Packaging materials and processes for producing packaging materials

Abstract

 The disclosure relates to a process for producing twin or multiply corrugated medium in which a first ply (2) is provided from a feeder reel (1) and is fed to a compact and lightweight spray station (3) where adhesive is sprayed onto one surface of the ply. A second ply (4) is supplied from a second feeder reel (5) and one surface of the second ply is brought into contact with the sprayed surface of the first ply and is bonded thereto. The resulting double ply is corrugated in a corrugator (6). The adhesive used is required to set during the corrugation process which can readily be arranged because the compact and lightweight spray station can be positioned immediately adjacent the corrugates.

Description

[0001] This invention relates to packaging materials and/or to a process for producing packaging materials. In particular, the invention relates to a process for producing corrugated medium for corrugated board and/or for producing corrugated board.

[0002] Corrugated board is presently utilised extensively for the manufacture of containers or boxes suitable for holding horticultural produce, household appliances, dairy products, meat, poultry and beverages. Conventional corrugated board is built up from units consisting of a corrugated medium and two liner boards positioned against this. Several of these units may need to be adhered together in order to confer strength characteristics on the resultant board. Thus the end product is bulky. Contamination by moisture through high humidity can also adversely affect sructural characteristics of corrugated board.

[0003] Therefore, it is desirable to manufacture a corrugated board of improved strength yet having a narrow cross section. In order to meet these requirements, GB-A-2,101,039 describes a process of manufacturing corrugated board wherein the corrugated medium is twin ply and the medium is adhered together using a water soluble adhesive. The resultant board is of improved rigidity, has a greater puncture resistance and is less susceptable to breakdown as a result of moisture contamination. However, one disadvantage of the Kyokuto method is that it involves roller application of the adhesive. This application is not as clean and the adhesive may not be distributed evenly over the ply, depending on the surface characteristics of the medium.

[0004] Further, the roller applicator is a bulky apparatus and this is disadvantageous as it must form part of the overall corrugating apparatus and should desirably be as compact as possible. In the formation of corrugated medium from two plys it is desirable for the bond to be effected as close as possible to the corrugated process. The reason for this is that the respective mediums can still slide slightly whilst the flute profile is being formed, but will set upon corrugation.

[0005] As a further point, the roller apparatus does not allow for flexibility with regard to the width of board to which the adhesive is applied and the apparatus is fairly difficult to clean.

[0006] Roller application of adhesive is more likely to cause flute fracture under high loadings as the paper is required to pass through nip rows causing paper drag.

[0007] It is an object of the invention to provide a process for producing corrugated medium and/or for producing corrugated board which will go at least some way to overcoming the foregoing disadvantages in a simple yet effective manner or which will at least provide the public with a useful choice.

[0008] Accordingly, in one aspect, the invention consists in a process for producing twin or multi ply corrugated medium, said process being characterised by a step wherein adhesive is spray applied onto one of said plys, said two or more plys then being brought together so as to be bonded by said adhesive.

[0009] In a further aspect the invention consists in a process for producing corrugated board, comprising the steps of;

[0010] feeding a first medium ply to a spray station;

[0011] spray applying an adhesive onto one surface of said first medium ply;

[0012] contacting the sprayed surface with one surface of a second medium ply so that the two plys bond together;

[0013] corrugating the resulting double plys;

[0014] bonding the corrugated double ply medium between first and second liner boards.

[0015] To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

[0016] One presently preferred form of the invention will now be described with reference to the accompanying drawings, wherein:

Figure 1 shows cross sectional elevation of the corrugated board produced by the process.

Figure 2 shows part of a corrugated board machine for use in producing corrugated board in accordance with the process of the invention;

Figure 3 shows a more detailed perspective view of a spray station for use in producing corrugated board in accordance with the process of the invention.

[0017] Referring now to the figures, a process is provided for producing corrugated medium for corrugated board, wherein the corrugated medium comprises at least two plys, the process being characterised by a step wherein adhesive is spray applied onto one of the plys, the two plys then being brought together so as to be bonded by the adhesive.

[0018] Although a presently preferred embodiment is herein described comprising only two plys, it will be apparent to those skilled in the art that a multi-ply medium having more than two plys could also be produced by the described process, and is envisaged within the scope of the invention.

[0019] Figure 1 shows the board produced by the process. The board has a corrugated medium 15. This is twin or multi-ply. The corrugated medium 15 is provided between two liner boards 16 and 17. In the preferred embodiment, the two plys are adhered at 18 by a strong adhesive such as polyvinyl acetate. On the other hand, the corrugated medium 15 and the liner boards 16 and 17 need only be attached at 19 by a comparatively weak bonding adhesive such as starch adhesive.

[0020] By way of example, as illustrated in Figure 2, a first ply 2 suitable for forming a medium 15 in a corrugated board may be provided on feeder reel 1. The first ply 2, is fed to a spray station 3 which is shown in more detail in figure 2. Two parallel idle rollers 7 and 8 may be provided as shown in Figure 2 under which the first ply 2 can be drawn.

[0021] The spray station spray-applies an adhesive at location 9 for example. The adhesive preferably comprises an advanced polyvinyl acetate emulsion, or may comprise any other suitable adhesive as may be determined by one skilled in the art, onto one surface of the first medium 2.

