Propionates, Butyrates Or Isobutyrates Patents (Class 536/68)
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Patent number: 6407224Abstract: A catalytic system for cellulose acylation includes an adduct of sulfuric acid with N,N-dimethylacetamide, free sulfuric acid or free N,N-dimethylacetamide with the following mole ratio of the components: adduct:1.0; free sulfuric acid, max:0.49; or free N,N-dimethylacetamide, max:0.4. A process for producing such a catalytic system is based upon reacting sulfuric acid with N,N-dimethylacetamide in an anhydrous medium at a temperature of 0° C.-25° C. with the following mole weight ratio of the components: sulfuric acid:1.0; N,N-dimethylacetamide, max:1.4. A process for cellulose acylation in the presence of this catalytic system incorporates cellulose treatment with acetic acid followed by treatment of the resultant activated cellulose with a lower fatty acid anhydride at a temperature of 10° C.-90° C. in the presence of this catalytic system taken in an amount of 1.5-30.0 wt.Type: GrantFiled: July 16, 1999Date of Patent: June 18, 2002Assignee: Nauchno-prozvodstvennaya firma “Efiry Tselljulosy”Inventors: Dmitry Petrovich Mironov, Anatoly Ivanovich Shamolin, Eduard Pavlovich Grishin, Valentin Ananievich Bondar
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Patent number: 6139785Abstract: The present invention provides a cellulose ester composition, containing 1 to 99% by weight of cellulose triacetate prepared by substituting hydroxyl groups of cellulose with acetyl and having a degree of substitution with acetyl, DSace, which satisfies the relationship: 2.7.ltoreq.DSace.ltoreq.3.0, and 99 to 1% by weight of a mixed fatty acid ester of cellulose prepared by substituting hydroxyl groups of cellulose with acetyl and acyl groups having three or more carbon atoms and having degrees of substitution with acetyl and acyl groups having three or more carbon atoms, DSace and DSacyl, respectively, which satisfy the relationships: (I) 2.20.ltoreq.DSace.ltoreq.2.95, (II) 0.05.ltoreq.DSacyl.ltoreq.0.80 and (III) 2.60.ltoreq.DSace+DSacyl.ltoreq.3.00.Type: GrantFiled: March 19, 1999Date of Patent: October 31, 2000Assignee: Daicel Chemical Industries, Ltd.Inventors: Yuichiro Shuto, Hiroki Taniguchi, Yukiko Nakanishi, Masahiko Murayama
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Patent number: 6063752Abstract: Acylated carbohydrates with at least one carboxyalkyl group etherified with the carbohydrate of the following general formulaKH(--O--CHR.sub.1 --(CH.sub.2).sub.p --(COOH or COO.sup.-)).sub.n (--O--CO--R.sub.2).sub.m,wherein KH (carbohydrate) is a monosaccharide, disaccharide, trisaccharide or polysaccharide, and whereinif KH is a monosaccharide, then n=1 to 4 and m=1 to 4 with n+m=2 to 5;if KH is a disaccharide, then n=1 to 7 and m=1 to 7 with n+m=2 to 8;if KH is a trisaccharide, then n=1 to 10 and m=1 to 10 with n+m=2 to 11; andif KH is a polysaccharide, then n=0.2 to 2.8 and m=0.2 to 2.8 with n+m=0.4 to 3 (with polysaccharide referred to the monosaccharide unit of the KH), and whereinR1 is=H or a moiety with 1-9 carbon atoms, in particular an alkyl or acyl moiety, andR2 is a moiety with 1-9 carbon atoms, in particular an alkyl or acyl moiety, and wherein p=0 to 9.Type: GrantFiled: June 18, 1997Date of Patent: May 16, 2000Assignee: Sudzucker Aktiengesellschaft Mannheim/OchsenfurtInventors: Sonja Ehrhardt, Alireza Haji Begli, Markwart Kunz
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Patent number: 5973139Abstract: A process for preparing a carboxylated cellulose ester from oxidized cellulose is described. The carboxylated cellulose esters have improved solvent solubility and coating resin compatibility when compared to cellulose esters made from regular grade cellulose. The process comprises activating the oxidized cellulose with water. The activated oxidized cellulose is then dehydrated by displacing the water with acetic acid and optionally displacing at least some of the acetic acid with butyric acid or propionic acid. After dehydration the activated cellulose is reacted with an esterifying reagent in the presence of a catalyst at about 0.degree. C. The temperature is gradually increased to a level sufficient to complete reaction and to obtain an intrinsic viscosity ranging from about 0.2 to about 1.6 dl/g. The reacted solution is then hydrolyzed to obtain a hydroxyl content ranging from about 0.05 to about 1.0.Type: GrantFiled: February 6, 1998Date of Patent: October 26, 1999Assignee: Eastman Chemical CompanyInventors: Benedict Moonsang Lee, Chung-Ming Kuo, Jessica Posey-Dowty, Larry Gerald Curtis
