Process for modifying wood by using high-stability composite nano material

Abstract

The invention relates to a process for modifying wood through a high-stability composite nano material, and belongs to the technical field of wood modification. The technology for modifying the wood through the high-stability composite nanometer material comprises the following steps that the wood is cleaned and dried, and pretreated wood is obtained; the preparation method comprises the following steps: dissolving a functional monomer, hydroxyl acrylamide and allyl glycidyl ether in absolute ethyl alcohol, adding a titanate coupling agent and an initiator, and stirring and mixing to obtain modified liquid; and the pretreated wood is soaked in the modified liquid for dipping treatment, the wood is taken out, deionized water is sprayed to the surface of the wood, aging and heating heat preservation treatment are conducted, vacuum drying is conducted till the weight is constant, and the wood is obtained. According to the method, a nano titanium dioxide material can be effectively combined with a wood matrix, and meanwhile, the hydrophobicity, the antibacterial property and the compressive strength of the wood are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wood modification and relates to a process for modifying wood with a high-stability composite nano material. Background Art

[0002] As a renewable and environmentally friendly natural material, wood has a wide range of applications in construction, furniture, decoration, packaging and other fields. However, natural wood itself has many performance defects, which seriously limit its scope of use and lifespan. On the one hand, wood is a porous hydrophilic material. Its rich cellulose, hemicellulose and lignin structure contains a large number of hydroxyl groups, which makes the wood very susceptible to water absorption and moisture, which in turn causes problems such as deformation and cracking, shortening its service life. On the other hand, the humid environment provides ideal living conditions for microorganisms (such as fungi and bacteria), making wood susceptible to decay, mildew and insect damage, which not only reduces the mechanical properties of wood, but also poses a potential threat to human health.

[0003] To address these issues, traditional wood modification technologies include physical treatment (such as high-temperature heat treatment and microwave treatment), chemical treatment (such as preservative impregnation and resin infusion), and biological treatment (such as enzyme treatment). While physical treatment can improve the dimensional stability of wood to a certain extent, it has limited effects on its mechanical and antimicrobial properties.

[0004] In recent years, nanomaterial modification technology has provided a new direction for wood modification due to its unique size effects and excellent performance. Nano-titanium dioxide exhibits excellent photocatalytic antibacterial and reinforcing properties, while polymeric materials can impart hydrophobicity and mechanical reinforcement to wood. However, current nanomaterial-based wood modification processes still face several technical bottlenecks, such as poor dispersion of nanoparticles in wood, weak interfacial bonding with the wood matrix, and difficulty in achieving efficient, synergistic improvements in multiple properties during the modification process. Summary of the Invention

[0005] The purpose of the present invention is to provide a process for modifying wood with high-stability composite nanomaterials. The present invention can effectively combine nano-titanium dioxide materials with wood matrix, while significantly improving the hydrophobicity, antibacterial properties and compressive strength of wood.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A process for modifying wood with a high-stability composite nanomaterial comprises the following steps:

[0008] Step 1: Clean and dry the wood to obtain pretreated wood;

[0009] Step 2: dissolving the functional monomer, hydroxyacrylamide and allyl glycidyl ether in anhydrous ethanol, adding a titanate coupling agent and an initiator, and stirring and mixing to obtain a modified liquid;

[0010] Step 3: soak the pretreated wood in the modified liquid for impregnation treatment, take out the wood and spray deionized water on its surface, age it, heat and keep it warm, and vacuum dry it to constant weight to obtain the product.

[0011] As a preferred technical solution of the present invention, in step one, the cleaning is to wash the wood surface with deionized water, and the drying is to dry at 85°C for 4-6 hours and at 100°C to constant weight, to clean and remove surface microorganisms and impurities. The drying treatment directly reduces the moisture content of the wood and the moisture in the pores, laying the foundation for subsequent hydrophobic modification.

[0012] As a preferred technical solution of the present invention, in step 2, the stirring and mixing is performed at a rotation speed of 400-600 rpm for 15-20 minutes.

