JPH09157621A - Adhesive resin composition for cationic electrodeposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition, comprising a cationic group-containing epoxy resin, a pdlyfunctional epoxy resin, a polyvinyl acetal resin and an amino resin, capable of providing an insulating layer and an adhesive layer having a uniform film thickness and excellent in peel strength and solder heat resistance. SOLUTION: This adhesive composition comprises (A) an epoxy resin having cationic groups, (B) an epoxy resin having >=3 epoxy groups (preferably a polyfunctional glycidyl ether type epoxy resin), (C) a polyvinyl acetal resin (preferably a carboxy-modified polyvinyl acetoacetal resin prepared by reacting a part of hydroxyl groups with a carboxylic acid such as itaconic acid) and (D) an amino resin (preferably an etherified melamine resin obtained by modifying a melamine resin with n-butyl alcohol). For example, a reactional product of an epoxy resin, e.g. a bisphenol type with a cationizing agent is cited as the component (A) and diamines having a primary amine such as ethylenediamine at both terminals are preferred as the cationizing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used to bond a metal foil and a laminate in the production of a metal foil-clad laminate.
The present invention relates to an electrodeposition coating type adhesive for metal foil-clad laminates.

[0002]

BACKGROUND OF THE INVENTION Metal foil-clad laminates are commonly used in printed wiring boards for consumer electronic devices. Therefore, the metal foil-clad laminate is required to have solder heat resistance and metal foil peeling strength. The copper foil with an adhesive used in this field is generally formed by applying a resin to a roughened surface with a roll coater or the like and then performing a drying step. Since the adhesive used contains a large amount of solvent, the viscosity,
There are some problems such as the change of the solid content ratio is great and it is difficult to control the adhesive, and it is difficult to make the film thickness uniform due to bending of the copper foil. As one method for solving these problems, a method, which is a general method in the field of coating materials, in which charged particles are dispersed in water and applied by electrophoresis has been developed (JP-A-3-112190, U.S. Pat.
S. P. 4,915,797).

[0003]

However, the disclosed adhesive composition is a composition containing only a commercially available electrodeposition paint and an emulsifier, and does not satisfy the performance required for a metal foil-clad laminate. The present invention
Under these circumstances, it is an object to provide a cationic electrodeposition adhesive composition suitable for a metal foil-clad laminate.

[0004]

In order to find a composition satisfying the performance required for a metal foil-clad laminate, the present invention is a cationic resin in which an amine is added to an epoxy resin, a polyfunctional epoxy resin, a polyacetal resin, and an amino resin. It was found that the performance required for the metal foil-clad laminate is satisfied by using the cationic electrodeposition adhesive having the composition of, and the present invention has been completed. That is, in the present invention, the epoxy resin (A) containing a cationic group has an epoxy group of 1
The present invention relates to a cationic electrodeposition adhesive composition for metal foil-clad laminates, which comprises 3 or more epoxy resin (B), polyvinyl acetal resin (C), and amino resin (D) per molecule. The components constituting the cationic electrodeposition adhesive composition of the present invention will be described below.

The resin having a cationic group as the component A used in the present invention has an amino group necessary for reacting with the component B described below and forming a stable aqueous dispersion. Specific examples include reaction products obtained by reacting an epoxy resin with a cationizing agent. Examples of the above-mentioned epoxy resin include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and those whose side chain or main chain is modified with a flexible resin such as rubber, urethane, polyether, or polyester. These can be used alone or in combination of two or more. The epoxy equivalent of the bisphenol type epoxy resin is not particularly limited, but is preferably 800 or more and less than 2000. When it is less than 800 and 2000 or more, the stability of dispersed particles is low and the particles do not exist stably. Epoxy equivalent 800 or more 200
Within the range of less than 0, a well-balanced one, for example, one having a normal distribution is preferable. Specifically, it is preferable to mix and use those having different epoxy equivalents, for example, those having 950, 1500, 1800 and the like. The blending amount is 30% to 7 based on the total amount of A, B, C and D components.
Used at 0% by weight. If the blending amount is less than 30% by weight,
Normal peel strength and emulsifying dispersibility decrease, while if it exceeds 70% by weight, solder heat resistance decreases.

On the other hand, examples of the cationizing agent for introducing a cationic group into the above epoxy resin include aliphatic, alicyclic or aromatic-aliphatic primary or secondary amines. These react with epoxy groups to form cationic groups. Preferred examples of the cationizing agent include the followings. (1) Primary amines such as methylamine, ethylamine, n- or i-propylamine, monoethanolamine (2) Secondary amines such as diethylamine, diethanolamine, N-methylethanolamine (3) Ethylenediamine, diethylenetriamine, hydroxyethyl Polyamines such as aminoethylamine and dimethylaminopropylamine Among these, diamines having primary amines at both ends are
It is particularly preferable for improving the normal state peel strength and the solder heat resistance.

