JP2005171024A - White conductive primer coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white conductive primer coating which has a conductivity sufficient for electrostatically coating a plastic substrate with a primer coating and can form a coating film having high brightness. <P>SOLUTION: This white conductive primer coating comprises (a) a resin component comprising a chlorinated polyolefin resin having a specific chlorination degree, (b) a mica pigment coated with a conductive metal oxide such as tin oxide or antimony-doped tin oxide, and (c) white conductive titanium dioxide powder which has a conductive layer containing tin oxide and phosphorus on the surface of each titanium dioxide particle and contains a metal element having an atomic valency of ≤3 in the following content (A) of ≤0.1. (A)=(M<SB>1</SB>)×(4-n<SB>1</SB>)+ ...+(M<SB>X</SB>)×(4-n<SB>X</SB>) (M<SB>1</SB>, ..., M<SB>X</SB>are each an atomic ratio of a metal element having an atom valency of ≤3 to Sn in the powder; n<SB>1</SB>, ..., n<SB>X</SB>are each the valency of each metal element; X of M<SB>X</SB>and n<SB>X</SB>is the number of the metal element and the natural number of ≥1). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a white conductive primer coating.

  Conventionally, plastic substrates such as automobile bumpers have been painted by spraying such as air spray or airless spray. However, in order to save energy and reduce the discharge of harmful substances to the environment, the coating efficiency is excellent. Many electrostatic coatings have been adopted.

Since a plastic substrate generally has a high electric resistance value (usually about 10 ¹² to 10 ¹⁶ Ω / □), it is extremely difficult to directly apply a paint on the plastic surface by electrostatic coating. Therefore, electrostatic coating is usually performed after imparting conductivity to the plastic substrate itself or its surface so that the surface electrical resistance value is less than 10 ⁹ Ω / □.

  For example, in electrostatic coating of a paint on a plastic substrate, a conductive primer coating is applied in advance to impart conductivity to the substrate. As the conductive primer paint, a paint containing a resin component and a conductive filler is usually used.

  Conventionally, particles such as conductive carbon, metal, and conductive metal oxide have been used as the conductive filler. Moreover, as the particle shape of the conductive filler, a powdery, needle-like, fibrous or spherical one is usually used.

  However, when the above conventional conductive filler is used, the primer coating generally has a low brightness, and there is a problem that the whiteness and light color tone of the high-brightness top coat are impaired.

  As a conductive filler capable of solving the above problems, white conductive material having a tin oxide coating layer containing 0.1 to 10% by weight of phosphorus formed on the surface of titanium dioxide particles using tin oxide doped with phosphorus. It is known that titanium dioxide powder can be used in paint (see Patent Document 1).

  However, the white conductive titanium dioxide powder has a problem that it is difficult to form a layer having good conductivity on the surface of the titanium dioxide particles. Therefore, the coating film obtained by applying the white conductive primer paint added with this powder as a conductive filler cannot obtain stable conductivity, and the electrostatic coating suitability of the coating film is not sufficient. In addition, in order to improve the conductivity of the coating film, increasing the amount of the titanium dioxide powder added to the primer coating results in insufficient dispersibility in the coating and decreases the finish of the coating film. was there.

In addition, the surface of white inorganic pigment particles such as titanium dioxide, aluminum oxide, silicon dioxide, zinc oxide, barium sulfate, zirconium oxide, alkali metal titanate, muscovite, etc., the lower layer is a tin dioxide layer, and the upper layer is an oxide containing tin dioxide. A white conductive resin composition containing a white conductive powder coated with a double conductive layer of an indium layer and a resin is known (see Patent Document 2). However, in the resin composition using such white conductive powder, when the organic solvent-based top coating is applied wet-on-wet on the coating film, the primer coating film is formed by the organic solvent penetrating from the top coating film. As a result, the conductive path is cut and electrostatic coating cannot be performed.
Japanese Patent No. 3357107 Japanese Patent Laid-Open No. 7-14430

  An object of the present invention is to provide a white conductive primer coating having a sufficient conductivity for electrostatic coating of a top coating on a plastic substrate and capable of forming a high-lightness coating. There is.

  As a result of examining various reasons why it is difficult to form a layer having good conductivity on the surface of the titanium dioxide particles in the white conductive titanium dioxide powder of Patent Document 2, the present inventor as an impurity in the raw material titanium dioxide particles. The contained metal element having a valence of 3 or less diffuses into the coating layer by firing at the time of forming the phosphorus-containing tin oxide coating layer, which is a conductive layer, and lowers the conductivity, and is originally contained as an impurity in the conductive layer. It has been found that metal elements having a valence of 3 or less also lower the conductivity.

  Based on the above findings, the present inventor has intensively studied to develop a white conductive primer paint that has sufficient conductivity on a plastic substrate and can form a high-lightness coating film. As a result, a pigment in which the surface of mica is coated with a specific conductive metal oxide on a specific chlorinated polyolefin resin, and white conductive titanium dioxide powder having a specific amount or less of a metal element having a valence of 3 or less as an impurity According to the primer paint blended in a specific ratio as a conductive filler, sufficient conductivity can be stably imparted to the plastic substrate, resulting in high coating efficiency on the coating film and environmental impact. It has been found that electrostatic coating with a small amount of light is possible, and that the coating film has high brightness, that is, high whiteness.

  As a result of further various studies based on the new knowledge, the present inventor has completed the present invention.

  The present invention relates to the following white conductive primer paint and a method for forming a multilayer coating film using the same.

1. (A) 100 parts by weight of a resin component containing a chlorinated polyolefin resin having a chlorination rate of 10 to 35% by weight, and (b) tin oxide, antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), fluorine At least one conductive metal oxide selected from the group consisting of doped tin oxide (FTO), phosphorus-doped tin oxide, zinc antimonate, indium-doped zinc oxide, ruthenium oxide, rhenium oxide, silver oxide, nickel oxide and copper oxide 1 to 150 parts by weight of pigment coated on the surface of mica, and (c) the content of a metal element having a valence of 3 or less as an impurity, having a conductive layer containing tin oxide and phosphorus on the surface of titanium dioxide particles. 1 to 150 parts by weight of white conductive titanium dioxide powder which is 0.1 or less as (A) determined by the following formula (1) White conductive primer coating which,
Formula (1): (A) = (M ₁ ) × (4-n ₁ ) + (M ₂ ) × (4-n ₂ ) + (M ₃ ) × (4-n ₃ ) + (M ₄ ) × (4-n ₄ ) +... + (M _X ) × (4-n _X )
(Here, M ₁ , M ₂ , M ₃ , M ₄ ,..., M _X are the atomic ratios of metal elements having a valence of 3 or less to Sn of tin oxide in the white conductive titanium dioxide powder, _{n 1, n 2, n 3} , n 4, ..., n X _{is, M 1, M 2, M} 3, M 4, ..., indicate the respective valences of metal elements having atomic ratios of M _X, M _{X of X} and n _X represents the number of the metal elements contained in the white conductive titanium dioxide powder and can take a natural number of 1 or more.)

2. Item _2. The coating amount of tin oxide forming a conductive layer in the white conductive titanium dioxide powder (c) is in the range of 0.03 to 0.3 g as SnO ₂ per 1 m ^{2 of} titanium dioxide surface area. White conductive primer paint.

  3. Item 2. The item 1, wherein the white conductive titanium dioxide powder (c) has a phosphorus content in the conductive layer in a P / Sn atomic ratio of 0.10 to 0.50 with respect to tin oxide. White conductive primer paint.

4). The above item wherein the content of a metal element having a valence of 3 or less as an impurity contained in titanium dioxide in the white conductive titanium dioxide powder (c) is 0.02 or less as (B) determined by the following formula (2) The white conductive primer paint according to 1,
Formula (2): (B) = (M ′ ₁ ) × (4-n ′ ₁ ) + (M ′ ₂ ) × (4-n ′ ₂ ) + (M ′ ₃ ) × (4-n ′ ₃ ) + (M ′ ₄ ) × (4-n ′ ₄ ) +... + (M ′ _Y ) × (4-n ′ _Y )
(Here, M ′ ₁ , M ′ ₂ , M ′ ₃ , M ′ ₄ ,..., M ′ _Y are atomic ratios of metal elements having a valence of 3 or less with respect to Ti of titanium dioxide, and n ′ _{1 , n'2, n'3, n'} 4, ..., n'Y _{is, M'1, M'2, M'} 3, M'4, ..., each of the metal elements having atomic ratios of _M'Y And _Y of M ′ _Y and n ′ Y represents the number of the metal elements contained in titanium dioxide, and can take a natural number of 1 or more).

  5). Furthermore, (d) The white electroconductive primer coating material of any one of said claim | item 1-4 containing 200 weight part or less of white pigments.

6). The coating film obtained by coating on a plastic substrate and drying or curing is a coating film having a brightness (L ^* value) of 80 or more based on the L ^* a ^* b ^* color system defined in JIS Z 8729. Item 6. The white conductive primer paint according to any one of Items 1 to 5.

7). 7. The white conductive primer paint according to any one of the above items 1 to 6, wherein the surface electrical resistance value of a coating film obtained by coating on a plastic substrate and drying or curing is less than 10 ⁹ Ω / □.

8). (1) A step of coating a plastic substrate with the white conductive primer paint according to Item 1 so that the dry film thickness is about 10 to 45 μm, and setting or preheating.
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat one-bake in which the three-layer coating film comprising the primer paint, the colored base paint and the clear paint is simultaneously heated and baked.

9. (1) A step of coating the plastic substrate with the white conductive primer paint according to the above item 1 so that the dry film thickness is about 10 to 45 μm, and heat curing.
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat two-baking, in which the two-layer coating film comprising the above colored base coating and clear coating is simultaneously heated and baked.

  According to the white conductive primer paint of the present invention, the following special effects can be obtained.

(1) As a conductive filler, a pigment whose surface of mica is coated with a specific conductive metal oxide (hereinafter sometimes referred to as “conductive metal oxide-coated mica pigment”) (b) and titanium dioxide particles According to the white conductive primer paint of the present invention containing a specific amount of white conductive titanium dioxide powder (c) having a stable conductive layer on the surface, the surface electrical resistance value is less than 10 ⁹ Ω / □. A coating film can be easily formed.

