JP2009061608A - Resin-coated metallic plate having excellent roll formability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin-coated metallic plate which does not cause troubles in a roll forming while having characteristics such as corrosion resistance required for the resin-coated metallic plate. <P>SOLUTION: The resin-coated metallic plate includes a resin film that is obtained from a surface treatment composition. In the resin-coated metallic plate having excellent roll formability, the surface treatment composition comprises, by pass: 60-95 parts of a non-organic component composed of lithium silicate and colloidal silica; and 5-40 parts of a resin component which contains 1-9 parts of oxazoline group containing copolymer based on total 100 parts of olefine-α,β-unsaturated carboxylic acid copolymer and α,β-unsaturated carboxylic acid polymer. In addition, the surface treatment composition further comprises: 7-35 parts of a glycidyl group containing silane coupling agent and 0.5-7 parts of methavanadate based on total 100 parts of the non-organic component and the resin component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin-coated metal plate used for automobiles, home appliances, building materials, and the like, and particularly relates to a resin-coated metal plate particularly excellent in corrosion resistance and roll formability.

  From the viewpoint of corrosion resistance, zinc-based plated steel sheets such as electrogalvanized steel sheets and hot-dip galvanized steel sheets are used for building materials. Conventionally, chromate treatment has been applied to zinc-based plated steel sheets for the purpose of further improving corrosion resistance. However, due to the recent increase in environmental awareness, demand for steel sheets not subjected to chromate treatment is increasing.

  For example, Patent Document 1 proposes a metal surface treatment agent containing a copolymer emulsion of an α, β-ethylenically unsaturated carboxylic acid and an olefin and a cross-linking agent as means for improving corrosion resistance in place of such chromate treatment. ing. Patent Document 2 proposes a surface treatment agent containing a carboxyl group-containing resin and an inorganic silicate, and a surface-treated steel sheet obtained therefrom. Recently, however, even higher levels of corrosion resistance have been demanded for resin-coated steel sheets not subjected to chromate treatment. In the field of resin-coated metal sheets, means for improving corrosion resistance are constantly being sought. Yes.

  By the way, the resin-coated metal plate is processed and molded according to the application. For example, the roll forming method suitable for the production of long cross-section materials is to pass a metal plate continuously between a plurality of sets of rolls arranged in a row, and sequentially perform the forming process, from the flat plate to the desired cross-sectional shape It is a method of processing into a molded product. In roll forming, a coolant is supplied to the surface of the metal plate in order to ensure lubricity and to cool the processing heat. This coolant liquid is removed by wiping the surface of the metal plate with a draining pad before the step of cutting the molded product (draining step).

When performing severe processing with high surface pressure such as the above roll forming (molding speed of about 20 to 80 m / min), if the processability of the resin film of the resin-coated metal plate is inferior, the resin film is removed from the surface of the metal plate. It may peel off slightly (film residue). Although this film residue is introduced into the coolant tank, the resin film has a specific gravity as low as about 1 and therefore floats in the liquid without sinking to the bottom of the coolant tank. The coolant circulation system is usually equipped with a filter, but the filter is designed to catch galvanized strips, so the filter is fine enough to catch the resin film residue. In other words, the film residue accompanies the coolant liquid that is repeatedly used. As a result, film residue gradually accumulates on the surface of the draining pad in the draining process, and friction is generated between the deposited film residue and the surface of the molded product, or abnormal noise is generated, or the molded product uniformly distributes the drained pad portion. There is a problem in that it is impossible to pass through at the traveling speed, the shape and dimensions of the product are distorted, and the yield is deteriorated.
JP 2005-220237 A JP 2000-282254 A

  Therefore, the present invention has been made to provide a resin-coated metal plate that has the characteristics required for a resin-coated metal plate such as corrosion resistance, and that does not cause troubles in roll forming as described above.

  The resin-coated metal plate excellent in roll formability of the present invention that has solved the above problems is a resin-coated metal plate provided with a resin film obtained from the surface treatment composition, wherein the surface treatment composition comprises lithium silicate and 60 to 95 parts by mass of the inorganic component made of colloidal silica and 100 parts by mass of the total of the olefin-α, β-unsaturated carboxylic acid copolymer and α, β-unsaturated carboxylic acid polymer, While containing 5 to 40 parts by mass of the resin component containing 1 to 9 parts by mass of the polymer, further 7 to 35 parts by mass of the glycidyl group-containing silane coupling agent with respect to 100 parts by mass in total of the inorganic component and the resin component. And 0.5-7 parts by mass of metavanadate.

The lithium silicate and colloidal silica in the surface treatment composition are 95: 5 to 80:20 in mass ratio, the surface area average particle diameter of the colloidal silica is 4 to 20 nm, When the total of the olefin-α, β-unsaturated carboxylic acid copolymer and the α, β-unsaturated carboxylic acid polymer is 100 parts by mass, the carbodiimide group-containing compound is further added in an amount of 0. It is a suitable embodiment of this invention that it contains in the ratio of 1-30 mass parts, and the adhesion amount of a resin film is 0.1-1 g / m < ² > by dry mass.

  In the present invention, since the resin film is obtained from a surface treatment composition in which specific components are combined in an optimum amount, the resulting resin film has excellent properties such as corrosion resistance and good roll forming with less generation of film residue. Also expresses sex. In addition, the amount of inorganic components in the resin film is large, and the specific gravity of the film has increased by about 2 to 3 times compared to the conventional organic resin-rich film. Sedimentation began to settle at the bottom. As a result, film accumulation on the surface of the draining pad hardly occurred, and roll forming can be performed at a high yield for a long period of time.

