JPS5846215B2 - Resin composition with excellent adhesive properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ethylene-vinyl acetate copolymer (hereinafter referred to as BVA) composition having excellent adhesive properties.

More specifically, it relates to a resin composition consisting of EVA and polyvinyl alcohol, and its purpose is to create a resin that has excellent adhesive properties, as well as excellent melt flowability and moldability, which are the inherent characteristics of EVA. The purpose is to obtain a composition.

Specifically, the objective is to provide a resin composition useful for extrusion coating resins, films, adhesives, lamination adhesives, and the like.

Furthermore, it is an object of the present invention to provide a resin composition that has excellent melt adhesion performance even for metals such as iron and aluminum, and materials with smooth surfaces such as polyolefin, polyvinyl chloride, ABSat resin, cellophane, etc., which are difficult to adhere to conventionally. It is in.

Although EVA is widely used in hot melt adhesives, coating agents, etc., its adhesive strength may not be sufficient depending on the purpose, and various improvements have been attempted.

For example, a method is known in which EVA is graft-polymerized with α,β-unsaturated carboxylic acid or its acid anhydride to introduce carboxyl groups to improve adhesiveness.

However, this method requires a reaction device for graft polymerization, a device for removing the solvent after completion of polymerization, etc., which inevitably leads to a significant increase in cost, and is accompanied by operational difficulties, resulting in many problems.

Also known is a method of mixing or kneading BVA with other thermoplastic resins to prepare a resin composition.

This method requires simple equipment and is easy to operate.

Therefore, various attempts have been made to obtain EVA-based resin compositions with excellent adhesive properties using this method.

However, the adhesiveness of the resulting composition was only slightly improved, and a sufficient level of adhesion has not yet been obtained.

Therefore, as a result of intensive research in order to obtain a resin composition with excellent adhesive properties, the inventor of the present application has developed a uniform and excellent adhesive resin composition by heating and mixing EVA and polyvinyl alcohol in the presence of an organic peroxide. The present invention was achieved by discovering that the following can be obtained.

Attempts to make a hot melt adhesive by mixing EVA and polyvinyl alcohol are already known (for example, JP-A-51-96832).

However, this technology is an aqueous solution hot-melt adhesive for bookbinding, paper carton, etc., and is a technology for improving the properties of polyvinyl alcohol, which is mainly composed of polyvinyl alcohol with a low molecular weight and low degree of saponification.

With this method, excellent adhesion to metals, resins, etc. cannot be expected.

There is no known technique for mixing polyvinyl alcohol with a high degree of polymerization and a high degree of saponification used in the present invention with EVA.

The main reason for this seems to be that EVA and polyvinyl alcohol are not uniformly miscible with each other.

The inventors of this application have discovered the surprising fact that compatibility and adhesiveness are greatly improved by mixing in the presence of an organic peroxide.

This phenomenon is extremely unique, and although the mechanism of action of organic peroxides is not clear, it is thought to be roughly as follows.

(1) Polyvinyl alcohol is grafted onto EVA, improving compatibility.

(2) EVA and polyvinyl alcohol are crosslinked in a complicated state, forming a so-called IPN (interpenetrating network) and being compatible.

(3) Compatibility is improved by the presence of a decomposition product of the organic peroxide or an unknown substance secondary to the organic peroxide.

It is presumed that polyvinyl alcohol is uniformly dispersed due to the above reasons or other difficult to predict reasons, and as a result, high adhesive strength is exhibited.

The mixing method for producing the composition of the present invention is to mix BVA and polyvinyl alcohol with organic peroxide using a conventional mixing device such as a hot roll, kneader, Bamba IJ-1-screw or twin-screw extruder. A method of kneading in the presence of the compound can be adopted.

The crosstalk temperature may be selected within the range of above the melting temperature of EVA and below the lower of the decomposition temperature of BVA or polyvinyl alcohol, specifically 100°C or above and 200°C.
The following are desirable.

The mixing time is determined by the decomposition of organic peroxide at the mixing temperature,
It is desirable that the remaining amount lasts a negligible amount of time or longer.

If the time is shorter than this, the compatibility of polyvinyl alcohol will not be sufficient, and the adhesive force will not be sufficiently exerted.

Furthermore, problems such as emitting a strange odor occur during adhesion.

When polyvinyl alcohol is used as an aqueous solution, it is necessary to prevent the kneading temperature from dropping rapidly due to evaporation of water, and equipment with a large heat capacity is desirable.

In the case of an extruder, the best model is one with a vent to remove water vapor.

Alternatively, a method using a solvent can also be adopted.

For example, EVA is dissolved in a solvent that is a good solvent for EVA and has good compatibility with water, and an aqueous polyvinyl alcohol solution and an organic peroxide are mixed therein to form a uniform solution.

After heating and stirring for a period of time at which the organic peroxide is substantially no longer present, the solvent is removed to obtain a uniform resin composition.

Note that tetrahydrofuran, acetone, etc. can be used as the solvent.

The EVA used in the present invention is 1000 to 3000
It may be manufactured by any method such as high-pressure polymerization under atmospheric pressure, or solution or emulsion polymerization under 100 to 400 atmospheres, and has a vinyl acetate content of 1 to 60% by weight and a tart index of 0.1 to 5005. '/10 minutes is preferable.

