Method for improving heat-conducting property of wood
By constructing a continuous metal thermally conductive network inside the wood, the problem of poor improvement in the thermal conductivity of wood in existing technologies has been solved, resulting in wood materials with high thermal conductivity, suitable for applications such as electric heating floors.
Patent Information
- Application Number
- CN202511200997.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-26
- Publication Date
- 2025-12-02
AI Technical Summary
Existing technologies for improving the thermal conductivity of wood are complex and ineffective, making them unsuitable for large-scale production.
A continuous metal thermally conductive network is constructed inside the wood by vacuum impregnation with a metal salt solution and in-situ chemical reduction. This process includes metal ion infiltration, reduction to elemental metals, and chemical plating, forming a metal nanoparticle composite material.
It significantly improves the thermal conductivity of wood, increasing the thermal conductivity coefficient to 0.2472–0.3117 W/mK, making it suitable for applications requiring longitudinal heat conduction, such as electric heating floors. The process is also compatible with various metals and is suitable for mass production.
Smart Images
Figure CN121043221A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of new materials, nanomaterials and functionalized materials, and specifically to a method for improving the thermal conductivity of wood. Background Technology
[0002] Wood, as a natural material, generally has low thermal conductivity, typically ranging from 0.10 W / mK to 0.12 W / mK. The root cause of wood's low thermal conductivity lies primarily in its complex multi-scale porous structure. This structure includes micron-scale vessels, tracheids, wood fiber cell cavities, and resin ducts, as well as nanoscale cell wall pores and microfibril gaps. The air trapped within these pores significantly hinders heat transfer, particularly suppressing the transport pathways of phonons (the primary carriers of heat conduction in non-metallic solids).
[0003] In wood that has undergone delignification pretreatment, a metal salt solution (as a precursor for metal nanoparticles) is introduced through vacuum impregnation, and the metal ions are further converted into elemental metal nanoparticles through in-situ chemical reduction. This allows a continuous metal thermal conductivity network to be constructed in situ within the pores and channels of the wood, thereby effectively improving the thermal conductivity of the wood.
[0004] Currently, the common method to improve the thermal conductivity of wood materials is through impregnation, which introduces a highly thermally conductive medium into the pores of the wood. This method generally requires high reaction conditions, has a relatively poor improvement effect, and is not suitable for large-scale production. Summary of the Invention
[0005] The purpose of this invention is to provide a method for improving the thermal conductivity of wood. The method provided by this invention is simple, and the finished product has high thermal conductivity and processability, making it suitable for mass production.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] This invention provides a method for improving the thermal conductivity of wood, comprising the following steps:
[0008] The delignified wood is placed in a solution of metal salts and subjected to a first vacuum treatment, which allows metal ions to penetrate into the internal pores of the wood, resulting in wood loaded with metal ions.
[0009] Wood loaded with metal ions is placed in a reducing agent solution and subjected to a second vacuum treatment to reduce the metal ions loaded in the wood to elemental metal, thus obtaining wood loaded with elemental metal.
[0010] Wood loaded with elemental metals is placed in a plating solution containing metal ions for chemical plating to obtain a metal nanoparticle wood composite material.
[0011] Preferably, the metal salt solution is a silver salt solution, a copper salt solution, or a nickel salt solution; the concentration of the metal salt solution is 0.08 mol / L to 0.1 mol / L.
[0012] Preferably, the silver salt solution is a silver nitrate solution; the copper salt solution is a hydrochloric acid solution of copper nitrate; and the nickel salt solution is a hydrochloric acid solution of nickel sulfate.
[0013] Preferably, the reducing agent solution comprises a sodium borohydride solution, or a mixed solution of sodium borohydride and NaOH; the concentration of the reducing agent solution is 0.158 mol / L to 0.396 mol / L.
[0014] Preferably, when the silver salt solution is a silver nitrate solution, the electroless plating is performed using a silver mirror reaction.
