Use of an aqueous coating composition for the manufacture of surface coatings of seals
The invention relates to the use of an aqueous coating composition, comprising a film forming binder system, containing at least one crosslinkable resin and optionally at least one crosslinking agent, and spherical particles comprising a polyalkylsiloxane having R—SiO 3/2 groups (e.g. silsesquioxane) for the manufacture of surface coatings of seals, a process for the manufacture of coated seals, and the coated seals obtained by such process.
1 . Use of an aqueous coating composition, comprising
a film forming binder system, containing at least one crosslinkable resin and optionally at least one crosslinking agent, and
spherical particles of at least one polyalkylsiloxane comprising R 1 —SiO 3/2 groups, whereby R 1 is C1-C18 alkyl, and/or spherical particles of at least one polysiloxane which are coated with at least one polyalkylsiloxane comprising R 1 —SiO 3/2 groups, whereby R 1 is C1-C18 alkyl, for the manufacture of surface coatings of seals.
2 . Use of an aqueous coating composition according to claim 1 , wherein the crosslinkable resin is selected from the group of polyester, polyether, polyesterether, polycarbonate, polyamide, polyesteramide, polyacrylate, and polyurethane each of which optionally may comprise segments of different polymeric groups.
3 . Use of an aqueous coating composition according to claim 1 or 2 , wherein the crosslinkable resin is a polyurethane which optionally comprises segments of polyester, polyether, polycarbonate and polyesteramide and having crosslinkable functional groups.
4 . Use according to claim 3 , wherein the crosslinkable functional groups are selected from the group consisting of active hydrogen containing functional groups, olefinically unsaturated groups, isocyanate groups and epoxy groups.
5 . Use according to claim 4 , wherein the crosslinkable functional groups are active hydrogen containing functional groups selected from hydroxyl and amino groups.
6 . Use according to any of claims 1 to 5 , wherein the crosslinking agent is selected from the group consisting of blocked or unblocked polyisocyanate, polyepoxides, aminoplasts, phenol/formaldehyde adducts, carbamates, compounds having at least two cyclic carbonate groups, polyols and polyanhydrides.
7 . Use according to any of claims 1 to 6 , wherein the crosslinkable resin is a polyol and/or polyamine and the crosslinking agent is a polyisocyanate.
8 . Use according to any of claims 1 to 7 , wherein the spherical particles of polyalkylsiloxane consist of a crosslinked polyalkylsiloxane prepared by the hydrolysis, condensation, polymerisation and/or crosslinking of alkylsilanes or alkylsiloxanes.
9 . Use according to any of claims 1 to 8 , wherein the spherical particles have a softening point which is at least 50° C. higher than the curing temperature of the coating composition.
10 . Use according to any of claims 1 to 9 , wherein the polyalkylsiloxane is polymethylsilsesquioxane.
11 . Use according to any of claims 1 to 10 , wherein the particle size of the spherical particles is from about 1 to about 20 μm.
12 . Use according to any of claims 1 to 11 , wherein the spherical particles essentially have no functional groups reactive with the binder system on the surface thereof.
13 . A process for the manufacture of seals having a surface coating, which comprises:
preparing an aqueous coating composition as defined in any of claims 1 to 12 ,
applying said aqueous coating composition onto the surface of a seal substrate, and
forming a film from said aqueous coating composition onto said substrate to obtain the surface-coated seal.
14 . A process for the manufacture of seals coated with a polyurethane-containing surface coating according to claim 13 , which comprises:
preparing a first component by mixing at least one polyisocyanate or a composition thereof or at least one polyol and/or polyamine or a composition thereof with said spherical particles,
subsequently mixing said first component with either at least one polyisocyanate or a composition thereof or at least one polyol and/or polyamine or a composition thereof to obtain an aqueous coating composition,
applying said aqueous coating composition on the surface of a seal substrate, and
forming a film from said aqueous coating composition onto said substrate to obtain the surface-coated seal.
15 . The process according to claim 14 , which comprises mixing at least one polyol and/or polyamine or a composition thereof with said spherical particles and subsequently mixing the composition obtained with at least one polyisocyanate or a composition thereof.
16 . The process according to any of claims 13 to 15 , wherein the seal substrates are shaped articles, which are elastomeric at room temperature.
17 . Sealant comprising the aqueous coating composition as defined in any of claims 1 to 12 which has been cured onto a sealant substrate.
18 . Use of the sealants according to claim 17 for sealing of movable parts.