US3671379A - Composite polyester textile fibers - Google Patents

Abstract

HELICALLY CRIMPABLE AND CRIMPED BICOMPONENT FILAMENTS COMPRISING A LATERALLY ECCENTRIC ASSEMBLY OF AT LEAST TWO A PARTLY CRYSTALLINE POLYESTER IN WHICH THE CHEMICAL REPEATUNITS OF ITS CRYSTALLINE REGION ARE IN A NON-EXTENDED STABLE CONFORMATION THAT DOES NOT EXCEED NINETY PERCENT OF THE LENGTH OF THE CONFORMATION OF ITS FULLY EXTENDED CHEMICAL REPEAT-UNITS AND IS GENERALLY ON THE INSIDE OF THE CRIMP HELICES FORMED WHEN THE ASSEMBLY CRIMPS, WHILE AT LEAST ONE OTHER POLYESTER COMPONENT IS PARTLY CRYSTALLINE AND THE CHEMICAL REPEAT-UNITS OF THE CRYSTALLINE REGION MORE CLOSELY APPROACH THE LENGTH OF THE CONFORMATION OF ITS FULLY EXTENDED CHEMICAL REPEAT-UNITS. YARNS, FABRICS, AND THE LIKE PRODUCED FROM THESE FILAMENTS HAVE A WIDE RANGE OF END USES.

Description

June 20, 1972 E. F. EVANS ETAL COMPOSITE POLYESTER TEXTILE FIBERS Filed March 9, 1971 F G 5 qll illl' INVENTORS EVAN FRANKLIN EVANS NORWIN CALEY PIERCE ATTORNEY United States Patent US. Cl. 161-173 18 Claims ABSTRACT OF THE DISCLOSURE Helically crimpable and crimped bicomponent filaments comprising a laterally eccentric assembly of at least two synthetic polyesters. At least one of the components is a partly crystalline polyester in which the chemical repeatunits of its crystalline region are in a non-extended stable conformation that does not exceed ninety percent of the length of the conformation of its fully extended chemical repeat-units and is generally on the inside of the crimp helices formed when the assembly crimps, while at least one other polyester component is partly crystalline and the chemical repeat-units of the crystalline region more closely approach the length of the conformation of its fully extended chemical repeat-units. Yarns, fabrics, and the like produced from these filaments have a wide range of end uses.

CROSS REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of our copending application Ser. No. 747,420, filed July 10, 1968, now abandoned, which in turn is a continuation-in-part of our copending application Ser. No. 611,314, filed J an. 24, 1967, now abandoned, which in turn is a continuation-in-part of our application Ser. No. 462,992, filed June 10, 1965, now abandoned, which in turn is a continuation-in-part of our application Ser. No. 384,831, filed July 24, 1964, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to self-crimpable and crimped composite synthetic filaments and, more specifically, to such composite filaments which have the potential for development of a broad range of desirable crimp properties.

It is frequently desirable in applications of synthetic fibers to attain a degree of stretchability not inherently characteristic of fabrics made therefrom. In the past such stretchability has usually been attained by incorporation of an elastomer, such as natural rubber or a synthetic rubber, into the fabric structure. This alters tactility markedly and increases the weight of the fabric. Fabrication of woven, light-weight. fabric with a useful degree of stretch has heretofore been impractically expensive. It is true that synthetic fiber yarns which have artificially induced crimpiness have some stretchability, but this has invariably been either of minor degree and of low re covery power and rate or so limited by twist-liveliness as to have no practical utility in light-weight flat fabrics. Such yarns may have, for example, either mechanically induced crimpiness, heat-set twist or spontaneous crimpability based on a bicomponent structure of the type more fully described below. Crimping confers bulkiness Patented June 20, 1972 "ice a more synthetic components which components differ in their ability to shrink, in an intimately adhering, coextensive relationship that is eccentric over the cross-section of the filament are known in the art. In US. Pat. No. 2,931,- 091, for example, it is shown that two condensation polymer components which differ in shrinkability can be cospun, in either eccentric sheath-core or side-by-side relationship. Such a filament crimps helically when subjected to shrinking conditions in an essentially tensionless state, the number of crimps-per-inch being directly related to difference in shrinkage between components. Such crimp is useful in providing bulk and resilience in fabrics, stuffing materials, etc. However, bicomponent filaments have been severely limited in their ability to crimp against a restraining load such as that encountered in woven fabrics and lose very substantially in their ability to crimp when the fiber has been annealed to low shrinkage.

SUMMARY OF THE INVENTION The present invention provides helically crimpable and crimped filaments comprising a laterally eccentric assembly of at least two synthetic polyesters, the first of said two polyesters being partly crystalline in which the chemical repeat-units of its crystalline region are in a non-extended stable conformation that does not exceed percent of the length of the conformation of its fully extended chemical repeat-units and which assumes a position on the inside of the crimp helices formed when the assembly crimps, the second of said two polyesters being partly crystalline in which the chemical repeat-units of the crystalline region are in a conformation more closely approaching the length of the conformation of its fully extended chemical repeat-units than the first defined polyester.

The composite filament defined in the preceding paragraph provides a synthetic multi-component filament which is capable of developing a high degree of helical crimp against the restraint imposed by high-thread-count woven structures, which crimp potential is unusually well retained despite application of elongating stress and high temperature. It further provides a synthetic composite filament which surprisingly increases, rather than decreases, in crimp potential when annealed. It still further provides aesthetically pleasing fabric structures comprising such filaments which range from light-weight, fiat fabrics with good stretch, stretch recovery and stretch power to bulky, wool-like staple fibers and low-stretch novelty fabrics which may exhibit crepe. It also provides a route to flat, continuous-filament or staple-containing fabrics of durable stretchiness without the problems associated with twist-lively yarns.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic, transparent view of a spinneret plate of the post-coalescence type;

FIG. 2 is a side view of cooperating channels in a spinneret assembly;

FIG. 3 is an enlarged view showing the face plate opening of channels of the type of FIG. 2; and

FIGS. 4, 5 and 6 are cross-sections of some of the type filaments that can be produced in this invention.

3 DESCRIPTION OF THE INVENTION The critical limitation in the composite filaments of this invention is the character of the two polyesters that must be present, namely, that the chemical repeat-units in the crystalline regions of one polyester must be in a nonextended stable conformation that is 90% or less of the length of the conformation of its fully extended chemical repeat-units, and the chemical repeat-units in the crystalline region of the other polyester must be in a conformation more closely approaching its fully extended conformation. These crystallinity requirements are met because they are a physical or structural characteristic of the special polyester that must be present. If should be understood that the term partly crystalline as used in defining the filaments of this invention serves to eliminate from the scope of the invention the limiting situation of complete crystallinity wherein the potential for shrinkage would disappear. Hence, the amount of crystallinity, defined by the term partly crystalline, has a minimum level of only the presence of some crystallinity (i.e., that which is first detectible by X-ray diffraction means) and a maximum level of any amount short of complete crystallinity.

Although this invention is directed to composite filaments which contain at least two synthetic polyester component filaments as described above, it is preferred that the composite filaments are bicomponent filaments in which the two components are the aforedescribed polyesters. Since it is these two components that are the critical elements in the filaments of this invention, such filaments will be discussed hereinafter primarily in terms of bicomponent filaments.

Before entering into a detailed discussion of the manner in which the two polyester components behave to achieve the crimpable or crimped bicomponent filaments comprising them, it should be pointed out that the term laterally eccentric as used herein is used in its commonly accepted connotation in the field of bicomponent filaments. Thus, the two polyester components are spun together in such a manner that each component forms, over the crosssection of the single bicomponent filament, a distinct zone which extends throughout the entire length of the filament in eccentric fashion, whereby only one, or part of, or all of the components take part in forming the surface of the single bicomponent filament. Thus, in one embodiment, the two components will be present in substantially constant ratio in the filament cross-section; while in another embodiment each component may vary in its crosssectional ratio. The components may be in an eccentric sheath-core relationship, but, preferably, they will be present in the bicomponent filaments in a side-by-side relationship, such as is described in US. Pat. 2,931,091.

Thus, it is seen that the spontaneous crimping of the bicomponent filament is the result of differential changes in the length of the two polyester components which arise from a difference in the degree of their respective retraction after draw or their shrinkage after subsequent heat treatment or both.

Although the reason for the differential changes in length is not fully established and the invention should not be limited by a theoretical consideration, the discussion which follows may assist in understanding the invention. The differential in the changes in length of the two critical polyester components arises from the difference in the crystalline structure of the two polyesters, and it is believed that if an oriented polymer crystallizes in an extended conformation (as do most polyesters), i.e., one in which the conformation of the chemical repeat-units in its crystalline region closely approaches that of its fully extended chemical repeat-units, as the polymer crystallizes in the oriented state, repeat-units are transferred from a noncrystalline region of the polymer to a crystalline region and the orientation of units remaining in the noncrystalline region becomes less. Potential ability to shrink is greater for fibers with more highly oriented noncrystalline regions than for fibers with lower orientation in the noncrystalline regions. Thus, the partially crystalline extended-type polymer loses potential ability to shrink as it continues to crystallize. If, on the other hand, the oriented polymer is one whose chemical repeat-units crystallize in a nonextended conformation, i.e., one in which the length of the chemical repeat-units of its crystalline region is shorter than that of its fully extended chemical repeat-units, then, during crystallization in the oriented state, as repeat-units are transferred from a noncrystalline region of the polymer to a crystalline region, the orientation of units remaining in the noncrystalline region becomes greater. Thus, further crystallization of such a nonextended type polymer results in a higher tendency to shrink upon relaxation.

