Plastisol techniques

An important development was the use of plasticizers which crosslink upon application of heat and thus produce a more rigid end product. This extends the range of products obtainable by plastisol techniques into rigids. Ry varying the amount of crosslinking plasticizer incorporated, various levels of flexibility are obtained. 

Thermoplastic resins, such as vinyl chlorides, vinyl acetates and polyamides are employed, particularly in the water industry, on buried pipes and fittings. To provide both internal and external coating, application may be by one of these principle techniques dipping in a plastisol, fluidised beds or electrostatic spray. 

Thermoplastics which are used for corrosion protection can be applied in coatings as thin as 0.025 mm by solution techniques and in excess of 5 mm by extrusion or plastisol dipping. They are used where environmental resistance, chemical resistance, abrasion resistance, sound deadening or cushioning are required. They are used in those market areas that necessitate metallic mechanical strength plus thermoplastic corrosion resistance. 

The coating technique starts by applying a solvent-based adhesive on to a previously pretreated metal substrate. The item is then preheated to 200-250°C, the exact time and temperature depending on the metal thickness. It is then dipped in the plastisol which partly gels owing to the... 

A procedure for proplnts is presented by J.W. French (Ref 27), who used both OM and EM (electron microscope) to study plastisol NC curing. He found that the cure time of plastisol NC is a logarithmic function of temp, and direct functions of chemical compn and total available surface area, as well as of particle size distribution. It should be noted that extensive use of statistics is required as a time-saving means of interpreting particle size distribution data. The current state-of-the-art utilizes computer techniques to perform this function, and in addition, to obtain crystal morphology data (Ref 62)... 

Additionally, plastisol ( paste ) type PVC compounds are in the form of a thick paste that can be applied by techniques such as coating, dipping, or rotational moulding. 

Figure 3 Cushionflor techniques for obtaining printed/relief PVC plastisol floor covering. Adapted with permission from D.H. Morton-Jones, Polymer Processing, Chapman Hall, London, 1989.

Plastisols allowing the use of particular liquid-state processing techniques casting, roto-moulding, dipping, coating... 

It is in the technique of solidifying the mass that plastisol propellants differ so markedly from composite propellants. In composite propellants, the nonvolatile liquid is comprised of monomers or low molecular weight prepolymers. Solidification is accomplished by completion of the polymerization reactions. Much attention must be given to the degree of completion of these reactions during manufacture so as to minimize changes in physical properties as a consequence of continued slow polymerization, or so-called post-cure, following manufacture. 

It is surprising therefore that after such a lapse of time, we should consider it interesting to discuss laboratory techniques for the study of the effect of temperature on the properties of PVC plastisols. 

The primary processing techniques are by means of extrusion, calendering and molding. Special techniques involve organosols and plastisols. 

Plastisols allow the use of inexpensive manufacturing techniques, such as slush and rotational molding, casting, dipping, etc. They are employed for tile manufacture of a large variety of parts, e.g., toys, floor mats, handles and many others. 

Design Technique for the Process of Mould Filling and Gelatination of Plastisols. 

Design Technique for Mould Filling in Considering Plastisol Gelatination 123... 

The pastes used are plastisols—finely divided polymer dispersed in plasticizer. They are mobile mixtures which may range in viscosity from liquids that can be poured readily to thick pastes—the viscosity depending essentially on the type of resin and the amount and type of plasticizer involved. Such mixtures can be applied to substrates by coating or by techniques akin to printing after application they are converted into homogeneous flexible vinyls by heating to temperatures in the range 175 to 200 °C, when the dispersed particles of resin dissolve in the plasticizer and are fused into a continuous structure.1... 

The technique is very versatile and adaptable. Plastisols may be applied overall or—by means of engraved screens—can be printed in selected areas, in weights that can be varied between 30 g m-2 and more than 500 g m-2. Suitable substrates include paper, other non-woven materials, glass-fibre webs, and textiles. Water-based inks can be employed as coatings or in printed designs. For relief effects, expandable aqueous polyacrylate dispersions offer an alternative to expandable plastisol inks. They are dried and then expanded at 120°C, a temperature much lower than is required for vinyls with a multi-station machine, a wide variety of products can be made. 

Plastisol is a specialized technique for making flexible vinyl products. It is also sometimes called paste or dispersion technology. Basically, powdered PVC is stirred into liquid plasticizer at room temperature to form a viscous liquid or spreadable paste. This can be poured or spread into the shape of the final product, heated to fuse, and cooled to gel into the final solid product. Simple pouring or gentle spreading require no heavy equipment, and do not damage delicate substrates such as... 

A study of the effects of several different plasticisers on the density, elasticity and degree of expansion of foams, produced from different PVC plastisols, has been reported (120). A three-dimensional and high resolution quantitative image technique has been proposed for the investigation of the internal microstructure of foams. This provides a tool to study the relationships between foam structure and physical properties (18). 

PVC plastisol compounds can be manipulated into shapes, or applied to fabrics in the ungelled state by either simple flow techniques or by very low pressure processes. The main techniques are spreading, dipping, spraying and rotational and slush moulding. 

The behaviour of PVC and PVC plastisols were studied during their thermal treatment using an in situ FTIR technique. Differences in the behaviour of certain bands corresponding to the plasticiser and the resin as a consequence of the interactions among them are discussed. 28 refs. 

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