An antibacterial cleaning composition containing at least a surfactant, excluding cationic surfactants, a polyethylene oxide polycarboxylic acid copolymer and water.

The present invention relates to an antimicrobial cleaning composition for cleaning surfaces which provides a lasting antibacterial protection on the surface being cleaned, wherein the composition includes a polyethylene oxide polycarboxylate copolymer, polyhexamethylene biguanide hydrochloride, optionally, a surfactant and water.
Poly(hexamethylene biguanide)hydrochloride has been used in the food industry as an antibacterial solution for equipment disinfection but these solutions exhibit poor substantivity.
Numerous cleaning compositions have been disclosed in various patents. However, a major problem with these cleaning compositions is that bacteria is not effectively killed on the surface being treated and no protection is provided on the surface against the future growth of bacteria.
Poly(hexamethylene biguanide)hydrochloride has been used in combination with a cationic surfactant such as didecyl dimethyl ammonium chloride in laundry compositions but the substantivity of these laundry compositions is inferior.
Patent applications WO99/40791 and EPO891712A1 comprises a substantive antibacterial solution containing silver ions, poly(hexamethylene biguanide)hydrochloride which is crosslinked by sodium lauryl sulfate.
Avecia Limited of England also provides poly(hexamethylene biguanide)stearate for soap bars.
EP-0875554 teaches the use of an acid-stable polymer selected from the group consisting of a polycarboxylate, a sulphonated polystyrene polymer, a vinylpyrrolidone homo/copolymer, a polyalkoxylene glycol, and mixture thereof, in a liquid acidic composition having a pH below 5. Said acidic compositions are suitable for removing limescale-containing stains from a hard-surface.
EP-0983294 describes a liquid composition having a pH of from 7 to 14 for cleaning hard surfaces, comprising a homo or copolymer of vinylpyrrolidone and a polysaccharide polymer. However, no liquid neutral pH compositions as described in the present invention comprising a polyalkylene oxide polycarboxylate copolymer are disclosed therein.
The exploitation of interpolyelectrolyte reaction (PHMB with polyacrylic acid) has already been exploited to prepare antimicrobial fibres, but in this case the anionic polymer was chemically grafted on the cellulose (Virnik A. D., Penenzhik M. A., Grishin M. A., Rishkina I. S., Zezin A. B., Rogacheva V. B. 1994. Interpolyelectrolyte reactions between polyhexamethylene guanidine and polyacrylic acid grafted on cellulose: a new method for the preparation of antimicrobial fibrous material. Cellulose Chem. Technol. 28, 11-19).
The present invention relates to an antimicrobial cleaning composition having improved substantivity which comprises a polyhexamethylene biguanide hydrochloride, a polyethylene oxide polycarboxylate copolymer, optionally a surfactant selected from the group consisting of anionic, zwitterionic surfactants and nonionic surfactants and mixtures thereof, and water, wherein the composition does not contain silicon containing polymer, amino containing polymers, copolymers of polyvinyl pyrrolidone or polyvinyl pyrridine N-oxide polymers.
It is an object of the instant invention to provide an antibacterial cleaning composition, wherein the polymer links with the polyhexamethylene biguanide hydrochloride and the surface to improve the deposition and the resistance to rinse off of the polyhexamethylene biguanide hydrochloride from the surface being cleaned.
The present invention relates to a hard surface cleaning composition which renders the surface being treated resistant to the growth of bacteria, wherein the composition comprises approximately by weight:
(a) 0 to 10%, more preferably 0.1% to 5% of at least one surfactant, selected from the group consisting of anionic surfactants, amine oxide surfactants, zwitterionic surfactants and nonionics and mixtures thereof;
(b) 0.01% to 5%, more preferably 0.1% to 3% of a polymer which is a polyethylene oxide polycarboxylate copolymer;
(c) 0.01% to 5%, more preferably 0.01% to 1% of polyhexamethylene biguanide hydrochloride; and
(d) the balance being water, wherein the composition does not contain an amino containing polymer, a silicon containing polymer, a cationic surfactant, a copolymer of polyvinyl pyrrolidone or polyvinyl pyrridine N-oxide polymers.
The zwitterionic surfactant used is a water soluble betaine having the general formula
wherein Xxe2x80x94 is selected from the group consisting of COOxe2x80x94 and SO3xe2x80x94and R1 is an alkyl group having 10 to about 20 carbon atoms, preferably 12 to 16 carbon atoms, or the amido radical:
wherein R is an alkyl group having about 9 to 19 carbon atoms and a is the integer 1 to 4; R2 and R3 are each alkyl groups having 1 to 3 carbons and preferably 1 carbon; R4 is an alkylene or hydroxyalkylene group having from 1 to 4 carbon atoms and, optionally, one hydroxyl group. Typical alkyldimethyl betaines include decyl dimethyl betaine or 2-(N-decyl-N, N-dimethyl-ammonia)acetate, coco dimethyl betaine or 2-(N-coco N, N-dimethylammonia)acetate, myristyl dimethyl betaine, palmityl dimethyl betaine, lauryl dimethyl betaine, cetyl dimethyl betaine, stearyl dimethyl betaine, etc. The amidobetaines similarly include cocoamidoethylbetaine, cocoamidopropyl betaine and the like. The amidosulfobetaines include cocoamidoethylsulfobetaine, cocoamidopropyl sulfobetaine and the like. A preferred betaine is coco (C8-C18) amidopropyl dimethyl betaine. Three preferred betaine surfactants are Empigen BS/CA from Albright and Wilson, Rewoteric AMB 13 and Goldschmidt Betaine L7.
Regarding the anionic surfactant present in the compositions any of the conventionally used water-soluble anionic surfactants or mixtures of said anionic surfactants can be used in this invention. As used herein the term xe2x80x9canionic surfactantxe2x80x9d is intended to refer to the class of anionic and mixed anionic-nonionic detergents providing detersive action.
Suitable water-soluble non-soap, anionic surfactants include those surface-active or detergent compounds which contain an organic hydrophobic group containing generally 8 to 26 carbon atoms and preferably 10 to 18 carbon atoms in their molecular structure and at least one water-solubilizing group selected from the group of sulfonate, sulfate and carboxylate so as to form a water-soluble detergent. Usually, the hydrophobic group will include or comprise a C8-C22 alkyl, alkyl or acyl group. Such surfactants are employed in the form of water-soluble salts and the salt-forming cation usually is selected from the group consisting of sodium, potassium, ammonium, magnesium and mono-, di- or tri-C2-C3 alkanolammonium, with the sodium, magnesium and ammonium cations again being preferred.
The anionic surfactants which may be used in the composition of this invention are water soluble and include the sodium, potassium, ammonium and ethanolammonium salts of linear C8-C16 alkyl benzene sulfonates, alkyl ether carboxylates, C10-C20 paraffin sulfonates, C8-C18 alkyl sulfates, alkyl ether sulfates and mixtures thereof.
The paraffin sulfonates may be monosulfonates or di-sulfonates and usually are mixtures thereof, obtained by sulfonating paraffins of 10 to 20 carbon atoms. Preferred paraffin sulfonates are those of C12-18 carbon atoms chains, and more preferably they are of C14-17 chains. Paraffin sulfonates that have the sulfonate group(s) distributed along the paraffin chain are described in U.S. Pat. Nos. 2,503,280; 2,507,088; 3,260,744; and 3,372,188; and also in German Patent 735,096. Such compounds may be made to specifications and desirably the content of paraffin sulfonates outside the C14-17 range will be minor and will be minimized, as will be any contents of di- or poly-sulfonates.
