JPH0333174A - Acrylic adhesive composition - Google Patents

Abstract

PURPOSE:To improve the adhesive strength, flexibility, heat resistance, and solvent resistance by compounding a specific acrylic resin, an epoxy resin, and a melamine resin. CONSTITUTION:The title compsn. comprises 10-50wt.% (meth)acrylonitrile, 45-85wt.% ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, or a mixture of these monomers, and 2-10wt.% (meth)acrylic acid and/or itaconic acid are radical-copolymerized to give an acrylic resin, 75-97wt.% the resulting acrylic resin, 2-15wt.% epoxy resin which is solid at room temp. (e.g. bisphenol A epoxy resin with an epoxy equivalent of 130-2000), 1-10wt.% melamine resin (e.g. methylated melamine resin), and if necessary a curing accelerator (e.g. 2-ethyl-4-methylimidazole).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an acrylic adhesive composition,
In particular, the present invention relates to an acrylic adhesive composition that has a high adhesive strength and is excellent in flexibility, heat resistance, and solvent resistance.

<Conventional technology> Adhesives are widely used in electrical equipment, civil engineering and construction materials, etc., but in recent years, adhesives have been particularly used in electronic computers, communication equipment, measurement and control equipment, cameras, watches, car electronics, and various types of A.
Adhesives are frequently used in electrical equipment such as appliances, home appliances, aircraft instruments, and medical equipment. However, in recent years, as electronic devices have become denser and their wiring has become more precise, adhesives with higher adhesive strength, electrical properties, heat resistance, solvent resistance, and flexibility are required to improve their reliability. Became. Additionally, in order to improve productivity, there is a need for adhesives that can be bonded at lower temperatures and in a shorter time.

<Problem of the Invention> However, it has been extremely difficult to find an adhesive that simultaneously satisfies adhesiveness, heat resistance, and flexibility among these required properties. For example, in the case of epoxy resin compositions that are widely used as adhesives, it is necessary to use plasticizers and flexible epoxy resins in combination to obtain excellent flexibility. Characteristics such as these decrease.

To solve these problems, adhesives made of acrylic resin and phenol resin or melamine resin have been proposed. Furthermore, adhesives made of specific acrylic resins and epoxy resins have been proposed (Japanese Patent Laid-Open No. 174211/1983).
No. 13).

However, these adhesives require high temperature and long processing (pressing time) in order to obtain a higher degree of adhesiveness.

As a result of intensive studies to solve the above problems, the present inventors have found that a composition made of a combination of a special acrylic resin, an epoxy resin, and a melamine resin satisfies these characteristics. The inventors have discovered that the present invention is possible. That is, the present invention
(a) 10 to 50% by weight of acrylonitrile or methacrylonitrile or a mixture thereof; (b) 4
an acrylic copolymer of 5 to 85% by weight of ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate or mixtures thereof, and (C) 2 to 10% by weight of acrylic acid, methacrylic acid or itaconic acid or mixtures thereof; This is an acrylic adhesive composition consisting of a resin (A), an epoxy resin (B), and a melamine resin (C).

The acrylic resin (A) used in the present invention is (a) 10
~50% by weight of acrylonitrile or methacrylonitrile or mixtures thereof, c) 48-85% by weight
ethyl acrylate), butyl acrylate or 2
- ethylhexyl acrylate or mixtures thereof and (C) a copolymer containing 2 to 10 weight of acrylic acid, methacrylic acid or itaconic acid or mixtures thereof.

This can be synthesized by a conventional radical polymerization method such as emulsion polymerization, suspension polymerization, or solution polymerization. Further, the epoxy resin used in the present invention is a polyfunctional epoxy compound having crosslinking properties, and preferably exhibits solid properties at room temperature. This epoxy resin can be derived from bisphenol A type, phenol or cresol novolac type, diaminodiphenylmethane type, etc. as a basic skeleton, but in consideration of economic efficiency and workability, bisphenol A type epoxy resin is used. Epoxy equivalent is 180-20
00 is generally used.

Furthermore, the melamine resin used in the present invention is a commercially available melamine resin, and all melamine resins such as methylated melamine resin, butylated melamine resin, and methyl-butylated mixed ether type melamine resin can be used, but it is preferable that the melamine resin has a solid state at room temperature. This is a methylated melamine resin shown below.

