Patents by Inventor Chih M. Hwa

Chih M. Hwa 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: 5587109
    Abstract: A method of treating an aqueous system is described which comprises incorporating in the system a hydroxylamine derivative of the general formula: ##STR1## wherein each of R.sub.1, R.sub.2 and R.sub.3 which may be the same or different represents hydrogen, alkyl of 1 to 8 carbon atoms or aryl or a water soluble salt thereof or a precursor thereof, and a tannin in a weight ratio of at least 2:1. This is particularly useful for boiler water systems.
    Type: Grant
    Filed: April 19, 1995
    Date of Patent: December 24, 1996
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Brian Greaves, Stephen C. Poole, Chih M. Hwa, Joseph C. Fan
  • Patent number: 5244600
    Abstract: A method for inhibiting or preventing corrosion of metals in contact with an aqueous system containing dissolved oxygen comprising adding to the system an oxygen scavenger having the formula ##STR1## wherein n is 5 or 6, lactone derivatives thereof, or its water soluble salts, in an amount effective to substantially remove the dissolved oxygen.
    Type: Grant
    Filed: March 2, 1992
    Date of Patent: September 14, 1993
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa, Murrell L. Salutsky
  • Patent number: 5183574
    Abstract: A method of comprising iron in an aqueous system comprising adding to the system a copolymer of styrene sulfonic acid and methacrylic acid or its water soluble salt in an amount effective to disperse the iron contained therein.
    Type: Grant
    Filed: November 18, 1991
    Date of Patent: February 2, 1993
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Wun T. Tai, Lai-Duien G. Fan, Robert P. Kreh, Brian Greaves
  • Patent number: 5176849
    Abstract: A composition and method of inhibiting corrosion in boiler-steam condensate systems comprising adding to the system N,N-dihydrocarbylhydroxylamine and N-hydrocarbylhydroxylamine in amounts effective to inhibit corrosion.
    Type: Grant
    Filed: April 15, 1992
    Date of Patent: January 5, 1993
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, Dionisio G. Cuisia, Ronald L. Oleka
  • Patent number: 5167866
    Abstract: This invention relates to controlling corrosion in aqueous systems and more particularly to using certain calcium insensitive phosphonomethyl amine oxide compounds. The compounds of this invention are water soluble phosphonomethyl amine oxides having at least one oxidized tertiary amine group of the formula: ##STR1## and water soluble salts thereof and having a cloud point of at least about 25 ppm.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: December 1, 1992
    Assignee: W. R. Grace & Co. Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Janet Neton, Patricia M. Scanlon, Roger R. Gaudette
  • Patent number: 5096595
    Abstract: This invention relates to controlling scale formation in aqueous systems and more particularly to using certain calcium insensitive phosphonomethyl amine oxide compounds having at least one oxidized tertiary amine group of the formula: ##STR1## and water soluble salts thereof.
