| HS Code | 498272 |
| Productname | Mould Silicone Rubber |
| Producttype | Two-component addition-cure silicone rubber |
| Basematerial | Silicone elastomer |
| Hardnessshorea | 20-60 Shore A |
| Tensilestrengthmpa | 4-8 MPa |
| Elongationatbreakpercent | 300-700% |
| Tearstrengthknm | 15-35 kN/m |
| Densitygcm3 | 1.10-1.25 g/cm3 |
| Color | Translucent or custom color |
| Operatingtemperaturerangec | -40°C to 200°C |
| Mixingratio | 10:1 or 1:1 by weight |
| Curetimehours | 4-24 hours at room temperature |
| Shrinkagepercent | Less than 0.1% |
| Shelflifemonths | 6-12 months |
| Viscositympas | 10000-50000 mPa·s |
As an accredited Mould Silicone Rubber factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Mould Silicone Rubber is packaged in a sealed 1 kg plastic tub, clearly labelled with product name, batch number, and safety information. |
| Container Loading (20′ FCL) | 20′ FCL loaded with palletized, sealed drums/pails of Mould Silicone Rubber, properly secured for dry, compliant ocean transport. |
| Shipping | Mould Silicone Rubber is generally shipped as non-hazardous goods; use sturdy, sealed containers to prevent leakage. Store in a cool, dry, well-ventilated area away from heat and moisture. No special UN hazard class, packing group, or marine pollutant designation is normally required; follow local regulations and manufacturer guidance. |
| Storage | Store Mould Silicone Rubber in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and strong oxidizers. Keep containers tightly closed, clearly labelled, and upright to prevent leakage or moisture ingress. Protect from freezing and contamination. Use original packaging and follow the manufacturer’s shelf-life and temperature recommendations. |
| Shelf Life | Mould silicone rubber typically has a shelf life of 12–24 months when stored unopened in a cool, dry place away from sunlight. |
Condensation-cure RTV-2 silicone with a Shore A 25–30 and a mixed viscosity of 35,000–45,000 mPa·s is specified for precast concrete formliners where repeated stripping from low-slump concrete imposes tear stress at undercut detail lines. The base and catalyst are combined at a 100:3 by weight ratio using a slow-speed planetary mixer at 150 rpm for 4 min, then deaerated in a vacuum chamber at −0.095 MPa for 5 min before being applied to the original pattern. Cure progresses to a demouldable state within 24 h at 23 °C and 50% RH; relative humidity below 20% delays deep-section cure beyond 48 h because condensation cure consumes atmospheric moisture. Formliner surface finish requirements are evaluated under PCI MNL 117 and ACI 551.2R-15, while the cured elastomer is characterised by ASTM D412-16 tensile strength of 4.0–5.0 MPa, ASTM D624-00(2020) tear strength of 20–25 kN/m, and ISO 7619-1:2019 hardness. Concrete is poured at slump 150–200 mm with external vibration at 30–50 Hz; demoulding of architectural cladding panels and precast walls occurs after 24 h compressive strength reaches 15–20 MPa.
When condensation-cure RTV-2 silicone is specified for polyurethane vacuum casting of automotive trial parts, the mould must tolerate exothermic peak temperatures of 45–70 °C during the resin cure without softening at the parting plane. A Shore A 30–35 grade is mixed at a 100:5 by weight base-to-catalyst ratio, producing a pot life of 45 min at 23 °C; after degassing at 5 mbar for 5 min and pouring over the master pattern, the mould is cured for 24 h and post-cured at 60 °C for 4 h to stabilise tear strength at 22–25 kN/m under ASTM D624-00(2020). The downstream vacuum casting cell operates at 30–40 °C and 3 mbar chamber pressure, with polyurethane resin injected into the silicone cavity after the mixture has been degassed; demoulding is conducted after 60 min at room temperature. Traceability under ISO 9001:2015 requires recording the silicone batch number, mixing ratio deviation, and Shore A spot check before production qualification. Addition-cure silicone is not specified for this line unless the polyurethane formulation is screened for platinum catalyst inhibitors such as tin, amines, and sulfur-bearing release compounds, because residual inhibitor at the mould–resin interface can arrest surface cure and produce tackiness on trial parts such as dashboard housings and functional test components.
