Cross-linked polypropylene foam technology is widely used

With the increase of processing temperature, the melt viscosity of PP resin decreases sharply, and the gas decomposed from the foaming agent is difficult to maintain in the resin. The escape of gas will cause the foaming to be difficult to control; more heat will be released during crystallization, so that the Since the melt strength is reduced and the bubbles are easily broken after foaming, it is difficult to obtain a foam having a high closed cell ratio. If the PP resin can be cross-linked before foaming, the melt viscosity will decrease as the temperature increases, and the rate of decrease will be slower.涣 箍 箍 箍 箍 岣 岣 岣 岣 岣 P P P P P P P 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣 岣. Tensile strength, rigidity and impact strength have also been greatly improved, and oil resistance and wear resistance have also been greatly improved.

Cross-linked foaming PP technology can be divided into two-step method and one-step method. In the two-step method, PP, cross-linking agent, foaming agent and other auxiliary agents are firstly blended and extruded, and then water bath or radiation crosslinking is performed, and then the temperature is raised to obtain a foamed plastic. The one-step method is to blend PP, cross-linking agent, foaming agent and other auxiliary materials into a suitable direct cross-linking during the extrusion process and decompose the foaming agent to produce a foamed plastic. However, this method requires accurate control of the degree of reaction in the extrusion process and is therefore more difficult. At present, a number of companies and research institutes are studying or have already researched the production process of cross-linked foamed PP. Most of these are two-step production processes, and a few can be continuously extruded in one step.

The British company Dote introduced a micro-crosslinked thermoformed PP foam under the trademark Yropazote. The product is produced in a two-stage process by first extruding a small foamed piece 3 mm thick and then cross-linking it with peroxide or cross-linking with radiation, then cutting it to a certain degree of twist, and then Placed in an autoclave (pressure up to 69 MPa) and subjected to heat and pressure, while allowing N2 to dissolve in it for a certain period of time, the sheet was moved to a low pressure autoclave to allow the gas to escape from the system, at which time the sheet expanded. To about 22 times the original, which has a closed-cell structure of 10%, a density of 0.3g/cm2

The Institute of Yangzi Petrochemical Company adopts organic peroxide cross-linking agent, polypropylene and polyethylene composition for micro-crosslinking in the process of mixing and extrusion. The material can be used for thermoforming, processing various products, used in automobiles, household appliances, etc. The furniture and buildings were received.

Sinopec Beijing Research Institute of Chemical Industry Researched Low Irradiation Dose Radiation Crosslinking to Produce Foamed PP

Material and product technology and apply for a patent, foaming rate of 8 to 25. A suitable melt flow index PP raw material is mixed and granulated with various additives, and then tableted, irradiated and crosslinked, and finally foamed in an oven to obtain a foamed PP sheet.

Ruishi Alveo has also been producing radiation-crosslinked PP/PE foams for several years in the automotive industry.

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