  Therefore, electrostatic coating of a top coating such as a colored coating and / or a clear coating can be performed on the coating film, and energy saving and reduction of discharge of harmful substances to the environment can be achieved.

  (2) Use of conductive metal oxide-coated mica pigment (b) and white conductive titanium dioxide powder (c) as the conductive filler reduces the amount of powder (c) added to the primer coating. Even if it carries out, the conductive path of a white conductive primer coating film is securable. Therefore, by reducing the blending amount of the powder (c), it is possible to improve the dispersibility of the entire conductive filler in the primer paint, thereby preventing the finish of the coating film from being lowered.

  (3) In addition, when an organic solvent-based top coat is applied wet-on-wet on the primer coating, the powder may be swelled by the organic solvent penetrating from the top coat. Since the pigment (b) which coat | covered the surface of mica with the electroconductive metal oxide particle entered between the particle | grains of (c), and a conductive path can be ensured, the electroconductivity of a coating film is stable.

(4) Further, the white conductive primer paint of the present invention contains a conductive metal oxide-coated mica pigment (b) and a white conductive titanium dioxide powder (c), so that a high-lightness coating film, for example, A coating film having a high whiteness of 80 or more can be formed as a lightness (L ^* value) based on the L ^* a ^* b ^* color system defined in JIS Z 8729. Therefore, the top coat film obtained by electrostatically coating the top coat paint such as a colored paint and / or a clear paint on the primer paint film can have a bright color tone.

White conductive primer coating The white conductive primer coating of the present invention is a coating suitable for direct coating on a plastic substrate, and can form a coating film having high conductivity and high brightness. .

  Therefore, the top coating can be suitably applied by electrostatic coating on the primer coating, and the top coating can have a bright color tone.

  The white conductive primer paint of the present invention comprises (a) a resin component containing a chlorinated polyolefin resin having a chlorination rate of 10 to 35% by weight, (b) tin oxide, antimony-doped tin oxide (ATO), tin-doped oxidation. At least one selected from the group consisting of indium (ITO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide, zinc antimonate, indium-doped zinc oxide, ruthenium oxide, rhenium oxide, silver oxide, nickel oxide and copper oxide A pigment whose surface of mica is coated with conductive metal oxide particles, and (c) a content of a metal element having a valence of 3 or less as an impurity having a conductive layer containing tin oxide and phosphorus on the surface of titanium dioxide particles Is a water-based paint containing a specific amount of white conductive titanium dioxide powder, which is 0.1 or less as (A) determined by the formula (1) Is an organic solvent-based paints.

Resin component containing chlorinated polyolefin resin (a)
As the resin component of the white conductive primer paint, a chlorinated polyolefin resin or a resin component in which the resin and a modified resin are used in combination is used. That is, as the resin component, it is necessary to use a chlorinated polyolefin resin from the viewpoint of improving the adhesion of the coating film. However, the flexibility and rigidity of the coating film can be adjusted to the chlorinated polyolefin resin. Further, a modified resin for improving the film forming property can be used in combination.

  The chlorinated polyolefin resin is a chlorinated polyolefin, and the base polyolefin is, for example, a radical homopolymer or copolymer of at least one olefin selected from ethylene, propylene, butene, methylbutene, isoprene and the like. And a radical copolymer of the olefin and vinyl acetate, butadiene, acrylic acid ester, methacrylic acid ester and the like. The chlorinated polyolefin can generally have a weight average molecular weight in the range of about 30,000 to 200,000, especially about 50,000 to 150,000, and the chlorination rate is 10 to 35% by weight. Within a range of degrees.

  If the chlorination rate is in the range of about 10 to 35% by weight, the solubility in the solvent does not decrease, so atomization during spray coating is sufficient, and the solvent resistance of the coating film does not decrease. .

  As the chlorinated polyolefin resin, chlorinated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, chlorinated ethylene-vinyl acetate copolymer and the like are particularly suitable. Moreover, what graft-polymerized the polymerizable monomer to the chlorinated polyolefin can also be used.

  Examples of the polymerizable monomer to be graft-polymerized include (meth) acrylic acid alkyl ester, (meth) acrylic acid alkoxyalkyl ester, glycidyl (meth) acrylate, an adduct of glycidyl (meth) acrylate and monocarboxylic acid, and hydroxyalkyl. (Meth) acrylate, acrylic acid, methacrylic acid and the like can be mentioned. The amount of these polymerizable monomers used is not particularly limited as long as it does not cause gelation, but it is usually preferably about 10 to 80% by weight, preferably 30 to 60% by weight based on chlorinated polyolefin. More preferred is the degree.

  When the primer paint of the present invention is an aqueous paint, a hydrophilic monomer such as polymerizable unsaturated dicarboxylic acid or anhydride thereof is added to the chlorinated polyolefin in order to impart water dispersibility to the chlorinated polyolefin resin. At least one of the above can be graft-polymerized by a known method.

  A polymerizable unsaturated dicarboxylic acid or an anhydride thereof is a compound having one polymerizable unsaturated bond and two or more carboxyl groups or an anhydride group in one molecule. For example, maleic acid and an anhydride thereof , Itaconic acid and its anhydride, citraconic acid and its anhydride, and the like. The amount of these hydrophilic monomers used is preferably about 10 to 90% by weight, more preferably about 30 to 80% by weight, based on the chlorinated polyolefin.

  Graft polymerization of the above monomer onto the chlorinated polyolefin resin can be performed by a method known per se. The modified chlorinated polyolefin obtained by using the polymerizable unsaturated dicarboxylic acid or its anhydride in the above-mentioned use amount usually has a saponification value of about 10 to 60 mgKOH / g, particularly about 20 to 50 mgKOH / g. .

  As described above, the chlorinated polyolefin resin graft-polymerized with the polymerizable unsaturated dicarboxylic acid or its anhydride has a part or all of the carboxyl groups contained in the molecule for water solubilization or water dispersion. It is preferable to neutralize with an amine compound.

  Examples of the amine compound include tertiary amines such as triethylamine, tributylamine, dimethylethanolamine, and triethanolamine; primary amines such as dimethylamine, dibutylamine, and diethanolamine. A surfactant may be used in combination with these amine compounds for water-solubilization or water-dispersion.

  In the resin component of the white conductive primer paint, a chlorinated polyolefin resin can be used in combination with a modified resin for adjusting the flexibility and rigidity of the coating film or improving the film-forming property. As such a modified resin, for example, an acrylic resin, a polyester resin, a polyurethane resin, or the like can be used. In the case of using the modified resin in combination, the use ratio is usually suitably about 10 to 50 parts by weight with respect to 100 parts by weight of the chlorinated polyolefin.

  As the acrylic resin that is the modified resin, a hydroxyl group-containing acrylic resin can be suitably used. When the primer paint of the present invention is a water-based paint, the acrylic resin preferably has a carboxyl group together with a hydroxyl group for solubility in water, dispersibility, crosslinkability, and the like.

  The hydroxyl group-containing acrylic resin is obtained by polymerizing a hydroxyl group-containing monomer, a (meth) acrylic acid alkyl ester monomer, and other monomers as required by a known polymerization method such as a solution polymerization method. Can be obtained.

  The hydroxyl group-containing monomer is a compound having a hydroxyl group and a polymerizable unsaturated group, and examples thereof include (meth) acrylic acid such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and the like. Examples thereof include monoesterified products with alkylene glycols having 2 to 10 carbon atoms.

  Examples of (meth) acrylic acid alkyl ester monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and hexyl (meth) acrylate. , (Meth) acrylic acid-2-ethylhexyl, (meth) lauryl acrylate, stearyl (meth) acrylate, and the like, and monoesterified products of (meth) acrylic acid and monoalcohols having 1 to 20 carbon atoms. it can.

  Other monomers include compounds having a polymerizable unsaturated bond other than hydroxyl group-containing monomers and (meth) acrylic acid alkyl ester monomers, such as (meth) acrylic acid and maleic acid. Carboxyl group-containing monomers of the above; epoxy group-containing monomers such as glycidyl (meth) acrylate; (meth) acrylamide, acrylonitrile, styrene, vinyl acetate, vinyl chloride and the like.

  The hydroxyl group-containing acrylic resin usually has a hydroxyl value of about 10 to 100 mgKOH / g, preferably about 50 to 90 mgKOH / g, and an acid value of about 10 to 100 mgKOH / g, preferably about 30 to 60 mgKOH / g. The number average molecular weight is about 2,000 to 100,000, preferably about 3,000 to 50,000.

  The polyester resin that is a modified resin can be usually obtained by an esterification reaction of a polybasic acid and a polyhydric alcohol. A polybasic acid is a compound (including anhydride) having two or more carboxyl groups in one molecule, and a polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule, Can be used. Furthermore, it can be modified with a monobasic acid, a higher fatty acid, an oil component, or the like.

  The polyester resin can have a hydroxyl group, and the introduction can be performed by using a trihydric or higher alcohol together with a dihydric alcohol. Further, the polyester resin may have both a hydroxyl group and a carboxyl group, and generally has a weight average molecular weight in the range of about 1,000 to 100,000, preferably about 1,500 to 70,000. It is preferable.

  The polyurethane resin that is a modified resin has one terminal isocyanate group in one molecule obtained by reacting a polyhydroxy compound, a polyisocyanate compound, and a compound having one active hydrogen in one molecule. A thing can be used conveniently. The number average molecular weight of the polyurethane resin is generally in the range of about 400 to 10,000, preferably in the range of about 1,000 to 4,000.

  The polyhydroxy compound has at least two alcoholic hydroxyl groups in one molecule, has a number average molecular weight of about 50 to 8,000, particularly about 50 to 6,000, and has a hydroxyl group equivalent. Those within the range of about 25 to 4,000, particularly about 25 to 3,000 can be preferably used. Examples of the compound include polyhydric alcohols, various polyester polyols or polyether polyols usually used in the production of polyurethane resins, and mixtures thereof.

  The polyisocyanate compound is a compound having 2 or more, preferably 2 or 3, isocyanate groups in one molecule. As this compound, what is normally used for manufacture of polyurethane resins, such as an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, an aromatic polyisocyanate compound, can be used conveniently, for example.

