As temperatures rise, many in Japan start reusing heatstroke prevention items called "neck coolers" or "cool neck rings" that have been stored in drawers or other places. While these cooling items are essential for the heat, users should be cautious of potential liquid leakage due to deterioration, which can cause skin issues like rashes.
Leaking liquid deformed vinyl tablecloth
Erika Miyajima, 42, from Tokyo, shared her experience on social media with a photo of a vinyl tablecloth that had been deformed by a leak from a neck cooler. She bought the cooling item from a local supermarket last summer and used it regularly for outdoor activities, storing it in the fridge during the off-season.
Marks left by a leaking neck cooler are seen left on a vinyl tablecloth.
On April 19 this year, when the temperature in Tokyo exceeded the 25℃ mark, she took the neck cooler out for the first time in a while. After putting it on her 10-year-old child for about 30 minutes, she left it on a vinyl tablecloth overnight. The next morning, she found that the area where the neck cooler had been placed was deformed. Upon touching the tube, she realized it was slimy and leaking liquid.
"I didn't notice the leakage due to condensation when I took it out of the fridge. I don't think my child would notice because they are so engrossed in their play," Miyajima told the Mainichi Shimbun. She checked another neck ring, purchased last summer and stored at room temperature, and found it was leaking as well.
What is the liquid in the tube?
Reports of incidents related to neck coolers, such as liquid leakage causing redness on the neck and content sticking and leading to dermatitis, have also been found in the "accident information data bank," an online database on accidents and consultations by the Consumer Affairs Agency and the National Consumer Affairs Center of Japan.
Ring-shaped neck coolers use a "phase change material" (PCM), which alternates between liquid and solid states depending on the surrounding temperature. As it melts from solid to liquid, it absorbs heat, so when worn around the neck, it feels cool and provides a cooling effect for a certain period of time.
According to the "chemical product PL consultation center," which provides consultation on accidents and complaints caused by chemical products, PCM is primarily made from a type of saturated hydrocarbons known as "normal alkanes," which have varying melting points based on the carbon number. The neck coolers in use have a melting point around 26℃ -- higher than water.
A representative of the consultation center said, "Saturated hydrocarbons are also called 'paraffins' and are similar to the ingredients used in candles and other products." They called for caution, saying, "Liquid paraffin is essentially 'oil,' and if leaked, it could alter the resin in some types of tablecloths, or cause a rash if left on the skin."
A neck cooling ring
Another thing to keep in mind is that if there is a leak, it is important to avoid open flames.
Detecting and handling leaks
How can we tell if a neck cooler is leaking? According to a representative from Genki Labo, a company that plans and sells daily goods, signs of leakage include unnatural dents or deformation, oily liquid seeping out, sticky residue on hands and significantly reduced cooling effect after freezing. For products stored long-term during the off-season, it's advisable to return them to liquid form in a warm place, check the surface condition and inspect for leaks before reuse.
If a neck cooler is worn without noticing leakage, another manufacturer's representative advises washing off any of its content from skin or hair immediately with soap and running water. If skin abnormalities occur, consulting a doctor is recommended.
If not used for an extended period, neck coolers do not need to be stored in a refrigerator or freezer. Instead, they should be kept in bags to prevent deformation of the polyurethane surface and be stored at room temperature out of direct sunlight or in a cool, dark place with a stable temperature.
