JPH0358573B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a plastic molding method in which a multilayer coating consisting of a conductive coating and a protective and/or aesthetic coating formed on the conductive coating is formed on the surface of a plastic molded article. Regarding the method. More specifically, the present invention relates to a method for obtaining a plastic molded body for purposes such as shielding electromagnetic waves, preventing static electricity, and providing aesthetics.

(Prior art) In recent years, it has become clear that electromagnetic waves and static electricity are the cause of malfunctions in electronic devices that use semiconductor devices, and in Western countries, malfunctions are caused by electromagnetic waves and static electricity.
Regulations for electronic devices with built-in IC and LSI elements are beginning to be enacted into law, and the electronic device industry is urged to take countermeasures.

Currently, one of the methods for shielding these sources of interference electromagnetic waves is to knead electrostatic powder into plastic and then mold it to give the molded plastic body itself a conductive function (for example, Japanese Patent Publication No. 35-9643 No.) is known. however,
Although this method has the advantage of being easy to work with, it requires the inclusion of a large amount of conductive fine 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. , problems in molding, and other various drawbacks, so it is not put into practical use much.

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 organic solvents contained in the conductive paint, as well as undercoat measures to improve the adhesion strength of the paint film and prevent paint peeling. There were problems such as difficulty in obtaining

Recently, a method has been developed in which a solvent-soluble conductive paint is applied with a brush or a spray gun into a mold for electronic device housings, and then the plastic is molded within the mold to integrate the plastic molded body and the conductive coating. has also been proposed (for example, Special Publication No. 48-25061).
According to this method, a grease-like composition is applied inside a mold, a conductive powder such as graphite is sprayed onto it, and then a liquid synthetic resin is injected and hardened to make 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 problems with the work, 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 example 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, powder coatings containing a small amount of ordinary color pigments are heated and applied to the inner surface of a pressure molding mold in a fluidized bed or by spraying, and then compression molded using SMC or BMC.
A method of forming a protective or colored film on the FRP surface is known (for example, Japanese Patent Publication No. 58-44459,
JP-A-57-181823, JP-A-58-124610).

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

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. Furthermore, if the outside of the housing is painted, the colors of the conductive fine powder are limited, so there is a big problem in terms of aesthetics, and furthermore, it is necessary to protect the conductive coating from being easily scratched. Various problems arose, including the necessity of the project.

(Problems to be Solved by the Invention) The present invention solves problems such as scattering of powder paint, adhesion to the outside of the mold, and uneven film thickness, and the present invention solves problems such as powder paint scattering, adhesion to the outside of the mold, and uneven film thickness. Adheres powdered resin composition efficiently and uniformly to plastic surfaces,
The object of the present invention is to provide a method for molding a plastic molded article having electrical conductivity and a surface resistance value of about 10 ² ohms/□ or less.

Furthermore, it is an object of the present invention to provide a plastic molding method for forming a film having protective and/or aesthetic functions for the conductive film.

(Means for Solving the Problems) That is, the present invention applies a powdered resin composition containing a high concentration of conductive fine powder into a mold by electrostatic coating, and then molds the plastic. This invention relates to a plastic molding method in which a conductive film is brought into close contact with the surface of a plastic molded body by anchoring, and then a conventional paint is applied thereon for finishing.

(Specific Description of the Invention) The powdered resin composition used in the method of the present invention contains 70 to 95% by weight of conductive fine powder, preferably 75% by weight.
It is a thermosetting or thermoplastic resin composition containing a high concentration of ~90% by weight.

The conductive fine powder refers to metal powder or alloy powder such as gold, platinum, palladium, silver, copper, or nickel; or inorganic powder or plastic powder that is an electrically poor conductor such as nickel-coated mica powder. Coated with a metal with good conductivity; crystalline carbon such as graphite carbon;
A fine powder with good electrical conductivity, such as amorphous carbon powder such as acetylene black or ketschen black, with a particle size range of 0.5 to 100 μm, preferably 1 to 100 μm.
It is about 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 contained in the powdered resin composition at a concentration of 70%.
It is contained in the range of ~95% by weight.