  The compound having one active hydrogen in one molecule is used for blocking the isocyanate group in the polyisocyanate compound, for example, monohydric alcohol such as methanol, ethanol, diethylene glycol monobutyl ether; Monovalent carboxylic acids such as propionic acid; monovalent thiols such as ethyl mercaptan; primary amines such as diethylenetriamine and monoethanolamine; secondary amines such as diethylamine; oximes such as methylethylketoxime.

  As the polyurethane resin that is a modified resin, when the primer paint of the present invention is an aqueous paint, a hydrophilic polyurethane resin that can be dissolved or dispersed in water can be suitably used.

  The hydrophilic polyurethane resin is prepared by reacting, for example, aliphatic and / or alicyclic diisocyanate, diol having a number average molecular weight of about 500 to 5,000, a low molecular weight polyhydroxyl compound and dimethylolalkanoic acid by a one-shot or multistage method. The urethane prepolymer obtained by neutralization can be obtained by elongation or emulsification while neutralizing, and in particular, the average particle diameter obtained by distilling off part or all of the organic solvent used in the production process Is preferably an aqueous dispersion of a self-emulsifying urethane resin having a thickness of about 0.001 to 1 μm.

  A commercially available product can be used as the polyurethane resin. Commercially available products include, for example, “Takelac W610” (trade name, manufactured by Takeda Pharmaceutical Co., Ltd.), “Neolet's R960” (trade name, manufactured by Generalka Resin Co., Ltd.), “Samprene UX-5100A” (Sanyo Chemical Industries ( Co., Ltd., trade name) can also be used.

  The white conductive primer coating is preferably used as a thermosetting coating by adding a crosslinking agent to the resin component in order to improve the coating performance such as water resistance. Examples of such crosslinking agents include polyisocyanate compounds having unreacted isocyanate groups, blocked polyisocyanate compounds in which the isocyanate groups of the polyisocyanate compounds are blocked with a blocking agent, melamine resins, epoxy resins, carbodiimide resins, oxazoline compounds, and the like. Can do.

  Examples of the polyisocyanate compound having an unreacted isocyanate group include fragrances such as tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), and metaxylylene diisocyanate (MXDI). Aliphatic diisocyanates; Aliphatic diisocyanates such as hexamethylene diisocyanate (HDI); Alicyclic diisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated MDI; Polyisocyanate compounds such as burette, uretdione, isocyanurate or adducts of diisocyanate compounds; relatively low molecular weight urethane prepolymers; Rukoto can.

  When the primer paint of the present invention is a water-based paint, it is preferable to use the polyisocyanate compound after making it hydrophilic. Hydrophilization of the polyisocyanate compound is achieved by, for example, introducing a hydrophilic group such as a carboxyl group, a sulfonic acid group or a tertiary amino group into the compound, and a neutralizing agent such as a hydroxycarboxylic acid such as dimethylolpropionic acid. It can be carried out by neutralization with ammonia, tertiary amine or the like. Also, for example, a polyisocyanate compound can be mixed and emulsified with a surfactant, and used as a so-called self-emulsifying type polyisocyanate compound.

  A commercial item can be used as a hydrophilic polyisocyanate compound. Examples of commercially available products include “Baihijoule 3100” (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hydrophilic hexamethylene diisocyanurate).

  The blocked polyisocyanate compound is obtained by adding a blocking agent to the isocyanate group of the polyisocyanate compound to form a block.

  Examples of such blocking agents include lactam compounds such as ε-caprolactam and γ-butyrolactam; oxime compounds such as methyl ethyl ketoxime and cyclohexanone oxime; phenol compounds such as phenol, para-t-butylphenol and cresol; n -Aliphatic alcohols such as butanol and 2-ethylhexanol; Aromatic alkyl alcohols such as phenyl carbinol and methyl phenyl carbinol; Ether alcohol compounds such as ethylene glycol monobutyl ether.

  Blocking of the polyisocyanate compound is performed by, for example, dispersing the compound with water using a suitable emulsifier and / or protective colloid agent since the blocked product is generally hydrophobic after blocking the compound with a blocking agent. be able to.

  Specific examples of the melamine resin include a methylolated melamine resin obtained by reacting melamine with formaldehyde; a portion obtained by reacting a methylolated melamine resin with a monoalcohol having 1 to 10 carbon atoms, or a fully etherified melamine resin. Can be used. As these melamine resins, those having an imino group can also be used. These may be either hydrophobic or hydrophilic, but hydrophilic melamine resins having a low degree of condensation and having a number average molecular weight of about 3,000 or less, particularly about 100 to 1,500, which are etherified with methanol are suitable. Yes. A commercial item can be used as this hydrophilic melamine resin. Examples of commercially available products include “Cymel 303” and “Cymel 325” (both are trade names, manufactured by Cytec Corporation).

  The epoxy resin is a resin having two or more epoxy groups in one molecule, and is effective for crosslinking and curing chlorinated polyolefin, acrylic resin, polyester resin, polyurethane resin and the like having a carboxyl group.

  Specific examples of the epoxy resin include a copolymer of an epoxy group-containing polymerizable monomer and a vinyl polymerizable monomer. Examples of the epoxy group-containing polymerizable monomer include glycidyl acrylate, glycidyl methacrylate, methyl glycidyl acrylate, and methyl glycidyl methacrylate. Examples of the vinyl polymerizable monomer other than the epoxy group-containing polymerizable monomer include (meth) acrylic acid alkyl ester, acrylonitrile, styrene, vinyl acetate, and vinyl chloride. The copolymerization reaction with these monomers can be carried out by a known method. The resulting polymer has an epoxy equivalent of about 20 to 2,800, particularly about 30 to 700, and a number average molecular weight of 3,000 to 100, It is preferably in the range of about 000, particularly about 4,000 to 50,000.

  Furthermore, a glycidyl etherified epoxy resin of bisphenol, a hydrogenated product thereof, a glycidyl etherified epoxy resin of an aliphatic polyhydric alcohol, a glycidyl ester type epoxy resin, an alicyclic epoxy resin, or the like can also be used as a crosslinking agent. The molecular weight of these epoxy resins is preferably in the range of about 250 to 20,000, particularly about 300 to 5,000.

  A commercially available product can be used as the carbodiimide resin. As a commercial item, "Carbodilite E-01", "Carbodilite E-02" (all are the Nisshinbo Co., Ltd. make, brand name) etc. can be mentioned, for example.

  The oxazoline compound is a hydrophilic compound having a carboxyl group and effective for crosslinking and curing chlorinated polyolefin, acrylic resin, polyester resin, polyurethane resin and the like. As the hydrophilic oxazoline compound, commercially available “Epocross WS-500” (trade name, manufactured by Nippon Shokubai Co., Ltd.) and the like can be used.

  The blending amount of these crosslinking agents is usually preferably in the range of about 0 to 50 parts by weight, particularly about 5 to 40 parts by weight per 100 parts by weight of the total solid content of the resin component (a) containing the chlorinated polyolefin resin. It is.

Pigment (b) whose surface of mica is coated with conductive metal oxide particles
The white conductive primer paint of the present invention uses, as a conductive filler, a white conductive titanium dioxide powder (c) and a pigment (b) in which the surface of mica is coated with a specific conductive metal oxide. It is a feature.

  Mica (mica) used as a conductive metal oxide to be coated has the advantage that the lightness of the coating film is hardly lowered and the dispersibility is good. The mica (mica) to be coated with the conductive metal oxide preferably has a scaly shape from the viewpoint of improving recyclability and conductivity.

  Examples of the conductive metal oxide include tin oxide, antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide, zinc antimonate, indium-doped zinc oxide, and ruthenium oxide. At least one selected from the group consisting of rhenium oxide, silver oxide, nickel oxide and copper oxide is used. Among these, antimony-doped tin oxide (ATO) is particularly preferable from the viewpoint of cost.

  The average particle size of the pigment (b) whose surface of the mica is coated with conductive metal oxide particles is preferably about 0.5 to 40 μm, and more preferably about 1 to 20 μm.

  A commercial item can be used as this pigment (b). Commercially available products include, for example, “Minatech 40CM” (trade name, manufactured by Merck Co., Ltd., scaly mica coated with antimony-doped tin oxide), “MEC500” (trade name, manufactured by Teika Co., Ltd., antimony-doped oxidation) And scaly mica whose surface is coated with tin).

White conductive titanium dioxide powder (c)
The white conductive titanium dioxide powder (c) is blended as a conductive filler in the primer paint of the present invention, and formed on the surface of the titanium dioxide particles using tin oxide doped with phosphorus. It has a conductive layer containing tin oxide and phosphorus, and the conductive titanium dioxide powder has a specific amount or less of metal elements having a valence of 3 or less as impurities.

  Phosphorus-doped tin oxide is a solution in which a portion of tetravalent tin ions constituting tin oxide is substituted with pentavalent phosphorus ions and is dissolved.

  The content of impurities contained in the white conductive titanium dioxide powder (c) means the total amount of impurities contained in the titanium dioxide particles and impurities contained in the conductive layer coated on the particle surfaces. Impurities contained in the titanium dioxide particles diffuse into the conductive layer and lower the conductivity together with the impurities originally contained in the conductive layer. Therefore, the smaller the impurity content, the better.

  In the present invention, as an index of the content of impurities, a value converted as (A) obtained by the following formula (1) is used based on tin of tin oxide contained in the conductive layer.

Formula (1): (A) = (M ₁ ) × (4-n ₁ ) + (M ₂ ) × (4-n ₂ ) + (M ₃ ) × (4-n ₃ ) + (M ₄ ) × (4-n ₄ ) +... + (M _X ) × (4-n _X )
In the formula (1), M ₁ , M ₂ , M ₃ , M ₄ ,..., M _X are, for example, metal elements having a valence of 3 or less, such as sodium, potassium, calcium, magnesium, zinc, aluminum, and iron. It is an atomic ratio of tin oxide to Sn in white conductive titanium dioxide powder.

  In the present invention, as the metal element, in addition to typical metal elements such as sodium, potassium, calcium, magnesium, zinc and aluminum, transition metal elements such as iron, boron, silicon, germanium, arsenic, antimony, selenium, tellurium and the like It shall contain a similar metal element. In the present invention, the atomic ratio is the ratio of the number of target metal atoms to the number of reference metal atoms.

