US 3369957 A
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Description (OCR text may contain errors)
Feb. 20, 1968 R. F. CAROSELLI E AL 3,359,957 METHOD FOR RENDERING FABRICS RESISTANT TO WRINKLING AND WEAVE SLIPPAGE AND ARTICLE PRODUCED THEREBY Filed April 10, 1964 2 Sheets-Sheet 1 WW n W E 55 N v50 P W 4 T 60 L 7 E 4 5 u M RWY B Feb. 20, 1968 CAROSELU ET AL 3,369,957
METHOD FOR RENDERING FABRICS RESISTANT TO WRINKLING AND WEAVE SLIPPAGE AND ARTICLE PRODUCED THEREBY Filed April 10, 1964 2 Sheets-Sheet 2 Fig 5 646 Wm M INVENTORS PEMUS E c/woazLL/ & JAMES J. DILLON United States Patent Ofiice Patented Feb. 20, 1968 METHOD FOR RENDERENG FABRHCS RESISTANT TO WRINKLING AND WEAVE SLHPPAGE AND ARTICLE PRODUCED THEREBY Remus F. Caroselli, Cumberland, and James J. Dillon, Providence, R.I., assignors to Owens-Corning Fiberglas Corporation, a corporation of Delaware Filed Apr. 10, 1964, Ser. No. 358,804 17 Claims. (Cl. 161-93) ABSTRACT OF THE DISCLGSURE A glass fiber fabric resistant to weave slippage and wrinkling is produced by heating the fabric to remove its size composition and to obtain a weave set, applying to the fabric surface a continuous protective coating, and curing the coating. A binder is controllably applied to the fabric in such a manner that a substantial number of crossover points formed by warp and fill yarns are bonded without clogging the foramina of the fabric.
The present invention relates to fibrous glass fabrics and to methods for their preparation, and particularly concerns a method for imp-roving the properties of iibrous glass fabrics in which the yarn crossover points of the fabric are bonded.
In the preparation of fibrous glass fabrics, the basic glass filaments are formed from molten glass by means of flowing the glass through minute orifices in a high temperature bushing, grouping a plurality of the fibers into a strand, and simultaneously attenuating the fibers by winding them into a bobbin or package form at speeds as high as 15,000 feet per minute. However, since the glass fibers are mutually abrasive a coating composition termed a forming size is applied to the surfaces of the fibers during their formation, and before the mutual contact of the fibers can yield abrasive conditions and the attrition of the strand. In addition to protecting the fibers from abrasion, this forming size must render the strands suitable for weaving. Specifically, the coating must possess tension properties which will permit the strand to pass through the guide eyes and contact points of the weaving operation and those operations which are preliminary thereto, e.g. twisting, quilling, beaming, etc.
T provide the specified qualities of protection against abrasion, and tensions suitable for weaving, a forming size comprising the dried residue of an aqueous dispersion of starch and/or gelatin has conventionally proved satisfactory. In addition to the starch or gelatin film former, an oleaginous substance such as a vegetable oil of a similarly lubricious compound is usually employed in the forming size in order to further enhance the abra sion resistance and tension characteristics of the strands. Other ingredients such as emulsifiers, surfactants, waterrepelliants, etc., may also be employed in the forming size.
While the foregoing forming size is necessary to carry the glass fibers through the formation and grouping of the fibers, pro-weaving processing, and the weaving phase, it becomes not only non-functional, but even deleterious once the weaving phase is complete. Specifically,'the starch and/0r gelatin film ages and degrades rapidly and is hygroscopic. In addition, it masks the glass surface, to dull the appearance of the fabric and reduce its translucency. Still further, its impermanent nature renders this film unsuitable for the permanent coloration or dyeing of the fabrics. I
As a consequence, the forming size coating is remove-d from the surfaces of the fibers once they are woven into a fabric. Such removal is readily accomplished by means of heat cleaning at temperatures above the decomposition or volatilization point of the ingredients of the forming size, although it may also be achieved by washing, solvent treatment or enzymic action. However, heatcleaning is normally employed since, for other reasons to be discussed, the glass fibers are conventionally subjected to a weave setting operation at temperatures which are adequate to dispel the forming size coating.
Weave-setting is utilized in order to preserve or enhance the retention of the woven form of the fabric and is accomplished by exposing the fabric to temperatures in excess of the softening point of the glass composition which makes up the individual filaments. Upon cooling, the yarns permanently assume the crimped or distorted shape which is the result of their Woven condition. In the absence of such weave setting the stiffness and resiliency of the yarns causes excessive unraveling of the fabric. In addition, weave setting reduces weave slippage within the final fabric, to some degree.
Once the forming size is removed and the fabric has been weave-set, a finishing treatment is conventionally applied. This finish coating is necessitated by the fact that once the forming size is removed the harmful potential of mutual abrasion again comes into play. Since such abrasion may only be avoided so long as the finish remains intact, the film-forming materials are normally selected on the basis of durability. For this reason, synthetic resins such as acrylic resins, polyurethanes, butadiene-acrylonitrile copolymers, and the like, are usually preferred as the film-forming medium of the finish or finish coating. When fabrics devoid of color are desired, transparent resins or those having an index of refraction closely matched to that of the glass fibers are preferred. However, colored fabrics may dictate the utilization of a resin film which is primarily characterized by its susceptibility to dyes or pigments.
Furthermore, since glass fibers are hydrophilic and moisture may intrude to the interface of the glass fiber surface and the finish, to yield harmful results, it is conventional to add a water-repellant to the finish composition. Such hydrophobic compounds are normally Werner chromium complexes such as stearato chromic chloride or methacrylato chromic chloride, but organosilicon compounds such as vinyl trichloro silane, methacryloxy propyl trimethoxy silane, vinyl tris beta (methoxy ethoxy) silane, gamma amino propyl triethoxy silane, and the like, may also be employed.
In addition to the durability which is imparted to the fabric by the finish, the tactile properties, feel or hand of the fabric may also be improved. Specifically, a glass fabric normally exhibits a cold or hard feel such as that of synthetic fabrics, which causes a negative consumer reaction. However, resinous coatings, while hard and cold, exhibit more warmth than glass and this tactile improvement may be further enhanced by rendering the surface of the finish discontinuous, e.g. through the addition of particulate material such as colloidal silica.
It should be noted that the finish coating is normally applied by means of a padder roll which insures the complete penetration of the fabric by the finishing composition. The finished fabric conventionally comprises between .5 to 1% by weight of the finishing composition, in the case of glass fabrics. The quantity of the finishing composition is maintained at a low level because of the fact that larger quantities render the fibrous glass fabrics stiff, heavy, harsh, lacking in drape, and prone to crocking and crazing.
The detailed, foregoing description has been provided in order to clearly establish the environment of the present invention. To this end, the basic, intermediate and final processing of glass fabrics, as well as some of the properties, virtues and impediments of the basic, intermediate and final products, have been presented.
However, the properties of the conventional final product, or fibrous glass fabric, have not been fully detailed. Specifically, the foregoing processes yield a fabric comprised of fibrous glass warp and fill elements and possessed of certain physical and aesthetic attributes. In the first instance, glass fabrics are possessed of much higher strengths than other natural or synthetic fabrics, so long as the previously described effects of mutual abrasion are avoided by the prescribed means, i.e. through the use of a protective coating. In addition, the visual aesthetics of glass fabrics are outstanding. Still further, the dirt and stain resistance of these fabrics is superior in that glass does not absorb nor retain soil and the ability of glass fabrics to be cleaned and to remain clean is only limited by the dirt resistance of the coating composition which is employed in finishing the fabric. Specifically, if a resinous finish which does not retain soil and which is capable of being laundered and/or dry cleaned is utilized, the fabrics will fully reflect these properties and abilities.
