DE3853165T2 - METHOD FOR INCREASING THE STAIN RESISTANCE OF CARPET FIBERS. - Google Patents

Abstract

This invention relates to improved methods to enhance stain resistance of dyed nylon carpet fiber by a continuous aftertreatment and to two-step processes, either batch-batch, batch-continuous or continuous-continuous. After preheating with water and extracting to a wet pick-up of between 30 to 190 % by weight, sulfonated aromatic condensates which can be combined with fluorocarbon compounds for soil resistance, thiocyanates, and/or salts having divalent cations, such as magnesium sulfate are applied. Also various dispersing agents, buffering acids and sequestering agents are disclosed.

Description

This invention relates to an improved process for applying a water-soluble thiocyanate on a polyamide fiber.

The following terms are defined for their use in this description:

Sulfonated aromatic condensate (s.a.c.) is understood to mean any condensate of an aromatic compound, whether sulfonated before or after condensation, in particular a sulfonated aromatic formaldehyde condensate (s.a.f.c.) which has the effect of enhancing the stain resistance of a fiber or carpet fabric.

Thiocyanate is any organic or inorganic salt that contains a cation and the thiocyanate anion.

Fluorocarbon refers to those fluorocarbon compounds that have the effect of improving the dirt-repellent properties of a fiber or carpet material.

ICP is the index of crystalline formation as a measured indication of the internal crystal structure of the polymer in an aligned fiber. A high ICP indicates an easily dyeable polymer fiber with an open crystalline internal structure.

Nylon refers to the polyamide family of polymers nylon 6, nylon 6,6, nylon 4, nylon 12 and the other polymers containing the structure &lsqbstr; - &rsqbstr; together with the chain &lsqbstr;CH₂&rsqbstr;x.

Carpet fabric is understood to mean a carpet fiber or carpet yarn that has typically been tufted, woven or otherwise processed into a fabric suitable for end use in home furnishings, in particular as a floor covering.

Fiber is defined as a continuous filament of a continuous or extremely long fiber or a cut or otherwise short fiber known as staple fiber. Carpet yarn may consist of multiple continuous filaments or be made from spun staple fibers, both of which have typically been pre-textured for increased bulk.

By salt containing a divalent cation is meant any such salt which has the effect of enhancing the stain resistance of a fibre, in particular a high ICP nylon fibre, in combination with an effective amount of an s.a.c.

A dispersant is any chemical compound or combination of chemical compounds that has the effect of producing stable, relatively non-precipitating, non-coagulating mixtures of other chemical compounds.

By sequestering agent is meant any chelating agent which is effective in sequestering, i.e. suppressing certain properties of a metal, without removing it from the system or from the phase. To be practical, the sequestering agent must not cause any undesirable change which would render the system unsuitable for its intended purpose. Chelation achieves sequestration mainly by reducing the concentration of free metal ions to a very low level by converting most of the metal into a soluble chelate which does not possess the properties to be suppressed.

A chelating agent is a compound containing donor atoms that can combine with a single metal atom through a coordinate bond to form a chelating complex or simply a chelate. Since the donor atoms are linked intramolecularly by chains of other atoms, a chelate ring is formed for each donor atom after the first one coordinating with the metal. The above is taken from Volume 5, beginning on page 339, of the Kirk-Othmer Encyclopedia of Chemical Technology (John Wiley & Sons), 1979, which passage is hereby incorporated by reference to page 367.

It is known that sulfonated aromatic formaldehyde condensates ("safc") in the yarn finish (during or after fiber quenching) to improve the stain resistance of carpet fibers, see US-A-4,680,212, in the dye bath for the same purpose, see US-A-4,501,591, or incorporated into the fiber for the same purpose, see US-A-4,579,762. The use of a fluorochemical to improve both stain and soil resistance in combination with safc is also taught in US-A-4,680,212, column 5. Other useful fluorochemicals for soil repellency are taught in commonly assigned US-A-4,192,754; 4,209,610; 4,414,277; 4,604,316; and 4,605,587.

It is known to use thiocyanates, such as ammonium thiocyanate, at various process conditions during dyeing as "auxiliaries" for various purposes. See US-A-3,652,199; 3,576,588; 3,387,913; 2,899,262 and 2,615,718.

The use of salts containing a divalent cation such as magnesium sulfate with s.a.f.c. to improve moisture fastness is known from US-A-3,790,344, which is hereby incorporated by reference in its entirety. See also page 48 of a textbook by Rosen, M.J., Surfactants & Interficial Phenomena (Wiley, 1978).

It is also well known to buffer acids, including citric acid, and to use dispersants and/or sequestering agents to use a dye bath to stabilize aqueous chemical formulations.

Nylon carpets can be permanently discolored or stained by certain artificial colorants such as food coloring or oxidizing agents such as acne preparations containing benzoyl peroxide. Sacs applied to the fiber to create an ionic barrier to food coloring make the fiber more stain resistant but are not effective against oxidizing agents. Furthermore, many of the sacs used commercially to make "stain resistant" carpets are themselves susceptible to oxidation when exposed to light and ozone. This causes the sac to yellow and subsequently deteriorate. This is a major influence on the carpet properties. The yellow color of the sac results in a noticeable change in the color of the carpet. The destruction of the sac results in a loss of the stain resistance properties of the carpet.

The use of a nylon fiber treated with a fluorocarbon compound in carpet fabric inhibits the wetting of the fiber surfaces, which in turn prevents any stain remover from being absorbed onto or into the fiber. This prevention of surface wetting may be insufficient if the stain remover is dropped onto the carpet with sufficient force to break the surface energy of the fluorocarbon edge layer, or if it is not washed off the carpet and is left in contact with the fibers for an extended period of time. Carpet treated with compositions containing s.a.c.'s must not impair the soil-inhibiting properties of the fluorocarbon.

The application of s.a.c. to the carpet fabric must be effective and economical and compatible with both untreated and fluorocarbon treated fibers and with both continuous dyeing and Beck or batch dyeing. The same applies to any formulation for s.a.c. application. The formulation for s.a.c. application must result in effective penetration into the carpet fabric. The depletion of the individual active chemical components of any formulation for s.a.c. application must also be effective, if not complete.

Certain nylon polymer fibers have a very open internal crystal structure, namely high ICP polymer fibers, which require large amounts of s.a.c. to impart an effective level of stain resistance. High ICP polymers are usually the result of heat setting processes by heating with high temperature saturated steam.

Some prior compositions and processes are only marginally acceptable in terms of durability of stain resistance when the carpet is steam cleaned with a high pH detergent.

The above-mentioned US-A-3387913, US-A-3576588 and US-A-3652199 relate to the use of thiocyanates at high pH as a dyeing aid.

US-A-3387913 discloses a process for producing dyeings and prints on cellulose, polyester or polyamide fibers by applying water, a thiosulfuric acid derivative of a sulfur dye and a fixing agent. Ammonium thiocyanate is one of a number of fixing agents disclosed in this document for reducing the fading of the dye.

US-A-3576588 discloses the use of a combination of ammonium thiocyanate and ammonium citrate to improve dye fixation by complex formation with a basic dye in a printing paste.

US-A-3652199 discloses a process for improving dye penetration when dyeing polyamide fibers with a cationic dye. The fibers are treated at elevated temperatures with an aqueous bath containing a cationic dye and zinc thiocyanate.

The present invention provides a method for depositing a water-soluble thiocyanate on a polyamide fiber when the fiber is contacted with the thiocyanate, wherein the contacting is carried out at a pH between 1 and 5, preferably between 1 and 4. Preferably between 0.1 and 12% thiocyanate, based on the weight of the fiber, e.g. ammonium, sodium, potassium or zinc thiocyanate, is present during the contacting.

The thiocyanate can be brought into contact with the fibre in a dye bath or after the fibre has been dyed.

If desired, the fiber may contain a fluorocarbon to improve the soil repellency of the fiber, and a sulfonated aromatic condensate may either be present on the fiber or co-applied with the thiocyanate.

The amount of sulfonated aromatic condensate used may preferably comprise between 0.25 and 40 grams of solids of condensate per liter of aqueous solution.

The sulfonated aromatic condensate is preferably formed by condensing formaldehyde with one or more dihydroxy aromatic diphenol sulfones.

The condensate can be formaldehyde-condensed with an alkali metal salt of a paraphenolic acid and with 4,4'-diphenolsulfone.

Thiocyanates can be used in a number of techniques to improve fiber properties. For example, the thiocyanates can be used with s.a.c. and with various added chemicals to improve the fastness of the dye and s.a.c. on the fiber to oxidation. The stain resistance of the nylon fiber, particularly a high ICP nylon fiber, can be improved using s.a.c., thiocyanate and a salt with a divalent cation and with additional added chemicals.

