JPS6231747B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an insulating paint using an excellent low-pollution and low-toxicity solvent. Currently, as electrical insulating paints, the electrical,
Polyester resin paints are widely used because of their mechanical and chemical performance and cost. Furthermore, as electrical equipment has become smaller, lighter, and more sophisticated, the required properties of insulating paints have also increased.
Demand for polyesterimide resin paints and polyesteramideimide resin paints with high heat resistance is also increasing. The main solvents for these resin paints are cresol,
Phenols such as phenol and xylenol are used, but these phenols have a strong irritating odor, and if they come into contact with the skin, there is a risk of irritation, so care must be taken when handling them. In order to deal with such problems, a resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol has the following general formula R ₁ -(O-C _n H _2n )- _o OH or R ₁ -(O-C _n H _2n )- _o OCOR ₂ [R ₁ and R ₂ are lower alkyl groups, aryl groups or aralkyl groups, m is an integer of 2 to 3, n is 1 to 3
An insulating paint made by dissolving a specific polyhydric alcohol derivative represented by the following integer in a solvent has been proposed. (Special Publication No. 53-34206, Japanese Patent Publication No. 50-150737,
(Japanese Patent Application Laid-open No. 16342/1983) These previously proposed insulating paints do not use phenols as solvents, so they are easy to handle because they do not have an irritating odor and do not cause irritation when they come into contact with the skin. be. However, in these proposed paints, when dissolving the resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol into the polyhydric alcohol derivative, it is necessary to perform the dissolution at a temperature of 180°C or lower. be. When melting is carried out at a temperature exceeding 180°C, the properties of insulated wires manufactured using the resulting paint, such as heat resistance, heat softening resistance, and abrasion resistance, are significantly reduced. The cause of this is that the polyhydric alcohol derivative reacts with the resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol, causing alcoholysis and/or transesterification reaction, resulting in the formation of a resin. This is to cut the ester bonds present in the molecular chain and lower the molecular weight of the resin. In order to prevent such a decrease in the molecular weight of the resin during dissolution and, ultimately, a decrease in the characteristics of insulated wires manufactured using the resulting paint, it is necessary to dissolve the resin at a temperature of 180°C or lower. It needs to be dissolved in polyhydric alcohol derivatives. However, the resins used in paints for insulated wires that use phenols as solvents, which are currently commonly used, usually have a very high viscosity at temperatures below 180°C, and it is difficult to dissolve the resin in the solvent as it is. . Therefore, in the paints proposed so far, the degree of polymerization is reduced in the reaction process of polyhydric carboxylic acid or its derivative and polyhydric alcohol.
Produce low molecular weight and low viscosity resin, and
It is dissolved in the polyhydric alcohol derivative at a temperature of 180°C or lower, or if the degree of polymerization is made to be the same, the synthesized resin is once taken out, cooled, and the solidified resin is crushed and mixed with a solvent, A commonly used method was to reheat and dissolve the material. In the former method, the insulated wire manufactured by coating and baking the paint obtained has a low molecular weight, and its properties such as heat resistance, heat softening resistance, and abrasion resistance are significantly inferior; The addition of cooling, crushing, and reheating operations to the paint manufacturing process increases the cost and time required for manufacturing the paint. These problems were a major obstacle in producing the proposed paint. Therefore, we use safer, less polluting, and less toxic solvents to improve the thermal stability, heat deterioration resistance, flexibility, electrical insulation, hydrolysis resistance, chemical resistance, etc. of conventional insulated wires. An insulating paint that maintains the thermal, mechanical, electrical, and chemical properties of electric wires without impairing them, and that can be manufactured using the same manufacturing process as that using cresol solvents, and a manufacturing method thereof. Development has been long awaited. The present invention was completed as a result of repeated studies to meet these demands. The present invention provides a resin that is obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol and whose Gardner-Holdt viscosity of an m-cresol solution with a resin concentration of 40% by weight at 25°C is W or more.
For 100 parts by weight, use 3 to 70 parts by weight of a solvent that dissolves the resin when heated and does not decompose, and heat at 200°C.
It is characterized by dissolving it by heating at a temperature above, and then dissolving it in a solvent whose main component is a specific glycol ether at a temperature of 180°C or below. Examples of polycarboxylic acids or derivatives thereof used in the present invention include isophthalic acid, terephthalic acid, orthophthalic acid, phenylindane dicarboxylic acid, benzophenonedicarboxylic acid, adipic acid, succinic acid, maleic acid, and sebacic acid. , isosebacic acid, dimer acid, tetrachlorophthalic acid,
Trimellitic acid, hemimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, general formula [R is a divalent aliphatic, alicyclic, or aromatic hydrocarbon group having at least 2 carbon atoms, or a combination of these groups, and further includes those having a side chain in the chain For example, R is -
(CH ₂ ) ₆ ―,

