Z720 - 1 - DESCRIPTION Title of Invention Precoated Metal Sheet Excellent in Conductivity and 5 Corrosion Resistance Technical Field [0001] The present invention relates to a precoated metal sheet which is covered by a film which contains an 10 organic resin and particles of a non-oxide ceramic with an electrical resistivity in a specific range at least at part of its surface and which is therefore excellent in conductivity and corrosion resistance. 15 Background Art [0002] Below, the background art of the present invention will be explained. [0003] The post-coated metal sheet which is coated after being shaped for use in home electrical appliances, 20 building materials, automobiles, etc. is being replaced by precoated metal sheet which is covered with a colored organic film. A precoated metal sheet, in most cases, has excellent corrosion resistance and workability and coating film adhesion due to the composite effects of the 25 metal itself (in the case of a plated metal sheet, the plating film) and the chemical conversion at the layer above it and, furthermore, the primer film at the layer above that and, furthermore, in many cases is provided with a colored organic film at its top surface, so the 30 coating operation after working can be eliminated and a high productivity and beautiful appearance can be obtained. [0004] When press-forming a precoated metal sheet, the film layer which is covered over the metal sheet is also 35 shaped, so the film is also required to have workability. For this reason, a film layer based on a resin is the general practice. The covering film of a precoated metal - 2 - sheet is usually insulating. However, in precoated metal sheets, a need for electroweldability at the time of assembly of parts and a need for groundability, electromagnetic shieldability, and other high 5 conductivity when used for home electrical appliances or the housings for OA equipment have arisen. In response to these demands for imparting conductivity to films, the art has been proposed of covering a metal sheet with a film which contains conductive particles to thereby 10 impart conductivity. [0005] Among these, as art which uses conductive metal particles, for example, PLT 1 proposes the art of covering an aluminum or aluminum alloy substrate surface with a resin film which contains aluminum or aluminum 15 alloy powder through a chromate film which strengthens the corrosion resistance of the substrate or the adhesion with the substrate so as to thereby obtain a precoated aluminum or aluminum alloy material for home electric appliance products or chassis parts which realizes both 20 excellent corrosion resistance and conductivity. The amount of the aluminum or aluminum alloy powder which is used for the resin film is described as being from 10 to 50 parts by weight with respect to 100 parts by weight of the resin. 25 [0006] PLT 2 proposes the art of a galvannealed steel sheet which has a resin-based conductive coating film which contains zinc powder. It is stated that inclusion of zinc powder in the coating film in 30 to 90 mass% is preferable and that a coating film thickness of 2 to 30 30 ~m is preferable. PLT 3 proposes the art of using a resin film which contains 2 to 50 mass% of a metal powder, 1 to 50 mass% of water, and 0.5 to 30 mass% of a surfactant as essential ingredients and has a thickness of 5 ~m or less 35 so as to cover a metal sheet to raise its conductivity. It is stated that as the metal powder, nickel powder is suitable and as the coating for coating use, a water- 3 - based one is preferable. [0007] Further, among the art for imparting conductivity to a film, as art which enables use of conductive particles other than metal particles, for 5 example, PLT 4 discloses the art of an organic composite plated steel sheet which has, on a rust-prevention layer mainly comprised of a chrome compound, an organic resin coating of 0.5 to 20 ~ thickness containing 3 to 59 vol% of a conductive powder. PLT 5 proposes the art of an 10 organic coated plated steel sheet which has a resin-based film which contains 3 to 59 vol% of a conductive material. As the conductive material, various metals and their alloys, iron phosphate or ferrosilicon or other iron compounds, etc. may be mentioned. PLT 6 discloses 15 the art of a conductive precoated metal sheet which has a 0.5 to 3 ~ thick coating film which contains any conductive metal oxide. As the conductive metal oxide, it is stated that one which includes zinc oxide of a particle size of 5.0 ~m or less and an average 2 ~m in 40 20 to 50 parts by mass with respect to 100 parts by mass of resin is desirable. PLT 7 proposes as a metal surface coating agent which enables the formation of a conductive, weldable corrosion resistant film after curing at the metal surface, a water-based coating agent 25 which contains a specific organic binder in 10 to 30 mass% and a conductive material powder in 30 to 60 mass%. As examples of conductive material powder which is suitable for preparation of the present coating agent, zinc, aluminum, graphite, carbon black, molybdenum 30 sulfide, and iron phosphate may be mentioned. PLT 8 proposes the art of automobile-use organic precoated steel sheet which achieves both excellent corrosion resistance and weldability by covering the surface of zinc-based plate steel sheet or aluminum-based plated 35 steel sheet with a first layer film which strengthens the adhesion with the plating and, through that, a resin- 4 - based second layer film which includes a rust-proofing additive and a conductive pigment. The conductive pigment is contained in the film in an amount of 5 to 70 vol%. The film thickness is 1 to 30 ~. As a suitable 5 conductive pigment, a metal, alloy, conductive carbon, iron phosphate, carbide, and semiconductor oxide may be illustrated. [0008] Further, as art which uses