A PROCESS FOR PRODUCING A NON-WOVEN GRASS FIBRE PRODUCT

Abstract

A process for producing a non-woven grass fibre product comprises providing a grass fibre biomass obtained by aerobic fermentation of a meadow grass slurry and removal of digestible elements released during aerobic fermentation, mixing and shaping the grass fibre biomass to form a non-woven grass fibre mat, and binding and drying the mat to form the non-woven grass fibre product.

Claims

1. A process for producing a non-woven grass fibre product comprising the steps of: providing a grass fibre biomass obtained by aerobic fermentation of a meadow grass slurry and removal of digestible elements released during aerobic fermentation; addition of at least one non-fermented grass to the grass fibre biomass in which the mixture of non-fermented grass and grass fibre biomass contains 10-50% by weight of non-fermented grass, in which the non-fermented grass is selected from sisal, hemp, cereal or flax; mixing and shaping the mixture of non-fermented grass and grass fibre biomass to form a non-woven grass fibre mat, and binding and drying the mat to form the non-woven grass fibre product, in which the grass fibre biomass has a moisture content of 5-15% by weight, and in which the grass fibre biomass is treated to size reduce the grass fibres in the biomass.

2. A process according to claim 1, in which the grass fibre biomass is treated to size reduce the grass fibres in the biomass to a size of 1-30 mm.

3. A process according to claim 1 or 2, in which the grass fibre biomass is produced in a process comprising the steps of: mixing meadow grass and an aqueous liquid at a weight ratio of 1:1 to 50:1 to provide a slurry; incubating the slurry under conditions to allow aerobic fermentation of the grass by microorganisms naturally present in the grass to provide a grass fibre biomass solid phase that is depleted in digestible elements dispersed in a liquid phase; and separation of the solid phase from the liquid phase to provide the grass fibre biomass.

4. A process according to any preceding claim, in which the mixture of non-fermented grass and grass fibre biomass comprises a fire-retardant material.

5. A process according to any preceding claim, in which the mixing and shaping step comprises an air lay process.

6. A process according to claim 5, in which the air lay process incorporates a dust extraction step and is configured to provide a non-woven grass fibre mat with a density of 30-80 Kg/m.sup.3.

7. A process according to any preceding claim, in which the binding step comprises adding a binder to the non-woven grass fibre mat prior to or during drying.

8. A process according to any preceding claim, in which the non-fermented grass is size reduced prior to addition to the grass fibre biomass.

9. A process according to any preceding claim, in which the non-fermented grass is size reduced prior to addition to the grass fibre biomass to a grass particle size of about 1-40 mm.

10. A non-woven grass fibre mat having a flexible 3-dimensional structure, and comprising: aerobically fermented meadow grass fibre biomass that is depleted in digestible material; at least one non-fermented grass selected from sisal grass, hemp grass, cereal grass or flax grass; and a binder, wherein a weight ratio of non-fermented grass to aerobically fermented meadow grass fibre biomass is about 10:90 to 50:50, and wherein the non-woven grass fibre product has a density of 30-50 Kg/m3.

11. A non-woven grass fibre mat having a flexible 3-dimensional structure, and comprising: aerobically fermented meadow grass fibre biomass that is depleted in digestible material; at least one non-fermented grass selected from sisal grass, hemp grass, cereal grass or flax grass; and a binder, wherein a weight ratio of non-fermented grass to aerobically fermented meadow grass fibre biomass is about 10:90 to 50:50, and wherein the non-woven grass fibre product has a density of 300-550 g/m2 at a thickness of 20 mm.

12. A non-woven grass fibre mat according to claim 10 or 11, including an outer cover layer selected from a polymer film or mesh cover.

13. A non-woven grass fibre mat according to any of claims 10 to 12, in which the grass fibres in the grass fibre biomass have a size of 1-30 mm.

14. A non-woven grass fibre mat according to any of claims 10 to 12, in which the non-fermented grass has a grass particle size of about 1-40 mm.

15. Use of a non-woven grass fibre mat of claim 10. as a thermal or acoustic insulation material for a building.

16. Use of a non-woven grass fibre mat of claim 11 as an acoustic insulation material for a vehicle.

17. A system for producing a non-woven grass fibre product, comprising: a fermentation module configured to produce grass fibre biomass by aerobic fermentation of a meadow grass slurry and removal of digestible elements released during aerobic fermentation; a non-fermented grass size reduction module to receive non-fermented grass and size reduce the non-fermented grass; a metering module operably connected to the fermentation module and non-fermented grass size reduction module configured to automatically meter predetermined amounts of the grass fibre biomass and non-fermented grass; a mixing and shaping module (e.g. an airlay machine) operably connected to the metering module and configured to receive the predetermined amounts of the grass and grass fibre biomass from the metering module and mix and shape to form a non-woven grass fibre mat; and a binding and drying module operably connected to the mixing and shaping module and configured to receive the non-woven grass fibre mat form the mixing and shaping module and add binder to the mat and dry the mat.