[0015] Preferably, when the metal salt solution is a copper salt solution, the electroless plating includes a complexation reaction and a reduction reaction performed sequentially; the complexation reaction solution is a mixed solution of a copper plating complexing agent, a soluble copper salt, and a copper plating stabilizer; the copper plating reducing agent for the reduction reaction is a formaldehyde solution.
[0016] The electroless plating steps include:
[0017] After placing the wood loaded with elemental metals into the complexing reaction solution and performing a third vacuum treatment, the pH of the reaction system was adjusted to alkaline to carry out the reduction reaction.
[0018] Preferably, when the metal salt solution is a nickel salt solution, the plating solution comprises a mixed solution of soluble nickel salt, nickel plating reducing agent, nickel plating complexing agent and nickel plating stabilizer;
[0019] The electroless plating steps include:
[0020] After placing the wood loaded with elemental metals into a plating bath containing nickel ions for a fourth vacuum treatment, the pH of the reaction system is adjusted to alkaline before nickel plating.
[0021] Preferably, the nickel plating complexing agent is sodium citrate; the nickel plating reducing agent is sodium hypophosphite; the nickel plating stabilizer is thiourea; the copper plating complexing agent is disodium ethylenediaminetetraacetate and sodium potassium tartrate; and the copper plating stabilizer is potassium ferrocyanide.
[0022] The present invention also provides a metal nanoparticle wood composite material prepared by the method described above, wherein the thermal conductivity of the metal nanoparticle wood composite material is 0.2472 to 0.3117 W / mK.
[0023] The present invention also provides the application of the metal nanoparticle wood composite material described above in electrically heated floors or wood veneers.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] (1) In-situ metal network thermal conductivity: Through nanopore creation and vacuum impregnation (metal ions → reduction → activation), a continuous metal thermal conductivity network is constructed in the pores of wood, bridging phonon paths and significantly reducing thermal resistance. This high thermal conductivity wood can be widely used in electrothermal conversion fields such as electric heating floors.
[0026] (1) In-situ Metal Network Thermal Conductivity: Through nanopore-forming and vacuum impregnation (metal ion → reduction → activation) processes, a continuous metal thermal conductivity network is constructed inside the pores of the wood, allowing the phonon conduction path to run from the bottom to the top of the wood, thereby effectively reducing longitudinal thermal resistance and significantly improving overall thermal conductivity. Compared with traditional processes, this method does not only form a metal layer on the surface of the wood, but also achieves the construction of a thermal conductivity network from the inside out. Therefore, it is more suitable for applications requiring longitudinal heat conduction, such as electric heating floors and high-efficiency electrothermal conversion materials.
[0027] (2) Adjustable thermal conductivity: By selecting the type of metal (silver / copper / nickel) and adjusting the process parameters, the heat conduction network can be precisely controlled, achieving a wide range of improvements in the thermal conductivity of wood. In addition, the process is compatible with various metal salts and corresponding reduction systems, providing diversified solutions.
[0028] (3) Complete and practical structure: Optimize delignification and drying processes to maintain the porous structure and mechanical properties of wood; the metal network is embedded without damage, and the finished product has high thermal conductivity and processability, making it suitable for mass production. Attached Figure Description
[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0030] Figure 1 This is a SEM image of the metal nanoparticle wood composite material prepared in Example 1 of the present invention;
[0031] Figure 2 EDS image of the metal nanoparticle wood composite material prepared in Example 1 of this invention;
[0032] Figure 3 This is a SEM image of the metal nanoparticle wood composite material prepared in Example 2 of the present invention;
[0033] Figure 4 EDS image of the metal nanoparticle wood composite material prepared in Example 2 of this invention;
[0034] Figure 5 This is a SEM image of the metal nanoparticle wood composite material prepared in Example 3 of the present invention;
[0035] Figure 6 This is an EDS image of the metal nanoparticle wood composite material prepared in Example 3 of the present invention. Detailed Implementation
[0036] This invention provides a method for improving the thermal conductivity of wood, comprising the following steps:
[0037] The delignified wood is placed in a solution of metal salts and subjected to a first vacuum treatment, which allows metal ions to penetrate into the internal pores of the wood, resulting in wood loaded with metal ions.
