Patent Publication Number: US-2004053047-A1

Title: Colorable filaments from polymer blend

Description:
BACKGROUND OF INVENTION  
       TECHNICAL FIELD  
       [0001] The present invention relates, in general, to synthetic polymer filament, such as nylon filament, for instance, nylon filament used in making the tuft portion of carpet. More particularly, the present invention relates to synthetic polymeric filament that is made from a polymer blend, such as a blend of both virgin nylon and recycle nylon, where the filament made from the blend will accept colorant as well as filament made from 100% virgin polymer.  
                               ABBREVIATIONS                                                bulked continuous filament   BCF           cubic feet per hour   cfh           deciliter   dL           gram   gm           milliequivalent   meq           milliliter   mL           Nylon Polymer and Plastics, a division of Solutia, Inc.   NPP           parts per million   ppm           polybutylene terephthalate   PBT           polyester   PE           polyethylene terephthalate   PET           polytrimethylene terephthlate   PTT           polypropylene   PP           solution dyed nylon   SDN           styrene-butadiene rubber   SBR           sulfonated lithium isophthalic acid   SLIA           sulfonated sodium isophthalic acid   SSIA                      
 
       [0002] Typically, carpet has a face fiber (the tuft portion) that is adhered to a backing material. The face fiber may be a synthetic polymer, for instance polyamide, i.e., nylon (such as nylon 6 and/or nylon 6,6), polyester (such as PET or PTT), and/or polypropylene, and/or the face fiber may be a natural material such as wool. Usually the face fiber contains dye, soil repellent, and/or stabilizer. Carpet fiber should accept dyes or pigments, so that the end consumer can choose a color of carpet as desired. The backing material may be a mat or fabric made of jute, polypropylene, or other material, typically with latex (such as SBR) in order to bind the face fiber and also may include a variety of inorganics such as calcium carbonate, clay, and/or hydrated alumina fillers.  
       [0003] In particular, fibers of nylon polymers have been used extensively as synthetic face fibers in carpets since the chemical and mechanical properties of polyamides make them suitable for such uses. The especially well suited and the most extensively used polyamides for carpets are nylon 6 (caprolactam polymer) and nylon 6,6 (polymeric reaction product of adipic acid and hexamethylene diamine). In fact, fibers of nylon 6 and fibers of nylon 6,6 account for about 55% of face fibers used in carpets in the United States. The other face fibers, PE fibers and PP fibers, used in carpets in the United States respectively account for about 5 to 10% and about 30%. The total of all other face fibers used in carpets account for less than about 5% in the United States.  
       [0004] More particularly, nylon fiber made from virgin nylon 6 polymer accepts dye well, and so does nylon fiber made from virgin nylon 6,6 polymer. Unlike most PET fiber, nylon fiber is dyeable not only at standard atmospheric pressure, which reduces the cost of dye vessels, but also is dyeable without harsh chemical carriers, which simplifies dyehouse processing. Thus, these attributes are significant factors, accounting for why the carpet industry uses about 55% nylon as the face fiber.  
       [0005] Both nylon 6 and nylon 6,6 have polymer chains terminating in carboxyl ends and in amine ends. The amine ends function as dye sites, and thus, nylon 6 fibers and nylon 6,6 fibers are dyeable using acid dyes. Nylon polymers may have additives to modify polymerization or to affect visual or tactile aesthetics. For instance, nylon may be complexed with a sulfonated compound such as, for example, sulfonated lithium isophthalic acid or sulfonated sodium isophthalic acid, so that the nylon fiber is dyeable with cationic dyes.  
       [0006] Of note, sulfonated nylon containing greater than about 4% by weight of an aromatic sulfonate or an alkali metal salt thereof, such as a lithium salt thereof, for making stain resistant nylon fiber is discussed in U.S. Pat. No. 5,889,138 issued Mar. 30, 1999 to Summers, assignor to Solutia, Inc. Non-sulfonated nylon fiber may have a stain blocking chemical topically applied in an aqueous bath after the nylon fiber has been dyed.  
       [0007] Dyeing of nylon fiber with acid dye and/or cationic dye is well known to those skilled in the art of making carpet. It is also well known that acid-dyeable nylon fibers of different amine levels will reach different color depths if all the different fibers are dyed together.  
       [0008] On the other hand, carpet with polyester as the face fiber is dyed in a manner different from the dyeing of nylon. More specifically, polyester fiber typically is beck dyed in a batch process with disperse dyes, which are powders or particulates that form a dye dispersion when placed in water. Disperse dyes are used for dyeing polyester fiber since polyester has no dye sites like the amine ends that are dye sites in nylon.  
       [0009] The energy needed to place the disperse dye into polyester fiber is available in both chemicals and heated pressure vessels. Typically, the chemicals are phenolic based compounds, and the dyeing is accomplished at atmospheric pressure with heat. On the other hand, the heated pressure vessel, which is called a jet beck, usually does not require phenolics due to the pressure. The dyeing process swells portions of the polyester molecular chain, resulting in the disperse dye being physically placed into the fiber. At the end of the dyeing cycle, the dye bath is cooled and the dye is entrapped into the fiber structure.  
       [0010] Some modified polyesters, which are called carrierless, do not require phenolic based compounds as carriers in order for the fiber to be dyed, and therefore are subject to the same types of dyes as the other polyesters but can be dyed via either a batch process (i.e., a beck process) or a continuous process.  
