Patent DE-102008008934-B3 (DE)
Title: Coated split leather such as cattle-hide split leather for special shoes, interior design of boats and sanitary and hospital equipments, comprises fine to coarse-grained nubuck-like appearing surface structure
Inventor: SCHAEFER PHILIPP
IPC: C14C11/00
Filed: 2008-02-13
Granted: 2009-10-29
Abstract: The coated split leather such as cattle-hide split leather (1) comprises fine to coarse-grained nubuck-like appearing surface structure. The surface of the leather is provided and/or coated with a moisture-tight and water-tight coating (5) on an outer side and/or an upper side. The coating is formed on basis of polymer and has a connecting layer (2), a middle layer (3) and a finishing layer (4), which are made of an aqueous plastic dispersion predominantly containing polyurethane. The coating is formed with the finishing layer on hot free-silicone base made of tin and/or tinorganic compounds. The coated split leather such as cattle-hide split leather (1) comprises fine to coarse-grained nubuck-like appearing surface structure. The surface of the leather is provided and/or coated with a moisture-tight and water-tight coating (5) on an outer side and/or an upper side. The coating is formed on basis of polymer and has a connecting layer (2), a middle layer (3) and a finishing layer (4), which are made of an aqueous plastic dispersion predominantly containing polyurethane. The coating is formed with the finishing layer on a hot free silicone base made of tin and/or tinorganic compounds and/or a matrix, is formed with the middle layer, which is formed on, bonded with and finally arranged below the finishing layer, and is formed with the connecting layer, which is applied on the leather and is bonded with the middle layer. The tin-free finishing layer that is formed with a polymer containing silicone polymer and/or silicone additive is formed with several cavities, hollow channels, capillaries, pores, openings and/or recesses, concavities and slots starting on its side turned to the middle layer, completely penetrating up to their outer side and/or surface and/or ending within the finishing layer. The cavities, hollow channels, capillaries, pores, openings and/or recesses, concavities and slots, at whose inner walls are filled with single-piece shaped-bodies and/or filling bodies, stalagmites, pins, rods, cylinders and cones completely bonding with the polymer material of the middle layer, penetrate and seal with in the finishing layer and have a small interior width. The silicone base and/or the matrix is structured with elevations in a nubuck-like manner. The finishing layer is formed with polyurethane, and has an external surface formed by negative nubuck-like embossment. The single-piece shaped-bodies and/or filling bodies, stalagmites, pins, rods, cylinders and cones filling the cavities, hollow channels, capillaries, pores, openings and/or recesses, concavities and slots are anchored at their inner walls. The coating is fixed bonded over its connecting layer and is inseparably bonded with the polished split leather. The polyurethane material identical with the polyurethane material of the middle layer is penetrated into the cavities, hollow channels, capillaries, pores and/or openings, recesses and slots and completely fills the same, so that the cavities passing through into the shape-filling bodies and/or beginning in lower side and ending within the same or passing through up to the surface of the finishing layer is completely penetrated and wall-anchored to the shaped- and/or filling bodies filling the cavities of the finishing layer and shape-filling bodies made of polyurethane material identical with the polyurethane material of the connecting layer. The cavities, hollow channels, capillaries, pores, openings, recesses and slots filled with polyurethane material of the middle layer are present in the finishing layer per cm 2>of 18-5. The air-tight and water-tight coating comprising three layers has a layer thickness of 0.12 mm and possesses no water vapor permeability. The middle layer and the connecting layer bonding with the middle layer and the leather surface mutually have a high layer thickness (dmv) than the finishing layer. The thickness of the finishing layer is 30-45% and a common thickness of the middle layer and the connecting layer is 70-55% related to the total thickness of the coating. The polyurethane material of the middle layer and the connecting layer contains no silicone- and fluoropolymer, and have same compositions and/or initial molecular sizes. The finishing layer has any surface structure or embossing structure and/or appearance and grip of the leather with a microscopic rough surface with elevations and recesses of 0.005-0.02 mm. The finishing layer has a circular- and/or hollow-cellular surface structure formed from the silicone matrix provided for the arrangement of its outer surface and/or surface and the pores and formed of foamed rubber transferring it during polishing the leather. A coating made of a silicone rubber formed with an aqueous silicone emulsion with particles with a size in nanometer range is applied on the surface of the finishing layer preventing contamination and/or improvement in creaking behavior and/or fire-retardant, where the coating has a thickness of 0.005 mm. High molecular silicones introduced over an emulsion next to less solid silicone and/or polysiloxane particles with the characteristics of the soft rubber are applied in the finishing layer formed from a dispersion made of a medium-hard branched polyurethane and then formed with reinforced and/or cross-linked polyurethane. The middle layer is formed from the reinforced and/or cross-linked polyurethane dispersion, which has thermoplastic characteristics before cross-linking, an unbranched and/or linear structure and high adhesive properties. The middle layer and/or the connecting layer contains micro-hollow spheres with a volume portion of less than 10%. Each of the layers forming the coating of the split leather is kept free from tin and/or tin compounds.