JPH0418541B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a painted laminate with excellent weldability, workability, and corrosion resistance, and more particularly to a painted laminate with excellent continuous spot weldability, high workability, and high corrosion resistance suitable for steel materials for automobile bodies. In order to improve the spot weldability of pre-coated steel sheets, it is necessary for the coating film to have electrical conductivity, and conventionally this purpose has generally been achieved by using conductive pigments. However, in high-speed, large-volume, labor-saving lines such as automobile body production lines, continuous spot welding becomes an important issue. Continuous spot welding is important because as the number of welding increases, the electrode becomes contaminated with steel plates, plating films, coating compositions, etc., and must be cleaned or replaced. Evaluated by the number of welds. Techniques for imparting conductivity to paint films using conductive pigments (for example, Japanese Patent Publication No. 52-44569, Japanese Patent Application Laid-open No. 58-138758)
Spot welding is possible with techniques such as JP-A No. 58-174582, etc.) or technology that further improves the conductivity of the coating film by devising pigments (e.g. JP-A No. 51-79138, JP-A No. 58-19706). However, the requirements for ensuring continuous spot welding of 2000 points or more, that is, consideration for electrode contamination, are not taken into consideration, resulting in unsatisfactory results. Moreover, in modern automobile production processes, continuous spot welding is required to be as large as possible, for example, at 2,000 to 5,000 points. In addition, when pressing or deep drawing painted materials, the paint film may peel off into powder during processing and adhere to the press machine, causing processing scratches, increasing the frequency of cleaning the press machine, or The coating must not peel off from the base or crack, which may reduce the corrosion resistance of the area.
It is known to add an inorganic or organic lubricant for the purpose of improving the workability of this coating film. However, originally, weldable coatings tend to have a pigment-rich composition to ensure conductivity, and for example, inorganic pigments such as molybdenum disulfide, carbon, and lead oxide are used to fully demonstrate their effects. There is a problem in that adding too much of the compound leads to a decrease in the strength and processability of the coating film. In addition, in the production of automobiles, body parts such as car panels, doors, fenders, etc. are usually made from steel plates by press processing, assembled by spot welding, and then degreased, treated with phosphate, and then electrodeposited. In addition to processability and spot weldability, it is required to have good adhesion to electrodeposited coatings and corrosion resistance. Corrosion resistance is a problem, especially in areas where electrodeposition coating is insufficient, such as the joints and edges of parts. In general, when paints containing relatively large amounts of conductive pigments or lubricants are applied, the corrosion resistance of the paint film tends to decrease. The type and conditions of use are particularly important in obtaining a highly corrosion-resistant coating. Accordingly, one of the objects of the present invention is to provide a coated laminate having excellent workability, corrosion resistance, and continuous spot weldability. Another object of the present invention is to have excellent workability, corrosion resistance, and continuous spot weldability, as well as excellent coating film adhesion during post-coating such as electrodeposition coating, and corrosion resistance in areas where coating is insufficient, especially in automobiles. The purpose is to provide a prepainted steel sheet suitable for the production of products such as steel sheets. As a result of research into the relationship between continuous spot weldability and coating film composition, the present inventors have found that the thermal decomposition of the coating film binder resin is greatly involved in this continuous spot weldability, and that the thermal decomposition is in the resin molecule. The aromatic ring content varies depending on the coexistence of thermally decomposable substances and the aromatic ring content is 0 or within a certain limit, and continuous spots can be obtained by blending an appropriate amount of thermally decomposable substances. It has been found that weldability is significantly improved. In addition, in order to improve processability, since a considerable