JPH0155101B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thin sheet material with excellent heat resistance, electrical performance and oil impregnation properties. More specifically, the present invention provides a novel heat-resistant thin film material by thermocompression bonding an aromatic polyamide synthetic paper and/or an aromatic polyamide nonwoven fabric and an aromatic polyamide film. Aromatic polyamides have excellent heat resistance and mechanical properties, and include p-phenylene terephthalamide, halogen-substituted p-phenylene terephthalamide, m-phenylene terephthalamide, and
-Phenylene isophthalamide-based polymers and m-phenylene isophthalamide-based polymers are polymeric materials that have been widely used in various fields such as fibers and synthetic papers, and have attracted particular attention in recent years. Synthetic paper and nonwoven fabrics made of aromatic polyamides are attracting attention as electrical insulation materials due to their excellent heat resistance, fire resistance, oil impregnation properties, etc. However, the essence of synthetic paper and nonwoven fabrics is their oil impregnation properties. The drawback is that the electrical insulation properties, particularly the electrical breakdown voltage, are proportionally low. On the other hand, although aromatic polyamide films have excellent dielectric breakdown voltage, they do not have oil impregnation properties, which limits their use as electrical insulating materials. One way to solve this problem is m-
A thin sheet material in which a polyethylene terephthalate film is laminated to a phenylene isophthalamide polymer synthetic paper via an adhesive or directly is being considered, but this thin sheet material is limited by the heat resistance of the polyethylene terephthalate film, and aromatic polyamide It cannot fully demonstrate the excellent heat resistance of synthetic paper and nonwoven fabric, and is not necessarily a satisfactory material. Also, an oil-impregnated thin film material for electrical disconnection has been proposed in which a heat-resistant film and an aromatic polyamide synthetic paper or nonwoven fabric are laminated with an adhesive (for example, see Example 1 of JP-A-53-34398). Even in this case, the heat resistance of the adhesive is not necessarily sufficient, and steps such as applying and curing the adhesive are required, so it cannot be said to be an excellent method. Taking these viewpoints into consideration, the present inventors have conducted extensive studies on the development of heat-resistant thin film materials with excellent dielectric breakdown voltage and excellent oil impregnation properties. The present invention was achieved by discovering the fact that a heat-resistant thin sheet material with excellent dielectric breakdown voltage and oil impregnability can be easily obtained without using an adhesive by thermocompression bonding with a crosslinked aromatic polyamide film. This is what I did. That is, the present invention provides an aromatic polyamide synthetic paper and/or an aromatic polyamide nonwoven fabric, and
This is a heat-resistant thin sheet material made by thermocompression-bonding a crosslinked aromatic polyamide film containing one or more crosslinkable compounds. The aromatic polyamide polymer used in the present invention has the general formula

【formula】

It is an aromatic polyamide polymer containing the repeating structural unit represented by the formula either singly or in the form of a copolymer, preferably an aromatic polyamide polymer containing 75% or more of the structural unit. Here, Ar ₁ and Ar ₂ may be the same or different, and have the following structural formula as a typical example.

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] Here, R is lower alkyl, lower alkoxy, halogen or nitro group, n is an integer from 0 to 4 including 0 and 4, and X is

