Internal Mold Release for SMC/BMC

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Key Features

  • Optimized for SMC/BMC compression at 130–160°C and high pressure
  • Synergistic stearate/organic blend for reliable mold release
  • 1.0–2.5 phr dosage for direct SMC/BMC compound incorporation
  • Reduces mold cleaning intervals in high-cycle compression production
  • Does not inhibit cure or affect dimensional shrinkage

This internal mold release agent is specifically optimized for Sheet Molding Compound (SMC) and Bulk Molding Compound (BMC) compression molding processes. In SMC and BMC production, the thermoset resin compound is pressed between matched heated steel molds at temperatures of 130–160°C and pressures of 5–15 MPa. External mold release alone does not provide sufficient release durability and lubrication under these demanding process conditions. This internal release is formulated with a synergistic blend of metallic stearates and organic release agents that provide optimal migration to the resin–mold interface at compression temperatures. Supplied as a concentrated powder blend for direct incorporation into SMC/BMC compound during mixing. Dosage 1.0–2.5 phr in SMC compound. Compatible with standard SMC/BMC resin systems (unsaturated polyester, vinyl ester with filler and glass fiber). Does not inhibit cure or affect shrinkage. Reduces mold cleaning frequency and part surface defects associated with adhesion during compression.

Specifications

ParameterValue
FormPowder concentrate
TypeMetallic stearate / organic release blend
Shelf Life24 months
SMC/BMC Dosage1.0–2.5 phr
Compatible ResinUnsaturated polyester, vinyl ester (SMC/BMC grade)
Process Pressure5–15 MPa
Process Temperature130–160°C

Applications

SMC compression molding productionBMC press molding for automotive and electrical partsHigh-pressure thermoset compression with matched steel moldsThick SMC structural parts (automotive, transport)High-volume SMC/BMC production with minimal mold cleaning

FAQ

Internal release should be added to the SMC resin paste before the glass fiber chopping stage. Mix the powder internal release into the resin paste using the compound mixer until homogeneously dispersed — typically 5–8 minutes of high-speed mixing. Ensure no powder agglomerates remain. Then proceed with glass fiber chopping and maturation. Pre-dispersing the powder in a small amount of styrene monomer before addition can improve distribution in the resin paste.

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