Organosilicon Compounds to Prepare Polyurethane

Silanol hydroxy terminated siloxane modification method Silanol refers to a siloxane compound with a light group directly connected to a silicon atom. The light group has certain activity and can react with an NCO to obtain modification. Due to poor compatibility between the two, solvents are usually used during the reaction process. The final form is the Si-0-C bond, which has poor hydrolysis resistance and is unstable. A new type of polyurethane was synthesized with polymethyl diphenyl isophorate, polyethylene glycol CPMDI, PEG), PDMS poly Dimethylsilane (DEG diethylene glycol) containing silanol hydroxyl as raw materials, Due to the formation of flame-retardant silica on the surface of the modified material, which prevents further oxidation and combustion inside the material, the thermal weight loss rate of the material is low, and the formation of silica on the surface significantly reduces the thermal conductivity of the material compared to before modification. High solid content silicone modified polyurethane was synthesized from polycarbonate polyol (PCD), polybutylene glycol Adipic acid polyol hydroxyl silicone oil (DHPDMS), Isophorone diisoazoate (IPDI) and dimethylol propionic acid (DM) ­ The larger the molecule of PDMS, the stronger its hydrophobicity, the smaller its water absorption, and the smaller its fracture resistance.
Examining the effect of organic silicon content on the resin, it was found that the water and heat resistance properties were improved, but the resin had a rough surface with microphase separation. Modified waterborne polyurethane with high organic silicon content (48%) was obtained using direct hydroxyl terminated organic silicon as the raw material using a two-step method. The optimal reaction temperature was determined. The study found that as the silicon content increased, it migrated to the surface to wrap the polyurethane and had a hydrophobic effect, improving mechanical properties and aging resistance. However, excessive content caused a sharp increase in viscosity and a decrease in hardness due to severe phase separation. Research on this type of silanol hydroxy modified polysiloxane has found that although polyurethane materials with high silicon content can be obtained, the S corpse (} -- C bond formed by the reaction of - OH and - NCO of hydroxy terminated polydimethylsiloxane is easily hydrolyzed, and the resulting compound is unstable in aqueous solution. Therefore, this modification method is limited in its application.