JPS61220813A - Molding of plastic - Google Patents

Abstract

PURPOSE:To provide the molding method of the molded piece of plastic, which is provided with electrical conductivity, by a method wherein either one of electrically conductive powdered resin composition or electric radiation absorbing powdered resin composition is coated to the inside of a mold by electrostatic coating and the other powdered resin composition is coated thereon through the electrostatic coating, thereafter, the plastic is molded. CONSTITUTION:A masking material 5 is fixed to the unnecessary section of the fixed mold 3a. The electric radiation absorbing powdered resin composition 2a is coated on the surface of the fixed mold 3a by an electrostatic coating machine 6. Subsequently, the electrically conductive powdered resin composition 4a is coated thereon by the electrostatic coating machine 6'. The masking material is removed and coated powdered resin compositions 2a, 4a are plasticized by heating if necessary. A movable mold 3b is put on the fixed mold 3a and the mold is closed, then, molten plastic material is cast into the cavity of the mold through a filling hole 3b' to anchor and adhere an electrical conductive film 4 and an electric radiation absorbing film 2 on the surface of the molded piece 1 of plastic. The mold is opened and the molded piece 1 is taken out of the mold.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a method for forming a conductive film and a radio wave absorbing film formed on the surface of a plastic molded product, or a radio wave absorbing film and a radio wave absorbing film formed thereon. The present invention relates to a plastic molding method for forming a multilayer coating consisting of a conductive coating. Specifically, the present invention relates to a method for obtaining a plastic molded body having the purpose of shielding electromagnetic waves, preventing static electricity, etc.

(Prior art) In recent years, it has become clear that malfunctions in electronic equipment using semiconductor devices are caused by TM waves and static electricity. Regulations regarding devices are beginning to be enacted into law, and the electronic device industry is urged to take countermeasures.

Currently, one method of shielding these sources of interfering tMI waves is to knead s'rtz powder into plastic and then mold it, giving the plastic molded body itself a conductive function (for example, No. 35-9643) is known. However, while this method has the advantage of being easy to work with, it requires the inclusion of a large amount of conductive powder in order to obtain an electrical conductor, which results in a decrease in the physical strength of the plastic after molding, and an increase in weight. It has not been put into practical use much because of various other drawbacks such as increase in size and problems in molding.

Another known shielding method is to apply a solvent-soluble conductive paint to the inner surface of an electronic device housing with a brush or spray.

In this method, it is necessary to take measures against shape damage and discoloration caused by the organic solvent contained in the conductive paint, as well as overcoat measures to improve the adhesion strength of the paint film and prevent paint film peeling.
There were problems such as odor caused by volatilization of organic solvents into the atmosphere, adverse effects on the human body, and dangers such as fire.

Recently, after painting a solvent-soluble conductive paint with a brush or spray gun into a mold for electronic device housing, the plastic is molded inside the mold, and the plasti-7 molded body and conductive coating are integrated. A method has also been proposed (for example, Japanese Patent Publication No. 4B-25061). According to this method, a grease-like composition is applied inside the mold, a conductive powder such as graphite is sprayed on top of the composition, and then a liquid synthetic resin is injected and cured to make the predetermined areas conductive. A method has been proposed for obtaining an insulating molded body with high properties. However, this method has the fundamental problem that the conductive powder has weak adhesion at points other than the points of contact with the grease-like composition, so careful attention is required when injecting the resin, and in addition, the injection speed is also limited. There were operational problems such as the fact that it was extremely slow.

Therefore, this method cannot be applied to high-speed molding methods such as injection molding methods.

In addition, the above-mentioned known document also describes a method of using a synthetic resin adhesive before resin injection in order to increase the adhesion of the conductive powder, but if this method is adopted, the aforementioned solvent can be removed. None of the problems associated with applying a melt-molded conductive paint after molding have been solved.

In general, as a means to solve the above-mentioned problems of solvent-soluble paints, it is conceivable to use, for example, powder paints that do not contain any solvent at all.

In fact, in the field of molding as well, powder coatings containing a small amount of ordinary colored pigments are heated and applied to the inner surface of a pressure mold in advance by a fluidized bed or spray, and then compression molded using SMC or BMC. A method of forming a protective or colored film on the surface of FRP is known (for example, Japanese Patent Publication Nos. 44459/1982, 181823/1982, and 124610/1982).

However, even with these methods, there are problems such as powder scattering, adhesion to the outside of the mold, and uneven film thickness.

On the other hand, conductive films have the ability to reflect electromagnetic waves, but do not have the ability to absorb them (and are not effective in shielding electromagnetic waves in the high frequency range (low wavelength)).

Furthermore, since conductive coatings are conductive, if they are exposed inside an electronic device housing, there is a high risk of electric shock or leakage due to contact with internal devices carrying current. This can also be cited as one of the problems.

(Problems to be Solved by the Invention) The present invention solves safety and hygiene problems caused by organic solvent volatilization, and problems such as scattering of powder paint, adhesion to the outside of the mold, and uneven film thickness. A powdered resin composition containing a high concentration of conductive fine powder can be efficiently and uniformly adhered to a plastic surface to form a conductive plastic molded product with a surface resistance value of about 10" ohms or less. It attempts to provide a method.