       [0011] Polypropylene is used as a face fiber in most low-cost Berber-style loop-pile carpet. PP carpet fiber is colored by being pigmented. The market share of PP carpet fiber is large, but seems to be in decline because PP functions well primarily in densely constructed loop pile, and Berber style is falling out of vogue.  
       [0012] During the last few decades, more and more effort has gone toward environmentally responsible methods of manufacturing, including finding ways to use waste products from the manufacture of various synthetic materials (post-industrial waste), where the manufacturers would otherwise dispose of the waste. Also, ways have been sought to use post-consumer waste from synthetic products. Thus, an important effort has been the development of ways for collecting and recycling the waste so it is re-used in other products.  
       [0013] Of note, emerging United States government standards call for &gt;50% recycle content in selected carpet installations in order to ameliorate carpet waste going to landfills. Thus, various attempts have been made in the carpet industry to employ recycled waste material in the manufacture of carpet.  
       [0014] For instance, sheath-core technology has been used by the carpet industry in order to employ recycled waste polymer in carpet fiber. In sheath-core technology, bi-component fibers are extruded with a virgin polymer for the sheath, and a recycled waste polymer for the core. The sheath polymer helps to mask undesirable characteristics that the core has due to the core being composed of recycled waste polymer.  
       [0015] More specifically, U.S. Pat. No. 5,885,705 (Parent), U.S. Pat. No. 6,004,674 (Divisional), and U.S. Pat. No. 6,039,903 (Divisional), all to Kent et al., assignors to BASF Corporation, describe sheath-core technology to make bi-component fibers for use in carpets. The fibers have an uncontaminated nylon 6 sheath and a contaminated core composed of nylon 6 derived from colored regenerated post-consumer nylon carpet fibers and/or composed of the cyclic dimer of caprolactam. The sheath may be pigmented.  
       [0016] Also, sheath-core technology is disclosed in U.S. Pat. No. 5,549,957 and U.S. Pat. No. 5,958,548, both to Negola et al., assignors to Nyltec Inc. These patents describe bi-component fibers having a virgin nylon 6 sheath and a core of PET, which has been recovered from beverage bottles (i.e., post-consumer waste), for use in carpets. The sheath may be dyed.  
       [0017] Another patent describing post-consumer waste PET, which has been recovered from beverage bottles for use in carpets, is U.S. Pat. No. 5,276,083 to Kawauchi, assignor to Kabuskiki Kaisha Shinkasho. This patent describes mixing recovered PET with a carbonic ester and pyrolyzing the mixture, followed by cooling to make regenerated PET, which can be employed for dyed fibers in carpets.  
       [0018] Of background interest with regard to polyester is U.S. Pat. No. 6,423,789 to Hayes, assignor to DuPont, which describes copolymerizing a preformed polyester having an inherent viscosity of at least 0.4 dL/gm, for instance PET, together with a poly(alkylene ether) glycol, for instance polyethylene glycol.  
       [0019] Also of background interest, but with regard to nylon, is U.S. Pat. No. 5,889,142 to Mohajer et al., assignors to Allied Signal. This patent describes chopping up used carpet and mixing the chopped resultant with a hot composition of caprolactam and water in order to dissolve and to recover nylon 6 from a carpet or nylon 6,6 from a carpet. A temperature of 120 180° Centigrade is used for recovery of nylon 6 and a temperature of 180 240° Centigrade is used for recovery of nylon 6,6.  
       [0020] Of general background interest are U.S. Pat. No. 5,294,384 (Parent) and U.S. Pat. No. 5,591,802 (Continuation), both to David et al., assignors to Monsanto. These patents describe chopping up used carpet (i.e., post-consumer waste of nylon tufts+polyolefin+SBR adhesive), running the chopped resultant through an extruder, and cutting the extrudate into pellets.  
       [0021] Also of general background interest is U.S. Published patent application Ser. No. 2001/0018118 A1 to Muzzy et al., which describes a matrix of recycled thermoplastic that may come from carpet (i.e., polyethylene, polypropylene, nylon, PET, or SBR) and high modulus fibers (i.e., glass, natural, carbon, or aramid).  
       [0022] The disclosures of all patents and published patent applications mentioned here are incorporated by reference.  
       [0023] Nevertheless, a need still exists for improvements where fibers to be used for textiles, such carpeting, should accept dye or pigment well when recycle polymer is included in the fiber.  
       SUMMARY OF INVENTION  
       [0024] Accordingly, the present invention provides a process for making colorable filament comprising blending virgin polymer A and recycle polymer A to form a mixture and forming the mixture into colorable mono-component filament that has a good colorability characteristic comparable to that of colorable mono-component filament formed from the virgin polymer A free of the recycle polymer A. Forming the mixture into colorable mono-component filament may comprise a first step of making the filament and a second step of coloring the filament, such as by dyeing the filament. Also, forming the mixture into colorable mono-component filament may comprise adding pigment into the mixture when making the filament.  
