Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • 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
  • C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
• • 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
  • C09D7/67—Particle size smaller than 100 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
  • C09D7/66—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
  • C09D7/66—Additives characterised by particle size
  • C09D7/69—Particle size larger than 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
  • C09D7/80—Processes for incorporating ingredients
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
• • 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
• • 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
  • C08K3/24—Acids; Salts thereof
  • C08K3/26—Carbonates; Bicarbonates
• • 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
  • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
• • 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
  • C08K3/34—Silicon-containing compounds
  • C08K3/346—Clay
• • 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
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • 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
  • C08K9/00—Use of pretreated ingredients
  • C08K9/02—Ingredients treated with inorganic substances
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/16—Sizing or water-repelling agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
  • D21H23/48—Curtain coaters
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/50—Spraying or projecting
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/52—Addition to the formed paper by contacting paper with a device carrying the material
  • D21H23/56—Rolls
  • D21H23/58—Details thereof, e.g. surface characteristics, peripheral speed

Definitions

• the present invention relates to the field highly hydrophobic and superhydrophobic coatings.
• Hydrophobic, highly hydrophobic and superhydrophobic coatings are used for many kinds of surfaces.
• many approaches have been used to manufacture highly hydrophobic coatings.
• US 3,940,385 discloses glossy coating compositions where a pigment for instance with a particle size 0.2-0.5 ⁇ m is coated with an organic compound to render the pigment hydrophobic.
• the pigment is emulsified and renders the coating hydrophobic.
• Ti ⁇ 2 is mentioned as a pigment.
• Fatty acids are mentioned as compounds to be used to coat the pigment.
• DE 1033561 shows the use of both hydrophilic and hydrophobic substances to coat a hydrophobic surface.
• substances which can be included in the compositions are salts of fatty acids and hydrophobic and/or hydrophilic pigments. Also a binder is disclosed.
• US 2002/0002932 describes a paint composition which may comprise components such as Ti ⁇ 2, silica, a fatty acid, a surfactant, and an acrylic latex binder.
• WO 2005/042655 presents a aqueous ink and coating composition which consists essentially of: 20-60 wt% of an acrylic resin dispersion, 5-30 wt% of a pigment, 0.5-10 wt% of an alcohol, 20-75 wt% of an aqueous solvent, 0.5-5 wt% of a hydrogenated vegetable derived wax.
• pigment include calcium carbonate
• wax include stearic acid.
• GB 1452674 mentions a composition comprising calcium carbonate.
• paper coated with a composition including filler there is mentioned a coating paste for paper comprising calcium carbonate, calcium stearate, an acrylic emulsion and water .
• US 2,576,914 discusses coated paper and a coating composition for paper.
• it comprises a pigment, a fatty acid salt or a salt thereof, a copolymer of styrene, and water.
• JP 2005-036173 discloses an ink and in particular one embodiment comprising precipitated calcium carbonate, a polymer, and a surfactant. It is also mentioned that a fatty acid can be used to treat particles.
• US 2006/0141223 Al relates to textile sheet-like constructions having enhanced watertight properties and to a process for producing them. This fibre modification process requires solvent.
• WO 2001/062863 Al demonstrates an aqueous lacquer dispersion suitable for hydrophobic coatings.
• the material is mainly carboxylated polystyrene pigments, wherein part of the carboxylic groups are esterified with fluorinated aliphatic alcohols.
• US 2006/0257643 Al illustrates a method of producing hydrophobic composites and aggregates. The process requires several process steps and is not suited to preparing continuous coatings.
• FR 2 852 966 concerns an aqueous composition for treating surfaces and making them superhydrophobic, comprising a thermoplastic polymer in an aqueous emulsion and mineral particles having a size from 5 to 500 ⁇ m.
• the mineral can be for instance calcium carbonate, quartz, mica, talc, titanium dioxide, barium sulphate, calcium sulphate etc.
• the polymer can be for instance polystyrene, polymethacrylate, polyvinyl butyral, and polyurethane .
