JP7730815B2 - Carpets made from bicomponent fibers containing self-bulking PTT - Google Patents

Description

The present disclosure relates to carpets, and more particularly to carpets whose surface fibers comprise bicomponent fibers containing self-bulking poly(trimethylene terephthalate) (PTT).

In modern carpet manufacturing, it is common to use synthetic polymers (e.g., nylon, polyester, polypropylene) to create fibers with a high level of bulk, which can be defined as an enhanced fiber coverage or apparent volume compared to unbulked or "flat" fibers. These bulked continuous fibers ("BCF") are typically monocomponent fibers produced in a spinning machine equipped with high-temperature/high-pressure jets and cooling drums specifically designed to mechanically bulk the fibers. This process has several drawbacks. The high temperature, high pressure, and turbulent airflow of the fibers within the jet can damage the fiber filaments and adversely affect the fiber's physical properties. Furthermore, the need to impart bulk through the jet/drum process necessitates reduced fiber production rates compared to other spinning processes that do not require mechanical bulking, i.e., fully oriented yarn ("FDY") or partially oriented yarn ("POY") flat yarns.

One way to characterize textile fibers is by the amount of crimp in the fiber. "Crim" refers to the undulations of the fiber and can be expressed as a count per unit length. The amount of crimp, also referred to herein as "crimp shrinkage," can be expressed by comparing the extended length of a fiber under load to the contracted length of an unloaded fiber. The amount of crimp in a fiber can be natural (e.g., wool) or imparted to synthetic fibers during manufacturing to suit the desired end use. Crimp can be induced by using air and heat in a bulking jet (BCF), twisting/untwisting POY into draw-textured yarn (DTY) in a false twister, or by differential shrinkage in side-by-side or eccentric sheath/core bicomponent fibers. Low crimp corresponds to textile fibers with increased loft or bulk and is desirable when fabric opacity or covering power is important. Instead, high crimp results in fibers with significant levels of stretch and recovery, which are valuable in apparel applications.

In carpet applications, a low crimp is desirable to provide bulk without significantly developing stretch. Self-crimping bulky yarns containing bicomponent filaments for fabrics are described in U.S. Patent No. 5,629,999. In apparel fabrics, the crimp properties of side-by-side and eccentric sheath/core bicomponent fibers are typically maximized to provide high levels of stretch to the fibers and resulting fabrics. U.S. Patent No. 5,629,999, issued October 12, 2004 to Talley et al., exemplifies the production of bicomponent fibers with asymmetric fiber cross sections and is incorporated herein in its entirety.

U.S. Patent No. 6,299,949, issued to Talley et al. on December 12, 2000, discloses self-setting yarns made from bicomponent fibers that form helical crimps that lock in twist and create bulk. The use of such yarns in carpets and textiles is also disclosed. Various 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. Patent No. 4,629,999 to Howell et al., U.S. Patent No. 5,629,999 to Roark et al., and U.S. Patent No. 6,629,999 to Chuah; U.S. Patent No. 6,629,999 to Scott et al.; Non-Patent Document 1; and Non-Patent Document 2 describe carpets made of poly(trimethylene terephthalate) (PTT) homofiber but not bicomponent fiber, all of which are incorporated herein by reference.

Disclosed herein is a carpet in which the face fibers of the carpet comprise bicomponent fibers including a first 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), and the bicomponent fibers are self-bulking due to differential shrinkage, in contrast to carpets in which the face fibers of the carpet are made from bulk continuous homofilaments that have been mechanically bulked.

U.S. Patent No. 7,790,282 U.S. Patent No. 6,803,102 B1 U.S. Patent No. 6,158,204 U.S. Pat. No. 5,645,782 U.S. Patent No. 6,109,015 U.S. Patent No. 6,113,825 International Publication No. 99/19557

H. Modlich, “Experience with Polyesters Fibers in Tufted Articles of Heat-Set Yarns, Chemiefasern/Textilind. 41/93, 786-94 (1991) 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)

In a first embodiment, disclosed herein is a carpet whose face fibers comprise bicomponent fibers including a first 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 fibers are self-bulking due to differential shrinkage, in contrast to carpets whose face fibers are made from mechanically bulked bulk continuous homofilaments.

In a second embodiment, the bicomponent fibers may 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 post-heat crimp shrinkage percentage of 30% or less, as determined according to the crimp shrinkage method disclosed herein.

In a fifth embodiment, there is provided an improved process for making yarn to produce carpets in which the face fibers of the carpet comprise self-bulking bicomponent fibers comprising a first 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 in a spinner capable of producing two or more independent melt streams;
b) combining the melt streams in a spinneret suitable for producing 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 the self-bulking bicomponent fibers by means suitable for subsequent processing into a carpet,
A process is disclosed in which the self-bulking bicomponent fibers do not require a mechanical bulking step.

In a sixth embodiment, the bicomponent fibers may be in a side-by-side or 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 post-heat crimp shrinkage rate of 30% or less, as determined according to the crimp shrinkage method disclosed herein.

All cited patents, patent applications, and publications are incorporated herein by reference in their entirety.

As used herein, the terms "embodiment" or "disclosure" are not meant to be limiting and generally apply to any of the embodiments defined in the claims or described herein. These terms are used interchangeably herein.

A number of terms and abbreviations are used in this disclosure. The following definitions apply unless specifically stated otherwise.

