Conductive primer coating composition, method for producing same, coating film using same, and method for forming multilayer coating film

Abstract

The present invention addresses the problem of providing: a conductive primer coating composition which can impart excellent electrical conductivity to a plastic substrate material when it contains a solvent immediately after coating, and which can be used for forming a multi-layer coating film; a method for producing the same; a coating film using the same; and a method for forming a multi-layer coating film. And good adhesive force is achieved between different types of plastic base materials and finish paint films under the condition of low-temperature and short-time heating. The solution uses a conductive primer coating composition, a method for producing the same, a primer coating film formed from these conductive primer coating compositions, and a method for forming a multilayer coating film, these conductive primer coating compositions comprise (C) a conductive pigment paste made by dispersing (A) a conductive pigment in (B) a non-chlorinated polyolefin resin comprising a hydroxyl group, (D) an acrylic resin-modified chlorinated polyolefin resin, and (E) a blocked polyisocyanate compound.

Description

TECHNICAL FIELD

[0001] The present application relates to an electroconductive primer coating composition, a production method thereof, a coated film using the same, and a method for forming a multilayer coated film. BACKGROUND

[0002] In order to electrostatically coat a top coat on a plastic base material, it is known technology to use an electroconductive primer coating composition as a base paint intended to impart electroconductivity, and it is also widely known that electroconductive pigments exist as an agent for imparting electroconductivity.

[0003] In recent years, in order to improve productivity, it is desirable that such an electroconductive primer coating composition directly imparts excellent electroconductivity to a plastic base material even while still containing a solvent after coating. Therefore, if after coating an electroconductive primer, the base material can be subjected to electrostatic coating in the next process without waiting for complete drying, it is possible to shorten the production line from primer coating to top coat coating, it is possible to save production time, and it is possible to improve productivity. Therefore, it is industrially advantageous to manufacture an electroconductive primer coating composition that is electroconductive immediately after coating.

[0004] Furthermore, from the viewpoint of reducing energy use, it is desirable that these electroconductive primer coating compositions exhibit good adhesion between different types of plastic base materials and top coat films with short-time heating at low temperatures.

[0005] For example, from the viewpoint of being electroconductive immediately after coating, Patent Literature 1 discloses an electroconductive primer coating composition comprising (A) a chlorinated polyolefin resin not containing a hydroxyl group, or a chlorinated polyolefin resin not containing a hydroxyl group and a non-chlorinated polyolefin resin not containing a hydroxyl group, (B) a blocked polyisocyanate, and (C) an electroconductive carbon, characterized in that the mass ratio of A / B of the solids is 50 / 50-90 / 10, and in 100 parts by mass of the resin solids, (C) is 3-30 parts by mass; and it is claimed that these coating compositions can impart electroconductivity to a plastic base material immediately after coating, and can also give good adhesion.

[0006] Furthermore, in relation to achieving low-temperature curing conditions, Patent Literature 2 discloses a coating composition containing a specified acrylic resin (A), a polyolefin resin which can be chlorinated (B), and also a pyrazole-terminated polyisocyanate compound and / or an active-methylene-terminated polyisocyanate compound (C), wherein of the total solids of 100 parts by mass of components (A), component (B) and component (C), component (A) is 10-50 parts by mass, component (B) is 20-60 parts by mass, and component (C) is 5-30 parts by mass. According to this document, it is claimed that electrical conductivity can be imparted by these coating compositions, and that they can form a coating film having good adhesion and water resistance under low-temperature curing conditions. Furthermore, Patent Literature 3 discloses a coating composition comprising a chlorinated and / or non-chlorinated polyolefin (A), an acrylic-modified styrene-based thermoplastic elastomer (B), an epoxy resin (C), a capped polyisocyanate compound (D) and a pigment (E), and it is claimed that using these coating compositions, it is possible to form a coating film having excellent shatter resistance, adhesion and gasoline resistance on both metal materials and plastic materials. Prior Art Documents

[0007] [Patent Literature]

[0008] [Patent Literature 1] JP 4400292 B2

[0009] [Patent Literature 2] JP 2012-193320 A

[0010] [Patent Literature 3] JP 2019-167390 A SUMMARY

[0011] Problems to be Solved by the Invention

[0012] However, in the case of the coating composition in Patent Literature 1, although the plastic material is imparted with a certain degree of electrical conductivity immediately after coating, it is necessary to heat at 120°C for 20 minutes to harden the coating composition. Furthermore, in the case of the coating compositions in Patent Literatures 2 and 3, electrical conductivity is not obtained immediately after coating. Furthermore, the curing temperature of these coating compositions needs to be, for example, 95°C for 30 minutes (Patent Literature 2) and 80°C for 30 minutes (Patent Literature 3); thus, from the viewpoint of treating environmental problems, it is desirable to cure at a lower temperature for a shorter time.

[0013] Thus, the problem to be solved by the present application is to provide electrically conductive primer coating compositions which can impart excellent electrical conductivity to a plastic base material immediately after coating while it still contains a solvent, and have good adhesion between different types of plastic base materials and top coat films under the condition of short-time heating at a low temperature, a production method thereof, a primer coating film formed from the electrically conductive primer coating compositions, and a method for forming a multilayer coating film.

[0014] Means for solving the problem

[0015] As a result of intensive research to solve the above problem, the present inventors have perfected the present application by the following discovery, wherein the problem can be solved by electrically conductive primer coating compositions comprising (C) an electrically conductive pigment paste comprising (A) an electrically conductive pigment dispersed in (B) a non-chlorinated polyolefin resin containing a hydroxyl group, and (D) an acrylic resin-modified chlorinated polyolefin resin and (E) a blocked polyisocyanate compound.

[0016] Further, in the electrically conductive primer coating compositions of the present application, the mass ratio of the resin solids of (B) the non-chlorinated polyolefin resin containing a hydroxyl group and (D) the acrylic resin-modified chlorinated polyolefin resin is preferably 10 / 90 to 60 / 40.

[0017] Further, in the electrically conductive primer coating compositions of the present application, the sum of the resin solids of (B) the non-chlorinated polyolefin resin containing a hydroxyl group and (D) the acrylic resin-modified chlorinated polyolefin resin is preferably 10 mass parts or more in 100 mass parts of the total resin solids in the electrically conductive primer coating compositions.

[0018] Further, in the electrically conductive primer coating compositions of the present application, (B) the non-chlorinated polyolefin resin containing a hydroxyl group preferably has a hydroxyl value of 15 to 90 mgKOH / g.

[0019] Further, in the electrically conductive primer coating compositions of the present application, (D) the acrylic resin-modified chlorinated polyolefin resin preferably has a mass average molecular weight of 20,000 to 150,000.

