US 2331955 A
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' trary is true and the whole lore and attitude of Patented' Oct. 19, 1943 UNITED STATE-S PATENT OFFICE y Gubert n. Beebe una Archie w. xeon, Auburn,l
N. Y., assignors to Columbian Rope Company. Auburn, N. Y., a corporation of New York` Application February 24, i942, serl'ui No. 4am comme (ci. .ti-14o) This invention relates to improved thread.
It is usual for threads and other nlaments, useful for tensile purposes, to be spim or otherwise formed from substances stable in the presence of water' and, to this end, every effort is made to im- 5 prove their resistance to water, so that they will retain their utility even when immersed or otherwise exposed to water. However, it appears that special applications occur wherelthe conthe textile and cordage industry toward waterbecome pointless. For example, it is highly desirable that paper bags be closed by thread which is dispersible in water and in materials used in paper pulp beaters. For instance, where the bag i5 is used for packaging sugar and its closure is in the form of a cotton thread, great care has to be exercised in preventing particles of the thread falling in the mixture in which the sugar is used.
bag into the mixture, particles of the'thread drop into 'the mixture and. as the cotton will not disperse, additional straining operations are required forv removing those particles before the mixture can be used. It the contents of the 25 paper bag are to be used. in the manufacture of paper, the bag with its contents can be Placed bodily in the paper pulp stack if the closure means are dispersible in the stock, but not if a cotton l thread has been used for closing the bag. Also. if 30 discarded paper bags are to be reclaimed for subsequent manufacture of paper., their value is greatly depreciated# they have a cotton thread closure. Paper bags sewn with cotton thread have a comparatively small reclaim value, this 35 gure running from eight tofifteen dollars a ton, due to the necessity oi using manual labor in t removing the insoluble cotton sewing thread, as thev latter must be removed ,before the reclaimed bag can`be deposited in the paper'pulp'jstock. 49,
Resort has been had to closing paper bags by pasting, but 'this is not -commercially feasible," at least in certain types of bags, because suchf.. closure meansis too insecure ior a large number ofuseswhich reduire thev safety and extra.;v l(
strength of sewing. VIt has also been proposedto 1 use a sewing thread madeof paper, butthis, also, is not entirely satisfactory for reasons hereinafter set forth.`
One object of the present invention is to over- 5 come the above difficulties by providing a sewing thread for closing paper bags which, together with the bag, will be dispersed, or, if desired, I
ter or in materla1 used in istV ious sugars, glycerol can be used.
actually dissolved in 10 neue ef e polyvinyl alcohol which is dispersibie in water. Various types of this material are available and, hence, the invention is not limited to any one particular type, except that itmust be capableof being rather readily dispersedA in water. In the preferred embodiment of the in` vention, one or more ends or lengths of polyvinyl valcohol are used in the thread'and the ends or threads subjected to a controlled stretching operation, as this increases the tensile strength of the Oftentimes, while emptying the sugar from the 2o [ends and thread formed therefromx In the accompanying drawing Figure l is a diagrammatical -illustration oi Fie. 3 is e similar illustration' of mechanism for i stretching theV ends or threads. A v
In the preferred embodiment oi the invention,
the polyvinyl alcohol is produced in film-'like strips which are individually twisted' into ends and the finished thread is formed oi one' or more of these ends. The size of the end will, of course, depend upon the thickness and width of the strip l' 'from which the end is formed and the number of ends used in forming the thread will, in turn.
depend upon the size oi the ends and the size desired for the iinished thread. If 'a comparativelyfine thread vis desired, it isv possible to make the end large enough so that a single -end may.
serve as the Where a large thread is t t desired, a' number of ends ban be plied or twisted t together. The twisting of the nlm-like strip can beccomplished while the strip .is dry 0r with or, steam ver a suitable spinning solution kknown type oi' twisting frame such as used. for twisting paper. AThe number of turns Per twist 'maybe veiledI between renier wide limits and the twisting may -bedone with or without v a tubing device. The several lends can ,be plied en usual twisting vequipment used in'tiie textile industry.. The spinning or twisting can be accomplished while the material is dry or with the use of steam or other heat or moisture source. Suitable spinning solutions,.such as starch, var- In lieu of twisting the nlm-like strips to form the ends, the polyvinyl alcohol can be extruded in the form of continuous filaments, one or more stretching them as a group after plying. However, as the submoiecular structure of the present material is such that a single filament can be stretched and its tensile strength thereby increased to a point where it alone can serve as the thread, the necessity of plying is eliminated. lt is also possible to stretch the in ilm :torni or before the twisting operation.
