JP2011136566A - Clear-coated stainless steel plate and its manufacturing process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clear-coated stainless steel plate which is fitted to surroundings, and has a high function such as high gloss, scratch resistance, fingerprint stain resistance, high productivity, and inverdal tone design property, and to provide a method of manufacturing the same. <P>SOLUTION: In the clear-coated stainless steel plate, a chemically treated coating film comprises one or two kinds of aminosilane type film and epoxysilane type film, in the attachment amount of 2-50 mg/m<SP>2</SP>. The clear coating film comprises a thermosetting resin composition containing an acryl resin having a cross-linking functional group as a main component and a block isocyanate compound for crosslinking and curing the acryl resin, the thickness of the clear coating film being 1-10 μm. The acrylic resin can contain a polyolefin-based wax, an amino resin, an organosilica sol, and an amorphous silica. The acrylic resin also contains a curing catalyst for the amino resin and acrylic resin beads. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is applied to parts such as home appliances, building materials, automobiles, etc. whose chemical conversion treatment is non-chromium treatment, non-polluting, and excellent in adhesion, pressability, weather resistance, rain-stain contamination, detergent resistance, and chemical resistance. The present invention relates to a clear lubricated coated stainless steel sheet and a method for producing the same. Furthermore, the present invention relates to a highly functional clear lubricated coated stainless steel sheet excellent in high gloss, fingerprint stain resistance or wrinkle resistance, and further to a highly designed clear coated stainless steel sheet.

  When press forming a plate material such as a stainless steel plate, the forming is performed after applying a lubricating oil, and the lubricating oil is dropped using a solvent or alkaline degreasing after the forming. The use of these lubricants deteriorates the press environment, and chlorofluorocarbons and organic solvents that have been used as degreasing solvents destroy the ozone layer. . As described above, the use of lubricating oil has further problems of waste liquid treatment and working environment, and there is a demand for a clear lubricated stainless steel plate that is environmentally friendly and can be press-formed without oil coating and can be degreased. On the other hand, when a stainless clear steel plate is used for home appliances and the like, a chromate-free clear lubricated stainless steel plate is required due to problems such as sick house syndrome. Further, regarding building material products, there is a demand for a clear lubricated stainless steel plate that has excellent weather resistance, rain line contamination, and acid rain resistance.

  However, as a stainless clear lubricating steel plate excellent in press formability, for example, as disclosed in Patent Document 1, a coating chromate treatment is performed, and an ether- and ester-type urethane resin having an epoxy-modified polyester resin, a bisphenol-type skeleton, an ester skeleton, and a carboxyl group. In addition, a stainless steel clear lubricating steel plate with excellent pressability is used by thermosetting acrylic resin with melamine resin, etc., and dispersing polyolefin wax in the coating film, but because it contains a bisphenol type skeleton, weather resistance is inferior, The use is limited, and the chromate treatment contains a slight amount of hexavalent chromium, but causes problems such as sick house syndrome.

  Due to the above-mentioned problems of environmental regulations in recent years, metal surface treatments are being replaced by non-chromate treatments from chromium-based surface treatment agents such as chromate treatment and phosphate chromate treatment. However, adhesion and corrosion resistance are worse than chromate treatment and phosphoric acid chromate treatment. Therefore, silane coupling and water-dispersible silica are added to the treatment liquid to maintain adhesion and corrosion resistance (Patent Document 2). However, the silane coupling agent does not adversely affect the gloss of the clear coating film applied as a protective agent, but there is a problem that the gloss is deteriorated although the corrosion resistance increases as water-dispersible silica is added. In particular, the tendency of the stainless clear steel sheet is prominent, and the development of a clear coated stainless steel sheet capable of obtaining high gloss by non-chromate processing is desired.

  Clear coated stainless steel sheet has a high-grade appearance that makes use of metallic luster and has a very high surface luster, so there are an increasing number of cases used for housing, interior materials, and cover materials of home appliances. . A clear coating stainless steel sheet is made of a clear paint such as polyester resin, acrylic resin, silicone polyester resin, acrylic silicone resin, or fluororesin, and is coated with 1 coat 1 bake or 2 coat 2 bake. The clear coated stainless steel plate has poor adhesion because it is made of a stainless steel plate with an inert surface, and the bright annealed (BA) finished stainless steel plate has a dense passivity, making it more difficult to adhere. is there. In addition, the clear coated stainless steel sheet used for the housing, interior material, and cover material of home appliances is characterized by a very high surface gloss. At present, a clear coated stainless steel sheet having a good balance between scratch resistance and workability and excellent workability has not yet been developed. As a clear-coated stainless steel plate with excellent scratch resistance and workability, for example, as described in Patent Document 3, a 2-coat 2-bake system is used for the undercoat to form a high-thickness film with a low-elasticity coating film, and for a top-coating, a high-elasticity coating film The production method of clear coated stainless steel sheet with improved workability and scratch resistance by adjusting to a low film thickness has been reported, but it must be a coating process of 2 coats and 2 bake, as well as undercoating and overcoating Therefore, it is necessary to distinguish the coating materials and control the film thickness, and it is necessary to control the coating thickness.

  As mentioned above, the clear-coated stainless steel sheet used for the housing, interior material, and cover material of home appliances is characterized by a very high surface gloss. Contamination is conspicuous. Currently, a clear-coated stainless steel sheet considering such resistance to fingerprint contamination has not been developed yet.

  Clear coated stainless steel sheets used for housings, interior materials, and cover materials of home appliances generally have a very high surface gloss. It is requested. However, simply lowering the gloss does not give a sense of luxury, and it is not possible to handle calm household appliances. The invaral steel plate is a stainless steel plate having a special anti-glare property and a design property, using a special roll and having fine irregularities on the plate surface.

JP 2001-149860 A JP 2001-316845 A JP 2003-15439 A

  The first object of the present invention is an environment-friendly clear-coated stainless steel plate that is chromate-free and has excellent clearability, weather resistance, rain-stain contamination, scratch resistance, detergent resistance, and chemical resistance, and its It is to establish a manufacturing method.

  The second problem is to provide a high-gloss coated stainless steel clear steel plate and a method for producing the same.

  A third problem is to provide a high-performance clear-coated stainless steel sheet having a good balance between scratch resistance and workability, excellent workability, and capable of being baked in a short time, and a method for producing the same.

  The fourth problem is to provide a highly functional clear-coated stainless steel sheet excellent in fingerprint resistance and a method for producing the same.

  The fifth problem is to provide an invaral clear-coated stainless steel sheet having a low gloss and a high-class feeling and a method for producing the same.

  As a result of earnestly examining the means for solving the above problems, the present inventors have studied the characteristics of the thermosetting resin, wax, chemical conversion treatment agent and coating conditions, and established an environment-friendly clear lubricated stainless steel sheet and a method for producing the same. did.

