US2238098A - Fabric - Google Patents

Description

April 1941' H. BRADSHAW 2,238,098

FABRIC Filed July 28, 1938 Pa Waiya Y/zrezzdr P ml; (A1 \.L-' 1! Ag A Ground M1170 Threads Ground Weft Threads" Hamdfimn rsha/u) INVENTOR.

ATTORNEY Patented Apr. l5, 1941 UNITED STATES PATENT OFFICE .FABBIC Hamilton Bradshaw, Wilmington, DeL, asslgnor to E. I. du Pont de Nemours 8; Company,

Wil-

mington, Del., a corporation of Delaware Application July 2a, 1938, Serial No. 221,732

2 Claims. (Cl. 139-391) in damp weather is anotherdisadvantage fre- This invention relates to the production of pile fabrics, such as velvets, transparent velvets, plushes, mohairs, carpets, fur-like fabrics and the like, from synthetic linear condensation polyamides.

Pile fabrics comprise a large part of total textile production since they are pecularily suitable for a large variety of purposes. There are many types of pile fabrics adapted to different uses. These are produced by various constructions and combinations of pile elements-and ground fabrics, respectively. These constructions and combinations of the same or different textile filaments will be described more fully hereinafter, but regardless of the type of pile fabric, there are certain common properties desired of all.

One of the most important of these is that the pile be permanently crush resistant. Although the term "crush resistant" is widely used in the art, it should not be interpreted literally. The most desirable pile is not one which resists deformation but rather one which is easily deformed and returns readily to its original position when the load is removed. In other words, what is really desired is recovery from crushing or true elasticity. Any attempts to prevent permanent deformation by using coarser piles or by stiffening them are therefore not desirable since they detract from the attractiveness of the hand as well as the utility of the fabric.

Although wool, silk, mohair and other natural products are fairly satisfactory as pile elements within certain limits of load, temperature and humidity, their utility is limited. Synthetic filaments such as regenerated cellulose rayon have been used as the pile in pile fabrics, for example. in transparent velvets, but its crush resistance is so poor it has been very desirable if not necessary to subject it to certain chemical treatments to improve its properties. These chemical treatments may result in a stiffening of the pile and unless carefully controlled, embrittle it, and for this reason they are disadvantageous. The property of crush resistance should be permanent and should remain constant under all conditions of humidity and temperature.

It has always been necessary to produce certain types of pile fabrics such as plushes, mo-

hairs, etc., using wool. The effect of the attack F of moths on these fabrics constitutes a grave problem and much expense is incurred in special mothproofing treatments. This same diiliculty is also experienced with natural furs. The development of musty odors from some pile fabrics quently experienced.

Heretofore certain, problems were encountered in the actual production of pile fabrics. Among these was the difficulty in obtaining a pile of uniform length. Piles of uniform length were obtained only by repeated shearings accompanied by steaming and brushing operations, the steam rendering the pile more plastic and permitting its rearrangement by brushing. These operations are expensive and represent a large share of the total cost of the finished fabrics. Likewise, these repeated steamings tend to reduce the resiliency of the pile.

Another difficulty previously experienced was non-uniform dyeing. This takes two forms: that of ordinary dyeing differences common to many textiles, especially those made from natural materials; and another more serious problem sometimes referred to as greighing off. This was experienced in pile fabrics with a pile of high denier and is characterized by difference in penetration of the dye into the pile elements, with accompanying differences in depth of color across the cross-sectional area. This difficulty is often experienced with mohair.

While the pile elements of pile fabrics have been discussed, the choice of the ground fabric is also very important. Natural silk has been used almost exclusively as the ground warp for the production of pile fabrics for dress goods such as transparent velvet. The use of silk for this purpose has presented many dimculties. To obtain the desired sheerness, strength, hand, elasticity, etc., it is necessary to use the best quality silk. Since silk is a natural product, it is dependent upon the variations of supply, world conditions, etc., and the problem is further complicated by this necessity of using only the best grade of silk for this purpose. The use of silk as the ground fabric presents a serious dimculty peculiar to silk itself. Silk has a closely adhering coating of a gum called sericin. This gum aids materially in the manufacturing operation, preventing damage during weaving. After a pile fabric has been prepared using silk as the ground warp, it is necessary to remove this sericin. This is commonly called a boll-off treatment, and is quite severe. This finishing process interferes with the appearance and quality of the pile. This is especially serious with a cellulose derivative rayon pile, since the treatment necessary to remove the sericin saponifies the cellulose derivative pile and seriously damages it, so that it is of little use. This finishing treatment is also very expensive and represents an appreciable part of the total cost of the fabric.