  The present inventors have found a surface treatment composition capable of forming a resin film having excellent corrosion resistance and have already filed an application (Japanese Patent Application No. 2007-56966). As a result of intensive studies aimed at improving roll formability while maintaining the excellent corrosion resistance and top coat adhesion (paintability) of this surface treatment composition, the present inventors have reached the present invention. It is. This will be described in detail below. In addition, although the film of the present invention contains an inorganic component considerably more than the resin component, it also includes a resin component, and in this field, it is often referred to as “resin film”. The term “film” was used.

  The present invention relates to a resin-coated metal plate provided with a resin film obtained from a surface treatment composition, and the characteristics thereof are in each component of the surface treatment composition.

Inorganic Component The surface treatment composition of the present invention includes an inorganic component composed of lithium silicate and colloidal silica. Lithium silicate is excellent in film forming property and has an action of forming a film excellent in corrosion resistance, workability and paintability. In addition, the specific gravity of the film is increased to promote sedimentation of the film residue. As lithium silicate (lithium silicate), for example, from Nissan Chemical Industries, lithium silicate 35 (SiO ₂ / Li ₂ O is 3.5 in molar ratio), lithium silicate 45 (SiO ₂ / Li ₂ O is molar ratio) 4.5) and lithium silicate 75 (SiO ₂ / Li ₂ O is 7.5 in molar ratio) is commercially available. When the molar ratio of SiO ₂ / Li ₂ O is in the range of 3.5 to 7.5, it is preferable because both water resistance and film forming property can be achieved.

  Colloidal silica dissolves and elutes at a film defect in a corrosive environment and suppresses dissolution / elution of the metal plate by a pH buffering action or a passive film forming action, thereby improving the corrosion resistance. In order to sufficiently exhibit these effects, the surface area (particle diameter) of colloidal silica is preferably 4 to 20 nm in terms of surface area average particle diameter. If it is larger than 20 nm, the surface area itself becomes small and the effect of improving corrosion resistance may be reduced. In addition, the dispersibility, alkali resistance, and resin film adhesion may be reduced. On the other hand, if the thickness is less than 4 nm, the storage stability of the surface treatment composition may be deteriorated and gelation may occur. Even if the colloidal silica is too small, the effect of improving the corrosion resistance is saturated, and conversely, the activity of the silica becomes too high, and the surface treatment composition may gel and a good resin film may not be formed. As for the surface area average particle diameter of colloidal silica, 4-6 nm is more preferable. The surface area average particle diameter of silica can be measured by the Sears method when the average particle diameter is about 1 to 10 nm and by the BET method when it is about 10 to 100 nm.

  Colloidal silica is commercially available. For example, if it has a surface area average particle size of 4 to 6 nm, “Snowtex (registered trademark) XS” manufactured by Nissan Chemical Industries, Ltd. can be used. Also, "Snowtex (registered trademark) 40", "Snowtex (registered trademark) N", "Snowtex (registered trademark) SS", "Snowtex (registered trademark) O", etc., also manufactured by Nissan Chemical Industries, "Adelite (registered trademark) AT-30", "Adelite (registered trademark) AT-30A" manufactured by ADEKA, etc. can be used. When the surface treatment composition used for forming the resin film is aqueous, it is preferable to select the type of colloidal silica according to the pH of the surface treatment composition in order to disperse the colloidal silica well.

  The inorganic component consisting of lithium silicate and colloidal silica is 60 to 95 parts by mass in a total of 100 parts by mass with the resin component described later. When the amount of the inorganic component is less than 60 parts by mass, the hardness of the resin film is insufficient and it is difficult to reduce the thickness. In addition, since the specific gravity of the film does not increase so much, it becomes impossible to settle the film residue in the coolant bath, and the effect of suppressing the accumulation on the surface of the draining pad is insufficient, resulting in operability and product shape. It is not preferable because it deteriorates. However, when the amount of the inorganic component exceeds 95 parts by mass, the resin component is insufficient, the leveling property of the surface treatment composition is deteriorated, and troubles such as repelling occur during the application work to the metal plate are caused. A normal film cannot be formed. Further, the film becomes too hard and brittle, and the corrosion resistance and the like deteriorate. In a total of 100 parts by mass of the inorganic component and the resin component, the inorganic component is more preferably 80 to 95 parts by mass, and even more preferably 85 to 90 parts by mass.

  The ratio of lithium silicate to colloidal silica in the inorganic component is preferably 95: 5 to 80:20 (mass ratio). That is, it is preferable that lithium silicate is 80-95 mass% in 100 mass% of inorganic components. When lithium silicate is less than 80% by mass, the film forming action of lithium silicate becomes insufficient, and the amount of colloidal silica becomes excessive, so that the film hardness increases and a brittle film is formed. May increase. On the contrary, when lithium silicate exceeds 95 mass%, since the amount of colloidal silica is insufficient, corrosion resistance may be insufficient.

Resin Component The surface treatment composition used in the present invention may be abbreviated as olefin-α, β-unsaturated carboxylic acid copolymer (hereinafter referred to as “olefin-acid copolymer”) in addition to the inorganic component. ), An α, β-unsaturated carboxylic acid polymer (hereinafter sometimes abbreviated as “carboxylic acid polymer”), and an oxazoline group-containing copolymer capable of crosslinking with these. A resin component is included. The “α, β-unsaturated carboxylic acid” in the present invention also includes “α, β-unsaturated carboxylic acid salts” in which a part of the carboxyl group is neutralized with a neutralizing agent described later.

  The “olefin-α, β-unsaturated carboxylic acid copolymer” or “olefin-acid copolymer” in the present invention is a copolymer of an olefin and an α, β-unsaturated carboxylic acid, This means that the constituent unit derived from the copolymer is 50% by mass or more (that is, the constituent unit derived from α, β-unsaturated carboxylic acid is 50% by mass or less), “α, β-unsaturated carboxylic acid”. The “acid polymer” or “carboxylic acid polymer” is a polymer (including a copolymer) obtained using an α, β-unsaturated carboxylic acid as a monomer, and is an α, β-unsaturated carboxylic acid. It means that the derived structural unit is 90% by mass or more in the polymer.

