Knit structure dyeing before tufting carpets

Description

Technical Field

[0001] This invention relates to a process for making carpets of greater color and shade uniformity by dyeing a knit structure under low tension, passing the knit structure through at least two squeeze rollers, unravelling the knit structure and making a carpet from the unravelled dyed yarns.

Background

[0002] Wool carpet yarns have traditionally been dyed in hanks then spooled for weaving or tufting into carpets. Synthetic yarns such as nylon followed the same techniques as wool at first, and some yarns are still yarn dyed for use in pattern weaving. However, the great majority of synthetic carpet yarns, particularly bulked continuous filament, are now undyed when made into carpet form, and the entire carpet is dyed to a solid shade or is printed when color patterning is desired.

[0003] The advantages of dyeing in carpet form are lower processing cost per pound of yarn and better shade uniformity of solid colors than yarn dyed. Disadvantages are the high investment and floor space cost of the dyeing equipment and difficulty in attaining precise shade uniformity across the entire width of a carpet as much as 15 feet (4.6 meters) wide. Tufting is now the major means of making carpet, wherein a plurality of yarns is fed to an array of sewing-machine-type needles closely spaced across the entire width of a carpet backing fabric, and the up and down motion of the needles inserts the yarns into the backing to form loops on the opposite side. The creel required to hold up to about 1800 yarn packages from which the yarns are delivered to the tufting needles also requires a large amount of floor space.

[0004] If one or a number of the yarns have a different degree of dyeability from the others, they will form visible light or dark streaks through the entire length of carpet after dyeing making it unacceptable. However, such a defect cannot be detected until after the carpet has been dyed.

[0005] Previous patents have disclosed methods of assembling multiple yarns into a temporary woven or knitted structure for ease of handling then later removing a temporary weft thread or deknitting a knitted structure to separate the yarns for feeding subsequent operations. Honda et al U.S. Patent No. 3,536,019 discloses inserting and removing a temporary weft thread, Whitaker U.S. 4,045,848 shows destroying such a temporary weft, and Hutcheson U.S. 4,327,464 discloses knitting and deknitting. In addition, Whitaker and Hutcheson disclose dyeing and printing such temporary structures with multi-colored patterns to obtain "space dyed" or Berber effect yarns. There was no realization that such temporary structures could be used in conjunction with specific dye application methods to achieve superior uniformity of solid-shade colors.

SUMMARY OF THE INVENTION

[0006] A process for making a carpet of good color and shade uniformity from dyed yarn has now been discovered comprising the steps of:

a. assembling crimped yarns into a multi-end ribbon-like structure;

b. dyeing the ribbon-like structure by first feeding said ribbon-like structure into a dye bath at low tension and then forcing the dye through each yarn in the ribbon-like structure at least twice preferably by feeding the ribbon-like structure through at least two squeeze rollers, wherein the squeeze rollers force the dye through each yarn in the ribbon-like structure and remove excess dye;

c. fixing the dye by heating the ribbon-like structure, preferably heating by steam at approximately 100°C.

d. rinsing and squeezing the ribbon-like structure;

e. drying the ribbon-like structure;

f. unravelling the ribbon-like structure to separate the yarns; and

g. feeding the unravelled yarns into a carpet tufting machine, wherein a carpet of good color and shade uniformity is made.

[0007] The crimped yarns are preferably assembled into the ribbon-like structure by warp knitting or loose weaving characterized by insertion of weft thread, wherein the weft thread is removed when the ribbon-like structure is unravelled.

[0008] Fresh dye is preferably added continuously to the dye applicator so that all yarn is treated with dye of a uniform concentration. The dye may be forced repeatedly through the yarns by two or more sets of squeeze rollers or by other means such as two or more sets of jets or sprays from one or both sides or by pulling the yarn under low tension in wrapping contact with one or more stationary wiper bars to redistribute dye on and within the yarns.

[0009] The yarns may be assembled into multi-end ribbon-like structure by temporary loose weaving, employing a weft yarn which is later removed, or by warp knitting, preferably using a low stitch density construction to minimize the bulk of the assembly and to reduce permanent distortion of the yarns into a knit-de-knit crimp form. The use of previously twist-set yarns is preferred for avoiding such distortion. The ribbon-like structure is later unravelled to separate the yarns.