conductive ceramic particles among conductive particles other than metal 10 particles, for example, PLT 9 proposes the art of a conductive material-coated corrosion resistant metal material which is excellent in corrosion resistance and conductivity comprised of core metal which is covered by a clad layer comprised of a corrosion resistant metal 15 and, furthermore, is covered over that by a surface treatment layer comprised of at least one conductive material selected from a carbon material, conductive ceramic, and metal powder and of any resin which binds the same. 20 Citations List Patent Literature [0009] PLT 1 : Japanese Patent Publication No. 2000- 212764 Al 25 PLT 2: Japanese Patent Publication No. 55-17508 Al PLT 3 : Japanese Patent Publication No. 2004-17455 Al PLT 4 : Japanese Patent Publication No. 9-276788 Al PLT 5 : Japanese Patent Publication No. 11-138095 Al PLT 6 : Japanese Patent Publication No. 7-313930 Al 30 PLT 7 : Japanese Patent Publication No. 2003-513141 Al PLT 8 : Japanese Patent Publication No. 2005-288730 Al PLT 9 : Japanese Patent Publication No. 2003-268567 Al Summary of Invention 35 Technical Problem [0010] As explained ln the section on "Background Art", in precoated metal sheets, a need for - 5 - electroweldability at the time of assembly of parts and a need for groundability and other higher conductivity when used for household electrical appliances and parts office automation equipment have arisen. Such a trend also 5 applies to inexpensive precoated metal sheet designed for indoor household electrical appliances and interior building materials. In this regard, if using the art such as in PLT 1 or PLT 4 with the intent of solving these problems, to obtain the desired corrosion resistance and 10 conductivity, it is necessary to use a chromate film or chrome compound-containing rust-proofing layer as a primer layer. This does not match the current need for avoiding the effects of the toxic nature and environmental load of hexavalent chrome. 15 [0011] If using zinc powder as conductive particles like in PLT 2, using Fe-Si alloy, Fe-Co alloy, Fe-Mn alloy, or other ferrous alloys as conductive particles in PLT 4, or, further, using zinc or aluminum powder in PLT 7, if using plated steel sheet containing these In the 20 coating film in a usual moist environment indoors or outdoors, there were the difficulties that a rust layer or a thick oxide insulating layer would form on the surface of the zinc powder or alloy, the powder and resin would separate at their interface, and the conductivity 25 of the coating film would be lost. [0012] In PLT 3 as well, use of nickel powder is recommended. Nickel is excellent in relative water resistance, so even if using a metal sheet which contains this in a coating film in a usual moist environment 30 indoors or outdoors, the conductivity of the coating film is held to a certain extent. However, the dependency on overseas nickel resources is high. The changing situations and oligopoly etc. of the producing countries mean there is a risk of the resources not being able to 35 be stably and inexpensively acquired over the long term in the future. Further, nickel has a specific gravity of 8.85 and is relatively heavy as conductive particles, so - 6 - when using a roll coater or curtain coater etc. to coat the coating on a metal sheet in mass production, the nickel particles inside the coating rapidly settled and did not easily enter the coating film resulting in the 5 desired conductivity often not being able to be obtained. Furthermore, in PLT 3, use of a water-based coating is recommended, but when using a water-based coating which contains nickel particles, there was the difficulty that with storage for several weeks or so, the surface layers 10 of the particles would oxidize and blue-green color nickel oxide (II) (NiO) would form and float free in the water thereby contaminating the coating. [0013] Further, in PLT 7, a water-based coating-use coating is used, so when using zinc and aluminum as 15 conductive particles, in the same way as the case of PLT 3, there was the defect that the water coexisting in the water-based coating or film caused a rust layer to form on the metal powder surface and caused the conductivity to become inferior. 20 [0014] In this way, in the prior art, it is not easy to obtain a precoated metal sheet which achieves both sufficient conductivity and corrosion resistance without jointly using a chromate primer layer (PLTs 1 and 4). If using nickel particles as conductive particles, 25 industrial application is difficult due to the ease of settling of nickel due to its high specific gravity, unstable prices, etc. (PLT 3). It is not possible to obtain a precoated metal sheet which maintains the corrosion resistance of the precoated metal sheet and 30 enables use of a coloring pigment to color the sheet to a desired color tone by keeping down the amount of addition of conductive particles (PLTs 4 to 9), Further, if selecting particles of base metals for which surface oxide films easily form due to moisture, during the use 35 of the steel sheet, an oxide insulating layer or rust layer is formed and sufficient conductivity cannot be obtained (PLTs 2, 4, and 7). In this and other ways, - 7 - there have been various problems. [0015] As explained above, a precoated metal sheet is being asked to provide both conductivity, more specifically electroweldability at the time of assembly 5 of parts and groundability in the case of use for parts of household electrical appliances or office automation equipment, and corrosion resistance and aesthetic appearance. To provide such a precoated metal sheet, it has been necessary to provide the desired conductivity, 10 corrosion resistance, and coloring ability by a coloring pigment by addition of a small amount of conductive particles which are stable and maintain good dispersability in the coating-use coating or during use of the precoated metal sheet. 