JPH0328464B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrical insulating paint and a method for producing the same, and in particular to a highly concentrated polyesteramide resin electrical insulating paint that can reduce the use of organic solvents and a method for producing the same. The present invention relates to an achievable polyesteramide resin electrical insulation coating and a method for producing the same. Conventional electrical insulating paints (hereinafter simply referred to as insulating paints) are mainly made by dissolving film-forming resins such as polyester resins and polyesterimide resins in organic solvents mainly consisting of cresol solvents such as cresol and phenol. However, the film-forming resin content in these insulating paints is at most 20 to 40%.
Stay at %. From the viewpoints of resource conservation, work environment improvement, and pollution prevention, it is desirable to reduce the amount of organic solvents that make up the remaining 60 to 80%, and there has been a demand for the development of high-concentration insulating paints. Furthermore, the above-mentioned cresol solvents have problems in terms of odor and toxicity, and it has been desired to develop an insulating coating that does not use cresol solvents. The present inventors have conducted intensive studies to meet the above requirements, and as a result have arrived at the present invention, which will be described below. By utilizing the shape of the insulating paint, we succeeded in obtaining an insulating paint that not only maintains good properties as a heat-resistant insulating paint, but also achieves high concentration and is soluble in non-cresol solvents. That is, the insulating paint of the present invention contains organic polycarboxylic acids selected from the group consisting of organic polycarboxylic acids, organic polycarboxylic acid anhydrides, and organic polycarboxylic acid lower alkyl esters, an organic polyhydric alcohol, and citric acid. It is characterized by consisting of a polyesteramide resin obtained by reacting with an organic diamine and an organic solvent. Examples of the organic polycarboxylic acids used in the present invention include succinic acid, adipic acid, sebacic acid,
Examples include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, butanetricarboxylic acid, hemimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid, naphthalene dicarboxylic acid, and the like. Furthermore, anhydrides and lower alkyl esters of these acids can also be used as the organic polycarboxylic acids in the present invention. One type of these organic polycarboxylic acids may be used, or two or more types may be used in combination as appropriate. Examples of the organic polyhydric alcohol used in the present invention include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, neopentylene glycol, butanediol, glycerin, trimethylolpropane, tris( Examples include 2-hydroxyethyl) isocyanurate and pentaerythritol. One type of these organic polyhydric alcohols may be used, or two or more types may be used in combination. As mentioned above, the citric acid used in the present invention is an oxytricarboxylic acid having one hydroxyl group and three carboxyl groups in the molecule, but usually contains 1 hydroxyl group and 3 carboxyl groups in the molecule.
It is often commercially available as a crystal with a molecular weight of 210. In the present invention, both citric acid not containing water of crystallization and citric acid containing water of crystallization can be used. Examples of the organic diamine used in the present invention include hexamethylene diamine, octamethylene diamine, metaphenylene diamine, paraphenylene diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,
Examples include 4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylpropane, metaxylene diamine, paraxylene diamine, 1,4-diaminocyclohexane, 2,2'-diaminodiethyl ether, and guanamine. One type of these organic diamines may be used, or two or more types may be used in combination as appropriate. As the organic solvent used in the present invention, it is preferable to use a non-cresol solvent. The insulating coating of the present invention is soluble in non-cresol solvents. Examples of the cresol solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether,
Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, 3-methylmethoxybutanol, 2,3,4-trimethyl 1,3-pentanediol monoisobutyrate,
Examples include glycol ether solvents such as ethylene glycol monoisobutyl ether, alcohol solvents such as benzyl alcohol, acetone alcohol, and diacetone alcohol, and isophorone. Among these, the general formula R ₁ O (CHR ₂ −
Glycol ether solvents represented by CH ₂ O) _o (R ₁ is a lower alkyl group, R ₂ is hydrogen or a methyl group, n is an integer of 1 to 3) are particularly suitable. These are 1
Seeds may be used, but two or more types are usually used in combination.
