The main mouse pad material of rubber products are raw rubber, various compounding agents, and fiber and metal materials as skeleton materials. The basic production process of rubber products includes six basic processes of mastication, mixing, calendering, extrusion, molding and vulcanization. The rubber processing process is mainly to solve the contradiction between plasticity and elasticity. Through various processing means, the elastic rubber becomes a plasticized plastic compound, and a semi-finished product is prepared by adding various compounding agents, and then it is plasticized by vulcanization. The semi-finished products are turned into rubber products with high elasticity and good physical and mechanical properties.
Rubber processing technology
Mastication process
Mouse pad material roll is a process in which raw rubber is transformed from a tough elastic state into a soft, easy-to-process plastic state by mechanical stress, heat, oxygen or the addition of certain chemical agents. The purpose of raw rubber mastication is to reduce its elasticity, increase plasticity, and obtain appropriate fluidity to meet various processing processes such as mixing, sub-diffraction, extrusion, molding, vulcanization and glue manufacturing, and sponge rubber manufacturing. Requirements. Mastering proper plasticity and plasticity is critical to the processing of rubber products and the quality of finished products. The plasticity should be reduced as much as possible while meeting the requirements of the processing technology. With the advent of constant viscosity rubber and low viscosity rubber, some rubbers have been directly kneaded without the need for mastication. In the rubber industry, the most commonly used mastication methods are mechanical plasticizing and chemical plasticating. The main equipment used in the mechanical mastication process is an open rubber mixer, a closed rubber mixer and a screw plastic mixer. Chemical plasticization is a method of adding chemicals to the mechanical mastication process to improve the mastication effect. The temperature of the open mill during mastication is generally below 80 ° C, which is a low temperature mechanical mixing method. The mixing temperature of the mixer and the screw mixer is above 120 ° C, and even as high as 160-180 ° C, which is a high temperature mechanical mixing. Raw rubber needs to be pre-baked, cut, glued and broken before it can be plasticized. Mastication characteristics of several kinds of rubber: When the natural rubber is masticated with an open mill, the temperature of the roller is 30-40 ° C, the time is about 15-20 min; when the temperature is above 120 ° C by the internal mixer, the time is about It is 3-5min. The Mooney viscosity of styrene-butadiene rubber is more than 35-60. Therefore, styrene-butadiene rubber can also be used without plasticming, but after disintegration, the dispersibility of the blending machine can be improved. The butadiene rubber has cold flow and lacks mastication effect. . The Mooney viscosity of the butadiene rubber is low, and it is not necessary to masticate. Neoprene has a large plasticity, can be thinned 3-5 times before mastication, and the thin pass temperature is 30-40 °C. The molecular backbone of ethylene propylene rubber is a saturated structure, and it is difficult to cause molecular cracking by mastication. Therefore, it is necessary to select a variety with low Mooney viscosity without mastication. Nitrile rubber has a small plasticity, a high toughness, and a large heat during mastication. When starting the refining, it is necessary to use a low temperature of 40 ° C or less, a small roll pitch, a low capacity, and a segmental mastication, so that good results can be obtained.
