TW201906887A - Aurethane resin composition, steel sheet surface treatment agent and steel sheet having the same - Google Patents

Abstract

Provided is a urethane resin composition which has excellent blend stability and is capable of forming a coating film that has excellent corrosion resistance, chemical resistance and adhesion to a substrate. The present invention uses a urethane resin composition which contains a urethane resin (A) that is a reaction product of a polyol (a1) that contains an aromatic polyester polyol (a1-1) and a polyol (a1-2) having an anionic group and a polyisocyanate (a2) and an aqueous medium (B), and which is characterized in that: the aromatic ring concentration in the aromatic polyester polyol (a1-1) is 2.5-5 mol/kg; the polyisocyanate (a2) contains an aliphatic polyisocyanate and/or a polyisocyanate having an alicyclic structure; and the acid value of the urethane resin (A) is within the range of 10-25 mgKOH/g.

Description

   Urethane resin composition, steel plate surface treatment agent, and steel plate having coating film thereof   

The present invention relates to a urethane resin composition, a steel sheet surface treatment agent, and a steel sheet having a coating film thereof.

In recent years, with the increase in metal demand, the demand for coating agents for surface protection of metal substrates, such as steel plates, that is, surface treatment agents for steel plates has increased. For such steel sheet surface treatment agents, corrosion resistance or high chemical resistance can be generally sought to prevent peeling or swelling of a coating film due to corrosion of a metal substrate. Especially for chemical resistance, in the steel industry, which frequently cleans the coating film surface formed on the surface of metal substrates using alkaline detergents, etc., in order to prevent the coating film from peeling or dissolving due to the influence of the detergent, metal Important characteristics such as substrate degradation.

Surface treatment agents for steel plates having the aforementioned characteristics are often required especially for surface protection applications of metal substrates that are prone to rust.

As the steel sheet surface treatment agent, for example, an aqueous resin composition for a metal surface treatment agent is known, which is a metal surface treatment containing a carboxyl group-containing aqueous urethane resin and an aqueous vinyl modified epoxy ester resin. Water-based resin composition, the carboxyl-containing aqueous urethane resin-based polyester polyol, polyisocyanate compound, and polyester amine group obtained by reacting a chain elongator containing a diol component having a carboxyl group in the molecule A formate resin in which the polyester polyol is composed of an acid component and a diol component having no carboxyl group in the molecule (for example, refer to Patent Document 1).

However, the coating film formed by using the water-based resin composition of the metal surface treatment agent described above does not make further progress in terms of chemical resistance and corrosion resistance in terms of preventing deterioration of the metal substrate for a long period of time, and is sometimes insufficient in practical use.

Therefore, a urethane resin composition capable of forming a coating film excellent in corrosion resistance, chemical resistance, and substrate adhesion is sought.

Prior art literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. 2006-321911

The problem to be solved by the present invention is to provide a urethane resin composition which can form a coating film having excellent blending stability, and excellent corrosion resistance, chemical resistance, and substrate adhesion.

As a result of intensive research by the present inventors in order to solve the above-mentioned problems, it was found that by using a urethane resin composition containing a urethane resin, the urethane resin contains The number average molecular weight and the aromatic ring concentration of a specific range of aromatic polyester polyols and polyhydric alcohols having anionic groups "and the reaction products of polyols with specific polyisocyanates can solve the above problems, and thus completed the present invention.

That is, the present invention relates to a urethane resin composition, which is a urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), wherein the amine group The formate resin (A) is a reaction product of a polyol (a1) and a polyisocyanate (a2), and the polyol (a1) contains an aromatic polyester polyol (a1-1) and a polyol having an anionic group (a1-2), the urethane resin composition is characterized in that the aromatic ring concentration in the aromatic polyester polyol (a1-1) is 2.5 to 5 mol / kg, and the polyisocyanate (a2) is In the case of an aliphatic polyisocyanate and / or a polyisocyanate having an alicyclic structure, the urethane resin (A) has an acid value in the range of 10 to 25 mgKOH / g; the present invention also relates to a steel plate surface treatment agent and Steel plate with its coating film.

The urethane resin composition of the present invention has excellent stability when blended, and furthermore, it can form a coating film with excellent corrosion resistance, chemical resistance, and substrate adhesion, so it can be used on the surface of various substrates. Protective use. As the base material to which the urethane resin composition of the present invention is applicable, for example, galvanized steel sheet or aluminized-zinc steel sheet, galvanized-aluminum-magnesium alloy steel sheet, aluminum sheet, aluminum alloy sheet, electromagnetic Metal substrates such as steel plates, copper plates, stainless steel plates; various plastics or their films; glass; paper; wood, etc.

In addition, the urethane resin composition of the present invention is suitable for use in, for example, buildings such as exterior walls and roofs because it can form a coating film that is excellent in corrosion resistance and chemical resistance that can prevent the surface deterioration of the metal substrate. Components; civil components such as guardrails, soundproof walls, drainage ditches; surface coating of various items such as home appliances, industrial machinery, automotive exterior materials, etc.

Aspects of the invention

The urethane resin composition of the present invention is a urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), wherein the urethane resin (A) It is a reactant of a polyol (a1) and a polyisocyanate (a2). The polyol (a1) contains an aromatic polyester polyol (a1-1) and a polyol (a1-2) having an anionic group. The urethane resin composition is characterized in that the aromatic ring concentration in the aforementioned aromatic polyester polyol (a1-1) is 2.5 to 5 mol / kg, and the aforementioned polyisocyanate (a2) contains an aliphatic polyisocyanate and / In the case of a polyisocyanate having an alicyclic structure, the acid value of the aforementioned urethane resin (A) is in the range of 10 to 25 mgKOH / g.

The urethane resin (A) is a polyol (a1) containing an aromatic polyester polyol (a1-1) and a polyol (a1-2) having an anionic group, and Reactant of polyisocyanate (a2). The said reactant may be a reactant containing the said polyol (a1), the said polyisocyanate (a2), and other compounds.

For the aforementioned polyol (a1), it is necessary to use an aromatic polyester polyol (a1-1) and a polyol (a1-2) having an anionic group.

