JP6026761B2 - Two-component polyurethane coating composition - Google Patents

Description

  The present invention relates to a two-component polyurethane coating composition applicable to a metal surface, which is suitable for forming a coating film having antirust properties and excellent weather resistance.

  For the purpose of suppressing the occurrence of rust on metal surfaces such as doors, various pipes, and handrails used in buildings, etc., a paint finish is applied in which a rust-preventive primer is applied and a top coat is applied thereon.

  For example, in Patent Document 1, a hydroxyl group-containing non-aqueous dispersion resin, a hydroxyl group-containing solvent-soluble resin having chelate-forming ability, an undercoating material composition containing an isocyanate compound, and the undercoating material composition are applied, and then the overcoating material A coating method for coating is disclosed.

  According to such an undercoating material composition, an undercoating film having both sealing properties and overcoating compatibility with a rust surface can be formed with a small number of coatings even on a metal surface on which rust has remarkably occurred.

  In recent years, there has been a demand for a so-called bottom-up combination paint that can be used for both undercoating and overcoating with a single paint, and development of a paint having weather resistance and rust resistance over a long period of time is required. However, generally, the rust prevention and weather resistance of the coating film are contradictory, and it is extremely difficult to achieve both.

  Patent Documents 2 to 5 propose a two-component coating composition that uses an acrylic resin, an epoxy resin, an organosilane-containing main agent, and an amine curing agent as a lower and upper combined coating composition.

  According to these coating compositions, it is possible to form a coating film excellent in both rust prevention and weather resistance, which is considered difficult, and can be applied as a lower and upper combined coating.

  By the way, blending a rust preventive pigment in order to impart rust preventive properties to a coating film is widely performed, and in recent years, a non-chromium rust preventive pigment has been selected in consideration of the environment.

  Many non-chromium rust preventive pigments such as zinc phosphate, aluminum tripolyphosphate, and zinc molybdate have been put on the market, and various primers have been proposed as a combination of non-chromium pigments.

  For example, Patent Document 6 discloses a rust preventive pigment composition containing vanadium compounds, silica fine particles, and phosphoric acid metal salts in specific ratios, and Patent Document 7 discloses specific vanadium compounds, calcium compounds, and metal salts. A rust preventive pigment composition containing a phosphate metal salt whose metal is Zn, Al or Mg in a specific ratio is disclosed.

  However, the compositions described in Patent Documents 6 and 7 are heat-curable, are intended to improve rust prevention, and satisfy long-term outdoor weather resistance as required for lower and upper combined paints. Not a thing.

JP 2004-143423 A JP 2002-167545 A JP 2002-167546 A JP 2004-5403 A JP 2004-51943 A JP 2008-222833 A JP 2008-222835 A

  An object of the present invention is to provide a coating composition applicable to a metal surface, which is suitable for forming a coating film having rust prevention properties and excellent weather resistance.

  As a result of intensive studies on the above problems, the present inventors have found that a two-component polyurethane obtained by mixing a main component (I) containing a hydroxyl group-containing resin and a curing agent component (II) containing a polyisocyanate before coating. It has been found that the above-mentioned problems can be solved by including a rust-preventive pigment composition having a specific composition in the coating composition, and the present invention has been achieved.

That is, the present invention
1.
A main component (I) containing a hydroxyl group-containing resin (A) and a rust preventive pigment composition (B) containing a hydroxyl group-containing acrylic resin having a hydroxyl value per solid content of 5 to 80 mg KOH / g, and a polyisocyanate compound (C) A two-component polyurethane coating composition obtained by mixing a curing agent component (II) containing the coating composition before coating,
The rust preventive pigment composition (B) contains both silica (b1) and phosphate metal salt (b2) as part of its components, and the phosphate metal salt (b2) contains at least magnesium as a metal. A salt of at least one acid selected from phosphoric acid, phosphorous acid, and tripolyphosphoric acid,
The rust preventive pigment composition (B) is 10% by weight of the rust preventive pigment composition (B) with respect to a 5% by weight sodium chloride aqueous solution, stirred at 25 ° C. for 6 hours, allowed to stand for 24 hours and precipitated The organic solvent-based room temperature curable two-component polyurethane coating composition, wherein the total amount of dissolved elements measured by ICP emission spectrometry is 300 μg / ml or less ,
2.
Item 2. The use ratio of silica (b1) and phosphate metal salt (b2) in the antirust pigment composition (B) is in the range of 10/90 to 90/10 in terms of the former / latter mass ratio. Two-component polyurethane coating composition,
3.
Resin total solid content in which the content of the zinc-based anticorrosive pigment contained in the antirust pigment composition (B) is 50% by mass or less based on the mass of the antirust pigment composition (B) and contained in the main component (I) The two-component polyurethane coating composition according to item 1 or 2, which is 5 parts by mass or less based on 100 parts by mass per minute,
4).
Any 1 item | term of Claims 1 thru | or 3 with which the compounding quantity of a rust preventive pigment composition (B) exists in the range of 3-20 mass parts on the basis of 100 mass parts of resin total solid content contained in main ingredient component (I). The two-component polyurethane coating composition according to the item,
5).
The two-component polyurethane coating composition according to any one of items 1 to 4 , further comprising a silane coupling agent,
6).
The present invention relates to a coating method characterized in that a two-component polyurethane coating composition according to any one of items 1 to 5 is applied to an object to be coated.

