US2328109A - Divisible paper web - Google Patents

Description

Patented Aug. 31, 1943 DI'VISIBLE PAPER WEB Oscar T. Thompson, Neenah, Wis., assignor to International Cellucotton Products Company, Chicago, Ill., a corporation of Delaware i Application May 16, 1940, Serial No. 335,543

4 Claims.

'I'he invention relates to improvements in divisible paper Webs, and its principal object is to provide a tearing line across a paper web, of such form and arrangement that a length of the web may bereadily separated or torn from the remainder ofthe web while, at the same time, the continuous web as a whole may be handled ywith facility and without serious difficulty due to breakage at the points of weakness represented by the tearing lines.

It is customary to furnish such articles as toilet paper, towel paper and certain other grades of paper in roll form, the roll of paper throughout its length being divided into sections' which are integrally connected together as parts of a continuous web of uniform width and of indenite length, weakened lines to facilitate tearing being provided at the boundaries or lines representing the end boundaries of the respective sections. It is quite desirable from the standpoint of convenience that the end portion or section of the roll should be capable of being torn from the body of the roll with facility Without danger of having the tear extend to any point beyond the desired tearing line, as it is very annoying to attempt to pull off the end section from the roll and nd that the paper is torn at some intermediate point rather than at the tearing line.

Heretofore, it has been the practice to form the tearing line by interrupting the continuity of the sheet for spaced distances along the tearing line, so as to leave the sections still connected together by integral bonds constituting undisturbed or unweakened portions of the continuous web, so that the weakened line comprises a series of aligned integral paper bonds each separated fromits adjoining bond by an opening or interruption in the continuity of the sheet. Such interruptions of the continuity of the sheet, in the zones intermediate the bonds` may be eiected by a cutting operation embodying the complete removal-of denite areas of paper, or the paper at that point may be sheared without removal of material. Ordinarily the shearing method is preferred, in which case the shearing is usually effected by multi-toothed combs or blades projected through the sheet while the latter is supported at either side of the tearing line. In such cases, it has been the practice to make the bonds of substantially equal width and also to make the spaced zones of interruption likewise of equal length, and with such an arrangement it has been necessary to effect a compromise between the conflicting requirements of a web or sheet which is readily tearable at the tearing lines only. but which will not be so fragile as to be difficult to in number, the web is too fragile, whereas, on the other hand, if the bonds are made wider and greater in number, the sheet has a tendency to tear at points other than along the tearing line.

I have made the discovery that the margin of safety between such conflicting requirements can be very materially, in fact enormously, increased if bonds of proper width are properly located along the tearing line, and I have found that, to this end, the collective center of the center of gravity of the bonds on either side of the center line of the web should be substantially closer to the center line of the web than to the side edge thereof. An explanation of such a phenomenon and formula possibly resides in the fact that, according to my experiments and discoveries, and particularly in the case of tissue products to which my invention is especially applicable, the web has considerable elasticity in the direction of its length, which, for some reason, seems to make it necessary to provide extra strength in the middle zone of the web as compared with the zones at the edge of the web.

A preferred way of using my discovery and invention in the manufacture and packaging of toilet paper will now be described.

In the drawing accompanying my application:

Fig. 1 is a diagrammatic view of the apparatus used for making toilet paper rolls from a main or parent roll of large size;

Fig. 2 is a plan view of one form of the combs or perforating devices which are employed in forming tearing lines in the paper in accordance with my invention; and

Fig. 3 is a plan view along the line 3-3 of Fig. 1.

In the drawing, I0 represents the parent roll of toilet paper or similar tissue which ordinarily `is long enough on its face to supply a web a plurality of times wider than the width of the merchant rolls II. The wide web I2 is directed between a presser or idler roll I3 around which the paper travels for a portion of the circumference of the latter. In leaving the surface of the anvil roll I4, the paper web I2 passes underanother idler roll I5 and from there through the usual rotary slitter knives I Ii and I'I arranged on shafts I 8 and I9, the pairs of which are spaced apart at the proper distance to slit the wide web into narrow webs of the required width, a pair of such slits being indicated at 20 and 2I in Fig. 3.

At properly spaced points in the periphery of the anvil roll I 4, in the usual manner there are provided openings in the form of channels 22, the centers of these channels 22 being spaced apart a distance equal to the length of the web secwind into a compact roll or of insuflicient tions. i. e. a circumferential distance equal to strength to rotate the roll on its spindle when the distance between the tearing lines 23 and 24 the end is pulled by the consumer in actual serv- (see Fig. 3). y

ice. If the bonds are too narrow and too few These channel-established openings 22 are equi-spaced around the periphery of the circumference of the anvil roll I4, the shaft 25 of which is synchronized with the shaft 26, both shafts being positively driven. On the shaft 26, there are ilxedly arranged a series of spiders or Webs 21 having rims 28, and the rims 28 are made with flanges 29 extending along the faces of the rims 28 so as to form supports for the perforating combs 30, these perforating combs 30 being bolted to the flanges 29 by means of cap screws 3|.

