摘要:
Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 150±15 m2/g, wherein the aggregates display an average surface area of 12000 to 20000 nm2, an average equivalent circle diameter (ECD) of 90 to 120 nm and an average circumference of 1150 to 1700 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a second silicon component comprising H3SiCl, H2SiCl2, HSiCl3, CH3SiCl3, (CH3)2SiCl2, (CH3)3SiCl and/or (n-C3H7)SiCl3 are mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1670 to 1730° C. is obtained. Silicone sealing compound containing the pyrogenically produced silicon dioxide powder.
摘要:
A room temperature crosslinking, one component (RTV 1C) silicone rubber formulation with hydrophobic, silica featuring extremely low water absorption, a high level of whiteness, and fine-tunable, storage-stable rheological properties with a high reinforcing action in the silicone rubber vulcanizate contains A) from 0.5 to 60% by weight of a hydrophobic silica having the following properties: a carbon content of >3.1%; a methanol wettability of >60%; a reflectance of >94%; a BET/CTAB ratio of from >1 to 30 m2/g; a water vapor absorption at 30° C. at an ambient humidity of 30 of
摘要:
Preparation of 2,3,5-trimethylhydroquinone diesters by rearrangement of 2,6,6-trimethylcyclohex-2-ene-1,4-dione (4-oxo-isophorone, ketoisophorone) in the presence of a solid, acid catalyst and an acylating agent, for example carboxylic acid anhydrides or carboxylic acid halides. The 2,3,5-trimethylhydroquinone diester may then optionally be saponified to the free 2,3,5-trimethylhydroquinone, which is a valuable building block in the synthesis of vitamin E.
摘要:
Process for producing a composition comprising at least one surface-modified silica, where a) a hydrophilic silica b) is first brought into contact with from 5 to 40 parts by weight per 100 parts by weight of hydrophilic silica of an α,ω-hydroxy-terminated oligodimethylsiloxane with an average molar mass of from 166 to 800 g/mol, where the contact takes place at temperatures of from −10° C. to 50° C., and c) then allowing the resultant reaction mixture to stand for at least 3 days at temperatures of from −10° C. to 50° C.
摘要:
Fumed silanized silica with the following physico-chemical data: Grindometer value less than 20 μm Tamped density 25 to 85 g/l is prepared by grinding fumed silica which has been silanized. It can be used in silicone rubber.
摘要:
Adhesive, comprising silanized, structurally modified, pyrogenically prepared silicas containing on their surface fixed vinyl groups or vinylsilyl groups, with hydrophobic groups, such as trimethylsilyl and/or dimethylsilyl and/or monomethylsilyl, additionally being fixed on the surface.
摘要:
A precipitated silica having a d50-value of from 150 to 2000 nm, a d90-value of from 500 to 7000 nm, a silanol group density of from 2.5 to 8 OH/nm2, and a modified tapped density of less than or equal to 70 g/l is useful for thickening and providing thixotropy in liquid systems and shows superior efficiency at thickening and creating thixotropy compared to existing grades of precipitated silica. The precipitated silica functions best as a thixotrope in non-polar or intermediate polar liquid systems such as unsaturated polyester (UPE) resin systems.
摘要:
Surface-modified silicas Surface-modified, highly structured, potassium oxide-doped silicas, characterized by BET surface area, m2/g: 25-400 average primary particle size, nm: 5-50 pH: 3-10 carbon content, % by weight: 0.1-10 potassium oxide content, % by weight: 0.000001-40 are prepared by subjecting a potassium oxide-doped silica to surface modification. It can be used as a filler in silicone rubber compositions.
摘要:
Thermoplastic elastomer, which comprises a fumed, hydrophilic or hydrophobic silica, which has been structurally modified and also a process for the improvement of the mechanical properties of thermoplastic elastomers. The thermoplastic elastomers are produced by preparing a masterbatch from the components (e.g. thermoplastic resin component and fumed silica) and compounding this with further thermoplastic elastomers.
摘要:
Surface-modified silicas Surface-modified, highly structured, potassium oxide-doped silicas, characterized by BET surface area, m2/g: 25-400 average primary particle size, nm: 5-50 pH: 3-10 carbon content, % by weight: 0.1-10 potassium oxide content, % by weight: 0.000001-40 are prepared by subjecting a potassium oxide-doped silica to surface modification. It can be used as a filler in silicone rubber compositions.