[0038] Wood loaded with metal ions is placed in a reducing agent solution and subjected to a second vacuum treatment to reduce the metal ions loaded in the wood to elemental metal, thus obtaining wood loaded with elemental metal.
[0039] Wood loaded with elemental metals is placed in a plating solution containing metal ions for chemical plating to obtain a metal nanoparticle wood composite material.
[0040] This invention places delignified wood in a solution of metal salts and performs a first vacuum treatment, allowing metal ions to penetrate into the internal pores of the wood, resulting in wood loaded with metal ions.
[0041] As one embodiment of the present invention, the acquisition of the delignified wood includes the following steps: placing the wood in a mixed solution of sodium hydroxide and sodium sulfite for delignification treatment, then further treating the delignified wood in H2O2 solution for 2 hours, rinsing with deionized water and freeze-drying to obtain delignified wood.
[0042] In one embodiment of the present invention, the mass concentration of sodium hydroxide in the mixed solution of sodium hydroxide and sodium sulfite can be 10%; the mass concentration of sodium sulfite can be 5%; the temperature of the delignification treatment is preferably 60°C, and the time is preferably 4 hours; the delignification treatment can partially remove lignin and create pores in the wood cell walls; in one embodiment of the present invention, the concentration of the H2O2 solution can be 0.25 mol / L; in one embodiment of the present invention, the freeze-drying time can be 24 to 38 hours, specifically 24 hours.
[0043] In one embodiment of the present invention, the metal salt solution is one or more of silver salt solution, copper salt solution and nickel salt solution; the silver salt solution can be silver nitrate solution; the copper salt solution can include hydrochloric acid solution of copper nitrate; the nickel salt solution can be hydrochloric acid solution of nickel sulfate solution; the concentration of the metal salt in the metal salt solution can be 0.08 mol / L to 0.1 mol / L, specifically 0.08 mol / L, 0.09 mol / L or 0.1 mol / L.
[0044] In one embodiment of the present invention, the pressure of the first vacuuming process can be 0.05 to 0.1 MPa, specifically 0.05 MPa, 0.06 MPa, 0.07 MPa or 0.08 MPa; the time can be 10 to 15 min, specifically 10 min, 11 min, 12 min, 13 min, 14 min or 15 min.
[0045] This invention involves placing wood loaded with metal ions in a reducing agent solution and performing a second vacuum treatment to reduce the metal ions loaded in the wood to elemental metals, thereby obtaining wood loaded with elemental metals.
[0046] In one embodiment of the present invention, the reducing agent solution includes a sodium borohydride solution or a mixed solution of sodium borohydride and sodium hydroxide; the concentration of the reducing agent solution can be 0.158 mol / L to 0.396 mol / L, specifically 0.15 mol / L, 0.2 mol / L, 0.3 mol / L or 0.35 mol / L.
[0047] In one embodiment of the present invention, the pressure of the second vacuuming process can be 0.05 to 0.1 MPa, specifically 0.05 MPa, 0.06 MPa, 0.07 MPa or 0.08 MPa; the time can be 1.5 to 7 min, specifically 1.5 min, 5 min or 7 min.
[0048] This invention involves placing wood loaded with elemental metals in a plating solution containing metal ions for chemical plating to obtain a metal nanoparticle wood composite material.
[0049] In one embodiment of the present invention, when the silver salt solution is a silver nitrate solution, the electroless plating adopts a silver mirror reaction method.
[0050] In one embodiment of the present invention, when the metal salt solution is a copper salt solution, the electroless plating includes a complexation reaction and a reduction reaction performed sequentially; the complexation reaction solution is a mixed solution of a copper plating complexing agent, a soluble copper salt, and a copper plating stabilizer; the copper plating reducing agent in the reduction reaction is a formaldehyde solution; in another embodiment of the present invention, the copper plating complexing agent can be disodium ethylenediaminetetraacetate and sodium potassium tartrate; the copper plating stabilizer can be potassium ferrocyanide.
