JPS59133225A - Heat-resistant coating - Google Patents

Abstract

PURPOSE:To titled coating excellent in covering power and adhesion to substrates and capable of providing coatings of good heat resistance and insulating property, containing a specified polyamic acid. CONSTITUTION:A polyamic acid with a reduced viscosity >=0.5dl/g, containing repeating units of formula I (wherein R1 is R, and R2 is a group of formula IIor III) or containing these units and repeating units of formula IV, is obtained by reacting 1mol of 2,3,5-tricarboxycyclopentylacetic acid (anhydride) obtained by decomposing dicyclopentadiene with ozone and oxidizing the product with 0.5- 1.3mol of a diamine of the formula: H2N-R-NH2 (wherein R is a bivlanet aliphatic, alicyclic, or aromatic group) in a dipolar solvent (e.g., dimethylformamide) at 50-300 deg.C. 100pts.wt. this polyamic acid is mixed with, if necessary, 30- 800pts.wt. conductive filler, pigment, oxidation stabilizer, UV absorber, etc.

Description

[Detailed description of the invention] The present invention relates to a heat-resistant paint.

Polyimide paints have conventionally been known as paints with excellent heat resistance. For example, pyromellitic dianhydride and 4,4
Paints prepared by dissolving aromatic polyamic acid obtained by reacting it with '-diaminodiphenyl ether in a solvent are known.

However, this aromatic polyamic acid paint has poor storage stability in the aromatic polyamic acid solvent, and must be stored at low temperatures because the molecular weight decreases during storage and insoluble matter precipitates. There was a problem with handling the crab.

Conventionally, as conductive paints, there have been known ones in which metal powder such as silver powder or conductive filler such as carbon black is dispersed in a paint made of a polymer substance capable of forming a coating film. However, these conductive paints have drawbacks such as difficulty in obtaining a uniform coating film and reduced adhesion between the resulting coating film and the substrate. As a result of extensive research aimed at improving these shortcomings, we have found that a paint containing polyamic acid with a specific structure has extremely high storage stability, can withstand long-term storage at room temperature, and the resulting paint film does not stick to the substrate. It has excellent coating strength and adhesive strength, as well as heat resistance and insulation properties.Furthermore, by adding a conductive filler to this paint, a conductive paint film can be obtained, and this paint film discovered that the decrease in adhesive strength to the substrate was extremely small, and arrived at the present invention.

The heat-resistant paint of the present invention is characterized in that it contains a polyamic acid obtained by reacting 2,3.5-tricarboxycyclopentyl acetic acid or its anhydride with a diamine. By incorporating a monolithic filler into a coating material containing polyamic acid, a 4-free coating film can be obtained.

The 2,3,5-toIJ carboxycyclopentyl acetic acid (hereinafter referred to as TCA) used in the present invention can be obtained, for example, by ozonolysis of dicyclopentadiene and oxidation with hydrogen peroxide (British Patent No. 872355, J, Or, q-
Chtyn, 28 (10) 2537.1963)
, or by the method of oxidizing hydroxy-dicyclopentadiene obtained by hydrating coventadiene with nitric acid (West German Patent No. 1078120). TCA is an anhydride (usually dianhydride). From the viewpoint of polymerization reaction, it is preferable to use it as

In addition, the diamine to be reacted with TCA or its anhydride is
It is a compound represented by the general formula H2NR-R-NH2 (R is two aliphatic, alicyclic, or aromatic groups).

Preferred R in the above general formula is, for example, i X a X 4 (wherein, Xs
% Xz, Xs, and X4 are the same or different, H is CH3, Y is CH2, C2H4,0,
CH3CFs represents O or 1), such as -(
2 carbon atoms represented by CH □-1 (in the formula, m represents an integer of 2 to 9)
~13 aliphatic or alicyclic hydrocarbon groups are also norbornane derivative hydrocarbon groups, and in order to further improve the heat resistance when the paint of the present invention is imidized by heat treatment, R is an aromatic A group group is preferred.

