WO1992000192A1

WO1992000192A1 - Tear tape

Info

Publication number: WO1992000192A1
Application number: PCT/US1991/004431
Authority: WO
Inventors: Paul R. Mitchell
Original assignee: Mitchell Paul R
Priority date: 1990-06-22
Filing date: 1991-06-21
Publication date: 1992-01-09
Also published as: AU8106191A

Abstract

This invention relates to tear tapes for convenient and simple opening of packages, such as consumer item package wrappers. Known methods of fixing tear tapes to package overwrap material require the use of an organic solvent, molten wax, a hot wheel or shoe, or a pressure sensitive adhesive. The hot shoe method wrinkles the package while tear tape packages made from pressure sensitive adhesives are costly, difficult to manufacture, handle, and store. The present method of making a packaging material (24) includes steps of providing a tear tape (20) having a fusible surface, contacting the fusible tear tape surface with a surface of a wrapping material (22), and directing radiant energy (16) toward a portion of the fusible surface. Also, apparatus (10) for carrying out the method, and packaging material (24) made by the method are disclosed.

Description

TEAR TAPE

Background of the Invention

This invention relates to tear tapes for opening packages.

Package wrappers- particularly for consumer items, are commonly provided with a "tear tape" for simple and convenient opening of the package.

A length of tear tape is arranged to underlie a portion of the wrapper, typically an overwrap, and typically with a free end of the tear tape and overwrap left exposed in the completed package. In one common form, the tear tape is affixed to the overlying wrapper- so that when the free end of the tear tape is grasped and pulled away from the package, the overwrap is torn and the package is opened. To be effective, a tear tape must be adequately affixed to the overwrap. To be most acceptable, a tear tape should be inexpensive and easy to manufacture, and should produce a neat appearance in the final package.

A variety of methods are known for affixing the tear tape to the overlying overwrap. An early tear tape, introduced in the 1950's for use with a cellophane overwrap on consumer packages containing, for example, candy or cigarettes, was a narrow ribbon of cellophane. The tape was treated with a solvent such as methyl cellosolve to make the surface of the tape tacky, and then the tacky surface was contacted with the cellophane overwrap to allow the tear tape to adhere to the overwrap.

Beginning in the 1960's, polypropylene came into use as a tear tape material. Typically a thin layer of microcrystalline wax is used to adhere the polypropylene tear tape to the overwrap. In one method of manufacture that is in current use, a narrow wheel running in molten wax is used to apply a coating of the wax to the tape, or the overwrap, and then the tape is contacted with the overwrap and the wax is permitted to set. In the 1970's, polyester tear tapes were used with polyester overwraps. The tear tape and the overwrap were brought together and then fused by contact with a hot wheel or shoe. This process did not gain wide acceptance because the shoe or wheel caused a crinkle upon contact with the material, leaving a wrinkle in the package and giving the package a poor appearance.

Other tear tapes are coated with a pressure sensitive adhesive during manufacture, but pressure sensitive tear tapes are costly and difficult to manufacture. They are also difficult to handle and store, owing to a variety of technical problems, including blocking and offset.

Suamary of the Invention In general, in one aspect, the invention features a method for making a packaging material, including steps of providing a tear tape having a fusible surface, contacting the fusible tear tape surface with a surface of a wrapping material, and directing radiant energy toward a portion of the fusible surface. In general, in another aspect, the invention features a packaging material made by a method including steps of providing a tear tape having a fusible surface, contacting the fusible tear tape surface with a surface of a wrapping material, and directing radiant energy toward a portion of the fusible surface.

In general, in another aspect, the invention features apparatus for making a tear tape packaging material, including a source of radiant energy, means for contacting a surface of a wrapping material with a fusible surface of a tear tape, and means for directing radiant energy from the source toward the fusible tear tape surface.

In preferred embodiments the tear tape comprises a tear tape ribbon and a coating of a fusible material; the tear tape ribbon is polypropylene; one surface of the ribbon has the fusible coating; the fusible coating includes ethylene vinyl acetate; the tear tape is formed by coextrusion; the wrapping material includes a polymer film, preferably polypropylene; the fusible tear tape surface and the wrapping material surface are brought into contact by passing the wrapping material and the tear tape together over a rotating drum; the radiant energy is provided by an incandescent light; and the radiant energy is directed toward a portion of the fusible surface by means of a lens or a system of lenses.

The method of the invention provides inexpensive packaging material having tear tape affixed to wrapping material in one continuous processing step. The finished packaging material presents a neat appearance and is easy to handle both during its manufacture and in subsequent manipulations.

Description of Preferred Embodiments Drawings

Fig. 1 is a diagram in elevational view of apparatus for making tear tape packaging material according to the invention, showing tear tape, wrapping material, and packaging material in the process.

Fig. 2 is a diagram, of the apparatus of Fig. 1, in sectional view at A-A. Fig. 3 is a diagram, enlarged and in sectional view at B-B, of part of the apparatus of Figs. 1 and 2.