  The polyurethane paint composition of the present invention has an appropriate viscosity at the time of painting and has excellent workability for coating, and the formed coating film has high durability with excellent rust prevention and weather resistance. is there.

  The polyurethane coating composition of the present invention comprises a main component (I) containing a hydroxyl group-containing resin (A) and an antirust pigment composition (B) and a curing agent component (II) containing a polyisocyanate compound (C) before coating. It is a two-pack type coating composition obtained by mixing the two. Hereinafter, it demonstrates in order.

<Hydroxyl-containing resin (A)>
In the two-component polyurethane coating composition of the present invention, the hydroxyl group-containing resin (A), which is a material capable of forming a polyurethane coating film having both weather resistance and rust prevention properties together with the polyisocyanate compound (C) described later, As long as it is a hydroxyl group-containing resin having a film-forming ability that can be generally used in the field, it can be used without particular limitation. As a typical example, an acrylic resin, an alkyd resin, or a polyester resin containing at least two hydroxyl groups in the molecule An epoxy resin, a fluororesin, a vinyl chloride resin, a silicon resin; one or two or more mixed resins such as a modified resin obtained by modifying these two or more resins can be mentioned.

  As such a hydroxyl group-containing resin (A), it is desirable from the viewpoint of the weather resistance of the coating film formed from the coating composition of the present invention that it contains a hydroxyl group-containing acrylic resin as a part of its components.

  The production method of such a hydroxyl group-containing acrylic resin is not particularly limited, and may be produced by a conventional method such as radical polymerization using an azo compound or peroxide as an initiator, or a commercially available product may be used. Is also possible.

  As the polymerizable unsaturated monomer constituting the hydroxyl group-containing acrylic resin, a hydroxyl group-containing polymerizable unsaturated monomer is essential, and other acrylic polymerizable unsaturated monomers and / or vinyl polymerizable unsaturated monomers are used. It can be obtained by polymerizing a polymerizable unsaturated monomer by ordinary radical polymerization or the like.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer include (meth) 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like. Monoesterified product of acrylic acid and C2-8 dihydric alcohol, ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and C2-8 dihydric alcohol, N-hydroxymethyl Examples include (meth) acrylamide, allyl alcohol, and hydroxyl-containing polymerizable unsaturated monomers such as (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end, and these are used alone or in combination of two or more. can do.

  Other polymerizable unsaturated monomers copolymerized with the hydroxyl group-containing polymerizable unsaturated monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Nonyl (meth) acrylate, dodecyl (meth) acrylate (lauryl (meth) acrylate), tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate Or alkyl such as methyl cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate or the like Alkyl (meth) acrylates having an alkyl group such as cycloalkyl (meth) acrylate; aromatic ring-containing polymerizable unsaturated monomers such as benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene; vinyltrimethoxysilane, vinyl Al, such as triethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane Polymerizable unsaturated monomers having a xylyl group; perfluoroalkyl (meth) acrylates such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; polymerizable monomers having a fluorinated alkyl group such as fluoroolefin Saturated monomer; polymerizable unsaturated monomer having a photopolymerizable functional group such as maleimide group; vinyl compound such as N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate; (meth) acrylic acid, maleic acid Carboxyl group-containing polymerizable unsaturated monomers such as crotonic acid and β-carboxyethyl acrylate; (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl ( N) N-containing polymerizable unsaturated monomers such as acrylate, N, N-dimethylaminopropyl (meth) acrylamide, adducts of glycidyl (meth) acrylate and amines; glycidyl (meth) acrylate, β-methylglycidyl (meta) ) Epoxy group-containing polymerizable monomers such as acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether Saturated monomer: N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxyethyl (meth) acrylate, etho Alkoxy group-containing polymerizable unsaturated monomers such as alkoxyalkyl (meth) acrylates such as xylpropyl (meth) acrylate, polyalkylene glycol monoalkoxy (meth) acrylates such as polyethylene glycol monomethoxy (meth) acrylate; acrolein, diacetone acrylamide, Carbonyl group-containing polymerizable unsaturated monomers such as diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) These may be used alone or in combination of two or more.

