EP4288471A1 - Water-dispersible polyisocyanate composition, method for producing composition, water-based curable composition, water-based paint, and article - Google Patents

Water-dispersible polyisocyanate composition, method for producing composition, water-based curable composition, water-based paint, and article

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Publication number
EP4288471A1
EP4288471A1 EP21923652.8A EP21923652A EP4288471A1 EP 4288471 A1 EP4288471 A1 EP 4288471A1 EP 21923652 A EP21923652 A EP 21923652A EP 4288471 A1 EP4288471 A1 EP 4288471A1
Authority
EP
European Patent Office
Prior art keywords
water
acrylic polymer
group
acrylic
mol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP21923652.8A
Other languages
German (de)
French (fr)
Inventor
Soichiro Omizu
Kai Qian
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DIC Corp
Original Assignee
DIC Corp
Dainippon Ink and Chemicals Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DIC Corp, Dainippon Ink and Chemicals Co Ltd filed Critical DIC Corp
Publication of EP4288471A1 publication Critical patent/EP4288471A1/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
    • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
    • C08G18/622—Polymers of esters of alpha-beta ethylenically unsaturated carboxylic acids
    • C08G18/6225—Polymers of esters of acrylic or methacrylic acid
    • C08G18/6229—Polymers of hydroxy groups containing esters of acrylic or methacrylic acid with aliphatic polyalcohols
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
    • C08G18/78—Nitrogen
    • C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
    • C08G18/791—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups
    • C08G18/792—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates

Definitions

  • Embodiments of the present invention relate to a water-dispersible polyisocyanate composition, a method for producing the composition, a water-based curable composition, a water-based paint, and an article.
  • Patent Literatures 1 and 2 disclose water-dispersible polyisocyanate compositions containing a polyisocyanate and a nonionic group-containing vinyl polymer. However, even these isocyanate compositions disadvantageously have short pot lives as two-component urethane coatings.
  • One aspect of the present invention is directed to providing a water-dispersible polyisocyanate composition that contains a hydrophobic polyisocyanate (A) and an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group, in which the acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate, the acrylic polymer (b) contains an acrylic polymer (b1) and an acrylic polymer (b2) , the acrylic polymer (b1) is derived from a monomer raw material containing 11 mol%or more and 35 mol%or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group, and the acrylic polymer (b2) is derived from a monomer raw material containing 2 mol%or more and less than 11 mol%of the acrylic monomer (x) .
  • the water-dispersible polyisocyanate composition according to an embodiment of the present invention provides a long pot life after mixing two components and excellent appearance of a coating film to be formed and thus can be suitably used in various paints for, for example, interiors and exteriors of automobiles, automobile repairs, plastics, industrial machinery, building materials, and woodworking.
  • a water-dispersible polyisocyanate composition contains a hydrophobic polyisocyanate (A) and an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group, in which the acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate, the acrylic polymer (b) contains an acrylic polymer (bl) and an acrylic polymer (b2) , the acrylic polymer (b1) is derived from a monomer raw material containing 11 mol%or more and 35 mol%or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group, and the acrylic polymer (b2) is derived from a monomer raw material containing 2 mol%or more and less than 11 mol%of the acrylic monomer (x) .
  • the hydrophobic polyisocyanate (A) has no hydrophilic group.
  • examples of the hydrophobic polyisocyanate (A) include aliphatic diisocyanates, such as 1, 4-tetramethylene diisocyanate, ethyl 2, 6-diisocyanatohexanoate, 1, 6-hexamethylene diisocyanate, 1, 12-dodecamethylene diisocyanate, and 2, 2, 4-or 2, 4, 4-trimethylhexamethylene diisocyanate; aliphatic triisocyanates, such as 1, 3, 6-hexamethylene triisocyanate, 1, 8-diisocyanato-4- (isocyanatomethyl) octane, and 2-isocyanatoethyl (2, 6-diisocyanato) hexanoate; alicyclic diisocyanates, such as 1, 3-bis (isocyanatomethylcyclohexane) , 1, 4-bis (isocyanatomethylcyclohexane
  • hydrophobic polyisocyanates (A) aliphatic or alicyclic diisocyanates or triisocyanates, aralkylene diisocyanates, and polyisocyanates derived therefrom are preferred in view of the stability of isocyanate groups in water and the weatherability of a coating film formed from a paint containing the water-dispersible polyisocyanate composition.
  • polyisocyanates having three or more functionalities such as isocyanurate-type polyisocyanates, polyisocyanates having a biuret structure, polyisocyanates having a uretdione structure, polyisocyanates having an allophanate structure, and polyisocyanates formed by the reaction of diisocyanates and trihydric or higher polyhydric alcohols, are preferred in order to prepare a water-based curable composition excellent in weatherability and durability.
  • a hydrophilic group-containing polyisocyanate may be used in combination with the hydrophobic polyisocyanate (A) as long as the stability of the water-dispersible polyisocyanate composition according to an embodiment of the present invention is not impaired.
  • the acrylic polymer (B) has an alkoxy group end-capped polyoxyalkylene group.
  • the polyoxyalkylene group can be easily introduced by the use of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group as the monomer raw material for the acrylic polymer (b) .
  • polyoxyalkylene group examples include a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, polyoxyalkylene groups formed by random or block copolymerization of different oxyalkylenes, and polyoxyalkylene groups formed by ring-opening polymerization of dioxolane.
  • polyoxyalkylene groups a polyoxyalkylene group containing an oxyethylene unit as an essential structural unit is preferred because water dispersibility is further improved.
  • the polyoxyalkylene group preferably has 12 to 30 oxyalkylene group repeat units because the water dispersibility and the pot life are further improved.
  • terminal alkoxy group examples include lower alkoxy groups, such as a methoxy group, an ethoxy group, and a butoxy group.
  • the acrylic polymer (b) contains the acrylic polymer (b1) and the acrylic polymer (b2) . This provides excellent pot life after mixing two components.
  • the monomer raw material for the acrylic polymer (b1) contains 11 mol%or more and 35 mol%or less, preferably 12 mol%or more and 24 mol or less of the acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group because a longer pot life is achieved.
  • the monomer raw material for the acrylic polymer (b2) contains 2 mol%or more and less than 11 mol%, preferably 5 mol%or more and 10 mol%or less of the acrylic monomer (x) because a longer pot life is achieved.
  • acrylic monomer (x) examples include methoxy poly (ethylene glycol) (meth) acrylate, ethoxy poly (ethylene glycol) (meth) acrylate, propoxy poly (ethylene glycol) (meth) acrylate, butoxy poly (ethylene glycol) (meth) acrylate, phenoxy poly (ethylene glycol) (meth) acrylate, methoxy poly (propylene glycol) (meth) acrylate, ethoxy poly (propylene glycol) (meth) acrylate, propoxy poly (propylene glycol) (meth) acrylate, butoxypoly (propylene glycol) (meth) acrylate, phenoxy poly (propylene glycol) (meth) acrylate, methoxy poly (butylene glycol) (meth) acrylate, ethoxy poly (butylene glycol) (meth) acrylate, propoxy poly (butylene glycol) (meth) acrylate, butoxy poly (butylene glycol)
  • the acrylic polymer (B) is a reaction product of the acrylic polymer (b) and the hydrophobic polyisocyanate and is easily prepared by introducing an active hydrogen-containing group into the acrylic polymer (b1) and/or the acrylic polymer (b2) andallowingthe acrylicpolymer (b1) and/or the acrylicpolymer (b2) to react with the hydrophobic polyisocyanate.
