A new type of silicone rubber used cracking catalysts

Abstract: Analysis of the domestic waste silicone rubber used method of splitting the pros and cons, introduced a new type of catalytic cracking Jing BY-H. On the catalyst can be used effectively to improve the Central dimethyl siloxane mixture of recovery and quality of the average yield to the old rate of silicone rubber polysiloxane in more than 95% of the total; the recovery of dimethyl-Si-O ring Mixed homes, as EMBANKMENT-107 used in the production of refined silicon cavity port, and its viscosity up to 5O0 Pa 8, and stability; conditions have been significantly improved.

At present, the industrial production of silicone with the rapid development and the rapid growth of consumption. Need to recycle the waste materials of silicone rubber is also a significant increase; reasonable and effective to deal with all kinds of waste silicone rubber, silicone can not only reduce the cost of the product in environmental protection also played a positive role.

As has been used in silicone rubber vulcanization of silicone-organic molecules cross-linked density is not, and therefore may be appropriate catalytic cracking reaction. Will be one of the Si-O-Si chain depolymerization into dimethyl siloxane ring mixture [(R2SiO), = 3 ~ 10] (referred to as DMc); refined by the treatment again used in the production of a variety of silicone products. At present, there are a number of domestic manufacturers of silicone rubber used to engage in cracking DMc recovery of production, mainly in the following ways.

1 high-temperature pyrolysis method

Domestic manufacturers to adopt this technology very little, mainly due to smaller reactor, it is difficult to carry out mass production, high energy consumption, and very unsafe.

2 base catalysis

KOH is the recycling of used silicone rubber cracking DMC the most commonly used catalyst for a strong base. In the past, domestic manufacturers to adopt this technology more. Industrial production is also a long time. Although the technology used to be a higher quality of the DMC, the corrosion of equipment is also small, but the process following a number of problems: First, catalyst consumption, production and consumption lt crude DMC to be 700-750 kgKOH; Second, poor security, as Reactor with local prone overshooting, and thus lead to burning and explosion; Third, the scope of application of small, KOH used as a catalyst is only applicable to depolymerization button and type of scrap plastic mold. Does not apply to plastic glass.

3 acid catalysis

Acid catalysis in recent years, many domestic manufacturers are widely used by the process, a catalyst is used sulfuric acid. Using sulfuric acid catalytic cracking method used silicon glue rafter in the process, although at ease than the base catalysis, the production is also safer; but easy to plug the pipeline, product quality was not so satisfactory. The general process can be divided into catalytic concentrated sulfuric acid and sulfuric acid catalysis. Many small manufacturers have been using concentrated sulfuric acid catalysis, which is the biggest advantage of concentrated sulfuric acid used in the use of low cost and almost consumption, but because of severe corrosion of equipment, equipment replacement rate is high, as well as sulfuric acid waste to deal with difficult issues, The actual cost of production of integrated high; On the other hand, concentrated sulfuric acid catalysis DMC's recovery is also low, and very unstable. For good quality and content of the polysiloxane key categories of scrap, DMC, the average yield of only 40% to 45%; for a scrap with silicone rubber. The recovery rate of up to the maximum range of 15%.

Dilute sulfuric acid (50% to 85%) catalysis in recent years, many manufacturers are widely used by the process. Although the process has a high recovery rate of DMC, sulfuric acid and the repeated use of low-cost advantages, but it can not avoid serious corrosion of equipment, equipment replacement rate is high, as well as sulfuric acid waste to deal with difficult issues, and the use of technology, catalytic cracking of the cycle Extension of the one-pot reaction in about 10 h or more, the capacity utilization is also low.

BY-H catalyst

To further enhance the cleavage of an effective recovery of the DMC and product quality, we have made a cracking catalyst technology and its system and found a new type of catalytic cracking BY - H. The catalyst can be used effectively to improve the yield and quality of the DMC, with an average yield of silicone rubber used in polysiloxane total of more than 95%; recovery by the DMC as used in the production of refined 107 silicone rubber, the Viscosity of up to 500 Pa S, and good stability, and did not find the phenomenon of cross-linking; due to the mild reaction, no corrosion of equipment, do not plug the pipeline, the production process is safe; other. The catalyst for the preparation of simple to use and less able to recover many re-use, response time, the production too, in the process of decomposition can be applied to existing production facilities for all kinds of silicone rubber waste (including plastic buttons, plastic molds, glass Plastic) of the cracker.