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WO2024243629A1 - Composition de revêtement opacifiée - Google Patents

Composition de revêtement opacifiée Download PDF

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Publication number
WO2024243629A1
WO2024243629A1 PCT/AU2024/050557 AU2024050557W WO2024243629A1 WO 2024243629 A1 WO2024243629 A1 WO 2024243629A1 AU 2024050557 W AU2024050557 W AU 2024050557W WO 2024243629 A1 WO2024243629 A1 WO 2024243629A1
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Prior art keywords
polymer
particles
coating composition
aqueous coating
composition according
Prior art date
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Pending
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PCT/AU2024/050557
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English (en)
Inventor
Brian Stanley Hawkett
Duc Ngoc Nguyen
Chiara NETO
Gregory Warr
Geosmin Alesha TURPIN
Siew Fong CHEONG
Timothy Warren Davey
Priya SUBRAMANIAN
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University of Sydney
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University of Sydney
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Priority claimed from AU2023901752A external-priority patent/AU2023901752A0/en
Application filed by University of Sydney filed Critical University of Sydney
Priority to AU2024281782A priority Critical patent/AU2024281782A1/en
Publication of WO2024243629A1 publication Critical patent/WO2024243629A1/fr
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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    • 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/02—Emulsion paints including aerosols
    • C09D5/024—Emulsion paints including aerosols characterised by the additives
    • C09D5/027—Dispersing agents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
    • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
    • 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
    • C09D133/00—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 only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
    • C09D133/04—Homopolymers or copolymers of esters
    • C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
    • C09D133/08—Homopolymers or copolymers of acrylic acid esters
    • 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/02—Emulsion paints including aerosols
    • C09D5/024—Emulsion paints including aerosols characterised by the additives
    • C09D5/028—Pigments; Filters
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/65—Additives macromolecular
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/66—Additives characterised by particle size
    • C09D7/68—Particle size between 100-1000 nm
    • 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
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F2438/00—Living radical polymerisation
    • C08F2438/03—Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX]
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/14—Polymer mixtures characterised by other features containing polymeric additives characterised by shape
    • C08L2205/16—Fibres; Fibrils
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/53—Core-shell polymer

Definitions

  • the present invention relates in general to coating compositions and in particular to opacified coating compositions.
  • Opacifiers play a pivotal role in many coating compositions such as paints, adhesives and the like, having the primary function of scattering and or absorbing light incident on a polymer film derived from the coating composition. How well a coating composition is able to visually obliterate a surface over which it is applied is referred to as its opacity. Titanium dioxide particles are commonly used as an opacifier in coating composition formulations and it, together with a polymer binder of the formulation, are the two main contributors to paint formulation cost.
  • Formulators are constantly seeking to balance reducing the cost of coating compositions while minimising or avoiding adversely affecting their properties.
  • Maintaining optimum distribution of opacifying particles throughout a coating composition and in the resulting polymer film derived therefrom is important to derive the best opacifying effect from the particles.
  • Formulators go to great lengths to prevent aggregation of the opacifying particles in the compositions and resulting polymer film.
  • sophisticated surfactant systems are often used to enhance distribution of the opacifying particles. While the use of surfactants to minimise opacifying particle aggregation is effective, the surfactant in polymer film derived from such compositions can be leached from the film giving rise to undesirable surface effects and compromised film durability.
  • mineral extender particles such as calcite, clay or talc can be incorporated in the formulations to reduce specula reflection down to a desired level.
  • mineral extenders may be added to a coating compositions at such a level that there is insufficient polymer binder to bind (space fill) all the pigment present.
  • the term "critical pigment volume concentration" (CPVC) is often used to describe the point where complete space filling can no longer occur.
  • the addition of mineral extender beyond the CPVC can therefore lead to the formation of air voids in the coating composition film as drying occurs. Those voids scatter light in their own right and can contribute to coating composition film opacity thereby allowing an opportunity to reduce the level of titanium dioxide and still achieve acceptable opacity.
  • the accompanying formula cost saving is at the expense of other coating composition film properties such as scrub resistance and stain resistance. In the case of stain resistance, the problem is that of stains penetrating into the voids in the film (film porosity).
  • Vesiculated polymer particles have been used in paint formulations to great effect by providing voids of air in paint films that enhance opacity without the disadvantage of film porosity.
  • Vesiculated polymer particles can be prepared in the form of an aqueous dispersion using suspension and emulsion polymerisation techniques.
  • the voids of the particles are typically filled with water.
  • the voids of the particles should become filled with air and thus enhance the opacifying properties of the particle s/applied coating.
  • the vesiculated polymer particles may also contain within their void region common opacifying particles such as titanium dioxide.
  • opacifying particles such as titanium dioxide.
  • the present invention provides an aqueous coating composition
  • a polymer binder comprising a polymer binder, opacifier particles and polymer fibres having (i) an average diameter of less than 200 nm, and (ii) a composition formed from a block copolymer arranged so as to provide the polymer fibres with a hydrophobic core and a hydrophilic shell structure, wherein the opacifier particles are not vesiculated polymer particles or contained within vesiculated polymer particles.
  • polymer films derived from the aqueous coating composition in accordance with the invention exhibit enhanced opacity relative to polymer films derived from the same composition absent the polymer fibres.
  • the polymer fibres interact with the opacifier particles to improve their distribution throughout both the composition and polymer films derived from the composition. That improved distribution is believed to be reflected in the improved opacity of the resulting polymer film, relative to a polymer film derived from the same composition absent the polymer fibres.
  • the polymer fibres are not readily leached from the resulting polymer film and advantageously do not impart adverse properties to either the composition or resulting polymer film.
  • the present invention also provides a method of producing an aqueous coating composition, the method comprising blending together a polymer binder, opacifier particles and polymer fibres having (i) an average diameter of less than 200 nm, and (ii) a composition formed from a block copolymer arranged so as to provide the polymer fibres with a hydrophobic core and a hydrophilic shell structure, wherein the opacifier particles are not vesiculated polymer particles or contained within vesiculated polymer particles.
