Bagasse formaldehyde-free plate and preparation method thereof
High-performance formaldehyde-free boards were prepared by hot-pressing modified rosin resin with sugarcane bagasse, which solved the problems of formaldehyde release from traditional boards and insufficient utilization of sugarcane bagasse, achieving the effects of environmental protection and efficient resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAOGUAN COLLEGE
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-15
AI Technical Summary
Traditional engineered wood products continuously release free formaldehyde due to the use of formaldehyde-based adhesives, making it difficult to meet environmental standards. Furthermore, sugarcane bagasse, as a byproduct, is not effectively utilized, resulting in serious resource waste.
Using sugarcane bagasse as raw material, rosin resin modified with unsaturated polybasic acid is used as a formaldehyde-free adhesive, and formaldehyde-free boards are prepared by hot pressing process. This improves the interfacial compatibility between sugarcane bagasse and adhesive, and enhances stability and bonding strength.
The prepared formaldehyde-free boards have a density of 0.70-1.10 g/cm³, a static bending strength of ≥20 MPa, an internal bonding strength of ≥2.0 MPa, a water absorption thickness swelling rate of ≤8%, and a free formaldehyde release of ≤0.1 mg/L, meeting environmental protection standards and realizing the high-value utilization of resources and the application of green building materials.
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Figure CN122034091A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of engineered wood products manufacturing technology, specifically relating to a sugarcane bagasse formaldehyde-free board and its preparation method. Technical Background
[0002] Traditional urea-formaldehyde, phenol-formaldehyde, or melamine-modified formaldehyde adhesives used in the production of engineered wood products continue to release free formaldehyde, making it difficult to meet the highest ENF level (≤0.025mg / m³) requirement of GB / T 39600-2021 "Classification of Formaldehyde Emission from Engineered Wood Products". Developing truly "zero-formaldehyde" green boards has become an industry consensus.
[0003] Sugarcane bagasse is the largest byproduct of the sugar industry, with a global annual production exceeding 400 million tons. Except for a small amount used for fuel or animal feed, most is directly incinerated or landfilled, resulting in resource waste and carbon emissions. Sugarcane bagasse has a high cellulose content, low lignin content, and a well-developed porous structure, theoretically making it a high-quality plant fiber raw material that can replace wood in the manufacture of engineered wood products. However, the waxy and siliceous layers on the surface of sugarcane bagasse result in low surface activity and poor interfacial compatibility with conventional adhesives; using formaldehyde-based adhesives, on the other hand, fails to address the aldehyde release problem, contradicting the direction of green development.
[0004] Rosin possesses advantages such as a tricyclic phenanthrene skeleton, high carboxyl activity, renewability, and biodegradability; however, its direct use suffers from poor stability and a low softening point. Modifying rosin through the Diels-Alder addition reaction of unsaturated polybasic acids (acrylic acid, maleic acid, fumaric acid) introduces carboxylic acid side chains into the molecule and increases its molecular weight, thereby significantly improving its stability, softening point, and adhesive strength.
[0005] In view of the above reasons, this application proposes a method for preparing formaldehyde-free boards using sugarcane bagasse as raw material and polyacid-modified rosin resin as formaldehyde-free adhesive. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies by proposing a method for preparing formaldehyde-free boards using sugarcane bagasse as plant fiber raw material and polyacid-modified rosin resin as a formaldehyde-free adhesive via hot pressing. The invention also provides the board product directly obtained by this method. The board, measured according to GB / T 17657-2022, has a density of 0.70-1.10 g / cm³, static bending strength ≥20 MPa, internal bond strength ≥2.0 MPa, water absorption thickness swelling rate ≤8%, and free formaldehyde release ≤0.1 mg / L (desiccant method).