Fig. 4 is a diagram as in Fig. 3, showing alternative tear tape in the process.

Fig. 5 is a diagram, enlarged and viewed in the direction indicated by arrows A, of part of the apparatus in Figs. 1 and 2. Structure

Referring to Figs. 1 and 2, tear tape packaging material making apparatus includes rotating contact drum 10, upon which the tear tape 20 and the wrapping material 22 are brought into contact, radiant energy source 12, and lens means 14 for directing a focussed spot of energy, indicated generally at 16, toward the tear tape and the wrapping material in an area where they are in contact on drum 10.

Tear tape 20 is continuously supplied to contact drum 10 from a roll on tear tape supply spool 21, and wrapping material 22 is continuously supplied to contact drum 10 from a roll on wrapping material supply spool 23. Finished tear tape packaging material 24 can then be used to wrap a package or can be taken up and stored on takeup spool 25. Referring now to Fig. 3, tear tape 20 passes from a tear tape supply (not shown) onto revolving contact drum 10, with a fusible surface 30 of tear tape 20 facing away from drum 10. Wrapping material 22 passes from a wrapping material supply (not shown) onto contact drum 10, and overlying tear tape 20 so that fusible tear tape surface 30 contacts a contact portion 31 of surface 32 of wrapping material 22. As the tear tape material 20 and wrapping material 22, now in contact over contact portion 31, passes around revolving drum 10, radiant energy at spot 16 passes through the wrapping material into tear tape 20, some of the energy is absorbed by fusible tear tape surface 30, raising the temperature of the fusible material at surface 30 to its melt point. As the contact portion 31 continues to pass around revolving drum 10, the melted portion of the fusible material at tear tape surface 30 passes out of the spot 16 and it cools, allowing fusible surface 30 to bind to the overlying wrapping material surface 32, forming finished tear tape packaging material 24.

The tear tape can have a laminate structure, such as is shown by way of example in Fig. 4. Tear tape 200 includes tear tape ribbon 240, made from a material having good tensile strength such as, for example, polypropylene, sandwiched between layers 242 and 244 of a fusible material such as, for example, ethylene vinyl acetate. Either fusible surface 243 of layer 242 or fusible ajurface 245 of layer 244 can be pressed into contact with wrapper surface 232 as the tear tape 200 and wrapper material 220 pass under tension over revolving drum 10, as described generally above with reference to Fig. 3. Such a layered tear tape 200 can be made, for example, by coextrusion.

The duration and intensity of exposure of the tear tape and wrapping material to the radiant energy at 16 can be controlled by regulating the intensity of energy at the source 12, the quantity of energy from the source that is brought by focussing into the spot at 16, and the rate of movement of the tear tape and wrapping material through the spot at 16. The force with which the tear tape and the wrapping material are pressed together during the exposure to the radiant energy can be controlled by regulating the tension on the wrapping material leading to the contact drum, and on the packaging material leading away from the contact drum.

The tear tape and wrapping material can be moved through the spot at 16, for example, by using a capstan 26 to draw the formed packaging material away from rotating drum 10, and the speed of capstan 26 can be increased or decreased to change the rate of linear movement of the packaging material, tear tape and wrapping material. Or, frictional forces resulting from contact of drum 10 with the tear tape, the wrapping material and the packaging material may prevent slippage, and so, alternatively, contact drum 10 can be rotated by a driver (not shown in the Figs.), and the rotation rate of contact drum 10 (and thus the rate of movement of the tear tape, etc.) can be controlled by controlling the speed of the driver. The tension on the wrapping material can be controlled for example by imposing a controlled resistance at the wrapping material supply, as by, e.g. , a brake or clutch resisting rotation of wrapping material supply spool 23; and a tension on ttte packaging material can be controlled by, eg. , a brake or clutch resisting rotation of contact drum 10, or by, eg. , increasing or decreasing the torque on capstan 26 (or, in the absence of a capstan, by, eg. , applying a greater or lesser torque on the takeup spool 25) .

Where, as is preferred and as is shown in the Figs., energy source 12 is an incandescent electric light, the energy intensity at the source 12 can be selected by selecting an incandescent bulb having a specified luminance, or can be regulated by regulating the electric current.

The quantity of energy from the source that is brought into the spot at 16 can be regulated by any of a variety of means for regulating radiant energy projection such as, for example, fixed or moveable lenses and lens systems (including variable focus systems), iris diaphragms, filters, and the like. Referring now to Fig. 5, tear tape 20 and overlying wrapping material 22 are shown passing over revolving drum 10. As any point P in contact portion 31 passes into and through spot 16, the fusible material at fusible tear tape surface 30 at that point warms to melt; and then, as the contact portion point P passes out from spot 16, the fusible material cools to fuse to wrapper surface 32 as described generally above with reference to Figs. 3 and 4. The size of spot 16 preferably is set sufficiently small relative to the width of the fusible tear tape surface so that the wrapper material adjacent the contact portion 31 is not warmed enough to cause distortion of its shape. Use

The method of the invention can be used for straightforward continuous manufacture of tear tape packaging materials. Any of various starting materials can be used, according to particular demands for the packaging. Processing variables such as energy intensity- and size of the energy spot at the fusible layer surface, duration of exposure of the materials to the energy, pressure exerted between tear tape and wrapping material, and the like can be selected according to the particular materials used.

Other Embodiments Other embodiments are within the following claims. For example, the radiant energy source and means for directing it toward a portion of the fusible can be a laser. The light source can be narrow bandwidth, to provide more effective heating of the fusible material without excessively raising the temperature of the overlying wrapper material. Infrared radiation can be used, but commercially available means for directing IR to a small spot are cumbersome and expensive.

Other materials can be used for the wrapper material, the tear tape ribbon, and the fusible material. The fusible material can be pigmented for improved or selective absorption of the radiant energy.

The tear tape can be passed over the drum between the wrapping material and the drum surface, or the wrapper material can be passed over the drum between the tear tape and the drum surface. The movement of, and control of tension in, the tear tape, the wrapper, and the finished tear tape packaging material can be automated. Preferably the wrapper material is not warmed above the point at which it begins to distort, namely, for example, about 300 °F (about 235-320 °F) for polypropylene.

Claims

1. A method for making a packaging material, including steps of providing a tear tape having a fusible surface, contacting the fusible tear tape surface with a surface of a wrapping material, and directing radiant energy toward a portion of the fusible surface.

2. The method of claim 1 wherein said radiant energy directing step comprises using a lens to focus illumination from an incandescent light source toward the fusible surface.

3. The method of claim 1 wherein said radiant energy directing step comprises directing laser energy toward the fusible surface.

4. The method of claim 1 wherein said contacting step comprises pressing together said fusible tear tape surface and said wrapping material surface.

5. The method of claim 1 or 4 wherein said contacting step comprises passing said tear tape and said wrapping material together upon a surface of a rotating drum, said fusible surface of said tear tape facing and contacting a contact portion of a surface of said wrapping material.

6. The method of claim 5 wherein said tear tape is passed between said wrapping material and said drum surface.

7. The method of claim 5 wherein said fusible tear tape surface and said wrapping material surface are pressed together by maintaining a lengthwise tension on said wrapping material.

8. The method of claim 1, further comprising controlling the temperature at said fusible tear tape surface.

9. The method of claim 8 wherein said controlling step comprises controlling the length of time in which said radiant energy is directed at .said portion of said fusible surface.

10. The method of claim 8 wherein said controlling step comprises controlling the intensity of said directed radiant energy.

11. The method of claim 4, further comprising controlling the force of said pressing together of said fusible tear tape surface and said wrapping material surface.

12. A packaging material made by a method including steps of providing a tear tape having a fusible surface, contacting said fusible tear tape surface with a surface of a wrapping material, and directing radiant energy toward a portion of said fusible surface.

13. A packaging material made by any of the methods o claim 1-11.

14. The packaging material of claim 12 wherein said wrapper material comprises a polymer film.

15. The packaging material of claim 12 wherein said wrapper material comprises polypropylene.

16. The packaging material of claim 12 wherein said tear tape comprises a tear tape ribbon having a coating of a fusible material on at least one surface.

17. The packaging material of claim 16 wherein said tear tape ribbon comprises a polymer.

18. The packaging material of claim 16 wherein said tear tape ribbon comprises polypropylene.

19. The packaging material of claim 16 wherein said fusible material comprises a polymer that is fusible at a temperature lower than the temperature at which distortions are produced in said wrapper material.

20. The packaging material of claim 19 wherein said fusible material comprises ethylene vinyl acetate.

21. Apparatus for making a tear tape packaging material, including a source of radiant energy, means for contacting a surface of a wrapping material with a fusible surface of a tear tape, and means for directing radiant energy from the source toward a portion of the fusible tear tape surface.

22. The apparatus of claim 21 wherein said source of radiant energy comprises an incandescent light.

23. The apparatus of claim 21 wherein said energy directing means comprises a lens.

24. The apparatus of claim 21 wherein said contacting means comprises means for passing said tear tape and said wrapping material together upon a surface of a rotatable drum.

25. The apparatus of claim 21, further comprising means for pressing together said fusible tear tape surface and said wrapping material surface.

26. The apparatus of claim 24 wherein said passing means comprises means for passing said tear tape between said wrapping material and said drum surface, further comprising means for providing a lengthwise tension in said wrapping material whereby said fusible tear tape surface and said wrapping material surface are pressed together.

27. The apparatus of claim 21, further comprising means for controlling the length of time in which said radiant energy is directed toward said portion of said fusible tear tape surface.

28. The apparatus of claim 27 wherein said contacting means comprises means for passing said tear tape and said wrapping material together upon a surface of a rotatable drum, and said length of time controlling means comprises means for controlling the speed of rotation of said drum.