In the present invention, the powdered resin composition containing conductive fine powder includes a composition in which conductive fine powder is encapsulated in each individual resin powder, and a resin powder in which most of the conductive fine powder is encapsulated. A mixture of a small amount of conductive fine powder, provided that the total amount of conductive fine powder 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 powdered resin composition is less than 70% by weight, it will not be possible to form a good conductive film on the surface of the plastic molded product, while if it exceeds 95% by weight, Both are unfavorable because they make it difficult to perform electrostatic coating efficiently.

As the resin used as a color vehicle in the powdered resin composition of the present invention, any thermosetting or thermoplastic resin commonly used for powder coatings, powder molding, etc. can be used.

Examples of the thermosetting resin include acrylic resin, polyester resin, epoxy resin, alkyd resin,
Urethane resin, epoxy modified polyester resin,
An example is acrylic modified polyester resin. In particular, acrylic resins, polyester resins, and epoxy resins are preferred from the viewpoint of storage stability and coating film adhesion.

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

Examples of the curing agent for the thermosetting resin include dicyandiamide, acid anhydride, imidazole derivative, aromatic diamine, boron trifluoride amine complex compound, hydrazide, decamethylene dicarboxylic acid, blocked isocyanate compound, amino resin, etc.
Those normally used for thermosetting powder coatings, powder molding, etc. can be used.

Further, as the thermoplastic resin, known ones such as acrylic resin, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, styrene polymer, vinyl chloride polymer, polyamide resin, butyral resin, cellulose resin, and petroleum resin are used. Can be mentioned.

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 addition to the above-mentioned components, the powdered resin composition may contain an anti-sag agent, a curing accelerator, an antioxidant,
It is also possible to add and mix components such as pigments that are generally used in powder coatings.

The conductive powdery resin composition used in the method of the present invention can be obtained by a known method for producing powder coatings and the like.

For example, after heating and melting and mixing the resin and conductive powder, and other necessary hardening agents, additives, etc.,
After using a mechanical pulverization method of cooling, pulverizing, and sieving, or dispersing the resin, conductive fine powder, and other necessary hardening agents, additives, etc. in a solvent, the obtained dispersion is immersed in heated air. Dry spray method etc. can be applied.

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, water-soluble solvents such as alcohols, ethylene glycol derivatives, diethylene glycol derivatives, esters, and ketones (preferably 20
A liquid composition obtained by dissolving the resin in a solution with a solubility in water of 10 to 30% by weight at °C, and then mixing the resin, conductive fine powder, and other necessary curing agents, additives, etc. A substance (hereinafter referred to as a dispersion) is emulsified and dispersed in an amount of water (approximately 3 to 40 times the amount of the dispersion) in which all the water-soluble solvents contained in the dispersion are dissolved. 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 stirring or mixing with a line mixer is
This process is continued until the solvent in the emulsified fine particles migrates into the 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, the particles are adjusted using a ball mill, pot mill, sand mill, etc., and then dried to prevent the resin particles from agglomerating, preferably by freeze drying, vacuum drying, etc., and if necessary, sieved to obtain the conductive powder of the present invention. A resin composition is obtained. Such a manufacturing method is 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, 56-5796, 56
It is detailed in the -29890 publication.

In this way, it is possible to obtain a powdered resin composition containing a high concentration of conductive fine powder and having a relatively nearly spherical shape while maintaining the shape of the powder.

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 160°C.
180℃, preferably softening point 60~130℃, melting point 70~
The temperature is about 160℃.

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

Furthermore, 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 it is about 1 to 50 μm.

On the other hand, there are no particular restrictions on the molding method 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) (including yon molding method), blow molding method, vacuum molding method, etc.

Plastic materials used in these molding methods include unsaturated polyester resins, phenolic resins, epoxy resins, urea and melamine resins, styrene resins, acrylic resins, vinyl resins, polyethylene resins, silicone resins, and ABS.
Thermosetting or thermoplastic resins commonly used for molding, such as resins, nylon resins, polyacetal resins, polycarbonate resins, polyphenylene oxide resins, polypropylene resins, etc., and reinforcing fibers, fillers, Resin compositions kneaded with curing agents, stabilizers, colorants, thickeners, mold release agents, foaming agents, flame retardants, etc., as well as sheet molding compounds (SMC), bulk molding compounds (BMC), etc. Available for use.