  The exact mechanism by which the corrosion resistance of the resin-coated metal sheet is improved by surface treatment with a composition containing both an olefin-acid copolymer and a carboxylic acid polymer is unknown, but both of these are described below as oxazoline groups. By using together with the containing copolymer, it can be presumed that a dense resin film was formed and the permeation of water and oxygen was effectively suppressed. However, the present invention is not limited to this estimation.

  The olefin-acid copolymer used in the present invention can be produced by copolymerizing an olefin and an α, β-unsaturated carboxylic acid by a known method, and is commercially available. In the present invention, one or more olefin-acid copolymers can be used.

  Although there is no limitation in particular in the olefin which can be used for manufacture of an olefin-acid copolymer, ethylene, propylene, etc. are preferable and ethylene is more preferable. As the olefin-acid copolymer, any one in which the olefin structural unit is derived from only one olefin or from two or more olefins can be used.

  The α, β-unsaturated carboxylic acid that can be used for the production of the olefin-acid copolymer is not particularly limited, and examples thereof include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid, maleic acid, and fumaric acid. Examples thereof include dicarboxylic acids such as acid and itaconic acid. Among these, acrylic acid is preferable. As the olefin-acid copolymer, the constituent unit of α, β-unsaturated carboxylic acid is derived from only one kind of α, β-unsaturated carboxylic acid, or two or more kinds of α, β-unsaturated carboxylic acid. Any of those derived from acids can be used.

  The olefin-acid copolymer used in the present invention may have structural units derived from other monomers as long as they do not adversely affect the corrosion resistance and the like, which are the effects of the present invention. In the olefin-acid copolymer, the amount of structural units derived from other monomers is preferably 10% by mass or less, more preferably 5% by mass or less, and the most preferable olefin-acid copolymer is an olefin. It is composed only of-and α, β-unsaturated carboxylic acid. A preferred olefin-acid copolymer is an ethylene-acrylic acid copolymer.

  The α, β-unsaturated carboxylic acid in the olefin-acid copolymer is used to improve the adhesion between the resin film and the metal plate, and to secure the amount of carboxyl groups that are reactive groups for crosslinking. . The amount of α, β-unsaturated carboxylic acid in the copolymer is preferably 5% by mass or more, more preferably 10% by mass or more. However, if the α, β-unsaturated carboxylic acid is excessive, the corrosion resistance and alkali resistance may be lowered. Therefore, the amount is preferably 30% by mass or less, more preferably 25% by mass or less.

  The mass average molecular weight (Mw) of the olefin-acid copolymer used in the present invention is preferably 1,000 to 100,000, more preferably 3,000 to 70,000, and still more preferably 5,000 to 3, in terms of polystyrene. Ten thousand. This Mw can be measured by GPC using polystyrene as a standard.

  As the carboxylic acid polymer, either a homopolymer or copolymer of one or more α, β-unsaturated carboxylic acids, or a copolymer obtained by copolymerizing another monomer is used. can do. Such carboxylic acid polymers can be produced by known methods and are commercially available. In the present invention, one or more carboxylic acid polymers can be used.

  Examples of the α, β-unsaturated carboxylic acid that can be used for the production of the carboxylic acid polymer include the α, β-unsaturated carboxylic acids exemplified as those that can be used for the synthesis of the olefin-acid copolymer. It can be used. Among these, acrylic acid and maleic acid are preferable, and maleic acid is more preferable.

  The carboxylic acid polymer may contain a constitutional unit derived from a monomer other than the α, β-unsaturated carboxylic acid, but the amount of the constitutional unit derived from the other monomer is contained in the polymer. A carboxylic acid polymer composed of only an α, β-unsaturated carboxylic acid is more preferably 10% by mass or less, preferably 5% by mass or less.

  Preferred carboxylic acid polymers include, for example, polyacrylic acid, polymethacrylic acid, acrylic acid-maleic acid copolymer, polymaleic acid and the like. Among these, coating film adhesion, resin film adhesion, and corrosion resistance viewpoints Therefore, polymaleic acid is more preferable. Although the exact mechanism by which the corrosion resistance is improved by using polymaleic acid is unknown, the adhesion between the resin film and the metal plate is improved due to the large amount of carboxyl groups. It is done. However, the present invention is not limited to this estimation.

  Mw of the carboxylic acid polymer used in the present invention is preferably 500 to 30,000, more preferably 800 to 10,000, still more preferably 900 to 3,000, and most preferably 1,000 to 2,000 in terms of polystyrene. It is. This Mw can be measured by GPC using polystyrene as a standard.

  The content ratio of the olefin-acid copolymer and the carboxylic acid polymer in the surface treatment composition is 1,000: 1 to 10: 1, preferably 200: 1 to 20: 1, more preferably 100: 1. 100: 3. When the content ratio of the carboxylic acid polymer is too low, the effect of combining the olefin-acid copolymer and the carboxylic acid polymer is not sufficiently exhibited. Conversely, when the content ratio of the carboxylic acid polymer is excessive, This is because the olefin-acid copolymer and the carboxylic acid polymer are phase-separated in the surface treatment composition, so that a uniform resin film may not be formed, and the alkali resistance may be lowered.