  The hydroxyl group-containing acrylic resin is suitably soluble in a weak solvent. Weak solvent is a term often used in the field, and generally means a solvent with weak dissolving power and is not strictly defined, but in the classification of organic solvents according to the Industrial Safety and Health Act. The organic solvent can be a third type organic solvent. Specific examples thereof include gasoline, kerosene, coal tar naphtha (including solvent naphtha), petroleum ether, petroleum naphtha, petroleum benzine, turpentine oil, mineral spirit (mineral thinner, petrolium spirit, white spirit and mineral turpentine. These may be used singly or in combination of two or more, and contain 5% by mass or less of the first type organic solvent and the second type organic solvent in the Industrial Safety and Health Act. It may be.

  The first type organic solvent is chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,2-dichloroethylene, 1,1,2,2-tetrachloroethane, trichloroethane, carbon disulfide, and The second type organic solvent is a so-called strong solvent, such as acetone, isobutyl alcohol, isopropyl alcohol, isopentyl alcohol, ethyl alcohol, ethylene glycol monoethyl ether, ethylene. Glycol monoethyl ether acetate, ethylene glycol mono-n-butyl ether, ethylene glycol monomethyl ether, ortho-dichlorobenzene, xylene, cresol, chlorobenzene, isobutyl acetate, isopropyl acetate, isopentyl acetate, ethyl acetate, acetic acid n-butyl, acetic acid-n-propyl, acetic acid-n-pentyl, methyl acetate, cyclohexanol, cyclohexanone, 1,4-dioxane, dichloromethane, N, N-dimethylformamide, styrene, tetrachloroethylene, tetrahydrofuran, 1,1,1 -Trichloroethane, toluene, n-hexane, 1-butanol, 2-butanol, methanol, methyl isobutyl ketone, methyl ethyl ketone, methyl cyclohexanol, methyl cyclohexanone, methyl-n-butyl ketone and the like can be mentioned.

  Commercially available products may be used as the weak solvent, and specific examples thereof include “Swazole 1000”, “Swazol 1500” (manufactured by Maruzen Petroleum Co., Ltd.), “Solvesso 150”, “Solvesso 200”, “ “HAWS”, “LAWS” (above, manufactured by Shell Japan), “Essonaphtha No. 6”, “Exor D30” (trade name, manufactured by ExxonMobil Chemical), “Pegasol 3040” (trade name, manufactured by ExxonMobil Chemical) ), “A Solvent”, “Clensol”, “Ipsol 100” (manufactured by Idemitsu Kosan Co., Ltd.), “Mineral Spirit A”, “High Alom 2S”, “High Alom 2S” (above, Shin Nippon Petrochemical Co., Ltd.), “Linearene 10”, “Linearene 12” (above, manufactured by Idemitsu Petrochemical Co., Ltd.), “Rikasolve 900”, “Rikaso” Bed 910B "," Rikasorubu 1000 "(or, New Japan Chemical Co., Ltd.) and the like can be illustrated, may be used alone or in combination.

  For the preparation of the hydroxyl group-containing acrylic resin, an organic solvent other than the weak solvent can be used. Examples of such other organic solvents include hydrocarbon solvents such as n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane and cyclobutane; aromatic solvents such as toluene and xylene; ketones such as methyl isobutyl ketone Solvent: ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol; ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol Ester solvents such as monomethyl ether acetate and butyl carbitol acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone; Lumpur, isopropanol, n- butanol, sec- butanol, may be mentioned conventionally known solvents such as alcohol solvents such as isobutanol.

  The hydroxyl group-containing acrylic resin has a hydroxyl value per solid content of 5 to 80 mgKOH / g, preferably 10 to 50 mgKOH / g, and a weight average molecular weight of 5,000 to 100,000, preferably 10,000 to 50,000. It is suitable from the point of the rust prevention property of a coating film, and a weather resistance.

  In this specification, solid content means non-volatile content, means a residue obtained by removing volatile components such as water and organic solvent from a sample, and is calculated by multiplying the mass of the sample by the solid content concentration. be able to. The solid content concentration can be obtained by dividing the mass of a residue obtained by drying about 3 grams of a sample at 105 ° C. for 3 hours by the mass before drying, and may be expressed as a 100 fraction.

  The weight average molecular weight is a value obtained by converting the weight average molecular weight measured with a gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation) based on the weight average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 ml / min, detector: RI.

<Anti-rust pigment composition (B)>
In the present invention, the rust preventive pigment composition (B) is a composition characterized by containing both silica (b1) and a phosphate metal salt (b2).

