Vinyl latices

The binder, therefore, must have the following properties good adhesion to fibre and pigment in the dry state, and in water and solvent a soft, non-tacky handle elasticity lightfastness, clarity and no colour compatibility with, and stability towards, other ingredients in the mix. Some styrene butadiene copolymer rubbers and vinyl latices are used successfully but the most suited are the acrylics. The polymers are usually either self-cross-linking (with heat) or incorporate a cross-linkable resin such as melamine-formaldehyde. 

So far we have discovered very few polymerization techniques for making macromolecules with narrow molar mass distributions and for preparing di-and triblock copolymers. These types of polymers are usually made by anionic or cationic techniques, which require special equipment, ultrapure reagents, and low temperatures. In contrast, most of the commodity polymers in the world such as LDPE, poly(methyl methacrylate), polystyrene, poly(vinyl chloride), vinyl latexes, and so on are prepared by free radical chain polymerization. Free radical polymerizations are relatively safe and easy to perform, even on very large scales, tolerate a wide variety of solvents, including water, and are suitable for a large number of monomers. However, most free radical polymerizations are unsuitable for preparing block copolymers or polymers with narrow molar mass distributions. 

Chemical-resistant gloves, footwear, and aprons that are labeled as disposable are designed to be worn only once and then thrown away. These items often are made of thin vinyl, latex, or polyethylene. These inexpensive dis-... 

Emulsion polymerization is considered the generally accepted technique to produce dispersion (plastisol) resins and vinyl latexes today. The monomers are made dispersible by emulsifiers in a continuous water phase. The initiators or catalysts are water soluble while the emulsifying agents stabilize the emulsion formed when the system is agitated. Gellner (2 ) cites the following advantages of emulsion polymerization over other methods ... 

Dispersion or plastisol resins are made exclusively by emulsion polymerization techniques. A vinyl latex is a colloidal suspension (emulsion) of the homo-copolymer particle in water. (The 0.2 )jm average particle size is small enough to be in Brownian movement.) Soaps are generally used to form a protective colloid around the particle, and they are surrounded by a negative electrical charge. In some cases air-dry film-forming systems are possible. 

The basic principles regarding the selection of a plasticizer remain the same with a latex system as with the other polymer systems if only end properties of the final film are to be considered. The vinyl latexes require very little reorientation of thought with respect to compounding philosophy. As the copolymers are introduced, each system will have to be considered on its own merits based on the chemistry of the polymers under study. 

High-solid vinyl latexes can "skin over" in a dip tank if agitation is not provided. (Note many metal pretreatments make metal surfaces hydrophobic, i.e., it will not be wet out readily by a water-based system). 

Large irregular-shaped objects that are impossible to coat by dipping can be protected by spraying. All the liquid vinyls can be handled in this manner. Low-viscosity systems such as the solution vinyls and latexes can be handled easily on conventional suction feed equipment. Because of the acidic nature of vinyl latexes, the materials of construction of the spray equipment will have to receive special consideration. 

The vinyl latex systems are similar to the solvent vinyl systems with respect to coating characteristics that is, they both have low coating viscosity. Removal of at least 50% of the coating weight as water requires ovens with minimum available temperatures of 212 °F. Since organic solvents are not present, fire hazards are diminished. The high emulsifier levels in these systems will limit their applications where water contact or sensitivity are important... 

Various vinyl latexes, previously polymerized, were mixed with natural rubber latex, both still in aqueous dispersion, and then coagulated. Thus, core-shell latex and latex blend materials were known very early. 

Features May be used with vinyl latexes high b.p. 

Uses Emulsifier defoamer for dehydrating, evaporating, abrasive slurries, metalworking, adhesives, antifreeze, hotaq. systems, water-based inks and paints, vinyl latex binders and emulsions, petrol., textiles, paper, cutting oils, fermentation processing, commercial cleaning compds., insecticides/pesticides... 

Uses Emulsifier defoamer for adhesive, water-based paints soap mfg., antifreeze, hot aq. systems, insecticides, textile, paper, petrol., vinyl latex binders and emulsions, boiler water defoaming, leather finishing, metalworking, and waste treatment... 

Dynasylan 1172 Dynasylan 2201 Maleic resle, Photomer 4771 adhesion promoter, vinyl latex Sllquest A-1106 adhesion promoter, vinyl resins... 

FoamStar A410 defoamer, varnishes Forbest 1000B Metolat 288 defoamer, vinyl latex emulsions Mazu DF 210SX defoamer, vinyl resin paints Additol VXW 4951 defoamer, vinyl resins BYK -065 BYK -141 defoamer, vinyl-acrylic emulsions Drewplus L-493 defoamer, vinyl-actylic latex Antibubble DF-134 Antibubble DF-135 Colloid 985... 

Acrylamido-2-methylpropanesulfonic acid protective colloid, acrylic/vinyl latex Ethyl hydroxyethyl cellulose protective colloid, adhesives Hydroxypropylcellulose Sodium polyacrylate protective colloid, aq. paints Methylcellulose protective colloid, baking Albumen... 

This technology produces vegetable oil based emulsions which will dry to touch rapidly and allow water clean-up equivalent to acrylic and vinyl latex coatings. 

Commercial latexes are supplied both as thermoplastic and thermosetting types. Thermoplastic acrylic (and vinyl) latexes are very commonly used as binders for architectural paints and some specialty coatings. Such coatings are required to dry under ambient conditions without any chemical cross-linking and hence are designed to precise T and minimum film formation temperature. 

Figure 2.4 Gloves. Clockwise from the top neoprene gauntlet, PVC, butyl rubber, vinyl, latex, unsupported nitrile NBR, nylon-polyolefin fiber (for cryogenic work), nitrile, natural rubber, texturized silica (Zetex).

The above biocides are generally also available as emulsions for use with vinyl latex. These may be supplemented for protection before use with a water-soluble biocide such as dimethoxane (DXN, Dow Chemical). 

In plastisol and organosol formulation, as is also the case with vinyl latex and solutions, the technologist is concerned with processing a multiphase system prior to gelation and fusion, but that is where processing usually ends. This is distinct from formulation of dry compounds, where processing usually continues after the composition has fused that is, that shaping into articles is accomplished after, rather than prior to, fusion. This both limits and provides opportunity for the plastisol formulator. 

Instead of a hydrocarbon diluent, a ketone or ester may be used instead, in which case it is usually referred to as a dispersant rather than a diluent, reflecting its vinyl compatibility. Typical additives in this class are diisobutyl ketone and hexyl acetate. They have a greater effect on viscosity than hydrocarbons, but require greater investment to achieve solvent recovery. Blends of hydrocarbons with ketones or esters provide cost savings, but not only are they difficult to recover efficiently but it is also difficult to maintain constant composition during recirculation. If suitable solvent recovery systems are not available, the fabricator would be well advised to consider other approaches, such as compoimding vinyl latex. 

Uses Antifoam for adhesives, calcium chloride brines, hot aq. systems, insecticides, ink mfg. (water), paint m. (water), pulp dewatering, papermaking, cardboard mtg., textile dyeing and scouring, detergent, antifreeze wastewater treatment, latex binders, vinyl latex emulsions, boiler water defoamer, cooling low-... 

Poly(vinyl acetate) is used in latex water paints because of its weathering, quick-drying, recoat-ability, and self-priming properties. It is also used in hot-melt and solution adhesives. 

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