  • the active hydrogen-containing group can be easily introduced into the acrylic polymer by the use of an unsaturated monomer having an active hydrogen-containing group as a monomer raw material for the acrylic polymer (b1) and/or the acrylic polymer (b2) .
  • Examples of the unsaturated monomer having an active hydrogen-containing group include hydroxy group-containing unsaturated monomers, carboxy group-containing unsaturated monomers, amino group-containing unsaturated monomers, and active methylene group-containing unsaturated monomers. Hydroxy group-containing unsaturated monomers are preferred. These unsaturated monomers having active hydrogen-containing groups may be used alone or in combination of two or more.
  • Examples of such a hydroxy group-containing unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxy-n-butyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-n-butyl (meth) acrylate, 3-hydroxy-n-butyl (meth) acrylate, 1, 4-cyclohexanedimethanol mono (meth) acrylate, glycerol mono (meth) acrylate, poly (ethylene glycol) mono (meth) acrylate, poly (propylene glycol) mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl 2-hydroxyethyl phthalate, and lactone-modified (meth) acrylate having a terminal hydroxy group.
  • These hydroxy group-containing unsaturated monomers may be used alone or in combination of
  • an unsaturated monomer containing a hydrophobic group having 4 or more carbon atoms is preferably used because the water dispersibility and the pot life are further improved.
  • Examples of the unsaturated monomer containing a hydrophobic group having 4 or more carbon atoms include (meth) acrylates each containing an alkyl group having 4 to 22 carbon atoms, such as n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and octadecyl (meth) acrylate; cycloalkyl (meth) acrylates, such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; cycloalkylalkyl (meth) acrylates, such as cyclopentylmethyl (meth)
  • acrylic polymers (b1) and (b2) a known and commonly used monomer, such as alkyl (meth) acrylates having 3 or less carbon atoms, e.g., methyl (meth) acrylate, ethyl (meth) acrylate, or n-propyl (meth) acrylate, can be used in combination with the monomer described above.
  • alkyl (meth) acrylates having 3 or less carbon atoms e.g., methyl (meth) acrylate, ethyl (meth) acrylate, or n-propyl (meth) acrylate
  • the monomer raw material for the acrylic polymer (b1) preferably contains 11 mol%or more and 35 mol%or less of the acrylic monomer (x) because the water dispersibility and the pot life are further improved.
  • the monomer raw material for the acrylic polymer (b2) preferably contains 2 mol%or more and less than 11 mol%of the acrylic monomer (x) because the water dispersibility and the pot life are further improved.
  • the monomer raw material for each of the acrylic polymers (b1) and (b2) preferably contains 1%to 10%by mass of the monomer having an active hydrogen-containing group because the water dispersibility and the pot life are further improved.
  • Each of the acrylic polymers (b1) and (b2) preferably has a hydroxyl value of 5 to 50 mgKOH/g because the water dispersibility and the pot life are further improved.
  • the hydroxyl value according to an embodiment of the present invention is defined as a calculated value determined from the raw materials used.
  • acrylic polymers (b1) and (b2) Various known and commonly used polymerization methods can be employed for the formation of the acrylic polymers (b1) and (b2) .
  • a radical solution polymerization method in an organic solvent is convenient and preferable.
  • polymerization initiators can be used.
  • examples thereof include azo compounds, such as 2, 2′-azobis (isobutyronitrile) , 2, 2′-azobis (2, 4-dimethylbutyronitrile) , and 2, 2′-azobis (2-methylbutyronitrile) ; and peroxides, such as tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, and diisopropyl peroxycarbonate.
  • azo compounds such as 2, 2′-azobis (isobutyronitrile) , 2, 2′-azobis (2, 4-dimethylbutyronitrile) , and 2, 2′-azobis (2-methylbutyronitrile)
  • peroxides such as tert-butyl peroxypivalate, tert-butyl peroxybenzo
  • any compound that is not reactive with an isocyanate group can be used.
  • examples thereof include aliphatic or alicyclichydrocarbon compounds, such as n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane; aromatic hydrocarbon compounds, such as toluene, xylene, and ethylbenzene; ester compounds, such as ethyl acetate, n-butyl acetate, n-amyl acetate, and ethylene glycol monomethyl ether acetate; ketone compounds, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, and cyclohexanone; poly (alkylene glycol) dialkyl ether compounds, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol di
  • the acrylic polymer (b) contains the acrylic polymers (bi) and (b2) .
  • a method for producing the acrylic polymer (b) a method is preferred in which the monomer raw material for the acrylic polymer (b2) is polymerized in the presence of the acrylic polymer (b1) because the water dispersibility and the pot life are further improved.
  • Each of the acrylic polymers (b1) and (b2) preferably has a weight-average molecular weight of 5,000 to 100,000 because the water dispersibility and the pot life are further improved.
  • the acrylic polymer (b) preferably has a hydroxyl value of 5 to 50 mgKOH/g because the water dispersibility and the pot life are further improved.
  • the isocyanate group-containing hydrophobic polyisocyanate (A) is preferably allowed to react with the acrylic polymer (b) in excess of the equivalent weight of the active hydrogen-containing group of the acrylic polymer (b) .
  • the equivalent ratio of the isocyanate group to the active hydrogen-containing group is preferably in the range of 10 to 80.
  • the water-dispersible polyisocyanate composition according to an embodiment of the present invention contains the hydrophobic polyisocyanate (A) and the acrylic polymer (B) and is easily obtained by the method for producing the acrylic polymer (B) described above.
  • the ratio by mass (A/b) of the hydrophobic polyisocyanate (A) to the acrylic polymer (b) is in the range of 0.8 to 6.3 because the water dispersibility and the pot life are further improved.
  • the water-dispersible polyisocyanate composition according to an embodiment of the present invention contains the hydrophobic polyisocyanate (A) and the acrylic polymer (B) .
  • the ratio by mass (A/B) of the hydrophobic polyisocyanate (A) to the acrylic polymer (B) is preferably in the range of 0.5 to 6 because the water dispersibility and the pot life are further improved.
  • a water-based curable composition according to an embodiment of the present invention contains the water-dispersible polyisocyanate composition and a water-based resin (C) having an active hydrogen-containing group reactive with an isocyanate group.
  • Examples of the active hydrogen-containing group of the water-based resin (C) include a hydroxy group, a carboxy group, an amino group, an amide group, and active methylene group-containing groups, such as an acetoacetyl group. Among these, a hydroxy group and a carboxy group are preferred.
  • Examples of the form of the water-based resin (C) include known and commonly used forms, such as water-soluble forms and water-dispersible forms, e.g., colloidal dispersions and emulsions.
  • water-based resin (C) examples include vinyl polymers, such as vinyl acetate-based resins, styrene-butadiene-based resins, styrene-acrylonitrile resins, acrylic resins, fluoroolefin resins, silicone-modified vinyl polymers, and poly (vinyl alcohol) ; synthetic resins other than vinyl polymers, such as polyester resins, polyurethane resins, phenolic resins, melamine resins, epoxy resins, alkyd resins, polyamide resins, polyether resins, and silicone resins; and naturally-occurring polymers, such as animal protein, starch, cellulose derivatives, dextrin, and gum arabic. Among these, vinyl polymers and various synthetic resins other than vinyl polymers are preferred. These water-based resins (C may be used alone or in combination of two or more.
  • vinyl polymers such as vinyl acetate-based resins, styrene-butadiene-based resins, styren
  • the amount of the active hydrogen-containing group contained in the water-based resin (C) is preferably in the range of 0.1 to 6 mol, more preferably 0.2 to 4 mol, even more preferably 0.4 to 3 mol per 1,000 g of the solid content of the water-based resin in view of the curability of the water-based curable composition according to an embodiment of the present invention and the water resistance of a cured article to be formed.
