US3012925A

US3012925A - Rayon fabric

Info

Publication number: US3012925A
Application number: US776433A
Authority: US
Inventors: Jr Horace P Fry
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1958-11-26
Filing date: 1958-11-26
Publication date: 1961-12-12
Anticipated expiration: 1978-12-12

Description

vcially a non-woven fabric, and

3,012,925 RAYON FABRIC Horace P. Fry, Jr., West Chester, Pa.,- assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Nov. 26, 1958, Ser. No. 776,433

' 4 Claims. (Cl. 156-181) This invention relates to a method of making a high strength, low-extensibility open-mesh rayon fabric, espemore particularly to a method of making such a fabric from ordinary, unstrained, low-twist viscose rayon yarn.

It is an object of this invention to provide an improved method of making an open-mesh rayon fabric, especially a non-wo en fabric, having a relatively low degree of extensibility.

It is a further object to provide a method of making a non-Woven rayon fabric of low extensibility which permits the use of an aqueous adhesive solution for binding the yarns of the fabric together at their crossing points.

It is still another object of the present invention to provide a method of making a low-extensibility non-Woven rayon fabric from ordinary, unstrained, low-twist viscose rayon yarn.

Another object of the invention is to provide an economical method of making a lo -extensibility open-mesh rayon fabric.

-Other and further objects, features and advantages will become apparent as the description of the invention proceeds.

The usual continuous filament viscose rayon yarn, unless highly twisted, has an extensibility of approximately 18% when dry'and 22% when wet before its full strength is realized andthe yarn breaks. This high extensibility can be considerably reduced, say to about 8% or even less, if during initial manufacture or subsequently the yarn is subjected to a slashing operation wherein the yarn is wetted and then held under tension while drying. However, the reduced extensibility brought about by slashing is destroyed if the yarn is subsequently gotten wet and allowed to dry in a rel-axed or untensioned condition and consequently slashing is ordinarily only employed when the yarn is to be used in a manner wherein it is protected from water, as for example, for tire cord.

Open-mesh fabric known as scrim, which may be either woven or non-woven has a wide variety of uses. Obviously, in the case of non-woven scrim, the yarns making up the fabric must be secured together at their crossing points in order to hold the fabric together and this is customarily accomplished by means of an adhesive. It is also customary to employ an adhesive to secure the yarns together at their crossing points in woven scrim, especially in the case of wide mesh scrim. Because the individual threads or yarns of scrim are not closely packed together as they are in a closely woven fabric, the scrim has an extensibility substantially equal to that of the individual yarns of which it is formed. Thus, scrim formed of ordinary, unslashed, low-twist rayon yarn has an extensibility of approximately 18% when dry and 22% when wet. 'Scrim formed of slashed rayon yarn has a much lower extensibility but the adhesive employed must not contain water or be applied as a water emulsion or suspension unless the individual yarns are maintained under tension until the fabric is completely dry, for otherwise the low-extensibility characteristic of the yarn is destroyed, as mentioned above. While there are certain volatile adhesives which may be used which do not impair the low-extensibility of the yarn, these create undesirable and expensive problems in connection with solvent recovery, ventilation, fire hazard, etc. On the other hand, when an aqueous ad- 3,012,925 Patented Dec. 12 1961 hesive liquid is employed, the mechanisms necessary to maintain the yarn under tension until dry are com: plicated and the fabric forming operation generally has to proceed at a slower rate. While a scrim of low extensibility is ideally suited as a reinforcing lamina for paper or other sheet material, the above-mentioned problems in connection with forming the scrim of a lowextensibility rayon yarn have limited its use for this purpose.

According to the present invention an ordinary, unslashed, low twist, viscose rayon yarn is employed to obtain an'open-rnesh fabric having the low extensibility of a fabric formed of a slashed yarn. Furthermore, the yarn is neither dried nor sized and is therefore considerably less expensive than that heretofore employed in making fabric.

While there are several extensively used processes for making viscose rayon yarn, differing in specific detail and in the order in which some of the steps are performed, in general the essential steps can be said to comprise extruding viscose through a spinneret into an acid bath which coagulates the viscose into a strand, stretching the strand to orient the molecules, washing the strand in a relaxed or untensioned state to remove excess acid, and winding it into a package. The spinneret generally contains a fairly large number of holes or orifrees so that the strand is composed of a multiplicity of filaments and there are usually a number of additional steps'iu the process, known as after treatments, but these need not be enumerated here. There is, however, one other stepusually considered a step in the manufacturing process which requires a energy and which in some processes involves manual manipulation of the yarn. This is the drying of the yarn and when making the fabric in accordance with the present invention this expensive, and in some instances time-consuming, step is eliminated.

In the so-called continuous process, the yarn passes through a number of treating baths or otherwise has applied thereto at different times a number of liquids, after which the yarn passes through a drying chamber or around heated rollers and finally is wound or collected on a bobbin. With the present invention, as noted above, the drying stage is eliminated and the last bath or liquid applying station is used to apply an aqueous adhesive solution to the yarn which is then immediately wound into a package. In order that the collected yarn will have a uniform coating of adhesive, an excess amount may be applied and the excess removed by a wiper before collecting the yarn. While there are a large number of adhesives which may be employed, polyvinyl alcohol, animal glue, oarboxymethyl cellulose and aqueous latex emulsions are suggested as suitable.

