Method of making burned-out fabric
0 United States Patent 91 in] 3,874, 8 Scholtis et a1. Apr. 1, 1975 METHOD OF MAKING BURNED-OUT 2,901,373 8/1959 Weiss 117/9 FABRIC [75] Inventors: Walter Scholtis, Karl-Marx-Stadt; Primary Examiner-William A. Powell Hans Wallisch, Frankenberg; Attorney, Agent, or Firm-Karl F. Ross; Herbert Wolfgang Stiiber; Sabine Fentiis, Dubno both of Plauen, all of Germany [73] Assignee: VEB Plauener Spritze, Plauen,  
 Germany [57] ABSTRACT [22] Filed: July 1973 A method of making burned-out or etched patterned [21] APPL 331 4 2 fabric, whereby fabrics or filaments of a destructible material forming a fabric with indestructible fibers or filaments. is removed by the patterned application of [52] US. Cl 156/7, 8/114.6, 8/1 15, an etching agent and the subsequent activation thereof 156/85 l56/155&#39; 61/97 by heating. The improvement resides in providing the [51] [131. CI D06q 1/02 removable filaments as mats f unspun filaments [58] Field of Search 156/2, 7 155, 85, 93; corporated into a mesh of the nomemovable 28/76 R; 161/97; 8/1146, 115; 117/11 mems [56] References cued 9 Claims, 11 Drawing Figures UNITED STATES PATENTS 2,317.466 4/1943 Kcrth 8/114.6  
 l um l&#39;n mil PATEiHEUAPR 1125 $874,958  
 SHEET 2 OF 2 NONWOVEN UNSPUN F&#39;ILAMENTS 100!!! STITCHING 0F NONETCHABLE THREAD 33 31 FIG. IO  
 FIG. 6  
 :IlZiZZZIIIII&#39;IIIl WNETCRED FILANENTS 7 700m!&#34; all ill: II. I.  
 FIG. 7  
 STITCHING OF MIN/OVEN MAT 0F EIZ&#39;IMBLE NNIERHABLE TTIREAD UNJPUN FILA HENTT 700MM nus wn YE/KNIT 95 I1 ABRIC FIG. 8  
 METHOD OF MAKING BURNED-OUT FABRIC FIELD OF THE INVENTION The present invention relates to a method of making burned-out fabrics of the type wherein localized destruction of a portion of the fabrics of a fabric web are destroyed and removed to leave a pattern corresponding to that of the localized removal of fabrics. More particularly, the invention relates to an improved method of making etched or burned-out fabric and to a technique for obtaining burned-out fabric at lower cost and with higher quality than has been possible heretofore.  
 BACKGROUND OF THE INVENTION In the production of burned-out fabric or etched fabric, it is known to apply an etchant adapted to dissolve or otherwise remove fabrics or filaments of one chemical composition directly or after thermal activation, to a web containing these etchable or destructible fabrics or filaments incorporated in a fabric of nonetchable or nonremovable fabrics or filaments. When the etching step is completed, the portion of the web to which the chemical etchant was applied contains only the nonetchable fabrics or filaments while those areas to which the etchant was not applied contain both the etchable and nonetchable fabrics and filaments, thereby imparting a texture or pattern to the web. When the etchable fabrics are colored or obscure a color of the base or nonetchable fabrics, the patterning operation may produce color patterns as well as texture patterns and, indeed, both a sculptured effect and a color patterning are customarily obtained.  
  The web is generally a textile fabric which is woven, netted or otherwise produced from continuous filaments or yarn (spun fabric) of the two types or a textile fabric produced from a spun yarn containing both types of fabric.  
  In general, the prior-art technique comprises the formation of a web or textile fabric, with or without individual yarn inlay, consisting of two different yarn types, at least one of which consists of or contains an etchable fabric or filament while the other yarn or filament components is nonetchable. It has been found to be desirable, with the earlier systems mentioned above, to use fine-gauge material, tight weaves or knits, and close spacing of the warp and weft threads of a weave and of wales and courses ofa knit, to maintain a substantially closed surface at locations at which the etchable filaments are removed. Even the etchable filaments, therefore. must be of fine gauge and relatively high cost, in spite of the fact that the etchable filaments are at least in part destroyed or removed. When coarse spun filaments, fabrics or yarn of the etchable material are employcd, difficulties are experienced in holding the fabric web together in the burned-out region because of the precipitation of the spun yarn of etchable material in the fabric construction. It has also been found that such webs create problems with respect to the speed of etching, the controllability of the etching step and/or the degree of etching.  
