JPS62271721A - Manufacture of laminated - Google Patents

Abstract

PURPOSE:To obtain a laminated whose each resin can be stripped and trimmed product possesses expected characteristics such as adhesion, by a method wherein three kinds of coextruded resin are molded on both trimmed edges, to which trimming is applied and the remainder to which the trimming has been applied is made into a product. CONSTITUTION:A laminated having a resin (resin C) layer composed of polyolefin or its copolymer obtained by grafting acrylic acid or dibasic unsaturated carboxylic acid between resin (resin A) layer composed of ethylene-vinyl acetate copolymer and resin (resin B) layer composed of the polyolefin is manufactured. In this instance, the resin A, B layers between which the resin C layer has been interposed is extruded at the temperature of less than the die temperature of 220 deg.C. The resin A layer (or the resin B layer) and resin C layer are extruded at a time and at the temperature of less than the die temperature of 220 deg.C and the molten resin B layer (or the molten resin A layer) is piled up on the surface of the resin C layer at the temperature of less than 220 deg.C and linear pressure of less than 1kg/m. After removal of an edge part by cutting off the obtained laminate in desired width, the linear pressure of 2kg/m or more is applied to the laminated thing in the desired length under the temperature of 240 deg.C or more.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention provides a film or sheet-like laminate useful for bags, containers, etc. for food packaging, medical product packaging, etc. The present invention relates to a method for manufacturing a laminate that can efficiently produce a part of the laminate in a recoverable state.

[Prior art] Saponified ethylene-vinyl acetate copolymer (resin A) has low permeability to gases such as oxygen, nitrogen, and carbon dioxide. , vacuum packaging,
It is used in fields such as food, medical equipment, and pharmaceuticals that require antioxidant packaging.

On the other hand, resin A has drawbacks such as high moisture permeability, poor impact strength, and increased gas permeability due to moisture absorption.

In order to improve these drawbacks, resin A is being combined with a hydrophobic synthetic resin such as polyolefin (resin B).

In that case, the adhesion between the two is generally not good, so in order to improve the adhesion, a resin (resin C,) Intervening lamination of layers (
Japanese Patent Publication No. 53-36872) and modified ethylene-vinyl acetate copolymers graft-modified with acrylic acid or maleic anhydride (laminated with resin CD interposed (Japanese Patent Publication No. 58-35125) have been proposed. (Resins C1 and 02 are collectively referred to as resin C).

In this case, layer a of the adhesive layer consisting of a composite of resin B and resin C not only improves the adhesion of resin A to resin B, but also provides heat sealability and moisture resistance, and This feature prevents the gas permeability from increasing due to moisture absorption. However, in order to bring out these characteristics, a new problem arose due to the interposition of a contact M layer to improve interlayer adhesion.

That is, the laminate is often made by laminating molten resins A, B, and C, laminating molten resin C between films of resins A and B, or by multilayer coextrusion molding. This multilayer coextrusion molding is generally a method in which plastic molding materials melted and kneaded by a plurality of extruders are simultaneously fed into a coextrusion die in layers to obtain a multilayer laminate.

However, as with the other methods mentioned above, even in multilayer coextrusion, the edges of the laminate usually do not become a product due to irregularities in lamination, waving, wrinkles, etc. Slitting (trimming) is performed using a trimming device.

However, regarding the 1% portion of the laminated product with an intervening adhesive layer as described above, the adhesive layer and resin A layer or B layer
Since it is difficult to peel off the layer, resins A and B are used to collect and recycle both ends.

There is only a method of using C simultaneously, and the uses of these mixed resins are somewhat limited.

[Problem to be Solved by the Invention 1] The present invention provides a laminate in which resin A is used and resin C is used as an adhesive layer with resin B, and the laminate is trimmed with 14 layers left, and each resin is The object of the present invention is to provide a technique that allows A, B, and C to be peeled off and collected individually, and that the trimmed product can obtain a laminate having desired properties such as adhesiveness.

Other objects and novel features of the present invention will become apparent from the entire description.

[Means for Solving the Problems] and [Operation] To briefly describe the means and operation according to the present invention, in the present invention, as a first step, resins A and B are applied to the trimmed both ear portions.

The coextrusion is molded so that each layer of C has enough adhesive strength to be separated and separated, and then trimmed.The trimmed part is separated into each layer in a separate process, and each component is recycled. can do. In the second step, the trimmed residue is made into a product, but since it is extruded at a relatively low temperature, the adhesive strength is low.
When the coextrudate is subjected to heating and pressurizing operations, a laminate with high interlayer adhesive strength can be obtained.

In the conventional manufacturing method of the laminate, since the adhesion between resin A and resin B is poor, an adhesive layer of resin C is interposed, the laminate is melted and bonded at high temperature inside the goo, and the edges are trimmed after extrusion. ing. Therefore, the resin A is used for the ears.