[0007] Therefore, the first technical solution provided by the present invention is as follows:
[0008] A method for preparing formaldehyde-free sugarcane bagasse board includes the following steps:
[0009] S1. Wash, dry, crush, and sieve the sugarcane bagasse;
[0010] S2. Under inert gas protection, rosin and unsaturated polybasic acid are mixed at a weight ratio of 100:10-30, and the mixture is heated to 180-250 ℃ and reacted for 1-3 h to obtain polybasic acid modified rosin resin.
[0011] S3. Mix the sugarcane bagasse obtained in step S1 with the polyacid modified rosin resin obtained in step S2 at a weight ratio of 100:5-15, spread the mixture in a hot press, and hot press for 5-30 minutes at a temperature of 160-240 ℃ and a pressure of 2-5 MPa. Cool and shape to obtain sugarcane bagasse formaldehyde-free board.
[0012] Furthermore, in the above-mentioned method for preparing formaldehyde-free sugarcane bagasse board, the sieve in step S1 has a pore size of 1-2 mm.
[0013] Furthermore, in the above-mentioned method for preparing formaldehyde-free sugarcane bagasse board, step S1 involves drying the material to a moisture content ≤10 wt%.
[0014] Furthermore, in the above-mentioned method for preparing formaldehyde-free sugarcane bagasse board, the unsaturated polyacid mentioned in step S2 is acrylic acid, maleic acid, fumaric acid, or a mixture thereof in any proportion.
[0015] Furthermore, in the above-mentioned method for preparing formaldehyde-free sugarcane bagasse board, the inert gas mentioned in step S2 is nitrogen.
[0016] The second technical solution of the present invention is to provide a sugarcane bagasse formaldehyde-free board, which is prepared by the method described in the first technical solution.
[0017] The sugarcane bagasse formaldehyde-free board provided by the present invention has a density of 0.70-1.10 g / cm³, static bending strength ≥20 MPa, internal bonding strength ≥2.0 MPa, water absorption thickness swelling rate ≤8%, and free formaldehyde release ≤0.1 mg / L (desiccator method) as measured according to GB / T 17657-2022.
[0018] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:
[0019] 1. This invention uses sugarcane bagasse as raw material, effectively utilizing a byproduct of the sugar industry, reducing resource waste and carbon emissions. It employs polyacid-modified rosin resin as a formaldehyde-free adhesive, avoiding the release of free formaldehyde found in traditional formaldehyde-based adhesives. The free formaldehyde release of the boards is ≤0.1 mg / L (GB / T17657-2022 desiccator method), far superior to boards made with traditional formaldehyde-based adhesives. This ensures the boards consistently meet ENF standards, satisfying environmental requirements. It achieves high-value utilization of agricultural and forestry waste and creates truly "zero-formaldehyde" green building materials, which can be widely used in furniture, decoration, and packaging.
[0020] 2. This invention improves the stability, softening point, and bonding strength of the adhesive by modifying rosin with unsaturated polybasic acids, enhances the interfacial compatibility between bagasse and the adhesive, and improves the overall performance of the board. The prepared formaldehyde-free board has a density of 0.70-1.10 g / cm³, static bending strength ≥20 MPa, internal bonding strength ≥2.0 MPa, and water absorption thickness swelling rate ≤8%, as measured according to GB / T 17657-2022.
[0021] 3. The technical solution provided by this invention directly utilizes the physical mixing of sugarcane bagasse and modified rosin resin. The preparation method is simple and feasible, requires no complex pretreatment, has high compatibility with existing hot pressing equipment, and is easy to industrialize. Attached Figure Description
[0022] Figure 1 These are images of the formaldehyde-free sugarcane bagasse boards prepared in Example 1 and Comparative Example 1.
[0023] Wherein: a is an appearance image of the sugarcane bagasse formaldehyde-free board prepared in Example 1; b is an appearance image of the sugarcane bagasse formaldehyde-free board prepared in Comparative Example 1.
