Alkali Or Alkaline Earth Metal Containing Patents (Class 106/449)
  • Patent number: 6197104
    Abstract: The present invention discloses high solids slurries of anatase titanium dioxide pigment comprising greater than about 75% by weight of anatase TiO2 pigment dispersed in water. A process for producing the slurries of the present invention is disclosed which comprises the steps of a) dry milling the anatase titanium dioxide pigment, preferably by pressure rolling, and b) mixing the dry milled pigment with water in the presence of an acrylic acid dispersant.
    Type: Grant
    Filed: May 4, 1998
    Date of Patent: March 6, 2001
    Assignee: Millennium Inorganic Chemicals, Inc.
    Inventors: Robert J. Kostelnik, Fu-chu Wen
  • Patent number: 6143064
    Abstract: This invention relates to a pigment particle product and a method for its preparation. According to the invention pigment particles, such as kaolin, natural calcium carbonate or titanium dioxide, and precipitated calcium carbonate are mixed together in an aqueous phase at pH 6-11, which causes the pigment particles to become coated with particles of precipitated calcium carbonate. The brightness of the product is excellent, and it is quite inexpensive to produce.
    Type: Grant
    Filed: October 27, 1998
    Date of Patent: November 7, 2000
    Assignee: FP-Pigments Oy
    Inventor: Pentti Virtanen
  • Patent number: 6103360
    Abstract: A ceiling board coating composition includes water, a binder and a filler, said filler having large particles with an average particle size of a minimum of about 50 microns, medium particles with an average particle size in the range of from about 1.2 to about 30 microns, and small particles which have an average particle size in the range of from about 0.1 to about 1.0 microns.
    Type: Grant
    Filed: January 9, 1998
    Date of Patent: August 15, 2000
    Assignee: Armstrong World Industries, Inc.
    Inventors: Kenneth G. Caldwell, Raymond H. Fernando
  • Patent number: 6080232
    Abstract: The invention relates to spherical colored pigments having an average particle diameter of less than 10 .mu.m on the basis of an oxide, a mixed oxide or a silicate. The pigments are obtainable by means of spray-pyrolysis technology: a solution containing oxide-forming or silicate-forming metal compounds is converted into an aerosol and the latter is fed, preferably after predrying, to a pyrolysis reactor; the pigment is separated from the pyrolysis gas. The colored pigments according to the invention are suitable for the production of ceramic decorations and for the coloring of plastics, synthetic foils, fibers and also lacquers. By reason of the spherical shape, unusual technical application properties are achieved.
    Type: Grant
    Filed: November 14, 1997
    Date of Patent: June 27, 2000
    Assignee: Degussa Aktiengesellschaft
    Inventors: Jorg Sperlich, Ralph Brandes, Hauke Jacobsen, Stipan Katusic, Andreas Schulz
  • Patent number: 6036763
    Abstract: In one embodiment, the present invention relates to a KOH neutralized metatitanic acid mixture containing from about 30% to about 99% by weight metatitanic acid, from about 1% to about 20% by weight of a titanyl compound, and optionally from about 0% to about 55% by weight titanium dioxide, wherein the KOH neutralized metatitanic acid mixture has a pH from about 4 to about 6.5. In another embodiment, the present invention relates to a pigment composition made by combining a KOH neutralized metatitanic acid mixture and at least one guest element precursor, wherein the KOH neutralized metatitanic acid mixture contains metatitanic acid, a titanyl compound, and optionally titanium dioxide, the KOH neutralized metatitanic acid mixture having a pH from about 4 to about 6.5.
    Type: Grant
    Filed: October 16, 1998
    Date of Patent: March 14, 2000
    Assignee: Engelhard Corporation
    Inventors: Thomas V. Edwards, William L. Howell, Jr., Frank A. Mazzella
  • Patent number: 5968248
    Abstract: A heat-resistant inorganic pigment of the present invention comprises a composite metal oxide containing Ti and two divalent metals selected from the group consisting of Mg, Fe, Ni and Co, the content of said two divalent metals in said composite metal oxide being 0.95 to 1.05, in an atomic ratio, based on Ti, and the composition ratio of said two divalent metals being 95/5 to 5/95 in an atomic ratio. The pigment of the present invention is useful as a pigment for a heat-resistant coating material and is a novel heat-resistant inorganic pigment which does not pollute the environment.
