JPS62141077A - Electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition which gives a film having excellent heat resistance and electrical and mechanical characteristics, by neutralizing a mixture of specified amic acid prepolymers, and dispersing it in water. CONSTITUTION:An amic acid prepolymer (A) is obtained by reacting at -30-70 deg.C for 1-10hr 1mol of a carboxylic acid anhydride containing an unsatu rated double bond (e.g., phthalic anhydride) with 1 equivalent of an amino group of an epoxy resin modified with ammonia obtained by the addition reaction at 20-100 deg.C for 1hr - 10 days of ammonia with an epoxy resin in an amount of at least 5mol of ammonia per equivalent of the epoxy group. An amic acid prepolymer (B) is obtained by the addition reaction at 100-130 deg.C for 1-3hr of 1 equivalent of the maleimide group of a bismaleimide compound of the formula (wherein R is a direct board or a divalent linkage) with at least 1 equivalent of the amino group of an aromatic polyamide (e.g., m-pheny lenediamine), and reacting 1 equivalent of an unreacted amino group with 1mol of a carboxylic acid anhydride containing an unsaturated double bond. 30-80% mixture comprising 80-30% component A and 20-70% component B is dis solved in a solvent, neutralized by adding a neutralizing agent, and then dis persed in water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrodeposition paints, and particularly to heat-resistant electrodeposition paints useful for forming coating films having high heat resistance.

[Conventional technology]

In recent years, an electrodeposition coating method for obtaining an organic coating film on a conductor by electrodeposition has attracted attention, and water-soluble electrodeposition varnishes, water-dispersed electrodeposition varnishes, and the like have been developed for this purpose.

Conventionally, polyester resins, polybutadiene resins, acrylic resins, epoxy resins, etc. have been known as these electrodeposited varnishes, but all of these have insufficient heat resistance and the maximum operating temperature is 150°C. There are many things that can be beaten below °C.

[Problem that the invention seeks to solve]

However, in recent years, as electrical equipment has become smaller and lighter, fields that require high heat resistance have expanded, and conventional electrodeposited varnishes are often limited in their range of use.

That is, at present, there are almost no effective electrodeposition varnishes that form a coating film having an imide ring structure and have high heat resistance that can withstand temperatures of 200° C. or higher.

[Means for solving problems]

The present invention aims to overcome these problems (as a result of extensive studies, we have found that the electrodeposition coating composition described below has excellent heat resistance and has relatively well-balanced mechanical and electrical properties. It has been found that a paint film that comes off can be obtained.

That is, an ammonia-modified epoxy resin obtained by adding ammonia to an epoxy resin, an amic acid-containing prepolymer (5) obtained by reacting a carboxylic acid anhydride having an unsaturated double bond, and a bismaleimide compound. After adding an aromatic polyamine, a mixture of the amic acid prepolymer (T3I) obtained by further reacting with an unsaturated double bond-containing carboxylic acid anhydride is neutralized with a neutralizing agent to form a water-dispersed varnish. After electrodepositing on the conductor of the coated object in this varnish, it is subjected to appropriate post-treatment, dried and baked to generate imide rings and at the same time cross-link with unsaturated bonds, resulting in high heat resistance. This provides a strong electrodeposition coating composition.

[Made, for]

The amic acid prepolymer according to the present invention is disclosed in the "electrodeposition coating composition" previously filed by the applicant in Japanese Patent Application No. 68005/1983, and the epoxy resin used in the production of this product is , - The main component is a polyepoxy compound having at least two or more epoxy groups in the molecule, but it is also possible to add a small amount of a monoepoxy compound as long as the gist of the invention is not compromised.

Specifically, bisphenol F type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, polyalkylene ether type epoxy resin, cycloaliphatic epoxy resin, dimer acid type glycidyl ester epoxy resin, epoxidized polybutadiene, etc. Or mix special epoxy resins to give the most favorable results.

Furthermore, an ammonia-modified epoxy resin refers to an epoxy resin containing a primary amine group obtained by adding ammonia to the epoxy group of the epoxy resin, and this compound is obtained by adding an epoxy compound to ammonia or aqueous ammonia.

Here, the reaction between ammonia and epoxy resin is at 20°C.
An epoxy resin dissolved in a similar solvent is added to a solution containing ammonia in aqueous ammonia or a solvent such as alcohol, ketone, or ether at ~100°C for 1 hour to 10 days under normal pressure or under pressure. It is obtained by adding and stirring.

What is important at this time is to prevent the inclusion of secondary or tertiary amine groups in the molecules of the additive product.
For this purpose, it is necessary to react with at least 5 moles or more of ammonia per white amount of epoxy group.

Subsequently, 1 mole of an unsaturated double bond-containing carboxylic acid anhydride is reacted with 1 equivalent of the amino group of the obtained ammonia-modified epoxy compound to produce an amide powder-containing prepolymer.

The unsaturated double bond-containing carboxylic acid anhydride used here refers to a monocarboxylic acid anhydride having a carbon-carbon double bond in the molecule, and specifically includes maleic anhydride, itaconic anhydride, , citraconic anhydride, lyluic acid adduct of maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, dimethylbutyltetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, etc. They can be used alone or in combination without any particular restrictions.

The reaction between the ammonia-modified epoxy resin and the unsaturated double bond-containing carboxylic acid anhydride can be carried out by dissolving the ammonia-modified epoxy resin in a polar solvent such as dimethylformamide, N-methylpyrrolidone, or dimethylacetamide.7. A solution prepared by dissolving 1 mole of an unsaturated double bond-containing carboxylic acid anhydride per equivalent of the primary amino group in the ammonia-modified epoxy resin in the same solvent was gradually added dropwise to this solution while stirring while suppressing heat generation. can be obtained easily.

The reaction temperature at this time is -30'O-70'O, and preferably the reaction is carried out at 0 to 30°C for 1 to 10 hours.

As mentioned above, we have proposed an electrodeposition coating composition based mainly on amic acid prepolymer particles, but if a high molecular weight epoxy resin is used as a raw material to improve electrodeposition efficiency, imide rings will inevitably form. The content tends to decrease and the heat resistance decreases. Therefore, in order to solve these problems, the following amic acid prepolymer (B) of the present invention is mixed.

That is, the bis-silicon compound in the production of the amic acid prepolymer (I) means a direct bond or two bonds expressed by the general formula. The divalent bond may be any group that can bond nitrogen atoms together, such as aliphatic, alicyclic, aromatic, heterocyclic, or a combination thereof, but aromatic groups are particularly preferred. - Specific examples of simalimide are as follows. Although the general formula shown below is the essence, the hydrogen of the maleimide ring may be substituted with a group that does not adversely affect the reaction, such as an alkyl, aryl, halogen, or cyano group. N, N'-ethylene dimaleimide, N, N'-hexamethylene dimaleimide, N
, N'-decamethylene dimaleimide, N,N'-oxydipropylene dimaleimide, ethylenedioxybis(N
-propylmaleimide), N,v-methylene (di1.
4-cyclohexylene) simaleimide, N,N'-isopropylidene (di-1,4-cyclohexylene) simaleimide, 2,6-xylylene simaleimide, 2,5-oxadiazorylene simaleimide, N%N'-paraphenylene (dimethylene) simaleimide, N,N'-2-methylparatoluylene simaleimide, N,N'-thio(diphenylene)dicitraconimide%N%g-methylene(diparaphenylene)bis(chlormaleimide), N,N'
In addition to -hexamethylene bis(cyanmethylmaleimide), particularly preferably N,N'-metaphenylene dimaleimide, N,N'-paraphenylene dimaleimide, N,
N'-oxy(diparaphenylene) simaleimide, N,
N'-methylene (diparaphenylene) simaleimide%N
%Ba-ethylene (diparaphenylene) simaleimide, N
, v-sulfo(diparaphenylene) simaleimide, N,
Examples include N'-metaphenylene bis(paraoxyphenylene) simaleimide.

Specific examples of aromatic polyamines include m-phenylenediamine, p-phenylenediamine, 2,2-bis(4-aminophenyl)propane, benzidine, 4,
4'-diaminodiphenyl sulfide, bis(4-aminophenyl)methylphosphine oxide, bis(4-aminophenyl)phenylphosphine oxide, bis(4-aminophenyl)phenylphosphine oxide, bis(4-aminophenyl)phenylphosphine oxide,
-aminophenyl)methylamine, 1,5-diaminonaphthalene, 1,1-bis(p-aminophenyl)phthalane, 4,4'-diaminobenzophenone, 4,4'-diaminoazobenzene, bis(4-aminophenyl) Phenylmethane, 1.1-bis(4-aminophenyl)cyclohexane, 1.1-bis(4-amino-3-methylphenyl)cyclohexane, 2.5-bis(m-aminophenyl)-1,3,4 -oxadiazole, 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole, 2,5-bis(m-aminophenyl)thiazolo(
4,5-d) Thiazole, 5,5'-di(m-aminophenyl)-(2,2)-bis(1,3,4-oxadiazolyl), 4,4'-bis(p-aminophenyl) -2
, 2-dithiazole, m-bis(4-p-aminophenyl-2-thiazolyl)benzene, 2, z-bis(m-aminophenyl)-5, dibenzimidazole, 4.
4'-Diaminobenzanilide, 4, diaminophenyl benzoate, N%N'-bis(4-aminobenzyl)-p-phenylenediamine and 3,5-bis(m
-7minophenyl)-4-phenyl-1,2,4-triazole. Particularly preferred examples include diamines represented by the general formula, such as 4,4'-diaminodiphenylsulfone, 3,diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, and 4,diaminodiphenyl ether. It is true.

In the reaction between these bismaleimide compounds and aromatic polyamines, at least 1 amino group is reacted with 1 equivalent of maleimide group.
Both are dissolved in a polar solvent such as dimethylformamide, N-methylpyrrolidone, or dimethylacetamide so as to have an equivalent or more, preferably 1.5 to 3 equivalents, and the mixture is heated at 100 to 130'O in a nitrogen gas stream for 1 to 3 hours. Obtained by stirring.

Subsequently, 1 mole of an unsaturated double bond-containing carboxylic acid anhydride is reacted with 1 equivalent of unreacted amino groups, and this can be carried out in the same manner as in the case of the amic acid prepolymer. By the above operations, lyamic acid prepolymer (
Get the smell.

Thus, the mixing ratio of the amic acid prepolymer (5) and the amic acid prepolymer (8) is arbitrary, but if the ratio of the amic acid prepolymer (paddy) exceeds 70%, the stability as a paint will be poor, and the coating will be difficult to use. The membrane tends to become brittle, and
% or less, amic acid prepolymer vinyl.

Since the effect of (g) on crush resistance may be weakened, the amic acid prepolymer (B) Ill.
Select as appropriate between 70%.

The amic acid prepolymer mixture thus obtained can be water-dispersed and is suitable as a stain-receiving composition, particularly as an electrodeposition composition. In order to obtain a suitable water-dispersed varnish, the obtained amic acid-containing prepolymer is dissolved in dimethylformamide.

A prepolymer content of 30 to 80%, preferably 40% in a solvent such as N-methylpyrrolidone or dimethylacetamide.
The resin can be dissolved to a concentrated solution of ~60 g, added with a suitable neutralizing agent to ionize the resin, and then diluted with an appropriate amount of deionized water to produce a suitable water-dispersed varnish. It is.

In neutralizing the amic acid prepolymer, groups such as trimethylamine, triethylamine, N,N'-dimethylethanolamine, N-methylgetanolamine, and triethanolamine are preferably used. The degree of neutralization will vary depending on the resin and requires a sufficient amount of base to disperse the resin.

The composition concentration in water of the water-dispersible varnish thus obtained is preferably 5 to 25% by weight, and the pH of the solution is 5 to 25% by weight.
Electrodeposit paint from a range of 10.

The voltage used when actually electrodepositing the composition according to the present invention can be used in a wide range from 1 to 500 volts, but
A range of ~200 volts is good.

The electrodeposited coating film is dried at a temperature of 100 to 180°C, and then dried at a temperature of 200 to 300°C, preferably 220 to 200°C.
When baking is performed at a temperature of 270°C, an imide ring is formed from the amic acid, and at the same time, it is cross-linked by unsaturated double bonds,
A strong and smooth coating film with excellent heat resistance is formed. below,
The present invention will be explained in detail based on examples.

〔￥　Example〕

First, amide and prepolymer particles were manufactured as follows. A bisphenol A epoxy resin having an epoxy fIi of about 470, Epicor 1001 (trade name, manufactured by Yuka Shell) 470F, was gradually added to 1.51 volume of 25q6 ammonia water (with stirring).

After continuing the reaction at room temperature for 3 days, excess ammonia, water and acetone were distilled out of the system, and the mixture was thoroughly dried under reduced pressure. As a result, an ammonia-modified epoxy resin having an amine value of 11.0 was obtained.

