FIBERS CONTAINING MARKER COMPOSITIONS AND CROSS-LINKED POLYMERS

Abstract: Fibers and other articles of manufacture have a near-infrared fluorescent compositions, useful as identification markers, attached to the fiber or article of manufacture by a cross-linking agent. The marker compositions may contain other ingredients, such as antistats, antimicrobials and/or other additives mixed therein. Effective cross-linking can be obtained by several means, including heating in an oven, air-drying, etc. A method for marking the fiber or article includes contacting the material with a cross-linking agent and a near-infrared fluorescing compound having an absorbance of illumination radiation ranging from about 650 nm to about 100 nm.

Description: FIBERS CONTAINING MARKER COMPOSITIONS AND CROSS-LINKED POLYMERS CROSS REFERENCE TO RELATED APPLICATIONS Priority is claimed to the earlier filed patent application having U.S. Serial No. 60/87,480 filed June 1, 1998, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to fibers and more particularly to fibers having at least one invisible near infrared fluorophore incorporated thereon. The invention further relates to a method for treating fibers so that they may be identified using an irradiation source producing a wavelength greater than about 600 nanometers (nm). Background of the Invention In the textile industry various types of fibers and materials are used in the manufacture of threads, yarns, fabrics and finished materials. Two types of fabrics known to those skilled in the art include woven fabrics and nonwoven fabrics. Nonwoven materials are manufactured by means other than by weaving or knitting. Nonwoven materials are utilized in a broad and diverse range of products, such as, absorbent pads, wiping and cleaning sheets and fabrics, insulation, liners, wicks, relatively thick battings, compressed bonded battings and webs, bandages, incontinence structures and filters and the like. Woven materials typically use a thread or yarn material and are woven into a fabric using an apparatus known to those skilled in the weaving art. Use of fluorescent agents for the tracing and identification of articles such as monitoring the integrity of the yarn or fiber during slashing, warping or weaving is described in U.S. Patent No. 4,992,204. The patent discloses tagging a material with a luminophore that is cross-linked with at least one poly (oxy alkylene). The tagging compound has an absorbance within the range of about 300 nm to 400 nm. Heretofore, fluorescent materials have substantially been used for security measures. For example, U. S. Patent No. 4,504,084 issued to Miehe et al. on November 12, 1991 discloses a method for marking originals so that copies can be distinguished from the originals. The method includes using a ribbon having a printing medium for printing the original. The ribbon includes a substance in the foπn of a marking which, when used, produces an invisible distinguishable marking which is recognizable only by using a special scanner. U. S. Patent No. 4,540,595 discloses a water-based ink which provides markings that fluoresce when exposed to light in the near infrared wavelength. The water-based ink is used to mark documents such as bank checks for automatic identification. U.S. Patent No. 5,614,008 discloses a water-based ink containing a near infrared fluorophore. The formulated inks are useful in continuous or drop-on-demand, bubble-jet, and piezo-electric, impulse ink jet printers. U. S. Patent No. 5,083,814 issued to Guinta et al. on January 28, 1992 discloses a security method for applying a security marking to an automobile, boat and the like. The method involves a nationwide network of authorized dealers which are supplied with input and output devices such as computer, monitor and a hand-held marking device. Using specified locations data supplied from a central process unit, the dealer applies to the surface of the automobile a confidential and invisible registration code. U. S. Patent No. 4,736,425 issued to Jalon on April 5, 1988 discloses a two-step marking method for important documents, such as security papers, bank bills, checks, shares, stamps and the like to prevent forgery and to authenticate the document. In the first step of the marking process, one or more elements which form a chelate are deposited in or on the security paper. The elements are chosen so that the chelate is not formed until later. In the second step of the process, the chelate is formed by depositing on the paper the missing components to produce the synthesis of the chelate. The missing elements are added to the paper by means of an aqueous alcoholic deposition. Accordingly, it is possible to deposit the ligands in the first step and the metal ions in the second step, or vice-versa. The chelated compounds are formed with metals and rare-earth elements and are invisible under sunlight but are fluorescent when exposed to ultraviolet light rays. U. S. Patent No. 4,591 ,707 issued to Stenzel et al. on May 27, 1986 discloses the use of a hallmark on financial paper, such as bank notes, currency and the like. The hallmark is a coating on the exterior surface of the paper substrate applied by vacuum disposition techniques, such as evaporation or cathode sputtering, in the form of a pattern, stripes or figures. U.S. Patent Nos. 5,234,720; 5,372,739; and 5,677,058 disclose altering certain surface characteristics of various fibers by applying and heat-setting thin coatings to fiber surfaces. For example, certain coatings provide the fibers with enhanced softness while others impart hydrophilic or hydrophobic characteristics. It is known that various additives can be blended into polymers and thereafter spun into fibers of various orientations. However, certain additives, such as dyes, optical brighteners, etc., can be difficult to remove from the interior of a spinning machine after a production batch has been completed. For example, attempts to spin a fiber with a yellow dyestuff additive immediately after spinning a batch containing blue dyestuff can cause some portion of the second fiber to have an undesirable greenish cast because small amounts of the first polymer/pigment mixture remained in the spinning machine. Thus careful, time-consuming and/or costly cleaning procedures between spinning batches are important. Alternatively, spinning machines are dedicated to a single polymer/additive combination to control/reduce undesirable batch-to-batch variation. Accordingly, there is a need for a fiber to incorporate a marking compound that is substantially invisible to the unaided human eye in UV and visible light wavelengths. Such fibers can be used for security measures. Such fibers may further be utilized during manufacture to provide "on line" checks for various fibers, yams, or threads used