Internal mold release agent, requirements

Internal mold release technology is well developed for nylon RIM systems while it is being developed for urethanes. Most urethanes require application of a mold release agent, a wax, a soap or a silicone, after every shot. Many mold releases cannot be added to the urethane reactant streams or the tanks because they react with the urethane chemicals. These reactions have caused problems of build-up in the mold, even with spray-on mold releases, necessitating periodic shutdowns to scrub the mold surfaces. Some newer systems use a third component stream to Introduce mold release at the mix head. Newer Internal mold release systems permit from 0 to 50 urethane shots to be made between applications of external mold release spray to the tool. Monsanto s nylon RIM system contains an internal mold release that is paintable. In certain applications where a high quality smooth show surface is required on a part, a... 

A major development has been to provide easy release of parts from the mold. Special mold treatments and careful physical removal of parts were required, increasing the cost. PURs now incorporate an internal mold release (IMR) agent that improves part performance and process economics. However, thin-walled, complex parts may require the use of release agents on the mold. Material developments are under way to rectify this situation. 

Forming an optimal molding may require the addition of an external or internal lubricant to the formulation. Lubricants arc added in only small amounts, up to 1 wt %. External lubricants are insoluble in the phenohe matrix resin and are often non- polar materials such as parafiins and waxes. External lubricants act as mold release agents. In contrast, internal lubricants improve melt homogeneity, lower viscosity, and lower injection pressure. Therefore, internal lubricants such as fatty alcohols, fatty acid salts, acid esters, and acid amides must be fully soluble in the phenohe prepolymer [1]. 

Chem. Descrip. Zinc stearate CAS 557-05-1 EINECS/ELINCS 209-151-9 Uses Partitioning agent in dry form where thick uniform coatings are required promotes mold release internal lubricant Features Superior heat stability controlled particle size and high bulk dens, improves dispersion, provides faster, more uniform mixing Regulatory FDA accepted Properties Powd. 

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