US2772774A - Tape roll and core - Google Patents

Description

Dec. 4, 1956 G. R. RABUSE TAPE ROLL AND CORE Filed March 19, 1953 famili! i: n m.

INVENTOR. y www e" l 5' Mm ff/Vfy rates Unite TAPE RoLL AND CoRE Application March 19, 1953, SerialNo. 343,431

2 Claims. (Cl. 206-59) This invention relates to the art of winding tapes into rolls, to improved rolls of tape wound upon cores, and to a novel tape core construction. Although not limited to use in connetcion with such materials, the invention nds particular utility in respect to pressure-sensitive adhesive tapes; e. g., cellophane tape, plastic lmr tape, etc. The yconstruction of several varieties f tape in'connection with which this invention has special utility is disclosed in United States Patents Nos. 2,177,627, issued to Richard G. Drew, and 2,559,990, issued to Ralph I. Oace et al.

Adhesive tapes, including pressure-sensitive adhesive tapes, are ordinarily sold in roll form. The stripof tape is wound uon, and supported by, a rigid core which, most frequently, is made from paper or plastic material such as polystyrene. Such cores are customarily made in two diameters, i. e., a core having a 1 internal diameter and :a core having a 3" internal diameter. The larger-size core is customarily used to support a longer rollof tape, e. g., 60-72 yards, whereas the smaller core is custom- :arily wound with a strip of tape having a length of from toV 36 yards, although shorter strips are sometimes wound on this smaller core.

One perplexing problem which has heretofore existed, particularly in respect to rolls of pressure-sensitive adhesive tape, is the problem of telescoping of the tape upon the core. This means that a lateral displacement of the turns in the roll occurs toward one side, the amount of displacement increasing outwardly from the core, so that a funnel-like effect is produced. Although the problem of telescoping is most prevalent in rolls of pressuresensitive adhesive tape wound upon a l core, it also occurs, with some frequency, in rolls of such tape wound upon 3 cores.

Telescoping occurs principally because of radial compression or squeezing of the tape upon its rigid core. The forces which cause such compression or squeezing may result from excessive tension used in winding the tape upon the core or may be created by shrinkage of the tape backing material after it is wound on the core.

Also, particularly in respect to hygroscopic tapes (e. g., cellophane tape), compressive forces within the roll result from high atmospheric humidities to which the rolls of tape may be subjected in certain localities of use. Moisture is readily absorbed by the cellophane backing of cellophane tape (through its exposed edges) and causes swelling which, in turn, causes a squeezing of the tape upon the core.

Because of the fact that adjacent convolutions of tape in a pressure-sensitive adhesive tape roll adhere to one another, they cannot slip, or adjust circumferentially, in order to relieve the pressures in the roll. Neither can those pressures be relieved by radial contraction of the tape roll, for, in most cases, the tape is wound upon an incompressible core. Corrugated (i. e., radially compressible) cores which have heretofore been used in overcoming the problem of telescoping, are rather high in cost. Moreover, such cores are not completely satisfactory when made with a 1" diameter, and have not come into wide atent " ce 2,7 72,774 Patented; Dec. .19.55

commercial use in that size. Thus, in rolls of pressuresensitive adhesive tape such as have heretofore been cornmercially sold, particularly on l cores, there has been no way for the pressures and tensions. within the roll to be relieved, except by lateral displacement 0f the Convolutions of tape; i. e., by telescoping.

lt is an object of this invention to provide a tape core which will permit the pressures built up within the roll of tape to be relieved radially to avoid the phenomenon of telescoping, which occurs when those forces are relievable only axially of the core, as in prior commercial tape rolls wound on rigid cores.

To accomplish this objective, I provide a tape core so constructed that it comes into contact with the roll of tape wound upon it only along the mid-portion of the width of that roll of tape, and not at the edges of the tape roll. In other words, when the core of my invention is wound with a strip of pressure-sensitive adhesive tape, there is a space between the edges of the innermost wrap of tape and the marginal edge portions of the core. There is no rigid core support underlying the edges of the tape roll. Thus, when radially compressive forces are created in the edge portions of the tape roll, by swelling or otherwise, the circumvolutions of tape in the roll may be displaced inwardly, toward the axis of the core, to relieve and accommodate the tensions in the roll. The phenomenon of telescoping is thus avoided.

The basic concept statedl above may be accomplished in a variety of ways. Several preferred embodiments are shown in the accompanying drawings, to which reference is now made.

Figure 1 comprises a plan view of one type of core embodying this invention. This particular type core will hereinafter be referred to as the. marginally undercut" core. The dotted lines in Figure l represent a cross-sectional View of a roll of tape wound upon the core.

Figure 2 is a cross-sectional view of .the core of Figure 1, also showing a cross-section of a roll of tape wound upon the core.

Figure 3 is a perspective View of a marginally undercut tape core, upon which is Wound a roll of pressuresensitive adhesive tape.

Figure 4 is a View, partially in plan and partially in cross-section, of a different embodiment of a core of this invention. This particular embodiment will hereinafter be referred to as the bevelled core.