    Type: Grant
    Filed: February 13, 1997
    Date of Patent: October 19, 1999
    Assignees: General of Agency of Industrial Science, Toda Kogyo Corporation
    Inventors: Yasuo Shibasaki, Kiichi Oda, Saburo Sano, Shigehisa Yamamoto, Nanao Horiishi
  • Patent number: 5958125
    Abstract: Goniochromatic luster pigments based on multiply coated, high refractive, nonmetallic, platelet-shaped substrates which are at least partially transparent to visible light, comprising at least one layer packet ofA) a colorless coating having a refractive index n.ltoreq.1.8 andB) a reflecting, selectively or nonselectively absorbing coating which is at least partially transparent to visible light,and also, if desired, additionallyC) an outer protective layer,and their use for coloring paints, inks, including printing inks, plastics, glasses, ceramic products and decorative cosmetic preparations.
    Type: Grant
    Filed: July 5, 1996
    Date of Patent: September 28, 1999
    Inventors: Raimund Schmid, Norbert Mronga
  • Patent number: 5951750
    Abstract: Antioxidant-containing polyolefin compositions are provided including titanium dioxide-coated mica particles having an overcoating calcined thereon to prevent yellowing of the compositions. Reduced photo-darkening and improved densification of the pigment can also be achieved.
    Type: Grant
    Filed: June 19, 1997
    Date of Patent: September 14, 1999
    Assignee: Engelhard Corporation
    Inventors: Curtis J. Zimmermann, J. Mike Hanckel
  • Patent number: 5942281
    Abstract: Process for the surface treatment of a titanium dioxide pigment, characterized in that it comprises the following steps:an aqueous suspension of titanium dioxide pigments is formed,in a first step, a layer of alumina phosphate is precipitated on the surface of the pigment,in a second step, a layer of alumina is precipitated over the first layer of alumina phosphate,the pigment is recovered from the suspension;and titanium dioxide pigment, characterized in that it comprises a titanium dioxide core coated successively with a layer of alumina phosphate, then with a layer of alumina and then with a layer of magnesium oxide.
    Type: Grant
    Filed: April 26, 1997
    Date of Patent: August 24, 1999
    Inventors: Anny Guez, Remy Lorang
  • Patent number: 5922121
    Abstract: A surface derivatizing agent is allowed to contact an aqueous slurry of transition metal-containing pigment particles to increase the hydrophobicity of the surface of such particles. The modified pigment particles disperse easily in a wide variety of organic solvents, and provide stable, dispersions having a small mean pigment particle size and narrow particle size distribution.
    Type: Grant
    Filed: May 24, 1996
    Date of Patent: July 13, 1999
    Assignee: Videojet Systems International, Inc.
    Inventor: Wing Sum Vincent Kwan
  • Patent number: 5910213
    Abstract: A pigmentary material comprises particulate titanium dioxide the particles of which have been treated with a polymeric hindered amine stabiliser. The stabiliser is a polymer having a main chain substantially free of acidic groups and having hindered amine stabilising groups. The stabilising groups comprise at least 35 per cent by weight of the polymer. Preferably, the titanium dioxide particles are also treated with an organic compound such as a polyhydric alcohol, an alkanolamine, a polysiloxane or a fatty acid.
    Type: Grant
    Filed: July 31, 1997
    Date of Patent: June 8, 1999
    Assignee: Tioxide Group Services Limited
    Inventors: Steven Hugh Ashdown, Robert McIntyre, Neil Martin Richmond
  • Patent number: 5908498
    Abstract: A process for preparing a low-dusting, free-flowing pigment which has not been subjected to any micronizing treatment comprising the steps of providing an inorganic pigment material; providing a source of water; forming a fine, well dispersed slurry of the pigment and water; milling the slurry; depositing a treating agent having the formula ROOCCHSO.sub.3 MCH.sub.2 COOR' wherein R and R' are monovalent alkyl radicals having from about 2 to about 20 carbon atoms, and M is a metallic monovalent cation on the slurried milled pigment; and drying the pigment material having a treating agent deposited thereon. The invention also provides the free-flowing pigments produced by this process.
