GB2368074A

GB2368074A - Corrugated board

Info

Publication number: GB2368074A
Application number: GB0123697A
Authority: GB
Inventors: Bevis Redford; Robert Woolass
Original assignee: Linpac Containers Ltd
Current assignee: DS Smith Packaging Ltd
Priority date: 2000-10-10
Filing date: 2001-10-02
Publication date: 2002-04-24
Anticipated expiration: 2021-10-02
Also published as: GB0123697D0; GB2368074B; GB0024792D0

Abstract

The corrugated board, particularly for use packaging for transit and display etc., comprises a two-ply laminate 1 of boards with each board 2,3 comprising a different flute type. Preferably the first board 3 comprises an E flute and the second board 2 comprises a laminate of two papers that are corrugated so that they have an equivalent caliper to a C flute (i.e. an M flute). The first and second corrugated boards are ideally separated by middle sheet 4 and have outer surfaces 5,6 provided to finish the board. Also disclosed is a method for forming the corrugated board.

Description

CORRUGATED BOARD DESCRIPTION This invention relates to board which may be used for, inter alia, packaging purposes and which is usually termed"corrugated board".

It is well known that items are often packaged for transit or display in boxes which are fabricated from corrugated board. Such boxes have the advantages of being fairly light, due to their being made essentially from various grades of paper, and of being fairly resilient to damage. Moreover, they provide an effective packaging medium due to the nature of the corrugated board.

Corrugated board is fabricated from a flute of paper sandwiched between two sheets. The flute is usually of sinusoidal form with the sheets being bonded thereto at the respective peaks and troughs of the flute. Such a construction provides a board which is ideal for packaging purposes as it provides protection for the items packaged therein, due to the nature of the sheet material, whilst also being resilient due to the compressibility of the flute. Indeed, corrugated board is much stronger and better suited for packaging purposes in a number of situations than other rigid paper board or cardboard.

Various types of corrugated board are known.

These are usually identified by terms which describe the size of the flute. Indeed, it is well known in the art to provide many different sizes of flutes for particular purposes. Moreover, the size of a particular type of flute will vary according to the weight of the paper used to construct it. Thus, socalled"E flutes"have a typical amplitude or caliper of 1. 1 to 1.5 mm, the amplitude varying as a function of the weight of paper used.

However, for a variety of purposes, much stronger corrugated board is required than that formed from a simple laminate of flute and outer sheets. Various modifications to the simple corrugated formula have been proposed, some of which involve providing a further flute and outer sheet to provide a'two-ply'corrugated board comprising three sheets with two flutes or, for

example, three-ply'corrugated board comprising four sheets with three flutes, whilst other modifications involve providing a laminate flute structure in between two sheets to increase the strength thereof.

It is known in the prior art, as stated above, to provide two-ply or three-ply corrugated board. In some instances three-ply corrugated board has been fabricated from three sheets of so-called"A flutes" and four sheets. However, each A flute has a caliper

in the region of 4. 0 to 4. 5, depending upon the weight of paper used. Therefore, corrugated board fabricated from three A flutes has a thickness of approximately 12. 0 to 15. 0 mm and consequently is very bulky to both store and transport.

A further proposed three ply corrugated board comprises a C flute, which has a caliper of 3. 5 to 4. 0 mm, laminated to two A flutes, providing a composite corrugated board which has a thickness of approximately 11. 5 to 13. 0 mm. This board, whilst being marginally stronger than the three A flute corrugated board, makes little saving thereover with respect to volume. Indeed, marginal costs for such packaging materials are closely associated with the cost of transport and storage thereof. Large, bulky packaging materials can take up a lot of room at a storage facility and upon transport means, such as pallets, containers and so on.

Accordingly, it is an object of the present invention to provide corrugated board which is at least as strong as conventional corrugated boards but which is lighter and thinner so as to reduce the space needed for storage and transport. It is a further object of the invention to provide a high strength corrugated board which is suitable for use in freezer applications or in moist environments.

According to a first aspect of the invention there is provided corrugated board comprising a two

ply laminate of boards, each board comprising a different flute type.

The first board may comprise an E flute and the second board may comprise a laminate of two papers.

Preferably, the laminate of two papers is corrugated such that it exhibits an equivalent caliper to a C flute.

