Bamboo leaf artificial board and preparation method thereof

Abstract

The invention provides a bamboo leaf artificial board and a preparation method thereof, and belongs to the technical field of artificial boards, the artificial board is prepared by selecting bamboo leaf crushed aggregates, the size of the bamboo leaf crushed aggregates is less than 14 meshes, and the glue application amount in the artificial board accounts for 11-15% of the total mass of the bamboo leaf crushed aggregates; the preparation method comprises the following steps: step 1, preparing materials; step 2, crushing the materials; step 3, blending a phenolic resin adhesive into a dilute solution with the concentration of 20-25%, slowly pouring the dilute solution into the crushed bamboo leaves, and continuously stirring to uniformly mix the resin and the crushed bamboo leaves; step 4, drying; step 5, assembling blanks; step 6, hot pressing; step 7, unloading the plate; the high-performance bamboo leaf artificial board is prepared by taking bamboo leaves as a main raw material and high-permeability phenolic resin as an adhesive through a'cold-in and cold-out 'hot pressing process.

Description

Technical Field

[0001] The invention relates to the technical field of artificial boards, and in particular to a bamboo leaf artificial board and a preparation method thereof. Background Art

[0002] my country is rich in bamboo resources and has a huge bamboo industry system. At present, the main bamboo industry uses bamboo stalks, while bamboo tips, bamboo branches, bamboo leaves and other logging residues have not been reasonably utilized. Bamboo leaves are one of the main components of bamboo logging residues. Except for a small amount used to extract the contents, most of them are abandoned in the mountains or used as fuel. This not only causes a waste of bamboo resources, but also poses a serious threat to the ecological environment.

[0003] Processing bamboo leaves into artificial boards is one of the effective ways to solve the above problems. There are patents that use bamboo leaves as surface materials for artificial boards, but the amount used is small, and there are problems such as poor gluing quality, low mechanical properties, and insufficient water resistance. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to address the deficiencies in the prior art and provide a bamboo leaf artificial board and a preparation method thereof, using bamboo leaves as the main raw material, and adopting a highly permeable phenolic resin as an adhesive, and a "cold in and cold out" hot pressing process to prepare high-performance bamboo leaf artificial boards.

[0005] Technical solution: The bamboo leaf artificial board described in the present invention is prepared by selecting bamboo leaf chips, and the size of the bamboo leaf chips is below 14 meshes, which means that the diameter of the particles is less than or equal to the aperture size corresponding to the mesh number of the sieve.

[0006] Furthermore, the amount of glue applied in the artificial board accounts for 11-15% of the total mass of the bamboo leaf chips.

[0007] A method for preparing a bamboo leaf artificial board comprises the following steps:

[0008] Step 1: Prepare the ingredients

[0009] The freshly picked bamboo leaves are dried to control the moisture content below 5%; the dried bamboo leaves are easier to cut and crush.

[0010] Step 2: Crushing

[0011] The dried bamboo leaves are mechanically crushed and sieved to retain bamboo leaf fragments below 14 mesh; the surface area of ​​the crushed bamboo leaves is increased, which is convenient for subsequent gluing.

[0012] Step 3: Gluing

[0013] Prepare a phenolic resin adhesive into a dilute solution with a concentration of 20-25%, slowly pour it into the bamboo leaf scraps, and stir continuously to make the resin and the bamboo leaf scraps mix evenly;

[0014] Step 4: Drying

[0015] The bamboo leaf chips after sizing are ventilated and dried at 25-70°C, and the moisture content is controlled within the range of 13±2%.

[0016] Step 5: Embryo

[0017] Weigh a set amount of bamboo leaf scraps and spread them evenly in the mold to form a slab;

[0018] Step 6: Heat pressing

[0019] The slab is placed in a hot press for hot pressing;

[0020] Step 7: Remove the board

[0021] After the hot pressing is completed, the hot press is cooled to 65°C or below to release the pressure and obtain the bamboo leaf artificial board.

[0022] Furthermore, in step 3, the sizing amount of the bamboo leaf chips ranges from 11 to 15%.

[0023] Furthermore, the density of the bamboo leaf fragments in step 5 is 0.8 to 1.2 g / cm 3 .

[0024] Furthermore, release paper is laid on both the upper and lower surfaces of the slab in contact with the hot press.

[0025] Furthermore, in step 6, the hot pressing is specifically as follows: first preheat the hot press to 145° C., then put the slab together with the backing plate into the hot press, and the hot pressing parameters are a pressure of 0.4 to 0.8 MPa and a holding time of 1.0 to 1.2 min / mm.

[0026] Furthermore, the specific method of spreading the material in step 5 is: using paper pieces to divide the mold into a group of grids, and then dividing the scraps equally into each grid to ensure the uniformity of the scraps.

[0027] Beneficial effects: Compared with the prior art, the advantages of the present invention are:

[0028] (1) The present invention processes bamboo leaves, one of the residues from bamboo processing, into artificial boards, which can turn waste into treasure and reduce the waste of bamboo resources and environmental pollution;

[0029] (2) Since the gluing performance of bamboo leaves is relatively poor, the present invention uses a high-permeability low-molecular-weight phenolic resin as an adhesive, which can significantly improve the problem of poor calibration performance and improve the gluing performance of bamboo leaf artificial boards;

[0030] (3) The present invention mechanically crushes bamboo leaves to less than 14 meshes to obtain a high-performance artificial board; in particular, the bamboo leaf crushed material is less than 14 meshes, the amount of glue applied is more than 11%, and the board density is 1.0g / cm 3 When the parameters are above 0.05, the artificial board prepared has higher bending resistance and water resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the preparation process of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0033] Example 1

[0034] A bamboo leaf artificial board, the artificial board is prepared by selecting bamboo leaf scraps, the size of the bamboo leaf scraps is less than 14 meshes, the amount of glue applied in the artificial board accounts for 11-15% of the total mass of the bamboo leaf scraps, and the board density is 0.8-1.2g / cm 3 .

[0035] like Figure 1 The method for preparing a bamboo leaf artificial board shown comprises the following steps:

[0036] Step 1: Prepare the ingredients

[0037] The freshly picked bamboo leaves are dried to control the moisture content below 5%.

[0038] Step 2: Crushing

[0039] The dried bamboo leaves are mechanically crushed and sieved to retain bamboo leaf fragments below 14 meshes.

[0040] Step 3: Gluing

[0041] The phenolic resin adhesive is prepared into a dilute solution with a concentration of 20-25%, and slowly poured into the bamboo leaf chips, and stirred continuously to make the resin and the bamboo leaf chips evenly mixed; the amount of glue applied to the bamboo leaf chips ranges from 11 to 15%.

[0042] Step 4: Drying

[0043] The bamboo leaf chips after sizing are ventilated and dried at 25-70°C, and the moisture content is controlled within the range of 13±2%.

[0044] Step 5: Embryo

[0045] In this embodiment, in order to achieve 0.8g / cm 3 Density, mold size is 300×300×3mm 3, the mass of bamboo leaf scraps is 226g, first divide the mold into 25 grids, weigh an appropriate amount of bamboo leaf scraps, and evenly spread the scraps in each grid to form a slab. The phenolic resin glue used in this embodiment is a thermosetting phenolic resin adhesive purchased from Taier Adhesive (Guangdong) Co., Ltd. (solid content is 46.71% (2h / 120℃), viscosity is 41cps (25℃), pH=10.50, free phenol <1%, free aldehyde <0.19%).

[0046] Step 6: Heat pressing

[0047] The slab is placed in a hot press for hot pressing; first preheat the hot press to 145°C, and then place the slab together with the pad into the hot press. The hot pressing parameters are a pressure of 0.4-0.8MPa and a holding time of 1.0-1.2min / mm. The holding time is customized according to the thickness of the plate. For example, if the plate thickness is 3mm, the holding time is (1.0-1.2)x3=3-3.6min.

[0048] Step 7: Remove the board

[0049] After the hot pressing is completed, the hot press is cooled to 65°C or below to release the pressure and obtain the bamboo leaf artificial board.

