JPS6235410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a heat-resistant prepreg. More specifically, the present invention relates to a highly heat-resistant, strong, and highly flexible prepreg.

Conventionally, for electrical insulation, particularly interlayer insulation of electrical equipment coils or insulation of slot leads, etc., glass fiber base materials have been impregnated with polyester resin, urethane resin, aromatic bisphenol A type epoxy resin, etc. and dried. Prepreg is known.

Recently, as the use of these prepregs has progressed, particularly in the field of electrical insulation materials, as electrical equipment has become smaller and more sophisticated, the demand for products with even better heat resistance has increased.

In addition, much research has been done on the development of prepregs that can provide heat-resistant molded products, and silicone resins, polyamide-imide resins, and polyimide resins are already known as resins with excellent heat resistance. ing. but,
Products treated with silicone resin have negative effects such as low adhesive strength at high temperatures, poor solvent resistance, and deterioration products generated at high temperatures that promote abnormal wear of motor brushes. When treating other types of resin varnishes on resin-treated sheets, etc., they have drawbacks such as not being able to apply them uniformly and causing the varnish to rub. In addition, polyamide-imide resin or polyimide resin is manufactured by first obtaining polyamic acid as a precursor, and then dehydrating and ring-closing this by means such as heating. A possible method is to impregnate a base material with a precursor, polyamic acid, and then dry it. However, in order to obtain the polyamic acid,
The reaction solvent is limited to relatively expensive and special solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone, and there are various methods such as using the solvent in an anhydrous state as much as possible. There are many operational inconveniences that require careful attention, and when producing prepreg, impregnation operations are difficult due to the low concentration and high viscosity. Furthermore, when the polyamic acid prepreg is molded and heat cured, the polymer tends to deteriorate and yellowing occurs during the process, making it difficult to provide a molded product with sufficient strength. Furthermore, these prepregs have a resin structure that is rigid and inflexible, making operations such as taping very difficult. Furthermore, this polyamic acid generally has poor stability during storage and becomes unusable over time. It is also known to have drawbacks such as poor alkali resistance.

Therefore, the present inventors have conducted intensive studies on a method for manufacturing heat-resistant prepreg that has excellent workability, adhesiveness, flexibility, and electrical properties without having such drawbacks, and as a result, they have arrived at the present invention. .

[A] (a) General formula: An imide ring-containing dicarboxylic acid compound represented by (wherein R represents an aromatic or fatty acid diamine residue) and a polyfunctional epoxy resin are added to the carboxyl group 1 of the imide ring-containing dicarboxylic acid compound.
Epoxy group of polyfunctional epoxy resin per equivalent weight 1.6
Prepolymer 100 obtained by reacting an imide epoxy resin obtained by reacting at a ratio of ~50 equivalents and (b) diamine at a ratio of 0.5 to 1.5 equivalents of active hydrogen groups of the diamine per 1 equivalent of epoxy groups of the imide epoxy resin.
(parts by weight, the same applies hereinafter) and [B] A resin composition prepared by blending 1 to 20 parts of a thermoplastic polymer and dissolving it in an organic solvent, which is made of fibers such as glass, cellulose, aromatic polyamide, or aromatic polyester. Apply to one or both sides of a substrate such as woven fabric, non-woven fabric, paper or matte,
The prepreg is then dried to a semi-cured state to provide a prepreg with high heat resistance and excellent flexibility.

In the present invention, a prepolymer can be easily obtained by reacting an imide epoxy resin with excellent heat resistance with a diamine, and a thermoplastic polymer is further blended to form a linear chain in the cured fine particles of the imide epoxy resin. By filling with the polymer, it has the effect of reducing curing shrinkage and further imparting flexibility, and as an integrally cured product of these,
It provides excellent mechanical properties and thermal stability due to good flexibility and low shrinkage.

Generally, derivatives with imide rings are poorly soluble;
Conventionally, it was considered difficult to introduce imide rings into epoxy resins, but since the imidocarboxylic acid compound represented by the above general formula has a carboxyl group that reacts with epoxy groups, it can react with epoxy groups to form imide epoxy resins. can.

The imidocarboxylic acid compound represented by the above general formula used in the present invention is composed of 2 moles of trimellitic acid or trimellitic acid anhydride and the general formula H ₂ N
It can be easily obtained by heating and reacting with 1 mol of a primary diamine having -R-NH ₂ (wherein R is the same as above).

