Thermoplastic powders

These methods process powdered thermoplastics and may involve high-voltage currents. Consequently, it is necessary to obey all health, safety and environmental precautions and regulations. 

The use of the vinyl polymer in fluid form offers distinct advantages to the manufacturer of vinyl products. The most important obvious advantage is the relatively lower cost of liquid processing equipment and accessories as compared to those required for processing of solid or powder thermoplastics. For example, a spread coating line, for example, knife or roll coater, even with appropriate unwind and takeup accessories, is less expensive than a banbury-mixer-mill calender configuration. 

U.S. Pat. Nos. 6,344,504 [102] and 6,498,205 [103] (both by Crane Plastics Company, TimberTech) disclose a thermoplastic-based composite, comprising at least 16% by weight of a powdered thermoplastic material, at least 50% by weight of cellulosic material, and a lubricant, a phenolic resin, and a compound containing one or more isocyanate groups, each of at least 1% by weight. A powdered thermoplastic material comprises polyethylene, LDPE, polypropylene, ethyl-vinyl acetate (EVA), and polyethylene copolymers. 

U.S. Pat. No. 6,344,504 (February 5, 2002). B.E. Zehner and T.C. Laver. An extruded wood simulative material is described which includes a high degree of cellulosic material content and begins with powdered thermoplastic material. 

DTM Corp., Austin. TX. USA Sinterstation 2000 Powderized thermoplastics (PA PC), wax local melting of the powderized plastic by laser energy... 

US 20120172534 Al, Powdered thermoplastic polyolefin elastomer exrmposition fra- slush molding processes... 

Triboelectric characteristics allowing charging of the carbonaceous powder. Thermoplastic nature important to fusion process. See Ref. 96 for a leading reference... 

Nonblocking powdered thermoplastic rubber can be made through the use of a special solvent system. In this method, rubber crumb is dispersed in a high solubility parameter solvent which will barely dissolve the endblock domains and which will not dissolve the rubber phase at all. One such single solvent is acetone. Particle size of the crumb is controlled by the amount of shear used in dispersion. Addition of water totally precipitates the small particles. This powder may then be separated from the liquid and dried. The particles do not tend to agglomerate because the hard endblock phase preferentially coats the outside of each particle. 

STUDY ON THE WASTE TIRE POWDER/ THERMOPLASTIC BLENDS... 

Although it would be desirable to recycle laminate scrap, this has been difficult because of its thermoset nature. However, a 1993 patent (18) suggested a means whereby scrap consisting of cellulose, thermoset resins, and partially reacted resins can be ground to a powder which is used as a filler in a thermoplastic resin. The filled thermoplastic resin is then used for mol ding of various articles. 

Recycling. Thermosets are inherently more difficult to recycle than thermoplastics and thermosetting phenoHcs are no exception. However, research in this area has been reported, and molded parts have been pulverized and incorporated at 10—15% in new mol ding powders. Both German and Japanese groups had instituted this type of practice in 1992 (71,72) (see Recycling). 

The diversity of release products and the wide range of release problems make classification difficult. One approach is by product form, with subdivisions such as emulsions, films, powders, reactive or iaert sprays, reactive coatings, and so on. Another approach is by appHcation, eg, metal casting, mbber processiag, thermoplastic iajection mol ding, and food preparation and packagiag. 

The volume of thermosetting powders sold exceeds that of thermoplastics by a wide margin. Thermoplastic resins are almost synonymous with fluidized-bed appHed thick-film functional coatings whereas thermosetting powders are used almost exclusively in electrostatic spray processes and appHed as thin-film decorative coatings. 

Table 1. Physical and Coating Properties of Thermoplastic Powders ...

Thermoplastic polyesters achieved some commercial success during the mid-1980s however, these were eventually replaced by nylon coating powders in functional coatings and thermosetting polyester powders in decorative appHcations because of lack of any unique characteristics or price advantages (see Polyesters, thermoplastic). 

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