    Type: Grant
    Filed: March 31, 1998
    Date of Patent: June 1, 1999
    Assignee: Kerr-McGee Chemical LLC
    Inventors: James W. Kauffman, Phillip M. Story, John E. Halko
  • Patent number: 5886069
    Abstract: The present invention relates to TiO.sub.2 pigments having TiO.sub.2 particles with substantially discrete inorganic particles dispersed on the surfaces of the TiO.sub.2 particles. Suitable inorganic particles include silica, calcium carbonate, and mixtures thereof. The substantially discrete inorganic particles have an average diameter size within the range of about 5 to about 50 nm and are dispersed on the surfaces of the TiO.sub.2 particles in an amount of less than 20 wt. % based on total pigment weight. This invention also includes coating compositions containing these pigments and processes for making these pigments.
    Type: Grant
    Filed: May 8, 1997
    Date of Patent: March 23, 1999
    Assignee: E. I. du Pont de Nemours and Company
    Inventor: John Davis Bolt
  • Patent number: 5855661
    Abstract: A method for preparing modified pigment particles including contacting an aqueous slurry of metallo, mono and bi-dentate ligand pigment particles with a surface derivatizing agent having one or more phenolic moieties, a 1, 3-diketo moiety or a combination thereof.
    Type: Grant
    Filed: January 18, 1996
    Date of Patent: January 5, 1999
    Assignee: Videojet Systems International, Inc.
    Inventor: Wing Sum Vincent Kwan
  • Patent number: 5833892
    Abstract: In a method of producing TiO.sub.2 pigment particles a TiO.sub.a X.sub.b (OH).sub.c -based precursor is suspended in a liquid with or without fuel additives. The suspension is then sprayed to form droplets. The droplets are transported into a flow reactor with a carrier gas. The droplets are decomposed in the flow reactor at high temperatures to form TiO.sub.2 pigment particles which are collected downstream of the flow reactor. In a preferred embodiment, a colloidal suspension of an insoluble TiO(SO.sub.4).sub.b (OH).sub.c precipitate with suitable fuel additives was spray-calcined at 900.degree. to 1200.degree. C. to produce pigment-quality TiO.sub.2. The primary particle size of the TiO.sub.2 pigment particles is between 150-250 nm and the particles are minimally aggregated.
    Type: Grant
    Filed: July 12, 1996
    Date of Patent: November 10, 1998
    Assignee: Kemira Pigments, Inc.
    Inventors: Abhijit S. Gurav, Toivo T. Kodas, Bruce M. Anderson
  • Patent number: 5770310
    Abstract: Composite fine particles of metal oxides containing titanium dioxide which produce a remarkable ultraviolet screening effect over the entire region of spectrum. Each particle is composed of a core and a surface layer, said core being composed of a nucleus formed from (a) titanium dioxide or (b) iron oxide or (c) a mixture of iron oxide and titanium dioxide and an outer layer of titanium dioxide, said surface layer being formed from metal oxides of magnesium and calcium.
    Type: Grant
    Filed: April 1, 1997
    Date of Patent: June 23, 1998
    Assignee: Merck Patent Gesellschaft Mit Beschrankter Haftung
    Inventors: Tamio Noguchi, Yukitaka Watanabe
  • Patent number: 5766336
    Abstract: Colored pigments are provided from the green-yellow to red spectrum based on oxide-nitrides with two or three different cations Q, R and S in the crystal lattice, wherein the nitrogen to oxygen atomic ratio is determinative for the color. These pigments crystallise in the pyrochlore, spinel or elpasolite structure. Pigments in the perovskite are as provided with increased color brilliance. The color of the pigments can be adjusted in a wide range of the color spectrum during their preparation within a substance class with the cations Q, R and S and while retaining the crystal structure, by increasing or lowering the atomic ratio N to O in the oxide-nitride and bringing about the required charge balancing by replacing an equivalent quantity of the cation Q with the valency q by a cation R with the valency q+1.
    Type: Grant
    Filed: August 21, 1995
    Date of Patent: June 16, 1998
    Assignee: Cerdec Aktiengesellschaft Keramische Farben
    Inventors: Martin Jansen, Hans-Peter Letschert
  • Patent number: 5746819
    Abstract: The present invention discloses high solids slurries of sulfate process, anatase titanium dioxide pigment. The improvements of these slurries over those of the prior art are improved slurry stability, tolerance to calcium and magnesium ions, foaming tendencies and reduced tendency to flocculate. The slurries of the present invention are comprised of at least 65% by weight of anatase TiO.sub.