during the manufacture of a garment or other article. SUMMARY OF THE INVENTION The present invention, defined in its broad embodiment, is a fiber, natural or synthetic, woven or nonwoven, having a near infrared fluorophore bound to the fiber by a cross-linking compound. The near infrared fluorescing compound has a wavelength absorbance greater than about 600 nm and produces a fluorescence having a wavelength greater than the absorbed wavelength. Another aspect of the invention is a method for marking a fiber with a near infrared fluorescing compound having an absorbance greater than about 600 nm. The method includes the step of contacting the fiber with a cross-linking compound and a fluorescing compound. The method can further include treating the fiber with a non- neutral preparation wash and drying the treated fiber before cross-linking compound contacts the fiber. The non-neutral preparation wash can include a caustic treatment followed by acid neutralization. Another aspect of the invention is a method for detecting a fluorescent marker and optionally identifying the article from the fluorescence. It is an object of the invention to provide a fiber having associated with at least a portion thereof a fluorescing compound substantially having an absorbance greater than 600 nm. It is another object of the invention to provide an article having a fiber incorporated therein where the fiber includes a fluorescing compound substantially having an absorbance greater than 600 nm. It is another object of the invention to provide a method for marking a material with a fluorescing compound. These and other objects and advantages of the present invention will become apparent to those skilled in the art from the following description of the preferred embodiment thereof. DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a variety of natural and man-made fibers may be readily marked with certain compounds by contacting the fiber with a marking compound of the present invention. In accordance with the present invention, the marking compound(s) is associated with the fiber using the aid of a cross-linking compound. Fibers useful in the present invention can be natural or synthetic and include wool, cotton, flax, jute, paper, fur, cardboard, polyesters, copolyesters, cellulose acetate, polyacrylic, nylon, olefms, viscose rayon, polyphenylene sulfide and mixtures thereof. The fibers can be used in the manufacture of various products, such as, woven cloth, nonwoven materials, paper products, cardboard, adhesive tapes and the like, in addition, suitable materials for marking can include those which are somewhat absorbent, have roughened or embossed surfaces or may be penetrated to some degree, such as certain rubber products; leather materials; foamed backings for nonwovens; textiles; fur; carpets; and other products. Preferably, the fibers have at least one continuous groove and can have round or non-round geometry cross-sections, such as those described in U.S. Patent Nos. 4,842,792, 4,954,398, 5,372,739 and 5,677,058, the entire disclosures of which are incorporated herein by reference. The surface of the groove is preferably rougher than the surface outside of the groove. The grooves can also be arranged in a circular pattern around a solid or hollow core. Desirably, the non-round fibers have at least 1 to about 30 grooves or channels which are substantially contiguous. Fibers having a plurality of grooves have a larger surface area per unit weight than round fibers and offer greater sites for associating the fluorescent compound with the fiber. A preferred fiber is a tow of continuous filaments having between about 10,000 to about 100,000 total denier. Tows having a greater total denier may also be used if desired. The tow can be processed through a tow feeder and collected in a baler to form bales which are convenient for shipment. The tow can be opened by jets or bloomed by opening rolls and thereafter used in various nonwoven products, filters, and the like. For staple fibers, the total denier, prior to forming a staple fiber, can be as small as 30,000. However, tows greater than about 2,000,000 are preferred. The tow can also be subjected to crimping. The crimped or non- crimped fiber can have a staple length of about 0.5 centimeters to about 15 centimeters and a denier per filament of about 0.7 to about 200. The various man-made fibers can be spun in a continuous filament yam which may be further treated with lubricants, heat- setting materials and the like. Suitable polyesters and copolyesters which may be used with the present invention include relatively oriented polyesters and polyesters modified for basic dyeability. The cellulose acetate fibers useful in the present invention are well known to those skilled in the fiber art and may be prepared by melt-spinning or conventional solvent- spinning means using acetone or a solvent. For example, U.S. Patent No. 5,505,888 discloses a process for preparing cellulose fibers, the entire disclosure of which is incorporated herein by reference. The polyester materials useful in the present invention are polyesters or copolyesters that are well known in the art and can be prepared using standard techniques known to those in the polyester art. Suitable synthetic fibers may also include pigments, such as blanc fixe, delusterants, such as titanium dioxide, and optical brighteners incorporated into the fibers using known techniques and in known amounts. The fibers of the present invention may have any shape. Fibers and blends of fibers having different shapes may be particularly preferred as they provide an increased selection of unique, detectable fibers. Cross-linking agents useful in the present invention include modified polyester agents, acrylic cross-linking agents, modified acrylic copolymer emulsions, silicone-based cross-linking compositions, such as those available from Wacker Silicones, Inc., epoxy compositions, cross-linking polyurethane emulsions, and mixtures thereof. The cross- linking agents can be utilized either alone or in combination with suitable with initiators. The concentration of the cross-linking agent used may vary from about 0.05 weight % to about 50.0 weight %, preferably from about 1.0 weight % to about 20.0 weight %, and more preferably from about 2.0 weight % to about 10 weight %, wherein the weight percents are based on the dried weight of the treated fiber or treated material. Drying and curing of these cross-linking agents containing a marker composition can be accomplished in any manner which is suitable for removing water and/or heat setting to cause cross-linking to occur. Some agents can be satisfactorily cross-linked at room temperature while others require elevated temperatures. For example, ECCO-REZ U21, available from Eastern Color and Chemical Co., is