WO1999062366A2

WO1999062366A2 - Biodegradable fastener and method of manufacture of same

Info

Publication number: WO1999062366A2
Application number: PCT/US1999/012471
Authority: WO
Inventors: Orville Spence; Thomas E. Schostek
Original assignee: American Excelsior Corp
Current assignee: American Excelsior Corp
Priority date: 1998-06-04
Filing date: 1999-06-04
Publication date: 1999-12-09
Anticipated expiration: 2000-12-04
Also published as: WO1999062366A3; AU4417999A

Abstract

A biodegradable fastener capable of securing and fastening together one or more objects. The biodegradable fastener is misted or otherwise contacted with water to initiate tackiness and upon application of pressure adheres to the one or more objects and/or to itself. Disposal of the fastener is safe, quick, easy and inexpensive since the fastener is biodegradable. Accordingly, once the bound objects are no longer desired, they can be disposed with the knowledge that prolonged contact with water will naturally breakdown the fastener into its constituent components. Use of the biodegradable fastener to fasten together one or more objects further provides evidence of tampering with the desired positional relationship of the fastened objects, making the biodegradable fastener ideal for use with packages or containers including foodstuff, pharmaceuticals and the like.

Description

BIODEGRADABLE FASTENER AND METHOD OF MANUFACTURE OF SAME

TECHNICAL FIELD

The present invention relates to fasteners, and more specifically, to a biodegradable fastener capable for use in fastening and securing together one or more objects, and a method of manufacture of same.

BACKGROUND OF THE INVENTION

Numerous adhesives and devices have been developed for use in connection with arranging and securing various components together. From pressure-sensitive tapes to hot-melt adhesives, most, if not all, of these prior art devices suffer from significant disadvantages. A typical type of fastener includes the use of an adhesive or tackifying agent capable of sticking to objects to temporarily or permanently bind them together. However, use of such prior art fasteners, such as transparent, insulating and double- sided tapes, presents certain disadvantages. For example, although flexible in nature, common adhesive tapes are limited in their ability to mold to certain shapes. Additionally, the tackiness of adhesives and other tackifying agents can diminish with time and under certain environmental conditions, rendering traditional tapes ineffective.

Importantly, the paper and/or thermoplastic carriers or backings used with prior art fastening devices are made from non-renewable sources, such as trees. Waste storage concerns are also associated with use of such traditional tape materials. Proper disposal of such objects requires that the tape either be removed prior to disposal or otherwise treated in an effort to limit the adverse affects such adhesives and materials can have on the environment.

The use of hot-melt adhesives also presents significant disadvantages. As the name suggests, heat is required to activate adhesives used in this type of traditional fastener. The use of heat not only requires additional equipment, increases costs, limits applications and poses safety concerns, it also produces noxious and/or toxic fumes during its applicant and use. Additionally, the guns required to apply such adhesives frequently clog, jam and otherwise produce inconsistent results. Application guns frequently leak, creating an unsafe work environment and interrupting normal operating procedures. Moreover, users of the application guns often experience strain and associated pain (e.g., carpal tunnel syndrome) from the repetitious motions required to apply such adhesives. Such increased complexity and safety concerns are evidenced by the strict requirements imposed by OSHA for use of such adhesives. Finally, environmental concerns associated with the disposal of such products outlined above also exist for this type of fastener.

The prior art fasteners discussed above also lack an ability to indicate package tampering. For example, a traditional adhesive-based tape used to seal a carton or package can easily be removed and replaced in a manner that avoids detection, rendering the contents of the carton or package vulnerable to tampering. This is of particular concern where the contents of the carton or package are, or include, food stuffs, pharmaceuticals, or the like.

Finally, all of the above-identified prior art fasteners potentially create aesthetically displeasing results. This is due primarily to the fact that the tapes and/or adhesives are visible, disrupting exterior patterns, artwork, graphics or similar decoration and/or the natural appearance of the objects with which the fasteners are being used.

