Abstract: The present invention pertains to improved alkenyl aromatic polymer foams (and processes for their preparation) having increased heat distortion temperature and improved dimensional stability while maintaining good tensile/tear, creep and environmental dimensional change properties.The closed cell low density alkenyl aromatic polymer foams exhibit increased heat distortion temperature, when substantially random interpolymers of about 21 to about 65 mol % styrene are blended in. When these same alkenyl aromatic polymer foams are made without these interpolymers, the heat distortion temperature is not improved.

Abstract: Disclosed herein is an molded article of foamed and expanded beads of a propylene resin, which is obtained by heating and molding the foamed beads of the propylene resin, wherein the apparent density of the molded article is 0.11 to 0.45 g/cm.sup.3, a value obtained by dividing its maximum bending strength (kgf/cm.sup.2) determined in accordance with JIS K 7221 by the apparent density (g/cm.sup.3) is at least 160 (kgf/cm.sup.2)/(g/cm.sup.3), and the average number of cells at its section is within a range of 5 to 100 cells/mm.sup.2.

Abstract: An absorbent, microporous foam comprising a crosslinked polymer having interconnected fluid cells distributed throughout its mass, wherein the fluid cells have a diameter of between about 0.1 and about 100 .mu.m, and wherein the foam can rapidly absorb at least about twice its dry weight in fluid, is disclosed.A method for producing a microporous, absorbent foam is also disclosed. This method comprises the steps of:(a) mixing a cross-linkable polymer and a first solvent to form a stable solution, wherein the stable solution can be induced to phase separate;(b) inducing the stable solution to phase separate into a polymer-concentrated phase and a polymer-dilute phase after a predetermined period of time;(c) inducing crosslinking of said polymer, so that the polymer will crosslink in said concentrated phase for a predetermined period of time during phase separation to thereby form a microporous material; and(d) drying the microporous material to produce the absorbent foam.

Abstract: A large-sized in-mold expansion-molded article of an olefin synthetic resin having 150 mm or more in thickness, 50% or more in fusion ratio and 10% or less in density distribution is disclosed. The expansion-molded article is obtainable by adoption of a process in which pre-expanded beads are charged into a mold, preheated and steamed before molding. Large-sized expansion-molded article of an olefin synthetic resin 500 mm or even more in thickness is obtainable by the present invention.

Abstract: The present invention provides polypropylene resin pre-expanded beads formed by shrinking polypropylene resin pre-expanded beads originally having a bulk density of not higher than 0.0930 g/cc to give them a bulk volume ratio of 10-75% at normal temperature and normal pressure, a manufacturing method thereof and an expansion-molding method with the aforementioned pre-expanded beads. According to this invention, it is possible to greatly reduce storing and transporting costs per unit weight of pre-expanded beads.

Abstract: Water sport equipment, such as surfboards, sailboards and the like formed of a molded foam composed of expanded polypropylene foam beads, having a density of approximately 3.75 PCF, melted together with steam pressure and improved methods for producing such equipment.

Abstract: Prefoamed particles of a polyolefin resin are produced by dispersing starting particles of the polyolefin resin, which contains a volatile foaming agent, in a dispersant in a pressure vessel, heating the resultant dispersion to a temperature of at least the softening point of the starting particles in said pressure vessel and then opening the vessel at one end thereof so as to release the starting particles and dispersant into an atmosphere of a pressure lower than the internal pressure of the vessel. The release of the starting particles and dispersant is performed while feeding a heating liquid.

Abstract: A method of producing a crosslinked, uniformly foamed article of a polypropylene resin is provided. The polypropylene resin containing a crosslinking agent and a foaming agent is extruded through a long-land die which is provided with a choking die at an intermediate portion thereof; a lubricant is provided on the inner surface of the long-land die; the crosslinking agent is decomposed in the front stage of the long-land die; and the foaming agent is decomposed in the rear stage of the long-land die.An ethylene-propylene random copolymer resin which contains 2 to 10 wt. % of ethylene and has a melt flow rate of 5 g/10 minutes or more at 230.degree. C. and a melt expansion ratio of 1.4 of less at 190.degree. C. is used as the polypropylene resin.

