[IP Encyclopedia] ‘Hand warmer’ intellectual property that gives warmth with full of two hands in the cold weather

Disposable solid hand warmer [Photo Provided : Wikipedia]

Patent Application : Hand warmer (EP1611400B1)

Year : 2003

Country : U.S.A

Region : Dalton Georgia State

Name : Daniel H. Yim (Currently Kobayashi Healthcare Inc)

“My hands are freezing! My feet are freezing!”

Hands and foot are vulnerable to winter wind. There are useless cases even when you put on gloves because especially hands are frequently used and exposed to outside rather than foot which put sneakers and socks on. Hand warmer’ is specifically invented for hand in the winter season. Now in the IP encyclopedia let’s take a look at the intellectual property the various form of ‘Hand warmer’ invented by hand for hand.

Hands are very important part of the body. It might be the most useful and practical part in the body. Due to the reason it feels high fatigue and should be protected from winter cold. Human being who knows importance of hands made a cold weather gear.


Nowaday’s disposable hand warmer so called ‘hot pack’ has short history which the patent was discovered at 2000s. Actually hand warmer has existed in the various form of history. The purposes of maintaining the hand’s warm temperature in the cold winter are same but it has various form following way of giving off heat.

The first patent application of hand warmer came from Jonathan alice in the 1891 New Jersey United States. It is accounted for the gear that cover the hands and foot but only patent is registered not mass produced. Hand warmer that was sold at the public was mass produced first time and developed by japanese.


In the first 1920s. Niichi Matova had a success about experiment that give off the heat by generating oxidation reaction with vaporized white gasoline so-called zippo oil by using platinum as catalyst. After that time in order to make a practical hand warmer they studied and finally had a success for inventing a prototype of product so called ‘Hakukin-kairo’ in the 1923. After the period it was late time but finally registered U.S.A patent in the 1964.

It was also used at U.S.A and Europe beyond japan due to high performance. Of course it had many weakness. It had to fill up the oil in advance and preheat and also it gives off the heat slowly according to their type from 10 and 30 hours. Moreover it could make a dizziness by slowly coming up oil smell and it is difficult to put out and regulate the fire power once it is ignited.


After that time liquid form of hand warmer was invented in 1976 U.S.A. That is the ‘Snap button hand warmer’. The tube has soft liquid not water and it is a thin round chip like a size of a small coin inside.

The principle of liquid hand warmer is used by solidification of Sodium acetate. The clear liquid in the tube is supersaturated with sodium acetate. Sodium acetate is an unstable substance and has the characteristic of hardening easily even with a slight impact. When a round chip with a liquid is ticked and bent and then removed the liquid in the tube turns into a solid due to the impact. At the same time the heat absorbed in the liquid state is expelled instantly and this exothermic effect acts as a hand warmer.

It was famous for interesting and soft substance but it generates bad smell from chemical reaction so it is hardly used. If so how was the hand warmer developed that it is used at nowadays?


Solid hand warmer was launched through U.S.A patent in 2003 at first time. The principle of hand warmer has a secret which is powder inside the pocket. The inside of the pouch contains iron powder salt and activated carbon. The moment when the hand warmer wrapper is opened and rubbed the iron powder get exposed to oxygen and occurs oxidation. Salt and activated carbon which act as catalysts play a role in causing this oxidation to occur stronger and faster.

Therefore a solid hand heater can generate heat close to 60 degrees within few minutes after opening. Although it varies depending on the product it has the advantage of maintaining a temperature of 60 to 70 degrees for about 10 hours. It has a disadvantages in that it is ‘disposable material’ but it is frequently used and practical because it has long holding time at high temperature rather than liquid hand warmer.


In korea solid hand warmer came out in the military services where it is inevitable to work outdoor in the cold weather. In the PX which is convenience store at military disposable hand warmer was sold and it is necessity for soldier when they are trained outdoor in the cold weather. It is also useful for outdoor on duty. The disposable hand warmer which is famous for military became a most famous cold weather gear in the winter season.

As New Years Day goes by it seems the cold weather is slowly disappeared. However due to the temperature difference between day and night the outdoor circumstances is not safe from cold weather in the night. Let’s melt the short period cold by using the disposable solid hand warmer that gives convenient and warm temperature.

First patent of hand warmer [Photo Provided : Google patents]

Hand warmer Hakukin-Kairos patent [Photo Provided : Google patents]

Liquid shape of hand warmer [Photo Provided : Wikipedia]

Patent of disposable solid hand warmer [Google patents]

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