US2442279A

US2442279A - Elastic thread

Info

Publication number: US2442279A
Application number: US601577A
Authority: US
Inventors: Sterling W Alderfer
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-07-01
Filing date: 1945-06-26
Publication date: 1948-05-25
Anticipated expiration: 1965-05-25

Description

May 25, 1948. s. w. ALDERFER 2,442,279

ELASTIC THREAD Original Filed July 1, 1944 2 Sheets-Sheet 1 Qwumvbov TEQUNG w ALDERFER m fgl ma www@ Summa/lit' May 25, 1948. s. w. ALDERFER ELASTIC THREAD Original Filed July l, 1944 2 Sheets-Sheet 2 SWW/who@ 515ml Na 'w ALDERFER Patented May 25, 1948 ELASTIC THREAD Sterling W. Alderier, Akron, Ohio l Original application July 1, 1944, Serial No.

543,132. Divided and this application June 28, 1945, Serial No. 601,577

4 Claims.

, l This invention relates to new and improved elastic thread, cords, cables orY the like and to fabrics made therefrom or incorporating such elements. The products covered hereby have new and useful properties.

Heretofore it has been diiiicult to make an elastic fabric which is easily stretchable or, as

it is termed in the trade, a lazy" fabric. Fabrics oi this type are especially desirable in the manufacture of articles of apparel which should have (therefrom. Because of the substantial tension which is ordinarily maintained, the finished fabric has a very strong tendency to contract. The desired property of a mild tendency to contract, just sufficient to cause the garment to cling to the body without exerting excessive constriction, is impossible or dimcult to obtain under existing processes for the reasons stated.

One of the objects of the invention is to provide a lightly tensioned elastic thread or cord from which a garment or tape may be fabricated on standard weaving, braiding or knitting machines without the diiiiculties due heretofore to the elongation of such a thread or cord. It is, therefore, possible by practicing the invention to secure a moderate elasticityin a finished thread or in a garment made on the ordinary covering and knitting or weaving machines.

This application is a division of my prior copending application, Serial No. 543,132, filed July 1, 1944, now Patent No. 2,427,334, dated September 16, 1947. This patent is directed to the new processes for making the elastic thread or fabric, while the present application is directed to the completed products. In order to make the present invention clear and understandable it is deemed advisable to describe processes by which the products may be made, although it may be conceived that other processes might be devised to secure the resultant materials. It is therefore, not to be considered that the subject matter of the present application is necessarily confined to products manufactured by the processes herein described.

In the accompanying drawings and description, there are shown several forms of the invention, and several methods which may be employed, but it will be understood that the invention is not limited to the specific materials, details or steps shown, for, when the principles are understood,

2 it is possible to devise modifications or improvements thereon without departing from the basic principles of the invention.

The products may be made by attaching or depositing the rubber constituent of the thread upon a backing or foundation which has some ability to elongate, but which will reach its maximum elongation at a point where the rubber portion oi the composite material has reached the determined tension which will give desired elasticity to the finished thread or garment. There is little or no recovery in a sheet of this material after it has been stretched or orientedf so that the rubber is held in tension by the backing material. As a, result, when the composite rubber and plastic thread is covered with any suitable textile material, the thread has no stretch or an easily controlled stretch. Also, when the threads are placed in the knitting or weaving machine, this property of the thread permits the machine to operate with the ease and at speeds which are obtained in the manufacture of non-elastic fabrics.

When the thread is covered, if an elastic thread is the finished product, or when the fabric is completed,v the thread (or fabric) is preferably put through a finishing bath to remove the dirt, oil or sizing which may be found thereon. Water soluble backing material will dissolve in the bath leaving a. soft, mildly elastic fabric or thread. While a water soluble backing is preferred because it is readily destroyed in the usual nishing bath, any other fugitive backing may be employed with an appropriate after treatment which will remove the plastic material but is non-deleterious to the rubber or covering material.

In some aspects of the invention it may be desired to use as the backing material a non-fugitive plastic which has a certain amount of stretch and ability to move with the rubber element of the thread or cord. A backing of this type will be retained in the finished thread or fabric, and while it will perform the same function of giving to the thread the firmness which is so desirable for the covering and knitting or weaving operations, it does not unduly aect the elasticity of the finished product. An advantage of this form of the invention is that if the rubber element should be cut or broken during the subsequent manufacturing operatons, the rubber thread will not retract and lose its elastic properties as is a common fault in ordinary elastic fabrics, but will be retained in position and, therefore, the elastic effect of the thread will be retained on either side of the break.

