Heat Cured Rubber Silicone

Heat Cured Rubber Silicone is employed in the compression molding press. Specific silicone rubber materials are carefully chosen depending on their intended use, whether they require fire, oil, or heat resistant

What Is Heat-Cured Rubber Silicone?

Heat Cured Rubber also known as HCR (High Consistency Rubber) is silicone elastomer formed from straight chains with extremely high molecular weights. The system can undergo curing using either an organic peroxide crosslinker or a platinum catalyst. HCR exhibits excellent resistance to both temperature and aging.

Chemical structure

Heat cured rubber elastomers are alternatively referred to as High-Temperature Vulcanizing silicone rubber (HTV). They are produced from reactive silicone gums, which are essentially straight chains with exceptionally high molecular weight macromolecules that contain diverse reactive groups. The commonly utilized gums are either partly phenylated or perfluorinated vinylated gums.

Additional materials are incorporated to impart supplementary properties to the HCR, such as fumed or precipitated silicas with a high specific surface area to enhance mechanical characteristics, heat stabilizers, and various other additives including plasticizers or anti-structuring agents. The cross-linking process takes place using organic peroxides in polycondensation systems or platinum catalysts in polyaddition systems.

Characteristics of HCR

Temperature resistance: Heat-cured rubber elastomers possess exceptional characteristics that surpass those of traditional organic elastomers. They demonstrate remarkable mechanical strength even at elevated temperatures, allowing for their utilization within a broad temperature range from -50 °C to +300 °C.

Durable: Silicone rubber is widely favored in various industries when there is a need for retaining the original shape and mechanical strength, particularly in the face of significant thermal stress or extremely low temperatures. Unlike organic rubber, which possesses a carbon-to-carbon backbone, silicone rubber exhibits remarkable resistance to ozone, UV radiation, heat, and other factors that contribute to aging. This exceptional durability in the face of adverse conditions establishes silicone rubber as one of the top choices among elastomers for applications in numerous extreme environments.

The aging resistance: These elastomers exhibit impressive resistance to aging, showcasing their inherent qualities such as chemical inertness, photo-oxidative stability, and the absence of residual reactive groups once they are cured

Chemical resistance: HCR silicone displays remarkable inertness and remains unaffected by the majority of chemicals. This property makes it widely utilized in numerous medical applications, including medical implants. Its biocompatibility, hypoallergenic nature, and non-allergenic characteristics make it suitable for a range of applications such as baby care products and general food contact.

Mechanical properties: At extreme temperatures, properties such as elongation creep, cyclic flexing, tear strength, compression set, dielectric strength (at high voltage), thermal conductivity, fire resistance, and, in some cases, tensile strength can surpass those of organic rubbers in general. However, it should be noted that a few of these properties may still be lower compared to certain specialty materials.

Electrical properties: HCR silicone has great insulating properties

Application of HCR

HCR offers a wide range of color options, and by incorporating a fine silica filler, it becomes possible to create transparent articles suitable for food and paramedical applications.

The addition of various additives provides limitless customization opportunities for HCRs, enabling the development of solutions for a wide range of existing and emerging applications in aerospace, automotive, healthcare, oil and gas, construction, and electronics.

Recent examples include heat transfer additives for electric vehicles, electrically conductive materials for power or consumer electronics, and antibacterial solutions for healthcare applications.

Let’s consider the example of electric vehicles to understand the benefits of HCR. As mentioned earlier, this technology exhibits resistance to both high and low temperatures, and it offers flexibility for incorporating additional properties.

Automotive cable manufacturers have therefore increasingly been using silicone rubber HCR instead of other polymers like TPU/TPE and XLPE. This choice ensures longer aging time under high temperatures and ease of installation in the increasingly compact spaces found in newer-generation automobiles. Cables made with HCR can fulfill the requirements arising from continuous innovation in the electric vehicle industry, particularly for connecting the engine and the battery.

In summary, HCR’s exceptional properties find application in various industrial sectors. It is utilized for sealing and piping in fluid circuitry, including joints for building construction, aeronautical applications, automotive gaskets, boots, and hoses. HCR is also employed for electrical protection purposes, such as safety cables for office equipment, insulators for electrotechnical applications, spark plug boots, and cables and connectors in automotive applications. Additionally, HCR is utilized in food, pharmaceutical, and biomedical applications, including the production of tubes and profiled sections.

To learn more about Heat Cured Rubber Silicone or receive a free quote, contact A1 Silicones representative today.

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