GB2495310A - Method of making article from grass and fumed silica - Google Patents

Abstract

A method of making an article from grass comprising mixing grass with fumed silica to form a mixed feed and compressing or moulding said mixed feed to form a rigid structure. Preferably, the grass can be mown grass or grass produced by grinding commercially available grass pellets. The ratio of grass to fumed silica is in the range of 140:1 to 30:1 by weight. Preferably, part or all of the grass comprises grass pellets ground to a particle size in the range of 0-3mm; and the moisture content is reduced to a value in the range of 4 10% by weight and total sugars content in the range of 1.5-4% by weight. The article formed may be coated with a wax or varnish. Articles manufactured according to the method comprising memorabilia or golf tees are further provided.

Description

A Method of Making an Article from Grass

Background to Invention.

Using grass cuttings to make naturally degradable articles such as golf tees is known (WO 94/25121 Eco Presence). However, such articles are friable and likely to crumble and disintegrate during storage and before use.

The present invention relates to an improved method of making articles from grass; in particular, making such articles that are resistant to physical degradation during storage and before use and that do not readily become friable and so likely to crumble.

The invention can also be adapted to produce memorabilia from revered lawns. Thus, for example, a tennis fan could purchase a plaque or a like product, which contains grass that has been mown from the famous Wimbledon Centre Court.

Summary of Invention

In one aspect the invention is a method of making an article from grass comprising mixing grass with fumed silica to form a mixed feed and compressing or moulding said mixed feed to form a rigid structure. Normally mowed grass cuttings are used as the source of grass. Such cuttings are preferably dried and sized prior to mixing.

Preferably, prior to mixing with the fumed silica, the moisture content of the grass is reduced to a value in the range 4-10% by weight, and more preferably 6-8% by weight. Preferably the grass has a total sugars content in the range 1.5 to 4% by weight. Only a relatively small proportion of fumed silica is required. Preferably, the ratio of grass to fumed silica is in the range 140:1 to 30:1 by weight, and preferably in the range 100:1 to 50:1 by weight. The mixed feed is preferably pressed between an upper and lower mould. Preferably, the mixed feed is compressed in a press under a pressure in the range of 100-500 MPa, and more preferably in the range 150-400 MPa.

Often it is convenient to use commercially available pellets to provide the source of grass. In this event such pellets are ground and screened prior to mixing with the uuimed silica. Preferably, a part or the whole of the grass comprises grass pellets ground to a particle size in the range 0-3mm. In some cases it is desirable to apply a protective coating to the moulded article; for example by coating the article with wax or varnish; or by applying a decorative coloured coating. The coating may be applied in liquid form; for example molten beeswax.

The fumed silica used in the above method is preferably Cabosil TM available from Cabot Corporation, Tuscola, Illinois, USA. Fumed silica is made by the vapour phase hydrolysis of silicon tetrachloride. It is used particularly in the pharmaceutical and cosmetics industries; in particular as a flow inducing additive.

In another aspect the invention comprises a moulded memorabilia article made by the above method. For example such an article may be made partly from grass from the Old Trafford football ground to provide a Manchester United Football Club memorabilia item.

In another aspect the invention may comprise a degradable golf tee made according to the above method. Such a tee provides environmental advantages over commonly used plastic tees.

In another aspect the invention comprises a method of making an article from grass comprising mixing mown grass, or grass produced by grinding commercially available grass pellets, with fumed silica to form a mixed feed and compressing or moulding said mixed feed to form a rigid structure.

Brief Description of the ILiyption

A preferred embodiment of the invention will now be described by reference to the following diagrammatic drawings, in which: Figure 1 shows a simplified process flow diagram for apparatus that may be employed for undertaking the method of the invention; Figure 2 shows a more detailed diagram for preparation of feeds prior to moulding or compression: Figures 3(a)-(c) diagrammatically show how items may be continuously moulded; and Figure 4 shows a golf tee made according to the method of the invention.

Detailed Description

An embodiment of the present invention will now be described by reference to Figure 1, which shows a simplified apparatus that is suitable for undertaking the claimed method. The apparatus comprises: a main grass feed storage hopper (10) with a removable cover (lOa). The main grass feed storage hopper (10) is typically used to store grass pellets (GP). Such pellets are commercially available; for example supplied in 25 kg bags by Poucher & Sons, Bardney Dairies, Wragby Market, Lincolnshire LN8 5JW, UK. A second storage hopper (20), also with a removable cover (20a) is used to store fumed silica (PS). As a relatively small proportion of silica is required to be added, the second storage hopper (20) can be small in size compared with the main grass feed storage hopper (10).

