JP2007277377A - Aqueous coating composition for surface treatment of metallic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous coating composition for the surface treatment of a metallic material, excellent in corrosion resistance, chemical resistance, and adhesion. <P>SOLUTION: In preparing an aqueous coating composition for the surface treatment of a metallic material, containing an aqueous polyurethane resin and a hydrophobic compound, the hydrophobic compound is added to the aqueous polyurethane resin and, together with the aqueous polyurethane resin, is dispersed in water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water-based coating composition for metal materials, and more particularly to a water-based coating composition for surface treatment of metal materials that uses a water-dispersible resin composition and is excellent in corrosion resistance, chemical resistance, and adhesion.

  Conventionally, water-based paints have been used as surface treatment agents for metal materials such as steel sheets used for home appliances, building materials, and automobiles from the viewpoints of environmental pollution, occupational health, and safety. As these resin components, epoxy resins, acrylic resins, polyester resins, polyurethane resins and the like are used.

  Examples of the prior art include an aqueous dispersion composition obtained by reacting an ethylene-unsaturated carboxylic acid copolymer and an epoxy compound (Patent Document 1), a vinyl copolymer having a hydrolyzable silyl group and an amineimide group. A water-based anticorrosive coating composition comprising a coalesced, uncured epoxy resin and antirust pigment (Patent Document 2), a modifier component containing at least one of a diketone compound, a ketoester compound, a ketimine compound, and a benzotriazole compound, a bisphenol type Examples thereof include an aqueous resin composition using an epoxy resin and a phosphoric acid compound (Patent Document 3), a water-dispersed urethane composition containing a dicarboxylic acid dihydrazide compound (Patent Document 4), and the like. Among these, those containing a polyurethane resin are particularly useful because they have a good balance of physical properties such as strength and elongation of the coating film and good adhesion.

However, even if the water-dispersible resin composition containing the polyurethane resin is used, the actual situation is that various performances such as corrosion resistance, chemical resistance and adhesion have not been sufficiently satisfied.
JP 2002-241670 A Japanese Patent No. 2515207 JP 2003-2950 A JP 2003-226728 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a water-based coating composition for metal material surface treatment that is excellent in corrosion resistance, chemical resistance and adhesion.

  In order to solve the above problems, the present invention provides a water-based coating composition for surface treatment of a metal material containing a water-dispersible resin and a hydrophobic component, wherein the hydrophobic component is added to the water-dispersible resin. Then, it is dispersed in water together with the water dispersible resin.

  With this configuration, a water-based coating composition for a metal material surface treatment agent in which a water-dispersible resin and a hydrophobic component are uniformly dispersed in water is obtained, and the corrosion resistance, chemical resistance, and adhesion are improved.

  Here, the water-dispersible resin is preferably an aqueous polyurethane resin, and the compound having two or more active hydrogen atoms, which is a raw material of the aqueous polyurethane resin, is an oxyalkylene adduct of bisphenol A, an olefinic polyol. More preferably, it contains at least one active hydrogen-containing compound selected from vegetable oil-based polyols.

  The hydrophobic component preferably contains at least one hydrophobic compound selected from mineral oil compounds, sulfonate compounds, natural waxes and synthetic waxes.

  The water-based paint composition for surface treatment of a metal material of the present invention exhibits extremely excellent performance in corrosion resistance, chemical resistance and adhesion because a water-dispersible resin and a hydrophobic component are uniformly dispersed in water. To do.

  As described above, the water-based coating composition for a metal material surface treatment agent of the present invention contains a water-dispersible resin and a hydrophobic component, and after adding the hydrophobic component to the water-dispersible resin, It is dispersed.

  Examples of the water dispersible resin in the present invention include vinyl acetate resin, ethylene vinyl acetate resin, alkyd resin, acrylic resin, styrene resin, polyamide resin, polyester resin, polyethylene resin, polyurethane resin, and the like. It is done. These resins may be used alone or in combination of two or more. Among these water-dispersible resins, a polyurethane-based resin that forms a tough and flexible film is particularly preferable.

