JPS6144363B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a prepreg for electrical insulation, such as exterior insulation for electrical coils.

Conventional prepreg for electrical insulation is made by impregnating a woven fabric base material with a semi-cured thermosetting resin, which is wrapped around the surface of an electric coil and heated to harden to form a predetermined insulating layer. do. However, during heat curing, the resin that has softened and flowed tends to penetrate and migrate to the adherend, which may cause the resin to be completely or partially missing, resulting in poor electrical properties. In particular, when applying fabric tape such as cotton tape or Tetoron tape for binding purposes before wrapping the prepreg,
The resin is absorbed into this, and the above-mentioned drawback becomes noticeable.

In order to avoid this drawback, attempts have been made to increase the viscosity during softening and flow by adjusting the semi-cured state of the thermosetting resin, but such adjustment is not only very troublesome, but also increases the viscosity. If the penetration and transfer to the adherend is excessively suppressed by this method, poor adhesion between the adherend and the cured insulating layer may occur, and the prepreg itself may become too hard, which may impede winding workability. Most likely.

This invention was discovered as a result of intensive studies from this point of view, and its gist is to use a polymer with good flexibility and aim for a polymer adhesion amount of 5 to 100 g/ ^m2 . This is an electrically insulating prepreg made by impregnating and adhering a semi-cured thermosetting resin to a woven fabric base material that has been treated with a sealant.

That is, in this invention, before impregnating and adhering the thermosetting resin to the woven fabric base material, the base material is sealed in advance with a polymer having good flexibility, thereby impairing the adhesion to the adherend. The inventors have discovered that it is possible to effectively suppress the permeation and migration of the resin during heat curing without any heat curing, thereby forming an insulating layer with excellent electrical properties.

The woven fabric base material used in this invention includes inorganic fibers such as glass fibers, organic fibers with good heat resistance such as aromatic polyamide, polyester, nylon, vinylon, and polypropylene, or mixtures of inorganic fibers and organic fibers. A wide variety of fibers are included. It may also be heat-shrinkable, particularly preferably heat-shrinkable only in one direction. The thickness of such a woven fabric base material is usually 0.03 to 0.3 mm, and the number of vertical and horizontal strokes is generally about 10 to 60 per dimension.

The polymer used for sealing the woven fabric base material may be any polymer that has good flexibility and heat resistance depending on the base material, such as thermosetting resin such as modified epoxy resin, saturated polyester resin, etc. ,
Any of polyamide resin (nylon), thermoplastic resin such as vinyl chloride resin, and rubbery polymer such as nitrile rubber can be used. The thermoplastic resin or rubbery polymer needs to have a softening temperature at which it will not soften and flow when the resulting prepreg is heated and cured.

The sealing treatment is performed by impregnating and coating one or both sides of the woven fabric base material with a solution containing each of the above resins and containing fillers and other additives as necessary, or by dipping, and then heating and drying. However, when a thermosetting resin is used, it is almost completely cured during heating and drying.

The amount of polymer attached by sealing treatment is 5 to 100.
g/m ² , particularly preferably between 15 and 50 g/m ² .If it is less than 5 g/m ² , the effect of this invention cannot be obtained, and if it exceeds 100 g/m ² , it will not be effective. This is unsuitable because the properties of the blocking resin will affect the performance of the cured insulating layer. The amount of this polymer deposited is usually 5 to 40% by weight, preferably 15 to 25% by weight of the total resin together with the thermosetting resin impregnated and deposited each time.

The electrical insulating prepreg of the present invention is made by impregnating a woven fabric base material that has been sealed in this way with a thermosetting resin in a semi-cured state, and the thermosetting resin used here is phenol. Any of the conventionally known resins can be used, such as polyester, epoxy, polyester, diallyl phthalate, and modified products of these resins. This resin may contain fillers and other additives in addition to the curing agent. In addition, the method for impregnating it into a semi-cured state is arbitrary, and generally, it is impregnated by a method such as dipping with an organic solvent solution or brushing on one or both sides, and then heated and dried under conditions that result in a semi-cured state. Bye.

Next, examples of the present invention will be described in more detail. Note that in the following, parts and % mean parts by weight and % by weight.

Example: Thickness 0.1mm, number of implants (vertical x horizontal) 30 x 40/
Glass woven fabric (Product name SEL made by FRP Kogyo Co., Ltd.)
100) was impregnated with a solution prepared by diluting a modified epoxy varnish (Toshiba Corporation's cloth pipe varnish, trade name #96A) to 15% with industrial gasoline No. 4 using the dipping method, and then heated at 150°C for 20 minutes. A sealed glass woven fabric having a cured polymer adhesion amount of 20 g/m ² was obtained by heating and drying.

Next, on this sealed glass woven fabric,
30 parts of bisphenol type epoxy resin (product name Epon#1001 manufactured by Yuka Ciel Epoxy Co., Ltd.) and 30 parts of epoxy novolac type resin (trade name manufactured by Yuka Ciel Epoxy Co., Ltd.)
Epon #154) 70 parts and 3 parts of boron trifluoride monoethylamine complex salt dissolved in a 1:1 mixed solvent of methyl ethyl ketone and toluene were impregnated with a 40% solution by the dipping method, and dried by heating at 90°C for 20 minutes. ,
The electrical insulation prepreg of this invention was prepared. The amount of resin attached to this prepreg (including the sealing polymer) was 120 g/m ² .

Next, wrap a 19 mm wide raw Tetron tape once in a half-wrap for tightening around the coil with an inner diameter of 200 mm, an outer diameter of 300 mm, and a thickness of 50 mm, and then wrap the above prepreg 19 mm in length so that the vertical direction is the longitudinal direction.
A tape-shaped material cut to width was wrapped twice with a half wrap, and then heated and cured at 130° C. for 16 hours in a hot air dryer. When we cut and dismantled this cured insulating layer, we found that the raw Tetron tape layer and the cured insulating layer had good adhesion, and the surface resin layer also had a uniform and glossy appearance. No varnish treatment was required at all. The dielectric breakdown voltage of the coil coated with insulation in this way was over 10KV, showing good electrical properties.

In addition, if sealing treatment was not performed in the above example, almost all of the epoxy resin in the prepreg would be absorbed into the raw Tetron tape layer in the same test as above, and the dielectric breakdown voltage would be less than 1KV, making it impractical for practical use. I couldn't offer it. For this reason, after the prepreg was wrapped and cured by heating, a varnish finishing treatment was required as a post-treatment.

Claims (1)

[Claims] 1 Prepreg for electrical insulation made by impregnating a semi-cured thermosetting resin into a woven fabric base material that has been sealed using a polymer with good flexibility so that the amount of polymer adhesion is 5 to 100 g/m ² .