In view of the above, it may be seen that there remains a need for an inexpensive, safe and relatively permanent device capable of securing and fastening objects together without the need for special applicators and/or complicated and expensive activation steps. Such a desired fastener would also be comprised of renewable materials, would provide evidence of tampering, and would be effective without the production of harmful or noxious fumes. It would thus be a marked advance over the prior art to provide an apparatus for securing and fastening objects which did not exhibit the use and disposal concerns associated with the prior art. SUMMARY OF THE INVENTION

The present invention provides a starch-based biodegradable fastener in the form of a tape which can be used to quickly and easily secure and fasten objects to each other, and a method of manufacture for same. The biodegradable fastener of the present invention safely and securely fastens an object or objects together without the need for adhesives, application guns or similar devices or other tackifying agents. Use of the biodegradable fastener of the present invention does not create fumes or otherwise harm the applicator, the environment and/or others. Since the biodegradable fastener is the material itself, the fastener can be used as a single-sided or double-sided fastener. Accordingly, most applications of the biodegradable fastener will not disrupt the aesthetics of the objects with which the fastener is being used. Moreover, the biodegradable fastener of the present invention is made of a renewable material (corn starch) and, since the fastener is biodegradable, environmental disposal concerns are eliminated. Importantly, the biodegradable fastener of the present invention provides evidence of package tampering.

Using recently-developed extruding techniques, sheets of biodegradable material can be formed having thicknesses as small as 1/64" can be produced. As with paper products, the resultant sheet material can be colored using dyes and/or printed upon via traditional techniques, if desired. Therefore, transparent, translucent and opaque embodiments of the fastener are easily manufactured. The sheet material is subsequently cut into strips that are wound onto rolls to be used as a continuous fastener. Like tapes, the continuous fastener is cut, torn or otherwise separated into desired lengths for use.

In use, the fastener of the present invention is unwound from a roll and positioned around and/or between the object or objects to be secured and/or fastened together or to another object. Once the object or various objects are positioned into a desired positional relationship, the fastener is exposed to water (e.g., via misting) so as to tackify it. This tackification "freezes" the desired relative position of the object or various objects into place. At a time when the bound items are no longer desired, the object(s) including the tape material can be easily and safely discarded without removal of the tape material since subsequent contact with large amounts of water in a landfill or otherwise over a long period of time will cause the safe breakdown of the fastener into its constituent components. Unlike the use of traditional tape products, presence of the tape material prior to breakdown will not present any environmental hazard.

Finally, since the tape material dissolves into the material of the elements to be fastened (e.g., cardboard box lids) upon tackification, evidence of tampering with a carton or package sealed using the tape material of the present invention is present. It is virtually impossible to remove all of the dissolved tape material from the elements.

BRIEF DESCRIPTION OF THE DRAWING

For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawing in which: FIGURE 1 is a perspective view of an embodiment of the fastener of the present invention;

FIGURE 2 is a perspective and progressive view of a fully-overlapping box, its flaps being secured with the fastener of the present invention;

FIGURE 3 is a perspective and progressive view illustrating use of the fastener of the present invention as a non-slip interleaver used in connection with palletizing; and

FIGURE 4 is a flowchart illustrating the steps of the method of manufacture of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIGURE 1 , there is shown an embodiment of the biodegradable fastener of the present invention. In a preferred embodiment, the biodegradable fastener 10 is composed of a starch-based biodegradable material described more fully below.

Many types of biodegradable materials are known in the art. One of the more common and commercially successful biodegradable materials are comprised of starch- based compounds. Typically, these compounds are comprised of one or more modified high-amylose starch components. One advantage associated with the use of such materials is that dyes and other additives can be used to impart desired characteristics such as color and texture, for example. High amylose starches are used to impart resilience and compressibility to the material. The addition of polyvinyl alcohol ("PVA") is also known to increase the flexibility of starch-based biodegradable materials.

Starch is a polysaccharide typically comprising a mixture of about 20-25% amylose and about 75-80% amylopectin which is organized into compact granular structures. Amylose is a linear polymer of D-anhydroglucose units which are linked by alpha- 1 ,4-D-glucosidic bonds. High-amylose starch is starch containing at least 45% by weight amylose content. Modified starch is starch derivatized or modified by processes known in the art, such as etherification with alkylene oxide.

