Rubber production process

2018-05-05 14:32:41 zhongqi 0

1. Basic process flow

With the rapid development of modern industry, especially the chemical industry, there are many kinds of rubber products, but the production process is basically the same. The general solid rubber (raw rubber) as raw materials, its production process includes:

Preparation of Raw Materials→Plastics→Mixing→Molding→Vulcanization→Repair→Inspection

2. Raw material preparation

The main materials of rubber products are raw rubber, compounding agents, fiber materials and metal materials. Among them, raw rubber is a basic material; compounding agents are auxiliary materials added to improve certain properties of rubber products; fiber materials (cotton, hemp, wool and various man-made fibers, synthetic fibers) and metal materials (steel wires, copper wires) It is used as a skeleton material for rubber products to enhance mechanical strength and limit product variations.

During raw material preparation, the ingredients must be accurately weighed according to the formula. In order to allow the raw rubber and compounding agents to mix evenly with each other, some materials need to be processed:

1. Basic process flow

With the rapid development of modern industry, especially the chemical industry, there are many kinds of rubber products, but the production process is basically the same. The general solid rubber (raw rubber) as raw materials, its production process includes:

Preparation of Raw Materials→Plastics→Mixing→Molding→Vulcanization→Resetting→Inspection

2. Raw material preparation

The main materials of rubber products are raw rubber, compounding agents, fiber materials and metal materials. Among them, raw rubber is a basic material; compounding agents are auxiliary materials added to improve certain properties of rubber products; fiber materials (cotton, hemp, wool and various man-made fibers, synthetic fibers) and metal materials (steel wires, copper wires) It is used as a skeleton material for rubber products to enhance mechanical strength and limit product variations.

During raw material preparation, the ingredients must be accurately weighed according to the formula. In order to allow the raw rubber and compounding agents to mix evenly with each other, some materials need to be processed:

Raw rubber should be softened in a drying room at 60--70°C, and then cut into plastic and break into small pieces;

Bulk ingredients such as paraffin, stearic acid, rosin, etc. must be crushed;

Powdery compounding agent needs to be screened and removed if it contains mechanical impurities or coarse particles;

Liquid ingredients (pine tar, coumarone) need to be heated, melted, evaporated, filtered, and filtered;

The compounding agent should be dried, otherwise, it is easy to agglomerate and cannot be uniformly dispersed during the mixing process. Bubbles occur during vulcanization, which affects the product quality.

3. Mastication

Raw rubber is elastic and lacks the necessary properties (plasticity) during processing, so it is not easy to process. In order to improve its plasticity, it is necessary to plasticize the raw rubber; in this way, the compounding agent is easily and uniformly dispersed in the raw rubber at the time of mixing; at the same time, it also helps to increase the permeability of the rubber in the process of rolling and forming (infiltration). Fiber fabric) and molding fluidity. The process of degrading long-chain molecules of raw rubber to form plasticity is called plastication. Raw rubber plastic refining methods are mechanical plastic refining and thermoplastic refining two. Mechanical plastication is the use of mechanical squeezing and frictional forces of plasticizers at very low temperatures to degrade long-chain rubber molecules and change from a highly elastic state to a plastic state. Thermoplastic refining is the introduction of hot, compressed air into the raw rubber. Under the action of heat and oxygen, the long-chain molecules degrade and become shorter, resulting in plasticity.

4. Mixing

In order to adapt to a variety of different conditions of use, to obtain a variety of different properties, but also to improve the performance of rubber products and reduce costs, you must add different compounding agents in the raw rubber. Mixing is a process in which raw rubber and compounding agent after mastication are mixed and placed in a rubber mixing machine, and the compounding agent is completely and uniformly dispersed in the raw rubber through mechanical mixing. Mixing is an important process in the production of rubber products. If the mixing is not uniform, the effects of rubber and compounding agents cannot be fully exerted, and the performance of the products will be affected. The rubber compound obtained after mixing is known as a compound rubber. It is a semi-finished material for manufacturing various rubber products. It is commonly called a rubber compound and is usually sold as a commodity. Buyers can use a rubber compound to directly form, vulcanize, and form a compound. Needed rubber products. Depending on the formulation, the mix has a range of different grades and varieties with different properties, offering choices.