    Type: Grant
    Filed: February 11, 1991
    Date of Patent: March 17, 1992
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Janet Neton, Patricia M. Scanlon, Roger R. Gaudette
  • Patent number: 5069798
    Abstract: This invention relates to certain calcium insensitive phosphonomethyl amine compounds and their use as scale control agents for treating aqueous systems. The compounds of this invention are water-soluble phosphonomethyl amine compounds having the formula: ##STR1## and water soluble salts thereof selected from the group consisting of N-phosphonomethyl iminodiacetic acid, N,N-bis-phosphonomethyl- 2-(hydroxyethoxy)ethylamine, 4-(phosphonomethyl)-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane, N,N-bis-phosphonomethyl taurine and N,N-bis-phosphonomethyl ethylamine; and having a cloud point of at least about 25 ppm as determined by the CA500 cloud point test or a water soluble salt of said phosphonomethyl amine.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: December 3, 1991
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Janet Neton, Patricia M. Scanlon, Roger R. Gaudette
  • Patent number: 5051532
    Abstract: This invention relates to novel organic phosphonate compounds which can be used as water treatment agents. More specifically, this invention relates to the compound N,N-bis-phosphonomethyl taurine N-oxide which may be represented by the formula: ##STR1## and its water soluble salts, which can be employed for the control of scale and/or corrosion.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: September 24, 1991
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Janet Neton, Patricia M. Scanlon, Roger R. Gaudette
  • Patent number: 5019343
    Abstract: This invention relates to a method for preventing corrosion and inhibiting the formation of scale deposition in aqueous systems. More specifically, it relates to using certain calcium insensitive phosphonomethyl amine compounds having the formula: ##STR1## wherein either R.sub.1 is selected from hydrogen, hydrocarbyl, hydroxy-substituted hydrocarbyl, alkoxy-substituted hydrocarbyl; and R.sub.2 is selected from hydrocarbyl, hydroxy-substituted hydrocarbyl, alkoxy-substituted hydrocarbyl, carboxyl-substituted hydrocarbyl, --CH.sub.2 PO.sub.3 H.sub.2, and --C.sub.2 H.sub.4 N(CH.sub.2 PO.sub.3 H.sub.2).sub.2 ; or R.sub.1 and R.sub.2 together form an alicyclic ring having 3 to 5 carbon atoms, optionally along with oxygen atoms, phosphorus atoms or both oxygen and phosphorus atoms in the ring, and water soluble salts thereof.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: May 28, 1991
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Janet Neton, Patricia M. Scanlon, Roger R. Gaudette
  • Patent number: 4980128
    Abstract: Corrosion of metals in contact with system water in an aqueous system is inhibited by adding to the system water an effective amount of an oxygen scavenger selected from the group of nitrones having the formula: ##STR1## wherein R.sub.1 and R.sub.2 may be the same or different and are each a member selected from the group consisting of hydrogen and hydrocarbon radicals having between 1 and 10 carbon atoms, and R.sub.3 is a hydrocarbon radical having between 1 and 10 carbon atoms; or water soluble salts thereof.
    Type: Grant
    Filed: March 16, 1987
    Date of Patent: December 25, 1990
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa, Murrell L. Salutsky
  • Patent number: 4977292
    Abstract: This invention relates to novel organic phosphonate compounds and more particularly to the compound 4-phosphonomethyl-2-hydroxy-2-oxo-1,4,2-oxazaphosphonrinane N-oxide and water soluble salts thereof. These compounds are useful as water treatment agents which can be employed for the control of scale and/or corrosion control.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: December 11, 1990
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Mita Adhya
  • Patent number: 4973744
    Abstract: This invention relates to novel organic phosphonate compounds, and more particularly to ethoxylated N,N-bis-phosphonomethyl 2-(hydroxy) ethylamine N-oxides and their water soluble salts. These novel organic phosphonates are useful as water treatment agents which can be employed for the control of scale and/or corrosion.
    Type: Grant
    Filed: December 15, 1989
    Date of Patent: November 27, 1990
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Chih M. Hwa, John A. Kelly, Mita Adhya
  • Patent number: 4847001
    Abstract: A method and composition for inhibiting the corrosion of metal surfaces in contact with the system water of aqueous systems are disclosed, which use a combination of at least one compound selected from 2,5 dihydroxybenzene sulfonic acid and its water soluble salts and at least one amine selected from neutralizing amines and hydroxylamines.
    Type: Grant
    Filed: July 1, 1987
    Date of Patent: July 11, 1989
    Assignee: W. R. Grace & Co.-Conn.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa, Murrell L. Salutsky
  • Patent number: 4680125
    Abstract: A composition for inhibiting deposition of scale in aqueous systems is disclosed which comprises carboxymethylcellulose and gluconic acid or glucoheptonic acid or both, or their water soluble salts. The composition is incorporated in the aqueous system in concentrations sufficient to substantially completely prevent scale deposition.