Addition-cure platinum-catalysed silicone is selected for chocolate shell moulding because condensation-cure systems with organotin catalysts cannot be assumed compliant with repeated food contact without extractables testing under FDA 21 CFR 177.2600 and EU Regulation (EC) No 1935/2004. The two components are mixed at a 1:1 by weight ratio, yielding a pot life of 30 min at 23 °C and a cured hardness of Shore A 20–25. After 24 h cure, the mould is post-cured at 100 °C for 4 h and then washed with 70 vol% ethanol before first food contact. Chocolate is deposited into the silicone cavity at 29–31 °C, vibrated at 10–15 Hz to release entrained air, and passed through a cooling tunnel at 6–10 °C for 12–15 min. Demoulding relies on flexural release at 20–22 °C; moulds are cleaned with non-abrasive detergent and removed from service if crack growth exceeds 5 mm at the cavity edge. Cycle life beyond 200 mouldings is reported in supplier technical bulletins when the cavity is not exposed to temperatures above 200 °C and when high-vanillin or sulfur-containing flavour compounds are excluded from the chocolate filling. Terminal products include chocolate shells, filled chocolates, and sugar confectionery pieces.
In lost-wax investment casting of turbine blades and jewellery, addition-cure RTV-2 silicone tooling is poured against a metal or SLA master to produce wax pattern moulds that must hold contraction within ±0.5% across 80–120 pattern extractions. The A and B components are combined at a 10:1 by weight ratio and vacuum-mixed at 1,200 rpm for 3 min, producing a Shore A 30–35 elastomer with a pot life of 60 min at 23 °C. Post-cure at 80 °C for 4 h is applied before the mould is mounted in a low-pressure wax injection unit operating at 60–90 °C and 0.2–0.5 MPa; the mould is opened after cooling to 20 °C. Dimensional inspection of the resulting wax patterns follows ISO 8062-3:2023 for cast component geometry, while the silicone tool itself is validated by ASTM D412-16 tensile strength of 5.0–6.0 MPa and ASTM D624-00(2020) tear strength of 20–25 kN/m. The operational boundary is platinum catalyst inhibition: trace sulfur from natural rubber backing pads or sulfur-containing mould releases on the master will arrest cure at the pattern interface; aluminium or PTFE release films are specified instead. Terminal products include wax patterns for orthopaedic implant castings, turbine blades, and jewellery investment casting.
Room-temperature condensation-cure silicone block moulds transfer tooling geometry to wet-layup and vacuum-bagged epoxy/carbon components without an autoclave. A Shore A 25 grade is mixed at a 100:4 by weight ratio, giving a pot life of 40 min at 23 °C and allowing hand lamination of glass or carbon plies into the cavity. The applied vacuum of −0.08 MPa is held for 6–12 h during epoxy cure at 25–60 °C; the mould is then released by controlled flexure. Composite part approval requires ASTM D3039/D3039M-17 tensile testing of the cured laminate rather than rubber property testing alone, but the silicone tool is released only after ASTM D624-00(2020) tear strength of 18–22 kN/m and ASTM D412-16 elongation at break of 450–550% are confirmed. The process boundary is the exotherm: thick sections exceeding 10 mm can exceed 80 °C, which condensation-cure silicone tolerates but which accelerates post-cure hardening and reduces tear after repeated cycles. Platinum-catalysed addition-cure silicone is avoided in this cell because carbon fibre sizing or epoxy hardeners containing amines can poison the platinum complex at the tool surface, causing localised uncured patches. Terminal products include carbon fibre drone airframe shells, racing car diffusers, and non-structural composite covers.
