Natural rubber (NR) varieties and grading standards

Natural rubber is mainly classified according to the method of manufacture. In each category, it is graded according to the level of quality or raw materials.

The classification of natural rubber is as follows:

Rubber from Hevea Rubber - - 1. General Purpose - (1) Granules
(2) Smoke Tablets
(3) Air dried glue
(4) Silicone rubber
2. Special Types ---- (1) Constant Viscosity Rubber, Oil Filled Rubber
(2) Low-viscosity rubber, rubber clear rubber
(3) Easy-to-use rubber, carbon black
(4) Purified rubber, clay co-deposited
(5) Tire rubber, loose rubber

3. Modified Classes----(1) Hard Crystallized Rubber, Epoxidized Rubber, Chlorinated Rubber (2) Grafted Rubber, Liquid Rubber, Hydrochlorinated Rubber
(3) Cyclized rubber, thermoplastic rubber

Other plant-produced rubber----1. silver chrysanthemum rubber
2. Eucommia rubber

General-purpose natural rubber has two classification methods: one is the classification according to the quality of appearance, such as smoke tablet adhesive and tablet rubber are graded according to this method; the other is classified by physical and chemical indicators, this method is more scientific, generally granular rubber It is graded according to this method.

Smoke tablet rubber has more than 80 years of production history. With the appearance quality classification, China's national standards are divided into one, two, three, four, and five levels. The highest level of quality, after a gradual decline in quality. For example, the requirements and the film are free of mildew, no oxidation spots, no smoke, no smoke, no smoke, no opacity. The secondary smoke film adhesive allows the film to have a small amount of mildew, slight rust, no oxidized spots and smoked impermeability. All levels of smoke tablets have standard glue samples for reference. Smoke tablet rubber packaging is relatively large, inconvenient to use, the international provisions of the package weight of 102 ~ 114kg, a volume of 0.14 cubic meters, the plastic bag on the smoke plastic film, grade, factory name, production date and other signs.

Due to the different raw materials and manufacturing methods, the sepals can be divided into two kinds: latex sepals and hybrid sepals. The quality of each medium view is also divided into different levels.

Standard rubber or granular rubber is a new type of natural rubber developed in the 1960s. In the past, conventional products such as smoke tablets, sepals, and air-dried tablets were tied to the development of natural rubber regardless of the classification method or manufacturing method. Therefore, Malaysia began to implement the standard rubber program in 1965, and developed the production of granular rubber on the basis of the grading of physical and chemical properties of raw rubber. Standard rubber refers to rubber classified according to physical and chemical properties such as mechanical impurities, plastic retention, initial plasticity, nitrogen content, gray content, ash content, and color index. The standard rubber packaging is also relatively advanced, and it is generally packaged in polyethylene film and has a distinctive logo. The package has a small weight and is easy to move. The weight of packaging in Malaysia is 33.3kg, and that in China is 40kg.

The classification of standard glue is more scientific, so this classification method was quickly accepted by major natural rubber producing countries and international standardization organizations, and has successively established standards for standard glue. These standards are roughly the same, but they are not exactly the same. For example, the ISO 2000 regulations are divided into five levels. The national standard GB8081-87 provides four levels.

The above mentioned are the natural rubbers that are passed through the varieties. They are used in large amounts and have a wide application area. Before the standard glue did not appear, the amount of smoke glue was the largest. At present, the amount of standard glue is the largest.

Other special rubber and modified natural rubber, such as constant viscosity rubber, low viscosity rubber, easy-to-operate rubber, purified rubber, tire rubber, rubber clear rubber, hard crystalline rubber, carbon black co-sinking rubber, clay co-sinking rubber, grafting Natural rubber, epoxidized natural rubber, cyclized natural rubber, etc., have their own special properties and uses, but they use less.