amount of inorganic pigment coexists, it is preferable to use a lubricant with a small amount, low specific gravity, and large volume, that is, an organic lubricant, which is suitable for high-level processing such as automobile bodies. I learned that the selection of the appropriate type and amount of lubricant, as well as the total amount of conductive pigments and other inorganic pigments, is by weight. Although a conductive pigment is naturally included in order to make it weldable, the present inventors were able to greatly improve the corrosion resistance of the laminate by providing a specific corrosion-resistant layer under the paint layer containing the conductive pigment. In addition, among conductive pigments, those containing iron phosphide as the main component have particularly excellent corrosion resistance and processability, and have stable low electrical resistance, do not melt during welding, and have high hardness. Furthermore, we discovered that by using an iron phosphide decomposition inhibitor to suppress the concentration of inorganic pigments, it was possible to obtain a laminate with higher corrosion resistance and excellent processability, weldability, and coating adhesion. The invention was completed. That is, according to the present invention, at least one chromium compound containing hexavalent chromium with a solubility of 20 to 15 ^-5 and an aqueous silica and/or an aqueous resin binder are essential on a metal substrate that has been subjected to a corrosion-resistant chemical pretreatment. A corrosion-resistant layer and a conductive paint layer of a composition containing a water-soluble chromium compound with a solubility of more than 20 are sequentially laminated, and the paint layer has an aromatic ring content in the molecule of 0 to 0 as solid content of the paint. 50% by weight Paint resin 10-35% by weight Organic lubricant 4-30% by weight Conductive pigments based on iron phosphide 15-85% by weight Iron phosphide decomposition inhibitors 1-71% by weight Other inorganic pigments 0- A corrosion-resistant painted laminate is provided which is a layer comprising a composition of 70% by weight, provided that the total amount of conductive pigment, iron phosphide decomposition inhibitor and other inorganic pigments is 35 to 86% by weight. The metal base materials in the laminate of the present invention include iron, zinc,
Aluminum metal materials, particularly cold-rolled steel sheets, galvanized steel sheets, alloy galvanized steel sheets, aluminium-plated steel sheets, zinc and zinc alloy sheets, aluminum and aluminum alloy sheets, stainless steel sheets, electrolytic galvanized steel sheets containing nickel or iron, and the like. After cleaning and degreasing, these metal substrates are usually subjected to a corrosion-resistant chemical pretreatment. Such chemical conversion pretreatment is a general chemical conversion treatment for forming phosphate coatings, chromate coatings, etc., and is well known to those skilled in the art, and there is no need to explain its details. In the present invention, the solubility is
A corrosion-resistant layer of a composition containing at least one chromium compound containing 20 to 10 ^-5 hexavalent chromium, an aqueous silica and/or an aqueous resin binder, and a water-soluble chromium compound having a solubility of greater than 20 is provided.
This corrosion-resistant layer contains a hexavalent chromium-containing chromium compound with a solubility of 20 to 10 ^-5 and a water-soluble chromium compound with a solubility of more than 20. Typical examples of the former are calcium chromate with a solubility of 20 to 10, and calcium chromate with a solubility of 10 to 10 ^-1
These include zinc chromate, strontium chromate, barium chromate and lead chromate with solubility of 10 ^-1 to ^{10 -5} . Further, it may be a mixture of a hexavalent chromium compound and another metal, or a compound that is a reaction product with an organic substance and has a solubility of 20 to 10 ^-5 . solubility is 20
A chromium compound with a solubility of less than 10 ^-5 has an insufficient anticorrosive ability, since the reaction with the coating resin is too active and the corrosion resistance of the coating film cannot be sufficiently improved. Such chromium compounds are usually one type or a combination of two or more types with a concentration of 0.01 in terms of metallic chromium.
It is present in the corrosion-resistant layer at a rate of about 1 g/m ² . In addition, water-soluble chromium compounds with solubility exceeding 20, such as CrO ₃ , Cr(NO ₃ ) ₃ , 9H ₂ O, Cr ₂ are used to obtain synergistic initial corrosion resistance and aging corrosion resistance.
