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Manufacturing method of foam rubber

at the time of production of rubber sponge products, typically begins with a rubber compound molded or extruded pieces, strips and other shapes of the sponge, and then cut into the needs of rubber products. There are three types of processing methods: continuous pressure molding, high-pressure molding and extrusion.

1. atmospheric pressure mould: mould under normal pressure of sponge rubber, is sufficient foam rubber material inside the mold, then curing foam. Note compounds do not fill the mold cavity, leave some space for the foam rubber compound expansion. to open vents above the cavity so that rubber expansion mould cavity above the air out. Before adding rubber materials, mat first cavity wall a piece of cloth or a layer of talcum powder, curing rubber material in the lower part the escaping gas can be discharged. Atmospheric pressure molded foam rubber is required when viscosity is low, and the rubber compound liquid in the cavity, susceptible to bloat. This method of sponge rubber foam structure for open-cell structure, may also be closed-cell structure, depending on the variety and amount of foaming agent and vulcanization of rubber speed.

2. high pressure mould: high pressure moulding foam rubber is generally divided into pre-sulfide and sulfide phases completed. (1) dry rubber molding vulcanization vulcanization stage like a traditional, containing foam rubber filled cavity, mold after 135 ~: L45 ° c under pressure precured 25 ~ 35min, and pressure relief. Because the cavity is filled rubber compound, after the mold cavity is closed as the curing progresses, increasing amount of gases produced from the decomposition of blowing agent, makes pressure increase within the bubble. Discharge pressure, due to the external pressure lifted, inside a bubble of high-pressure air bubbles quickly, without fully crosslinked compound expansion, resulting in tiny closed-cell foam. Rubber foam expansion ratio through formulation, and adjust the time and temperature control. Of final product dimensions and compound when fully cured at the end of the second stage of curing is complete.

it must be noted that opening pressure must be fast, smooth and completely; to design the mold cavity wall into 15-degree angles, products release; pressure platen press activities of the various components it is necessary to smooth, the rubber compound completely free expansion. If the compound was hampered during the expansion process, products may distort or crack. (2) the final curing stage pre-Vulcanized sponge semi-finished products into the oven or within a larger mold, in conditions of higher curing temperature 15 ~ 25t devulcanization 6O ~ the 90min, sponge products fully cured and expansion, up to final size. Final curing temperature and time is determined by the thickness of the product.

need to be aware of is that sponge sole expansion to its final size of the completion of the first phase, while the second stage is molded foam soles in 100-121 ° c heat 10 ~ 24h, stable size. If unstable, use products excessively when your product can transform.

3. continuous extrusion processing: the method is rubber industrial in the preparation sponge products most effective, and most economic of processing method, is will contains sent bubble agent of rubber material through extrusion machine extrusion or with calender pressure into must thickness of film, then will extrusion semi-finished products or pressure extended film continuous through hot air furnace or liquid sulfide media, and microwave, and boiling bed, continuous sulfide equipment sent bubble, and stereotypes. These continuous vulcanization process carried out at atmospheric pressure or high temperature, blowing agent decomposes quickly, to make the adhesive foam, rubber vulcanization speed requirements soon, formulation choice when fast-curing adhesive and curing systems.

extrude closed cellular material for automobile sealing strip, building gaskets, pipe insulation and so on. EPDM, CR, SBR, NBR rubber and their blends, this method can be used manufacture co. Because of pipe insulation requirements fire, so NBR/PVC blend foam is used the most.