Physical Foaming Nucleating Agent is specially designed for easy incorporation into insulation raw material compound for processing Physical Foaming Insulated RG series coaxial cables. The compound consists of base resin and more than 4 kinds of other supporting agents such as Stabilizer, Activator, foamable antioxidant and expander. When used correctly, it allows the formation of small, uniformly distributed cells.
While the exact temperature profile required will depend upon the screw design and construction being made, the following extrusion temperature profile represents a good starting point:
Feed Zone : 140 ℃to 150 ℃
Transition Zone : 170 ℃to 180 ℃
Gas injection point : 170℃ to 190 ℃
Metering Zone : 140℃ to 170 ℃ (depending on insulation diameter)
Crosshead and die : 130℃ to 190 ℃ (depending on insulation diameter)
Polyolefin is a general plastic with incomplete crystallization. Its crystallization behavior, such as crystallinity, crystallization speed, crystal morphology and spherulite size, directly affect the processing and application properties of products. Polyolefin nucleating agent is a new functional plastic additive, which can promote the crystallization of resin, change the crystallization behavior and morphology of resin, and refine the spherulite size.
By changing the crystallization behavior of polyolefin resin, increasing the crystallization speed and crystallinity, the transparency, rigidity, surface luster, impact strength, hot deformation temperature and shortening the molding cycle of the products can be improved, and the processing and application properties of the final products can be improved. With the acceleration of the engineering process of general plastics, the requirements for processing and application performance of polyolefin products in the application field are higher and higher.
The use of nucleating agent for crystallization modification has become an important way of polyolefin physical modification in the world. Since the 1990s, the production and consumption of nucleating agents have been increasing rapidly, ranking first in the annual average growth rate of all kinds of plastic additives. In 2005, the global consumption of various polyolefin nucleating agents reached 10000 tons. According to the modification effect of nucleating agent, it can be divided into four general types: general type, enhanced type, transparent type and β nucleating agent: ① inorganic nucleating agent, such as talcum powder, various silica gel, kaolin, – ship has weak nucleation; ② – or binary fatty acid and aralkyl acid salts, such as sodium succinate, sodium glutarate, sodium hexanoate, aluminum phenylacetate, have medium nucleation activity; ③ Alkali metal salts or aluminum salts of aromatic or alicyclic carboxylic acids such as aluminum benzoate, sodium benzoate or potassium are active nucleators.
The main transparent agents are dibenzylidene sorbitol and its derivatives. The enhanced nucleating agents are mainly organic phosphates, including phosphate metal salts, phosphate basic metal salts and their complexes. There are two main types of β nucleators, one is a few fused ring compounds with quasi planar structure, the other is composed of some dicarboxylic acids and oxides, hydroxides and salts of group IA metals in periodic table.However, 80% of the current consumption is dibenzylidene sorbitol (DBS) nucleating agent.
