JP2585685B2 - Heat resistant electrical insulation paint - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-resistant electrical insulating paint used for electrical insulation and for coating electric wires.

[Conventional technology]

A polyester resin or polyesterimide resin-based electric insulating paint using tris-2-hydroxyisocyanurate as a polyhydric alcohol component forms a coating film having excellent heat resistance, electric insulating properties, and the like. Insulated wires baked with this type of paint are widely used in consumer appliances and the like due to the advantages of heat resistance, electrical insulation, and mechanical properties with the downsizing of instruments. However, the coated electric wire baked with the paint has a disadvantage that when exposed to a high temperature in the air, the coating is deteriorated due to oxidation and the breakdown voltage resistance is significantly reduced. For this reason, conventionally, a method has been adopted in which second and third resins having radical scavenging properties, such as a phenol resin and a melamine resin, are added to an electric insulating paint to delay the oxidative deterioration in the air.

[Problems to be solved by the invention]

However, according to the method described above, the oxidation deterioration of the coating can be delayed, but the flexibility and the reciprocal wear resistance of the coated electric wire due to the hard and brittle properties of the second and third resins themselves. This leads to a remarkable decrease in adhesion to the conductor.

The present invention has been made in view of such circumstances,
The object of the present invention is to provide a heat-resistant electrically insulating paint which does not impair the mechanical properties such as flexibility, abrasion resistance and adhesion of the film, and which does not cause a decrease in breakdown voltage resistance due to coating deterioration due to oxidation. And

[Means for solving the problem]

In order to achieve the above object, a heat-resistant electric insulating paint according to the present invention is a polyester resin or a polyesterimide resin containing a structural portion derived from a polyhydric alcohol component, tris-2-hydroxyisocyanurate, in a molecular skeleton. A part of the hydroxyl groups of the following general formula (I)
Is esterified with tetrahydrophthalimidic acid represented by the formula:

[R is a divalent organic group. [Operation] That is, the present inventors have conducted research on development of a method capable of sufficiently maintaining the breakdown voltage resistance after oxidative degradation without impairing the heat resistance and mechanical properties of the coating film. As a result, a part of the hydroxyl group of the polyester resin or the polyesterimide resin having a structural portion derived from the polyhydric alcohol component tris-2-hydroxyisocyanurate in the molecular skeleton is represented by the above-mentioned general formula (I). It has been found that the intended purpose can be achieved by esterification with tetrahydrophthalimidic acid.

The heat-resistant electric insulating paint of the present invention is obtained by using a polyester resin or a polyesterimide resin containing a structural portion derived from tris-2-hydroxyisocyanurate in a molecular skeleton, and tetrahydrophthalimidic acid. is there.

The polyester resin or polyesterimide resin is obtained by a conventionally known method using a polyhydric alcohol and a polybasic acid.

As the polyhydric alcohol, tris-2-hydroxyisocyanurate (hereinafter abbreviated as "THEIC") is used as a trihydric alcohol together with other polyhydric alcohol components such as ethylene glycol.

The above-mentioned tetrahydrophthalimidic acid is represented by the above formula (I)
And obtained by using, for example, tetrahydrophthalic anhydride and aminocarboxylic acid.

Examples of the aminocarboxylic acid include glycine, glutamic acid, paraaminobenzoic acid, and metaaminobenzoic acid.

As described above, the tetrahydrophthalimidic acid represented by the general formula (I) is synthesized using tetrahydrophthalic anhydride and the above-mentioned aminocarboxylic acid, and equimolar amounts of both components at a temperature of 150 to 200 ° C. It is easily synthesized by reacting. In the general formula (I),
R is Or -CH _2- is preferred in terms of more effectiveness.

The tetrahydrophthalimidic acid thus obtained reacts with a hydroxyl group of a polyester resin or a polyesterimide resin containing a structural portion derived from the polyhydric alcohol component THEIC in the molecular skeleton to form an ester bond. In this case, it is preferable to form an ester bond with 10 to 30% of the total number of hydroxyl groups of the resin. That is, if the esterification is less than 10% of the total number of hydroxyl groups, the effect of improving the breakdown voltage after oxidative degradation is not seen, and if it exceeds 30%, the breakdown voltage after oxidative degradation is sufficiently maintained. However, this is because a decrease in the number of crosslinking points in the resin causes a problem that the coating film becomes soft and the heat softening temperature is lowered.

The heat-resistant electric insulating paint of the present invention can be produced using the above-mentioned raw materials, for example, as follows.
That is, first, tetrahydrophthalimidic acid is synthesized in advance as described above, and this is added to a polyester resin or polyesterimide resin melted at a temperature of 120 ° C. or higher, and a reaction is performed at a temperature of 150 to 230 ° C. for 2 to 3 hours. . Then, the reaction is completed when water in the dehydration condensation reaction is distilled off. Next, the resin thus obtained is diluted with a conventionally known solvent such as cresol and naphtha, and then added with a conventionally known crosslinking agent such as tetrapropyl titanate and tetrabutyl titanate to form a coating. Can be manufactured.

