Preparation method of non-grain oil-based formaldehyde-free bamboo particle board

Abstract

The invention discloses a preparation method of a non-grain oil-based formaldehyde-free bamboo particle board. The non-grain oil-based bamboo particle board is prepared from a non-grain oil-based adhesive and bamboo particles. The non-grain oil-based adhesive is prepared from the following raw materials: an oil refining byproduct, glycidyl methacrylate, epoxy resin, a reinforcing agent, triethylene diamine and tert-butyl peroxybenzoate. The preparation method comprises the following steps: S1, preparing the non-grain oil-based adhesive; s2, uniformly spraying glue; s3, mechanically mixing; and S4, hot press molding. According to the method, the non-grain and non-oil waste grease mixture is used as the raw material to prepare the adhesive, the bamboo processing waste is glued to prepare the bamboo particle board, and high-value utilization of the bamboo processing waste and grease refining by-products is achieved; the prepared adhesive has the characteristics of high bio-based content, excellent bonding strength, good weather resistance, no formaldehyde, low cost, reproducibility and the like; the prepared bamboo particle board is free of formaldehyde release and has excellent mechanical performance, water resistance and high temperature resistance.

Description

Technical Field

[0001] This invention patent relates to the field of engineered wood products, specifically a method for preparing a non-grain oil-based formaldehyde-free bamboo chip board. Background Technology

[0002] The bamboo processing industry generates a massive amount of waste, typically producing 0.3-0.5 tons of waste per ton of bamboo pulp, including bamboo shavings and residues, mainly from processing by-products, trimming waste, and debris. The overall utilization rate of bamboo is generally low, usually less than 30%, meaning that approximately 70% of bamboo may become waste. Meanwhile, the oil refining industry also faces the challenge of high-value utilization of by-products. Oil refining generates large quantities of waste oil mixtures, including acidified oil, soapstock, deodorized distillates, and oil residue, with annual production reaching millions of tons. Currently, most of these waste oil mixtures are used only as low-cost fuels or industrial additives, and some even cause environmental risks such as water and soil pollution due to improper disposal. Their rich content of fatty acids, glycerides, and other natural active ingredients is not fully utilized, indicating significant potential for value extraction. How to transform them into high-value-added products has become one of the key issues for the green transformation of the oil processing industry. However, in the current production of bamboo chipboard, traditional formaldehyde-containing adhesives do not meet environmental protection requirements, while bio-based adhesives have defects such as low bio-based content, insufficient bonding strength, and poor weather resistance. They also fail to effectively combine the resource utilization of bamboo waste with the utilization of oil refining by-products, thus failing to achieve synergistic value-added of both wastes. Summary of the Invention

[0003] To solve the above-mentioned technical problems, this invention provides the following technical solution: a method for preparing a non-grain oil-based formaldehyde-free bamboo chip board, wherein the non-grain oil-based bamboo chip board is prepared from a non-grain oil-based adhesive and bamboo chips; the raw materials of the non-grain oil-based adhesive are oil refining by-products, glycidyl methacrylate, epoxy resin, reinforcing agent, triethylenediamine, and tert-butyl peroxide; Furthermore, the oil refining byproduct is a mixture of waste oils obtained during the process of refining vegetable oils into biodiesel; Furthermore, the oil refining byproduct is a mixture of waste oils obtained during the refining of biodiesel from vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil. The preparation method of the non-grain oil-based formaldehyde-free bamboo chipboard includes the following steps: S1: Preparation of non-grain oil-based adhesive: The by-products of oil refining, glycidyl methacrylate and triethylenediamine are initially stirred, then cooled, epoxy resin and reinforcing agent are added and stirred a second time, and after cooling, tert-butyl peroxide is added and stirred a third time to obtain the non-grain oil-based adhesive. S2: Uniform spraying of adhesive: The non-grain oil-based adhesive prepared in step S1 is uniformly sprayed onto the surface of the dried bamboo chips to obtain mixed adhesive bamboo chips; S3: Mechanical mixing: The mixed bamboo fragments obtained in step S2 are mechanically mixed to obtain a homogeneous mixture; S4: Hot pressing: The uniform mixture obtained in step S3 is hot pressed on a flat vulcanizing machine using a three-stage hot pressing process to obtain a non-grain oil-based formaldehyde-free bamboo chip board.

[0004] Oil refining byproducts are essentially biomass derivatives rich in long-chain fatty acids, glycerides, and polar groups (hydroxyl -OH, carboxyl -COOH), belonging to renewable natural resources. This characteristic allows them to replace a large amount of petrochemical-based raw materials in traditional adhesives, endowing materials with low-carbon and renewable green attributes from the raw material level. Oil refining byproducts and glycidyl methacrylate (GMA, containing epoxy groups) undergo an epoxy ring-opening reaction under the action of triethylenediamine catalyst (carboxyl groups react with epoxy groups to form ester bonds, and hydroxyl groups react with epoxy groups to form ether bonds), initially forming a covalently linked prepolymer. The subsequently added epoxy resin further reacts with the residual active groups in the prepolymer, while the reinforcing agent participates in the free radical polymerization initiated by tert-butyl peroxide through double bonds, ultimately forming a three-dimensional interpenetrating cross-linked network. This network structure has strong intermolecular forces and is not easily destroyed by external forces, providing a high-strength foundation for adhesion. Long-chain fatty acids or glycerides, byproducts of oil refining, have a certain degree of lubricity, which can reduce the viscosity of the system after the components are mixed, making it easier for the components to disperse evenly during mechanical stirring and avoiding incomplete local reactions.

[0005] Furthermore, the oil refining byproducts account for 50% to 58%, the glycidyl methacrylate accounts for 22% to 30%, the epoxy resin accounts for 10% to 20%, the reinforcing agent accounts for 10% to 20%, the triethylenediamine accounts for 2% to 5%, and the tert-butyl peroxide accounts for 2% to 5%.

[0006] Oil refining byproducts account for 50%–58% of adhesive formulations, making them the most abundant component and directly forming the basic framework of the adhesive. Essentially, they are biomass derivatives rich in long-chain fatty acids, glycerides, and polar groups (hydroxyl -OH, carboxyl -COOH), belonging to renewable natural resources. This characteristic allows them to replace a large amount of petrochemical-based raw materials in traditional adhesives, significantly increasing the bio-based content of the adhesive and endowing the material with low-carbon, renewable, and green attributes from the raw material level. The 22%–30% proportion of glycidyl methacrylate covers the active sites of oil byproducts, avoiding weak oil-epoxy interface bonding due to insufficient glycidyl methacrylate, or excessive amounts leading to too much flexible component and insufficient adhesive rigidity. Simultaneously, the high bio-based properties form hydrogen bonds with the hydroxyl groups of cellulose and hemicellulose on the surface of bamboo chips, significantly improving the processability of the adhesive and the interfacial bonding with bamboo chips, reducing the risk of interfacial debonding, and enhancing the mechanical properties of the board. 50%~58% of the oil refining byproducts contain long-chain fatty acids that repel water molecules, providing natural hydrophobicity, while 10%~20% of epoxy resin forms a dense cross-linked barrier, blocking the water penetration path. The appropriate ratio of the two reduces the water absorption rate of the adhesive, thereby improving the internal bonding strength of bamboo chipboard in humid environments.

[0007] Furthermore, the oil refining byproducts are derived from waste oil mixtures obtained during the refining of biodiesel from vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil.

[0008] The production of biodiesel generates a large amount of waste mixture containing free fatty acids, glycerol, and gum. If this waste is discharged directly, it will increase the burden on wastewater treatment due to its high chemical oxygen demand. However, using it as a raw material for adhesives is equivalent to providing a waste resource outlet for the biodiesel industry, realizing a dual cycle of waste utilization and significantly reducing solid / liquid waste emissions.

[0009] Furthermore, the epoxy resin is either epoxy resin E51 or epoxy resin E44.