It is possible to continuously treat a dyed nylon carpet fabric to impart improved stain resistance, which treatment comprises preheating the dyed carpet fabric with water at a temperature between 60 and 100ºC (140 and 212ºF) to a moisture absorption of over 75% by weight, and a carpet temperature between 54.4 and 99ºC (130 and 210ºF), extracting the water from the carpet fabric to a moisture absorption of 30 to 190% by weight, and then adding an aqueous solution of an effective amount of a sulfonated aromatic condensate at a pH of 1.5 to 5.5, at a concentration of between 0.25 to 40 grams of condensate solids per liter of aqueous solution, at a moisture absorption of between 200 and 650% by weight, and an aqueous solution liquid temperature of between 60 and 100ºC (140 and 212ºF) to achieve a carpet temperature between 54.4 and 99ºC (130 and 210ºF), after which the carpet is held in the aqueous solution at a temperature above 54.4ºC (130ºF) for 0.5 to 90 seconds. The carpet can then be washed in water. The preferred sulfonated aromatic condensate was treated with formaldehyde condensed. The extraction method may be one in which a vacuum is applied to the wet carpet fabric or by compressing the wet carpet fabric through a pair of rollers. The preferred concentration of the condensate is between 0.25 and 10 grams per liter of aqueous solution. The preferred moisture uptake of the aqueous solution is between 300 and 600% by weight. If the aqueous solution is applied by pressure contact with the carpet fabric, the preferred maximum moisture uptake is 450%. If the aqueous solution is applied by spraying, the preferred maximum moisture uptake is 400%. It is preferred to hold the carpet fabric in the aqueous solution for between 2 and 30 seconds. The preferred moisture uptake after extraction is between 50 and 150% by weight. The sulfonated aromatic formaldehyde condensate may be formed by condensing formaldehyde with one or more phenols. At least one of the phenols may be phenol sulfonic acid or the alkali metal salt thereof. It is preferred that one of the phenols is a dihydroxyaromatic diphenol sulfone. Most preferably, the condensate is formaldehyde condensed with the alkali metal salt of a phara-phenol sulfonic acid and with 4,4'-diphenol sulfone. The carpet fabric being dyed of this process may also contain an effective amount of a fluorocarbon compound intended to improve the soil resistance of the carpet. The preferred amount of fluorocarbon present is an amount of from 0.05 to 0.4% by weight of the fabric. The fluorocarbon may contain a perfluoroalkyl radical or it may be a mixture of fluorinated pyromellitate oligomers. A more preferred fluorocarbon is a mixture of pyromellitate oligomers formed by two reactions, namely firstly the reaction of pyromellitic dianhydride with a fluorinated alcohol and secondly the reaction product of the first reaction is further reacted with epichlorohydrin. Another preferred fluorocarbon is a reaction product of a perfluoroalkyl alcohol or amide with a suitable anhydride or isocyanate. Another more preferred Fluorocarbon is a reaction product of N-ethyl perfluorooctyl sulfamideoethanol with toluene diisocyanate. The aqueous solution of this process will also contain an effective amount of a thiocyanate. The thiocyanate cation can be an ammonium, sodium, potassium, copper, zinc, ferrous, ferric, methyl or phenyl cation, with ammonium being preferred. The aqueous solution of this process can also contain an effective amount of a dispersant. The dispersant can be a condensed naphthalene salt, alkyl sulfosuccinate or mixtures thereof. The preferred dispersant is a mixture of a sodium salt of a condensed naphthalene sulfonic acid and di-isobutyl sulfosuccinate. The aqueous solution of this process can also contain an effective amount of a salt having a divalent cation. The preferred salt is calcium, magnesium, zinc or ferrous chloride, sulfate or phosphate, the most preferred of which is magnesium sulfate. The preferred aqueous solution would comprise the combination of a sulfonated aromatic condensate, a divalent cation-containing salt, the thiocyanate and a dispersant, the most preferred combination being where the condensate is formaldehyde-condensed with the alkali metal salt of para-phenol sulfonic acid and with 4,4'-diphenol sulfone, the thiocyanate is ammonium thiocyanate, the divalent cationic salt is magnesium sulfate and the preferred dispersants are di-isobutyl sulfosuccinate and the sodium salt of a condensed naphthalene sulfonic acid in a mixture. The preferred carpet fabric would comprise a fiber treated with a fluorocarbon. The fluorocarbon is a mixture of pyromellitate oligomers formed by two reactions, namely, firstly, the reaction of pyromellitic dianhydride with a fluorinated alcohol, and secondly, the reaction product of the first reaction is further reacted with epichlorohydrin. The amounts of fluorocarbon present on the carpet fabric used in this process are an amount between 0.05 and 0.4% by weight of the fabric, with the magnesium sulfate in the aqueous solution of the process being present in an amount between 0.05 and 0.8% by weight of the substance, the ammonium thiocyanate may be present in an amount of between 0.03 and 1% by weight of the substance, the sulfonated aromatic condensate may be present in an amount of between 0.15 and 7.5% by weight of the substance, the dialkyl sulfosuccinate may be present in an amount of between 0 and 2 parts by weight to the parts by weight of the sulfonated aromatic condensate and the sodium of the condensed naphthalene may be present in an amount of between 0 and 3 parts by weight to the parts by weight of the sulfonated aromatic condensate. The preferred amounts of the compounds are from 0.05 to 0.4% by weight of the fabric of fluorocarbon, from 0.08 to 0.4% by weight of the fabric of magnesium sulfate, from 0.15 to 0.7% by weight of the fabric of ammonium thiocyanate, and from 0.15 to 1.5% by weight of the fabric of sulfonated aromatic condensate, with the dialkyl sulfosuccinate being present in an amount of from 0 to 2.5 parts by weight to the parts by weight of the sulfonated aromatic condensate, and the sodium salt of condensed naphthalic acid being present in an amount of from 0 to 2 parts by weight to the parts by weight of the sulfonated aromatic condensate. To improve the yellowing of the carpet fabric, any of the above aqueous solutions can be buffered with an effective amount of citric acid or any other acid with a sequestrant. The preferred aqueous solution is buffered with an amount of citric acid between 0.3 and 5.5 grams per liter of aqueous solution.

A two-step process embodiment of this invention uses the post-treatment process described above, but prior to the initial preheating step of this post-treatment, an effective amount of the sulfonated aromatic condensate is added during the dyeing of the carpet fabric such that the total effective amounts of sulfonated aromatic condensate in both steps are less than the total effective amount useful in either the first dyeing step only or the subsequent application step only, or such that a more effective level of stain resistance of the carpet fabric is achieved with the same total of the effective amounts of sulfonated aromatic condensate in the two steps as compared to the same amount in only a single step. An effective amount of the salt having a divalent cation can be added during dyeing so that the sac on the fiber is depleted at the possibly higher pH and so that the stain resistance of the nylon fiber in the carpet fabric, particularly an easily dyeable nylon fiber having a high crystalline formation index and having a very open internal crystal polymer structure, is enhanced and the durability of the stain resistance when steam cleaned is improved, or the effective amount of sulfonated aromatic condensate is lower to achieve the same level of stain resistance. The divalent salt can again be a calcium, zinc, magnesium or ferrous sulfate, chloride or phosphate. The preferred salt is magnesium sulfate. The preferred amounts of sulfonated aromatic condensate added during dyeing and after dyeing are between 0.05% based on the weight of the fiber to 0.5% based on the weight of the fiber during dyeing and an additional 0.05% based on the weight of the fiber to 7.5% based on the weight of the fiber after dyeing. Also, the preferred amounts of magnesium sulfate are 0.03 to 1% by weight of the fiber when added to the dye bath and 0.05 to 1% by weight of the fiber when added after dyeing. The carpet fabric used in the process may contain a fluorocarbon present before dyeing. The fluorocarbon in turn may contain a perfluoroalkyl radical or a mixture of fluorinated pyromellitic oligomers. The preferred fluorocarbon is a mixture of pyromellitic oligomers formed by two reactions, namely firstly the reaction of pyromellitic dianhydride with a fluorinated alcohol and secondly the reaction product of the first reaction further reacted with epichlorohydrin. The preceding dyeing step can either be a continuous dyeing process or it can be a batch or Beck dyeing. The Beck dyeing can be carried out in the presence of an effective amount of a salt containing a divalent cation so as to enhance the stain resistance of the carpet fabric. The preferred amount of magnesium sulfate in the dye bath is an amount between 0.2%, based on the weight of the fiber, to 5%, based on the weight of the fiber.

Another method for improving the stain resistance of nylon or wool fibers comprises treating the fiber with a combination of an effective amount each of a sulfonated aromatic condensate and a thiocyanate, thereby imparting to the sac and dye on the fiber improved oxidation resistance to ozone or other strong oxidizing agents such as benzoyl peroxide. The preferred fiber is a carpet fiber, the preferred aromatic condensate is a sulfonated aromatic formaldehyde condensate formed by condensing with one or more phenols. At least one of the phenols may be a phenolsulfonic acid or the alkali metal salt thereof. Or at least one of the phenols may be a sulfone. The sulfone may be a dihydroxy aromatic diphenol sulfone. The preferred condensate is that condensate formaldehyde condensed with an alkali metal salt of para-phenolsulfonic acid and with 4,4'-diphenol sulfone. This method of improving the stain resistance of nylon or wool fibers using a thiocyanate with the sulfonated aromatic condensate may use a thiocyanate selected from the group consisting of ammonium, sodium, potassium, copper, zinc, ferrous, ferric, methyl and phenyl thiocyanate. The most preferred of these is ammonium thiocyanate. The dispersant may be added to the mixture which is also applied to the fiber in this method. The dispersant may be selected from the group consisting of condensed naphthalene salt, an alkyl sulfosuccinate or a mixture thereof. The preferred dispersant is a mixture of a sodium salt of a condensed naphthalene sulfonic acid and di-isobutyl sulfosuccinate. The amounts preferably used in this method are between 0.05 and 10% sulfonated aromatic Condensate, based on the weight of the fiber, between 0.1 and 5% thiocyanate, based on the weight of the fiber, and the sodium salt of the condensed naphthalene-containing sulfonic acid is added in an amount between 0 and 3 parts by weight to the parts by weight of the sulfonated aromatic condensate and the di-isobutyl sulfosuccinate is added in an amount between 0 and 6 parts by weight to the parts by weight of the sulfonated aromatic condensate.

Yet another method of improving the stain resistance of a nylon fiber, particularly a high crystalline formation index fiber for carpets, comprises treating the fiber with a combination of an effective amount each of a sulfonated aromatic condensate, a thiocyanate and a salt with a divalent cation. The sulfonated aromatic condensate may be a condensate with formaldehyde, it may be formed by condensing formaldehyde with one or more phenols, and at least one of the phenols may be phenolsulfonic acid and the alkali metal salt thereof or sulfone. The preferred condensate is that condensed with an alkali metal salt of para-phenolsulfonic acid and formaldehyde-condensed with 4,4'-diphenolsulfone. The preferred thiocyanate is ammonium cyanate, but the thiocyanate may be an ammonium, sodium, potassium, copper, zinc, ferrous, ferric, methyl or phenyl thiocyanate. The preferred salt is magnesium sulfate, but the salt may be a calcium, magnesium or ferrous chloride, sulfate or phosphate. The treated fiber may comprise an effective amount of the fluorocarbon compound intended to enhance the soil resistance of the fiber. The preferred fluorocarbon is a mixture of pyromellitate oligomers formed by two reactions, namely, first, the reaction of pyromellitic dianhydride with a fluorinated alcohol, and second, the reaction product of the first reaction is further reacted with epichlorohydrin. A dispersant may be added to the combination used to treat the fiber in this process. Dispersants may be condensed naphthalene salt or an alkyl sulfosuccinate. or a mixture thereof. The preferred amounts are between 0.15 and 7.5% sulfonated aromatic condensate based on the weight of the fiber, between 0.15 and 1% thiocyanate based on the weight of the fiber, between 0.05 and 0.8% of a salt containing a divalent cation based on the weight of the fiber, and between 0.05 and 0.4% of fluorocarbon present on the fiber prior to dyeing based on the weight of the fiber. As above, the condensate and thiocyanate may be buffered with an effective amount of citric acid or any acid with a sequestering agent so as to reduce light-induced yellowing of the stain-resistant fiber.

