Daiwa Chemical Industries Co., Ltd.
Prethermo C series, comfortable temperature maintaining agents

Temperature control by alternation of heat absorption and release Suitable for garments, bedding and work clothes

(Interview by textileinfo editorial)

Temperature control within boundaries around 25°C
Suitable uses are in underwear, shirts and bedding

S. Nakamura, general manager of the R&D Dept.

T. Hariu, chief of the Business Dept.

Nakamura:

Prethermo C-25 has been developed based on the principle of the absorption and release of latent heat (at the solidifying/melting point). In layman's terms, while water turns into ice at 0°C, higher aliphatic hydrocarbon contained in Prethermo C-25 solidifies and melts at 25°C, and in Prethermo C-31 at 31°C. We have two other items, too, that concern different temperature ranges available for use in non-fiber fields.

Q:	Why 25°C and 31°C?

Hariu:

25°C is the average air temperature in Japan and also the temperature at which humans feel comfortable. As for 31°C, this temperature setting has been chosen because it would provide coolness being a little lower than that of the surface of the skin of around 33°C.

Q:	So they can be used according to temperature requirements.

H:	That's right. For example, when the temperature of a bedroom stays above 25°C on a hot summer's night, the use of bed linen treated with Prethermo C-31, and not Prethermo C-25, will bring about a comfortable sleeping environment.

Q:	When you work under the scorching sun wearing a Prethermo C-25 shirt, it will not stay cool after Prethermo C-25 melts. What happens then?

H:

Prethermo C-25 melts and solidifies around 25°C, but the temperature then does not rise or fall dramatically. The rate of change becomes slower. Fig. 1 Temperature changes in Prethermo C-25 and Prethermo C-31 s (click to enlarge) Look at Fig. 1. It shows measurements of temperature changes in Prethermo C-25 and Prethermo C-31. From these, we know Prethermo C-25 has the function of maintaining a certain temperature range around 25°C despite changes in the air temperature, and Prethermo C-31 around 31°C. Entering a very cool, air-conditioned room from the heat of outdoors will not give you chills if you are wearing a Prethermo C-25 shirt. The shirt will cool down slowly. The temperature won't rapidly go back up, either, when you go out into the heat again. It will rise as you remain outdoors and Prethermo C-25 will eventually melt. Then, heat makes you sweat. The shirt cools down as heat is released when sweat evaporates. Prethermo C-25 stores that heat, preventing the temperature from rising. It maintains a constant temperature because heat is consumed in the melting and solidifying of Prethermo C-25.

Heat storage and release lasts semi-permanently in Prethermo C-25

H:

The answer is shown in Fig. 2. Because of latent heat around 25°C, the temperature drop becomes slower on fabric treated with Prethermo C-25 compared to that which is untreated, with more time taken in reaching the ambient temperature. Fig. 2 Temperature changes on fabric surface treated with Prethermo C-25 (click to view)

Q:	How long is the latent heat mechanism valid for in Prethermo C-25?

N:

It lasts semi-permanently, as long as Prethermo C-25 remains in the treated fabric. The theory of latent heat has long been pretty well known and is often used in air-conditioning of airports and in the electrical field. Commercialization of a chemical product based on this theory was difficult. We have succeeded by micro-encapsulating the agent, in smaller dimensions than fiber. If the comfortable temperature maintaining agent was applied to fiber as it is, it would be washed out through laundering. Moreover, its physical characteristics may alter as it is unstable both chemically and physically. That is why micro-encapsulation was used in Prethermo C series, the 'comfortable temperature maintaining' finishing agents.

Q:	How resistant is Prethermo C-25 to washing?

N:

Look at Fig. 3. It shows fabric treated with Prethermo C-25. Because Prethermo C-25 is micro-encapsulated in dimensions smaller than fiber, it penetrates into fiber and firmly adheres to it with a binder (Ficoat). It is very difficult to wash it out through laundering. Fig. 3 Adhesion of Prethermo C-25 to fabric (click to view)

Q:	The micro-capsules are not breakable by mangle squeezing?

N:

The micro-capsules of Prethermo C-25 series would not be broken by mangle squeezing because they are smaller than fiber and fiber is bigger than the capsules. There would be no oily stains resulting from the breakage of micro-capsules during laundering nor any flowing out of comfortable temperature maintaining properties.

Prethermo C-25 applicable to all fiber but silk

H:	Anything but silk. However, with wool, the effect of Prethermo C-25 or C-31 might not be very distinct as wool itself has thermal properties.

Q:	What kind of products is it good for?

H:

Shirts, blouses, underwear and bedding such as bed linen and futon, as well as work clothes. In particular, treatment with Prethermo C-25 will be effective in dimension-stabilized shirts as they tend to have less breathability. But we are also looking forward to hearing ideas that our customers might have for further exploitation of the latent heat mechanism in Prethermo C-25 and Prethermo C-31.

Q:	Would Prethermo C-25 not cause skin irritation when used in shirts and underwear worn directly on the skin?

Favorable results obtained in skin irritation test

Q:	What about its formalin content that would be called into question for use in underwear?

N:	It is less than 75ppm when used in textile finishing. The figure has not proved problematic.

Q:	What facilities are required for Prethermo C-25.

H:	Padding equipment. Consult us to see the compatibility of facilities as padding equipment varies. Let me once again go through the details of Prethermo C-25.

Details of Prethermo C-25

>>Description

>>Features

>>Directions for use

>>Handling instructions

• Shake well before use.

• Make sure the container is hermetically sealed for storing.

• Verify compatibility beforehand in cases of simultaneous use with other products by conducting preliminary tests.

• Verify color alteration before use in dyed fabric by conducting preliminary tests. Preliminary tests are also necessary with regard to fastness.

• The reference above is based on tests conducted with utmost care, however, it does not provide a full guarantee for practical use. Through preliminary testing is required before use.

>>Packaging