[0010] Loose weaving or knitting is characterized by along-end weft insertions of about 1 cm or greater or by warp knitting forming continuous stitches of about 2 cm or greater. Such loose construction is necessary for complete and uniform penetration of dye throughout all yarns as well as for thorough steaming, rinsing and drying. Such penetration is also aided by minimum tension on the assembly during the operations, which also is beneficial in preserving optimum crimp and bulk in the yarns.

[0011] A yarn as referred to herein may either be a single yarn or may be two or more single yarns which have been plied and heat set, or may be differentially-dyeable yarns which have been air entangled.

[0012] In dyeing multiple yarns in the present manner, yarn-to-yarn dye uniformity is excellent, and along-end uniformity can be controlled better than in current continuous yarn dyeing practice.

[0013] If any yarns have noticeably different dyeability from the majority, they may be detected visually as the yarns enter the tufting machine and may be removed to waste.

[0014] Dyeing equipment which is suitable with minor modifications for use in the present process is used for dyeing automobile seat belt webbing, for which product the along-end dye uniformity requirements are particularly stringent.

[0015] If desired, other treatments may be given the yarns before, during or after dyeing. Such treatments may impart anti-microbial activity or may repel soil and stains.

[0016] Yarns from ribbon-like arrays of different color may be fed to particular needles of a tufting machine so as to form stripes or other graphic designs.

[0017] The process of the invention may be used with both staple and continuous filament yarns and is advantageous for wool as well as for synthetic fibers. The process may either be continuous from assembling the yarns into a ribbon-like structure to carpet making, or it may be interrupted, as by storing the dyed and dried structure in a can or box and later feeding the structure to carpet making.

[0018] The superior dye uniformity, reduction of investment and floor space savings of the present process can benefit carpet mills of any size. In addition, small carpet mills are particularly aided by the increase in productivity and the reduction in yarn inventory which the present method makes possible. Mills which are distant from a source of yarn, such as in foreign countries, can appreciably reduce their lead time for ordering supplies.

EXAMPLE

[0019] Two hundred yarns each consisting of two 1700 denier trilobal filament nylon 66 bulked continuous filament yarns of 22 denier per filament which have been ply twisted and hea t set together are led from individual packages on a creel to a needle loom and woven on an eight shaft four by four construction inserting one weft thread pick approximately every 1 cm of yarn travel. The multi-end ribbon-like structure is approximately 8 cm wide. The speed of yarn advance is about 10 meters per minute. The ribbon is then fed to a webtex pad steam dyer and is dyed with Ciba Geigy "Tectalon" dyes comprising acid red 361, 3 g/liter, 200% and yellow, 2 g/liter and acid blue 277, 0.5 g/liter, in a bath where two sets of squeeze rollers force the dye through each yarn. Both squeeze rollers removes excess dye to waste, after which the yarns enter a steamer which raises the yarn temperature to about 100°C for an exposure time of 4-1/2 minutes with live steam to set the dye. The yarns are then rinsed and squeezed in six tanks on line and are then dryed at 120°C for 2-1/2 minutes in a convection dryer. The dye uniformity is excellent edge to edge and meets commercial standards end to end. The weft is then withdrawn and the yarns are separated to enter the eyelet board of a carpet tufting machine.

Claims

1. A process for making a carpet of good color and shade uniformity from dyed yarn comprising the steps of:

a. assembling crimped yarns into a multi-end ribbon-like structure;

b. dyeing the ribbon-like structure by first feeding said ribbon-like structure into a dye bath at low tension and then forcing the dye through each yarn in the ribbon-like structure at least twice;

c. fixing the dye by heating the ribbon-like structure;

d. rinsing and squeezing the ribbon-like structure;

e. drying the ribbon-like structure;

f. unravelling the ribbon-like structure to separate the yarns; and

g. feeding the unravelled yarns into a carpet tufting machine, wherein a carpet of good color and shade uniformity is made.

2. The process of Claim 1 wherein the crimped yarns are assembled into the ribbon-like structure by warp knitting.

3. The process of Claim 1 wherein the crimped yarns are assembled into the ribbon-like structure by loose weaving characterized by insertion of weft thread, wherein the weft thread is removed when the ribbon-like structure is unravelled.

4. The process of Claim 1, 2, or 3 wherein the dye is forced through the yarn in the ribbon-like structure by two sets of squeeze rollers.

5. The process of any one of Claims 1 to 4 further comprising the step of removing the excess dye after the dye is forced through the yarn in the ribbon-like structure.

6. The process of any one of Claims 1 to 5 wherein the step of heating to fix the dye is by steaming at approximately 100°C.