PROCESS TO PREPARE A BIODEGRADABLE PULP PRODUCT

Abstract

The invention is directed to a process to prepare a three-dimensional shaped biodegradable pulp product by (b) pressing a 3D product made of biodegradable pulp which product is coated with a water-resistant compound having a melting temperature of above 40 C. in a mould at a temperature above the melting temperature of the water-resistant compound, and (c) releasing the product from the mould and reducing the temperature to below the melting temperature of the water-resistant compound.

Claims

1. Process to prepare a three-dimensional shaped biodegradable pulp product by (b) pressing a 3D product made of biodegradable pulp which product is coated with a water-resistant compound having a melting temperature of above 40 C. in a mould at a temperature above the melting temperature of the water-resistant compound, and (c) releasing the product from the mould and reducing the temperature to below the melting temperature of the water-resistant compound.

2. Process according to claim 1, wherein the water-resistant compound is a wax having a melting temperature of between 60 C. and 120 C.

3. Process according to claim 2, wherein the wax is a paraffinic wax and/or microwax.

4. Process according to claim 1, wherein the 3D product which is coated with a water-resistant compound is obtained in a step (a) in which step the water-resistant compound is sprayed on the surface of a starting three-dimensional shaped biodegradable pulp product.

5. Process according to claim 4, wherein the starting three-dimensional shaped biodegradable pulp product is a container comprising an annular compartment with a downwardly tapering outer wall of circular cross section and an upwardly tapering inner wall defining a central open channel through which a symmetry axis runs, wherein the annular compartment is closed at its lower end and open at its upper end.

6. Process according to claim 5, wherein in step (a) the outer wall surface of the outer wall, the inner wall surface of the annular compartment and the outer wall surface of the upwardly tapering inner wall is sprayed with the water-resistant compound while the three-dimensional shaped biodegradable pulp product rotates around the symmetry axis.

7. Process according to claim 6, wherein less or no water resistant compound is sprayed on the upwardly tapering inner wall as compared to the amount of water resistant compound sprayed on the downwardly tapering outer wall in terms of the amount of wax per surface area resulting in that the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall.

8. Process according to claim 5, wherein a different water-resistant compound is sprayed on the upwardly tapering inner wall as compared to the water-resistant compound sprayed on the downwardly tapering outer wall resulting in that the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall.

9. Process according to claim 1, wherein the 3D product and coated with a water-resistant compound is obtained by a process step wherein a three-dimensional biodegradable pulp product is present between at least two parts of a mould and wherein the water-resistant compound is supplied as a liquid to the surface of the starting three-dimensional biodegradable pulp product via channels as present in the mould parts which channels fluidly connect a source of the liquid water-resistant compound and the surface of the starting three-dimensional biodegradable pulp product.

10. Process according to claim 9, wherein the 3D product is a container comprising an annular compartment with a downwardly tapering outer wall of circular cross section and an upwardly tapering inner wall defining a central open channel through which a symmetry axis runs, wherein the annular compartment is closed at its lower end and open at its upper end.

11. Process according to claim 10, wherein less or no water resistant compound is supplied to the surface of the upwardly tapering inner wall as compared to the amount of water resistant compound supplied to the surface of the downwardly tapering outer wall in terms of the amount of wax per surface area resulting in that the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall.

12. Process according to claim 10, wherein a different water-resistant compound is supplied to the surface of the upwardly tapering inner wall as compared to the water-resistant compound supplied to the surface of the downwardly tapering outer wall resulting in that the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall.

13. A planting aid product comprising a container comprising an annular compartment for water composed of a biodegradable pulp with a downwardly tapering outer wall and an upwardly tapering inner wall defining a central open channel, where in use a plant is positioned, wherein the annular compartment is closed at its lower end and open at its upper end, wherein a circular lid closes the upper open end of the annular compartment and wherein the lid has a central opening which opening aligns with the central open channel of the container, and wherein the downwardly tapering outer wall and an upwardly tapering inner wall are coated by a water-resistant compound.

14. A planting aid product according to claim 13, wherein the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall, wherein the downwardly tapering outer wall is coated with a water-resistant compound and the upwardly tapering inner wall may be coated with a water-resistant compound and wherein the difference in water permeability of the inner and outer wall is at least in part a result of a difference in the content, quality and/or position of the water-resistant compound as coated on the inner and outer walls.