  Examples of the hydrophobic compound contained in the hydrophobic component in the present invention include mineral oil compounds, sulfonate compounds, natural or synthetic waxes, silicon compounds, and fluorine compounds. These hydrophobic compounds may be used alone or in combination of two or more. For example, mineral oil-based compounds are mineral oils, sulfonate-based compounds are petroleum sulfonates, synthetic sulfonates, natural waxes are vegetable waxes, animal waxes, mineral waxes, petroleum waxes, and synthetic waxes are synthetic hydrocarbon waxes. , Modified wax, oil-based wax, and the like. Of these, mineral oil compounds and sulfonate compounds are particularly preferred.

  The mixing ratio of the water-dispersible resin and the hydrophobic component is preferably 100 / 0.5 to 100/50, more preferably 100/1 to 100/20, in terms of solid content weight ratio. When the solid content weight ratio is less than 100 / 0.5, the effect of blending the hydrophobic component is not sufficiently exhibited. Moreover, when solid content weight ratio exceeds 100/50, chemical resistance and adhesiveness will become inadequate.

  The water-based paint composition for surface treatment of a metal material according to the present invention is obtained by adding a hydrophobic component to an NCO group-containing urethane prepolymer obtained by a reaction between two or more active hydrogen atom-containing compounds and an organic polyisocyanate, and emulsifying in water. Thereafter, it is obtained by increasing the molecular weight by reaction with a polyvalent amine compound or water. Alternatively, it can be obtained by adding a hydrophobic component to an OH group-terminated urethane polymer obtained by a reaction between two or more active hydrogen atom-containing compounds and an organic polyisocyanate, and emulsifying it in water.

Preparation and emulsification method of NCO group-containing urethane prepolymer The NCO group-containing urethane prepolymer can be prepared and emulsified as follows.

  1) An NCO group-containing urethane prepolymer synthesized from a compound having an active hydrogen atom and a salt-forming group having reactivity with an NCO group, two or more active hydrogen atom-containing compounds, and an organic polyisocyanate; An anionic or cationic aqueous polyurethane resin is obtained by adding a forming agent and a hydrophobic component, emulsifying in water, and then chain-extending with a polyamine compound or water.

  2) Hydrophobic NCO group-containing urethane prepolymer synthesized from ethylene oxide alone or monoalcohol or polyhydric alcohol with addition of ethylene oxide and propylene oxide, two or more active hydrogen atom-containing compounds, and organic polyisocyanate A nonionic water-based polyurethane resin is obtained by adding a functional component and emulsifying in water, and then chain-extending with a polyvalent amine compound or water.

  3) To an NCO group-containing urethane prepolymer synthesized from two or more active hydrogen atom-containing compounds and an organic polyisocyanate, an anion, cation, nonionic surfactant and a hydrophobic component are added, and After emulsification, an aqueous polyurethane resin is obtained by chain elongation with a polyvalent amine compound or water.

  4) An NCO group-containing urethane prepolymer synthesized from a compound having an active hydrogen atom and a salt-forming group having reactivity with an NCO group, two or more active hydrogen atom-containing compounds, and an organic polyisocyanate; An anionic or cationic aqueous system by adding a forming agent, a surfactant such as anion, cation, nonionicity, and a hydrophobic component, emulsifying in water, and then chain-extending with a polyamine compound or water A polyurethane resin is obtained.

Preparation and emulsification method of OH group-terminated urethane polymer The above-mentioned OH group-terminated urethane polymer can be prepared and emulsified as follows.

  1) To an OH group-terminated urethane polymer synthesized from a compound having an active hydrogen atom reactive with an NCO group and a salt-forming group, two or more active hydrogen atom-containing compounds, and an organic polyisocyanate. An anionic or cationic aqueous polyurethane resin can be obtained by adding a forming agent and a hydrophobic component and emulsifying in water.

