Silica gel products in the forming, if the vulcanization temperature is increased, the vulcanization time can be shortened, the vulcanization efficiency will be effectively improved, so many Dongguan silica gel products factory vulcanization molding practitioners in the early stage in order to speed up the molding speed of silica gel, rubber products, will start on the increase in temperature. Sometimes it is really effective to shorten the curing time, but sometimes it will be self-defeating, not only did not improve the capacity, but also a lot of numbness and rupture, what is this?
In fact, silicone, rubber vulcanization temperature cannot indefinitely increasing, because of the silicone and rubber is a polymer, high temperature can cause the rubber chain output cracking reaction, crosslinking rupture, resulting in "sulfide to return the original" phenomenon, resulting in a decline in the physical and mechanical properties of the silicone, rubber products, namely we often say change and burst. ES According to the experience accumulated in the production process of some silica gel products, the common silicone and rubber vulcanization temperature recommendations are as follows:
Natural rubber (NR) vulcanization temperature recommended: the most reasonable range :140~150℃, not more than 160°C;
Recommended curing temperature of butadiene rubber (BR), isoprene rubber (IR) and neoprene rubber (CR) : the most reasonable range :150~160℃, not more than 170C;
Styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) curing temperature suggested: curing temperature can be used more than 150℃, but not more than 190℃;
Recommended curing temperature of butyl rubber (IR), EPDM: the most reasonable range of 160~180℃, not more than 20O°C;
Hot vulcanized silica gel [SR], fluorine rubber (FR) vulcanization temperature recommendation: the most reasonable range of 170~180℃, if the need for secondary vulcanization, the secondary vulcanization temperature control in 200~230℃, time according to the process requirements within 4~24H.
Vulcanization of rubber products three elements: temperature, time, pressure. When the pressure is certain, the high temperature curing time is short, on the contrary, the low temperature curing time is longer. Rubber polymer, in the state of high temperature will make the molecular chain damage, leading to cross-linking bond fracture, that is, the phenomenon of "vulcanization back to the original". After the vulcanization temperature is determined, the pressure and time will be determined because the equipment and abrasive tools are existing in the enterprise.
Vulcanization temperature selection generally considered raw gum varieties and vulcanization system selection to consider:
The vulcanization temperature range of ordinary sulfur vulcanization system is 130~158°C;
Effective and semi-effective curing system curing temperature range 160~165℃;
The temperature of the resin or peroxide vulcanization system is between 170 ° C and 180° C.
Thick products or line products choose low temperature long time vulcanization, thin products high temperature rapid vulcanization.
Hard products choose low temperature vulcanization, slow down the speed of reaction heat generation, contribute to heat dissipation, so that the product internal temperature is reduced to meet the vulcanization is not easy to burst.
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