JPH0765028B2 - Heat resistant adhesive - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-resistant adhesive, and particularly to an adhesive excellent in strong adhesive force and heat resistance.

[Conventional technology]

BACKGROUND ART As an adhesive for various high-performance materials used in the fields of electronics, aerospace equipment, transportation equipment, etc., heat-resistant adhesives composed of more organic synthetic polymers have been known than in the past. As excellent ones, polybenzimidazole-based and polyimide-based adhesives have been developed. In addition to the above adhesives, fluororesins,
Polyamide imide, silicone, epoxy novolac,
Adhesives such as epoxy acrylic, nitrile rubber phenol or polyester have been developed, but those that are satisfactory in terms of heat resistance have poor adhesion, and those that have excellent adhesion have heat resistance. It is inferior and is not completely satisfactory. A polyimide adhesive developed by DJ Progar and others as a heat-resistant adhesive with excellent heat resistance and adhesive strength (US Pat. No. 4,065,345) Is only known. However, in order to apply this polyimide as an adhesive, it is necessary to apply it at a considerably high temperature and high pressure, the applicability is improved, and a polyimide having excellent heat resistance, mechanical strength and adhesiveness is required. It was

[Problems to be solved by the invention]

The object of the present invention is applicable to polyimide itself as an adhesive and its applicability is improved, and even when the adhesive force is used at high temperature, during use, it does not decrease after use, heat resistance, and stronger. It is to obtain a novel heat-resistant adhesive having adhesive strength.

[Means for solving problems]

The present inventors have completed the present invention as a result of extensive studies to achieve the above object.

That is, the present invention provides the compound of formula (I) (Where Y is Represents ) Has a repeating unit represented by A group represented by or It is a heat resistant adhesive comprising a polymer film or powder which is a group represented by.

That is, the heat-resistant adhesive of the present invention is 1,3-bis (3-aminophenoxy) benzene (hereinafter abbreviated as APB).
A polyamic acid obtained by polycondensation of 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride (hereinafter abbreviated as BTDA), and a polyimide obtained by further dehydration cyclization. .

The following examples are known as polyimides using APB. One example is a terminal acetylene polyimide oligomer prepared from APB, BTDA and 3-aminophenylacetylene (N. Bilow et al., US Pat. No. 3,845,018 and US Pat.
No. 3,879,349; Thermid-60 manufactured by National Starch & Chem.
(0), when this oligomer is heat-cured, it undergoes addition polymerization due to the terminal acetylene group to obtain a polyimide.

That is, this addition-type polyimide is a polyamic acid oligomer or polyimide oligomer of terminal acetylene, applied as a molding coating or adhesive, and then heated to increase the molecular weight by the reaction of the terminal acetylene group, high molecular weight The modified addition-type polyimide lacks applicability as a molding coating or an adhesive.

Another example is a polycondensation type polyimide consisting of APB and pyromellitic dianhydride (TP Ganet et al., JP 59-170,122).
is there.

The polymer according to the present invention is a polycondensation type polymer obtained by using APB as a diamine component and BTDA as a tetracarboxylic dianhydride component, which is a polymer which is not known at all as a heat resistant adhesive. .

The polymer comprising the combination of APB and BTDA of the present invention is a particularly excellent heat resistant adhesive.

On the other hand, for example, by changing this combination to APB, that is, 1,3-bis (3-phenoxy) benzene, 1,3bis (4-phenoxy) which is the isomer at the substitution position is changed.
The polymers obtained from BTDA using benzene or 1,4-bis (4-aminophenoxy) benzene have extremely low adhesive strength and cannot be used as an adhesive.

Examples of the organic solvent used in this reaction include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-
Diethyl acetamide, N, N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-methylcaprolactam,
1,2-dimethoxyethane, bis (2-methoxyethyl)
Ether, 1,2-bis (2-methoxyethoxy) ethane, bis {2- (2-methoxyethoxy) ethyl} ether, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, pyridine, picoline, dimethylsulfoxide, Examples thereof include dimethyl sulfone, tetramethyl urea, hexamethyl phosphoramide and the like. These organic solvents may be used alone or in combination of two or more.

