Method for the Production of Artificial Wood Board

Abstract

The present invention relates to a method for the production of artificial wood board. More specifically, present invention relates to a method for the production of highly durable, low cost, environmental friendly artificial wood board. Furthermore the present invention relates to artificial wood boards obtainable by the methods of present invention.

Claims

1. A method for the production of artificial wood board, wherein the method comprises the following steps; a) milling of lignin containing plant material to obtain a milled mixture; b) conditioning of said milled mixture to obtain an equilibrium moisture content of between 12% to 25%, preferably of between 16% to 25%; c) homogenising of said conditioned milled mixture; d) cold-pressing of the homogenous mixture obtained in step c to obtain a brittle board; e) hot-pressing of said brittle board to reach a density of between 1.2 to 1.4 g/cm.sup.3 to obtain an artificial wood board.

2. A method according to claim 1, wherein said lignin containing plant material comprises particles with a particle size of less than 5 mm, preferably less than 2.5 mm, more preferably less than 2 mm.

3. The method according to claim 1, wherein said lignin containing plant material comprises coconut husk pith.

4. The method according to claim 1, wherein said lignin containing plant material comprises fresh plant material of less than 6 months old.

5. The method according to claim 1, wherein said lignin containing plant material comprises a moisture content of between 12% to 25%, preferably of between 16% to 25%.

6. The method according to claim 1, wherein said equilibrium moisture content is adjusted by the addition of water to said milled mixture to obtain said equilibrium moisture content.

7. The method according to claim 1, wherein step e is followed by conditioning said artificial wood board under static pressure for at least 24 hours to obtain a form-stable artificial wood board.

8. The method according to claim 1, wherein in step d said homogenous mixture is cold pressed to obtain a brittle board with a thickness of at least 1:3, preferably at least 1:4, more preferably at least 1:5, most preferably at least 1:6, when compared to the thickness of the material before cold pressing.

9. The method according to claim 1, wherein step e is performed in total in 1 to 4 minutes per 1 mm layer thickness of said brittle board, preferably 1 to 3 minutes per 1 mm layer thickness of said brittle board, more preferably 1.5 to 2 minutes per 1 mm layer thickness of said brittle board.

10. The method according to claim 1, wherein step e is performed at a temperature of between 140 C. to 220 C., preferably 150 C. to 200 C., more preferably 160 C. to 180 C.

11. The method according to claim 1, wherein step e is performed at a pressure of 120 to 170 bars, preferably 130 to 160 bars, most preferably 140 to 150 bars.

12. The method according to claim 1, wherein said conditioned milled mixture obtained in step b is mixed with other wood like materials and/or additives and/or polymers and/or cement-based compositions.

13. An artificial wood board obtainable by a method according to claim 1.

14. The artificial wood board according to claim 13, wherein said artificial wood board has a bending strength of at least 46 N/mm.sup.2, preferably at least 47 N/mm.sup.2.

15. The artificial wood board according to claim 13, wherein said artificial wood board has a moisture content of between 12% to 25%, preferably of between 16% to 25%.

16. The artificial wood board according to claim 13, wherein said artificial wood board has a thickness swelling of at most 13%, preferably at most 12%, more preferably at most 10%, most preferably at most 9% due to moist absorption after immersion in a aqueous solution for 24 hours according to European Standard EN 317.

17. The artificial wood board according to claim 13, wherein said artificial wood board has an internal bond strength of at least 1.8 N/mm.sup.2, preferably at least 2.2 N/mm.sup.2, more preferably at least 2.5 N/mm.sup.2.

18. The artificial wood board according to claim 13, wherein said artificial wood board comprises at least 25% to 50% v/v of coir dust.

19. The artificial wood board according to claim 13, wherein said artificial wood board comprises a composition comprising lignin containing plant material mixed with other wood like materials and/or additives and/or polymers and/or cement-based compositions.

Description

[0034] The present invention will be further detailed in the following examples

Example 1 Milling

[0035] Fresh coconut husk (less than 6 months old) has been imported from Indonesia. This has been stored in plastic bags in a conditioned room at 95% relative humidity (RH) and 28 C. in order to maintain the freshness of the husk. Later, circa 2 kg of coconut husk has been sawed in smaller parts and milled with FRITSCH model 15.302/694 in three different steps (no sieve, 10 mm sieve, 2 mm sieve). The final result is a mix of fiber and dust sieved at 2 mm.

Example 2 Conditioning and Moisture Content

[0036] The milled coconut coir has been conditioned in two different climate rooms: RH 50% at 24 C. and RH 65% at 20 C. for a period of between 5 to 12 days, depending on the moisture content of the milled coconut coir. Next, the moisture content was determined weighing the wet sample, drying in oven at 103 C. for at least 18 hours and finally weighing the dry sample following the formula:

[00001]$\mathrm{EMC}=\frac{\mathrm{mw}-\mathrm{md}}{\mathrm{md}}*100$

Wherein mw and md are respectively wet weight and dry weight.

Example 3 Production Wood Boards

[0037] The process comprises the steps:

[0038] 1. Coir conditioning

[0039] 2. Pre-pressing

[0040] 3. Hot-Pressing

[0041] 4. Conditioning under static pressure

[0042] 5. Trimming

[0043] 6. Board conditioning

1. Coir conditioning

[0044] This step is performed until the target equilibrium moisture content (EMC) has been reached.