Furthermore, it is an object of the present invention to provide a plastic molding method for forming a multilayer coating having a radio wave absorbing coating that absorbs electromagnetic waves in the high frequency range and, in some cases, has the function of preventing electric shocks and leakage accidents caused by conductive coatings.

(Means for Solving the Problems) That is, the present invention provides a plastic molding method in which first, a powdery resin composition of either a conductive powdery resin composition or a radio wave absorbing powdery resin composition is used. It is applied into the mold by electrostatic coating, and then the other powdered resin composition of the powdered resin compositions is applied thereon by electrostatic coating, and then the plastic is molded, and a conductive film and an insulating film are formed. The present invention relates to a plastic molding method in which a multilayer film consisting of a film is brought into close contact with the surface of a plastic molded body.

(Detailed Description of the Invention) The conductive powder resin composition used in the method of the present invention is a thermosetting or thermoplastic resin composition containing conductive fine powder.

Examples of the thermosetting resin include acrylic resin, polyester resin, epoxy resin, alkyd resin, urethane resin,
Examples include epoxy modified polyester resin and acrylic modified polyester resin. In particular, acrylic resins, polyester resins, and epoxy resins are preferred from the viewpoint of storage stability and conductivity of the coating film.

Various types of thermosetting resins can be used, such as a self-curing type and a curing agent (crosslinking agent) curing type.

As the curing agent for the thermosetting resin, dicyandiamide, acid anhydride, imidazole derivative, aromatic diamine,
Boron trifluoride amine compounds, hydrazides, decamethylene dicarboxylic acid, blocked isocyanate compounds,
Those normally used for thermosetting powder coatings, such as amino resins, can be used.

Further, as the thermoplastic resin, polyester resin,
Known materials include polyethylene, polypropylene, styrene polymers, vinyl chloride polymers, polyamide resins, butyral resins, cellulose resins, petroleum resins, and the like.

The thermosetting resin and the thermoplastic resin can be used individually or as a mixture, or if necessary, the thermosetting resin and the thermoplastic resin can be used in combination.

In the present invention, the resin component used in the powdered resin composition has a softening point of 40 to 160°C and a melting point of 60 to 180°C.
, preferably a softening point of 60-130°C, a melting point of 70-160°C
It is about ℃.

The softening point was measured by Kofler's method, and the melting point was measured by Durran's method.

, and the conductive fine powder includes gold, platinum, palladium,
Metal powders or alloy powders such as silver, copper, and nickel; electrically good materials such as inorganic powders that are electrically poor conductors, such as nickel-coated mica powder, or plastic powders whose surface is coated with metals that are good electrical conductors. It is a conductive fine powder with a particle size range of 0.5 to 100 μm, preferably about 1 to 50 μm. These powders can be used alone or in combination of two or more.

Dendritic metal fine powder is particularly effective for the purpose of the present invention, that is, to obtain a film with good conductivity and excellent adhesion.

The conductive fine powder is preferably contained in the conductive powder resin composition in an amount of 70 to 95% by weight, more preferably 75 to 90% by weight.

In the present invention, the conductive powder resin composition includes a composition in which all of the conductive fine powder is encapsulated in each individual resin powder, a resin powder in which most of the conductive fine powder is contained, and a resin powder in which a small amount of the conductive fine powder is contained. A mixture of conductive fine powders (provided that the total amount of conductive fine powders is within the above range). In the latter case, it is natural that the electrical resistance in the powder state must be high enough to allow electrostatic coating.

If the amount of conductive fine powder in the conductive powder resin composition is less than 70% by weight, a good conductive film cannot be formed on the surface of the plastic molded product, whereas if it exceeds 95% by weight. Since it becomes difficult to perform electrostatic coating efficiently, neither of these methods is particularly preferred.

The conductive powder resin composition used in the method of the present invention is
It is obtained by a known powder coating manufacturing method.

For example, a mechanical pulverization method in which the resin and conductive powder, and other necessary hardening agents, additives, etc. are heated and melted and mixed, and then cooled, pulverized, and sieved; In addition, if necessary, a dry spray method can be applied in which a curing agent, additives, etc. are dispersed in a solvent, and then the resulting dispersion is sprayed into heated air.

Therefore, when obtaining a composition containing conductive fine powder at a higher concentration, when using a resin with a low melting point, or when considering prevention of agglomeration of a powdered resin composition, the following wet granulation method is used. A manufacturing method using a method is preferred.

For example, the resin is dissolved in a water-soluble solvent (preferably having a solubility in water of 10 to 30% by weight at 20°C) such as alcohols, ethylene glycol derivatives, diethylene glycol derivatives, esters, and ketones, and then A liquid composition (hereinafter referred to as dispersion) obtained by mixing the resin, conductive fine powder, and other necessary hardening agents, additives, etc., is prepared so that all the water-soluble solvent contained in the dispersion is Dissolve! Emulsify and disperse in water (approximately 3 to 40 times the volume of the dispersion). Emulsification is carried out by dropping, pouring, or spraying the dispersion into water under vigorous stirring, or by mixing water and the dispersion using a line mixer.

The above-mentioned stirring or mixing using a line mixer is carried out until the solvent in the emulsion fine particles is transferred into water and particles are formed.

In this way, the solvent in the emulsion fine particles is extracted into water, and resin particles are obtained.