(SO ₄ ) ₃ ·18H ₂ O, Cr(H ₂ PO ₄ ) ₃ , other chromates, dichromates, etc. are added. In the corrosion-resistant layer, water-based silica and/or water-based resin is used as a binder that is compatible with the chromium. Typical water-based silica is colloidal silica or water-dispersible silica with a particle size of 100 mμ or less. A specific example of such colloidal silica is Snowtex 0 (colloidal silica, trade name manufactured by Nissan Chemical Co., Ltd. Solid content 20% average particle Diameter 20mμ, PH
3.0), Snowtex N (PH9), Snowtex PL (average particle size 40 to 50 mμ, PH3), and as water-dispersible silica, Aerosil 300 (trade name, manufactured by Nippon Aerosil Co., Ltd., average particle diameter approximately 7m).
μ), Aerosil TT-600 (manufactured by Degussa, average particle size approx. 40 μm), Imusil A108 (average particle size approx. 5 μm,
(trade name manufactured by Illinois Minerals) etc. are preferably used. In addition, water-based resins include water-soluble resins and water-dispersible resins that are compatible with chromium, and specific examples of water-soluble resins include polyvinyl alcohol, alkylhydroxyalkyl cellulose, polyacrylic acid and its derivatives, polyacrylamide and its derivatives. derivatives, polyvinylpyrrolidone, reactants of polyvinylmethylmaleic anhydride and vinyl or acrylic compounds, etc. Specific examples of water-dispersible resins include alkyd resins, phenolic resins, amino resins, vinyl acetate emulsion polymers, styrene, etc. butadiene-based synthetic latex polymer,
Examples include acrylic emulsion polymers, natural and synthetic rubber emulsion polymers, and the like. These binders can be used alone or in combination of two or more, and are effective in tightly fixing the chromium compound to the metal surface. By providing the above-mentioned corrosion-resistant layer, a laminate that does not react with the resin component in the top coat, is stable against thermal deterioration, and exhibits excellent corrosion resistance over a long period of time can be provided. It has also been found that particularly excellent results are obtained when hexavalent chromium accounts for 10 to 90% by weight of the total water-soluble chromium in the corrosion-resistant layer. The laminate of the present invention has processability,
A specific conductive paint layer with excellent weldability and corrosion resistance is provided. This paint layer uses paint resins as binder resins, such as epoxy resins, alkyd resins, acrylic resins, melamine resins, and urethane resins, with an aromatic ring content in the molecule of 0 or up to 50% by weight. , phenolic resin, vinyl resin,
It is characterized by using polyvinyl butyral resin, polyvinyl acetate resin, chlorinated rubber, oil-free polyester resin, phthalic acid resin, styrene resin, polyolefin resin, etc. in organic solvent type or water-based type. These resins can be used alone or in combination of two or more, but in the case of a combination, the aromatic ring content expressed as an average content is 50% by weight or less, most preferably not 0%, as described above. must not. The present inventors have found that the aromatic ring content in the resin molecule is closely related to continuous spot weldability, and that when it exceeds 50%, the thermal decomposition rate is determined by the following measurement method: thermal decomposition rate = (1 - resin weight after heating). /Resin weight before heating) x 100 Resin weight after heating... Raise the temperature of the resin from room temperature to 550℃ at a rate of 20℃/min (in a _N2 gas flow), and calculate the weight when the sample temperature reaches 550℃. Measurement using a thermogravimetric analyzer (sample amount: 5 to 10 mg) is markedly reduced, and continuous spot weldability is also markedly reduced. Aromatic ring content is 0-50
In weight percent, the weight loss rate due to pyrolysis of the resin is 70
It has been found that at ~100%, it can sufficiently withstand continuous spot welding of up to 5,000 points. The content of resin in the solid content of the paint is 10 to 35% by weight, preferably 15 to 25% by weight. If it is less than 10% by weight, the processability will be significantly reduced, and if it exceeds 35% by weight, continuous spots will occur. It has also been found that weldability is reduced. The paint layer contains an organic lubricant as a second component. Organic lubricants are known as slip agents, which reduce the friction between the processing jig and the paint film, weaken the force applied to the paint film, and reduce damage to the paint film during processing. However, it is not only an organic substance with a low specific gravity and a large volume fraction in the coating film, but also has good thermal decomposition properties (decomposition temperature of 300 to 500
It exhibits an exothermic reaction at temperatures (°C), and most of it evaporates, leaving no carbon behind that would adversely affect continuous spot welding.
