WO2011056400A1

WO2011056400A1 - Insulated double-walled disposable plastic cup

Info

Publication number: WO2011056400A1
Application number: PCT/US2010/053037
Authority: WO
Inventors: Qiuchen Peter Zhang; Liguo Zhao
Original assignee: The Coca-Cola Company
Priority date: 2009-11-04
Filing date: 2010-10-18
Publication date: 2011-05-12
Also published as: US20100108693A1; AR079605A1

Abstract

A thermally insulated double-walled disposable plastic container includes a container body having an inner cup and outer cup fixedly separated by an insulating space. The thermally insulated double-walled disposable plastic container is open at the top and enclosed at the bottom. The insulating space includes a gas for providing thermal insulation. A preferred gas is air. Preferred methods for making the insulated disposable double-walled plastic container includes blow-molding, thermo forming or injecting molding an inner cup and outer cup then fixedly connecting the inner cup and outer cup to define an insulation space there between.

Description

INSULATED DOUBLE-WALLED DISPOSABLE PLASTIC CUP

FIELD OF THE INVENTION [0001] The present invention generally relates to disposable plastic containers, and more particularly to thermally insulated disposable plastic containers. More specifically, the present invention relates to double-walled thermally insulated disposable plastic containers. BACKGROUND OF THE INVENTION

[0002] The production and use of thermally insulated disposable containers, such as cups, are well known and highly desirable. Thermally insulated disposable cups are generally useful for both hot and cold beverages. They are designed to maintain the beverage temperature by preventing undesirable heat transfer via the beverage inside the cup to/from the atmosphere or cup holder's hand. Currently available thermally insulated disposable cups are generally made from paper, polymeric materials or combinations thereof. [0003] Paper-based materials are generally favored for disposable cups, because of low cost and high volume production capability. However, paper- based materials generally do not have good barrier properties to liquids. Disposable cups made from such paper-based materials, have a tendency to decompose due to liquid penetration into the paper material, which can cause the cup to loose its structure and become soggy or leak. Furthermore, cups made from paper-based materials generally do not provide adequate thermal insulation and have limited product visibility.

[0004] There have been many attempts to provide improved thermal insulation to paper-based disposable cups. U.S. Pat. No. 5,226,585 to Varano discloses a double-walled disposable cup made from paper-based materials, which has a smooth walled inner cup and an outer wrap with inwardly directed ribs being useful to maintain a gap between the walls to provide thermal insulation. However, these cups are difficult and expensive to manufacture. They also tend to exhibit liquid barrier problems, which compromise the structural integrity of the cup.

[0005] U.S. Pat. No. 5,145,107 to Silver et al. teaches a double-walled thermal insulated disposable paper cup having an inner wall connected to an outer wall at the lip and at the base of the cup. The walls have different tapers which define an air pocket between the two walls. The air pocket is meant to provide thermal insulation. However, as with currently available paper-based disposable cups, structural integrity and product visibility remain a disadvantage.

[0006] Polymeric materials, such as polypropylene, polyethylene terephthalate (PET) based polyesters and polystyrenes have been widely used as container materials for disposable containers because of their improved mechanical and barrier properties. They also provide for product visibility. Numerous methods of producing disposable plastic beverage bottles and cups are disclosed in the prior art. However, containers made from such plastic materials do not provide adequate thermal insulation. Foamed polystyrene cups provide adequate insulation but are not good for recyclability and don't provide transparency.

[0007] Accordingly, there is a need for a disposable container that provides excellent thermal insulation and barrier properties and is recyclable. It would also be desirable to see the inside of the container from the sides of the container, thereby having better visibility of the product contained therein. In paper based or foamed polystyrene containers, in order to see the contents inside, it is necessary to look through an opening, for example by removing a lid, which could result in spills or additional heat transfer via the opening. Accordingly, it would be desirable to provide a transparent thermally insulated disposable plastic container.