<Silica (b1)>
In the present invention, the silica (b1) used in the rust preventive pigment composition (B) is a natural product even if it is a synthetic product as long as it contains silicon dioxide (SiO ₂ ) as a part of its components. It may be crystalline or amorphous. Moreover, as said silica (b1), silica type compound compounds, such as turquoise and fluorite, are also included.

  These exemplified compounds may be untreated, may be metal ion-exchanged silica into which metal ions have been introduced, or may be those whose surface has been treated with an organic substance or the like.

  Commercially available products of the silica (b1) include “Silicia 710”, “Silicia 740”, “Silicia 550”, “Aerosil R972” (all of which are manufactured by Fuji Silysia Chemical Co., Ltd.), “Mizukasil P-73”. (Manufactured by Mizusawa Chemical Co., Ltd.), “Gascil 200DF” (manufactured by Crossfield), and the like.

  Further, as an organic solvent-dispersible colloidal silica in which silica fine particles having an average particle size of about 5 to 120 nm are dispersed in an organic solvent such as alcohols, glycols, ethers, etc., the “OSCAL” series (catalyst Kasei Co., Ltd.) and “organosol” (Nissan Chemical Co., Ltd.).

  The metal ion exchange silica is silica in which metal ions are introduced into a fine porous silica carrier by ion exchange. Specific examples of metal ions include calcium ions, magnesium ions, cobalt ions, nickel ions, and the like.

  Introduction of metal ions into the silica support can be performed by stirring and mixing an aqueous solution containing the metal ions and silica.

  As calcium ion exchange silica, “SHIELDEX C303”, “SHIELDEX AC-3”, “SHIELDEX C-5” (trade names, all of which are manufactured by WR Grace & Co.) are commercially available. These commercially available products can also be used.

<Phosphate metal salt (b2)>
The phosphoric acid metal salt (b2) is a salt of at least one acid selected from phosphoric acid, phosphorous acid, and tripolyphosphoric acid containing at least magnesium as a metal.

  In other words, it is a phosphoric acid metal salt which is a salt of at least one of phosphoric acid, phosphorous acid and tripolyphosphoric acid, and is a compound containing at least magnesium.

  When the phosphoric acid metal salt (b2) contains at least magnesium as a metal, the coating composition of the present invention has an appropriate viscosity at the time of coating and has excellent coating workability, and weather resistance and rust prevention of the formed coating film It is effective in coexistence of sex.

  Examples of the phosphate metal salt (b2) include magnesium phosphate, magnesium phosphate / ammonium eutectoid, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, magnesium phosphate / calcium eutectoid, and magnesium phosphate.・ Cobalt eutectoid, Magnesium phosphate / nickel eutectoid, Magnesium phosphite, Magnesium phosphite / calcium eutectoid, Tripolyphosphate, Magnesium oxide treatment of aluminum trihydrogenphosphate, Zinc trihydrogenphosphate And the like, and the like.

  In the present invention, the antirust pigment composition (B) is characterized by containing both silica (b1) and phosphoric acid metal salt (b2). The rust prevention property of the film can be improved and the weather resistance can be good.

  In particular, the use ratio is within the range of 10/90 to 90/10, preferably 20/80 to 80/20, as the mass ratio of the former / the latter, which is suitable from the viewpoint of rust prevention and weather resistance of the coating film. Yes.

  In addition to the silica (b1) and the phosphoric acid metal salt (b2), the rust preventive pigment composition (B) includes a phosphoric acid metal salt other than a silicate metal salt and a phosphoric acid metal salt (b2), Vanadium compounds such as vanadium pentoxide, calcium vanadate, magnesium vanadate and ammonium metavanadate, calcined products of manganese oxide and vanadium oxide, calcined products of calcium phosphate and vanadium oxide, etc .: aluminum molybdate, calcium molybdate, phosphomolybdic acid Known rust preventive pigments such as aluminum, calcium carbonate, and cobalt hydroxide can be included. These rust preventive pigments can be used alone or in combination of two or more.

  Among these, examples of the metal silicate include calcium silicate, zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, aluminosilicate, borosilicate, beryllosilicate, and calcium aluminum silicate. Sodium silicate, aluminum beryllium silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, calcium silicate sodium, zirconium silicate, magnesium orthosilicate, magnesium metasilicate, magnesium calcium silicate, manganese silicate, silica Barium acid etc. are mentioned, These can be used individually or in combination of 2 or more types. Among these, metal silicate salts derived from calcium such as calcium silicate, calcium orthosilicate, and calcium metasilicate can be preferably used.