18. A system according to claim 17, comprising a size reduction module configured to receive grass fibre biomass from the fermentation module, size reduce the biomass, and deliver the size-reduced biomass to the metering module.

19. A system according to claim 17 or 18, comprising one or more of the non-fermented grass size reduction module, metering module, mixing and shaping module, and binding and drying module includes a dust extraction module.

20. A system according to claim 17, 18 or 19, comprising one or more of the non-fermented grass size reduction module, metering module, mixing and shaping module, and binding and drying module includes a spark detection module.

21. A system according to any of claims 17 to 20, comprising one or more of the non-fermented grass size reduction module, metering module, mixing and shaping module, and binding and drying module includes a metal detection module.

22. A system according to any of claims 17 to 21, comprising one or more of the non-fermented grass size reduction module, metering module, mixing and shaping module, and binding and drying module includes a fire extinguishing module.

23. A system according to any of claims 17 to 22, comprising one or more of the non-fermented grass size reduction module, metering module, mixing and shaping module, and binding and drying module includes a fire retardant addition module.

24. A system according to any of claims 17 to 23, comprising conveyors configured to convey material between modules, in which at least one or more of the conveyors comprise a dust extraction module.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0072] All publications, patents, patent applications and other references mentioned herein are hereby incorporated by reference in their entireties for all purposes as if each individual publication, patent or patent application were specifically and individually indicated to be incorporated by reference and the content thereof recited in full.

Definitions and General Preferences

[0073] Where used herein and unless specifically indicated otherwise, the following terms are intended to have the following meanings in addition to any broader (or narrower) meanings the terms might enjoy in the art:

[0074] Unless otherwise required by context, the use herein of the singular is to be read to include the plural and vice versa. The term “a” or “an” used in relation to an entity is to be read to refer to one or more of that entity. As such, the terms “a” (or “an”), “one or more,” and “at least one” are used interchangeably herein.

[0075] As used herein, the term “comprise,” or variations thereof such as “comprises” or “comprising,” are to be read to indicate the inclusion of any recited integer (e.g. a feature, element, characteristic, property, method/process step or limitation) or group of integers (e.g. features, element, characteristics, properties, method/process steps or limitations) but not the exclusion of any other integer or group of integers. Thus, as used herein the term “comprising” is inclusive or open-ended and does not exclude additional, unrecited integers or method/process steps.

[0076] “Grass fibre biomass” refers to a grass fibre product that is produced from a grass slurry (generally a mixture of meadow grass and an aqueous liquid such as water) that is subjected to aerobic fermentation under conditions that allow the fermentative microorganisms naturally present in the grass ferment the grass to provide a slurry containing a grass fibre biomass solid phase and a liquid phase. The solid phase contains grass fibre biomass that is depleted in digestible components (i.e. nutrients) and the liquid phase contains the digestible components. The solid phase is separated from the liquid phase to provide the biomass that is used in the process of the invention. The separated solid phase is generally treated to remove water (pressing and/or drying) and may also be washed and subjected to a membrane filtration process to remove minerals and organic acids. The resultant biomass is highly depleted in unwanted materials such as nutrients and is enriched in lignocellulosic material suitable for forming non-woven materials. A process for producing a grass fibre biomass is described in WO2012/023848, in particular examples 1 and 2.

[0077] “Mixing and shaping the grass fibre biomass to form a non-woven grass fibre mat” refers to a process in which the biomass optionally in combination with other ingredients such as a flame retardant, binder and non-fermented grass is formed into a 3-D web using convention non-woven processing such as airlaid, wetlaid or carding/crosslapping process. The process generally involves arranging the material on to a conveyor in the form of a mat and chemically or mechanically processing the mat to allow the fibres adhere together. Typically, the process includes one or more of a dust extraction step, spark detection and metal detection. Binder is generally added, and the mat dried to form the non-woven product. In an airlaid process, the fibres are mixed with air to form a uniform air-fibre mixture which is deposited on a moving air-permeable belt. Processing of fibrous material to produce non-woven materials is described in:

https://www.sciencedirect.com/topics/engineering/airlaid.

