Coagulated dispersion resins

The discovery of PTFE (1) in 1938 opened the commercial field of perfluoropolymers. Initial production of PTFE was directed toward the World War II effort, and commercial production was delayed by Du Pont until 1947. Commercial PTFE is manufactured by two different polymerization techniques that result in two different types of chemically identical polymer. Suspension polymerization produces a granular resin, and emulsion polymerization produces the coagulated dispersion that is often referred to as a fine powder or PTFE dispersion. 

Dispersion Resins. Polytetrafluoroethylene dispersions in aqueous medium contain 30—60 wt % polymer particles and some surfactant. The type of surfactant and the particle characteristics depend on the appHcation. These dispersions are appHed to various substrates by spraying, flow coating, dipping, coagulating, or electro depositing. 

Emulsion polymerization a sufficient amount of dispersing agent and mild agitation is employed. This produces small colloidal particles dispersed in the aqueous reaction medium. In this procedure, called aqueous dispersion polymerization, precipitation of the resin particles is avoided. The coagulated dispersion produced by emulsion polymerization is often called a fine-powder or PTFE dispersion. 

J. A. Jaffe, L. E. Robb and W. B. Happoldt jr. Teflon" tetrafluoroethylene resin dispersion-extrusion properties of lubricated resin from coagulated dispersion. Ind. and Eng. Chem. 44, 1805 — 1810 (1952). 

The Processing of PTFE Coagulated Dispersion Powder, Fluon PTFE Resins, Imperial Chemical Industries, Ltd.(1986)... 

Poly etrafluoroethylene is manufactured and sold in three forms granular, fine powder, and aqueous dispersion each requires a different fabrication technique. Granular resins are manufactured in a wide variety of grades to obtain a different balance between powder flows and end use properties (Pig. 1). Pine powders that are made by coagulating aqueous dispersions also are available in various grades. Differences in fine powder grades correspond to their usefulness in specific appHcations and to the ease of fabrication. Aqueous dispersions are sold in latex form and are available in different grades. A variety of formulation techniques are used to tailor these dispersions for specific appHcations. 

Beaded acrylamide resins (28) are generally produced by w/o inverse-suspension polymerization. This involves the dispersion of an aqueous solution of the monomer and an initiator (e.g., ammonium peroxodisulfates) with a droplet stabilizer such as carboxymethylcellulose or cellulose acetate butyrate in an immiscible liquid (the oil phase), such as 1,2-dichloroethane, toluene, or a liquid paraffin. A polymerization catalyst, usually tetramethylethylenediamine, may also be added to the monomer mixture. The polymerization of beaded acrylamide resin is carried out at relatively low temperatures (20-50°C), and the polymerization is complete within a relatively short period (1-5 hr). The polymerization of most acrylamides proceeds at a substantially faster rate than that of styrene in o/w suspension polymerization. The problem with droplet coagulation during the synthesis of beaded polyacrylamide by w/o suspension polymerization is usually less critical than that with a styrene-based resin. 

J m dia and dried by spray-drying or coagulation, are used as plastisol resins. Plastisols are dispersions of PVC in plasticizer. Heat allows fast diffusion of plasticizer into the PVC particle, followed by fusion (gelation), to produce a physically cross-linked elastomer, where the physical cross-links are PVC crystallites. 

Modicol . [Henkel/Functional Prods.] Ethoxylated ester coagulant wetting agent dispersant stabilizer, thickener, protective colloid for latex and resin emulsions. 

Co-coagulation is the method by which large quantities of fillers can be incorporated in dispersion polymerized polytetrafluoroethylene. The addition of fillers takes place prior to coagulation of the resin from its dispersion state. In the process of co-coagu-lation, the additives are added to the polytetrafluoroethylene dispersion and mixed. This dispersion is coagulated and the compound is recovered. The smaller the filler particles, the smaller the points of stress rise in the compound will be. Significantly larger quantities of filler can be compounded in PTFE by this technique. 

To obtain optimum adhesion, the film forming resin dispersion or solution should be added such that it does not gel or coagulate either the silica or the sodium silicate before adding them to the sand. For instance, the polymer resin dispersions can be mixed with the silica before adding to the sand because both are compatible and do not gel when mixed together. The mixtures can be added to sand and they will form an adhesive film on the surface of the sand grains. After the silica and the polymer resin dispersion have been mixed with the sand, the sodium silicate solution can be added to the sand and although it will thicken in contact with the silica and the polymer resin dispersion, it will do so in situ, that is. 

To obtain optimum adhesion, the film forming resin dispersion or solution should be added such that it does not gel or coagulate either the sUica or the sodium sUicate before adding them to the sand. For instance, the polymer resin dispersions can be mixed with the silica before adding to the sand because both are compatible and do... 

Uses Dispersant in boiler water treatment mineral scale control aid flocculant and coagulant aid in water and wastewater treatment, sugar processing migration inhibitor for use in continuous dyeing film-former in cosmetics hair spray resin in food-pkg. adhesives in food-contact paper/paperboard... 

Vinyl (dispersion type - Organosols ) Finish for office equipment Plasticiser Aromatic and aliphatic hydrocarbons Esentially a dispersion of PVC or a vinyl chloride copolymer in plasticiser/diluent. A high temperature is necessary to produce a continuous film. The solvent is required to reduce viscosity and assist dispersion. It must not swell the resin particles excessively or cause coagulation at room temp. 

Commercially, PTFE is produced from the monomer tetrafluoroethylene by two different polymerization techniques, namely, suspension and emulsion polymerization. These processes give two vastly different physical forms of chemically identical PTFE. While suspension polymerization produces granular PTFE resin, emulsion polymerization produces an aqueous PTFE dispersion and PTFE fine powders (after coagulating the dispersion). 

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