AU2016225909A1 - A cover suitable for covering grain - Google Patents

Description

1 2016225909 09 Sep 2016

A COVER SUITABLE FOR COVERING GRAIN

Introduction [0001] The present invention relates to a cover. The cover has been specifically designed for covering grain and will herein be generally described in this context. The cover may be utilised in temporary, semi-permanent or permanent applications.

[0002] It is to be appreciated, however, that the cover may be utilised for covering other stored agricultural and horticultural products besides grain, including other food items and hay. If desired, it may also be utilised to cover non-agricultural and non-horticultural items and products.

Background to the Invention [0003] Grain covers are widely used in agriculture and horticulture. They are manufactured in a variety of sizes and shapes.

[0004] Grain covers manufactured from flexible polyvinylchloride (PVC) have been used for many years in Australia and elsewhere. Flexible PVC grain covers are typically a combination of polyester fibres encased within a polyvinyl coating. Such grain covers are relatively robust and hard wearing, and so can often survive in harsh environmental conditions for 5 years or more prior to requiring replacement. Replacement of such covers provides a significant issue because, once end-of-life is reached, polyvinylchloride grain covers are discarded. However, municipal councils are becoming more reluctant to receive discarded covers for landfill. This is particularly so in instances where the cover is of an immense size, such that a large volume of polyvinylchloride is involved.

[0005] Alternatively, virgin polypropylene (PP) or virgin polyethylene (PE) may be utilised in the manufacture of grain covers. Polypropylene covers typically utilise polypropylene base fibres encased in a polypropylene coating. Polyethylene covers typically utilise High Density Polyethylene (HDPE) base fibres encased in a Low Density Polyethylene (LDPE) coating. These covers, too, are relatively robust and hard wearing, although they require a large amount of polypropylene or polyethylene in their manufacture and, like polyvinyl covers, usually find their way to landfill once they reach their end-of-life. <1ilename> 2 2016225909 09 Sep 2016 [0006] It would therefore be desirable to provide a more environmental solution to end-of-life grain covers ending up as landfill. It would also be desirable to provide an alternative grain cover utilising less virgin material and that is potentially more cost effective to manufacture than existing grain covers.

Summary of the Invention [0007] According to a broad aspect of the present invention, there is provided a cover suitable for covering grain. The cover includes a base layer and a coating layer applied to the base layer. The coating layer includes either recycled polypropylene or recycled polyethylene.

[0008] In one form, the coating layer includes a blend of recycled polypropylene and at least substantially virgin grade polypropylene. In another form, the coating layer includes a blend of recycled polyethylene and at least substantially virgin grade polyethylene.

[0009] In a particular embodiment of the invention contemplated by the applicant that utilises polypropylene, polypropylene is recycled from at least one end-of-life grain cover. This is particularly desirable, as existing end-of-life grain covers are not recycled, but instead generally end up as land-fill. Thus, the present invention provides a unique way of utilising end-of-life grain covers in the production of new grain covers.

[0010] In an embodiment of the invention that utilises polyethylene, polyethylene is recycled from at least one end-of-life grain cover. Polyethylene based grain covers generally have less desirable performance characteristics to polypropylene; however, can be used as an alternative to polypropylene.

[0011] In a preferred form, the coating layer is applied to a first side of the base layer and to an opposing second side of the base layer. However, versions are also contemplated in which the coating layer may be applied to only one side of the base layer.

[0012] Each of the first and second sides of the base layer preferably includes a plurality of coating sub-layers applied thereto. In one embodiment, the coating layer applied to each of the first and second sides of the base layer includes a first sub-<filename> 3 2016225909 09 Sep 2016 layer adjacent the base fabric, a second sub-layer provided over the first sub-layer, and a third sub-layer provided over the second sub-layer. In the context of a grain cover, the first side may be the top side of the cover, and the second side may be the underside of the cover.

[0013] Preferably, the percentage, by weight, of recycled polypropylene in the second sub-layer of the coating layer applied to the first side of the base layer is greater than the percentage, by weight, of recycled polypropylene in the first and third sub-layers applied to the first side of the base layer.

[0014] Further, the percentage, by weight, of recycled polypropylene in the third-sub-layer of the coating layer applied to the first side of the base layer is preferably less than the percentage, by weight, of recycled polypropylene in the first and second sub-layers applied to the first side of the base layer.

