Preparation method of formaldehyde-free antibacterial veneered board based on redwood residues

Abstract

This invention discloses a method for preparing formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps, comprising the following steps: pretreatment of mahogany scraps; extraction of natural antibacterial extracts; preparation of antibacterial decorative paper; preparation of formaldehyde-free lignin adhesive; preparation of engineered wood panel substrate; and preparation of formaldehyde-free antibacterial decorative engineered wood panels. This invention achieves graded utilization of mahogany scraps. Fine sawdust is first used to extract antibacterial components, the residue is then used to prepare the adhesive, and coarse shavings are used as the substrate for the panels. The comprehensive utilization rate of the scraps reaches over 95%, far exceeding existing technologies, truly achieving "complete utilization" and significantly increasing the added value of mahogany scraps. This invention uses formaldehyde-free adhesives prepared from mahogany lignin, with no formaldehyde introduced throughout the entire production process. The formaldehyde release of the final product is far below the ENF standard, fundamentally solving the formaldehyde pollution problem.

Description

Technical Field

[0001] This invention belongs to the field of engineered wood product manufacturing technology, specifically relating to a method for preparing a formaldehyde-free antibacterial engineered wood product based on mahogany scraps. Background Technology

[0002] Rosewood, a traditional and precious high-grade timber in my country, is widely used in the processing of high-end furniture and handicrafts. However, the processing generates more than 30% of the raw materials, including sawdust, shavings, and scraps. Currently, the industry's utilization of rosewood scraps is relatively low-end, with most being used only as biomass fuel or raw materials for small handicrafts, or simply pressed into ordinary particleboard. The high-value active components in the scraps are not fully utilized, resulting in significant resource waste. According to data from the rosewood industry pilot project in Dongyang, Zhejiang, the current comprehensive utilization rate of rosewood scraps is only 79%, with a large amount of scraps still not achieving high-value transformation.

[0003] Furthermore, the traditional engineered wood products industry has long relied on urea-formaldehyde resin adhesives, which continuously release formaldehyde during use, causing indoor air pollution and harming human health. Although the industry has introduced products meeting low formaldehyde emission standards such as E0 and ENF, these standards cannot fundamentally eliminate the formaldehyde hazard. In addition, with increasing consumer demand for health products, antibacterial engineered wood products are becoming a market hotspot. However, most existing antibacterial engineered wood products achieve their antibacterial function by adding chemical antibacterial agents such as quaternary ammonium salts or nano-silver. This is not only costly but also poses safety risks such as chemical migration and secondary pollution, failing to meet consumers' demand for natural and safe products.

[0004] Studies have shown that rosewood heartwood is rich in polyphenols and condensed tannins, natural secondary metabolites. These substances possess excellent natural antibacterial and antioxidant properties, exhibiting significant inhibitory effects against common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus. Furthermore, rosewood contains a large amount of lignin, making it a high-quality raw material for preparing environmentally friendly adhesives. However, current technology lacks a solution for the complete component-level utilization of rosewood scraps.

[0005] Therefore, there is an urgent need for a method to prepare formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps, which combines the natural antibacterial components of mahogany with formaldehyde-free adhesive preparation technology to develop engineered wood panel products that combine formaldehyde-free environmental protection with natural antibacterial functions. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps, thereby solving the problems mentioned in the background section. The method provided by this invention for preparing formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps features graded and full-component utilization of mahogany scraps, fully exploiting the value of each component in the scraps.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps, comprising the following steps:

[0008] S1. Pre-treatment of rosewood scraps: Separate the rosewood scraps into two categories: wood chips and shavings;

[0009] S2. Extraction of natural antibacterial extract: Add solvent to the sawdust obtained in S1 and reflux to extract the natural antibacterial active ingredients from the sawdust. Filter and separate the natural antibacterial active ingredients to obtain the extract and extraction residue.

[0010] S3. Preparation of antibacterial decorative paper: The extract obtained in S2 is added to the impregnation solution in proportion to impregnate the decorative base paper. After drying, natural antibacterial decorative paper is obtained.