       [0025] Also, the present invention provides a colorable mono-component filament comprising virgin polymer A and recycle polymer A, and having a good colorability characteristic comparable to that of colorable mono-component filament made from the virgin polymer A free of the recycle polymer A. The colorable mono-component filament of virgin polymer A and recycle polymer A may be colored with pigment or dye by essentially the same procedures as are used for filament of virgin polymer A free of recycle polymer A, those coloring techniques including, but not limited to, pigment injection in the melt prior to filament extrusion, and to dyeing extruded filament via skein, space, beck, continuous, and print dyeing, all methods being familiar to those of ordinary skill in the art. The dye may be acid dye, cationic dye, space dye, or disperse dye.  
       [0026] Other features, aspects, and advantages of the present invention will become better understood with reference to the following description, accompanying Laboratory Examples, and appended claims.  
       DETAILED DESCRIPTION  
       [0027] The term “filament” as used here is meant to refer to the resultant elongated structure from polymers that are capable of being formed into a filament structure, typically having an elongated length at least about 100 times the width, and capable of being oriented (i.e., stretched or drawn) without breakage at least about 10%. The term fiber as used here is meant to refer to a group of filaments forming a threadline. The fiber structure may be in continuous filament form or the fiber structure may be in staple filament form, either of which form may be spun, knitted, woven, pressed, or otherwise formed into a textile. The fibers in accordance with the present invention, when used for face fiber in carpet, may be spun using conventional fiber-forming equipment known to those of ordinary skill in the art.  
       [0028] The term “mono-component” as used here in relation to fiber and/or filaments is intended to mean that the filaments forming the fiber are free of multiple polymeric layers, such as the two polymeric layers in the sheath-core fibers (also called bi-component fibers) disclosed in the above-discussed U.S. Pat. Nos. 5,885,705, 6,004,674, 6,039,903, 5,549,957 and 5,958,548. However, by the term “mono-component”, it is not intended to exclude one or more components in a bi-component or multi-component filament where the outer sheath of the filament is a polymer but the inner core of the filament contains carbon (which is not a polymer), typically the inner core being about ⅓ carbon and about ⅔ PE or PP. A major use of such bi-component filaments having a core that contains carbon is as a constituent in carpet tuft in order to provide antistatic characteristics to the carpet.  
       [0029] The phrase “bulked continuous filament” (abbreviated here as “BCF”) as used here is intended to refer to a carpet fiber made up of a bundle of filaments, typically about 60 to about 80, where the individual filaments have crimps or curls (i.e., bulked, appearing like when a person&#39;s hair is teased) and are unbroken for the full length of the yarn (i.e., continuous).  
       [0030] The term “textile” as used here is meant to refer to any spun, knitted, woven, pressed, non-woven, or otherwise formed material made from fiber, including fabric, cloth, velour, velvet, velveteen, corduroy, rugs, carpet, and the like, for which coloring with a colorant (including, but not limited, to dyeing in a bath, pigmenting, printing, patterning, space-dyeing, film lay-down, or disperse dyeing) is desired.  
       [0031] The term “colorant” as used here refers to any natural or synthetic compound or mixture of compounds (including, but not limited to, dyes or pigments) used to color or to dye the fibers of a textile in order to achieve a desired visual effect. The “coloring” process is intended to include, but not be limited to, traditional coloring processes with a dye bath, as well as coloring processes by pigmenting, printing, patterning, space-dyeing, film lay-down, disperse dyeing, and the like, as described here. For instance, during pigmenting, a colorant is admixed with the polymer flake, pellets, chips, or the like, and the resultant admixture extruded into fiber.  
       [0032] The term “colorability” as used here is the ability of fiber or filament to be fixed with a colorant, i.e., to accept a colorant. The phrase “characteristic of good colorability” as used here in relation to a colorable fiber or filament is intended to mean that the fiber or filament will accept colorant well, and thus, the colored fiber or filament should have a desired visual effect, for instance, should be acceptably uniform for commercial use.  
       [0033] The term “polymer” as used here generally includes, but is not limited to, homopolymers, copolymers (such as block, graft, random and alternating copolymers), terpolymers, et cetera, and blends and modifications thereof. Furthermore, the term “polymer” shall include all possible structures of the materials. These structures include, but are not limited to, isotactic, syndiotactic, and random symmetries.  
       [0034] The term “recycle” as used here in relation to a polymer in connection with the present invention is intended preferably to refer to post-industrial waste synthetic polymeric product that is leftover during the manufacture (i.e., extrusion, molding, and the like) of a polymeric product from virgin polymer (i.e., flakes, chips, pellets, and the like). For instance, when nylon is spun into yarn, there is leftover fiberstock that is off-specification yarn that would be thrown away instead of being sold to the customers of the yarn, and such leftover fiberstock that has been subjected to grinding, chopping, and the like to form flakes, chips, pellets, and the like, is an example of post-industrial waste that is recycle polymer in relation to the present invention as defined here. Also, the term “recycle” as used here in relation to a polymer in connection with the present invention may refer to post-consumer waste synthetic polymeric product.  
       [0035] The phrases “a blend of virgin polymer A and recycle polymer A”, “a mixture of virgin polymer A and recycle polymer A”, and the like, as used here are intended to refer to both of the polymers being the same kind of polymer generic class, except that one is virgin and one is recycle. For instance, both are nylon, both are polyester, and the like. Also, in the event that both of the virgin polymer and the recycle polymer are nylon, the two polymers may have different levels of amine ends, or different levels of sulfur from being complexed with a sulfonated compound.  