The indefinite article "one" preceding an element or component is intended to be open-ended regarding the number of instances (i.e., occurrences) of that element or component. Thus, "one" and "the" should be read to include one or at least one, and the singular form of an element or component also includes the plural, unless the number is specifically implied to be singular.

The term "comprising" denotes the presence of the feature, integer, step, or component recited in the claim, but does not exclude 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, if a range of "1 to 5" is recited, the recited range should be interpreted as including "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," etc.

When used herein in connection with a numerical value, the term "about" refers to a range of ±0.5 of that numerical value, unless the term is otherwise specifically defined in the context. For example, the phrase "a pH value of about 6" refers to a pH value of 5.5 to 6.5, unless the pH value is otherwise specifically defined.

Every numerical upper limit given throughout this specification is intended to include every lower numerical limit, as if such lower numerical limits were expressly written herein. Every numerical lower limit given throughout this specification will include every higher numerical limit, as if such higher numerical limits 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.

As used herein, the term "bicomponent fiber" refers to a fiber made of two different polymer components composed of different polymer types, the same polymer type but with different intrinsic viscosities, or a blend of two or more polymers, extruded from the same spinneret with both polymers in the same filament. Bicomponent fibers may also be referred to as composite fibers, and the terms may 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.

As used herein, the term "carpet" refers to a floor covering made of pile yarns or fibers and a backing system. It may be tufted carpet or woven. As used herein, the term "carpet" includes wall-to-wall carpet, carpet tile, rugs, vehicle and building entrance mats, such as those designed to trap dirt underfoot.

The term "face" refers to the side of the carpet containing the tufted or woven yarns.

As used herein, the term "surface fibers" refers to the fiber content of the carpet, including those visible to the observer. Surface fibers are primarily made up of yarns, and these yarns can be cut, looped, cut-and-loop, or any number of types known to those skilled in the art.

The term "copolymer" refers to a polymer composed of a combination of multiple types of monomers. Copolymers can form the basis for several types of 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 yarns.

The term "crimp shrinkage" is a measure of fiber crimp and refers to the contraction of yarn length from a fully extended state (i.e., a state in which the filaments are substantially straightened). This is due to the formation of crimps in individual filaments under specific conditions of crimp development. It is expressed as a percentage of the extended length. Crimp shrinkage can be measured before and/or after treating the fiber to partially or fully develop crimp, for example, by heating; typically, the post-heat crimp shrinkage is more interesting and informative because it includes crimps generated by heating. Unless otherwise specified, crimp shrinkage values disclosed herein are post-heat crimp shrinkage values (Cca).

The term "denier" is a measure of the weight per unit length of any linear material.

The term "fiber" refers to a unit of material, either natural or synthetic, that forms the basic element of fabrics and other woven structures. It is characterized by having a length at least 1000 times its diameter or width. Typically, a textile fiber is a unit that can be spun into yarn or made into fabric by a variety of processes, including weaving, knitting, braiding, felting, and twisting. Fibers are characterized by their denier (weight in grams per 9000 meters of fiber) and the number of filaments they contain.

"Filament" refers to a thin thread or continuous strand of fiber. There are two types of filaments: monofilament and multifilament. Filaments are characterized by their denier per filament ("dpf").

"Monofilament" means a filament made of one polymer type.

"Staple" refers to either natural fibers or cut lengths from filaments.

The term "intrinsic viscosity" ("IV") refers to the ratio of the specific viscosity of a solution of known concentration to the solute concentration extrapolated to zero concentration.

The term "tufting" refers to the process of creating woven fabrics, such as carpets, on specialized multi-needle machines. "Tufts" are loose threads drawn into the fabric and protruding from the surface in the form of cut threads or loops. The cut or uncut loops form the surface of a tufted or woven carpet.

The term "yarn" refers to a collection of individual filaments, either alone or twisted together with another collection of filaments. The terms "fiber" and "yarn" are used interchangeably herein.

The term "quenching" refers to rapid, sudden cooling in water, oil, or air to achieve specific physical properties or material characteristics.

The term "poly(ethylene terephthalate)" or PET refers to a polymer derived substantially exclusively from ethylene glycol and terephthalic acid (or an 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 a polymer comprising repeat units derived from ethylene glycol and terephthalic acid (or an equivalent), and further containing at least one additional unit derived from an additional monomer, such as isophthalic acid (IPA) or cyclohexanedimethanol (CHDM). Poly(ethylene terephthalate) copolymers can contain from about 1 mol % to about 30 mol % of the additional monomer, for example, from about 1 mol % to about 15 mol % of the additional monomer.

The term "poly(butylene terephthalate)" or PBT refers to a polymer derived substantially exclusively from 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 a polymer that includes repeat units derived from 1,4-butanediol and terephthalic acid and also contains at least one additional unit derived from an additional monomer, such as a comonomer for the PTT copolymer disclosed herein.

The term "poly(trimethylene terephthalate)" or PTT refers to a polyester produced by polymerizing 1,3-propanediol and terephthalic acid. PTT 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" refers to a polymer of essentially only 1,3-propanediol and terephthalic acid (or equivalent). The term "poly(trimethylene terephthalate)" also includes PTT copolymers, thereby meaning a polymer containing repeat units derived from 1,3-propanediol and terephthalic acid (or equivalent) and at least one additional unit derived from an additional monomer. Examples of PTT copolymers include copolyesters produced using three or more reactants, each of which has two ester-forming groups. For example, copoly(trimethylene terephthalate) is a copolyester in which the comonomers used to produce the copolyester are linear, cyclic, and branched aliphatic dicarboxylic acids having 4 to 12 carbon atoms (e.g., butanedioic acid, pentanedioic acid, hexanedioic acid, dodecanedioic acid, and 1,4-cyclohexanedicarboxylic acid); aromatic dicarboxylic acids having 8 to 12 carbon atoms other than terephthalic acid (e.g., isophthalic acid and 2,6-naphthalenedicarboxylic acid); linear, cyclic, and branched aliphatic diols having 2 to 8 carbon atoms (e.g., ethane diols other than 1,3-propanediol); Comonomers can be used when selected from the group consisting of diols, 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 to 10 carbon atoms (e.g., hydroquinone bis(2-hydroxyethyl) ether, or poly(ethylene ether) glycols having a molecular weight of less than about 460, including diethylene ether glycol). The comonomer is typically present in the copolyester in a concentration ranging from about 0.5 mol % to about 15 mol %, and can be present in amounts up to about 30 mol %.

The term "Triexta" refers to the generic name for the subclass of polyester, PTT. "Triexta" and "PTT" can be used interchangeably herein.

Poly(trimethylene terephthalate) typically has an intrinsic viscosity of about 0.5 deciliters per gram (dl/g) or greater and typically about 2 dl/g or less. Poly(trimethylene terephthalate) preferably has an intrinsic viscosity of about 0.7 dl/g or greater, more preferably 0.8 dl/g or greater, and even more preferably 0.9 dl/g or greater, and typically has an intrinsic viscosity of about 1.5 dl/g or less, preferably 1.4 dl/g or less, with currently available commercial products having an intrinsic viscosity of 1.2 dl/g or less. Poly(trimethylene terephthalate) is commercially available under the trademark Sorona® from E. I. du Pont de Nemours and Company, Wilmington, DE.

Carpets made from poly(trimethylene terephthalate) homofiber and their manufacture, as well as fiber and fibre manufacture, are described in U.S. Patent No. 5,645,782 to Howell et al., U.S. Patent No. 6,109,015 to Roark et al., and U.S. Patent No. 6,113,825 to Chuah; U.S. Patent Nos. 6,740,276, 6,576,340, and 6,723,799; WO 99/19557 to 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 generally preferred for carpets.

Typically, PTT-containing bicomponent fibers are used in the manufacture of fabrics and apparel that have durable stretch properties. In contrast, such stretch properties are not necessary in carpet manufacturing. Rather, fibers used in carpet manufacturing are usually mechanically bulked to provide high levels of bulk; such fibers are commonly referred to as "BCF" fibers.

Disclosed herein is a carpet in which the face fibers of the carpet comprise bicomponent fibers including a first 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 and PET homopolymer or PET copolymer (co-PET), and in which the bicomponent fibers are self-bulking due to differential shrinkage, in contrast to carpets in which the face fibers of the carpet are made from bulk continuous homofilaments that have been mechanically bulked.

1. An improved process for making yarn to produce carpets in which the face fibers of the carpet comprise self-bulking continuous fibers comprising a first component of poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET) and a second component of poly(trimethylene terephthalate) (PTT) homopolymer or a blend of PTT with PET homopolymer or PET copolymer (co-PET), said process comprising:
a) extruding the two components in a spinner capable of producing two or more independent melt streams;
b) combining the melt streams in a spinneret suitable for producing 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 the self-bulking bicomponent fibers by means suitable for subsequent processing into a carpet,
Also disclosed is a process in which the self-bulking bicomponent fibers do not require a mechanical bulking step.

The bicomponent fibers described herein may be in a side-by-side ("S/S") configuration or an eccentric sheath/core ("S/C") configuration. Bicomponent fibers can be formed into various cross-sectional shapes, such as round, delta, triangular, scalloped, or other shapes, by using specific spinnerets for each shape, such as those disclosed in U.S. Pat. No. 6,803,102, the entire contents of which are incorporated herein by reference.

Typically, carpet fibers are homofilament fibers that undergo a mechanical bulking step during the manufacturing process. In contrast, the carpet described herein, in which the face fibers of the carpet comprise self-bulking continuous fibers, including bicomponent fibers containing poly(trimethylene) terephthalate, is self-bulking due to differential shrinkage.

As mentioned above, one component of a self-bulking bicomponent fiber is PTT or a blend of PTT with PET or co-PET. Compared to other commercially available polyesters, PTT can be very effective at providing crimp due to its unique shrinkage properties. The other component of a self-bulking bicomponent fiber is PET or co-PET, which has minimal shrinkage compared to PTT, so this combination of components maximizes the shrinkage differential and develops crimp. In contrast, PBT, PTT, and PTT/PET blends shrink significantly, resulting in less crimp in the resulting bicomponent fiber due to the smaller shrinkage differential between the two components. Therefore, poly(butylene terephthalate) (PBT) is a less preferred component for use with PTT or PTT/PET blends to create self-bulking bicomponent fibers. For example, at equal polymer weight ratios in side-by-side or eccentric sheath/core self-bulking bicomponent fibers, a bicomponent fiber containing PTT and PET will provide more bulk than a bicomponent fiber containing PBT and PET, or a bicomponent fiber containing two different PETs, each with a different intrinsic viscosity (IV).

Nylon polymers, including nylon 6 and nylon 66, are sometimes used as the first component in self-bulking bicomponent fibers; however, nylon polymers generally do not bond well with polyester as the second component, and can crack or crump under stress. For this reason, bicomponent fibers containing nylon and polyester may not be the best choice for carpet yarns.

The two components, PET or co-PET, and PTT or a blend of PTT with PET or co-PET, 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 component to the second component 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 component to the second component is approximately 50:50.

For use in carpets, self-bulking bicomponent fibers have a post-heat crimp shrinkage value of 30% or less. Post-heat crimp shrinkage can be measured using the crimp shrinkage measurement method disclosed in the Examples section below. There are several ways in which the two components of a bicomponent fiber can be adjusted to achieve a desired post-heat crimp shrinkage 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 example, if the IV difference between the two components of a bicomponent fiber is too great, a high level of shrinkage differential can occur between the two components, resulting in high crimp values and fiber stretch properties that are unsuitable for carpet manufacturing. In contrast, if the IV difference between the two components is too small, there will be no significant difference in shrinkage between the two components, resulting in little bulk.

Another way to produce bicomponent fibers with the desired crimp level is to vary the weight ratio of the two components. If the bicomponent fiber contains a significant proportion of PTT, the resulting fiber can have a high crimp value and fiber stretch. Conversely, a very small volumetric amount of PTT may not provide enough post-heat bulk or crimp shrinkage to achieve the desired level.

A third method for producing bicomponent fibers with a desired crimp level is to employ a PET/PTT blend in a fixed ratio (e.g., a 50/50 weight ratio of PTT to PET) as the first component and PET as the second component. It has been found that blending PET and PTT in a single component can be used to modify the high shrinkage characteristics of PTT alone. When a bicomponent fiber is produced with the first component comprising a blend of PTT and PET and the second component being PET, it is possible to produce fibers with equal weight ratios (e.g., 50/50 w/w component 1:component 2) that provide the desired crimp level, i.e., crimp shrinkage after heating of 30% or less. In some spinneret designs, it may be desirable to produce bicomponent fibers with approximately equal weight ratios of the two components, and blending PET with PTT is one way to achieve this result.

Alternatively, useful bicomponent fibers disclosed herein can be made by varying the composition of the PTT/PET blend in the first component of a bicomponent fiber, where the second component is PET or co-PET. This approach can be used to create useful bicomponent fibers where high levels of PET are desired. In summary, varying the polymer type, IV, weight ratio, and blend composition are all techniques by which self-bulking bicomponent fibers can be engineered to achieve a target crimp value that will yield the desired carpet bulk. Varying the relative speeds of the rolls and/or winder during fiber production can also affect crimp shrinkage.

One advantage of PTT in the self-bulking bicomponent fibers disclosed herein is that it provides a higher level of shrinkage compared to PET. Relatively small amounts of PTT can be used as the first component of a self-bulking bicomponent fiber to produce a bicomponent fiber with the desired bulk. However, too much PTT in the bicomponent fiber may result in a level of stretch that is too high for use in carpet yarns, making it more suitable for apparel applications.

Various additives may be added to either polymer or to both polymers. Additives include, but are not limited to, lubricants, nucleating agents, antioxidants, UV stabilizers, pigments, dyes, antistatic agents, soil and stain resistant agents, antimicrobial agents, and flame retardants.

For carpet applications, the self-bulking bicomponent fibers disclosed herein may have a denier ranging from about 300 to about 1400 grams per denier. Useful deniers per filament may range from about 2 to about 20.

In one embodiment of the carpet, the face fibers comprise bicomponent fibers including a first component of PET homopolymer or co-PET and a second component of PTT or a blend of PTT and PET homopolymer or co-PET, the bicomponent fibers being self-bulking due to differential shrinkage, the first component comprising PTT having an intrinsic viscosity in the range of about 0.9 dL/g to about 1.25 dL/g, the second component comprising PET having an intrinsic viscosity of about 0.64 dL/g, and the weight ratio of the two components being about 50/50.

In another embodiment, the first component comprises PTT having an intrinsic viscosity in the range of about 0.9 dL/g to about 1.0 dL/g, 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, the first component comprises a 50/50 weight/weight blend of PTT and co-PET, where the PTT has an intrinsic viscosity in the range of about 0.9 dL/g to about 1.0 dL/g, 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 with 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, the first 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, the co-PET has an intrinsic viscosity in the range of about 0.75 dL/g to about 0.85 dL/g, the weight ratio of PTT to co-PET in the blend in the range of 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 produced by feeding the polymers into a spinneret in the desired volumetric 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. Patent No. 5,162,074 to Hills.

The self-bulking bicomponent fibers disclosed herein can be used in conjunction with all other types of fibers, both synthetic and natural, used to make carpets. Carpets can be made by machine or manual tufting, weaving, and hand-knotting. Examples include: 1) broadloom carpets (also known as wall-to-wall carpets) for residential and commercial use, where tufted carpet is made in long continuous lengths several meters wide; 2) carpet tiles made in squares of various sizes for ease of installation; 3) household rugs; and 4) mats for vehicle and building entrances designed to clean feet before entering.

Any method known in the art for preparing carpets from fibers can be used to prepare the carpets described herein. Typically, the self-bulking bicomponent fibers disclosed herein can be used in the same carpet manufacturing processes as other synthetic and natural fibers. The bicomponent fibers can be used by themselves (i.e., as "single" yarns) in carpet construction, or can be further plied with the same bicomponent fiber or other types of fibers (e.g., nylon, polypropylene, polyester) to increase denier. Optionally, single and plied fibers can be entangled with an air jet before plying, and can also be heat-set with a machine specially designed to heat-set the physical properties of single and tufted yarns. One example of a heat-setting machine suitable for this purpose is manufactured by Superba® (Muhouse, France). Whether or not the bicomponent fibers are optionally air-entangled, twisted, or heat-set, the fibers can then be tufted onto a standard nonwoven or woven backing sheet common in the carpet industry. The surface fiber loops of the tufted carpet may be cut to provide a cut-loop carpet. After tufting, adhesive is often applied to the backside of the carpet (i.e., the side opposite the surface fibers) to hold the tufts in place. An additional backing layer may also be added to the backside of the carpet. The adhesive layer may contain fillers or flame retardants, depending on the particular end use of the carpet. The carpet may then be dyed using standard processes common in the carpet manufacturing industry; alternatively, pigments may be added to the bicomponent fibers and/or to the companion fibers during fiber extrusion to impart color to the finished fabric. Additionally, the surface yarns may be treated with materials designed to impart fire resistance, antistatic properties, or stain and soil resistance. Finished carpets are often dried to remove any water left over from the dyeing process.

The manufacturing process described above is typical for broadloom tufted carpet. Variations on this process, which are well known in the industry, may be employed in the manufacture of rugs, carpet tiles, and vehicle mats.

One feature of the bicomponent fibers disclosed herein is the development of crimp and bulk by raising the fiber temperature to at least 75°C but less than 200°C. Bicomponent fibers are exposed to this temperature range during the standard course of carpet manufacturing, including optional heat-setting, dyeing, and drying steps. Alternatively, carpets can be bulked by a separate heat-setting step, or bicomponent fibers (single or plied) can be heat-treated to bulk them.

The surface fibers, including bicomponent fibers, may be of circular cross section or of a non-circular cross section, such as trilobal. The fibers preferably have a crimp shrinkage value after heating of 30% or less.

An advantage of the carpet disclosed herein is that because the bicomponent fibers are self-bulking due to differential shrinkage, the yarns used to make the carpet do not need to be mechanically bulked. In contrast, carpet yarns made from bulk continuous homofilaments do not have differential shrinkage and therefore require mechanical bulking. In other words, by using bicomponent fibers with differential shrinkage, carpets can be made without the step of mechanically bulking continuous homofilaments.

Optionally, carpets whose surface fibers comprise the self-bulking bicomponent fibers disclosed herein may further comprise at least one additional fiber. The at least one additional fiber may be twisted together with the self-bulking bicomponent fiber to increase the denier, for example, or the at least one additional fiber may be used as an additional carpet yarn when tufting the carpet. The at least one additional fiber may be selected from bulked continuous filaments (i.e., homofilaments), synthetic staple fibers, and natural fibers. In one embodiment, the at least one additional fiber is a bulked continuous filament, including nylon, polypropylene, or polyester. In another embodiment, the at least one additional fiber is a synthetic staple fiber, including nylon or polyester. In a further embodiment, the at least one additional fiber is a natural fiber, including wool, silk, or cotton.

Non-limiting examples of embodiments disclosed herein include:
1. A carpet comprising bicomponent fibers whose face fibers comprise a first 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) and poly(ethylene terephthalate) (PET) homopolymer or poly(ethylene terephthalate) copolymer (co-PET), wherein the bicomponent fibers are self-bulking due to differential shrinkage, in contrast to carpets whose face fibers are made from mechanically bulked bulk continuous homofilaments.
2. The carpet of embodiment 1, wherein the bicomponent fibers may 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 fibers are present in a weight ratio ranging from 80:20 to 20:80.
4. The carpet of embodiment 1, 2, or 3, wherein the bicomponent fibers have a post-heat crimp shrinkage of 30% or less as determined according to the crimp shrinkage method.
5. The carpet of embodiment 1, 2, 3 or 4, wherein the face fibers further comprise at least one additional fiber selected from bulked continuous filaments, synthetic staple fibers, and natural fibers.
6. The carpet of embodiment 5, wherein the at least one additional fiber is a bulked continuous filament, the bulked continuous filament comprising nylon, polypropylene, or polyester.
7. The carpet of embodiment 5, wherein the at least one additional fiber is a synthetic staple fiber, the synthetic staple fiber comprising nylon or polyester.
8. The carpet of embodiment 5, wherein the at least one additional fiber is a natural fiber, the natural fiber comprising wool, silk, or cotton.
9. An improved process for making yarn for producing carpet, wherein the face fibers of the carpet comprise self-bulking bicomponent fibers comprising a first 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) and poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, said process comprising:
a) extruding the two components in a spinner capable of producing two or more independent melt streams;
b) combining the melt streams in a spinneret suitable for producing 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 the self-bulking bicomponent fibers by means suitable for subsequent processing into a carpet,
An improved process is provided in which the self-bulking bicomponent fibers do not require a mechanical bulking step.
10. The improved process of Example 9, wherein the bicomponent fibers may 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 bicomponent fiber has a crimp shrinkage of 30% or less after heating as determined according to the Crimp Shrinkage Method.

The present disclosure is further defined in the following examples. It should be understood that the examples, while indicating specific embodiments, are provided for illustrative purposes only. From the above discussion and examples, one skilled in the art will be able to ascertain the essential features of the present disclosure and may make various changes and modifications to adapt it to various applications and conditions without departing from the spirit and scope of the present invention.

As used herein, "Comp. Ex." means comparative example, "Ex." means example, "No." means number; "%" means percent or percentage, "wt%" means percent by weight, "IV" means intrinsic viscosity, "dL/g" means deciliters per gram, "g" means grams, "mg" means milligrams, "°C" means degrees Celsius, "°F" means degrees Fahrenheit, "temp" means temperature, "min" means minutes, "h" means hours, "sec" means seconds, "lb" means pounds, and "kg" means pounds. "mm" is millimeter, "m" is meter, "gpl" is grams/liter, "m/min" is meters/minute, "mol" is mole, "kg" is kilogram, "ppm" is parts/million, "wt" is weight, "dpf" is denier/filament, "gpd" or "g/d" is grams/denier, "dtex" means decitex, "dN/tex" means deciNewtons/tex, "mL" means milliliter, and "IV" means intrinsic viscosity.

All materials were used as received unless otherwise noted.

Measurement of Crimp Shrinkage After Heating (% CCa) by Crimp Shrinkage Method: Crimp shrinkage after heating (Cca) values were determined according to the method described herein. Each example and comparative fiber was independently formed into a hank of approximately 5000 +/- 5 total denier (5550 dtex) using a hank reel at a tension of approximately 0.1 gpd (0.09 dN/tex). The hanks were then folded in half to fit inside the oven used for heat setting. The folded hanks were then draped over a hook at their midsection and conditioned for a minimum of 16 hours at 70 +/- 1°F (21 +/- 1°C) and 65 +/- 2% relative humidity. The folded skein was then hung approximately vertically from its mid-hook on a rack, and a 1.5 mg/denier (1.35 mg/dtex) weight was attached to the bottom of the skein via two loops in the folded skein. The weighted skein was then heated in a 250°F (121°C) oven for 5 minutes, after which the rack and skein were removed and allowed to cool for 5 minutes, after which the 1.5 mg/denier weight was left on the skein for the remainder of the testing and conditioned for a minimum of 2 hours at 70°F +/- 1°F (21 +/- 1°C) and 65% +/- 2% relative humidity. The length of the skein was measured to the nearest mm and recorded as "Ca." A 1000 g weight was then hung from the bottom of the skein, allowed to equilibrate, and the length of the skein was measured to the nearest mm and recorded as "La." The crimp shrinkage "CCa" value (%) after heating was calculated using the following formula:
%CCa=100x(La-Ca)/La

Intrinsic viscosity (IV) was determined using a Viscoteck Y 501C Forced Flow Viscometer (Malvern Corporation, Houston, Texas, USA). 0.15 grams of sample was weighed into a 40 mL glass vial containing 30 mL of solvent (phenol/1,1,2,2-tetrachloroethane (60/40 wt%)) and a stir bar. The sample was then placed in a preheated heat block at 100°C, heated and stirred for 30 minutes, removed from the block, and allowed to cool for 30-45 minutes before being placed in the viscometer's autosampler rack. The sample was then analyzed according to ASTM method D5225-92 (Standard Test Method for Measuring Solution Viscosity of Polymers Using 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, and the 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 were obtained from NanYa Plastics Corporation, Livingston, New Jersey, USA.

The polymer blend composition was made from a physical blend of 0.96 IV PTT pellets and 0.82 IV PET copolymer pellets (a "salt-and-pepper" (S&P) blend) prior to extrusion. These pellet blends were intimately mixed during the extrusion process during spinning. Alternatively, in some examples, the PTT pellets and PET copolymer pellets were compounded in a twin-screw extruder and pelletized for direct use during spinning without the need to create a salt-and-pepper blend.

In preparation for melt spinning, the pellets were dried under nitrogen in a vacuum oven at 120°C and 25 inches of mercury vacuum for 15 hours. The dried pellets were transferred directly to the nitrogen-purged feed hopper of the spinning machine.

Fiber Preparation The two components of the bicomponent fibers were melt spun using processes and equipment generally applicable to spinning side-by-side and eccentric sheath/core bicomponent fibers, such as those disclosed in U.S. Pat. Nos. 6,641,916 B1, 6,803,102, and 7,615,173 B2, which are incorporated herein by reference.

For spinning the bicomponent fibers of the examples, polymers were melted in a pair of Werner & Pfleiderer 28-mm co-rotating twin-screw extruders with capacities ranging from 0.5 to 40 lbs/hr (0.23 to 18.1 kg/hr). One extruder, referred to herein as the East extruder, was used to melt PET homopolymer (IV 0.50 and 0.64) pellets, and the second extruder, referred to herein as the West extruder, was used to melt 1) PTT pellets alone, 2) a salt-and-pepper ("S&P") blend of PTT pellets and co-PET copolymer pellets, or 3) compounded PTT/co-PET pellets. The temperatures of the West extruder, spin block, and East extruder are listed in the examples. Each extruder fed a spin block containing a concave spinneret. The spinneret used was a post-coalescence, side-by-side, bicomponent spinneret with 34 pairs of capillaries arranged in a circle, with an internal angle of 30 degrees between each pair of capillaries, a capillary diameter of 0.64 mm, and a capillary length of 4.24 mm.

The bicomponent filaments exiting the spinneret were cooled by cross-flow quench air at a nominal temperature of 20°C and a face speed of 0.5 mm/s. The filaments then advanced to a dual feed roll operating at approximately 800-1200 meters/min, depending on the draw ratio. A finish applicator was used to apply lubricant to the filament bundle between the spinneret and the feed roll. To affect the draw, the feed roll was typically heated to 70°C. The filament bundle was then accelerated to an anneal roll operating at a speed of approximately 3000-3600 m/min, depending on the desired draw ratio; the anneal roll temperature was typically 170°C. The annealed bicomponent fibers then advanced to two sets of dual let-down rolls operating at room temperature before being wound on a Barmag SW6 600 winder. The fibers had a snowman-shaped (rectangular) cross-sectional shape.

Example 1
Variation of PTT Intrinsic Viscosity (IV) Example 1 illustrates the use of PTT pellets with different IVs to produce bicomponent fibers with desired values of crimp shrinkage after heating (CCa). The IV of the PTT pellets used to make the fibers was either 1.25 dl/g (1a) or 1.02 dl/g (1b). The IV of the PET pellets was 0.64 dl/g in both cases. In each example, the weight ratio of PTT to PET was 50/50. Example 1-a was a 115 denier, 34-filament fiber. Example 1-b was a 75 denier, 34-filament fiber.

Example 2
Variation of PTT/PET Weight Ratio Example 2 illustrates how varying the weight ratio of the PTT component to the PET component in the bicomponent fiber affects the crimp shrinkage (CCa) after heating. The bicomponent fiber was 75 denier with 34 filaments. In Table 2, Comparative Examples A, B, and C exhibit high levels of CCa, i.e., greater than 30%, making them more suitable for apparel applications requiring stretch and recovery. Examples 2a, 2b, and 2c illustrate process conditions that result in high-bulk bicomponent fibers with a crimp shrinkage of 30% or less after heating, suitable for carpet manufacturing. The 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.

Example 3
Variation in the weight ratio between the two components when a constant PTT/co-PET blend is used as the first component. Table 3 shows examples where the first component was made from 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 PTT pellets with an IV of 0.96 dl/g and co-PET pellets with an IV of 0.82 dl/g were mixed together until the pellets were randomly dispersed. After drying, the pellet mixture was fed into the West extruder. Dried PET homopolymer pellets with an IV of 0.50 were fed into the East extruder. Bicomponent fibers were then made where the first component comprised the 50/50 weight ratio PTT/co-PET blend described above and the second component was PET, varying the weight ratio between the two components. For example, Example 3a was made with a weight ratio between the first component (i.e., a 50/50 PTT/co-PET blend) and the second component (i.e., PET) of 70/30. For the remaining examples in Table 3, the polymers remained the same, but the weight ratio between the two components was varied. The winder speed was 3500 m/min for all of these examples.

Example 4
Varying the PTT/co-PET Blend Ratio in the First Component While Fixing the Weight Ratio Between the Two Components. Table 4 shows an example where the first component was made from a blend of PTT and co-PET, and the second component was made from PET. In contrast to Table 3, the examples in Table 4 demonstrate the effect of varying the blend ratio of PTT to co-PET in the first component while maintaining a constant 50/50 weight ratio between the two components. In Table 4, Examples 4a-4d and 4f-4g, as well as Comparative Example D, were made by varying the pellet ratio in a "salt-and-pepper blend"("S&P") of PTT with an IV of 0.96 dl/g and co-PET with an IV of 0.82 dl/g. The pellets were mixed together until randomly dispersed. After drying, the pellet mixture was fed into the West extruder. Dried PET homopolymer pellets with an IV of 0.50 were fed into the East extruder. Next, bicomponent fibers were prepared, with the first component comprising the aforementioned PTT/co-PET blend and the second component consisting of PET, with the weight ratio between the two components fixed at 50/50. For example, in Example 4a, the first component was prepared from a 10/90 blend of PTT/co-PET, and the second component was prepared from PET. The weight ratio between the two components was 50/50. In Example 4e, PTT and co-PET pellets were precompounded in a twin-screw extruder, quenched, pelletized, and re-dried before use. This contrasts with Example 4d, in which the components were prepared from a salt-and-pepper blend. It should also be noted that Comparative Example D had a higher crimp shrinkage value after heating, %CCa = 43.1, making it more suitable for apparel fabrics with high levels of stretch.

For Example 4-a, the winder speed was 3,475 m/min, and for Examples 4-b, 4-c, 4-d, 4-e, 4-f, 4-g, and Comparative Example D, the winder speed was 3,500 m/min.