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Patent number: 5717087Abstract: The present invention relates to thermoplastic and biodegradable polysaccharide esters/polysaccharide ether esters, which are characterised in that they can be represented by the general structure ##STR1## wherein Polysaccharide-O represents the substituted OH groups of a polymeric saccharide unit and wherein A is a linear polyether chain of the following structureA=(E--O)nwherein E signifies a linear aliphatic or aromatic branched or unbranched chain having 2 to 11 C atoms, n is an integer equal to or greater than 0 and both B and D are a maleic acid addition product of the following structure ##STR2## wherein F is an aliphatic, saturated, monounsaturated or polyunsaturated carbon skeleton, which may optionally be provided with further substituents and wherein C can be a hydrogen atom, one or more substituents from the group dihydroxyethyl, hydroxypropyl, hydroxybutyl, methyl, ethyl, benzyl, dihydroxypropyl, carboxyalkyl, sulphoalkyl or cyanoethyl.Type: GrantFiled: August 2, 1996Date of Patent: February 10, 1998Assignee: Wolff Walsrode AGInventors: Jochen Kalbe, Reinhard Koch, Hanns Peter Muller, Jurgen Engelhardt, Wolfgang Koch, Volkhard Muller
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Patent number: 5674999Abstract: An improved process for surface treating water soluble cellulosic polymers with crosslinking agents to provide products which are more readily dispersible in cold water, and have longer viscosity delay times than can be achieved with polymers treated in low intensity mixers, such as ribbon blenders, comprising distributing the crosslinking agent using a continuous, high intensity mixer, followed by heating to facilitate surface crosslinking. This process also allows for a reduced level of crosslinking chemicals to be used.Type: GrantFiled: December 18, 1995Date of Patent: October 7, 1997Assignee: The Dow Chemical CompanyInventors: Michael R. Smith, Gary J. Schulz, Kenneth C. Reibert
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Patent number: 5597912Abstract: Process for reducing the degree of substitution of cellulose esters employing carboxylic acids as solvolysis promoters is disclosed. Exemplary cellulose esters are cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.Type: GrantFiled: March 4, 1994Date of Patent: January 28, 1997Assignee: Eastman Chemical CompanyInventors: Kevin J. Edgar, Charles M. Buchanan
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Patent number: 5488102Abstract: Compounds of formulae I and IaR--Y--CO--R.sub.3 --CO--O--A (I),R--Y--CO--R.sub.3 --CO--O--CH.sub.2 --A.sub.1 (Ia),whereinR is a radically polymerisable hydrocarbon group,R.sub.3 is a direct bond, linear or branched C.sub.1 -C.sub.22 alkylene, C.sub.3 -C.sub.8 cycloalkylene or C.sub.6 -C.sub.14 arylene,A is the radical, reduced by a hydroxy group in a 2- or 3position, of a cyclic-oligomeric carbohydrate or of a derivative of such a carbohydrate,A.sub.1 is the radical, reduced by a hydroxymethyl group, of a monomeric or linear oligomeric carbohydrate or of a derivative of such a carbohydrate, andY is --O--, --NH-- or --N(C.sub.1 -C.sub.6 alkyl)-.Homo- and co-polymers having those monomers have, depending upon their composition, hydrophilic, amphiphilic or hydrophobic properties and are able to form hydrogels. The polymers can be used, for example, as surfactants, thickeners, carriers for biologically active ingredients or in the manufacture of contact lenses.Type: GrantFiled: July 26, 1994Date of Patent: January 30, 1996Assignee: Ciba Geigy CorporationInventor: Dirk Vetter
