Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

Definitions

• the present invention relates to an aqueous coating composition containing a fluorocopolymer containing a carboxylate group, a process for producing it, and a two-pack type curable aqueous coating kit using the aqueous coating composition.
• An aqueous coating material is useful as a coating material suitable for natural environmental protection since it is possible to reduce the content of an organic solvent as compared with a solvent type coating material.
• a process for producing the aqueous coating material a process to obtain a water-dispersion by emulsion polymerization of a fluorocopolymer, is known.
• a substantial amount of the emulsifier needs to be used, which causes decrease of the water resistance or weather resistance of a coating film to be obtained.
• Patent Document 1 discloses an invention relating to an aqueous coating composition. It is disclosed that the composition can be obtained by carrying out emulsion polymerization of a fluoroolefin with another monomer by using a fluorocopolymer having a hydrophilic side chain as an emulsifier.
• Patent Document 2 discloses an invention of a coating material which is a composition comprising a polymer for fluorinated coating material which contains from 4 to 30 mol % of a carboxylate-containing structure unit in which at least 30% of a carboxyl group is neutralized with ammonia or a tertiary amine, and an aqueous medium containing at least 10 vol % of a hydrophilic medium based on water.
• Patent Document 2 U.S. Pat. No. 5,447,982
• Patent Document 3 U.S. Pat. No. 5,171,804
• Patent Document 1 discloses that the amount of hydrophilic moieties gives an influence on emulsion polymerization, but it does not disclose an influence given by a carboxylate group and its amount on an aqueous coating composition at all.
• the present invention has objects to provide a composition wherein increase of the molecular weight, gelation, agglomeration, etc. are suppressed, and an excellent storage stability is performed; and a composition which forms a coating film having good water permeability/water resistance.
• the present invention provides an aqueous coating composition which comprises a fluorocopolymer containing a carboxylate group in a specific amount and an aqueous medium, and which exhibits the above performance; a process for producing the aqueous coating composition; and a two-pack type curable aqueous coating material kit.
• the present inventors have found that a composition comprising a fluorocopolymer containing a carboxylic group in a specific amount becomes a composition wherein increase of the molecular weight, gelation, agglomeration, etc. are suppressed, and an excellent storage stability is performed; and they have found that such performances are obtainable even when no organic solvent is substantially present. Further, they have found that the aqueous coating composition of the present invention forms a coating film having good water permeability/water resistance.
• the present invention provides the following.
• An aqueous coating composition which is a composition obtained by dispersing a fluorocopolymer (A) obtained by a solution polymerization method, in an aqueous medium, and which comprises the fluorocopolymer (A) which is a copolymer containing the following units (1) to (4), wherein a proportion of the repeating unit (4) is from 0.4 mol % to less than 4 mol % based on the total repeating units, and an aqueous medium, wherein an amount of an organic solvent contained in the composition is from 0 to 1 mass %:
• Unit (1) a repeating unit of a fluoroolefin
• Unit (2) a repeating unit of a vinyl monomer or an allyl monomer, and a hydroxyl group and/or a carboxyl group which may form a salt, is not bonded to the unit
• Unit (3) a repeating unit of a vinyl monomer having a hydroxyl group bonded thereto or of an allyl monomer having a hydroxyl group bonded thereto, and a carboxyl group which may form a salt, is not bonded to the unit
• Unit (4) a repeating unit of a vinyl monomer or an allyl monomer, which is also a repeating unit to which a carboxylate group in which a part may be a carboxyl group, is bonded.
• each of X 1 and X 2 is independently a hydrogen atom, a chlorine atom or a fluorine atom
• X 3 is a chlorine atom, a fluorine atom or —CY 1 Y 2 Y 3 (wherein each of Y 1 , Y 2 and Y 3 is independently a hydrogen atom, a chlorine atom or a fluorine atom);
• R a is a hydrogen atom or a methyl group
• R 1 is a C 1-12 alkyl group or a C 4-10 monovalent alicyclic hydrocarbon group
• j is 0 or 1
• k is 0 or 1
• R b is a hydrogen atom or a methyl group
• R 2 is a C 1-10 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group, m is 0 or 1, and n is 0 or 1);
• R c is a hydrogen atom or a methyl group
• R d is a hydrogen atom or a methyl group
• —COOR 3 is a carboxylate group in which a part may be a carboxyl group
• R e is a hydrogen atom or —COOR 3 (—COOR 3 has the same meaning as above)
• p is 0 or 1
• r is 0 or 1
• q is 0 or 1
• R 4 is a C 1-15 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group
• s is 0 or 1).
• the carboxylate group is a quaternary ammonium salt group of a carboxyl group.
• the aqueous medium comprises only water, or water and an organic solvent, and the amount of the organic solvent is from 0 to 0.5 mass % in the composition.
• a process for producing the aqueous coating composition as defined in any one of (1) to (4) which is characterized by carrying out sequentially a step of a copolymerization reaction in an organic solvent to obtain a fluorocopolymer (B) containing the unit (1), the unit (2), the unit (3) and a polymerized unit (4-3) derived from a monomer having a carboxyl group bonded thereto, and a step of neutralizing a part or whole of the carboxyl group in the fluorocopolymer (B) by adding a basic compound; a step of adding water; and a step of removing the organic solvent.