The resin particles are separated from the water-solvent mixture by filtration or centrifugation, and if necessary, water washing and separation are repeated a necessary number of times to obtain resin particles in the form of a slurry or a water-containing cake. Then, if necessary, use a ball mill, bot mill,
After granulation with a sand mill or the like, the resin particles are dried to prevent agglomeration, preferably by freeze drying, vacuum drying, etc., and if necessary, sieved to obtain the conductive powder resin composition of the present invention. Such manufacturing methods are described, for example, in Japanese Patent Application Laid-open No. 48-52851, Japanese Patent Publication No. 54-5832, and Japanese Patent Publication No. 54-54.
-26250, 54-31492, 56-57
No. 96 and No. 56-29890.

Further, the particle size range of the conductive powder resin composition used in the method of the present invention is about 0.5 to 100 μm, preferably about 1 to 50 μm.

On the other hand, the radio wave absorbing powder resin composition used in the method of the present invention is a thermosetting or thermoplastic resin composition containing radio wave absorbing fine powder.

The resin as a color vehicle used in the electromagnetic wave absorbing powder resin composition of the present invention is entirely thermosetting or suspension resin similar to that used in the conductive powder resin composition. It can be used without any problems. Further, as a method for producing the radio wave absorbing powdered resin composition, a method similar to the method for obtaining the conductive powdered resin composition described above can be applied.

In particular, when obtaining a resin composition containing a high concentration of radio wave absorbing fine powder, or when considering prevention of agglomeration of the radio wave absorbing powder resin composition, the production method using the wet granulation method is preferable. .

The softening point and melting point of the resin used in the radio wave absorbing powdered resin composition, as well as the particle size of the resin composition, etc., may be within the same range as in the case of the powdered resin composition with the above i'. preferable.

As the radio wave absorbing fine powder used in the radio wave absorbing powder resin composition, spinel type ferrite particles represented by the general formula % (representing a divalent metal) are preferred.

Such particles include, for example, N iF e to ZnFe, O. , M n F e toa, CuFez
O4, Fe, O, CoFezOa, etc., or Ni-
Examples include composite ferrites such as Zn, Ni-Mn, and Mn-Zn. These may be used alone or as a mixture of two or more.

The method for producing the spinel type ferrite +-a particles includes -
It can be obtained by a method known in the art, for example, the method described in "Powders and Powder Metallurgy", Vol. 29, No. 6, p. 12.

The radio wave absorbing fine particles used in the method of the present invention have a particle size of about 0.05 to 10 μm, and the particles are preferably contained in the radio wave absorbing powder resin composition in an amount of about 50 to 95% by weight. .

In the above range, if the amount of radio wave absorbing fine particles is less than 50% by weight, the magnetic wave absorption effect in the high frequency region 1 cannot be expected to be very good, and conversely, if it exceeds 95% by weight, it will be difficult to obtain a uniform coating. I don't really like it either.

The radio wave absorbing powder resin composition of the present invention includes a composition in which all of the radio wave absorbing fine powder is encapsulated in each individual resin powder, a resin powder containing most of the radio wave absorbing fine powder, It means a mixture of a small amount of radio wave absorbing fine powder (provided that the total amount of radio wave absorbing fine powder falls within the above range).

In addition to the above-mentioned components, components generally used in powder coatings, such as anti-sag agents, curing accelerators, antioxidants, extender pigments, etc., may be added to the radio wave-absorbing powdered resin composition as necessary. You can also do that.

Furthermore, the particle diameter range of the radio wave absorbing powdered resin composition is about 0.5 to 100 μm, preferably about 1 to 50 μm.

On the other hand, there are no particular restrictions on the molding methods to which the method of the present invention can be applied, and commonly used molding methods such as compression molding, transfer molding, lamination molding, and injection molding (reaction and liquid injection molding methods are also applicable). ), blow molding method, vacuum molding method, etc.

In addition, the plastic materials used in these molding methods include unsaturated polyester resin, phenolic resin,
Commonly used for molding such as epoxy resins, urea and melamine resins, styrene resins, acrylic resins, vinyl resins, polyethylene resins, silicone resins, ABS resins, nylon resins, polyacetal resins, polycarbonate resins, polyphenylene oxide resins, polypropylene resins, etc. thermosetting or thermoplastic resins, and these resins are kneaded with reinforcing fibers, fillers, curing agents, stabilizers, colorants, thickeners, mold release agents, foaming agents, flame retardants, etc. Resin composition, further sheet molding compound (SM
C), bulk molding compound (B M
C) etc. can be used.

Next, the molding method of the present invention will be explained.

In the method of the present invention, either the conductive powdered resin composition or the radio wave absorbing powdered resin composition is electrostatically coated into a mold, and then the powdered resin composition is coated thereon. The other powdered resin composition of the resin compositions is electrostatically applied.

In other words, (1) when a radio wave absorbing powdered resin composition is applied as the first layer, a conductive powdered resin composition is applied as the second layer, and (2) a conductive powdered resin composition is applied as the first layer. When a radio wave absorbing powdered resin composition is applied, the radio wave absorbing powdered resin composition is applied as a second layer.

It is a matter of course that a composite layer of two or more layers can be obtained, and in that case, it is sufficient to apply a different type of powdered resin composition from the previously applied powdered resin composition.

