Patents by Inventor Pak-Wing S. Chum

Pak-Wing S. Chum has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6087447
    Abstract: Blends of polymeric materials comprising (A) from about 1 to about 99 weight percent of at least one interpolymer containing (1) from about 1 to about 65 mole percent of (a) at least one vinylidene aromatic monomer, or (b) at least one hindered aliphatic vinylidene monomer, or (c) a combination of at least one vinylidene aromatic monomer and at least one hindered aliphatic vinylidene monomer, and (2) from about 35 to about 99 mole percent of at least one aliphatic .alpha.-olefin having from 2 to about 20 carbon atoms; and (B) from about 1 to about 99 weight percent of at least one homopolymer or interpolymer of one or more vinylidene aromatic monomers and/or one or more hindered aliphatic vinylidene monomers. These blends have been observed to possess improved properties when compared to the individual polymers comprising the blend and to provide materials with enhanced processability and temperature ranges of performance.
    Type: Grant
    Filed: March 5, 1998
    Date of Patent: July 11, 2000
    Assignee: The Dow Chemical Company
    Inventors: James C. Stevens, Francis J. Timmers, Martin J. Guest, John J. Gathers, Yunwa W. Cheung, Pak-Wing S. Chum, Chung P. Park, George P. Clingerman, Kevin D. Sikkema
  • Patent number: 6015617
    Abstract: The subject invention is directed to polymer compositions having improved bond performance, to a method for improving the bond performance of a polymer composition, and to fabricated articles, such as fibers and fabrics which exhibit an improved bond performance, and to other fabricated articles, including but not limited to rotationally molded articles, prepared from polymer compositions of the invention.
    Type: Grant
    Filed: June 5, 1998
    Date of Patent: January 18, 2000
    Assignee: The Dow Chemical Company
    Inventors: Rexford A. Maugans, Ed N. Knickerbocker, Rebecca J. Sawchuk, Alan R. Whetten, Ronald P. Markovich, Pak-Wing S. Chum
  • Patent number: 6005053
    Abstract: Polymer mixtures are disclosed which comprise at least one homogeneously branched ethylene polymer (A) and at least one ethylene polymer (B) having a crystallinity which is at least 7% greater than the crystallinity of polymer (A) with certain provisos. A process for making a molded article using the disclosed polymer mixtures is disclosed as well as films, film layers, coatings and molded articles formed from those mixtures. These mixtures have several advantages over polymer compositions of the prior art, including improved properties at elevated temperatures such as improved softening point under load, improved hardness, improved toughness, improved 100% modulus of elasticity, improved compression set, improved ability to prevent oil bleed out at lower temperatures when the mixture contains oil and reduced injection molding cycle time. The mixtures retain their performance advantages even when substantial amounts of additives such as oil and filler are incorporated into the mixture.
    Type: Grant
    Filed: January 22, 1997
    Date of Patent: December 21, 1999
    Assignee: The Dow Chemical Company
    Inventors: Deepak R. Parikh, Pak-Wing S. Chum, Rajen M. Patel, Klye G. Kummer, Pradeep Jain, Thomas J. McKeand, Jr., Ronald P. Markovich, Timothy E. Clayfield, Wasif Ahmed Khan
  • Patent number: 5874139
    Abstract: The subject invention generally provides a multilayer structure that includes a polymer mixture made from at least two polymer component materials. The invention particularly pertains to a multilayer structure containing an improved sealant layer and a polypropylene layer, wherein the sealant layer is made from a homogeneously branched ethylene polymer having particular molecular weight characteristics and a second ethylene polymer. The sealant layer has balanced properties such low heat seal and hot tack initiation temperature, a high hot tack strength and a broad hot tack seal window. The multilayer structure is particularly useful as a biaxially oriented polypropylene (BOPP) packaging film structure.