[0015] The first sub-layer provided on the first side of the base layer may include between approximately 10%, by weight, of recycled polypropylene and approximately 40%, by weight, of recycled polypropylene; the second sub-layer provided on the first side of the base layer may include between approximately 20%, by weight, of recycled polypropylene, and approximately 60%, by weight, of recycled polypropylene; and the third sub-layer provided on the first side of the base layer may include less than 20%, by weight, of recycled polypropylene.

[0016] In particular, but non-limiting, versions of the cover, the first sub-layer provided on the first side of the base layer may include approximately 12%, by weight, of recycled polypropylene; the second sub-layer provided on the first side of the base layer may include approximately 24%, by weight, of recycled polypropylene; and the third sub-layer provided on the first side of the base layer may include substantially no recycled polypropylene.

[0017] The percentage, by weight, of recycled polypropylene in the second sublayer of the coating layer applied to the second side of the base layer is preferably greater than the percentage, by weight, of recycled polypropylene in the first and third sub-layers applied to the second side of the base layer. <lilename> 4 2016225909 09 Sep 2016 [0018] Also, the percentage, by weight, of recycled polypropylene in the third-sub-layer of the coating layer applied to the second side of the base layer is preferably less than the percentage, by weight, of recycled polypropylene in the first and second sub-layers applied to the second side of the base layer.

[0019] The first sub-layer provided on the second side of the base layer may include between approximately 10% and 40%, by weight, of recycled polypropylene; the second sub-layer provided on the second side of the base layer may include between approximately 20% and 60%, by weight, of recycled polypropylene; and the third sub-layer provided on the second side of the base layer may include up to approximately 40%, by weight, of recycled polypropylene.

[0020] In particular, but non-limiting, versions of the cover, the first sub-layer provided on the second side of the base layer includes between approximately 12% and 24%, by weight, of recycled polypropylene; the second sub-layer provided on the second side of the base layer includes between approximately 24% and 38%, by weight, of recycled polypropylene; and the third sub-layer provided on the second side of the base layer includes approximately 8%, by weight, of recycled polypropylene.

[0021] It is envisaged that manufacture of the cover includes the base layer being co-extrusion coated with the coating layer. Further, it is envisaged that manufacture of the cover includes the base layer being co-extrusion coated with each sub-layer of the first and second sides of the coating layer. This is possible by utilising the applicant’s unique product and process, which combines virgin grade polypropylene pellets and recycled polypropylene pellets in the co-extrusion process to produce the applicant’s new cover.

[0022] The applicant has been able to produce a grain cover utilising recycled grain covers by virtue of providing a unique multi-layered coating on each side of the base layer, with the majority of recycled polypropylene provided in a middle layer of the multi-layered coating provided on each side of the base layer. As a result, the potential impact of the recycled polypropylene in terms of critical performance criteria such as coating adhesion, weather resistance, weldability and flex resistance is minimised. Indeed, some performance criteria are improved by the addition of <1ilename> 5 2016225909 09 Sep 2016 recycled polypropylene such as derived from end-of-life grain covers. It has been found that up to 40%, by weight, of recycled polypropylene from end-of-life grain covers may be incorporated into the applicant’s unique grain cover coating layer without compromising the performance or properties of the final grain cover.

[0023] The recycled polypropylene preferably has a melt flow index (MFI) of between approximately 10 and approximately 30; and a flexural modulus between approximately 100 Mpa and approximately 400Mpa.

[0024] The base layer may be manufactured in any suitable form. In one suitable form, the base layer includes a base fabric woven from polypropylene fibres. A particularly preferred form includes a base fabric woven from 100% polypropylene high-tenacity fibres, with a weave density of approximately 20 X 20 yarns/inch. It is highly advantageous for the base layer to also be manufactured from polypropylene, as this provides a homogenised grain cover manufactured entirely (or at least substantially entirely) from polypropylene, such that it can be recycled through a polypropylene waste stream when it reaches its end-of-life.

[0025] Various embodiments and features of the invention have been generally described above in paragraphs [0011] to [0024]. These paragraphs refer to the invention in the context of utilising polypropylene, specifically recycled polypropylene. It is to be appreciated, however, that each the various embodiments and features described in paragraphs [0011] to [0024] may instead apply to utilisation of polyethylene (specifically recycled polyethylene) rather than polypropylene. Thus, the term “polypropylene” in each of paragraphs [0011] to [0024] is to be generally understood as referring to either “polypropylene” or “polyethylene”.