    Type: Grant
    Filed: November 14, 1995
    Date of Patent: May 5, 1998
    Assignee: SCM Chemicals, Inc.
    Inventors: Robert J. Kostelnik, Fu-Chu Wen
  • Patent number: 5733365
    Abstract: A process for preparing a low-dusting, free-flowing pigment which has not been subjected to any micronizing treatment comprising the steps of providing an inorganic pigment material; providing a source of water; forming a fine, well dispersed slurry of the pigment and water; milling the slurry; depositing a treating agent having the formula ROOCCHSO.sub.3 MCH.sub.2 COOR' wherein R and R' are monovalent alkyl radicals having from about 2 to about 20 carbon atoms, and M is a metallic monovalent cation on the slurried milled pigment; and drying the pigment material having a treating agent deposited thereon. The invention also provides the free-flowing pigments produced by this process.
    Type: Grant
    Filed: February 18, 1997
    Date of Patent: March 31, 1998
    Assignee: Kerr-McGee Corporation
    Inventors: John E. Halko, Phillip M. Story, James W. Kauffman, Kelly A. Green
  • Patent number: 5665466
    Abstract: Process for the surface treatment of a titanium dioxide pigment, characterized in that it comprises the following steps:an aqueous suspension of titanium dioxide pigments is formed,in a first step, a layer of alumina phosphate is precipitated on the surface of the pigment,in a second step, a layer of alumina is precipitated over the first layer of alumina phosphate,the pigment is recovered from the suspension;and titanium dioxide pigment, characterized in that it comprises a titanium dioxide core coated successively with a layer of alumina phosphate, then with a layer of alumina and then with a layer of magnesium oxide.
    Type: Grant
    Filed: November 8, 1995
    Date of Patent: September 9, 1997
    Assignee: Rhone-Poulenc Chimie
    Inventors: Anny Guez, Remy Lorang
  • Patent number: 5650002
    Abstract: A TiO.sub.2 pigment particle having a surface coating of inorganic particles or mineral particles exhibiting improved light scattering efficiency of TiO.sub.2 at a moderate to high pigment volume concentration (PVC) and a low oil absorption when incorporated in coatings applications is disclosed, and methods of accomplishing the same.
    Type: Grant
    Filed: November 13, 1995
    Date of Patent: July 22, 1997
    Assignee: E. I. Du Pont de Nemours and Company
    Inventor: John Davis Bolt
  • Patent number: 5565025
    Abstract: The invention relates to surface-modified pigments based on TiO.sub.2 pigments or TiO.sub.2 -coated platelet-shaped substrates and overcoated with a layer consisting of borates of alkaline earth metals and/or double borates of alkali and/or alkaline earth metals and to the use thereof as yellowness inhibitors in plastics and plastics systems.
    Type: Grant
    Filed: September 1, 1994
    Date of Patent: October 15, 1996
    Assignee: Merck Patent Gesellschaft mit Beschrankter Haftung
    Inventor: Matthias Schraml-Marth
  • Patent number: 5433779
    Abstract: A pearlescent pigment comprising micaceous particles having an adherent layer of rutile titanium dioxide thereon is prepared by effecting the deposition of hydrous titanium dioxide on the micaceous particles in the presence of iron and calcium, magnesium and/or zinc ions without the use of tin.
    Type: Grant
    Filed: November 7, 1994
    Date of Patent: July 18, 1995
    Assignee: The Mearl Corporation
    Inventor: Carmine V. DeLuca, Jr.
  • Patent number: 5338354
    Abstract: A new process for preparing a composite pigment from titanium dioxide and calcium sulphate is provided in which the calcium sulphate is milled to a particle size less than 10 microns, mixed with titanium dioxide and the mixed particulates are coated with an oxide or hydrous oxide of a metal or silicon. The process can particularly be employed in conjunction with a sulphate-process titanium dioxide plant in which by-product sulphuric acid is converted to gypsum. The composite pigment shows improved optical properties in comparison to a mixture of titanium dioxide and gypsum.