       [0036] Nylon polymers (i.e., polyamides) may be advantageously employed in the present invention. By nylon polymer, it is intended to include copolymers and terpolymers thereof. Suitable nylon polymers are nylons which can be produced as polymers of the reaction products of (i.e., polycondensation products and/or polyaddition products of) various combinations of diacids and diamines or lactams, as well as copolymers, terpolymers, et cetera, combinations of lactams, diacids, and diamines with lactams, multiple diacids, and dibases with lactams, et cetera. It is intended to include, but not to be limited to, the several such nylons or combinations thereof as given below.  
       [0037] For instance, various nylons may be polymers of the reaction products of diacids and dibases, which includes the polymer of the reaction product of adipic acid and hexamethylene diamine (commonly known as nylon 6,6), the polymer of the reaction product of sebacic acid and hexamethylene diamine (commonly known as nylon 6,10), and polymers of the reaction product of hexamethylenediamine and a 12-carbon dibasic acid (commonly known as nylon 6,12). Other nylons are polymers of the reaction product of lactams which include, but are not limited to, caprolactam (commonly known as nylon 6), the polycondensation product of the monomer 11-aminoundecanoic acid (commonly known as nylon 11), and the addition product of lauryllactam or cyclo-decalactam (both of which are commonly known as nylon 12). These and similar lactam copolymers are available with a wide variety of caprolactam and lauryllactam relative amounts. Other commercially available nylons include the copolymer made from caprolactam with adipic acid and hexamethylene diamine (commonly known as nylon 66612). Various nylons can also be copolymers of nylon 6 or nylon 6,6 and a nylon salt obtained by reacting a dicarboxylic acid component such as terephthalic acid, isophthalic acid, adipic acid, or sebacic acid with a diamine such as hexamethylene diamine, methaxylene diamine, or 1,4-dibaminomethylcyclohexane. Nylons also useful include nylon 6,9, nylon 6,10, nylon 6T, nylon 4,6 and copolymers thereof. Preferred nylons are nylon 6,6 and nylon 6.  
       [0038] Also, polyesters may be advantageously employed in the present invention. By polyester, it is intended to include copolymers and terpolymers thereof. Suitable polyesters include, but are not limited to, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), or a combination thereof.  
       [0039] The majority of carpet that has polyester face fiber contains polyethylene terephthalate as the polyester. However, it is noted that Shaw Industries, Inc. and Shell Chemicals sell carpet with face fiber made from CORTERRA®, which is a registered trademark of the Royal Dutch/Shell Group of companies for polytrimethylene terephthalate, namely the polymer reaction product of 1,3-propanediol and terephthalic acid. Additionally, it is noted that DuPont manufactures and sells the polymer reaction product of 1,3-propanediol and terephthalic acid under the trademark SORONA®, which reaction product DuPont also refers to as 3GT. Also known to be manufactured by DuPont is polybutylene terephthalate, the reaction product of 1,4-butanediol and terephthalic acid.  
       [0040] Furthermore, polypropylene may be advantageously employed in the present invention. By polypropylene, it is intended to include copolymers and terpolymers thereof. Particularly, PP may be employed if the face fiber is intended for a low-cost Berber-style loop-pile carpet.  
       [0041] Additionally, combinations of nylon, combinations of polyester, or combinations of polypropylene may be employed in the present invention.  
       [0042] More particularly with regard to the present invention, at least two polymers (which may be flakes, pellets, chips, and the like) are thoroughly mixed, such as in a blender. The blending may be at ambient conditions, free of added heat and/or added pressure.  
       [0043] The two polymers are of the same kind of polymer generic class, except that one is virgin polymer and one is recycle polymer.  
       [0044] Moreover, in the event that the two polymers are nylon, the two may also differ with regard to the meq/gm level of amine ends, or with regard to the level of sulfur from being complexed with a sulfonated compound. Additionally, the two may be different kinds of nylon, such as the virgin may be nylon 6 and the recycle may be nylon 6,6, or vice versa. However, it is preferred that the two nylons are the same kind. More particularly, nylon 6,6 and nylon 6 both have tight molecular structures, but nylon 6,6 is molecularly tighter than nylon 6. Mixing the two together may tend to interfere with crystallization, leaving a more open structure, which is less desirable than a filament product where both the virgin and the recycle are nylon 6,6, both the virgin and the recycle are nylon 6, and the like.  
       [0045] Specifically, when nylon is employed, and the resultant filament or fiber, as described below, is going to be dyed with cationic dye, then the virgin and the recycle should each be chosen for the respective amount of sulfur in each, which is based on the addition of a sulfonated compound (typically, SLIA and/or SSIA), with the objective that the resultant mixture should have a range of sulfur from about 1000 ppm to about 2600 ppm, more preferably from about 1300 ppm to about 2500 ppm, and most preferably from about 1500 ppm to about 2450 ppm. A range of about 2300 ppm+150 ppm is desirable for full cationic dyed fiber, whereas a range of about 1300 ppm+150 ppm is desirable for half cationic dyed fiber. In other words, for the nylon embodiment of the present invention, there is no need for all the nylon flakes being formed into filament to have the same level of being sulfonated for the filament to dye well with cationic dye.  
