JP3034137B2 - Heat resistant adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant adhesive, and more particularly to an adhesive having strong adhesive strength and extremely excellent heat resistance.

[0002]

2. Description of the Related Art Conventionally, adhesives composed of various organic synthetic polymers have been known. Among them, adhesives such as polybenzimidazole and polyimide have been developed as those having excellent heat resistance. ing. Particularly, as adhesives for polyimide-based films which are heat-resistant films, in addition to the above-mentioned adhesives, adhesives such as fluororesins, polyamideimide, silicone, epoxy novolak, epoxyacrylic, nitrile rubber phenol or polyester-based adhesives have been developed. However, those which are satisfactory in terms of heat resistance have poor adhesive strength, and those having excellent adhesive strength are not sufficiently satisfactory such as having poor heat resistance. As a heat-resistant adhesive, those having both excellent heat resistance and adhesive strength are described in D.A. J. A polyimide adhesive developed by Progar et al. (U.S. Pat. No. 4,065,345) and a polyimide adhesive developed by the present inventors (JP-A-61-345)
143377, 143478, 291669, 2
No. 91670). Some of these have excellent tensile shear adhesive strength of the adhesive at room temperature and high temperature, but their peel adhesive strength is not satisfactory.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-resistant material that does not decrease not only in the tensile shear strength of an adhesive during and after use, but also in the peel adhesive strength even when used at a high temperature. An object of the present invention is to obtain a novel heat-resistant adhesive having strong adhesive strength.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and by blending a specific bismaleimide compound with a polyamic acid having a specific structure, a strong adhesive force has been obtained. It has been found that a heat-resistant adhesive having the same can be obtained, and the present invention has been completed. That is,
The heat-resistant adhesive of the present invention comprises a diamine compound represented by the following general formula (1):

[0005]

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[Wherein X ₁ is directly connected, and has 1 to 10 carbon atoms.
And a group selected from the group consisting of a divalent hydrocarbon group, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group and an oxide. 10 to 50 mol% of the aromatic diamine compound (A) represented by the general formula (2)

[0007]

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[Wherein X ₂ is directly linked, and has 1 to 10 carbon atoms.
And a group selected from the group consisting of a divalent hydrocarbon group, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group and an oxide. And the aromatic diamine compound (B) represented by the general formula (3)

[0009]

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[Wherein Y is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group connected directly or by a crosslinking member. A tetravalent group selected from the group consisting of non-fused polycyclic aromatic groups. 100 parts by weight of a polyamic acid obtained by polymerizing a tetracarboxylic dianhydride represented by the following formula (1) with an organic solvent, and the general formula (4):

[0011]

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[Wherein R is

[0013]

Embedded image Z represents a direct bond or having 1 to 1 carbon atoms.
0 represents a group selected from the group consisting of a divalent hydrocarbon group, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group and an oxide. ] The bismaleimide compound represented by the formula (1) is not less than 0.1 part by weight and less than 5 parts by weight.

The diamine compound (A) represented by the general formula (1) (Formula 6) used as a raw material of the heat-resistant adhesive of the present invention includes bis [4- (3-aminophenoxy)
Phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3
-Aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane,
2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane , 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy)
Phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4- (3-
Aminophenoxy) phenyl] sulfone, bis [4-
(3-aminophenoxy) phenyl] ether and the like, and these may be used alone or as a mixture of two or more.

Examples of the diamine compound (B) represented by the general formula (2) (Formula 7) include, for example, 2,3-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether,
Diaminodiphenyl ethers represented by 4,4'-diaminodiphenyl ether, represented by bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfide, and bis (4-aminophenyl) sulfide Diaminodiphenyl sulfides, bis (3-aminophenyl) sulfoxide, (3-
Diaminodiphenylsulfoxides represented by aminophenyl) (4-aminophenyl) sulfoxide, bis (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) (4
Diaminodiphenylsulfones represented by -aminophenyl) sulfone and bis (4-aminophenyl) sulfone, represented by 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, and 4,4'-diaminobenzophenone Diaminobenzophenones, 3,3 '
Diaminodiphenylalkanes represented by -diaminodiphenylmethane, 3,4'-diaminodiphenylmethane and 4,4'-diaminodiphenylmethane; 2,2-bis (3-aminophenyl) -1,1,1,3,3 3-
Diaminodiphenylhexafluoropropanes represented by hexafluoropropane, 2,3-diaminobiphenyl, 3,3′-diaminobiphenyl, 3,4 ′
And diaminobiphenyls represented by -diaminobiphenyl, and these are used alone or in combination of two or more.