[0020] Further, in the electrically conductive primer coating compositions of the present application, (E) the blocked polyisocyanate compound is preferably an active-methylene-blocked polyisocyanate compound.

[0021] Further, in the electrically conductive primer coating compositions of the present application, (A) the electrically conductive pigment preferably includes a black electrically conductive pigment and / or a white electrically conductive pigment.

[0022] Further, the above problems solved by the present application are also solved by a method for producing an electroconductive primer coating composition, the method being characterized by manufacturing (C) an electroconductive pigment paste by dispersing (A) an electroconductive pigment in (B) a non-chlorinated polyolefin resin containing a hydroxyl group,

[0023] and then mixing (C) the electroconductive pigment paste, (D) an acrylic resin-modified chlorinated polyolefin resin, and (E) a blocked polyisocyanate compound.

[0024] The problems solved by the present application are also solved by primer coating films, which are dried coating films of the above electroconductive primer coating composition.

[0025] The primer coating films of the present application on a plastic base material preferably have a lightness L value of 20 to 70 in the CIE LAB color system.

[0026] Further, the primer coating films of the present application preferably have a dry film thickness of 2 to 20 µm.

[0027] The problems solved by the present application are also solved by a method for forming a multilayer coating film, the method being characterized by

[0028] a step (1) of applying the above electroconductive primer coating composition to a plastic base material and forming an electroconductive coating film,

[0029] a step (2) of applying a basecoat coating composition to the electroconductive coating film obtained in the above step (1) to obtain a basecoat coating film,

[0030] The problems solved by the present application are also solved by a method for forming a multilayer coating film, the method being characterized by

[0031] a step (1) of applying the above electroconductive primer coating composition to a plastic base material and forming an electroconductive coating film,

[0032] a step (2) of applying a basecoat coating composition to the electroconductive coating film obtained in the above step (1) to obtain a basecoat coating film,

[0033] a step (3) of applying a clearcoat coating composition to the basecoat coating film obtained in the step (2) and curing. Effects of the Invention

[0034] With the conductive primer coating composition of the present application, it is possible to impart excellent conductivity to a plastic substrate material immediately after coating when it contains a solvent, and it is possible to give good adhesion between different types of plastic substrate materials and top coat films with short time heating at low temperature. Thus, the resulting multilayer coating film shows excellent water adhesion resistance between the plastic substrate material and the top coat film thereon. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram explaining a method for measuring the surface resistance of uncured primer coating films in the examples and comparative examples of the present application. DETAILED DESCRIPTION

[0036] The conductive primer coating composition of the present application comprises (C) a conductive pigment paste produced by dispersing (A) a conductive pigment in (B) a non-chlorinated polyolefin resin containing a hydroxyl group, and

[0037] (D) an acrylic resin-modified chlorinated polyolefin resin, and

[0038] (E) a blocked polyisocyanate compound.

[0039] Among these materials, the (C) conductive pigment paste comprises (A) a conductive pigment and (B) a non-chlorinated polyolefin resin containing a hydroxyl group as essential ingredients.

[0040] There is no particular limitation on the (A) conductive pigment employed in the present application, provided that it can impart conductivity to the coating film formed, and it can take any form, such as particles, flakes or fibers (including whiskers) and the like. There is no particular limitation on the color of the (A) conductive pigment employed in the present application, provided that it can impart conductivity to the coating film, but preferred conductive pigments are black conductive pigments and / or white conductive pigments.

[0041] The black conductive pigment used in the present application includes conductive carbon black, carbon nanotube, graphite, and carbon fiber; among these black conductive pigments, conductive carbon black is preferred. Commercially available conductive carbon black includes Mitsubishi conductive carbon black #3030B, #3050B, #3230B, and #3400B (proprietary name, produced by Mitsubishi Chemical Corp.), Ketjenblack EC300J and EC600JD (proprietary name, produced by Lion Specialty Chemicals Co., Ltd.), VULCAN XC72 and XC605 (proprietary name, produced by Cabot Corp.), Chezacarb AC10, AC20, AC30, AC50, AC60, AC70, AC80, and AC90 (proprietary name, produced by Orlen Unipetrol), Denka Black (proprietary name, produced by Denka Co., Ltd.), and the like. These black conductive pigments can be used alone or in combination of two or more kinds.

[0042] The white conductive pigment used in the present application includes a titanium oxide product on which tin oxide or tin antimony oxide is coated on the surface, or a potassium titanate fiber-derived product on which a transparent conductive layer is coated on the surface. Commercially available white conductive pigments include white conductive powder W-1 and W-4 (proprietary name, produced by Mitsubishi Materials Electronic Chemicals Co., Ltd.) as a powder type, white conductive material ET-300W and ET-500W (proprietary name, produced by Ishihara Sangyo Kaisha, Ltd.) and the like; white conductive material FT-1000, FT-2000, FT-3000, and FT-4000 (proprietary name, produced by Ishihara Sangyo Kaisha, Ltd.), and Dentall WK-200B, WK-500, WK-500B (proprietary name, produced by Otsuka Chemical Co., Ltd.) and the like as a fiber type. These white conductive pigments can be used alone or in combination of two or more kinds.

[0043] The (B) non-chlorinated polyolefin resin containing a hydroxyl group used in the present application is not particularly limited; examples include a polyolefin resin obtained by a known method using a monomer selected from the group consisting of C 2-10One or two or more kinds of olefins such as ethylene, propylene, butylene, methylbutene, hexene, butadiene, isoprene, and the like, and one or two or more kinds selected from among hydroxyl group-containing ethylenically unsaturated monomers including (meth)acrylates having a hydroxyl group such as hydroxyethyl (meth)acrylate, unsaturated alcohols such as allyl alcohol, vinyl ethers having a hydroxyl group such as hydroxyethyl vinyl ether, and the like, as essential components are copolymerized or graft-polymerized.

[0044] The (B) non-chlorinated polyolefin resin containing a hydroxyl group employed in the present application preferably has a hydroxyl value of 15 to 90 mgKOH / g; 20 to 85 mgKOH / g is more preferable, and 25 to 80 mgKOH / g is particularly preferable. By making the (B) non-chlorinated polyolefin resin containing a hydroxyl group have a hydroxyl value of 15 to 90 mgKOH / g, it is possible to impart an excellent water resistance of the resulting multilayer film.

[0045] In the present application, the hydroxyl value is a value measured according to JIS-K 1557.

[0046] The (B) non-chlorinated polyolefin resin containing a hydroxyl group employed in the present application preferably has a mass average molecular weight of 4,500 to 100,000; 4,700 to 95,000 is more preferable, and 4,800 to 90,000 is particularly preferable. By making the (B) non-chlorinated polyolefin resin containing a hydroxyl group have a mass average molecular weight of 4,500 to 100,000, it is possible to impart an excellent electrical conductivity to a plastic base material when it contains a solvent immediately after coating.

[0047] In the present application, the mass average molecular weight is a mass average molecular weight measured by gel permeation chromatography (GPC). The measurement is performed using tetrahydrofuran (THF) as an eluent at a temperature of 40°C and a flow rate of 1 ml / min, with a polystyrene standard. The gel permeation chromatography (GPC) column used is TSKgel G2000HXL, G3000HXL, G4000HXL, and G5000HXL (proprietary name, manufactured by Tosoh Corp.).

[0048] The commercially available (B) non-chlorinated polyolefin resin containing a hydroxyl group includes, for example, Polytail H (a proprietary name, produced by Mitsubishi Chemical Corporation), Unistole P-801 and P-901 (proprietary names, produced by Mitsui Chemicals Inc.), NISSO-PB-G-1000, NISSO-PB-G-2000, NISSO-PB-G-3000, NISSO-PB-GI-1000, NISSO-PB-GI-2000, and NISSO-PB-GI-3000 (proprietary names, produced by Nippon Soda Co., Ltd.), and the like.

[0049] In the (C) electrically conductive pigment paste employed in the present application, the solid ratio (mass ratio) of the (A) electrically conductive pigment and the (B) non-chlorinated polyolefin resin containing a hydroxyl group is preferably 10 / 90 to 96 / 4; 12 / 88 to 94 / 6 is more preferable, and 14 / 86 to 92 / 8 is particularly preferable. By making the solid ratio of the (A) electrically conductive pigment and the (B) non-chlorinated polyolefin resin containing a hydroxyl group 10 / 90 to 96 / 4, the (A) electrically conductive pigment forms relatively large aggregates (also referred to as structures) in the (C) electrically conductive pigment paste. And when a conductive primer coating composition containing this (C) electrically conductive pigment paste is applied, the aggregates of the (A) electrically conductive pigment immediately form a three-dimensional structure in the coating film formed on a plastic base material. Thus, although the conductive primer coating composition has not yet completely dried and still contains a solvent, it can impart excellent electrical conductivity to the plastic base material immediately after application.

[0050] It should be noted that, in the present application, "immediately after application" means within about 30 seconds at room temperature (25°C) and atmospheric pressure, although it will also depend on the application environment. Furthermore, "it still contains a solvent" means a state before the quality of the primer coating film of the conductive primer coating composition reaches that after curing.

[0051] Optionally, an organic solvent, a resin, and a non-conductive pigment can also be suitably contained in the (C) electrically conductive pigment paste employed in the present application. However, it is preferable not to include a pigment dispersant or the like that can hinder the formation of aggregates of the (A) electrically conductive pigment.

[0052] Examples of organic solvents include aromatic hydrocarbons such as toluene, xylene, and aromatic naphtha (Solvesso #100 (proprietary name) etc.); alcohols such as methanol, isopropanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, and methyl pentyl ketone; esters such as ethyl acetate, n-butyl acetate, 2-butoxyethyl acetate, amyl acetate, and ethyl ethoxypropionate; ethers; and aliphatic hydrocarbons, including chlorinated hydrocarbons. These organic solvents can be used alone or in combination of two or more.

[0053] In addition, examples of resins include acrylic resins, polyester resins, epoxy resins, chlorinated polyolefin resins, etc. These resins can be used alone or in combination of two or more.

[0054] It should be noted that resins that do not contain functional groups such as amino or imino groups that prevent the formation of aggregates of (A) conductive pigments are preferred.

[0055] In addition, non-conductive pigments include, for example, colored pigments, including inorganic pigments such as titanium dioxide pigments, iron oxide pigments, and composite oxide pigments including titanium yellow, and organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, violet ketone pigments, benzimidazolone pigments, isoindoline pigments, isoindolineone pigments, azo metal chelate pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, thiophene pigments, indigo pigments, etc.; as well as extender pigments such as calcium carbonate, barium sulfate, aluminum hydroxide, talc, and silicon dioxide. These non-conductive pigments can be used alone or in combination of two or more.

[0056] In addition to (C) the conductive pigment paste, the conductive primer coating composition of the present invention also includes (D) an acrylic resin-modified chlorinated polyolefin resin and (E) a capped polyisocyanate compound.

[0057] There are no particular limitations on the (D) acrylic resin-modified chlorinated polyolefin resin used in this invention; examples include the use of C by known methods. 2-10 Chlorinated products of copolymerization or graft polymerization of one or more olefins such as ethylene, propylene, butene, methylbutene, hexene, butadiene, and isoprene with one or more acrylic monomers such as (meth)acrylic acid and (meth)acrylates as basic components. It should be noted that during copolymerization or graft polymerization, olefinic unsaturated monomers such as maleic acid, maleic anhydride, fumaric acid, styrene, acrylonitrile, and vinyl acetate can also be included as other monomers.

[0058] The mass average molecular weight of the (D) acrylic resin-modified chlorinated polyolefin resin used in the present application is preferably 20,000 to 150,000; 22,000 to 140,000 is more preferable, and 25,000 to 130,000 is particularly preferable. By making the mass average molecular weight of the (D) acrylic resin-modified chlorinated polyolefin resin 20,000 to 150,000, it is possible to impart excellent water resistance of the multilayer coating film.

[0059] The hydroxyl value of the (D) acrylic resin-modified chlorinated polyolefin resin used in the present application is preferably 2 to 70 mgKOH / g; 4 to 65 mgKOH / g is more preferable, and 5 to 60 mgKOH / g is particularly preferable. By making the hydroxyl value of the (D) acrylic resin-modified chlorinated polyolefin resin 2 to 70 mgKOH / g, it is possible to impart excellent water resistance of the multilayer coating film.

[0060] The chlorine content of the (D) acrylic resin-modified chlorinated polyolefin resin used in the present application is preferably 0.1 mass% to 55 mass%; 0.5 mass% to 45 mass% is more preferable, and 1 mass% to 35 mass% is particularly preferable. By making the chlorine content of the (D) acrylic resin-modified chlorinated polyolefin resin 0.1 mass% to 55 mass%, it is possible to impart excellent water resistance of the multilayer coating film.

[0061] Commercially available (D) acrylic resin-modified chlorinated polyolefin resins include, for example, Superchlon 224H, 223M, and 240H (proprietary name, produced by Nippon Paper Industries Co., Ltd.), ACRYDIC WFL-367, WML-350, CL-408, and CL-1000 (proprietary name, produced by DIC Corporation), and the like.

