Why do rubber products go white?

- Jan 09, 2020-

In the life, a lot of people have certainly also seen the phenomenon that the meeting after rubber product USES period of time appears to send white, for example below humidity is bigger circumstance, paint is easy to send white.

Spray frost

Rubber has not vulcanized rubber (hereinafter referred to as rubber) and vulcanized rubber (hereinafter referred to as products), rubber spray cream includes rubber surface spray cream and product surface spray cream.

Bloom is the appearance of a liquid or solid complex moving from the inside of the rubber to the outside of the rubber [1].

Can be seen that the rubber internal coordination agent separated, formed a spray of frost.

To the way that rubber gush frost is summed up, divide into 3 kinds roughly.

Namely spray powder, spray wax, spray oil (also known as exudate).

Powder spraying is vulcanizing agent, accelerant, active agent, antiaging agent, filler and other powder additives separated in the rubber appearance, and constitute a layer of powder.

Spray wax is wax, wax and other wax separated in the rubber appearance, and form a layer of wax film.

Oil injection is softener, viscosifier, lubricant, plasticizer and other liquid additives separated in the rubber appearance, and constitute a layer of oil.

In practice, the appearance of the rubber spray is sometimes presented in one way, sometimes in two or three ways together.

(1) improper formula planning:

Full spurt: common in sulfur, accelerant, active agent, antiaging agent relocation spurt: common in processing AIDS, moving antiaging agent.

Antistatic agent generation spurt: common in sulfur curing system accelerant and reaction products reaction stay: common in organic peroxide curing system low molecular material excessive stress spurt: common in inorganic fillers: such as calcium carbonate.

(2) improper technical operation:

Mixing and mixing is not equal to form slack, part of the excess

The mixing temperature is too high, so that the mixture is partly excessive

Inaccurate weighing (more, less, missing, wrong)

Curing temperature is too high, polymer degradation to form spray

Vulcanization temperature is too low, the formation of response is not complete and attack of the sulfur spray frost vulcanization time is not good, the formation of sulfur spray frost spray demoulding agent or washing water operation is not appropriate, the appearance of rubber white appearance

(3) raw material quality changes due to different raw materials, different manufacturing methods, different technologies, different batches of raw materials are very different, raw material composition technology: polymerization temperature, catalyst, monomer composition of the difference, resulting in different solubility.

Changes in purity, moisture, ash, pH and physical properties

(4) poor storage conditions: temperature: the solubility of the compound in the rubber usually follows the rise and fall of the temperature and the rise and fall time (pressure and humidity) : the pressure, the humidity of the surrounding air and the time of the rubber storage also have an impact on the solubility of the compound, usually the impact is not big.

However, if the pressure is greater, the rubber in the compression part of the compound will form a crystal core, from the rubber appearance, a spray of frost;

If the humidity of the air is too large, rubber in the polarity of the compound on the rubber (non-polar) effect weakened, the solubility of the compound decreased, and then lead to frost;

The longer the storage time, the more significant the rubber appearance spray frost, because the temperature and humidity of the air in the storage environment with the change of season and not the same, and not as big, it is easy to form the solubility of the mixture attack change, and then cause the spray frost.

(5) rubber aging

Rubber aging mostly causes damage to the intact and balanced network structure of vulcanized rubber, and then damages the chemical or physical relationship between the various compounding agents and raw rubber molecules and the compounding agents in the rubber system, reducing the solubility of the compounding agents in the rubber system.

As a result, those parts are too full condition of the compound will be free from the rubber, forming a spray of frost.