【formula】

【formula】 【formula】

One selected from [Formula], where Y represents hydrogen or a lower alkyl group. The aromatic polyamide-based polymer can be obtained by using a solution polymerization method or an interfacial polymerization method using a predetermined aromatic dicarboxylic acid halide and an aromatic diamine, respectively. The aromatic polyamide synthetic paper used in the method of the present invention is the general method disclosed in Japanese Patent Publication No. 38-13912, etc., and the aromatic polyamide nonwoven fabric is the method disclosed in Japanese Patent Application Laid-open No. 52-46180, etc. Those obtained using the standard methods are used. Further, the aromatic polyamide film used in the method of the present invention is disclosed in Japanese Patent Application Laid-open No. 51-16363 and Japanese Patent Application Laid-open No. 51-1636.
Films can be formed by a dry method such as No. 122167, or a wet method such as JP-A No. 56-41230. The heat-resistant thin film material of the present invention does not use materials that are disadvantageous in heat resistance such as adhesives, so it maintains the original heat resistance of aromatic polyamide and has excellent dielectric breakdown voltage and oil impregnation properties. However, although aromatic polyamide films exhibit a high level of heat resistance, the reality is that they are slightly inferior to aromatic polyimide films in dielectric breakdown voltage, heat resistance, particularly heat deterioration resistance. In response, a new heat-resistant aromatic polyamide film has been proposed in which the heat resistance can be selectively improved by blending a crosslinking compound into aromatic polyamide and treating it with heat, ultraviolet light, and/or electron beams. ing. In the present invention, by using such a new heat-resistant aromatic polyamide film, it is possible to obtain a new thin-sheet material that has significantly better heat resistance, oil impregnation properties, and dielectric breakdown voltage. In the present invention, the following are used as a group of crosslinkable compounds that can be blended with the aromatic polyamide polymer to further exhibit the effects of the present invention. That is, (1) general formula

A group represented by [Formula], and Preferably general formula

A group of compounds containing at least one group represented by the formula: Here, R ₁ , R ₂ .R ₃ represent hydrogen or an alkyl group, and representative examples of such compounds include:
general formula

【formula】

【formula】

There is a group of compounds shown in Here, R ₁ ′, R ₂ ′, R ₃ ′, and R ₄ ′ represent hydrogen, an alkyl group, a hydroxyalkyl group, a carboxyalkyl group, and a halogenated alkyl group, and n is an integer of 1 or more, and R ₁ ′, R ₂ ′, R ₃ ′,
At least one of R ₄ ' must be a radical-reactive functional group such as an unsaturated alkyl group or an allyl group. Representative examples of such compounds include triallyl cyanurate, diallylmethyl cyanurate, polyethylene allyl cyanurate, triallyl isocyanurate, diallylmethyl isocyanurate, ethylene bis(diallyl cyanurate), tetramethylene bis(diallyl cyanurate). ), ethylene bis (diallyl isocyanurate), tetramethylene bis (diallyl isocyanurate), diallyl hydroxyethyl cyanurate, diallyl hydroxyethyl isocyanurate, diallyl carboethoxy cyanurate, diallyl carboethoxy isocyanurate, diallyl chloroethyl cyanurate, diallyl Examples include chloroethyl isocyanurate. Further typical examples include diallyl dicarboxylic acid esters such as diallyl malonate, diallyl succinate, diallyl glutarate, diallyl adipate, and diallyl azelate;
Examples include allyl-substituted melamines such as N,N-diallylmelamine, hexaallyloxymethylmelamine, hexaallylmelamine, and triallylmelamine. (2) General formula