It has long been desired to provide the art with a high grade of pile fabrics, especially dress fabrics such as transparent velvet, made entirely of synthetic filaments. Although regenerated cellulose rayon has been used as the pile element, it has been very desirable, if not necessary, to treat the pile to improve crush resistance, as indicated above. Since this treatment must be selective to the pile as distinguished from the ground fabric, the choice of ground fabrics has, therefore, been decidedly limited.

It is, therefore, an object of this invention to produce new and useful pile fabrics.

It is another object to prepare a pile fabric having a high degree of permanent crush resistance without stiffening of the pile.

Another object of this invention is to prepare a high grade of pile fabric which is constructed entirely from synthetic filaments.

The objects of this invention are accomplished, in general, by using synthetic linear condensation polyamide filaments for the construction of pile fabrics. The synthetic linear condensation polyamide filaments serve exceedingly well for use in the pile threads, the ground warp threads or the filling threads of pile fabrics. As a consequence the entire pile fabric may be constructed of these synthetic filaments with excellent results.

The accompanying drawing illustrates, in a single figure, a pile fabric constructed in accordance with the present invention.

Referring to the drawing the pile fabric i11ustrated is comprised of ground warp threads, ground weft threads and pile warp threads, as shown by legends in the drawing. Preferably, the various threads of the pile fabric are all composed of synthetic linear condensation polyamide filaments.

Fiber-forming synthetic linear condensation polyamides and fibers produced therefrom are described in U. S. Patents Nos. 2,071,250, 2,071,- 251, and 2,071,253. The term synthetic linear condensation polyamides includes two types of polymers-those obtainable from monoaminomonocarboxylic acids and those obtainable from the reaction of suitable diamines and dibasic carboxylic acids. The diamine-dibasic acid polymers are described in greater detail in the U. S. patent application of W. H. Carothers, Serial No. 136,031, filed April 9, 1937. The filaments which are preferable to use are made from polyhexamethylene adipamide, the polymer derived from hexamethylenediamine and adipic acid. While in some modifications of this invention, unoriented synthetic polyamide filaments may be used, it is preferable in most cases to use the oriented synthetic polyamide fibers.

The methods of preparing pile fabrics are well developed. One of the best known makes use of a double shuttle loom which uses two sets of ground warp and filling yarns to weave two backings or ground fabrics which are held together by a pile warp which is common to both backing fabrics. Through the use of a cutting apparatus, the fabric is cut on the loom in two separate pieces. Many velvets and plushes are produced in this manner.

In another process, an extra set of warp threads are formed into loops by passing them over wires whose upper edges are sharp, or which have a cutting attachment on one end. The loops are fastened in while the cloth is being woven and are cut as the wires are removed. Uncut velvets and plushes may be produced in a similar manner, using wires which do not out the loops.

In certain types of pile fabrics, the pile comes from an extra filler thread mechanically projected from the body of the cloth at regular intervals to form loops or fioats. After weaving, these are cut and brushed up to form the pile. Materials such as corduroy, velveteen, etc., are made in this manner. An uncut pile (known as terry weave) is found in turkish toweling and in some upholstery fabric. Another example of an uncut pile is a frieze.

Further types of pile fabrics and artificial furs are prepared by knitting or weaving pile elements consisting of short, loose fibers in with a base strand such'as a chenille. Fibers may also be sewed on a prepared backing, or attached by means of adhesives.

J. B. Miles, Jr., in his copending application, Serial No. 125,941, filed February 15, 1937, discloses that these linear polyamide fiberstend to become set in the condition or shape in which they are exposed to steam. Hot water, hot alcohols, e. g., methanol and ethanol, hot aniline, or other non-solvent swelling agents also have a similar effect. To achieve a more crushproof and satisfactory pile, it has been found that the polyamide fibers should be set when in the condition or position ultimately desired. To that end, fibers will preferably be employed which have not previously been set, since they can be reset only by a more rigorous treatment.

While similar treatments have previously been applied to pile fabrics made from other materials followed by brushing and other operations, the effect of the steam has been temporary and any setting action has been accomplished only by the process of drying out. As already indicated, however, the most satisfactory fabrics are obtained by setting a polyamide pile in a position ultimately desired by treatment with steam or other agents having a setting action on the polyamide. This treatment sets the pile in a more or less permanent shape, to which it recovers after deformation. The setting treatment, therefore, improves the crush resistance of the pile and is of a permanent nature. Likewise, such a treatment applied to pile fabrics comprising synthetic polyamide fibers as the ground fabric renders them, by virtue of the same setting action, substantially creaseproof. Similarly, when this steam treatment is applied to pile fabrics comprising both the pile element and ground fabric of synthetic polyamide fibers, the fabric is rendered creaseproof and crushproof during the same treatment.

The following examples are illustrative, but are not to be considered as limitative of the invention:

Example I A transparent velvet was constructed using 35 denier filament 10 turn 8". twist dull yarn of oriented polyhexamethylene adipamide in the ground warp and denier 10 filament turn S twist yarn of oriented polyhexamethylene adipamide in the ground filling. The pile warp was made from 100 denier filament 4 turn bright yarn of oriented polyhexamethylene adipamide. The yarns used in the ground warp and filling were treated prior to coning for one hour with air 76.6 C. dry bulb, 71.2 C. wet bulb, which condition reduced the llveliness of the twist sufficiently to permit subsequent handling. The

pile warp yarn was not subjected to this treatment. The fabric was woven in the usual manner on the double shuttle looms, cut and subjected to the usual dyeing, trimming and brushing operations. As the final treatment when the pile had been brushed to a straight condition, the fabric was held on a tentering frame, exposed to the action of saturated steam at atmospheric pressure for minutes, and subsequently dried with hot air. Under these conditions, it was found that the resulting fabric had a very satisfactory appearance and texture and that it was permanently resistant to crushing.

Example II An upholstery fabric comparable to a natural mohair was constructed using warp yarn of 24/2 cotton, with 15 turns per inch in the ply. The filling yarn was 32/2 cotton, with turns per inch in the ply. The pile yarn was 740 denier 80 filament 7 turn oriented polyhexamethylene adipamide. This fabric was woven in the usual manner on a double shuttle loom, but an attachment was added to the loom in front of the cutting mechanism, so that the freshly woven fabric could be subjected to the action of saturated steam at atmospheric pressure for 10 minutes. After steam treatment, the fabric was subjected to the normal cutting operation, splitting the double fabric into its two component fabrics. The appearance of the pile of these fabrics was very satisfactory and the cutting was so even that it was not necessary to re-shear in order to obtain a uniform pile. Likewise, it was found that the pile had dyed very uniformly. The resulting fabric was remarkable for its resistance to crushing, even at high relative humidities, which are frequently encountered in using the fabric as automobile upholstery. The crush resistance of the polyamide pile fabric at 50% R. H. was comparable to that of a mohair upholstery fabric and at 98% R. H. it was greatly superior to the mohair fabric.

Example III A transparent velvet was constructed using denier 10 filament 10 turn S twist dull oriented polyhexamethylene adipamide yarn in the ground warp and 35 denier 10 filament turn 8" twist oriented polyhexamethylene adipamide yarn in the ground filling. The pile warp was 100 denier filament 4 turn regenerated cellulose yarn produced by the viscose process. The yarn used in the ground warp and filling was treated prior to coning in a manner similar to that described in Example I to remove the liveliness of the twist. The fabric was woven; cut, and subjected to the usual dyeing, trimming and brushing operations,

after which it was subjected to a formaldehyde treatment, as disclosed in Heckert U. S. No.

2,080,043 to render the pile crushproof. The re'-- sultant fabric was very strong, superior in strength to a silk backed-fabric and the pile was more attractive since it was not necessary to boil off to remove sericin.

Example IV The pile because the cellulose acetate pile had not been subjected to a boil-off treatment.

Example V An filament 200 denier yarn prepared from oriented polyhexamethylene adipamide fibers was wound on a fiat metal guide (Singercraft attachment), having a slit at one side of the center and a cutting attachment at the end. The yarn was sewed to a cotton backing, the seam being through the slit in the guide. Upon completion of the sewing, the metal guide was withdrawn, cutting the row having the larger loop. Consecutive parallel rows of loops, spaced from V; inch to inch apart, were sewed on cotton in the same manner, so that the closely overlapping rows of pile gave a thatched, fur-like effect. The resulting pile fabric was then stretched on a tentering frame, the rows of pile carefully arranged in the ultimately desired position. A screen was then placed on the pile surface to maintain the pile in this position, the fabric treated with boiling water for ten minutes. The screen was then removed, and the fabric dried in air at 76.6" C. The resulting fabric had a very attractive pile, arranged in the desired configuration, and was permanently very resistant to disarrangement.

In the production of pile fabrics with yarns composed of synthetic linear condensation polyamides a wide range of filament and thread sizes can be employed to serve the various objects above set forth. The pile warp threads may have a denier of from 50 to 2000 depending upon whether they are to be used for sheer transparent velvet or for upholstery fabrics or rugs. The filaments of such pile threads may vary from 0.2 denier to 6 denier per filament in transparent velvet to 10 to 20 denier per filament in rug constructions. Ground warp and filling yarns will vary from 25 denier 170,300 denier and these threads will be composed of filaments having a denier of 0.5 to 10, depending upon the particular fabric construction.

The number of synthetic linear condensation polyamide yarns per inch used in the various fabric constructions will also vary greatly. In transparent velvet the pile warp yarns may be spaced closely together so as to have from 25-to '75 yarns per inch; on the other hand, in the production of imitation furs the pile yarns may be spaced from each other so as to have only 4 to 20 yarns per inch. Ground warp and filling threads will vary from 20 to threads or pics per inch depending upon the type of fabric construction.

In the preparation of fur-like materials, it is sometimes desirable to use fibers of more than one size and length, the long fibers being of a large denier and the shorter ones being very fine and soft to the touch. Furthermore, it is sometimes desirable to use tapered filaments, thus more closely simulating natural furs. Likewise, it is desirable in many fur-like materials to have the pile recline in one direction, as in a natural pelt. This is especially important when the fabric is to be used in outer garments to shed water. This condition can be accomplished by arranging the pile in a desired way and setting it.

Crimped or curly forms of the fiber may be used in essentially the same manneras a straight fiber. This is of special advantage in giving a soft, resilient, fur-like pile. A novel fabric can be made by completing the crimping process on the pile filaments after incorporation in the fabric, This can be done by using as the pile warp spontaneously crimpable polyamide filaments prepared by the process of copending application of Hardy and Miles, Serial No. 183,922, filed January 7, 1938.

- spontaneously crimpable filaments in the pile warp, the crimpable filaments are held under tension by the fabric structure until the pile is cut. Before cutting the pile, therefore, it is necessary to wet the pile unless it is already wet. After cutting, the fabric is dried, whereupon the pile crimps spontaneously. The crimp may be rendered more permanent by steam treatment which also improves the crush resistance of the pile. The curly pile has unusually good covering power.

Unoriented synthetic polyamide filaments may also be used as the pile elements. If desired, these pile elements may be subjected to cold drawing after being woven into a pile fabric. Novelty effects may be obtained by drawing only a part of the pile elements thus producing piles comprising intermingled short and long filaments of different or the same cross-section. Such a process is valuable in the production of artificial furs.

The use of delustered fibers, colored fibers, and fibers containing plasticizers or waterproofing agents is within the scope of my invention. Likewise, for certain purposes, finish, size or other materials may be applied to the fibers at some time prior to, during, or after weaving. Waterproofing compositions or compositions which will cause the fabrics to shed water may be applied. Such treatments are especially valuable for those fabrics exposed to the elements as in natural furs.

I have not specified whether I prefer to use shrunk or unshrunk filaments for the pile. I have found that I can use both successfully. For certain purposes, shrunk yarn may be desirable, in which case I prefer to subject the yarn to a shrinkage treatment which will not set it relative to the setting in the final form in the fabric. This can conveniently be accomplished by exposure to dry heat in a relaxed condition for a short period at a temperature of 140 C.

While it would be expected that synthetic polyamide filaments which have been shrunk would be preferred for use in the ground fabric since the shrinkage of the fabric during subsequent treatments would be prevented, this is not always the case. These synthetic polyamide filaments normally have a high residual shrinkage (approximately 10%) and this property can be used to advantage especially in the preparation of transparent velvet. The residual shrinkage is determined by subjecting a measured sample to an aqueous treatment with or without detergents at a temperature of 95-100 C. for several minutes. This sample which has been subjected to this shrinking treatment in the relaxed condition is then dried in a relaxed condition and its length determined at the same humidity and temperature as the initial measurements. The shrinkage of the yarn after the production of the fabric eliminates the necessity of using a yarn of high twist required when natural silk is used as the ground warp and filling. This shrinkage of the ground fabric results in a pile fabric with a denser and more erect pile. The ground fabric is stronger and permits the use of filaments of finer denier since this shrinkage brings the warp and filling elements even closer together than they can normally be woven. The pile fabrics so produced have a satisfactory hand, are quite compact, and have a very attractive appearance.

By the setting treatment I am able to produce fabrics with many novel effects. In many rugs and carpets it is desirable to have the pile recline uniformly in a certain direction. This is commonly done by mechanical means, such as particular methods of weaving or tying the pile. Some of these methods, as in the production of oriental rugs, are not adaptable to machine operation. Other methods which are adaptable to mechanical operation are still expensive due to the type of construction, etc. These fabrics can be easily and cheaply simulated by arranging the pile in the desired conformation and setting it while held in that position.

Similarly, other novelty effects can be produced by intentional disarrangement of the pile in various ways. This disarrangement may be extended throughout .the fabric, or it may be confined to predetermined areas. The nature of this disarrangement may be uniform, or of various combinations becoming readily apparent. In each case, the desired arrangement may be restrained against further change by setting.

Pile fabrics comprising these synthetic polyamides when out into small segments have high bulking value and are useful as down substitutes in stufilngs for pillows, upholstery and comfortables especially in view of their resistance to attack by mold and insects, low heat conductivity and low moisture absorption. Either straight and/or crimped filaments may be used for this purpose. Cut chenille is particularly advantageous as a down substitute.

The use of synthetic polyamide filaments in pile fabrics has certain important advantages over other filaments, natural or synthetic, both from the standpoint of fabrication and utility of the product. When used as the pile, one of the most important advantages is that the pile has an attractive hand and is inherently and permanently crush resistant. The pile is crush resistant without being stiff; in other words, it is truly resilient. This resiliency is especially valuable in upholstery fabrics since their surface has less frictional resistance than similar fabrics constructcd from other materials. This permits ready movement when seated upon such fabrics which is very important in automotive vehicle upholsteries. This property of true resiliency and the decrease in stiffness is also valuable in that the prickling sensation commonly associated with pile fabrics is not present. Likewise, this resistance to crushing is maintained under conditions of high humidity and temperature. The moisture content of the filaments comprising these fabrics in equilibrium with atmospheres of high humidity is less than that of filaments previously known. Similarly, the fabrics are permanently mothproof and moldproof and do not develop musty DMOI'S in damp weather.

The pile is attractive because of its hand and because of its uniformity of dyeing, absence of greighing oil. and the uniformity of the pile. The pile retains its 'good appearance because of its crush resistance and high abrasion resistance. In fabrics having a cut pile, due to the resiliency of the synthetic polyamide filaments, the pile can be out very uniformly. Costly and damaging brushing, steaming and re-shearing operations are eliminated. The pile has good insulating properties and is not easily damaged.

When the synthetic polyamide filaments are used in the ground fabrics, the pile fabrics produced are strong and elastic, permitting the production of sheer fabrics and fabrics which are creaseproof. When used in combination with synthetic polyamide pile, the crush and crease resistance can be improved by the same hot wet treatment. Since no boil-01f. is required, for ground fabrics comprising these synthetic polyamides, they may be used with other filaments as the pile elements. It is, therefore, possible to use successfully other synthetic filaments such as cellulose derivative or regenerated cellulose rayons. Pile fabrics produced completely from syn thetic filaments of various types of filaments as well as from the same type of filament are, therefore, possible.

Since it is obvious that many changes and modifications can be made in the above-described process without departing from the nature and spirit of the invention, it is to be understood that the invention is not to be limited except as set forth in the appended claims.

Iclaim:

i. As a new article of manufacture an improved dense pile fabric comprising ground warp and weft threads and pile threads, the ground threads of which are composed essentially of synthetic linear polyamide filaments, the ground threads being shrunk, in situ, in the fabric whereby to increase the denseness of the pile.

2. As a new article of manufacture an improved dense pile fabric comprising ground warp and weft threads and pile threads, the ground threads of which are composed essentially of polyhexamethylene adipamide filaments, the ground threads being shrunk, in situ, in the fabric whereby to increase the denseness of the pile.

HAMILTON BRADSHAW.'

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