Examples of suitable other sulfonated anionic detergents are the well known higher alkyl mononuclear aromatic sulfonates, such as the higher alkylbenzene sulfonates containing 9 to 18 or preferably 9 to 16 carbon atoms in the higher alkyl group in a straight or branched chain, or C8-15 alkyl toluene sulfonates. A preferred alkylbenzene sulfonate is a linear alkylbenzene sulfonate having a higher content of 3-phenyl (or higher) isomers and a correspondingly lower content (well below 50%) of 2-phenyl (or lower) isomers, such as those sulfonates wherein the benzene ring is attached mostly at the 3 or higher (for example 4, 5, 6 or 7) position of the alkyl group and the content of the isomers in which the benzene ring is attached in the 2 or 1 position is correspondingly low. Preferred materials are set forth in U.S. Pat. No. 3,320,174, especially those in which the alkyls are of 10 to 13 carbon atoms. Other suitable anionic surfactants are the olefin sulfonates, including long-chain alkene sulfonates, long-chain hydroxyalkane sulfonates or mixtures of alkene sulfonates and hydroxyalkane sulfonates. These olefin sulfonate detergents may be prepared in a known manner by the reaction of sulfur trioxide (SO3) with long-chain olefins containing 8 to 25, preferably 12 to 21 carbon atoms and having the formula RCHxe2x95x90CHR1 where R is a higher alkyl group of 6 to 23 carbons and R1 is an alkyl group of 1 to 17 carbons or hydrogen to form a mixture of sultones and alkene sulfonic acids which is then treated to convert the sultones to sulfonates. Preferred olefin sulfonates contain from 14 to 16 carbon atoms in the R alkyl group and are obtained by sulfonating an a-olefin.
Examples of satisfactory anionic sulfate surfactants are the alkyl sulfate salts and the and the alkyl ether polyethenoxy sulfate salts having the formula R(OC2H4)n OSO3M wherein n is 1 to 12, preferably 1 to 5, and R is an alkyl group having about 8 to about 18 carbon atoms, more preferably 12 to 15 and natural cuts, for example, C12-14 or C12-16 and M is a solubilizing cation selected from the group consisting of sodium, potassium, ammonium, magnesium and mono-, di- and triethanol ammonium ions. The alkyl sulfates may be obtained by sulfating the alcohols obtained by reducing glycerides of coconut oil or tallow or mixtures thereof and neutralizing the resultant product.
The ethoxylated alkyl ether sulfate may be made by sulfating the condensation product of ethylene oxide and C8-18 alkanol, and neutralizing the resultant product. The ethoxylated alkyl ether sulfates differ from one another in the number of carbon atoms in the alcohols and in the number of moles of ethylene oxide reacted with one mole of such alcohol. Preferred alkyl ether sulfates contain 12 to 15 carbon atoms in the alcohols and in the alkyl groups thereof, e.g., sodium myristyl (3 EO) sulfate.
Ethoxylated C8-18 alkylphenyl ether sulfates containing from 2 to 6 moles of ethylene oxide in the molecule are also suitable for use in the invention compositions. These detergents can be prepared by reacting an alkyl phenol with 2 to 6 moles of ethylene oxide and sulfating and neutralizing the resultant ethoxylated alkylphenol.
Other suitable anionic detergents are the C9-C15 alkyl ether polyethenoxyl carboxylates having the structural formula R(OC2H4)nOX COOH wherein n is a number from 4 to 12, preferably 6 to 11 and X is selected from the group consisting of CH2, C(O)R1 and
wherein R1 is a C1-C3 alkylene group. Preferred compounds include C9-C11 alkyl ether polyethenoxy (7-9) C(O) CH2CH2COOH, C13-C15 alkyl ether polyethenoxy (7-9)
and C10-C12 alkyl ether polyethenoxy (5-7) CH2COOH. These compounds may be prepared by condensing ethylene oxide with appropriate alkanol and reacting this reaction product with chloracetic acid to make the ether carboxylic acids as shown in U.S. Pat. No. 3,741,911 or with succinic anhydride or phtalic anhydride.
Obviously, these anionic detergents will be present either in acid form or salt form depending upon the pH of the final composition, with the salt forming cation being the same as for the other anionic detergents.
The amine oxide is depicted by the formula:
wherein R1 is an alkyl, 2-hydroxyalkyl, 3-hydroxyalkyl, or 3-alkoxy-2-hydroxypropyl radical in which the alkyl and alkoxy, respectively, contain from about 8 to about 18 carbon atoms; R2 and R3 are each methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 2-hydroxypropyl, or 3-hydroxypropyl; and n is from 0 to about 10. Particularly preferred are amine oxides of the formula:
wherein R1 is a C12-18 alkyl and R2 and R3 are methyl or ethyl. The above ethylene oxide condensates, amides, and amine oxides are more fully described in U.S. Pat. No. 4,316,824 (Pancheri), incorporated herein by reference. An especially preferred amine oxide is depicted by the formula:
wherein R1 is a saturated or unsaturated alkyl group having about 6 to about 24 carbon atoms, R2 is a methyl group, and R3 is a methyl or ethyl group. The preferred amine oxide is cocoamidopropyl-dimethylamine oxide.
The water soluble nonionic surfactants utilized in this invention are commercially well known and include the primary aliphatic alcohol ethoxylates, secondary aliphatic alcohol ethoxylates, alkylphenol ethoxylates and ethylene-oxide-propylene oxide condensates on primary alkanols, such a Plurafacs (BASF) and condensates of ethylene oxide with sorbitan fatty acid esters such as the Tweens (ICI). The nonionic synthetic organic detergents generally are the condensation products of an organic aliphatic or alkyl aromatic hydrophobic compound and hydrophilic ethylene oxide groups. Practically any hydrophobic compound having a carboxy, hydroxy, amido, or amino group with a free hydrogen attached to the nitrogen can be condensed with ethylene oxide or with the polyhydration product thereof, polyethylene glycol, to form a water-soluble nonionic detergent. Further, the length of the polyethenoxy chain can be adjusted to achieve the desired balance between the hydrophobic and hydrophilic elements.
The nonionic surfactant class includes the condensation products of a higher alcohol (e.g., an alkanol containing about 8 to 18 carbon atoms in a straight or branched chain configuration) condensed with about 5 to 30 moles of ethylene oxide, for example, lauryl or myristyl alcohol condensed with about 16 moles of ethylene oxide (EO), tridecanol condensed with about 6 to moles of EO, myristyl alcohol condensed with about 10 moles of EO per mole of myristyl alcohol, the condensation product of EO with a cut of coconut fatty alcohol containing a mixture of fatty alcohols with alkyl chains varying from 10 to about 14 carbon atoms in length and wherein the condensate contains either about 6 moles of EO per mole of total alcohol or about 9 moles of EO per mole of alcohol and tallow alcohol ethoxylates containing 6 EO to 11 EO per mole of alcohol.
A preferred group of the foregoing nonionic surfactants are the Neodol ethoxylates (Shell Co.), which are higher aliphatic, primary alcohol containing about 9-15 carbon atoms, such as C9-C11 alkanol condensed with 2.5 to 10 moles of ethylene oxide (NEODOL 91-2.5 OR-5 OR -6 OR -8), C12-13 alkanol condensed with 6.5 moles ethylene oxide (Neodol 23-6.5), C12-15 alkanol condensed with 12 moles ethylene oxide (Neodol 25-12), C14-15 alkanol condensed with 13 moles ethylene oxide (Neodol 45-13), and the like.
Additional satisfactory water soluble alcohol ethylene oxide condensates are the condensation products of a secondary aliphatic alcohol containing 8 to 18 carbon atoms in a straight or branched chain configuration condensed with 5 to 30 moles of ethylene oxide. Examples of commercially available nonionic detergents of the foregoing type are C11-C15 secondary alkanol condensed with either 9 EO (Tergitol 15-S-9) or 12 EO (Tergitol 15-S-12) marketed by Union Carbide.