5. Molding

In the production process of rubber products, a variety of processes with different shapes and sizes are pre-formed by using a calender or an extruder, which is called molding. Molding methods include:

Calendering Suitable for the manufacture of simple sheet and plate products. It is a method of pressing a compounded rubber into a certain shape and a certain size of a film through a calender, which is called calendering. Some textile products made of rubber (such as tires, tapes, hoses, etc.) must be coated with a thin layer of glue (also known as glue or glue on fibers), and the gluing process is usually done on calenders. Fiber materials need to be dried and dipped before calendering. The purpose of drying is to reduce the moisture content of the fiber material (so as to prevent the water from evaporating and foaming) and to increase the temperature of the fiber material to ensure the quality of the calendering process. Dip is a necessary process before the glue is attached, the purpose is to improve the binding properties of fiber materials and rubber.

Extrusion molding For more complex rubber products, such as tire treads, hoses, wire surface coating needs to be manufactured by extrusion molding. It is a method of putting a certain amount of plastic compound into the hopper of the extruder. Under the extrusion of the screw, it is extruded through a variety of die shapes (also called templates). Before, the compound must be preheated to make the compound soft and easy to extrude, resulting in a rubber product with a smooth surface and accurate dimensions.

Molding Molding can also be used to make some rubber products with complex shapes (such as leather cups and seals). With the help of the molded yin and yang molds, the rubber compound is placed in a mold and heated.

Vulcanization

The process of converting plastic rubber into elastic rubber is called vulcanization. It involves adding a certain amount of a vulcanizing agent (such as sulfur, a vulcanization accelerator, etc.) to a semifinished product made of raw rubber (carried out in a vulcanization tank). Heating and keeping temperature at the temperature enable the crosslinks between the linear molecules of the raw rubber to form a network structure by forming a "sulfur bridge", so that the plastic material becomes a vulcanizate with high elasticity. Because the crosslinks are mainly composed of sulfur, they are called "vulcanization." With the rapid development of synthetic rubber, there are many types of vulcanizing agents. Besides sulfur, there are organic polysulfides, peroxides, and metal oxides. Wait. Therefore, any process that can transform a linear rubber plastic into a three-dimensional network structure is called vulcanization. Any material that can act as a "bridge" in rubber materials is called "curing agent."

Vulcanized elastic rubber is called vulcanized rubber, also known as soft rubber, commonly known as "rubber." Vulcanization is one of the most important processes in rubber processing. Various rubber products must be vulcanized to obtain ideal performance. Unvulcanized rubber is of little use in use, but it does not use sulfur (sulfurization is not enough, the vulcanization time is not enough to achieve the best state) and over-sulfur (over-curing time, performance is significantly reduced) make Rubber performance is declining. Therefore, the curing time must be strictly controlled during the production process to ensure that the vulcanized rubber products have the best performance and the longest service life.

7. Supplementary measures

In order to achieve performance, additional measures should be added to the production process:

7.1 increase strength - with hard carbon black, mixed with phenolic resin;

7.2 increase wear resistance - with hard carbon black;

7.3 High airtightness requirements - use less volatile components;

7.4 increase heat resistance - using a new vulcanization process;

7.5 increase cold resistance - through the disassembly of raw rubber inlaid, to reduce the crystallization tendency, the use of low temperature plasticizer;

7.6 Increased flame resistance - no flammable additives, no softeners, no flame retardants (eg antimony trioxide)

7.7 increase oxygen resistance, ozone resistance - the use of protective agents against diamines;

7.8 improve the electrical insulation - with a high structural filler or metal powder, with antistatic agent;

7.9 increase the magnetic - using ferrite powder, aluminum nickel iron powder, iron powder, etc. as a filler;

7.10 improve water resistance - the use of lead oxide or resin vulcanization system, with a low water absorption filler (such as barium sulfate, clay);

7.11 Improve oil resistance - fully cross-linked, less plasticizers;

7.12 increase the acid and alkalinity - multi-purpose fillers;

7.13 improve high vacuum - with a small volatile additives;

7.14 Reducing Hardness - Massive Filling of Softeners

8. Classification of rubber products and their application in automobiles

Rubber products are widely used and there are many varieties. According to the use of points, usually divided into two categories of industrial and civilian use. Industrial rubber products mainly include: tires, tapes, hoses, offset, tape and tape products, seals, vibration reduction parts, latex products, hard rubber products, rubber insulation products, rubber rollers and rubber linings.


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