3 in one molecule of the B component used in the present invention
As the polyfunctional epoxy resin having at least one epoxy group, there are novolac type, glycidyl amine type, glycidyl ether type, or epoxidized type of a polymer of a diene monomer such as butadiene, isoprene, and chloroprene. However, a polyfunctional glycidyl ether resin having three or more epoxy groups in one molecule is particularly preferable for improving solder heat resistance. The compounding amount of the polyfunctional epoxy resin is 10 to 40% by weight, preferably 15 to 30% by weight based on the above criteria. If the compounding amount of the polyfunctional epoxy resin is less than 10% by weight, the solder heat resistance is lowered,
If it exceeds 5% by weight, the normal peel strength is reduced. The C-component polyvinyl acetal resin used in the present invention is obtained by saponifying polyvinyl acetate into polyvinyl alcohol, which is acetalized by reacting it with an aldehyde such as formaldehyde, acetaldehyde or butyraldehyde. The polyvinyl acetal resin used in the present invention is not particularly limited, but for example, polyvinyl formal resin, polyvinyl acetoacetal resin, polyvinyl butyral resin and the like can be used alone or in combination of two or more kinds. Particularly preferred is a carboxy-modified polyvinyl acetoacetal resin obtained by reacting a part of the hydroxyl groups in the polyvinyl acetoacetal resin with a carboxylic acid such as itaconic acid to modify, and when this is used, solder heat resistance can be particularly improved. .

The degree of polymerization of polyvinyl acetal resin is 15
The range of 00 to 2500 is preferable and 180 is more preferable.
It is in the range of 0 to 2200. When the polymerization degree is less than 1500, the solder heat resistance is lowered, and when the polymerization degree is more than 2500, the emulsification dispersibility is lowered. The degree of acetalization of the polyvinyl acetal resin is preferably 65% by weight or more. 65% by weight
If it is less than 100%, both peel strength and solder heat resistance decrease. The blending amount of this resin is preferably 20% by weight or less, and more preferably 5 to 15% by weight, based on the above-mentioned criteria. The amount is 2
If it exceeds 0% by weight, the emulsifying dispersibility will be reduced. As the amino resin of the component D used in the present invention, an etherified amine resin obtained by addition-condensing melamine, guanamine, urea and their derivatives with formaldehyde, and further modifying with alcohol is preferable. Particularly preferred is an etherified melamine resin obtained by modifying the melamine resin with n-butyl alcohol. The amount of the melamine resin used is preferably 20% by weight or less based on the above criteria, and more preferably 5 to 5.
15% by weight. If the blending amount exceeds 20% by weight, the state peel strength decreases.

The aqueous dispersion used in the present invention is obtained by dispersing the above electrodepositable resin and other components in an aqueous medium. The aqueous medium used here may contain water or water and an organic solvent. The organic solvent may be either water-miscible or water-immiscible. Examples of the water-miscible solvent include ethyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, methyl ethyl ketone and the like. Examples of the water-immiscible solvent include xylene, toluene, cyclohexanone, propylene glycol phenyl ether and the like.

In order to disperse the electrodepositable resin in an aqueous medium, the amino group may be protonated with a water-soluble organic acid such as formic acid, acetic acid or lactic acid and dissolved or dispersed in water. Although the amount of the acid used for protonation cannot be strictly specified, the pH of the electrodeposition liquid is 3 to 7, preferably 4 to 6
Acid is added so that it becomes the range of. The aqueous dispersion thus obtained is particularly suitable for cathodic electrodeposition coating. Other flame retardant, filler,
A coupling agent, a curing accelerator, a plasticizer, a surfactant and the like can be added and blended.

As a method and apparatus for performing electrodeposition coating on an adherend using the above aqueous dispersion, U. S. P. 4,915,
797 and Japanese Unexamined Patent Publication No. 3-229893 can be used.
At that time, it is desirable to use a metal foil as a cathode and a stainless steel or carbon plate as an anode. The electrodeposition conditions used are not particularly limited, but generally bath temperature: 2
0 to 30 ° C., voltage 5 to 100 V, preferably 10 to 50
V, and energization time is preferably 5 to 60 seconds.

The pH of the bath is of sufficient value to form a coating which does not break under conditions of voltage application, ie:
The pH is such that the resin does not impair the dispersion and controls the conductivity of the bath. The pH is typically 3-7, more preferably 4-6. The conductivity of the bath is of sufficient value to form a coating film of sufficient thickness. That is, typically 300-
2000 μS / cm, preferably 600 to 1000 μS
/ Cm.