  In the present invention, when the rust preventive pigment composition (B) contains a silicate metal salt, in that case, the content is 1 to 4 based on the total mass of silica (b1) and phosphate metal salt (b2). It is suitable that it is in the range of 40% by mass, preferably 5 to 30% by mass, from the viewpoints of paint stability, finish of the obtained coating film and rust prevention.

  Examples of the phosphate metal salt other than the phosphate metal salt (b2) include a phosphate metal salt not containing magnesium.

  Specifically, for example, calcium phosphate, calcium phosphite, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate phosphate, aluminum phosphate, aluminum hydrogen phosphate; aluminum tripolyphosphate, nitric acid tripolyphosphate A tripolyphosphate metal salt in which the metal element such as aluminum aluminum is aluminum or calcium can be given.

  In the two-component polyurethane coating composition of the present invention, the reason why the anticorrosive pigment composition (B) contributes to both the antirust property and the weather resistance of the coating film is not clear, but it should be considered as follows. Can do.

  When the coating film containing the rust-preventive pigment composition (B) is placed in a corrosive environment, the silica (b1) is hydrolyzed to release the silicate ions gradually while returning the pH of the corroded area to neutral. Since it forms a precipitating salt with metal ions derived from the base such as iron ions that have been eroded and corroded, it can effectively cover exposed parts such as scratches and cut surfaces on the substrate surface. Is considered to improve.

  The phosphate metal salt (b2) releases magnesium ions and phosphate ions slowly, and magnesium ions corrode the iron and other substrate surfaces and elute hydroxide ions and phosphate ions. It is considered that metal ions existing in corrosive areas such as iron ions or magnesium ions can each form a precipitating salt and can effectively cover exposed parts such as scratches and cut surfaces on the substrate surface. .

  In the rust preventive pigment composition (B) as described above, since each component effectively and synergistically complements the action, a passive coating is formed on the corroded substrate surface for a small amount of elution. it is conceivable that. Moreover, since it is a small amount of elution, since there are few voids in the coating film formed by the elution of a rust preventive component, it can exhibit excellent weather resistance and rust resistance.

  The elution amount of the rust preventive pigment composition (B) can be known, for example, by eluting the rust preventive pigment composition (B) into an aqueous sodium chloride solution and measuring the elution amount by ICP emission spectroscopic analysis.

  More specifically, 10% by mass of a rust preventive pigment composition (B) was added to a 5% by mass sodium chloride aqueous solution, stirred at 25 ° C. for 6 hours, and allowed to stand for 24 hours to remove precipitates. The total amount of dissolved elements as measured by ICP emission spectroscopic analysis of the supernatant can be 300 μg / ml or less, preferably 50 to 200 μg / ml.

  In the present invention, the rust preventive pigment composition (B) is characterized by containing both silica (b1) and a phosphate metal salt (b2), but the content of the zinc rust preventive pigment is small. Alternatively, it can be said that one of the features is not included.

  Specifically, the content of the zinc-based anticorrosive pigment is 50% by mass or less, preferably 30% by mass or less, based on the mass of the antirust pigment composition (B), and the resin solid contained in the main component (I) It is preferably 5 parts by mass or less, preferably 3 parts by mass or less based on 100 parts by mass.

  Examples of such zinc-based anticorrosive pigments include those known in the paint field. Specific examples include zinc dust, zinc oxide, zinc phosphate, zinc phosphite, zinc orthophosphate, zinc polyphosphate, and molybdic acid. Zinc and the like can be mentioned.

  The zinc-based anticorrosive pigment as described above is a useful pigment as a non-chromium-based anticorrosive pigment, but in the present invention, if the content of this component is too large, the main component (I) and the curing agent component (II) are mixed. The viscosity increase of the composition may be so early that the so-called pot life becomes short, which makes it difficult to paint.

  In the polyurethane coating composition of the present invention, the blending amount of the rust preventive pigment composition (B) as described above is 3 to 20 on the basis of 100 parts by mass of the total resin solid content contained in the main component (I). It is suitable from the viewpoint of rust prevention and weather resistance of the two-component polyurethane coating to be in the range of 5 parts by mass, preferably 5 to 15 parts by mass.

  Moreover, it is suitable from the viewpoint of the rust prevention property of the coating film that the polyurethane coating composition of the present invention further contains a silane coupling agent.