As previously mentioned, the tactile aesthetics of glass fabrics leave something to be desired, but when properly finished they are at least equivalent to synthetic resin fabrics such as those formed from polyamide and polyester fibers.
However, despite these qualities, glass fabrics have been limited to static or non dynamic applications such as decorative or fenestration fabrics, e.g. drapery and curtains. This limitation is primarily the result of the weave slippage which is experienced in dynamic utilizations of glass fabrics. Such slippage is realized both upon the hard contact of objects with the fabric to closely compact a portion of the yarns while leaving open spaces in adjacent portions of the fabric, and as a result of stresses placed upon seams and hems. In the latter instances, the thread used to sew such scams or hems physically displaces the yarns of the fabric to leave large, unsightly apertures surrounding the threads. Still further, even the application of longitudinal tension to the fabric will disrupt the fabric and leave contrasting areas of compacted yarns and open or separated yarn. It must be noted that such weave slippage is experienced despite the previously described weave setting in which the yarns are heat softened and permanently crimped in their woven relationship.
It has been possible to overcome weave slippage by means of increasing the quantity of the coating material which is applied to the fabric as a finish. In this technique, the fibrous glass fabric is essentially embedded in a synthetic resin matrix and the properties of the resultant composite are the combined properties of the glass fibers and the coating material. However, as previously noted, the harmful side effects of this expedient far outweigh the benefits of the elimination of weave slippage. In the rst instance, increasing the quantity of the finish coating renders the fabric stiff, unmanageable and unsatisfactory for any application in which drape is desired. Secondly, glass fabrics are inherently plagued by a density or weight problem which is merely magnified by increasing the quantity of finish applied. Furthermore, the hand or tactile qualities are impaired by the stiffness of heavily coated fabrics. In addition, the ability of fibrous glass fabrics to yield a complete recovery from wrinkling is greatly impaired. Specifically, glass fibers possess a 100% elastic recovery which is not shared by the ingredients of the finish coating. Consequently, when heavily finished glass fabrics are wrinkled, the finish coating phase assumes a permanent or semi-permanent wrinkled condition which could not occur in the case of an uncoated glass fabric. Still further, a crocking and crazing problem is experienced when large quantities of the finish are employed. In the former phenomenon the finish coating and its pigmenting materials are transferred to objects which rubbingly engage the fabric, while crazing comprises hair line cracks in the finish coating which lend a white or hazy cast to the fabric appearance. In addition, the breathability or porosity of the fabrics is eliminated by heavy finishes, and renders them unsuitable for such applications a wearing apparel.
In essence, conventionally finished glass fabrics are suitable for static applications but unsatisfactory for dynamic utilizations as the result of weave slippage. Furthermore, while both of these defects may be remedied by means of increasing the quantity of the coating material applied in finishing the fabric, eg from 0.5% by Weight to 4% or more by weight, other intolerable problems are created by this expedient. Of these problems impaired wrinkle recovery and excessive stiffness are paramount. For example, increasing the quantity of finish upon the same fibrous glass fabric from 0.5% to 4% by weight of the total weight of finished fabric greatly reduces weave slippage. However, the fabric finished with 4% by weight is so stiff as to be harsh and board-like, wrinkles readily and does not recover from such wrinkling with any degree of rapidity.
As a consequence of these deleterious characteristics, and the inability of conventional finishing techniques to overcome such characteristics, without creating other severe problems, fibrous glass fabrics are essentially restricted to static or non-dynamic applications such as use in drapery or curtain materials.
It is an object of the present invention to provide methods for rendering fibrous glass fabrics suitable for dynamic applications by diminishing weave slippage without impairing or diluting the desirable properties of such fabrics.
Another object is the provision of fibrous glass fabrics which are devoid of weave slippage but still possessed of their intrinsic desirable properties.
The manner of achieving the foregoing objects, as Well as additional objects and advantages, will be made clear by the following detailed description which is intended to be read with reference to the accompanying drawings, wherein:
FIGURES la, lb and 1c are fragmentary sectional views through the crossover of a warp and fill yarn treated in accordance with the invention,
FIGURE 2 is a perspective view in cross section of a plurality of the warp and fill yarns of a fabric treated in accordance with the invention;
FIGURE 2a is a fragmentary plan view of the fabric shown in cross section in FIGURE 2;
FIGURE 3 is a perspective view in cross section of a plurality of the warp and fill yarns of a fabric treated in accordance with the invention;
FIGURE 4 is a diagrammatic side elevational view of apparatus suitable for carrying out the invention;
FIGURE 5 is a diagrammatic side elevational view of apparatus suitable for carrying out a modified method of practicing the invention;
FIGURE 6 is 'a transverse sectional view taken along plane 6-6 of FIGURE 4 and showing a modified method of practicing the invention.
Essentially, the foregoing objects are achieved by means of adhering all or a portion of the yarn crossover points upon one side of the fabric through the medium of a substantially rigid or partially elongatable bonding material. For the purposes of the present invention a yarn cross over is defined as the intersection of a Warp and fill yarn of a fabric, and a yarn crossover point is the area of surface contact between a warp and fill yarn which exists at a y'arn crossover. When an extensible fabric is not particularly desired a non-elongatable bonding material may be employed and a reduced but perceptible elongation is still experienced due to the ability of the inter adhered yarns to pivot about their mutual or shared point of attachment. However, the utilization of an elongatable bonding material such as an elastomer, permits the stretching or elongation of the entire fabric. In the latter case, the yarns of the fabric may actually undergo a shifting such as that which would be experienced in weave slippage, but will subsequently return to the original weave pattern as a result of the elastic properties of the bonding material.
The basic functioning of the inventive bonding technique and theresultant bonded relationship of the yarns of a fabric treated in accordance with the invention is illustrated in FIGURES 1a, 1b, and 10, which are fragmentary sectional views through the crossover of a warp yarn 11 and a fill yarn 12 in the plane of the warp direction, in which the yarns have been adhered at the crossover point 13 by means of a bonding material 14 utilized in accordance with the invention.
As shown in FIGURE 1a, the bonding material 14 retains the warp yarn 1-1 and the fill yarn 12 in the conventional relationship of the weave pattern under conditions of normal stress.
FIGURE 1b depicts a situation in which a displacing force is applied to either the warp yarn 11 or the fill yarn 12 and a substantially nonelastic material is utilized as the bonding material 14. In such case, the fill yarn 12 is displaced from its normal position as shown by the broken line 15 and pivots about its point of attachment to the warp yarn 11. Naturally, the distance through which the fill yarn 12 may be shifted is limited in this case by the radius formed by the crossover point 13 and that point upon the circumference of the fill yarn 12 which is furthest from the crossover point 13. In essence, the fill yarn 12 merely pivots about its point of attachment to the warp yarn 11, although some slight natural elongation of the bonding material 14 may increase the potential distance of shifting or displacement.
The use of an elastomeric or relatively elastic composition as the bonding material 14 is illustrated by FIG- URE 1c. It may be noticed that the fill yarn 12 is appreciably displaced from its original position as shown by the dotted line 15, as a result of the elongation of the bonding material 14. Upon removal of the force applied, the fillyarn 12 will return to its original position 15, provided that the breaking point of the bonding material 14 is not exceeded.