SUMMARY OF THE INVENTION [0008] The present invention relates to a thermally insulated double-walled disposable container made from polymeric materials useful for containing hot or cold products and liquids. Thermally insulated double-walled disposable containers in accordance with the invention provide recyclability, enhanced container structural integrity and improved insulation. In addition, a container in accordance with the invention may be transparent. Conventional methods may be used to manufacture a thermally insulated double-walled disposable container in accordance with the invention. The manufacturing of the containers are cost effective. 9] In an aspect of the invention, a thermally insulated double-walled disposable plastic container includes a container body having an inner cup and outer cup fixedly separated by a space. The thermally insulated double-walled disposable plastic container is open at the top and enclosed at the bottom. The space includes a gas for providing thermal insulation. A preferred gas is air. Preferred methods for making the insulated double-walled disposable plastic container includes blow-molding, thermo forming or injecting molding an inner cup and outer cup then fixedly connecting the inner cup and outer cup to define an insulation space there between.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of one embodiment of a container in accordance with the invention.

FIG. 1A is an enlarged view of a wall connection in accordance with the invention.

FIG. IB is an enlarged view of an alternate wall connection in accordance with the invention.

FIG. 1C is an enlarged view of a yet another alternate wall connection in accordance with the invention. FIG. 2 is a cross-sectional view of a tapered walled container in accordance with the invention.

FIG. 2A is an enlarged view of a wall connection of a tapered walled container of the invention.

FIG. 2B is an enlarged view of alternate wall connection of a tapered walled container of the invention.

FIG. 2C is an enlarged view of a yet another alternate wall connection of a tapered walled container of the invention.

FIG. 3 is a top view of a container divided into four equal parts having two double-walled portions in accordance with the invention.

FIG. 4 is a top view of a container divided into six equal parts having three double-walled portions in accordance with the invention.

FIG. 5 is a perspective view of horizontal ribs between walls of a container of the invention

FIG. 6 is a perspective view of vertical ribs between walls of a container of the invention.

FIG. 7 is a perspective view of one embodiment of a container with both horizontal and vertical ribs between the walls.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 10] The present invention provides a thermally insulated double-walled disposable plastic container having excellent insulation properties, recyclability, and optionally transparency. As used herein the term "plastic" refers to a wide range of synthetic or semi-synthetic polymerization products, composed of organic condensation or addition polymers and may contain other substances, including bio materials and recycled content, to improve performance or reduce costs. "Disposable" as used herein is meant to describe articles that are most often discarded after one use. "Double-walled" as used herein refers to a structure that includes an inside wall, an outside wall, and a space defined between the inside wall and outside wall. The term "insulated or insulating" as used here in refers generally to the prevention of reduction of heat transfer from conducting bodies. The term "insulated double-walled disposable plastic container" may alternatively be referred to as 'container' for convenience. As used herein the terms inside wall and inside cup generally refer to the same structure and outside wall and outside cup generally refer to the same structure where the container is a cup, and respectively may be used interchangeably. 11] Referring now to FIG. 1, there is shown a container 100. In one embodiment of the invention, the container 100 is preferably a double-walled disposable plastic cup. The container 100 includes an inside wall or cup 102 and an outside wall or cup 104. The inside wall or cup 102 and the outside wall or cup 104 are fixedly separated by an insulation space 106 between them, and joined at an upper section of the container to enclose the insulation space 106. The container 100 includes an interior space 110 for containing food or beverages. The inside wall or cup 102 and the outside wall or cup 104 may be any suitable shape, but in a preferred embodiment are frusto-conical in shape with an opening at the top and a base section 108 for providing a closed end. In an embodiment of the invention, the base section 108 is also double- walled. A double-walled base section 108 preferably comprises an inwardly extending protrusion 130 that connects the inside wall or cup 102 and an outside wall or cup 104 to help provide an even distribution of gas or air in the insulation space 106. In another embodiment of the invention, the base section 108 may be single-walled (not shown). "Single-walled" as used herein refers to a structure that includes only a single layer or a structure that does not have an insulating layer. As shown, the inside wall or cup 102 and outside wall or cup 104 may be formed parallel to each other or any suitable design, including but not limited to tapered. In an embodiment of the invention, vertical ribs are welded on the inside wall or cup 102 and the outside wall or cup 104 for additional strength.

[0012] The inside wall or cup 102, the outside wall or cup 104 and the base section 108 may be formed of any suitable plastic. Preferred plastics include polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), polystyrene (PS) or combinations thereof. It is also preferred that the plastic be food grade plastic.

[0013] Insulation space 106 preferably comprises a gas. Any suitable gas may be used. It is preferred that such gas provides insulation properties equal to or better than air. Preferred gases include air, nitrogen, and hydrocarbon gases such as pentane or combinations thereof.

[0014] In accordance with an embodiment of the invention, preferably, the outside wall or cup 104 is preferably of from about 0.005 to 0.030 inches in thickness and more preferably of from about 0.010 to 0.020 inches in thickness; and the inside wall or cup 102 is preferably of from about of 0.001 to 0.012 inches in thickness and more preferably about 0.005 to 0.010. The space 106 between the inside wall 102 and the outside wall 104 is preferably between 0.025 and 0.250 inches, more preferably, between 0.100 and 0.200 inches and even more preferably, between 0.130 and 0.150 inches.

[0015] In one embodiment of the invention, the container 100 is transparent.

In this embodiment it is preferred that at least the inside wall or cup 102 and the outside wal l or cup 104 are transparent. The inside wall or cup 102 and the outside wal l or cup 104 are preferably formed from any suitable food grade plastic having transparent properties and a transparency value of 80 to 100%. While it is to be understood that the base section 108 also may be transparent, it is not required by the invention.

[0016] In one embodiment of the invention, the container 100 is translucent.

In this embodiment it is preferred that at least the inside wall 102 and the outside wal l 104 are translucent. The inside wall 102 and the outside wal l 104 are preferably formed from any suitable food grade plastics having translucent properties. While it is to be understood that the base section 108 also may be translucent, it is not required by the invention. The container may be any suitable color and it is also envisioned that the container may be opaque. [0017] The container 100 may be of any suitable size. In an embodiment of the invention, the container 100 can also be of the size and shape of a commonly used take-out container to store food or beverages. The take-out container may be of any shape, without limitation, such as a box-type container. In an embodiment of the invention, the container can be put in a microwave or freezer. In various embodiments, the container may have a length larger than the height. In a preferred embodiment of the invention, the base preferably is double-walled.

[0018] In an embodiment, wherein the container 100 is a cup, the cup may be of any suitable size. For example, the cup can be made in sizes generally used in restaurants and coffee shops, including but not limited to 12, 16, 20, 21, 22, 32 and 44oz cups.

[0019] The inside wall or cup 102 and outside wall or cup 104 may be joined or connected by any suitable techniques. A person skilled in the art would appreciate that various chemical or mechanical techniques may be used to join inside wall or cup 102 and outside wall or cup 104 such as, without limitation, welding, ultrasonic welding, adhesive sealants, rim rolling or snap fitting sealing engagement. FIG. 1A is an enlarged view of a preferred wall connection 113 by welding or using an adhesive sealant. FIG. IB is an enlarged view of a preferred wall connection, wherein the inside wall or cup 102 and outside wall or cup 104 both have an overhang rim that are rolled together by a conventional rim rolling process to form a curled overturned rim 112. The upper rim or periphery 114 of the inside wall or cup 102 is curled over the curl of the outside wall or cup 104. Such double curling also enhances the rigidity of the container 100. 0] FIG. 1C is an enlarged view of yet another preferred wall connection technique for a substantially parallel walled container 100, whereby a snap fitting sealing engagement forms a wall sealing engagement 113' that fixedly attaches the outside wall 104 and inside wall 102. The snap fitting sealing engagement is advantageous particularly in the case where a lid 120 may be used in connection with the container 100. In a preferred embodiment, the outside wall 104 is preferably provided with at least two locking protrusions 116 and 118 for engaging the inside wall 102 and a lid 120, respectively. Preferably, a first outside wall locking protrusion 116 slopes inwardly and downwardly from a top section of the outside wall 104 to provide an engagement section for the inside wall 102. The inside wall 102 is substantially parallel to the outside wall and extends above and over the top of the outside wall 104, further extending downwardly to engage an inside wall locking protrusion 116 of the outside wall 104 via an inside wall inner protrusion 117 that slopes inwardly and downwardly to engage and seal with the first outside wall locking protrusion 116. A second outside wall locking protrusion 118 slopes outwardly and downwardly below the first outside wall protrusion 116 to provide an engagement section for the lid 120. The lid 120 preferably extends below the first outside wall locking protrusion 116 and has a lid locking protrusion 119 that slopes inwardly to engage the second outside wall locking protrusion 118 and seal the lid to the cup. [0021] In another embodiment of the invention, shown in FIG. 2, the top section of the outside wall or cup 204 and the inside wall or cup 202 have a difference in taper. Any suitable angle may be used for the taper. As with the previous embodiment, the inside wall or cup 202 and outside wall or cup 204 may be connected by any suitable techniques. In a double-walled base embodiment, there is provided a centering ring 230 that connects the walls or the container to create a concentric gas gap and even distribution of gas between the outside wall or cup 204 and the inside wall or cup 202. [0022] FIG. 2A is an enlarged view of a cut-out section of a preferred wall or cup connection 213 formed by welding or gluing. The outside wall or cup 204 of the inside wall or cup 202 is sealed via an adhesive or welded in any suitable section of the container from the upper end of the taper to an outwardly extending lip or bend of the outside wall 204. The upper rim or periphery 214 of the inside wall or cup 202 is preferably formed over and welded to the lip or bend 212 of the outside wall or cup 204.