That is, the gist of the present invention is as follows.
(1) In a clear-coated stainless steel sheet in which the upper layer is formed of a clear coating film and the lower layer is formed of a chemical conversion coating film, the chemical conversion coating film is substantially composed of one or two types of aminosilane-based and epoxysilane-based chemical conversion processing. The acrylic resin is composed mainly of an acrylic resin having a coating amount of ² to 50 mg / m ² , a glass transition point of 30 to 90 ° C. and a number average molecular weight of 3000 to 50000. A clear-coated stainless steel sheet, which is a thermosetting resin composition containing a blocked isocyanate compound for crosslinking and curing, and has a clear coating film thickness of 1 to 10 μm.
(2) The clear coating film contains 0.25 to 5 parts by mass of a polyolefin wax in solid content per 100 parts by mass of the solid material of the thermosetting resin composition. Clear painted stainless steel sheet.
(3) The clear conversion coating described in (1) or (2) above, wherein the chemical conversion coating film contains 0.1 to 30% (solid content ratio) of chain-like water-dispersible silica. Painted stainless steel sheet.
(4) The thermosetting resin composition contains an amino resin as a resin for cross-linking and curing the acrylic resin. Clear-coated stainless steel sheet.
(5) The thermosetting resin composition is a composition containing 2 to 10 parts by mass of an organosilica sol per 100 parts by mass of the solid matter. Clear steel stainless steel sheet as described.
(6) The thermosetting resin composition contains 0.5 to 5 parts by mass of amorphous silica per 100 parts by mass of the solid, and has excellent anti-fingerprint resistance and scratch resistance The clear coated stainless steel sheet according to any one of (2) to (5).
(7) The thermosetting resin composition contains 0.5 to 5 parts by mass of a P-toluenesulfonic acid catalyst as a curing catalyst for the amino resin per 100 parts by mass of the solid material of the thermosetting resin composition. The clear coated stainless steel sheet according to any one of the above (4) to (6), which is excellent in productivity, fingerprint resistance, and wrinkle resistance.
(8) The clear coated stainless steel according to the above (7), wherein the thermosetting resin composition contains a curing catalyst for the blocked isocyanate resin and is excellent in productivity, fingerprint resistance and wrinkle resistance steel sheet.
(9) The thermosetting resin composition contains 0.5 to 8 parts by mass of acrylic resin beads per 100 parts by mass of the solid material, and has an invaral design as described in (4) above Clear-coated stainless steel sheet.
(10) A method for producing a stainless steel plate in which the upper layer is formed of a clear coating film and the lower layer is formed of a chemical conversion coating film, and the amount of adhesion of the chemical conversion coating film consisting of one or two types of aminosilane type and epoxysilane type the coating is 2 to 50 mg / m ^2, then the glass transition point having a crosslinkable functional group as a clear coating film is 30 to 90 ° C., the acrylic resin acrylic resin having a number average molecular weight of 3,000 to 50,000 as a main component A method for producing a clear-coated stainless steel sheet, comprising applying a thermosetting resin composition containing a blocked isocyanate compound for crosslinking and curing so that a clear coating film thickness is 1 to 10 μm.
(11) The clear-coated stainless steel as described in (10) above, wherein the thermosetting resin composition contains 0.25 to 5 parts by mass of a solid content of polyolefin wax per 100 parts by mass of the solid. A method of manufacturing a steel sheet.
(12) The clear conversion coating according to (10) or (11) above, wherein the chemical conversion coating film contains 0.1 to 30% (solid content ratio) of chain-like water-dispersible silica and has high gloss. Manufacturing method of painted stainless steel sheet.
(13) The thermosetting resin composition contains an amino resin as a resin for crosslinking and curing the acrylic resin, and is described in any one of the above (11) to (12), which has excellent scratch resistance Method of clear-coated stainless steel sheet.
(14) The thermosetting resin composition is a composition containing 2 to 10 parts by mass of an organosilica sol per 100 parts by mass of the solid matter. The manufacturing method of the clear coating stainless steel plate of description.
(15) The thermosetting resin composition contains 0.5 to 5 parts by mass of amorphous silica per 100 parts by mass of the solid, and has excellent anti-fingerprint resistance and scratch resistance The manufacturing method of the clear coated stainless steel plate as described in (11)-(14).
(16) The thermosetting resin composition contains 0.5 to 5 parts by mass of a P-toluenesulfonic acid-based catalyst as a curing catalyst for the amino resin per 100 parts by mass of the solid material of the thermosetting resin composition. The method for producing a clear-coated stainless steel sheet according to any one of the above (13) to (15), which is excellent in productivity, fingerprint resistance and wrinkle resistance.
(17) The clear-coated stainless steel according to the above (16), wherein the thermosetting resin composition contains a curing catalyst for the blocked isocyanate resin and is excellent in productivity, fingerprint resistance and wrinkle resistance A method of manufacturing a steel sheet.
(18) The thermosetting resin composition contains 0.5 to 8 parts by mass of acrylic resin beads per 100 parts by mass of the solid, and has an invaral design as described in (13) above Method of clear-coated stainless steel sheet.

  According to the present invention, there is obtained an environment-friendly stainless steel clear lubricated steel plate that is chromate-free, non-polluting, and has excellent clearability, weather resistance, rain-stain contamination, scratch resistance, detergent resistance, and chemical resistance. be able to. Furthermore, according to the present invention, a clear-coated stainless steel plate having high gloss, a clear-coated stainless steel plate excellent in fingerprint stain resistance and scratch resistance, a clear-coated stainless steel plate excellent in productivity that enables short-time baking, or A clear-coated stainless steel sheet having excellent invaral design can be obtained. Therefore, it is possible to provide a stainless steel clear lubricating steel plate that is optimal not only for home appliances and building material interior materials but also for building material exteriors.

The clear-coated stainless steel sheet of the present invention has a chemical conversion coating film of one or two types of aminosilane type and epoxysilane type, a chemical conversion coating film adhesion amount of ² to 50 mg / m ² , and the clear coating film is crosslinked. A glass transition point having a functional functional group is 30 to 90 ° C., and a thermosetting resin composition containing a blocked isocyanate compound for crosslinking and curing the acrylic resin with an acrylic resin having a number average molecular weight of 3000 to 50000 as a main component, The clear coating thickness is 1 to 10 μm.

Moreover, the manufacturing method of the clear coated stainless steel plate of this invention apply | coats the chemical conversion coating film which consists of one type or two types of aminosilane type | system | group, an epoxysilane type | system | group so that an adhesion amount may be 2-50 mg / m < ² >, and is then clear. Thermosetting resin composition comprising a blocked isocyanate compound for crosslinking and curing the acrylic resin having an acrylic resin having a glass transition point of 30 to 90 ° C. and a number average molecular weight of 3000 to 50000 as a main component. The object is applied so that the clear coating film thickness is 1 to 10 μm.

  By adopting the above configuration, the present invention is an environment-friendly stainless steel that is chromate-free, non-polluting, and has excellent clearing properties, weather resistance, rain-stain contamination properties, scratch resistance, detergent resistance, and chemical resistance. A clear lubricated steel sheet can be obtained. In the present invention, the scratch resistance is a simple indicator of the hardness of the clear-coated steel sheet surface.

The chemical conversion coating film in the present invention is composed of one or two types of aminosilane type and epoxysilane type, and is applied so that the adhesion amount is ² to 50 mg / m ^2, and the surface temperature (MT) of the stainless steel plate material is Bake and dry at 60-140 ° C. When the adhesion amount of the chemical conversion coating film is less than 2 mg / m ² , the gloss is deteriorated and the corrosion resistance is also deteriorated. When the adhesion amount exceeds 50 mg / m ² , the water-soluble component of the chemical conversion treatment increases and blisters are generated on the surface of the coating film after the boiling water test. Preferably the upper limit is at 30 mg / m ^2, more preferably from 2 to 10 mg / m ^2. The adhesion amount of the chemical conversion coating film can be determined by measuring the SiO ₂ amount with fluorescent X-rays.

  Examples of aminosilane coupling agents include N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, and 3-aminopropyltrimethoxysilane, and epoxy. Examples of the silane coupling agent include silane coupling agents such as 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane. In addition, one or two of these materials can be substantially used, and polyethylene wax or silica-based aggregate can be mixed.

  The treatment liquid can be applied using a method such as spraying, roll coater, curtain flow coating, electrostatic coating or the like.

  Drying may be performed by evaporating moisture, and the temperature is suitably 60 to 140 ° C. In this treatment, a known pretreatment such as alkali degreasing, acid or alkali etching may be performed as necessary.

  Any non-chromate metal surface treating agent for forming the chemical conversion coating film can be used as long as it is commercially available. Commercially available non-chromate metal surface treatment agents include Palcoat E305, 3750, 3751, 3753, 3756, 3757, 3970 (manufactured by Nihon Parkerizing Co., Ltd.), Alsurf 440 (manufactured by Nippon Paint Co., Ltd.) and the like.