M ₁ in the _{formula, M 2, M 3, M} 4, ..., the number of M _X is depending on the number of valence 3 or less of metal elements as impurities contained in the white conductive titanium dioxide powder, M _X X of can take a natural number of 1 or more.

When the white conductive titanium dioxide powder does not contain a metal element having a valence of 3 or less, M _X = 0. However, the impurity metal element having a valence of 3 or less does not include a metal element derived from an organometallic compound processed into a white conductive titanium dioxide powder after firing, such as a coupling agent described later. _{n 1, n 2, n 3} , n 4, ..., n X _{is, M 1, M 2, M} 3, M 4, ..., indicate the respective valences of metal elements having atomic ratios of M _X, n _X of X is the same numerical value as _X of M _X and can take a natural number of 1 or more.

  For example, sodium, potassium, etc. have a valence of 1, calcium, magnesium, zinc, etc. have a valence of 2, and aluminum, etc. have a valence of 3. Iron has a valence of 2 or 3. By multiplying the content of each metal element by the value obtained by subtracting the valence n of the metal element from the valence 4 of tin in the tin oxide, the influence of each impurity can be calculated, and the sum ( A) is the total impurity content.

  It is important that the total impurity content (A) is 0.1 or less, preferably 0.07 or less, more preferably 0.06 or less, still more preferably 0.02 or less, and most preferably 0.00. 001 or less.

  If the total impurity content of metal elements having a valence of 3 or less is at least within the above range, the desired conductivity can be obtained as the conductive filler, but if it is more than the above range, it is difficult to obtain the desired conductivity. . Quantitative analysis of tin, phosphorus, titanium and other impurity metal elements can be easily performed by fluorescent X-ray analysis, and the valence of the metal elements is XPS (X-ray photoelectron spectroscopy), ESR (electron spectroscopy). (Spin resonance).

  The formation of the conductive layer on the surface of the titanium dioxide particles can be performed by adding a tin compound and a phosphorus compound to an aqueous suspension of titanium dioxide powder and attaching it to an aqueous suspension, as described later. The formed conductive layer has a structure in which phosphorus is dissolved in tin oxide.

The coating amount of tin oxide forming the conductive layer can be set as appropriate, but it is preferably in the range of 0.03 to 0.3 g as SnO ₂ per 1 m ² of the surface area of titanium dioxide. Conductivity is obtained. On the other hand, if the amount is less than this range, it is difficult to form a continuous conductive layer, and it is difficult to obtain desired conductivity. If the amount is too large, it tends to precipitate on the surface of titanium dioxide and is not economical. A decrease in whiteness is also likely to occur. The amount of tin oxide is more preferably in the range of 0.05 to 0.2 g.

  The specific surface area of titanium dioxide or white conductive titanium dioxide powder (c) can be determined by the BET method.

  Further, the amount of phosphorus in the conductive layer can be appropriately set. However, a ratio of 0.10 to 0.50 as a P / Sn atomic ratio with respect to tin oxide is preferable. Conductivity is obtained. On the other hand, if the amount is less than this range, it is difficult to obtain desired conductivity, and if it is too much, the conductivity tends to decrease. The proportion of phosphorus is more preferably from 0.13 to 0.40, and even more preferably from 0.15 to 0.30.

  The conductive layer containing tin oxide and phosphorus preferably has a low content of metal elements having a valence of 3 or less, such as sodium, potassium, calcium, magnesium, zinc, aluminum, and iron.

  In the white conductive titanium dioxide powder (c), titanium dioxide for forming a conductive layer containing tin oxide and phosphorus is a metal element having a valence of 3 or less, such as sodium, potassium, calcium, magnesium, zinc, aluminum, and iron. It is preferable that the content of a metal element having a valence of 3 or less as an impurity contained in titanium dioxide is 0.02 or less as (B) determined by the formula (2).

Formula (2): (B) = (M ′ ₁ ) × (4-n ′ ₁ ) + (M ′ ₂ ) × (4-n ′ ₂ ) + (M ′ ₃ ) × (4-n ′ ₃ ) + (M ′ ₄ ) × (4-n ′ ₄ ) +... + (M ′ _Y ) × (4-n ′ _Y ).

In formula (2), M ′ ₁ , M ′ ₂ , M ′ ₃ , M ′ ₄ ,..., M ′ _Y are, for example, sodium, potassium, calcium, magnesium, zinc, aluminum, iron, etc. Is the atomic ratio of titanium dioxide to Ti. M ′ ₁ , M ′ ₂ , M ′ ₃ , M ′ ₄ ,..., M ′ _Y is an impurity contained in titanium dioxide, and _Y of M ′ Y is determined according to the number of metal elements having a valence of 3 or less. It can take a natural number of 1 or more.

When titanium dioxide does not contain a metal element having a valence of 3 or less, M ′ _Y = 0. However, the impurity metal element having a valence of 3 or less does not include a metal element derived from an organometallic compound processed into a white conductive titanium dioxide powder after firing such as a coupling agent described later.

_{n'1, n'2, n'3} , n'4, ..., n'Y _{is, M'1, M'2, M'} 3, M'4, ..., a metal having an atomic ratio of _M'Y The valence of each element is shown. _Y of n ′ Y is the same numerical value as _Y of M ′ Y and can take a natural number of 1 or more.

  For example, sodium, potassium, etc. have a valence of 1, calcium, magnesium, zinc, etc. have a valence of 2, and aluminum, etc. have a valence of 3. Iron has a valence of 2 or 3. By multiplying the content of each metal element by the value obtained by subtracting the valence n of the metal element from the valence 4 of tin in the tin oxide coated on the surface of the titanium dioxide particles, the influence of each impurity The total (B) is taken as the total impurity content in titanium dioxide.

  The total impurity content (B) is preferably 0.02 or less, more preferably 0.015 or less, and still more preferably 0.006 or less. If the total content of impurities in the titanium dioxide of metal elements having a valence of 3 or less is at least within the above range, the desired conductivity can be obtained, but if it is more than the above range, the desired conductivity is hardly obtained.

  Further, since a metal element having a valence of 4 or more reduces the mobility of conduction electrons generated by doping phosphorus with tin oxide, titanium dioxide includes a compound of a metal element having a valence of 4 or more as much as possible. Preferably not. Examples of such metal elements include silicon and niobium.

More specifically, as titanium dioxide, the total impurity content including a metal element having a valence of 3 or less and a metal element having a valence of 4 or more is 1.5% by weight with respect to TiO _{2 in} terms of anhydrous oxide. Or less, preferably 1.0% by weight or less, more preferably 0.5% by weight or less, further preferably 0.1% by weight or less, that is, the TiO ₂ purity is 98.5% by weight or more, preferably 99.0% by weight. As described above, a high-quality product of 99.5% by weight or more, more preferably 99.9% by weight or more is preferable.

  The particle shape and particle diameter of titanium dioxide used in the white conductive titanium dioxide powder (c) can be appropriately selected according to the use scene as the conductive filler. As the particle shape, for example, any of granular, substantially spherical, spherical, needle-like, fiber-like, columnar, rod-like, spindle-like, plate-like, and other similar shapes can be used. Of these, granular or spherical ones are preferred because they are less harmful to the human body when recycling plastic products coated with a primer paint using them.

  In addition, the average particle diameter of granular, substantially spherical, and spherical titanium dioxide is preferably about 0.01 to 3 μm, and more preferably about 0.03 to 0.3 μm.

  The particle shape and particle diameter of titanium dioxide are observed and measured from an electron micrograph.

  The crystal system of titanium dioxide used for the white conductive titanium dioxide powder (c) can be any of rutile, anatase, brookite, and amorphous crystal systems, but the same crystal system as that of tin oxide as the main component of the conductive layer. The rutile type titanium dioxide is preferable because conductivity is easily developed.

An organic substance may be adhered to the surface of the white conductive titanium dioxide powder (c) in order to improve the dispersibility in the resin. Examples of organic substances include silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconate coupling agents, zircoaluminate coupling agents, polyols, and siloxanes. The content of these organic substances is about 0.0001 to 0.4 g, more preferably about 0.0006 to 0.2 g, with respect to the surface area of 1 m ² of the white conductive titanium dioxide powder (b).

  When the white conductive titanium dioxide powder (c) is produced, the content of a metal element having a valence of 3 or less as an impurity contained in titanium dioxide is 0 as (B) determined by the above formula (2). It is important to use titanium dioxide that is 0.02 or less, preferably 0.015 or less, more preferably 0.006 or less.

Further, as a preferred embodiment, the total impurity content including a metal element having a valence of 3 or less and a metal element having a valence of 4 or more is 1.5% by weight or less with respect to TiO _{2 in} terms of anhydrous oxide, preferably 1.0% by weight or less, more preferably 0.5% by weight or less, further preferably 0.1% by weight or less, that is, the TiO ₂ purity is 98.5% by weight or more, preferably 99.0% by weight or more, more preferably Is preferably 99.5% by weight or more, more preferably 99.9% by weight or more of high-grade titanium dioxide.

  Such titanium dioxide is used in the production of conventional titanium dioxide such as chlorine method, sulfuric acid method, flame hydrolysis method, wet hydrolysis method, neutralization method, sol-gel method, sodium, potassium, calcium, magnesium, zinc. It can be produced by selecting a production method or production conditions that contain a metal element having a valence of 3 or less, such as aluminum, iron or the like, or all impurities in a specific amount or less.

  In addition, after manufacturing titanium dioxide containing a specific amount or more of impurities, the titanium dioxide containing impurities is treated with an acid or an alkali, or an alkali treatment after an acid treatment or an acid treatment after an alkali treatment. Three or less metal elements or all impurities can be removed to an amount in the above range. As the acid to be used, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid are suitable, and a 1 to 50% by weight aqueous solution of these acids is usually used. As the alkali, a 10 to 50% by weight aqueous solution of sodium hydroxide, potassium hydroxide or the like is used. In the acid treatment or alkali treatment, titanium dioxide may be added to the acid solution or alkali solution and stirred for 1 to 3 hours, and may be stirred while heating to 50 to 90 ° C. as necessary. Titanium dioxide having a desired grade can be obtained by each treatment with an acid or an alkali, but it is desirable to combine high acid grade titanium dioxide with a combination of acid treatment and alkali treatment.

