Incorporating “Phase Change Gels” into Flexible Foams for Improved Thermal Comfort

Title: Thermal Storage Gelatinous Triblock Copolymer Elastomer Particles in Polyurethane Flexible Foams

 Number/Link: US2013/295371

Applicant/Assignee: PETERSON CHEMICAL TECHNOLOGY

Publication date: 07-11-2013

Gist”:  Particles of  “phase change gels” prepared from plasticized styrenic TPEs and conventional PCMs are incorporated into polyurethane or latex flexible foams

Why it is interesting: A conventional phase change material (PCM) selected from alkanes, PEGs, hydrated salts ect. with a transition temperature between 20 and 35°C is melt-blended with a plasticized styrenic triblock copolymer like SBS, SIS, SEBS etc. to form a “phase change gel”. The gel is then comminuted and added to a flexible foam forming composition in an amount of about 30 pphp. The resulting foams have an increased thermal conductivity which together with the temperature buffering properties of the PCM improves thermal comfort. The flexible foams are useful in application such as matresses, pillows, automotive cushioning, shoe inserts, medical foams and the like. In my opinion especially useful for viscoleastic (“memory”) foams which are known to suffer from thermal discomfort problems.

Effect of "gel PCM" on heating rate of flexible foam according to the invention.

Effect of “gel PCM” on heating rate of flexible foam according to the invention.

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3 Comments

  1. Denis

     /  November 13, 2013

    Hi Geert
    Gels like this have been used in bedding since the late 90’s. There is a small sweet spot where they can have an effect and that is related to the heat capacity of the gel. Clearly once the gel has absorbed enough heat to phase change, its cooling capacity drops off. So the more gel, the longer the effect. But the more gel, the less foam for determining the comfort of the bed.

    And the polyol viscosity skyrockets at the gel content increases.

    The complaints about heat in visco beds is related to TDI based visco foam – they are hydrophobic, typically closed cell and soft. So the air transport in the bed is low and the moisture transport poor.

    Nothing to match the good high EO MDI visco foams;-)

    So someone needs to patent a super high specific heat capacity gel. It only needs to be at the surface of the bed where the temperature is affected by a persons body.

    Reply
    • Hello Denis,
      I believe you are confusing “gel” and “PCM” (phase change material). PCMs have indeed been used before in mattresses (and so have gels for that matter) but this case is about PCMs embedded in gels which are in turn embedded in an open celled foam. According to the inventors the gels improve the thermal conductivity of the foam which allows the “gel-PCM” to be applied with good effect throughout e.g. a mattress and not just on the surface. Maybe this can make you to stay cool until you fall asleep? :-)
      The temperature problem with visco foams is not only the thermal comfort, there is also the effect that the foams are hard when cold and soft when hot. The trick to solve this is to make a foam with a wide and ‘flat’ glass transition. I can tell you how to do that!

      Best regards
      Geert

      Reply
  2. Denis

     /  November 27, 2013

    Geert,
    Whether the pcm is in the foam or in a gel it still has a latent heat of fusion which determines how much heat it can absorb and that will be proportional to the mass added. So I can see it working for a short time but over hours I never personally felt an effect. The areas where I was impressed was in ski gloves where the pcm melted as you exerted energy going down and re- froze releasing energy sat on the chair lift going back up. The pcm was in a hypol-type foam.

    And for the hardness in the v-e, well yes your correct especially if the visco is too thick – it needs hardness to support the weight. But i always thought a thin, soft visco to smoth out the pressure points on a good HR is all you need to make a great mattress ;-).

    Reply

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