[0062] The resin solid ratio of the above (B) non-chlorinated polyolefin resin containing a hydroxyl group and (D) acrylic resin-modified chlorinated polyolefin resin in the conductive primer coating composition of the present application is preferably 10 / 90 to 60 / 40; 15 / 85 to 55 / 45 is more preferable, and 20 / 80 to 50 / 50 is particularly preferable. By making the resin solid ratio of the (B) non-chlorinated polyolefin resin containing a hydroxyl group and (D) acrylic resin-modified chlorinated polyolefin resin 10 / 90 to 60 / 40, it is possible to impart excellent conductivity on a plastic base material immediately after coating when it contains a solvent, and it is possible to impart excellent water resistance of the multilayer coating film.

[0063] The total amount of resin solids (B) comprising a hydroxyl-containing non-chlorinated polyolefin resin and (D) an acrylic resin-modified chlorinated polyolefin resin in 100 parts by weight of the conductive primer coating composition is preferably 10 parts by weight or more; 15-95 parts by weight is more preferred, and 20-90 parts by weight is particularly preferred. By ensuring that the total amount of resin solids (B) comprising a hydroxyl-containing non-chlorinated polyolefin resin and (D) an acrylic resin-modified chlorinated polyolefin resin in 100 parts by weight of the conductive primer coating composition is 10 parts by weight or more, it is possible to impart excellent water resistance and adhesion to multilayer coatings.

[0064] There are no particular limitations on the isocyanate compounds used in the (E)-terminated polyisocyanate compounds employed in this invention, provided that they are suitable for coating applications; and various types of polyisocyanate compounds can be used. For example, various types of polyisocyanate compounds can be used, such as aromatic polyisocyanate compounds and aliphatic or alicyclic polyisocyanate compounds. Suitable polyisocyanate compounds include, for example, toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), 2-ethyl-2,6-diisocyanate hexanoate (LTI), isophorone diisocyanate (IPDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), hydrogenated TDI, hydrogenated MDI, hydrogenated XDI, etc. In addition, it includes structures using these polyisocyanate compounds such as urea diketone, urethane, adduct, biuret, isocyanurate, and iminooxadiazine diketone. These polyisocyanate compounds can be used alone or in combination of two or more.

[0065] (E) The terminated polyisocyanate compounds include the above-mentioned polyisocyanate compounds, wherein the isocyanate group is terminated by compounds including, for example, alcohols such as butanol, oximes such as butyl ethyl ketone oxime, lactams such as ε-caprolactam derivatives, active methylene compounds such as malonate and acetoacetate, pyrazoles such as 3,5-dimethylpyrazole, imidazoles such as imidazole and 2-ethylimidazol, phenols such as m-cresol, etc.

[0066] Among the above active methylene compounds, malonic acid diesters include dimethyl malonate, diethyl malonate, diisopropyl malonate, n-propyl malonate, n-butyl malonate, ethyl n-butyl malonate, methyl n-butyl malonate, ethyl t-butyl malonate, methyl t-butyl malonate, dibenzyl malonate, diphenyl malonate, benzyl methyl malonate, ethyl phenyl malonate, t-butyl phenyl malonate, and the like. In addition, acetoacetic acid esters include methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, n-propyl acetoacetate, t-butyl acetoacetate, n-butyl acetoacetate, benzyl acetoacetate, phenyl acetoacetate, and the like. These active methylene compounds can be used alone or in combination of two or more kinds.

[0067] As the (E) blocked polyisocyanate compound employed in the present application, an active-methylene-blocked polyisocyanate compound is more preferable, and a malonic acid diester-blocked polyisocyanate compound is particularly preferable.

[0068] The conductive primer coating composition of the present application can further contain an epoxy resin. The epoxy resin used in the present application is not particularly limited, provided that it has at least two epoxy groups per molecule, and a known epoxy resin can be used. Examples include bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolak type epoxy resins, cresol novolak type epoxy resins, naphthalene type epoxy resins, biphenyl type epoxy resins, cyclopentadiene type epoxy resins, and the like, and a product having an epoxy equivalent weight of 150 to 250 and being liquid at room temperature (25°C) is preferable. These epoxy resins can be used alone or in combination of two or more kinds.

[0069] Commercially available epoxy resins having an epoxy equivalent weight of 150 to 250 and being liquid at room temperature (25°C) include, for example, jER825, jER827, jER828, jER828EL, jER828US, and jER828XA (proprietary names, produced by Mitsubishi Chemical Corporation), YD-115, YD-115CA, YD-127, YD-128, YD-128G, YD-128S, YD-128CA, YD-8125, YD-825GS, YDF-170, YDF-170N, YDF-8170C, YDF-870GS, and ST-3000 (proprietary names, produced by NIPPON STEEL Chemical & Material Co., Ltd.), and the like.

[0070] Optionally, the conductive primer coating composition of the present application can further include a resin such as a polyester resin, a polyurethane resin, an acrylic resin, a phenol resin, a polyether resin, a non-chlorinated polyolefin resin not containing a hydroxyl group, or the like. In addition, additives conventionally employed in the field of coating such as a curing catalyst, an anti-sagging agent, an anti-cratering agent, and the like can be appropriately used. However, it is preferable not to include a pigment dispersant or the like that can hinder the formation of aggregates of (A) the conductive pigment.

[0071] The content of (A) the conductive pigment included in the conductive primer composition of the present application is preferably 3 to 115 parts by mass, more preferably 4 to 105 parts by mass, and particularly preferably 5 to 95 parts by mass, based on 100 parts by mass of the total resin solids in the conductive primer coating composition. By having the content of (A) the conductive pigment be 3 to 115 parts by mass, it is possible to impart excellent electrical conductivity to a plastic base material immediately after coating when it contains a solvent.

[0072] In addition, the conductive primer coating composition of the present application can be adjusted to a viscosity that is conducive to production by using an organic solvent. The organic solvent includes organic solvents that are generally used in the production of primer coatings; examples include aromatic hydrocarbons such as toluene, xylene, and aromatic naphtha (Solvesso #100 (proprietary name) or the like); alcohols such as methanol, isopropyl alcohol, and n-butyl alcohol; ketones such as acetone, methyl ethyl ketone, and methyl amyl ketone; esters such as ethyl acetate, n-butyl acetate, 2-butoxyethyl acetate, amyl acetate, ethoxyethyl propionate; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons and the like. These organic solvents can be used alone or in combination of two or more.

[0073] The conductive primer coating composition of the present application can be produced by manufacturing (C) a conductive pigment paste by dispersing (A) the conductive pigment in (B) the non-chlorinated polyolefin resin containing a hydroxyl group, and then mixing the resulting (C) conductive pigment paste with (D) the acrylic resin-modified chlorinated polyolefin resin, (E) the blocked polyisocyanate compound, and optionally a resin, an additive, an organic solvent, or the like.