【formula】

A group of compounds containing at least one group represented by the formula: Here, R ₁ , R ₂ , and R ₃ represent hydrogen or an alkyl group, and representative examples of such a group of compounds include:
Acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acids such as methyl methacrylate, ethyl methacrylate, and 2-hydroxyethyl methacrylate, acrylic acid such as ethylene glycol polyethylene glycol, or methacrylate Examples include esters with acids, amides of acrylic acid and methacrylic acid such as acrylamide and methacrylamide, and other general crosslinking compounds can also be used as necessary. 1 selected from the compound groups shown in (1) to (2)
The content of one or more crosslinking compounds is 10% by weight or less, preferably 1 to 5% by weight based on the aromatic polyamide polymer.
The heat resistance of the aromatic polyamide film can be selectively improved by subjecting the film blended in a range of % by weight to heat, ultraviolet rays, electron beams, etc. By thermo-compression bonding the aromatic polyamide film whose heat resistance has been selectively improved and aromatic polyamide synthetic paper and/or non-woven fabric, a novel oil-impregnated thin film material with high heat resistance can be produced without using an adhesive. This is what we provide. Polyimide film is a film with excellent heat resistance and electrical performance, but adhesive is required in order to laminate it with aromatic polyamide synthetic paper, which is the most heat resistant synthetic paper. In contrast, the aromatic polyamide film used in the present invention, which is blended with the crosslinkable compound and subjected to a prescribed treatment, is comparable in heat resistance to polyimide films, and The significance of the present invention is extremely great in that it can provide an oil-impregnated thin sheet material that exhibits the highest heat resistance by thermocompression bonding with aromatic polyamide synthetic paper and/or nonwoven fabric without using an adhesive. . To obtain the thin film material of the present invention, the film and synthetic paper and/or nonwoven fabric can be thermocompressed using a normal laminator, but the linear pressure is 10 kg/cm ~
500Kg/cm, especially 50Kg/cm to 400Kg/cm is preferred. Of course, the optimum range of linear pressure varies depending on the temperature during thermocompression bonding. The thermocompression bonding temperature is preferably 200°C or higher, but from the viewpoint of adhesive strength between the film and the synthetic paper and/or nonwoven fabric, the temperature should be 400°C or higher than the secondary dislocation point of either the synthetic paper and/or nonwoven fabric.
It is preferable to carry out thermocompression bonding at the following temperature. When the film and the synthetic paper and/or nonwoven fabric are bonded together by thermocompression at a temperature above the second-order dislocation point, the two bond extremely firmly, making it possible to obtain a novel heat-resistant thin sheet material. In addition, the secondary dislocation point of the film, synthetic paper, and nonwoven fabric referred to in the method of the present invention may be the polymer alone or in a plasticized state, and may be the secondary dislocation point of the molded article. Any dislocation point is sufficient. In addition, the film, synthetic paper,
The nonwoven fabric is of course an aromatic polyamide polymer, but the film, synthetic paper, and nonwoven fabric may be made of the same aromatic polyamide polymer or different aromatic polyamide polymers, but preferably they are made of the same aromatic polyamide polymer. Group polyamide polymers may be better from the viewpoint of adhesion. The thermocompression bonding operation can be performed either batchwise or continuously. The novel heat-resistant thin sheet material obtained by the present invention has excellent heat resistance and electrical properties, and can be used for various purposes such as electrical insulation materials. Next, the present invention will be explained in more detail with reference to Examples. In addition, all parts in the examples indicate parts by weight. Example 1 Preparation of aromatic polymer solution 90 parts of powder of polymetaphenylene isophthalamide having a logarithmic viscosity ηinh of 1.8 measured at 30°C at 0.5 g/100 ml in 95% sulfuric acid was mixed with N-methyl-2- Dissolved in a solvent consisting of 910 parts of pyrrolidone and 50 parts of water,
A solution of polymetaphenylene isophthalamide was obtained. Preparation of precipitant 75 parts of water was added to 25 parts of N-methyl-2-pyrrolidone to prepare a precipitant. Pulp particle production Consists of a combination of a stator with a bulge and a turbine blade rotor, and a precipitant,