[0024] Figure 2 These are SEM images of the surface and cross-section of the sugarcane bagasse formaldehyde-free boards prepared in Example 1 and Comparative Example 1;
[0025] Wherein: a is a surface SEM image of the sugarcane bagasse formaldehyde-free board prepared in Example 1; b is a surface SEM image of the sugarcane bagasse formaldehyde-free board prepared in Comparative Example 1; c is a cross-sectional SEM image of the sugarcane bagasse formaldehyde-free board prepared in Example 1; d is a cross-sectional SEM image of the sugarcane bagasse formaldehyde-free board prepared in Comparative Example 1.
[0026] Figure 3 The results are the static bending strength and internal bonding strength test results of the sugarcane bagasse formaldehyde-free boards prepared in Example 1 and Example 1.
[0027] Where: a is the static bending strength test result; b is the internal bonding strength test result. Detailed Implementation
[0028] The present invention will be further described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.
[0029] Example 1
[0030] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0031] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 2 mm sieve;
[0032] S2: 100 g of rosin and 20 g of maleic acid were stirred and reacted at 180 °C for 2 h under N2 protection to obtain modified rosin with an acid value of 280 mg KOH / g and a softening point of 110 °C.
[0033] S3: 100 g of sugarcane bagasse obtained in S1 and 10 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 200 ℃ and 3 MPa for 30 min, and then cooled to room temperature for shaping.
[0034] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.89 g / cm³, a static bending strength of 28 MPa, an internal bonding strength of 2.23 MPa, a water absorption thickness swelling rate of 6.5%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0035] Example 2
[0036] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0037] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 1 mm sieve;
[0038] S2: 100 g of rosin and 15 g of acrylic acid were stirred and reacted at 230 °C for 2 h under N2 protection to obtain modified rosin with an acid value of 210 mg KOH / g and a softening point of 110 °C.
[0039] S3: 100 g of sugarcane bagasse obtained in S1 and 15 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 160 ℃ and 1 MPa for 30 min, and then cooled to room temperature for shaping.
[0040] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.82 g / cm³, a static bending strength of 21 MPa, an internal bonding strength of 2.53 MPa, a water absorption thickness swelling rate of 3.3%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0041] Example 3
[0042] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0043] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 10 wt%, and crush it through a 1 mm sieve;
[0044] S2: 100 g of rosin and 25 g of fumaric acid were stirred and reacted at 250 °C for 2.5 h under N2 protection to obtain modified rosin with an acid value of 300 mg KOH / g and a softening point of 155 °C.
[0045] S3: 100 g of sugarcane bagasse obtained in S1 and 5 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 190 ℃ and 4 MPa for 20 min, and then cooled to room temperature for shaping.
[0046] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.95 g / cm³, a static bending strength of 25.5 MPa, an internal bonding strength of 2.85 MPa, a water absorption thickness swelling rate of 4.7%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0047] Example 4
[0048] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0049] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 2 mm sieve;
[0050] S2: 100 g of rosin, 15 g of acrylic acid, and 15 g of maleic acid were stirred and reacted at 210 °C for 2.5 h under N2 protection to obtain modified rosin with an acid value of 300 mg KOH / g and a softening point of 120 °C.
[0051] S3: 100 g of sugarcane bagasse obtained in S1 and 15 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 190 ℃ and 2 MPa for 20 min, and then cooled to room temperature for shaping.
[0052] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.88 g / cm³, a static bending strength of 25 MPa, a water absorption thickness swelling rate of 5.6%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0053] Example 5
[0054] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0055] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 10 wt%, and crush it through a 0.25 mm sieve;
[0056] S2: 100 g of rosin, 10 g of acrylic acid, 10 g of maleic acid, and 10 g of fumaric acid were stirred and reacted at 250 °C for 2.5 h under N2 protection to obtain modified rosin with an acid value of 320 mg KOH / g and a softening point of 120 °C.
[0057] S3: 100 g of sugarcane bagasse obtained in S1 and 10 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 190 ℃ and 5 MPa for 20 min, and then cooled to room temperature for shaping.
