JPS6039025B2 - Heat-resistant insulation board and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention also relates to an insulating board used as an insulating material for equipment such as motors and transformers, and particularly to a heat-resistant insulating board used for insulation between coils of transformers of class H or higher.

Pressboard made of pulp has traditionally been used as an insulating material for equipment such as motors and transformers, but with the recent technological trend of miniaturizing large-capacity transformers, the heat resistance of insulation materials has increased to over 18,000. It's starting to be demanded.

Therefore, a heat-resistant insulating board made by stacking an appropriate number of sheets of fully aromatic polyamide synthetic paper, which is known as a heat-resistant insulating material, and heating and pressurizing it has been considered. However, since this wholly aromatic polyamide synthetic paper is a dense aggregate of fibrids, the size of the voids is very small, making it difficult to completely impregnate the voids with insulating oil such as silicone or varnish. There are many unimpregnated areas, and there are disadvantages in that corona is generated in these areas, causing a decrease in the corona onset voltage characteristics and eventually in the withstand voltage characteristics, or the structure deteriorates due to moisture absorption from the unimpregnated areas. Ta.

In addition, the insulating board having a top layer of wholly aromatic polyamide paper is rigid and has the disadvantage that it is difficult to mold it to match the shape of the coil. Furthermore, it also has the disadvantage that the laminated layers may peel off. In view of these points, the present invention improves the oil receptivity of the insulating oil by interposing a bulky and flexible fiber laminated layer between the heat-resistant film or the heat-resistant paper, thereby improving the corona onset voltage characteristics and improving the insulation. This reduces the hygroscopicity of the board and improves moldability.

That is, the present invention is a heat-resistant insulating board comprising an outermost layer made of a heat-resistant film or paper and an intermediate layer made of a heat-resistant fiber laminated layer.

To explain the present invention in more detail, the heat-resistant film used as the outermost layer includes a polyethylene naphthalate film, a wholly aromatic polyamide film, a polyimide film, and a tetrafluoride film. There are ethylene films, phenol films, etc. As the heat-resistant paper, glass paper or asbestos paper impregnated with a semi-cured resin such as wholly aromatic polyamide synthetic paper, polyesterimide resin, polyamideimide resin, silicone resin, or wholly aromatic polyamide resin is used. As the heat-resistant fibers used for the intermediate layer, wholly aromatic polyamide fibers or polyester fibers having a fiber length of about 1 c or more are used.

Heat-resistant fibers are not fine particles like the fibrils that make up heat-resistant paper, but are more than about 1 cm in length.
Even if these are accumulated and compressed, the filling effect is poor, and unlike paper, the size of the voids is not small, and a fiber stack is obtained in which a large number of fibers are entangled at their intersections to form large voids. Therefore, the heat-resistant fiber laminated layer, which is the intermediate layer, is bulky and flexible, so it has excellent impregnability with insulating oil and excellent bendability. A method of integrating the outermost layer and the intermediate layer is to layer a fiber lamination layer such as nonwoven fabric or fiber web on heat-resistant paper or the like coated with adhesive, and then heat-resistant paper with adhesive coated on top of it. It can be integrated by stacking papers etc. and applying pressure.

A particularly useful method for integrating is the second invention, in which heat-resistant paper or the like is layered on both sides of a fiber web containing heat-adhesive heat-resistant fibers, and heat and pressure are applied to the fiber web. This method is characterized in that the constituent fibers of the fibrous web and the heat-adhesive heat-resistant fibers are bonded to a heat-resistant film or heat-resistant paper by softening the heat-adhesive heat-resistant fibers. As the heat-adhesive heat-resistant fibers, undrawn aromatic polyamide fibers, undrawn or drawn polyester fibers are used. The fibrous web may be formed by using these heat-adhesive heat-resistant fibers alone, or by mixing them together. When a fiber web is formed by mixing, for example, when a fiber wafer consisting of undrawn aromatic polyamide fibers and undrawn polyester fibers is formed,
Both can be used as heat-adhesive fibers by heating and pressurizing them to the extent that they have heat-adhesive properties.
By heating and pressurizing the undrawn polyester fibers to such an extent that only the undrawn polyester fibers have heat adhesive properties, only some of the fibers can be used as heat adhesive fibers. Alternatively, a fiber web may be formed by mixing these heat-adhesive fibers and aromatic polyamide fibers. The fiber web used in the present invention has fibers accumulated,
Any type of sheet may be used, but one that has mechanical strength because the constituent fibers are entangled or some of the constituent fibers are softened and bonded together. It is preferred because it is easy to handle. Heat-resistant paper or the like is laminated on both sides of the fibrous web thus formed, and a press machine heats and pressurizes it with a calendar roll to soften the heat-adhesive fibers in the fibrous web and create an interlayer between the constituent fibers in the fibrous web. By adhering heat-resistant paper or the like to heat-adhesive fibers, an insulating board in which the intermediate layer and each layer are firmly integrated can be obtained.