Further, the tetracarboxylic dianhydride represented by the general formula (3) (formula 8) of the present invention includes, for example, ethanetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic acid Dianhydride,
3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride,
2,2'-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane Dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, bis (3,4-dicarboxyphenyl) ether Anhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, 1, 1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride,
Bis (3,4-dicarboxyphenyl) methane dianhydride, 4,4 ′-(p-phenylenedioxy) diphthalic dianhydride, 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, pyro Meric acid dianhydride, 1,
2,3,4-benzenetetracarboxylic dianhydride, 3,
4,9,10-perylenetetracarboxylic dianhydride,
Examples thereof include 2,3,6,7-anthracenetetracarboxylic dianhydride and 1,2,7,8-phenanthrenetetracarboxylic dianhydride. These may be used alone or in combination of two or more.

In the present invention, even if a polyamic acid is partially contained in the polyamic acid solution or the obtained polyamic acid powder by dehydration and ring closure of the polyamic acid, the effect of the present invention is not impaired. Anything is fine.

In the present invention, the organic solvent used for reacting the tetracarboxylic dianhydride with the diamine compound includes N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methyl-2-pyrrolidone,
Amides represented by methylcaprolactam, tetrahydrofuran, 1,4-dioxane, ethers represented by diethylene glycol dimethyl ether, pyridine, pyridines represented by γ-picoline, phenol, m-cresol, o-chlorophenol; Typical examples include phenols, sulfoxides represented by dimethylsulfoxide and diphenylsulfoxide, and sulfones represented by dimethylsulfone and diphenylsulfone. These may be used alone or in combination.

The reaction temperature for obtaining the polyamic acid solution is as follows:
It is usually 10 to 100 ° C, preferably 30 to 80 ° C.
If the reaction temperature is too low, it takes time to reach a desired degree of polymerization, which is not practical. On the other hand, if the reaction temperature is too high, imidization proceeds too much, and a solution having good storage stability cannot be obtained.

The reaction pressure for obtaining the polyamic acid solution is not particularly limited, and the reaction can be sufficiently carried out at normal pressure. The reaction time varies depending on the solvent used for the reaction and the reaction temperature, but the reaction is carried out until the polyamic acid is completely formed and the desired degree of polymerization is reached. Usually, 30 minutes to 10 hours are sufficient.

The synthesis of polyamic acid is generally carried out by dissolving a diamine compound in an organic solvent and adding tetracarboxylic dianhydride (US Pat.
No. 065345).

The diamine compound (A) represented by the general formula (1) (formula 6) used in the present invention and the diamine compound (formula 2) (formula 7)
As for the ratio with the diamine compound (B), the former is usually used in the range of 10 to 50 mol%, preferably 20 to 40 mol%. When the proportion of the diamine compound (A) exceeds 50 mol%, the adhesive strength at high temperature of the adhesive decreases, and when the proportion of the diamine compound (A) is less than 10 mol%, the adhesive strength of the adhesive decreases. The effect of the present invention cannot be obtained.

Examples of the bismaleimide compound represented by the general formula (4) (formula 9) to be used by being blended with the polyamic acid in the present invention include 1,3-bis (3-maleimidophenoxy) benzene and bis [4 -(3-maleimidophenoxy) phenyl] methane, 1,1-bis [4- (3-maleimidophenoxy) phenyl] ethane, 1,2-bis [4- (3-maleimidophenoxy) phenyl] ethane, 2,2 -Bis [4- (3-maleimidophenoxy)
Phenyl] propane, 2,2-bis [4- (3-maleimidophenoxy) phenyl] butane, 2,2-bis [4
-(3-maleimidophenoxy) phenyl] -1,1,
1,3,3,3-hexafluoropropane, 4,4'-
Bis (3-maleimidophenoxy) biphenyl, bis [4- (3-maleimidophenoxy) phenyl] ketone, bis [4- (3-maleimidophenoxy) phenyl] sulfide, bis [4- (3-maleimidophenoxy) phenyl] sulfone And bis [4- (3-maleimidophenoxy) phenyl] ether and the like, which may be used alone or as a mixture of two or more.

These bismaleimide compounds can be produced by subjecting the corresponding diamine compound and maleic anhydride to condensation and dehydration reactions, for example, by the method described in JP-A-4-99764.

The mixing ratio of the bismaleimide compound to the polyamic acid is 0.1 to 100 parts by weight of the polyamic acid.
It can be used in an amount of not less than 5 parts by weight, preferably not less than 1 part by weight and not more than 3 parts by weight. If the amount of the bismaleimide compound is less than 0.1 part by weight, there is no effect on the improvement of the adhesive strength intended in the present invention, and if it is 5 parts by weight or more, the adhesive strength tends to decrease, which is not preferable.

The method of mixing the bismaleimide compound with the polyamic acid is generally to add and dissolve the bismaleimide compound in a polyamic acid solution obtained by polymerizing a diamine compound and tetracarboxylic dianhydride in an organic solvent. However, it is also possible to add during polymerization, for example, when charging a diamine compound or a tetracarboxylic anhydride, or during the polymerization.

Further, for example, a polyamide acid varnish is
Mix with poor solvent such as alcohol to precipitate amic acid powder,
It is also possible to mix the bismaleimide compound and the solid after isolation by a method of drying, or to prepare a polyamic acid solution in which a bismaleimide compound is added and dissolved in advance and mix with the above poor solvent, or a solvent. A powder or a film can be obtained by a method of evaporating water.

When the thus obtained bismaleimide compound of the present invention is blended with a polyamic acid as an adhesive, the polyamic acid is heated and dehydrated by imidization to be used. For example, when used as a solution of an organic solvent or the like used for the polymerization of polyamic acid, the above solution is applied to an adherend to be bonded, and then heated at normal pressure or reduced pressure, and at a higher temperature after removing the solvent. The object to be bonded can be firmly bonded by pressure bonding.
Alternatively, the object to be adhered can be firmly adhered by inserting a film-like or powdery material in advance between the objects to be adhered by heating and desolvating the polyamic acid solution between the adherends, and then pressing the adherend at a high temperature.

[0029]

The present invention will be described below in more detail with reference to examples and comparative examples. Synthesis Example 1 In a glass reactor equipped with a reflux condenser, a nitrogen inlet, a thermometer and a stirrer, 92 g (0.25 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 4,4'- 150 g (0.75 mol) of diaminodiphenyl ether and 1832 g of N, N-dimethylacetamide were charged and 3 g
The temperature was raised to 0 ° C. to dissolve the diamine. 216 g (0.99 mol) of pyromellitic dianhydride under a nitrogen atmosphere
Was added over 3 hours while maintaining the temperature at 30 ° C., and stirring was further continued at 60 ° C. for 3 hours. The solution viscosity at that time is 1
It was 5,000 centipoise (measured with an E-type viscometer manufactured by Tokyo Keiki, 25 ° C., the same applies hereinafter).

