Abstract: A porous material made of a dry gel of a polyimide resin having an apparent density of 800 kg/m3 or less and a mean pore size of 1 &mgr;m or less is disclosed. The porous material exhibits high heat resistance and is low in density and mean pore size. The use of the porous material provided by the present invention can produce not only a heat insulator with a low thermal conductivity and high heat insulation but also an insulating material having a low dielectric constant and exhibiting excellent dielectric characteristics at high frequencies. The present invention can also provide a semiconductor circuit including the insulating material.

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: Pre-expansion of expandable polystyrene (EPS) and other expandable polymer beads has long been carried out with heat of condensation from steam, which permeates the beads and deposits water droplets within expanding cells of each bead. Because long conditioning periods (to dry the pre-expanded beads) allow much of the blowing agent (e.g. pentane) to escape, the resultant pre-expanded beads often lack sufficient pentane to permit adequate final expansion when the pre-expanded beads are used to mold coffee cups and other articles. When conditioning periods are too short, excess water droplets often cause variations in bead fusing and even leaks in the molded product. The present invention avoids these long-standing problems by using a heated gas, such as air, to pre-expand the raw EPS beads through conduction only.

Abstract: A breathing film comprising at least one layer obtained by processing a propylene resin composition including crystalline propylene polymer(A) and propylene/&agr;-olefin random copolymer(B) is provided, said film having anti-bacterial agent, and the ratio [&eegr;]B/[&eegr;]A of intrinsic viscosity [&eegr;]B of propylene/&agr;-olefin random copolymer(B) and intrinsic viscosity [&eegr;]A of crystalline propylene polymer(A) being 0.3 to 1.2, and said film having specified range of water vapor permeability, oxygen gas permeability and ethylene gas permeability.

Abstract: Stable foam caulk, sealant and insulation compositions are disclosed. The compositions comprise solid, waxy non-ionic lipophilic surfactants having low HLB values. These surfactants, upon foamed dispensing of the composition, provide stable support for bubbles formed from drying of a latex emulsion of a film forming polymer and a volatile liquid hydrocarbon propellant. In addition to use in caulking, sealant or insulation methods, the composition can be used to form artificial terrains and other hardenable structural surfaces as backgrounds or support means for hobbies, crafts, and the like.

Abstract: An object of this invention is to provide a method for the production of a porous material by polymerizing a water-in-oil type high internal phase emulsion in a briefer time than a conventional technique without impairing the stability of the emulsion. The object of this invention can be accomplished by a method for the production of a porous material comprising a step of polymerizing a water-in-oil type high internal phase emulsion containing a polymerization initiator, wherein the polymerization initiator is a redox type initiator combining a water-soluble oxidizing agent and a reducing agent, the reducing agent is preparatorily added to form the emulsion, and thereafter the water-soluble oxidizing agent is added to the emulsion to polymerize the added emulsion.

Abstract: The invention concerns nucleating agent systems for foamable polymer compositions, preferably fluoropolymer resins, having foam cell nucleation sites using titanium dioxide based nucleating agents, and foamable polymers comprising the nucleating agents. The nucleating agent systems comprise TiO2, certain inorganic salts, and, optionally, sulphonic acid and/or phosphonic salts. The invention also concerns foamable composition concentrates and foamed thermoplastic insulation material comprising fluoropolymer agent systems.

Abstract: This invention describes grafted blend compositions, processes for their preparation and fabricated articles, especially foams therefrom. The blends exhibit enhanced melt strength, melt elongation greater than or equal to about 20 mm/s, increased upper service temperature, increased modulus, and increased hardness. The grafted blend compositions have little or no high shear viscosity increase over a corresponding polymer of the same chemical composition absent the coupling agent.

Abstract: There is provided a porous material suitable for use in a bearing retainer, having such properties as a small contraction ratio of the dimensions of a formed workpiece to those of a finished product, excellent hot oil resistance, small contraction change, insusceptibility to damage, light weight, a long service life, and ability to retain oil and grease for a long period of time. The porous material suitable for use in the bearing retainer is obtained by a process comprising the steps of mixing degreased bran derived from rice bran with a thermosetting resin before kneading, subjecting a kneaded mixture to a primary firing in an inert gas at a temperature in a range of 700 to 1000° C.

Abstract: An object of this invention is to provide a method for the production of a porous cross-linked polymer, which permits the polymerization (curing) of a water in oil type high internal phase emulsion (HIPE) in such an exceptionally brief time as not more than 30 minutes, preferably not more than 10 minutes without impairing the stability of the HIPE. The object of this invention mentioned above can be accomplished by a method for the production of a porous cross-linked polymer which comprises steps of mixing an oil phase containing a polymerizing monomer, a cross-linking monomer, and a surfactant as essential components with a water phase containing water as an essential component thereby obtaining a water in oil type high internal phase emulsion and heating said emulsion to a prescribed curing temperature thereby polymerizing the emulsion, wherein said emulsion is formed in a thickness of not more than 50 mm and the temperature-increasing rate of the emulsion is not less than 5° C./minute.