Brief Description of the Drawing [0026] It will be convenient to hereinafter describe a preferred embodiment of the invention with reference to the accompanying drawing. The particularity of the drawing is to be understood as not limiting the preceding broad description of the invention. The embodiment described below pertains to a polypropylene cover, but could also apply to a polyethylene cover. <filename> 6 2016225909 09 Sep 2016 [0027] Figure 1 is a perspective sectional schematic view of a cover suitable for covering grain according to a specific, but non-limiting, form of the invention.

Detailed Description of the Drawing [0028] Referring to Figure 1, there is illustrated a cover 10 suitable for covering grain. The cover 10 may be utilised in numerous related applications, other than covering grain. For example, the cover 10 may be utilised in covering other agricultural or horticultural products, as well as other possible applications. The cover 10 may be provided in any specific size and shape, which will typically be dictated by the intended application.

[0029] The cover 10 includes a base layer 12, and a coating layer 14 applied to the base layer 12.

[0030] The base layer 12 is manufactured from 100% polypropylene high-tenacity fibres 16, having a weave density of approximately 20 X 20 yarns/inch; while the coating layer 14 is manufactured from a blend of recycled polypropylene and a virgin grade polypropylene provided in pellet-form.

[0031] The recycled polypropylene content in the illustrated embodiment is derived from end-of-life grain covers. This is a desirable re-use of such covers, which have a limited life, with end-of-life covers generally ending up as land-fill. This is considered wasteful and bad for the environment. Because of this, many municipal tips are reluctant to receive end-of-life grain covers as waste. Reusing end-of-life grain covers in the manufacture of new grain covers is considered by the applicant to be unique. It is to be appreciated, however, that the recycled polypropylene content used in the manufacture of the cover 10 need not be derived solely from end-of-life grain covers. It may be a blend of recycled polypropylene, only some of which is derived from end-of-life grain covers.

[0032] The recycled polypropylene in the illustrated embodiment preferably has a melt flow index (MFI) of between approximately 10 and approximately 30; and a flexural modulus between approximately 100 Mpa and approximately 400Mpa.

[0033] It can be seen in Figure 1 that the coating layer 14 is applied to both sides of the base layer 12. That is, the coating layer 14 is applied to a first side 18 of the <filename> 7 2016225909 09 Sep 2016 base layer 12, and to an opposing second side 20 of the base layer 12. The first side 18 corresponds to an upper or top side of the cover 10. That is, the first side 18 is the side of the cover 10 visible from above when in use; while the second side 20 corresponds to the cover’s underside, which generally isn’t visible from above when the cover 10 is in use.

[0034] The first and second sides 18, 20 of the base layer 12 each include a plurality of coating sub-layers applied thereto. The coating layer applied to the first side 18 of the base layer 12 includes a first sub-layer 22 adjacent the base fabric, a second sub-layer 24 provided over the first sub-layer 22, and a third sub-layer 26 provided over the second sub-layer 24. In this embodiment, the thickness of the first sub-layer 22 is nominally 32 micron, the second sub-layer 24 is nominally 32 micron and the third sub-layer 26 is nominally 16 micron. The total nominal thickness of the first side 18 is 80 micron. The coating layer applied to the second side 20 of the base layer 12 includes a first sub-layer 28 adjacent the base fabric, a second sub-layer 30 provided over the first sub-layer 28, and a third sub-layer 32 provided over the second sub-layer 30. In this embodiment, the thickness of the first sub-layer 28 is nominally 32 micron, the second sub-layer 30 is nominally 32 micron and the third sub-layer 32 is nominally 16 micron. The total nominal thickness of the second side 20 is 80 micron. In the illustrated embodiment, the second side 20 is sky blue in colour and the first side 18 is grey in colour, although these specific colours are in no way intended to limit the scope of the invention. Other colours may be utilised.

[0035] In the illustrated embodiment, the first sub-layer 22 includes approximately 12%, by weight, of recycled polypropylene; the second sub-layer 22 includes approximately 24%, by weight, of recycled polypropylene; and the third sub-layer 26 include substantially no recycled polypropylene. However, as stated earlier, these amounts can be varied without departing from the invention.

[0036] It is to be appreciated that the percentage, by weight, of recycled polypropylene in the second sub-layer 24 is greater than the percentage, by weight, of recycled polypropylene in the adjacent first and third sub-layers 22, 26. It is generally preferred to have the highest concentration of recycled polypropylene in sub-layer 24 sandwiched between sub-layers 22 and 26, because the impact of the recycled material may be minimised in terms of critical performance criteria such as coating <1ilename> 8 2016225909 09 Sep 2016 adhesion, weather resistance, weldability and flex resistance. In this regard, it is to be appreciated that virgin grade polypropylene generally provides better performance in terms of coating adhesion, weather resistance, weldability and flex resistance than is possible from recycled polypropylene.