  In the following description we will use the term burn-out to describe a chemical etching process whereby a pattern can be formed in a web by the localized destruction. solubilization or decomposition of said fibers and filaments, hereinafter referred to as etchable fibers or filaments. The term unspun is used herein to refer to filaments or fibers which are discrete, i.e. non-twisted, and the term spun fibers&#34; or spun filaments&#34; is used to identify normal yarn made up of one or more filaments twisted or spun together.  
  The patterned fabric (with respect to texture, color or both) made by the burning-out process of the present invention, can be employed for any purpose in which conventional etched fabric has been used heretofore, e.g. for drapes, curtains, upholstery, carpets and garments, but finds particular utility as synthetic fur when at least one surface is brushed up or roughened to provide a nap.  
 OBJECT OF THE INVENTION It is the principal object of the present invention to provide an improved method of making an etched-out or burned-out fabric whereby the aforementioned disadvantages are obviated.  
  Another object of the invention is to provide a lowcost method of making high-quality patterned fabrics.  
 SUMMARY OF THE INVENTION These objects and others, according to the present invention, are attained by the formation of a reticule (mesh) of nonetchable fiber and filaments in which is anchored a nonwoven, nonknitted mat of unspun etchable fibers or filaments (fleece) which may be locally removed by chemical techniques as employed in conventional burn-out methods.  
  The invention is based upon our surprising discovery that it is possible to incorporate a nonwoven and nonknitted body (fiber fleece) of unspun filaments of an etchable material having a fiber length greater than mm in a reticulate structure, preferably formed by stitched loops or closely spaced rows of stitching, so that the subsequent etching process (localized) can remove the unspun filaments or fibers or a substantial portion thereof, while leaving a patterned web of high mechanical integrity. One normally would expect, especially where the reticulate structure is formed by closely spaced rows of machine stitches piercing the fiber fleece or mat, the that destruction or chemical solubilization of the fiber fleece would result in deterioration of the mechanical properties of the web since a substantial part of the material which cross-connects the rows of stitching is removed in the etching process. It has been found, however, that burn-out patterning as conventionally employed does not have this effect, presumably because the burn-out process does not remove all of the etchable fibers (which may extend randomly in the fiber fleece or mat and hence include fibers running transverse to the rows of stitching), which remain in the fabric to retain the rows of stitching together.  
  Advantageously, the burn-out process is accompanied by a thermofixing of the nonetchable fibers or filaments (preferably a spun yarn) to further prevent deterioration of the strength characteristics of the fabric in the burn-out region.  
  The resulting patterned fabric may have a sculptured or a textured patterning or a color patterning or both, as noted above.  
  The reticulate or mesh structure in which the fiber fleece is lodged is preferably, as noted, a fabric formed by closely spaced rows of stitches (e.g. chain stitches) with or without crossing filaments or fibers. This fabric, in which sewing-type stitches form the mesh, when provided with a fiber fleece as previously described, will be referred to hereinafter as a fleece/stitched fabric.  
  According to the invention, therefore, the fabric has a destructible component of unspun fibers in the form of a nonwoven fabric strip, sliver or roving, consisting in whole or in part of the destructible yarn. The destructible component may also be provided in the form of unbundled fibers (a random mass which becomes somewhat matted), bundles, tufts and the like.  
  Presumably, fabrics containing fiber fleece have not hitherto been considered useful for making etch-out or burned-out fabrics because it was assumed that the longitudinal stability depended solely upon the characteristics of the sewing filaments while the only transverse stability was solely provided by the mat. When such systems were subject to patterned etching, transverse stability was lost entirely and the fabric had no stability. Surprisingly, when the fibers or filaments of the destructible component have a fiber length in excess of I mm and the transverse spacing of the stitch rows ranges between stitch rows per 25 mm and 30 stitch rows per 25 mm, the deterioration of the fabric upon patterning is avoided entirely. The stitch length may range from 0.4 to 1 mm.  
