What Is Platinum-cured Silicone?

What is Platinum-cured Silicone？

Platinum-cured silicone is not silicone rubber made from platinum. Silicone rubber needs a curing agent or catalyst to harden. When a platinum compound is used as the curing catalyst, the material is called platinum-cured silicone. It is also known as addition-cure silicone.

The silicone rubber used in molding is usually a thermoset material. After the material is placed into a mold, heat and pressure are applied. A chemical reaction takes place inside the mold. The silicone molecules crosslink and harden into the final rubber part.

General silicone rubber often uses organic peroxide as the curing agent. Platinum-cured silicone uses a platinum compound instead. This difference affects the curing reaction, odor level, processing behavior, and final material cleanliness.

The odor often found in general silicone rubber does not come from the silicone itself. It usually comes from the organic peroxide curing agent and its decomposition by-products.

Platinum-cured silicone has very little odor. It can also offer good tear strength and low compression set. Silicone rubber is already a safe and stable material, but platinum-cured silicone is cleaner because it does not use organic peroxide as the curing agent. This makes it suitable for food, medical, and hygiene-related products.

Properties Of Platinum-cured Silicone

The table below compares platinum-cured silicone with general silicone rubber that uses organic peroxide as the curing agent.

Compared with peroxide-cured silicone, platinum-cured silicone cures at a lower temperature. This means it needs less heat to complete the curing reaction.

It is also more sensitive. Heat, mixing conditions, or contact with certain substances can affect the cure. Compounds that contain sulfur, phosphorus, nitrogen, or tin may cause cure inhibition. If these substances are mixed into the material or touch the material surface, the silicone may not cure properly. The surface may also remain tacky.

Platinum-cured silicone also has a shorter usable life after the catalyst is mixed in. The time between mixing and molding is limited. This makes the material harder to process than general peroxide-cured silicone.

In production, platinum-cured silicone needs good process control. It is not a material that should be handled without experience.

Features Of Platinum-cured Silicone

The main features of platinum-cured silicone include:

1. It uses a platinum catalyst as the curing system.
2. It cures at a lower temperature, usually around 120 C.
3. It has almost no odor.
4. It is sensitive to cure inhibition, so processing control is important.
5. It has a short pot life after the curing system is mixed.
6. It produces very little outgassing after molding, making it a clean and safe material choice.

These features explain why platinum-cured silicone is common in LSR injection molding and selected silicone compression molding projects.

Applications Of Platinum-cured Silicone

Medical Silicone Products

Platinum-cured silicone is widely used in medical silicone products. For medical parts that contact the human body, blood, body fluids, or drug solutions, platinum-cured silicone is often preferred. This is especially important when the rubber part may contact fluids that later enter the body.

From a practical point of view, many medical-grade silicone rubber products are made from platinum-cured silicone. This is one reason it is often selected for medical silicone molding.

Food-contact Silicone Products

General silicone rubber can also meet many food safety requirements. However, peroxide-cured silicone may have a distinct odor. This can be a problem in food-related applications where smell matters.

In some cases, parts made from general silicone rubber may need to be boiled in water before use to reduce odor. Platinum-cured silicone is often used for food and hygiene products because it is safe, clean, and almost odorless. It is a strong material option for food-grade silicone molding.

Products That Need Low Temperature Silicone Molding

Platinum-cured silicone is also useful when silicone rubber must be molded at a lower temperature.

For example, in overmolding, silicone rubber may be bonded or molded together with hard plastic parts such as PC or nylon. These plastics may not tolerate high molding temperatures well.

Because platinum-cured silicone can cure at a lower temperature, it is suitable for insert molding processes where the inserted plastic part must be protected from heat damage. This makes it a good choice for integrated silicone-and-plastic components.

What to Consider

Platinum-cured silicone is clean and useful, but it needs careful processing.

The material should be stored under the conditions recommended by the supplier. Many platinum-cured silicone compounds require refrigerated storage. Once the curing system is mixed, the usable time is short, so production planning matters.

Tooling, mixing equipment, release agents, pigments, and inserts should also be reviewed for cure inhibition risk. Sulfur, phosphorus, nitrogen, tin, and some contaminated surfaces can interfere with the platinum addition reaction.

For this reason, the material choice should be reviewed together with the product structure, production process, and end-use requirements. If the project involves food contact, medical contact, low odor, low volatile content, or silicone-to-plastic insert molding, platinum-cured silicone is often worth considering.