[0058] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.99 g / cm³, a static bending strength of 29 MPa, a water absorption thickness swelling rate of 3.5%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0059] Example 6
[0060] This embodiment provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0061] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 7 wt%, and crush it through a 1 mm sieve;
[0062] S2: 100 g of rosin and 30 g of maleic acid were stirred and reacted at 200 °C for 1 h under N2 protection to obtain modified rosin with an acid value of 350 mg KOH / g and a softening point of 130 °C.
[0063] S3: 100 g of sugarcane bagasse obtained in S1 and 10 g of modified rosin prepared in step S2 are mixed evenly, spread in a hot press, and hot-pressed at 240 ℃ and 5 MPa for 5 min, and then cooled to room temperature for shaping.
[0064] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.97 g / cm³, a static bending strength of 20 MPa, an internal bonding strength of 2.55 MPa, a water absorption thickness swelling rate of 2.5%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0065] Comparative Example 1
[0066] This comparative example provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0067] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 1 mm sieve;
[0068] S2: Mix 100 g of sugarcane bagasse and 10 g of rosin, spread them in a hot press, and hot press at 200 ℃ and 3 MPa for 30 min. Cool to room temperature to set.
[0069] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.90 g / cm³, a static bending strength of 13 MPa, an internal bonding strength of 1.33 MPa, a water absorption thickness swelling rate of 15.5%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0070] Comparative Example 2
[0071] This comparative example provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0072] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 1 mm sieve;
[0073] S2: Mix 100 g of sugarcane bagasse and 10 g of maleic acid, spread them in a hot press, and hot press at 200 ℃ and 3 MPa for 30 min. Cool to room temperature to set.
[0074] The sugarcane bagasse formaldehyde-free board prepared in this embodiment has a density of 0.88 g / cm³, a static bending strength of 10 MPa, an internal bonding strength of 0.55 MPa, a water absorption thickness swelling rate of 15.5%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0075] Comparative Example 3
[0076] This comparative example provides a method for preparing formaldehyde-free sugarcane bagasse boards, which includes the following steps in sequence:
[0077] S1: Clean the sugarcane bagasse, dry it at 105 ℃ to a moisture content of 8 wt%, and crush it through a 1 mm sieve;
[0078] S2: Spread 100 g of sugarcane bagasse into a hot press, press it at 200 ℃ and 3 MPa for 25 min, and cool it to room temperature to set, thus obtaining sugarcane bagasse board.
[0079] The sugarcane bagasse formaldehyde-free board prepared in this comparative example has a density of 0.88 g / cm³, a static bending strength of 7 MPa, an internal bonding strength of 0.42 MPa, a water absorption thickness swelling rate of 35.0%, and a free formaldehyde release of ≤0.1 mg / L (GB / T17657-2022 desiccator method).
[0080] 1. Surface macroscopic analysis
[0081] See the images of the sugarcane bagasse formaldehyde-free boards prepared in Example 1 and Comparative Example 1 for their appearance. Figure 1 .
[0082] in: Figure 1 In this image, 'a' is an appearance picture of the sugarcane bagasse formaldehyde-free board prepared in Example 1. Figure 1 Image b in the diagram shows the appearance of the sugarcane bagasse formaldehyde-free board prepared in Example 1. Figure 1 It can be seen that, under the same preparation conditions, the boards prepared using polyacid-modified rosin resin as an adhesive are darker in color than the boards prepared using unmodified rosin resin as an adhesive.