  • the opacifier particles are selected from particles of metal oxide (e.g. titanium oxide, zinc oxide, iron oxide), carbon black, cobalt silicates, dibromanthrone, arylamide, copper phthalocyanine and combinations thereof.
  • metal oxide e.g. titanium oxide, zinc oxide, iron oxide
  • the polymer fibres have an average diameter of less than 150 nm, or less than 130 nm, or less than 110 nm, or less than 100 nm. Further aspects and/or embodiments of the invention are discussed in more detail below.
  • Figure 1 presents a plot of dry hiding power versus fPVC TiO2, which demonstrates that the inclusion of polymer fibres improves the opacity of a dry coating
  • Figure 2 presents a plot of wet hiding power versus fPVC TiO2, which demonstrates that the inclusion of polymer fibres improves the opacity of a wet coating
  • Figure 3 presents an SEM image of polymer fibres used in accordance with the invention prepared in Example 9(b).
  • the present invention provides an aqueous coating composition comprising a polymer binder.
  • Aqueous coating compositions find use in many different forms such as paints, adhesives, textile coatings, carpet backings and construction materials etc.
  • An aqueous coating composition in accordance with the present invention is well suited for use as a paint and accordingly it may be convenient to hereinafter describe the invention with an emphasis toward that form of composition.
  • the aqueous coating compositions according to the invention can be used in other forms/applications.
  • aqueous coating composition By being an “aqueous” coating composition is meant the composition is water-based and not organic solvent-based.
  • the liquid content of the coating composition will comprise at least 50 vol%, or at least 60 vol%, or at least 70 vol%, or at least 80 vol%, or at least 90 vol% water.
  • the aqueous coating composition comprises a polymer binder.
  • polymer binder Those skilled in the art will be familiar with polymer binders suitable for use in aqueous coating compositions. Such polymer binders are also known in the art as aqueous polymer binders, an aqueous dispersion of polymer particles or simply as a latex.
  • a role aqueous coating compositions may be to form a polymer fdm on the surface of a substrate on which the coating composition has been applied. That polymer fdm generally serves to at least protect the substrate from the elements and in most cases also alter the visual appearance of the substrate, for example to hide, colour or obscure sight of the substrate.
  • aqueous coating compositions comprise discrete, typically spherical-like, fdm forming particles of polymer dispersed throughout the aqueous phase.
  • fdm discrete, typically spherical-like, fdm forming particles of polymer dispersed throughout the aqueous phase.
  • those polymer particles overcome their coulombic and/or steric repulsions and begin to flatten and coalesce.
  • coalesce or “coalescence” it is meant that the polymer particles flow together to form a continuous fdm in which individual particles have lost their identity.
  • Polymer particle coalescence plays an important role in the polymer fdm formation process of aqueous coating compositions. Those skilled in the art are well versed with producing aqueous polymer binders (polymer dispersions or latexes) and their subsequent formulation into aqueous coating compositions to produce polymer fdm forming coating compositions.
  • aqueous coating compositions in accordance with the invention are intended to be fdm forming (i.e. a fdm forming aqueous coating composition).
  • aqueous coating compositions according to the present invention can advantageously comprise a diverse range of polymer binders.
  • suitable polymer binders include, but are not limited to, acrylic (e.g. styrene-acrylic copolymer, vinyl acetate -acrylic copolymer, urethane-acrylic copolymer and alkyd-acrylic copolymer) and vinyl acetate-ethylene copolymer binders.
  • reference to an acrylic polymer binder embraces all aqueous polymer dispersions that comprise polymer formed using (meth)acrylic acid monomer and/or (meth)acrylic ester (e.g. (meth)acrylates) monomer. Accordingly, the reference to an acrylic polymer binder herein embraces acrylic copolymer aqueous polymer dispersions such as styrene-acrylic copolymer, vinyl acetate -acrylic copolymer, urethane-acrylic copolymer and alkyd-acrylic copolymer aqueous polymer dispersions.
  • suitable polymer binders might therefore also be described to include, but are not limited to, acrylic and vinyl acetate-ethylene copolymer binders.
  • the polymer binder will generally be present in the aqueous coating composition in an amount ranging from about 5 wt. % to about 90 wt. %, or from about 10 wt. % to about 80 wt. %.
  • polymer that forms the polymer binder will have a weighted average molecular weight (Mw) in the range of about 10,000 to about 1,000,000, or from about 50, 000 to about 500,000.
  • Mw weighted average molecular weight
  • molecular weight is intended to be a weight average molecular weight (Mw) as measured by gel permeation chromatography.
  • the polymer binder used in accordance with the invention can advantageously be prepared using conventional techniques, apparatus and reagents well known to those skilled in the art.
  • the polymer binder will generally be formed through the polymerisation of ethylenically unsaturated monomers. Such monomers will generally be selected from those capable of undergoing free radical polymerisation in an aqueous environment.
  • the polymer binder may comprise at least two different polymerised ethylenically unsaturated monomers and present in the form of a copolymer. In the context of the present invention, the polymer binder of course also comprises water.
  • ethylenically unsaturated monomers may be used to form the polymer binder.
  • the monomers will generally be capable of being polymerised with other monomers.
  • the factors which determine copolymerisability of various monomers are well documented in the art. For example, see: Greenlee, R.Z., in Polymer Handbook 3 rd Edition (Brandup, J., and Immergut. E.H. Eds) Wiley: New York, 1989 p 11/53.