Other suitable nonionic surfactants include the polyethylene oxide condensates of one mole of alkyl phenol containing from about 8 to 18 carbon atoms in a straight- or branched chain alkyl group with about 5 to 30 moles of ethylene oxide. Specific examples of alkyl phenol ethoxylates include nonyl phenol condensed with about 9.5 moles of EO per mole of nonyl phenol, dinonyl phenol condensed with about 12 moles of EO per mole of phenol, dinonyl phenol condensed with about 15 moles of EO per mole of phenol and di-isoctylphenol condensed with about 15 moles of EO per mole of phenol. Commercially available nonionic surfactants of this type include Igepal CO-630 (nonyl phenol ethoxylate) marketed by GAF Corporation.
Also among the satisfactory nonionic surfactants are the water-soluble condensation products of a C8-C20 alkanol with a heteric mixture of ethylene oxide and propylene oxide wherein the weight ratio of ethylene oxide to propylene oxide is from 2.5:1 to 4:1, preferably 2.8:1 to 3.3:1, with the total of the ethylene oxide and propylene oxide (including the terminal ethanol or propanol group) being from 60-85%, preferably 70-80%, by weight. Such detergents are commercially available from BASF-Wyandotte and a particularly preferred detergent is a C10-C16 alkanol condensate with ethylene oxide and propylene oxide, the weight ratio of ethylene oxide to propylene oxide being 3:1 and the total alkoxy content being about 75% by weight.
Condensates of 2 to 30 moles of ethylene oxide with sorbitan mono- and tri-C10-C20 alkanoic acid esters having a HLB of 8 to 15 also may be employed as the nonionic detergent ingredient in the described composition. These surfactants are well known and are available from Imperial Chemical Industries under the Tween trade name. Suitable surfactants include polyoxyethylene (4) sorbitan monolaurate, polyoxyethylene (4) sorbitan monostearate, polyoxyethylene (20) sorbitan trioleate and polyoxyethylene (20) sorbitan tristearate.
Other suitable water-soluble nonionic surfactants are marketed under the trade name xe2x80x9cPluronicsxe2x80x9d. The compounds are formed by condensing ethylene oxide with a hydrophobic base formed by the condensation of propylene oxide with propylene glycol. The molecular weight of the hydrophobic portion of the molecule is of the order of 950 to 4000 and preferably 200 to 2,500. The addition of polyoxyethylene radicals to the hydrophobic portion tends to increase the solubility of the molecule as a whole so as to make the surfactant water-soluble. The molecular weight of the block polymers varies from 1,000 to 15,000 and the polyethylene oxide content may comprise 20% to 80% by weight. Preferably, these surfactants will be in liquid form and satisfactory surfactants are available as grades L 62 and L 64.
The alkyl polysaccharides surfactants, which are used in the instant composition with the aforementioned surfactants have a hydrophobic group containing from about 8 to about 20 carbon atoms, preferably from about 10 to about 16 carbon atoms, most preferably from about 12 to about 14 carbon atoms, and polysaccharide hydrophilic group containing from about 1.5 to about 10, preferably from about 1.5 to about 4, most preferably from about 1.6 to about 2.7 saccharide units (e.g., galactoside, glucoside, fructoside, glucosyl, fructosyl; and/or galactosyl units). Mixtures of saccharide moieties may be used in the alkyl polysaccharide surfactants. The number x indicates the number of saccharide units in a particular alkyl polysaccharide surfactant. For a particular alkyl polysaccharide molecule x can only assume integral values. In any physical sample of alkyl polysaccharide surfactants there will be in general molecules having different x values. The physical sample can be characterized by the average value of x and this average value can assume non-integral values. In this specification the values of x are to be understood to be average values. The hydrophobic group (R) can be attached at the 2-, 3-, or 4- positions rather than at the 1-position, (thus giving e.g. a glucosyl or galactosyl as opposed to a glucoside or galactoside). However, attachment through the 1-position, i.e., glucosides, galactoside, fructosides, etc., is preferred. In the preferred product the additional saccharide units are predominately attached to the previous saccharide unit""s 2-position. Attachment through the 3-, 4-, and 6-positions can also occur. Optionally and less desirably there can be a polyalkoxide chain joining the hydrophobic moiety (R) and the polysaccharide chain. The preferred alkoxide moiety is ethoxide.
Typical hydrophobic groups include alkyl groups, either saturated or unsaturated, branched or unbranched containing from about 8 to about 20, preferably from about 10 to about 18 carbon atoms. Preferably, the alkyl group is a straight chain saturated alkyl group. The alkyl group can contain up to 3 hydroxy groups and/or the polyalkoxide chain can contain up to about 30, preferably less than about 10, alkoxide moieties.
Suitable alkyl polysaccharides are decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, and octadecyl, di-, tri-, tetra-, penta-, and hexaglucosides, galactosides, lactosides, fructosides, fructosyls, lactosyls, glucosyls and/or galactosyls and mixtures thereof.
The alkyl monosaccharides are relatively less soluble in water than the higher alkyl polysaccharides. When used in admixture with alkyl polysaccharides, the alkyl monosaccharides are solubilized to some extent. The use of alkyl monosaccharides in admixture with alkyl polysaccharides is a preferred mode of carrying out the invention. Suitable mixtures include coconut alkyl, di-, tri-, tetra-, and pentaglucosides and tallow alkyl tetra-, penta-, and hexaglucosides.
The preferred alkyl polysaccharides are alkyl polyglucosides having the formula
R2O(CnH2nO)r(Z)x
wherein Z is derived from glucose, R is a hydrophobic group selected from the group consisting of alkyl, alkylphenyl, hydroxyalkylphenyl, and mixtures thereof in which said alkyl groups contain from about 10 to about 18, preferably from about 12 to about 14 carbon atoms; n is 2 or 3 preferably 2, r is from 0 to 10, preferable 0; and x is from 1.5 to 8, preferably from 1.5 to 4, most preferably from 1.6 to 2.7. To prepare these compounds a long chain alcohol (R2OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (R1OH) can be reacted with glucose, in the presence of an acid catalyst to form the desired glucoside. Alternatively the alkyl polyglucosides can be prepared by a two step procedure in which a short chain alcohol (C1-6) is reacted with glucose or a polyglucoside (x=2 to 4) to yield a short chain alkyl glucoside (x=1 to 4) which can in turn be reacted with a longer chain alcohol (R2OH) to displace the short chain alcohol and obtain the desired alkyl polyglucoside. If this two step procedure is used, the short chain alkylglucosde content of the final alkyl polyglucoside material should be less than 50%, preferably less than 10%, more preferably less than about 5%, most preferably 0% of the alkyl polyglucoside.
The amount of unreacted alcohol (the free fatty alcohol content) in the desired alkyl polysaccharide surfactant is preferably less than about 2%, more preferably less than about 0.5% by weight of the total of the alkyl polysaccharide. For some uses it is desirable to have the alkyl monosaccharide content less than about 10%.
The used herein, xe2x80x9calkyl polysaccharide surfactantxe2x80x9d is intended to represent both the preferred glucose and galactose derived surfactants and the less preferred alkyl polysaccharide surfactants. Throughout this specification, xe2x80x9calkyl polyglucosidexe2x80x9d is used to include alkyl polyglycosides because the stereochemistry of the saccharide moiety is changed during the preparation reaction.
