Processing method and products produced thereby

Abstract

The present disclosure provides a method of processing shell material. Shell material processed in accordance with the methods disclosed herein may be biodegradable and may further represent a new type of useful material. By way of example, the processed shell material may be useable as a material to make useful materials, items, objects and/or tools.

Claims

1. A method of processing shell material to provide a biodegradable material, said method comprising the steps of: a) granulating shell material; b) contacting the granulated shell material with a binding agent, wherein the binding agent comprises cellulose microfibers/fibrils (CMF), cellulose nanofibers/fibrils (CNF), and nanocrystalline cellulose, and combination thereof; and c) drying the granulated shell material/binding agent mix to obtain a dried mix, wherein the drying step c) comprises filtering, freeze-drying, air drying, or combinations thereof; wherein the dried mix is a biodegradable material, wherein the shell material is selected from the group consisting of eggshell, body shell from crustaceans and body shell from molluscs, and wherein the ratio of shell material:binding agent is between 5:1 to 1:5 by weight.

2. The method of claim 1, wherein step a) further comprises separating the granulated shell material by granule size.

3. The method of claim 1, wherein the granulated shell material comprises granules less than 200 μm in size.

4. The method of claim 1, wherein the granulated shell material comprises granules less than 124 μm in size.

5. The method of claim 1, wherein the granulated shell material comprises granules less than 74 μm in size.

6. The method of claim 1, wherein the granulated shell material comprises granule sizes within any one of the ranges <53 μm, 54-74 μm, 75-124 μm, or 125-249 μm.

7. The method of claim 1, wherein the method further comprises the use of a flow agent and wherein the granulated shell material and the binding agent are further contacted with the flow agent.

8. The method of claim 7, wherein the flow agent is water.

9. The method of claim 1, wherein the binding agent is provided in the form of a suspension and wherein the granulated shell material is contacted with the binding agent suspension.

10. The method of claim 1, wherein the granulated shell material is prepared as a suspension before contacting step b) and wherein the granulated shell material suspension is contacted with the binding agent.

11. The method claim 1, wherein the method further includes a molding step.

12. The method of claim 1, wherein the shell material comprises eggshell, langoustine shell, or both.

13. The method of claim 1, wherein the binding agent is cellulose micro_fibrils (CMF), cellulose nano fibrils (CNF), or both.

14. The method of claim 1, wherein the ratio of shell material:binding agent is 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5 by weight.

15. The method of claim 1, wherein the method comprises an additional step of adding a dye or colorant and wherein the colorant or dye is added after drying step c).

16. The method of claim 1, wherein a hydrophobic coating is applied to the biodegradable material and the hydrophobic coating is polylactic acid.

17. The method of claim 1, wherein the method does not require the use of: (i) filler materials, inorganic carbonates, clays and/or coal residues; (ii) dispersing agents, maleic acid and/or citric acid; and/or (iii) synthesized calcium carbonate, natural ground calcium carbonate or surface modified calcium carbonate.

Description

DETAILED DESCRIPTION

(1) The present invention will now be described in detail with reference to the following figures which show:

(2) FIG. 1 presents an embodiment of the invention as a flow diagram.

(3) FIG. 2 is a photograph of a product obtained according to a method of the invention. In this example, a ratio of 1:0.39 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibril mix is either air dried (left sample) or oven dried (right sample).

(4) FIG. 3 is a graph of the extension (mM) as a function of the load applied (N) of a product obtained according to a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is air dried.

(5) FIG. 4 is a graph of the extension (mM) as a function of the load applied (N) of a product obtained according to a method of the invention, in which a ratio of 5:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is air dried.

(6) FIG. 5 is a photograph of a product obtained according to a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is freeze-dried.

(7) FIG. 6 is a photograph of a product obtained according to a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is air dried. The sample on the right is coated with a hydrophobic solution comprising 1% polylactic acid in chloroform.

(8) FIG. 7 is a photograph of a product obtained according to a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the two materials are contacted and air dried. The samples are then dyed using waste coffee (left sample), beetroot waste (middle sample) and red cabbage waste (right sample).

(9) FIG. 8 is a photograph of a product obtained according to a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is pressed (using a coffee press) and subjected to further moisture removal by osmosis/diffusion using paper towels.

(10) FIG. 9 is a photograph of a material obtained by a method of the invention, in which a ratio of 3:1 eggshell (<53 μM):cellulose micro fibrils is used and the eggshell/cellulose micro fibrils mix is moulded and heat dried using a hair drier. This moulded material has been used to produce a plate.

EXEMPLIFICATION OF THE INVENTION

(11) Ground eggshell powder obtained from the UK-based egg processing company JUST EGG was initially sorted into six granule size groups, using a sieve shaker: 1. >500 microns 2. 250-499 microns 3. 125-249 microns 4. 75-124 microns 5. 54-74 microns 6. <53 microns

(12) The two specific groups of granule sizes that were used for experimentation consisted of: 1. 54-249 microns 2. <53 microns

Example 1: Proof of Concept

(13) Two samples were prepared by contacting the following: 1 g of eggshell powder (<53 microns); and 39 g of 1% Cellulose Micro Fibrils (CMF) solution in water,
with a frequency based shaker (LabRAM).

(14) The resulting material was divided into two cups and dried either by air drying or by oven drying. After one week, the samples had dried to form a strong and flexible cardboard-like material (see FIG. 2). Without wishing to be bound by theory, this result appeared to indicate that the cellulose fibres were able to effectively bind the calcium carbonate from eggshells.