a water dispersible polyurethane emulsion having an adjusted pH ranging from about neutral to about 10, cross-links at room temperature, while ECCO-REZ M907, also available from Eastern Color, is a modified acrylic resin emulsion having a slightly acidic adjusted pH, cross-links at about 150°C. Marking compositions suitable for use in the present invention include a near infrared fluorophore such as those disclosed and described in U.S. Patents 5,461,136, 5,423,432, 5,461,136, and 5,614,008, the entire disclosures of each being incoφorated herein by reference. Typically, these fluorophore compositions have their major absorbance peak at wavelength above about 600 nm and preferably between about 650 nm and 1100 nm. However, compounds which fluoresce at wavelengths beyond the near infrared wavelength region may also be used, but are not preferred. Desirably, the fluorophores are invisible to the eye at the concentrations at which they are used, but still display sufficient fluorescence to allow accurate detection. The near-infrared fluorophores must also retain fluorescence after incoφoration into and/or onto a fiber and subsequent processing of the fiber into a fabric and the fabric into a finished article. Desirably, such compounds should be heat stable and resistant to ionic cleaning and processing steps commonly used in producing a garment. The preferred near infrared fluorescent compound are selected from phthalocyanines, naphthalocyanines and squaraines corresponding to formulae I, II and III: (II) (I) where Pc and Nc represent the phthalocyanine and naphthalocyanine moieties of Formulae la and Ila, Phthalocyanine 2,3-Naphthalocyanine la Ila respectively, covalently bonded to hydrogen or to various metals, halometals, organometallic groups, and oxymetals including AlCl, AlBr, AIOH, AIOR5, AISR5, Ge, Ge(OR 6 ), Ga, InCl, Mg, SiCl 2 , SiF 2 , SnCl 2 , Sn(OR 6 ) 2 , Si(SR 6 ) 2 , or Zn, wherein R 5 and R 6 are selected from hydrogen, alkyl, aryl, heteroaryl, lower alkanoyl, trifluoroacetyl, groups of the formulae: R, OR- R- OR, R- OR- I I I I I ! Sn — R, , Sn — OR„ , Si — R, , Si — OR, , Ge — R, , or Ge — OR, R, OR, R, OR, R, OR, R 7 , R 8 , and R 9 are independently selected from alkyl, phenyl or phenyl substituted with lower alkyl, lower alkoxy or halogen. X is selected from oxygen, sulfur, selenium, tellurium or a group of the formula N(R 1 o), wherein R 10 is hydrogen, cycloalkyl, alkyl, acyl, alkylsulfonyl, or arly or Rio and R taken together form an aliphatic or aromatic ring with the nitrogen atom to which they are attached. Y is selected from unsubstituted or substituted alkyl, alkenyl, alkynyl, C 3 0C 8 cycloalkyl, aryl, herteroaryl. R? OR, I I 7 alkylene- Si - R 8 or alkylene - Si - OR„ , I I R, 0* 9 (X-R) moiety is alkylsulfonylamino, arylsulfonylamino, or a group selected from the formulae -X(C 2 H 4 O) z R 1 , R, OR 7 R 7 OR 7 Sn — R R , Sn — OR fi , Si — R„ , or Si — OR- , R, OR, R 9 OR, wherein R 1 is hydrogen or R is as defined above; z is an integer from 1 to 4. Further, two (X-R) moieties can be taken together to form divalent substituents of the formula: X, / wherein each Xi is independently selected from -O-, -S-, or -N(R 10 )- and A is selected from ethylene; propylene; trimethylene; and such groups substituted with CpC 4 alkyl, C C 4 alkoxy, aryl and cycloalkyl; 1 ,2-phenylene and 1 ,2-phenylene containing 1-3 substituents selected from Cι-C alkyl, Cι-C 4 alkoxy or halogen. The Ri and R 2 moieties are independently selected from hydrogen, lower alkyl, lower alkoxy, halogen, aryloxy, lower alkyl-thio, arylthio, lower alkylsulfonyl; arylsulfonyl; lower alkyl-sulfonyl-amino, lower alkanoylamine, arylsulfonylamino, cycloalkyl-sulfonylamino, carboxy, unsubstituted and substituted carbamoyl and sulfamoyl, lower alkoxycarbonyl, hydroxy, lower alkanoyloxy, R, OR, R, OR, Sn — R x g 8 , Sn — OR s , Si — R s , or Si — OR R , R, OR, R, OR, The R 3 and R» moieties are independently selected from hydrogen, lower alkyl, alkenyl or aryl; n is an integer from 0-16; m is an integer from 0-24, provided the sums of n+m and nι+mι are 16 and 24, respectively. It is to be understood that when n, m, or mj . is 0, the respective moiety is absent. In a preferred embodiment of this aspect of the present invention, m is from 4 to 12; mi is from 0-8; provided that in the definitions of the substituents (Y)n, (Y)nι and (X-R)mι that these substituents are not present when n, , and mi are zero, respectively. Substituents (X-R) and (Y) are present in compounds la on there peripheral carbon atoms, i.e., in positions 1- 4, 8-1 1, 15-18, 22-25 and substituents (X-R) and (Y) are present on the peripheral carbon atoms of Ila, i.e., in positions 1 -5, 9-14, 18-23, 27-32 and 36. In the above definitions, the term alkyl is used to designate a straight or branched chained hydrocarbon radical containing 1-12 carbons. In the terms lower alkyl, lower alkoxy, lower alkyl—thio, lower alkoxycarbonyl, lower alkylsufonyl, lower alkylsufonylamino, lower alkanoylamino, lower alkanoyl and lower alkanoyloxy the alkyl portion of the groups contains 1-6 carbons and may contain a straight or branched chain. The term "cycloalkyl" is used to represent a cyclic aliphatic hydrocarbon radical containing 3-8 carbons, preferably 5 to 7 carbons. The alkyl and lower alkyl portions of the previously defined groups may contain as further substituents one or more groups selected from hydroxy, halogen, carboxy, cyano, Cj-C -alkoxy, aryl, Cι-C 4 -alkylthio, arylthio, aryloxy, Cι-C -alkoxycarbonyl or C]-C 4 -alkanoyloxy. The term "aryl" includes carbocyclic aromatic radicals containing 6-18 carbons, preferably phenyl and naphthyl, and such radicals substituted with one or more substituents selected from lower alkyl, lower alkoxy, halogen, lower alkylthio, N(lower alkyl)2, trifluro -methyl, carboxy, lower alkoxycarbonyl, hydroxy, lower alkanoyl-amino, lower alkylsulfonylamino, arylsulfonyl-amino, cycloalkylsulfonylamino, lower alkanoyloxy, cyano, phenyl, phenyl-thio and phenoxy. The term "heteroaryl" is used to represent mono or bicyclic hetero aromatic radicals containing at least one "hetero" atom selected from oxygen, sulfur and nitrogen or a combination thereof. Examples of suitable hetero-aryl groups include: thiazolyl, benzo- thiazolyl, pyrazolyl, pyrrolyl, thienyl, furyl, thia-diazolyl, oxadiazolyl, benzoxazolyl, benzimidazolyl, pyridyl, pyrimidinyl and triazolyl. These heteroaryl radicals may contain the same substituents listed above as possible substituents for the aryl radicals. The term triazolyl also includes structure IV and mixed isomers thereof, IV wherein Ri i is hydrogen or selected from lower alkyl and lower alkyl substituted with one or two groups selected from hydroxy, halogen, carboxy, lower alkoxy, aryl, cyano, cycloalkyl, lower alkanoyloxy or lower alkoxy-carbonyl. The terms "alkenyl and alkynyl" are used to denote aliphatic hydrocarbon moiety having 3-8 carbons and containing at least one carbon-carbon double bond and one carbon-carbon triple bond, respectively. The term halogen is used to include bromine, chlorine, fluorine and iodine. The term "substituted carbamoyl" is used to denote a radical having the formula - CONRι 2 Rι 3 , wherein Rι 2 and Rπ are selected from unsubstituted or substituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl. The term "substituted sulfamoyl" is used to denote a radical having the formula - SO2NR 12 Ri 3 , wherein Rι 2 and Rι 3 are as defined above. The term "alkylene" refers to a divalent Cι-Cι 2 aliphatic hydrocarbon moiety, either straight or branched-chain, and either unsubstituted or substituted with one or more groups selected from lower alkoxy, halogen, aryl, or aryloxy. The term "acyl" refers to a group of the formula R°C(O)-O-, wherein R° is preferably a Cj-Cio alkyl moiety. The term "alkyl sulfonyl" refers to a group of the formula R°SO2-, wherein R° is as defined for acyl. The concentration of the near infrared fluorophore making compound can vary from about 10 ppm to about 30 weight %. The preferred level of the fluorophore is from about 0.1 weight % to about 10 weight %, and more preferably from about 0.1 to about 3 weight %. The concentration is selected to give an adequate fluorescence for the detection inspection or other specific purpose. Other additives may also be added to the composition of the present invention, for example, plasticizers, colorants, antioxidants, stabilizers, UV absorbers, UV blocking agents, defoamers, lubricants, flame retardants, nucleating agents, antimicrobials, TiO 2 , rare earths, optical brighteners, wetting agents, and the like. Such additives may be admixed with the composition of the invention or applied to the fiber separately. In accordance with another aspect of the present invention, a process is provided for marking the article, such as manufactured items like blankets, jackets, coats, woven or knitted goods, nonwovens, materials having fur, paper, cardboard, and the like. For example, nonwoven insulation material (about 1/8 to 3/4 inch thick) having crimped or non-crimped polyester fiberfill, nylon fibers or webs, battings of various deniers per filament, etc. can be treated with a pattern of single drops or fine spray of a cross-linking/ marker composition of the invention followed by compression to distribute the drops more deeply into the material. Preferably, a moving porous screen or series of suitable hinged plates can carry the freshly treated material from the spray-application zone into and through a heating zone. In some cases, immediately following spraying, light contact with a fixed or moving felt strip, light brushes, jets of air, or vacuum could be used to remove excess cross-linking marker from the surface of target materials or be used for spreading or penetrating the marking composition on or into the treated material . Fiberfill battings and other materials can further be bonded with a typical over spray of an acrylic adhesive or other suitable agent to bond the fibers followed by curing in an oven either before or after application of the cross-linking/ marker composition. Such bonded fiberfill batting can also be over wrapped or sandwiched between suitable fabrics and held in place by a fixing means such as adhesive, sewing or otherwise to create an insulation material suitable for use in coats, jackets, blankets and the like. In many cases, one side of such material is covered by a light, thin, nonwoven scrim or woven fabric through which the marker can be detected with a suitable instrument. Another process for treating an article of manufacture includes the steps of: preparing the target material, using a vacuum-assisted application means for removing the excess cross-linking/marker composition from a surface of the target material, covering the marked material using a light web or fabric, and optionally, curing the cross- linking/marker composition in an appropriate manner. This marked material may then be used in the fabrication of a final product. The sequence of steps in the above procedure are not critical and can be changed as needed for a given product. In some cases only the intermediate of the article such as a fiber, cord, filament, web, tow or yarn (hereinafter collectively referred to as a fiber) is desired to be contacted with the cross-linking/marker composition of the invention. In treating the fiber, any suitable method for applying the cross-linking/marker composition is envisioned to be within the scope of the present invention. For example, application methods include: coated, rotating contact rolls which can be smooth or have designs embossed or attached to the surface thereof; automated and manually operated spray booths; immersion; sponge applications; felt-tip applications; printing devices and spraying systems used alone or in conjunction with templates to create a predetermined marker pattern on the targeted material. Such application can be followed by press rolls. It is also within the scope of the invention to use an air blower or vacuum apparatus to increase the penetration of the marker compositions into the fiber or material being treated. Desirably, the fiber is brought into contact with an aqueous solution which may contain a dissolved, colloidal, suspended or otherwise dispersed marking compound and cross-linking agent. In a preferred process of the present invention the fiber is treated with a non-neutral solution adequate to modify the fiber surface prior to contacting the fiber with the cross- linking/marker composition. Although not wishing to be bound by any theory, it is believed that the non-neutral solution facilitates the association of the cross-linking compound or the fluorescing compound and desirably both compounds with the fiber. The ability of certain cross-linking compounds and marker compositions to become substantially cross-linked or securely attached to the surface of the fiber could possibly relate to a combination of factors, such as, scarring or pitting the fiber surface or removal of interfering substances such as any processing lubricant, surface monomer, etc. The non-neutral solution can have a pH greater than 7 and include from about 0.01 weight percent to about 4 weight percent of caustic and/or triethanolamine, etc., and desirably from about 0.1 weight percent to about 2 weight percent of such additives. For certain cross-linking agents the non-neutral solution has a pH less than 7 and includes acetic acid, citric acid or both with a concentration of from about 0.01 weight percent to about 10 weight percent, and preferably from about 0.5 weight percent to about 4 weight percent. The fiber may also be