An especially preferred APG glycoside surfactant is APG 625 glycoside manufactured by the Henkel Corporation of Ambler, PA. APG25 is a nonionic alkyl polyglycoside characterized by the formula:
CnH2n+1O(C6H10O5)xH
wherein n=10 (2%); n=122 (65%); n=14 (21-28%); n=16 (4-8%) and n=18 (0.5) and x (degree of polymerization)=1.6. APG 625 has: a pH of 6 to 10 (10% of APG 625 in distilled water); a specific gravity at 25xc2x0 C. of 1.1 g/ml; a density at 25xc2x0 C. of 9.1 lbs/gallon; a calculated HLB of 12.1 and a Brookfield viscosity at 35xc2x0 C., 21 spindle, 5-10 RPM of 3,000 to 7,000 cps.
The polyhexamethylene biquanide (PHMB) used in the instant composition has the following structure:
where the average n=4 to 6
The polymer used in the instant compositions is a polyethylene oxide polycarboxylic acid copolymer having the structure of:
wherein R1 is H or methyl group, R2 is H or an alkyl group having from 1 to 4 carbons and preferably 1 carbon, the ratio of x to y is about 1:1 to 10:1, preferably 9:1, m is about 20 to 200, preferably about 90, the weight ratio of polycarboxylate to polyethylene oxide side chains is about 50/50 to 10/90 and preferably 20/80 and the molecular mass is about 20,000 to about 200,000, more preferably about 100,000. A preferred copolymer is an acrylic acid-polyethylene glycol monomethyl ether monomethacrylate copolymer sold by BASF as Sokalan HP80 or Sokalan PM70.
The surfactants, the polyethylene oxide polycarboxylic acid copolymer and polyhexamethylene biguanide hydrochloride are solubilized in the water. To the composition can also be added water soluble hydrotropic salts which include sodium, potassium, ammonium and mono-, di- and triethanolammonium salts. While the aqueous medium is primarily water, preferably said solubilizing agents are included in order to control the viscosity of the liquid composition and to control low temperature cloud clear properties. Usually, it is desirable to maintain clarity to a temperature in the range of 4xc2x0 C. to 20xc2x0 C. Therefore, the proportion of solubilizer generally will be from 0.1% to 15%, preferably 0.5% to 12%, most preferably 0.5% to 8%, by weight of the detergent composition with the proportion of ethanol, when present, being 5% of weight or less in order to provide a composition having a flash point above 46xc2x0 C. Preferably the solubilizing ingredient will be a mixture of ethanol and either sodium xylene sulfonate or sodium cumene sulfonate or a mixture of said sulfonates or ethanol and urea. Other solubilizing agents can be ethylene glycol, propylene glycol, ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether (butyl carbitol), propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monobutyl ether, mono, di, tripropylene glycol monobutyl ether, tetraetylene glycol monobutyl ether, mono, di, tripropylene glycol monomethyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monopentyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monopentyl ether, triethylene glycol monopropyl ether, triethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monopentyl ether, triethylene glycol monohexyl ether, mono, di, tripropylene glycol monopropyl ether, mono, di, tripropylene glycol monoethyl ether, mono, di, tripropylene glycol monopentyl ether, mono, di, tripropylene glycol monohexyl ether, mono, di, tributylene glycol monomethyl ether, mono, di, tributylene glycol monohexyl ether, mono, di, tributylene glycol monopropyl ether, mono, di, tributylene glycol monoethyl ether, mono, di, tributylene glycol monopentyl ether, mono, di, tributylene glycol monobutyl ether, ethylene glycol monoacetate and dipropylene glycol propionate.
Inorganic salts such as sodium sulfate, magnesium sulfate, sodium chloride and sodium citrate can be added at concentrations of 0.5 to 4.0 wt. % to control the haze of the resultant solution. Magnesium salt can be used with formulations at neutral or acidic pH since magnesium hydroxide will not precipitate at these pH levels. Various other ingredients such as urea at a concentration of 0.5 to 4.0 wt. % or urea at the same concentration of 0.5 to 4.0 wt. % can be used as solubilizing agents. Other ingredients which have been added to the compositions at concentrations of 0.01 to 4.0 wt. % are perfumes, sodium bisulfite, EDTA and HETDA. The foregoing solubilizing ingredients also facilitate the manufacture of the inventive compositions because they tend to inhibit gel formation.
The liquid compositions of the present invention have a pH of about 3 to about 8, more preferably about neutral. Thus, they may comprise as an optional ingredient a source of acidity or alkalinity for the purpose of pH adjustment. Suitable sources of acidity for use herein are lactic acid, citric acid, sulfuric acid and hydrochloric acid. Suitable sources of alkalinity for use herein are the caustic alkalis such as sodium hydroxide or potassium hydroxide.
In addition to the previously mentioned essential and optional constituents of the compositions, one may also employ normal and conventional adjuvants, provided they do not adversely affect the properties of the detergent. Thus, there may be used various coloring agents and perfumes; ultraviolet light absorbers such as the Uvinuls, which are products of GAF Corporation; sequestering agents such as ethylene diamine tetraacetates; magnesium sulfate heptahydrate; pearlescing agents and opacifiers; pH modifiers, preservatives; etc. The proportion of such adjuvant materials, in total will normally not exceed 15% of weight of the detergent composition, and the percentages of most of such individual components will be a maximum of 5% by weight and preferably less than 2% by weight.
One emulsifier used in the instant composition is LRI manufactured by Wackherr which is a mixture of a PEG-40 hydrogenated Castor oil and PPG-26 buteth 26. Other useful emulsifiers are all the surfactants that can be used to solubilize perfumes or other lipophilic ingredients into water as the surfactants belonging to the following families and showing an HLB higher than 12: the ethoxylated fatty alcohols, ethoxylated lanolin, ethoxylated glycerides or ethoxylated hydroxylated glycerides, ethoxylated amides, ethoxylated carboxylic acids (polyethylene glycol acylates and di-acylates), EO-PO block copolymers or any propoxylated PEO ethers as well as sorbitan and sorbitol esters. More specifically, the following examples can be mentionned:
Ethoxylated castor oil or ethoxylated hydrogenated castor oil as Arlatone 289, 650 and 827 from Imperial Chemical Industries; all mixtures containing ethoxylated castor oil or ethoxylated hydrogenated castor oil as Arlatone 975 and Arlatone 980 from or Imperial Chemical Industries or also the Emulsifier 2/014160 from Dragoco which is a mixture of fatty alcohol polyglycolether and hydrogenated castor oil ethoxylate; all the ethoxylated alkyl alcohol as the range of Brij surfactants from Imperial Chemical Industries or also Arlasolve 200 which is an ethoxylated isohexadecyl alcohol; all the polyethyleneglycol sorbitan mono- and tri- alkanoic acid esters from Imperial Chemical Industries, especially Tween 20 which is polyoxyethylene (20) sorbitan monolaurate.
The instant compositions are readily made by simple mixing methods from readily available components which, on storage, do not adversely affect the entire composition.
The instant composition liquids are readily made by simple mixing methods from readily available components which, on storage, do not adversely affect the entire composition.
The following examples illustrate liquid cleaning compositions of the described invention. The exemplified compositions are illustrative only and do not limit the scope of the invention. Unless otherwise specified, the proportions in the examples and elsewhere in the specification are by weight.