  Such titanium dioxide is made into an aqueous suspension, and a tin compound and a phosphorus compound are added thereto, and the tin compound and the phosphorus compound are adhered to the surface of the titanium dioxide particles. There are various methods for attaching, but in the present invention, an acid aqueous solution and a alkaline aqueous solution in which a tin compound and a phosphorus compound are dissolved are prepared separately, and the pH of the aqueous suspension is adjusted to 2-6. It is important to add so as to maintain the range.

  If the pH of the aqueous suspension is within the above range, at least good conductivity can be obtained, but even if it is lower than this range or too high, tin compounds and phosphorus compounds hardly adhere to the titanium dioxide particle surface, It is difficult to obtain desired conductivity, and the content of a metal compound having a valence of 3 or less as an impurity increases. A preferred pH is in the range of 2-3. The titanium dioxide concentration of the aqueous suspension can be appropriately set, and is preferably 25 to 300 g / l, and preferably 50 to 200 g / l. Moreover, the temperature of aqueous suspension can be performed in the range of 50-95 degreeC, and the range of 60-80 degreeC is preferable.

  Various compounds can be used as the tin compound, and examples thereof include stannic chloride, stannous chloride, potassium stannate, sodium stannate, stannous fluoride, and stannous oxalate. Examples of phosphorus compounds include phosphorus trichloride, orthophosphoric acid, sodium hydrogen phosphate, trisodium phosphate, ammonium hydrogen phosphate, phosphorous acid, sodium dihydrogen phosphite, trisodium phosphite, phosphorus pentachloride. Etc. These tin compounds and phosphorus compounds can each be used alone or in combination of two or more.

Such tin compounds and phosphorus compounds are dissolved in inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid, or organic acids such as formic acid, acetic acid, oxalic acid and citric acid to prepare an aqueous acid solution. The addition amount of the tin compound may be an amount that allows a predetermined amount of tin oxide to adhere to the titanium dioxide, and the preferred range as SnO ₂ per 1 m ² of the surface area of the titanium dioxide particles corresponds to 0.03 to 0.3 g. A more preferable range is an amount necessary for coating with 0.05 to 0.2 g. Moreover, the addition amount of a phosphorus compound should just be the quantity which can dope predetermined amount with respect to a tin oxide, Preferably it is the quantity used as the ratio of 0.10-0.50 as P / Sn atomic ratio, More preferably The amount necessary for doping at a rate of 0.13 to 0.40, more preferably at a rate of 0.15 to 0.30. The concentrations of the tin compound and the phosphorus compound in the acid aqueous solution can be set as appropriate.

  Examples of the alkaline aqueous solution used to neutralize the acid aqueous solution of the above tin compound and phosphorus compound to adjust the pH to 2 to 6 include alkali metals such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate. At least one of hydroxides, carbonates and ammonia can be used.

  Next, the product in which the tin compound and the phosphorus compound are adhered to the surface of titanium dioxide is fractionated and fired at a temperature of 750 to 925 ° C. Fractionation is usually performed by filtering and washing as necessary. If alkali metal hydroxide or carbonate is used as the neutralizing agent, the alkali metal will be adsorbed to the product due to insufficient washing, and if left there will cause a decrease in conductivity, the alkali metal will not remain. It is preferable to perform sufficient washing.

  The product obtained by fractionation is then dried as necessary, and then calcined at a temperature of 750 to 925 ° C, preferably 800 to 900 ° C, more preferably 825 to 875 ° C. Firing can be performed in any of an oxidizing atmosphere, a reducing atmosphere, and an inert gas atmosphere, but it is advantageous to perform the firing in air. In the conventional method, it was necessary to fire at a temperature of 700 ° C. or lower, but in the present invention, coarsening and sintering of the particles of the material to be fired are substantially performed at a high temperature of 750 ° C. It is a great feature that it can be fired in the air without causing it, thereby easily imparting sufficient conductivity. The firing time varies depending on the apparatus type, processing amount, etc., and cannot be defined unconditionally, but it is 1 to 5 hours, preferably 1 to 2 hours. After firing, a pulverization treatment is performed according to a conventional method, and then the pH of the pulverized product can be adjusted or impurities can be removed as necessary. If necessary, the surface of the pulverized product can be treated with an organic substance by a wet method or a dry method.

  By the above, white electroconductive titanium dioxide powder (c) can be prepared suitably.

Composition of White Conductive Primer Paint The composition of the white conductive primer paint of the present invention is as follows: (b) tin oxide, antimony with respect to a total solid content of 100 parts by weight of the resin component (a) containing the chlorinated polyolefin resin Doped tin oxide (ATO), tin doped indium oxide (ITO), fluorine doped tin oxide (FTO), phosphorus doped tin oxide, zinc antimonate, indium doped zinc oxide, ruthenium oxide, rhenium oxide, silver oxide, nickel oxide and copper oxide 1 to 150 parts by weight of a pigment whose surface of mica is coated with at least one conductive metal oxide selected from the group consisting of 1 to 150 parts by weight of white conductive titanium dioxide powder (c).

  The amount of the conductive metal oxide-coated mica pigment (b) is in the range of 1 to 150 parts by weight, and the amount of the white conductive titanium dioxide powder (c) is in the range of 1 to 150 parts by weight. Thus, sufficient electrical conductivity can be imparted to the coating film, so that electrostatic coating can be suitably performed on the coating film, and the finished appearance and coating stability of the coating film are not impaired.

  The blending ratio of the conductive metal oxide-coated mica pigment (b) is preferably about 10 to 100 parts by weight, more preferably 30 to 80 parts by weight, based on 100 parts by weight of the total solid content of the resin component (a). About a part. The blending ratio of the white conductive titanium dioxide powder (c) is preferably about 10 to 200 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of the total solid content of the resin component (a). About a part.

  In addition, as described above, in the white conductive primer paint, in order to improve the coating performance such as water resistance, the resin component (a) is blended with the crosslinking agent and used as a thermosetting paint. Is preferred. As described above, the amount of the crosslinking agent is usually about 0 to 50 parts by weight per 100 parts by weight of the total solid content of the resin component (a).

  Furthermore, in a white electroconductive primer coating material, (d) white pigment can be mix | blended in order to improve the whiteness of the coating film obtained.

  Examples of the white pigment (d) include titanium dioxide (rutile type titanium dioxide, anatase type titanium dioxide, etc.), lead white, zinc white, zinc sulfide, lithopone and the like. From the aspect, titanium dioxide is preferable. More preferred is rutile titanium dioxide having an average particle size of about 0.05 to 2.0 μm, particularly about 0.1 to 1.0 μm.

  The blending amount of the white pigment (d) is about 200 parts by weight or less, preferably about 50 to 200 parts by weight, more preferably about 100 parts by weight of the total solid content of the resin component (a) including the chlorinated polyolefin resin. Is suitably about 70 to 180 parts by weight.

  The white conductive primer paint of the present invention is prepared by dissolving or dispersing the above-described components in an organic solvent or an aqueous medium by a method known per se, so that the solid content is about 15 to 60% by weight. It can be prepared by adjusting. The white primer paint may be either an organic solvent type or an aqueous type, but is preferably an aqueous white conductive primer paint from the viewpoint of low VOC.

Coating Method of White Conductive Primer Paint As the substrate on which the white conductive primer paint can be applied, various plastic substrates are preferable.

  Although it does not specifically limit as said plastic base material, For example, the various plastic members etc. which are used for the outer-plate part of motor vehicles, such as a bumper, a spoiler, a grill, and a fender, the outer-plate part of household appliances, etc. are mentioned.

  As a material for the plastic substrate, for example, polyolefin obtained by polymerizing at least one olefin having 2 to 10 carbon atoms such as ethylene, propylene, butylene, and hexene is particularly suitable, but is not limited thereto. A material such as polycarbonate, ABS resin, urethane resin, or nylon may be used. Further, these plastic substrates can be appropriately subjected to degreasing treatment, water washing treatment and the like in advance by a method known per se.

  The white conductive primer coating is usually adjusted to a viscosity of 12-18 seconds / Ford Cup # 4/20 ° C. and applied to a plastic substrate by a coating method such as air spray coating, airless spray coating, or immersion coating. , Can be suitably painted. The coating film thickness is about 5 to 50 μm, preferably about 20 to 45 μm in terms of dry film thickness.

By applying setting, preheating, heat drying, or heat curing to the coating film of this white conductive primer paint, a coating film having a surface electrical resistance value of less than 10 ⁹ Ω / □ can be usually formed. . When the surface electric resistance value is less than 10 ⁹ Ω / □, for example, a colored paint or / and a top paint such as a clear paint can be electrostatically coated on the coating film.

  As a means for pre-heating or heat-drying the coating film after the application of the white conductive primer paint, conventionally known drying means can be used, for example, air blow, infrared heating, far-infrared heating, induction heating, Examples thereof include dielectric heating.

The white conductive primer coating is a coating film having a high brightness, for example, a coating film having a high whiteness of 80 or more as a brightness (L ^* value) based on the L ^* a ^* b ^* color system defined in JIS Z 8729. Can be formed. This brightness is a value measured as follows. That is, the coating film obtained by spray-coating the paint (A) on a plastic substrate so as to have a dry film thickness of 30 to 40 μm, and then heating and drying at a temperature of 80 to 120 ° C. for 20 to 40 minutes. the lightness (L ^* value), colorimeter, for example, a value measured using Suga test Instruments Co., Ltd. the "color computer SM-7".

The lightness (L ^* value) of the coating film of the white conductive primer paint is preferably 85 or more.

  As a method of forming a light-colored multilayer coating film on a plastic substrate using the white conductive primer paint of the present invention, the following multilayer coating film forming method I by 3-coat 1-bake or 3-coat 2-bake I And II.

Multi-layer coating film forming method I: (1) A step of applying a white conductive primer paint of the present invention to a plastic substrate so that the dry film thickness is about 10 to 45 μm, and setting or preheating.
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat one-bake in which the three-layer coating film comprising the primer paint, the colored base paint and the clear paint is simultaneously heated and baked.

Multilayer coating film formation method II: (1) A process of applying a white conductive primer coating of the present invention to a plastic substrate so that the dry film thickness is about 10 to 45 μm, and heat-curing.
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat two-baking, in which the two-layer coating film comprising the above colored base coating and clear coating is simultaneously heated and baked.

