The basic characteristic of the rubber products
Rubber product refers to the natural and synthetic rubber as raw materials to produce all kinds of rubber products activities, but also the use of waste rubber recycling of rubber products.
The basic characteristics of rubber products:
1. Rubber products molding, after a large pressure to suppress, due to the elastomer is not prepared by the cohesion can not be eliminated, in the mold from the mold, often resulting in very unstable shrinkage (rubber shrinkage, due to different varieties of different ), Must go through a period of time before the gentle stability. Therefore, when a rubber product design at the beginning, regardless of formula or mold, must be carefully calculated with, if not, it is easy to produce product size instability, resulting in low quality products.
2. Rubber is a thermosetting thermosetting elastomer, plastic is hot and cold. Rubber due to the different types of sulfide, the molding curing temperature range, there is a considerable gap, even due to climate change, indoor temperature and humidity affected. Therefore, the production conditions of rubber products, need to be adjusted at any time, if not, it may produce product quality differences.
Rubber Products Classification:
1. General rubber: refers to some or all of the rubber used in place of natural rubber, such as styrene-butadiene rubber, butadiene rubber, isoprene rubber, mainly used in the manufacture of tires and general industrial rubber products. General rubber demand, is the main varieties of synthetic rubber.
2. Butadiene rubber: styrene butadiene rubber is copolymerized from butadiene and styrene, is the largest production of general synthetic rubber, with milk polystyrene rubber, soluble styrene-butadiene rubber and thermoplastic rubber (SBS).
3. Butadiene rubber: butadiene solution by solution polymerization, butadiene rubber has a particularly excellent cold resistance, wear resistance and flexibility, but also has good resistance to aging properties. The majority of butadiene rubber used in the production of tires, a small part for the manufacture of cold products, cushioning materials and tape, rubber shoes. The shortcomings of the butadiene rubber is the resistance to tear resistance, anti-slippery performance is not good.
4. Isoprene rubber: isoprene rubber is polyisoprene rubber abbreviation, the use of solution polymerization method. Isoprene rubber, like natural rubber, has good elasticity and abrasion resistance, excellent heat resistance and good chemical stability. The strength of isoprene rubber (not before processing) is significantly lower than that of natural rubber, but the quality uniformity and processing performance are better than natural rubber. Isoprene rubber can be used instead of natural rubber to produce tires and off-road tires can also be used to produce a variety of rubber products.
5: ethylene propylene rubber: ethylene propylene rubber to ethylene and propylene as the main raw material synthesis, anti-aging, electrical insulation properties and resistance to ozone performance. Ethylene-propylene rubber can be a lot of oil and fill carbon black, low prices, ethylene propylene rubber chemical stability, wear resistance, flexibility, oil resistance and styrene-butadiene rubber close. Ethylene-propylene rubber is widely used, can be used as tire sidewall, strips and tubes and car parts, but also for the wire, cable foreskin and high pressure, ultra-high pressure insulation materials. Can also manufacture shoes, health supplies and other light-colored products.
6. neoprene: it is based on chlorobutadiene as the main raw material, through the homopolymer or a small amount of other monomer copolymerization. Such as high tensile strength, heat resistance, light resistance, excellent aging resistance, oil resistance are better than natural rubber, styrene butadiene rubber, butadiene rubber. Has a strong flame resistance and excellent resistance to flame retardancy, its chemical stability is high, good water resistance. Chloroprene rubber is the disadvantage of electrical insulation properties, poor cold performance, raw rubber is unstable in storage. Chloroprene rubber is widely used, such as used to make transport belts and belts, wires, cables, foreskin materials, rubber processing technology Q & A
1. Why rubber?
The purpose of rubber molding is to make the rubber in the mechanical, thermal, chemical and other effects under the short macromolecule chain, so that the rubber temporarily lost its flexibility and make plasticity to meet the manufacturing process of the process requirements. Such as: easy to mix with the agent, easy to press out pressure, mold pattern clear, stable shape, increase pressure, injection pressure compound fluidity, so that easy to penetrate the fiber material, and can improve the rubber solution and adhesive The Of course, some low viscosity, constant viscosity rubber is sometimes not necessarily masticated, made of standard granular rubber, standard Malaysian rubber (SMR).
2. What factors affect the rubber in the mixer in the plastic
Mixer plastic plastic is a high-temperature plastic blend, the lowest temperature above 120 ℃, usually between 155 ℃ -165 ℃. Raw rubber in the mixer cavity by the high temperature and strong mechanical role, resulting in severe oxidation, in a short period of time to obtain the ideal plasticity. So the impact of the mixer into the plastic plastic refining factors are:
(1) equipment technical performance, such as speed, etc.,
(2) process conditions, such as time, temperature, wind pressure and capacity.
3. Why are all kinds of rubber plastic properties are not the same
The plasticity of rubber is closely related to its chemical composition, molecular structure, molecular weight and molecular weight distribution. Natural rubber and synthetic rubber due to the different characteristics of the structure and performance, in general, natural rubber refining is easier, synthetic plastic refining more difficult. In terms of synthetic rubber isoprene, neoprene near natural rubber, SBR, butyl rubber times, the most difficult nitrile rubber.