treated using a combination of the above where the fiber is contacted with a solution having a pH greater than 7 which is subsequently neutralized, if needed, using an appropriate acidic solution having a pH less than 7 . This caustic/acid neutralization step can further include at least partially drying the fiber prior to acid neutralization. The drying step is preferably conducted at a temperature of at least about 120°C and more preferably at a temperature of at least about 145°C, for about 30 seconds to about 5 minutes. It is understood that the temperature should not be so high as to melt or degrade the fiber. In addition to the above acids, other suitable acids which may be used alone or in the neutralization step, include ascorbic as well as mixtures of acetic, citric, and ascorbic acids. The selection of treatment with non-neutral solutions can result in fibers which have a superior combination of important characteristics including processability, liquid transport, marker durability, and overall improved performance compared to other fibers not receiving such treatments. In a particularly preferred aspect of the present invention, fibers having a suitable non-round cross-section and longitudinal grooves are substantially continuously caustic- treated as described above. Advantageously, a significant amount of a cross-linking agent/marker composition is adhered to the fiber surface. The cross-linking agents provide a site for the association of the fluorescent compound with the fiber. Although not wishing to be bound by any theoiy, it is believed that fibers having 2 and less than about 30 longitudinal or axial grooves tend to hold the cross-linking agent and fluorescing compound in a superior manner. Another aspect of the invention relates to a method for detecting a material having a fluorescing compound associated with the material. The method includes the steps of subjecting the material to an excitation radiation having a wavelength greater than about 600 nm to produce a fluorescence having a wavelength greater than about 670 nm from the compound and detecting the fluorescence. The material has at least one and may have more than one fluorescing compound associated with the fibers of the material. When two or more fluorescing compounds are associated with the fiber, it is preferable for the fluorescing compounds to have separate and distinctly identifiable absorption bands. In accordance with the invention, the fluorescing compounds are associated with the fibers by one or more of the cross-linking compounds described herein. In detecting the presence of the fluorescing compound, the material is subjected to an excitation radiation having a wavelength at the absorption peak of the fluorescing compound. The fluorescence produced by the fluorescing compound is predominantly in the near-infrared region of the spectrum. The fluorescence is then detected using a suitable detector known to those skilled in the light-detection art. The detector can be fixed, hand-held, scanner, "yes-no" detectors, or a CCD camera and can include a compensation mechanism, such as filters or software or combinations thereof, to appropriately negate any light in the fluorescence spectra that would not be attributed to the fluorescing compound. The fluorescing compound can further be used to identify the material or an article made from the material. For example, the fluorescing compound associated with the fibers or yarn can be woven into the material to make a specific design or sewn at a specific location and used to identify the object or provide a means for authentication. The following examples are intended to further illustrate the invention and are not intended as a limitation thereof. COMPARATIVE EXAMPLE Approximately 50 milliliters (ml) of water and 25 ml of a modified polyester, cross- linking agent, (BAYPRET USV available from Bayer China Company Ltd.) were admixed together. About 0.1 gram of an optical bleach powder (UVITEX OB-3) was added to about 25 ml of the water/cross-linker mixture and stirred thoroughly. The polyester/optical bleach mixture was applied to a 30 cm length of lubricated cellulose acetate, 8 denier per filament, "Y" cross-section yarn (about 300 total denier) with the amount of add-on coating being somewhat variable. The yarn was then heat treated using an oven with air circulation for about 10 minutes at a temperature of about 135°C. The yarn did not receive any special preparation prior to the application. The coated heat-set filament yarn produced a fluorescent response in a dark enclosure equipped with a suitable ultraviolet source. The coated ya was dry weighed, placed in an open mesh bag, washed in a standard home washing machine using liquid detergent and fabric softener, dried and weighed again. The fluorescence of the sample was tested again after being washed and dried. The signal of the fluorescing marker was not as strong compared to the prewashed state. Thus, the coating conditions of this example are not acceptable for attaching markers to fibers in a manner which can survive multiple washings. EXAMPLE 1 Samples of the yam used in the Comparative Example above were treated using a solution having about 0.4 weight percent caustic in water. The ya was submerged in the solution for at least 5 seconds then subjected to steam treatment for at least 4 seconds. The residual caustic was neutralized using 0.5 weight percent acetic acid. The yarn was then washed in hot water and at least partially dried. To control static, the yam was lightly lubricated using about 0.3 weight percent of a hydrophilic lubricant described in U.S. Patent 5,372,739, Example 10, the entire disclosure of which is incorporated herein by reference. The treated yarn was then wound onto a paper tube. Several cords of about 15 centimeters (cm) in length were cut from the tube, thoroughly washed using hot tap water at about 50°C and dried. The cords were treated with the cross-linking agent/optical bleach mixture of the Comparative Example above and heat-treated as described above. The yam produced a strong fluorescent response in the detection enclosure before and after 1 washing and drying cycle. The fluorescent compound appeared to be more firmly associated with the fiber relative to the Comparative Example. EXAMPLE 2 About 500 meters of a 2-ply polyester multi-filament cord having a round cross- section and a total denier of about 2165 were subjected to a caustic washing treatment using a 2 weight percent solution at a temperature of about 70°C to 75°C. The fiber was heated for under 10 seconds in a steam chest using 6 psig steam then acid neutralized using 0.5 weight percent acetic acid. The fiber was then dried using heated rolls. The following components were combined and stirred to a unifoπn mixture: 1) 8 ml of a 30 weight percent