  As the colored base paint in the above methods I and II, any paint known per se can be used as the colored paint for the topcoat base coat. For example, an acrylic resin or a polyester resin having a crosslinkable functional group such as a carboxyl group or a hydroxyl group Base resins such as alkyd resins, urethane resins and epoxy resins; cross-linking agents such as polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins and urea resins; and color pigments are dissolved or dispersed in water and / or organic solvents. What was made into a paint can be used conveniently.

  Moreover, a metallic pigment, a mica pigment, an extender pigment, dye, etc. can be suitably mix | blended with a coloring base coating material as needed. Among these, when a metallic pigment is blended, a metallic coating film having a dense feeling can be formed, and when a mica pigment is blended, a silky pearl coating film can be formed.

  As the clear paint in the above-mentioned methods I and II, any paint known per se can be used as the paint for the top coat, for example, an acrylic resin, a polyester resin having a crosslinkable functional group such as a carboxyl group and a hydroxyl group, A base resin such as an alkyd resin, urethane resin, or epoxy resin and a cross-linking agent such as a polyisocyanate compound, a blocked polyisocyanate compound, a melamine resin, or a urea resin are dissolved or dispersed in water and / or an organic solvent to form a paint. What was done can be used conveniently.

  In addition, a coloring pigment, a metallic pigment, an extender pigment, a dye, an ultraviolet absorber, and the like can be appropriately blended with the clear paint as necessary, so long as the transparency is not impaired.

  Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. Hereinafter, both “parts” and “%” are based on weight.

  In Examples, the following 1 and 2 were used as the pigment (b) whose surface of mica was coated with a conductive metal oxide.

  1. Scale-like mica whose surface is coated with antimony-doped tin oxide: trade name “Minatech 40CM”, manufactured by Merck & Co., Inc., average particle size of 10 to 20 μm, mica / silicon oxide 57% / antimony-doped tin oxide 43%.

  2. Scale-like mica whose surface is coated with antimony-doped tin oxide: trade name “MEC500”, manufactured by Teika Co., Ltd., average particle size of 10 μm.

Production Example 1 Production of White Conductive Titanium Dioxide Powder (c) As a raw material, a high-grade rutile titanium dioxide powder having an average particle size of 0.25 μm was used. This titanium dioxide was produced by the chlorine method, and a metal element having a valence of 3 or less as an impurity was below the detection limit, and (B) obtained by the formula (2) was 0. As elements other than metal elements having a valence of 3 or less as impurities, 0.02% of SiO _{2 and} 0.02% of SO ₃ are contained, and the purity of TiO ₂ is 99.96%. The specific surface area determined by the BET method is 6.6 m ² / g.

100 g of this high-grade rutile titanium dioxide powder was put into water to obtain a suspension having a concentration of 100 g / l. After adjusting the pH of the system to 2 to 3 by adding aqueous hydrochloric acid and heating to 70 ° C., 173 g of 50% aqueous solution of tin chloride (SnCl ₄ ) and 85% phosphoric acid (H ₃ PO ₄ ) are added therein. A solution prepared by mixing 1 g and 75 ml of 12N-hydrochloric acid solution and an aqueous sodium hydroxide solution were added in parallel over 60 minutes so as to maintain the pH of the suspension at 2 to 3, and phosphoric acid was added onto the titanium dioxide powder. A coating layer made of a hydrate of tin oxide containing The final pH of this suspension was 2. Further, the mixture was aged by stirring for 20 minutes while maintaining at 70 ° C.

  Next, the coated titanium dioxide powder was filtered, washed until the specific resistance of the filtrate reached 50 μS, and then dried at 120 ° C. overnight to recover the coated titanium dioxide powder. The recovered coated titanium dioxide powder is put into an electric furnace, fired in air at 850 ° C. for 1 hour, and then pulverized by a pulverizer to obtain white conductive titanium dioxide powder (this is referred to as conductive filler No. 1). And).

This conductive filler No. Tin oxide contained in 1 is 0.076g as surface area 1 m ² per SnO ₂ of titanium dioxide, phosphorus was the proportion of 0.17 at P / Sn atomic ratio with respect to tin oxide. In addition, the conductive filler No. The metal element having a valence of 3 or less as an impurity contained in 1 was below the detection limit, and (A) obtained by the formula (1) was 0. Metal elements other than metal elements having a valence of 3 or less as impurities were also below the detection limit.

Production Example 2 Production of White Conductive Titanium Dioxide Powder (c) In Production Example 1, a rutile type titanium dioxide powder having an average particle size of 0.25 μm containing a small amount of alumina is used instead of the high-grade rutile type titanium dioxide powder. A white conductive titanium dioxide powder (referred to as “conductive filler No. 2”) was obtained in the same manner as described above.

The titanium dioxide used was manufactured by the chlorine method, the aluminum content was 0.005 in terms of the atomic ratio of titanium dioxide to Ti, and other metal elements having a valence of 3 or less were not detected. (B) calculated | required by 2) is 0.005. Further, no metal element other than a metal element having a valence of 3 or less was detected, the TiO ₂ purity was 99.7%, and the specific surface area determined by the BET method was 6.8 m ² / g.

This conductive filler No. The tin oxide contained in ₂ was 0.074 g as SnO ² per 1 m ² of the surface area of titanium dioxide, and phosphorus was a ratio of 0.17 in terms of P / Sn atomic ratio with respect to tin oxide. Further, the atomic ratio of aluminum to Sn contained in this sample B was 0.019, and (A) represented by the formula (1) was 0.019.

Production Example 3 Production of White Conductive Titanium Dioxide Powder (b) In Production Example 1, a rutile type titanium dioxide powder having an average particle size of 0.25 μm containing a small amount of alumina was used instead of the high-grade rutile type titanium dioxide powder. A white conductive titanium dioxide powder (referred to as “conductive filler No. 3”) was obtained in the same manner as described above.

The titanium dioxide used was manufactured by the chlorine method, the aluminum content was 0.015 in terms of the atomic ratio of titanium dioxide to Ti, and other metal elements having a valence of 3 or less were not detected. (B) calculated | required by 2) is 0.015. Further, as an element other than a metal element having a valence of 3 or less, 0.1% of P ₂ O ₅ is contained, the TiO ₂ purity is 99.0%, and the specific surface area determined by the BET method is 7.1 m ² / g.

This conductive filler No. Tin oxide contained in 3 is 0.070g as surface area 1 m ² per SnO ₂ of titanium dioxide, phosphorus was the proportion of 0.17 at P / Sn atomic ratio with respect to tin oxide. In addition, this conductive filler No. The atomic ratio of aluminum contained in 3 to Sn was 0.057, other metal elements having a valence of 3 or less were not detected, and (A) obtained by the formula (1) was 0.057.

Production Example 4 Production of Chlorinated Polyolefin Resin for Water-Based Paint Chlorinated polypropylene (chlorine content 15%, maleic acid modification amount 2.0%, saponification value 30 mg KOH / g, weight average molecular weight 80,000) 500 parts, n- To a mixture (50 ° C.) consisting of 150 parts of heptane and 50 parts of N-methyl-pyrrolidone, 12 parts of dimethylethanolamine and a nonionic surfactant (trade name “Neugen EA-140”, manufactured by Daiichi Kogyo Kagaku Co., Ltd.) ) 5 parts were charged and stirred at the same temperature for 1 hour, and then 2,000 parts of deionized water were gradually added, followed by further stirring for 1 hour. Next, the pressure was reduced at a temperature of 70 ° C. to distill off a total of 600 parts of n-heptane and deionized water. 1 was obtained.

Production Example 5 Production of Chlorinated Polyolefin Resin for Water-Based Paint Manufactured using chlorinated polypropylene (chlorine content 35%, maleic acid modification amount 1.9%, saponification value 28 mg KOH / g, weight average molecular weight 60,000) In the same manner as in Example 4, a chlorinated polyolefin emulsion No. 24 having a solid content of 24% was used. 2 was obtained.

Production Example 6 Production of Acrylic Resin Solution for Water-Based Paint Acrylic resin reaction vessel equipped with a stirrer, thermometer, reflux condenser, etc. was charged with 40 parts of ethylene glycol monobutyl ether and 30 parts of isobutyl alcohol, heated and stirred at 100 ° C. Then, a mixture of the following monomers and the like was dropped over 3 hours.

Styrene 10 parts Methyl methacrylate 38 parts n-butyl acrylate 25 parts 2-hydroxyethyl methacrylate 20 parts Acrylic acid 7 parts 2,2'-Azobisisobutyronitrile 1 part Isobutyl alcohol 5 parts.

  After completion of dropping, the mixture was kept at 100 ° C. for 30 minutes, and then an additional catalyst solution which was a mixture of 0.5 part of 2,2′-azobisisobutyronitrile and 10 parts of ethylene glycol monobutyl ether was required for 1 hour. It was dripped. The mixture was further stirred at 100 ° C. for 1 hour, then cooled, and 15 parts of isobutyl alcohol was added. When the temperature reached 75 ° C., 4 parts of N, N-dimethylaminoethanol was added, and the mixture was stirred for 30 minutes. A water-soluble hydroxyl group- and carboxyl group-containing acrylic resin solution was obtained. The acrylic resin had a hydroxyl value of 86 mgKOH / g, an acid value of 54.5 mgKOH / g, and a number average molecular weight of 20,000.

Production Example 7 Production of Polyester Resin Solution for Organic Solvent Paint 240 parts of phthalic anhydride, 230 parts of trimethylolpropane and 175 parts of coconut oil fatty acid were esterified by a conventional method to obtain a polyester polyol resin solution. The hydroxyl value of this resin was 80 mgKOH / g, the acid value was 15 mgKOH / g, and the number average molecular weight was 8,000.

Example 1 Production of White Conductive Primer Paint For the 15 parts (solid content) of the acrylic resin solution obtained in Production Example 6, the conductive filler no. 80 parts of 1 was added, deionized water was added until the proper dispersion viscosity was reached, and then stirred for 30 minutes with a paint conditioner to obtain a dispersion paste.

