Organosilicon compounds, that contain Si-C key, and at least one organic moieties are attached directly to a silicon atom compounds, used often by those of oxygen, sulfur, nitrogen and the organic matrix and silicon atoms connected compounds as organosilicon compounds. Among them, the Si-O bond ( Si-0-Si ) as a skeleton composed of a polysiloxane organosilicon compounds, is the maximum number in the deepest, study, a class of the most widely used, the total amount of 90% above.
Silicone materials with unique structures:
( 1) the Si atom on the adequacy of the methyl polysiloxane backbone high energy shielding;
( 2) C-H non-polar, so that the forces between the molecules is very weak;
( 3) the Si-O key length is longer, Si-O-Si bond angle.
( 4) the Si-O key is a 50% ionic bond character of covalent bond (covalent has direction, ionic bond nondirectional ).
Silicone because of the unique structure, both the inorganic materials with the performance of organic materials, has low surface tension, viscosity temperature coefficient of small, high compressibility, permeability higher basic properties, and has high and low temperature resistance, electric insulation, resistance to oxidation stability, weather resistance, flame, water repellency, corrosion-resistant, non-toxic and tasteless as well as physiologically inert and other excellent properties, widely used in aerospace, electronics, construction, transportation, chemical, textile, food, light industry, medical and other industries, which is mainly applied to the seal, silicone adhesive, lubricant, coating, surface activity, release, defoaming, bubble, waterproof, moisture-proof, inert filler etc.. With the continuous growth of quantity and variety of silicone, applied domain widens ceaselessly, formed new chemical materials has become an independent school of important product system, many species are other chemicals can replace and essential.
Silicone materials according to their morphology is different, can be divided into: silane coupling agent ( organic silicon chemical reagents ), silicone ( silicone grease, silicone emulsion, silicone surfactant ), high-temperature vulcanized silicone rubber, liquid silicone rubber, silicone resin, composite materials.
Silicon rubber adhesive
Silicone rubber is a kind of linear high molecular weight silicone, molecular weight of 150000 or more generally, its structure form and the silicone oil is similar to. According to the silicon atom linked organic groups, silicone rubber with two methyl silicone rubber, methyl vinyl silicone rubber, silicone rubber, silicone rubber, silicone rubber, ethyl ethyl silicone rubber silicone rubber and many other varieties.
According to its different curing methods, silicone rubber can be divided into high temperature vulcanized ( HTV ) silicone rubber and RTV ( including room temperature vulcanized silicone rubber two categories ). Regardless of which type of silicone rubber, vulcanization is exothermic phenomenon. High temperature vulcanized silicone rubber is a high molecular weight silicone ( molecular weight is generally 40 to 800000), room temperature vulcanized silicone rubber is generally lower molecular weight ( 3 ~ 60000 ), the molecular chain ends ( sometimes also have among ) each with one or two functional groups, under certain conditions ( moisture in the air or appropriate catalyst ), these functional groups can react to form high molecular weight, the crosslinking structure. Room temperature vulcanized silicone rubber by vulcanization mechanism can be divided into condensation and addition type; according to its packaging method can be divided into two components and single component two types.
Silicon rubber composition having silicon-oxygen bond in the nature of the silicone rubber with natural rubber and other rubber do not have advantages, it has the most wide operating temperature range ( 100 ~ 350oC ), high and low temperature performance, in addition, also has excellent thermal stability, electrical insulation, weather resistance, ozone resistance sex, permeability, high transparency, tear strength, excellent heat dissipation and excellent adhesion, flowability and mold releasability, some special silicone rubber has excellent oil resistance, solvent resistance, radiation resistance and high temperature use properties. In the temperature range of use, silicone rubber can not only maintain certain softness, elasticity and surface hardness, mechanical properties have no obvious changes, and can resist long time thermal aging.
Because of special properties of silicone rubber for molding, high voltage insulator and other electronic components, so that the adhesive has excellent resistance to tracking, excellent mold releasability; used in the production of television sets, computers, copiers, has good thermal and insulating performance. It is also used as a requirement for the weatherability and durability of the molded gasket, electronic parts packaging materials, auto electrical parts for the protection of materials. Silicone rubber can be used for housing construction and repair, highway seam sealing and reservoir, bridge sealing. Silicone rubber can also be used for strong adhesion, weathering resistance, alkali resistance, resistance to water coating. Because the silicon rubber high temperature, in the auto parts production in large quantities. In addition, there are special uses of silicone rubber, such as conductive silicon rubber, silicone rubber, silicone rubber foam, molding silicon rubber, heat shrinkable silicone rubber.