  2) Hydrophobic OH group-terminated urethane polymer synthesized from ethylene oxide alone or monoalcohol or polyhydric alcohol with addition of ethylene oxide and propylene oxide, two or more active hydrogen atom-containing compounds, and organic polyisocyanate. A nonionic water-based polyurethane resin is obtained by adding a water-soluble component and emulsifying it in water.

  3) To an OH group-terminated urethane polymer synthesized from two or more active hydrogen atom-containing compounds and an organic polyisocyanate, an anion, cation, nonionic surfactant and a hydrophobic component are added, A water-based polyurethane resin is obtained by emulsifying.

  4) Salt formation on an OH group-terminated urethane polymer synthesized from a compound having an active hydrogen atom reactive with an NCO group and a salt-forming group, two or more active hydrogen atom-containing compounds, and an organic polyisocyanate An anionic or cationic aqueous polyurethane resin is obtained by adding an agent, a surfactant such as an anion, a cation, or a nonionic agent, and a hydrophobic component and emulsifying it in water.

  As the compound having two or more active hydrogen atoms in the present invention, those known in the field of urethane industry can be used. Specifically, two or more hydroxyl groups are present at the molecular end or in the molecule. Examples thereof include those having an amino group or a mercapto group, and generally known polyethers, polyesters, polyether esters, polycarbonates, polythioethers, polyacetals, polyolefins, polysiloxanes, fluorine-based and vegetable oil-based ones. Among these, preferred are compounds having two or more hydroxyl groups at the molecular ends. In addition, it is preferable that the molecular weight of the compound which has 2 or more of active hydrogen groups in a molecule terminal is the range of 62-5,000. This is because there is no active hydrogen group-containing compound having a molecular weight of less than 62, and when the molecular weight exceeds 5,000, the amount of urethane bonds decreases, making it difficult to form a tough and flexible film.

  Specifically, examples of the compound having a group having two or more active hydrogen atoms include ethylene glycol, propylene glycol, propanediol, butanediol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, Neopetyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether, trimethylolpropane, Derived from polyhydric alcohols such as serine and pentaerythritol, their oxyalkylene adducts, these polyhydric alcohols and oxyalkylene adducts, and polycarboxylic acids, polycarboxylic anhydrides, or polycarboxylic esters. Ester compounds, polycarbonate polyols, polycaprolactone polyols, polyester polyols, polythioether polyols, polyacetal polyols, polytetramethylene glycols, polybutadiene polyols, castor oil polyols, soybean oil polyols, fluorine polyols, silicone polyols, and other modified compounds thereof The body is mentioned. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and butylene oxide. These compounds having a group having two or more active hydrogen atoms may be used alone or in combination of two or more.

  In one embodiment, the compound having a group having two or more active hydrogen atoms contains at least one active hydrogen-containing compound selected from an alkylene oxide adduct of bisphenol A, an olefinic polyol, and a vegetable oil-based polyol. Is preferred. Examples of the polyolefin include polybutadiene polyol, polyisoprene polyol, hydrogenated polybutadiene polyol, hydrogenated polyisoprene polyol, and the like. Examples of vegetable oil-based polyols include modified soybean oil, castor oil, dehydrated castor oil, and hydrogenated castor oil. Examples of these are various hydroxyl group-containing vegetable oil derivatives. These active hydrogen-containing compounds are preferably in the range of 10 to 70% by weight in terms of solid content with respect to the aqueous polyurethane resin. If the content is less than 10% by weight, the alkali resistance and corrosion resistance are not sufficiently exhibited, and if it exceeds 70% by weight, the tough film-forming property of the urethane resin is inferior.

  The organic polyisocyanate compound in the present invention is well known in the field of urethane industry, and any compound can be used. Examples of organic polyisocyanate compounds include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) polymeric MDI, hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), isophorone diisocyanate (IPDI), Aromatic, aliphatic and alicyclic isocyanates such as hydrogenated MDI (H12MDI), lysine diisocyanate, naphthalene diisocyanate, norbornaphthalene diisocyanate, burette hexamethylene diisocyanate, isocyanurated hexamethylene diisocyanate alone Or it can be mixed and used.

