JP2859285B2 - Packaging material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a packaging material such as a container having excellent heat sealability, flexibility, pinhole resistance, fragrance retention, and impact resistance. More specifically, the present invention relates to a heat-sealing packaging material for directly filling or packaging a food or the like containing an aroma component.

[Related Art] In the field of food and beverage packaging such as juice containers, the usage ratio of synthetic resin containers or resin-coated paper containers is rapidly increasing. As the resin used for this purpose, olefin polymers are widely used from the viewpoint of heat sealing properties, flexibility and the like. However, olefin polymers have drawbacks in gas barrier properties and fragrance retention properties, and when used as an inner layer resin that comes into direct contact with foods and beverages having fragrance components, there is a drawback that the taste and aroma change.

Polyethylene terephthalate (hereinafter referred to as PET) is excellent in fragrance retention, but cannot be heat-sealed, and thus is unsuitable as the resin for food and drink containers or the inner layer resin for coating paper containers as described above. On the other hand, blending a small amount of ethylene-based resin with PET improves flexibility and heat-sealing properties.However, when filling the contents at a high temperature, there is a drawback that if the time from filling to sealing becomes longer, the heat-sealing properties deteriorate. Therefore, it could not be said to be satisfactory for high-temperature filling.

Modified PET, which contains a considerable amount of a copolymer component such as isophthalic acid, is superior to PET in heat sealability, but is inferior in flexibility and pinhole resistance. It was unsuitable for use as a paper container inner layer material.

[Problems to be Solved by the Invention] The present inventors have studied a packaging material using a new material that does not have the above-mentioned disadvantages by taking advantage of the excellent fragrance retention and heat sealing properties of the modified PET. As a result, modified PE
It has been found that a composition in which T and a specific ethylene copolymer are blended at a fixed ratio is suitable for use as a packaging material. It is therefore an object of the present invention to provide a new packaging material based on modified PET. Another object of the present invention is that it can be sufficiently used for high-temperature filling when used as a container or a paper container inner layer material, and has a heat sealing property, a scent retention property,
An object of the present invention is to provide a packaging material having excellent pinhole resistance.

Means for Solving the Problems The present invention relates to (1) 60-90 parts by weight of a modified polyethylene terephthalate containing 5-20 mol% of a copolymer component, and (2) ethylene / (meta) having an ester content of 5-40% by weight. A) A packaging material in which a modified polyester composition layer composed of 10 to 40 parts by weight of an acrylate-based copolymer is used as a heat seal layer.

(In the present invention, the (meth) acrylate means an acrylate or a methacrylate. The same shall apply hereinafter.) The modified PET (1) used in the present invention comprises, in addition to an ethylene glycol unit and a terephthalic acid unit, The copolymerization component is copolymerized at a ratio of 5 to 20 mol%, preferably 5 to 15 mol%. As copolymerization components, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, p-
Aromatic carboxylic acids such as oxybenzoic acid, adipic acid, sebacic acid, aliphatic or alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, propylene glycol,
Examples include diols such as 1,4-butanediol, 1,4-cyclohexanedimethanol, diethylene glycol, and triethylene glycol. Among these copolymer components, isophthalic acid, 1,4-cyclohexanedimethanol, diethylene glycol and the like are particularly preferred.
These modified PETs have an intrinsic viscosity of 0.60 to 1.4 dl /
g, particularly preferably 0.7 to 1.0 dl / g.

When the amount of the copolymer component is less than 5 mol%, the heat sealability is poor, and a material having a high heat seal strength cannot be obtained for use as an inner layer material of a high-temperature filling paper container. On the other hand, when the amount of the copolymer component exceeds 20 mol%, the flexibility and elongation of the composition are not sufficient, and breakage or the like due to pinholes or bending tends to occur.