Starch-based biodegradable materials are typically produced by mixing one or more components to form a material. Subsequently, the material is extruded and/or cut into a desired shape and/or size. A method is now known for extruding a starch-based biodegradable materials of less than about 1/8" in thickness. Such method is more fully described in co-pending application Serial No. 08/816,929, assigned to the American Excelsior Company of Arlington, Texas.

In a preferred embodiment, the starch-based material is cut into a strip approximately 1-3 inches in width, although the optimal width is determined by the desired application. In a particularly preferred embodiment, the starch-based material strip measures approximately 1 Vi inches in width. The continuous strip is preferably wound onto a roll 20 of length of several feet, depending upon the application. As with traditional tape dispensers, a serrated edge or otherwise sharpened edge or surface (not shown) is preferably provided so that the fastener 10 easily can be cut by the user into desired lengths.

Still referring to FIGURE 1, prior to use the biodegradable fastener 10 of the present invention is cut to a desired length and moistened. Preferably, the length of fastener 10 is brushed with a small amount of water 30. Although brushing the fastener 10 length with a small amount of water 30 is preferred, the fastener can be sprayed, misted or otherwise contacted with a relatively small amount of moisture. The small amount of moisture, especially when coupled with light pressure applied to the fastener 10, initiates tackiness of the fastener material and allows the fastener 10 to firmly adhere to various objects and/or itself to facilitate securing and/or fastening the various objects together or to other objects. The level of tackiness produced can be controlled through the introduction of varying amounts of water and/or the amount of pressure applied to the fastener upon contact with another surface. Alternatively, the biodegradable fastener 10 can be placed in, around and between various objects before tackification is initiated.

Now referring to FIGURE 2, wherein like components are designated with like reference numerals, there is shown an example of use of the fastener 10 in connection with one or more securing flaps 40 of a fully-overlapping ("FOL") box 50. An example of FOL box 50 is a cereal box for the containment of cereals, such as breakfast cereals. Predetermined lengths of the fastener 10 are prepared to facilitate securing the flap 40 of the FOL box 50. The lengths can be cut, torn or otherwise separated from a roll 20 (FIGURE 1) of the fastener 10. The lengths of fastener 10 are first brushed with a small amount of water 30 (FIGURE 1) to initiate tackiness of the material. Next, the lengths of fastener 10 are placed along the inside area which the flap 40 will contact the FOL box 50 when the flaps 40 are closed. Once contacted with water 30 (FIGURE 1), the lengths of fastener 10 are tacky and will adhere to the FOL box 50. Next, the flap 40 of the FOL box 50 is folded down to contact the length(s) of fastener 10. By applying light pressure to the flap 40 in the closed position, the flap 40 is adhered to the tackified fastener 10, thus securing the flap 40 to the top of the FOL box 50. Once contacted with water 30 (FIGURE 1) and pressure, the fastener 10 transforms from a solid material into a gel which is then absorbed by the material of the FOL box 50. Subsequently, the fastener 10 resets into a solid material, creating the bond which secures the flap 40 of the FOL box 50. It is noted that absorption of the fastener 10 material by the box material does not prohibit repulping of such material, but does provide evidence of package tampering.

Use of the fastener 10 with cereal boxes or containers and the like is particularly preferred since the fastener 10 does not need to provide a moisture-resistant seal, but preferably provides clear evidence of tampering. Currently, hot-melt adhesive and application guns are routinely used to secure the cartons of cereal boxes. The expense, complexity, regulatory-compliance and safety concerns associated with the use of hot- melt adhesive fastening methods noted above are avoided with use of the fastener 10 of the present invention.

When use of the FOL box 50 is no longer desired, the FOL box 50, along with the fastener 10 can be easily and safely discarded. Since the fastener 10 is composed of biodegradable material, it will dissolve into its constituent components upon prolonged contact with a large amount of water. Since a relatively large amount of water and an extended period of time is needed to initiate natural breakdown of the fastener 10, concerns over premature opening of the FOL box 50 is effectively minimized.

