JPS5917146B2 - glue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive, particularly an improved polyvinyl acetate-9 tar-based adhesive which has excellent heat resistance and is used for printed circuit laminates.

Generally, printed circuit laminates are manufactured by coating steel foil with an adhesive, drying it to form an adhesive-coated steel foil, and heat-pressing the adhesive-coated steel foil with a resin-impregnated base material. These copper-clad laminates are etched to create electrical circuits, and circuit parts are attached to them for use in various electronic devices. : Copper-clad laminates bond metal steel and non-conductive substrates, so of course they require strong adhesive properties, but they also require etching, soldering when attaching circuit components, and especially in recent years. With the trend of immersing products in high-temperature solder baths for long periods of time, products with excellent heat resistance are now required. Therefore, improvements have been made to resin-impregnated base materials and steel plates, but improvements to the adhesive itself are also required. Attempts have been made to improve this type of adhesive by adding new ingredients or improving the blending ratio.

Amino resins such as polyvinyl acetal, phenol resins, epoxy resins, and melamine, and isocyanate resins are used as adhesive components, and among these, polyvinyl acetal is one of the important adhesive components.
0 The present inventors previously made the following proposal regarding the improvement of polyvinyl acetal itself (Japanese Patent Application No. 55-782).
No. 72).

That is, it is an acetoacetal-butyl acetal mixed polyvinyl 5 acetal with a degree of polymerization of 1500 to 2500, in which the weight ratio of the acetoacetal part to the butyl acetal part is 3.7 to 7.23,
It is characterized in that the vinyl alcohol portion is 14 to 21% by weight and the vinyl acetate portion is 3% by weight or less.

0 If such polyvinyl acetal for adhesives is blended with known adhesive components such as phenol resins, amino resins, and epoxy resins, adhesives for printed circuit laminates that provide adhesive strength and soldering heat resistance can be obtained.

A laminate using this adhesive has superior adhesive strength and soldering heat resistance compared to conventional laminates. However, depending on the application, even higher adhesive strength is desired. The present invention aims to solve these drawbacks, and provides a polyvinyl acetal for adhesives whose adhesive strength is further improved by introducing maleic anhydride or maleic acid into the above-mentioned mixed acetal. This is what we are trying to provide.

That is, in the present invention, a modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and maleic acids is used in combination with the raw material polyvinyl alcohol used for acetalization, and this is obtained by acetalizing the polyvinyl alcohol using an acid catalyst. . In the present invention, maleic acids refer to maleic acid, maleic esters, and maleic anhydride.

For example, when using modified polyvinyl alcohol containing 3% by weight of maleic acid, the blending ratio is polyvinyl alcohol/modified polyvinyl alcohol = 5.
It is 0/50 to 95/5, preferably 75/25 to 95/5.

The reason for this limitation is that if the amount of modified polyvinyl alcohol exceeds 50% by weight, there is a limit to its adhesive strength and the solvent solubility after acetalization deteriorates.

Moreover, if it is less than 5% by weight, the adhesive strength is low and it is not practical. In the present invention, the degree of polymerization of polyvinyl alcohol and modified polyvinyl alcohol is 1500 to 25.
00, preferably 1600 to 2500, and 150
If it is less than 0, both adhesiveness and heat resistance are insufficient;
If the adhesive composition exceeds this value, the viscosity of the adhesive composition will be high and the practicality will be poor, and the heat resistance will not increase much.

The copolymer of maleic acids and vinyl acetate used in modified polyvinyl alcohol contains maleic anhydride,
0.5 to 15 mol%, preferably 1 to 5 mol% of one or more of maleic acid and maleic ester? It contains.

Further, a completely saponified product having a degree of saponification of 95 mol% or more is preferable. The polyvinyl acetal of the present invention consists of a vinyl acetal moiety c, a vinyl alcohol moiety d, a vinyl acetate moiety e, and a maleic acid moiety as shown in the following formula, but the vinyl acetate moiety of the polyvinyl acetal is hydrated using a strong alkaline solution. By decomposing and back titrating the remaining alkali with acid, the weight of [ ] 8 parts in the whole sample,
In other words, the vinyl? Le E'2S1 minute is acetylated with a mixture of pyridine and acetic anhydride, and unreacted acetic acid is titrated with an alkali.[]The weight of the d part, that is, the weight of Llld? Calculate and find.

For the maleic acid part, dissolve the sample in pyridine, N/10K
Titrate with 0H isopropyl alcohol solution to determine the weight of the []f portion, i.e., soil Y2? ―、Yo1 and υυn and υυH's weight 7
Calculate it as 0.

The weight of the vinyl acetal part [ ]% is []o-100{[],+[].

+[]f}. Also, the acetoacetal part (
) and the butyl acetal portion ()b are determined by weight using an infrared spectrophotometer.

Further, the smaller the residual vinyl acetate portion is, the better the thermal stability is, and the residual vinyl acetate portion is 3% by weight or less, preferably 2% by weight or less.

