US 3113713 A
Description (OCR text may contain errors)
Dec. 10, 1963 F. w. GREEN GLUE LAP CLOSURE 2 Sheets-Sheet 1 Filed Sept. 29, 1961 INVENTOR. FRANK h- Giff/V 3,113,713 GLUE LAP CLOSURE Frank W. Green, East Longmeadow, Mass, assignor to West Virginia Pulp and Paper Company, New York, N .Y.,. a corporation of Delaware Filed Sept. 29, 1961, Sier. No. 141,828 6 Claims. (Cl. 229-51) This invention relates to a new and improved glue lap closure for paperboard cartons, boxes and other containers. More specifically it relates to a glue lap closure with a specially shaped pattern of adhesive areas in the lapped portion providing a tight seal for the container yet which can be easily and cleanly opened without the use of a knife or other tool of any kind.
At the outset it should be pointed out that the word glue is used herein in the generic sense as it is often employed in the folding box and corrugated box industries to denote any kind of suitable adhesive substance and is not used in the strict sense of the word which is limited .to adhesives of animal origin.
In the past many types of glue lap closures have been used. Some of these closures are completely glued along the full length and width of the lapped portions. Opening these containers at the glue lap by hand is quite difficult, if not impossible. Other glue lap closures have glue applied in patterns of dots, or lines, or are printed with various patterns of glue-rejecting ink at the glue lap which prevent or resist adherence at those areas, to provide a weakened and more easily openable closure.
In accordance with this invention, the glue is applied to the lapped portion in a special pattern of decreasing bonding area in the direction of pull, thus allowing the ease of opening to be increased and the opening speed to be accelerated as pull is exerted. A further and most important advantage of the invention is the elimination of delaminated areas which in other forms of glue lap closures may be formed in areas of the paperboard adjacent to the glue lap as a result of failure of the closures to provide for a clean release when pulled open.
The invention is further described in the following drawings, in which FIG. 1 is a plan view of a paperboard carton blank showing the overlapping and underlapping portions of the glue lap closure before the carton is formed and closed, the underlapping portion having a preferred form of glue pattern applied thereon;
FIG. 2 is a perspective view showing a paperboard carton made from the blank of FIG. 1 before the over lapping and underlapping portions of the glue lap closure are sealed together;
FIG. 3 is an enlarged fragmentary view of the gluerejecting ink pattern and glue line on the underlapping portion of the glue lap closure of FIGS. 1 and 2;
FIG. 4 is an enlarged fragmentary view of another embodiment of the underlapping portion of the glue lap closure showing the same ink pattern but with the glue line adjusted to give stronger adhesion;
' FIG. 5 is another enlarged fragmentary view of the underlapping portion of another embodiment of glue lap closure showing a glue line applied over a somewhat different ink pattern;
FIG. 6 is a perspective view showing thecarton of FIG. 2 after sealing;
FIG. 7 is a perspective view of a paperboard carton with an opened glue lap closure which was sealed with glue in the form of conventional rectangular patterns, illustrating the delamination which can occur when the special glue pattern of this invention is not utilized.
In FIG. 1, the paperboard carton blank is scored to provide bottom panel 10, side panels 12 and 14 with side end flaps 16, '18-, 20 and 22, respectively, and end panels 24 and 25, all of which form the bottomhalf of the carton when the side end flaps and side end panels of each end are secured together.
The blank is also scored to form top panel 28, hinged to side panel 14, top end flaps 3t 32 and front flap 34, all of which constitute the top half of the carton. The top half of the carton is closed and sealed by gluing the top end flaps 30 and 32 to the side end flaps 24 and 26, respectively, and securing part of front flap 34 to the upper portion of side panel 12. Front flap 34 includes pull tab 36 at the end thereof foldably connected to the body portion of the front flap. This body portion of the front flap becomes overlapping portion 38 of the glue lap closure when the carton is sealed. Pull tab 36 and overlapping portion 38 each overlap a portion of side wall 12 when the carton is sealed,.the portion of side wall 12 which is covered by overlapping portion 38 being desig-- nated as underlapping portion 40' of the glue lap closure.