The composition of the backing sheet is determined by a number of factors.

readily water soluble. The backing material should have the ability to stretch or elongate and to reach its maximum elona'ation at the point where the desired elongation or tensionupon the rubber is reached. There have been developed recently a number of plastics or synthetic resins which will answer these requirements, and while it is not wished or intended to limit the invention in any manner to one material or group of materials. it has been folmd that polyvinyl alcohol and its derivatives will operate satisfactorily.

For the rubber constituent of the thread it is preferred to employ a natural or artificial waterdispersion of rubber. Natural latex is admirably. suited for the purpose as are the water-dispersions of natural or synthetic rubbers. It is also possible to employ solutions of natural or synthetic rubbers or rubber-like material in any suitable vehicle. The rubber'contains the usual -compounding and vulcanizing ingredients, or a vulcanized rubber latex or rubber dispersion may be employed, in which case the rubber layer does not require further vulcanization.

When the backing employed is water soluble and the rubber constituent is a water dispersion of rubber orsimilar elastic material, it is essential to protect the backing from the dispersion. and for this reason the side of the backing which is to receive the rubber will receive a light coating which will give an interposed layer of a water resistant adhesive which will adhere to the backing layer and also to the rubber. A cement sultable for this purpose may be made from any of the well known rubber hydrochlorides. The material sold by du Pont under the trade name RDL, the composition of which is maintained as a trade secret, may also be employed. If some other vehicle or solvent for the rubber is employed which will attack the backing layer. an appropriate change in the composition of the intermediate adhesive will be made.

In certain forms of the'invention an insoluble or non-fugitive backing is employed. In such cases the backing material may be nylon" or one of the several polyvinyl chlorides, vinylidene chlorides, rubber hydrochloride or any other orientable film, and in the use of any of these materials, it is not necessary to interpose a layer of adhesive.

Having set forth the invention in general terms, practical applications thereof and means for making the same are shown in the accompanying drawings in which:

Fig. 1 is a diagrammatic showing of the rst several steps in a process in which a water soluble or other fugitive backing is employed and in which the rubber is applied as a water dispersion.

Fig. 2 shows the steps employed for the formation of the rubber thread when the backing material is elongated before the composite sheet is out into threads.

Fig. 3 shows the twisting and covering of the thread on what is known as an up-twister.

Fig. iis a cross-section on the line 4-4 of Fig. 1 showing the sheet from which the threads are cut.

Fig. 5 is a view showing the thread separated into its constituent parts.

Fig. 6 is a view of an ordinary cross-woven fabric made from the thread, one of the threads being unraveled. In this view the fabric is deemed to have been treated so as to remove the backing layer.

Fis. 7 is a cross-section of one modification of employed.

Flaneis aviewshowingafabricmadefrcmthe thread of I'lg. 7.

Fig. 9 shows a modldcation of the process after the sheet of backing and applied rubber has been assembled.

Fig. 10 shows the second step in the liedied process.

Fig. 11 shows thetwisting and covering of threads, this view showing the stretching or elongation of the composite threads as taking place concurrently with the twisting and covering operations. In this view the thread is twisted and covered on a so-called down-twister."

Fig. 12 is a detail section on the line I-II of F18. 1l.

Referring to Fig. l, a sheet of polyvinyl alcohol or otler soluble or fugitive material is indicated at I asitispassedfromasupplyrolllovera guide roll 3 and thence to a pair of stretching rolls 4. The rolls 4 are preferably driven at a substantially accelerated surface speed so as to stretch and partially orient the material, and to facilitate the elongation of the'material the roll 3 and the rolls 4, or either of them, may be gently heated to soften the backing sheet. While any suitable degree .of stretching may be performed at this point, a polyvinyl alcohol sheet or film which can be elongated l000% before its oomplete orientation, i. e.. when no further stretch can be imparted'thereto, will be elongated say 500% between the rolls 3 and 4. It is possible to omit all stretching during this stage in the vprocess and perform all of the stretchingof the backing at a later stage in the process.