[0050] Experimental Example 1 Effect of the size of bamboo leaf fragments on bending resistance and water resistance

[0051] (1) Test method

[0052] The sizes of bamboo leaf fragments were set as above 6 mesh, 6-14 mesh, 14-20 mesh and below 20 mesh, the sizing amount was 11%, and the density was 0.8 g / cm2 using the "cold in and cold out" process. 3 of the specimen.

[0053] The specific sample preparation steps are as follows: ① Material preparation: Spread the bamboo leaves loosely on an iron plate, and send them into a 105℃ forced air drying oven for drying for 30 minutes; then take them out and crush them, screen out bamboo leaf fragments above 6 mesh, 6-14 mesh, 14-20 mesh and below 20 mesh, and seal them for later use. ② Gluing: Weigh a certain mass of phenolic resin glue, add a certain amount of distilled water, and dilute it into a glue solution with a solid content of 25%; then slowly add it to a certain amount of bamboo leaf fragments, and stir continuously until the two are evenly mixed; ③ Drying: Spread the bamboo leaf fragments after gluing in a well-ventilated room for air drying, and the final moisture content is about 13%. ④ Assembly: Weigh a certain amount of bamboo leaf fragments and spread them on a 300×300mm 2in the mold. To prevent the glue from adhering to the pad, release paper is placed on the top and bottom of the slab. In order to evenly spread the bamboo leaf fragments in the mold, use cardboard to divide the mold into 25 grids, and then divide the weighed bamboo leaf fragments into 25 portions, and spread them in each grid. ⑤ Hot pressing: first preheat the hot press to 145°C, and then put the slab together with the pad into the hot press; close the press to a pressure of 0.4MPa, and then keep the heat and pressure for 3 minutes; turn off the heating and maintain the pressure. ⑥ Unloading the plate: When the press cools naturally to 65°C, unload the pressure; the specifications of the produced plate are 300×300×3mm 3 , and keep it in an indoor environment for 7 days to balance its moisture content.

[0054] (2) Performance testing

[0055] According to the national standard GB / T 17657-2022 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels", the three-point bending method is used to determine the static bending strength (MOR) and elastic modulus (MOE) of particleboard. The sample size is 150×50×3mm 3 ; Test 24h water absorption and thickness expansion rate, the specimen size is 50×50×3mm 3 .

[0056] (3) Test results

[0057] The bending resistance and water resistance of the boards at different bamboo leaf chip sizes are shown in Table 1. As shown in Table 1, the MOR and MOE of the bamboo leaf artificial board are in the range of 6-14 MPa and 1-2 GPa, respectively. As the size of the bamboo leaf chips decreases, the MOR and MOE gradually increase; compared with the boards with a size of more than 14 mesh, the performance of the boards with a size of less than 14 mesh is significantly improved.

[0058] Table 1 Effect of bamboo leaf fragment size on bending resistance and water resistance

[0059]

[0060] Note: The data in brackets are standard deviations.

[0061] In addition, the water resistance of bamboo leaf panels below 14 mesh is also significantly improved. As shown in Table 1, the 24h water absorption rate and water absorption thickness expansion rate of bamboo leaf panels are in the range of 67% to 35% and 35% to 17%, respectively. As the size of bamboo leaf chips decreases, both tend to decrease. When the size of bamboo leaf chips is less than 14 mesh, the water absorption rate and thickness expansion rate of the board are significantly reduced.

[0062] In summary, bamboo leaf fragments with a size below 14 mesh are more suitable for processing artificial boards, and have higher physical and mechanical properties.

[0063] Test Example 2 Effect of Glue Application Amount on Physical and Mechanical Properties of Sheets

[0064] (1) The test method is the same as 1, the size of the bamboo leaf fragments is less than 20 mesh, and the density is set to 1.00 g / cm 3 , the sizing amount was set as a variable, which were 9%, 11%, 13% and 15% respectively.

[0065] (2) The test methods for bending resistance and water resistance are the same as 1.

[0066] (3) Test results:

[0067] The bending resistance and water resistance of the board at different sizing amounts are shown in Table 1. With the increase of sizing amount, MOR first increases and then decreases, while MOE gradually decreases; when the sizing amount is 13%, MOR and MOE reach their maximum values.

