US3492368A - Fiber forming linear polyesters with improved dyeability - Google Patents

Description

United States 3,492,368 FIBER FORMING LEN EAR POLYESTERS WITH EMPROVED DYEABILITY Harry W. Coover, Jr., and Frederick B. Joyner, Kingsport, Tenn, assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Continuation of application Ser. No.

560,102, June 24, 1966, which is a continuationin-part of application Ser. No. 232,895, Oct. 29, 1962. This application Jan. 6, 1969, Ser. No.

Int. Cl. C08g 39/10 U.S. Cl. 260857 24 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation of application Ser. No. 560,102 filed June 24, 1966, now abandoned, and a continuation-in-part of application Ser. No. 232,895 filed Oct. 29, 1962, now abandoned.

This invention relates to novel linear polyester compositions having improved dyeability adapted for formation into fibers, filaments and yarns and other shaped articles. More particularly the invention relates to modifications of linear polyesters to provide compositions readily spinnable into fibers and yarns susceptible of permanent dyeing to deep shades by a wide variety of dyes including premetallized and acid wool dyes as well as conventional disperse and other conventional polyester dyes.

Those high-molecular weight, fiber-forming polyesters which have met with commercial success in the form of synthetic fibers such as Dacron or Kodel polyester fibers are relatively insoluble, hydrophobic materials. Since they are not readily permeable to water, they cannot be dyed satisfactorily by the ordinary inexpensive dyeing procedures. Since they lack reactive groups such as those that abound in cellulosic and protein fibers, they can be dyed satisfactorily only by a limited class of disperse dyes. Usually it is necessary in obtaining even only light and medium shades to employ high temperature dyeing procedures which are operated at temperatures above 100 C. or with the use of carriers or the use of both high temperature and carriers. Since many dyestuffs decompose at temperatures above 100 C. (e.g., some blues will redden), careful selection of dyestufis must be made for high-temperature dyeing of polyester yarns and fibers. This markedly limits the utility of these materials in the textile field, because they cannot be dyed readily on conventional commercial dying equipment. In addition, carrier dyeing involves considerable extra cost, since (1) the carriers are themselves expensive, (2) the dyed yarns have a pronounced tendency to retain the odor of the carrier and require very thorough washing to eliminate it and (3) residual carrier left in the fiber seriously impairs the light tastness of the dyed material. The hydrophobic nature of linear polyesters is also manifested in their low moisture regain. The low moisture regain of these materials is conducive to the development of static atent O during processing operations, such as picking, carding, winding and weaving. Although static troubles may be substantially eliminated during processing operations by the application of lubricants and hydrophilic sizing materials, garments produced from linear polyester yarns tend to develop static charges during wear which attract dirt, dust, lint and other materials, thereby causing the fabrics to become rapidly soiled. Furthermore, unmodified polyester fibers, when dyed with the conventional disperse or polyester dyes, have poor resistance to dry cleaning solvents such as trichloroethylene, experience having shown that dry cleaning solvents of this type often extract the dyestuffs from the fibers causing a reduction in shade or producing a mottled effect. As will be more fully set forth hereinafter, the present invention is directed to overcoming these difficulties and to providing polyester fibers and yarns which can be readily and satisfactorily dyed with a wide variety of dyes including premetallized and acid wool dyes as well as disperse dyes.

The problem of dying fibers from hydrophobic polymeric compositions has of course been a long standing one in the art. In fibers produced from polyolefins, for example, the problem has been aggravated due to the specific properties of this material. For example, French Patent 1,190,703 refers to the addition to polypropylene and other polyolefins of homopolyamides such as polyepsilon-caprolactam and polyhexamethylene sebacamide and the like to provide a dye receptor in the polyolefin material to make fibers produced from it dyeable.

Facilitating the dyeing of various objects such as filaments, yarns, fibers, films and other structures composed of regenerated cellulose by adding a synthetic linear polyamide to a viscose spinning solution and then forming the desired objects from such solutions by the usual wet spinning procedure has been suggested in US. Patent to Watkins, 2,265,559 but no reference is made in this disclosure to any problem dealing with the dyeing of polyesters. The linear polyamides referred to are stated to be non-fiber forming and having intrinsic viscosities not exceeding 0.6.

Other prior art relates to homogenous blends of polyesters and polyamides, including copolyamides such as those of value in the practice of the instant invention. For example, Australian Patent 132,546 refers to the combining of polyesters with other polymeric materials by heating in the melt until a homogeneous blend is obtained. However, when blends of polyesters and copolyamides are prepared in accordance with the teachings of such prior art, an interaction occurs between the two polymers to produce a new and entirely dilferent polymeric species as is evident from the homogeneity and single, relatively low melting points of the so-called blends. Such homogenous blends of polyesters and copolyamides have no practicable textile utility and do not provide the surprising and unexpected advantages of the compositions of the present invention as will be more fully set forth hereinafter.

It is accordingly a principal object of this invention to overcome the above-mentioned difliculties encountered in the dyeing of polyester (including copolyesters) fibers, yarns, fabrics, film an other shaped articles and to pro vide a practical and satisfactory means of permanently dyeing a polyester fiber-forming polymer (including copolymers) such as polyethylene terephthalate and other fiber-forming polyesters including copolyesters.

Another sbject is to provide polyester compositions adapted to be readily formed into fibers, films, rand yarns 'which are susceptible of permanent dyeing by premetallized, acid wool, disperse and other dyes.

Another object is to provide polyester fibers, filaments, and yarns susceptible of being dyed by premetallized,

acid wool, disperse and other dyes to deep shades which are essentially gas fast, light fast, wash fast and have little or no tendency to crock of bleed.

A specific object is to provide polyester fibers which can be dyed to deep shades by premetallized and comparable dyestuffs and still have excellent resistance to the action of dry cleaning solvents such as perchloro ethylene.

A still further object is to provide modified polyester textile fibers having improved physical properties, re sistance to soiling, and improved moisture regain.

Other objects will appear hereinafter.

These objects are accomplished by the following invention which is based on the discovery that certain polymeric blends of fiber-forming linear polyesters with certain condensation copolyamides or homopolya-mides can be melt spun or formed into high strength fibers, filaments, and yarns having excellent afiinity for premetallized and acid wool dyes as well as disperse dyes and other polyester dyes. The dyed materials obtained thereby exhibit excellent light and gas fastness, and are resistant to the action of perchloroethylyene or other dry cleaning solvents.

The copolyamides of value in the practice of our invention are derived preferably from aminoacids or their lactams and/or polymethylenediammonium salts of di carboxylic acids. These copolyamides may be prepared by any of the known procedures such as that described by Sonnerskog in Acta Chemica Scandinavica, 10 (1956), No. 1, 113-117 for producing 6/66 copolyamides.

According to the invention a copolyamide of the type indicated above composed of repeat units selected from the group consisting of wherein R, R and R are divalent hydrocarbon radicals, and in which R contains 3-11 carbon atoms, such as trimethylene, tetramethylene, pentamethylene, hexamethylene, phenylene, xylylene, cyclohexylenedimethylene, and the like, R contains from 1-10 carbon atoms such as methylene, ethylene, trimethylene, phenylene, xylylene, cyclohexylenedimethylene, and the like, and R" contains from 2-12 carbon atoms such as ethylene, trimethylene, tetramethylene pentamethylene, hexamethylene, phenylene, xylylene, cyclohexylenedimethylene and the like, is blended in a manner which will be more fully set forth hereinafter, with a linear fiber-forming polyester such as polyethylene terephthalate.

The end-groups of the preferred copolyamides may be amino, acyl, aryl, carboxyl, arnido, alkoxyl and the like. In general, amino end-groups are preferred when it is desired to impart enhanced affinity for acid dyes to the modified polyester fibers. In most cases, however, the end-groups have very little influence on the dye receptivity of the copolyamide, or on the dyeability of the polyester fibers modified therewith.

These copolyamide modifiers employed in accordance with our invention are advantageously added to the polyester so as to produce a fiber-forming composition containing 1-25 percent and preferably 5-20 percent by weight of the modifier and these modifiers have the following properties:

(a) Soluble in or softened by either water or alcoholwater mixtures.

(b) A melting point within the range of 140-260" C., and preferably within the range of 150-250 C.

(0) An inherent viscosity (in 60/40 phenol-tetrachloroethane measured at about 25 C.) within the range of 0.6 to 2.0 and preferably within the range of 0.8 to 1.5.

The ho-mopolyamides of value in the practice of our invention include polylactams comprised of the following repeating unit:

and polyamides comprised of repeating units of the following type:

wherein R, R and R are divalent hydrocarbon radicals, and in which R contains 3-11 carbon atoms, such as trimethylene, tetramethylene, pentamethylene, hexamethylene, phenylene, xylylene, cyclohexylenedimethylene, and the like, R contains from 1-10 carbon atoms such as methylene, ethylene, trimethylene, phenylene, xylylene, cyclohexylenedimethylene, and the like, and R" contains from 2-12 carbon atoms such as ethylene, trimethylene, tetramethylene, pentarnethylene, hexamethylene, phenylene, xylylene, cyclohexylenedimethylene and the like. R may also be a divalent radical containing a heteroatom which is chemically inert under the process conditions used to prepare the heterogeneous blends of this invention. For example, homopolyamides in which R is an oxydipropyl group are quite useful when they meet the specifications set out below.

The end-groups of the preferred homopolyamides are similar to those given above for the copolyamides. In general, however, the end-groups have very little influence on the dye receptivity of the homopolyamides (as is the case with the copolyamides) or on the dyeability of polyester fibers modified therewith.

These homopolyarnide modifiers employed in accordance with our invention are advantageously added to the polyester so as to produce a fiber-forming composition containing 1-40 percent by weight of the homopolyamide with the preferred polyarnide concentration being in the range of from 10-30 percent. However, for example, in a polymer composition useful for forming fibers for automotive tire cords, a blend having a concentration of homopolyarnide of as much as percent may be advantageous in some instances. The homopolyamide modifiers useful in this invention have the following properties:

(a) Insoluble in alcohol-water mixtures.

(b) A melting point within the range of 160-320 C., and preferably within the range of 175-300 C.

(c) An inherent viscosity (measured at about 25 C., in 60/40 phenoltetrachloroethane) within the range of 0.2 to 2.0, and preferably within the range of 0.6 to 1.5.

Polyester fibers of our invention modified by the polyamides having the above properties are generally dyeable with premetallized dyes to deep shades which have:

(a) Light-fastness of greater than 20 hours exposure in a Fade-O-Meter.

(b) Excellent resistance to trichloroethylene (no substantial reduction in depth of shade after exposure for 4 hours at F.).

Especially advantageous modified terephthalate polyester fibers can be made according to this invention which are characterized by the following properties:

(a) Moisture regain of about 0.3 to about 3.0 percent at 65 percent relative humidity and 70 F.

(b) Shrinkage in air at C. of not more than 15 percent.

(c) Tenacity at 21 C. of at least 1 gram per denier.

(d) Elongation at 21 C. of at least 7 percent.

(e) Elastic modulus at 21 C. of at least 8 grams per denier.

DEFINITIONS In certain of the examples, tables and other description given herein We have referred to certain physical proper ties of the compositions and filaments, fibers and yarns produced therefrom. As an aid to a more lucid and accurate disclosures of our invention the following definitions are given:

Inherent viscosity (I.V.).This property, represented by {1 which is used as a measure of the degree of polymerization of a polymeric compound is calculated from the equation:

wherein 1;, is the ratio of the viscosity of a dilute (approximately .25 percent by weight) solution of the polymer in a solvent composed of 60 percent by weight of phenol and 40 percent by weight of tetrachloroethane to the viscosity of the solvent itself, and C is the concentration of the polymer in grams per 100 cubic centimeters of the solution.

Tenacity or tensile strength.This is a measure of the strength of the fiber, filament or yarn under study. It is expressed in grams per denier (g./d.) and is calculated by dividing the initial denier of the fiber under study into the tension (in grams) required to break the yarn.

Elongation.-This is a measure of the extent to which a fiber, filament or yarn is stretched when it breaks. It is expressed as a percentage and is calculated by dividing the original length of the sample into the increase in length and multiplying by 100.

Modulus of elasticity.As used herein modulus of elasticity may be defined as the tension in grams per initial denier per percentage elongation necessary to stretch the sample to the stated percentage elongation.

Melting Point.The melting point of the polymers herein referred to are determined by the well-known technique of differential thermal analysis.

Melt viscosity.The viscosity of a material is the internal fluid resistance of the material which makes it resist a tendency to flow. Since molten polymers in general are not strictly Newtonian liquids, their viscosity will vary with shear rate. Accordingly, their flow characteristics must be described in terms of the apparent melt viscosity at the shear rate and temperature in question. Measurements of the melt viscosity are usually made with a Williams plastometer (parallel plate type) or a Brookfield viscometer (rotating cylinder type). Melt viscosity is usually expressed in poises.

Accelerated dry cleaning test.-Dry cleaning tests were run in accordance with A.A.T.C.C. procedure 85-1960T.

Color fastness to light.Light fastness was determined in accordance with A.A.T.C.C. procedure 16A-1960 using a Fade-O-rneter of the type described therein.

The modified polyester fibers and yarns of this invention, for example, may be drawn to give the same high tenacities, low shrinkage, and other excellent properties found in unmodified polyester yarns. This was quite surprising since, for example, the copolyamides preferred in the practice of this invention themselves have relatively low crystallinities, and, as a result give fibers which possess low tenacities, relatively high shrinkage, and have no commercial value. It would have been predicted, contrary, to fact, that these materials, when used to modify polyesters for fibers and yarns, would have deleteriously affected the properties of the yarns.

Although unmodified polyesters, for example, show virtually no afiinity for many types of dyestuffs, they can be dyed with selected disperse dyes to weak shades having adequate fastness properties, but require the use of carriers for moderate to deep shades. Surprisingly, it was found that the modified fibers and yarns of this invention could be dyed to deep, fast shades by conventional procedures using an aqueous dye-bath, although .many of the copolyamides used as the modifiers are usually soluble in hot water or alcohol-water mixtures.

It would have been predicted that much of the copolyamide modifier would have been leached from the fiber during the dyeing operation. On the contrary, substantially no modified is lost during the dyeing operation. It isp referred that the copolyamide have a water absorption at saturation of greater than 7 percent to about 14 percent.

As indicated above, the copolyamide and homopolyamide modifiers useful in the practice of this invention have melting points in the range of to 260 C. and to 320 C., respectively, with a preferred range of 150 to 250 C. and to 300 C., respectively (determined under nitrogen, carbon dioxide or other inert atmosphere). Polyamides (hereinafter used to refer to both copolyamides and homopolyarnides) have melting points substantially above or below these respective ranges cannot be readily blended with the polyesters to give satisfactory dispersions. Fibers obtained from polyesters modified with the higher melting polyamides often show the uneven dyeability usually associated with poor dispersions of the modifier in the polyester.

Among the copolyamides which we have found to have particular efficacy in carrying out our invention as described above are the 6/66 type copolyamides derived from epsilon-caprolactam and hexamethylenediammonium adipate, and the 66/610 type copolyamides derived from hexamethylenediammonium adipate and hexamethylenediammonium sebacate and the 6/66/610 terpolyamides derived from epsilon-caprolactam, hexamethylenediammonium adipate and hexamethylenediammorium sebacate. These copolyamides may be structurally illustrated as follows- 6/66 copolyamides are comprised of the following units:

6/610 copolyamides are comprised of the following unltsz 66/ 610 copolyamides are comprised of the following units:

6/66/ 610 terpolyamides are comprised of the following units:

Other modifiers which are of particular value in our invention are copolymides containing repeat units which include carbocyclic structures such as those derived from terephthalic acid, meta-xylene-alpha, alpha'-diamine, and l,4-cyclohexanebismethylamine. copolyamides of this type are illustrated in the following groups I, II, III of polymers made up of 6 units or 610 units with other repeat units containing such carbocyclic structures:

(m-xylylene adipamide unit) The copolyamides as employed in our invention may have inherent viscosities as determined in 60/40 phenol/tetrachloroethane of 0.6 to 2.0 or greater, although inherent viscosities of 0.8 to 1.5 are preferred in most cases. The melt viscosities of the copolyamides under melt spinning conditions should be compatible with the melt viscosities of the polyester resins with which the copolyamides are to be blended. That is, the melt viscosity of the copolyamide should be substantially the same as or less than that of the polyester.

Suitable homopolyamides useful in the practice of this invention would include poly(epsilon-caprolactarn), polyhexamethylene adipamide, polyhexamethylene sebacamide, polydecamethylene sebacamide, polynonaimethylene azelamide, olyhexamethylene suberamide, poly(1,4-cyclohexylenedirnethylene) suberamide, poly(m-xylylene sebaca'mide), polyoctamethylene succinamide, poly(11- aminodecanoic acid), etc.

As pointed out herein above the copolyamide modifiers are substantially less crystalline than the corresponding homopolymers made from the same intermediates. The polyamide homopolymers, such as polylfepsilon-caprolactam), poly(hexamethylene adipamide), poly(l,4-cyclohexylenedimethylene suberamide), etc., provide other improvements in polyester fibers and yarns that are not afiorded by the copolyamide modifiers of this invention. The homopolymers are usually high in tensile strength and as such would be good for tire fibers blended with polyesters in accordance with this invention. Such blends would reduce the flat spots that result from the use of polyamide fibers alone. Additionally, homopolya mides in blends with polyesters would improve adhesion with rubber, as polyesters alone do not adhere well to rubber.

In accordance with the present invention, it has been found that a linear, fiber-forming polyester properly blended or admixed with a polyamide of the types described above can be readily melt spun into fibers and yarns which can be dyed with premetallized dyes to deep shades having excellent light and gas fastness and excellent resistance to perchlorethylene and other dry cleaning solvents. In addition, disperse dyes can be employed to produce dyed materials free from the dye-bleeding and crocking problems encountered when these dyes are used on the unmodified polyesters. The polyamide-modified polyester fibers and yarns of this invention may be processed into garments and fabrics having a greatly diminished tendency to develop electric charges and, therefore, having improved resistance to soiling. The dyeing process can be carried out using conventional procedures either with or without carriers. As indicated above, the polyester blends useful in the practice of this invention may contain from 1 percent to 40 percent or more of the polymeric modifier by weight (in the case of homopolyamides). Any of the known blending procedures may be used to mix the polyester and copolyamide, such as extrusion, rolling, Banbury mixing, etc. In general, however, suitable fibers and yarns may be obtained by melt spinning a mechanical blend of pellets of the two resins.

Usually, it is preferable to prepare the modified polyester compositions from polyesters having an inherent viscosity of from 0.6 to 1.5. Polyesters having viscosities above or below this range can be used in preparing the modified compositions, but then it is usually difficult to realize optimum melt spinning characteristics and fiber properties.

Although the particular method of blending is not critical and any conventional procedure which will result in thoroughly mixing the modifier with the polyester may be employed, two conditions of the blending are important. First of all, it is important that all traces of moisture be removed from the polymeric ingredients and from the apparatus used to prepare the blends of this invention. The ingredients and the apparatus should be rigorously dried prior to heating and blending. Adequate drying can be achieved by heating the polyester and polyamide separately or in admixture, under reduced pressure (preferably below a pressure of 10 mm. Hg) and at a temperature above C. but below the melting point of any of the ingredients. The time of drying will, of course, depend upon the moisture content of the polymers and on the temperature of drying. At 100 C., drying should be carried out for at least 8 hours. At C. or above, drying periods of 2 to 4 hours are usually sufi'icient.

A second important feature of this invention is the time of heating and/ or of blending at temperatures about the melting points of the polymer ingredients. Preferably, the time of heating and/or blending, at temperatures above the respective melting points should not exceed one hour. In the case of certain polyester-polyamide combinations it is possible to heat and/or blend for longer time at temperatures above the melting points, if it is so desired. However, since it is not entirely predictable which combinations can be kept above the melting points for long periods, it is best to limit this time to a. maximum of one hour in every instance.

As mentioned previously the method of blending is not critical and any conventional method may be used. For example, a pre-mix of the desired proportions of finely divided copolyamide and finely divided polyester may be prepared, mechanically mixed and spun directly to produce dyeable fibers. Films or sheets may likewise be produced in this manner. In another version of the blending technique the polyamide in the form of rods measuring /8 inch in diameter and A; inch long may be fed by a Vibra Screw into a descending stream of similar pellets of the polyester material being fed to a standard type of heated extrusion machine. Blending is accomplished by the action of an internally rotating screw which forces the molten mixture through a spinneret or other appropriate device for the formation of fibers or other products. In still another variation, as explained in the examples to follow, a master batch containing, for example, 50 percent by Weight of finely divided copolyamide and 50 percent by weight of finely divided polyester or other proportions may be formed by placing the mixture in a Banbury mixer and operating the mixer so as to melt and blend the two components. A predetermined amount of this blend in finely divided form may then be added in the desired proportions to the polyester and the mixture melted and melt spun or extruded into fibers or other shaped objects as may be desired. In any event the material to be blended should preferably be in a finely divided form such as powder, granules, pellets or the like.

The polyesters employed in practicing this invention include those which are well known in the art as exemplified by U.S. Patent 2,465,319, US. Patent 2,901,466, US Patent 2,744,089 and US. Patent 3,018,272. It is to be understood that we use the term polyester in our specification and claims as including both homopolyesters and copolyesters, except where specific reference to one or the other is given.

The blends of fiber-forming polyesters and polyamides prepared in accordance with our invention are physical mixtures consisting of two discrete phases, one dispersed in the other with no interaction between the two, as distinguished from the homogenous blends of the prior art. This is readily apparent when, for example, fibers melt spun from these blends are examined in cross section by means of a polarizing microscope. These discrete phases can readily be identified by other microscopic techniques, such as Leitz phase contract and elec tron microscopy. The existence of two discrete phases may also be shown by differential thermal analysis (DTA) which indicates that the melting points of the polyester phase and the polyamide phase remain substantially unchanged.

As indicated above it is necsesary to minimize the length of time that the blends are maintained in the molten state either during melt blending operations such as in a compounding extruder, or during melt spinning. We have found that by removing all traces of moisture from the polymeric ingredients, we may maintain the blends in the molten state at temperatures reasonably in excess of 250 C. for periods of up to one hour without any degradation or detectable chemical interaction between the two ingredients. As a result, the product thus formed is completely heterogenous, having a distinct polyamide phase dispersed in a polyester phase. Preferably the blends are maintained in the molten state for periods no longer than 30 minutes; however, the blends can be so maintained for up to an hour without any deleterious effect.

The following examples will readily serve to illustrate the novel features of this invention. The preferred embodiments set out below are merely for purposes of illustration and are in no way intended as a limitation of the present invention.

EXAMPLE 1 In a 500-ml. Teflon-coated flask were placed 48 g. of poly(ethylene terephthalate) (I.V.=0.69) and 12 g. of an amide copolymer containing 22 mole percent of the units derived from poly(hexamethyleneadipamide) with 78 mole percent of the units derived from e-caprolactum (I.V.=0.99). The flask was fitted with a metal, sweep stirrer and a head containing a stirrer bearing and side arms for nitrogen inlet and outlet. The flask was evacuated and purged with dry nitrogen three times and finally was left under vacuum and heated at 132148 C. for 4 hours under vacuum of about 2 mm. and then removed from the bath. The temperature of the bath was raised to 278 C. and the flask and contents were placed in the bath while still under vacuum and the contents were blended with slow stirring for a total of 28 minutes. During this time the temperature of the heating bath varied from 269-283 C. At the end of this heating period, the flask was removed from the bath and allowed to cool under vacuum. The polymer had an inherent viscosity (I.V.) of 0.83 and the differential thermal analysis (DTA) chart showed a small melting peak at 173 C. and a main peak at 247 C.

The above polymer was ground to pass 20 mesh, and 5 g. samples were placed in individual tubes and dried under vacuum (1 mm.) at 150 C. in a heating block for 4 hours and removed from the block. The block was raised to 280 C. and the tubes under nitrogen were placed in the block and withdrawn at the times indicated in the table below and the I.V. and DTA melting points determined:

Heating time,

minutes I.V. (1) (2) 1 Shoulder.

The above data indicate that the polymer blend contains components characteristic of both the amide copolymer and the poly(ethylene terephthalate) and that the blend retains these peaks without significant degradation of polymer when heated at 280 C. for periods as long as one hour.

EXAMPLE 2 In a -ml. flask equipped with metal stirrer and glass head were placed 18 g. of polyethylene terephthalate and 2.0 g. of Zytel 101 (Nylon 66). The flask was evacuated and twice purged with dry nitrogen. The flask was then placed in a Woods metal bath at 150. C. and heated for 2 hours and 20 minutes with stirring under vacuum. The system was then brought to atmospheric pressure by releasing the vacuum to dry nitrogen, and the temperature of the bath was increased to 276 C. The flask and contents were stirred 20 minutes at 273 280 C., removed from the bath and allowed to cool under the nitrogen atmosphere. The inherent viscosity was 0.70. Melting of the polymer in the DTA apparatus showed a large peak at 241 C. and a small peak at 257 C.

The Zytel 101 alone showed a single DTA melting peak of 258 C. and the poly(ethylene terephthalate) had a single melting peak of 243 C.

EXAMPLE 3 Example 2 was repeated using the same apparatus and materials, but with a different heating cycle. The flask and contents were heated in a Woods metal bath at 198 C. for 3 hours with stirring at 18-19 mm. in a current of nitrogen. Then, the flask and contents were removed from the bath and allowed to stand 15 minutes at about 19 mm. in a current of nitrogen. The flask and contents were then placed in a metal bath at 274 C., and heated at 274280 C. for 3 hours with stirring at 19-20 mm. in a current of nitrogen. At the end of 3 hours, the flask and contents were removed from the bath, the vacuum was released to nitrogen, and the flask was allowed to cool in a nitrogen atmosphere. The inherent viscosity of the polymer product was 0.75. A single peak at 238 C. was obtained when the polymer was melted in the DTA apparatus.

This example is included to indicate what might be inferred from the prior art and the undesirable results obtained.

EXAMPLE 4 Several compositions comprising poly(1,4-cyclohexylenedimethylene terephthalate) of inherent viscosity 0.8 and polyhexamethylene adipamide (M.P. 265; inherent viscosity, 1.27) were prepared by mechanically blending granules of the two polymers. The mechanical blends were then dried by heating at C. under high vacuum (1-2 mm. Hg pressure) for 1 hr. Next they were fed to an extruder and melt spun into 50-filament yarns having the properties shown below.

All of the yarns thus formed dyed readily with premetallized dyes such as C.I. Acid Blue 168 and Cl. Acid Green 43, whereas, the unmodified polyester yarn showed no tendency to take up these dyes under similar conditions. Deep shades were also obtained with disperse dyes, such as C.I. Disperse Yellow 33 and Cl. Disperse Blue 11. Similar yarns (12 den./fil., textured) are especially suited for carpets, since they show high compressional resiliency as indicated by the cylinder-plug test and work recovery measurements.

I II III IV V 100 95 90 85 80 4. 8 2. 4 2. 9 3. 0 13. 4 2. 45 3. 07 2. 56 2. 88 3. 52 Elongation, percent 22.0 16 17 18 7 Elastic modulus. percent 33. 6 29. 9 21.0 29. 1 44. 2

EXAMPLE 5 A mixture of 8.5 parts of poly(ethylene terephthalate) having an inherent viscosity of 0.7 and a melting point of 266 C. and 1.5 parts of poly(e-caprolactam) having a melting point of 221 C. and an inherent viscosity of 0.9 were heated under nitrogen at 300 C. for 15 min. The resulting blend was heterogeneous and showed two melting points (by DTA) as follows: 251 C. corresponding to the polyester phase; and, 216 C. corresponding to the polyamide phase. This blend was readily melt spun into multifilament yarns having good aifinity for premetallized dyes and a sticking temperature above 400 F.

When a comparable mixture of poly(ethylene terephthalate) and poly(e-caprolactam) was heated for 1 hour under similar conditions, a homogeneous blend having only one melting point at 247 C. was obtained. This blend could not be melt spun into multifilament yarns, since the extruded filaments were too brittle.

This example readily shows the adverse effects of no drying or of insufficient drying of the ingredients. When the undried blend is maintained in the molten state for one hour, degradation and homogenation occur.

EXAMPLE 6 A mixture of 9.0 parts poly(ethylene terephthalate) having a melting point of 243 C. and 1.0 part polyhexamethylene adipamide having a melting point of 258 C. was dried by heating at 200 C. for 3 hr. at a pressure of 15-18 mm. of mercury in a current of dry oxygen-tree nitrogen. The mixture was then heated to 275-285 C. in a current of dry, oxygen-free nitrogen at the same pressure for 3 hrs. The resulting blend was completely homogeneous and showed a single melting point at 240 C. and an inherent viscosity of 0.62. This blend could be melt extruded into filaments, but the filaments had low tenacities and poor shrinkage characteristics.

EXAMPLE 7 Example 6 was repeated except that the drying step was carried out at 150 C. for 2 hrs. at a pressure of less than 1 mm. of mercury and melt blending was carried out at 275-285 C. for only 20 min. The resulting blend was heterogeneous and showed two melting points (DTA)- one at 242 C. for the original polyester and one at 256 C. for the original polyamide. Heterogeneous blends of this type were melt spun into multifilament yarns.

Knit tubes prepared from these yarns all dyed to deep shades with premetallized dyes such as C.I. Acid Green 43 and Neutracyl Red B (Du Pont). Conventional dyeing techniques were used and the shades obtained have excellent light fastness and resistance to dry cleaning solvents. These yarns can be dyed also with the conventional polyester dyes; that is, disperse dyes such as CT. Disperse Blue 11 and Cl. Disperse Yellow 33. On the other hand,

knit tubes of the unmodified polyester yarn had no afiinity for premetallized dyes.

EXAMPLE 8 A mixture of parts poly(1,4-cyclohexylenedimethylene terephthalate) of inherent viscosity 0.8 and 20 parts poly(m-xylylene sebacamide) was dried under high vacuum at C. for 24 hrs. The dried mixture was then fed under an atmosphere of dry, oxygen-free nitrogen to an extruder and melt spun into rnultifilament yarn having a tenacity of 1.96-2.56 g./den., an elastic modulus of 27-41 g./den., and an elongation of 7-18%. Knit tubes prepared from this yarn were easily dyed to deep shades with premetallized dyes such as Cl. Acid Green 43, Cl. Acid Blue 168 and Neutracyl Red B (DuPont); whereas, knit tubes prepared from the unmodified polyester yarn show no tendency to take up these dyes under similar conditions. Disperse dyes, such as Cl. Disperse Blue 11, could also be used to dye the modified yarn. All dyed samples of the modified polyester yarn show very good fastness to ultraviolet light in the Fade-O-meter for 20 hrs. In addition, shades obtained with the premetallized dyes were fast to all conventional dry cleaning solvents.

Microscopic examination of the modified polyester yarn in cross section, using either a Leitz phase-contrast microscope or an electron microscope, showed the yarn to be composed of a heterogeneous mixture of the polyester and the polyamide. Further, differential thermal analysis disclosed two melting points for the fiberone corresponding to that of the unchanged polyester in the blend and the other corresponding to that of the unchanged polyamide modifier.

Other polyamides which give similar results when used in place of the poly(rn-xylylene sebacamide) were:

(a) Polydecamethylene sebacamide (b) Polynonamethylene azelamide (c) Poly(1,4-cyclohexylenedimethylene) suberamide (d) Poly(x-aminoundecoic acid) EXAMPLE 9 Example 8 was followed using poly(1,4-cyclohexylenedimethylene) (83% terephthalate, 17% succinate) as the fiber-forming polyester. The resulting yarn had very good afiinity for both prernetallized and disperse dyes when dyed using conventional dyeing procedures, without any need for pressure or unusually high temperatures.

EXAMPLE l0 Eighty parts of poly(l,4-cyclohexylenedimethylene) (87% terephthalate, 17% isophthalate) were mechanically blended with 20 parts of poly(e-caprolactam) and dried at 100 C. under vacuum for 24 hrs. The mixture was then extruded in a /4-in. diameter rod, pelletized, and melt spun into multifilament yarn having a tenacity of 2.17-3.07 g./ den. and an elongation of 17-25%. Knit tubes from this yarn had excellent afiinity for premetallized dyes; whereas, yarn from the unmodified polyester shows little or no tendency to take up these dyes. Dyed samples of the modified polyester yarn also had excellent resistance to dry cleaning solvents, including trichloroethylene, as well as excellent fastness to ultraviolet light.

EXAMPLE 11 Eighty-eight parts of polypentamethylene (83% 4,4- sulfonyldibenzoate, 17% succinate) were mechanically blended with 12 parts of polyhexamethylene sebacamide and the blend dried at C. under reduced pressure for 18 hrs. The dried mixture was then melt spun into fibers as described in Example 8. The resulting polyamidemodified polyester fibers dyed readily with premetallized dyes to light-fast shades.

EXAMPLE 12 A mixture of 60 parts poly(1,4-cyclohexylenedimethylene terephthalate) having an inherent viscosity of 0.85 and 13 40 parts polyhexamethylene adipamide having an inherent viscosity of 1.4 and a melting point of 265 C. were mechanically blended and dried at 140 C. at a pressure of 10 mm. of mercury for 3 hrs. This mixture was then fed under dry nitrogen to an extruder and melt spun into continuous filament yarn which was drafted to provide yarns having tenacities of 3-5 g./ den. Microscopic examination of cross sections of this polyamide-modified polyester fiber showed the heterogeneity of the polymer blend.

EXAMPLE 13 Example 8 was followed using 85 parts polyethylene (terephthalate 97%, sulfoisophthalate 3%) as the polyester and 15 parts of polyhexamethylene suberamide as the polyamide modified. The resulting modified yarns dyed readily in aqueous boiling dye baths containing C.I. Acid Green 43 and Cl. Disperse Yellow 33. The dyed materials showed no tendency to crock and substantially no loss of dye in sublimation or dye bleeding tests.

EXAMPLE 14 Several compositions comprising poly(1,4-cyclohexylenedimethylene terephthalate) of inherent viscosity 0.81 and a 6/66 copolyamide (M.P. 158 C.; inherent viscosity 1.02) derived from 78 mole percent of e-aminocaproic acid (lactam) and 22 mole percent of hexamethyleneammonium adipate were prepared by mechanically blending dried pellets of the two polymers. These compositions were then melt spun into 50-filament yarns having the properties shown below.

Knit tubes prepared from these yarns, all dyed to deep shades with premetallized dyes such as C.I. Acid Green 43, Cl. Acid Blue 168 and Neutracyl Red B (Du Pont), whereas, knit tubes prepared from the unmodified polyester yarn showed no tendency to take up these dyes under similar conditions. Disperse dyes, such as C.I. Disperse Yellow 33 and Cl. Disperse Blue 11, could be used to produce deep shades from the aqueous dye baths at boil, whereas, pressure dyeings at 120 C. were required to produce even medium shades on the unmodified polyester yarn. All dyed samples of the modified polyester yarns showed excellent fastness to ultraviolet light in the Fade-O-Meter for hours.

Similar results were obtained with 6/ 66 copolyamide modifiers of 70 mole percent and 35 mole percent of the epsilon-aminocaproic acid unit (6-unit) with 30 mole percent and 65 mole percent of the 66-unit (from hexamethylenediammonium adipate), respectively.

EXAMPLE 15 .A mixture of 9 parts of dry poly(ethylene terephthalate) having an inherent viscosity of 0.74 and 1 part of dry 66/610 copolyamide (I.V.=0.85; M.P.=192 C.) prepared from 30 weight percent of hexamethylene diammonium adipate and 70 weight percent of hexamethylenediammonium sebacate was prepared by mechanically blending pellets of the two polymers. The mechanical blend was then melt-extruded into fii-inch rod using a 1.25-inch Modern Plastics Machinery extruder and then was chopped into pellets having a length of about 43- inch. The resulting composition was then melt-spun into SO-filament yarn. This modified polyester yarn was knitted into a sock, or tube, which was used in dyeing tests. Excellent dye afiinity for premetallized, acid, and disperse dyes was demonstrated by the deep shades ob tained with Cl. Acid Green 43, Neutracyl Red B (Du Pont), C.I. Disperse Yellow 33 and Cl. Blue 11. Conventional dyeing techniques using aqueous dye baths at boil were employed. Deep shades having excellent fastness properties were obtained without the need for high pressures or carriers in the dyeing operation.

The above copolyamide-modified yarn showed a moisture regain of 0.76 percent at 65 percent RH. and 70 F. as compared with only 0.4 percent for unmodified poly(ethylene terephthalate) yarn.

Other copolyamide modifiers which, when used in place of the above 66/ 610 copolyamide, gave similar results were:

(a) 66/610 copolyamide (M.P. 240 C.) derived from weight percent of hexamethylenediammonium adipate and 15 weight percent of hexamethylenediammonium sebacate.

(b) 6/66/610 terpolya-mide (M.P. 196 C.) derived from 15 weight percent of E-aminocaproic acid, 70 weight percent of hexamethylenediammonium adipate and 15 Weight percent of hexamethylenediammonium sebacate.

(c) Copolyamide (inherent viscosity=1.4) derived from 80 mole-percent of e-aminocaproic acid (lactam) and 20 mole percent of m-Xylylenediammonium adipate.

(d) Copolyamide (inherent viscosity=0.71) derived from 20 mole percent of tetramethylenediammonium oxalate and 80 mole percent of decamethylenediammonium adipate.

EXAMPLE 16 Example 14 was followed using poly(pentamethylene 4,4-sulfonyldibenzoate) as the fiber-forming polyester. The resulting yarns showed excellent afiinity for perrnetallized and disperse dyes using conventional dyeing procedures Without the need for pressure (high temperatures) or carriers.

EXAMPLE 17 Example 15 was followed using polyethylene(terephthalate 97 percent, sulfoisophthalate 3 percent) as the polyester. The resulting modified yarns dyed readily in aqueous boiling dye baths containing Neutracyl Red B, C.I. Acid Green 43, and Cl. Disperse Yellow 33. These yarns showed a 70 to 100 percent greater moisture regain than the unmodified polyester yarn.

EXAMPLE 18 Seventy-five parts of dried polyethylene (90 percent terephthalate, 10 percent isophthalate) having a melting point of about 211 C. was blended in a Banbury mixer with 25 parts of a dried copolyamide (inherent viscosity=0.65) derived from 80 mole percent of e-aminocaproic acid (lactam) and 20 mole percent of 1,4-cyclohexylene dimethylenediamonium isophthalate. The resulting blend was extruded into rod, pelletized, and then melt spun into 50-filament yarn having a tenacity of 3.31 g./den. and an elongation of 40 percent. Knit tubes from this yarn showed excellent affinity for premetallized dyes, whereas yarn from the unmodified polyester showed little or no tendency to take up these dyes. Dyed samples of the modified polyester yarn showed excellent resistance to trichloroethylene at F. and showed no fading after 40 hours exposure to ultraviolet light in the Fade-O-Meter.

EXAMPLE 19 Nine parts of dry poly-1,4-cyclohexylenedimethylene (83 percent terephthalate, 17 percent succinate) was mechanically blended with 1 part of a dry copolyamide (inherent viscosity=0.61) derived from 20 mole percent of 1,4- cyclohexalenedimethylenediammonium isophthalate and 80 mole percent of hexamethylenediammonium adipate. The resulting blend was melt spun into SO-filament yarn which was knitted into a sock for dyeability test. Deep shades were obtained with premetallized and disperse dyes. The dyed materials showed no tendency to crock. They were light fast and there was substantially no loss of dye in sublimation or dye bleeding tests.

EXAM PLE 2 Example 19 was repeated using polypentamethylene (83 percent 4,4-sulfonyldibenzoate, 17 percent succinate) as the polyester. The resulting copolyamidemodified polyester dyed readily to deep, fast shades.

EXAMPLE 21 This example shows the deleterious effects of maintaining the polyester/copolyamide blends in the melt over prolonged periods of time.

A mixture of 9 parts of poly( ethylene terephathalate) having an inherent viscosity of 0.74 and 1 part Of a 6/66/ 610 terpolyamide derived from weight percent of e-caprolactarn, 70 weight percent of hexamethylenediammonium adipate and 15 weight percent of hexamethylenediamrnonium sebacate was prepared by mechanically blending pellets of the two polymers in a suitable vessel fitted with a stirrer. The blend was slowly heated over a 3-hour period to 200 C. at a pressure of 10-22 mm. of mercury in a current of dry, oxygenfree nitrogen in order to dry the polymers thoroughly. The temperature was raised to 270275 C. and the resulting melt was stirred continuously at this temperature for about 90 minutes. The resulting homogeneous blend was extruded from the vessel in the form of a As-inch rod and was chopped into pellets. The composition obtained in this manner was subjected to melt spinning, but could not be satisfactorily melt spun continuously. Melt spinning was accompanied by non-uniform draw-down of the filaments which resulted in numerous breaks. The small amount of yarn which was obtained was non-uniform and had no potential textile value.

It Was evident from the homogeneity and the vast change in the character of the fibers extruded from the above composition that the polyester and the copolyamide modifier under the influence of prolonged heating in the melt had reacted to form a different polymeric species. Such a reaction is undesirable in the practice of the present invention. When the invention is practiced as illustrated in the examples above, substantially no inter action between the polyester and the polyamide occurs and the fibers obtained therefrom when observed in cross section with a polarizing microscope show the presence of two discrete heterogenous phases; that is, the modifier phase dispersed in the polyester phase.

EXAMPLE 22 Example 21 was repeated except that the terpolyamide was derived from 40 parts hexamethylenediammonium adipate, and 30 parts of hexamethylenediamrnonium sebacate, and 30 parts of ecaprolacta-m. The resulting homogeneous blend had a melting point of 228-233 C. It could not be melt spun continuously into commercially acceptable yarns. The small quantities of fibers which were obtained were non-uniform, highly discolored and had poor physical properties. In addition, these fi ers could not be dyed satisfactorily, since they tended to dye off-shade. Cross sections of the fibers when examined under the polarizing microcope appeared to be homogeneous.

The utility of our invention speaks for itself inasmuch as there is provided a means of solving one of the most difficult and long standing problems in the manufacture of commerically acceptable polyester filaments, fibers and other products, namely, the permanent dyeing of such material with dyes such as premetallized, acid wool, disperse and other types of dyes by the dyeing procedures commonly employed in the textile industry. Not only does our invention provide a means of obtaining deep shades which are light fast and gas fast but also, particularly where premetallized dyes are employed, the resulting fibers are found to be highly resistant to the action of dry cleaning solvents such as trichlorethylene which has a pronounced tendency to bleach out colors as heretofore employed in the dyeing of polyester fibers. Our invention also provides a means of obtaining polyester fibers having improved physical properties such as excellent soil resistance, greater moisture regain, less tendency to develop static charges and other properties which render such fibers readily processable on textile machinery.

Examples 3, 5, 6, 21 and 22 have been included in this specification as exemplary of What might be inferred from the prior art and what should be avoided in practicing the invention.

The present invention has been described in considerable detail with particular reference to certain preferred embodiments thereof; however, it will be understood that certain variations and modifications can be affected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A dyeable shaped article of a composition consisting essentially of a chemically heterogeneous blend of (A) a linear condensation polyester having an inherent viscosity of at least about 0.4 and a melting point in the range of about to about 350 C. and (B) a linear condensation polyamide wherein the carbonamide groups are separated by at least two carbon atoms and are an integral part of the main polymer chain, said polyamide being selected from the group consisting of (1) copolyamides present in amounts of from 1 to about 20 percent by weight of said composition and comprising from 2 to 4 diiferent repeating units of:

(a) NHRCO (b) -OC(R)CONHR"-NH and (c) Combinations of (a) and (b) wherein each of R, R and R" is a divalent hydrocarbon radical containing up to 12 carbon atoms, said copolyamide having a melting point in the range of from about 140 to about 260 C. and (2) homopolyamides present in amounts of from 1 to about 20 percent by weight of said composition and comprising repeating units selected from the group consisting of:

wherein each of R, R, and R" is as defined above, said homopolyamide having a melting point in the range of from about to about 320 C.; said polyamide having an inherent viscosity of at least about 0.6, and having a melt viscosity substantially equal to or less than that of said polyester.

2. The article of claim 1 in which R contains 3 to 11 carbon atoms, R contains 1 to 10 carbon atoms and R" contains 2 to 12 carbon atoms.

3. The article of claim 1 in which the polyamide is a copolyamide that consists essentially of the following repeating units:

4. The article of claim 1 in which the polyamide is a copolyamide that consists essentially of the following repeating units:

copolyamide that consists essentially of the following repeating units:

7. The article of claim 1 in which the polyamide is poly(epsilon-caprolactam).

8. The article of claim 1 in which the polyamide is poly(hexamethylene adipamide).

9. The article of claim 1 in which the polyamide is poly hexamethylene seb acamide) 10. The article of claim 1 in which the polyamide is poly(m-xylylene sebacamide).

11. The article of claim 1 in which the polyester is poly 1,4-cyclohexylenedimethylene terephthalate).

12. The article of claim 1 in which the polyester is poly(ethylene terephthalate).

13. The article of claim 1 in which the polyester is poly pentamethylene 4,4-sulfonyldibenzoate 14. The article of claim 1 in which the polyester is poly(ethylene terephthalate 97 percent, sulfoisophthalate 3 percent).

15. The article of claim 1 in which the polyester is poly(ethy1ene terephthalate 90 percent, isophthalate 10 35 percent).

16. The article of claim 1 in which the polyester is poly(1,4-cyclohexylenedimethylene terephthalate 83 percent, succinate 17 percent).

17. The article of claim 1 in which the polyester is poly(pentamethylene 4,4-sulfonyldibenzoate 83 percent, succinate 17 percent).

18. The article of claim 1 in which the polyamide is a copolyamide and is present in an amount within the range of 5 to 20 percent of the total composition, said copolyamide having an inherent viscosity within the range of 0.8 to 1.5, and said article characterized in that it may be dyed to deep shades using dyes selected from the group consisting of premetallized dyes, acid wool dyes and disperse dyes, said dyed article having a light-fastness of greater than 20 hours exposure under intensified, simulated sunlight.

19. The article of claim 1 in which the polyamide is a homopolyamide present in an amount within the range of to 30 percent of the total composition, having an inherent viscosity in the range of 0.6 to 1.5 and insoluble in ethanol water mixtures.

20. The invention of claim 1 wherein the shaped article is a fiber. 60

21. The invention of claim 11 wherein the shaped article is a fiber.

22. The invention of claim 12 wherein the shaped article is a fiber.

23. A process for preparing a synthetic fiber having improved dyeability and having a composition consisting essentially of a chemically heterogeneous blend of (A) a linear fiber-forming condensation polyester having an inherent viscosity of at least about 0.4 and a melting point in the range of about 150 to about 350 C. and 70 (B) a linear condensation polyamide wherein the carbonamide groups are separated by at least two carbon atoms and are an integral part of the main polymer chain, said polyamide being selected from the group consisting of (l) copolyamides present in amounts of from 1 to about 20 percent by weight of said composition and comprising from 2 to 4 different repeating units of:

(a) NHRCO (b) OCR'CONHR"NH-, and (c) Combinations of (a) and (b) wherein each of R, R and R" is a divalent hydrocarbon radical containing up to 12 carbon atoms, said copolyamide having a melting point in the range of from about to about 260 C. and (2) homopolyamides present in amounts of from 1 to about 20 percent by weight of said composition and comprising repeating units selected from the group consisting of:

wherein each or R, R and R" is as defined above, said homopolyamide having a melting point in the range of from about 160 to about 320 C., said polyamide having an inherent viscosity of at least about 0.6 and having a melt viscosity substantially equal to or less than that of said polyester, said process comprising the steps of intimately blending essentially completely dried, molten components (A) and (B), and melt spinning fibers from the molten blend of said components prior to chemical interaction between said components which may be deleterious to melt spinning of the fibers into multifilament yarns.

24. A dyeable shaped article of a composition consisting essentially of a substantially unreacted blend of (A) a linear condensation polyester having an inherent viscosity of at least about 0.4 and. a melting point in the range of about to about 350 C. and (B) a linear condensation polyamide wherein the carbonamide groups are separated by at least two carbon atoms and are an integral part of the main polymer chain, said polyamide being selected from the group consisting (1) copolyamides present in amount of from 1 to about 20 percent by weight of said composition and comprising from 2 to 4 different repeating units of:

(a) NHRCO, (b) OCR'CONHR"NH, and (c) combinations of (a) and (b) wherein each R, R and R" is as defined above, said homopolyamide having a melting point in the range of about to about 320 C., said polyamide having an inherent viscosity of at least about 0.6 and having a melt viscosity substantially equal to or less than that of said polyester.

References Cited UNITED STATES PATENTS 5/1968 Breen 260-857 12/1961 Zoet'brood 260-75 MURRAY TILLMAN, Primary Examiner J. T. GOOLKASIAN, Assistant Examiner US. Cl. X.R.

PC1050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 9 ,3 Dated January 27, 1970 Inventor(s) Harry W. Coover. Jr. and Frederick B. Jovner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[- Column 2, line 67, "sbject" should read ---object---. l

Column 3, formula (2)should read -OC-(R')-CO-NH-R"-NH- Column 6, line 15, "have"-should read ---having--. Column 13, line 26, "ammonium" should read ---dia.mmonium--. Column 13, line 74, 'C.I. Blue 11" should read ---C.I. Disperse Blue ll.---

SIGNED AND SEALED (SEAL) Arrest:

I WILLIAM E- SGHUYIAER, IR. Edward -52;: Commissioner of Patents Attesting