From the rolls 4 the material in its partially stretched condition has applied to one side thereof a water-resistant adhesive l. The applicator roll 1 indicates one means by which this operation may be performed. After the intermediate or protective layer is applied to the backing. it is ready to receive the coating or layer of rubber or similar elastic material which is to form the body of the thread. In the drawing a simple form of spreader blade l is illustrated as merely A an example of one means which may be used for l the purpose. -Behind this blade l is a bank of elastic material in the form of latex or rubber dispersion which is spread over the protective adhesive coating t'o a thickness determined by the desired gauge or thickness of the nished rubber thread. In lieu of the spreading operation, the rubber may be applied by any suitable means, such, for example, as by caiendering.

From the rubber application point, the sheet of backing with its overlying rubber layer now passes into a. heated chamber Il where the layer of rubber is dried and vulcanized. As the sheet, now carrying the vulcanized rubber layer, issues from the drier-vulcanizer it may receive a coating of soapstone or other material to render its surface non-adhesive. A dusting device for this purpose is indicated at Il. The sheet is then rolled up as shown at l2 and the roll permitted to stand -until the material is cooled and sets.

A roll of the material i2 is then transferred to a location for the next series of steps. From the roll I2 the material is conducted to pairs of stretching rolls I 5 and Il which may be heated and are driven at progressively accelerated speeds to impart the final stretch and orientation to the backing material. This operation also stretches the rubber to the desired degree. The distribution of the total elongation of the backing be- .5 y tween preliminary stretching rolls 3 and I and the nal stretching rolls I5 and IB will beoptional, depending upon the amount of elongation required to bring the backing to complete or substantially complete orientation and also upon the degree of stretch or tension which it is desired to impart to the rubber. In lany event, the

amount of stretch which is imparted to the composite sheet between rolls I5 and i6 should be considerably under the elastic limit of the rubber so as to impart the light, easy or lazy tension t the rubber constituent of the thread in orderV the fact that the backing layer has been eloni gated up to the point where little or no further elongation is possible, or, in the terms commonly used in this connection, the backing layer is said to be fully oriented, i. e., the molecules have rearranged themselves so that no further elongation is possible. However, if the thread is relaxed, the rubber will tend to contract, throwing the thread into a series of closely spaced spirals, but as the oriented backing cannot contract, the rubber will remain in longitudinal tension. The thread will always assume a spiral formation with the backing layer on the outside of the rubber.

This property of the composite thread to assume a natural twist or spiral is a substantial merit of the thread because the twisted or spiral rubber is under compression. A rubber thread made from such a twisted rubber core, has much superior aging qualities because the twisted rubber is compressed laterally, although it is`sti1l under longitudinal tension. The fact that the backing layer is on the outside surface of the thread will protect the thread from the air and reduce or retard oxidation. The surface of therubber which is next to the backing and at which point the rubber is under maximum tension is completely shielded from the air.

It will be seen that as the thread as now constituted is firm and has little or no stretch or elongation because of the presence of the oriented backing layer, it may be used in any standard type of textile machine with great ease and facility for the operator does not have to make any allowances for stretch in the thread. It may be placed directly in a loom or knitting machine if'bare rubber thread is to be used. However, it is generally preferred to cover a rubber thread with a jacket or winding of cotton, rayon, nylon or other textile material before incorporating it in a garment.

For covering the material, the composite thread of rubber and backing may be placed on the beam or spools of an ordinary covering machine and one or more layers of the textile material wrapped about it. The covering operation may be performed while the thread is held in straight or taut condition. It is preferred, however, to twist the rubber thread during the covering.l operation so as to impart a certain degree of added elasticity to the thread. A device for this purpose is shown in Fig. .3.