The present thread is ci ampie strength for the purpose for which is intended and its principal virtue is its dispersibiiity in water and materials used in ordinary paper pulp stocks under the action of a beater roll, 'Jue to this feature, use of the present thread in paper bags has more than trebled the'reclaim value of the bags, paper manufacturers being willing to pay a minimum price of thirty to thirty-live dollars a ton for paper bags closed with the present thread, as compared with the minimum of approximately ten dollars a ton paid for the bags sewn with cotton thread. The bags, with `the ypresent thread, can be placed directly in with the ordinary paper pulp stock or, in the case of sugar packaged in the bags, it is not necessary, in emptying the bag, to exercise any great ammini? of care to prevent particles of the thread falling in the mixture. In fact, where the presence of the bag is not detrimental, as in using the bag or its contents in paper pulp stock, the bag and its contents can simply be deposited in the batch oi' stock, as the present closure thread will disperse.
As previously indicated, various types of poly- Vinyl alcohol are available, but, in practicing the `present invention, care must be taken to select only those types which are water-dispersible. In some instances, it might be desirable to use a type which will actually dissolve in water, but the primary characteristic is that the particular type used must be capable of ready disintegration for regeneration purposes.
Aside from vthe property of dispersibility or solubility, the polyvinyl alcohols possess other marked advantages over such a material as paper.
Where paper is to be spun into thread, care must be had to select a paper having a high degree of spinnability. Such a paper is difficult to produce because of the tendency of the natural fibers to become arranged promisouously or at random in the sheet, whereas, the best results. s* far as concerns spinning, are obtained where te iibers are arranged substantially unidirecftional lengthwise of the paper. Such an arrangement, however, is quite difilcult to produce on a commercial basis, thus materially increasing production costs. On the other hand, the polyvinyl alcohols have no structural element comparable to the natural bers used in the manufacture of paper. Consequently, the materials proposed in the present instance possess the' desired degree of spinnability. Again, a thread of polyvinyl alcohol is considrably stronger than a. thread of like size made of twisted paper. This is especially true where the polyvinyl alcohol thread has been stretched as previously described. Thus, the present material is much to be preferred over paper because a smaller thread can be used and. naturally, the smaller thread will possess greater ilexibility which is 'a further feature that is quite advantageous in using the thread in present day high speed sewing machines. In connection with the comparative strength of the present thread and paper thread. it should also be pointed out that sizing or calender-ing or the papenwhich tends to strengthen it, is impossible, because those operations would seriously interfere with the disperslbility of the paper thread.
While the present thread has been developed primarily for use in closing paper bags, it will, no doubt, be susceptible of other uses. lit will also be understood that, while reference has been iliade to the action of the heater roll in dispel-sing the present thread, such action ci' the roll is not indispensible. The present thread will become dispersed in water without the use of the beater roll, the latter being used only to expedite or facilitate the dispersion of the thread.
The steps of twisting, plying and stretching the thread, or the ends composing the same, are shown diagrammatically in the accompanying drawing. Fig. l illustrates a. roll or coil A of the material in strip form and the strip is drawn over tensioning rods B, B, through a tube C on to a revolving iiyer or bobbin D which twists the strip into an end E. Where a number of ends are used to form the thread, they are drawn through a tube F on to a revolving flyer or bobbin G which twists them together into the thread T. For stretching the thread or eind, it is drawn from a bobbin H around capstans I, J, revolving at different speeds on to a bobbin K. The capstans J revolve at a speed higher than that of the capstans I to stretch the end or thread. As previously described, the ends may be stretched before the plying step or the thread itself may be stretched.
What we claim is:
1. A paper bag closure composed of a thread made essentially of polyvinyl alcohol extending through the wall of the bag, said thread being capable of being applied to the paper bag by sewing for Vclosing said bag, and said thread and bag both being dispersible in water under the action of a beater roll for regeneration purposes.
`2. A paper bag closure composed of a thread extending through the wall of the bag, said thread consisting of one or more ends each formed of a twisted lm-like strip of a polyvinyl alcohol, said thread being capable of being sewn into the bag for closing the latter and said thread and bag both being dispersible in water under the action of a beater roll for regeneration purposes.
3. A paper bag closure formed of a thread extending through the wall of the bag and capable of being incorporated in said bag by sewing, for closing the latter,said thread being formed of one or more extruded ends of polyvinyl alcohol, and said' thread and bag both being dispersible in water under the action of a beater roll for regeneration purposes.
4. A paper bag closure formed of a thread composed of one or more ends of polyvinyl alcohol extending through the wall of the bag, said thread being stretched to orient the polymer and capable of being incorporated in the bag for sewing to close the bag, said thread and bag both being dispersible in water under the action oz a, beater roll for regenerating purposes.
' thread being capable of being sewn into the bag to close the latter, and said thread and bag both being dispersible in water under the action of a beater roll for regeneration purposes. 6. A paper bag closure formed of a thread extending through the wall of said bag and com- 10 posed of one or more ends each made of a Vtwisted lm-like strip of polyvinyl alcohol stretched to orient the polymer before being twisted, said thread being capable of being applied to the bag by sewing to close the latter, and said thread together with the bag being dispersible in water under the action of a beater roll forregenerating purposes.
GILBERT R. BEEBE. ARCHIE W. KOON.