US3750938A

US3750938A - Plastic closure for paper containers and metho of making same

Info

Publication number: US3750938A
Application number: US00106134A
Authority: US
Inventors: R Wiseman
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-01-13
Filing date: 1971-01-13
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07

Abstract

The present invention relates to a container such as a paper envelope having an access closed by a flap releasably held closed by plastic snaps comprising a first snap element securely bonded to the body of the envelope, and a second snap element securely bonded to the flap, said first and second snaps adapted to releasably attach to each other, with the snap elements each being directly bonded to the paper-like material, and formed for combined strength and efficiency of space. The invention also provides a method of making a plastic closure system directly on a paper envelope having a main body section and a closure portion, which comprises molding a thermoplastic element directly adjacent to the main body and bonded therewith during formation thereof, and molding a second and mating closure element on the closure portion by direct molding with a thermoplastic material and in contact with said closure portion.

Description

United States Patent 11 1 Wiseman 1451 Aug. 7, 1973 [76] Inventor: Robert F. Wiseman, 1227 Anza, San

Francisco, Calif. 941 18 [22] Filed: Jan. 13, 1971 [21] Appl. No.: 106,134

Germany 24/208 R Primary Examiner-Richard A. Schacher Att0rney-Schapp & Hatch [57] ABSTRACT The present invention relates to a container such as a paper envelope having an access closed by a flap releasably held closed by plastic snaps comprising a first snap element securely bonded to the body of the envelope, and a second snap element securely bonded to the flap, said first and second snaps adapted to releasably attach to each other, with the snap elements each being directly bonded to the paper-like material, and formed for combined strength and efficiency of space. The invention also provides a method of making a plastic closure system directly on a paper envelope having a main body section and a closure portion, which comprises molding a thermoplastic element directly adjacent to the main body and bonded therewith during formation thereof, and molding a second and mating closure ele ment on the closure portion by direct molding with a thermoplastic material and in contact with said closure portion.

6 Claims, 8 Drawing Figures PLASTIC CLOSURE FOR PARER CONTAINERS AND METHO OF MAKING SAME BACKGROUND OF THE INVENTION The present invention relates to a PLASTIC CLO- SURE FOR PAPER CONTAINERS AND METHOD OF MAKING SAME, and more particularly to such a construction where the plastic closure elements are made from thermoplastic resinous material.

It is well known to provide containers and envelopes made from paper or cardboard, and where an envelope is to be used once and then discarded, it may be sealed by any suitable means and torn open for use. However, where it is desired to use the envelope over a period of time and have access to material contained therein, it is necessary to either leave the envelope unsecured or to provide a temporary closure system which may be opened and closed as desired. It is this letter type of closure to which the invention is directed.

One of the most frequently used envelopes of the class described contains a metal fastener, which is punched through, secured to the main body of the paper, and adapted to have a pair of bendable prongs extend through a reinforced hole in a flat portion thereof. While these closures are eminently suited for the purpose, certain disadvantages have been encountered, particularly in the cost of fabrication thereof. First of all, in order to punch the fastener to the envelope it is necessary for the machine to separate the two adjacent sheet portions so that the metal element may be punched through and secured without fastening the entire envelope in a closed relation. In addition, it is necessary to reinforce the hole so that this closure will retain the envelope in a closed position rather than causing the flap to tear away. The difficulties encountered in securing the fastener are such that it requires a costly machine, and even with costly machines breakdowns frequently occur.

Another problem that has been encountered with envelopes of this kind resides in the fact that after a limited use the metal prongs break. This is caused by the necessary bending of their metal during the opening and closing operation. Efforts to solve such problems have heretofore lead to more expensive and more bulky elements such as the string closures now in use.

The use of snap elements on envelopes tends to render the device more suitable for large numbers of opening and closing operations, but heretofore snap elements were difficult or expensive to apply to the envelope. These problems are overcome by the method aspect of the present application. In addition, the present invention also provides for an improved plastic closure element having certain advantages that will be apparent as the specification progresses.