Therefore, if a commercially available fully saponified polyvinyl alcohol is used as a raw material, a preferable range of polyvinyl acetals will inevitably be obtained. The polyvinyl acetal of the present invention requires that the weight ratio of the acetoacetal part to the butyl acetal part is 3:7 to 7:3. Generally, polyvinyl butyral is the most commonly used polyvinyl acetal for adhesives, followed by polyvinyl formal. Although polyvinyl formal has better heat resistance than polyvinyl butyral, it is not soluble in general-purpose solvents, and acetoacetal has insufficient adhesiveness and solubility. Mixed acetals using butyraldehyde and acetaldehyde are superior to butyl acetals, but those with a high acetoacetal ratio have poor solvent solubility and a tendency to gel, making them impractical. Those with a high proportion of butyl acetal are insufficient in improving soldering heat resistance. It is not necessary to completely acetalize the vinyl alcohol groups; the remaining hydroxyl groups in the polyvinyl acetal react with the methylol groups in the thermosetting resin such as phenol resin that is blended into the adhesive composition and are cured, so the remaining vinyl alcohol portion If it is less than 14% by weight, there will be a shortage of hydroxyl groups, making it difficult to cure and reducing heat resistance. Furthermore, if the residual vinyl alcohol portion exceeds 21% by weight, the solubility in organic solvents decreases, making it unusable. To produce an adhesive for printed circuit laminates using the polyvinyl acetal of the present invention, known adhesive components such as phenolic resins, amino resins, epoxy resins, isocyanates, and soluble polyurethanes are selected and dissolved in a solvent. Solvents include ketones such as acetone and methyl ethyl ketone, alcohols such as methanol, ethanol, and butanol, and aromatic hydrocarbons such as toluene and xylene, which are matched to the processing conditions and used as a mixed solvent. . Phenol resin is a soluble phenol/formalin resin, and resol type is more common than novolac type.

Also included are modified phenolic resins. In addition, modified melamine resins such as melamine resin, urea resin, methylated melamine resin, and butylated melamine resin are also used as the amino resin. Examples of the epoxy resin include bisphenol type epoxy resin and novolak type epoxy resin. Although there are no particular limitations on the other adhesive components and compounding ratio to be used, a desirable example is 7S as shown below.

{↑-:j=column"""゛"１"": Li[kaji F〒or etc.

Note that an antioxidant and other additives may be appropriately blended as necessary.

The present invention will be specifically explained below with reference to Examples.

Example 1 Production of mixed acetal Add methanol 4009 to a glass flask with a stirrer in 11.
, 3570 hydrochloric acid 59 was charged, and then the degree of polymerization was 2400.
61.59% of completely saponified polyvinyl alcohol and 20.59% of modified polyvinyl alcohol containing 3% by weight of maleic acid with a degree of polymerization of 1650 were added with stirring.

Next, add 30f of acetaldehyde to this! , butyraldehyde (289 g) was added, and the mixture was reacted at a temperature of 60° C. for 6 hours. After the reaction was completed, it was cooled and neutralized by adding 209 g of a 10% aqueous solution of caustic soda.

This was precipitated with water, washed with water and dried.

The product was dissolved in a mixture of ethanol and toluene in a weight ratio of 1:1 to form a 5% solution. Its viscosity is 18 at 20℃
It was 3 cps. Its composition is vinyl acetate 3
．． 4% by weight, vinyl alcohol 16.4% by weight, maleic acid 0.9% by weight, and the ratio of acetoacetal and butyl acetal in the mixed acetal is 50:5 by weight.
It was 0. Manufacture of adhesive The above-mentioned mixed polyvinyl acetal 529, organic solvent {methanol little enlyacetone = 2:2:1 (weight ratio)} 4009, product name of Gunei Chemical Industry Kiki, which is a phenolic resin solution with a solid content of 60% “X
PL-4122B''669 was mixed to prepare an adhesive.

Apply the adhesive obtained in this example to the matte side of the steel foil for 30 minutes.
~359/d (solid content equivalent) was coated and dried at 80°C for 10 minutes and at 150°C for 5 minutes to create an adhesive-coated steel foil.

The coated surfaces of this adhesive-coated steel foil were pressed together at a temperature of 160°C.
Heat-sealing was performed at a pressure of 30 kg/~ and a time of 5 seconds, and the peel strength was measured using a test piece having a width of 20 mm and a length of 50 mm to evaluate adhesiveness. This is shown in Table 1 as Experiment 1.

Example 2 Completely saponified polyvinyl alcohol with a degree of polymerization of 2400 and 3 weights of maleic acid with a degree of polymerization of 1650? A mixed acetal was produced in the same manner as in Example 1, except that the ratio of the modified polyvinyl alcohol contained was changed, and then a test piece for measuring peel strength was prepared.

The relationship between maleic acid content and peel strength is shown in Table 1 for Experiments ▲2 to 4. Example 3 The adhesive-coated side of the adhesive-coated steel foil prepared in Example 1 was placed on several sheets of phenol resin-impregnated paper and heated at 150 to 170°C.
130kg/CT! Steel clad laminates were made by heat-pressing for 1 hour under the conditions of 1, and are shown in Table 2 as Experiments 5 to 8 in which the solder heat resistance and adhesiveness were evaluated.

In addition, soldering heat resistance is 26 according to JISC648l.
The time (Sec) until blistering occurred in a solder bath at 0° C. was measured.

Adhesive strength was measured according to JISC648l. Solution viscosity was measured for a 5% solution using ethanol, toluene 1:1 solvent.

Claims (1)

[Claims] 1 Acetoacetal-butyl acetal mixed polyvinyl acetal with a degree of polymerization of 1500 to 2500, in which the weight ratio of the acetoacetal part to the butyl acetal part is 3:7 to 7:3, and the vinyl alcohol part is 14 to 21. % by weight, vinyl acetate part is 4% by weight or less, maleic acid part is 0.1 to 1.5
Adhesive for printed circuit laminates whose main component is polyvinyl acetal, which is % by weight.