Thermoplastic elastomer TPE, also known as synthetic rubber or synthetic rubber. Its products not only have the high elasticity, aging resistance and oil resistance of traditional cross-linked vulcanized rubber, but also have the characteristics of convenient processing and wide processing methods.
TPE plastic is mainly composed of two parts, one is plastic, as the continuous phase, and the other is rubber as the dispersed phase. Usually rubber needs to be combined with softening oil or plasticizer. Vulcanizing agent and some auxiliary additives are also essential. In addition, in order to reduce the cost or improve the performance of some aspects, some inorganic fillers will also be added. According to the material composition, it can be divided into: styrene (SBS, SIS, SEBS, SEPS), olefins (TP0, TPV), diene. Class (TPB, TPI), vinyl chloride (TPVC, TCPE), urethane (TPU), ester (TPEE), amide (TPAE), organic fluorine (TPF), silicone and vinyl, etc. It covers almost all areas of synthetic rubber and synthetic resin. Here are some common components of TPE.
However, the TPE thermoplastic elastomer formulation system has many components. Due to the structural differences of the components, the mechanism is not clear, which brings great difficulty to the flame retardant treatment. There is also a great safety hazard in the use process, which gives TPE The use of the product brings certain limitations. So, what difficulties can the TPE flame retardant treatment encounter?
Flame retardant selection is difficult
The compatibility between the flame retardant and the substrate is poor. When the amount of the flame retardant added in the elastic system is slightly larger, especially in the halogen-free flame retardant, the TPS elastic modulus, flexibility, mechanical properties, and wear resistance are greatly reduced. The melt fluidity is deteriorated, the elastomer is difficult to form, and the surface is prone to migration of the flame retardant, which constitutes a polluted environment.
The mechanism of flame retardant is not clear
The TPS system is mainly a multi-phase mixed structure of rubber, polyolefin resin, plasticizer and filler. The halogen-free flame retardant of polyolefin resin has relatively mature formula and examples. But SEBS and polyolefin PP, PE The flame retardant mechanism is actually not the same. A flame retardant is difficult to flame retard a variety of plastic components at the same time.
Plasticizer reduces flame retardancy
In order to reduce the hardness, TPE plastic is softer in hand. It is often necessary to add plasticizer (white oil), usually based on four kinds of 26#, 32# white oil and 70# white oil. Due to the limiting oxygen index of four oils And the difference in fluidity, while the natural flammability of oil substances greatly reduces the flame retardancy of elastomers, so how to solve the relationship between plasticizer and flame retardant in the production of low hardness products, how to choose the type of white oil is very important.
Based on the difficulties that may be encountered above, what are the practical problems that the flame retardant TPE may encounter during the processing? What is the corresponding solution?
Wire surface is not smooth
TPE wire processing often occurs, usually due to the temperature is not adjusted and the mixing of the flame retardant is not uniform, it may also be caused by improper selection of the mold, of course, also has a great relationship with the material formulation. Experienced processors will rule out Equipment problems, after repeated debugging can also find the right temperature, but the choice of appropriate materials, and specific formulas must be carefully considered by the engineers. It is recommended to communicate with the raw material suppliers, know the material properties and processing considerations, choose the right The material will do more with less! TPU wire will be better processed than TPE wire.
Wire surface precipitation
No material has been guaranteed to be completely precipitated so far, and the specific precipitation is: The surface is white, oily or foggy. With the current technology, this problem has not been solved. It is recommended that customers choose the best. Choose a material with a slightly white surface. This precipitation will not affect its physical properties and electrical performance. The surface oily material should not be used. It is easy to fall off during use and peel off. In addition, there are also some weights, good materials. Its precipitation is slight, and it is not easy to happen in the short term, even if it is lightly rubbed by hand.
Surface scratching and peeling off the glue
Scratch is caused by the addition of PP and PE in the material, which can be improved. Some manufacturers have done that the product will not be white, but TPE is more difficult than TPU. If the skin is peeled off, the level is very general. Here is still to say, recipe! Craft!
Processing difficulty
Elastomers are characterized by slower processing speeds, which are about 50% slower than PVC. The temperature is not well regulated, and a lot of materials are wasted when adjusting the machine. In addition, washing the machine before cooking, waste is not small. These are not In the production, sometimes the production in the front stage is normal, and the processing in the back-end processing is problematic. In this case, it is necessary to explain that the sub-card material is risky and should be used with caution.
Flame retardant TPE/TPU plastic is a very unique material. TPE/TPU flame retardant problem still requires everyone to do more work in material selection, formulation and process. In general, it is recommended to use liquid flame retardant to reduce hardness while improving. Flame retardant, reduce the amount of powder flame retardant added, can improve the transparency of the product, improve the compatibility of the flame retardant with the substrate by using the compatibilizer, improve the precipitation and greatly improve the mechanical properties; the special screw distribution is adopted in the process. Improve the dispersion of flame retardant in the system, improve the flame retardant efficiency, improve the appearance; adopt new silicone flame retardant, condensed phase flame retardant mechanism, form a cracking carbon layer with strong oxidation resistance, and improve flame retardant efficiency.