JPH1135884A - Polyurehtane-based electrical insulating coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyurethane-based electrical insulating coating material capable of improving the heat resistance while making the most of characteristics that the direct soldering can be carried out without requiring the peeling of an insulating film, etc. SOLUTION: This electrical insulating coating material contains a masked isocyanate compound, containing an isocyanatobenzyl- phenylphthalimidecarboxylic acid, obtained by thermally reacting 2 mol trimellitic anhydride with 2-6.5 mol diphenylmethane diisocyanate in the presence of an organic solvent having >=135 deg.C boiling point and <=10 permittivity at 25 deg.C without any active hydrogen and formed only by the reaction of the anhydride group of the trimellitic anhydride and prepared by masking the isocyanate group of the isocyanatobenzyl-phenylphthalimidecarboxylic acid and the isocyanate groups of the diphenylmethane diisocyanate or its polyisocyanate derivative present in an excessive amount with a masking agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking isocyanate compound, an electrically insulating paint using the same, and an electrically insulated wire using the same, and more particularly, to a method of directly soldering without removing an insulating film. The present invention relates to a polyurethane-based electrically insulating paint which has improved heat resistance while making use of excellent properties such as the ability to use a polyurethane resin.

[0002]

2. Description of the Related Art Polyurethane-based electrically insulated wires have the property that they can be directly soldered without peeling off the insulating film, which is advantageous for wire terminal treatment and connection labor savings. Use is expanding. However, in recent years, electrical equipment has become lighter, thinner, shorter, smaller (type), higher performance, higher durability, lower cost, higher overall quality,
Due to demands such as severe use conditions, in addition to the above-mentioned direct solderability, with the rise in the use atmosphere temperature of electrical equipment,
The demand for high heat resistance is also increasing.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a technique capable of overcoming the drawbacks of the prior art.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a process for preparing trimellitic anhydride (2 mol) and diphenylmethane diisocyanate (2 mol).
To 6.5 moles in the presence of an organic solvent having a boiling point of 135 ° C. or higher and a dielectric constant at 25 ° C. and a dielectric constant of 10 or lower and having no active hydrogen is an anhydride of the trimellitic anhydride obtained by heating. Imide isocyanate by reaction of substance group only
And at least an isocyanate group of the imide isocyanate acid and an excess of the diphenylmethane diisocyanate or the isocyanate group of the polyisocyanate thereof. The present invention relates to a masked isocyanate compound characterized by being masked by a method described in (1). The present invention also relates to a polyurethane-based electrically insulating paint using the masking isocyanate compound. Further, the present invention relates to a polyurethane electric insulated wire using the polyurethane electric insulating paint.

In the present invention, trimellitic anhydride (hereinafter may be referred to as TMA) and diphenylmethane diisocyanate (hereinafter referred to as MDI) can be obtained based on the main reaction formula of the following chemical formula 1. And the boiling point is 13
The reaction is carried out by heating in the presence of an organic solvent having a dielectric constant at 5 ° C. or more and 25 ° C. and no active hydrogen having a dielectric constant of 10 or less.

[0006]

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In the above-mentioned reaction between isocyanate and carboxylic acid, an addition reaction with active hydrogen usually occurs, but the above-mentioned boiling point is 135 ° C. or more and the dielectric constant at 25 ° C. is 10 ° C. When a heat reaction is performed in the presence of the following organic solvent having no active hydrogen, a five-membered imide bond is formed by the reaction of only the anhydride group of trimellitic anhydride as described above, and the carboxylic acid of the TMA is reacted. The acid groups are unreacted and imide isocyanate acid can be obtained. In an organic solvent such as N-methylpyrrolidone and dimethylformamide which deviates from the above, such as a dielectric constant exceeding 10, a reaction between the carboxylic acid group of TMA and the isocyanate group occurs, and the above-mentioned imide isocyanate acid Can not get. In this case, an amide bond is formed, and -NH of the amide bond reacts with NCO of the MDI to cause gelation in the system and to generate an insoluble substance, so that a desired product cannot be obtained.

