JPH0539295A - Surface-treating agent for metal - Google Patents

Abstract

PURPOSE:To obtain the subject treating agent having excellent rust-proofing action on metal surface and heat-resistance, capable of improving the adhesivity between metal and a resin substrate and useful especially as a silane-coupling agent for copper foil by using a specific imidazole silane compound as an active component. CONSTITUTION:The objective treating agent contains an imidazole silane compound of formula (R and R' are H or 1-20C alkyl; R'' is methyl or ethyl; (n) is 1-3) as an active component. The compound of formula is e.g. N- imidazolemethyltrimethoxysilane. The compound of formula can be produced by reacting an-imidazole or its derivative (e.g. imidazole and 2-methylimidazole) with a silane compound such as chloromethyl trimethoxysilane in the presence of a dehydrochlorination agent (e.g. triethylamine) at room temperature to 200 deg.C for 0.5-30 hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment agent for preventing rust or improving adhesion of a metal surface, and more particularly to a silane coupling agent for copper foil used for copper clad laminates for printed circuits.

[0002]

2. Description of the Related Art A copper clad laminate for a printed circuit is formed by laminating a paper-phenol resin-impregnated base material or glass-epoxy resin-impregnated base material on a copper foil by heating and pressing, and etching this. A board for electronic equipment is made by forming a circuit network and mounting an element such as a semiconductor device on the circuit network.
In these processes, adhesion of copper foil and substrate, heating, immersion in acid or alkaline liquid, application of resist ink, soldering, etc. are performed, so copper foil has adhesiveness, heat resistance, chemical resistance. Performance such as is required. Further, it is required that the copper foil should not be oxidized and discolored during storage.

In order to meet these requirements, various surface treatment methods for copper foil have been proposed. For example, a brass layer forming treatment of a copper foil (Japanese Patent Publication No. 51-35711, 54-67).
No. 01), chromate treatment, zinc-chromium group mixture coating treatment of zinc or zinc oxide and chromium oxide (Japanese Patent Publication No. 58-7077), and a silane coupling agent is applied to these. A method for improving the adhesion between the copper foil and the resin substrate has also been proposed (Japanese Patent Publication 2-1).
9994, JP-A-63-183178, and JP-A-2-26097).

As this type of silane coupling agent,
Vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N- 2- (aminoethyl)-
3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-
Mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane and the like are known ("Latest Technology of Polymer Additives", pages 120-134, CMC,
Published January 6, 1988).

[0005]

[Problems to be Solved by the Invention] However, since the printed circuit is becoming denser recently, the adhesiveness and other properties required for the copper foil for the printed circuit used are becoming more and more severe. Sufficiently satisfactory results have not been obtained even by surface treatment with a ring agent. As a result of intensive studies conducted by the present inventors in view of the present situation, it was found that a silane compound having an imidazole ring has an excellent anticorrosive action on a metal surface and significantly improves the adhesiveness between the metal and the resin substrate. It was

The present invention has been made on the basis of such findings, and an object of the present invention is to have excellent heat resistance, a high rust preventive action on a metal surface, and a markedly improved adhesion between a metal and a resin substrate. Another object of the present invention is to provide a metal surface treating agent capable of achieving the above, particularly a silane coupling agent for copper foil.

[0007]

The present invention has the following general formula:
(I)

[Chemical 2] (R and R ′ are hydrogen or an alkyl group having 1 to 20 carbon atoms, R ″ is a methyl or ethyl group, and n is an integer of 1 to 3) and an imidazole silane compound is used as an active ingredient. And a silane coupling agent for copper foil containing the above-mentioned imidazole silane compound as an active ingredient.