       [0046] Also, specifically, when nylon is employed, and the resultant filament or fiber, as described below, is going to be dyed with acid dye, then the virgin and the recycle should each be chosen for the respective amine ends of each with the objective that the combined virgin and recycle in the resultant mixture should have a range of amine ends from about 33 meq/gm to about 71 meq/gm, more preferably from about 42 meq/gm to about 62 meq/gm, and even more preferably from about 48 meq/gm to about 58 meq/gm. For instance, if the virgin nylon 6,6 flake had 30 meq/gm of amine ends whereas the recycle nylon 6 flake had 42 meq/gm of amine ends, and if the two were mixed in respective amounts of 75% by weight virgin and 25% by weight recycle, then the combined virgin and recycle in the resultant mixture would have 33 meq/gm of amine ends, whereas if the virgin nylon 6,6 flake had 80 meq/gm of amine ends whereas the recycle nylon 6 flake had 42 meq/gm of amine ends, and if the two were mixed in respective amounts of 75% by weight virgin and 25% by weight recycle, then the combined virgin and recycle in the resultant mixture would have 71 meq/gm of amine ends. Specifically, as can be seen below for a preferred embodiment as depicted in Example II, one nylon was virgin nylon 6,6 with 80 meq/gm of amine ends and the other nylon was recycle nylon 6,6 with 32 meq/gm of amine ends, where the combination of virgin and recycle in the mixture had 56 meq/gm. The range of about 30 to about 80 meq/gm for the amine ends in the virgin nylon covers what is generally commercially available for yarns made with virgin nylon, but no recycle nylon. In other words, for the nylon embodiment of the present invention, there is no need for all the nylon flakes being formed into filament to have the same level of amine ends for the filament to dye well with acid dye.  
       [0047] It is noted in connection with the dyeing of nylon fiber, as is known in the art, carpet tuft made from nylon fiber that is sulfonated so as to be cationic dyed in general will also have nylon fiber that is not sulfonated so as to be acid dyed. Having all the nylon fiber be sulfonated nylon for cationic dyeing is generally not practiced.  
       [0048] Next, the blended mixture of at least two polymers (one being virgin and one being recycle) is formed into colorable mono-component filaments. The blended mixture of virgin and recycle may be made into mono-component filaments, and the filaments are colored, such as by dyeing. Alternatively, as described in more detail below with respect to pigmented PP, a colorant, such as a pigment, may be included in the blended mixture of virgin and recycle, and the resultant made into mono-component filaments, which will be colored due to the presence of the pigment during making of the filaments, and thus need no further coloring.  
       [0049] More particularly with regard to forming the mixture of virgin and recycle into mono-component filaments, and then coloring the fiber, the following is the process in general. For instance, the mixture may be fed through an extruder to become a melt flow that goes into a spinneret and is extruded from the spinneret as a group of filaments. The extruded filaments are then quenched, for instance with air, in order to solidify them, and they are combined to make a yarn bundle or fiber.  
       [0050] The polymer mix may contain various additives or the fibers may be topically treated with various additives. Examples of typical additives include, but are not limited to, oil, stabilizers, soil repellants, antistatic agents, delustering agents, and the like. For instance, TiO2 is well known for use as a delustering agent used to impart wool-like luster in carpets and carbon is well known for use as an antistatic agent in carpets.  
       [0051] If the fibers are intended for carpets, subsequently the spun yarn is drawn and textured, and then either may be wound onto packages as BCF or may be cut and baled as staple. Staple is relatively short in length so it is not wound onto packages but rather is piddled onto a drum. The draw-texturing step may be coupled directly to the spinning step in order to eliminate the intermediate winding operation. The package of BCF is suitable for tufting into carpets. The bale of staple is suitable for spinning into yarn suitable for tufting into carpets.  
       [0052] In general for making BCF or spun staple yarn into carpet, the BCF or spun staple yarn is tufted through a pliable primary backing, such as jute, woven PP, or cellulosic non-wovens. Most commonly a woven PP fabric is used as the backing. Next, the backing is coated with a latex, for instance, SBR, vinylidene chloride polymer, or vinyl chloride-vinylidene chloride copolymer. Often, calcium carbonate or other filler is used to reduce the cost of the latex. Lastly, the typical step is application of a secondary backing that usually is woven jute or is woven or foamed synthetic, such as PP.  
       [0053] The BCF or staple may be dyed and then tufted into carpet. Alternatively, the BCF or staple may be tufted, and then dyed, such as by printing with the desired colorant.  
       [0054] Typically, the method of coloring filament or fiber for carpet involves dyeing by submersion of the fiber in a dye liquor, which may be done at atmospheric pressure or in a pressure vessel. Dye liquors are usually aqueous solutions of dyes, acid, sequestering agents, and wetting agents. The submersion dyeing process is usually with heat at a temperature above room temperature, with the particular temperature depending on which dye is used and what other chemicals are in the dye bath. Also, there are various non-submersion methods of dyeing. Such procedures for dyeing are standard and well known to those of ordinary skill in the art of carpet manufacture.  
       [0055] Amine groups. For dyeing of nylon filament or fiber with acid dye, one looks to what is colloquially known in the art as the amine ends, as noted above. More particularly, the level of amine ends is determined by a standard procedure, and is denoted in meq of amine ends per gm of nylon. The standard analytical procedure for determining the amine ends is as follows. The amine end group content in nylon is quantified by either potentiometric or conductometric titration principles utilizing an automatic or semi-automatic titro-processor linked to a compatible computer, which resolves titration curves and calculates results. The amine groups are calculated according to the following formula.  