Mixing process
Mixing refers to the process of uniformly mixing various compounding agents into the raw rubber on a rubber mixer. The quality of the mixing has a decisive influence on the further processing of the rubber and the quality of the finished product. Even if the compound is well formulated, if the mixing is not good, the dispersing of the compounding agent will be uneven, and the plasticity of the rubber compound will be too high. Or too low, easy to scorch, spray, etc., so that the calendering, pressing, gluing and vulcanization processes can not be carried out normally, but also lead to degradation of product performance. The mixing method is usually divided into two types: open mill mixing and mixer mixing. Both methods are batch mixing, which is currently the most extensive method. The mixing process of the open mill is divided into three stages, namely, the wrapping roll (softening stage of adding raw rubber), eating powder (mixing stage of adding powder) and retorting (the raw rubber and compounding agent are evenly dispersed after eating powder). Stage). The mixing rubber of the open mill is different according to the type, use and performance requirements of the rubber compound, and the process conditions are also different. In the mixing, attention should be paid to various factors such as the amount of glue added, the order of addition, the roll distance, the roll temperature, the mixing time, the speed and speed ratio of the rolls. Neither can you mix enough and you can’t over-smelt. The mixing of the mixer is divided into three stages, namely, wetting, dispersing and nitrile, and the mixer mixing stone is carried out under high temperature and pressure. The method of operation is generally divided into a mixing method and a two-stage mixing method. A section of the mixing method refers to a method in which the mixing is completed once by an internal mixer and then the mixture is compressed. He is suitable for all natural rubber or rubber with no more than 50% of synthetic rubber. In a mixing operation, batchwise stepwise feeding is often used. In order to prevent the rubber from rising sharply, slow mixing is generally used. It is also possible to use a two-speed internal mixer. The temperature at which sulfur is added must be lower than 100 °C. The order of addition is raw rubber – small material – reinforcing agent – filler – oil softener – discharge – cooling – sulfur and super accelerator. The two-stage mixing method refers to a method in which a mixture of two pieces is kneaded by an internal mixer to prepare a rubber compound. This method is suitable for the rubber compound with a synthetic rubber content of more than 50%, which can avoid the disadvantages of long mixing time and high temperature of the rubber during a mixing process. The first stage mixing is the same as the one-stage mixing method, except that the vulcanization and the active agent are not added. After the mixing, the lower piece is cooled, parked for a certain period of time, and then the second stage is mixed. After mixing evenly, the material is discharged onto the tableting machine and then added with a vulcanizing agent. The sub-mixing method has a shorter mixing time, a lower mixing temperature, a more uniform dispersion of the compounding agent, and a higher quality of the compound. The rubber extrusion speed is slow, the compression deformation is large, the surface is rough, the body temperature is 50-70 ° C, the head temperature is 70-80 ° C, the mouth temperature is 100-105 ° C; the neoprene rubber is not fully heated before being pressed out, the body temperature 50 ° C, head ° °, mouth 70 ° C; ethylene-propylene rubber extrusion speed, shrinkage is small, body temperature 60-70 ° C, head temperature 80-130 ° C, mouth 90-140 ° C. Nitrile rubber has poor extrusion performance and should be fully heated when extruded. The body temperature is 50-60 ° C, and the head temperature is 70-80 ° C. 2.7 Vulcanization Process Earlier, the main purpose of natural rubber was to use a rubber eraser; it was later used to make small rubber hoses. It was not until 1823 that the British chemist Mackintosh invented the rubber in coal tar and applied it to the cloth to make a tarpaulin that could be used to make raincoats and rain boots. However, the raincoat and rain boots melted in the summer and became hard and brittle as soon as winter. In order to overcome this shortcoming, many people were thinking of ways. The American inventor Charlie Goodyear is also experimenting with rubber modification. He puts natural rubber and sulfur together and heats it, hoping to get a substance that remains dry and elastic at all temperatures throughout the year. It was not until February 1839 that he succeeded. One day he mixed the rubber, sulfur and turpentine into the pot (the sulphur was only used for dyeing), and the mixture in the pot was accidentally splashed on the hot stove. To his surprise, the mixture did not melt after falling into the fire, but was burnt as it was, and the incompletely charred mixture remaining in the furnace was elastic. He stripped the spilled thing off the stove and found that he had prepared the elastic rubber he wanted. After continuous improvement, he finally invented the rubber vulcanization technology in 1844. Vulcanization is the last processing step in the production of rubber products. Vulcanization is a cross-linking process in which rubber macromolecules change from a linear structure to a network structure under certain conditions. The vulcanization methods include cold vulcanization, room temperature vulcanization and hot vulcanization. Most rubber products are heat vulcanized. Hot vulcanization equipment includes vulcanization tanks, flat vulcanizing machines ,eat.