Typical examples of the imidazolesilane compound represented by the above general formula (I) are shown below. N-imidazolemethyltrimethoxysilane, N-2-
Methylimidazole methyltrimethoxysilane, N-2
-Ethylimidazole methyltrimethoxysilane, N-
2-iso-propylimidazolemethyltrimethoxysilane, N-2-ethyl-4-methylimidazolemethyltrimethoxysilane, N-2-undecylimidazolemethyltrimethoxysilane, N-2-heptadecylimidazolemethyltrimethoxysilane, N-imidazolemethyltriethoxysilane, N-2-methylimidazoleethyltrimethoxysilane, N-2-ethylimidazolemethyltriethoxysilane, N-2-iso-propylimidazolemethyltriethoxysilane, N-2
-Ethyl-4-methylimidazolemethyltriethoxysilane, N-2-undecylimidazolemethyltriethoxysilane, N-2-heptadecylimidazolemethyltriethoxysilane, 2- (N-imidazole) ethyltrimethoxysilane, 2- (N-2-methylimidazole) ethyltrimethoxysilane, 2- (N-2-ethylimidazole) ethyltrimethoxysilane, 2- (N
-2-iso-propylimidazole) ethyltrimethoxysilane, 2- (N-2-ethyl-4-methylimidazole) ethyltrimethoxysilane, 2- (N-2-undecylimidazole) ethyltrimethoxysilane, 2
-(N-2-heptadecylimidazole) ethyltrimethoxysilane, 2- (N-imidazole) ethyltriethoxysilane, 2- (N-2-methylimidazole) ethyltriethoxysilane, 2- (N-2-ethyl) Imidazole) ethyltriethoxysilane, 2- (N-2-i
So-propylimidazole) ethyltriethoxysilane, 2- (N-2-ethyl-4-methylimidazole)
Ethyltriethoxysilane, 2- (N-2-undecylimidazole) ethyltriethoxysilane, 2- (N-
2-heptadecylimidazole) ethyltriethoxysilane, 3- (N-imidazole) propyltrimethoxysilane, 3- (N-2-methylimidazole) propyltrimethoxysilane, 3- (N-2-ethylimidazole) propyltrimethoxysilane Methoxysilane, 3- (N-2-is
o-Propylimidazole) propyltrimethoxysilane, 3- (N-2-ethyl-4-methylimidazole)
Propyltrimethoxysilane, 3- (N-2-undecylimidazole) propyltrimethoxysilane, 3-
(N-2-heptadecylimidazole) propyltrimethoxysilane, 3- (N-imidazole) propyltriethoxysilane, 3- (N-2-methylimidazole)
Propyltriethoxysilane, 3- (N-2-ethylimidazole) propyltriethoxysilane, 3- (N-
2-iso-propylimidazole) propyltriethoxysilane, 3- (N-2-ethyl-4-methylimidazole) propyltriethoxysilane, 3- (N-2-
Undecylimidazole) propyltriethoxysilane, 3- (N-2-heptadecylimidazole) propyltriethoxysilane.

These imidazole silane compounds include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-iso-propylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole and the like. Imidazole or a derivative thereof with chloromethyltrimethoxysilane, chloromethyltriethoxysilane, 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-
It can be easily obtained by reacting silanes such as chloropropylethyltriethoxysilane in the presence of a dehydrochlorination agent. That is, the imidazole derivative and silanes are mixed in a molar ratio of 0.1 to 10 and a dehydrochlorinating agent is added thereto in a range of 0.1 to 10 mol times that of the imidazole, and the temperature is in the range of room temperature to 200 ° C. Then, it is recommended to react for 0.5 to 30 hours. As the dehydrochlorinating agent, an amine compound such as triethylamine or tripropylamine can be used, but since the imidazole derivative itself which is the starting material compound for this reaction acts as the dehydrochlorinating agent, the amount of this reaction starting material By increasing the amount, it can also serve as a dehydrochlorination agent. This reaction does not necessarily require a solvent, but an organic solvent such as dioxane may be used as a reaction solvent.

The present invention uses the above-mentioned imidazole silane compound as a metal surface treating agent. In this case, the target metal is not particularly limited, and various metals can be provided with an effect of preventing rust or improving adhesion. It can be used as an adhesion improver or a rust preventive when it is bonded to a synthetic resin or the like. However, this imidazole silane compound is particularly suitable for use as a surface treatment agent for copper, and particularly when used as a silane coupling agent for copper foil used for copper clad laminates for printed circuits, the effect of the present invention is sufficiently obtained. Can be demonstrated to. When using this imidazole silane compound as a silane coupling agent for copper foil, it may be directly applied to the copper foil, but the surface of the copper foil is roughened, the copper foil is subjected to a brass layer formation treatment, and chromate is used. It can also be applied to the treated one and the one treated with the zinc-chromium group mixture. By performing such a treatment in advance, the effects of the present invention, such as the improvement of adhesiveness, can be further improved.

