Reaction injection molding mold curing

RIM—Reaction injection-molded urethane, cure t5 min, 80°C. Thermoplastic=BF Goodrich Estane 5701, fuse at 175 C. 1-Component—Dow Corning Urethane Bond , cure 3 days, room temperature. A—Age in boiling water, 2 h B —age in boiling water, 5 h C=cohesive bilure in polymer, >30 N/cm. 

There are no generalized models that include all these variables for thermosetting polymers. However, extensive work has been done on the viscosity of polyurethanes [9, 10] used in the reaction injection molding process. An empirical relation which models the viscosity of these mixing-activated polymers, given as a function of temperature and degree of cure, is written as... 

Reaction Injection Molding. RIM mixes polyol, polyamine, polyisocyanate, and strong catalyst, and injects the mixture rapidly into a mold, where it cures rapidly to form large parts very economically. It is used primarily for producing front ends and other large parts of autos. 

Reaction injection molding (RIM) is a fast, low-pressure, low-temperature, low-cost process for one-step conversion of reactive liquids into large finished solid plastic products. Liquid polyol and liquid diisocyanate are mixed by impingement, pumped instantly to fill a large mold cavity, and polymerize/ cure rapidly to form a thermoset polyurethane product. The cured polymer may be a stiffly flexible product such as automotive bumper covers, front ends, and trim or a rigid foamed product such as furniture and housings (cabinets) for computers, business machines, TY and radio. 

In painted SMC in particular (as weh as in RIM or RRIM - reinforced reaction injection molding - of polyurethane), mold release agents (zinc or calcium stearates) are used that exudate at the molding surface during curing/crosslinking and make for efficient demolding. 

Reaction Injection Molding (RIM). In reaction injection molding, liquid polyol and polyisocyanate are metered into a mixing head, which delivers the mixed liquid into a lightweight mold, where it polymerizes and cures rapidly to a finished polyurethane molded product. This is particularly useful in the auto industry, where it is used to mold large body parts very economically. 

The ROMP of DCPD by reaction injection molding (RIM) with ruthenium catalysts is possible with such heteroatom substituted ruthenium carbenes (7, 8) A molar ratio of DCPD/7 of 4700/1 was used and curing profiles measured as a function of the mold temperature, Figure 1. The polymerization and crosslinking of DCPD was very fast, completed within ca. 3 min. Conversions >95% and glass transition temperatures >140°C were obtained by RIM of DCPD with the new generation of ruthenium carbenes. 

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