US20220290367A1

US20220290367A1 - Carpet made from self-bulking ptt-containing bicomponent fibers

Info

Publication number: US20220290367A1
Application number: US17/635,873
Authority: US
Inventors: Dennis Gerard Madeleine
Original assignee: Covation Inc
Current assignee: Covation Inc
Priority date: 2019-12-10
Filing date: 2020-12-08
Publication date: 2022-09-15
Also published as: CA3152951A1; AU2020402757A1; JP2023506733A; KR20220104699A; CN114787433A; MX2022006779A; BR112022007903A2; EP4073301A1; WO2021118985A1; TW202129105A

Abstract

Disclosed herein are carpets whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer and a second component of poly(trimethylene terephthalate) polymer or a blend of poly(trimethylene terephthalate) with poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, wherein the bicomponent fiber is self-bulking due to differential shrinkage. Also disclosed is an improved process for making a yarn to produce a carpet whose face fiber comprises a self-bulking bicomponent fiber comprising one component of poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer and a second component of poly(trimethylene terephthalate) or a blend of poly(trimethylene terephthalate) with poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to carpet and, more particularly, to carpet whose face fiber comprises self-bulking poly(trimethylene terephthalate) (PTT)-containing bicomponent fibers.

BACKGROUND

In the fabrication of modern carpets, it is common to use synthetic polymers (e.g. nylon, polyester, polypropylene) to make fibers possessing high levels of bulk, which can be defined as the enhanced covering power or apparent volume of the fiber compared to unbulked or “flat” fiber. These bulked continuous fibers (“BCF”) are typically monocomponent fibers manufactured on a spinning machine with a high temperature/pressure jet and cooling drum specifically designed to mechanically impart bulk to the fiber. This process has several disadvantages. The high temperatures, pressure and turbulence of the fiber within the jet can damage the fiber filaments and adversely affect physical properties of the fiber. Furthermore, the need to impart bulk by the jet/drum process necessitates a decrease in fiber production speed compared to other spinning processes wherein the need for mechanical bulk is not required, i.e., fully drawn yarn (“FDY”) or partially oriented yarn (“POY”) flat yarns.
One way to characterize textile fibers is by their amount of crimp. “Crimp” refers to the waviness of a fiber and can be expressed as number of crimps per unit length. The amount of crimp, also referred to herein as “crimp contraction”, can be expressed by comparing the extended length of the fiber under load to the retracted length of the fiber without the load. The amount of crimp in a fiber can be naturally occurring (e.g. wool) or imparted to a synthetic fiber in manufacturing to suit the desired end-use. Crimp can be generated using air and heat in a bulking jet (BCF), twisting/untwisting of a POY on a false twist texturing machine to make draw textured yarn (DTY), or by differential shrinkage in a side by side or eccentric sheath/core bicomponent fiber. Low levels of crimp correspond to textile fibers that have improved loft or bulk, and are desirable when fabric opacity or coverage is important. Alternatively, high levels of crimp result in fibers with significant levels of stretch and recovery and are valuable in apparel applications.
In carpet applications, lower levels of crimp are desirable to impart high bulk without appreciable development of stretch. Self-crimping high bulk yarns comprising bicomponent filaments for use in fabrics are described in U.S. Pat. No. 7,790,282. In apparel fabrics, side by side and eccentric sheath/core type bicomponent fiber crimp properties are typically maximized to provide high levels of stretch in the fiber and resulting fabrics. U.S. Pat. No. 6,803,102 B1 issued to Talley et al. on Oct. 12, 2004 is exemplary of producing bicomponent fibers with asymmetric fiber cross sections and as incorporated herein in its entirety.
U.S. Pat. No. 6,158,204 issued to Talley et al. on Dec. 12, 2000, discloses a self-setting yarn made from bicomponent fibers that form helical crimps that lock in twist and form bulk. Also disclosed is using such yarn in carpet and textiles. A variety of polymers are disclosed such as poly(ethylene terephthalate) (“PET), poly(butylene terephthalate) (“PBT”), polypropylene, nylon, and the like. However, the use of poly(trimethylene terephthalate) (PTT) is not disclosed.
U.S. Pat. No. 5,645,782 Howell et al., U.S. Pat. No. 6,109,015 Roark et al. and U.S. Pat. No. 6,113,825 Chuah; WO 99/19557 Scott et al.; H. Modlich, “Experience with Polyesters Fibers in Tufted Articles of Heat-Set Yarns, Chemiefasern/Textilind. 41/93, 786-94 (1991); and H. Chuah, “Corterra Poly(trimethylene terephthalate)—New Polymeric Fiber for Carpets”, The Textile Institute Tifcon '96 (1996) (available at http://www.shellchemicals.com/corterra/0,1098,281,00.html), all of which are incorporated herein by reference, describe carpets made with poly(trimethylene terephthalate) (PTT) homofibers but no bicomponent fibers.
There is disclosed herein a carpet whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene) terephthalate (PTT) or a blend of PTT with PET homopolymer or PET copolymer (co-PET), wherein the bicomponent fiber is self-bulking due to differential shrinkage, in contrast to carpet whose face fiber is made from bulk continuous homofilament that is mechanically bulked.

SUMMARY

In a first embodiment, there is disclosed herein a carpet whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene terephthalate) (PTT) polymer or a blend of PTT with PET homopolymer or PET copolymer (co-PET), wherein the bicomponent fiber is self-bulking due to differential shrinkage, in contrast to carpet whose face fiber is made from bulk continuous homofilament that is mechanically bulked.
In a second embodiment, the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath/core configuration.
In a third embodiment, the first and second components of the bicomponent fiber can be present in a weight ratio ranging from 80:20 to 20:80.
In a fourth embodiment, the self-bulking bicomponent fiber disclosed herein has a crimp contraction after heating that is equal to or less that 30% as determined according to the Crimp Contraction Method disclosed herein.
In a fifth embodiment, there is disclosed an improved process for making a yarn to produce a carpet whose face fiber comprises a self-bulking bicomponent fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene terephthalate) (PTT) or a blend of PTT with PET homopolymer or PET copolymer (co-PET), said process comprising:
a) extruding the two components on a spinning machine capable of producing two or more independent melt streams;
b) combining the melt streams in a spinneret suited for making bicomponent fibers;
c) quenching in air the self-bulking bicomponent fibers produced in step (b);
d) drawing and heat setting the self-bulking bicomponent fibers; and
e) winding up the self-bulking bicomponent fibers by suitable means for subsequent processing into carpet,
wherein the self-bulking bicomponent fibers eliminate the need for a mechanical bulking step.
In a sixth embodiment, the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath core configuration.
In a seventh embodiment, the first and second components of the bicomponent fiber can be arranged in a weight ratio ranging from 80:20 to 20:80.
In an eighth embodiment, the self-bulking bicomponent fiber disclosed herein has a crimp contraction after heating which is equal to or less than 30% as determined according to the Crimp Contraction Method disclosed herein.

