Stain resistant multicolor textured cut pile carpet

Stain-resistant, multicolored cationic dyeable carpet fibers are space dyed with an acid dye or premetalized acid dye, heatset, then tufted together with undyed cationic dyeable nylon fibers into a carpet. The carpet is then overdyed with an acid dye or premetalized acid dye to selectively dye only the previously undyed cationic dyeable nylon fibers, without staining or discoloring the adjacent previously dyed fibers, resulting in a multicolored stain resistant carpet.

BACKGROUND OF THE INVENTION 
Stain resistant nylon carpets enjoy significant market acceptance. Stain 
resistance is typically imparted to nylon by treating the fiber as a solid 
filament or in a carpet form by the topical application of a chemical 
finish as described in the following U.S. Pat. Nos. to Monsanto: U.S. Pat. 
Nos. 4,501,591; 4,592,940; and 4,839,212. The low acid pH necessary to fix 
this stain resistant finish has the adverse property of greatly altering 
the shade of the cationic dye which is normally used on this cationic 
dyeable fiber, precluding its use as a styling factor to obtain multicolor 
effects in subsequent carpet. However, by using cationic dyeable nylon, 
which has been previously dyed with acid dyes, in either a solid shade or, 
preferably, space printed to give multiple short spacings of color, this 
complication is overcome. 
Nylon carpet fiber is generally classified as to type depending upon its 
receptivity to acid dyes and basic or cationic dyes. Cationic dyeable 
nylons contain sufficient SO.sub.3 H groups or COOH groups within the 
polymer structure, which groups are receptive to cationic or basic dyes, 
to render the fiber dyeable by a cationic dye. Acid dyeable nylons are 
essentially conventional nylons, such as polyhexamethylene adipamide and 
polycaprolactam. Acid dyeable nylons vary as to receptivity type and are 
characterized as being weakly dyed with acid dyes, average dyed with acid 
dyes, or deeply dyed with acid dyes. 
Cationic dyeable nylons generally exhibit inherent stain resistant 
properties, especially to acid-type stains, as compared to other nylon 
types used for carpet. Cationic dyeable nylons are dyeable with selected 
cationic dyes, but suffer from poorer lightfastness, especially in light 
shades, than do comparable shades dyed on acid dyeable nylon using 
monosulfonated or premetalized acid dyes. This has resulted in the 
under-utilization of cationic dyeable nylon as a carpet fiber. The fiber's 
inherently useful properties which otherwise make it attractive as a 
carpet fiber previously have not been fully realized. 
Initial dyeing is accomplished using the space dyeing or intermittent 
dyeing technique in which the yarn within a given area or space is dyed a 
particular color, the color and spaces varying throughout the length of 
the yarn according to random or predetermined orders. 
Dyeing carpet yarn is described in U.S. Pat. No. 4,206,735 which relates to 
a carpet prepared by space dyeing a polyester or polypropylene yarn then 
tufting the space dyed yarn with another yarn, undyed and having a 
susceptibility to a dye to which the polyester or polypropylene space 
dyeing yarn is not susceptible, followed by dyeing the undyed yarn taking 
care that the selective dyeability of the undyed yarn does not interfere 
with the previously space dyed yarn. Tak dyeing is used to provide 
coloration for nylon tufts and Tak dyeing is explained in U.S. Pat. No. 
4,146,362. 
Another type of space dyeing is described in U.S. Pat. No. 4,033,717 to 
Whitaker in which a continuous filament yarn is knit into a prefabric such 
as a tube or a sock, selectively dyed in a predetermined pattern using 
various colors, then deknitted, wound onto cones and heated to develop the 
color. This is also known as a knit/deknit process. When tufted into a 
carpet, the tufts of the space dyed yarn are arranged randomly or 
preferably in predetermined blocks or areas. 
Research Disclosure 17913 (March 1979) uses the space dyed yarns of the 
Whitaker patent, combines them with undyed yarns, then overdyes to a 
different color to provide a carpet having different color combinations. 
Space dyed yarns may also be prepared using "resist" techniques to treat 
the fabric to "resist" the type of dye employed, as described in Jilla, 
U.S. Pat. No. 3,989,453. 
Piece dyeing carpets using carpet pile made from two or more different 
classes of yarns, one yarn being susceptible to one type of dyeing and the 
other class of yarns susceptible to a different type of dye, is described 
in U.S. Pat. No. 3,439,999. 
My earlier U.S. Pat. No. 5,085,667, the disclosure of which is hereby 
incorporated by reference, describes carpets made entirely of cationic 
dyeable nylon dyed an overall level shade with an acid or premetalized 
acid dye. These carpets enjoy the inherent stain resistance of cationic 
dyeable nylon and also exhibit high resistance to ozone and lightfastness. 
My earlier application Ser. No. 07/732,201, the disclosure of which is 
hereby incorporated by reference, describes a stain-resistant multicolored 
carpet composed of cationic dyeable nylon yarn dyed with an acid dye or a 
premetalized acid dye and an acid dyeable nylon (undyed) tufted with the 
previously dyed cationic dyeable nylon into a carpet then overdyed with an 
acid dye to selectively dye the acid dyeable nylon yet neither dye nor 
stain the previously dyed cationic nylon fibers. This technique results in 
an attractive multicolor carpet although the acid dyeable nylon lacks the 
important, desirable stain resistant characteristic of cationic dyeable 
nylon.

DESCRIPTION OF THE INVENTION 
The present invention provides an attractive multicolored carpet 
constructed entirely of cationic-dyeable nylon having the desired visual 
impact, amenable to a wide variety of styling and pattern changes, 
combined with the inherent stain resistance of cationic dyeable nylon. 
The multicolor cationic dyeable nylon carpet yarn of the present invention, 
and tufted carpets made from it, are achieved utilizing solid or space 
dyed yarn prepared according to the techniques described in my U.S. Pat. 
No. 5,085,667, the disclosure of which is hereby incorporated by 
reference, which optionally is twisted or air entangled with another dyed 
cationic dyeable nylon, then heat set with dry heat at temperatures in the 
range of 160.degree. C. to 220.degree. C. A detailed discussion of 
heatsetting conditions and operational parameters is given below. 
The resulting dyed yarn is pleated in carpet with an undyed cationic 
dyeable nylon and remains unstained in its original shade when carpet 
containing both dyed and undyed yarns is overdyed with acid or 
premetalized acid dyes to color the undyed yarn. The resulting carpet 
contains a multitude of colors resulting from the mixing of fibers of 
diverse shades, the physical arrangement and tufting of inherently stain 
resistant undyed fibers with other previously dyed fibers followed by 
overdyeing to selectively dye the undyed fibers only, without staining or 
discoloring the adjacent previously dyed fibers. The carpet is composed 
entirely of cationic dyeable nylon and takes full advantage of this 
fiber's inherent resistance to stains, particularly acid-type food stains. 
This invention provides a procedure for preparing stain resistant carpet 
having an attractive multicolored appearance composed of cationic dyeable 
nylon. 
A multicolored carpet is created according to this invention using cationic 
dyeable nylon yarn, which has been space dyed or printed to multiple 
colors with premetalized acid or acid dyes according to techniques 
outlined in my earlier U.S. Pat. No. 5,085,667. This multicolored yarn is 
combined, if desired, with other similarly dyed cationic dyeable nylon 
yarn, heatset in dry circulating air, tufted into a carpet, planted with a 
previously undyed cationic nylon yarn then overdyed with an acid or 
premetalized acid dye. Heatsetting closes the crystalline fiber structure 
of the thus treated cationic dyeable nylon rendering it resistant to 
dyeing or staining during the subsequent overdyeing process. During the 
overdyeing process the acid dye fixes to the undyed cationic dyeable nylon 
but not the previously dyed and heatset cationic dyeable nylon yarns 
leaving the multicolored spaced dyed yarn clear without staining or 
discoloring and distinct against a contrasting field of solid color yarns. 
Variations in the colors of the multicolored cationic dyeable nylon yarn, 
the shade of the background cationic dyeable nylon yarn, the relative 
amounts and positioning of the two shades of yarn, their construction into 
a carpet and other factors all provide attractive variations. 