Furthermore, coexisting resins and thermal decomposition accelerators are preferable, and in this sense, polyolefin compounds such as polyethylene, isotactic polypropylene, polybutene, and polymers of unsaturated aliphatic olefin hydrocarbons (preferably molecular weight 1,000 to 10,000); Carboxylic acid ester compounds, such as stearic acid, oleic acid, adipic acid, adelaic acid, sebacic acid, etc., and n-butanol, sec.-butanol, 3
- Mono-, di- or poly-esters with alcohols such as methylbutanol, 2-ethylhexanoate, neopentyl alcohol; polyalkylene glycol compounds such as polypropylene glycol, polyethylene glycol, etc. are recommended as particularly preferred substances. processability,
Polyethylene wax is particularly preferred from the viewpoint of thermal decomposition properties, corrosion resistance, adhesion of the top coat, etc.
The most preferred one is a molecular weight of 1000-10000 and a particle size.
It is a polyethylene fine powder of 50μ or less. Such organic lubricants are used alone or in combination of two or more, and the amount added is 4 to 30% by weight, preferably 4 to 20% by weight, based on the solid content of the paint.
If it is less than 4% by weight, the processability will decrease and the effect of accelerating thermal decomposition of the resin will not be observed.
No further improvement in workability was observed, and on the contrary, there was a tendency for corrosion resistance to decrease as the amount increased. The coating composition used in the present invention also contains a conductive pigment for the purpose of imparting conductivity. Such conductive pigments can be of any conventional type, but include, for example, metal powders - stainless steel, gold, silver, cadmium, aluminum, zinc, tin, copper, graphite, etc. metal carbides - iron, nickel. , carbide ferroalloys such as titanium, tungsten, niobium, and manganese to ferromanganese, ferromolybdenum, ferrosilicon, ferrochrome, ferrotitanium, ferrophosphor, etc. One type or a mixture of two or more of these compounds is used. It is necessary to select a conductive pigment that has little adverse effect on corrosion resistance and processability, and it is preferable to exclude metal powders that exhibit a potential nobler than iron. In addition, it is preferable for a conductive pigment to have a stable and low electrical resistance, to not melt even when heat is generated during welding (no reduction in current density and no electrode contamination), and to have a hardness that does not shatter during welding pressure. . Also, since it is used in relatively large quantities, its low price is also a factor in its weight.
From these viewpoints, it is preferable to use iron carbide and iron phosphide. However, particularly desirable is iron phosphide, as described below. Therefore, in the present invention, conductive pigments containing iron phosphide as a main component (50% by weight or more) are particularly preferred. The conductive pigment has a particle size of 20 microns or less, preferably 10 microns or less, and is contained in an amount of 15 to 86% by weight, preferably 30 to 70% by weight of the solid content of the paint. When this pigment concentration is less than 30% by weight, the coating film thickness
If it is 10μ or more, the conductivity may be insufficient, and 15wt%
If it is below this value, the conductivity will be clearly insufficient and spot welding will not be possible. If it exceeds 70wt%, the processability of the coating may deteriorate, and if it exceeds 86wt%, the processability of the coating will clearly decrease and become impractical. In a particularly preferred embodiment, a pigment based on iron phosphide is used as the conductive pigment, and an iron phosphide decomposition inhibitor is used in combination to ensure better corrosion resistance. Iron phosphide is a preferable conductive pigment in terms of a good balance of various properties such as corrosion resistance, processability, and weldability, and as mentioned above, it is present in an amount of 15 to 86% by weight in the solid content of the paint. However, even if a conductive pigment with iron phosphide as its main component is selected, which has less negative effects on corrosion resistance, iron phosphide will still decompose under a corrosive environment, especially when the coating film is exposed to an acidic atmosphere, causing corrosion due to the decomposed products. It was found that this may be promoted. Whether or not the coating film becomes an acidic atmosphere depends on the coating composition, the base metal, and the corrosive environment conditions, but it is especially important for severe tests such as complex corrosion tests where several types of corrosive environments and alternating wet and dry conditions are set. , there is nothing better than this if a composition exhibiting a higher degree of corrosion resistance can be obtained. In order to obtain such a composition, the present inventors found that it was necessary to suppress the decomposition of iron phosphide or to render the decomposed products harmless, and for this purpose, the suspended water PH was 6 to 13,
It has been found that the coexistence of pigments, preferably from 7 to 11, is an extremely effective means as it keeps the coating film on the neutral or alkaline side. Therefore, the coating composition of the present invention contains an iron phosphide decomposition inhibitor as an essential component along with a conductive pigment mainly composed of iron phosphide. As mentioned above, such decomposition inhibitors are used for the purpose of keeping the coating film continuously neutral or alkaline, and the PH of the suspended water is 6.
