JPS59192564A - Gas barriering laminate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminate of a saponified polyolefin and ethylene-vinyl acetate copolymer, which has good gas barrier properties and excellent interlayer adhesion. More specifically, a polyolefin is laminated on one or both sides of a gas barrier material layer made of a saponified ethylene-vinyl acetate copolymer treated with a boron compound via an adhesive layer made of a modified polyolefin having a carboxyl group or a hydroxyl group. gas barrier
The present invention relates to a laminate.

It is well known that saponified ethylene-vinyl acetate copolymers have low oxygen permeability and extremely excellent gas barrier properties. On the other hand, polyolefins have excellent mechanical strength, moisture resistance, and heat sealability.
It is highly valued as a base material for packaging materials and containers.

It is desirable to use the packaging material 2 and container that take advantage of these mutual features in a laminate by combining them with each other, but for this purpose, the adhesiveness between each layer must be strong.

Therefore, an adhesive layer is required to bond the polyolefin and saponified ethylene-vinyl acetate. Those neutralized with salt, so-called ionomers, are used.

However, when forming a laminate, coextrusion is carried out at high speed, and if the adhesive layer is thin, the adhesive strength will be extremely reduced, causing a practical problem.

In view of these circumstances, the inventors conducted intensive studies to improve the adhesion between the polyurethane resin and the gas barrier material layer, and as a result, they treated the saponified ethylene-vinyl acetate copolymer with a boron compound. Gas bar 3 - A laminate with strong interlayer adhesion and excellent gas barrier properties can be obtained by fully laminating polyolefins via modified polyolefins having carboxyl or hydroxyl groups on one or both sides of the rear material layer. I discovered that.

The greatest feature of the present invention is that by combining a saponified ethylene-vinyl acetate copolymer treated with boron and a polyolefin modified with a carboxyl group or a hydroxyl group as a functional group, the boron compound and the functional It was discovered that excellent adhesiveness is developed due to interaction with the group.

Furthermore, since the interlayer adhesion between the polyolefin and the polyolefin modified with such a carboxyl group or hydroxyl group is excellent, the interlayer adhesion between each layer of the inventive laminate is extremely excellent.

Furthermore, by using polyolefin as a base material, it is possible to provide containers and packaging materials with good heat sealability and excellent mechanical strength. Furthermore, even if the adhesive layer is made thinner, the present invention provides a barrier between polyolefin and gas barrier.
It also has the excellent advantage that it is possible to obtain a laminate with excellent interlayer adhesion between the material layers.

The saponified ethylene-vinyl acetate before boron compound treatment, which is the gas barrier material of the present invention, has an ethylene content of 20 to 55%.
If the saponification degree is 90 molt or higher and the ethylene content is high, the amount of hydroxyl groups will decrease and a high degree of gas barrier property will not be obtained.If the ethylene content is less than 20 molt, the gas barrier property during moisture absorption will deteriorate. is reduced, and processability is also reduced. Therefore, the ethylene content is between 20 and 55
Although it is limited to mulch, the depth is 25 to 45 mulch. These saponified ethylene-vinyl acetate copolymers are produced by copolymerizing vinyl acetate under pressure with ethylene in the presence of a radical initiator using a solvent if necessary.
It can be obtained by obtaining a vinyl acetate copolymer, and then removing unreacted substances, solvent, etc. from this copolymer, and then saponifying the copolymer under normal saponification conditions, for example, in an alkali-methanol solution.

