US3066794A - Tape core - Google Patents

Description

Dec. 4, 1962 J. D. MULi-u-:RENl ETAL TAPE CORE Filed June 50, 1961 lO 3 l I l l I I3 l l l FIG! INVENTORS JOSEPH D. MULH EREN JOSEPH C. GUlNAN Y Mf ATTORNEY 3,056,794 TAPE EUR@ Joseph D. Miribel-en, Waterviiet, and Joseph C. Guinan, Troy, N.Y., assignors to Norton Company, Troy, NX., a corporation of Massachusetts Filed .lune 30, 196i, Ser. No. 121,147 2 Claims. (Cl. 2do- 59) The present invention relates generally to tapes in roll form and more particularly to pressure sensitive adhesive tapes in roll form and to cores for supporting such tapes in such form.

The problem of telescoping or the displacement of the convolutions of a tape roll laterally from one side of the core upon which it is wound is one which has been particularly bothersome to the pressure sensitive tape manufacturers.

Several solutions have been suggested including that of U.S. Patent No. 2,772,774 to George R. Rabuse wherein a core is provided which supports the tape solely at the central portion of its width, leaving the lateral edges unsupported. The present invention constitutes an improvement over cores of the type described in the Rabuse patent.

It is an object of the present invention to provide an improved core for use in supporting pressure sensitive adhesive tapes wound thereon in rolly form.

Another object of the invention is to provide an improved roll of tape which is resistant to telescoping Additional objects, if not specifically set forth herein will be readily apparent to one skilled in the art from the following detailed description of the invention:

In the drawings:

FIGURE 1 is a plan view of one type of core embodying the present invention.

FIGURE 2 is a cross-sectional view of the core of FIGURE l showing a cross-section (in dotted lines) of a roll of pressure sensitive tape Wound upon the core.

FIGURE 3 is a plan View of a different embodiment of a core of the present invention.

FIGURE 4 is a cross-sectional view of the core of FIG- URE 3 showing a cross-section (in dotted lines) of a roll of pressure sensitive' tape wound upon the core.

Generally, the present invention is based on the discovery that it is desirable to wind pressure sensitive tapes upon cores under substantial tension in order to produce hard rolls. This minimizes undesirable gapping and iiuting of the rolls upon aging. However, hard winding promotes the tendency to telescope Many variations of core construction have been tried to permit hard winding without telescoping. The structure of the Rabuse cores illustrated in U.S. Patent No. 2,772,774 appear to be the closest prior art to the solution arrived at by the present inventors-but with one major and important difference. It has been found that supporting the tape by the mid-portion only of a core as taught by Rabuse does not permit sufficiently hard winding of the tape--there being a tendency for the tape to slip to one side or the other during winding. The cores of the present invention support the tape across the entire width thereof and achieve relief from telescoping not by providing relief areas for the compressive forces Within the roll but by providing a positive locking of the tape to the core whereby the compressive forces are balanced and telescoping is minimized.

Specifically, the present invention relates to cores for pressure sensitive adhesive tapes wherein the tape-supporting peripheral surface of the core is provided with a plurality of areas of different elevation-all of which are in contact with the tape wound thereon. The change in elevation of the areas provides a positive lock against displacement of the tape and is carried through the su- Bfihjti Patented Dee. 4, i955@ perposed convolutions of tape, providing a slight curvature of the tape roll in cross-section. This slight curvature has been found sutiicient to prevent compressive forces built up within the roll from causing the convolutions to displace laterally in the undesirable telescoping action.

Referring now to the drawings, the core illustrated in FIGURES 1 and 2 provides a dat central portion 11 of the peripheral surface 12 of core 18, and a pair of surfaces f3 of different elevation than surface 11. Surfaces 13 are tapered downwardly from the central portion il of core 10 at a very slight angle-preferably 1/2". As will be seen from FIGURE 2, when a tape strip has been wound convolutely on core 10 to form a tape roll i4 (shown in cross-section by the dotted lines), the tape is in intimate contact with the entire peripheral surface I2 of core itipressing against both surface 11 and surfaces f. This produces a curvature in the tape which is repeated out to the periphery of the roll as shown at 15. A tape roll on such core will be very resistant to telescoping and, since the tape is in hrm contact with the entire width of the core, can be wound very hard without difficulty in keeping true alignment of the 4edges of the roll.

The core of FIGURES 3 and 4 is `a further variation of the present invention. The peripheral surface 22 of core 2G is composed of alternately disposed wedge shaped surfaces 2l raised above the normal surface 22 of the peripheral surface of core 2t). The elevation of surfaces 21 is critical only in that it must not be great enough to permit the tape wound thereon to bridge the normal surfaces 22 of core 20. A distance of 0.0015" has been found desirable in practice. In the preferred embodiment of this type of core, the wedge-shaped surfaces have an included angle of 41. The: tape wound upon such core will reproduce the pattern throughout the convolutions as shown at 24 of FIGURE 4. This locks the tape in roll form positively on the core and minimizes telescoping The present invention is not limited to any particular type of pressure sensitive tape but includes both paper and film-backed tapes. The cores of the present invention are preferably made from a suitable plastic but may be of pressed paper or the like if desired. Obviously many variations and modifications may be made without departing from the spirit and scope hereof and hence only such limitations are intended as are imposed in the appended claims.

We claim:

l. A roll of pressure sensitive tape comprising: an annular supporting core having a tape-supporting surface, said surface having a taper from the mid-portion thereof towards each edge, said taper being towards the axis of said core; and a plurality of convolutions of pressure sensitive tape wound under tension about said surface, said first convolution of tape being of substantially the same width as the surface of said core and entirely in contact with said surface of said core and conforming to the taper thereof, and the remaining convolutions of tape being superposed over and conforming to said iirst convolution whereby the outer surface of each convolution has a slight convex curvature and telescopng of the roll is prevented.

2. A roll as in claim l wherein said surface comprises a hat central section and tapered areas on each side of said flat section, the degree of taper not exceeding 1/2.

References Cited in the le of this patent UNITED STATES PATENTS 1,769,928 Lindenberg July 8, 1930 1,948,438 Brunet Feb. 20, 1934 2,772,774 Rabuse Dec. 4, 1956

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