• R c is a hydrogen atom or a methyl group
• R d is a hydrogen atom or a methyl group
• R e is a hydrogen atom or —COOH
• p is 0 or 1
• r is 0 or 1
• q is 0 or 1
• R 4 is a C 1-15 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group, and s is 0 or 1).
• the content of an organic solvent is low, whereby a burden on an environment is small, and even if the content of the organic solvent is reduced, increase of the molecular weight of a polymer or gelation is suppressed, whereby the dispersion stability is good, and the storage stability is excellent. Further, the aqueous coating composition of the present invention provides a coating film having good water permeability/water resistance.
• the aqueous coating composition of the present invention provides a two-pack type curable aqueous coating material kit which exhibits the above performances and is easy to be handled.
• constituent repeating units constituting the polymer are abbreviated as “unit”.
• the units in the present invention may be a repeating unit (a polymerized unit) which can directly be obtained by polymerizing a monomer, or a unit which can be obtained by chemically converting the repeating unit.
• a unit represented by a formula (a1) is also shown as “a unit (a1)”.
• a monomer represented by the following formula (b1) is also shown as “a monomer (b1)”.
• the aqueous coating composition (hereinafter sometimes referred to as “a composition”) of the present invention contains a fluorocopolymer (A) as an essential component.
• the fluorocopolymer (A) is preferably contained in such a state that a part or whole of it is dispersed in the composition.
• the rest is preferably contained in a dissolved state.
• the fluorocopolymer (A) contains the following units (1) to (4), as essential units:
• Unit (1) A repeating unit of a fluoroolefin.
• Unit (2) A repeating unit of a vinyl monomer or an allyl monomer, and a hydroxyl group and/or a carboxyl group which may form a salt, is not bonded to the unit.
• Unit (3) A repeating unit of a vinyl monomer having a hydroxyl group bonded thereto or of an allyl monomer having a hydroxyl group bonded thereto, and a carboxyl group which may form a salt, is not bonded to the unit.
• Unit (4) A repeating unit of a vinyl monomer or an allyl monomer, which is also a repeating unit to which a carboxylate group in which a part may be a carboxyl group, is bonded.
• each unit may be a known unit in the fluorocopolymer to be contained in a coating composition.
• Each vinyl monomer in the units (2) to (4) is preferably a vinyl ether monomer, and the allyl monomer is preferably an allyl ether monomer.
• the fluorocopolymer (A) may be a copolymer containing only the units (1) to (4) or a copolymer containing also a unit other than the units (1) to (4) (shown as a unit (5)).
• the fluorocopolymer (A) is preferably a copolymer comprising from 40 to 60 mol % of the unit (1), from 3 to 50 mol % of the unit (2), from 4 to 30 mol % of the unit (3), from 0.4 to less than 4 mol % of the unit (4), and from 0 to 20 mol % of the unit (5) other than the units (1), (2), (3) and (4).
• the mol % is a proportion based on the total units of the fluorocopolymer (A), and the sum of the mol % of the respective units is 100 mo %.
• the unit (1) is preferably a unit represented by a formula (a1)
• the unit (2) is preferably a unit represented by a formula (a2)
• the unit (3) is preferably a unit represented by a formula (a3)
• the unit (4) is preferably a unit represented by a formula (a4-1).
• the unit (a1) is represented by the following formula (a1):
• each of X 1 and X 2 is independently a hydrogen atom, a chlorine atom or a fluorine atom
• X 3 is a chlorine atom, a fluorine atom or —CY 1 Y 2 Y 3 (wherein each of Y 1 , Y 2 and Y 3 is independently a hydrogen atom, a chlorine atom or a fluorine atom.)
• a unit obtained by polymerizing the following monomer may, for example, be mentioned.
• a fluoroethylene such as CF 2 ⁇ CF 2 , CClF ⁇ CF 2 , CHCl ⁇ CF 2 , CCl 2 ⁇ CF 2 , CClF ⁇ CClF, CHF ⁇ CCl 2 , CH 2 ⁇ CClF, CCl 2 ⁇ CClF or CH 2 ⁇ CF 2 ; or a fluoropropene such as CF 2 ClCF ⁇ CF 2 , CF 3 CCl ⁇ CF 2 , CF 3 CF ⁇ CFCl, CF 2 ClCCl ⁇ CF 2 , CF 2 ClCF ⁇ CFCl, CFCl 2 CF ⁇ CF 2 , CF 3 CCl ⁇ CClF, CF 3 CCl ⁇ CCl 2 , CCl F 2 CF ⁇ CCl 2 , CCl 3 CF ⁇ CF 2 , CF 2 ClCCl ⁇ CCl 2 , CFCl 2 CCl ⁇ CCl 2 ,
• CF 2 ⁇ CF 2 or CClF ⁇ CF 2 is preferred since the weather resistance of a coating film is excellent.
• the proportion of the unit (1) is particularly preferably from 45 to 55 mol %.
• the unit (a2) is represented by the following formula (a2).
• the unit is a unit obtained by polymerizing an alkyl vinyl ether and/or alkyl vinyl ester, an alkyl allyl ether, or an alkyl allyl ester:
• R a is a hydrogen atom or a methyl group
• R 1 is a C 1-12 alkyl group or a C 4-10 monovalent alicyclic hydrocarbon group
• j is 0 or 1
• k is 0 or 1.