  • Suitable ethylenically unsaturated monomers that may be used include those of general formula where U and W are independently selected from the group consisting of -CO2H, -CO2R 2 , -COR 2 , -CSR 2 , -CSOR 2 , -COSR 2 , -CONH 2 , -CONHR 2 , -CONR 2 2 , hydrogen, halogen and optionally substituted C1-C4 alkyl wherein the substituents are independently selected from the group consisting of hydroxy, -CO2H, -CO2R 1 , -COR 2 , -CSR 2 , -CSOR 2 , -COSR 2 , -CN, -CONH2, -CONHR 2 , -CONR 2 2 , -OR 2 , -SR 2 , -O2CR 2 , -SCOR 2 , and - OCSR 2 ; and
  • V is selected from the group consisting of hydrogen, R 2 , -CO2H, -CO2R 2 , -COR 2 , -CSR 2 , -CSOR 2 , -COSR 2 , -CONH2, -CONHR 2 , -CONR 2 2 , -OR 2 , -SR 2 , -O2CR 2 , -SCOR 2 , and - OCSR 2 ;
  • R 2 is selected from the group consisting of optionally substituted C1-C18 alkyl, optionally substituted C2-C18 alkenyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted heteroarylalkyl, optionally substituted alkaryl, optionally substituted alkylheteroaryl and polymer chains wherein the substituents are independently selected from the group consisting of alkyleneoxidyl (e
  • Examples of such monomers include, but are not limited to, maleic anhydride, N-alkylmaleimide, N-aryhnaleimide, dialkyl fumarate and cyclopolymerisable monomers, acrylate and methacrylate esters, acrylic and methacrylic acid, styrene, acrylamide, methacrylamide, and methacrylonitrile, mixtures of these monomers, and mixtures of these monomers with other monomers.
  • the choice of comonomers is determined by their steric and electronic properties. The factors which determine copolymerisability of various monomers are well documented in the art. For example, see: Greenlee, RZ. in Polymer Handbook 3 rd Edition (Brandup, J., and Immergut, E.H Eds.) Wiley: New York. 1989 pII/53.
  • ethylenically unsaturated monomers include the following: methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobomyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, alpha-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobomyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, functional methacrylates, acrylates and styrenes selected from glycidyl methacrylate, 2- hydroxy
  • the polymer binder may also be provided with crosslinkable functionality.
  • crosslinkable functionality of the polymer binder may promote formation of a crosslinked structure of a polymer film derived from the aqueous coating composition.
  • the polymer binder may therefore be prepared using crosslinking monomers.
  • the polymer binder comprises polymerised residues of one or more crosslinking monomers.
  • Polymer binder comprising polymerised residues of one or more crosslinking monomers may herein be conveniently referred to as a crosslinkable polymer binder.
  • crosslinkable polymer binder may be prepared using various types of crosslinking monomers.
  • multi -ethylenically unsaturated monomers can be used to afford a crosslinked polymer structure through polymerisation of at least two unsaturated groups to provide a crosslink.
  • the crosslinked structure is typically provided through a free radical reaction mechanism.
  • a crosslinkable polymer binder may be prepared using ethylenically unsaturated monomers which also contain a reactive (or crosslinkable) functional group that is not susceptible to taking part in free radical reactions (i.e. "functionalised” unsaturated monomers).
  • the monomers are incorporated into the polymer backbone through polymerisation of the unsaturated group, and the resulting pendant functional group provides means through which crosslinking may occur.
  • the pairs of reactive functional groups can react through non radical reaction mechanisms to provide crosslinks. Formation of such crosslinks will generally occur during polymerisation of the monomers.
  • a variation on using complementary pairs of reactive functional groups is where the monomers are provided with non-complementary reactive functional groups.
  • the functional groups will not react with each other but instead provide sites which can subsequently be reacted with a crosslinking agent to form the crosslinks.
  • the crosslinking agents will be used in an amount to react with substantially all of the non- complementary reactive functional groups. Formation of the crosslinks under those circumstances will generally occur after the monomers polymerised to form the polymer binder.
  • a combination of those techniques for introducing crosslinkable character to the polymer binder may be used.
  • multi-ethylenically unsaturated monomers and “functionalised unsaturated monomers” mentioned above can conveniently and collectively also be referred to herein as "crosslinking ethylenically unsaturated monomers” or “crosslinking monomers”.
  • crosslinking ethylenically unsaturated monomers or “crosslinking monomers” it is meant an ethylenically unsaturated monomer through which a crosslink is or will be derived. Accordingly, a multi-ethylenically unsaturated monomer will typically afford a crosslink during polymerisation, whereas a functionalised unsaturated monomer can provide means through which a crosslink can be derived either during or after polymerisation.
  • Suitable multi-ethylenically unsaturated monomers include, but are not limited to, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, glycerol allyloxy di(meth)acrylate, l,l,l-tris(hydroxymethyl)ethane di(meth)acrylate
  • Examples of suitable pairs of monomers mentioned directly above that provide complementary reactive functional groups include JV-methylolacrylamide and itself, (isobutoxymethyl)acrylamide and itself, ⁇ -methacryloxypropyltriisopropoxysilane and itself, 2- isocyanoethyl methacrylate and hydroxyethyl acrylate, and /-butyl-carbodiimidocthyl methacrylate and acrylic acid.
  • crosslinking agents that can react with the reactive functional groups of one or more of the functionalised unsaturated monomers mentioned above include, but are not limited to, hexamethylene diamine, melamine, trimethylolpropane tris(2 -methyl- 1 -aziridine propionate) and adipic bishydrazide.
  • pairs of crosslinking agents and functionalised unsaturated monomers that provide complementary reactive groups include hexamethylene diamine and acetoacetoxyethyl methacrylate, hexamethylene diamine and glycidyl methacrylate, melamine and hydroxyethyl acrylate, trimethylolpropane tris(2-methyl-l -aziridine propionate) and acrylic acid, adipic bishydrazide and diacetone acrylamide.
  • the aqueous coating compositions according to the present invention also comprises opacifier particles.
  • the opacifier particles are used in the composition to assist with imparting opacity and colour to a polymer film derived from the composition. Opacity of the so formed polymer film occurs as a result of the opacifier particles scattering and/or absorbing light incident on the film, which in turn assists with hiding, obscuring and/or colouring a substrate surface on which the film has been applied.
  • the opacity of a polymer film derived from a coating composition in accordance with the invention is that determined by measuring the hiding power of a coating of the composition applied to a substrate.
  • the opacity of the wet composition or the dry polymer film derived from the composition can be measured.
  • the opacity of the dry polymer film derived from the composition general has the most practical relevance.
  • the method of measuring the opacity of a dry polymer film involves preparing a film of the coating composition with known characteristics (i.e. dry film thickness and density) and using a spectrophotometer to determine the reflectance of incident light on the film that is applied on top of black and white tiles. The scatter coefficient can then be calculated which in turn relates to the hiding power of the film.