Furthermore, a colored or transparent powdered resin composition containing or not containing a colored bait is applied as a powdered resin composition applied on the second layer to exhibit an aesthetic or protective function. is also possible.

As a typical example of the present invention, the method for the case (1) will be described in detail below.

First, the electromagnetic wave-absorbing powder resin composition obtained as described above is charged to -60 to -90 KV using an electrostatic powder coating machine, etc., and applied to the inside of the mold.The thickness of the coating film is determined as necessary. Although it is determined, it is usually about 10 to 200 μm.

Then, the conductive powder resin composition is electrostatically applied thereon at -30 KV to -90 KV in the same manner as described above. The film thickness is preferably about 10 to 200 μm.

Finally, plastic materials are filled into the molds and molded at predetermined temperatures and/or pressures.

In this way, each powdered resin composition in the mold is anchored and adhered to the molded plastic surface by the heat of the plastic material and/or the heat of molding, etc., and a plastic molded body having a uniform radio wave absorbing and conductive coating on the surface is formed. can get.

The method (1) of the present invention will be explained with reference to drawings regarding a typical injection molding method. FIG. 1 is a schematic diagram showing the method of the present invention, and FIG. 2 is a dotted line portion of step E in FIG. 1. FIG. 3 is an enlarged view of the main part of the obtained plastic molded body.

As shown in FIG. 1, in the pre-process A, the fixed mold 3 (
10) Fix the masking material 5 on unnecessary parts.

In the coating step B, the radio wave absorbing powdered resin composition 2a is applied to the surface of the fixed mold 3 (10) by electrostatic coating a6. Next, in the coating process, an electrostatic coating machine 6”
The conductive powdered resin composition 4a is applied onto the radio wave absorbing powdered resin composition coating 2a.

Finally, remove the masking material and perform the heating step E if necessary.
to plasticize the applied powdered resin compositions 2a and 4a.

Next, in the molding process F, a movable mold 3 is placed on the fixed mold 3a.
b is placed and the mold is closed, and the gap in the mold is filled with molten plastic material through the filling hole 3b'' and molded, and at the same time, the conductive coating 4 and the radio wave absorbing coating 2 are anchored and adhered to the surface of the plastic molded body 1.

In the demolding process G, a plastic plate having a coating 2 with a conductive function and a coating 4 with a radio wave absorbing function on the surface is used.
Open the mold and take out the molded weight.

In this way, a plastic molded article having a conductive coating and a radio wave absorbing coating of uniform thickness can be efficiently obtained.

In addition, in the molding method of the present invention, the mold may be preheated in advance, or in the case of a mold at room temperature or a mold with a low preheating temperature, it may be heated with hot air, electricity, infrared rays, etc. after applying the powdered resin composition. preferable.

By doing so, it is possible to prevent scattering of the powdered resin composition adhered only by electrostatic force by electrostatic coating.

Note that the preheating of the mold refers to a case where the mold temperature is higher than room temperature due to heat applied from the outside or heat generated during molding of a plastic material.

In addition, (2) heating after applying the powdered resin composition refers to heating after applying the radio wave absorbing powdered resin composition and/or heating after applying the conductive powdered resin composition, and refers to heating after applying the electroconductive powdered resin composition. It is preferable that the powder particles are partially softened and melted to such an extent that the powder particles adhere to each other.

In the method of the present invention, the mold preheating temperature and the powder It is particularly preferable that the softening point and melting point of the resin in the resin composition are within the range of (melting point + 10° C.)≧mold preheating temperature≧softening point.

If the mold preheating temperature is lower than the softening point of the resin, the adhesion between the mold and the powdered resin composition will be low, leading to the movement of the plastic material due to the pressure applied to the plastic material during molding and the injection speed during injection. The powdered resin composition moves or scatters due to pressure and the like, making it difficult to obtain a uniform coating. Also, the mold preheating temperature is (melting point of resin + lO℃)
If the temperature exceeds the
It becomes fluid and moves due to the movement of the plastic material, injection speed, pressure, etc. as described above, making it difficult to obtain a uniform coating. Particularly, in the injection molding method, undesirable problems may occur, such as a striped coating or a molded product having no coating at all, especially near the injection port (nozzle).

(Effects of the Invention) As described above, the method of the present invention causes safety and hygiene problems due to organic solvent volatilization, scattering of powder paint, adhesion to the outside of the mold, uneven film thickness, etc. The problem has been solved and a powdered resin composition containing a high concentration of conductive fine powder can be efficiently produced.
It can be uniformly adhered to the plastic surface, and can absorb electromagnetic waves in the high frequency range.Furthermore, when a radio wave absorbing layer is provided as the outermost layer, there are no electric shocks or leakage accidents that would occur if only a conductive film was used. can also be prevented.

Hereinafter, the present invention will be explained in detail with reference to Examples.

"Parts" or "%" are expressed as "parts by weight" or "% by weight." Prior to Examples, each powdered resin composition was manufactured using the formulations shown below.

'He's Lj' [Formulation 1] Epoxy resin 45% Dicyandiamide 4% Mn-Zn ferrite particles (average particle size approximately 1-2 μm) 50% Flow aid 1% The epoxy resin is manufactured by Shell Chemical ■, trade name: Epicoat # 1004 (epoxy equivalent 875-975, melting point 98°C, softening point 70°C),
As the flow aid, Modaflow (trade name, manufactured by Monsanto) was used.

