Plastisol Casting

CAS 109-16-0 EINECS/ELINCS 203-652-6 Uses Adduct monomer for preparation of anaerobic adhesives and sealants, castings, plastisols, coatings, fibers, cast acrylic sheets, elec, photoresists, rubber prods., dental resins, overprint varnishes, and flexographic printing plates crosslinks and copolymerizes with other vinyl monomers imparting solv. resist., heat resist., and hardness Properties Pt-Co 100 max. clear liq. m.w. 286 vise. 10 mPa-s flash pt. 

Batch PVC plastisol or organosol casting Plastisol and organosol casting process involves melting the polymer or polymeric mixture by an action of the temperature and presence of either a plasticizer or solvent... 

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

During the past 10 years great strides have been made in the development and service application of highly loaded, synthetic rubber-base and interstitially-cast double-base composite-modified propellants. Largely for this reason and for economic and logistic reasons as well, the slurry-cast nitrocellulose plastisols have been relegated to a secondary role. 

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 upper limit depends quantitatively on the viscosity that can be processed through the casting fixtures in reasonable time. Too high a viscosity may also lead to problems under certain flow conditions as, for example, when propellant folds over on itself to form a void space which may remain as a defect in the cured grain. If the propellant grain is to be formed and cured by screw extrusion, however, somewhat higher viscosities can be handled. A viscosity of 1600 poise has been reported (9) for a PVC plastisol propellant processed this way. 

After mixing, the propellant is transferred into a casting pot, a container in which it may be held and from which it may be cast. The long pot life of mixed PVC plastisol propellant permits it to be held almost indefinitely to meet the convenience of the production schedule. The long pot life also makes possible the full characterization of a batch of mixed propellant, by extensive tests on batch samples, before the batch is committed to further processing. 

PVC plastisol propellant may be formed into the required size and shape to make the desired grains either by screw extrusion or by casting into molds. No exotherm or volume change is observed as a result of curing (16). Molds are normally bottom-filled, the propellant being forced into them from a pressurized casting pot. Heat to raise the propellant to curing temperature may be supplied by many means. The filled... 

Continuous screw extrusion is another way to form PVC plastisol propellant into the desired size and cross-sectional shape. Simultaneous curing of the propellant is also accomplished. This process has been described fully by Rossen and Rumbel (9) and is only summarized here. Mixed propellant is fed from a casting pot into the feed end of a continuous worm-screw extruder which is fitted at the discharge end of the screw with a device for constricting propellant flow. The action of the... 

Cowperthwaite, Coe, and Frissell (J) in their viscosity/temperature studies have defined the temperature at which the plastisol viscosity begins to increase as the gel temperature. These authors also studied the tensile strength of films cast on glass plates, fluxed at a series of temperatures between 300° and 425°F. They have defined the temperatures at which tensile strengths of 1000 and 1500 p.s.i. are attained as the fluxing temperatures. ... 

Casting the Plastisol. After the gel block had attained equilibrium temperature, a thin film of silicone grease was applied to the block, and vhen a strip of... 

Examination of Cast Film. The film can now be examined both before and after stripping from foil. A simple test was devised to determined the transition point from liquid to nonliquid state. A palette knife was drawn along the foil from the end where some of the plastisol was still liquid. Plastisol flowed easily in front of the knife until it came to a point where the plastisol was no longer spreadable. At this point, which was sharply defined, it was impossible to push the blade further. The temperature at which this occurs has been called the liquid/solid transition point (Figure 5). 

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. 

Rotational casting is usually used in making hollow articles such as vessels, dummies, dolls, buoys, floate, etc. The weighed amount of plastisol is given into a metallic sealed mould which then is rotated in three mutually perpendicular directions upon heating in a chamber furnace. Upon gelatination the mould is cooled, stopped, opened, and the article is taken out. 

Plastics film and sheet can be made in a number of different ways (including casting film from solvent or plastisols, pressing, and skiving from material in block form) but in commerce the most important processes for making these intermediates from thermoplastics are calendering and extrusion. 

The 121 sample films were formulated into a replicate series. Those utilizing emulsion polymerized PVC were cast from plastisol onto glass plates and fused in a circulating hot air oven. Those incorporating suspension polymerized PVC were fluxed via a Banbury and two-roll compounding mill and finished on an inverted L 8-inch X 16-inch four-roll calender. Plastisol films were of nominal 8-mil thickness calendered film was 4 mils. 

Rotational Casting. Like rotomolding, the plastisol is poured into a cold mold, which is rotated and heated to gel the plastisol onto the walls of the mold. It is then heated to fuse, cooled to solidify, opened, and the product removed. Typical products are volley balls, basketballs, dolls, and auto parts. 

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