marker dispersion composition having a 780 nm fluorescence described in U.S. Patent No. 5,614,008, Example 6; 2) 8 ml of a 30 weight percent marker dispersion composition described in U.S. Patent No. 5,614,008, Example 10 having a concentration of about 1000 ppm and a 670 nm fluorescence; 3) 150 ml of the hydrophilic polyester cross-linking resin Repel-O-Tex PSR 200, available from Rhone-Poulenc Corp.; and 4) 150 ml of Millipore water. The cross-linking/marker admixture was applied to the dried filament cord using a rotating kiss-roll application system. The cross-linking/marker admixture was maintained at a pH between about 4 and 9 using acetic and triethanolamine, as required. The cord was collected wet on a paper tube. The treated cord was heat-cured to trigger cross- linking action by subjecting the cord to a temperature of about 150°C for about 5 to 7 minutes using an air- circulated oven. After application and drying, the fiber had a total denier of about 2464, representing a gain of about 13.8 percent. A small skein of treated cord weighing 1.09 grams was inserted into an open-mesh bag designed for washing sweaters, delicate clothing and the like and washed using water having a temperature of about 50°C. Liquid laundry detergent and softener were added to the wash and rinse water, respectively. The washed cord was dried and weighed. It was found that the skein had lost about 5.5 percent of its original as-treated weight. The fluorescent markers were still detectable using an appropriate instrument as described in U.S. Patent No. 5,423,432 after 1 washing and drying cycle using permanent-press conditions. However, there was a reduction in fluorescence after the second washing and drying treatment. EXAMPLE 3 Lubricated crimped polyester fibers having an 8-groove cross-section, 6 denier per fiber and a two- inch staple length were used to produce a 4.0/1 cotton-count yam. The yam was caustic-treated and acid washed to remove the lubricant, coated with the marker admixture and dried as described above in Example 2. The marked fiber was subjected to 2 washing and drying cycles, using permanent-press conditions. The fiber had a weight loss of only about 0.9 percent. The fluorescent markers were readily detected before and after both washing and drying treatments. EXAMPLE 4 Cellulose acetate was used in a solvent-spinning system to produce an 8 denier per filament, "Y" cross-section, continuous, multi-filament yam having a total denier of about 300. The yarn was thoroughly cleaned using a solution having about 0.4 weight percent caustic. After 24 hours the caustic was neutralized using about 0.5 weight percent acetic acid at a temperature of about 76°C. The fiber was then dried as described above. The marking composition below was admixed and applied to the dried yam using a rotating kiss-roll application system. 1) 12 ml of a 30 weight percent marker dispersion composition of Example 2 having a 780 nm fluorescence; 2) 12 ml of a 30 weight percent marker dispersion composition of Example 2 having a 670 nm fluorescence; 3) 150 ml of the hydrophilic polyester cross-linking resin Repel-O-Tex PSR 200; and 4) 250 ml of distilled water. The yam was collected wet on a paper tube. The treated yam was thoroughly dried and heat cured at about 145°C. It was determined that, after drying and curing, about 3 weight percent of the cross-linking/marker composition had been applied. A sample of the treated filament yam was wound by hand onto a skein about 3 cm in diameter. The skein weighed 0.699 grams. The skein was washed in a household washing machine and dried as described above in Example 2 . After 1 washing and drying cycle, the marker was still readily detectable. After 4 permanent-press washing and drying cycles, the skein had lost about 3.7 weight percent. Detection of the markers on the yam had become variable with little or no signal detected on some portions of the skein and a satisfactory signal on other portions. EXAMPLE 5 A polyester sewing thread having a total denier of about 170 was subjected to a caustic/acid neutralization treatment as described in Example 2. The thread was coated with an admixture having about 300 ml of an acrylic cross-linking agent (ROHM 841 16 available from Rohm and Haas), about 3.5 ml of the optical bleach brightener (UVITEX OB-3) and about 4.5 ml of the Naphthalocyanine marker dispersion composition described in U.S. Patent No. 5,614,008, Example 6 (1000 ppm concentration). The coated thread was dried and heat-set at about 135-140°C for about 12 minutes. The thread was wound onto a 0.8 gram skein. The dried coating added about 3 to 5 weight percent to the fiber weight. A positive response was obtained in both the ultraviolet and near-infrared wavelengths before and after one washing and drying treatment using permanent-press setting. These results indicate that cross-linking/ marker compositions in both wavelengths as described can be attached to various fibers and/or other materials with reasonable durability. EXAMPLE 6 A 2-ply, 100 percent cotton yam, Winton brand Type 1579, having a total denier of about 300, made in Gastonia, NC, USA, was treated using about 0.3 weight percent acetic acid washing bath having a temperature of about 76°C. The yam was subjected to the acetic acid bath for at least about 4 to 10 seconds using suitable submerged guides. Downstream stripper guides (outside the bath) and a liquid-removal jet completed the acid washing and partial liquid-stripping treatments. The same cross-linking/marker composition and heat-curing treatment described in Example 2 were used for this cotton yam. The yam had a weight increase of about 3 to 5 percent after diying. Several skeins of about 1 gram each were prepared as previously described. After 5 washing and diying cycles using household laundry equipment, the skeins had a loss of about 2.6 to 2.8 weight percent. The markers were readily detected with no major variation in detection around the skein. The use of an acid wash is beneficial as a preparatory procedure for obtaining long- lasting attachment of compositions consisting of a combination of a cross-linking agent and an identification marker as described. A higher temperature for the acid wash or a different acid solution may be used depending upon the pH required for the cross-linking agent. EXAMPLE 7 The following yams were acid washed as described in Example 6 above: 1) 6 denier/filament, polyester staple fibers having grooved cross-sections spun into a 4.0/1 cotton-count yam; 2) 100 percent mercerized cotton yarn (20/1 cotton count); and 3) 60/40 mercerized cotton/polyester blend yam (30/1 cotton count, ring-spun). These yams were treated and cured using the cross-linking/marker composition and procedure described in Example 2. Strong cross-linked attachment was confirmed by multiple