JPS5811907B2 - Manufacturing method of paint for electric wires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing a paint for electric wires, and more specifically, the present invention relates to a method for producing a novel paint for electric wires, and more specifically, 1.2.3.4 to butanetetracarboxylic acid (hereinafter referred to as B
TC) and diamine in a single or mixed solvent of polyhydric alcohol, polyhydric alcohol derivative, ketone, ether, and ester.
The present invention relates to a method for producing a paint for electric wires, characterized in that an ammonium salt is formed in ~30% of a polyimide precursor such that the amount of water in the total solvent is 20% by weight or less.

Polyimides made from BTC and polyamines are well known as shown in Japanese Patent Publication No. 48-2238, Japanese Patent Publication No. 47-14503, etc., and polymers with excellent heat resistance can be obtained and are useful, for example, as films or as electrical insulation paints. It is.

In these inventions, relatively strong polar solvents such as N-methyl 2-pyrrolidone, dimethylacetamide, and phenolic solvents are used as solvents, or they are made into water-soluble forms that take advantage of the properties of polymer electrolytes. There is.

In recent years, environmental pollution issues such as air pollution have become more important, and nitrogen-containing solvents and phenolic solvents such as those mentioned above are used to prevent pollution and to prevent irritation and odor if they come into contact with the human body. Therefore, I tend to avoid it if possible.

As a solution to this problem, so-called water-soluble polyimides, in which these polymers are dissolved in water, have been proposed, but these also have some problems.

For example, there are problems with combustion of solvents when used as wire coatings.

In recent years, in the production of enameled wire, so-called catalytic combustion hot air circulation firing ovens have been widely used, which burn the organic solvent in the paint using a catalyst and use the combustion heat generated at that time as energy for curing the paint film. It has become.

Water-soluble paints are not suitable for these catalytic combustion baking furnaces because they cannot burn water.

This point is one of the drawbacks in industrial use of water-soluble paints.

In addition, water evaporates more easily at room temperature than amine solvents or phenolic solvents, and as a property of polymer electrolytes, viscosity is highly dependent on concentration, so the viscosity of the solution changes during use. It is relatively large and may be inconvenient to handle.

There are other points to consider, such as an increase in drying energy due to the large latent heat of vaporization and consideration for corrosion of the equipment.

On the other hand, BTC-based polyimides dissolved in relatively harmless organic solvents such as alcohols, ketones, and ethers are described in Japanese Patent Publications No. 45-32716 and No. 46-22937.

However, these are monomers or low molecular weight condensates in a solution state, and are subject to certain practical limitations when used industrially.

For example, when used as a paint for electric wires, it is difficult to obtain a uniform coating surface, and therefore the original performance may not be exhibited in terms of mechanical, electrical, or thermal properties.

In addition, resins with a relatively high degree of condensation are
Even if you try to dissolve it in common solvents such as alcohols, ketones, and ethers as shown in Japanese Patent Publication No. 46-22937, most of them become cloudy and it is difficult to make a homogeneous solution. Therefore, the storage stability of the solution and There are difficulties in workability when using it as an electric wire paint.

The present invention eliminates the above-mentioned drawbacks and provides thermal, mechanical, electrical,
The present invention provides a paint for electric wires with excellent chemical properties.

That is, the present invention combines BTC or a derivative thereof (anhydride, dianhydride, ester, amide, etc.) and diamine with alcohol, polyhydric alcohol, polyhydric alcohol derivative ketone, ether, and ester. A polyimide precursor with an acid value residual rate of 3 to 30% obtained by reacting in a general solvent such as alone or in a mixed system, and ammonium The present invention relates to a paint for electric wires characterized by forming a salt.

The reaction between BTC and diamine is carried out in a single or mixed solvent selected from the group of alcohols, polyhydric alcohols, polyhydric alcohol derivatives, ketones, ethers, and esters, but the reaction in the absence of a solvent is also the gist of the present invention. This does not deviate from the above, and even in the case of a reaction without a solvent, a solution with the same properties can be obtained by dissolving the obtained polyimide precursor in the above-mentioned solvent.