15 The present invention was made in consideration of the above such problems and relates to a chromate-free conductive, corrosion resistant precoated metal sheet which is covered at least at part of its surface with a film which contains a small amount of non-oxide ceramic 20 particles with an electrical resistivity limited to an extremely low range. Solution to Problem [0016] The inventors engaged in intensive research for 25 achieving the above-mentioned such object and as a result discovered that if forming on a metal surface a film which contains a small amount of non-oxide ceramic particles with an electrical resistivity of 0.lxl0-6 to 185xl0-6 ncm which are selected from borides, carbides, 30 nitrides, and silicides, which can be relatively inexpensively obtained industrially, in an organic resin, a conductive, corrosion resistant precoated metal sheet which is excellent in all of conductivity, corrosion resistance, and coloring ability by a coexisting coloring 35 pigment can be obtained. [0017] The present invention was completed based on the above findings and specifically is as follows: - 8 - [0018] (1) A conductive, corrosion resistant precoated metal sheet comprising a metal sheet on at least one surface of which is formed a coating film (a) which contains an organic resin (A) and non-oxide ceramic 5 particles (B) with a 25°C electrical resistivity of 0.lx10-6 to 185x10-6 Qcm selected from borides, carbides, nitrides, non-oxide and silicides, a volume ratio of the organic resin (A) and the non-oxide ceramic particles (B) in the coating film (a) at 25°C being 90:10 to 99.9:0.1, 10 the organic resin (A) including a resin (A1) which includes at least one type of functional group selected from a carboxyl group and sulfonic acid group in a structure of the resin (A1) or further a derivative (A2) of that resin (A1). 15 [0019] (2) The conductive, corrosion resistant precoated metal sheet as set forth in (1) characterized in that the non-oxide ceramic particles (B) have a 25°C electrical resistivity of 0.lx10-6 to 100x10-6 Qcm. [0020] (3) The conductive, corrosion resistant 20 precoated metal sheet as set forth in (1) or (2) characterized in that the coating film (a) has a thickness of 2 to 10 ~. [0021] (4) The conductive, corrosion resistant precoated metal sheet as set forth in (1) or (2) 25 characterized in that the resin (A1) or derivative (A2) of the resin (A1) further includes at least one type of functional group selected from an ester group, urethane group, and urea group in the structure of the resin (A1) or the derivative (A2). 30 [0022] (5) The conductive, corrosion resistant precoated metal sheet as set forth in (4) characterized in that the resin (A1) is a polyurethane resin (Alu) which includes a urea group in the structure of the polyurethane resin (Alu). 35 [0023] (6) The conductive, corrosion resistant precoated metal sheet as set forth in (5) characterized - 9 - in that the resin (AI) is a mixed resin of a polyurethane resin (Alu) which includes a urea group in the structure of the polyurethane resin (Alu) and a polyester resin (Ale) which includes an aromatic dicarboxylic acid as a 5 carboxylic acid component and includes a sulfonic acid group in the structure of the polyester resin (Ale). [0024] (7) The conductive, corrosion resistant precoated metal sheet as set forth in (1) or (2) characterized in that the derivative (A2) of the resin 10 (AI) is a resin (A2 si ) of the following general formula (I) : I General formula (I) ( I ) (wherein, the notation "AI" indicates the resin (AI), "Z" indicates a C1 to Cg, No to N2' 00 to 02 hydrocarbon 15 chain, and the notation "Al-Z" indicates a covalent bond of "AI" and "Z" through functional groups of the two. Further, "-0-" is an ether bond, "-OH" is a hydroxyl group, and "-X" is a C1 to C3 hydrolysable alkoxy group, hydrolysable halogen group, or hydrolysable acetoxy (10) The conductive, corrosion resistant 30 20 group, "-R" is a Cl to C3 alkyl group, "a", "b", "c", and "d" which show the numbers of substituents are all integers of 0 to 3, and a+b+c+d=3) [0025] (8) The conductive, corrosion resistant precoated metal sheet as set forth in (1) or (2) 25 characterized in that the organic resin (A) is a resin which is cured by a curing agent (C). [0026] (9) The conductive, corrosion resistant precoated metal sheet as set forth in (8) characterized in that the curing agent (C) contains a melamine resin (Cl) . [0027] - 10 - precoated metal sheet as set forth in (1) or (2) characterized in that the non-oxide ceramic particles (B) are a boride ceramic M02B, MoB, MoB2, NbB, NbB2, TaB, TaB2, TiB, TiB2' VB, VB2, W2Bs , or ZrB2; a carbide ceramic B4C, 5 MoC, M02C, Nb2C, NbC, SiC, Ta2C, TaC, TiC, V2C, VC, WC, W2C, or ZrC; a nitride ceramic M02N, Nb2N, NbN, Ta2N, TiN, or ZrN; a silicide ceramic Mo3Si, MoSi2, NbSi2, Ta2Si, TaSi2, TiSi, TiSi2, VsSi3 , VSi2, W3Si, WSi2, ZrSi, or ZrSi2; or a mixture of two or more types selected from these. 10 [0028] (11) The conductive, corrosion resistant precoated metal sheet as set forth in (1) or (2) characterized in that the coating film (a) is formed by coating a water-based precoating-use composition. 