New refractory material - ceramic silicone rubber

In recent years, with the rapid growth of urban population, high-rise buildings, large shopping malls, medical institutions, airports, the importance of fire safety has become increasingly prominent. So in the fire accident, how to ensure that electricity and communication in a certain period of time to maintain smooth, reduce casualties has become an urgent problem to be solved in the contemporary world. Under the continuous research of scientists, the ceramic silicone rubber came into being. Ceramic silicone rubber material is a new type of polymer refractory material, which retains all the characteristics of silicone rubber at room temperature. With the improvement of people's awareness of safety and fire protection, its application field is also constantly extending.

Characteristics of ceramic silicone rubber

1. Form self-supporting ceramic body in flame

When the rubber material containing inorganic filler is exposed to flame, the rubber degrades or burns, and the inorganic residue or ash with low strength is left after the degradation or combustion products are volatilized. These residues are usually not cohesive or self-supporting, or even broken into particles or powder, and therefore have no fire protection effect. When the special design formula of ceramic rubber exposed to the flame, depending on the rubber variety and formula adjustment, can produce ceramics in the range of 350 ~ 800℃ or above, burning into porous self-supporting ceramic body, in 650 ~ 1000℃ high temperature flame, a certain time (0.5 ~ 2h) can maintain the integrity of the structure, It can play the effect of "passive fire prevention" well and win precious time for fire safety.

2. It has a certain strength and good thermal shock resistance

After ceramization, the sintered body is relatively hard, and there is a ceramic sound when hitting, and there is a certain flexural strength and compressive strength. The flexural strength of ceramic silicone rubber specimen is much higher than that of ordinary silicone rubber, and it increases obviously with the increase of temperature. In the simulation of fire fighting process, water was sprayed on the specimens ablated at high temperature, and the sintered body of ceramic silicone rubber did not burst, showing good thermal shock resistance.

3. Halogen free, low smoke, low poison, self-extinguishing, environmental protection

Ceramic silicone rubber without adding halogen flame retardant can achieve flame retardant self-extinguishing effect, flame retardant UL94V-0, oxygen index can be as high as 38. In the flame ablation, the smoke will be completely cut off after a few minutes, in the following ablation process, there is no smoke itself. The combustion of ceramic silicone rubber produces carbon dioxide, water and silicon dioxide, which are non-toxic substances. Shrinkable Material Co.,Ltd., a kind of ceramic refractory silicone rubber produced by Shenzhen Woer Heat-Shrinkable Material Co.,Ltd., has been tested by National Fire Protection Building Materials Quality Supervision and Inspection Center, and the smoke toxicity is 25.0mg•L-1. The test animals did not die within 30min of exposure and 3 days after exposure, and the average body weight recovered. According to the national standard GB/T20285-2006 "Material Smoke toxicity Danger Classification" judgment, the material smoke toxicity reaches the quasi-safety level. Visible ceramic silicone rubber belongs to environmental protection materials.

4. Good electrical performance

The electrical properties of the optimized formulation of the ceramic silicone rubber are as follows: the volume resistivity before sintering is not less than 1015 ω ·cm. With the increase of sintering temperature, the volume resistivity decreases to 107 ω ·cm after burning at 1000℃ for 30min. The volume resistivity of ordinary silicone rubber before and after sintering is not less than 1015 and 107 ω ·cm, respectively.

5. Easy to processing

Rubber material preparation and product production process is similar to ordinary silicone rubber, using conventional rubber processing equipment (extruder, flat vulcanizing machine, injection machine, etc.) can be produced. The production process of refractory cable is simplified and the cost is reduced.

Ceramic silicone rubber formula analysis of the main components

1. The raw rubber

Mainly use methyl vinyl silicone rubber (such as domestic 110-2 silicone rubber). This kind of silicone rubber can be vulcanized with addition vulcanization system, vulcanization rubber tear strength is high, compression permanent deformation is low, suitable for fire-resistant silicone rubber sealing strip.

2. Reinforcing packing

The use of white carbon black, mainly gas phase white carbon black, also used precipitation white carbon black. Silica can improve the strength and hydrophobicity of silicone rubber vulcanizate after surface treatment. Surface treatment agents include silane coupling agent, octmethylcyclotetrasiloxane, etc.

3. Enhanced packing

Incremental filler only plays a very weak reinforcing effect on silicone rubber, and is generally used with silica black to adjust the hardness of silicone rubber vulcanized rubber, improve the technological performance of rubber material (such as extrusion performance) and reduce costs. Mainly quartz powder, diatomite, zinc oxide, titanium dioxide, talc and calcium carbonate. The quartz powder treated with silane coupling agent can not only improve the reinforcing property, but also play the role of sintering binder, contributing to the ceramicization.

4. Structural chemical control agents

In order to restrain the structuralization of silicone rubber reinforced with silica fume by gas phase method and ensure the processing performance, structural chemical control agents need to be added. Hydroxyl silicone oil (mass fraction of hydroxyl is 0.06~0.12) is generally used.

5. Heat stabilizer

The heat stabilizer generally uses selenium oxide, selenium hydroxide or selenium octanoate, iron oxide or iron octanoate