Antimicrobial scale cleaning composition comprising polyhexamethylene biquanide hydrochloride


A method enables a gas turbine engine to be provided. The method comprises providing a ring support that includes a first radial flange, a second radial flange, and a plurality of beams that extend therebetween, within the engine, wherein at least one of the beams is tapered between the first and second radial flanges, and coupling the ring support to a backbone frame, such that the ring support extends substantially circumferentially within the engine.

This invention relates generally to gas turbine engines, more particularly to methods and apparatus for controlling engine clearance closures.
Known turbine engines include a compressor for compressing air which is suitably mixed with a fuel and channeled to a combustor wherein the mixture is ignited for generating hot combustion gases. The gases are channeled to at least one turbine, which extracts energy from the combustion gases for powering the compressor, as well as for producing useful work, such as propelling a vehicle.
To support engine casings and components within harsh engine environments, at least some known casings and components are supported by a plurality of support rings that are coupled together to form a backbone frame. The backbone frame provides structural support for components that are positioned radially inwardly from the backbone and also provides a means for an engine casing to be coupled around the engine. In addition, because the backbone frame facilitates controlling engine clearance closures defined between the engine casing and components positioned radially inwardly from the backbone frame, such backbone frames are typically designed to be as stiff as possible.
At least some known backbone frames used with recouperated engines, include a plurality of beams that extend between forward and aft flanges. To provide structural support and stiffness for the backbone frames, the beams are sized with a width that is substantially constant along a length of the beam, such that the width is as wide as possible, while still permitting physical passage of components and/or services therebetween. The beams are also sized with a thickness that is substantially constant along the beam length, and is limited by thermal induced stresses and component low cycle fatigue (LCF) considerations. More specifically, thicker and wider beams result in a stiffer structure, but are also more susceptible to thermally induced stresses and LCF. Alternatively, thinner and less wide beams are not as susceptible to thermally induced stresses and LCF, but may not provide the necessary stiffness to control engine clearance.

Methods and apparatus for controlling engine clearance closures


A turbine blade is disclosed having a tip shroud that includes internal passages through which cooling air is flowed to minimize creep. The cooling air is provided to the shroud through dedicated cooling passageways which include tube inserts that restrict the transfer of heat from the airfoil portion of the turbine blade to the cooling air within the tube as the cooling air passes through the airfoil portion.