  Conventionally, the chromate treatment as a metal surface treatment is slight but contains hexavalent chromium, which is harmful, and when the chromium treatment is used as a chemical conversion treatment, the stainless steel surface is slightly yellowish. When the non-chromate chemical conversion coating film of the present invention is used, it is colorless and transparent, and the coating film of claims 1 and 2 of the present invention is applied in an amount of 1 to 10 μm. By baking, a stainless clear lubricating steel plate having high whiteness can be obtained, and at the same time, a stainless clear lubricating steel plate excellent in weather resistance and rain-stain contamination required as a building material product can be obtained. The reason for the excellent resistance to rain streak contamination is not clear, but trace amounts of water-soluble components in the chemical conversion coating film are oriented on the surface of the coating film, while the surface hardness of the coating film is high. Even if it adheres, it hardly penetrates into the inside of the coating film, and it is thought that it is excellent in rain line contamination because it flows with a water-soluble component oriented on the coating film surface. Furthermore, when a chemical conversion treatment film in which chain-like water-dispersed silica is blended with a non-chromate metal surface treatment agent is used, a very high gloss clear coated stainless steel sheet can be obtained.

  The clear coating film in the present invention is a thermosetting resin composition mainly composed of an acrylic resin having one or two or more crosslinkable functional groups selected from a hydroxyl group, a carboxyl group, an alkoxysilane group and the like. The acrylic resin can be obtained by a manufacturing method known as a coating resin.

  Examples of the acrylic resin include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. , Aliphatic or cyclic acrylates such as n-hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl methacrylate, and the like can be used. These are methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ethers. Styrenes such as styrene and a-methylstyrene. One type or two or more types of non-functional monomers selected from acrylamide monomers such as acrylamide, N-methylol acrylamide, diacetone acrylamide, etc., and a crosslinkable functional group such as hydroxyl group, carboxyl group, alkoxysilane group, etc. It can be obtained by reacting with one or two or more kinds of polymerizable monomers.

  Monomers each containing one or more hydroxyl groups and polymerizable unsaturated double bonds in one molecule include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate. And hydroxyalkyl esters such as Plaxel FM1-5, FA-1-5 (manufactured by Daicel Chemical Industries), and lactone-modified hydroxyl group-containing vinyl polymerization monomers.

  A polymer monomer having a carboxyl group is a compound containing at least one carboxyl group and one polymerizable unsaturated double bond in one molecule, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid. An acid etc. can be mentioned.

  The polymer monomer having an alkoxysilane group is a compound containing at least one alkoxysilane group and one polymerizable unsaturated double bond in one molecule. For example, vinyltrimethoxysilane, vinyltriethoxysilane, Examples include acryloxypropyltrimethoxysilane.

  As described above, the acrylic resin has a crosslinkable functional group such as a hydroxyl group, a carboxyl group, and an alkoxysilane group. Here, the acrylic resin can have two or more crosslinkable functional groups per molecule. Further, the glass transition point of the resin is suitably 30 to 90 ° C, and more preferably within the range of 50 to 90 ° C. When the glass transition point of the resin is less than 30 ° C., the temperature of the steel sheet surface rises to 80 to 100 ° C. due to friction and heat generated during continuous pressing, resulting in softening of the coating film. Resin adheres. On the other hand, when the temperature exceeds 90 ° C., workability during painting such as pinholes and insufficient leveling is poor. The number average molecular weight of the acrylic resin is suitably in the range of 3000 to 50000 acrylic resin, particularly in the range of 4000 to 10,000. If it is less than 3000, the reactivity with the crosslinking agent is too poor to form a coating film, and if it exceeds 50000, the solubility in the solvent is insufficient and the resin liquid is not formed. The number average molecular weight of the acrylic resin is linked to the glass transition point of the resin, and by setting the molecular weight within the above range, the glass transition point can be set within the above preferable range.

  The crosslinking agent, which is another component of the acrylic resin-based thermosetting resin component, is a blocked isocyanate resin.

  A blocked isocyanate compound is a compound having two or more isocyanate groups in one molecule, and is an aliphatic diisocyanate such as tolylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, naphthalene diisocyanate, aliphatic such as hexamethylene diisocyanate, dimer acid diisocyanate. Diisocyanate, isophorone diisocyanate, cycloaliphatic diisocyanate and other alicyclic diisocyanates, burette type adducts of the polyisocyanates, isocyanuric ring type adducts, etc., and these polyisocyanates are phenols, oximes, active methylenes, ε -Blocked with a blocking agent such as caprolactams, triazoles, pyrazoles, and dibutyltin dilauri Organotin catalyst is used as a dissociation promoters of blocking agent over bets like. As a commercial product, Death Module BL1100, BL1265MPA / X, VPLS2253, BL3475BS / SN, BL3272MPA, BL3370MPA, BL4265SN, Desmosum 2170, Sumijour 3175 (above, manufactured by Sumika Bayer Urethane Co., Ltd.) Duranate 17B-60PX, TPA-B80X , MF-B60X, MF-K60X (above, manufactured by Asahi Kasei Kogyo Co., Ltd.) Bernock DB-980K, D-550, B3-867, B7-887-60 (above, manufactured by Dainippon Ink Industries, Ltd.), Coronate 2515, 2507, 2513 (manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like may be used alone or in combination.

  The composition ratio of both the resin and the crosslinking agent in the acrylic resin-based thermosetting resin composition can be varied over a wide range according to the purpose, and the isocyanate group is contained in 1 mol of (OH + COOH) group in the acrylic resin. It is good to set it as 0.1-2.0 mol. The amount is preferably 0.1 to 1.0, more preferably 0.2 to 0.8 mol. The terminal and side chain in one molecule of the base resin can be selected from a hydroxyl group, a carboxyl group, an alkoxysilane group, and the like. The constituent ratios of both the resin and the crosslinking agent in the acrylic resin thermosetting resin composition can be varied over a wide range depending on the purpose.

  In addition, leveling agents, antifoaming agents, antioxidants, UV absorbers, matting agents, silane coupling agents, etc., may be mixed into the clear coating film as additives to make a paint, or pigments or dyes may be dispersed. It is also possible to use color clear. Moreover, you may contain an epoxy resin, a silicon resin, a fluororesin, a polyester resin, etc. as needed.

  The clear coating film of the present invention is also characterized by containing 0.25 to 5.0 parts by mass of a polyolefin wax in a solid content per 100 parts by mass of the solid material of the thermosetting resin composition. Thereby, the clear coating stainless steel plate excellent in the lubricity which has the moldability superior to the stainless steel plate which apply | coated the oil-based lubricant etc. can be obtained.

  Examples of the polyolefin wax include hydrocarbon waxes such as paraffin, microclostaline, polyethylene, and polyethylene-fluorine. At the time of processing, the coating temperature rises due to processing heat generation and frictional heat of the material, so the melting point of the wax is suitably 70 to 160 ° C. If it is less than 70 ° C., it softens and melts during processing and has excellent properties as a solid lubricant additive However, when the temperature exceeds 160 ° C., the hard particles are present on the surface, so that the frictional characteristics are deteriorated, so that high moldability cannot be obtained.

  The acid value of the polyolefin wax is desirably 0 to 30, and if it exceeds 30, the compatibility with the resin is improved, and the wax does not uniformly float on the surface of the coating film, resulting in insufficient processability.

  A suitable particle size of these waxes is 0.1 to 7.0 μm. Those exceeding 7.0 μm are not preferable because the distribution of the solidified wax becomes non-uniform. Moreover, when it is less than 0.1 μm, workability is insufficient. The amount of the polyolefin wax is suitably 0.25 to 5.0 parts by mass per 100 parts by mass of the solid material of the thermosetting resin composition. If it is less than 0.25 parts by mass, the workability is insufficient, and if it exceeds 5.0 parts by mass, unevenness occurs on the surface of the coating film and the appearance of the clear steel plate is impaired.