The reaction temperature is 60-230°C, preferably 80-200°C.

The molar ratio of BTC and diamine is preferably equimolar, but there is no particular problem even if one or the other is in excess of several moles.

There is no particular restriction on the concentration during the reaction of BTC and diamine, but
Reactions without a solvent or at high concentrations are not necessarily effective in obtaining a homogeneous solution, and are uneconomical at low concentrations.
Concentrations of 0-70% are effective.

The degree of progress of the reaction can be determined by measuring the amount of water produced as a by-product, but more preferably by measuring the acid value.

The residual acid value at the end of the reaction varies slightly depending on the intended use of the product and the concentration at the time of reaction, but is usually 3 to 30%, more preferably 5 to 20%.

Here, the acid value means the mg equivalent of carboxyl groups per 1 g of sample, and the acid value residual rate refers to how many acid groups remain after the reaction, assuming the acid value of the sample before starting the reaction as 100%. shows.

In this case, the sample refers to the entire solution including the solvent.

When the acid value residual rate is 30% or more, the obtained polymer has relatively good solubility in solvents, but when this is used as a coating for electric wires, the surface appearance of the coating film tends to be uneven. Furthermore, it is insufficient in mechanical properties such as flexibility, and is difficult to use in practice.

The higher the degree of condensation and the lower the acid value by increasing the imidization by ring closure of the amic acid, the lower the solubility in the above-mentioned solvent will be, and if it becomes cloudy and insoluble at room temperature, it will become pasty.

This is extremely inconvenient in terms of handling when used as a paint.

On the other hand, it has been found that baked coatings made of polymers with lower acid values that have undergone more reaction are superior in terms of surface appearance and properties.

The present inventors focused on these two contradictory factors and, as a result of intensive study, found that even resin solutions with low acid value and prone to turbidity,
By reacting ammonia in the presence of a small amount of water, we succeeded in obtaining a clear solution with excellent storage stability.

The amount of water used here must be such that the paint for electric wires of the present invention is not harmful during actual use.

The most important reason for limiting the amount of water is that when the paint containing the ammonium salt of the polyimide precursor in the present invention is applied to a catalytic firing oven, water has a negative effect on the combustion of the solvent. This is because it must be done.

Usually, the amount of water is preferably 20% by weight or less of the total amount of solvent, including water.

It is more effective to add this water in the form of aqueous ammonia than to add it intentionally, but there is no particular problem in adding water and ammonia separately.

As an example of how the solubility of the polyimide precursor solution can be further enhanced by using ammonia as a neutralizing agent, for example, an acid value residual rate of 19% obtained by reacting in a polyhydric alcohol at a concentration of 50% is given. The polyimide precursor solution is transparent when heated and opaque at room temperature, but
By adding aqueous ammonia to this system, it becomes a transparent solution even at room temperature and has good storage stability.

Here, it is thought that ammonia not only acts on the remaining carboxyl groups of the polyimide precursor, but also acts on the carboxyl groups produced by re-decomposing the imide groups after ring closure depending on the addition temperature.

The properties of the cured polymer of solutions to which ammonia has been added in this way are almost incomparable with those of highly condensed polymers synthesized by other methods, for example from BTC and diamines in N-methyl-2-pyrrolidone solvent. Nothing has changed.

When adding ammonia water, it can be added directly to the precursor solution, but alcohol, polyhydric alcohol,
It may be added by mixing with a solvent such as a polyhydric alcohol derivative, ether, ketone, or ester.

It was found that the electric wire paint thus obtained did not have an ammonia odor and did not emit any odor during the baking process.

The reason is that after adding ammonia to the solution, the temperature
This is thought to be because excess ammonia is removed from the system by heating and stirring at a temperature of .

In the formation of the polyimide precursor in the present invention, BTC is basically used as the acid component, but the amine component is not particularly limited, and includes aliphatic, alicyclic,
Although aromatic amines can be used as appropriate, aromatic diamines are more practical.

