LAYERED PROTECTIVE PACKAGING

Abstract

A method of manufacturing layered protective packaging materials and a protective packaging product is described. In an embodiment the method comprises the steps of: selecting one or more layers of a substrate; treating at least one surface of at least one of said layers with a coating composition; drying the layers to substantially remove the water content from the coating composition; and applying heat and/or radiation to the coating composition to volumetrically expand the coating composition to transform the treated layer into a protective layer. The step of treating the layer with the coating composition uses a flexographic coating technique.

Claims

1. A method of manufacturing layered protective packaging materials, said method comprising the steps of: selecting one or more layers of a substrate; treating at least one surface of at least one of said layers with a coating composition; drying the layers to substantially remove the water content from the coating composition; and applying heat and/or radiation to the coating composition to volumetrically expand the coating composition to transform the treated layer into a protective layer; whereby the step of treating the layer with the coating composition uses a flexographic coating technique.

2. The method of claim 1 wherein the flexographic coating technique further comprises a pan roller, a transfer cylinder and a plate cylinder.

3. The method of claim 2 wherein the plate cylinder comprises a plurality of transfer pads arranged in a pattern.

4. The method of claim 3 wherein the transfer pads are one or more of Velcro sponge pads or similar materials.

5. The method of claim 3 wherein the transfer pads transfer the coating composition from the transfer cylinder to one or more surfaces of one or more layers of the substrate.

6. The method of claim 1 further comprising the steps of: applying an adhesive to outer edges of one or more surfaces of the packaging substrate prior to treating a surface of a layer with the coating composition; and pressing at least one treated layer and another layer together to form a multi-substrate treated layer.

7. The method of claim 1 further comprising the step of winding said protective packaging material onto a reel for storage prior to the step of applying heat and/or radiation.

8. The method of claim 1 wherein the step of applying heat and/or radiation comprises the step of using infra-red emitters as a heat source to activate the coating composition to form the protective packaging.

9. A protective packaging product comprising: a substrate comprising one or more layers, wherein at least one surface of at least one of said layers is a treated layer comprising a coating composition; said at least one treated layer dried to substantially remove the water content from the coating composition; and said coating composition treated by heat and/or radiation to volumetrically expand the coating composition to transform the treated layer into a protective layer.

10. The protective packaging product of claim 9 wherein the one or more layers comprises two layers.

11. The protective packaging product of claim 9 wherein the substrate is paper.

12. The protective packaging product of claim 9 wherein the coating composition is microspheres.

13. The protective packaging product of claim 9 wherein the coating composition expands at least 100% after the application of the heat and/or radiation.

14. The protective packaging product of claim 9 wherein the coating composition comprises a water-based polymer prepared by emulsion polymerisation.

15. The protective packaging product of claim 14 wherein the coating composition further comprises a plurality of expandable micro spheres having an expansion temperature and optionally an additive.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] Embodiments will be described, by way of example only, with reference to the drawings, in which

[0027] FIG. 1 illustrates an exemplary embodiment of an apparatus for performing a method of one aspect of the present invention, said apparatus showing a flexographic system for applying coating composition to a layer of a substrate;

[0028] FIG. 2 illustrates an example backing sheet for mounting to the apparatus of FIG. 1 and comprising applicators for applying the coating composition;

[0029] FIG. 3 illustrates a part of the apparatus of FIG. 1, with a layer of a substrate after application of the coating composition by the applicators of FIG. 2; and

[0030] FIG. 4 shows machinery incorporating the apparatus of FIG. 1.

[0031] It should be noted that the Figures are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these Figures have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar feature in modified and different embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

[0032] FIG. 1 shows an exemplary embodiment of a system for performing a method of one aspect of the present invention, said system showing a flexographic system 100 for applying a coating composition to a layer of a substrate 140. In particular, a transfer roller or cylinder 110 is shown for collecting coating composition from a pan roller (not shown) that acts to collect coating composition. It can be appreciated that the coating composition may be directly applied to the transfer roller 110.

[0033] A plate cylinder 120 adjacent to the transfer cylinder 110 collects coating composition from the transfer cylinder 110 using a series of transfer pads arranged on a backing sheet 160 placed onto the plate cylinder 120. The use of a backing sheet allows the patterning to be easily changed compared to applying the transfer pads direct to the plate cylinder.

[0034] An impression cylinder 130 may also be used to guide and press the substrate 140 against the plate cylinder 120. The impression cylinder allows the transfer pads to transfer coating composition to the substrate in the desired pattern. The coating composition then forms a series of patterned deposits 150 on the layer of the substrate 140.

[0035] The coating composition comprises microspheres having a polymeric shell, such as polyacrylonitrile, around a hydrocarbon core. Example microspheres include those sold under the trade name DUALITE and other similar examples such as those sold under the trade name EXPANCEL.

[0036] The expandable microspheres typically have an unexpanded size, from about 10 microns to about 40 microns in diameter that increases in the presence of heat and/or radiation by about 3 times to about 10 times. Additionally, expansion typically causes changes into a foam-like material, which assists to provide the desired impact resistance and insulation.