The composition of Formulation 1 was mixed and kneaded at 110°C or lower using a heated roller, the kneaded mixture was cooled and pulverized by a pulverizer, and the portion that passed through a 100-mesh sieve was mixed into a radio wave-absorbing powder. It was created as a resin composition (A″″1).

[Formulation 2] Epoxy resin 10% Methyl ethyl ketone 50% Ni-Zn ferrite particles (average particle size approximately 0.5 to 1 μm) 40% The epoxy resin is manufactured by Shell Kagaku ■, trade name Epicote #100
A mixture of 2 (epoxy weight 1600-700, melting point 83°C, softening point 57°C) and 91004 in a ratio of l=1 (melting point 92°C, softening point 65°C) was used.

The composition consisting of Formulation 2 was dispersed for 2 hours using a magnetic bot mill to obtain a liquid composition. Next, the liquid composition was sprayed into 3000 parts of water with a water temperature of 20° C. or less under high speed stirring to emulsify the liquid composition and extract the solvent into the water to form resin particles.

After that, filtration and water washing were repeated until the average particle size was approximately 100.
Resin particles of μm were obtained. After adjusting the water content to around 50%, dispersion was performed using a ball mill to pulverize the resin particles to obtain a slurry-like powdered resin composition. Furthermore, after repeating water washing three or more times, it is filtered, dried under dry air at 20°C or less, crushed, and sieved (100 meshes) to create a radio wave absorbing powdered resin composition (A-2). did.

[Blend 3] Polyester resin 10% Mn-Zn
ferrite particles (average particle diameter of about 1 to 2 μm) 50% methyl ethyl ketone 40% The polyester resin is manufactured by Nippon Yubika under the trade name GV-110 (melting point 85°C,
(softening point: 65°C) was used.

A radio wave absorbing powdered resin composition (A-3) was prepared by using the composition of Formulation 3 in the same manner as Formulation 2.

[Formulation 4] Acrylic resin 9% Nf-Z
N-type ferrite particles (average particle size approximately 0.5 to 1 μm) 51% Methyl ethyl ketone 40% The acrylic resin used was A-2243 (melting point 114°C, softening point 70°C) manufactured by Dainippon Ink & Chemicals. .

A radio wave absorbing powdered resin composition (A-4) was prepared by using the composition of Formulation 4 in the same manner as Formulation 2.

・ ・4 Hi's 'Composition C Formulation 5] Epoxy resin 12% dendrite-shaped copper powder 48% flow aid (same as formulation 1) 1% methyl ethyl ketone
The 39% epoxy resin is Epicoat #1002 manufactured by Shell Chemical Co., Ltd., and the dendrite-shaped copper powder is electrolytic copper powder MD-1 (trade name) manufactured by Mitsui Mining & Mining Co., Ltd. (325 mesh (opening 44 μm), which passes 80% or more. used each.

The composition consisting of the above formulation was dispersed in a magnetic bot mill for 2 hours to obtain a liquid composition.

Then, the liquid composition was heated to a water temperature of 20°C under high speed stirring.
The following liquid composition was sprayed into 3000 parts of water to emulsify the liquid composition and extract the solvent into the water to form resin particles. Thereafter, filtration and water washing were repeated to obtain resin particles with an average particle diameter of about 100 μm. After adjusting the water content to around 50%, the resin particles were further finely pulverized to obtain a slurry-like powdered resin composition. After repeating water washing three or more times, it is filtered and dried under dry air at a temperature of 20°C or less.
Grind and sieve (15o mesh) to obtain conductive powder/resin
80/20 (weight ratio) conductive powder resin composition (B
-1) was created.

[Formulation 6] Epoxy resin 9% dendrite-shaped copper powder 51% flow aid (same as formulation 1) 1% methyl ethyl ketone
The 39% epoxy resin is manufactured by Shell Chemical Co., Ltd. under the trade name Epikote #1001 (epoxy equivalent: 450-500. Melting point: 69°C, softening point: 50°C). The dendrite-shaped copper powder is manufactured by Mitsui Mining & Co., Ltd., electrolytic copper powder under the trade name MD-. I and MF
A mixture of Dt (weight average particle diameter 8 μm) in a ratio of 1:1 by weight was used in each case.

A liquid composition was prepared in the same manner as in Formulation 5, and then a conductive powdery resin composition (B-2) having a conductive fine powder/resin ratio of 85/15 (weight ratio) was prepared in the same manner.

[Formulation 7] Epoxy resin 6% dendrite-shaped copper powder 54% flow aid (same as formulation 1) 1% methyl ethyl ketone
The 39% epoxy resin is manufactured by Ciba Geigy and has the trade name Araldite 6097 (epoxy equivalent: 900-100
0, melting point 100℃, softening point 80℃), dendrite-shaped copper powder is Mitsui Mining & Mining Side Electrolysis fI Powder trade name MF
Di was used respectively.

The composition having the above formulation was dispersed in a paint shaker for 1 hour to obtain a liquid composition.

Next, after creating a conductive powdered resin composition in the same manner as Formulation 5, as a curing agent, an imidazole-based epoxy resin curing agent [the above-mentioned Curazole CIIZ] was dry-mixed as a fine powder at a ratio of 4 phr, Conductive powder composition (B-
3) was created.

[Blend 8] Epoxy resin 12% Nickel powder 48% Methyl ethyl ketone
The 40% epoxy resins are manufactured by Shell Chemical and have the trade names Epicote #1002, #1004, and #10.
07 (epoxy equivalent 1750-2200, melting point 128℃
, softening point: 85°C) in a ratio of 1:1:1 (weight ratio) (melting point: approximately 107°C, softening point: 65°C). (approximately 3-7 μm) and 9255 (average particle size approximately 2-3 μm)
A mixture of 1:1 (quantity ratio) was used.

The composition consisting of the above formulation was dispersed in the same manner as Formulation 5 to create a liquid composition.

Next, a conductive powder resin composition (B-4) having a conductive fine powder/resin ratio of 80/20 (weight ratio) was prepared from the above liquid composition in the same manner as in Formulation 5.

[Formulation 9] Epoxy resin 9% Nickel powder (same as Formulation 8) 51% Methyl ethyl ketone 40% Epoxy resin is manufactured by Shell Chemical ■Product name Epicote #1002, #1004, #1007,
and #1009 (epoxy equivalent 2400-3300,
melting point approximately 148°C, softening point 90°C) in 1:1:2:2, respectively.
(weight ratio) (melting point: about 135°C, softening point: 75°C) was used.

A conductive powdery resin composition (B-5) having a conductive fine powder/resin ratio of 85/15 (weight ratio) was prepared using the composition consisting of the above formulation in the same manner as in Formulation 5.

[Formulation 10] Epoxy resin 11% silver powder
48% methyl ethyl ketone
40% dicyandiamide
1% epoxy resin is Epicoat #1007,
As the silver powder, conductive silver powder (average particle diameter of about 1 μm) manufactured by Fukuda Metal Foil and Powder Industry ■ was used.

A liquid composition was prepared using the composition described above in the same manner as in Formulation 5, and then diluted by adding 50 parts of methyl ethyl ketone to 100 parts of the composition, followed by spray drying (air flow rate: 20 d). conductive fine powder/resin = 80/20 (
A conductive powdery resin composition (B-6) was prepared (weight ratio).

[Formulation 11] Polyester resin (same as formulation 3) 12% Dendrite-shaped copper powder 48% (same as formulation 5) Methyl ethyl ketone 40% The composition consisting of the above formulation was dispersed in a magnetic bore mill for one and a half hours to form a liquid composition. A conductive powder resin composition (B-7) having a conductive fine powder/resin ratio of 80/20 (weight ratio) was prepared from the liquid composition in the same manner as in Formulation 5.

[Blend 12] Acrylic resin (same as Blend 4) 9% Nickel powder (same as Blend 8) 51% Methyl ethyl ketone 40% A composition consisting of the above blend was prepared in the same manner as Blend 5, conductive fine powder/resin = 85/ 15
(weight ratio) A conductive powdery resin composition (B-8) was prepared.

Example 1 After masking the unpainted part in a fixed mold that had been preheated to 80°C, a radio wave absorbing powdered resin composition (A-'1) was electrostatically applied under a voltage of -80 KV to form a coating film. formed.

Then, in order to finally measure the surface resistance value of the conductive coating, a portion of the masking corresponding to both ends of the molded article was removed.

Thereafter, the conductive powder resin composition (B-1) was heated to -40K.
After electrostatic coating was performed under a voltage of V to form a coating film, the remaining masking was removed and the stationary mold and movable mold were sealed.

Then, a heat-resistant polystyrene resin liquid with a resin temperature of 270° C. was injection molded at an injection pressure of about 900 kg/cal.

In this way, a heat-resistant polystyrene molded body was obtained which had a uniform and highly conductive coating having a thickness of 40 μm and a surface resistance value of 0.81 ohm/portion, and a radio wave absorbing coating of 60 μm thereon.

Example 2 The non-painted part in a fixed mold preheated to 70°C was masked, and the radio wave absorbing powdered resin composition (A-2) was heated to -70°C.
After electrostatic coating was performed under a voltage of KV to form a coating film, a part of the masking was removed in the same manner as in Example 1.

Then, the conductive powder resin composition (B-2) was heated to -40K.
After static painting was performed under a voltage of V to form a coating film, the remaining masking was removed. .

After that, the movable mold and movable mold are sealed, and the resin temperature is 180℃.
of vinyl chloride resin liquid at an injection pressure of approximately 750 kg/
When injection molded with C4, it was found to be a vinyl chloride resin molded product with a uniform and highly conductive coating with a thickness of 60 μm and a surface resistance value of 0.55 ohm/mouth, and a radio wave absorbing coating with a thickness of 40 μm on top of it. I got a body.

Example 3 The non-painted part in a mold preheated to 90°C was masked, and then the radio wave absorbing powdered resin composition (A-1)
was applied to the painted area in the mold using an electrostatic coating device under a voltage of -65 KV to form a coating film, and then a part of the masking was removed in the same manner as in Example 1.

Then, the conductive powder resin composition (B-3) was heated to -40K.
Static under a voltage of V! After painting and forming a coating film,
The remaining masking was removed. Thereafter, the hard vinyl chloride sheet was heated to 125°C using a heating heater to soften it, and was fixed to the above-mentioned mold using a clamp frame, and then the air inside the mold was pumped to a vacuum level of 720 mm using a vacuum pump.
When the sheet was sucked out with Hg pressure and molded by adhering it to the mold surface, a uniform and highly conductive film with a film thickness of 60 μm and a surface resistance value of 0.47 ohm/mouth was formed, and on top of that was a film with a film thickness of 40 μm and radio waves. A hard vinyl chloride resin molded article having an absorbent coating was obtained.

Example 4 The non-painted part in the fixed mold that was preheated to 70°C was masked, and the conductive powdered resin composition (B-4) was heated to -60K.
After applying electrostatic coating under a voltage of V to form a coating film, electrostatically coating the radio wave absorbing powdered resin composition (A-2) under a voltage of -40 KV to form a coating film. , the masking was removed.

After that, the fixed mold and the movable mold are sealed, and the resin temperature is set to 220.
Injection pressure of polyethylene resin liquid at ℃ approximately 1100 kg/a
When injection molded with J, a polyethylene resin molded product was obtained, which had a uniform, highly conductive coating with a thickness of 6 µm and a surface resistance value of 1.0 ohm/mouth on a radio wave absorbing coating with a thickness of 4 µm. Obtained.

Example 5 Masking the non-painted part in the fixed mold at a temperature of 80°C,
After electrostatically applying the radio wave absorbing powdered resin composition (A-1) under a voltage of -70 KV, a portion of the masking was removed in the same manner as in Example 1.

Then, the conductive powdered resin composition (B-5) was heated to -40K.
After electrostatic coating was performed under a voltage of V to form a coating film, the remaining masking was removed and the mold was heated to 95° C. with an infrared heater to form a coating film. After that, the fixed mold and the movable mold were sealed, and ABS resin liquid with a resin temperature of 230°C was injection molded at an injection pressure of about 1000 kg/cat to obtain a film thickness of 60 μm and a surface resistance value of 0.60 ohm. An ABS resin molded body having a uniform and highly conductive coating with a diameter of 1.2 mm and a radio wave absorbing coating with a thickness of 5 μm thereon was obtained.

Example 6 The unpainted part of the inner surface of the mold, which had been preheated to 87°C, was masked and the radio wave absorbing powdered resin composition (A-4) was prepared.
After coating the inner surface of the mold under a voltage of -60 KV using an electrostatic powder coating device, a part of the masking was removed in the same manner as in Example 1.

Then, the conductive powdered resin composition (B-4) was heated to -30K.
After electrostatic painting under a voltage of V, the remaining masking was removed, the inner surface of the mold was heated with an infrared heater, and the mold was heated to 100℃.
I made it.

Thereafter, polypropylene extruded into a tube at 195°C was inserted into the mold, and 3.5 kg was placed inside the tube.
/cd of compressed air was blown into the polypropylene to make it expand, and when the polypropylene was tightly attached to the inner surface of the mold and molded, the film thickness was 60 μm.
A polypropylene resin molded article was obtained which had a uniform, highly conductive coating with a surface resistance value of 0.10 ohm/mouth and a radio wave absorbing coating with a thickness of 5 μm thereon.

Example 7 The non-coated parts in a mold preheated to 70°C were masked, and the i-electric powder resin composition (B-6) was coated with an electrostatic powder coating device under a voltage of -70 KV. After coating the painted part in the mold to form a coating film, electrostatically coating the radio wave absorbing powdered resin composition (A-1) under a voltage of -40 KV to form a coating film, I removed the masking.

After that, phenol resin powder preheated to 116°C was put into the mold, the inside of the mold was closed, and the mixture was heated to 155°C and heated to 180°C.
When the mold was compressed and molded with a pressure of 1 kg/-, a uniform, highly conductive film with a thickness of 60 μm and a surface resistance of 0.15 ohm/hole was formed on the radio wave absorbing film with a thickness of 50 μm. A phenolic resin molded article having the following properties was obtained.

Example 8 The inner coated part of the mold, which had been preheated to 750°C, was masked, and the radio wave absorbing powdered resin composition (A-2) was heated to -70°C.
After electrostatic coating was performed under a voltage of KV to form a coating film, a part of the masking was removed in the same manner as in Example 1.

Then, the conductive powdered resin composition (B-7) was heated to -40K.
After electrostatic painting under a voltage of V to form a coating, the remaining
Removed the masking. After that, the fixed mold and the movable mold were sealed, and a polycarbonate resin liquid with a resin temperature of 260'c was injection molded at an injection pressure of 1500 kg/d to obtain a film thickness of 4011 m and a surface resistance value of 1.1 ohm/d. A polycarbonate resin molded body having a uniform and highly conductive film at the mouth and a radio wave absorbing film having a thickness of W-50 μm thereon was obtained.

Example 9 The inner coated part of the mold, which had been preheated to 85°C, was masked, and the radio wave absorbing powdered resin composition (A-1> was mixed with -6
After electrostatically painting under a voltage of 0KV to form a coating film,
As in Example 1, part of the masking was removed.

Then, the conductive powdered resin composition (B-8) was heated to -40K.
After electrostatic painting under a voltage of V, the remaining masking was removed. After that, the fixed mold and the movable mold are sealed, and the resin temperature is set to 3.
30t' of PPO (polyphenylene oxide) resin was injection molded at an injection pressure of 1500kg/-, with an average film thickness of 50.
P with a highly conductive film with a surface resistance value of 0.95 ohm/mouth and a radio wave absorbing film with a thickness of 40 μm on top of it.
A PO resin molded body was obtained.

