Analysis of the reasons why TPE is difficult to do flame retardant

2022-01-22   Pageview:60

Thermoplastic elastomer TPE (Thermoplastic Elastomer ), also known as synthetic rubber or synthetic rubber. Its products not only have the traditional cross-linked vulcanized rubber of high elasticity, aging resistance, oil resistance and other excellent performance, but also have the characteristics of convenient processing of ordinary plastics, processing methods are wide.

TPE is mainly composed of two parts, one is plastic, as the continuous phase, and the other is rubber as the dispersed phase. Usually the rubber needs to be combined with softening oil or plasticizer with it. Thixotropic agents and some auxiliary additives are also essential.

In addition, some inorganic fillers are filled in order to reduce the cost or improve the performance of a certain aspect. According to the material composition can be divided into: styrene (SBS, SIS, SEBS, SEPS), olefin (TP0, TPV), diene (TPB, TPI), vinyl chloride (TPVC, TCPE), ammonia ester (TPU), ester (TPEE), amide (TPAE), organofluorine (TPF), silicone and ethylene, etc., covering almost Nowadays, almost all fields of synthetic rubber and synthetic resin are covered.

However, there are many components of TPE thermoplastic elastomer formulation system, and due to the differences in the structural properties of each component and the unclear mechanism, it brings a lot of difficulties to the flame retardant treatment, and there are also great safety hazards in the process of use, which brings certain limitations to the use of TPE products. So, what difficulties may be encountered in the TPE flame retardant treatment?

Flame retardant selection is difficult

Poor compatibility of flame retardant and base material. When the amount of flame retardant added to the elastic system is slightly larger, especially in the halogen-free flame retardant, TPS elastic modulus, flexibility, mechanical properties, wear resistance significantly reduced, the melt fluidity becomes poor, the elastomer is difficult to shape, and the surface is prone to flame retardant migration, constituting a polluted environment.

Flame retardant mechanism is not clear

TPS system is mainly a multi-phase hybrid structure of rubber, polyolefin resin, plasticizer and filler. Although there are relatively mature formulations and examples of halogen-free flame retardants for polyolefin resins. However, the flame retardant mechanism of SEBS and polyolefin PP and PE is actually not the same, and it is difficult for a flame retardant to flame retard many plastic components at the same time.

Plasticizers reduce flame retardancy

TPS in order to reduce the hardness is a softer feel, often need to add plasticizers (white oil), usually 26 #, 32 # white oil, 70 # white oil these four kinds of mainly. Due to the differences in the limiting oxygen index and fluidity of the four oils, while the natural flammability of oil substances greatly reduces the flame retardancy of elastomers, so how to solve the relationship between plasticizers and flame retardancy in the production of low hardness products, how to choose the type of white oil is crucial.

Based on the above difficulties, what are the practical problems that may be encountered in the processing of flame retardant TPE? What are the corresponding solutions?

 The surface of the wire is not smooth

TPE wire processing often occurs, generally due to the temperature is not well adjusted and flame retardant mixture is not uniformly caused, may also be caused by incorrect selection of the mold, of course, with the material formula also has a great relationship.

Experienced processing plant will exclude the problem of equipment, after repeated debugging can also find the right temperature, but the selection of suitable materials, and specific formulations will be engineers carefully.

It is recommended to communicate with raw material suppliers to know the physical properties of the material and processing considerations, choose the right material, will get twice the result with half the effort!

Wire surface precipitation

So far there is no material to ensure that no precipitation, the specific performance of precipitation: surface whitening, oil or mist. With the current technology, this problem has not been solved. It is recommended that customers should choose the material with a slightly white surface, as this kind of precipitation will not affect its physical properties and electrical performance.

Do not use the material with oil on the surface, it is easy to produce shedding and peeling in use. In addition, the precipitation also has a light and heavy, good material its precipitation is slight, and in the short term is not easy to occur, even if the occurrence of a light wipe with the hand on the good.

Flame retardant TPE/TPU is a very unique material, TPE/TPU flame retardant problems still need to do more work in the selection of materials, formulations, processes. Tianswax micronized PTFE powder is added to the formulation of thermoplastics to play the role of flame retardant and anti-drip, helping thermoplastic materials to achieve higher standards of flame retardancy. Compared with conventional PTFE, it has excellent dispersibility and easy workability, no agglomeration at room temperature, no wrinkling in injection molded products, no crystalline spots in black and white products, and improves the glossiness of the product surface especially. Due to good compatibility, the impact strength is less affected in high impact formulation.

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