EPP is the abbreviation of expanded polypropylene, which is the abbreviation of a new type of foam plastic. EPP is a polypropylene plastic foam material, a high-crystalline polymer/gas composite material with excellent performance. With its unique and superior performance, it has become the fastest growing new environmentally friendly pressure-resistant buffer insulation material. EPP is also an environmentally friendly material that can be recycled and reused, can be naturally degraded, and will not cause white pollution.

Performance and Uses

EPP has light specific gravity, good elasticity, shock and compression resistance, high deformation recovery rate, good absorption performance, oil resistance, acid resistance, alkali resistance, resistance to various chemical solvents, non-absorbent, insulation, heat resistance (-40 ~ 130 ¡æ), non-toxic and tasteless, 100% recyclable and with almost no performance reduction, it is a truly environmentally friendly foam plastic. EPP beads can be molded into various shapes of EPP products in the mold of the molding machine.

EPP is widely used in automobiles, such as bumper core materials, anti-collision blocks, ceiling linings, door fillings, headrests, sun visors, etc., which can save fuel consumption and improve the safety factor of passengers.

EPP has been widely used in the packaging industry, such as electronic products, medical devices, etc., especially in the packaging of export products, and has become an irreplaceable packaging material in response to environmental protection requirements. Due to its non-toxicity and high temperature resistance, it is also widely used in food packaging and microwave heating.

Market demand

EPP has developed rapidly in the past decade since its introduction. The world market was 70,000 tons in 1999 and more than 200,000 tons in 2008. China's consumption in 2008 was 25,000 tons, but due to its high production technology difficulty, only a few large companies in a few countries can produce it. The EPP market in China is completely monopolized by Japan's JSP and Kaneka companies. They have factories in Suzhou and Wuxi. The price per ton (excluding tax) is 40,000 to 60,000 yuan. The high price limits its wide application.

Production method

(I) In-kettle impregnation method

Put the PP beads into the kettle and soak them with butane at a certain temperature and pressure, and then suddenly reduce the temperature and pressure to make them expand and foam. This method sounds simple but is actually quite complicated. Currently, only Japanese companies have mastered it. It is said that the investment is huge and the technology will not be transferred. Japan's JSP and Kaneka companies have factories in Wuxi and Suzhou, and they are very secretive. The PP beads used in the in-kettle impregnation method are generally produced by the strand cooling method, which has low output and is troublesome.

(II) Extrusion method (Germany)

Put high melt strength PP and compound into the extruder, add foaming agent (such as butane) after melting, make it fully dispersed and evenly dispersed, and then extrude it from the die hole after cooling. Due to the sudden pressure reduction, it foams and is cut into small beads in time, and then quenched to shape. Three years ago, Chengdu Pujiang City imported Bersti ROF Company spent 10 million yuan on a production line of beads with an output of 80 kg/hour, but the test run has not been successful so far.

Production principle

Generally, EPP beads must first be pressurized in a pressure tank (that is, the beads are filled with air at a certain pressure), and then compressed air is injected into the mold of the EPP molding machine through a spray gun, and steam is introduced to make the EPP beads further expand and the surfaces are welded together to form. After cooling, the mold is stabilized at a certain temperature to obtain the EPP product.

Raw materials

What is used is not ordinary polypropylene (PP), but high melt strength polypropylene (HMS-PP).

Generally, the molecules of PP are plain (that is, without branches) and must undergo certain post-treatment to make their molecules branched, commonly known as PP grafting (general grafting will degrade and fail to achieve the purpose of making it have high viscosity and high melt strength). It is currently known that Borealis and Basell can produce HMS-PP.

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