Further, the paint used in the method of the present invention is a conventional paint composition such as a solvent-based paint, a solvent-free paint, a water-soluble or water-dispersible paint, etc., which is liquid at room temperature.

The resin as a color vehicle used in the coating composition is a common liquid resin such as alkyd resin, acrylic resin, vinyl resin, epoxy resin, urethane resin, polyester resin, fluororesin, cellulose resin, melamine resin, etc. Anything used for paint can be used.

In addition, a curing agent such as a polyisocyanate or an amino compound used in combination with the above color vehicle may be used in combination, and if necessary, extender pigments, coloring pigments, dyes, various additives, solvents, etc. may be appropriately combined. It is also possible to use

The coating composition is preferably a coating that dries at room temperature, but accelerated heating or heat-curing coating compositions, and ultraviolet or radiation-curable compositions may also be used in some cases.

Furthermore, in the method of the present invention, the coating composition contains 1 to 70% by weight of a conductive powder as shown below.
By using a composition containing a certain amount, it is possible to form an antistatic coating on the surface.

The conductive fine powder includes conductive metal oxides such as conductive zinc oxide, tin oxide, antimony oxide, and indium oxide; mixtures and/or solid solutions containing at least one of the above oxides; colored pigments; A mixture with the conductive oxide; a compound such as a colored pigment whose surface is coated with the conductive oxide; or a crystalline carbon such as graphite carbon, or amorphous carbon powder such as acetylene black or ketschen black. It is a fine powder with good electrical conductivity, such as conductive carbon, and has an average particle diameter of 100 μm or less, preferably about 0.05 to 50 μm. These powders can be used alone or in combination of two or more.

In the method of the present invention, the conductive fine powder is
It is contained in the liquid coating composition in an amount of 1 to 70% by weight.

In particular, in the present invention, when conductive carbon is used as conductive fine powder, the content is 1 to 1.
The content is preferably in the range of 50% by weight, and when other conductive fine powder is used, the content is preferably in the range of 20 to 70% by weight.

In this way, an antistatic coating having a surface resistance value of more than 10 ³ ohms/□ and less than 10 ¹¹ ohms/□ can be obtained.

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

The conductive fine powder obtained as described above was heated to 70 to 95
The powdered resin composition containing % by weight is charged to -60 to -90 KV using an electrostatic powder coater or the like and applied to the inside of the mold. The thickness of the coating film is determined depending on necessity, but is usually about 10 to 200 μm.

Next, fill the mold with plastic material,
Each is molded at a predetermined temperature and/or pressure.
In this way, the powdered resin composition in the mold is anchored and adhered to the surface of the molded plastic by the heat of the plastic material and/or the heat of molding, etc., and a molded plastic product having a uniform conductive coating on the surface is obtained. Then, after demolding, the coating composition is applied by a conventional method such as spraying, airless spraying, brushing, electrostatic coating, etc., and then dried to obtain the plastic molded object of the present invention.

The process up to the molding process of the method of the present invention will be explained using drawings using a typical injection molding method.
The figure is a schematic diagram during injection molding, Figure 2 is an enlarged view of the dotted line part of step D in Figure 1, and Figure 3 shows the plastic molded product finally obtained by the method of the present invention. FIG.

As shown in FIG. 1, in the pre-process A, a masking material 4 is fixed to unnecessary parts of the fixed mold 3a.

In coating step B, the electrostatic coating machine 5 coats the powdered resin composition 2a on the surface of the fixed mold 3a. Next, remove the masking material and remove if necessary.
In heating step D, the applied powdered resin composition 2a is plasticized by heating.

Next, in the molding process E, the movable mold 3b is placed on the fixed mold 3a and the mold is closed, and a filling hole 3 is formed in the gap in the mold.
A molten plastic material is filled from b' and molded, and at the same time, the conductive coating film 2 is anchored and adhered to the surface of the plastic molded body 1.

Then, when the mold is demolded, a plastic molded article having a conductive coating of uniform thickness can be efficiently obtained.

After demolding, a colored or clear paint 6 is applied onto the conductive film and dried to protect and/or give an aesthetic finish to the conductive film and obtain a plastic molded body. If necessary, the primer paint may be applied first, and then the paint may be applied.

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.