Examples of these are m-phenylenediamine, p-
Phenylene diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4.4'
Diaminodiphenylpropane, 4.4'-diaminodiphenyl ether, 3.4'-diaminodiphenyl ether, benzidine, 3.4'-dimethylbenzidine, 4.
4'-diaminodiphenylsulfide, 4.4'-diaminodiphenylsulfone, 3.3'-diaminodiphenylsulfone, m-bis(4-aminophenoxy)benzene, p-bis(4-aminophenoxy)benzene, 4.
4'-diaminobiphenyl, m-xylylenediamine,
p-xylylenediamine, di(p-aminocyclohexyl)methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4.4'-dimethylheptadiamine, 3-methoxyheptamethylenediamine, 2.11 -diaminododecane, 1.4-diaminocyclohexane, 2.2'-diaminodiethyl ether, 2.2'-diaminodiethylthioether, 3.3'-diaminodipropoxyethane,
2.6-diamitupyridine, guanamine, 2.5-diamino-1,3,4-oxadiazole, 2-(3'-aminophenyl)-5-aminebenzoxazole, bis-(4-aminophenyl) Phosphine oxyto, bis-
(4-aminophenyl)diethylsilane, etc., and these may be used alone or in combination.

As described above, the solvent used in the present invention is characterized in that it is selected from the group of alcohols, polyhydric alcohols, polyhydric alcohol derivatives, ethers, ketones, and esters.

Examples of these solvents include methanol, ethanol,
Propertool butanol, amyl alcohol, hexanol, octatool, cyclohexanol, methylcyclohexanol, dioxane, ethylene glycol, methyl cellosolve, methyl cellosolve acetate, ethyl cellosolve, cellosolve acetate, ethylene glycol isopropyl alcohol, ethylene glycol monobutyl ether, butyl cellosolve, di Butyl cellosolve, butyl cellosolve acetate, diethylene glycol, methyl carpitol, ethyl carpitol, butyl carpitol, diethylene glycol dimethyl ether,
Dibutyl calpitol, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol, glycerin, glycerin monoacetate, methyl propyl ketone, These include methyl butyl ketone, methyl amyl ketone, dipropyl ketone, diacetone alcohol, isophorone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, amyl acetate, and the like, and these can be used alone or in combination.

It goes without saying that these solvents can be used not only for reactions but also as diluents when diluting a solution as appropriate depending on the purpose.

It is also effective to add additives such as phenol resin, cresol resin, xylenol resin, melamine resin, titanium chelate compound, zircon chelate compound, etc. to the ammonium salt solution of the polyimide precursor obtained by the present invention.

Examples of the present invention will be described below.

Example 1 50 with thermometer, condenser with trap and stirrer
59.4 g (0.3 mol) of 4.4'-diaminodiphenylmethane and 130 g of triethylene glycol were placed in 14 0m2 flasks and heated to 60°C.

The system turned pale yellow and transparent. Then, at the same temperature, BTC70.2
g (0.3 mol) was added.

The temperature was gradually raised while stirring, and in the process the system became brownish turbid and became paste-like, but at 115°C it turned into a transparent solution.

The temperature was further increased and the reaction was continued at 140-150°C for 40 minutes.

It was observed that this amount of water was produced as a by-product.

The reaction system remained transparent even when cooled to room temperature, but when it was further heated and reacted at 160-170°C for about 1 hour, it became opaque when cooled to room temperature, indicating that the resulting resin was insoluble. .

This was a resin system with an acid value residual rate of 10.4%.

To this was added 8 g of commercially available 28% concentration ammonia water, 40 g of ethylene glycol, and 30 g of triethylene glycol, and the mixture was stirred at 80 to 90° C. for 1 hour.

The solution thus obtained was clear and had a non-volatile content of 36.7% (1
, 5g weighed, heated at 200°C for 2 hours) and had a viscosity of 15.8 poise (30°C).