  • the ratio of (1) the amount by mole of the isocyanate groups in the polyisocyanate composition to (2) the total amount by mole of the active hydrogen-containing group in the water-based resin (C) and the blocked active hydrogen-containing group contained in the NCO group-containing vinyl polymer (B) , i.e., (1) / (2) is preferably in the range of 0.1 to 5, more preferably 0.3 to 3, even more preferably 0.5 to 2 in view of the curability of the curable composition and the performance of a cured article formed from the composition.
  • the water-based curable composition according to an embodiment of the present invention can be used as a pigment-free clear composition.
  • the water-based curable composition according to an embodiment of the present invention can further contain various known and commonly used organic or inorganic pigments and thus can be used as a colored composition.
  • the water-based curable composition thus prepared can be used for various applications, such as paints, adhesives, inks, waterproofing materials, sealing agents, impregnation treatment agents for various fibers, e.g., natural fibers, synthetic fibers, and glass fibers, and paper, and surface treatment agents for various fibers, e.g., natural fibers, synthetic fibers, and glass fibers, and paper.
  • the water-based curable composition is preferably used for a water-based paint.
  • a water-based paint according to an embodiment of the present invention has a long pot life and provides a cured coating film excellent in appearance and so forth.
  • the water-based paint according to an embodiment of the present invention can further contain known and commonly used various additives suitable for various applications, such as fillers, leveling agents, thickeners, defoamers, organic solvents, ultraviolet absorbers, antioxidants, and pigment dispersants, as components other than the foregoing water-based curable composition according to an embodiment of the present invention, if necessary.
  • various additives suitable for various applications such as fillers, leveling agents, thickeners, defoamers, organic solvents, ultraviolet absorbers, antioxidants, and pigment dispersants, as components other than the foregoing water-based curable composition according to an embodiment of the present invention, if necessary.
  • Examples of a base material onto which the water-based paint according to an embodiment of the present invention is applied include various metal basematerials, inorganic base materials, plastic base materials, inorganic fibers, such as paper, synthetic fibers, natural fibers, and glass fibers, cloths, synthetic leathers, natural leathers, and woody base materials.
  • metal base materials include metals, such as iron, nickel, aluminum, chromium, zinc, tin, copper, and lead; alloys of various metals described above, such as stainless steel and brass; and various surface-treated metals and alloys in which the foregoing various metals and alloys have been subjected to surface treatment, such as plating or chemical conversion treatment.
  • Examples of the inorganic base materials include hardened articles produced from calcium compounds, such as calcium silicate, calcium aluminate, calcium sulfate, and calcium oxide; ceramic materials produced by sintering metal oxides, such as alumina, silica, and zirconia; tiles produced by sintering various clay minerals; and various glasses.
  • Typical examples of the hardened articles produced from calcium compounds include hardened articles of cement compositions, such as concrete and mortar, asbestos cement boards and sheets, hardened articles of autoclaved lightweight concrete (ALC) , hardened articles of dolomite plaster, hardened articles of gypsum plaster, and calcium silicate boards.
  • plastic base materials include formed articles of thermoplastic resins, such as polystyrene, polycarbonates, poly (methyl methacrylate) , acrylonitrile-butadiene-styrene (ABS) resins, poly (phenylene oxide) , polyurethane, polyethylene, poly (vinyl chloride) , polypropylene, poly (butylene terephthalate) , and poly (ethylene terephthalate) ; and formed articles of various thermosetting resins, such as unsaturated polyester resins, phenolic resins, crosslinked polyurethane, crosslinked acrylic resins, and crosslinked saturated polyester resins.
  • thermoplastic resins such as polystyrene, polycarbonates, poly (methyl methacrylate) , acrylonitrile-butadiene-styrene (ABS) resins, poly (phenylene oxide) , polyurethane, polyethylene, poly (vinyl chloride) , polypropylene, poly (butylene terephthal
  • Coated base materials in which various base materials as described above have been coated can be used. Moreover, the coated base materials in which the deterioration of coated portions has progressed can also be used.
  • the water-based paint according to an embodiment of the present invention is applied to such a base material by a known and commonly used coating method, such as brush coating, roller coating, spray coating, dip coating, coating with a flowcoater, coating with a roll coater and then allowed to stand at room temperature for about 1 to about 10 days or heated in a temperature range of 40°C to 250°C for about 30 seconds to about 2 hours, thereby enabling the formation of a cured coating film excellent in appearance and so forth.
  • a known and commonly used coating method such as brush coating, roller coating, spray coating, dip coating, coating with a flowcoater, coating with a roll coater and then allowed to stand at room temperature for about 1 to about 10 days or heated in a temperature range of 40°C to 250°C for about 30 seconds to about 2 hours, thereby enabling the formation of a cured coating film excellent in appearance and so forth.
  • ′′PMA′′ propylene glycol monomethyl ether acetate
  • methoxy poly (ethylene glycol) methacrylate containing 23 oxyethylene units on average per molecule
  • ′′BA′′ butyl acrylate
  • ′′2-HEMA′′ 2-hydroxyethyl methacrylate
  • ′′P-O′′ rert-butyl per
  • the resulting mixture was maintained for 1 hour at 110°C.
  • Amixture of 403 parts by mass of ′′MPEGMA-i′′ , 378 parts by mass of BA, 41 parts by mass of 2-HEMA, and 50 parts by mass of P-O was added dropwise thereinto over a period of 2.5 hours.
  • the resulting mixture was allowed to react at 110°C for 9 hours to prepare a solution of an acrylic polymer (b-1) containing an acrylic polymer (b1-1) and an acrylic polymer (b2-1) and having a non-volatile content of 50%by mass.
  • the acrylic polymer (b-1) had a hydroxyl value of 21.5 mgKOH/g.
  • Table 1 presents monomer compositions used for the preparation of the acrylic polymers (b-1) to (b-4) in Synthesis examples 1 to 4.
  • Table 2 presents monomer compositions used for the preparation of the acrylic polymers (Rb-1) ⁇ (Rb-3) in Synthesis examples 5 to 7.
  • the mixture was heated to 100°C under a nitrogen stream and then allowed to react at the same temperature for 6 hours under stirring to give a water-dispersible polyisocyanate composition (1) having a non-volatile content of 82.5%by mass and an NCO group content of 13.3%by mass.
  • Water-dispersible polyisocyanate compositions (2) to (8) were prepared as in Example 1, except that the hydrophobic polyisocyanate (A-i) and the acrylic polymer (b-1) used in Example 1 were changed as given in Tables 3 and 4.
  • Comparative Example 1 to 3 Synthesis of Water-Dispersible Polyisocyanate Compositions (Ri) to (R3) )
  • Water-dispersible polyisocyanate compositions (Ri) to (R3) were prepared as in Example 1, except that the hydrophobic polyisocyanate (A-i) and the acrylic polymer (b-1) used in Example 1 were changed as given in Table 5.
  • Tables 3 and 4 present compositions of the polyisocyanate compositions (1) to (8) prepared in Examples 1 to 8.
  • Table 5 presents compositions of the polyisocyanate compositions (Ri) to (R3) prepared in Comparative examples 1 to 3.
  • the water-dispersible polyisocyanate composition (1) prepared in Example 1 and a water-based resin ( ′′Burnock WD-551′′ , available from DIC Corporation, non-volatile content: 44%by mass, hydroxyl value of solid content: 100 mgKOH/g) were mixed in such a manner that the ratio by mole of isocyanate groups in the water-dispersible polyisocyanate composition (1) to hydroxy groups in the water-based resin, i.e., (NCO/OH) , was 1.2/1.