  • the method of measuring the opacity of a wet polymer film involves preparing a film of the coating composition with known characteristics (i.e. wet film thickness and density) and using a cryptometer to determine the reflectance of incident light on the film that is applied on top of black and white tiles. The scatter coefficient can then be calculated which in turn relates to the hiding power of the film.
  • Opacifier particles are also know in the art as pigment particles.
  • aqueous coating compositions according to the present invention can advantageously be prepared using conventional opacifier particles.
  • the opacifier particles used in accordance with the invention are also not vesiculated polymer particles or contained within vesiculated polymer particles.
  • vesiculated polymer particles which are essentially polymer particles that typically have a central void or hollow section.
  • Vesiculated polymer particles have been used in aqueous coating compositions as opacifier particles.
  • Such vesiculated polymer particles have also been prepared with conventional opacifier particles (e.g. titanium dioxide) located or contained within their void or hollow section. While such vesiculated polymer particles have been found to impart good opacifying properties to polymer films, their manufacture is quite complex and difficult to scale commercially.
  • the aqueous coating composition in accordance with the invention may nevertheless still comprise vesiculated polymer particles, including those which contain within their structure conventional opacifier particles.
  • the present invention is based on the surprising finding that enhanced opacifying properties can be derived using a relatively simple system in which polymer fibres interact with conventional opacifier particles to improve their distribution throughout both the composition and polymer films derived from the composition. Accordingly, the enhanced opacifying properties derived through application of the present invention can advantageously be achieved without using costly and preparatively challenging vesiculated polymer particles.
  • the aqueous coating composition in accordance with the invention may nevertheless still comprise vesiculated polymer particles, including those which contain within their structure conventional opacifier particles.
  • the aqueous coating composition in accordance with the invention comprises no more than 10 wt%, or no more than 5 wt%, or no more than 2 wt% of vesiculated polymer particles, relative to the total amount of opacifying particles present.
  • the aqueous coating composition in accordance with the invention comprises no vesiculated polymer particles.
  • the present invention advantageously provides for aqueous coating compositions that can form polymer films having excellent opacity imparted with a reduced amount of conventional opacifier particles and without reliance upon vesiculated polymer particle technology.
  • the opacifier particles have an average diameter ranging from about 100 nm to about 600 nm, or from about 200 nm to about 600 nm, or from about 250 nm to about 450 nm, or about 300 nm.
  • a polymer film (wet or dry) derived from an aqueous coating composition in accordance with the present invention can exhibit higher opacity relative to a polymer film derived from the same aqueous coating composition absent the polymer fibres.
  • aqueous coating composition in accordance can advantageously be formulated with less opacifier particles and yet still provide for polymer films having excellent opacity.
  • a polymer film derived from an aqueous coating composition in accordance with the invention can exhibit the same opacity of a polymer film derived from the same composition absent the polymer fibres and having up to about 5 wt.%, or up to about 10 wt. %, or up to about 15 wt. %, or up to about 20 wt. % more opacifier particles.
  • the aqueous coating compositions in accordance with the invention can be formulated with up to about 20 wt. % less opacifier particles and yet still produce a polymer film having equivalent opacity to a polymer film derived from the same composition absent the polymer fibres and up to about 20 wt.
  • % more opacifier particles For example, if an aqueous coating composition formulation contains 25 wt% TiO2, then a 20% improvement in opacity of that formulation would mean a level of 20 wt% TiO2 (i.e. 25 - (25 x 20%)) could be used in accordance with the present invention to provide the same opacity.
  • a polymer film derived from the aqueous coating composition has an opacity that is at least 5 %, or at least 10 %, or at least 15 %, or at least 20 % higher than a polymer film derived from the same composition absent the polymer fibres.
  • the aqueous coating composition also comprises polymer fibres.
  • a polymer fibre(s) is intended to mean a mass of polymer comprising morphology characterised by a thread, worm or filament like structure.
  • the fibre morphology of the mass of polymer will have an aspect ratio >1.
  • the fibre morphology of the mass of polymer may have an aspect ratio >5, >20, >40, >60, >80, >100, or >200.
  • the polymer fibre may include non-fibre like features.
  • the polymer fibre may terminate at one or both of its thread, worm or filament like ends with a mass of polymer not having a fibre morphology, such as a globular morphology.
  • the polymer fibre may also include along its thread, worm or filament like structure (i.e.
  • the nonfibre like features may have a similar height to the average diameter of the fibre morphology.
  • a globular morphology may be relatively flat having a height similar to the average diameter of the fibre morphology.
  • the polymer fibres are provided in the form of a polymer mass comprising at least about 30 wt. %, about 40 wt. %, about 50 wt. %, about 60 wt. %, about 70 wt. %, about 80 wt. %, about 90 wt. %, or about 95 wt. % of polymer having fibre morphology.
  • polymer fibres used in accordance with the invention are intended to be a reference to features of the morphology characterised by the thread, worm or filament like structure.
  • polymer fibres used in accordance with the invention have an average diameter of less than 200 nm. That diameter is intended to be a reference to the fibre morphology of the polymer fibre and not any other feature of the polymer fibre that does not have fibre morphology.
  • the polymer fibres have an average diameter of less than 150 nm, or less than 130 nm, or less than 110 nm, or less than 100 nm.
  • the polymer fibres have an average diameter ranging from about 20 nm to 200 nm, or about 20 nm to about 150 nm, or about 20 nm to about 130 nm, or about 20 nm to about 110 nm, or about 20 nm to about 100 nm, or about 20 nm to about 90 nm, or about 20 nm to about 80 nm.
  • the fibre morphology feature of the polymer fibres used in accordance with the invention plays an important role in delivering improved opacity to polymer films derived from the aqueous coating compositions.
  • the thread, worm or filament like features of the polymer fibre is believed to interact with the opacifier particles and assist with promoting their even distribution throughout the aqueous coating composition and also throughout a polymer film derived from the composition. Such even distribution reduces or avoids undesirable aggregation of the opacifier particles and thereby maximises the opacifying effect of the particles in the composition/film.
