Basic details of silica gel raw materials
Silica gel is a kind of basic enzyme adsorption raw material, which belongs to amorphous compound. It contains dimethylsiloxane, dimethylsilicone oil, white carbon black (silica), coupling agent and filler. The main component is silica, and its chemical molecular formula is msio2 · nH2O. It does not dissolve strong electrolytes and all organic solutions, does not contain toxicity, colorless and tasteless, and has stable chemical properties. It does not react with all compounds except strong alkali and sulfuric acid. Various specifications and models of silica gel have different micro pore structures due to different production and processing methods. According to the analytical chemical composition and physical structure of silica gel, the management has decided that it has many characteristics that can not be replaced by other similar raw materials: high adsorption characteristics, good temperature resistance, stable chemical properties, high fracture toughness and so on.
Classification of silica gel: silica gel can be divided into hot rubber material type silicone rubber and room temperature rubber material type silicone rubber according to its rubber material characteristics. According to the different characteristics and scope of application, it can be divided into practicability, ultra-low temperature resistance type, ultra-high temperature resistance type, exquisite super strength type, corrosion resistance type and diagnosis and treatment type. According to the common individual differences, it can be divided into methyl poly methacrylic acid silicone rubber, methyl phenyl poly methacrylic acid silicone rubber, fluorosilicone, nitrile silicone rubber, etc.
1. In the whole process of mixing rubber, due to the low adhesion between the molecular formulas of silicone rubber, the white carbon black filler with high rib and high temperature resistance has become a more important harmony agent for silicone rubber. When selecting other coordination agents, Tong Yao must fully consider the requirements of high temperature resistance, that is, under the application specification of silicone rubber, they can not cause volatilization, melting, carburization or fading. In order to better maintain the heat resistance of silicone rubber, Reduce the cracking of silicon bond caused by acid and alkali attack. When mixing, it is necessary to prevent external acid and alkali from being brought in, and the acidic substances produced by the melting of chloroprene vulcanization accelerator must be removed immediately!
2. Put the raw rubber of the mixed rubber and other condiments into the vacuum kneader to boil. At the beginning, the temperature is not high. In the process of mixing, when the temperature height is slowly adjusted according to the friction to ensure 155-160 degrees, it can be more than half an hour.
3. Put the boiled glue into the internal mixer to polish and polish the whole bundle. This one only needs to pay attention not to get dirty. The number of rotations must be only 2-3 turns. 4. After polishing, cool it for about 3-4 hours. Then filter the glue according to the stainless steel filter screen in order to filter out some solid raw materials in the glue.
What are the types and advantages of white carbon black? There are two important types: gas chromatography analysis and ion exchange analysis: gas chromatography analysis: most of them are considered by silicon tetrachloride. After mixing with radon and O2 (vapor), at a high temperature of more than 1000 degrees, the harmful gas is first ignited with O2 and converted into water, and then reacted with silicon tetrachloride and converted into silicon powder through hydrolysis reaction. After being collected and deacidified by coalescer, white carbon black products are obtained. Advantages of gas chromatography analysis: pure absolute height, less SiOH, high rib rate, warm air rubber material, high picture quality of vulcanized rubber, good characteristics of electrical equipment, high quality of sealing, cushion resistance and dynamic fatigue elimination. Application scope of gas chromatography analysis: car parts, cables, cables, diagnosis and treatment, food industry, high wear-resistant, high full permeability silicone rubber products, resistant gaskets and sealing washers. Ion exchange: considering the chemical reaction rate of sodium metasilicate and hydrochloric acid or sulfuric acid under stirring, SiO2 accumulation can be obtained. White carbon black with particle size distribution can be obtained by filtering, drying and grinding. It can also be considered from alkaline earth metal magnesium oxide and obtained according to acid replacement reaction. Advantages of ion exchange: rubber materials have good resilience, swelling resistance and manufacturing characteristics, low price, plastic particles are not easy to structure, and are only useful for filling and rib in plastics and rubber and plastic products. Scope of application of ion exchange: general formed goods, printing cots, corrosion-resistant sealing gaskets and raw materials.
What's the difference between silicone and plastic? People usually mistakenly think that silica gel is a kind of plastic. In fact, this is wrong. The main components of raw materials of silica gel are extracted from silicon ore (such as dimethyl silicone oil and white carbon black), while the raw materials of plastics are extracted from epoxy resin glue. The cost of silica gel is more expensive than that of plastics and more eco-environmental protection.
