Sheet-like products exhibiting oleophobic and hydrophobic properties
View Patent ↗A method of manufacturing a cellulosic sheet having at least one of hydrophobic and oleophobic properties comprises the steps of depositing a stock of cellulosic fibers onto at least one forming fabric at an impingement zone and forming a web therefrom in a formation process; combining a water-based composition comprising an adhesion promoter, an organic nanoparticulate polymer and a fluorocarbon with the web at a preselected combination stage prior to a heating stage at which the web is subjected to a temperature exceeding 60° C.; and heat-curing the composition with the web during a drying process. A water-based composition for imparting at least one of hydrophobic and oleophobic properties to a cellulosic sheet during manufacture comprises an adhesion promoter, an organic nanoparticulate polymer and a fluorocarbon. A cellulosic sheet or layer thereof has at least one of hydrophobic and oleophobic properties. Improved resistance of cellulosic sheets to oil or water is obtained.
1. A method of manufacturing a cellulosic sheet having at least one of hydrophobic and oleophobic properties, the method comprising
(i) depositing a stock of cellulosic fibres onto at least one forming fabric at an impingement zone and forming a web therefrom in a formation process;
(ii) combining a water-based composition comprising an adhesion promoter, an organic nanoparticulate polymer and a fluorocarbon with the web at a preselected combination stage prior to a heating stage at which the web is subjected to a temperature exceeding 60° C., wherein in the water-based composition the adhesion promoter is an organofunctional silane, the organic nanoparticulate polymer is selected from nanowaxes of polyethylene or polypropylene, and prepolymers of a condensated silane, and the fluorocarbon is selected from the group consisting of a fluoroacrylate and a fluoralkyl-polyurethane copolymer; and
(iii) heat-curing the composition with the web during a drying process.
2. A method as claimed in claim 1 , wherein the water-based composition is combined with the web by coating at least one side of the web during the formation process.
3. A method as claimed in claim 1 , wherein the water-based composition is combined with the web by addition to the stock prior to the deposit at the impingement zone.
4. A method as claimed in claim 3 , wherein solids of the water-based composition after addition to the stock are present in the stock in a range of 0.001% to 1%.
5. A method as claimed in claim 4 , comprising the further step of incorporating at least one of the sheets into a multi-layered cellulosic sheet.
6. A method as claimed in claim 1 , wherein the functional group of the organofunctional silane is selected from the group consisting of vinyl-, epoxy-, amino-, mercapto- and methacrylate.
7. A method as claimed in claim 1 , wherein in the water-based composition the adhesion promoter is present in a range of between 10% and 25%, the organic nanoparticulate polymer is present in a range of between 10% and 25%, and the fluorocarbon is present in the range of between 30% and 70% by weight.
8. A method as claimed in claim 1 , wherein the condensated silane is selected from the group consisting of methyltriethoxysilane, propyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane and phenyltrimethoxysilane.
9. A method as claimed in claim 1 , wherein the step of heat-curing is conducted at a temperature in a range between 60° C. and 210° C.
10. A method as claimed in claim 1 , wherein the step of heat-curing is conducted at a temperature in a range between 100° C. and 200° C.
11. A cellulosic sheet having at least one of hydrophobic and oleophobic properties, and being manufactured as a web from a stock of cellulosic fibres wherein the web is combined with a water-based composition comprising an adhesion promoter, an organic nanoparticulate polymer and a fluorocarbon, wherein the adhesion promoter is an organofunctional silane, the organic nanoparticulate polymer is selected from the group consisting of nanowaxes of polyethylene or polypropylene, and prepolymers of a condensated silane, and the fluorocarbon is selected from the group consisting of a fluoroacrylate and a fluoralkyl-polyurethane copolymer.
12. A cellulosic sheet as claimed in claim 11 , wherein the water-based composition is combined into the stock.
13. A cellulosic sheet as claimed in claim 11 , wherein the water-based composition is coated onto the web.
14. A cellulosic sheet as claimed in claim 11 , wherein the functional group of the organofunctional silane is selected from the group consisting of vinyl-, epoxy-, amino-, mercapto- and methacrylate.
15. A cellulosic sheet as claimed in claim 11 , wherein the condensated silane is selected from the group consisting of methyltriethoxysilane, propyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane and phenyltrimethoxysilane.
16. A cellulosic sheet as claimed in claim 11 , wherein in the water-based composition the adhesion promoter is present in a range of between 10% and 25%, the organic nanoparticulate polymer is present in a range of between 10% and 25%, and the fluorocarbon is present in the range of between 30% and 70% by weight.
17. A multi-layer cellulosic sheet having at least one of hydrophobic and oleophobic properties, at least one layer being manufactured as a web from a stock of cellulosic fibres wherein the web is combined with a water-based composition comprising an adhesion promoter, an organic nanoparticulate polymer and a fluorocarbon, wherein the adhesion promoter is an organofunctional silane, the organic nanoparticulate polymer is selected from the group consisting of nanowaxes of polyethylene or polypropylene, and prepolymers of a condensated silane, and the fluorocarbon is selected from the group consisting of a fluoroacrylate and a fluoralkyl-polyurethane copolymer.