The aromatic polyester polyol (a1-1) can obtain an urethane resin composition with excellent blending stability, and can form excellent corrosion resistance, chemical resistance, and substrate adhesion. For the coating film, an aromatic ring concentration in the range of 2.5 to 5 mol / kg is used. In addition, an aromatic polyester polyol having an aromatic ring concentration in a range of 3 to 4.4 mol / kg is more preferable from the viewpoint of forming a coating film having more excellent corrosion resistance, chemical resistance, and substrate adhesion.

In addition, the aromatic polyester polyol (a1-1) can obtain an urethane resin composition with excellent blending stability, and can form corrosion resistance, chemical resistance, and adhesion to a substrate. The coating film with excellent properties is preferably a number average molecular weight in a range of 750 to 5,000, and more preferably a range of 1,000 to 3,000.

In this specification, the number average molecular weight can be measured using gel permeation chromatography using polystyrene as a standard sample conversion value.

The aromatic polyester polyol (a1-1) can be obtained, for example, by performing an esterification reaction between a polycarboxylic acid and a polyhydric alcohol. Among the polycarboxylic acid and the polyhydric alcohol, at least one of the polycarboxylic acid and the polyhydric alcohol is an aromatic ring.

Examples of the polycarboxylic acid having an aromatic ring include, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phthalic acid, and naphthalenedicarboxylic acid, or esters thereof . Examples of those who do not have an aromatic ring include succinic acid, glutaric acid, adipic acid, maleic acid, pimelic acid, suberic acid, azelaic acid, itaconic acid, sebacic acid, Aliphatic dicarboxylic acids such as chloroendic acid, 1,2,4-butane-tricarboxylic acid, sebacic acid, cyclohexanedicarboxylic acid, dimer acid, and fumaric acid, or esterified products thereof. These polycarboxylic acids or their esterified products may be used alone or in combination of two or more.

Examples of the polyol having an aromatic ring include aromatic diols such as benzyl alcohol, toluene dimethanol, and xylene dimethanol. Examples of those having no aromatic ring include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,8-octanediol. , Aliphatic glycols such as diethylene glycol, triethylene glycol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, neopentyl glycol, etc. These polyols may be used alone or in combination of two or more kinds.

In the esterification reaction when the aforementioned aromatic polyester polyol (a1-1) is produced, it is preferable to use an esterification catalyst for the purpose of promoting the esterification reaction. Examples of the esterification catalyst include metals such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium, and germanium; titanium tetraisopropoxide, titanium tetrabutoxide, titanium acetone titanium oxide, and dibutyl oxide. Tin oxide, dibutyltin diacetate, dibutyltin dilaurate, tin octoate, 2-ethylhexanetin, zinc acetoacetone, zirconium tetrachloride, zirconium tetrachloride tetrahydrofuran complex, hafnium tetrachloride, Samarium tetrachloride tetrahydrofuran complex, germanium oxide, germanium tetraethoxylate and other metal compounds.

In the polyol (a1), the content of the aromatic polyester polyol (a1-1) is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more. It is preferably 99% by mass or less, and more preferably 98% by mass or less.

Examples of the anionic group-containing polyol (a1-2) include an acidic group such as a carboxyl group and a sulfonic acid group, and examples of the anionic group-containing polyol (a1-2) For example, a polyhydric alcohol having a carboxyl group, a polyhydric alcohol having a sulfonic acid group, and the like can be cited.

Furthermore, among the polyol (a1-2) having an anionic group, the aromatic polyester polyol having an anionic group is one included in the aromatic polyester polyol (a1-1).

Examples of the polyhydric alcohol having a carboxyl group include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid. Among them, More preferred is 2,2-dimethylolpropionic acid. Further, a polyester polyol having a carboxyl group obtained by reacting the polyol having a carboxyl group with various polycarboxylic acids may be used.

Examples of the polyol having a sulfonic acid group include 5-sulfonic acid isophthalic acid, sulfonic acid terephthalic acid, 4-sulfonic acid phthalic acid, and 5- (4-sulfonic acid). Acid phenoxy) isophthalic acid and other dicarboxylic acids or their salts; the aforementioned dicarboxylic acid and ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethyl Polyester polyols obtained by reacting low-molecular-weight polyols such as diols and neopentyl glycol; further, the polyester polyols are reacted with rings such as γ-butyrolactone, δ-valerolactone, and ε-caprolactone A polyester polyol obtained by reacting an ester compound.

In the polyol (a1), the content of the polyol (a1-2) having an anionic group is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more. It is preferably 10% by mass or less, more preferably 9% by mass or less, and even more preferably 8% by mass or less.

In the polyol (a1), the total content of the aromatic polyester polyol (a1-1) and the polyol (a1-2) having an anionic group is preferably 70% by mass or more, and more preferably 80 mass% or more, more preferably 90 mass% or more, and more preferably 100 mass% or less.

In view of the fact that the aforementioned anionic group can exhibit good water dispersibility, some or all of them are neutralized with a neutralizing agent (C).

As the aforementioned neutralizing agent (C), a basic compound can be used. From the viewpoint of forming a coating film having excellent chemical resistance, a basic compound having a boiling point of less than 140 ° C is preferred, a basic compound having a boiling point of 135 ° C or less, and a basic compound having a boiling point of 90 ° C or less. Basic compounds having a boiling point of less than 90 ° C are more preferred. The lower limit of the boiling point of the basic compound is, for example, preferably -50 ° C, and more preferably -40 ° C or more. In this specification, the boiling point is expressed at a boiling point of 1013 hPa.

Examples of the basic compound include monomethylamine (boiling point: -6 ° C), dimethylamine (boiling point: 7 ° C), trimethylamine (boiling point: 3 ° C), and monoethylamine. Amine (boiling point: 16.6 ° C), diethylamine (boiling point: 56 ° C), triethylamine (boiling point: 89.5 ° C), monopropylamine (boiling point: 48 ° C), dipropylamine (boiling point: 108 ° C) ), Alkylamines such as tripropylamine (boiling point: 156 ° C); monoethanolamine (boiling point: 170 ° C), diethanolamine (boiling point: 268 ° C), monoisopropanolamine (boiling point: 159 ° C), diisopropyl Alcoholamine (boiling point: 249 ° C), N-methylethanolamine (boiling point: 159 ° C), N, N-dimethylethanolamine (boiling point: 135 ° C), N, N-diethylethanolamine (boiling point: 162 ° C) , 2-amino-2-methyl-1-propanol (boiling point: 166 ° C), 2- (dimethylamino) -2-methyl-1-propanol (boiling point: 163 ° C), N- Alkanolamines such as methyldiethanolamine (boiling point: 245 ° C), N-ethyldiisopropylamine (boiling point: 127 ° C); organic amines such as odorant (boiling point: 129 ° C) or ammonia (boiling point: -33 ° C) )Wait. Among these, from the viewpoint of forming a coating film having excellent chemical resistance, a basic compound having a boiling point of less than 140 ° C is preferred, a basic compound having a boiling point of less than 90 ° C is more preferred, and ammonia is further more preferred. good. Ammonia can also be dissolved in water to form ammonia water and used. In this case, the ammonia concentration in the ammonia water is preferably 1% by mass or more, more preferably 3% by mass or more, preferably 30% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass. the following.