The ethylene / (meth) acrylate-based copolymer used in the present invention is a copolymer containing an ethylene and (meth) acrylate having an ester content of 5 to 40% by weight, preferably 10 to 30% by weight, as essential components. Polymer and 20 other
It may be a multi-component copolymer containing not more than about by weight of a copolymer component.

Here, as the (meth) acrylate, ethyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl acrylate, glycidyl methacrylate And the like.

Further, as other copolymerization components, acrylic acid, methacrylic acid, maleic anhydride, monomethyl maleate, unsaturated carboxylic acids such as monoethyl maleate or anhydrides thereof, salts of these unsaturated carboxylic acids, for example, sodium,
Examples thereof include salts of metals such as lithium, potassium, calcium, magnesium, zinc, and aluminum, vinyl acetate, other esters such as diethyl maleate, and carbon monoxide. When a part of the unsaturated carboxylic acid is a metal salt neutralized with a metal ion, the copolymer is an ionomer of a terpolymer composed of ethylene / (meth) acrylate / unsaturated carboxylic acid, It can be preferably used as the ethylene / (meth) acrylate-based copolymer of the present invention. In such an ionomer, acrylic acid or methacrylic acid is generally used as the unsaturated carboxylic acid, and zinc and sodium are particularly preferable as the metal. The degree of neutralization is preferably 5 to 80%, particularly preferably 10 to 70%.

As such an ethylene copolymer, 190 ° C, 2160 g
Melt flow rate under load is 0.05-100g / 10min,
In particular, those having a concentration of 0.1 to 50 g / 10 minutes are preferable.

In the present invention, the mixing ratio of the modified PET (1) and the ethylene copolymer (2) in the composition is 100
Parts by weight, the modified PET (1) is 60 to 90 parts by weight, preferably 70 to 85 parts by weight, and the ethylene copolymer (2) 10
To 40 parts by weight, preferably 15 to 30 parts by weight. If the modified PET exceeds the above range, flexibility, pinhole resistance and the like are inferior and are unsuitable as a packaging material.
If the amount of the ethylene copolymer exceeds the above range, the fragrance retention, gas barrier properties, heat resistance and the like will be reduced, and its use as a packaging material that comes into direct contact with foods and beverages having an aroma component will be limited.

In the present invention, up to 10 parts by weight of another ethylene-based polymer may be added to 100 parts by weight of the total of the modified PET (1) and the ethylene copolymer (2). Examples of the ethylene-based polymer include high-density or low-density polyethylene, a main amount of ethylene and an α-olefin having about 3 to 12 carbon atoms, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecane, copolymers of various densities with 4-methyl-1-pentene, etc., copolymers of a major amount of ethylene and a polar vinyl monomer and / or carbon monoxide, and these as base polymers, Examples thereof include a copolymer obtained by grafting a polar vinyl monomer. Two or more of these copolymer component monomers may be used in combination to form a ternary or higher multi-component copolymer. Examples of the polar vinyl monomer include carboxylic acid unsaturated esters such as vinyl acetate and vinyl propionate.

As such an ethylene polymer, 190 ° C, 2160
Melt flow rate at g load is 0.1-100g / 10min,
In particular, the one with 0.3 to 50 g / 10 minutes is preferable.

Additives such as an oxidation stabilizer, a slip agent, an anti-blocking agent, and a coloring agent can be appropriately added to the composition of the present invention.