  The resin component includes an oxazoline group-containing copolymer. The oxazoline group-containing copolymer forms a dense hard film by crosslinking reaction of the oxazoline group with the carboxyl group of the olefin-acid copolymer or carboxylic acid polymer. And has the effect of increasing the adhesion to the substrate and the top coat film. Further, since the reaction between the oxazoline group and the carboxyl group proceeds even at room temperature, there is an advantage that the drying temperature after coating the surface treatment composition can be lowered. Furthermore, even if an oxazoline group-containing copolymer is added, the fluidity (viscosity) and wettability of the surface treatment composition are not deteriorated, and the mechanical stability is also good.

  As the oxazoline group-containing copolymer, “Epocross (registered trademark)” manufactured by Nippon Shokubai Co., Ltd. whose main chain is styrene / acryl is suitable. In particular, the emulsion type “Epocross (registered trademark) K” series is preferable, and the grades are K-2010E (Tg: −50 ° C.), K-2020E (Tg: 0 ° C.) and K-2030E (Tg: 50 ° C.). ) Epocros K-2030E is most preferable for obtaining a hard film.

  In the resin component, in order to improve the hardness of the resin film, the oxazoline group-containing copolymer is 1 to 9 parts by mass with respect to a total of 100 parts by mass of the olefin-acid copolymer and the carboxylic acid polymer. . A preferable lower limit is 2 parts by mass, and a more preferable lower limit is 3 parts by mass. When the amount of the oxazoline group-containing copolymer exceeds 9 parts by mass, the effect of improving the film hardness is saturated and the paintability is deteriorated. A preferable upper limit is 6 parts by mass, and a more preferable upper limit is 4 parts by mass.

  As described above, the resin component includes an olefin-acid copolymer, a carboxylic acid polymer, and an oxazoline group-containing copolymer. A resin component is 40-5 mass parts with respect to 60-95 mass parts of inorganic components, and the sum total of both is 100 mass parts. When the amount of the resin component exceeds 40 parts by mass, the amount of the inorganic component is decreased, the hardness of the resin film is insufficient, and it becomes difficult to reduce the thickness. In addition, since the specific gravity of the film does not increase so much, it becomes impossible to settle the film residue in the coolant bath, and the effect of suppressing the accumulation on the surface of the draining pad is insufficient, resulting in operability and product shape. It is not preferable because it deteriorates. However, when the resin component is less than 5 parts by mass, the leveling property of the surface treatment composition is deteriorated, causing troubles such as occurrence of repellency when applied to a metal plate, and a normal film cannot be formed. Further, the film becomes too hard and brittle, and the corrosion resistance and the like deteriorate. In a total of 100 parts by mass of the inorganic component and the resin component, the resin component is more preferably 5 to 20 parts by mass, and further preferably 10 to 15 parts by mass.

  The surface treatment composition of the present invention further contains a glycidyl group-containing silane coupling agent. When a silane coupling agent is used, the adhesion between the metal and the resin film is improved, and the corrosion resistance is also improved accordingly. In particular, a glycidyl group-containing silane coupling agent has high reactivity and has a large effect of improving corrosion resistance and alkali resistance. Moreover, the surface treatment composition of the present invention does not need to contain an acidic compound (for example, a phosphoric acid compound, a nitric acid compound, and a fluorine compound) for the purpose of etching the surface of the metal plate. This is because the adhesion of the resin film can be improved by the silane coupling agent without etching the surface of the metal plate. The surface treatment composition not containing an acidic compound for the purpose of etching has improved stability and can form a good resin film. Furthermore, when a silane coupling agent is added, the composition is used when the surface treatment composition is used in a circulating manner by a spray ringer method (application method in which the surface treatment composition is sprayed on the surface of the metal plate and then squeezed with a roll). The effect which suppresses the foaming resulting from the surfactant in a thing also expresses.

  Glycidyl group-containing silane coupling agents include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxymethyldimethoxysilane, β- (3,4-epoxycyclohexyl) Examples include ethyltrimethoxysilane.

  The amount of the silane coupling agent in the surface treatment composition is 7 parts by mass or more, preferably 9 parts by mass or more, more preferably 11 parts by mass or more, with respect to 100 parts by mass in total of the inorganic component and the resin component. 35 parts by mass or less, preferably 30 parts by mass or less, more preferably 25 parts by mass or less. When the amount of the silane coupling agent is less than 7 parts by mass, the resin film adhesion and the corrosion resistance are lowered. However, when it exceeds 35 parts by mass, the stability of the surface treatment composition is lowered, causing gelation and precipitation of colloidal silica, and increasing the cost.

  The surface treatment composition of the present invention further contains metavanadate. Metavanadate is also eluted like colloidal silica, thereby suppressing the dissolution / elution of the metal plate and improving the corrosion resistance. Metavanadate particularly exhibits an effect of improving the corrosion resistance of the buttocks and end faces. In order to exhibit this effect effectively, it is good to use 0.5-7 mass parts of metavanadates with respect to a total of 100 mass parts of an inorganic component and a resin component. If the amount is less than 0.5 parts by mass, the effect of improving the corrosion resistance becomes insufficient, but even if added in excess of 7 parts by mass, the effect of improving the corrosion resistance is saturated, and the coating film adhesion and the resin film adhesion are reduced. Moreover, the stability of the surface treatment composition is also deteriorated. As for the amount of metavanadate, 4-6 mass parts is more preferable. In addition, the suitable amount of this metavanadate is a V element conversion amount.

Examples of the metavanadate include sodium metavanadate (NaVO ₃ ), ammonium metavanadate (NH ₄ VO ₃ ), and potassium metavanadate (KVO ₃ ), and one or more of these can be used. These metavanadates are commercially available and can be easily obtained.

  The surface treatment composition of the present invention may further contain a carbodiimide group-containing compound. A carbodiimide group reacts with a carboxyl group in an olefin-acid copolymer and a carboxylic acid polymer. Therefore, by using a carbodiimide group-containing compound, the amount of carboxyl groups in the resin film can be reduced and the alkali resistance can be improved. In the present invention, one or more carbodiimide group-containing compounds can be used.