[0008] The boiling point of the organic solvent used in the present invention is a value at 760 mmHg (1 atm). 13
If the temperature is lower than 5 ° C., the above-mentioned desired reaction hardly occurs. When the dielectric constant exceeds 10 at a measurement temperature of 25 ° C.,
The above desired reaction is unlikely to occur. Specifically, the dielectric constant is a relative dielectric constant (ε ^, ), where ε ^, = Cp / Co, where Cp is the capacitance of the sample and Co is the capacitance D of empty (ε = 1). The use of an organic solvent having active hydrogen hardly causes the above-mentioned desired reaction. Examples of the organic solvent include, for example, the general formula H ₃ COOC (CH ₃ ) _n CO
A dibasic acid ester represented by OCH ₃ (where n is an integer of 1 to 10) is exemplified. Specific examples include:
DBE (trade name, manufactured by DuPont). Another example is methoxypropyl acetate (PMA).

[0009] In the present invention, TM in the presence of the above organic solvent
A2 mol and 2-6.5 mol of MDI are heated and reacted. MDI is used in excess, and a polyisocyanate form of the MDI is simultaneously synthesized. As described above, an imide isocyanate having a five-membered imide bond is obtained, and at the same time, a polyisocyanate of MDI can be obtained. That is, while obtaining imide isocyanate acid according to the above reaction formula, MD
Although it is costly to obtain the polyisocyanate form of I, the cost can be reduced by synthesizing simultaneously during the reaction. In order to obtain the polyurethane-based electric insulating paint having improved heat resistance, which can be directly soldered due to the above reaction, MDI is used in an amount of 2 to 2 mol of TMA.
6.5 mol.

[0010] In the present invention, the isocyanate group of the imide isocyanate acid and the diphenylmethane diisocyanate or polyisocyanate thereof present in excess.
The isocyanate group of the isomer is masked with a masking agent to obtain a masked isocyanate compound. The masking agent may be any as long as it holds active hydrogen, and is not particularly limited, but is preferably xylenolic acid, cresol
And phenol are used.

In the present invention, the masking isocyanate
Polyurethane-based electric insulating paint is constituted by using a compound. An example of the structure is composed of the masking isocyanate compound and a polyol component. Examples of the polyol component include a polyol having an active hydrogen, such as a polyester polyol, a polyurethane polyol, and an epoxy resin. Specific examples of polyester polyols include Nipporan 2008 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and Desmohen 600 (manufactured by Bayer).
Specific examples of polyurethane polymers include Desmohen D70
(Manufactured by Bayer AG). Specific examples of the epoxy resin include Epicoat 1007 (manufactured by Shell Chemical Co., Ltd.). One or more of the polyol components can be used. In addition to the masking isocyanate compound according to the present invention, general (poly) masking isocyanate compounds, for example, commercially available (poly) masking isocyanate, Compound [blocked polyisocyanate] can be used. Examples of the masking polyisocyanate include Coronate MS-50, C-2503,
AP-Stable (above, manufactured by Nippon Polyurethane Industry Co., Ltd.), CTS Table (manufactured by Bayer) and the like.
In the above-mentioned paint, a catalyst such as a metal octylate, a metal salt of naphthenate, or various amine compounds may be used as a catalyst, if necessary. As the amine-based compound, for example, commercially available Vulcatide (trade name, manufactured by Bayer AG) or the like can be used. Also, polyvinyl formal,
Thermosetting resin such as polyamide, phenoxy, polyester, polyurethane, polyurethane polyol, polyether, polysulfone, and polyetherimide; thermosetting of phenol, melamine, polyester, polyesterimide, polyamideimide, polyesteramideimide, polyimide, and polyhydantoin A hydrophilic resin can be added. Further, additives such as dyes, pigments, lubricants, antioxidants, and inorganic substances can be added.
Organic solvents such as phenols such as xylenoleic acid, cresol and phenol, and glycol ethers can be used for the electrically insulating coating in the present invention. NMP
A solvent such as (N-methyl-2-pyrrolidone), DMF (N, N-dimethylformamide), and DMAc (N, N-dimethylacetamide) may be used. Further, xylene, solvent naphtha, or the like can be used as a diluent. In addition, cellosolves, glycol esters, γ-butyl lactone, anone, DMSO, alcohols, methyl lactate, which are used as solvents for insulating coatings,
Ethyl lactate, furfural and the like can also be used.

