EIWA CHEMICAL IND. CO.,LTD.

Rubber and plastic, when molded with air bubbles mixed in, are respectively called "rubber sponge" and "cellular plastic." These moldings are produced in the following methods:

（1）	Using blowing agent
（2）	Foaming by mechanical stirring
（3）	Utilizing gas by product of chemical reaction
（4）	Mixing/impregnating and vaporizing volatile solvent with low boiling point
（5）	Injecting liquefied gas
（6）	Mixing in micro-balloons(hollow)
（7）	Adding soluble substance and then dissolving it out

Among the above methods, only (1)"Using blowing agent" has a wide variety of applications for molding, from low-expansion foaming to high-expansion foaming. Blowing agents herein refer to chemicals (gas generating substances) that are mixed into rubber or plastic, are decomposed by heating to generate nitrogen gas, carbon dioxide gas, carbon monoxide gas, ammonium gas, or sometimes hydrogen gas etc. inside the base,and build up a cellular structure.

Blowing agents are roughly classified into two major categories: organic and inorganic.

With organic blowing agents, on the other hand, gas is generated at an appropriate rate by heating, and the temperature of decomposition can be easily controlled with blowing activators. As most of the agents generate nitrogen gas, a structure of micro closed calls is created. Thesedays, "blowing agent" is used to mean an organic blowing agent.

[Precautions in handling]

Do not bring near open flames or high-temperature objects;
Do not leave them in an open air or humid place;
Do not contact with skin. If an agent contacts skin, wash with soap;
Do not bring in contact with acid or water.

Precaution in handling blowing agents include:

Item	Type
Item	ADCA	DPT	OBSH
Specific gravity	1.65	1.55	1.53
Heat of decomposition Kcal/mol(cal/g)	10(86)	100(536)	55(123)
Specific heat cal/g℃	0.26	-	0.21
Heat of combustion Kcal/mol	256	873	1482
Acute toxicity*	9800 or more	80%DPT 2900 or more	5200 or more

※LD50, Median Lethal Dose (amount (mg/kg) killing half the rate with oral dosage)

ADCA (e.g. VINYFOR-AC-3) and DPT (e.g. CELLULAR-D) have high decomposition temperatures. This means that they do not decompose at some processing temperatures suitable for molding certain rubber and plastics. To resolve this problem, decomposition-accelerating activator are used to lower the decomposition temperature to approximately 120 to 180°C, when a blowing activator is used, the volume of gas generation may vary according to the type and/or amount of the assistant.
As decomposing activator for DPT, urea compounds (e.g. CELLPASTE-K5) have recently been used in many cases. As decomposing assistant for ADCA, on the other hand, inorganic salts including zinc oxide and tribasic lead sulfate, metallic soaps including zinc stearate and lead stearate, and urea compounds (e.g. CELLPASTE-101) are used in many cases.

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EIWA CHEMICAL IND. CO.,LTD.
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