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1. Basic technological process
There are many kinds of rubber products, but the production process is basically the same.
The basic process of rubber products made of general solid rubber -- raw rubber includes six basic processes: plastic refining, mixing, calendering, extrusion, molding and vulcanization.
Of course, the preparation of raw materials, finished products, inspection and packaging and other basic processes are also indispensable.
The processing of rubber mainly solves the contradiction between plasticity and elasticity.
Through various technological means, the elastic rubber becomes the plastic-refining rubber, which is then made into semi-finished products by adding various dosages, and then the plastic semi-finished products become the rubber products with high elasticity and good physical and mechanical properties by curing.
Preparation of raw materials
1. The main raw material of rubber products is raw rubber, which is grown in tropical and subtropical rubber trees and collected by artificial cutting of bark.
2. Various coordination agents are auxiliary materials added to improve some properties of rubber products.
3. Fiber materials (cotton, linen, wool, various man-made fibers, synthetic fibers, metal materials and steel wires) are used as the skeleton material of rubber products to enhance mechanical strength and limit product deformation.
In the preparation of raw materials, ingredients must be weighed accurately according to the formula.
In order to mix the raw glue and the coordination agent evenly, the material needs to be processed.
Raw rubber in 60-70 ℃ after baking chamber in soft gel and gel breaking into small pieces, compound has a block.
If paraffin, stearic acid, such as rosin to crush.
If the powder contains mechanical impurities or coarse grains, it needs to be screened to remove liquid such as pine tar and gumalon, which need to be heated, melted, evaporated water and filtered impurities. If the dosages are dried, it will be easy to agglomerate.
Third, the molding
The raw glue is elastic and lacks the necessary plasticity during processing, so it is not easy to process.
In order to improve its plasticity, it is necessary to plasticize the raw glue. In this way, the compound can be dispersed evenly in the raw glue during mixing. Meanwhile, in the process of rolling and molding, it is also helpful to improve the permeability of the glue to infiltrate into the fiber fabric and the molding fluidity.
The process of breaking down the long chain molecules of raw glue to form plasticity is called plasticity.
There are two methods of plastication: mechanical and thermoplastic.
Mechanical plastication is a process in which long chain rubber molecules are degraded short by mechanical extrusion and friction by the plasticator at not too high temperature.
Thermoplastic refining is to pass hot compressed air into the raw glue under the action of heat and oxygen to shorten the degradation of long chain molecules so as to obtain plasticity.
In order to adapt to various conditions of use, obtain various properties, and also to improve the performance of rubber products and reduce the cost, it is necessary to add different additives in the raw rubber.
Mixing is a process in which the plasticated raw glue is mixed with the mixing agent, and the mixing agent is dispersed completely and evenly in the raw glue by mechanical mixing in the mixing machine.
Mixing is an important process in the production of rubber products. If the mixing is not uniform, the role of rubber and compound cannot be fully played to affect the performance of the products.
The rubber obtained after mixing is known as mixed rubber which is the semi-finished material for making various rubber products.
According to the formula, okay?
Mixed rubber has a range of properties of different brands and varieties?
Five, the molding
In the production of rubber products in the use of a rolling machine or extruder pre-made shape of a variety of different sizes process?
It's called molding.
There are methods of forming
1. Rolling molding
Suitable for making simple sheet and plate products.
It is the mixing of rubber through the rolling machine into a certain shape, a certain size of film is called rolling molding.
For example, the textile fiber materials such as tire, rubber cloth and rubber tube must be coated with a thin layer of glue.
The gluing process is generally completed on the calender.
Before calendering, the fiber material needs to be dried and soaked with glue. The purpose of drying is to reduce the water content of the fiber material so as to avoid water evaporation and foaming.
And improve the temperature of fiber materials to ensure the quality of rolling process.
Impregnation is the necessary procedure before gluing in order to improve the binding performance of fiber and glue.
2. Extrusion molding
For more complex rubber products?
Like the tire tread, rubber tube, metal wire surface coating rubber needs to be produced by the method of extrusion molding.
It is a method of continuous molding by means of various mouth shapes, also called templates, under the extrusion of the internal screw rod of the hopper with certain plasticity.
Before the extruding, the rubber material must be preheated to make it soft and easy to extrude so as to obtain rubber products with smooth surface and accurate size.
You can also use moulding to make some rubber products with complex shapes such as leather bowls and sealing rings.
With the molding of the Yin, Yang mold plastic material placed in the mold heating molding.
Called plastic rubber into the process of elastic rubber vulcanization it is to a certain amount of curing agent such as sulphur, vulcanization accelerator join the semi-finished products made from raw rubber in the prescribed temperature vulcanizing tank heating, heat preservation of raw rubber linear generated by sulfur "bridge" between the molecules and got behind each other hand in 3 d mesh structure making plastic rubber vulcanizates with high elasticity.
Because the crosslinked bond is mainly composed of sulfur, it is called "vulcanization".
With the rapid development of synthetic rubber, there are many varieties of vulcanizing agents besides sulfur, such as organic polysulfide, peroxide and metal oxide.
Therefore, the process of transforming linear plastic rubber into three-dimensional network elastic rubber is called vulcanization. Any material that can bridge the rubber material is called vulcanization agent.
The elastic rubber after vulcanization is called vulcanized rubber or soft rubber commonly known as "rubber".
Vulcanization is one of the most important process of rubber processing.
Unvulcanized rubber is of little use value in use, but less sulphur?
If the curing time is not enough to reach the optimum condition and the over-sulfur curing time is exceeded, the performance of rubber will decline significantly.
So you have to strictly control the curing time, right?
In order to guarantee the vulcanized rubber products with the best performance and the longest service life.
Vii. Auxiliary measures
In order to achieve operational performance, additional measures should be added in the production process
1. Increase strength -- phenolic resins mixed with hard carbon black
2. Increase wear resistance -- match hard carbon black
3. High air tightness requirement -- use less volatile components
Increase heat resistance -- new curing process
5. Increase cold resistance -- through unbranched inlays of raw rubber
Decrease crystallization tendency?
Use low temperature resistant plasticizers
6. Increase flame resistance -- no use of flammable auxiliaries, use less softeners, and use flame retardants such as antimony trioxide
7. Increase oxygen resistance and ozone resistance -- adopt diamine protective agents
8. Improve electrical insulation -- match high structure filler or metal powder with antistatic agent
9. Improve magnetic properties -- use strontium iron oxide aluminum nickel iron powder iron barium powder as filler
10. Improve water resistance -- use lead oxide or resin curing system to mix filling agents with lower water absorption, such as barium sulfate and clay
11. Improve oil resistance -- full cross-linking and less use of plasticizers
Increase ph and alkali resistance -- multi-purpose filler
Improve the high vacuum properties -- use less volatile additives