JPH0154383B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a novel insulating paint containing polyester as a main component. Polyester wire enamel using phenols as a solvent is well known and has long been used as a general-purpose wire enamel due to its good balance of electrical, thermal, and mechanical performance. moreover,
As a method of imparting higher heat resistance to polyester, tris(2-hydroxyethyl) isocyanurate (hereinafter referred to as
It's called THEIC. ) was proposed (Special Publication No. 39-28288), and with subsequent improvements,
In practical terms, the grade of polyester wire enamel has improved to the point where it is used in some of the F to H classes. On the other hand, in recent years, as pollution issues have become more prominent, there has been a strong demand for lower pollution levels in the solvents used in wire enamels from the viewpoint of preventing air pollution and managing the health of workers. Due to these circumstances, the general formula RO(-C _o H _2o O)- _x H (in the formula, R is an alkyl group having 1 to 6 carbon atoms, and n is 2 or 3, and x is 1 to 3
is an integer. The use of monoalkyl ethers of alkylene glycol (hereinafter referred to as glycol alkyl ethers) represented by (hereinafter referred to as glycol alkyl ethers) as a solvent for wire enamels has been proposed in Japanese Patent Publication No. 18891/1983 as a solvent for polyurethane polymers. Polyesters used for wire enamels have conventionally been produced by polycondensing glycols and trivalent or higher hydroxy components with dicarboxylic acids. However, methods for dissolving such polyesters in glycol alkyl ether solvents include a method of producing them by a specific blend under specific conditions (Japanese Patent Application Laid-Open No. 150737/1982), and a method of limiting the degree of reaction of the polymer (Japanese Patent Application Laid-open No. 150737/1983). 16342) has been proposed. However, the polyester wire enamel obtained by these methods has a heat resistance of only B class at most, so even if it can meet the low pollution requirements, it is difficult to miniaturize motors, transformers, etc. and improve reliability. The increasing demand for heat resistance of insulating materials has not yet been met. According to the research conducted by the present inventors, the following knowledge was obtained regarding polyester electrical insulation paints that are stably soluble in monoalkyl or monophenyl ethers of alkylene glycols (hereinafter referred to as glycol ethers) and have excellent heat resistance. . In other words, when using glycol ether as a solvent for polyester insulation paint, polyester has a tolerance range for glycol ether solvents, and even if it is transparent at high solid content or high viscosity, it will become cloudy and separate when diluted to near the practical viscosity. Even if it is transparent at high concentrations, it becomes cloudy when cooled to around 50°C. Furthermore, when only polyester is dissolved in glycol ether, even though it is transparent, it becomes cloudy when mixed with a curing agent such as titanate ester. It became clear that the dissolution stability was very poor. Furthermore, it was found that the higher the content of THEIC, a heat-resistant component, in the hydroxyl component of such polyester, the smaller the solvent tolerance range due to glycol ether in the polyester obtained, making it impossible to obtain a stably soluble insulating coating. did. Accordingly, an object of the present invention is to provide an electrically insulating paint that has excellent heat resistance, electrical properties, and safety. These objectives are such that the ratio of hydroxyl group equivalent to carboxyl group equivalent is within the range of 1.3:1 to 2:1, and that the hydroxyl group by tris (2-hydroxyethyl) isocyanurate is 30 equivalent% or more and the general Formula RO(-C _o H _2o O) - _x H (wherein, R is an alkyl group or phenyl group having 1 to 6 carbon atoms, n is 2 or 3, and x is an integer of 1 to 3 The above-mentioned polyester is a polycondensate of a dicarboxylic acid and a hydroxyl component containing 5 to 30 equivalent % of a hydroxyl group derived from a monoalkyl or monophenyl ether (hereinafter referred to as glycol ether) of an alkylene glycol represented by This is achieved using an electrically insulating paint made from an alkylene glycol alkyl or