【formula】

【formula】

Examples include compounds having an imide ring in the molecule represented by the following formula, and derivatives such as anhydrides and esters of these acids. From the viewpoint of heat resistance of the coating film, terephthalic acid, isophthalic acid, and compounds having an imide ring in the molecule are more preferable. or its lower alkyl esters. Examples of polyhydric alcohols used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-butanediol, 1,4-
Butanediol, 1,3-propanediol,
1,6-hexanediol, hydrogenated bisphenol A (hydrogenated 4,4'-dihydroxydiphenylpropane), 1,4-cyclohexanediethanol, 1,4-cyclohexanedimethanol, 1.
4-pentanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, diglycerin, dipentaerythritol, tris(2
-hydroxypropyl) isocyanurate, tris(2-hydroxyethyl) isocyanurate, etc. From the viewpoint of the flexibility and heat resistance of the coating film, ethylene glycol, glycerin, trimethylolpropane, and tris(2-hydroxyethyl) isocyanurate are more preferred. In the present invention, the molecular weight of a resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol was measured using a Gardner-Holdt foam viscometer. It is common practice to express the molecular weight of a resin by its solution viscosity by utilizing the correlation between the molecular weight of a polymeric substance such as a polyester resin and its solution viscosity. That is, it is known that a polymeric substance with a high solution viscosity has a higher average molecular weight than a polymeric substance with a lower solution viscosity. The Gardner Holt foam viscometer measures the viscosity of liquids.
This is a viscometer that measures the rate of rise of bubbles, and compares the rate of rise of bubbles between a standard solution of known viscosity and a sample solution, and compares the viscosity of the standard solution and sample solution. Gardner-Holdt viscosity is expressed in terms of alpha. Its viscosity value (25℃, Stokes)
Some of the relationships are shown below.

[Table] When carrying out the present invention, first, a polyhydric carboxylic acid or its derivative and a polyhydric alcohol are placed in a reaction container, and the temperature of the reaction system is raised from room temperature to 240°C over 5 to 10 hours. and continue the reaction at this temperature. At this time, the resin is sampled from time to time, an m-cresol solution with a resin concentration of 40% by weight is prepared, and the Gardner-Holdt viscosity of this solution is measured. The point at which the Gardner-Holdt viscosity at 25° C. exceeds W, that is, the point at which the solution viscosity becomes higher than W, must be defined as the end point of the reaction. If the reaction is terminated at a viscosity lower than W, the heat resistance of the coating film will be insufficient, which is not preferable. Further, from the viewpoint of the flexibility, abrasion resistance and heat resistance of the coating film, it is more preferable to set the reaction end point at the point at which Z ₃ or higher, that is, the point at which the solution viscosity becomes higher than Z ₃ . During this reaction, lead acetate, zinc acetate, lead naphthenate, tetrabutyl titanate, sodium carbonate,
It is desirable to use a transesterification catalyst such as potassium carbonate. Further, sublimation of the starting materials can be prevented by adding a solvent such as xylene or solvent naphtha to these starting materials in advance or during the reaction. By heating during the reaction, these solvents are distilled out of the reaction system together with by-products lower alcohol and water. Next, in the reaction vessel, a solvent that dissolves the generated resin when heated and does not cause decomposition of the resin is added to dissolve the resin, lower the temperature of the reaction system, stop the reaction, and reduce the melt viscosity of the solution. urge At this time, the amount of solvent added to the reaction vessel is
For every 100 parts by weight, 3 to 70 parts by weight are required. If the amount is less than 3 parts by weight, the melt viscosity of the solution after adding the solvent will be high, and the subsequent dissolution into a solvent containing glycol ether as a main component will not proceed smoothly. In addition, if the amount is 70 parts by weight or more, the object of the present invention, which is higher safety, lower pollution,
Impairs the effectiveness of paints using low-toxicity solvents. The temperature of the resin solution thus obtained is 180°C.
℃ or less, more preferably 150℃ or less, the following general formula R-(O-C _n H _2n )- _o OH [R is a lower alkyl group, aryl group, aralkyl group, m is 2-3 an integer, n is an integer of 1 to 3] A solvent containing glycol ether as a main component is added to the reaction vessel to dissolve the resin solution.
The concentration of resin content can be changed arbitrarily, but 20
From the viewpoint of workability, it is appropriate to set the content to about 60% by weight. Melting the resin used in the present invention under heat,
As a solvent that does not cause decomposition of the resin, N.
N-dimethylformamide, N・N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide or phenol, O-
Cresol, m-cresol, P-cresol,
Cresylic acid, 2,3-xylenol, 2,4-
Xylenol, 2,5-xylenol, 2,6-
xylenol, 3,4-xylenol, 3,5-
Examples include xylenol and mixtures thereof. In addition, glycol ethers represented by the general formula R-(O- _CnH2n ) _-oOH include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether _, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and ethylene glycol monophenyl. Ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether,
Diethylene glycol monophenyl ether, triethylene glycol monoethyl ether, triethylene glycol monoethyl ether, triethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, Examples include propylene glycol monophenyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monophenyl ether, and the like. From the viewpoint of solubility in polyester resin, R is more preferably a phenyl group.