The content of the neutralizing agent (C) is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, based on 100 parts by mass of the total amount of the polyol (a1) and the polyisocyanate (a2). It is more preferably 0.3 parts by mass or more, more preferably 10 parts by mass or less, even more preferably 7 parts by mass or less, still more preferably 5 parts by mass or less.

The polyol (a1) may be used in combination with other polyols as necessary.

In addition, as for the other polyols, for example, a polyester polyol or a polymer other than the aromatic polyester polyol (a1-1) and the polyol (a1-2) having an anionic group may be used. Ether polyols, polycarbonate polyols, polyolefin polyols, and the like. These other polyols may be used alone or in combination of two or more kinds.

Examples of the polyether polyol include those obtained by subjecting one or two or more compounds having two or more active hydrogen atoms as an initiator to addition polymerization of an alkylene oxide. Examples of the compound having two or more active hydrogen atoms include propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, Neopentyl glycol, glycerol, diglycerin, trimethylolethane, trimethylolpropane, water, hexanetriol, and the like. Examples of the alkylene oxide include propylene oxide, butylene oxide, phenylethylene oxide, epichlorohydrin, and tetrahydrofuran. These polyether polyols may be used alone or in combination of two or more kinds.

Examples of the polycarbonate polyol include those obtained by esterifying a carbonic acid and a carbonate with a polyol. Examples of the polyol include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and polyethylene glycol. , Polypropylene glycol, polytetramethylene ether glycol, etc. These polycarbonate polyols may be used alone or in combination of two or more kinds.

As the polyisocyanate (a2) used in the production of the aforementioned urethane resin (A), an aliphatic polyisocyanate and / or a polyisocyanate having an alicyclic structure can be used.

Examples of the aliphatic polyvalent isocyanate include hexamethylene diisocyanate, lysine diisocyanate, and trimethylhexamethylene diisocyanate. These aliphatic polyisocyanates may be used singly or in combination of two or more kinds.

Examples of the polyisocyanate having an alicyclic structure include cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like. These polyisocyanates having an alicyclic structure may be used alone or in combination of two or more kinds.

The ratio of the aliphatic polyisocyanate and / or the polyisocyanate having an alicyclic structure to the polyisocyanate (a2) can be obtained from a urethane resin composition having excellent blending stability, and For forming a coating film having excellent corrosion resistance, chemical resistance, and substrate adhesion, a range of 10 to 100% by mass is preferred, and a range of 20 to 90% by mass is more preferred.

The polyisocyanate (a2) may be used in combination with an aromatic polyisocyanate, if necessary.

Examples of the aromatic polyisocyanate include 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and carbodiimide-modified diphenylmethanediisocyanate. Isocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, and the like.

The method for producing the urethane resin (A) obtained by reacting the polyol (a1) with the polyisocyanate (a2) includes, for example, the step of A method in which the polyol (a1) is mixed with the aforementioned polyisocyanate (a2), and the reaction is performed at a reaction temperature in a range of about 50 ° C to 150 ° C.

The reaction between the polyol (a1) and the polyisocyanate (a2) is performed by, for example, comparing the equivalent ratio of isocyanate groups of the polyisocyanate (a2) to the hydroxyl group of the polyol (a1) in a range of 0.8 to 2.5. It is more preferable to perform in the range of 0.9 to 1.5, and it is particularly preferable to perform in the range of 0.95 to 1.3.

In addition, the urea bond amount in the urethane resin (A) can obtain a urethane resin composition with excellent blending stability, and can form corrosion resistance, chemical resistance, and dense substrate. For a coating film having excellent adhesion, it is preferably less than 250 mmol / kg, and more preferably less than 150 mmol / kg.

In addition, when producing the urethane resin (A), in addition to forming the coating film having excellent hardness, elongation, and flexibility, in addition to the polyol (a1) and the polyisocyanate (a2), If necessary, a chain extender can be used.

Examples of the chain elongating agent include polyamines, hydrazine compounds, and other compounds containing an active hydrogen atom.

Examples of the polyamine include ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, and piperidine. 2,5-dimethylpiperazine , Isophorone diamine, 4,4'-dicyclohexylmethyldiamine, 3,3'-dimethyl-4,4'-dicyclohexylmethyldiamine, 1,4-cyclohexanediamine, etc. Diamine; N-hydroxymethylaminoethylamine, N-hydroxyethylaminoethylamine, N-hydroxypropylaminopropylamine, N-ethylaminoethylamine, N-methylaminopropylamine; two Ethylenetriamine, Ethylenetriamine, Ethylenetetramine, etc. These polyamines may be used alone or in combination of two or more kinds.

Examples of the hydrazine compound include hydrazine, N, N'-dimethylhydrazine, and 1,6-hexamethylenebishydrazine; succinimidine dihydrazine, hexamethylene dihydrazine, and glutaric acid dihydrazine , Sebacin dihydrazine, m-xylylenedihydrazine; β-aminourea propionazine and the like. These hydrazine compounds may be used alone or in combination of two or more.

Examples of the other active hydrogen-containing compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, and 1,4-butane. Diols, diols such as hexamethylene glycol, sucrose, methylene glycol, glycerol, sorbitol; bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl Phenols such as methyl ether, 4,4'-dihydroxydiphenylphosphonium, hydrogenated bisphenol A, hydroquinone, etc .; and water; within the range where the storage stability of the aqueous resin composition of the present invention does not decrease, it may be alone You can use 2 or more types together.