  When the urethane prepolymer having an NCO group is emulsified and dispersed in the water-based polyurethane resin of the present invention, the molecular weight is increased by reaction with a polyvalent amine compound or water. Aliphatic polyamine compounds such as methylenediamine, propylenediamine, diethylenetriamine and triethylenetetramine, aromatic polyamine compounds such as metaxylenediamine, tolylenediamine and diaminodiphenylmethane, alicyclic polyamine compounds such as piperazine and isophoronediamine, hydrazine, adipine And polyhydrazide compounds such as acid dihydrazide. These polyamine compounds may be used alone or in combination of two or more. Moreover, you may use reaction terminators, such as monovalent amines, such as a dibutylamine, and methyl ethyl ketoxime, as a reaction terminator to such an extent that polymerization is not inhibited greatly.

  The water-based paint composition for surface treatment of a metal material of the present invention contains the water-based polyurethane resin and a hydrophobic component, and the composition of the present invention has properties suitable for the purpose when the water-based resin composition is prepared. In order to reduce the performance of the composition of the present invention, various additives such as thickeners, curing catalysts, leveling agents, antifoaming agents, film-forming aids, and other types of water-dispersible resins It is also possible to mix within the range.

  The compound having an active hydrogen atom and a salt-forming group having reactivity with the NCO group used in the present invention and the corresponding salt-forming agent include 1) a compound having a salt-forming carboxylic acid or sulfonic acid group, and Corresponding salt-forming agents, 2) compounds having groups that can be quaternary or tertiary groups neutralizable with acids and the corresponding salt-forming agents can be used.

  Examples of the compound having a salt-forming carboxylic acid or sulfonic acid group in 1) above include hydroxy acids such as glycolic acid, malic acid, glycine, aminobenzoic acid, alanine, dimethylolpropionic acid, dimethylolbutanoic acid, amino Examples include carboxylic acids, polyvalent hydroxy acids, aminoethyl sulfonic acids, aminosulfonic acids such as 2-hydroxyethanesulfonic acid, and hydroxysulfonic acids. Examples of the corresponding salt forming agent include monovalent metal hydroxides such as potassium hydroxide, sodium hydroxide and calcium hydroxide, and tertiary amine compounds such as ammonia, trimethylamine and triethylamine.

  Examples of the compound having a group capable of becoming a quaternary or tertiary group that can be neutralized with the acid of 2) above include N, such as N, N-dimethylethanolamine, N-methyldiethanolamine, and N-ethyldiethanolamine. -N-alkyldiaminoalkylamines such as alkyl dialkanolamine, N-methyldiaminoethylamine, N-ethyldiaminoethylamine and the like. These compounds may be used alone or in combination of two or more.

  In addition, as salt forming agents corresponding thereto, for example, organic acids such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, malonic acid, adipic acid, dimethyl sulfate, diethyl sulfate, methyl chloride, benzyl chloride, formic acid , Inorganic acids such as hydrochloric acid, phosphoric acid, nitric acid, and compounds having reactive halogen atoms.

  Examples of monoalcohols used in the present invention include monoalcohol or polyalcohol ethylene oxide alone, or monoalcohols in ethylene oxide and propylene oxide adducts such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, lauryl alcohol, etc. However, examples of the polyhydric alcohol include the polyhydric alcohols.

  As the surfactant for emulsification such as anion, cation, nonion and amphoteric used in the production of the polyurethane water dispersion of the present invention, all those usually used in the field of surfactants may be used alone or in combination. .

