Grease Resistant Coating For Fibrous Materials
Grease resistant coatings for fibrous materials, particularly paper and the like used for packaging but also nonwoven, woven or knitted textile materials.
1 . An aqueous coating composition comprising dissolved polyvinyl alcohol and an emulsified organosilicon material, wherein the composition contains a saccharide of molecular weight below 2000.
2 . A composition according to claim 1 , wherein the saccharide is a monosaccharide containing a carboxylic acid group.
3 . A composition according to claim 2 , wherein the monosaccharide is gluconic acid.
4 . A composition according to claim 1 , wherein the weight ratio of saccharide to polyvinyl alcohol is in the range 1:2 to 1:50.
5 . A composition according to claim 1 , wherein the weight ratio of polyvinyl alcohol to organosilicon material is in the range from more than 2:1 up to 20:1.
6 . An aqueous coating composition according to claim 1 , wherein the composition is free from any surfactant other than the polyvinyl alcohol.
7 . An aqueous coating composition comprising dissolved polyvinyl alcohol and an emulsified organosilicon material, wherein the weight ratio of polyvinyl alcohol to organosilicon material is in the range from more than 2:1 up to 20:1 and the composition is free from any surfactant other than the polyvinyl alcohol.
8 . A composition according to claim 1 , wherein the organosilicon material is a curable organopolysiloxane composition.
9 . A composition according to claim 8 , wherein the curable organopolysiloxane composition comprises an organopolysiloxane containing alkenyl groups, an organopolysiloxane containing Si—H groups and a hydrosilylation catalyst.
10 . A composition according to claim 1 , wherein the organosilicon material is a silane or polysiloxane capable of reacting with cellulose.
11 . A composition according to claim 1 , wherein the organosilicon material is a material which dries to form a hydrophobic film without reaction.
12 . (canceled)
13 . (canceled)
14 . (canceled)
15 . A process for the preparation of a coating composition, wherein an organosilicon material is mixed with an aqueous solution of polyvinyl alcohol in the absence of any surfactant, the mixture is homogenised to form an emulsion and optionally further aqueous polyvinyl alcohol solution is mixed with the emulsion after homogenisation, the weight ratio of polyvinyl alcohol to organosilicon material in the final composition being in the range from more than 2:1 up to 20:1.
16 . A process according to claim 15 , wherein a composition (A) comprising an organopolysiloxane containing alkenyl groups and an organopolysiloxane containing Si—H groups and a composition (B) comprising an organopolysiloxane containing alkenyl groups and a hydrosilylation catalyst are separately mixed with an aqueous solution of polyvinyl alcohol and separately homogenised to form an emulsion, and the emulsion of composition (A) and the emulsion of composition (B) thereby formed are mixed with each other and optionally with further polyvinyl alcohol solution.
17 . A process for the preparation of a coating composition in which an organosilicon material is mixed with an aqueous solution of polyvinyl alcohol and the mixture is homogenised to form an emulsion, wherein a saccharide of molecular weight below 2000 is mixed with the organopolysiloxane composition and the aqueous polyvinyl alcohol solution, either before or after homogenisation.
18 . A process according to claim 17 , wherein further aqueous polyvinyl alcohol solution is mixed with the emulsion after homogenisation.
19 . A process according to claim 17 , wherein a composition (A) comprising an organopolysiloxane containing alkenyl groups and an organopolysiloxane containing Si—H groups and a composition (B) comprising an organopolysiloxane containing alkenyl groups and a hydrosilylation catalyst are separately mixed with an aqueous solution of polyvinyl alcohol and separately homogenised to form an emulsion, and the emulsion of composition (A) and the emulsion of composition (B) thereby formed are mixed with each other and optionally with further polyvinyl alcohol solution, wherein the saccharide of molecular weight below 2000 is mixed with composition (A) and/or composition (B) either before or after homogenisation, or with the mixture of the emulsion of composition (A) and the emulsion of composition (B).
20 . A process for treating a fibrous substrate to enhance its grease resistance, wherein a composition according to claim 1 is applied to the fibrous substrate and is dried on the substrate.
21 . A fibrous substrate coated with a composition according to claim 1 .
22 . A process for treating a fibrous substrate to enhance its grease resistance, wherein a composition according to claim 6 is applied to the fibrous substrate and is dried on the substrate.
23 . A fibrous substrate coated with a composition according to claim 6 .