JP2602524B2 - Adhesive composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an adhesive composition having improved heat resistance and adhesiveness.

(Prior Art) Conventionally, an adhesive composition containing a polyvinyl acetal resin such as a polyvinyl butyral resin and a thermosetting resin such as a phenol resin is known (for example, JP-A-55-27342). .

This type of adhesive composition has relatively good heat resistance and adhesiveness, and is widely used as an adhesive for manufacturing laminated boards such as decorative boards and printed boards. For example, a printed circuit board is usually manufactured by applying a solution of the above adhesive composition to a copper foil, drying the solution, laminating this with a thermosetting resin-impregnated base material such as phenol resin-impregnated paper, and thermocompression bonding. Is done.
Then, by etching the copper on the printed circuit board, an electric circuit board is obtained, on which electronic components are attached and soldered.

(Problems to be Solved by the Invention) However, in recent years, as electronic products have become lighter and smaller, circuit density has become higher and automation has been advanced. An immersion is taking place. As a result, there is a problem that thermal deterioration of the substrate and peeling of the circuit pattern are likely to occur, and the above-mentioned conventional adhesive composition is not sufficient, and further improvement in heat resistance and adhesiveness is demanded. ing.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide an adhesive composition having improved heat resistance and adhesiveness.

(Means for Solving the Problems) The adhesive composition of the present invention comprises a polyvinyl acetal resin having a β-dicarbonyl structure in a side chain and a thermosetting resin having a methylol group, whereby The above object is achieved.

In the present invention, a polyvinyl acetal resin having a β-dicarbonyl structure in a side chain refers to a molecule in the polyvinyl acetal resin molecule. It means a resin having a portion. These resins react a polyvinyl alcohol resin with a β-dicarbonyl compound (for example, diketene) to introduce a β-dicarbonyl structure (for example, an acetoacetyl group) into a side chain, and react the resin with an aldehyde. And can be obtained by acetalization.

Further, a polyvinyl alcohol resin is reacted with an aldehyde to form an acetal, and the resin is reacted with a β-dicarbonyl compound (for example, diketene) to introduce a β-dicarbonyl structure (for example, an acetoacetyl group) into a side chain. Can also be obtained.

When diketene is used as the β-dicarbonyl compound, an addition reaction occurs. When an ester is used as the β-dicarbonyl compound, a transesterification reaction occurs between the ester and a polyvinyl alcohol resin or a polyvinyl acetal resin.

In the present invention, an acetoacetylated polyvinyl acetal resin obtained by using a technique disclosed in, for example, Japanese Patent Publication No. Sho 62-1963 and using diketene as the β-dicarbonyl compound is preferably used. The degree of acetoacetylation is preferably from 0.2 to 10% by weight. This degree of acetoacetylation is The values shown are parts by weight. The acetoacetylation degree is calculated, for example, by completely thermally decomposing the resin, trapping a gas of a substance having a β-dicarbonyl structure, that is, acetone in the case of acetoacetylation, with an appropriate solvent, and quantifying the acetone. You.

When the degree of acetoacetylation is low, the crosslinking reaction with the methylol group of the thermosetting resin is not sufficient, and the heat resistance is not much improved. On the other hand, when the degree of acetoacetylation increases,
The flexibility of the polyvinyl acetal resin at room temperature decreases,
Adhesion at room temperature is not much improved.

The polymerization degree of the resin thus obtained is preferably in the range of 1,000 to 3,000, more preferably in the range of 1,700 to 2,500. When the degree of polymerization is low, the heat resistance is not so much improved. on the other hand,
As the degree of polymerization increases, the solubility in organic solvents deteriorates.

Further, as the above resin, an acetoacetalized resin obtained by using acetaldehyde as an aldehyde and a butylacetalized resin obtained by using butyraldehyde are suitably used. Further, an acetoacetal / butyl acetal mixed / acetalized resin obtained by using both acetaldehyde and butyraldehyde is more preferable. The total acetalization degree of these resins is preferably in the range of 50 to 87% by weight. In the case of acetoacetal / butyl acetal mixed acetal resin, the ratio between the degree of acetoacetalization and the degree of butylacetalization is as follows:
A range of 3: 7 to 7: 3 by weight is preferred.