A second aspect of the invention relates to a method of manufacturing corrugated board comprising laminating two flute papers to one another and forming a first flute therefrom, sandwiching the first flute between two sheets to form a board, forming a further flute, laminating the further flute to the board, and laminating a further sheet to the exposed further flute.

The first flute may describe a caliper equivalent to that of a C flute, each flute paper comprising C flute material, and the further flute may comprise an E flute.

Preferably the total thickness of the corrugated board does not exceed 6 mm.

The lamination may be effected utilising a PVA adhesive.

In order that the invention may be more fully understood an embodiment thereof will be now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a section through a prior art corrugated board; and Figure 2 shows a section through corrugated board according to the present invention.

Referring firstly to Figure 1, there is shown prior art corrugated board 100 comprising a threeply laminate structure of three flutes 101 and four sheets 102. Each flute 101 is an A flute which provides the corrugated board 100 with a thickness of about 15 mm.

Referring now to Figure 2, there is shown, generally indicated at 1, corrugated board according to the present invention and comprising a two-ply structure of a first flute 2 and a second flute 3, separated by a sheet 4, the board further comprising upper and lower sheets 5,6 respectively which provide outer surfaces to the finished corrugated board 1.

The first flute 2 is a so-called"M flute"and the second flute 3 is an E flute providing a nominal sheet thickness of 4.6 to 6.0 mm depending upon the weight of the paper used. Obviously, the corrugated

board 1 is much thinner than the prior art corrugated board 100. Indeed, the inventive corrugated board is approximately 60% thinner than the prior art corrugated board, whilst demonstrating the same strength in tests known in the art, such as the Edge Crush Test (ECT) and Burst Test.

In order to fabricate the corrugated board 1, two C flute papers are laminated together and then a flute of equivalent caliper to a C flute is formed, thereby providing the M flute 2. Two sheets 4,6 are laminated thereto to form an M flute board. An E flute 3 is then laminated thereto and an outer sheet 5 is laminated to the exposed E flute profile.

As the corrugated board 1 is 60% thinner than conventional high strength corrugated boards 100, 60% more can be transported on or in a conventional transport medium than is the case for conventional corrugated boards 100. For example, it is possible to fit 60% more of the inventive corrugated board 1 on to a single pallet than conventional corrugated boards 100. This, therefore, decreases the marginal costs associated with transport and storage of the corrugated board 1 over those experienced with conventional corrugated boards 100.

Furthermore, because the inventive corrugated board 1 defines a smaller volume and because there is has less air per unit volume than conventional corrugated boards 100, it is less susceptible to

damage following wetting thereof. For example, in many applications corrugated board is used in freezer storage. When corrugated board is removed from such storage, frozen water which has adhered thereto melts and soaks into the board, thus weakening it. The inventive corrugated board 1, due the greater amount of board per unit volume is less susceptible to such damage.

The relatively large proportion of board to air ratio of the inventive corrugated board 1 also increases its insulation and soundproofing performance with respect to conventional corrugated boards 100.

Claims

CLAIMS 1. Corrugated board comprising a two-ply laminate of boards, each board comprising a different flute type.
2. Corrugated board according to claim 1, wherein the first board comprises an E flute.
3. Corrugated board according to claim 1 or 2, wherein the second board comprises a laminate of two papers.
4. Corrugated board according to claim 3, wherein the laminate of two papers is corrugated, such that it exhibits an equivalent caliper to a C flute.
5. Corrugated board according any preceding claim, wherein the thickness of the board does not exceed 6 mm.
6. Corrugated board according to claim 1, substantially as hereinbefore described with reference to the accompanying drawings.
7. A method of manufacturing corrugated board comprising laminating two flute papers to one another and forming a first flute therefrom, sandwiching the first flute between two sheets to form a board, forming a further flute, laminating

the further flute to the board, and laminating a further sheet to the exposed further flute.
8. A method according to claim 7, wherein the first flute describes a caliper equivalent to that of a C flute, with each flute paper comprising C flute material.
9. A method according to claim 7 or 8, wherein the further flute comprises an E flute.
10. A method according to claim 7,8 or 9, wherein the lamination is effected utilising a PVA adhesive.
11. A method according to any of claims 7 to 10, wherein the total thickness of the corrugated board does not exceed 6 mm.
12. A method of manufacturing corrugated board according to claim 7, substantially as hereinbefore described.