[0037] The coating composition generally comprises a water-based polymer, such as vinyl acetate ethylene dispersion, polyvinyl acetate, polyvinyl acetate polyvinyl alcohol, dextrin stabilized polyvinyl acetate, polyvinyl acetate copolymers, vinyl acetate ethylene copolymers, vinyl acrylic, styrene acrylic, acrylic, styrene butyl rubber, polyurethane and mixtures thereof. Particularly preferred emulsion polymer components are vinyl acetate ethylene dispersion, vinyl acrylic, styrene acrylic, acrylic, and polyvinyl acetate. Typically the water-based polymer is prepared by emulsion polymerisation. Furthermore, as noted above, the coating composition may further comprise a plurality of expandable microspheres having an expansion temperature and optionally an additive.

[0038] FIG. 2 shows an example backing sheet 160 according to an embodiment of the present invention. The backing sheet is typically paper or other flexible sheet. As shown, a series of transfer pads 165 are arranged on the backing sheet 160 in an ordered pattern. In the example shown a hexagonal pattern is used. The transfer pads 165 are typically Velcro (hook and loop fastenersin this aspect the loops) and are circular in shape (approximate diameter 1.2 cm, although it can be appreciated that other diameters may be used). The primary purpose of the transfer pads is to wick coating composition from the transfer cylinder 110 and apply the coating composition to the layer of the substrate 140.

[0039] FIG. 3 shows the substrate 170 after application of the coating composition from the backing sheet 160. The coating composition forms a series of deposits 150 on the surface.

[0040] Once applied, the coated substrate is dried or cured to set the coating composition. This removes water content from the coating composition. Low intensity Infra-red is typically used to dry the coating composition, applied at a low intensity to ensure that the coating composition is not of sufficient intensity to cause expansion. It can be appreciated that heat, air or the like could be used to dry the coated substrate. Removal of at least some of the water content of the coating composition can aid in the later thermal activation and expansion of the coating composition.

[0041] After the deposition, one or more layers may be adhesively pressed against the layer 140 to form a multi-layered substrate. The adhesive is typically applied prior to application of the coating composition. The multi-layered substrate can then be stored as needed.

[0042] In order to activate and prepare the protective packaging, heat and/or radiation is applied to the coating composition (typically indirectly) to volumetrically expand the coating composition. This transforms the treated layer containing the coating composition into a protective layer. The expansion transforms the coating composition into a foam.

[0043] The coating composition may expand to between 10 and 100 times its original volume. In some embodiments the coating composition may expand at least 100% after the application of the heat and/or radiation. As an example, the composition may expand by any range between 100 and 500%, 500% and 1000% or up to 2500%. This degree of expansion transforms the treated layer into a protective layer, providing impact resistance (and thermal insulation).

[0044] Once the protective layer is formed, the multi-layered substrate can then be used as protective packaging material for use in protective padded mailers or the like. It may also be used as a packaging material in place of foam or pellets or the like.

[0045] It can be appreciated that although described above in relation to a multi-layered substrate there may be applications and embodiments that do not require a multilayer substrate. Drying and activation of the coating composition as described above may still be achieved to provide a substrate having protective packaging properties.

[0046] FIG. 4 shows a section of the machinery 300 used to carry out the method described above. In particular, for creating a multi-layered substrate. In FIG. 4 a liquid coating machine 310 and an adhesive coating machine 320 are shown.

[0047] As shown, a substrate 140 is introduced to the liquid coating machine 310 from a spool or earlier processing machine. The substrate is typically paper, or cardboard or the like, although plastics may also be used. The substrate is typically fed into the machine to present an inner surface to a series of flexographic rollers, which will be described below.

[0048] The liquid coating machine 310 comprises a transfer roller 110 that collects coating composition from a pan roller 112 that in turn collects a coating composition from a pan or similar source. As noted earlier in relation to FIGS. 1 and 3, a plate cylinder 120 having transfer pads 160 receives the adhesive from an impression cylinder 130 and transfers the adhesive to an underside of the substrate 140 as the substrate is fed through the machine. This produces a coated substrate 170 having a patterned surface 150 on an inner surface of the coated substrate 170.

[0049] At this point the coated substrate may be dried or cured to stabilise the patterned surface. As noted above, infra-red or other low intensity drying or curing processes may be used. Additionally or alternatively this step may occur after the step described below.

[0050] As shown, a second substrate or layer 240 is fed into an adhesive coating machine 320. This layer 240 has an adhesive coating applied to an outer surface in a similar manner to the process used to apply the coating composition, namely applying an adhesive coating collected by a transfer roller 210, pan roller 212, plate cylinder 220 and impression cylinder 240. It can be appreciated that the transfer pads 160 of the liquid coating machine may be replaced with alternative shaped transfer pads for the adhesive coating machine, or indeed impressions may be used on the impression cylinder 240 to apply the adhesive to the substrate 240.

[0051] The adhesive coated substrate 270 is then pressed against the coated substrate 170 to form a multi-substrate 290. The step of pressing typically involves bringing the substrates together to embody the coating composition under tension. The multisubstrate is then subject to heat and/or radiation to lower the water content of the coating composition (if not already done). Finally, as described above, the substrate is then subject to infra-red, heat or the like to transform the impressions 150 of the coating composition, causing them to expand in volume and form a padding layer between the adhesive coated substrate and the coated substrate. Such products may be used as padded mailers or the like, or for other applications that benefit from protective layered padding as described above.

[0052] From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of packaged mailers and which may be used instead of, or in addition to, features already described herein.

[0053] Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

[0054] Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

[0055] For the sake of completeness it is also stated that the term comprising does not exclude other elements or steps, the term a or an does not exclude a plurality, and reference signs in the claims shall not be construed as limiting the scope of the claims.