  • the mixture was diluted with water so as to have a viscosity of 500mPa ⁇ s or less (Brookfield typeviscometer, 25°C, No. 2 rotor, 30 rpm) . Thereby, a water-based curable composition (1) was prepared.
  • the viscosity of the water-based curable composition (1) was measured immediately after the preparation and every hour after the preparation.
  • the pot life was determined by subtracting 1 hour from the time when the viscosity exceeded 2,000 mPa ⁇ s.
  • the pot life was evaluated according to the following evaluation criteria.
  • the water-based curable composition (1) was applied onto a glass plate with an applicator to a dry thickness of 30 ⁇ m and dried at 60°C for 2 hours to produce a cured coating film.
  • the appearance of the resulting cured coating film was evaluated according to the following evaluation criteria.
  • Water-based curable compositions (2) to (8) were prepared in the same manner as in Example 9, except that the water-dispersible polyisocyanate composition (1) used in Example 9 was changed to the water-dispersible polyisocyanate compositions (2) to (8) , and then evaluated similarly.
  • Comparative Example 4 to 6 Preparation and Evaluation of Water-Based Curable Compositions (R-i) to (R-3) )
  • Water-based curable compositions (R-i) to (R-3) were prepared in the same manner as in Example 9, except that the water-dispersible polyisocyanate composition (1) used in Example 9 was changed to the water-dispersible polyisocyanate compositions (Ri) to (R3) , and then evaluated similarly.
  • Tables 6 to 8 present the evaluation results of Examples 9 to 16 and Comparative examples 4 to 6.
  • the water-dispersible polyisocyanate composition of Comparative example 1 was an example of a water-dispersible polyisocyanate composition prepared without using the acrylic polymer (b2) , which is an essential raw material in an embodiment of the present invention.
  • the water-dispersible polyisocyanate composition of Comparative example 2 was an example of a water-dispersible polyisocyanate composition prepared without using the acrylic polymer (b1) , which is an essential raw material in an embodiment of the present invention. The results indicated that the water-based curable composition prepared by using the water-dispersible polyisocyanate composition of Comparative example 2 provided the coating film having poor appearance.
  • the water-dispersible polyisocyanate composition of Comparative example 3 was an example of a water-dispersible polyisocyanate composition prepared by using only one type of acrylic polymer serving as a raw material. The results indicated that the water-based curable composition prepared by using the water-dispersible polyisocyanate composition of Comparative example 3 had a poor pot life.

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  • Chemical & Material Sciences (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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  • Paints Or Removers (AREA)

Abstract

A water-dispersible polyisocyanate composition contains a hydrophobic polyisocyanate (A) and an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group. The acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate. The acrylic polymer (b) contains a polymer (bl) and a polymer (b2). The polymer (bl) is derived from a monomer raw material containing 11 mol% or more and 35 mol% or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group. The polymer (b2) is derived from a monomer raw material containing 2 mol% or more and less than 11 mol% of the acrylic monomer (x). The water-dispersible polyisocyanate composition provides a long pot life in the form of a two-component paint and excellent appearance of a coating film to be formed and thus can be sutibaly used for various paint applications.

Description

    WATER-DISPERSIBLE POLYISOCYANATE COMPOSITION, METHOD FOR PRODUCING COMPOSITION, WATER-BASED CURABLE COMPOSITION, WATER-BASED PAINT, AND ARTICLE [Technical Field]
  • Embodiments of the present invention relate to a water-dispersible polyisocyanate composition, a method for producing the composition, a water-based curable composition, a water-based paint, and an article.
  • [Background Art]
  • Regarding room-temperature crosslinkable two-component urethane coating compositions used as solvent paints, water-based ones have recently been desired from the viewpoint of environmental protection. Polyisocyanates used as curing agents in two-component urethane coating compositions, however, do not readily disperse in water and react readily with water to generate carbon dioxide. To deal with this, polyisocyanates that have emulsifiability and suppress the reaction between isocyanate groups and water even in a water-dispersed state have been reported (for example, see Patent Literatures 1 and 2) .
  • Patent Literatures 1 and 2 disclose water-dispersible polyisocyanate compositions containing a polyisocyanate and a nonionic group-containing vinyl polymer. However, even these isocyanate compositions disadvantageously have short pot lives as two-component urethane coatings.
  • [Citation List]
  • [Patent Literature]
  • [PTL 1]
  • Japanese Unexamined Patent Application Publication No.  2002-194237
  • [PTL 2]
  • Japanese Unexamined Patent Application Publication No. 2006-009029
  • [Summary of Invention]
    • [Technical Problem]
  • It is an object of the present invention to provide a water-dispersible polyisocyanate composition that has excellent water dispersibility and that provides a long pot life in the form of a two-component paint and excellent appearance of a coating film to be formed, a method for producing the composition, and a water-based paint containing the composition.
  • [Solution to Problem]
  • The inventors have conducted intensive studies in order to solve the foregoing problems and have found that a water-dispersible polyisocyanate composition containing a hydrophobic polyisocyanate and a specific acrylic polymer provides a long pot life after mixing two components and excellent appearance of a coating film to be formed. These findings have led to the completion of the present invention.
  • One aspect of the present invention is directed to providing a water-dispersible polyisocyanate composition that contains a hydrophobic polyisocyanate (A) and an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group, in which the acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate, the acrylic polymer (b) contains an acrylic polymer (b1) and an acrylic polymer (b2) , the acrylic polymer (b1) is derived from a monomer raw material containing 11 mol%or more and 35 mol%or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group, and the  acrylic polymer (b2) is derived from a monomer raw material containing 2 mol%or more and less than 11 mol%of the acrylic monomer (x) .
  • [Advantageous Effects of Invention]
  • The water-dispersible polyisocyanate composition according to an embodiment of the present invention provides a long pot life after mixing two components and excellent appearance of a coating film to be formed and thus can be suitably used in various paints for, for example, interiors and exteriors of automobiles, automobile repairs, plastics, industrial machinery, building materials, and woodworking.
  • [Description of Embodiments]
  • A water-dispersible polyisocyanate composition according to an embodiment of the present invention contains a hydrophobic polyisocyanate (A) and an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group, in which the acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate, the acrylic polymer (b) contains an acrylic polymer (bl) and an acrylic polymer (b2) , the acrylic polymer (b1) is derived from a monomer raw material containing 11 mol%or more and 35 mol%or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group, and the acrylic polymer (b2) is derived from a monomer raw material containing 2 mol%or more and less than 11 mol%of the acrylic monomer (x) .