[0013] As a preferred technical solution of the present invention, in step 2, the mass ratio of the functional monomer, hydroxyacrylamide, allyl glycidyl ether, titanate coupling agent, initiator and anhydrous ethanol is 6-8:2.0-2.5:1.4-1.8:1.2-1.5:0.20-0.22:30-40, and the initiator is initiator AIBN.

[0014] As a preferred technical solution of the present invention, in step three, the modified liquid penetrates into the pores of the wood, and the hydrophobic polymer formed by polymerization covers the surface and internal channels of the wood, hindering water penetration. The titanium dioxide nanoparticles generated by the hydrolysis of the titanate coupling agent can form a rough surface, compressive strength and toughness. The titanium dioxide nanoparticles are combined with the hydrophobic polymer to further enhance the hydrophobicity through the lotus leaf effect. The titanium dioxide nanomaterial can generate photocatalytic free radicals under light, destroy the bacterial cell membrane, and achieve an antibacterial effect.

[0015] In step three, the volume ratio of the pretreated wood to the modified liquid is 1:6.

[0016] As a preferred technical solution of the present invention, in step three, the impregnation treatment is vacuum impregnation at a pressure of -1 MPa for 40-60 minutes, followed by pressure impregnation at a pressure of 1 MPa for 2.0-3.0 hours.

[0017] As a preferred technical solution of the present invention, in step three, the spraying amount of the deionized water is 0.4-0.5 times the weight gain of the pretreated wood after the impregnation treatment.

[0018] As a preferred technical solution of the present invention, in step three, the aging is aging at room temperature for 24-30 hours, the heating and heat preservation treatment is heat preservation at 80°C for 6-8 hours and then at 110-120°C for 1.0-1.5 hours, and the vacuum drying is vacuum drying to constant weight.

[0019] As a preferred technical solution of the present invention, in step 2, the method for preparing the functional monomer comprises the following steps:

[0020] Under an inert atmosphere, acrolein, acetic acid and anhydrous ethanol are mixed, o-chloroaniline is added, heated and stirred, rotary evaporated, and freeze-dried to obtain the product.

[0021] As a preferred technical solution of the present invention, in the preparation of the functional monomer, the inert atmosphere is any one of a nitrogen or argon atmosphere, the heating and stirring is 60-65°C and 200-400 rpm for 4-6 hours, and the mass ratio of acrolein, o-chloroaniline, acetic acid and anhydrous ethanol is 2.8-4.0:2.0-2.5:0.06-0.08:20-25.

[0022] Beneficial effects of the present invention:

[0023] The present invention achieves simultaneous improvement of the hydrophobicity, antibacterial properties and compressive strength of wood through the synergistic modification of functional monomers, specific chemical reagents and wood, and utilizes titanate coupling agents for hydrolysis to generate nano-titanium dioxide, thereby overcoming the limitations of the single nature of traditional modification technologies and achieving both environmental friendliness and high efficiency. DETAILED DESCRIPTION

[0024] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0025] The wood used in this embodiment and the comparative example is 10-year-old fast-growing poplar wood, and the titanate coupling agent is isopropyl titanate triisostearate.

[0026] Example 1

[0027] A process for modifying wood with a high-stability composite nanomaterial comprises the following steps:

[0028] Step 1: cleaning the wood surface with deionized water, then drying at 85° C. for 4 h and at 100° C. to constant weight to obtain pretreated wood;

[0029] Step 2: dissolving the functional monomer, N-hydroxyacrylamide and allyl glycidyl ether in anhydrous ethanol, adding a titanate coupling agent and an initiator AIBN, and stirring at 400 rpm for 15 minutes to obtain a modified liquid; wherein the mass ratio of the functional monomer, N-hydroxyacrylamide, allyl glycidyl ether, titanate coupling agent, initiator AIBN and anhydrous ethanol is 6:2.0:1.4:1.2:0.20:30;

[0030] Step 3: Immerse the pretreated wood in the modifying liquid, vacuum impregnate it at a pressure of -1 MPa for 40 minutes, and then pressurize it at a pressure of 1 MPa for 2.0 hours. Take out the wood and spray deionized water on its surface. Age it at room temperature for 24 hours, keep it warm at 80°C for 6 hours, and then keep it warm at 110°C for 1.0 hour. Vacuum dry it to constant weight to obtain the product; wherein the amount of deionized water sprayed is 0.4 times the weight gain of the pretreated wood after impregnation treatment, and the volume ratio of the pretreated wood to the modifying liquid is 1:6.

[0031] The preparation method of the functional monomer comprises the following steps:

[0032] Under a nitrogen inert atmosphere, acrolein, acetic acid and anhydrous ethanol were mixed, o-chloroaniline was added, and the mixture was stirred at 60°C and 200 rpm for 4 hours. The solvent was removed by rotary evaporation, and the mixture was freeze-dried to obtain the product; wherein the mass ratio of acrolein, o-chloroaniline, acetic acid and anhydrous ethanol was 2.8:2.0:0.06:20.

[0033] Example 2

[0034] A process for modifying wood with a high-stability composite nanomaterial comprises the following steps:

[0035] Step 1: cleaning the wood surface with deionized water, then drying at 85° C. for 5 h and at 100° C. to constant weight to obtain pretreated wood;

[0036] Step 2: dissolving the functional monomer, N-hydroxyacrylamide and allyl glycidyl ether in anhydrous ethanol, adding a titanate coupling agent and an initiator AIBN, and stirring at 500 rpm for 18 minutes to obtain a modified liquid; wherein the mass ratio of the functional monomer, N-hydroxyacrylamide, allyl glycidyl ether, titanate coupling agent, initiator AIBN and anhydrous ethanol is 7:2.2:1.6:1.4:0.21:35;

[0037] Step 3: Immerse the pretreated wood in the modifying liquid, vacuum impregnate it at a pressure of -1 MPa for 50 minutes, and then pressurize it at a pressure of 1 MPa for 2.5 hours. Take out the wood and spray deionized water on its surface. Age it at room temperature for 27 hours, keep it warm at 80°C for 7 hours, and then keep it warm at 115°C for 1.2 hours. Vacuum dry it to constant weight to obtain the product; wherein the amount of deionized water sprayed is 0.45 times the weight gain of the pretreated wood after impregnation treatment, and the volume ratio of the pretreated wood to the modifying liquid is 1:6.

[0038] The preparation method of the functional monomer comprises the following steps:

[0039] Under a nitrogen inert atmosphere, acrolein, acetic acid and anhydrous ethanol were mixed, o-chloroaniline was added, and the mixture was stirred at 62°C and 300 rpm for 5 hours. The solvent was removed by rotary evaporation, and the mixture was freeze-dried to obtain the product; wherein the mass ratio of acrolein, o-chloroaniline, acetic acid and anhydrous ethanol was 3.4:2.2:0.07:22.

[0040] Example 3

[0041] A process for modifying wood with a high-stability composite nanomaterial comprises the following steps:

[0042] Step 1: cleaning the wood surface with deionized water, then drying at 85° C. for 6 h and at 100° C. to constant weight to obtain pretreated wood;

[0043] Step 2: dissolving the functional monomer, N-hydroxyacrylamide and allyl glycidyl ether in anhydrous ethanol, adding a titanate coupling agent and an initiator AIBN, and stirring at 600 rpm for 20 minutes to obtain a modified liquid; wherein the mass ratio of the functional monomer, N-hydroxyacrylamide, allyl glycidyl ether, titanate coupling agent, initiator AIBN and anhydrous ethanol is 8:2.5:1.8:1.5:0.22:40;

[0044] Step 3: Immerse the pretreated wood in the modifying liquid, vacuum impregnate it at a pressure of -1 MPa for 60 minutes, and then pressurize it at a pressure of 1 MPa for 3.0 hours. Take out the wood and spray deionized water on its surface. Age it at room temperature for 30 hours, keep it warm at 80°C for 8 hours, and then keep it warm at 120°C for 1.5 hours. Vacuum dry it to constant weight to obtain the product; wherein the amount of deionized water sprayed is 0.5 times the weight gain of the pretreated wood after impregnation treatment, and the volume ratio of the pretreated wood to the modifying liquid is 1:6.