[0068] Table 2 Effect of glue application amount on bending resistance and water resistance

[0069]

[0070]

[0071] Note: The data in brackets are standard deviations.

[0072] In addition, with the increase of the amount of glue applied, the water absorption rate and thickness expansion rate of the board gradually decreased. When the amount of glue applied was higher than 11%, the water absorption rate and thickness expansion rate of the two boards were close, and higher than those with less than 11%.

[0073] In conclusion, when the sizing agent content is within the range of 13% to 15%, the bamboo leaf artificial board has higher physical and mechanical properties.

[0074] Test Example 3 Effect of Density on Physical and Mechanical Properties of Plates

[0075] (1) The test method is the same as 1. The size of the bamboo leaf fragments is less than 20 mesh, the glue dosage is 13%, and the density is set as a variable, which are 0.9, 1.0, 1.1 and 1.2 g / cm 3 .

[0076] (2) The test methods for bending resistance and water resistance are the same as 1.

[0077] (3) Test results:

[0078] The MOR and MOE of bamboo leaf panels at different densities are shown in Table 3. As the density increases, the MOR shows an increasing trend, while the MOE increases first and then decreases. 3 When , MOR and MOE are both high.

[0079] Table 3 Effect of density on bending resistance and water resistance

[0080]

[0081] Note: The data in brackets are standard deviations.

[0082] In addition, as the density increases, the water absorption rate and thickness expansion rate of bamboo leaf artificial board gradually decrease. 3 When processed, bamboo leaf artificial board has lower water absorption rate and thickness expansion rate, and higher water resistance.

[0083] In summary, the density is 1.0g / cm 3 As mentioned above, bamboo leaf artificial board has higher physical and mechanical properties.

[0084] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A bamboo leaf artificial board, characterized in that: The artificial board is prepared from bamboo leaf chips, and the size of the bamboo leaf chips is less than 14 meshes.

2. The bamboo leaf artificial board according to claim 1, characterized in that: The amount of glue applied in the artificial board accounts for 11-15% of the total mass of the bamboo leaf fragments.

3. A method for preparing a bamboo leaf artificial board, characterized in that The steps include: Step 1: Prepare the ingredients Dry the fresh bamboo leaves picked and control the moisture content below 5%; Step 2: Crushing Mechanically crush and sieve the dried bamboo leaves, and retain bamboo leaf fragments below 14 meshes; Step 3: Gluing Prepare a phenolic resin adhesive into a dilute solution with a concentration of 20-25%, slowly pour it into the bamboo leaf scraps, and stir continuously to mix the resin and the bamboo leaf scraps evenly; Step 4: Drying The bamboo leaf chips after sizing are ventilated and dried at 25-70°C, and the moisture content is controlled within the range of 13±2%. Step 5: Embryo Weigh the set bamboo leaf fragments and spread them evenly in the mold to form a slab. Control the density of the slab to 0.8-1.2 g / cm 3 ; Step 6: Heat pressing The slab is placed in a hot press for hot pressing; Step 7: Remove the board After the hot pressing is completed, the hot press is cooled to 65°C or below to release the pressure and obtain the bamboo leaf artificial board.

4. The method for preparing a bamboo leaf artificial board according to claim 3, characterized in that: In the step 3, the glue application amount of the bamboo leaf fragments is in the range of 11-15%.

5. The method for preparing a bamboo leaf artificial board according to claim 3, characterized in that: In step 5, the density of the slab is controlled to be 0.8-1.2 g / cm 3 .

6. The method for preparing a bamboo leaf artificial board according to claim 3, characterized in that: Release paper is laid on both the upper and lower surfaces of the slab in contact with the hot press.

7. The method for preparing a bamboo leaf artificial board according to claim 3, characterized in that: In step 6, the hot pressing is specifically as follows: first preheat the hot press to 145° C., then put the slab together with the backing plate into the hot press, and the hot pressing parameters are a pressure of 0.4 to 0.8 MPa and a holding time of 1.0 to 1.2 min / mm.

8. The method for preparing a bamboo leaf artificial board according to claim 3, characterized in that: The specific method of laying the material in step 5 is: using paper pieces to divide the mold into a group of grids, and then dividing the scraps equally into each grid.

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