  • The hydrophobic polyisocyanate (A) has no hydrophilic group. Examples of the hydrophobic polyisocyanate (A) include aliphatic diisocyanates, such as 1, 4-tetramethylene diisocyanate, ethyl 2, 6-diisocyanatohexanoate, 1, 6-hexamethylene diisocyanate, 1, 12-dodecamethylene diisocyanate, and 2, 2, 4-or 2, 4, 4-trimethylhexamethylene diisocyanate; aliphatic triisocyanates, such as  1, 3, 6-hexamethylene triisocyanate, 1, 8-diisocyanato-4- (isocyanatomethyl) octane, and 2-isocyanatoethyl (2, 6-diisocyanato) hexanoate; alicyclic diisocyanates, such as 1, 3-bis (isocyanatomethylcyclohexane) , 1, 4-bis (isocyanatomethylcyclohexane) , 1, 3-diisocyanatocyclohexane, 1, 4-diisocyanatocyclohexane, 3, 5, 5-trimethyl (3-isocyanatomethyl) cyclohexyl isocyanate, dicyclohexylmethane 4, 4′-diisocyanate, 2, 5-diisocyanatomethylnorbornane, and 2, 6-diisocyanatomethylnorbornane; alicyclic triisocyanates, such as 2, 5-diisocyanatomethyl-2-isocyanatopropylnorbornane, and 2, 6-diisocyanatomethyl-2-isocyanatopropylnorbornane; aralkylene diisocyanates, such as m-xylylene diisocyanate, α, α, α′, α′-tetramethyl-m-xylylene diisocyanate; aromatic diisocyanates, such as m-or p-phenylene diisocyanate, tolylene-2, 4-diisocyanate, tolylene-2, 6-diisocyanate, diphenylmethane-4, 4′-diisocyanate, naphthalene-1, 5-diisocyanate, diphenyl-4, 4′-diisocyanate, 4, 4′-diisocyanato-3, 3′-dimethylbiphenyl, 3-methyldiphenylmethane-4, 4′-diisocyanate, and diphenyl ether-4, 4′-diisocyanate; aromatic triisocyanates, such as triphenylmethane triisocyanate and tris (isocyanatophenyl) thiophosphate; polyisocyanates having a uretdione structure formed by the cyclodimerization of isocyanate groups of the diisocyanates or triisocyanates described above; polyisocyanates having an isocyanurate structure formed by the cyclotrimerization of isocyanate groups of the diisocyanates or triisocyanates described above; polyisocyanates having a biuret structure formed by the reaction of the diisocyanates or triisocyanates described above and water; polyisocyanates having an oxadiazinetrione structure formed by the reaction of the diisocyanates or triisocyanates described above and carbon dioxide; and polyisocyanates having an allophanate structure. These hydrophobic polyisocyanates (A) may be used alone or in combination of two or more.
  • Among these hydrophobic polyisocyanates (A) , aliphatic or alicyclic diisocyanates or triisocyanates, aralkylene diisocyanates, and polyisocyanates derived therefrom are preferred in view of the stability of isocyanate groups in water and the weatherability of a coating film formed from a paint containing the water-dispersible polyisocyanate composition. Among these polyisocyanates, polyisocyanates having three or more functionalities, such as isocyanurate-type polyisocyanates, polyisocyanates having a biuret structure, polyisocyanates having a uretdione structure, polyisocyanates having an allophanate structure, and polyisocyanates formed by the reaction of diisocyanates and trihydric or higher polyhydric alcohols, are preferred in order to prepare a water-based curable composition excellent in weatherability and durability. A hydrophilic group-containing polyisocyanate may be used in combination with the hydrophobic polyisocyanate (A) as long as the stability of the water-dispersible polyisocyanate composition according to an embodiment of the present invention is not impaired.
  • The acrylic polymer (B) has an alkoxy group end-capped polyoxyalkylene group. The polyoxyalkylene group can be easily introduced by the use of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group as the monomer raw material for the acrylic polymer (b) .
  • Examples of the polyoxyalkylene group include a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, polyoxyalkylene groups formed by random or block copolymerization of different oxyalkylenes, and polyoxyalkylene groups formed by ring-opening polymerization of dioxolane. Among these polyoxyalkylene groups, a polyoxyalkylene group containing an oxyethylene unit as an essential structural unit is preferred because water dispersibility is further improved.
  • The polyoxyalkylene group preferably has 12 to 30 oxyalkylene group repeat units because the water dispersibility and the pot life are further improved.
  • Preferred examples of the terminal alkoxy group include lower alkoxy groups, such as a methoxy group, an ethoxy group, and a butoxy group.
  • The acrylic polymer (b) contains the acrylic polymer (b1) and the acrylic polymer (b2) . This provides excellent pot life after mixing two components.
  • The monomer raw material for the acrylic polymer (b1) contains 11 mol%or more and 35 mol%or less, preferably 12 mol%or more and 24 mol or less of the acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group because a longer pot life is achieved.
  • The monomer raw material for the acrylic polymer (b2) contains 2 mol%or more and less than 11 mol%, preferably 5 mol%or more and 10 mol%or less of the acrylic monomer (x) because a longer pot life is achieved.
  • Examples of the acrylic monomer (x) include methoxy poly (ethylene glycol) (meth) acrylate, ethoxy poly (ethylene glycol) (meth) acrylate, propoxy poly (ethylene glycol) (meth) acrylate, butoxy poly (ethylene glycol) (meth) acrylate, phenoxy poly (ethylene glycol) (meth) acrylate, methoxy poly (propylene glycol) (meth) acrylate, ethoxy poly (propylene glycol) (meth) acrylate, propoxy poly (propylene glycol) (meth) acrylate, butoxypoly (propylene glycol) (meth) acrylate, phenoxy poly (propylene glycol) (meth) acrylate, methoxy poly (butylene glycol) (meth) acrylate, ethoxy poly (butylene glycol) (meth) acrylate, propoxy poly (butylene glycol) (meth) acrylate, butoxy poly (butylene glycol) (meth) acrylate, phenoxy poly (butylene glycol) (meth) acrylate, methoxy  poly (ethylene glycol) -poly (propylene glycol) (meth) acrylate, phenoxy poly (ethylene glycol) -poly (propylene glycol) (meth) acrylate, methoxy poly (ethylene glycol) -poly (butylene glycol) (meth) acrylate, and phenoxy poly (ethylene glycol) -poly (butylene glycol) (meth) acrylate. Among these, polyoxyethylene group-containing acrylic monomers (x) are preferred because satisfactory water dispersibility is provided. These acrylic monomers (x) may be used alone or in combination of two or more.
  • The term ″ (meth) acrylate″ described in this specification refers to one or both of methacrylate and acrylate.
  • The acrylic polymer (B) is a reaction product of the acrylic polymer (b) and the hydrophobic polyisocyanate and is easily prepared by introducing an active hydrogen-containing group into the acrylic polymer (b1) and/or the acrylic polymer (b2) andallowingthe acrylicpolymer (b1) and/or the acrylicpolymer (b2) to react with the hydrophobic polyisocyanate.
  • The active hydrogen-containing group can be easily introduced into the acrylic polymer by the use of an unsaturated monomer having an active hydrogen-containing group as a monomer raw material for the acrylic polymer (b1) and/or the acrylic polymer (b2) .
  • Examples of the unsaturated monomer having an active hydrogen-containing group include hydroxy group-containing unsaturated monomers, carboxy group-containing unsaturated monomers, amino group-containing unsaturated monomers, and active methylene group-containing unsaturated monomers. Hydroxy group-containing unsaturated monomers are preferred. These unsaturated monomers having active hydrogen-containing groups may be used alone or in combination of two or more.
  • Examples of such a hydroxy group-containing unsaturated monomer  include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxy-n-butyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-n-butyl (meth) acrylate, 3-hydroxy-n-butyl (meth) acrylate, 1, 4-cyclohexanedimethanol mono (meth) acrylate, glycerol mono (meth) acrylate, poly (ethylene glycol) mono (meth) acrylate, poly (propylene glycol) mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl 2-hydroxyethyl phthalate, and lactone-modified (meth) acrylate having a terminal hydroxy group. These hydroxy group-containing unsaturated monomers may be used alone or in combination of two or more.
  • For the monomer raw materials for the acrylic polymer (bl) and (b2) , an unsaturated monomer containing a hydrophobic group having 4 or more carbon atoms is preferably used because the water dispersibility and the pot life are further improved.