Also preferred is a melamine compound having crosslinking properties.

The blending ratio of these resins is 75 to 97% by weight of acrylic resin, 2 to 15% by weight of epoxy resin, and 1 to 10% of melamine resin.
It is 10% by weight. When the melamine resin content is less than 1% by weight, the adhesive strength is poor and high adhesion cannot be obtained by short-time processing (pressing), and when it is more than 10% by weight, the heat resistance and flexibility are poor.

Furthermore, if the epoxy resin content is less than 2% by weight, the adhesive strength will be poor, and if it is more than 15% by weight, the heat resistance and flexibility will be poor.

Further, as a means for improving heat resistance, a curing accelerator may be used as necessary. As a curing accelerator, 2-ethyl-
Imidazoles and derivatives thereof such as 4-methylimidazole and 2-phenyl-4-methylimidazole, 2
- Imidacillins such as ethylimidacillin, tertiary amines such as dimethylbenzylamine, etc. are generally used, but are not limited to these.

The adhesive composition may be in any form such as film, water dispersion, or solution. - As for the simple manufacturing method, the acrylic copolymer of the above monomer combination is synthesized by emulsion polymerization, and the specified epoxy resin and melamine resin are added and mixed to this emulsion, and then the desired acrylic copolymer is added and mixed using an alkali thickening formulation. If the viscosity is adjusted, it becomes a water-dispersible adhesive.

In addition, in the solution type, the emulsion obtained by emulsion polymerization is salted out to separate the polymer as a solid, and then dried and then mixed with a specified epoxy resin or melamine resin in a good solvent such as methyl ethyl ketone or methyl isobutyl ketone. A solution having a desired concentration and viscosity may be prepared by mixing and dissolving it. Furthermore, in the case of a film adhesive, it can be obtained by applying a solution of methyl ethyl ketone or methyl isobutyl ketone having the above composition onto a release paper or the like and drying it by a general casting method.

At this time, the film thickness can be freely adjusted in relation to the resin concentration.

If the adhesive is a film, lamination is carried out by heat-pressing; for water-dispersed or solution-type adhesives, it is first applied to the adherend, the water or solvent is thoroughly evaporated, and then the same heat-pressure is applied. Implemented. As for bonding conditions, it is preferable to heat and press under a pressure of 10 to 60 kg/clll, 130 to 200 DEG C., and for 3 to 60 minutes using a normal heat press method.

<Effects> The adhesive composition of the present invention has excellent adhesion, heat resistance, and flexibility, and is particularly useful for polyimide films in flexible printed circuit boards (hereinafter referred to as FPC), sheet coils, tape carriers, etc. It exhibits excellent adhesion effects when adhering to metal foils such as copper foils. Also,
It also exhibits excellent effects in adhering glass epoxy plates, metal plates, and heat-resistant thermoplastic resins used to reinforce FPCs and FPCs and copper-clad flexible plates (hereinafter referred to as FCL).

Furthermore, the adhesive of the present invention provides excellent adhesive properties even when processed (pressing) at low temperatures and for a short time, contributing to improved productivity.

When a polyimide film and a copper foil are bonded using the adhesive composition of the present invention, the bonded sheet is extremely flexible, has a peel strength of 1 kg/0 m or more, and has a soldering heat resistance (
280° C.) for 30 seconds or more. In addition, acids, alkalis,
It also has excellent chemical resistance to trichlene, methylene chloride, etc.

<Examples> The present invention will be explained below with reference to Examples, but the present invention is not limited only to the Examples.

Reference example-l 500- equipped with a reflux condenser, thermometer, and nitrogen gas introduction pipe
- Into a flask, charge 18.6 g of acrylonitrile, 77 g of n-butyl acrylate, 4.3 g of methacrylic acid, and 1.0 g of sodium dioctyl sulfosuccinate,
Add 200 g of distilled water and emulsify with stirring. Add to this 0.3 g of potassium persulfate and 0.3 g of sodium bisulfite.
After adding 1 g of nitrogen gas and completely replacing the air inside, the temperature was raised to 60° C. over 1 hour, and polymerization was carried out for 3 hours under a nitrogen gas stream.

After polymerization, cool to room temperature and add about 30 g of sodium chloride.
was gradually added to salt out the polymer, and the process of filtration and water washing was repeated three times, followed by drying to form a solid acrylic copolymer 96.
get g.

