The present invention discloses the use of a dry blend comprising a polyethylene resin and a functionalized polyolefin or ionomer in a composition with a thermoplastic resin in order to produce a layer that provides adhesion, fire resistance and low permeation rate in a multi layer rotomolded article.

A method of rotationally molding a large-diameter pipe fitting, the wall structure of which is characterized as having a generally smooth interior surface and an exterior surface that is defined by a plurality of axially-spaced circumferentially extending ribs which are monolithically formed and homogeneous with the smooth interior surface of the fitting. The fitting is seamless and modularly designed with integral coupling elements at each terminal end, and with a ribbed wall structure profile capable of withstanding the loads typically found in buried applications with watertight performance requirements, where such ribbed wall structure meets the following dimensions and dimensional ratios: Rib Sidewall Angle (95-105 degrees); Bottom/Top Rib Thickness Ratio (1.80-2.80); Pitch/Rib Height Ratio (1.50-1.95); Rib Height/Fitting Diameter Ratio (0.04-0.09); and Avg. Rib Thickness/Rib Height Ratio (0.28-0.40).

A method of rotationally molding a large-diameter pipe fitting, the wall structure of which is characterized as having a generally smooth interior surface and an exterior surface that is defined by a plurality of axially-spaced circumferentially extending ribs which are monolithically formed and homogeneous with the smooth interior surface of the fitting. The fitting is seamless and modularly designed with integral coupling elements at each terminal end, and with a ribbed wall structure profile capable of withstanding the loads typically found in buried applications with watertight performance requirements, where such ribbed wall structure meets the following dimensions and dimensional ratios: Rib Sidewall Angle (95-105 degrees); Bottom/Top Rib Thickness Ratio (1.80-2.80); Pitch/Rib Height Ratio (1.50-1.95); Rib Height/Fitting Diameter Ratio (0.04-0.09); and Avg. Rib Thickness/Rib Height Ratio (0.28-0.40).

A method of making a molded article. The method includes introducing into a mold a composition including thermoplastic particles with hollow microspheres attached to their outer surfaces, rotating the mold, and heating the mold at a temperature at which the thermoplastic particles melt. The hollow microspheres are included in the molded article. Molded articles are also disclosed. A powder composition that includes thermoplastic powder particles and hollow ceramic microspheres attached to outer surfaces of at least some of the thermoplastic powder particles is also disclosed. The hollow ceramic microspheres are either adhered to the outer surfaces of at least some of the thermoplastic powder particles with a liquid or embedded in the outer surfaces of at least some of the thermoplastic powder particles.

A method of making a molded article. The method includes introducing into a mold a composition including thermoplastic particles with hollow microspheres attached to their outer surfaces, rotating the mold, and heating the mold at a temperature at which the thermoplastic particles melt. The hollow microspheres are included in the molded article. Molded articles are also disclosed. A powder composition that includes thermoplastic powder particles and hollow ceramic microspheres attached to outer surfaces of at least some of the thermoplastic powder particles is also disclosed. The hollow ceramic microspheres are either adhered to the outer surfaces of at least some of the thermoplastic powder particles with a liquid or embedded in the outer surfaces of at least some of the thermoplastic powder particles.

The present invention relates to a rotomolded article, comprising at least one metallocene-catalyzed polyethylene resin comprising at least two metallocene-catalyzed polyethylene fractions A and B, wherein the polyethylene resin comprises: at least 25% to at most 55% by weight of polyethylene fraction A based on the total weight of the polyethylene resin, wherein fraction A has a melt index MI2 of at least 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg, and a density at least 0.005 g/cm.sup.3 higher than the density of the polyethylene resin; and wherein the polyethylene resin has a density of at least 0.938 g/cm.sup.3 to at most 0.950 g/cm.sup.3 as measured according to ASTM D-1505 at 23° C.; a melt index MI2 of at least 1.0 g/10 min to at most 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg.

The present invention also relates to a process for preparing said rotomolded article.

The present invention relates to a rotomolded article, comprising at least one metallocene-catalyzed polyethylene resin comprising at least two metallocene-catalyzed polyethylene fractions A and B, wherein the polyethylene resin comprises: at least 25% to at most 55% by weight of polyethylene fraction A based on the total weight of the polyethylene resin, wherein fraction A has a melt index MI2 of at least 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg, and a density at least 0.005 g/cm.sup.3 higher than the density of the polyethylene resin; and wherein the polyethylene resin has a density of at least 0.938 g/cm.sup.3 to at most 0.950 g/cm.sup.3 as measured according to ASTM D-1505 at 23° C.; a melt index MI2 of at least 1.0 g/10 min to at most 25.0 g/10 min as determined according to ISO 1133, condition D, at 190° C. and under a load of 2.16 kg.

The present invention also relates to a process for preparing said rotomolded article.

This disclosure relates to rotomolded articles, having a wall structure, where the wall structure contains at least one layer containing an ethylene interpolymer product, or a blend containing an ethylene interpolymer product and an ethylene polymer, where the ethylene interpolymer product has a Dilution Index (Y.sub.d) greater than 0 and improved Environmental Stress Crack Resistance (ESCR). The ethylene interpolymer product has a melt index from about 0.5 to about 15 dg/minute, a density from about 0.930 to about 0.955 g/cm.sup.3, a polydispersity (M.sub.w/M.sub.n) from about 2 to about 6 and a CDBI.sub.50 from about 50% to about 98%. Further, the ethylene interpolymer products are a blend of at least two ethylene interpolymers; where one ethylene interpolymer is produced with a single-site catalyst formulation and at least one ethylene interpolymer is produced with a heterogeneous catalyst formulation.

A vent apparatus for use in a mold defining an opening that includes a vent tube portion configured to extend through the opening of the mold and a secondary tube portion configured to mate with the first end portion of the vent tube portion. For example, the secondary tube portion may be used to seal the passageway at the first end portion and may define one or more membrane regions configured to melt during a mold process to unseal the passageway.

A vent apparatus for use in a mold defining an opening that includes a vent tube portion configured to extend through the opening of the mold and a secondary tube portion configured to mate with the first end portion of the vent tube portion. For example, the secondary tube portion may be used to seal the passageway at the first end portion and may define one or more membrane regions configured to melt during a mold process to unseal the passageway.