JPH04314754A - Composition for producing flexible heat-resistant insulation sheet or film and flexible heat-resistant insulation sheet or film - Google Patents

Abstract

PURPOSE:To obtain a heat-resistant insulation sheet or film which has flexibility and can be inexpensively provided as a replacement for a heat-resistant insulation sheet comprising mate-oriented aramid polymer and a composition for producing the same. CONSTITUTION:A flexible heat-resistant insulation sheet or film which comprises an epoxy resin having at least two epoxy groups in the molecule, a heat- resistant thermoplastic resin selected from the group consisting of polyparabanic acid, polyamidoimide and polyimide, and a curing agent having a flexibilizing effect as essential components, and a composition for producing the same.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a composition for producing a sheet or film that is flexible and has excellent heat resistance and insulation properties, and a flexible sheet formed by molding the composition into a sheet. Regarding the heat-resistant insulating sheet or film, this sheet or film is useful as an insulating sheet or film (hereinafter referred to as sheet) used for dry transformers, motors, generators, etc.

0002

BACKGROUND OF THE INVENTION The flexible heat-resistant insulating sheet used for the above-mentioned insulation purposes is currently available as a product manufactured by DuPont and sold under the trade name "Nomex." This sheet is a meta-aromatic aramid polymer with the structural formula below.

0003

[Chemical formula 1]

A heat-resistant insulating sheet, which is made from short fibers mainly composed of It is widely used as a material.

However, this insulating sheet has the disadvantage of being very expensive economically, and also has the disadvantage that its electrical insulation properties deteriorate after a relatively short period of use due to its hygroscopic properties. This sheet is made from short fibers and has numerous interfiber voids, so it cannot be said that the electrical insulation properties of the material itself are fully utilized, and the dielectric breakdown strength is also lacking.

On the other hand, epoxy resins have excellent mechanical and electrical properties and are cheaper than the aramid polymers mentioned above, so they can be used as various molding materials and fiber-reinforced materials for electrical and electronic parts. It is widely used as a binder for composite materials such as resins. However, epoxy resin generally has poor flexibility, making it unsuitable as a sheet molding material, and the aforementioned "Nomex"
Because its heat resistance and insulation properties are insufficient compared to that of , it cannot be put to practical use as a sheet material that requires a high level of heat resistance and insulation, such as in transformers and generators.

[0007]

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to use an inexpensive epoxy resin as a main component and use it as an insulating sheet material for generators, etc. An object of the present invention is to provide a composition that has heat resistance and insulation properties that can be put into practical use sufficiently, and can provide a sheet with good flexibility, and a flexible heat-resistant insulating sheet using the composition. It is something to do.

[0008]

[Means for Solving the Problems] The structure of the sheet manufacturing composition according to the present invention that can solve the above problems is (
a) 100 parts by weight of an epoxy resin having at least two epoxy groups in the molecule, (b) polyparabanic acid,
The gist is that it contains 1 to 33 parts by weight of at least one heat-resistant thermoplastic resin selected from the group consisting of polyamideimide and polyimide, and (c) a curing agent that has a flexibility imparting effect, When this composition is molded into a sheet, a heat-resistant insulating sheet with excellent flexibility can be obtained.

[0009]

[Operation] The constituent materials of the sheet manufacturing composition according to the present invention will be explained in detail below. First, the epoxy resin is the main component in the composition of the present invention, and its type is not particularly limited. It must have two or more epoxy groups.

Specific examples of such epoxy resins include:
Diglycidyl ether of bisphenol A and its polymers such as epibis type epoxy resin, bisphenol F type epoxy resin, resorcinol type epoxy resin, tetrahydroxyphenylethane type epoxy resin, cresol type epoxy resin, novolak type epoxy resin, polyolefin type Examples include epoxy resins, alicyclic epoxy resins, and halides thereof. These epoxy resins may be used alone or in combination of two or more.