In the so-called pot spinning process, the yarn is collected in a rapidly rotating pot or bucket right after the stretch orientation step or after the initial washing, the after treatments being performed while the yarn is in the form of a cake. If the yarn to be used in practicing the present invention is made by this process, the aqueous adhesive liquid, which may be the same as mentioned above, is applied to the yarn in cake form after the usual after treatments. The adhesive may be applied in an excess amount and the excess removed by centrifuging to leave a uniform coating. The yarn may either be left in cake form or wound onto a bobbin but in either event it is not dried.

The yarn prepared by either of the above methods is stored in a highly humid atmosphere to prevent the adhesive from drying. It is then formed into an openmesh fabric either by weaving on a loom or on any of various known scrim making machines wherein the fill strands are laid in spaced parallel arrangement over the considerable amount of spaced: warp strands. Thus the fabric is formed from ordinary stretch oriented but unstrained yarn. The adhesive coating is undried at the time of formation of the fabric and as will be appreciated the adhesive, while still wet, serves as a lubricant and eliminates the necessity for employing the usual sizing material.

As previously noted, the thus formed. fabric. has. an extensibility substantially thev same as that of the; yarn. and, since the yarn has not been slashed or. driedv under. strain, this extensibility is about 22% while the fabri'cis still wet. After passing throughv the loom or scrim making machine, the fabric is led through aitenterv frame and dried'while heldtaut by; the tenter frame to thus-prevent shrinkage and imposed internal strains on the yarn. The drying of course sets the adhesive and the tension imposed by the tenter frame causesthe extensibility ofthe yarnand" the fabric to be reduced from about 22% to about 8%. g If desired, and it frequently will be desired,, the extensibility may be reduced even more by actually stretching the fabric on the tenter frame before drying. it is to be noted that the drying step normally-employed in manufacturing the yarn has actually been eliminated and not merely postponed until after the formation of the fabric because if aqueous adhesive solutions are used in the making of the fabric, the fabric would have to be dried anyway evenif made from initially dry yarn. The

advantages of employing aqueous adhesive, solutionshave:

previously been alluded to but it is WOl'th; repeating thatthey are inexpensive and much easier to use than are adhesives containing a volatile solvent.

Having thus. described the inventiomwhat is claimed is: 1. A method of making an open-meshtrayon fabric, comprising extruding viscose into an acid spin bath to forma regenerated cellulose yarn strand, stretching the.

strand to orient the molecules and impart strength to the yarn, washing the yarn,,applyin'g an adhesiveto the. yarn,

packaging the yarnwhile Wet, maintaining the packaged;

yarn in a highly humid atmosphere to prevent drying, disposing a plurality of suchv yarns While. wet in overlapping relationship to provide an openemesh fabric,

tautening the fabric, and holding thefabric taut while it isdryingto thereby stress the yarnand reduce the extensibility of the fabric. I

2. Amethod of making a non-woven open-meshrayon a holding the fabric taut while. it is drying "to thereby stress the yarn and reduce the extensibility of the fabric.

3. A method of making a non-woven rayon fabric, comprising extruding viscose into. an acid spin bathto form a regenerated cellulose-yarn, strand, stretching the strandto. orient the, molecules and impart strength to the yarn, releasing the tension on the strand, washing the.

strand, applying an aqueous adhesive liquidv to the strand, collecting the. strand while wet; into a plurality of packages, withdrawing strands from the packageswhilev wet and disposing the same in overlapping relationship to provide a non-woven fabric, stretching theyfabric in a manner to tension, all the strands thereof to reduce the extensibility of the fabric, and maintaining the fabric in its thus stretched condition untildry.

4.: A method of makng an open-mesh rayon fabric,

comprising extruding; viscose into anacidaspin bath to forrna regenerated cellulose strand; stretching; the strand to orientthemolecules and impart strength to the strand,

washing the strand, applying an aqueous adhesive liquid.

tothe, strand, collecting the strandiwhile-wet into aplurality of packages, withdrawing a plurality of strands from the packages while Wet and disposing the, same in.

overlapping relationship to form an open-mesh, nonwoven fabric, stretching the fabricto reduce the extensibility of the yarn, and drying the fabric while in its.

stretched condition.

References Cited in therfile ofthis'patent UNITED STATES PATENTS 2,874Q729 Ball -s Feb. 24, 1959 FOREIGN PATENTS Great Britain May 23, 1946, v

Claims

1. A METHOD OF MAKING AN OPEN-MESH RAYON FABRIC, COMPRISING EXTRUDING VISCOSE INTO AN ACID SPIN BATH TO FORM A REGENERATED CELLULOSE YARN STRAND, STRETCHING THE STRAND TO ORIENT THE MOLECULES AND IMPART STRENGTH TO THE YARN, WASHING THE YARN, APPLYING AN ADHESIVE TO THE YARN, PACKAGING THE YARN WHILE WET, MAINTAINING THE PACKAGED YARN IN A HIGHLY HUMID ATMOSPHERE TO PREVENT DRYING, DISPOSING A PLURALITY OF SUCH YARNS WHILE WET IN OVERLAPPING RELATIONSHIP TO PROVIDE AN OPEN-MESH FABRIC, TAUTENING THE FABRIC, AND HOLDING THE FABRIC TAUT WHILE IT IS DRYING TO THEREBY STRESS THE YARN AND REDUCE THE EXTENSIBILITY OF THE FABRIC.