15. A planting aid product according to claim 13, wherein the water-resistant compound is a wax having a melting temperature of between 60 C. and 120 C.

16. A planting aid product according to claim 15, wherein the wax is a paraffinic wax and/or microwax.

17. A planting aid product according to claim 13, wherein the water permeability of the upwardly tapering inner wall is at least 0.05 litre/day as measured 5 days after the annular compartment is filled water to 95% of its vertical height.

18. A planting aid product according to claim 13, wherein no wick is present to transport water from the annular compartment to the plant in the central channel.

19. A planting aid product comprising: a container comprising an annular compartment for water composed of a biodegradable pulp with a downwardly tapering outer wall and an upwardly tapering inner wall defining a central open channel, where in use a plant is positioned, wherein the annular compartment is closed at its lower end and open at its upper end; and wherein a circular lid closes the upper open end of the annular compartment and wherein the lid has a central opening which opening aligns with the central open channel of the container; obtained by a process comprising: (a) spraying a water-resistant compound having a melting temperature of above 40 C. to coat a surface of a starting three-dimensional shaped biodegradable pulp product; (b) pressing the starting three-dimensional shaped biodegradable pulp product in a mould at a temperature above the melting temperature of the water-resistant compound; and (c) releasing the product from the mould and reducing the temperature to below the melting temperature of the water-resistant compound.

20. The planting aid product of claim 19, wherein the downwardly tapering outer wall is sprayed with a first water-resistant compound, and the upwardly tapering inner wall is sprayed with a different second water-resistant compound, resulting in that the upwardly tapering inner wall is more water permeable than the downwardly tapering outer wall.

Description

[0034] The invention will be illustrated by the following non-limiting Figures and Examples. The Figures show how the invention may be performed wherein the water-resistant compound is a wax. FIG. 1 is a starting three-dimensional shaped biodegradable pulp product (1) suited to make a planting apparatus. Shown is a container (2) comprising an annular compartment (3) for holding water. The annular compartment (3) is defined by a downwardly tapering outer wall (4) of circular cross section and an upwardly tapering inner wall (5) defining a central open channel (6) through which a symmetry axis (7) runs. The annular compartment (3) is closed at its lower end (8) and open at its upper end (9). The 3D product as obtained may be combined with a flat cover (not shown) to cover the open upper end (9) and a guiding cone (not shown) positioned in open channel (6) for guiding a plant as further described in WO2015/063243.

[0035] FIG. 2 shows how the inner walls (10) and the outer wall (11) of the annular compartment (3) of starting three-dimensional shaped biodegradable pulp product (1) of FIG. 1 is subjected to a wax spraying. The pulp product (1) is hereby fixed at with a fixing means (12) to a rotating axis (13) such that the entire product (1) rotates around the symmetry axis (7). Main supply (14) has two branches (15) and (16). These branches and also the spray guns suitably have heated mantles such to ensure that the wax remains liquid while it flows through these conduits. Branch (15) supplies wax to a spraying gun (17) which sprays wax on inner walls (10) of the annular compartment (3). Spraying gun (17) may also be a spraying module with more than one nozzle which may discharge wax at different rates. Branch (16) supplies wax to a spraying gun (18) which sprays wax on the outer wall (11) of the annular compartment (3). Because pulp product (1) rotates the spraying guns (17) and (18) can be positioned in one position with one spraying direction.

[0036] FIG. 3 shows the same pulp product (1) fixed with a fixing means (12) to a rotating axis (13). In this figure the outer wall surface (19) of the upwardly tapering inner wall (5) is sprayed using a spraying gun (20) with liquid droplets of wax while the biodegradable pulp product (1) rotates around the symmetry axis (7). The outer wall (21) of lower end (8) is sprayed by spraying gun (22). The liquid wax is supplied by main supply (23) connecting to two branches (24, 25). Branch (24) supplies wax to spraying gun (20) and branch (25) supplies wax to spraying gun (22). Because pulp product (1) rotates the spraying guns (20) and (22) can be positioned in one position with one spraying direction. Rotating axis (13) is preferably the same as in FIG. 2. In fact the spraying illustrated in FIGS. 2 and 3 may be performed one after the other in any sequence. Suitably the axis (13) with pulp product (1) fixed to its end is moved from the position as shown in FIG. 2 to the position as shown in FIG. 3 or from the position shown in FIG. 3 to the position shown in FIG. 2 wherein the spraying guns and supply conduits are not moved.