Specific examples of the diamines mentioned above include nokura phenylene diamine, metaphenylene diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 2,2-di(p-aminophenyl)hexafluoro Propane, 4.4'-diaminodiphenylpropane, benzidine, 4.4'-diaminodiphenyl sulfide, 4.
4'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene,
3.3'-dimethyl-4,4'-diaminobiphenyl,
3.4'-Diaminobenzanilide, 3.4'-diaminodi7' = Yaega 2.2,3-Sia, 7to, Ku7.
2.4. -Diaminotoluene, 3,4-diaminotoluene, 2,6-diaminotoluene, 3.5-diaminotoluene, 2,5-diaminotoluene, 2,4-diaminoanisole, 3,4-diaminoanisole, 2,5- Diaminoanisole, 2゜3-diaminopyridine, 2,5-
Diaminopyridine, 2,6-diaminopyridine, 3.4
-Diaminopyridine, 4,5-diaminopyridine 7.4.
4'-diaminosterpene, metaxylylene diamine,
and baraxylindiamine, 4.4'-methylenebis(7chlorohexylamine), 4.4'-inglobylidenepis(cyclohexyl/ruamiy), 4°4'-oxybis(cyclohexylamine), 4°4'- Sulfone bis(cyclohexylamine), ethylenediamine, propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylene, octamethylenediamine, nonamethylene/diamine,
4.4'-dimethylhbutamethylenediamine, 1.4-
Diaminocyclohexane, 1,3-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanileneshimethylenediamine, tricyclo[6,2
, 1,0''°7]-undecylenedimethyldiami/, etc. These can be used alone or in combination.

The solvent used in the reaction of TCA or its anhydride with diamine or the solvent used in the coating material of the present invention is not particularly limited as long as it dissolves the polyamic acid to be produced1. , e.g. dimethylformamide, dimethylacetamide, N-methyl-
Dipolar polar solvents such as 2-pyrrolidone, dimethylsulfoxide, tetramethylurea, and γ-butyrolactone are used.

Generally, in addition to these high-boiling point solvents, low-boiling point solvents can also be mixed and used within a range in which the polyamic acid does not precipitate. These low boiling point solvents include alcohols, phenols, ketones, and ethers.
i, 4] Eva ethyl alcohol Isopropyl alcohol, phlopylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether phenol, cresol, methyl ethyl ketone, tetrahydrofuran, dioxane and the like.

Although it is preferable to carry out the reaction between TCA or its anhydride and diamine in equimolar amounts, the ratio of these heptamers may be slightly varied as long as the object of the present invention is achieved.

For example, in order to absorb a high molecular weight polyamic acid, it is usually preferable to use about 0.7 to 1.3 moles of diamide/compound per mole of TCA or its anhydride. Furthermore, the molecular weight can be adjusted by adding terminal diamines, dicarboxylic acids, or their anhydrides. The reaction is usually carried out in a solvent, and the amount of solvent is preferably 0.5 to 20 times the weight of TCA or its anhydride and diamine.

The reaction temperature when producing the polyamic acid used in the present invention varies depending on whether TCA or its anhydride is used as a starting material. It is effective to carry out the reaction at a temperature of 50 to 300°C, preferably 100 to 250°C. On the other hand, when TCA anhydride is used as a raw material, it is a heavy cutting edge reaction, and the reaction does not necessarily have to be carried out at a high temperature, and it is usually sufficient to carry out the reaction at a temperature of 0 to 100°C.

The polyamic acid obtained by the above reaction generally has a repeating structural unit represented by the following general formula (I).
It is thought to have a repeating structural unit represented by I) and a repeating structural unit represented by the following general formula (II), (wherein R1 is a divalent aliphatic, alicyclic or aromatic group,
In addition to the above, R2 has the following general formula 0''), ■L'(V) or (V
It is also possible that some repeating structural units represented by I) are present.

The polyamic acid obtained as described above is easily soluble in a solvent, and even if a part of the polyamic acid is imidized, it is soluble in the solvent, so it has excellent stability even in a solution state.

The reduced viscosity of this polyamic acid (concentration xy/100m solvent, solvent dimethylacetamide, measurement temperature 30°C) is
Preferably 09o5cte/g or more, particularly preferably 0
．． 1 to 100 dl/II.

In the present invention, conductive fillers to be mixed into the paint containing the polyamic acid include urine, metal powders such as copper and aluminum, carbon blacks such as Kettien black, acetylene black, and 7-Arnes black, graphite, and the like. used. It is preferable that the form of these conductive fibers is as fine as possible, and when added to the above polyamic acid solution,
It is used after stirring to uniformly disperse it. Conductive paint is
Generally, the volume resistivity of the coating film after formation is 1 Ω under wind control, but this volume resistivity can be adjusted by adjusting the amount of conductive filler added. The amount of conductive filler added depends on the properties of the conductive fins, but polyamic acid 10
It is preferably 30 to 800 parts by weight relative to 0 parts by weight. If the amount added is less than 30 parts by weight, a coating film with excellent conductivity cannot be obtained, and if it is more than 800 parts by weight, the adhesive force to the substrate will be significantly reduced.