A conventionally well-known thing can be widely used as said silane coupling agent.
For example, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, γ-ani Amino group-containing silane coupling agents such as linopropyltrimethoxysilane;
mercapto group-containing silane coupling agents such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane;
Epoxy group-containing silane cups such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane Ring agent;
Carboxy-containing silane coupling agents such as β-carboxyethylphenylbis (2-methoxyethoxy) silane and N-β- (N-carboxymethylaminoethyl) -γ-aminopropyltrimethoxysilane;
Ketiminated silane coupling agent obtained by dehydration condensation of amino group-containing silane coupling agent and various ketones; reaction product of amino group-containing silane coupling agent and epoxy group-containing silane coupling agent; mercapto group-containing silane Reaction product of coupling agent and epoxy group-containing silane coupling agent; Reaction product of amino group-containing silane coupling agent and epoxy resin; Reaction product of mercapto group-containing silane coupling agent and epoxy resin; Vinyltrimethoxysilane And vinyl group-containing silane coupling agents such as vinyltriethoxysilane and vinyltriacetoxysilane; and methacryloxy-containing silane coupling agents such as 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane. These silane coupling agents may be used alone or in combination of two or more.

  In the present invention, from the viewpoint of the storage stability of the main agent component (II) and the curing agent component (II), the amino group-containing silane coupling agent and the epoxy group-containing silane coupling agent are the main agent component (I), The isocyanate group-containing silane coupling agent is suitably contained in the curing agent component (II), and the other silane coupling agent components may be either the main component (I) or the curing agent component (II). Is preferably contained in the curing agent component (II).

  As the usage-amount of the said silane coupling agent, when a silane coupling agent is contained in main ingredient component (I), 0.1-3.5 mass% on the basis of resin solid content contained in main ingredient component (I) , Preferably in the range of 0.3 to 2.0% by mass.

  On the other hand, when the silane coupling agent is contained in the curing agent component (II), the range is 2 to 25% by mass and 3 to 15% by mass based on the active mass of the polyisocyanate compound contained in the curing agent component (II). It is suitable from a viewpoint of the rust prevention property of a coating film, and the reactivity of a hydroxyl-containing resin (A) and a polyisocyanate compound (C).

  In addition to the hydroxyl group-containing resin (A), the rust preventive pigment composition (B) and the silane coupling agent blended as necessary, the main component (I) includes a coloring pigment and an extender pigment that can be used in the paint field. , Anti-rust pigments other than the anti-rust pigment composition (B), organic solvents; modifying resins other than the hydroxyl group-containing resin (A); curing catalyst, anti-mold agent, anti-settling agent, pigment dispersant, antifoaming agent, Additives such as a coating surface adjusting agent can be blended as necessary.

  Examples of the colored pigment include organic colored pigments such as cyanine blue, cyanine green, organic red pigments such as azo and quinacridone; and inorganic colored pigments such as titanium white, titanium yellow, bengara, carbon black, and various fired pigments. Can do.

  Examples of the extender pigment include talc, clay, silica, mica, alumina, calcium carbonate, barium sulfate and the like.

  The organic solvent can be appropriately selected from the solvents exemplified in the description of the hydroxyl group-containing acrylic resin.

<Curing agent component (II)>
In the present invention, the curing agent component (II) contains a polyisocyanate compound (C).

  As this polyisocyanate compound (C), it is a compound which has two or more free isocyanate groups in 1 molecule, A conventionally well-known thing can be used without a restriction | limiting. Examples include aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, araliphatic polyisocyanate compounds, aromatic polyisocyanate compounds, and derivatives of these polyisocyanate compounds.

  Examples of the polyisocyanate compound derivative include dimer, trimer, burette, allophanate, carbodiimide, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI). ), Crude TDI and the like. These polyisocyanate compounds and derivatives thereof may be used alone or in combination of two or more.

  In addition to the polyisocyanate compound (C) and the silane coupling agent blended as necessary, the curing agent component (II) is an organic solvent that can be used in the paint field; a curing catalyst, an antifungal agent, an anti-settling agent, Additives such as an antifoaming agent and a coating surface adjusting agent can be blended as necessary.

<Two-component polyurethane coating composition>
The two-component polyurethane coating composition of the present invention is obtained by mixing the above main agent component (I) and curing agent component (II) separately stored before painting by the painter,
The use ratio is such that the equivalent ratio of the isocyanate group contained in the curing agent component (II) is 0.3 to 1.6, preferably 0.6 to 1 with respect to 1 equivalent of the hydroxyl group contained in the main agent component (I). It is suitable from the viewpoint of the weather resistance of the coating that it is adjusted to be within the range of 4.

  Further, the use ratio (mass ratio) of the main component (I) and the curing agent component (II) is generally within the range of 20/1 to 3/1, preferably 14/1 to 4/1.

  The polyurethane coating composition obtained as described above has a viscosity suitable for coating that is easy for a coating worker to paint, but preferably comprises mixing the main component (I) and the curing agent component (II). It is suitable to carry out the coating within 24 hours, preferably within 12 hours, more preferably within 3 hours.