  According to another feature of the invention, the fleece/stitch fabric is locally printed or padded with a printing paste containing a chemical component adapted to react with the etchable fibers or filaments directly or under the influence of an applied temperature (heating) to effect decomposition of the removable filaments. In general, the localized etchant can consist of etching sulphates, i.e. aluminum sulphate, or strongly oxidized materials such as benzoylperoxide. At the elevated temperatures the aluminum sulphate or benzoylperoxide decompose the etchable fibers which can then be leached from the fabric to leave the nonetchable threads or fibers in the locations at which the fabric had been printed with the etachant.  
  While the invention has been said to be applicable particularly and preferably to fleece/stitched fabrics, other fabric webs in which the nonspun and nontwined etchable fibers are incorporated in a mesh structure, may be used. Such other fabrics may include weft knits and circular knits, in which the unspun etchable fibers are laid in as sliver or bands.  
  The technique of the present invention can produce relatively light nontransparent materials and various patterning effects not hitherto possible. By eliminating the spinning or twisting process for the etchable fibers, the cost of the production is reduced and the different patterns which can be generated are increased. The etchable fibers are preferably composed of viscose rayons or cellulose fibers (hereafter described as viscose fibers), with which a minor proportion (less then 50%) of other fibers such as polyacrylonitrile fibers, which may be etchable in a second step or completely nonetchable, may be combined.  
  The method according to the present invention allows the production of completely novel fabrics. Since the spinning and twisting process is eliminated (for the etchable fibers, as noted above), not only is the finished product cheaper to make, but it can have patterns hitherto unattainable. For instance when viscose fibers are mixed with a small percentage of coarse-titer fibers, such as polyacrylnitrile fibers, the etched out regions of the finished product will be particularly well defined. The use of two different etchable fiber components allows various surface effects, e.g. the simulation of fur, to be achieved with ease.  
  Other effects can be achieved, for example, by combing up the unetched fibers and then etching some of them away. Two different fiber components can be used and one or the other, or both, can be etched away to produce a three-part pattern. A product closely resembling lace can be produced if desired by using shrinkable filaments in the web, and carrying out a shrinkage step for those filaments after etching.  
 DESCRIPTION OF THE DRAWING The above and other objects, features and advantages will now readily become apparent from the following description, reference being made to the accompanying drawing in which:  
  FIG. 1 is a diagrammatic view illustrating the process according to the present invention;  
  FIG. 2 is a plan view of a piece of fabric etched according to the present invention;  
  FIG. 3 is a diagrammatic plan view of a fleece/stitch fabric according to the invention;  
  FIG. 4 is a cross-section through this fabric, drawn to an enlarged scale and taken generally along the line IV-IV of FIG. 3;  
  FIG. 5 is a view of the fabric of FIG. 3 burned-out along a diagrammatic pattern;  
  FIG. 6 is a view similar to FIG. 3, showing another fabric according to the invention;  
  FIG. 7 is a view similar to FIG. 5, showing the burnout fabric of FIG. 6, also with a diagrammatic pattern;  
  FIG. 8 is a section generally similar to FIG. 4 but illustrating another embodiment of the invitation;  
  FIG. 9 is a view similar to FIG. 4 and illustrating still another fabric construction according to the invention;  
  FIG. 10 is a plan view showing the burned-out fabric of FIG. 9 after a first etching stage, and  
  FIG. 11 is an enlarged cross-sectional view showing a brushed-up fabric according to the principles of this invention.  
 SPECIFIC DESCRIPTION As shown in FIG. 1 etchable or destructible fibers from a supply 10, other less or even nonetchable fibers from a supply 9, and an unetchable or relatively indestructible filament from a supply 11 are combined in a knitting, weaving, or meshing machine 12 to produce a continuous striped fabric F. This fabric is then printed with an oxidizing or etching paste at a printing station 13 after which the fabric is passed through a thermaltreatment station 14 where the printing paste applied in station 13 is activated and destroys the filament it is printed on. Thereafter the fabric is washed and rinsed at a washing station 15 and dried and even beaten or brushed up, if necessary, in a drying station 16.  
  The finished product is shown in FIG. 2. This fabric has a continuous surface 17 in which are etched holes 18 where only the web or mesh formed by the filament II is present. Such a fabric is useful for dresses, drapes and similar purposes calling for an interesting pattern.  
  In FIGS. 3 and 4 we show an embodiment of the invention wherein the fleece/stitch fabric 20 comprises a layer 21 which is non-woven and non-netted, i.e. consisting of a mat of pile non-oriented and compressed unspun fabrics having a minimum fabric length of I00 mm and being composed of an etchable material. The mat 21 is stitched through with rows 22 of stitches 23,  
 the spacing D between the rows being of the order of 0.5 to 2 mm so that between l5 and 30 stitch rows are provided for each 25 mm of width of the fabric. The stitches (FIG. 4) having a stitch length L which ranges from 0.4 to I mm may consist of upper threads 24 and lower threads 25 locking the etchable unspun fiber between them. When the fabric is printed with, for example, a diamond pattern of an etchant, the fabric is heated to activate the etchant and thermally fix the stitches 23 at their junctions 26, the subsequent leaching step will remove the unspun fibers in the diamondshaped area 27 which is spanned by closely spaced chains of stitching thread 28 in the form of loops. A tricot stitching pattern may, of course, also be used.  
  In FIGS. 6 and 7, we show a system in which the stitches 33 piercing the mat 31 of unspun filaments are chain stitches while the mat is composed in part of fila ments which are nonetchable (39) and are shown to interconnect the rows 38 of stitches after leaching. FIG. 8 shows that the nonwoven mat 41 of etchable unspun filaments (and a small proportion of unspun nonetchable filaments if the construction of FIG. 7 is to be obtained) is anchored by rows 42 of stitches to a support fabric which may be a fine weave or knit and is represented at 45. In addition, or alternatively, the mat can constitute two or more layers 51a and 51b held in place by superimposed rows of stitching 52a and 52b so that an underlying mat layer 51a is exposed after the overlying layer 51b is removed by etching. This newly exposed layer can be removed in a separate etching operation. FIG. 11 shows that the fibers 60 can be brushed up through the reticulate structure formed by the rows of stitches 62 to impart a fur-like texture to the cloth in those regions in which the nonwoven fabric layers are not removed.  
 EXAMPLE I Fleece/stitched fabric is made of viscose fibers with a staple length of 100 mm and a weight of 420 mtex (3.75 denier), and polyamide silk of a 5 tex mm (Nm 200) weight is used. This fabric has a weight of I00 g/m&#34;, with a gauge of 22F (22 needles/25 mm), or mm 88 wales per decimeter, and a stitch length of 0.63 mm. The fleece is stitched over in a tricot pattern.  
  The fleece knit so made is washed, bleached, and optically brightened. Then it is printed with a paste which is thickened with a galactomannitol and which contains 150 g/kg of aluminum sulfate and is allowed to dry. A local coloring of the polyamide filament can be achieved by the addition of a dispersion dye to the printing paste. Then the fabric is clamped in a tenter frame and heated to [90C for about 30 seconds so that the aluminum sulfate destroys the viscose fibers. Simultaneously, the polyamide filaments are thermally fixed and the dye is irradiated. The destroyed viscose fibers are removed by washing the fabric for 30 minutes in a 50C solution of 2 ml/l sodium hydroxide 38 Be. Then the fabric is rinsed in a solution of l ml/l of 80% acetic acid. then extracted, dried and even beaten, if necessary.  
  The product has closed regions formed by the overstitched viscose fibers and transparent regions which are constituted only by the tulle-like net of the polyamide tricot.  
 EXAMPLE II A fleece fabric formed of 95% viscose fibers, 420  
 mtex (3.75 denier), having a staple length of 100 mm and 5% polyacrylonitrile fibers, I,700 mtex l5 denier) and ofa I00 mm staple length, as well as polyamide silk 5 tex (Nm 200), as stitching filament. The fabric has a weight of 100 g/m with a fineness of 22F and a stitch length of 0.51 mm. The fleece is overstitched in tricot fashion and the fabric is printed with a paste as described in EXAMPLE I, above. The viscose fibers are similarly treated thermally and removed.  
  The end result is that the polyacrylonitrile fibers remain in the regions where the viscose fibers are etched out so as to produce a sharply defined pattern in the laid in coarse-titer polyacrylonitrile fibers.  
 EXAMPLE III Fleece fabric made of a mixture of 50% dull acetate fibers, 340 mtex (3 denier), 100 mm staple length, and 50% shiny viscose fibers, 420 mtex (3.75 denier), 100 mm staple length, stitched in polyamide silk 5 tex (Nm200), with a mesh fineness of 22F. The fabric has a mass of I20 g/m and a stitch length of 0.64 mm, with a tricot knit.  
  This fabric is printed according to the pattern with either or both of the following two pastes, which one or whether both are used being dependent on the pattern effect desired:  
 a. 200 g benzyl peroxide 200 g benzyl acetate 600 g tragacanth thickener b. 150 g aluminum sulfate 150 g water 700 g galactomannitol base thickener The paste a removes the acetate fibers, the paste b the viscose fibers.  
  After printing, the fabric is treated as described in EXAMPLE I and the destroyed fibers are removed in a subsequent beating and washing step.  
  The finished product resembles lace which is overlaid with polyamide silk and has dull acetate fiber regions and shiny viscose-fiber regions.  
 EXAMPLE IV A fleece fabric is made of 30% highly shrinkable polyester fibers 340 mtex (3 denier), of 60 mm staple length and viscose fibers 420 mtex (3.75 denier) held in a mesh of highly shrinkable polyamide filament. This fabric has a weight of g/m The fleece is stitched over with a fineness of 22 F and a stitch length of 0.83 mm.  
  The viscose fibers in the fleece are removed by heat after printing with aluminum sulfate as described above.  
  Subsequently, the so-etched fabric is shrunk by a 30 second contact with a C roller so as to fully shrink the polyamide and polyester which are already somewhat shrunk by the thermal treatment used in printing. This produces a fabric which is more crimped in the regions where the stitches are not full with the fibers, then in the filled regions, so that a relief effect is achieved.  
 EXAMPLE V Fiber bands are produced on a carding machine from a mixture of 50% acrylic fibers and 50% acetate fibers with a mass of 10 g/m These fiber bands are fed to the miniature cards of a fiber-band knitting machine wherein the miniature cards are arranged around the needle cylinder of the machine so as to reduce the bands to fibers and feed these fibers to the needles. The fibers are laid into a base knit formed by the knitting machine from cotton 20 X Ztex (Nm 50/2). The fiber band knit is subsequently printed in a pattern with a paste made of:  
 200 g benzyl peroxide 200 g benzyl acetate, and  
 600 g tragacanth thickener.  
 Then the fabric is dried and treated for 30 seconds in a tenter frame at 190C.  
  The finished product is an imitation fur with a relief surface effect due to the partial etching-away of the acetate fibers. I claim: 1. A method of making a patterned fabric comprising the steps of:  
 combining a body of unspun fibers capable of being dissolved by an etchant with at least one filament not dissolvable by said etchant into a fabric;  
 locally printing said fabric with a paste of said etchant according to a pattern;  
 heating the printed fabric to etch away said fibers in the regions covered by said paste; and  
 shrinking said filament after etching of said fabric.  
  2. The method defined in claim 1, further comprising the step of mixing with the etchant-dissolvable fibers fibers which are not etchant dissolvable.  
  3. The method defined in claim 1 wherein two difierently etchable fibers are used and two different etching pastes are used.  
  4. the method defined in claim 1 wherein said fibers are viscose fibers.  
  5. The method defined in claim 4 wherein said etching paste is an aluminum sulfate compound.  
  6. A method of making a patterned fabric comprising the steps of:  
 combining a body of unspun fibers capable of being dissolved by an etchant with at least one filament not dissolvable by said etchant into a fabric;  
 locally printing said fabric with a paste of said etchant according to a pattern; and heating the printed fabric to etch away said fibers in the regions covered by said paste, said body of unspun fibers being stitched through with rows of stitching and the rows of stitching being provided in 15 to 30 stitch rows per 25 mm of transverse width, the stitch length of the stitches of each row being 0.5 to l mm and said unspun fibers having a length of at least mm.  
  7. The method defined in claim 6 wherein said filament is composed of a thermally fixable synthetic resin and said paste is thermally activatable said fabric being heated to a temperature sufficient to activate said paste and thermally fix said filament.  
 8. The method defined in claim 7 wherein said body of unspun fibers is provided in least two superimposed layers.  
  9. The method defined in claim 7 wherein said body of unspun fibers contains a minor proportion of fibers unaffected by said etchant.