Silicone Rubber

Innovative Silicone Elastomers Challenge Harsh Environments

Silicone Products

YONGRUI（Ahyrsilicon）is one of ten silicone rubber manufacturers in China, with Anhui Province as the main production base and equipped with R&D laboratories. As a global manufacturer in the silicone field, Yongrui always provides high-quality customized silicone rubber solutions based on end-user usage and performance design requirements. In order to better understand the needs of customers, we have set up sales offices in Guangdong, Anhui, Shanghai, and Xiamen.

High melting point silicon exists in nature, common natural compounds are silicon dioxide and silicates (quartz stone, feldspar, mica). Compared with quartz, which is not easy to form and process, organic silicon not only has a unique chain structure with alternating siloxane bonds but also Si atoms link CH3 or replace hydrocarbon organic groups and different polymerization methods, giving it distinctive properties, so as to apply to different fields. Usually, the form of these products can be liquid or oily, or even solid, depending on the purpose and method of use.

Silicone rubber is the general-purpose elastomer specified by design engineers for the vast majority of industrial and medical component manufacturers, and it is often a high-performance silicone material that meets the needs of critical applications.

Yongrui generally uses polysiloxane whose molecular chain contains vinyl, hydroxyl, and other activist groups to make silicone rubber, and prepares silicone with predictable properties for users to use. The core products are as follows:

Why use silicone rubber in product design?

What are the advantages of silicone rubber that many designers continue to choose it? And this demand trend continues to expand. The four elastomers are introduced below from multiple dimensions such as chemical structure, curing system, and molding process.

Liquid silicone rubbers (LSRs, LIM, typical 2-part system, short-term fully automatic operation)

Our LSRs series are polymers with a lower degree of polymerization (usually above 1000). They are usually linear polysiloxanes containing vinyl groups, in the appropriate platinum complex under the catalysis of a material catalyst, it is cross-linked with oligosiloxane containing hydrogen bonds. They have short polymer chains before curing and have excellent fluidity. That is, their advantages of low molecular weight and low viscosity are different from other types of silicone rubber, so they are destined to be suitable for special injection machines and easy to realize fully automated molding. Compared with traditional processing and molding methods, injection molding provides unlimited power to promote productivity.

They are cured under medium temperature and low-pressure conditions and are a kind of heat-curing material. And this high-purity elastomer withstands extreme environments and offers the following benefits:

❐ Faster curing, saving 35%-50% crosslinking time.
❐ Excellent fluidity is friendly to the mold and can easily reach all the gaps in the mold.
❐ The hardness ranges from Shore 5-90A, and the design freedom is large, making it possible to design and develop applications with extremely complex components.
❐ Any color can be adjusted to maximize the realization of the personalized value of the color.
❐ Free of mixing, post-curing, or cumbersome processing procedures, it has cost advantages and provides a feasible solution for efficient production.
❐ Compared with ordinary silicone rubber, the price of manufacturing raw materials is slightly higher, but there is no burr during production, eliminating waste from the source, and the total cost is highly controllable, especially suitable for the production of small parts.
❐ LSR not only satisfies one-time molding but also can be used to achieve secondary molding, which can save the cost of secondary assembly that was previously necessary.

LSR is also an excellent choice for applications in specific fields that require wide operating temperature, high transparency, soft touch, and low allergen requirements, such as mother and baby, medical treatment.

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High Consistency Rubber (HCR) or High-Temperature Vulcanized (HTV) silicone rubber

Our high consistency rubber or heat-cured rubber series are long-chain polymers with a medium degree of polymerization, usually, they contain 0.1%-0.3% unsaturated vinyl groups and organic groups with special characteristics to meet applications with different performance requirements. Unlike LSR, they need to be crosslinked at high temperatures and there are many kinds of catalysts to choose from, which can be peroxide (usually DBPH) or platinum. The usual use of peroxide cure systems is associated with technical grade silicone rubber and typically requires a second bake to eliminate residual volatile or toxin components. Platinum-catalyzed ones are usually related to food or animal contact. Their molding process can be common molding, extrusion, or preheated injection molding.

This kind of Heat-cured elastomers gains market acceptance with the following advantages:

❐ The processing equipment is simple and low-cost.
❐ Manufacturing raw materials are highly optional and inexpensive.
❐ At present, it has the widest application scenarios and often exists in rubber hoses, high-voltage cables, and special-shaped rubber strips.
❐ The cost of using molding molds is low, about a quarter of that of injection molding molds.
❐ Achieve production flexibility, suitable for small batch production of products (LSR used for injection molding often requires a long debugging time and wastes a lot of rubber during debugging).