When producing the aforementioned urethane resin (A), alcohol compounds such as methanol, ethanol, propanol, and butanol; ethylene glycol, 1,3-propanediol, 1,3-butanediol, 1, Diol compounds such as 4-butanediol are used as reaction stoppers.

The amount of the reaction stopper is preferably 0.1 part by mass or more, more preferably 1 part by mass or less, more preferably 0.8 with respect to 100 parts by mass of the total amount of the polyol (a1) and the polyisocyanate (a2). Mass parts or less.

Examples of the organic solvent that can be used when producing the urethane resin (A) include, for example, ketone solvents such as acetone and methyl ethyl ketone; Ether solvents such as alkane; acetate solvents such as ethyl acetate and butyl acetate; nitrile solvents such as acetonitrile; amine solvents such as dimethylformamide and N-methylpyrrolidone. These organic solvents may be used alone or in combination of two or more.

The organic solvent may be one of the organic solvents, for example, during the production of the urethane resin (A) or after the production, for safety or to reduce the load on the environment. Partially or completely removed.

Examples of the aqueous medium (B) include water, organic solvents that can be mixed with water, and mixtures thereof. Examples of organic solvents that can be mixed with water include alcohol solvents such as methanol, ethanol, n-propanol, and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; ethylene glycol, diethylene glycol, Polyalkylene glycols such as propylene glycol; Alkyl ether solvents of polyalkylene glycols; L-amine solvents such as N-methyl-2-pyrrolidone. These organic solvents that can be mixed with water can be used alone or in combination of two or more.

In addition, in consideration of safety or reducing the load on the environment, the aqueous medium (B) is preferably water only, or a mixture of water and an organic solvent that can be mixed with water, and more preferably water only. In the aforementioned aqueous medium (B), the content of water is preferably 80% by mass or more, more preferably 90% by mass or more, and the upper limit thereof is 100% by mass.

The aqueous medium (B) is preferably in a range of 30 to 80% by mass in the total amount of the urethane ester composition of the present invention, and more preferably in a range of 50 to 70% by mass.

In the urethane resin composition of the present invention, a cross-linking agent, a plasticizer, an antistatic agent, a wax, a surfactant, a light stabilizer, a flow modifier, a dye, and a leveling agent can be used as necessary. Various additives such as leveling agent, rheology control agent, ultraviolet absorber, antioxidant, photocatalyst compound, inorganic pigment, organic pigment, and extender pigment. When the aforementioned additive is contained, its content is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, based on 100 parts by mass of the urethane resin (A).

Examples of the crosslinking agent include amine resins, aziridine compounds, melamine compounds, epoxy compounds, and the like. An oxazoline compound, a carbodiimide compound, an isocyanate compound, and the like.

In addition, by using the aforementioned surfactant, the blending stability of the urethane resin composition of the present invention can be further improved. When a surfactant is used, it is within a range of 20 parts by mass or less based on 100 parts by mass of the aforementioned urethane resin (A) from the viewpoint of maintaining the adhesiveness of the substrate of the obtained coating film. It is better to use, and it is better not to use as much as possible.

In the urethane resin composition of the present invention, a curing agent or a curing catalyst may be used in combination, if necessary, within a range that does not impair the effects of the present invention.

Examples of the hardener include a compound having a silanol group and / or a hydrolyzable silicon group, a polyepoxy compound, and a polysiloxane compound. An oxazoline compound, a polyisocyanate, and the like.

Among them, it is preferable to use a compound having a silanol group and / or a hydrolyzable silicon group in terms of the aforementioned hardener in terms of forming a crosslinked coating film having excellent corrosion resistance. In particular, when the urethane resin composition of the present invention is used as a surface treatment agent for a steel sheet, the hydrolyzable silyl group or silanol group of the aforementioned compound improves the adhesion between the substrate and the metal. As a result, It can form a coating film with excellent corrosion resistance.

The hydrolyzable silicon group is preferable because, for example, the alkoxysilyl group has high crosslinkability and improved corrosion resistance. Especially for alkoxysilyl groups, trimethoxysilyl groups and triethoxysilyl groups are particularly excellent because of their excellent crosslinkability and improved corrosion resistance.

Examples of the compound having a silanol group and / or a hydrolyzable silyl group include, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidyloxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane , 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane and other epoxy silane compounds; γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ -Aminosilanes such as aminopropylmethyldimethoxysilane and γ-aminopropylmethyldiethoxysilane.

Among them, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, because The coating film has a higher cross-linking density and a better chemical resistance or corrosion resistance, so it is preferable.

The compound having a silanol group and / or a hydrolyzable silicon group can form a coating film with excellent corrosion resistance and can obtain the urethane resin composition of the present invention with excellent blending stability. The urethane resin (A) in parts by mass is preferably used in a range of 0.01 to 10 parts by mass.

Examples of the curing catalyst that can be used in the urethane resin composition of the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methoxide, and tetraisopropyl titanate. Ester, tetra-n-butyl titanate, tin octoate, lead octoate, cobalt octoate, zinc octoate, calcium octoate, zinc naphthenate, cobalt naphthenate, di-n-butyltin diacetate, di-n-butyltin dioctanoate, di-n-butyltin Butyl tin dilaurate, di-n-butyl tin maleate, p-toluenesulfonic acid, trichloroacetic acid, phosphoric acid, monoalkyl phosphoric acid, dialkyl phosphoric acid, monoalkyl phosphorous acid, dialkyl phosphorous acid, and the like.

In addition, the urethane resin composition of the present invention may contain an emulsifier, a dispersion stabilizer, or a leveling / leveling agent as necessary. However, from the viewpoint of suppressing the decrease in water resistance of the crosslinked coating film, It is preferable that it is not contained, and it is more preferable that it is 0.5 mass% or less corresponding to the non-volatile component of the said urethane resin composition.

The urethane resin composition of the present invention can be used for coating various substrates for the purpose of protecting the surface of various substrates and giving creativity to various substrates.

The aforementioned substrates include, for example, metal substrates such as galvanized steel plates or aluminized-zinc steel plates, galvanized-aluminum-magnesium alloy steel plates, aluminum plates, aluminum alloy plates, electromagnetic steel plates, copper plates, and stainless steel plates; various plastics Or its film; glass; paper; wood, etc.

In addition, the urethane resin composition of the present invention can be suitably used in, for example, construction members such as outer walls and roofs; civil members such as guardrails, sound insulation walls, and drainage channels; household appliances, industrial machinery, and automotive exterior materials Surface coating of articles, etc.

