JP5135669B2 - Manufacturing method of painted metal - Google Patents

Description

The present invention relates to a method for producing a coated metal material which does not contain hexavalent chromium having high environmental impact, has extremely high corrosion resistance, and has good workability.

  In various fields such as home appliances, automobiles, and building materials, a technique of performing chromate treatment on steel sheets and surface-treated steel sheets is generally used for the purpose of imparting rust prevention or paint adhesion to the upper layer. However, since the chromate-treated film usually contains hexavalent chromium, which has a high environmental impact, there has been a growing demand for hexavalent chromium-free coatings in recent years, and some have already begun to be completely abolished. There is also an industry.

  In response to this trend, various chromate film alternative technologies have been studied. For example, as disclosed in Patent Document 1, a technique mainly composed of an inorganic compound that is treated with a treatment liquid containing orthophosphoric acid, an aluminum-based sol, and a metal-based hydrosol has been studied. However, such inorganic coatings are prone to wrinkles during processing and have the problem of limited use. In addition, for example, the corrosion resistance against sodium chloride has not yet been sufficiently satisfactory for chromate treatment.

  Furthermore, along with the recent trend toward diversification and tightening of required performance, it is becoming difficult to cope with the conventional technology. In particular, compatibility between the moldability and long-term corrosion resistance and the conflicting properties such as solvent resistance and alkali resistance has been demanded. In response to such demands, coatings mainly composed of organic compounds have excellent formability in addition to the effect of blocking the corrosive environment by the coatings, and are promising as chromium-free coatings. Among them, a film mainly composed of a urethane resin having strong properties as a film and good adhesion is promising as a chromate-free film.

  Conventionally, several techniques based on a urethane resin film have been disclosed. For example, in Patent Document 2, as an example of excellent film adhesion after processing, a technique in which a film layer mainly composed of a composite material or mixed material of urethane resin and silicon dioxide is provided, and in Patent Document 3, metal phosphate is used. A treatment liquid technology in which an aqueous urethane resin and an oxycarboxylic acid compound are mixed is disclosed. However, since these conventional techniques are based on a general urethane resin, they have a problem in that they have high hydrophilicity and are easily wetted with water, resulting in long-term corrosion protection of metals.

  Moreover, as an example for the purpose of rust prevention, for example, Patent Document 4 discloses a film technology in which a silane coupling agent is added to a urethane resin into which a hydrophilic component is introduced, for example, Patent Document 5 discloses an aqueous polyurethane resin and an aqueous solution. The technology of the antirust coating agent which mixed the aqueous silica, the silane coupling agent, the thiocarbonyl group containing compound, the phosphate ion with the mixture of polyolefin resin is disclosed. However, as in the case of Patent Document 2, since the hydrophilicity is high, there is a concern about long-term corrosion resistance, the glass transition point is not so high, and strict performance is easily secured such as being easily wrinkled during molding. Had the problem of becoming difficult.

  Further, the technique based on the two-stage processing as disclosed in Patent Document 6 can secure performance by the effect of the two-layer configuration, but has a problem that it is costly and economical. Therefore, a treatment film by one-step treatment has been desired.

Japanese Examined Patent Publication No. 53-47774 Japanese Patent Publication No. 6-7950 JP 2001-181855 A JP 2001-59184 A JP 2001-164182 A JP 2001-89874 A

Therefore, the present invention has been made in view of such problems, focusing on the urethane-based resin film as a surface treatment material that can be substituted for the chromate treatment material, and solving the above-mentioned problems such as corrosion resistance and workability, The objective is to provide a method for producing a coated metal material which is advantageous in terms of workability and cost by processing in a single layer while achieving both performance.

Urethane resin films have strong cohesive strength and toughness, excellent durability, and favorable properties as metal coating materials. However, in general, urethane resin has many hydrophilic groups, so it is easily wetted by water, and has a problem in terms of long-term corrosion protection of metals. The inventors have formed to solve this problem, resin properties, and the results were examined in detail the film structure of the various additives, a urethane-based resin film that suppresses parent aqueous to the surface of the metal material As a result, it was found that the corrosion resistance and alkali resistance are drastically improved. In particular, it was found that a urethane-based resin film having a high glass transition point and a high elastic modulus is excellent in anticorrosion properties, hardly scratches during molding, and excellent in anticorrosion properties after molding. Furthermore, it has been found that it also has a good effect on solvent rubbing resistance. In general, increasing the concentration of the hydrophilic group in the urethane resin also improves the glass transition point and elastic modulus and may improve the performance as a coating material. In that case, however, the hydrophilicity also increases, Corrosion protection does not necessarily improve.

  Therefore, in the present invention, a urethane resin containing silanol groups in the resin skeleton of the urethane resin is used in the resin composition of the previous stage constituting the film, and a crosslinked structure of siloxane bonds is formed by a dehydration condensation reaction between the silanol groups. The film structure is designed to form. As a result, the hydrophobicity can be further increased, and the mechanical properties of the film by introducing a cross-linked structure (for example, the physical strength of the film such as the tensile strength (breaking strength) and elongation of the film) can be improved. . Similarly, the hydrophobicity of the film can be increased by introducing a crosslinked structure also by a crosslinking reaction between a silanol group and another functional group.