15 Advantageous Effects of Invention [0029] According to the present invention, by just adding a small amount of a conductive material to a coating film, it is possible to provide a precoated metal sheet which gives a coating film conductivity realizing 20 sufficient groundability and weldability. Further, the precoated metal sheet of the present invention also has excellent corrosion resistance. Further, by adding a coloring pigment in advance to the water-based or solvent-based or other precoating-use composition for 25 obtaining the coating film of the present invention, it is possible to easily provide a precoated metal sheet which can be easily colored to the desired color tone. Brief Description of Drawings 30 [0030] FIG. 1 is a schematic view of the cross-section of a conductive, corrosion resistant precoated metal sheet of the present invention. Description of Embodiments 35 [0031] Below, the present invention will be explained in detail. [0032] • 5 10 15 20 25 30 35 - 11 - The precoated metal sheet of the present invention is a metal sheet which is covered at least at part of its surface by a specific conductive coating film. According to the application, both surfaces of the metal sheet may be covered by the coating film or only a single surface may be covered. Further, part of the surface may be covered or the entire surface may be covered. The locations of the metal sheet which are covered by the coating film are superior in conductivity and corrosion resistance. [0033] As the metal forming the metal sheet which can be used for the precoated metal sheet of the present invention, for example, aluminum, titanium, zinc, copper, nickel, steel, etc. may be used. The ingredients of these metals are not particularly limited. For example, when using steel, it may be ordinary steel or may be steel containing chrome or other additive elements. However, if using the metal sheet of the present invention for strong ironing or deep drawing applications, in the case of each metal, it is preferable to suitably control the types or amounts of addition of the additive elements and the metal structure so as to be suitable for strong ironing or deep drawing. Further, when using steel sheet as the metal sheet, the surface may have a covering plating layer, but the type is not particularly limited. As the applicable plating layer, for example, platings comprised of any of zinc, aluminum, cobalt, tin, or nickel and alloy platings which contain these metal elements and further other metal elements or nonmetal elements etc. may be mentioned. In particular, as zinc-based plating layers, for example, platings comprised of zinc, alloy platings of zinc and at least one of aluminum, cobalt, tin, nickel, iron, chrome, titanium, magnesium, and manganese, or various galvannealed platings which contain further other metal elements or nonmetal elements (for example, four-way alloy platings of zinc with aluminum, magnesium, and silicon) may be mentioned, but the alloy • 5 10 15 20 25 30 35 - 12 - ingredients other than the zinc are not particularly limited. Further, these plating layers which contain small amounts of different metal elements or impurities such as cobalt, molybdenum, tungsten, nickel, titanium, chromium, aluminum, manganese, iron, magnesium, lead, bismuth, antimony, tin, copper, cadmium, arsenic, etc. and which have silica, alumina, titania, and other inorganic substances dispersed in them are included. [0034] As aluminum-based plating layers, aluminum or alloy platings of aluminum and at least one of silicon, zinc, and magnesium (for example, alloy platings of aluminum and silicon, alloy platings of aluminum and zinc, three-way alloy platings of aluminum, silicon, and magnesium), etc. may be mentioned. [0035] Furthermore, composite platings of combinations of the above platings and other types of platings, for example, iron plating, iron and phosphorus alloy plating, nickel plating, cobalt plating, etc. may also be used. [0036] The method of forming the plating layer is not particularly limited. For example, electroplating, electroless plating, hot dipping, deposition plating, dispersal plating, etc. may be used. The plating treatment method may be either the continuous or batch type. Further, when using steel sheet, as treatment after plating, treatment for making the appearance uniform after hot dipping, that is, zero spangle treatment, treatment for reforming the plating layer, that is, annealing treatment, temper rolling for adjusting the surface conditions and material quality, etc. are possible, but the present invention is not particularly limited to these. Any may be used. [0037] The non-oxide ceramic particles (B) which are contained in the coating film of the present invention must be a boride ceramic, carbide ceramic, nitride ceramic, or silicide ceramic with a 25°C electrical resistivity 10 (volume resistivity, specific electrical resistance) of o.lx10-6 to 185x10-6 Ocm in range. The "non-oxide ceramic" referred to here is a ceramic which is comprised of elements or compounds not containing oxygen. Further, the "boride ceramic", "carbide ceramic", "nitride ceramic", 15 and "silicide ceramic" referred to here are non-oxide ceramic which respectively have boron B, carbon C, nitrogen N, and silicon Si as main nonmetal component elements. Among these, none can be found with a 25°C electrical resistivity of less than 0.lx10-6 Ocm. Further, 20 if the 25°C electrical resistivity (volume resistivity, specific electrical resistance) exceeds 185x10-6 Ocm, a large amount must be added to impart sufficient conductivity to the resin coating film. During use of the precoated metal sheet of the present invention, a large 25 number of conduction paths for corrosive current which pass through coating film are formed and the corrosion resistance deteriorates, so this is not suitable. Further, with a large amount of addition, the coating film appearance is dominated by the color of the large 30 amount of conductive particles. Even if adding a coloring pigment, the desired color tone cannot be colored to. [0100] The non-oxide ceramic particles (B) which are contained in the coating film of the present invention are preferably a boride ceramic, carbide ceramic, nitride 35 ceramic, or silicide ceramic with a 25°C electrical resistivity of 0.lx10-6 to 100x10-6 Ocm in range. These • 5 10 15 20 25 30 35 - 43 - particles have a higher