Coating composition comprising submicron calcium carbonate-comprising particles, process to prepare same and use of submicron calcium carbonate-comprising particles in coating compositions

Abstract

A coating composition comprising an aqueous dispersion of submicron natural ground calcium carbonate particles contained in a liquid binder, wherein the resultant coating may constitute either a clear coat or a glossing and opacifying coating, depending upon the presence of certain additives such as a mineral pigment (e.g., TiO 2 ). The composition is characterised in that comprises, in the case of a clear coating, at least one ground natural calcium carbonate having a median diameter of between 0.05 and 0.15 μm, while in the case of a glossing and opacifying coating, at least one ground natural calcium carbonate having a median diameter of between 0.05 and 0.3 μm and at least one pigment having a refractive index of greater than or equal to 2.5.

1 . A clear coat composition comprising an aqueous nanoparticle dispersion, wherein the nanoparticles are substantially dispersed and have a mean particle size D 50  of less than 1 micron, preferably of less than 500 nm, more preferably of less than 100 nm, and even more preferably of less than 50 nm. 
     
     
         2 . The clear coat composition according to  claim 1 , wherein the nanoparticles have a particle size D 90  of less than 1 micron, preferably of less than 500 nm, more preferably of less than 100 nm, and even more preferably of less than 50 nm. 
     
     
         3 . The clear coat composition according to  claim 1 , wherein the nitrogen BET surface area of the nanoparticles is greater than 20 m 2 /g, preferably greater than 30 m 2 /g, more preferably greater than 35 m 2 /g, and even more preferably about 40 m 2 /g. 
     
     
         4 . The clear coat composition according to  claim 1 , wherein the nanoparticles are selected from the group comprising calcium carbonate, other alkali and earth-alkali carbonates including Li 2 CO 3 , BeCO 3 , MgCO 3 , SrCO 3 , BaCO 3 , and RaCO 3 ; carbonates of Fe(II), Fe(III), Mn(II), Zn, Ag, Hg(I), Hg(II), Cu(II), Pb(II), Bi(III); silicates of Ba, Ca, Mg, Al, Cr(III), Fe(II), Fe(III), Mn(II), Zn, Ag, Cu(II), Pb(II); sulfides of Fe(II), Mn(II), Zn, Ag, Hg(I), Hg(II), Cu(II), Pb(II), Bi(III), Sn(II); oxides and hydroxides of the above metals; hydroxyapatite; organic compounds including 1,8-bis-(dimethylamino)naphthalene, 1,8-bis(hexamethyltriaminophosphazenyl)naphthalene and 2,6-di-tert-butylpyridine; or any combination of the aforementioned. 
     
     
         5 . The clear coat composition according to  claim 4 , wherein the calcium carbonate is either a ground calcium carbonate derived from grinding of chalk, limestone, marble, or is precipitated calcium carbonate, and preferably is ground calcium carbonate, and more preferably is submicron ground calcium carbonate (SMGCC). 
     
     
         6 . The aqueous nanoparticle dispersion according to  claim 1 , wherein the nanoparticles are dispersed in at least one binder including vinyl-acrylic, styrene-acrylic, acrylic dispersions, solution acrylics, alkyds, polyurethanes dispersed either in water or solvent, polymers containing ester groups including polyesters, polyester-based polyurethanes, polyester-based polyureas and polyester-based polyamides, preferably the binder is a polyester-polyurethane polymer binder. 
     
     
         7 . The clear coat composition according to  claim 1 , wherein the substantially dispersed nanoparticles contained in the coating composition have a D 98  particle size of ≦350 nm, preferably ≦300 nm, and a D 50  particle size of ≦200 nm, preferably ≦150 nm. 
     
     
         8 . A glossing and opacifying coating composition comprising an aqueous nanoparticle dispersion, wherein the nanoparticles are substantially dispersed and have a mean particle size D 50  of less than 1 micron, preferably of less than 500 nm, more preferably of less than 100 nm, and even more preferably of less than 50 nm. 
     
     
         9 . The glossing an opacifying coating composition according to  claim 8 , wherein the nanoparticles have a particle size D 90  of less than 1 micron, preferably of less than 500 nm, more preferably of less than 100 nm, and even more preferably of less than 50 nm. 
     