  • Examples of the unsaturated monomer containing a hydrophobic group having 4 or more carbon atoms include (meth) acrylates each containing an alkyl group having 4 to 22 carbon atoms, such as n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and octadecyl (meth) acrylate; cycloalkyl (meth) acrylates, such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; cycloalkylalkyl (meth) acrylates, such as cyclopentylmethyl (meth) acrylate, cyclohexylmethyl (meth) acrylate, and 2-cyclohexylethyl (meth) acrylate; aralkyl (meth) acrylates, such as benzyl (meth) acrylate and 2-phenylethyl (meth) acrylate; aromatic vinyl monomers, such as styrene, p-tert-butylstyrene, α-methylstyrene, andvinyltoluene; vinyl esters of carboxylic acids having 5 or more carbon atoms, such as vinyl pivalate, vinyl versatate, and vinyl benzoate; crotonates containing an alkyl group having 4 to 22 carbon atoms,  such as n-butyl crotonate and 2-ethylhexyl crotonate; diesters of unsaturated dibasic acids containing at least one alkyl group having 4 to 22 carbon atoms, such as di-n-butyl maleate, di-n-butyl fumarate, and di-n-butyl itaconate; alkyl vinyl ethers containing an alkyl group having 4 to 22 carbon atoms, such as n-butyl vinyl ether and n-hexyl vinyl ether; and cycloalkyl vinyl ethers, such as cyclopentyl vinyl ether, cyclohexyl vinyl ether, and 4-methylcyclohexyl vinyl ether.
  • For the acrylic polymers (b1) and (b2) , a known and commonly used monomer, such as alkyl (meth) acrylates having 3 or less carbon atoms, e.g., methyl (meth) acrylate, ethyl (meth) acrylate, or n-propyl (meth) acrylate, can be used in combination with the monomer described above.
  • The monomer raw material for the acrylic polymer (b1) preferably contains 11 mol%or more and 35 mol%or less of the acrylic monomer (x) because the water dispersibility and the pot life are further improved.
  • The monomer raw material for the acrylic polymer (b2) preferably contains 2 mol%or more and less than 11 mol%of the acrylic monomer (x) because the water dispersibility and the pot life are further improved.
  • The monomer raw material for each of the acrylic polymers (b1) and (b2) preferably contains 1%to 10%by mass of the monomer having an active hydrogen-containing group because the water dispersibility and the pot life are further improved.
  • Each of the acrylic polymers (b1) and (b2) preferably has a hydroxyl value of 5 to 50 mgKOH/g because the water dispersibility and the pot life are further improved.
  • The hydroxyl value according to an embodiment of the present invention is defined as a calculated value determined from the  raw materials used.
  • Various known and commonly used polymerization methods can be employed for the formation of the acrylic polymers (b1) and (b2) . A radical solution polymerization method in an organic solvent is convenient and preferable.
  • When the radical solution polymerization method is employed, various known and commonly used polymerization initiators can be used. Examples thereof include azo compounds, such as 2, 2′-azobis (isobutyronitrile) , 2, 2′-azobis (2, 4-dimethylbutyronitrile) , and 2, 2′-azobis (2-methylbutyronitrile) ; and peroxides, such as tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, and diisopropyl peroxycarbonate. These polymerization initiators may be used alone or in combination of two or more.
  • As the organic solvent, any compound that is not reactive with an isocyanate group can be used. Examples thereof include aliphatic or alicyclichydrocarbon compounds, such as n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane; aromatic hydrocarbon compounds, such as toluene, xylene, and ethylbenzene; ester compounds, such as ethyl acetate, n-butyl acetate, n-amyl acetate, and ethylene glycol monomethyl ether acetate; ketone compounds, such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, and cyclohexanone; poly (alkylene glycol) dialkyl ether compounds, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dibutyl ether; ether compounds, such as 1, 2-dimethoxyethane, tetrahydrofuran, and dioxane; and N-methylpyrrolidone, dimethylformamide, dimethylacetamide, and ethylene carbonate. These organic solvents may be used alone or in combination of two or more.
  • The acrylic polymer (b) contains the acrylic polymers (bi) and (b2) . As a method for producing the acrylic polymer (b) , a method is preferred in which the monomer raw material for the acrylic polymer (b2) is polymerized in the presence of the acrylic polymer (b1) because the water dispersibility and the pot life are further improved.
  • Each of the acrylic polymers (b1) and (b2) preferably has a weight-average molecular weight of 5,000 to 100,000 because the water dispersibility and the pot life are further improved.
  • The acrylic polymer (b) preferably has a hydroxyl value of 5 to 50 mgKOH/g because the water dispersibility and the pot life are further improved.
  • Regarding a method for producing the acrylic polymer (B) , the isocyanate group-containing hydrophobic polyisocyanate (A) is preferably allowed to react with the acrylic polymer (b) in excess of the equivalent weight of the active hydrogen-containing group of the acrylic polymer (b) . The equivalent ratio of the isocyanate group to the active hydrogen-containing group is preferably in the range of 10 to 80.
  • The water-dispersible polyisocyanate composition according to an embodiment of the present invention contains the hydrophobic polyisocyanate (A) and the acrylic polymer (B) and is easily obtained by the method for producing the acrylic polymer (B) described above. The ratio by mass (A/b) of the hydrophobic polyisocyanate (A) to the acrylic polymer (b) is in the range of 0.8 to 6.3 because the water dispersibility and the pot life are further improved.
  • The water-dispersible polyisocyanate composition according to an embodiment of the present invention contains the hydrophobic polyisocyanate (A) and the acrylic polymer (B) . The ratio by  mass (A/B) of the hydrophobic polyisocyanate (A) to the acrylic polymer (B) is preferably in the range of 0.5 to 6 because the water dispersibility and the pot life are further improved.
  • A water-based curable composition according to an embodiment of the present invention contains the water-dispersible polyisocyanate composition and a water-based resin (C) having an active hydrogen-containing group reactive with an isocyanate group.
  • Examples of the active hydrogen-containing group of the water-based resin (C) include a hydroxy group, a carboxy group, an amino group, an amide group, and active methylene group-containing groups, such as an acetoacetyl group. Among these, a hydroxy group and a carboxy group are preferred. Examples of the form of the water-based resin (C) include known and commonly used forms, such as water-soluble forms and water-dispersible forms, e.g., colloidal dispersions and emulsions.
  • Examples of the water-based resin (C) include vinyl polymers, such as vinyl acetate-based resins, styrene-butadiene-based resins, styrene-acrylonitrile resins, acrylic resins, fluoroolefin resins, silicone-modified vinyl polymers, and poly (vinyl alcohol) ; synthetic resins other than vinyl polymers, such as polyester resins, polyurethane resins, phenolic resins, melamine resins, epoxy resins, alkyd resins, polyamide resins, polyether resins, and silicone resins; and naturally-occurring polymers, such as animal protein, starch, cellulose derivatives, dextrin, and gum arabic. Among these, vinyl polymers and various synthetic resins other than vinyl polymers are preferred. These water-based resins (C may be used alone or in combination of two or more.
  • The amount of the active hydrogen-containing group contained in the water-based resin (C) is preferably in the range of 0.1  to 6 mol, more preferably 0.2 to 4 mol, even more preferably 0.4 to 3 mol per 1,000 g of the solid content of the water-based resin in view of the curability of the water-based curable composition according to an embodiment of the present invention and the water resistance of a cured article to be formed.
  • Regarding a preferred mixing ratio of the water-dispersible polyisocyanate composition according to an embodiment of the present invention to the water-based resin (C) , the ratio of (1) the amount by mole of the isocyanate groups in the polyisocyanate composition to (2) the total amount by mole of the active hydrogen-containing group in the water-based resin (C) and the blocked active hydrogen-containing group contained in the NCO group-containing vinyl polymer (B) , i.e., (1) / (2) , is preferably in the range of 0.1 to 5, more preferably 0.3 to 3, even more preferably 0.5 to 2 in view of the curability of the curable composition and the performance of a cured article formed from the composition.
