JPS5846214B2 - Resin composition with excellent adhesive properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ethylene-vinyl acetate copolymer (hereinafter referred to as EVA
) and a water-soluble polymer.

The purpose is to have excellent adhesion and to use EVA
The object of the present invention is to obtain a resin composition having unique performance that takes into account the original properties of melt fluidity and moldability, as well as the water absorption and conductivity properties of a water-soluble polymer.

Specifically, the present invention provides a resin composition useful for extrusion coating resins, films, adhesives, and lamination adhesives.

Furthermore, we have developed a resin composition that has excellent melt adhesion performance for metals such as iron and aluminum, as well as materials with a normal surface such as polyolefin, polyvinyl chloride, ABS resin, and cellophane, which are conventionally difficult to bond. It is about providing.

Conventionally, various means have been used to obtain resins or resin compositions having adhesive properties related to EVA.

For example, there is a method of chemically modifying EVA itself.

In this method, EvA is graft-polymerized with α,β unsaturated carboxylic acid or its anhydride to introduce a carboxyl group to improve adhesiveness.

However, this method involves a step of graft polymerization.

Therefore, when graft polymerization is carried out by solution polymerization, technical operational difficulties such as removal of the solution after completion of polymerization are serious.

On the other hand, there is a method of mixing or kneading EVA with other thermoplastic resins to form a resin composition.

This method requires simple equipment and the mixing and kneading operations are easier than the polymerization operations.

Therefore, attempts have been made to produce an EVA-based resin composition with adhesive properties using these methods.

However, one with sufficient adhesive properties has not been obtained.

As a result of research, the inventors of the present invention found that a homogeneous mixture of EVA and a water-soluble polymer resulted in a resin composition having wet adhesive properties.

The present invention will be described in detail.

EVA and a water-soluble polymer are mixed and/or kneaded in the presence of an organic peroxide to form a homogeneous resin, %fl acid.

As a mixture for mixing and kneading, EvA is dissolved in one good solvent such as toluene or n-hexane, and then dispersed in an aqueous solution of a water-soluble polymer.

At that time, it is advisable to add a dispersant.

Thereafter, the solvent and water are removed to obtain a uniformly mixed resin composition.

In addition, EVA is dissolved in a solvent that is a good solvent for EVA and has good compatibility with water, and the dissolved solvent and an aqueous solution of a water-soluble polymer are mixed to form a uniform solution.

Then stir thoroughly. Thereafter, by removing the parts outside the solution, a uniformly mixed resin composition is obtained.The solvent may be tetrahydrofuran, acetone, or the like.

Furthermore, as another method, EVA and a water-soluble polymer are kneaded in the presence of an organic peroxide using a mixing device such as a roll or a kneader.

When carried out in a heated state in a method using a solvent, EVA
l? :, becomes easier to dissolve.

However, since an organic peroxide is present, a preferable temperature may be set in relation to the decomposition temperature of the organic peroxide.

Dissolving EVA in a solvent and mixing the solvent in which EVA is dissolved with an aqueous solution of a water-soluble polymer are preferably carried out using an apparatus having a forced stirring mechanism.

In the case of a method of kneading using a mixing device such as a roll or a kneader, the kneading temperature is determined in relation to the melting point of EVA, the decomposition temperature of EVA, and the melting point of the water-soluble polymer.

Further, when a water-soluble polymer is used as an aqueous solution, it is preferable to keep the kneading temperature relatively high in order to prevent the kneading temperature from dropping rapidly due to moisture.

Specifically, a temperature of 120°C or higher is sufficient.

Further, the kneading time may be selected so as to provide a uniformly mixed resin composition.

However, when a water-soluble polymer is used as an aqueous solution, water is removed during kneading, which requires mixing for a longer time.

Specifically, 5-minute packets or more are preferable.

In addition, the ethylene-vinyl acetate copolymer used in the present invention 1) may be produced by any method such as a high-pressure polymerization method under 1000 to 3000 atm, or a solution or emulsion polymerization method under 100 to 400 atm. may be used, vinyl acetate content 1 to 50M φ, melt index 0.1
~500j? /10m1n is preferable.

The reason why the vinyl acetate content is preferably within this range is related to the physical properties of the resin composition that affect the chemical properties such as compatibility with the water-soluble polymer and the adhesiveness of the resin composition.

In addition, the water-soluble polymer is a water-soluble vinyl whose main component is a repeating unit represented by the formula (wherein X is a hydrogen atom or an alkyl group, and Y is COOM (wherein M is a hydrogen atom or an alkali metal)). It is a polymer.

An example thereof is polyacrylic acid.

The organic peroxide has the formula R1-0-0-R''.

(In the formula, R1, R2, R3, R4, R5, and R6 represent hydrogen, an alkyl group, or a phenyl group.) A peroxide represented by the following formula can be used.

