Platinum-cured silicone rubber, also known as addition cure silicone rubber, is a liquid silicone rubber compound vulcanized at room temperature using platinum catalysts. This ultra-clean, high-purity, translucent silicone elastomer requires the mixing of silicone polymer and catalyst to initiate the curing process. With a simple 1A:1B weight or volume mixing ratio, this low-viscosity liquid silicone is easily mixed and poured. The curing process can be greatly accelerated through heat curing.

Platinum-cured liquid silicone offers fast cure, a range of hardness options (0-50 Shore A), and can achieve an infinite number of color effects by adding silicone pigments. These products exhibit extremely low shrinkage and high physical properties. They have been tested to meet the requirements of federal regulations FDA extraction test CFR 177.2600 and can be safely used in contact with food.

platinum cure silicone

Curing Principle: Platinum-catalyzed addition curing, also known as hydrosilylation, is a reaction between cross-linkers rich in Si-H and vinyl-functionalized polysiloxanes. Unlike tin-cured silicone, the cure is initiated by the platinum catalyst and not moisture, so there are no issues with section thickness. Two-part systems do not release reaction by-products, allowing them to cure in closed environments.

Composition: The primary constituents of addition-cure silicone include 107# base rubber (room temperature vulcanized methyl silicone rubber), hydrogen silicone fluid (Polymethylhydrosiloxane), vinyl silicone fluid, platinum catalyst, inhibitor, and cross-linking agent. Part A contains the catalyst in the form of a platinum complex, while part B contains the cross-linker (H-siloxane).

addition cure silicone

Features

Technical Parameter

Product NameHardnessMixing RatioViscosityPot LifeCure TimeTear Strength
RTV-41000 A1A:1B5,000 cps40 mins4 hrs≥3.0 N/mm
RTV-41055 A1A:1B5,500 cps40 mins4 hrs≥12.0 N/mm
RTV-411010 A1A:1B6,000 cps40 mins4 hrs≥13.0 N/mm
RTV-411515 A1A:1B6,500 cps40 mins5 hrs≥15.0 N/mm
RTV-412020 A1A:1B7,500 cps40 mins5 hrs≥17.0 N/mm
RTV-413030 A1A:1B10,500 cps40 mins6 hrs≥18.0 N/mm
RTV-414040 A1A:1B21,000 cps40 mins8 hrs≥17.0 N/mm
RTV-415050 A1A:1B33,000 cps40 mins10 hrs≥6.0 N/mm
platinum cure silicone material

Application Examples

Platinum-cured silicone is food-grade silicone material suitable for making baking molds and trays, ice trays, casting butter, chocolate and other applications used to produce food. They are perfect for intricate detail molds and castings that require minimal shrinkage and have a long life span. These silicones are commonly used in highly accurate prototyping and model-making applications as well.

Addition-cure silicone should be used in applications requiring highly accurate dimensional reproduction of an original part, such as in rapid prototyping. They are also suitable for applications requiring higher temperature tolerance or where repetitive releases are necessary. Additionally, they are effective for creating simple one or two-piece block molds.

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Attention

  1. Please make sure to use part A and part B of the same model and batch.
  2. It is recommended to perform a small test application to determine the suitability of the product before using large quantities for your project.
  3. After mixing Part A and Part B, it is important to stir the mixture thoroughly to prevent any uncured portions from remaining.
  4. Do not use platinum-cured silicone at temperatures below 15°C (60℉), as it may not cure or may be difficult to cure properly.
  5. Platinum-cured silicone can be heated to accelerate curing. However, it is important to keep in mind that decreasing the cure time will also reduce the work time available for application and manipulation.
  6. Continued use of platinum-cured silicone at temperatures above 200°C (392°F) may result in a loss of elasticity over time. Therefore, usage at temperatures above 250°C (482°F) is not recommended.

Addition cure silicone contains platinum catalysts that may inhibit crosslinking when in contact with certain materials. When in doubt, a patch test should be conducted to determine compatibility. The following is a list of materials that may potentially inhibit the curing process:

  1. Sulfur-cured organic rubber systems (modeling clays, natural rubber, polysulfide rubber, latex rubber and adhesives, sulfur).
  2. RTV-2 silicone elastomers catalyzed with metal salts, e.g. tin compounds.
  3. PVC stabilized with tin salts and additives.
  4. Amine-catalyzed epoxy resins, e.g. UV curable resin for 3D printing.

To prevent inhibition it is usually helpful to coat the pattern with a clear acrylic lacquer or primer. Do not use polyurethane or latex.

addition cure silicone rubber

Safety

The A and B components of platinum-cured silicone are considered non-toxic and can safely come into contact with human skin. Therefore, no special treatment precautions are required. However, if gloves are desired, please use vinyl gloves only, as latex gloves may inhibit the curing process of the rubber.

For applications involving food, it is important to wash the cured mold with warm water and soap before use.

If accidental eye contact occurs, rinse thoroughly with water and seek medical attention.

Adult supervision is required and keep out of reach of children.

platinum cure silicone rubber

Storage

Store the material at room temperature (between 15-25°C / 60-77°F), and note that the product shelf life is 24 months from the date of manufacture. Storing it at higher temperatures could reduce the usable shelf life of any unused material. If the storage time extends beyond the date specified on the certificate of analysis, it doesn't necessarily mean that the product is no longer usable. However, in such cases, it's important to check the properties required for the intended use to ensure quality assurance.

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