[0051] When the metal salt solution is a copper salt solution, the chemical plating step includes: placing the wood loaded with elemental metal in a complexing reaction solution for a third vacuum treatment, adjusting the pH of the reaction system to alkaline, and carrying out a reduction reaction.
[0052] In one embodiment of the present invention, the pressure of the third vacuuming process is 0.05 to 0.1 MPa, specifically 0.05 MPa, 0.06 MPa, 0.07 MPa or 0.08 MPa; the time is 1 to 5 min, specifically 1 min, 2 min, 3 min, 4 min or 7 min.
[0053] In one embodiment of the present invention, when the metal salt solution is a nickel salt solution, the plating solution comprises a mixed solution of soluble nickel salt, nickel plating reducing agent, nickel plating complexing agent and nickel plating stabilizer; the nickel plating complexing agent may be sodium citrate; the nickel plating reducing agent may be sodium hypophosphite; and the nickel plating stabilizer may be thiourea.
[0054] In one embodiment of the present invention, when the metal salt solution is a nickel salt solution, the chemical plating step includes: placing the wood loaded with elemental metal in a plating solution containing nickel ions for a fourth vacuum treatment, adjusting the pH of the reaction system to alkaline, and then performing nickel plating.
[0055] In one embodiment of the present invention, the pressure of the fourth vacuuming process is 0.05 to 0.1 MPa, specifically 0.05 MPa, 0.06 MPa, 0.07 MPa or 0.08 MPa; the time is 1 to 5 min, specifically 1 min, 2 min, 3 min, 4 min or 7 min.
[0056] The present invention also provides a metal nanoparticle wood composite material prepared by the method described above; as one embodiment of the present invention, the thermal conductivity of the metal nanoparticle wood composite material is 0.2472 to 0.3117 W / mK.
[0057] The present invention also provides the application of the metal nanoparticle wood composite material described above in electrically heated floors or wood veneers.
[0058] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.
[0059] The wood used in the examples is cherry wood, which has a thermal conductivity of 0.2472 W / mK.
[0060] Example 1
[0061] Preparation of delignified wood: The wood was treated in a mixed solution of sodium hydroxide and sodium sulfite (10 wt.% sodium hydroxide and 5 wt.% sodium sulfite) at 60°C for 4 h to partially remove lignin and create pores in the wood cell walls; then it was treated with 0.25 mol / L H2O2 solution for 2 h, then rinsed with deionized water and freeze-dried for 24 h.
[0062] Silver ion impregnation: The wood was immersed in a 0.1 mol / L silver nitrate solution and then subjected to vacuum treatment (10 min, 0.08 MPa).
[0063] Silver ion reduction: The wood soaked with silver metal ions was transferred to a 0.2 mol / L sodium borohydride solution and vacuum-treated at 0.08 MPa for 5 min to obtain wood loaded with elemental silver.
[0064] Silver plating: Prepare a 0.15 mol / L silver nitrate solution, then add ammonia and sodium hydroxide until the precipitate disappears. Immerse the silver-loaded wood in the above solution and vacuum it for 2 min at 0.08 MPa. Then, add a 0.05 mol / L glucose solution dropwise and react at 60 °C for 20 min to obtain a silver nanoparticle wood composite material.
[0065] The longitudinal direction of the silver nanoparticle wood composite material obtained in Example 1 was observed using a scanning electron microscope, and the results are as follows: Figure 1 As shown. From Figure 1 As can be seen, the 4-hour delignification treatment creates a small number of pores on the surface, and a large number of silver particles are attached to the surface, which are evenly distributed and have a significant silver particle adhesion effect.
[0066] The longitudinal elemental analysis of the metal nanoparticle wood composite material obtained in Example 1 was observed, and the results are shown in the figure. Figure 2 , Figure 2 The distribution diagram of carbon (C), oxygen (O), and silver (Ag) is shown from... Figure 2 It can be seen that silver particles have a good distribution and covering effect on the surface of wood after delignification treatment.