The primary diamines represented by the general formula H ₂ N—R—NH ₂ include 4,4′-diaminodiphenylpropane, 4.4′-diaminodiphenylmethane, benzidine, 3.3′-dichlorobenzidine, 4.4′-diamino Diphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether,
1.5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, m-xylylenediamine, p-xylylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, hexamethylenediamine, diaminopropyl, 1.4- Examples include diaminocyclohexane.

Examples of the polyfunctional epoxy resin used in the present invention include bisphenol A diglycidyl ether type Epicote 828, 834, 1001, or 1004 (manufactured by Ciel Chemical Co., Ltd.), and glycidyl ester type Araldite CY-182, 183. (manufactured by Ciba Corporation), but is not limited to these.

Further, the diamine as a curing agent used in the present invention is not particularly limited, and has the general formula H ₂ N-R-
Diamines represented by NH ₂ can be used.

The imide epoxy resin is prepared by mixing the epoxy group in a ratio of 1.6 to 50 equivalents to 1 equivalent of the carboxyl group of the imidocarboxylic acid compound at a temperature of 150 to 270°C without a catalyst or in the presence of a base catalyst. It can be obtained by reacting for 0.5 to 5 hours. Next, diamine was added to the imide epoxy resin in an amount equivalent to active hydrogen group per equivalent of epoxy group.
0.5 to 1.5 and react to form a prepolymer.

Here, the equivalent ratio of the epoxy compound was set to 1.6 to 50 equivalents per equivalent of the carboxyl group of the imidocarboxylic acid compound, because at less than 1.6 equivalents, the molecular weight of the product increases too much, and it is difficult to mix with the curing agent. This is because solubility decreases and workability deteriorates, and
This is because if the amount exceeds 50 equivalents, the resulting cured product will not have sufficient heat resistance. Although the reaction is preferably carried out without a solvent, an appropriate amount of a polar solvent such as N-methylpyrrolidone or N,N'-dimethylformamide may be used to further accelerate the reaction. Furthermore, we decided to blend diamine in an amount of 0.5 to 1.5 equivalents of active hydrogen groups per equivalent of epoxy group in the imide epoxy resin, because if the amount is less than 0.5 equivalents, sufficient crosslinking will not occur and various properties will deteriorate. This is because, if the amount exceeds 1.5 equivalents, the crosslinking density increases too much, and in particular, the mechanical properties deteriorate.

Further, thermoplastic polymers that can be used in the present invention include, for example, phenoxy resin, polysulfone, polyethersulfone, polycarbonate, polyester, polyesterimide, etc., and those having a molecular weight of about 10,000 to 100,000 are desirable, but molecular weights of 10,000 or less are acceptable. Flexibility etc. are insufficient, and if it exceeds 100,000, compatibility decreases and workability deteriorates. The blending ratio is 1 to 20 parts, preferably 1 to 10 parts, per 100 parts of the imide epoxy diamine prepolymer. If it is less than 1 part, the concentration in the cured resin will be too low and flexibility will not be sufficient. This is because if it exceeds 20 parts, it tends to flow at high temperatures and lacks mechanical stability.

The prepreg of the present invention is produced by reacting an imide epoxy resin and a diamine at 60°C to 180°C for 10 minutes to 2 hours to form a prepolymer, then adding a thermoplastic polymer and dissolving it in an organic solvent at an appropriate concentration. It is manufactured by applying it to base materials such as , cloth, and aromatic polyamide paper.

The treated substrate is brought to a semi-cured state (B stage) by air drying or in a drying oven, preferably dry to the touch at a relatively low temperature of 40 to 130°C, and dried at a temperature of 150°C or higher. The time should be kept within 2-3 minutes.

The prepreg of the present invention can be taped to an electrical conductor or sandwiched between thin foil electrical conductors, and then heated or pressurized after lamination to produce a coil having an insulating layer firmly bonded. In addition, the prepreg of the present invention can be laminated and pressurized and heated to form plates, tubes, and other shapes to produce molded products, which have excellent mechanical strength and electrical properties, and can be used for slots, wedges, liners, etc. Can be used for spacers and insulation tubes.

Next, the heat-resistant prepreg resin composition of the present invention will be explained with reference to Examples. The structural formula and abbreviation of the imidocarboxylic acid compound used in each example are shown below.