Overlapping portion 38 is scored with curvilinear perforated lines 42 and 44, and top panel 28 has perforated lines 46 and 48 connecting with the curvilinear perforated lines 42 and 44 at points 50 and 52 so as to provide a convenient rip opening means of gaining access into the carton from the top of the carton. Underlapping portion 40 has a printed pattern 54- of glue-rejecting ink, with triangular areas 56 remaining unprinted. Glue line 58,
is applied across the length of the underlapping portion 4% including printed portions 54 and portions of the unprinted triangles 56. The apices of the unprinted triangles 56 preferably extend to the upper edge 60 of underlapping portion 40, as shown in FIGS. 1-4, giving a somewhat neater appearance to this area of the closure after it has been opened because none of the printed area is as subject to delamination effects. Other embodiments of the positions of the triangles are also contemplated by this invention as in FIG. 5, where the triangles appear below the edge 60. Sometimes when glue lap closures of this embodiment (FIG. 5) are carelessly opened some very slight delamination may occur extending from the apices of the triangles of the unprinted areas into the printed areas above resulting in a somewhat unsightly appearance.
Any type of suitable ink may be used in the printed area 54 as long as it rejects or interferes with the adhesion of the glue applied to the inked surface.
by Southern Adhesives Corporation, Richmond, Virginia,
performs very. well as a bonding agent for glue lap clo sure for cartons made of kraft linerboard and that the bonding power of such glue is substantially rejected by the chlorinated rubber base specified above. The amount of glue in the unprinted triangular areas 55 may be adjusted as desired for greater or less adhesion depending upon the total area within the triangular area covered by glue. FIG. 4 shows the glue line 58 moved down below the apices of triangular areas 56 giving a greater glued area for the same width of glue line and thus a stronger glue lap when the carton is sealed.
It has been a conventional practice in the past to print the overlapping or under lapping portions of glue lap closures with glue-rejecting ink leaving unprinted areas of various shapes, such as rectangles. and then apply a glue P 3,113,713 Ice Patented Dec; 10, 1963' An example ofsuch an 1nk 1s a chlorinated rubber base rotagravure ink 3 iine across the unprinted area'to provide areas'of adhesion. When cartons with these glue lap closures are opened, areas adjacent to the bonded areas in the direction of the pulling force are pulled apart or delarninated. As shown in FIG. 7, where the unprinted areas are in the forms of rectangles, strips of delaminated material 64 the width of the rectangular unprinted areas 62 can be formed because the adhesive power of the glue at the upper edge of rectangular area 62 is stronger than the internal bonding strength of the overlapping portion of the paperboard at such points. The delarnination continues as the top is opened producing an unsightly and incompletely opened box.
The instant invention arose from the discovery that by providing the adhesive areas in the shape of triangles with the apices of the triangles in the direction of pull, the above serious delarnination consequences are eliminated because the areas of delamination at the glued triangular areas converges and breaks away cleanly and neatly at the apices, or close thereto, allowing the carton to be easily, neatly and cleanly opened. In the other embodiments as shown in FIGS. 4 and 5 where the glue bonds are in the form of tapered areas which do not terminate in a point, the decrease in width of their converg ing areas still produces a substantial decrease in the tendency to cause delamination.
It is sometimes necessary, when an increase in the strength of the glue lap closure is desired for packaging a heavier item in the carton, to move the glue line below the apices of the unprinted triangles as shown in FIGS. 4 and 5, thus giving more glued area for the same width glue line.
The ink pattern can also be changed to provide unprinted triangular or tapered areas with broader bases so as to permit a stronger bond where the glue lap closure begins. It is, of course, essential to this invention that the bonding areas be larger nearer the pull tab and progressively decrease as they extend away from the pull tab.