conductivity than particles with a 25°C electrical resistivity of over 100xl0-6 ncm to 185xl0-6 ncm in range, so the amount of addition for imparting sufficient conductivity to the resin coating film may be made smaller and as a result the detrimental effect on the corrosion resistance or coating film appearance of the precoated metal sheet becomes smaller. Note that, by way of reference, pure metal has an electrical resistivity of 1.6xl0-6 ncm (Ag alone) to 185xl0-6 ncm (Mn alone) in range. It is learned that the non-oxide ceramic which are used as conductive particles in the present invention (electrical resistivity 0.lxl0-6 to 185xl0-6 ncm) have excellent conductivities of the same extent as pure metals. [0101] As the non-oxide ceramic which can be used in the present invention, the following may be illustrated: That is, as boride ceramic, borides of transition metals or rare earth elements of Group IV (Ti, Zr, Hf), Group V (V, Nb, Ta), or Group VI (Cr, Mo, W) of the Periodic Table, as carbide ceramic, carbides of Group IV, Group V, and Group VI transition metals and rare earth elements or B or Si, as nitride ceramic, nitrides of Group IV, Group V, and Group VI transition metals or rare earth elements, as silicide ceramic, Group IV, Group V, and Group VI transition metals or rare earth elements, or mixtures of two or more types of compounds selected from these borides, carbides, nitrides, and silicides or these ceramic mixed with metal binding materials and sintered to obtain cermets etc. may be illustrated. [0102] When preparing the coating film (a) from the water-based coating, the metal forming part of the cermet preferably has a standard electrode potential of -0.3V or more and water resistance. If the metal forming part of the cermet has a standard electrode potential of less than -0.3V, if the precoated metal sheet which has this cermet powder in its coating film is used in a moist - 44 - environment for a long period of time, a rust layer or a thick oxide insulating layer may form on the surface of the powder, the interface between the powder and resin may separate, and the coating film may lose conductivity. 5 As examples of such water resistant cermet powder, WC12Co, WC-12Ni, TiC-20TiN-15WC-10Mo2C-5Ni, etc. may be mentioned. The standard electrode potentials of Co and Ni are respectively -0.28V, -0.25V or both more precious than -0.3V. Both metals have water resistance. 10 [0103] Among the non-oxide ceramic, Cr-based ceramic are not available on the market due to concerns over the environmental load. Further, most rare earth elementbased and Hf-based ceramic are high in price. Therefore, in the present invention, it is preferable to use a 15 boride, carbide, nitride, or silicide of elements other than these in the group such as Ti, Zr, V, Nb, Ta, Mo, or W or carbides of B or Si or mixtures of two or more types selected from these. [0104] Furthermore, from the viewpoint of the 20 existence of industrial products and the stable availability in the domestic and foreign markets, price, electrical resistivity, etc., the following non-oxide ceramic are more preferred. That is, Mo2B (electrical resistivity of 40x10-6 ncm) , MoB (same, 35x10-6 ncm) , MoB2 25 (same, 45x10-6 ncm) , NbB (same, 6.5x10-6 ncm) , NbB2 (same, 10x10-6 ncm) , TaB (same, 100x10-6 ncm) , TaB2 (same, 100x106 ncm) , TiB (same, 40x10-6 ncm) , TiB2 (same, 28x10-6 ncm) , VB (same, 35x10-6 ncm) , VB2 (same, 150x10-6 ncm) , W2Bs (same, 80x10-6 ncm) , ZrB2 (same, 60x10-6 ncm) , B4C (same, 30 0.3x10-6 ncm) , MoC (same, 97x10-6 ncm) , M02C (same, 100x106 ncm) , Nb2C (same, 144x10-6 ncm) , NbC (same, 74x10-6 ncm) , SiC (same, 107x10-6 ncm) , Ta2C (same, 49x10-6 ncm) , TaC (same, 30x10-6 ncm) , TiC (same, 180x10-6 ncm) , V2C (same, 140x10-6 ncm) , VC (same, 150x10-6 ncm) , wc (same, 80x10-6 35 ncm) , W2C (same, 80x10-6 ncm) , ZrC (same, 70x10-6 ncm) , • 5 10 15 20 25 30 35 - 45 - M02N (same, 20xl0-6 Ocm) , Nb2N (same, 142xl0-6 Ocm) , NbN (same, 54xl0-6 Ocm) , Ta2N (same, 135xl0-6 Ocm) , TiN (same, 22xl0-6 Ocm) , ZrN (same, 14xl0-6 Ocm) , M03Si (same, 22xl0-6 Ocm) , MoSi2 (same, 22xl0-6 Ocm) , NbSi2 (same, 6.3xl0-6 Ocm) , Ta2Si (same, 124xl0-6 Ocm) , TaSi2 (same, 8. 5xl0-6 Ocm) , TiSi (same, 63xl0-6 Ocm) , TiSi2 (same, 123xl0-6 Ocm) , VsSi3 (same, 115xl0-6 Ocm) , VSi2 (same, 9.5xl0-6 Ocm) , W3Si (same, 93xl0-6 Ocm) , WSi2 (same, 33xl0-6 Ocm) , ZrSi (same, 49xl0-6 Ocm) , ZrSi2 (same, 76xl0-6 Ocm) , or mixtures of two or more types selected from these are preferably used. [0105] Among these as well, non-oxide ceramic with an electrical resistivity at 25°C of 0.lxl0-6 to 100xl0-6 Ocm are particularly preferable. The reason is that these have higher conductivity than non-oxide ceramic with a 25°C electrical resistivity of over 100xl0-6 Ocm to 185xl06 Ocm in range, so the amount of addition of particles for imparting sufficient conductivity to the resin coating film may be made smaller, only a few conduction paths for corrosion current which pass through the coating film are formed, and the corrosion resistance does not drop much at all. Further, due to the addition of the very small amount of particles, the coating film appearance is not dominated by the color of the conductive particles and even if adding a coloring pigment, the desired colored tone can be easily colored to. [0106] The electrical resistivities which are given to the non-oxide ceramic are respectively representative values (documented values) of ceramic being sold and used as industrial materials. These electrical resistivities increase and decrease depending on the types or amounts of impurity elements which entering into the crystal lattices of the non-oxide ceramic, so when using the ceramics in the present invention, for example, it is • 5 10 15 20 25 30 35 - 46 - sufficient to use them after measuring the 25°C electrical resistivity