• the unit (a2) may be a unit obtained by polymerizing ethyl vinyl ether, n-butyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl valerate, vinyl pivalate, etc., and among them, a unit suitable for desired physical properties (hardness, gloss, pigment-dispersibility, etc.) of a coating film, is optionally selected.
• ethyl vinyl ether, cyclohexyl vinyl ether, etc. are preferred since they have good alternating copolymerizability with a monomer for forming the unit (a1), and it is thereby easy to adjust the glass transition temperature of a resin.
• the proportion of the unit (2) is particularly preferably from 20 to 40 mol %.
• the unit (a3) is represented by the following formula (a3).
• the unit is a unit obtained by polymerizing a hydroxyl group-containing vinyl ether, a hydroxyl group-containing vinyl ester, a hydroxyl group-containing allyl ether or a hydroxyl group-containing allyl ester:
• R b is a hydrogen atom or a methyl group
• R 2 is a C 1-10 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group
• m is 0 or 1
• n is 0 or 1.
• the unit (a3) is preferably a unit obtained by polymerizing a 2-hydroxyalkyl vinyl ether, 4-hydroxybutyl vinyl ether, 1-hydroxymethyl-4-vinyloxymethyl cyclohexane or 4-hydroxybutyl vinyl ester, and a hydroxyalkyl vinyl ether is particularly preferred from the viewpoint of the polymerization property, the crosslinking property, etc.
• the proportion of the unit (a3) is preferably from 4 to 30 mol %, particularly preferably from 8 to 25 mol %.
• the proportion of the unit (a3) is in such a range, there is an advantage such that: the crosslink density can be increased, or the water resistance can be improved.
• the unit (a4-1) is represented by the following formula (a4-1):
• R c is a hydrogen atom or a methyl group
• R d is a hydrogen atom or a methyl group
• —COOR 3 is a carboxylate group in which a part may be a carboxyl group
• R 3 is a hydrogen atom or —COOR 3 (R 3 has the same meaning as above)
• p is 0 or 1
• r is 0 or 1
• q is 0 or 1
• R 4 is a C 1-15 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group
• s is 0 or 1.
• the carboxylate group is a group wherein a carboxyl group (—COOH) forms an ionic bond with a salt group, and it is preferably a quaternary ammonium salt group of a carboxyl group.
• the unit (a4-1) is preferably a unit obtained by polymerizing a terminal unsaturated carboxylic acid selected from 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3-hexenoic acid, 5-hexenoic acid, 2-heptenoic acid, 3-heptenoic acid, 6-heptenoic acid, 3-octenoic acid, 7-octenoic acid, 2-nonenoic acid, 3-nonenoic acid, 8-nonenoic acid, 9-decenoic acid, 10-undecenoic acid, 3-allyloxy propionic acid, allyloxy valeric acid, monovinyl adipate, vinyl crotonate, monovinyl succinate and maleic acid, wherein a part or whole of the carboxyl group forms a salt, or a unit obtained by polymerizing the terminal unsaturated carboxylic acid, of which a part or whole is in the form of a salt.
• —COOR 3 is a carboxylate group in which a part may be a carboxyl group. Based on the total amount of the carboxyl group and carboxylate group, which are present in the fluorocopolymer (A), the proportion of the carboxylate group is preferably at least 60 mol %, particularly preferably at least 65 mol %.
• R 3 in —COOR 3 may be optionally changed by the type of an amine used for forming the salt. Examples of the amine will be mentioned later.
• the —COOR 3 moiety is preferably —COO ⁇ ⁇ (N + HZ 1 Z 2 Z 3 ).
• N + HZ 1 Z 2 Z 3 is a quaternary ammonium, and it may be one type or two or more types.
• Each of Z 1 , Z 2 and Z 3 is independently a hydrogen atom, a C 1-4 alkyl group or a C 1-6 -hydroxyalkyl group.
• the unit (4) other than the unit (4a-1), is preferably a unit represented by the following formula (a4-2):
• —COOR f is a carboxylate group in which a part may be a carboxyl group
• —COOR g is the same group as the —COOR f or an alkoxy carbonyl group wherein the alkyl group moiety is a C 1-4 alkyl group
• R h is a hydrogen atom or a methyl group.
• unit (a4-2) a unit obtained by polymerizing a monoalkyl ester of 5-norbornene-2,3-dicarboxylic acid and its salt may be exemplified.
• the proportion of the unit (4) is from 0.4 mol % to less than 4 mol %, preferably from 0.4 to 3.9 mol %, particularly preferably from 1.4 to 3.9 mol %, especially preferably from 2.0 to 3.9 mol %.
• the proportion of the unit (4) is in the above range, the dispersibility of the fluorocopolymer (A) and the stability of the composition will improve. Further, the water resistance and water permeability of a coating film to be formed by the fluorocopolymer (A) will significantly improve.
• the unit (5) to be optionally contained in the fluorocopolymer (A) of the present invention a polymerized unit of ethylene is exemplified.
• the fluorocopolymer (A) is preferably a copolymer containing no unit (5). That is, the fluorocopolymer (A) is preferably a copolymer containing the units (1), (2), (3) and (4), or a copolymer containing the units (a1), (a2), (a3) and (a4-1).
• the particularly preferred constitution of the fluorocopolymer (A) is from 45 to 55 mol % of the unit (a1), from 14 to 45.6 mol % of the unit (a2), from 8 to 25 mol % of the unit (a3), from 1.4 to less than 4 mol % of the unit (a4-1) and/or the unit: (a4-2) and 0 mol % of the unit (a5) (that is, the unit (a5) is not present).