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Patent number: 5192444Abstract: A separation agent essentially comprises an aliphatic or aromatic ester of a polysaccharide, except for cellulose acetate and an aromatic ester of cellulose. It is useful for separation of various chemical substances, especially optical resolution of optical isomers.Type: GrantFiled: December 18, 1991Date of Patent: March 9, 1993Assignee: Daicel Chemical Industries, Ltd.Inventors: Tohru Shibata, Hajime Namikoshi, Ichiro Okamoto
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Patent number: 5142034Abstract: Process for reducing the degree of substitution of cellulose esters employing Lewis acids as solvolysis promoters is disclosed. Novel low degree of substitution cellulose esters produced by the invention process are also described.Type: GrantFiled: April 16, 1990Date of Patent: August 25, 1992Assignee: Eastman Kodak CompanyInventors: Michael Bellas, Charles M. Buchanan, Kevin J. Edgar, Ted C. Germroth, Alan K. Wilson
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Patent number: 5093489Abstract: A modified cellulose and/or chitin for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein Cell is cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, R" is H or R, Z corresponds to the following groups of atoms: SR", SO.sub.3 H and salts thereof, SO-R, SONR".sub.2, SO.sub.2 -R, SO.sub.2 NR".sub.2, SO.sub.2 H and salts thereof, F, Cl, Br, I, NR".sub.2, PR".sub.2, PO.sub.3 H.sub.2 and salts thereof, PO.sub.2 H(OR), PO(OR).sub.2, PO.sub.2 HR" and salts thereof, POR"(OR) and POR".sub.2, x+t=0.75 to 2.85, t=0 to 2.85, x=0 to 2.85, and z=0.01 to 0.45. A process for preparation of the cellulose and/or chitin derivatives is also disclosed.Type: GrantFiled: October 19, 1990Date of Patent: March 3, 1992Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 5093486Abstract: A modified cellulose and/or chitin for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein cell is unmodified cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, m=0.75 to 2.85, and x=0.005 to 2.10. A process for preparation of the cellulose and/or chitin derivatives is also disclosed.Type: GrantFiled: October 19, 1990Date of Patent: March 3, 1992Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 5093488Abstract: A modified cellulose and/or chitin for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein cell is cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, R" is H or R, R"' denotes R, x+t=0.75 to 2.85, t=0 to 2.85, x=0 to 2.85, and r=0 to 1. A process for preparation of the cellulose and/or chitin derivatives is also disclosed.Type: GrantFiled: October 19, 1990Date of Patent: March 3, 1992Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 5026841Abstract: Process for the preparation of finely divided porous cellulose in the form of essentially spherical particles by formation of a suspension, in which an organic solution of a cellulose ester of aromatic or aromatic-aliphatic carboxylic acids containing a C.sub.5 -C.sub.12 alkanol is stirred into an aqueous solution of an anionic surfactant, the solvent is removed and the particles are isolated and hydrolyzed under heterogeneous conditions. They are suitable as adsorbents in e.g. chromatographic processes.Type: GrantFiled: June 16, 1989Date of Patent: June 25, 1991Assignee: Ciba-Geigy CorporationInventors: Eric Francotte, Gabriele Baisch
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Patent number: 5008385Abstract: Cellulose derivatives are disclosed which have the following formula: ##STR1## wherein Z is selected from the group consisting of alkylene, alkenylene, alkynylene, cycloalkylene or benzylene or xylylene radicals, which may or may not be substituted;X is selected from the group consisting of --H, --NR.sub.2, --N.sup.+ R.sub.3, --CN, --COOH, --SO.sub.3 H, --SO.sub.3 H, --PO(OR).sub.2, CONR.sub.2 or --Si(OR).sub.3 ;R is selected from the group consisting of hydrogen, alkyl and alkenyl groups having from 1 to 25 carbon atoms, and cycloalkyl, tolyl and phenyl groups;Y is selected from the group consisting of alkyl, alkenyl, alkynyl groups having from 1 to 36 carbon atoms, which may or may not be substituted, cycloalkyl, phenyl, tolyl and benzyl groups, ##STR2## (--CH.dbd.CH--COOH), and NHR, where R has the same meaning as in X, andm=0 to 2.5n=0.01 to 2.95,with the provision that, when m=0, n.gtoreq.1.55, if Y is an alkyl radical with 1 to 5 carbon atoms, 3-(CH.sub.2).sub.Type: GrantFiled: July 15, 1988Date of Patent: April 16, 1991Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 4997935Abstract: A modified cellulose for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein cell is cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, R" is H or R, R"' denotes R, x+t=0.75 to 2.85, t=0 to 2.85, x=0 to 2.85, and r=0 to 1. A process for preparation of the cellulose derivatives is also disclosed.Type: GrantFiled: February 27, 1989Date of Patent: March 5, 1991Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 4981959Abstract: A modified cellulose for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein cell is unmodified cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, m=0.75 to 2.85, and x=0.005 to 2.10. A process for preparation of the cellulose derivatives is also disclosed.Type: GrantFiled: February 27, 1989Date of Patent: January 1, 1991Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 4981960Abstract: A modified cellulose for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein Cell is cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH.sub.3 and/or C.sub.2 H.sub.5 and/or C.sub.3 H.sub.7, X denotes specified functional groups, R" is H or R, Z corresponds to the following groups of atoms: SR", SO.sub.3 H and salts thereof, SO-R, SONR".sub.2, SO.sub.2 -R, SO.sub.2 NR".sub.2, SO.sub.2 H and salts thereof, F, Cl, Br, I, NR".sub.2, PR".sub.2, PO.sub.3 H.sub.2 and salts thereof, PO.sub.2 H(OR), PO(OR).sub.2, PO.sub.2 HR" and salts thereof, POR"(OR) and POR".sub.2, x+t=0.75 to 2.85, t=0 to 2.85, x=0 to 2.85, and z=0.01 to 0.45. A process for preparation of the cellulose derivatives is also disclosed.Type: GrantFiled: February 27, 1989Date of Patent: January 1, 1991Assignee: Akzo N.V.Inventor: Michael Diamantoglou
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Patent number: 4935458Abstract: A release agent comprising a polyfunctional alkoxysiloxane and an organic compound which is solid at room temperature and contains a functional group capable of reacting with said polyfunctional alkoxysiloxane, and a composite material comprising a substrate and a cured film of the release agent are disclosed. The cured film of the release agent exhibits high strength and excellent release properties without causing blocking or contamination on an adherent.Type: GrantFiled: January 18, 1989Date of Patent: June 19, 1990Assignee: Nitto Denko CorporationInventors: Kihachi Suzuki, Makoto Sunakawa, Hiroshi Yamamoto
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Patent number: 4786415Abstract: A separation agent essentially comprises an aliphatic or aromatic ester of a polysaccharide, except for cellulose acetate and an aromatic ester of cellulose. It is useful for separation of various chemical substances, especially optical resolution of optical isomers.Type: GrantFiled: February 18, 1987Date of Patent: November 22, 1988Assignee: Daicel Chemical Industries, Ltd.Inventors: Tohru Shibata, Hajime Namikoshi, Ichiro Okamoto
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Patent number: 4590265Abstract: The present invention provides a novel cellulosic material and a process for preparing the same. The cellulosic material is a carboxylated cellulose ester material having an acid number of at least about 5, an inherent viscosity of from about 0.01 to about 1.00 and wherein the anhydroglucose units thereof have ring substituents comprising by weight based on total polymer weight, of from about 0.05 to about 20% hydroxyl groups, from about 0.5 to about 44% acetyl groups, from 0 to about 54% butyryl groups, from 0 to about 47% propionyl groups, from about 0.4 to about 4.0% total carboxyl groups wherein from about 20% to about 100% of these carboxyl groups are non-saponifiable backbone, and wherein the material has a lactone level of from about 4.52.times.10.sup.-5 to about 6.13.times.10.sup.-4. The carboxylated cellulose esters of the present invention are prepared by reacting a cellulose ester with ozone at a temperature of about 25.degree. to 80.degree. C.Type: GrantFiled: April 18, 1985Date of Patent: May 20, 1986Assignee: Eastman Kodak CompanyInventors: Richard T. Bogan, Chung-Ming Kuo
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Patent number: 4543409Abstract: The invention refers to water-insoluble fibers of cellulose acetate cellulose propionate and cellulose butyrate with an extremely high absorptive capacity for water and physiological liquids and to a process for their preparation.Type: GrantFiled: December 12, 1983Date of Patent: September 24, 1985Assignee: AKZO NVInventors: Michael Diamantoglou, Alexander Brandner, Gerhard Meyer
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Patent number: 4480090Abstract: The present invention relates to a method of preparing lower fatty acid esters of cellulose which comprises esterifying at a temperature of between about 75.degree. C. and about 110.degree. C. a cellulose compound having esterifiable hydroxyl groups with an esterifying bath comprising an organic acid anhydride, a diluent, and a catalyst comprising from 0.2 to 2.0 parts phosphoric acid, from 0.1 to 1.2 parts sulfuric acid, and from 0.05 to 0.6 parts of a hindered aliphatic alcohol by weight per 100 parts of the cellulose to be esterified.Type: GrantFiled: October 21, 1983Date of Patent: October 30, 1984Assignee: Eastman Kodak CompanyInventors: Chung-Ming Kuo, Alan P. Leonard
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Patent number: 4461892Abstract: A process for preparing porous, spherical cellulose particles which comprises suspending a cellulose organic ester solution dissolved in a chlorinated hydrocarbon solvent into an aqueous medium to form droplets of the solution, evaporating the chlorinated hydrocarbon solvent in the droplets to form cellulose organic ester spherical particles, and saponifying the cellulose organic ester spherical particles. In the aforesaid process, an acid or alkaki is added and mixed with the cellulose organic ester solution prior to suspending the cellulose organic ester solution into the aqueous medium to control the porosity of the porous, spherical cellulose particles with high reproducibility.Type: GrantFiled: February 23, 1983Date of Patent: July 24, 1984Assignee: Chisso CorporationInventors: Masahiko Nishikawa, Hiroaki Ishibashi, Hidenori Furukawa
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Patent number: 4390691Abstract: A process for preparing porous, spherical cellulose particles which comprises suspending a cellulose organic ester solution dissolved in a chlorinated hydrocarbon solvent into an aqueous medium to form droplets of the solution, evaporating the chlorinated hydrocarbon solvent in the droplets to form cellulose organic ester spherical particles, and saponifying the cellulose organic ester spherical particles. In the aforesaid process, an acid or alkali is added and mixed with the cellulose organic ester solution prior to suspending the cellulose organic ester solution into the aqueous medium to control the porosity of the porous, spherical cellulose particles with high reproducibility.Type: GrantFiled: July 21, 1981Date of Patent: June 28, 1983Assignee: Chisso CorporationInventors: Masahiko Nishikawa, Hiroaki Ishibashi, Hidenori Furukawa
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Patent number: 4362868Abstract: Plasticized cellulose polymers comprise a base polymer having a chain of .beta.-anhydroglucose units joined by ether linkages and having ether substituents, with at least one of the units being additionally substituted, by esterification of at least one hydroxyl group, by at least one ester group, which contains at least two carbon atoms and is chemically unreactive.Preferably the ester group contains four or more, most preferably five, carbon atoms. The carbon chains of the ester groups may be straight or branched.These internally plasticized celluloses may be prepared by, for example, reacting the base polymer with a carboxylic acid in xylene or with an acid chloride or anhydride in pyridine. They are useful in particular as inhibitor coatings for rocket motor propellants and in general wherever cellulose polymers are employed.Type: GrantFiled: September 19, 1980Date of Patent: December 7, 1982Assignee: The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britian and Northern IrelandInventors: Michael Burnup, Gerard F. Hayes, Norman C. Paul
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Patent number: 4166809Abstract: Cellulose propionate n-butyrate adapted to be mixed with an oil-modified alkyd resin to form a coating composition. The cellulose propionate n-butyrate has unique properties as an ingredient in such coating composition. The cellulose ester has a n-butyryl content of between about 3% and about 5%, a propionyl content of between about 40% and about 50% and a hydroxyl content of between about 2% and about 3%. The coating compositions are especially useful for protection and appearance when used as a coating on such items as wooden furniture.Type: GrantFiled: December 22, 1977Date of Patent: September 4, 1979Assignee: Eastman Kodak CompanyInventors: Richard J. Brewer, Willis C. Wooten, Jr.
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Patent number: 4140135Abstract: This invention provides coated tobacco product having a hydrophobic coating on at least one surface thereof, the coating comprising a cellulose propionate having an acetyl content of less than about 6% by weight, a hydroxyl content of at least 1.5% by weight, and a content of acyl groups of more than about 3 carbon atoms of less than about 10% by weight. The coating preferably comprises a mixture of the aforesaid cellulose propionate with a glyceride having the general formula: ##STR1## wherein preferably one of the R groups is a group selected from the group consisting of acetyl and propionyl, at least another R residue group represents an acyl containing at least about 12 carbon atoms, any remaining R group is hydrogen. The coating composition is applied, e.g. to a reconstituted tobacco product, as a clear solution in a volatile solvent. The volatile solvents which are suitable include alcohol-water mixtures, esters, and anhydrous alcohol-ester mixtures.Type: GrantFiled: December 29, 1975Date of Patent: February 20, 1979Assignee: Gulf & Western CorporationInventor: Frederick D. Godfrey, Jr.
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Patent number: 4038253Abstract: It has been found that certain polymers containing pendant diazo ester groups are photosensitive and have utility in the preparation of both lithographic and relief printing plates, as well as for etching resists for printed circuits. This is a continuation of application Ser. No. 412,218, filed Nov. 2, 1973 now abandoned.Type: GrantFiled: June 2, 1976Date of Patent: July 26, 1977Assignee: Hercules IncorporatedInventor: Brian D. Kramer
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Patent number: 4011205Abstract: A reactive matrix comprises a co-enzyme chemically attached to a water insoluble organic polymeric support material. The reactive matrix may be used in a process for the separation of mixtures containing a plurality of enzymes.Type: GrantFiled: September 2, 1975Date of Patent: March 8, 1977Inventors: Peter Duncan Goodearl Dean, Christopher Robin Lowe
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Patent number: 4000126Abstract: A translucent film having good water permeability and having dissociating power with respect to metallic ions is produced by subjecting one side of a cellulose film to acetylation treatment so as to highly acetylate said one side while leaving the other side unacetylated.Type: GrantFiled: March 31, 1975Date of Patent: December 28, 1976Assignee: Agency of Industrial Science & TechnologyInventor: Tsutomu Nakagawa