JPH0346512B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a thermosetting adhesive film with excellent flexibility and heat resistance. [Prior Art] Conventionally, polyimide adhesives used for electrical insulation materials, structural materials, etc. are N, N'-(4,
4-diphenylmethane) bismaleimide and 4,
A precondensate consisting of 4'-diaminodiphenylmethane is known. [Problems to be Solved by the Invention] However, the above-mentioned precondensate itself was hard and brittle and could not be cast into a film. In addition, when used as an adhesive sheet for laminated materials, the solution must be impregnated into a base material such as glass cloth, and then the solvent must be removed to form a prepreg, which is limited by the thickness of the base material, and therefore thin sheets cannot be used. I couldn't get it. The present invention was made in view of the above situation, and it is an object of the present invention to provide a thermosetting adhesive film having excellent flexibility and heat resistance. [Means for solving the problem] That is, the present invention solves the general formula [In the formula, Ar is the formula (a) or formula (b) It has a repeating unit represented by [representing a divalent group] and contains a group of formula (a) and a group of formula (b) in a molar ratio of 10/90 to 50/50. Polyimide (A)
and general formula (In the formula, m is an integer of 2 or more, and R has 2 carbon atoms.
The present invention relates to a thermosetting adhesive film formed by casting a resin composition containing a polymaleimide (B) represented by the above m-valent group. In the present invention, the polyimide (A) is 3,3',4,4'-benzophenonetetracarboxylic dianhydride (hereinafter referred to as BTDA) in a solvent such as cresol or phenol.
) 3,3'-diaminodiphenylsulfone (hereinafter abbreviated as 3,3'-DDS) and 2,4-diaminotoluene (hereinafter abbreviated as 2,4-DAT) obtained by heating and stirring. However, by reacting in an aprotic polar solvent such as dimethylacetamide or dimethylformamide at a temperature below room temperature,
It can also be obtained by synthesizing the corresponding polyamic acid and subjecting it to dehydration and ring closure using a dehydrating agent such as acetic anhydride-polydine. 3,3'-DDS component and 2,4- in polyimide (A)
The molar ratio of DAT components is 10/90 to 50/
Contained at a rate of 50. If the 2,4-DAT component exceeds 90 mol%, the polyimide (A) becomes hard and has poor moldability. Furthermore, if the content of 3,3'-DDS exceeds 50 mol%, film forming properties deteriorate. Polymaleimide (B) that can be used in the present invention
Specific examples include N,N'-(4,4'-diphenylmethane)bismaleimide, N,N'-(4,4'-diphenyloxy)bismaleimide, N,N'-p
-phenylene bismaleimide, N,N'-m-phenylene bismaleimide, N,N'-2,4-tolylene bismaleimide, N,N'-2,6-tolylene bismaleimide, N,N' - ethylene bismaleimide, N,N'-hexamethylene bismaleimide, or There are pomaleimides represented by the following structural formulas, and these can be used alone or in a mixture of two or more. The mixing ratio of polyimide (A) and polymaleimide (B) is 10% of polymaleimide (B) to polyimide (A).
It is preferably used in an amount of ~50% by weight, more preferably 15-30% by weight. Polymaleimide (B) is 10
If it is less than 50% by weight, curing will not be sufficient, and if it exceeds 50% by weight, the resin composition will become brittle and have no moldability. Mixing of polyimide and polymaleimide may be carried out in powder form, but it is usually carried out by adding and dissolving the polymaleimide in a polyimide varnish dissolved in a solvent such as DMF. The thus obtained mixed varnish of polyimide and polymaleimide is cast onto a glass plate, stainless steel plate, etc. and dried to obtain an adhesive film.
The drying temperature and time vary depending on the solvent used and the type of polymerimide, but the temperature needs to be kept lower than the temperature at which the reaction of the polymaleimide becomes noticeable, and the drying time is set so that the amount of residual solvent is about 1% or less. must be done. The obtained adhesive film is laminated on an adherend and then heated and pressed at a temperature above the softening point, thereby making it possible to obtain a molded article with excellent heat resistance and good adhesive strength. Since the adhesive film according to the present invention is highly flexible, it is suitable as an adhesive between a copper foil and a heat-resistant film of a flexible wiring board. The present invention will be explained in detail below with reference to Examples, but the present invention is not limited to these Examples. Example 1 BTDA32.2g, 3,3′-DDS9.9g, 2,4-
7.3 g of DAT was placed in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, and a cooling tube, and 450 g of m-cresol and 108 g of toluene were added thereto, followed by heating and stirring while flowing nitrogen gas. The reaction was carried out at 150 to 160°C for 16 hours to obtain a polyimide varnish with a resin content of 18.2% and a viscosity of 18P. This polyimide varnish was poured into acetone, reprecipitated, crushed, washed and dried to obtain polyimide powder. The reduced viscosity of polyimide powder (concentration 0.1 g/d1, solvent N,N-dimethylformamide (DMF), temperature 30.0°C) is 0.46 dl/
It was hot at g. 100g of the obtained polyimide powder and N,
A varnish was obtained by dissolving 10 g of N'-(4,4'-diphenylmethane) bismaleimide (BMI) in 400 g of DMF. This varnish was cast onto a glass plate and
After drying for 10 minutes at ℃, peel it off, fix it on an iron frame and heat it at 200℃.
After drying for 1 hour, an adhesive film was obtained. The resulting adhesive film had a thickness of 25 μm, a residual solvent content of 1%, a softening point of 260° C., and was excellent in flexibility without cracking even when bent at 180°. Example 2 Example 1 except that 20 g of BMI-M (polymaleimide manufactured by Mitsui Toatsu Chemical Co., Ltd.) was added instead of N,N'-(4,4'-diphenylmethane)bismaleimide.
An adhesive film was obtained in the same manner as above. The obtained adhesive film has a thickness of 25 μm, a residual solvent amount of 1.1%, and a softening point.
It was 220°C and had excellent flexibility without cracking even when bent at 180°. Comparative Example 1 A varnish prepared by dissolving 100 g of Kelimide 601 (polyamino bismaleimide resin manufactured by Nippon Polyimide Co., Ltd.) in 100 g of DMF was cast on a glass plate, and then heated at 130°C for 10 minutes.
I dried it in the oven at 170℃ for 20 minutes, but it was too brittle to form a film. Examples 3 to 5, Comparative Example 2 Adhesive films obtained in the same manner as in Example 1 except that the BMI amount in Example 1 was changed as shown in Table 1.
A copper-clad board was obtained by sandwiching a mm-thick aluminum plate and a 35-μm-thick single-sided roughened copper foil and laminating them at 50 kgf/cm ² at 275° C. for 30 minutes. Table 1 shows the characteristics of the substrate.

〔Effect of the invention〕

As is clear from the above description, the adhesive film of the present invention has excellent film formability, flexibility, and heat resistance, and can be applied to various adhesive applications, and has great industrial value.

Claims (1)

[Claims] 1. General formula [In the formula, Ar is the formula (a) or formula (b) It has a repeating unit represented by [representing a divalent group] and contains a group of formula (a) and a group of formula (b) in a molar ratio of 10/90 to 50/50. Polyimide (A)
and general formula (In the formula, m is an integer of 2 or more, and R has 2 carbon atoms.
A thermosetting adhesive film formed by casting a resin composition containing a polymaleimide (B) represented by the above m-valent group.