The present invention relates to a blade for a gas turbine, and more specifically, to the cooling of a gas turbine blade shroud.
A gas turbine is typically comprised of a compressor section, a combustor section and a turbine section. The compressor section produces compressed air. Then fuel is mixed with some of the compressed air and burned in the combustor section. The compressed, high temperature gas produced in the combustor section is then expanded through rows of stationary vanes and rotating blades in the turbine section to produce power in the form of a rotating shaft.
Each of the rotating blades has an airfoil portion and a root portion that connects it to a rotor. Since the blades are exposed to the compressed, hot gas discharging from the combustor section, the turbine blades must be cooled to prevent failure. Usually this cooling is done by taking a portion of the compressed air produced by the compressor and using it as cooling air in the turbine section to cool turbine blades. The cooling air enters each cooled turbine blade through its root, and flows through radial passageways in the airfoil portion of the blades. While in many cooled turbine blades, the radial passageways discharge the cooling air radially outward at the blade tip, some turbine blades incorporate shrouds that project outwardly from the airfoil at the blade tip. These shrouds prevent hot gas leakage past the blade tips, and may also be used to dampen blade vibration that tends to occur during normal operation of gas turbine engines. Unfortunately, excessive creep and creep failures can occur in blade shrouds due to the high operating temperatures.
While the known methods of cooling turbine blades are generally successful at cooling the airfoil portions of turbine blades, designs for cooling shrouds have produced mixed results. In some designs, cooling air discharged from the radial passages at the blade tip flows over the radially outward facing surface of the shroud. Although this provides some cooling, it is often insufficient to adequately cool the shroud due to heating of the cooling air in the airfoil passageways.
Another design includes incorporating cooling passages into each shroud, with the cooling passages extending approximately parallel to the radially inward facing surface of the shroud. These passages, which connect to one or more of the radial passageways, divert cooling air from the airfoil passageways so that it flows through the cooling passages in the shroud, thereby lowering the operating temperature of the shroud. While this method of internally cooling the shroud is generally more effective than flowing cooling air over the radially outward facing surface of the shroud, the heat transfer rate from the shroud to the cooling air in the passages may be insufficient to prevent excessive creep at certain operating conditions.
What is needed is a turbine blade having a shroud that is sufficiently cooled to prevent excessive creep at all engine operating conditions.
It is therefore an object of the present invention to provide a turbine blade having a shroud that is sufficiently cooled at all engine operating conditions to prevent the excessive creep that can occur in turbine shrouds when turbine blades are exposed to high stress and very high operating temperatures.
According to the preferred embodiment of the present invention, a turbine blade is disclosed having a root portion with a cooling fluid cavity therein, a platform connected to the root portion, an airfoil portion extending from the platform, the airfoil portion includes at least one cooling passageway extending substantially radially through the airfoil, and at least one cooling hole extending substantially radially through the airfoil, with the one cooling passageway and the cooling hole each defined by an inner wall having an inlet for receiving a flow of cooling fluid from the cavity. The turbine blade further includes a shroud projecting outwardly from the airfoil and has a radially inward facing surface, a radially outward facing surface, and a shroud edge extending therebetween, at least one cooling fluid outlet adjacent the edge, and at least one cooling passage between the radially inward facing surface and the radially outward facing surface. The cooling passage is approximately parallel to the radially inward facing surface, and a tube is located within the cooling hole. The tube has an outer wall, a first end adjacent the inlet and a second end radially outward therefrom. The cooling passage communicates with the inlet through the tube, and standoff means between the inner wall of the cooling passageway and the outer wall of the tube maintain the inner wall of said cooling passageway in spaced relation to said outer wall of the tube to minimize heat transfer between the airfoil and the tube.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings.

Insulated cooling passageway for cooling a shroud of a turbine blade


An improved dual-mode optical fiber provides for an improved combination of spectral attenuation, bending losses and modal noise and modal dispersion for long-haul transmission at 1550 nm. The dual-mode optical fiber has a pure-silica core and a silica cladding depressed with fluorine so that the core and cladding have a relative refractive index difference, .DELTA., of about 0.72% and a second-mode cutoff wavelength, .lambda..sub.c, at 1630 nm. Optionally, a non-silica core and cladding can be used for long-haul transmission at 1550 nm. when the core and cladding have a relative refractive index difference, .DELTA., of about 0.72% and a second-mode cutoff wavelength, .lambda..sub.c, at 1630 nm.

The transmission of signals through optical fibers over long distances has been made possible largely because the losses in modern glass fibers are small. The lower losses in an optical fiber as compared to a metallic cable reduce the numbers of repeaters required in a transmission length, which improves the reliability and reduces the complexity of the link. Low-loss optical fibers with high bandwidths are revolutionizing long-haul communications for both commercial and military applications.
Losses in optical fibers are determined by spectral-attenuation, which is intrinsic to the fiber design, and bending losses which result from externally applied stresses. Spectral attenuation is determined by absorption and scattering, which have been minimized over the years through improvements in the glass composition and manufacturing processes. Bending losses are the result of optical power leaking out of the optical fiber where sharp bends occur in the fiber. A consequence of these bending losses is a reduction of the allowed transmission's distance.
To prevent severe bends, optical fibers have been inserted into cables with increased reinforcement and stiffness. However, a limitation of these reinforced cables is that their design dilutes the flexibility and lightweight advantages inherent in optical fibers when compared to the metallic cables. Structural modifications of the fiber itself have been attempted in an attempt to minimize bending loss, yet, for the most part, these attempts have resulted in an undesirable increase in spectral attenuation.
Thus, a continuing need exists in the state of the art for a pure-silica-core dual-mode fiber which exhibits both low bending losses and low spectral attenuation to produce a unique capability for long-haul fiber optic transmission in severe bending environments such as those encountered in undersea cables and missile tethers.

Pure-silica core dual-mode optical fiber

The United States of America as represented by the Secretary of the Navy


A system for assessing organ function couples light emitters into an optical fiber delivery assembly of which the tip extends to or into an internal organ and illuminates tissue; the device senses temperature at the tip, and a collection fiber collects light scattered, reflected or emitted by the surrounding tissue. Control and processing modules drive the laser diodes and process return spectral signals, e.g., to assess metabolic activity and detect onset of shock. A prototype uses four laser diodes with peaks at 735, 760, 805 and 890 nm, with a front end splitter providing a reference beam to a photo detector for normalizing detection output and correcting the signal samples. The device may include a plurality of laser diodes and may select subsets of the sources to tailor spectral illumination to different target enzymes, metabolites or other compounds. The processor may include heuristic correlators for interpreting the physiological state or detecting the onset of shock based on magnitudes of multiple different measured parameters.

