CA2122209A1 - Nylon fibers with improved dye washfastness and heat stability - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed is a polyamide fiber having improved dye washfastness and heat stability which consists of a fiber forming polyamide with an additive such as water, an alcohol, an amine and a heat stabilizer such as a phenolic compound ora phosphite containing aryl groups or a mixture thereof.

Description

21222~9 . .
~ IN-1470 .i ~ NYLON FIBERS WITH IMPROYED DYE WASHFASTNESS AND HEAT STABILITY

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Field of the Invention ~t The present invention is directed to nylon fibers with improved dye washfastness and heat stability in particular it is directed to nylon fibers containing an addlt~ve such as water9 an alcohol, or an amine and a heat stabilizer such as a phenolic compound or a phoshite containing aryl groups or mixtures thereof.
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~=~ BACK6ROUND OF THE INVENTION

Anionic ac~d dyeing of polyamide yarns involves the reaction o~ the amino end group of the nylon yarn with the sulfonic acid end group of the dye molecules.
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Depending on their chemical structure; the anionic dyes could possess a mono-, or a di-, or a tri-sulfon~c acid end group. The reactivity of the dye with the f~ber ~s d~rectly proportional to the number of funct~onal groups present 1n thedye and/or the fiber. Therefore, it follows that the greater the number of dye molecules that bond with the amine endgroups of ~he fiber, the better the washfastness of the fiber.
~' Several appl1catlons ~nvolve treatment of heat to the fabric pr~or to dyei~g.
A typical example is the case of elastic fabrics which are knitted with elastomeric yarns, e.g. Lycra~ (DuPont, Wilmington) which imparts the stretch tothe fabrlc. Heatsetting of the fabric prior to dyeing is essential to avoid curling of the fabric. Typ~cal heat setting temperatures range between as low as 90C to very severe temperatures of 200C. When heat setting is conducted at elevated temperatures such as abovel40C, in air, oxidatiYe degradation of the am~no- endgroups occurs destroying the functional groups present in the fiber.
This depletion of amino end groups reduces the affinity of the dye molecules to the fiber. Such a fabric picks up less dye than a non-heatset fabric, has a worse ~' ~ wash fastness and has a dull appearance. In more severe cases the preheatset-and-~, .,~, v. ~ . .,- ~ ~, ;. - . - . -:``
` ` `~` 2:~ ~ 2`2 ~ 9 dyed fabrics also exhibit streaky appearance. Therefore, there exists a need toimprove the resistance to thermal degradation of polyamide yarns so as to retain~; the brightness of the fabric, improve the washfastness of the fabric and improve the uniformity of the dyed fabric.
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:, - To increase dye pick up of a heat set fabric, dyeing methods are modified. This lnvolves 1ncreasing the temperature of the dye bath in some cases and/or reducing the pH sf the dye bath, in many cases. Although, the modified dyeing procedure increases the affinity of the dye into the fiber, it is a temporary phenomenon, since after dyeing, the fabric is washed thoroughly to remove thc acidity in thePabricO The dye molecules that are thus entrapped in the fiber, are loosely bound due to lack of chemically reactive sites in the fiber. Such molecules are susceptible to diffuse out of the fabric during subsequent washings-. The physical size of these entrapped dye molecules have a significant influence on the diffusion of the dye out of the fiber and hence, also the dye wash fastness of the fabric. Thus fabrics dyed with smaller'dye molecules would exhibit worse ~! washfastn~ss than larger ones. In many cases, the smaller dye molecules are also those wh~ch possess a ~ono-sulfonic acid group, i.e. the least number sf ~l functional grcups, and hence a lesser affinity to the fiber. Pre-heat set ii polyamide yarns dyed with such dyes exhibit the worst washfastness.
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To alleviate this problem, several methods have been invented. Most of these techniques lnvolve a chemical treatment after the dyeing process. DE-A 4,131,926describes a process wherein the dyed substrates like nylon are treated with ~7~ dlspers~ons of sterically hindered cycloaliphatic amines, which improves light and washfastness.

DE-A 3,330,120 discloses an aftertreatment of polytmide textiles, dyed with anion~c dyes, with a polybasic compound which was a reaction product of a polymine with a cyanamide derivative to improve the wetfastness and washfastness.

Yet another method is disclosed in JP 81 53, 293 wherein acid dyed polyamide , fibers are treated with a color fixing agent. This color fixing agent is based on a condensation praduct of a polysulfone, a compound containing amino groups and sulfonic acid groups, and an aldehyde. The washfastness of polyamide fibers ~'J, 2 ,,, :

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; treated with this agent is improved.