[0011] S4. Preparation of formaldehyde-free lignin adhesive: The extraction residue obtained in S2 is subjected to biological treatment to enrich high-purity modified lignin. Then, the lignin is alkalized and modified, and a formaldehyde-free crosslinking agent is added to react and formaldehyde-free lignin adhesive is prepared.

[0012] S5. Preparation of artificial board substrate: After drying the wood shavings obtained in S1, add the formaldehyde-free lignin adhesive prepared in S4, mix evenly, lay and pre-press, and then hot-press to form artificial board substrate.

[0013] S6. Preparation of formaldehyde-free antibacterial decorative artificial board: The natural antibacterial decorative paper prepared in S3 is attached to the surface of the artificial board substrate prepared in S5, and after hot pressing, formaldehyde-free antibacterial decorative artificial board is obtained.

[0014] In this invention, in step S1, the redwood scraps include wood chips and shavings, and the redwood scraps are screened using a 40-60 mesh sieve.

[0015] In this invention, in step S2, the solvent is an aqueous ethanol solution.

[0016] In this invention, in S2, the natural antibacterial active ingredients include polyphenols and condensed tannins.

[0017] In a further step of this invention, in S2, the extract is concentrated under reduced pressure to obtain a high-concentration antibacterial extract.

[0018] In this invention, in step S3, the mass ratio of the extract to the impregnation solution is 1:10.

[0019] In this invention, in step S4, after washing the extraction residue, brown rot fungal inoculum is introduced to utilize the selective degradation characteristics of brown rot fungi to decompose the cellulose and hemicellulose in the residue under mild conditions.

[0020] In this invention, in step S4, the alkalization modification solution is a 1 mol / L NaOH solution, and the pH is adjusted to 11.

[0021] In this invention, in step S4, the formaldehyde-free crosslinking agent is polyethylene glycol diglycidyl ether, and the mass ratio of the formaldehyde-free crosslinking agent to lignin is 3:20.

[0022] In this invention, in step S5, the wood shavings obtained in step S1 are thermally ground into mahogany fibers, which are then used to prepare medium-density fiberboard substrates.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention realizes the graded utilization of mahogany scraps. The fine wood chips are first used to extract antibacterial components, the residue is then used to prepare adhesives, and the coarse wood shavings are used as the substrate for boards. The comprehensive utilization rate of scraps reaches more than 95%, which is far higher than the existing technology. It truly achieves "making the most of everything" and greatly increases the added value of mahogany scraps.

[0025] 2. This invention uses a formaldehyde-free adhesive prepared from mahogany lignin. No formaldehyde is introduced during the entire production process, and the formaldehyde release of the final product is far below the ENF standard, thus solving the formaldehyde pollution problem at its source.

[0026] 3. The antibacterial components of this invention are derived from the natural polyphenols and tannins of rosewood itself. They are safe and non-toxic, with no risk of migration from chemical antibacterial agents. The antibacterial rate against Escherichia coli and Staphylococcus aureus reaches over 99%, and the antibacterial effect is long-lasting and stable.

[0027] 4. This invention uses waste mahogany scraps as the main raw material, eliminating the need to purchase expensive chemical antibacterial agents and synthetic adhesives. The production cost is reduced by more than 30% compared to traditional formaldehyde-free antibacterial decorative artificial boards, giving it a strong competitive edge in the market.

[0028] 5. The mechanical properties of the artificial board prepared by this invention meet the national standards. The static bending strength, internal bond strength and other indicators meet the requirements of GB / T 4897. At the same time, it has the functions of being formaldehyde-free and antibacterial, and can be widely used in indoor furniture, decoration and other fields. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the preparation process of the present invention.

[0030] Figure 2 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] In the description of this invention, the terms "upper," "lower," "right," and "left," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used merely for distinction in description and have no special meaning.