[0083] 2. Microstructure Analysis
[0084] Figure 2 These are SEM images of the surface and cross-section of the sugarcane bagasse formaldehyde-free boards prepared in Example 1 and Comparative Example 1. See also... Figure 2 ;in: Figure 2 In the diagram, 'a' is a surface SEM image of the sugarcane bagasse formaldehyde-free board prepared in Example 1; 'b' is a surface SEM image of the sugarcane bagasse formaldehyde-free board prepared in Comparative Example 1; 'c' is a cross-sectional SEM image of the sugarcane bagasse formaldehyde-free board prepared in Example 1; and 'd' is a cross-sectional SEM image of the sugarcane bagasse formaldehyde-free board prepared in Comparative Example 1. Figure 2 It can be seen that when using polyacid-modified rosin resin as an adhesive, there are fewer pores on the surface and interface of bagasse board, indicating that polyacid-modified rosin resin has better interfacial compatibility with bagasse fiber, which is beneficial to improving the strength and water resistance of the board.
[0085] 3. Static bending strength test
[0086] Test conditions: support span 100 mm, test plate size of Example 1 is 150×50×2.38 mm, test plate size of Comparative Example 1 is 150×50×2.45 mm; test conditions for internal bonding strength are: sample size is 50×50 mm, and hot melt adhesive is used to bond the sample and the clip together.
[0087] The test results of (a) static bending strength and (b) internal bonding strength of the sugarcane bagasse formaldehyde-free boards prepared in Example 1 and Example 1 are as follows: Figure 3 .Depend on Figure 3 It can be seen that, under the same preparation conditions, the board prepared in Example 1 has better static bending strength and internal bonding strength than that of Comparative Example 1. This invention demonstrates that the method for preparing formaldehyde-free boards using sugarcane bagasse as plant fiber raw material and polyacid-modified rosin resin as formaldehyde-free adhesive via hot pressing controls the free formaldehyde release to ≤0.1 mg / L (GB / T17657-2022 desiccator method), while significantly improving the static bending strength, internal bonding strength, and water resistance of the sugarcane bagasse board.
[0088] In summary, the formaldehyde-free boards prepared in Examples 1-6 of this application, measured according to GB / T 17657-2022, have a density of 0.70-1.10 g / cm³, static bending strength ≥20 MPa, internal bonding strength ≥0.70 MPa, water absorption thickness swelling rate ≤8%, and free formaldehyde release ≤0.1 mg / L (desiccator method). In contrast, in the comparative examples, the adhesives were unmodified rosin, maleic acid, or no adhesive was added, resulting in a decrease in static bending strength and internal bonding strength, and an increase in water absorption thickness swelling rate in the prepared bagasse boards.
Claims
1. A method for preparing formaldehyde-free sugarcane bagasse board, characterized in that, Includes the following steps: S1. Wash, dry, crush, and sieve the sugarcane bagasse; S2. Under inert gas protection, rosin and unsaturated polybasic acid are mixed at a weight ratio of 100:10-30, and the mixture is heated to 180-250 ℃ and reacted for 1-3 h to obtain polybasic acid modified rosin resin. S3. Mix the sugarcane bagasse obtained in step S1 with the polyacid modified rosin resin obtained in step S2 at a weight ratio of 100:5-15, spread the mixture in a hot press, and hot press for 5-30 minutes at a temperature of 160-240 ℃ and a pressure of 2-5 MPa. Cool and shape the mixture to obtain sugarcane bagasse formaldehyde-free board.
2. The method for preparing formaldehyde-free sugarcane bagasse board according to claim 1, characterized in that, The aperture of the sieve described in step S1 is 1-2 mm.
3. The method for preparing formaldehyde-free sugarcane bagasse board according to claim 1, characterized in that, The drying described in step S1 is drying to a moisture content ≤10 wt%.
4. The method for preparing formaldehyde-free sugarcane bagasse board according to claim 1, characterized in that, The unsaturated polyacid mentioned in step S2 is acrylic acid, maleic acid, fumaric acid, or a mixture thereof in any proportion.
5. The method for preparing formaldehyde-free sugarcane bagasse board according to claim 1, characterized in that, The inert gas mentioned in step S2 is nitrogen.
6. A formaldehyde-free sugarcane bagasse board, characterized in that, Prepared using the method described in any one of claims 1-5.