     
         10 . The glossing an opacifying coating composition according to  claim 8 , wherein the nitrogen BET surface area of the nanoparticles is greater than 20 m 2 /g, preferably greater than 30 m 2 /g, more preferably greater than 35 m 2 /g, and even more preferably about 40 m 2 /g. 
     
     
         11 . The glossing an opacifying coating composition according to  claim 8 , wherein the nanoparticles are selected from the group comprising calcium carbonate, other alkali and earth-alkali carbonates including Li 2 CO 3 , BeCO 3 , MgCO 3 , SrCO 3 , BaCO 3 , and RaCO 3 ; carbonates of Fe(II), Fe(III), Mn(II), Zn, Ag, Hg(I), Hg(II), Cu(II), Pb(II), Bi(III); silicates of Ba, Ca, Mg, Al, Cr(III), Fe(II), Fe(III), Mn(II), Zn, Ag, Cu(II), Pb(II); sulfides of Fe(II), Mn(II), Zn, Ag, Hg(I), Hg(II), Cu(II), Pb(II), Bi(III), Sn(II); oxides and hydroxides of the above metals; hydroxyapatite; organic compounds including 1,8-bis-(dimethylamino)naphthalene, 1,8-bis(hexamethyltriaminophosphazenyl)naphthalene and 2,6-di-tert-butylpyridine; or any combination of the aforementioned. 
     
     
         12 . The glossing an opacifying coating composition according to  claim 11 , wherein the calcium carbonate is either a ground calcium carbonate derived from grinding of chalk, limestone, marble, or is precipitated calcium carbonate, and preferably is ground calcium carbonate, and more preferably is submicron ground calcium carbonate (SMGCC). 
     
     
         13 . The glossing an opacifying coating composition according to  claim 8 , wherein the nanoparticles are dispersed in at least one binder including vinyl-acrylic, styrene-acrylic, acrylic dispersions, solution acrylics, alkyds, polyurethanes dispersed either in water or solvent, polymers containing ester groups including polyesters, polyester-based polyurethanes, polyester-based polyureas and polyester-based polyamides, preferably the binder is a polyester-polyurethane polymer binder. 
     
     
         14 . The glossing an opacifying composition according to  claim 8 , having a pigment volume concentration (PVC) of from 5% up to the critical pigment volume concentration (CPVC) and comprising at least one ground calcium carbonate having a D 50  (Mal) of between 0.05 and 0.3 μm, and at least one pigment having a refractive index of greater than or equal 2.5. 
     
     
         15 . The glossing an opacifying composition according to  claim 14 , wherein the ground calcium carbonate has a D 50  (Mal) of between 0.1 and 0.3 μm. 
     
     
         16 . The glossing an opacifying composition according to  claim 8 , wherein the ground calcium carbonate has a D 98 /D 50  (Mal) of greater than 3. 
     
     
         17 . The glossing an opacifying composition according to  claim 16 , wherein the ground calcium carbonate has a D 98  of less than or equal to 1 μm, preferably of less than or equal to 0.6 μm, more preferably of less than or equal to 0.4 μm. 
     
     
         18 . The glossing an opacifying composition according to  claim 8 , wherein the ground calcium carbonate has a refraction index of approximately 1.5 to 1.7. 
     
     
         19 . The glossing an opacifying composition according to  claim 14 , wherein the pigment having a refractive index of greater than or equal 2.5 is selected from one or more of the following: titanium dioxide and/or zinc sulphide and/or zinc oxide, and preferably is titanium dioxide. 
     
     
         20 . The glossing an opacifying composition according to  claim 19 , wherein the pigment having a refractive index of greater than or equal 2.5 is titanium dioxide and the titanium dioxide:ground calcium carbonate weight ratio is of 70:30 to 98:2, more preferably the titanium dioxide:ground calcium carbonate weight ratio is of 85:15 to 90:10. 
     
     
         21 . A method of forming a clear coat composition, wherein water, nanoparticles and at least one binder are combined and then dispersed in order to form the clear coat composition. 
     