Reference Example 2 32 g of the acrylic polymer obtained in Reference Example 1 was dissolved in 264 g of methyl ethyl ketone to obtain a transparent viscous liquid. Add 4.4 g of Sumiepoxy ESA-011 (Sumitomo Chemical Bisfilm A type solid epoxy resin) to this viscous liquid and 0.8 g of Sumimaru M-4O3 (Sumitomo Chemical methylated melamine resin, diluted with 80% xylene). Add and stir to dissolve to obtain a transparent viscous liquid.

Reference Example-3 32 g of the acrylic polymer obtained in Reference Example-1 was dissolved in 264 g of methyl ethyl ketone, and Sumimaru M-40S
2.4g of Sumiepoxy ESA-011 and 4.4g of Sumiepoxy ESA-011
Add and stir to dissolve to obtain a transparent viscous liquid.

Reference Example-4 32 g of the acrylic polymer obtained in Reference Example-1 was dissolved in 264 g of methyl ethyl ketone, and Sumiepokin ESA-
Add 4 g of 011 and dissolve with stirring to obtain a transparent viscous liquid.

Example-1 The viscous liquid obtained in Reference Example-2 is cast onto polyprocoat release paper using a box coater, and dried at a temperature of room temperature to 130°C to obtain a polymer film with a thickness of 30 to 50 microns. .

■ The obtained film adhesive was sandwiched between Kapton ■ polyimide film (steel foil made by Du pant Products Co., Ltd. (TSTO treated product by Furukawa Circuit Foil Co., Ltd.),
kg/col, L was hot pressed for 40 minutes at 80°C. The peel strength and solder heat resistance of the obtained bonded product were measured. The results are shown in Table 1.

■ The obtained film adhesive was sandwiched between the same adherends as in ■, and heated at 25 kg/cal and 160°C for 3 hours.
A heat press was performed for 1 minute. The peel strength and solder heat resistance of the obtained bonded product were measured. The results are shown in Table 1.

■ Spread the obtained film adhesive on an aluminum plate (0.9 m
Scissors between m1) and FCL (polyimide surface manufactured by Toshinu Pant), 30 kg/cIIl, 16
Heat pressing was performed for 3 minutes at 0°C. After a predetermined period of time, the press pressure was released, and the presence or absence of peeling (blister) on the adhesive surface was immediately checked visually. The results are shown in Table 1.

Example-2 The viscous liquid obtained in Reference Example-3 was made into a polymer film in exactly the same manner as in Example-1, and then Example-1
Peel strength, solder heat resistance, etc. were measured in exactly the same manner as above.

Comparative Example-1 The viscous liquid obtained in Reference Example-4 was made into a polymer film in exactly the same manner as in Example-1, and then Example-1
Peel strength, solder heat resistance, etc. were measured in exactly the same manner as above.

Comparative Example-2 100 g of Sumiepoxy ESA-011 (bisphenol A type solid epoxy resin made by Sumitomo Chemical), 18 g1 of non-reactive dibutyl phthalate as a flexible finishing agent, 4 g of dicyandiamide, 2-ethyl-4-methylimidazole 0.5g to 45g methyl cellosolve and 10g
was dissolved in methyl ethyl ketone to obtain a cast film in the same manner as in Example-1.

Thereafter, a bonded product was obtained in exactly the same manner as in Example-1, and peel strength, solder heat resistance, etc. were measured.

The results are shown in Table 1.

Comparative Example 3 A commercially available film adhesive (Vyralux LF, 50 μm thick, manufactured by Du Pont) consisting of a copolymer of acrylonitrile, butyl acrylate and methacrylic acid, and a phenol resin was used as a polymer film, and Example-1 and Peel strength, solder heat resistance, etc. were measured in exactly the same manner.The results are shown in Sheet 1.

(Margin below)

Claims (1)

[Claims] (a) 10 to 50% by weight of acrylonitrile or
Methacrylonitrile or mixtures thereof, (b) 45
an acrylic copolymer of ~85% by weight of ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate or mixtures thereof; and (c) 2 to 10% by weight of acrylic acid, methacrylic acid or itaconic acid or mixtures thereof. An acrylic adhesive composition comprising a resin (A), an epoxy resin (B), and a melamine resin (C).