~13 pigments are conveniently used. Specific examples include the following compounds. Alkaline earth metal petroleum sulfonates Chromate pigments such as lead chromate, potassium zinc chromate, zinc chromate, basic lead chromate, calcium chromate, strontium chromate, etc. Zinc phosphate, iron phosphate, aluminum tripolyphosphate, etc. Phosphate pigments Lead compound pigments such as calcium lead oxide and lead silicate Extender pigments such as talc, calcium carbonate, and silica Zinc dust (less than the same amount as iron phosphide) However, the amount of these pigments added is based on the solid content of the paint. 1st year of junior high school
The amount shall not exceed the total amount of inorganic pigments described below in weight percent or more. Although these compounds are sometimes classified as antirust pigments or extender pigments, they are recognized as iron phosphide decomposition inhibitors in the present invention in terms of the pH of suspended water. Since the iron phosphide decomposition inhibitor is used at 1% by weight or more in the solid content of such paints, it is easy to understand that the content of the conductive pigment mainly composed of iron phosphide is within the range of 15 to 85% by weight when both are used together. It will be. The paint layer of the present invention may also contain other inorganic pigments, such as chromium pigments (zinc chromate, lead chromate, calcium chromate, strontium chromate pigments, etc.) for improving corrosion resistance.
Phosphate pigments (zinc phosphate, iron phosphate, aluminum tripolyphosphate pigments, etc.), lead compound pigments (calcium leadate, lead silicate, etc.); adjustment of resin amount;
Extender pigments (silica, calcium carbonate, talc, alumina, etc.) and coloring pigments (chromium oxide, iron oxide, lead oxide, etc.) can be added to adjust the pH of the paint film. When adding such inorganic pigments, the total amount of inorganic pigments listed below must not be exceeded. That is, in the coating composition used in the present invention, the total amount of the conductive pigment mainly composed of iron phosphide, the iron phosphide decomposition inhibitor, and other inorganic pigments added as desired is 35 to 86% by weight, preferably 35 to 86% by weight, based on the solid content of the coating material. The weight is within the range of 35-70% by weight. This is because when the total amount is less than 35% by weight, the processability of the coating film decreases, and even when it exceeds 70% by weight, a decrease in processability may be observed, and when it exceeds 86% by weight, there is a clear decline in the processability. This is because a decrease in workability is observed. Therefore, according to the most preferred embodiment, the paint layer comprises: Paint resin having an aromatic ring content in the molecule of 0 to 50% by weight as paint solids 10 to 35% by weight Organic lubricant 4 to 30% by weight Phosphide Iron-based conductive pigment: 15-85% by weight Iron phosphide decomposition inhibitor: 1-71% by weight Other inorganic pigments: 0-70% by weight However, the total amount of conductive pigment, iron phosphide decomposition inhibitor, and other inorganic pigments 35-86% by weight of the composition. In addition, the thickness of the paint layer is 1 to 20μ in all cases.