Although the coating film thickness is not strictly limited, a range of 10 to 50 μm is generally suitable based on the cured coating film. After electrodeposition, the adherend is taken out of the bath and washed with water, and then 70 to 200 ° C., preferably 100 to 150
It is preferable to heat cure at a temperature in the range of ° C. The metal foil used here is not particularly limited, but electrolytic copper foil, rolled copper foil and the like are preferable, and these metal foils are surface-treated with a silane coupling agent, a titanate coupling agent or the like. Is preferably used. The metal foil with an adhesive can be laminated on a substrate and heated and pressed by a conventional method to easily produce a metal foil-clad laminate.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. Production Example 1 100 g of G-402 (ester modified product of bisphenol A type epoxy resin having epoxy equivalent of 1350 manufactured by Daicel Chemical Industries, Ltd.), 4 gr of ethylenediamine and 104 gr of butyl cellosolve were placed in a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux condenser. Was charged and reacted at 80 ° C. until the epoxy group disappeared to obtain an epoxy polyamine resin solution (A-1) having a solid content of 50%.

Production Example 2 DER664U (epoxy equivalent of 8) was added to the reactor of Production Example 1.
75-945, bisphenol A type epoxy resin; manufactured by Dow Chemical Co., Ltd.) 100 gr, ethylene diamine 6 gr and butyl cellosolve 106 gr are charged, and reacted at 80 ° C. until the epoxy group is eliminated, and an epoxy polyamine resin solution (A-2) having a solid content of 50%. Got

Production Example 3 DER667 (epoxy equivalent of 16) was added to the reactor of Production Example 1.
00-1950, bisphenol A type epoxy resin; manufactured by Dow Chemical Co., Ltd.) 100 gr, ethylenediamine 3 gr
And 103 g of butyl cellosolve were charged and reacted at 80 ° C. until the epoxy group was removed to obtain an epoxy polyamine resin solution (A-3) having a solid content of 50%.

Production Example 4 DER668 (epoxy equivalent of 20) was added to the reactor of Production Example 1.
00-3500, bisphenol A type epoxy resin; manufactured by Dow Chemical Co., Ltd.) 100 gr, ethylenediamine 2 gr
And 102 g of butyl cellosolve were charged and reacted at 80 ° C. until the epoxy group was removed to obtain an epoxy polyamine resin solution (A-4) having a solid content of 50%.

Example 1 The resin solution obtained in Production Example 1 was mixed with a tetrafunctional epoxy resin, a polyvinyl acetoacetal resin, a melamine resin and butyl cellosolve to prepare a resin solution having a solid content of 40% by weight. Add about 600gr of ionized water,
The mixture was stirred with a homomixer to obtain a stable emulsion having a resin solid content of 10%. The obtained emulsion solution is heated to a bath temperature of 25
The temperature was adjusted to 0 ° C., a stainless steel plate was used as an anode, a copper foil having a length of 10 cm × width of 10 cm × thickness of 35 μm was used as a cathode, and a voltage of 40 V for 30 seconds was applied to carry out electrodeposition. Then, it was dried at 150 ° C. for 2 minutes to produce a copper foil with an adhesive having a coating thickness of 25 μm. Paper on the adhesive side of this copper foil with adhesive
Eight phenol resin prepregs were stacked and heated and pressed by a conventional method to produce a copper-clad paper / phenol resin laminate having a thickness of 1.6 mm. The state of the obtained emulsion, the normal peel strength of the laminate, and the solder heat resistance were tested.

Examples 2 and 3 An electrodeposition bath was prepared in the same manner as in Example 1 with the compounding ratios shown in Table 1, and the performance was evaluated. Comparative Examples 1 to 3 An electrodeposition bath was prepared in the same manner as in Example 1 with the compounding ratios shown in Table 2.

[0020]

[Table 1]

1) Tetrafunctional epoxy resin (made by Yuka Shell Epoxy Co., Ltd.) 2) Itaconic acid modified polyvinyl acetoacetal resin (made by Sekisui Chemical Co., Ltd.) 3) Etherified melamine resin (made by Dainippon Ink and Chemicals Co., Ltd.) Comparative Example 1-3

[0022]

[Table 2]

[0023]

As described above, the cationic electrodeposition adhesive composition for metal foil-clad laminates of the present invention can form an insulating layer / adhesive layer having a uniform film thickness. Further, the adhesive of the present invention has a normal peel strength and solder heat resistance at a level sufficient for a metal foil-clad laminate.

Claims (1)

[Claims] 1. A metal foil-clad comprising an epoxy resin (A) containing a cationic group (A), an epoxy resin (B) containing 3 or more epoxy groups per molecule, a polyvinyl acetal resin (C), and an amino resin (D). A cationic electrodeposition adhesive composition for laminates.