  Carbodiimide group-containing compounds include isocyanates such as hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (HXDI), 4,4-diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI). Can be produced by heating in the presence of a carbodiimidization catalyst, and can be made aqueous (water-soluble, water-emulsifiable or water-dispersible) by modification. When the surface treatment composition is aqueous, an aqueous carbodiimide group-containing compound is preferable. A compound containing a plurality of carbodiimide groups in one molecule is preferable. When a plurality of carbodiimide groups are contained in one molecule, corrosion resistance and the like can be further improved by a crosslinking reaction with a carboxyl group in the resin component.

  Examples of commercially available polycarbodiimide compounds include N, N-dicyclohexylcarbodiimide, N, N-diisopropylcarbodiimide and the like, and polycarbodiimides (polymers having a plurality of carbodiimide groups in one molecule). Mention may be made of the “Carbolite®” series. The grades of “Carbolite (registered trademark)” include water-soluble “SV-02”, “V-02”, “V-02-L2”, “V-04” and emulsion type “E-01”. , “E-02” and the like are preferable.

  The amount of the carbodiimide group-containing compound is set according to the amounts of the olefin-acid copolymer and carboxylic acid polymer which are crosslinking partners. That is, when the total of the olefin-acid copolymer and the carboxylic acid polymer is 100 parts by mass, the amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and more preferably 100 parts by mass. Preferably it is 8 mass parts or more. On the other hand, when the amount of the carbodiimide group-containing compound is excessive, the effect of the combination of the olefin-acid copolymer and the carboxylic acid polymer is lowered. Further, when an aqueous carbodiimide group-containing compound is excessively used in an aqueous surface treatment composition, it may adversely affect water resistance and corrosion resistance. From such a viewpoint, the amount of the carbodiimide group-containing compound is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 16 parts by mass or less with respect to 100 parts by mass.

  The surface treatment composition of the present invention is a wax, a cross-linking agent, a diluent, an anti-skinning agent, a surfactant, an emulsifier, a dispersant, a leveling agent, an antifoaming agent, and a penetrating agent as long as the effects of the present invention are not impaired. , Film-forming aids, dyes, pigments, thickeners, lubricants and the like can also be contained.

  The surface treatment composition of the present invention may be either a solvent-based composition or an aqueous composition that can be applied to the surface of a metal plate, but is preferably an aqueous composition from the viewpoint of environmental problems. The surface treatment composition is an organic solvent (in the case of a solvent-based composition) or water, preferably deionized water (in the case of an aqueous composition), an olefin-acid copolymer, a carboxylic acid polymer, lithium silicate, colloidal silica. , A silane coupling agent, a metavanadate, an oxazoline group-containing copolymer, and, if necessary, a carbodiimide group-containing compound or other components may be blended in a predetermined amount and stirred.

  When preparing a surface treatment composition, a part of a silane coupling agent and a carbodiimide group-containing compound are added to an emulsion (emulsion) of an olefin-acid copolymer and a carboxylic acid polymer, and these mixtures are added. It is preferable to prepare and add lithium silicate, colloidal silica, the remaining glycidyl group-containing silane coupling agent, metavanadate, and oxazoline group-containing copolymer in this order. When an oxazoline group-containing copolymer is directly added to and mixed with an olefin-acid copolymer and a carboxylic acid polymer, gelation may occur, and when a metavanadate is added prior to the silane coupling agent, The reaction of the ring agent may be suppressed. The silane coupling agent is preferably added in two or more portions as described above. The silane coupling agent added first contributes to the refinement of the emulsion particles and the resulting improvement in the density of the resin film. The silane coupling agent added later ensures adhesion to the metal plate and film characteristics. It is because it contributes to the improvement of.

  You may heat at the time of stirring the said component. In particular, when the olefin-acid copolymer is emulsified in the presence of a carboxylic acid polymer, it is preferably heated. However, it is better not to heat after blending the oxazoline group-containing copolymer. This is to avoid the gelation of the surface treatment composition due to the reaction of the oxazoline group-containing copolymer, the olefin-acid copolymer, and the carboxylic acid polymer.

  When producing an aqueous surface treatment composition, it is preferable to emulsify the olefin-acid copolymer which is the main component of the resin component. The olefin-acid copolymer can be emulsified by using an emulsifier or neutralizing a carboxyl group in the copolymer. If an emulsifier is used, the average particle diameter of the aqueous emulsion of an olefin-acid copolymer can be reduced, and the film-forming property and thereby the density of the resin film can be improved.

  However, it is preferable to neutralize and emulsify the carboxyl group in the olefin-acid copolymer. By neutralizing and emulsifying carboxyl groups, the amount of emulsifier used can be reduced, or no emulsifier can be used, and the adverse effect of the emulsifier on the water resistance and corrosion resistance of the resin film can be reduced or eliminated. It is. When neutralizing the carboxyl group in the olefin-acid copolymer, a base of preferably about 0.5 to 0.95 equivalent, more preferably about 0.6 to 0.8 equivalent is used with respect to the carboxyl group. It is preferable. If the degree of neutralization is too small, the emulsifying property will not be improved so much. On the other hand, if the degree of neutralization is too large, the amount of carboxyl groups that react with the oxazoline group-containing copolymer will decrease, resulting in an adverse effect on corrosion resistance and the like. In some cases, the viscosity of the composition containing the olefin-acid copolymer may be too high.

As a base for neutralization, for example, a strong base composed of a group consisting of hydroxides of alkali metals and alkaline earth metals (for example, NaOH, KOH, Ca (OH) ₂ etc., preferably NaOH), aqueous ammonia, There may be mentioned primary, secondary and tertiary amines (preferably triethylamine). If a strong base such as NaOH is used, the emulsifying property is improved, but if it is too much, the corrosion resistance of the resin film may be lowered. On the other hand, an amine having a low boiling point (preferably an amine having a boiling point of 100 ° C. or lower under atmospheric pressure; for example, triethylamine) does not significantly reduce the corrosion resistance of the resin film. The reason for this may be that the low boiling point amine volatilizes when a resin film is formed by heating and drying after applying the surface treatment composition. However, since an amine has a small effect of improving emulsifiability, it is preferable to neutralize by combining the strong base and the amine. The optimal combination is a combination of NaOH and triethylamine. When a strong base and an amine are used in combination, the strong base is used in an amount of about 0.01 to 0.3 equivalents and the amine is used in an amount of 0.4 to 0.8 equivalents relative to the amount of carboxyl groups of the olefin-acid copolymer. It is preferable to use a degree.

  When an aqueous surface treatment composition is used, a small amount of an organic solvent may be added in order to reduce the interfacial tension and improve the wettability to the metal plate. Examples of the organic solvent for this purpose include methanol, ethanol, isopropanol, butanols, hexanol, 2-ethylhexanol, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol, propylene glycol and the like.

  There is no limitation in particular in solid content of a surface treatment composition, What is necessary is just to adjust according to the application | coating method of the surface treatment composition to a metal plate. The solid content of the surface treatment composition is generally about 5 to 20% by mass. For example, when the surface treatment composition is applied by a spray ringer method (an application method in which the surface treatment composition is sprayed on the surface of the metal plate and then squeezed with a roll), 10 About -18 mass% is suitable.

  There is no limitation in particular in the metal plate used by this invention, For example, a non-plating cold-rolled steel plate, hot-dip galvanized steel plate (GI), hot-dip galvanized steel plate (GA), electrogalvanized steel plate (EG), an aluminum plate, and A titanium plate etc. can be mentioned. Among these, it is preferable to apply this invention to the hot dip galvanized steel plate (GI) and the hot galvannealed steel plate (GA) which are not chromated.

  In the present invention, the method and conditions for forming the resin film on the metal plate are not particularly limited, and the surface treatment composition is applied to one or both surfaces of the metal plate surface by a known coating method, followed by heating and drying. A resin-coated metal plate can be manufactured. Examples of the method for applying the surface treatment composition include a curtain flow coater method, a roll coater method, a spray method, and a spray ringer method. Among these, the spray ringer method is preferable from the viewpoint of cost and the like. Moreover, there is no limitation in particular also in heat drying conditions, As heat drying temperature, about 50-120 degreeC, Preferably about 70-90 degreeC can be illustrated. An excessively high heat drying temperature is not preferable because the resin film deteriorates.

The adhesion amount of the resin film on the resin-coated metal plate is preferably 0.1 to 1 g / m ² , more preferably 0.3 to 0.6 g / m ² in terms of dry mass. When the adhesion amount is too small, it becomes difficult to cover the surface of the metal plate, and roll formability and corrosion resistance are greatly impaired. On the other hand, if the amount of adhesion increases, roll formability and corrosion resistance will be good, but the amount of film peeled off during roll forming will increase, so the amount of film residue deposited on the draining pad will increase, causing trouble. This is not preferable. The resin film of the present invention contains many inorganic components and has a large specific gravity. For this reason, compared with the conventional resin film rich in the resin component, even if the adhesion amount is the same, it has succeeded in thinning. This also contributes to the reduction of film residue.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and appropriate modifications are made within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

  The characteristic evaluation method used in the examples is as follows.

[Roll formability]
In order to examine the roll formability, the resin-coated metal plate was cut into 40 mm × 300 mm, and V-bent was performed at 90 degrees with a bender in a longitudinal direction of 200 mm. The end 100 mm was left unbent for setting on the chuck. This sample is set vertically in a tensile tester, a jig having a convex portion with a tip radius R = 1 mm is brought into contact with the upper end inside the V-bending part, and a flat plate die is brought into contact with the back surface of the V-bending part. The sample was pulled upward at 300 mm / min while applying a load of 2940 N (300 kgf) to the horizontal direction. The film attached to the jig is collected by attaching cellophane tape (manufactured by Nichiban Co., Ltd .; “Cellotape (registered trademark) product number No. 405” or less, simply referred to as tape) and then peeling off, and is applied to the V-bending sliding part. Also, the film was peeled off after applying the tape, and the film peeled off from the sliding part was collected. Both tapes were dissolved by heating in a mixed solution (1 + 1) of hydrochloric acid and the same amount of pure water. Using this sample solution, quantitative analysis of Zn element was performed by inductively coupled plasma (ICP) emission spectrometry, and the following criteria were evaluated. The analysis of the Si element, which is a film component, was not performed because the absolute amount of peeling was small and the analysis sensitivity was insufficient and an error was likely to occur. In addition, the present inventors have confirmed that this roll formability evaluation method is highly correlated with roll formability in an actual machine.
A: Zn concentration in sample solution is less than 2 mg / l. O: Zn concentration in sample solution is 2 mg / l or more and less than 5 mg / l. Δ: Zn concentration in sample solution is 5 mg / l or more and less than 10 mg / l. Zn concentration of 10mg / l or more

[Flat corrosion resistance]
A salt spray test was carried out based on JIS Z2371, and the time until the white rust occurrence rate (100 × area where white rust occurred / total area of the test material) reached 5% was measured.

[Cross-cut corrosion resistance]
In order to investigate the corrosion resistance of the buttocks, a cross cut was put into the test material with a cutter knife, a salt spray test was performed based on JIS Z2371, and the time until the white rust occurrence rate reached 10% was measured.