• US 6,712,932 shows a paper or a paper-like material with a structure that comprises particles of for instance metal oxides and carbonates, which are fixed to the paper by means of a wet-laying method using a binder together with a water-repelling agent.
• US 6,660,363 concerns self-cleaning surface comprising elevations made of hydrophobic polymers or permanently hydrophobized materials.
• US 2005/0136217 Al relates to a self-cleaning object with a layer of hydrophobic material having protrusions and recesses, which layer is applied with a solution, dispersion or emulsion containing hydrophobic material and a liquid where the liquid is evaporated.
• the mixture may also comprise other solid particles.
• hydrophobic composites particularly hydrophobic particulates and free-flowing aggregates and methods utilizing the same.
• Highly hydrophobic wet-laid coatings may be divided into two main types of coating treatments, either solvent-borne or water-borne.
• Solvent-borne treatments are subject to controls and/or regulatory limitations in some countries.
• water-borne coating treatments are usually more difficult to implement in order to obtain hydrophobic coatings and thus more limited than solvent- borne coating treatments, due to the dual requirement for a stable coating dispersion in the aqueous phase and for hydrophobicity in the dry state of the final coating layer.
• the application of the superhydrophobic coating often involves multiple steps by creating surface structure and low surface energy coating in different steps.
• standard oil-in-water emulsion-based strategies for encapsulating and delivering hydrophobic species tend to leave an emulsifier (e.g. surfactant) on the coated surface upon drying, which in turn tends to enhance wetting.
• emulsifier e.g. surfact
• the present invention relates to an aqueous dispersion suitable for use in the manufacture of a hydrophobic coating, said aqueous dispersion comprises inorganic particles, at least one fatty acid or a salt thereof, a polymeric binder, and water, wherein said aqueous dispersion is free of organic solvent.
• the present invention concerns a subject at least partly coated by contacting said substrate with an aqueous dispersion according to the present invention, wherein said subject has an equilibrium contact angle higher than 120° degrees, preferably more than 135°, more preferably more than 150° for a drop of water on the surface.
• the present invention moreover relates to use of an aqueous dispersion comprising a) inorganic particles, b) at least one fatty acid or a salt thereof, c) a polymeric binder, and d) water, as a coating on a substrate surface, wherein said surface after coating displays an equilibrium contact angle higher than 120° degrees, preferably more than 135°, most preferably more than 150° for a drop of water on the surface.
• the present invention further relates to a method for coating a substrate comprising contacting said substrate with an aqueous dispersion according to the invention. Further embodiments of the present invention are defined in the appended dependent claims, which are specifically incorporated by reference herein.
• the coating allows application in one step; it is non-toxic, safe for food packaging, and relatively environmentally friendly and inexpensive.
• a further advantage is that existing industrial coating processes can be used for applying the coating.
• Another advantage is that it is possible to obtain highly hydrophobic or superhydrophobic coatings without use of silanes or fluorinated components.
• Acicular is used herein to denote a needle-like shape.
• Antioxidant denotes a substance capable of preventing, slowing down, and/or suppressing oxidation.
• Apparent density denotes dry mass per unit volume of a material including voids inherent in the material .
• Aqueous dispersion as used herein encompasses a mixture comprising water.
• Aragonite denotes a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate. The other polymorph is the mineral calcite.
• Aragonite 's crystal lattice differs from that of calcite, resulting in a different crystal shape, an orthorombic system with acicular crystals. Repeated twinning results in pseudo-hexagonal forms.
• Aragonite may be columnar or fibrous, occasionally in branching stalactitic forms.
• Biocide as used herein denotes a substance capable of preventing, slowing down, or suppressing growth of living organisms .
• Coalescence agent as used herein denotes an agent that causes or promotes coalescence.
• Crosslink as used herein denotes any bond linking one polymer chain to another.
• D 50 denotes the 50 th percentile of the mass-weighted size distribution of particles. Accordingly 50 % of the inorganic particles have a size greater than D 5 O and 50 % of the inorganic particles have a size of less than D 50 .
• the particle size is determined for the primary particles if the particles are not aggregated in larger agglomerates, but if the particles are aggregated in larger agglomerates the size of the agglomerates is measured.