Next, the curing agent having the effect of imparting flexibility is one that acts as a curing agent for the above-mentioned epoxy resin and also imparts flexibility to the cured product, and as a curing agent, diamines having a relatively large molecular weight are used. Preferred examples include dicarboxylic acid or its anhydride, polyamide, and the like. Specific examples of such curing agents include 3,9-bis(
Polyether diamines such as diethylene glycol bispropylamine, silicone main chain Preferred examples include diamines containing dodecenyl succinic anhydride, and dehydrated polycondensates of dicarboxylic acids such as polyadipic anhydride, polyazelaic anhydride, and polysebacic anhydride. It is also effective to use these curing agents together with an appropriate amount of curing accelerator (benzyldimethylamine, triethylamine, dimethylaminomethylphenol, trisdimethylaminomethylphenol, etc.), if necessary.

[0012] Heat-resistant thermoplastic resins are used to increase the mechanical strength of cured epoxy resins without reducing their heat resistance or insulation properties, and include polyparabanic acid, polyamideimide, and polyimide. One or more selected from the group consisting of: Among these, polyparabanic acid is particularly preferred in order to obtain a high level of heat resistance and insulation, and the following polyparabanic acid is one of the most preferred heat-resistant thermoplastic resins.
Awarded as one. Although these resins are thermoplastic, they have excellent strength and heat resistance, and by blending an appropriate amount with an epoxy resin, the epoxy resin added with a curing agent that has a flexibility imparting effect can be used. It compensates for the lack of strength of the resin and also improves its electrical insulation properties, making it more suitable as a heat-resistant insulation sheet material.

[0013]

[Case 2]

The above-mentioned heat-resistant thermoplastic resin must be used in an amount of 1 to 33 parts by weight per 100 parts by weight of the epoxy resin, and if the amount of the thermoplastic resin is insufficient, it may be necessary to A composition with comparable mechanical strength cannot be obtained. Moreover, if the amount of the thermoplastic resin blended is too large, the flexibility will deteriorate and the suitability as a flexible sheet material will be lost. A more preferable blending amount of the thermoplastic resin in order to exhibit mechanical strength and flexibility (flexibility) in a well-balanced manner is in the range of 5 to 25 parts by weight based on 100 parts by weight of the epoxy resin.

Further, the amount of the curing agent that has the effect of imparting flexibility is not particularly limited, but if the amount added is too small, the epoxy resin will be insufficiently cured and satisfactory strength will not be obtained.
On the contrary, too much plasticizing action tends to result in insufficient strength, so it is preferably 30 to 130% by weight, more preferably 60 to 110% by weight based on the epoxy resin.
It is desirable to use it within a range of % by weight. Although the curing accelerator is not essential, it is effective to use it in an appropriate amount depending on the type and use of the curing agent, and the preferable amount is 0.1 to 3% by weight based on the epoxy resin. Preferably it is in the range of 0.2 to 2% by weight.

The essential components of the present invention are as described above, but depending on the application and required characteristics, other components such as inorganic fillers, organic fillers, It is also possible to blend appropriate amounts of inorganic fiber reinforcing materials, organic fiber reinforcing materials, antioxidants, colorants, plasticizers, etc. as desired.

[0017] The method of forming the composition of the present invention into a sheet or film is not particularly limited, and various known methods can be employed, but the most common method is to form each compounded raw material into a solvent such as dimethylformamide. This method involves dissolving and mixing uniformly, heating to remove as much of the solvent as possible, placing it in a mold, heating in a vacuum to completely remove the solvent, and proceeding with the curing reaction by molding or compression molding. be. In addition, when employing such a molding method, it is necessary to apply a mold release agent to the mold in advance. In addition, there is a method in which a resin solution is applied onto a substrate to an appropriate thickness and heated to volatilize and remove the solvent, or after the solvent is volatilized and removed, the curing reaction proceeds. In this method, it is also possible to form a cured film made of the above composition on the surface of, for example, aluminum foil, and then dissolve and remove the aluminum foil using dilute hydrochloric acid or the like to obtain a film-like product. In addition, the sheet or film obtained in this way can be made into a laminated structure, and depending on the use, a sheet or film with a laminated structure in which a film of the composition according to the present invention is formed on a substrate sheet or film can be used. It is also possible to put it into practical use as