The biodegradable fastener 10 of the present invention can be used without prior planning and concern of clean up once its disposal is desired. The water-soluble biodegradable fastener material dissolves upon contact with a sufficient amount of water and over an extended period of time, thereby making disposal a simple, natural and environmentally safe process. This feature of the invention allows the fastener 10 and/or the objects including the fastener (e.g. , FOL box 50) to be discarded, if desired, without worry of environmental contamination and/or danger to others. If one or more fastened objects are desired for retention and/or reuse, the object(s) can be contacted with a sufficient amount of water (e.g., saturated) for an extended period of time so that the fastener material will dissolve, leaving the object(s) unharmed and available for retention or reuse.

Importantly, use of the fastener 10 will provide evidence of tampering. During tackification, the tape material dissolves into the flap 40 of the FOL box 50. If the seal of the FOL box 50 is tampered with prior to its desired use, there will remain a certain amount of the tap material to evidence the tampering event. If desired, the use of color additives, etc., can be used to emphasize this feature of the fastener 10. Therefore, even if attempts are made to remove and replace the tape material with the same or another fastener, identifying signs of the original tape material should remain to evidence the attempt(s).

It is noted that although a FOL box is described above, the biodegradable fastener 10 of the present invention can be used in connection with any number of containers, including, without limitation, center special overlap containers ("CSOC"), center special slotted containers ("CSSC"), one piece folders ("OPF"), regular slotted containers ("RSC") and the like.

Now referring to FIGURE 3, wherein like components are designated with like reference numerals, there is illustrated an example of use of the biodegradable fastener 10 as a non-slip interleaver for palletizing various articles 60, such as bags or boxes. Here again, predetermined lengths of the fastener 10 are prepared to facilitate securing the articles 60 to be placed on a pallet 70. The lengths of fastener 10 can be cut, torn or otherwise separated from a roll 20 (FIGURE 1) of the fastener 10. The lengths of fastener 10 are first brushed or otherwise contacted with a small amount of water 30 (FIGURE 1) to initiate tackiness of the material. Next, the lengths of fastener 10 are placed between the layers of articles 60 being palletized. Once contacted with water 30 (FIGURE 1), the lengths of fastener 10 are tacky and will adhere to the bottom of articles 60 to form the next layer to be placed upon the pallet 70. By applying light pressure to the next layer of articles 60 once they are placed over the positioned and tackified fastener 10, the articles 60 forming the top layer are adhered to the layer of articles 60 immediately below it, thus securing the layer of articles 60 to the pallet. Likewise the fastener 10 can be positioned and used directly on the pallet 70 to adhere and secure the first row of articles 60 to be palletized.

According to the method of manufacture of the present invention, the process preferably includes the use of a continuous extrusion process using extruders known in the art. In a preferred embodiment, an intermeshing, self-wiping, co-rotating, twin screw extruder is utilized in the process. Since the advantageous physical properties of the biodegradable fastener material of the present invention depend in part upon proper and complete mixing of the raw components, exact feeding, mixing, heating and cooling within the process is crucial to the process. Although an intermeshing, self- wiping, co-rotating, twin screw extruder is described, it should be noted that any appropriate type of extruder, such as a single screw type extruder for plastic, can be utilized.

As illustrated in FIGURE 4, first, if color is desired, food grade dyes and/or colors are provided in preferable amounts of between 0.01% and 2% in step 10 to achieve desired transparency, or lack thereof. Food grade dyes are selected since the resultant fastener material is biodegradable, although other dyes could be used, if desired. In the event color is added, the percentage amounts of the additional components are adjusted accordingly. In step 20, from between 0% and 20%> of modified or unmodified starch is provided. Next, high amylose modified starch is provided in a range of between 60% - 90% in step 30. The foregoing components are preferably provided in their dry form. The modified starch is preferably a high-amylose starch of approximately 70% amylose content modified with propylene oxide.

