US 3810813 A
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May 14, 1974 G. ELLIS CLOSURE-FORMING STRIP WITH AN ATTACHED TEAR STRIP STRUCTURE Filed July 20, 1972 United States Patent Office US. Cl. 161-145 1 Claim ABSTRACT OF THE DISCLOSURE The invention resides in a tear strip structure wherein a conventional closure-forming strip gummed on one side has a tear tape adhesively bonded to the gummed side of the strip. The tear tape occupies a minor medial longitudinal section of the strip and is not adhesive at room temperature or when moistened.
Gummed tape is widely used in effecting closure of various types of packages, such as paperboard and corrugated paperboard cartons and the like. Conventional tapes of this nature are usually formed of kraft paper having one side coated with a water-sensitive or a pressure sensitive adhesive.
In opening such packaged cartons, it is necessary to slit or tear the tape along the joint between the closure flaps of the carton so that the flaps can be engaged at the joint and swung open. Usually, a knife or like cutting instrument is used to slit the tape.
The present invention seeks to provide a tape slitting means incorporated in the structure of conventional gummed strips whereby such strip may be readily severed or slit along its medial longitudinal section.
The invention comprises an elongated strip which may be of paper having a water-sensitive, pressure sensitive or heat sensitive adhesive coating on one side, and a tear tape both side surfaces of which are non-adhesive when moistened or subjected to temperatures of the order of room temperature adhesively bonded to the adhesive coated surface of the strip. The tear tape is located substantially midway between the side edges of the strip and has a width of minor degree with respect to the strip. Thus, there is a minor normally non-adhesive medial section in the longitudinal direction of the completed structure bounded on each side by a marginal Water-sensitive adhesive section.
The invention will be described with reference to the accompanying drawing, in which FIG. 1 is a plan view of a tape structure in accordance with the invention,
FIG. 2 is a section on line 2-2 of FIG. 1,
FIG. 3 is a cross-section of a tape suitable for use in the structure, and
FIG. 4 is a diagrammatic elevation of a machine for forming the structure of the invention.
Referring to FIGS. 1 and 2, is a gummed strip, which may be of conventional form such as a kraft paper strip 11 having a layer 12 of water-sensitive adhesive on one side thereof. It will be understood that this adhesive layer is stable at room temperature and requires to be moistened to render it adhesive.
It is also understood that with slight modifications a pressure-sensitive or a heat-sensitive adhesive could be used in place of the water-sensitive adhesive.
3,810,813 Patented May 14, 1974 Superimposed on and adhesively bonded to the adhesive layer 12 is a tear tape 13. While the tape 13 may be of any suitable construction, it is preferably of greater tensile strength than that of the strip 10. It is positioned on the mid longitudinal section of the strip and extends substantially from end to end thereof. Its width is but a minor portion of the overall width of the strip. In the modification shown, it is about one-third of the overall width. Moreover, it has a thickness which is preferably substantially less than that of the strip.
A suitable tear tape has been found to be that disclosed in FIG. 3. This tape, as shown, comprises two layers 14 and 15. Layer 14 comprises a plurality of elongated fibrous threads or strands or filaments 16, which may be of cotton, rayon, polyester, polyamide, or other synthetic man made or natural fibers, films, or strands. They are embedded in a synthetic resin material 17, such as polymerized vinyl chloride, cellulose acetate, methyl methacrylate, polystyrene, hot-melt adhesive compositions, and the like.
Layer 15 consists of a hot-melt adhesive, which may be of the same or different composition as that of material 17, bonded adhesively to layer 14. Layers 14 and 15 are both stable at ambient temperatures; that is, neither is of tacky or adhesive nature at such temperatures but, in some cases, layer 15 may be of a composition that becomes tacky and adhesive at a higher temperature at which layer 14 remains thermally stable. More specifically, layer 15 may be heated to a temperature exceeding about 60 C. to render it tacky and adhesive but within a range of, say, about 60 C.- C., in which latter range layer 14 may be thermally stable.
It will be apparent, therefore, that if heat is applied to layer 14 in sufiicient degree to soften layer 15, the tape may then be applied to the gummed side of strip 10 with softened layer 15 in engagement therewith. On subsequent cooling, the tape becomes firmly bonded to the strip.
In order to make the tear tape conveniently available for use in the finished article, it is proposed to sever any desired length in such manner that a pull tab 18 consisting of an end portion of the tape and underlying strip is formed. A cutter of the profile indicated may be employed although other suitable profiles may be employed. Thus, the other end portion of succeeding lengths of strip structure will have a complementary notch 27 formed therein, which will not affect the efiectiveness of the structure to any noticeable degree.
In use, a suitable length of tape structure, as shown in FIG. 1, is employed to unite the closure flaps of a carton or the like. Since the tape 13 is readily visible and may have substantial width, it is easy to apply in such manner that the tape bridges the joint between the closure flaps in the closed position thereof. Since the exposed surface of tape 13 is not adhesively joined to the carton, the tab 18 may be conveniently grasped when the carton is to be opened and the length of tape 13 pulled from the carton, thus freeing the closure flaps for swinging into open position.
Referring to FIG. 4, a suitable arrangement is shown for producing the structure of the invention. A supply roll 19 of gummed strip 10 is provided for dispensing a portion thereof as indicated at 20. A supply roll 21 of tape 13 is provided for dispersing a portion thereof indicated at 22. Portion 22 is led over a guide roll 23 into engagement with the periphery of a heated roll 24, the layer 14 of the tape being in contact with the roll. The now pressure sensitive side 15 of the tape is immediately applied to the gummed surface of the strip portion 20 under the influence of a pressure roll 25. Desired lengths of tape are severed by means of a cutting device 26.
"It will be understood that a supply of the assembled strip 10 and tape 13 may be produced by simply omitting the cutter 26 which may later be employed to form desired lengths thereof.
1. Tear strip structure comprising an elongated strip having an adhesive coating on one side thereof, and a tear tape adhesively bonded to one side of said elongated strip, longitudinally thereof and substantially midway between the side edges thereof, said tear tape consisting of a body of hot-melt adhesive composition having a plurality of UNITED STATES PATENTS 2,307,406 1/1943 Howard 161-145 X 2,895,865 7/ 1959 Humphner 229-51 AS X 3,504,844 4/1970 Stark et a1. 206-59 C X 3,396,900 8/1968 Lucas 229-51 AS PHILIP DIER, Primary Examiner US. Cl. X.R.