based on JIS K7194 by the four-terminal, four-probe method using a Mitsubishi Chemical resistance meter Loresta EP (Model MCP-T360) and ASP probes and the constant current application method and confirming that it is 0.lxl0-6 to 185xl0-6 Ocm in range. [0107] The non-oxide ceramic particles (B) preferably have particle shapes of spherical particles or quasi spherical particles (for example, ellipsoid shapes, egg shapes, rugby ball shapes, etc.) or polyhydral particles (for example, soccer ball shapes, dice shapes, various brilliant cut gemstone shapes, etc.) or other such shapes close to spheres. Elongated shapes (for example, rod shapes, needle shapes, fiber shapes, etc.) or planar shapes (for example, flake shapes, plate shapes, thin slice shapes, etc.) are not suitable for the applications of the present invention since in the coating process, they align in parallel on the coating surface or settle near the interface of the substrate and coating and make it difficult to form effective conduction paths passing through the coating film in the thickness direction. [0108] The non-oxide ceramic particles (B) are not particularly limited in average particle size, but in the precoating-use composition of the present invention, they are preferably present as particles with a volume average diameter of 0.05 to 8 ~m and are more preferably present as particles with a volume average diameter of 0.2 to 5 ~m. The dispersed particles having these volume average diameters may be single particles or may be secondary particles comprised of a plurality of single particles strongly agglomerated so long as stably present in the precoating-use composition in the process of production of the precoating-use composition, at the time of storage and transport, and in the process of coating the coat-use substrate metal sheet (in the case of priming the metal surface, the primed layer). In the process of coating the • 5 10 15 20 25 30 35 - 47 - precoating-use composition on the substrate, there is no problem even if the (B) particles agglomerate along with the film formation and become larger in volume average diameter in the coating film. [0109] Note that, the "volume average diameter" referred to here means the average size, based on volume, which is found from the volume distribution data of the particles. This is because while it is possible to find this using any generally known particle size distribution measurement method, it is preferable to use the average value of the equivalent spherical diameter which is measured by the Coulter method (aperture electrical resistance method). The reason is that the Coulter method, compared with other methods of measurement of the distribution of particle size (calculation from volume distribution obtained by laser diffraction scattering method, conversion of circular area equivalent diameter distribution obtained by image analysis method to volume distribution, calculation from mass distribution obtained by centrifugal precipitation method, etc.), enables accurate, high precision measurement with almost no differences in measurement values due to the manufacturer or model of the measuring equipment. In the Coulter method, test particles are suspended in an electrolyte aqueous solution, a constant current is run through an aperture of a glass tube, and particles pass through the aperture by negative voltage. When a particle passes through the aperture, the volume of the electrolyte aqueous solution which the particle displaces (= volume of particle) causes the electrical resistance at the aperture to increase. If applying a constant current, the change in resistance at the time of passage of a particle is reflected in a change in voltage pulse, so by counting this voltage pulse height one at a time, it is possible to directly measure the volume of the individual particles. Particles are usually irregular in shape, so a sphere of a volume the same as a particle is assumed and - 48 - the size of that sphere (= equivalent spherical diameter) is converted to. The method of measurement of the equivalent spherical diameter by such a Coulter method is well known and, for example, is described in detail in 5 the web page of the official Internet site of Beckman Coulter [http://www.beckmancoulter.co.jp/product/product03/ Multisizer3.html (Precision Particle Size Distribution Measurement System Multisizer 3). 10 [0110] Non-oxide ceramic particles with a volume average diameter of less than 0.05 ~m are not only more expensive than larger non-oxide ceramic particles, but also have extremely large specific areas, so, for example, even if using a wet dispersant in a water-based 15 or organic solvent-based precoating-use composition, it is difficult to wet the particle surface and disperse the particles. Further, non-oxide ceramic particles with a volume average diameter of over 8 ~m settle faster and more easily in a water-based or organic solvent-based 20 precoating-use composition than smaller non-oxide ceramic particles (clear from Stokes equation). Therefore, sometimes it is difficult to secure stability of dispersion and particles settle, agglomerate, and solidify in a short time. 25 [0111] When defining the volume average diameter of the non-oxide ceramic particles (B) which are dispersed in the coating film (a) as "c" ~m and the thickness of the coating film (a) as "b" ~m, the relation of 0.5~c/b~1.5 is preferably satisfied. FIG. 1 is a schematic 30 view of the cross-section of the conductive, corrosion resistant precoated metal sheet of the present invention. (A) indicates an organic resin, (B), (B') indicate nonoxide ceramic particles, (C) indicates parts cross-linked by a curing agent, and (y) indicates the metal sheet. (B) 35 indicates particles with ratios c/b of particle size to thickness of 0.5 or more. In this case, conductivity in - 