At pour temperatures between 70 °C and 90 °C, condensation-cure RTV-2 silicone maintains dimensional stability in candle and soap moulds where the wax or soap feedstock is poured directly onto the cavity face. The base and catalyst are combined at a 100:5 by weight ratio to yield a Shore A 20–25 elastomer with a pot life of 60 min at 23 °C and full cure in 24 h. The mould is degassed at −0.095 MPa for 5 min before the wax pour; after filling, the wax is cooled at 20–30 °C for 20–30 min and removed by flexure. Fragrance oils containing sulfur or amine-bearing compounds can inhibit platinum-catalysed addition-cure silicone, so condensation-cure tooling is specified unless the specific fragrance stock is separately qualified by cure-inhibition testing. Finished soap products fall under EU Regulation (EC) No 1223/2009, and fragrance components must comply with REACH Annex XVII restrictions; the silicone mould itself is controlled under ASTM D412-16 tensile strength of 3.5–4.5 MPa and ASTM D624-00(2020) tear strength of 15–20 kN/m. Terminal products include scented candles, decorative soap bars, and wax melts.
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Mould silicone rubber is a two-part, room-temperature-vulcanising (RTV) elastomer compounded for direct-contact tooling against original patterns and for repeated casting of low-viscosity thermosets. Commercial grades are classified under ASTM D1418 as VMQ or PVMQ, with mixed viscosity at 25 °C spanning 4,000 mPa·s to 60,000 mPa·s. Cured hardness is supplied from 10 Shore A to 40 Shore A, with tensile strength of 4 MPa to 8 MPa for addition-cure grades and 2 MPa to 4 MPa for condensation-cure grades when tested according to ASTM D412-16(2021). A 1:1 addition-cure grade with 10,000 mPa·s mixed viscosity is typically selected for thin-section architectural details, while a 10:1 grade with 30,000 mPa·s mixed viscosity is used for stiff undercut tooling. Common application environments include open-block moulds for polyurethane casting resins, skin-contact prosthetic appliances, architectural precast concrete formliners, and wax pattern tools for investment casting.
Condensation-cure mould silicone rubber is usually supplied as a base polymer with a 100:5 or 100:10 catalyst ratio and crosslinks through a tin-mediated reaction that releases low-molecular-weight alcohol. Linear shrinkage after 7 days at 23 °C is commonly specified at 0.3 % to 0.6 %, which limits its use where pattern dimensions must be held within ± 0.1 mm over a 200 mm span. Addition-cure systems use a platinum complex catalyst, mix at 1:1 or 10:1 by weight or volume, and exhibit linear shrinkage below 0.2 % in published datasheets. Tear strength measured under ASTM D624-00(2020) for a 2 mm die C specimen ranges from 8 kN/m to 30 kN/m for addition-cure grades; condensation-cure equivalents are typically 10 kN/m to 20 kN/m. Hardness is measured at 3 s delay under ASTM D2240-15(2021); soft grades below 10 Shore A may show a drop of 2–4 points at 15 s because of viscoelastic relaxation. The platinum cure is inhibited by elemental sulfur, organotin compounds, amine-containing epoxies, and certain polyvinyl chloride stabilisers; contact with these materials produces a tacky surface layer containing residual reactive vinyl groups. Condensation-cure grades remain preferred when pattern substrates contain inhibiting species or when deep-section cure at 23 °C must proceed without external heat.
On production lines, mixed material is degassed in a vacuum chamber at 5 kPa to 10 kPa absolute for 2 min to 5 min; visual collapse of the froth is used as the operator release criterion. Meter-mix equipment with positive-displacement pumps and static mixers is specified for 10:1 addition-cure grades to maintain a ratio tolerance of ± 2 %. Viscosity doubling under 23 °C at 1 s⁻¹ is recorded on a rotational rheometer; typical pot life ranges from 6 min to 90 min for platinum grades and from 20 min to 120 min for tin grades. Thixotropic modifications prevent flow on vertical patterns; a suitable brushable grade shows slump below 2 mm at a 4 mm wet film thickness on a vertical glass panel after 5 min at 23 °C. The yield stress produced by fumed silica at loadings of 20 wt% to 40 wt% is sufficient for brush-on application without solvent addition. High-consistency materials with filler loadings above 45 wt% raise mixed viscosity above 60,000 mPa·s and complicate vacuum degassing.
