JPH0445906A - Manufacture of resin cast material - Google Patents

Abstract

PURPOSE:To form a conductive layer with high accuracy on the surface of a cast material without giving surface processing to the layer by forming a release agent layer on the surface of a mold, coating the same with a conductive film at the given position of said surface and injecting resin. CONSTITUTION:A release agent layer 2 of flourine resin or silicone resin is formed on a cast mold surface of mold 1. Then, a conductive coating material is applied to the given position on the surface of said release agent layer 2, which is heat dried to form a conductive layer 3, and fluidized cast resin is injected into the mold 1 and cured thereon. The cast material is released out of said mold 1 after the resin is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for producing a cast resin article, and particularly to a method for producing a cast resin article having a conductive layer formed on the surface thereof.

(Prior Art) Resin castings generally have excellent insulating performance, and are used in a wide range of fields such as bushings, insulators, and transformer windings.

Among these resin castings, the potential distribution in the resin casting used for high-voltage bushings and windings of high-voltage transformers fluctuates depending on the usage conditions, so it is necessary to equalize this potential. Furthermore, since the surface of the resin casting becomes electrically charged due to electrostatic induction when electricity is applied, it is necessary to prevent electric shock accidents caused by contact with the worker.

Therefore, in this type of resin casting, a conductive layer is formed on the surface and a ground electrode is provided. As a method for forming a conductive layer on the surface of the above-mentioned resin casting, there is a method of casting a thick conductor as a nest, but this method works well when the casting has a simple shape, but If the shape of the mold becomes complicated, there are problems in that the cost of the nest increases and the work process for holding the nest in a predetermined position within the mold becomes complicated.

For this reason, in general, after producing a cast object by pouring resin into a mold, a conductive paint is applied to the part of the surface of the cast object where a conductive layer is to be provided, or a conductive coating is applied by applying metallicon treatment. A method has been adopted to form a In addition, in this method, before coating or metallicon treatment, the surface of the resin casting is scraped thinly using sandpaper or sandblasting, and the release agent adhering to the surface and the layer in which this release agent has been diffused are removed. is being carried out.

(Problems to be Solved by the Invention) However, in the above manufacturing method, when the surface of the resin casting is scraped off with a sand vapor or sandblast, a large amount of dust is generated, which may harm the health of the worker, and may cause problems in the working environment. There's a problem. Furthermore, it is necessary to provide equipment and a dust collector for the removal work, which also poses a problem in terms of cost. Furthermore, the above-mentioned cast product must undergo surface processing operations such as removal of a mold release agent and formation of a conductive layer after demolding, making it difficult to manufacture a product with high precision.

Therefore, the object of the present invention is the above-mentioned 1. Solving the problems of conventional techniques 1 - Manufacture of a resin cast product that can easily and accurately form a conductive layer on the surface of the resin cast product without surface treatment The purpose is to provide a method.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the second object, the present invention forms a mold release agent layer on the surface of the mold, and at a predetermined position on the surface of the mold release agent layer. It is characterized in that a conductive layer coating is applied and a resin cast product is molded in this mold.

(Function) According to the present invention, a mold release agent layer is formed on the surface of the mold (-1) a conductive layer coating is applied to a predetermined position on the surface of the mold release agent layer, and a resin is cast into the mold. Since the product has been molded, the adhesion between the conductive layer coated on the surface of the mold release agent layer and the mold is extremely weak, and in this state, the casting resin is poured into the mold.
Since the adhesive force between the casting resin and the conductive layer is greater than the adhesive force between the mold and the conductive layer, the conductive layer coating adheres to the surface of the resin cast object after the casting resin is completely cured.

As a result, a conductive layer can be formed on the surface of the resin cast product without performing any surface processing work after casting. At this time, since the surface j method of the product depends on the dimensions of the mold, it is possible to obtain a resin cast product on which a conductive layer is formed with high dimensional accuracy.

