1, rubber sticky and copper wire black analysis rubber cable is composed of multi-strand thin copper wire conductor, outsourcing of rubber insulation and rubber sheath of a soft and removable cable varieties. In general, including general-purpose rubber soft cable, welding machine cables, submersible motor cables, radio cables and photographic equipment, and other varieties of light cables. Black copper cable black is caused by many factors, not only rubber formula, but also with the copper wire itself in the state, the rubber processing technology, rubber curing process, the structure of the cable, jacket rubber formula , The production environment and many other factors. 1, rubber sticky and copper wire black analysis 1.1 copper wire itself in the 20th century since the fifties and sixties, most domestic manufacturers are using ordinary copper rod, copper content of 99.99%, are oxygen copper rod, the production method is copper ingot heated by the multi-channel After rolling black copper rod system, through the large, medium and small copper rods will be made of relatively thin copper wire. Because copper itself is not oxygen-free copper, the surface of the copper wire is inevitable in the process of oxidation. By the 1980s, the introduction of advanced production technology of oxygen-free copper rod and domestic production of oxygen-free copper rod technology, the entire wire and cable industry are using an oxygen-free copper rod, which is undoubtedly improved Black wire problem. However, due to the copper rod processing, especially the mastery of toughing process and the processing of good copper core storage conditions are poor, so that the copper core itself has a slight oxidation, which is one of the reasons black copper wire. 1.2 The reason for the rubber formula The 20th century, the fifties, rubber insulation are used natural rubber and SBR and formula. Since the insulating rubber is in direct contact with the copper wire, sulfur can not be used directly as a vulcanizing agent, that is to say, the copper wire can be made black even with a small amount of sulfur. Some compounds that decompose free sulfur must be used, such as the TMTD accelerator and VA-7 as mentioned above, along with some vulcanization accelerators to increase the vulcanization rate and cure rate, and ensure the physical and mechanical properties of the insulating rubber And electrical performance. However, from the flexibility of the rubber insulation, strength and permanent deformation, are not as good as adding sulfur rubber (if you do not consider black copper wire). Decades of practice have confirmed that TMTD can not solve the problem of blackening of copper wire. In addition, the insulating rubber to have a variety of colors, red, blue, yellow, green, black is the basic color, the appearance of these colors will also promote rubber sticky and copper black. The main filler in the formulation is light calcium carbonate and talc. Due to the price relationship, some manufacturers use cheaper calcium carbonate and talc to reduce costs. These fillers have coarse particles with large free base content and impurities So, physical and mechanical properties are relatively poor, poor electrical properties, but also easily lead to black copper wire. There are plants with activated calcium carbonate to improve the physical and mechanical properties of insulating rubber, and most of the active calcium is treated with stearic acid, this acid is also contributed to black copper wire. VA-7 curing agent can improve the blackness of copper wire, but due to the degree of curing is not enough, the permanent deformation of rubber, will cause rubber sticky. Especially after adding the accelerator ZDC, the curing speed is increased. In order to prevent the scorching, a promoter DM is added to delay the scorch time. From the perspective of the structure of accelerator ZDC, one zinc metal is attached to the two adjacent sulfur in the TETD structure, and the structure is: SSH5C2∥H5C2> NCS-Zn-SC-NN-CSSCN 2, from the wire and cable structure analysis 2.1 copper catalytic aging is an important reason for rubber sticky Soviet Union Cable Research Institute test proved: copper sulfide infiltration from the rubber contact with the insulating rubber, 1.0-2.0mm thickness of the insulating rubber containing copper 0.009-0.0027% . As we all know, trace amount of copper on the rubber has a great role in the destruction, that is, we usually say that the heavy metal rubber catalytic aging. During the process of insulating vulcanization, Thiuram isolated a number of free sulfur compounds which reacted with copper to form active copper-containing groups: CH3-CH2-CH-C-CH2-││SS││CuCu During aging, the weaker -S- The bond breaks to form an active copper-containing group: Cu-S-, which interacts with the rubber and at the same time with oxygen, destroying the long-chain molecules of the rubber and making the rubber soft and viscous, which is a combination of low molecular chains. The French Institute of Rubber Research tackles the recurrence of problems also pointed out: If the rubber contains harmful metals, such as: copper, manganese and other heavy metal salts, then regardless of the type of accelerator, will occur rubber sticky phenomenon. 2.2 rubber cables in the sulfur to the insulation rubber and copper surface migration Before the Soviet scientists using radioactive isotopes confirmed the possibility of sulfur diffusion in cable sheathing rubber. In natural rubber based vulcanizates, the diffusion coefficient of free sulfur is about 10-6 cm2 / s at a temperature of 130-150 ° C. Continuous vulcanization of the production plant, curing sheath rubber, the temperature between 185-200 ℃, the diffusion coefficient even greater. Due to the diffusion of free sulfur in the rubber sleeve, the structure of the thiuram rubber has been changed and polysulfide bonds may form. These polysulphides migrate by chemical decomposition and compounding, "chemical diffusion." As a result of the migration, not only can the structure of the insulating rubber be changed, the heat resistance thereof is lowered, and sulfur reacts with the copper surface to form copper sulfide and cuprous sulfide, resulting in blackening of the copper wire. In turn, copper sulphide and cuprous sulphide accelerate the aging of the rubber, which in turn leads to stickiness. 3, processing technology reasons 3.1 The reasons for the processing of rubber In the natural rubber and styrene-butadiene rubber-based insulation formula, the natural rubber need to be plasticized to improve the plasticity of rubber. Some manufacturers in order to yield, with mixer plastic, but also add a small amount of chemical plasticizers - accelerator M to improve plasticity. If plasticizing temperature and raw rubber filter when the temperature control is not good, there is a high temperature above 140 ℃, when the raw rubber on the open mill slowly through the drum, and above the plastic because of thermal oxygen and accelerator M at the same time Role, you will find the surface of the rubber seems to be coated with a layer of oil, in fact, the rubber molecules in the promotion of chemical plasticizers more severely broken chain, resulting in a relatively soft and sticky smaller molecular weight rubber. Although later mixed with styrene-butadiene rubber and insulating rubber, these small molecular weight of natural rubber is evenly dispersed in the rubber compound, these compounds extruded on the copper wire for continuous vulcanization, the time may not see any problems , But has laid a hidden danger for the rubber sticky copper wire, that is to say, these small molecular weight natural rubber will first appear partial sticky copper wire phenomenon. Insulation rubber plus curing agent and accelerator process is also very important. Some small factories in the mill with curing agent, is to be equipped with curing agent in the middle of the jar into the middle of a lot, but less on both sides. When the curing agent eaten into the rubber, the number of flip triangle less vulcanizing agent in the rubber will be unevenly distributed. This squeeze continuous curing, curing agent containing more places are prone to copper black phenomenon, in a black place for a long time, there will be rubber sticky copper wire phenomenon. 3.2 reasons for insulating rubber vulcanization Some enterprises in pursuit of production, continuous vulcanization pipe is only 60 meters long, the steam pressure is 1.3Mpa, and vulcanization speed to 120 meters / min, so that insulation rubber in the tube residence time of only 30 seconds . Eraser itself is a poor conductor of heat, insulated core surface temperature greater than 190 ℃, when the temperature heat transfer to the inner layer of rubber in contact with the copper wire, but also by copper heat, copper wire up to the inner rubber temperature close , Vulcanized rubber wire core has a vulcanized tube. This layer of rubber temperature is relatively low, about 170 ℃, stay only a few seconds out of the vulcanization tube, into the cooling and closing line, the insulation rubber will be inadequate curing. In order to achieve adequate vulcanization. The amount of accelerator TMTD (used as a curing agent) is as high as 3.4%. Excess curing agent is released during vulcanization Mechanical Seal And Nozzle,Carbide Garden Hose Nozzle,Tungsten Carbide Hose Nozzle,Carbide Hose Nozzles Zigong Brace Cemented Carbide Co.,Ltd , https://www.bracecarbide.com