Example 5
Carpet Production Using Self-bulking Bicomponent Fibers as in Example 2a: Carpets containing self-bulking bicomponent fibers can be spun at 1200 denier - 120 filaments (10 dpf) using the polymers, polymer IVs, and fiber weight ratios described in Example 2a above. These bicomponent fibers will have a higher denier and filament count than the fibers in Example 2a. The spinning speed (i.e., draw ratio) will be adjusted so that the resulting fibers have a post-heat crimp shrinkage of 30% or less. The bicomponent fibers thus produced can then be twisted with a second bicomponent fiber of the same type using standard twisting equipment. After twisting, the fibers can be treated with a Superba® heat setting device, which fully develops the crimp of the bicomponent fiber and sets the twist of the twisted yarn. The heat-set bicomponent yarns are then tufted into a polypropylene nonwoven backing along with other heat-set yarns of the same composition in a standard carpet tufting machine to produce a tufted fabric consisting entirely of heat-set bicomponent plied yarns. The tufted fabric can then be processed in standard carpet industry processing equipment to apply a latex formulation to the carpet backing and bond the tufted face fibers to the backside of the carpet fabric. A secondary backing can then be applied to protect the underside of the carpet. The greige (undried) carpet can then be processed in standard continuous dyeing equipment and then dried in a continuous oven to remove moisture. The finished carpet is then wound onto a large tube for on-site installation.

Example 6
Carpet Products Using Self-bulking Bicomponent Fibers as in Example 2a but with a Trilobal Cross-Section: Carpets containing self-bulking bicomponent fibers can be spun at 1200 denier - 120 filaments (10 dpf) using the polymer, polymer IV, and fiber weight ratio described in Example 2a above. While any other cross-section useful in carpet manufacturing can be selected, the spinneret orifices are chosen to produce a side-by-side trilobal cross-section. These bicomponent fibers will have a higher denier and filament count than those in Example 2a and the trilobal cross-section. The spinning speed (i.e., draw ratio) will be adjusted so that the resulting fibers have a crimp shrinkage after cooking of 30% or less. The bicomponent fibers thus produced can then be twisted with a second bicomponent fiber of the same type using standard twisting equipment. After twisting, the fibers can be processed using a Superba® heat-setting device, which fully develops the crimp of the bicomponent fibers and sets the twist of the twisted yarn. The heat-set bicomponent yarn can then be tufted into a polypropylene nonwoven backing in a standard carpet tufting machine along with other heat-set yarns of the same composition to produce a tufted fabric consisting entirely of heat-set bicomponent plied yarns. The tufted fabric can then be processed using standard processing equipment used in the carpet industry to apply a latex formulation to the carpet backing and bond the tufted face fibers to the backside of the carpet fabric. A secondary backing can then be applied to protect the underside of the carpet. The greige (undried) carpet can then be processed using standard continuous dyeing equipment and then dried in a continuous oven to remove moisture. The finished carpet is then wound onto a large tube for on-site installation.

Claims (12)

A carpet, the face fibers of which comprise bicomponent fibers comprising a first 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) and poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer, wherein the bicomponent fibers are self-bulking by differential shrinkage, in contrast to carpets made from mechanically bulked bulk continuous homofilaments;
The bicomponent fiber has a crimp shrinkage rate after heating of 30% or less when measured according to a crimp shrinkage method.
The carpet. The carpet of claim 1, wherein the bicomponent fibers may be in a side-by-side arrangement or an eccentric sheath/core arrangement. The carpet according to claim 1 or 2, wherein the first and second components of the bicomponent fibers are present in a weight ratio ranging from 80:20 to 20:80. 4. The carpet according to claim 3, wherein the bicomponent fiber has a crimp shrinkage of 30% or less after heating, as determined according to a crimp shrinkage method. The carpet of claim 1, wherein the surface fibers further comprise at least one additional fiber selected from bulked continuous filaments, synthetic staple fibers, and natural fibers. 6. The carpet of claim 5 , wherein the at least one additional fiber is a bulked continuous filament, the bulked continuous filament comprising nylon, polypropylene, or polyester. 6. The carpet of claim 5 , wherein said at least one additional fiber is a synthetic staple fiber, said synthetic staple fiber comprising nylon or polyester. 6. The carpet of claim 5 , wherein the at least one additional fiber is a natural fiber, the natural fiber comprising wool, silk, or cotton. 1. An improved method for making yarn for manufacturing carpet, wherein the face fibers of said carpet comprise self-bulking bicomponent fibers comprising a first 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) and poly(ethylene terephthalate) homopolymer or poly(ethylene terephthalate) copolymer;
The method comprises:
a) extruding the two components in a spinner capable of producing two or more independent melt streams;
b) combining the melt streams in a spinneret suitable for producing bicomponent fibers;
c) quenching the self-bulking bicomponent fibers produced in step (b) in air;
d) drawing and heat setting the self-bulking bicomponent fibers; and e) winding the self-bulking bicomponent fibers by means suitable for subsequent processing into a carpet,
The self-bulking bicomponent fiber does not require a mechanical bulking process ,
The bicomponent fiber has a crimp shrinkage rate after heating of 30% or less when measured according to a crimp shrinkage method.
The method . The method of claim 9 , wherein the bicomponent fibers may be in a side-by-side configuration or an eccentric sheath/core configuration. 11. The method of claim 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 method of claim 11 , wherein the bicomponent fiber has a crimp shrinkage of 30% or less after heating as determined according to the crimp shrinkage method.