JPH07103349B2 - Pressure-sensitive or heat-sensitive adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure-sensitive or heat-sensitive adhesive having particularly excellent adhesive strength.

(Prior Art) An acrylic pressure-sensitive adhesive using a (meth) acrylic acid ester-based polymer having a (meth) acrylic acid alkyl ester such as butyl acrylate or 2-ethylhexyl acrylate as a main component has an adhesive force. It is widely used because it has good adhesiveness such as cohesive strength and aging resistance such as heat resistance and weather resistance.

As a method of improving the adhesive strength of such an acrylic pressure-sensitive adhesive, generally, in addition to appropriately adjusting the monomer composition and the degree of polymerization of the (meth) acrylic acid ester-based polymer, a method of adding a tackifying resin is used. To be taken. But,
Addition of a tackifying resin improves the adhesive strength, but often causes problems such as heat resistance and cold resistance.

Japanese Examined Patent Publication (Kokoku) No. 63-28114 discloses an acrylic acid ester-based polymer mainly composed of an alkyl acrylate such as butyl acrylate and 2-ethylhexyl acrylate.
Disclosed is a pressure-sensitive adhesive which is improved in adhesive strength by adding a homopolymer of vinyl lactam such as 1-vinyl-2-pyrrolidone and imparts water vapor permeability and hot melt coatability. .

(Problems to be solved by the invention) However, in such a pressure-sensitive adhesive, the acrylic ester-based polymer and the vinyl lactam homopolymer have poor compatibility, so that both are easily separated, and the adhesive strength, etc. There is a problem that the performance cannot be sufficiently improved and exhibited.

The present invention solves the above problems, and an object of the present invention is to provide a pressure-sensitive or heat-sensitive adhesive having particularly excellent adhesive strength.

(Means for Solving the Problems) The pressure-sensitive or heat-sensitive adhesive of the present invention comprises a (meth) acrylic acid ester-based polymer containing a (meth) acrylic acid alkyl ester as a main component, and vinyl acetate-1-vinyl acetate. A 2-pyrrolidone copolymer is blended to achieve the above object.

In the present invention, as the (meth) acrylic acid ester-based polymer containing an alkyl (meth) acrylate as a main component, a (meth) acrylic acid ester-based polymer used in a known acrylic pressure-sensitive adhesive is used. Are all available.

As such a (meth) acrylic acid ester-based polymer, for example, an adhesive polymer having a relatively low glass transition temperature (about -50 ° C or less) such as butyl acrylate and 2-ethylhexyl acrylate can be formed (meth ) Acrylic acid alkyl ester is the main component, and as a component for improving the cohesive force, methyl acrylate, methyl methacrylate, vinyl acetate and the like have a relatively low glass transition temperature (about 0
A polymer obtained by copolymerizing a polymerizable monomer capable of forming a polymer is preferably used.

When the content of 1-vinyl-2-pyrrolidone in the vinyl acetate-1-vinyl-2-pyrrolidone copolymer blended with the (meth) acrylic acid ester-based copolymer is small, sufficient adhesive strength can be obtained. 20 to 80 because it becomes difficult to obtain cold resistance and solder heat resistance when it increases,
Mol% is preferable, and its glass transition temperature is preferably 50 to 90 ° C.

Such vinyl acetate-1-vinyl-2-pyrrolidone copolymer is difficult to obtain sufficient adhesive strength when the amount is small, and when the amount is large, the Tg of the pressure-sensitive adhesive increases, and the pressure-sensitive adhesive becomes hard, so cold resistance is obtained. 10 parts by weight per 100 parts by weight of the (meth) acrylic acid ester-based polymer.
-80 parts by weight are blended.

When the blending amount is about 5 to 30 parts by weight, the room temperature tackiness of the (meth) acrylic acid ester-based polymer is maintained and the pressure-sensitive adhesive is obtained. On the other hand, if the blending amount is about 30 parts by weight or more, the room temperature tackiness decreases with an increase in the blending amount, resulting in a heat-sensitive adhesive. In particular, a compound having a melt viscosity of about 50,000 cps or less at 150 ° C. becomes a water-insoluble heat-sensitive adhesive that can be applied to a sheet base material by a conventional hot-melt coating apparatus.

In addition, in the blend of the above-mentioned (meth) acrylic acid ester-based polymer and vinyl acetate-1-vinyl-2-pyrrolidone copolymer, tetrakis- (2,4-di-tert-butyl-phenyl)- Additives generally used in conventional adhesives such as stabilizers such as 4,4′-biphenylene-diphosphonite, colorants, crosslinking agents, and fillers can be used.

The adhesive composition thus prepared is made into a pressure-sensitive or heat-sensitive adhesive by a method similar to the usual method for producing a pressure-sensitive adhesive.

For example, the compound of the above adhesive is dissolved in an organic solvent to form a solution, or heat-melted without using an organic solvent,
This is usually used plastic film, paper,
For example, a sheet-shaped pressure-sensitive or heat-sensitive adhesive is formed by applying it on a base material such as cellophane, cloth, non-woven fabric, metal foil, or a temporary release sheet such as release paper and then drying it. When a temporary release sheet such as the release paper is used, a sheet-like adhesive having a release sheet temporarily attached but no base material can be obtained.

(Function) In the present invention, the vinyl acetate component of the vinyl acetate-1-vinyl-2-pyrrolidone copolymer improves the compatibility with the (meth) acrylic acid ester-based polymer and further improves the adhesiveness. Contribute. In addition, the 1-vinyl-2-pyrrolidone component improves the adhesiveness of the (meth) acrylic acid ester-based polymer and imparts water vapor permeability and hot melt heat coatability.

(Example) Hereinafter, the Example of this invention is shown.