  • the polymer fibres have an average diameter less than 100 nm.
  • providing the polymer fibres with an average diameter of less than 100 nm may provide for an optimal spatial interaction with the opacifier particles that in turn maximises the opacifying effect imparted by the opacifier particles.
  • the diameter of the polymer fibre increases, so too does the spatial separation between opacifier particles interacting with the fibre. That increase in spatial separation between the opacifier particles is believed to reduce their opacifying effect.
  • the polymer fibres have a length ranging from about 0. 1 micron to about 100 microns, or about 0.5 microns to about 20 microns.
  • the amount of polymer fibres used in the aqueous coating composition can vary depending upon the other constituent components of the composition, for example the type and amount of opacifier particles being used.
  • the optimum amount of polymer fibre to be used can be determined by simply preparing a number of test samples with a progressively increasing amount of polymer fibre and measuring the opacity of the polymer films derived from the samples. The opacity measurements will readily identify an optimum amount of polymer fibre to be used. That same data can advantageously be used to calculate how much opacifier particles can be removed from the composition while still maintaining acceptable opacity.
  • the polymer mass that provides the polymer fibres may comprising at least about 10 wt. %, about 20 wt. %, about 30 wt. %, about 40 wt. %, about 50 wt. %, about 60 wt. %, about 70 wt. %, about 80 wt. %, about 90 wt. %, or about 95 wt. % of polymer having fibre morphology.
  • Size (diameter, length etc) and morphology attributes of both the opacifier particles and polymer fibres can be determined using electron microscopy techniques such as TEM and SEM in conjunction with image analysis software (e.g. ImageJ).
  • polymer fibres having an average diameter of less than 200 nm they also have a composition formed from a block copolymer arranged so as to provide the polymer fibres with a hydrophobic core and a hydrophilic shell structure.
  • Block copolymers are known in the art to self-assemble or become arranged so as to present in the form of a polymer fibre having a core-shell structure.
  • block copolymers having a hydrophobic block and a hydrophilic block preferentially arrange into polymer fibres having a hydrophobic core and a hydrophilic shell.
  • the block copolymer from which they are formed correspondingly comprises a hydrophobic block and a hydrophilic block.
  • the polymer fibres have a composition formed from a block copolymer comprising a hydrophilic polymer block and hydrophobic polymer block that arrange so as to provide the polymer fibres with a hydrophobic core and a hydrophilic shell structure.
  • the hydrophilic and hydrophobic polymer blocks may be a homo-polymer hydrophilic block and a homo-polymer hydrophobic polymer block, respectively.
  • the hydrophilic and hydrophobic polymer blocks may in their own right each be a co-polymer hydrophilic block and co-polymer hydrophobic polymer block, respectively.
  • the hydrophilic and hydrophobic polymer blocks may independently be each made up from a combination of homo-polymer and co-polymer blocks.
  • a polymer block within the block copolymer will typically comprise no fewer than about 5 polymerised monomer units.
  • the block copolymer comprises a hydrophobic polymer block and a hydrophilic polymer block having a hydrophobic polymer block to hydrophilic polymer block molecular weight ratio ranging from about 0.5 to about 10, or about 1 to about 8, or about 3 to about 7.
  • the block copolymer used in accordance with the invention may be described as comprising an AB block copolymer structure, where A represents the hydrophilic block (that ultimately forms the shell of the polymer fibre) and B represents a hydrophobic block (that ultimately forms the core of the polymer fibre).
  • the hydrophilic and hydrophobic polymer blocks may be directly or indirectly covalently coupled.
  • hydrophilic and hydrophobic polymer blocks are directly or indirectly covalently coupled will typically depend upon the technique used for producing the block copolymer.
  • hydrophilic monomers may be polymerised to first form the hydrophilic block, followed by introduction of hydrophobic monomer to be polymerised to form the hydrophobic block that is directly covalently coupled to the hydrophilic block.
  • hydrophilic monomer may be polymerised to form the hydrophilic block and separately hydrophobic monomer may be polymerised to form the hydrophobic block. Those two separately prepared polymer blocks may then be indirectly covalently coupled through a coupling agent (CA).
  • CA coupling agent
  • the block copolymer used in accordance with the invention may be described as comprising an A-CA-B block copolymer structure, where A represents the hydrophilic block (that ultimately forms the shell of the polymer fibre) and B represents a hydrophobic block (that ultimately forms the core of the polymer fibre) and CA represents a coupling agent that covalently couples A with B.
  • Hydrophobic monomer and hydrophilic monomer may also be selectively polymerised using a polymerisation agent (PA) that also functions to indirectly couple at least one of the hydrophilic or hydrophobic polymer blocks.
  • PA polymerisation agent
  • the block copolymer used in accordance with the invention may be described as comprising an AB-PA-BA block copolymer structure, where A represents a hydrophilic block (that ultimately forms the shell of the polymer fibre) and B represents a hydrophobic block (that ultimately forms the core of the polymer fibre) and PA represents a polymerisation agent that, in this case covalently couples B with B (and consequently AB with BA).
  • each B may be the same or different
  • each A may be the same or different and each A and B may independently be a homo-polymer or co-polymer.
  • a polymerisation agent may be used to form a block copolymer comprising a PA- BA block copolymer structure, where A represents a hydrophilic block (that ultimately forms the shell of the polymer fibre) and B represents a hydrophobic block (that ultimately forms the core of the polymer fibre) and PA represents a polymerisation agent.
  • a and B may independently be a homo-polymer or co-polymer.
  • the block copolymers used in accordance with the present invention may be conveniently prepared using conventional free radical polymerisation techniques and reagents.
  • Controlled radical polymerisation can be used to effectively produce the block copolymers.
  • the Z, Z*, R or R* may be branched and/or optionally substituted.
  • an optional substituent includes where a -CH2- group in the alkyl chain is replaced by a group selected from -O-, -S-, -NR a -, -C(O)- (i.e. carbonyl), -C(O)O- (i.e. ester), and -C(O)NR a - (i.e. amide), where R a may be selected from hydrogen, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, heterocyclyl, arylalkyl, and acyl.