  Furthermore, by introducing a specific cross-linking agent in the urethane resin, the cross-linking reaction can be efficiently performed at a lower baking temperature, and the characteristics of the cross-linking agent itself can be added to the film. That is, the cross-linking agent may also be a polymer, and in that case, the properties of the cross-linking agent polymer itself can be added to the film in addition to the action of cross-linking the resin. Specifically, the film adhesion and solvent resistance may be improved by the polymer of the crosslinking agent skeleton and the organic polymer bonded thereto. The effect is most remarkable when the crosslinking agent is a crosslinking agent comprising any one of water-soluble isocyanate, carbodiimide group-containing compound, oxazoline group-containing compound, and organic titanate, or a mixture of two or more.

  Further, by containing silicon oxide and a phosphoric acid compound in the urethane resin film, the film properties such as better corrosion resistance can be further enhanced. Silicon oxide and phosphoric acid compounds are mostly hydrophilic compounds, but it is possible to ensure an appropriate contact angle by controlling the addition amount within a predetermined range.

  Furthermore, by appropriately adding a lubricity-imparting agent, a product with a low coefficient of friction can be obtained while maintaining good performance, and a surface-treated metal material excellent in workability can be obtained. In particular, the lubricity imparting material has many hydrophobic compounds and is effective in increasing the contact angle.

  The coated metal material of the present invention found above is particularly effective when the metal material is a galvanized steel sheet. The white metal after 240 hours in the salt spray test defined in JIS-Z-2371. High corrosion resistance with a rust generation area ratio of 5% or less. In addition, when the metal material is a galvanized steel sheet, the effect is remarkable when the salt spray test specified in JIS-Z-2371 is performed after alkaline degreasing, and the white rust generation area ratio after 120 hours. Exhibits high corrosion resistance of 5% or less.

  Furthermore, in the method for producing a coated metal material according to the present invention, a specific relationship is established between the glass transition temperature Tg (° C.) of the resin, the ultimate plate temperature PMT (° C.), and the drying time t (second). It has also been found that by producing a baked or painted metal material, a urethane resin film having a large contact angle is obtained and the best characteristics are exhibited.

That is, the gist of the present invention is that
(1) on a metal material surface, have a silanol group in the resin backbone, water-dispersible or water-soluble elastic modulus at 20 ° C. of glass transition temperature of 100 ° C. or higher, or the resin alone film is not less than 0.5GPa The first step of applying a paint containing at least a porous polyurethane resin; the relationship between the glass transition temperature Tg (° C.) of the polyurethane resin and the ultimate temperature PMT (° C.) of the metal material during baking is PMT-Tg ≧ 10 (° C.) is satisfied, and the relationship between the glass transition temperature Tg (° C.) of the polyurethane resin, the baking reached material temperature PMT (° C.), and the baking time t (seconds) is expressed by t × log (PMT a second step of baking and curing under conditions satisfying the /Tg)≧0.5; look including the said coating, characterized by containing a phosphoric acid compound, a method of manufacturing a coated metal material,
(2) The polyurethane resin contains a carboxyl group or a sulfonic acid group, and when the polyurethane resin is dispersed or dissolved in the paint, the carboxyl group or the sulfonic acid group is neutralized. (1) a method for producing a painted metal material,
(3) The method for producing a coated metal material according to (1), wherein the paint contains silicon oxide,
(4) The method for producing a coated metal material according to (3), wherein the silicon oxide content is 2% by mass or more and 20% by mass or less as a silicon amount with respect to the total solid content of the paint,
( 5 ) The content of the phosphoric acid compound is 0.1% by mass or more and 10% by mass or less as the amount of phosphorus with respect to the total solid content of the paint, The painted metal material according to ( 1 ) Production method,
( 6 ) The coating material contains at least one selected from the group consisting of a water-soluble isocyanate, a carbodiimide group-containing compound, an oxazoline group-containing compound, and an organic titanate as a crosslinking agent for a urethane resin. ) Or (3 ), a method for producing a painted metal material,
( 7 ) The method for producing a coated metal material according to (1), (3 ) or (6) , wherein the paint further contains a lubricity imparting agent,
( 8 ) The method for producing a coated metal material according to ( 7 ), wherein the content of the lubricity-imparting agent is 0.2 to 30% by mass with respect to the total solid content of the paint,
( 9 ) The method for producing a coated metal material according to (1), wherein the metal material is a zinc-based plated steel sheet,
It is.

According to the present invention, a coated metal material having a performance capable of substituting conventionally used chromate, which is free from hexavalent chromium having a high environmental load, is excellent in various properties such as corrosion resistance, workability and adhesion. The manufacturing method of can be provided. Therefore, the coated metal material of the present invention is very promising as a future environment-friendly material, and greatly contributes to each industrial field.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  In the coated metal material according to the present invention, a urethane-based resin film having a contact angle with water at 20 ° C. of 60 degrees or more is formed on the outermost surface. By applying a urethane-based resin film with suppressed hydrophilicity so that the contact angle of water is 60 degrees or more, it is possible to stably achieve both long-term corrosion resistance and alkali degreasing resistance. When the contact angle is less than 60 degrees, there may be a large variation in performance depending on the configuration and state of the film, which is not preferable.