DETAILED DESCRIPTION

All patents, patent applications, and publications cited are incorporated herein by reference in their entirety.
As used herein, the term “embodiment” or “disclosure” is not meant to be limiting, but applies generally to any of the embodiments defined in the claims or described herein. These terms are used interchangeably herein.
In this disclosure, a number of terms and abbreviations are used. The following definitions apply unless specifically stated otherwise.
The articles “a”, “an”, and “the” preceding an element or component are intended to be nonrestrictive regarding the number of instances (i.e., occurrences) of the element or component. Therefore “a”, “an”, and “the” should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.
The term “comprising” means the presence of the stated features, integers, steps, or components as referred to in the claims, but that it does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. The term “comprising” is intended to include embodiments encompassed by the terms “consisting essentially of” and “consisting of”. Similarly, the term “consisting essentially of” is intended to include embodiments encompassed by the term “consisting of”.
Where present, all ranges are inclusive and combinable. For example, when a range of “1 to 5” is recited, the recited range should be construed as including ranges “1 to 4”, “1 to 3”, “1-2”, “1-2 & 4-5”, “1-3 & 5”, and the like.
As used herein in connection with a numerical value, the term “about” refers to a range of +1-0.5 of the numerical value, unless the term is otherwise specifically defined in context. For instance, the phrase a “pH value of about 6” refers to pH values of from 5.5 to 6.5, unless the pH value is specifically defined otherwise. It is intended that every maximum numerical limitation given throughout this
Specification includes every lower numerical limitation, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this specification will include every higher numerical limitation, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this Specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.
The term “bicomponent fiber” as used herein refers to a fiber being comprised of two different polymer components which may be composed of different polymer types, the same polymer type but having different intrinsic viscosities, or blends of two or more polymers, extruded from the same spinneret with both polymers within the same filament. Bicomponent fibers may also be referred to as composite fibers and the terms can be used interchangeably.
The term “BCF” refers to bulk or bulked continuous homofilament. It is essentially one long continuous strand of fiber that is used to make carpet. The terms “bulk” and “bulked” are used interchangeably herein.
The term “carpet” as used herein refers to floor coverings consisting of pile yarns or fibers and a backing system. The may be tufted or woven. As used herein, the term “carpet” encompasses wall-to-wall carpet, carpet tiles, rugs, and mats for vehicles and building entrances, for example those designed to capture foot soil.
The term “face” refers to the side of the carpet containing tufted or woven yarns.
The term “face fiber” as used herein refers to the fiber content of the carpet including that which is visible to the observer. The face fiber is primarily made up of yarns, and those yarns may be styled as cut, loop, cut and loop or any number of styles known to those skilled in the art.
The term “copolymer” refers to a polymer composed of a combination of more than one monomer. Copolymers can form the basis of some manufactured fibers.
The term “crimp” refers to the waviness of a fiber expressed as crimps per unit length. “Crimping” is the process of imparting crimp to filament yarn.
The term “crimp contraction” is a measure of fiber crimp and refers to the contraction in length of a yarn from the fully extended state (i.e., where the filaments are substantially straightened). This is due to the formation of crimp in individual filaments under specified conditions of crimp development. It is expressed as a percentage of the extended length. Crimp contraction can be measured before and/or after treatment of a fiber, for example by heating, to partially or fully develop the crimp; typically the crimp contraction after heating is of more interest and provides more information as it includes the crimp developed by heating. Unless specified otherwise, crimp contraction values disclosed herein are crimp contraction values after heating (Cca).
The term “denier” is a weight-per-unit-length measure of any linear material.
The term “fiber” refers to unit of matter, either natural or synthetic, that forms the basic element of fabrics and other textile structures. It is characterized by having a length at least 1000 times its diameter or width.
Typically textile fibers are units that can be spun into a yarn or made into a fabric by various methods including weaving, knitting, braiding, felting and twisting. Fiber is characterized by its denier (weight in grams per 9000 meters of fiber) and the number of filaments contained in the fiber.
The “filament” refers to a fine thread or continuous strand of fiber. There are two types of filaments: mono-filament and multi-filament. Filaments are characterized by their denier per filament (“dpf”).
The term “homofilament” means that the filament is made from one polymer type.
“Staple” refers to either natural fibers or cut lengths from filaments.
The term “intrinsic viscosity” (“IV”) refers to the ratio of specific viscosity of a solution of a known concentration to the concentration of solute extrapolated to zero concentration.
The term “tufting” refers to a process of creating textiles, such as carpet, on specialized multi-needle machines. A “tuft” is a cluster of soft yarns drawn through a fabric and projecting from the surface in the form of cut yarns or loops.
The cut or uncut loops form the face of a tufted or woven carpet.