In particular, in injection molding methods, blow molding methods, vacuum forming methods, etc. in which the plastic material is injected under pressure or the plastic material moves during molding, the mold preheating temperature and the resin in the powdered resin composition are The softening point and melting point of (melting point + 10℃) ≧
Preferably, the mold preheating temperature is within the range of 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. Additionally, if the mold preheating temperature exceeds (resin melting point + 10°C), the powdered resin composition will melt after being applied and will exhibit fluidity, causing the movement of the plastic material, injection speed, pressure, etc. etc., 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).

As described above, according to the method of the present invention, problems such as scattering of powder paint, adhesion to the outside of the mold, and uneven film thickness are solved, and powder paint containing a high concentration of conductive fine powder can be used. The resin composition can be efficiently and uniformly adhered to the plastic surface, and the resulting conductive film can be protected and/or aesthetically finished.

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 the Examples, a powdered resin composition was manufactured using the formulation shown below.

[Formulation 1] Epoxy resin 12% Dendrite-shaped copper powder 48% Flow aid 1% Methyl ethyl ketone 39% The epoxy resin is manufactured by Ciel Chemical Co., Ltd. under the trade name Epicote #1002 (epoxy equivalent 600-700, melting point 83°C,
The dendrite-shaped copper powder is electrolytic copper powder manufactured by Mitsui Mining & Mining Co., Ltd., product name MD-1 [more than 80% passes through 325 mesh (opening 44 μm)].
As the flow aid, Modaflow (trade name, manufactured by Monsanto) was used.

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

Next, the liquid composition was sprayed into 3000 parts of water at a 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. 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. Furthermore, after repeating water washing three times or more, it is filtered, dried under dry air at 20℃ or less, crushed, and sieved (150 meshes) to obtain conductive fine powder/resin.
A powdered resin composition (1) of 80/20 (weight ratio) was prepared.

[Formulation 2] Epoxy resin 9% Dendrite-shaped copper powder 51% Flow aid (same as Formulation 1) 1% Methyl ethyl ketone 39% Epoxy resin is manufactured by Ciel Chemical Co., Ltd. under the trade name Epicote #1001 (epoxy equivalent 450-500, melting point 69℃, softening point 50℃), and the dendrite-shaped copper powders are electrolytic copper powders manufactured by Mitsui Mining & Mining Co., Ltd. under the trade names MD-1 and MF-D _2.
(weight average particle diameter: 8 μm) were mixed in a 1:1 ratio by weight.

After making the liquid composition in the same way as Formulation 1,
A powdered resin composition (2) having a conductive fine powder/resin ratio of 85/15 (weight ratio) was prepared in a similar manner.

[Formulation 3] Epoxy resin 6% Dendrite-shaped copper powder 54% Flow aid (same as Formulation 1) 1% Methyl ethyl ketone 39% The epoxy resin is manufactured by Ciba Geigy Corporation under the trade name Araldite 6097 (epoxy equivalent 900-1000, melting point 100°C) ,
The dendrite-shaped copper powder used was electrolytic copper powder MF-D ₂ manufactured by Mitsui Mining & Mining Co., Ltd., 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 powdered resin composition in the same manner as in Formulation 1, 4 phr of an imidazole-based epoxy resin curing agent [product name: Kyuazol C ₁₁ Z, manufactured by Shikoku Kasei Kogyo Co., Ltd.] was added as a fine powder. A powder composition (3) with a conductive fine powder/resin ratio of 90/10 (weight ratio) was prepared by dry mixing at a ratio of 90/10 (weight ratio).

[Formulation 4] Epoxy resin 15% Nickel powder 45% Flow aid (same as formulation 1) 1% Methyl ethyl ketone 39% Epoxy resins are manufactured by Ciel Chemical Co., Ltd. under the trade name Epicote #1001, #1002, and #1004 (epoxy equivalent 875
~975, melting point 98℃, softening point 70℃) each at 1:1:
1 (weight ratio) (melting point 86℃,
(softening point: 58 DEG C.), and nickel powder manufactured by Inco Co., Ltd. under the trade name #255 (average particle size: approximately 2 to 3 .mu.m).

The composition consisting of the above formulation was made into a liquid composition in exactly the same manner as Formulation 3, and the powdered resin composition (4) with conductive fine powder/resin = 75/25 (weight ratio) was prepared in the same manner as Formulation 1. It was created.