[0067] The thermal conductivity of silver nanoparticle wood composite material was tested using a thermal conductivity meter (JTKD-Ⅱ type, Xiangtan Instrument Co., Ltd.), and its thermal conductivity increased from 0.2472 W / mK to 0.3117 W / mK.
[0068] Example 2
[0069] Preparation of delignified wood: Wood was treated in a mixed solution of sodium hydroxide and sodium sulfite (10 wt.% sodium hydroxide and 5 wt.% sodium sulfite) at 60°C for 4 h to partially remove lignin and create pores in the wood cell walls; then treated with 0.25 mol / L hydrogen peroxide solution for 2 h; then rinsed with deionized water and freeze-dried for 38 h.
[0070] Copper ion impregnation: Wood was immersed in a mixed solution of 0.329 mol / L hydrochloric acid and 0.08 mol / L copper nitrate under vacuum (15 min, 0.08 MPa).
[0071] Metal ion reduction: The wood soaked in copper metal ions was transferred to a mixed solution of 0.396 mol / L sodium borohydride and 0.3 mol / L sodium hydroxide and vacuumed for 7 min at 0.08 MPa to obtain copper-loaded wood.
[0072] Copper plating: Wood loaded with copper was placed in a mixed solution of 0.118 mol / L disodium ethylenediaminetetraacetate, 0.095 mol / L potassium sodium tartrate, 0.501 mol / L copper sulfate, and 0.013 mol / L potassium ferrocyanide and subjected to vacuum treatment (2 min, 0.08 MPa). The pH of the system was then adjusted to 9 using 25 wt.% sodium hydroxide solution. 1.33 mol / L formaldehyde solution was added, and the pH was adjusted to 11.5 using 25 wt.% sodium hydroxide solution. The reaction was carried out at 60 °C for 10 min to obtain copper nanoparticle wood composite material.
[0073] The longitudinal direction of the copper nanoparticle wood composite material obtained in Example 2 was observed using a scanning electron microscope, and the results are as follows: Figure 3 As shown. From Figure 3 As can be seen, the copper plating is evenly applied to the surface of the wood, with fine particles and a smooth surface.
[0074] The longitudinal elemental analysis of the copper nanoparticle wood composite material obtained above was observed, and the results are as follows: Figure 4 As shown, Figure 4 The copper element is evenly distributed and there are no obvious defects, indicating that the coating quality is good.
[0075] The thermal conductivity of copper nanoparticle wood composite material was tested using a thermal conductivity meter (JTKD-Ⅱ type, Xiangtan Instrument Co., Ltd.), and its thermal conductivity increased from 0.2472 W / mK to 0.3085 W / mK.
[0076] Example 3
[0077] Preparation of delignified wood: The wood was placed in a mixed solution of sodium hydroxide and sodium sulfite (sodium hydroxide mass concentration of 10% and sodium sulfite mass concentration of 5%) at 60℃ for 4h to partially remove lignin and create pores in the wood cell walls; then it was treated with 0.25mol / L hydrogen peroxide solution for 2h; then it was rinsed with deionized water and freeze-dried for 38h.
[0078] Nickel ion impregnation: Wood was immersed in a mixed solution of 0.164 mol / L hydrochloric acid and 0.09 mol / L nickel sulfate under vacuum (10 min, 0.08 MPa).
[0079] Metal ion reduction: The wood soaked in nickel metal ions was transferred to a mixed solution of 0.158 mol / L sodium borohydride and 0.375 mol / L sodium hydroxide and subjected to vacuum treatment (90 s, 0.08 MPa) to obtain wood loaded with elemental nickel.
[0080] Nickel plating: Wood loaded with nickel was placed in a mixed solution of 0.213 mol / L nickel sulfate, 0.117 mol / L sodium citrate, 0.318 mol / L sodium hypophosphite and 0.0004 mol / L thiourea and subjected to vacuum treatment (2 min, 0.08 MPa). The pH was then adjusted to 9 with ammonia and reacted at 60 °C for 15 min to obtain nickel nanoparticle wood composite material.