Example 2: Optimising the Ratio of Eggshell and Cellulose

(15) Samples were prepared according to the method used in Example 1, but with ratios of eggshell powder:CMF of 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5.

(16) The ratios comprising more CMF (for example, 1:2 to 1:5) produced materials that were more flexible whereas the ratios comprising more eggshell powder (for example, 5:1 to 2:1) produced materials that were more brittle but greater in strength.

(17) Samples with more calcium carbonate proved to be stronger. The material with the best balance of strength and flexibility was that produced with a ratio of eggshell powder:CMF of 3:1. FIGS. 3 and 4 are graphs of the extension (mM), as a function of the load applied (N) to the material obtained according to this method, in which a ratio of 3:1 or 5:1 eggshell (<53 μM):CMF was used. The more flexible material that is produced using a ratio of 3:1 is able to stretch (extend) to a greater extent than that produced using a ratio of 5:1. This results in the more flexible material withstanding a larger load (up to approximately 115 N) before it breaks, compared with the more brittle material produced using a ratio of 5:1 (that can withstand up to approximately 38 N). A ratio of eggshell powder:CMF of 3:1 provides versatile materials that may be useful in a variety of applications.

Example 3: Freeze Drying

(18) Samples were prepared according to the method used in Example 2, with the preferred ratio of 3:1 eggshell powder:CMF. Rather than air or oven drying, samples were frozen in a freezer and then dried using a freeze-drying machine which removes all the moisture whilst preserving the shape of the frozen sample.

(19) The resulting material (see FIG. 5) was light and fluffy, similar in texture to a cotton-pad (aerogel). This material is likely to have insulating properties and could be used as an insulating material in construction. Alternatively, it could be used as a pad in the cosmetics industry, for example for product (for example, make-up) application or removal. Once moulded into certain shapes, this material could also be used in protective packaging (replacing Styrofoam and plastic wrappers).

(20) The same freeze drying method was also used with eggshell granule sizes of 54-249 microns. The larger particles appeared to provide a material that was prone to crumbling.

(21) The freeze-dried material obtained with eggshell granule sizes of <53 microns was less crumbly and is a preferred material.

Example 4: Water Absorption and Hydrophobic Coatings

(22) Samples were prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1. The material was tested for absorption of water. A drop of water was contacted with the material, which was absorbed after approximately 7 minutes, indicating that the material is hydrophilic.

(23) A hydrophobic coating is necessary if the material is to withstand aqueous solutions when used in the presence of water or moisture.

(24) Bioplastic pellets of polylactic acid (PLA) were dissolved in chloroform to produce solutions comprising 6% and 3% PLA. The thicknesses of the bioplastic coatings that resulted on drying 10 mL, 7.5 mL and 5 mL of the 6% solution, and 10 mL of the 3% solution were compared. The thickness of the coating that resulted when 10 mL of the 3% solution of PLA was used appeared to be suitable, however this solution was too viscous to be used with a spray gun. Therefore, a 1% solution of PLA in chloroform was used, and sprayed via a spray gun onto the material samples that were prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1. The resulting coated materials were hydrophobic (see FIG. 6).

(25) Application of the bioplastic coating with a spray gun is advantageous, as this coating can be applied whenever needed.

Example 5: Colouring the Material

(26) Three natural colorants or dyes were used—red cabbage, beetroot and coffee.

(27) Samples were prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1. Either waste coffee grounds or red cabbage colouring was added to each sample before drying. The colouring from the red cabbage faded as the samples dried, however the colouring from the coffee grounds remained.

(28) Separate samples prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1, were dried prior to addition of the colorant. Colouring dry materials proved to give a vibrant and more vivid colour (see FIG. 7) and is the preferred dying method.

Example 6: Larger Granule Sizes

(29) Samples were prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1, and with eggshells with granule sizes of 54-249 microns rather than <53 microns.

(30) The resulting material was nicely formed and similar to that formed using eggshell granule sizes of <53 microns. The material differed in that it had a more coarse or rougher surface texture than that formed with the smaller eggshell granule sizes, and could prove useful in exfoliating applications.

(31) The eggshell granules close to the 249 micron size appeared to crumble off the material on handling. Therefore, the preferred eggshell granule size is smaller than 249 microns, preferably ⋅200 microns.

(32) The same ratio of eggshell powder:CMF of 3:1 gave the best balance of strength and flexibility and is preferred for all eggshell granule sizes.

Example 7: Pressing and Drying the Material

(33) Samples were prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1. Rather than simply air- or oven-drying, the sample was pressed in a coffee press to remove much of the water. The sample was then removed from the press and left on a paper towel to absorb the excess water, followed by oven-drying.

(34) This drying method produced similar samples as those produced with simple air- or oven-drying (see FIG. 8), but the sample dried much more quickly.

Example 8: Moulding

(35) A plate design was produced using computer numerical control and vacuum formed into a plastic tube. Holes were drilled into the mould, which was then lined with filter paper.

(36) The granulated shell waste/binding agent mix was prepared according to the method used in Example 2, with the preferred eggshell powder:CMF ratio of 3:1. The mix was then poured into the mould. The water separated from the mix by gravity filtration and the resulting material was dried using a hair drier. The material retained the plate shape of the mould (see FIG. 9).

(37) Smaller objects, for example the spork of FIG. 9, were prepared by cutting out the desired shapes from larger samples prepared according to the methods used in Example 2 and Example 7, with the preferred eggshell powder:CMF ratio of 3:1.