4. Why raw plasticity is used as the main quality standard for plasticizers
The plasticity of raw rubber is related to the whole process of manufacturing products difficult to directly affect the physical and chemical properties of vulcanized rubber and the use of the important properties of the product. If the rubber plasticity is too high, will reduce the physical and mechanical properties of vulcanized rubber. and raw plastic plasticity is too low, it will cause the next process of processing difficulties, so that the compound is not easy to mix evenly, rolling, when the semi-finished surface is not smooth, shrinkage, easy to grasp the size of semi-finished products, Difficult to wipe the fabric, resulting in hanging curtains and other phenomena, greatly reducing the adhesion between the cloth layer. Plasticity will cause the plastic material performance and physical and mechanical properties are inconsistent, and even affect the use of products inconsistent performance. Therefore, the correct grasp of raw plasticity is a problem can not be ignored.
5. What is the purpose of mixing?
Mixing is in accordance with the provisions of the compound formula with the proportion of ingredients, the raw rubber and a variety of mixing agent through the rubber equipment mixed together, and make all kinds of complex evenly dispersed in the raw rubber. The purpose of mixing the compound is to obtain the physical and mechanical properties of uniform indicators, in line with the provisions of the formula compound properties, in order to facilitate the next operation and ensure the quality of finished product requirements.
6. Why with the agent group
Resulting in the combination of knives for the reasons are: raw rubber refining is not sufficient, roller height is too large, the roll temperature is too high, the capacity is too large, powder mixture with coarse particles or knots, gel and so on. Improve the approach is to take specific circumstances: full plastic refining, appropriate to adjust the small roll distance, reduce the roll temperature, pay attention to the feeding method; powder drying and screening; mixing when appropriate to cut.
7. excessive amount of carbon black in the compound Why do you have a "dilution effect"
The so-called "dilution effect" is due to the amount of carbon black in the rubber formula, the amount of rubber is relatively reduced in number, resulting in close contact between carbon black particles, and can not be well dispersed in the compound, which Is the "dilution effect." This is because there are many large particles of carbon black particles in the presence of rubber molecules can not penetrate into the carbon black particles inside the body to reduce the interaction between rubber and carbon black, strong decline and fail to achieve the desired reinforcement effect.
8. What are the effects of the structural properties of carbon black on the properties of the compounds?
Carbon black is produced by thermal decomposition of hydrocarbon compounds. When the raw material is natural oil (its components are mainly aliphatic hydrocarbons), it forms a six-membered ring of carbon. When the raw material is heavy oil (high aromatic content), it is further dehydrogenated due to the six-membered ring containing carbon Condensation to form a polycyclic aromatic compound, resulting in carbon atoms of the hexagonal network structure level, this layer 3-5 overlapping to become a crystal. The spherical particles of carbon black are amorphous crystals composed of several groups of crystals without any standard orientation. The circumference of the crystal contains an unsaturated free bond, which bonds the carbon black particles to each other and forms a small branch of the branch, which is called the structure of the carbon black.
The structure of the carbon black varies from one method to another, and the structure of the carbon black is higher than that of the carbon black and the structure of the acetylene black is the highest. In addition, the structure of the carbon black is affected by the raw material and the aromatic content of the raw material is high , The structure of the carbon black is high, the yield is high; the other hand, the structure is low, the yield is also low. The smaller the diameter of the carbon black particles, the higher the structure. In the same particle size range, the higher the structure, the more easily pressed, and the product surface smooth, shrink small. The structure of the carbon black can be measured by the size of the oil absorption, in the same particle size, the oil absorption value that the structure is high, otherwise it means low structure. Highly structured carbon blacks are difficult to disperse in synthetic adhesives, but soft synthetic adhesives require higher modulus carbon blacks to improve their strength, and fine particle high structural carbon blacks can improve the abrasion resistance of tread rubber. Low-structure carbon black has the advantage of high tear strength, elongation, large tensile strength, low hardness, soft rubber, heat is also smaller, but the wear resistance than the same size and high structural carbon black difference.
9. Why does carbon black affect the scorch properties of the compound?
The effect of carbon black on the scorch time of the compound: the structure of the high scorch time is short; the smaller the particle size of the carbon black, the shorter the scorch time. Carbon black particles surface properties of the impact of scorch: mainly refers to the surface of carbon black oxygen content, high oxygen content, PH value is low, acidic, such as slot black, scorch longer. The amount of carbon black on the impact of scorch time: the amount of energy can significantly shorten the scorch time is due to the increase in carbon black, combined with rubber and more tend to promote scorch. The effect of carbon black on the curing time of the rubber in different curing systems is different.
10. What is a kneading, what is the second paragraph of mixing
A kneading is a plastic compound and a variety of compounding agents (for some difficult to disperse or less with the amount of agent can be pre-made masterbatch) according to the process requirements to join one by one, that is, in the mixer to do masterbatch Refining, and then in the tablet machine by adding sulfur or other curing agent and some should not be added in the mixer inside the super-accelerator. In short, a kneading is not in the middle of the park and the completion of the mixing.