The butyl acetalized resin described above has good adhesiveness and solubility in organic solvents. On the other hand, the acetoacetalized resin is inferior in adhesiveness and solubility but has good heat resistance as compared with the butylacetalized resin. Therefore, the acetoacetal / butyl acetal mixed acetalized resin can appropriately maintain heat resistance, adhesiveness, and solubility.

The degree of acetalization is based on the vinyl acetal in the resin. The values shown are parts by weight. In addition, the above resin is the remaining vinyl alcohol Partial and vinyl acetate With parts. The weight of these vinyl acetal, vinyl alcohol, and vinyl acetate portions can be measured, for example, in accordance with JIS K 6728.

The residual vinyl alcohol portion in the resin is preferably in the range of 15 to 25% by weight. When the residual vinyl alcohol portion is reduced, the adhesiveness is not significantly improved. On the other hand, when the residual vinyl alcohol portion increases, the solubility in the organic solvent deteriorates. Also, the remaining vinyl acetal part is
The smaller the amount, the better the thermal stability, and preferably 3% by weight or less.

In the present invention, as the thermosetting resin having a methylol group, a phenol resin, a melamine resin, a urea resin or the like is suitably used. Such thermosetting resin,
By weight ratio to the polyvinyl acetal resin, 1:
It is preferable to mix at a ratio of 4 to 4: 1, more preferably at a ratio of 2: 3 to 3: 2 by weight.

When the blending ratio of the thermosetting resin is small, the adhesion at normal temperature is good, but the adhesion at high temperature is not so much improved. On the other hand, when the mixing ratio of the thermosetting resin increases, the adhesiveness at a high temperature is good, but the adhesiveness at a normal temperature is not so much improved.

In addition, these thermosetting resins having a methylol group, epoxy resin, thermosetting resin having no methylol group such as urethane resin, other antioxidants, additives such as an antifoaming agent may be appropriately compounded. it can.

Further, in order to form an adhesive composition by blending the polyvinyl acetal resin and the thermosetting resin, both resins are dissolved in an appropriate organic solvent. Examples of the organic solvent include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, and aromatic hydrocarbons such as toluene and xylene, and a single or mixed solvent thereof is used. Thus, the adhesive composition of the present invention is obtained.

(Action) In the adhesive composition of the present invention, the polyvinyl acetal resin has a β-dicarbonyl structure in a side chain, and the methylene group sandwiched between the dicarbonyl groups shows high reactivity.
On the other hand, the thermosetting resin has a methylol group, which is also highly reactive and can cause a condensation reaction.

Therefore, when the adhesive composition is heated, the active methylene group and the reactive methylol group easily react with each other,
Thus, the polyvinyl acetal resin and the thermosetting resin undergo a cross-condensation co-condensation reaction and are cured. Therefore, the heat resistance as an adhesive is remarkably improved.

In addition, the condensation reaction between the active methylene group and the reactive methylol group is effectively performed, and the condensation reaction between the residual hydroxyl group of the polyvinyl acetal resin and the reactive methylol group hardly actually occurs. Therefore, it is presumed that the above-mentioned residual hydroxyl groups are used effectively for bonding to metals such as copper foils and substrates, thereby significantly improving the adhesiveness.

The β-dicarbonyl structure of the polyvinyl acetal resin is liable to form a coordination bond with a metal, and the remaining β-dicarbonyl structure
If there is a dicarbonyl structure, it is presumed that this also contributes to the improvement of the adhesion to metals such as copper foil.

(Examples) Hereinafter, Examples and Comparative Examples of the present invention will be described.

Example 13 1240 g of pure water was placed in the separable flask of Example 3, and an acetoacetylated polyvinyl alcohol resin having a polymerization degree of 1000 and an acetoacetylation degree of 4.5% by weight (Gosefimer ZZ-100, manufactured by Nippon Synthetic Chemical Company) was added thereto. 115 g was added and completely dissolved. The solution is cooled and the concentration is 35% by weight.
87 g of hydrochloric acid and 62 g of butyraldehyde were added and reacted to precipitate and precipitate a resin as a white powder. The reaction solution was neutralized, washed with water, filtered and dried to obtain an acetoacetylated polyvinyl butyl acetal resin. The degree of acetalization of this resin is 69.1
% By weight.