       Amine Groups ( meq/gm )={End Point ( mL )×Normality HCl ( meq/mL )−Blank ( meq )}/Sample Weight ( gm )  
       [0056] Flake sample preparation begins with the nylon sample being dried for about 20 minutes at about 93+4° C. in a forced air oven and then cooled in a desiccator to assure&lt;about 0.4% moisture content. Yarn sample preparation begins with scouring off the finish, if present, using acetone followed by boiling water, and then the sample is dried for about 20 minutes at about 93+4° C. in a force air oven followed by cooling in a desiccator to assure&lt;about 0.4% moisture content. The meq/gm of amine ends represents the available dye sites in acid-dyeable nylon fiber, and should range from about 30 for light acid-dyeable nylon fiber to about 80 for deep acid-dyeable nylon fiber.  
       [0057] Additionally, three low-wet pickup methods are common for dyeing of acid-dyeable nylon fiber. A first method is space-dyeing in yarn form, where drops of different colors are applied along a threadline. A second method is printing in carpet form where a pattern is applied by pressing dyes through stencils or by a system similar to ink-jet printers used with computers. A third method is continuous dyeing in carpet form where dye films are applied via a dip-bath/nip-roll, film lay-down, or sprayer system. For each of the three, dye application is followed quickly by steaming, rinsing, and drying. Also, low-wet pickup systems offer less control as compared to standard acid dyeing and thus typically more precision is employed during low-wet pickup dyeing.  
       [0058] Sulfur level On the other hand, for dyeing of nylon filament or fiber with cationic dye, the amine end level is generally regarded as unimportant, and seldom is measured. Rather, the sulfur level is measured, and is considered quite important. More specifically, the nylon is complexed with a sulfonated compound (typically, SLIA and/or SSIA), so that the nylon is dyeable with cationic dyes. The standard analytical procedure for determining the sulfur level is as follows. Sulfur is one of the elements in nylon that is measured by x-ray fluorescence spectroscopy. The nylon sample is prepared as a smooth disc for presentation to the spectrometer and is exposed to a steady stream of primary x-rays from the spectrometer&#39;s x-ray tube. The sulfur in the sample is excited by these x-rays and emits its own characteristic x-ray radiation. A portion of these characteristic x-rays passes through a parallel collimator and is reflected by a specific analyzing crystal into the detector that is positioned by the instrument&#39;s goniometer at a specific angle (2 Θ) dependent on the element, sulfur in the present case. The x-rays are reflected from the crystal according to the Bragg Law (nλ=2 δ Sin Θ). The intensity of this characteristic radiation is directly proportional to the quantity of the element present in the sample. The test nylon is compared to nylon analytical standards. The result is reported in parts per million according to the following formula.  
         ppm ={(net units of sample)/(net units of standard)}×{standard value} 
       [0059] Sample preparation starts with melting the nylon in an aluminum dish in a laboratory oven set at about 328° C. and blanketed with nitrogen flowing at about 0.5 cfh. The sample is then cooled at room temperature and stripped of the aluminum dish. Finally, the sample&#39;s face is sanded smooth with 60-grit paper and placed immediately in the spectrometer for measurement.  
       [0060] However, cationic-dyeable nylon fiber can be stained by acid dyes in a mixed acid dye/cationic dye liquor, which may be desired. For instance, a mixed liquor is used when cationic-dyeable nylon fiber is cabled with acid-dyeable nylon fiber prior to dyeing. Such cabling of cationic-dyeable nylon fiber and acid-dyeable nylon fiber is typically employed for the face fiber of a carpet when the cationic-dyeable fiber is an accent, seldom over 25% by weight of the total carpet face fiber.  
       [0061] Commercial product offerings of cationic-dyeable nylon fiber from Solutia, Inc. are available in two dye depths, namely the full cationic-dyeable fiber where the nylon flake used to make the fiber has 2300+150 ppm sulfur and the half cationic-dyeable fiber where the nylon flake used to make the fiber has 1335+150 ppm sulfur. The full cationic-dyeable nylon fiber is generally impervious to acid-dye stains. On the other hand, the half cationic-dyeable nylon fiber is susceptible to acid-dye stains, and hence, used sparingly, with most of the use being when the susceptibility is desired such as for the above-noted cabling.  
       [0062] On the other hand, when polyester is the face fiber, it is colored differently from the way nylon as the face fiber is colored.  
       [0063] As noted above, polyester filament or fiber typically is beck dyed in a batch process with disperse dyes, since polyester has no dye sites like the amine ends that are dye sites in nylon. The disperse dyeing process may be with chemicals or heated pressure vessels. Typical chemicals are phenolic compounds and the phenolic dyeing is with heat at atmospheric pressure. The pressure vessel is called a jet beck, and often chemicals are not needed because of the pressure. The beck process swells portions of the polyester molecular chain so that the disperse dye is physically placed into the fiber. After the dyeing process is run, the dye bath is cooled resulting in the dye being entrapped into the fiber structure. Some polyesters, which are called carrierless, do not require phenolic based compounds in order to be dyed, and therefore are subject to the same types of disperse dyes as the other polyesters but can be disperse dyed via either a batch process (i.e., a beck process) or a continuous process. The remainder of the fiber forming process for PE would be substantially the same as described above.  