  For this dispersion paste, chlorinated polyolefin emulsion no. 1 part 40 parts (solid content), urethane emulsion (trade name “Samprene UX-5100A”, Sanyo Chemical Industries Co., Ltd.) 30 parts (solid content), scaly mica (surface-coated with antimony oxide / tin oxide) 50 parts of a trade name “Minatech 40CM” (manufactured by Merck & Co., Inc.) was added, and the mixture was sufficiently stirred with a disper. Immediately before coating, 15 parts (solid content) of hydrophilic hexamethylene diisocyanurate (trade name “Baihijoule 3100”, manufactured by Sumika Bayer Urethane Co., Ltd.) was added, and the mixture was stirred thoroughly with a disper, and the viscosity was 15 seconds / Adjusted to Ford Cup # 4/20 ° C., aqueous white conductive primer paint no. 1 was obtained.

Examples 2 to 4 Production of White Conductive Primer Paint In the same manner as in Example 1, the aqueous white conductive primer paint no. 2-No. 4 was obtained.

Example 5 Production of White Conductive Primer Paint For 35 parts (solid content) of the polyester resin obtained in Production Example 7, the conductive filler No. 80 parts of 1 was added and toluene was added until the proper dispersion viscosity was obtained, and then stirred for 30 minutes with a paint conditioner to obtain a dispersion paste.

  To this dispersion paste, 50 parts (solid content) of chlorinated polyolefin (Note 1) for organic solvent-type paints and scaly mica (trade name “Minatech 40CM”, Merck 50 parts) was added and sufficiently stirred with a disper. Furthermore, just before coating, 15 parts of hexamethylene diisocyanurate (trade name “Sumijour N3300”, manufactured by Sumika Bayer Urethane Co., Ltd.) (solid content) was added, and the mixture was sufficiently stirred with a disper, and the viscosity was 15 seconds. / Ford Cup # 4 / Adjusted to 20 ° C., organic solvent type white conductive primer paint No. 5 was obtained.

  The above (Note 1) indicates the following.

  (Note 1) Chlorinated polyolefin for organic solvent type paint: toluene solution of maleic acid-modified chlorinated polypropylene, chlorine content 20%, acid value 35 mgKOH / g, weight average molecular weight 60,000.

  Table 1 shows the compositions of the white conductive primer paints of Examples 1 to 5.

表１における配合割合は、全て固形分の重量部を示す。

All blending ratios in Table 1 indicate parts by weight of solid content.

  In Table 1, (Note 2) to (Note 8) indicate the following.

  (Note 2) Minatec 40CM: Merck Co., Ltd., trade name, scaly mica whose surface is coated with antimony-doped tin oxide.

  (Note 3) MEC500: product name, scale-like mica whose surface is coated with antimony-doped tin oxide.

  (Note 4) JR-903: trade name, manufactured by Teika Co., Ltd., rutile titanium dioxide, average particle size 0.4 μm.

  (Note 5) Chlorinated polyolefin: Toluene solution of maleic acid-modified chlorinated polypropylene for organic solvent-type paint, chlorine content 20%, acid value 35 mgKOH / g, weight average molecular weight 60,000.

  (Note 6) Samprene UX-5100A: trade name, manufactured by Sanyo Chemical Industries, Ltd., urethane emulsion.

  (Note 7) Bihijoule 3100: trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hydrophilic hexamethylene diisocyanurate.

  (Note 8) Sumidur N3300: trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanurate.

Comparative Example 1 Production of White Conductive Primer Paint For the 15 parts (solid content) of the acrylic resin solution obtained in Production Example 6, the conductive filler no. 65 parts of 1 and 2.5 parts of conductive carbon (trade name “Ketjen Black EC600J”, manufactured by Lion Co., Ltd.) are added, deionized water is added until the proper dispersion viscosity is obtained, and then 30 minutes with a paint conditioner. Agitation was performed to obtain a dispersion paste.

  For this dispersion paste, chlorinated polyolefin emulsion no. 40 parts (solid content) of 2 and 30 parts (solid content) of urethane emulsion (trade name “Samprene UX-5100A”, manufactured by Sanyo Chemical Industries, Ltd.) were added and sufficiently stirred with a disper. Immediately before coating, 15 parts (solid content) of hydrophilic hexamethylene diisocyanurate (trade name “Baihijoule 3100”, manufactured by Sumika Bayer Urethane Co., Ltd.) was added, and the mixture was stirred thoroughly with a disperser. Adjusted to Ford Cup # 4/20 ° C., comparative aqueous white conductive primer paint no. 6 was obtained.

Comparative Examples 2 and 3 Production of White Conductive Primer Paint In the same manner as in Example 1, the aqueous white conductive primer paint No. 7 and no. 8 was obtained.

Comparative Example 4 Production of White Conductive Primer Paint For 35 parts (solid content) of the polyester resin obtained in Production Example 7, the conductive filler No. 130 parts of 1 was added, toluene was added until the proper dispersion viscosity was reached, and then stirred for 30 minutes with a paint conditioner to obtain a dispersion paste.

  To this dispersion paste, 50 parts (solid content) of chlorinated polyolefin (Note 1) for organic solvent-type paint was added and sufficiently stirred with a disper. Furthermore, just before coating, 15 parts of hexamethylene diisocyanurate (trade name “Sumijour N3300”, manufactured by Sumika Bayer Urethane Co., Ltd.) (solid content) was added, and the mixture was sufficiently stirred with a disper, and the viscosity was 15 seconds. / Ford Cup # 4 / Adjusted to 20 ° C., organic solvent type white conductive primer paint No. 9 was obtained.

  Table 2 shows the compositions of the white conductive primer paints of Comparative Examples 1 to 4.

表２における配合割合は、全て固形分の重量部を示す。

All blending ratios in Table 2 indicate parts by weight of solid content.

  In Table 2, (Note 9) to (Note 11) indicate the following.

  (Note 9) “Ketjen Black EC600J”: trade name, manufactured by Lion Corporation, conductive carbon.

  (Note 10) “Dentol WK500”: trade name, manufactured by Otsuka Chemical Co., Ltd., acicular titanium oxide whose surface is coated with tin oxide / antimony.

(Note 11) Metal oxide-coated scaly mica: “Iriodin 103R” (trade name, manufactured by Merck & Co., Inc. The surface of scaly mica is coated with SnO ₂ as the lower layer, and the coated surface is coated with TiO ₂ as the upper layer. A non-conductive filler having an average particle size of 22 μm.

The white conductive primer paint No. 1 of the present invention obtained in coating test examples 1-5. 1-No. 5 and comparative white conductive primer paint No. 1 obtained in Comparative Examples 1 to 4. 6-No. For No. 9, a multilayer coating film was formed according to the following painting steps 1, 2, and 3, and the coating film performance was examined.

Coating process 1: Coating of white conductive primer coating As a plastic base material, black polypropylene is molded into a bumper shape and then degreased. 1 to 11 were air spray coated so that the dry film thickness was 20 μm. This coated film was left to set at room temperature for 1 minute, preheated at 80 ° C. for 3 minutes, and then heated and cured at 120 ° C. for 20 minutes. The coating film was evaluated for L ^* value and surface electrical resistance value A described later.

Coating step 2: Multi-layer coating formation coating with water-based base coating and organic solvent-type clear coating on white conductive primer coating. Water-based thermosetting transparent coloring on the cured coating obtained in coating step 1. A paint (trade name “WBC-710 Mica Base”, manufactured by Kansai Paint Co., Ltd.) is electrostatically applied to a cured film thickness of 15 to 20 μm, preheated at 80 ° C. for 3 minutes, and then surface electrical resistance described later After confirming the value B, an organic solvent-type acrylic resin / urethane resin-based thermosetting clear paint (trade name “SOFLEX # 520 Clear”, manufactured by Kansai Paint Co., Ltd.) is applied on the uncured transparent colored coating film. Electrostatically coated to a cured film thickness of 25 μm, left at room temperature for 5 minutes, then heated at 120 ° C. for 30 minutes to simultaneously cure the colored coating and clear coating to form a multilayer coating Formed.

Coating process 3: Multi-layer coating film coating with organic solvent-type base paint and organic solvent-type clear paint on white conductive primer coating film Organic solvent-type heat on the cured coating film obtained in coating process 1 After electrostatically coating a curable transparent coloring paint (trade name “SOFLEX # 420 Mica Base”, manufactured by Kansai Paint Co., Ltd.) so that the cured film thickness is 15 to 20 μm, and preheating at 80 ° C. for 3 minutes. After confirming the surface electrical resistance value C described later, an organic solvent-type acrylic resin / urethane resin thermosetting clear paint (trade name “SOFLEX # 520 clear”, Kansai Paint ( Co., Ltd.) was applied electrostatically so that the cured film thickness was 25 μm, and allowed to stand at room temperature for 5 minutes, then heated at 120 ° C. for 30 minutes to simultaneously cure the colored coating and clear coating, A multilayer coating was formed.

The L ^* value, surface electrical resistance value A, surface electrical resistance value B, and surface electrical resistance value C were examined by the following test method.

L ^* value: After the white conductive primer coating film was heat-cured at 120 ° C. for 20 minutes, L ^* a ^* defined in JIS Z 8729 using “Color Computer SM-7” manufactured by Suga Test Instruments Co., Ltd. L ^* values based on the b ^* color system were measured.

Surface electrical resistance value A: A white conductive primer coating was applied, and the surface electrical resistance value of the coating film after heat curing was measured with an electrical resistance measuring device (trade name “MODEL150” manufactured by TREK). If the measured value is less than 10 ⁹ Ω / □, the top coating can be electrostatically coated.

Surface electrical resistance value B: Painted with white conductive primer paint, preheated at 80 ° C. for 3 minutes, then painted with transparent colored paint “WBC-710 mica base” and preheated at 80 ° C. for 3 minutes. The surface electrical resistance value of the film was measured with an electrical resistance measuring device (trade name “MODEL150” manufactured by TREK). The solvent of the transparent coloring paint swells the aqueous white primer coating and increases the surface electrical resistance value, which may make the clear paint impossible to electrostatically paint. However, the electrical resistance value is 10 ⁹ Ω / If it is less than □, clear paint can be electrostatically coated.

Surface electrical resistance value C: A white conductive primer paint is applied, preheated at 80 ° C. for 3 minutes, and then a transparent colored paint “SOFLEX # 420 Mica Base” is applied, and the surface electrical resistance of the primer coating after 1 minute The resistance value was measured with an electric resistance measuring device (trade name “MODEL150” manufactured by TREK). The solvent of the transparent coloring paint swells the aqueous white primer coating and increases the surface electrical resistance value, which may make the clear paint impossible to electrostatically paint. However, the electrical resistance value is 10 ⁹ Ω / If it is less than □, clear paint can be electrostatically coated.