In addition, the urethane resin composition of the present invention can be used as a surface treatment agent for steel plates because it can form a coating film having excellent corrosion resistance and chemical resistance that can prevent the surface of the metal substrate from being deteriorated.

The steel sheet surface treatment agent of the present invention can form a coating film having excellent chemical resistance including acid resistance and alkali resistance even if the crosslinked coating film has a film thickness of about 5 μm. Moreover, even if the crosslinked coating film has a film thickness of about 1 μm, a coating film having excellent chemical resistance including acid resistance and alkali resistance can be formed.

The steel sheet surface treatment agent of the present invention can be coated on a substrate, dried and hardened to form a coating film.

Examples of the coating method include a spray method, a curtain coating method, a flow coating method, a roll coating method, a bristle coating method, and a dipping method.

The aforementioned drying may be performed naturally at normal temperature, or may be dried by heating. Heating and drying are usually performed at 40 to 250 ° C. for about 1 to 600 seconds.

The steel sheet having the coating film of the steel sheet surface treatment agent of the present invention includes, for example, galvanized steel sheets used for automobiles, home appliances, building materials, etc., coated steel sheets such as aluminum-zinc alloy steel sheets, and zinc-plated steel sheets. Aluminum-magnesium alloy steel plate, aluminum plate, aluminum alloy plate, electromagnetic steel plate, copper plate, stainless steel plate, etc.

Examples

Hereinafter, the present invention will be specifically described using examples and comparative examples.

    (Synthesis example 1: Synthesis of aromatic polyester polyol (1))    

In a nitrogen-substituted container equipped with a thermometer, a nitrogen introduction tube, and a stirrer, 13 parts by mass of ethylene glycol, 22 parts by mass of neopentyl glycol, 23 parts by mass of phthalic acid, and 23 parts by mass of The reaction of phthalic acid and 10 parts by mass of adipic acid yielded an aromatic polyester polyol (1) [number average molecular weight: 1,000, aromatic ring concentration: 3.5 mol / kg].

    (Synthesis example 2: Synthesis of aromatic polyester polyol (2))    

In a nitrogen-substituted container provided with a thermometer, a nitrogen introduction tube, and a stirrer, 12 parts by mass of ethylene glycol, 20 parts by mass of diethylene glycol, 28 parts by mass of phthalic acid, and 28 parts by mass of The reaction with phthalic acid gave an aromatic polyester polyol (2) [number average molecular weight: 1,700, aromatic ring concentration: 4.5 mol / kg].

    (Synthesis Example 3: Synthesis of Aromatic Polyester Polyol (3))    

In a nitrogen-substituted container provided with a thermometer, a nitrogen introduction tube, and a stirrer, 12 parts by mass of ethylene glycol, 21 parts by mass of neopentyl glycol, 27 parts by mass of phthalic acid, and 27 parts by mass of The reaction with phthalic acid gave an aromatic polyester polyol (3) [number average molecular weight: 1,000, aromatic ring concentration: 4.3 mol / kg].

    (Synthesis example 4: Synthesis of aromatic polyester polyol (4))    

In a nitrogen-substituted container provided with a thermometer, a nitrogen introduction tube, and a stirrer, 12 parts by mass of ethylene glycol, 24 parts by mass of neopentyl glycol, 32 parts by mass of phthalic acid, and 32 parts by mass of The reaction with phthalic acid gave an aromatic polyester polyol (4) [number average molecular weight: 2,600, aromatic ring concentration: 3.4 mol / kg].

    (Synthesis example 5: Synthesis of aromatic polyester polyol (5))    

In a nitrogen-substituted container provided with a thermometer, a nitrogen introduction tube, and a stirrer, 53 parts by mass of diethylene glycol and 47 parts by mass of phthalic acid were reacted to obtain an aromatic polyester polyol (5) [Number Average molecular weight: 540, aromatic ring concentration: 3.1 mol / kg].

    (Synthesis example 6: Synthesis of aromatic polyester polyol (6))    

In a nitrogen-substituted container provided with a thermometer, a nitrogen introduction tube, and a stirrer, 73 parts by mass of 2,2 '-[isopropylidenebis [(p-phenylene) (oxy)]] diethanol, 16 parts by mass of dimethyl 2,6-naphthalene dicarboxylate, 9 parts by mass of terephthalic acid, and 2 parts by mass of phthalic anhydride were reacted to obtain an aromatic polyester polyol (6) [number average molecular weight : 1,000, aromatic ring concentration: 6.8 mol / kg].

    (Synthesis example 7: Synthesis of polyester polyol (7))    

In a nitrogen-substituted container equipped with a thermometer, a nitrogen introduction tube, and a stirrer, 32 parts by mass of 1,6-hexanediol, 15 parts by mass of neopentyl glycol, and 53 parts by mass of adipic acid were reacted to obtain Polyester polyol (7) [number average molecular weight: 2,000, aromatic ring concentration: 0 mol / kg].

    (Example 1: Preparation of urethane resin composition (1))    

By adding 79.6 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.1 parts by mass of 2,2-dimethylolpropionic acid, and 17.3 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, 0.2 mass parts of methanol was added to the organic solvent solution of the said urethane prepolymer, and it was made to react at 60 degreeC, and the reaction of an isocyanate component was stopped completely. Then it was cooled to 40 ° C, and by adding 8 parts by mass of 5% ammonia water, one or all of the carboxyl groups of the urethane prepolymer were partially or completely neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (1) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (1) had an acid value of 13 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 2: Preparation of urethane resin composition (2))    

By adding 75.1 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.1 parts by mass of 2,2-dimethylolpropionic acid, and 21.8 parts by mass of isophor A ketone diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, 0.2 parts by mass of methanol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the mixture was reacted at 60 ° C to completely stop the reaction of the isocyanate component. Then it was cooled to 40 ° C, and by adding 8 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (2) having a nonvolatile component content of 30% by mass was obtained by aging and desolvation. The urethane resin composition (2) had an acid value of 13 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 3: Preparation of urethane resin composition (3))    

By adding 71.9 parts by mass of the aromatic polyester polyol (2) obtained in Synthesis Example 2 to the reaction vessel, 3.1 parts by mass of 2,2-dimethylolpropionic acid, and 25.0 parts by mass of 4,4 '-Dicyclohexylmethane diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at the molecular end.

