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What are the wire plastic particles used for

source:[Gravimetric blender]   release time:2021-04-30 16:35:08

Almost every cable factory uses plastic pellets, which are classified according to voltage levels: below 1KV, 10KV, 35KV, 110KV, etc., and there are also PVC, PE, EVA, etc. by material. In addition, there are more classifications required for flame retardant, low temperature, etc.
1) Polyvinyl chloride (PVC):

It is a very polar thermoplastic (plastic and thermosetting) amorphous polymer electrolyte, so it has good mechanical properties and large dielectric constant. The dielectric is usually 40.~4.6 at 20C and 1MHz. 47% halogen, flame retardant, combustible after formulating into plastic, density is 1.35g/cm cubic hard and soft density are different, good insulation performance, strong weather resistance, chemical resistance, shrinkage rate is quite low, generally 0.2~ 0.6%. The temperature resistance grades are 70C, 90C, 105C, CM, CMR, CMP. For PVC materials with a temperature resistance of 105C and above, crosslinking treatment should be carried out, which is to change the material from a linear linear structure through the radiation of the electron accelerator. It is a network structure, which improves its heat resistance stability and mechanical properties.

Mainly used for insulation and sheathing, because PVC has poor flow properties and is rarely used for injection molding.

2) Polyethylene (PE):

Divided into high-density polyethylene (HDPE: suitable for high-speed extrusion), medium-density polyethylene (MDPE, low-density polyethylene (LDPE: long-term use in power cables), linear low-density polyethylene (LLDPE), flammable, water absorption Small, low dielectric loss angle and dielectric constant. The non-foaming dielectric is usually 2.28~2.35 at 20C and 1MHz. The insulation performance is better than that of PVC. The filling is poor, and it is usually used for the insulation of communication cables or the sheath of power cables. Medium. Density 0.917~0.975g/cm3. In order to meet the needs, our country has already developed XLPE.

3) Polypropylene (PP):

The mechanical properties and electrical properties are very similar to PE, but the environmental stress resistance is better than PE. The disadvantage is that copper has a corrosive effect on PP, and the effect of tin plating is not very good. The density is 0.895g/cm3, and the dielectric constant is 2.55 at 20C and 1MHz.

4) Polyamide (PA):

Also known as nylon, it has abrasion resistance, oil resistance, high mechanical strength, good heat resistance, high melting temperature, and usually the temperature in the homogenization section reaches 300 C. It has strong water absorption, large dielectric constant, and poor insulation performance. It is usually at 20C and 1MHz. Generally, it is not used for insulation. Burning is a smell of burning animals. Its models are nylon 6, 9, 11, 12, 66, 610, 612, as well as nylon 1010 developed by our country. Nylon has three shortcomings in the manufacture of wire: 1) Anti-white, which is determined by the nature of PA. 2) The adhesion is poor, 3) the water absorption is large, it is easy to foam during the extrusion process, so the material should be preheated before the extrusion, the temperature is 80~105C.

5) Fluoroplastics
The fluoroplastic commonly used in industry is polytetrafluoroethylene (PTFE), but the most commonly used fluoroplastic for cables is polyperfluoroethylene propylene (FEP), and their density is between 2.08 and 2.20. In addition, commonly used fluoroplastics are ethylene-tetrafluoroethylene copolymer (ETFE) and polyvinylidene fluoride (PVDF). The density is between 1.70 and 1.75. The heat resistance grade is at least 200C and above, in addition, it also has very good cold resistance. Chemical resistance, low water absorption, dielectric constant of 2.6 at 20C and 1MHz. It is currently one of the two best plastics in terms of high temperature resistance (the other is silicone rubber cable). Usually used in high-speed communication cables, aerospace, radar, radiation resistant cables for nuclear reactors, cables for vehicles, etc., geological exploration cables, and logging cables.
However, the disadvantage is that the process is more difficult to process. When the wire is extruded, it is extruded without a mold, the corona resistance is poor, and the plastic has a corrosive effect on copper, so it must be tinned, and the price is higher.
6) Polyester

The main purpose of this material is not to make insulation or sheath. It is mainly used as a wrapper for the core in the process of manufacturing wires and cables. At the same time, it is often used with aluminum foil (coated on the aluminum foil) to form an aluminum-plastic composite tape. Polyester has good insulation properties.
7) Low-smoke halogen-free cable material (LSOH)

Low smoke refers to plastics with a light transmittance of >65% of the smoke produced by combustion, and some companies can even control it above 87%. Halogen-free refers to the production of 1gLOSH material at a high temperature of 935C for 30 minutes during the corrosive gas release test. The gas quality is within 2mg-5mg, if it is within the range of 5mg-15mg, we call it low halogen.

The popular LOSH materials are mainly PP, PE, EVA as the main materials, flame retardants Mg (OH) 2, AL (OH) 3, supplemented by SbO2 flame retardants, mainly to make it have a synergistic effect and reduce MgOH2 The amount of Mg (OH) 2 is large, and the compatibility, dispersibility, and impact resistance are poor, which is one of the main reasons for the poor mechanical properties of the LOSH material. Therefore, a coupling agent must be added to make the mixture tight Combine, improve its elongation and anti-length strength, commonly used coupling agents are silane coupling agents. At the same time, this plastic is non-PVC as the main material, and there is no need to add plasticizers, so LOSH has non-shifting properties, and at the same time, the thermal stability of LOSH materials is good, and there is no need to add stabilizers. In general PVC formulations, stabilizers and toners The 2 main enemies of environmental protection materials! Formulation example PP+EVA (VA content 20-30%) + Mg (OH) 2+ coupling agent + slip agent + elastic agent + other special additives FR LOSH material we often call thermoplastic low-smoke halogen-free flame-retardant polyolefin , Is an emerging environmentally friendly cable material.

Supplement: TPE is a thermoplastic elastomer, which is called differently in different regions. It is a general term for certain plastics. However, these materials have different densities and hygroscopicity. In the production, the raw materials must be dehumidified and dried, proportioned and uniformly mixed. This is often referred to as a dehumidifying dryer and gravimetric blender[Gravimetric blender]