washing and detection tests. For most applications, acetic acid or citric acid mixtures in water having about 0.2 weight percent to about 5.0 weight percent acid are preferred for hot washing, especially when a suitable hydrophilic lubricant as previously described is used on the fibers prior to hot washing. This combination provides a preparatory procedure which produces suitably cleaned and pH-adjusted surfaces onto which the cross-linking marker compositions can be applied and cured. EXAMPLE 8 A 6.5 ounce per square yard nonwoven batting of fiberfill (about 0.75 inch thick) was treated with single drops of the cross-linking marker described below with about 2 inches between drops followed by compression to increase penetration into the batting. The marker consisted of the following components which were stirred well during addition: 1) 50 ml of ECCO-REZ U21 of the cross-linking agent as received from Eastern Color and Chemical Co. 2) 9 ml of triethanolamine to adjust the pH to about 8.5 3) 600 ml of Millipore water 4) 50 ml of a 30 weight percent marker dispersion having a 670 nm fluorescence of Example 2. Each drop of the above mixture weighed about 0.038 grams. ECCO-REZ U21 is a water-dispersible polyurethane emulsion which is capable of air-drying at about room temperature to achieve a cross-linked state. The treated batting was covered on both sides with a thin, translucent, nonwoven web weighing about 1 ounce per square yard. The air- dried material was wound into a roll for later use as an insulation fabric in jackets, coats, etc. It was observed that this compression treatment caused reduction in thickness of about 0.2 of an inch and an increase in density in the air-dried material. If desired, a reduction in thickness of the nonwoven batting can also be achieved by needle-punching and/or stitch-bonding. A sample of about 12 12 square inches was cut from the roll. The drops of cross- linking marker were readily detected using a "Wizard V6" viewer made by V. L. Engineering, Inc. of Cincinnati, Ohio. EXAMPLE 9 In some cases a loss of thickness is not desirable for the final marked, bonded, fiberfill product, such as described in Example 8. In an effort to minimize such thickness loss while obtaining increased penetration of the cross-linking/marker composition, the batting was placed in contact with a vacuum. In this case, the batting was placed in an essentially vertical position against a vacuum means having a width greater than the width of the batting. A small hand-held pump spray (2 fluid ounce capacity) was used. At 3 inches from a target, the droplet spray pattern had a diameter of about 2 inches and at a distance of 8 inches, the diameter increased to about 5 to 6 inches with rather ragged edges. Different spraying nozzles and masks or screens can be used to create different droplet sizes and/or various patterns of cross-linking marker on the target material. Also the cross-linking agent without a marker composition can be applied to the fiber before or after the cross-linking/marker composition is applied to create relatively uniform texture in a given target material when needed. The vacuum was sufficient to pull about 2 to 3 diy weight percent of a fine spray of cross-linking/marker composition into the material. After air-drying, it was found that the batting had lost very little thickness, in this case only about 1/16 inch from the original approximately 3/4 inch. EXAMPLE 10 Using the cross-linking/marker composition and fiberfill batting material of Example 8, different spraying techniques and patterns were used. The fiberfill batting was subjected to a pattern of single sprays of about 2 Vi inches in diameter and spaced about 6 inches apart in length and width. Using a spray-containment booth, spraying was done immediately before the porous scrim was placed on the batting. Each spray added approximately 0.035 grams of the cross-linking/marker composition to the batting. The amount added was determined by subjecting an 8 Vi inches x 11 inches sheet of paper ("Springhill Incentive DP," No. 13145) to a single spray lasting about Vi second from the small hand-held spray pump device used in Example 9. The cross-linking/marker composition was readily detected using the Wizard V-6 instrument of Example 8. Four samples of about 12 inches X 12 inches of the nonwoven fiberfill batting described in Example 8 were sprayed on one side with approximately 0.75 to about 1.5 ounces per square yard of the following cross-linking/marker formulation: 1) 8 ml of the 670 nm marker; 2) 112 ml of "ECCO-REZ U21 " cross-linking agent; 3) 112 ml of distilled water; and 4) sufficient triethanolamine to adjust the pH of the mixture from about 8 to about 8.5. Spraying was done with the batting supported on a porous metal screen equipped with a low-velocity, air-suction fan to assist in pulling the droplets onto the batting surface. The porous scrim was placed onto the freshly sprayed surface with sufficient pressure to assure good contact. The material was dried, with air circulation, at a temperature of about 65 to 75°C for about 5 minutes. The batting remained at room temperature undisturbed for about 8 hours. It was found that the scrim had become lightly bonded to the batting. The cross-linking/marker composition was readily detected using the Wizard V-6 instrument described above. Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting to the invention described herein. No doubt that after reading the disclosure, various alterations and modifications will become apparent to those skilled in the art to which the invention pertains. It is intended that the appended claims be interpreted as covering all such alterations and modifications as fall within the spirit and scope of the invention. For example, a series of cross-linking /fluorescing compositions which have specific wavelength absorbency and which may further exhibit selective affinity for particular types of materials, fabrics, fibers, yams, or compound compatibility can be used to treat the fiber or other material. It will further be appreciated that manufacturers choose different types and/or blends of fibers to obtain various performance characteristics, such as high strength, filtration performance, hydrophobic or hydrophilic characteristics, wrinkle resistance, drape, warmth, and many others. These fibers are acrylic, cellulose acetate, cotton, nylon, polyester, silk, viscose rayon, wool wood pulpand/or blends of such fibers. In applications in which liquid-transport is important, fibers with grooved cross-sections, such as "figures'', "8-groove", "Y", "rounded delta", "H", "flared H", trilobial, etc. in different deniers per filament as required for various needs ranging from distinctive appearance to physical properties may also be used in accordance with the invention.