ard iup-twis covering machines. The package is rotated as shown and the composite thread passed 25, this operation imparting a twist to the thread. The amount of the-twist may exceed the natural twist, in lwhich case the rubber will be placed under increased compression. This is an especially valuable attribute of the invention, as rubber under compression has much superior aging qualities. From the rolls 25 th'e twisted thread passes through the center of the rotating package 26 which carries'one or more strands of the covering material which are wrapped in close covering spirals over the twisted thread which-now becomes the core of th'e covered elastic thread, now

indicated by the numeral 28. The outer wrapping maintains the compression imparted to the rubber during the twisting operation. It will be observed that the direction of twists impartedby the `operation of the

packages

22 and 26 are in opposition so that a substantially balanced or non-kinking thread is obtained, The thread thus obtained h'as a certain degree of give or elasticity due to the fact that the rubber and its backing layer are twisted in spiral form. The amount of stretch of which this thread is capable is dependent upon the extent to which the spirals of the backing material may straighten out. If avery tight twist with a high order of twists per inch is imparted to the composite core at 22-24, the amount of elongation may be quite small, butif the twist is on a longer spiral with less twists per inch, the possible elongation is greater. As the rubber is compressed within the spiral outer backing layer, there is always a point at which no further stretch can be imparted to the composite thread. 'I'he controlling factor for the elongation is the oriented and non-stretchable backing layer or ribbon which will give a total elongation only to the extent to which the spirals of the backing may spread apart before they reach their limit. The rubber is still under a rather light tension when the composite thread has reached the limit of its extensibility.

What has, therefore, been accomplished is a thread shown in Fig. 5 which has exactly the same 'capacity for elongation as a highly tensioned rubber thread which may be used successfully and practically on standard elastic knitting, weaving or braiding machines. However, when the backing is eliminated, as has been stated, the rubber constituent of the thread will contract and there is, therefore, obtainable a softly yielding piece of elastic goods or fabric.

If, as suggested above, the twisting operation is omitted, the resultant composite thread will have a reduced elongation owing to the presence of the substantially non-stretchable backing, but when the backing is eliminated th'e latent tension in the rubber will be released and the thread will contract, giving a mild elasticity to the product. As the rubber is not twisted in this form, the thread will not have as much elasticity as in the preferred form.

In Fig. 6 is illustrated a simple. square woven fabric as an example of the product after the backing h'as been eliminated. This fabric will be considered to have been woven from threads 28 on an ordinary loom. After the fabric was completed, it was given the usual water bath orscouring treatment to remove dirt, oil, sizing and other extraneous matter and the water has attacked the soluble backing i and that is now completely eliminated. The material is an elastic fabric with through the well known flyer 24 to rolls a contractive property imparted by the tensioned and twisted rubber threads.

While for many types of fabrics it may be desirable or advantageous to remove the backing layer. in other fabrics this may not be so desirable and in that case any of the non-soluble, but orientable materials may be employed.

In Fig. 7 the rubber layer or constituent is indicated at 9 and the backing layer at l. In making this type of fabric or thread the same procedures are employed as in the one just described in full, except that the protective adhesive 6 is not necessary. The degrees oi' stretch re- 'quired to give th'e preliminary and the ilnal orientation will be determined from the character of the material and the results desired, it being desirable always to impart an elongation after the application of the rubber layer which will give the desired tension to the rubber constituent of the thread. As the backing is not eliminated, the amount of elasticity or stretch in this finished thread or fabric will be determined by the extent 8 celerated surface speed so that the composite ma- 3 terial is given the stretch which is necessary to v rolls 44 and the spindle the thread passes through to which the spirals o! the backing layer may be elongated before the limit of extensibility is reached.

The process of manufacture shown in Figs. 9 to 12 diners from that shown and described hitherto mainly in the fact that the stretching of the composite material is performed afterit is cut into threads and simultaneously with the twisting and covering or the threads.

In Fig. 9 a sheet of backing material and rubber is indicated at 30, this sheet having been made by the procedure illustrated in Fig. 1 or by any of the modiiled processes, The backing material may have been given a preliminary and partial stretch or it may be without any elongation lat this point. The material is ilrst cut into a series of tapes or relatively wide ribbons by the slitting knives 32 and thence passed to a pair of guide rolls 33 from which the ribbons or tapes are wound upon a plurality of storage spools 34. The rubber at this point is not under any tension whatever and the spools may be stored for av considerable period without deteriorationrof the rubber, and may be shipped to the thread maker in this condition.

For the manufacture of the finished thread a ribbon or tape is led from the roll 34 through a final slitter 35 where the composite material is cut into the narrow thread form, all of the threads being wound up on a beam indicated by the numeral 38. This beam is then mounted in a'covering machine.

The twisting and covering operation is performed in a. down twister and as shown diagrammatically in Fig. 11, it being understood that the drawing is illustrative only and that the number of threads carried on a beam is limited only by the number of twisting units which may be carried on one twisting machine.

