JPH107984A - Insulation coating material - Google Patents

Abstract

(57) Abstract: An insulating coating material using a polycarbodiimide copolymer in which 5% or more of isocyanate residues are 2,4'-diphenylmethane diisocyanate residues. The polycarbodiimide copolymer, which is an insulating coating material according to the method of the present invention, is a polycarbodiimide that exhibits unprecedented flexibility while maintaining the high heat resistance of a conventional cured polycarbodiimide. It can be applied to insulating coatings on electric wires and electric boards, etc., which were not applicable to conventional cured products of polycarbodiimide copolymers because of their brittleness, while requiring heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant insulating covering material mainly composed of a polycarbodiimide copolymer having high heat resistance, chemical resistance and electrical insulation.

[0002]

2. Description of the Related Art In recent years, as electronic circuits have become smaller and lighter, wires and cables have become thinner and lighter, and boards have become thinner.
Weight reduction is being promoted. Therefore, an insulating coating made of a thermosetting resin capable of reducing the thickness of the coating is used as a very effective means. Conventionally, thermosetting resins used as heat-resistant insulating coating materials include epoxy-based, silicone-based, polyurethane-based, polyamideimide-based, polyimide-based, and polyesterimide-based resins. However, since the imide-based coating material having high heat resistance is expensive, a material that is less expensive and has high heat resistance is required.

[0003] Polycarbodiimide using only inexpensive isocyanate as a raw material is a thermosetting heat-resistant material that can be provided at low cost, but polycarbodiimide after thermosetting has a high hardness, so that wires and metals coated with polycarbodiimide are hardened. When the plate is wound or bent, there is a disadvantage that the coating is broken, and the polycarbodiimide alone has not been used in the field of heat-resistant insulating coating.

[0004]

If a cured product of polycarbodiimide having high heat resistance, electrical insulation and chemical resistance can be imparted with sufficient flexibility, it is useful as an inexpensive heat-resistant insulating coating material. It is considered to be.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, 5% or more of the diisocyanate residues in the polycarbodiimide molecule have been removed.
The inventors have found that a polycarbodiimide having sufficient flexibility can be obtained by using a 2,4′-diphenylmethane diisocyanate residue, and reached the present invention. That is, the present invention provides (1) a heat-resistant insulating coating material mainly composed of a polycarbodiimide copolymer having a structure represented by the following general formula (1):

[0006]

R'-N = C = N- (RN = C = N-) n-R '(1) (where n represents an integer of 4≤n≤100, and R'
Represents a monoisocyanate residue. R represents an organic diisocyanate residue, and the organic diisocyanate residue contains a structural unit represented by the following formula (2) [Formula 4] in an amount of 5% or more of all the structural units of the organic diisocyanate residue. )

[0007]

Embedded image (2) The organic diisocyanate residue is each of 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, and norbornane diisocyanate 1 selected from the group of isocyanate residues
(1) The heat-resistant insulating coating material according to (1), wherein the object to be coated is a metal. Materials.

That is, in the present invention, the polycarbodiimide copolymer contains at least 5% of 2,4'-diphenylmethane diisocyanate residues among the diisocyanate residues, so that heat resistance is not sacrificed. A cured product having flexibility can be obtained, and a coating excellent in heat resistance and flexibility can be obtained by coating and curing an electric wire or a metal plate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail. The polycarbodiimide copolymer polymerized in the present invention is represented by the following general formula (1)

[0010]

R'-N = C = N- (RN = C = N-) n-R '(1) R in the general formula (1) represents an organic diisocyanate residue (here, the organic diisocyanate residue refers to a remaining portion obtained by removing an isocyanate group (NCO) from an organic diisocyanate molecule), for example, 2 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 2,4'-MDI), 4,4'-diphenylmethane diisocyanate (hereinafter 4,4'-MDI)
), 2,4-tolylene diisocyanate (hereinafter abbreviated as 2,4-TDI), 2,6-tolylene diisocyanate (hereinafter abbreviated as 2,6-TDI), hexamethylene diisocyanate, norbornane diisocyanate, Residues such as xylylene diisocyanate, isophorone diisocyanate and naphthylene diisocyanate can be mentioned, and 2,4′-MDI, 4,4′-MDI,
2,4-TDI, 2,6-TDI, hexamethylene diisocyanate, and norbornane diisocyanate are easily available industrially and are preferable. In addition, these diisocyanate residues may be present alone or in a mixture of two or more in the polycarbodiimide copolymer,
Among the diisocyanate residues contained in the polycarbodiimide copolymer, the structural unit of 2,4′-MDI residue (the following formula (2) [Formula 6]) is contained in an amount of 5% or more of all the structural units of the diisocyanate residue. Have to do it.