[Corrosion resistance in JASO cycle test]
A JASO cycle test was conducted based on JIS H8502. 1 cycle is salt spray (temperature 35 ° C. × 2 hours) → drying (temperature 35 ° C. × humidity 30% or less × 4 hours) → wetting (temperature 50 ° C. × humidity 95% or more × 2 hours) (each transition time) including.). After carrying out 15 cycles, the white rust occurrence rate was evaluated according to the following criteria.
◎: White rust occurrence rate of less than 5% ○: White rust occurrence rate of 5% to less than 10% △: White rust occurrence rate of 10% to less than 20% ×: White rust occurrence rate of 20% or more

[Coating film adhesion]
Bar coating was applied to a resin-coated metal plate so that the coating thickness after drying the acrylic paint (top coating) was 20 μm, followed by baking at 160 ° C. for 20 minutes for post-coating. Subsequently, after immersing this test material in boiling water for 1 hour, taking it out and leaving it to stand for 1 hour, 100 mm of a 1 mm square grid was cut with a cutter knife, and a tape peeling test was carried out on this. The coating film adhesion was evaluated according to the following criteria based on the number of remaining squares.
A: Coating film remaining rate 100%
○: Coating film remaining rate 99% or less to 90% or more Δ: Coating film remaining rate 89% or less to 80% or more ×: Coating film remaining rate 79% or less

Example 1
To an autoclave having an emulsification facility with an internal capacity of 1.0 L equipped with a stirrer, a thermometer and a temperature controller, an ethylene-acrylic acid copolymer ("Primacol (registered trademark) 5990I" manufactured by Dow Chemical Co., Ltd.), derived from acrylic acid Structural unit: 20% by mass, mass average molecular weight (Mw): 20,000, melt index: 1300, acid value: 150) 200.0 g, polymaleic acid aqueous solution (Non-Paul (registered trademark) PMA-50W manufactured by NOF Corporation) , Mw: about 1100 (polystyrene conversion), 50% by mass product) 8.0 g, triethylamine 35.5 g (0.63 equivalent to the carboxyl group of the ethylene-acrylic acid copolymer), 6.9 g of 48% NaOH aqueous solution (0.15 equivalent to the carboxyl group of the ethylene-acrylic acid copolymer), tall oil fatty acid (harima Narusha made "HARTALL FA3") 3.5 g, and sealed with ion exchange water 792.6G, after 3 hours stirred at high speed 0.99 ° C. and 5 atm, and cooled to 30 ° C.. Next, 10.4 g of glycidyl group-containing silane coupling agent (Momentive Performance Materials (former name: GE Toshiba Silicone) “TSL8350”, γ-glycidoxypropyltrimethoxysilane), carbodiimide group-containing compound (Nisshinbo Co., Ltd.) “Carbodilite (registered trademark) SV-02” manufactured by Polycarbodiimide, Mw: 2,700, solid content 40 mass%) 31.2 g and ion-exchanged water 72.8 g were added and stirred for 10 minutes. 1 (solid content 20.3% by mass, measured according to JIS K6833).

Lithium silicate having a SiO ₂ / Li ₂ O molar ratio of 4.5 (“Lithium silicate 45” manufactured by Nissan Chemical Industries) and colloidal silica (“Snowtex (registered trademark) XS” manufactured by Nissan Chemical Industries, Ltd.), surface area average The particle size (catalog value): 4 to 6 nm) was mixed so that the mass ratio was 90:10 to prepare an inorganic component.

  Emulsion No. After adding the above inorganic components to 1 and mixing them well, a glycidyl group-containing silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical Co., Ltd., γ-glycidoxypropyltriethoxysilane), then sodium metavanadate (Emerging) "Sodium metavanadate" manufactured by Chemical Industry Co., Ltd.) was added. To this mixture, an oxazoline group-containing copolymer (“Epocross (registered trademark) K-2030E” manufactured by Nippon Shokubai Co., Ltd., solid content: 40% by mass) was further added. 1 was prepared.

  The amount of the resin component in Table 1 is the emulsion No. This corresponds to the amount of the mixture of the total solid content in 1 and the oxazoline group-containing copolymer. The oxazoline group-containing copolymer was added in an amount of 5 parts by mass with respect to 100 parts by mass of the total amount of the ethylene-acrylic acid copolymer and polymaleic acid. A total of 100 parts by mass of the inorganic component and the resin component was added so that the glycidyl group-containing silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) was 15 parts by mass and sodium metavanadate was 5 parts by mass.

As the metal plate, an alkali degreased hot dip galvanized steel plate (Zn adhesion amount 45 g / m ² ) was used. 1 was applied to by a bar coating (bar No.3), and about 12 seconds heat dried at a sheet temperature 90 ° C., the resin film coating weight of the resin coated metal sheet of 0.5 g / m ² No. 1 was produced.

Examples 2-8 and Comparative Examples 1-4
In the same manner as in Example 1 except that the ratio of the inorganic component and the resin component was changed as shown in Table 1, the surface treatment composition No. 2 to 12 were prepared, and the resin-coated metal plate No. 2-12 were produced. Resin coated metal plate No. 2 to 8 are Examples 2 to 8, resin-coated metal plate Nos. 9 to 12 are Comparative Examples 1 to 4 in which the mass ratio between the inorganic component and the resin component deviates from the requirement of claim 1 of the present invention. The evaluation results are also shown in Table 1.

Examples 9-13 and Comparative Examples 5-7
Emulsion No. As shown in Table 2, the amount of the oxazoline group-containing copolymer relative to 100 parts by mass (solid content) of the ethylene-acrylic acid copolymer and polymaleic acid in 1 was changed. The ratio of the inorganic component and the resin component was constant at 90 parts by mass: 10 parts by mass. Otherwise, a resin-coated metal plate was produced in the same manner as in Example 1. The evaluation results are shown in Table 2.