Using a vertical furnace with a furnace length of 3 m, this solution was baked onto a copper wire with a wire diameter of 1 mmφ at a temperature of 430°C and a linear speed of 4.5 m/min using a conventional method. The performance of the enameled wire was as follows. It was found to have excellent mechanical, thermal, electrical, and chemical properties.

Finished film ring: 0.042mm Flexibility (self-diameter winding after 15% stretching): Good reciprocating abrasion resistance (
700g load): 93 times Thermal shock resistance (250℃ x 2 hours): Good self-warping wrapping Thermal softening temperature (1 point intersection 2.1Kg load, 2℃/min temperature increase): 4
41°C Deterioration resistance winding property (200°C x 24 hours): Good winding property with self-degradation (42A current, 20 seconds on, 10 seconds o
ff) Near 7 cycle dielectric breakdown voltage (normal state, 2 wires twisted state): 12.6KV same
(After treatment at 240℃ x 168 hours): 10.7KV Chemical resistance (H2SO4SG1.2, 23℃ x 24 hours treatment) Near H or above Same (NaOH 1%, same as above): 5H Solvent resistance (Penzol 23℃ x 24 hours Immersion) Near H or higher The electric wire paint according to Example 1 was tested in a catalytic combustion type hot air circulation baking furnace (manufactured by Daido Steel Co., Ltd.) and was found to be fully applicable.

Furthermore, this paint did not have an ammonia odor, and when it adhered to the human body, it did not exhibit any inflammatory properties as seen with cresol or N-methyl-2-pyrrolidone-based electric wire paints.

Example 2 In the same manner as in Example 1, butylcarpitol was used as a solvent.

The resulting resin solution was opaque and had a residual acid value of 14.2%.

A mixture of 70 g of ethylene glycol and 12 g of commercially available 28% ammonia water was added to this system, and the mixture was heated to 80-90°C.
Stir for hours.

The solution thus obtained was clear and had a non-volatile content of 35.2% (1
, 5g weighed, after heating at 200°C for 2 hours), and the viscosity was 7.9 poise (30°C).

This solution was baked on a 1 mm diameter copper wire under the same conditions as in Example 1.
The performance of m) was as follows.

Flexibility (self-diameter winding after 15% stretching): Good reciprocating wear resistance (
700g load): 86 times thermal shock resistance (250℃ x 2 hours): Good self-winding thermal softening temperature (1 point intersection, 2.1Kg load, 2℃/min temperature increase):
437°C Deterioration resistance (200°C x 24 hours): Good self-winding Breakdown voltage (normal state, 2 burn state): 13.5KV same
(After treatment at 240℃ x 168 hours): 11.2KV Chemical resistance (H2SO4SG1.2, 23℃ x 24 hours treatment) Near H or higher (NaOH 1% Same as above): 4H Solvent resistance (Penzol, 23℃ x 24 hours) immersion) Near H
Same as above (Dolol/Eratol = 7/3, same as above) Near H or above Example 3 30 with thermometer, cooler with trap and stirring device
m-phenylenediamine 32.0m in 14 flasks.
4 g (0,3 mol) and triethylene glycol 68
g was taken and heated to 60°C.

Then, 70.2 g (0.3 mol) of BTC was added at the same temperature.

The temperature was gradually raised while stirring, and in the process the system became brownish turbid and became paste-like, but at 118°C it turned into a transparent solution.

Next, as a result of reacting at 120 to 160°C for 3 hours, the acid value residual rate was 9.9%.

The solution became opaque upon cooling to room temperature, indicating that the resulting resin was insoluble.

To this system, 45 g of triethylene glycol, 40 g of diethylene glycol monomethyl ether and 28% of commercially available
Add a mixed bath of 10g of concentrated ammonia water and heat to 80-90℃
The mixture was heated and stirred for 1 hour.

The solution thus obtained was clear and had a non-volatile content of 38.4% (1
, 5g weighing, after heating at 200°C for 2 hours), viscosity 12.4
poise (30°C), and no ammonia odor was observed in the solution.

This solution was baked on a 1 mm diameter copper wire in the same manner as in Example 1.
The performance of m) was as follows.