     
         22 . The method according to  claim 21 , wherein the nanoparticles are dispersed with one or more dispersants. 
     
     
         23 . A method of forming a glossing and opacifying composition wherein:
 a) at least one ground calcium carbonate having a D 50  (Mal) of between 0.05 and 0.3 μm is provided,   b) at least one pigment having a refractive index of greater than or equal 2.5 is provided,   c) at least one binder is provided,   d) the ground calcium carbonate of step a) is mixed with the pigment of step b) and the binder of step c).   
     
     
         24 . A substrate comprising the clear coat composition according to  claim 1 . 
     
     
         25 . A coated substrate coated with a clear coat composition according to  claim 1 . 
     
     
         26 . The coated substrate according to  claim 24 , wherein the substrate is selected from porous and non-porous substrates including papers, non-woven materials, textiles, leather, wood, concrete, masonry, metals, house wrap and other building materials, fiberglass, polymeric articles, personal protective equipment, carpets, textiles used in clothing, upholstery, tents, awnings, air bags, fabrics, yarns, and blends, whether woven, non-woven, or knitted, and whether natural, synthetic, or regenerated. 
     
     
         27 . The coated substrate according to  claim 24 , wherein the coated substrate includes papers and non-wovens, fibrous materials, films, sheets, composites inks, printing binders, flock and other adhesives, and personal hair products including skin care, hair care, and nail care products, livestock and feed applications. 
     
     
         28 . The coated substrate according to  claim 24 , wherein the coating composition is applied to the substrate in an amount so as to form a layer having a thickness of between 100 and 400 nm. 
     
     
         29 . A substrate comprising the glossing and opacifying composition according to  claim 8 . 
     
     
         30 . A coated substrate coated with a glossing and opacifying composition according to  claim 8 . 
     
     
         31 . The coated substrate according to  claim 30 , wherein the substrate is selected from porous and non-porous substrates including papers, non-woven materials, textiles, leather, wood, concrete, masonry, metals, house wrap and other building materials, fiberglass, polymeric articles, personal protective equipment, carpets, textiles used in clothing, upholstery, tents, awnings, air bags, fabrics, yarns, and blends, whether woven, non-woven, or knitted, and whether natural, synthetic, or regenerated. 
     
     
         32 . The coated substrate according to  claim 30 , wherein the coated substrate includes papers and non-wovens, fibrous materials, films, sheets, composites inks, printing binders, flock and other adhesives, and personal hair products including skin care, hair care, and nail care products, livestock and feed applications. 
     
     
         33 . The coated substrate according to  claim 30 , wherein the coating composition is applied to the substrate in an amount so as to form a layer having a thickness of between 100 and 400 nm. 
     
     
         34 . The coated substrate according to  claim 30 , wherein the glossing and opacifying coating composition provides a gloss measured at 60° of greater than 70% and an opacity of greater than 97%. 
     
     
         35 . A method of forming a coated substrate coated with a clear coat composition, wherein a clear coat composition according to  claim 1  is applied to the substrate, preferably by coating, impregnating or otherwise treating. 
     
     
         36 . The method according to  claim 25 , wherein the coating composition is applied to the substrate in an amount so as to form a layer having a thickness of between 100 and 400 nm. 
     
     
         37 . The method according to  claim 35 , wherein the coated substrate is further dried and optionally cured. 
     
     
         38 . A method of forming a coated substrate coated with a glossing and opacifying composition, wherein a glossing and opacifying composition according to  claim 8  is applied to the substrate preferably by coating, impregnating or otherwise treating. 
     
     
         39 . The method according to  claim 38 , wherein the coating composition is applied to the substrate in an amount so as to form a layer having a thickness of between 100 and 400 nm. 
     
     
         40 . The method according to  claim 38 , wherein the coated substrate is further dried and optionally cured. 
     
     
         41 . A colloidally stable aqueous dispersion comprising water, a polyester-polyurethane polymer binder and a plurality of substantially dispersed submicron natural ground calcium-carbonate comprising particles. 
     
     
         42 . A composition comprising a binder containing submicron natural ground calcium-carbonate comprising particles in a substantially dispersed form.