In the present invention, it is essential to treat the saponified ethylene-vinyl acetate copolymer with a boron compound, but the treatment with the boron compound may be performed immediately after saponification, or after saponification, This may be done after it has been sufficiently dried. In that case, the boron compound is preferably used after being dissolved in a solvent (for example, water). From the viewpoint of ease of treatment, it is preferable to perform a boron compound treatment before and after washing and subsequent acid treatment for thermal stabilization after saponification. The best boron compound to treat is boric acid, but Sono et al. also use trichlorboron, triphenylboron,
Also effective are trimethylboron, coordinations of these with ethers or amines, or monomers of boron through oxygen and nitrogen bonds. The amount of boron compound used is 0.002 to 0.2% by weight (20 to 2000%) as boron content based on the saponified ethylene-vinyl acetate copolymer.
ppm), preferably 0ζ005 to 0.1% by weight (50
-1000ppm) τ. If the boron content is too low, the adhesion with the adhesive made of modified polyolefin will not be sufficiently good, and if it is too high, the saponified ethylene-vinyl acetate copolymer will gel, resulting in poor moldability. Become. In addition, it is important to treat the H6-1 compound in a neutral or acidic environment. If you treat it in an alkaline environment, it will thermally stabilize the saponified ethylene-vinyl acetate copolymer instead of making it acidic. It's a waste of time to be there, and it's not good.

Polyolefins as base materials include ethylene, propylene,
The polymer may be a single or copolymer of 1-butene, -heptane, 1-hexene, etc., and low-density polyethylene, medium-density polyethylene, high-density polyethylene, isotactic polypropylene, etc. are particularly preferably used.

Examples of modified polyolefins treated with a boron compound and having carboxyl or hydroxyl groups that form a strong adhesive layer between the saponified ethylene-vinyl acetate and the base polyolefin include carboxylic acid-modified polyolefins and carboxylic acid-modified ethylene-vinyl acetate.゛Q acid vinyl copolymer, carboxylic acid modified ethylene-acrylic acid ester copolymer,
Examples include partially or completely saponified ethylene-vinyl acetate copolymers having an ethylene content of 70 to 99 mol. Carboxylic acid 7-Fl Polyolefins include olefin monomers such as ethylene, propylene, isobutylene, and 1-hexene, and ethylenically unsaturated compounds having carboxyl groups 1, such as acrylic acid, methacrylic acid, maleic anhydride, maleic acid, and crotonic acid. , itaconic acid, etc., or copolymers of it with metal ions (e.g., Na+, K+, Ca2+, Mg2
+, zn2+) te neutralized ionomers, and also those obtained by graft copolymerizing polyolefins with ethylenically unsaturated compounds having carboxyl groups. Carboxylic acid-modified ethylene-vinyl acetate copolymers include those copolymerized with an ethylenically unsaturated compound having a carboxyl group, as well as those copolymerized with an ethylenically unsaturated compound having a carboxyl group, as well as those obtained by graft polymerization, as in the case of the above polyolefin, and the content of vinyl acetate is the total amount. However, it is preferably 0.1 to 157%. In addition, the carboxylic acid-modified ethylene-acrylic acid copolymer is a copolymer of ethylene, an acrylic ester, and an ethylenically unsaturated compound containing a carboxyl group, or a copolymer of ethylene-acrylic ester with a carboxy-8-cyl group added. This includes graft polymerization of ethylenically unsaturated compounds having the following properties. Examples of acrylic esters include methyl (meth)acrylate, neil (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and the content of these acrylic esters is It is preferable that the amount is 0.1 to 457% based on the total amount.

In addition, a partially or completely saponified ethylene-vinyl acetate copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer having an ethylene content of 70 to 99 moles and a vinyl acetate content of 1.0 to 30 moles to remove 10 to 20 moles of hydroxyl groups. It contains. In addition, the partial or completely saponified ethylene-vinyl acetate copolymer also includes those obtained by copolymerizing or graft-polymerizing an ethylenically unsaturated compound having a carboxyl group to the ethylene-vinyl acetate copolymer and saponifying this. It will be done.

The carboxyl group content of the above-mentioned modified polyolefin having a carboxyl group is 0.1 in terms of C00Hi standard amount.
to 5.0 weight, preferably 0.3 to 3.0 weight. If the amount of carboxyl groups is small, adhesiveness will not be exhibited, and if it is more than 5.0% by weight, it will be difficult to form a laminate, which is not preferable. Further, the content of hydroxyl groups in the modified polyolefin having hydroxyl groups, particularly in the saponified ethylene-vinyl acetate copolymer, is 1.0 to 20 moles, preferably 2 to 10 moles. If the amount of hydroxyl groups is small, the adhesion to the gas barrier material layer will be reduced, and if it exceeds 20 molt, the adhesion to the polyolefin will be impaired.

The most advantageous method for producing the gas barrier laminate of the present invention is to use a modified polyolefin having a carboxyl group or a hydroxyl group on one or both sides of a saponified ethylene-vinyl acetate copolymer treated with a boron compound. An example of this method is melt coextrusion. As the melt molding method, any method such as T-die extrusion method, inflation extrusion method, blow molding method, etc. can be implemented. In the melt coextrusion T-die method, it is effective to wind up the laminate at a winding speed of 3 m/see or higher.

Strong interlayer adhesion even when wound at speeds of 3 m/min or more
Obtaining a low temperature improves productivity, which is of great industrial significance.

Although there is no particular restriction on the thickness of each layer of the laminate thus obtained, it is effective for the adhesive layer to have a thickness of 2 to 100 microns, preferably 2 to 40 microns.

The uninvented laminate has a basic structure of three layers of polyolefin/adhesive/gas barrier material or five layers of polyolefin/adhesive/casbarrier material/adhesive/polyolefin, but this basic structure can be modified as needed. It is free to laminate other resin layers.

The shape of the uninvented laminate is, for example, a container such as a box, bottle, or plate.
7)% films, bags or tubes made by heat-sealing these films, etc.

Furthermore, since the inventive laminate has excellent gas barrier properties, it is suitably used in fields where gas barrier performance is required, particularly in the field of food packaging.

Next, the material of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Vinyl acetate 20002 was placed in an autoclave with an internal volume of 5 tons.
After charging methanol 2501 and replacing the air with ethylene gas or ethylene gas, the ethylene pressure was set to 40 odor/- (gauge pressure), and 2,2'-azobisisobutyronitrile was added at 60°C. After polymerization for a period of time, an inhibitor was added and unreacted substances were removed. The produced ethylene-vinyl acetate copolymer was saponified in a sodium hydroxide-methanol solution to obtain a saponified ethylene-vinyl acetate copolymer having an ethylene content of 32 mol and a saponification degree of 99.6 mol. This saponified substance 50? was dispersed in 3.5L of water, 0.35F of boric acid was added thereto, and after stirring at room temperature for 4 hours, the liquid was removed using a centrifuge, and then heated at 70℃ for 5 hours and then at 105℃.
It was dried for 16 hours. When the amount of boron in this resin was measured using atomic absorption spectrometry, the amount of boron was found to be iso ppm.
Met. Melt index (MI) of the saponified ethylene-vinyl acetate copolymer treated with boric acid
) in accordance with ASTM-D-1238-52T using a melt indexer at a temperature of 190°C and a load of 216 (liters).
When measured at the same time, it was 0.82 f710 minutes.

Next, this E'71M-treated gas barrier material (A) and the ethylene-amino acid dinylphate copolymer grafted with anhydrous maleic acid/carboxylic acid]! t1.1 weight, vinyl acetate component 6 molφ, MI=1.4r/lυ min) adhesion I(
B) υ and density* 0.918, MI=2. OS'/'1
Prepare low-density polyethylene (C) of 0 min. and obtain a laminate using the following method. The extruder (1) is equipped with an extruder (III) and uses a flat die type three-type five-layer coextrusion device Sl!, which is extruded by sequentially passing (■), (+llJ), and the extruder (1) is equipped with a gas barrier material. (A) into an extruder (
The additive material (B) was supplied to II), and the polyethylene base material (C) was supplied to the extruder (III), and coextrusion was performed at a die temperature of 210°C and a take-up speed of 5 m/min. /(B)/
A laminate of five layers of three types (A)/(B)/(C) was obtained. The thickness of each layer is (A) layer 30μ, (B) layer 15μ, (C
)191 was 100μ. This five-layer (A)/(B
) was measured at 90°13-peel and found to be 0.79 Kp/shoulder. The adhesive force between (B) and (C) is strong, and the bond between (B) and (C) is strong.
It was impossible to peel it off.

Examples 2 to 12 A saponified ethylene-vinyl acetate copolymer was prepared in the same manner as in Example 1, and treated with lsl boric acid as shown in Table 1. B) Also, various polyolefin base materials (C) were used and coextruded using the same extrusion equipment as in Example 1, resulting in (C)/(B)/(A)/(B)
A laminate of three types and five layers of /(C) was made.

When the adhesion between (A) and (H) was evaluated,
Table 1 shows excellent values.

Example 13 A saponified ethylene-vinyl acetate copolymer with an ethylene content of 44 molt and saponification [99.5%] was prepared and treated with boric acid to give a boron content of 220 ppm% Mll, 5f/1
A gas barrier material (A) of 0 minutes was obtained. Next, as an adhesive layer, low-density polyethylene grafted with maleic anhydride (
Using low-density polyethylene as a polyolefin base material containing coon (containing -xo, 3N amount %), a laminate of five layers of three types was obtained in the same manner as in Example 1 below. Part 4 is shown in Vermilion and Cloth L.

Example [4] In Example 2, 1 liter of ethylene-containing 32 mol of ethylene-vinyl acetate copolymer was substituted for the saponified ethylene-vinyl acetate copolymer.
A laminate was obtained under the same conditions as in Example 2 except that a saponified enalene-vinyl acetate copolymer having an i11'38 molar ratio was used. The results are shown in Table 1.

Comparative Example 1 Ethylene content used in Example 1: 32 mole, saponification degree: 9
9.6 mol of saponified ethylene-vinyl acetate copolymer was used as the gas barrier material layer (A) without boric acid treatment, and coextrusion was carried out in the same manner as in Example 1. A laminate was obtained. The thickness of each layer is (A) = 301t1 (B
)=15tls (C)=1. O (A
The peel strength between ) and (B) was 0.44 Ky/1wr, which was insufficient for practical use.

Comparative Example 2 In Comparative Example 1, low density polyethylene (COOH-containing OH
A laminate was obtained by coextrusion in the same manner as in Comparative Example 1, except that the coextrusion was carried out in the same manner as in Comparative Example 1.

Below margin

Claims (1)

[Claims] (1) Treated with a boron compound, having an ethylene content of 20 to 5
A gas barrier material layer made of a saponified ethylene-vinyl acetate copolymer with a saponification degree of 5 molty or more and a saponification degree of 90 molty or more is laminated with a polyolefin on one or both sides of the layer via an adhesive layer made of a modified polyolefin having a carboxyl group or a hydroxyl group. A gas barrier laminate. (2) The boron content of the saponified ethylene-vinyl acetate copolymer treated with a boron compound is 0.0 with respect to the saponified product.
The gas barrier laminate according to claim 1, wherein the content is 0.02% to 0.2% by weight. (8) The modified polyolefin having a carboxyl group or a hydroxyl group is a carboxylic acid-modified polyolefin, a carboxylic acid-modified ethylene-vinyl acetate copolymer, a carboxylic acid-modified ethylene-acrylic ester copolymer, or an ethylene content of 70 to 99 moles. The gas barrier according to claims 1 and 2, which is a partially or completely saponified product of an ethylene-vinyl acetate copolymer.
Sex laminate. (4) A gas barrier laminate according to any one of claims 1 to 3, wherein a gas barrier material and a polyolefin are laminated by coextrusion via an adhesive.