  • The water-based curable composition according to an embodiment of the present invention can be used as a pigment-free clear composition. Alternatively, the water-based curable composition according to an embodiment of the present invention can further contain various known and commonly used organic or inorganic pigments and thus can be used as a colored composition.
  • The water-based curable composition thus prepared can be used for various applications, such as paints, adhesives, inks, waterproofing materials, sealing agents, impregnation treatment agents for various fibers, e.g., natural fibers, synthetic fibers, and glass fibers, and paper, and surface treatment agents for various fibers, e.g., natural fibers, synthetic fibers, and glass fibers, and paper. In particular, the water-based curable composition is preferably used for a water-based paint.
  • A water-based paint according to an embodiment of the present invention has a long pot life and provides a cured coating film excellent in appearance and so forth.
  • The water-based paint according to an embodiment of the present invention can further contain known and commonly used various additives suitable for various applications, such as fillers, leveling agents, thickeners, defoamers, organic solvents, ultraviolet absorbers, antioxidants, and pigment dispersants, as components other than the foregoing water-based curable composition according to an embodiment of the present invention, if necessary.
  • Examples of a base material onto which the water-based paint according to an embodiment of the present invention is applied include various metal basematerials, inorganic base materials, plastic base materials, inorganic fibers, such as paper, synthetic fibers, natural fibers, and glass fibers, cloths, synthetic leathers, natural leathers, and woody base materials.
  • Examples of the metal base materials include metals, such as iron, nickel, aluminum, chromium, zinc, tin, copper, and lead; alloys of various metals described above, such as stainless steel and brass; and various surface-treated metals and alloys in which the foregoing various metals and alloys have been subjected to surface treatment, such as plating or chemical conversion treatment.
  • Examples of the inorganic base materials include hardened articles produced from calcium compounds, such as calcium silicate, calcium aluminate, calcium sulfate, and calcium oxide; ceramic materials produced by sintering metal oxides, such as alumina, silica, and zirconia; tiles produced by sintering various clay minerals; and various glasses. Typical examples of the hardened articles produced from calcium  compounds include hardened articles of cement compositions, such as concrete and mortar, asbestos cement boards and sheets, hardened articles of autoclaved lightweight concrete (ALC) , hardened articles of dolomite plaster, hardened articles of gypsum plaster, and calcium silicate boards.
  • Examples of the plastic base materials include formed articles of thermoplastic resins, such as polystyrene, polycarbonates, poly (methyl methacrylate) , acrylonitrile-butadiene-styrene (ABS) resins, poly (phenylene oxide) , polyurethane, polyethylene, poly (vinyl chloride) , polypropylene, poly (butylene terephthalate) , and poly (ethylene terephthalate) ; and formed articles of various thermosetting resins, such as unsaturated polyester resins, phenolic resins, crosslinked polyurethane, crosslinked acrylic resins, and crosslinked saturated polyester resins.
  • Coated base materials in which various base materials as described above have been coated can be used. Moreover, the coated base materials in which the deterioration of coated portions has progressed can also be used.
  • These various base materials are used in various shapes, such as plate shapes, spherical shapes, film shapes, sheet shapes, large-sized structures, and complex-shaped assemblies, in accordance with applications without particular limitation.
  • The water-based paint according to an embodiment of the present invention is applied to such a base material by a known and commonly used coating method, such as brush coating, roller coating, spray coating, dip coating, coating with a flowcoater, coating with a roll coater and then allowed to stand at room temperature for about 1 to about 10 days or heated in a temperature range of 40℃ to 250℃ for about 30 seconds to about 2 hours, thereby enabling the formation of a cured coating film excellent in appearance and so forth.
  • [EXAMPLES]
  • The present invention will be described in detail using examples and comparative examples.
  • (Synthesis Example 1: Synthesis of Acrylic Polymer (b-1) )
  • First, 1, 730 parts by mass of propylene glycol monomethyl ether acetate (hereinafter, abbreviated as ″PMA″ ) was charged into a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet and heated to 110℃ under a nitrogen stream. Then a mixture of 564 parts by mass of methoxy poly (ethylene glycol) methacrylate (containing 23 oxyethylene units on average per molecule; hereinafter, abbreviated as ″MPEGMA-i″ ) , 219 parts by mass of butyl acrylate (hereinafter, abbreviated as ″BA″ ) , 41 parts by mass of 2-hydroxyethyl methacrylate (hereinafter, abbreviated as ″2-HEMA″ ) , and 50 parts by mass of rert-butyl peroxy-2-ethylhexanoate (hereinafter, abbreviated as ″P-O″ ) was added dropwise thereto over a period of 2.5 hours. The resulting mixture was maintained for 1 hour at 110℃. Amixture of 403 parts by mass of ″MPEGMA-i″ , 378 parts by mass of BA, 41 parts by mass of 2-HEMA, and 50 parts by mass of P-O was added dropwise thereinto over a period of 2.5 hours. After the completion of the dropwise addition, the resulting mixture was allowed to react at 110℃ for 9 hours to prepare a solution of an acrylic polymer (b-1) containing an acrylic polymer (b1-1) and an acrylic polymer (b2-1) and having a non-volatile content of 50%by mass. The acrylic polymer (b-1) had a hydroxyl value of 21.5 mgKOH/g. (Synthesis Examples 2 to 4: Synthesis of Acrylic Polymers (b-2) to (b-4) )
  • Solutions of acrylic polymers (b-2) to (b-4) having a non-volatile content of 50%by mass were prepared as in Synthesis example 1, except that the monomer components were changed as given in Table 1. Each of the acrylic polymers (b-2) to (b-4) had a hydroxyl value of 21.5 mgKOH/g.
  • (Synthesis Examples 5 and 6: Synthesis of Acrylic Polymers (Rb-1) and (Rb-2) )
  • Solutions of acrylic polymers (Rb-1) and (Rb-2) having a non-volatile content of 50%by mass were prepared as in Synthesis example 1, except that the monomer components were changed as given in Table 2. Each of the acrylic polymers (Rb-1) and (Rb-2) had a hydroxyl value of 21.5 mgKOH/g.
  • (Synthesis Example 7: Synthesis of Acrylic Polymer (Rb-3) )
  • First, 1, 730 parts by mass of PMAwas charged into a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen inlet and heated to 110℃ under a nitrogen stream. Then a mixture of 851 parts by mass of ″MPEGMA-1″ , 715 parts by mass of BA, 82 parts by mass of 2-HEMA, and 100 parts by mass of P-O was added dropwise thereto over a period of 5 hours. After the completion of the dropwise addition, the resulting mixture was allowed to react at 110℃ for 9 hours to prepare a solution of an acrylic polymer (Rb-3) having a non-volatile content of 50%by mass. The acrylic polymer (Rb-3) had a hydroxyl value of 21.5 mgKOH/g.
  • Table 1 presents monomer compositions used for the preparation of the acrylic polymers (b-1) to (b-4) in Synthesis examples 1 to 4.
  • [Table 1]
  • The abbreviations in the table are described below.
  • ″MPEGA-1″ : methoxy poly (ethylene glycol) acrylate (containing 13 oxyethylene units on average per molecule)
  • ″MPEGMA-2″: methoxy poly (ethylene glycol) methacrylate (containing 9 oxyethylene units on average per molecule)
  • Table 2 presents monomer compositions used for the preparation of the acrylic polymers (Rb-1) ～ (Rb-3) in Synthesis examples 5 to 7.