[0074] The (C) conductive pigment paste of the present application can be produced by mixing and dispersing (A) the conductive pigment, (B) the non-chlorinated polyolefin resin containing a hydroxyl group, and optionally an organic solvent, a resin, a non-conductive pigment, or the like as mentioned above. The non-volatile content in the (C) conductive pigment paste is 10 mass% to 50 mass% and preferably 15 mass% to 45 mass%.

[0075] It should be noted that the mixing and dispersing can be performed by a conventional method using known mixing and dispersing devices.

[0076] The method for coating the conductive primer coating composition of the present application is not particularly limited, but for example, it can be coated by air spraying, airless spraying, or high volume low pressure (HVLP) coating, etc. The conductive primer coating composition of the present application can impart excellent electrical conductivity to the plastic base material even when the conductive primer coating composition has not yet completely dried and still contains solvent. Although the dry film thickness of the primer coating film is not particularly limited, the dry thickness is preferably 2-20 µm. At a dry film thickness of 5-15 µm, even more excellent electrical conductivity can be imparted to the plastic base material, and this is particularly preferred. Furthermore, the primer coating film of the present application on the plastic base material preferably has a lightness L value in the CIE LAB color system of 20-70. By having a lightness L value in the CIE LAB color system on the plastic base material of 20-70, it is possible to prevent the color of the plastic base material from having an adverse effect on the color of the final coating film after coating of one or more topcoat materials.

[0077] The application of the coated plastic base material is not particularly limited; however, for example, automobile outer panel members such as bumpers, spoilers, grilles, fenders, etc., and automobile parts such as rearview mirrors, door handles, etc., are preferred.

[0078] As the material constituting the plastic base, for example, a polyolefin resin obtained by polymerizing one or two or more selected from among C 2-10 An olefin such as ethylene, propylene, butylene, methylbutene, hexene, butadiene, isoprene, etc., is preferred. A polyolefin resin alloy material of one or more polyolefins mixed with other resins can also be used. The other resins in these alloys include polyamide resins, poly(ethylene terephthalate) resins, poly(butylene terephthalate) resins, poly(vinyl chloride) resins, ethylene-propylene-diene monomer copolymer rubbers (EPDM), ethylene-propylene copolymer rubbers (EPR), thermoplastic elastomers, etc. The other resins used in these alloys can be used alone or in combination of two or more.

[0079] Other materials constituting the plastic base to be coated include, for example, polycarbonate resins, acrylonitrile-butadiene-styrene (ABS) resins, polycarbonate-acrylonitrile-butadiene-styrene (PCABS) resins, acrylate-styrene-acrylonitrile (ASA) resins, carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), polyurethane resins, nylons, etc.

[0080] These plastic substrate materials may contain one or two of the following: UV absorbers, antioxidants, mold release agents, antistatic agents, colorants, flame retardants, plasticizers, reinforcing materials such as glass fiber, and inorganic fillers, to meet the characteristics required for their application. Furthermore, these plastic substrate materials may undergo suitable pre-treatment using methods known to them, such as degreasing and washing.

[0081] The topcoat material coated on the conductive primer film obtained by coating the conductive primer coating composition of the present invention can be a single-coat coating composition, or a combination of a base coat coating composition and a clear coat coating composition.

[0082] As a single-coat coating composition, acrylic-polyurethane resin coating materials or polyester-polyurethane resin coating materials are typically used, provided that they can be cured at a temperature that will not cause deformation of the plastic substrate material. Alternatively, another thermosetting resin coating composition, such as acrylic-melamine resin coating materials, can be used. The single-coat coating composition can be one-component or two-component, and can be a solvent-based or water-based coating material, and various additives can optionally be incorporated.

[0083] In addition, pigments used in single-coat coating compositions include colored pigments, such as inorganic pigments like titanium dioxide pigments, iron oxide pigments, and composite oxide pigments like titanium yellow; organic pigments like azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, violet ketone pigments, benzimidazolone pigments, isoindoline pigments, isoindolineone pigments, azo metal chelate pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, thiophene pigments, indigo pigments, and carbon black; photoluminescent pigments like aluminum flake pigments, vapor-deposited aluminum pigments, alumina pigments, metal oxide-coated alumina pigments, mica pigments, metal oxide-coated mica pigments, and glass flake pigments; and extender pigments like calcium carbonate, barium sulfate, aluminum hydroxide, talc, and silica. These pigments can be used alone or in combination of two or more.

[0084] As base coat and clear coat compositions, similar to single-coat compositions, acrylic-polyurethane resin coatings or polyester-polyurethane resin coatings are typically used, provided they can cure at temperatures that do not cause deformation of the plastic substrate. Alternatively, another thermosetting resin coating composition, such as an acrylic-melamine resin coating, can be used. The base coat and clear coat compositions can be one-component or two-component, and they can be solvent-based or water-based coatings, with various additives optionally incorporated.

[0085] Further, pigments used in the basecoat paint composition include those mentioned above in the monocoat paint composition. These pigments can be used alone or in combination of two or more. Further, various pigments can also be contained in the clearcoat paint composition to the extent that transparency is not adversely affected.

[0086] The basecoat paint composition and the clearcoat paint composition can be wet-on-wet coated and then cured by heating at the same time, or the basecoat paint composition can be coated and cured by heating, and then the clearcoat paint composition can be coated and cured by heating.

[0087] There is no limitation on the method for coating these topcoat materials, for example, they can be coated by air spraying, airless spraying, or electrostatic coating, etc.; however, when coated onto the conductive coating film obtained by coating the conductive primer paint composition of the present application, electrostatic coating is preferably used. Although there is no particular limitation on the thickness of the topcoat coating film, the dry film thickness is preferably 20-60 µm in the case of the monocoat paint composition, 10-30 µm in the case of the basecoat paint composition, and 15-50 µm in the case of the clearcoat paint composition.

[0088] These topcoat coating films can be cured at room temperature (25°C), but in order to obtain sufficient coating film properties, they are preferably cured at a temperature of 50°C-120°C; 55°C-110°C is preferred, and 60°C-100°C is preferred. If the curing temperature is 50°C-120°C, sufficient coating film properties can be obtained without causing deformation of the coated material or yellowing of the coating film. The curing time varies with the curing temperature, but 5-60 minutes is suitable at a curing temperature of 50°C-120°C. Examples

[0089] The present application is described more specifically below by means of practical examples; however, the present application is not limited to these examples. Further, in the examples, "parts" means "mass parts" unless otherwise specified; and as to the content, "%" means "mass %".