Grass pellets (OP) stored in the main grass feed hopper (10) may flow by gravity through a lower conical section (12), via a conduit (14) to a rotary chipper (16), where the pellets are ground and also pass through a sieve (16) typically with a mesh size of 3 mm. The ground and sized grass then falls by gravity through a further conduit (18) and enters a rotary mixer/screen (40).

Fumed silica (FS) stored as a powder in a second storage hopper (20) may flow through a lower conical section (22), and then via a conduit (24) to a motorised auger (26), the speed of which is controlled/set in order to obtain the desired weight ratio of fumed silica to grass. Fumed silica then falls by gravity through a fUrther conduit (28) and enters the rotary mixer/screen (40) where it combines with grass that flows by gravity through conduit 18.

The rotary mixer/screen (40) may comprise an inner cylindrical sieve (42) that in use is rotated about a horizontal axis (not shown) by means of a drive motor (44). Mixed and sized feed that has passed through the sieve into the rotating cylindrical portion (42) exits this portion (42) through a further conduit (46) and then falls by gravity into a press feed hopper (50) which again has a lower conical portion (52).

Mixed prepared feed (MF) is then transported (54) to either a press (56) or another type of compression stage (not shown) where it is moulded to form a desired article.

Providing that the press feed hopper (50) is kept at least partially filled with mixed feed (MF) this press or compression stage may operate continuously. Thus, the main grass feed hopper (10) and the second storage hopper (20) are typically periodically charged in such a way that the press feed hopper (50) never runs empty.

The sieves within the rotary chipper (16) and the rotary mixer/screen (40) may produce an oversized portion (not shown); in which case, the oversized portion may be recycled to an upstream storage vessel, or alternatively rejected.

Table I (see below) shows individual process steps for using the above apparatus to manufacture golf tees according to one embodiment of the method of the present invention.

A preferred embodiment of the invention will now be described by reference to Figures 2 and 3. Figure 2 shows and apparatus suitable for making memorabilia articles from grass. Some of the equipment items shown in Figure 2 are the same as shown in Figure 1; in which case they share the same reference number. When highly valued grass (for example from a revered pitch or lawn) is used to manufacture memorabilia articles, it is often desirable to supplement this with more available grass prepared by grinding and sieving commercially available (see above) grass pellets.

Thus, Figure 2 shows an additional (highly valued) grass storage hopper (30) with a removable cover (30a).

Highly valued grass (for example as obtained by mowing a revered lawn or pitch) may flow through a lower conical section (32) or feed hopper 30 via a conduit (34) to a motorised auger (36), the speed of which he is controlled in order to obtain the desired weight ratio of revered grass in the mixed feed (ME). The valued grass (VG) then enters the rotary mixer/screen (40) via conduit 38.

Figure 2, also shows an additional (intermediate) storage hopper (60), located between the rotary mixer/screen (40) exit conduit (46) and the press feed hopper (50). This intermediate storage hopper (60) allows the mixed feed to be sampled prior to entering the press feed hopper (50) and also provides reserve storage of mixed feed (MF).

Again, the mixed feed (MF.) is then transported (54) to a press (56) or compression means (not shown), This transport and press (56) will now be described by reference to Figures 3(a) to 3(c). Figures 3 show how mixed feed may be transported to a hydraulic press.

Some or all of the vessels (10, 20,30) may be agitated (for example by paddles or stirrers) in order to promote homogeneity of the contents and/or encourage steady flow of solids as they flow through conduits (8, 28, 38).

Figure 3(a) shows the start of a sequence which is continuously repeated. Mixed feed (MF.) exits the mixed feed hopper lower conical portion (52) and flows under gravity through a further conduit (54) into the well (56) of a sliding member (58) located immediately underneath a lower portion of the further conduit (54). The sliding member (58) slides over a table (70), the purpose of which is to provide a floor for the well (56). In addition, when the well (56) is located immediately below the further conduit (54) the exit of the fUrther conduit (54) and the upper portion of the well (56) provide a seal. Thus, in this position mixed feed may flow under gravity (only) into the well (56).