Examples include benzoyl peroxide, dicumyl peroxide, ditertiary butyl peroxide, cumene hydroperoxide, and the like.

If an organic peroxide is not used, the compatibility and dispersibility of EVA and the water-soluble polymer will be poor, and uniform dispersion will not be possible, and the composition will have a synergistic effect and remarkable improvement in adhesive properties. I can't do it.

The quantitative proportions of EVA, water-soluble polymer, and organic peroxide are determined by comprehensively considering the melt viscosity, processability, mechanical strength, and other factors in relation to the specific use of the resin composition. It can be decided.

Specifically, the water-soluble polymer has an EvA of 1 to 50
It's heavy and heavy.

This is because within this range, a resin composition with improved adhesiveness can be obtained and has physical properties and properties that can be used in extrusion coating resins, films, and adhesives.

The amount of organic peroxide may be used in an appropriate amount, but specifically, it is preferably in the range of 0.005 to 5.0 weight, more preferably 0.005 to 2.0 weight, based on EVA. good.

The type and amount of the organic peroxide are selected depending on the type of EVA, the type of water-soluble polymer, the quantitative ratio of both, and the method of mixing and crosstalk.

This is because if the amount of organic peroxide is increased, the resin composition may become harder than necessary and may become brittle.

It is also possible to use a similar combination of two or more types of EVA and two types of water-soluble polymers.

As for the water-soluble polymers, combinations of different ones are also possible.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited in any way.

Example 1 The following formulation was kneaded using a 4-inch roll.

Ethylene-vinyl acetate copolymer (vinyl acetate content: 2ON, melt index: 20P/10ml, Vicat softening temperature: 57°C) 25% aqueous solution of 601 polyacrylic acid 24f dicumyl peroxide 0.0!1M' ethylene-acetic acid After melting the vinyl copolymer, an aqueous solution of polyacrylic acid and dicumyl peroxide was added and kneaded at 170°C for 10 minutes.

The resulting composition had a tart index of 7.77P/1
It was 0m1n.

Sandwich this polymer between two aluminum plates and
Thermocompression bonding was carried out under the conditions of 50° C. and 110 Cl/−.

The kl/klT peel strength at this time was IO,okg/25.

In addition, A, 5/ of the ethylene-vinyl acetate copolymer used
A7T peel strength was between 2.5ky/25.

Upper east traffic example 1 The same procedure as in Example 1 was carried out except that the organic peroxide was not used.

The resulting polymer had poor compatibility, was opaque, and had a melt index of 15.0? 710m1n, At/A
The tT peel strength was 3.4 k, 9/25.

Comparative Example 2 The same procedure as in Example 1 was carried out except that polyacrylic acid was not used.

The obtained polymer has a melt index of 4.5? /
At/AtT peel strength 4.5 kg with l Omin
/25 It was Tomo.

Example 2 The same procedure as Example 1 was carried out except that the amount of polyacrylic acid was changed to 40r, and as a result, the melt index was 7, 49 f/
l Omin, AA/A/, T peel strength 12.4
The weight was 725 mm.

Example 3 Except for replacing polyacrylic acid with sodium polyacrylate,
The same procedure as in Example 1 was carried out.

The obtained polymer has a melt index of 6.8? /
l Omin, A.I.

/A, tT peel strength was 7.0 kg725 plates.

Example 4 The following formulation was blended using a 500 ml separable flask equipped with a stirrer.

Ethylene-vinyl acetate copolymer (Vinyl acetate content 32%, melt Index 30? / l Omin.

Vicat Softening point 40℃) 541 Polyacrylic acid (25φ aqueous solution) 24 Gubenzoyl peroxide 0.05P Tetrahydrofuran
3222 The above components were charged in one separable flask and then dissolved at 60°C for 2 hours.

The obtained solution was applied to one At plate with a thickness of 50μ, and
Thermocompression bonding was carried out at 0° C. for 5IQ/C71121 seconds.

Ah'AtT peel strength at this time is 27CH'715mm
Met.

Comparative example 3 The same procedure as in Example 4 was carried out except for the following conditions.

Ethylene-vinyl acetate copolymer 60F Tetrahydrofuran 3401 A of the resulting solution Ukt
The T peel strength was 1201/15.

Claims (1)

[Claims] 1 Ethylene-vinyl acetate copolymer with 1 to 50 weight φ weight formula (wherein X is a hydrogen atom or an alkyl group, and Y is COO
A water-soluble vinyl polymer mainly composed of repeating units represented by M (in the formula, M is a hydrogen atom or an alkali metal)
．． A resin composition with excellent adhesive properties obtained by mixing in the presence of an organic peroxide having a weight of 005 to 5.0 weight φ. 2 The vinyl acetate content of the ethylene-vinyl acetate copolymer is 1 to 50% by weight, and the melt index is 0.1 to 500.
The resin composition according to claim 1, which has a P/l of 0 m1n.