In the production of the paint, a phenolic resin that has been widely used in the past for the purpose of improving the paintability of the paint,
Thermosetting resins such as melamine resin, urethane resin and polyamide resin, and organic metal dryers such as tin octenoate, zinc octenoate, tin naphthenate and zinc naphthenate do not impair the properties of the heat-resistant electrically insulating paint of the present invention. You may add in the range.

〔The invention's effect〕

As described above, the heat-resistant electric insulating paint of the present invention has a part of the hydroxyl group of a polyester resin or a polyesterimide resin containing a structural part derived from THEIC which is a polyhydric alcohol component in a molecular skeleton. Since it is esterified with tetrahydrophthalimidic acid represented by the general formula (I), it does not impair the mechanical properties such as flexibility, abrasion resistance and adhesion of the coating film, and has a breakdown voltage after oxidative deterioration. Sex can be maintained.

 Next, examples will be described together with comparative examples.

First, tetrahydrophthalimidic acid was synthesized as follows.

<< Method A for producing tetrahydrophthalimidic acid >> In a reaction vessel equipped with a stirrer, a thermometer and a condenser, 304 g (2.0 mol) of tetrahydrophthalic anhydride and 150 g (2.0 mol) of glycine are gradually heated, and the reaction product water is distilled off. While reacting at a temperature of 150-160 ° C for 2 hours
272 pale yellow crystals were obtained (THEIC-A).

{Method B for producing tetrahydrophthalimidic acid} N-methylpyrrolidone 542 g is placed in the same reaction vessel as in Preparation A.
(5.47 moles), 304 g (2.0 moles) of tetrahydrophthalic anhydride and 274 g (2.0 moles) of paraaminobenzoic acid were added, and the temperature was gradually raised.
After reacting for 3 hours, a large amount of water was added to the reaction solution to precipitate a product, which was washed several times with methanol.
After drying under reduced pressure for a time, a yellow powder having an acid value of 210 was obtained (THEIC-
B).

 Next, a resin composition was prepared as follows.

<< Preparation C >> In a four-necked flask equipped with a condenser containing glass beads with a moisture meter, a thermometer and a stirrer, 664 g (4.0 mol) of terephthalic acid and 223.3 g of ethylene glycol
(3.6 moles), 991.8 g (3.8 moles) of THEIC and 0.27 g of dibutyltin dilaurate were charged and heated with stirring. When the temperature was raised to 180 ° C. in one hour, water was distilled. Furthermore, the temperature was raised from 180 ° C. to 230 ° C. over 6 hours, and the reaction was carried out for 3 hours. As a result, 148 g of water containing a part of glycol was distilled off, and a resin having an acid value of 14.6 was obtained. Next, 640 g of cresol was added to the above resin, the temperature was cooled to 130 ° C., and 316.8 g (1.6 mol) of diaminodiphenylmethane and 614.4 g (3.2 mol) of trimellitic anhydride were added thereto.
When the temperature was raised to 20 ° C. over 2 hours and the reaction was carried out for 4 hours, 120 g of water partially containing cresol was distilled off, and a brown transparent resin solution was obtained. This resin solution has an acid value of 9.8,
It had a softening point of 102 ° C. and a hydroxyl value of 132 (resin C).

<< Preparation D >> In the same flask as Preparation C, 664 g of terephthalic acid (4.0
Mol), ethylene glycol 198.4 g (3.2 mol), THIEC6
78.6 g (2.6 mol) and dibutyltin dilaurate 0.27
g, the same operation as in Preparation C was carried out. As a result, 146 g of water containing a part of glycol was distilled off, and the acid value was 16.8 and the softening point was 78 ° C.
A colorless and transparent resin was obtained. Next, the above resin was cooled to 210 ° C. and further reacted for 1 hour at a reduced pressure of 720 mmHg. As a result, a resin having an acid value of 6.7, a softening point of 108 ° C. and a hydroxyl value of 110 was obtained (resin D).

Example 1 300 g of the resin C obtained in Preparation C was charged into a one-necked four-necked flask equipped with a stirrer, a thermometer, and a condenser. Furthermore, TEHIC-A3
When 6.5g was added and the reaction was carried out at 180 ° C for 2 hours,
A brown transparent resin solution having an acid value of 8.6 and a hydroxyl value of 89.4 was obtained.
To this resin solution was added 154 g of cresol, and after cooling to 150 ° C., 102 g of Naphtha II was added for dilution. Next, the diluted resin solution was cooled to 60 ° C., and a mixed solution of 8.2 g of tetrabutyl titanate and 24.0 g of cresol was added dropwise over 30 minutes.
A heat-resistant electrically insulating paint having a viscosity of 55.2 poise (30 ° C.) and a viscosity of 45.2% (200 ° C., 2 hours) was obtained.

Example 2 300 g of the resin C obtained in Preparation C was charged into one four-necked flask equipped with a stirrer, a thermometer and a condenser, heated to 130 ° C. and stirred. Furthermore, TEHIC-B2
After adding 8.5g and reacting for 2 hours at a temperature of 200 ° C,
A brown transparent resin solution having an acid value of 7.6 and a hydroxyl value of 103 was obtained.
144 g of cresol was added to this resin solution, and after cooling to 150 ° C., 98 g of Naphtha II was added for dilution. Next, the diluted resin solution was cooled to 60 ° C., and a mixed solution of 8.0 g of tetrabutyl titanate and 24.0 g of cresol was added dropwise over 30 minutes.
A heat-resistant electrically insulating coating material having a viscosity of 46.7% (30 ° C) and a viscosity of 46.7% (200 ° C, 2 hours) was obtained.