[0011]

Embedded image Further, R ′ in the general formula (1) is an organic monoisocyanate residue (here, the organic monoisocyanate residue means a remaining portion obtained by removing an isocyanate group (NCO) from an organic monoisocyanate molecule. And isocyanate residues such as phenyl isocyanate, 1-naphthyl isocyanate, alkyl (1 to 18 carbon atoms) isocyanate, and methoxyphenyl isocyanate. Further, n in the general formula (1) represents an integer of 4 or more and 100 or less.

The polycarbodiimide copolymer of the present invention is obtained by reacting an organic diisocyanate in the presence of a catalyst for carbodiimidization. Of the organic diisocyanate used, 5 mol% or more, preferably 10 mol% or more of 2,2 is used. It is manufactured by making it 4'-MDI. 2,4'-
If the amount of the MDI is less than 5 mol%, it is not preferable because when the polymerized polycarbodiimide copolymer is cured, only a cured product having insufficient flexibility can be obtained.

The organic diisocyanate used to obtain the polycarbodiimide copolymer of the present invention is 2,4 '
-MDI, 4,4'-MDI, 2,2'-diphenylmethane diisocyanate (hereinafter, 2,2'-MDI),
2,4-TDI, 2,6-TDI, isophorone diisocyanate, naphthylene diisocyanate, paraphenylene diisocyanate, metatetramethyl xylylene diisocyanate, paratetramethyl xylylene diisocyanate, norbornane diisocyanate, hexamethylene diisocyanate, and the like. , 4'-MD
I, 4,4'-MDI, 2,4-TDI, 2,6-TD
I, hexamethylene diisocyanate and norbornane diisocyanate are preferred because they are industrially available. These diisocyanates may be used alone or as a mixture of two or more, but 2,4′-MDI is 5 mol%.
More preferably, it must be contained in an amount of 10 mol% or more.

In the present invention, various carbodiimidization catalysts can be used as the catalyst used to obtain the polycarbodiimide copolymer, but 1-phenyl-2-phospholene-
1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, 1-phenyl-2-phospholene-
1-sulfide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-1-
Phospha-3-cyclopentene-1-oxide, 2,5
-Dihydro-3-methyl-1-phenylphosphol-1
-Oxides, isomers corresponding thereto, and 3-phospholenes are good, and can be used in an amount of 0.001 to 1% by weight based on the total amount of the isocyanate component used. 0.
If it is less than 001%, the polymerization takes too much time to be practical, and if it exceeds 1% by weight, the reaction is too fast to cause gelation, and those that do not gel are only those whose storage stability of the solution is significantly reduced. It tends not to be obtained.

The stability of the solution can be improved without lowering the heat resistance by controlling the molecular weight by sealing the terminal of the polycarbodiimide copolymer used in the present invention with a monoisocyanate. Examples of the monoisocyanate used for this purpose include phenyl isocyanate, alkyl (1 to 10 carbon) isocyanate, naphthyl isocyanate and the like. This monoisocyanate can be used in the range of 2 to 25 mol per 100 mol of the diisocyanate component used. If less than 2 moles of the monoisocyanate component is used per 100 moles of the diisocyanate component (when n> 100 in the formula (1)), the molecular weight of the synthesized polycarbodiimide becomes too large, and the viscosity of the solution increases and This leads to a significant decrease in storage stability. When the monoisocyanate component is used in an amount of more than 25 moles per 100 moles of the diisocyanate component (when n <4 in the formula (1)), the number of carbodiimide bonds contained in the synthesized polycarbodiimide molecule is small, and There is a tendency that carbodiimide cannot exhibit the inherently high heat resistance.

The polycarbodiimide copolymer of the present invention can be obtained by carrying out a carbodiimidation reaction in an aprotic organic solvent to obtain a polycarbodiimide copolymer solution. Examples of aprotic organic solvents used for this purpose include toluene, xylene, benzene, perchene, cyclohexanone, trimethylbenzene, tetramethylbenzene, alkyl (2 to 4 carbon atoms) toluene, alkyl (3 to 36 carbon atoms) benzene, , Diethylbenzene, naphthalene, tetrahydrofuran, dioxane and the like.
More than one kind may be mixed and used, and a third component not involved in the reaction may be mixed. The amount of these solvents used is such that the concentration of the polycarbodiimide copolymer in the solution is 1%.
It is used so as to be 90% by weight. 90% by weight
If it exceeds, the viscosity will be high and the storage stability of the solution will be poor. On the other hand, when the concentration is less than 1% by weight, most of the solution becomes a solvent, and a large amount of the solvent must be evaporated during curing, which is not practical.