From the beam 36 each thread I8 is led to a pair of guide rolls 39 and thence to a group oi rolls by which the thread is stretched to complete the orientation of the backing and impart the desired tension to the rubber element of .the composite thread. This group comprises a pair of drawing and guide rolls 40 and an intermediate roll 4I which may be heated moderately to facilitate the orientation of the backing. Preferably this roll 4i extends the entire length of a twisting unit. From roll 4| the thread passes to a second pair of rolls 42. The rolls 40 and 4| are preterably driven at the same suri'ace speed as the drawing rolls, but the rolls 42 are driven at an ac a spool or package 4i containing the covering material 41 which passes through the ilyer Il and is wrapped about the thread, it being noted that the twists imparted bythe spindle 4I and the package 48 are in the reverse direction as indicated by the arrows. The covered thread passes through guide rolls 50 and to a travelling eye or laye r\5| which winds Athe twisted and covered thread upon the rotating spindle.

The method illustrated in Figs. 9 to 12 has certain advantages for commercial practices. It is also advantageous because the order of the ilnal thread slitting and stretching steps makes it possible to secure much smaller gauge threads than is practical where the stretching precedes the final cutting operation.

For the manufacture of very fine rubber threads a. still further variation of the process may be employed. In such a case the backing material is coated with a layer of unvulcanized rubber which is dried and then the composite sheet of backing material and unvulcanized rubber is stretched which orients the rubber and the backing sheet simultaneously. While unvulcanized rubber will not orient uniformly, if stretched by itself, the presence of the uniformly orientable backing will cause the rubber to orient uniformly. This operation will give a rubber film of extreme thinness. The composite sheet will then be vulcanized. If desired Ithe material may be given a fur-ther orientation after vulcanization either in sheet form or after the sheet is cut into threads. This will reduce the size of the threads still further.

It will be understood tha-t where the term rubber" is used, the intention is to cover any natural or synthetic rubber or elastic rubber-like material in any form.` By the term orientable is meant any of the synthetic resins, vinyl compounds or any of the numerous plastic materials which have been developed in the arts which have the property of elongating to a denite or ilxed degree, a result which is commonly attributed to an orientation of the molecules of the material. This property of stretching or orientation is frequently aided by the application of heat. By fugitive backing is meant a layer or sheet of this type oi' material which is soluble in a mediumwhich does not ailect the elastic constituent or the covering material employed. Ordinarily the fugitive material will be one which is water soluble so that it may be readily removed by merely washing the thread or the completed fabric in a water bath, although other materials may be eliminated by other non-deleterious treatments. It will also be appreciated that while it is desirable to orient the backing partially so as to give a light degree of tension to the rubber when the backing is fully oriented, this does not exclude performing all the orientation after the rubber layer is applied. The orientation may be carried to the limit or it may approach that degree. It will, therefore, be understood that the term orientation" or orienting is intended to cover both partial and complete orientation. Where the term threads is employed, it will be understood to cover ilne and heavy threads, cords and cables, and "fabrics include all types of textile material.

What is claimed is:

1. A laminated thread comprising a ilat ribbon of polyvinyl alcohol in a. condition of permanent elongation and orientation, and a lm of rubber adhering to a. surface of the ribbon and maintained in a state of longitudinal tension by the ribbon.

2. A laminated thread comprising a flat ribbon of polyvinyl alcohol in a condition of permanent elongation and orientation, and a dried iilm of rubber deposited from an aqueous dispersion thereof adhering to a iiat surface of the ribbon. said rubber nlm being maintained in a state of longitudinal tension by the ribbon.

3. A laminated thread comprising 9, llat ribbon of a water soluble polyvinyl resin in a condition of permanent elongation and orientation, a water resistant coating on a at surface of said ribbon, and a dried film of rubber deposited from an aqueous dispersion thereof adhering to the coated surface of the ribbon and held in a state of longitudlnal tension by the ribbon.

4. .An elastic thread comprising a long narrow ribbon of polyvinyl alcohol in a condition oi permanent elongation and orientation, and a illm of dried, vulcanized rubber deposited from an aqueous dispersion of rubber on one surface of the ribbon, said rubber being in a dormant state oi' tension in which i-t is held by the ribbon.

STERLING W. AIDERFER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS