US3179245A - Cores for adhesive tapes - Google Patents

Description

April 20, 1965 F. G. BASTIAN, JR

CORES FOR ADHESIVE TAPES Filed NOV. 5, 1962 ATTORNEY shz.

United States Patent O surname cones non Annasivn TAPES Fred G. Bastian, in, (lair Lawn, llll., assignor to lohns- Manville (Corporation, New York, N.Y., a corporation of New York Filed Nov. 5, H62, Ser. No. 242,030 ltl Claims. (Cl. 2436-59) This invention relates to an improvement in the art of winding tapes into rolls, to the improved rolls of tape and to the novel core construction employed therein. Although not limited to use in connection with such materials, the invention finds particular utility with respect to pressure-sensitive adhesive tapes, e.g., cellophane tape, plastic film tape, etc.

Adhesive tapes including pressure-sensitive adhesive tapes, are usually sold in roll form. A strip of tape is wound upon and supported by a rigid core which most frequently is made from paper such as cardboard or another material such as a synthetic resin. As produced, these tapes are wound about the cardboard or plastic core and a prescribed amount of tension is used in the winding operation to properly secure each turn in place. However, it is a difficult task to gauge and control accurately the winding tension. For instance, variations may occur as between different tapes being wound owing to such factors as uneven adhesive coating thickness across the width of the web, uneven drag or friction at different speeds, an unevenness and tension resulting from slitting tapes of various different widths from the same web.

As a result, certain rolls may be wound with excessive tension. In such rolls the radial compression or squeezing may cause telescoping. By telescoping it is meant the lateral displacement of the turns in the roll towards one side, the amount of the displacement increasing outwardly from the core so that a funnel-like effect is produced. This telescoping may take place gradually and a defective quality may not be apparent prior to packaging.

A further cause of ultimate telescoping rises from variations in atmospheric conditions. Particularly, with respect to hydroscopic tapes, e.g., cellophane. tapes, com pressive forces in the roll result from high atmospheric humidities to which the roll of tape may be subject in certain localities. Moisture is readily absorbed by the cellulose film through its exposed edges and this causes swelling which results in the building up of considerable radial compression or squeezing force. Telescoping results from an attempt to relieve the pressure.

orderto relieve the pressure of the roll. Neither can the pressures be relieved by radial contraction of the tape roll for in most cases, the tape has been wound upon an incompressible core.

Inasmuch as a good portion of the adhesive tape sold commercially is employed in dispensers in one way or another, the telescoping of the tape roll causes crease of the total roll width, the result being that a telescope roll may not be insertable in the dispenser designed for a particular width. Moreover, the development of telescoping after the roll has been inserted results in a binding of the roll against the adjacentlsidewalls so that it will not turn freely. Even if provisions are made for this dispenser design, the transverse displacement of the tape may put it out of desired alignment with other parts of the dispenser through which the tape is drawn.

Lastly, a serious psychological or sales-wise impression may be made upon the user because of the poor appearance of the roll, which is apt to cause the potential buyer an in- 3,179,245 Patented Apr.- 20, 1965 to jump to an unwarranted conclusionthat there is something defective about the tape itself.

Consequently, many attempts have been made to overcome this particular problem. One such attempt has been by the use of a corrugated core. This may be illustrated by US. Patent No. 2,350,369. However, these particular rolls have a serious drawback in that they are rather high in cost and, in some cases, are diflicult to make for the small diameter size cores.

A second attempt at overcoming this problem may be illustrated by US. Letters Patent No. 2,772,774. By

that invention, the core was so designed that when the.

tape was wound upon it, there was a space between the edges of the inner most wrap of tape and the marginal edge portions of the core. Thus there was no rigid core support underlying the edges of the tape roll. The theory behind the core structure was that when radial compressive forces are created in the edge portion of the tape roll, the tape of the roll could be displaced inwardly towards the axis of the core to relieve the tensions in the roll. However, this particular concept has likewise been met with several disadvantages. Not only was it necessary to design and produce a specific core, but the necessity of achieving proper alignment upon an uneven surface when wrapping or winding the tape upon the core required very accurate control of the winding process.

