotriazole, 2- (2-methyl-4-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-3-methyl-5-tert-butylphenyl) ) Benzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2 -Hydroxy-3,5-dimethylphenyl) -5-methoxybenzotriazole, 2- (2 n-octadecyloxy-3,5-dimethylphenyl) -5-methylbenzotriazole, 2- (2-hydroxy-5-methoxyphenyl) -5-methylbenzotriazole, 2- (2-hydroxy-3-t-butyl- 5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-phenylphenyl) -5-chlorobenzo Triazole, 2- (2-hydroxy-3,5-dichlorophenylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-5-methylphenyl) -5,6-dichlorobenzotriazole, 2- (2-hydroxy -3,5-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2- Droxy-4,5-dichlorophenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3-methylphenyl) -5-butoxycarbonylbenzotriazole, 2- (2-acetoxy-5-methylphenyl) benzotriazole, 2- [2-Hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2Hbenzotriazole, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4 , 5,6-tetrahydrophthalimidylmethyl) phenol.

A composition as a material constituting the food packaging material of the present invention is a composition in which a predetermined amount of the benzotriazole-based ultraviolet absorber is blended with an ethylene / (meth) acrylic acid copolymer ionomer using zinc or magnesium as an ion source. It made, but the amount thereof is over the previous SL ionomer 100 parts by weight, preferably from 0.02 to 2 parts by weight in terms of overall balance of the ultraviolet absorbing function or its long-term stability lasting resistance.

In such a composition, any additive such as an antioxidant, a weather resistance stabilizer, an antistatic agent, a slip agent, a pigment, and a crosslinking agent may be used depending on the purpose as long as the ultraviolet absorbing function of the present invention is not impaired. Further, a foaming agent, a tackifier, an inorganic filler and the like can be further blended.
In addition, other polymer resins can be arbitrarily blended with the composition as long as they do not impair the ultraviolet absorption function or the function originally required as a food packaging material.

The composition of the present invention can be prepared by melt mixing using a melt kneader such as an extruder.
Molding of the composition into a food packaging material may be performed immediately after melt mixing, or may be formed into pellets after melt mixing and then molded with another melt molding machine.

The food packaging material of the present invention can have various shapes such as a film, a sheet, a tube, and a hollow container.
The thickness of these food packaging materials is not necessarily limited, and is appropriately determined depending on the molding type and its use. For example, in the case of a single-layer film, the thickness of the composition layer in other cases is, for example, about 5 to 300 μm. It can be 5 to 500 μm.

Since the molding processability of this composition is good, a packaged product can be molded by, for example, an inflation method or a T-die casting method.
Such a packaging material can be stretched uniaxially or biaxially, or can be processed such as deep drawing.

Such a packaging material is not only a single layer film, sheet, etc. made of the composition of the present invention, but also a laminate in which another layer is formed on one or both sides of the composition layer. As such other layers, a transparent or translucent polymer resin layer, a transparent or translucent paper layer and the like can be preferably exemplified.
Such other layers may of course be single layers or multiple layers.

  For example, as the polymer resin layer, polyolefin resin, styrene resin, polyamide, polyester, polycarbonate, polyacetal, polymethyl methacrylate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyolefin elastomer One type or a combination of two or more types of various rubbers can be exemplified.

  More specifically, high-pressure polyethylene, linear medium / low density polyethylene, polyethylene produced with a metallocene catalyst, high density polyethylene, polypropylene, polypropylene produced with a metallocene catalyst, poly-1-butene Poly-4-methyl-1-pentene, ethylene / vinyl acetate copolymer, ethylene / unsaturated carboxylic acid ester and the like can be exemplified as representative examples.

The styrene resin is a homopolymer or copolymer of styrene, and typical examples thereof include ABS resin and polystyrene.
Here, the ABS resin is a generic term for rubber-reinforced styrene polymers synthesized by various production methods such as a blending method, a grafting method, or a graft-blending method. Polybutadiene, styrene-butadiene rubber, ethylene Representative examples include those obtained by graft-polymerizing styrene and other monomers such as acrylonitrile, methyl methacrylate, α-methylstyrene, ethylene bisimide, and maleimide on a rubber component such as propylene / diene rubber.

  Polystyrene is a general term for general-purpose polystyrene synthesized by production methods such as suspension polymerization and continuous polymerization, as well as impact-resistant polystyrene obtained by graft polymerization of styrene to a rubber component such as butadiene rubber. To do.

  A base material having gas barrier properties is used as a freshness-maintaining packaging material, and it is considered that it becomes a more effective technique when laminated with these base materials. In such a gas barrier material, as polyamide, nylon 6, nylon 66, nylon 6, 66, nylon 11, nylon 12, nylon 6T, 6I, etc., polyester as polyethylene terephthalate, polybutylene terephthalate, polyester elastomer, and their ceramic vapor deposition Examples of materials, specifically silica, alumina vapor deposition, ethylene vinyl alcohol copolymer, and the like can be given.

Examples of the transparent or translucent paper layer include a cellophane paper layer and a translucent trace paper layer. Examples of the layer structure include the composition layer of the present invention / cellophane paper.
The packaging material obtained by molding the composition of the present invention can be suitably used for uses other than food packaging, for example, packaging for precision equipment such as decorative packaging and electronic equipment.

The present invention will be specifically described below with reference to examples.
In addition, the raw material (ionomer, ultraviolet absorber) property of each composition used for the sample film of an Example and a comparative example is as follows.

"Ionomers and polymers"
Ionomer 1: 15% by weight of methacrylic acid, metal species Zn (degree of neutralization 59%), MFR 0.9 g / 10 min. Ionomer 2: 15% by weight of methacrylic acid content, metal species Mg (degree of neutralization 54%), MFR 0.7 g / 10 min. Ionomer 3: 11.5 wt% methacrylic acid content, metal species K (neutralization level 82%), MFR 0.4 g / 10 min. Ionomer 4: 10 wt% methacrylic acid content, metal species Na (medium 50%), MFR 1.3 g / 10 min Polymer: Metallocene polyethylene (mPE) Prime Polymer Co., Ltd. SP2520 density 925 kg / cm ³ , MFR 1.9 g / 10 min

"UV absorber"
Asahi Denka Co., Ltd. Adekasta LA-36RG
Structure 2 (2'-Hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzene triazole

"Evaluation of film"
Bleed state of ultraviolet absorber: The presence or absence of bleed is visually determined from the film after a certain period of time has elapsed since film formation.
UV cut rate: UV transmittance at a wavelength of 360 nm was measured using a spectrophotometer, and 0% transmittance was defined as 100% UV cut rate.

Example 1
100 parts by weight of the ionomer 1 described in the section of “ionomer and polymer” and 0.8 parts by weight of the “ultraviolet absorber” were mixed, and a twin-screw extruder (screw diameter 30 mm, L / D = 32) was mixed. The mixture was kneaded and granulated (pelletized) at a resin temperature of 200 ° C. and an extrusion speed of 6 kg / h.
The pellet was taken up at a winding speed of 3 m / min using a single screw extruder (screw diameter 30 mm, L / D = 24) equipped with an inflation die (caliber 500 mm), and a thickness of 50 μm (folding width 200 mm). Made a film.
The obtained film was stored for a predetermined period (2 weeks, 1 month, 3 months), and the bleed state (visual observation) and UV cut rate of the ultraviolet absorber of the film were evaluated.
The results are shown in Table 1.

(Example 2)
A film was prepared in the same manner as in Example 1 except that ionomer 2 was used in place of ionomer 1 in Example 1, and evaluation was performed in the same manner as in Example 1.
The results are shown in Table 1.

(Example 3)
Using the composition pellets prepared in Example 1 and the metallocene polyethylene (mPE) pellets described in the section “Ionomers and polymers”, the layer structure (mPE / ionomer 1 / mPE: thickness ratio 1/8/1) The laminated film was produced by extrusion with a co-extruder, and the obtained laminated film was evaluated in the same manner as in Example 1.
The results are shown in Table 1.

(Comparative Example 1)
A film was prepared in the same manner as in Example 1 except that the ionomer 3 was used in place of the ionomer 1 in Example 1, and evaluation was performed in the same manner as in Example 1.
The results are shown in Table 1.

(Comparative Example 2)
A film was prepared in the same manner as in Example 1 except that the ionomer 4 was used in place of the ionomer 1 in Example 1, and evaluation was performed in the same manner as in Example 1.
The results are shown in Table 1.

(Comparative Example 3)
Evaluation was carried out in the same manner as in Example 1 using an extruded film (thickness 50 μm) of the metallocene polyethylene (mPE).
The results are shown in Table 1.

Claims (3)

Ri Do zinc or magnesium ion source and the ethylene (meth) composition containing benzotriazole-based ultraviolet absorbents ionomer of acrylic acid copolymer, wherein said composition to said ionomer 100 parts by weight UV absorber 0.02 to 2 parts by weight food packaging having the composition der Ru ultraviolet absorbing function blended. The food packaging material according to claim 1, wherein the ultraviolet absorber is 2 (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole.   A food packaging material comprising a laminate in which at least one layer of the composition according to claim 1 is laminated.