    Type: Grant
    Filed: November 13, 1996
    Date of Patent: February 23, 1999
    Assignee: The Dow Chemical Company
    Inventors: Luc Bosiers, Jacquelyn A. deGroot, Lawrence T. Kale, Pak-Wing S. Chum
  • Patent number: 5595705
    Abstract: A method of manufacturing a monolayer heat-shrinkable, puncture-resistant biaxially oriented film is disclosed. The method includes a double bubble orientation step and extruding a primary tube that includes at least one substantially linear ethylene homopolymer or interpolymer, wherein the substantially linear ethylene homopolymer or interpolymer has an uniform branching distribution, a melt flow ratio I.sub.10 /I.sub.2, .gtoreq.5.63, and a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and is also characterized as having essentially no linear polymer fraction, a single DSC melting peak, a density greater than about 0.85 g/cc, and a favorable gas extrusion critical shear rate at the onset of surface melt fracture.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: January 21, 1997
    Assignee: The Dow Chemical Company
    Inventors: Kim L. Walton, Rajen M. Patel, Pak-Wing S. Chum, Todd J. Obijeski
  • Patent number: 5591390
    Abstract: A method of manufacturing a multilayer heat-shrinkable, puncture-resistant biaxially oriented film is disclosed. The method includes a double bubble orientation step and extruding a primary tube that includes at least one substantially linear ethylene homopolymer or interpolymer, wherein the substantially linear ethylene homopolymer or interpolymer has an uniform branching distribution, a melt flow ratio, I.sub.10 /I.sub.2,.gtoreq.5.63, and a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and is also characterized as having essentially no linear polymer fraction, a single DSC melting peak, a density greater than about 0.85 g/cc, and a favorable gas extrusion critical shear rate at the onset of surface melt fracture.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: January 7, 1997
    Assignee: The Dow Chemical Company
    Inventors: Kim L. Walton, Rajen M. Patel, Pak-Wing S. Chum, Todd J. Obijeski
  • Patent number: 5589128
    Abstract: Super high flow ethylene polymer compositions comprising at least one linear ethylene polymer are disclosed which have improved processability for use in making thermally formed articles (e.g., thin-walled lids, cups and containers). The compositions have a processing index from about 0.005 KPoise to about 1 KPoise and are particularly useful in thermal forming processes having shear rates of at least 2,000 sec.sup.-1 (e.g., injection molding processes). The compositions can be used to make thin-walled lids and cups and have good environmental stress crack resistance and Gullwing Tear properties.
    Type: Grant
    Filed: August 12, 1994
    Date of Patent: December 31, 1996
    Assignee: The Dow Chemical Company
    Inventors: Shih-Yaw Lai, Lonnie G. Hazlitt, Pak-Wing S. Chum
  • Patent number: 5562958
    Abstract: Biaxially oriented, heat-shrinkable film-making process and film with improved toughness and extrusion processibility are disclosed. The improved film comprises at least one layer of at least one substantially linear ethylene homopolymer or interpolymer, wherein the substantially linear ethylene polymer has an uniform branching distribution, and is also characterized as having essentially no linear polymer fraction, a single DSC melting peak, a density greater than about 0.85 g/cc, and a simple bubble film 1% secant modulus below 195,000 kPa. The biaxially oriented film is characterized as having a simple bubble shrinkage value of from about 18% to about 85% at 135.degree. C. and is useful in preparing heat-shrink bags for packaging food articles like poultry and fresh red meat.
    Type: Grant
    Filed: April 28, 1993
    Date of Patent: October 8, 1996
    Assignee: The Dow Chemical Company
    Inventors: Kim L. Walton, Rajen M. Patel, Pak-Wing S. Chum, Todd J. Obijeski
  • Patent number: 5487938
    Abstract: A transition metal containing catalyst useful for the polymerization of .alpha.-olefins is prepared by (A) forming in an inert atmosphere which excludes oxygen and moisture a slurry of (1) a porous inorganic oxide support material selected from the group consisting of silica, alumina, or a combination of silica and alumina, said support material containing not greater than about 5 millimoles of hydroxyl groups per gram of support material and a particle size not greater than about 10 microns and a surface area of from about 50 to about 800 m.sup.2 /g in an inert organic liquid medium; (B) mixing said slurry with (2) an alkoxide and stirring the resultant mixture at a temperature of from about -20.degree. C. to about 120.degree. C. for a time sufficient to saturate the surface of the support material; (C) mixing the product form (B) with (3) a titanium compound or a combination of a titanium compound and (4) a vanadium compound and stirring the resultant mixture at a temperature of from about -20.degree. C.
    Type: Grant
    Filed: November 10, 1994
    Date of Patent: January 30, 1996
    Assignee: The Dow Chemical Company
    Inventors: Lee Spencer, Brian W. S. Kolthammer, Miriam P. Ripplinger, Jeffrey J. Wooster, Pak-Wing S. Chum, Jacquelyn A. deGroot
  • Patent number: 5427807
    Abstract: Food products, especially fresh food products such as retail-cut red meat, vegetables and fruits, are packaged with a film having at least one film layer comprising a substantially linear ethylene polymer, preferably a polymer comprising ethylene and at least one .alpha.-olefin comonomer, e.g. 1-octene. The ethylene polymers used in the construction of the film structures used in this invention are prepared by constrained geometry catalyst technology. The film structures can be either mono- or multilayered, oriented or nonoriented, oxygen permeable or impermeable, and prepared by any conventional technique. The food products can be packaged by any conventional method, e.g. stretch overwrap, shrink, vacuum skin, on vacuum forming.
