Views: 0 Author: Site Editor Publish Time: 2016-07-09 Origin: Site
Rubber production technology brief
First, the basic process
Rubber variety, but the production process, but basically the same. In general solid rubber (gum) as raw materials The basic process of rubber products include: mastication, mixing, rolling, extrusion, molding, curing six basic steps. Of course, raw materials preparation, product finishing, testing and packaging basic process ultimately. Machining process is a process to solve the main rubber elastic and plastic properties of this conflict through a variety of technical means, so that the elastic rubber Plastic compounds have become plastic, and then add a variety of ingredients is made semi-finished products, and then vulcanized semi-finished plastic and has become highly elastic, good physical and mechanical properties of rubber products.
Second, the preparation of raw materials:
1. The main raw material for rubber products are rubber as the basic raw material, but raw rubber is grown in tropical and sub-tropical rubber trees collected from manually cut the bark.
2. The various compounding agents: in order to improve certain properties of rubber products and auxiliary materials added. 3. The fiber material (cotton, linen, wool and a variety of man-made fibers, synthetic fibers) and metal materials (steel, copper) as a reinforcing material of rubber products, in order to enhance the mechanical strength, limiting product variants. In the raw material preparation process, the ingredients must be accurate in accordance with Formulation. In order to make raw rubber and compounding ingredients can be uniformly mixed with each other, the need for materials processing:
To bake raw rubber soft 60--70 ℃ in the drying room, then cut plastic, gel breaking into small pieces; ingredients are: massive, such as paraffin wax, stearic acid, rosin to smash;
If mechanical impurities or contain coarse-grained to be screened powder was removed;
Liquid, such as (pine tar, coumarone) requires heating, melting, evaporation of water, filtered miscellaneous
Complexing agent to be dried, or easy to agglomerate, if not uniformly dispersed when mixing, bubbles during vulcanization, it will affect the quality of products;
Raw rubber elasticity, the absence of the necessary processing plasticity performance, it is not easy to process. In order to increase its plasticity, so to raw rubber mastication; Thus, while it is easy kneading ingredients uniformly dispersed in raw rubber; Meanwhile, calendering, molding process also helps to improve the rubber penetration (penetration fiber fabric inside) and forming mobility.
The long-chain molecules gum degradation, a process called plasticity formation mastication.
Raw rubber mastication method of mechanical mastication and mixing two kinds of thermoplastic. Mechanical mastication is not too high in temperature by the action of mechanical compression and friction mastication machine, so that degradation of long-chain rubber molecules shortened by highly elastic state to a plastic state. Thermoplastic raw rubber mixing is to pass into the hot air, under the action of heat and oxygen, so that the degradation of long-chain molecules becomes short, thereby obtaining plasticity.
In order to adapt to different conditions, access to a variety of performance, but also to improve the performance of rubber products and reduce costs, it must add different ingredients in the raw rubber.
Kneading is to mastication after the complexing agent is mixed with raw rubber, rubber mixing machine on by mechanical mixing action to make ingredients fully uniformly dispersed in raw rubber in one process.
Kneaded rubber production is an important step in the process, if uneven mixing, it can not give full play to the role of rubber and compounding agents, impact product performance. After kneading the resulting compound, known as the rubber, it is manufacturing various rubber products, semi-finished materials, commonly known as plastic materials, are usually sold as a commodity, buyers can take advantage of direct molding compound, which is made vulcanization We need rubber products. Depending on the recipe, mix a range of different properties of different brands and varieties of choices. Fifth, molding
In the rubber production process, using a calender or extruder wide range of pre-formed shape, the size of each different process, called molding. Molding methods are: 1. calendering:
For the manufacture of a simple sheet, plate products. It is the mix through a calender pressing into a certain shape, a certain size film forming method called rolling.
Some rubber products (such as tires, tape, rubber hose, etc.) of textile fiber material, must be coated with a thin layer of glue (glue on the fiber, also called gum paste or eraser), coating processes are generally completed on the calender. Fibrous material before rolling the need for drying and gumming, drying purpose is to reduce the water content of the fibrous material (to avoid evaporation of water bubbling) and raising the temperature of the fiber material in order to ensure the quality of the rolling process. Dipping step is necessary before hanging plastic, the purpose is to improve the bonding properties of the fiber material and rubber compounds. 2. extrusion molding:
For more complex rubber products, such as tire tread, hose, wire, plastic coated surface need the extrusion molding method of manufacture. It is to mix a certain plasticity, and placed into the hopper of the extruder, extruded at a screw, through a variety of mouth (also called a model) is a method of continuously molding. Before extrusion, plastic materials should be preheated to make rubber soft and easy extrusion to obtain a smooth surface, accurate dimensions of rubber products.
Molding method can also be used to manufacture certain complex shapes (such as cups, seals) rubber products, with the forming of the male and female mold, the plastic material is placed in a mold thermoforming. Sixth, vulcanized
The plastic rubber into an elastic rubber vulcanization process is called, it is a certain amount of vulcanizing agent (such as sulfur, vulcanization accelerators, etc.) was added to the semi-finished products made of raw rubber (vulcanization carried out in the tank), the provisions of temperature heating, insulation, making raw rubber between linear molecules generated by "sulfur bridges" and cross-linked network structure established body, so that the plastic material into a vulcanized rubber having high elasticity. Due to the crosslinks is mainly composed of sulfur, so called "cure." With the rapid development of synthetic rubber, a vulcanizing agent and now a lot of variety,
3 in addition to sulfur, there are organic polysulfide, peroxides, metal oxides and the like. Therefore, those who make the plastic rubber-like structure, the elastic rubber into three-dimensional network structure of the process called vulcanization, who can play a "bridge" role in the rubber material substances are referred to as "curing agent."
Elastic rubber vulcanized called vulcanized rubber, also known as soft rubber, commonly known as "rubber."
Is one of the most important vulcanization process of rubber processing, rubber products must be cured to achieve the desired performance. Uncured rubber, it is in the use of no value, but less sulfur (vulcanization degree is not enough, the curing time was not able to achieve the best condition) and persulfate (curing time exceeds significantly decreased performance) are rubber performance degradation. Therefore, the production process must be strictly controlled curing time to ensure that the vulcanized rubber has the best performance and longest life. VII auxiliary measures
In order to achieve performance, support measures should be added in the production process: 1. Increase strength - with a hard carbon black, mixed with phenolic resin; 2. increase the wear resistance - is equipped with a hard carbon black;
3. tightness demanding - less highly volatile components; 4. Increase heat resistance - the introduction of new curing process;
5. Increase the cold - by solving the gum sticks mosaic, reduced crystallization tendency, the use of low temperature plasticizers; 6. Increase the flame resistance - not flammable chemicals, less softener, use of flame retardants ( such as: antimony trioxide); 7. increase resistance to oxygen, ozone resistance - use of diamine protectant;
8. improve electrical insulation - with high filler structure or metal powders, equipped with antistatic agents; 9. improve the magnetic properties - the use of strontium ferrite powder, aluminum, nickel and iron, barium iron powder as filler;
10. improving the water resistance - the use of lead oxide or resin curing system, equipped with a low water absorption fillers (such as barium sulfate, clay);
11. improve oil resistance - fully crosslinked, less plasticizer; 12. improve the degree of acid - multi-purpose filler;
13. The increase of high vacuum - is equipped with a less volatile additives; 14. reduce the hardness - lots of filling softener. Eight, rubber products category
Rubber products are widely used, there are many varieties. The use according to points, usually divided into two major categories of industrial and civilian use. Industrial rubber products mainly include: tires, belts, hoses, offset, tape and tape products, seals, vibration-damping member, latex products, hard rubber, rubber insulation products, rubber rollers and rubber linings.