Polyolefin foams blowing agents

The use of CFCs as foam blowing agents has decreased 35% from 1986 levels. Polyurethanes, phenoHcs, extmded polystyrenes, and polyolefins are blown with CFCs, and in 1990 the building and appHance insulation markets represented about 88% of the 174,000 t of CFCs used in foams (see Foamed plastics). 

Expansion and crosslinking processes and blowing agents used in the preparation of low density polyolefin foams are examined. Properties of these foams are reviewed and related to structure, and major application areas are described. 148 refs. 

Polyolefin Foams. Antimony oxide/chlorowax combinations or other aliphatic chlorine sources are generally used to fire retard polyolefin foams. Because of the higher processing temperatures required (up to 280 C or 536°F), when using azo blowing agents, the antimony ox-ide/chlorine system is inadequate, and in these cases phosphorus-containing fire-retardant systems are preferred (38). 

Santechem 21-21. [Santech] Azoduxu-bonamide cone. blowing agent fix polyolefins, extruded and inj. molded structural foam. 

There are several processes for the production of moldable polyolefin beads. In the BASF process, LDPF foam strands are extruded out of a multi-hole die and granulated to beads by a die-face cutter. Inexpensive butane is used as the blowing agent and the foam beads are then cross-hnked by electron-beam. As the beads have atmospheric cell pressure, a special technique is required to develop the... 

OBSH is one of the best blowing agents of the sulfonyUiydrazide class. Its gas hberation characteristics (no stepwise change up to 140°C) makes it possible to obtain foams with small, uniform cells. It is nontoxic and does not impart color and smell to articles. OBSH is used for foaming PVC, polyolefins, polysulfides, microporous rubber, or foamed materials based on mixtures of polymers with rubbers. In the last case, OBSH acts additionally as a cross-linking agent. 

The most important thermoplastic foams are based on thermoplastic polystyrene and on the polyolefins PE, PP and PVC. The foaming process generally involves expansion resulting from use of chemical or physical blowing agents (Table 6). 

No matter what type of blowing agent is used, the foaming of polyolefins and polystyrenes using the expansion method comprises three fundamental process steps ... 

US 7045556 B2, Polyolefin foams made with isopentane-based blowing agents... 

Uses Blowing agent for foamed plastics, polyolefins, impact polystyrene, PP, ABS, etc. Trade Name Synonyms Blo-Foam RA [Rit-... 

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