[0081] The longitudinal direction of the nickel nanoparticle wood composite material was observed using scanning electron microscopy, and the results are as follows: Figure 5 As shown. From Figure 5 It can be seen that the nickel plating is evenly distributed inside the wood, with moderately sized particles and a smooth surface.
[0082] Elemental analysis of the longitudinal application of nickel nanoparticle wood composites was conducted, and the results are as follows: Figure 6 As shown, Figure 6 The display shows that the nickel element is evenly distributed and there are no obvious defects, indicating that the coating quality is good.
[0083] The thermal conductivity of nickel nanoparticle wood composite material was tested using a thermal conductivity meter (JTKD-Ⅱ type, Xiangtan Instrument Co., Ltd.), and its thermal conductivity increased from 0.2472 W / mK to 0.2894 W / mK.
[0084] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for improving the thermal conductivity of wood, characterized in that, Includes the following steps: The delignified wood is placed in a solution of metal salts and subjected to a first vacuum treatment, which allows metal ions to penetrate into the pores inside the wood, resulting in wood loaded with metal ions. Wood loaded with metal ions is placed in a reducing agent solution and subjected to a second vacuum treatment to reduce the metal ions loaded in the wood to elemental metal, thus obtaining wood loaded with elemental metal. Wood loaded with elemental metals is placed in a plating solution containing metal ions for chemical plating to obtain a metal nanoparticle wood composite material.
2. The method as described in claim 1, characterized in that, The metal salt solution is a silver salt solution, a copper salt solution, or a nickel salt solution; the concentration of the metal salt solution is 0.08 mol / L to 0.1 mol / L.
3. The method as described in claim 1, characterized in that, The silver salt solution is a silver nitrate solution; the copper salt solution is a copper nitrate hydrochloric acid solution; and the nickel salt solution is a nickel sulfate hydrochloric acid solution.
4. The method as described in claim 1, characterized in that, The reducing agent solution includes a sodium borohydride solution, or a mixed solution of sodium borohydride and NaOH; the concentration of the reducing agent solution is 0.158 mol / L to 0.396 mol / L.
5. The method as described in claim 3, characterized in that, When the silver salt solution is a silver nitrate solution, the electroless plating is performed using a silver mirror reaction.
6. The method as described in claim 1, characterized in that, When the metal salt solution is a copper salt solution, the electroless plating includes a complexation reaction and a reduction reaction performed sequentially; the complexation reaction solution is a mixed solution of a copper plating complexing agent, a soluble copper salt, and a copper plating stabilizer; the copper plating reducing agent for the reduction reaction is a formaldehyde solution. The steps of the electroless plating include: After placing the wood loaded with elemental metals into the complexing reaction solution and performing a third vacuum treatment, the pH of the reaction system was adjusted to alkaline to carry out the reduction reaction.
7. The method as described in claim 1 or 6, characterized in that, When the solution of the metal salt is a nickel salt solution, the plating solution comprises a mixed solution of soluble nickel salt, nickel plating reducing agent, nickel plating complexing agent and nickel plating stabilizer; The steps of the electroless plating include: After placing the wood loaded with elemental metals into a plating bath containing nickel ions for a fourth vacuum treatment, the pH of the reaction system is adjusted to alkaline before nickel plating.
8. The method as described in claim 7, characterized in that, The nickel plating complexing agent is sodium citrate; the nickel plating reducing agent is sodium hypophosphite; the nickel plating stabilizer is thiourea; the copper plating complexing agent is disodium ethylenediaminetetraacetate and sodium potassium tartrate; and the copper plating stabilizer is potassium ferrocyanide.
9. The metal nanoparticle wood composite material prepared by the method according to any one of claims 1 to 8, characterized in that, The thermal conductivity of the metal nanoparticle wood composite material is 0.2472–0.3117 W / mK.
10. The application of the metal nanoparticle wood composite material according to claim 9 in electrically heated floors or wood veneers.