  As a means for obtaining such a urethane-based resin film having a high contact angle while ensuring the film performance, one is to use a polyurethane resin having a high contact angle when it is used alone, and another. One is to increase the glass transition point or elastic modulus of the urethane resin film. Specifically, when the contact angle of water at an air temperature of 20 ° C. is 60 degrees or more and the glass transition temperature of the urethane-based resin film is 100 ° C. or more, or the elastic modulus at 20 ° C. is 0.5 GPa or more, high contact is obtained. In addition to obtaining corners, it is possible to obtain a film having excellent scratch resistance, solvent resistance, and corrosion resistance after processing. If the glass transition temperature or elastic modulus of the film is less than the above value, the workability may decrease and the corrosion resistance after processing may decrease. The glass transition point or elastic modulus of the urethane resin film can be increased by changing the resin structure or adding a predetermined additive.

  Such an action is also effective in the case of a mixed resin film mainly composed of a polyurethane resin. In that case, the same effect can be expected if the value of the entire contact angle is 60 degrees or more. When the proportion of the polyurethane resin in the resin component exceeds 50%, the characteristics of the polyurethane resin in the mixed resin film become dominant, and the above-described effects are exhibited. Examples of the mixed resin other than the urethane resin include an epoxy resin, an acrylic resin, a polyester resin, a polyolefin resin, and a phenol resin. These are resins that can be mixed as a treatment liquid with a polyurethane resin, and one or two or more kinds can be mixed with a polyurethane resin and used as long as the contact angle condition after the formation of the mixed film is satisfied.

  As a method of forming a urethane-based resin film having the above characteristics, a compound having at least two active hydrogen groups per molecule and a polyisocyanate compound having at least two isocyanate groups per molecule are reacted. And a method of producing a resin composition by dissolving or dispersing in water, applying a surface treatment liquid mixed with various additives to a metal material, and baking and drying.

  Examples of the compound having at least two active hydrogen groups per molecule constituting the polyurethane prepolymer include compounds having amino groups, hydroxyl groups, and mercapto groups as compounds having active hydrogen groups. In view of the reactivity, a polyol compound having a hydroxyl group is preferable because of its high reaction rate. Examples of the polyol compound having at least two active hydrogen groups per molecule include polycarbonate polyol, polyester polyol, polyether polyol, polyester amide polyol, acrylic polyol, polyurethane polyol, and mixtures thereof. Of these, polycarbonate polyols, polyester polyols, and polyether polyols are preferable for ensuring processability and ensuring a high elastic modulus.

  Examples of the compound having at least two isocyanate groups per molecule include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2 , 3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate and the like, for example, 1 , 3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethyl Hexyl isocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,2-bis (isocyanatomethyl) cyclohexane, 1,4-bis ( Alicyclic diisocyanates such as isocyanatomethyl) cyclohexane and 1,3-bis (isocyanatomethyl) cyclohexane, for example, m-xylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4′-toluidine diisocyanate, Aromatic diisocyanates such as anisidine diisocyanate, 4,4′-diphenyl ether diisocyanate and the like, for example, ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, Aro-aliphatic diisocyanates such as ω′-diisocyanate-1,4-diethylbenzene, for example, triphenylmethane-4,4′-4 ″ -triisocyanate, 1,3,5-triisocyanatebenzene, 2,4, Polyisocyanate monomers such as triisocyanates such as 6-triisocyanate toluene, tetraisocyanates such as 4,4′-diphenyldimethylmethane-2,2 ′, 5,5′-tetraisocyanate, and the like polyisocyanates Monomers and dimers derived from monomers To polyisocyanate derivatives obtained from mer, burette, allophanate, carbodiimide, and the above polyisocyanate monomers, and low molecular weight polyols having a molecular weight of less than 200 such as ethylene glycol, propylene glycol, butylene glycol, etc. And adducts to the above polyisocyanate monomers such as polyester polyols, polyether polyols, polycarbonate polyols, polyester amide polyols, acrylic polyols, polyurethane polyols, and the like.

  Furthermore, as a means for obtaining a urethane resin film having a high contact angle while further ensuring film performance, (1) by using a polyurethane resin containing a silanol group in the resin film structure, Forming a crosslinked structure by forming siloxane bonds between each other; (2) using a polyurethane resin containing a silanol group in the resin film structure, and mixing other resins other than the polyurethane resin, And a water-affinity functional group X of another resin form a Si—O—X cross-linked structure, or (3) when silicon oxide is contained, the Si—O—Si bond with the surface is dried. There is a method of achieving the purpose by forming. Here, examples of the functional group X of the other resin when forming the Si—O—X crosslinked structure include a hydroxyl group, a carboxyl group, an amino group, an isocyanate group, and an epoxy group.

