Abstract: In a method of extruding a plastic product having a foamed core layer and at least one unfoamed skin layer by forcing contiguous flows of a resin through a coextrusion die, one of the flows containing a blowing agent and a nucleating agent for forming the core layer and the second of the flows containing only the blowing agent, for forming the skin layer, the steps of establishing a fluent stream of resin containing the blowing agent, dividing the stream into separate streams which are separately conducted to the coextrusion die to constitute the core-forming and skin-forming flows, respectively, and selectively adding the nucleating agent only to that one of the separate streams which constitutes the core-forming flow. The nucleating agent used can be one which is effectively completely expended when the core layer foams, so that the foamed product is essentially free of active nucleating agent.

Abstract: A foamed and expanded low density polyethylene sheet or tube possesses both superior buoyancy and thermal resistance characteristics. The sheet or tube is made by a process comprising mixing a low density polyethylene with a blowing agent, surface activation agent and, preferably, a separation agent, heating the mixture at different temperatures to first melt the mixture and then gasify the blowing agent to expand the polyethylene cells, cooling the melted mass to partially harden and shrink the expanded cells, further expanding the cells by introducing a second gaseous blowing agent, cutting, extruding and cooling the expanded mass, forming a sheet or tube from the cooling mass, and finally cooling the sheet or tube for at least 24 hours. A buoyant, thermal resistant, water-repellent and moisture resistant sheet or tube results, which can be used, for example, as a liner for garments, including sports, business and military garments and other related equipment.

Abstract: A method and apparatus for the production of a foamed thermoplastic material. A cavity transfer mixer is provided between a screw extruder which melts, or fuses, the thermoplastic material, and a cooler. The cavity transfer mixer enables the formation of uniform and well mixed admixtures of a foaming agent and a thermoplastic material and, optionally, other desired additives.

Abstract: A propellant is mixed with unsaturated polyester inside a first space (A) at a first pressure, for example at the atmospheric pressure. The polyester is then sprayed on the whole or parts of an open or exposed mould which is applied in a low-pressure chamber having a powerful negative pressure of 60-95% vacuum. In order to spray a first layer, polyester having a first amount of propellant is sprayed on the mould. At the initiation the propellant causes a powerful foaming effect at which bubbles are created and/or expanded in the polyester. In order to spray a second layer, which can be applied before or after the first layer, polyester having a second amount of propellant, or is without propellant, is sprayed on the mould, which causes fewer bubbles or no bubbles at all. The resulting polyester which comprises formed and expanded bubbles is bound (is allowed to tack rigid shape/is polymerized) by the use of a short tack-free time in the low pressure, said short time being preferably 5-10 minutes.

Abstract: A non-crosslinked foam of a composition comprising:(A) 72 to 98% by weight of a 1-butene polymer; and(B) 28 to 2% by weight of a propylene polymer, the percentages being based on the total weight of the 1-butene polymer and the propylene polymer.

Abstract: An expandable alkenyl aromatic polymer composition and methods of preparation are provided. The composition is admixed with a volatile blowing agent and an expansion aid which includes a polyphenylene ether. The composition may be extruded and then expanded by exposure to steam or hot air or may be impregnated with blowing agent and then expanded.

Abstract: A process for making molded high resilience polyurethane cellular products which require reduced crushing in preventing the products from substantially shrinking or changing dimensionally upon cooling which comprises: exposing the curing product to atmospheric pressure while in contact with the confines of the mold at a time when the cell walls of the curing polyurethane cellular product have cured sufficiently to develop sufficient strength to partially resist bursting by the pressure of said expansion gases contained within the cell walls upon exposure to atmospheric pressure, but before the cell walls have cured sufficiently to develop sufficient strength so that exposure to atmospheric pressure does not result in a reduction of the crushing force necessary to prevent the products from substantially shrinking or changing dimensionally.

Abstract: In a method of manufacturing silica-free, interconnected porous ceramics, use is made of ceramic material powder which exhibits an expansion phenomenon due to reaction when fired; the ceramic material powder is mixed with binder; the mixture is molded; thereafter the molded mixture is fired and, during the firing process, held for a predetermined period of time at a predetermined temperature which is not lower than a temperature at which maximum expansion occurs in the expansion phenomenon but lower than a temperature at which the firing of the molded mixture is completed; and the firing process is stopped after a lapse of the predetermined period of time.

Abstract: An expandable alkenyl aromatic polymer composition and methods of preparation are provided. The composition is admixed with a volatile blowing agent and an expansion aid which includes a polyphenylene ether. The composition may be extruded and then expanded by exposure to steam or hot air or may be impregnated with blowing agent and then expanded.

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: Moldable foam beads comprising a silane-crosslinked polyolefin foam are produced by mixing a composition comprising a silane-modified polyolefin (such as a silane-grafted polyethylene) and a silanol condensation catalyst in an extruder to produce a melt, then injecting a blowing agent into the melt at a rate effective to produce a desired foam density in the extrudate; extruding and cutting the melt to form foam beads; and exposing the foam beads to moisture to produce silane crosslinking of the polyolefin foam.

Abstract: A method for encapsulating electronic components in high acceleration and high thermal cycling environments. A liquid uncured thermal setting polyurethane formulation is mixed with a finely ground particulate foam which serves as a nucleating agent. The mixture is in accordance with the polyurethane formulation. The resultant foam contains open air pockets which allow it to be compressed and then re-expand.

Abstract: An expandable polyolefin composition and a method of preparation are provided. Isobutane or mixtures of isobutane with other physical blowing agents are utilized to expand polyolefin compositions which have been modified by the addition of a stability control agent. The composition has a high degree of dimensional stability and exhibits minimal shrinkage during curing and/or aging.

Abstract: Foamable and foamed polyvinlyidene fluoride materials prepared by compounding the PVDF with a suitable nucleating agent of discreet insoluble particles, a blowing agent having an activation temperature above the melting point of the PVDF, and a dispersing aid to provide a substantially homogeneous powdered mixture that is then melt compounded with high shear melt blending means and then extruded and quenched to provide the foamable polyvinylidene fluoride material which can then be extruded as an insulating material on wire at a temperature sufficiently high to activate the blowing agent.

Abstract: A steam expandable alkenyl aromatic polymer composition and methods of preparation are provided. The composition is mixed with a volatile blowing agent containing, as a primary blowing agent, dichlorodifluoromethane and as a secondary blowing agent, a halogenated hydrocarbon, a hydrocarbon, or an aliphatic alcohol containing from 1 to 4 carbon atoms, the secondary blowing agent having a normal atmospherpic boiling point of from about 0.degree. to about 100.degree. C. The composition may be expanded by steam immediately after extrusion foaming or may be expanded after aging of the composition which has been impregnated with volatile blowing agent.

Abstract: The present invention is a process for the preparation of polybenzimidazole foams. Polybenzimidazoles containing 10 to 30 percent by weight residual solvent can be heated at a temperature of about 350.degree. C. to about 600.degree. C. to produce three dimensional foamed articles.

Abstract: A method for making a ball having a cover and a core, which core has a spherical center and a winding, is disclosed. The ball is made by foam injection molding a thermoplastic resin comprising a mixture of at least about 45% of a copolymer of at least one olefin with at least one unsaturated monocarboxylic acid to form a spherical partially blown center. The center is then wound to form a wound core which is immersed in an adhesive which impregnates the yarn. The wound core is then dried and ironed the melt the surface of the center so as to fuse the windings to the center. A cover is then applied to the core to form the completed ball.

Abstract: A foamed polymethacrylimide resin having improved creep resistance at high temperature and reduced moisture absorption is obtained by heating a foamable resin composition consisting of (1) a copolymer formed between 47 to 53 percent by weight of methacrylonitrile monomer, 53 to 47 percent by weight of methacrylic acid monomer, and 0.01 to 4 percent, by weight of said monomers, of a metal salt of acrylic or methacrylic acid, and (2) 0.5 to 4 percent, also by weight of the monomers, of a blowing agent mixture of formamide or monomethyl formamide and a monohydric aliphatic alcohol having from 3 to 8 carbon atoms in the molecule.

Abstract: A steam expandable alkenyl aromatic polymer composition and methods of preparation are provided. The composition is mixed with a volatile blowing agent containing, as a primary blowing agent, dichlorodifluoromethane and as a secondary blowing agent, a halogenated hydrocarbon, a hydrocarbon, or an aliphatic alcohol containing from 1 to 4 carbon atoms, the secondary blowing agent having a normal atmospherpic boiling point of from about 0.degree. to about 100.degree. C. The composition may be expanded by steam immediately after extrusion foaming or may be expanded after aging of the composition which has been impregnated with volatile blowing agent.

Abstract: An expandable polyolefin composition and a method of preparation are provided. Isobutane or mixtures of isobutane with other physical blowing agents are utilized to expand polyolefin compositions which have been modified by the addition of a stability control agent. The composition has a high degree of dimensional stability and exhibits minimal shrinkage during curing and/or aging.

Abstract: An expandable alkenyl aromatic polymer composition and methods of preparation are provided. The composition is admixed with a volatile blowing agent and an expansion aid which includes a polyphenylene ether. The composition may be extruded and then expanded by exposure to steam or hot air or may be impregnated with blowing agent and then expanded.

Abstract: Water instead of carbon dioxide is substituted for part of the volatile organic blowing agent, e.g., pentane, resulting in extruded foams having a smooth, lustrous drum side skin compared to foams containing only organic blowing agent or organic blowing agent plus carbon dioxide.

Abstract: Ethylenic polymer/styrenic polymer blend foams are prepared from blends of (1) an ethylenic polymer resin having a density of from 0.915 to 0.930 g/cm.sup.3 and a melt index of from 0.2 to 2.6 grams/10 minutes and (2) a styrenic polymer resin having a melt flow rate of from 1.4 to 18 grams/10 minutes. Foams having an excellent overall combination of properties are obtained (1) when the density, D, of such foams is in the range of from 10 to 40 kg/m.sup.3 and the 25 percent compressive strength, F, in kg/cm.sup.2 is from 0.013D.sup.1.15 to 0.024D.sup.1.15 and (2) when the ratio, R, of the melt flow rate of the styrenic polymer employed divided by the melt index of the ethylenic polymer employed is from 7 to 90 and the content, Y, of the styrenic polymer in said blend, in parts by weight based upon 100 parts by weight of the ethylenic polymer resin, satisfies the following requirement:10.ltoreq.Y.ltoreq.3.94.7+1.18R-294.1 log (D).

Abstract: In a process for producing a polyethylene extruded foam, which comprises melting and kneading a composition of a polyethylene-based resin containing a foaming agent and extrusion-foaming it, a linear low-density polyethylene having a broadness of molecular weight distribution is used as the polyethylene-based resin. The linear low-density polyethylene used has a density of 0.920 to 0.940 g/cm.sup.3, a melt flow rate of 0.3 to 10 g/10 min's and a relationship Mw/Mw.gtoreq.4 between a weight average molecular weight and a number average molecular weight.

Abstract: The present invention relates to a process for the production of polyurethane-urea or polyurea-based microcellular of foam moldings by reacting a polyisocyanate component containing aromatically bound isocyanate groups with an isocyanate-reactive component containing at least one compound which has at least three aliphatic ether groups and aliphatically bound isocyanate-reactive groups and wherein a portion of the aliphatically bound-reactive groups are amino groups which have been converted to ammonium carbamate, carbonate or bicarbonate groups.The present invention also relates to the compounds containing aliphatic ether groups and ammonium carbamate, carbonate or bicarbonate groups, optionally in admixture with compounds containing unmodified amino groups or other known isocyanate-reactive compounds.

Abstract: An expandable polyolefin composition and a method of preparation are provided. Isobutane or mixtures of isobutane with other physical blowing agents are utilized to expand polyolefin compositions which have been modified by the addition of a stability control agent. The composition has a high degree of dimensional stability and exhibits minimal shrinkage during curing and/or aging.

Abstract: Styrene polymer foam is prepared using a mixed blowing agent of carbon dioxide plus ethyl chloride and optionally a fluorocarbon to provide a foam having primary cells and secondary cells formed in the struts and walls.

Abstract: The present invention relates to an improved nitro urea compound specifically the zinc salt of nitro urea useful as a blowing agent composition, its preparation and its use.

Abstract: In the case of a process for producing pourable spherical-segment-shaped packing material particles (18) made of plastic which have an external convex and an internal concave surface, the plastic material is mixed with additives, such as bubble forming agents, coloring pigments and similar agents. The plastic material is fed, by means of a feeding funnel (17) into an extruder (14) through an opening in a bush (13) surrounding the extrusion screw. The plastic material plasticizes over the course of the extruder (14) and, because of the difference in speed existing over the cross section of the mass, comes out of an opening (15) in the die with a bent surface. The plastic material is cut off directly at the opening (15) of the die and before any considerable expansion has taken place. Before the processing of the plastic granules in the extruder (14) a bubble-forming agent (nucleation agent) is applied to their surface in a drum (5).

Abstract: Expandable phenolic resin-coated composite beads comprise an aggregate having coated thereon a solid, expandable resin composition comprising a solid, phenolic resin initial condensation product, a foaming agent and, if necessary, a hardening agent. The expandable phenolic resin-coated composite beads provide composite cellular moldings in which the aggregates are uniformly dispersed in a phenolic resin-expanded layer and are firmly adhered to the expanded layer. The composite cellular moldings can be adhered to a face plate to form integral laminates.

Abstract: Methods of making low density modified polyimide/polyimide-amide foams and the resulting compositions. An N-substituted aliphatic imide is prepared by reacting a suitable aromatic dianhydride with a suitable oxime. A polyimide forming material is prepared by dissolving the N-substituted aliphatic imide in an esterifying solvent, then adding a suitable aromatic diamine. This material is dried to a powder. A suitable hydrated compound which is stable up to at least about 100.degree. C. is mixed with the powder. A foam is then produced by heating the material to reaction temperature for a period sufficient to produce a stable foam. The material melts, then spontaneously expands into a foam which becomes self supporting and cures to a resilient flexible foam. The addition of the hydrated compound is found to result in an exceptionally low density foam.

Abstract: A process for controlling bead size in the production of expandable styrene polymers by suspension polymerization is carried out by adding protective colloids to the aqueous phase before polymerization begins, such protective colloids being used which are homogeneously soluble in water over the entire temperature range from 25.degree. to 125.degree. C. and in which the concentration range being employed shall not lower the boundary surface tension water/styrene below 18 N/mm.sup.2. Lastly, the protective colloids are selected according to their molecular weight and the weight ratio of aqueous to organic phase lies in the range of 0.9:1 to 1:1.25, preferably in the range of 1:1. A grain spectrum is maintained predominantly greater than 0.41 to less than 2.5 mm by varying the molecular weights of the protective colloids.

Abstract: Foamable and foamed polyvinlyidene fluoride materials prepared by compounding the PVDF with a suitable nucleating agent of discreet insoluble particles, a blowing agent having an activation temperature above the melting point of the PVDF, and a dispersing aid to provide a substantially homogeneous powdered mixture that is then melt compounded with high shear melt blending means and then extruded and quenched to provide the foamable polyvinlyidene fluoride material which can then be extruded as an insulating material on wire at a temperature sufficiently high to activate the blowing agent.

Abstract: This invention discloses a vinylidene chloride resin type in-mold foam molding having a broad cross-sectional area and a free shape, useful as thermal insulating plate materials or anti-shock molded vessels, and foam particles or expandable particles convenient for preparation thereof, and also a series of advantageous foaming techniques for completion of such a molding. The above foam molding can be prepared by bringing fine particles of a non-crystalline vinylidene chloride type resin obtained generally by suspension polymerization into contact with a volatile organic blowing agent thereby impregnating the resins with the blowing agent to form expandable resin particles, which are in turn subjected to expansion as such, or after forming into pre-expanded foam particles including expandable gas therein, by filling in a mold cavity which can be closed but not sealed, under heating to form a molding through fusion mutually between the expanded particles.

Abstract: A polyphenylene oxide/polystyrene polymer blend foam structure having a density of less than about 20 lbs/ft.sup.3. The method of forming said foam comprising combining the polymer blend with a blowing agent member selected from the group consisting of methylene chloride, chloroform, 1,1,2-trichloroethane and mixtures thereof in molten form under pressure and extruding the same into a lower pressure region to form the foam.

Abstract: The present invention is a process for the preparation of novel polybenzimidazole foams. The foams exhibit a closed cellular structure and are prepared by forming a polybenzimidazole solution, adding sulfuric acid to the polybenzimidazole solution, removing the solvent, and heat treating the polybenzimidazole at a temperature of about 350.degree. to 600.degree. C.

Abstract: A method for manufacturing a low density rubber foamed body is provided which comprises the steps of forming a sheet from a mixture of 100 parts by weight of natural rubber or a synthetic rubber, 10 to 80 parts by weight of a foaming agent, and 0.5 to 15% by weight of a crosslinking agent; enclosing said sheet within a mold and heating said mold under pressure from the exterior to thereby foam said sheet; forcibly cooling said mold; and releasing a foamed body from said mold. When 10 to 60 parts by weight of a thermoplastic synthetic resin are further added to the mixture, a rubber foamed body of still lower density and lower shrinking property is obtained.

Abstract: A foam structure having a density of less than about 20 lbs/ft.sup.3. The method of forming the same comprising forming a homogeneous melt blend under pressure of a polymer member selected from the group consisting of polyetherimide resin particles, polycarbonate resin particles, a polymer blend of polyphenylene oxide and polystyrene in particle form imbibed with a blowing agent, followed by extrusion of the same into a lower pressure atmosphere. A composition comprising said particles imbibed with methylene chloride, chloroform, 1,1,2-trichloroethane or mixtures thereof. A method of thermoforming said foam in sheet form.

Abstract: A bicycle wheel assembly prepared by a process comprising the steps of:(a) Inserting a bicycle rim assembly comprising a central hub, a plurality of radially extending spokes joined to said hub at one end and a rim having a channular cross section joined to the opposed ends of the spokes into a mold cavity configured to form a bicycle tire around the rim;(b) Injecting a foamable polyurethane composition into said mold cavity;(c) Foaming and curing the polyurethane composition in the mold cavity; and(d) Cooling the so-foamed polyurethane composition to cause it to shrink fit around the rim.

Abstract: A foam structure having a density of less than about 20 lbs/ft.sup.3. The method of forming the same comprising forming a homogeneous melt blend under pressure of a polymer member selected from the group consisting of polyetherimide resin particles, polycarbonate resin particles, a polymer blend of polyphenylene oxide and polystyrene in particle form imbibed with a blowing agent, followed by extrusion of the same into a lower pressure atmosphere. A composition comprising said particles imbibed with methylene chloride, chloroform, 1,1,2-trichloroethane or mixtures thereof. A method of thermoforming said foam in sheet form.

Abstract: The present invention relates to an improved nitro urea compound specifically the zinc salt of nitro urea useful as a blowing agent composition, its preparation and its use.

Abstract: A process for making molded flexible polyurethane cellular products which do not substantially shrink or change dimensionally upon cooling is provided by exposing the curing product to atmospheric pressure while in the confines of the mold. Exposure can be accomplished by unlatching the mold or opening a port at an appropriate time after the reaction mixture was introduced into the mold so as to burst the cell walls of the polyurethane product.

Abstract: A medical-surgical dressing comprising a reinforced sheet of silicone elastomer foam having a thickness not exceeding 10 millimeters, one of the surfaces of the sheet having a surface layer of open cell foam and the other surface having a substantially non-cellular surface skin. The dressing may be manufactured by a process comprising depositing a liquid foamable silicone composition on an absorbent surface, allowing the composition to foam and set to an elastomer and thereafter separating the foam sheet from the substrate.The dressings are useful e.g. for the treatment of wounds, burns and as liners for plaster casts.

Abstract: A method for continuously producing an insulation board comprising a rigid plastic foam core having two major surfaces and a facing material on one or both of the major surfaces, the method including conveying a facing material along a production line, depositing a partially expanded froth foam of a plastic mixture, which contains at least one frothing agent, on the facing material, and further expanding and curing the froth foam in contact wiht the facing material to form the insulation board. The board is particularly useful as roof insulation.

Abstract: A molten polymer containing a blowing agent and, usually, a nucleating agent, is spun into fibers with screen packs or equivalent structures upstream of the spinning apertures. The use of screen packs enables the production of fibers with finer bubbles, which are therefore susceptable to greater melt-drawdown and postdrawing and can have better tensile properties. Foamed polyamide fibers are produced with average bubble diameters one-twentieth or less, compared to the effective fiber diameter.

Abstract: Foamed polymers having low loss at microwave frequencies are prepared through use of perfluorinated alkane foaming agents. The invention is particularly valuable for polymers which are melt-processed at high temperatures, especially fluoropolymers such as tetrafluoroethylene copolymers. The polymeric foams are particularly useful as electrical insulation, especially for coaxial cables suitable for use at microwave frequencies.

Abstract: A process for the preparation of an alkenyl aromatic polymeric foam body. The process comprising using water-containing organic vegetable matter as a blowing agent in combination with a volatile fluid foaming agent.

Abstract: The present invention relates to an improved nitro urea compound specifically the zinc salt of nitro urea useful as a blowing agent composition, its preparation and its use.

Abstract: This invention discloses a vinylidene chloride resin type in-mold foam molding having a broad cross-sectional area and a free shape, useful as thermal insulating plate materials or anti-shock molded vessels, and foam particles or expandable particles convenient for preparation thereof, and also a series of advantageous foaming techniques for completion of such a molding. The above foam molding can be prepared by bringing fine particles of a non-crystalline vinylidene chloride type resin obtained generally by suspension polymerization into contact with a volatile organic blowing agent thereby impregnating the resins with the blowing agent to form expandable resin particles, which are in turn subjected to expansion as such, or after forming into pre-expanded foam particles including expandable gas therein, by filling in a mold cavity which can be closed but not sealed, under heating to form a molding through fusion mutually between the expanded particles.

Abstract: A foamed plastic insulator such as an insulated wire having a foamed plastic material insulation layer formed over a conductor. The plastic material includes at least one component having a swelling ratio greater than 55%, and the component comprises at least 20% by weight of the insulation layer. The insulated wire is produced by adding a blowing agent such as a chemical blowing agent and an inert gas and extruding the mixture over a conductor.