[0010] E51 and E44 have non-polar to weakly polar structures, exhibiting far better compatibility with oil refining byproducts (long-chain fatty acids, glycerides, non-polar) and GMA (weakly polar) than with more polar epoxy resins. After mixing, they do not exhibit stratification, precipitation, or particle agglomeration, forming a homogeneous and stable adhesive system. This avoids localized adhesive shortages or aggregates in the board caused by uneven adhesive distribution in steps S2 and S3, thus improving the density uniformity of the board and consequently increasing its strength.

[0011] Furthermore, the reinforcing agent is any one of unsaturated polyester, vinyl resin, and bisphenol A glyceride.

[0012] Unsaturated polyester, vinyl resin, and bisphenol A glyceride are all free of harmful components such as formaldehyde and benzene compounds, and no volatile organic compounds (VOCs) are released during the curing process of unsaturated polyester and vinyl resin.

[0013] Furthermore, the initial stirring in step S1 is mechanical stirring at 110℃~130℃ for 2~3 hours; the secondary stirring is mechanical stirring at 50℃~70℃ for 0.5~2 hours; and the tertiary stirring is stirring at room temperature for 20~40 minutes.

[0014] Initial stirring promotes a deep reaction between oil byproducts and GMA. At 110℃~130℃, the epoxy groups of GMA rapidly open under the action of triethylenediamine, undergoing etherification or esterification reactions with the active groups of the oil. A reaction time of 2~3 hours allows 80%~90% of the active groups to participate in the reaction, forming a flexible framework of long-chain oil-GMA epoxy modification. Secondary stirring protects the stability of the epoxy resin and reinforcing agent, while ensuring uniform dispersion of components and avoiding local aggregation. Epoxy resin is prone to self-polymerization at high temperatures, and the double bonds of the reinforcing agent may also react prematurely at high temperatures. A medium-temperature environment of 50℃~70℃ can suppress these side reactions, while ensuring a slow reaction between the epoxy groups of the epoxy resin and the residual active groups of the modified oil-GMA, forming a preliminary interpenetrating network of flexible oil chains and rigid epoxy chains. Tertiary stirring, followed by the addition of tert-butyl benzoate and stirring at room temperature, plays a crucial role in preventing premature decomposition of tert-butyl benzoate, ensuring its uniform dispersion and precise function during the hot-pressing stage.

[0015] Furthermore, the dried bamboo chips mentioned in step S2 are obtained by drying at 100℃~103℃ for 2~4 hours.

[0016] Furthermore, the three-stage hot pressing process in step S4 is as follows: pre-press at 6MPa for 60s, then increase the pressure to 15MPa for 15min, and then depressurize to 3MPa and hold for 60s.

[0017] Even after mechanical mixing, bamboo chips still contain a significant amount of air within gaps. A pre-compression pressure of 6 MPa can quickly compress these gaps, allowing the bamboo chips to initially form a tight contact. 60 seconds is sufficient to expel 80%–90% of the air, preventing incomplete air removal and the formation of voids at the edges of the board, which reduces internal bond strength. Bamboo chips have high hardness; directly applying high pressure can cause them to slide and shift under pressure, leading to localized accumulation or sparse distribution, resulting in uneven board density. The 6 MPa pre-compression temporarily fixes the position of the chips through friction, laying the foundation for uniform stress during the subsequent high-pressure stage. Simultaneously, the 6 MPa pressure… Force can promote the slow penetration of adhesive into the gaps between the fragments, but will not cause the adhesive to be squeezed out in large quantities due to excessive pressure; the pressure of 15MPa is close to the compressive strength limit of the bamboo fiber, which improves the bonding strength, but will not cause the fiber to break due to excessive pressure, thus reducing the strength of the board; after the main hot pressing, the board generates strong internal stress due to high pressure, the fiber compresses and deforms, and the adhesive cross-links and shrinks. Direct and complete pressure release will release the stress instantly, causing the edge of the board to warp. Low pressure holding for 60 seconds and slow pressure release first maintain the shape of the board by low pressure, while allowing the fiber and adhesive to slowly rebound within the elastic range, reducing internal stress.