[Composition 5] Epoxy resin 12% Nickel powder 48% Methyl ethyl ketone 40% Epoxy resin is manufactured by Ciel Chemical Co., Ltd. under the trade name Epicote #1002, #1004, #1007 (epoxy equivalent: 1750~
2200 (melting point: 128°C, softening point: 85°C) in a ratio of 1:1:1 (weight ratio) (melting point: approximately 107°C, softening point: 65°C), and the nickel powder was manufactured by Inco, trade name # 123 (average particle size approximately 3 to 7 μm) and #255 in 1:
A mixture of 1 (weight ratio) was used.

The composition consisting of the above formulation was dispersed in the same manner as Formulation 3 to create a liquid composition.

Next, in the same manner as in Formulation 1, a powdered resin composition (5) having a conductive fine powder/resin ratio of 80/20 (weight ratio) was prepared from the liquid composition.

[Formulation 6] Epoxy resin 9% Nickel powder (same as formulation 4) 51% Methyl ethyl ketone 40% Epoxy resin is manufactured by Ciel Chemical Co., Ltd. under the trade name Epicote #1002, #1004, #1007, and #1009 (epoxy equivalent 2400~ 3300, melting point approximately 148℃, softening point 90℃)
A mixture of 1:1:2:2 (weight ratio) (melting point: about 135°C, softening point: 75°C) was used.

A powdered resin composition (6) having a conductive fine powder/resin ratio of 85/15 (weight ratio) was prepared using the composition having the above formulation in the same manner as in Formulation 3.

[Composition 7] Epoxy resin 5.7% Graphite carbon powder 14% Methyl ethyl ketone 80% Dicyandiamide 0.3% The epoxy resin is Epicoat #1007, and the graphite carbon powder is a product name manufactured by Chuetsu Graphite Industries Co., Ltd.
CX-3000 (median particle size approximately 3 μm) was used.

A liquid composition was prepared using the composition described above in the same manner as in Formulation 1, 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 parts).
^m2 /min, liquid composition supply rate 200ml/min, inlet air temperature 95°C, outlet air temperature 30°C), a powdered resin composition (70/30 (weight ratio) of conductive fine powder/resin) )It was created.

[Blend 8] Polyester resin 12% Dendrite-shaped copper powder (same as Blend 2) 48% Methyl ethyl ketone 40%
75℃) was used.

A liquid composition was prepared by dispersing the composition consisting of the above formulation in a magnetic pot mill for 1.5 hours, and the conductive fine powder/
A powdered resin composition (8) with resin = 80/20 (weight ratio) was prepared.

[Formulation example 9] Polyester resin (same as formulation 8) 12% Nickel powder (same as formulation 5) 48% Methyl ethyl ketone 40% A composition consisting of the above formulation was prepared in the same manner as formulation 7 to obtain conductive fine powder/resin = 80/ A powdered resin composition (9) having a weight ratio of 20 was prepared.

[Composition 10] Polyester resin 9% Copper powder 51% Methyl ethyl ketone 40% Polyester resin is manufactured by Nippon U-Pica Co., Ltd. under the trade name GV
-110 (melting point 85℃, softening point 65℃), copper powder manufactured by Fukuda Metal Foil Powder Co., Ltd. under the trade name 4L3 (350 mesh pass 95
% or more) were used respectively.

A powdered resin composition (10) with conductive fine powder/resin=85/15 (weight ratio) was prepared by using the composition consisting of the above formulation in the same manner as Formulation 8.

[Formulation 11] Acrylic resin 9% Nickel powder (same as formulation 4) 51% Methyl ethyl ketone 40% Acrylic resin is manufactured by Dainippon Ink Chemical under the trade name A-
224S (melting point 114°C, softening point 70°C) was used.

A powdered resin composition (11) with conductive fine powder/resin=85/15 (weight ratio) was prepared by using the composition consisting of the above formulation in the same manner as in Formulation 5.

A coating composition was also produced according to the following formulation.

[Formulation A]

Styrenic acrylic copolymer 22 parts Nitrified cotton (1/4 second) 12 Azo pigment (Shinka Sharetsu) 6 Solvent (1:4:5 mixture of isobutyl alcohol, ethyl acetate, and toluene) 55 parts Consisting of the above formulation The composition was dispersed using three rollers to obtain a coating composition (A).