From the foregoing discussion, it is seen that if a bicomponent filament is composed of the extended-type polymer and the nonextended type polymer in a laterally eccentric relationship, the difference in the conformation of their chemical repeat-units in the crystalline regions will result in the crimpable and crimped filaments of this invention. Maintenance of this differential shrinkage and retraction potential between the components of the filament requires geometrical stability in the crystalline chemi cal repeat-units of the high-shrinkage component, except for those rearrangements necessary to shrinkage. Otherwise, the potential energy required for crimping may be dissipated by molecular rearrangements to a more stable crystalline state (of lower shrinkage). In other words, when under stress, a partial disruption of the conformation of the crystalline region may occur which causes a rearrangement to a conformation in which the chemical repeat-units are in a more extended conformation. Thus, the term stable as used herein is meant that the nonextended chemical repeat-units of the crystalline region do not undergo an irreversible loss of dimensional recovery potential, i.e., they revert back to substantially their original nonextended conformation upon the release of the stress and with the application of heat.

It is also seen from the foregoing discussion that the unusual properties of the bicomponent filament of this invention will be fully realized if the overall orientation of the high-shrinkage component (i.e., the nonextended component) in its uncrimped amorphous state is greater than its orientation in its partially crystalline conformation. Orientation of the synthetic fiber may be accomplished in either or both of two ways: (1) by withdrawing the solidifying filament from the spinneret at a rate higher than its extrusion velocity, and (2) mechanical stretching of the solidified filament.

It is sometimes desirable, particularly when maximum crimp development is desired, that the high-shrinkage component be more highly oriented. It is obvious that the mechanical stretching step imparts the same draw ratio to both components and is therefore not highly effective in establishing an advantage in orientation for the high-shrinkage component. To insure that the advantage in orientation is accomplished, it is sometimes desirable that the high-shrinkage component be more highly oriented during spinning. This can be done by using ahigher molecular weight (higher melt-viscosity) polymer for the high-shrinkage component. This same effect can be realized, however, by suitable use of melt-viscosity modifiers in one component, and such process variations are within the scope of this invention.

The use of a polyester which crystallizes in a nonextended conformation as the high-shrinkage component of the bicomponent filament provides substantial advantages over a combination of polymeric components which shrink unequally due to another difference such as in molecular weight, tensile recovery, glass transition temperature, etc. While the composite fibers known in the art possess differing degrees of potential shrinkability among components as a result of variations in response of the components to manufacturing conditions employed, in no instance has such difference been found completely retained or, more strikingly, enhanced by stress and/or high temperature, as is the case with the composite filaments of this invention. A particularly advantageous property of the bicomponent filaments of this invention is their ability to crimp against a restraining load imposed by woven fabrics made therefrom. Stretchability and recovery from stretch can be adjusted over a wide range by choice of process variables as will be shown below.

Accordingly, and subject to the critical crystalline conformation requirements, it is apparent that the composite bicomponent filaments of the present invention can be composed of any number of any of the polyesters including polyester copolymers, that can be readily melt spun. It is especially preferred that the more extended polyester have the chemical repeat-units in its crystalline region in a conformation that is 95% or more of the length of the conformation of its fully extended chemical repeat-units. Suitable polymers can be found for instance, among the fiber-forming polyesters which are described in US. Pats. Nos. 2,071,250, 3,018,272, and 2,465,319, and various articles such as Wilfong, Polymer Science, 54, 385-410 (1960). Non-extended polyesters that are preferred (i.e., those that exhibit the critical shortened chemical repeat-units in their crystalline regions) are poly(trimethylene terephthalate), polytetramethylene terephthalate), poly(trimethylene dinaphthalate) (trimethylene dinaphthalate throughout the application means trimethylene 2,6-dinaphthalate), poly(trimethylene bibenzoate), copolymers of the above with ethylene sodium sulfoisophthalate, and selected polyester ethers. Poly(ethylene terephthalate), poly(cyclohexyl 1,4-dimethylene terephthalate), copolymers thereof, and copolymers of ethylene terephthalate and the sodium salt of ethylene sulfoisophthalate are the preferred polyesters for the other (more extended) component, but other polyesters such as the corresponding copolymers of ethylene terephthalate containing sebacic acid, or isophthalic acid as well as those containing recurring units derived from glycols with more than four carbon atoms in the chain can be used as well.

When ethylene sodium sulfoisophthalate is used in cm polymerized form as one component of a copolyester, it is preferably the minor component, i.e., present in amounts of less than 5 mol percent and preferably present in amounts of about 2 mol percent.

The conformation of the chemical repeat-units in the crystalline region of a number of polymers have been deduced from X-ray and model data.

Table 1 gives the extended chemical and the crystalline repeat unit distances for a number of polyesters.

TABLE 1 Repeat-distance (A) Fully extended Crystalline Percent Polymer repeat-unit chemical chemical extended Ethylene terephthalate 10. 9 10. 7 98 Trimethylene terephthalate 2 24. 4 5 18.2 75 Tetramethylene terephthalate 13. 4 11. 7 87 Trans-Cyelohexanedimethylene terephthalate 14. 7 14. 2 97 Ethylene 2, fi-dinaphthalate- 13. 4 13. l 98 Trimethylene dinaphthalate- 14. 5 11.5 79 Trlmethylene blbenzoate 16. 6 13. 3 80 1, 3-Cyclobutane dimethylene terephthalate 14. 3 13. 4 94 1, 3-Cyclobutane dimethylene bibenzoate- 18. 6 18 97 1 Repeat-distance=length of repeat-unit. 2 Two unlts.

Determinations of this nature are accomplished as follows: Measurement of the Percent extended parameter is done as follows (the order of steps A and B is immaterial):

Step A.Measurement of crystalline repeat-distance A parallel bundle of oriented and partly crystalline fibers is mounted in an X-ray beam with the fiber axis perpendicular to the beam. A flat photographic film is placed in and perpendicular to the X-ray beam at a distance of a mm. from the fiber array on the opposite side from the X-ray source. The film is suitably exposed and developed to show a fiber pattern consisting of a family or more-or-less complete hyperbolae with its axis parallel to the fiber axis, i.e., on the so-called meridian. The distance on the film along this line from the primary-beam image to each hyperbola is measured and designated e n being the ordinal number of the layer line counting away from the equator as zero. The diffraction angle u is defined as u =tane /a. The identity period (Crystalline Repeat) is then simply calculated from nh sin a where A is the wavelength of the X-rays used. The above notation follows G. L. Clark, Applied X-rays, McGraw- Hill, New York (1955), p. 401. The patterns from various polymers and particular values of e of course, differ.

Step B.-Measurement of fully extended chemical repeat-distance Step C.Calculation of percent extended The Crystalline Repeat Distance from Step A (which is in angstrom units) is divided by the length calculated from measurements in Step B. The result is multiplied by to give the percent extended.

If the result of Step C is greater than 100%, obviously the crystalline chemical repeat-unit consists of more than one chemical repeat-unit. The actual number can sometimes be estimated from geometrical considerations or from a more detailed analysis of the X-ray pattern. Since the crystal repeat must be an integral number of chemical repeats, assigning one chemical repeat therefore gives the maximum possible extension; if there are two chemical repeats, the percent extension would be halved, etc.

The art of preparing composite filaments is well developed and reference may be made to techniques already known for application to the composite filaments of this invention. A partial list of US. patents that may be referred to for this purpose includes Breen, 2,987,797; Radow et al., 3,039,174; Breen, 3,038,236; Taylor, 3,038,- 237; Breen, 2,931,091; and Zimmerman, 3,038,235. In addition, the various spinnerets described in those references as well as the manner of using them may be used in this invention. Others can, of course, be employed.

Referring now to FIGS. 1, 2 and 3, two polyester melts are separately metered (by means not shown) into the two rings of holes designated as 1 and 2, in FIG. 1, in spinneret 4. A sealing means (not shown) prevents mingling of the two melts at the back face 3 of spinneret 4. The two melts flow through individual channels 5 and 6 to the front face 7 of spinneret 4 where they merge into a side-by-side composite filament as they leave the spinneret assembly. The molecular weight of the polyesters used may vary widely and generally will be in the range conventionally employed in the synthetic fiber art. The filament generally is withdrawn from the spinneret at a speed that attentuates the filament, and is thereafter drawn. The conditions applied for drawing the spun composite filaments of this invention may vary in wide limits. In addition to the processes of drawing described in some of the examples given hereinafter, a hot pin may be used, or the yarn may be passed over heated rolls, as additional examples. In general, the precise amount of draw is established by use of feed and drawing rolls which are driven at the appropriate differential in speed, care being taken to assure that the yarn doesnt slip on either. Two methods for assuring positive control of speed which are appropriate for feeding to or withdrawing from a drawing zone are described in US. 3,101,990.

Also, the temperatures at which the composite filaments are drawn may vary in wide limits and depend mostly upon the properties of the polyesters forming the composite filament and of the final desired results. As is the case in the production of conventional unitary filaments, the preferred drawing temperatures for the composite filaments of this invention may vary between room temperature and slightly elevated temperatures; for example, temperatures of about 100 C. or somewhat higher, may be used. Since in the present invention combinations of at least two different polyesters are employed, the specific drawing characteristic of each material should be considered in order to obtain best results. Drawing temperatures which are lower than the glass transition temperature (Tg) of the several components may be employed where a separate plasticizing step is provided. Moreover, if desired, the drawing and subsequent heat treatment may be coupled in a continuous process to obtain the desired orientation and crystallization.

To obtain maximum crimp properties, the filaments should be crystallized by heating under conditions wherein no shrinkage can occur. In other words, the crystallization is effected under conditions of tension which at least equal the forces developed in the filaments during the treatment. Crystallization or length stabilization of the filament components can therefore be accomplished by a heat treatment, i.e., an annealing treatment, of the taut filament. Only a short period of time at the annealing temperature is needed, for example, only a fraction of a second. Extended annealing times are not deleterious, and may be advantageously employed in some instances as will be shown. In the examples given hereinafter, the term annealing indicates that the yarn was exposed to the indicated temperature for about 0.1 to 0.5 second while held at constant length unless otherwise indicated.

The filaments as produced upon annealing may be used as such and crimp may be developed in the ultimate product. Alternatively, all the crimp may be developed first, and the crimped product then used, or it may partially be developed prior to use with additional crimp being developable in fabric form. Any conventional hot relaxing step such as a relaxed scour, known in the art, may be employed to develop the characteristic helical crimp.

As will be shown hereinafter, it is desirable for certain end uses, and particularly with staple fibers, to limit the crimp to less than the maximum obtainable. This can be accomplished in a variety of ways, including heat treatment under conditions permitting some relaxation. A preferred procedure for the production of staple fibers of this invention, i.e., short filaments, for use in spun yarn designed for use in knitted fabrics is to permit the drawn filaments to relax at an elevated temperature, e.g., 130- 150 C., to develop a somewhat higher level of crimp than desired and then stretch the filaments slightly at room temperature followed by heating in the stretched state at a temperature appreciably higher than the temperature at which the crimp was developed, the degree of stretching being adjusted to give the desired level of crimp in the final product.

The temperature applied in either taut or relaxed treatments should generally be higher than the apparent minimum crystallization temperature of the higher shrinkage component. The apparent minimum crystallization temperature is defined as the lowest temperature at which the fiber may be heated to produce a substantial degree of crystallinity in its structure and is well known or can easily be determined for each polymer. A convenient method for determining the apparent minimum crystallization temperature (Ti) is described, e.g., in

US. 2,578,899. Preferably, however, the apparent minimum crystallization temperature is determined by X-ray diffraction measurements on samples of filaments which have been drawn in cool water to prevent crystallization and which have been subjected to taut heat treatment at progressively increasing temperatures. X-ray diffraction patterns are suitably made using a Warhus camera, such as described by Statton, W. 0., Polymer Reviews, vol. 6, Chapter 6, Interscience Publishers, New York, NY. (March 1964). The degree of crystallinity may be judged by direct examination of the diifraction pattern or from radial densitometer traces along the equator of the X-ray diagram. Such a trace will show distinct peaks for fibers having a well-developed crystalline structure whereas with an amorphous structure or with very low degrees of crystallinity the peaks cannot be resolved. The apparent minimum crystallization temperature by this method is the minimum temperature of heat treatment at which a definite crystalline structure is detectable from direct examination of the X-ray diagram or at which distinct peaks are observable in the densitometer trace.

The important characteristic of those polyesters having the crystalline repeat distance or less of the fully extended repeat distance that largely contributes the enhanced and highly unusual properties of the composite filaments of this invention is the effect on crimpability of heating at constant length. For the composite filaments known heretofore, heat treatment at constant length tended to destroy, or at least lessen, crimping characteristics. For the composite filaments of this invention, such heat treatment enhances the crimping characteristic, since the shrinkage differential of the two components will ordinarily be greater after the taut heat treatment than before.

It might sometimes be desirable to spin a bundle of filaments which comprises composite filaments containing the polyester components in various ratios through one and the same spinneret; for example, a bundle of two-component composite filaments which comprises filaments consisting of 20% by weight of the higher shrinkage component and 80% by Weight of the other, a 30%/70% ratio, a 40%/60% ratio and a 50%/50% ratio, respectively. Such filament bundles containing composite filaments with various ratios of components can very conveniently be produced by utilizing the spinneret which is shown in FIGS. 6 and 7 of the US. Patent to Breen 3,118,011. As a generality and without regard to the type composite filament being produced, the nonextended component usually comprises 20 to 80% of the composite and the other components comprise the remainder. The denier of the resulting product will be that usually produced in this general art, and is not of significance to the invention.

The invention will be described further in conjunction with a series of examples. In the examples, except as otherwise indicated, the terms employed in evaluating polymers and fibers have the following meanings:

Relative viscosity refers to the ratio of the viscosity of a solution of which ml. contains 10 grams of polymer in a solvent of 10 parts of phenol and 7 parts of 2,4,6-trichlorophenol (by Weight) to the viscosity of the solvent itself, both measured at 25 C., using a capillary viscometer and expressed in the same units.

Intrinsic viscosity is defined as the limit of the fraction ln (r) as concentration 0 approaches zero, where r is the relative viscosity as defined above, except that the relative viscosity is measured at several conventrations to facilitate extrapolation to zero concentration, and the solvent employed in this measurement is a mixture of three parts of methylene chloride and one part of trifiuoroacetic acid (by weight). A more detailed discussion of methods of measuring relative and intrinsic viscosities is given in Preparative Methods of Polymer Chemistry, Sorenson & Campbell, Interscience, 1961.

Skein shrinkage is determined by the following procedure:

(1) From the known denier of the yarn, calculate the number of turns of a skein reel required to achieve a skein with a denier of 1500 (167 tex.) (the circumference of the reel may be any convenient length), using the formula where T designates turns on the skein reel and d is denier of the yarn; round oflE to the nearest integral number of turns. Prepare and label a skein from each yarn to be tested. It will be obvious that such a skein must be considered as 3000 denier (334 tex.) when loaded as a loop.

(2) Hang the skein and apply a 300-gm. weight at the bottom of the loop. Exercise gently by raising and lowering four times. Wait 15 seconds and measure initial length of the skein (L (3) Replace the 300-gm. weight with a 4.5-gm. weight and immerse the skein in boiling water for 15 minutes. Remove from bath.

(4) Remove the load and allow the skein to hang without load for 1 hour or more to dry. Replace the 4.5- gm. load, exercise by pulling down, and measure crimped length (L (5) Reapply the 300-gm. load, exercise and measure extended skein length as in 2 above (L (6) Calculate skein shrinkage by the formula L10 Crimp development-Calculate from data obtained in the skin shrinkage procedure by the formula Crimp elongationDetermine by the procedure employed in skein shrinkage with the addition of one more step: after measurement of L (Step 5), the 300-gm. load is replaced by the 4.5-gm. load and a second measurement of recovered length under the smaller load is made as in Step 4 of that procedure (L Crimp Elongation is calculated by the formula EXAMPLE I This example illustrates batch preparation of poly(trimethylene terephthalate), coded herein PPT polymer.

Catalyst for this preparation is prepared as follows: Sodium (2.5 gms.) is dissolved in 300 ml. of n-butanol. Tetrabutyl titanate (37 gms.) is then added and the mixture diluted to '500 ml. with n-butanol.

Dimethyl terephthalate (5.45 kg.) and trimetlr'ylene glycol (4.54 kg.) are heated for 100 minutes at 225 C. in the presence of 99 cc. of the stock catalyst solution described above. During this time, 1.8 kg. of methanol are removed. The resulting low molecular weight material, to which a small amount of titanium dioxide has been added as a delusterant, is heated further, with stirring, for 6 hours at 250 C. under an absolute pressure of 0.4 mm. of mercury during which time the glycol evolved during further condensation is removed. The resulting polymer has an intrinsic viscosity of 0.71.

Poly(trimethylene terephthalate) can be made in a variety of ways, many of which are well-known in the art. Since the process detail employed in its manufacture is not critical to the utility of PPT polymer in practice of this invention, polymer made by several processes has been employed herein indiscriminately.

10 EXAMPLE n This example illustrates a means of enhancing the molecular weight, as evidenced by an increase in intrinsic viscosity, of a polymer such as that prepared in Example I.

'PPT polymer of less than 1.0 intrinsic viscosity is out twice to pass through a V8 inch mesh screen, dried 6 hours at C. and placed in a vessel through which inert gas is passed. The inert gas and vessel are heated to 180 for two hours, then to 200 C. for an additional 12 hours. The polymer and apparatus are then cooled and the polymer removed. The intrinsic viscosity of the finished polymer is 1.29. A second batch of this polymer is prepared and found to have an intrinsic viscosity of 1.36.

Polyethylene terephthalate (PET polymer) may be prepared by any of a variety of procedures known in the art, such as one of the methods taught by Whinfield and Dickson in U.S. Pat. 2,465,319, or one of the methods of Grifiing and Remington described in U.S. Pat. 3,018,272. While each of these methods may have merit over another in some respect such as in the production of a whiter polymer or in improved space-time yield, these diiferences are not critical to the purpose of this invention. PET polymer employed in these examples has accordingly been derived from several procedures as dictated only by convenience and availability.

EXAMPLE III Examples and IV illustrates a preferred process for preparation of a bicomponent fiber of this invention.

The blended PPT polymers of Example 11, and a PET polymer of 18 relative viscosity are cospun at 280 C. from a 34-hole spinneret similar to that described in FIG. 14 of U.S. Pat. 3,117,362; this is a pre-coalescence spinneret, that is, one in which the two melts are brought together just behind each extrusion capillary. The filaments are withdrawn from the spinneret at 468 y.p.m., drawn 470x (that is, to 470% of their original length) at 93 C., and annealed at C. The 68 denier (7:6 tex.) yarn has a skein shrinkage of 12%, crimp development of 55% and crimp elongation of 106%.

EXAMPLE IV A 34-filament bicomponent yarn is prepared from a PPT polymer of 1.2 intrinsic viscosity and a PET polymer of 20 RV in a ratio of 40/60, by cospinning at 280 C. from the post-coalescent spinneret shown in the drawing. The filaments are withdrawn from the spinneret and wound up at 820 yards per minute. The spun yarn is drawn 3.982X at 107 C. and annealed at 150 C. Properties of the yarn are: denier 63, tenacity 3.2 g.p.d., elongation to break 11%, skein shrinkage 1 6%, crimp development 52%, crimp elongation 95%. Contrary to the procedure generally used herein, the latter three measurements are made at 1.4 mg./den. restraint rather than the standard 1.5 mg./den. restraint. (See procedures for these measurements above in which a 4-2 gm. weight would be used wherever a 4.5 gm. weight is specified.) Another sample of the spun yarn drawn 3.982X at 107 C. is annealed at C. The yarn has a skein shrinkage of 13%, a crimp development of 58%, and a crimp elongation of 106% (the last three measurements also being made at 1:4 mg./den. restraint).

EXAMPLE V This example illustrates suitability of a copolymer as the outer component of the composite fiber of this invention.

A PPT polymer of 1.47 intrinsic viscosity and a co polymer of 98% PET and 2% ethylene sodium sulfoisophthalate of 15.5 relative viscosity, prepared by the general procedure of U.S. Pat. 3,018,272 are employed in this example.

1 1 The two polymers are melted and simultaneously extruded at"288 C. as in Example III. The 34 composite filaments are withdrawn at 700 yards per minute, drawn to 365% of their original length at 94 C. in a water I 2 EXAMPLE VIII This example illustrates further the unusual response of bicomponent fibers of this invention to annealing.

PET polymer of 19 relative viscosity and PPT polymer bath substantially as described in U.S. Pat. 3,091,805 and of 1.42 intrinsic viscosity are cospun at 5 C. fmm a gg gfig i2 3 l i g fg zig i z gg 32 3: post-coalescence spinneret. The filaments are withdrawn at 700 y.p.m. The spun yarn is drawn at several draw gatlon to break skem shl:mkag 8% cnmp develop ratios and annealed, in some cases at several temperatures. ment and crimp elongatlon 103% Data are summarized in Table 3. It should be noted that EXAMPLE VI Item VIII-c is a PET polymer homofiber which has been twisted, heat-set and untwisted by a commercial means i i i fi i i g Smtablhty of a cop 01y mer as available in the art. It is clearly seenthat imposition of a A 34-filament bicomponent yarn is prepared from a Sultan addmonal-draw heat'settmg P VHL'b copolymer of PPT with 2 mol percent sodium sulfoisoi q a measurable lmprovelnent m.cnmp proper' phthalate of 1.25 intrinsic viscosity and PET polymer of fi lcnmp of Item VIH'C 1s essenuauy destroyed RV in a ratio of 40/60, by cospinning from a posty am entlca treatment coalescing spinneret at a temperature of 284 C. The TABLE 3 filaments are withdrawn at 1080 yds./min., drawn in an Skem Crimp Crimp 87 C. bath 2.37 (or 237% of their undrawn length) 20 Draw Anneal shfinkt us and annealed at 182 C. The properties of the yarn are: Item ratio temp., o. erge iit p r nt per t denier 72 (8 tex.), tenacity -1.7 g.p.d., elongation to break 17%, skein shrinkage 19%, crimp development 46% and 238 Z 3 g crimp elongation 7% VIII-a 2.11 140 4,0 11 12 EXAMPLE v11 128 3:? it it This example illustrates the suitability of alternative VHH) ags g: g polymers in the preparation of fibers of this invention. "(13 180 46 79 In Table 2, the codes employed to represent the polyvnp 2 X1 2 fig -3 g mers have the following meaning: VHLd None 18 21 PPB=poly(trimethylene bibenzoate) No lie E18 5; PCHT=poly(trans cyclohexanedimethylene terephthal- 3 08 3 13-3 if fig ate) (solid-state polymerized in accordance with Ex. 160 15: 0 50 86 N333 it? 31 32 PPN=poly(trimethylene 2,6-dinaphthalate)-using as cat- VIII" i 180 1419 61 130 alyst a mixture of Mn (OAc) and 'Ti(OBu) ma 147:2 94 PET=po1y( ethylene terephthalate) 2 l raw ratio not l rnown, approximately 3.2. PBT=PrY(te tramethY1ne terephthalate) The next three examples illustrate the unsuitability of RPT=poly(tr1methylene terephthalate) (sohd state p0 bicomponent fibers more typical of the art.

lymerrzed 1n accordance with Example II) 40 E PLE IX Exce t for the PET olymers and except as noted above, the polymers of this example are made in accordance A PET Polymer of 22 relatlve vlscoslty and an 85/15 'with the procedure employed in Example I. They are all copolymel: of REF/Polyethylene Sebacate (PET/PBS) of spun from posbcoalescence spinnerets Items and c 2l .1 relative v1s os1ty are spun from a post-coalescence are drawn dry substantially as described in US. Pat. spmneret at to 34 slde'by'slde blcomponent 3,101,990, in which process the yarn, lubricated with a ments compnslflg 40% PET/PBS and The textile finish, is passed at a uniform rate to and over a filaments are wlghdrawn at 600 yard? f F They surface heated to the temperature indicated in Table 2 to are draw]? at 90 to 4,60% of them 9 length heat the yarn to the desired drawing temperatures and then A Portion of the We 15 not annealed high e passed over a snubbing pin where drawing tension is ture. A second portion 1s annealed at 160 C. while held applied by the drawing rolls which Withdraw the yam at constant length. Table 4 summarlzes the yarn properat the appropriately higher speed to produce the desired fies obtamed' degree of draw. Item b is drawn by the process of T E 4 Example V. Items d and e are drawn in a jet in which Annealing temperature steam is introduced at a rate sufficient to open the bundle by turbulence and, thereby, heats each filament uniformly Property None 160 to drawing temperature. As is indicated in the data, some of the fibers are annealed at more than one temperature, gfgfgfiifiigggj'figfggf ijjjjjjj 67 67 illustrating the improved crimp development obtained at Crimp devemllmentr Percent higher temperatures of annealing. Cum) elongatwn percent 8 4 TABLE 2 Polymeric components, Skein Crimp Crimp viscosity Spin Draw Anneal shn'nkdevelopelonga- Polymer temp., Draw temp., temp, Den./ Tenacity] age, ment, tion, Item Inner Outer ratio 0. ratio 0. C. fils. elongatlon percent percent percent VII-a PPB (.88) PCHT (.67) 50/50 292 3.45 107 1 6 3 gm 1. 3/10 2 24. 40 VII-b PPN (.67) PET (1s) 1 50/50 268 3.28 92 99% 2. 1% g 32 99/34 2.4/17 5 22 30 a: a 64;: 2s 12 a 22 VII-e PBT (1.1) PET (20) 1 40/60 278 4. 216 110 150 52/34 4: 6/17 13 20 36 112 $53 222: 2212 1 s VII-d PPB (.88) PET (is) 1 50/50 282 4. 60 100 73/34 2.0/9 3 15 21 VII-e PPT 1.34) PCH'I .67) 50/50 302 3.57 100 180 89/34 1.6/8 2 27 45 1 Relative viscosity; all others intrinsic viscosity.

N orE.-Items a, b, d and e spun at 690 y.p.m.; item 0 spun at 640 y.p.m.

13 It is seen that the crimp properties are not outstanding in this fiber in the absence of annealing, and essentially all tendency to crimp is lost by annealing to reduce the high shrinkage, at a temperature which leads to enhanced crimp characteristics in the fiber of this invention.

EXAMPLE X TABLE 5 Skein Crimp 1 Crimp 1 shn'nkdeveloponga- Draw Anneal ag ment, tion, Item ratio temp., 0. percent percent percent None 12. 6 1. 2 1. 4 120 8. 3 0. 7 0. 5 X-a 4. 08 140 5. 8 1. 3 0. 9 160 3. 5 0. 5 0. 5 180 3. 0. 9 0. X- 3. 52 None 11. 6 1.0 1. 2 180 1. 7 0. 7 0.7 X-c 3. 08 None 12. 2 1.0 1. 2 180 1. 7 1.0 1.1

1 Ditferences indicated in these actual data are insignificant.

It is clearly seen that essentially no crimp is developed by the fiber of this example under the standard conditions for measurement of crimp development.

EXAMPLE XI In another evaluation of some of the yarns of Example X at zero load (vs. the standard 4.5 gm. load employed in all other evaluations), it is seen that a moderate level of crimp is achieved (Table 6). It is apparent that because of its inability to develop crimp under the nominal 1.5 mg./den. (4.5 gms./3'000 den.) loading employed in the routine test, the fibers of this example will have no utility for preparation of bulky or elastic woven fabrics. Such a level of restraint, or more, is imposed by the fabric structure. Such bicomponent fibers may confer useful bulk and slight stretch in knits wherein restraint is less.

TABLE 6 zero load crimp Skein Shrink- Develop- Elonga- Draw Anneal age, ment, tion, Item ratio Temp. 0. percent percent percent Xa 4. 08 None 10. 3 15. 6 l0. 7 180 3. 0 13.7 8. 5 Xc 3. 08 {None 12. 9 6.5 5. 8 180 5. 5 18. 6 12. 5

In one experiment, a PPT polymer and a PET polymer are cospun in a pre-coalescence spinneret similar to that employed in Example III, except that a doughnut-shaped meter plate is inserted above the ring of conduits feeding PET polymer to the point of coalescence. The meter plate is carefully aligned so that one hole in the meter plate is centered over each of the 34 PET-melt conduits. As is indicated in Table 8, the meter-plate holes vary in diameter so that the rate of flow of the PET melt toward the coalescence point varies Widely. No change is made in the rate of pumping the melts to the spinneret, so that the overall denier and the denier-per-filament remain substantially constant, only the ratio of the two polymers in the individual filaments being variable. (PPT/PET ratio in the bundle as a whole is 40/60.) Spinning conditions and yarn properties are given in Table 8A. Examination of a cross section photomicrograph shows a polymer distribution among the filaments which is substantially in agreement with that calculated from the meter plate orifices (see Table 8).

TABLE 8 Number of Calculated holes with polymer this Percent of ratio Hole diameter (inches) diameter total PET/PPT 5 mil 5 14. 7 17/83 6 5 14. 7 25/75 6 17. 6 34/66 6 17.6 44/56 6 17. 6 56/44 6 17. 5 69/31 In a second experiment, the run is repeated using the same spinneret except that the meter plate is omitted. Spinning conditions and yarns properties for this experiment are also given in Table 8A.

Crimp development, percent The yarns of Table 8A and a commercial PET yarn of the same count which has been twisted, heat-set and untwisted are each doubled and knitted into a 4 /z"-diameter tubing on a circular knitting machine. The fabrics are scoured in boiling water, dried and evaluated (results given in Table 8B) as follows:

Bulk: A single thickness of the fabric is laid on a base surface of precise flatness and a glass disc, having a weight of 3 gms./cm. and precisely parallel faces, is laid on the fabric. Exact measurements of the height of the upper face of the disc from the base surface are compared with the height of the upper face of the disc when laid directly on the base surface. The volume of fabric beneath the glass disc is then determined by a simple calculation and compared with the weight of the same fabric area. Bulk is expressed in terms of cubic centimeters per gram.

Stretch and recovery: Values in Table 8B other than bulk are read from an Instron chart prepared as follows: The knit tubing denier is determined. The cross-head of an Instron is set at 2" separation and the fabric sample inserted. The instrument is run at 2" per minute per minute) separation and the stress recorded on a chart moving at 10" per minute and registering a full scale defiection on application of a stress of 0.005 g./denier. Once full-scale deflection is reached, the cross head motion is immediately reversed and returned to the original 2" sep- 1 5 aration. From the plots of stress vs. percent stretch, stretch recovery is read as recovered stretch l6 zero restraint. Microscopic examination of filaments prepared in this manner shows them to have varying distribution of the two polymers along their lengths and across their cross sections (including a few sections that are total Stretch X 100 5 composed entirely of one individual polymer).

EXAMPLE XIV Work 1s the area under the curve and is calculated as I stress (mg/denier) Xdlt (in) This example illustrates the importance of relative mo- 10 lecular weight between components to development of the where dl; is change in fabric length. desired crimp properties. In general, for maximum crimp W k 1 U1 t d development, it has been found that the higher shrinkage or recovery ca 0 a e as component must have the higher melt viscosity at the temperature of spinning. This is conveniently attained work on recovery cycle 100 15 with a higher molecular weight as indicated by relative or work on stretch cycle intrinsic viscosities. Withing the spinnable range of molecular weights for the pair of components, the greater the difference in molecular weight the better the crimp properties. TAB

LE 8B A PET polymer having a relative viscosity of 19 1s spun Y Y T tgffi gf to 24 filament yarn with each of three PPT polymers meter meter Untwist similarly prepared to have differing 1ntrms1c viscosities plate plate PET as noted. Data are summarized in Table 9. In items XIVa, Stretch percent (at mg.lden. b and c, a 40/60 ratio of polymers is used, and the fibers stressi 111 112 75 25 stretch recovery, Percent 91 90 93 are annealed at two temperatures, further illustratlng the ga k. e eifect of this variable. In another experiment, a PPT polyork recovery, percent" 41 46 50 Bulk, cmfi/g 8.7 4.5 8.7 mer of 1.79 1ntrms1c viscosity 1s cospun m a 50/50 ratio with each of the two PET polymers, having different relative viscosities as noted. The effect of molecular weight ratio on properties for both series of experiments is sum- It can be seen that the yarn with meter plate is nearly marized in Table 9.

TABLE 9 Exsrmnle XIV-a XIV-b XIV-c XIV-d XIV-e Innerrnmpni'wnt PPT PPT PPT PPT PPT Intrinsic viscosity 1.09 1. 34 1.48 1. 79 1. 79 Outer component PET PET PET PET PET Relative vlscosity 19 19 19 20 29 Cross section ratio. /60 40/60 40/60 50/50 50/50 Spin temp., c 238 288 288 295 295 Spin speed, y.p.m 544 544 544 850 850 Draw min 4.78 4. 7s 4. 78 a. 0 a. 0 Draw temp., C 95 95 92 l 92 92 93 Annealing temp., C 195 140 195 140 195 140 185 185 Denier/(tex.) 70 (7.8) 70 (7.8) 71 (7.9) 71 (7.9) 70 (7.8) 70 (7.8) 73 (8.1) 68 (7.6) Tenacity/elongation (gun/den percent 4.3/21 3.9/21 4.5/20 3.5/18 4.4/21 4.1/20 2.9/21 3.8/20 Crimp development, percent 35 9 20 58 29 64 43 Crimp elongation, percent-.. 51 10 74 24 105 38 182 81 Skein hrinkage, percent 10 15 12 17 16 20 15 18 1 Estimated value.

equal in stretch properties to that without it, and is clear- EXAMPLE XV 1y superior in bulk. Either fiber of this invention is superior to the commercial fiber in percent stretch and work, and essentially equivalent in other properties. The fiber made with the meter plate was equivalent to the commercial fiber in bulk.

EXAMPLE XIII A PPT polymer of 1.29 intrinsic viscosity and PET polymer of 18 RV are melted separately and fed in alternating increments of .043 gm. each to a standard allscreen spinning pack of the type commonly used in spinning homofiber yarns. The mixture is extruded through a spinneret of 100 holes, each 15 mils in diameter and 17 mils in depth, at 280 C. and 'wound up at 1001 yds./min. as two filament yarns. The multifilament yarn is subsequently drawn 3.21 at 100 C. and annealed at 170 C. The drawn yarn is found to possess a randomly variable crimp among the individual filaments, and the crimp is accentuated by further heat treatment under low or This example illustrates performance in fabric found typical of the fiber of this invention.

Two bicomponent fibers, XV-a and XV-b, prepared from PPT of 1.4 intrinsic viscosity and PET of 2.1 and 20 relative viscosities, respectively, and the fiber of Example III (XV-d) are processed into plain taffeta fabrics. Table 10 summarizes the data obtained. A plain-Weave fabric, XV-c, made of a PET yarn which had been twisted, heat-set and untwisted by a commercially available process is included for comparison.

It is apparent that the elongation, or stretch, and stretchpower of fabrics from the fibers of this. invention (XV-a, b, d) are much higher than those of the fabric of the prior-art fiber. This improvement in elongation was obtained without sacrifice in recovery from maximum stretch. Furthermore fabrics XV-a, b, d, all had a smooth, flat surface similar to normal taffeta or broadcloth fabrics, but the prior-art fabric had a fine surface pucker resembliug a crepe. Fabric XV-c could have been heat-set at a narrower width to give a higher finished warp count and increased fabric elongation, but the fabric surface in this case would have been so badly puckered and deformed as to be totally unacceptable for textile uses.

Knitted and woven fabrics from these yarns have good bulk but low stretch and low width losses on finishing, reflecting the low CD and the low SS, respectively. Knitted tubing prepared from these yarns by the process of Example XII have the following properties: basis weight 4.7 og./sq. yd. (159 gms./m. bulk 6.8 cm. gm., stretch 87% (5 mg./den. stress), stretch recovery 87.5%, power 1.0 mg./den. (at /2 maximum extension).

EXAMPLE XVIII This example illustrates thermal relaxing to modify the shrinkage and crimp development of the yarn to produce bulky, stretch, knitted and woven fabrics with intermediate stretch and stretch power and low width losses onfinishing. The properties reflect the intermediate level of CD and the low level of SS in this yarn.

A 34-filament bicomponent yarn is prepared from PPT of 1.2 intrinsic viscosity and PET of 22 relative viscosity by co-spinning at 302 C. from a precoalescing spinneret similar to that of Example III, using a 50/50 PPT/ PET ratio. The filaments are withdrawn from the spinneret at 535 y.p.m. (489 m./min.) then drawn to 480% of their spun length in an aqueous bath at 93 C., annealed on rolls at 130 C. and wound up. The yarn is subsequently removed from the package at 2800 y.p.m. (2560 m./min.) and fed into a jet employing air at 70 p.s.i,g. and 400 C., relaxed 11% and wound up at 2500 y.p.m. (2280 m./min.). Yarn properties are: Denier 148.4, tenacity 3.7 g.p.d., elongation 34.6%, CD 23.1%, SS 4.6%.

Knit tubing prepared as in Example XII had the following properties: basis weight 3.7 oz./yd. (126 gms./m. bulk 8.7 cm. /gm., stretch 96% (at 5 mg./ den. stress), stretch recovery 92%, power 1.4 mg./den. (at /2 maximum extension).

EXAMPLE XIX This example illustrates the utility of this yarn in the production of novel fabric textures.

A 34-filament yarn is prepared from PPT of 1.4 in trinsic viscosity and PET of 30 relative viscosity by cospinning at 297 C. from a precoalescing spinneret similar to that employed in Example III, using 50/50 PPT/ PET ratio. The filaments are withdrawn from the spinneret at 700 y.p.m. (639 m./min.), drawn to 370% of their spun length in an aqueous bath at 92 C., and annealed on rolls at 180 C. Yarn properties are: denier 70, tenacity 3,6 g.p.d., elongation 21.4%, CD SS 3.0%. This yarn is used to prepare a knitted fabric by the procedure of Example XII. When the fabric is boiled-off, severe surface distortions result, giving a novel, heavily creped appearance.

It will further be obvious that fiber deniers and crimp properties may be altered for specific end-uses, that polymer inherent (or intrinsic) viscosities may be varied (e.g., to control strength and pilling) and that other fiber and polymer modifications, such as have been taught in the art, may be employed in the practice of this invention without departing from the scope thereof.

It has been shown that this invention is useful in the production of composite filaments of high crimp development and superior crimping force with filaments find advantageous utility in many types of fabrics. It has also been shown that under appropriate processing conditions filaments with less than maximum crimp development may also be prepared, which filaments also have utility in important textile applications. Both types of filaments although distinctly different in crimp properties, offer advantages over other crimpable fibers known in the prior art in the uses for which they are intended.

Low crimp filaments made according to this invention are particularly useful in the form of staple fibers in which they possess many of the attributes of wool and can be used to produce bulky fabrics with woollike tactile aesthetics either alone or in fiber blends with wool and other man-made fibers.

The inherent differences in characteristics of and textile processes leading to staple-spun yarns, as compared to continuous filament yarns, are reflected in differing requirements for the fibers which constitute those yarns. High-crimp filament yarns make attractive, bulky and aesthetically pleasing fabrics. Staple fibers with similar crimp properties are boardy, harsh and aesthetically undesirable in typical worsted yarn and fabric constructions. As will be illustrated, lower crimp frequency (CF) and crimp development in staple fibers lead to attractive, bulky, wool-like fabrics. CF is measured as crimps per extended inch after boil-off under 1.5 mg./den. load. These crimp properties may be lowered in a variety of ways, including reduction of molecular weight (hence orientation) of the inner, non-extended, component relative to the outer component; reduction of the ratio of the inner to the outer component in the fiber cross section; changes in the disposition or configuration of the two components in the fiber; reduction of processing temperatures, draw-ratio, or time of exposure to elevated temperatures during constant-length processing of the filaments; controlled or free relaxation of the fiber at elevated temperatures during processing; and by other methods which will be apparent to those skilled in the art.

Another required property of staple fibers which is relatively unimportant in filament yarns is the initial crimp as estimated by crimp index (CI). In this specification, CI is measured in a manner identical to that for CD except that the boil-off step is eliminated. Thus, CI is a measure of the crimp available during processing of the fiber to yarn. The amount of initial crimp has a pronounced influence on the efiiciency of processing a staple fiber to a spun yarn. Excessive crimp in fiber intended for cotton-system or worsted-system processing leads to nonuniform carding and neppy, poor quality ya-rn. A preferred embodiment of this invention is a crimpable staple with CI '8, 9 CF 15, and 5 CD 15. Such fibers may be processed either as staple or as tow, the resulting yarns offering knitted and Woven fabrics of good uniformity, high bulk and wool-like tactility.

While CI is an important parameter for controlling processibility and CF plays a major role in determining ultimate aesthetics, CD is a major determinant of fabric bulk. Maximum bulk is attained in fabrics when most of the crimp is developed in yarn or fabric, as opposed to staple or tow, form. Development of bulk in a yarn or fabric, depends upon the crimpability of the fiber at elevated temperatures under the restraints imposed by the yarn or fabric construction. It is characteristic of the fibers of this invention that While tensions up to 1 g.p.d. may reduce the initial crimp (CI) of the fiber, such tensions have little or no effect on the ultimate, or developable, crimp (CD). Thus, it is possible to start with a tow of, say, 10% CI, 8% CD, and to process that tow through a Pacific converter, pin drafting, roving and spinning to produce a yarn in which the fibers have CI of about 5% but a retained CD of 8%. Such fibers would be considered crimpable in this context even though originally CI exceeded CD. A convenient test of crimpability in this context may be carried out by measuring CI and CD as previously described but subjecting the fibers to a load of l g.p.d. for 30 minutes before measuring CI and then boiling off the fiber and measuring CD in the normal manner. The staple or tow fiber will be classified as crimpable if CD is greater than CI after this procedure.

It is also important that crimp frequency be stable to (i.e., resilient under but not appreciably changed by) the loads, temperatures and plasticizing agents the fibers may be subjected to in processing and ultimate use. In a crimpfrequency-stable fiber CF as measured in the test corresponds to that of the surface fibers (which largely determine tactility) after, for example, yarn or fabric boil-ofl? (where loads encountered by the external fibers would be significantly lower than those encountered by internal 21 fibers or in the test), heat setting, or dyeing. Such stability appears as a unique advantage of fibers of this invention, which rely on differences in crystalline conformation. Typical bicomponent fibers of the art, crimp to varying frequency depending on environmental conditions to which they are subjected.

While most of the immediately foregoing discussion and the following examples are related to woolen and worsted staple processing and fabrics, similar advantages can be attained in blends with cellulosics and other fibers blended with suitably crimped and/or crimpable staples of this invention and processed on the cotton system, for example.

EXAMPLE XX This example illustrates the utility of the fibers of this invention in preparation of worsted fabrics of improved bulk and tactility.

A 98/2 mol-ratio copolymer of PPT and ethylene sodium sulfo-isophthalate of 0.63 intrinsic viscosity and a 98/2 mol-ratio copolymer of PET and ethylene sodium sulfo-isophthalate of 15.0 relative viscosity are spun in a 35/65 ratio to side-by-side round bicomponent fibers as in Example V, except that extrusion temperature is 290-295 C. and windup speed is 530 y.p.m. (485 m./min.). The filaments are drawn to 364% of their spun length in a bath of water at 83 C. and annealed at constant length at 180 C. for 28 seconds. Tow properties are: tenacity 2.2 g.p.d., elongation 21.1%, CI 3.6%, CD 13.5%, CF 9.6 crimps/extended inch (3.8 crimps/extended cm.) and SS 2.5%.

A 1/ 27 worsted count yarn is spun on the worsted system to comprise 55% of the fiber of this example (which has been cut to 3" (7. 6 cm.) staple) and 45% 64-70s wool. The yarn is woven to a 2 x 2 twill and mill-finished in parallel with a similar fabric comprising 55/45 commercial polyester staple/wool. An improvement in bulk (ASTM bulk 2.30 vs. 2.08 cc./gm.) is observed for the bicomponent-fiber blend fabric, which in addition has a pleasant, more wool-like handle.

EXAMPLE XXI This example illustrates the effect of varying annealing conditions on crimp properties in the range preferred for staple. A 50/ SO-ratio bicomponent staple is prepared with a PET polymer of 20 relative viscosity as sheath and a PPT of 0.8 intrinsic viscosity as an eccentric core, using a spinneret such as described in FIG. 1 of the Breen US. Pat. 2,987,797, a spinning temperature of 267 C., and a windup speed of 1000 y.p.m. (915 m./min.) to yield a yarn denier of 1150, 120 filaments. Bobbins of the spun yarn are combined to form a 37,950-denier tow, which is drawn in water at 90 C. to 330% of its spun length and annealed n rolls at a series of temperatures, while stretching an additional 10% during a 30-second exposure. The results are summarized in Table 12.

TABLE 12 Crimp properties, as measured at 1.5

mg. en. a

Anneal. SS,

Bulky fabrics may be obtained from Item D by two different techniques as illustrated ,by the following test.

Item D is processed on the worsted system (as 3.5-inch (8.9 cm.) staple) to 20/1 cotton-count 55/45 polyester/ wool blend yarn with 14 t.p.i., then woven to a 2 x 2 twill fabric having a weight of 6.5 oz./sq. yd. (222 gms./sq. meter) after finishing. The fabric is divided and finished by two methods. Part 1 is scoured at the boil, dyed, lightly fulled and heat-set at 160 C. for 3 minutes. Part 2 is similarly finished except that the fabric is heat-set at 160 C. for 5 minutes, While being held at constant length and width, prior to the initial boil-off. This fabric annealing step approximates that of the annealing given Item A yarn.

Both parts of Item D fabric are bulky, but the bulk of Part 1 fabric is characteristic of that obtained by a mixed-shrinkage mechanism; it has a soft hand and a somewhat fuzzy surface. Part 2 fabric, on the other hand, comprises filaments of spiral crimp, and has a more resilient hand, more even surface and a desirable degree of stretchiness, which characteristics are attributable to the helical crimp of the bicomponent staple. These characteristics are enhanced rather than lost, as a result of taut annealing before boil-01f.

EXAMPLE XXII A series of PPT/ PET staples in which each component contains 2 mol percent ethylene sodium sulfoisophthalate in copolymerized form, is prepared by means taught in the preceding examples to have a range of crimp frequencies. They are blended in 70/30 ratio with wool, processed on the worsted system to 1/30 worsted count yarns with 14 t.p.i. and knitted on a 20-cut machine to tubing which is finished with a boiling scour, piece dyed and tumble-dried.

Results on tactility are summarized in Table 13, with, as comparison items, similar fabrics comprising wool and a bicomponent fiber more typical of those of the prior art.

TABLE 13 Fiber CF: Tactility 2 5 Slick-lean. 9 Wool-like.

14 Do. 17 Harsh, wool-like. 21 Do. 9(woo1) 52 Harsh Fabric prepared in a similar manner from side-by-side bicomponent fiber comprising PET and a /15 copolymer of PET and poly(ethylene isophtlialate) in a 50/50 crosssectional ratio.

2 Subjective evaluation.

EXAMPLE XXIII This example illustrates utility of a sheath-core bicomponent fiber comprising PET and poly(tetramethyl terephthalate) (PET) in staple form.

A 50/50 PET/PBT bicomponent yarn is prepared with a 21 relative viscosity PET as sheath and a 0.95 intrinsic viscosity PBT as eccentric core using a process similar to that of Example XXI. Spinning temperature is 285- 290 C., windup speed 500 y.p.m. (457 m./min.), yarn count 1250 denier, filaments. Seventy-five bobbins are combined as a tow, which is drawn to 371% of its as-spun length in water at 90 C. It is annealed on rolls at 180 C. for 33 seconds while stretching an additional 10% of its drawn length. The resulting fiber exhibits SS 3%, CI 14%, CD 17%, and CF 14 c.p.i.

The tow is cut to 3.5 inch (8.9 cm.) staple and processed to 55/45 polyester/wool yarns with 20/1 cotton count and 18 t.p.i. Processibility is found to be satisfactory despite the rather high crimp. Crimp development and bulk of the boiled-01f wool blend yarns are similar to those of Item A, Example XXI, or of Example XX.

23 EXAMPLE XXIV I A series of 3 inch (7.6 cm.) staples is prepared in a manner paralleling that of Example XX, except that annealing and other processing conditions are varied to produce a range of CI. Table 14 summarizes the results of carding these staples. As will be seen, a CI of about 8 is borderline-to-satisfactory for this method of textile processing. CI of or less is preferred. It has been found, however, that higher CI tow (about 9%) processes in a satisfactory manner on the Pacific Converter to yield 14 turns twistloW-nep-level yarns.

Crimp properties measured on single filaments of the TABLE 14 Spinning Drawing Annealing Wt. ratio, Cross Speed, Temp. Temp. Temp. Time, Card web PET/PPT section y.p.m. C. Ratio 0. C. see. CI appearance 553 292 4. 0 90 180 28 3.0 No neps.

575 291 4. 3 80-85 180 l 28 7. 5 Excessive neps.

552 293 l 3. 6 85 180 40 7. 9 No neps.

553 292 4. 3 90 180 28 8. 3 Excessive neps.

1 Estimated values.

NorE.PET=copolymer of PET containing 2 mol percent of ethylene sodium sulfoisophthalate and having relative viscosity of 12.5; PPT =copolymer of PPT containing 2 mol percent of ethylene sodium suliolsophthalate and having an intrinsic viscosity of 0.7; SBS=side-by-side; Sh/C=eccentnc sheath-core.

EXAMPLE XXV A side-by-side bicomponent fiber comprising 65% of a 98/2 mol-ratio copolymer of PET and ethylene sodium sulfoisophthalate of 13.5 relative viscosity containing 0.25% tetraethyl silicate and 35% of a 98/2 mol-ratio copolymer of PPT and ethylene sodium sulfoisophthalate of 0.63 intrinsic viscosity is spun at 292 C. from a 120- hole spinneret. The filaments are quenched with roomtemperature air and wound-up at 525 y.p.m. (480 m./ min.) to give a spun denier of 12 dpf. Yarn from 75 packages of 1440 denier each, is drawn to 407% of its as-spun length in water of 85 C. to yield a nominal 3 d.p.f. tow, which is annealed at constant length by exposure to rolls heated to 180 C. for 28 seconds. It is mechanically crimped to 68 c.p.i. (2.4-3.4 c.p. cm.) and cut to 3-inch (7.6 cm.) staple. Properties are: tenacity 2.3 g.p.d., elongation CF 10 c.p.i., CD 12.5%, CI 3.7% and skein shrinkage 3.0%.

The staple is blended 50/50 with a commercially available, basic-dyeable polyester staple intended for use in pill-resistant fabrics and processed to 2/ 30 worsted count yarn with 12 t.p.i. Z-twist in the singles and 6 t.p.i. S- twist in the plied yarn. The yarn is knitted at 13 courses/ inch (5.1 courses/cm.) on a 12-cut circular knitting machine. The resulting fabric is scoured and can be piecedyed at the boil using a disperse dye formulation comprising 5 g./liter of a carrier consisting of equal parts of dimethyl terephthalate and benzanilide. Bulk is developed during scouring and dyeing. The finished fabric has excellent stitch clarity and good bulk, resilience and liveliness. Tactile aesthetics approach those of an all-wool counterpart. The test fabric has a weight of 8.63 oz./yd. (292 gms. /1n. and bulk of 5.47 cc./ g. under a standard 3 g./cm. load and 4.37 cc./gm. under a load of 40 g./ cm.

EXAMPLE XXVI This example illustrates the advantage of delaying the development of the major portion of the bicomponent crimp until the fiber is in yarn or fabric form.

Bicomponent staple is prepared substantially according to the procedure of Example XXV to have CI 3.7% and CD (as measured under no boil-off load). Card sliver is prepared; it is used to prepare worsted yarns by each of three process sequences:

various structures developed in this example are summarized in Table 16.

1 CD and CF are measured after boiling 011 or steaming of the fibers in the form indicated. N o restraining load is used during this relaxation.

Upon relaxing, yarn A bulks to about twice the diameter of yarn C. The basis for this is seen in comparison of CI and OD for these yarns. Essentially all the developable crimp is already present in yarn C (17.5 CI vs. 14 OD), while the bulk of the crimp is yet to be developed in yarn A.

The bulk of yarn B is equivalent to that of yarn A after boil-off. This is explained by the fact that the crimp previously developed in sliver B is eliminated in pindrafting and is redevelopable in the yarn.

EXAMPLE XXV II This example illustrates properties obtained in bicomponent-fiber structures more representative of the art.

Side-by-side bicomponent staple comprising as one component PET of 20 relative viscosity and as the second a 15 copolymer of bis(hydroxyethyl) terephthalate and bis(hydroxyethyl) isophthalate of 40 relative viscosity. The polymers are spun at a block temperature of 298 C. and wound up at 989 y.p.m. The spun denier is 810, 60 filaments. A tow of 81,000 denier comprising such filaments is drawn to 400% of its spun length in a water bath at C. and annealed on rolls for 33 seconds at a series of temperatures. Results are given in Table 17.

TABLE 17 Crimp properties Anneal r011 SS, D, CF

Item temp., 0. percent percent percent (c.p.i.)

Off 24 6. 2 16. 0 30 'Note that as annealing temperature is increased, C1) decreases, in contrast to the results obtained with the bicomponent fibers of this invention.

Items A, C and E are processed to 55/45 wool-blend worsted yarns of 20/1 cotton count which are woven to 2 x 2 right-hand twill fabrics. The fabrics are finished in a standard manner for millfinished worsteds. All fabrics are judged objectionably harsh, the harshness increasing with increasing crimp properties (A through E), although similar fabric made from fibers of this invention with crimp properties similar to Item A had a pleasing tactility (e.g. Example XX). Microscopic examination shows the surface of the fabrics to be covered by tightly coiled fibers. It is postulated that the fibers coil on high temperature treatment during fabric heat-setting. This is confirmed by relaxing a sample of item A tow at tenterframe temperatures (150 C. or higher under essentially no restraint), whereupon the fiber develops more than 50 crimps per inch. Fibers of this invention maintain nearly their measured crimp frequency when subjected to fabric heat-setting conditions, as illustrated in Example XXVIII.

EXAMPLE XXV'HI This example further illustrates the unique stability of the helical crimp in bicomponent fibers of this invention when subjected to the plasticizing action of dye carriers. The importance of crimp frequency to aesthetics makes this characteristic a valuable contributor to the development of superior textile fibers.

Bicomponent staple is prepared in accordance with the procedure of Example XX. Crimp frequency before and after various treatments, as noted, are summarized in Table 18, as compared with fiber such as that illustrated by Example XXVII.

TABLE 18 As Example XXVII s Example Sample Sample Fiber XX A B Crimp frequency (e.p.i.): Initial. After relaxed boil-off:

In water (b) In 5 g./l., Carrier A 1 (c) In 5 g./l., Carrier B 2 After relaxed heat setting at 155 C.

for 40 seconds 1 Equal weights mixture of dimethyl terephthalate and benzanilide. 2 Orthophenylphenol.

EXAMPLE XXIX This example illustrates the use of controlled relaxation to modify the crimp characteristics of bicomponent fibers of this invention.

A side-by-side bicomponent fiber comprising 70% of a 12.3 relative viscosity copolymer of 98 mol-percent IET and 2 mol-percent poly(ethylene sodium sulfoisophthalate) and containing 0.25 wt.-percent tetraethyl silicate, and 30% poly(tetra-methylene terephthalate) of 0.8 intrinsic viscosity is spun at 280 C. from a 120-hole spinneret. The filament bundles from forty bobbins are combined and drawn to 3.7 ratio in an aqueous draw bath at 85 C. After drawing, the tow bundle is relaxed by con veying at 80 ft./min. once around the first of 2 pairs of heated rolls (1st pair roll temp., 185 C., 2nd pair, 195 C.) in an enclosure (air temp. 195 C.), then 9 times around the second pair operating at a surface speed of 60 ft./min. During the relaxation step the filaments develop a relatively high frequency spiral crimp (about 14 crimps per inch) of low amplitude (CI=3% On subse quent boil-01f under 1.5 mg./den. load, CD is found to be 9%; CD (after boil-off under no load) is found to be 18%; OF remains about 14 crimps/ in. in either case.

By contrast, similar bicomponent filaments processed without the controlled relaxation step to have a CD of 9% are found after boil-off to have only 6 crimps/ in. and a CD (after boil-01f under no load) of 32%. The higher frequency and lower CD of the filaments prepared by 26 controlled relaxation can be used to produce staple fibers which confer better visual aesthetics and reduced stretchiness in fabrics made from skein-dyed yarns.

EXAMPLE XXX A side-by-side trilobal bicomponent filament in which one component is a copolymer of ethylene terephthalate (98 mol percent) and ethylene sodium sulfoisophthalate (2 mol percent) having a relative viscosity of 12 and the other component is a copolymer of tetramethylene terephthalate (98 mol percent) and ethylene sodium sulfoisophthalate (2 mol percent) having a relative viscosity of 21 is extruded at 265 C. from a 60-hole precoalescence spinneret to produce a yarn having a denier of 1220. The volume ratio of the ethylene terephthalate copolymer component to the tetramethylene terephthalate copolymer component is 75/25. A tow is prepared by combining 45 ends of the above yarn and drawn at a ratio of 3.95 in a C. Water bath. The drawn tow is subjected to light mechanical crimping in a stuffer box crimper and then relaxed in a heated atmosphere at C. for 5 min. to develop crimp. The crimp index after this treatment is 22%. The tow is then stretched at room temperature to 1.20 times its original crimped length to remove part of the crimp and then passed in the stretched state around heated rolls for 24 seconds at C. The resulting filaments have a CI of 7%, a CF of 12 crimps/in, a CD after boil-01f under no load of 13% and a CD" after boil-off under 1.0 mg./den. load of 9%.

In the practice of this invention, additives normally employed in the manufacture of synthetic filaments may be used and are substantially without adverse effect on properties of the bicomponent filaments of this invention. It is possible, for example, to add antistatic agents, delusterants, fluorescent brighteners, dyes, pigments, surface rougheners and the like to one or both components within reasonably wide limits without adversely influencing differential shrinkage, crimp, stretch or stretch-recovery appreciably. Addition of topical finishes may also be practiced.

This invention is applicable to the production of fiber of any cross-sectional shape. Those which have been employed and found satisfactory include, for example, round, oval, ribbon, double round and trilobal.

While the exemplified development of crimp by shrinking has exclusively involved treatment in hot or boiling water in the examples herein, it is to be recognized that operative alternatives exist which also would develop the crimp. Treatment with a transitory plasticizer, for example, can lower the glass transition temperature of a polymer sufiiciently to accomplish the necessary shrinkage for crimping at a temperature substantially below the normal second-order transition temperature; it is conceivable that such a treatment could shrink the filament at room temperature. Further, polymers vary widely in glass transition temperature, and treatment at temperatures substantially above 100 C. may be necessary to shrink filaments made from high glass-transition-temperature components.

The novel filaments of this invention can be used in light-weight stretch fabrics since use in this type fabric highlights the novel combination of properties oifered by these filaments. In addition, as described in Examples XII, XVII, XVIII and XX-XXVIII, the bulk afforded by many of the spontaneously crimpable filaments of this invention is useful in a variety of fabrics where bulk and tactility are emphasized rather than stretch and power. The filaments of this invention are also useful as replacement for elastomeric or twisted and heat-set filaments in yarn structures produced by the core spinning processes illustrated in U.S. Pats. 2,777,310 and 2,880,566, as examples.

The broad range of available fabric stretch, power, bulk, tactility and surface appearance available with the filaments of this invention admirably equip them for use in a wide range of end uses. Among the suitable end uses are upholstery, slip covers, carpets, hosiery, half-hose or socks, support hose, ski pants, le'ot-ards, boxer shorts, swim wear, sweaters, undergarments where support or bulk is needed, lingerie, brassieres, girdles, blouses, shirts, mens or womens suitings (for better fit, wrinkle recovery), etc. Suitable fabric types include Wovens, knits and warp-knits as well as nonwoven, or felt-like, fabrics, especially where bulk durability, tactile and visual aesthetics, high power of recovery from stretch and/or simplicity and economy of fabrication are desirable.

The preceding representative examples may be varied within the scope of the present total specification disclosure, as understood and practiced by one skilled in the art, to achieve essentially the same results.

The foregoing detailed description has been given for clearness of understanding only and no unnecesary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described for obvious modifications will occur to those skilled in the art.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A helically crimpable composite filament comprising a laterally eccentric assembly of at least two synthetic polyesters, the first of said two polyesters being partly crystalline in which the chemical repeat-units of its crystalline region are in a nonextended stable conformation that does not exceed 90 percent of the length of the conformation of its fully extended chemical repeat-units and which assumes a position on the inside of crimp helices formed when the assembly crimps, the second of said two polyesters being partly crystalline in which the chemical repeat-units of the crystalline region are in a conformation more closely approaching the length of the conformation of its fully extended chemical repeat-units than the first defined polyester.

2. The helically crimpable composite filament of claim 1 wherein the chemical repeat-units of the crystalline region of the second polyester are in a conformation that is 95% or more of the length of the conformation of its fully extended chemical repeat-units.

3. The helically crimpable composite filament of claim 2 wherein the filament is a bicomponent filament.

4. The helically crimpable bicomponent filament of claim 3 in which the first polyester is selected from the group consisting of poly(trimethylene terephthalate), poly(tetramethylene terephthalate), poly(trimethylene dinaphthalate) and poly(trimethylene bibenzoate).

5. The helically crimpable bicomponent filament of claim 4 in which the first polyester is poly(trimethylene terephthalate) and the second polyester is poly(ethylene terephthalate 6. The helically crimpable bicomponent filament of claim 5 wherein each polyester employed contains minor amounts of ethylene sodium sulfoisophthalate in copolymerized form.

7. The helically crimpable bicomponent filament of claim 4 in which the first polyester is poly(tetramethylene terephthalate) and the second polyester is poly(ethylene terephthalate) 8. The helically crimpable bicomponent filament of claim 7 wherein each polyester employed contains minor amounts of ethylene sodium sulfoisophthalate in copolymerized form.

9. The helically crimpable composite filament of claim 1 in the form of staple.

10. A helically crimped composite filament comprising a laterally eccentric assembly of at least two synthetic polyesters, the first of said two polyesters being partly crystalline in which the chemical repeat-units of its crystalline region are in a nonextended stable conformation that does not exceed percent of the length of the conformation of its fully extended chemical repeat-units and is positioned on the inside of the helical crimps, the second of said two polyesters being partly crystalline in which the chemical repeat-units in the crystalline region are in a conformation more closely approaching the length of the conformation of its fully extended chemical repeatunits than the said first polyester.

11. The helically crimped composite filament of claim 10 wherein the chemical repeat-units of the crystalline region of the second polyester are in a conformation that is or more of the length of the conformation of its fully extended chemical repeat-units.

12. The helically crimped composite filament of claim 11 wherein the filament is a bicomponent filament.

13. The helically crimped bicomponent filament of claim 12 in which the first polyester is selected from the group consisting of poly(trimethylene terephthalate), poly(tetramethylene terephthalate), poly(trimethylene dinaphthalate) and poly(trimethylene bibenzoate).

14. The helically crimped bicomponent filament of claim 12 in which the first polyester is poly(trimethylene terephthalate) and the second polyester is poly(ethylene terephthalate) 15. The helically crimped bicomponent filament of claim 14 wherein each polyester employed contains minor amounts of ethylene sodium sulfoisophthalate in copolymerized form.

16. The helically crimped bicomponent filament of claim 12 in which the first polyester is poly(tetramethylene terephthalate) and the second polyester is poly(ethylene terephthalate).

17. The helically crimped bicomponent filament of claim 16 wherein each polyester employed contains minor amounts of ethylene sodium sulfoisophthalate in copolymerized form.

18. The helically crimped composite filament of claim 10 in the form of staple.

References Cited UNITED STATES PATENTS 2,465,319 3/1949 Whinfield et a1. 26075 2,931,091 4/1960 Breen 161173 ROBERT F. BURNETT, Primary Examiner L. KOECKERT, Assistant Examiner US. Cl. X.R.

@FKCE PO-wso UNHTED STATES NATE s/ 69) QN'NMNN'NN oN PmmNo. g '/1,379 Dated June 20, 1972 Inventor(s) EVAN FRANKLIN EVANS and NORWIN CALEY PIERCE It 1e certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 12, line 6, "The filaments are" should read The 31 filaments are Column 12, line 32, Table 3, last column, the numbers 22 and 27 should be reversed.

Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

EDWARD MoFLETcHERflR. ROBERT GOITSCHALK Attesting Officer Commissioner of Patents

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