Coating composition comprising submicron calcium carbonate
Coating composition providing gloss and opacity on application, having a pigment volume concentration of from 5% up to the critical pigment volume concentration and characterised in that comprises at least one ground natural calcium carbonate having a volume 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 glossing and opacifying coating composition comprising:
(i) at least one submicron ground natural calcium carbonate (SMGCC) having a volume median particle diameter d 50 of 0.05 to 0.3 μm and a d 98 of less than or equal to 0.6 μm, and titanium dioxide, wherein the titanium dioxide: SMGCC weight ratio in the composition is from 75:25 to 98:2, and wherein the calcium carbonate is calcite, marble, chalk or limestone; and
(ii) glossing and opacifying coating composition components,
wherein the glossing and opacifying coating composition has a pigment volume concentration (PVC) of from 5 vol.-% up to a critical pigment volume concentration (CPVC),
and wherein the glossing and opacifying coating composition, applied to a contrast card to form a layer having a thickness of 150 μm or 300 μm, has a gloss that is within ±3% of the gloss of the same composition and thickness in which the SMGCC is fully replaced with the titanium dioxide, when gloss is measured either at a 60° or an 85° incident angle according to DIN 67530.
2. The glossing and opacifying coating composition according to claim 1 , having a PVC of from 10 to 30 vol.-%.
3. The glossing and opacifying coating composition according to claim 1 , having a PVC of from 15 to 25 vol.-%.
4. The glossing and opacifying coating composition according to claim 1 , having a PVC of from 17 to 21 vol.-%.
5. The glossing and opacifying coating composition according to claim 1 , wherein the SMGCC has a volume median diameter d 50 of 0.08 to 0.3 μm.
6. The glossing and opacifying coating composition according to claim 1 , wherein the SMGCC has a volume median diameter d 50 of 0.1 to 0.2 μm.
7. The glossing and opacifying coating composition according to claim 1 , wherein the SMGCC has a d 98 /d 50 of greater than 3.
8. The glossing and opacifying coating composition according to claim 1 , wherein the SMGCC has a d 98 of less than or equal to 0.4 μm.
9. The glossing and opacifying coating composition according to claim 1 , wherein the titanium dioxide: SMGCC weight ratio is from 75:25 to 90:10.
10. The glossing and opacifying coating composition according to claim 1 , wherein the titanium dioxide: SMGCC weight ratio is from 80:20 to 85:15.
11. The glossing and opacifying coating composition according to claim 1 , which is paint.
12. The glossing and opacifying coating composition according to claim 1 , wherein the glossing and opacifying coating composition components comprise a resin, and the resin is a latex or an acrylate-based binder.
13. The glossing and opacifying coating composition according to claim 1 , further comprising one or more additives selected from the group consisting of defoamers, levelling agents, flatting agents, preservatives, optical brighteners, light stabilizers, thickeners, dispersents, solvents, water, coalescing solvents, plasticizers, anti-settling agents, dispersants, surfactants, rheology modifiers, biocides, metals, UV-absorbers, stabilizers, zinc oxide, nepheline syenite, diatomaceous earth, aluminium silicates, quartz, mica, wollastonite, colored inorganic pigments, colored organic pigments, and fillers.
14. The glossing and opacifying coating composition according to claim 1 , wherein the SMGCC is dispersed with one or more dispersants.
15. The glossing and opacifying coating composition according to claim 1 , having a Brookfield viscosity of from 200 to 500 mPas when measured at a rotation speed of 100 rpm at room temperature.