  The polyurethane resin containing a silanol group in the resin film structure is obtained by, for example, reacting a hydrolyzable silicon group-containing compound having at least one active hydrogen group in the molecule with a polyurethane prepolymer, It can be formed by dispersing or dissolving in water and hydrolyzing. The hydrolyzable silicon group is a group in which a hydrolyzable group that is hydrolyzed by moisture is bonded to a silicon atom. Specific examples of such a hydrolyzable group include a hydrogen atom, a halogen atom, an alkoxy group, an acyloxy group, an amino group, an amide group, an aminooxy group, a mercapto group, and the like. Of these, alkoxy groups are preferred because of their relatively low hydrolyzability and ease of handling. The above hydrolyzable group is usually bonded to one silicon atom in the range of 1 to 3, but the hydrolyzable silyl group after coating has reactivity, water resistance and solvent resistance. 2 to 3 are preferably bonded.

  The polyurethane prepolymer in this case is composed of a hydrolyzable silicon group-containing compound having at least one active hydrogen group in the molecule, a compound having at least two active hydrogen groups per molecule, and at least 2 per molecule. You may react with the compound which has an isocyanate group simultaneously.

  Examples of the hydrolyzable silicon group-containing compound having at least one active hydrogen group in the molecule include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltriethoxy. Silane, γ- (2-aminoethyl) aminopropyldimethoxysilane, γ- (2-aminoethyl) aminopropyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyldimethoxy Examples include silane, γ-aminopropyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltriethoxysilane, and γ-mercaptopropyldiethoxysilane. To contribute Cormorants regard, it is desirable to introduce silanol groups between molecules constituting a polyurethane resin and a hydrolyzable silicon group-containing compound having two or more active hydrogen groups are preferred.

  The content of silanol groups or Si—O bonds is 0.1 to 10 mass% in terms of silicon with respect to the total solid content of the polyurethane resin in order to give the polyurethane resin excellent crosslinking reactivity and performance. If it is less than 0.1% by mass, the effect tends to be low because it does not appropriately contribute to the crosslinking reaction, and if it exceeds 10% by mass, the effect is saturated and the stability of the treatment liquid is likely to be lowered. Preferably it is 0.5-5 mass%.

  In order to disperse the polyurethane resin in water, it is preferable to introduce a hydrophilic group into the polyurethane prepolymer. In order to introduce a hydrophilic group, for example, it has at least one active hydrogen group in the molecule and contains a hydrophilic group such as a carboxyl group, a sulfonic acid group, a sulfonate group, or a polyoxyethylene group. What is necessary is just to copolymerize a compound at the time of the said polyurethane prepolymer manufacture at least 1 or more types. Examples of such hydrophilic group-containing compounds include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxybenzoic acid, Carboxyl group-containing compounds such as 3,4-diaminobenzoic acid or derivatives thereof, or polyester polyols obtained by copolymerization thereof, maleic anhydride, phthalic anhydride, succinic anhydride, trimellitic anhydride, pyromellitic anhydride A carboxyl group-containing compound obtained by reacting a compound having an anhydride group such as an acid with a compound having an active hydrogen group or a derivative thereof such as 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5- Sulfonic acid-containing compounds such as sulfoisophthalic acid and sulfanilic acid, and these Derivatives, or these copolymerized polyester polyols obtained by the like.

  In order to dissolve or disperse the polyurethane resin well in water, a neutralizing agent is used. Examples of neutralizing agents that can be used in neutralization include tertiary amines such as ammonia, triethylamine, triethanolamine, triisopropanolamine, trimethylamine, and dimethylethanolamine, sodium hydroxide, potassium hydroxide, and calcium hydroxide. Basic substances such as alkali metal and alkaline earth metal hydroxides can be mentioned, but from the viewpoint of weldability, solvent resistance, and odor during welding, it is preferable to use a tertiary amine having a boiling point of 120 ° C. or higher. These neutralizing agents may be used alone or in a mixture of two or more. As a method for adding the neutralizing agent, the neutralizing agent may be added directly to the polyurethane prepolymer, or may be added to water when dissolved or dispersed in water. The addition amount of the neutralizing agent is 0.1 to 2.0 equivalents, more preferably 0.3 to 1.3 equivalents with respect to the carboxyl group. Even when a substituent other than a carboxyl group, such as a sulfonic acid group, is introduced as a hydrophilic group to be introduced into the polyurethane prepolymer, the neutralizing agent has substantially the same equivalent as in the case of a carboxyl group. What is necessary is just to add.

  Moreover, the method of devising a crosslinking agent and an additive is also mentioned as a means for obtaining a urethane-type resin film with a high contact angle while ensuring the film performance. Any crosslinking agent can be used as long as it is water-soluble or water-dispersible. Among these, one or more selected from water-soluble isocyanate compounds, carbodiimide group-containing compounds, oxazoline group-containing compounds, and organic titanate compounds are used. It is preferable.

  As a water-soluble isocyanate compound, for example, Bernock 5000 (manufactured by Dainippon Ink Co., Ltd.) is exemplified.

  Examples of the carbodiimide group-containing compound include Carbodilite V-02, V-02-L2, E-01, E-02, E-03A, and E-04 (manufactured by Nisshinbo Co., Ltd.). The

  Examples of the oxazoline group-containing compound include Epocros K-2010E, K-2020E, K-2030E, WS-500, and WS-700 (manufactured by Nippon Shokubai Co., Ltd.).

  Examples of organic titanates include ORGATIX TC-300 (dihydrokisbis (ammonium lactate) titanium; manufactured by Matsumoto Pharmaceutical Co., Ltd.), TC-400 (diisopropoxytitanium bis (triethanolaminate; manufactured by Matsumoto Pharmaceutical Co., Ltd.)), Etc. are exemplified.

  The preferred addition amount of these cross-linking agents depends on the acid value of the resin, but from the balance of physical properties such as film curability, elongation and hardness, the total amount of the cross-linking agent to the main polyurethane resin is solid. The fraction is preferably 5% by mass or more and 50% by mass or less.

  Further, as described above, silicon oxide or a phosphoric acid compound can be added to the polyurethane resin film of the present invention in order to further improve film properties such as corrosion resistance.

  Examples of silicon oxide include silicon dioxide. The silicon oxide may be a compound that is stably dispersed in water and does not cause sedimentation. Particularly, when colloidal silica is used, the effect of improving the solvent resistance and corrosion resistance is remarkably exhibited. For example, commercially available colloidal silica particles such as “Snowtex O”, “Snowtex OS”, “Snowtex OXS”, “Snowtex N”, “Snowtex NS”, “Snowtex NXS” (all manufactured by Nissan Chemical Industries, Ltd.), Fibrous colloidal silica such as “Snowtex UP” and “Snowtex PS” (manufactured by Nissan Chemical Industries, Ltd.) can be used depending on the pH of the treatment liquid (paint).

  The silicon oxide content is preferably 2% by mass to 20% by mass with respect to the solid content of the film. If it is less than 2% by mass, the effect is poor, and if it exceeds 20% by mass, the effect is saturated and uneconomical, and the workability and corrosion resistance may decrease. In addition, when a coated metal plate is produced by mixing a polyurethane resin containing silanol groups and silicon oxide together in a treatment bath, the total amount of siloxane bonds or Si-O bonds and silicon oxide is the amount of coating on the coated metal plate. The silicon content is preferably 2.1% by mass or more and 30% by mass or less with respect to the total solid content.

  Examples of the phosphoric acid compound include triammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium phosphate, potassium dihydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, diphosphate phosphate. Examples thereof include sodium hydrogen, calcium dihydrogen phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate and the like. Among them, triammonium phosphate, diammonium hydrogen phosphate, ammonium phosphate compound of ammonium dihydrogen phosphate, sodium phosphate, disodium hydrogen phosphate, sodium phosphate compound of sodium dihydrogen phosphate, phosphorus When using at least one compound among calcium phosphate compounds such as calcium dihydrogen phosphate and magnesium phosphate compounds such as magnesium hydrogen phosphate and magnesium dihydrogen phosphate, the effect of improving solvent resistance and corrosion resistance is remarkable. This is preferable. These phosphate compounds can be used depending on the pH of the treatment bath as long as they are water-soluble or soluble in acid or alkali, and either pure compounds or hydrates can be used. .

  The content of the phosphoric acid compound is preferably 0.1% by mass to 10% by mass with respect to the solid content of the film. If it is less than 0.1% by mass, the effect of improving the solvent resistance and corrosion resistance is poor, and if it exceeds 10% by mass, the hydration property to the film increases and the corrosion resistance may decrease.

  Furthermore, by appropriately adding a lubricity-imparting agent, a product with a low coefficient of friction can be obtained while maintaining good performance, a surface-treated metal material with excellent workability can be obtained, and the contact angle can be increased. . Typical examples of the lubricity-imparting agent include water-dispersible polyethylene resin, tetrafluoroethylene resin, stearic acid compound, natural paraffin wax, and the like. Among these, when a polyethylene resin or a tetrafluoroethylene resin is used, the effect of reducing lubricity and the effect of improving the contact angle remarkably appear, which is preferable.

  The lubricity imparting agent is preferably 0.2 to 30% by mass or less in terms of solid content of the treatment film. If the amount is less than 0.2% by mass, the effect is poor, and if it exceeds 30% by mass, the effect of reducing the friction coefficient is saturated, the film forming ability is lowered, and the corrosion resistance may be lowered.

  As metal materials applied to the present invention, Al killed steel plates, ultra-low carbon steel plates to which Ti, Nb, etc. are added, high strength steel plates to which reinforcing elements such as P, Si, Mn, etc. are added, Cr-containing steels, etc. , Various metal materials can be applied. In addition, Al-based alloy materials, Ti-based materials, and Cu-based materials are considered not necessary as anti-rust treatment, but they can be applied for purposes such as design coating, scratch prevention, and fingerprint adhesion prevention. is there.

  As a coating layer of metal material, it exhibits excellent film characteristics when applied with Zn plating or Zn-based alloy plating such as Zn-Ni, Zn-Fe, Zn-Mg, Zn-Al-Mg-Si, etc. Alternatives are possible. Also, Al or an alloy composed of Al and at least one of Si, Zn, and Mg, for example, Al-based plating such as Al-Si based alloy, Al-Zn based alloy, Al-Si-Mg alloy, or Sn and Zn. It can also be applied to alloy plating. In the present invention, the film thickness of the treatment film is not particularly limited, but is preferably 0.1 μm or more and 5 μm or less for normal use. If it is less than 0.1 μm, the film is too thin, and there is a possibility that rust prevention and other functions are hardly exhibited. On the other hand, a film thickness of 5 μm or more may cause various problems such as deterioration in appearance and generation of residue due to discoloration during processing such as press molding.

  Among them, the effect is most remarkable when the coating composition of the present invention is applied to a Zn-plated steel sheet or a Zn-based alloy-plated steel sheet. The effect is that the white rust generation area ratio after 240 hours of the salt spray test specified in JIS-Z-2371 is 5% or less. More preferably, the white rust occurrence rate is 1% or less. There is a concern about the long-term corrosion resistance of the coated metal plate composition exceeding 5%.

  In addition, when the salt spray test specified in JIS-Z-2371 is performed after the strong alkaline degreasing in which the coated metal material is a zinc-based plated steel sheet and the pH of the degreasing liquid is 11 to 12, the white after 120 hours is obtained. The rust generation area ratio is preferably 5% or less. More preferably, the white rust occurrence rate is 1% or less. There is a concern about the long-term corrosion resistance after the alkaline degreasing process in the coated metal plate configuration in which the white rust occurrence rate exceeds 5%.

  The treatment liquid (paint) can be applied by a known method such as spraying, roll coating, bar coating, dipping or electrostatic coating. Baking and drying may be performed by a known method using a hot air drying furnace, an induction heating furnace, a near infrared furnace, a direct-fired furnace, or a combination of these. Depending on the type of resin used, it can be cured by energy rays such as ultraviolet rays and electron beams. Moreover, the cooling after heat drying is possible by well-known methods, such as water cooling and air cooling, or those combinations.

  The heating temperature is preferably 80 ° C. to 250 ° C. at the ultimate plate temperature. Below 80 ° C., drying for a long time is necessary for sufficient crosslinking, which is not practical. If the temperature exceeds 250 ° C., the organic resin is thermally decomposed, which adversely affects the corrosion resistance. Industrially, 100 to 200 ° C. is more preferable.

  Furthermore, it is possible to obtain a urethane-based resin film having a contact angle increased and a film performance further improved by forming a film by the following manufacturing method. That is, assuming that the ultimate temperature of the metal material during baking (hereinafter referred to as “the ultimate plate temperature”) is PMT and the glass transition point of the resin film is Tg, the baking conditions satisfy the relationship of PMT−Tg ≧ 10 ° C. Good corrosion resistance can be obtained by manufacturing. This parameter represents the effect of the arrival plate temperature on the corrosion resistance due to the glass transition temperature. The condition of PMT-Tg <10 ° C. is not preferable because the variation in corrosion resistance becomes large. In addition, when the time required to reach the ultimate plate temperature during baking is t, good corrosion resistance can be obtained by manufacturing under baking conditions where the relationship of t × log (PMT / Tg) ≧ 0.5 is established. . This parameter represents the effect of the ratio of the reached plate temperature to the glass transition temperature multiplied by the baking time on the corrosion resistance. The condition of t × log (PMT / Tg) <0.5 is not preferable because the heating time for PMT and Tg is short and the variation in corrosion resistance becomes large.

  The present invention is intended for a coated metal plate that satisfies the performance by one-step treatment. If the cost is not taken into consideration, the chemical conversion treatment film such as a phosphate treatment film is applied before the treatment film is applied. It is also possible to further improve the corrosion resistance and provide functions as required by adding the above, or by the two-stage treatment of the same chromate-free coating, and further by the multilayer treatment. In addition, as post-plating treatment, before chemical conversion treatment, there are zero spangle treatment, which is uniform appearance after hot dipping, annealing treatment, which is modification treatment of the plating layer, surface condition, temper rolling for material adjustment, etc. However, in the present invention, these are not particularly limited and can be applied.

  Hereinafter, the present invention will be described in more detail by way of examples.

Example 1
The following resins were used as water-based urethane resins used for metal surface treatment agents. These were mixed with various resins and additives to obtain a predetermined metal surface treatment agent. The contents are shown in Table 1.

  <Polyurethane resin A>: A water-dispersible polyurethane emulsion containing a carboxyl group and neutralized with triethylamine, the contact angle of the resin single film at 20 ° C. is 70 degrees, and the Tg of the single film is 135 ° C. and 20 ° C. Polyurethane resin whose film has an elastic modulus of 5.0 GPa.

  <Polyurethane resin B>: A water-dispersible polyurethane emulsion containing carboxyl groups and neutralized with dimethylethanolamine, containing 1.0% by mass of silanol groups in the resin, and having a single resin film at 20 ° C. A polyurethane resin having a contact angle of 71 °, a Tg of a single film of 138 ° C., and an elastic modulus of the film at 20 ° C. of 5.1 GPa.

  <Polyurethane resin C>: A water-dispersible polyurethane emulsion containing carboxyl groups and neutralized with triethylamine, containing 0.5% by mass of silanol groups in the resin, and contacting the resin alone film at 20 ° C. A polyurethane resin having an angle of 75 degrees and a single coating Tg of 110 ° C. and a coating elastic modulus of 3.3 GPa at 20 ° C.

  <Polyurethane resin D>: A water-dispersible polyurethane emulsion containing a carboxyl group and neutralized with ammonia, containing 1.5% by mass of silanol groups in the resin, and contacting a resin single film at 20 ° C. A polyurethane resin having an angle of 68 degrees and a single coating having a Tg of 65 ° C. and an elastic modulus of the coating at 20 ° C. of 0.6 GPa.

  <Polyurethane resin E>: A water-dispersible polyurethane emulsion containing a carboxyl group and neutralized with triethylamine, the contact angle of the resin single film at 20 ° C. is 55 degrees, and the Tg of the single film is 40 ° C. and 20 ° C. Polyurethane resin whose film has an elastic modulus of 0.3 GPa.

The contents of the mixed resin, colloidal silica, and crosslinking agent in the treating agent shown in Table 1 are as follows.
Epoxy resin: Bisphenol-type aqueous epoxy resin emulsion Acrylic resin: Carboxyl group, hydroxyl group-containing aqueous acrylic resin emulsion Colloidal silica: Snowtex N (manufactured by Nissan Chemical Industries)
Crosslinking agent F: Carbodiimide compound; Carbodilite E-03A (Nisshinbo Co., Ltd.)
Crosslinking agent G: Organic titanate compound; Olgatics TC-400 (manufactured by Matsumoto Pharmaceutical Co., Ltd.)

The following metal materials were used as processing substrates.
H: Electrogalvanized steel sheet: Plate thickness 0.8 mm, plating adhesion 20 g / m ²
J: Electro-zinc-Ni alloy-plated steel sheet: Plate thickness 0.8 mm, plating adhesion 20 g / m ²
K: hot dip galvanized steel sheet: plate thickness 0.8 mm, plating adhesion 50 g / m ²
M: hot dip zinc-iron alloy plated steel plate: plate thickness 0.8 mm, plating adhesion 45 g / m ²
N: Stainless steel sheet: 0.5 mm thick, ferritic stainless steel sheet Steel component: C; 0.008 mass%, Si: 0.07 mass%, Mn: 0.15 mass%, P: 0.011 mass%,
S; 0.009 mass%, Al; 0.067 mass%, Cr; 17.3 mass%, Mo; 1.51 mass%,
N: 0.0051 mass%, Ti: 0.22 mass%, balance Fe and inevitable impurities

  The plated steel sheet was subjected to alkaline degreasing immediately before use, washed with water and dried, coated with the treatment liquid shown in Table 1 by bar coating, and dried in a hot air drying furnace to obtain a test material. The furnace temperature of the hot air drying furnace was 350 ° C., the temperature reached during drying was 150 ° C. as the ultimate plate temperature (PMT), and the time reached was 15 seconds. Details of the test materials are shown in Table 2. The contact angle of the finished painted metal plate was measured at a temperature of 20 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.).

  The following evaluation was performed on the coated metal plate produced as described above.

(1) Coating film adhesion The coated plate is put into a 1mm grid on the coating surface with a cutter knife, extruded 7mm with an Erichsen tester so that the coating surface becomes convex, and then a tape peeling test is performed. It was. About the method of putting a grid, the extrusion method of Erichsen, and the method of tape peeling, it implemented according to the method of JIS-K5400.88.2 and JIS-K5400.88.5. Evaluation after tape peeling was performed by a 10-point full scale evaluation according to an example diagram of evaluation described in JIS-K5400.88.5.

(2) Solvent resistance The coated board was rubbed with methyl ethyl ketone. The gauze was fixed to the tip of a 15 mmφ silicon rubber cylinder, 5 mL of the solvent was contained, and the slide was slid 10 times under the condition of a load of 4.9 N / cm ² and the appearance was observed. Further, the test piece was subjected to a salt spray test (SST) defined in JIS-Z2371, and the appearance after 48 hours was observed. The evaluation criteria are shown below.
5: No white rust
4: White rust generation less than 1%
3: White rust generated 1% or more and less than 5%
2: White rust generation 5% or more and less than 20%
1: White rust generation 20% or more

(3) Corrosion resistance (a) A flat plate test piece whose end face / back face is sealed is subjected to a salt spray test (hereinafter referred to as SST) specified in JIS-Z2371, and evaluated by the occurrence rate of white rust after 240 hours. did. Corrosion resistance evaluation criteria are shown below.
5: No white rust
4: White rust generation less than 1%
3: White rust generated 1% or more and less than 5%
2: White rust generation 5% or more and less than 20%
1: White rust generation 20% or more (b) End face of flat test piece after alkali degreasing treatment for 2 minutes in FC-4460 (manufactured by Nihon Parkerizing) 2% degreasing solution at 60 ° C, water washing and drying -The back side was sealed and SST was performed. The corrosion resistance was evaluated by the white rust occurrence rate after 120 hours. Corrosion resistance evaluation criteria are shown below.
5: No white rust
4: White rust generation less than 1%
3: White rust generated 1% or more and less than 5%
2: White rust generation 5% or more and less than 20%
1: White rust generation 20% or more

(4) Workability After applying Z3 (made by Idemitsu Kosan Co., Ltd.) as a rust preventive oil to the flat plate test piece, a square tube deep drawing was performed, and the appearance after the test was observed and evaluated. Square tube deep drawing was performed under the conditions of a blank diameter of 100 mm, a rectangular tube punch width of 50 mm, a shoulder R of 5 mm, and a wrinkle holding pressure of 9.8 kN.
5: No change
4: Slight film discoloration
3: The film is discolored or slightly processed.
2: Processing scratches or slight residue
1: Large processing scratches or large film peeling

  No. In 15, 16, and 17, urethane resin was used, but it was found that long-term corrosion resistance was poor because of low contact angle and high hydrophilicity.