[0023] FIG. 2B is an enlarged view of a preferred tapered walled connection, where at a suitable point after the taper whereby the inside wall or cup 202 and outside wall or cup 204 meet, the overhang from both the inside wall or cup

202 and outside wall or cup 204 are rolled together by a conventional rim rolling process to form a curled overturned rim 212.

[0024] FIG. 2C is an enlarged view of yet another preferred wall connection technique for a tapered wall container 200, whereby a snap fitting sealing engagement forms a wall sealing engagement 213' that fixedly attaches the outside wall or cup 204 and inside wall or cup 202. The snap fitting sealing engagement is advantageous particularly in the case where a lid 220 may be used in connection with the container 200. In a preferred embodiment, the outside wall or cup 204 is preferably provided with at least two locking protrusions 216 and 218 for engaging the inside wall or cup 202 and a lid 220, respectively. Preferably, a first outside wall locking protrusion section 216 having an interior surface that slopes inwardly and downwardly from a top section of the outside wall or cup 204 to provide a clasp section for the inside wall 202 having a contact point 221 for a flat outer surface of the inside wall or cup 202 and an inside wall inner protrusion 217 to pinch the first outside wall locking protrusion section 216. The inside wall or cup 202 tapers toward the outside wall or cup 204 at any suitable position below the first outside wall locking protrusion section and extends above and over the top of the outside wall or cup 204, further extending downwardly to engage an flat outer surface of the first outside wall locking protrusion section 216 via the inside wall inner protrusion 217 that slopes inwardly and downwardly to pinch the first outside wall locking protrusion section 216. A second outside wall locking protrusion 218 slopes outwardly and downwardly below the first outside wall protrusion section 216 to provide an engagement section for the lid 220. The lid 220 preferably extends below the first outside wall locking protrusion section 216 and has a lid locking protrusion 219 that slopes inwardly to engage the second outside wall locking protrusion 218 and seal the lid 220 to the container. [0025] In various embodiments of the invention, the double wall is provided only to a portion of the container. The container may be divided into double- walled and single-walled portions. For example, the container may be divided into four parts out of which two are double-walled. FIG. 3 is a top view of the container 300 in an embodiment of the invention. The circumference of container 300 is divided into four equal parts having two double-walled portions. In a preferred embodiment, two alternate parts 302a, and 302b are double-walled while the other two 304a and 304b are single walled. FIG. 4 is a top view of the container 400 in an embodiment of the invention. The circumference of container 400 is divided into six equal parts having three double-walled portions. In a preferred embodiment, three alternate parts 402a, 402b, and 402c are double-walled while the other three 404a, 404b, and 404c, are single walled.