  • Preparation of the block copolymer will generally involve the polymerisation of ethylenically unsaturated monomers. Factors that determine copolymerisability of ethylenically unsaturated monomers are well documented in the art. For example, see: Greenlee, R. Z., in Polymer Handbook 3 rd edition (Brandup, J, and Immergut. E. H. Eds) Wiley: New York, 1989, p 11/53 (the entire contents of which are incorporated herein by reference). Examples of suitable ethylenically unsaturated monomers that may be used to prepare the block copolymers include those of general formula (I) described herein.
  • Hansch parameters for evaluating the hydrophobicity of monomers and polymers derived therefrom. Details concerning the calculation of Hansch parameters may be found in Hansch, Fujita, J. American Chemical Society, 1964, 86, pages 1616-1626; H. Kubinyi, methods and principles of medicinal chemistry, volume 1, R. Mannhold et al., PublisherVCH, Weinheim (1993); C. Hansch and A. Leo, substituent constants for correlation analysis, in chemistry and biology, Wiley, New York (1979); and C. Hansch, P. Maloney, T. Fujita and R. Muir Nature, 1962, 194, pages 178-180.
  • a hydrophilic monomer or polymer derived therefrom will have a Hansch parameter of less than or equal to 1.4 and a hydrophobic monomer or polymer derived therefrom will have a Hansch parameter of greater than 1.4.
  • hydrophobic ethylenically unsaturated monomers that may be polymerised to form the hydrophobic polymer block include, but are not limited to, styrene, alpha-methyl styrene, butyl acrylate, butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl methacrylate, hexyl methacrylate, lauryl methacrylate, stearyl methacrylate, ethyl hexyl methacrylate, crotyl methacrylate, cinnamyl methacrylate, oleyl methacrylate, ricinoleyl methacrylate, vinyl butyrate, vinyl tert-butyrate, vinyl stearate and vinyl laurate.
  • hydrophilic ethylenically unsaturated monomers that may be polymerised to form the hydrophilic polymer block include, but are not limited to, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide and methacrylamide, hydroxyethyl acrylate, N-methylacrylamide, dimethylaminoethyl methacrylate, 4- styrene sulfonic acid and phosphoethyl methacrylate.
  • hydrophobic polymer block is overall hydrophobic in character, it may contain one or more polymerised residues of hydrophilic monomer. Equally, provided the hydrophilic polymer block is overall hydrophilic in character, it may contain one or more polymerised residues of hydrophobic monomer.
  • the block copolymer that provides for the polymer fibre may also be provided with crosslinkable functionality.
  • crosslinkable functionality of the block copolymer may promote formation of a crosslinked structure within the polymer fibre itself and/or between the polymer fibre and the polymer binder.
  • the block copolymer may be prepared using crosslinking monomers.
  • the block copolymer comprises polymerised residues of one or more crosslinking monomers.
  • block copolymer comprises polymerised residues of one or more crosslinking monomers
  • those polymerised residues may be present in one or both of the hydrophilic and hydrophobic polymer blocks.
  • Polymer fibre formed from block copolymer comprising polymerised residues of one or more crosslinking monomers may herein be conveniently referred to as a crosslinkable polymer fibre.
  • crosslinkable polymer fibres may be prepared using various types of crosslinking monomers.
  • the block copolymer may be prepared using one or more of the crosslinking monomers herein described in the context of preparing the polymer binder.
  • both the block copolymer and the polymer fibre may be prepared using one or more crosslinking monomers.
  • a block copolymer used for preparing the polymer fibres used in accordance with the invention will generally have a weight average molecular weight (Mw) ranging from about 500 to about 1,000,000, or from about 5,000 to about 200,000.
  • the molecular weight of (and correspondingly the number of polymerised monomer residue repeat units that make up) the respective hydrophilic and hydrophobic polymer blocks that form the block copolymer will vary depending upon the type of monomers used. Those skilled in the art can readily select not only the type of monomers to use but also the molecular weight/number of repeat units of the respective hydrophilic and hydrophobic polymer blocks so as to produce a block copolymer that self assembles to afford the required polymer fibre morphology.
  • a hydrophilic polymer block of the block copolymer used in accordance with the invention will generally comprise 5 to about 1,000, or about 20 to about 200 polymerised monomer repeat units.
  • a hydrophobic polymer block of the block copolymer used in accordance with the invention will generally comprise about 50 to about 10,000, or about 100 to about 500 polymerised monomer repeat units.
  • the block copolymer and may be prepared in a single polymerisation reaction or multiple polymerisation reactions.
  • One or more surfactants may be used to assist with preparation of the block copolymer and/or formation of the polymer fibre.
  • a surfactant can assist with improving colloidal stability as the polymer fibre forms and also control over the resulting fibre morphology.
  • a free radical polymerisation technique is to be used in polymerising one or more ethylenically unsaturated monomers so as to form a block copolymer or polymer binder used in accordance with the invention
  • the polymerisation will usually require initiation from a source of free radicals.
  • a source of initiating radicals can be provided by any suitable means of generating free radicals, such as the thermally induced homolytic scission of suitable compound(s) (thermal initiators such as peroxides, peroxyesters, or azo compounds), the spontaneous generation from monomers (e.g. styrene), redox initiating systems, photochemical initiating systems or high energy radiation such as electron beam, X-ray or gamma-radiation.
  • suitable compound(s) thermal initiators such as peroxides, peroxyesters, or azo compounds
  • the spontaneous generation from monomers e.g. styrene
  • redox initiating systems e.g. styrene
  • photochemical initiating systems e.g. X-ray or gamma-radiation.
  • Thermal initiators are generally chosen to have an appropriate half-life at the temperature of polymerisation. These initiators can include one or more of the following compounds:
  • Photochemical initiator systems are generally chosen to have an appropriate quantum yield for radical production under the conditions of the polymerisation. Examples include benzoin derivatives, benzophenone, acyl phosphine oxides, and photo-redox systems.
  • Redox initiator systems are generally chosen to have an appropriate rate of radical production under the conditions of the polymerisation; these initiating systems can include, but are not limited to, combinations of the following oxidants and reductants: oxidants: potassium, peroxydisulfate, hydrogen peroxide, t-butyl hydroperoxide. reductants: iron (II), titanium (III), potassium thiosulfite, potassium bisulfite.
