Abstract
Compostable cutlery utensils made by forming a pliable composite sheet having an internal substrate of overlaying food-grade paper sheets of collective number and thickness suitable for making a required item of cutlery, the internal paper sheets each being coated with a settable food-grade adhesive substance, such as by being dipped into a bath of liquid glue, applying an outer covering of food-grade paper to each major external side of the substrate to form a pliable composite sheet, thereafter forming the shape of the utensil, such as by the use of a two-part mould in the collective shape and size of the required utensil, removing, such as by cutting, the formed utensil from the composite sheet before the adhesive has set, and thereafter allowing or causing the adhesive substance to set to thereby produce a rigid compostable cutlery utensil.
Claims
1. A method of making compostable cutlery utensils (4, 10), the method including the steps, in any convenient order, of forming a pliable composite sheet (13) comprised of an internal substrate of overlaying food-grade paper sheets (7) of collective number and thickness suitable for making a required item of cutlery, the internal paper sheets (7) each being coated with a settable food-grade adhesive substance, such as by being dipped into a bath of liquid glue, applying an outer covering (8, 9) of food-grade paper to each major external side of the substrate to form a pliable composite sheet, thereafter forming the shape of the utensil, such as by the use of a two-part mould (17, 18) in the collective shape and size of the required utensil, removing, such as by cutting, the formed utensil from the composite sheet before the adhesive has set, and thereafter allowing or causing the adhesive substance to set to thereby produce a rigid compostable cutlery utensil (4, 10).
2. A method according to claim 1, wherein the number of sheets in the substrate for forming utensils in the shape of cutlery is between 6 and 10 such sheets.
3. A method according to claim 1, wherein the number of sheets in the substrate for forming utensils in the shape of cutlery is between 7 and 9 such sheets.
4. A method according to claim 1, wherein the outermost paper sheets (8, 9) covering the composite multi-layer substrate (7) are not coated with adhesive.
5. A method according to claim 1, wherein the outer covering sheets (8, 9) are thinner than the innermost sheets of the substrate (7).
6. A method according to claim 5, the innermost sheets (7) each being about 120 g and the outermost sheets (8, 9) being about 63 g.
7. A method according to claim 1, wherein the outermost sheets of paper (8, 9) are provided with a food-grade waterproofing agent such as oil, wax or acrylic.
8. A method according to claim 1, wherein the adhesive used in the manufacturing process is UV curable.
9. A method according to claim 8, further including the further step of forming the utensil while the adhesive is still wet or is otherwise not set or cured and thereafter causing the adhesive to harden by exposing it to UV radiation.
10. A composite cutlery utensil (4, 10) made in accordance with the method of claim 1.
Description
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0014] The invention will now be described, by way of example only, with reference to the accompanying drawings in which:
[0015] FIG. 1 is a perspective view of a prior art disposable spoon made of plastics,
[0016] FIG. 2 is a perspective view of a disposable spoon made in accordance with the method of the invention with a full 3D curve to the mould,
[0017] FIG. 3 is an enlarged sectional view across A-A of the spoon in FIG. 2,
[0018] FIG. 4 is a perspective view of a disposable knife made in accordance with the method of the invention cut flat with a shaped edge to the mould,
[0019] FIG. 5 is a schematic view of a method of making a plurality of disposable forks according to the invention.
DETAILED DESCRIPTION
[0020] Referring firstly to FIG. 1 there is shown a conventional plastics disposable spoon 1 comprising a handle 2 and a dish-shaped serving end 3 for scooping and serving foodstuffs (not shown) or stirring liquids. The handle 2 is in the shape of an elongate inverted channel to improve its rigidity. The spoon 1 is easily manufactured by plastics material being heated to a suitable temperature and then injection moulded within a two-part mould whereafter, upon cooling, the spoon 1 is ejected from the mould. Such spoons and indeed other items of cutlery including knives, forks and drinks stirrers are inexpensive to make and provide the user with the convenience of being disposable after use although, as is well-known, such cutlery is not biodegradable in the generally accepted sense and the plastics itself is derived from oil, being a non-renewable energy source.
[0021] In FIG. 2 there is shown a disposable spoon 4 made in accordance with the method of the invention, the spoon having a handle 5 and a dish-shaped serving end 6. The handle 5 is in the shape of an elongate trough or channel to improve rigidity.