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; Similarly, JP 80 71,884 describes a polymeric quaternary ammonium compound which when applied to the face of a printed polyamide fabric, improves- the colorfastness of the fabr;c.
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Although improvements are claimed in wash~astness by chemical aftertreatment processes, cons~derable deficlencies still exist in several appltcations. Theserelate to the fundamental ~ssue of reduced aff;nity of certain dyes w;th the fiber due to the depletion of amino end groups during preprocessing of the polyamide fabric. A more important ~ssue is that of increased cost of processing the fabric. The chemical aftertreatment not only involves the sost` of an ~;
additional processing step but also the cost of chemical waste disposal and effluent water treatment. With tighter env;ronment protection regulations on thetypes oF disposable effluents, the economics of aftertreatments could get to be restr~ctive.

Therefore, there exists a need for polyamide fibers that would possess better washfastness of polyamide yarns w;thout ~ncreasing or alter~ng the chemicals that are used currently ~n the dy2bath. Furthermore, there also exists a need to achieve a better exhaust~on of the dyebath so as to reduce the dyes and chemicals~ -belng released as effluents ~n the waste water. ~ ~
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U.S. Pat. No. 4,863,664 discloses a high speed process of making polyamide f~laments by melt mixing polyamide with some additives like water, alcohols or organ~c acids prior to splnning. Although, the process claims to improve yarn qual~ty, processabillty and dye washfastness of the fabric, it does not address ~5 the issue of heat stab1lity of the f;bers made from such a process. The poor I heat stabil;ty and the resulting streaky dyeing are s;gn;f~cant disadvantages of this process.
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It was the object of the present invention to reduce or eliminate thedeficiencies existing in current polyamide fibers in relation to washfastness and heat stability of the fabric and prov;de polyamide fibers, with improved dye `i`-```~` 2122.~9 . . . ~
~ washfastness and heat stability.
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's ' r~! . i ~! Still another object was to provide polyamide fibers for the manufacture of yarns .';4'.1 which would possess red~ced yellowing and retain the whiteness of the fabric after heat treatment , ;t.j Another ob~ect was to provide polyamide fibers for the production of dyed fabrics ii~ hav~ng ~mproved uniform~ty after heatsetting.
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Another ob~ect was to provide polyamide fibers which achieve a greater exhaustion of the dye bath at an increased rate thereby reducing the release of e~fluents of waste dyes and chemicals in waste water.
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Yet another object was to provide polyamide fibers for the production of dyed fabrtcs hav1ng deeper dye shades.

~t S~nce swi~wear ~s one of the potent~al applications for the yarns of the present inventlon where resistanc~ to fading in a chlorinated water pool is a ~ajor requlrQment9 1t was another ob~ect of the present invention to prov1de polyamlde~ fibers which would possess improved resistance to color fading in a chlorinated r3 water pool.

3 summarY of the InYention The objects of the present invention were achieved with a polyamide fiber, whichcomprlses:
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~ (a) a fiber forming polyamide;
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(b) an additive selected from the group consisting of water, alcohols, amines and mixtures thereof; and -~q ~ 4 -.

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j, (c) a heat stabilizer selected from the group consisting of phenolic compounds, phosphite containing aryl groups and mixtures thereof.
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~ Detailed Description of the Preferred Embodiments ,; ' Fiber forming polyam1des (a) are well known by the generic term "nylon" and are long cha1n synthet~e polymers containing amide (-CO-NH-) linkages along the mainpolymer chain. Suitable fiber-forming or melt spinnable polyamides of interes~
for this ~n~entlon include those which are obtained by the polymeri ation of a lactam or an amino acid, or those polymers formed by the condensati~n o~ a diamine and a dicarboxylic acid. Typical polyamides include nylon 6, nylon 6/6,nylon 6/9, nylon 6/10, nylon 6/12, nylon 6T, nylon 11, nylon l2 and copo1ymers therof or mixtures thereof. Polyamides can also be copolymers of nylon 6 or nylon 6/6 and a nylon salt obtained by reacting a dicarboxylic acid component such as terephthalic acld, isophthalic acid, adipic acid or sebac~c acld with a diam~ne such as hexamethylene diamine, metha-xylene diamine, or l, 4-bisaminomethyl cyclohexane. Preferred are poly- eps~lon-caprolactam (nylon 6 and pslyhexamethylene adipic acid or sebacic acid with a dia~ne such as hexamethylene diam~ne, metha-xylene diamine, or 1,4-bisaminomethyl cyclohexane.
Preferred are poly- epsilon- caprolactam (nylon 6) and polyh~xamethylene adipamide (nylon 6/6). Most preferred is nylon 6.
, ., Sultable addit~ves (b~ are water, mono-and polyalcohols, mono and diamines and mixtures thereof. Suitable monoalkahols are Cz - to C18 - alkohols like ethanol, propanol, butanol, hexanol, decanol, undecanol, octadecanol; arylsubsitutedalcohols like benzyl alcohol and benzoin.
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Suitable polyalcohols are glycols like ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, neopentylglycol ~ glycerin, trimethylolethan, trimethylolpropan and pentaerythritol.
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Suitable amines for the additive (b) are mono- and d;amines, preferred are 21?.2209 diamlnes like hexamethylene d~amine, meta-xylene diamine and 1,4 bis-aminomethylcylohexane.