2. Pre-pressing

[0045] Conditioned coir is loaded in a mold in order to reach a final density of 1.35 g/cm.sup.3. After having spread uniformly the coir, the mold has been pressed with 0.15 Tons/cm.sup.2 for 1 minute. In this case 69.8 g of coir is loaded in a steel mold of 1015 cm at 22.5 Tons for 1 minute.

3. Hot pressing

[0046] The result of the pre-pressing step is a brittle board called Prepack. The produced Prepacks were put between two aluminum plates 1.6 mm thick and pressed at 170 C. at 22.5 Tons (0,15Tons/cm.sup.2) for 4 minutes, including the heating up time. Then, the sample was cooled down inside the press till an internal temperature of 50 C. was measured with a thermocouple.

4. First conditioning under static pressure

[0047] The produced boards were conditioned at room temperature under a mass overnight.

5 Trimming

[0048] Trimming of the sample was performed after the first conditioning and before the second conditioning step in order to eliminate the dry-non cured-material.

6. Second Conditioning

[0049] The trimmed samples were conditioned at 65% RH and 20 C. until the mass did not change more than 0.01% according to the European Standard EN 310, e.g. to obtain a form-stable product. The samples were put on supports with a mass on top of them in order to keep the flatness.

Example 4 Determine Physical-Mechanical Proprieties of the Artificial Wood Board

[0050] Samples where cut after having reached a stable weigh in two squares 5050 mm and one strip of 28 mm. The samples produced were tested according the European Standard EN 622-2. This standard includes all the tests required to compare the artificial wood board with High Density Fiberboards (HDF) also called Hardboards (HB). List of the specific tests is provided below.

TABLE-US-00001 TABLE 1 Tests according to European Standards performed on the artificial wood board. Test name European Standard Determination of the density EN 322 Swelling thickness after immersion in water 24 h EN 317 Bending strength, flexural modulus EN 310 Internal Bond EN 319 Internal Bond after boil test EN 319 - EN1087-1

Results

[0051] 11 samples of artificial wood board were tested according to European Standards as set out above. Samples 1 to 5, 10 and 11 have a moisture content of 16.4%, and samples 6 to 9 have a moisture content of 12%.

Density

[0052] Density measurements have been made according with European standard EN 322 in duplicate on samples 1, 2, 3, 4, 8, 9, 10 and 11.

TABLE-US-00002 TABLE 3 Density measurements of artificial wood board samples weight height width thickness density sample (g) (mm) (mm) (mm) (g/cm.sup.3) 1.1 10.71 50.26 49.98 3.03 1.41 1.2 11.38 50.29 50.33 3.22 1.40 2.1 10.92 50.41 50.40 3.06 1.40 2.2 10.97 50.52 50.35 3.10 1.39 3.1 10.87 50.42 50.44 3.08 1.39 3.2 10.78 50.39 50.29 3.05 1.40 4.1 10.94 50.51 50.37 3.11 1.38 4.2 10.51 50.28 50.79 2.98 1.38 8.1 10.65 50.23 50.21 3.036 1.39 8.2 11.04 50.26 50.23 3.113 1.40 9.1 10.7 50.33 50.14 3.03 1.40 9.2 10.89 50.03 50.29 3.08 1.41 10.1 10.54 48.05 49.23 3.19 1.40 10.2 10.58 48.92 49.34 3.13 1.40 11.1 10.23 48.80 49.69 3.01 1.40 11.2 10.31 48.99 49.86 3.00 1.41 Average 10.863 50.328 50.318 3.073 1.40
Bending strength and flexural modulus

[0053] Bending strength and flexural modulus test has been made on all the samples according European standard EN310.

TABLE-US-00003 TABLE 4 Bending strength and flexural modulus of artificial wood board samples Bending Strength Flexural modulus Sample (N/mm.sup.2) (N/mm.sup.2) 1.3 46.28 4156.44 2.3 46.37 4221.63 3.3 47.99 4217.41 4.3 45.68 6944.53 5.1 46.83 4409.03 5.2 46.22 4419.26 Average 16.4% 46.56 4728.05 6.1 47.85 4660.25 6.2 45.39 4601.92 6.3 46.54 4590.80 7.1 47.29 4387.31 7.2 38.89 3625.64 7.3 41.30 3757.09 8.3 39.26 3790.51 9.3 46.99 4233.77 Average 12% 44.19 4205.91
Internal bond and internal bond after boiling test

[0054] Internal bond and internal bond after boiling test was performed on samples 1 to 4 according to European Standard EN319 and EN1087-1.

TABLE-US-00004 TABLE 5 Internal bond and internal bond after boil test of artificial wood board samples. Strength Sample after Strength Sample (N/mm.sup.2) boil test (N/mm.sup.2) 1.1 2.61 1.2 2.03 2.1 1.69 2.2 1.64 3.1 2.15 3.2 1.21 4.1 3.96 4.2 1.59 Average 2.60 1.61
Swelling in thickness after immersion in water 24h

[0055] This test has been made on the following samples according the European Standard EN317.

TABLE-US-00005 TABLE 6 Swelling in thickness after immersion in water measurements weight Height Width Thickness Swelling Sample (g) (mm) (mm) (mm) (%) 8.1 11.77 50.88 50.94 3.413 12.4% 8.2 12.10 50.87 50.81 3.505 12.6% 9.1 11.86 50.98 50.82 3.417 12.8% 9.2 11.96 50.76 50.91 3.465 12.5% 10.1 11.49 48.64 49.84 3.485 9.1% 10.2 11.48 49.49 50.02 3.482 11.1% 11.1 11.24 49.51 50.24 3.382 12.5% 11.2 11.32 49.68 50.56 3.382 12.6%