The method of the present invention for producing a urethane-based
thermoplastic elastomer composition foam comprises the steps of:
adding and mixing 0.1 to 30 parts by weight of carbon dioxide (B) to 100
parts by weight of a urethane-based thermoplastic elastomer composition
(A) in a molten state, wherein said urethane-based thermoplastic elastomer
composition (A) comprises a urethane-based thermoplastic elastomer (A-1)
and other thermoplastic elastomer (A-2) in an (A-1)/(A-2) ratio of 20/80
to 99/1 by weight, to form a molten urethane-based thermoplastic elastomer
composition (C) which is in a state of a mixture of the urethane-based
thermoplastic elastomer composition (A) and the carbon dioxide (B) (gas
dissolving step); and
lowering a temperature of said molten urethane-based thermoplastic
elastomer composition (C) (cooling step).
The present invention can produce the urethane-based thermoplastic
elastomer foam of stable quality over a range from low foamed product to
highly foamed product by adding a given quantity of carbon dioxide in the
molten urethane-based thermoplastic elastomer quantitatively and stably.
It can also produce the foam excellent in flexibility, thermal insulation
and surface appearances. It is also excellent in safety, because of use of
carbon dioxide in place of the common foaming agent of
fluorochlorohydrocarbon or butane, thus causing no air pollution or
destruction of the ozone layer.