One-part (RTV-1) or two-part (RTV-2) room temperature vulcanizing silicone rubber

Our RTV silicone rubber series are chain polymers with low to high degrees of polymerization, usually, they contain active functional groups, such as hydroxyl groups. RTV-1 silicone relies on water molecules in the atmosphere to trigger the condensation reaction. RTV-2 silicones use organotin or platinum catalysts to initiate cross-linking. They are formed without complex construction equipment, most of them are made from local materials, and they are highly adaptable to occasions ranging from electronics to aerospace industries. They are usually associated with the manufacture of adhesives, sealants, coatings, moulding materials.

Key Properties of Silicone Rubber

Silicone rubber differs from other elastomers in its unique inorganic siloxane bond structure. This special chemical structure provides:

☆ Excellent scratch resistance
☆ Super high-temperature resistance (-60°-+250°)
☆ Resistant to -100°C low temperature (specially formulated)
☆ Resistance to natural sunlight
☆ Stable electrical performance
☆ Long-term stable biocompatibility which does not cause human skin allergies

The combination of Si-O-Si main chain and hydrocarbon group endows elastomers with super strong performance, which is mainly reflected in :

▣ Very low compression set
▣ Exhibits superhydrophobicity and superlubricity
▣ Excellent low surface tension capability
▣ High-Reliability Bonding Performance
▣ Optically transparent appearance
▣ Remains flexible in cold environments and is virtually unaffected by temperature changes

Key industry applications of silicone rubber

Silicone rubber serves different industrial applications due to its many unique properties, and the options range from lighting to medical. Yongrui provides a variety of practical and safer silicone solutions to meet the application of continuous innovation projects. A few key areas are highlighted below:

● LED lighting industry：The demand for high-brightness, high-efficiency LED lighting is growing rapidly. In order to improve the overall performance, reliability, and manufacturing cost of products, designers have been looking for LED solutions with light and heat stability, high transparency, and high plasticity. Our supply of optical-grade liquid silicone rubber offers solutions for manufacturers looking to improve LED light output and luminaire reliability. The silicone rubber material has higher air tightness and high-temperature stability, which protects the LED electrodes from moisture attack and other chemical substances, and greatly reduces the yellowing, blackening and physical attenuation of the LED. In addition, the injection-reactive silicone rubber material also has excellent plasticity, which helps the LED structure to achieve more complex shapes. Common applications include light pipes, secondary optics, and LED packaging.

● Electric Vehicle Industry: With the explosive growth of new energy vehicles, the large carrying capacity of electric vehicle cables puts forward higher stability and reliability requirements for manufacturing materials. Because of its long-lasting high-temperature resistance, high flexibility, low-pressure change, Self-lubricating, and strong flame retardancy, silicone rubber is the best material for making cables, connector seals, and engine gaskets. Yongrui has developed a platinum-catalyzed silicone solution with high-temperature resistance, low surface friction coefficient, and controllable self-bleeding rate, which is specially used for the production of high-voltage connector seals and high-voltage cables for electric vehicles.

● Electrical equipment industry: The rapid development of industry means that the demand for electricity has increased, which has promoted the demand for high-voltage power transmission and transformation equipment industry. Traditional glass and ceramic materials cannot meet the higher electrical performance requirements of electrical equipment. The vulcanized silicone rubber has no cross-linkable active groups, and its chemical bonds are not broken and are always consistent, so it has the ability to withstand high-energy radiation for a long time and exhibits extremely high resistance to weathering and aging. It also has excellent long-term resistance to dirt and hydrophobic migration, electrical corrosion resistance, and rain flash resistance. Yongrui provides liquid silicone rubber solutions for cable accessories. The solution has a tracking resistance rating of 1A4.5. Other applications include high voltage insulators, composite surge arrester jackets, shed sheds, and other large bushings.

● Healthcare Industry： Healthcare is a continuously growing and demanding industry. Silicone rubber, which satisfies both inertness and compatibility and is easy to finely process, naturally becomes the material of choice for medical applications. Our silicone elastomer solutions meet USP Class VI requirements. Typical applications include dental impressions, and various types of tubing (pump tubing, connecting tubing, cannula, catheter, drainage tube).

Our core advantages of silicone rubber materials:

Yongrui has 13 years of organic silicon technology accumulation, the combination of key additive synthesis technology and a mature formulation process to ensure the stability and traceability of each batch of products. Every step of our innovation is to meet more design needs and performance requirements of customers. We regard every customer as a strategic partner, and we are committed to assisting customers in developing customized silicone products with high performance and continuously providing high-value innovative solutions that meet customer expectations, such as baby care, medical health, and industrial fields.

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