[0078] “Non-woven grass fibre mat” refers to the product produced from the grass fibre biomass (optionally combined with other ingredients such as the added non-fermented grass(es)) after the mixing and forming process (for example an air lay process). The mat generally has a density of 30-80 kg/m.sup.3. The mat may have a thickness of 1-200 cm, for example 1-200, 5-200, 5-150, 50-200, 50-150 cm. When used as insulation, the mat may have a thickness of 10-150 cm, 50-150 cm or 100-150 cm. When used as a paneling for a vehicle, the mat may have a thickness of 10-80 cm or 20-80 cm. When used as a packaging material, the mat may have a thickness of 5-50 cm, 5-30 cm, 50-20 cm or 5-15 cm. When used as a paneling for a vehicle, the mat may have a density of 300-550 g/m.sup.2 at a thickness of 20 mm. When used as a packaging material, the mat may have a density of 100-300, typically about 200 gram/m.sup.2 at a thickness of 7 mm. When used as insulating material, the mat may have a density of 30-50 or about 40 Kg/m.sup.3.

[0079] “Binder” refers to a material added to a mat product, often during the drying process, to adhere the fibres together. The binder may be added prior to or during drying. In any embodiment, the binder is added at an amount of about 5-15% or about 8-12% or about 10% by weight of the non-woven grass fibre mat. Suitable binders include starch, casein, latex, cellulose derivatives, synthetic resins.

[0080] “Non-woven grass fibre product” refers to the product obtained by drying and binding the non-woven grass fibre mat. The product typically has a density of 30-80 kg/m.sup.3, and/or may have a thickness of 1-200 cm or 1-100 cm. In any embodiment, the non-woven grass fibre product comprises non-fermented grass. Generally at least 10-50% (for example 5-50%, 5-40%, 5-30%, 5-20%, 5-15%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40% or 20-30%) by weight of the solids in the non-woven grass fibre product is non-fermented grass. The product may have a density of 30-80 kg/m.sup.3. The product may be a flexible, semi-rigid, or rigid. The product may take the form of a mat or a block. The product may be shaped into a panel suitable for use in a vehicle, for example door or roof panels for a vehicle cockpit, or an insulating panel for a vehicle engine bay. The product may take the form of an acoustic insulation panel, which panel may be configured for retrofitting to a wall of a room to acoustically insulate the room. The product may take the form of mattress or a cushion for a chair or sofa. The product may take the form of a packaging for an article, especially a heavy duty industrial article such as an engine, engine part, machine, or machine part. Generally, the packaging product is configured for use with articles that weigh more than 1, 5, 10, 15, 20, 30 or 40 Kg. The product may be a thermal insulation product for use in a vehicle or a building comprising a non-woven grass fibre product of the invention. The product may be an acoustic insulation product for use in a vehicle or a building comprising a non-woven grass fibre product of the invention. The product may be a packaging for products, especially for industrial items comprising a non-woven grass fibre product of the invention. The product generally has a moisture content by weight of about 5% of less, for example 1-5%, 1-4%, 1-3%, 1-4%, 2-4%, 1-3%, 2-5%, 3-5%. In one embodiment, the product comprises an outer layer, for example an outer film or mesh layer. The film or mesh may be made from a polymer material. The outer layer can protect the product from ingress of water, and also help avoid the product breaking or being mechanically eroded.

[0081] “Meadow grass” refers to grass obtained from meadows and fields and parks (also referred to as “mown grass”). It includes grass cut from urban areas including cut lawn grass and grass cut from motorway verges.

[0082] “Non-fermented grass” refers to grass that has not been subjected to aerobic fermentation and that is mixed with the grass fibre biomass prior to mixing and forming. It is generally selected from hemp, flax, cerealor sisal grass. The added grass is generally size reduced prior to addition to the biomass, typically to a grass particle size of about 1-40 mm.

[0083] “Fire retardant material” means a material that inhibits or prevents fire or flames in the product. Examples of fire retardants include borates such as boric acid and borate salts (American Borate Company). Fire retardant is generally added after the biomass is produced. It may be added at 1-20%, 5-15% or about 8-12% by weight.

EXEMPLIFICATION

[0084] The invention will now be described with reference to specific Examples. These are merely exemplary and for illustrative purposes only: they are not intended to be limiting in any way to the scope of the monopoly claimed or to the invention described. These examples constitute the best mode currently contemplated for practicing the invention.