Two kneading is the first addition of vulcanizing agent and super accelerator other than the combination of raw materials and raw rubber evenly mixed into the masterbatch, the next piece of cooling, parking for a certain period of time, and then in the mixer or mill Add the process to add the vulcanizing agent.
11. Why should the film be cooled before storage?
Tablet cutting machine down the film temperature is high, if not immediately cooling, it is easy to produce early vulcanization, but also glue, to the next process cause trouble. I plant from the tablet machine down, through the film cooling device soaking agent, dry, sliced, is for this purpose. General cooling requirements is to cool the film temperature below 45 ℃, rubber material storage time should not be too long, otherwise it will cause rubber spray cream.
12. Why control the sulfur temperature below 100 ℃
This is because the mixing compound in the sulfur and accelerator, if the temperature exceeds 100 ℃, it is likely to cause early curing of the rubber (ie scorch). In addition, the sulfur dissolved in the rubber at high temperatures, after cooling sulfur agglutination in the rubber surface, resulting in spray cream, and will cause uneven dispersion of sulfur. Rubber
13. Why should we put a piece of film for a certain period of time before use?
There are four kinds of plastic film after cooling: (1) to restore the fatigue of the compound, relaxation of the mechanical stress suffered by mixing; (2) to reduce the shrinkage of the compound; (3) (4) to make rubber and carbon black between the further generation of rubber, improve the reinforcement effect.
14. Why should we strictly enforce the dosing and pressurizing time?
Dosing sequence and pressure time are important factors affecting the quality of mixing. Segmented dosing can improve the mixing efficiency and increase its uniformity, and the order of addition of certain drugs is also its special provisions, such as: liquid softener must not be added with the carbon black, so as not to agglomerate. So must be strictly implemented sub-dosing. The pressure is too short rubber and the drug can not be fully rubbed and refined, resulting in uneven mixing; such as the pressure is too long mixing room temperature is too high, affecting the quality, but also reduce efficiency. Therefore, the pressure must be strictly enforced.
15. What is the effect of loading capacity on the quality of blended plastic
The capacity is usually 50-60% of the total capacity of the mixer mixing chamber.If the capacity is too large, the mixing without enough space, can not be fully stirred, resulting in mixed Refining is not uniform; temperature rise, easy to cause the rubber from the sulfur; also cause the motor overload. The capacity is too small, there is no sufficient friction between the rotor resistance, there is idling, the same cause uneven mixing, the quality of the compound is affected, but also reduce equipment utilization.
16. When the compound is kneaded, why is the liquid softening agent added?
When the compound is kneaded, if the liquid softener is added first, it will cause the raw rubber to excessively expand and affect the mechanical friction between the glue and the filler, reduce the mixing speed of the compound, and also cause the uneven dispersion of the powder , and even the group. So when the liquid softener is generally the last to join.
17. Why mixing the compound for a long time will be "self-sulfur"
(1) the use of vulcanizing agent, accelerator too much; (2) the capacity of plastic loaded, mixing machine temperature is too high, the film is not enough cooling; (3) the use of curing agent, ) Or prematurely add sulfur, uneven dispersion of drugs caused by accelerator and sulfur local concentration; (4) improper parking, that is, the parking place temperature is too high, the air is not flowing.
18. Why the mixer mixing compound to have a certain wind pressure
Mixing, the mixer mixing room in addition to raw rubber and medicine, there is a considerable part of the existence of the gap, if the pressure is insufficient, raw rubber and medicine can not get enough friction kneading, resulting in mixing is not and increase the pressure, the compound will be up and down around by a strong friction pinch refining, so that raw rubber and mix agent quickly mixed evenly. In theory, the greater the pressure the better, but due to equipment and other restrictions, in fact, the pressure can not be unlimited, in general, the wind pressure to 6Kg / cm2 or so as well.
19. Why open-type mixing machine two rollers to have a certain speed ratio
The purpose of the open mixing machine is to strengthen the shear effect, to produce mechanical friction and molecular chain breakage of the compound, and to promote the dispersion of the compounding agent. Another roll speed is slow, but also conducive to operation, is conducive to safe production.
20. why the mixer will produce folder thallium phenomenon
(2) lack of wind pressure, (3) improper operation, such as when the softener is not pay attention to the attention of the device, such as: , Often make the top bolt and the mixer wall wall glue on the material, if not timely cleaning, over time will be affected.
21. Why is the squeeze film
(2) mixing the temperature of the mixing chamber at the end of the mixing; (2) mixing the temperature of the mixing chamber at the end of the mixing; (2) mixing the temperature of the mixing chamber at the end of the mixing; (3) the amount of filler in the formula is too large, are possible. As the kneading is not good, the compound is compressed. After the pressure of the compound to be added with plastic plastic or plastic, to be pressed after the discharge, and then for technical treatment. Rubber - technology network