[0026] In an embodiment of the invention shown in FIG. 5, the container 500 has horizontal ribs 506 between the inside wall or cup 502 and the outside wall or cup 504. The horizontal ribs 506 are circular in shape and divide the annular region between the inside wall or cup 502 and the outside wall or cup 504 into number of horizontal sub-regions. The horizontal ribs 506 reduce convection heat loss by blocking air circulation between sub-regions. As a result, the horizontal ribs 506 enhance the thermal insulation performance of the container 500. In an embodiment of the invention, the horizontal ribs 506 are preferably about 8 mm apart. The horizontal rib thickness is preferably between about 0.001 inch and about 0.010 inch. [0027] In another embodiment shown in FIG. 6, the container 600 has vertical ribs 606 between the inside wall or cup 602 and the outside wall or cup 604. The vertical ribs 606 are rectangular in shape and divide the annular region between the inside wall or cup 602 and the outside wall or cup 604 into number of vertical sub-regions. The vertical ribs 606 reduce convection heat loss by blocking air circulation between sub-regions. As a result, the vertical ribs 606 enhance thermal insulation performance of the container 600. In an embodiment of the invention, the vertical ribs 606 are preferably about 8 mm apart. The vertical rib thickness is preferably between about 0.001 inch and about 0.010 inch.

[0028] In yet another embodiment shown in FIG. 7, the container 700 has both horizontal ribs 706 and vertical ribs 708 that form grids between the inside wall or cup 702 and the outside wall or cup 704. The grids are preferably square or rectangular. The horizontal ribs 706 and the vertical ribs 708 reduce convection heat loss by blocking air circulation between grids. As a result, the horizontal ribs 706 and the vertical ribs 708 enhance thermal insulation performance of the container 700. In an embodiment of the invention, the grids are of square shape and are preferably about 8mm by 8mm. The thickness of the grids is preferably between about 0.001 inch and about 0.010 inch.

[0029] A double-walled disposable plastic container in accordance with the invention may be formed by any suitable means. In accordance with another embodiment of the invention the container may be manufactured by conventional blow molding and trimming techniques. Generally a bottle is first formed by a conventional blow molding process. Then the top portion and the body of the bottle are separated into two pieces by a trimming process. The resultant body portion forms a cup. Any thermoplastic polymer can be used to prepare the perform, for example, polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), polystyrene (PS) or combinations thereof. It is also preferred that the plastic be food grade plastic. Preferred products are polypropylene (PP), polyethylene terephthalate (PET). In yet another embodiment of the invention, the inside and outside walls or cups are formed by a thermoforming process. 0] Injection molding is also a process that may be used to form a container in accordance with the invention. For example, both the inner wall or cup and the outer wall or cup may be formed by injection molding the walls or cups and then joining the walls or cups together by the means described above. The inner wall or cup and outer wall or cup may also be made separately on different molding machines or made on the same machine at different locations. It should also be understood that one or more of the wall forming processes described herein may be used alone or in combination. For example, in accordance with one embodiment of the invention, the outside wall or cup may be injection molded to provide rigidity having a thickness in the range of about 0.005 inch to about 0.020 inch and the inside wall or cup may be blown and trimmed to have a thickness preferably in the range of about 0.001 inch to about 0.010 inch. 1] It should be apparent that the foregoing relates only to the preferred embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general sprit and scope of the invention as defined by the following claims and equivalents thereof.

Claims

CLAIMS What is claimed:

1. A thermally insulated disposable plastic container, comprising:

i. a plastic outside wall having a thickness of about 0.005 to about 0.030 inches;

ii. a plastic inside wall having a thickness of about 0.001 to about 0.012 inches

iii. an insulation layer sandwiched between said plastic outside wall and said plastic inside wall; and

iv. a plastic base closure connected to a bottom portion of said plastic outside wall and said plastic inside wall, whereby said plastic outside wall and said plastic inside wall cooperate to define a an insulation layer having a thickness of about 0.025 to about 0.250 inches there between for providing thermal insulation for any material disposed within said container and wherein said insulation layer comprises a gas.