[0018]

[Example] Bisphenol A type epoxy resin with an epoxy equivalent of 190 as an epoxy resin (manufactured by Yuka Ciel Co., Ltd., trade name "Epicote 828"); polyparabanic acid (manufactured by Tonen Petrochemical Co., Ltd. with a polyparabanic acid concentration of 30) as a heat-resistant thermoplastic resin % DMF solution), polyamideimide (manufactured by Amoco Japan Co., Ltd., trade name "Torlon 4203L":
Polyamideimide (N-methylpyrrolidone solution with a concentration of 10%) or polyimide (manufactured by Mitsui Toatsu Chemical Co., Ltd., product name "L")
ARC-TPI": N-methylpyrrolidone solution with polyimide concentration of 10%); polysebacic anhydride (manufactured by ACI Japan) as a curing agent and dimethylaminomethylphenol as a curing accelerator were used in the proportions shown in Table 1. , conducted the following experiment.

[0019]

[Table 1]

That is, the epoxy resin was mixed with 1.5 times the amount of dimethylformamide (DMF) (Examples 1 to 3 and Comparative Examples 1 and 2) or N-methylpyrrolidone (NMP) (Examples 4 to 9 and Comparative Example 3, 4), a curing agent and a curing accelerator are added thereto to make a uniform solution, and a DMF solution of the thermoplastic resin is added thereto and mixed uniformly. This mixed solution was applied to an Al plate (30 cm x 40 cm) with an applicator to a dry thickness of 100 μm, heated on a hot plate to volatilize the solvent (DMF), and then heated at 140 °C for 1 hour. Another 150 hours x 2
Heat and cure for 0 hours.

After curing is completed, the Al plate is dissolved and removed with dilute hydrochloric acid, washed with water and dried to form a flexible sheet with a thickness of 100 μm.
A thick cured sheet was obtained. Each sheet obtained was subjected to a tensile test (JISK 7127) and an MIT bending test (JISK 7127).
P8115) and Electrical Dielectric Breakdown Strength Test (ASTM
D149) was carried out, and the results are also listed in Table 1.

As is clear from Table 1, the cured sheet made of only an epoxy resin, a curing agent, and a curing accelerator (Comparative Example 1) had a particularly low tensile strength at break, and also had a low bending strength and dielectric breakdown strength. not enough. Also, cured sheets containing too much heat-resistant thermoplastic resin (Comparative Examples 2, 3, and 4)
has good tensile strength at break and dielectric breakdown strength, but has poor flexibility and poor tensile elongation at break and bending strength. On the other hand, the cured sheets of Examples 1 to 9 obtained by using an appropriate amount of heat-resistant thermoplastic resin in combination with epoxy resin showed no improvement in tensile strength at break, tensile elongation at break, bending strength, and dielectric breakdown strength. Excellent results have been obtained.

[0023]

Effects of the Invention The present invention is constructed as described above, and can provide an inexpensive composition and a heat-resistant insulating sheet or film that provide a sheet or film with excellent flexibility and good heat resistance and insulation properties. is what happened.

Claims (2)

[Claims] Claim 1: (a) 100 parts by weight of an epoxy resin having at least two epoxy groups in the molecule; (b)
A flexible material characterized by containing 1 to 33 parts by weight of at least one heat-resistant thermoplastic resin selected from the group consisting of polyparabanic acid, polyamideimide, and polyimide, and (c) a curing agent having a flexibility imparting effect. A flexible heat-resistant insulating sheet or a composition for sheet production. 2. A flexible heat-resistant insulating sheet or film, which is obtained by molding the composition according to claim 1 into a sheet shape.