The distance of the combs from the center of the shaft 26 with which they revolve is such that, when the shafts 26 and 25 revolve in unison at a fixed ratio of 2:3, there being 50% more channels in the anvil roll I4 than there are sets of combs, the combs will register with the channels 22 in the proper manner and effect the desired perforation or interruption of the continuity of the sheet Wherever the teeth 32 of the combs engage the web.

It will be observed that, in the particular embodiment herein shown, there are slots cut into the edge of each of the combs 30, which slots obviously do not have any eect upon the continuity of the sheet, and thereby provide bonds which, in the drawing Fig. 3, are indicated at 33, 34, 35, 36, 31, 36', 35', 34' and 33'. These bonds are not of the same width, nor do they have a uniform spacing, as in the case of the prior art paper rolls with which the art is familiar. Instead of that, such bonds are arranged so that the collective center of gravity of the bonds 33, 34, 35, 36 and half of the central bond 31, assuming that the mass f a unit Width of the web is uniform, is located a substantial distance nearer to the center line 38 of the web than to the edge 20 of the strip. 'The same condition exists in respect of the collective center of gravity of the bonds 33', 34', 35', 36' and half of the bond 31 lying below the center line 38, which center of gravity is materially closer to the center line 33 of the strip than it is to the edge 2|. Such an arrangement of bonds is effective to carry out the purposes of the invention as above set forth.

The bonds or uncut parts 33, 34, 35, 36,-31, 36', 35', 34' and 33 are separated by variable length cuts 40, 4|, 42,43, 43'. 42'. 4l' and 40', as shown. It will be seen that these cuts have serrated edges and are symmetrically disposed 0n opposite sides of the center line 38 as are the bonds or uncut parts 33, 34, 35, 36, 31, 36', 35', 34 and 33'. The outermost cuts 40 and 40 are substantially longer than the innermost cuts 43 and 43. and the intermediate cuts 4I, 42, 4|' and 42' are progressively shorter towards the center line 38 of the i web.

In actual practice, in applying the invention to toilet paper rolls which are 41/2 inches in width. I may use nine bonds of about s", of an inch, the spacing and length of the cuts between the bonds being graduated from a spacing or length of of an inch at the margin of the sheet down to about 1A of an inch at the middle of the sheet and, in such case, it is not necessary to make any material variation in the width of the bonds. On the other hand, the spacing and length of the cuts between the bonds may be substantially equal across the web while the width of the bonds is increased from the outer edges of the Web towards the center line thereof. However, I find it of some advantage to vary both the lengths of the cuts and the widths of the bonds and to make the side bond 11e of an inch in width and the middle bonds as wide as l; of an inch or even somewhat wider in certain cases, the widths of the intermediate bonds being, of course, graduated also in accordance with the formula of my invention. It will be manifest that either or both of such arrangements may be employed in order to effect the purpose of the invention.

I claim:

1. A paper web adapted to be rolled up and to be used by tearing off short pieces from the free outer end of the roll, each pair of adjacent short pieces being separated by a plurality of spaced apart cuts extending in a line from edge to edge across the web at substantially right angles to the length of the web and marking off the short pieces into which the web is adapted to be torn, the ends of the cuts being separated by narrow uncut parts, said uncut parts in each of said lines of cuts being symmetrically disposedon opposite sides of the center line of the web, and the uncut parts in each line being progressively narrower from said center line towards each edge.

2. A paper web adapted to be rolled up and to be used by tearing off short pieces from the free outer end of the roll, each pair of adjacent short pieces being separated by a plurality of spaced apart cuts extending in a line from edge to edge across the web at substantially right angles to the length of the web and marking off the short pieces into which the web is adapted to be torn, the ends of the cuts being separated by narrow uncut parts, said uncut parts in each of said lines of cuts being symmetrically disposed on opposite sides of the center line of the web, and the cuts in each line thereof being progressively longer from said center line towards each edge.

3. A paper web wound upon itself into a roll and provided with transversely extending lines of weakness spaced longitudinally of the web for facilitating tearing of predetermined lengths of the web from the end thereof, said lines of weakness being formed by cutting the web so as to provide between each side edge of the web and the longitudinal center line thereof, a group of transversely spaced bonds, the bonds of each group being of progressively decreasing width from adjacent the center line of the web toward the edges thereof, and said bonds being spaced by cuts in the web, the cuts being progressively longer from adjacent said center line towards said edges, said-cuts and bonds being disposed symmetrically on opposite sides of said center line, and one of the bonds of each group being located at the side edge of the web so as to maintain continuity of the web at its side edges.

4. A paper web wound upon itself into a roll and provided with transversely extending lines of weakness spaced longitudinally of-the web for facilitating tearing of predetermined lengths of the web from the end thereof, said lines of weakness being formed by cutting the web so as to provide between each side edge of the web and the longitudinal center line thereof, a group of transversely spaced bonds, the bonds and spaces in each line of weakness being so arranged that said lines are stronger adjacent said longitudinal center line than they are adjacent the side edges of the web, one of the bonds of each group being located at the side edge of the web so as to maintain continuity of the web at its side edges.

OSCAR T. THOMPSON.

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