Further, an aromatic hydrocarbon solvent such as xylene may be used in combination as long as it does not cause turbidity. However, in the present invention, gresol solvents such as cresol, phenol, and xylenol may be used as the organic solvent. This is because even if these cresol solvents are used, the amount of organic solvent used can be reduced according to the present invention, and an insulating coating with high concentration can be obtained. Although one type of cresol solvent may be used, a mixed solvent of two or more types is usually used. Also in this case, an aromatic hydrocarbon solvent such as xylene may be used in combination within a range that does not cause turbidity. It is preferable to add a crosslinking agent to the electrically insulating paint of the present invention as appropriate from the viewpoint of improving the performance of the paint film. Specific examples of crosslinking agents include tetrabutyl titanate, tetraisopropyl titanate,
Examples include tetraphenyl titanate, or organic titanium compounds obtained by chelating these compounds with triethanolamine, ethyl acetoacetate, acetylacetone, or the like. The polyesteramide resin according to the present invention is not particularly limited in its production method, but is preferably selected from the group consisting of organic polycarboxylic acids, organic polycarboxylic acid anhydrides, and organic polycarboxylic acid lower alkyl esters. It is preferable to esterify an organic polycarboxylic acid and an organic polyhydric alcohol to obtain a polyester polyol, and then react the obtained polyester polyol with citric acid and an organic diamine, thereby achieving particularly high concentration. Moreover, it is possible to obtain a non-cresol solvent insulating coating with good properties. Next, each step of a preferred method for producing the polyesteramide resin insulation coating of the present invention will be described in detail. First, in the step of esterifying organic polycarboxylic acids and organic polyhydric alcohol, the blending ratio of the organic polycarboxylic acid component and the organic polyhydric alcohol component is adjusted so that the organic polyhydric alcohol component is in excess. Make it react. That is, both components are blended so that the ratio of total number of hydroxyl groups to total number of carboxy groups in the reaction mixture is 1.2 to 2.5, preferably 1.4 to 2.0.
If this ratio is too small, there is a risk of gelation before the reaction progresses sufficiently, and if it is too large, unreacted organic polyhydric alcohol will remain, which is not preferable. When carrying out this esterification reaction, a transesterification catalyst or a polycondensation catalyst is used. For example, organic acid salts such as acetates of lead, zinc, cadmium, cobalt, manganese, magnesium, etc., oxides of lead, antimony, etc., tetraalkyl titanates, etc. can be used. The amount used is 0.03 to 0.2 relative to the organic polycarboxylic acid component.
% by weight, preferably 0.05-0.15%. The esterification reaction is carried out in a conventional manner by raising the temperature of the reaction mixture to 160 to 200°C and reacting until the desired acid value is reached. The reaction is stopped when the acid value of the esterified product reaches 20 to 100, preferably 30 to 50. If the acid value of the produced polyester polyol is less than 20, the viscosity of the final polyester amide will be high, and if the acid value is 100 or more, the molecular weight will be too small and the performance of the paint film will be poor. Next, citric acid and an organic diamine are added to the polyester polyol obtained as described above and reacted to form a polyester amide. The blending ratio of citric acid is 5 to 50 mol%, preferably 10 to 40 mol%, based on the total number of moles of the organic polycarboxylic acid components used to obtain the polyester polyol. If the blending ratio of citric acid deviates from this range, the effect of using citric acid cannot be fully demonstrated, and if the blending ratio of citric acid is too small, the heat resistance of the paint film will not improve, while on the other hand, if the blending ratio of citric acid is too high, If it becomes too much, the paint film becomes hard, which is not preferable. The ratio of organic diamine used is 50% to citric acid.
~250 mol%, preferably 80-200 mol%.
If the proportion of organic diamine is too small, many unreacted carboxyl groups remain in the polyesteramide produced, resulting in a decrease in the performance of the paint film. Furthermore, if the proportion of organic diamine used is too large, the resulting polyesteramide will become too three-dimensional, resulting in poor solubility. The reaction of polyester polyol with citric acid and organic diamine is usually carried out when the temperature of the polyester polyol obtained in the above-mentioned esterification reaction is
After the temperature reaches 150℃ or below, add a predetermined amount of citric acid and organic diamine, and heat to 150-220℃, preferably 180-220℃.
The reaction is carried out at a temperature of 200° C. for several hours to several hours, and the reaction is stopped when the acid value reaches 15 to 100, preferably 20 to 40. For example, add citric acid and organic diamine to a polyester polyol that has reached a temperature of 150°C or less, raise the temperature to 150 to 190°C over 2 to 5 hours, and keep at this temperature for several hours until the specified acid value is reached. At that point, heating is stopped and some or all of the solvent is added to stop the reaction. If the acid value of the produced polyesteramide is less than 15, the molecule of the polyesteramide is too large and the viscosity of the paint becomes high. Furthermore, if the acid value exceeds 100, the insulation performance of the paint film deteriorates because the polyesteramide has not grown into molecules of sufficient size. Finally, if desired, a crosslinking agent is added at a temperature of 80°C or lower to obtain the desired high-concentration polyesteramide resin coating. The amount of the crosslinking agent added is usually 0.2 to 3.0% by weight based on the metal content relative to the resin content. If the amount of the crosslinking agent added is too small, the performance of the paint film will be insufficient, and if it is too large, the viscosity of the paint will increase markedly over time and the paint film will become hard, which are both undesirable. The present invention will be further explained in detail with reference to Examples and Comparative Examples below. Example 1 Trimellitic anhydride was added to a four-necked flask equipped with a stirrer, a thermometer, and a condenser with a measuring tube.
192g (1 mol), isophthalic acid 99.6g (0.6 mol), adipic acid 58.4g (0.4 mol), ethylene glycol 124g (2 mol), 1,4-butanediol 72.1g (0.8 mol), glycerin 110.5g (1.2 mol), xylol (reaction solvent) 30g and zinc acetate
0.18 g was charged, and the temperature was raised from room temperature to 150°C over 1 hour while stirring. Distillation started at 150℃. Raise the temperature from 150℃ to 180℃ in 3 hours to 185
When kept at ℃ for 2 hours, 99 g was distilled out to obtain a pale yellow transparent resin with an acid value of 55.1. Heating was stopped, and when the temperature of the resulting resin had fallen to 140°C, 76.8 g (0.4 mol) of anhydrous citric acid and 118.8 g (0.6 mol) of 4,4'-diaminodiphenylmethane were added, and heating was started again. The temperature was raised to 190°C over 2 hours, and the reaction was continued at this temperature for 1.5 hours. 11g of water distilled out, acid value
A reddish-brown resin of 23.6 was obtained. The heating was stopped, and 200 g of Hisolve DB (diethylene glycol monobutyl ether manufactured by Toho Chemical Industries, Ltd.), 225 g of ethylene glycol monomethyl ether, and 75 g of xylol were added to prepare a resin solution. Next, when the temperature drops to 80℃ or less, TBT100 [trade name of tetrabutyl titanate manufactured by Nippon Soda Co., Ltd.]. 22.5g of titanium (14%) dissolved in 22.5g of ethylene glycol monoethyl ether was gradually added over about 30 minutes. After the addition is complete, continue stirring for approximately 30 minutes. The obtained paint has a non-volatile content (200℃ x 2 hours)
The viscosity (at 30°C) was 59.6% and 28 poise. Table 1 shows an overview of the raw material formulation, synthesis conditions, and physical properties of the paint in Example 1. Example 2 Using an apparatus similar to that in Example 1, 153.6 g (0.8 mol) of trimellitic anhydride and 132.8 g (0.8 mol) of isophthalic acid were prepared.
g (0.8 mol), adipic acid 58.4 g (0.4 mol), ethylene glycol 155 g (2.5 mol), 1,4-butanediol 63.1 g (0.7 mol), glycerin 55.3
(0.6 mol), 30 g of xylol (reaction solvent), and 0.3 g of zinc acetate, and heated from room temperature while stirring.
The temperature was raised to 150°C in 1 hour. Distillation started at 150℃. Raise the temperature from 150℃ to 185℃ in 3 hours
When kept at 185° C. for 2 hours, 101 g was distilled out, yielding a pale yellow transparent resin with an acid value of 43. Heating was stopped, and when the temperature of the resulting resin had fallen to 140°C, 63 g (0.3 mol) of citric acid and 118.8 g (0.6 mol) of 4,4'-diaminodiphenylmethane were added, and heating was started again. The temperature was raised to .degree. C. over 2 hours, and the reaction was continued at this temperature for 2.5 hours. 12g of water distilled out, acid value
A reddish-brown resin of 22.8 was obtained. The heating was stopped, and 498 g of cresol and 91 g of xylene were added to prepare a resin solution. Next, when the temperature fell below 80°C, a solution of 20g of TBT100 dissolved in 20g of cresol was gradually added over about 30 minutes. After the addition was complete, stirring was continued for an additional 30 minutes. The resulting paint had a nonvolatile content (200°C x 2 hours) of 51.6% and a viscosity (30°C) of 29 poise. Similar to Example 1, Table 1 summarizes the raw material formulation, synthesis conditions, and paint physical properties of Example 2. Examples 3 to 10 Paints were prepared using the same equipment and procedure as in Examples 1 and 2, using the raw materials and synthesis conditions shown in the Examples 3 to 10 columns of Table 1. The physical properties of the obtained paint are also shown in Table 1. Comparative Example In the same apparatus as in Examples 1 to 10, 430.8 g of dimethyl terephthalate, 93 g of ethylene glycol, 76.8 g of glycerin and 0.4 g of zinc acetate were prepared.