       [0064] When polypropylene is the face fiber, the coloring process is different from the dye bath process as described above. More specifically, polypropylene filament or fiber is pigmented. As noted above, during pigmenting, a colorant is admixed with the polymer flake, pellets, chips, or the like, and the resultant admixture made into colored fiber, such as by extrusion. The remainder of the fiber forming process for PP would be substantially the same as described above. It is noted that SDN is nylon that is pigmented in essentially the same manner by adding colorant during extrusion of fiber.  
       LABORATORY EXAMPLES 
     
    
    
     EXAMPLE I  
     [0065] (Nylon Dyed with Cationic Dye)  
     [0066] Selected weight percents of recycle nylon 6,6 flake were thoroughly mixed in a blender under ambient conditions with various weight percents of virgin nylon 6,6 flake, with the objective that the combination of recycle+virgin in each resultant mixture would contain about 2300 ppm sulfur, calculated on added SLIA.  
     [0067] The recycle nylon 6,6 flake was post-industrial waste nylon 6,6 from fiberstock off-specification yarn containing no dye, the fiberstock having been re-extruded and chopped so that it was converted back to flake and then sold by Barnet, Inc., of Arcadia, S.C., United States of America, as recycle under the product code NYL 880. The recycle nylon contained no sulfur.  
     [0068] The virgin nylon 6,6 flake was obtained from NPP in Gonzalez, Fla. Two different batches of virgin nylon 6,6 flake were employed, where each contained a different ppm of sulfur, calculated based on SLIA that had been added to the virgin nylon 6,6 flake. The virgin nylon 6,6 flake designated as regular contained about 2320 ppm sulfur, and the virgin nylon 6,6 flake designated as super contained about 9700 ppm sulfur. The sulfur level was determined in accordance with standard procedures as noted above.  
     [0069] For delustering, TiO2 is typically added during the polymerization process to make nylon. Each of the recycle nylon 6,6 flake and the regular virgin nylon 6,6 flake contained respectively about 0.3 weight % and about 0.4 weight % TiO2. However, the super virgin nylon 6,6 contained no TiO2.  
     [0070] Each mixture was melt extruded by conventional means at a temperature of about 280° C., and spun into fiber on conventional spinning machines. The extruded fibers were quenched with air for cooling in order to solidify them, and then wound on bobbins. Each run was conducted at the same or similar conditions, except that the persons operating the machinery had to adjust vent pressure since an increasing amount of vacuum was pulled in correlation to the increasing amount of recycle content for any particular sample.  
     [0071] The yarns from the bobbins were then further processed in a conventional manner by drawing and jet texturing. The resultant BCF had 68 filaments and was about 1360 denier.  
     [0072] For comparison, a sample was made from some of the regular virgin nylon 6,6 flake (free of any recycle nylon flake) that was also extruded and spun into fiber, followed by being quenched, wound, drawn, and jet textured. The resultant BCF had 68 filaments and was about 1360 denier. The comparison sample actually corresponded to a commercial yarn product that is manufactured and sold by Solutia, Inc. of Gonzalez, Fla. under the product code 1360-68-JBT, which is dyeable with cationic dye.  
     [0073] Each sample was space dyed in yarn form per standard procedures and patterns in a carpet-yarn space-dye operation with cationic dye. Applied were 4 different colors using fiber reactive dyes sold by FourColors of Dalton, Ga., United States of America, under the brand name FourTex. The dyes used were FourTex Yellow 2GR, FourTex Red BS, FourTex Navy SG, and FourTex Blue KR-150, using the same dye bath conditions of temperature, time, and weight % of dye for the test and comparison samples.  
     [0074] The dyed samples were viewed and it was subjectively determined that those containing recycle nylon 6,6 exhibited the characteristic of good colorability in that they accepted the dye well and looked comparable to the dyed comparison made from 100% virgin nylon (i.e., the dyed commercial product 1360-68-JBT). More specifically, the dyed samples were viewed by people of ordinary skill in the art of rating carpet quality, and it was subjectively determined that the dyed fiber of the recycle/virgin polymer mixture exhibited the characteristic of good colorability, including, but not limited to, such factors as depth of shade, vibrancy or color, demarcation of colors at print junctions, and carpet uniformity or freedom from streaks. It was subjectively determined that the characteristic of colorability of the dyed fiber from the recycle/virgin polymer were at least as good as the characteristic of colorability of dyed fiber from the 100% virgin polymer.  
     [0075] The results are summarized in Table I below, where each % is a % by weight.  
               TABLE I                          (Cationic Dye)                                             % Nylon   % Nylon                           6,6   6,6   % Nylon           Regular   Super   6,6   Sulfur   %   Accepted       Sample   Virgin   Virgin   Recycle   ppm   TiO2   Dye Well                                                 Com-   100   0   0   2320   0.4   Yes       parion       Mixture   67.1   7.9   25   2323   0.343   Yes       1       Mixture   47.4   12.6   40   2322   0.31   Yes       2       Mixture   35   15   50   2300   0.29   Yes       3       Mixture   21.1   18.9   60   2323   0.264   Yes       4                  
 
     EXAMPLE II  
     [0076] (Nylon Dyed with Acid Dye)  
     [0077] Recycle nylon 6,6 flake was thoroughly mixed in a blender under ambient conditions with an approximately equal amount by weight of virgin nylon 6,6 flake, with the objective that combination of recycle+virgin in the resultant mixture would contain about 56 meq/gm of amine ends. The recycle nylon 6,6 flake and the virgin nylon 6,6 flake respectively had 32 meq/gm amine ends and 80 meq/gm amine ends. The respective levels of amine ends were determined for each in accordance with standard procedures as noted above.  