Preferably, the baking treatment is performed at a thickness of 2 to 10 microns. The laminate of the present invention exhibits extremely excellent workability, corrosion resistance, continuous spot weldability, and coating adhesion, and is particularly useful for use in industrial production lines for automobiles and the like. The present invention will be explained below with reference to Examples. In the following examples, the following metal substrates were used. Metal base material that has not been subjected to corrosion-resistant chemical pretreatment: An electrolytic zinc-nickel alloy plated steel plate (plating weight: 40 g/m ² ) cleaned with a commercially available alkaline degreaser, washed with water, and dried. Metal base material subjected to corrosion-resistant chemical pretreatment: Chromic anhydride
% aqueous solution for 30 seconds at 50℃, then washed with water and dried. Example 1 The following chromate treatment solution was applied by roll coating to an electrolytic zinc-nickel alloy plated steel sheet that had not been subjected to chemical pretreatment, and then dried in a gas furnace for 1 minute to reach a maximum plate temperature of 150°C. 60mg/ ^m2
A chromate coating of the chromium layer was made. In addition, the solubility of the chromate treatment liquid is 6 to 8.
Zinc chromate (metallic chromium equivalent: 15g), polyacrylic acid (Dyurimer AC-10L, manufactured by Nippon Pure Chemical Industries, Ltd.)
(10 g in terms of solid content) and water were mixed so that the total amount was 1, and a liquid obtained by dispersing glass beads in a paint shaker for 1 hour was used. The following coating composition was separately prepared. Urethane-modified epoxy resin (JP-A-57-30717,
Adjusted according to Example 3, benzene ring content in molecule
45wt%), 16 parts by weight (solid content equivalent), resol type phenolic resin (manufactured by Showa Union Gosei Co., Ltd., BKS)
-316, benzene ring content in the molecule: 55 wt%) was melted in cyclohexanone, and 60 parts by weight of Ferrophos HRS2132 (iron phosphide-based conductive pigment manufactured by Hooker Chemicals and Plastics) was dissolved in cyclohexanone. Add 5 parts by weight of strontium chromate N (Kikuchi Color Products, chromate pigment as an iron phosphide decomposition inhibitor) and disperse with steel beads for 2 hours using a paint shaker. Filter the paint, add 15 parts by weight of Ceridust 3620 (manufactured by Hoechst, micronized polyethylene wax), mix uniformly with a disper, and adjust with cyclohexanone so that the non-volatile content is approximately 60 wt%. The coating composition was applied to the chromate-treated steel plate by a roll coating method, and baked in a gas furnace at a maximum plate temperature of 200°C for 1 minute to form a film with a coating thickness of 7 μm to obtain a corrosion-resistant painted laminate. Ta. Examples 2 to 7 and Comparative Examples 1 to 4 Painted laminates were obtained in the same manner as in Example 1, except that the metal base material, corrosion-resistant layer composition, and paint composition were changed as shown in Table 1 below. In addition, the solubility used in Example 2 etc. is 20
A chromate treatment solution containing a larger water-soluble chromium compound was prepared, for example, as follows. Chromic anhydride (metallic chromium equivalent: 20g) in 500ml of water
ml, add formalin to reduce a predetermined percentage of the total chromium, for example 40%, to Cr ³⁺ to make a partially reduced chromic acid aqueous solution, and then add, for example, 15 g of Aerosil 300 (manufactured by Nippon Aerosil Co., Ltd., humid silica), solubility 6 to 8 zinc chromate (metallic chromium equivalent: 15
Add g), make the total volume up to 1 with water, and disperse the glass beads in a paint shaker for 1 hour.

【table】

【table】

[Table] The following performance tests were conducted on the laminates obtained in each example and comparative example (3 days after preparation).
