Abstract: The mixture of water and the polyolefin resin particles impregnated with a volatile blowing agent are released from the interior of the pressure-resistant container under a constant temperature and constant pressure preferably keeping the partial pressure of the blowing agent constant, through at least one orifice having an area of 0.07 to 300 mm.sup.2, into a low-pressure zone.This invention gives various advantages when applied to the practical process resulting in expanded particles with superior properties which are free of blocking and remarkably uniform in the degree of expansion, and are useful for molding.

Abstract: A method for pressurizing pre-foamed particles of a polyolefin resin by maintaining the pre-foamed particles in an atmosphere of a pressurized gas to impart a predetermined internal pressure thereto, which comprises first maintaining the particles under a pressure which does not cause shrinkage to the particles, and then increasing the applied pressure gradually under conditions which do not cause shrinkage to the particles.

Abstract: The invention relates to a process of expanding styrene beads which comprises expanding said beads in the presence of a surfactant having a HLB value of 3 to 18 and showing a surface resistance less than 10.sup.14 .OMEGA./cm. By the process, blocking of beads is prevented, antistatic effect can be given to the shaped article and saving of steam used in the course of expanding is achieved.

Abstract: In a process for producing pre-foamed particles of a polyolefin resin which comprises impregnating a volatile blowing agent into particles of a polyolefin resin while dispersing the resin particles and the blowing agent in a dispersing medium under heat in a closed vessel, opening one end of the vessel and releasing the resin particles and the dispersing medium simultaneously into an atmosphere kept at a lower pressure than the inside pressure of the vessel; the improvement wherein the pressure of the inside of the vessel after opening its one end is maintained at a substantially constant pressure which is at least 0.7 times the vapor pressure of the blowing agent before opening the end of the vessel.

Abstract: Disclosed is the preparation of micro-bits of expanded styrene-polymers and of expanded polyolefins by comminuting the styrene-polymer or polyolefin in a particular combination of comminuting steps in a suitable comminutor that can provide that combination of steps and in the presence of water as a cooling agent. The polymer micro-bits, which are produced as an aqueous slurry, may be rendered dry-to-the-touch by vacuum filtration followed by passage through a filter press.

Abstract: An expanded shaped article of a heat resistant synthetic resin comprising 20 to 100 weight percent tertiary butyl styrene and 80 to 0 weight percent other monomers polymerizable therewith, and containing volatile foaming agent, wherein expandable particles of said resin are pre-expanded by application of heat and then molded by application of heat to produce shaped articles. Extrusion foaming may be used to form the article.

Abstract: Fine particulate expandable flame retardant styrene polymers having an improved minimum mold dwell time and reduced block shrinkage are prepared by:(a) mixing together styrene monomer or a mixture of styrene and a cpolymerizable monomer with an organic halogen compound and an expanding agent in an aqueous disperson;(b) adding before or during polymerization to the mixture of (a) from 0.0001 to 0.1% by weight of an epoxidation product of an aliphatic hydrocarbon of which the epoxidated aliphatic chain comprises from 6 to 18 C atoms, this epoxidation product being soluble in the monomers;(c) carrying out a polymerization in the aqueous suspension of (a) and (b) using radical forming initiators at temperatures of 80.degree. C.-130.degree. C. to form expandable particles;(d) pre-forming the expandable particles resulting from (c);(e) ageing the pre-formed particles of (d); and(f) molding the pre-formed and aged particles of (e) in a pressure resistant mold.

Abstract: Fire retardant, expanded styrene polymer shaped objects are prepared by:(a) mixing styrene monomer or a mixture thereof with at least one comonomer, an expanding agent and a fire retardant, organic halogen compound in a aqueous dispersion;(b) adding to (a) either before or during polymerization from about 0.0001 to 0.1 percent by weight esters soluble in the organic phase of (a), these esters of aliphatic dicarboxylic acids and aliphatic epoxy alcohols having at least 11 carbon atoms;(c) polymerizing the aqueous dispersion of (a) and (b) using radical forming initiators at a temperature of about 80.degree. to 130.degree. C.;(d) separating bead polymers having diameters between about 0.4 and 3 mm;(e) pre-foaming the beads;(f) ageing the pre-foamed beads; and(g) final forming the aged and pre-foamed beads in a pressure resistant mold.