[Formulation B]

Styrenic acrylic copolymer 22 parts Nitrified cotton (1/4 second) 11 Phthalocyanine blue 6 Solvent (same as formulation A) 56 The composition consisting of the above formulation was dispersed with three rollers to form a coating composition (B). I got it.

[Formulation C]

Acrylic polyol resin 40 parts Azo red pigment (Shinka Shared) 7 Solvent (same as formulation A) 53 The composition consisting of the above formulation was dispersed with three rollers to obtain a coating composition (C).

[Formulation D]

Acrylic polyol resin 40 parts Phthalocyanine blue 7 Solvent (same as formulation A) 53 parts The composition consisting of the above formulation was dispersed with three rollers to obtain a coating composition (D).

[Formulation E]

Styrenic acrylic copolymer 20 parts Nitrified cotton (1/4 second) 10 Titanium oxide (rutile type) 15 Solvent (same as formulation A) 55 The composition consisting of the above formulation was dispersed with three rollers to form a coating composition. Obtained item (E).

[Formulation F]

Styrenic acrylic copolymer 23 parts Nitrified cotton (1/4 second) 10 Carbon black 2 Solvent (same as formulation A) 65 The composition consisting of the above formulation was dispersed with three rollers to form a coating composition (F). I got it.

[Formulation G]

Acrylic polyol resin 45 parts Solvent (same as formulation A) 55 The composition consisting of the above formulation was dissolved and stirred to obtain a coating composition (G).

[Formulation H]

Acrylic resin 10 parts Nitrified cotton (1/4 second) 6 Titanium oxide (rutile type) 7.85 Carbon black 0.15 Talc 10 Precipitated barium sulfate 12 Solvent (same as formulation A) 54 A composition consisting of the above formulation was heated in a magnetic pot mill for 2 hours. After time dispersion, a coating composition (H) was obtained.

[Formulation I]

Urethane resin 20 parts Titanium oxide (rutile type) 19 Carbon black 1 Precipitated barium sulfate 15 Solvent (1:1:1 mixture of methyl ethyl ketone, xylene, and toluene) 45 The composition consisting of the above formulation was mixed with a magnetic pot mill for 2 After time dispersion, a coating composition (I) was obtained.

Example 1 After masking the non-painted part in the fixed mold that was preheated to 70°C, the powdered resin composition (1) was poured into the mold.
Electrostatic painting was applied under a voltage of 80KV to form a coating film, and then the masking was removed and the stationary mold and moving 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/cm ² .

In this way, a heat-resistant polystyrene molded article having a uniform and highly conductive film with a film thickness of 42 μm and a surface resistance value of 0.90 ohm/□ was obtained.

Then, the coating composition (A) was air-sprayed onto the conductive film and dried to form a protective film with a thickness of 30 μm.

Example 2 The non-painted parts of the fixed mold, which had been preheated to 60°C, were masked, and the powdered resin composition (2) was heated to -70KV.
After applying electrostatic coating under the voltage of , forming a coating film,
I removed the masking. Next, the fixed mold and the movable mold were sealed, and a vinyl chloride resin liquid with a resin temperature of 180°C was injection molded at an injection pressure of about 750 kg/cm ² .
Uniform film thickness of 55 μm, surface resistance value of 0.52 ohm/□,
A vinyl chloride resin molded article having a highly conductive film was obtained.

Then, the coating composition (B) was applied onto the conductive film in the same manner as in Example 1 to obtain an aesthetically finished film with a thickness of 25 μm.

Example 3 The non-painted parts in a mold that had been preheated to 90°C were masked, and then the powdered resin composition (3) was applied to the inside of the mold using an electrostatic coating device under a voltage of -65 KV. After painting the area and forming a paint film, the masking was removed. Then, the hard vinyl chloride sheet was heated to 125°C using a heater to soften it, and it was fixed to the above-mentioned mold with a clamp frame, and then the air inside the mold was pumped out with a vacuum level of 720 mmHg using a vacuum pump. When sucked out, the sheet was closely attached to the mold surface and molded, the film thickness was 45 μm and the surface resistance value was
A hard vinyl chloride resin molded body having a uniform and highly conductive film of 0.40 ohm/□ was obtained.

