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CarCareTruth

Trimethylsiloxysilicate

  • Silicones
  • CAS 68909-20-6
  • IUPAC: trimethylsiloxysilicate

Trimethylsiloxysilicate (CAS 68909-20-6) appears in 3 of the 2,122 car-care products CarCareTruth tracks (as of August 2026).

Low acute toxicity. No GHS classification at consumer-product concentrations. Not a skin or respiratory sensitizer. Used widely in cosmetics, coatings, and personal care products under INCI name 'Trimethylsiloxysilicate'.

Trimethylsiloxysilicate (sometimes called MQ resin or silicone MQ resin) is a silicone polymer used as a film-forming agent in automotive coatings, spray sealants, and cosmetic formulations. It consists of a network of SiO₂ units capped with trimethylsiloxy groups.

In car care products, trimethylsiloxysilicate contributes to film durability and paint adhesion — it forms a more robust, cross-linked network than pure polydimethylsiloxane (PDMS). Its presence in graphene and siloxane spray coatings helps extend durability beyond what PDMS alone provides.

Health: Generally regarded as safe at consumer-use concentrations. Not classified under GHS at product-level concentrations. The INCI (International Nomenclature of Cosmetic Ingredients) lists it as safe for use in cosmetics.

Environment: Silicone resins are persistent but have low bioaccumulation potential and low aquatic toxicity, consistent with the broader silicone polymer family.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
no
Bioaccumulative
no
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
4/5
Purpose: Silicone resin film-former; provides adhesion and durability in spray coatings, glazes, and sealants

Common questions about Trimethylsiloxysilicate

What is Trimethylsiloxysilicate used for in car care?
Silicone resin film-former; provides adhesion and durability in spray coatings, glazes, and sealants
Is Trimethylsiloxysilicate a VOC?
No. Trimethylsiloxysilicate is not classified as a volatile organic compound (VOC).
Is Trimethylsiloxysilicate on California's Proposition 65 list?
No. Trimethylsiloxysilicate is not on California's Proposition 65 list.

3 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.