JP2730119B2 - Insulating paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to an insulating coating which can be used for insulating coatings such as square conductors and which provides an insulating coating having excellent properties such as thermal shock resistance.

B. Summary of the Invention The present invention is intended to add a short glass fiber, fine silica powder and a pigment to an insulating varnish so that the thickness of the coating in the coating process of the insulating varnish can be increased by the usual number of coating processes. In addition, the conductor edge is completely insulated, and the mechanical strength and thermal shock resistance are improved.

C. Prior Art Insulating varnishes are commonly used to apply insulation coating to electrical conductors. This insulating varnish is generally made of polyester resin, epoxy resin, polyimide resin, etc.
One-component or two-component solvent types are used.

D. Problems to be Solved by the Invention However, when insulating a rectangular conductor, etc., a stable coating cannot be obtained, and especially at the edge portion, coating the insulating varnish once or twice completely covers the entire surface. It is difficult and the coating has to be repeated several times.

Conventionally, in order to overcome such difficulties, methods of adding inorganic pigments and thickeners have been used, but these methods are not satisfactory in terms of thermal shock resistance and dispersibility and are not practically satisfactory.

E. Means for Solving the Problems The present invention provides an insulating material that provides a coating having good dispersibility and excellent thermal shock resistance with one or two slight coatings, which could not be solved by a conventionally known method. It is intended to provide paint.

The present invention contains insulating varnish, glass fiber having an average length of 100 to 500 μm, fine silica powder and pigment of 200 to 300 mesh or less, and based on the nonvolatile content of the insulating varnish, the glass fiber is 5 to 40 parts by weight, The gist of the present invention resides in an insulating paint comprising 4 to 10 parts by weight of the fine silica powder and 3 to 10 parts by weight of a pigment.

F. Action The insulating varnish used in the present invention is not particularly limited, and a generally used insulating varnish such as a polyester varnish, an epoxy varnish, or a polyimide varnish is applied. be able to.

In the present invention, the insulating varnish contains a specific amount of a specific glass fiber. The specific glass fiber means a fiber having an average length of 100 to 500 μm. That is, if the average length of the fiber is shorter than 100, the thermal shock resistance is reduced, and 500
If it exceeds μm, the dispersibility of the insulating varnish becomes poor, which is not preferable.

Further, this glass fiber is used for the non-volatile content of the insulating varnish.
It is applied at a ratio of 5 to 40 parts by weight with respect to 0 parts by weight. That is, if the amount is less than 5 parts by weight, the effect is not sufficient, and if it is more than 40 parts by weight, the dispersibility of the insulating varnish deteriorates, which is not preferable.

Further, the insulating paint of the present invention contains a specific fine silica powder. If this powder is too large, the thixotropic effect will be lost. For this purpose, a silica powder of 200 to 300 mesh or less is applied, and this is 100% of the nonvolatile content of the insulating varnish.
It is used in the range of 4 to 10 parts by weight based on parts by weight. That is, if the amount is less than 4 parts by weight, the effect is not sufficient, and
If the amount is more than the weight part, the edge covering property and the thermal shock resistance of the insulating paint are deteriorated, which is not preferable.

Furthermore, the insulating paint of the present invention contains a pigment.
As the pigment, red iron oxide is usually used, but other commonly used pigments such as white titanium may be used. The pigment is used in an amount of 3 to 10 parts by weight based on 100 parts by weight of the nonvolatile component of the insulating paint. That is, when the amount is less than 3 parts by weight, the effect is small, and when the amount is more than 10 parts by weight, the thermal shock resistance of the insulating paint deteriorates, which is not preferable.

In the present invention, the glass fiber improves the mechanical strength and thermal shock resistance of the insulating paint, the fine silica powder prevents the glass fiber from precipitating, and improves the edge covering property of the insulating paint, imparting a so-called thixotropic property. It seems to be effective. It is also considered that the pigment functions as a dispersant and has a function of preventing the fine silica powder from agglomerating.

G. Examples Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

In the following examples, the numbers indicate parts by weight, and the characteristics were evaluated by the following methods.

Dispersibility: Square conductors were immersed in insulating paint, coated, and then visually checked for film formation.

Edge cover property: An insulating paint was applied to a copper bar having a thickness of 0.5 mm, and after curing, an aluminum foil was wrapped around the paint, and the resistance value was measured.

(R> 10 ³ MΩ, 1000V) Thermal shock resistance: Place a spring washer with an outer diameter of 20 mm in the center of an iron container with an outer diameter of 40 mm. It was quenched and checked for cracks every cycle.

Examples 1 to 5 Insulating coatings as shown in Table 1 below were prepared, and their dispersibility, edge cover properties, and thermal shock resistance were examined. Table 1 shows the results and the number of coatings at this time.

Comparative Examples 1 to 5 Insulating coatings as shown in Table 1 below were prepared, and their characteristics were examined in the same manner as in Examples 1 to 5. The results are shown in Table 1.

H. Effects of the Invention As is clear from Table 1, the insulating paint of the present invention contains a specific amount of a specific glass fiber or the like, so that the coating number is about 1 to 2 times and the coating thickness is 2 to 4 times that of a normal coating. A film having excellent edge cover properties and thermal shock resistance can be obtained, and its dispersibility is also good.

Claims (1)

(57) [Claims] 1. An insulating varnish, glass fibers having an average length of 100 to 500 μm, fine silica powder having a mesh size of 200 to 300 mesh or less, and a pigment. An insulating paint comprising 4 to 10 parts by weight of the fine silica powder and 3 to 10 parts by weight of a pigment.