     [0078] The recycle nylon 6,6 flake was post-industrial waste nylon 6,6 from fiberstock off-specification yarn containing no dye, the fiberstock having been re-extruded and chopped so that it was converted back to flake and then sold by Barnet, Inc., of Arcadia, S.C., United States of America as recycle under the product code NYL 880.  
     [0079] The virgin nylon 6,6 flake was obtained from NPP in Gonzalez, Fla. Also, the virgin nylon 6,6 flake was what is used to spin a commercial yarn product that is manufactured and sold by Solutia, Inc. of Gonzalez, Fla. under the product code 1360-86-NET deep dye, which is dyeable with acid dye.  
     [0080] For delustering, TiO2 is typically added during the polymerization process to make nylon. Each of the recycle nylon 6,6 flake and the virgin nylon 6,6 flake contained respectively about 0.3 weight % and about 0.4 weight % TiO2. Thus, the average was about 0.35 weight % TiO2 for the combined recycle and virgin in the mixture.  
     [0081] The mixture was melt extruded by conventional means at a temperature of about 280° C., and spun into fiber on a conventional spinning machine. The extruded fibers were quenched with air for cooling in order to solidify them, and then wound on bobbins. The yarns from the bobbins were then further processed in a conventional manner by drawing and jet texturing. The resultant BCF had 68 filaments and was about 1360 denier.  
     [0082] For comparison, a sample was made from a virgin nylon 6,6 flake having 56 meq/gm of amine ends (free of any recycle nylon flake) that also included about 0.3 weight % TiO2, as well as a standard carbon antistatic agent. The flake was also extruded and spun into fiber, followed by being quenched, wound, drawn, and jet textured. The resultant BCF had 68 filaments and was about 1360 denier.  
     [0083] The comparison sample actually corresponded to a commercial yarn product that is manufactured and sold by Solutia, Inc. of Gonzalez, Fla. under the product code 1360-68-KET, which is dyeable with acid dye.  
     [0084] Each run was conducted at the same or similar conditions, except that the persons operating the machinery had to adjust vent pressure for an increased amount of vacuum for the mixture containing recycle. Also, the comparison sample was produced on a machine that receives polymer for a continuous polymerizer, rather than from an extruder. The continuous polymerizer line takes the raw materials all the way to filament, eliminating the steps of forming and remelting flake. Nevertheless, from the meter pump to the finished product, the two processes (the extruder and the continuous polymerizer) are the same, and hence, switching production between continuous polymerizer-fed and extruder-fed machines is comnion practice among fiber producers, well known to the person of ordinary skill in the art.  
     [0085] Each of the mixture sample and the comparison sample was dyed with acid dye on a commercial carpet jet-printing system, using the same dye bath conditions of temperature, time, and weight % of dye for the test and comparison samples. More specifically, each sample was tufted into carpet before dyeing, and then printed per standard procedures and patterns in a jet-printing operation set up for carpets. The jet printer had a color bank of dyes from Ciba Specialty Chemical Corporation of Dalton, Ga., United States of America. The dyes are sold under the brand names Erionyl for acid milling dyes and Irgalan for premetalized acid dyes. Examples of Erionyl colors used were Black MR, Blue P2R, Red A-3B, and Yellow A3G. Examples of Irgalan colors used were Black BGL, Blue 3GL, Bordeaux EL 200, Red B, and Yellow 2GL KWL 250.  
     [0086] The dyed samples were viewed and it was subjectively determined that the dyed fiber from the mixture exhibited the characteristic of good colorability in that the dyed fiber from the mixture accepted the dye well and looked comparable to the dyed comparison made from 100% virgin nylon (i.e., the dyed commercial product 1360-68-KET). More specifically, the dyed samples were viewed by people of ordinary skill in the art of rating carpet quality, and it was subjectively determined that the dyed fiber of the recycle/virgin polymer mixture exhibited the characteristic of good colorability, including, but not limited to, such factors as depth of shade, vibrancy or color, demarcation of colors at print junctions, and carpet uniformity or freedom from streaks. It was subjectively determined that the characteristic of colorability of the dyed fiber from the recycle/virgin polymer were at least as good as the characteristic of colorability of dyed fiber from the 100% virgin polymer.  
     [0087] The results are summarized in Table 11 below, where each % is a % by weight.  
               TABLE II                          (Acid Dye)                             Comparison   Blend                                     % virgin nylon 6,6 (56 meq/gm amine ends)   100   0       % virgin nylon 6,6 (80 meq/gm amine ends)   0   50       % recycle nylon 6,6 (32 meq/gm amine ends)   0   50       meq/gm amine ends   56   56*       % TiO2   0.4   0.35       accepted dye well   Yes   Yes                          
 
     [0088] Although the present invention has been shown and described in detail with regard to only a few exemplary embodiments of the invention, it should be understood by those skilled in the art that it is not intended to limit the invention to the specific embodiments disclosed. Various modifications, omissions, and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. Accordingly, it is intended to cover all such modifications, omissions, additions, and equivalents as may be included within the spirit and scope of the invention as defined by the following claims.