  The chemical conversion coating film of the present invention preferably contains 0.1 to 30% (solid content ratio) of chain water-dispersible silica. A clear-coated stainless steel sheet having high gloss can be obtained by forming a chemical conversion coating film with a treatment liquid in which chain-like water-dispersible silica is blended and then applying a clear paint.

  The chain water-dispersible silica blended in the chemical conversion coating film of the present invention can be used as long as it has a small sodium content. Suitable products include “Snowtex UP” and “Snowtex OUP” (manufactured by Nissan Chemical Industries, Ltd.). As the water-dispersible silica, there is spherical water-dispersible silica in addition to the chain water-dispersible silica, but high gloss cannot be obtained. The reason why chain water-dispersible silica is suitable is not clear, but it can be cited that it has good film-forming properties, good bonding properties, high viscosity, and high film-forming gel properties.

  The content of the chain water-dispersible silica is 0.1 to 30% (solid content ratio) in the metal surface treatment agent, preferably 0.5 to 25% (solid content ratio). When the amount of the chain water-dispersible silica is less than 0.1% (solid content ratio), the effect of improving the glossiness is insufficient, and when it exceeds 30% (solid content ratio), the stability of the treatment liquid is deteriorated.

  The chemical conversion coating film of the present invention has a phosphoric acid salt such as phosphates, condensed phosphoric acid, polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid or salts thereof, acrylic resin, urethane resin, epoxy resin, phenol to further increase the corrosion resistance. A water-soluble resin such as a resin, a polyester resin, a polyolefin resin, or an alkyd resin may be used in combination.

  In addition to the blocked isocyanate resin, it is preferable to use an amino resin as a crosslinking agent that is another constituent of the thermosetting resin composition of the present invention. By applying a clear paint containing an amino resin (melamine resin) as a resin for crosslinking and curing the thermosetting resin composition, a clear coated stainless steel sheet having excellent scratch resistance can be obtained.

  Amino resin is a generic term for resins modified with alcohol by addition reaction of amino compounds (melamine, guanamine, urea) and formaldehyde (formalin), and melamine resin, benzoguanamine resin, urea resin, butylated urea resin, There are butylated urea melamine resin, glycoluril resin, acetoguanamine resin, and cyclohexylguanamine resin. Among them, melamine resin is preferable from the viewpoint of fingerprint resistance, scratch resistance and chemical resistance due to thermosetting. Depending on the type of alcohol to be modified, it is divided into methylated melamine resin, n-butylated melamine resin, isobutylated melamine resin, mixed alkylated melamine resin and the like. Examples of methylated melamine resins include Cymel 300, 301, 303, 350, 370, 771, 325, 327, 703, 712, 715, 701, 267, 285, 232, 235, 236, 238, 211, 254, 204, 212, 202, 207 (Mitsui Cytec Co., Ltd.), LUWIPAL 063, 066, 068, 069, 072, 073 (BASF), Super Becamine L-105 (Made by Dainippon Ink & Chemicals, Inc.) ) Melan 522, 523, 620, 622, 623 (above, manufactured by Hitachi Chemical Co., Ltd.), Mycoat 506, 508 (above, manufactured by Mitsui Cytec Co., Ltd.), Uban 20SB, 20SE, 21R, 22R, 122, 125, 128, 220, 225 228, 28-60, 20HS, 2020, 2021, 2028, 120 (above, manufactured by Mitsui Chemicals), PLASTOPAL EBS 100A, 100B, 400B, 600B, CB (above, manufactured by BASF) Super Becamine J-820, L-109, L-117, L-127, L-164 (above, Dainippon Ink & Chemicals, Inc.), Melan 21A, 22, 220, 2000, 8000 (above, made by Hitachi Chemical Co., Ltd.), Tesazine 3020, 3021, 3036 (manufactured by Hitachi Chemical Co., Ltd.) and isobutylated melamine resins are Uban 60R, 62, 62E, 360, 361, 165, 166-60, 169, 2061 (manufactured by Mitsui Chemicals, Inc.) ), Superbecamine G-821, L-145, L-110, L- 125 (above, Dainippon Ink & Chemicals, Inc.), PLASTOPAL EBS 4001, FIB, H731B, LR8824 (above, made by BASF) Melan 27, 28, 28D, 245, 265, 269, 289 (above, Hitachi Chemical Co., Ltd.) Manufactured by company), Tesazine 3027, 3028, 3029, 3030, 3037 (manufactured by Hitachi Chemical Co., Ltd.), and mixed alkylated melamine resins include Cymel 267, 285, 232, 235, 236, 238, 211, 254, 204 212, 202, 207 (Mitsui Cytec Co., Ltd.) and the like may be used alone or in combination.

  The content of the amino resin in the thermosetting resin composition is 10 to 40 parts by mass, preferably 15 to 30 parts by mass with respect to 100 parts by mass of the acrylic resin solid content.

  In the thermosetting resin composition of the present invention, the organosilica sol is 2.0 to 10 parts by mass and the amorphous silica is 0.5 to 5.0 parts by mass per 100 parts by mass of the thermosetting resin composition. Part can be selectively contained. By applying a clear paint containing an organosilica sol in the thermosetting resin composition, a clear-coated stainless steel sheet having excellent scratch resistance can be obtained. Furthermore, by applying a clear paint containing amorphous silica in the thermosetting resin composition, a clear-coated stainless steel sheet having excellent fingerprint stain resistance in addition to scratch resistance can be obtained.

  Organosilica sol is a colloidal solution in which nanometer (nm) level colloidal silica is stably dispersed in an organic solvent, and has the performance of a ceramic. By containing it, the hardness of the coating film, resistance to wrinkles, Improves fingerprint resistance. MA-ST-M, IPA-ST, EG-ST, EG-ZL, NPC-ST, DMAC-ST, DMAC-ST-ZL, XBA-ST, MIBK-ST depending on the type of solvent and solid content of the dispersion medium (The above is manufactured by Nissan Chemical Industries, Ltd.) and the like, and may be selected as a single product or in combination depending on the compatibility with the acrylic resin. The content of 2.0 to 10 parts by mass is preferable per 100 parts by mass of the thermosetting resin composition, but 3 to 8 parts by mass is more preferable. If it is less than 2.0 parts by mass, the scratch resistance and hardness are insufficient, and if it exceeds 10 parts by mass, the workability deteriorates.

  Amorphous silica is a fluid powder having porosity, and many types thereof are commercially available due to differences in average particle diameter, pore volume, pore diameter, and surface treatment. This is presumed to be due to the porosity and the surface being covered with a hydroxyl group having a strong affinity for water. Specifically, Silysia 250, 250N, 256, 256N, 310P, 320, 350, 370, 380, 420, 430, 440, 450, 470, 435, 445, 436, 446, 456, 476, 530, 550, 710 730, 740, 770, 780 (Fuji Silysia Chemical Co., Ltd.), Mizukacil P-801, P-802, P-526, P-527, P-603, P-604, P-554A, P- 73, P-78A, P-78D, P-78F, P-707, P-740, P-752, P-50, P-766 (Made by Mizusawa Chemical Co., Ltd.) Carplex FPS-1, FPS -2, FPS-3, FPS-4, FPS-5, FPS-101, CS-5, CS-7, CS-8, CS-701, CS-801 (manufactured by Shionogi) Is like Co., Ltd.), it may be selected individually or in combination. The content of 0.5 to 5.0 parts by mass is preferable per 100 parts by mass of the thermosetting resin composition, but 1.0 to 4.0 parts by mass is more preferable. If it is less than 0.5 parts by mass, the antifouling resistance to fingerprints is lowered, fingerprints are easily attached when directly touching the coating film, and wiping with gauze is not easy. If it exceeds 5.0 parts by mass, the effect of resistance to fingerprint contamination is maintained, but the gloss of the coating film becomes too low, and the high-quality feeling of the clear coated stainless steel sheet is lost.