The crosslink density of the aqueous polyurethane resin used in the present invention is preferably 0.01 to 0.50 per 1000 molecular weight of the aqueous polyurethane resin. The crosslinking density here can be determined by calculating according to the following equation (1). That is, the active hydrogen atom-containing compound (A) having the molecular weight MW _A1 and the functional group number F _A1 is WA ₁ g, the active hydrogen atom-containing compound (A) having the molecular weight MW _A2 and the functional group number F _A2 is WA ₂ g, and the molecular weight MW. active hydrogen atom-containing compound _AJ and functional groups F _AJ (a) and W _Aj g (j is an integer of 1 or more), the molecular weight MW _B1, an organic polyisocyanate functional groups _{F B1 (B) W B1 g} , the organic polyisocyanate of molecular weight MW _B2 and functional groups F _B2 (B) and W _B2 g, and the organic polyisocyanate of molecular weight MW _Bk and functional groups _{F Bk (B) W Bk g} (k is an integer of 1 or more), the molecular weight MW _C1, polyvalent amine compound of functional groups F _C1 (C) and the W _C1 g, molecular weight MW _Cm, polyvalent amine compound of functional groups F _Cm the (C) W _Cm g (m is an integer of 1 or more) Solid content in water-based polyurethane resin obtained by reacting with Crosslink density per 1000 molecular weight can be determined by calculation by Equation 1 below.

  If the crosslinking density is 0.01 or less, the degree of crosslinking is low, resulting in poor water resistance and poor alkali resistance and corrosion resistance. If it exceeds 0.50, the resin becomes brittle, and adhesion and flex resistance are poor. .

  In the present invention, the glass transition temperature of the resin solid content contained in the water-based polyurethane resin is preferably in the range of 20 to 130 ° C. If the temperature is lower than 20 ° C., the cohesive strength of the resin is low, so that the water resistance, alkali resistance, corrosion resistance, and wear resistance are inferior. If the temperature exceeds 120 ° C., the resin becomes brittle and the flex resistance is poor. Moreover, if it is outside the range of 20 to 130 ° C., the workability at the time of processing will be poor.

  Metal materials suitable for using the water-based paint composition for surface treatment of metal materials of the present invention include cold rolling, hot rolled steel sheets, carbon steel sheets, steel sheets such as silicon steel sheets, electrogalvanizing, hot dip galvanizing, 55% aluminum zinc plating, 5% aluminum zinc plating, aluminum plating, iron zinc plating, nickel plating, copper plating, tin plating, zinc nickel plating, zinc magnesium plating, etc., various steel plates, stainless steel plate, copper plate, pure aluminum material, Examples thereof include a metal material mainly composed of aluminum or an aluminum alloy such as an aluminum alloy material.

  In order to improve corrosion resistance and adhesion, the metal material surface may be subjected to chromate treatment or phosphate treatment.

  Various known additives may be added to the water-based coating composition for surface treatment of a metal material of the present invention as necessary. Examples of such additives include a rust inhibitor, a rust preventive pigment, a dye, a film forming aid, an inorganic crosslinking agent, an organic crosslinking agent, a silane coupling agent, an antiblocking agent, a viscosity modifier, a leveling agent, and an antifoaming agent. Agents, dispersion stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents and the like.

  The water-based paint composition for surface treatment of a metal material of the present invention includes a phosphoric acid compound, a chromic compound, a vanadium compound, a molybdate compound, a zirconium compound, a titanium compound, a cerium compound, a manganese compound, and tungsten. You may mix | blend antirust agents, such as an acid type compound, a boric acid type compound, a nitric acid type compound, hydrofluoric acid, and colloidal silica.

  The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

  The polyurethane water dispersion of each Example and each comparative example was prepared in the following procedure. While calculating the crosslinking density of each dispersion, the glass transition temperature was measured, and the results are summarized in Table 1.

Example 1
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 200 parts by weight of polytetramethylene ether glycol (Poly THF-1000, manufactured by BASF, number of active hydrogen atoms 2) and 1,4 -20 parts by weight of cyclohexanedimethanol (2 active hydrogen atoms), 6 parts by weight of trimethylolpropane (3 active hydrogen atoms), 15 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), and isophorone diisocyanate 133 Part by weight and 243 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 1.7% by weight based on the nonvolatile content. The solution was cooled to 45 ° C., 26 parts by weight of a mineral oil-based compound (trade name: Rasmin KP-700, manufactured by Kyoeisha Chemical Co., Ltd.) was added, neutralized by adding 11.3 parts by weight of triethylamine, and then a homogenizer was used. Then, 962 parts by weight of water was gradually added and emulsified and dispersed. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30% by weight.