' Figure 5 is a View, again partially in plan and partially in cross-section, of another embodiment which will be referred to as the convex face type core.

lt will, of course, by understood that the constructions of the core particularly shown in the drawing could be modified, yet remain Within the scope of my invention,

and that l do not intend to limit myself except as stated in the claims appended herewith.

Referring now to the drawings in more detail, reference character 2, in all the gures, represents, generally, an annular ring of paper of plastic material, comprising the main body of the core. Although, in the embodiment shown, the core is of solid construction, it could equally well be constructed so as to have a thin, angular shell for its periphery, with an inner framework supporting said shell. Plastic cores of that type construction are shown, for example, in Waldo G. Bretson et al., United States patent application No. 150,296.

in the form of core shown in Figures 1, 2 and 3, the marginal edge portions d and 5 of the core have been cut radially inward so that the core section is considerably less thick at its edge portions than it is at its midportion. This, in effect, provides a peripheral ridge 3 which extends completely about the circumference of the core. When this marginally undercut core is Wound with tape, the initial lap thereof, and succeeding laps in tape roll 6, are supported by this ridge. The edges of the tape do not contact core edges (or shoulders) 4 and 5.

I have found that a roll of ltape is highly resistant to telescoping if it is wound upon a marginally undercut core wherein (as shown in Figures l, 2 and 3) the width of ridge 3 is somewhat more than one-half the overall width of the'core: for example, in a core which is onehalf inch wide, I have found that good results are obtained if ridge 3 is 1%6" wide and each of shoulders 4 and 5 is %2" wide. Ridge 3 is thus 1/8 wider than the total width of the two shoulders 4 and 5. The marginal edge portions of the core illustrated in Figures 1, 2 and 3 may be marginally undercut (i. e., cut radially inward) approximately lA. The dimensions given above are not critical, however, and are given merely for purposes of illustration.

In the core shown in Figure 4 of the drawings, which I refer to as the bevelled core, the peripheral edges of the core are removed, so that again, as in the marginally undercut core heretofore described, tape roll 6, wound upon the core, is supported by the core only at the mid-portion of its width, with no rigid support under the edges of the tape roll. As an illustrative example, edge portions 7 and S may be bevelled radially inward W64", and inward of the width of the core that same distance. Again, these distances are not critical.

I refer to the core of Figure 5 as the convex face core. In that core, the concept of providing a tape core and roll assembly without rigid support under the roll edges is achieved by curving the peripheral surface of the core axially of the core, so that edge portions 9 and 10 thereof will lie farther inward radially of the core than does crest 11 of the cores curving surface, upon which tape roll 6 is supported. In this embodiment of core, I have found that good results are obtained if the diameter of the core through either of its edge portions is approximately 1/6 less than its diameter through its mid-portion.

When rolls of tape wound upon the core of this invention are held under conditions of varying humidity and temperature, the tape assumes a slightly puckered appearance adjacent the edge portions of the core, but the roll shows no tendency to telescope. Under the same conditions, rolls wound on conventional cores having a full outer surface are found to telescope badly.

The present core also permits the use of higher winding tensions without resulting in telescoping, Such higher winding tensions are frequently desirable in order to minimize the inclusion of air pockets and to cause the adhesive coating to completely contact the back surface of the adjacent iilm backing. Furthermore, the

present core, by providing means whereby the compres-l sion between adjacent layers of tape can be re1ieved minimizes the oozing of adhesive from between the edges.

of the tape as a result of squeezing of the tape roll.

The marginally undercut cores of this invention may` be made by removing the marginal edge portions of cardboard cores such as heretofore have been used. Also any of the embodiments of this invention may easily bemade from plastic, for plastic cores are ordinarily formed by extrusion molding, and the novel construction of the present core can be readily accomplished by proper design of the mold.

What I claim is:

1. As a new article of manufacture, an assembly comprising an annular core having a roll of pressure-sensitive adhesive tape wound upon it, said assembly providing a tape roll which is resistant to lateral displacement of said tape on said core by reason of compression of the edge portions of said tape, the width of said core-consisting of a rst marginal edge portion, a second, opposite marginal edge portion and a mid-portion lying between said marginal edge portions, the diameter of said core being greater through said mid-portion than through either marginal edge portion, whereby said adhesive tape, circumvolutely wound upon said core is supported only by said mid-portion of said core, the edge portions of said tape thereby being displaceable radially inward when compression occurs.

2. As a new article of manufacture, an assembly comprising an annular core having a roll of pressure-sensitive adhesive tape wound upon it, said assembly providing a tape roll which is resistant to lateral displacement of said tape on said core by reason of compression of the edge portions of said tape, the peripheral surface of said core being curved axially of the core so that the edge portions of said peripherial surface will be further inward, radially of the core, than the mid-portion thereof, whereby said adhesive tape, circumvolutely wound upon said core is supported only by said mid-portion of said core, the edge portions of said tape thereby being displaceable radially inward when compression occurs.

References Cited in the file of this patent UNITED STATES PATENTS try),

Images