    Type: Grant
    Filed: June 23, 1993
    Date of Patent: August 16, 1994
    Assignee: Tioxide Group Services Limited
    Inventors: Iain A. Melville, Robert P. Rauch, deceased
  • Patent number: 5336312
    Abstract: This invention relates to colorants represented by the formulaBi.sub.2 A.sub.x-1 D.sub.x O.sub.ywherein: A is selected from the group consisting of Bi, Ba, Sr, Ca, Y, La, or a mixture of two or more thereof; D is selected from the group consisting of V, Mo, Mn, Ti, Ta, Nb, W, Sb, Fe, Cr, Sn, Ce, or a mixture of two or more thereof; x is a number that is at least 1; and y is the number of oxygens needed to fulfill the valence requirements of Bi, A and D; with the proviso that when A is Bi, D is other than a mixture consisting of V and Mo. These colorants are useful in providing colored compositions including: organic compositions such as plastics, rubbers, and the like; inorganic compositions such as ceramics, porcelain enamels, and the like; and coating compositions such as paints, printing inks, and the like; etc. The invention also provides for processes for making such colorants and for making such colored compositions. The invention also provides for such colorants in the form of particulate solids (e.g.
    Type: Grant
    Filed: May 10, 1993
    Date of Patent: August 9, 1994
    Assignee: Ferro Corporation
    Inventors: Christine J. Byrne, Robert P. Blonski, John J. Welch
  • Patent number: 5336311
    Abstract: This invention relates to structural aggregate pigment products that are cationic, and have improved wet-end retention. A method for converting anionic pigments to cationic pigments is also provided. More particularly, a structural aggregate pigment comprising a clay and/or titanium dioxide or other particulate components, and a functional microgel made from silicon and aluminum or zinc gel formers and a gelling agent such as calcium chloride, can be cationized by adding an effective amount of modified or unmodified epichlorhydrin dimethylamine condensate to a slurry of the structured pigment. The resulting cationic pigments have superior papermaking characteristics and a much improved retention.
    Type: Grant
    Filed: July 7, 1992
    Date of Patent: August 9, 1994
    Assignee: Nord Kaolin Company
    Inventors: Jerry L. Curtis, Kenneth A. Johnson, Lester W. House
  • Patent number: 5332433
    Abstract: A titanium dioxide production method, a novel titanium dioxide product produced by the inventive titanium dioxide production method, a method for producing a plastic product using the novel titanium dioxide product, and a novel plastic product formed by the inventive plastic product production method. The inventive titanium dioxide production method comprises the steps of: (a) forming a mixture comprising a titanium dioxide material in a liquid medium; (b) wet milling the titanium dioxide material in the liquid medium; (c) after step (b), reducing the pH of the mixture to a value not exceeding 4.0; (d) after step (c), adding an effective amount of a base to the mixture to cause the titanium dioxide material to flocculate; (e) removing the flocculated titanium dioxide material from the mixture; and (f) washing the titanium dioxide material. The titanium dioxide material used in step (a) is an agglomerated titanium dioxide material which has been produced by a reaction process.
    Type: Grant
    Filed: November 24, 1993
    Date of Patent: July 26, 1994
    Assignee: Kerr-McGee Chemical Corporation
    Inventors: Phillip Story, Kelly A. Green, John E. Halko
  • Patent number: 5221341
    Abstract: The invention relates to surface-modified platelet-like pigments based on platelet-like substrates which are coated with a titanium dioxide layer and a thin alkaline earth metal titanate film on top of it, in which the pigment, in order to increase the photostability and to decrease the surface reactivity towards organic compounds, is ignited at temperatures of at least 800.degree. C.
    Type: Grant
    Filed: June 26, 1992
    Date of Patent: June 22, 1993
    Assignee: Merck Patent Gesellschaft mit beschrankter Haftung
    Inventors: Klaus-Dieter Franz, Johann Dietz, Manfred Kieser
  • Patent number: 5192365
    Abstract: Desirable buff rutile pigment compositions are described which comprise about 40 to about 55% by weight of titanium, from about 0.4 to about 5 parts by weight of cobalt, from about 7 to about 14% by weight of tungsten, from 0.01 to about 5 parts by weight of lithium and from about 0.1 to about 20 parts by weight of cerium.
    Type: Grant
    Filed: June 6, 1991
    Date of Patent: March 9, 1993
    Assignee: Engelhard Corporation
    Inventor: Zoltan M. Modly
  • Patent number: 5173386
    Abstract: The present invention provides novel titanium dioxide aggregates especially suitable for an electrophotographic photosensitive material. This titanium dioxide aggregates comprise sintered aggregates of fine primary particles and have a rutile type crystal structure and an oil absorption of 35-65. This titanium dioxide aggregates which are treated with a mineral acid is also provided. There is also provided an electrophotograpic photosensitive material which contains such titanium dioxide in a photosensitive layer.