[0018] The beneficial effects achieved by this invention are as follows: (1) This invention uses the waste oil mixture obtained in the process of refining biodiesel from non-grain and oil vegetable oils as raw material to prepare adhesive, and uses the prepared adhesive to bond the waste generated from bamboo processing to prepare bamboo chip board, thereby reducing the amount of solid / liquid waste discharge and pollution, while realizing the high-value utilization of bamboo processing waste and oil refining by-products; (2) The adhesive prepared by this invention has high bio-based content, excellent bonding strength and good weather resistance, and also has the characteristics of being formaldehyde-free, low cost and renewable; (3) The bamboo chip board prepared by this invention has no formaldehyde release and has excellent mechanical properties, water resistance and high temperature resistance, which fully meet the board performance requirements stipulated by national standards. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments.

[0020] The byproducts of oil refining were derived from waste oil mixtures obtained during the refining of biodiesel from vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil; epoxy resin E51, epoxy resin E44, unsaturated polyester, and vinyl resin were purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.; glycidyl methacrylate, bisphenol A glyceryl ester, triethylenediamine, and tert-butyl peroxide were purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Example

[0021] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 20 g of vinyl resin were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0022] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0023] 54 g of oil refining byproducts, 26 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 20 g of vinyl resin were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0024] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0025] 58 g of oil refining byproducts, 22 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 20 g of vinyl resin were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0026] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0027] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E44 and 20 g of vinyl resin were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0028] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0029] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, 10 g of epoxy resin E51 and 20 g of vinyl resin were added and mechanically stirred for 1 h, cooled to room temperature and then tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0030] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0031] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 10 g of vinyl resin were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0032] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0033] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 20 g of unsaturated polyester were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0034] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board. Example

[0035] 50 g of oil refining byproducts, 30 g of glycidyl methacrylate and 1 g of triethylenediamine were mechanically stirred at 120°C for 2.5 h, cooled to 60°C, and 20 g of epoxy resin E51 and 20 g of bisphenol A glyceryl ester were added and mechanically stirred for 1 h. After cooling to room temperature, tert-butyl peroxide was added and mechanically stirred for 30 min to obtain the adhesive.

[0036] Bamboo scraps were dried at 103℃ for 3 hours, and the resulting adhesive was evenly sprayed onto their surface. The mixture was mechanically stirred for 10 minutes, and then pre-pressed at 6 MPa for 60 seconds on a flat vulcanizing machine at 140℃. The pressure was then increased to 15 MPa and hot-pressed for 15 minutes. Finally, the pressure was released to 3 MPa and held for 60 seconds to form a non-grain oil-based formaldehyde-free bamboo scrap board.

[0037] According to the national standard GB / T 17657-2013, various properties of the prepared bamboo chipboard were tested: the internal bond strength test used 50mm×50mm square specimens, which were bonded with hot melt adhesive and the internal bonding performance of the board was evaluated on a universal tensile testing machine, with each group repeated 6 times; the water absorption swelling rate test used specimens of the same size, which were soaked in water at 25℃ for 24 hours and the thickness change was measured, with each group repeated 3 times; the static bending strength and elastic modulus were determined by the three-point bending method, using 150mm×50mm long strip specimens, with each group also repeated 3 times.

[0038] Table 1 shows the physical and mechanical property test results of eight formaldehyde-free bamboo chipboard examples. Their internal bond strength ranged from 0.86 to 2.60 MPa, with Example 1 showing the best performance. The static bending strength ranged from 16.87 to 23.12 MPa, with Example 4 exhibiting the most outstanding performance in this indicator. The elastic modulus ranged from 2440 to 3300 MPa, again with Example 4 showing the highest. The water absorption swelling rate increased from 14.33% to 17.02%, with Example 3 showing the lowest water absorption. All data showed varying degrees of coefficient of variation, indicating that different formulation processes affect the stability of the board's performance. However, the non-grain oil-based formaldehyde-free bamboo chipboard prepared by the method proposed in this invention exhibits excellent mechanical properties (internal bond strength, static bending strength, elastic modulus), water resistance, and high-temperature resistance, and also has the advantage of no formaldehyde release.