[0037] Further, it is to be appreciated that, in general, the percentage, by weight, of recycled polypropylene in the third-sub-layer 26 is preferably less than the percentage, by weight, of recycled polypropylene in the first and second sublayers 22, 24, again to generally maximise the performance characteristics of the cover 10 when utilising recycled polypropylene.

[0038] In the illustrated embodiment, the first sub-layer 28 provided on the second side 20 of the base layer 12 includes between approximately 12% and 24%, by weight, of recycled polypropylene; the second sub-layer 30 includes between approximately 24% and 38%, by weight, of recycled polypropylene; and the third sublayer 32 includes approximately 8%, by weight, of recycled polypropylene.

[0039] From the aforementioned paragraph, it is to be appreciated that the percentage, by weight, of recycled polypropylene in the second sub-layer 30 is greater than the percentage, by weight, of recycled polypropylene in the first and third sub-layers 28, 32; and that the percentage, by weight, of recycled polypropylene in the third-sub-layer 32 is less than the percentage, by weight, of recycled polypropylene in the first and second sublayers 28, 30, in order to generally maximise the aforementioned performance characteristics of the cover 10 when utilising recycled polypropylene.

[0040] In the illustrated embodiment, the base layer 12 is co-extrusion coated with each of the sub-layers 22, 24, 26, 28, 30, 32. However, other manufacturing techniques may be utilised if desired.

[0041] The present invention provides the considerable benefit of utilising end-of-life grain covers in the manufacture of new grain covers. The resultant grain cover is comparable in terms of performance criteria to existing grain cover designs and, indeed, may be an improvement over existing grain cover designs in at least some performance criteria. <filename> 9 2016225909 09 Sep 2016 [0042] Desirably, utilising end-of-life grain covers in the manufacture of new grain covers results in less land fill, as end-of-life grain covers typically end up as land fill. Thus, the unique grain cover of the present invention is better for the environment, and well as being potentially more cost effective to manufacture.

[0043] The applicant’s multi-layered coating of their inventive grain covers is considered unique, and can be used to maximise the recycled polypropylene content within a central layer of the coating layer, such that it minimises any potential reduction in cover performance criteria.

[0044] Having a multi-layered coating is also desirable because it allows the coating layer to be tailored in an effort to optimise any particularly desired coating performance criteria. It is to be appreciated that additives may be included in the coating layer, one or more of the coating sub-layers or the base layer so as to enhance certain performance criteria, if desired.

[0045] It is to be understood that various alterations, modifications and/or additions may be introduced into the construction and arrangement of the parts previously described without departing from the spirit or ambit of this invention. <filename>

Claims (22)

