Plastisols processing

In the plastisol propellant process, it is essential that the resin particles not solvate too rapidly at processing temperature since a rapid increase in viscosity of the propellant mix interferes with the mixing and casting operation. There must be adequate pot life of the mixed propellant. The resin-plasticizer system itself is the dominating influence on pot life, and for this reason certain combinations cannot be used in the plastisol process. 

The new method of plastisol processing called, low-pressure moulding has been developed during recent years. The procedure involves the filling of closed moulds... 

Masenko LY (1983) Study on PVC plastisol processing. Candidate s Thesis, Moscow, MITKhT... 

The plasticized product can be produced by mixing the polymer and plasticizers at elevated temperatures, also by dry blending in which the plasticizer is absorbed into the resin and then heated. Solution blending is sometimes used, as well as the plastisol process, in which fine polyvinylchloride powder is dispersed in the plasticizer which is relatively stable until it is heated. 

In a plastisol process the gelation of PVC paste, which is a suspension of PVC particles in a plasticizer such as tritolyl phosphate, involves diffusion of the plastidzer into the polymer mass, resulting in a rise of the paste viscosity. Diffusion processes are involved in the production of cellulose acetate film by casting from solution, as casting requires removal of the solvent. Diffusion also plays a part in plastic molding. For example, lubricants in plastics compositions are required to diffuse out of the compound during processing to provide lubrication at the interface of the compound and the mold. Incompatibility with the base polymer is therefore an important criterion in the choice of lubricants in such cases. 

Uses Lubricant in calendering rigid film stabilizer for plastisol processing. artificial leather, wallpaper, conveyor belts, toys, automotive applies., food-contact applies. 

Figure 10.25. Hydrocysts and bad distributions in a PVC plastisol processed by rotational molding.

Polyvinyl Chloride. In plastisol processing, PVC is dispersed in hquid plasticizer then fused to a sol and cooled to a gel to produce rubbery products. When the processor wants to decrease the plastisol viscosity without excessive softening of the final product, he uses a polymerizable plasticizer such as a glycol diacrylate (Fig. 3.71) plus a little peroxide. The plasticizer gives a more fluid plastisol, and then, during hot fusion, the peroxide crosslinks the plasticizer to prevent excessive plasticization of the finished product. 

Table 8.1 indicates the annual consumption of emulsion-grade PVC used in plastisol processes. The major use of emulsion-grade PVC has been in sheet... 

Some of the larger-volume plastisol processes are described below ... 

For example, Geon Vinyl Plastisol Processing Guide G-74 (1983). 

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