The term “yarn” refers to a collection of individual filaments, either singly, or plied together with another collection of filaments. The terms “fibers” and “yarns” are used interchangeably herein.
The term “quenching” refers to rapid cooling in water, oil or air to obtain certain physical or material properties.
The term “poly(ethylene terephthalate)” or PET means polymer derived from substantially only ethylene glycol and terephthalic acid (or equivalent, such as dimethyl terephthalate), and is also referred to as poly(ethylene terephthalate) homopolymer. As used herein, the term “poly(ethylene terephthalate) copolymer” or “co-PET” refers to polymer comprising repeat units derived from ethylene glycol and terephthalic acid (or equivalent) and also containing at least one additional unit derived from an additional monomer, such as isophthalic acid (IPA) or cyclohexanedimethanol (CHDM). Poly(ethylene terephthalate) copolymer can contain from about 1 mole % to about 30 mole % additional monomer, for example from about 1 mole % to about 15 mole % additional monomer.
The term “poly(butylene terephthalate)” or PBT means polymer derived from substantially only 1,4-butanediol and terephthalic acid, and is also referred to as poly(butylene terephthalate) homopolymer. As used herein, the term “poly(butylene terephthalate) copolymer refers to polymer comprising repeat units derived from 1,4-butanediol and terephthalic acid and also containing at least one additional unit derived from an additional monomer, for example a comonomer for PTT copolymers as disclosed herein.
The term “poly(trimethylene terephthalate)” or PTT refers to a polyester made by polymerizing 1,3-propanediol and terephthalic acid. It is distinguished by its high elastic recovery and resilience. PTT is known to provide stain resistance, static resistance, and improved dyeability. The term “poly(trimethylene terephthalate) homopolymer” means polymer of substantially only 1,3-propanediol and terephthalic acid (or equivalent). The term “poly(trimethylene terephthalate)” also includes PTT copolymers, by which is meant polymer comprising repeat units derived from 1,3-propanediol and terephthalic acid (or equivalent) and also containing at least one additional unit derived from an additional monomer. Examples of PTT copolymers include copolyesters made using 3 or more reactants, each having two ester forming groups. For example, a copoly(trimethylene terephthalate) can be used in which the comonomer used to make the copolyester is selected from the group consisting of linear, cyclic, and branched aliphatic dicarboxylic acids having 4-12 carbon atoms (for example butanedioic acid, pentanedioic acid, hexanedioic acid, dodecanedioic acid, and 1,4-cyclo-hexanedicarboxylic acid); aromatic dicarboxylic acids other than terephthalic acid and having 8-12 carbon atoms (for example isophthalic acid and 2,6-naphthalenedicarboxylic acid); linear, cyclic, and branched aliphatic diols having 2-8 carbon atoms (other than 1,3-propanediol, for example, ethanediol, 1,2-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, and 1,4-cyclohexanediol), and aliphatic and aromatic ether glycols having 4-10 carbon atoms (for example, hydroquinone bis(2-hydroxyethyl) ether, or a poly(ethylene ether) glycol having a molecular weight below about 460, including diethylene ether glycol). The comonomer typically is present in the copolyester at a level in the range of about 0.5 mole % to about 15 mole %, and can be present in amounts up to about 30 mole %.
The term “Triexta” refers to a generic name for PTT, a subclass of polyester. The terms Triexta and PTT can be used interchangeably herein.
Poly(trimethylene terephthalate) has an intrinsic viscosity that typically is about 0.5 deciliters/gram (dl/g) or higher, and typically is about 2 dl/g or less.
The poly(trimethylene terephthalate) preferably has an intrinsic viscosity that is about 0.7 dl/g or higher, more preferably 0.8 dl/g or higher, even more preferably 0.9 dl/g or higher, and typically it is about 1.5 dl/g or less, preferably 1.4 dl/g or less, and commercial products presently available have intrinsic viscosities of 1.2 dl/g or less. Poly(trimethylene terephthalate) is commercially available from E. I. du Pont de Nemours and Company, Wilmington, DE under the trademark “Sorona®”.
Carpets made with poly(trimethylene terephthalate) homofibers and manufacture thereof, as well as the fibers and manufacture of the fibers, are described in U.S. Pat. No. 5,645,782 Howell et al., U.S. Pat. No. 6,109,015 Roark et al. and U.S. Pat. No. 6,113,825 Chuah; U.S. Pat. Nos. 6,740,276, 6,576,340, and 6,723,799; WO 99/19557 Scott et al.; H. Modlich, “Experience with Polyesters Fibers in Tufted Articles of Heat-Set Yarns, Chemiefasern/Textilind. 41/93, 786-94 (1991); and H. Chuah, “Corterra Poly(trimethylene terephthalate)—New Polymeric Fiber for Carpets”, The Textile Institute Tifcon '96 (1996), all of which are incorporated herein by reference. Staple fibers are primarily used to prepare residential carpets. BCF yarns are used to prepare all types of carpets and are usually preferred for carpets.
Typically, PTT-containing bicomponent fiber is used to make fabrics and apparel having durable stretch attributes. In contrast, such stretch attributes are not needed in the manufacture of carpet. Rather, fibers for use in making carpet are typically mechanically bulked to provide high levels of bulk; such fibers are typically referred to as “BCF” fibers.
Disclosed herein is a carpet whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene terephthalate) (PTT) or a blend of PTT with PET homopolymer or PET copolymer (co-PET), wherein the bicomponent fiber is self-bulking due to differential shrinkage, in contrast to carpet whose face fiber is made from bulk continuous homofilament that is mechanically bulked.
Also disclosed is an improved process for making a yarn to produce a carpet whose face fiber comprises a self-bulking continuous fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene terephthalate) (PTT) or a blend of PTT with PET homopolymer or PET copolymer (co-PET), said process comprising:

- a) extruding the two components on a spinning machine capable of producing two or more independent melt streams;
- b) combining the melt streams in a spinneret suited for making bicomponent fibers;
- c) quenching in air the self-bulking bicomponent fibers produced in step (b);
- d) drawing and heat setting the self-bulking bicomponent fibers; and
- e) winding up the self-bulking bicomponent fibers by suitable means for subsequent processing into carpet,

wherein the self-bulking bicomponent fibers eliminate the need for a mechanical bulking step.
The bicomponent fiber described herein can be in a side-by-side (“S/S”) or an eccentric sheath core (“S/C”) arrangement. The bicomponent fiber can be made in a variety of cross-sectional shapes, for example round, delta, trilobal, scalloped, or other shapes, by using spinnerets specific for each shape, for example as disclosed in U.S. Pat. No. 6,803,102, which is incorporated herein in its entirety.
Typically, fiber used for carpet is homofilament which is subjected to a mechanical bulking step in the manufacturing process. In contrast, the carpet described herein whose face fiber comprises a self-bulking continuous fiber comprising a bicomponent fiber comprising poly(trimethylene) terephthalate is self-bulking due to differential shrinkage.
As noted above, one the of components of the self-bulking bicomponent fiber is PTT or a blend of PTT with PET or with co-PET. Due to the unique shrinkage properties of PTT compared to other commercially available polyesters, PTT can be very effective for providing crimp. The other component of the self-bulking bicomponent fiber is PET or co-PET, and as the shrinkage thereof is minimal compared to PTT, this combination of components allows for maximal difference in shrinkage and therefore developed crimp. In contrast, poly(butylene terephthalate) (PBT) is less preferred as a component for use with PTT or PTT/PET blends to make self-bulking bicomponent fibers, as the PBT, PTT, and PTT/PET blends will shrink significantly, resulting in low differential shrinkage between the two components and therefore low crimp development in the resulting bicomponent fiber. For instance, at equal polymer weight ratios in a side by side or eccentric sheath/core self-bulking bicomponent fiber, a bicomponent fiber comprising PTT and PET as the two components will provide higher bulk than a bicomponent fiber comprising PBT and PET as the two components, or a bicomponent fiber comprising two different PET's each having a different intrinsic viscosity (IV) as the two components. Nylon polymers, including nylon 6 and nylon 66, may also be used as a first component in self-bulking bicomponent fibers; however, nylon polymers generally do not have sufficient adhesion with polyester as the second component, and may split and crack when subjected to stress. For this reason, bicomponent fibers comprising nylon and polyester may not be an optimal choice for carpet yarns.
The two components PET or co-PET, and PTT or a blend of PTT with PET or coPET, can be present in the self-bulking bicomponent fiber in a weight ratio ranging from 80:20 to 20:80. For example, the weight ratio of the first and second components can be 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80, or any ratio within this range. In one embodiment, the weight ratio of the first and second components is about 50:50.
For use in carpet, the self-bulking bicomponent fiber has a crimp contraction value after heating of 30% or less. Crimp contraction after heating can be measured by the crimp contraction method disclosed in the Examples section, below. There are several ways that the two components of the bicomponent fiber can be adjusted to achieve the desired crimp contraction after heating of 30% or less in the resulting bicomponent fiber. One option is to adjust the polymer intrinsic viscosity (IV) of each component relative to the other. For instance, if the difference in IV is very large between the two components of the bicomponent fiber, then high levels of differential shrinkage can occur between the two components, resulting in high crimp values and fiber stretch properties which are not suitable for making carpet. In contrast, if the IV difference is too small between the two components, then no substantial difference in shrinkage between the two components will occur, resulting in little to no bulk. Another way to produce bicomponent fibers with the preferred crimp level is to vary the weight ratio of the two components. If the bicomponent fiber contains a significant proportion of PTT, then the resulting fiber can have high crimp values and fiber stretch. Conversely, a very low amount of PTT in the volume ratio may not provide enough bulk or crimp contraction after heating to achieve the desired level.
A third way to produce bicomponent fibers with the preferred crimp level is to employ a PET/PTT blend at a fixed ratio (e.g. 50/50 weight ratio of PTT and PET) as one component, with PET as the second component. It was found that blending PET and PTT in one component can be used to modify the high shrinkage properties of PTT alone. When a bicomponent is manufactured with one component comprising a blend of PTT and PET, with the second component being PET, then it is possible to make fibers with an equal weight ratio (e.g. 50/50 w/w component 1 to component 2) that provide the desired levels of crimp, that is, a crimp contraction after heating of 30% or less. With some spinneret designs, it may be desirable to make bicomponent fibers with nearly equal weight ratio of the two components, and blending the PET with PTT is one way to achieve this outcome.
Alternatively, useful bicomponent fibers as disclosed herein can be made by varying the composition of the PTT/PET blend in one component of the bicomponent fiber where the second component is PET or co-PET. This approach can be used to make useful bicomponent fibers where high levels of PET may be desired. In summary, varying polymer type, IV, weight ratio, and blend composition are all techniques by which self-bulking bicomponent fibers can be designed to attain target crimp values that result in desirable carpet bulk. Changing relative speeds of the rolls and/or winder during fiber production could also affect crimp contraction.
One benefit of PTT in the self-bulking bicomponent fibers disclosed herein is the high level of shrinkage it provides compared to PET. Relatively small amounts of PTT can be used as one component of the self-bulking bicomponent fiber to generate bicomponent fibers with the desired bulk. However, too high a level of PTT content in the bicomponent fiber can result in levels of stretch which are too high to be useful in carpet yarns, and which would be better suited for apparel uses.
Various additives may be added to one or both polymers. These include, but are not limited to, lubricants, nucleating agents, antioxidants, ultraviolet light stabilizers, pigments, dyes, antistatic agent, soil resists, stain resists, antimicrobial agents, and flame retardants.
For use in carpet, the self-bulking bicomponent fibers disclosed herein can have a denier in the range of about 300 to about 1400 grams/denier. Useful denier per filament can be in the range of from about 2 to about 20.
In one embodiment of a carpet whose face fiber comprises a bicomponent fiber comprising one component of PET homopolymer or coPET and a second component of PTT or a blend of PTT with PET homopolymer or coPET, wherein the bicomponent fiber is self-bulking due to differential shrinkage, the one component comprises PTT having an intrinsic viscosity in the range of about 0.9 dL/g to about 1.25 dL/g and the second component comprises PET having an intrinsic viscosity of about 0.64 dL/g, and the weight ratio of the two components is about 50/50.
In another embodiment, one component comprises PTT having an intrinsic viscosity in the range of about 0.9 dL/g to about 1.0 dL/g and the second component comprises PET having an intrinsic viscosity of about 0.5 dL/g, and the weight ratio of the two components is in the range of about 20/80 to about 30/70.
In an additional embodiment, one component comprises a 50/50 weight/weight blend of PTT and co-PET, wherein the PTT has an intrinsic viscosity in the range of about 0.9 dL/g to about 1.0 dL/g and the co-PET has an intrinsic viscosity in the range of about 0.75 dL/g to about 0.85 dL/g, and the second component comprises PET having an intrinsic viscosity of about 0.5 dL/g, and the weight ratio of the two components is in the range of about 70/30 to about 30/70.
In a further embodiment, one component comprises a blend of PTT and co-PET, wherein the PTT has an intrinsic viscosity in the range of about 0.9 dL/g to about 1.0 dL/g and the co-PET has an intrinsic viscosity in the range of about 0.75 dL/g to about 0.85 dL/g, and wherein the weight ratio of PTT and Co-PET in the blend is in the range of from about 10/90 to about 90/10, and the second component comprises PET having an intrinsic viscosity of about 0.5 dL/g, and the weight ratio of the two components is about 50/50.
Fibers may be made by delivering the polymers to a spinneret in the desired volume or weight ratio. While any conventional multicomponent spinning technique may be used, an exemplary spinning apparatus and method for making bicomponent fibers is described in U.S. Pat. No. 5,162,074, to Hills. The self-bulking bicomponent fibers disclosed herein can be used in conjunction with all other types of fibers, synthetic and natural, used in making carpets. Carpets can be made through mechanical or hand tufting, weaving and hand knotting. Examples include 1) broadloom carpets (also known as wall-to-wall carpets) where a tufted carpet is made in long continuous lengths that are several meters wide for home and commercial applications, 2) carpet tiles produced in squares of various sizes for ease of installation, 3) rugs for home use, and 4) mats for vehicles and building entrances, designed to capture foot soil prior to building entry.
Any method known in the art of preparing carpet from a fiber could be used in preparing the carpets described herein. Typically, the self-bulking bicomponent fibers disclosed herein can be used in the same carpet manufacturing processes where other synthetic and natural fibers are employed. The bicomponent fiber can be used by itself in carpet fabrication (i.e. as a “singles” yarn) or plied together with more of the same bicomponent fiber or other fiber types (e.g. nylon, polypropylene, polyester) to increase denier. Optionally, the singles and plied fiber may be entangled with an air jet prior to plying and may also be subjected to heat setting by machines specifically designed to thermally set the singles and tufted yarn physical properties. One example of a heat setting machines suited for this purpose is manufactured by Superba® (Muhouse, France). Whether the bicomponent fibers are optionally air entangled, plied or heat set, the fibers can then be tufted into standard nonwoven or woven backing sheets typical of the carpet industry. The face fiber loops in the tufted carpet may be severed to provide a cut loop carpet. After tufting, adhesive is often applied to the backside of the carpet (i.e. opposite side from the face fiber) to hold the tufts in place. An additional backing layer may also be added to the carpet back side. The adhesive layer may contain fillers or flame retardants, depending on the specific carpet end use. The carpet may then be subjected to dyeing by standard processes common to the carpet fabrication industry; alternatively, pigments may be added during fiber extrusion to the bicomponent fiber and/or to the companion fibers to impart color to the finished fabrics. In addition, the face yarns may be treated with materials designed to impart fire resistance, anti-static properties or stain and soil resistance. The finished carpet is often dried to remove water remaining from the dyeing process.
The manufacturing process described above is typical for broadloom tufted carpets. Variations to this process known in the industry may be employed in the production of rugs, carpet tiles, and vehicle mats.
One feature of the bicomponent fibers disclosed herein is development the crimp and bulk by elevating the temperature of the fiber to at least 75° C. but less than 200° C. During the optional heat setting, dyeing and drying steps, the bicomponent fiber will be subjected to this temperature range in the standard course of carpet production. Alternatively, the carpet can be subjected to a separate heating step to develop bulk or the bicomponent fiber (singles or plied) can be heat treated to develop bulk.
The face fiber comprising bicomponent fiber may have circular or non-circular cross-section, such as trilobal. It should have a crimp contraction after heating value equal to or less than 30%.
An advantage of the carpet disclosed herein is that there is no need for mechanical bulking of yarn used to make the carpet as the bicomponent fiber is self-bulking due to its differential shrinkage. In contrast, carpet yarn made from bulk continuous homofilament will require mechanical bulking because it is not capable of differential shrinkage. In other words, a step of mechanical bulking of continuous homofilament is eliminated by the use of bicomponent fibers having differential shrinkage to make carpet.
Optionally, a carpet whose face fiber comprises a self-bulking bicomponent fiber as disclosed herein may further comprise at least one additional fiber. The at least one additional fiber may be plied together with the self-bulking bicomponent fiber to increase denier, for example, or may be used as an additional carpet yarn when the carpet is tufted. The at least one additional fiber may be selected from bulked continuous filament (that is, homofilament), synthetic staple fiber, and natural fiber. In one embodiment, the at least one additional fiber is bulked continuous filament, and the bulked continuous filament comprises nylon, polypropylene, or polyester. In another embodiment, the at least one additional fiber is synthetic staple fiber, and the synthetic staple fiber comprises nylon or polyester. In a further embodiment, the at least one additional fiber is natural fiber, and the natural fiber comprises wool, silk, or cotton.
Non-limiting examples of the embodiments disclosed herein include:
1. A carpet whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene) terephthalate (PTT) or a blend of poly(trimethylene terephthalate) (PTT) with poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET), wherein the bicomponent fiber is self-bulking due to differential shrinkage, in contrast to carpet whose face fiber is made from bulk continuous homofilament that is mechanically bulked.
2. The carpet of embodiment 1 wherein the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath core configuration.
3. The carpet of embodiment 1 or 2, wherein the first and second components of the bicomponent fiber are present in a weight ratio ranging from 80:20 to 20:80.
4. The carpet of embodiment 1, 2, or 3 wherein the crimp contraction after heating of the bicomponent fiber is equal to or less than 30% as determined according to the Crimp Contraction Method.
5. The carpet of embodiment 1, 2, 3, or 4, wherein the face fiber further comprises at least one additional fiber selected from bulked continuous filament, synthetic staple fiber, and natural fiber.
6. The carpet of embodiment 5, wherein the at least one additional fiber is bulked continuous filament, and the bulked continuous filament comprises nylon, polypropylene, or polyester.
7. The carpet of embodiment 5, wherein the at least one additional fiber is synthetic staple fiber, and the synthetic staple fiber comprises nylon or polyester.
8. The carpet of embodiment 5, wherein the at least one additional fiber is natural fiber, and the natural fiber comprises wool, silk, or cotton.
9. An improved process for making a yarn to produce a carpet whose face fiber comprises a self-bulking bicomponent fiber comprising one component of poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer and a second component of poly(trimethylene terephthalate) or a blend of poly(trimethylene terephthalate) with poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, said process comprising:

- a) extruding the two components on a spinning machine capable of producing two or more independent melt streams;
- b) combining the melt streams in a spinneret suited for making bicomponent fibers;
- c) quenching in air the self-bulking bicomponent fibers produced in step (b);
- d) drawing and heat setting the self-bulking bicomponent fibers; and
- e) winding up the self-bulking bicomponent fibers by suitable means for subsequent processing into carpet, wherein the self-bulking bicomponent fibers eliminate the need for a mechanical bulking step.

10. The improved process of embodiment 9, wherein the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath core configuration.
11. The improved process of embodiment 9 or 10, wherein the first and second components of the bicomponent fiber are present in a weight ratio ranging from 80:20 to 20:80.
12. The improved process of embodiment 9, 10, or 11, wherein the crimp contraction after heating of the bicomponent fiber is equal to or less that 30% as determined according to the Crimp Contraction Method.

EXAMPLES

The disclosure is further defined in the following Examples. It should be understood that the Examples, while indicating certain embodiments, are given by way of illustration only. From the above discussion and the Examples, one skilled in the art can ascertain essential characteristics of this disclosure, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt to various uses and conditions.
As used herein, “Comp. Ex.” means Comparative Example; “Ex.” means Example; “No.” means number; “%” means percent or percentage; “wt %” means weight percent; “IV” means intrinsic viscosity; “dL/g” is deciliters per gram; “g” is gram(s); “mg” is millligram(s); “° C.” means degrees Celsius; “° F.” means degrees Fahrenheit; “temp” means temperature; “min” is minute(s); “h” is hour(s); “sec” is second(s); “Ib” is pound(s); “kg” is kilogram(s); “mm” is millimeter(s); “m” is meter(s); “gpl” is grams per liter; “m/min” is meters per minute; “mol” is mole; “kg” is kilogram(s); “ppm” is parts per million; “wt” is weight; “dpf” is denier per filament; “gpd” or “g/d” is grams per denier; “dtex” means decitex; “dN/tex” means “deciNewton(s) per tex; “mL” means milliliter(s); “IV” means intrinsic viscosity;
Unless otherwise noted, all materials were used as received.

Measurement of Crimp Contraction After Heating CCa)—Crimp Contraction Method

Crimp contraction after heating (Cca) values were determined according to the method described herein. The fiber of each Example and Comparative Example was independently formed into a skein of about 5000 +/−5 total denier (5550 dtex) with a skein reel at a tension of about 0.1 gpd (0.09 dN/tex). The skein was then halved in length by folding the skein in two in order to accommodate the interior of the oven used for heatsetting. The folded skein was hung at its mid-section from a hook and was conditioned at 70 +/−1° F. (21 +/−1 ° C.) and 65 +/−2% relative humidity for a minimum of 16 hours. The folded skein was then hung substantially vertically on a rack from a hook at its mid-section and a 1.5 mg/den (1.35 mg/dtex) weight was hung through the two loops of the folded skein at the bottom of the skein. The weighted skein was then heated in an oven for 5 min at 250° F. (121° C.) after which the rack and skein were removed and allowed to cool for 5 minutes, then allowed conditioned at 70° F. +/−1° F. (21 +/−1° C.) and 65% +/−2% relative humidity for a minimum of 2 hours with the 1.5 mg/denier weight left on the skein for the remainder of the test. The length of the skein was measured to within 1 mm and recorded as “Ca”. Next, a 1000 g weight was hung from the bottom of the skein, allowed to reach equilibrium and the length of the skein measured within 1 mm and recorded as “La”. Crimp contraction after heating “CCa” value (%) was calculated according to the formula:
% CCa=100×(La−Ca)/La

Determination of Intrinsic Viscosity

The intrinsic viscosity (IV) was determined using a Viscoteck Y 501C Forced Flow Viscometer (Malvern Corporation, Houston Tex., USA). A 0.15 gram sample was weighed into a 40 mL glass vial containing 30 mL solvent (phenol/1,1,2,2-Tetrachloroethane (60/40 weight percent)) and a stir bar. Sample was then placed into 100° C. preheated heat block, heated and stirred for 30 minutes, removed from the block and cooled for 30-45 minutes before placing into the auto sampler rack of the viscometer. Samples were then analyzed by ASTM method D5225-92 (Standard Test Method for Measuring Solution
Viscosity of Polymer With A Differential Viscometer).

Polymer Preparation

Two grades of PTT homopolymer pellets were obtained from E. I du Pont de Nemours and Company, Wilmington, Delaware USA. One grade had an IV of 1.02 dL/g, a second grade had an IV of 0.96 dL/g. PET homopolymer pellets were obtained from Sinopec Shanghai Petrochemical Company, Ltd. Shanghai, PRC and had an IV of 0.50 dl/g. PET homopolymer pellets were obtained from DuPont Crystar® and had an IV of 0.64 dl/g. Co-PET copolymer (containing 1.9 mole % isophthalic acid) pellets with an IV of 0.82 dl/g was obtained from NanYa
Plastics Corporation, Livingston N.J., USA.
Polymer blend compositions were made from a physical blend of the 0.96 IV PTT pellets and the 0.82 IV PET copolymer pellets prior to extrusion (“salt and pepper” (S&P) blend). These pellet blends were intimately mixed during the extrusion process during spinning. Alternatively, in some Examples the PTT and PET copolymer pellets were compounded with a twin screw extruder, pelletized and used directly during spinning without the need to make a salt and pepper blend.
In preparation for melt spinning, the pellets were dried under nitrogen in a vacuum oven for 15 hours at 25 inches mercury vacuum and a temperature of 120° C. The dried pellets were transferred directly to the nitrogen-purged feed hopper of the spinning machine.

Fiber Preparation

The two components of a bicomponent fiber were melt spun using processes and equipment generally applicable to spinning side-by-side and eccentric sheath/core bicomponent fibers, for example as disclosed in U.S. Pat. Nos. 6,641,916 B1, 6,803,102, and 7,615,173 B2, which are incorporated herein by reference.
In spinning the bicomponent fibers of the Examples, the polymers were melted in a pair of Werner & Pfleiderer co-rotating 28-mm twin screw extruders having 0.5-40 pound/hour (0.23-18.1 kg/hour) capacities. One extruder, referred to herein as the East extruder, was used to melt the PET homopolymer (0.50 and 0.64 IV) pellets and a second extruder, referred to herein as the West extruder, was used to melt 1) PTT pellets alone 2) salt-and-pepper (“S&P”) blends of PTT pellets and co-PET copolymer pellets, or 3) compounded PTT/co-PET pellets. The temperatures of the West extruder, spinning block and East extruder are cited in the Examples. Each extruder fed the spinning block containing a recessed spinneret. The spinneret used was a post-coalescence, side by side, bicomponent spinneret having thirty-four pairs of capillaries arranged in a circle, an internal angle between each pair of capillaries of 30 degrees, a capillary diameter of 0.64 mm, and a capillary length of 4.24 mm. The bicomponent filaments exiting the spinneret were subjected to cooling by cross-flow quench air nominally at 20° C. and 0.5 mm/sec face velocity. The filaments were then advanced to dual feed rolls operating at about 800-1200 meters/minute, depending on the draw ratio. Between the spinneret and feed rolls, a finish applicator was used to apply lubricant to the filament bundle. The feed rolls were typically heated to 70° C. in order to affect draw. The filament bundle was then accelerated to the anneal rolls operating at speeds of about 3000-3600 m/min, depending on the desired draw ratio, and the anneal roll temperature was typically 170° C. The annealed bicomponent fiber was then advanced to two sets of dual letdown rolls operating at room temperature, before being wound on a Barmag SW6 600 winder. The fibers had snowman (oblong) cross-sectional shape.