  Further, the polyurethane coating composition of the present invention can be a weak solvent type, and the weak solvent content contained in the main component (I) or the curing agent component (II) in the storage stage (sealed state) It can be in the range of 50% by weight or more, in particular 70% by weight or more, based on the organic solvent. By being a weak solvent type, it is possible to suppress the occurrence of stigma when the coating composition of the present invention is applied on the old coating film, and has the advantage that the environmental load by coating is relatively small. .

  The two-component polyurethane coating composition of the present invention can be cured at room temperature, and the cured polyurethane film exhibits excellent performance, but may be forced-dried or heat-cured.

  As the coated surface to which the two-component polyurethane coating composition of the present invention is applied, a metal material surface subjected to a ground treatment as necessary, for example, iron, steel plate surface, galvanized surface, stainless steel surface, aluminum surface, The old paint film surface that has been painted can be mentioned, but the surface of the base material, such as concrete, mortar, slate, slate roof tiles, etc., ceramic building materials, plastics, etc. It can also be painted.

  Although the use is not particularly limited, it is suitable for metal surface coating applications such as buildings, doors of structures, handrails, and piping.

The polyurethane coating composition of the present invention can be applied by known means such as spray coating, roller coating, brush coating, flow coating, etc., after dilution to the coating viscosity as necessary, and generally 30 to 400 g / m. ² , preferably 50 to 250 g / m ² .

  The polyurethane paint composition of the present invention has both excellent rust prevention and weather resistance, and can be applied as an undercoat paint. However, depending on the condition of the object to be coated and the coating environment, a known undercoating or overcoating is known. May be performed.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples. In the following examples, “part” and “%” mean “part by mass” and “% by mass”, respectively.

Examples 1-31 and Comparative Examples 1-5
A base agent and a curing agent were produced with the composition shown in Table 1 below, and both were mixed to obtain each coating composition. Table 1 shows the equivalent ratio of isocyanate groups to 1 equivalent of hydroxyl groups contained in the main component. In Table 1, the blending amount of the acrylic resin solution is a solid content display, and the other components are the actual blending display.

(Note 1) Acrylic resin solution 1: styrene / isobutyl methacrylate / 2 ethylhexyl acrylate / hydroxyethyl methacrylate = 30/30/30/10 copolymer solution, weight average molecular weight 2,0000, hydroxyl value per solid content 43 mg KOH / g , Solid content concentration 50%, solvent mineral spirit,
(Note 2) Acrylic resin solution 2: styrene / isobutyl methacrylate / 2 ethylhexyl acrylate / hydroxyethyl methacrylate / acrylic acid = 30/35/29/5/1 copolymer solution, weight average molecular weight 2,0000, per solid content Hydroxyl value 22 mgKOH / g, solid content concentration 50%, solvent mineral spirit,
(Note 3) Polyisocyanate 1: 3/7 (mass ratio) mixture of allophanate and isocyanurate,
(Note 4) Polyisocyanate 2: 4/6 (mass ratio) mixture of allophanate and isocyanurate.

<Anti-rust pigment composition>
Rust preventive pigment compositions 1 to 20 were obtained by mixing each component with the composition shown in Table 2 below, grinding in a mortar, then heating at 150 ° C. for 3 hours, and grinding again in a mortar. Table 2 also shows the elution amount of each rust preventive pigment composition measured by the method of ICP emission spectroscopic analysis described in the specification.

(Note 5) Silica: “Silicia 710” (trade name, manufactured by Fuji Silysia Chemical Ltd.),
(Note 6) Calcium ion exchanged silica: “SHIELDEX C303” (trade name, manufactured by WR Grace & Co.),
(Note 7) Magnesium ion exchanged silica:
10 parts by weight of “Silicia 710” (trade name, silica fine particles, manufactured by Fuji Silysia Chemical Co., Ltd.) is mixed for 5 hours in 10,000 parts by weight of a magnesium chloride aqueous solution having a concentration of 5% by mass, and then filtered to obtain a solid content. The solids were taken out, washed thoroughly with water and dried to obtain magnesium ion exchanged silica.
(Note 8) Cobalt ion exchanged silica:
In the above (Note 7), cobalt ion-exchanged silica was obtained in the same manner as (Note 7) except that magnesium chloride was replaced with cobalt (II) chloride.
(Note 9) Nickel ion exchange silica:
Nickel ion-exchanged silica was obtained in the same manner as in the above (Note 7) except that magnesium chloride was changed to nickel (II) chloride.

<Performance evaluation>
Each coating composition obtained in Examples 1 to 31 and Comparative Examples 1 to 5 was evaluated by the following performance method and evaluation criteria. The results are also shown in Table 1.