• Defined foaming agents as used herein denotes a substance capable of preventing, slowing down, or suppressing foaming .
• Fungicide as used herein denotes a substance capable of preventing, slowing down, or suppressing growth of fungi.
• Highly hydrophobic is used herein to denote a surface with an equilibrium contact angle between 120 degrees and 150 degrees for a drop of water on the surface.
• Hydrophobic as used herein denotes the property to repel water.
• a hydrophobic surface is a surface with a contact angle of more than 90 degrees but less than 120 degrees.
• Inorganic particle as used herein encompasses an inorganic particle of any shape.
• Optical brighteners include dyes that absorb light in the ultraviolet and violet region of the electromagnetic spectrum and re-emit light in the blue region .
• Polymeric binder as used herein denotes a binder that is a polymer.
• Rheology modifiers denotes a substance with the capability to modify rheological properties of a fluid.
• Scalenohedral denotes a pyramidal form under the rhombohedral system, enclosed by twelve faces, each a scalene triangle.
• Subject denotes a pure or a non-pure chemical compound or a mixture of chemical compounds, thus for instance a mineral is encompassed within the term.
• Superhydrophobic denotes a surface with an equilibrium contact angle higher than 150 degrees for a drop of water on the surface.
• an aqueous dispersion comprising a) inorganic particles, b) at least one fatty acid or a salt thereof, c) a polymeric binder, and d) water, wherein said aqueous dispersion is free of organic solvent.
• free of organic solvent means that the aqueous dispersion is essentially free of organic solvent.
• An organic solvent in this context is a carbon containing chemical. Essentially free of organic solvent means that very small amounts of organic solvent can be present, altough such small amounts are not added, they may nevertheless be present because of impurities in the ingredients. Examples of amounts of accidentally occurring organic solvents include but are not limited to 0.001 wt%, and 0.01 wt%. In one embodiment the amount of organic solvents in the aqueous dispersion is less than 0.01wt%. In one embodiment there are no organic solvents at all. It is an advantage that the dispersion is free of organic solvent since it is environmentally friendly and safe for food applications.
• an aqueous dispersion comprising a) inorganic particles comprising aragonite, wherein said inorganic particles have a D 50 of less than 20 ⁇ m, b) at least one fatty acid or a salt thereof, c) a polymeric binder, and d) water.
• the amount of inorganic particles is from about 20 to about 55 wt% of the aqueous dispersion. In another embodiment the amount of inorganic particles is from about 30 to about 45 wt%. In a further embodiment the amount of inorganic particles is from about 30 to about 40 wt% .
• the amount of at least one fatty acid or a salt thereof is from about 0.1 to about 2 wt% of the aqueous dispersion. In another embodiment the amount of at least one fatty acid or a salt thereof is from about 0.5 to about 1 wt%. In a further embodiment the amount of at least one fatty acid or a salt thereof, is from about 0.7 to about 0.8 wt%.
• the amount of a polymeric binder is from about 5 to about 20 wt% of the aqueous dispersion. In another embodiment the amount of a polymeric binder is from about 8 to about 15 wt%. In a further embodiment the amount of the amount of a polymeric binder is from about 10.5 to about 12 wt%.
• the remaining parts up to 100wt% are water and optional additives.
• the inorganic particles according to the present invention have an apparent density from about 0.30 g/ml to about 4 g/ml, and a BET specific surface area from about 1 to 20 m 2 /g.
• Apparent density from about 0.30 g/ml to about 2.7 g/ml, preferably from about 0.30 g/ml to about 0.80 g/ml and most preferably about 0.30 g/ml to about 0.65 g/ml.
• BET specific surface area from about 1 to 20 m /g, preferably more than about 3 m 2 /g and more preferably more than 5 m 2 /g.
• D 5 O less than about 20 ⁇ m, preferably from about 1 to about 10 ⁇ m, most preferably from about 2 to 5 ⁇ m.
• the inorganic particles the following properties:
• Apparent density from about 1 g/ml to about 4 g/ml, preferably from about 2 to about 3.5 g/ml and most preferably about 2.5 g/ml to about 2.9 g/ml.
