Preparation of MQ Silicone Resin
Apr 7, 2023
MQ resin is a type of organic silicon polymer compound with bright prospects and significant industrial application value. Firstly, it can be mass-produced from cheap water glass, rather than expensive raw materials such as organosilicon metal compounds and silicon; Secondly, unlike other organosilicon resins, it does not require strict control of the raw material ratio during the preparation process; Once again, it is easy to modify and has broad application prospects. The preparation methods of MQ resin are mainly divided into two methods based on the source of Q chain raw materials: orthosilicate ethylene glycol method and sodium silicate (water glass) method. The sodium silicate method can also be subdivided into three types: silicic acid method, silica sol method, and colloidal silica method.
(1) TEOS method uses TEOS as the Q group as the raw material, and the product structure is relatively clear, which has been extensively studied and used. First, burn hexamethyldisiloxy under acidic conditions for hydrolysis, then drop it into ethyl orthosilicate at 70℃ for hydrolysis and condensation, and finally wash and purify it with water. The molecular weight distribution of its product is narrow, but washing is complex and costly. This method can control the molecular configuration of the resin by controlling the proportion of raw materials.
In order to optimize the production process, research has been conducted on n (M)/n (Q), solvent, water dosage, acid concentration, and reflux temperature. John et al. discussed the influence of solvent type and water dosage, and believed that the selection range of solvents is relatively wide, with the optimal dosage being 0 25-2 times. In order to facilitate separation, solvents that are easily mixed with water, such as alcohol, ketone, cheese, etc., should be avoided as much as possible; In order to avoid gel and extend the storage time of products, toluene, xylene, etc. should be selected as the solvent. The appropriate amount of water is 2-40 times the total amount of TEOS and capping agent.
(2) At present, the sodium silicate method is mainly used as the raw material for the production of MQ silicone resin both domestically and internationally. Although the resulting product has good performance, its high price limits its application to some extent.
The silicic acid method uses water glass as the four functional group organic silicon unit as the Q group as the raw material, and hexamethyldisiloxane (MM) or trimethylmonochlorosilane (Me centered Cl) as the single functional group organic silicon unit as the M group. Under low temperature and acidic conditions, hydrolysis and condensation occur to form a low molecular weight silicone resin. Then, water washing, separation, and purification are carried out to prepare MQ silicone resin, which has similar properties to the products prepared by the orthosilicate method. Among them, MM is the end capping agent and the molecular weight of MQ silicone resin, while the self condensation product after hydrolysis of water glass constitutes the basic component of MQ silicone resin.
(3) Comparison between orthosilicate acetic acid method and water glass method
The organic water glass method and the ethyl orthosilicate method each have their own characteristics. In terms of the maturity of the synthesis process, the water glass organic synthesis method has been studied more widely due to its simple process, relatively cheap raw materials, and easy availability; In terms of production efficiency of synthesis, the ethyl orthosilicate method is better. From the comparison of the products obtained by the orthosilicate method and the water glass method shown in Table 2-10, it can be seen that the solubility of the products obtained by the orthosilicate method is not as good as that by the water glass method. This may be because orthosilicate is a monomer with a purity of over 98%, and the local concentration in the reaction system is high, which is prone to excessive self aggregation and gelation. The average yield of water glass method is low, which may be due to the fact that the mass fraction of water glass is usually less than 10% to prevent gelation, and it is easy to prepare low MQ products (when M/Q<O. 5, it is easy to gel). In addition, the molecular weight distribution of the products obtained by the orthosilicate method is relatively narrow.
Silibase Silicone Resin series products have these properties: high temperature resistance, good electrical insulation, resistant to moisture waterproof, fire retardant, anti-corrosion and so on.Our products are Methyl Silicone Resin Intermediate，Methyl MQ Silicone Resin Powder，MQ Methyl Silicone Resin Liquid，MQ Silicone Resin，MQ Silicone Resin Powder，Liquid MQ Silicone Resin，Vinyl MQ Silicone Resin.