The present invention is a single-layer or multilayer packaging material having at least the resin composition layer as a heat seal layer. That is, the packaging material of the present invention can be used as a single-layer resin container molded only with the above resin composition, but is laminated on another material and used in such a configuration that the resin composition of the present invention is used as an inner layer. be able to. Other materials that can be laminated include metal, paper, various thermoplastics, such as PE
T, polyamide, polycarbonate, ethylene / vinyl alcohol copolymer, polyvinylidene chloride, polyolefin and the like can be exemplified by one or more layers.
In such a multilayer packaging material, the composition layer of the present invention can be used in a thickness of, for example, 10 to 200 μm. In the present invention, in the case of a single layer, in any case of the multilayer, the composition layer having excellent fragrance retention, heat sealing properties, etc. is heat-sealed and molded, and the resin composition layer comes into direct contact with food and drink, It is suitable as a container for food and drink or the like containing an aroma component.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 75% by weight of modified polyethylene terephthalate (isophthalic acid / terephthalic acid / ethylene glycol = 10/40/50) containing 10 mol% of isophthalic acid and Zn ionomer of ethylene-isobutyl acrylate-methacrylic acid copolymer (10% by weight of isobutyl acrylate) %, Methacrylic acid 10% by weight, neutralization degree 60 ° C.) 25% by weight were mixed and granulated at 270 ° C. by a 30 mmφ biaxial kneader in the same direction. Before the mixing and granulating operation, each resin was sufficiently dried with heated nitrogen. The granulated mixture was dried again and formed into a film at a blow-up ratio of 2.0 and a resin temperature of 265 ° C. using a 30 mmφ inflation molding machine. The thickness of the film was 40 μm.

The tensile stress at break and elongation at break of this film were measured. Table 2 shows the results. Further, this film was heat-sealed with a bar sealer manufactured by Toyo Seiki, and the peel strength was measured. At the same time, another portion of the same film was immersed in hot water at 75 ° C. for 3 minutes, dried, heat-sealed in the same manner, and the strength was measured. Table 3 shows the heat seal strength before and after the hot water treatment.

Further, this film was cut into 3 cm × 3 cm, immersed in a 100% solution of D-limonene, and allowed to stand at room temperature. After a predetermined time, the film was taken out, the surface was quickly wiped with filter paper, the weight of the film was measured, and the weight increase due to the absorption of limonene into the film was measured. The results are shown in Table-4.

Examples 2 to 3, Comparative Examples 1 to 3 Modified polyethylene terephthalate containing 10 mol% of isophthalic acid and an enlenic copolymer were used as raw materials in proportions shown in Table 1, and mixed in the same manner as in Example 1 to obtain physical properties. Was evaluated. The results are shown in Table 2, Table 3, and Table 4 together with Example 1.

From the results of Table 2, Table 3, and Table 4, the resin composition used in the packaging material of the present invention not only has excellent heat sealability and heat seal strength, but also has excellent flexibility and an aroma component. It is understood that it is a material suitable as a resin for the inner layer of a container for high-temperature filling of foods and drinks containing a fragrance component because it has a low absorption of odor and is excellent in fragrance retention and gas barrier properties.

[Effects of the Invention] According to the present invention, by using a resin composition in which modified PET and a specific ethylene copolymer are blended in a specific ratio, gas barrier properties, fragrance retention properties, heat sealing properties, and pin resistance are achieved. A packaging material having excellent hole properties and impact resistance can be obtained. The packaging material of the present invention is used as it is for the resin composition of the above-mentioned composition as it is, or is used for the part directly in contact with food and drink by laminating with other materials. By this method, pinholes and tears do not occur, and sufficient heat sealing strength can be maintained even when the contents are filled at a high temperature. And, since the property of adsorbing the fragrance component such as limonene is slight, even when the fragrance component-containing food or drink such as orange juice is filled, the change over time in taste, fragrance and the like is small.

Claims (2)

(57) [Claims] 1. An ethylene / (meth) acrylate copolymer having (1) 60 to 90 parts by weight of a modified polyethylene terephthalate containing 5 to 20 mol% of a copolymer component and (2) an ester content of 5 to 40% by weight. A packaging material comprising a modified polyester composition layer consisting of 10 to 40 parts by weight of a heat-sealing layer. 2. A packaging material for use as a heat-sealing layer, comprising a modified polyester composition further comprising 10 parts by weight or less of another ethylene-based polymer per 100 parts by weight of the total amount of the modified polyester composition according to claim 1.