Example 3 A light yellow transparent resin solution having an acid value of 6.0 and a hydroxyl value of 88.2 was obtained in the same manner as in Example 1 except that 300 g of Resin D and 18.8 g of THEIC-A obtained in Preparation D were used. After 380 g of cresol was added to the resin solution for dilution, the mixture was cooled to a temperature of 60 ° C., and a mixed solution of 9.5 g of tetrabutyl titanate and 30.0 g of cresol was added.
Drop over 0 minutes, 15.5% red-brown transparent ester,
Non-volatile content 43.3% (200 ° C, 2 hours), viscosity 38.6 poise (30
C.) was obtained.

Example 4 300 g of the resin D obtained in Preparation D was charged into one four-necked flask equipped with a stirrer, a thermometer, and a condenser, heated to 130 ° C., and stirred. Furthermore, TEHIC-
After adding 40.6 g of B, the mixture was reacted at a temperature of 220 ° C. for 3 hours to obtain a brown transparent resin solution having an acid value of 5.1 and a hydroxyl value of 72.9. Add 410 g of cresol to this resin solution, dilute, and add
Cooled down. Next, a mixed solution of 10 g of tetrabutyl titanate and 30 g of cresol was added to the diluted resin solution.
Drop over 30 minutes, 25.8 red-brown transparent esterification
%, A nonvolatile content of 43.6% (200 ° C., 2 hours) and a viscosity of 41.0 poise (30 ° C.) were obtained.

[Comparative Example 1] 600 g of the resin C obtained in Preparation C was charged into a two-necked flask equipped with a stirrer, a thermometer, and a condenser, and heated to 130 ° C.
48 g and 176 g of Naphtha II were added to dilute and cooled to 60 ° C. Next, a mixed solution of 14.4 g of tetrabutyl titanate and 42.0 g of cresol was added dropwise to the diluted resin solution at a temperature of 60 ° C. over 30 minutes, and a red-brown transparent nonvolatile content of 45.1%
(200 ° C., 2 hours), a heat-resistant electric insulating paint having a viscosity of 49.8 poise (30 ° C.) was obtained.

[Comparative Example 2] A resol type phenol resin (Resitop PL-24, manufactured by Gunei Chemical Co., Ltd.) was added to 540 g of the heat-resistant electric insulating paint obtained in Comparative Example 1.
75) 33.6 g was added to obtain an electrically insulating paint.

[Comparative Example 3] 600 g of the resin D obtained in Preparation D was charged into a two-necked four-necked flask equipped with a stirrer, a thermometer and a condenser, and the temperature was raised to 150 ° C.
It was diluted by adding 40 g, and cooled to 60 ° C. Next, a mixed solution of 18 g of tetrabutyl titanate and 55 g of cresol was added dropwise to the diluted resin solution at a temperature of 60 ° C. over 30 minutes, and a red-brown transparent nonvolatile matter of 43.3% (200 ° C., 2 hours) and a viscosity of 42.0% A poise (30 ° C.) heat-resistant electrically insulating paint was obtained.

[Comparative Example 4] The resole type phenol resin (Resitop PL-24, manufactured by Gunei Chemical Co., Ltd.) was added to 706 g of the heat-resistant electric insulating paint obtained in Comparative Example 3.
75) 42 g was added to obtain an electrically insulating paint.

Next, the obtained example product and comparative product were furnace length 5 m.
The wire was baked on the outer periphery of the wire using a vertical furnace at a temperature of 450 ° C. and a take-up speed of 15 m / min, and a characteristic test of the obtained electrically insulated wire was performed according to JIS C-3210. The results are shown in the table below.

As is clear from the above table, the breakdown voltage of the example product in the initial state is not different from that of the comparison product, but the reduction of the breakdown voltage at high temperature and for a long time is suppressed. It can be seen that the example products are excellent in breakdown voltage resistance after oxidative deterioration.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08G 73/16 NTK C08G 73/16 NTK NTM NTM

Claims (3)

(57) [Claims] 1. A polyester resin or a polyesterimide resin having a structural portion derived from tris-2-hydroxyisocyanurate which is a polyhydric alcohol component in a molecular skeleton, and a part of the hydroxyl groups is represented by the following general formula ( A heat-resistant electrically insulating paint characterized by being esterified with tetrahydrophthalimidic acid represented by I). [R is a divalent organic group. ] 2. The esterification with tetrahydrophthalimide acid is set to 10 to 30% of the total number of hydroxyl groups of the polyester resin or polyesterimide resin.
The heat-resistant electrical insulating paint as described. (3) R in the tetrahydrophthalimide acid represented by the general formula (I) is Or -CH ₂ - in which according to claim 1 or 2, wherein the heat-resistant electrically insulating coating.