Abstract:
The present invention provides a process for producing a foamed resin article, the process comprising: a step (the first step) of impregnating any one crystalline thermoplastic resin or resin composition containing, as an elementary ingredient, a crystalline thermoplastic resin selected from a certain group, under an elevated pressure which is not lower than the critical pressure of a substance with which the selected crystalline thermoplastic resin or resin composition is to be impregnated, with a fluid of the substance, and a step (the second step) of releasing the resin or resin composition impregnated with the substance from the foregoing pressurized condition in a period of less than 10 seconds.
Abstract:
A heat-resistant polymer foam is disclosed which has excellent heat resistance, a fine cellular structure, and a low apparent density. The heat-resistant polymer foam comprises a heat-resistant polymer having a glass transition point of 120null C. or higher, e.g., a polyimide or polyether imide, and has an average cell diameter of from 0.01 nullm to less than 10 nullm. This heat-resistant polymer foam can be produced by, for example, impregnating a heat-resistant polymer under pressure with an non-reactive gas such as carbon dioxide, which is in, e.g., a supercritical state, reducing the pressure, and then heating the polymer at a temperature exceeding 120null C. to foam the polymer.
Abstract:
A flexible, low density thermoplastic foam and a method for lowering the density and increasing the flexibility of a thermoplastic foam having a melting temperature and being either amorphous with a softening temperature or semicrystalline with a glass transition temperature. The method comprises the steps of (a) decreasing the pressure on the thermoplastic foam to a subatmospheric pressure, farther providing that while the thermoplastic foam is under the subatmospheric pressure, the thermoplastic foam is also at a temperature in the range of less than the melting temperature and greater than the softening temperature if the thermoplastic foam is amorphous, or greater than the glass transition temperature if the thermoplastic foam is semicrystalline, whereby the thermoplastic foam expands; (b) then exposing the thermoplastic foam to a superatmospheric pressure and a secondary expansion gas for a sufficient amount of time to allow the secondary blowing gas to permeate into the thermoplastic foam; and (c) then releasing the superatmospheric pressure on the thermoplastic foam whereby the thermoplastic foam expands. With this method, it is possible to produce thermoplastic foams having densities as low as 0.008 grams/cc. Also included in his invention are insulations made from these low density foams.
Abstract:
The present invention relates to an expanded product comprising a thermoplastic fluroine type resin which does not have a cross-linking structure and has an expansion ratio of between 4-fold and 30-fold and a closed cell percentage of 40% or more. The expanded product contains at least one interface comprising layers having different cell densities and has a distribution index (Sc) and a coefficient of variation (Cv) of the maximum diameter of an open cell present at an optional cross section of each layer of 0
Abstract:
A structure of synthetic resin foam has a core layer of thermoplastic resin foam and skin layers of non-foamed thermoplastic resin merged with the core layer, and the skin layers gives rise to increase the mechanical strength of the structure.
Abstract:
The process of enabling foam moldings to expand further than otherwise by impregnating the expanded sheet with inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens prior to reheating to effect expansion.
Abstract:
The process of enabling foam moldings to expand further than otherwise by impregnating the expanded sheet with inorganic gases such as carbon dioxide, nitrogen, air and other pneumatogens prior to reheating to effect expansion.