A polyester resin obtained by reacting the following in a conventional manner was diluted with a mixed solvent of cresol/xylene=8/2, and 12 g of TBT100 was added to prepare a polyester resin paint. The non-volatile content of this paint is 35
%, and the viscosity was 28 poise. The polyester amide resin paints obtained in Examples 1 to 10 and the polyester resin paints obtained in Comparative Examples were coated on a copper wire with a conductor diameter of 1.0 mm using a 7 m long furnace. Upper temperature 470
℃, middle temperature 420℃, bottom temperature 370℃, linear speed 24m/
An insulated wire was manufactured by baking the wire seven times in minutes using the die method. The performance of each insulated wire obtained was as shown in Table 2.

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[Table] As is clear from the results in Table 2, each of Examples 1-
The performance of the insulated wire obtained in Example 10 was no inferior to that of a known polyester insulated wire. That is, according to the present invention, a non-cresol solvent can be used and an excellent insulated wire with a high concentration can be obtained, which has great industrial value.

Claims (1)

[Scope of Claims] 1. Organic polycarboxylic acids selected from the group consisting of organic polycarboxylic acids, organic polycarboxylic acid anhydrides, and organic polycarboxylic acid lower alkyl esters, organic polyhydric alcohols, and citric acid. An electrical insulation paint consisting of a polyesteramide resin obtained by reacting with an organic diamine and an organic solvent. 2 The organic solvent is a non-cresol solvent, and has the general formula R ₁ O (CHR ₂ - CH ₂ O) _o H (where R ₁ is a lower alkyl group, R ₂ is a hydrogen or methyl group, and n is 1 to 3). 50 glycol ether solvents (integers)
The electrical insulation paint according to claim 1, which is a non-cresol solvent containing ~100%. 3. The electricity according to claim 2, wherein the organic solvent used in combination with the glycol ether solvent is a non-cresol solvent selected from the group consisting of alcohol solvents, isophorone, and aromatic hydrocarbon solvents. Insulating paint. 4. The electrically insulating paint according to claim 1, which is obtained by adding a crosslinking agent to a resin solution consisting of a polyesteramide resin and an organic solvent. 5. The electrically insulating paint according to claim 1, wherein the polyesteramide resin has an acid value of 15 to 100. 6. The electrically insulating paint according to claim 5, which has an acid value of 20 to 40. 7 An organic polycarboxylic acid selected from the group consisting of an organic polycarboxylic acid, an organic polycarboxylic acid anhydride, and an organic polycarboxylic acid lower alkyl ester is subjected to an esterification reaction with an organic polyhydric alcohol to obtain a polyester polyol. A method for producing a polyester amide resin electrical insulating paint, which comprises reacting the obtained polyester polyol with citric acid and an organic diamine to obtain a polyester amide resin, and dissolving the resin in an organic solvent to obtain an electrical insulating paint. . 8. The method for producing an electrically insulating paint according to claim 7, wherein the polyester polyol has an acid value of 20 to 100. 9. The method for producing an electrically insulating paint according to claim 7, wherein 5 to 50 mol% of citric acid is used based on the acid component of the polyester polyol. 10 The acid value of polyesteramide resin is 15 to 100
A method for producing an electrically insulating paint according to claim 7. 11 Claim 1 having an acid value of 20 to 40
A method for producing an electrically insulating paint according to item 0. 12 The organic solvent is a non-cresol solvent, and has the general formula R ₁ O (CHR ₂ - CH ₂ O) _o H (wherein R ₁ is a lower alkyl group, R ₂ is a hydrogen or methyl group, and n is 1 to 3
(an integer of )
The method for producing an electrically insulating paint according to claim 7, wherein the electrically insulating paint contains 50 to 100% of a non-cresol solvent. 13 Claim 1, wherein the organic solvent used in combination with the glycol ether solvent is a non-cresol solvent selected from the group consisting of alcohol solvents, isophorone, and aromatic hydrocarbon solvents.
2. A method for producing an electrically insulating paint according to item 2.