POLYAMIDE STAIN RESIST PROCESS

Abstract: A process for improving stain resistance of nylon fibers by treatment with sulfonated aromatic-formaldehyde condensate and fluorinated dry soil resist agents.

Description: POLYAMIDE STAIN RESIST PROCESS BACKGROUND OF THE INVENTION This is a continuation-in-part of copending U.S. Serial No. 904,433 filed September 8, 1986. The invention relates to polyamide fibers treated so as to improve stain resistance. in particular, this invention relates to stain resistant polyamide fibers treated with sulfonated aromatic-formaldehyde condensation products and fluorinated dry soil release agents. DESCRIPTION OF THE PRIOR ART The prior art is replete with compositions and processes for improving the stain resistance of polyamide (nylon) fibers. The advantages of stain resistance is apparent for many of the uses of nylon, especially when used in carpets. U.S. Patents 3,663,157 and 3,519,669 disclose certain formaldehyde condensation products useful as stain resists. The use of fluorine containing agents to impart soil resistance to nylons is well known as illustrated by U.S. Patents 4,414,277t 4,209,610 4,195,105 and 4,192,754. U.S. patent 3,844,712 to Frickenhaus discloses a method of improving the wet fastness of polyamides dyed with cationic dyes by treatment with the salts of condensation products of formaldehyde and sulfonated diphenyl ethers. However, Frickenhaus does not disclose or recognize any improvement in stain resistance and especially, Frickenhaus does not recognize that his condensation products would increase the stain resistance of a polyamide fiber treated with a dry soil release agent. SUMMARY OF THE INVENTION In accordance with this invention there is provided a process for improving the stain resistance of polyamide fibers which comprises treating the fibers with a sulfonated aromatic-formaldehyde condensation product and a fluorinated dry soil release agent. Additionally, a process is provided for improving the stain resistance of such fibers by treatment with certain sulfonated aromatic-formaldehyde condensation products alone, i.e., sulfonated diphenyl ethers. Fibers treated in accordance with this invention exhibit excellent resistance to common anionic stain agents such as the food dye FD & Red Number 40, as found in Cherry Kool-Aid DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS The terms nylon and polyamide as used herein denote those synthetic long chain polyamides having recurring amide groups as an intregal part of the polymer chain. Exemplary of such polyamides are nylon 6, nylon 66, nylon 12, etc. The aromatic compounds that may be condensed with formaldehyde for use in the process of this invention are those which contain up to 30 or more carbon atoms and preferably have at least one phenol or naphthyl group. The aromatic groups may be unsubstituted or substituted with hydroxyl, alkyl groups of 1 to 18 carbon atoms and/or fluoroalkyl of 1 to 10 carbon atoms, including prefluoroalkyl groups. The aromatic compounds may be composed of two or more aromatic rings bridged by -O- -SO2-, -CnN2n-r -CO-, or a carbon to carbon bond. It will be understood that a necessary feature of the aromatic compound is its ability to condense with formaldehyde and to that extent a formaldehyde-reactive substitutent is necessary. Illustrative of the types of aromatic compounds that may be condensed with formaldehyde and used in the process of this invention are, benzenes, naphthalenes, xylenes, bis-phenols, phenols, naphthols, diphenyl ethers, diphenyl sulfones, diphenyl ketones, diphenyl alkanes, dinaphthyl ethers, dinaphthyl sulfones, dinaphthyl ketones, dinaphthyl sulfones, and the like. As indicated above1 the aromatic compounds may be unsubstituted or substituted with hydroxyl, alkyl and/or perfluoroalkyl groups. Preferably, the aromatic compound is first sulfonated and thereafter condensed with formaldehyde although the unsulfonated compounds may be first condensed with formaldehyde and the condensate then sulfonated. Sulfonation is preferably accomplished by direct addition of chlorosulfonic acid. Alternatively, S03 or sulfuric acid may be used although higher temperatures are required with the acid. Prior to reaction with formaldehyde, the sulfonated aromatic compound is diluted with water. An aqueous solution of formaldehyde is added with the mole ratio of sulfonated aromatic compound: formaldehyde being in the range of 1.0 to 2.0, preferably 1.5 to 1.7. More preferably, the sulfonated aromaticformaldehyde condensation products are compounds having the following structure (hereinafter called the "preferred DPE condensate"): EMI3.1 wherein m is O to 4, n is 0 to 3 and x is 1 to 5. Most preferred are the compounds wherein m is 0 or 1, n is 0 to 2 and x is 1 to 3, except the nonpreferred species are compounds wherein m + n = 0 or 1 along with x > m + n + 1, or wherein m = o, n = 1 and x = 2. A particularly wellperforming compound is when m = 1, n = 0 and x = 2. Although the use of fluorinated dry soil release (DSR) agents have been previously employed to impart stain resistance to polyamide carpet fibers, it has been found, in accordance with this invention, that the use of such DSR agent in conjunction with the sulfonated aromatic condensate results in a synergistic effect producing a superior stain resistance than either treatment agent alone. Additionally, the resistance of such fibers to ozone fading is surprisingly improved. The term fluorinated dry soil release agent as used herein is intended to denote those agents known and used in the art to impart increased soil resistance to polyamide fibers, particularly, carpet fibers. Particularly useful in the process of this invention are the fluorinated dry soil release agents of the types disclosed in U.S. Patent Nos. 4,191,754; 4,604,316 and 4,605,587, which are incorporated herein by reference. It is preferred that the fiber first be treated with the fluorinated dry soil release agent and thereafter with the sulfonated aromatic-formaldehyde condensate although that sequence may be reversed. The compounds used in the process of this invention impart excellent stain resistant properties when applied to polyamide surfaces. While not wanting to be bound by any theory, it is believed that under the special application condi tions, the sul fonated aromatic -formaldehyde condensate products saturate the nylon near the surface of the fiber. This results in a high negative charge density which forms an ionic barrier and thereby inhibits the sorption of water soluble food dyes such as are found in artificially colored foods. The sulfonated aromatic-formaldehyde condensates useful in accordance with this invention are water soluble and can be applied to nylon in a variety of ways. Typically, the compounds are applied to dyed fiber from either a dilute or concentrated aqueous solution with a concentration range between 0.001 and 75 weight percent. The solution is contacted with the polyamide fiber for 5 seconds to 45 minutes at temperatures ranging from room temperature to about 1000C. The pH of this solution should be between 1.0 and 5.0, preferably about 2.0. It has been found that when the pH of the solution is at the lower pH values the percent exhaust and stain resist property of the treated fiber is significantly improved. For this reason, it is prefered to employ sulfonated aromatic condensates with -SO3H groups instead of sulfonate salts. After treatment the fiber is water extracted and oven dried at 1200C. The sulfonated condensates useful in this invention can be applied to dry or wet fiber either as a concentrated or dilute solution. The treated fibers should contain the sulfonated condensate in amounts of between 0.05 and 10 OWF (on the weight of fibers) and the treatment bath conditions should be maintained accordingly. The method for applying the fluorinated dry soil release agent (DSR) to polyamide fibers is known in the art and is thus not necessary to describe in detail. In general, the fibers may be contacted with a spin finish containing the DSR agent in a known manner or other suitable procedures may be employed. The amount of DSR on the fibers resulting from the process of this invention should be between 0.1 and 1.0% on weight of fabric (OWF). The treated nylon carpet fibers are tested for stain resistance in the following manner: A treated sample of nylon carpet yarn in circular knit sleeve form is placed on a non-absorbent surface and a small (10 ml) beaker containing 2 ml of staining solution, e.g., Cherry Kool-Aid is inverted on the fabric and slowly agitated in such a manner that the liquid is-retained within the beaker and in contact with the fabric until the termination of the test, or absorption of the staining solution by the fabric takes place. After 5 minutes, or other suitable period of time, the beaker and remaining solution are removed and any excess liquid on the fabric is blotted away with absorbent paper towels. The depth of the stained area is then visually assessed by use of the AATCC Gray Scale for staining, the AATCC Chromatic Transference Scale, or other suitable comparative method. It has also been found, in accordance with this invention that certain sulfonated aromatic-formaldehyde condensates, namely those produced by reacting formaldehyde with sulfonated diphenyl ethers (DPE), can by themselves impart stain resistance to polyamide fibers. The DPE may be unsubstituted or substituted with 1-18 