Then, 0.2 mass parts of methanol was added to the organic solvent solution of the said urethane prepolymer, and it was made to react at 60 degreeC, and the reaction of an isocyanate component was stopped completely. Then it was cooled to 40 ° C, and by adding 8 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (3) having a nonvolatile component content of 30% by mass was obtained by aging and desolvation. The urethane resin composition (3) had an acid value of 13 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 4: Preparation of urethane resin composition (4))    

By adding 79.3 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.1 parts by mass of 2,2-dimethylolpropionic acid, and 8.8 parts by mass of hexamethylene A diisocyanate, 8.8 parts by mass of toluene diisocyanate, and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, 0.6 part by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then it was cooled to 40 ° C, and by adding 8 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (4) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (4) had an acid value of 13 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 5: Preparation of urethane resin composition (5))    

By adding 82.7 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to a reaction vessel, 4.3 parts by mass of 2,2-dimethylolpropionic acid, and 6.5 parts by mass of hexamethylene A diisocyanate, 6.5 parts by mass of xylylene diisocyanate, and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, 0.6 part by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then it was cooled to 40 ° C, and by adding 11 parts by mass of 5% ammonia water, a part or all of the carboxyl groups of the urethane prepolymer was neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (5) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (5) had an acid value of 18 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 6: Preparation of urethane resin composition (6))    

By adding 74.6 parts by mass of the aromatic polyester polyol (2) obtained in Synthesis Example 2 to the reaction vessel, 4.3 parts by mass of 2,2-dimethylolpropionic acid, and 6.3 parts by mass of isophorone A mixed solution of diisocyanate, 14.7 parts by mass of xylylene diisocyanate, and 67 parts by mass of methyl ethyl ketone, and reacted at 70 ° C to obtain an organic urethane prepolymer having an isocyanate group at the molecular end. Solvent solution.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then it was cooled to 40 ° C, and by adding 11 parts by mass of 5% ammonia water, a part or all of the carboxyl groups of the urethane prepolymer was neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (6) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (6) had an acid value of 18 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 7: Preparation of urethane resin composition (7))    

By adding 69.8 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to a reaction vessel, 4.3 parts by mass of 2,2-dimethylolpropionic acid, and 7.8 parts by mass of 4,4 ' -Dicyclohexylmethane diisocyanate, 18.1 parts by mass of diphenylmethane diisocyanate, 67 parts by mass of methyl ethyl ketone, and reacted at 70 ° C to obtain an urethane prepolymer having an isocyanate group at the molecular end Organic solvent solution.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then it was cooled to 40 ° C, and 3 parts by mass of triethylamine was added to neutralize a part or all of the carboxyl groups of the urethane prepolymer. Further, 333 parts by mass of water was added and fully Stirring to obtain an aqueous dispersion of a urethane resin, followed by aging and desolvation, to obtain a urethane resin composition (7) in which a nonvolatile component accounts for 30% by mass. The urethane resin composition (7) had an acid value of 18 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 8: Preparation of urethane resin composition (8))    

By adding 75.0 parts by mass of the aromatic polyester polyol (3) obtained in Synthesis Example 3 to the reaction vessel, 5.5 parts by mass of 2,2-dimethylolpropionic acid, and 19.5 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, 0.6 part by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. After cooling to 40 ° C, 14% by mass of 5% ammonia water was added to neutralize a part or all of the carboxyl groups of the urethane prepolymer, and 333 parts by mass of water was further added to fully neutralize the carboxyl group. The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (8) having a nonvolatile component content of 20% by mass was obtained by aging and desolvation. The urethane resin composition (8) had an acid value of 23 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 9: Preparation of urethane resin composition (9))    

By adding 82.3 parts by mass of the aromatic polyester polyol (4) obtained in Synthesis Example 4 to the reaction vessel, 5.5 parts by mass of 2,2-dimethylolpropionic acid, and 12.2 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. After cooling to 40 ° C, 14% by mass of 5% ammonia water was added to neutralize a part or all of the carboxyl groups of the urethane prepolymer, and 333 parts by mass of water was further added to fully neutralize The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (9) having a nonvolatile component content of 20% by mass was obtained by aging and desolvation. The urethane resin composition (9) had an acid value of 23 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 10: Preparation of urethane resin composition (10))    

By adding 71.5 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 24.4 parts by mass of isophor A ketone diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, the organic solvent solution of the aforementioned urethane prepolymer was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, a part or all of the carboxyl groups of the aforementioned urethane prepolymer were added. Neutralize by adding 5 parts by mass of 10% piperazine Aqueous solution and 333 parts by mass of water, and sufficiently stirred to obtain an aqueous dispersion of a urethane resin, followed by ripening and desolvation, to obtain a urethane resin having a nonvolatile component of 30% by mass Composition (10). The urethane resin composition (10) had an acid value of 15 mgKOH / g and a urea bond amount of 59 mmol / kg.

    (Example 11: Preparation of urethane resin composition (11))    

By adding 69.3 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 26.5 parts by mass of isophor A ketone diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, the organic solvent solution of the aforementioned urethane prepolymer was cooled to 40 ° C., and 3 parts by mass of triethylamine was added to part of the carboxyl group of the aforementioned urethane prepolymer. Or completely neutralize, and further add 0.8 parts by mass of an 80% hydrazine aqueous solution and 333 parts by mass of water, and stir thoroughly to obtain an aqueous dispersion of a urethane resin, and then, by aging and desolvation, obtain The urethane resin composition (11) in which the nonvolatile component accounts for 30% by mass. The urethane resin composition (11) had an acid value of 15 mgKOH / g and a urea bond amount of 210 mmol / kg.