(Example 2)
A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube was charged with 200 parts by weight of a polyester polyol (manufactured by Hitachi Chemical Co., Ltd., 2 active hydrogen atoms) and 1,6-hexanediol ( Active hydrogen number 2) 20 parts by weight, trimethylolpropane (active hydrogen atom number 3) 3 parts by weight, N-methyldiethanolamine (active hydrogen atom number 2) 25 parts by weight, isophorone diisocyanate 130 parts by weight, methyl ethyl ketone 190 Part by weight was added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of urethane prepolymer having a free isocyanate group content of 1.2% by weight based on the nonvolatile content. The solution was cooled to 45 ° C. and quaternized by adding 26.5 parts by weight of dimethyl sulfate. Next, 19.0 parts by weight of a mineral oil-based compound (trade name: Rasmin KP-700, manufactured by Kyoeisha Chemical Co., Ltd.) was added, and 1134 parts by weight of water was gradually added and emulsified and dispersed while using a homogenizer. This was decompressed, and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 25%.

(Example 3)
A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube was charged with 200 parts by weight of a polyester polyol (Teslac 2477, manufactured by Hitachi Chemical, 2 active hydrogen atoms) and trimethylolpropane (active hydrogen). 3) 4 parts by weight of atoms, 12 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), 80 parts by weight of dicyclohexylmethane diisocyanate and 207 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours, A methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 1.5% by weight with respect to 5 minutes was obtained. The solution was cooled to 45 ° C., 15 parts by weight of a petroleum sulfonate compound (trade name: Sulhol Ba-30N, manufactured by Matsumura Petroleum) was added, neutralized by adding 9.1 parts by weight of triethylamine, and then a homogenizer was used. While adding 761 parts by weight of water, the mixture was emulsified and dispersed. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30%.

Example 4
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 80.8 parts by weight of polyester polyol (Nipporan 4009, manufactured by Nippon Polyurethane Industry, 2 active hydrogen atoms) and bisphenol A propylene oxide 162 parts by weight of an adduct (polyether BPX-11, manufactured by Asahi Denka Kogyo, 2 active hydrogen atoms), 6.8 parts by weight of trimethylolpropane (3 active hydrogen atoms), dimethylolpropionic acid (active hydrogen atoms) Formula 2) 16.2 parts by weight, 135.8 parts by weight of hexamethylene diisocyanate, and 321 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours. The content of free isocyanate groups with respect to the nonvolatile content was 1.5. A methyl ethyl ketone solution of urethane prepolymer in weight% was obtained. The solution was cooled to 45 ° C., 20 parts by weight of a mineral oil compound (trade name: Rasmin KP-700, manufactured by Kyoeisha Chemical Co., Ltd.) was added, neutralized by adding 12 parts by weight of triethylamine, and then using a homogenizer. 1031 parts by weight of water was gradually added and emulsified and dispersed. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30%.

(Example 5)
200 parts by weight of ethylene oxide adduct of bisphenol A (New Pole BPE-40, manufactured by Sanyo Chemical Industries, 2 active hydrogen atoms) is added to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and nitrogen blowing tube. 75 parts by weight of trimethylolpropane (3 active hydrogen atoms), 15 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), 195 parts by weight of dicyclohexylmethane diisocyanate, and 291 parts by weight of methyl ethyl ketone. The reaction was carried out at 0 ° C. for 4 hours to obtain a methyl ethyl ketone solution of urethane prepolymer having a free isocyanate group content of 1.7% by weight based on the nonvolatile content. The solution was cooled to 45 ° C., 42 parts by weight of a combination of a mineral oil-based compound and a petroleum sulfonate-based compound (trade name: Rasmin A, manufactured by Kyoeisha Chemical) was added, and 11.3 parts by weight of triethylamine was added. After the addition, 1067 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30%.

