A molded article of polyolefin-based resin expanded beads having excellent appearance and further suppressed color unevenness is provided.

Polyolefin-based resin expanded beads obtained by expanding polyolefin-based resin particles including one or two or more metal borates selected from zinc borate and magnesium borate, wherein the particles of the metal borate has an arithmetic average particle diameter based on the number of 1 μm or more, and a number rate of the particles of the metal borate having a particle diameter of 5 μm or more is 20% or less. A method for producing polyolefin-based resin expanded beads by releasing expandable polyolefin-based resin particles containing one or two or more metal borates selected from zinc borate and magnesium borate and a physical blowing agent dispersed in an aqueous medium in a closed vessel together with the aqueous medium from the closed vessel to a low pressure region than an inside of the closed vessel to expand the expandable polyolefin-based resin particles, the method comprising: using a metal borate having an arithmetic average particle diameter based on the number of 1 μm or more and a number rate of the particles having a particle diameter of 5 μm or more of 20% or less as the metal borate.

Expanded polypropylene resin particles include a polypropylene resin as a base material resin, wherein the polypropylene resin has a flexural modulus of 750 MPa to 1100 MPa. The flexural modulus and a melting point of the expanded polypropylene resin particles satisfy Expression (1): [Flexural modulus (MPa)]<31.19×[Melting point (° C.)]−3500, wherein the melting point of the expanded polypropylene resin particles is a melting point of 141.5° C. to 150.0° C. in a second differential scanning calorimetry (DSC) curve of a second temperature increase, the second DSC curve being obtained when the expanded polypropylene resin particles are heated from 40° C. to 220° C. at a temperature increase rate of 10° C./min in a first temperature increase, then cooled from 220° C. to 40° C. at a temperature decrease rate of 10° C./min, and heated again from 40° C. to 220° C. at a temperature increase rate of 10° C./min in the second temperature increase.

Expanded polyethylene resin particles include an antistatic agent and a base resin. The expanded polyethylene resin particles are obtained by expanding polyethylene resin particles including the antistatic agent and the base resin, the polyethylene resin particles having a storage modulus of elasticity of 900 to 5000 Pa at an angular frequency of 1 rad/sec in dynamic viscoelastic behavior measurement at 190° C. and a storage modulus of elasticity of 100000 Pa or less at an angular frequency of 100 rad/sec in dynamic viscoelastic behavior measurement at 190° C. The expanded polyethylene resin particles have a low temperature side melting peak and a high temperature side melting peak on a differential scanning calorimetry (DSC) curve obtained when a temperature of the expanded polyethylene resin particles is increased from 20° C. to 220° C. at a heating rate of 10° C./min.

Expanded polyethylene resin particles include an antistatic agent and a base resin. The expanded polyethylene resin particles are obtained by expanding polyethylene resin particles including the antistatic agent and the base resin, the polyethylene resin particles having a storage modulus of elasticity of 900 to 5000 Pa at an angular frequency of 1 rad/sec in dynamic viscoelastic behavior measurement at 190° C. and a storage modulus of elasticity of 100000 Pa or less at an angular frequency of 100 rad/sec in dynamic viscoelastic behavior measurement at 190° C. The expanded polyethylene resin particles have a low temperature side melting peak and a high temperature side melting peak on a differential scanning calorimetry (DSC) curve obtained when a temperature of the expanded polyethylene resin particles is increased from 20° C. to 220° C. at a heating rate of 10° C./min.

A method of producing a polyethylene resin expanded molded product includes filling a mold with expanded polyethylene resin particles, wherein an internal pressure of 0.12 to 0.16 MPa is applied to the expanded polyethylene resin particles in the mold, and forming the polyethylene resin expanded molded product by heating the expanded polyethylene resin particles and fusing the expanded polyethylene resin particles. The expanded polyethylene resin particles includes 100 parts by weight of a polyethylene resin, 0.08 to 0.25 parts by weight of a cell nucleating agent, 0.3 to 0.8 parts by weight of a polyhydric alcohol fatty acid ester, and 0.01 to 10 parts by weight of a hydrophilic compound, each of the expanded polyethylene resin particles having a weight of 2.5 to 3.5 mg. The polyethylene resin expanded molded product has a density of 0.017 to 0.021 g/cm.sup.3 and a thickness of 10 to 40 mm.