• BET specific surface area from about 1 to 20 m /g, preferably more than about 6 m 2 /g and more preferably more than 9 m 2 /g.
• D 50 less than about 10 ⁇ m, preferably from about 0.1 to about 5 ⁇ m, most preferably from about 0.2 to 2 ⁇ m.
• the inorganic particles used in the present invention may comprise a mixture of different inorganic particles with different properties.
• the inorganic particles used in the present invention comprise at least one substance selected from the group consisting of anatase, calcinated clay, kaolin, and talc, the surface of which has been made basic .
• the inorganic particles used in the present invention comprise at least one substance selected from the group consisting of aluminium hydroxide, barium sulphate, calcite, calcium sulphate, dolomite, magnesium hydroxide, magnesium carbonate, magnesite, titanium dioxide (rutile) , and vaterite.
• the inorganic particles used in the present invention comprise at least one substance selected from the group consisting of zincite, corundum, hematite, magnetite, ilmenite, and cassiterite.
• the inorganic particles used in the present invention comprise at least one substance selected from the group consisting of dispore, boehmite, goethite, lepidocrocite, rhodocrosite, siderite, baryte, strontianite, apatite, feldspar and fluorite.
• the inorganic particles used in the present invention comprise Si ⁇ 2.
• the inorganic particles preferably comprise calcium carbonate particles, more preferably precipitated calcium carbonate and most preferably aragonite.
• the inorganic particles are surface treated with a fatty acid or a salt thereof.
• Advantages of using one or more fatty acids include that fatty acids are inexpensive compared to silanes and fluorinated polymers and are readily available and used in many industries.
• Fatty acids interact in a suitable way with inorganic particles comprising calcium carbonate and many fatty acids are approved for contact with food.
• the inorganic particles are coated by contacting them with an aqueous solution or dispersion comprising a fatty acid or a salt thereof.
• the aqueous solution or dispersion that comprises the fatty acid or a salt thereof further comprises the binder.
• the coating is performed in a separate aqueous solution or dispersion comprising a fatty acid or a salt thereof.
• the coating of the inorganic particles is performed in a separate aqueous solution or dispersion.
• the inorganic particles are coated with several different fatty acids of salts thereof, optionally in several steps.
• the fatty acid or salt thereof forms a layer on the entire inorganic particle surface; alternatively the fatty acid or salt thereof forms a layer on a part of the surface.
• the coating comprises at least one surfactant .
• the amount of fatty acid or salt thereof should be high enough so that the inorganic particles become dispersible in water.
• the amount of fatty acid corresponds to a double layer of molecules on the surface of the inorganic particles.
• the inorganic particles become dispersible in water or alternatively the ability to be dispersed in water is improved.
• Inorganic particles with relatively poor packing are preferred, which yields a suitable roughness of the coating.
• Inorganic particles with narrow particle size distribution are used in one embodiment.
• inorganic particles are combined with a tendency to aggregate to larger secondaries.
• the inorganic particles are acicular or scalenohedral .
• the shape of the particles is however not limited to these two shapes. Also other thorny, spiky and needle like shapes are used in other embodiments according to the present invention. Other possible shapes include but are not limited to chestnut husk shapes.
• particles with a small size, low density and high specific surface are used.
• inorganic particles without any appreciable residues of dispersants are used. It was found in some cases that dispersant added during the manufacture of particles comprising aragonite can interfere with the adsorption of fatty acid or a salt thereof on the particle surface. Examples of such undesired dispersants include but are not limited to sodium polyacrylate polymers and copolymers thereof. For certain embodiments it is therefore important to use inorganic particles with no or only very low amounts of added dispersants.
• acicular aragonite is used for the inorganic particles, especially acicular aragonite with a D 50 from about 0.1 to about 20 ⁇ m, preferably from about 0.2 to about 10 ⁇ m. It has turned out that aragonite gives coatings with high contact angle for a drop of water on the surface.
• PCC precipitated calcium carbonate
• GCC ground calcium carbonate
• a fatty acid and a salt thereof are used together .