(Example 6)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 110 parts by weight of castor oil-based polyol (HS2G-160R, manufactured by Toyokuni Seiyaku, 2 active hydrogen atoms), and propylene oxide of bisphenol A 27.5 parts by weight of an adduct (polyether BPX-11, manufactured by Asahi Denka Kogyo, 2 active hydrogen atoms), 8.8 parts by weight of trimethylolpropane (3 active hydrogen atoms), dimethylolpropionic acid (active 2) 11 parts by weight of hydrogen atoms, 142.5 parts by weight of dicyclohexylmethane diisocyanate, and 240 parts by weight of methyl ethyl ketone were reacted at 75 ° C. for 4 hours, and the content of free isocyanate groups with respect to the nonvolatile content was 3.9 weights. % Of a methyl ethyl ketone solution of urethane prepolymer. The solution was cooled to 45 ° C., 15 parts by weight of a combination of a mineral oil compound and a petroleum sulfonate compound (trade name: Rasmin A, manufactured by Kyoeisha Chemical Co., Ltd.) was added, and 8.3 parts by weight of triethylamine was added. After neutralization, 771 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer, and then 7.5 parts by weight of ethylenediamine was added to extend the chain. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30%.

(Comparative Example 1)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 200 parts by weight of polytetramethylene ether glycol (Poly THF-1000, manufactured by BASF, number of active hydrogen atoms 2) and 1,4 -20 parts by weight of cyclohexanedimethanol (2 active hydrogen atoms), 6 parts by weight of trimethylolpropane (3 active hydrogen atoms), 15 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), and isophorone diisocyanate 133 Part by weight and 243 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 1.7% by weight based on the nonvolatile content. The solution was cooled to 45 ° C. and neutralized by adding 11.3 parts by weight of triethylamine, and then 962 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. This was decompressed and the solvent was removed at 50 ° C. to obtain a polyurethane water dispersion having a nonvolatile content of about 30%.

(Comparative Example 2)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 200 parts by weight of polytetramethylene ether glycol (Poly THF-1000, manufactured by BASF, number of active hydrogen atoms 2) and 1,4 -20 parts by weight of cyclohexanedimethanol (2 active hydrogen atoms), 6 parts by weight of trimethylolpropane (3 active hydrogen atoms), 15 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), and isophorone diisocyanate 133 Part by weight and 243 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 1.7% by weight based on the nonvolatile content. The solution was cooled to 45 ° C. and neutralized by adding 11.3 parts by weight of triethylamine, and then 962 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. The solution was depressurized and the solvent was removed from the solution at 50 ° C. After that, 19 parts by weight of a mineral oil compound (trade name: Rasmin KP-700, manufactured by Kyoeisha Chemical Co., Ltd.) was added, and polyurethane having a nonvolatile content of about 30% was added. An aqueous dispersion was obtained.

(Comparative Example 3)
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube, 200 parts by weight of polytetramethylene ether glycol (Poly THF-1000, manufactured by BASF, number of active hydrogen atoms 2) and 1,4 -20 parts by weight of cyclohexanedimethanol (2 active hydrogen atoms), 6 parts by weight of trimethylolpropane (3 active hydrogen atoms), 15 parts by weight of dimethylolpropionic acid (2 active hydrogen atoms), and isophorone diisocyanate 133 Part by weight and 243 parts by weight of methyl ethyl ketone were added and reacted at 75 ° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 1.7% by weight based on the nonvolatile content. The solution was cooled to 45 ° C. and neutralized by adding 11.3 parts by weight of triethylamine, and then 962 parts by weight of water was gradually added and emulsified and dispersed using a homogenizer. The solution was depressurized, the solvent was removed from the solution at 50 ° C., and then 25 parts by weight of an emulsion type mineral oil compound (trade name: Rasmin E-208, manufactured by Kyoeisha Chemical Co., Ltd.) was added. A polyurethane water dispersion was obtained.

(Evaluation of water-based paint for metal material surface treatment)
Table 1 shows the formulations of the water-based paints for surface treatment of metal materials of each Example and each Comparative Example. Moreover, while calculating the crosslinking density of each dispersion, the glass transition temperature was measured, and the results are also shown in Table 1. The glass transition temperature is measured using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM) at a frequency of 10 Hz, a temperature rising rate of 2 ° C./min, and the temperature at which the loss elastic modulus (E ″) shows the peak. I read it.

