JPH02248249A - Multilayer plastic sheet having gas barrier properties - Google Patents

Abstract

PURPOSE:To obtain the title sheet being transparent, having high gas barrier properties and excellent in secondary processability by providing an adhesive layer composed of modified polyolefin between a sheath layer composed of polyethylene terephthalate and a core layer composed of polyamide having a xylirene group. CONSTITUTION:As a sheath layer, polyethylene terephthalate or thermoplastic polyester having 80mol.% or more of a polyethylene terephthalate unit is used and, as a core layer, polyamide having a xylirene group consisting of 70mol.% or more of m-xylirenediamine or p-xylirenediamine and 70mol.% or more of 6-12C alpha,omega-aliphatic dicarboxylic acid or a polyamide mixture containing 65wt.% or more of said polyamide is used. An adhesive layer composed of modified polyolefin is provided between these two layers to obtain the title sheet excellent in secondary processability. The thicknesses of the sheath, core and adhesive layers are respectively 70-98%, 1-15% and 1-15% based on the total thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a transparent multilayer plastic sheet that has excellent gas barrier properties and secondary additivity properties necessary for packaging materials.

(Prior Art) Linear polyester in general, and polyethylene terephthalate (hereinafter referred to as PET) in particular, has attracted attention as a material for various containers including bottles due to its excellent mechanical and chemical properties. Deep-drawn containers made from PIET sheets, as typified by the method described in Japanese Patent No. 5107, are also in increasing demand as containers with excellent rigidity and gas barrier properties.

However, as packaging technology advances and packaging applications expand, PIET containers are required to have even higher levels of functionality, especially when considering alternative uses for metal cans and glass containers. Although it has many advantages such as weight reduction, transparency, and safety, its lack of performance in terms of gas barrier properties and heat resistance is a bottleneck, and its use is limited.
Development is severely restricted.

On the other hand, as a sheet with good gas barrier properties, polyamide (hereinafter referred to as polyamide A sheet made from material (referred to as X) has also been proposed, but this sheet has impact resistance.

It has the disadvantage of poor pinhole resistance and water resistance.

(Problem to be solved by the invention) As a means for improving the gas barrier properties of 1'FT, I'
The aim is to provide a transparent multilayer plastic sheet with high gas barrier properties and good secondary processability by combining polyamide X, a material with even better gas barrier properties than ET, and PET. It is.

(Means for Solving the Problems) The present inventors have conducted intensive research for this purpose, and as a result, they have invented the following multilayer plastic sheet.

That is, the present invention provides a sheath layer made of polyethylene terephthalate or a thermoplastic polyester having 80 mol% or more of ethylene terephthalate units, and a diamine component in which 70 mol% or more of 1- is m-xylylene diamine or p-
-xylylenediamine, with 70% of the dicarboxylic acid component
A polyamide having a xylylene group in which mol % or more [.] is an α, ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms, or a polyamide 2 containing 65% by weight or more of the polyamide
[A sheath layer having a core layer made of a 16 compound and an adhesive layer made of a modified polyolefin between the sheath layer and the core layer.

1v of each of the core layer and adhesive layer is 7 of the total thickness.
The gist of the invention is a multilayer plastic sheet with gas barrier properties characterized by a gas barrier content of 0 to 98%, 1 to 15%, and 1 to 15%.

What is the thermoplastic polyester used in the present invention?

A product obtained by melt polymerizing a low polymer obtained by a conventional esterification reaction or transesterification reaction of terephthalic acid or a lower alkyl ester of terephthalic acid and ethylene glycol, or a solid-phase polymer. It is polymerized. The thermoplastic polyester having at least 80 mol% or more of ethylene terephthalate units also means polyethylene terephthalate or a copolymer consisting of 80 mol% or more of ethylene terephthalate units and other repeating units, that is, other copolymer components. However, as the other copolymerization components mentioned above, various acid components and glycol components can be used.

For example, acid components include phthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, 1hexahydroterephthalic acid, 2゜6-naphthalenedicarboxylic acid, 2,5-dibromoterephthalic acid, diphenyldicarboxylic acid. , trimellitic acid, trimesic acid, pyromellitic acid, etc., and glycol components include propylene glycol, diethylene glycol, tetramethylene glycol, polyethylene glycol polytetramethylene glycol, 1,6-hexJJ-7 diol, and trimethylene glycol. Examples include methylene glycol, neopentyl glycol, p-xylylene glycol, 1,4 cyclohexane dimetatool, and the like.

The molecular weight of thermoplastic polyester is approximately 10,000 to 10
A range of 0,000 is preferable from the viewpoint of physical properties and extrusion processability.

The core layer contains polyamide X or polyamide X at 65% by weight.
It consists of other polyamide mixtures containing the above. All of the diamine components of polyamide X are m- (or p-)
It does not need to be xylylene diamine, and it must be 70 mol% or more.
The diamine may be any one of these diamines or a mixture thereof.

