Process for producing deposition white carbon black for silicon rubber

Abstract

The invention relates to a method for preparing silicone rubber by precipitating white carbon black. The method comprises the following steps: (1) raw materials: sodium silicate and dilute sulphuric acid; (2) reaction: firstly, the raw materials are stirred in a reaction kettle, is heated to a temperature between 80 and 90 DEG C; 15 to 20 percent of sulphuric acid is dripped to the reaction kettle within 30 to 45 minutes and the PH value of the sulphuric acid is between 9.5 and 11; secondly, an aqueous solution of the sodium silicate and 15 to 20 percent of the sulphuric acid are simultaneously dripped to the reaction kettle; the reaction time is between 45 and 55 minutes; the PH value is kept unchanged between 9.5 and 11; 15 to 20 percent of the sulphuric acid is continuously added into the reaction kettle within 20 to 35 minutes and is used to adjust the PH value to between 3.0 and 4.0; and a suspending solution is kept at the temperature and is aged for 30 to 60 minutes; (3) the suspending solution is filtered and washed; and (4) the suspending solution is dried to obtain a finished product. The method has the advantages that the produced white carbon black has even particles, good dispersion, and excellent processing performance and reinforcing performance in order that a silicone rubber product has good transparence and excellent anti-yellowing performance.

Description

technical field [0001] The invention relates to a preparation method of chemical products, namely a preparation method of precipitated white carbon black for silicone rubber. Background technique [0002] In the prior art, the mechanical properties of the silicone rubber itself are poor, and the tensile strength of the vulcanized rubber is less than 1 MPa, which has no practical application value. If silicone rubber is reinforced with white carbon black, its mechanical properties will be significantly improved and it will have a wide range of applications. Under normal circumstances, the raw materials for preparing precipitated white carbon black are sodium silicate and inorganic acids, mainly sulfuric acid, hydrochloric acid, and carbon dioxide gas. The price of raw materials is cheap and easy to obtain. The process route of this method is under alkaline conditions. Sodium silicate reacts with acid to produce product silica and by-product sodium salt. The suspension is fil...

AI Technical Summary

Problems solved by technology

The shortcoming of above-mentioned method is: reaction condition is not easy to control, and easily causes local reaction, produces silica gel, and the particle size of generation is uneven, and particle size distribution is wider, and dispersibility is poor, and reinforcing property is poor, often can't reach medium. Reinforcement requirements for high-grade silicone rubber can only be made of ordinary white carbon black

As a result, ordinary precipitated white carbon black is used as a filling and reinforcing agent for silicone rubber, and there are the following problems: 1. Poor processing performance, mainly manifested in the slow feeding of silicone rubber during mixing, poor dispersion, and difficulty in filtering the mixed rubber

2. The mechanical properties of vulcanized rubber are low

3. The transparency of the product is poor, and the yellowing is serious after the second-stage vulcanization