The present disclosure relates to thermoplastic polymeric microspheres comprising a thermoplastic polymer shell surrounding a hollow core, in which the thermoplastic polymer shell comprises a copolymer of a monomer of Formula 1:

##STR00001##

wherein: each of A.sup.1 to A.sup.11 are independently selected from H and C.sub.1 to C.sub.4 alkyl, in which each C.sub.1-4 alkyl group can optionally be substituted with one or more substituents selected from halogen, hydroxy and C.sub.1-4 alkoxy; A.sup.12 is selected from C.sub.1 to C.sub.4 alkyl, in which the C.sub.1-4 alkyl group can optionally be substituted with one or more substituents selected from halogen, hydroxy and C.sub.1-4 alkoxy X is a linking group selected from —O—, —NR″—, —S—, —OC(O)—, —NR″C(O)—, —SC(O)—, —C(O)O—, —C(O)NR″—, and —C(O)S—; and
R″ is H or C.sub.1-2 alkyl optionally substituted with one or more substituents selected from halogen and hydroxyl.

The present disclosure relates to thermoplastic polymeric microspheres comprising a thermoplastic polymer shell surrounding a hollow core, in which the thermoplastic polymer shell comprises a copolymer of a monomer of Formula 1:

##STR00001##

wherein: each of A.sup.1 to A.sup.11 are independently selected from H and C.sub.1 to C.sub.4 alkyl, in which each C.sub.1-4 alkyl group can optionally be substituted with one or more substituents selected from halogen, hydroxy and C.sub.1-4 alkoxy; A.sup.12 is selected from C.sub.1 to C.sub.4 alkyl, in which the C.sub.1-4 alkyl group can optionally be substituted with one or more substituents selected from halogen, hydroxy and C.sub.1-4 alkoxy X is a linking group selected from —O—, —NR″—, —S—, —OC(O)—, —NR″C(O)—, —SC(O)—, —C(O)O—, —C(O)NR″—, and —C(O)S—; and
R″ is H or C.sub.1-2 alkyl optionally substituted with one or more substituents selected from halogen and hydroxyl.

A method of making molded foam articles and the articles produced. A molded foam article is produced by heating or preheating the mold to a temperature at or above the glass transition or melt temperature of the particles to be molded. Foamed particles are then introduced into the mold. The particle filled mold is then subjected to a vacuum to stabilize the molded article, without application of any additional heating or cooling. The molded article is then removed from the mold at a temperature at or below the glass transition temperature of the particles, and the cycle repeated to form multiple molded articles.

A method of making molded foam articles and the articles produced. A molded foam article is produced by heating or preheating the mold to a temperature at or above the glass transition or melt temperature of the particles to be molded. Foamed particles are then introduced into the mold. The particle filled mold is then subjected to a vacuum to stabilize the molded article, without application of any additional heating or cooling. The molded article is then removed from the mold at a temperature at or below the glass transition temperature of the particles, and the cycle repeated to form multiple molded articles.

A footwear article is provided. The footwear article includes a shoe sole. The shoe sole includes a crosslinked foam polyolefin elastomer having a density less than 0.88 g/cm.sup.3, the crosslinked foam polyolefin elastomer including: a silane-grafted polyolefin elastomer, a silane-grafted olefin block copolymer, a polyolefin elastomer (POE), an olefin block copolymer (OBC), or a combination thereof; an ethylene vinyl acetate (EVA) copolymer; a crosslinker; a condensation catalyst; and a foaming agent. The shoe sole exhibits a compression set of from about 1.0% to about 50.0%, as measured according to ASTM D 395 (48 hrs @ 50° C.).