When using the paint of the present invention, a paint solution or a paint solution mixed with a conductive filler is usually applied to the substrate, which is the coating surface, and then heat-treated to heat cure it to form a paint film. let

At this time, the polyamic acid is imidized to become polyimide. Before thermal curing, preliminary heating may be performed to remove the solvent and dry the material. Although the imidization temperature depends on the structure of the polyamic acid, it is generally preferably higher than the glass transition temperature of the polyamic acid, and is generally 100 to 500°C.

When the imidization temperature is high, it is preferable to carry out heat curing under a nitrogen atmosphere in order to prevent thermal deterioration of the coating film.

The concentration of polyamic acid in the coating solution is preferably 5 to 80% by weight, particularly preferably 10 to 50% by weight, based on the solvent, but from the viewpoint of ease of handling,
It is desirable to use the polyamic acid solution obtained by the reaction as it is as the coating solution of the present invention.

Depending on the purpose of use, additives such as pigments, oxidation stabilizers, and ultraviolet absorbers may be added to the paint of the present invention. The paint of the present invention can also be used as a separate paint in the form of a powder without being dissolved in a solvent.

Among the paints of the present invention, those without conductive fillers are useful as various coaching coatings for insulated wires, etc., and those with conductive fillers added are made of titanium oxide-based or barium titanate-based substrates. Dielectric ceramic elements such as ceramic capacitors, resistors such as thermistors,
It can be installed on electrodes on glass or other insulating materials, and can also be used for soldering and soldering on electrodes, as a plating base agent, etc.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 8.5 parts by weight of TeA2 anhydride and 7 parts by weight of 4,4'-diaminodiphenyl ether were reacted in 84 parts by weight of dimethylacetamide as a solvent at 25°C for 8 hours to produce the present invention. A polyamic acid solution with a polyamic acid concentration of 16 parts and a reduced viscosity of 2.64 di/g is used as a paint solution. Ta. This solution? After uniform application by spin coating on an aluminum substrate, 170
After drying at ℃ for 20 minutes, it was imidized at 300 ℃ for 1 hour. The coated film tested was a uniform film with no pinholes and -C.

Next, incisions were made in the coating film on this substrate using a cutter to form 5 portions of 2 square base marks.

After applying Shichirono Ntegu to the base plate and performing a peel test, the number of peeled base lines was counted to be 0, indicating that this coating film had excellent adhesion to the substrate. In addition, when the volume resistivity of the coating film was measured, it was 10
It was found that the coating film had a resistance of 16Ω/dark and had excellent electrical insulation properties. Even when the obtained coating solution was stored at room temperature for one month, there was no decrease in solution viscosity and no precipitation of insoluble matter, and it showed extremely excellent storage stability. Further, even when the coating film on the substrate was exposed to 30°C for 10 hours, the number of substrate grains that peeled off in the peel test was O, indicating excellent heat resistance.

Example 2 Using the coating solution obtained in Example 1 and using a copper substrate instead of an aluminum substrate, a coating film was similarly formed on the substrate. The coated film was uniform with no pinholes. When a peeling test was conducted using cellophane tape (same as in Example 1, the same applies hereinafter), the number of peeled base lines was O, indicating that the coating film had extremely good adhesion to the substrate. I understand.

Comparative Example 1 7.4 parts by weight of pyromellitic anhydride and 8.6 parts by weight of 4,4'-diaminodiphenyl ether were polyadded in 84.0 parts by weight of dimethylacetamide as a solvent at 25°C for 8 hours. Polyamic acid concentration 16% by weight,
Coating, drying, and imidization were performed in the same manner as in Example 1 using a polyamic acid solution with a reduced viscosity of 3.25 cu/y. In the peel test of the base grains of the resulting coating film using cellophane tape, the number of base grains that came off was 12, and the adhesiveness could not be said to be good.

Comparative Example 2 A coating film was formed in the same manner as in Example 1 using the polyamic acid solution obtained in Comparative Example 1 and using a copper substrate instead of an aluminum substrate. When a peel test was conducted on the base grains using tape, all the base grains were peeled off, and the adhesion to the substrate was extremely poor.