    (Example 12: Preparation of urethane resin composition (12))    

By adding 84.4 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 1.2 parts by mass of hexamethylene A diisocyanate, 10.8 parts by mass of toluene diisocyanate, and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (12) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (12) had an acid value of 15 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 13: Preparation of urethane resin composition (13))    

By adding 83.2 parts by mass of the aromatic polyester polyol (5) obtained in Synthesis Example 5 to the reaction vessel, 4.3 parts by mass of 2,2-dimethylolpropionic acid, and 11.3 parts by mass of hexamethylene A diisocyanate, 1.3 parts by mass of toluene diisocyanate, and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Then, in the organic solvent solution of the aforementioned urethane prepolymer, it was cooled to 40 ° C, 0.6 parts by mass of 1,3-butanediol was added, and the reaction was performed at 70 ° C to completely stop the isocyanate component reaction. By adding 9 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and stirring thoroughly, amino bases were obtained. The aqueous dispersion of the ester resin was then aged and desolvated to obtain a urethane resin composition (13) having a nonvolatile component content of 30% by mass. The urethane resin composition (13) had an acid value of 15 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 14: Preparation of urethane resin composition (14))    

By adding 75.1 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 3.1 parts by mass of 2,2-dimethylolpropionic acid, and 21.8 parts by mass of isophor A ketone diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it cooled to 40 degreeC, and added 2 mass parts of 2-amino-2-methyl-1-propanol, and neutralized part or all of the carboxyl group which the said urethane prepolymer had, and further By adding 333 parts by mass of water and sufficiently stirring, an aqueous dispersion of the urethane resin was obtained, and then by curing and desolvation, a urethane resin having a nonvolatile component content of 30% by mass was obtained. Composition (14). The urethane resin composition (14) had an acid value of 13 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Example 15: Preparation of urethane resin composition (15))    

An aromatic polyester polyol (1) obtained by adding 66.6 parts by weight of Synthesis Example 1 to a reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 27.6 parts by mass of isophor A ketone diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, the organic solvent solution of the aforementioned urethane prepolymer was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, a part or all of the carboxyl groups of the aforementioned urethane prepolymer Neutralize by adding 23% by mass of 10% piperazine Aqueous solution and 333 parts by mass of water, and sufficiently stirred to obtain an aqueous dispersion of a urethane resin, followed by ripening and desolvation, to obtain a urethane resin having a nonvolatile component of 30% by mass Composition (15). The urethane resin composition (15) had an acid value of 15 mgKOH / g and a urea bond amount of 262 mmol / kg.

    (Comparative Example 1: Preparation of urethane resin composition (C1))    

By adding 78.7 parts by mass of the aromatic polyester polyol (6) obtained in Synthesis Example 6 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 17.7 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (C1) having a nonvolatile component content of 30% by mass was obtained by aging and desolvation. The urethane resin composition (C1) had an acid value of 15 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Comparative Example 2: Preparation of urethane resin composition (C2))    

By adding 78.1 parts by mass of the aromatic polyester polyol (3) obtained in Synthesis Example 3 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 18.3 parts by mass of toluene diisocyanate , 67 parts by mass of methyl ethyl ketone, and reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (C2) having a nonvolatile component content of 30% by mass was obtained by aging and desolvation. The urethane resin composition (C2) had an acid value of 15 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Comparative Example 3: Preparation of urethane resin composition (C3))    

By adding 81.9 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 1.9 parts by mass of 2,2-dimethylolpropionic acid, and 16.2 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then it was cooled to 40 ° C, and by adding 5 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (C3) having a nonvolatile component content of 30% by mass was obtained by aging and desolvation. The urethane resin composition (C3) had an acid value of 8 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Comparative Example 4: Preparation of urethane resin composition (C4))    

By adding 72.7 parts by mass of the aromatic polyester polyol (1) obtained in Synthesis Example 1 to the reaction vessel, 6.7 parts by mass of 2,2-dimethylolpropionic acid, and 20.6 parts by mass of hexamethylene The organic diisocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of an urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it cooled to 40 degreeC, 17 mass parts of 5% ammonia water was added, and some or all of the carboxyl groups which the said urethane prepolymer had were neutralized, and 333 mass parts of water was further added and fully The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (C4) having a nonvolatile component content of 20% by mass was obtained by aging and desolvation. The urethane resin composition (C4) had an acid value of 28 mgKOH / g and a urea bond amount of 0 mmol / kg.

    (Comparative Example 5: Preparation of urethane resin composition (C5))    

By adding 84.8 parts by mass of the polyester polyol (7) obtained in Synthesis Example 7 to the reaction vessel, 3.6 parts by mass of 2,2-dimethylolpropionic acid, and 11.6 parts by mass of hexamethylene diacetate An isocyanate and 67 parts by mass of methyl ethyl ketone were reacted at 70 ° C. to obtain an organic solvent solution of a urethane prepolymer having an isocyanate group at a molecular terminal.

Next, 0.6 parts by mass of 1,3-butanediol was added to the organic solvent solution of the aforementioned urethane prepolymer, and the reaction was performed at 70 ° C. to completely stop the isocyanate component from reacting. Then, it was cooled to 40 ° C, and by adding 9 parts by mass of 5% ammonia water, some or all of the carboxyl groups of the urethane prepolymer were neutralized, and further by adding 333 parts by mass of water and sufficiently The aqueous dispersion of the urethane resin was obtained by stirring, and then the urethane resin composition (C5) containing 30% by mass of nonvolatile components was obtained by aging and desolvation. The urethane resin composition (C5) had an acid value of 15 mgKOH / g and a urea bond amount of 0 mmol / kg.

The number average molecular weight of the aromatic polyester polyol is a value obtained by measuring by a gel permeation chromatography (GPC) method under the following conditions.

Measuring device: High-speed GPC device ("HLC-8220 GPC" manufactured by Tosoh Corporation)

Column: The following Columns manufactured by Tosoh Corporation are connected in series and used.

`` TSKgel G5000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G4000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G3000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G2000 '' (7.8mmI.D. × 30cm) × 1

Detector: RI (differential refractometer)

Column temperature: 40 ℃

Eluent: Tetrahydrofuran (THF)

Flow rate: 1.0mL / min

Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)

Standard sample: Use the following standard polystyrene to make a calibration line.

    (Standard polystyrene)    

"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation

"TSKgel Standard Polystyrene F-128" made by Tosoh Corporation

"TSKgel Standard Polystyrene F-288" made by Tosoh Corporation

"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

The following evaluations were performed using the urethane resin composition obtained by the said Example and the comparative example.

    [Evaluation method of blending stability]    

100 parts of the urethane resin composition obtained in Examples 1 to 15 and Comparative Examples 1 to 5 were added with 2 parts of a 10% by mass aqueous ammonium zirconium carbonate solution, and stored at 40 ° C for 6 hours. It was filtered and evaluated according to the following criteria.

：: The residue (agglomerate) is less than 1%.