[0045] The preparation method of the functional monomer comprises the following steps:

[0046] Under a nitrogen inert atmosphere, acrolein, acetic acid and anhydrous ethanol were mixed, o-chloroaniline was added, and the mixture was stirred at 65°C and 400 rpm for 6 hours. The solvent was removed by rotary evaporation, and the mixture was freeze-dried to obtain the product; wherein the mass ratio of acrolein, o-chloroaniline, acetic acid and anhydrous ethanol was 4.0:2.5:0.08:25.

[0047] Comparative Example 1

[0048] Compared with Example 3, Comparative Example 1 is different in that N-hydroxyacrylamide replaces allyl glycidyl ether, and the rest are the same.

[0049] Comparative Example 2

[0050] Compared with Example 3, Comparative Example 2 is different in that N-hydroxyacrylamide replaces the functional monomer, and the rest are the same.

[0051] Comparative Example 3

[0052] Compared with Example 3, Comparative Example 3 is different in that o-chloroaniline is not used, and ethyl methacrylate is used instead of the functional monomer, and the rest are the same.

[0053] Comparative Example 4

[0054] Compared with Example 3, Comparative Example 4 is different in that o-chloroaniline is not used, and aniline is used instead of o-chloroaniline, and the rest are the same.

[0055] Comparative Example 5

[0056] Compared with Example 3, Comparative Example 5 is different in that no titanate coupling agent is used, and the rest are the same.

[0057] Comparative Example 6

[0058] Compared with Example 3, Comparative Example 6 is different in that deionized water is not sprayed in step 3, and the rest are the same.

[0059] The modified wood samples prepared in Examples 1-3 and Comparative Examples 1-6 were tested as follows.

[0060] Compressive strength test: according to GB / T 15777-2017;

[0061] Antibacterial test: Using E. coli as the bacterial species, the modified wood sample was placed in a vessel cultured with E. coli. After 24 hours, the bacterial growth on the surface of the modified wood sample was observed, and the proportion of the surface area without bacterial growth was recorded.

[0062] Hydrophobicity test: The water contact angle of the modified wood samples was measured;

[0063] The above test results are shown in Table 1.

[0064] Table 1 Test results

[0065] Compressive strength (MPa) Contact angle (°) Antibacterial rate (%) Example 1 128.4 163 99.6 Example 2 127.8 161 99.5 Example 3 130.2 164 99.7 Comparative Example 1 108.4 138 89.6 Comparative Example 2 90.5 104 72.5 Comparative Example 3 92.4 114 71.4 Comparative Example 4 124.7 136 91.6 Comparative Example 5 118.6 132 88.5 Comparative Example 6 121.5 141 90.3

[0066] From the test results in Table 1, it can be seen that compared with Comparative Examples 1-6, the modified wood prepared in Examples 1-3 has excellent antibacterial and water-resistant properties, and has excellent compressive strength.

[0067] The present invention can obtain a nano-titanium dioxide structure on the wood surface through hydrolysis of a titanate coupling agent, which can enhance the strength and rigidity of the composite material. At the same time, it can also promote the combination of the rough surface of the nano-titanium dioxide and the hydrophobic polymer to form a micro-nano composite structure, increase the contact angle, and make the modified wood surface super-hydrophobic, which can effectively inhibit the growth of bacteria on the surface.