2. The container of claim 1, wherein said gas comprises air, nitrogen, pentane, hydrocarbon gas or combinations thereof.

3. The container of claim 1, wherein at least said plastic outside wall and said plastic inside wall have a transparency value of from about 80 to

100%.

4. The container of claim 1, wherein at least said plastic outside wall and said plastic inside wall are translucent.

5. The container of claim 1, wherein said plastic outside wall and said plastic inside wall are attached by a process comprising welding, ultrasonic welding, chemical adhesives, rim rolling, snap fit sealing or a combination thereof.

6. The container of claim 1, further comprising one or more circular horizontal ribs, rectangular vertical ribs or a combination thereof formed between the said plastic inside wall and said plastic outside wall.

7. The container of claim 1, wherein said plastic base closure is double-walled and is defined by said plastic inside wall and said plastic outside wall.

8. A double-walled disposable cup comprising an outer cup and an inner cup formed of a polymer based material, said inner cup and said outer cup coming together near or at an upper rim of said cup to form an annular space there between, wherein said inner cup has a wall thickness of from about 0.001 to about 0.012 inches, said outer cup has a wall thickness of about 0.005 to about 0.030 inches and said annular space is about 0.025 to about 0.250 inches wide.

9. The double-walled cup of claim 8 wherein at least one of said inner cup or said outer cup is tapered toward the other in a section of the cup below where said inner cup and said outer cup come together.

10. The double-walled cup of claim 8 wherein said inner cup and said outer cup are substantially parallel before coming together near said upper rim of said cup.

11. The double-walled cup of claim 8 wherein said inner cup and said outer cup form said rim of said cup.

12. The double-walled cup of claim 11 wherein the inner cup and outer cup both have an overhang rim that are rolled together to form a unitary curled rim for said cup.

13. The double-walled cup of claim 8 wherein an upper section of said outside cup near said rim comprises at least one locking protrusion for engaging an upper section of said inside cup near said rim, whereby said at least one locking protrusion slopes inwardly and downwardly of said upper section of said outside cup to provide an engagement section for said inner cup; and wherein a section of said inner cup is formed to extend above and over the top of the outer cup and further extending downwardly to engage said at least one locking protrusion of the outer cup via an inner protrusion of said inner cup that slopes inwardly and downwardly to engage and seal with the at least one locking protrusion.

14. The double-walled cup of claim 13, wherein an upper section of said outside cup near said rim further comprises a second locking protrusions for engaging a lid.

15. The double-walled cup of claim 8 wherein both said inner cup and said outer cup are transparent or translucent.

16. The double-walled cup of claim 8, wherein said polymer based material comprises polypropylene, polyethylene terephthalate, polylactic acid, polystyrene or a combination thereof.

17. The double-walled cup of claim 8, wherein said annular space is divided into at least four equal parts having at least two double-walled portions.

18. The double-walled cup of claim 17, wherein said at least four equal parts alternate between double-walled and single walled sections.

19. A method of forming a double-walled disposable plastic cup comprising the steps of:

i. forming an outer cup having a wall thickness of about 0.005 to about 0.030 inches

ii. forming an inner cup having a wall thickness of from about 0.001 to about 0.012 inches

iii. fixedly attaching said inner cup and said outer cup together near or at an upper rim of said cup and forming a space comprising a gas between said inner cup and said outer cup, wherein said space is about 0.025 to about 0.250 inches thick.

20. The method of clam 19, wherein said step of forming said outer cup comprises blow molding an outer bottle from a thermoplastic polymer and trimming said outer bottle to form said outer cup; or said step of forming said inner cup comprises blow molding an inner bottle from a thermoplastic polymer and trimming said inner bottle to form said inner cup.

21. The method of claim 19, wherein said step of fixedly attaching said inner cup and said outer cup comprises welding, ultrasonic welding, chemical adhesion, rim rolling, snap fit sealing or a combination thereof.

22. The method of claim 19, wherein at least said step of forming said outer cup or forming said inner cup comprises thermoforming.

23. The method of claim 20, wherein at least one of said step of forming said outer cup or forming said inner cup comprises injection molding and wherein at least one of said step of forming said outer cup or forming said inner cup comprises a blow molding process.