<Preparation of blending components> [Acrylic pressure-sensitive adhesive solution A] A solution of an acrylic pressure-sensitive adhesive composed of an acrylate-based polymer containing butyl acrylate as a main component (ethyl acetate /
A toluene mixed solution with a solid content of 33% by weight was used as an acrylic adhesive solution A.

[Acrylic adhesive solution B]

A solution of an acrylic pressure-sensitive adhesive composed of an acrylic acid ester-based polymer containing butyl acrylate and 2-ethylhexyl acrylate as main components (ethyl acetate / toluene mixed solution, solid content 39% by weight) was used as an acrylic pressure-sensitive adhesive solution B. did.

[Vinyl acetate-1-vinyl-2-pyrrolidone copolymer solution] Vinyl acetate-1-vinyl-2-pyrrolidone copolymer (1
A vinyl solution of vinyl-2-pyrrolidone content of 30 mol% and a glass transition temperature of 67 ° C.) was prepared as an ethanol solution (solid content: 50% by weight, manufactured by BASF Corporation, trade name “RUVISCOL VA37E”).

[Polyvinylpyrrolidone solution]

Polyvinylpyrrolidone powder (International Specialty Product
Product.Co), product name "PVP K-30" and "PVP
K-120 ”) in ethanol and dissolve the solid content to 3
A 0% by weight polyvinylpyrrolidone solution was obtained (hereinafter referred to as "PVP (K-30) solution" and "PVP (K-120) solution", respectively).

Examples 1 to 2 and Comparative Examples 1 to 6 According to the blending composition shown in Table 1, 100 parts by weight of the solid content of the acrylic pressure-sensitive adhesive solution A was added to the vinyl acetate-1-
The solid content of the vinyl-2-pyrrolidone copolymer solution is 0 parts by weight, 20 parts by weight, 40 parts by weight and 100 parts by weight, and the solid content of the polyvinylpyrrolidone solution is 20 parts by weight and 40 parts by weight, respectively. And the adhesive solution was prepared. An adhesive sheet sample was prepared by applying the adhesive solution on a polyester film having a thickness of 25 μm so as to have a solid content thickness of 40 μm and drying.

After the above adhesive sheet sample was manually pressure-bonded to a steel plate with a thickness of 1.5 mm and a polyimide film with a thickness of 25 μm, 120
℃, 2kg / cm ² between thermocompression bonding rollers to bond and
According to Z-0237, Shopper tensile tester (pull speed 30
180 ° angle peel test under conditions of 230 ° C and 65% RH (0 mm / min) to measure the adhesive strength (g / 15 mm width) (hereinafter referred to as "steel plate adhesive strength" and "polyimide film adhesive strength", respectively). To). Further, according to JIS Z-0237, the ball tack value by the ball rolling method was measured by an inclined ball tack tester (hereinafter referred to as "ball tack"). Further, the compatibility of the solution and the adhesive sheet sample was visually measured (hereinafter referred to as “compatibility”). However, the evaluation criteria were “◯” if transparent, “Δ” if slightly cloudy, and “x” if cloudy. The above results are shown in Table 1.

Examples 3 to 4 and Comparative Examples 7 to 10 Adhesive solutions were prepared by the same procedure except that the acrylic pressure sensitive adhesive solution A was used instead of the acrylic pressure sensitive adhesive solution A according to the composition of Table 1. did. An adhesive sheet sample was prepared by applying the adhesive solution on a polyester film having a thickness of 25 μm so as to have a solid content thickness of 40 μm and drying.

For the above adhesive sheet sample, the adhesive strength to the epoxy resin-impregnated glass cloth as well as the adhesive strength to the steel plate was measured in the same manner as in Example 1.

In addition, the above adhesive solution was coated on a release paper with a solid thickness of 40 μm.
So that the adhesive sheet sample is prepared by drying
The epoxy resin-impregnated glass cloth and a polyimide-based flexible printed circuit board are pasted through the adhesive sheet sample, passed through a thermocompression roller of 120 ° C. and 2 kg / cm ² to be adhered, and further the printed circuit. The substrate was immersed in a solder bath at 260 ° C. for 5 seconds with the substrate facing downward, and the heat resistance of the solder was visually evaluated from the swelling phenomenon and the like in four grades of ⊚, ◯, Δ and ×. The compatibility was also evaluated in the same manner. The above results are shown in Table 2.

(Effects of the Invention) As described above, the adhesive of the present invention is a copolymer of (meth) acrylic acid ester containing (meth) acrylic acid alkyl ester as a main component, and vinyl acetate-1-vinyl-2-pyrrolidone copolymer. Since the polymers are blended, both polymers are compatible with each other and both polymers do not separate. Therefore, the performance possessed by both polymers is sufficiently exhibited, and particularly the effect of improving the adhesive strength is large.

Further, in the present invention, the improvement method by blending both the above polymers is adopted, and the blending ratio can be easily changed as compared with the improvement method by the copolymerization of various monomers. Therefore, it has an advantage that various properties such as water vapor permeability and heat resistance as well as the adhesive strength can be easily set to desired levels and the applicability is widened.

Therefore, the adhesive of the present invention is suitably used not only for general adhesive applications but also for adhesion of plywood, adhesion of flexible printed circuit boards, adhesion of other electric and electronic parts, medical tape having excellent water vapor permeability, and the like.

Claims (1)

[Claims] 1. A vinyl acetate-1-vinyl-2-pyrrolidone copolymer is contained in an amount of 10 to 80 parts by weight based on 100 parts by weight of a (meth) acrylic acid ester-based polymer containing a (meth) acrylic acid ester as a main component. A pressure-sensitive or heat-sensitive adhesive characterized by being blended.