The polymer solution was simultaneously fed at 0.4 kg/mm and the precipitant at 20 kg/mm into a pipe-stirred continuous precipitator equipped with a polymer solution supply port and a pulp particle slurry discharge port after precipitation, and the pulp particle slurry was discharged. I took it out from the exit. At this time, the temperature of the precipitant was adjusted to 35°C, and the temperature of the polymer solution was adjusted to 50°C. In addition, the rotation speed of the rotor was 9600 rpm. The resulting pulp particle slurry was kept at 35°C for approximately
After standing for 30 minutes, most of the precipitant in the Nutsuchie vacuum filter was taken out as a liquid. Then,
Using the same Nutstier vacuum filter, sufficient washing with ion-exchanged water was carried out. Creating a sheet: 6 parts of this pulp particles (solid content) and a single fiber fineness of 1.5
Paper is made using a continuous paper machine from a pulp particle/fiber aqueous dispersion in a mixing ratio of 4 parts of poly-m-phenylene isophthalamide fiber cut into lengths of 7 mm at a denier, and after drying with a drying roller at 120°C, A sheet of 50μ was obtained by continuous processing at a linear pressure of 200Kg/cm using a hot pressure roller set at ℃. Preparation of aromatic polyamide film 20 parts of calcium chloride was dispersed in 200 parts of N-methyl-2-pyrrolidone, and while cooling, 100 parts of poly-m-phenylene isophthalamide and 3 parts of triallyl isocyanurate were added and dispersed to form a slurry. Prepared. After degassing this composition under reduced pressure, it was extruded onto a cast roller at 110°C through a T-die with a width of 0.1 mm and 400 mm using a 30 m/m extruder, and introduced into a 43% calcium chloride aqueous solution at 90°C. Subsequently, after washing in cold water of 10°C or lower, stretching was performed between rollers in a 1.5-fold machine direction in hot water of 95°C. Hold the film at both ends with clips at 95℃ and 100% relative humidity.
The film was stretched 1.7 times perpendicularly at a speed of m/mm, and then dried in a hot air dryer at 150°C and 200°C while holding the length at a constant length with clips to obtain a 25μ film. Further, this film was continuously irradiated with a 2KW high-pressure ultraviolet lamp and then heat-treated for a fixed length in an atmosphere at 350°C to obtain a 25μ film. Lamination The aromatic polyamide synthetic paper and the aromatic polyamide film were laminated through a hot pressure roller set at 290° C. under a linear pressure of 100 kg/cm. Physical Properties of Lamination Sheet The obtained sheet-like material had a thickness of 65μ and exhibited the following properties. Tensile strength: 14.0Kg/mm ^2Dielectric breakdown voltage: 120KV/mm Also, as a result of a 180° peel test of film/synthetic paper, it showed adhesive strength strong enough to break synthetic paper, and had excellent oil impregnation properties. . The early sheet material was tested in a gear aging tester at 200℃ for 500℃.
The strength retention rate after time treatment was over 90%, indicating that it has extremely excellent heat resistance. Example 2 The aromatic polyamide synthetic paper used in Example 1 was replaced with an aromatic polyamide nonwoven fabric. Creation of non-woven fabric Undrawn poly-m-phenylene isophthalamide fibers with a single yarn fineness of 1.5 de cut length 51 mm and the drawn fibers were pre-opened with a single cutter and then flat carded in two stages. A web is formed on a belt conveyor using a cross-laid webber, and then knitted using a knitting machine with a needle density of 84 pieces/cm ² using a 1-barb needle to obtain a fabric weight of 80.
An entangled web of g/m ³ was obtained. Next, the mixture was pressed using a heated roll at a temperature of 280° C. and a linear pressure of 400 kg/cm at a speed of 8 m/min and continuously wound to obtain an aromatic polyamide nonwoven fabric of 70 μm. Physical properties of lamination and lamination sheet Lamination was carried out in the same manner as in Example 1, and the tensile strength was 15.2Kg/mm ² and the dielectric breakdown voltage was 100KV/
A sheet material with excellent adhesive strength and oil impregnability of 1 mm was obtained. The strength retention rate of the sheet material after 500 hours at 200℃ is
90% or more, indicating excellent heat resistance.

Claims (1)

[Claims] 1. Aromatic polyamide synthetic paper and/or aromatic polyamide nonwoven fabric, and one or more crosslinkable compounds having in the molecule at least one organic group represented by the following general formula. A heat-resistant thin sheet material made by thermocompression-bonding a blended and cross-linked aromatic polyamide film. [Formula] [Formula] [Formula] [Formula] (However, R ₁ , R ₂ , and R ₃ represent hydrogen or an alkyl group.)