Purging compounds are necessary for plastic processing companies to maintain their production equipment. They dislodge the residues of previous production colors and resins that remain on cylinder walls and screws after the barrel is run empty. They permit these residues to be removed quickly from the machine that is then readily purged from the barrel by the next production color or resin. Companies can thus reduce the machine downtime that occurs when changing color or resin, and also improve the quality of molded parts by keeping their machinery, molding mechanisms and plastic molds free of contamination particles. Companies can change color quickly and easily, with minimal hassle and maximum efficiency. Purging compounds are used as a preventative maintenance tool: by purging machines of heat-sensitive resins at shutdown or in the initial stage of a mold changeover, plastic processors can prevent mold degradation and other costly issues before they occur. Many plastic processors use very expensive highly engineered plastics such as PPA, PPS, PEEK, PPO, PEI, PSU and PVDF for purging, which, by their nature process at temperatures up to 450°C, making them more prone to thermal degradation, in turn creating carbon build up leading to black specs. These polymers are at the high end of the costing structure and are usually processed in smaller quantities. Changing from black to lighter colours can take time, which also wastes this valuable polymer. By using Dyna-Purge E these problems can be eliminated. Dyna-Purge E meets a temperature range of 310°C to 380°C and using a relatively small amount will allow an efficient clean of the screw and barrel prior to a material or colour change. Used in conjunction with a shut down program waste can be reduced during the start up procedure. An improved grade Dyna-Purge® K, is a low-temperature, non-abrasive, non-chemical engineered thermoplastic purging compound. It is specially formulated to flow naturally through the machine and provide for a "dual power" cleaning technology. A non-melting but softening thermoplastic scrubs while a proprietary ingredient expands, removing contamination without leaving a residue. The enhanced formulation of new Dyna-Purge® K delivers a brighter, more powerful clean and is field proven to lower purging costs. It cleans faster and reduces scrap and reject rates, while only a small amount of the compound is required. It leads to up to 15% additional savings, and significantly increase productivity on injection molding and extrusion machines, purging a wide range of low temperature resins. Its is ideal for processing temperatures ranging from 290°F to 550°F (143°C to 287°C), it utilizes FDA-compliant ingredients. It is easy to use, with no mixing, soaking or machine adjustments required. Some other developments in purging compounds for high temperature engineering plastics include: Sun Plastech Inc.’s ASACLEAN PX added to its product line of ASACLEAN Purging Compound. ASACLEAN PX is a glass-filled grade offering a service temperature range of 518°F-788°F (270°C-420°C). The PX Grade is suitable to purge “super-engineering resins” such as PEEK, PPS, Ultem and LCP from thermoplastic injection molding machines and extruders. The PX Grade was specifically designed to provide excellent cleaning at higher processing temperatures while emitting low smoke and odor (which can be common occurrences when purging high-heat resins). Also available is unfilled Asaclean SX for hot-runner cleaning or machine shutdowns with use-temperature range is 570°F-735°F. SX Grade is designed to maintain thermal stability at high processing temperatures while facilitating material and color changes. It is uniquely suitable for purging new glass-filled high-temperature grade. Few pointers: • ASACLEAN SX should not be left idle in the machine at temperatures above 700°F (370°C) for more than 30 minutes as decomposition may occur. • The barrel should be kept full of ASCLEAN SX at all times to prevent oxygen from entering the barrel - excess oxygen will accelerate material decomposition/carbon formation and could potentially result in fire at the higher end of the recommended temperature range. • To minimize the potential of excessive smoke while purging, it is recommended that a bucket of water be kept near the machine. Purge piles should be placed in water immediately after coming back from the nozzle. If processing temperatures are at or near the maximum recommended temperature for the SX Grade, low to medium back pressure and screw speed are recommended. SuperNova™ Chemical Purging Compound is NOVACHEM's brand of ammonia-free high performance purging product offering several benefits including : Ease of use and operator friendly, Dust Free and Odor Free, FDA Certified and Environmentally Safe, Unsurpassed Purging Performance and Value SuperNova™ Regular Grade Purging Compound is used for purging all thermoplastic resins (including engineering grade resins) processed up to 550°F (288°C). It can be used with all types of injection molding, extrusion or blow molding process equipment. SuperNova™ HT Grade Purging Compound is used for purging engineering grade thermoplastic resins processed above 550°F (288°C) and for other high-viscosity resins such as high hardness rigid PVC's or extremely stiff polyolefins. It is also the grade of choice for use in extrusion blow molding systems that process heat sensitive resins like PVC. Chem-Trend has developed Lusin® Clean G410, a purging compound, formulated to operate at high temperatures, ranging from 300°C-415°C, and is compatible with PPO, PEEK, PPS, PSU and LCP materials. It is the first purging compound designed specifically to perform at these demanding high temperatures. It facilitates quick color change using a minimal amount of material, reducing color changeover time by up to 90% and reducing scrap from 50–90%. Lusin® Clean L101 F is a solvent-free mould cleaner that is non-flammable and can be sprayed directly into moulds with a temperature of up to 150°C, which substantially accelerates the mould cleaning process. It is NSF-registered as compliant with K1 and K3 requirements and thus suitable for use when manufacturing products that come into contact with food. In addition to removing plastic residues and their decomposition products from the mould, it is ideally suited to cleaning pre-mixers that have been contaminated by colour pigments. It does not contain either butane or propane and uses a VOC-neutral propellant obtained using environmentally-sound methods. Lusin® Alro OL 202 F is a silicon-free release agent specially designed for the thermoplastics industry. It is NSF-registered as compliant with H1 requirements and has a composition that conforms to the EU Plastics Directive 2002/72/EC. Owing to its listing, both European and US laws stipulate that it is suitable for use when manufacturing products that come into contact with food. The new mould release agent can withstand temperatures of up to 200°C. It is a highly effective and economical release agent that is suitable for almost all kinds of thermoplastics. Although the FDA does not regulate purging compounds used in thermoplastic processing, it may regulate their ingredients for certain applications. Sun Plastech Inc. contracted a third party laboratory to evaluate the ingredients of ASACLEAN Purging Compounds for FDA compliance. Their licensed toxicologist thoroughly reviewed the ingredients and found that all of the ingredients in the grades submitted for review are compliant with FDA regulations for indirect food contact applications (US FDA 21CFR). ASACLEAN Purging Compounds can be used with thermoplastic resins processed from 320°F-735°F. They are thermally stable, broadly compatible with various resins, and effective at facilitating color or resin changes while removing carbon and color deposits.