Silicone Modified Polyurethane Resin
Jul 20, 2023
Polyurethane is polymerized with diisobalate and polyol as basic raw materials. It has a development history of more than 60 years. It can be made into polyurethane foam, rubber, paint, Adhesive, Synthetic fiber, synthetic leather and other products. It is widely used in industry and daily life, and almost permeates all sectors of the national economy. Polyurethane has excellent properties such as good mechanical properties, wear resistance, oil resistance, cold resistance, tear resistance, chemical corrosion resistance, radiation resistance, good adhesion, elasticity, high gloss, and little change in soft and hard segments with temperature, as well as resistance to organic solvents. However, due to the fact that the molecular structure contains - NH - co - -, polyurethane has the disadvantages of poor temperature resistance, water resistance and wear resistance, which greatly limits the use of polyurethane materials.
Preparation of Silicone Modified Polyimide
Preparation of silicone modified polyimide by blending modification
The organic silicon components used for blending modification are usually modified. The polyimide (such as UltemlOO) is dissolved in an inert solvent (such as CHCb) and heated together with the modified silicone oil (the amount is not more than 30%) to obtain a polyimide silicone product with network structure. Its transparency, heat resistance, impact strength and moisture resistance are improved. GE Company of the United States blends Imide siloxane copolymer with cheese Imide to obtain an injectable resin with a glass transition temperature greater than 190 ° C; Compared with polyimide Imide, the product improves the oxygen resistant plasma properties and adhesive properties, and reduces the dielectric constant and moisture absorption. The company also blends carbonate siloxane block copolymer with polyimide, which has excellent mechanical properties and delamination resistance.
Polysiloxanes are a type of backbone with repetitive Si-0 bonds, with a bond energy of up to 422 2kJ/mol, siloxane has a large molecular volume, low cohesive energy density, and is a polymer directly connected to organic groups on silicon atoms. Silane monomers and polysiloxanes are commonly referred to as organic silicon, which has advantages such as low tenderness, good smoothness, low surface tension, good biocompatibility, good thermal stability, hydrophobicity, and wear resistance. Introducing organic silicon into polyurethane materials can improve their properties such as heat resistance, cold resistance, hydrophobicity, wear resistance, and good elasticity. The hard segment polyurethane and polymer chain segments keep the material at its original strength, greatly increasing the range of use of polyurethane materials. However, due to the significant difference in solubility parameters between polysiloxane and polyurethane, the results of simple blending and in-situ polymerization to prepare interpenetrating network polymers are not satisfactory. Therefore, copolymerization modification is one of the effective ways for organic silicon to modify polyurethane.
Physical Modification of Polyurethane
Polyurethane has good oil resistance and non polar solvent resistance, while organic silicon has good water and solvent resistance. Polyurethane can improve the oil resistance and non polar solvent resistance of organic silicon compounds, while organic silicon can improve the water and solvent resistance of polyurethane. Blending the two can complement each other's strengths. For example, one of the main ways for organosilicon to modify waterborne polyurethane is to blend amino siloxanes with polyurethane. Researchers found that the block copolymer of polydimethylsiloxane-b-polyethylene glycol had a good compatibilization effect on the polydimethylsiloxane/Polytetrahydrofuran polyurethane (PDMS/PU) blend system, and the mechanical properties were significantly improved. When polysiloxane was mixed with polyester polyurethane, there was phase separation phenomenon.
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