No. By using the film configurations of 2 to 14 examples of the present invention, good corrosion resistance, film adhesion, solvent resistance, and workability were obtained. No. Nos. 2 to 4, 6 to 9, 11 to 14 having a glass transition point and a high elastic modulus. No. 2-14 containing silanol groups Those using 4, 5, 11 to 14 cross-linking agents tend to have a large contact angle and have particularly good performance.

(Example 2)
Using the polyurethane resin B and polyurethane resin C described in Example 1, the surface treating agents shown in Table 4 were prepared. After applying a predetermined amount of these treatment agents to the electrogalvanized steel sheet of the metal material H described in Example 1 by roll coating so that the dry film thickness becomes 1.0 μm, the temperature of the hot air drying oven, the baking time ( It was produced by changing t) and varying the ultimate plate temperature (PMT). The contact angle of the thus produced sample was measured by the same method as in Example 1. In addition, in the same manner as (3) corrosion resistance described in Example 1, a salt spray test after flat plate and alkaline degreasing was carried out, and in order to clarify a more preferable range, white rust generation rate (area%) evaluated. The results are shown in Table 5.

  It was found that the contact angle can be increased as the PMT is increased or the heating time is increased.

  FIG. 1 shows the relationship between PMT-Tg and the white rust occurrence rate, and FIG. 2 shows the relationship between t × log (PMT / Tg) and the white rust occurrence rate. As a result, a product produced by baking and curing under the condition of PMT-Tg ≧ 10 ° C. has a white rust occurrence rate of 1% or less, and exhibits particularly good corrosion resistance. Furthermore, it was found that the occurrence rate of white rust was 1% or less under the condition of t × log (PMT / Tg) ≧ 0.5, and particularly good corrosion resistance was exhibited.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a coated metal material that does not contain hexavalent chromium having high environmental impact, has extremely high corrosion resistance, and has good workability, and a method for manufacturing the same.

It is a graph which shows the relationship between PMT-Tg and white rust incidence (it represents the influence which the magnitude | size of the ultimate plate temperature with respect to a glass transition temperature has on corrosion resistance). FIG. 5 is a graph showing the relationship between t × log (PMT / Tg) and the white rust occurrence rate (representing the effect of the ratio of the reached plate temperature to the glass transition temperature multiplied by the baking time on the corrosion resistance).

Explanation of symbols

PMT: Ultimate plate temperature (° C)
Tg: Glass transition temperature of resin film (° C)
t: Baking time to reach the ultimate plate temperature (s)

Claims (9)

The metal material surface, have a silanol group in the resin skeleton, the elastic modulus at 20 ° C. of single coating of 100 ° C. or higher, or the resin glass transition temperature is water dispersible or water soluble at least 0.5GPa polyurethane A first step of applying a paint containing at least a resin;
The relationship between the glass transition temperature Tg (° C.) of the polyurethane resin and the ultimate temperature PMT (° C.) of the metal material during baking satisfies PMT−Tg ≧ 10 (° C.), and the glass transition of the polyurethane resin. Baking and hardening is performed under the condition that the relationship between the temperature Tg (° C.), the baking reached material temperature PMT (° C.), and the baking time t (seconds) satisfies t × log (PMT / Tg) ≧ 0.5. Process and;
Only including,
The method for producing a coated metal material, wherein the paint contains a phosphoric acid compound . The polyurethane resin contains a carboxyl group or a sulfonic acid group;
The method for producing a coated metal material according to claim 1, wherein the resin is a resin neutralized with a neutralizer and dispersed or dissolved in water.   The method for producing a coated metal material according to claim 1, wherein the paint contains silicon oxide.   The method for producing a coated metal material according to claim 3, wherein the silicon oxide content is 2% by mass or more and 20% by mass or less as a silicon amount with respect to the total solid content of the paint. 2. The method for producing a coated metal material according to claim 1 , wherein the content of the phosphoric acid compound is 0.1% by mass or more and 10% by mass or less as a phosphorus amount with respect to the total solid content of the paint. The paint, as the urethane resin of the crosslinking agent, a water-soluble isocyanate, carbodiimide group-containing compounds, oxazoline group-containing compound, characterized in that it contains at least one member selected from the group consisting of organic titanates, claim 1 or 3 method for manufacturing a coated metal material according to. The method for producing a coated metal material according to claim 1, 3 or 6 , wherein the paint further contains a lubricity imparting agent. The method for producing a coated metal material according to claim 7 , wherein the content of the lubricity-imparting agent is 0.2 to 30% by mass with respect to the total solid content of the paint. The method for producing a coated metal material according to claim 1, wherein the metal material is a zinc-based plated steel sheet.

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