Heatsetting closes the crystalline structure of the nylon fibers imparting 
further stain resistance. Heatsetting is accomplished using times and 
temperatures consistent with the physical properties and characteristics 
of the nylon fibers employed. It is important that the heating temperature 
stay below the softening/melting point of the nylon as established by the 
fiber producer's data specific to fiber type. As an illustration, for type 
66 nylon the softening/melting temperature is in the 240.degree. C. to 
255.degree. C. range and a range of 208.degree. C. to 212.degree. C. for 
type 6 nylon. Preferably a maximum heating temperature is chosen to be 
about 20.degree. C. below the softening/melting point of the fiber used. 
Heating times are selected to avoid fiber yellowing leading to change of 
shade, fastness to light and reduced performance while the time the fibers 
are exposed to heat must be sufficient to close the fiber's crystalline 
structure. Heating times are related to heating temperatures and these two 
variables are selected such that during heatsetting operations the fiber 
reaches a temperature not exceeding its melting/softening point. 
Preferably heating times of about one minute, plus or minus 20 seconds at 
the temperature ranges noted above is sufficient to achieve bleach 
resistance while maintaining the other desired properties of fastness to 
light, resistance to acid-type stains, shade consistency and the like. 
Shorter times and lower temperatures reduce the effectiveness of the 
heatsetting treatment in closing the crystalline structure of the nylon 
fibers. 
The nylon yarns are heat set under dry or very low moisture conditions in 
contrast to wet heatsetting procedures such as an autoclave or a Superba 
unit which use pressurized steam atmospheres. Dry air assures closing the 
fiber's crystalline structure while heatsetting in a moist environment 
opens the fiber's crystalline structure. Dry circulating air is preferred. 
Heated drums or rolls may be used but they tend to polish or partially 
remove crimp from the fibers. 
Heatsetting is accomplished at temperatures in the range of 160.degree. C. 
to 220.degree. C. and preferably in a temperature range of about 
195.degree. to about 220.degree. C. for a period of time of from about 40 
seconds to about 80 seconds, generally about 1 minute. Type 66 cationic 
dyeable nylon is preferably heatset at temperatures in the range of about 
195.degree. C. to about 220.degree. C. and for type 6 cationic dyeable 
nylon temperatures in the range of about 160.degree. C. to about 
180.degree. C. Preferably the heatsetting is conducted in dry circulating 
air. 
The preferred techniques for overdyeing the cationic dyeable nylon carpet 
include exhaust dyeing, pad/steam continuous carpet dyeing and the like. 
Illustrative examples for dyeing procedures thought to be suited to the 
process of this invention are: 
Continuous Dye Method 
A dye bath is prepared as follows: 
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Continuous Dye Method - A dye bath is prepared as follows: 
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Dye Solubilizer -Thiodiglycol (Kromfax) - 
1.5 g/l 
Dye Leveling Agent - Sedgelev ACB - 
0.5 g/l 
Defoamer- Sedgekill AO - 0.33 g/l 
Premetalized acid dyestuff- 
X g/l 
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(pH of bath adjusted to 6.0 with monosodium phosphate) 
and applied to the cationic dyeable nylon carpet at a wet pickup of 400% 
based upon the weight of the carpet. For proper fixation, the carpet is 
steamed for 6-12 minutes then washed, extracted, treated with a 
fluorochemical soil repellant and dried. 
Exhaust Dyeing 
an aqueous dyebath is prepared containing the required amount of 
premetalized acid dyestuff, the pH adjusted to 6.0 with monosodium 
phosphate and, optionally, up to 0.5% Irgasol SW, a weakly cationic 
complexing agent which retards the strike of the acid dye by complexing 
with the dye and then slowly releasing the dye to the fiber as the 
temperature rises, is added. The dyebath temperature, initially at 
80.degree. F., is increased at a rate of 2.degree. F. per minute to 
140.degree. F. and held there for 15 minutes, then raised again at 
2.degree. F. per minute to 208.degree.-212.degree. F. Cationic dye able 
nylon is then exhaust dyed for 30 to 60 minutes or longer as needed to 
achieve the desired depth of shade.