Flexibility (with double diameter winding after 20% stretching): Good reciprocating wear (7
00g load) Near 3 times thermal shock resistance (250℃ x 2 hours): Good self-recovery thermal softening temperature (1 point crossing, 2.1Kg load, 2℃/min temperature increase):
448℃ Dielectric breakdown voltage (normal state, 2-piece twisted state): 12.7KV
(After treatment at 240℃ x 168 hours): 11.3KV Chemical resistance (H2SO4SG1.2, 23℃ x 24 hours treatment) Near H or higher (NaOH 1% Same as above): 4H Solvent resistance (Penzol, 23℃ x 24 hours) immersion) Near H
Above Example 4
117.0 g (0.5 mol) of BTC, 99.0 g of 4.4'-diaminodiphenylmethane in 14 0m flasks.
(0.5 mol) and 70 g of dipropylene glycol were added and stirred with heating.

Distillation of water started around 110°C, and the reaction system became a uniform dark brown solution.

Further heating and stirring were continued to raise the reaction temperature to 140°C.

During this time, the system gradually thickened and the reaction distillate amounted to 16 ml.

The acid value was 1.38 mg equivalent per 1 g of solution, and the acid value residual rate was 19.7%.

It became opaque upon cooling to room temperature.

A solution prepared by dissolving 20 g of commercially available 28% ammonia water in 50 g of dipropylene glycol was dropped onto the resin solution of the polyimide precursor obtained in this manner at 80 to 90°C, and 1
Stir for hours.

Ethylene glycol was added to adjust the viscosity, and a solution with a nonvolatile content of 34.1% (weighed 1.5 g, after heating at 200°C for 2 hours) and a viscosity of 32.3 poise (30°C) was finally obtained.

As a result of baking this solution onto a copper wire with a wire diameter of 1.0 mm in the usual manner under the same conditions as in Example 1, the performance of the enameled wire was as follows: mechanical, thermal, electrical, chemical It was found to have excellent properties.

Finished film thickness: 0.043mm Flexibility (self-diameter winding after 15% stretching): Good reciprocating wear resistance (
700g load): 88 times Thermal shock resistance (250℃ x 2 hours): Good self-winding Thermal softening temperature (2,1 ~ load): 430℃ Degradation resistance winding (200℃ x 24 hours): Self-winding Good punn-out characteristics (42A current, 20 seconds on, 10 seconds o
f): 85 cycles dielectric breakdown voltage (normal state, 2 strands twisted): 12.6KV
(After treatment at 240℃ x 168 hours): 9.7KV H2SO4 resistance (SG 1.2, 23℃ x 24 hours) Near H or higher NaOH resistance (5%, immersion at 23℃ x 24 hours): H Penzole resistance ( 23℃ x 24 hours immersion) Near H or higher resistance Doluol/ethanol mixture (23℃ x 24 hours)
Near H or higher The paints in Examples 2 to 4 were sufficiently applicable to work in a catalytic combustion baking furnace, as in Example 1.

As explained above, the characteristics of the paints for electric wires obtained by the present invention are that even when these paints adhere to the human body, they do not cause inflammation as seen with conventional cresol and N-methyl 2-pyrrolidone paints. It has no harmful odor and does not cause any harmful odor when handled.

Also, unlike in the case of water-soluble paints, there is the advantage that conventional catalytic combustion baking furnaces can be used as is.

In addition, in the case of water-soluble paints, the viscosity change is relatively large, whereas in the case of the paint according to the present invention, the change in viscosity is as good as in the case of ordinary organic solvent-based paints.

These properties are extremely effective as a pollution control measure and for industrial use.

Claims (1)

[Claims] 11.2.3.4-Butanetetracarboxylic acids and diamines are reacted in a single or mixed solvent of alcohol, polyhydric alcohol, polyhydric alcohol derivative, Kent, ether, and ester.Acid value residual rate 3~ A method for producing a paint for electric wires, which comprises forming an ammonium salt in a 30% polyimide precursor such that the amount of water in the total solvent is 20% by weight or less.