Yesterday, Shandong monomer factory continued to decline at an average rate of 200 yuan / ton, and the DMC quotation fell to 20200 yuan / ton. Other monomer factories remained stable, but the overall market was light, and everyone could not place an order. Therefore, in this relatively idle stage, let's put down the market for the time being, and only learn, which is worth talking about. Today, let's talk about a niche product: polymer raw rubber.


There are four kinds of downstream products in the silicone industry: silicone oil, silicone rubber, silicone resin and silane coupling agent. There are not a few products in each major category. In silicone rubber, there is a kind of small but indispensable existence, which is high molecular weight methyl vinyl silicone rubber, referred to as polymer raw rubber.


Definition of polymer raw rubber


High molecular weight raw rubber is different from conventional molecular weight raw rubber. Conventional molecular weight raw rubber refers to the molecular weight of 500000-600000, which generally contains vinyl and is commonly used in the production of rubber blends. Polymer raw rubber generally refers to raw rubber with a molecular weight of more than 800000.


Manufacturer of polymer raw rubber

At present, the large-scale production plants of polymer raw rubber, which are sold as the main products of the factory, include Nanjing dongjue, Yichang Xingyue and Dongguan New Oriental. Monomer factories also produce a small amount, but generally do not form the main product sales.


Main quality indexes of polymer raw rubber

In addition to meeting the basic sensory indicators such as transparency and odourless, the main quality indicators of polymer raw rubber include molecular weight, volatile matter and vinyl content.


01
molecular weight

The calibration molecular weight deviation is generally ± 20000. For example, the calibration molecular weight of a batch is 900000. Due to detection errors and other factors, it belongs to the normal deviation range in the range of 880000-920000. At present, the molecular weight of polymer raw rubber produced in batch in China is generally no more than 1.2 million.


02


Volatile matter

The national standard requires that the volatile content of common molecular weight raw rubber is ≤ 2%. The requirement for volatile matter of polymer raw rubber is ≤ 1%. If the volatile is too high, the direct sense is that the raw rubber has a peculiar smell.


03

Vinyl content

According to the different application fields, the vinyl content of polymer raw rubber can be roughly divided into zero vinyl raw rubber (commonly known as nail seal raw rubber) and low vinyl raw rubber (vinyl generally does not exceed 0.04%).

Main application fields of polymer raw rubber

There are four main application fields: silicone curing agent, plastic modification, special rubber compounds and textile additive

01
Silicone vulcanizing agent

Polymer raw rubber is an important raw material of silicone vulcanizing agent, which mainly plays a role of carrier in products. The high molecular weight used in silicone vulcanizing agent industry ranges from 800000 to 120000, but they all need to meet the requirements of zero vinyl content. The effective components of silica gel vulcanizing agent, such as double 24 and double 25, are liquid. If they are directly added, it is difficult to control the dosage. At the same time, because double 24 and double 25 are dangerous goods, there will be great safety hazards in transportation and storage, so the development of silica gel vulcanizing agent has experienced the process from liquid to powder and then to paste. Liquid refers to the direct addition of liquid peroxide, powder refers to the mixing of peroxide and silica, and paste refers to the mixing of peroxide and polymer raw rubber.


02

Plastic modification

As a raw material for plastic modification, raw rubber mainly uses the characteristics of smooth and weather resistant silicone. In the plastic modification industry, both zero vinyl and low vinyl of polymer raw rubber are used. At present, the largest application field is shoe materials and cables. In Fujian, where shoe material processing is relatively concentrated, the monthly demand for high molecular weight raw rubber is 300 tons. However, because the price of raw rubber with molecular weight of more than 800000 is about 1500 yuan / ton higher than that of ordinary molecular weight, many processing plants will retreat to use raw rubber with molecular weight of more than 700000. This will have an advantage in cost. For the cable industry, due to the high quality requirements and the stability of raw materials, once the raw materials are fixed, they will not be easily changed, which is mostly the case in the silicone masterbatch factories in the Pearl River Delta.


03

Special compound

It is mainly the production plant of ceramic silicone rubber. In a broad sense, ceramic silicone rubber also belongs to the category of compound rubber. In this industry, raw rubber with low vinyl content is generally used. After the ceramic silicone rubber is processed into cable material, it can withstand high temperature. Even after a fire, the cable with ceramic silicone rubber as raw material will maintain a certain hardness and continue to be energized for a certain period of time to reduce the loss caused by the fire. Another big application is the silicone wire of small household appliances, which is used in the innermost layer and the outer conductive material to improve the puncture resistance of the wire.


04

Textile auxiliaries

In textile auxiliaries, many silicone products will be used. High polymer raw rubber is mainly used in textile auxiliaries as thread oil, which is used as raw material to adjust the viscosity of thread oil and improve the smoothness. There are also raw polymer rubbers as raw materials for lotion processing, but they account for a small proportion.


05

Cost and price of high molecular weight raw rubber

The main raw material of high molecular weight raw rubber is still DMC, but different from the DMC used by ordinary molecular weight raw rubber, high molecular weight raw rubber has higher requirements for D4 content in DMC, which leads to the relatively narrow supply of raw materials in high molecular weight raw rubber production plants. At present, only half of the more than ten monomer factories can provide DMC that can fully meet the production of polymer raw rubber. In addition to DMC, it is the capping agent that controls the molecular weight. Tetramethylammonium hydroxide is generally used in China. The amount of addition plays a decisive role in the control of the molecular weight of raw rubber. If the raw rubber containing vinyl is produced, the raw material also has vinyl ring. These three main raw materials have the same molecular weight as ordinary raw rubber, but due to the poor fluidity of polymer raw rubber, the processing efficiency is relatively low. Generally speaking, the price of polymer raw rubber is about 1500 yuan / ton higher than ordinary molecular weight raw rubber. When the supply is relatively tight, the gap will be larger.