1.Brief intruduction of chlorinated natural rubber
Chlorinated natural rubber (CNR) is chlorinated polymer from reaction of natural rubber and chlorine. The appearance of chlorinated natural rubber industrial grade is white or pale-yellow powder. It is non-toxic and tasteless, chlorine content is 63-65%. The average molecular weight is between 5000-10000, it is dissolved easily in aromatic hydrocarbons, halohydrocarbon, ethers, esters, petroleum solvents, ketones (acetone excluded) and other organic solvents, is miscible with alkyd resins, epoxy resins, phenolic resins, polyurethane and other synthetic resin, is not dissolved in aliphatic hydrocarbons, aliphatic alcohols and water.
2. General advantages of chlorinated natural rubber
Since there are large amount of chlorine atoms on the cyclic structure of C-C main chain, CNR has many excellent properties and applications as follows:
a) Without double bonds and other active radicals on saturated molecular chain structure, chlorinated natural rubber is chemically stable. With excellent corrosion resistance, Chlorinated natural rubber resists corrosion from acid, salt, chlorine, H2S,SO2 and other corrosive chemicals.
b) Since Cl- radical has anti-mold and flame retardant properties, the products have anti-mold and flame retardant properties too.
c) Since C-Cl bond is strongly polar bond, it gives good adhesion to the surface of steel, aluminum, cement and timber and other materials.
d) With the C-C main chain in its chemical structure, CNR is modified rubber, that is why it can be well compatible with natural rubber, neoprene, nitrile rubber and other kinds of rubber
e) With the cyclic molecular structure, the Chlorinated natural rubber has better properties of adhesion, flame resistance, oil resistance and elastic modulus.
f) With good heat resistance, only a micro amount of chlorinated natural rubber decomposes at 125C and it does not soften and burn over 200C
CNR is divided into different types on the basis of different viscosity, which are applied in different areas. See Table 1 below (The CNR types shown in table 1 is classified by the ICI, British, 20% toluene solution).
With the increasing of molecular weight of Chlorinated natural rubber, the properties of viscosity, product durability and gloss-maintenance improves, while the properties of good dispersibility, brushability, sprayability, compatibility and solvent dilution declines. The CNR products with high viscosity of 30mPa.s Min is called High Viscosity Chlorinated Natural Rubber (HVCNR) and mainly applied in brushing paint, adhesive, paper or textile coating, rubber products (to improve the tire performance).
When being applied in coating production, CNR can be used with multi nature or synthesis resin and rubber with a broad adjustable range and the hardness and wear resistance of the products can be improved in most cases.
Table 1 Application of Chlorinated Natural Rubber
|R-5||4-7||Thick paste printing ink|
|R-10||8-13||Spray Paint ,anticorrosive Paint, Marine Coating, Traffic Paint¡¢Architectural Coating|
|R-20||16-24||spray paint, anticorrosive paint, Marine Coating, Traffic Paint¡¢Architectural Coating|
|R-90||75-120||Brush coating,Adhersive,rubber products|
|R-125||120-180||Brush coating,Adheresive,rubber products,paper coating, fabric coating|
|R-300||200-300||Adheresive,rubber products,paper coating, fabric coating,Tyre|
Note : Viscosity is tested at 25C, 20% toluene solution.
Being applied in adhesive industry, the HVCNR can be used as base material or as auxiliary material of adhesive. When HVCNR is applied as base material, the adhesiveness property of the products can be greatly enhanced by adding halogenated polyolefins, aromatic nitroso compound or isocyanate.
When HVCNR is used as auxiliary material, such as in producing chloroprene rubber, nitrile rubber and polyurethane adhesives, it is generally used as a modifier additive to increase the cohesive strength and adhesion strength of adhesive film, improve high temperature durability and resistance to various chemicals of bonding joints, enhance anti-gel properties, and therefore significantly improve performance of the products, giving the products greater versatility.
Ruize Chemical Co., Ltd (http://www.rzhg.cn) is the sole legal producer of solvent process CNR production in China. With many years of production experience, and long-term commitment to the progress of CNR production technology, the company is in cooperation with the Beijing University of Chemical Technology. After many years of experiments and exploration of the using advanced technology in the solvent viscosity control techniques, Ruize is the first company solves the commercial production problems of the high viscosity chlorinated natural rubber products in China, with the products achieving internationally accepted standard.
At present, our company can produce a series of chlorinated natural rubber with a variety of viscosities ranging from 30-300 mPa.s.