49 - the thickness direction is secured. (B I ) indicates particles with ratios c/b of particle size to thickness of less than 0.5. In this case, sometimes conductivity is not sufficiently secured. If the ratios c/b of particle 5 size to thickness exceed 1.5, sometimes the corrosion resistance and the workability fall. [0112] In the case of a water-based precoating-use composition, the organic resin (A) preferably contains a polyphenol 10 compound as a rust preventive agent. A polyphenol compound is a compound which has two or more phenolic hydroxyl groups bonded to a benzene ring or its condensate. It can be bonded to a metal surface by a chelation action by coordinate bonds and, further, can be 15 bonded with hydrophilic groups of a coexisting waterbased resin by hydrogen bonds. By blending in such a polyphenol compound, the adhesion between the substrate constituted by the metal sheet (in the case of priming, the primed layer) and the coating film (a) and the 20 flexibility of the coating time at the time of the sheet being worked are strikingly improved and, in turn, the corrosion resistance of the worked part is also improved. [0113] The polyphenol compound which is used in the present invention is not particularly limited so long as 25 it can be uniformly dissolved or finely dispersed in the water-based precoating-use composition which is used for forming the covering coating film. Even if not water soluble or water dispersable, it may be used so long as able to penetrate between the hydrophobic chains of the 30 resin (A1) coexisting in the water-based precoating-use composition (~) and able to uniformly finely disperse. [0114] As the compound which has two or more phenolic hydroxyl groups bonded with a benzene ring, for example, gallic acid, pyrogallol, catechol, etc. may be mentioned. 35 The condensate of the compound which has two or more phenolic hydroxyl groups bonded with a benzene ring is not particularly limited, but, for example, polyphenol • 5 10 15 20 25 30 35 - 50 - compounds etc. which are usually called tannic acid and which are widely distributed in the plant kingdom may be mentioned. "Tannic acid" is the general name for the aromatic compounds, widely distributed in the plant kingdom, of a complicated structure which have a large number of phenolic hydroxyl groups. The tannic acid may be a hydrolysable tannic acid or a condensation type tannic acid. The tannic acid is not particularly limited. For example, hamamelis tannin, persimmon tannin, tea tannin, sumac gallnut tannin, gallnut tannin, myrobalan tannin, divi divi tannin, algarovilla tannin, valonia tannin, catechin tannin, etc. may be mentioned. The polyphenol compound may be used as single types or may be used jointly as two or more types. [0115] The polyphenol compound preferably is contained in 1 to 100 parts by mass with respect to 100 parts by mass of the organic resin (A). If less than 1 part by mass, the amount of the polyphenol compound is insufficient, so a sufficient coating film adhesion cannot be obtained or as a result the worked parts may become insufficient in corrosion resistance. If over 100 parts by mass, the amount of the polyphenol compound in the coating film is too great and therefore the coating film adhesion at the time of being worked, the coating film flexibility, and the corrosion resistance of the worked parts fall or the stability of the precoating-use composition is sometimes lowered. [0116] In the case of a water-based and organic solvent-based precoating-use composition, the organic resin (A) preferably contains, as a rust preventive agent, one or more types of compounds which are selected from the group of phosphoric acid and hexafluorometal acids. These phosphoric acid and hexafluorometal acids may be used alone or may be used jointly. These acids activate the metal surface by etching and promote the action of the silane coupling agent (s) or the polyphenol compound on the metal surface. Further, phosphoric acid • 5 10 15 20 25 30 35 - 51 - has, in addition to the above action, the action of forming a phosphate layer on a metal surface so as to passivate it, so improves the corrosion resistance. Further, hexafluorometal acids, in addition to the above action, enable the formation of a stable thin film containing oxides of a metal supplied from hexafluorometal acids on the metal surface on which the coating film is formed and, as a result, improves the corrosion resistance. The phosphoric acid which can be used in the present invention is not particularly limited. For example, o-phosphoric acid, p-phosphoric acid (linear polymer of polymerization degree of 0phosphoric acid of up to 6 alone or mixture of two or more types of these), or m-phosphoric acid (cyclic polymer of polymerization degree of o-phosphoric acid of 3 to 6 alone or a mixture of two or more types of these) may be mentioned. The phosphoric acid may be used in single types or may be jointly used as two or more types. A polyphosphoric acid with a polymerization degree larger than 2 can be easily industrially obtained as a mixture of polyphosphoric acids with several polymerization degrees, so in the present invention, such a mixture may be used. [0117] The hexafluorometal acids which can be used in the present invention are not particularly limited. For example, hexafluoro- phosphoric acid, hexafluorotitanic acid, hexafluorozirconic acid, hexafluorosilicic acid, hexafluoroniobic acid, hexafluoroantimonic acid, or their ammonium salts, potassium salts, sodium salts, calcium salts, magnesium salts, etc. may be mentioned. Hexafluorometal acids, in the above way, form stable thin films which contain metal oxides on metal surfaces, but to give rise to such effects, preferably include as the metals one or two or more elements which are selected from the group comprised of Ti, Si, Zr, and Nb. The