    Type: Grant
    Filed: April 26, 1993
    Date of Patent: June 27, 1995
    Assignee: The Dow Chemical Company
    Inventors: Pak-Wing S. Chum, Nicole F. Whiteman
  • Patent number: 5407965
    Abstract: Disclosed is a cross-linked ethylenic polymer foam structure of an ethylenic polymer material of a cross-linked, substantially linear ethylenic polymer. The substantially linear ethylenic polymer having in an uncross-linked state has: a) a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63; b) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation: M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63; and c) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear ethylenic polymer having about the same I.sub.2 and M.sub.w /M.sub.n. Further disclosed is a process for making the above foam structure.
    Type: Grant
    Filed: August 24, 1994
    Date of Patent: April 18, 1995
    Assignee: The Dow Chemical Company
    Inventors: Chung P. Park, Pak-Wing S. Chum, George W. Knight
  • Patent number: 5387620
    Abstract: Disclosed is a cross-linked ethylenic polymer foam structure of an ethylenic polymer material of a cross-linked, substantially linear ethylenic polymer. The substantially linear ethylenic polymer having in an uncross-linked state has: a) a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63; b) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation: M.sub.w /M.sub.n <(I.sub.10 /I.sub.2)-4.63; and c) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear ethylenic polymer having about the same I.sub.2 and M.sub.w /M.sub.n. Further disclosed is a process for making the above foam structure.
    Type: Grant
    Filed: June 1, 1994
    Date of Patent: February 7, 1995
    Assignee: The Dow Chemical Company
    Inventors: Chung P. Park, Pak-Wing S. Chum, George W. Knight
  • Patent number: 5370940
    Abstract: Film having good blocking properties and low coefficient of friction is prepared without the presence of antiblock additives from certain thermoplastic ethylene interpolymer products. The thermoplastic ethylene interpolymer products have a density of about 0,935 g/ml or less, a melt flow ratio, I.sub.10/ I.sub.2, of at least about 8, and at least about 0.5 percent by weight of the interpolymer product has a weight average molecular weight of at least about 1,000,000 grams/mole. The interpolymer products are a blend or composite of ethylene polymers or copolymers and comprise at least a first interpolymer of ethylene with at least one alpha-olefin monomer. Preferably, the interpolymer products have a melt index, I.sub.2, of from about 0.1 to about 4 grams/10 minutes. The interpolymer products can be made using discrete polymer blends, or preferably, in a multiple reactor sequence. Blown film made from the interpolymer products is especially useful in grocery sack applications.
    Type: Grant
    Filed: July 15, 1993
    Date of Patent: December 6, 1994
    Assignee: The Dow Chemical Company
    Inventors: Lonnie G. Hazlitt, Pak-Wing S. Chum, Seema V. Karande, John E. Lastovica, III, Ian M. Munro
  • Patent number: 5346732
    Abstract: Super high flow ethylene polymer compositions comprising at least one linear ethylene polymer are disclosed which have improved processability for use in making thermally formed articles (e.g., thin-walled lids, cups and containers). The compositions have a processing index from about 0.005 KPoise to about 1 KPoise and are particularly useful in thermal forming processes having shear rates of at least 2,000 sec.sup.-1 (e.g., injection molding processes). The compositions can be used to make thin-walled lids and cups and have good environmental stress crack resistance and Gullwing Tear properties.
    Type: Grant
    Filed: August 4, 1992
    Date of Patent: September 13, 1994
    Assignee: The Dow Chemical Company
    Inventors: Shih-Yaw Lai, Lonnie G. Hazlitt, Pak-Wing S. Chum
  • Patent number: 5288762
    Abstract: Disclosed is a cross-linked ethylenic polymer foam structure of an ethylenic polymer material of a cross-linked, substantially linear ethylenic polymer. The substantially linear ethylenic polymer having in an uncross-linked state has: a) a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63; b) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation: M.sub.w /M.sub.n .gtoreq.(I.sub.10 /I.sub.2)- 4.63; and c) a critical shear rate at onset of surface melt fracture of at least 50 percent greater than the critical shear rate at the onset of surface melt fracture of a linear ethylenic polymer having about the same I.sub.2 and M.sub.w /M.sub.n. Further disclosed is a process for making the above foam structure.
    Type: Grant
    Filed: April 28, 1993
    Date of Patent: February 22, 1994
    Assignee: The Dow Chemical Company
    Inventors: Chung P. Park, Pak-Wing S. Chum, George W. Knight
  • Patent number: 5272236
    Abstract: Substantially linear olefin polymers having a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63, a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation: M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and a critical shear stress at onset of gross melt fracture of greater than about 4.times.10.sup.6 dyne/cm.sup.2 and their method of manufacture are disclosed. The substantially linear olefin polymers preferably have at least about 0.01 long chain branches/1000 carbons and a molecular weight distribution from about 1.5 to about 2.5. The new polymers have improved processability over conventional olefin polymers and are useful in producing fabricated articles such as fibers, films, and molded parts.
