Plastisol preparation

The effect of various plasticizers was studied for a number of plastisols prepared both from emulsion and suspension PVC 2>6,7,37 42 46 4% Judging from the published data 48), the most viscous plastisols are formed with mesamole, low-viscosity plastisols with dioctyladipate taken as a base, irrespectively of PVC type. Plastisol viscosity may be controlled by certain additives small smounts of certain solvents may lower plastisol viscosity by as much as an order of magnitude37,41>, the use of bentonites makes pastes more dense 40,48>. Thermoplastic polyethylene may also be used as a thickening agent6,42). 

Masenko LY (1981) Some features of PVC plastisols preparation and their coating onto polymer support. In Pererabotka i primenenie plastmass . Trudy NPO Plastik. NIITEKhIM, Moscow, p 37... 

To prevent the foam and blister formation during production and/or application the air release additive should be mixed with the plasticizer during plastisol preparation. 

There are two principal PVC resins for producing vinyl foams suspension resin and dispersion resin. The suspension resin is prepared by suspension polymerization with a relatively large particle size in the 30—250 p.m range and the dispersion resin is prepared by emulsion polymerization with a fine particle size in the 0.2—2 p.m range (245). The latter is used in the manufacture of vinyl plastisols which can be fused without the appHcation of pressure. In addition, plastisol blending resins, which are fine particle size suspension resins, can be used as a partial replacement for the dispersion resin in a plastisol system to reduce the resin costs. 

Market and actors While quite a lot of suppliers still exist on the PVC and phthalate markets, there are only three manufacturers of UBS plastisols in Germany, who are highly specialised in the manufacture of pasty preparations. 

Preparation of Plastisol. In all cases the plastisols were prepared on a Wink-worth-Z blade mixer and degassed before use at less than 0.1 mm. of Hg. The same order of mixing and similar mixing and degassing times were employed. A liquid cadmium-barium stabilizer was used. 

The carbon black plastic concentrates are often not prepared by the plastics processor. They may be purchased, from the pigment-black manufacturer in the form of chips, pellets, or powders. Black-plasticizer pastes (e.g., black/DOP pastes for tinting plastisols) and water- and solvent-based dispersions (e.g., for fiber manufacture) are also commercially available. 

Such a simplified approach nevertheless proved to be practically acceptable in view of the fact that fju may be taken as constant for the plastisol of the same formulation and preparation time. This probably follows from the relatively low initial viscosity as compared to that aquired by the material upon heating. 

Plastisol properties depend on a number of factors, the most important among which are the nature of the polymer (PVC), the identity of plasticizer and other additives, the composition of formulations, the conditions of preparation and storage, the load-velocity (first of all, stress and shear rate), and temperature conditions of processing. Depending on these parameters, the character of plastisol flow may vary widely. That is why, in spite of a number of papers devoted to the study of the rheological (viscous) properties of plastisols (e.g. 2,5 37,38)), these still can not be considered as well studied and widely accepted. 

The type of chosen polymer and additives most strongly influences the rheological and processing properties of plastisols. Plastisols are normally prepared from emulsion and suspension PVC which differ by their molecular masses (by the Fickentcher constant), dimensions and porosity of particles. Dimensions and shape of particles are important not only due to the well-known properties of dispersed systems (given by the formulas of Einstein, Mooney, Kronecker, etc.), but also due to the fact that these factors (in view of the small viscosity of plasticizer as a composite matrix ) influence strongly the sedimental stability of the system. The joint solution of the equations of sedimentation (precipitation) of particles by the action of gravity and of thermal motion according to Einstein and Smoluchowski leads 37,39) to the expression for the radius of the particles, r, which can not be precipitated in the dispersed system of an ideal plastisol. This expression has the form ... 

The formation of coagulum is observed in all types of emulsion polymers (i) synthetic rubber latexes such as butadiene-styrene, acrylonitrile-butadiene, and butadiene-styrene-vinyl pyridine copolymers as well as polybutadiene, polychloroprene, and polyisoprene (ii) coatings latexes such as styrene-butadiene, acrylate ester, vinyl acetate, vinyl chloride, and ethylene copolymers (iii) plastisol resins such as polyvinyl chloride (iv) specialty latexes such as polyethylene, polytetrafluoroethylene, and other fluorinated polymers (v) inverse latexes of polyacrylamide and other water-soluble polymers prepared by inverse emulsion polymerization. There are no major latex classes produced by emulsion polymerization that are completely free of coagulum formation during or after polymerization. 

Flame retarding plasticizer used in cellulose, polyester and polyurethane. Mainly used in the manufacture of electrical (wire and cable) and automotive plastic parts. May also be used for die preparation of vinyl sheets, fabric coating, plastisols and organosols, adhesives, vinyl packing materials, and conveyor belts. 

Thermoplastie prepared by free radical pol mier-ization of vinyl fluoride. It is extruded into thin (<100 pm) films as a plastisol (dispersion in a polar solvent). PVF is known for its weather resistance, release, adherability, and mechanieal strength. 

Details An oily liquid, used commonly as a plasticiser and plastisol in PVC (specifically for the preparation of PVC plastic films for biomedical and food packaging applications). 

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