In step 40, from between 10% and 20%, and preferably between 10% and 15% of poly vinyl alcohol is provided as a component. Although a biodegradable material capable of being formed into a sheet is produced throughout the range of PVA listed above, the optimum percentage observed is between 12% and 12.5%. A substantially hydrolyzed PVA, for example, Airvol 325™ by Air Products and Chemicals, Inc. of Irving, Texas, is used. Airvol 325™ is fully hydrolyzed (98.0%-98.8%) and has a viscosity of 28.0 - 32.0 cps (a 4% aqueous solution at 20°C) and a pH of between 5.0 - 7.0.

In the next step of the process, step 50, the components are mixed in the extruder along with tap water. The resultant mixture is then heated to a temperature of between 190° F and 400° F before it is kneaded and sheared and extruded using a die in step 60. Much of the heat is provided by pressure exerted on the material by the extruder during the previous steps. These steps are preferably performed by a continuous process extruder, but could be achieved manually, if desired. Due to the unique formulation of the biodegradable material, the extrudate balloons out of the die, forming the thin sheet size of the biodegradable material of less than 1 /8 " .

In step 70, the extrudate is cooled and cut to a desired size(s) and shape(s), preferably a continuous strip of from between 1 and 3 inches wide. Subsequently, the fastener is wound onto a roll or dispenser. These steps of the process can likewise be accomplished by one or more of any means known within the art. Although preferred embodiments of the invention have been illustrated in the accompanying drawing and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements and modifications of parts and elements without departing from the spirit of the invention.

Claims

WHAT IS CLAIMED IS:

1. A biodegradable fastener capable of securing in place and fastening together in a desired relational position one or more objects, comprising: a high amylose starch component; from about 8% to 20% by weight of poly vinyl alcohol; and said fastener having a thickness of less than 1/8".

2. The biodegradable fastener of Claim 1, wherein the amylose starch component contains at least 45% by weight amylose.

3. The biodegradable fastener of Claim 2, wherein the amylose component is further modified with up to 15% by weight of alkylene oxide containing from between 2 and 6 carbon atoms.

4. The biodegradable fastener of Claim 2, wherein the amylose component is further modified with from about 10%) to 15%) by weight of poly vinyl alcohol.

5. The biodegradable fastener of Claim 4, wherein the starch component contains at least 70% by weight amylose.

6. The biodegradable fastener of Claim 2, wherein the starch component is modified with propylene oxide.

7. The biodegradable fastener of Claim 4, wherein the poly vinyl alcohol is hydrolyzed or substantially hydrolyzed.

8. The biodegradable fastener of Claim 1 , wherein the fastener comprises from about 60% to 90% by weight of the starch component.

9. The biodegradable fastener of Claim 1 , wherein the width of the fastener is from between 1 inch and 3 inches.

10. The biodegradable fastener of Claim 1 , wherein the width of the fastener is approximately 1 V_ inches.

11. The biodegradable fastener of Claim 1 , wherein the fastener can be tackified when contacted with a small amount of water.

12. The biodegradable fastener of Claim 1, wherein the fastener will substantially dissolve upon prolonged contact with a large amount of water.

13. The biodegradable fastener of Claim 1, wherein the fastener is comprised of natural and renewable materials.

14. The biodegradable fastener of Claim 1 , wherein application and use of the fastener does not produce noxious or toxic fumes.

15. The biodegradable fastener of Claim 1 , wherein the high amylose starch component provides evidence of tampering with the relational position of the fastened objects.

16. A method for forming a biodegradable fastener having a thickness of less than about 1/8", comprising the steps of extruding a composition comprising a high amylose component and from about 8% to 20% by weight of poly vinyl alcohol in the presence of a total moisture content of from about 25% or less by weight and at a temperature of from about 88 °C to 250° C.

17. The method of Claim 16, wherein the high amylose component contains at least about 45% by weight amylose.

18. The method of Claim 17, wherein the high amylose component is further modified with up to about 15% by weight of alkylene oxide containing from 2 to 6 carbon atoms.

19. The method of Claim 17, wherein the high amylose component is modified with from about 10% to 15%> by weight of polyvinyl alcohol.

20. The method of Claim 17, wherein the high amylose component contains at least 70% by weight amylose and is further modified with propylene oxide.