Another two-step process is a process for dyeing and treating in two steps (either batchwise or Beck) nylon carpet fabric to impart improved stain resistance, which process comprises, in a first step, dyeing dyed carpet fabric in a dye bath liquid in the presence of an effective amount of a sulfonated aromatic condensate in an aqueous solution at elevated temperature, after which the dye bath liquid is removed from the dyed carpet fabric and the dyed carpet fabric is subsequently rinsed, and thereafter, in a second step, applying to the dyed carpet fabric a further effective amount of a sulfonated aromatic condensate in an aqueous solution at a pH of between 1.5 to 5.5 at a liquid temperature of between 60 and 91°C (110 and 195°F) such that the total effective amounts of sulfonated aromatic condensate in both steps is less than the total effective amount used in either the first dyeing steps alone or is only useful in a subsequent application step, or such that the same total amount of effective amounts of sulfonated aromatic condensate in the two steps will provide a more effective level of stain resistance of the carpet fabric compared to the same amount in only one of the two steps. The dyeing conditions in the first step are a liquid to fabric ratio of 10:1 to 100:1 at a Temperature of 70 to 100ºC (158 to 212ºF) for 15 to 90 minutes. Preferred conditions for the second step are a liquid to fabric ratio of 10:1 to 100:1 for a period of 5 to 60 minutes. The carpet fabric may also be rinsed following the second step. The sulfonated aromatic condensate may be condensed with formaldehyde. The sulfonated aromatic formaldehyde condensate may be formed by condensing formaldehyde with one or more phenols. The phenols may be phenolsulfonic acid or the alkali metal salt thereof. Or the phenol may be an aromatic dihydroxy diphenol sulfone. The preferred condensate is a condensate formaldehyde-condensed with the alkali metal salt of para-phenolsulfonic acid and with 4,4'-diphenol sulfone. Here again, the dyed carpet fabric may contain an effective amount of a fluorocarbon intended to improve the soil repellency of the carpet. The preferred amount of fluorocarbon is 0.05 to 0.4 weight percent based on the weight of the fabric. The fluorocarbon may contain a perfluoroalkyl radical or a mixture of fluorinated pyromellitate oligomers. The fluorocarbon may be the reaction product of a perfluoroalkyl alcohol or amide with a suitable anhydride or isocyanate. The fluorocarbon may be the reaction product of N-ethyl perfluorooctylsulfoamide ethanol with toluene diisocyanate. The preferred fluorocarbon is a mixture of pyromellitate oligomers formed by two reactions, namely, first, the reaction of pyromellitic dianhydride with a fluorinated alcohol, and second, the first reaction product is further reacted with epichlorohydrin. The aqueous solution of the second step also contains an effective amount of a thiocyanate such as an ammonium, sodium, potassium, copper, zinc, ferrous, ferric, methyl or phenyl thiocyanate. The preferred thiocyanate is ammonium thiocyanate. The aqueous solution of one or both application steps may also contain an effective amount of a dispersant such as a naphthalene salt, an alkyl sulfosuccinate or a mixture thereof. The preferred dispersant is a Mixture of the sodium salt of condensed naphthalene sulfonic acid and di-isobutyl sulfosuccinate. The aqueous solution from both steps may also contain an effective amount of a salt with a divalent cation, such as a calcium, magnesium or ferrous chloride, sulfate or phosphate, preferably magnesium sulfate. The preferred amounts of this process would be fluorocarbon present in an amount of between 0.05 and 0.4% based on the weight of the fabric, magnesium sulfate present in an amount of between 0.25 and 4% based on the weight of the fabric, ammonium thiocyanate present in an amount between 0.03 and 1% based on the weight of the fabric, the sulfonated aromatic formaldehyde condensate present in an amount between 0.15 and 7.5% based on the weight of the fabric, the dialkyl sulfosuccinate present in an amount between 0 and 6 parts by weight to the parts by weight of the sulfonated aromatic condensate, and the sodium salt of a condensed naphthalene acid present in an amount between 0 and 3 parts by weight to the parts by weight of the sulfonated aromatic condensate. The more preferred amounts are found where the fluorocarbon is present in an amount between 0.05 and 0.4% based on the weight of the fabric, the magnesium sulfate is present in an amount between 0.25 and 1.5% based on the weight of the fabric, ammonium thiocyanate is present in an amount between 0.05 and 0.75% based on the weight of the fabric, the sulfonated aromatic formaldehyde condensate is present in an amount between 0.15 and 2.0% based on the weight of the fabric, and the dialkyl sulfonesuccinate is present in an amount between 0 and 2.5 parts by weight to the parts by weight of the sulfonated aromatic condensate, and the sodium salt of a condensed naphthalene acid is present in an amount between 0 and 2 parts by weight to the parts by weight of the sulfonated aromatic condensate. Here, the aqueous solution can again be buffered with an effective amount of citric acid or any other acid with a sequestering agent to improve the yellowing of the carpet fabric.

The application of the water-soluble thiocyanate to a polyamide fiber is accomplished according to the invention by contacting the fiber with an effective amount of the thiocyanate at a pH between 1 and 5, whereby the fiber has improved resistance to dye fading due to strong oxidizing agents such as benzoyl peroxide or ozone, and wherein the dye may be present in or on the fiber. The thiocyanate may be an ammonium, sodium, potassium, copper, zinc, ferrous, ferric, methyl or phenyl thiocyanate. The preferred pH of the process is between 1 and 4. The preferred amount of thiocyanate is between 0.1 and 6% thiocyanate based on the weight of the fiber present in or on the fiber after dyeing. The process improves the consumption so that between 0.1 and about 12% thiocyanate, based on the weight of the fabric, and at least 50% of the thiocyanate present during contacting is consumed on or into the fiber. The preferred thiocyanate is ammonium thiocyanate. The thiocyanate can be contacted with the fiber in the dye bath or after dyeing. The treated fiber can contain an effective amount of a fluorocarbon to inhibit soiling of the fiber, and a sulfonated aromatic condensate can be present either on the fiber or with the thiocyanate. The various fluorocarbons are as described above. An effective amount of citric acid or any other acid with a sequestering agent can also be used to buffer the condensate and thiocyanate to the desired pH for this same anti-yellowing effect. It is preferred to have between 0.1 and 12% thiocyanate based on the weight of the fabric and between 0.05 and 0.4% fluorocarbon based on the weight of the fabric.

Continuous post-treatment process

This process is intended to continuously treat a nylon carpet fabric with sulfonated aromatic condensate formulations, for example in a continuous dyeing section after steaming but before washing; or piece dyed (or Beck) carpets can be treated continuously in a similar manner by an in-line treatment in the wet-goods drying section before the dryer. The equipment could consist of spray head(s) or equivalent for the heated water above the moving carpet fabric, with vacuum extractors below or a set of nip rolls to remove the water, followed by spray heads for the treating liquid with a catch pan below. An alternative to spray application is the use of a pressure application device such as a Kuster Fluidyer which brings the carpet into contact with a narrow slot in a line containing a pressurized treating liquid.

The prior art describes the application of similar sulfonated aromatic formaldehyde condensates by a Beck's (piecewise) post-treatment and a continuous manner together with dyes and subsequent steaming. The continuous process of this invention has economic advantages over the Beck's post-treatment process of approximately 4 cents per pound of fiber produced as finished carpet (at the same levels of stain release agent on the fiber). The continuous post-treatment process of this invention has the following advantages over the known prior art processes:

(a) Post-staining process.

The process conditions are optimized for the "use up" of the sulfonated aromatic formaldehyde condensate on the fiber. These conditions are not necessarily compatible with the dyeing process. Since the treatment process takes place after dyeing, there is no impairment of the dyeing process. The coexisting state-of-the-art dyeing processes (with dyes) generally lead to poorer dyeing quality, a loss in color yield and the effect of shading the color of the carpet.

(b) More versatile.

The method according to this invention can be used for continuously dyed single-coloured or multi-coloured samples under the same processing conditions. Furthermore, the process can also be used for continuous post-treatment of piece-dyed (or Beck-type) goods in the wet goods dryer.

The process involves the general principle of firstly preheating the carpet with heated water, followed by hydroextraction and application of an aqueous solution of sulfonated aromatic formaldehyde condensate, for which specific pH, concentration, moisture uptake (w/h) and temperature ranges exist. This is followed by a dwell time during which the carpet is either held at temperature or allowed to cool by radiation prior to washing the carpet. Prior to treatment, the carpet has been dyed by either a Beck or continuous process. For Beck dyed carpets, the treatment process takes place in the wet-load dryer and for continuously dyed carpets, the treatment process takes place in-line after steaming and before the final washing step.

Described in more detail, the process involves preheating the dyed carpet with hot water followed by hydroextraction by either squeezing or vacuum techniques to a moisture absorption of 30 to 190%. The conditions of the preheating process are set to achieve a carpet temperature of 130 to 210ºF (54.4 to 99ºC) prior to the treating step. The conditions of the preheating process are generally such that a saturation of 200% w/w to total saturation with water at 140 to 212ºF (60 to 100ºC) is used. As an adjunct in the continuous dyeing process, this provides the carpet with a wash prior to application of the treating solution, which increases the carpet's receptivity to the stain release agent. The treatment solution is an aqueous solution of the sulfonated aromatic condensate at a concentration of 0.25 to 40 grams per liter and a pH from 1.5 to 5.5. The treating solution is applied at an addition rate of 200 to 600% w/w and a temperature of 140 to 212ºF (60 to 100ºC). The resulting temperature of the carpet must be in the range of 130 to 210ºF (54.4 to 99ºC) for the treatment to be effective. It is preferable to minimize the difference in temperature of the carpet fabric between preheating and application. Following application of the treating liquid, it is necessary to either hold the carpet at the application temperature for at least 0.5 to 30 seconds or allow it to cool by radiation to not less than 130ºF (54.4ºC).

The equipment used to apply the treatment liquid may be either of the spray or contact type. The contact method is preferred because it is easier to achieve 100% penetration of the treatment. Spray methods are adequate provided the solution penetrates to the back of the carpet and will generally require additional mechanical considerations, such as squeezing or S-rolling, to achieve complete penetration. Other application equipment may also be used as long as the process requirements of preheating, heating treatment and residence time at temperature are met. The preheating and/or extraction step can be carried out on the pre-existing equipment.

The practical significance of this technique is that it provides an economical and effective means of applying sulfonated aromatic formaldehyde condensates to impart stain resistance to dyed carpets. The process is applicable to over 90% of all carpets treated with sulfonated aromatic formaldehyde condensates.

The continuous post-treatment technique may also be the second step of another embodiment of this invention having a two-step process wherein an effective amount of the sulfonated aromatic condensate is added to a continuous dye bath or in a batch or Beck's process for dyeing carpet fabric. The two-stage process uses a lower total amount of sulfonated aromatic condensate for the same level of stain resistance. Alternatively, the same total amount of sulfonated aromatic condensate can be used in a two-stage process to achieve a higher level of stain resistance.

Certain nylon substrates (fibers) have a very open internal structure (alignment of polymer chains) which require very high amounts of sulfonated aromatic condensate composition to achieve a sufficient level of stain resistance for the market. Certain sulfonated aromatic condensate compositions cannot achieve a sufficient level of protection on these substrates and must therefore be excluded. Also, the continuous post-treatment process results in only moderate durability of the stain resistance properties to steam cleaning when a high pH detergent is used.

The two-step coating process has all the advantages of the continuous post-treatment process, such as economy, etc., over a single-step batch process. It also has unique advantages over the post-treatment process alone and all other continuous coating processes for sulfonated aromatic condensates, such as using all of the sulfonated aromatic condensate in one dye bath (currently practiced on a commercial scale).

The stain resistance level imparted by a given total amount of sulfonated aromatic condensate is substantially improved. The required addition for a marketable stain resistance level is reduced by approximately 30% over post-treatment and even more for other continuous processes, resulting in economic advantages. The process (with an optimized composition of sulfonated aromatic condensate for post-treatment) gives marketable stain resistance levels on the critical substrates described above using of reasonable amounts of the sulfonated aromatic condensate composition. The durability of the stain resistance properties to steam cleaning (with or without a high pH detergent) is reduced compared to the post-treatment only process, resulting in improved properties.

The two-step process involves the general principle of applying a portion of the total sulfonated aromatic condensate composition to be coated in the normal dye bath with an appropriate amount of magnesium sulfate (magnesium sulfate, 0 to 0.35% by weight of fiber for each 1% sulfonated aromatic condensate, based on the weight of fiber). The remainder of the total sulfonated aromatic condensate composition (containing 0 to 0.35% magnesium sulfate) is then applied as a post-treatment. The amount of Epsom salt required in both portions depends on the sulfonated aromatic condensate and the substrate being treated.

The dye bath composition is based on that typically used for continuous dyeing. The appropriate amount of the sulfonated aromatic condensate composition (based on the optimum ratio and total amount required for the particular substrate) is added to the dye bath.

In addition to a sulfonated aromatic condensate, a thiocyanate is added to the formulation, which formulation is used to treat the carpet fabric to eliminate the oxidative yellowing of the sulfonated aromatic condensate and to provide the resulting carpet with better dye resistance to strong oxidizing agents such as ozone or the benzoyl peroxide found in commercial anti-acne preparations. Likewise, a salt containing a divalent cation is useful to improve the absorption of the sulfonated aromatic condensate onto polymer fibers with high ICP. A dispersant(s) is usually required in the formulation to avoid the incompatibility of the components of the formulation with to prevent precipitation or coagulation occurring during treatment and/or the components of a fluorocarbon treated carpet fabric. Acids are used to buffer the formulations. It has been discovered that citric acid or any acid with a sequestering agent provides additional improvement in the yellowing characteristics of sulfonated aromatic condensate treated fibers or fabrics.

Ammonium thiocyanate and sulfonated aromatic condensates are applied to nylon fibers using similar application methods. The two products can be applied together provided that the uptake of one material does not affect that of the other. Therefore, the selection of the sulfonated aromatic condensate is important. Some sulfonated aromatic condensates are preferentially applied via ammonium thiocyanate. But, in contrast, a synergistic effect of Intratex N (reported to be formaldehyde-condensed with an alkali metal salt of a phenol sulfonic acid and with 4,4'-diphenol sulfone) and ammonium thiocyanate was found in benzoyl peroxide stain resistance.

An additional benefit of ammonium thiocyanate in the composition is as an antioxidant to prevent light-induced yellowing of Intratex N . This combination was found to give sufficient improvement (acceptable lightfastness) for Beck applications, but was insufficient (although improved) for continuous applications.

The combination of sequestering agents such as EDTA and sodium hexametaphosphate with Intratex N was found to give some improvement in light-induced yellowing, but did not give fully acceptable results for continuous application. The combination of Intratex N with citric acid (sequestering and antioxidant properties) also gave similar results. The combination of ammonium thiocyanate and citric acid was found to give the best results in reducing light-induced yellowing for continuous application as it virtually eliminated yellowing. (Combinations of ammonium thiocyanate and other sequestrants were not as effective.)

A new dispersing system using Tamol SN and Monawet MB-45 was developed to produce a stable composition containing Intratex N, ammonium thiocyanate and citric acid in concentrated form for continuous applications. A new dispersing system was developed to produce a stable concentrate containing Intratex N and ammonium thiocyanate for Beck applications. Example Compositions Ingredient Composition % Solids % Intratex N* (sac) Intratex N-1* Ammonium thiocyanate Citric acid (50% solution) Sulfuric acid Tamol SN (sodium salt of condensed naphthalene sulfonic acid) Monawet MB-45 (di-isobutyl sulfosuccinate) Epsom salt (magnesium sulfate) Demineralized water * Same concentration of the same sac, N-1 has a pH of 7, N has a pH of 10.5.

Any thiocyanate such as those listed above is expected to be effective, although the copper, ferrous and ferric thiocyanates may need to be color compensated.

Any effective agent can be used as the dispersant, such as, for any process formulation, the condensed naphthalene salts, the alkyl sulfosuccinates and a mixture thereof, and for batch process systems, salts of a polymeric carboxylic acid and polyethylene glycol ether.

The sequestering agents expected to be effective are the polyphosphates such as sodium tripolyphosphate (STPP), aminocarboxylic acids such as ethylenediaminetetraacetic acid (EDTA), hydroxycarboxylic acids such as tartaric acid and citric acid, and the aminoalcohols such as triethanolamine (TEA). See Kirk-Othmer Encyclopedia of Chemical Technology, supra.

example 1

On a commercial dye line, Composition 1 was applied to a carpet fabric containing a normal and a high ICP fiber in both a two-stage (continuous-continuous) and a continuous-only post-treatment process. The normal fiber was in a 132 tex (1186 denier) Superba heat-set textured yarn. The high ICP fiber was a 189 tex (1700 denier) textured yarn that was heat-set using a proprietary high heat history Pharr process, giving an ICP of 3.92 compared to a normal ICP of approximately 3.8. Both fibers had been previously treated with a spin finish containing a soil release fluorocarbon as described in US-A-4,604,316 and/or US-A-4,192,754. The fabric was dyed grey. The prewash and treatment application took place immediately after the dryer but before the final wash on the continuous dyeing line by spraying. The following are the dyes and chemicals used in the continuous dye bath.

Control test:

0.135 g/l** Nylanthrene¹ Orange RAR (liquid)

0.092 g/l Tectilon² Red 2B Liquid-50

0.052 g/l Telon³ Blue B-AR (powder)

(the dyes above are the same for all dye baths.)

3.0 g/l Alrowet² D-70*

1.0 g/l Chemcogen⁴ DCG*

0.5 g/l Defoamer AC (Fuller)*

pH 5.5 with acetic acid

400% w/w via a Kuster Fluidyer

Steam in the vertical steamer for 5 to 6 minutes

"4% dye bath":

(Order of addition to the bath as listed.)

3.0 g/l Alrowet D-70

1.0 g/l Chemcogen DCG

0.5 g/l Defoamer AC (Fuller)

10.0 g/l Composition 1

1.25 g/l Epsom salt (magnesium sulfate)

0.5 g/l Seguestrene2 30A*

The above dyes

Approximately 1 g/l ammonia to a pH of 5.5

"8% dye bath":

(Order of addition to the bath as listed.)

3.0 g/l Alrowet D-70

1.0 g/l Chemcogen DCG

0.5 g/l Defoamer AC (Fuller)

20.0 g/l Composition 1

2.5 g/l Epsom salt (magnesium sulfate)

0.5 g/l Sequestrene 30A*

The above dyes

Approximately 3 g/l ammonia to a pH of 5.5

* Alrowet D-70 is dioctyl sulfosuccinate - 70% active

Chemcogen DCG is sulfonated alkyl diphenyl ether - 30-38% active.

Defoamer AC is a proprietary defoamer from Fuller Sales.

Sequestrene 30A is ethylenediaminetetraacetic acid

1 (TM) by Crompton % Knowles

2 (TM) by Ciba Geigy

3 (TM) by Mobay

4 (TM) from Lyndal Chem.

** Grams per liter

The following tables provide alternative operating conditions and results using the above dye baths and post-treatments shown. Runs 3 and 4 were omitted because they contained a slightly different, non-preferred formulation. TABLE I Post-Treatment (A/T) Job Data Preheat Fluid Temperature Test ID* Nomin. Addition/Combination1 from Dye Bath %Wt/Fas. Nomin. Addition/Combination1 from A/T %Wt.Fas. Nomin. Total Addition/Combination1 %Wt/Fas. TABLE I (CONTINUED) Post-Treatment (A/T) Application Data Carpet Temperature Before A/T Carpet Temperature After A/T Test ID* A/T Fluid pH

* Experiments numbers 1, 5, 9 and 10 are regular carpet; the remaining numbers are high ICP carpet. Experiments 1 and 2 are controls.

Both fabrics are cut pile with 1356 g/m² (40 oz/sq yd).

The A/T fluid temperature ranged from 82.2-83.3ºC (180- 182ºF) TABLE II SOLUTION AND CARPET ANALYSIS DATA Test ID Nomin. Addition of Target Comp. 1 %wt. Nomin. Conc. of Comp. 1 in Dye Bath g/L Anal. of Conc./Nomin. Comp. 1 in Dye Bath g/L Calc. Addition/Comp. 1 from Analysis %wt. TABLE II (CONTINUED) SOLUTION AND CARPET ANALYSIS DATA Post-Treatment Section Test ID Nominal Target Addition %wt.Fas. Feed Conc. GPM* l/m Actual Pressure at A/T Spray Head psig/kPa Total A/T Fluid Feed GPM* l/m

The linear velocity for both materials was 30 ft/min./9.1 m/min-1.

Throughput = 45.3 kg (99.8 lb) carpet/min.

The actual ink moisture absorption was 400% in all cases.

The post-treatment moisture uptake was always between 626 and 643%.

The post-treatment pH was always 2.8 and 3.0, except for the control experiment where it was 7.6.

* Gallons per minute TABLE II (CONTINUED) SOLUTION AND CARPET ANALYSIS DATA Post-Treatment Section Test ID Calc Nomin. A/T Fluid Conc. g/L Anal. A/T Fluid Conc. g/L Calc Add/Combination 1 from Equipment %Wt.Fas. Calc Add/Combination 1 from Analysis %Wt.Fas. TABLE II (CONTINUED) SOLUTION AND CARPET ANALYSIS DATA Concurrent and Post-Treatment Portion Trial ID Addition Target Comp 1 %WtFas Calc Addition Comp 1 from Equipment %WtFas Calc Addition Comp 1 from ANALYSIS %WtFas Anal Addition Comp 1 from Carpets %WtFas Anal Addition sac from Carpets %WtFas

The linear velocity for both materials was 30 ft/min//9.1 m/min.