[0090] Production Example 1

[0091] The (C) conductive paste was obtained by dispersing 10.0 parts by mass of Polytail H (a proprietary name, produced by Mitsubishi Chemical Corporation) as the (B) non-chlorinated polyolefin resin containing a hydroxyl group, 5.0 parts by mass of Chezacarb AC50 (a proprietary name, produced by Oren Oil Company) as the (A) black conductive pigment, and 5.0 parts by mass of titanium oxide pigment TI-PURE R-960 (a proprietary name, produced by Chemours Company) as the non-conductive pigment, as a resin solid, and diluting with xylene to give a non-volatile content of 20 mass% (resin solid + pigment). Then, these were dispersed to give a particle size of 20 µm or less by using a LAU-disperser Model DAS-200 (a proprietary name, produced by LAU) to obtain the (C) conductive paste.

[0092] Superchlon 223M (a proprietary name, produced by Japan Pulp and Paper Co., Ltd.) as the (D) chlorinated polyolefin resin modified with an acrylic resin, 5.0 parts by mass of Duranate MF-K60B (a proprietary name, produced by Asahi Kasei Corp.) as the (E) blocked polyisocyanate compound, 2.0 parts by mass of Superchlon 822 (a proprietary name, produced by Japan Pulp and Paper Co., Ltd.) as the non-hydroxyl-containing chlorinated polyolefin resin, and 3.0 parts of jER825 (a proprietary name, produced by Mitsubishi Chemical Corporation) as the epoxy resin were added to the total amount of the resulting (C) conductive paste, and mixed sufficiently to give the conductive primer coating composition P-1.

[0093] Production Examples 2-12 Comparative Production Examples 1-4

[0094] The conductive primer coating compositions P-2 to P-12 and the comparative primer coating compositions VP-1 to VP-4 were obtained by the same method as in Production Example 1, wherein the material formulations are presented in Table 1.

[0095] Comparative Example 5

[0096] Superchlon 223M (proprietary name, produced by Japan Pulp and Paper Co., Ltd.) as the (D) acrylic resin-modified chlorinated polyolefin resin, 5.0 parts by mass of Chezacarb AC50 (proprietary name, produced by Oren Oil Co.) as the (A) black conductive pigment, and 5.0 parts by mass of titanium oxide pigment TI-PURE R-960 (proprietary name, produced by DuPont-Toray Co., Ltd.) as the non-conductive pigment, without using the (B) non-chlorinated polyolefin resin containing a hydroxyl group, and diluted with xylene to give a non-volatile content of 20 mass% (resin solid + pigment). Then, these were dispersed to give a particle size of 20 µm or less using a LAU-disperser Model DAS-200 (proprietary name, produced by LAU) to obtain the (C) conductive paste.

[0097] Superchlon 223M (proprietary name, produced by Japan Pulp and Paper Co., Ltd.) as the (D) acrylic resin-modified chlorinated polyolefin resin, 10.0 parts by mass of Polytail H (proprietary name, produced by Mitsubishi Chemical Corporation) as the (B) non-chlorinated polyolefin resin containing a hydroxyl group, 5.0 parts by mass of Duramate MF-K60B (proprietary name, produced by Asahi Kasei Corporation) as the (E) blocked polyisocyanate compound, 2.0 parts by mass of Superchlon 822 (proprietary name, produced by Japan Pulp and Paper Co., Ltd.) as the chlorinated polyolefin resin not containing a hydroxyl group, and 3.0 parts by mass of jER825 (proprietary name, produced by Mitsubishi Chemical Corporation) as the epoxy resin were added to the total amount of the resulting (C) conductive paste, and sufficiently stirred to give a comparative primer coating composition VP-5. The comparative primer coating composition VP-5 contained the same material formulation as the conductive primer P-1, but the production method was different.

[0098] <Measurement of Surface Resistance>

[0099] The conductive primer compositions P-1 to P-12 of the present application and the comparative primer coating compositions VP-1 to VP-5 were coated onto a plastic base material, and the surface resistance 30 seconds after coating (30 seconds from completion of coating) was measured. The test pieces manufactured using (a) to (d) were used. Figure 1 Figure 1 Details of the test piece manufacture and details of the surface resistance measurement are as follows.

[0100] Example 1-1

[0101] Figure 1 ​(a) is a schematic view of a polypropylene plate 1 (length L 15 cm, width W 7 cm, thickness (not shown in the figure) 3 mm). The surface of the polypropylene plate 1 was wiped with isopropyl alcohol to remove dirt, and a commercial aluminum tape 3 (width 3.5 cm) was wound on both end portions la. Thereby, the longitudinal center lc (length (L’) 8 cm) of the polypropylene plate 1 between both end portions la covered with the aluminum tape 3 remained exposed.

[0102] Further, in order to connect the insulation resistance tester 7 (see below Figure 1 (d) to the polypropylene plate 1, a position lb 2.5 cm inward from both end portions la of the polypropylene plate 1 was determined as a terminal position lb to give a distance of 10 cm between terminals 7a of the insulation resistance tester 7, and as Figure 1 (b) pre-marked.

[0103] Then both end portions la of the polypropylene plate 1 were covered by the masking tape 5. Here, the masking tape 5 did not cover the entire aluminum tape 3. Thus, the masking tape 5 was pasted on the aluminum tape 3 so that the aluminum tape 3 on the center portion lc side of the polypropylene plate 1 remained exposed by a distance 1 (5 mm) in the longitudinal direction L of the polypropylene plate 1.

[0104] Then, the viscosity of the conductive primer coating composition P-1 was adjusted to 11 seconds at 20°C measured with a Ford cup #4 by dilution with xylene. The thus diluted conductive primer coating composition P-1 was applied by airless spraying onto the polypropylene plate in the masking state described above to give a dry film thickness of 7 µm. Figure 1 (c) shows the polypropylene plate 1 in the applied state.

[0105] Shortly after the application, the masking tape 5 was detached, and as Figure 1 (d) shown, the terminals 7a of the insulation resistance tester 7 (3-range insulation resistance meter, model 3301 (proprietary name, produced by Kyoritsu Electrical Instruments Works, Ltd.)) were fitted to the positions lb on the polypropylene plate 1 at both end portions on the aluminum tape 3.

[0106] The surface resistance 30 seconds after the application (30 seconds from the time of completion of the application) was measured, and the results are presented in Table 1. It should be noted that the unit of the measured values is “x 10 6 Ω”, and the acceptable range is 100 x 10 6 Ω or less.

[0107] Examples 1-2 to 1-12 and Comparative Examples 1-1 to 1-5

[0108] The surface resistance was measured 30 seconds after the application of the conductive primer coating compositions P-2 to P-12 of production examples 2 to 12 and the comparative primer coating compositions VP-1 to VP-5 of comparative examples 1 to 5 by the same method as example 1-1. The results are presented in table 1.

