Rubber divided by source: wild rubber cultivation, rubber grass rubber, gutta percha. In accordance with the process can be divided into: smoked sheet rubber, standard rubber, crepe rubber and latex.
(1) Smoked Sheet (RSS): divided 1,2,3,4,5 plus premium. Smoked Sheet is packed into the film, the color is yellow, the best is golden yellow. It can be judged by visually color index level.
Technology: 35% of latex diluted impurity filter → → → water → defoaming acid solidification in addition to water → → → tabletting smoked and dried. Because latex coagulation time is three hours or so, so the production of tobacco sheet prior to solidification processing latex. And there is no such requirement in the standard plastic production.
No. 3 tobacco piece rubber bales to the original packaging, heavy pieces of 111.11kg, 9 ton bag.
The main producing countries: Thailand, India, (RSS3, RSS4 poor quality smoked sheet in India, generally used for adhesive production.) Indonesian tobacco sheet (Indonesia's state-owned farms that produce only very small amount. ).
Main uses: tire factory (radial: Because of cost reasons, rarely use tobacco sheet production radial tire), bias tires and engineering tires giant tire), cable plant, belt conveyor plant.
(2) standard plastic:
Classification is in accordance with standard rubber impurities, the initial value of plasticity, plasticity retention rate, nitrogen content, volatile matter content, ash content, color index. The main classification is 5L, 5,10,20,50, wherein the content of impurities leading indicators, the current international market, the main producing countries of standard plastic is 20 standard. Vietnam also produced 3L. Is a standard plastic. Wherein 3L, 5L color is yellow. The remaining colors are dark.
Standard rubber production process: a mechanical method, the diluted latex → filter → → → acid coagulation dehydration → drying.
Chemical methods: adding coagulant latex → → → drying centrifuge.
Standard plastic is divided into: plastic particles and plastic extrusion. Plastic extrusion process just one more in the pulverization process.
China's major imports are plastic particles, mainly China's tire production process requirements, foreign multi-purpose plastic extrusion process.
The main producing countries: Malaysia, Thailand, Indonesia, Vietnam, China, India.
Main uses: tire plant.
Price trends: SMR, STR, SIR, SVR.
(3) crepe rubber. Generally divided into white and brown crepe crepe. Mainly plastic garbage produced, such as clay, micelles.
(4) Latex: latex → plus amine centrifuged together. Divided into high and low amine amine latex emulsion. Latex is a liquid, volatile, usually bottled and packaging space suit. Slightly higher than the price for a barrel of space filled.
Latex production process will produce skim rubber, its price is 50% -60% more points with the shoe.
The main producing countries: Thailand, Vietnam, China.
Main purpose: glove factory, family planning supplies, shoe.
Quality standards of natural rubber
According to the shape of natural rubber can be divided into two categories: solid natural rubber (film and plastic particles) and concentrated latex. In everyday use, solid natural rubber accounted for the majority proportion.
Film according to different manufacturing process and shape, divided into smoked sheet and air-dried film, white crepe, brown crepe and so on. Smoked sheet natural rubber is the most representative species, was once the largest amount, the most widely used types of plastic a smoke film generally graded according to shape, divided into premium, one, two, three, four , five, a total of six, less than five are categorized as substandard glue.
Plastic particles (ie standard rubber SMR, also known as technical grade rubber TSR) is based on the international unity of the physical and chemical performance, graded index, which includes physical and chemical properties of impurities, the initial value of plasticity, plasticity retention rate, nitrogen content, volatile content , ash content and color index, of which the impurity content oriented indicators. According to the national standard GB / T8081-2008, technical grade rubber (TSR) classification should be based on TSR TSR performance and production of raw materials used may be.
The main physical properties of natural rubber
Natural rubber raw rubber glass transition temperature of -72 ℃, plastic flow temperature 130 ℃, beginning decomposition temperature of 200 ℃, intense decomposition temperature of 270 ℃. When natural rubber vulcanization, its Tg rise, it would not happen again viscous flow.
Elasticity of natural rubber: its raw rubber and a crosslinking density is not too high elastic vulcanized rubber is high. For example, in the range of 0-100 ℃, resilience between 50-85 ℃, the elastic modulus of only 1/3000 of steel, elongation up to 1000% to 350% stretch, after retracting permanent only 15% of the deformation, the higher elasticity of natural rubber, butadiene rubber after general purpose rubbers.
The strength of natural rubber: elastic material, natural rubber, raw rubber, rubber, vulcanized rubber are high intensity. Unvulcanized rubber tensile strength called green strength, green strength of natural rubber up to 1.4 ~ 2.5Mpa, suitable green strength is necessary for the rubber molding process. Natural rubber has high tear strength, up to 98kN / m, and its durability is better. Reasons for the high mechanical strength of natural rubber is that it is self-reinforcing rubber when the tensile stress causes the macromolecular chains along the direction of orientation crystallization.
The electrical properties of natural rubber: natural rubber material is non-polar, is a good insulating material. When natural rubber vulcanization, by the introduction of polar factors, such as sulfur, accelerators, etc., so that the insulation performance.
Medium resistance of natural rubber: natural rubber is a non-polar material, it is soluble in non-polar solvents and non-polar oils. Natural rubber impatience cyclohexane, gasoline, benzene and other media, uncured rubber can be dissolved in the medium, the vulcanized rubber is swelling. Natural rubber is not soluble in polar acetone, ethanol, but insoluble in water, resistant to 10% hydrofluoric acid, 20% hydrochloric acid, 30% sulfuric acid, 50% sodium hydroxide and the like.
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