  The test results of the inventive white conductive primer coatings of Examples 1 to 5 are shown in Table 3, and the test results of the comparative white conductive primer coatings of Comparative Examples 1 to 4 are shown in Table 4, respectively.

表３において、実施例５の白色導電性プライマー塗料Ｎｏ．５の表面電気抵抗値Ｃは、プライマー塗料塗装後、予備加熱に代えて１分間セッティングし、その後「ソフレックス＃４２０マイカベース」を塗装し、１分後の該プライマー塗膜の表面電気抵抗値を示す。

In Table 3, the white conductive primer coating no. The surface electrical resistance value C of 5 is set for 1 minute instead of preheating after the primer coating, and after that, “Soflex # 420 Mica Base” is applied, and the surface electrical resistance value of the primer coating after 1 minute. Indicates.

表４において、比較例６の白色導電性プライマー塗料Ｎｏ．１１の表面電気抵抗値Ｃは、プライマー塗料塗装後、予備加熱に代えて１分間セッティングし、その後「ソフレックス＃４２０マイカベース」を塗装し、１分後の該プライマー塗膜の表面電気抵抗値を示す。

In Table 4, the white conductive primer coating no. The surface electrical resistance value C of 11 was set for 1 minute after the primer coating, instead of preheating, and after that, “Soflex # 420 Mica Base” was applied and the surface electrical resistance value of the primer coating after 1 minute. Indicates.

In the coating step 2 of the coating test, the comparative white conductive primer paint No. 8 and no. For No. 9, since the surface electrical resistance value of the primer coating was as high as 10 ⁹ Ω / □ or more, the colored paint and the clear paint could not be electrostatically applied.

In the painting process 3 of the painting test, the white conductive primer paint No. 1 for comparison was used. 8 and no. For No. 9, since the surface electrical resistance value of the primer coating was as high as 10 ⁹ Ω / □ or more, the colored paint and the clear paint could not be electrostatically applied.

  About each multilayer coating film obtained according to the said coating process 1 and 2 using each white conductive primer coating material of Examples 1-5 and Comparative Examples 1 and 2, it is prescribed | regulated to coating-film external appearance, JISZ8721. N value based on Munsell color system, adhesion and water resistance coating performance and recyclability tests were examined by the following test methods.

  Appearance of coating film: In the vertical part of the base material, the presence or absence of abnormality such as sagging, returning, swelling, etc. of the coating film was visually evaluated according to the following criteria.

  ○ indicates that the above abnormality is not recognized at all, Δ indicates that at least one abnormality of sagging, returning, and blistering is observed, and x indicates that abnormalities such as sagging, returning, and blistering are remarkable.

  N value based on Munsell color system defined in JIS Z 8721: N value of Munsell chart was determined for a multi-layer coating consisting of three layers: a white primer coating, a transparent coloring coating, and a clear coating. 0 is black and 10 is pure white.

  Adhesiveness: In a multi-layer coating consisting of three layers: a white conductive primer coating, a transparent coloring coating, and a clear coating, cut with a cutter to reach the substrate, make 100 2mm wide gobangs, The adhesive tape was adhered to the surface, and the remaining number in 100 Gobanchi coatings after peeling off rapidly at 20 ° C. was examined and evaluated according to the following criteria.

  ○ indicates all adherence remains and has good adhesion, △ indicates adherence with 90 to 99 remaining, and × indicates less than 90 remaining and poor adhesion. , Respectively.

  Water resistance: In a multi-layer coating consisting of three layers, a white conductive primer coating, a transparent colored coating, and a clear coating, after being immersed in warm water at 40 ° C. for 240 hours, cut with a cutter to reach the substrate, 2 mm 100 gobangs having a width were made, and an adhesive tape was adhered to the surface, and the number of remaining in 100 gobain coatings after abrupt peeling at 20 ° C. was examined and evaluated according to the following criteria.

  ○ indicates that all of the Gobanges remain and has good water resistance, △ indicates that the remaining number of Gobanges is 90 to 99, indicating poor water resistance, and × indicates that the remaining number of Gobanges is less than 90 and indicates poor water resistance. , Respectively.

  Recyclability: The substrate having a multi-layer coating composed of three layers of white conductive primer coating, colored base coating, and clear coating is pulverized into a powder of about 1 mm or less by a pulverizer, and then the pulverized product is examined with an optical microscope. Observed. Among the acicular fillers contained in the pulverized product, those having an aspect ratio of 3 or more are defined as whiskers, and are said to have a great influence on the human body during recycling. The evaluation criteria for recyclability are as follows.

○: The filler contained in the pulverized product has a scale shape or a spherical shape, and is excellent in the recyclability of the coated plastic substrate.
X: The whisker of aspect ratio 3 or more is contained in the acicular filler contained in the pulverized product, and the recyclability of the coated plastic substrate is inferior.

  The results of the performance test of the multilayer coating film are shown in Table 5.

実施例１〜５及び比較例１、２の各白色導電性プライマー塗料を用いて、上記塗装工程１及び３に従って得られた各複層塗膜について、塗膜外観、ＪＩＳ Ｚ ８７２１に規定されるマンセル表色系に基づくＮ値、付着性及び耐水性の塗膜性能及びリサイクル性の試験を、前記試験方法により調べた。

About each multilayer coating film obtained according to the said coating processes 1 and 3 using each white electroconductive primer coating material of Examples 1-5 and Comparative Examples 1 and 2, it is prescribed | regulated to coating-film external appearance and JISZ8721. The N value, adhesion and water-resistant coating film performance based on the Munsell color system, and the test of recyclability were examined by the test method.

  Table 6 shows the results of the performance test of the multilayer coating film.

Claims (9)

(A) 100 parts by weight of a resin component containing a chlorinated polyolefin resin having a chlorination rate of 10 to 35% by weight,
(B) Tin oxide, antimony-doped tin oxide (ATO), tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), phosphorus-doped tin oxide, zinc antimonate, indium-doped zinc oxide, ruthenium oxide, rhenium oxide, oxidation 1 to 150 parts by weight of pigment coated on the surface of mica with at least one conductive metal oxide selected from the group consisting of silver, nickel oxide and copper oxide; and (c) tin oxide and phosphorus on the surface of titanium dioxide particles. White conductive titanium dioxide powder 1 to 1 having a conductive layer containing 1 and a content of a metal element having a valence of 3 or less as an impurity is 0.1 or less as (A) determined by the following formula (1) 150 parts by weight of white conductive primer paint,
Formula (1): (A) = (M ₁ ) × (4-n ₁ ) + (M ₂ ) × (4-n ₂ ) + (M ₃ ) × (4-n ₃ ) + (M ₄ ) × (4-n ₄ ) +... + (M _X ) × (4-n _X )
(Here, M ₁ , M ₂ , M ₃ , M ₄ ,..., M _X are the atomic ratios of metal elements having a valence of 3 or less to Sn of tin oxide in the white conductive titanium dioxide powder, _{n 1, n 2, n 3} , n 4, ..., n X _{is, M 1, M 2, M} 3, M 4, ..., indicate the respective valences of metal elements having atomic ratios of M _X, M _{X of X} and n _X represents the number of the metal elements contained in the white conductive titanium dioxide powder and can take a natural number of 1 or more.) 2. The coating amount of tin oxide forming a conductive layer in the white conductive titanium dioxide powder (c) is in a range of 0.03 to 0.3 g as SnO ₂ per 1 m ^{2 of} titanium dioxide surface area. White conductive primer paint. The content of phosphorus contained in the conductive layer in the white conductive titanium dioxide powder (c) is a ratio of 0.10 to 0.50 in terms of P / Sn atomic ratio with respect to tin oxide. White conductive primer paint. In the white conductive titanium dioxide powder (c), the content of a metal element having a valence of 3 or less as an impurity contained in titanium dioxide is 0.02 or less as (B) determined by the following formula (2): The white conductive primer paint according to 1,
Formula (2): (B) = (M ′ ₁ ) × (4-n ′ ₁ ) + (M ′ ₂ ) × (4-n ′ ₂ ) + (M ′ ₃ ) × (4-n ′ ₃ ) + (M ′ ₄ ) × (4-n ′ ₄ ) +... + (M ′ _Y ) × (4-n ′ _Y )
(Here, M ′ ₁ , M ′ ₂ , M ′ ₃ , M ′ ₄ ,..., M ′ _Y are atomic ratios of metal elements having a valence of 3 or less with respect to Ti of titanium dioxide, and n ′ _{1 , n'2, n'3, n'} 4, ..., n'Y _{is, M'1, M'2, M'} 3, M'4, ..., each of the metal elements having atomic ratios of _M'Y And _Y of M ′ _Y and n ′ Y represents the number of the metal elements contained in titanium dioxide, and can take a natural number of 1 or more). Furthermore, (d) The white electroconductive primer coating material of any one of Claims 1-4 containing 200 weight part or less of white pigments. The coating film obtained by coating on a plastic substrate and drying or curing is a coating film having a brightness (L ^* value) of 80 or more based on the L ^* a ^* b ^* color system defined in JIS Z 8729. The white electroconductive primer coating material of any one of Claims 1-5. The white conductive primer paint according to any one of claims 1 to 6, wherein a surface electric resistance value of a coating film obtained by coating on a plastic substrate and drying or curing is less than 10 ⁹ Ω / □. (1) Applying the white conductive primer paint according to claim 1 to a plastic substrate so that the dry film thickness is about 10 to 45 μm, and setting or preheating,
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat one-bake in which the three-layer coating film comprising the primer paint, the colored base paint and the clear paint is simultaneously heated and baked. (1) Applying the white conductive primer paint according to claim 1 to a plastic substrate so that the dry film thickness is about 10 to 45 μm, and heat-curing,
(2) a process of electrostatically painting the colored base paint so that the dry film thickness is about 5 to 30 μm;
(3) A process of electrostatically coating the clear paint so that the dry film thickness is about 10 to 40 μm, then
(4) A method for forming a multilayer coating film by three-coat two-baking, in which the two-layer coating film comprising the above colored base coating and clear coating is simultaneously heated and baked.