[0035] Example 1

[0036] Please see Figure 1 and Figure 2 This embodiment provides the following technical solution: a method for preparing formaldehyde-free antibacterial decorative artificial board based on mahogany scraps, comprising the following steps:

[0037] S1. Pre-treatment of waste materials: Use a 50-mesh sieve to screen the waste materials from the processing of Dalbergia latifolia to obtain 100kg of fine wood chips and 500kg of coarse wood shavings.

[0038] S2. Extraction of natural antibacterial extract: 100 kg of fine sawdust was added to 500 kg of 50% (v / v) ethanol aqueous solution, and refluxed at 60°C for 2 h. The extract and extraction residue were separated by filtration. The extract was concentrated under reduced pressure to a solid content of 20% to obtain the antibacterial extract. The total polyphenol content was found to be 12.5%, and the condensed tannin content was 8.2%.

[0039] S3. Preparation of antibacterial decorative paper: The above antibacterial extract was added to the decorative paper impregnation solution at a mass ratio of 10% and stirred evenly; the decorative base paper was immersed in the impregnation solution, and after removal, it was dried at 105℃ to a moisture content of 6% to obtain antibacterial decorative paper. Testing showed that the antibacterial rate of this decorative paper against Escherichia coli was 99.2%, and the antibacterial rate against Staphylococcus aureus was 99.5%.

[0040] S4. Preparation of formaldehyde-free lignin adhesive: After washing the extraction residue with water, inoculate it with 10% Gloeophyllum trabeum bacterial solution and culture it for 14 days at 28℃ and 65% relative humidity. After culture, the residue composition was tested: the cellulose content decreased from 42% to 8%, the hemicellulose content decreased from 22% to 5%, and the lignin content increased from 30% to 85%. The lignin residue was added to a 1mol / L NaOH solution, the pH was adjusted to 11, and 15% (by weight of lignin) of polyethylene glycol diglycidyl ether was added as a crosslinking agent. The reaction was carried out at 80℃ for 2 hours to obtain a formaldehyde-free lignin adhesive with a solid content of 45%.

[0041] S5. Preparation of artificial board substrate: Dry 500 kg of coarse wood shavings to a moisture content of 8%, add the above-mentioned formaldehyde-free lignin adhesive at a rate of 10% of the dried wood shavings mass, and mix at high speed for 5 min; after mixing, lay the substrate, pre-press at a pressure of 1 MPa for 5 min; then hot press at a temperature of 180℃, a pressure of 3 MPa, and a hot pressing time of 8 min to obtain an 18 mm thick particleboard substrate.

[0042] S6. Preparation of formaldehyde-free antibacterial decorative artificial board: The above-mentioned antibacterial decorative paper is laid on the surface of the above-mentioned particleboard substrate, and hot-pressed at 120℃ and 1.5MPa for 1 minute to obtain the final product.

[0043] Performance test results:

[0044] 1. Formaldehyde emission: Tested according to the climate chamber method of GB / T 17657-2022, the result was 0.006 mg / m³. 3 This is far below the ENF level (≤0.025 mg / m³). 3 Requirements;

[0045] 2. Antibacterial properties: Tested according to GB / T 21866-2025, the antibacterial rate against Escherichia coli is 99.1%, and the antibacterial rate against Staphylococcus aureus is 99.3%.

[0046] 3. Mechanical properties: static bending strength 18.5MPa, internal bond strength 0.85MPa, water absorption thickness expansion rate 6.2%, all of which meet the requirements of GB / T 4897-2015.

[0047] Example 2

[0048] The difference between this embodiment and embodiment 1 is that in S5, the coarse wood shavings are further hot-ground into mahogany fibers for the preparation of medium-density fiberboard, while the remaining steps are the same.

[0049] The final product's formaldehyde emission level is 0.008 mg / m³. 3 The antibacterial rate reaches 99.2%, and the mechanical properties meet the requirements of GB / T11718-2021.