carbon alkyl or 1-10 carbon fluoroalkyl. These diphenyl ether condensation products are produced, as described above, by sulfonating DPE or its alkyl or fluoroalkyl derivitives and thereafter condensing with formaldehyde. Unsubstituted DPE is prefered but, prior to sulfonation the DPE may be alkylated or fluoralkylated. However, the alkylation process, generally conducted by a Friedel-Crafts type reaction, adds cost. Preferably the sulfonate is -SO 3H as this results in a lower pH of the treatment solution. In addition, the treatment of polyamide fibers with the DPE condensate in conjunction with the above described DSR results in fiber characteristics surpassing those obtained by either agent alone. Example 1 A diphenyl ether - formaldehyde condensation product is produced as follows: to a reactor containing 170 grams of DPE is added 128 grams of chlorine sulfonic acid over a 1 hour period at 50 - 600C. After air sweeping to remove HC1 there is added 65 grams of water and thereafter, while maintaining the temperature at 50 - 60-C there is added 49 grams of a 37% (by weight) aqueous formaldehyde solution over a 30-minute period. The liquid is then digested for 10 hours at 100 - 105.C. The product 265 grams in 107 grams of water is drained from the reactor. A mixture of the "preferred DPE condensate compounds previously described was formed. A 7.5 gram dry nylon 6 sleeve is contacted with 0.15 grams of the condensation product so produced and 175 ml of water for 30 minutes at 71it. The nylon 6 sleeve had been previously treated with a fluorinated dry soil release compound as described in Example 1 of U.S. Patent 4,192,754 and mock dyed. The nylon sleeve is then squeezed and paper towel dried before placing in an oven at 1200C for 30 minutes. A 5-minute stain test with a Cherry Kool-Aidw solution gave a 5 rating on the Chromatic Transference Scale (5 = best, 1 = worst) compared to an untreated sleeve control rating of 1. Example 2 A 7.5 gram nylon 6 sleeve which had not been pretreated with a fluorinated dry soil release agent but which had been mock dyed was contacted with 0.15 grams of the condensation product produced in accordance with Example 1 in 175 ml of water for 30 minutes at 710C. The nylon sleeve is then squeezed and paper towel dried before placing in an oven at 1200C for 30 minutes. A 5-minute stain test with Cherry Kool-Aidw solution gave a 3+ rating compared to a 1+ rating for the untreated sleeve control. Example 3 A diphenyl ether-formaldehyde condensation product is produced as follows: to a reactor containing 170 grams DPE in 500 ml of carbon disulfide there is added 30 grams A1CL3. 334 grams of hexafluoroacetone is introduced over a three-hour period while the temperature is held at 0 10it. After dilution with ice water1 phase separation and removal of CS2, the product, a fluid liquid at 25it, is treated with 128 grams of chlorosulfonic acid added over a one-hour period of 30 - 50.C. There is then added 80 grams H2O. Aliquots are taken from the reactor and a 37 weight percent formaldehyde aqueous solution is added such that the mole ratio of sulfonated DPE to formaldehyde ranges from 1-.3 to 1.8. A 7.5 gram nylon 6 sleeve which had been previously treated with a fluorinated dry soil release agent as described in Example 1 of U.S. Patent 4,192,754 is contacted wth 0.35 grams of the condensation product so produced in 175 of water for 30 minutes at 710C. The nylon 6 sleeve had been previously mock dyed. A 5-minute stain test with Cherry Kool-Aid" solution gave a 5 rating. Example 4 A nylon 6 sleeve which had not been pretreated with a fluorinated dry soil release agent but which had been mock dyed was contacted with 0.15 grams of the condensation product produced in accordance with Example 3 in 175 ml of water for thirty minutes at 710C. The nylon sleeve is squeezed and paper towel dried before placing in an oven at 120'C for 30 minutes. A five-minute stain test with Cherry Kool-Aid' solution gave a 4 rating. Example 5 A dihydroxy diphenyl sulfone formaldehyde condensate is sold under the trade name MESITOL PS by Mobay Chemical Company. Four nylon 6 sleeves composed of fibers previously treated with the DSR described in Example 1 of U.S. Patent 4,192,754, and four nylon 6 sleeves containing no DSR, are contacted with a solution of the sulfonated aromatic condensate under conditions adjusted to result in treated sleeves containing 0.2%, 0.5%, 1.0% and 2.0%, OWF of the condensate. Stain testing of the resulting samples, along with two control samples, as described in Example 1, gave the following results: % Onff No DSR DSR Treated 0 1 2 0.2 1 3 0.5 2 4 1.0 2.5 5 2.0 3.5 5 An additional feature of the present invention lies in a process for treating polyamide fibers with the sulfonated aromatic-formaldehyde condensates described above in conjunction with treatment of the fibers with 0.1 to 5.0% (OWF) of the 2-(2-hydroxyaryl)-2H-benzotriazoles described in copending application Serial No. 889,705 filed July 28, 1986, which is incorporated herein by reference. Surprisingly, the treatment with these benzotriazoles does not adversely affect the stain resistance characteristics obtained with the sulfonated aromatic-formaldehyde condensate while the lightfastness of the treated fibers exhibits significant improvement. Example 6 As described in copending application Serial No. 889,705 nylon 6 sleeves predyed silver were treated with aqueous baths containing a condensate of formaldehyde and unsubstituted diphenyl ether prepared as described in Example 1 above, and the compounds described in Example 1 (Example 6a) and Example 2 (Example 6B) of said copending application. The bath temperature was 110OF (380C) and pH 2.1. Similarly a control was prepared from a bath containing only the sulfonated DPE-formaldehyde condensate of Example 1 (Example 6c). Bath conditions and treatment time were such that the treated nylon contained 2.0% OWE of the DPE-formaldehyde concentrate and 0.5% OWF of the benzotriazole. After treatment stains were created on the sleeves with Cherry Kool-Aidw containing FD & C Red 40 by forcing about 5 cc of the Kool-Aid' into the fabric of the sleeve and blotting after 5 minutes. Results are given below. Stain rating is on an 0 to 10 scale used by trained observers, unaware of which sample was treated with which agent(s). In this scale 0 is best and 10 is worst. The lightfastness was measured by AATCC 16E. Lightfastness b E Gray Scale* Stain Rating 120 AFU 120 AFU 6a 0.75 2.52 3.67 6b 0.75 1.70 3.67 6c 0.75 3.49 3.17 * Average Improved lightfastness, i.e., less fading, is reflected by higher Gray Scale average and lower a E. Example 7 The effect of the process of this invention on the ozone fading of polyamides is illustrated as follows: samples of nylon 6 carpet, which had been treated with 2% OWF of a diphenyl ether-formaldehyde condensation product in the manner described in Example 1 except that the treatment bath temperatures were set at 1100F (380C), 120OF (49-C), and 140OF (60etc) were teated for ozone fading by AATCC Method 129 (2 cycles) with the following results: Bath Temperature llO'F 120 F 1400F (380C) (49 C) (60 C) Control*, Gray Scale Reading 1 - 2 2 2 Example 7, Gray Scale Reading 3 2 - 3 3 * The control sample was treated only with DSR.

Claims: WHAT IS CLAIMED: 1. A process for improving the stain resistance of polyamide fibers which comprises treating the fibers with a sulfonated aromatic-formaldehyde condensate and a fluorinated dry soil release agent. 2. A process according to claim 1 wherein the treated fiber contains between 0.05 and 10%, based on the weight of the fiber, of the sulfonated aromaticformaldehyde condensate, and said sulfonated aromatic compound contains at least two aromatic rings connected by -O-, -SO2¯, ¯CnH2n-, -CO- or a carbon to a carbon double bond. 3. A process according to claim 2 wherein the sulfonated aromatic compound is a diphenyl ether. 4. A process for improving the stain resistance of polyamide fibers which comprises treating the fibers with the sulfonated condensation product of a diphenyl ether and formaldehyde. 5. A process according to claim 4 wherein the fibers are also treated with a fluorinated dry soil release agent. 6. A process according to claim 4 wherein the diphenyl ether contains fluoroalkyl substituents. 7. A process for improving the stain resistance and lightfastness of polyamide fibers which comprises treating the fibers with a sulfonated aromatic-formaldehyde condensation product and a sulfonated 2-(2'-hydroxyaryl)-2H beniotriazole. 8. A process according to claim 7 wherein the treated fiber contains between 0.05 and 10%, based on the weight of the fiber, of the sulfonated aromaticformaldehyde condensate. 9. Th. process of claim 2 wherein the condensate is a compound or mixture of compounds selected from the compounds having the following structure: EMI13.1 wherein m is O to 4, n is 0 to 3 and x is 1 to 5. 10. The process of claim 8 wherein the condensate is a compound or mixture of compounds selected from the compounds having the following structure: EMI13.2

Inventors: BERENBAUM MORRIS BENJAMIN, BONFIELD JOHN HENRY, COLE CHARLES JAYROE, HARRIS PAUL WESLEY, IZOD THOMAS PAUL, ULMER HARRY EDWARDS, BERENBAUM, MORRIS, BENJAMIN, BONFIELD, JOHN, HENRY, COLE, CHARLES, JAYROE, HARRIS, PAUL, WESLEY, IZOD, THOMAS, PAUL, ULMER, HARRY, EDWARDS
Applicants: ALLIED CORP, ALLIED CORPORATION
Application year: 1987
Main classification: D06M15
IPC codes: D06M15