• the fluorocopolymer (A) is a copolymer obtained by solution polymerization.
• a method of solution polymerization is described in the explanation of “PROCESS FOR PRODUCING AQUEOUS COATING COMPOSITION”. It is disadvantageous to obtain the fluorocopolymer (A) and the fluorocopolymer (B) of the present invention by emulsion polymerization, since it is thereby necessary to heavily use an emulsifier.
• the fluorocopolymer (A) obtained by solution polymerization when it is dispersed in water as applied in the form of a coating composition, its dispersed particles will easily be fused to each other, and the copolymer thus has an advantage of forming a uniform film.
• water-dispersed particles obtained by emulsion polymerization will hardly be fused to each other, whereby it is difficult to form a uniform film.
• the fluorocopolymer (A) is preferably from 10 to 100 mass %, more preferably from 55 to 100 mass %, based on the total mass of the synthetic resin contained in the aqueous coating composition. 100% means that another synthetic resin (C) to be described later, is not contained.
• the proportion of the fluorocopolymer (A) is at least 55 mass %, it is possible to obtain an aqueous coating composition excellent in weather resistance.
• the number average molecular weight of the fluorocopolymer (A) is preferably in a range of from 3,000 to 200,000.
• Mw/Mn molecular weight distribution
• the performance of the present invention will be obtained, and especially, gelation will be prevented, whereby the stability will be high.
• the aqueous coating composition of the present invention contains an aqueous medium.
• the aqueous medium is a medium composed of only water or of water and a small amount of an organic solvent.
• the content of the organic solvent is from 0 to 1 mass % based on the total mass of the composition. 0 Mass % means no organic solvent is contained, or even if it is contained, the amount is lower than the detection limit.
• the upper limit of the content of the organic solvent is 1 mass %, preferably 0.5 mass %, especially preferably 0.3 mass %, in the composition. Since the fluorocopolymer (A) of the present invention is excellent in stability in the aqueous medium, without incorporating or incorporating a small amount of the organic solvent, the good stability is secured for a long period of time.
• the organic solvent is not necessarily optionally added.
• the case where the organic solvent is contained in the composition may be a case where the organic solvent used in a polymerization step of a fluorocopolymer (B) to be described later, remains.
• the organic solvent is preferably a water-soluble organic solvent, particularly preferably acetone, methyl ethyl ketone, ethanol, methanol or the like.
• the aqueous coating composition of the present invention may contain another component other than the fluorocopolymer (A).
• Such another component may be a synthetic resin (C) other than the fluorocopolymer (A).
• the synthetic resin (C) may be dispersed or dissolved in water together with the fluorocopolymer (A).
• the synthetic resin (C) may be a synthetic resin of a fluorine type, a phenol type, an alkyd type, a melamine type, a urea type, a vinyl type, an epoxy type, a polyester type, a polyurethane type, an acryl type or the like.
• the synthetic resin (C) preferably includes a fluorine type synthetic resin.
• the fluorine type synthetic resin may be a fluorocopolymer described in Japanese Patent No. 2,955,336 containing, as essential constituents, a polymerized unit derived from a fluoroolefin and a polymerized unit derived from a macromonomer having a hydrophilic moiety.
• the hydrophilic moiety is a moiety having a hydrophilic group, a moiety having a hydrophilic bond, or a moiety made of their combination.
• the macromonomer is a low molecular weight polymer or oligomer having a radical-polymerizable unsaturated group at one terminal.
• the synthetic resin (C) preferably includes an acrylic type synthetic resin from the viewpoint of weather resistance.
• the amount is preferably from more than 0 to 20 mass %, more preferably from 10 to 20 mass %, in the aqueous coating composition.
• the synthetic resin (C) is to be incorporated, after a composition containing the fluorocopolymer (A) is prepared, it is preferred to add the synthetic resin (C) thereto, followed by stirring to have it contained in the composition.
• the solid content concentration of the synthetic resin (C) is preferably from 3 to 50 mass %, more preferably from 30 to 50 mass %.
• the aqueous coating composition of the present invention preferably optionally contain an additive such as a coalescent, a leveling agent, a thickener, an ultraviolet-absorber, a light stabilizer or an antifoaming agent.
• an additive such as a coalescent, a leveling agent, a thickener, an ultraviolet-absorber, a light stabilizer or an antifoaming agent.
• the coalescent may, for example, be diethylene glycol monoethyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol mono(2-methylpropanoate) or diethylene glycol diethyl ether.
• the leveling agent may, for example, be preferably a polyether-modified polydimethylsiloxane or a polyether-modified siloxane.
• the thickener may, for example, be preferably a polyurethane type associative thickener.
• the ultraviolet absorber it is possible to use various known ones.
