Adhesive and sealant systems

1. Adhesive and sealant composition comprising a member selected from the group consisting of polyurethane, unsaturated polyester resins, vinyl ester resins, acrylates, polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, ethylene vinyl acetate, ethylene-acrylic acid copolymers, polyvinyl acetates, polyvinyl chloride, chloroprene rubber, nitrile rubber, butyl rubber, polysulfide, fluorinated hydrocarbons saturated polyesters and copolyesters, urea-formaldehyde resins, melamine-formaldehyde resins, polyimides, polybenzimidazoles, and polysulfones, containing 1 wt. % to 15 wt. % of a compacted hydrophobic, pyrogenic silica having a compacted bulk density of 60 g/l to 200 g/l, a BET surface area of 80 to 290 m 2 /g and a carbon content of 1.0 to 6.5 wt. %, wherein the silica has been compacted by a pressing filter belt and as a result of said silica being compacted in such way said adhesive and sealant composition is rendered thixotropic and the time required for incorporating said compacted hydrophobic pyrogenic silica into said adhesive and sealant composition is reduced compared to the time required for incorporation into said composition of silica that has not been compacted by a pressing filter belt, and wherein the silica has been made hydrophobic with a silicone oil, with an octyl silane, with hexadimethyl disilazane, with a methacrylate silane, or with an octamethyl cyclotetrasiloxane.

2. A method for reducing the time needed to incorporate compacted hydrophobic silicas into adhesives and sealant compositions in order to render them thixotropic comprising incorporating a compacted hydrophobic silica in the amount of 1 wt % to 15 wt % into a member selected from the group consisting of polyurethane, unsaturated polyester resins, vinyl ester resins, acrylates, polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, ethylene vinyl acetate, ethylene-acrylic acid copolymers, polyvinyl acetates, polyvinyl chloride, chloroprene rubber, nitrile rubber, butyl rubber, polysulfide, fluorinated hydrocarbons saturated polyesters and copolyesters, urea-formaldehyde resins, melamine-formaldehyde resins, polyimides, polybenzimidazoles, and polysulfones, wherein the compacted hydrophobic silica has a compacted bulk density of 60 g/l to 200 g/l, a BET surface area of 80 to 290 m 2 /g and a carbon content of 1.0 to 6.5 wt. %, and wherein the silica has been compacted by a pressing filter belt and as a result of said silica being compacted in such way said adhesive and sealant compositions are rendered thixotropic and the time required for incorporating said compacted hydrophobic pyrogenic silica into said adhesive and sealant compositions is reduced compared to the time required for incorporation into such compositions of silica that has not been compacted by a pressing filter belt, and wherein the silica has been made hydrophobic with a silicone oil, with an octyl silane, with hexadimethyl disilazane, with a methacrylate silane, or with an octamethyl cyclotetrasiloxane.

3. The method according to claim 2 wherein the time needed to prepare thixotropic adhesives and sealants is shorter than would be the time required to prepare thixotropic adhesives and sealants using compacted hydrophobic silica having a compacted bulk density of 50 g/l.

4. The adhesive and sealant composition according to claim 1 wherein the silica is selected from the group consisting of

5. The method according to claim 2 wherein the silica is selected from the group consisting of