    Type: Grant
    Filed: June 6, 1986
    Date of Patent: July 14, 1987
    Assignee: W. R. Grace & Co.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa
  • Patent number: 4649025
    Abstract: Composition for inhibition of ferrous metal corrosion consisting essentially of (a) HEDPA compound and (b) HPAA compound. Optionally the composition may also include (c) an azole.
    Type: Grant
    Filed: September 16, 1985
    Date of Patent: March 10, 1987
    Assignee: W. R. Grace & Co.
    Inventors: Chih M. Hwa, Wayne A. Mitchell
  • Patent number: 4631131
    Abstract: The accumulation of scale in an aqueous system is inhibited by the addition of a copolymer of maleic acid or anhydride or fumaric acid and allyl sulfonic acid and a water soluble organic phosphonic acid such as aminotri(methylene phosphonic acid), ethylenediaminetetra(methylene phosphonic acid), hydroxyethylidene diphosphonic acid and 2-phosphonobutane tricarboxylic acid-1,2,4 or water soluble salts thereof. Scale can actually be removed by the addition of these materials to pressurized boiler water systems. Allyl or vinyl copolymers, a phosphonate, and optionally a water soluble, hardness precipitating agent such as a carbonate or a phosphate may be used when treating pressurized boilers to provide an in-service cleaning effect.
    Type: Grant
    Filed: September 10, 1985
    Date of Patent: December 23, 1986
    Assignee: R. W. Grace & Co.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa
  • Patent number: 4609483
    Abstract: A composition for inhibiting deposition of scale in aqueous systems is disclosed which comprises carboxymethylcellulose and gluconic acid or glucoheptonic acid or both, or their water soluble salts. The composition is incorporated in the aqueous system in concentrations sufficient to substantially completely prevent scale deposition.
    Type: Grant
    Filed: March 7, 1985
    Date of Patent: September 2, 1986
    Assignee: W. R. Grace & Co.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa
  • Patent number: 4600524
    Abstract: The accumulation of scale in an aqueous system is inhibited by the addition of a copolymer of maleic acid or anhydride or fumaric acid and allyl sulfonic acid and a water soluble organic phosphonic acid such as aminotri(methylene phosphonic acid), ethylenediaminetetra(methylene phosphonic acid), hydroxyethylidene diphosphonic acid and 2-phosphonobutane tricarboxylic acid-1,2,4 or water soluble salts thereof. Scale can actually be removed by the addition of these materials to pressurized boiler water systems. Allyl or vinyl copolymers, a phosphonate, and optionally a water soluble, hardness precipitating agent such as a carbonate or a phosphate may be used when treating pressurized boilers to provide an in-service cleaning effect.
    Type: Grant
    Filed: December 8, 1983
    Date of Patent: July 15, 1986
    Assignee: W. R. Grace & Co.
    Inventors: Dionisio G. Cuisia, Chih M. Hwa
  • Patent number: 4581145
    Abstract: The accumulation of scale in an aqueous system is inhibited by the addition of a composition comprising a copolymer of maleic acid or anhydride and vinyl sulfonic acid and an organic phosphonate such as aminotri(methylene phosphonic acid), hydroxyethylidene diphosphonic acid, or a water soluble salt thereof.
    Type: Grant
    Filed: March 11, 1985
    Date of Patent: April 8, 1986
    Assignee: Dearborn Chemical Company
    Inventors: Dionisio G. Cuisia, Chih M. Hwa, Anne H. Kemp
  • Patent number: 4350606
    Abstract: Corrosion in steam condensate lines is inhibited by maintaining a mix of a hydroxylamine compound and a neutralizing amine in the water.
    Type: Grant
    Filed: October 3, 1980
    Date of Patent: September 21, 1982
    Assignee: Dearborn Chemical Company
    Inventors: Dionisio G. Cuisia, Chih M. Hwa