(Example) An example of the method for manufacturing a resin cast article according to the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 shows an example of a resin casting mold used in the present invention. Reference numeral 1 in the figure indicates a mold, and a mold release agent layer 2 is formed on the inner surface of this mold. Further, a conductive paint is applied in a band shape to a predetermined position on the surface of the release agent layer 2, thereby forming a conductive layer 3.

The above mold is a cylindrical resin casting 4 as shown in Figure 2.
When this cylindrical cast product is used as a bushing, a through hole is bored in the direction of the central axis, and a conductor is fitted into this through hole.

Further, a conductive layer 3 is formed in a band shape on a part of the side surface of the resin cast product 4 over the entire circumference.

Hereinafter, a method for manufacturing a resin cast product having the above-mentioned conductive layer will be explained.

First, a release agent layer 2 is formed on the casting surface of the mold 1.

This mold release agent layer 2 is a coating layer of fluororesin or silicone resin, and is characterized by a low coefficient of friction and non-adhesion. In order to form this coating layer, there is a method in which the above-mentioned resin coating is applied and dried, and then heated and melted to coat the mold.

Next, a conductive paint is applied to the surface of the mold release agent layer 2. The conductive paint preferably has appropriate dispersibility and adhesive properties, and has good wettability to the mold.

After this conductive paint is applied to a predetermined position on the surface of the release agent layer 2, it is kept in a drying oven or the like at a temperature of 100° C. for one hour. As a result, a conductive layer 3 made of a hard conductive film is formed inside the mold with a release agent layer 2 interposed therebetween. This conductive layer must have good adhesion to the casting resin and exhibit long-term stability even after demolding.

This conductive layer 3 is in a state of being attached to the surface of the mold release agent layer 2 as described above, and the adhesive force between this conductive layer 3 and the mold release agent layer 2 is small. The mold in this state] is placed in a fluidized casting resin (
(not shown) is poured into the mold 1, and the casting resin is hardened within this mold 1. This casting resin exhibits strong N1 adhesion to the conductive layer 3 as it hardens, so by removing the casting from the mold 1 after the resin has hardened, the conductive layer 3 can be bonded to the conductive layer 3. It can be integrally formed on the outer periphery.

Next, as another example, a method for manufacturing a resin cast product having a thick conductive layer formed on its surface will be described.

Usually, a conductive layer provided on a resin cast product is formed of a thin film, but there are cases where it is necessary to form a thick conductive layer in order to reduce electrical resistance. In this case, if the coating film of the conductive paint is made quick by the above-mentioned method, the adhesion force with the release agent layer 2 is small, so the conductive layer 5 cannot be held on the surface of the release agent layer 2.

Therefore, FIG. 3 shows an example in which a part of the mold release agent layer 2 was removed and a part of the conductive layer 5 was directly adhered to the surface of the mold. In FIG. 3, reference numeral 5a indicates a conductive layer support portion 1-, and this conductive layer support portion 5a supports the thick conductive layer 5 to the release agent layer 2...resin casting.

can be held on the surface.

Although the shape and number of the conductive layer support portions 5a vary depending on the conductive layer to be formed, they may be of any type as long as they can hold the conductive layer until the casting resin in the mold is cured.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a conductive layer coating is applied to the surface of a mold release agent layer of a mold (12), and a resin cast product is molded in this mold (1). This eliminates the need for surface processing of the resin cast product, eliminates work that generates dust, and provides effects such as the ability to easily manufacture resin cast products with high dimensional accuracy.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing an embodiment of a resin casting mold used in the present invention, FIG. 2 is a perspective view showing a resin casting product manufactured by the mold shown in FIG. Figure 3 shows another embodiment of the invention.1. FIG.

Claims (1)

[Claims] A resin casting characterized in that a mold release agent layer is formed on the surface of the mold, a conductive layer coating is applied to a predetermined position on the surface of the mold release agent layer, and a resin cast product is molded in this mold. Method of manufacturing molds.