• binders include but are not limited to carboxylated latex, styrene-butadiene latex and styrene acrylate.
• carboxylated latex is a latex or emulsion polymer stabilised predominantly by carboxylation .
• the glass transition temperature of the binder is in the range from about -40 to about 50 °C.
• the glass transition temperature of the binder is in the range from about 0 to about 50 °C.
• a polymeric binder include but are not limited to commercially available binders supplied by Dow Chemical Company®® under the trade name DL 940® or experimental latex Dow/HPQ73® or by Rhodia® under the trade name Ultradia® 7100, 7300 or 7400.
• Synthetic latex is an aqueous dispersion of polymer particles prepared by emulsion polymerization of one or more monomers.
• the first monomer (A) is a low Tg monomer comprising an alkyl acrylate or butadiene.
• the low Tg monomer is used in amounts of from about 10 pphm to about 95 pphm, preferably 15 pphm to 40 pphm.
• certain copolymerizable monomers that assist in the stability of the binder e.g., vinyl sulfonic acid, sodium vinyl sulfonate, sodium styrene sulfonate, sodium allyl ether sulfate, sodium 2-acrylamide-2-methyl-propane sulfonate (AMPS) , 2-sulfoethyl methacrylate, and 2- sulfopropyl methacrylate, can be employed as emulsion stabilizers.
• AMPS 2-acrylamide-2-methyl-propane sulfonate
• 2-sulfoethyl methacrylate 2-sulfopropyl methacrylate
• redox initiators may be employed, especially when polymerization is carried out at lower temperatures.
• reducing agents may be used in addition to the persulfate and peroxide initiators mentioned above.
• Typical reducing agents include but are not limited to: alkali metal salts of hydrosulfites, sulfoxylates, thiosulfates, sulfites, bisulfites, reducing sugars such as glucose, sorbose, ascorbic acid, erythorbic acid, and the like.
• the reducing agents are used at levels from about 0.01 pphm to about 5 pphm.
• the emulsifying agents are those generally used in emulsion polymerization.
• the emulsifiers can be anionic, cationic, surface-active compounds or mixtures thereof.
• the manner of combining the polymerization ingredients can be by various known monomer feed methods, such as, continuous monomer addition, incremental monomer addition, or addition in a single charge of the entire amounts of monomers.
• the entire amount of the aqueous medium with polymerization additives can be present in the polymerization vessel before introduction of the monomers, or alternatively, the aqueous medium, or a portion of it, can be added continuously or incrementally during the course of the polymerization.
• the aqueous dispersion according to the present invention further comprises surfactants.
• a surfactant is used in the aqueous dispersion it can be added before, at the same time as, or after the fatty acid or salt thereof.
• An optional surfactant can also be added before, at the same time as, or after the polymeric binder.
• the surfactant is chosen so that it does not adversely affect the coating. Cationic surfactants are less preferred. Examples of surfactants include but are not limited to phosphoric acid alkyl ester and diphosphonate surfactants, silicone based surfactants, fluorosurfactants, and salts thereof.
• a subject at least partly coated by contacting said substrate with an aqueous dispersion according to the present invention wherein said subject has an equilibrium contact angle higher than 120° degrees, preferably more than 135°, more preferably more than 150° for a drop of water on the surface.
• the subject is partly coated. In an alternative embodiment the subject is entirely coated.
• Precipitated calcium carbonate (Sturcal® F, Specialty Minerals Inc.®) (Particle size D 5 o ca 2.5 ⁇ m, apparent density 0.32-0.43 g/ml, and BET surface area ca 6 m 2 /g) (Aragonite content is minimum 50%) particles were mixed together with water and a sodium oleate solution in a glass beaker with a magnetic stirrer.
• the total content of calcium carbonate in water was 30 wt% and the content of sodium oleate was 1 wt% per pigment weight (dry on dry) . This suspension was mixed until it was essentially homogenous.
• Example 1 The formulation of Example 1 was modified by having 17 wt% per pigment of the same SB-latex binder (DL 940, The Dow Chemical Company®) instead of 30 wt% per pigment as used in Example 1.