monophenyl ether solution. In the present invention, the hydroxy component of the polyester and the glycol ether represented by the above general formula used as a solvent when the polyester is used as a solution for insulating paint, etc. include diethylene glycol monomethyl ether, monoethyl ether, mono-n- Propyl ether, monoisopropyl ether, mono-n-butyl ether, monoisobutyl ether, monohexyl ether, monophenyl ether; monomethyl ether of dipropylene glycol, monoethyl ether, mono-n-propyl ether, monoisopropyl ether, mono-n -butyl ether, monobutyl ether, monohexyl ether, monophenyl ether; monomethyl ether, monoethyl ether, monoisopropyl ether, mono-n-butyl ether, monophenyl ether of triethylene glycol; monomethyl ether, monoethyl ether of tripropylene glycol , monoisopropyl ether, mono-n-butyl ether, monophenyl ether; monophenyl ether of ethylene glycol, and the like. Among these compounds, compounds in which R in the above general formula is an alkyl group having 1 to 4 carbon atoms and x is 2 or 3, and R is a phenyl group and x is an integer of 1 to 3 are preferred, and in particular diethylene glycol. Monomethyl ether, monoethyl ether of diethylene glycol, monoisopropyl ether of diethylene glycol, mono-n- of diethylene glycol
Preferred are butyl ether, monomethyl ether of dipropylene glycol, monoethyl ether of dipropylene glycol, monophenyl ether of diethylene glycol, monophenyl ether of dipropylene glycol, and the like. Examples of hydroxy components other than the glycol ether and THEIC include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, neo Pentyl glycol, 1,6-hexanediol,
1,4-cyclohexanedimethanol, 2,2,
There are 4-trimethyl-1,3-pentanediol, trimethylene glycol, N,N-bishydroxyethyl-5,5-dimethylhydantoin, hydrogenated bisphenol A, etc., and polyols include glycerin, trimethylolethane, and trimethylol. Propane, 1,3,5-trihydroxyethyl-2,4,6-hexahydrotriazine, etc. are used. Examples of dicarboxylic acids include terephthalic acid and its lower alkyl esters, such as dimethyl terephthalate, diethyl terephthalate, and dibutyl terephthalate; isophthalic acid and its lower alkyl esters, such as dimethyl isophthalate, diethyl isophthalate, and dibutyl isophthalate; benzophenone-4; 4-dicarboxylic acid and its lower alkyl esters, such as benzophenone-4,4-dicarboxylic acid dimethyl ester, adipic acid, azelaic acid, etc. can be used. The polyester used in the present invention is completely novel in that a monohydric alcohol such as glycol ether coexists as a part of the hydroxyl component during polyester synthesis to modify the molecular terminal. To achieve effectiveness, the amount of glycol ether used ranges from 5 to 30 equivalent % of the hydroxy component, preferably from 10 to 25 equivalent %. In other words, if the amount of glycol ether used during the reaction is less than 5 equivalent %, when glycol ether is used as a solvent, the polymer will have a small solvent tolerance, and even if it becomes a temporarily transparent solution, it will not be able to be used as a diluent or curing agent. A stable insulating coating cannot be obtained because it becomes cloudy or separates during mixing or for a short period of time during storage. On the other hand, using more than 30 equivalent % is preferable from the viewpoint of solubility of the polyester, but various properties as an insulating coating material will deteriorate. The amount of THEIC used as a heat-resistant component needs to be 30 equivalent % or more in the hydroxy component, but preferably 40 to 80 equivalent %. That is,
If the amount used is less than 30 equivalent %, the heat resistance effect obtained by using THEIC will be insufficient. Therefore, the composition of the hydroxy component is
It is also effective to set the total amount of THEIC and glycol ether to 100% by equivalent. However, the most preferred composition of the hydroxy component is THEIC, glycol ether and ethylene glycol, and the equivalent ratio thereof is most preferably 50 to 70:10 to 25:40 to 5. Terephthalic acid is preferred as the dicarboxylic acid. In the present invention, in order to more smoothly synthesize the polyester and more effectively achieve the purpose of the invention, the ratio of the hydroxyl component to the dicarboxylic acid at the initial stage of the polyester synthesis reaction is 1.3:1 to 1.3:1 in terms of equivalent ratio. Preferably, the ratio is 2:1;
The most preferred range is 1.5:1 to 1.8:1.
When a large amount of THEIC is contained as a hydroxy component, if the equivalent ratio of the hydroxy component is less than 1.3, the resulting polyester will have a high viscosity, making the synthesis reaction difficult, and the modification effect with glycol ether will also be small. On the other hand, if the equivalent ratio exceeds 2, the molecular weight of the polyester is so small that an insulating paint with good properties cannot be obtained and its stability is also poor. Synthesis of the polyester used in the present invention is usually carried out as follows. That is, after blending a hydroxy component and a dicarboxylic acid having the above composition so that the ratio of hydroxy group equivalent to carboxyl group equivalent is within the range of 1.3:1 to 2:1, nitrogen and carbonic acid are added. The polycondensation reaction is carried out by heating to a temperature of 120 to 300°C, preferably 150 to 260°C, under an atmosphere of an inert gas such as gas, while distilling off the water produced. The polyester thus obtained has a wide solvent tolerance range for glycol ether and is stably soluble in this solvent.The insulating paint of the present invention obtained by mixing a curing agent has excellent heat resistance and electrical properties. It is excellent. The obtained solution of the new polyester is mixed with a known curing agent to form the electrical insulation coating of the present invention (hereinafter referred to as
It is called insulating paint. ). Examples of such curing agents include titanates, phenolic resins, aminoplast resins, organic acid metal salts,
Blocked polyisocyanates and the like can be used. Titanates include tetraisopropyl titanate, tetrabutyl titanate, tetraphenyl titanate, tetrahexyl titanate, dibutyltriethanolamine titanate, and the like. Titanates are extremely excellent curing agents for insulating paints and are always used in polyester-based insulating paints, but when glycol ether is used as a solvent, conventional polyesters are transparent even if they are a polymer alone. , they tend to become cloudy or separate when mixed with titanates, and lack stability. However, the polyester used in the present invention is stable even when titanate is mixed in its glycol ether solution. The amount of titanate mixed in the present invention is preferably 1 to 10 parts by weight per 100 parts by weight of polyester. If it is less than 1 part by weight, curing will be insufficient, while if it is used in excess of 10 parts by weight, stability will be impaired and it will be difficult to obtain a good enameled wire when coated with enamel. Examples of the phenolic resin include those obtained by condensing phenol, cresol, xylenol, other alkylphenols, or mixtures thereof with formaldehyde. Examples of the aminoplast resin include melamine-formaldehyde resin and benzoguanamine-formaldehyde resin.
Examples of metal salts of organic acids include cobalt naphthenate,
These include zinc naphthenate, cobalt octenoate, zinc octenoate, and cadmium linolenate. Blocked polyisocyanates include those that have two or more isocyanate groups in one molecule and are stabilized with phenol, cresol, etc., such as Desmodelur T and CT Stable manufactured by Bayer. It is effective in accelerating curing. When using the obtained polyester to prepare the insulating coating of the present invention, if a co-solvent is used, an aromatic carbonized solvent such as benzene, toluene, xylene, aromatic naphtha (for example, Solbetsuso #100, Solbetsuso #150, etc.) may be used. Although hydrogen and aliphatic naphthas (such as mineral spirits) can be used, aromatic naphthas are preferred. Although the use of such co-solvents does not improve solubility, it is effective in reducing the overall cost of the solvent. The insulating paint of the present invention obtained in this way is
Using known coating methods and wire speeds, copper,
It can be applied to wires of silver, aluminum or other metals, and the coating cures at known temperatures.
For example, it is carried out at a temperature of 250 to 500°C. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the following, all parts and % mean parts by weight and % by weight unless otherwise specified. Additionally, the following abbreviations are used below: E G=ethylene glycol THEIC=tris(2-hydroxyethyl)isocyanurate TPA=terephthalic acid TPT=tetraisopropyl titanate TBT=tetrabutyl titanate G L=glycerin Example 1 In this example, OH:COOH=1.4:1. ,and
This is an example of a polyester and an insulating paint synthesized using diethylene glycol monoethyl ether for about 16 equivalents of the hydroxy component, which has a content of THEIC of 50 equivalents. Grams of reaction components (1) EG 133.3 (2) Diethylene glycol monoethyl ether 268.0 (3) THEIC 549.0 (4) TPA 747.9 In two flasks equipped with a stirrer, thermometer, distillation condenser and nitrogen gas inlet, Reaction component (1) ~
(4) was added, and the mixture was heated and heated while stirring. The first distillate was obtained when the temperature reached 204°C.
The reaction temperature was gradually raised to 235°C and the reaction was continued. From the reaction system when the distillate reached 160 c.c.
The TPA crystals disappeared and it became transparent. At this point, a large amount of nitrogen gas was flowed into the flask for an additional 70 min.
After removing cc of distillate, the reaction product was removed from the flask. The viscosity of a 50% diethylene glycol monoethyl ether solution of the final polymer is 25℃
It was T1/4 (Gardner viscosity). This solution remained transparent and stable even when further diluted with diethylene glycol monoethyl ether to double the volume (solid content 25%). Also, the viscosity of a 50% solution of dipropylene glycol monomethyl ether is W3/4
It was stable and transparent. 500 g of the obtained polymer was dissolved in 500 g of diethylene glycol monoethyl ether by heating at 120°C.
After cooling to 50° C., 40 g of a 1/1 mixture of TPT/diethylene glycol monoethyl ether was added and mixed as a curing agent to prepare an insulating paint. The insulating paint had a viscosity of T3/4, a solids content of 45%, and remained stable and transparent even after being left for 6 months. The prepared insulating paint was coated and baked five times on an annealed copper wire with a diameter of 1 mm at a baking temperature of 45° C. and a wire speed of 6.5 m/min by a conventional method, and a good enameled wire was obtained. Comparative Example 1 This comparative example is an example of a conventional method in which CH:COOH=1.4:1, THEIC content is 50 equivalent %, and EG is used for the remaining 50 equivalent % of the hydroxy component. Reaction component grams (1) EG 195.3 (2) THEIC 549.0 (3) TPA 747.9 Reaction component (1) in 2 flasks similar to Example 1
~(3) was charged, and heating and temperature raising was started while stirring. The first distillate was obtained at 210°C. The reaction was continued by gradually raising the temperature and adjusting it to 235°C. When the reaction system obtained 157 c.c. of distillate, TPA crystals disappeared, the system became transparent, and the distillation rate decreased. At this point, the flask was flushed with nitrogen gas to remove an additional 8 c.c. of distillate, and the reaction product was removed from the flask. The viscosity of a 50% solution of the final polymer in diethylene glycol monoethyl ether was Z ₃ at 25°C. However, this solution is further diethylene glycol monoethyl ether.
When diluted to 1.1 times the volume (solid content 45%), it becomes cloudy,
When diluted to 1.25 times the volume (solid content 40%), a cloudy white separation occurred. Also, dipropylene glycol monomethyl ether is transparent at temperatures above 100℃, but at 50℃
When the mixture was cooled to a certain temperature, it became cloudy and separated. This is the solid content
The same result was obtained even when the ratio was set to 60%. 500 g of the obtained polymer was dissolved in 500 g of diethylene glycol monoethyl ether by heating at 120°C.
After cooling to 50 °C, TPT solution similar to Example 1
When 40 g was added and mixed, a gel-like substance was formed and became cloudy, and the mixture turned into a cloudy white paste at room temperature. Example 1
Unlike the conventional method, polyester had a small solvent tolerance with glycol ether, and it was not possible to prepare the desired insulating coating. Example 2 In this example, OH:COOH=1.5:1, THEIC
20 equivalent% of hydroxy component, content 60 equivalent%
This is an example of polyester and insulating paint synthesized using diethylene glycol monoisopropyl ether. Reaction component grams (1) EG 31.0 (2) Diethylene glycol monoisopropyl ether 148.2 (3) THEIC 261.3 (4) TPA 277.0 In a flask equipped with a stirrer, thermometer, distillation condenser and vacuum distillation device, Reaction components (1) to (4)
was charged, and heating and temperature raising was started while stirring. The temperature was raised to 200°C in 2 hours. The first distillate was obtained at 203°C. As the distillate was removed, the reaction temperature was gradually increased and the reaction was continued at a maximum of 235°C. When the distillate reached 55 c.c., the reaction system became transparent. When the distillate reached 65 c.c., the flask was evacuated and an additional 40 c.c. of distillate was removed at a temperature of 210° C. to complete the reaction, and the reaction product was taken out from the flask. The viscosity of a 50% solution of the final polymer in diethylene glycol monoisopropyl ether is V at 25°C.
It was 1/2. Even when this solution was further diluted to twice the volume (solid content 25%) with diethylene glycol monoisopropyl ether, it remained transparent and stable. 400 g of the obtained polymer was heated at 120°C in a mixed solvent of 200 g of diethylene glycol monobutyl ether and 200 g of diethylene glycol monoethyl ether, and after cooling to 50°C, the same TPT as in Example 1 was added.
A wire enamel was prepared by adding and mixing 32 g of the solution and 40 g of a 4.0% diethylene glycol monoethyl ether solution of meta,para-cresol-formaldehyde resin. The wire enamel had a viscosity of U3/4, a solids content of 45.2%, and remained stable even after being left at room temperature for 6 months. When this wire enamel was baked onto an annealed copper wire having a diameter of 1 mm in the same manner as in Example 1, a good enameled wire was obtained. Comparative example 2 In this comparative example, OH:COOH=1.5:1, THEIC
The remaining 40 equivalent% of the hydroxy component with a content of 60 equivalent%
is an example of the conventional method using EG. Reaction component grams (1) BG 62.0 (2) THEIC 261.3 (3) TPA 277.0 The reaction was carried out in the same flask as in Example 2. Reaction components (1) to (3) were charged, and the temperature was raised while stirring to obtain a first distillate at 212°C. The reaction temperature was gradually raised to 235°C and the reaction was continued. When the reaction system became transparent and 58 c.c. of distillate was obtained, the flask was depressurized and 6 c.c. of distillate was removed to complete the reaction, and the reaction product was taken out from the flask. . A 50% solution of the final polymer in diethylene glycol monoisopropyl ether was clear when heated, but became cloudy when cooled to room temperature, and further dissolved in diethylene glycol monoisopropyl ether.
When diluted to 1.1 times the volume (solid content 45%), a cloudy white separation occurred. 400 g of the obtained polymer was heated and dissolved in a mixed solvent of 200 g of diethylene glycol monobutyl ether and 200 g of diethylene glycol monoethyl ether at 120°C, but when it was cooled to below 50°C, it became cloudy.
It was not possible to adjust the insulation paint. Example 3 In this example, OH:COOH=1.65:1, THEIC
25 equivalents% of hydroxy component with a content of 55 equivalents%
This is an example of polyester and insulating paint synthesized using diethylene glycol monoethyl ether. Reaction component grams (1) EG 76.13 (2) Diethylene glycol monoethyl ether 414.6 (3) THEIC 592.5 (4) TPA 623.25 Into two flasks similar to Example 1, add reaction component (1).
~(4) was charged, and the temperature was raised while stirring. During the temperature increase to 210°C in 2 hours, the first distillate was obtained at 204°C. The reaction temperature was gradually raised to 235°C and the reaction was continued. When the reaction system becomes transparent and the distillate reaches 260 c.c., a large amount of nitrogen gas is introduced into the flask, and 100 c.c. of the distillate is removed to terminate the reaction and remove the reaction product. Removed from flask. The viscosity of a 50% dipropylene glycol monomethyl ether solution of the final polymer was T1/4 at 25°C. This solution remained transparent and stable even when diluted with dipropylene glycol monomethyl ether to 1.7 times its volume (solid content 30%). Furthermore, this polymer is easily soluble in diethylene glycol monoethyl ether and gradually dissolves even when left at room temperature, and the solvent tolerance range is so large that the resulting solution can be diluted infinitely with diethylene glycol monoethyl ether. It was hot. Next, 500 g of the obtained polymer was dissolved in 500 g of dipropylene glycol monomethyl ether by heating at 120°C, and after cooling to room temperature, the same procedure as in Example 1 was carried out.
An insulating paint was prepared by adding and mixing 40 g of TPT solution. The viscosity of this insulating paint was V at 25°C, and it remained transparent and stable even after being left for 6 months. When an annealed copper wire with a diameter of 1 mm was baked in the same manner as in Example 1, a good enameled wire was obtained. Comparative example 3 In this comparative example, OH:COOH=1.65:1, THEIC
This is an example of a conventional method in which EG is used for the remaining 45 equivalent % of the hydroxy component, which has a content of 55 equivalent %. Reaction component grams (1) EG 172.65 (2) THEIC 592.5 (3) TPA 623.25 Reaction component (1) in 2 flasks similar to Example 3
~(3) was prepared and reacted. The first distillate was obtained at 212°C. The temperature was gradually raised and adjusted to 235°C to continue the reaction. When the TPA crystals disappeared from the reaction system and it became transparent, and the distillate reached 140 c.c., a large amount of nitrogen gas was flowed into the flask, and an additional 20 c.c.
The reaction was completed by removing the effluent, and the reaction product was taken out from the flask. A 50% solution of the final polymer in dipropylene glycol monomethyl ether was transparent when heated, but it became cloudy at temperatures below 50°C, making it impossible to prepare an insulating paint. Example 4 In this example, OH:COOH=1.5:1, THEIC
This is an example of an insulating paint and a polyester synthesized using dipropylene glycol monomethyl ether for 10 equivalents of a hydroxy component with a glycerin content of 30 equivalents and a glycerin content of 30 equivalents. Reaction component grams (1) EG 62.0 (2) GL 46.0 (3) Dipropylene glycol monomethyl ether 73.0 (4) THEIC 131.0 (5) TPA 277.0 Reaction component (1) in the same flask as Example 2
~(5) was prepared and reacted. The first distillate is 204℃
The reaction temperature was gradually raised to 235°C. When TPA crystals disappeared from the reaction system and it became transparent, and the distillate amounted to 60 c.c., the flask was depressurized and an additional 15 c.c. of distillate was removed to complete the reaction. A 50% dipropylene glycol monomethyl solution of this polymer remained transparent and stable even when cooled to room temperature or below. This solution remained clear even when further diluted to 1.7 volumes (30% solids) with dipropylene glycol monomethyl ether. 400 g of the obtained polymer was heated and dissolved in 400 g of dipropylene glycol monomethyl ether at 120°C, cooled to 50°C, and 32 g of a 1/1 mixture of TBT/diethylene glycol monoethyl ether was added and mixed to obtain an insulating paint. . An annealed copper wire having a diameter of 1 mm was baked in the same manner as in Example 1 to obtain a good enamelled wire. Comparative Example 4 In this comparative example, OH:COOH=1.5:1, THEIC
This is an example of a conventional method in which EG is used for the remaining 40 equivalent % of the hydroxy component, which has a glycerin content of 30 equivalent % and a glycerin content of 30 equivalent %. Reaction component grams (1) EG 62.0 (2) GL 46.0 (3) THEIC 131.0 (4) TPA 277.0 Reaction component (1) in the same flask as Example 2
~(4) was prepared and reacted. The first distillate is 200℃
The reaction temperature was gradually raised to 235°C. When the TPA crystals disappeared and the reaction system became transparent and the distillate amounted to 58 c.c., the flask was depressurized and an additional 5 c.c. of the distillate was removed to complete the reaction. The resulting 50% dipropylene glycol monomethyl ether solution of the polymer was transparent when heated, but became cloudy when cooled to around 50°C.
It was not possible to prepare an insulating paint. Example 5 In this example, OH:COOH=1.73:1, THEIC
7 equivalent% of hydroxy component with a content of 50 equivalent%
This is an example of polyester and insulating paint synthesized using diethylene glycol monomethyl ether. Reaction component grams (1) EG 143.94 (2) Diethylene glycol monomethyl ether 80.0 (3) THEIC 484.0 (4) TPA 555.3 Into two flasks similar to Example 1, add reaction component (1).
~(4) was prepared and reacted. The first distillate was obtained at 206°C and the reaction temperature was gradually increased and adjusted to 235°C.
When the distillate reached around 120c.c., the TPA crystals disappeared from the reaction system and it became transparent. When the distillate reached 130 c.c., a large amount of nitrogen gas was introduced into the flask, and further
The reaction was terminated by removing 10 c.c. of distillate. The viscosity of a 50% solution of the final polymer in diethylene glycol monoethyl ether was U at 25°C. 500 g of the obtained polymer was dissolved in 500 g of diethylene glycol monoethyl ether by heating at 120°C, and after cooling to 50°C, 40 g of the same TPT solution as in Example 1 and 40 g of a 50% diethylene glycol monoethyl ether solution of Desmodeur CT stable were added. , and 50 g of a 40% diethylene glycol monoethyl ether solution of meta-, para-cresol-formaldehyde resin.
They were added and mixed to prepare an insulating paint. The viscosity of this enamel is V ⁺ and the diameter 1
When baked on mm annealed copper wire, a good enamelled wire was obtained. Table 1 shows the characteristics of the enamelled wire coated with the insulating paint obtained in each example.

[Table] As is clear from Examples, Comparative Examples, and Table 1, the obtained polyester is stably soluble in glycol ether, and when prepared into the insulating coating of the present invention, the enameled wire has excellent heat resistance properties. , F~H
It can be fully used as a class-class heat-resistant, low-pollution insulating paint.

Claims (1)

[Scope of Claims] 1. The ratio of hydroxy group equivalent to carboxyl group equivalent is within the range of 1.3:1 to 2:1, and the hydroxy group by tris(2-hydroxyethyl) isocyanurate is 30 equivalent% or more and General formula RO(-C _o H _2o O) - _x H (wherein, R is an alkyl group or phenyl group having 1 to 6 carbon atoms, n is 2 or 3, and x is 1 to 3 carbon atoms) ) of the monoalkyl or monophenyl ether of the alkylene glycol of the polyester which is a polycondensate of a hydroxyl component containing 5 to 30 equivalents of hydroxyl groups and dicarboxylic acid. Electrical insulation paint made from enyl ether solution. 2 R is an alkyl group having 1 to 4 carbon atoms,
The electrically insulating paint according to claim 1, wherein x is 2 or 3. 3. The electrically insulating paint according to claim 1, wherein R is a phenyl group. 4 The hydroxyl group due to tris(2-hydroxyethyl) isocyanurate is 40 to 80 equivalent%, and the hydroxyl group due to monoalkyl or monophenyl ether of alkylene glycol is
The electrically insulating paint according to any one of claims 1 to 3, which has a content of 10 to 25 equivalent %. 5. The electrically insulating paint according to any one of claims 1 to 4, wherein the monoalkyl or monophenyl ether solution of alkylene glycol of polyester contains a curing agent. 6. The electrically insulating paint according to claim 5, wherein the curing agent is a titanate.