US 3117055 A
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1964 E. GUANDIQUE ETAL 3,
NON-WOVEN FABRIC Filed Dec.
4 lo ELONGATION INVENTORS ESPERANZA PARRISH (nee GUANDIQUE) MANFRED KATZ Ta a 2.73M
ATTORNEY United States atent 3,117,055 NQN-WOVEN FABRIC Esperanza Guandique, now by change of name Esperanza Parrish, and Manfred Katz, Wilmington, Del.,, assignors to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Dec. 15, 1959, Ser. No. 859,640 12 Claims. (Cl. 161170) This invention relates to fabrics and more specifically to novel non-woven fabrics prepared from synthetic organic polymer fibers.
Fabrics in general fall into two classes: woven and non-woven. Woven fabrics usually include knitted fabrics and may be defined as fabrics formed by the interlacing in a predetermined regular geometrical pattern of one or more long lengths of yarns or filaments. Non-woven fabrics, on the other hand, are usually formed by a random or controlled deposition of filamentary strands to form a sheet or batt followed by binding these strands in some way to provide strength and dimensional stability.
Although each type of fabric has advantages for applications in specific areas, there are certain fundamental property differences which have hitherto been considered as inescapable adjuncts of the method by which the fabric was formed. Woven and knitted fabrics have generally been recognized as stronger, more flexible, more readily prepared in light weights, and more drapable. Non-woven fabrics, such as felts, have, for the most part, been confined to applications such as hats,
lter cloths, and so on, because of the ease with which they can be formed into a dense material of low porosity and also because of the low cost of preparing the finished fabric structure directly from the individual fibers.
The advantage of low processing cost is one of the very desirable features of non-woven fabrics. All of the various processing steps which are required in the preparation of woven and knitted fabrics add considerably to the cost of the final product. Thus, in the formation of a woolen suiting material, the wool fibers must be formed into a yarn, the yarn must be twisted or plied, and the resulting final yarn product must then be Woven into a fabric. It would be extremely desirable to provide a process which would involve simple welllmown papermaking procedures but would produce a textile fabric having the properties of a woven fabric.
Although low cost and certain property advantages of non-woven fabrics have led to the employment of these materials in a number of specific end uses, limitations which have hitherto been considered a necessary part of the non-woven structure have eliminated them from many apparel applications. Womens skirts are occasionally made from certain non-woven felts, but in general these have enjoyed very limited appeal. It has not been found practical to make womens dresses, mens and womens suiting, coatings, sweaters, and the like from non-woven fabrics, one of the major reasons being that non-woven fabrics have heretofore been rather stiff and bulky and, therefore, possessed poor drapability.
It is an object of this invention to provide new nonwoven fabrics of synthetic fibers, which fabrics exhibit a combination of high tensile strength and high drapability, thereby providing aesthetic and physical properties comparable to those of woven or knitted textile fabrics of the same weight and fiber composition.
According to this invention there is provided a non woven fabric of synthetic organic fibers, said fibers containing at least 30 crimps per inch, and being bonded at spaced points uniformly and randomly distributed throughout the fabric so that the average straight length of fiber between two points of bonding of that fiber is 3,117,055 Patented Jan. 7, 1964 ice Percent binderx i/Mz' of binder 40 where the percent binder is based on the total weight of the fabric, including the binder. The modulus (Mi) of the binder is between about 0.002 and about 25 grams per denier.
The individual filamentary components of fabrics of this invention possess a high degree of lateral freedom and flexibility in three dimensions between intersection points and points of bonding, thereby providing these fabrics with a high degree of drape and softness, high tensile strength, low bulk and a soft handle in the same range as woven fabrics. The fabrics of this invention are characterized by a fabric density of 0.28 to 0.7 g./cc., a drape stiffness of not over 1.0 inch, a ratio of tensile strength to drape stiffness of at least 12.0 p.s.i., and a sonic velocity-elongation differential of at least 1.3. They are, therefore, readily distinguished from papers on the one hand and conventional thick and bulky non-woven felts on the other. The non-woven fabrics of this invention are equivalent in handle, thickness, drapability, strength and other aesthetic and physical properties to a wide spectrum of woven fabrics.
The invention will be more readily understood by reference to the drawings.
FIGURE 1 shows schematically one type of apparatus useful for producing the products of this invention.
FIGURE 2 shows a portion of a non-woven filamentary structure of this invention bonded at points of fiber crossing.
FIGURE 3 illustrates the structure of a larger portion of a fabric of this invention greatly enlarged.
FIGURE 4 is a graph comparing physical characteristics of a fabric of this invention with those of a conventional woven fabric and a paper of the same filamentary material.
Referring to FIGURE 1, freshly formed filaments 1 issuing from spinneret 2 orifices 2.4 are passed through aspirator jet 3' to 'which is supplied air under pressure through inlet 4 (air flow indicated by arrow). Aspirator jet 3 is charged to high positive potential (+E), in the case shown, by a source 5 of electrostatic potential. Source 5 is connected to aspirating jet 3 via lead 6 and the opposite-charge pole is grounded through lead 7. Upon passing aspirator jet 3, the charged filaments 8 are collected into sheet 9 on receiver 10- which is supported by means indicated fragmentarily at 11. Receiver 10 is either grounded through lead 12 or, alternatively, charged opposite to the charge of filaments 8 via lead 13 from source 5, interrupting then lead 12 to ground at switch 14.
FIGURE 2 is a simple illustration greatly magnified of the structure of a fabric of this invention containing crimped andl/or looped filaments 15 bonded at spaced points 16 by an adherent such as. a fibrid.
FIGURE 3 is an enlarged portion of a fabric of this invention comprising a multitude of the portions illustrated in FIGURE 2 and illustrating the uniformity of distribution of fibers, random disposition of fibers and uniformity of spaced points of bonding throughout the fabric.
FIGURE 4 compares the change in sonic velocity with elongation of non-woven fabrics of this invention, conventional woven fabrics, and paper products made from the same materials. It can be seen from FIGURE 4 that the physical properties of non-woven fabrics of this invention are almost identical with those of woven fabrics but are quite different from paper products.
The non-woven fabrics of the present invention combine the non-woven structure with its characteristic high dimensional stability and a high degree of drapability, flexibility and handle together with high strength and low bulk.
Drapability is measured by determining the length of fabric which is necessary to cause the fabric to bend from the horizontal plane when under no constraint to such an extent as to contact a declining angle of 415 of slope from the point of departure of contact. A strip of fabric one inch wide is placed upon a block of WOOCl or other horizontal surface. Abutting the horizontal surface of this material is a 4l.5 inclined plane, which at its top adjoins the horizontal surface. The test specimen is placed with its narrow edge at the juncture of the horizontal and the inclined surfaces. It is then moved forward over the inclined surface until the free end touches the 41.5 slope of the testing block. The drape stiffness, designated C, is measured in inches of free length of specimen extending beyond the horizontal surface edge. An equivalent test, the cantilever test of ASTM D1388- 55T, gives values in the range of 50 to 2,000 mg.-cm., in measuring the stiffness of fabrics.
Bulk of a fabric is determined by cutting a square portion of the fabric of uniform thickness, measuring its dimensions, including its thickness, and then calculating its volume. The fabric sample is measured for thickness in accordance with standard test described in A.S.T.M. specification D7653 by means of a conventional fabric thickness caliper device such as an Ames gage (manufactured by B. C. A-mes Company, Waltham, Mass). In the event the fabric sample is embossed, the thickness may be determined more accurately through microscopic examination of the edge of the fabric. The fabric sample is then Weighed and the bulk expressed in terms of volume per unit weight.
Tensile strength is determined on a one-inch strip of fabric in conventional manner employing an Instron tensile tester. For purposes of this invention, tensile strength is determined at room temperature under ambient conditions of 65% relative humidity. The ratio of tensile strength of a fabric to its drape-stiffness is useful for comparing the fabrics of this invention with conventional woven fabrics, felts, and papers. The ratio is calculated by multiplying the tensile strength (lbs./in./ oz./yd. by the basis weight (oz/yd?) and dividing by the drape stiffness (in).
Sonic velocity-elongation differential is a measurement of the effect of fabric elongation (and tension) on the velocity of sound transmission in the plane of the fabric. Measurement of sound velocity in fabrics is well known (see article by W. H. Charch, W. W. Mosely in 29 Textile Research Journal, page 525 (1959)) and involves wellestablished principles and techniques. The velocity of propagation of sound waves in a fabric is dependent on fabric tension and is indicative of certain fabric properties. Woven fabrics, and also the non-woven fabrics of this invention, provide media through which sound travels at a velocity which is strongly dependent on the elongation (and the tension) in the fabric, indicating that both have very similar structural characteristics and properties despite their vastly different coarse structure (e.g., woven vs. non-woven). Other materials, such as felts, papers, and leathers, transmit sound at a nearly constant velocity, that is, substantially independent of the degree of elongation of the structure.
Sonic velocity in a fabric can be measured using a piezoelectric crystal signal source (or other source) to provide Vibrations of the desired frequency. Frequencies in the range of 1,000 to 40,000 c.p.s. are conveniently employed. As a detector, a search transducer (a piezoelectric crystal is again suitable) is used, placed at a fixed distance from TABLE I Velocity at Different Elongations, kIIL/see. Ratio Sheet Material VG%/VO% Nylon paper 1. 25 1. 28 1.31 1. 05 Nylon woven fabric 0. 46 O. 54 0. 62 1. 35 Non-woven (Ex. V 0.33 0.43 0. 54 1. 64 Non-woven (Ex. III) 0. 6O 0. 69 0.79 1. 5
It will be seen that the paper material, while having a high critical sonic velocity value, shows no substantial change as it is tensioned. On the other hand, the woven fabric and the non-woven fabrics of the present invention show a sonic velocity value which increases by at least 30% when the fabric is elongated 6%.
A preferred and highly desirable embodiment of the present invention is a fabric containing continuous filaments of a very highly crimped and convoluted configuration, conveniently prepared by melt-spinning of synthetic filarnents with a cocurrent air stream which simultaneously orients and forwards them while they are also subject to the effect of a high static electrical potential charge between the jet and a collecting device upon which the filaments impinge. Under the influence of the electrical charge, the filaments separate and lay down in a completely random configuration upon the collecting device (a plate or other receiver) and spontaneously crimp and convolute, so that the resulting filament web is made up of fibers having at least 30 c.p.i., and as much as c.p.i. or more. Crilmps are measured by direct observation using a microscope with a scaled eyepiece, or by projection. The filaments are disposed randomly in the fabric and besides being crimped, are doubled, looped and bent to such a high degree that, on the average, any filament in the web has a free fiber length of at least 1.25 times the shortest distance between points of bonding of that filament with other filaments. in this invention a filament crimp is one in which the amplitude of the departure from a straight line is less than 3 times the radius of curvature of the crimp, the latter being always less than 0.5 inch. Filament loops have either an amplitude of departure from a straight line of at least 0.6 inch associated with a radius of curvature of at least 0.2 inch; or a radius of curvature of more than 0.5 inch. By the term free fiber length is meant the length of any fiber portion, between points of bonding of that fiber, measured while that fiber portion is extended sufficiently to remove any crimp or loops therein. Such webs, which may be suitably bonded by co-spun thermoplastic filaments or by fibrids sprayed or flocked onto the web during formation, are strong, soft, drapable, and flexible. Of course, binder fibers or fibrids must have a melting point lower than the fibers to be bound when the bonds are to be produced by heating.
When low-melting binder fibers are co-spun with the crimped filaments, the resulting binder is in the form of a continuous or semi-continuous series of areas, bonding being effected at cross-over points and points of fiber intersection. When fibrid binders are used, particularly in large proportions, the binder material may be in a continuous or semi-continuous reticulated web interlacing and interlocking with the web of continuous or staple fibers. Such continuous or semi-continuous distribution of binder is preferred for the practice of the present invention, because it gives a fabric having an unusually smooth surface and uniform thickness.
In another embodiment, a non-woven fabric of this invention is prepared using from 3%-50% by weight of a fibrid binder and at least 50% by Weight of a spontaneously elongatable synthetic polymer fiber. Preferably these two components comprise in sum at least 85% by weight of the total non-woven structure. The remainder may be any synthetic organic polymer fiber. $uch fabrics have excellent drapability.
In still another embodiment of this invention an elastomeric binder is utilized to prepare a non-woven fabric having a unique and surprising combination of low bulk, high flexibility and high strength, rendering them equivalent to woven apparel and decorator fabrics in physical characteristics. One structure contains at least by weight of an elastome-ric fibrid binder (by which is meant a fibrid binder of a synthetic elastomeric polymeric composition having a modulus of between about 0.002 and about 0.9 gram per denier), together with at least by weight of a spontaneously elon-gatable fiber, the remainder being any synthetic organic fiber. Preferably, the elastomeric fibrid will have a modulus of between 0.002 and 0.1, but the most desirable products contain an elastomeric fibrid with a modulus between 0.005 and 0.05.
The term fibrid is employed herein to designate a non-rigid, wholly synthetic polymeric particle capable of forming paper-like structures. Thus, to be designated a fibrid, a particle must possess an ability to form a Wa terleaf having a couched wet tenacity of at least about 0.002 gram per denier when a multitude of the said particles are deposited from a liquid suspension upon a screen, which waterleaf, when dried at a temperature below about 50 C., has a dry tenacity at least equal to its couched wet tenacity, and a capability, when a multitude of the said particles are deposited concomitantly with staple fibers from a liquid suspension upon a screen, to bond a substantial weight of the said fibers by physical entwinement of the said particles with the said fibers to give a composite waterleaf with a wet tenacity of at least about 0.002 gram per denier. By. acapability to bonda substantial weight of (staple) fibers is meant that at least 50% by weight of staple based on total staple and fibrids can be bonded from a concomitantly deposited mixture of staple and fibrids. In addition, fibrid particles have a Canadian freeness number between 90 and 790 and a high absorptive capacity for water, retaining at least 2.0 grams of water per gram of particle under a compression load of about 39 grams per square centimeter. Any normally solid wholly synthetic polymeric material may be employed in the production of fibrids. By nonma-lly solid is meant that the material is nonfluid under normal room conditions.
It is believed that the fibrid characteristics recited above are a result of the combination of the morphology and non-rigid properties of the particle. The morphology is such that the particle is non-granular and has at least one dimension of very minor magnitude relative to its largest dimension, i.e., the fibrid particle is fiber-lilac or filn1-like. Usually, in any mass of fibrids, the individual fibrid particles are not identical in shape and may include both fiber-like and film-like structures. The nonrigid characteristic of the fibrid, which renders it extremely supple in liquid suspension and which permits the physical entwinement described above, is presumably due to the presence of the minor dimension. Expressing this dimension in terms of denier, as determined in accordance with the fiber coarseness test described in Tappi 41, 17SA7A, No. 6 (June) 1958, fibrids have a denier no greater than about 15.
Complete dimensions and ranges of dimensions of such heterogeneous and odd-shaped structures are ditlicult to express. Even screening classifications are not always completely satisfactory to define limitations upon size since at times the individual particles become entangled with one another or wrap around the wire meshes of the screen and thereby fail to pass through the screen. Such behavior is encountered particularly in the case of fibrids made from soft (i.e., initial modulus below 0.9) polymers. As a general rule, however, fibrid particles, when classified according to the Clark Classification Test (Tappi 33, 294-8, No. 6 [June] 1950) are retained to the extent of not over 10% on a l0-mesh screen, and retained to the extent of at least on a ZOO-mesh screen.
Fibrid particles are usually frazzled, have a high specific surface area, and as indicated, a high absorptive capacity for water.
Preferred fibrids are those the waterleaves of which when dried for a period of twelve hours at a temperature below the stick temperature of the polymer from which they are made (i.e., the minimum temperature at which a sample of the polymer leaves a wet molten trail as it is stroked with a moderate pressure across the smooth surface of a heated block) have a tenacity of at least about 0.005 gram per denier.
Fibrid particles and their preparation are described in more detail in Belgian Patent 564,206. Fibrids can be prepared from a number of polymeric compositions, and a wide range of such fibrids can be used in the present invention, leading to a spectrum of fabrics as indicated above.
In place of the fibrid binders already described, other synthetic polymer resin binders can be employed in the practice of the present invention. Generally, when the polymeric resin binder has an initial modulus of more than 0.9 g./d., less than about 25% resinous binder based on the total weight of the fabric should be utilized to obtain fabrics having properties of woven fabrics of the same \weight and fiber content. if, for any reason, it is desired to employ more than 25% of a resin binder, an elastomeric binder should be employed in order to obtain good physical properties.
One of the components used in preparing a preferred non-woven fabric of the present invention is a self-clongatable fiber. This may be defined as a fiber which, upon suitable thermal treatment, exhibits an internally generated increase in length of from 3% up to 25% of its original length. The phenomenon of spontaneous elongation in wholly synthetic organic polymer fibers is known and described, for example, in Belgian Patent 566,145, granted September 27, .195 8. This patent deals with spontaneously elongatable polyester fibers. However, spontaneous elongation as a phenomenon has been observed in other synthetic organic polymer fibers as well. For example, a polyamide prepared by reacting p-xylylene diamine and azelaic acid has been observed to be spontaneously elongatable and is suitable for use in the fabrics of the persent invention. Condensation polymers generally such as polyesters, polyamides, and polyurethanes can be employed in the present invention. in addition to condensation polymer fibers, acrylic, polyolefin, and other addition type polymers can be used to prepare products of this invention. Polyester fibers are the preferred selfelongatable fibers for the staple non-woven structures of this invention, while both polyarnide and polyester fibers are preferred for continuous filament products.
As indicated in the foregoing description, two critical and significant components for one of the non-woven fabrics of this invention are self-elongatable fiber and a binder. However, it is possible to employ, in addition to those two components, a minor amount of other fibrous materials. These materials include conventional staple filaments of such materials as polyamides, polyesters, polyurethanes, acrylic fibers, polyethylene, polypropylene, rayon staple, cellulose acetate, and the like. In general, either crimped or uncrimped fibers of this type may be used so long as the other requirements of this invention are met. Uncrimped fibers give greater improvement in dimensional stability, while crimped fibers permit greater bulkiness. The use of such fibers in the fabrics of the present invention can be advantageous in that the presence of these fibers can be employed for additional strength, more uniform fabric surface appearance, greater dimensional stability, additional dyeability, or other properties which are connected with or dependent upon the characteristics of the fiber material employed. The choice of such fibrous material will depend upon the end result desired, and, if the amount of such fiber is kept below 15% of the total weight of the fabric, fabric characteristics which are unique in the fabrics of the present invention will not be impaired and may sometimes be improved.
in addition to the fibrous components, moderate amounts of non-fibrous material can be employed in the fabrics of the present invention. Such non-fibrous maerials can be added to an extent not greater than by weight of the total structure to obtain a wide variety of particular product advantages such as color, surface properties, and the like. In particular, it has been found suitable and desirable to add small quantities of inorganic particulate matter, such as pigments, clays, metal oxides, and similar structures. These may be added by incorporation into the fibrid structure before the non-woven fabric of this invention is formed therefrom. 'In addition, it is also possible to include particulate structures derived from synthetic organic polymer resins, synthetic elastomers, and the like.
The preparation of non-woven materials from wholly synthetic sheet forming particles is described in some detail in Belgian Patent 564,206. For larger-scale operations, it is usually desirable to prepare non-woven materials by a continuous process using, for example, papermaking machinery such as the Fourdrinier machine and other comparable pieces of apparatus, as Well as carding machines, Rando-Webber machines, and other equivalent devices.
In producing fabrics of the present invention, fibrids or resins are used to bond fibers together in a non-woven structure of high original strength. In general, it is then preferred to press the fabric at an elevated temperature and thereby consolidate the structure. In the pressing operation a certain amount of fusion of the binder material takes place. The precise degree of fusion will depend upon the temperature of pressing, the time of pressing, and the pressure involved. In one preferred embodiment, fibrid binder particles are used, and under extreme conditions of high heat, long pressing time and high pressure, the fibrid particle identity is lost and the fibrid particles become fused more or less completely into the nonwoven structures. Under more moderate conditions of temperature and pressure, the fibrids are fused Without complete destruction of their particulate and specific nature.
The pressing operation, which will be described in further detail in the examples below, is a desirable adjunct of the present invention and leads to superior products. However, it is possible to prepare non-woven fabrics in accordance with the teaching of this invention which have high as-formed strength prior to any pressing operation, and such fabrics are useful as such. When pressing is employed to form a fabric of high strength, it is also possible at the same time to impress on the fabric a pattern or embossed effect of some type for the purposes of improved appearance, modified surface behavior or other known modifications. Pressing may be continuous throughout the entire fabric surface or it may be intermittent or in a pattern, such as cross-lines, diamonds, circles, isolated dots, and so on.
In the production of the preferred non-woven fabrics already described, the embossing procedure offers a valuable improvement in the woven-like characteristics which are desired. For example, when pressing between screens is employed, the self-elongatable fibers elongate and assume a third-dimensional configuration on tne surface of the fabric, due to penetration of portions of the fibers into the interstices of the screen. Similar response to other preferred embossing techniques is also possible, and such third-dimensional configurations make an important contribution to the suppleness and drapability of the products obtained thereby. In general, to obtain products of greatest interest, it is usually found that a moderate degree of pressing is most satisfactory.
The binders useful in this invention may be any synthetic organic polymeric material having a modulus between about 0.002 and about 25 grams per denier. Representative of elastomeric binders in this class are the various butadiene-styrene copolymers containing from 30% to 70% combined butacliene, and also terpolymers of butadiene, styrene, and acrylonitrile. Other useful elastomeric binders include copolymers and terpolymers containing a major proportion of poly(rnethyl acrylate) and lesser amounts of other acrylates and acrylic acid; a mixture of 98% polymethyl methacrylate plus 2% glyciclyl methacrylate in the amount of 10 parts, and about 86 parts of the acrylate ester copolymer mentioned above; a terpolymer containing methyl acrylate, methyl methacrylate, and acrylic acid; a copolymer of ethyl acrylate with 2% acrylic acid; a mixture of 49 parts polyhexylmethacrylate, 49 parts polyethyl acrylate, and 2 parts polyacrylic acid prepared by solution polymerization in benzene using benzoyl peroxide as initiator; poly(ethylene/propylene) containing 3% dicumyl peroxide. Another useful elastomeric binder is obtained by reacting poly(tetramethylene ether) glycol of approximately 1000 molecular weight with tolylene 2,4- diisocyanate to give a glycol-terminated macrointermediate and this is treated to give an isocyanate-ended, low molecular weight polymer by combining the macrointermediate with methylene bis(4-phenylisocyanate). This low molecular weight polymer is then reacted further with h drazine to give a high molecular weight elastomer polymer in accordance with the disclosure of French Patent 1,172,566.
Representative of non-elastomeric binders useful in this invention are polyamides such as polyhexamethylene adipamide, polycaproamide, copolymers of polyhexamethylene adipamide and polycaproamide (preferably an 20 copolymer, respectively), poly-N-methoxy hexamethylene adiparnide and the like. Representative polyesters useful as binders include polyethylene terephthalate, polyethylene isophthalate, copolymers of polyethylene terephthalate and polyethylene isophthalate (preferably an 80/20 copolymer, respectively), poly(hexahydro-p-xylylene terephthalate), etc. Particularly useful urethane binders are the urethanes formed by reacting piperazine and ethylene bis-chloroformate, the polyurethanes of hexamethylene diamine and ethylene bis-chloroformate, etc.
The following examples illustrate the invention. All bonded non-woven fabrics illustrated possess the structural characteristics and physical properties of the products of this invention.
EXAMPLE 1 Using an apparatus assembly essentially as shown in FIGURE 1 and comprising a spinneret adapted to spin two dilferent polymers simultaneously, polyhexamethylene adipamide (40 relative viscosity) and an 80/20 copolymer of polycaproamide and polyhexamethylene adipamide (41 relative viscosity) are spun into filaments at a temperature of about 290 C. The filaments are spun into a quiescent atmosphere, at ambient temperature (25 C.) and relative humidity (70% A copper aspirator jet is located 8 inches below the spinneret to forward the filaments to a receiver. The jet has the following dimensions:
Yarn inlet 16 diameter (top) inches 1%; Filament passageway 15' diameter do Cut-down from yarn inlet to yarn passageway occurs over do /2 Filament passageway 15 length do 27 Air inlet 4 diameter do Angle of air entry 17 degrees 45 The aspirator jet, which is supported in the filament line by insulated means, is supplied with 40 p.s.i.g. air and connected to an 8000 volt source of electrostatic potential (rectifier generator Model No. H-40 available from New Jersey Engineering Company, Kenilworth, New Jersey). The receiver is a 12 x 12 inch solid aluminum plate, manipulated manually and grounded. Filaments are collected into hand sheets by interposing the receiver into the filament line and rotating the same until a uniform sheet of the desired thickness and configuration is obtained.
Stability of the batt produced is enhanced by subsequently heating the sheet to a temperature in the vicinity of 200-220 C. Embossing with pattern during such heating can be employed to provide modifications of surface appearance, handle, drape, etc. Several advantages derive from cospinning, including uniform binder distribution, good control of binder content, good sheet cohesion even prior to heating, and good resistance to delaminating and picking.
A similar effect is obtained by co-jetting as-formed copolymer filaments from a supply package into the filament stream of Example 1 as it leaves the aspirator jet.
Equally well, the jet delivering the binder filaments can be separated from the jet delivering the major fraction of the filaments. In this way, it is possible, and at times desirable, to prepare a composite web in which thin layers of binder filaments are interspersed with thicker layers of non-binder filaments to give a fabric with a decreased tendency toward pickiness and delarnination.
A fabric prepared as described above (with 10% binder fibers) is found to have, after bonding, the following properties:
Fiber crimp level 40-60 c.p.i.
Free fiber length 1.3x
Density Over 0.30 g./cc. Tensile strength 8.0lbs./in./oz./yd. Tear strength 2.0lb's./oz./yd. Drape stiffness 0.9 in.
Ratio TS/DS 27lbs./in.
EXAMPLE 2 Spontaneously elongatable fibers of polyethylene terephthalate are prepared in accordance with the teaching of Belgian Patent 556,145 in the following manner. Polyethylene terephthalate is spun at 295 C. through a spinneret having 27 orifices, each 0.009 inch in diameter, and the resulting filaments are collected into a yarn which is wound up at a speed of 1200 yds/min. The yarn is found to have a denier as-spun of 135, a birefringence of 0.0094 and a crystallinity level which indicates it is substantially amorphous. The yarn is passed from the feed roll to a bath of water maintained at 20 C. to a draw roll, after which it is wound up on a suitable package. The yarn speed at the draw roll is 400 yds./rnin. The draw ratio is 2.80. The birefringence of the drawn yarn is 0.1902. Immediately following the drawing treatment, the drawn yarn is immersed in water at 70 C. for a period of 5 minutes. During this process the yarn shrinks 38.3% of its original length. Following this treatment, the yarn is dried and is then found to be spontaneously elongatable. The spontaneous elongation is tested by immersing a 10 measured length of the yarn in water at C. for 5 minutes. This treatment causes the yarn to increase in length by 9.3% of its original length. The fibers have a modulus of about 20.
In similar preparations, involving variations of crystallinity, draw ratio, and thermal treatment, similar polyester fibers are obtained which exhibit spontaneous elongation amounting to as much as 29%. This yarn is suitable for cutting into staple lengths for further processing as described below in accordance with the teaching of the present invention.
EXAMPLE 3 A dispersion in water of an elastomer terpolymer containing 92% ethyl acrylate, 6% methyl acrylate, and 2% acrylic acid (Rhoplex B-15), 46% solids, is converted to highly stable fibrids as follows.
To a quantity of the dispersion containing parts of elastomer is added 5 parts of diepoxide resin, a monomeric bis-glycidyl ether of diphenylol propane having an epoxy equivalent of 175-210 (Epon 828, sold by Shell Chemical Corporation), and 5 parts of a butylated melamine formaldehyde resin containing one part melamine to 4-5 parts formaldehyde (Uformite MM-46, sold by Rohm and Haas Company), and 5 parts of titanium dioxide pigment.
The compounded mixture is converted to fibrids by shear precipitating techniques, that is, by adding the resin blend to a Waring Blender containing a 5% solution of sodium sulfate in hot water with 0.01% of an organic quaternary ammonium salt as wetting agent. The Blender is operated at full speed during the addition. The resulting fibrids are used in the form of the slurry as prepared.
A slurry of 3 parts of staple fibers (A inch long, 3 denier) prepared as in Example 2 and having a spontaneous elongation of 10% when treated wtih boiling water, and 2 parts of fibrids in 10,000 parts of Water is prepared and a waiterleaf is formed in. the manner already described. The sheet is removed from the screen, dried, placed between a cotton cloth sheet and a 12-mesh wire screen, and dried at C. for 3 minutes. The dried sheet is then placed between SO-rnesh screens and embossed and bonded at 205 C. for one minute at 200 psi. The sheet is further cured by exposing to air at C. for 5 minutes. The sheet is washed and tumble dried before testing. The fabric contain 40% elastomeric binder which has a modulus of 0.01 g./den. before curing and 0.015 after curing. It has a tensile strength of 5.9 lbs./in./oz../yd. a basis weight of 3.5 oZ./yd. a drape stiffness of 0.75 inch, and a wet tensile strength of 4.5 lbs./in./oZ./yd. Under microscopic examination, it is seen that the individual fibers are highly crimped and convoluted, having 60-80 c.p.i., and a free-fiber length of about 1.6x between adjacent bonding sites. The fabric is found to have good strength retention when exposed rto dry-cleaning solvents. The embossing treatment produces a fabric resembling ()xford cloth in appearance, with excellent whiteness, good retention of whiteness, medium porosity and good handle.
EXAMPLE 4 An aqueous suspension of self-elongatable fibers prepared as in Example 2 and having a spontaineous elongation of 10% upon immersion in boiling water is prepared by combining 10,000 pants of water with 3 parts of inch long, 3 denier per filament of these selfel-ongatable polyester fibers thoroughly wetted with a 5% solution of Alkanol HC surface active agent (a polyethylene oxide ethe-r fatty alcohol). To this suspension of fibers is added a sutfieient portion of an elastomer fibrid slurry prepared from a 45/55 butadiene-styrene e lasitome- LO provide 2.0 parts of the compounded fibrids in suspension form. The butadiene-styrene elastorner has a modulus of 0.008 gram per denier. This fiber-binder suspension is then poured into a headbox of a sheet mold, and therefrom a waterleaf is deposited onto an 8" x 8" lOO-mesh screen under espirator vacuum. The excess water is squeezed from the waterleaf by placing it while still on a IOU-mesh screen between absorbent cloths and rolling it with a steel rolling pin. The waterleaf is then lus of 3 grams per denier. The web, as formed, is then placed between two SO-mesh screens, and pressed at 175 C. for 1 /2 minutes at 5000 p.s.i.
The resulting sheet is so'fit, drapable, clothlike and withrenroved from the screen and placed between 50-mesh 5 out any papery quality. Due to the embossing effect of screens, which in turn are placed between sheets of pulp the screens, it is like a woven broadcloth in appearance. board and dried in a press at 150 C. and 95 lbs./ sq. in. The sheet is found by chemical analysis to contain 3.9% pressure for minutes. Following this pressing trcatof the binder component. The basis weight is 3.1 oz./yd. ment, the non-woven sheet is obtained in the form of a the sheet density is 0.01 lb./in. and the drape stiffness is fabric having a woven texture due to the imprint of the 1 1.0 inch. The sheet is 18 mils thick and has a tensile 100-mesl1 screen and the 50-mesh screen which had bee strength of 6.26 lbs./in./oz./yd. The ratio of tensile in contact with it during pressing. The free fiber length strength to drape stillness is approximately 19 lbs. is about 1.5x (an average of 1.5 times the straight line A similar sheet, wtih a fibrid binder content of 3.6%, distance between bond points), crimp level is about 60 is pressed for 45 seconds at 50 p.s.i. to give a sheet with c.p.i., and fabric density is 0.4 g./cc. The sheet is tested a drape stiffness of 0.6 inch. Other soft drapade sheets for physical properties and found to have a tensile strength are prepared in similar experiments with from 4% to 23% of 3.12 lbs./in./oz./sq. yd. and a tongue tear strength of binder content. Still other sheets are prepared by bonding 1.01 lbs./oz./sq. yd. The drape stillness in inches of the effected by impregnation with a dispersion of an elastosheet is 0.796. It is observed that washing this sheet in meric resin. All of these sheets share the desirable physia synthetic detergent increases its strength as follows: cal properties already indicated. tensile strength of 5.27 lbs./in./oz./sq. yd.; tongue tear in this example the aspirator jet forwarding the yarn strength of 1.16 lbs./oz./sq.. yd. The dra e stiffness is was also used to charge the filaments and thereby maindecreased slightly to 0.722 inch. rain the filaments separated from each other between the Following the same procedure, substituting a hard aspirator jet and the receiver plate. binder for the elastomeric binder, excellent fabrics are 25 Examples 6 through 12 set forth in Table HI show obtained containing 7.5% copolyester fibrid binder the comparison of non-woven fabrics of this invention ethylene isophthalate and 20% ethylene terephthalate) with conventional wove fabrics. The non-woven fabrics and 92.5% of the fibers of Example 3. of Examples 8 and 9 were prepared by admixing 3 parts EXAMPLE 5 0t: staple fibers with 8000 parts of water with vigorous 30 stirring 1n the presence of a small amount of an alcohol Poly(hexanrethylene adi am'ide) having a relative visas wetting agent. To the fiber suspension thus formed is cosity of 41 is spun through a 59-hole spinneret, each added an aqueous slurry containing 2 parts of the fibrid hole being 0.007 inch in diameter. The spinnerct delivers indicated. This stock is poured into a head box of a 14 grams of polymer per minute. The yarn is led 011- sheet mold and a waterleaf deposited on an 8 x 8 100- rectly a Pneumatic l PP Y 3 inches below mesh screen. The screen with the deposited waterleaf is the spinneret f p g With P T s removed from the sheet mold and placed between abl forwards the yarn and 911 the Same timfi alllemletfis. sorbent cloths and rolled with a steel rolling pin to re oreints, and qucnches it and directs it onto a fiat receiver m excess t Tu h t i th dried bgtween plate which is moved to permit the build-up of a web of screens at 130 C. and lbs/sq. in. pressure for 10 uniform thickness- 40 minutes. The screens give a pattern to the resulting non- During and after the course or impact of the yarn on woven f b i i il t a Woven f b i til; feceiivfiy the filamwis highly clfimpfid The non-woven fabric of Example 10 was prepared in least c.p.i.). As the filaments are accelerated toward a manner i il t th t f E l 3 d 9 b t i the y are Sprayed Wfih fiulfidl'ied cflpolyamidfl the absence of elastomer. The waterleaf was then wetted fibrids consisting of an 80/20 copolymer of polyhexa- 45 with a 46% aqueous dispersion f Rhoplex B 15 d methylene adipam-ide and polycaproamide which are the treated waterleaf was then cured at 130 C. and flocked onto the thrcadline. This copolymcr has a modu- 50 lbs/sq. in. pressure for 10 minutes.
TABLE III Comparison of Woven Fabr cs With Non-Woven Fabrics of This Invention Fabric Properties Ex. No. Fabric Type and Composition Thick- Tensile Drape Free Tonsile/ Fiber Appearance Basis Wt. noss Density Strength Stifinc-ss Fiber Drape Crimp (on/yd?) (mils) cm. (g./cm. (1bs./in./ (inches) Length (lbs) (c.p.i.)
Woven Cotton Broadcloth." 3.80 .025 0. 59 12. 5 0. 01 45 Typical woven fabric. Woven Wool Flannel 8.0 .0865 0.37 3. 5 0. 62 36 D0. Non-Woven Fibrid bonded: 3. 5 .036 0.40 5. 5 0.75 1. 4X 26 Similarto \vovcnfabric; 60% 8.15. Fiber A 40% good covering power. Fibrid B. 9 Non-woven Fibrid bonded: 3. 5 .033 0.42 4. 2 0.75 1. 25X 20 40 Like woven fabric.
60% S.E. Fiber 0 40% Fibrid B. 10 Non-woven resin bonded: 60% 3. 6 036 0.41 6. 7 0. 1. 7X 30 More porous than non- S.E. Fiber A; 40% Rhoplcx woven fibrid-bonded 13-15 d resin dispersion. fabric of Exs. 8 or 9. 11 Commercial Wool Felt 5. 5 .099 0.18 7. 5 1. 28 32 Typical felt; bulky and stiff. 12 C(fmnscrcial Non-woven Pcl- 2. 6 066 0. 16 3. 4 1. 04 5 Very stifi and bulky.
on 20. e
a S.E. Fiber ASclf-elongatable polyester fibers of Example 2 (Mi=10).
shear precipitation coagulation (Mi=0.7)
ethyl acrylate, 6% methyl acrylato, and 2% acrylic acid, formed by c Fiber OSelf-el0ngatablo polyhrnitlc fibers (poly(pxylylenc azeleamidc)). d Elastomer added as a dispersion in water, sold as Rhoplex 13-15 by Robin and Haas 00., used as received. a A non-woven 66-nylon fiber fabric bonded with a synthetic polymer binder.
EXAMPLE 13 Fibers of polyethylene terephthalate are. melt spun from a 30-hole spinneret, having a hole diameter of 7 mils, at a rate of 10 g./min. The spinning technique employed involves the principles shown in FIGURE 1. The fresh- 1y spun filaments are passed over a chromic oxide bar to give an induced electrical charge on the filaments. An air jet is employed to attenuate and forward the filaments, advance the filaments to a collector, and permit a random laydown of fibers. There is obtained an unbonded non-woven batt having a weight of 0.5 o-z./yd. The arrangement of charge-inducing contact bars, spinning speed and jet velocity gives a web which, when treated in the manner described below, shrinks in area because of the shrinkage of the individual filaments combined with the crimping of the filaments. The treatment employed is that described in more detail in Belgian Patent 566,145
The batt of unbonded fibers is consolidated by placing it between wire screens and pressing at 100 p.s.i. at 50 C. The web is then removed from the screens, wetted with water containing a synthetic wetting agent, and placed on a glass fabric which has been coated with polytetr-afiuoroethylene resin. The web is exposed to steam at atmospheric pressure for ten seconds, which causes fiber shrinkage and fiber crimping leading to an area reduction of 75% of the web.
This preshrunk web is then bonded, employing an aqueous dispersion. of the terpolymer resin material of Example 3. Resin impregnation of this web gives a bonded sheet having a binder content of 40% by weight. The bonded sheet is then heat-treated to effect elongation of the filaments and complete the resin-bonding and crosslinking operations simultaneously. This is done by placing the webbetween 50 mesh wire screens and heating it in a pressat 210 C. at 200 p.s.i. pressure for one minute. Following this treatment, the sheet is cured in an oven for five minutes at 175 C. and is then washed and dried.
The resulting non-woven fabric is a soft, drapable material having a pleasant feel and a texture similar to that of a woven fabric of the same material. The polyester fibers hawe a crimp of 80 or more crimps per inch and the free fiber length is approximately 1.6. The modulus of the binder is 0.015 gram/denier. The polyester filaments have a modulus of approximately 20 grams/ denier, and the denier of these filaments is approximately 1.4. The fabic has a base weight of 3.2 oz./yd., a tensile strength of 7.5 lbs./in./oZ./yd. and a tongue tear strength of 1.4 lbs./o-z./yd. The sheet density is 0.37 gram/cm. and the drape stiffness is 0.69 inch. The sheet has a ratio of tensile strength to drape stiffness of 20.9.
A similar fabric is prepared. by .co-spinning with the fibers a copolymer binder of 80% ethylene terephthalate and 20% ethylene isophthalate.
EXAMPLE 14 A non-woven web prepared as in Example 1 and comprising 95.3% polyhexamethylene adipamide fibers and 4.7% of an 80/20 copolymer of 6/66 nylon fiber, said web weighing 14 oz./ sq. yd. at a thickness of 35 mils, is impregnated with a solution of a polymer to bind the fibers at spaced points and impart strength and integrity to the structure. The polymer is prepared by reacting a poly(tetramethylene ether) glycol of approximately 1000 molecular weight with tolylene-2,4-diisocyanate to give a glycol-terminated macrointermediate, and this is treated to give an isocyanate-ended low molecular weight polymer by combining the macrointermediate with methylene bis- (4-phenylisocyana'te). This low molecular weight polymer is then reacted further with hydrazine to give a high molecular weight elastomer polymer in accordance with the teaching of French Patent 1,172,566. This synthetic elastomer is dissolved in dimethylformamide to give a final solids content of 15%. The nylon web is impregnated by soaking in this solution for 5 minutes to insure adequate pickup of the binder. Excess binder is removed by passing the soaked structure through squeeze rolls followed immediately by immersing the web in a water bath to coamilate the polymer. Dimethylformamide being completely miscible in water is leached out of the structure by continuous immersion in the coagulation tank which held a volume of water substantially larger than the quantity of dimethylforma-mide to be removed from the web.
Coagulation, rather than solvent evaporation, is favored as a means of fixing the binder in the non-woven substrate because of a high degree of porosity obtained by the former procedure in contrast to the largely impermeable film produced by solvent evaporation.
The coagulated and leached substrate is dried at about C. in a slack condition. The product is soft and drapable This product is then buffed with abrasive paper to produce a suede surface. The resulting product is soft and drapable with a suede-like surface texture which renders it SUllLElbllC as an apparel fabric for childrens and womens skirts, mens jackets, etc. T o produce a porous leather-like material suitable for shoe uppers, a coating is applied in accordance with the teachings of copending application Serial No. 723,669 filed March 25, 1958, by E. K. Holden, now abandoned. The coated fabric is dried at about '100 C. and then dyed a dark brown and again dried. A leather-like grain is imprinted on the surface of the dyed fabric by preheating the material at 70 C. for 10 minutes and then embossing with a grained flat plate at 70 C. at 700 p.s.i. for 5 seconds.
EXAMPLE 15 Highly crimped filaments of nylon 66 yarn are prepared by passing conventional nylon yarn through a fiuid torque jet. Just prior to its entrance into the jet, the yarn is passed over a heated metal plate (about 250 C.). The heated filaments are twisted and crimped by the action of the jet, which also cools, sets, and untwists the filaments below the plate. The result is a continuous filament yarn with 40 to 60 crimps per inch.
A quantity of these filaments is cut by hand into approximately /s lengths (relaxed). Two parts of the short lengths of fiber are dispersed in approximately 1000 parts of water with 10 parts of carboxymethyl cellulose and one part of a quaternary alkyl ammonium salt as wetting agent to assist in the dispersion. To the dispersion is added an equal amount of fibrids formed from the syn thetic elastomer of Example 14.
A hand-sheet is prepared from this dispersion, and the waterleaf is found to be soft, stretchable, drapable, and similar to a soft flannel in handle. When the sheet is pressed at C. at 400 p.s.i. pressure for 10 seconds, it
becomes stronger and firmer, but still soft and drapable.
The fibers are found to have 40 to 50 crimps per inch in both the unpressed and the pressed sheets. The density of the unpressed sheet is about 0.30 g./cc., while that of the pressed sheet is 0.61 g./cc.
The non-woven fabrics of this. invention are characterized by a high degree of drapabili-ty and flexibility, and a desirable level of loftiness, and handle. Because of these and other properties, they are well suited to end uses which have heretofore employed woven fabrics of varying weights and weaves. Among such uses may be listed apparel; draperies; upholstery materials; household furnishings, such as table cloths, napkins, and bed linens; shaped articles, such as gloves, heat coverings. In the field of apparel fabrics, the fabrics of the present invention are specifically well suited to work and service clothing, sports wear, outer wear, bathing suits, shirts, and the like. Other fabric utilities include foundations for leather-like laminates, backings for vinyl-coated upholstery, and other fabrics, automobile and airplane headliners, fiiter cloths and other industrial felts. These fabrics are also suitable with proper coatings or surface treatment for use as fuel pump diaphragms, hosing, flexible couplings, and air bel- 15 lows for use in instrumentation work and decorative covers for desk equipment, radios, ash trays, cigarette boxes, and the like.
Because of the thermoplastic nature of the fibrous materials employed in these products, it is possible and desirable under certain circumstances to post-form the sheet products of the present invention obtaining thereby molded articles possessing specific and desirable three-dimensional configurations. In general, it is preferred that when fibrid binders are used, the products of the present invention be heat-treated to a degree sufiicient to fuse at least a portion of the fibrid binders. However, non-fused products are also of interest and have found applications in a number of the utilities indicated above.
As had already been indicated, the non-woven fabrics of the present invention are embossable and can be obtained with any of a wide variety of surface patterns which may be impressed upon the fabric during the pressing or fusing process. Such embossed configurations not only supply decorative and attractive appearance, but can be used to control the physical properties of the fabric. Thus, an embossing pattern consisting of a number of parallel fine lines in one direction only produces a fabric which has a greater flexibility in one direction than in the other direction. Embossing with a cross-hatched type of pattern of fine lines increases the stiffness of the fabric in both directions. Other embossing techniques can be used to alter the handle and feel of the fabric and also to control the receptivity of the fabric to printing, dyeing, and other coloring post-treatments. During the embossing process the bulk of the non-woven fabric can be controlled to any desired degree, and compression can be introduced to lead to a more compact structure, if this is desired. Furthermore, it is not necessary that only a single embossing step be introduced. If desired, it is possible to emboss upon the non-Woven fabric an overall textured pattern by the use of wire screens as already shown. Thereafter, this fabric can be further modified by a second embossing treatment employing platens, calenders, intaglio rolls, or the like.
Fabrics of the present invention can be buffed to expose surfaces which are densely populated with uniformly distributed fiber ends of equal length. Such buffed surfaces are very attractive and resemble to a surprising degree in hand suede leather and other similar products.
The products of the present invention have a number of advantages in comparison to previously known nonwoven fabrics. In comparison with ordinary and conventional cotton or wool felts, the present materials show equal or higher strength, greater dimensional stability, and greater flexibility. In comparison with non-woven sheet products from ordinary synthetic fiber staple bonded with resin materials, the non-woven fabrics of the present invention have a much softer handle, greater strength and flexibility, and a better dyeability and printability. In addition, the fabrics of the present invention show an excellent degree of post-formability, high elongation and reversible deformation, excellent wash-wear characteristics, outstanding tensile and stitch strength, and, as has already been indicated, a degree of drapability and controllable handle which has not hitherto been achieved in non-Woven fabrics in the art.
EXAMPLE By repeating the procedure of Example 1 to produce a web of amorphous poly(ethylene terephthalate) filaments and then relaxing or shrinking the Web in a stepwise (controlled) manner, that is, by partially shrinking,
1% then embossing followed by further shrinking, there is produced a web in which the filaments each possess a micro-crimp of some 400-500 crimps per inch superimposed upon the conventional crimp. The resulting fabric is very highly drapable.
The fibers useful in this invention have a bending stiffness which is proportional to the product of the initial modulus (Mi) of the fiber and the 3/2 power of the fiber denier. For purposes of this invention, the product M1 X (1 is between 1 and 1000 and preferably between 5 and 250.
The claimed invention:
1. A nonwoven fabric comprising crimped synthetic organic fibers, said fibers having at least 30 crimps per inch of unextended length, the fabric containing between about 3% and about by weight of a synthetic organic polymer binder which is dispersed throughout the fabric, and bonds the fibers so that the average free fiber length between bond points is at least 1.25 times the average straight line distance between these bond points, the binder having an initial tensile modulus (Mi) of between about 0.002 and about 25 grams per denier and being present in an amount such that Percent bindorXi/ZVH (binder) 40 the fabric having a density between about 0.28 and about 0.7 g./cc., a drape stiffness of less than about 1.0 inch, a ratio of tensile strength to drape stiffness of at least 12.0 lbs. and a sonic velocity transmission at 6% elongation of the fabric, equal to at least 1.3 times its value at 0% elongation.
2. The fabric of claim 1 in which the synthetic organic.
fibers are continuous filaments.
3. The fabric of claim 1 in which the synthetic organic fibers are staple fibers.
4. The fabric of claim 2 in which the fibers are polyamide fibers.
5. The fabric of claim 2 in which the fibers are polyester fibers.
6. The fabric of claim 5 in which the polyester is polyethylene terephthalate.
7. The fabric of claim 6 in which the binder is a copolyester of ethylene isophthalate and ethylene terephthalate.
8. The fabric of claim 6 in which the binder is an elastomeric polymer.
9. The fabric of claim 3 in which the fibers are spontaneously elongatable fibers of a condensation polymer.
10. The fabric of claim 3 in which the fibers are composed of polyethylene terephthalate.
11. The fabric of claim 10 in which the binder is an elastomeric polymer.
12. The fabric of claim 11 in which the binder is an acrylate ester elastomeric binder.
References Cited in the file of this patent UNITED STATES PATENTS 705,691 Morton July 29, 1902 2,197,896 Miles Apr. 23, 1940 2,336,745 Manning Dec. 14, 1943 2,385,873 Melton Oct. 2, 1945 2,416,390 Hitt Feb. 25, 1947 2,465,996 Bloch Apr. 5, 1949 2,676,128 Piccard Apr. 24, 1954 2,810,426 Till et al. Oct. 22, 1957 UNITED STATE 5 PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,117,055
January 7, 1964 EsperanzaGuandique et a1.
It is hereby certified that error a ent requiring correction and ppears in the above numbered patthat the sa corrected below.
id Letters Patent should read as after "edge" insert divided by two Signed and sealed this 26th day of October 1965.
ERNEST W. SWIDER nesting Officer EDWARD. J. BRENNER Commissioner of Patents UNITED STA TE 5 PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,117,055
January 7, 1964 d that error a ent requiring correction a ppears in the above numbered patnd that the said Letters corrected below Patent should read as (SEAL) west:
ERNEST W. SWIDER EDWARD J. BRENNER nesting Officer Commissioner of Patents