JPS61215020A - Manufacture of thermosetting resin molded member having electrically-conductive surface layer - Google Patents

Abstract

PURPOSE:To enable to display magnetic shielding and antistatic functions effectively for a long period of time without generating deterioration in durability, by a method wherein liquid thermosetting resin having electric conductivity is supplied to the surface of a thermosetting resin molded member manufactured by either a press mold or injection mold, which is made to cure by pressurizing and heating again. CONSTITUTION:A fiber reinforced thermosetting resin molded member 3, for example, is manUfactured by pressurizing and heating thermosetting resin material within a cavity 2 to be formed, for example, for example, of a mold 1. A necessary gap is formed between the molded member 3 and one side part of the mold 1 by breaking the mold 1 and liquid thermosetting resin 5 having electric conductivity is made to flow down to the surface of the molded member through a nozzle 4 inserted into the gap. When the mold 1 is clamped again and pressurizing and heating are performed, the liquid thermosetting resin 5 is made to flow at uniform thickness extending over the whole surface of the molded member 3, stuck firmly to the surface of the molded member and cured. Then an electrically-conductive surface layer having necessary physical properties is formed on the surface of the molded member 3.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a method for manufacturing a thermosetting resin molded article having a conductive surface layer, and in particular, a method for easily forming a highly durable conductive surface layer. It is related to.

(Prior art) Thermosetting resin moldings, especially fiber-reinforced thermosetting resins, have good moldability and can produce molded products with excellent dimensional accuracy, so they are used in construction products, automobile parts, and electrical parts. ,
It has been widely used as a housing for electronics-related equipment.

However, in addition to transmitting electromagnetic waves, thermosetting resin moldings are also electrostatically charged, so if the molded product is used as a housing for electronics-related equipment, for example, it may cause electromagnetic interference to the electronics-related equipment. cause others.

For this reason, it has been proposed to form a conductive layer on the surface of the molded body by, for example, thermal spraying, plating, or vapor depositing a metal, thereby making the molded body a magnetic shielding structure. There is.

(Problems to be solved by the invention) However, with any of these proposed technologies,
In addition to requiring special equipment and processes, there are problems in that productivity is poor.Moreover, there are problems in that the adhesiveness between the surface of the resin molded product and the conductive layer is poor, and the durability of the conductive layer is low.

The present invention advantageously solves the problems of the prior art, and provides a conductive surface layer that can be easily formed under the action of existing molding dies, instead of having poor durability. The present invention provides a method for producing a thermosetting resin molded article having the following properties.

(Means for Solving the Problems) The method for producing a thermosetting resin molded body having a conductive surface layer according to the present invention is a method for producing a thermosetting resin molded body having a conductive surface layer. A first step of supplying a conductive liquid thermosetting resin onto the surface of the molded body, with or without taking out the molded body from the mold, and then re-doping them in the same mold as the above-mentioned molding die. and a second step of curing the liquid thermosetting resin by applying pressure and heating.

(Function) In this method, the conductive thermosetting resin is extremely easily applied to the surface of the molded product in the first step, and the second step
In this process, the conductive thermosetting resin is flowed to a nearly uniform thickness over the entire surface of the resin molded body, and is firmly fixed to the molded body surface, thereby eliminating the conductive surface layer that has lost its durability. , it can be easily molded without the need for special equipment.

(Example) The present invention will be explained below based on illustrated examples.

FIG. 1 is a cross-sectional view showing the manufacturing process of a thermosetting resin molded body, in which, for example, a thermosetting resin material is pressurized and heated in a cavity 2 formed by a press molding die 1. In this way, for example, a fiber-reinforced thermosetting resin molded body 3 is also produced.

Here, the heat curing time of the resin material is preferably longer than the gel time of the resin, and the monthly yield of the resin is based on unsaturated polyester containing short glass fibers, fillers, curing agents, etc. , epoxy resin, etc. are used.

FIG. 2 is a cross-sectional view illustrating the first step of the invention,
Here, by completely opening the molding die 1,
Alternatively, by opening the mold by a few millimeters or several centimeters, a required gap is created between the molded body 3 and one part of the molding die 1, and the nozzle 4 inserted into the gap is used to apply conductivity to the surface of the molded body. A liquid thermosetting resin 5 having properties is caused to flow down.

Note that the liquid thermosetting resin 5 can also be poured onto the surface of the molded article without applying it or using a nozzle.
Furthermore, it is also possible to inject using an injector attached to the mold. Moreover, it can also be applied to the surface of the molded body after the molded body 3 is taken out from the molding die 1.

In addition, as the thermosetting resin used for this purpose, polyurethane (one-component or two-component heating type), unsaturated polyester, vinyl ester, etc. can be selected, and among them, urethane-based resins can be selected. It's sagging. Furthermore, in order to provide conductivity to this thermosetting resin material, conductive materials mixed therein include carbon blank metal powder,
metal fiber.

Carbon fiber, conductive fiber, metal-coated glass fiber, metal oxide, etc. can be selected, and their shapes are
spherical,! It may be either 4-shaped or short fibrous. The mixing ratio of such conductive materials to the resin monthly rate is 10 to 80%.
It can be set as an appropriate proportion by weight, and can be determined based on the conductive material used, the required conductive performance, and the like.

FIG. 3 is a cross-sectional view illustrating the second step of the present invention, in which the molding die 1 is closed again and, in particular, the liquid thermosetting resin 5 is pressurized and heated to make it thermosetting. The resin 5 is flowed to a uniform thickness over the entire surface of the molded body 3 and is cured while firmly adhering to the surface of the molded body 3, so that the surface of the molded body 3 has the required physical properties. A conductive surface layer will be formed. Resin 5 here
The curing time is generally 2 to 5 minutes, which is the time required for it to be cured to a hardness that is not easily damaged.

Note that the thickness of the conductive surface layer formed of the thermosetting resin 5 can be adjusted by controlling the supply amount of the liquid thermosetting resin and the pressure of the molding die.

Furthermore, FIG. 4 is a cross-sectional view showing the product taken out from the molding die. It has a layer 5a.

Therefore, according to this embodiment, by using the existing molding die 1 without requiring any special equipment or equipment, the durable conductive surface is firmly fixed to the molded body 3. The layer 5a can be formed extremely easily.

Although the case where the conductive surface layer 5a is formed on the fiber-reinforced thermosetting resin molded body 3 has been described here, according to the present invention, the same conductive surface layer 5a can also be formed on a molded body that is not reinforced with fibers. Of course, it can be molded.

Test results of products manufactured by the method of the present invention will be explained below.

[Test Example 1] First, as a fiber-reinforced thermosetting resin, a commercially available sealant made of unsaturated polyester resin was used as a base material.
Using a molding compound, 600 g of the molding compound was supplied into a molding die (300 mm x 300 mm flat plate mold) and press-molded to obtain a molded body. At this time, the mold temperature was 140°C, the pressure was 50 kg/cJ, and the curing time was 2 minutes.

Next, the mold was opened and 30 g of a two-component polyurethane resin containing 40% by weight of nickel powder with an average particle size of 16 μm was allowed to flow down onto the surface of the molded body, and then the mold was closed again. The molded product was pressed for 3 minutes at the same temperature and pressure twice to form a conductive surface layer on the surface of the molded product.

As a result, a fiber-reinforced thermosetting resin molded article having a conductive surface layer with an electrical resistance of 108 Ω was obtained.

[Test Example 2] 70% by weight of tin oxide powder (scaly, long diameter 2 μm, thickness 0.1 μm) as a conductive liquid thermosetting resin
Molding was carried out under the same conditions as in Test Example 1, except that the two-component polyurethane resin contained therein was used.

The electrical resistance value of the conductive surface layer of the fiber-reinforced thermosetting resin molded article thus obtained was 104Ω.

[Test Example 3] Molding was carried out under the same conditions as Test Example 1, except that a one-component polyurethane resin containing 20% by weight of carbon blank was used as the conductive liquid thermosetting resin. I did it.

As a result, a fiber-reinforced thermosetting resin molded article having a conductive surface layer with an electrical resistance of +03Ω was obtained.

(Effects of the Invention) Therefore, according to the present invention, the electrical resistance can be reduced from 10° to 10° without using a painting line or other special equipment or process.
A 108 Ω conductive surface layer can be formed extremely simply, and since the conductive surface layer firmly adheres to the surface of the thermosetting resin molding, there is no possibility of deterioration in durability due to peeling or other factors. It is possible to exhibit magnetic shielding and antistatic functions sufficiently effectively over a long period of time without causing any damage.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views illustrating steps for implementing the present invention, respectively. 1... Molding mold 2... Cavity 3...
・Fiber-reinforced thermosetting resin molded body 4... Nozzle

Claims (1)

[Claims] 1. A step of supplying a conductive liquid thermosetting resin to the surface of the thermosetting resin molded body produced in the molding die, and pressurizing and heating these in the molding die to form the thermosetting resin molded body. A method for producing a thermosetting resin molded article having a conductive surface layer, comprising the step of curing a liquid thermosetting resin.