Abstract: A substantially water-impermeable polyolefin foam made of expandable polyolefin beads. The polyolefin foam is prepared by a particular process in which after heating expandable polyolefin beads and before cooling the heated beads in a mold, the heated beads were allowed to stand in the state that the polyolefin resin maintains the flowability.

Abstract: Fine particulate expandable flame retardant styrene polymers having an improved minimum mold dwell time and reduced block shrinkage are prepared by:(a) mixing together styrene monomer or a mixture of styrene and a copolymerizable monomer with an organic halogen compound and an expanding agent in an aqueous dispersion;(b) adding before or during polymerization to the mixture of (a) from 0.0001 to 0.1% by weight of an expoxidation product of an aliphatic hydrocarbon of which the epoxidated aliphatic chain comprises from 6 to 18 C atoms, this epoxidation product being soluble in the monomers;(c) carrying out a polymerization in the aqueous suspension of (a) and (b) using radical forming initiators at temperatures of 80.degree. C.-130.degree. C. to form expandable particles;(d) pre-forming the expandable particles resulting from (c);ageing the pre-formed particles of (d); and(f) molding the pre-formed and aged particles of (e) in a pressure resistant mold.

Abstract: Fire retardant, expanded styrene polymer shaped objects are perpared by:(a) mixing styrene monomer or a mixture thereof with at least one comonomer, an expanding agent and a fire retardant, organic halogen compound in a aqueous dispersion;(b) adding to (a) either before or during polymerization from about 0.0001 to 0.1 percent by weight esters soluble in the organic phase of (a), these esters of aliphatic dicarboxylic acids and aliphatic epoxy alcohols having at least 11 carbon atoms;(c) polymerizing the aqueous dispersion of (a) and (b) using radical forming initiators at a temperature of about 80.degree. to 130.degree. C.;(d) separating bead polymers having diameters between about 0.4 and 3 mm;(e) pre-foaming the beads;(f) ageing the pre-foamed beads; and(g) final forming the aged and pre-foamed beads in a pressure resistant mold.

Abstract: The steam expander conveys the expanding heat expandable thermoplastic elements along a horizontal axis using a plurality of paddle frames. The paddle frames serve to agitate and tumble the elements during movement from an inlet to an outlet. At the same time, steam is injected into the housing of the expander to expand the elements. The expanded elements can be drawn off via a vacuum line to an overhead hopper or hoppers.

Abstract: An expansion-molded product made from expanded cross-linked polyethylene particles each of which has an outer skin and inner cellular core, said outer skin each being fused and welded together to form an interfacial membrane whose average thickness is as thick as at least three times that of a cell membrane of the inner cellular core, is prepared by charging a lot of the particles into a mold, heating the particles therein to such an extent that the space among the particles is filled and then aging thus obtained molded product.The expanded particle each has a structure having an outer skin on an inner cellular core, the outer skin being as thick as at least three times cell membrane of the inner cellular core. The expandable particles are prepared by impregnating a foaming agent into the cross-linked polyethylene particles and heating so that the expandable particles are subjected to a step in which the foaming agent existing in the surface thereof is preferentially forced to evaporate.

Abstract: A process for the expansion of an expandable, polymeric, bead material by exposing the bead material to steam at an elevated temperature, to effect the expansion of the bead material into a polymeric bead material form, while tumbling the bead material during expansion to prevent fusion, the improvement which comprises: employing as a lubricant for the bead material a lubricant material which, on exposure to the steam and prior to the end of the expansion of the bead material, is changed in lubricant characteristics, to provide an expanded, polymeric foam bead material having a reduced surface lubricity.

Abstract: Expandable thermoplastic polymer beads are introduced into a tank and are agitated therein in a heated moisture-free condition. The beads are pressurized within the tank with a hot gaseous medium to soften them and are then subjected within the tank to a selected degree of vacuum to expand the beads or particles. The vacuum is removed and atmospheric pressure is re-established in the tank. The expanded hot moisture-free particles are introduced into a mold where they are fused into an integral mass, followed by cooling of the fused mass within the mold to form an outer skin on the mass. The fused mass is ejected from the mold.

Abstract: Expandable thermoplastic polymer beads are introduced into a tank and are agitated therein in a heated moisture-free condition. The beads are pressurized within the tank with a hot gaseous medium to soften them and are then subjected within the tank to a selected degree of vacuum to expand the beads or particles. The vacuum is removed and atmospheric pressure is re-established in the tank. The expanded hot moisture-free particles are introduced into a mold where they are fused into an integral mass, followed by cooling of the fused mass within the mold to form an outer skin on the mass. The fused mass is ejected from the mold.

Abstract: Expandable thermoplastic polymer beads are introduced into a tank and are agitated therein in a heated moisture-free condition. The beads are pressurized within the tank with a hot gaseous medium to soften them and are then subjected within the tank to a selected degree of vacuum to expand the beads or particles. The vacuum is removed and atmospheric pressure is re-established in the tank. The expanded hot moisture-free particles are introduced into a mold where they are fused into an integral mass, followed by cooling of the fused mass within the mold to form an outer skin on the mass. The fused mass is ejected from the mold.

Abstract: Expanded particles of a crosslinked polyolefin resin, each particle with uniformly spherical shape, having an average diameter of 1.4 to 5.5 mm, an average expansion ratio of 18 to 37 and specific compression coefficient of 1.6 .times. 10.sup.-3 to 4.0 .times. 10.sup.-3, are found to be produced by two-step foaming operations. They are useful for various purposes such as filtrating material, fillers in stuffed specimens and, especially for preparation of molded articles having constricted portions, giving excellent moldings having smooth surface without failure at corner or edge portions.

Abstract: A method and apparatus for forming foam articles is described. Thermoplastic resin beads containing a blowing agent are continually agitated in a heated pre-expansion chamber to a temperature near the fusion point of the beads and above the boiling point of the blowing agent at substantially atmospheric pressure. The beads soften and expand substantially in volume. A dry gaseous medium may be swept over the beads to remove moisture and any blowing agent which has escaped. Thereafter, the chamber is evacuated. Evacuation continues until a predetermined amount of blowing agent is removed from the beads. As a preferred embodiment of the invention, steam may be injected into the chamber prior to evacuation. This serves to further expand the beads, and facilitates the removal of the blowing agent. This embodiment also provides a means of manufacturing particularly stable low-density foam.

Abstract: Expanded particles of a crosslinked polyolefin resin, each particle with uniformly spherical shape, having an average diameter of 1.4 to 5.5 mm, an average expansion ratio of 18 to 37 and specific compression coefficient of 1.6.times.10.sup.-3 to 4.0.times.10.sup.-3, are found to be produced by two-step foaming operations. They are useful for various purposes such as filtrating material, fillers in stuffed specimens and, especially for preparation of molded articles having constricted portions, giving excellent moldings having smooth surface without failure at corner or edge portions.

Abstract: The present invention provides an apparatus for the manufacture of pre-expanded particles, which comprises in combination a heat-insulated resonating cavity, with a high-frequency electromagnetic source of energy, a ferrite circulater, a wave guide, an Archimedes screw for the introduction of the plastics material to be pre-expanded, a pump for regulating the feed of polar liquid and a device for extracting the pre-expanded particles. The present invention provides also a process for the pre-expansion of particles of plastic material using said apparatus.

Abstract: Continuous method and apparatus for treatment of a solid material submerged in a body of liquid wherein the material is sticky and/or has weak tensile strength. The material is supported, while it is so submerged, by a dynamic layer of the liquid lying between the material and a moving surface. The method is illustrated by heating and thereby foaming a strip of heat foamable thermoplastic resin while it is held submerged in a denser heat transfer liquid by a dynamic layer of that liquid generated by a moving belt above the foaming material. In an example, expandable high density polyethylene strip is foamed continuously while it is so held submerged in molten salt.

Abstract: Thermoplastic material in particulate form and containing a blowing agent is partially expanded by means of a mixture of steam and another hot dry gas such as air present in specified proportions in said mixture.

Abstract: An energy saving and material conserving apparatus is provided for expanding and molding expandable thermoplastic polymer particles. Especially significant is the ability to produce molded objects of generally uniform density in the higher density range in the order of 4 - 15 pounds per square inch, or greater, as well as lower density molded objects due to improved control of the particle expansion.The particles are partially expanded in a vessel in a heated substantially dry atmosphere and agitated in a manner to provide uniform heating thereof. After an initial heating period to soften and partially expand the particles they are subjected to superatmospheric pressure to substantially prevent further expansion and are discharged and conveyed to a mold for further expansion therein.

Abstract: An energy saving and material conserving method and apparatus are provided for expanding and molding expandable thermoplastic polymer particles. Especially significant is the ability to produce molded objects of generally uniform density in the higher density range in the order of 4-15 pounds per square inch, or greater, as well as lower density molded objects due to improved control of the particle expansion.The particles are partially expanded in a vessel in a heated substantially dry atmosphere and agitated in a manner to provide uniform heating thereof. After an initial heating period to soften and partially expand the particles they are subjected to superatmospheric pressure to substantially prevent further expansion and are discharged and conveyed to a mold for further expansion therein.

Abstract: A complex is formed by the reaction of an aluminum salt such as aluminum sulfate with a high molecular weight (for example, above 60,000 M.W.) collagen. Collagen-aluminum complex is dispersed in water and serves as suspension agent for suspending polystyrene beads during impregnation of a blowing agent, even when the concentration of the suspending agent is of the magnitude of 0.05% by weight of the beads. The aqueous system is drained from impregnated expandable beads, which are washed, but which retain adherent deposits of said collagen-aluminum complex in measurable amounts. The dried coated beads have minimized propensity toward lumping when pre-expanded. The prepuffed particles can pass tests concerned with resistance toward static electrical phenonomen better than corresponding prepuffed particles lacking such deposit of collagen-aluminum complex.

Abstract: Expandible particles of styrene polymers are prepared by a process in which the polymerization of styrene, or of mixtures of styrene and monomers copolymerizable with it, and/or treatment of the expandible particles prior to expansion thereof, are (is) carried out in the presence of dimers or trimers of unsaturated fatty acids or their esters with C.sub.1 -C.sub.18 alcohols.

Abstract: A method and apparatus are disclosed for the manufacture of foamed polystyrene particles of moderately great density, such as 3 to 25 lbs. per cubic foot (50 to 400 milligrams per cubic centimeter). Beads are fed by a constant-displacement auger to an expander vessel having the form of, in its lowest part, a cylinder with a vertical axis, and thereabove, of a frustrum of an inverted cone having a base angle of about 83.degree. to 70.degree.. Steam is supplied to the vessel in an appropriate, controlled manner. The vessel also contains stator bars, to break lumps and retard the rotation of the material in the vessel, and rotating bars, to provide the necessary agitation. Desirably, the equipment includes a discharge chute of adjustable location, to facilitate adjustment of the residence time and consequently of the density of the expanded beads being produced.

Abstract: Molded articles are made from expandable thermoplastic resin material by pre-expanding the thermoplastic material in particulate or bead form containing as the principal expanding agent a liquid hydrocarbon by contact with steam until the desired degree of expansion is obtained, heating the beads in a stream of substantially dry, hot gas at a temperature above the boiling point of the hydrocarbon but below the fusion temperatures of the thermoplastic material while agitating the beads to prevent agglomeration upon softening until substantially all of the moisture is removed from the surfaces of the pre-expanded beads, and molding the article from the heated pre-expanded beads by placing them in a closed mold and heating them to a temperature above their fusion temperature, the temperature of the thermoplastic material being continuously maintained above the boiling point of the expanding agent from the time the beads are pre-expanded until they are molded into the shaped article.