Then, the coating composition (C) was applied on the obtained conductive film in the same manner as in Example 1 to obtain a protective and/or aesthetic finishing film with a thickness of 30 μm.

Example 4 The unpainted parts of the fixed mold, which had been preheated to 65°C, were masked, and the powdered resin composition (4) was electrostatically applied under a voltage of -60KV to form a coating film, and the masking was removed. did. Next, the fixed mold and the movable mold were sealed, and a polyethylene resin liquid with a resin temperature of 220°C was injection molded at an injection pressure of approximately 1100 kg/ ^cm2 .
A polyethylene resin molded body having a uniform and highly conductive coating with a surface resistance of 50 μm and a surface resistance of 0.90 ohm/□ was obtained.

Then, the coating composition (D) was applied onto the conductive film in the same manner as in Example 1 to obtain an aesthetically finished film with a thickness of 35 μm.

Example 5 After masking the unpainted part of the fixed mold at a temperature of 60°C and electrostatically coating the powdered resin composition (5) under a voltage of -70 KV, the masking was removed and the mold was heated with an infrared heater. It was heated to 95°C to form a coating film. Next, the fixed mold and the movable mold are sealed, and ABS resin liquid with a resin temperature of 230°C is injection molded at an injection pressure of approximately 1000 kg/cm ² to form a uniform and good film with a thickness of 65 μm and a surface resistance value of 0.35 ohm/□. ABS with conductive coating
A resin molded body was obtained.

Next, the coating composition (H) was coated with a primer on the conductive film, and then the coating composition (E) was coated in the same manner. A protective coating with a total thickness of 55 μm was thus obtained.

Example 6 The unpainted part of the inner surface of the mold, which had been preheated to 87°C, was masked, and the powdered resin composition (6) was applied to the inner surface of the mold under a voltage of -60 KV using an electrostatic powder coating device. After painting the painted area and removing the masking, the inner surface of the mold is heated with an infrared heater to form a coating film. Polypropylene extruded into a tube shape at 195℃ is inserted into the above mold, and 3.5 kg / cm is placed inside the tube. Blow in the compressed air from ^{Step 2} to inflate it.
When polypropylene was closely adhered to the inner surface of the mold and molded, a polypropylene resin molded body having a uniform and highly conductive film with a film thickness of 65 μm and a surface resistance value of 0.85 ohm/□ was obtained.

Next, the conductive film was coated with a primer coat of the paint composition (H), and then finished with a top coat of the paint composition (F).

Example 7 The non-painted parts in a mold preheated to 125°C were masked, and the powdered resin composition (7) was applied inside the mold under a voltage of -70 KV using an electrostatic powder coating device. After painting the painted area and forming a coating film, remove the masking, put the phenol resin powder preheated to 116℃ into the mold, close the mold, and apply 155℃.
When heated to 180 kg/cm ² and compressed using a mold, a phenolic resin molded article having a uniform and highly conductive coating with a thickness of 55 μm and a surface resistance of 250 ohms/□ was obtained.

Then, the film thickness was adjusted in the same manner as in Example 5.
A beautiful finished film of 60 μm was obtained.

Example 8 The non-painted parts of the mold were preheated to 120°C, and the powdered resin composition (8) was electrostatically applied under a voltage of -70KV to form a coating film, and then the masking was removed. I removed it. Then, 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/cm ² to form a film with a thickness of 45 μm.
A polycarbonate resin molded body having a uniform and highly conductive coating with a surface resistance value of 1.5 ohm/□ was obtained.

Then, after primer coating in the same manner as in Example 5, coating composition (G) was applied to obtain a protective film with a thickness of 45 μm.

Example 9 The non-painted part in the mold, which was preheated to 150°C, was masked, and the powdered resin composition (9) was heated to -60KV.
After electrostatic painting was carried out under an electrostatic voltage of 100 mL to form a coating film, the masking was removed. Then, the fixed mold and the movable mold were sealed, and PPO (polyphenylene oxide) resin with a resin temperature of 330° C. was injection molded at an injection pressure of 1500 kg/cm ² to obtain a PPO resin molded body. The surface conductive coating had a good electrical conductivity with an average thickness of 58 μm and a surface resistance value of 0.93 ohm/□, although some unevenness occurred on the coating surface near the nozzle where the resin was injected.