    Type: Grant
    Filed: October 15, 1991
    Date of Patent: December 21, 1993
    Assignee: The Dow Chemical Company
    Inventors: Shih-Yaw Lai, John R. Wilson, George W. Knight, James C. Stevens, Pak-Wing S. Chum
  • Patent number: 5250612
    Abstract: Film having good blocking properties and low coefficient of friction is prepared without the presence of antiblock additives from certain thermoplastic ethylene interpolymer products. The thermoplastic ethylene interpolymer products have a density of about 0.935 g/ml or less, a melt flow ratio. I.sub.10 I.sub.2, of at least about 8, and at least about 0.5 percent by weight of the interpolymer product has a weight average molecular weight of at least about 1,000,000 grams/mole. The interpolymer products are a blend or composite of ethylene polymers or copolymers and comprise at least a first interpolymer of ethylene with at least one alpha-olefin monomer. Preferably, the interpolymer products have a melt index, I.sub.2, of from about 0.1 to about 4 grams/10 minutes. The interpolymer products can be made using discrete polymer blends, or preferably, in a multiple reactor sequence. Blown film made from the interpolymer products is especially useful in grocery sack applications.
    Type: Grant
    Filed: October 7, 1991
    Date of Patent: October 5, 1993
    Assignee: The Dow Chemical Company
    Inventors: Lonnie G. Hazlitt, Pak-Wing S. Chum, Seema V. Karande, John E. Lastovica, III, Ian M. Munro
  • Patent number: 5231151
    Abstract: A transition metal containing catalyst useful for the polymerization of .alpha.-olefins is prepared by (A) forming in an inert atmosphere which excludes oxygen and moisture a slurry of (1) a porous inorganic oxide support material selected from the group consisting of silica, alumina, or a combination of silica and alumina, said support material containing not greater than about 5 millimoles of hydroxyl groups per gram of support material and a particle size not greater than about 10 microns and a surface area of from about 50 to about 800 m.sup.2 /g in an inert organic liquid medium; (B) mixing said slurry with (2) an alkoxide and stirring the resultant mixture at a temperature of from about -20.degree. C. to about 120.degree. C. for a time sufficient to saturate the surface of the support material; (C) mixing the product form (B) with (3) a titanium compound or a combination of a titanium compound and (4) a vanadium compound and stirring the resultant mixture at a temperature of from about -20.degree. C.
    Type: Grant
    Filed: March 20, 1992
    Date of Patent: July 27, 1993
    Assignee: The Dow Chemical Company
    Inventors: Lee Spencer, Brian W. S. Kolthammer, Miriam P. Ripplinger, Jeffrey J. Wooster, Pak-Wing S. Chum, Jacquelyn A. deGroot
  • Patent number: 5091250
    Abstract: A light-stable, optically clear laminate construction and method of making it which utilizes inexpensive styrenic polymers is provided. The laminate formed exhibits strong interfacial adhesion without the need for additional glue or adhesive layers through the use of pendant functionalized hydroxyl groups incorporated into the styrenic polymer by copolymerization. These pendant hydroxyl groups react with active pendant ester groups on the other polymer layer in the laminate to form strong covalent interfacial bonds by heating the layers, preferably either in a compression molding step or during coextrusion of the layers.
    Type: Grant
    Filed: February 6, 1990
    Date of Patent: February 25, 1992
    Assignee: The Dow Chemical Company
    Inventors: Pak-Wing S. Chum, Mark A. Barger
  • Patent number: 5089321
    Abstract: Multilayer thermoplastic film structures comprising at least one heat-sealable outer layer (A) and at least one core layer (B) are disclosed. Layer (A) has improved heat sealability after irradiation (e.g. electron beam). Layer (B) has improved shrinkage after irradiation. Layer (A) is a linear polyethylene having a melt index from about 2 to about 20 g/10 minutes, a density from about 0.88 to about 0.92 g/cc, a molecular weight distribution (I.sub.10 /I.sub.2) from about 5 to about 8, a fraction of the polyethylene having a degree of branching less than or equal to 2 methyls/1000 carbons of not more than 15% by weight and a fraction of the polyethylene having a degree of branching greater than or equal to 25 methyls/1000 carbons of not more than 25% by weight of the polymer. Layer (B) is a linear polyethylene having a melt index from about 0.05 to about 5 g/10 minutes, a density from about 0.88 to about 0.94 g/cc and a molecular weight distribution (I.sub.10 /I.sub.2) from about 8 to about 30.
    Type: Grant
    Filed: January 10, 1991
    Date of Patent: February 18, 1992
    Assignee: The Dow Chemical Company
    Inventors: Pak-Wing S. Chum, Kaelyn C. Koch