Example 1

Variation of PTT Intrinsic Viscosity (IV)

Example 1 illustrates the use of PTT pellets with different IV's to produce bicomponent fibers having desirable crimp contraction after heating (CCa) values. The IV of the PTT pellet used to make the fiber was either 1.25 dl/g (1a) or 1.02 dl/g (1b). The IV of the PET pellet was 0.64 dl/g in both cases. For each
Example, the weight ratio of PTT to PET was 50/50. Example 1-a was 115 denier 34 filament fiber. Example 1-b was 75 denier 34 filament fiber.

TABLE 1

Process Conditions and Crimp Contraction for Examples 1a and 1b

		West/
	PTT/PET	block/East	Feed roll	Anneal roll	Letdown roll	Winder
	pellet IV,	Temperature,	speed, m/min	speed, m/min	speeds, m/min	speed,	CCa,
Ex. No.	dL/g	° C.	and temp, ° C.	and temp	at room temp	m/min	%

1-a	1.25/0.64	270/270/270	1106	3540@160° C.	3550/3500	3500	21.2
1-b	1.02/0.64	260/270/275	937	3000@140° C.	3000/2950	2950	8.8

Example 2

Variation of PTT/PET Weight Ratio

Example 2 illustrates how changing the weight ratio of the PTT and PET components in the bicomponent fiber changes the crimp contraction after heating (CCa). The bicomponent fibers were 75 denier with 34 filaments. In Table 2, Comparative Examples A, B, and C demonstrate high levels of CCa, that is, above 30%, and are more suited to apparel products where stretch and recovery are desired. Examples 2a, 2b, and 2c illustrate process conditions resulting in high bulk bicomponent fibers having crimp contraction after heating of 30% or less, which are suited for making carpet. Winder speed was 3495 m/min for Comparative Example A and 3500 m/min for Comparative Examples B and C, and Examples 2a, 2b, and 2c.

TABLE 2

Process Conditions and Crimp Contraction for Comparative
Examples A, B, and C, and Examples 2a, 2b, and 2c

	PTT/PET	PTT/PET	West/	Feed roll	Anneal roll	Letdown roll
Ex.	pellet IV,	weight	block/east	speed*,	speed**,	speeds**,	Cca,
No.	dL/g	ratio	Temp, ° C.	m/min	m/min	m/min	%

Comp.	0.96/0.50	50/50	255/255/270	996	3550	3550/3550	61.8
Ex. A
Comp.	0.96/0.50	40/60	260/265/270	969	3550	3550/3540	39.3
Ex. B
Comp.	0.96/0.50	35/65	260/265/270	1100	3600	3530/3525	34.1
Ex. C
2-a	0.96/0.50	30/70	260/265/270	1088	3560	3530/3525	27.1
2-b	0.96/0.50	25/75	260/265/270	1085	3550	3530/3525	21
2-c	0.96/0.50	20/80	260/265/270	1085	3550	3530/3525	2.3

Notes:
*at 70° C.
**at room temperature

Example 3

Variation of Weight Ratio Between the Two Components with Fixed PTT/co-PET Blend as One Component

Table 3 illustrates how one component of the bicomponent was made with a 50/50 blend of PTT and co-PET and the second component was made from PET. In Examples 3a-e, a 50/50 weight percent “salt and pepper” blend of 0.96 IV dl/g PTT pellets and 0.82 IV dl/g co-PET pellets were mixed together until the pellets were randomly dispersed. After drying, the pellet mixture was fed into the West Extruder. The East Extruder was fed dried 0.50 IV PET homopolymer pellets. Bicomponent fibers were then made with the first component comprising a 50/50 weight blend of PTT/co-PET as described above, and the second component was PET, wherein the weight ratio between the two components was varied. For instance, Example 3a was made with a 70/30 weight ratio between the first component (i.e. 50/50 PTT/co-PET blend) and the second component (i.e. PET). In the remaining examples in Table 3, the polymer remained the same and only the weight ratio between the two components was changed. Winder speed was 3500 m/min for all of these Examples.

TABLE 3

Example 3 Process Conditions and Crimp Contraction Obtained

	Weight Ratio	West/	Feed roll	Anneal roll	Letdown roll
Ex.	of PTT/co-PET	Block/East	speed,	speed,	speeds,	Cca,
No.	Blend and PET	Temp., ° C.	m/min	m/min	m/min	%

3-a	70/30	265/265/270	1196	3560	3535/3530	28
3-b	60/40	265/265/270	1196	3560	3535/3530	27.9
3-c	50/50	265/265/270	1196	3560	3535/3530	26.9
3-d	40/60	265/265/270	1196	3560	3535/3530	24.5
3-e	30/70	265/265/270	1196	3560	3530/3535	3.3

Example 4

Variation of PTT/co-PET Blend Ratio in One Component with Fixed Weight Ratio Between the Two Components

Table 4 illustrates how one component of the bicomponent was made with blends of PTT and co-PET and the second component was made from PET. In contrast to Table 3, the examples shown in Table 4 show the effect of changing blend ratio of PTT to co-PET within the first component while keeping a constant 50/50 weight ratio between the two components. In Table 4, Examples 4a-4d and 4f-4g, and Comparative Example D, were made by varying the pellet ratio in a “salt and pepper blend” (“S&P”) of 0.96 IV dl/g PTT and 0.82 IV dl/g co-PET. Pellets were mixed together until the randomly dispersed. After drying, the pellet mixture was fed into the West Extruder. The East Extruder was fed dried 0.50 IV
PET homopolymer pellets. Bicomponent fibers were then made with the first component comprising a blend of PTT/co-PET as described above, and the second member was comprised of PET, wherein the weight ratio between the two members was fixed at 50/50. For instance, in Example 4a the first component of the bicomponent was made from a 10/90 blend ratio of PTT/co-PET and the second component of the bicomponent was made with PET. The weight ratio between the two components was 50/50. In Example 4-e, the PTT and co-PET pellets were pre-compounded in a twin screw extruder, quenched, pelletized and re-dried before use. This is in contrast to Examples 4d wherein the component was made from a salt and pepper blend. It should also be noted that
Comparative Example D contains a higher crimp contraction after heating value, % CCa=43.1, which is more suited to the high stretch levels of apparel fabrics.
For Example 4-a the winder speed was 3475 m/min; for Examples 4-b, 4-c, 4-d, 4-e, 4-f, 4-g, and Comparative Example D the winder speed was 3500 m/min.