The preferred additi~e (b) is triethylene glycol and hexamethylenediamine.
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The additive (b) is used in an amount of ~rom about 0.5 to about 5% by weight, ~ -preferably ~rom about 1 to about 4X by weight, most preferred from about 1.5 to about 3% by weight, based on the total amount of the polyamide fiber.
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I,~j Suitable heat stabili~ers (c) are phenol~c compounds, phosph~tes containing arylgroups and m1xtures thereof.

Suitable phenolic compounds are compounds which contain at least one p~enolic group with two lower alkyl substitutents in the aromatic ring, at least one of which is in ortho position of the hydroxyl group. The lower alkyl groups are preferably branched groups such as t-butyl. Examples for alkyl substituted phenolic groups are 3 t-butyl-6-methyl-~-hydroxy phenyl and 3,5-d~methyl-4-hydroxyphenyl.

Examples for phenolic compounds are disclosed ln U.S. Pat. No. 4,187,2129 the d~sclosure thereof is herewith ~ncorporated by reference. Preferred are phenoliccompounds such as 2,2'-methylene-b~s(6-tert.-butyl-4-methylphenol), 2,2'-methylene-b~s(6-tert.-butyl-4 -ethylphenol~, 2,2-bis(3,5-di-tert.butyl-4-~ hydro~yphenyl~-propane, '~i1 1,3,5-trls-(3,5-di-tert.-butyl-4-hydrsxphenyl-propionyl)-hexahydro-s-tr~a~ine, ;~ N,N'-d1(3,5-d;-tert.-butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine, 1,3,5-tri(3,5-dl-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, pentaerythritol-tetra-[3-(3,5-di-tert.-butyl-4-hydroxy-phenyl)-propionate], B-(3,5-di-tert.-butyl-4-hydroxyphenyl)-propionic acid-n-octadecyl ester, thiodiethylene glycol- ~ ~4-hydroxy-3,5-di-tert.-butyl-phenyl]propionate, 2,6-di-tert.-butyl-4-methyl-phenol, and 3.9-bis[l,l-dimethyl-2-(3,5-ditert.-butyl-4-hydroxy-phenyl)-ethyl~-2,4~8,10-tetraoxaspiro-[5,5]-undecane.
~ -., U.S. Pat. Nos. 3,584,047 and 3,677,965 disclose polyamides containing these alkyl ~: 2~222~9 -"
substituted phenolic groups, more specifically polyamides derived from alkylhydroxyphenylalkanoic acids and polyamines. These compounds are ~, particularly su~table for the present invention and the disclosures of these patents are herewith incorporated by reference.

Suitable phosphites containing aryl groups are disclosed for example in U.S. PatNo. 4,187,212, the disclosure thereof is herewith incorporated by reference.
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Pref~rred phosphites are:
tr~s-(2,5-d~tert.-butylphenyl)-phosphite, tris-~2-tert.-butylphenyl)-phosphite, tris-(2-phenylphenyl)-phosphite, tr1s-(2-(1,1-dimethylpropyl~-phenyl]-phosphite~
tris-[2,4-di-(1,1-dimethylpropyl)-phenyl]-phosphite, tris-(2-cyclohexylphenyl~-phoshite, and tris-(2,4-ditert.-butylphenyl~-phosphite.

