Abstract: Polyolefinic particle foams containing additives may be produced by a process, which comprises(a) initially charging a pressure-resistant reactor with a dispersion consisting essentially of polyolefin particles and a liquid dispersion medium, and also a mixture of a volatile organic blowing agent and the additive to be introduced;(b) carrying out a heat treatment in which the polyolefin particles are impregnated with the mixture; and subsequently(c) discharging the dispersion through an orifice into a low-pressure space, thus foaming the polymer particles.The process achieves efficient incorporation of the additives into the polyolefin particles. The particle foams thus-obtained are useful for the production of moldings.

Abstract: When it is intended to obtain foamed particles having a high expansion ratio upon the production of foamed particles of a polyolefin resin, there has been a problem that foamed particles uneven in cell diameter are produced. Any molded article produced with such foamed particles has involved a drawback that it is poor in dimensional stability, and its surface profile becomes uneven.The invention relates to foamed particles comprising a polyolefin resin as a base resin, wherein the base resin contains a metal salt (excluding alkali metal salts) of boric acid in such a manner that the content of the metal salt of boric acid in the raw resin amounts to 50-50,000 ppm. Zinc borate, magnesium borate or the like is used as the metal salt of boric acid.

Abstract: A polyethylene microporous film excellent in mechanical strength, permeability and productivity and having a very high reliability such that the safety of a battery may be secured even under severe circumstances which film has a crosslinked structure and has a porosity of 20-80%, a gel fraction of 1% or more, and an average pore diameter determined by the permeation method of 0.001-0.1 .mu.m, and a process for producing the polyethylene microporous film.

Abstract: Porous polyolefin membrane with a porosity of at least 20%, which is steam sterilizable at elevated temperature, wherein the polyolefin is polyethylene with an intrinsic viscosity of at least 5 dl/g and the membrane shows a shrinkage of at most 4% in every direction in the plane of the membrane when exposed to steam with a temperature of 134.degree. C. for 10 minutes.

Abstract: Foamed articles having enhanced tensile, elastic recovery, and creep and fatigue resistance properties are prepared using a dual cure system. This system comprises a heat or radiation-activated first stage cure (which follows or coincides with foaming) followed by a moisture-activated second stage cure. Heat-activated curing systems include peroxide, sulfur, etc., and radiation-activated cure systems include electron beam, gamma-ray, etc. Moisture-activated systems include silane, sulfonyl chloride, and the like.

Abstract: A nucleator for foaming comprising a fluororesin powder comprising particles having a particle size of 0.1-0.5 .mu.m in a proportion of at least 50% by number and containing particles having a particle size of not less than 5 .mu.m in a proportion of not more than 40% by number, a foamable composition comprising this nucleator and an organic polymer, a foam made therefrom, and a production method of the foam. The nucleator of the present invention can produce a foam made from an organic polymer improved in expansion ratio, fineness of the cells, uniformity of foaming and the like by the use of an extremely small amount thereof. It is preferably used for forming an insulating foam layer of a high frequency coaxial cable.

Abstract: A polymeric composition to be used in producing foam. The polymeric composition comprises a linear low density polyethylene and a resiliency modifier resin. The linear low density polyethylene is in the amount of from about 1 to about 90 weight percent of the polymeric composition. The linear low density polyethylene has a z-average molecular weight, M.sub.z, greater than about 700,000. The resiliency modifier resin is in the amount of from 10 to about 99 weight percent of the polymeric composition. The resiliency modifier resin can be made of a low density polyethylene. Reclaimed material may comprise a portion of the linear low density polyethylene.

Abstract: A propylene-based polymer composition obtained by polymerizing a propylene monomer in the presence of a stereoregular olefin polymerization catalyst system in the first stage to produce a crystalline propylene-based polymer(A) having an intrinsic viscosity of 5 dl/g or more, and successively polymerizing a propylene monomer in the second stage to produce a crystalline propylene-based polymer(B) with an intrinsic viscosity of less than 3 dl/g, wherein the content of the (A) is in the range of 0.05% by weight or more and less than 35% by weight in the total of the polymers(A) and (B), and the total of the polymers(A) and (B) has an intrinsic viscosity of less than 3 dl/g and a Mw/Mn of less than 10, and the foamed article thereof.

Abstract: Compositions and processing conditions are disclosed for the production by rotomolding of polypropylene foams, hither to satisfactorily produced only by injection molding and extrusion molding. Rheological properties of the polypropylene resin, processing conditions and choice of composition of the chemical blowing agent were found to play important roles in obtaining high quality polypropylene foam structures. High strength fine-cell polypropylene foams could in particular be formed by first melt compounding a suitable chemical blowing agent with the resin under conditions which allow for homogeneous mixing without appreciable decomposition of the blowing agent.

Abstract: This invention provides a process for preparing a polyolefin resin foam, comprising the step of extruding to a low-pressure zone a melt of polyolefin resin containing a volatile blowing agent uniformly dispersed therein, the process being characterized in that the volatile blowing agent is a mixture of 5 to 95% by weight of 1,1,1,3,3-pentafluoropropane and 95 to 5% by weight of a low-boiling aliphatic hydrocarbon having a boiling point of 15.degree. C. or lower. According to the invention, there is obtainable a foam of polyolefin resin which is excellent in heat insulating property, dimensional stability and the like and which can retain them for a long term, using a blowing agent which is free of ozone-depleting risks, unlikely to adversely affect global warming, nonflammable and highly compatible with raw materials for foams.

Abstract: A process for preparing super lightweight sheet of the present invention comprises the steps of mixing a low density polyethylene (LDPE), a first blowing agent, a surface activation agent and a separation agent; heating the obtained mixture at a temperature higher than 160.degree. C. to obtain a molten mass; heating said molten mass at a temperature higher than the gasification temperature of said first blowing agent to separate said first blowing agent; cooling the obtained mixture; and forming the cooled mass in a sheet.In a preferred embodiment, the process of the present invention process further comprises the steps of introducing a second gaseous blowing agent in the cooled mass to obtain a foamed mass; maintaining the foamed mass at a stabilizing temperature to stabilize the foamed mass; and cooling the foamed mass at 20-25.degree. C. and maintaining the cooled mass at said temperature for 24 hours.

Abstract: Disclosed herein are foamed and expanded beads of a polypropylene resin for molding, which comprise an uncrosslinked propylene random copolymer having a melting point of at least 140.degree. C. as a base resin, wherein the time required to attenuate an air pressure within the foamed beads applied by a pressurizing treatment with air from 1.2 kgf/cm.sup.2 (G) to 0.8 kgf/cm.sup.2 (G) under atmospheric pressure at 23.degree. C. is at least 80 minutes, and the CNI value of the foamed beads, which is defined by the following equation (1):CNI=log.sub.10 [Pw.times.Er.div.(2.24.times.D.sup.3 .times.B)](1)wherein Pw is an average weight (mg) per foamed bead, Er is a bulk expansion ratio (time) of the foamed beads, D is a cell diameter (mm) of the foamed beads, and B is a density of the base resin, is smaller than 3.80.

Abstract: A foam article is made by (1) irradiating a propylene polymer material selected from the group consisting of (a) a terpolymer of propylene, ethylene, and butene-1, (b) a polyolefin composition that includes (i) about 31% to about 39% of a copolymer of propylene and ethylene, and (ii) about 58% to about 72% of a terpolymer of propylene, ethylene, and butene-1, and (c) a polyolefin composition that includes (i) about 30% to about 65% of a copolymer of propylene and butene-1, and (ii) about 35% to about 70% of a copolymer of propylene and ethylene, and (2) extruding the irradiated propylene polymer material through a die in the presence of a physical expanding agent and a cell nucleating agent, whereby a structure is formed whose density is at least 10.times. less than the initial density of the propylene polymer material. The foam articles exhibit improved flexibility and low temperature toughness compared to conventional propylene polymer materials.

Abstract: A microporous film comprising a high-density polyethylene and a linear copolymer polyethylene and having a terminal vinyl group concentration of 2 or more per 10,000 carbon atoms in the polyethylene, as measured by an infrared spectroscopic method.

Abstract: Porous organic articles having no surface functionality may be treated by remote plasma discharge to thereby introduce functionality to the surface of the article. The functionality is introduced throughout the article's surface, including the exterior surface and the surfaces of the pores. Little or no degradation of the porous organic article occurs as a result of the functionalization. Amino, hydroxyl, carbonyl and carboxyl groups may be introduced to the article. In this way, an essentially inert hydrophobic porous article, made from, for example, polyethylene, can have its surface modified so that the surface becomes hydrophilic. The remote plasma discharge process causes essentially no change in the bulk properties of the organic article. The remote plasma discharge process is preferably conducted so that no photons, and particularly no ultraviolet radiation, is transmitted from the plasma glow to the porous article.

Abstract: This invention relates to a foamed material for fireproofing and/or insulating purposes, consisting of 30 to 90 parts by weight of a solution that contains 20 to 70 wt-% Al (H.sub.2 PO.sub.4).sub.3 and 30 to 80 wt-% water, 5 to 55 parts by weight of a mixture that contains 10 to 70 wt-% MgO, 0 to 70 wt-% mica, 0 to 70 wt-% aluminium hydroxide and 1 to 20 wt-% MnO.sub.2, as well as 1 to 30 parts by weight of a foaming agent that contains 3 to 33 wt-% H.sub.2 O.sub.2 and 67 to 97 wt-% water. In accordance with the invention, the term "insulating purposes" refers to the use of the inventive foamed material for heat and sound insulation.

Abstract: The invention relates to polymer blends which can be used both in foamed and unfoamed states as a replacement for conventional EPDM and other elastomers. The composition of the blend includes a single-site catalyzed polyolefin resin having a density of below 0.878 g cm.sup.-3 and up to 40 weight percent a polyolefin including ethylene and propylene. The polymer blend is cross-linked. The polymer blends are formable and foamable. The use of sulfur to vulcanize the polymer blend is not necessary. The polymer blends can be used to make foam for floatation or for making gaskets.

Abstract: A process additive for polyolefin films and foams produces products having reduced greasiness and reduced grease-like transfer as compared to glycerol monostearate (GMS). The process additive comprises a fatty acid N-aliphatic alcohol amide of the general formula R--CON(R')R". R is a fatty hydrocarbon radical having from about 8 to 30 carbons. R' typically is hydrogen. R' can also be an alkyl radical of from about 1 to 6 carbons or an alkyl alcohol radical of from about 1 to 6 carbons. R" is an alkyl alcohol fragment of from about 1 to 6 carbons. The alkyl alcohol fragments can be monohydric or polyhydric. Secondary fatty monoalkanolamides in which R' is hydrogen are particularly useful, especially stearamide monoethanolamine (MEA). The benefits of the invention can be achieved and enhanced in some examples by mixing the fatty acid N-aliphatic alcohol amide with an ester of a long chain fatty acid with a polyhydric alcohol, including GMS.

Abstract: A process for producing a porous film of polypropylene comprises subjecting (1) an air-impermeable biaxially stretched film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 40% or (2) an air-impermeable inflation film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 46.5%, in the substantial absence of a plasticizer or a solvent, to a thermal treatment in the presence of a first liquid substantially incapable of dissolving the film while fixing the film in two orthogonal directions for making the film porous.

Abstract: A foamed rubber composition for pneumatic tires comprises at least one diene polymer as a rubber ingredient and includes closed cells in a matrix rubber, each of these cells being covered with a coat layer made from a given amount of a resin or resin composite having a JIS-C hardness of not less than 75, a particle size of 10-200 .mu.m and a reacted conjugate diene unit content of not less than 10% by weight. In the production of the foamed rubber composition, the melting point or glass transition point of the resin or resin composite is restricted to at least 5.degree. C. lower than the vulcanizing temperature.

Abstract: There is disclosed a composition which, when cured, results in a foamed product having a low bulk density, said composition comprising:(A) 100 parts by weight of a saturated hydrocarbon polymer containing at least 1.5 alkenyl groups per molecule;(B) 5 to 20 parts by weight of a silicone crosslinker comprising an average of 7 to 50 organohydrogensiloxane units;(C) 1 to 20 parts by weight of water;(D) at least one component selected from the group consisting of(D') 0.1 to 20 parts by weight of an alcohol having 1 to 12 carbon atoms and(D") 5 to 30 parts by weight of a hydrocarbon liquid having a normal boiling point below 100.degree. C.; and(E) a sufficient amount of a hydrosilation catalyst to promote crosslinking of said polymer by said crosslinker.

Abstract: A blow-molded plastic container manufactured from a homogenous mixture of a plastic resin, a calcium carbonate filler, and a blowing agent in specified amounts. The filler reduces the overall material costs, and the blowing agent reduces the specific gravity of the mixture to enable the container to be recycled utilizing existing floatation tank recycling equipment.

Abstract: Catalyst for the polymerization of olefins, process for its preparation, and its use.The present invention relates to a supported catalyst for the polymerization of olefins, which can be prepared by reacting the reaction product formed from an aluminoxane and at least one metallocene with a microporous, polymeric support.

Abstract: New cross-linked polymeric foam compositions, and methods for making the same, are provided. The new compositions utilize novel cross-linked polyolefin copolymers and show improvements in strength, toughness, flexibility, heat resistance and heat-sealing temperature ranges as compared to conventional low density polyethylene compositions. The new compositions also show processing improvements over linear low density polyethylene. The novel polyolefins, which are essentially linear, comprise ethylene polymerized with at least one alpha-unsaturated C3 to C20 olefinic comonomer, and optionally at least one C3 to C20 polyene, and exhibit, in an uncross-linked sense, a resin density in the range of about 0.86 g/cm3 to about 0.96 g/cm3, a melt index in the range of about 0.5 dg/min to about 100 dg/min, a molecular weight distribution in the range of from about 1.5 to about 3.5, and a composition distribution breadth index greater than about 45 percent.

Abstract: Novel molding compositions consisting essentially of a mixture of a skin-forming component and a foam core-foaming component physically dry-blended together. The skin-forming component comprises two distinct phases blended together, a high zero-shear viscosity material and a low zero-shear viscosity material. The foam core-forming component preferably comprises a foamable polymeric material including a suitable blowing agent. In a preferred embodiment, the three materials are selected from suitable homopolymers and copolymers of ethylene.

Abstract: Fine-celled polyolefin foams of high dimensional stability at elevated temperatures and high stiffness, with foam densities ranging from 10 to 600 kg/m.sup.3, consisting of mixtures of polypropylenes and polyolefins, which were reacted with bifunctional, unsaturated monomers and/or hydrolyzable, ethylenically unsaturated organosilane compounds in the presence of thermally decomposing free radical-forming agents in two reactive process steps and subsequently foamed. The fine-celled polyolefin foams are suitable for use in the packaging sector, preferably for packaging foods, for external and internal parts of motor vehicles and for components of electric and electronic equipment.

Abstract: Improved compositions useful for the production of rotomolded articles having a foamed interior and non-foamed exterior skin are provided. The compositions of the invention are comprised of a first thermoplastic resin component which is an ethylene polymer in pellet form containing a chemical foaming agent, an organic peroxide and, optionally, a metal-containing activator compound and a second resin component which is a powder and can be a thermoplastic ethylene polymer or ethylene copolymer having less than 30% crystallinity. An improved one-step process for producing foamed rotomolded articles having foamed interiors and non-foamed exterior skins is also provided.

Abstract: Members either of the polyglycol family of substances, more generally, or of the polyglycol ether subset of polyether compounds, more particularly, both for their gas absorption properties and for their plasticizing effect in a polyethylenic extrudate, are combined with physical atmospheric blowing agents, such as, nitrogen, argon, carbon dioxide, water, and blends thereof, to produce uncrosslinked polyethylenic foams having densities as low as 10 kg/m.sup.3.

Abstract: Highly uniform microporous foam suitable for medical applications and methods for preparing these foams. The highly uniform microporous foams are of controlled pore size that may be utilized in a variety of applications. In preparing the foams, an organic crystalline polymer is melted and combined with a selected solid crystalline fugitive compound to produce a substantially isotropic solution. The solution is cooled under controlled conditions, which foster solid-solid phase separation by the simultaneous crystallization of the fugitive compound and the polymer, to produce a foam precursor containing the solidified fugitive compound dispersed through a matrix of the organic polymer. Crystals of fugitive compound are then removed by solvent extraction and/or sublimation, or like process to produce microcellular foams having a continuous, open-cell structure.

Abstract: In the process and an extrusion device for producing a foamed polymer, a polymer is melted and a foaming agent is added to the polymer melt. After the polymer melt and the foaming agent have been mixed, a throttle generates a pressure drop for nucleation for gas bubbles or cells. The mixture is then shaped, foamed and cooled. In order to produce high-grade foamed polymer with a microcellular or sub-microcellular structure continuously without any shaping limitations, the throttle controlling the flow rate has a passage control so that the flow rate can be adjusted independently of the pressure drop.

Abstract: Disclosed herein are processes for polymerizing ethylene, acyclic olefins, and/or selected cyclic olefins, and optionally selected olefinic esters or carboxylic acids, and other monomers. The polymerizations are catalyzed by selected transition metal compounds, and sometimes other co-catalysts. Since some of the polymerizations exhibit some characteristics of living polymerizations, block copolymers can be readily made. Many of the polymers produced are often novel, particularly in regard to their microstructure, which gives some of them unusual properties. Numerous novel catalysts are disclosed, as well as some novel processes for making them. The polymers made are useful as elastomers, molding resins, in adhesives, etc. Also described herein is the synthesis of linear .alpha.-olefins by the oligomerization of ethylene using as a catalyst system a combination a nickel compound having a selected .alpha.-diimine ligand and a selected Lewis or Bronsted acid, or by contacting selected .alpha.

Abstract: The invention relates to physically-blown low density polyethylene (LDPE) foams that are blends of an LDPE resin and a silane-grafted single-site initiated polyolefin resin. The LDPE resin generally has a density between about 0.91 and about 0.93 g/cm.sup.3 and a melt index greater than 1, and the silane-grafted single-site initiated polyolefin resin generally is a copolymer of ethylene and a C.sub.3 -C.sub.20 alpha-olefin that has a density between about 0.86 and about 0.96 g/cm.sup.3 and a molecular weight distribution between about 1.5 and about 3.5.

Abstract: Biaxially oriented films from high molecular weight polyethylene are characterized by a gas permeable structure formed from random-arranged microfibrils. The films have coefficients of static friction and kinetic friction of not more than 1.0. The biaxially oriented films are further characterized by service smoothness as well as tensile (tangent) modulus and tensile strength. The films may be used for lamination, filter, or for packaging for moisture absorbers. The biaxially oriented films may be obtained by extracting a hydrocarbon plasticizer from a sheet formed from the high molecular weight polyethylene and a hydrocarbon plasticizer, stretching the resulting sheet to obtain an oriented film having a specific surface area of at least 70 m.sup.2 /g and a fibril structure, and heating the oriented film under a standard length constraint to reduce the oriented film in specific area by at least 20 m.sup.2 /g.

Abstract: The disclosed invention is a crystalline microporous polymer and process for preparing a low density microporous polymer comprising, providing a mixture of a polymer and a polymer solvent, the mixture capable of achieving a supercritical condition; applying pressure, at a temperature sufficient for the mixture to attain a super critical condition; cooling the supercritical solution that results and precipitating a microporous crystalline polymer product.

Abstract: An efficient method of producing a microporous polyolefin membrane having improved tensile strength and pierce strength is provided, in which a solution having dissolved therein 5% by weight to 50% by weight of a polyolefin whose weight-average molecular weight is in the range of 5.times.10.sup.5 to 2.5.times.10.sup.6 and whose weight-average molecular weight to number-average molecular weight ratio is less than 10, is extruded and rapidly cooled to obtain a gel-like product which is then stretched and has remaining solvent removed therefrom.

Abstract: A process for preparing an expanded product of a thermoplastic resin which includes a gas dissolving step of adding supercritical carbon dioxide and/or nitrogen as an blowing agent to a thermoplastic resin, and melting it in the thermoplastic resin, a cooling step of cooling the resulting molten resin composition under a pressure not less than a critical pressure of the blowing agent, a nuclei forming step of discharging the molten resin composition from a die to lower the pressure to a level not more than the critical pressure, and an expansion controlling step of cooling an expanded product of the thermoplastic resin to a level not more than a glass transition temperature or a crystallization temperature of the resin to control a cell diameter of the expanded product.

Abstract: Polypropylene films which have cavities distributed in the film and on the surfaces are suitable for writing or printing and have a low density. The films have surface qualities of each side of surface within .+-.2.times.10.sup.-6 inch of the average depth of the cavities, .+-.2% of the average of the gloss at 45.degree. angle and .+-.0.02 of the average of coefficient of friction. Such a film is obtained by passing the molded film from the calender through a set of heating rolls at temperatures revealed in this invention before entering the stretching system. The obtained polypropylene film has superior printability, low density and high stiffness, and thus is suitable for use as a paper substitute.

Abstract: A propylene homopolymer or copolymer, or a blend thereof, possessing both sufficient strain hardening, viscoelastic behavior, and melt ductility is heated, melted, and mixed in an extruder with an organic or inorganic physical blowing agent, or a mixture of organic and inorganic physical blowing agents, and with optional compatibilizing agents, nucleating agents, stabilizers and miscellaneous additives. This mixture is pressurized and, subsequently, is cooled to an appropriate temperature at an elevated pressure, and is extruded through a die at rates in excess of 1000 kg/hr to produce an expanded and dimensionally-stable, predominately closed cell propylene polymer foam with a density of between 10 kg/m.sup.3 and 150 kg/m.sup.3, and with a thickness in excess of 1.3 cm. The resultant foamed structure is characterized by a Foamability Index of greater than 1.9 and an Ebullition Time of less than 2.0.times.10.sup.-4 seconds.

Abstract: An expandable thermoplastic composition is disclosed for extrusion foaming wherein the composition comprises a polyethylene resin and a blowing agent comprising ethane present in an amount of at least about 40 percent or more by weight based upon the total weight of the blowing agent and a different alkane selected from the group consisting of C.sub.1, C.sub.2, C.sub.3, C.sub.4, C.sub.5, and C.sub.6 alkanes and mixtures thereof, wherein the minimum percentage of ethane increases above 40 percent as the arithmetic mean carbon number of the different alkane increases from 3 to 5. A process for extrusion foaming of the composition is also disclosed.

Abstract: A foamed rubber composition for tire comprises a particular amount of particles having specified hardness and average particle size and containing aluminum-bonded hydroxy group and/or silicon-bonded hydroxy group at its surface, and a particular amount of at least one specified silane coupling agent, and develops excellent performances on ice. Further, pneumatic tires contain the foamed rubber composition as a tread rubber.

Abstract: A polyolefin based crosslinked foam excellent in impact absorbability, vibration absorbability and heat insulation, which can be used for various kinds of industrial applications such as materials for the interior of automobiles, cushioning, building, furniture, home use electric appliances, which foam comprises:a polyolefin based resin (A), and a conjugated diene polymer (B) having the peak tan .delta. value (obtained by dynamic viscoelasticity measurement) between -20.degree. C. and 40.degree. C.This invention also relates to a method for manufacturing said impact and vibration absorbable crosslinked foam.The polyolefin based crosslinked foam of this invention is excellent in impact absorbability and vibration absorbability while keeping moldability and heat resistance over a wide range of degrees of crosslinking.

Abstract: Improved compositions useful for the production of foamed rotomolded articles are provided. The compositions of the invention are comprised of a first thermoplastic resin component which is an ethylene polymer in pellet form containing a foaming agent and a second thermoplastic resin component which is a powder consisting of a mixture of different particle size and melt index ethylene polymers. An improved process for producing foamed rotomolded articles having uniformly foamed interiors and smooth exterior skins which are substantially free of surface defects is also provided.

Abstract: A foamed rubber composition for pneumatic tires comprises at least one diene polymer as a rubber ingredient and includes closed cells in a matrix rubber, each of these cells being covered with a coat layer made from a given amount of a resin or resin composite having a JIS-C hardness of not less than 75, a particle size of 10-200 .mu.m and a reacted conjugate diene unit content of not less than 10% by weight. In the production of the foamed rubber composition, the melting point or glass transition point of the resin or resin composite is restricted to at least 5.degree. C. lower than the vulcanizing temperature.

Abstract: In a process for producing polyolefin foam particles, partially foamed particles are produced in a first stage by extrusion of a polyolefin containing solid blowing agents, and these are then further foamed in the second stage using steam.

Abstract: A process for the production of at least one foamed layer of polyolefins comprising: polymerizing a polyolefin elastomer (POE) or polyolefin plastomer (POP) and optionally one or more additional polyolefins with a metallocene catalyst to form a polymerized polyolefin; mixing said polymerized polyolefin, up to 100 parts by weight of a mineral filling material and from 1-10 parts by weight of a chemical propellant based on 100 parts by weight of said polymerized polyolefins to form a sheet layer mixture; rolling said sheet layer mixture on a multiroller calender to produce a sheet layer; heating at least one sheet layer at a temperature above the decomposition point of the chemical propellant so as to foam the sheet layer and form at least one foamed layer. The present invention is also concerned with new coverings which are produced according to this process.

Abstract: The present invention relates to a high-strength porous film or sheet consisting essentially of a high-molecular-weight polyethylene resin having a viscosity-average molecular weight of not less than 300,000, wherein the said film has a thickness of 5 to 50 .mu.m, an air permeability of 200 to 1,000 sec/100 cc, a porosity of 10 to 50% and a pin puncture strength of not less than 600 gf/25 .mu.m, and a process for producing the said film.

Abstract: A stability control agent composition for foamable polyolefin compositions comprising at least one compound that is a partial ester of fatty acid with polyol, and at least one compound selected from the group consisting of higher alkyl amines, fatty acid amides and/or complete esters of higher fatty acids.

Abstract: A water swellable foam matrix formed as a macroporous solid comprising a foam stabilizing agent and a polymer or copolymer of a free radical polymerizable hydrophilic olefin monomer crosslinked with about 0.1 to about 10% by weight of a multiolefin-functional crosslinking agent is described. The foam matrix is characterized by rapid swelling and high water swelling ratios.

Abstract: A process which combines a calender with a stretching system and a set of heating rolls is provided in this invention to produce films of polypropylene resin of wide thickness range. The polypropylene films which have cavities distributed in the film and on the surfaces are suitable for writing or printing and have a low density. The films have surface qualities of each side of surface within .+-.2.times.10.sup.-6 inch of the average depth of the cavities, .+-.2% of the average of the gloss at 45.degree. angle and .+-.0.02 of the average of coefficient of friction. Such a film is obtained by passing the molded film from the calender through a set of heating rolls at temperatures revealed in this invention before entering the stretching system. The obtained polypropylene film has superior printability, low density and high stiffness, and thus is suitable for use as a paper substitute.

Abstract: The molded articles of foamed particles, which are produced by using foamed particles composed of a polypropylene-based polymer, have had excellent cushioning characteristics and impact resilience, but have been not always satisfactory in stiffness such as compressive strength.The invention is directed to foamed particles comprising a polypropylene homopolymer as a base resin and having a tensile modulus of 15,000-25,000 kg/cm.sup.2 and a crystal structure that an inherent peak and a high-temperature peak appear as endothermic peaks on a DSC curve obtained by differential scanning calorimetry of the foamed particles. A quantity of heat at the high-temperature peak is 30-60 J/g.A molded article of foamed particles according to the invention is obtained by using the foamed particles as described above and molding them, and has a density of 0.01-0.3 g/cm.sup.3 and a tensile modulus of 15,000-25,000 kg/cm.sup.2.