Examples 14-20 and Comparative Examples 8-11
The ratio of the inorganic component and the resin component is 90 parts by mass: 10 parts by mass, and the amount of the post-added glycidyl group-containing silane coupling agent (“KBM403” manufactured by Shin-Etsu Chemical Co., Ltd.) relative to the total of 100 parts by mass (solid content) of both Changes were made as shown in Table 3. Otherwise, a resin-coated metal plate was produced in the same manner as in Example 1. The evaluation results are shown in Table 3.

Examples 21-29 and Comparative Examples 12-15
The ratio of the inorganic component and the resin component was 90 parts by mass: 10 parts by mass, and the type and amount of metavanadate with respect to 100 parts by mass (solid content) of both were changed as shown in Table 4. Otherwise, a resin-coated metal plate was produced in the same manner as in Example 1. The evaluation results are shown in Table 4.

Examples 30 to 33 and Reference Examples 1 to 3
The amount ratio of lithium silicate and colloidal silica in the inorganic component was changed as shown in Table 5. The ratio of the inorganic component and the resin component was constant at 90 parts by mass: 10 parts by mass. Otherwise, a resin-coated metal plate was produced in the same manner as in Example 1. Examples 30 to 33 are examples in which the amount ratio of lithium silicate to colloidal silica satisfies the preferred range of the present invention, and in Reference Examples 1 to 3, the amount ratio of lithium silicate to colloidal silica is the preferred range of the present invention. This is an example that deviates from the above.

Examples 34 to 35 and Reference Examples 4 to 5
The surface area average particle diameter (nm) of colloidal silica in the inorganic component was changed as shown in Table 6. The ratio of the inorganic component and the resin component was constant at 90 parts by mass: 10 parts by mass. Otherwise, a resin-coated metal plate was produced in the same manner as in Example 1. Examples 34 to 35 are examples in which the surface area average particle diameter of colloidal silica satisfies the preferable range of the present invention, and Reference Examples 4 to 5 are examples in which the surface area average particle diameter deviates from the preferable range of the present invention. The colloidal silica of Reference Example 4 is “Snowtex (registered trademark) XL” manufactured by Nissan Chemical Industries, Ltd. The colloidal silica of Reference Example 5 is “Snowtex (registered trademark) ZL” manufactured by Nissan Chemical Industries, Ltd. .

Examples 36-43 and Reference Examples 6-8
A resin-coated metal plate was produced in the same manner as in Example 1 except that the ratio of the inorganic component to the resin component was constant at 90 parts by mass and 10 parts by mass, and the amount of the resin film adhered was changed as shown in Table 7. . Examples 36 to 43 are examples in which the coating amount satisfies the preferable range of the present invention, and Reference Examples 6 to 8 are examples in which the coating amount deviates from the preferable range of the present invention. In addition, the zinc adhesion amount of the alloyed hot-dip Zn-plated steel sheet was 45 g / m ² and was used after alkali degreasing as in Example 1.

Examples 44 to 46 and Reference Examples 9 to 10
The ratio of the inorganic component and the resin component was constant at 90 parts by mass: 10 parts by mass, and the SiO ₂ / Li ₂ O molar ratio of lithium silicate was changed as shown in Table 8 in the same manner as in Example 1. A resin-coated metal plate was produced. Examples 44 to 46 are examples in which the SiO ₂ / Li ₂ O molar ratio satisfies the preferable range of the present invention, and in Reference Examples 9 to 10, the SiO ₂ / Li ₂ O molar ratio deviates from the preferable range of the present invention. It is an example. It should be noted that the SiO ₂ / Li ₂ O molar ratio is 2.6 and 8.0 of those is a manufacturer prototype, commercially available have not been.

  As is clear from Tables 1 to 8, the examples of the present invention were excellent in roll formability, good corrosion resistance, and excellent coating film adhesion.

  Since the resin-coated metal plate of the present invention is excellent in corrosion resistance and roll formability, it can be suitably used for automobiles, home appliances, building materials and the like.

Claims (5)

A resin-coated metal plate provided with a resin film obtained from a surface treatment composition,
60 to 95 parts by mass of an inorganic component composed of lithium silicate and colloidal silica, and a total of olefin-α, β-unsaturated carboxylic acid copolymer and α, β-unsaturated carboxylic acid polymer While containing 5 to 40 parts by mass of a resin component containing 1 to 9 parts by mass of an oxazoline group-containing copolymer with respect to 100 parts by mass,
Roll formability characterized by further containing 7 to 35 parts by mass of a glycidyl group-containing silane coupling agent and 0.5 to 7 parts by mass of metavanadate with respect to 100 parts by mass in total of the inorganic component and the resin component. Excellent resin-coated metal plate.   The resin-coated metal plate according to claim 1, wherein the lithium silicate and colloidal silica in the surface treatment composition have a mass ratio of 95: 5 to 80:20.   The resin-coated metal sheet according to claim 1 or 2, wherein the colloidal silica has a surface area average particle diameter of 4 to 20 nm.   When the surface treatment composition is 100 parts by mass when the total of the olefin-α, β-unsaturated carboxylic acid copolymer and α, β-unsaturated carboxylic acid polymer in the composition is 100 parts by mass. The resin-coated metal plate according to any one of claims 1 to 3, further comprising a carbodiimide group-containing compound at a ratio of 0.1 to 30 parts by mass with respect to parts. The resin-coated metal sheet according to any one of claims 1 to 4, wherein an adhesion amount of the resin film is 0.1 to 1 g / m ² in terms of dry mass.