Glycol monophenyl ether represented by the formula, such as ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, triethylene glycol monophenyl ether, propylene glycol monophenyl ether, dipropylene glycol monophenyl ether, tripropylene glycol monophenyl ether , or R is a lower alkyl group, and n=2, m
=2. Diethylene glycol monoalkyl ethers represented by the general formula R-(OC ₂ H ₄ )- ₂ OH, such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, and diethylene glycol monobutyl ether, are desirable. These glycol ethers can be used alone, or two or more types of glycol ethers can be used in combination. The paint thus obtained can be used as is for insulated wires, but it is preferable to add a curing agent to improve the physical and chemical properties during baking. Examples of curing agents include tetrabutyl titanate, tetraisopropyl titanate, and tetraphenyl titanate, which are commonly used in electrical insulation paints.
Organic titanium compounds such as dibutyl ditriethanolamine titanate, dibutyl diacetoacetic acid ethyl titanate, dibutyl diacetylacetone titanate, etc. can be used. In addition, blocking isocyanate compounds may be used in combination, and in addition, zinc naphthenate, cobalt naphthenate, zinc octenoate, manganese octenoate,
It is also effective to add metal salts of organic acids such as tin octenoate. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these are merely examples, and the present invention is not limited to these Examples. In the following Examples and Comparative Examples, the reaction was carried out in a reaction vessel equipped with one or two four-necked flasks, a condenser, a thermometer, a nitrogen inlet tube, and a stirring device, with sufficient stirring. Further, the viscosity was measured at 25° C. using a Gardner-Holdt viscometer after preparing an m-cresol solution with a resin concentration of 40% by weight. In addition, when applying and baking paint onto copper wires, please be sure to
Baking was carried out on copper wire with a diameter of 1.0 mmφ using a 10 m vertical furnace with furnace temperatures of 360°C in the upper part, 320°C in the middle, and 260°C in the lower part. Comparative Example 1 Dimethyl terephthalate 311g (1.6mol), ethylene glycol 74g (1.2mol), glycerin 60g (0.65mol), tris(2-hydroxyethyl)
39 g (0.15 mol) of lead isocyanurate acetate, 0.64 g, were reacted in 300 g of xylene. While gradually increasing the temperature from 140°C to 240°C, xylene and methanol, a by-product of the reaction, were distilled out of the system through a condenser. When the temperature reached 240℃, sample the contents of the flask while keeping it warm at this temperature, measure the Gardner-Holdt viscosity, stop heating when it reached V, and immediately add cresol to make the resin concentration 40%. , the resin was heated and dissolved. Thereafter, 7 g of tetrabutyl titanate and 7 g of zinc octenoate were added. The viscosity of this paint at 30° C. was 8 poise using a B-type rotational viscometer. Table 1 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Comparative example 2 Gardner-Holdt viscosity is W to X (between W and X)
A coating material was obtained in the same manner as in Comparative Example 1, except that heating was stopped when the temperature reached the point where the coating material had become dry. The viscosity of this paint at 30° C. was 13 poise using a B-type rotational viscometer. Table 1 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Comparative Example 3 A coating material was obtained in the same manner as in Comparative Example 1, except that heating was stopped when the Gardner-Holdt viscosity reached _Z3 . The viscosity of this paint at 30° C. was 52 poise using a B-type rotational viscometer. Table 1 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire.

【table】

[Table] As can be seen from Table 1, when manufacturing a paint using a resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol, the reaction was completed before the Gardner-Holdt viscosity was lower than W. In this case, the characteristics of the insulated wire manufactured using the resulting paint do not meet the standards for polyester copper wire specified in JIS C 3210, for example. Therefore, the polymerization degree of the resin needs to be at least W or higher in Gardner-Holdt viscosity. Further, from the viewpoint of heat resistance, abrasion resistance, deterioration resistance, etc. of the coating film, it is more preferable to set the point at which Z ₃ or higher is reached as the reaction end point. Comparative Example 4 The same raw materials as in Comparative Example 1 were used and the same reaction was carried out. Heating was stopped when the Gardner-Holdt viscosity reached Z ₃ , and immediately thereafter, ethylene glycol monophenyl ether was added so that the resin concentration was 40%, and the resin was dissolved by heating. Thereafter, 7 g of tetrabutyl titanate and 7 g of zinc octenoate were added. The viscosity of this paint at 30° C. was 8 poise using a B-type rotational viscometer. Table 2 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Comparative Example 5 The same reaction as in Comparative Example 1 was carried out using the same raw materials. Heating was stopped when the Gardner-Holdt viscosity reached Z ₃ , and the mixture was cooled. When the temperature of the resin reaches 220℃,
The viscosity gradually increased and reached a very high viscosity at 200°C, making it impossible to stir and dissolve in a solvent. Comparative Example 6 The same raw materials as in Comparative Example 1 were used and the same reaction was carried out. When the Gardner-Holdt viscosity reached _Z3 , heating was stopped, the resin was taken out, and the resin was cooled to room temperature. This resin was pulverized, ethylene glycol monophenyl ether was added to the resin to give a resin concentration of 40%, and the mixture was heated and dissolved at a temperature of 190°C. Thereafter, 7 g of tetrabutyl titanate and 7 g of zinc octenoate were added. The viscosity of this paint at 30°C was 10 poise as measured by a B-type rotational viscometer. Table 2 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Comparative Example 7 A resin similar to that synthesized in Comparative Example 6 was synthesized, cooled and pulverized, and then ethylene glycol monophenyl ether was added to give a resin concentration of 40%, and the mixture was heated and dissolved at a temperature of 170°C. . Thereafter, 7 g of tetrabutyl titanate and 7 g of zinc octenoate were added. The viscosity of this paint at 30° C. was 40 poise using a B-type rotational viscometer. Table 2 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire.

[Table] As you can see from Table 2, using the same raw materials,
Even if a resin is synthesized through a similar reaction and with a constant degree of polymerization, when producing a paint using the resin, the temperature at which the resin is dissolved in the glycol ether solvent proposed by the present invention is 180°C. If it exceeds this, properties such as heat softening resistance, abrasion resistance, thermal shock resistance, and heat deterioration resistance will deteriorate. On the other hand, at temperatures below 180°C, the properties are almost the same as in the case where cresol is used as the solvent (Comparative Example 2). However, in the production method of Comparative Example 7, cooling and pulverization operations are added after resin synthesis, which is undesirable from the viewpoint of paint production cost and time. Example 1 The same raw materials as in Comparative Example 1 were used and the same reaction was carried out. Heating was stopped when the Gardner-Holdt viscosity reached Z ₃ , and immediately thereafter 25 g of cresol was added and dissolved, followed by cooling. This solution remained a viscous liquid even at a temperature of 170°C. At this temperature, ethylene glycol monophenyl ether was added and dissolved so that the resin concentration was 40%. Furthermore, 7 g of tetrabutyl titanate and 7 g of zinc octenoate were added. The viscosity of this paint at 30°C was 41 poise as measured by a B-type rotational viscometer. Table 3 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Example 2 Dimethyl terephthalate 272g (1.4 mol), trimellitic anhydride 77g (0.4 mol), 4,4'-diaminodiphenylmethane
44 g (0.2 mol), ethylene glycol 74 g (1.2 mol), glycerin 74 g (0.8 mol), and lead acetate 0.56 g were reacted in 250 g of xylene in the same manner as in Comparative Example 1 until the Gardner-Holdt viscosity was between Z ₄ and _{Z 5} . At this point, heating was stopped, 40 g of N-methyl-2-pyrrolidone was added and dissolved, and the mixture was cooled. When the temperature reached 150°C, propylene glycol monophenyl ether was added and dissolved so that the resin concentration was 44.5%. Furthermore, 8 g of tetrabutyl titanate and 8 g of zinc octenoate were added. The viscosity of this paint at 30° C. was 57 poise using a B-type rotational viscometer. Table 3 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Example 3 Dimethyl terephthalate 155g (0.8 mol), trimellitic anhydride 307 (1.6 mol), 4,4'-diaminodiphenylmethane
159g (0.8 mol), ethylene glycol 74g (1.2 mol), tris(2-hydroxyethyl)isocyanurate 209g (0.8 mol), and lead acetate 0.32g were reacted in 150g of xylene in the same manner as in Comparative Example 1. When the viscosity reached _Z7 , heating was stopped, 50 g of 2,4-xylenol was added and dissolved, and the mixture was cooled. When the temperature reached 170°C, diethylene glycol monomethyl ether was added and dissolved so that the resin concentration was 35%. Furthermore, 15 g of tetrabutyl titanate and 15 g of zinc octenoate were added. The viscosity of this paint at 30° C. was 50 poise using a B-type rotational viscometer. Table 3 shows the properties of the insulated wire obtained by coating and baking this paint onto the copper wire. Furthermore, as Comparative Example 8, the characteristics of an insulated wire obtained from a polyester paint using a currently commonly used phenol as a solvent are also shown in the same table.

[Table] As is clear from the examples, the method for manufacturing insulated wires proposed in the present invention has a major obstacle in manufacturing paints using polyhydric alcohol derivatives as solvents, which have been proposed in the past. The operation of dissolving the resin in a solvent becomes very easy, and Table 3
As can be seen from the above, the properties of the insulated wire obtained are equivalent to or better than those of the insulating paint obtained from the currently used paint using a phenolic carrier.

Claims (1)

[Claims] 1. A resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol, in which the Gardner-Holdt viscosity of an m-cresol solution with a resin concentration of 40% by weight at 25°C is W or more. , For 100 parts by weight of the resin, use 3 to 70 parts by weight of a solvent that dissolves the resin when heated and does not decompose, and after heating and melting at a temperature of 200°C or higher, further at a temperature of 180°C or lower, perform the following process. _A glycol ether represented by the general formula R-(O- _CnH2n ) _-oOH [R is a lower alkyl group, aryl group, or aralkyl group, m is an integer of 2 to 3, and n is an integer of 1 to 3] A method for producing an insulating paint characterized by dissolving it in a solvent as a main component. 2 The resin obtained by reacting polyhydric carboxylic acid or its derivative with polyhydric alcohol is
The Gardner-Holdt viscosity of an m-cresol solution with a resin concentration of 40% by weight is _Z3 or higher. A method for producing an insulating paint according to claim 1. 3 Glycol ether represented by the general formula R-(O-C _n H _2n )- _o OH is represented by the following general formula [Formula] [m is an integer of 2 to 3, n is an integer of 1 to 3] The method for producing an insulating paint according to claim 1, wherein the insulating paint is glycol monophenyl ether. 4. The method for producing an insulating paint according to claim 3, wherein the glycol monophenyl ether represented by the general formula [Formula] is ethylene glycol monophenyl ether or propylene glycol monophenyl ether. 5. Claim 1 _, wherein the glycol ether represented by the general formula R-(O- _CnH2n ) _-oOH is diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, or diethylene glycol monobutyl ether. A method for producing insulating paint. 6 Polycarboxylic acids or derivatives thereof include terephthalic acid, isophthalic acid, compounds having an imide ring in the molecule shown below, [R is a divalent fatty acid having at least 2 carbon atoms, an alicyclic group, an aromatic hydrocarbon group, or a combination of these groups, and an organic group including one having a side chain in the chain. It is. ] Or the method for producing an insulating paint according to claim 1, which is a lower alkyl ester thereof. 7. The method for producing an insulating paint according to claim 1, wherein the polyhydric alcohol is ethylene glycol, glycerin, trimethylolpropane, or tris(2-hydroxyethyl) isocyanurate. 8 The solvent that heats and dissolves the resin obtained by reacting a polyhydric carboxylic acid or its derivative with a polyhydric alcohol at a temperature of 200°C or higher is N/N-dimethylformamide, N/N-dimethylacetamide, N- The method for producing an insulating paint according to claim 1, wherein the insulating paint is methyl-2-pyrrolidone, dimethyl sulfoxide, or a mixture of two or more thereof. 9 The solvent that heats and dissolves the resin obtained by reacting polyhydric carboxylic acid or its derivative with polyhydric alcohol at a temperature of 200°C or higher is phenol, O
-Cresol, m-cresol, P-cresol, cresylic acid, 2,3-xylenol, 2.
4-xylenol, 2.5-xylenol, 2.
6-xylenol, 3,4-xylenol, 3.5
- The method for producing an insulating paint according to claim 1, which is xylenol or a mixture of two or more thereof.