It has now been discovered that the above disadvantages of telescoping may be overcome by providing a new type of core structure. Specifically, a core is initially provided with a cellularor sponge-like plastic outer layer. After the tape is wound about the novel core, the roll of tape is subjected to heat to such a point as to collapse the cell structure of the sponge-like layer. Proper selection of the softening point of the cell structure and of the degradation points of the tape and core are so controlled that collapse of the cell structure may be obtained without deleteriously affecting theother portions of the roll structure.

Objects It was therefore an object of this invention to provide a tape core which would permit the pressures built up within a roll of tape during the winding operation thereof to be relieved subsequent to the winding up operation so as to overcome and avoid the phenomenon of telescoping.

An'additional object of this invention was a provision of a core structure which may be used in packaging pressure-sensitive adhesive tapes whereby the effects of excessive compression or squeezing forces. set up during winding of the tape may be subsequently relieved.

Additional objects and further scope of applicabilityof thepresent invention will become apparent from the 'detailed description given hereinafter, the preferred em bodiment of which has been illustrated infthe accom: panying drawing by way of example only wherein;

FIGURE 1 is a perspective view of a tapeco're of this invention upon which is wound a roll of adhesive tape illustrating the core foam and PEGURE 2 is another perspective view of the same roll Specifically, and with continuing reference to the ac-v companying drawing wherein like reference numerals designate similar parts throughout, this invention consists of a roll of adhesive tape 1d, wherein the hollow tube or core structure 12 which serves as a support for the roll support prior to its. collapse;-

of tape 16 is provided with an outercoating of rigid or semi-rigid synthetic resinous sponge or cell-like material 14. The tape is thereafter wound upon the core structure in a conventional manner. As illustrated in FIG. 2, subsequent'to the winding operation, the rolled goods are heated to a temperature sufficient to collapse the sponge structure and form the new interlayer 18 and thereby relieve the pressure created in the winding tension. The composition of the sponge structure is so selected as to have a collapse point less than that temperature which would deleteriously affect the core and/ or the adhesive tape composition.

General description of the invention A more complete. understanding of the invention may be obtained by reference to the following example of operation within the scope of this invention. In this example the parts and percentages are by weight unless otherwise indicated. 7

Example A 40-inch wide hollow tube-like structure was constructedof a laminated paper so as to have a wall thickness of about 0.125. A 0.125 inch layer of a semi-rigid polystyrene foam was then laminated to the exterior surface of the core. A pressure-sensitive adhesive coated vinyl film was wound upon the plastic sponge coated paper tube using conventional winding techniques. Upon being completely wound, the tape was suspended on a support bar and the tape and core heated to 105 C. At that temperature the plastic sponge softened and collapsed relieving the pressure created by the winding tension. The full Width of tape was allowed to cool to room temperature and then cut into individual rolls. No telescoping was subsequently observed.

. The tube'base may be of any conventional structure such as laminated paper of the example, or thermoplastic or thermosetting resin but is to have a softening point above about 150 C. This permits a plastic sponge covering and tape wound about it to be beneficially exposed to temperatures up to about 135 C. without the possibility of collapsing or softening of the tube itself.

The layer of the rigid or semi-rigid plastic foam may vary in thickness fromabout 0.01 to about 0.5 inch. The foam shall have a compression deflection value ranging from 0.5 to 100 psi. for a deflection at 20 C. and is preferably produced from material having softening points ranging from C. to 135 C. The purpose of this range is to avoid premature collapse of the plastic sponge during the winding operation and to avoid exposing the wound tape to potentially destructive high temperatures during the controlled collapse of the sponge portion of the core. The compression deflection characteristics of the sponge portion are dictated by the tape winding tensions required. That is, tapes wound at low tension may require the sponge to have a low compression deflection value, whereas tapes wound in the high,

tensions will necessarily require the sponge to have a higher compression deflection value. The collapsible synthetic resinous foam may be manufactured from base materials such as, polystyrene, polyvinyl chloridefpolyvinylacetate, copolymers of polyvinyl chloride and poly- Viny acetate, and polyurethane.

The choice of the ingredients for the tape itself may be varied within the skill of the art. Representative pressure-sensitive adhesives are well-known in the art ,and may be illustrated by US. Letters Patents Nos.

2,236,527, 2,410,078, 2,438,195, 2,601,016 and others. Generally these adhesives have a rubbery base of natural or synthetic rubber which provides cohesion elasticity and retraction, modified with a tackifier such as a rosin or ester gum which serves to increase adhesion and stretchiness.

It is believed the above provides a complete description of the invention in such manner as to distinguish it from other inventions and from what is old, and provides a description of the best mode contemplated of carrying out the invention and thereby complies with the patent statutes.

It is to be understood that variations and modifications of the invention, as illustrated by specific examples herein, may be made Without departing from the spirit of the invention. It is also to be understood that the scope of the invention is not to be interpreted as limited to the specific embodiments disclosed herein but only in accordance with the appended claims, when read in the light of the foregoing description.

What I claim is:

' 1. An article of manufacture comprising a roll of tape wound under tension upon a permanent cylindrical core, so as to be subject to the compressive forces of the winding to cause telescoping of the tape, comprising a generally cylindrical core assembly having a relatively rigid structure of predetermined and fixed dimensions, a length of tape convolutely wound about said core assembly under tension, and an intermediate layer between said core and said tape comprising a collapsible synthetic resinous foam, having a collapse point between 35 and 135 C. and less than the softening point of said tape and core, whereby when the roll of tape has been heated to said collapse point the foam collapses and relieves the tension and compressive forces acquired during winding.

2. An article as described in claim 1' wherein the foam is polystyrene.

3. An article as described in claim 1 wherein the foam is polyurethane.

4. A method of providing a relatively telescope-free roll of tape, comprising providing a rigid base core, modifying said core by affixing to the outer surface thereof a collapsible synthetic resinous foam having a collapse point between 35 and 135 C., whereby, when heated, said foam collapses, winding a film of tape on said modified core under tension, and heating said core so as to collapse said foam to thereby relieve the winding tension therein. Y

5. A method as described in claim 4 wherein the tape is a pressure-sensitive adhesive tape.

6. A method as described in claim 4 wherein the foam is polystyrene.

7. A method as described in claim 4 wherein the foam is polyurethane.

8. An article of manufacture comprising a roll of tape 7 sive forces acquired during winding of the tape, thereby providing a relatively telescope-free roll of tape.

9. An article as described in claim 8 wherein the foam is polystyrene.

10. An article as described inclaim 8 wherein the foam is polyurethane.

References Cited by the Examiner UNITED STATES PATENTS 2,006,333 7/35 Angell et a1.

2,350,369 6/44 Sampair et al 206-59 2,394,639 2/46 Seen 242-1182 2,659,543 11/53 Guyer 242-68.5 2,982,493 5/61 Sibille 242ll8.2

THERON E. CONDON, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,179, 245 "April 2 0, 1965 Fred G. Bastian, Jr.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, 1ine 24, after "0.125", first occurrence, insert inch line 70, after "cohesion" insert a comma.

Signed and sealed this 16th day of November 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. AN ARTICLE OF MANUFACTURE COMPRISING A ROLL OF TAPE WOUND UNDER TENSION UPON A PERMAMENT CYLINDRICAL CORE, SO AS TO BE SUBJECT TO THE COMPRESSIVE FORCES OF THE WINDING TO CAUSE TELESCOPING OF THE TAPE, COMPRISING A GENERALLY CYLINDRICAL CORE ASSEMBLY HAVING A RELATIVELY RIGID STRUCTURE OF PREDETERMINED AND FIXED DIMENSIONS, A LENGTH OF TAPE CONVOLUTELY WOUND ABOUT SAID CORE ASSEMBLY UNDER TENSION, AND AN INTERMEDIATE LAYER BETWEEN SAID CORE AND SAID TAPE COMPRISING A COLLAPSIBLE SYNTHETIC RESINOUS FOAM, HAVING A COLLAPSE POINT BETWEEN 35* AND 135*C. AND LESS THAN THE SOFTENING POINT OF SAID TAPE

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