SUMMARY OF THE INVENTION From the above description it is seen that a primary object of the invention is to provide a closure for paperlike envelopes or the like which is simple and inexpen sive to fabricate and capable of heavy usage over a considerable length of time.

Snap elements have been conventionally applied to cellulosic textile materials by sewing and the like, and this is true even with plastic snap elements. Another method of attachment resides is providing keep ers that are permanently secured to grip a portion of the material and retain the fastener in place. Such systems are suitable for relatively strong textile materials, but are not satisfactory for securing'the fasteners to paper materials.

Due to the advent of superior adhesive materials, it is possible to secure plastic snap elements to paper and the like by using such adhesives. However, the placement of adhesive on individual snap elements and the location of the elements on the envelopes is a relatively costly operation. These problems are overcome by applicants method of molding the snap element in place so as to form the element in contact with the cellulosic material, and obtain adherence by utilizing certain of the socalled hot melt thermoplastic materials for molding that are capable of adhering to paper when heated to the plastic state.

Practically all of the thermoplastic materials which are capable of being softened without decomposition and cast could be used to form snap elements adjacent to the paper product. However, it has been found that materials such as polyethylene and related polyolefins, which do not contain polar groups generally do not provide the desired adherence to paper products. However, thermoplastic materials having sufficient polar groups thereon to bond with the paper form excellent adhesive characteristics so that when the snap element is formed adjacent to the paper, it cannot be removed withouttearing off at least a surface layer of the paper withit. Accordingly, the securin gefiect is as strong as the paper itself. This is true of certain oxygenated thermoplasic resins such as vinyl acetate copolymers, and a preferred plastic is a typical commercially available copolymer of ethylene and vinyl acetate sold as a hot melt. i

In addition to thermoplastic resins with polar groups, thermoplastic materials containing an adhesive ingredient as a physical component therein may be used. Many such hot melt items are readily available on the market, and the adhesive properties are well known in the plastic art. Accordingly, many materials are available which have the desired physical properties. i

In order to utilize the typical hot melt" materials available on the market, it is preferred to utilize the special pair of molds which may be attached to a typical envelope machine so as to mold the desired fastening elements in position, rather than attach an element as now accomplished by such machines. Accordingly, a relatively simple modification of present machinery is possible, because the handling of the envelopes during application of the closure elements would be the similar. In other words, the machines are modified by the addition of a suitable molding device, which will cast on the adhesive to the paper envelope in the desired places to form the desired fastening elements. Although a typical fastening system would involve two elements such as a male and female snap element, it will be appreciated that more than one pair of such elements may be provided if desired. It will also be appreciated that various forms of securing elements may be utilized such as letters or simple trademark symbols, if desired.

In its method form, the plastic is heated and applied through a typical melting machine such as devices utilized for spraying hot melt or the like and passed down into a molding head which in turn is placed adjacent to the envelope. A desired amount of hot plastic is metered through the mold, the mold stamped down so as to form the snap element firmly on the paper, and then the mold is then pushed away from the paper preferably by a self-yielding system such as springs to clear the mold from the device. By selecting the proper temperatures of the mold and hot melt, the snap element will set up almost immediately upon removal, but settle in a little as it cools to form a sufficiently tight snap pocket prior to final hardening.

The hot metal material should not only adhere to the paper, but it preferably should have a sufficiently high melting point that it will not become tacky under using conditions and may be readily separated as desired with snap elements. If desired, a suitable powder may be applied over the molded product immediately after formation in order to provide a more suitable non-sticky surface.

From the above description, it is seen that snap elements may be molded directly to the paper and thus provide a new article of manufacture, namely an envelope-like construction containing snap elements directly bonded to the flat surfaces thereof. In addition, the snap elements may assume any desired configuration, and the preferred form of the invention utilizes snap elements having reinforcement sections so as to protect the edge of the flap of the envelope from tearing use. If desired, a tab may be placed on the snap element to'provide an element to assist in opening the snaps. Accordingly, certain preferred closure structures are also provided by the present invention.

It is also desired to utilize snap elements that are comparatively thin and have very little base thickness. This is made possible by the fact that the snap becomes integral with the envelope and the envelope paper in effect can become part of the snap body. By making snaps relatively thin (i.e., having a thin floor section), an envelope is provided which is more readily stored than one that would contain conventional snap elements thereon. From the above description, it is seen that another object of the invention is to provide an improved envelope having a .special snap closure construction formed therewith.

A further object of the invention is to provide a method of manufacturing envelopes or the like having closure elements thereon utilizing envelope handling machinery somewhat similar to that now in use, but modified to provide an improved construction.

Further objects and advantages of the invention will be apparent as the specification proceeds and the new and useful features of the plastic closure for paper container and method of making same will be more fully defined in the claims attached hereto.

BRIEF DESCRIPTION OF THE DRAWING The preferred forms of the invention are illustrated in the accompanying drawing, forming a part of this description, in which:

FIG. 1 is a perspective view of a typical envelope constructed according to the invention;

FIG. 2, an enlarged fragmentary view of the envelope as seen in FIG. 1; FIG. 3, an enlarged, fragmentary, cross-sectional view of the envelope through the fastening means illustrating the construction of the fasteners in the open position;

FIG. 4, a view similar to that shown in FIG. 3, but illustrating the fasteners in a closed position;

FIG. 5, a plan view, partly in cross-section, illustrating a typical mold that may be utilized to carry out the method aspect of the invention;

FIG. 6, an envelope similar to that shown in FIG. 1, illustrating a modified form of the invention;

FIG. 7, a view similar to that shown in FIG. 6, but illustrating still another embodiment of the invention; and

FIG. 8, a perspective view illustrating yet another modification of the invention.

While only the preferred forms of the invention are shown and described in detail, it should be understood that various changes or modifications may be made within the scope of the claims attached hereto without departing from the spirit of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing in greater detail and particularly to FIGS. 1 through 4, there is shown an envelope 11 formed in a typical flat arrangement with a pair of flat body members enclosing a space therebetween by virtue of having three closed sides, and a flap 12 adapted to fold over the main body 13 for completing the closure. As used herein, the term envelope is construed to mean any container capable of providing a complete enclosure and includes the box-like configuration shown in FIG. 8 as well as the preferred folded flat form shown in FIG. 1. However, the envelopes of this invention are composed of non-woven cellulosic material typically formed into paper or cardboard. Such envelopes have the advantage of being inexpensive and enjoy widespread usage because of their practical advantages.

Rererriagtigaifi to FIGS.'Ithrouglil'tliere is shown a pair of

snap elements

14 and 16, with snap element 14 being located on flap 12 and snap element 16 being located on the main body 13. As shown herein, the female element 14 is located on the flap and the male element 16 is located on the main body of the envelope, but it will be appreciated that the parts may be re versed, if desired, without departing from the spirit of the invention.

Referring more particularly to FIGS. 3 and 4, it is seen that

snap elements

14 and 16 are each directly bonded to the paper without use of adhesive or otherwise. As shown in the drawings, an extending coating or

floor portion

17 and 18 is provided on each of the snap elements in order to provide a stronger attach ment and reinforce the strength of the paper at the position of the fastener.'Preferably, this portion is made relatively thin as are the connecting

elements

19 and 21 in order to prevent undue thickness in the snap elements. However, male element 19 and female element 21 should be large enough to provide the desired securing forces. Although a typical circular snap form is here shown, it will be appreciated that the form the snap element takes may vary in accordance with design desires, and circular shape shown is for illustration only.

In its method form, the invention comprises the steps of providing and heating a thermoplastic material above the softening point and to its plastic state, preferably to the state of hot melt as is well known in the art. Applying the plastic in the hot melt form through a typical delivery apparatus such as the apparatus 22 which is formed to deliver a spray-like liquid of thermoplastic material when a nozzle is positioned in place of the typical mold element 23 as shown in FIG. 5. The softened thermoplastic material is then formed onto sheet 12 as shown in FIG. 5, the mold element 23 retracted, and formation of a snap element 14 is completed.