1- Since the polyamides used as raw materials for the multilayer sheet of the present invention as described above are already well-known, detailed explanations of their manufacturing methods will be omitted.1 Specific examples of those particularly preferred in the present invention are shown below. .

Polyamide X includes poly(m-xylylene adipamide) and poly(m-xylylene adipamide).

Examples include poly(m-xylylene adipamide), poly(m-xylylene group p-xylylene adipamide), poly(m-xylylene/p-xylylene upper bacamide), and the like.

Examples of other blended polyamides include nylon 6, nylon 66, nylon 610. Nylon 10. Examples include nylon 12 and the like. It is desirable that these raw material polyamides have a relative viscosity of 1.5 to 3.5. It is preferred to use only polyamide

The modified polyolefin which is a component of the adhesive layer of the present invention is ethylene-modified with maleic anhydride graft.
Examples include vinyl acetate copolymers, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, and polypropylene modified with maleic anhydride grafts, and compositions containing these as main components.

By having 80 mol% or more of ethylene terephthalate units, the above-mentioned PET can exhibit many advantages such as mechanical properties as PET. If the thickness ratio of polyamide preferable. The modified polyolefin used for the adhesive layer should have a thickness of 1L to 1L because if the thickness ratio of the modified polyolefin to the entire multilayer seal is less than 1%, the adhesive force will not be sufficient and from the viewpoint of price.
It is desirable that it be 15%.

In addition, optional additives such as pigments, stabilizers, antistatic agents, lubricants, and a small amount of organic polymers can be added to the raw material resin of each layer as required.

A multilayer structure can be obtained by extruding the mixture as a basic unit through a multilayer die using three extruders dedicated to each resin.

(Function) In the present invention, PET and polyamide
It provides many of the advantages of T and the gas barrier properties of polyamide X.

In addition, each of the constituent components of such a multilayer sheet is selected from materials that are excellent in secondary processability such as deep drawing, and therefore can be formed extremely easily.

(Example) Example 1 Intrinsic viscosity 1.0 (7) 1 at PIET and load 2160g
There were 10 sheets at 90°C, and each layer was so firmly adhered that it could not be peeled off. The extrusion molding conditions for obtaining this sheet are shown in Section 1. The results are shown in Table 2.

MI41'j measured by the method shown in Table 1 was prepared with 3.5 g of maleic anhydride graft-modified ethylene-vinyl acetate copolymer, and these materials were thoroughly dried in a dedicated extruder. Extrude from multilayer goo using 3 machines.

PET (450μ)/Maleic anhydride graft modified ethylene-vinyl acetate copolymer (25μ)/Poly(m-xylylene adipamide) (50μ)/Maleic anhydride graft modified ethylene-vinyl acetate copolymer (25// ) /P
A sheet with a thickness of 1000// of 5 layers of UT (450μ) was obtained. Example 2: Transparent with no thickness unevenness between each layer. Comparative Examples 1 to 4 The method of Example 1
, I+ composition, thickness, and adhesive layer thickness were varied to obtain the results shown in Table 2.

It has excellent surface and secondary processability and can be widely used in food packaging containers and the like.

As can be seen from the above results, the examples according to the present invention have a gas barrier property of less than 0.2 cc/24 hr-% atm and good adhesion.

(Effects of the Invention) The multilayer plastic sheet according to the present invention takes advantage of the many advantages of PETO and has high gas barrier properties.
Mr. E 1: (Voluntary) 1. Indication of the case Japanese Patent Application No. 1-70970 2. Name of the invention: Gas barrier multilayer plastic seams]・3. Relationship with the case of the person making the amendment 1. Address for patent: Hyogo 1-50-5 Higashihonmachi, Amagasaki City, Prefecture Contents of amendment (1) In the last line of the fifth summer of the specification, “1.4-Cyclohexane dimetatool, etc. may be mentioned.” was changed to “1.4-
Examples include cyclohexane dimetatool, bisphenol A, and the like.

I am corrected.

” 541 Address 4-1-3 Kutabe-cho, Chuo-ku, Osaka Name
Unitika Co., Ltd. Patent Department Phone: 06-281-5258 (Dial-in) 4
, subject to correction

Claims (1)

[Claims] (1) A sheath layer made of polyethylene terephthalate or a thermoplastic polyester having 80 mol% or more of ethylene terephthalate units, 70 mol% or more of the diamine component being m-xylylene diamine or p-xylylene diamine, and a dicarboxylic acid component. A polyamide having a xylylene group in which 70 mol% or more of the polyamide is an α,ω-aliphatic dicarboxylic acid having 6 to 12 carbon atoms, or
It has a core layer made of a polyamide mixture containing 5% by weight or more, and an adhesive layer made of modified polyolefin between the sheath layer and the core layer, and the thickness of each of the sheath layer, core layer and adhesive layer is the total thickness. 70-98%, 1-15%
and 1 to 15% gas barrier multilayer plastic sheet.