[0022] The adhesive should be selected to provide optimum stacking strength and water proofing characteristics, and preferably comprises a polyvinyl acetate adhesive with special additives. A suitable adhesive is the ENDURO synthetic adhesive supplied by National Starch and Chemical (NZ) Limited or their international affiliates.

[0023] A second medium ply 4 is supplied from a second feeder reel 5. One surface of the second medium ply 4 is brought into contact with the sprayed surface of the first medium ply 2, so that the two plys are bonded together by the spray applied adhesive.

[0024] The resulting double ply is then corrugated by known means in corrugator 6 using male and female fluted rollers for example. It is desirable to ensure that the adhesive sets instantaneously during the corrugation process rather than prior thereto for reasons obvious to those skilled in the art. Due to the light weight and compact construction of the spray station 3 this requirement can be readily met by the foregoing apparatus as the spray station 3 can be positioned immediately adjacent the corrugator. The apparatus may, for example have width dimensions between substantially 1 and 1.5 metres as illustrated in A - B in the figures. In the preferred embodiment, the spray station 3 can, for example, be positioned between substantially 1 and 2 metres from the corrugator 6.

[0025] With reference to figure 3, a suitable spray station 3 for use in the process according to the invention may include twin pumps and liquid reservoirs 10, liquid regulators 11, and an air reservoir 12. These may all supply a pressure articulation feed system to a plurality of fine atomising fan spray heads 13 such as those produced under the trade mark DEVILBISS. A control panel 14 may be provided to regulate and monitor the process.

[0026] An extractor air system 15 may be provided. This is desirable as overspray is produced by the process which should be collected and removed for environmental reasons. A suitable extractor air system 15 could be connected to a sluicing system wherein the extracted adhesive overspray enters the sluicing apparatus under vacuum for example and is contacted with water. The resulting sluice can be disposed of in due course.

[0027] The liquid pumps 10 will be selected according to the requirements of the operator, but by way of example, the liquid pumps 10 may provide a 60 litre per minute supply of adhesive.

[0028] In the embodiment of Figure 3, eight spray heads 13 are depicted. If different widths of corrugated board are to be produced, the number of operational spray heads 13 can be readily adjusted accordingly via the control panel 14 for example. For example, only the central spray heads may be operational when the width of corrugated boards being produced by the process is decreased.

[0029] In order to clean the spray apparatus suitable liquid cleaning agents can be provided in the liquid reservoirs 10 and the spray system set into action in order to circulate the cleaning agents.

[0030] In the final stages of the process, the liner boards 16 and 17 are adhered to the corrugated medium 15. Starch adhesive may be streaked on the outwardly facing surfaces of the crests and troughs 19 of the corrugations. The liner boards 16 and 17 may then be bought into contact with the corrugated medium 15 using known techniques.

[0031] Thus it can be seen that a process for producing a multi-ply corrugated medium is provided by the invention, which is principally characterised by spray application of the adhesive. By comparison with roller application, this is very efficient allowing high machine speeds, up to for example 130 metres per minute in trials. The further advantages include reduced wastage of adhesives, reduced drag, and a higher degree of control of application or coating weights of the adhesive.

[0032] The apparatus is light weight and compact and can be positioned immediately adjacent a corrugator such that corrugation can be carried out efficiently after the adhesive has been applied. The spray applicators apply the adhesive to the ply more evenly than roller application and this is desirable as any inconsistencies in the adhesive layer reduce the strengh of the resultant medium. The spray station is one which can easily be cleaned. Further, as a series of spray heads are provided the number of operational spray heads can be adjusted according to the width of the medium being produced.

[0033] This process is advantageous in providing a double or multi ply corrugated medium for corrugated board, which has enhanced properties of stacking strength, impact resistance, and efficient use of space in packing.

Claims

1. A process for producing twin or multi ply corrugated medium, said process being characterised by a step wherein adhesive is spray applied onto one of said plys, two plys then being brought together so as to be bonded by said adhesive.

2. A process as claimed in Claim 1 wherein said adhesive is applied to said medium prior to being corrugated and said plys bond together during the corrugating process.

3. A process as claimed in Claim 1 or Claim 2 wherein said adhesive comprises an advanced poly vinyl acetate emulsion or other suitable waterproof poly vinyl acetate adhesive.

4. A process as claimed in any one of Claim 1 to Claim 3 wherein the product thereof is bonded between a first and second liner board.

5. A process for producing corrugated board, comprising the steps of;

feeding a first medium ply to a spray station;

spray applying an adhesive onto one surface of said first medium ply;

contacting the sprayed surface with one surface of a second medium ply so that the two plys bond together;

corrugating the resulting double ply;

and bonding the corrugated double ply medium between first and second liner boards.

6. A process as claimed in Claim 5 wherein said adhesive comprises an advanced poly vinyl acetate emulsion or other suitable waterproof poly vinyl acetate adhesive.

7. Twin or multiply corrugated medium when manufactured by the process claimed in any one or more of Claim 1 to Claim 3.

8. Corrugated board when manufactured by the process of Claim 5 or Claim 6.

Drawing