Example 1 27.3 g (0.1 equivalent) of an imidocarboxylic acid compound represented by the structural formula IC-1 and Epicote 828 (Ciel Corporation), which is a bisphenol A diglycidyl ether type epoxy compound with an epoxy equivalent of 190.
and 95 g (0.5 equivalent) of
The reaction was carried out at 200°C for 1 hour.

The product was a semisolid resin at room temperature with an epoxy equivalent weight of 300.

2500-2200cm by infrared absorption spectrum analysis
A decrease in acid-based absorption towards ^-1 was observed, imide ring absorption appeared near 1780 cm ^-1 and 1715 cm ^-1 , epoxy group absorption appeared near 910 cm ^-1 and 850 cm ^-1 , and imidoepoxy Production of resin was confirmed.

300g (1 equivalent) of the obtained imide epoxy resin
49.5 g (1.0 active hydrogen equivalent) of 4.4'-diaminodiphenylmethane was added to the solution in methyl cellosolve solvent.
A prepolymer was obtained by reacting at 100°C for 15 minutes. Furthermore, 30 g of phenoxy resin PKHH (Union Carbide Co., Ltd.) was added and completely dissolved to obtain a final resin composition solution of about 30 centipoise.

300mm of this resin composition solution (solid content approximately 30%)
Impregnate both sides of a square, 0.05 mm thick aromatic polyamide fiber paper (DuPont Nomx No. 410), squeeze between rolls, and dry at 120°C for 10 minutes to determine the amount of resin.
A prepreg sheet with 35% flexibility was obtained. The tensile load of this prepreg (thickness 0.080mm) is 6.5Kg/10mm width, cutting elongation is 15%, dielectric breakdown voltage in normal state is 2.0KV, and breakdown voltage after heating at 150℃ for 2 hours is 2.4 It was KV.

Also, stack 15 sheets of this prepreg sheet.
Dielectric breakdown voltage 55KV/mm when heated at 180℃55Kg/cm ² for 20 minutes, and 2
Insulation resistance after hours is 2×10 ⁷ MΩ or more,
Furthermore, the tensile strength was 13.0Kg/mm ² . In addition, the weight loss of the cured resin after 150 hours at 240℃ in air is 7.2
It was %.

Example 2 27.4 g (0.1 equivalent) of an imidocarboxylic acid compound represented by structural formula IC-2 and 133 of Epicote 828
g (0.7 equivalent) and reacted at 220°C for 1 hour.

The product is liquid at room temperature and has an epoxy equivalent of
It was 270.

As in Example 1, generation of imide epoxy resin was confirmed by infrared absorption spectrum.

270g (1 equivalent) of the obtained imide epoxy resin
, 93.8 g of 4,4′-diaminodiphenyl sulfone
(1.5 active hydrogen equivalents) in dioxane solvent.
0.4 g of BF ₃ -400 was added and reacted at 90°C for 2 hours to obtain a prepolymer. Add polysulfone P-1700 to this
(Union Carbide Co.) 5.0 g was added and completely dissolved to form a resin composition solution of about 30 centipoise.

Spread this resin composition solution into a 300mm square, 0.15mm thick
It was applied to one side of NOmex No. 411 and dried at 120°C for 20 minutes to obtain a prepreg sheet. The tensile load of this prepreg (thickness 0.20mm) is 7.0Kg/10mm
The width and cutting elongation were 4.5%, and the breakdown voltage under normal conditions and after 1 hour at 150°C was 2.0 KV and 2.8 KV, respectively.

Example 3 29.9 g (0.1 equivalent) of an imidocarboxylic acid compound represented by the structural formula IC-3 and 750 g (5.0 equivalent) of glycidyl ester type epoxy Araldite CY-183 (trade name of Ciba Corporation) were mixed, Using 0.3 g of potassium t-butoxide as a catalyst, the reaction was carried out at 180° C. for 2 hours to obtain a transparent and uniform resin.

The product was a fluid resin at room temperature and had an epoxy equivalent weight of 160. Generation of imide epoxy resin was confirmed by infrared absorption spectrum analysis. 32.4 g (1.2 active hydrogen equivalents) of metaphenylene diamine was added to 160 g (1 equivalent) of the obtained imide epoxy resin, and the mixture was reacted in an N,N-dimethylformamide solvent at 120° C. for 30 minutes to obtain a prepolymer. Furthermore, 10 g of phenoxy resin PKHH (Union Carbide) was added and completely dissolved to form a resin composition solution of about 20 centipoise.