If the polycarbodiimide copolymer obtained by the method of the present invention reacts with carbodiimide to cause gelation immediately and cannot be coated on electric wires or metal plates, dicyanate is optionally used. Compounds, substances which accelerate the curing of polycarbodiimides such as diamine compounds and diphenol compounds, and plasticizers such as phosphoric acid esters may be mixed and used.

The metal used as a coating target in the method of the present invention includes copper, iron, nickel, stainless steel, aluminum, silver, gold and the like, and these metals may be used alone or in an alloy of two or more. Absent. Further, the shape of these metals may be a thread shape, a plate shape, or a formed shape.

The polycarbodiimide copolymer of the present invention comprises
For example, it is manufactured by the following method and coated on a metal. 40% 2,4'-MDI in xylene and 4,
20 mol parts of a 4% -MDI 60% mixture and 2 mol parts of phenyl isocyanate are mixed, and a carbodiimidization catalyst is added to the mixture, and the mixture is stirred at 60 to 140 ° C. for 1 hour.
It is manufactured by performing a carbodiimidation reaction for up to 24 hours. After coating the polycarbodiimide copolymer on the metal surface or immersing the metal in the carbodiimide copolymer solution and taking it out, the product is placed in an oven at 250 to 400 ° C. for 5 minutes.
By curing for seconds to 30 minutes, a coated metal can be obtained.

[0020]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In addition, the copolymers obtained in Examples and Comparative Examples and the copolymer solutions (hereinafter referred to as varnishes) were analyzed and physical properties were measured by the following methods.

<< Solid content concentration >>: Approximately 1 g of a varnish is spread on an aluminum cup having a diameter of 5 cm, precisely weighed, heated under nitrogen at 120 ° C. for 2 hours, further heated to 230 ° C. for 1 hour, and dried in a desiccator. Transfer to room temperature and weigh accurately. Thereafter, the concentration of the solid content is calculated by the following equation. Solid content concentration (% by weight) = (1− (initial weight−weight after drying) / initial weight) × 100 << 5% weight loss temperature >>: Differential heat / thermogravimetric analysis of sample after measuring solid content concentration In the air using the device, the temperature was raised to 16 ° C /
The 5% weight loss temperature of the polymer was measured in minutes.

<< Evaluation of Flexibility as Electric Wire Coating Agent >>: A step of attaching a varnish to a copper wire having a diameter of 0.5 mm, wiping with a felt, and curing at 300 ° C. for 15 minutes was repeated 7 times. 5,2.0,1.5,1.0,0.5
mm stainless steel rods (hereinafter 5d, 4d, 3d,
2d, 1d), and wrap it around 360 °
The diameter of the copper wire coating when wound was observed.

<< Evaluation of Flexibility as Metal Plate Coating Agent >>: 5
A varnish was applied to one side of a copper plate and an aluminum plate (hereinafter referred to as an aluminum plate) of 0 mm (length) × 50 mm (width) × 0.5 mm (thickness) so as to have a solid content of carbodiimide of 0.1 g at 120 ° C. After allowing the solvent to evaporate in the oven for 1 hour, it is transferred to an oven at 300 ° C. and cured for 15 minutes. The cured product was taken out, and after cooling, the metal plate was folded in two so that the coated surface was on the outside, and it was observed how far the cured product was cracked when bent. (Maximum bending angle is 180 °) << Inspection of residual isocyanate >>: A part of the solution during polymerization is sampled, sandwiched between rock salt plates, and an infrared absorption spectrum measuring device (I
The reaction was continued using R) until no infrared absorption of the isocyanate was observed.

Example 1 1000 m equipped with a stirrer, thermometer and cooling condenser
38% 2,4'-MDI in a separable flask;
62% 4,4'-MDI mixture (trade name; o-MD
I, 239.8 g of Mitsui Toatsu Chemicals, Inc., 15.2 g of phenyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 490.0 g of xylene, 2,5-dihydro-3-methyl-
0.185 g of 1-phenylphosphol-1-oxide (manufactured by MERCK) is added, and the mixture is stirred and heated while flowing nitrogen gas into the gas phase. When the reaction was continued for 8 hours while maintaining the internal temperature at 105 ° C., a pale yellow transparent polycarbodiimide copolymer solution was obtained.

A part of this solution was taken out, and the solid concentration was measured to be 30.1%. The 5% decomposition temperature was 533 ° C. The flexibility of the copper wire was good without cracking even when wound by 1d. The flexibility of the copper plate was good without cracking even when bent to 180 °. The flexibility of the aluminum plate was good without cracking even when bent to 180 °.

