Why is rubber products whitening?
In our life, many people must have seen the use of rubber products for some time after the phenomenon will be white, such as in the case of large humidity, the paint is easy to white.
Rubber has unvulcanized rubber (hereinafter referred to as rubber) and vulcanized rubber (hereinafter referred to as the product) of the points, rubber spray cream on the appearance of the package and the appearance of the product blowing cream. Blooming (bloom) is a liquid or solid compounding agent from the rubber to the appearance of the appearance of the rubber . Visible rubber internal ingredients with the separation, it constitutes a spray cream. The way of rubber blowing cream summed up, generally divided into three. That is, powder, spray wax, fuel injection (also known as exudation).
Dusting is a vulcanizing agent, accelerator, active agent, antioxidant, filler and other powder compound agent in the rubber appearance, and constitute a layer of powder.
Spray wax is white wax, wax and other waxes in the rubber surface, and constitute a layer of wax film.
Fuel injection is softener, tackifier, lubricant, plasticizer and other liquid compounding agent in the rubber appearance, and constitute a layer of oil. In practice, the appearance of the rubber spray is sometimes presented in a way, sometimes in two or three ways.
(1) Recipe planning is not appropriate:
Full discharge: common in sulfur, accelerators, active agents, antioxidant relocation spray: common in processing aids, relocation of antioxidants. Antistatic agent generation spray: common in the sulfur vulcanization system accelerator and react with the reaction products to stop: common in organic peroxide curing system of low molecular weight material stress discharge: common in inorganic fillers: such as calcium carbonate.
(2) technical operation is not appropriate:
Uneven kneading constitutes a lax bad, part beyond the fullness
The glue temperature is too high, so that the mixing agent part of the excessive
Weighing is not accurate (multi-called, less known, missing, wrong)
The vulcanization temperature is too high and the polymer degrades
The vulcanization temperature is too low, constitute the reaction is not complete and the occurrence of sulfur thawing vulcanization at all times, constitute the sulfur sprinkler spray release agent or mold water operation is not correct, constitute the appearance of rubber white appearance
(3) the quality of raw materials due to the origin of raw materials is not the same, the system is not the same, the technology is not the same, the bulk is not the same as the raw materials are very different, raw rubber composition technology: polymerization temperature, catalyst, monomer composition, Solubility is different. Purity, moisture, ash, pH, physical properties such as seizures change
(4) Storage conditions Poor temperature: The solubility of the compounding agent in the rubber is usually followed by the rise and fall of the temperature (pressure and humidity): the pressure of the rubber storage, the ambient air humidity and the time to the solubility of the compound Influence, usually little effect. However, if the pressure is large, the pressure in the rubber parts of the compound will constitute the nucleus, separated from the rubber appearance, constitute a spray cream; if the air humidity is too large, rubber, Non-polar effect) weakened, the solubility of the compound decreases, and then cause the frost; the longer the storage time, the more obvious the appearance of the rubber spray, because the storage environment in the air temperature and humidity changes along the season and not the same, and not the same Larger, it is easy to form the solubility of the compounding agent to change, and then cause the spray cream.
(5) rubber aging
The aging of the rubber causes most of the vulcanized rubber to make a well-balanced network of structural damage, and then also damage the rubber system with a variety of ingredients and raw rubber molecules and the chemical or physical contact between the reduction of the compound in the rubber Solubility within the system. Thus, those parts in the over-full state of the mixture will be separated from the rubber free to form a spray cream.