B and C have been reused as needed without separating them.

Furthermore, it is virtually impossible to reuse thin materials such as films.

In this way, the method of the present invention increases the strength of the product by: 1. The selvage can be separated into resins and recycled.

Although the above method is a method of simultaneous coextrusion of each resin, the present invention is not limited to this method. That is, epsilon resin B is separately extruded from A and C, and resin A and resin B are extruded separately.

Similar effects can also be achieved by extruding C separately into a low adhesion state as described above and then combining with other layers.

In this case, the other layers should be considered for trimming the ears, collecting the first layer,
Avoid high temperature bonding.

That is, 1 the present invention has at least one layer of a resin (resin A) F made of a saponified product of an ethylene-vinegar vinyl copolymer, and at least one layer of a resin (resin B) made of a polyolefin. , when producing a laminate having a resin (resin C) layer made of a polyolefin or a copolymer thereof grafted with acrylic acid or dibasic unsaturated carboxylic acid between the resin A layer and the resin BM, the first step is to (1) Resin CR is interposed between the resin A layer and the resin B layer and pressed at the same time at a dance temperature of 220"C or less.
(2) Extrude the resin A layer (or resin B layer) and resin C layer simultaneously at a die temperature of 220"C or less, and
Molten resin BM outside the chair? (or molten resin A layer) to resin C
As a second step, the laminate obtained in (1) or (2) above is cut to the desired width, and the edges are removed. , the desired width of the laminate is 240'
The present invention relates to a method for manufacturing a laminate, characterized in that a linear pressure of 2 kg/m or more is applied at a temperature of C or more.

The saponified ethylene-vinyl acetate copolymer resin A used in the present invention contains a relatively small amount of ethylene, and is made by saponifying the acetate groups of the vinyl acetate component to form a vinyl alcohol component. The content, degree of saponification, etc. can be appropriately selected in consideration of gas barrier properties, etc.

For example, ethylene content is 50 mol% or less, saponification degree is 90
% or more of saponified ethylene-vinyl acetate copolymer is used.

The polyolefin of resin B used in the present invention is 1
For example, homopolymers such as polyethylene and polypropylene; ethylene, propylene, l-butene, -hexene,
Examples include copolymers such as nyoctene.

The polyolefin grafted with acrylic acid or dibasic unsaturated carboxylic acid or its copolymer as resin C constituting the adhesive layer of resin A and resin B used in the present invention is 1, for example, polyolefin or ethylene-vinyl acetate. Examples of saponified copolymers include acrylic acid or dibasic unsaturated carboxylic acid graft copolymers, and the saponified parts of polyolefins and ethylene-vinyl acetate copolymers include those similar to those exemplified above. Examples of dibasic unsaturated carboxylic acids include maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride.

In the present invention, as a first step, resin A, resin B,
The adhesive layer peels off and can be separated.

Molding the bonded coextrudate inside the goo below 220'C.

An example of the temperature is less than 240'Q, preferably less than 220°C. Also, resins A and C are extruded at low temperature, and resin B is extruded at high temperature.

The welding may be performed at a low temperature outside the gouer, or only the resin A may be joined to the resin C side of the resin B having the resin C outside the gouer.

The coextrudate, such as the film Φ sheet after trimming, is then subjected to post-treatment. That is, heating and pressurizing operations are performed.

The appropriate heating temperature is 240'C or higher.

The pressure during pressurization is preferably 2 kg/m or more as a linear pressure.

The structure of the laminate according to the present invention includes at least a resin A layer (hereinafter sometimes referred to as A layer), an adhesive layer made of resin C (hereinafter sometimes referred to as C layer), and resin B (hereinafter sometimes referred to as B layer). In addition to those with a three-layer structure consisting of (1), there are also those with four or more layers, and various resin layers such as polyamide and polyester may be further laminated by means such as lamination or coating. Examples of the structure of the laminate include B layer/C layer/A layer/C layer/
Examples include B layer, B layer/CE/A layer/CF3/polyamide, and the like. The laminate of the present invention can be used not only for films and sheets but also for a wide range of applications such as various containers.

[Example 1] Next, the present invention will be explained based on Examples and Comparative Examples.

Example 1 Saponified ethylene-vinyl acetate copolymer (ethylene content 38 mol%, saponification degree 99 mol%,
Melt index 12.0g/10 minutes (JISK 8
758) ) Polypropylene (density 0.900 g/a
m”, melt index io, og/10 minutes (JIS
K 87C layer component is polypropylene (density 0.90
0 g/cm”, melt index 20 g/10 min (JISK 6758)) graft copolymer of maleic anhydride (graft amount of maleic anhydride 0.8 mol%
), thickness of B layer/C layer/A layer/C layer/B layer = B layer 20 glC layer LoJL/A layer 20 gl/C layer IO pot/B
Layer 20, layer A, layer B, and layer 0 were coextruded at a temperature of 215 to 220° C. at the confluence of molten resins to obtain a sheet-like multilayer coextrudate.