[0039] Table 1 Physical and mechanical properties of formaldehyde-free bamboo chipboard Example Internal bond strength / MPa Static bending strength / MPa Elastic modulus / MPa Water absorption swelling rate / % 1 2.60 ± 0.28 18.49 ± 3.93 2590 ± 520 14.54 ± 0.52 2 2.36 ± 0.14 18.54 ± 5.14 2710 ± 420 14.87 ± 1.21 3 2.48 ± 0.06 18.33 ± 6.12 2680 ± 360 14.33 ± 1.44 4 1.41 ± 0.27 23.12 ± 7.84 3300 ± 790 15.32 ± 2.40 5 0.92 ± 0.08 18.89 ± 2.59 2610 ± 400 15.97 ± 0.96 6 1.91 ± 0.11 18.18 ± 2.05 2620 ± 280 16.49 ± 1.64 7 0.86 ± 0.22 16.87 ± 3.44 2440 ± 410 17.02 ± 2.03 8 2.32 ± 0.10 17.97 ± 2.74 2660 ± 340 15.96 ± 3.01 The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a non-grain oil-based formaldehyde-free bamboo chipboard, characterized in that, The non-grain oil-based bamboo chip board is prepared from non-grain oil-based adhesive and bamboo chips; the raw materials of the non-grain oil-based adhesive are oil refining by-products, glycidyl methacrylate, epoxy resin, reinforcing agent, triethylenediamine, and tert-butyl peroxide; the preparation method includes the following steps: S1: Preparation of non-grain oil-based adhesive: The by-products of oil refining, glycidyl methacrylate and triethylenediamine are initially stirred, then cooled, epoxy resin and reinforcing agent are added and stirred a second time, and after cooling, tert-butyl peroxide is added and stirred a third time to obtain the non-grain oil-based adhesive. S2: Uniform spraying of adhesive: The non-grain oil-based adhesive prepared in step S1 is uniformly sprayed onto the surface of the dried bamboo chips to obtain mixed adhesive bamboo chips; S3: Mechanical mixing: The mixed bamboo fragments obtained in step S2 are mechanically mixed to obtain a homogeneous mixture; S4: Hot pressing: The uniform mixture obtained in step S3 is hot pressed on a flat vulcanizing machine using a three-stage hot pressing process to obtain a non-grain oil-based formaldehyde-free bamboo chip board.

2. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The oil refining byproducts account for 50% to 58%, the glycidyl methacrylate accounts for 22% to 30%, the epoxy resin accounts for 10% to 20%, the reinforcing agent accounts for 10% to 20%, the triethylenediamine accounts for 2% to 5%, and the tert-butyl peroxide accounts for 2% to 5%.

3. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The oil refining byproducts are derived from waste oil mixtures obtained during the refining of biodiesel from vegetable oils such as waste cooking oil, palm oil, soybean oil, castor oil, and corn oil.

4. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The epoxy resin is either epoxy resin E51 or epoxy resin E44.

5. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The reinforcing agent is any one of unsaturated polyester, vinyl resin, and bisphenol A glyceride.

6. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The initial stirring in step S1 is mechanical stirring at 110℃~130℃ for 2~3 hours; the secondary stirring is mechanical stirring at 50℃~70℃ for 0.5~2 hours; and the tertiary stirring is stirring at room temperature for 20~40 minutes.

7. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The dried bamboo chips mentioned in step S2 are obtained by drying at 100℃~103℃ for 2~4 hours.

8. The method for preparing non-grain oil-based formaldehyde-free bamboo chipboard according to claim 1, characterized in that: The three-stage hot pressing process in step S4 is as follows: pre-press at 6MPa for 60s, then increase the pressure to 15MPa for 15min, and then depressurize to 3MPa and hold for 60s.