Obviously, the illustrations of FIGURES 1a, 1b and 1c are fanciful or idealistic to a degree in that it is not practical to deposit a precise amount of the bonding material between the points of contact of each warp and fill yarn. However, these figures are employed to illustrate the ideal form of the practice of the invention and the intra-fabric functions which are achieved through a practical application of the invention.
In order more fully to comprehend the actual practice of the invention and the physical characteristics of fabrics prepared in accordance therewith, a weave structure embodying plural fill and warp yarns, such as is shown by FIGURE 2, must be considered. FIGURE 2 is a perspective view in cross section of a leno weave comprising two adjacent warp yarns 21 and 22, and three adjacent fill yarns 23, 24 and 25 in which the lower surface of the warp yarns 21 and 22 is adhered to the upper surface of the fill yarns 23, 24 and 25 by means of a bonding material 14. It should be noted that the crossover points 26 between the lower surfaces of the fill yarns and the upper surfaces of the warp yarns are not bonded and consequently permit relatively free movement of both the warp and fill yarns in these areas.
For a better understanding of the bonding pattern and physical properties of the inventive fabrics, FIGURE 2a which comprises a fragmentary plan view of the fabric shown in cross section in FIGURE 2, has been provided. It should be noted, as shown by FIGURE 211, that of the six crossover points present, only three of these crossover points, 27, 28 and 29, are interb'onded. Accordingly, only one half of the crossover points are interbonded, since bonding is confined to one side of the fabric.
Again it must be stated that even FIGURES 2 and 2a are fanciful to the extent that it is impractical to deposit 6 a precise amount of bonding material between each available point of contact between the warp and fill yarns on one side of the fabric.
It should also be noted that the weave depicted by FIGURES 2 and 2a, i.e. a leno weave, is characterized by a structure in which the yarn crossover points are equally divided among two different planes which lie adjacent and parallel to a medial plane which is parallel to the two major surfaces of the fabric. Consequently, if the bonding of only one half of the crossover points is desired, the depth of penetration of the bonding material may be limited to encompass only those crossover points which are closest to the fabric surface to which the bonding material is applied. Conversely, if the bonding of all crossover points is sought, penetration must extend beyond the medial plane of the fabric to the crossover points which lie adjacent to the fabric surface opposite to that surface to which the bonding material is applied.
Alternatively, in some weaves, e.g. plain weaves, all of the crossover points lie within a medial plane parallel to the two major surfaces as the result of the fact that both the warp and the fill yarns assume a sinusoidal configuration as opposed to the sinusoidal Warp and relatively straight fill of a leno weave. In such cases it is difficult to selectively bond only a portion of the crossover points in the absence of certain tensioning techniques which will subsequently be described in greater detail.
In order to achieve the bonding of the upper surface of the warp yarns and the lower surface of the fill yarns in a practical manner, one need only deposit a thin bonding film in a limited zone as shown in FIGURE 3. As may be observed, the thickness of the bonding film need only be adequate to span the region 31 defined by the upper surface of the fill yarns 32 and the lower surface of the Warp yarns 33 at the point of contact of the fill and warp yarns. The region 31 defined by the broken lines 31a is merely employed to illustrate the desirable zone of deposition of the bonding material and the latter may, but need not, extend beyond this zone. In fact, it is desirable that the area of bonding does not extend below the general region 31 depicted in FIGURE 3 in order to prevent the bonding of the lower crossover points. It should be noted that the bonding material occupying the region 31 of FIGURE 3 may be deposited as a liquid coating restricted in respect to the depth of its penetration of the fabric, or alternatively as a solid thermoplastic film. In the latter practice the film is deposited ad jacent to the upper surface of the fill yarns and the lower surface of the Warp yarns at their crossover points on one surface of the fabric and then heated to cause the thermoplastic material to flow between the upper surface of the fill yarns and the lower surface of the warp yarns. When a thermoplastic film is employed the thickness of the film is calculated to yield the desired amount of bonding material and the proper positioning of the film may be achieved by means of suction applied to the side of the fabric opposite to that to which the film is applied.
In regard to the deposition of the bonding material, it should be noted that proper positioning is essential. This may be demonstrated for example by treating a fibrous glass fabric which was previously heat cleaned and finished in the manner disclosed by U.S. 3,065,103 with approximately 075% by weight of a finishing composition, with an additional 4% by weight of a finish applied by means of the padder shown by FIGURE 1 of the previously mentioned patent. In contrast, an identical finished fabric was treated with an additional 4% by weight of the same coating material, applied in accordance with the invention. Despite the fact that the two fabric samples contained the same quantity of coating material the dis,- tinction between the two is extensive and impressive. While both are substantially free from weave slippage and mutual abrasion, the fabric which is finished in the conventional manner is extremely stiff, possessed of undesirable tactile properties and characterized by poor wrinkle recovery. In fact, the fabric readily assumes a crumpled form with no tendency to resume its original condition. Upon flattening the crumpled fabric permanent wrinkles may be observed and a crazing or crocking of the finish coating is immediately perceptible. When a pigmented finish is employed under these circumstances, a crocking debility is also experienced.
In contrast, the fabric treated in accordance with the invention exhibits a remarkable wrinkle recovery despite the fact that it is identical with the conventional fabric except in respect to the positioning of an identical quantity of the same coating material, in relation to the fabric structure. Upon crumpling, the fabric immediately reverts to its original condition without perceptible wrinkles. In addition, the inventive fabric possesses a supple and/ or feel in contrast to the stiff or board-like condition of the conventional fabric. Still further, the fabric is free from a tendency to crock or craze. These improvements are combined with a highly satisfactory resistance to weave slippage.
It must also be realized that in practice the application of the inventive bonding materials is not restricted to the crossover points. Specifically, a portion of the coating may adhere to other portions of the single fabric surface to which it is applied. However, it does not normally comprise a continuous coating upon the surface of the yarns and few if any of the crossover points upon the opposite side-of the fabric are adhered. For example, excess portions of the bonding material may adhere to that surface of the yarns to which the coating is applied as shown at in FIGURE 2.
It is also of interest that any bonding of the crossover points which may result from the base finishing coating applied prior to the inventive treatment, is negligible. Specifically, a swatch of a finished fabric was subjected to the action of a textile swing frame designed to break 1 or disrupt any adhesion of the warp and fill yarns at the crossover points. The fabric treated on the swing frame and an identical fabric devoid of such treatment, were then treated in accordance with the invention. There was no perceptible difference between the two fabrics and it is consequently apparent that any adhesion derived from the base finish does not contribute to the present invention.
In this regard, it should be noted that the finish may be applied either before or after the inventive treatments. However, for aesthetic and processing considerations it is preferred to conventionally pad the fabric with approximately .75 by weight of a conventional finishing composition before practicing the present invention. Such a finishing composition normally comprises an aqueous dispersion of a resinous film former such as an acrylic resin, 21 water repellant such as a Werner chromium complex, and may contain pigments, dyes, emulsifiers, inert colloidal particles, plasticizers, diluents, solvents, lubricants, etc. The prior application of the finish is preferred in that a continuous protective film is desired. If the bonding material of the present invention is applied first it may disrupt the fihn provided by the finish composition and may even deter the adhesion of the latter to the glass surface. However if desired, the fabric may be first treated in accordance with the invention and subsequently finished by conventional means.
