MQ Silicone Resin (M-Unit + Q-Unit Branched Silicone Resin): Reinforcement Resin for High-Modulus Silicone and Silicone PSA Tackifier
SEMITECH MQ silicone resin is the highly-branched silicone resin built from M-units (trimethylsilyl from HMDS) and Q-units (silicate from TEOS). Used as reinforcement filler in LSR/HCR elastomer, tackifier in silicone PSA, and carrier resin in release coatings. Solid powder + 60% xylene/toluene solution forms.
Contents
| M:Q ~0.6–1.0 | 2,000–10,000 | 60% solution |
|---|---|---|
| Mole ratio | MW (g/mol) | Standard form |
Chemistry & Specifications
M (Me₃Si) endcaps + Q (silicate) core; soluble in toluene/xylene/IPA; brittle solid in dry form.
MQ resin has a Q-unit-rich silicate core capped by M-unit trimethylsilyl groups. M:Q ratio (0.6–1.0) controls MW and properties — higher M:Q gives lower-MW resins (3,000–5,000 g/mol) for PSA; lower M:Q gives higher-MW (8,000–10,000 g/mol) for hard coatings.
SEMITECH supplies powder (≥98% active, ≤0.5% water) and 60% solution in xylene or toluene. CoA includes M:Q ratio (NMR/FT-IR, ±0.05), MW (GPC, ±15%), residual silanol (≤0.5%).
Reinforcement Mechanism: MQ as Functional Filler in Silicone Elastomer
MQ resin co-disperses with PDMS, provides Q-rich rigid domains that enhance tensile + tear; alternative/complement to fumed silica.
MQ resin partitions into the silicone matrix as 5–50 nm rigid domains, providing reinforcement through molecular-scale dispersion rather than discrete particles. At 15–35% loading, it delivers tensile 10–18 MPa with lower compound viscosity than fumed silica. Many formulations blend both — silica at 15–20% plus MQ at 5–15%.
- Loading 15–35% MQ resin in LSR — high-modulus medical, automotive, industrial sealing applications
- Loading 30–60% MQ resin in silicone PSA — tackifier for skin-contact medical, electronic assembly, removable industrial
- Loading 5–20% MQ resin in HCR gum — supplementary reinforcement alongside fumed silica primary filler
- Loading 50–80% MQ resin in hard coating — silicone hard coating for plastic substrates, antifog optical surfaces
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Applications: PSA Tackifier, LSR Reinforcement, Hard Coating, Defoamer Resin
Silicone PSA tackifier (largest), high-modulus LSR reinforcement, silicone hard coating, defoamer resin component.
Silicone PSA tackifier is the largest application — skin-contact medical adhesive, electronic assembly adhesive, and removable industrial labels. MQ at 30–60% with low-MW silicone forms PSA with biocompatibility, removable adhesion, and −40°C to +200°C service range.
High-modulus LSR reinforcement at 15–35% targets tensile 12+ MPa for automotive seals and medical devices. Silicone hard coating at 50–80% cures to a glassy scratch-resistant film on PMMA, PC, PET substrates. Defoamer resin at 1–5% improves spreading kinetics in silicone defoamer compounds.
Procurement, Storage and Quality Control
CoA per shipment with M:Q ratio + MW verification; powder + 60% solution forms; 24-month shelf life.
Powder in 25 kg fibre drums; solution in 200 kg steel drums. MOQ 25 kg (powder) or 200 kg (solution). Lead time 4–6 weeks to Asia for stocked grades, 6–8 weeks to Europe/North America. Powder is non-flammable; solution requires Class IB flammable storage (xylene/toluene). REACH-registered; FDA 21 CFR 175.300 listed; USP Class VI available on request.
MQ Silicone Resin Specification Sheet
SEMITECH stocked grades; CoA per batch with M:Q ratio and MW verification.
| Property | Powder Form | 60% Solution Form |
|---|---|---|
| Form | White-to-pale-yellow brittle solid | Pale-yellow viscous solution |
| Active resin content | ≥98% | 60.0 ± 0.5% |
| M:Q mole ratio | 0.6–1.0 (grade-dependent) | 0.6–1.0 (grade-dependent) |
| Molecular weight (Mw) | 3,000–10,000 g/mol | 3,000–10,000 g/mol |
| Solvent | None (solid) | Xylene or toluene |
| Water content | ≤0.5% | ≤0.1% |
| Residual silanol | ≤0.5% | ≤0.3% |
| Solubility | Soluble in toluene, xylene, MEK, IPA | Diluted with toluene, xylene, MEK |
| Density (25°C) | ~1.10 g/cm³ (powder) | 0.95–1.00 g/cm³ (solution) |
| Viscosity (25°C) | N/A (solid) | 50–200 cP |
| Flammability | Non-flammable (solid) | Class IB flammable (xylene/toluene) |
| Glass transition Tg | ~100°C | N/A |
| Packaging | 25 kg HDPE-lined fibre drum | 200 kg HDPE-lined steel drum |
| Shelf life | 24 months sealed below 30°C | 24 months sealed below 30°C |
FAQ
+When should I add MQ resin to my LSR formulation, and at what loading?
Add when you need tensile 12+ MPa, elongation 250%+, and tear 25+ N/mm. Start at 15% MQ alongside existing fumed silica (15–20% silica + 15% MQ). Some specialty formulations use 35% MQ alone for lowest compound viscosity at higher cost.
+How is silicone PSA different from acrylic or rubber-based PSA?
Silicone PSA offers extreme temperature range (−40°C to +200°C+), skin biocompatibility for medical applications, and clean-removal without residue. Trade-offs: 5–10× more expensive per m² than acrylic PSA, and bonds to fewer substrates.
+Powder vs 60% solution — which form is right for my application?
Powder for HCR/HTV mill-mix compounding, cost optimisation, and shipping economics. Solution for LSR formulation (ready-to-use), PSA manufacture, hard-coating application, and small-scale R&D.