Post-curing is recommended for addition-cure grades at 80 °C to 120 °C for 4 h to 8 h; published supplier data commonly report a reduction in compression set to 10 % or below after 22 h at 175 °C under ASTM D395-18 Method B. Post-curing also drives off volatile cyclic siloxanes, reducing mass loss from 0.5 % to 1.5 % for ambient-cured platinum grades to below 0.3 % after 4 h at 100 °C. Unlike high-consistency silicone rubber or liquid silicone rubber processed by injection moulding at 160 °C to 200 °C, mould silicone rubber cures at ambient or mild oven temperatures and is intended for manual or low-pressure metered dispensing. This eliminates the need for a heated mould but reduces ultimate tensile strength relative to LSR, which may reach 12 MPa. The polymer backbone is a polydimethylsiloxane with vinyl methylsiloxane crosslink sites; filled grades contain fumed silica or ground quartz to adjust mechanical properties and sag resistance.
Compared with polyester-polyol polyurethane tooling elastomers, mould silicone rubber exhibits a cured surface energy of 20 mN/m to 24 mN/m, whereas polyurethane systems typically exceed 35 mN/m. This difference reduces wetting by polar casting resins but also means that silicone moulds are not readily bonded to rigid support shells without a silicone-to-metal adhesive. Polyurethane elastomers can provide higher tensile strength, often 20 MPa to 50 MPa, and greater tear resistance in rigid grades, but they introduce moisture sensitivity during cure and can embrittle at sustained temperatures above 80 °C. Natural latex tooling produces high elongation and low material cost but exhibits poor resistance to ozone, ultraviolet exposure, and hydrocarbon-based release agents; linear shrinkage of latex can exceed 2 % during drying. In contrast, addition-cure VMQ retains elastomeric behaviour across −50 °C to 200 °C continuous service and does not require plasticiser migration to maintain flexibility. The low surface energy also interferes with post-applied coatings; silicone moulds are usually supplied as a self-coloured, unpainted tool surface.
| Property | Addition-cure mould silicone | Condensation-cure mould silicone | Polyurethane tooling elastomer | Test method |
|---|---|---|---|---|
| Hardness | 10–40 Shore A | 15–45 Shore A | 60 Shore A–80 Shore D | ASTM D2240-15(2021) |
| Tensile strength | 4–8 MPa | 2–5 MPa | 20–50 MPa | ASTM D412-16(2021) |
| Elongation at break | 300–700 % | 150–500 % | 10–100 % | ASTM D412-16(2021) |
| Tear strength | 15–30 kN/m | 10–20 kN/m | 20–100 kN/m | ASTM D624-00(2020) |
| Linear shrinkage | <0.2 % | 0.3–0.6 % | 0.1–0.5 % | Supplier QCM |
| Continuous service temperature | −50 °C to 200 °C | −50 °C to 150 °C | 20 °C to 80 °C | Supplier data |
Epoxy tooling resins provide a rigid support shell but cannot reproduce elastomeric demoulding. Alginate and silicone are both used for body casting; alginate is single-use and has tensile strength below 0.5 MPa, while mould silicone can be reused for 30 to 100 demouldings depending on resin chemistry and undercut severity. Published data for the upper limit of cycle life in highly filled gypsum systems is limited because wear proceeds by surface abrasion and release-agent consumption rather than by bulk polymer degradation. Polyurethane resins cured with aromatic isocyanates can yellow upon light exposure; the silicone mould does not contribute to this discoloration because it contains no aromatic isocyanate or amine reactive groups. However, residual tin soaps from condensation-cure moulds can migrate into adjacent cast polyurethane surfaces if the mould is not fully post-cured, producing local surface haze.