Further in regard to yarn adhesion at crossover points, i.e. finish compositions versus the inventive treatments, some indication of the basis for the distinction may be derived from a consideration of the adhesive film. For example, a fibrous glass yarn having a diameter of one millimeter and provided with a conventional finish coating of 0.75% by weight would possess a coating film having a thickness of less than two hundred thousandths of an inch if the yarn was incapable of adsorbing any of the coating material. Since such adsorption does occur it is apparent that the actual thickness of the film is less than 0.00002 inch. The lack of appreciable crossover adhesion may be inferred from the fact that a minimum adhesive film thickness of .004 inch is prescribed for industrial and household adhesives. It must be realized that for purposes other than resistance to weave slippage the'extremely thin films of conventional finishes is adequate, and in many instances preferred. For example, a thin coating film protects against abrasion and provides a pigmentable medium while not appreciably detracting from the resiliency, wrinkle recovery, porosity and crocking and craze resistance which are inherent in an untreated fibrous glass fabric. However, such films yield an inter yarn adhesion which is inadequate to resist weave slippage. To that end, the present invention preserves the many desirable features of a conventional thin film finish, while overcoming weave slippage. Essentially, this is achieved by positioning increased quantities of a bonding material to confined areas of the surface of the yarns which make up the fabric and at points where adhesion is desired.
It should be noted that in the principal aspect of the invention, i.e. the bonding of all or a portion of the crossover points of the fabric without depositing bonding material upon the remainder of the fabric, the bonding material is generally introduced to the surface of the fabric, and ultimately to the yarn crossover points. Such an effect may be achieved by a variety of methods. While transfer rolls provided with surface projections which physically transfer the bonding material to the area of the crossover points are preferred, smooth surfaced transfer rolls are suitable under certain circumstances. Specifically, smooth rolls are operable when adequate pressure is employed in that the roll surface contacts the fabric surface and expels the bonding material from that point of contact to leave the fabric surface devoid of the bonding material and the bonding material is then transferred to the area of the crossover points. Naturally if excessive amounts of bonding material are utilized it will be transferred through the thickness of the fabric to provide an undesirable coating upon the surface of the fabric which is furthest from the point of application of the bonding material. Conversely, if the pressure of the applicator and the quantity of bonding material are properly controlled, the bonding material will be deposited at all or a portion of the crossover points as desired, and regardless of whether the crossover points are located in the same or different planes in relation to the fabric surface, while both of the major surfaces of the fabric will be maintained substantially free from the bonding material. In this regard it is preferable that the transfer applicators utilized in the practice of the invention comprise a relatively hard material such as steel, and that the application of the bonding material and the pressurized contact between fabric and transfer roll be achieved substantially simultaneously. In the event that the bonding material is applied appreciably in advance of the pressurized contact, the pressure will merely serve to compact the bonding material upon the surface of the fabric rather than displacing it to the area of the crossover points.
While the foregoing description has dealt principally with a deposition of bonding material which is controlled or selective in respect to achieving bonding at the crossover points with attendant property improvements, a further refinement of the invention is productive of an even more extensive improvement in respect to wrinkle recovery. The latter refinement involves binder deposition which is further selective in respect to which of the crossover points are bonded, and is subsequently discussed in greater detail.
In regard to wrinkle recovery, it appears that this property may be improved by the springiness or resiliency which is extant in a structure which has a single surface coating of a material having properties differing from those which make up the structure, e.g. elastic recovery, stiffness, elongation and modulus of elasticity. A fabric treated in accordance with the present invention may be compared to a prestressed structure in which the resultant structural properties are the cumulative or composite effect of the diverse properties of two distinct materials. This effect, and the consequent wrinkle recovery of the prestressed fabric, is not diminished by the presence of a continuous film of the bonding material upon one surface of the fabric. However, the prestressed effect is neither dependent upon, nor the direct result of such a continuous film and the film when present, merely serves to complement the inventive effect. Instead, the adhesion of yarn crossover points upon one side of the fabric yields a network for the transfer of stresses which provides the desired prestressed condition without impairing the properties of the fabric.
One may more readily derive an appreciation of this achievement through an examination of the fabric depicted in FIGURES 2a and 3. In the first instance, stresses are transferred throughout the extent of the fabric and through the bonded crossovers, despite the fact that not every crossover is bonded. For example, in the weave depicted in FIGURE 2a each yarn is bonded at every other crossover, i.e. 27, 28 and 29. Consequently, there is no disruption of stress transfer within the fabric. However, the inventive method shifts the mean plane of stress transfer to the extent that it does not coincide with the transverse medial plane of the fabric. This results from the fact that all of the bonded points of attachment are located at points adjacent to one side of the transverse medial plane. As a consequence, the mean plane of stress transfer is shifted to yield a prestressed condition and attendant wrinkle recovery.
To illustrate further this condition, one may refer to FIGURE 3. If the fabric depicted in FIGURE 3 was bonded .at all of the crossover points, or entirely free from bonding, the mean plane of stress transfer would intersect the axes of fill yarns 32. However, when bonding is achieved only within the region 31, the mean plane of stress transfer is shifted to a point between the upper limit of the region 31 and the axis of the fill yarns.
It must be realized that such a condition is not precluded by the bonding of some of the crossover points on the opposite side of the fabric. For example, bonding all of the crossover points upon one side of the fabric and a portion of the crossover points on the opposite side of the fabric will tend to shift the mean plane of stress transfer closer to the transverse axial plane of the fabric but the two will not coincide unless there is an equal and balanced bonding of the crossover points on both sides of the fabric. In turn, the bonding of a portion of the crossover points on the opposed side of the fabric will not diminish the tactile properties of the fabric or the crock and craze resistance since these properties are not dependent upon the degree or extent of the bonding of crossover points. Instead, they are dependent upon the quantity of coating materials which is applied to the fabric as a continuous film.
It should also be noted that the utilization of the terminology one side of the fabric" in respect to the positioning of the crossover points is somewhat imprecise in reference to certain types of weaves. For example, a leno weave possesses relatively straight fill yarns and sinusoidal warp yarns. As a consequence, the fill yarns are in the transverse medial plane of the fabric structure and the crossover points are at opposed positions and adjacent to, but not within, the transverse medial plane of the fabric. In such weaves the situation and bonding region depicted by FIGURE 3 are entirely correct. Essentially, the crossover points of either side of the fabric are close to the point of application of the bonding material and readily accessible thereto. In addition, the fact that the crossover points ofboth sides of the fabric are in different planes facilitates the application of bonding material to only those crossover points which occur upon one side of the fabric to the substantial exclusion of the crossover points upon the opposite side of the fabric. However, other weaves present different physical relationships which can entail resort to modified application techniques. For example, in the case of a plain weave all of the crossover points may fall substantially within the same plane, i.e. the transverse medial axis or the medial plane parallel to the major surfaces of the fabric. Consequently, in the treatment of fabrics such as a plain weave in which all of the crossover points fall generally within the transverse medial plane of the fabric, the practice of the inventive methods of binder application are facilitated by the application of tension in either the warp or fill direction of the fabric. In the continuous processing of the fabric, as shown by FIGURE 4, the method lends itself to the application of tension in the warp direction and tension members, e.g. nip rolls, at the input and withdrawal zones adjacent to the transfer roll serve to increase the warp tension which is inherent in the process. Under such stress the warp yarns tend to align within the transverse medial plane of the fabric and simultaneously tend to alternately displace the crossover points above and below the transverse medial plane. As a consequence, a cross section in the fill direction of a plain weave fabric under tension in the warp direction, would correspond to a cross sectional view of a leno weave in the warp direction, such as is shown by FIGURE 3. In the treatment of a leno weave which is under tension in the warp direction a transfer roll with circumferential grooves as shown in FIGURE 6 is not preferred since the lands of the roller will tend to ride upon the projecting fill yarns and not introduce bonding material to the region of the surface of the warp yarns. Accordingly, a knurled transfer roll or one possessing grooves which are parallel to the longitudinal axis of the roll are preferred since such structures will permit the projecting fill yarns to be encompassed by the grooves or recesses of the roller while prohibiting excessive penetration by virtue of the contact between the lands of the roll and the tensioned warp yarns. It should also be noted that the bonding of the crossover points of a plain weave, while the warp yarns are maintained under longitudinal tension, is conducive to the previously described prestressed condition and attendant resistance to wrinkling.
While a prestressed condition has been discussed at length it must be realized that the present invention is not dependent upon such a condition. In essence, the invention resides in the bonding of the crossover points of a fabric while maintaining the balance of the fabric substantially devoid of the bonding material. In this regard even wrinkle recovery is not dependent upon the described prestressed condition and may be achieved by bonding a majority or all of the crossover points while maintaining the balance of the fabric devoid of bonding material and thereby avoiding the problems of fabric stiffness and crazing and crocking. In the first instance, bonding at crossover points reduces weave slippage. Secondly, the presence of large quantities of coating materials upon portions of the fabric other than the crossover points impairs or dilutes the natural resiliency of the fibrous glass yarns with attendant reductions in wrinkle recovery. In addition, the bonding of crossover points permits the transfer of stresses through a plurality of yarns in the same direction. For example, in an unbonded fabric creased or folded perpendicular to the warp direction, parallel warp yarns act substantially independently in recovering from such creasing. However, when the yarn crossover points are bonded the resiliency or ability to recover from wrinkling of any of the creased warp yarns is imparted to its neighbors through the medium of the fill yarn segments which bridge and attach the warp yarns as a consequence of bonding. Similarly, weave slippage is pronounced at the apex or curvature of a crease or fold in a fabric. While the yarns perpendicular to the direction of the crease retain their original relationship, the yarns which are parallel to the crease will undergo shifting. Specifically, the yarns parallel to the crease and on the compression side of the fold will tend to compact or draw closer to one another while their opposite members on the tension side of the fold will undergo a tendency to separate from one another. Accordingly, the recovery of the creased yarns does not yield the original spacing of the weave due to weave slippage and a wrinkle may result from such shifting and gaps in the weave. Alternatively, if the yarns are bonded at their crossovers, both the warp and fill yarns will coact to resist such, distortion and wrinkling, the recovery from distortion will be facilitated by the transfer of the resilience of the distorted yarns, i.e. those perpendicular to the crease, through the medium of the yarns which interconnect them, and the fabric upon being flattened will retain the original weave spacing without wrinkle prone defects occasioned by an absence of yarns in the area of and parallel to the direction in which the fabric was creased.
In essence it may be stated that one aspect of the invention involves the bonding of yarn crossover points while maintaining the balance of the fabric substantially free from the bonding material, while another aspect concerns the bonding of yarn crossover points upon only one side of the fabric, in any given area, while again maintaining the balance of the fabric substantially free from the bonding material. Both methods yield resistance to weave slippage and impart wrinkle recovery while avoiding stiffness, crocking and crazing. However, the second aspect imparts additional wrinkle resistance as the probable result of a prestressed condition.
In the preferred practice of the invention, as shown by FIGURE 4, the bonding material is applied as a liquid by means of a contact applicator. Specifically, and as shown, a finished glass fabric 41 is withdrawn from a payoff roll 40 and is passed in contact with a roll applicator 42, the surface of which is coated with a bonding material 43 dispensed and applied to the surface of the roll applicator 42 by means of a dispensing receptacle 44.
In order to insure a uniform and proper thickness of the bonding material 43 upon the surface of the roll applicator 42 it is desirable to employ a metering blade 45. The bonding material 43 is then transferred from the roll applicator 42 to the surface of the fabric 41. In this regard it should be noted that the quantity of bonding material 43 which is transferred from the sur face of the roll applicator 42 to the surface of the fabric 41 is calculated to bond the warp and fill yarns of the fabric 41 at their points of contact on the side of the fabric 41 to which the bonding material is applied. The coated fabric 46 is then passed through an oven 47 or similar heating means for the purpose of setting the bonding material 43 and is transferred to a take up roll 48. It should be noted that setting of the bonding material is employed in the presently described practice since dispersions of the bonding material in a solvent, diluent, carrier or plasticizer are preferred. In such practice the heating step is utilized to dispel the solvent, diluent, carrier or plasticizer and thereby set the bonding material. However, in the event that the bonding material is applied as a hot melt of a thermoplastic composition which reverts to a set or hardened condition upon cooling to ambient temperatures, the heating step may be eliminated.
It should also be noted that the fabric 41 subjected to the treatment depicted by FIGURE 4 is a finished fabric. By this it is meant that the fabric 41 has been subjected to a weave setting which serves to set the glass fibers and yarns in the distorted or crimped form of the woven fabric. Subsequent to such weave setting and prior to the treatment shown by FIGURE 4, the fabrics were also finished to the extent that a coating adequate to protect the yarns and, which may have been pigmented, was applied to the yarns. Normally, between O.5-l% by weight of finish coating is employed. In this respect the coating applied during finishing may also have served to impart impermanent bonding at the crossover points of the warp and fill yarns of the fabric. However, any such bonding, even in combination with the weave set condition of the fabric, is inadequate to prevent weave slippage. As previously mentioned, weave slippage could be avoided by applying increased quantities of the coating employed in the finishing treatment but such an expedient also serves to impart highly undesirable properties to the fabric. It should also be noted that the finish is conventionally applied to the entire extent of the fabric by means of a padder.
Alternatively, and as previously referred to, the bonding material may be applied by means of a technique such as that depicted by FIGURE 5. Specifically, a thermoplastic film 53 is dispensed from a pay off roll 52 and is deposited upon a finished fibrous glass fabric 51 withdrawn from a second pay off roll 50 and the film 53 is drawn over a guide roll 54 and into intimate engagernent with the fabric 51 by means of suction Supplied by a suction box 55. While the film 53 is maintained in intimate engagement with the fabric 51 it is heated by means of a radiant heater 56 to convert the thermoplastic material which makes up the film 53 into a flowable condition. By controlling the amount of suction exerted by suction box 55, the film 53 may be positioned so that the thermoplastic material flows between the crossover points of the warp and fill yarns on the upper side of the fabric 51. The bonde dfabric 57 is then withdrawn from the influences of heat and suction and transferred to a take up roll 53 whereupon the bonding material supplied by the film 51 sets to a solid condition upon cooling. It should also be noted that the apparatus and method of FIGURE 5 may be modified by substituting solvent applicating apparatus for the radiant heater 56. In such an approach a solvent for the thermoplastic film 53 is applied, e.g. sprayed upon the film 53, in the zone in which heat is applied in FIGURE 5. As a consequence of dissolution in the solvent, the material which makes up the film 53 is caused to flow between the warp and fill yarns at the crossover points and may subsequently set by means of dispelling the solvent, e.g. by heating.
It must also be realized that the inventive goal may be achieved when only a portion of the warp and fill yarns upon one side of the fabric are bonded. For example, the bonding material may be applied to spaced or discontinuous zones of one surface of the fabric. This maybe readily accomplished by applying spaced, parallel strips of the bonding material to one surface of the fabric. Alternatively, a roll applicator with a surface engraved or embossed in a discontinuous pattern may be employed. The suitability of spaced or discontinuous bonding may be perceived when one considers the mechanics of weave slippage. Specifically, weave slippage comprises the response of the weave pattern to applied forces in which the combined factors of the spacing existing between adjacent, parallel yarns and the compressibility of the yarns, permits them to shift within the weave pattern. During such shifting, a plurality of adjacent, parallel Yarns are compacted and compressed to yield a dense region in the fabric and an adjacent hole or region whch is devoid of yarn due to shifting. If each crossover point upon one side of the fabric is adhered a large resistance to weave slippages is realized. However, when only a fraction of the crossover points are adhered an adequate resistance is achieved. For example, in a fabric woven from yarns one unit in diameter, which are compressible to one half their original diameter, and which are normally spaced from adjacent yarns by one half unit, the harmful effects of weave slippage are extensive in the absence of any bonding of the crossover points, As an instance, the application of a force adequate to shift and compress adjacent yarns would yield a dense or compacted fabric area 50 units in width and an adjacent hole measuring 100 units in width. In contrast, if every fifth yarn in the series of parallel yarns is adequately adhered at a portion or all of its crossover points, any weave slippage is limited to a 13 dense area having a width of 2 units and an adjacent hole having a width of 4 units. In addition, the recovery of the fabric from such minor slippage is facilitated by the fact that the zone of slippage is bordered upon each side by adhered yarns which tend to realign those yarns which have undergone slippage.
When such discontinuous bonding is desired a method for its achievement is shown by FIGURE 6 which depicts the application of a bonding material by means of contacting a leno weave fabric with a roll applicator having a surface provided with spaced embossed segments, in a view taken through plane 66 of FIGURE 4. Specifically, a glass fabric is passed in contact with a roll applicator 61 the surface 62 of which is provided with spaced embossed sections 63. It may be noted that the embossed sections 63 are provided with lands 64 which are spaced to project between adjacent pairs of warp yarns 65 on the surface of the fabric which is contacted with the roll applicator 61, and to contact the upper surface of the fill yarn 66 at a point equidistant between the warp yarns 65. In the use of a roll applicator such as that depicted, a liquid bonding material 67 is applied only to the embossed sections 63 of the roll applicator 61. As a consequence, only those warp yarns 65 which are contacted by the embossed sections 63 are bonded to the fill yarn 66 while the warp yarns 65 which are adjacent to the unembossed surface 62 of the roll applicator 61 are not bonded. To insure proper penetration of the fabric, a back up pressure roll 69 is employed in conjunction with the applicator 61. It may be observed that the bonding material 67 is forced to surround the warp yarns 65 upon the upper surface of the fabric and to flow into the point of contact 68 of the warp yarns 65 with the fill yarn 66. It should be noted that a thorough, metered, bonding of the warp yarns to the fill yarns may be achieved by means of a roll applicator having a completely embossed or knurled surface. Furthermore, the embossed sections 63 need not extend about the entire circumference of the roll applicator 61, but may be discontinuous, e.g in a checkerboard or spaced pattern. In essence, the extent of the bonding imparted to the fabric should be calculated to provide the requisite resistance to weave slippage in view of the adhesive power of the bonding material which is employed, the weave design and the contemplated end use of the fabric, i.e. fabrics intended for use in rigorous environments such as wearing apparel may require that substantially all of the crossover points be bonded.
While the discussion of the inventive methods have been principally restricted to metered contact transfer apparatus or the deposition and subsequent in situ liquifaction of the film, other methods are suitable so long as adequate control directed toward the proper penetration and positioning of the bonding material. For example, other methods of metered contact such as knife coating, screen printing, etc., may be employed, while suitably controlled spraying, fluidized bed techniques, etc., may also be utilized.
In addition, a broad range of bonding materials may be employed. While dispersions of polyurethane resins, polyvinyl alcohol, polyvinyl acetate, acrylic resins such as printing clears formed from acrylic resins and copolymers, butadiene-acrylonitrile copolymers, cellulose acetates, cellulose, polyamides, polyolefins, etc., are generally suitable, a polymethylmethacrylate emulsion is preferred for metered transfer applications such as those shown by FIGURES 4 and 6, while a polyurethane film is preferred in applications such as that shown by FIGURE 5.
As may be perceived, the quantity of the bonding material applied to a fabric is dependent upon the degree of bonding desired or required, the structure of the fabric including yarn diameter, degree of twist, the spacing between adjacent parallel yarns, the fluidity and penetrating power of the bonding material, and the like. Ideally, in the complete bonding of all of the contact crossover points upon one side of a fabric, the quantity of bonding material would be simply that computed as necessary to adhere each contact point as based upon the surface area of the point of contact, the number of points of contact, and the adhesive strength of the bonding material. However, as previously stated, it is extremely difficult to deposit a precise quantity of bonding material at each contact point of the warp and fill yarns. Consequently, the quantity of bonding material must be adjusted for each combination of fabric structure, application method for the bonding material, extent of bonding, tag. all or a portion of the contact points, and the penetration and adhesive power of the bonding material.
Further difficulty in respect to generally prescribing the quantity of bonding material to be employed is occasioned by the fact that the inventive techniques have re- -moved previously existing quantitative barriers. Specifically, quantities normally applied as finishes to conventional weaves were previously restricted to between 0.25 to 4% if the hazards of stiffness, crocking, crazing, etc., were to be avoided. With the present inventive methods, quantities in the range of 48% by Weight (total weight of finishing composition and bonding material) are productive of fabrics possessing highly desirable properties and devoid of the detriments which normally attend the use of such quantities of coating materials. Accordingly, while it is necessary to vary the quantity of bonding material for each weave structure, bonding material, application technique, etc., it may be generally stated that the preferred practice of the invention involves the use of between 0.25-4% by weight of a finish coating applied to the entire surface of the fabric as a continuous film, and between 0.5-7% by weight of a bonding material applied only to the crossover points of the yarns which make up the fabric. The foregoing percentages by weight are based upon the total weight of fabric, finish composition and bonding material. In addition, the quantity of bonding material is subject to a fluctuation in methods in which only a portion of the crossover points are bonded.
In order to provide standards of reference which will permit the practice of the invention, as well as the derivation of obvious modifications, the following examples set forth a variety of fabric structures, bonding materials, quantities of bonding materials, and methods of application of the bonding materials:
EXAMPLE 1 Ethyl acrylate, acrylic acid copolyrner (sp. gr. 1.05,
pH 2.8) Antimony oxide 1.25 Carboxy methyl cellulose 0.75
The foregoing composition was applied as an aqueous emulsion with the antimony oxide added both as a dulling agent and a fire retardant. The entire surface of the transfer roll was engraved (70 lines per inch) in a knurled pattern wherein the engraved lines intersect at a angle and all of the lines form a 45 angle with the longitudinal axis of the roller.
The surface of the fabric which was not contacted by the transfer roll was checked throughout the coating step and did not exhibit the dampness which would occur if the coating material was to penetrate through the thickness of the fabric. In addition, the back up roll which maintained the fabric in contact with the transfer roll was completely devoid of coating material at the end of the operation. Immediately following the coating step the fabric was passed through an oven maintained at 300 F. to dry or set the coating which had been applied.
1 EXAMPLE 2 A crowfoot weave fabric (88 ends of B450l/O x 78 picks of B4501/2) was roller coated with 5.9% by weight (based on solids) of the following ingredients:
Percent by weight Ethyl acrylate, acrylic acid copolymer of Example 1 25 Water, remainder.
The transfer roll possessed a smooth surface and the fabric was heated at 300 F. to setthe coating. Again there was 110 indication that the coating emulsion penetrated the fabric.
EXAMPLE 3 A twill weave fabric (88 ends B-4501/0 X 78 picks B4501/ 2) was knife coated with 4% by weight (based on solids) of the following solution:
Percent Polyurethane 11 Tetrahydrofuran 44.5 Cyclohexanone 44.5
The coated fabric was then heated to a temperature of 475 F.
EXAMPLE 4 Employing apparatus similar to that depicted by FIG- URE 5, a polyethylene film (.5 mil thickness) was superimposed upon a fabric of the construction employed in Example 2 and suction was applied to the opposite side of the fabric. The amount of suction was increased until the warp and fill yarns of the fabric were readily perceptible through the polyethylene film but maintained below that point at which the film was bursted under pressure. Radiant heat adequate to raise the temperature at the fabric surface to approximately 300 F. was applied until the flowing of the film was perceptible. Heat was then removed and the fabric was permitted to cool. The fabric was then subjected to a high pressure air jet for the purpose of removing remnants of the polyethylene film from the foramina of the fabric.
In all of the foregoing examples the fabrics, regardless of construction or weave, had been subjected to a finishing step prior to treatment in accordance with the invention. Specifically, the fabrics were heat cleaned at a temperature adequate to completely remove the starch based Percent by weight Ethyl 'acrylate, acrylic acid copolyrner 9.9 Epoxidized soya oil 9.9 Emulsified (alkyl aryl polyether alcohol) .02
The above finished coating was then cured at a temperature of 250 F.
It should be noted that the attainment of the bonding of the crossover points of only one side of the fabric may be controlled by a number of means, and is necessarily varied for each type of fabric, e.g. depending upon the openness of the weave, weaving tensions, etc. Some of the methods for controlling the proper deposition of the bonding material include the form of engraving or embossing utilized upon the transfer roll, e.g. deeper grooves for increased pick up and transfer, modifaction of the pressure between the transfer roll and the back up roll, and changes in the viscosity of the bonding material by means of the manipulation of the percentage of solids or the addition -of thickening agents, e.g. carboxy methyl cellulose, so-
dium alginates, etc. In addition, the control of the degree or depth of penetration by the bonding material may be achieved by means of the use of a compressible coating upon the back up or back pressure roll. For example,
in the pressurized treatment of a fabric in the nip of a transfer roll and back up roll, the presence of a cornpressible material such as soft rubber upon the circumferential surface of the back up roll will yield a condition in which the compressible material is deformed and projected within the foramina of the fabric. As a consequence, the bonding material entering the opposite end of the foramina is prevented from completely penetrating the fabric and is accordingly confined to the region in which bonding is desired, ie. the crossover points upon the side of the fabric to which the bonding material is applied.
In the use of film coatings, air pressure may be utilized to insure the proper positioning of the bonding material within the fabric when suction is employed. However, bonding materials in the form of films may also be utilized in combination with 'a heated knurled transfer roll. In the latter case, the teeth or projections upon the surface of the transfer roll tend to thrust the film within the fabric foramina where the heat causes them to flow and penetrate the yarn crossover points. In such techniques, the length of the projections is designed to prevent the complete penetration of the fabric and the transfer roll is coated with a material which is not adhesive in relation to the thermoplastic film, ie. the film preferentially adheres to the glass fibers. In addition, the flowing of the film may be achieved by the application of heat or solvent from the side opposite to that contacted by the toothed roller.
Swatches of the fabrics of Examples 1-4 were sewed to swatches of identical fabrics which differed only in respect to the absence of the inventive treatment. In each instance, the application of a tensile stress perpendicular to the seam yielded gapping or weave slippage around the thread utilized to sew the seam, while such an effect was not observed in the case of the fabrics treated in accordance with Examples 1-4.
In addition, the same fabrics employed in the examples were subjected to a finishing operation in which identical quantities of the same bonding materials were applied by conventional means. In each instance, the conventionally treated fabrics Were characterized by a stifiness which would render them unsuitable for the great majority of decorative and utilitarian uses of both a static and a dynamic nature. In addition, these fabrics exhibited poor wrinkle recovery and were plagued by crazing and crocking. In contrast, the fabrics treated in accordance with the invention were superior in all respects despite the fact that identical weaves bearing identical quantities of the same bonding material were involved. It must be realized that the only distinction between the suitable and unsatisfactory fabrics resided in the method of application of the bonding materials, and, more fundamentally, in the final positioning of the bonding materials in relation to the fabric structure.
It should be noted that the methods of the invention are suitable for in-line use with conventional heat cleaning, weave setting and finishing equipment. Specifically, a fibrous glass fabric may be continuously passed through an oven maintained at a temperature adequate to achieve the removal of weaving sizes and the heat setting of the yarns (1200 F.) then passed through a conventional padder such as shown by US. 3,082,734 which completely coats the fabric with approximately 0.75% by weight of a protective material, and reheated to a temperature adequate to set the protective coating (300 F.). Without interruption, the fabric may then be passed into contact with a transfer roll which deposits a bonding material at the crossover points of the warp and fill yarns on one side of the fabric and the bonding material may be set by means of heating. For example, the method of FIGURE 4 can be employed in conjunction with, and subsequent to the heat cleaning and finishing method which is shown by FIGURE 1 of U.S. Patent 3,065,103 and described by the specification of that patent.
It should also be noted that specific weave designs may require some modifications of the methods previously discussed. For example, fabrics provided with a single surface effect may dictate that the inventive treatment be applied only to the back or undercoated surface of the fabric. Similarly, a multiple pick fabric construction could require the bonding of all of the crossover points upon one surface of the fabric, while more conventional weaves may only require widely spaced bonded zones.
It is also significant that while a refinement of the invention has been described as the bonding of the crossover points upon only one side of the fabric, it might be more precisely described as the bonding of the crossover points of one side of the fabric, in any given region of the fabric. Specifically, the inventive effect, with some reduction in wrinkle recovery, may be achieved by bonding crossover points upon both sides of the fabric, so long as the areas of bonding on the opposite sides of the fabric do not coincide. For example, fabrics could be passed through the nip of two opposed transfer rolls having embossed areas or application zones which intermesh rather than contacting. In that instance, the bonding material applied to each side of the fabric would not be permitted to penetrate fully the fabric and bonding would be restricted to the crossover points adjacent to the point of application. Accordingly, the inventive methods are most precisely defined as the bonding of the crossover points of only one side of the fabric in any given area of the fabric. Alternatively, this situation may be negatively expressed as the avoidance of the bonding of opposed crossover points.
It should also be noted that the utilization of the present invention does not preclude resort to subsequent coatings designed for special properties; e.g. fiuorinated olefins or acrylics for water repellancy or stain resistance.
In addition, while the foregoing description has related to fibrous glass fabrics, and although the invention has particular utility in regard to fibrous glass fabrics, it must be realized that the methods of the invention are useful in the treatment of other synthetic fabrics, e.g. polyamide, polyester, etc., as Well as natural fabrics such as cotton, wool, etc.
It is apparent that new and improved methods for the preparation of fibrous glass fabrics, as well as new and improved fibrous glass fabrics have been provided by the present invention.
It is further obvious that various changes, alterations and substitutions may be made in the practice of the invention without departing from the spirit of the invention as defined by the following claims.
1. A fabric resistant to weave slippage, wrinkling and abrasion, comprising woven fibrous glass warp and fill yarns, a continuous protective coating comprising a hydrophobic compound upon the surfaces of said warp and fill yarns, said protective coating comprising between 0.25 to 4% of the total weight of said fabric and said protective coating, and a flexible bonding material from the group consisting of polyurethane, polyvinyl, and acrylic resins and copolymers, located only at a plurality of the crossover points of said warp and fill yarns on one side of the fabric, said bonding material comprising between 0.5 to 7% of the total weight of said fabric, said pro tective coating and said bonding material.
2. A fabric resistant to weave slippage, wrinkling and abrasion, comprising woven fibrous glass warp and fill yarns, a continuous protective coating comprising a hydrophobic compound upon the surfaces of said warp and said fill yarns, said protective coating comprising between 0.25 to 4% of the total weight of said fabric and said protective coating, and a flexible bonding maten'al from the group consisting of polyurethane, polyvinyl, and acrylic resins and copolymers, said bonding material being located only at a plurality of non-opposed crossover points of said warp and said fill yarns on both sides of the fabric and comprising between 0.5 to 7% of the total weight of said fabric, said protective coating and said bonding material.
3. A method for rendering a fabric composed of woven warp .and fill yarns resistant to weave slippage and wrinkling, comprising controllably applying an amount of bonding material to said fabric insufficient to saturate the foramina of the fabric and depositing said bonding material only at the crossover points formed by said warp and said fill yarns on one side of the fabric while maintaining the remainder of said fabric substantially free from said bonding material.
4. In a method for rendering a fabric composed of woven warp and fill yarns resistant to Weave slippage and wrinkling, comprising applying a liquid bonding material to said fabric the improvement comprising depositing said bonding material at only a plurality of crossover points of said warp and said fill yarns on one side of the fabric while maintaining the remainder of said fabric substantially free from said bonding material so that the unbonded warp and fill yarns can controllably displace and return within the fabric.
5. A method for rendering a fabric composed of woven warp and fill yarns resistant to weave slippage and wrinkling, comprising applying a bonding material to a plurality of projections upon the contact surface of a transfer member, contacting a major surface of said fabric with said projections, inserting said projections within the interstices of said fabric and in proximity to the crossover points of said warp and said fill yarns, and depositing said bonding material at said crossover points while maintaining the remainder of said fabric substantially free from said bonding material.
6. A method as claimed in claim 5 in which said transfer member is a cylindrical transfer roll having embossments upon its circumferential surface.
7. A :method as claimed in claim 5 in which said bonding material consists essentially of a synthetic resin selected from the group consisting of polyurethane, polyvinyl and acrylic resins and copolymers.
8. A method for rendering a fabric composed of woven fibrous glass warp and fill yarns resistant to weave slippage, wrinkling and abrasion, comprising coating the surfaces of said fabric with a continuous protective coating, curing said coating, applying a bonding material to an embossed transfer member, contacting the fabric with said transfer member so that the embossments thereon insert to the proximity of the crossover points of said warp and fill yarns, thereby depositing said bonding material at said crossover points while maintaining the remainder of said fabric substantially free from said bonding material. 4
9. A method for rendering a fabric composed of woven fibrous glass warp and fill yarns coated with a size composition, resistant to weave slippage, wrinkling and abrasion, comprising subjecting said fabric to temperatures adequate to remove said size composition, coating the surfaces of said fabric with a continuous protective coating, curing said coating, applying a bonding material to said fabric via a transfer member with projections thereon so that said bonding material is fed to the fabric via the projections, and depositing said bonding material at the crossover points of said warp and said fill yarns by inserting said projections into the fabric while maintaining the remainder of said fabric substantially free from said bonding material.
10. A method as claimed in claim 9 in which said temperatures are also adequate to soften said fibrous glass and weave set said fabric.
11. A method for imparting resistance to weave slippage and wrinkling to a fabric composed of woven warp and fill yarns in which substantially all of the crossover points of the warp and fill yarns lie between the major surfaces of the fabric and a medial plane parallel to the major surfaces of the fabric, comprising applying a bondremainder of said fabric substantially free from said bonding material, and confining said bonding material at any given point upon the fabric to said crossover points which are adjacent to only one side of said medial plane.
12. A method for imparting resistance to weave slippage and wrinkling to a fabric composed of woven warp and fill yarns in which the crossover points of the warp and fill yarns lie substantially within a medial plane parallel to the major surfaces of the fabric, comprising applying longitudinal tension to said warp yarns to displace said crossover points to a point adjacent to said medial plane, applying a controlled amount of bonding material to said fabric via a transfer member having projections thereon and depositing said bonding material via the projections at said crossover points while maintaining the remainder of said fabric substantially free from said bonding material.
13. A method as claimed in claim 12 in which said longitudinal tension is applied to said fill yarns.
14. A method for imparting resistance to weave slip page and wrinkling to a fabric composed of woven warp and fill yarns in which the points of contact between the warp and fill yarns lie between the major surfaces of the fabric and a medial plane parallel to the major surfaces of the fabric, comprising applying a liquid bonding material to radial projections provided upon the circumferential surface of a rotating cylindrical transfer roll, passing one major surface of said fabric into tangential intimate engagement with said circumferential surface with the longitudinal axis of said fabric in a perpendicular relationship to the longitudinal axis of said transfer roll, inserting said radial projections beneath said major surface and in proximity to the crossover points which lie between said medial plane and said :major surface, and depositing said bonding material at said crossover points while maintaining the remainder of said fabric substantially free from said bonding material.
15. A method for rendering a fabric composed of woven fibrous glass Warp and fill yarns resistant to weave slippage, wrinkling and abrasion, comprising applying a continuous protective coating to the surfaces of said warp and said fill yarns, said protective coating comprising between 0.25 to 4% of the total weight of said fabric and said protective coating, controllably applying .a bonding material to a transfer member having a plurality of projections thereon, contacting the fabric with said transfer member, thereby to deposit a bonding material at the crossover points of said warp and said fill yarns while maintaining the remainder of said fabric substantially free from said bonding material, said bonding material comprising between 0.5 to 7% of the total weight of said fabric, said protective coating and said bonding material.
16. A method for rendering a fabric composed of woven warp and fill yarns resistant to weave slippage and wrinkling, comprising controllably applying an amount of bonding material to said fabric insufiicient to saturate the foramina of the fabric and depositing said bonding material only at the crossover points formed by said Warp and said fill yarns on both sides of the fabric in such a manner that opposed crossover points are not bonded, while maintaining the remainder of said fabric substantially free from said bonding material.
17. In a method for rendering a fabric composed of woven warp and fill yarns resistant to weave slippage and wrinkling, comprising applying a liquid bonding material to said fabric, the improvement comprising depositing said bonding material at only a plurality of crossover points of said warp and said fill yarns on both sides of the fabric in such a manner that opposed crossover points are not bonded, while maintaining the remainder of said fabric substantially free from said bonding material so that the unbonded warp and fill yarns can controllably be displaced and return within the fabric.
References Cited UNITED STATES PATENTS 2,050,156 8/1936 Borghetty 161-92 X 2,771,659 11/1956 Ball 16189X 2,879,581 3/1959 Evans et al "161-93 3,065,103 11/1962 Marzocchi 117 54 ROBERT F. BURNETT, Primary Examiner. ALEXANDER WYMAN, Examiner.
R. H. CRISS, Assistant Examiner.