50 g of this acetoacetylated polyvinyl acetal resin
And phenolic resin (BLS-160L, manufactured by Showa Union) 84 g
And epoxy resin (Epicoat 828, Shell Chemical Co., Ltd.) 5g
Was dissolved in 400 g of a mixed solvent of acetone / methyl ethyl ketone / toluene (mixing ratio: 2/2/1) to obtain an adhesive composition.

This adhesive composition is applied to a copper foil for a printed circuit board so as to have a thickness of 35 μm as a solid content, dried at 60 ° C. for 2 minutes, and then dried at 140 ° C. for 2 minutes to obtain a copper foil with an adhesive. Was. Thereafter, the copper foil with the adhesive was superimposed on a phenolic resin-impregnated paper, and heated and pressed at 150 ° C. for 1 hour at 100 kg / cm ² to prepare a printed board.

For the above printed circuit board, according to JIS C 6481,
Solder heat resistance and adhesive strength were measured. Table 1 shows the results. In addition, the solder heat resistance indicates the time until blistering occurs in a 260 ° C. solder bath, and the adhesive strength indicates the peel strength at 20 ° C. and 150 ° C.

Example 2 Except for using acetoacetylated polyvinyl alcohol having a degree of polymerization of 1700 and a degree of acetoacetylation of 8.0% by weight,
Performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 Except for using acetoacetylated polyvinyl alcohol having a degree of polymerization of 2000 and a degree of acetoacetylation of 0.4% by weight,
Performed in the same manner as in Example 1. Table 1 shows the results.

Example 4 Into the separable flask of Example 5, 2600 g of pure water was placed, and 210 g of a polyvinyl alcohol resin having a polymerization degree of 2400 and a residual vinyl acetate portion of 1.5% by weight was added to the flask and completely dissolved. This solution was maintained at 27 ° C., and 480 g of hydrochloric acid having a concentration of 35% by weight and 127 g of acetaldehyde were added thereto and reacted to precipitate and precipitate a white powder resin. The reaction solution was neutralized, washed with water, filtered and dried to obtain a polyvinyl acetoacetal resin. The degree of acetalization of this resin was 73.6% by weight.

140 g of the above polyvinyl acetal resin was put into a glass reactor equipped with a stirrer, heated to 100 ° C. while stirring, and then 10 g of diketene gas was flown into the reactor to react for 1 hour. The resin obtained by this reaction was transferred to a vacuum dryer and degassed at 50 ° C. for 40 hours to remove unreacted diketene gas, thereby obtaining an acetoacetylated polyvinyl acetoacetal resin. The acetoacetylation degree of this resin is 8.9% by weight
Met.

Using this acetoacetylated polyvinyl acetoacetal resin, the subsequent steps were performed in the same manner as in Example 1. Table 1 shows the results.

Example 5 It carried out like Example 4 except using acetaldehyde and butyraldehyde. Table 1 shows the results.

Example 6 A polyvinyl butyl acetal resin having a degree of polymerization of 1700, a degree of acetalization of 71.9% by weight, and a residual vinyl acetate portion of 1.2% by weight was used. Table 1 shows the results.

Example 7 The same operation as in Example 4 was carried out except that 0.65 g of diketene gas was used. Table 1 shows the results.

Example 8 It carried out similarly to Example 4 except having used 20 g of diketene gases. Table 1 shows the results.

Comparative Example The same operation as in Example 5 was performed except that acetoacetylation with diketene gas was not performed. The result is
It is shown in the table.

(Effect of the Invention) Since the adhesive composition of the present invention contains a polyvinyl acetal resin having a β-dicarbonyl structure in a side chain and a thermosetting resin having a methylol group, co-condensation between both resins is prevented. This increases the crosslink density and improves heat resistance. Further, the hydroxyl groups of the polyvinyl acetal resin are effectively used, and the adhesiveness is improved. Further, neither a decrease in electric resistance nor an increase in viscosity of the adhesive composition occurs.

Therefore, the adhesive composition of the present invention can be suitably used for the production of laminated boards requiring heat-resistant adhesion such as printed boards and decorative boards.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C09J 161/20 PHK C09J 161/20 PHK

Claims (1)

(57) [Claims] 1. An adhesive composition comprising a polyvinyl acetal resin having a β-dicarbonyl structure in a side chain and a thermosetting resin having a methylol group.