• the ultraviolet absorber suitable for use for top coating as a transparent coating material may, for example, be a salicylate such as methyl salicylate, phenyl salicylate, cresyl salicylate or benzyl salicylate; a benzophenone such as 2-hydroxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-5-chlorobenzophenone, 2-aminobenzophenone or a high-molecular-weight-modified product sold as T-57 by ADEKA ARGUS; a benzotriazole such as 2-(2′-hydroxy-5′-t-butylphenyl)benzotriazole, 2-(2′-hydroxy-5′-t-butylphenyl-5-chlorobenzotriazole, 2-(2′-hydroxy-5′-methoxyphenyl)benzotriazole, 2-(2′-hydroxy-3
• the ultraviolet-absorber is used preferably within a range of from 0.1 to 15 parts by mass, more preferably within a range of from 0.1 to 5 parts by mass, per 100 parts by mass of the solid content concentration of the synthetic resin. If the amount of the ultraviolet absorber is too small, no adequate effect of improvement of light resistance is obtainable, and if it is too large, the effect tends to be saturated, such being not satisfactory.
• the light stabilizer may, for example, be a light stabilizer of a hindered amine type, such as MARK LA57, 62, 63, 67 or 68 manufactured by ADEKA ARGUS, or TINUVIN 622LD manufactured by CIBA GEIGY. They may be used alone or as a mixture of two or more types of them in combination with an ultraviolet-absorber.
• a hindered amine type such as MARK LA57, 62, 63, 67 or 68 manufactured by ADEKA ARGUS, or TINUVIN 622LD manufactured by CIBA GEIGY.
• the antifoaming agent may be a fatty acid salt, a fatty alcohol sulfate, a liquid fatty oil sulfuric acid ester, a sulfate of an aliphatic amine or an aliphatic amide, an aliphatic alcohol phosphoric acid ester, a sulfonate of a dibasic fatty acid ester, a fatty acid amide sulfonate, an alkylallyl sulfonate, a naphthalene sulfonate of a formalin condensate, a polyoxyethylene alkyl ether, a polyoxyethylene alkylphenol ether, a polyoxyethylene alkyl ester, a sorbitan alkyl ester, a polyoxyethylene sorbitan alkyl ester, an acrylic polymer, a silicone mixed acrylic polymer, a vinyl type polymer or a polysiloxane compound.
• an inorganic or organic flatting agent of common use may be added.
• a colorant such as a commercially available organic pigment, inorganic pigment, organic dye, or a composite pigment or dye of them, may be dispersed or added/mixed.
• a stabilizer such as an emulsifier may be added within a range where the water resistance and the weather resistance of the coating film are not deteriorated.
• the emulsifier is preferably an anionic emulsifier or nonionic emulsifier, or they may be used in combination.
• the nonionic emulsifier is preferably an alkylphenol ethylene oxide adduct, a fatty alcohol ethylene oxide adduct or a block copolymer of ethylene oxide and propylene oxide.
• the amount of the nonionic emulsifier to be added may be suitably selected, and it is preferably from 0 to 3 parts by weight per 100 parts by mass of the solid content of the synthetic resin.
• the anionic emulsifier is preferably an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, a higher fatty acid salt, an alkylsulfuric acid ester salt, an alkyl ether sulfuric acid ester salt or a phosphoric acid ester salt.
• the amount of the anionic emulsifier to be added may also be suitably selected, and it is preferably from 0 to 1 part by weight per 100 parts by mass of the solid content of the synthetic resin.
• the timing to add the emulsifier is preferably after a step of adding water, which is described later.
• the aqueous coating composition of the present invention is preferably produced by carrying out sequentially a step of neutralizing a part or whole of the carboxyl group in the fluorocopolymer (B) by adding a basic compound to the fluorocopolymer (B); a step of adding water; and a step of removing the organic solvent.
• the fluorocopolymer (B) is a copolymer having the unit (1), the unit (2), the unit (3), the unit (4-3), and optionally, the unit (5).
• the fluorocopolymer (B) is preferably a copolymer having the unit (a1), the unit (a2), the unit (a3), the unit (a4-3), and optionally, the unit (a5).
• the unit (4-3) is a unit having a carboxyl group bonded thereto, and the carboxyl group does not form a salt.
• the preferred unit (4-3) is represented by the following formula (a4-3).
• the proportion of each unit in the fluorocopolymer (B) is preferably from 40 to 60 mol % of the unit (1), from 3 to 50 mol % of the unit (2), from 4 to 30 mol % of the unit (3), from 0.4 to less than 4 mol % of the unit (a4-3), and from 0 to 20 mol % of the unit (5).
• the proportion of each unit is usually maintained when the fluorocopolymer (B) is obtained by the above production process, and the proportion of the unit (4-3) is the same as the proportion of the unit (4):
• R a is a hydrogen atom or a methyl group
• R d is a hydrogen atom or a methyl group
• R e is a hydrogen atom or —COOH
• p is 0 or 1
• r is 0 or 1
• q is 0 or 1
• R 4 is a C 1-15 alkylene group or a C 4-10 divalent alicyclic hydrocarbon group, and s is 0 or 1.
• unit (4) other than the above may be a unit represented by the following formula (a4-4):
• R g is EL hydrogen atom or a C 1-4 alkyl group
• R h is a hydrogen atom or a methyl group.
• the fluorocopolymer (B) is obtained by a copolymerization reaction in an organic solvent.
• the copolymerization reaction is preferably carried out by copolymerizing a fluoroolefin (B1), a vinyl monomer or allyl monomer (B2), a vinyl monomer having a hydroxyl group bonded thereto or allyl monomer having a hydroxyl group bonded thereto (B3), and a vinyl monomer or allyl monomer having a carboxyl group bonded thereto (B4).
• another monomer (B5) may be used for the copolymerization reaction.