Abstract: This disclosure relates to a method for producing polyethylene open-cell foam materials, comprising a process step of pressurized heating at a temperature of 110.degree. to 135.degree. C. of a base compound consisting of polyethylene or a copolymer of polyethylene which has been compounded with an azodicarbonamide foaming agent and a bridging agent, in order to obtain a primary intermediate product with a cubical expansion coefficient of 1.0 to 2.0 times; a process step of heating the primary intermediate product under normal atmospheric pressure at a temperature of 150.degree..about.190.degree. C.

Abstract: An increased volume synthetic fiber consists of a porous central core and a large number of short porous lateral threads integral with the core and distributed along the whole length of the fiber so as to form a voluminous branching structure. The process used to produce the fiber consists of the mixing of a synthetic polymer with an expanding agent which expands when heated, then spinning by melting the mixture which results in the expansion and fringing of the threads produced, caused by the expansion agent, followed by the drawing and fixing of the threads thus produced while they are still hot.

Abstract: According to a method of manufacturing a foamed polypropylene resin sheet of this invention, a composition comprising as a resin component a mixture of 80 to 20 wt % of a crystalline propylene-ethylene block copolymer containing 20 wt % or less of ethylene and having a melt index (MI) of 2 or less and 20 to 80 wt % of a crystalline propylene-ethylene block or random copolymer containing 5 wt % or less of ethylene and having an MI of 6 to 20 or a polypropylene homopolymer having an MI of 6 to 20 is used. A pair of molding roll dies is horizontally arranged at a point separated from the center of an apex of an extrusion foaming die when a foamed sheet is to be extrusion-molded. A distance between the center of the roll and the apex of a base lip is set to fall within a range of (R.sup.2 +25).sup.1/2 to (R.sup.2 +144).sup.1/2 where R is a radius of the molding roll die.

Abstract: The present invention provides that, in a process for production of foamed articles of a polyproplene resin which comprises compressing pre-expanded beads of propylene resins under a gaseous pressure, filling a mold capable of closing but incapable of sealing with the compressed beads, then venting from the mold and heating and fusing with steam thereby to produce the molded article in the shape of the mold, the improvement wherein the pre-expanded beads of the polypropylene resins having two melting points when measured by differential scanning calorimetry and having a quantity of the peak fusion heat QH based on a melting point at a high temperature peak of the two melting points being 0.3 to 3.5 cal/g are introduced compressively into the mold so that a compressive rate is 10 to 60%.

Abstract: An expansion-molded article of a polypropylene resin is produced by filling pre-foamed particles of the polypropylene resin, which have a crystalline structure featuring an inherent peak inherent to the polypropylene resin and a high-temperature peak on the temperature side higher than the temperature corresponding to the inherent peak on a DSC curve obtained by differential scanning calorimetry of the pre-foamed particles and a bulk density of 0.04 g/cm.sup.3 or higher and require melting energy of 8-12 J/g at the high-temperature peak, in a mold without applying any pretreatment to the pre-foamed particles to build up an internal pressure therein, and then heating the pre-foamed particles, whereby the pre-foamed particles are caused to expand into the expansion-molded article conforming with the mold. The pre-foamed particles may alternatively have a bulk density lower than 0.04 g/cm.sup.3 and require melting energy of at least 8 J/g.

Abstract: A process is disclosed for the production of expanded particles of polymeric material wherein unexpanded particles of the material are contacted with a nitrogen-containing inorganic gas under a first pressure condition to impregnate the particles with the gas. The gas impregnated particles are heated to a temperature higher than the softening point of the material, and dispersed into a liquid medium. The resulting dispersion is subjected to a lower pressure to expand the particles. The expanded particles may be used as prefoamed particles for the molding of foamed articles.

Abstract: A method of producing a polypropylene resin molded product from foamed polypropylene particles is disclosed, which comprises introducing a pressurizing gas into foamed polypropylene particles having closed cells so that the particles have an internal gas pressure of from 0.3 to 2.5 Kg/cm.sup.2 G, charging the particles in a mold cavity while compressing the particles with a pressurizing inorganic gas until the initial apparent volume of the particles is reduced to 50 to 99%, removing the gas from the mold cavity while keeping the foamed particles in a compressed state, and introducing steam in the cavity to cause adhesion of the compressed foamed particles. The method produces a molded product having satisfactory appearance and excellent adhesion among particles in a shortened molding cycle.

Abstract: Prefoamed polypropylene-base particles have a crystalline structure featuring a high-temperature peak appeared on the higher temperature side than the peak inherent to polypropylene-base resins on a DSC curve obtained by differential scanning calorimetry upon heating 1-3 mg of the prefoamed polypropylene-base particles at a constant heating rate of 10.degree. C./min. to 220.degree. C. by means of a differential scanning calorimeter and the internal pressure decreasing velocity coefficient k of the particles is either equal to or smaller than 0.70 (k.ltoreq.0.70) at 25.degree. C. and 1 atm. The prefoamed polypropylene-base particles can be formed into an expansion-molded polypropylene-base article by imparting foamability to the particles, filling the resultant particles in a mold and then heating the particles so as to cause their expansion.

Abstract: A process for the production of expanded particles, which comprises providing an aqueous dispersion containing expandable particles which are formed of a polypropylene resin and which contain a blowing agent and an expansion aid and maintained at a temperature higher than the softening point of the resin and under a pressurized condition, and subjecting the dispersion to a lower pressure so that the expandable particles are expanded. The expansion aid is organic or inorganic solids having a particle size of 0.1 to 150 .mu.m and a melting point higher than the temperature at which the expansion of the expandable particles is performed and serves to improve the expansion ratio.

Abstract: A method for aging an expansion-molded body of polyolefin prepared by heating pre-expanded polyolefin particles within a mold involves cooling the molded body within the mold so that the molded body is not substantially smaller than the volume of the mold cavity and is temporarily expandable after being removed from the mold to not more than 110% relative to the volume in the mold cavity, removing the molded body from the mold, placing the molded body in an atmosphere substantially under atmospheric pressure and having a temperature of 25.degree. to 55.degree. C. lower than the melting point of the polyolefin while the volume of the molded body is 70 to 110% relative to the volume of the mold cavity and holding the molded body in this atmosphere until the temperature of the molded body is at least equal to the temperature of the atmosphere.

Abstract: Process and apparatus are disclosed for manufacturing foamed articles such as tubes used as pipe insulation, which tubes are of a high impermeability and flexibility and are formed of a polymer, such as polyethylene or polypropylene, containing up to about 25% of an elastomer.

Abstract: A process for producing a highly expanded polypropylene foam which is uniform in viscosity during extrusion foaming, improved in melt strength and free from unevenness of surface by using a polypropylene resin having a specified melt tension.

Abstract: A core material for automobile bumpers which is composed of a molded article of foamed particles of a polypropylene-type resin. The molded article has a density of 0.015 to 0.045 g/cm.sup.3 and a compression stress at 50% compression of at least 1 kg/cm.sup.2. The core material simultaneously has excellent energy absorbing property and dimensional recovery and a low density.

Abstract: A process for producing a foamed and molded article of a polypropylene resin, which comprises pressurizing preliminarily-foamed particles of an ethylene/propylene copolymer having a melt index value of from 0.1 to 25, a latent heat of crystallization of not more than 28 cal/g and an ethylene content of from 1 to 30% by weight as a base resin with an inorganic gas or a gaseous mixture of the inorganic gas and a volatile blowing agent thereby to impart an elevated pressure to the inside of said particles, thereafter filling said particles in a mold capable of enclosing the particles but allowing escape of gases therefrom, and then heating said particles to expand them to the configuration of the mold.

Abstract: In producing a crosslinked polypropylene foam, 0.5 to 4 parts by weight of a compound selected from triacrylate and trimethacrylate of aliphatic polyhydric alcohol and a blowing agent are mixed with 100 parts by weight of propylene homopolymer or copolymer. Then, the mixture is shaped under heat, followed by irradiation with an ionizing radiation such that the dose of the radiation absorbed by the shaped mass ranges between 0.1 and 10 Mrad. Finally, the irradiated mass is heated for foaming.

Abstract: Compositions comprising propylene polymer, e.g., polypropylene, and hydrated alumina as filler precursor and sole blowing agent, wherein the alumina can be 30 to 60 weight percent of the total composition, are converted into foam having a fine and uniform cellular structure by passage through an unvented extruder at specified temperature profiles and pressures.

Abstract: In a process for producing a foamed article of a polyolefin resin which comprises filling in a mold pre-foamed particles of a polyolefin resin containing a gaseous mixture consisting of an inorganic gas and a volatile organic blowing agent in their cells and heating them to mold a foamed article; the improvement wherein the pre-foamed particles of the resin are those in which the total pressure of the gaseous mixture is 1.4 to 2.5 kg/cm.sup.2 (abs.), with the partial pressure of the inorganic gas being maintained at 0.4 to 1.1 kg/cm.sup.2 (abs.) and the partial pressure of the volatile blowing agent at 0.8 to 1.6 kg/cm.sup.2 (abs.).

Abstract: In producing a crosslinked polypropylene foam, 0.5 to 4 parts by weight of a compound selected from triacrylate and trimethacrylate of aliphatic polyhydric alcohol and a blowing agent are mixed with 100 parts by weight of propylene homopolymer or copolymer. Then, the mixture is shaped under heat, followed by irradiation with an ionizing radiation such that the dose of the radiation absorbed by the shaped mass ranges between 0.1 and 10 Mrad. Finally, the irradiated mass is heated for foaming.

Abstract: A process is provided for preparing propellant compositions including a film-forming synthetic polymer that are capable of forming foamed structures containing open and/or closed cells, which may optionally contain a material which is deposited in the pores and/or walls of the structure as the structure is formed, which comprises coating the synthetic polymer in particulate form with an inert solid material insoluble in the propellant and in solutions of the synthetic resin the propellant at atmospheric temperature; and then adding the propellant and dissolving the synthetic polymer in the propellant.

Abstract: Foams of polypropylene resin composition having remarkably improved extrusion foaming characteristics are prepared by a non-crosslinking extrusion foaming process comprising mixing and kneading polypropylene resin and 1,2-polybutadiene resin so that 1,2-polybutadiene resin reacts under the influence of the heat and shearing stress in the extruder, and extruding thereafter.

Abstract: Unitary molded plastic hinged article and method of making in which a fluid molten mixture of heat softenable resin and a blowing agent in substantially unfoamed condition is introduced into an expandable mold cavity to fill the cavity and the mold is expanded to allow foaming of the resin to form at least one foam cored article section while the resin adjacent the mold surface is still fluid and in which the hinge structure is formed by a member adapted to form a thin, flex portion and portions transitional from the thickness of the flex portion to the thickness of a cored article section, the shaping member being slidably disposed in an aperture in the mold with portions of the walls of the aperture exposed within the mold cavity at the time the molten mixture is introduced and the exposed portions of the walls being wiped by the shaping member when the mold is expanded.

Abstract: An improved process is provided for producing cigarette filters comprised of a substantially open-cell foamed thermoplastic polypropylene resin wherein a mixture comprising a thermoplastic polypropylene resin, a volatile blowing agent and a nucleating agent is extruded through a die to produce a strand of foamed resin with the strand then being cut into individual filter elements. The improvement comprises employing as a primary nucleating agent from 0.1 to 40 percent by weight, based on the weight of the resin, of a particulate compound of a metal selected from Groups IIA, IIIA or IVA of the Mendeleef periodic table of elements together with from 0.01 to 5.0 percent by weight, based on the weight of the primary nucleating agent, of a synergist consisting of an organic compound having a hydrophobic group and a hydrophilic group. A particularly effective combination is the use of calcium carbonate as the primary nucleating agent and potassium benzoate as the synergist compound.