  Moreover, cold rolled steel plate (Nihon Test Panel Co., Ltd .; SPCC-D) is applied as Fe, and electrogalvanized steel sheet (Tayu Equipment Co., Ltd .; Unizinc) and aluminum (Nihon Test Panel Co., Ltd .; A-1100P) are applied as Zn. Using as an object, tests were made on alkali resistance, corrosion resistance and adhesion. The results are shown in Table 2.

<Test method and evaluation criteria>
(1) Alkali resistance: 1 g / m ^{2 of the} water-based paint for surface treatment of metal materials of each Example and each Comparative Example was applied to the above-mentioned application object with a bar coater and dried at PMT (Maximum material temperature) 80 ° C. I got a piece. The appearance color change was observed after the test piece was immersed in a 1% NaOH aqueous solution at room temperature for 5 hours. The evaluation criteria are as follows.

◎… No discoloration ○… Some discoloration △… Some discoloration ×… Many discoloration

(2) Corrosion resistance: 1 g / m ² of each sample was applied to the application target with a bar coater and dried at 80 ° C. PMT to obtain a test piece. This specimen was evaluated using a salt spray test for 24 hours for cold rolled steel sheets, 240 hours for electrogalvanized steel sheets and 1000 hours for aluminum. The evaluation criteria are as follows.

◎… Rust generation rate 5% or less ○… Rust generation rate 5 to 10% or less Δ… Rust generation rate 10 to 50% or less ×… Rust generation rate 50% or more

(3) Adhesion: 1 g / m ² of each sample was applied to the application target with a bar coater and dried at 80 ° C. PMT to obtain a test piece. This test piece was subjected to a 1 mm grid tape (R) peel test. The evaluation criteria are as follows.

◎ ... 100/100
○ ... 90-99 / 100
Δ: 50-90 / 100
X: 0 to 50/100.

<Evaluation results>
The water-based coating composition for surface treatment of a metal material of each example is excellent in alkali resistance, corrosion resistance and adhesion with respect to any of Fe, Zn and Al. In particular, the coating compositions of Examples 5 and 6 are active. Since an oxyethylene derivative of bisphenol A and a castor oil-based polyol are used as the compounds having hydrogen atoms, the evaluation results of alkali resistance and corrosion resistance are very good. In contrast, Comparative Example 1 in which no hydrophobic component was blended, Comparative Example 2 in which a hydrophobic component was added after the urethane prepolymer was dispersed in water, and Comparative Example in which an emulsion type hydrophobic component was added later The composition of 3 could not obtain a satisfactory evaluation result in any evaluation item.

The water-based paint composition of the present invention expresses chemical resistance, corrosion resistance and adhesion to various metal materials, so that metal plates used particularly in automobiles, civil engineering materials, building materials, steel furniture, electrical products, It can be applied to metal materials that require corrosion resistance such as parts.

Claims (4)

  An aqueous coating composition for metal material surface treatment containing a water dispersible resin and a hydrophobic component, wherein the hydrophobic component is added to the water dispersible resin and then dispersed in water together with the water dispersible resin. A water-based coating composition for surface treatment of a metal material, characterized in that   The water-based coating composition for metal material surface treatment according to claim 1, wherein the water-dispersible resin is a water-based polyurethane resin.   The compound having two or more active hydrogen atoms, which is a raw material of the water-based polyurethane resin, contains at least one active hydrogen-containing compound selected from oxyalkylene adducts of bisphenol A, olefinic polyols, and vegetable oil-based polyols. The water-based paint composition for metal material surface treatment according to claim 2. The said hydrophobic component contains at least 1 sort (s) of hydrophobic compound selected from a mineral oil type compound, a sulfonate type compound, a natural wax, and a synthetic wax, The Claim 1 thru | or 3 characterized by the above-mentioned. Water-based paint composition for metal material surface treatment.