In the present invention, not only the three-layer structure of the outermost layer, the middle layer, and the outermost layer, but also the five-layer structure, such as the outermost layer, the middle layer, the outermost layer, the middle layer, and the outermost layer, or even the seven-layer structure You can also make one.

The product of the present invention obtained in this manner has an intermediate layer composed of an accumulated layer of heat-resistant fibers, is bulky, has large voids compared to paper, etc. that constitutes the outermost layer, and is difficult to transport. Since there are no impregnated parts, the corona starting voltage characteristics are improved. Moreover, since the outermost layer is made of film or paper and the structure is dense, it has excellent electrical resistance properties. Since the fiber laminated layer is very flexible and responds arbitrarily to bending, it can easily be molded into L-, U-, and U-shaped collars that could not be molded with conventional insulating boards laminated with delicate paper. In addition, in the product of the present invention obtained by the second method of the present invention, the outermost layer and the intermediate layer are firmly integrated, so that the layers do not peel off during handling such as molding. As described above, the product of the present invention has excellent properties, and therefore can be used not only for insulation between coils of transformers of class H or higher, but also for various other insulation applications.

The present invention will be explained below based on examples. Example 1 2.5 denier, 38 weight undrawn aromatic polyamide fibers were accumulated and formed into a sheet, and this was needle-punched to obtain a fiber web with a basis weight of 1300 g/a, in which the fibers were entangled, and on both sides of this Thickness 23 mil, basis weight 200g/
Arranged with that aromatic polyamide paper, 25,000, 50kg/
It was pressed for 15 minutes using a press under those conditions.

At this time, the undrawn aromatic polyamide fibers constituting the intermediate layer are softened, and the drawn aromatic polyamide fibers are bonded to each other, and the undrawn aromatic polyamide fibers and the aromatic boryamide paper are bonded to become strong. A heat-resistant insulating board integrated with the was obtained. The physical properties of the insulation board are shown in the table. Example
2 A mixture of 2.5 denier, 38-weight undrawn aromatic polyamide fiber and 5-denier, 38-weight undrawn polyester fiber in a weight ratio of 90:10 was assembled and formed into a sheet, and this was made into a sheet of 20,000 sheets. Only the undrawn polyester fibers are passed through a aging oven to melt them, and then passed through a nip roll to entangle the drawn aromatic polyamide fibers to obtain a fiber web with a basis weight of 1460 g.

Prepare two sheets of this fiber web, thickness 23 mil, basis weight 20.
0g/That aromatic polyamide paper - fiber web - thickness 10
Mill, basis weight 80g/that aromatic polyamide paper - fiber wafer-thickness 23 mil, basis weight 200g/that aromatic polyamide paper were laminated in this order and pressed under the same conditions as Example 1,
A strongly integrated five-layer insulation board was obtained. The physical properties of this insulating board are shown in the table. Example 3 A semi-cured (B stage) glass vapor with a fabric weight of 130 g/m (base fabric weight of 50 g/m) was prepared by impregnating a polyesterimide resin instead of the aromatic polyamide paper of the outermost surface layer used in Example 2. was placed and pressed under the same conditions as Example 2.

The surface layer of the obtained insulating board formed a film-like layer with a porosity of 0%, and the insulating oil was impregnated into the intermediate fiber stack layer from the side surface of the insulating board. The physical properties of the insulation board are shown in the table. table

Claims (1)

[Scope of Claims] 1. A heat-resistant insulating board comprising an outermost layer made of a heat-resistant film or paper and an intermediate layer made of a heat-resistant fiber laminated layer. 2 Laminating a heat-resistant film or heat-resistant paper on both sides of a fibrous web containing heat-adhesive heat-resistant fibers, and applying heat and pressure to soften the heat-adhesive heat-resistant fibers. 1. A method for producing a strongly integrated heat-resistant insulating board, which comprises bonding between the constituent fibers and bonding the heat-adhesive heat-resistant fibers and a heat-resistant film or heat-resistant paper.