Silicone-elastomer catalyst

Uses Heat stabilizer for vinyl resins, lacquers, elastomers lubricant for flexible vinyls catalyst for PU foam and silicone elastomers catalyst forfood-contact PU resins and PU resins in food-pkg. adhesives plasticizer... 

DKR of a-hydroxy ketones with Shvo s catalyst (racemization) and lipase TL (esterification) Lipase encapsulated by silicone elastomer spheres... 

RESINS (Synthetic). A manufactured high polymer resulting from a chemical reaction between two (or more) substances, usually with heat or a catalyst. This definition includes synthetic rubbers and silicones (elastomers), but excludes modified, water soluble polymers (often called resins). Distinction should be made between a synthetic resin and a plastic the formei is the polymer itself, whereas the latter is the polymer plus such additives as niters, colorant, plasticizers etc. See also Elastomers and Plasticizers. 

Sealants (sealing materials) and compounds (filling materials) are thickflowing pastes which solidify in the cold. They are prepared by mixing low-molecular silicone elastomers with mineral ingredients. Sealants and compounds are supplemented with special catalysts which help them to solidify in the cold. Before using sealants or compounds, the surface of the product is sometimes covered with a sub-layer to improve adhesion. 

Tin organohalogenides can be used as catalysts to produce ethers of phosphoric acid and to polymerise lactons forming colourless polyesters. Various halogen derivatives of dibutyltin have been put forward as catalysts for the solidification of silicone elastomers, as agents preventing the cracking of polystyrene, as inhibitors of metal corrosion in silicone polymers. 

Ethyl p-aminobenzoate was used as the test compound for determining release characteristics. It was suspended in silicone elastomer base (Dow Corning Silastic, type 382). After the benzoate was thoroughly dispersed in the elastomer, the catalyst was added and the voids in the device were immediately filled. When cured, excess rubber was trimmed off so that the bottoms of the cells were flush with the lower surface of the device. 

Dibutyltin and dioctyltin diacetate, dilaurate, and di-(2-ethylhexanoate) are used as catalysts for the curing of room-temperature-vulcanized (RTV) silicone elastomers to produce flexible silicone rubbers used as sealing compounds, insulators, and in a wide variety of other applications. Dioiganotin carboxylates also catalyze the curing of thermosetting silicone resins, which are widely used in paper-release coatings. 

Tin(II) salts (e.g. acetate, oxalate, oleate, stearate, and 2-ethylhexanoate) are catalysts for the curing of silicone elastomers and polyurethane foam. 

Textile chemical auxiliary suppliers will provide suggested recipes in their product information. These recipes will contain recommendations for the appropriate catalyst and other additives that improve the performance characteristics of the easy-care and dnrable press finishes, such as softeners to improve the fabric handle and prodncts to improve tear strength (for example polyvinyl acetate, amino-modified or epoxy-functional silicones). Less decrease in degree of polymerisation (DP) rating and abrasion resistance is provided by adding water-based poly-nrethane emulsions of self crosslinking silicone elastomers. 

Silicone elastomer softener which, when used with HYDROCAT SE-47 (catalyst), imparts a soft, full-bodied, resilient finish. Enhances stretch recovery. Durable to both laundering and dry cleaning. 

This controlled-release subdermal implant is fabricated by dispersing micronized estradiol crystals in a viscous mixture of silicone elastomer and catalyst and then coating the estradiol-polymer dispersion around a rigid (drug-free) silicone rod by an extrusion technique to form a cylinder-shaped implant (Fig. 11). This implant is designed for subcutaneous implantation in the steer s ear flap for a duration of 200 or 400 days, during which a controlled quantity of estradiol is released daily for growth promotion. 

This subdermal controlled-release implant is fabricated by dispersing the drug reservoir, which is a suspension of norgestomet in an aqueous solution of PEG 400, in a viscous mixture of silicone elastomers by a high-energy dispersion technique. After adding catalyst. 

Use Stabilizer for vinyl resins, lacquers, elastomers catalyst for urethane and silicones. 

Many of the silicone elastomers that are used in biomedical applications are produced by Dow Chemical Corp., under the trade name SILASTIC . For example, a typical medical-grade silicone (like SILASTIC MDX4-4210 Medical grade elastomer) contains, after curing, cross-linked drmethylsiloxane polymer and silica for reinforcement. Silcones are also reinforced with PET (Dacron) fiber meshes for certain biomedical applications. For implantable medical devices, it is important to realize that the cured polymer contains residual catalysts and silicone cross-linkers, which are necessary for the polymerization. 

The importance of organotins as environmental endocrine disrupters and their potential to adversely affect human health, has prompted the European Commission to identify tributyltin (TBT) as a priority hazardous substance. Organotin compounds are widely employed as stabilizers of polyvinyl chloride (PVC) polymers, and as industrial catalysts for polyurethane and silicone elastomers. Hence, they are present in water pipes, food packing materials, polyurethane foams and many other consumer products. The prominent toxicological feature of the organotins is their immunotoxicity, and the effect produced by di- and trialkyltins as well as triphenyltins. 

Properties Lt. yel. liq. sol. in benzene, toluene, petroleum ether, aromatic soivs. insol. in water, methanol m.w. 405.11 dens. 1.25 flash pt. > 230 F ref. index 1.4930 Toxicology TLV 0.1 mg(Sn)/m of air toxic irritant Uses Polymerization catalyst for mfg. of PU foam, coatings, adhesives, sealants, elastomers lubricant addition agent stabilizer for transfonner oils curing agent for RTV silicone rubber catalyst for PU resins in food-pkg. adhesives Regulatory FDA 21CFR 175.105... 

Uses Polymerization catalyst for mfg. of PU foam, coatings, adhesives, sealants, elastomers lubricant addition agent stabilizer for transformer oils curing agent for R7V silicone rubber catalyst for PU resins in food-pkg. adhesives... 

Tetrasodium EDTA Trisodium EDTA catalyst, sealants Triethylene diamine catalyst, shoe soles Diazabicycloundecene catalyst, SHOP process Nickel chloride hexahydrate catalyst, silicone elastomers Dibutyltin dilaurate catalyst, silicone rubber curing Bis (2,4-dichlorobenzoyl) peroxide catalyst, silicone rubber 2-component Chloroplatinic acid catalyst, slabstock N,N,N -Trimethyl-N -hydroxyethylbisaminoethylether catalyst, SO2 oxidation Cesium sulfate catalyst, solder fluxes Isooctyl acid phosphate catalyst, soldering fluxes Ethyl acid phosphate 2-Ethylhexyl phosphate Stearyl acid phosphate catalyst, solid fuels Ferric acetylacetonate catalyst, solid rocket fuels Copper nitrate (ic) catalyst, solvent extractants Ethyl acid phosphate 2-Ethylhexyl phosphate Stearyl acid phosphate catalyst, solvent hydrogenation beer-making hops... 

The peroxide serves as a producer of radicals and is not being built into the polymer. The result of this vulcanisation is a chemically inert product. The use of a catalyst is not necessary and with a right choice of the peroxide, combined with an after-treatment of the material (extraction of the peroxide) a rubber that releases only very small amounts of substances is produced. This method is being used for the production of silicon-elastomer and of ethylene-propylene rubber. 

---