Throughput = 45.3 kg (99.8 lb) carpet/min.

The actual ink moisture absorption was 400% in all cases.

The post-treatment moisture uptake was always between 626 and 643%.

The post-treatment pH was always between 2.8 and 3.0, except for the control experiment where it was 7.6. TABLE III STAIN DATA Test ID Nomin. Addition Com. 1 from dye bath % wt.fas. Nomin. Addition Com. 1 from A/T, % wt.fas. Total Nomin. Addition Com. 1 % wt.fas. Stain Rating¹ (0=best 10=worst) Time before water quenching in hours Original After

* Steam cleaning

2 passes of detergent solution using conventional steam cleaning equipment. Detergent solution: 7.49 kg/m3 (1 oz./gal). ALL-IN-ONE (Certified Chemical & Equipment, Cleveland, OH).

¹ See Example 6, Part 2, "Performance", "Drip Test" TABLE IV REJECTION AND COLOUR FASTNESS DATA Rejection³ Test ID Addition Composition 1 from dye bath %wt.fas. Addition Composition 1 from A/T %wt.fas. Total Nomin. Addition Composition 1 %wt.fas. Oil Water Grey Scale Rating Light Fastness Ozone Fastness¹ NO₂² Fastness 1 cy**

* AATCC 16 E Fade Unit

** Cycles

¹ AATCC129

² AATCC164

³ Oil repellency

- AATCC TM-118, Oil Repellency: Hydrocarbon Resistance Test.

Water repellency

DuPont Series - Isopropanol/Water

1. 2/98 IPA/Water (55)

2. 5/95 IPA/water (47)

3. 10/90 IPA/water (40)

4. 20/80 IPA/water (33)

5. 30/70 IPA/water (28)

The numbers in brackets represent the surface tension of the test liquids. TABLE V STAIN DATA WITH BENZOYL PEROXIDE* Stain Visibility 0=invisible; 10=light Benzoyl Peroxide Concentration % Solution in Acetone Test ID Addition Composition1 from Dye Bath %.Wt.Fas. Addition Composition1 from A/T %.Wt.Fas. Total Addition Nomin. Average %.Wt.Fas.

* A sample stained with 1 ml of benzoyl peroxide solution and exposed to a chamber at 90ºF (32.2ºC) and 80% RH for three days (color change ceases). TABLE VI STAIN DATA Stain Rating (0=best, 10=worst) Outsoles Grade Method Test ID Addition Composition1 from dye bath %wt.fas. Addition Composition1 from A/T %wt.fas. Total Addition Nomin. Composition1 %wt.fas. Total Stain Rating

* Accelerated pollution carried out at the Petersburg Rehabilitation Center using "natural dirt" with an addition of 2.5% mineral oil.

**John Tyler Community College Maintenance Hall.

Example 1 - Conclusions

The two-step composition process provides significantly better stain resistance than the post-treatment (only) process at the same total add-on levels. This indicates a potential to achieve acceptable performance at lower total add-on levels.

The two-step process also provides acceptable stain resistance on the "high ICP" substrate at levels comparable to those currently used for normal s.a.c. substrates for post-treatment alone.

Stain resistance is improved with increasing concentration of Composition 1 in the concurrent part and light fastness is adversely affected (yellowing) while the total addition level remains the same. Acceptable yellowing and stain resistance was achieved at 4% of Composition 1 in the concurrent part based on the weight of the fiber.

"Optimal" two-stage systems exhibited improved stain resistance properties to ozone and benzoyl peroxide (B.P.). Some reduction occurs when the concentration applied in the post-treatment part is reduced in favor of the simultaneous part.

Example 1 - Summary of results Stain performance table III:

In general, a standard heat set (H/S) Superba substrate performs better than the high ICP substrate under equivalent deposition conditions, while the analyzed add-ons remain the same. This is usually observed due to undesirable deep penetration of s.a.c. into the high ICP fiber.

When Composition 1 was applied to the high ICP fiber with only a post-treatment, it did not provide acceptable stain performance. When the amount of Composition 1 was increased from 11 to 15% of the high ICP fabric based on the weight of the fiber, stain resistance was further improved to a "marginal" level of performance (stain rating of 1.5 at 4 and 24 hour wipe times).

The two-step process gave significantly better stain resistance than the post-treatment only process at equivalent total application rates on both substrates. No stain was obtained for 24 hours on the Superba H/S fabric using 4% in the dye bath based on the weight of fiber and 7% based on the weight of fiber in the A/T. The same amounts of high ICP substrate gave stain performance equivalent to that of the Superba fabric post-treated (only) with 11% of Composition 1 based on the weight of fiber (stain rating 0.5 for 24 hours).

Example 1 - Summary of results Colour fastness table IV:

At 20 AFU, no light-induced yellowing was observed in any of the experiments performed, but at 40 AFU, it began to be observed.

Light-induced yellowing (at 40 AFU) was more easily detected with increasing levels in the co-part (and with reduced post-treatment). Trials with 8% of Composition 1, based on the weight of fiber, in the co-part (high ICP substrate) were marginal to unacceptable for lightfastness.

The improvement in resistance to ozone fading achieved with Composition 1 by post-treatment was also observed for Composition 1 using the two-step process with Composition 1 (at a lower level).

Table V (Benzoyl peroxide staining):

The two-stage process resulted in only a slight reduction in stain removal performance with benzoyl peroxide compared to the post-treatment process when the amounts added were the same.

Table IV (Rejection):

There was no significant effect on oil and water repellency in any of the tests. As the amount of composition 1 (and magnesium sulfate) in the same part increased, the oil repellency tended to decrease slightly.

Table VI (Soiling)

In all test samples, only a slightly negative effect on soiling was observed compared to the control test.

Composition 1 showed a slightly increased soiling when the applied concentration was increased when applied by post-treatment.

At a constant total addition, the two-stage process had a less significant impact on the contamination than was the case with post-treatment alone.

Guidelines for a two-step process (best way) for continuous application of composition 1 simultaneous part (with the dyes) :

For Suessen H/S substrates: 2.0% w/w.

For Superba H/S substrates: 3.0% w/w

For substrates with "high ICP" 4.0-5.0% wt./fas.

Dye bath assembly process:

1. Humidifying and leveling agents (defoamers, if necessary)

2. Composition and Epsom salt** (MgSO₄-7H₂O) (0.5% w/w Epsom salt for every 4.0% w/w of Composition 1)

3. 0.25-0.50 g/l sequestrant (EDTA)

4. Dyes

5. Adjust the desired pH value either with acetic acid, ammonia or caustic soda*

Remarks:

* Composition 1 has a low pH. Its use in the dye bath will result in a pH of 3.0-3.5, requiring an alkali to adjust the pH.

** In the presence of magnesium sulfate, only phosphates that form water-soluble complexes with magnesium ions can be used.

Aftercare part: Concentration of composition 1:

For Suessen H/S substrates: 3.0% w/w.

For Superba H/S substrates: 5.0% w/w

For substrates with "high ICP" 7.0-8.0% wt./fas.

Application parameters:

Preheat and wash spray at 160ºF (71.1ºC) and extract (vacuum) to 75-125 wt%/unit to achieve a carpet temperature of 140ºF (60ºC).

Apply a treatment solution at 180ºF (81.2ºC) and 400-500 wt%/unit to give a post-A/T carpet temperature of 160ºF (71.1ºC).

Example 2

This is another example of the continuous post-treatment process of the invention using Composition 2 in the treatment of the carpet fabric. The fabrics treated were (a) a fabric tufted from a 132 tex (1186 denier) continuous filament textured half-dyed yarn in a heat set (H/S) Superba yarn to a 0.79 kg cut pile fabric and (b) a No. 3.15/2 cotton textured yarn made from a deep dyed staple fiber of 2.1 tex (19 denier) per filament heated in a steamer and tufted to a 1.36 kg (48 ounce) fabric. Both were pretreated with the fluorocarbon of Example 1 and were to be dyed light gray. The nominal application conditions were 60ºC (140ºF) preheat water temperature, a coating fluid temperature of 81.2ºC (180ºF), 500 to 600 wt.%/unit of coating fluid, the dyes and dye bath additives were as in Example 1 except that no Sequestrene was used. No Composition 2 or other sac was added to the dye bath. The following tables show the application conditions and the results. TABLE VII APPLICATION DATA Test ID Nomin. Applied Total2 % Nomin. Target Sac Rate %Wt.Fas. Nomin. Target Epsom Salt Rate %Wt.Fas. Actual A/T Spray Head Pressure psig A/T Fluid Delivery GPM Applied A/T Fluid Concent. g/L

The actual wt/unit were between 523 and 532%, the pH was 8.3 for the control, 3.0 for Trial 2, 3.3 for Trial 4.

The preheat fluid temperature was 60ºC (140ºF). The carpet temperature was 52.8-54.4ºC (127-130ºF). The application fluid temperature was 81.7-83.5ºC (179-182ºF), and the carpet temperature was 68.9-71.7ºC (156-161ºF). TABLE VII (CONTINUED) APPLICATION DATA Trial ID Calculated Addition/Add. 2 From Facility %Wt.Fas. Calculated Sac Addition From Facility %Wt.Fas. Calculated Sac Addition From Anal. Of A/T Fluid %Wt.Fas. Anal. Sac Addition From Carpet %Wt.Fas. Calculated Epsom Salt Addition %Wt.F

The actual wt/unit were between 523 and 532%, the pH was 8.3 for the control, 3.0 for trial 2, 3.3 for trial 4.

The preheat fluid temperature was 140ºF (60ºF). The carpet temperature was 127-130ºF (52.8-54.4ºC). The application fluid temperature was 179-182ºF (81.2-83.3ºC), and the carpet temperature was 156-161ºF (68.9-71.7ºC). TABLE VIII STAIN PERFORMANCE, STEAM CLEANING AND DISCOLORATION DATA Stain Rating (0=best, 10 worst) Time before water blot in hours Sample ID Nomin. Applied Total2% Time before water blot in hours Color Change

* N=none, acceptable; M=marginal; Y=yellow. The letter in parentheses indicates the direction of the color change from the control.

** steam cleaned TABLE IX COLOUR FASTNESS DATA Grey Scale Rating Light Fastness, AFU Sample ID Nomin. total 2 in % Grayscale evaluation Sample ID Ozone fastness NO₂* fastness 1 cy

* High RH Nitrogen Dioxide (AATCC TM-164). TABLE X STAIN DATA WITH BENZOYL PEROXIDE* Stain Visibility (0=invisible, 10=light) Original Benzoyl Peroxide Concentration Solution % in Acetone Sample ID Nomin. Applied Total 2%

* Sample stained with 1 ml of benzoyl peroxide solution and exposed to a chamber at 90ºF (32.2ºC) and 80% RH for three days (discoloration ceases). TABLE X (CONTINUED) BENZOYL PEROXIDE STAIN DATA* Stain Visibility (0=invisible, 10=light) Steam Cleaned Benzoyl Peroxide Concentration Solution % in Acetone Sample ID

* Sample stained with 1 ml of benzoyl peroxide solution and placed in a chamber at 90ºF (32.2ºC) and 80% RH for three days (discoloration ceases). TABLE XI REJECTION DATA (FINISHED CARPETS) Rejection Sample ID Nomin. Applied Composition 2 in % Oil Water

This Example 2 demonstrates the effectiveness of sulfonated aromatic condensate with only a dispersant and further illustrates the effectiveness of the continuous post-treatment process of this invention.

Example 3 - Part 1

This example demonstrates the effective use of the process of this invention on fabric that has not been previously treated with any fluorocarbon compound for soil release properties. Composition 2 used in the continuous (not two-stage) post-treatment process of this invention is shown in the example. The dye bath formulation was the same as in Example 2. The conditions were the same as in Example 1, specifically, the preheat water temperature was 195°F (90.6°C) at 100 wt%/unit to achieve a carpet temperature of 135-140°F (57.2-60°C). The post-treatment liquid temperature was 180-185°F (82.2-85°C) to achieve a carpet temperature of 160-170°F (71.1-76.7°C). The post-treatment dwell time was 30 seconds prior to washing at a 40:1 liquid to fabric ratio, and prior to hydroextraction and drying. Both compositions were applied at both 1.5 and 3.0% based on the weight of the fiber. Samples of the fluorocarbon pretreated fabric, which fluorocarbons are also part of this invention, were run along with the non-fluorocarbon treated fabric. The results show that higher levels of sulfonated aromatic condensate must be applied to the non-fluorocarbon treated fabric to achieve nearly the same stain resistance value. The following tables show the application conditions and results. TABLE XII STAIN INHIBITION RATING FOR CONTINUOUS AFTER-TREATMENT Total Stain Rating¹ 20 AFU Class² Sample ID Nominal Addition % * Fabric with Fluork. Fabric without Fluork.

* Samples 2 and 4 were applied at pH 3. Samples 1 and 3 were applied at pH 2.

¹ Overall scores from 1-, 4-, 7- and 24-hour tests. High numbers indicate the heaviest stains.

² Lower numbers are better. TABLE XII (CONTINUED) STAIN RESISTANCE RATING FOR CONTINUOUS POST-TREATMENT NO₂ Class² Soil Rating** Sample ID Fabric with Fluorocarbon Fabric without Fluorocarbon

** Soiling evaluated using accelerated method, 0=best, 10=worst.

² Lower numbers are better. TABLE XIII ANALYSIS DATA Sac's analyzed, % wt.fas.* Sample ID Nomin. Addition, % Material with fluorocarbon Material without fluorocarbon

Samples 2 and 4 were applied at a pH of 3.

Samples 1 and 3 were applied at a pH of 2.

* Extracted from carpets with 0.1N NaOH for four hours and analyzed by HPLC against the original material.

Example 3 - Part 2

The conditions of Example 3 - Part 1 were repeated except that Composition 1 was used with the results shown in the following tables. All fabrics were without fluorocarbon treatment. TABLE XIV STAIN AND COLOUR CHANGE DATA Stain Rating (0=best, 10=worst) Time before water blot in hours Sample ID Nomin. Addition of Compound 1% w/w Colour Change TABLE XV COLOUR FASTNESS DATA Greyscale Rating Light Fastness, AFU Ozone Fastness, cy NO₂* Fastness, cy Sample ID Nominal addition of composition 1% by weight. TABLE XVI ANALYSIS DATA Test ID Nomin. Addition Composition 1 %wt.fas. Nomin. Conc. of A/T Fluid from Composition 1 g/l* Anal. Conc. of A/T Fluid from sac g/l Sac Addition Based on Anal. of A/T Fluid %wt.fas. Anal.. Sac Addition from Carpets %wt.fas Anal. sac in Rinse Bath g/l

* Applied at 400 wt%

** Not recorded

Example 4

The procedure and conditions of the dye formulations of Example 2 were repeated using Composition 2 with and without citric acid to adjust the pH in the continuous application process of the post-treatment of this invention, the fabric being a 1.08 kg/m² (32 ounces per square yard) cut pile construction of bulked Superba H/S 131.7 tex (1185 denier) continuous filament dyed gray by the Beck process. The fiber had been treated with fluorocarbon for soil release properties. Also, for another set of samples, all dispersants (Tamol) were omitted from Composition 2. Epsom salt (49% MgSO₄) was added to another set of samples. Citric acid was used as the rinse liquid and in the application liquid. The use of citric acid in the treatment liquid or to adjust the pH resulted in an improvement in the yellowing of the fiber treated with sulfonated aromatic condensate. The combination of Epsom salt and citric acid further reduced the tendency toward yellowing, whether due to exposure to ozone or NO₂. The following tables show the application conditions and the results. TABLE XVII EVALUATION OF CITRIC ACID - USE FOR CONCENTRATION OF PH ADJUSTMENT ON LIGHT-INDUCED YELLOWING APPLICATION AND ANALYSIS DATA Test ID Nomin. applied sac % Others/Conc. untreated Composition Intratex N Citric Acid Citric Acid (adjusted pH)* 0.72 wt%/Fas. Epsom Salt & Citric Acid (adjusted pH)*

* 1.25 g/l citric acid required to adjust the pH value. TABLE XVII (CONTINUED) EVALUATION OF CITRIC ACID - USE FOR CONCENTRATION OF PH ADJUSTMENT FOR LIGHT-INDUCED YELLOWING APPLICATION AND ANALYSIS DATA Test ID Use pH Rinse Fluid Analyzed sac % Normal - cold water Citric Acid (pH) No Rinse Fluid

Remarks:

The carpet temperature before A/T was in the range of 132 to 138ºF (55.6-58.9ºC).

The A/T fluid temperature was 183 to 185ºF (83.9-85ºC).

The actual temperature after A/T ranged from 163 to 171ºF (72.8-77.2ºC). TABLE XVIII EVALUATION OF CITRIC ACID - USE TO CONCENTRATE PH ADJUSTMENT ON LIGHT INDUCED YELLOWING STAIN PERFORMANCE AND COLOR CHANGE DATA Stain Rating (0=best. 10=worst.) Time before water erasure in hours Test ID Color Change

* M=marginal, N=none, Y=yellow, b=blue TABLE XIX EVALUATION OF CITRIC ACID - USE FOR CONCENTRATION OF PH ADJUSTMENT ON LIGHT-INDUCED YELLOWING COLOR FASTNESS DATA Gray Scale Rating Light Fastness AFU Ozone Fastness, cy NO₂* Fastness 1 cy Sample ID

* Nitrogen dioxide with high relative humidity (AATCC TM-164). TABLE XX EVALUATION OF CITRIC ACID - USE FOR CONCENTRATION OF PH ADJUSTMENT ON LIGHT-INDUCED YELLOWING STAIN DATA WITH BENZOYL PEROXIDE Stain Visibility (0=invisible. 10=light) Benzoyl Peroxide Conc., Solution % in Acetone Sample ID

* Sample stained with 1 ml of benzoyl peroxide solution and exposed to a chamber at 90ºF (32.2ºC) and 80% RH for three days.

Example 5

The procedure was repeated on the material of Example 4, using also Composition 2 with and without the dispersant Tamol and also adding NH₄SCN to demonstrate its advantages.

The following are the post-treatment conditions used in the standard continuous process:

Prewash/heat carpet at 195ºF (90.6ºC) and 100% w/w to achieve a carpet temperature of 135 to 140ºF (57.2 to 60ºC) prior to treatment.

Apply an A/T liquid at 400 wt%/unit and 175 to 180ºF (79.4 to 82.2ºC) to achieve a post-A/T carpet temperature of 160 to 170ºF (71.1 to 76.7ºC).

Post-treatment, 30-second dwell time before washing (at a liquid ratio of 40:1), hydroextraction and drying.

Summary of results: 1. Application

It was found that the addition of NH₄SCN to the bath of composition 2 affected the pH only at the lowest concentration. This is an indication of the Ability of solutions with composition 2 to buffer.

During the preparation and operation of the treatment solutions, it was observed that with Intratex N alone, considerably more foaming occurs than with composition 2.

2. Stain resistance

Composition 2 tends to provide better stain removal performance than comparable amounts of Intratex N alone. The differences between the two diminish with increasing total concentration.

The addition of NH4SCN did not adversely affect stain performance and, in fact, samples with NH4SCN tended to perform better than corresponding samples without NH4SCN. The difference decreases as the concentration of Intratex N increases and overall performance increases.

3. Light and NO2-induced yellowing (Table XXIII)

It was found that Intratex N and Tamol SN (individually) behaved differently when exposed to light. Intratex N takes on a strong yellow/brown tint when exposed for short periods (20 AFU). This yellow or brown discoloration then fades when exposure is continued for lightfastness. On the other hand, Tamol turns greenish when exposed to 20 AFU and with continued exposure the green fades to yellow. The overall color change rating does not necessarily improve with exposures of 20 to 40 AFU. The intensity of the color change is approximately equal to that of Intratex N and Tamol SN.

The breakthrough of Composition 2 at short exposures for lightfastness (20 AFU) appears as a hybrid blend of Intratex N and Tamol SN alone (at the respective amounts of Composition 2).

At both 20 and 40 AFU, the breakthrough of the samples with composition 2 was no worse to slightly better than the corresponding samples with Intratex N and Tamol SN alone.

The addition of NH4SCN results in a slight improvement in light-induced yellowing. The reduction is greatest at the lower levels of Intratex N and decreases with increasing levels of Intratex N. A similar behavior is observed between Composition 2 and Intratex N alone, but Tamol SN is less affected.

The yellowing decreases with increasing NH₄SCN content. The yellowing decreases significantly when using approximately 0.3 wt.%/fas. NH₄SCN for each 1.0 wt.%/fas. Intratex N.

Tamol SN was found to be unaffected by exposure to NO₂, whereas composition 2 and Intratex N turned an intense yellow. The addition of NH₄SCN only slightly improved the yellowing by NO₂, but not enough to raise the grey scale ratings above 1-2.

4. Ozone fastness (Table XXIII)

Intratex N had a significant impact on ozone fastness, both alone and as a composition 2. While overall fastness ratings tended to be better compared to the untreated control with longer cycles, significant yellowing occurred.

The yellowing of Intratex N overwhelms any improvement achieved by the addition of NH4SCN. The samples containing NH4SCN tend to yellow less when exposed to ozone, with higher levels giving a greater improvement. The significant improvement in ozone fastness by NH4SCN alone was not achieved, but was improved over untreated samples.

5. Staining with benzoyl peroxide (Table XXIV)

The Tamol SN dispersant had no effect on the benzoyl peroxide stain performance. Table XXIV shows identical performance with benzoyl peroxide when 0.3 wt%/fas. NH4SCN is applied either with Composition 2 or with the s.a.c. at multiple levels.

The performance of NH₄SCN is not affected at different sac levels (as composition 2 or alone), as shown in Table XXIV.

Benzoyl peroxide staining improves as the NH4SCN concentration is increased from 0.3 to 0.6 wt%/fas. This improvement becomes even more noticeable at the highest benzoyl peroxide concentration and probably beyond.

Conclusions

Dispersant SN contributes to the light-induced yellowing of the composition, but is not the only cause. Elimination of Tamol SN from Composition 2 would not significantly improve or resolve yellowing on Superba H/S substrates. Elimination of Tamol SN could slightly reduce stain performance at lower additions and increase foaming of the treatment fluid during spray application.

Intratex N is the only cause of yellowing when composition 2 is exposed to ozone.

Tamol does not interfere with any benefit provided by NH4SCN.

Intratex N has a significant impact on ozone fastness (it yellows) and overcomes the ozone fastness improvement benefits achieved by NH4SCN. However, at nominal 0.6 wt%/fas. NH4SCN there is a reduction in yellowing and an improvement over composition 2 alone.

NH4SCN has no adverse effect on the stain inhibiting benefits of the composition.

There is a reduction in light-induced yellowing when NH4SCN is applied with Composition 2. The degree of improvement varied from marginal to significant during all internal trials. Higher amounts of NH4SCN always result in greater improvement.

Benzoyl peroxide stain performance can be further improved, especially at higher benzoyl peroxide concentrations, by increasing the NH4SCN level to 0.6 wt%/fas. TABLE XXI APPLICATION AND ANALYSIS DATA Sample ID As Sum 2 Applied Nominal Sac % Nominal Applied Sac % Nominal Applied Tamol SN % pH Sac Analysis (As Applied) %

* Materials as supplied, unmixed or applied as part of a composition.

Remarks:

Carpet temperature before A/T ranged from 132 to 144ºF (55.6-62.2ºC).

The A/T fluid temperature was 178 to 183ºF (55.6-62.2ºC).

The actual temperature after A/T ranged from 158 to 172ºF (70-77.8ºC). TABLE XXII STAIN PERFORMANCE DATA Stain Rating (0=best 10=worst) Time before water removal in hours Sample ID TABLE XXIII LIGHT FASTNESS DATA Gray Scale Rating Light Fastness AFU Ozone Fastness, cy Sample ID NO₂* Fastness 1 cy

* Nitrogen dioxide with high relative humidity (AATCC TM-164). TABLE XXIV STAIN DATA WITH BENZOYL PEROXIDE* Stain Visibility (0=invisible 10=light) Benzoyl Peroxide Conc., Solution % in Acetone Sample ID

* Sample stained with 1 ml of benzoyl peroxide solution and exposed to a chamber at 90ºF (32.2ºC) and 80% RH for three days.

Example 6

This example illustrates the charge-charge (Beck-Beck) process technique in two steps.

The prior art has shown that applying sulfonated aromatic condensates (stain inhibitors) to nylon improves stain resistance from most food dyes. In the prior art, the preferred method of application was to treat with the stain inhibitor after dyeing was completed at low temperature (48.9 to 82.2°C (120 to 180°F). The prior art also includes applying stain inhibitors simultaneously with dyeing. This invention involves applying a portion of the total stain inhibitor simultaneously with dyeing, and applying the remainder in a low temperature post-treatment step (two-step process).

The two-step process results in a level of stain performance that is superior to that achieved by the prior art at the same total addition concentration of a stain inhibitor. In addition, the use of ammonium thiocyanate in the post-treatment step improves color fastness to ozone, benzoyl peroxide (acne medications) and light.

It is theorized that the improvement over the prior art is achieved by maximizing the concentration of the stain inhibitor in a thin zone near the fiber surface and that this condition results in better stain resistance. The two-step process promotes this condition by sorbing a portion of the stain inhibitor during the dyeing operation that fully penetrates the cross-section of the nylon fiber. The sorption of the portion of stain inhibitor that is subsequently applied in the low temperature post-treatment step is retarded by the presence of the portion already present on the fiber, thus increasing the effective concentration near the fiber surface. The presence of magnesium sulfate in both process steps accelerates the rate of sorption of the stain inhibitor by increasing the electrolyte concentration. of the bath and by forming complexes with the stain inhibitors, thereby reducing molecular mobility in the nylon.

Example 6 - Part 1 (Comparison example)

This example shows that the two-stage procedure is superior to both simultaneous and follow-up treatment.

Carpet material:

131.7 tex (1185 denier) fluorocarbon treated Superba Heat Set.

Procedure:

A total amount of 2.0 wt.%/fas. Intratex N was applied to the carpet.

This total amount was distributed between the dye bath and the post-treatment in the following ways. Dye bath, % Post-treatment, %

Varying amounts of magnesium sulfate were used (0 wt.%/fas. to 4 wt.%/fas.).

The dye bath conditions were typical for industrial practice.

The dyeing process was as follows:

1. Load and pre-wet the fabric at a liquid ratio of 20:1.

2. Add 1 wt.%/fas. Dowfax 2Al sodium mono- and didodecyl disulfonated diphenyl oxide (45% active)

3. Add the specified amount of Intratex N-1

4. Add the specified amount of magnesium sulfate

5. Operate for 5 minutes

6. Add 5% Sequestrene 30A (EDTA) or some equiv.

7. Add 1 wt.%/fat ammonium sulfate

8. Add 0.5 wt./fas.% ammonium hydroxide

9. Addition of pre-dissolved dyes

10. Operate for 10 minutes

11. Bring temperature to boiling point

12. Simmer for 30 minutes

13. Apply and rinse with cold water

14. Follow-up treatment if indicated

The post-treatment process is as follows:

1. Refill Beck at a fluid ratio of 20:1

2. Add a specified amount of magnesium sulfate

3. Add a specified amount of Intratex N1

4. Operate for 10 minutes

5. Lower the pH to 2.0 to 2.1 with sulfamic acid

6. Increase temperature to 71.1ºC (160ºF)

7. Keep at temperature for 20 minutes

8. Skip the bath and rinse with cold water

Perfomance:

Reference samples Nos. 17 to 31 in Table XXV. Samples 23, 24 and 25 prepared by the two-stage 50%/50% process are superior. Those samples that passed the immersion test were further tested by the drop test.

Test protocols:

1. "Dip Test" - Immerse a 5 gram sample of unfinished carpet in a large excess of Cherry Kool-Aid (unsweetened) for 30 minutes at room temperature. Rinse with cold water, dry and evaluate the stain.

2. "Drop Test" - Drop 30 ml of "Cherry Kool-Aid" (unsweetened) from a height of 30.5 cm (12 inches) onto the treated carpet. Allow to stand for seven hours. Using water spray with paper towels-¹ registered by General Food Corporation to assist in the removal.

Example 6 - Part 2

This example demonstrates the use of ammonium thiocyanate in a two-step process for improved resistance to benzoyl peroxide and photofading.

Carpet material:

188.9 tex (1700 Denier) Superba Heat Set (high ICP fiber)

Procedure:

Using the procedure of Part 1, a total of 2.8% Intratex N was applied using a two-step 50%/50% process. A second sample was prepared in the same way but using a mixture containing ammonium thiocyanate (Composition 3) pre-formulated with Intratex N in the post-treatment step. Composition 3 consists of 40% Intratex N-1, 12% ammonium thiocyanate, 21.5% Monawet MB45 and 26.5% water.

Perfomance:

Reference samples "H" and "I" in Tables XXVI to XXVIII. Using the "Drip Test" protocol of Example 1, sample "I" has good stain resistance (slightly worse than "H"), but very significant improvements in benzoyl peroxide and photofading.

Example 6 - Part 3

This example shows that the two-stage 50%/50% process is preferred and that 2% magnesium sulfate is optimal.

Carpet fabric

A fluorocarbon autoclaved heat-set yarn of 131.7 tex (1185 denier) (high ICP fiber)

Procedure:

Using the procedure of Part 1, a total of 3.0% Intratex N-1 was applied using the two-step procedure.

The total amount was distributed between the dye bath and the post-treatment in the following ways: Dye bath, % Post-treatment, %

Varying amounts of magnesium sulfate were used (0 wt.%/fas. to 4 wt.%/fas.).

Perfomance:

Reference Samples 2 to 23 Table XXIX. Using the test protocols of Example 1, Samples 20 to 23 (50%/50% application method) have the best stain resistance. Sample 20 is the best of the group (using 2% and 2% w/w magnesium sulfate). TABLE XXV Dye bath post-treatment K/A** immersion test ***

* Epsom salt

** Kool-Aid

*** F=failed P=passed S=light stain TABLE XXV (CONTINUED) Dye Bath Post-Treatment K/A Dip Test

P = passed (no stain)

F = failed (noticeably discolored)

S = light stain (just noticeable)

* Epsom salt TABLE XXV (CONTINUED) Gray Scale 7-Hour Kool-Aid Stain* Fastness to Xenon Light 20 AFU Color Change

* Drip test TABLE XXV (CONTINUED) Gray Scale 7-Hour Kool-Aid Stain* Fastness to Xenon Light 20 AFU Color Change TABLE XXVI Description Original samples before quenching, hours Control test Post-treatments 5.0% Intratex N-1+4% ES* Composition 3 10% Composition3+4% ES Two-step IntratexN-1+ ES Intratex + ES * ES-Epsom salt Original samples before quenching hours ** Steam cleaned before quenching, hours sac by analysis %

* Error in application

Note: All post-treatments at pH 2, 160ºF (ºC).

**Drop test 0=best, 10 worst TABLE XXVII Stain Visibility* Stain Data with Benzoyl Peroxide

* 0 = invisible; 10 = bright TABLE XXVIII Grey scale rating Light fastness AFU Ozone fastness, cycles No. 2 fastness, cycle Colour change TABLE XXIX Dye bath %wt.Fas. Post-treatment wt.%/Fas. N/A Dip test**

* ES Ep-Epsom salt

** Forced Rating (K/A = Kool-Aid)

1 = best TABLE XXIX (CONTINUED) 7-Hour Kool-Aid Stain* Fastness to Xenon Light 20 AFU Color Change sac by Analysis %

* Drip test

Example 7 Process for using up ammonium thiocyanate on a dyed nylon fiber to improve its resistance to oxidizing agents Description of the embodiment

A dyed carpet fiber, especially one made of nylon, whether or not treated with a sulfonated aromatic condensate or other treatments, is susceptible to significant color fading due to exposure to ozone, benzoyl peroxide, and chlorine-containing products. The problem was alleviated to some extent when the dyeing industry switched to acid dyes from disperse dyes. Acid dyes were less likely to migrate and be destroyed by ozone because they were bound to the nylon by the electrons. However, the use of acid dyes did not eliminate these color fastness problems.

There are many antioxidants and antiozonants available on the market. These products are usually aromatic and contain amine or sulfur functionalities. These products have several disadvantages: aromatic substances usually turn the fiber yellowish upon further heat treatment, and the amine and sulfur functionalities cause a reduction in the lightfastness of nylon. Also, these chemicals are believed to act as perishable agents and it has been difficult to apply enough of them to the fiber to provide a long-term benefit.

The thiocyanates, such as ammonium thiocyanate, are antiozonants that are well known. The cation of the thiocyanate can be ammonium, sodium, potassium, zinc, copper, ferrous, ferric, methyl or phenyl. They have the additional advantage over the other antioxidants of not reducing lightfastness. However, it has not been economically possible to apply a sufficient amount of thiocyanate during dyeing to achieve long-term effectiveness, as it is also a perishable agent. (Ammonium thiocyanate also appears to agglomerate the dye molecules, which also increases ozonefastness).

In order to apply ammonium thiocyanate economically, it is necessary to demonstrate a process whereby it is consumed on the fiber in a substantial amount. At a pH of 7 and at 212ºF (ºC) (normal dyeing conditions), the ammonium thiocyanate will not be consumed on the fiber because it is water soluble and not very substantive to nylon. However, it has been found that at acidic pHs, especially at approximately pH 1.5 to 5, the ammonium thiocyanate is consumed on the nylon.

Comparison of different thiocyanates

A comparison was made of the performance of several organic and inorganic thiocyanate compounds applied to fluorocarbon treated cuff-knitted nylon carpet fiber that had been post-treated at a pH of 2, 140ºF (60ºC) and a liquid:good ratio of 20:1 for 20 minutes. No dyes were added. The following thiocyanates were evaluated. Added as received, % Thiocyanate activity, %

The amounts added introduced an equivalent amount of thiocyanate concentration into the fiber.

The ammonium, sodium and potassium thiocyanates were all equally superior to untreated nylon in terms of ozone and benzoyl peroxide resistance and chlorine bleach fastness. The other 15 thiocyanates were slightly more resistant to these color fading tests than the untreated nylon. The fastness to xenon light of all samples was similar to that of untreated nylon, with the exception of CuSCN, which was more stable, and the phenyl-based thiocyanate, which was much worse.

Effect of pH value

Using the same conditions as above but varying pH and using only NH4SCN, the percent consumption of NH4SCN on the fiber was measured at the pH values shown. pH value consumption, %

Effect of temperature

In another test under the same conditions and pH 2, the temperature was varied to achieve the following consumption values. Temperature consumption

Thus, it is expected that by increasing the temperature, more complete consumption can be achieved at higher pH values.

In a separate test, under the same conditions but with varying time, it was found that a time between 5 and 50 minutes had little effect on the depletion values. On the other hand, increasing the NH4SCN concentration lowers the depletion value. It was also found that applying increasing amounts of NH4SCN to the fiber above 2000 ppm had very little effect on the ozone fastness, a small effect above 1000 ppm, but a larger effect between 0 and 1000 ppm. It was noted that Delta-E changed from 6 at 500 ppm to only 2 at 1000 ppm for the standard 5-cycle AATCC ozone fastness.

DISCUSSION

The above examples represent only a few of many embodiments and variations of this invention. One skilled in the art would be able to select the proper conditions and amounts of chemical compounds for other embodiments of this invention to achieve the desired results after learning the teachings of this invention, including the examples and the broader teachings of the above Summary of the Invention. The broader teachings are based on the economic, technical and practical limits for practicing the invention. However, it may sometimes be desirable to operate outside these economic or practical limits for special reasons.

The following discussion will describe some of the practical, economic and/or technical limits of the parameters of the embodiments of this invention.

First, the following table lists the reasons for the given limits regarding the operating conditions of the continuous post-treatment process, including the two-step application processes, of this invention. Limit Change Reason Preheat water temp. below 140ºF (60ºC) and carpet temp. below 130ºF (54.4ºC) Preheat water temp. above 212ºF (100ºC) and carpet temp. above 210ºF (ºC) less than 75 wt. % per unit preheat step Extract to less than 30 wt. % per unit Extract to over 190 wt. % per unit Application pH below 1.5 Application pH over 5.5 Application of less than 200 wt. % per unit Application over 650 wt. % per unit sac conc. less than 0.25 g/L sac conc. over 40 g/L Application solution temp. below 140ºF (60ºC) and carpet temp. below 130ºF (54.4ºC) application solution temp. above 212ºF (100ºC) and carpet temp. above 210ºF (99ºC) less than 0.05 wt.%/fas. MgSO₄ more than 0.8 wt.%/fas. MgSO₄ less uniform application during subsequent treatment and less effective or economical for carpet heating atmospheric process, water cannot be heated above boiling point less uniform, poor penetration dilutes subsequent application fluid, less effective corrosive less effective due to compounds in aqueous solution penetrating too deeply into fiber, compositions do not use up less effective at high pH carpet fabric cannot hold much more aqueous solution uneconomical adverse color fastness results less than 0.03 wt.%/Fas. NH₄SCN more than 1 wt.%/Fas. NH4SCN less than 0.15 wt.%/Fas. sac more than 7.5 wt.%/Fas. sac more than 6 or 3 parts of the respective dispersants to the parts of sac less effective uneconomical uneconomical, possible adverse chemical activity

The following table lists the reasons for limiting the parameters for the two-step charge-charge process according to this invention. Limit Change Reason Second step: pH less than 1.5 Second step: pH more than 5.5 Second step temp below 110ºF (ºC) Long second step temp above 195ºF (ºC) First and second step liquid ratio: substance less than 10 First and second step liquid ratio: substance more than 100 First step temp below 158ºF (70ºC) First step temp above 212ºF (100ºC) Corrosive Less effective due to compounds in aqueous solution penetrating too deeply into the fiber, compositions cannot be used up at high pH Uneconomical, takes too long Less effective due to compounds in aqueous solution penetrating too deeply into the fiber Less uniform, poor wetting and penetration Uneconomical Uneconomical, uneven application, takes too long Atmospheric process, water cannot be heated above boiling point Limit change Reason Treatment time in first step less than 15 minutes Treatment time in first step over 90 minutes Treatment time in second step under 5 minutes Less than 0.05 wt.%/fas. fluorocarbon on pretreated fabric Over 0.4 wt.%/fas. fluorocarbon on pretreated fabric Under 0.25 wt.%/fas. MgSO4 Over 4 wt.%/fas. MgSO4 Under 0.03 wt.%/fas. NH4SCN Over 1 wt.%/fas. NH4SCN Under 0.15 wt.%/fas. sac Over 7.5 wt.%/fas. sac Spots and streaks, uneven Uneconomical Uneven application Does not provide soil-repellent effect Ineffective Low light fastness, uneconomical, poor dyeing, color changes Fabric discolors, fabric is stiff, poor color yield, yellowing

The advantages of the best mode for carrying out this invention using Composition 1 in a two-step continuous-continuous process as described above in Example 1 are set forth below. Most or some of the individual advantages set forth are also achieved by other embodiments of this invention.

- improved stain resistance, especially for carpet fabric with a high ICP nylon fibre,

- essentially eliminates the light-induced yellowing of a fibre treated with sulfonated aromatic condensate,

- reduces NO₂ yellowing of a fibre treated with sulphonated aromatic condensate,

- improves the colour resistance of a fibre treated with sulphonated aromatic condensate to fading by ozone and to oxidation by benzoyl peroxide,

- improves the penetration of sulfonated aromatic condensate and treatment chemicals into the carpet fabric, including the supporting surface or the carpet backing,

- does not significantly affect the dirt resistance of the fluorocarbon treatment on the fiber of the carpet fabric,

- improves the durability of the sulfonated aromatic condensate and treatment chemicals compared to steam cleaning with high pH detergents.

Claims (14)

1. A process for applying a water-soluble thiocyanate to a polyamide fiber when the fiber is brought into contact with the thiocyanate, characterized in that the contacting is carried out at a pH between 1 and 5. 2. Process according to claim 1, characterized in that the thiocyanate is ammonium, sodium, potassium or zinc thiocyanate. 3. Process according to claim 1 or 2, characterized in that the pH value is between 1 and 4. 4. Process according to one of claims 1 to 3, characterized in that between 0.1 and 12% of the fiber weight of thiocyanate is present during the contacting. 5. Process according to one of claims 1 to 4, characterized in that the thiocyanate is brought into contact with the fiber in a dye bath. 6. Process according to one of claims 1 to 4, characterized in that the thiocyanate is brought into contact with the fiber after dyeing the fiber. 7. A method according to any one of claims 1 to 5, characterized in that the fiber comprises a fluorocarbon for improving the soiling properties of the fiber and a sulfonated aromatic condensate is either present on the fiber or is applied together with the thiocyanate. 8. Process according to claim 7, characterized in that the fluorocarbon contains a perfluoroalkyl radical and the sulfonated aromatic condensate is formed by condensation of formaldehyde with one or more phenol(s). 9. Process according to claim 8, characterized in that the fluorocarbon is a mixture of oligomers formed by two reactions, namely firstly the reaction of pyromellitic acid dianhydride with a fluorinated alcohol, and secondly the reaction product is further reacted with epichlorohydrin, and that the condensate is formaldehyde condensed with an alkali salt of para-phenolsulfonic acid and with 4,4'-diphenolsulfone. 10. The method of claim 9, characterized in that between 0.1 and 12% thiocyanate, based on the weight of the fiber, and between 0.05 and 0.4% fluorocarbon, based on the weight of the fiber, are present during the contacting. 11. Process according to one of claims 1 to 4, characterized in that an aqueous sulfonated aromatic condensate is also used for contacting the polyamide fiber. 12. Process according to claim 11, characterized in that the proportion of sulfonated aromatic condensate used is between 0.25 and 0.40 grams of solids of the condensate per liter of the aqueous solution. 13. Process according to claim 11, characterized in that the sulfonated aromatic condensate is formed by condensation of formaldehyde with one or more dihydroxy-aromatic diphenol sulfone(s). 14. Process according to claim 11, characterized in that the condensate is formaldehyde-condensed with an alkali metal salt of para-phenolsulfonic acid and with 4,4'-diphenolsulfone.