  • phenylpropenoyl e.g., phenylbutenoyl, phenylmethacryloyl, phenylpentenoyl and phenylhexenoyl and naphthylalkenoyl (e.g.
  • aryloxyalkanoyl such as phenoxyacetyl and phenoxypropionyl
  • arylthiocarbamoyl such as phenylthiocarbamoyl
  • arylglyoxyloyl such as phenylglyoxyloyl and naphthylglyoxyloyl
  • arylsulfonyl such as phenylsulfonyl and napthylsulfonyl
  • heterocycliccarbonyl heterocyclicalkanoyl such as thienylacetyl, thienylpropanoyl, thienylbutanoyl, thienylpentanoyl, thienylhexanoyl, thiazolylacetyl, thiadiazolylacetyl and tetrazolylacetyl
  • each alkyl for example C 1-20, may be the same or different
  • 5 or 6 membered rings optionally containing one or more same or different heteroatoms (e.g. O, N and S).
  • Ci-6 alkyl such as methylamino, ethylamino, propylamino etc), dialkylamino (e.g. Ci-6 alkyl, such as dimethylamino, diethylamino, dipropylamino), acylamino (e.g. NHC(O)CH3), phenylamino (wherein phenyl itself may be further substituted e.g., by Ci-6 alkyl, halo, hydroxy, hydroxyCi-6 alkyl, Ci-6 alkoxy, haloCi-6 alkyl, cyano, nitro OC(O)Ci-6 alkyl, and amino), nitro, formyl, -C(O)-alkyl (e.g.
  • Ci-6 alkyl such as acetyl
  • O-C(O)-alkyl e.g. Ci-6alkyl, such as acetyloxy
  • benzoyl wherein the phenyl group itself may be further substituted e.g., by Ci-6 alkyl, halo, hydroxy hydroxyCi-6 alkyl, Ci-6 alkoxy, haloCi-6 alkyl, cyano, nitro OC(O)Ci-6alkyl, and amino
  • C1-6 alkyl such as methyl ester, ethyl ester, propyl ester, butyl ester
  • CChphenyl wherein phenyl itself may be further substituted e.g., by C1-6 alkyl, halo, hydroxy, hydroxyl C1-6 alkyl, Ci- 6 alkoxy, halo C1-6 alkyl, cyano, nitro OC(O)Ci-6 alkyl, and amino
  • CONH2 CONHphenyl (wherein phenyl itself may be further substituted e.g., by C1-6 alkyl, halo, hydroxy, hydroxyl C1-6 alkyl, Ci -6 alkoxy, halo C1-6 alkyl, cyano, nitro OC(O)C 1-6 alkyl, and amino)
  • CONHbenzyl wherein benzyl itself may be further substituted e.g., by C1-6 alkyl, halo, hydroxy hydroxyl C1-6 alkyl, Ci -6
  • C1-6 alkyl such as methyl ester, ethyl ester, propyl ester, butyl amide) CONHdialkyl (e.g. C1-6 alkyl) aminoalkyl (e.g., HN C1-6 alkyl-, Ci-6alkylHN-Ci-6 alkyl- and (Ci-6 alkyl)2N-Ci-6 alkyl-), thioalkyl (e.g., HS C1-6 alkyl-), carboxyalkyl (e.g., HO2CC1-6 alkyl-), carboxyesteralkyl (e.g., Ci- 6 alkylCfCCi , alkyl-), amidoalkyl (e.g., H2N(O)CCI-6 alkyl-, H(Ci ⁇ alkyl)N(O)CCi-6 alkyl-), formylalkyl (e.g., OHCCusalkyl-), acylalkyl (e.g., Ci-6
  • [groupA] [group B] refers to group A when linked by a divalent form of group B.
  • [group A] [alkyl] refers to a particular group A (such as hydroxy, amino, etc.) when linked by divalent alkyl, i.e. alkylene (e.g. hydroxyethyl is intended to denote HO-CH2-CH-).
  • a solution of St (315 g), AIBN (2.52 g) and macro-RAFT solution from Example 1 (105 g) was prepared.
  • sodium hydroxide (NaOH) solution (5.39 g NaOH in 126 g water) was added in drop wise while the solution was stirred at 1500 rpm using an overhead mixer (Labortechnik, IKA) to produce a viscous white mixture.
  • 280 g of water was slowly added while the stirring was maintained to produce a white emulsion.
  • a final 392 g of water was further added to the emulsion under stirring for another 5 minutes. After being deoxygenated for 10 minutes, the mixture was heated at 80°C with a stirring rate of 150 rpm over 1.5 hours.
  • Electron microscopy showed that the final product (approximately 1.2 kg) contained 33.3 wt. % solids, about 42 wt. % of which exhibited fibre morphology, and polymer fibres having an average diameter of about 70 nm.
  • the diameters of polymer fibres exemplified herein were measured from SEM and TEM micrographs using Image J analysis software. Reported values are the average of 10 measurements, with an uncertainty equal to the standard deviation of the data, both rounded up to the nearest 10 nm
  • Example 3 Polymer fibre synthesis with poly(tert-butyl acrylate) core using the macro- RAFT agent prepared in Example 1 as a stabiliser.
  • t-BA tert-butyl acrylate
  • AIBN AIBN
  • macro-RAFT solution from Example 1 8.5 g
  • sodium hydroxide (NaOH) solution (0.43 g NaOH in 9 g water) was added in drop wise while the solution was stirred at 1500 rpm using an overhead mixer (Labortechnik, IKA) to produce a viscous white mixture.
  • 20 g of water was slowly added into the beaker while the stirring was maintained to produce white emulsion.
  • a final 28 g of water was further added to the emulsion under stirring for another 5 minutes.
  • Example 4 Preparation of a poly ⁇ (styrene)t -block- [(butyl acrylate)m-co-(acrylic acid)n] ⁇ macro-RAFT agent with a non-symmetrical trithiocarbonate RAFT agent and monomer molar ratio m « 120, n « 60 and t «80.