：: The residue (agglomerate) is 1% or more and less than 5%.

Δ: The residue (agglomerate) is 5% or more and less than 20%.

X: The residue (agglutinate) is 20% or more.

    [Manufacture of test body]    

On a 55 mass% aluminum-zinc alloy-coated steel sheet not subjected to a surface treatment, the urethane resin composition obtained in Examples 1 to 15 and Comparative Examples 1 to 5 was coated in a thickness of 1 μm, and the thickness was 250 μm. It dried at 10 degreeC for 10 second, and produced the test body.

    [Evaluation method of coating film corrosion resistance]    

The surface of the coating film constituting the aforementioned test body was cut with a cutter to a depth of the base material, and a salt water spray test was performed with a salt water spray tester manufactured by Suga Test Instruments Co., Ltd., and visually determined. The area where rust occurred after 240 hours was evaluated. It measured based on the JIS test method (JIS Z2371: 2000).

：: The area where rust is generated is less than 10% of the entire surface of the coating film.

○: The area where rust is generated is 10% or more and less than 40% of the entire surface of the coating film.

△: The area where rust is generated is 40% or more and less than 70% of the entire surface of the coating film.

×: The area where rust is generated is 70% or more of the entire surface of the coating film.

    [Evaluation method of chemical resistance (alkali resistance)]    

Using the test body, the deterioration state of the coating film after being immersed in a 1% by mass sodium hydroxide aqueous solution for 5 hours was visually evaluated on the basis of the following criteria.

：: The area where blackening or discoloration occurs to brown is less than 10% of the entire surface of the coating film.

○: The area where blackening or discoloration occurs to brown is 10% or more and less than 40% of the entire coating film surface.

△: The area where blackening or discoloration occurs to brown is 40% or more and less than 70% of the entire surface of the coating film.

×: The area where blackening or discoloration occurs to brown is 70% or more of the entire surface of the coating film.

    [Evaluation method of chemical resistance (ethanol resistance)]    

On the surface of the base material containing polyethylene terephthalate, the urethane resin compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 5 were coated in a thickness of 10 μm and dried at 80 ° C. 5 minutes to make a test body. The film-forming surface of the obtained test body was subjected to a rubbing test 10 times with absorbent cotton impregnated with 98% by volume of ethanol, the state of the film was visually observed, and the solvent resistance was evaluated according to the following criteria.

◎: No change in film

○: The surface of the membrane remains after rubbing

△: Although the substrate is not exposed, the film is swollen and dissolved

×: The substrate is exposed

    [Evaluation method of substrate adhesion]    

After the test body was immersed in pure water for 24 hours, the coating film was cut transversely, and the state of peeling with an adhesive tape was evaluated according to the following criteria.

：: No abnormality in the coating film.

○: A slight amount of coating film (area of 5% or less) floats.

(Triangle | delta): The coating film floats a little (area more than 5% and 60% or less).

×: The coating film appeared to float (more than 60% of the area).

Table 1 shows the compositions and evaluation results of the urethane resin compositions (1) to (15) prepared in Examples 1 to 15.

Table 2 shows the composition and evaluation results of the urethane resin compositions (C1) to (C5) prepared in Comparative Examples 1 to 5.

From the evaluation results of Examples 1 to 15 shown in Table 1, it was confirmed that the blending stability of the urethane resin composition of the present invention is excellent, and that the urethane resin composition of the present invention is used. The obtained coating film was excellent in corrosion resistance, chemical resistance, and substrate adhesion.

On the other hand, Comparative Example 1 is an example in which the aromatic ring concentration in the aromatic polyester polyol exceeds the range of the present invention, that is, 6.8 mol / kg. It was confirmed that the coating film obtained using the urethane resin composition of Comparative Example 1 was excellent in chemical resistance (ethanol resistance) and substrate adhesion, but had corrosion resistance and chemical resistance (alkali resistance). Sex) is significantly insufficient.

Comparative Example 2 is an example in which an aliphatic polyisocyanate and / or a polyisocyanate having an alicyclic structure is not used. The coating film obtained using the urethane resin composition of Comparative Example 2 was the same as Comparative Example 1. It was confirmed that although the chemical resistance (ethanol resistance) and the substrate adhesion were excellent, the corrosion resistance and Chemical resistance (alkaline resistance) is significantly insufficient.

Comparative Example 3 is an example in which the urethane resin has an acid value outside the range of the present invention, that is, 8 mgKOH / g. It was confirmed that the coating film obtained by using the urethane resin composition of Comparative Example 3 had excellent corrosion resistance and chemical resistance, but was significantly insufficient in chemical resistance (alkali resistance).

Comparative Example 5 is an example in which an aromatic polyester polyol is not used. It was confirmed that the coating film obtained by using the urethane resin composition of Comparative Example 5 had excellent substrate adhesion, but was significantly insufficient in chemical resistance.

Claims (7)

    A urethane resin composition comprising a urethane resin (A) and an aqueous medium (B), wherein the urethane resin (A) It is a reactant of a polyol (a1) and a polyisocyanate (a2). The polyol (a1) contains an aromatic polyester polyol (a1-1) and a polyol (a1-2) having an anionic group. The urethane resin composition is characterized in that the aromatic ring concentration in the aromatic polyester polyol (a1-1) is 2.5 to 5 mol / kg, and the polyisocyanate (a2) contains an aliphatic polyisocyanate and / In the case of a polyisocyanate having an alicyclic structure, the acid value of the urethane resin (A) is in the range of 10 to 25 mgKOH / g.         For example, the urethane resin composition of claim 1, wherein the ratio of the aliphatic polyisocyanate and / or the polyisocyanate having an alicyclic structure in the polyisocyanate (a2) is 10 to 100% by mass. range.         For example, the urethane resin composition of claim 1 or 2, wherein the urea bond amount in the urethane resin (A) is less than 250 mmol / kg.         The urethane resin composition according to any one of claims 1 to 3, wherein the urethane resin composition further contains a neutralizing agent (C).         The urethane resin composition according to claim 4, wherein the neutralizing agent (C) is a basic compound having a boiling point of less than 140 ° C.         A surface treatment agent for a steel sheet, comprising the urethane resin composition according to any one of claims 1 to 5.         A steel plate characterized by having a coating film of a steel plate surface treating agent as claimed in claim 6.