Example 2 120.0 g of o-MDI, 4,4'-MDI 11
Example 1 except that a mixture of 9.8 g (trade name; Cosmonate MDI-PH, manufactured by Mitsui Toatsu Chemicals, Inc.) was used.
In the same manner as described above, a slightly yellow transparent polycarbodiimide copolymer solution was obtained. The analysis and physical properties are shown in Table 1.

EXAMPLE 3 Distillation of o-MDI yielded 82% 2,4'-MDI,
A mixture of 4,4'-MDI 18% was obtained. A slightly yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1 except that 239.8 g of this mixture was used. The analysis and physical properties are shown in Table 1.

Example 4 144.3 g of o-MDI, 2,4-TDI 100.
A slightly yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1 except that 5 g and 19.7 g of phenyl isocyanate were used. The analysis and physical properties are shown in Table 1.

Example 5 36.2 g of o-MDI, 211.5 g of MDI-PH
And a slightly yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1, except that 13.12 g of phenyl isocyanate was used. The analysis and physical properties are shown in Table 1.

Example 6 A slightly yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1 except that xylene of Example 1 was replaced with 490.0 g of toluene. Table of analysis and physical properties
It is shown in FIG.

Example 7 399.6 g of o-MDI, phenyl isocyanate 2
Using 5.4 g and 350.0 g of xylene, the reaction time was 1
A light yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1 except that the time was changed to 0 hour. The analysis and physical properties are shown in Table 1.

Example 8 273.5 g of o-MDI, 2,4-TDI and 2,6-TDI
Mixtures of TDI of 80% and 20% respectively (trade name: Cosmonate T-80, manufactured by Mitsui Toatsu Chemicals, Inc.) 19
0.5 g, 17.0 g of 1-naphthyl isocyanate,
The same procedure as in Example 1 was carried out except that the reaction was carried out using 0.21 g of 2,5-dihydro-3-methyl-1-phenylphosphol-1-oxide and 600.0 g of toluene for 12 hours. A carbodiimide copolymer solution was obtained.
The analysis and physical properties are shown in Table 1.

Comparative Example 1 25-7.0 g of T-80, phenyl isocyanate 2
A slightly yellow transparent polycarbodiimide copolymer solution was obtained in the same manner as in Example 1 except that polymerization was performed using 2.0 g. The analysis and physical properties are shown in Table 1.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that 239.8 g of MDI-PH was used. As a result, a white fine powder was precipitated.
Flexibility cannot be evaluated.
It is shown in FIG.

Comparative Example 3 MDI-PH 228.8 g o-MDI 11.0 g
Polymerization was carried out in the same manner as in Example 1 except that was used as a mixture. As a result, a small amount of white precipitate was observed and a viscous liquid was obtained. The analysis and physical properties are shown in Table 1.

Comparative Example 4 1000 m equipped with a stirrer, thermometer and cooling condenser
190.4 g of T-80 in a separable flask;
Polyetherdiol (trade name: Diol1000, manufactured by Mitsui Toatsu Chemicals, Inc., weight average molecular weight: 1000), and urethanization of polyetherdiol and TDI for 1 hour at 80 ° C. for 1 hour with stirring and 490.0 g of xylene. After the reaction, 15.2 g of phenyl isocyanate, 2,
5-dihydro-3-methyl-1-phenylphosphol-
An additional charge of 0.185 g of 1-oxide was added and 105
A carbodiimidation reaction was carried out at 8 ° C. for 8 hours to obtain a pale yellow transparent partially urethane-modified polycarbodiimide copolymer solution. The analysis and physical properties are shown in Table 1.

[0037]

[Table 1]

[0038]

According to the polycarbodiimide copolymer of the present invention, a cured product having good flexibility can be obtained without lowering the heat resistance of the conventionally known polycarbodiimide. It is useful when used as a heat-resistant insulating coating material by coating it on electric wires or metal plates, and has extremely high industrial utility value.

Claims (3)

[Claims] 1. A heat-resistant insulating coating material mainly composed of a polycarbodiimide copolymer having a structure represented by the following general formula (1). R'-N = C = N- (R-N = C = N-) n-R '(1) (where n represents an integer of 4≤n≤100;
Represents a monoisocyanate residue. R represents an organic diisocyanate residue, and the organic diisocyanate residue contains a structural unit represented by the following formula (2) [Formula 2] in an amount of 5% or more of all the structural units of the organic diisocyanate residue. ) 2. The method according to claim 1, wherein the organic diisocyanate residue is 2,4′-
One or more selected from the group of the respective isocyanate residues of diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, and norbornane diisocyanate 2. The heat-resistant insulating covering material according to claim 1, wherein: 3. The heat-resistant insulating coating material according to claim 1, wherein the object to be coated is a metal.