Abstract: The invention disclosed provides a method for inducing nucleation in a polymer by subjecting the polymer containing dissolved gas to an external stress generated, for example, by applying hydrostatic or mechanical pressure. The applied stress restricts the bubble growth so that the foamed materials have small cells and high cell density. Such microcellular foams can be produced over a wide low temperature range, i.e. from the temperature at which the polymer is conditioned with the blowing agent up to about the glass transition temperature of the polymer-blowing agent system. Stress induced nucleation can also be conducted at higher temperatures i.e. up to about the Tg of the neat polymer, leading to foams with larger cells. A variety of homogeneous and heterogeneous foams can be produced by this technique.

Abstract: A silicone rubber sponge composition comprising an organopolysiloxane, finely divided silica, a blowing agent in the form of a non-cyano type organic azo compound, typically dimethyl 1,1′-azobis(1-cyclohexane carboxylate), and a curing agent is effectively blowable into a silicone rubber sponge which is safe without a need for long-term post-cure, contains uniform fine cells and has a smooth, tack-free skin layer.

Abstract: The invention relates to a process for preparing styrene polymers which comprise water as sole blowing agent, by polymerizing styrene in aqueous suspension in the presence of from 0.1 to 15% by weight of a solid substance insoluble in water and in styrene, for example carbon black or graphite.

Abstract: There is disclosed a porous moisture-absorbing and desorbing polymer, characterized in that, said polymer is an organic polymer containing 2.0-12.0 meq/g of carboxyl groups of a salt type, having a cross-linking structure and having macropores of not less than 1 m2/g of specific surface area and 0.005-1.0 &mgr;m of average pore size.

Abstract: Macroporous polymers having selected porosity and permeability characteristics that provide rigid polymer matrices suitable for use in medium and high pressure reversed phase liquid chromatography (RPC) are disclosed. A method for preparing the polymers using selected mixed porogens in selected proportions relative to the monomer phase is also disclosed. The polymers are especially useful as stationary phases in large scale chromatography columns without developing increased pressures during prolonged use, while maintaining good chromatographic performance for targeted biomolecules, such as insulin.

Abstract: The product made of crosslinked polyolefin foam of the invention is characterized by a compression of at most 7 N/cm2, measured according to the ASTM D 1667 standard with a degree of compression of 30% and a rate of compression of 10 mm/minute, for a density of at least 100 kg/m3, it being understood that this maximum compression may decrease for lower densities and increase for higher densities. The invention comprises, moreover, the application of this product as a seal.

Abstract: A closed-cell polymer foam having a density of less than 100 kg.m−3 is described. The cells in the foam contain a foam blowing agent comprising (a) a blend of two or more hydrofluorocarbons, (b) a blend comprising a carbon dioxide and one or more hydrofluorocarbons or (c) a blend comprising dimethyl ether and one or more hydrofluorocarbons, and the polymer is a blend comprising at least 50% by weight of an olefinic polymer(s) and up to 50% by weight of a polar polymer(s) having a lower molecular weight than the olefinic polymer which when in the heat plasticised state is able to dissolve the foam blowing agent. A process for preparing the foam is also described.

Abstract: The invention relates to a process for the preparation of expandable able styrene polymers containing particles of graphite by polymerization merization of styrene in aqueous suspension in the presence of particles of graphite having a mass density of less than 1.8 g/cm3.

Abstract: A method using a two part process line is proposed for manufacturing foams from polymers or polymer mixtures useful for making molded bodies. The process line is divided into at least one first part and one second part. The polymer or polymer mixture is melted in the first part and a gas at a pressure increased relative to the melt pressure is added with the influence of a shearing and/or kneading device on the melted polymer or polymer mixture enriched with gas. In the second part of the process line, foam is formed from the gas-enriched polymer or polymer mixture at a higher pressure than the pressure in the first part of the process line. Membranes can be made from the molded bodies made by the method described above.

Abstract: A method of enhancing the melt-processibility of crosslinked plastic or recycling crosslinked plastic and the products formed by these methods. The melt processibility of a crosslinked thermoplastic resin may be enhanced by mixing it with a low viscosity polymeric resin having a specified melt flow index relative to the melt flow index of the crosslinked thermoplastic resin, and exposing the mixture to mechanical shearing energy to produce a processed mixture having enhanced melt flow characteristics. The processed mixture may be subsequently mixed with thermoplastic polymer.