Polyethylene low foaming film raw material

日期:2019/8/17 8:48:07 / 阅读: / 来源:本站

Polyethylene low foaming film raw material
1) Selection of resin. 1 variety selection, can be selected according to product performance and requirements. Softness, EVA → LDPE → HDPE. The packaging film for civil film and container lid gasket should be soft, and LDPE, EVA or a mixture thereof can be used; if vacuum molding, shallow tray, etc. have high rigidity requirements, HDPE should be used. 2 foaming process, HDPE, LDPE, EVA have their own characteristics, LDPE foaming process performance is good; HDPE foam is fine, but the inflation ratio is large, the bubble tube is easy to break; EVA cell is fine, but cooling is difficult; in LDPE Adding a small amount of EVA cells becomes finer. 3 resin and its melt flow rate, generally used MFRO.3 ~ 2.0g/10min for LDPE, MFR is too large, the foaming temperature is low, the processability is poor, and the foam is rough. The melt flow rate is suitable, the foam has fine pores, the surface is smooth, and the processability is good. HDPE is similar to LDPE, and a resin having MFR < 1 should be selected. The EVA melt temperature is low, and the resin having an MFR of 2 g/10 min has a good cell.
2) Selection of blowing agent. 1AC foaming agent is a general-purpose foaming agent, which has a large amount of gas and the decomposition product is colorless, odorless and non-toxic. Some people think that it has self-nucleation effect, the product cell is fine and uniform, and the storage stability is good, it is not easy to burn and explode, and it can be foamed in a wide temperature range. 2 foaming agent H, mostly used in the rubber industry, but the smell is heavy.
34,4 oxydiphenylsulfonyl hydrazide (OBSH), which has a foaming temperature of 120-140 ° C in plastic, is lower than AC foaming agent, and has uniform foaming pores. It is an ideal foaming agent for low foaming, but The price is high. 4 azobisisobutyronitrile (ABN), low foaming temperature, uniform cell, and low product density, suitable for processing low temperature EVA and MFR LDPE resin. The disadvantage is that the pores are thick, the decomposition residue is toxic, and the produced foam film is not suitable for packaging with food. 5 NaHCO3 foaming temperature is low and non-toxic. The product has long holes in the hole and a large amount of gas.
3) The foaming aid can accelerate the decomposition of the foaming agent and reduce the decomposition temperature of the foaming agent, which is also called an activator. Generally, it is a compound of zinc, bismuth, cadmium, aluminum, a fatty acid metal salt, an organic acid, urea, and the like. Generally, ZnO, ZnS, BaSt, CaSt, or the like is used.
4) Nucleating agent, the foaming hole of the AC foaming agent without the nucleating agent itself is fine. The talc powder can be added as a nucleating agent by using the ABN foaming agent, and silica, sodium benzoate citrate or the like can be used.
5) Lubricant, when mixed by dry mixing process, mix some white oil in the resin particles.
6) Crosslinking agents, such as cumene peroxide (DCP), make the resin properly crosslinked, which is beneficial to gas encapsulation. If the melt flow rate modifier silicone oil is added at the same time, the viscosity of the melt is lowered in the processing temperature range. The viscosity and viscoelasticity are suitable to facilitate the diffusion of the decomposition gas in the melt and the melt encapsulation of the gas. Silicone oil and DCP are synergistically adjusted for better results.


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