[0022] FIG. 3 is a part-sectional front view of the spoon 4 of FIG. 2 across section A-A in which it will be seen that it comprises a composite inner substrate 7 of over-laying food-grade paper sheets, typically seven such sheets, sandwiched between respectively upper 8 and lower 9 outer food-grade paper sheets, typically thinner than the sheets of the substrate 7 and typically coated on their outer surface with a waterproofing agent such as natural wax or food-grade oil. The thinner outer sheets 8,9, which may typically be half the thickness of the sheets of the substrate 7, are sufficiently thin so as to allow for the peripheral edges of the utensil to be cut in a clean and detailed manner even to the extent of providing a cutting or piercing surface in the case of, respectively, a knife and fork. The outer sheets 8,9 may also be over-printed with food-grade ink or dye for decorative purposes and/or for promotional placement, such as being printed with the name of the establishment on one or both sides. The paper sheets within the substrate 7 are connected together by an adhesive such as Henkel Adhesive AQUENCE BG 9040 LM (not shown) which, once set or cured, provides the substrate 7 with sufficient stiffness or rigidity such that the spoon 4 can be used for scooping, stirring or serving foodstuffs and beverages as the case may be. In this respect, it is believed that by combining a large number of paper sheets glued together to form a composite substrate with sufficient thickness or volume whereby to permit the cutlery item to perform its intended function, the substrate itself is surprisingly rigid when set or cured and in many respects its mechanical properties including strength and stiffness provides a construction that is comparable to plywood despite the fact that the paper sheets have no discernible grain preferentially imparting stiffness in one direction, as is the case with wood veneer used in the construction of plywood. In contrast, it has been found that forming a utensil such as the spoon 4 from a single solid substrate of paper or cardboard of equal thickness to the substrate 7 produces a substantially weaker utensil which is not fit for purpose. It is therefore believed that the mechanical strength of the substrate 7 is derived from an unexpected stiffening effect when multiple thin layers of food-grade paper are glued together, shaped or cut to form a required utensil, and then cured or otherwise allowed to set, with the respective layers of adhesive collectively imparting a granular structure to the cutlery item, providing it with sufficient strength and rigidity to an extent comparable with disposable cutlery items made from plastics.
[0023] In FIG. 4 there is shown a perspective view of an item of disposable cutlery made in accordance with the method of the invention in the form of a table knife 10 which, in this instance, unlike the substantially 3-D shape of the spoon 4 described in FIGS. 2 and 3, is instead generally planar, having a handle 11 at one end which merges with a large serrated blade 12 at its other end, the somewhat chunky design contributing to the rigidity of the knife 10 to the extent that it requires no separate means of mechanical reinforcement, such as through the use of ribs or channels.
[0024] In FIG. 5 there is shown a schematic view of making a plurality of forks in accordance with one method of the invention, although it will be understood that other methods, including continuous forming of utensils may be used. In the drawing it will be seen that a prepared composite sheet 13 is moving towards a utensil-forming station shown generally at 14 comprising an upper mould half 15 and a lower mould half 16, each having respectively opposite cutlery item forming and cutting surfaces 17, 18 for forming, in this instance, a plurality of forks 19. The prepared composite sheet 13 is preferably made by drawing thin ribbon of food-grade paper from a respective set of rollers, dipping each innermost ribbon of paper in a bath of a suitable liquid adhesive such as Henkel Adhesive AQUENCE BG 9040 LM and thereafter overlying a required number of ribbons of paper including the outermost layers to form the client substrate 7 and cutting into a required length before being placed between the upper and lower mould halves 15, 16 so that when they are clamped together in the direction arrowed the pliability of the sheet 13 allows it to form to the required shape of cutlery, whereafter each item of cutlery is cut while the upper and lower mould halves 15, 16 are still clamped together. When the mould halves 15, 16 are then separated the moulded and cut items of cutlery, in this case a plurality of forks 19, are released from the sheet 13 to thereafter be moved along a conveyor 20 in the direction arrowed to an adhesive drying or curing station 21, such as a UV chamber of sufficient length to ensure that UV-settable adhesive between the various layers of paper making up the item of cutlery can set or cure before the cutlery drops off the end of the conveyor 20.
[0025] From the foregoing it will be seen that cutlery made in accordance with the invention is both fit for purpose in being strong enough and/or sharp enough for food handling, but is also disposable to the extent of even being compostable, that is to say, the cutlery will easily biodegrade without being subjected to any further industrial processes, such as are necessary when disposing of cutlery items made of PVA, even to the extent that, after use, cutlery made in accordance with the invention may be deposited on a compost heap comprising vegetable waste matter and lawn cuttings. The invention is therefore a considerable improvement over the prior art in that once the items of cutlery have been manufactured in accordance with the method of the invention they will naturally biodegrade even if disposed of in a landfill site.