  • [Table 2]
  • (Example 1: Synthesis of Water-Dispersible Polyisocyanate Composition (1) )
  • First, 185 parts by mass of a hydrophobic polyisocyanate ( ″Burnock DN-980S″ , available from DIC Corporation, hexamethylene diisocyanate (HDI) -based isocyanurate-type polyisocyanate, isocyanate group content (hereinafter, referred to as an ″NCO group content″ ) : 21%by mass, non-volatile content: 100%by mass; hereinafter, referred to as a ″hydrophobic polyisocyanate (A-i) ″ ) and 100 parts by mass of the solution of the acrylic polymer (b-1) (solid content: 50 parts by mass) prepared in Synthesis example 1 were charged into a reaction vessel the same as used in Synthesis example 1. The mixture was heated to 100℃ under a nitrogen stream and then allowed to react at the same temperature for 6 hours under stirring to give a water-dispersible polyisocyanate composition (1) having a non-volatile content of 82.5%by mass and an NCO group content of 13.3%by mass.
  • (Examples 2 to 8: Synthesis of Water-Dispersible Polyisocyanate Compositions (2) to (8) )
  • Water-dispersible polyisocyanate compositions (2) to (8) were prepared as in Example 1, except that the hydrophobic polyisocyanate (A-i) and the acrylic polymer (b-1) used in Example 1 were changed as given in Tables 3 and 4. (Comparative Example 1 to 3: Synthesis of Water-Dispersible Polyisocyanate Compositions (Ri) to (R3) )
  • Water-dispersible polyisocyanate compositions (Ri) to (R3) were prepared as in Example 1, except that the hydrophobic polyisocyanate (A-i) and the acrylic polymer (b-1) used in Example 1 were changed as given in Table 5.
  • Tables 3 and 4 present compositions of the polyisocyanate compositions (1) to (8) prepared in Examples 1 to 8.
  • [Table 3]
  • [Table 4]
  • Table 5 presents compositions of the polyisocyanate compositions (Ri) to (R3) prepared in Comparative examples 1 to 3.
  • [Table 5]
  • (Example 9: Preparation and Evaluation of Water-Based Curable Composition (1) )
  • The water-dispersible polyisocyanate composition (1) prepared in Example 1 and a water-based resin ( ″Burnock WD-551″ , available from DIC Corporation, non-volatile content: 44%by mass, hydroxyl value of solid content: 100 mgKOH/g) were mixed in such a manner that the ratio by mole of isocyanate groups in the water-dispersible polyisocyanate composition (1) to hydroxy groups in the water-based resin, i.e., (NCO/OH) , was 1.2/1. The mixture was diluted with water so as to have a viscosity of 500mPa·s or less (Brookfield typeviscometer, 25℃, No. 2 rotor, 30 rpm) . Thereby, a water-based curable composition (1) was prepared.
  • [Evaluation of Pot Life]
  • The viscosity of the water-based curable composition (1) was measured immediately after the preparation and every hour after the preparation. The pot life was determined by subtracting 1 hour from the time when the viscosity exceeded 2,000 mPa·s. The pot life was evaluated according to the following evaluation criteria.
  • Excellent: 6 hours or more
  • Good: 5 hours
  • Poor: 4 hours or less
  • [Evaluation of Appearance of Coating Film]
  • Immediately after the preparation of the water-based curable composition (1) , the water-based curable composition (1) was applied onto a glass plate with an applicator to a dry thickness of 30 μm and dried at 60℃ for 2 hours to produce a cured coating film. The appearance of the resulting cured coating film was evaluated according to the following evaluation criteria.
  • Good: no cloudiness
  • Fair: slightly cloudy
  • Poor: very cloudy
  • (Examples 10 to 16: Preparation and Evaluation of Water-Based Curable Compositions (2) to (8) )
  • Water-based curable compositions (2) to (8) were prepared in the same manner as in Example 9, except that the water-dispersible polyisocyanate composition (1) used in Example 9 was changed to the water-dispersible polyisocyanate compositions (2) to (8) , and then evaluated similarly. (Comparative Example 4 to 6: Preparation and Evaluation of Water-Based Curable Compositions (R-i) to (R-3) )
  • Water-based curable compositions (R-i) to (R-3) were prepared in the same manner as in Example 9, except that the water-dispersible polyisocyanate composition (1) used in Example 9 was changed to the water-dispersible polyisocyanate compositions (Ri) to (R3) , and then evaluated similarly.
  • Tables 6 to 8 present the evaluation results of Examples 9 to 16 and Comparative examples 4 to 6.
  • [Table 6]
  • [Table 7]
  • [Table 8]
  • The results indicated that the water-based curable compositions prepared by using the water-dispersible polyisocyanate compositions of Examples 1 to 8 had long pot lives and provided excellent appearance of the resulting coating films.
  • The water-dispersible polyisocyanate composition of Comparative example 1 was an example of a water-dispersible polyisocyanate composition prepared without using the acrylic polymer (b2) , which is an essential raw material in an embodiment of the present invention. The results indicated that the water-based curable composition prepared by using the water-dispersible polyisocyanate composition of Comparative example 1 provided the coating film having poor appearance.
  • The water-dispersible polyisocyanate composition of Comparative example 2 was an example of a water-dispersible polyisocyanate composition prepared without using the acrylic polymer (b1) , which is an essential raw material in an embodiment of the present invention. The results indicated that the water-based curable composition prepared by using the water-dispersible polyisocyanate composition of Comparative example 2 provided the coating film having poor appearance.
  • The water-dispersible polyisocyanate composition of Comparative example 3 was an example of a water-dispersible polyisocyanate composition prepared by using only one type of acrylic polymer serving as a raw material. The results indicated that the water-based curable composition prepared by using the water-dispersible polyisocyanate composition of Comparative example 3 had a poor pot life.

Claims (7)

  1. A water-dispersible polyisocyanate composition, comprising: a hydrophobic polyisocyanate (A) ; and
    an acrylic polymer (B) containing an alkoxy group end-capped polyoxyalkylene group and an isocyanate group,
    wherein the acrylic polymer (B) is a reaction product of an acrylic polymer (b) and a hydrophobic polyisocyanate,
    the acrylic polymer (b) contains an acrylic polymer (b1) and an acrylic polymer (b2) ,
    the acrylic polymer (b1) is derived from a monomer raw material containing 11 mol%or more and 35 mol%or less of an acrylic monomer (x) having an alkoxy group end-capped polyoxyalkylene group, and
    the acrylic polymer (b2) is derived from a monomer raw material containing 2 mol%or more and less than 11 mol%of the acrylic monomer (x) .
  2. The water-dispersible polyisocyanate composition according to Claim 1, wherein the acrylic polymer (B) has 12 to 30 oxyalkylene group repeat units in the alkoxy group end-capped polyoxyalkylene group.
  3. The water-dispersible polyisocyanate composition according to Claim 1 or 2, wherein a ratio by mass (A/b) of the hydrophobic polyisocyanate (A) to the acrylic polymer (b) is in the range of 0.8 to 6.3.
  4. A water-based curable composition, comprising:
    the water-dispersible polyisocyanate composition according to any one of Claims 1 to 3; and
    a water-based resin (C) having an active hydrogen-containing group reactive with an isocyanate group.
  5. A water-based paint, comprising:
    the water-based curable composition according to Claim 4.
  6. An article coated with the water-based paint according to Claim 5.
  7. A method for producing the water-dispersible polyisocyanate composition according to any one of Claims 1 to 3, comprising: polymerizing the monomer raw material for the acrylic polymer (b2) in the presence of the acrylic polymer (b1) to form the acrylic polymer (b) .
EP21923652.8A 2021-02-02 2021-02-02 Water-dispersible polyisocyanate composition, method for producing composition, water-based curable composition, water-based paint, and article Withdrawn EP4288471A1 (en)

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