• An example of producing the fluorocopolymer (B) may be an example of obtaining it by copolymerizing a monomer represented by the following formula (b1), a monomer represented by the following formula (b2), a monomer represented by the following formula (b3), a monomer represented by the following formula (b4-1) and an optional another monomer, in an organic solvent. Further, when it is desired to obtain the unit (4-2), it is preferred to use a monomer represented by the following formula (b4-2).
• symbols in these formulae have the same meanings as above:
• the copolymerization is carried out in such a manner that in the coexistence or absence of a polymerization catalyst, a polymerization initiating source such as a polymerization initiator or ionizing radiation is acted in the presence of a basic compound.
• a polymerization initiating source such as a polymerization initiator or ionizing radiation
• the polymerization initiator may be a peroxyester type peroxide such as t-butylperoxy acetate, a dialkylperoxy dicarbonate such as diisopropyl peroxydicarbonate, benzoyl peroxide or azobisisobutyronitrile.
• the basic compound may be selected from a wide range including an organic basic compound and an inorganic basic compound.
• the organic basic compound is preferably an alkylamine such as triethylamine or dimethylaminoethanol, or an alkylphosphine such as triethylphosphine.
• the inorganic basic compound is preferably a hydrotalcite, or a carbonate, hydroxide or oxide of an alkali metal or an alkali earth metal, such as potassium carbonate, potassium hydroxide, sodium hydroxide, magnesium hydroxide, aluminum hydroxide, magnesium oxide or aluminum oxide.
• the hydrotalcite is preferably a double salt of magnesium and aluminum.
• the amount of the polymerization initiator may suitably be changed depending on the type or the copolymerization reaction condition, but usually, it is from 0.05 to 1.5 mass %, preferably from 0.1 to 0.5 mass %, based on the total amount of monomers which should be copolymerized.
• the amount of the basic compound to be used is preferably from 0.01 to 5 mass %, more preferably from 0.1 to 3 mass %, based on the total amount of monomers which should be copolymerized.
• the polymerization solvent is preferably an alcohol, an ester, a ketone, a saturated halogenated hydrocarbon containing at least one fluorine atom or an aromatic hydrocarbon such as xylene, particularly preferably a water-soluble organic solvent, especially preferably acetone, methyl ethyl ketone, ethanol or methanol.
• the reaction temperature of the copolymerization reaction is preferably from 10° C. to 90° C., more preferably from 35 to 70° C. Further, the reaction pressure is preferably from 0 to 100 kg/cm 2 ⁇ G, more preferably from 1 to 50 kg/cm 2 ⁇ G.
• the intrinsic viscosity of the fluorocopolymer (B) is preferably from 0.05 to 2.0 dL/g, more preferably from 0.05 to 1.00 dL/g.
• the number average molecular weight of the fluorocopolymer (B) is preferably in a range of from 3,000 to 200,000. BY adjusting the molecular weight in such a range, there will be an advantage such that the weather resistance, coating property, appearance, etc., of the coating film will improve.
• the step for neutralization is a step of neutralizing a part or whole of the carboxyl group in the fluorocopolymer (B) by adding a basic compound to an organic solvent solution of the fluorocopolymer (B) obtained by carrying out solution polymerization, thereby to form a carboxylate group.
• the step for neutralization is more preferably carried out by adding a basic compound or an aqueous solution of a basic compound to an organic solvent having the fluorocopolymer (B) dissolved therein, while stirring at room temperature for several tens minutes.
• the amount of the basic compound may suitably be changed depending on the amount of the carboxylic group desired to be changed to the salt group.
• a step of adding water is carried out.
• the next step of adding water may or may not be carried out.
• the aqueous solution of a basic compound for the step for neutralization and to carry out the step of adding water.
• the amount of water is preferably an amount so that the solid concentration of the fluorocopolymer (B) becomes from 3 to 50 mass %, more preferably an amount so that the solid concentration becomes from 20 to 45 mass %.
• the basic compound to be used for the step for neutralization is preferably selected from compounds having a boiling point of at most 200° C. since the basic compound will then scarcely remain in the coating film.
• the basic compound may, for example, be ammonia, a primary, secondary or tertiary amine such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine or dibutylamine; an alkanolamine such as monoisopropanolamine, dimethylaminoethanol or diethylaminoethanol, or methyldiethanolamine; a diamine such as ethylenediamine, propylenediamine, tetramethylenediamine or hexamethylenediamine; an alkyleneimine such as ethyleneimine or propyleneimine; or pyridine such as piperazine, morpholine or pyrazine.
• a primary, secondary or tertiary amine such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine
• the basic compound is preferably an alkylamine, an alkanolamine or a diamine.
• the organic solvent is removed. Accordingly, it is possible to obtain the aqueous coating composition of the present invention having at most 1 mass % of the organic solvent based on the total mass. Removing the solvent can be carried out by distillation under reduced pressure.
• the two-pack type curable aqueous coating material kit of the present invention comprises the aqueous coating composition of the present invention and a curing agent, independently.
• the two-pack type curable aqueous coating material kit of the present invention is used after the aqueous coating composition and the curing agent are mixed at the time of use.
• a coating film By selecting the curing agent, it becomes possible to carry out crosslinking by drying at room temperature, and it is possible to form a coating film by applying the aqueous coating composition and the curing agent.