The results shown in Table 2 were obtained. Test method and evaluation criteria 1 Continuous spot welding Spot welding was carried out under the conditions of electrode diameter 5 mm, pressurizing force 200 kg, energization time 10 cycles, and current 8000 A, and the number of continuous dots that could be made was determined. Evaluation ◎: 5000 points or more Low electrode stain ○: 5000 points or more High electrode stain △: 3000 points to 5000 points
B1-142 type) with a wrinkle pressing pressure of 3 tons,
Punch diameter 50mmφ, die diameter 52.4mmφ, drawing depth
40mm, blank 95mm) to remove scratches on the paint film,
Checked for peeling. Evaluation ◎: No abnormality on the painted surface ○: There are scratches on the painted surface (not reaching the base metal) (10% or less) △: There are scratches that reach the base metal, and there are many scratches on the painted surface ×: Original plate crack 3 Corrosion resistance Combined corrosion test (1) Cycle = salt spray (5%
After 200 cycles of NaCl (35°C), 2 hours → drying (60°C), 2 hours → moistening (98%RH≦, 50°C), and 4 hours, the state of red rust and white rust on the flat surface was examined. Evaluation: ◎: No white rust, no red rust ○: Less than 5% white rust, no red rust △: 6% or more, ×: 1% or more red rust Salt water spray test (according to JIS-Z2371) 2000 After some time, the state of red rust and white rust on the flat surface was examined. Evaluation ◎: No white rust or red rust ○: Less than 5% white rust, no red rust △: 6% or more ×: 1% or more red rust

【table】

Claims (1)

[Scope of Claims] 1. On a metal base material subjected to corrosion-resistant chemical conversion pretreatment, (a) at least one chromium compound containing hexavalent chromium having a solubility of 20 to 10 ^-5 ; (b) aqueous silica and (c) a corrosion-resistant layer of a composition containing a water-soluble chromium compound having a solubility of greater than 20; and (a) a paint resin having an aromatic ring content in the molecule of 0 to 50% by weight. 10-35% by weight, (b) Organic lubricant 4-30% by weight (c) Conductive pigment whose main component is iron phosphide
15-85% by weight (d) Iron phosphide decomposition inhibitor 1-71% by weight (e) Other inorganic pigments 0-70% by weight Consists of conductive pigment (c), iron phosphide decomposition inhibitor (d) and others A corrosion-resistant paint laminate comprising conductive paint layers containing an inorganic pigment (e) in a total amount of 35 to 86% by weight. 2. The laminate according to claim 1, wherein the metal base material is an electrogalvanized steel sheet containing iron, zinc, aluminum metal, or nickel or iron. 3 Corrosion-resistant layer contains chromium compound in terms of metallic chromium
The laminate according to claim 1, containing 0.01 to 1 g/m ² . 4 In the corrosion-resistant layer, hexavalent chromium accounts for 10% of the total water-soluble chromium.
The laminate according to claim 1, which accounts for ~90% by weight. 5. The laminate according to claim 1, wherein the paint layer has a thickness of 1 to 20 μm. 6 Paint resins include epoxy resins, alkyd resins,
Claim 1: Acrylic resin, melamine resin, urethane resin, phenolic resin, vinyl resin, polyvinyl butyral resin, polyvinyl acetate resin, chlorinated rubber, oil-free polyester resin, phthalic acid resin, styrene resin, polyolefin resin The described laminate. 7. The laminate according to claim 1, wherein the organic lubricant is a compound selected from polyolefin compounds, carboxylic acid ester compounds, and polyalkylene glycol compounds. 8. The laminate according to claim 7, wherein the organic lubricant is a compound that exhibits exothermic decomposition at 300 to 500°C. 9. The laminate according to claim 1, wherein the iron phosphide decomposition inhibitor is a pigment exhibiting a suspension pH of 6 to 13. 10. The laminate according to claim 1, wherein the other inorganic pigment is a chromium pigment, a phosphate pigment, a lead pigment, or a colored pigment. 11. The laminate according to claim 1, wherein the total amount of the conductive pigment, iron phosphide decomposition inhibitor, and other inorganic pigments is 35 to 70% by weight based on the solid content of the paint.