1. The Claims Defining The Invention Are As Follows:

   1. A cover suitable for covering grain, including: a base layer, and a coating layer applied to the base layer, the coating layer including recycled polypropylene or recycled polyethylene.
2. 2. A cover suitable for covering grain according to claim 1, wherein coating layer includes: a blend of recycled polypropylene and a virgin grade polypropylene; or a blend of recycled polyethylene and a virgin grade polyethylene.
3. 3. A cover suitable for covering grain according to claim 1 or 2, wherein the coating layer is applied to a first side of the base layer and to an opposing second side of the base layer.
4. 4. A cover suitable for covering grain according to claim 3, wherein the coating layer applied to each of the first and second sides of the base layer includes a plurality of coating sub-layers.
5. 5. A cover suitable for covering grain according to claim 3 or 4, wherein the coating layer applied to each of the first and second sides of the base layer includes a first sub-layer adjacent the base fabric, a second sub-layer provided over the first sub-layer, and a third sub-layer provided over the second sublayer.
6. 6. A cover suitable for covering grain according to claim 5, wherein the percentage, by weight, of recycled polypropylene or recycled polyethylene in the second sub-layer of the coating layer applied to the first side of the base layer is greater than the percentage, by weight, of recycled polypropylene or recycled polyethylene in the first and third sub-layers applied to the first side of the base layer.
7. 7. A cover suitable for covering grain according to claim 5 or 6, wherein the percentage, by weight, of recycled polypropylene or recycled polyethylene in the third-sub-layer of the coating layer applied to the first side of the base layer is less than the percentage, by weight, of recycled polypropylene or recycled polyethylene in the first and second sublayers applied to the first side of the base layer.
8. 8. A cover suitable for covering grain according to any one of claims 5 to 7, wherein: the first sub-layer provided on the first side of the base layer includes between approximately 10%, by weight, of recycled polypropylene or recycled polyethylene and approximately 40%, by weight, of recycled polypropylene or recycled polyethylene; the second sub-layer provided on the first side of the base layer includes between approximately 20%, by weight, of recycled polypropylene or recycled polyethylene, and approximately 60%, by weight, of recycled polypropylene or recycled polyethylene; and the third sub-layer provided on the first side of the base layer includes less than 20%, by weight, of recycled polypropylene or recycled polyethylene.
9. 9. A cover suitable for covering grain according to claim 8, wherein: the first sub-layer provided on the first side of the base layer includes approximately 12%, by weight, of recycled polypropylene or recycled polyethylene; the second sub-layer provided on the first side of the base layer includes approximately 24%, by weight, of recycled polypropylene or recycled polyethylene; and the third sub-layer provided on the first side of the base layer includes substantially no recycled polypropylene or recycled polyethylene.
10. 10. A cover suitable for covering grain according to any one of claims 5 to 9, wherein the percentage, by weight, of recycled polypropylene or recycled polyethylene in the second sub-layer of the coating layer applied to the second side of the base layer is greater than the percentage, by weight, of recycled polypropylene or recycled polyethylene in the first and third sub-layers applied to the second side of the base layer.
11. 11. A cover suitable for covering grain according to any one of claim 5 to 10, wherein the percentage, by weight, of recycled polypropylene or recycled polyethylene in the third-sub-layer of the coating layer applied to the second side of the base layer is less than the percentage, by weight, of recycled polypropylene or recycled polyethylene in the first and second sublayers applied to the second side of the base layer.
12. 12. A cover suitable for covering grain according to any one of claims 5 to 11, wherein: the first sub-layer provided on the second side of the base layer includes between approximately 10% and 40%, by weight, of recycled polypropylene or recycled polyethylene; the second sub-layer provided on the second side of the base layer includes between approximately 20% and 60%, by weight, of recycled polypropylene or recycled polyethylene; and the third sub-layer provided on the second side of the base layer includes up to approximately 40%, by weight, of recycled polypropylene or recycled polyethylene.
13. 13. A cover suitable for covering grain according to claim 12, wherein: the first sub-layer provided on the second side of the base layer includes between approximately 12% and 24%, by weight, of recycled polypropylene or recycled polyethylene; the second sub-layer provided on the second side of the base layer includes between approximately 24% and 38%, by weight, of recycled polypropylene or recycled polyethylene; and the third sub-layer provided on the second side of the base layer includes approximately 8%, by weight, of recycled polypropylene or recycled polyethylene.
14. 14. A cover suitable for covering grain according to any one of the preceding claims, wherein manufacture of the cover includes the base layer being coextrusion coated with the coating layer.
15. 15. A cover suitable for covering grain according to any one of claims 5 to 14, wherein manufacture of the cover includes the base layer being co-extrusion coated with each sub-layer of the first and second sides of the coating layer.
16. 16. A cover suitable for covering grain according to any one of the preceding claims, wherein the recycled polypropylene or recycled polyethylene is at least partially recycled from at least one end-of-life grain cover.
17. 17. A cover suitable for covering grain according to claim 16, wherein the recycled polypropylene or recycled polyethylene is at least substantially recycled from at least one end-of-life grain cover.
18. 18. A cover suitable for covering grain according to any one of the preceding claims, wherein the recycled polypropylene or recycled polyethylene has a melt flow index of between approximately 10 and approximately 30.
19. 19. A cover suitable for covering grain according to any one of the preceding claims, wherein the flexural modulus of the recycled polypropylene or recycled polyethylene is between approximately 100 Mpa and approximately 400Mpa.
20. 20. A cover suitable for covering grain according to any one of the preceding claims, wherein the base layer includes a base fabric woven from polypropylene fibres or polyethylene fibres.
21. 21. A cover suitable for covering grain according to claim 20, wherein the base fabric is woven from high-tenacity polypropylene fibres or high-tenacity polyethylene fibres.
22. 22. A cover suitable for covering grain according to any one of the preceding claims, wherein the woven base fabric has a weave density of approximately 20 x 20 yarns/inch.