Example 10 The unpainted part of the inner surface of the mold, which had been preheated to 80°C, was masked, and the radio wave absorbing powdered resin composition (A-3) was prepared.
After coating the painted portion of the mold using an electrostatic powder coating device, a portion of the masking was removed in the same manner as in Example 1.

Then, the conductive powdered resin composition (B-7) was heated to -40K.
After electrostatic painting under a voltage of V, the remaining masking was removed.

Thereafter, the polyethylene resin extruded into a tube shape at 175°C was inserted into the mold, and 3.2 kg/d of compressed air was blown into the tube to inflate it and bring it into close contact with the inner surface of the mold.
When molded, a uniform, highly conductive film with a film thickness of 60 μm and a surface resistance value of 0.67 ohms/hole was formed, and a film with a film thickness of 40.
A polyethylene resin molded body having a radio wave absorbing coating of un was obtained.

Example 11 The inner coated part of the mold, which had been preheated to 105°C, was masked, and the electromagnetic wave absorbing powdered resin composition (A-4) was applied to -
After electrostatically painting with a voltage of 80KV to form a coating film,
A portion of the masking was removed in the same manner as in Example 1 above.

Then, the conductive powdered resin composition (B-8) was heated to -40K.
After electrostatic painting under a voltage of V, the remaining masking was removed.

After that, the fixed mold and the movable mold are sealed, and the resin temperature is set to 240.
Injection pressure of polypropylene resin liquid at ℃ 1500kg/c
Injection molded at d, film thickness 60. crm, surface resistance value 0.
A polypropylene resin molded article was obtained which had a uniform, highly conductive coating of 51 ohm/mouth and a radio wave absorbing coating with a thickness of 40 μm thereon.

[Brief explanation of the drawing]

FIGS. 1A to 1G are process schematic diagrams showing an injection molding method which is an example of the method of the present invention. Figure 2 is an enlarged view of the dotted line in process E in Figure 1.
The figure is an enlarged sectional view of a plastic molded article obtained by the method of the present invention. DESCRIPTION OF SYMBOLS 1... Plastic molded object, 2... Radio wave absorbing coating, 3... Molding die, 4... Conductive coating, 5... Masking material, 6... Electrostatic coating machine. Showa year, month, day 1, case description 1985 patent application No. 62726 2
, Title of the invention Plastic molding method 3, Relationship with the case of the person making the amendment Applicant name (332) Dainippon Toyo Co., Ltd. Kasei Kogyo Co., Ltd. 4, Agent, Subject of amendment Detailed explanation of the invention in the specification In column ■, the following parts of the description should be corrected as follows.

Claims (11)

[Claims] (1) In the plastic molding method, first, a powdered resin composition, either a conductive powdered resin composition or a radio wave absorbing powdered resin composition, is applied into a mold by electrostatic coating, and then the After applying the other powdered resin composition of the powdered resin compositions on top by electrostatic coating, a plastic material is filled and molded, and the powdered resin composition is heated by the heat of the filling material and/or the heat during molding. A plastic molding method for forming a multilayer coating on the surface of a plastic molded article, which method comprises plasticizing and compressing the molded plastic to bring a thermosetting or thermoplastic resin coating into close contact with the surface of the molded plastic. (2) The conductive powder resin composition contains 70% conductive fine powder.
The plastic molding method according to claim 1, which is a thermoplastic or thermosetting powdery resin composition containing in a range of 95% by weight. (3) The radio wave absorbing powder resin composition is a thermoplastic or thermosetting powder resin composition containing radio wave absorbing fine powder in a range of 50 to 95% by weight.
Plastic molding method described in section. (4) The plastic molding method according to claim (1), wherein the plastic molding method is an injection molding method, a blow molding method, a transfer molding method, or a vacuum molding method. (5) The plastic molding method according to claim (1), wherein the mold is a preheated mold. (6) The plastic molding method according to claim (1), wherein the conductive and/or radio wave absorbing powdered resin composition is fused or hardened by heating before being filled with the plastic material. (7) The melting point and softening point of each resin component used in the conductive and radio wave absorbing powdered resin composition and the mold preheating temperature are:
The plastic molding method according to claim (5), wherein (melting point +10°C)≧mold preheating temperature≧softening point. (8) The plastic molding method according to claim (1) or (2), wherein the conductive powder is a fine metal powder having a dendrite shape. (9) The plastic molding method according to claim (1) or (3), wherein the radio wave absorbing powder is spinel type ferrite powder. (10) The conductive powdered resin composition is obtained by dispersing, granulating, and solvent extracting a liquid composition consisting of a water-soluble solvent, a water-insoluble and water-insoluble resin, and a conductive fine powder, and then separating the composition. The plastic molding method according to claim 1, which is a powdered resin composition obtained by a wet granulation method in which the resin composition is dried. (11) The radio wave-absorbing powdered resin composition is prepared by dispersing, granulating, and solvent-extracting a liquid composition consisting of a water-soluble solvent, the water-insoluble and solvent-soluble resin, and radio wave-absorbing fine powder in water. The plastic molding method according to claim (1), which is a powdered resin composition obtained by a wet granulation method in which the resin composition is separated and dried.