Claims: CLAIMS We claim: 1. A composition comprising: a) a fiber; b) a fluorescing compound having an absorbance greater than about 600 nm; and c) a cross-linking compound associated with said fiber and linking said fluorescing compound to said fiber. 2. The composition of claim 1 wherein said fiber comprises a natural material. 3. The composition of claim 2 wherein said natural material is selected from the group consisting of wool, cotton, flax, jute, paper, fur, cardboard and mixtures thereof. 4. The composition of claim 1 wherein said fiber comprises a synthetic material. 5. The composition of claim 4 wherein said synthetic material is selected from the group consisting of polyesters, copolyesters, cellulose acetate, polyacrylic, nylon, olefms, viscose rayon, polyphenylene sulfide and mixtures thereof. 6. The composition of claim 5 wherein said polyester is selected from the group consisting of oriented and substantially nonoriented polyesters and including starch, modified starch, cellulose acetate, cellulose propionate, cellulose butyrate and starch acetate. 7. The composition of claim 5 wherein said cellulose acetate fibers are prepared by melt-spinning. 8. The composition of claim 5 wherein said cellulose acetate fibers are prepared by solvent-spinning. 9. The composition of claim 1 further comprising at least one other material selected from the group consisting of pigment, delusterant, rare-earth material, antimicrobial, UV blocking agent, UV absorber, defoamer, surfactant, wetting agent, optical brightener and mixtures thereof. 10. The composition of claim 1 wherein said near infrared fluorescing compound is selected from the group consisting of phthalocyanines, 2,3-naphthalocyanines and squaraines corresponding to Formulae I, II and II described herein. 11. The composition of claim 1 wherein said cross-linking compound is selected from the group consisting of a polyester agent, acrylic cross-linking agent, modified acrylic copolymer emulsion, silicone-based cross-linking materials, epoxy compositions, cross-linking polyurethane emulsions and mixtures thereof. 12. A fiber having a fluorescence when exposed to an illumination light source having a wavelength ranging from about 650 nm to about 1 100 nm, comprising the fluorescing compound of claim 10 and a cross-linking compound associated with said fiber and linking said fluorescing compound to said fiber. 13. The fiber of claim 12 selected from the group consisting of wool, cotton, fur, flax, jute, paper, cardboard, polyesters, copolyesters, cellulose acetate, polyacrylic, nylon, olefms, viscose rayon, polyphenylene sulfide and mixtures thereof. 14. The composition of claim 12 wherein said cross-linking compound is selected from the group consisting of a polyester agent, acrylic cross-linking agent, modified acrylic copolymer emulsion, silicone-based cross-linking materials, epoxy compositions, cross-linking polyurethane emulsions and mixtures thereof. 15. The fiber of claim 13 wherein said fiber is incorporated into an article of manufacture selected from the group consists of paper, fur, textiles, leather, polymeric films, adhesive tapes, nonwoven sheets and mixtures thereof. 16. A method of marking a material with a fluorescing compound comprising contacting the material with a cross-linking agent and a near-infrared fluorescing compound, said fluorescing compound having an absorbance of illumination radiation ranging from about 650 nm to about 1 100 nm. 17. The method of claim 16 wherein said fluorescing compound and said cross- linking agent are mixed together to form a mixture and said cross-linking agent has a concentration after drying and curing of about 0.5 to about 50 weight percent, based on the weight of the fiber or other material. 18. The method of claim 17 wherein said cross-linking agent has a concentration after drying and curing of about 1.0 to about 20 weight percent, based on the weight of the fiber or other material. 19. The method of claim 17 wherein said cross-linking agent has a concentration after drying and curing of about 2.0 to about 10 weight percent, based on the weight of the fiber or other material. 20. The method of claim 16 further comprising contacting said material with a non-neutral pH solution prior to contacting said material with said cross-linking compound. 21. The method of claim 20 wherein said solution has from about 0.01 to about 10 weight percent of an acid selected from acetic, citric and combinations thereof. 22. The method of claim 20 wherein said solution has from about 0.1 to about 4 weight percent of caustic. 23. The method of claim 16 further comprising treating said material with a caustic/acid neutralization step, wherein said treating step includes caustic-treating the material, heating the material and substantially neutralizing excess caustic using an acidic solution. 24. A method for detecting a material having a fluorescing compound associated with the material, said method comprising the steps of subjecting said material to an excitation irradiation having a wavelength greater than about 600 nm to produce a fluorescence having a wavelength greater than about 700 nm from said compound and detecting said fluorescence. 25. The method of claim 24 further comprising the step of identifying said material in response to said fluorescence. 26. The method of claim 25 wherein at least two fluorescing compounds are associated with said material. 27. The method of claim 26 wherein said at least two fluorescing compounds absorb said excitation radiation at distinctly different wavelengths.

Inventors: CUSHMAN MICHAEL ROY, KRUTAK JAMES JOHN SR, NEAL RICHARD DIXON, CUSHMAN, MICHAEL, ROY, KRUTAK, JAMES, JOHN, SR., NEAL, RICHARD, DIXON
Applicants: EASTMAN CHEM CO, EASTMAN CHEMICAL COMPANY
Application year: 1999
Main classification: D06P1
IPC codes: C09J7, D06H1, D06P1