Example 3 7.6 parts by weight of 4.4'-diaminodiphenylmethane and T
CA2 anhydride 8.8 heavy moieties and dimethylacetamide 8
A polyamic acid solution (polyamic acid concentration 16.4 weight percent, reduced viscosity 4.22 de
/g) was obtained. This solution was applied onto an aluminum substrate in the same manner as in Example 1, and dried and imidized. The formed coating film was uniform with no pinholes. When a peeling test was performed on the base grains using cellophane tape, the number of peeled base grains was zero, indicating that the adhesiveness to the substrate was extremely excellent. Furthermore, when the volume resistivity of the coating film was measured, it was found to be 1016Ω, indicating that the coating film had excellent electrical insulation properties.

Furthermore, even when the obtained coating solution was stored at room temperature for one month, there was no decrease in solution viscosity, no precipitation of insoluble matter, and it showed extremely excellent storage stability. In addition, the coating film on the substrate was heated to 300°C.
Even after being exposed to water for 10 hours, the number of base grains that peeled off in the peel test was 0, indicating excellent heat resistance]7.

Example 4 A copper plate was used as the substrate, and coating was carried out in the same manner as in Example 3, followed by drying and imidization. The coating film formed was uniform and free of pinholes.

When the substrate 1 was subjected to a peel test using Serono Ntegu, the number of substrate grains that were peeled off was 0, indicating that a coating film with excellent adhesion to the substrate had been formed.

Example 5 8.5 parts by weight of TCA2 anhydride and 7.5 parts by weight of 4.4'-diaminodiphenyl ether were reacted at 25°C for 8 hours in 84 parts by weight of dimethylacetamide as a solvent, and a coating solution of the present invention was produced. A certain polyamic acid solution (polyamic acid concentration 16% by weight, reduced viscosity 1.12 dl/g) was obtained. Further, 12.8 parts by weight of silver powder was added to this coating solution, and stirring was continued until it was uniformly dispersed. The obtained suspension was applied onto an aluminum substrate in the same manner as in Example 1, and was dried and imidized.

The resulting coating film was uniform with no pinholes, and a peel test using cellophane tape revealed that the number of peeled base spots was 0, indicating that the coating film had excellent adhesion to the substrate. was forming. Further, when the volume resistivity of the coating film was measured, it was found to be 1-0-'Ω·tan, which is necessary for a coating film with excellent conductivity. Furthermore, even when the obtained coating solution was stored at room temperature for one month, there was no decrease in solution viscosity, no precipitation of insoluble matter, and it showed extremely excellent storage stability. Regarding heat resistance, even when the coating film on the substrate was exposed to 300° C. for 10 hours, the number of substrate lines that peeled off in a peel test was O, indicating excellent heat resistance.

Example 6 10.1 parts by weight of TCA2 anhydride and hexahydro-4,7
- 8.7 parts by weight of methanoin danilene shimethylene diamine, gold, and 81.2 parts by weight of dimethylformamide as a solvent were reacted at 25C for 8 hours to form a polyamic acid solution (polyamic acid concentration) which is the coating solution of the present invention. 18.
8% by weight and a reduced viscosity of 1.28 dl/ji). It was applied onto an aluminum substrate in the same manner as in Example 1, and dried and imidized. The formed coating film was uniform and free of pinholes. When a peel test was performed on the base grains using cellophane cheese, the number of base grains that peeled off was 0, indicating that a coating film with excellent adhesion to the substrate was formed. Further, when the volume resistivity of the coating film was measured, it was found to have good drowsiness insulation at 10'Jicm. Furthermore, even when the obtained coating solution was stored at room temperature for one month, there was no decrease in solution viscosity and no precipitation of insoluble matter, showing extremely excellent storage stability. In addition, the coating film on the substrate was
Even after being exposed to 00°C for 10 hours, the number of base lines that peeled off in the peel test was 0, indicating excellent heat resistance.

As is clear from the above examples, the paint of the present invention has good heat resistance, as well as good wet coverage, peeling resistance, and '! The agent and patent attorney Takeshi Kawakita said that it shows gas insulation properties, and that even those containing a conductive filler show good peeling resistance without deteriorating adhesion.

Claims (1)

[Claims] <1)2,3.5-)! A heat-resistant paint characterized by containing polyamic acid obtained by reacting 7-carpoxycyclobentyl acetic acid or its anhydride with a diamine.