When the above paint according to the present invention is applied to a conductor and baked, a urethane bond and an amide bond are formed, and the obtained coating film can be directly soldered and heat resistance can be improved. The heat resistance can be improved without deteriorating the excellent characteristics of the polyurethane insulated wire.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[0014]

Next, the present invention will be described based on examples and comparative examples. Example 1 Synthesis of Masking Isocyanate Compound A mantle heater, a thermometer, a stirrer, a condenser, and nitrogen gas (1 liter / m) were placed in a 3 liter 4-neck round bottom flask.
in), TMA 682 g, MD
I, 349 g, DBE (boiling point: 196 to 225 ° C./76
442 g) (0 mmHg, dielectric constant: 8.00 / 25 ° C.), and reacted at 130 ° C. for 5 hours. Next, DBE 4
44 g was added to lower the temperature of the system to 100 ° C. or lower, 700 g of xylenoleic acid (containing 1 g of N-methylmorpholine) was added, the masking was stabilized at 130 ° C. for 2 hours, and 254 g of cresylic acid was added. As a result, a 50% stabilized masking isocyanate compound solution (hereinafter referred to as A-1) was obtained.

Example 2 Synthesis of Masking Isocyanate Compound 295 g of TMA, 673 g of MDI, and 416 of DBE
g, then adding 559 g of DBE, stabilizing the masking by adding 715 g of xylenolic acid, and then stabilizing masking isocyanate in the same manner as in Example 1 except that 249 g of diluted cresylic acid was added. A compound solution (hereinafter, referred to as A-2) was obtained.

Example 3 Synthesis of masking isocyanate compound 274 g of TMA, 714 g of MDI, DBE 424
g, followed by 507 g of DBE and 776 of xylenoleic acid
g, a diluted masked isocyanate compound solution (hereinafter, referred to as A-3) was obtained in the same manner as in Example 1 except that the amount of diluted cresolic acid was 263 g.

Examples 4 to 12 (I) Preparation of Insulating Paint An insulating paint was prepared according to the formulation shown in Table 1 using the stabilized masking isocyanate compound solution obtained above.
The materials in the table are as follows. Polyol 1: 60% solution of Desmohen 600 (manufactured by Bayer) diluted with cresylic acid / xylene = 7/3 Polyol 2: Polyurethane polyol production example described in JP-B-60-50389 Cresol 40% solution of A Polyol 3: Cresolic acid / xylene = 8 / of polyesterimide production example 3 described in JP-B-64-4527.
43% solution diluted in 2 Catalyst: Vuelcat 576 manufactured by Bayer AG (II) Preparation of insulated wire The insulating paint obtained above was applied to a conductor made of a round copper wire having a diameter of 0.35 mm in a horizontally elongated electric heating furnace (furnace length). 3m), inlet temperature 430 ° C, outlet temperature 450 ° C, felt 7 times, linear velocity 3
Coating and baking under conditions of 5 m / min.
Insulated wires were made to be 7 to 18 microns. The characteristics of the electric wire were measured in accordance with the test method of JIS C-3003. Table 2 shows the results.
In addition, for comparison, TP which is a usual polyurethane-based paint is used.
U5135 (trade name, manufactured by Toku Paint Co., Ltd.) “Comparative Example 1” and TSF23 which is a polyesterimide urethane heat-resistant paint
Insulated wires were similarly prepared using 0-3 (trade name, manufactured by Totoku Paint Co., Ltd.) “Comparative Example 2”, and the characteristics evaluation results are shown in Table 1.

[0018]

[Table 1]

[0019]

[Table 2]

From the results shown in Table 2, the insulating paint according to the present invention is significantly superior in heat resistance (residual breakdown voltage) and softening point temperature to the insulating paint according to the comparative example. You can see that. Further, it can be seen that the soldering characteristics are also excellent.

[0025]

As described above, according to the present invention, it is possible to provide a polyurethane-based electric insulating paint which can be directly soldered without having to peel off the insulating film and has excellent heat resistance.

Claims (3)

[Claims] 1. A mixture of 2 mol of trimellitic anhydride and 2 to 6.5 mol of diphenylmethane diisocyanate having a boiling point of 1 mol.
An imido isocyanate obtained by a reaction of only an anhydride group of the trimellitic anhydride obtained by performing a heating reaction in the presence of an organic solvent having no active hydrogen having a dielectric constant of 10 or less at 35 ° C. or more at 25 ° C. At least the isocyanate group of the imide isocyanate acid and the excess isocyanate group of the diphenylmethane diisocyanate or polyisocyanate thereof. A masking isocyanate compound characterized by being masked with an agent. 2. A polyurethane-based electrically insulating paint comprising the masking isocyanate compound according to claim 1. 3. An electrically insulated wire, wherein the electrically insulative paint according to claim 2 is applied and baked on a conductor.