Thixotropic Additives

The hand lay-up or spray-up process, used universally for the production of laminar composites incorporating glass fiber reinforcement, is most efficient for the manufacture of large parts, such as boats, bathtubs, tanks, architectural shapes, and recreational accessories. Resins intended for spray-up processes are usually modified with thixotropic additives, such as fumed siHca (1%), to reduce the risk of drainage when appHed over large vertical mold surfaces. Molds are also made from ERP for short-mn products usually surfaced with a tooling gel coat to provide consistent surface quaHty and appearance. 

The alkoxy titanate compounds formed by reaction of one mole of tetraalkyl titanate with one mole of a dialkanolamine are excellent esterification catalysts for the manufacture of phthalate-based plasticizers (112). If a 1 1 molar mixture of alkanolamine and water is used ia place of the alkanolamine, oligomeric titanate complexes are formed, which have high catalyst activity and can be used as thixotropic additives to paints and other aqueous coating formulations (113). 

Several conditions are necessary for satisfactory surface coatings, e.g., nondrip applications. There is a balance between the ease of use and sagging of the paint during and after administration. Thixotropic additives, e.g., organo-montmorillonite clays are added. These form 3-dimensional networks, which are easily broken down by shear. 

Other Thixotropic Additives. Microcellular fillers such as glass and plastic are also used to provide nonsag properties to adhesives and sealants. However, their mode of operation is very much different from that of the rheological modifiers mentioned above. Microcellular fillers work because they drastically reduce the specific gravity of the product. Thus, because the adhesive or sealant is lighter, there is less stress on the adhesive or sealant due to the forces of gravity. 

There are numerous industrial products of colloidal silicas in various forms. The methods of industrial synthesis and main applications are briefly surveyed as follows. Ultra-fine particles of nanometer order such as aerosil (commercial name) are produced by the hydrolysis of tetrachlorosilane in air. A similar material can be obtained from oxidation of tetralkoxysilane in a gas phase. The former is used as a thixotropic additive of composite materials, heat insulator and etc. 

Crayvallac. [Cray Valley Prods. Ketto A/S] Thixotropic additives for paints. 

This rheologic behaviour is, however, in most cases rather obtained by appropriate binder design in combination with the pigments, the total solids content or the addition of special agents such as thixotropic additives than by solvent choice. 

Surfactants, nucleating agents and catalysts used in foaming processes Thixotropic additives for gel coat resins to control flow on the mould Tribological additives that reduce mechanical wear by friction. 

To prevent leakage of sealants from vertical surfaces, thixotropic additives are used, such as Si02, bentonites, and aqueous solutions of polyvinylic alcohol, which provide for an increase in viscosity from 500-600 to 3000 Pa-s. 

Thixotropic additives are mineral particles (MgO, Si02) that are characterized by a very high specific surface and an ability to develop interactions with the polymer by forming a sort of physical gel, they prevent flow and are reserved for materials processed by compression molding or calendering (PA, PVC, UP, etc.). 

Uses Neutralizer for agric. chems. grinding aid, strength improver, and set accelerator for concrete and cement metal forming lubricant thixotropic additive for paints/pigments demulsifier for petroleum/coal Properties Liq. sp.gr. 1.12 dens. 9.35 Ib/gal b.p, 372 C( 4.48 mm Hg) flash pt. (Seta) 198 C 87% TEA 13% higher Alkasil HNM 1223-15 [Rhodia Novecare]... 

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