The above-mentioned imidazole silane compound may be directly coated on the metal surface as it is, but water, alcohols such as methanol and ethanol, and a solvent such as tetrahydrofuran, acetone, ethyl acetate and toluene may be used for 0.0
It is convenient and preferable to dilute so as to be 01 to 20% by weight and apply the solution by dipping a metal in this solution. still,
This imidazole silane compound may be used alone, or a plurality of imidazole silane compounds may be mixed and used, or may be mixed with another rust preventive agent, a coupling agent or the like.

[0012]

The present invention will be specifically described with reference to the following examples.

Production Example 1 (Synthesis of Imidazole Silane Compound) 4.0 g (0.02 mo) of 3-chloropropyltrimethoxysilane was added to 2.7 g (0.04 mol) of imidazole.
1) was added, and the mixture was reacted by stirring at a temperature of 150 ° C. for 15 hours. After the reaction is complete, distillation is performed to remove the hydrochloride. In order to further remove unreacted imidazole from the obtained distillate, the distillate was kept at 95 ° C., and 3-glycidoxypropyltrimethoxysilane (epoxysilane) 7.
9 g was added dropwise, the mixture was reacted with stirring for 1 hour, and distilled to give 3- (N
-Imidazole) propyltrimethoxysilane (hereinafter referred to as "imidazole silane") (0.9 g, yield 19% by weight) was obtained.

Example 1 (1) Heat resistance test An electrolytic copper foil (thickness: 75 μm, 4.5 × 4.5 cm) was degreased with acetone and washed with a 3% aqueous sulfuric acid solution. A 6 wt% methanol solution of the imidazole silane obtained in Production Example 1 was applied onto this copper foil with a spinner to prepare a thin film of imidazole silane having a thickness of 0.3 μm, which was used as a test piece.

The test pieces were tested at 180 ° C and 200 ° C, respectively.
The sample was placed in a constant temperature bath at temperatures of 220 ° C., 220 ° C. and 240 ° C. for 30 minutes for heat treatment, and the degree of discoloration after heating was observed to evaluate heat resistance. The results are shown in Table 1.

[0016]

[Table 1]

(2) Moisture resistance test In the same manner as in the heat resistance test, the test piece coated with imidazole silane was placed in a constant temperature bath at a temperature of 80 ° C. and a humidity of 95% for 24 hours, and the degree of discoloration was observed to check the moisture resistance. evaluated. The results are also shown in Table 1.

(3) Adhesion Test A copper foil (25 × 25 cm) obtained by plating an electrolytic copper foil (33 μm) with a zinc-chromium group mixture was immersed in a 0.4 wt% methanol solution of imidazolesilane. This was hung with a clip to remove excess liquid, and then dried in a dryer at 110 ° C. for 5 minutes. This was bonded to a substrate in which glass fiber cloth was impregnated with an epoxy resin using an epoxy adhesive, and the normal peel strength was measured by the method specified in JIS C6481. The results are shown in Table 2.

[0019]

[Table 2]

Comparative Examples 1 and 2 In place of imidazolesilane in Example 1, 3-glycidoxypropyltrimethoxysilane (hereinafter referred to as "epoxysilane") commercially available as a silane coupling agent.
A copper foil coated with a 6% by weight methanol solution in the same manner as in Example 1 and a copper foil with no coating (hereinafter referred to as “blank”) in the same manner as in Example 1 A moisture resistance test was conducted. The results are also shown in Table 1.

Further, the same adhesiveness test as in Example 1 was conducted on the ones which were subjected to the immersion treatment using epoxysilane instead of the imidazolesilane and those which were not subjected to the immersion treatment, and the results are shown in Table 2.

From the results shown in Table 1, the copper foil surface-treated with the imidazole silane compound of the present invention shows little discoloration during heating and high humidity, and has excellent heat resistance and rust preventive action. It can be seen that the effect of improving the adhesiveness with the resin substrate is more excellent.

[0023]

The surface treatment agent comprising the imidazolesilane compound of the present invention has excellent heat resistance and rust preventive action, and can significantly improve the adhesion between the metal and the resin substrate. It is useful as a silane coupling agent for copper foil.

Claims (2)

[Claims] 1. The following general formula (I): (R and R ′ are hydrogen or an alkyl group having 1 to 20 carbon atoms, R ″ is a methyl or ethyl group, and n is an integer of 1 to 3) and an imidazole silane compound is used as an active ingredient. Metal surface treatment agent. 2. A silane coupling agent for copper foil, which comprises the imidazolesilane compound represented by the general formula (I) according to claim 1 as an active ingredient.