Application of Organosilicon Modified Epoxy Resin

The ratio of polysiloxane to epoxy resin determines the performance of the resin. The high content of epoxy resin results in strong adhesion of the product, but its heat resistance is affected. Polysiloxane products with high twist content have obvious characteristics of high heat resistance and good electrical properties, but the adhesion and formability of the resin need to decrease. Therefore, it is necessary to find the optimal ratio of siloxane to epoxy in silicone epoxy resin through the following formula experiments.

The use of benzoic acid as a catalyst is beneficial for reducing the condensation temperature. The experimental results show that it is used in the reaction of silicone alcohol and epoxy resin, and can react at 160-180 ° C. A 500mL scale condensation of 10-126 can be completed. However, when the experimental scale was expanded to 3000mL, the condensation speed progressed very slowly, with a maximum time of up to 18h. This is because benzoic acid is insoluble in the input raw materials and toluene, and is prone to sublimation at l00 ° C. Therefore, benzoic acid is not an ideal catalyst.

The generation of organic silicone epoxy resin is mainly achieved through two condensation reactions: one is the dehydration reaction between the light group in the silicone alcohol and the light group in the epoxy resin, and the other is the reaction between the ethoxy group in the silicone alcohol and the light group in the epoxy resin.

According to relevant data, it is reported that polydimethylphenylethoxysilane and phenyltriethoxysilane react easily with epoxy resin at 170-18 ℃. Under specified conditions, ethanol remains the volatile substance of the reaction.

[Example l] In the mixed solvent of propylene glycol monopropionyl and xylene, add bisphenol A epoxy resin and Y-aminopropyltriethoxysilane to react for 3h at 60 ° C, add PhSi (partially hydrolyzed condensation polymer of 0Me origin and MeSiC OMe) 3 to the reaction mixture, continue to react for 3h at 60 ° C in water and isopropanol, and then add aluminum tripolyphosphate, y-epoxypropoxypropyl trimethoxysilane, dibutyltin dilaurate and pigments to the obtained resin, After being applied to steel sheets and air dried at room temperature for 7 days, the resulting coating showed good color even after being exposed to sunlight for 300 hours, stored outdoors for one year, or stored in a salt water test for 100 hours, with a light retention rate of 96%, demonstrating excellent corrosion and weather resistance. In addition, they also use the partially hydrolyzed polycondensate of Huliu propyl trimethoxysilane, PhSiCOMe) 3, MeSi (OM is adding BCOEt to propylene glycol monopropyl cheese and xylene, water and isopropanol) 3, react at 60 ° C for 3h, and then add epoxy resin, preservative, stabilizer, pigment, filler, etc. into the resulting product, which also has excellent corrosion resistance and weather resistance.

For example, by adding aminopropyltriethoxysilane and epoxy resin dropwise to MeOH and Si COEt) 4, the resulting product exhibits good adhesion, chemical resistance, scratch resistance, and water resistance after curing at ll0 ° C for 30 minutes. A coating made of epoxy modified silicone resin containing silica, tested in boiling water, does not crack for 90 days, and the coating is intact.
In addition, epoxy modified silicone resin can also be prepared by pre curing epoxy containing polysiloxane with epoxy resin, co condensation of ammonia containing polysiloxane with epoxy resin, and other methods.

[Example 2] The silicone modified epoxy resin used for heat-resistant and anti-corrosion coatings has a silicone content of 50%.

Operation method: Add xylene, cyclohexanone, and n-butanol in an appropriate amount to the resin melting pad with a jacket and reflux condenser. The condenser is filled with water, and the jacket is filled with steam. Start stirring and gradually raise the temperature to 70 ° C. Then, add the E-20 epoxy resin into the pad in batches and melt it. Finally, raise the temperature to 90 ° C and keep it warm. After it is completely melted, stop heating and cool it to 30-40 ° C before filtering, loading, and standby.

Add epoxy resin solution and organosilicon oligomer solution to the resin reaction system equipped with stirring, thermometer, reflux condenser, and oil-water separator. React at 180~190 ° C under stirring. Ethanol precipitates during the reaction. Take samples and measure the gelation time on a 200 ° C electric heating gelation plate. If the gelation time reaches 3-5 seconds, it is the reaction endpoint. Stop heating, cool to below 120 ° C, then add xylene to dilute, stir evenly, filter and barrel when it drops to 30-40 ° C for backup. The solid content of this modified resin solution is 50%.

Experiments have shown that in the reaction between organosilicon oligomers (polyphenylmethylethoxysiloxane) and epoxy resin modification, only the light groups in the epoxy resin participate in the reaction, and the number of epoxy groups in the epoxy resin remains basically unchanged. Therefore, this modified resin solution can be cured into a film using amino resin as a crosslinking agent at high temperatures (200 ° C), or polyvinylamine or low molecular weight polyamide as a crosslinking agent at room temperature.

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