Not Applicable.
Not Applicable.
The present invention relates generally to the assessment of organ function and to the determination of critical events such as metabolic changes and pathologic responses that may occur within an organ. It is of particular utility for detecting adverse changes which generally become only slowly manifest in other anatomic systems such as blood chemistry, cardiovascular functioning or other indicators of health commonly monitored in a hospital setting.
For a critical care patient whose medical condition may change rapidly over time, constant monitoring of the body functions in real time is considered essential. Such assessment of patient condition is crucial in alerting a physician to potential problems. One serious and extremely dangerous but common problem is rapid blood loss that can induce shock. The onset of shock in critical care patients is swift, and may lead to death if not detected. Current monitoring techniques focus on vital signs such as heart rate or blood pressure, which may be inadequate to detect shock sufficiently early because these parameters do not change immediately upon onset of the underlying condition or provoking stimulus. A patient can lose ten percent or more of total blood volume before blood pressure is even affected.
Parameter changes within an organ such as the liver may be capable of providing a more immediate indication than is provided by circulating blood enzymes or other indicators, since the liver plays a key role in homeostasis. It is thus situated to provide more immediate indicia of critical changes. One might therefore hope that by monitoring parameter changes during hepatic shock, some parameters may be found to correlate with the onset of shock in a patient. If so, these might provide an early warning to allow appropriate intervention. Presently, however, liver condition is determined remotely and inferentially, primarily through blood analysis. Typically, liver function tests measure the ability of the liver to synthesize enough protein to regulate blood coagulation correctly. Although the results of such tests can be helpful, these assays generally involve a delay of hours between the onset of an adverse or trauma condition in the liver and the detection of its effects through blood analysis. After such a delay, the liver itself may already be damaged beyond repair. Thus, the development of a real-time monitoring system for the liver or other organ would greatly aid in the timely assessment of patient medical condition.
Accordingly, it is desirable to provide a method of assessing physiological organ parameters more directly.
It would also be desirable to provide a versatile and simple assay extendible to the detection of different critical parameters or conditions.
One or more of these and other desirable ends are achieved in accordance with the present invention by a system for assessing organ function wherein a plurality of light emitters of differing spectral characteristic are coupled into a fiber assembly including a percutaneous insertion and penetration body having at least one optical fiber signal guide. The percutaneous insertion body is adapted for insertion through a human body with at least its tip extending to or penetrating an internal organ so that it positions the fiber to illuminate organ tissue. A second (or the same) fiber catches light scattered, reflected or emitted by the surrounding tissue and returns a light signal to the proximal end of the device, where it is coupled to a detector. The device also senses temperature at the tip, either through an electrically connected sensing element such as a thermistor, or by a light-based technique such as infrared thermography, in which case one or more additional fibers adapted to carry a signal in the appropriate thermographic spectral region may be provided.
In a prototype embodiment, control and processing modules drive each of a plurality of laser diodes in succession to emit light in a plurality of different peak regions and at different times. This light is directed at organ tissue to interact therewith, and a detection fiber picks up and returns an interaction light signal for detection by a photo detector to determine the magnitude of each interaction signal. A beam splitter provides a portion of each of the emitted input signals as a reference signal to normalize the detected return values, which may, for example, correspond to the overall absorption in each band of specific substances selected in advance for their known occurrence during shock, or they may be simply spectral absorption values which are empirically determined to occur during organ failure, even if the specific absorbing substance remains unidentified.
In various embodiments, the instrument may assess general organ function or metabolic activity by detecting changes in light absorption attributable to one or more spectral bands characteristic of particular enzymes, proteins, metabolites or the like. In one prototype embodiment, absorption at a peak of deoxygenated hemoglobin and/or at one or more peaks of oxygenated hemoglobin may be monitored. Alternatively, relative absorption of signals on each side of a peak, or surrounding a specific wavelength, may be monitored as an indicator of organ change. Preferably a target pair of substancesxe2x80x94biological molecules, enzymes or metabolitesxe2x80x94are selected such that coordinated changes in different spectral regions characteristic of the pair of substances occur during shock. This allows the detection of simultaneous change in two or more distinct but associated spectral bands to be detected and more dependably correlated as an indicator of condition. The detection processing may include a time-varying detection protocol which may, for example enhance detection of a blood-flow related substance. In one embodiment, the device performs a relative discrimination of state by monitoring pulse oxygen saturation of hemoglobin in real time together with one or more other parameters such as temperature. A correlation of changes in the different monitored parameters then serves as a warning indicator of organ failure.
As applied to a prototype monitor embodiment for detecting change correlated to shock in the liver, a prototype for a body-insertable device employed four different laser diodes having peaks at 735, 760, 805 and 890 nm, and connected to a common optical fiber. The diodes were driven at output powers between about 50 to 100 mW to illuminate organ tissue, and a front-end splitter separated a portion of the beam as a reference beam that was directed to a photo detector to develop an input power signal used to normalize the level of the detection output from the return fiber. Suitable coupling for the input light signal may be obtained by collimating and focusing each diode output into a bundle whose output is then directed into the delivery fiber, or may be fabricated by fusing pairs of two hundred micrometer core diameter multimode fibers with an SMA connector as an end coupler. The return fiber for collecting an interaction signal consisting of the light collected from or through the organ tissue and returning it to the photo detector may have a collection face (such as a bevel) or a light-gathering pipe, oriented to avoid catching direct illumination. The photo detector may be a broad band detector useful over a range, for example, of 320 to 1100 nanometers. Preferably high sensitivity detectors with a detection threshold of a milliwatt or less are employed. In various embodiments, the system may be used in an absorbance, reflectance or fluorescence mode and may perform detection after filtering the input and/or return signal with one or more narrow band filters and/or band pass or cut-off filters to allow use of lesser quality light sources, or to tailor the applied or return narrow band probe wavelengths for detection of particular materials.
A physical implementation of the percutaneous monitor instrument of the present invention may be configured for catheter insertion, or may be implemented as a semi-rigid assembly having its fibers, and electrical connections if present, carried within a metal piercing sleeve that is itself capable of penetration and insertion directly through the skin and into an organ. Preferably, a control module such as a programmed microprocessor, allows the user to adjust data acquisition parameters and to view in real time the output signals as well as the measured or calculated parameters corresponding to those signals. The control module may also control the underlying signal acquisition, e.g., firing sequence and ON times of laser diodes, timing of return light signal sampling measurements, and size of samples and data stores, to optimize the capture of a meaningful measurement. In other embodiments, the instrument may be configured with a larger plurality of light sources of which only a portion are illuminated for each assay. Specific narrow band diodes may be provided effective to excite particular spectral responses or detect highly characteristic absorbances, or the diodes may collectively cover a broad spectral region with numerous smaller spectral bands. For such an instrument; the selection of particular diodes may be varied for different assays to tailor the spectral illumination to detection of a different specific intended target substances or organ conditions. The processor may include heuristic correlators or programmed interpretations and displays for indicating the physiological state based on measured magnitudes of the multiple different detected signals.

Minimally invasive system for assessment of organ function


A flotation machine is provided which includes at least one flotation cell having an inner chamber. The fiber suspension is transported into the inner chamber, and a gas is injected into the fiber suspension within the inner chamber at a temperature above 100xc2x0 C. to decrease the density of the wax within the fiber suspension. The wax is removed from the fiber suspension.

1. Field of the Invention
The present invention relates to a machine for removing contaminants from a fiber suspension, and, more particularly, to a flotation machine used for removing contaminants from a fiber suspension.
2. Description of the Related Art
A paper-making machine receives a prepared fiber suspension and produces a fiber web, such as a paper web. The fiber suspension is prepared from a source of fiber, such as wood fiber, within a stock preparation system. The stock preparation system may include a flotation machine which is used to float contaminants to the top of the suspension for removal thereof. Typically, the fiber suspension is at a relatively high temperature as a result of the various mechanical forces which are applied thereto and chemical reactions which occur therein. Contaminants within the fiber suspension in the form of particulates, such as varnish particles, dirt, etc. are relatively unaffected by the higher temperature of the fiber suspension and may be adequately floated to the top of the fiber suspension for removal. However, contaminants within the fiber suspension may also be in the form of various waxes which are contained within recycled paper. The waxes are transformed into colloidal particles within the fiber suspension at the higher temperatures at which the fiber suspension is typically transported into the flotation machine. The density of the colloidal wax particles at the temperature of the fiber suspension does not allow the wax particles to be effectively removed from the fiber suspension.
Waxes in the form of petroleum waxes have long been used in the paper converting industry to provide cellulosic paper products moisture resistance and wet strength. These paper products include corrugated boxes, paper cups, waxed paper wrapper and waxed roll-wrap laminates. Of these products, corrugated boxes account for the majority of the wax consumed. When wax is applied to corrugated boxes, the main objective is to provide board structural integrity in humid and wet environments. Examples of wax corrugated boxes are poultry boxes, vegetable boxes and fresh fruit boxes.
The majority of wax used in the corrugated board plant is paraffin wax, a by-product of the automotive lubricating oil refining process. Paraffin wax is a crystalline material composed primarily of a mixture of hydrocarbon molecules. Solid paraffin waxes are usually white, translucent tasteless and odorless. In a molten state, paraffin waxes are clear, colorless liquids of low viscosity. The melting point of paraffin waxes ranges from 43-71xc2x0 C.
Wax is applied to corrugated paperboard in three ways: a) Impregnating, by dipping or submerging paperboard into a bath of molten wax; b) Cascading, by flushing a thick xe2x80x9cwaterfallxe2x80x9d of wax into or over the finished board; and c) Curtain-coating, by passing the paperboard horizontally through a thin curtain of falling wax. The curtain-coated wax is usually a mixture of paraffin wax and other non-wax additives such as resins, rosins, polymers, and copolymers.
Waxed old corrugated container (OCC), entering through the collection process, is the largest source of wax contamination in paper recycling mills. These waxes present a major obstacle to the paper recycling industry. The problems with wax for papermaking are as follows: a) Presence of wax in a paper sheet results in the reduction of coefficient of friction, which in turn causes troubles in rewinding, converting, and box stacking; b) Waxes tend to deposit on the surface of fibers, thus lowering the interfiber bonding strength. The paper and board made from such fibers possess lower strength properties when the amount of wax in the paper and board reaches 0.5%. Also, there is some loss in stiffness; c) Paper and board containing wax generally have poor glueability; d) Non-dispersed waxes (such as curtain coating) introduce unpleasant spots in paper sheets during drying; and e) Occasionally waxes can aggravate a pitch problem. Wax tends to soften the pitch, thus making it more tacky.
Low-viscosity waxes (used for cascading or impregnating processes) are easily detached and dispersed during pulping at or above the melting point of wax. The dispersed wax forms an emulsion with water. The average size of wax particles in the emulsion is about 5 xcexcm. At this size range, conventional mechanical separation equipment, such as screen and cleaner, is not effective in removing these contaminants.
Because of the above-mentioned problems with wax, waxed OCC and other waxed paper products have been classified as non-recyclable. As such, waxed OCC is generally sorted out from the recycling plant and incinerated or landfilled. In order to utilize waxed OCC and other waxed paper products as a fiber resource for papermaking, removal of wax from the pulp suspension it necessary.
It is known to inject gas at a lower temperature into a fiber suspension within a flotation machine to clump the wax particles within the fiber suspension and thereby allow effective flotation and removal of the wax particles. However, depending upon various operating parameters such as the volumetric flow rate of the fiber suspension within the flotation machine, volumetric flow rate of the low temperature gas injected into the flotation machine, temperature of the fiber suspension and temperature of the low temperature gas, the temperature reduction of the fiber suspension within the flotation machine may not be sufficient to allow adequate clumping of the wax particles within the fiber suspension. Thus, although such a flotation machine may be adequate to remove wax for some applications, it may not provide adequate wax removal for other applications. A flotation machine which injects cold air into the fiber suspension is disclosed in U.S. patent application Ser. No. 09/595,214, entitled xe2x80x9cFLOTATION MACHINE FOR A FIBER SUSPENSION AND METHOD OF USING SAMExe2x80x9d, which is commonly assigned to the assignee of the present invention.
What is needed in the art is a flotation machine and corresponding method of operation which allow effective removal of wax contaminants within the fiber suspension.
At The present invention provides a flotation machine which injects high temperature gas into the fiber suspension to decrease the density of the colloidal wax and thereby allow the wax to be floated to the top and removed.
The invention comprises, in one form thereof, a flotation machine for removing a contaminant from a fiber suspension, including a flotation cell having an inner chamber. At least one gas injector injects a gas into the fiber suspension within the inner chamber at a temperature above 100xc2x0 C. to decrease the density of the wax within the fiber suspension and float the wax to the top of the fiber suspension. A wax removal device includes an elongate element positioned at and configured to move along a top of the inner chamber to remove contaminants from the fiber suspension.
The invention comprises, in another form thereof, a method of removing wax from a fiber suspension. A flotation machine is provided which includes at least one flotation cell having an inner chamber. The fiber suspension is transported into the inner chamber. A gas is injected into the fiber suspension within the inner chamber at a temperature above 100xc2x0 C. to decrease the density of the wax within the fiber suspension and float the wax of decreased density to the top of the fiber suspension. The wax is removed from the fiber suspension.
An advantage of the present invention is that the density of the wax within the fiber suspension is decreased, thereby allowing flotation and removal thereof.
Another advantage is that the floated wax may be removed with different types of removal devices.

Flotation machine for a fiber suspension and method of using same

Voith Sulzer Paper Technology North America, Inc.