[0109] < Luminance L of the primer coating film < Measurement of the value

[0110] The luminance L of the primer coating film obtained from the conductive primer coating compositions P-1 to P-12 of the present application and the comparative primer coating compositions VP-1 to VP-5 was measured in the CIE LAB color system as described below

[0111] Example 2-1

[0112] The surface of a polypropylene plate (length 15 cm, width 7 cm, thickness 3 mm) was washed with isopropanol to remove adhering dirt. The viscosity of the conductive primer coating composition P-1 of production example 1 was adjusted to 11 seconds at 20 °C measured with a Ford cup #4 by dilution with xylene.

[0113] The so diluted conductive primer coating composition P-1 was applied by airless spraying onto the polypropylene plate treated as above to give a dry film thickness of 7 pm and cured for 10 minutes at 60 °C. This gave a cured coating film of the conductive primer coating composition P-1.

[0114] The luminance L of the resulting conductive coating film was measured using a spectrophotometer CM-512m3 (proprietary name produced by Konica Minolta, Inc.). The results are presented in table 1.

[0115] Examples 2-2 to 2-12 and comparative examples 2-1 to 2-5

[0116] The luminance L of the cured primer coating film of the conductive primer coating compositions P-2 to P-12 of production examples 2 to 12 and the comparative primer coating compositions VP-1 to VP-5 of comparative examples 1 to 5 was measured by the same method as example 2-1. The results are presented in table 1.

[0117] < Water resistance of the multi-layer coating film

[0118] The water resistance of the low temperature cured multi-layer coating film obtained by using the conductive primer coating compositions P-1 to P-12 of the present application and the comparative primer coating compositions VP-1 to VP-5 was measured as described below.

[0119] ​​1. Evaluation of polypropylene (PP) / primer / base coat (BC) / clear coat (CC) multilayer coated film

[0120] Example 3-1

[0121] The surface of a polypropylene plate (length 15 cm, width 7 cm, thickness 3 mm) as a substrate material was washed with isopropanol to remove adhered dirt. Then, the viscosity of the conductive primer coating composition P-1 produced in Example 1 was adjusted to 11 seconds at 20°C measured with a Ford cup #4 by dilution with xylene, and it was coated onto the polypropylene plate treated as above by airless spraying to give a dry film thickness of 7 pm and left at room temperature for 2 minutes.

[0122] Then, a solvent-based base coat Plymac No. 8800 Silver (proprietary name, produced by BASF Japan, Ltd., one-component acrylic coating composition) was electrostatically coated to give a dry coating film thickness of 15 pm, and then a solvent-based clear coat Plymac No. 8700 Clear (proprietary name, produced by BASF Japan, Ltd., two-component acrylic / polyurethane coating composition) was electrostatically coated by wet-on-wet to give a dry coating film thickness of 30 pm, and cured at 60°C for 10 minutes to give a test piece.

[0123] After immersing the resulting test piece in warm water at 40°C for 240 hours, a water resistance adhesion test was performed by an adhesion test (cross-hatch test) according to JIS K5400-8.5. Thus, in the adhesion test in the present invention, first, 11 longitudinal cuts and 11 transverse cuts were made at 2 mm intervals from the surface of the multilayer coated film to the substrate material with a cutting knife to make a cross-hatch grid having 100 squares. Then, Sellotape® was pasted on the entire surface of the cross-hatched multilayer film, and it was separated. The results of the water resistance adhesion test were evaluated by the following criteria here; the results are presented in Table 1.

[0124] O: The coated film did not peel off (100 / 100 of the remaining cross-hatch pattern)

[0125] A: The coated film partially peeled off (90-99 / 100 of the remaining cross-hatch pattern)

[0126] X: The coated film mostly peeled off (0-89 / 100 of the remaining cross-hatch pattern)

[0127] Examples 3-2 to 3-12 and Comparative Examples 3-1 to 3-5

[0128] Test pieces were manufactured using the conductive primer coating compositions P-2 to P-12 of production examples 2 to 12 and the comparative primer coating compositions VP-1 to VP-5 of comparative examples 1 to 5 and water resistance adhesion tests were performed by the same method as example 3-1. The results are presented in Table 1.

[0129] 2. Evaluation of polypropylene (PP) / primer / monocoat multilayer coating films.

[0130] Example 4-1

[0131] The surface of a polypropylene plate (length 15 cm, width 7 cm, thickness 3 mm) as a substrate material was washed with isopropanol to remove adhering dirt. Then, the viscosity of the conductive primer coating composition P-1 of production example 1 was adjusted to 11 seconds measured at 20 °C with a Ford cup #4 by dilution with xylene and it was applied by airless spraying onto the polypropylene plate treated as above to give a dry film thickness of 7 µm and kept at room temperature for 2 minutes.

[0132] Subsequently, a solvent-based monocoat metallic coating Hi-Urethane LM-110 Silver (proprietary name, produced by BASF Japan Ltd., two-component acrylic / polyurethane coating composition) was electrostatically applied to give a dry coating film thickness of 35 µm and cured at 60 °C for 10 minutes to give a test piece.

[0133] The resulting test piece was subjected to water resistance adhesion tests by the same method as example 3-1. The results are presented in Table 1.

[0134] Examples 4-2 to 4-12 and comparative examples 4-1 to 4-5

[0135] Test pieces were manufactured using the conductive primer coating compositions P-2 to P-12 of production examples 2 to 12 and the comparative primer coating compositions VP-1 to VP-5 of comparative examples 1 to 5 and water resistance adhesion tests were performed by the same method as example 4-1. The results are presented in Table 1.

[0136] 3. Evaluation of polycarbonate (PC) / primer / basecoat (BC) / clearcoat (CC) multilayer coating films

[0137] Example 5-1

[0138] The surface of a polycarbonate plate (length 15 cm, width 7 cm, thickness 3 mm) as a base material was washed with isopropyl alcohol to remove adhered dirt. Then, the viscosity of the conductive primer coating composition P-1 of Production Example 1 was adjusted to 11 seconds at 20°C measured with a Ford Cup #4 by dilution with xylene, and it was coated onto the polycarbonate plate treated as above by airless spraying to give a dry film thickness of 7 µm and left at room temperature for 2 minutes.

[0139] Then, the solvent-based basecoat paint Plymac No. 8800 Silver (proprietary name, produced by BASF Japan Ltd., one-component acrylic coating composition) was electrostatically coated to give a dry coating film thickness of 15 µm, and then the solvent-based clearcoat paint Plymac No. 8700 Clear (proprietary name, produced by BASF Japan Ltd., two-component acrylic / polyurethane coating composition) was electrostatically coated by wet-on-wet to give a dry coating film thickness of 30 µm, and cured at 60°C for 10 minutes to give a test piece.

[0140] The resulting test piece was subjected to the water resistance adhesion test by the same method as Example 3-1. The results are presented in Table 1.

[0141] Examples 5-2 to 5-12 and Comparative Examples 5-1 to 5-5

[0142] Test pieces were manufactured using the conductive primer coating compositions P-2 to P-12 of Production Examples 2 to 12 and the comparative primer coating compositions VP-1 to VP-5 of Comparative Examples 1 to 5, and subjected to the water resistance adhesion test by the same method as Example 5-1. The results are presented in Table 1.

[0143] [Table 1]

[0144]

[0145]

[0146] The materials in the table are as follows.

[0147] Chezacarb AC50: proprietary name, produced by Oren Oil Co., black conductive pigment

[0148] Dentall WK-500: proprietary name, produced by Otsukem Chemical Co., white conductive pigment

[0149] TI-PURE R-960: proprietary name, produced by Crompton Corp., titanium oxide pigment

[0150] Polytail H: a trade name, manufactured by Mitsubishi Chemical Corporation, non-chlorinated polyolefin resin containing a hydroxyl group, weight average molecular weight 13,000, hydroxyl value 46 mgKOH / g

[0151] NISSO-PB-G-3000: a trade name, manufactured by Nippon Soda Co., Ltd., non-chlorinated polyolefin resin containing a hydroxyl group, weight average molecular weight 7,800, hydroxyl value 27 mgKOH / g

[0152] NISSO-PB-G-1000: a trade name, manufactured by Nippon Soda Co., Ltd., non-chlorinated polyolefin resin containing a hydroxyl group, weight average molecular weight 4,900, hydroxyl value 73 mgKOH / g

[0153] Unistole P-801 : a trade name, manufactured by Mitsui Chemicals, Inc., non-chlorinated polyolefin resin containing a hydroxyl group, weight average molecular weight 86,000, hydroxyl value 40 mgKOH / g

[0154] Unistole P-902: a trade name, manufactured by Mitsui Chemicals, Inc., non-chlorinated polyolefin resin not containing a hydroxyl group, weight average molecular weight 80,000

[0155] Superchlon 223M: a trade name, manufactured by Japan Pulp and Paper Co., Ltd., chlorinated polyolefin modified with an acrylic resin, weight average molecular weight 57,000, hydroxyl value 20 mgKOH / g, chlorine content 5.0 mass%

[0156] Superchlon 224H: a trade name, manufactured by Japan Pulp and Paper Co., Ltd., chlorinated polyolefin modified with an acrylic resin, weight average molecular weight 70,000, hydroxyl value 56 mgKOH / g, chlorine content 13.0 mass%

[0157] Superchlon 240H: a trade name, manufactured by Japan Pulp and Paper Co., Ltd., chlorinated polyolefin modified with an acrylic resin, weight average molecular weight 84,000, hydroxyl value 7 mgKOH / g, chlorine content 4.5 mass%

[0158] Duranate MF-K60B: a trade name, manufactured by Asahi Kasei Corporation, malonic acid diester-terminated polyisocyanate compound

[0159] Superchlon 822: a trade name, manufactured by Japan Pulp and Paper Co., Ltd., chlorinated polyolefin resin not containing a hydroxyl group, weight average molecular weight 65,000, chlorine content 24.5 mass%

[0160] jER825: A proprietary name, manufactured by Mitsubishi Chemical Corporation, an epoxy resin with an epoxy equivalent of 175, which is liquid at room temperature (25°C).

[0161] The invention designed by the inventors of this invention has been described above in specific terms based on practical embodiments; however, it goes without saying that the invention is not limited to the above practical embodiments, and various variations are possible within its essence.

[0162] Keywords

[0163] 1...Polypropylene sheet (substrate material)

[0164] 3... Aluminum tape

[0165] 5...masking tape

[0166] 7...Insulation Resistance Tester

[0167] P-1... Conductive primer coating composition.

Claims

1. An electrically conductive primer coating composition characterized in that, The conductive primer coating composition comprises (C) a conductive pigment paste manufactured by dispersing (A) a conductive pigment in (B) a non-chlorinated polyolefin resin containing a hydroxyl group, (D) an acrylic resin-modified chlorinated polyolefin resin, and (E) a capped polyisocyanate compound.

2. The electrically conductive primer coating composition according to claim 1, wherein, The mass ratio of resin solids of the above (B) non-chlorinated polyolefin resin containing a hydroxyl group and (D) acrylic resin-modified chlorinated polyolefin resin is 10 / 90 to 60 / 40.

3. The electrically conductive primer coating composition according to claim 1 or 2, wherein, The total of resin solids of the above (B) non-chlorinated polyolefin resin containing a hydroxyl group and (D) acrylic resin-modified chlorinated polyolefin resin is 10 parts by mass or more in 100 parts by mass of total resin solids in the conductive primer coating composition.

4. The electrically conductive primer coating composition according to claim 1 or 2, wherein, The hydroxyl value of the above (B) non-chlorinated polyolefin resin containing a hydroxyl group is 15 to 90 mgKOH / g.

5. The electrically conductive primer coating composition according to claim 1 or 2, wherein, The mass average molecular weight of the above (D) acrylic resin-modified chlorinated polyolefin resin is 20,000 to 150,000.

6. The electrically conductive primer coating composition according to claim 1 or 2, wherein, The above (E) capped polyisocyanate compound is an active-methylene-capped polyisocyanate compound.

7. The electrically conductive primer coating composition according to claim 1 or 2, wherein, The above (A) conductive pigment includes a black conductive pigment and / or a white conductive pigment.

8. A method for producing a conductive primer coating composition, characterized by, manufacturing (C) a conductive pigment paste by dispersing (A) a conductive pigment in (B) a non-chlorinated polyolefin resin containing a hydroxyl group, and then mixing the above (C) conductive pigment paste, (D) an acrylic resin-modified chlorinated polyolefin resin, and (E) a capped polyisocyanate compound.

9. A primer coating film which is a dried coating film of the conductive primer coating composition described in claim 1.

10. The primer coating film according to claim 9, characterized by Brightness L in the CIE LAB color system on a plastic substrate The value is 20-70.

11. The primer coating film according to claim 9 or 10, characterized by The film thickness of the dried coating film is 2 to 20 µm.

12. A method for forming a multilayer coating film, characterized by, a step (1) of applying the conductive primer coating composition described in claim 1 or 2 to a plastic base material and forming a conductive primer coating film, applying a single-coat coating composition to the conductive primer coating film obtained in the above step (1) and curing.

13. A method for forming a multilayer coating film, characterized by, a step (1) of applying the conductive primer coating composition described in claim 1 or 2 to a plastic base material and forming a conductive primer coating film, applying a basecoat coating composition to the conductive primer coating film obtained in the above step (1) to obtain a basecoat coating film in a step (2), applying a clearcoat coating composition to the basecoat coating film obtained in the step (2) and curing.

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