[0050] In summary, this invention achieves graded utilization of rosewood scraps. Fine sawdust is first used to extract antibacterial components, the residue is then used to prepare adhesives, and coarse shavings are used as the substrate for boards. The comprehensive utilization rate of scraps reaches over 95%, far exceeding existing technologies, truly achieving "complete utilization" and significantly increasing the added value of rosewood scraps. This invention uses formaldehyde-free adhesives prepared from rosewood lignin, with no formaldehyde introduced throughout the entire production process. The formaldehyde release of the final product is far below the ENF standard, fundamentally solving the formaldehyde pollution problem. The antibacterial components of this invention come from the natural polyphenols and tannins of rosewood itself, are safe and non-toxic, and have no migration risk associated with chemical antibacterial agents. The antibacterial rate against Escherichia coli and Staphylococcus aureus both reach over 99%, with long-lasting and stable antibacterial effects. This invention uses waste rosewood scraps as the main raw material, eliminating the need to purchase expensive chemical antibacterial agents and synthetic adhesives. Production costs are reduced by more than 30% compared to traditional formaldehyde-free antibacterial decorative engineered wood panels, giving it strong market competitiveness. The mechanical properties of the engineered wood panels prepared by this invention meet national standards, and the static bending strength, internal bond strength and other indicators all meet the requirements of GB / T 4897. At the same time, they are formaldehyde-free and antibacterial, and can be widely used in indoor furniture, decoration and other fields.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing formaldehyde-free antibacterial decorative engineered wood panels based on mahogany scraps, characterized in that: Includes the following steps: S1. Pre-treatment of rosewood scraps: Separate the rosewood scraps into two categories: wood chips and shavings; S2. Extraction of natural antibacterial extract: Add solvent to the sawdust obtained in S1 and reflux to extract the natural antibacterial active ingredients from the sawdust. Filter and separate the natural antibacterial active ingredients to obtain the extract and extraction residue. S3. Preparation of antibacterial decorative paper: The extract obtained in S2 is added to the impregnation solution in proportion to impregnate the decorative base paper. After drying, natural antibacterial decorative paper is obtained. S4. Preparation of formaldehyde-free lignin adhesive: The extraction residue obtained in S2 is subjected to biological treatment to enrich high-purity modified lignin. Then, the lignin is alkalized and modified, and a formaldehyde-free crosslinking agent is added to react and formaldehyde-free lignin adhesive is prepared. S5. Preparation of artificial board substrate: After drying the wood shavings obtained in S1, add the formaldehyde-free lignin adhesive prepared in S4, mix evenly, lay and pre-press, and then hot-press to form artificial board substrate. S6. Preparation of formaldehyde-free antibacterial decorative artificial board: The natural antibacterial decorative paper prepared in S3 is attached to the surface of the artificial board substrate prepared in S5, and after hot pressing, formaldehyde-free antibacterial decorative artificial board is obtained.

2. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S1, the redwood scraps include wood chips and shavings, and the redwood scraps are screened using a 40-60 mesh sieve.

3. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In S2, the solvent is an aqueous solution of ethanol.

4. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In S2, the natural antibacterial active ingredients include polyphenols and condensed tannins.

5. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S2, the extract is concentrated under reduced pressure to obtain a high-concentration antibacterial extract.

6. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S3, the mass ratio of the extract to the impregnation solution is 1:

10.

7. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S4, after washing the extraction residue, brown rot fungus solution is introduced to decompose the cellulose and hemicellulose in the residue under mild conditions by utilizing the selective degradation characteristics of brown rot fungus.

8. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S4, the alkalization modification solution is a 1 mol / L NaOH solution, with the pH adjusted to 11.

9. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In S4, the formaldehyde-free crosslinking agent is polyethylene glycol diglycidyl ether, and the mass ratio of the formaldehyde-free crosslinking agent to lignin is 3:

20.

10. The method for preparing a formaldehyde-free antibacterial decorative artificial board based on mahogany scraps according to claim 1, characterized in that: In step S5, the wood shavings obtained in step S1 are thermally ground into mahogany fibers, which are then used to prepare medium-density fiberboard substrates.

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