    Type: Grant
    Filed: December 28, 1989
    Date of Patent: December 22, 1992
    Assignee: Ishihara Sangyo Kaisha, Ltd.
    Inventor: Sadao Murasawa
  • Patent number: 5120690
    Abstract: For a complete utilization of used DeNOx catalysts contaminated with fly ash, the catalyst is crushed to a particle size of usually less than 500 microns, admixed with the ash of a molten ash firing chamber of a coal power plant at weight ratio of usually at least 9 parts molten ash to 1 part catalyst where the catalyst is dissolved in the molten ash at a temperature generally above 1460.degree. C. The resulting molten ash chamber granulated material can be utilized in the usual way, for example in the construction industry, since no pollutants, especially no compounds of tungsten, molybdenum, vanadium and arsenic are eluted into the environment.
    Type: Grant
    Filed: April 25, 1991
    Date of Patent: June 9, 1992
    Assignee: Huels Aktiengesellschaft
    Inventors: Jurgen Jung, Helmut Kretschmer, Rolf Muller
  • Patent number: 5108739
    Abstract: A white colored deodorizer comprising titanium oxide and zinc oxide and a method for its preparation are disclosed.
    Type: Grant
    Filed: June 21, 1990
    Date of Patent: April 28, 1992
    Assignee: Titan Kogyo Kabushiki Kaisha
    Inventors: Tokumitsu Kurihara, Tatsuo Saito, Hidefumi Harada
  • Patent number: 5082648
    Abstract: A process for the preparation of high purity calcium titanate hydrates, particularly various forms of kassite, is disclosed. Calcium carbonate and titanium tetraisopropoxide are used as starting materials. The process utilizes a hydrothermal reaction step. Hydrates having both hexagonal plate form, wherein the particles have a hexagonally shaped flat plate-like morphology, and lath form, wherein the particles have a rod-like morphology are produceable according to the process. Particle morphology is determined by the choice of process parameters, especially the rate of heating during the hydrothermal reaction step. Kassite particles of the hexagonal plate form, which are useful as a high opacity paper coating pigment, are produced when the rate of heating is less than or equal to 1.5.degree. C./min. Faster rates of heating result in kassite particles of a lath form. These particles are useful as a reinforcing material in polymers and ceramics.
    Type: Grant
    Filed: October 11, 1990
    Date of Patent: January 21, 1992
    Assignee: Pfizer Inc.
    Inventors: John Damiano, Richard C. Griffin
  • Patent number: 4985079
    Abstract: Disclosed is a medium set cationic bituminous emulsion comprising, relative to the emulsion:a. about 40 to 75% by weight asphalt;b. 0.25 to 5% by weight of a cationic emulsifier;c. 0.1 to 0.5% by weight of a nonionic water-soluble thickening agent;d. 0 to 8% of a low-boiling hydrocarbon; ande. water as a continuous phase of said emulsion to make up 100% by weight;wherein said medium set emulsion when combined with open-graded aggregate produces a mix which has a thick coating of emulsion on said aggregate surface and said mix is workable and results in minimum runoff.
    Type: Grant
    Filed: April 5, 1989
    Date of Patent: January 15, 1991
    Assignee: Chevron Research Company
    Inventors: Peter E. Graf, Steven J. Agazzi, Eugene J. Vanderzanden
  • Patent number: 4885034
    Abstract: In a process for producing a composite TiO.sub.2 pigment which contains a white inert extender, the neutralization is simplified and the need for washing processes is eliminated in that a metatitanic acid suspension, which contains free and combined sulfuric acid and has been purified for the removal of chromophoric elements, is neutralized by an addition of calcium oxide and/or barium oxide in quantities which are stoichiometric with respect to total sulfate, the calcium sulfate and/or barium sulfate is precipitated in an intimate mixture with the metatitanic acid, and the coprecipitate is separated and dried. The precipitated calcium sulfate and/or barium sulfate is contained in the coprecipitate in an amount from 1 to 25% by weight.
    Type: Grant
    Filed: August 24, 1987
    Date of Patent: December 5, 1989
    Assignee: Metallgesellschaft Aktiengesellschaft
    Inventors: Wolfgang Kreth, Wolf-Dieter Griebler