(*) The pot life base agent and the curing agent were mixed and the paint state after 4 hours was observed.
○: Neither gelation nor phase separation of the paint is observed,
Δ: At least one of gelation and phase separation of paint is slightly observed,
X: At least one of gelation and phase separation of the paint is remarkably observed.
(*) Each of the curable polypropylene plates obtained by mixing the main agent and the curing agent and applying the paint immediately using a 150 μm applicator and drying in a chamber at room temperature of 23 ° C. and humidity of 50% for 7 days. The coating film of the coated plate was peeled from the polypropylene plate to obtain an isolated coating film, which was used as a test sample. Each test sample was wrapped in a 150 mesh wire net, soaked in xylene for 16 hours, taken out, rinsed thoroughly with xylene, dried at 105 ° C. for 3 hours, and the xylene insoluble fraction (%) was measured. Then, the curability was evaluated. (Xylene insoluble fraction (%) = (mass after drying sample / initial mass of sample) × 100)
○: Insoluble fraction (%) is 85% or more,
Δ: Insoluble fraction (%) is 70% or more and less than 85%,
X: Insoluble fraction (%) is less than 70%.
(*) Brush coating at a coating amount of 100 g / m ² within 30 minutes after mixing each coating composition obtained by mixing the main agent and the curing agent on the corrosion-resistant zinc phosphate-treated 0.8 mm thick SPCC steel plate. After coating and curing for 7 days at room temperature (20 ° C.), a test plate was cut with an 8 cm long cut with a cutter. The obtained test plate was tested in a 5% salt spray test apparatus at a temperature of 35 ° C. for 240 hours, and then evaluated in four stages by observing the appearance of the test plate.
A: The rust width (one side) of the cut part is less than 15 mm, and there is no abnormality in the general part.
A: The rust width (one side) of the cut part is 15 mm to 20 mm, and there is no abnormality in the general part.
Δ: The rust width (one side) of the cut part is 20 mm or less, but blisters and rust are generated in the general part.
X: The rust width (one side) of the cut part exceeds 20 mm, and blisters and rust are generated in the general part.
(*) Weather resistance After preparing a test coated plate with each coating composition by the same method as the above corrosion resistance evaluation and irradiating for 300 hours according to the accelerated weather resistance test of 7-7 (xenon lamp method) of JIS K 5600 The coated plate was visually evaluated.
A: No change in gloss or color is observed compared to the initial coating film.
○: Some changes in gloss and color are recognized compared to the initial coating film.
Δ: Changes in gloss and color are recognized compared to the initial coating film.
X: Significant changes in gloss and color compared to the initial coating film.

Claims (6)

A main component (I) containing a hydroxyl group-containing resin (A) and a rust preventive pigment composition (B) containing a hydroxyl group-containing acrylic resin having a hydroxyl value per solid content of 5 to 80 mg KOH / g, and a polyisocyanate compound (C) A two-component polyurethane coating composition obtained by mixing a curing agent component (II) containing the coating composition before coating,
The rust preventive pigment composition (B) contains both silica (b1) and phosphate metal salt (b2) as part of its components, and the phosphate metal salt (b2) contains at least magnesium as a metal. A salt of at least one acid selected from phosphoric acid, phosphorous acid, and tripolyphosphoric acid,
The rust preventive pigment composition (B) is 10% by weight of the rust preventive pigment composition (B) with respect to a 5% by weight sodium chloride aqueous solution, stirred at 25 ° C. for 6 hours, allowed to stand for 24 hours and precipitated An organic solvent-based room temperature curable two-component polyurethane coating composition characterized in that the total amount of dissolved elements measured by ICP emission spectroscopic analysis of the supernatant from which the product has been removed is 300 μg / ml or less . 2. The use ratio of silica (b1) and phosphoric acid metal salt (b2) in the antirust pigment composition (B) is in the range of 10/90 to 90/10 in terms of the former / latter mass ratio. A two-component polyurethane coating composition. Resin total solid content in which the content of the zinc-based anticorrosive pigment contained in the antirust pigment composition (B) is 50% by mass or less based on the mass of the antirust pigment composition (B) and contained in the main component (I) The two-component polyurethane coating composition according to claim 1 or 2 , wherein the content is 5 parts by mass or less based on 100 parts by mass. Amount of anticorrosive pigment composition (B) is with claim 1 in the range of 3 to 20 parts by weight based on the resin total 100 parts by weight of the solid content contained in the main agent component (I) of 3 1 2. Two-component polyurethane coating composition according to item. The two-component polyurethane coating composition according to any one of claims 1 to 4 , further comprising a silane coupling agent. 6. A coating method, wherein the object is coated with the two-component polyurethane coating composition according to any one of claims 1 to 5 .