The reaction temperature is usually 60 ° C or lower, preferably 50 ° C or lower.

The reaction pressure is not particularly limited and can be carried out at normal pressure.

The reaction time varies depending on the type of solvent used and the reaction temperature, and is a time sufficient to complete the production of the polyamic acid represented by the following formula (II), usually 4 to 24 hours.

By such a reaction, the following formula (II) (Where Y is Represents ) Has a repeating unit represented by A group represented by or A polyamic acid which is a group represented by is obtained.

Further, by heating and dehydrating the obtained polyamic acid at 100 to 300 ° C, the following formula (III) (Where Y is Represents ) Has a repeating unit represented by A group represented by or A corresponding polyimide, which is a group represented by, is obtained.

When using the polymer thus obtained as an adhesive, a polyimide film, that is, before being applied to an adherend, a polyimide film obtained by imidizing pomiamic acid, or a solution of a polyamic acid on the adherend. It is applied as a polyimide coating film obtained by coating and imidizing this, or as a manufactured polyimide powder.

Specifically, (1) a method of forming a polyimide coating film on an object to be adhered and adhering a further object to be adhered on the film, that is, mainly using a polyamic acid represented by the above formula (III) as an organic solvent. Solution containing the polyamic acid obtained by reacting APB with tetracarboxylic acid dianhydride in an organic solvent, and a polyamic acid as a main component, which also contains a polyamic acid ring. A solution or suspension containing a part of polyimide containing a polyimide that is a compound is applied to the adherend to be laminated in a thin layer, and then the adhered adherence time in air, 220
Preheated to about ℃ to remove excess solvent, polyamic acid, as a polyimide coating film converted to more stable polyimide, one adherend to this coating film at a pressure of 1 to 1000 kg / cm ² , 50 By pressure-bonding at a temperature of ~ 400 ° C and curing at a temperature of 100-400 ° C, the adherend can be firmly bonded. Further, (2) a method of inserting a polyimide film or powder between the adherends and adhering it, that is, heating and dehydrating the polyamic acid of the above formula (III) to obtain the above formula (IV)
The polyimide represented by the formula, for example, a film made of a polyimide film, or a substantially powdered polyimide powder or the like is inserted between the adherends,
Pressure of 1-1000 kg / cm ² and temperature of 50-400 ℃
Curing at a temperature of ~ 400 ° C can firmly bond the adherend.

The polyimide may contain a part of the polyamic acid of the above formula (III).

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

Example-1 A container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube was charged with 14.6 g (0.05 mol) of APB and 92.1 g of N, N-dimethylacetamide, and at room temperature under a nitrogen atmosphere of 3,3. ′, 4,4′−
Benzophenone tetracarboxylic dianhydride 16.1 g (0.05
Mol) was added in four portions while paying attention to the rise in solution temperature, and the mixture was stirred at room temperature for about 20 hours. Logarithmic viscosity of the polyamic acid thus obtained (N, N-dimethylacetamide solvent, concentration 0.5 g / 100 ml solvent, measured at 35 ° C., the same applies hereinafter)
Was 1.23 dl / g. The polyamic acid solution was cast on a glass plate and then heated at 100 ° C., 200 ° C. and 300 ° C. for 1 hour to obtain a pale yellow transparent polyimide film. The glass transition temperature of this polyimide film is 197 ° C.
(By TMA penetration method. The same applies below.) 5% thermal decomposition temperature is 5
It was 39 ° C. (according to DTA-TG. The same applies hereinafter). Insert this polyimide film between cold-rolled steel sheets (JIS G3141, SPCC / SD, 25 x 100 x 1.6 mm) preheated to 130 ° C,
The pressure was applied to 20 kg / cm ² at 340 ° C. for 5 minutes for pressure bonding.