Referring more particularly to the apparatus shown in FIG. 5, a spray head for delivery of liquid resin is available commercially and provides a passageway 24 for discharging melted resin at a controlled temperature. The machine is modified by providing a mold element 23, which is held in place by bushing 26. The bushing 26 is also formed to provide a stop and retain skirt 27 from coming off the mold. Skirt 27 is urged outwardly toward the stop by compression spring 28, and this action is used to normally retract the mold from sheet 12.

In operation, the mold 22 is pushed downward so that skirt 27 first moves against the sheet 12 in the desired location, a metered amount of heated plastic is then supplied through passage 24, the mold is then depressed to form an element such as element 14, and the mold is allowed to retract by action of spring 28 to separate the mold from the snap element formed on the paper. If desired, the entire mold configuration may be made in mold element 23, or the outer portion of the mold element may be a portion of bushing 26 so as to allow the mold area to reach the area defined by skirt 27.

It will be appreciated, that machines presently. set up to handle envelopes and place metal fasteners and reinforcing rings thereon may have suitable molds substituted at the proper location and utilized for providing snap elements on the envelope in accordance with the present invention. It will Also be appreciated that the mold elements may be made interchangeable so that different designs of snap elements may be provided from substantially the same machines, with only minor changes necessary. Certain different embodiments of snap elements are illustrated in FIGS. 6 through 8, where certain constructional advantages are also provided.

Thus, referring now to FIG. 6, there is shown an envelope 11a having a pair of

snap elements

14a and 16a with the snap element 14a being provided with a tab portion 31. This tab 31 is utilized to enable the user to obtain a more ready grip on the snap for opening same.

In FIG. 7, there is shown another modified envelope 11b equipped with snap elements 14b and 16b. Snap element 14b has its floor section 17b thereof extending to the edge of the flap near the fastener from tearing.

In FIG. 8, there is shown an envelope 11c in the form having the ability to bond with paper, with each snap of a box-like configuration, with the flap 12c being equipped with the snap element similar to snap element 14 of FIG. 1, while the body portion 13c is a snap element 16c similar to the snap element 16 of FIG. 1. It will also be appreciated that other design modifications may be made, if desired, but it is believed that those modifications shown are illustrative of the various forms of paperlike containers utilized in the present invention.

From the above description, it is seen that I have provided a novel plastic snap which is directly mounted to a paper-like container to provide an improved temporarily closable envelope, and that I have provided a new and useful method of makiuG same.

I claim: I

1. In a paper envelope having a main body and a flap member, in combination; a plastic closure means, comprising a first snap element securely bonded directly to the body of the envelope, and a second snap element securely bonded directly to the flap member of the envelope and adapted to releaseably attach to said first snap element, said snap elements each being formed substantially in their entirety of the thermoplastic resin element being directly heat bonded to the envelope.

2. A paper envelope as defined in claim 1, in which each element is formed with a thin floor section for providing secure attachment to the: paper, and in which the thickness of each snap element is minimal, whereby flat envelopes may be stacked in close proximity to each other.

3. A paper envelope as defined in claim 2, in which the floor portion of the second element has an edge corresponding with the edge of the flap for a distance substantially the width of the snap element for providing reinforcement in the area of strain during opening of the snap.

4. A paper envelope as defined in claim 1, in which a tab is formed of thermoplastic material, with said tab being provided on the second snap element for use in opening the snaps.

5. A paper envelope as defined in claim 1, in which the envelope is of flat configuration with the main body portion comprising two sheets of paper in face-to-face orientation, and in which the edges of the snap elements are tapered at their line of juncture with the paper.

6. A paper envelope as defined in claim 1, in which the envelope is of a box-like configuration.

Claims

1. In a paper envelope having a main body and a flap member, in combination; a plastic closure means, comprising a first snap element securely bonded directly to the body of the envelope, and a second snap element securely bonded directly to the flap member of the envelope and adapted to releaseably attach to said first snap element, said snap elements each being formed substantially in their entirety of the thermoplastic resin having the ability to bond with paper, with each snap element being directly heat bonded to the envelope.

2. A paper envelope as defined in claim 1, in which each element is formed with a thin floor section for providing secure attachment to the paper, and in which the thickness of each snap element is minimal, whereby flat envelopes may be stacked in close proximity to each other.