  The thermosetting resin composition contains an amino resin as a resin for crosslinking and curing the acrylic resin, thereby increasing the hardness of the clear coating film and improving the scratch resistance. On the other hand, when the amino resin is used, the thermosetting resin is thermoset. The time required for the functional resin composition to cure becomes longer. Therefore, when an amino resin is used, it is necessary to lengthen the time required for baking the clear coating film, and it is necessary to reduce the productivity of the coating line.

  In the thermosetting resin composition of the present invention containing an amino resin, it is preferable to include a curing catalyst for the amino resin in order to accelerate the curing of the clear coating film because the resin can be cured in a short baking time.

  In general, a sulfonic acid-based or amine-based catalyst is used as a curing catalyst for an amino resin. Among the sulfonic acid-based catalysts, a P-toluenesulfonic acid-based catalyst is used for the purpose of enabling short-time baking, which is a feature of this patent. It is desirable to contain 0.5 to 5 parts by mass, preferably 1 to 2 parts by mass in terms of solid content per 100 parts by mass of the thermosetting resin composition and 100 parts by mass of the crosslinked resin composition. If the amount is less than 0.5 parts by mass, the effect cannot be obtained. If the amount exceeds 5 parts by mass, not only the curing is saturated but also the workability is deteriorated.

  In the present invention, it is further preferable that the thermosetting resin composition contains a curing catalyst for a blocked isocyanate resin. As a curing catalyst for the blocked isocyanate resin, di-n-butyltin oxide, n-dibutyltin chloride, di-n-butyltin dilaurate, di-n-butyltin diacetate, di-n-octyltin oxide, di- Examples include n-octyltin dilaurate and tetra-n-butyltin.

  The thermosetting resin composition of the present invention can selectively contain 0.5 to 8 parts by mass of acrylic resin beads in a solid content per 100 parts by mass of the thermosetting resin composition. Clear coated stainless steel sheet with excellent invaral design by including acrylic resin beads in clear paint containing blocked isocyanate resin and amino resin as resin for cross-linking and curing acrylic resin of thermosetting resin composition Can be obtained.

  The acrylic resin beads are true spherical crosslinked polymer fine particles whose average particle diameter can be controlled between several μm to several hundred μm. By containing it, the imparting of design properties, the effect of matting, the imparting of fingerprint resistance due to the roughness of the surface state, and the resistance to wrinkles are improved. As acrylic resin beads, Art Pearl G-200 transparent, G-400 transparent, G-800 transparent (above, manufactured by Negami Industrial Co., Ltd.), Techpolymer MBX-12, MBX-15, MBX-20, MBX-30, ARX-15, ARX-30 (above, manufactured by Sekisui Plastics Co., Ltd.), Toughtick AR650S, AR650M (above, manufactured by Toyobo Co., Ltd.), Rabkorol 220, 030, 230, 330, 530, transparent types (above) , Dainichi Seika Kogyo Co., Ltd.), Gantz Pearl GM0605, GM1005, GM2005 (Gantz Kasei Co., Ltd.) and the like, and may be selected as a single product or in combination depending on the compatibility with the acrylic resin. The content of 0.5 to 8 parts by mass is preferable per 100 parts by mass of the thermosetting resin composition, but 2 to 4 parts by mass is more preferable. If the amount is less than 0.5 parts by mass, the designability cannot be imparted and the invaral tone is not obtained. In addition, the antifouling resistance to fingerprints decreases, and fingerprints are easily attached when directly touching the coating film, and wiping with gauze is not easy. If it exceeds 8 parts by mass, the effect of antifouling resistance to fingerprints is maintained, but the gloss of the coating film becomes too low, and the high-quality feeling of the clear coated stainless steel sheet is lost. The average particle diameter of the acrylic resin beads is preferably 6 to 30 μm, more preferably 6 to 15 μm. When the average particle size is other than 6 to 30 μm, the designability cannot be imparted and the invaral tone is not obtained. In addition, the colored resin beads give a color to the coating film, and the stainless steel feeling is lost, so that it does not become an invaral design. When urethane resin beads are used, the same tactile sensation can be obtained, but the storage stability of the paint is poor, the design is changed and the invaral tone is not obtained.

  Examples of the present invention and comparative examples will be described below. In the examples, the term “parts” simply indicates mass parts, and the term “%” indicates mass%.

  A 4-necked flask equipped with a thermometer, reflux condenser, stirrer, dropping funnel, and nitrogen gas inlet tube is charged with a specified amount of toluene and butyl acetate as shown in Table 1. The temperature is raised to 110 ° C and stirring is performed while blowing nitrogen gas. And a mixture of methyl methacrylate, styrene, n-butyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, methyl acrylate, azobisisobutyronitrile (AIBN) over 3 hours. After the dropwise addition, AIBN was further added after completion of the dropwise addition, and the mixture was further reacted at the same temperature for 3 hours to obtain an acrylic copolymer having a nonvolatile content of 50%. Furthermore, blocked isocyanate “Desmodur VPLS 2253” (manufactured by Sumika Bayer Urethane Co., Ltd.), which is a curing agent, was blended as shown in Table 1 to obtain a clear paint.

  In the manufacture of the top coating, a clear coating was obtained according to the blending ratio shown in Table 1.

  As a comparative clear paint, a polymer polyester / melamine resin paint “Coil Coat 475 Clear” (Kawakami Paint) was used.

  As the metal plate, stainless steel plate SUS430 / No. 4 Abrasive finish was used.

On these stainless steel plates, the chemical conversion coating film treatment liquid of the present invention was applied by a fluorescent coater with a roll coater so that the SiO ₂ was ₂ to 50 mg / m ² , and the plate temperature (MT) was 100 ° C It was made to dry. Subsequently, the clear paint of the present invention was baked with a bar coater so that the plate temperature (MT) was 193 ° C. 1 to 25 clear-coated stainless steel sheets were obtained. The traveling speed of the coating line was 50 m / min. Hereinafter, the same traveling speed was used except for Example 3.

  For comparison, a coated stainless steel plate in which clear coating is outside the scope of the present invention, a coated stainless steel plate in which the chemical conversion coating is a coating-type chromate treatment, and a coated stainless steel plate without a chemical conversion coating are the same as in the above invention examples. In Comparative Example No. 26-37 stainless steel sheets were obtained.

  For these test materials, the clearability, hardness, rain-stain stain resistance, detergent resistance, chemical resistance, weather resistance test, moldability (Ericsen test), and salt spray resistance of the coating film were examined. The results are shown in Tables 2 and 3.

The evaluation method of the coating film is as follows.
(1) Clearness of the coating film The color state of the coating film was measured with a color difference meter CR-300 (manufactured by Minolta Co., Ltd.) by the color difference Δb value between the material baked at a plate temperature of 193 ° C. and the material coated with clear coating. (Δb large → yellow large)

(2) Hardness It evaluated according to JIS K5600 5-4 scratch hardness (pencil method). (4 or more was accepted)
5: 6H or more (pass)
4: 5H (pass)
3: 4H (failed)
2: 3H (failed)
1: 2H or less (failed)

(3) Rain streak contamination The specimens were subjected to a natural exposure test for 3 months, and the condition of the rain streaks of the paint film was evaluated.
5: No trace at all (passed)
4: Traces are slightly recognized (pass)
3: Traces are slightly noticeable (failed)
2: Mark remains dark (failed)
1: Peel off (failed)

(4) Detergent resistance The specimen was attached to magic phosphorus for 72 hours at 40 ° C., and the state of the coating film was observed and evaluated.
5: No trace at all (passed)
4: Traces are slightly recognized (pass)
3: Traces are slightly noticeable (failed)
2: Mark remains dark (failed)
1: Peel off (failed)

(5) Chemical resistance 2 mL of 5% sulfuric acid and 5% NaOH were dropped on the test material, and after capping, the state of the coating film after 16 hours was observed and evaluated.
5: No trace at all (passed)
4: Traces are slightly recognized (pass)
3: Traces are slightly noticeable (failed)
2: Mark remains dark (failed)
1: Peel off (failed)

(6) Weather resistance It evaluated by the gloss retention (%) after 1000 hours of the SWOM test.
5: Gloss retention 80-100% (pass)
4: Gloss retention 60-80% (pass)
3: Gloss retention 40-60% (failed)
2: Gloss retention 20-40% (failed)
1: Gloss retention 0-20% (failed)

(7) Eriksen value It evaluated according to JISZ2247. (When SUS430 graphite grease was used, it was 9.3 mm, so more than that was accepted.)

(8) Salt water spray test A cross-cut was applied to the coating film, a salt spray test was conducted for 500 hours in accordance with the method of JIS Z2371, and the peeling state of the coating film was visually evaluated.
5: Peeling rate less than 5% (pass)
4: Stripping rate of 5% or more and less than 10% (pass)
3: Peeling rate of 10% or more and less than 15% (failed)
2: Stripping rate of 15% or more and less than 20% (failed)
1: Peeling rate of 20% or more (failed)

  According to the present invention, it is possible to obtain a clear-coated stainless steel sheet that does not emit hexavalent chromium, and that is compatible with an environment having excellent clearability, hardness, rain-stain contamination, detergent resistance, chemical resistance, and weather resistance. it can. Furthermore, by containing 0.25 to 5 parts by mass of a polyolefin wax in solid content per 100 parts by mass of a solid material of a thermosetting resin, lubrication having better formability than a stainless steel plate coated with an oil-based lubricant or the like. A clear-coated stainless steel sheet having excellent properties can be obtained.

  On the other hand, in the comparative example, the adhesiveness is poor without chemical conversion treatment, and the chromate treatment material has a yellowish surface and contains hexavalent chromium. Furthermore, the conventional polyester / melamine resin coating may be inferior in hardness, rain-stain stain resistance, detergent resistance, chemical resistance, and weather resistance. Further, those having an average molecular weight or glass transition point outside the scope of the invention have defects such as inferior hardness and manufacturability.

A stainless steel plate (SUS430 / No. 4 polishing finish) was coated with the chemical conversion coating solution of the present invention using a roll coater so that the SiO ₂ was ₂ to 50 mg / m ² with fluorescent X-rays, and the plate temperature ( (MT) was dried to 100 ° C. Subsequently, the clear paint of the present invention (Table 1) was baked with a bar coater so that the plate temperature (MT) was 193 ° C. 1 to 12 clear-coated stainless steel sheets were obtained. The chain water-dispersible silica was contained in the chemical conversion coating film.

  For comparison, the conversion-treated coating film does not contain chain water-dispersible silica (Comparative Example 1), and the chemical-treatment coating film contains 50% chain solid water-dispersible silica (solid content ratio) (Comparative Example) 2) A chemical conversion coating film in which ordinary spherical water-dispersed silica “Snowtex C” (Nissan Chemical Co., Ltd.) is put in place of the chain water-dispersible silica (Comparative Example 3), Chromate type "Allodin 1000 (Nippon Parkerizing Co., Ltd.)" (Comparative Example 4), clear paint of polyester type (Comparative Example 5), clear paint of B-1 and B-2 in Table 1 ( Comparative Examples 6 and 7), the chemical conversion coating films having an adhesion amount of 1 mg and 100 mg (Comparative Examples 8 and 9) were treated in the same manner as in the above-mentioned invention examples, and Comparative Examples No. 1 to 9 stainless steel sheets were obtained.

  For these test materials, the gloss, clearness, hardness, rain-stain contamination, detergent resistance, chemical resistance, weather resistance test, and cupping resistance of the coating film were examined. The results are shown in Table 4.

The evaluation method of the coating film is as follows.
(1) Gloss Measured according to JIS K5600 4-7 (mirror glossiness), and 110 or more was regarded as acceptable.
5: 130 or more (pass)
4: 110-130 (pass)
3: 90-110 (failed)
2: 70-90 (failed)
1:70 or less (failed)

(2) Adhesiveness It was immersed in boiling water for 1 hour, and the adhesiveness after standing for 30 minutes was evaluated by a cross cut test. In accordance with JIS K5600 5-6, the evaluation was 8 points or more.
5: (Pass): 10 points
4: (Pass): 8-9 points
3: (failed): 7-6 points
2: (Fail): 5-4 points
1: (Fail): 3 points or less

(3) Cupping resistance It evaluated according to JIS K5600 5-2.
5: 9 mm or more (pass)
4: 7-9mm (pass)
3: 5-7 mm (failed)
2: 3-5 mm (failed)
1: 3 mm or less (failed)

(4) The evaluation method of the clearness, hardness, rain-stain contamination, detergent resistance, chemical resistance, and weather resistance of the coating film was the same as in Example 1.

  According to the present invention, a surface treatment is performed with a treatment liquid in which a chain-like water-dispersible silica is mixed with a non-chromate metal surface treatment agent, and after applying a chemical conversion coating film, a clear coating is applied. A clear coated stainless steel sheet having gloss can be obtained.

  On the other hand, in the comparative example, the one in which no chain water-dispersible silica is added to the chemical conversion coating film (Comparative Example 1) is inferior in gloss, and one in which 50% (solid content ratio) of chain water-dispersible silica is added In Example 2), the gloss is good, but the stability, adhesion, and coupling resistance of the metal treatment solution are poor, and a normal spherical water-dispersed silica is added to the chemical conversion coating film instead of the chain water-dispersible silica. (Comparative example 3) is inferior in gloss, and the chemical conversion coating film having a chromate coating (Comparative Example 4) contains hexavalent chromium and is not environmentally friendly. The clear paint (polyester 5) and the clear paint B-1 and B-2 (comparative examples 6 and 7) in Table 1 are inferior in adhesion and hardness. Those having an adhesion amount of the chemical conversion coating film of 1 mg and 100 mg (Comparative Examples 8 and 9) are inferior in adhesion.

  The acrylic copolymer obtained by the method of Example 1 was further blended with block isocyanate “Desmodur VPLS 2253” (manufactured by Sumika Bayer Urethane Co., Ltd.), which is a curing agent, and a melamine resin as an amino resin as shown in Table 5. A clear paint was obtained. Organosilica sol, amorphous silica and polyolefin wax were included in the clear coating of Table 5.

A stainless steel plate (SUS430 / No. 4 polishing finish) was coated with the chemical conversion coating solution of the present invention using a roll coater so that the SiO ₂ was ₂ to 50 mg / m ² with fluorescent X-rays, and the plate temperature ( (MT) was dried to 100 ° C. The clear paint of the present invention (Table 5) was baked with a bar coater so that the plate temperature (MT) was 193 ° C. 1-14 clear coated stainless steel sheets were obtained. In this example, since the clear coating film contains an amino resin, the curing speed becomes slow, so the steel plate traveling speed of the coating line was set to 35 m / min.

  For comparison, a clear-coated stainless steel plate whose clear coating is out of the scope of the present invention was treated in the same manner as in the above-mentioned inventive examples. 1-14 stainless steel sheets were obtained.

  For these test materials, the processability, hardness, glossiness, scratch resistance, fingerprint stain resistance, detergent resistance, and chemical resistance tests of the coating film were examined. The results are shown in Tables 6 and 7.

The evaluation method of the coating film is as follows.
(1) Workability of coating film It evaluated according to JIS K5600 5-2 (cupping resistance).
5: 7 mm or more (pass)
4: 5-7mm (pass)
3: 3-5 mm (failed)
2: 1-3 mm (failed)
1: 1mm or less (failed)

(2) Hardness It evaluated according to JIS K5600 5-4 scratch hardness (pencil method).
5: 6H or more (pass)
4: 5H (pass)
3: 4H (failed)
2: 3H (failed)
1: 2H or less (failed)

(3) Glossiness JIS K5600 4-7 Evaluation was made according to the specular glossiness.
5: 90 or more (pass)
4: 70-90 (pass)
3: 50-70 (failed)
2: 30-50 (failed)
1:30 or less (failed)

(4) Scratch resistance A household detergent “Gif” (manufactured by Japan Lever) containing abrasives is dropped on 4 sheets of gauze and rubbed 100 times with a 1 kg load to evaluate the tackiness.
5: No wrinkle (pass)
4: Flaws are hardly noticeable (pass)
3: A wrinkle can be clearly confirmed (failed)
2: Gloss of the paint film is lost with blemish (failed)
1: The coating film is scraped and reaches the substrate (failed)

(5) Anti-fingerprint contamination Hold the coated surface with a finger with a force of 1 kg, check how the fingerprint is attached, and wipe off the attached fingerprint with gauze.
5: No fingerprint (pass)
4: Fingerprints are hardly noticeable (pass)
3: The fingerprint can be confirmed slightly and is easy to remove (failed)
2: The fingerprint is slightly visible and difficult to remove (failed)
1: The fingerprint can be clearly confirmed (failed)

(6) The detergent resistance and chemical resistance were evaluated in the same manner as in Example 1.

  According to the present invention examples 1 and 2 in Table 6, it was excellent in scratch resistance by applying a clear paint containing an amino resin (melamine resin) as a resin for crosslinking and curing the thermosetting resin composition. A clear-coated stainless steel sheet can be obtained. Moreover, this invention 3-18 of Table 6 can obtain the clear coating stainless steel plate which was further excellent by the scratch resistance by apply | coating the clear coating material containing organosilica sol in a thermosetting resin composition. Furthermore, the present inventions 5 to 18 in Table 6 are clear coatings having excellent anti-fingerprint resistance in addition to scratch resistance by applying a clear coating containing amorphous silica in a thermosetting resin composition. A coated stainless steel sheet can be obtained. Since Inventions 1 to 18 contain polyolefin wax within the scope of the present invention, the processability or glossiness of the coating film is excellent, and the scratch resistance and fingerprint stain resistance are also excellent.

  On the other hand, Comparative Example 1 in Table 7 does not contain an amino resin, so that the scratch resistance is not sufficiently improved. When the organosilica sol content exceeds the range of the present invention (Comparative Example 2), the processability and chemical resistance of the coating film are poor. When the amorphous silica content exceeds the range of the present invention (Comparative Example 9), the gloss is inferior. When the clear paint is out of the scope of the present invention (Comparative Examples 10 and 11), the scratch resistance and the processability of the coating film are inferior. Even if the clear paint containing the amino resin (melamine resin), the oregano silica gel and the amorphous silica are within the scope of the present invention, the polyolefin wax is outside the scope of the present invention (Comparative Examples 5 to 8). The processability or glossiness of the film is inferior, and the scratch resistance and fingerprint contamination resistance are also deteriorated. In addition, those having a polyolefin wax content less than the range of the present invention (Comparative Examples 3 and 4) do not have improved lubricity as compared with those containing a polyolefin wax within the range of the present invention.

  In addition, about the comparative example 1 which apply | coated the clear coating material which does not contain an amino resin, although the abrasion-resistant evaluation result in a present Example is the parameter | index 3 or less, the favorable result of 4 or more is shown about hardness. . Therefore, it can be used as a sufficiently good clear-coated stainless steel sheet for applications that do not require such severe scratch resistance.

  The acrylic copolymer obtained by the method of Example 1 was further mixed with block isocyanate “Desmodur VPLS 2253” (manufactured by Sumika Bayer Urethane Co., Ltd.), which is a curing agent, and melamine resin (Cymel 327) as an amino resin in Table 8. Thus, a clear paint was obtained. The organosilica sol, amorphous silica, polyolefin wax and curing catalyst were contained in the clear coating of Table 8.

A stainless steel plate (SUS430 / No. 4 polishing finish) was coated with the chemical conversion coating solution of the present invention using a roll coater so that the SiO ₂ was ₂ to 50 mg / m ² with fluorescent X-rays, and the plate temperature ( (MT) was dried to 100 ° C. The clear paint of the present invention (Table 8) was baked with a bar coater so that the plate temperature (MT) was 193 ° C. 1-19 clear coated stainless steel sheets were obtained. Since the curing speed is increased by containing the curing catalyst, the steel plate traveling speed of the coating line is set to 50 m / min in principle.

  For comparison, a clear-coated stainless steel plate whose clear coating is out of the scope of the present invention was treated in the same manner as in the above-mentioned inventive examples. 1-14 stainless steel sheets were obtained.

  For these test materials, the processability, hardness, glossiness, scratch resistance, fingerprint stain resistance, detergent resistance, and chemical resistance tests of the coating film were examined. The results are shown in Tables 9 and 10.

  The method for evaluating the coating film is the same as in Example 3.

  According to the present invention shown in Table 9, in a clear paint containing a blocked isocyanate resin and an amino resin as a resin for cross-linking and curing the thermosetting resin composition, a curing catalyst for accelerating the cross-linking and hardening of the clear coating film By applying a clear paint containing di-n-butyltin dilaurate to the blocked isocyanate resin and P-toluenesulfonic acid to the amino resin, the steel plate running speed is sufficient even at 50 m / min. Good scratch resistance was secured. That is, a scratch-resistant clear-coated stainless steel sheet having excellent productivity can be obtained. Furthermore, the present inventions 3 to 19 in Table 9 can further improve the scratch resistance by containing an organosilica sol. Further, the present inventions 1 and 3 to 19 in Table 9 can be a clear-coated stainless steel plate having excellent antifingerprint resistance by containing amorphous silica in the clear paint.

  On the other hand, in the comparative examples shown in Table 10, those which do not contain P-toluenesulfonic acid as a curing catalyst for amino resins or are outside the lower limit of the scope of the present invention (Comparative Examples 8 and 9) are inferior in scratch resistance. What exceeds the range (Comparative Example 10) is inferior in workability of the coating film. An amino resin curing catalyst containing dodecylbenzenesulfonic acid instead of P-toluenesulfonic acid (Comparative Example 11) is inferior in hardness and scratch resistance. That is, when it does not contain a curing catalyst, it means that the crosslinking rate is slow and the productivity is inhibited. Practically, in the present invention, it is possible to impart high functionality such as scratch resistance while increasing the line speed, but this is not possible in the comparative example. When the organosilica sol content exceeds the range of the present invention (Comparative Example 1), the processability and chemical resistance of the coating film are poor. When the clear paint is out of the scope of the present invention (Comparative Examples 12 and 13), the scratch resistance and the processability of the coating film are inferior. Even if the clear paint, the oregano silica sol and the amorphous silica are within the scope of the present invention, those in which the polyolefin wax is outside the scope of the present invention (Comparative Examples 2 to 7) have poor processability or glossiness of the coating film. Scratch resistance and fingerprint contamination resistance also deteriorate. Since Comparative Example 14 does not contain an amino resin in the thermosetting resin composition, the scratch resistance and hardness are not improved.

  Example 4 A block isocyanate “Desmodur VPLS 2253” (manufactured by Sumika Bayer Urethane Co., Ltd.) as a curing agent and a melamine resin (Cymel 327) as an amino resin were added to the acrylic copolymer obtained by the method of Example 1. Were mixed as shown in Table 8 to obtain a clear paint. Polyolefin wax and resin beads were included in the clear paint of Table 8.

A stainless steel plate (SUS430 / No. 4 polishing finish) was coated with the chemical conversion coating solution of the present invention using a roll coater so that the SiO ₂ was ₂ to 50 mg / m ² with fluorescent X-rays, and the plate temperature ( (MT) was dried to 100 ° C. The clear paint of the present invention (Table 8) was baked with a bar coater so that the plate temperature (MT) was 193 ° C. 1-17 clear-coated stainless steel sheets were obtained.

  For comparison, a clear-coated stainless steel plate whose clear coating is out of the scope of the present invention was treated in the same manner as in the above-mentioned inventive examples. 1 to 16 stainless steel plates were obtained.

  For these test materials, the processability, hardness, glossiness, scratch resistance, fingerprint stain resistance, detergent resistance, and chemical resistance tests of the coating film were examined. The results are shown in Tables 11 and 12.

The evaluation method of the coating film is as follows.
(1) Designability / appearance Compare design characteristics with invaral material (stainless steel).
5: No difference at all (pass)
4: Almost no difference (pass)
3: The difference is slightly noticeable (failed)
2: The difference is noticeable (failed)
1: Clearly understand the difference (failed)

(2) Storage stability The state of the paint after 144 hours at 43 ° C. was observed and evaluated.
5: No abnormality at all (pass)
4: Slightly abnormal paint condition (pass)
3: Slight increase in viscosity is observed (failed)
2: Slightly thickening tendency is observed (failed)
1: Completely gelled and thickened (failed)

(3) The processability, hardness, wrinkle resistance, fingerprint stain resistance, detergent resistance, and chemical resistance of the coating film were evaluated by the method of Example 4. The results are shown in Tables 11 and 12.

  According to the present invention, a clear paint containing a blocked isocyanate resin and an amino resin as a resin for cross-linking and curing a thermosetting resin composition of an acrylic resin, and an acrylic resin bead is added to an invaral design. An excellent clear-coated stainless steel sheet can be obtained.

  On the other hand, in a comparative example, what does not contain acrylic resin beads (Comparative Example 1) is inferior in design. Those in which the acrylic resin beads are out of the scope of the present invention (Comparative Examples 2 to 4) are inferior in design and gloss. Those containing urethane resin beads instead of acrylic resin beads (Comparative Examples 5 to 7) are inferior in storage stability. When the clear paint is out of the scope of the present invention (Comparative Examples 8 and 9), the design and gloss are inferior. When the polyolefin wax is outside the scope of the present invention (Comparative Examples 10 and 11), the designability and the processability of the coating film are inferior when the lower limit is exceeded, and the designability and hardness are inferior when the upper limit is exceeded.

Claims (18)

In clear-coated stainless steel plate, the upper layer is formed of a clear coating film and the lower layer is formed of a chemical conversion coating film, the chemical conversion coating film is substantially composed of one or two types of aminosilane type and epoxysilane type, and the chemical conversion coating film is attached. The acrylic resin having an amount of ² to 50 mg / m ² and a clear coating film having a crosslinkable functional group having a glass transition point of 30 to 90 ° C. and a number average molecular weight of 3000 to 50000 is crosslinked and cured. A clear-coated stainless steel sheet, characterized in that it is a thermosetting resin composition containing a blocked isocyanate compound and has a clear coating film thickness of 1 to 10 μm.   2. The clear coated stainless steel according to claim 1, wherein the clear coating film contains 0.25 to 5 parts by mass of a polyolefin wax in a solid content per 100 parts by mass of the solid of the thermosetting resin composition. steel sheet.   The clear-coated stainless steel sheet according to claim 1 or 2, wherein the chemical conversion coating film contains 0.1 to 30% (solid content ratio) of chain-like water-dispersible silica and has high gloss.   The clear-coated stainless steel sheet according to any one of claims 2 to 3, wherein the thermosetting resin composition contains an amino resin as a resin for crosslinking and curing the acrylic resin, and has excellent scratch resistance. .   The clear according to claim 4, wherein the thermosetting resin composition is a composition containing 2 to 10 parts by mass of an organosilica sol per 100 parts by mass of the solid. Painted stainless steel sheet.   The thermosetting resin composition contains 0.5 to 5 parts by mass of amorphous silica per 100 parts by mass of the solid material, and is excellent in fingerprint stain resistance and wrinkle resistance. The clear coated stainless steel sheet according to any one of?   The thermosetting resin composition contains 0.5 to 5 parts by mass of a P-toluenesulfonic acid catalyst as a curing catalyst for the amino resin per 100 parts by mass of the solid material of the thermosetting resin composition. The clear coated stainless steel sheet according to any one of claims 4 to 6, which is excellent in productivity, fingerprint resistance and wrinkle resistance.   The clear-coated stainless steel sheet according to claim 7, wherein the thermosetting resin composition contains a curing catalyst for the blocked isocyanate resin and is excellent in productivity, fingerprint resistance and wrinkle resistance.   The clear coating according to claim 4, wherein the thermosetting resin composition has 0.5 to 8 parts by mass of acrylic resin beads per 100 parts by mass of the solid. Stainless steel sheet. A method for producing a stainless steel sheet in which the upper layer is formed of a clear coating film and the lower layer is formed of a chemical conversion coating film, and the amount of adhesion is 2 to 50 mg of a chemical conversion coating film composed of one or two types of aminosilane type and epoxysilane type. / m ² and so as to be applied, it is then a glass transition point having a crosslinkable functional group as a clear coating film is 30 to 90 ° C., crosslinking and curing the acrylic resin acrylic resin having a number average molecular weight of 3,000 to 50,000 as a main component A method for producing a clear-coated stainless steel sheet, which comprises applying a thermosetting resin composition containing a blocked isocyanate compound for the coating to a clear coating film thickness of 1 to 10 μm.   The said thermosetting resin composition contains 0.25-5 mass parts of polyolefin wax by solid content per 100 mass parts of solids, The manufacture of the clear coated stainless steel plate of Claim 10 characterized by the above-mentioned. Method.   The said chemical conversion coating film contains 0.1-30% (solid content ratio) of chain | strand-shaped water-dispersible silica, The manufacture of the clear coated stainless steel plate of Claim 10 or 11 characterized by the above-mentioned. Method.   The clear coated stainless steel sheet according to any one of claims 11 to 12, wherein the thermosetting resin composition contains an amino resin as a resin for crosslinking and curing the acrylic resin, and has excellent scratch resistance. Manufacturing method.   The clear according to claim 13, wherein the thermosetting resin composition is a composition containing 2 to 10 parts by mass of an organosilica sol per 100 parts by mass of the solid. Manufacturing method of painted stainless steel sheet.   The thermosetting resin composition contains 0.5 to 5 parts by mass of amorphous silica per 100 parts by mass of the solid material, and is excellent in fingerprint stain resistance and wrinkle resistance. The manufacturing method of the clear coating stainless steel plate of -14.   The thermosetting resin composition contains 0.5 to 5 parts by mass of a P-toluenesulfonic acid catalyst as a curing catalyst for the amino resin per 100 parts by mass of the solid material of the thermosetting resin composition. The method for producing a clear coated stainless steel sheet according to any one of claims 13 to 15, which is excellent in productivity, fingerprint resistance and wrinkle resistance.   The said thermosetting resin composition contains the curing catalyst of the said block isocyanate resin, The manufacture of the clear coated stainless steel plate of Claim 16 excellent in productivity, fingerprint resistance, and wrinkle resistance characterized by the above-mentioned. Method.   14. The clear coating according to claim 13, wherein the thermosetting resin composition contains 0.5 to 8 parts by mass of acrylic resin beads per 100 parts by mass of the solid. Manufacturing method of stainless steel sheet.