• a coating film When heating is needed for crosslinking, a coating film may be formed by heating and baking.
• the curing agent is a water-soluble or water-dispersible curing agent having a functional group reactive with a hydroxyl group or a carboxyl group.
• the curing agent may be an isocyanate compound, a melamine resin, a phenol resin, a xylene resin or a toluene resin.
• an isocyanate compound is preferred since it is easy to obtain a coating film excellent in weather resistance and mechanical property.
• the isocyanate compound is preferably one mechanically dispersed in water or a self-emulsifiable polyisocyanate compound.
• the self-emulsifiable polyisocyanate compound is a compound which can be emulsified and dispersed in water without an emulsifier.
• the polyisocyanate compound which is mechanically dispersed in water may be an aliphatic polyisocyanate such as hexamethylene diisocyanate; an aromatic polyisocyanate such as m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, naphthalene-1,5-diisocyanate or 4,4′-diisocyanate-3,3′-dimethyldiphenyl; an alicyclic polyisocyanate such as bis-(isocyanatecyclohexyl)methane or isophorone diisocyanate; a crude polyisocyanate such as crude tolylene diisocyanate or crude diphenylmethane diisocyanate; or a modified polyisocyanate such as carbodiimide-modified diphenylmethane diisocyanate, polyol-modified di
• Such a polyisocyanate is one in a form of a dimer or trimer of a burette type, an isocyanurate ring type or an uretodione type, or a blocked polyisocyanate wherein an isocyanate group is reacted with a blocking agent.
• the blocking agent may be an alcohol, a phenol, a caprolactam, an oxime or an active methylene compound.
• Such polyisocyanates may be used in combination as a mixture of two or more of them.
• Such a polyisocyanate is used as one mechanically dispersed in water, and by adding an emulsifier at the time of such dispersion, it is possible to obtain a more stable dispersion.
• the polyisocyanate to be mechanically dispersed in water is preferably one having relatively low viscosity.
• the emulsifier to be used any known one may be used without any particularly limitation, but one having ionicity, particularly one having an active hydrogen atom, is not preferred, since it undergoes a reaction at the time of dispersion, whereby it becomes thickened, or the dispersibility decreases.
• a blocked polyisocyanate will not usually be cured unless the temperature is at least 140° C., whereby when curing is desired to be carried out at a lower temperature, it is preferred to use a polyisocyanate which is not blocked.
• the self-emulsifiable polyisocyanate compound may, for example, be a prepolymer obtained by reacting a hydrophilic polyoxyalkylene with the polyisocyanate as described above.
• the hydrophilic polyoxyalkylene used for the reaction is preferably one having at least one isocyanate reactive group and a molecular weight in a range of from 200 to 4,000.
• it is a polyoxyalkylene polyol or polyoxyalkylene monool having a molecular weight in a range of from 300 to 1,500.
• the oxyalkylene chain in a polyoxyalkylene is preferably one such that whole or most of it is an oxyethylene group.
• Such a reaction of a polyisocyanate with a polyoxyalkylene glycol can be carried out in the presence of a catalyst such as a tertiary amine, an alkyl-substituted ethyleneimine, a tertiary alkylphosphine, a metal alkyl acetonate or an organic metal salt, and if necessary, in the presence of a promoter, at a temperature of at most 100° C. Further, with respect to the reaction, it is suitable to adjust the amount of the remaining isocyanate group to be from 10 to 24 mass %, preferably from 15 to 22 mass %.
• the melamine resin may be a melamine resin which is alkyl-etherified such as methyl-etherified, butyl-etherified or isobutyl-etherified, and it is preferably a melamine resin having at least a part of it is methyl-etherified from the viewpoint of water-solubility.
• the mass ratio of the aqueous coating composition of the present invention to the curing agent, in the two-pack type curable aqueous coating material kit is preferably 50 to 95 mass %:5 to 50 mass %, more preferably 75 to 95 mass %:5 to 25 mass %, in a nonvolatile composition.
• Examples 1 to 7 and Examples 10 to 15 are Examples of the present invention
• Examples 8 and 11 are Reference Examples of the present invention
• Comparative Examples 1 to 8 are Comparative Examples of the present invention.
• the fluorocopolymer constituting the varnish contained about 3 mol % of a unit derived from UDA.
• KYOWARD 500SH is an acid absorbent (an inorganic basic compound) manufactured by Kyowa Chemical Industry Co., Ltd.
• (a1) represents mol % of a unit derived from CTFE
• (a2) the total mol % of a unit derived from EVE and a unit derived from CHVE, (a3) mol % of a unit derived from HBVE, (a4)-a mol % of a unit derived from UDA, MA or CA having no carboxyl group neutralized, and (a4)-b mol % of a unit derived from UDA, MA or Ca wherein a carboxyl group is neutralized to form a carboxylate group.
• hydroxyl value in Table 1 is represented by a value of “the molar ratio of HBVE used” ⁇ 5.
• the structural unit ratio of a synthetic resin in the aqueous solution was represented by a value obtained by calculating the raw material ratio (parts by weight) at the time of polymerization by mol.
• the ratios of (a4)-a and (a4)-b represented by values obtained by calculation from the acid value before neutralization and the amount of triethylamine required for the neutralization.
• An aqueous liquid of Synthesis Example 2 was obtained in the same manner as in Synthesis Example 1 except that the monomer amounts, the solvent amounts, the types and amounts of other additives and the amount of triethylamine used were changed to the amounts shown in is Table 1, 50 mass % of EtOH used as a solvent after the polymerization, was substituted with a solvent, MEK and in distillation of the solvents, the remained solvents were distilled under reduced pressure until their total amount became 15 parts by mass of the solid content of the fluorocopolymer.
• Aqueous liquids of Synthesis Examples 3, 4, 6 and 9 were obtained in the same manner as in Synthesis Example 1 except that the monomer amounts, the solvent amounts, the types and amounts of other additives, and the amount of triethylamine used were changed to the amounts shown in Table 1.
• Aqueous liquids of Synthesis Examples 5 and 8 were obtained in the same manner as in Synthesis Example 1 except that the monomer amounts, the solvent amounts, the types and amounts of other additives, and the amount of triethylamine used were changed to the amounts shown in Table 1, and in distillation of the solvents, the remained solvents were distilled under reduced pressure until their total amount became 15 parts by mass of the solid of the fluorocopolymer.
• An aqueous liquid of Synthesis Example 7 was obtained in the same manner as in Synthesis Example 1 except that the monomer amounts, the solvent amounts, the types and amounts of other additives, and the amount of triethylamine used were changed to the amounts shown in Table 1, and about 50 mass % of EtOH used as a solvent after the polymerization, was substituted with a solvent, MEK.
• the pressure at the time when the temperature reached 50° C. was 0.3 MPa.
• a 50 mass % xylene solution of tertiary butylperoxypivalate By adding 3.0 parts of a 50 mass % xylene solution of tertiary butylperoxypivalate, the reaction was started. After the initiation of polymerization, 343 parts of CTFE, 64 parts of EVE, 111 parts of CHVE, 106 parts of HBVE and 17 parts of a 50 mass % xylene solution of tertiary butylperoxypivalate were continuously added over about 8 hours. After the completion of continuous addition, stirring was continued for 16 hours at 50° C. After cooling and purging, 0.1 part of hydroquinone monomethyl ether was added, followed by filtration to obtain a varnish of a fluorocopolymer having 59.5 mass % of a solid content.
• the fluorocopolymer constituting the varnish contained about 3 mol % of a unit derived from UDA.
• the unit ratio (mol %) of the synthetic resin in the aqueous liquid of Synthesis Example 9, which was obtained in the same manner as in each of Synthesis Examples 1 to 8, was such that (a1):(a2):(a3):(a4)-a:(a4)-b 50:30:17:0.9:2.1.
• the Mn change rate represents a value obtained by dividing the value of the molecular weight Mn after maintaining at 50° C., by the initial Mn (shown in Table 1).
• An increase of Mn means gelation or a sign of gelation.
• the coating material was directly applied by spraying on a slate board having no undercoating material applied thereon, followed by drying at room temperature for 2 weeks as above, and then, the water permeability was evaluated.
• Examples 8 and 11 are Examples wherein the amount of the remaining organic solvents exceeds 1 mass %, and they are Reference Examples.
• Table 3 The names of the respective additives in Table 3 represents the following compounds, respectively. Further, the numerical values in Table 3 are parts by mass unless otherwise specified.
• Bayhydur 3100 A water-dispersible polyisocyanate, manufactured by Sumika Bayer Urethane Co., Ltd.
• BYK348 A leveling agent (polyether-modified polydimethylsiloxane), manufactured by BYK.
• BYK080 An antifoaming agent (a silicon type antifoaming agent), manufactured by BYK.
• SANOL LS765 A light stabilizer, manufactured by Sankyo.
• TINUVIN 1130 An ultraviolet absorber (a condensate with methyl-3-(3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl)propionate-polyethylene glycol (molecular amount 300)), manufactured by CIBA GEIGY.
• Example 7 to 13 and Comparative Examples 5 and 6 The test specimen in each of Examples 7 to 13 and Comparative Examples 5 and 6 was immersed in deionized water at room temperature for 2 weeks, and its appearance change was observed. The results are shown in Table 3. Blistering in the evaluation results represents a state such that air bubbles are formed between the coating film and the substrate, whereby the appearance is deteriorated.
• the coating material was blended as shown in Table 4, and it was applied on an aluminum plate by using a film applicator so that a dried coating film would have a thickness of 40 ⁇ m, followed by drying at 80° C. for 1 hour to obtain a test specimen.
• the evaluation of its gloss and weather resistance was carried out. The results are shown in Table 4.
• X indicates one wherein its gloss is significantly deteriorated after 1,000 hours of QUV test, and ⁇ indicates one wherein no substantial deterioration is observed in its gloss.
• Table 4 The names of the respective additives in Table 4 are the same as in Table 3 except for ones shown below. Further, the numerical values in Table 4 are parts by mass unless otherwise specified.
• BASONAT HW100 A water-dispersible isocyanate, manufactured by BASF.
• the aqueous coating composition of the present invention has a low content of an organic solvent, whereby a burden on an environment is small. Further, an increase of the molecular weight and gelation of the polymer are suppressed, and the dispersion stability is excellent, whereby the composition is suited for providing a coating film which is excellent in storage stability and which has good water permeability/water resistance. Therefore, it is industrially very useful. Further, by using the composition, it is possible to provide a two-pack curable aqueous coating material kit which exhibits the above performances and which is easily handled.

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