Ammonia-modified epoxy resin 100 synthesized as above
7' was dissolved in 300 ml of dimethylformamide, charged into a reaction vessel, cooled with stirring, and kept at around 5°C.

To this solution, a solution of anhydrous methylnazic [36Jl' and 100 ml of dimethylformamide was added dropwise over 1 hour, and after continued stirring for another 2 hours, the system was heated to 40°C, and about 300 ml of dimethylformamide was added under reduced pressure. was distilled out of the system, and the remaining concentrated solution of amic acid prepolymer in dimethylformamide was poured into a large amount of water with vigorous stirring. The precipitated white powder was collected by filtration, and this powder was further washed with distilled water. Then dry thoroughly. The amide prepolymer (Al) thus obtained had an r shock value of 79.

Next, the production of the amic acid prepolymer (B) will be explained.

That is, N,N'-metaphenylene dimaleimide 10
8P and 4,4'-diaminodiphenylmethane 1191 are dissolved in 300 ml of dimethylformamide, reacted for 2 hours at 105-110°C in a stream of 9 atoms, and then cooled to around 5°C. A solution of 30 J' of maleic anhydride dissolved in 30 ml of dimethylformamide was added dropwise to this solution over 30 minutes, and stirring was continued at room temperature for 2 hours. This solution was then poured into a large amount of water with vigorous stirring to precipitate. A yellow powder was collected by filtration, thoroughly washed with water and dried. The acid value of the amic acid prepolymer thus obtained was 1
In addition, amic acid prepolymer (5),
A method of neutralizing the mixture of both (B) with a neutralizing agent to obtain a water-dispersed varnish will be explained.

Amic acid prepolymer (A) 60J' and amic acid prepolymer (B) 40J produced by the method described above.
' was mixed and dissolved in 100 mj of dimethylformamide, neutralized by addition of triethylamine 12F, and diluted with deionized water to give a non-loose content of 10 mj to obtain a stable water-dispersed varnish. In this water-dispersed varnish, when a degreased copper plate as a test specimen was used as an anode and electrodeposition was applied at 30 volts for 1 minute, the particle layer deposited on the anode had no fluidity and was hard. It belonged to When this test piece was baked at 140°C for 1 hour and then at 270°C for 30 minutes, the resulting coating film was uniform and smooth.

Next, the test results of Examples and Comparative Examples of the present invention are shown in the following table of characteristics of electrodeposition coating films.

In addition, in the comparative example, the amic acid prepolymer (A) 1007' obtained by the above-mentioned manufacturing method was mixed and dissolved in 100 ml of dimethylformamide, and then neutralized by adding 10 P of triethylamine, and the non-volatile content was 10%. Dilute with deionized water to make pH 8.3.

A water-dispersed varnish with an electrical conductivity of 1320 (lr/cm) and 25°C was obtained, and the coating film was created by electrodeposition and baking under the same conditions as in the above-mentioned example, and the test method was also conducted under the same conditions.

In the table above, the acetone resistance refers to the change in the state of the coating film after it is immersed in acetone for 1 hour. Also, T
GA is the temperature at which the coating film was scraped and subjected to a thermogravimetric analyzer to reach a weight of 95% of the initial value, and the temperature was measured in air at a heating rate of 10°O/m rn. In addition, the cross-cut test involves making 100 cuts in the coating film with a size of 1 mm x 1 mm, pasting adhesive tape on top of it, and making 100 cuts in the coating film.
This is to check how many of the particles stick to the tape side.

Thus, even from the characteristic table, the product of the present invention is a comparative example,
In other words, better results were obtained than the conventional coating film made only of amic acid prepolymer.

〔Effect of the invention〕

As explained above, according to the present invention, it has been difficult to obtain a coating film with high heat resistance in the past, but such drawbacks have been solved, and a coating film with excellent heat resistance can be obtained that has excellent electrical and mechanical properties. It has become possible to obtain a product with well-balanced characteristics.

Therefore, the fixing coating composition according to the present invention has high practical utility.

Claims (1)

[Claims] Amic acid prepolymer obtained by reacting an ammonia-modified epoxy resin obtained by adding ammonia to an epoxy resin and an unsaturated double bond-containing carboxylic acid anhydride (
A) is an amic acid prepolymer (B) obtained by adding an aromatic polyamine to a bismaleimide compound and then reacting it with an unsaturated double bond-containing carboxylic acid anhydride.
) is neutralized with a neutralizing agent and dispersed in water.