AU2016238861B2

AU2016238861B2 - Corrugated Paperboard Product

Info

Publication number: AU2016238861B2
Application number: AU2016238861A
Authority: AU
Inventors: George Ganzenmuller
Original assignee: Opal Packaging Australia Pty Ltd
Current assignee: Opal Packaging Australia Pty Ltd
Priority date: 2011-05-17
Filing date: 2016-10-05
Publication date: 2018-11-15
Anticipated expiration: 2032-05-16
Also published as: AU2016238861A1

Abstract

A corrugated paperboard product comprising a fluted or corrugated layer having at least one paper or paperboard liner laminated thereto, wherein the fluted or corrugated 5 layer has a thermoplastic polymer selected from a polyester or polyamide applied thereto.

Description

CORRUGATED PAPERBOARD PRODUCT

FIELD OF THE INVENTION

The present invention relates to a corrugated paperboard product.

BACKGROUND TO THE INVENTION

Corrugated paperboard products, such as corrugated cardboard, are widely used in the manufacture of boxes and containers. A typical corrugated paperboard comprises a layer of corrugated or fluted paperboard having one or more sheets of paper or paperboard liner laminated thereto. For example, single face corrugated board has a layer of corrugated or fluted paperboard and a sheet of paper or paperboard liner laminated to one side of the layer of corrugated or fluted paperboard. Double face corrugated board has a layer of corrugated or fluted paperboard and a sheet of paper or paperboard liner laminated to either side of the corrugated or fluted paperboard layer. This product is also referred to as "single wall corrugated". Single face corrugated board and double face corrugated board only have a single layer of corrugated or fluted paperboard included therein.

If additional strength is required, additional layers of corrugated or fluted paperboard may be laminated to the sheets of paper or paperboard liner. For example, a second layer of fluted or corrugated paperboard may be laminated to one of the sheets of paper or paperboard liner and a further sheet of paper or paperboard liner may be laminated over the second layer of fluted or corrugated paperboard. As this paperboard product now includes two layers of corrugated paperboard, the strength of the product is increased.

Another corrugated paperboard product having increased strength is known as "duo arch". In this product, a second corrugated or fluted paperboard layer is joined to the first corrugated or fluted paperboard layer to increase the strength of the corrugated or fluted material. One or more sheets of paper or paperboard liner are then laminated to the corrugated material.

Most corrugated paperboard products are manufactured by passing paperboard material through a corrugator machine to form the fluted or corrugated paperboard. The fluted or corrugated paperboard is then passed to a laminator where a layer of adhesive is applied between the fluted or corrugated layer and the sheet of paper that is to be laminated to the fluted or corrugated layer. This acts to join the corrugated layer and the paper sheet layers together. Starch is commonly used as the adhesive and the product is typically heated during manufacture to dry out and set the starch adhesive

In corrugated paperboard products, the corrugated or fluted paperboard layer is commonly referred to as the "medium".

Throughout this specification, the term "comprising" and its grammatical equivalents shall be taken to have an inclusive meaning unless the context of use indicates otherwise.

FIELD OF THE INVENTION

It is an object of the present invention to provide an improved corrugated paperboard product or to at least provide a commercial alternative to presently available corrugated paperboard products.

In a first aspect, the present invention provides a corrugated paperboard product comprising a fluted or corrugated layer having at least one paper or paperboard liner laminated thereto, wherein the fluted or corrugated layer has a thermoplastic polymer selected from a polyester or polyamide applied thereto.

In one embodiment, the thermoplastic polymer acts as an adhesive to join the fluted or corrugated layer to the at least one paper or paperboard liner.

In one embodiment, the corrugated paperboard product comprises a single face corrugated paperboard.

In another embodiment, the corrugated paperboard product comprises a double faced corrugated paperboard (or a single wall corrugated paperboard).

In one embodiment, the thermoplastic polymer selected from polyester or polyamide is applied directly to the corrugated or fluted layer. In another embodiment, the thermoplastic polymer is applied to a paperboard sheet prior to passing the paperboard sheet through a corrugator machine. Suitably, the thermoplastic polymer selected from polyester or polyamide is in direct contact with the material from which the corrugated or fluted layer is made. Even more suitably, no intervening layers or adhesives are required to maintain the thermoplastic polymer on the corrugated or fluted layer.

In one embodiment, the thermoplastic polymer is applied in an amount such that the corrugated paperboard product has increased strength, when compared to conventional corrugated paperboard products. In this regard, the polyester or the polyamide may be added in an amount such that the polyester or the polyamide enhances the strength of the corrugated layer. In this manner, it may be possible to manufacture a corrugated paperboard product that has strength properties that are equivalent to or even stronger than duo arch products.

The polyester or polyamide polymer may also be selected such that a desired strength at a specified loading of polymer is achieved. For example, a higher-strength polymer may be used at a lower loading, or a lower strength polymer may be used at a higher loading.

In some embodiments, the polyamide polymer may be a nylon.

In some embodiments, the polyester or polyamide polymer is applied to the corrugated paperboard prior to laminating the one or more paper or paperboard liners to the corrugated paperboard. In other embodiments, the polyester or polyamide polymer is applied to the corrugated paperboard as part of the laminating process. In this embodiment, the polyester or polyamide polymer is applied between the corrugated paperboard layer and the paper or paperboard liner, with the polyester or polyamide polymer being used to adhere the paper or paperboard liner to the corrugated paperboard layer.

In some embodiments, the polyester or polyamide polymer is applied in to the paperboard layer in the form of a molten polymer. In other embodiments, the polyester or polyamide polymer is applied to the paperboard layer as a sheet or film of polymer. This sheet or film of polymer may be heated in order to have the sheet or film of polymer adhere to the paperboard layer.

In some embodiments, the polyester or polyamide polymer may be applied to a sheet of paperboard. The combined polymer/paperboard sheet may then pass through a corrugator machine to form the corrugated layer of paperboard.

In some embodiments, the polyester or polyamide polymer is applied in a molten form and the polyester or polyamide polymer extends throughout the substantial thickness of the corrugated paperboard layer.

The present invention also encompasses methods for manufacturing the corrugated paperboard product described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a cross-sectional view of a corrugated paperboard product in accordance with one embodiment of the present invention;

Figure 2 shows a cross-sectional schematic diagram of a process for manufacturing a paperboard product in accordance with an embodiment of the present invention;

Figure 3 shows a cross-sectional schematic diagram of an alternative process for manufacturing a paperboard product in accordance with an embodiment of the present invention; and

Figure 4 shows a cross-sectional schematic diagram of a further process for manufacturing a paperboard product in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The drawings have been provided for the purposes of illustrating preferred embodiments of the present invention. Therefore, it will be understood that the present invention should not be considered to be limited solely to the features as shown in the attached drawings.

Figure 1 shows a cross-sectional diagram of a double faced corrugated paperboard. Such products are also referred to as single wall corrugated products. This product comprises a corrugated middle layer 10 made from corrugated paperboard. This corrugated layer is often referred to as the medium". A first layer of paper or paperboard liner 12 is laminated to one side of the medium 10 and a second layer 14 of paper or paperboard liner is laminated to the other side of the medium 10. In conventional products, an adhesive is typically used to adhere the layers 12, 14 to the medium 10. If a high-strength product is required, the medium 10 may comprise two layers of corrugated material that are bonded together. Such a product is commonly known as a duo arch product.

In the present invention, the medium 10 (which comprises the corrugated layer) has a thermoplastic polymer selected from a polyester or a polyamide applied to it. In this manner, the strength of the medium 10 can be controlled or adjusted. In particular, the thermoplastic polymer that is applied to the medium 10 has a certain strength at room temperature or at the temperature of use of the paperboard product. This acts to reinforce and strengthen the medium 10. As a further benefit, the thermoplastic polymer may also improve the water resistance of the medium 10.

The paperboard product shown in figure 1 may be made using a number of different techniques. One technique is shown in figure 12. In figure 12, a roll of paperboard 20 is provided. The paperboard is fed, in the form of a sheet 22, to a corrugator 24. The corrugated 24 operates in a known manner to form a corrugated sheet 26.

The first paperboard liner 12 and second paperboard liner 14 are fed from respective rolls 28, 30 of paperboard. Guide rollers 32, 34 are used to properly direct the sheets 12, 14 that are taken from the rolls 28, 30.

In the process shown in figure 2, molten thermoplastic polymer, such as molten polyamide or molten polyester, is sprayed by sprayers (as shown schematically by arrows 36 and 38) such that the molten thermoplastic material is positioned between the corrugated medium 26 and the paperboard liners 12, 14. Suitably, the molten thermoplastic polymer is sprayed on to either side of the corrugated medium 26 just prior to the corrugated medium 26 being forced into contact with the paperboard liners 12, 14 in laminator 40. In laminator 40, the paperboard liners 12, 14 are brought into contact with the corrugated medium 26, for example, by use of appropriate press rollers. As the thermoplastic polymer cools, it hardens and solidifies, which also acts to bond the paperboard liners 12, 14 to the corrugated medium 26. The final product 42 is shown leaving the corrugator 40.

In some embodiments of the process shown in figure 2, the molten thermoplastic material largely impregnates the entirety of the corrugated medium 26. In some instances, the molten thermoplastic material may also be impregnated at least partly into the paperboard liners 12, 14. This assists in providing an enhanced bond between the corrugated medium 26 and the paperboard liners 12, 14.

Figure 3 shows an alternative method for producing the paperboard product shown in figure 1. In figure 3, a roll 50 of the paperboard is unrolled in a conventional fashion such that a sheet 52 is taken off the roll 50. Molten thermoplastic material, such as molten polyester or molten polyamide, is sprayed by a sprayer, shown schematically at 54, on to the sheet 52 of paperboard. It might also be possible to provide another sprayer underneath the sheet 52 so that both sides of the sheet 52 become coated with the molten thermoplastic polymer. However, if the sheet 52 has sufficient permeability such that the molten thermoplastic polymer can impregnate all the way through the thickness of sheet 52, the second sprayer positioned underneath the sheet 52 may not be required.

Once the molten polymer 54 has been applied to the sheet 52, it is allowed to cool and hardened or solidify. The sheet 52 that now has the thermoplastic polymer applied thereto enters a corrugator 56 and a corrugated medium 58 leaves the corrugator 56. Suitably, the thermoplastic polymer that is applied to the paperboard sheet 52 is chosen such that it does not melt as it passes through the corrugator 56. Rolls 60, 62 of paperboard liner are used in conjunction with guide rollers 61, 63 to feed sheets 64, 66 of paperboard liner into a laminator 68. In the laminator 68, the thermoplastic polymer is heated such that the thermoplastic polymer either softens or melts. Press rollers are used to press the paperboard liners 64, 66 into contact with the corrugated medium 58. The softened or melted polymer may impregnate partly into the paperboard liners 64, 66. As the thermoplastic polymer cools and hardens, a sound bond is achieved between the corrugated medium 58 and the paperboard liners 64, 66. The final paperboard product 70 is shown leaving the laminator 68.

Figure 4 shows a variation of the process shown in figure 3. In figure 4, a roll 80 of paperboard has a sheet 82 of paperboard unrolled therefrom. A molten thermoplastic polymer is sprayed on to either side of the paperboard sheet 82 using sprayers that are shown schematically at 84, 86. After passing through the polymer spraying station, the molten polymer is allowed to cool and the paperboard sheet 88 that has the thermoplastic polymer applied thereto is rolled onto roll 90. The roll 90 may be sent to storage.

When it is desired to use the roll 90, it is moved to an unrolling station and a sheet 88 of paperboard having the thermoplastic polymer applied thereto is unrolled therefrom. The paperboard product 88 is then subjected to the same processing steps as shown in figure 3. For convenience, like reference numerals will be used in figure 4 to denote the same features that are shown in figure 3. These features need not be described further.

The present invention who is based upon applying a thermoplastic polymer selected from a polyamide or polyester to a paperboard product to form a functional polymer/paper laminated medium. The thermoplastic polymer is selected and applied to the paperboard medium in appropriate amounts to provide enhanced strength to the medium. Enhanced water resistance is also likely to be achieved. As a further advantage, it is not necessary to use a separate adhesive to laminate the paper liner to the medium in order to form the complete product. The thermoplastic polymer itself can act as the binder.

Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It will be understood that the present invention encompasses all such variations and modifications that the form of the spirit and scope.

Claims

1. A corrugated paperboard product comprising a fluted or corrugated layer having at least one paper or paperboard liner laminated thereto, wherein the fluted or corrugated layer has a thermoplastic polymer selected from a polyester or a polyamide applied thereto, wherein the thermoplastic polymer acts as an adhesive to join the fluted or corrugated layer to the at least one paper or paperboard liner.

2. A corrugated paperboard product as claimed in claim 1 wherein the corrugated paperboard product comprises a single face corrugated paperboard.

3. A corrugated paperboard product as claimed in claim 1 wherein the corrugated paperboard product comprises a double faced corrugated paperboard (or a single wall corrugated paperboard).

4. A corrugated paperboard product as claimed in any one of the preceding claims wherein the thermoplastic polymer selected from polyester or polyamide is applied directly to the corrugated or fluted layer, or the thermoplastic polymer is applied to a paperboard sheet prior to passing the paperboard sheet through a corrugator machine.

5. A corrugated paperboard product as claimed in claim 4 wherein the thermoplastic polymer selected from polyester or polyamide is in direct contact with the material from which the corrugated or fluted layer is made.

6. A corrugated paperboard product as claimed in claim 4 or claim 5 wherein no intervening layers or adhesives are required to maintain the thermoplastic polymer on the corrugated or fluted layer.

7. A corrugated paperboard product as claimed in any one of the preceding claims wherein the thermoplastic polymer is applied in an amount such that the corrugated paperboard product has increased strength, when compared to conventional corrugated paperboard products.

8. A corrugated paperboard product as claimed in claim 7 wherein the polyester or the polyamide is added in an amount such that the polyester or the polyamide enhances the strength of the corrugated layer to produce a corrugated paperboard product that has strength properties that are equivalent to or even stronger than duo arch products.

9. A corrugated paperboard product as claimed in any one of the preceding claims wherein the polyamide polymer comprises a nylon.

10. A corrugated paperboard product as claimed in any one of the preceding claims wherein the polyester or polyamide polymer is applied to the corrugated paperboard prior to laminating the one or more paper or paperboard liners to the corrugated paperboard.

11. A corrugated paperboard product as claimed in any one of claims 1 to 9 wherein the polyester or polyamide polymer is applied to the corrugated paperboard as part of the laminating process.

12. A corrugated paperboard product as claimed in claim 11 wherein the polyester or polyamide polymer is applied between the corrugated paperboard layer and the paper or paperboard liner, with the polyester or polyamide polymer being used to adhere the paper or paperboard liner to the corrugated paperboard layer.

13. A corrugated paperboard product as claimed in any one of the preceding claims wherein the polyester or polyamide polymer is applied in to the paperboard layer in the form of a molten polymer, or the polyester or polyamide polymer is applied to the paperboard layer as a sheet or film of polymer.

14. A corrugated paperboard product as claimed in claim 13 wherein the sheet or film of polymer is heated to cause the sheet or film of polymer adhere to the paperboard layer.

15. A corrugated paperboard product as claimed in any one of claims 1 to 12 wherein the polyester or polyamide polymer is applied to a sheet of paperboard and the combined polymer/paperboard sheet then passes through a corrugator machine to form the corrugated layer of paperboard.

16. A corrugated paperboard product as claimed in any one of claims 1 to 12 wherein the polyester or polyamide polymer is applied in a molten form and the polyester or polyamide polymer extends throughout the substantial thickness of the corrugated paperboard layer.

17. A method of manufacturing a corrugated paperboard product as claimed in claim 1 comprising applying the polyester or polyamide polymer to a sheet of paperboard and passing the combined polymer/paperboard sheet through a corrugator machine to form the corrugated layer of paperboard, and laminating at least one sheet of paper or paperboard liner to the corrugated layer of paperboard.

18. A method of manufacturing a corrugated paperboard product as claimed in claim 1 comprising applying the polyester or polyamide polymer between the corrugated paperboard layer and the paper or paperboard liner, with the polyester or polyamide polymer being used to adhere the paper or paperboard liner to the corrugated paperboard layer.

19. A method as claimed in claim 18 wherein the polyester or polyamide polymer is applied in to the paperboard layer in the form of a molten polymer, or the polyester or polyamide polymer is applied to the paperboard layer as a sheet or film of polymer.