TABLE 4

Process Conditions and Crimp Contraction for Examples 4a-4g and Comparative Example D

		Weight Ratio	West/	Feed roll	Anneal roll	Letdown roll
Ex.	Blend Prep.	of PTT and	Block/East	speed,	speed,	speeds,	Cca,
No.	Method	coPET in Blend	Temp, ° C.	m/min	m/min	m/min	%

4-a	S&P	10/90	275/275/270	1120	3540	3525/3520	23.7
4-b	S&P	30/70	275/275/270	1185	3525	3510/3505	22.4
4-c	S&P	40/60	275/275/270	1185	3525	3510/3505	16.1
4-d	S&P	50/50	275/275/270	1186	3560	3535/3530	22.1
4-e	compounded	50/50	265/265/270	1186	3560	3535/3530	21.6
4-f	S&P	60/40	265/265/270	1186	3560	3535/3530	11.2
4-g	S&P	70/30	265/265/270	1186	3560	3535/3530	24.5
Comp.	S&P	90/10	265/265/270	1186	3560	3535/3530	43.1
Ex. D

Example 5

Carpet Production using a Self-Bulking Bicomponent Fiber As in Example 2a

Carpets comprising a self-bulking bicomponent fiber can be spun at a 1200 denier-120 filament (10 dpf) using the polymers, polymer IV, and fiber weight ratio described in Example 2a above. These bicomponent fibers would have higher denier and number of filaments than in Example 2a. The spinning speeds will be adjusted (i.e. draw ratio) so that the resulting fiber has a crimp contraction after heating of 30% or less. The bicomponent fiber thus made can then be plied on standard twisting equipment with a second bicomponent fiber of the same type. After twisting, the fiber can processed by Superba® heat setting equipment that will fully develop the bicomponent fiber crimp and set the twist in the plied yarn. The heat set bicomponent yarn can then be tufted into a nonwoven polypropylene backing on a standard carpet tufting machine, with other heat set yarns of the same composition to yield a tufted fabric comprised entirely of heat set, plied bicomponent yarns. The tufted fabric can then be processed on standard processing equipment used by the carpet industry to apply a latex formulation to the back of the carpet that locks the tufted face fiber into a woven carpet backing. A secondary backing would then be applied to protect the underside of the carpet. The greige (undried) carpet can then be processed on standard continuous dye equipment and then dried in continuous ovens to remove moisture. The finished carpet is then rolled onto a large tube for installation on-site.

Example 6

Carpet Production using a Self-Bulking Bicomponent Fiber As in Example 2a but with Trilobal Cross-Sectional Shape

Carpets comprising a self-bulking bicomponent fiber can be spun at a 1200 denier-120 filament (10 dpf) using the polymers, polymer IV, and fiber weight ratio described in Example 2a above. The spinneret orifice is chosen to make a side by side trilobal cross section, although any other cross-sectional shape useful for carpet manufacture can be selected. These bicomponent fibers would have higher denier and number of filaments than in Example 2a and a trilobal cross-sectional shape. The spinning speeds will be adjusted (i.e. draw ratio) so that the resulting fiber has a crimp contraction after heating of 30% or less. The bicomponent fiber thus made can then be plied on standard twisting equipment with a second bicomponent fiber of the same type. After twisting, the fiber can processed by Superba® heat setting equipment that will fully develop the bicomponent fiber crimp and set the twist in the plied yarn. The heat set bicomponent yarn can then be tufted into a nonwoven polypropylene backing on a standard carpet tufting machine, with other heat set yarns of the same composition to yield a tufted fabric comprised entirely of heat set, plied bicomponent yarns. The tufted fabric can then be processed on standard processing equipment used by the carpet industry to apply a latex formulation to the back of the carpet that locks the tufted face fiber into a woven carpet backing. A secondary backing would then be applied to protect the underside of the carpet. The greige (undried) carpet can then be processed on standard continuous dye equipment and then dried in continuous ovens to remove moisture. The finished carpet is then rolled onto a large tube for installation on-site.

Claims

What is claimed is:

1. A carpet whose face fiber comprises a bicomponent fiber comprising one component of poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer and a second component of poly(trimethylene terephthalate) or a blend of poly(trimethylene terephthalate) with poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, wherein the bicomponent fiber is self-bulking due to differential shrinkage, in contrast to carpet whose face fiber is made from bulk continuous homofilament that is mechanically bulked.

2. The carpet of claim 1, wherein the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath core configuration.

3. The carpet of claim 1 or claim 2, wherein the first and second components of the bicomponent fiber are present in a weight ratio ranging from 80:20 to 20:80.

4. The carpet of claim 1 or claim 2, wherein the crimp contraction after heating of the bicomponent fiber is equal to or less than 30% as determined according to the Crimp Contraction Method.

5. The carpet of claim 3, wherein the crimp contraction after heating of the bicomponent fiber is equal to or less that 30% as determined according to the Crimp Contraction Method.

6. The carpet of claim 1, wherein the face fiber further comprises at least one additional fiber selected from bulked continuous filament, synthetic staple fiber, and natural fiber.

7. The carpet of claim 6, wherein the at least one additional fiber is bulked continuous filament, and the bulked continuous filament comprises nylon, polypropylene, or polyester.

8. The carpet of claim 6, wherein the at least one additional fiber is synthetic staple fiber, and the synthetic staple fiber comprises nylon or polyester.

9. The carpet of claim 6, wherein the at least one additional fiber is natural fiber, and the natural fiber comprises wool, silk, or cotton.

10. An improved process for making a yarn to produce a carpet whose face fiber comprises a self-bulking bicomponent fiber comprising one component of poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer and a second component of poly(trimethylene terephthalate) or a blend of poly(trimethylene terephthalate) with poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, said process comprising:

a) extruding the two components on a spinning machine capable of producing two or more independent melt streams;

b) combining the melt streams in a spinneret suited for making bicomponent fibers;

c) quenching in air the self-bulking bicomponent fibers produced in step (b);

d) drawing and heat setting the self-bulking bicomponent fibers; and

e) winding up the self-bulking bicomponent fibers by suitable means for subsequent processing into carpet, wherein the self-bulking bicomponent fibers eliminate the need for a mechanical bulking step.

11. The improved process of claim 10, wherein the bicomponent fiber can be in a side-by-side configuration or an eccentric sheath core configuration.

12. The improved process of claim 10 or 11, wherein the first and second components of the bicomponent fiber are present in a weight ratio ranging from 80:20 to 20:80.

13. The improved process of claim 10 or claim 11, wherein the crimp contraction after heating of the bicomponent fiber is equal to or less that 30% as determined according to the Crimp Contraction Method.

14. The improved process of claim 12, wherein the crimp contraction after heating of the bicomponent fiber is equal to or less that 30% as determined according to the Crimp Contraction Method.