In vacuum-assisted casting of unfilled or mineral-filled polyurethane resins, mould dimensional error is dominated by elastomer shrinkage rather than by resin exotherm. Addition-cure mould silicone with linear shrinkage below 0.1 % is therefore specified for tools that must reproduce a 300 mm feature within ± 0.15 mm. The mixed silicone is often poured under vacuum in a chamber at 5 kPa to 15 kPa to remove entrained air before the resin is introduced. The exotherm of a 200 g casting in a 500 g mould can raise the interface temperature to 45 °C to 65 °C for fast-gelling urethane systems; the silicone tool is typically post-cured at 100 °C for 4 h before first use to stabilize the polymer network and minimise initial drift. Demoulding is carried out with polytetrafluoroethylene dry-film release agents at 5 µm to 15 µm dry film thickness for production runs exceeding 50 cycles. Silicone’s high coefficient of friction against rigid polyurethane makes undercuts prone to localised tearing unless a PTFE-based release agent is applied; the release film also reduces surface gloss variation on cast parts.
For wax pattern tools used in investment casting, condensation-cure mould silicone with 15 Shore A to 25 Shore A hardness permits removal of intricate wax patterns without damage to fragile core features. The tool is often reinforced with a rigid epoxy or polyurethane backing shell of 5 mm to 10 mm thickness after the silicone face coat reaches 2 mm to 4 mm. In architectural precast concrete formliners, addition-cure grades with 30 Shore A to 40 Shore A hardness and tear strength above 20 kN/m are used because the formliner must withstand 20 cycles to 50 cycles of concrete casting without delamination. For larger concrete formliners, a base coat of 2 mm to 4 mm is followed by a filled backing layer to control total cost and to improve dimensional stability under hydrostatic pressure.
At ambient temperature, mould silicone resists fresh water, calcium sulfate slurries, and many polyurethane casting resins. It swells in low-polarity solvents; immersion in toluene can increase volume by 100 % to 200 % depending on filler content, and the solvent uptake reverses over 24 h to 72 h after evaporation. Moulds used with solvent-borne epoxy gel coats should be tested for dimensional recovery because retained solvent lowers local hardness by 5 to 10 Shore A points and increases surface tack.
Platinum inhibition is concentration-dependent. Trace sulfur compounds at 10 ppm can produce a tacky interface even when bulk cure appears complete within 24 h at 23 °C. In production lines using reclaimed rubber pattern compounds, localised inhibition has been observed when sulfur crosslinker residues exceed 50 ppm by energy-dispersive X-ray fluorescence screening of the pattern surface. Pre-cleaning with a 70 % ethanol/water solution and a polyvinyl alcohol barrier coat is a common control measure.
| Requirement or property | Standard or clause | Typical condition |
|---|---|---|
| Food-contact rubber articles | 21 CFR 177.2600 | Supplier-validated post-cure |
| Cytotoxicity | ISO 10993-5 | Prosthetic skin-contact |
| Volatile outgassing | ASTM E595 | 200 °C for 2 h |
| RoHS restricted substances | IEC 63000 / RoHS Directive 2011/65/EU | Homogeneous material |
| REACH SVHC declaration | Regulation (EC) No 1907/2006 | Article 33 |
Compliance documentation for skin-contact or food-contact grades is limited to supplier-validated formulations. Post-cured platinum-catalysed mould silicone can be formulated to meet 21 CFR 177.2600 for rubber articles intended for repeated food-contact use; cytotoxicity evaluation may follow ISO 10993-5 for prosthetic applications. Electrical and electronics tooling requiring low volatile siloxane content should specify a post-cure at 200 °C for 2 h and verify the grade against ASTM E595 if outgassing is critical. Uncured mould silicone should be stored between 15 °C and 25 °C in sealed containers; exposure to humidity above 60 % can increase condensation-cure catalyst activity and shorten pot life. Frozen storage is not recommended because filler settling and viscosity hysteresis can occur after thawing. Condensation-cure grades are not recommended for continuous contact with acetic acid, strong alkali, or solvent-laden casting resins because tin catalyst residues and silanol end groups can accelerate depolymerisation at the mould surface. Addition-cure grades stored in contact with sulfur-containing modelling clay or latex patterns may exhibit incomplete cure even after extended heating.
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