Example 1: Preparation of Grass Fibre Biomass

[0085] A process according to a first embodiment of the invention is described in detail. The process comprises the following steps:

A. 50 Kg meadow grass which has been freshly cut (about 65% moisture by weight) is added to a container along with 50 Kg water. The container has an outlet in the base which collects liquid phase and re-circulates it to the top of the container. The container is closed to allow aerobic fermentation of the slurry for 6-10 days.
B. The liquid phase is drained from the bottom of the container leaving a wet grass fibre biomass depleted in digestible components. A weight is than placed on top of the biomass for several hours which compresses the biomass to further reduce the moisture content.
C. The biomass was then placed in a press and compressed to remove moisture until the moisture was about 50% by weight.
D. The biomass was then shredded to size reduce the grass fibres to a size of 10-20 mm.
E. The size reduced biomass was then dried in a condenser dryer at temperatures of 45-65° C. for about 100 hours until the moisture content had reached about 10% by weight.
F. A fire retardant (zinc borate) was sprayed onto the blocks at about 10% by weight of the biomass.

Example 2—Preparation of Grass Fibre Non-Woven Thermal Insulation Material

[0086] A. 100 Kg of decorticated hemp grass fibre was shredded in a conventional shredder to produce a grass fibre product having an average grass particle size of 10-20 mm and a moisture content of about 10-15% by weight.
B. 20 Kg of the decorticated shredded hemp grass fibre and 80 Kg of grass fibre biomass produced according to Example 1 are mixed with continuous dust extraction and then added into airlaid processing machine comprising a dust/fines extractor, spark detector and metal detector. The grass and biomass are mixed with air and the mixed fibres are deposited onto a conveyor to form an elongated non-woven mat having a density of about 40 Kg/m3 and a thickness of about 10 cm.
C. Binder (OC-Biobinder) is added to the mat at about 10% by weight and the mat is dried to provide a grass fibre non-woven product having a final moisture content of less than 5%. This product is in the form of a flexible batt suitable for use as thermal insulation for a building.

Example 3—Preparation of Grass Fibre Non-Woven Acoustic Insulation Boards

[0087] A. 100 Kg of decorticated hemp grass fibre was shredded in a conventional shredder to produce a grass product having an average grass particle size of 10-20 mm and a moisture content of about 13% by weight.
B. 40 Kg of the decorticated shredded hemp grass fibre and 60 Kg of grass fibre biomass produced according to Example 1 are mixed with continuous dust extraction and then added into airlaid processing machine comprising a dust/fines extractor, spark detector and metal detector. The grass and biomass are mixed with air and the mixed fibres are deposited onto a conveyor to form an elongated non-woven mat having a density of about 70 Kg/m3 and a thickness of about 3 cm.
C. Binder (OC-Biobinder) is added to the mat at about 10% weight and the mat is dried to provide a grass fibre non-woven product having a final moisture content of less than 5% This product is in the form of a rigid board and can be used as acoustic insulation for buildings or vehicles.

Example 4—Preparation of Grass Fibre Non-Woven Thermal Insulation Material

[0088] A. 100 Kg of decorticated sisal grass was shredded in a conventional shredder to produce a grass product having an average grass particle size of 10-20 mm and a moisture content of 10-15% by weight.
B. 25 Kg of the decorticated shredded sisal grass fibre and 75 Kg of grass fibre biomass produced according to Example 1 are mixed with continuous dust extraction and then added into airlaid processing machine comprising a dust/fines extractor, spark detector and metal detector. The grass and biomass are mixed with air and the mixed fibres are deposited onto a conveyor to form an elongated non-woven mat having a density of about 40 Kg/m3 and a thickness of about 10 cm.
C. Binder (OC-Biobinder) is added to the mat at about 10% by weight and the mat is dried to provide a grass fibre non-woven product having a final moisture content of less than 5%. This product is in the form of a flexible may that can be rolled up and is suitable for use as thermal insulation for a building.

Example 5—Preparation of Grass Fibre Non-Woven Packaging Material for Heavy Duty Items

[0089] A. 100 Kg of hemp grass was shredded in a conventional shredder to produce a grass product having an average grass particle size of 10-20 mm and a moisture content of 10-15% by weight.
B. 40 Kg of shredded hemp grass and 60 Kg of grass fibre biomass produced according to Example 1 are mixed with continuous dust extraction and then added into airlaid processing machine comprising a dust/fines extractor, spark detector and metal detector. The grass and biomass are mixed with air and the mixed fibres are deposited onto a conveyor to form an elongated non-woven mat having a density of about 70 Kg/m3 and a thickness of about 5 cm.
C. Binder (OC-Biobinder) is added to the mat at about 10% by weight and the mat is dried to provide a grass fibre non-woven product having a final moisture content of less than 5% by weight. This product is in the form of a rigid board that can be used as packaging material for heavy duty industrial items such as engines or engine parts as a replacement for wood fibre boards.

EQUIVALENTS

[0090] The foregoing description details presently preferred embodiments of the present invention. Numerous modifications and variations in practice thereof are expected to occur to those skilled in the art upon consideration of these descriptions. Those modifications and variations are intended to be encompassed within the claims appended hereto.