Plastisols

Plastisols are used in automotive assembly for lower performance applications, e.g. the bonding of panel reinforcements. An advantage here is that they are capable of bonding oily surfaces some absorb the oil film during cure, reducing the required surface preparation. Also, the adhesive may be formulated such that it cures during the paint-stoving process. 

There are many formulations of inorganic adhesives. Often they are one- or two-part paste or cement-like compounds for specific applications. The general areas of use are  

The composition of the ceramic phase largely dictates the temperature and chemical resistance of the adhesive. 

These are based on dispersions of plasticised PVC and cure structural applications and the classes of adhesives which on heating. The curing mechanism involves the absorption are most frequently used. 

---

Plastics carboys Plastics compounding Plastics, engineering Plastic sheet Plastics processing Plastics testing Plastic tapes Plastic working Plastiform Plastisols... 

PVC copolymers PVC foams P V C formulation PVC plasticizers PVC plastisols PVC resins... 

Urethane grouts Urethane industry Urethane linkages Urethane plastisol Urethane polyesters Urethane polymers... 

A type of physical stabili2ation process, unique for poly(vinyl chloride) resias, is the fusion of a dispersion of plastisol resia ia a plastici2er. The viscosity of a resia—plastici2er dispersioa shows a sharp iacrease at the fusioa temperature. Ia such a system expansioa can take place at a temperature corresponding to the low viscosity the temperature can then be raised to iacrease viscosity and stabili2e the expanded state. 

Another type of extmsion process iavolves the pressuri2ation of a fluid plastisol at low temperatures with an iaert gas. This mixture is subsequently extmded onto a belt or iato molds, where it expands (109,110). The expanded dispersion is then heated to fuse it iato a dimensionally stable form. 

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. 

The elastomer process is very similar to the Dennis process. It involves a number of steps in which a gas, formerly carbon dioxide and now fluorocarbon, is mixed with a plastisol under pressure. When released to atmospheric pressure, the gas expands the vinyl compounds into a low density, open-ceUed foam which is then fused with heat. 

The Vanderbilt process involves the mechanical frothing of air into a plastisol containing proprietary surfactants by means of an Oakes foamer or a Hobart-type batch whip. The resulting stable froth is spread or molded in its final form, then gelled and fused under controlled heat. The fused product is open-ceUed with fine cell size and density as low as 160 kg/m (10 lbs/fT). 

The Kleber-Colombes rigid PVC foam (253,254) is produced by compression mol ding vinyl plastisol to react and gel the compound, followed by steam expansion. The process involves mixing, mol ding, and expansion. The formulation consists of PVC, isocyanate, vinyl monomers such as styrene, anhydrides such as maleic anhydride, polymerization initiators, FC-11, and nucleators. The ingredients are mixed in a Wemer-Pfleiderer or a Baker Perkins... 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

AppHcatioas of dibasic lead phthalate, coated grade, iaclude 90 and 105°C rated PVC electrical iasulation, plastisols, profile extmsions, calendered sheet, and molded products. The recommended range of usage ia viayl electrical iasulatioa is 5—7 parts pet huadred resia, depending oa the particular iasulatioa classiftcatioa to be met. Ia geaeral-purpose extmded and molded PVC stocks, approximately 3—6 phr of coated dibasic lead phthalate is suggested. 

Plastics. Lecithin (0.5—1.5%) is used for pigment dispersion and as a shp or release agent. It also may be sprayed on molds. It has surfactant effects in organosols and plastisols (see Surfactants). 

Thermoplastic pigments for use in paint, screen ink, plastisol, gravure ink, paper coatings, and many other appHcations. d. . ... 

For vinyl plastisol, organosol products and calendering, Day-Glo Color Corp. offers T, D, VC, and AX-Series pigments, Lawter Chemical offers the B-3500 and G-3000 Series, and Radiant Color offers P-1600 and R-203-G Series. In addition, Day-Glo offers VC Series for vinyl calendering where nonformaldehyde products are needed. 

In knife-over-roll or blade coating, the coating material is placed on the fabric surface behind a knife, or doctor blade, and metered according to the gap set between the blade and the fabric surface. This method is used to apply thick coatings of highly viscous materials such as pastes, plastisols, or foams. 

Plastisols may also be semi-geUed for storage, ie, enough heat is imparted to convert the plastisol into a soHd but without the full development of tensile properties brought about by full fusion. 

Plastisol Viscosity and Viscosity Stability. After the primary contribution of the resin type in terms of its particle size and particle size distribution, for a given PVC resin, plastisol viscosity has a secondary dependence on plasticizer viscosity. The lower molecular weight and more linear esters have the lowest viscosity and hence show the lowest plastisol viscosity, ie, plastisol viscosity for a common set of other formulation ingredients... 

Plastisols are often mixed and then stored rather than processed immediately (Fig. 5). It is of great importance in this case for the plasticizer to show htde or no paste thickening action at the storage temperature, and clearly it is not advisable to use a plasticizer of too great an activity, since grain sweUing, leading to plastisol viscosity increase, can occur at low temperatures for some active plasticizer systems. 

Fig. 5. Viscosity aging of plastisols at 23°C where A is BBP/DIPB B, DOP C, FllO and D, 911P.

Plasticizers for acryhcs include all common phthalates and adipates. There has been interest in the development of acryUc plastisols similar to those encountered with PVC. Clearly the same aspects of both plastisol viscosity and viscosity stabiUty are important. Patents appear in the Hterature (32) indicating that the number of available plasticizers that show both good compatibiHty with acryHc resins and satisfactory long-term plastisol stabiHty may be fewer than those showing equivalent properties with emulsion PVC resins. 

---