Then, after coating the coating composition (I) as a primer on the film, coating composition (C) is applied as a top coat to adjust the film thickness.
A beautiful finished film of 50 μm was obtained.

Example 10 After masking the unpainted part of the inner surface of a mold that had been preheated to 90°C, the powdered resin composition (10) was applied to the painted part of the mold using an electrostatic powder coating device. Remove masking and form coating film
The polyethylene resin extruded into a tube shape at 175℃ was inserted into the above mold, and compressed air of 3.2 kg/cm ² was blown into the tube to inflate it and adhere to the inner surface of the mold. When molded, the film thickness was 50 μm and the surface resistance value was
A polyethylene resin molded body having a uniform and highly conductive coating of 0.65 ohm/□ was obtained.

Then, after primer coating in the same manner as in Example 9, coating composition (D) was applied as a top coat to obtain a beautiful finished film with a thickness of 50 μm.

Example 11 The non-painted part in the mold was preheated to 105°C, and the powdered resin composition (11) was heated to -80KV.
Electrostatic coating was applied at a voltage of 100 mL, and after a coating film had been formed, the masking was removed. Next, the fixed mold and the movable mold were sealed, and a polypropylene resin liquid with a resin temperature of 240°C was injection molded at an injection pressure of 1500 kg/cm ² to form a film with a thickness of 45 μm.
A polypropylene resin molded body having a uniform and highly conductive coating with a surface resistance value of 0.31 ohm/□ was obtained.

Then, after primer coating in the same manner as in Example 9, coating composition (A) was applied as a top coat to obtain an aesthetically finished film with a thickness of 45 μm.

[Brief explanation of drawings]

FIGS. 1A to 1E are process schematic diagrams showing an injection molding method that is an example of the method of the present invention. FIG. 2 is an enlarged view of the dotted line in step D in FIG. 1, and FIG. 3 is a sectional view of a plastic molded article obtained by the method of the present invention. 1... Plastic molded body, 2... Conductive film, 3
...Molding mold, 4. Masking material, 5. Electrostatic coating machine, 6. Beautiful decoration and/or protective coating.

Claims (1)

[Claims] 1. In a plastic molding method, a powdered thermosetting or thermoplastic resin composition containing conductive fine powder is applied into a mold by electrostatic coating, and then a plastic material is filled and molded, The powdered resin composition is plasticized and compressed using the heat of the filling material and/or the heat during molding to form a conductive thermosetting or thermoplastic resin coating on the surface of the molded plastic, and after demolding,
A plastic molding method in which a liquid paint composition is applied to the film at room temperature and dried to form a protective and/or aesthetic film. 2. The plastic molding method according to claim 1, wherein the plastic molding method is an injection molding method, a blow molding method, or a vacuum forming method. 3. The plastic molding method according to claim 1 or 2, wherein the mold is a preheated mold. 4. Claim No. 4, in which a powdered thermosetting or thermoplastic resin composition is applied inside a mold by electrostatic coating, and then the powdered resin composition is fused or cured by heating, and then molded. The plastic molding method according to item 1, item 2, or item 3. 5 The melting point and softening point of the resin component used in the powdered resin composition and the mold preheating temperature are (melting point + 10°C)
4. The method of producing plastics according to claim 3, wherein the range is ≧mold preheating temperature≧softening point. 6. The powdered resin composition is obtained by dispersing, granulating, and solvent extracting a liquid composition consisting of a water-soluble solvent, the water-insoluble and solvent-soluble resin, and a conductive fine powder in water, followed by separation and drying. The plastic molding method according to claim 1, which is a powdered resin composition obtained by a wet granulation method. 7. The plastic molding method according to claim 1, wherein the conductive fine powder is a dendrite-shaped metal fine powder. 8. The plastic molding method according to claim 1, wherein the coating composition is a composition containing 1 to 70% by weight of a colored pigment. 9. The plastic molding method according to claim 1, wherein the coating composition contains 1 to 50% by weight of conductive carbon. 10. The plastic molding method according to claim 1, wherein the coating composition contains 20 to 70% by weight of conductive fine powder other than conductive carbon.