  • Example 5 Polymer fibre synthesis with polystyrene core using the macro-RAFT agent prepared in example 4 as a stabiliser.
  • a solution of St (21.2 g), AIBN (0. 18 g) and macro-RAFT solution from example 4 (8.5 g) was prepared in a 500 mL glass container.
  • sodium hydroxide (NaOH) solution (0.4 g NaOH in 9 g water) was added in drop wise while the solution was stirred at 1500 rpm using an overhead mixer (Labortechnik, IKA) to produce a viscous white mixture.
  • 20 g of water was slowly added into the beaker while the stirring was maintained to produce white emulsion.
  • a final 28 g of water was further added to the emulsion under stirring for another 5 minutes. After being deoxygenated for 10 minutes, the jar was sealed and immersed in an oil bath with a temperature setting of 80°C.
  • the reaction was carried out for 2 hours with magnetic stirring. Electron microscopy (SEM) showed that the final product contained 29.2 wt. % solids, about 55 wt. % of which exhibited fibre morphology, and polymer fibres having an average diameter of about 120 nm.
  • Example 6 Preparation of a poly[(butyl acrylate)m-co-(acrylic acid)n] macro-RAFT agent with dibenzyl trithiocarbonate RAFT agent and monomer molar ratio m « 120 and n « 60.
  • a solution of dibenzyl trithiocarbonate (diBenT) (0.61 g, 2.1 mmol), AIBN (0.10 g, 0.6 mmol), AA (9.15 g, 126.9 mmol), BA (32.62 g, 255.3 mmol) in dioxane (40 g) was prepared in a 250 mL round bottom flask. After being sealed and sparged with nitrogen for 10 minutes, the flask was heated at 70°C for 2.5 hours under constant stirring. The final copolymer solution had 51.9% solids.
  • Example 7 Polymer fibre synthesis with polystyrene core using the macro-RAFT agent prepared in example 4a as a stabiliser.
  • a macro-RAFT solution from example 6 (7 g) was prepared in a 200 mL glass container with 5 g water and ammonium hydroxide (NH4OH) (2.0 g, 25%) under stirring at 1000 rpm using an overhead mixer (Labortechnik, IKA) to produce a yellow mixture.
  • NH4OH ammonium hydroxide
  • St (20 g) AIBN (0.2 g) and then 40 g of water was sequentially added into while the stirring was maintained at 2000 rpm to produce white emulsion.
  • the jar was sealed and immersed in an oil bath with a temperature setting of 80°C. The reaction was carried out for 2 hours with magnetic stirring. Electron microscopy (TEM) showed that the final product contained 30.5 wt.
  • Example 8 Preparation of low sheen white coatings using polymer fibres and measurement of hiding power of the coating relative to conventional paints.
  • the intermediates were formulated into paints (8a-f) with post adjustment of latex, Texanol, water and polymer fibre (where applicable) to provide low sheen white coatings with PVC of 36-37 and volume solids of 38-40%, with a final coating composition as per Table 1.
  • the parameter that was tested was the hiding power of the coating, which is indicative of the opacity of the paints.
  • the films were allowed to dry, in constant conditions of 25°C and 50% humidity, for 24 hours. Films were then moved to a 50°C oven and left overnight.
  • Each testing section was weighed to 0.1 mg. This is the weight of the coating plus the substrate.
  • Aluminium dishes were prepared by placing in a 150°C oven for 30 minutes.
  • the wet film thickness is calculated using the following equation:
  • Rb reflectance of the film against the black tile
  • R w reflectance of the film against the white tile
  • the Hiding Power (HP) is calculated using the following formula:
  • the inventive examples that contain polymer fibres have higher dry opacities than the conventional paints that do not contain polymer fibres.
  • the parameter that was tested was the wet hiding power of the coating, which is indicative of the wet opacity of the paints.
  • Macro-RAFT solution (96 g) from example 9 (a) was added in a base solution containing 500 g water and 12.9 g NaOH under stirring. The yellow dispersion was then transferred to the 2 L reactor with an additional 64 g water. While under stirring, a monomer solution containing Styrene (264 g) and AIBN (2.16 g) was added to the reactor and was emulsified for 10 minutes. After being deoxygenated for 10 minutes, the mixture was heated at 80°C with a stirring rate of 150 rpm over 2 hours. The final product (approximately 1.0 kg) contained 36.6 wt. % solids. The fractionation method by centrifugation was used to estimate nanofibre content.
  • Example 9 (c): Crosslinked nanofibres with divinyl benzene (DVB).

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Abstract

La présente invention concerne une composition de revêtement aqueuse comprenant un liant polymère, des particules opacifiantes et des fibres polymères ayant (i) un diamètre moyen inférieur à 200 nm, et (ii) une composition formée à partir d'un copolymère séquencé agencé de façon à fournir aux fibres polymères un noyau hydrophobe et une structure de coque hydrophile, les particules opacifiantes n'étant pas des particules de polymère vésiculées ou n'étant pas contenues dans des particules de polymère vésiculées.
PCT/AU2024/050557 2023-06-02 2024-05-29 Composition de revêtement opacifiée Pending WO2024243629A1 (fr)

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Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
NGUYEN DUC, HUYNH VIEN, LAM MINH, SERELIS ALGIRDAS, DAVEY TIM, PARAVAGNA OLGA, SUCH CHRIS, HAWKETT BRIAN: "Encapsulation by Directed PISA: RAFT‐Based Polymer‐Vesiculated Pigment for Opacity Enhancement in Paint Films", MACROMOLECULAR RAPID COMMUNICATIONS, WILEY-VCH, DE, vol. 42, no. 10, 1 May 2021 (2021-05-01), DE , pages 2100008, XP093249265, ISSN: 1022-1336, DOI: 10.1002/marc.202100008 *
PHAM, BINH TT ET AL.: "Aqueous polymeric hollow particles as an opacifier by emulsion polymerization using macro-RAFT amphiphiles", LANGMUIR, vol. 34, no. 14, 2018, pages 4255 - 4263, XP093073501, DOI: 10.1021/acs.langmuir.7b03410 *

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