[0037] Alternatively, the spraying guns (20) and (21) illustrated in FIG. 3) may be moved towards the paper pulp product (1) as positioned as shown in FIG. 2) to spray all the outer surfaces of the paper pulp product (1) simultaneously. The reverse is also possible wherein the spraying guns (17,18) as illustrated in FIG. 2) are moved towards the paper pulp product (1) as positioned in FIG. 3). It is also understood that all surfaces may be sprayed simultaneously. Further the orientation of the rotating axis (13) may be any other orientation than the illustrated horizontal orientation. A suitable other orientation is vertical.

[0038] FIG. 4 shows a mould (26) having a mould part (27) having a surface (27a) shaped to receive the inner wall surface (28) of a cup shaped starting pulp product (29) and a mould part (30) having a surface (31) shaped to receive the outer wall surface (32) of the pulp product (29). Mould part (27) and mould part (30) provided with pulp product (29) are spaced away as will be the position when the mould part (27) is lowered into mould part (30). When the two mould parts (27) and (30) are pressed together the pulp product (29) will be sandwiched in between. Mould part (27) is provided with channels (33) fluidly connecting a source of liquid wax and the wall surface (27a) and the inner wall surface (28) of the cup shaped pulp product (29). When liquid wax is supplied to these channels the surface (28) will be provided with the liquid wax. Mould part (30) is also provided with channels (34) fluidly connecting a source of liquid wax and the wall surface (31) and the outer wall surface (32) of the cup shaped pulp product (29). When liquid wax is supplied to these channels the surface (32) will be provided with the liquid wax to form a coating of wax once the temperature is reduced to below the melting temperature of the wax.

[0039] The invention will be illustrated by the following non-limiting experiments.

EXAMPLE 1

[0040] A planting apparatus as shown in FIG. 1 was made from waste carton fibre pulp. The outer wall surface of the outer wall, the inner wall surface of the annular compartment and the outer wall surface of the inner wall is sprayed with liquid wax, which was a mixture of refined hydrocarbon waxes, having a melting point of 85. The temperature of the liquid wax as provided to the spraying gun was 120 C. The amount of wax sprayed on the surface of the planting apparatus was about 100 g/m.sup.2. The temperature was allowed to decrease to ambient temperatures such that the wax solidified. The planting apparatus thus obtained was placed in a mould at 125 C. for 15 seconds and wherein the two mould halves were pressed together at a moderate pressure of 0.25 MPa. The product was released from the mould and the temperature was reduced to ambient temperatures such that the wax solidified.

EXAMPLE 2

[0041] Example 1 was repeated except that the obtained waxed planting apparatus obtained in Example 1 was placed in a mould at 125 C. for 15 seconds and wherein the two mould halves were pressed together at a pressure of 1.5 MPa. The product was released from the mould and the temperature was reduced to ambient temperatures such that the wax solidified.

EXAMPLE 3

[0042] From the planting apparatuses as obtained in Examples 1-2 a circular cut out was obtained and fixed at the lower open end of a 5 cm diameter tube. The tubes were filed with a layer of 100 cm water and the decrease in water level was measured over time. The results are listed in Table 1. For comparison also a cut out of the starting planting apparatus was obtained, ie not treated with wax. This cut out was also fixed to a tube and filled with 100 cm water.

TABLE-US-00001 TABLE 1 Example 1 (with wax Example 2 Product - subjected Standard material and hot (with wax and hot to 100 cm water (no wax, with hot press (low press (high column pressure press) pressure) pressure) Water level after 10 56.0 100.0 100.0 minutes (cm) Water level after 60 <10 92.0 99.9 minutes (cm) Water level after 24.0 91.5 1440 minutes (cm)

[0043] The results in Table 1 show that when the pulp product is prepared according to the process of the invention a more water resistant product is obtained.