Both sides of a 0.50 mm thick glass cloth were impregnated with this resin composition solution and dried at 130° C. for 10 minutes to obtain a highly flexible prepreg sheet with a resin content of about 35%. This sheet was made into a tape and wrapped in two layers in a half-overlap state around a rectangular copper wire.
The electrical conductor molded by heating under pressure for 10 minutes at Kg/ ^cm2 has a strongly bonded insulating layer and has a dielectric strength of
It showed 50KV/mm. In addition, this cured resin is
The weight loss after 150 hours at 240°C was 11.1%.

Example 4 232 g (1 equivalent) of an imidocarboxylic acid compound represented by structural formula IC-4 and 304 g of Epicote 828
(1.6 equivalents) were mixed, 0.05 g of benzyltrimethylammonium chloride was used as a catalyst, and 1.5
Allowed time to react.

The product was solid at room temperature and had an epoxy equivalent weight of 900.

Generation of imide epoxy resin was confirmed by infrared absorption spectrum analysis. To 900 g (1 equivalent) of this imide epoxy resin, 93.8 g (1.5 active hydrogen equivalent) of 4,4'-diaminodiphenylsulfone was added,
0.5 g of BF ₃ -400 was added and reacted in N-methylpyrrolidone at 110° C. for 15 minutes to obtain a prepolymer.
Further, 50 g of polysulfone resin 300P (ICI) was added and completely dissolved to obtain a resin composition solution of about 15 centipoise (25° C.).

Add a 300mm square, 0.18mm thick NOMEX to this solution.
Both sides of No. 411 were impregnated and heat treated at 130°C for 5 minutes to obtain a prepreg sheet. The dielectric breakdown voltage of 15 prepreg sheets stacked and heated and pressed at 170℃ for 15 minutes at 70Kg/ ^cm2 is 48.0KV/
mm, and showed a tensile strength of 9.8 Kg/mm ² .

In addition, this prepreg sheet was sandwiched between two aluminum metal pieces and heated under pressure (40Kg/cm ² ,
The adhesive strength between the metal pieces was 140Kg/cm ² (measured at 25℃) and 70Kg/cm ² (measured at 150℃), and the bonded metal pieces were held at 220℃ for 300 hours. Later measurements showed a value of 135Kg/cm ² .

Comparative example 1 358g of 4,4'-dimaleimidophenylmethane
(1 mol) and 123.3 g (0.9 mol) of p-aminobenzoic acid were placed in a flask, and after melting, they were reacted at 170°C for 15 minutes. Thereafter, it was dissolved in dimethylformamide, and 380 g (1 mol) of Epicote 828 was added to obtain a resin composition solution with a solid content of 30%. Spread this resin composition solution into a 300mm square with a thickness of 0.05mm.
Aromatic polyamide paper (manufactured by Dupont)
Nomex No. 410) was impregnated on both sides, squeezed between rolls, and dried at 120°C for 10 minutes to obtain a prepreg sheet with a resin content of 30%.

This prepreg sheet is not flexible and has a diameter of 20 mm.
When wrapped around a mandrel, cracks appeared.

Stack 15 of these prepreg sheets at 180℃ and 55℃.
The dielectric breakdown voltage after heat forming at Kg/cm ² for 20 minutes is as low as 30 KV/mm, and the adhesive strength when bonding aluminum pieces is 100 Kg/cm ² under normal conditions, and 60 Kg/cm ² after being held at 220°C for 300 hours. The decline was significant.

Claims (1)

[Claims] 1 [A] (a) General formula: (In the formula, R represents an aromatic or fatty acid diamine residue) The imide ring-containing dicarboxylic acid compound and the polyfunctional epoxy resin are added per equivalent of the carboxyl group of the imide ring-containing dicarboxylic acid compound, Base 1.6~
Prepolymer 100 obtained by reacting an imide epoxy resin obtained by reacting at a ratio of 50 equivalents and (b) diamine at a ratio of 0.5 to 1.5 equivalents of active hydrogen groups of the diamine per 1 equivalent of epoxy groups of the imide epoxy resin.
parts by weight and [B] A heat-resistant prepreg comprising a semi-cured resin composition blended with 1 to 20 parts by weight of a thermoplastic polymer and a base material supporting this resin composition.