The tensile shear bond strength of this product at room temperature was 310 kg / cm ² , and when it was further measured at a high temperature of 180 ° C, it was 205
It was kg / cm ² . (The measuring method is based on JIS-K6848 and 6850. The same applies to the following.) Example-2 Under a nitrogen atmosphere, 14.6 g (0.05 mol) of APB was added to 92.1 g of bis (2-methoxyethyl) ether and stirred. Meanwhile, 15.8 g (0.049 mol) of 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride was added in small portions until the dry solid was added. During this time, cool the reactor so that the temperature remains at 25 to 30 ° C, add 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, and stir at room temperature in a nitrogen atmosphere for about 20 hours. It was The polyamic acid thus obtained had an inherent viscosity of 0.73 dl / g.

The above polyamic acid adhesive solution was applied to a cold-rolled steel sheet washed with trichloroethylene (the same as above), and dried by heating at 100 ° C for 1 hour and 220 ° C for 1 hour, and then cold-rolled steel sheets were overlaid at 300 ° C. Pressure was applied to 20 kg / cm ² for 5 minutes for pressure bonding.

The applied adhesive thickness was 30 microns. The tensile shear bond strength of this product was 277 kg / cm ² at room temperature. When this was further measured at a high temperature of 200 ° C, it was 155 kg.
It was / cm ² .

Comparative Example-1 The same operation as in Example-1 except that APB in Example-1, that is, 1,3-bis (3-aminophenoxy) benzene was replaced by 1,4-bis (4-aminophenoxy) benzene. Thus, a polyamic acid having an inherent viscosity of 1.23 dl / g was obtained. After casting this polyamic acid solution on a glass plate,
A polyimide film was obtained by heating at 0 ° C., 200 ° C. and 300 ° C. for 1 hour each. The glass transition temperature of this polyimide film was 446 ° C, and the 5% thermal decomposition temperature was 500 ° C. Using this polyimide film, a cold rolled steel plate was pressure bonded under the same conditions as in Example-1. The tensile shear bond strength of this product at room temperature was 0 kg / cm ² .

Comparative Example-2 A polyamic acid having a logarithmic viscosity of 1.06 dl / g was obtained by the same procedure as in Example-1, except that APB in Example-1 was replaced with 1,3bis (4-aminophenoxy) benzene. . After casting this polyamic acid solution on a glass plate, 100
A polyimide film was obtained by heating each at 1 ° C, 200 ° C and 300 ° C for 1 hour. The glass transition temperature of this polyimide film was 320 ° C, and the 5% thermal decomposition temperature was 514 ° C. Using this polyimide film, a cold rolled steel plate was pressure bonded under the same conditions as in Example-1. The tensile shear adhesive strength of this product at room temperature was 110 kg / cm ² .

Comparative Example 3 APB was 14.0 g (0.048 mol) and 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride was 16.1 g (0.050 mol).
Other than that was used and the same operation as in Example 2 to obtain a polyamic acid. 0.5 g (0.004 mol) of 5-aminophenylacetylene was further added to this polyamic acid, and the mixture was stirred for 3 hours to react with the terminal. Using the solution of the polyamic acid thus obtained, cold-rolled steel sheets were pressure bonded under the same conditions as in Example 2. The tensile shear strength of this product at room temperature is 180 kg / cm
² and 160 kg / cm ² at 180 ° C. Thus, the one having an acetylene group at the end had a poor adhesive strength at room temperature.

〔The invention's effect〕

The present invention provides a novel heat-resistant adhesive that exhibits a strong adhesive force without lowering the heat resistance and can maintain a high adhesive force even at high temperatures.

Claims (1)

[Claims] 1. A formula (I) (Where Y is Represents ) Has a repeating unit represented by A group represented by or A heat-resistant adhesive composed of a polymer film or powder which is a group represented by.