• the coating and the analysis were performed as in Example 1.
• the contact angle was 145° and the normalized stain size was 2.5.
• Example 2 Dow Chemical Company® instead of 30 wt% per pigment.
• the coating and the analysis were performed as in Example 1.
• the contact angle was 146° and the normalized stain size was 0.9.
• Water droplets (9 ⁇ l) showed rolling at 20° inclination.
• Example 1 The formulation of Example 1 was modified by changing the pigment to another type of PCC calcium carbonate, Sturcal® H (Specialty Minerals Inc.®). (Particle size D 50 4.0 ⁇ m, apparent density 0.48-0.61 g/ml, and BET surface area ca 5 m 2 /g) (Aragonite content is minimum 50%) Further, the formulation in Example 1 was modified by adding 2 wt% per pigment of sodium oleate instead of 1 wt% per pigment as used in Example 1. The coating and the analysis were performed as in Example 1. For this coated object the contact angle was 153° and the normalized stain size was 0.6. Water droplets (9 ⁇ l) showed rolling at 5° inclination .
• Example 8 Example 8
• Example 9 The formulation of Example 8 was modified by increasing the total solids content of the coating from 34 wt% to 51 wt%. Otherwise the coating and analysis were performed as in Example 8. For this coated substrate the contact angle was 160° and the normalized stain size was 0.5. Water droplets (9 ⁇ l) showed rolling at 2.5° inclination.
• Example 8 The formulation of Example 8 was modified by adding commercially available ammonium zirconium crosslinker (Allicross® AZC-R, Allinova®) .
• the crosslinker content was 4 wt% dry based on dry binder weight. Otherwise the coating and analysis were performed as in Example 8.
• the contact angle was 141° and the normalized stain size was 0.6. Water droplets (9 ⁇ l) showed rolling at 15° inclination.
• Example 9 The formulation of Example 9 was modified by changing the binder to the commercially available latex Rhodopas Ultradia® 7100 (Rhodia®) .
• the binder content was 30 wt% per pigment weight (dry on dry) .
• the coating and analysis were performed as in Example 8. For this coated substrate the contact angle was 155° and the normalized stain size was 0.6. Water droplets (9 ⁇ l) showed rolling at 2.5° inclination .
• Ultradia® 7300 (Rhodia) .
• the binder content was again 30 wt% per pigment weight.
• the coating and analysis were performed as in Example 8.
• the contact angle was 154° and the normalized stain size was 0.6.
• Water droplets (9 ⁇ l) showed rolling at 10° inclination .
• Example 16 To the aqueous dispersion from Example 16, a styrene- butadiene latex binder (HPQ 73, Dow® Europe) was added, and the dispersion was stirred until homogeneous. The content of latex was 30 wt% per pigment weight (dry on dry) . The coating and the analysis were performed as in Example 16. For this coated substrate the contact angle was 113°.
• a styrene- butadiene latex binder HPQ 73, Dow® Europe
• HPQ 73 styrene-butadiene latex binder
• the coating and the analysis were performed as in Example 16. For this coated substrate the contact angle was 123°.
• Example 20 The formulation in Example 19 was modified by changing the ratio of PCC pigment to clay pigment to 50% PCC and 50% clay (dry on dry) .
• the coating and the analysis were performed as in Example 16.
• the contact angle was 115°.
• Example 1 The formulation of Example 1 was modified by having 2 wt% per pigment of sodium oleate instead of 1 wt% per pigment weight as used in Example 1. Further, the formulation in Example 1 was modified by having 30 wt% per pigment weight of another SB-latex binder (SHY-7, Dow® Europe) instead of DL 940.
• the aqueous dispersion was coated on paperboard (Cupforma Classic®, 230 g/m 2 , Stora Enso®) . The coating was performed using a bench coater from RK Print-Coat Instruments Ltd.® Several sheets of paper were coated and then dried in an oven at 90 0 C for 2 minutes. The coating and the analysis were performed as in Example 1. For this coated substrate the contact angle was 148° and the normalized stain size was 0.7. Water droplets (9 ⁇ l) showed rolling at 2.5° inclination.

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