[0068] The present invention generates a functional monomer containing an unsaturated double bond through a condensation reaction between acrolein and o-chloroaniline. The functional monomer participates in the polymerization reaction of hydroxyacrylamide and allyl glycidyl ether, thereby enhancing the intermolecular force. Combined with the introduced benzene ring structure, the compressive strength of the modified wood can be significantly improved. At the same time, the hydrophobic polymer chain formed can effectively reduce the exposure of the hydrophilic group. The Schiff base in the functional monomer combines the chlorine element, the hydrophobicity of the benzene ring and the photoinhibitory mechanism of titanium dioxide, thereby improving the antibacterial activity of the modified wood through multiple antibacterial mechanisms and destroying bacterial metabolism.

[0069] The present invention uses allyl glycidyl ether as a reaction monomer. The epoxy groups contained in it form chemical bonds with the hydroxyl groups of hydroxyacrylamide and the hydroxyl groups on the surface of wood to form a high-strength three-dimensional network, which significantly improves the compressive strength and deformation resistance. The formation of a dense structure can significantly improve the hydrophobicity and antibacterial properties of the modified wood. In addition, the epoxy groups can also form a chemical force with titanium dioxide, promoting more allyl glycidyl ether to participate in polymerization and facilitating the formation of a denser structure, thereby improving the compressive strength, superhydrophobicity and antibacterial properties of the modified wood.

[0070] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any indirect modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A process for modifying wood with high-stability composite nanomaterials, characterized in that: The process comprises the following steps: Step 1: Clean and dry the wood to obtain pretreated wood; Step 2: dissolving the functional monomer, hydroxyacrylamide and allyl glycidyl ether in anhydrous ethanol, adding a titanate coupling agent and an initiator, and stirring and mixing to obtain a modified liquid; Step 3: soak the pretreated wood in the modified liquid for impregnation treatment, take out the wood, spray deionized water on the surface of the wood, age it, heat and keep it warm, and vacuum dry it to obtain the product.

2. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step 1, the cleaning is to wash the wood surface with deionized water, and the drying is to dry at 85° C. for 4-6 hours and at 100° C. to constant weight.

3. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step 2, the stirring and mixing is carried out at a rotation speed of 400-600 rpm for 15-20 minutes.

4. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step 2, the mass ratio of the functional monomer, hydroxyacrylamide, allyl glycidyl ether, titanate coupling agent, initiator and anhydrous ethanol is 6-8:2.0-2.5:1.4-1.8:1.2-1.5:0.20-0.22:30-40, and the initiator is initiator AIBN.

5. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step three, the volume ratio of the pretreated wood to the modified liquid is 1:

6.

6. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step three, the impregnation treatment is vacuum impregnation at a pressure of -1 MPa for 40-60 minutes, followed by pressure impregnation at a pressure of 1 MPa for 2.0-3.0 hours.

7. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step three, the spraying amount of the deionized water is 0.4-0.5 times the weight gain of the pretreated wood after the impregnation treatment.

8. The process for modifying wood with a high-stability composite nanomaterial according to claim 1, characterized in that: In step three, the aging is carried out at room temperature for 24-30 hours, the heating and heat preservation treatment is carried out at 80° C. for 6-8 hours and then at 110-120° C. for 1.0-1.5 hours, and the vacuum drying is carried out to constant weight.

9. The process for modifying wood with high-stability composite nanomaterials according to claim 1, characterized in that: The preparation method of the functional monomer comprises the following steps: Under an inert atmosphere, acrolein, acetic acid and anhydrous ethanol are mixed, o-chloroaniline is added, heated and stirred, rotary evaporated, and freeze-dried to obtain the product.

10. The process for modifying wood with a high-stability composite nanomaterial according to claim 9, characterized in that: The inert atmosphere is either nitrogen or argon, the heating and stirring are at 60-65° C. and 200-400 rpm for 4-6 hours, and the mass ratio of acrolein, o-chloroaniline, acetic acid, and anhydrous ethanol is 2.8-4.0:2.0-2.5:0.06-0.08:20-25.