The reason why it is preferable to have a vinyl acetate content in this range is as follows.
This is due to the excellent compatibility with polyvinyl alcohol and the excellent adhesive strength of the resulting composition.

Moreover, the polyvinyl alcohol used in the present invention is
Any commercially available products can be used.

Specifically, the degree of polymerization is 300 to 3000, the degree of saponification is 60 to
Too% is desirable.

Next, as the organic peroxide, NiR'-07-0-R
2゜OO 111 R3-C-0-0-R4, R5-C-0-0-C-R6
1 (wherein R1, R2, R3, R4, R5, and R' represent hydrogen, an alkyl group, or a phenyl group), etc. can be used.

For example, methyl ethyl ketone peroxide, methyl isobutyl peroxide, acetyl, No-oxide, benzoyl peroxide, p-chlorobenzoyl peroxide, imbutyryl peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, Di-tert-butyl peroxide, tert-butyl cumyl peroxide, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl peracetate, tert-butyl perisobutyrate, tert-butyl ciba- Examples include oxyphthalate and diisopropyl peroxydicarbonate.

These organic peroxides can be used alone or in combination of two or more.

The quantitative proportions of EVA, polyvinyl alcohol, and organic peroxide are determined in relation to the specific use of the resin composition, taking into consideration its melt viscosity, processability, mechanical strength, and other factors.

Specifically, polyvinyl alcohol is preferably used in an amount of 1 to 50 parts by weight based on 100 parts by weight of EVA.

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 is 0.00 parts by weight per 100 parts by weight of EVA.
005 to 5.0 parts by weight, more preferably 0.01 to 2 parts by weight
．． The amount is within the range of 0 parts by weight.

If the amount of organic peroxide is less than the above lower limit, the effect will not be exhibited and both compatibility and adhesive strength will be poor.

In addition, if the amount exceeds the upper limit, crosslinking of EVA progresses,
The melt index of the resulting composition is significantly reduced,
Molding becomes extremely difficult.

It is also possible to use a combination of two or more types of EVA and two or more types of polyvinyl alcohol.

Next, the present invention will be concretely explained by examples, but the present invention is not limited in any way.

Example 1 The following formulation was kneaded using a 3-inch roll.

EVA 5 (Bi' (melt index 209/: r dew) vinyl acetate content
20 Heavy Industries Vicat Softening point 57°C 25g of 20% polyvinyl alcohol aqueous solution (degree of oxidation 89%) 1500 Dicumyl peroxide After melting O, OS & EVA, add an aqueous solution of polyvinyl alcohol and dicumyl peroxide. The mixture was kneaded at ℃ for 10 minutes.

The melt index of the resulting composition was 3.5i/10
It was a minute.

This polymer was sandwiched between two 0.3 mm aluminum plates and thermocompression bonded at 150° C. and 100 kg/crit.

Al/Al at this time! T peel strength is 18.7kV/
It was 25 mm.

In addition, the Al/A, IT peel strength of the EVA used was 2.
It was 5kg/25cm.

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

The obtained polymer had poor compatibility, became opaque, and had a tart index of 13.3 g710 min, kl/A, lT
The peel strength was 5.2 kg/25 mm.

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

The obtained polymer has a melt index of 4.5 g/10
kl/AIT peel strength in minutes is 4. It was s kg/25 tomo.

Example 2 The same procedure as in Example 1 was carried out except that the amount of polyvinyl alcohol aqueous solution was changed to 50 g. As a result, the melt index was 2.59 g/l 0 min, and the kl/AIT peel strength was 16.
It was 1 kg/25 friends.

Example 3 The same procedure as in Example 1 was carried out, except that the EVA was changed to one with a vinyl acetate content of 32% by weight, a melt index of 30g/10min, and a Vicat softening point of 40°C or less, resulting in a melt index of 5.65g/10min. , All/14.
The IT peel strength was 18.2 kg and 725 mm.

Comparative Example 3 The same procedure as in Example 3 was conducted except that no organic peroxide was used.

The resulting polymer had poor compatibility, was opaque, had a tart index of 22.39/10 minutes, and an Al/AIT peel strength of 5.8 kg/25 mm.

Example 4 Polymerization of polyvinyl alcohol, 11500. Saponification degree x
The same procedure as in Example 1 was carried out except that oo% was used.

The resulting polymer had a melt index of 2.47 g/
l 0 minutes, All/AIT peel strength is 16.5 kg/2
It was in 5th order.

Claims (1)

[Scope of Claims] 1. Obtained by mixing 1 to 50 parts by weight of polyvinyl alcohol to 100 parts by weight of vinyl copolymerate in the presence of 0.005 to 5.0 parts by weight of an organic peroxide. A resin composition with excellent adhesive properties. 2 The degree of polymerization of polyvinyl alcohol is 300 to 3.00
0, and the degree of saponification is 60 to 100%. 3 The vinyl acetate content of the ethylene-vinyl acetate copolymer is 1 to 60 by weight, and the tart index is 0.1 to 50.
The composition according to claim 1 or 2, which has a heating time of 0.9/10 minutes.