Particularly useful are mixtures of phenolic compounds with phosphites.
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The heat stabillzer (c) is used in an amount of from about 0.025 to about 2X by weight, preferably from about 0.1 to about 1.5 by weight, most preferred from about 0.15 to about 1.25X by weight, based on the total weight of the polyamide flber.
~ . -There are many methods and processes for the production of the polyamide fibersof the present invention. In one process the heat stabilizers (c) may be added before or during the polymerization of the polyamide and the additive (b) may beadded before or during processing of the polyamide into a fiber.
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In another process, both the heat stabilizers (c) and the additives (b~ may be added simultaneously or separately before or during polymerization of the polyamide and the mixt~re may be processed into a fiber in the next step.
Alternat~vely, the heat stabilizers ~c) and additives (b~ may be mixed together homogeneously and added to the polyamide during its processing in the form of fibers. The addition of the heat stabilizers (c) and additi~es (b) to the :

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polyamide during processing of the fibers could be performed in several ways.
In one case, the components (b) and (c) may be volumetrically or gravimetricallyfed individully or as a mixture to the extruder using a suitable feeding system eg. Colotronics~ system (Colotronics Inc.) or K-tron~ gravimetric feeder (K-tron, Switzerland). ln another case, the components (b) and ~c) may be mixed homogeneously in a suitable non-react~ve inert liquid and the mixture may be injected in the extruder to achieve a melt mixing with the polyamide.
Alternatively, if one or both of the components are in a liquid ~orm, the mixture could be injected directly into the extruder without dispersing it into the inert liquid. In another method the mixture of the two components (b) and (c) may be ~elted and the melt may be injected into the extruder using a liquid inject~on system.

Additionally, another method to process the polyamide fibers of the present invention would be by preparing a concentrated master-batch of polyamide chips containing high levels of one or both compohents (b) and (c) and mixing tha$
master-batch with the polyamide polymer to achieve the desired levels of the components in the fiber. The mixing of the two polymers, namely, the master-batch chips and the polyamide chips could be done using a volumetric or a gravimetr~c feeding system at the opening of the extruder or could be done us~nga side-arm on the main extruder wherein the molten streams of the two polymers may be m1xed. The homogeniety in the two streams could be achieved using ~n-line static mixers.

The methods described herein may be used as depicted or may be used as a combination with two or more processes. Further processing of this mixture may be performed as follows:

The melt mixing may be performed in an extruder at a temperature of 20~ to 400C
above the melting temperature sf the polyamide being used.
The additive (b) and the heat stabilizer (c3 may be added together or separatelyto the polymer chips or grannules before they enter the extruder, or may be added into the opening of the extruder together with the polyam;de or may be added through a side extruder directly into the melt, where the mixing to a homogeneous mixture takes place.

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., 21222~9 ; l' The homogeneous mixture of fiber forming polyamide (aJ, additive (b) and heat stabil~rzer (c) may be spun through a conventional spinnerette to form fibers, which are solidified by quenching them with air. The fibers may be treated witha finish such as a lubricating oil or a mixture of oils and an antistatic agent.The applicatlon of finish prov;des an efflcient runnability of the fiber on the spinn1rng machine and in subsequent processing steps. The fibers may be spun inany one of the follo~ing ways:

1) a two step process at a speed from about 400 m/min to about 1500 m/min, preferably from about 600 m/,mrin to about 1200 m/min and drawn in a second stepor, 2~ a one step spin-draw-wind process or 3~ a one step high speed spinning process without drawing the yarn, at a speed of at least about 3000 m/min, preferably with at least about 3500 m/min.

An optional step is texturi~ing the fibers with, for example, and air jet, gear cr~rmp~rng, stuffer box, or edge crimping process. In several cases, drawing and texturi,~frng could also be performed ln a single step, such as in case of a onestep bulked contlnuous filament (BCF) yarn process for carpet enduse. The textured yarn produced on such a process is taken up to be wound on a package.

The fibers of the present invention have deniers (den;er = weight in grams of a slngle filament with a length of 9000 meters) in the range of about 0.5 to 20.0 denier/f~rlament ~dpf). A preferred range is from about 0.7, to 3.0 dpf. :. '?

The fl,bers of thie present invention have an am~rne end group (AE6) content of from about 15 to about 70 me~kg, preferably from about 35 to about 50 me~/kg, and a relative viscosity (RV) of from about 2.2 to about 3.2, preferably from about 2.0 to 3Ø

The combined effect of the heat stabilizer (c3 and the increased AEG of the polymer resulting from the additive (b), results in an enhanced dyeability, improved wash fastness~ bétter heat stability. An addit;onal advantage also ? ~ .
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results from the reduction in the starting concentration of dye bath to achieve shades similar to that of a control yarn. Alternatively, deeper shades which cannot be achieved with a control yarn are possible with this 1nvention.
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.!i, " Other advantages become apparent from the following examples.
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Examples:
Nylon 6 (Ultramid~v 8S 700F, BASF Corporation, Freeport, TX) was extruded at a temperature of 272C through a 12 hole round cross section spinneret of hole diameter 200 microns and capillary length of 400 microns. Triethylene glycol (TE6) was injected at the throat of the extruder during spinning by means of a Zenlth metering pump at different levels. The filaments were cooled 1n a quenchcabinet where air at 55- F and 65% relative humidity was blown at 100 ft/min.
The filaments passed through a tangling jet and were taken up by a set of godetsrunning at 5500 m/min. The yarn then went through a steam chamber where steam at a temperature of 130-C was mainta~ned at a pressure of 65 psi. The yarn was wound on a Barmag S~-6 winder at a speed of 5390 m/min~

Table I lndicates the relative viscosity, ~he am~ne end group content (AEG) and the ~echanical properties of the yarn obtained using different levels of triethylene glycol (TEG) addition.
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TABLE I
Exam. X TEG R e 1 . A E G Denier T e n Elo (%) % BWS
Visc.(meq/kg) (gpd) Y~
0 2 . 7g 34 . 6 ~2 . 1 3 . 82 53 . 5 ~ . 53 2 1 2.5~ 39.5 42.1 ~.11 52.2 7.87 i~ 3 I.S 2.~3 41.9 4~.1 4.07 51.8 7.53 4 2 2.47 44.5 42 4.02 50.6 8.17 ~1 5 2.5 2.4 47.1 41.8 3.91 49.7 B.33 6 3 2.36 49.7 41.97 3.83 49.9 8.20 TABLE Il , Example Density ~g/cc) % Alpha % Gamma % Crystallinity ~:
.13672 52.0 48.0 30.5 21.13843 46.8 53.? ~2.2 31.13951 38.8 61.2 -~3.6 41.139û4 40.7 59.3 33.0 51.14134 39.9 60.1 35.0 51.13961 41.6 58.4 33.5 The morphologlcal properties of the F~bers are listed in Table II. The density of fibers was measured using a Quantachrome Helium pycncmetry. No correct~on wa~ made for additive volumes. A typical high speed spun polyamide fiber exhib~ts two types of crystal structures, namely, alpha and gamma. The percent composition of each of the crystal types present can be obtained using Wide Angle X-ray Diffraction (WAXD) techniques. A theta-two ~heta equatorial WAXD
scan of nylon 6 can be resolved into 5 peaks, 4 of which are assigned as crystalline peaks, namely, ~200. rO01- Y200 and ~002. The relative fractions of alpha and gamma crystals can be obtained from ratios of the integrated intensities of the resolved peaks. Equatorial ~-2~ difractometer scans were :~ :

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obtained on a Siemens DS00 x-ray generator with a Cu-K~ radiation generated at 40 kV and 25 mA. The five-line model developed by Heuvel and Huismann (H. M.
:.``! Heuvel and R. Huismann, J~ App7. Po7ym. Sci., Po7ym. Phys. Ed., 19, 121 (1981)) was used to resolve peaks and obtain the ~/y ratios.
The crystallinity was calculated based on the fiber densities obtained from ~ the He-pycnom~ter and the ~-r crystal ratios, using the formula:
li %Xc= P ia 10 ~ ,. Pc P~
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where Xc is the volume fraction crystall~nity, p is the density of Fiber, p~ ~s the density of a~orphous phase (1.I0 gm/cc3 and, pc ~s the density of the pure crystalline phase, which is obtained from the following equation, p _~1.23*% a) (1.21~%y) ...

Density of pure alpha phase is taken as 1.23 gm/Cm3 and that of pure gamma phase~s assumed to be 1.21 gm/cm~. aPolymer Handbook,~ Ed. J. Brandup and E. H.
Immergut, Publ. J. Wiley and Sons, N.Y. (1989)~
Mechanical properties oF the fiber were measured using the Statlmat tensile tester at a rate. nf extens~on of 24 cm/min and a gage length of 20 cm.

To determine the boiling water shrinkage, 7engths of skeins (7~ of 90 m of yarn were measured at a pretens~on of 0.056 gm/den and were allowed to shrink freelyin a boiling water bath for 1 min. The length of skeins (7) were remeasured at the same pretension and the percent shrinka~e was calculated based on d7/70, where dl is the change in length of the sample, (~O - 7).
Relative viscos~ty of yarns were measured by a single point method. Flow times of solutions (t8) of 1X by weight yarns in formic acid were measured using a Ubelhode viscometer and were compared to those of pure solvent ~to~. The relative viscosity (RY~ was calculated as tJto. The RVs thus obtained were converted to those that would have been obtained using sulfuric acid as solvent using a ;

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2~222~9 ~ calibration curve.
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., :. The amino end group (AEG) concentration was obtained by standard potentiometric ~i titration method. A 3.33% solution of dry polymer or yarn was prepared in 68%
phenol/32% methanol and titrated against 0.02 N hydrochloric acid So apredeterm~ned pH. The AEG was calculated from a calibration curve obtained using polymer chips of known AEGs.
..~, The yarns were knitted into fabrics and dyed using the following procedure. The ~; greige fabrics were preheatset at 193- C for 60 seconds. A dye bath with a liquor ratio of 15:1 was prepared which contained 1% owf Irgalev PBF, 2% owf Am~onium sulfate and 2Yo owf Acet~c acid of a centration of 56%. Critlcal commercial swimwear shades were used to test these samples.

Shade Dye Formula ~ Red 1.0% Intrazone Red Gl9~Xo (Crompton & Knowles) .$ 2.5% Erio Acid Red XB (Oiba Geigy) Blue 2.5% Erionyl Brilliant Blue RL 200% (Ciba Geigy) 1.0% Solophenyl Turquoise Blue GRL 250% (Ciba Geigy) ~yeing was carr~ed out at S6 C for one hour. After dyeing the samples were r~nsed and treated in a bath of 1.0% acetic acid (28~o)~ 3% tannic acid and 4.0%~ixing agent XP-10 (Piedmont Chemical Industries, Inc.) for 30 minutes. These aftertreated samples were rinsed in a bath of 0.5YO Peregal ST with a l;quor ratio of 40:1 at 60-C for 10 minutes. The rlnsed samples were later dried and tested for washfastness.
:'-Dye washfastness of the samples was measured by using a ~cigar bleed" test, described as follows. 2~ x 4~ samples of the dyed fabric were ~rapped in a 2"
x 4" white nylon fabric in the shape of a cigar. The cigar roll kept in a wet bath at room temperature for 24 hours. The fabrics were dried and the level of staining obtained on the white fabric was graded on a scale of 1 through 5, S

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being the least ~tained. Table III shows the cigar bleed test results conductedin examples 1 through 6. No attempts were made to match the shade to the control.

TABLE III
Example Cigar Bleed Rating Blue shade Red shade 1 2.0 2.0 2 2.5 2.5 3 3.0 3.~
4 4.5 3.5 6 4.5 3.5 The percent reflectance, (% R), an indicator of the amount of l~ght reflected from samples dyed with blue shade was measured using a CS-5 Chroma Sensor~
spectrophotometer made by Applied Colored Systems, Inc. The spectrophotometer was run in the specular-included measurement ~ode with an area of view of 0.236" andan an~le of v~ew of 10-; The ratio of the absorption coefficient to the scatterlng coefficient (K/S), an indicator of the degree of the depth of shade was calculated using the Kubleka-Munk approximation:

Table IV depicts the results obtained from the spectrophotometer in examples 1-6. Trist~mulus values and CIE L*~*b* coordinates were calculated from the reflectance data over the range of wavelengths (400 nm to 700 nm). ~L*, a measure of a change in lightness of shade and ~E*9 a measure of an overall colordifference in comparison to the control (example 1) were obtained using standardmethods lF.W. Billmeyer, Jr. and M. Saltzman, "Principals of Color Technology,"
Pub. J. W~ley & Sons, NY (1981)]

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TAB~E IV -~

Example %R K/S ~L ~E
1 6.22 7.06 2 5.14 8.74 -2.60 3.37 3 5.33 B.40 -2.15 3.09 4 4.20 10.92 -5.91 ~.24 4.25 10.78 -6.02 7.30 6 3.18 14.75 -10.7 12.70 A negative ~L* value indicates darker shade as compared to the control. In a separate experiment, attempts were made to match several shades obta~ne~ on the control with those obtained using example 6. To achieve the same shade as the control sample, the amount of dyestuff in the dye bath containing example 6 had to be significantly reduced. Table V indicates the respective starting dyebath concentrations of the dyes after the shades were matched.

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' Shade Color Example 1 Example 6 Difference Red Erio Aeid Red 1) 2.0Yo 0.21% ~90%
Intrazone Red 2) 2.0% 0.92% -54%

Raspberry Telon Fast Blue 3 ) 0.31% 0.17% -46%
Nylomine Red 2CB 4) 1.g1% 0.87% -54%
Telon Ex Yellow 0.013% O.OX -100%
A-3GL 3) Green Acidol Br. Yellow 0.75% 0.39% -48Yo BGX-N 5) ~ .

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Nylon Turquoise HGL 6) 0.30% 0.22% -27%
~; Nylanthrene Pink 0.02% 0.022% +10YO
BLRF 2) ,~
Sky Blue Acidol Br. Blue 0.96% 0.41% q3%
M-5G 5) Erionyl Br. Blue U.43% 0.25~o -42%
~I RL 200~o 1) ~ 1) Ciba Geigy 'J,~' 2) Crompton & Knowles , ``
~ 3) Mobay `~ 4) ICI

5) BASF

6) Miles, Inc.
The cigar bleed test was performed on these color-matched samples. The results ~! of the cigar bleed test as tabulated in Table VI clearly reveal the superior dye fastness of the sample containing TEG~ -~

TABLE VI

Shade C~gar bleed rating Example 1 Example 6 Red 1 3.5 Raspberry 4 5 Green 4 5 Sky Blue 5 5 Examples 7 and 8 in Table VII are results of a separate experiment conducted under processing conditions similar to those in examples 1-6, however, the amount of additives and the polymer viscosities were different. To process example 8, j a homogeneous slurry of TEG, Irganox~ B-1171 and TiO2 was prepared using a Waring i~ blender 1n the rat~o (76% TEG, 14Yo TiO2 and 10% Irganox B1171) and the mixture was injected at the throat of the extruder. The injection method was similar tothe one used in examples 2-6. The rate of in~ection was adjusted so as to get 1.6% TEG, 0.25% Irganox~ B 1171 and 0.3% TiO2 in the yarn.

21222~9 ~ TABLE VII
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Exo Chip RV AEG AEG after heat setting Chip Yarn Chip Yarn 380 F-1 min 380F-2 min 7 BS403F 2.40 2.48 28 24 18 14 8 BS700F~* 2.70 2.65 37 42 36 33 (* ~ 1.6% TEG ~ 0.25~ Irganox~ B 1171~ 0.3YO TiO2) Examples 1 through 8 were kn1tted into fabrics and heat set at 380F for 1 min and 2 mins. The degree of yellowing was measured on a spectrophotometer. ~b values~ndicate the degree of yellowing compared to that of the non-heatset ~abrics.
~: Higher ~b values indicate greater yellowing. Tables VI depicts the ~b values for :~
examples 1-8. ~-TABLE VIII

~b ~ "''~;
Example 380 F- 1 min 380 F-2 min 1 6.03 9.83 2 7.41 10.2 3 10.89 11.64 4 7,09 9.53 ~.10 ~1.19 6 8.50 11.66 7 7.7 12.8 8 5.5 6.6 ~i~
: During dyeing, small aliquo$s of dyebath liquor were sampled at regular intervals for concentration measurement on a precalibrated spectrophotometer. The rate of~:~ dye pick up was thus obtained using 1.5% of tectilon blue dye in the dyebath.
Table IX indicates the amount of dye on the fabric expressed as a percentage.

: 17 :

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~ TA8LE IX
~ .
me (min) Example ~ Example 8 ~:
~j O O O ,--13% 18%
18Yo 38%
45% 69 58% 70~ ;
53X~ 66X
50% 65X ~-5~X 7~% ' ~`
Clearly9 example 8 exhibits a much higher rate of dyeing as well as a greater dye uptake. In another experiment, examples 7 an~ 8 were dyed to saturation and the residual equilibriumdyebath concentration was measured in each case. Th~ amount ~M of dye on the fabr~c was calculated after normalizing for weights of the samples in the baths.
The data in Table X conf~rms the higher amount of dye uptake for the sample f ~ conta~ning TEG and Irganox B1171.
TABLE X

Example DYE SATURATION VALUES
%Dye OWF*
: 8 5.2 OWF- on weight of fabric The colorfastness to water in a chlorinated pool test was conducted on examples: : 7 and 8 using the standard MTCC test method 162^1986 (MTTCC Technical : Manual/1988, 295). The results were compared to the control and graded according to a gray scale of 1-5, 5 indicating least fading in the pool. Results in table XI clearly reveal an enhanced resistance to color fading to water in the ~: 18 ~' :

~ chlor~nated pool test. 2122~D9 TABLF Xl Example Test grade ~urquo~se shade Raspberry shade '.

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Claims (20)

1.
A polyamide fiber, which comprises:
(a) a fiber forming polyamide (b) an additive selected from the group consisting of water, alcohols, amines and mixtures thereof; and (c) a heat stabilizer selected from the group of phenolic compounds, phosphites containing acyl groups and mixtures thereof.

2. The fiber according to claim 1, wherein the fiber forming polyamide is selected from the group consisting of nylon 6/6, nylon 6/9, nylon 6/10, nylon 6/12, nylon 6T, nylon 11, nylon 12, copolymers thereof and mixtures thereof.

3. The fiber according to claim 3, wherein the polyamide is nylon 6 or nylon 6/6.

4. The fiber according to claim 3, wherein the polyamide is nylon 6.

5. The fiber according to claim 1, wherein the alcohols are selected from the group consisting of benzylalcohol, benzoin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, neopentylglycol, glycerin, trimethylolethan, trimethylolpropan, pentaerythritol and mixtures thereof.

6. The fiber according to claim 1, wherein the alcohols are glycols.

7. The fiber according to claim 6, wherein the glycol is triethylene glycol.

8. The fiber according to claim 1, wherein the amine is a mono-or diamine.

9. The fiber according to claim 1, wherein the amine is selected from the group consisting of hexamethylene diamine, meta-xylene diamine, 1,4 bix-aminomethyl cyclohexane, and mixtures thereof.

10. The fiber according to claim 1, wherein the phenolic compound comrises at least one dialkyl hydroxphenyl group, wherein at least one alkyl group is in ortho position to the hydroxyl group.

11. The fiber according to claim 1, wherein the phenolic compound is selected from the group consisting of 2,2' methylene-bix(6-tert. -butyl-4 -methylphenol), 2,2'-methylene-bix(6-tert.-butyl 4 - ethplphenol), 2,2 bis-(3,5-di-tert. butyl-4-hydroxphenyl)-propane 1,3,5-tris-(3,5-di-tert.-butyl -4 hydroxphenyl-propionyl) -hexahydro-s triazine, N,N'-di(3,5,-di-tert. -butyl-4 hydroxphenyl-propionyl-hexamethylenediamine, 1,3,5-tri (-3,5-tert. -butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, pentaerythritol-tetra[3-(3,5-di-tert.butyl-4-hydroxyphenyl) propionate], .beta. (3,5-di-tert.-butyl-4hydroxphenyl)-propionic acid-n-octadecyl ester, thiodiethylene glycol .beta. - [4-hydroxy-3,5-di-tert.-butyl phenyl]
propionate, 2,6,di-tert.-butyl-4-methyl-phenol, 3,9-bis -[1, 1-dimethyl-2-(3, 5-ditert. butyl-4-hydroxy-phenyl) ethyl]
2,4,8,10-tetraoxaspiro-[5,5] -undecaine, polyamides derived from alkylhydroxphenylalkanoic acids with polyamines and mixtures thereof.

12. The fiber accordign to claim 1, wherein the phosphite, containing aryl groups, is selected from the group consisting of tris-(2,5-ditert. - butylphenyl)-phosphite, tris-(2-tert.-butylphenyl)-phosphite, tris-(2-phenylphenyl)-phosphite, tris-[2-(1,1-dimethylpropyl) -phenyl]-phosphite tris-[2-4-di-(1,1-dimethylpropyl) -phenyl]-phosphite tris-(2-cyclohexylphenyl)-phosphite, tris-(2-tert. -butyl-4 phenylphenyl) phosphite, and tris-(2-4-ditert.-butylphenyl)-phosphite

13. The polyamide fiber according to claim 1, wherein the additive (b) is usedin an amount of from about 0.05 to about 4% by weight based on the total weight of the polyamide fiber.

14. The polyamide fiber according to claim 1, wherein the heat stabilizer (c) is used in an amount of from about 0.01 to about 3% by weight, based on the total weight of the polyamide fiber.

15. The polyamide fiber according to claim 1, having a relative viscosity of from about 2.0 to about 3.2.

16. The polyamide fiber according to claim 19 having an amine end group content of from about 15 to about 70 meq/kg.

17. The polyamide fiber according to claim 1, having improved heat stability measured in a spectrophotometric yellowing value .DELTA.b of less than about 8 after two minutes exposure to 380°F.

18. The polyamide fiber according to claim 1, having a dye uptake with a dye saturation value of at least about 3% based on weight of fabric.

19. The polyamide fiber according to claim 1, having an improved dye wash-fastness measured by the cigar bleed test stain rating of at least 3.5 on color matched samples.

20. The polyamide fiber according to claim 1, having a tenacity of from about 2 to about 5.5 g m/den and an elongation of from about 25 to 75%.