The use of a glue-rejecting ink pattern between and within the glue lap closure of this invention is merely an expedient which permits obtaining triangular or tapered bonding areas in the glue lap closure by the simple and convenient procedure of applying a glue line across the printed and unprinted area with a glue applying Wheel. It is readily apparent of course that a printed glue-rejecting ink pattern can be done away with if the glue is applied initially in the form of triangles or taperedv areas within the glue lap closure area.
It is also easily seen that the triangular or tapered glue bond areas, and the glue-rejecting ink patterns it utilized, can be applied to either or both of the overlapping and underlapping portions of the glue lap closure.
While various embodiments of this invention have been described above, the invention should not be limited to the exact details as described but only by the scope of the claims set forth below.
I claim as my invention:
1. A glue lap closure for a paperboard carton which can be easily opened Without any substantial delamination comprising:
an overlapping portion and an underlapping portion of the paperboard carton, a pull tab foldably connected to the end of the said overlapping portion, 7
a glue bond within and between the overlapping portion and underlapping portion and adhesively securing together said portions,
said glue bond being in the form of a series of tapered areas pointing away from the said pull tab, and
each of said tapered areas having a bottom edge nearest the pull tab with the bottom edge of each tapered area being in substantial alignment and with each bottom edge being the widest line through said tapered areas measured parallel to said bottom edge.
2. A glue lap closure for a paperboard carton which can be easily opened without any substantial delamination comprising an overlapping portion and an underlapping portion of the paperboard carton,
a pull tab foldably connected to the end of said overlapping portion,
a pattern of glue-rejecting ink printed within and between the overlapping portion and underlapping portion leaving a series of unprinted tapered areas pointing away from the pull tab,
a glue line within and between the overlapping portion and underlapping portion extending across the said printed pattern and the said unprinted tapered areas, whereby the said portions are adhesively secured together by a series of v glue bonds in the form of tapered areas pointing away from the pull tab, and
each of said glue bonds in the form of tapered areas having a bottom edge nearest the pull tab with the bottom edge of each glue bond being in substantial alignment and with each bottom edge being the widest line through said glue bond measured parallel to said bottom edge.
3. The glue lap closure of claim 2 in which the said' unprinted tapered areas are in the form of unprinted triangles with their apices pointing away from the pull tab.
4. The glue lap closure of claim 3 in which the said glue line extends, across a substantial portion of said unprinted triangles including their apices.
5. The glue lap closure of claim 4 wherein the apices of the said unprinted triangles extend to the edge of the overlapped portions opposite from the pull tab.
6. In a paperboard carton having a top hinged to the back of the carton, top side flaps secured to opposite sides of the carton, a glue lap closure securing the top to the front of the carton, and perforated lines in the top and in a portion of the glue lap closure providing a top rip open-.
ing means, and improvement in the glue lap closure to provide easy opening of the carton by hand without incurring any substantial delarnination of areas adjacent to the glue lap closure, comprising 7 a top front flap foldably connected to the front of the top and divided by a score line into an overlapping portion and a pull tab at the end thereof, an underlapping portion of the front wall of the carton over which lies the overlapping portion of the said top front flap,
a pattern of glue-rejecting ink printed on the surface of said underlapping portion which is overlain by said overlapping portion, said pattern leaving a series of unprinted equilateral triangular areas having their apices pointed away from the pull tab,
a glue line on said surface of said underlapping portion extending across the said printed pattern and the said unprinted equilateral triangles, whereby the said overlapping and underlapping portions of the carton are adhesively secured together by a series of glue bonds in the form of equilateral triangles and with their apices pointing away from the pull tab, and
each of said glue bonds in the form of an equilateral triangle having its bottom edge nearest the pull tab with the bottom edge of each glue bond being in substantial alignment and with each bottom edge being the Widest line through said glue bond measured parallel to said bottom edge.
References Cited in the tile of this patent UNITED STATES PATENTS 2,113,927 Alfred Apr. 12, 1938 2,122,480 Lowey July 5, 1938 2,133,946 Bloomer Oct. 25, 1938 2,810,507 Saunders Oct. 22, 1957