JPH0310041Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention has a flexible layer structure that has excellent moisture and oxygen barrier properties, does not cause delamination, and can withstand boiling treatment. This relates to a simple laminate. [Prior Art] Conventionally, films made of vinylidene chloride copolymers have poor gas barrier properties, strength, transparency, workability, etc.
It has excellent suitability as a packaging material, and is especially widely used in food packaging applications. However, on the other hand, it has disadvantages such as being expensive, having poor low-temperature flexibility and heat-sealing properties, and if the contents are oil-based, the plasticizer in the film may be extracted and contaminate the contents. have In order to compensate for these shortcomings, for example, as seen in Japanese Patent Publication No. 53-24464,
A laminated film of ethylene resin and vinylidene chloride resin has been devised and widely used. However, the ethylene resin referred to here is a copolymer of ethylene and vinyl acetate, etc., and these resins have poor solvent resistance, low softening point, and weak strength.
Its use was limited. Additionally, ethylene alkyl acrylate copolymer resins and styrene-butadiene copolymer resins, which were conventionally used as adhesive layer resins with vinylidene chloride, had properties similar to those of ethylene-vinyl acetate copolymers, and their applications were limited. . In addition, four- or five-layer films were devised in which ethylene-vinyl acetate copolymer or the like was used as the adhesive layer resin, and polyethylene alone was laminated on the outer layer, and the above drawbacks were improved, but the content was oil-based. If this happens, the adhesive force will decrease, and if the adhesive layer is subjected to boiling treatment, it will deform due to the low softening point of the adhesive layer, and the laminar flow required for using advanced multilayer dies will be disrupted, making it impossible to obtain a uniform laminate. There were flaws. [Purpose of the invention] As a result of research to improve the above-mentioned drawbacks, the present inventors investigated the adhesion between various adhesive resins and vinylidene chloride-based resins. Based on this knowledge, they conducted various research and completed the present invention. The objective is to provide a flexible laminate with a simple layer structure that has excellent moisture and oxygen barrier properties, does not suffer from delamination, and can withstand boiling treatment. . [Structure of the invention] That is, the invention provides a laminate in which an acid-modified olefin resin layer is arranged on one or both sides of a vinylidene chloride resin layer, and the acid-modified olefin resin is medium-density polyethylene, high-density polyethylene,
An acid-modified olefin resin made by chemically bonding linear low-density polyethylene or polypropylene with unsaturated fatty acids or their anhydrides, and has a high softening point.
It is a laminate made of resin with a temperature of 90°C or higher. The vinylidene chloride resin used in the present invention is a binary or multi-component copolymer consisting mainly of vinylidene chloride and copolymerized with vinyl chloride, alkyl acrylate, acrylic acid, acrylonitrile, and other copolymer components. In addition, the acid-modified olefin resin used in this invention includes medium density polyethylene, high density polyethylene,
Linear low-density polyethylene, polypropylene, monobasic unsaturated fatty acids such as acrylic acid, methacrylic acid, dibasic unsaturated fatty acids such as maleic acid, fumaric acid, itaconic acid, and even dibasic unsaturated fatty acids. It is an anhydride, that is, one obtained by chemically bonding maleic anhydride, etc., and has a Vikato softening point of 90°C or higher. Here, a resin obtained by acid-modifying an ethylene-vinyl acetate copolymer using a similar method has a Vikato softening point of less than 90°,
It cannot withstand use at high temperatures and is not practical. Examples of acid-modified olefin resins in the present invention include:
Examples include Mitsui Petrochemical's Admer. [Effects of the invention] According to the invention, in a conventional laminate having a structure in which polyvinylidene chloride is used as a barrier layer and ethylene-vinyl acetate copolymer is arranged on both sides, both outer layers are not easily formed during high heat treatment, such as boiling treatment. Although peeling and deformation of the laminate occurred, the laminate according to the present invention was able to withstand high-temperature treatment. In addition, conventional laminates with heat-resistant resin such as nylon on the outer layer can withstand high-temperature treatment, but the layer structure has four or more layers, which poses problems in terms of manufacturing and economic efficiency. According to the method, a heat-resistant and oil-resistant packaging material can be obtained by a simple method, and is suitable as a packaging material for meat, etc. Example 1 Using a coextrusion film forming apparatus equipped with two extruders,
A film was prepared by laminating vinylidene chloride resin A and acid-modified polypropylene B, which is obtained by acid-modifying polypropylene with maleic acid, in the order of B-A-B. The thickness of each layer is 40μ, 10μ, 40μ in the order of B-A-B.
The total amount was 90μ. Example 2 A film similar to that in Example 1 was produced using maleic acid-modified linear polyethylene instead of acid-modified polypropylene. Comparative Example 1 A film similar to that in Example 1 was made using ethylene-vinyl acetate copolymer instead of acid-modified polypropylene. Using Examples 1 and 2 and Comparative Example 1, bags were made by stacking two sheets and heat-sealing them. This bag is filled with beef tallow and sealed by heat sealing.
Processing conditions for 30 bags: 60℃, 30℃
Minutes: 70°C, 30 minutes: 80°C, 0 minutes. The results are shown in Table-1. 【table】

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the laminate of the present invention.

Claims (1)

[Scope of utility model registration request] In a laminate in which an acid-modified olefin resin layer or an olefin resin layer containing an acid-modified olefin resin is arranged on one or both sides of a vinylidene chloride-based resin layer, the acid-modified olefin resin is medium density polyethylene, high density polyethylene, linear chain A laminate made of acid-modified olefin resin, which is made by chemically bonding low-density polyethylene or polypropylene with an unsaturated resin acid or its anhydride, and has a Vikatsu softening point of 90°C or higher.