Example 1 The 20% by weight polyamic acid solution 50 obtained in Synthesis Example 1
To 0 g, 3.0 g of 4,4'-bis (3-maleimidophenoxy) biphenyl (3.0 parts by weight with respect to 100 parts by weight of polyamic acid) was added, and the mixture was stirred at room temperature for 4 hours to dissolve. Using the solution thus obtained, cold-rolled steel was bonded, and the bonding strength was measured. First, the above solution is applied to each side of the steel sheet to be bonded, and dried at 150 ° C. for 1 hour under reduced pressure.
Heating was performed at 40 ° C. under a pressure of 50 kg / cm ² for 5 minutes, and the tensile shear adhesive strength was measured according to the method of JIS K6850, and the T-shaped peel adhesive strength was measured according to the method of JIS K6854. The adhesion test piece is
The adhesive surface of the cold rolled steel of JIS G3141 (SPCC-SD) was degreased with acetone before use. The measurement was performed at 23 ° C. and 250 ° C., and the results are shown in Table 1 (Table 1).

Comparative Example 1 Adhesion was carried out in exactly the same manner as in Example 1 except that the polyamic acid solution obtained in Synthesis Example 1 was used as it was, and the shear strength of the adhesive at 23 ° C. and 250 ° C. Table 1 (Table 1) together with the results of measuring the shape peel adhesion strength
It described in.

Comparative Example 2 The 20% by weight polyamic acid solution 50 obtained in Synthesis Example 1
To 0 g, 7.0 g of 4,4'-bis (3-maleimidophenoxy) biphenyl (7.0 parts by weight based on 100 parts by weight of polyamic acid) was added, and stirring was continued at room temperature for 4 hours to dissolve. Using the solution thus obtained, bonding was performed in exactly the same manner as in Example 1, and the temperature of the bonded product was measured at 23 ° C and 2 ° C.
The results obtained by measuring the tensile shear adhesive strength at 50 ° C. and the T-shaped peel adhesive strength are shown in Table 1 (Table 1).

Synthesis Example 2 29 g (0.08 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 4,4'-bis (3-aminophenoxy) biphenyl were placed in a glass reactor equipped with a reflux condenser, a nitrogen inlet, a thermometer and a stirrer. 184 g (0.92 mol) of 4'-diaminodiphenyl ether and 852 g of N, N-dimethylacetamide were charged, and 30
The temperature was raised to ° C. to dissolve the diamine. Under a nitrogen atmosphere, 216 g (0.99 mol) of pyromellitic dianhydride was added over 3 hours while maintaining the temperature at 30 ° C., and stirring was continued at 60 ° C. for 3 hours. The solution viscosity at that time is 2
It was 3,000 centipoise.

Comparative Example 3 The 20% by weight polyamic acid solution 50 obtained in Synthesis Example 2
To 0 g, 3.0 g of 4,4'-bis (3-maleimidophenoxy) biphenyl (3.0 parts by weight with respect to 100 parts by weight of polyamic acid) was added, and the mixture was stirred at room temperature for 4 hours to dissolve. Using the solution thus obtained, bonding was performed in exactly the same manner as in Example 1, and the temperature of the bonded product was measured at 23 ° C and 2 ° C.
The results obtained by measuring the tensile shear adhesive strength at 50 ° C. and the T-shaped peel adhesive strength are shown in Table 1 (Table 1).

Synthesis Example 3 203 g (0.55 mol) of 4,4′-bis (3-aminophenoxy) biphenyl and 4,4′-bis (3-aminophenoxy) biphenyl were placed in a glass reactor equipped with a reflux condenser, a nitrogen inlet, a thermometer and a stirrer. 4'-
90 g (0.45 mol) of diaminodiphenyl ether and 1172 g of N, N-dimethylacetamide were charged and 3 g
The temperature was raised to 0 ° C. to dissolve the diamine. 216 g (0.99 mol) of pyromellitic dianhydride under a nitrogen atmosphere
Was added over 3 hours while maintaining the temperature at 30 ° C., and stirring was further continued at 60 ° C. for 3 hours. The solution viscosity at that time is 1
It was 1,000 centipoise.

Comparative Example 4 The 20% by weight polyamic acid solution 50 obtained in Synthesis Example 3
To 0 g, 3.0 g of 4,4'-bis (3-maleimidophenoxy) biphenyl (3.0 parts by weight with respect to 100 parts by weight of polyamic acid) was added, and the mixture was stirred at room temperature for 4 hours to dissolve. Using the solution thus obtained, bonding was performed in exactly the same manner as in Example 1, and the temperature of the bonded product was measured at 23 ° C and 2 ° C.
The results obtained by measuring the tensile shear adhesive strength at 50 ° C. and the T-shaped peel adhesive strength are shown in Table 1 (Table 1).

Synthesis Example 4 147 g (0.40 mol) of 4,4′-bis (3-aminophenoxy) biphenyl and 4,4′-bis (3-aminophenoxy) biphenyl were placed in a glass reactor equipped with a reflux condenser, a nitrogen inlet, a thermometer and a stirrer. 4'-
120 g (0.60 mol) of diaminodiphenyl ether
And 1932 g of N-methylpyrrolidone, and the temperature was raised to 40 ° C. to dissolve the diamine. Under a nitrogen atmosphere, 216 g (0.99 mol) of pyromellitic dianhydride was added to 40
Over a period of 3 hours while maintaining the temperature at
Stirring was continued at 2 ° C. for 2 hours. The solution viscosity at that time was 43,0
It was 00 centipoise.

Example 2 The 20% by weight polyamic acid solution 50 obtained in Synthesis Example 4
To 0 g, 1.5 g of 4,4'-bis (3-maleimidophenoxy) biphenyl (1.5 parts by weight based on 100 parts by weight of polyamic acid) was added, and stirring was continued at room temperature for 4 hours to dissolve. The solution thus obtained was cast on a glass plate and dried under reduced pressure at 160 ° C. for 2 hours to obtain a 30 μm thick film. This film was inserted between the cold-rolled steel sheets used in Example 1, and heated and pressed at 340 ° C. under a pressure of 50 kg / cm ² for 5 minutes. The results obtained by measuring the tensile shear adhesive strength and the T-peel adhesive strength at 23 ° C. and 250 ° C. of the adhesive material in the same manner as in Example 1 were combined with the first result.
It was described in the table (Table 1).

[0039]

[Table 1]

[0040]

As is evident from the results shown in Table 1 (Table 1), the polyamic acid containing the bismaleimide compound of the present invention has a T-shape as well as a tensile shear adhesive strength of an adhesive at a high temperature. High adhesive strength can be obtained even in peel adhesive strength, and it is useful as a novel heat-resistant adhesive.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-205474 (JP, A) JP-A-62-235382 (JP, A) JP-A-62-235383 (JP, A) JP-A-2- 138788 (JP, A) JP-A-61-143478 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 179/08 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A diamine compound represented by the following general formula (1): [In the formula, X ₁ is a group consisting of a direct bond, a divalent hydrocarbon group having 1 to 10 carbon atoms, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group or an oxide. Shows selected groups. Aromatic diamine compound (A) represented by the formula:
0 mol% and the general formula (2) [Wherein X ₂ is a group consisting of a direct bond, a divalent hydrocarbon group having 1 to 10 carbon atoms, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group or an oxide. Shows selected groups. Aromatic diamine compound (B) 50 to 9
0 mol% is represented by the general formula (3). [Wherein, Y is an aliphatic group having 2 or more carbon atoms, a cycloaliphatic group,
And a tetravalent group selected from the group consisting of a monocyclic aromatic group, a condensed polycyclic aromatic group, and a non-condensed polycyclic aromatic group in which aromatics are connected to each other directly or by a bridge member. 100 parts by weight of a polyamic acid obtained by polymerizing a tetracarboxylic acid dianhydride represented by the formula (I) with an organic solvent, and a general formula (4). [Wherein R is Z represents a direct bond or having 1 to 1 carbon atoms.
0 represents a group selected from the group consisting of a divalent hydrocarbon group, a hexafluorinated isopropylidene group, a carbonyl group, a thio group, a sulfinyl group, a sulfoxide group, a sulfonyl group and an oxide. ] A heat-resistant adhesive comprising at least 0.1 part by weight and less than 5 parts by weight of a bismaleimide compound represented by the formula: