Abstract: The present disclosure provides a process for producing low density polyethylene with a dissipation factor less than or equal to 1.48×10?4 radian at 2.47 GHz. The process includes free radical high pressure polymerization of ethylene and separation of the unreacted species from the resultant polyethylene to form a recycle stream. The process further includes purging dissipative components from the recycle stream. The purged recycle stream is then introduced into the polymerization reactor.

Abstract: Process for producing expanded polyolefin resin particles with use as a foaming agent in water contained in an aqueous dispersion medium. The process includes dispersing polyolefin resin particles with use as a foaming agent of water contained in an aqueous dispersion medium. The process includes dispersing polyolefin resin particles together with the aqueous dispersion medium into a closed vessel, heating the polyolefin resin particles up to or above a softening temperature of the polyolefin resin particles and pressurizing the polyolefin resin particles, and releasing the polyolefin resin particles into a zone whose pressure is lower than an internal pressure of the closed vessel. The polyolefin resin particles are composed of a polyolefin resin composition including a polyolefin resin, polyethylene glycol homopolymer and a foam nucleating agent.

Abstract: Expandable composite resin particles for long-term storage, comprising 500 to 5000 ppm of water and 7.5 to 11.0% by weight of pentane in composite resin of polyolefin-based resin and polystyrene-based resin.

Abstract: Polypropylene resin expanded particles comprises a polypropylene resin as a base material resin, the polypropylene resin having at least three melting peaks on a DSC curve for a second temperature rise measured at a heating rate of 10 g/min with use of a heat flux differential scanning calorimeter (DSC), the at least three melting peaks including (i) a lowest temperature melting peak of 100° C. to 130° C. and (ii) a highest temperature melting peak of 140° C. to 160° C., the polypropylene resin having a resin DSC ratio change rate of 0.5%/° C. to 3.0%/° C., the expanded particles having two melting peaks in a DSC measurement made at a first temperature rise at the heating rate of 10 g/min, the two melting peaks including, (i) on a lower temperature side, a melting peak temperature of 100° C. to 130° C. and, (ii) on a higher temperature side, a melting peak temperature of 140° C. to 160° C.

Abstract: A polymeric sheet comprising: a first surface and a second surface; and a first embossed pattern on at least one of the first surface or the second surface and method of preparing same is provided. In one aspect, the sheet comprises at least two protrusions, the at least two protrusions direct, impede, and/or control gas movement between the at least two protrusions when arranged in contact with a surface and externally compressed. In another aspect, the sheet is at least partially cross-linked and/or foamed.

Abstract: In a process for producing polyethylene, ethylene is contacted under polymerization conditions with a slurry of a catalyst composition comprising a particulate support and a Group 4 metal complex of a phenolate ether ligand carried by the support and present in an amount so as to provide about 0.1 to about 35 ???o of Group 4 metal per gram of the support. The resultant polyethylene has a molecular weight of at least 3×105 g/mol as determined by ASTM 4020, an average particle size, d50, of less 300 microns, preferably about 100 to 250 microns, and a span, log10(d90/d10), of less than 0.4.

Abstract: There is provided a polypropylene resin composition comprising a propylene polymer (A) containing 0 to 70% by mass of a propylene homopolymer (A-1) and 30 to 100% by mass of a propylene-ethylene block copolymer (A-2) defined below, an ethylene-?-olefin copolymer (B) defined below, and an inorganic filler (C), wherein the proportion of the amount of the (A), the proportion of the amount of (B), and the proportion of the amount of (C) relative to the total amount of the (A), the (B) and the (C) are 40 to 94% by mass, 5 to 30% by mass, and 1 to 30% by mass, respectively, the propylene-ethylene block copolymer (A-2) is a mixture of a propylene homopolymer component and a propylene-ethylene random copolymer component, wherein the intrinsic viscosity, as measured in Tetralin of 135° C., of the propylene-ethylene random copolymer component is within the range of 2.0 to 8.

Abstract: Thermoplastic compounds are disclosed having functional filler of fly ash particles coupled to the thermoplastic resin via a coupling agent. A coupling agent of functional silane grafts on a backbone of the same polymer or a compatible polymer as the thermoplastic resin causes interaction of the fly ash particles with the thermoplastic resin to enhance physical properties, particularly Notched Izod impact resistance at room temperature and at ?40° C. The coupling interface between the fly ash particle and the coupling agent and the thermoplastic resin is so strong that there can be cohesive failure of the fly ash particle before there is adhesive failure of the fly ash particle from the coupling agent in the thermoplastic resin.

Abstract: A microporous membrane is made by a dry-stretch process and has substantially round shaped pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 5.0. The method of making the foregoing microporous membrane includes the steps of: extruding a polymer into a nonporous precursor, and biaxially stretching the nonporous precursor, the biaxial stretching including a machine direction stretching and a transverse direction stretching, the transverse direction stretching including a simultaneous controlled machine direction relax.

Abstract: A polymer composition for use in the removal and recovery of oil slicks or spills floating on the surfaces of bodies of water or present on land, such as beaches comprising a foam of a blend of polyethylene and an ethylene-alkyl acrylate copolymer and a process for using such foams in the selective removal of oil from fresh water or salt water and the recovery of the absorbed oils from the foams is disclosed. The polymer composition is also for use in other applications in which absorption of liquids is desired.

Abstract: A microporous membrane is made by a dry-stretch process and has substantially round shaped pores and a ratio of machine direction tensile strength to transverse direction tensile strength in the range of 0.5 to 5.0. The method of making the foregoing microporous membrane includes the steps of: extruding a polymer into a nonporous precursor, and biaxially stretching the nonporous precursor, the biaxial stretching including a machine direction stretching and a transverse direction stretching, the transverse direction stretching including a simultaneous controlled machine direction relax.

Abstract: A method of manufacturing a moulded article from expanded resin particles, the method comprising: placing the particles and a dielectric heat transfer fluid in a mould located between a pair of electrodes; generating a radio-frequency electromagnetic field between the electrodes; applying the electromagnetic field to the mould to dielectrically heat the heat transfer fluid and hence the particles; and heating the particles to a temperature sufficient to cause their surfaces to soften, so that the particles fuse, thereby to form the moulded article as shaped by the mould; preferably, wherein the radio-frequency electromagnetic field has a wavelength greater than an average dimension (or dimensions) of the moulded article.

Abstract: Ultra high molecular weight polyethylene (UHMWPE) polymers that have an average molecular weight of at least 500,000 g/mol and an enthalpy of at least 190 J/g is provided. The UHMWPE polymer may include at least one comonomer. The UHMWPE polymer is used to form a membrane, that, when expanded, has a node and fibril structure. The UHMWPE membrane has an endotherm of about 150° C. associated with the fibrils in the membrane. The membrane has a percent porosity of at least 25%, and in exemplary embodiments, the percent porosity is at least 60%. Additionally, the UHMWPE membrane has a thickness less than 1 mm. An UHMWPE membrane may be formed by lubricating the UHMWPE polymer, subjecting the lubricated polymer to pressure at a temperature below the melting point of the UHMWPE polymer to form a tape, and expanding the tape at a temperature below the melting temperature of the UHMWPE polymer.

Abstract: Provided is a method of manufacturing a microporous polyolefin film useable as a battery separator, which is easy to control strength, permeability and shrinking properties of the microporous film and embodies excellent quality uniformity and production stability in fabricating the microporous film.

Abstract: Composite panel, particularly for forming roof panels of cars and/or industrial vehicles, and method of manufacturing the composite panel, which composite panel includes a core of foamed material, at least one skin layer of nonwoven material, and at least one connecting layer between the core of foamed material and the skin layer of nonwoven material.

Abstract: The present invention provides pre-expanded polypropylene resin beads comprising (A) a glycerin monoester of a C6 to C24 fatty acid and/or a polyglycerin monoester of a C6 to C24 fatty acid and (B) a glycerin diester of a C6 to C24 fatty acid(s) and/or a polyglycerin diester of a C6 to C24 fatty acid(s), in such a manner that a weight ratio [=(A)/(B)] between (A) and (B) in the polypropylene resin particles is 1.3 or more but 10 or less, and a total content [=(A)+(B)] is 0.3 parts by weight or more but 5 parts by weight or less with respect to 100 parts by weight of the polypropylene resin. The resin particles can be excellently used in in-mold foaming, without requiring washing with a chemical like nitric acid or metaphosphate soda, and can provide a polypropylene resin in-mold foamed product with good antistatic properties.

Abstract: The disclosure relates, in one aspect, to porous solid-state films with controlled pore structures obtained by laser perforation. A thin laser-perforated film can comprise a slab defining a plurality of pores distributed in a predetermined arrangement, the plurality of pores having a distribution of sizes bound by a predetermined magnitude. In an aspect, the plurality of pores are formed in the slab with a laser having a wavelength less than about 400 nm and the slab has a transmission of the laser light of equal to or less than about 70% measured at a thickness of the slab of 100 micrometer or less.

Abstract: A foam containing 30 to 95% by weight of a polyolefin-based resin and 5 to 70% by weight of a hydrophilizing agent composed of a cellulose-based powder, the surface of the foam being in a melt fractured state.

Abstract: The present application provides a device and methods of making and using these devices. The devices comprise porous caps and porous vents made from sintered porous polymeric media comprising plastic particles, elastomeric particles or a combination thereof. These devices are used with medical devices or components thereof to provide ease of use, resistance to infection, sterilization and venting.

Abstract: Expandable composite resin particles for long-term storage, comprising 500 to 5000 ppm of water and 7.5 to 11.0% by weight of pentane in composite resin of polyolefin-based resin and polystyrene-based resin.

Abstract: In order to obtain a flame-retardant polyolefin resin expanding molded product which has excellent in-mold moldability and excellent surface appearance and satisfies the FMVSS flammability even if carbon black is added, polyolefin resin particles containing, with respect to 100 parts by weight of polyolefin resin, (i) 0.03 part by weight to 5 parts by weight of phosphorous flame retardant having a phosphorous content of 7% by weight or more, a melting point of 120° C. or more, and a 5% by weight decomposition temperature within a range of 240° C. to 320° C. and (ii) 0.5 part by weight to 20 parts by weight of carbon black are expanded.

Abstract: Fibers that are formed from a thermoplastic composition that contains a polymer and high surface area nanostructures are provided. The fibers have a voided structure and low density while maintaining good strength characteristics. To achieve such a structure, a blowing agent in the thermoplastic composition is activated during extrusion to form bubbles in the fibers. The high surface area nanostructures in the formed fibers can be formed of or carry the blowing agent and can enhance the strength of the fibers and compensate for the non-load bearing voids of the fibers.

Abstract: A formulation includes a polymeric material and can be used to form an insulated container.

Abstract: The present invention is concerned with a polypropylene composition comprising a polypropylene base resin, the polypropylene composition having —a XHU content of less than 1.25 wt.-%; —a F30 melt strength of at least 30 cN, determined in the Rheotens test at 200° C.; and —a melt extensibility v30 of at least 200 m/s, determined in the Rheotens test at 200° C. In another aspect the present invention is concerned with a polypropylene composition having an MFR (2.16 kg, 230° C., ISO 1133) of 1.0 to 5.0 g/10 min comprising a polypropylene base resin, the polypropylene base resin being obtainable by producing an intermediate polypropylene having an MFR (2.16 kg, 230° C., ISO 1133) of 0.5 to 2.5 g/10 min in the presence of an asymmetric catalyst; mixing the intermediate polypropylene with peroxide and at least one diene at a temperature of 20 to 90° C.

Abstract: The invention is directed to a masterbatch comprising a nucleating organic compound which, on changing to the solid phase, forms crystals and which in its melt phase is soluble in the molten polyethylene and polyethylene. The ingredients of this masterbatch are applied as a nucleating agent masterbatch during the production of polyethylene foam.

Abstract: Provided are non-crosslinked foamed polyethylene resin particles that have a bulk density BD of 10 g/L or more and 100 g/L or less and are obtained by foaming polyethylene resin particles containing an antistatic agent in an amount of 0.1 part by weight or more and 3 parts by weight or less with respect to 100 parts by weight of a polyethylene resin and having a density of 0.920 g/cm3 or more and less than 0.940 g/cm3, and the non-crosslinked foamed polyethylene resin particles have a shrinkage ratio of 3% or more and 30% or less determined in accordance with Formula (1). The non-crosslinked foamed polyethylene resin particles can simply afford an antistatic molded non-crosslinked foamed polyethylene resin body that has a small shrinkage ratio with respect to mold dimension, is deformed in a small degree, and has good surface stretch.

Abstract: Disclosed are bowing agent compositions, foamable compositions, foams, foaming methods and/or foamed articles comprising one or more C2 to C6 fluoroalkenes, more preferably one or more C3 to C5 fluoroalkenes, and even more preferably one or more compounds having Formula I as follows: XCFzR3-z??(I) where X is a C1, C2, C3, C4, or C5 unsaturated, substituted or unsubstituted radical, each R is independently Cl, F, Br, I or H, and z is 1 to 3, it generally being preferred that the fluoroalkene of the present invention has at least four (4) halogen substituents, at least three of which are F and even more preferably none of which are Br.

Abstract: The present invention relates to a foamed polypropylene composition comprising a propylene homo- and/or copolymer and glass fibres, wherein (i) the composition has a density of 50 to 950 kg/m3, (ii) the tensile modulus tm(extrusion direction) measured according to ISO 527 in extrusion direction and the k-value measured according to ASTM C-518 satisfy the relation: tm(extrusion direction) [MPa]/k [W/mK]?9000 MPa·mK/W, to the use of said composition for the production of an insulating layer and to an article comprising said composition.

Abstract: In accordance with at least selected embodiments, the present invention is directed to novel, improved, or modified porous membranes, fibers, porous fibers, products made from such membranes, fibers or porous fibers, and/or related methods of production, use, and/or the like. In accordance with at least certain embodiments, the present invention is directed to novel, improved, or modified microporous membranes or films, fibers, microporous fibers, materials or layers made from such membranes, fibers or porous fibers, and the like for use in textile materials, garments, products, and/or textile related applications. Microporous membranes, fibers, and/or microporous fibers are made of one or more copolymers, such as block or impact copolymers, or of at least one polyolefin combined with at least one copolymer as a means of improving the hand, drape, and/or surface coefficient of friction performance properties for use in textile garments, textile materials or textile related applications.

Abstract: Disclosed are compositions useful in a wide variety of applications, including heat transfer fluids which possess a highly desirable and unexpectedly superior combination of properties, and heat transfer systems and methods based on these fluids. The preferred heat transfer fluid comprises from about 1 to about 40 percent, on a weight basis, of carbon dioxide (CO2) and from about 99 to about 60 percent, on a weight basis, of a compound having the Formula I XCFzR3-z (I), where X is a C2 or a C3 unsaturated, substituted or unsubstituted, alkyl radical, each R is independently Cl, F, Br, I or H, and z is 1 to 3. A preferred compound of Formula I is tetrafluoropropene, particularly 1,1,1,3-tetrafluoropropene and/or 1,1,1,3-tetrafluoropropene.

Abstract: The invention provides a composition comprising a low density polyethylene (LDPE) obtained by free radical polymerization of ethylene, and wherein the LDPE has a GPC-Viscometer parameter “DPP” less than 1.3. The invention also provides a composition comprising an ethylene-based polymer that comprises the following features: a) at least 0.1 amyl groups per 1000 total carbon atoms; b) a melt index from 0.5 to 0.9 c) a MWD(conv) [Mw(conv)/Mn(conv))] from 9 to 13; The invention also provides a composition comprising an ethylene-based polymer that comprises the following features: a) at least 0.1 amyl groups per 1000 total carbon atoms; b) a MWD(conv) from 9 to 13; c) a gpcBR value from 2.0 to 5.0; d) a melt strength (MS) greater than 20 cN.

Abstract: Olefin polymer-based, durable, open-cell foam compositions, structures and articles derived from same; methods for preparation of such foams; and use of the dry durable foams in various applications are disclosed. Further described is use of the foams and structures and articles made of same in absorption, filtration, insulation, cushioning and backing applications, and in particular for odor removal, hygiene and medical applications due to, among other properties, good absorption capabilities, softness and/or flexibility of the foams and their recyclable nature.

Abstract: Provided is a porous polypropylene film having both air permeability properties and puncture strength. A porous polypropylene film which has an air permeability of 700 seconds/100 ml or less and a puncture strength of 1.5 N or greater, and has ? activity can be obtained when the porous polypropylene film is made to have a tensile strength in the machine direction of the film, EMD, of 100 MPa or greater, a tensile strength in the transverse direction to the machine direction, ETD, of less than 100 MPa, and a ratio of EMD and ETD, EMD/ETD, of 1.5 to 10.

Abstract: Provided is a porous polypropylene film having both air permeability properties and puncture strength. A porous polypropylene film which has an air permeability of 700 seconds/100 ml or less and a puncture strength of 1.5 N or greater, and has ? activity can be obtained when the porous polypropylene film is made to have a tensile strength in the machine direction of the film, EMD, of 100 MPa or greater, a tensile strength in the transverse direction to the machine direction, ETD, of less than 100 MPa, and a ratio of EMD and ETD, EMD/ETD, of 1.5 to 10.

Abstract: To provide a thermoplastic resin microporous film being difficult in longitudinal tearing and excellent in tear resistance; a microporous film comprising a thermoplastic resin, wherein a melt flow rate of the thermoplastic resin in the microporous film is in the range of 0.1 to 2.0 g/10 min, tensile strength in a cross-machine direction is in the range of 5 to 10 MPa and tensile elongation in the cross-machine direction is 300% or more.

Abstract: Solid state draw a polymer billet, wherein at least 50 percent of all polymers in the billet is a continuous phase of polyethylene polymer having a density of 0.941-0.959 grams per cubic centimeter and a weight-average molecular weight that is 110,000 grams per mole or greater, at a drawing rate of 1.2 meters per minute or faster using a tensile force to create an oriented and cavitated polymer composition whose cross section dimensions all exceed two millimeters.

Abstract: A molded polyethylene component that comprises polyethylene having a melt flow index of about 3.5 g/10 min or greater as measured by ASTM D1238 at 190° C./21.5 kg weight and having an ash content of about 500 ppm or less may be useful biomedical devices, including kits and methods relating thereto.

Abstract: The present invention features hydrophilic IR-transparent porous membranes, particularly hydrophilic IR-transparent porous polyethylene membranes and methods of preparing the hydrophilic membranes by treatment of hydrophobic IR-transparent porous membranes with plasma. The present invention further features spectroscopic sample holders which incorporate the hydrophilic IR-transparent porous membranes and methods of identifying bacteria and other microorganisms in samples by infrared spectroscopy.

Abstract: The presently disclosed subject matter relates generally to method of producing thermoplastic foam from a blend of polyolefin and acrylated epoxidized fatty acid using a phsyical blowing agent. Specifically, the presently disclosed subject matter includes embodiments wherein the acrylated epoxidized fatty acid is added to the polyolefin resin in an amount of from about 0.1% to about 10%, based on the total weight of the resin. The presently disclosed subject matter also includes the foam produced by the disclosed method.

Abstract: There are disclosed additive compositions for polymer base materials, which additive compositions are comprised of blowing agent (direct gas or chemical blowing agent), thermoplastic polymer carrier for the chemical blowing agent and filler, wherein the thermoplastic polymer carrier has a melting point below the decomposition temperature of the chemical blowing agent. The chemical blowing agent can be selected from those based on hydrazine, hydrazide, or azodicarbonamide, or those based on combinations of sodium citrate/citric acid and sodium bicarbonate. The filler can be selected from calcium carbonate, zeolites, clay and other known fillers. The polymer base sheet material can be, e.g., polyethylene, polypropylene, polybutylene, poly (p-phenylene oxide), polystyrene and combinations thereof. If direct gas blowing agent is used, then the compositions should contain a nucleating agent which may or not be the same as the chemical blowing agent.

Abstract: Disclosed are compositions comprising antioxidants and stabilizers, such as, acid scavengers or organic phosphorus stabilizers, and optionally further comprising co-stabilizers. The disclosed compositions are useful as stabilizers for polyolefins and other polymeric materials. The disclosed compositions and methods generally provide longer shelf lifes and better oxidative resistance to materials than currently available antioxidants.

Abstract: To be provided is a foam waterproofing material superior in waterproofness and flexible enough to be compatible with further minute clearance. The foam waterproofing material according to the present invention is a waterproofing material including a foam having a thickness of 0.1 to 1.0 mm, characterized in that the foam has a micro cell structure with an average cell diameter of 10 to 60 ?m and an apparent density of 0.01 to 0.060 g/cm3. In the foam waterproofing material, the repulsive load when compressed to 0.1 mm (0.1 mm-compressive repulsion force) of the foam is preferably 0.01 to 0.1 MPa. The foam preferably has a closed-cell structure or a semi-open- and semi-closed-cell structure. In addition, the foam may have a pressure-sensitive adhesive layer on one or both faces thereof. The pressure-sensitive adhesive layer is preferably formed on the foam via a film layer.

Abstract: The present invention provides a highly functional polyethylene fiber exhibiting reduction of change in their physical properties in a wide range of temperatures for processing for products and in a wide range of temperatures for usage as products, thereby enabling improvement of dimensional stability. In addition, the present invention provides a highly functional polyethylene fiber exhibiting a high degree of dye exhaustion to be obtained in a simple dyeing operation, and excellent color fastness. The highly functional polyethylene fiber of the present invention is characterized in that an intrinsic viscosity [?] is higher than or equal to 0.8 dL/g, and not higher than 4.9 dL/g, ethylene is substantially contained as a repeating unit thereof, and a maximum thermal shrinkage stress is less than or equal to 0.4 cN/dtex in TMA (thermo-mechanical analysis), and a thermal shrinking percentage at 100° C. is less than or equal to 2.5%.

Abstract: A polyethylene powder is described having a molecular weight in the range of from 3,000,000 g/mol to less than 4,000,000 g/mol as determined by ASTM 4020 and a bulk density of 0.10 to 0.20 g/cm3. On sintering, the polyethylene powder produces a porous article having an elastic modulus of at least 90 MPa.

Abstract: Provided are pre-expanded polypropylene resin particles having a dimensional expansion coefficient of 1.5% or more determined with a thermomechanical analyzer at a constant compressive load of 1 mg during heating from 30° C. to 100° C. at a temperature increase rate of 10° C./min. Using the pre-expanded polypropylene resin particles can yield an in-mold foam molded product of polypropylene resin having few wrinkles and small dimensional shrinkage without pretreatment such as internal pressure application or compression packing during packing the pre-expanded particles in a mold for in-mold foam molding.

Abstract: The present invention relates to a flame-retardant composition that comprises a synergistic flame-retardant mixture, and a method for flame-retarding a polymer by adding the flame-retardant composition. The invention further relates to polymers that contain said flame-retardant composition.

Abstract: A coating composition has a natural fibre-bearing dry matter mixture, as well as cellular plastic grains, mixed into water. By spreading this composition onto any base, particularly by spraying, and by hardening it, particularly through drying, the coating is formed from the coating composition, which coating provides extremely good acoustic properties. If a special fibre base plate based on chemical pulp is used as the base of the coating, the plate-like acoustic element is obtained.

Abstract: Provided are (i) polyethylene resin foamed particles which are obtained by foaming polyethylene resin particles to be foamed having good productivity and a high expansion ratio and which are suppressed in reduction of cell diameters, and (ii) a polyethylene resin in-mold foam molded article obtained from the polyethylene resin foamed particles which has good surface smoothness while being reduced in surface yellowing. The polyethylene resin foamed particles (i) contain, as a base resin, a polyethylene resin composition containing, in an amount of not less than 1000 ppm to not more than 4000 ppm in total, one or more compounds selected from the group consisting of antioxidants, metal stearates, and inorganic substances and (ii) have Z-average molecular weight of not less than 40×104 to not more than 70×104, an average cell diameter of not less than 180 ?m to not more than 450 ?m, and an open-cell ratio of not more than 12%.

Abstract: The Broadhead Block is comprised of a closed cell, cross linked, polyethylene foam. The block is cut in the form of a cube that can be held in one's hand while being used. It has multiple sides to allow a number of objects to be secured into each side as desired. The closed cell construction of the polyethylene allows for continued penetrations with a long lasting durability. Thus providing means to loosen or tighten broad heads on the shaft of the arrow, while acting as a protective shield from the sharp blades. It acts as a wrench allowing one to grip the block instead of the sharp or broken broad heads while performing either installation or removal of said blades or broad head points from arrows.

Abstract: Provided are polypropylene resin pre-foamed particles including, as base resin, polypropylene resin that satisfies the following requirements (a) through (c): (a) in cross fractionation chromatography, an amount of components eluted at a temperature of not more than 40° C. is not more than 2.0% by weight; (b) a melting point is not less than 100° C. but not more than 160° C.; and (c) propylene monomer units are present in an amount of not less than 90 mol % but not more than 100 mol %, and olefin units each having a carbon number of 2 or 4 or more are present in an amount of not less than 0 mol % but not more than 10 mol %. The polypropylene resin pre-foamed particles can be molded by in-mold foaming molding at a not high molding heating steam pressure, and a polypropylene resin in-mold foaming molded product excellent in dimensional stability at high temperatures can be prepared from the polypropylene resin pre-foamed particles.