Then, the ears of the coextrudate obtained above were trimmed. Layer A, layer B, and layer 0 were easily peeled off from the ear portion, and each resin was recovered.

Next, as a second step, this sheet-like material is heated to 240°C, passed through a heat treatment machine under a linear pressure of 2 kg/m,
Heat treatment was performed.

For this laminate, the adhesive strength between both layers A and C was measured using an autograph at a tensile speed of 300Φm/min and a temperature of 23°C.
3000g as measured by 180° peeling method.
/ Obtained a value of 15a+m or more.

Comparative Example 1 Saponified ethylene-vinyl acetate copolymer (ethylene content 38 mol%, saponification degree 98 mol%,
Melt index 12.0g/10min (JrSK 8
? 5fl)) Polypropylene (density 0.900g/c) as B layer component
rn”, melt index 10.0g/10min (JI
SKCM acid component is polypropylene (density 0.900g
/ cm”, melt index 20g/10 minutes (
JISK8758) Graft copolymer of maleic anhydride to ) IO, 8 mol%)
At 250 degrees C Co-extruded.

Regarding these laminates, the adhesive strength between both layers A and C was measured in the same manner as in Example 1, and the result was approximately 2900 g/
A value of 15 mm was obtained.

Furthermore, it was impossible to peel and separate the layers of the trimmed edges.

Example 2 Comparative Example 2 Each laminate obtained in Example 1 (Comparative Example 1) was treated under the following treatment conditions:
Changes in adhesive strength between A and C were measured under different standing conditions.

The results are shown in Table 1. It was found that the laminate obtained in Example 1 was excellent over time and also in high temperature treatment, high humidity treatment, and high temperature water treatment.

Table 1 Comparative Example 2 2900 2200 1100 580 3
10 (unit: g/15 mm) Comparative Example 3 The same conditions as in Example 1 were used except that 240°C in the second stage was changed to 220°C. The adhesive strength was 850 g/10 mm.Comparative Example 4 The same conditions as in Example 1 were used except that 2 kg/mm in the second stage was changed to 1 kg. Adhesive strength is lIoog/15m
It was m.

Comparative Example 5 In Example 1, 240°C was set to 220°C, and 2kg/I1
The adhesive strength was 550 g/15 mm under the same conditions except that 1+ was 1 kg/mm.

As is clear from the comparison of the above examples and comparative examples,
By performing multilayer coextrusion at 220° C. or lower, the saponified ethylene-vinyl acetate copolymer layer can be easily peeled off, and the selvedge trimming portion can be collected and recycled. By applying only the trimmed multilayer coextruded film or the ethylene-vinyl acetate copolymer saponified layer in the second step of heat-pressure adhesion, it has superior adhesion strength to the conventional multilayer coextrusion film that is immediately applied. I was able to get something. Since there is essentially no change in oxygen permeability, when used as food packaging or medical film or sheet containers, deterioration in quality, deterioration, and discoloration of the contents can be sufficiently prevented. Furthermore, since the interlayer adhesive strength is high, it can be effectively used to protect contents from external forces and prevent bag breakage.

[Effects of the Invention] According to the present invention, a laminate in which resin A is used and resin C is used as an adhesive layer with resin B is trimmed while these are laminated, and each resin A, B, We were able to provide a technique that allows C to be peeled off and recovered individually, and the trimmed product can obtain a laminate with desired properties such as adhesiveness.

Claims (1)

[Scope of Claims] It has at least one layer of resin (resin A) made of a saponified product of ethylene-vinyl acetate copolymer, and has at least one layer of resin (resin B) made of polyolefin, and
In producing a laminate having a resin (resin C) layer made of polyolefin or its copolymer grafted with acrylic acid or dibasic unsaturated carboxylic acid between the resin A layer and the resin B layer, the first step is to (1) Resin C layer is interposed between resin A layer and resin B layer and extruded at the same time at a die temperature of less than 220°C, or (2) Resin A layer (or resin B layer) and resin C layer. are simultaneously extruded at a die temperature of 220°C or less, and molten resin B layer (or molten resin A layer) is extruded on the surface of resin C layer at 220°C outside the die.
℃ or less and under a linear pressure of 1 kg/m or less.As a second step, the laminate obtained in (1) or (2) above is cut to a desired width, and after removing the edges, the laminate of the desired width is cut. A method for producing a laminate, which comprises applying a linear pressure of 2 kg/m or more to the laminate at a temperature of 240° C. or higher.