hexafluorometal acids may be used as single types or may be jointly used as two or more types. • 5 10 15 20 25 30 35 - 52 - [0118] One or more acids selected from the group of phosphoric acid and hexafluorometal acids are preferably contained in 0.1 to 100 parts by mass with respect to 100 parts by mass of the organic resin (A). If less than 0.1 part by mass, the action by these acids will be insufficient, so the corrosion resistance will sometimes drop. If over 100 parts by mass, the coating film will become fragile and cohesive failure of the coating film may cause the coating film adhesion when being worked and the flexibility of the coating film to drop. [0119] In the case of a water-based and organic solvent-based precoating-use composition, the organic resin (A) preferably contains a phosphate compound as a rust preventive agent. By blending in this phosphate compound, when forming a coating film, an insoluble phosphate thin film can be formed on the metal surface. That is, if the melt dissolves due to the phosphoric acid ions of the phosphate, the pH will rise at the metal surface and, as a result, a settled film of the phosphate will be formed and the corrosion resistance will be improved. [0120] The phosphate compound which can be used in the present invention is not particularly limited. For example, o-phosphoric acid, p-phosphoric acid (linear polymer of o-phosphoric acid up to polymerization degree 6 alone or mixture of two or more types of the same), mphosphoric acid (cyclic polymer of o-phosphoric acid up to polymerization degree 3 to 6 alone or mixture of two or more types of the same), or other metal salts, phytic acid, phosphonic acid, phosphinic acid, and other organic metal salts may be mentioned. The type of cation is not particularly limited. For example, Cu, Co, Fe, Mn, Sn, V, Mg, Ba, Al, Ca, Sr, Nb, Y, Ni, Zn, etc. may be mentioned, but Mg, Mn, Al, Ca, and Ni are preferably used. The phosphate compound may be used alone as single types or may be jointly used as two or more types. [0121] The phosphate compound is preferably contained - 53 - in 0.1 to 100 parts by mass with respect to 100 parts by mass of the organic resin (A). If less than 0.1 part by mass, the action of the phosphate compound is insufficient, so the corrosion resistance sometimes 5 falls. If over 100 part by mass, the coating film becomes fragile and cohesive failure of the coating film sometimes cause the coating film adhesion when worked and the coating film flexibility to fall. [0122] In the case of a water-based and organic 10 solvent-based precoating-use composition, the organic resin (A) preferably contains, as a rust preventive agent, metal oxide particles comprised of at least one type of metal element selected from the group of Si, Ti, AI, and Zr. By blending in these metal oxide particles, 15 the corrosion resistance can be enhanced more. [0123] As the metal oxide particles which can be used in the present invention, for example, silica particles, alumina particles, titania particles, zirconia particles, etc. may be mentioned. Ones with a volume average 20 diameter of 1 to 300 nm or so are preferable. These may be used alone or may be jointly used in two or more types. Among these, silica particles are added when both improvement of the corrosion resistance of the coating and strengthening and toughening are required. The silica 25 particles are not particularly limited, but the coating film is a thin film, so primary particle size 3 to 50 nm colloidal silica, fumed silica, or other silica particles are preferred. [0124] The metal oxide particles are preferably 30 contained in 1 to 100 parts by mass with respect to 100 parts by mass of the organic resin (A). If less than 1 part by mass, the amount of the metal oxide particles is insufficient, so sometimes the effect of raising the corrosion resistance cannot be obtained. If over 100 35 parts by mass, the coating film becomes fragile and coating film cohesive failure sometimes causes a drop in the coating film adhesion at the time of working and the • 5 10 15 20 25 30 35 - 54 - flexibility of the coating film. [0125] The above various types of rust preventive agents are preferably dissolved or dispersed and stabilized in suitable amounts in the precoating-use composition (p) and introduced into the organic resin (A) in the coating film (a) in advance. [0126] The coating film (a) may further contain a coloring pigment. The type of the coloring pigment is not particularly limited. As an inorganic coloring pigment, for example, titanium dioxide powder, alumina powder, Venetian Red, Burnt Sienna, and other iron oxide powder, zinc oxide powder, carbon black, graphite powder, coal dust, talc powder, Cadmium Yellow, Cadmium Red, Chrome Yellow, Cobalt Yellow, Cobalt Blue, Cerulean Blue, Cobalt Green, etc. may be used. As the organic coloring pigment, for example, Phthalocyanine Blue, Phthalocyanine Green, quinacridone, perylene, anthrapyrimidine, Carbazole Violet, anthrapyridine, Azo Orange, Flavanthrone Yellow, Isoindoline Yellow, Azo Yellow, Indanthrone Blue, Dibromanzathrone Red, Perylene Red, Azo Red, Anthraquinone Red, etc. may be used. Further, if able to give the coating film (a) the necessary coloring or gloss, feeling, and other appearance, for example, copper powder, tin powder, nickel powder, bronze (Cu-Sn-based alloy) powder, or other water resistant metal particles may be used as coloring pigments. Even aluminum powder or zinc powder etc. which are somewhat inferior in water resistance can be used as coloring pigments. Further, aluminum flakes, mica flakes, sheet-like iron oxide, glass flakes, and other flake-like bright materials, mica powder, metal coating mica powder, titanium dioxide coated mica powder, titanium dioxide coated glass powder, or other powdered bright materials can also be used. [0127]