FRICTION REDUCING COATINGS
An aqueous coating composition for reducing friction and/or blocking at a surface, said composition comprising a solid lubricant and a modified or synthetic clay mineral having thickening properties such that a 2% by weight aqueous dispersion of the modified or synthetic clay mineral thickener has a viscosity of at least 1000 mPa·s. Preferred clay minerals used as thickeners are preferably smectite clays such as saponite, hectorite, stevensite, sauconite, bentonite, beidellite, nontronite, or montmorillonite.
1 . An aqueous coating composition for reducing friction and/or blocking at a surface, the composition comprising a solid lubricant and a modified or synthetic clay mineral having thickening properties such that a 2% by weight aqueous dispersion of the modified or synthetic clay mineral thickener has a viscosity of at least 1000 mPa·s.
2 . An aqueous coating composition according to claim 1 , wherein the solid lubricant is a phyllosilicate.
3 . An aqueous coating composition according to claim 2 , wherein the solid lubricant is selected from mica, talc, kaolinite, sericite and chlorite.
4 . An aqueous coating composition according to claim 1 , wherein the solid lubricant is present at 3 to 40% by weight of the aqueous coating composition.
5 . An aqueous coating composition according to claim 1 , wherein the clay mineral thickener is saponite, bentonite or montmorillonite.
6 . An aqueous coating composition according to claim 5 , wherein the clay mineral thickener is modified by a water soluble organic polymer.
7 . An aqueous coating composition according to claim 6 , wherein the water soluble organic polymer contains carboxylate groups.
8 . An aqueous coating composition according to claim 7 , wherein the water soluble organic polymer is sodium polyacrylate or sodium polymethacrylate.
9 . An aqueous coating composition according to claim 7 , wherein the water soluble organic polymer is present at 0.1 to 40% by weight based on the clay mineral thickener.
10 . An aqueous coating composition according to claim 1 , wherein the clay mineral thickener is modified by treatment with an alkylalkoxysilane.
11 . An aqueous coating composition according to claim 1 , wherein the clay mineral thickener is artificial synthesized saponite.
12 . An aqueous coating composition according to claim 1 , wherein the modified or synthetic clay mineral thickener is present at from 0.2% to 5% by weight of the aqueous coating composition.
13 . An aqueous coating composition according to claim 1 , further comprising an organic polymer binder present in aqueous dispersion or a silicone binder in the form of a silicone based aqueous emulsion.
14 . An aqueous coating composition according to claim 13 , wherein the organic polymer binder comprises a polyurethane or acrylic-modified polyolefin present in aqueous emulsion.
15 . An aqueous coating composition according to claim 1 , further comprising a flame retardant.
16 . An aqueous coating composition according to claim 15 , wherein the flame retardant is aluminum trihydrate.
17 . A process for preparing an aqueous coating composition for reducing friction and/or blocking at a surface, the process comprising mixing water, a solid lubricant, and a modified or synthetic clay mineral thickener having thickening properties such that a 2% by weight aqueous dispersion of the modified or synthetic clay mineral thickener has a viscosity of at least 1000 mPa·s.
18 . A process according to claim 17 , wherein a water soluble organic polymer is premixed with the clay mineral to form a modified clay mineral thickener.
19 . A process according to claim 18 , wherein the clay mineral and water soluble organic polymer are premixed in water and dried.
20 - 21 . (canceled)
22 . An air bag coated with an anti-blocking coating comprising a solid lubricant and a modified or synthetic clay mineral having thickening properties such that a 2% by weight aqueous dispersion of the modified clay mineral thickener has a viscosity of at least 1000 mPa·s.
23 . A process of coating a substrate to reduce friction and/or blocking, wherein the substrate is coated with an aqueous coating composition comprising a solid lubricant and a modified or synthetic clay mineral having thickening properties such that a 2% by weight aqueous dispersion of the modified clay mineral thickener has a viscosity of at least 1000 mPa·s.
24 . A process according to claim 23 , wherein a fabric coated with an organic resin is top coated with the aqueous coating composition.
25 . An aqueous coating composition according to claim 13 , wherein the silicone binder has a dispersed phase, comprising a hydroxylated polydiorganosiloxane and an emulsifying agent, and an aqueous continuous phase, and optionally a silica reinforcing filler.