Figure 3(b) shows the next stage of the sequence, where the sliding member (58) has moved horizontally such that the exit of the mixed feed hopper (50) is now sealed by the sliding member (58) and the grass contained within the well (56) has moved across a table (70) and is now located directly above a mould (72) that may be attached to the table (70) or may be located immediately adjacent to a side of the table (70). As the lower portion of the well (56) is open, mixed feed falls from the well (56) into the empty portions of the mould (72). In order to ensure that the mould (72) is fully filled it is preferable to arrange that at the volume of grass in the the well (56) exceeds the volume of the empty portions of mould (72). Part of the mixed feed (MF) within the well (56) falls into the mould (72) but preferably there remains an excess of mixed feed (R) within the well (56).

Figure 3(c) shows the next stage of the sequence where the sliding member (58) is withdrawn (eventually to the position shown in figure 3(a)); this allows a top tool (74) to descend vertically into the mould (72); hydraulic pressure being exerted upon the top tool in order to press the mixed feed within the lower mould (72) and thus obtained moulded articles (not shown).

Figure 4 shows a cross section view of a golf tee made according to the method of the invention.

TABLE I

Quality commercially grown $ Freshly mown grass from named and pcllctised grass. Fumed Silica (e.g. Cabosil M-5) source.

kg bags. Surface area 200 * 25sq m per gram. Examples: Representative variety; pH (4% in 1-120) 3.8-4.3 Old Trafford pitch.

Lucerne' (Manchester United F C) Typically Protein 18% Brabazon Golf Course.

Fibre 25% I (Belfry Leisure Complex) Sugar 2% Water 6% 1 __ l' Additive Flopper Grinder lopper Contains: Agitator to prevent settling. TableDntr Pellets reduced in a rotary Metering unit, Water reduction to 6%.

chippcr to particle SiZe Delivers fumed silica to Rotary Sieve in 0-3mm. proportion 0.7(03.5 g fumed silica per lOOg of Manual removal of foreign grass. material and unusable lumps.

Metering Unit Proportions depend on specific product. c-7 I

I Oversize returned to Grinder Holding Flopper I-topper. 4 Sieve P Sample point for quality control, [ Scrcen size 3mm __________________________ ___________________________.Jr EJ'oQi Slide Press Hopper Accepts correct quantity of mixed First motion: Slide delivers mixed Fills Slide Well with mixed medium. (I of 3 tee sizes) I medium to Press Tool bottom die. medium. Slide position I. J Slide position 2.

1 _______________________________________________________ de Second Motion: Slide Press inserts top die and applies appropriate pressure for product; typically in the retracts to clear tool. range 260 MPa to 300 MPg. iop die retracts clear. Ejectors lift produci from Slide Clear position 3. bottom die. Slide

Third motion: Slide retracts fully to sequence start (position I) under Press Flopper. Slide Well refills.

As Slide moves from Clear position 3, attached lingers lift tees from bottom tool and passes them to conveyor.

(One complete manufacturing cycle. Finishing and packing follows.) Wax Spray Line Visual inspection point. Rejects to cornposting bin. Tees are hand loaded onto vertical conveyor-mounted spindles. Each tee is rotatcd under the spray head and receives a light coat of liquid beeswax. Conveyor auto-unloads into Packaging.

Packaging Boxcs are hand folded and tees packed typically 9 per box.

Boxes are packed 300 per carton. (5 x 20 x 3 layers.) 1'

Claims (1)

1. <claim-text>CLAIMSI. A method of making an article from grass comprising mixing grass with fumed silica to form a mixed feed and compressing or moulding said mixed feed to form a rigid structure.</claim-text> <claim-text>2. A method according to Claim 1 wherein the ratio of grass to fumed silica is in the range 140:1 to 30:1 by weight.</claim-text> <claim-text>3. A method according to Claim 1 or 2 where the mixed feed is compressed in a press under a pressure in the range of 100-500 MPa and preferably in the range 150-400 MPa.</claim-text> <claim-text>4. A method according to any preceding claim where a part or the whole of the grass comprises grass pellets ground to a particle size in the range 0-3mm.</claim-text> <claim-text>5. A method according to any preceding claim where, prior to mixing with the fumed silica, the moisture content of the grass is reduced to a value in the range 4-10% by weight, and preferably 6-8% by weight.</claim-text> <claim-text>6. A method according to any preceding claim where the grass has a total sugars content in the range 1.5 to 4% by weight.</claim-text> <claim-text>7. A method according to any preceding claim wherein the article formed by compressing or moulding said mixed feed is coated with wax or varnish.</claim-text> <claim-text>8. An article manufactured according to the method of any of Claims I to 7 where the article is a memorabilia.</claim-text> <claim-text>9. An article manufactured according to the method of any of Claims 1 to 7 where the article is a golf tee.</claim-text>