A surface treatment device for dimensional stability of wood products and a treatment process thereof

Abstract

The application discloses a kind of wood product dimensional stability surface treatment device and processing technology thereof, including the following steps: wood product surface is cleaned, dry, enzyme solution is uniformly sprayed on wood product surface, and wood product surface is analyzed by spectrum, washed clean, and the lignin removal rate of wood product surface is detected;The wood product of lignin removal is placed in heat treatment furnace, and heating, heat preservation and cooling treatment are sequentially carried out respectively, and the wood product is taken out and ventilated at room temperature;Epoxy resin and hardener are stirred and mixed to obtain a mixture, the mixture is uniformly applied to the surface of wood product, the voids of wood product surface are filled, and solidification is carried out at room temperature;Silane solution is uniformly sprayed on the surface of solidified epoxy resin using spraying method, dried and solidified;The absorption and transmission of moisture by the wood product are blocked, thereby avoiding the expansion or shrinkage of the wood product, and the dimensional stability of the wood product is improved.

Description

Technical Field

[0001] This invention relates to the field of wood product processing, and more particularly to a surface treatment device and process for dimensional stability of wood products. Background Technology

[0002] Dimensional stability of wood products refers to the changes in the dimensions of wood or wood products under different humidity environments. Because wood is a hygroscopic material, it absorbs moisture and expands when the ambient humidity changes, and shrinks when it loses moisture. These dimensional changes can lead to problems such as cracking, warping, and deformation in wood products.

[0003] However, most existing technologies involve drying the wood before processing to reduce its moisture content and minimize dimensional changes during use. However, because the wood still contains a high lignin content, it continues to absorb moisture in humid environments. As the lignin absorbs moisture, the wood product will expand once a certain amount is reached, resulting in deformation and changes in the size of the wood product. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a surface treatment device and process for dimensional stability of wood products.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a surface treatment process for dimensional stability of wood products, comprising the following steps:

[0006] S1: Clean and dry the surface of the wood product, spray the enzyme solution evenly onto the surface of the wood product, let it stand, and perform spectral analysis on the surface of the wood product. After cleaning, test the lignin removal rate of the surface of the wood product.

[0007] S2: Place the wood products with lignin removed into a heat treatment furnace and perform heating, heat preservation and cooling treatments in sequence. After removing the wood products, ventilate them at room temperature.

[0008] S3: Stir and mix the epoxy resin and hardener to obtain a mixture. Apply the mixture evenly to the surface of the wood product to fill the gaps on the surface of the wood product and cure at room temperature.

[0009] S4: Apply the silane solution evenly to the surface of the cured epoxy resin using a spraying method, and then dry and cure it.

[0010] In a preferred embodiment of the present invention, in S1, the enzyme solution concentration is 0.5%-2% u / ml, the enzyme solution is a white rot fungus enzyme solution, and the removal rate is 20%-40%.

[0011] In a preferred embodiment of the present invention, in S1, the standing time is 60min-180min, the temperature is 23-50℃, and the humidity is 60%-90%rh.

[0012] In a preferred embodiment of the present invention, in S2, the heating parameters are a heating rate of 1-5℃ / min and a maximum temperature of 180-200℃.

[0013] In a preferred embodiment of the present invention, in S2, the heat preservation is specifically maintained at a temperature of 180-200°C for 30-60 minutes.

[0014] In a preferred embodiment of the present invention, in step S3, the stirring parameters are: the ratio of epoxy resin to hardener is 1-1.5:1, the hardener is an amine hardener, the stirring time is 2-5 minutes, and the stirring speed is 100-500 rpm.

[0015] In a preferred embodiment of the present invention, in step S4, the concentration of the silane solution is 0.1%-1.0%, the pH value is 3.0-4.5, and the drying temperature is 50℃-70℃.

[0016] A surface treatment apparatus for dimensional stability of wood products includes a conveying mechanism, a heat treatment furnace disposed above the conveying mechanism, and a drying oven.

[0017] Both the heat treatment furnace and the drying oven are equipped with several spray guns. The spray guns are used to spray different materials onto the wood products. The heat treatment furnace is used to heat treat the wood products to cause the internal molecules to polymerize. The drying oven is used to dry the surface of the wood products.

[0018] The conveyor mechanism is used to transport wood products;

[0019] In a preferred embodiment of the present invention, the spray gun in the heat treatment furnace is used to spray the enzyme solution, and the spray gun in the drying oven is used to spray the mixture and epoxy resin.

[0020] In a preferred embodiment of the present invention, the spray guns are respectively arranged in various directions within the heat treatment furnace and the drying chamber, and the nozzles have an atomizing effect.

[0021] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0022] (1) This invention provides a surface treatment device and process for dimensional stability of wood products. By combining enzyme solution, heat treatment and epoxy resin, the enzyme solution is applied to the surface of the wood product to reduce the lignin content in the wood product. The residual lignin is polymerized by heat treatment. Finally, the wood product is filled with epoxy resin. This reduces the absorption and shrinkage of lignin while wrapping the outside with a tight layer of epoxy resin to prevent moisture from entering. Compared with the prior art, this application combines the absorption of moisture by lignin inside the wood product and the transfer of moisture from the outside to the inside of the wood product, thereby blocking the absorption and transfer of moisture by the wood product, thus avoiding the expansion or contraction of the wood product and improving the dimensional stability of the wood product.

[0023] (2) The present invention uses an enzyme solution to treat the surface of wood products, so that lignin peroxidase, manganese peroxidase and laccase constitute the main lignin-degrading enzyme system of white rot fungi. They work together with the lignin-degrading auxiliary enzyme system to degrade lignin. Through the synergistic effect of these enzymes and the lignin-degrading auxiliary enzyme system, lignin on the surface of wood can be effectively removed, thereby reducing the water absorption of the wood products themselves. At the same time, the moisture contained in the residual lignin in the wood products avoids the cracking caused by excessive shrinkage of the wood products, thereby avoiding the expansion and shrinkage of the wood products and improving the dimensional stability of the wood products.

[0024] (3) The present invention uses amine hardeners with small molecular weights, which have good permeability after being mixed with epoxy resin. They can penetrate into the voids formed by the polymerization of lignin on the surface of wood products, thereby filling the voids formed on the surface of wood products. In this way, the epoxy resin forms a thin film on the surface of wood products, which blocks the transfer of moisture into the interior of wood products in humid environments and the evaporation of moisture into the exterior of wood products in dry environments. This prevents the flow of moisture and ensures the dimensional stability of wood products. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of a preferred embodiment of the present invention. Detailed Implementation

[0027] 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.

[0028] like Figure 1 As shown, a surface treatment process for dimensional stability of wood products includes the following steps:

[0029] S1: Clean and dry the surface of the wood product, then spray the enzyme solution evenly onto the surface of the wood product at a rate of 1200-1400 ml / m². 2 Let it stand for 1-3 hours, then clean it thoroughly.

[0030] S2: Place the wood products with lignin removed into a heat treatment furnace and perform heating, heat preservation and cooling treatments in sequence. After removing the wood products, ventilate them at room temperature.

[0031] S3: Mix the epoxy resin and hardener to obtain a mixture. Apply the mixture evenly to the surface of the wood product, with a coating amount of 900-1100 ml / m². 2 It fills the voids on the surface of wood products and cures at room temperature;

[0032] S4: Apply the silane solution evenly to the cured epoxy resin surface using a spraying method. The spraying amount is 1000-1200 ml / m². 2 Then, dry and cure.

[0033] In a preferred embodiment of the present invention, in S1, the enzyme solution concentration is 0.5%-2% u / ml, the enzyme solution is a white rot fungus enzyme solution, the removal rate is 20%-40%, and the temperature is 38°C.

[0034] It should be noted that white-rot fungi are the main fungi that degrade lignin. They can degrade not only lignin in wood, but also polysaccharides such as cellulose and hemicellulose. The lignin-degrading enzymes of white-rot fungi can be classified into the following types:

[0035] 1. Enzymes that directly attack wood or its primary degradation products, including cellulase, hemicellulase, and laccase.

[0036] 2. Enzymes that work in conjunction with the first group of enzymes, including aryl oxidases, glyoxal oxidases, etc.

[0037] 3. This includes glucose oxidase, cellobiose, and cellobiose dehydrogenase, which contain feedback enzymes that play a key role in the biotransformation of high molecular weight wood components. Among them, lignin peroxidase, manganese peroxidase, and laccase constitute the main lignin-degrading enzyme system of white-rot fungi, which work synergistically with lignin-degrading coenzymes to degrade lignin.

[0038] These enzymes work synergistically with lignin-degrading coenzymes to effectively remove lignin from the surface of wood.

[0039] The preparation of white-rot fungal enzymes is specifically as follows:

[0040] Strain selection and cultivation: Select a white-rot fungus strain with lignin-degrading ability, namely *Trichoderma*. Inoculate the strain into a suitable culture medium, namely PDA medium. Cultivate in a constant temperature incubator, typically between 25 and 30°C.

[0041] Enzyme extraction: After reaching maximum enzyme production, the bacterial cells are separated from the culture medium, and the culture medium is collected. The enzyme is extracted from the culture medium using a suitable solvent, namely methanol or ethanol.

[0042] Preparation of enzyme solution: Dissolve the extracted enzyme in an appropriate amount of water to prepare an enzyme solution of a certain concentration. Adjust the pH value and concentration to meet the requirements of subsequent applications.

[0043] Parameter range:

[0044] Strain: White-rot fungus with lignin degradation ability; Culture temperature: 25-30℃; Culture time: 7-14 days; pH value: 4.0-7.0; Solvent: Methanol, ethanol; Enzyme concentration: 0.5%-2% u / ml; Storage temperature: 0℃-4℃.

[0045] In a preferred embodiment of the present invention, in S1, the standing time is 60min-180min, the temperature is 23-50℃, and the humidity is 60%-90%rh.

[0046] In a preferred embodiment of the present invention, in S2, the heat treatment specifically involves heating to polymerize the remaining lignin in the wood product, thereby improving the stability of the wood. The specific operation is as follows:

[0047] S21. Heating: Place the wood in a heat treatment furnace and gradually raise the temperature to approximately 180-200℃. Control the heating rate to within 1-5℃ / minute to avoid excessive heating that could cause the wood to crack.

[0048] S22. Heat preservation: Keep at 180-200℃ for 30 minutes to 1 hour to ensure full polymerization of lignin;

[0049] S23. Cooling: Turn off the heating source and allow the wood to cool naturally to room temperature. The cooling rate should not be too fast to avoid excessive temperature difference between the inside and outside of the wood, which may cause cracking; place the wood in a well-ventilated place and allow it to dry naturally to a stable humidity level.

[0050] It should be noted that lignin is the main component causing moisture absorption and shrinkage in wood. Direct heat treatment can only reduce trace amounts of lignin, leaving a large amount behind, and therefore cannot effectively prevent moisture absorption and shrinkage.

[0051] The main function of heat treatment is to polymerize lignin molecules, thereby reducing intercellular spaces. However, if the lignin content is too high, the degree of polymerization is insufficient, and the intercellular spaces cannot be filled effectively. Pre-treatment with enzymes to reduce the lignin content, followed by heat treatment, allows for more complete polymerization and better filling of the intercellular spaces.

[0052] The effectiveness of direct heat treatment is greatly affected by the type of wood, with different lignin contents resulting in varying effects. However, pre-treatment with enzymes can reduce the differences in lignin content among different types of wood, leading to a more uniform effect in subsequent heat treatment.

[0053] Enzyme treatment and heat treatment have different mechanisms, and their combined use can achieve a synergistic effect, resulting in better treatment effects than using either method alone.

[0054] Therefore, in general, enzymatic treatment followed by heat treatment can more effectively reduce the hygroscopicity and shrinkage of wood, thus achieving a more stable treatment effect.

[0055] In a preferred embodiment of the present invention, in step S3, the stirring parameters are: epoxy resin to hardener ratio of 1-1.5:1, amine hardener selected, stirring time of 2-5 minutes, and stirring speed of 100-500 rpm. The well-mixed epoxy resin mixture is then uniformly sprayed onto the lignin-free wood surface to ensure uniform distribution and close adhesion to the wood surface.

[0056] It should be noted that amine hardeners have a small molecular weight and, when mixed with epoxy resin, have excellent permeability. They can penetrate into the voids created by lignin polymerization on the surface of wood products, thereby filling the voids formed on the surface of the wood products.

[0057] In a preferred embodiment of the present invention, in step S4, the concentration of the silane solution is 0.1%-1.0%, the pH value is 3.0-4.5, and the drying temperature is 50℃-70℃.

[0058] It should be noted that the specific procedure for spraying the silane solution onto the epoxy resin surface is as follows:

[0059] Preparation of silane solution: Dissolve silane in a solvent at the desired concentration to form a silane solution; the solvent is an alcohol-based organic solvent, and the silane concentration is 0.1%-1.0%;

[0060] Coating with silane: The prepared silane solution is evenly sprayed onto the epoxy resin surface. During spraying, it is important to ensure that the silane solution can completely cover the epoxy resin surface and maintain this position for a certain period of time so that the silane and epoxy resin can react fully.

[0061] Drying and curing: After coating, the epoxy resin surface is dried and cured.

[0062] The bonding between silanized coatings and epoxy resins primarily relies on the chemical reaction between silanes and epoxy resins. The active groups in silanes can react with the epoxy groups in epoxy resins to form strong chemical bonds. This bonding method significantly improves the adhesion between the coating and the epoxy resin surface, thereby enhancing the coating's durability and corrosion resistance. Furthermore, the coating formed by the silane solution on the epoxy resin surface is hydrophobic; silane molecules can form a hydrophobic coating on the material surface, thus giving the wood product surface just the right amount of water resistance.

[0063] A surface treatment apparatus for dimensional stability of wood products includes a conveying mechanism, a heat treatment furnace disposed above the conveying mechanism, and a drying oven.

[0064] Both the heat treatment furnace and the drying oven are equipped with several spray guns. The spray guns are used to spray different materials onto the wood products. The heat treatment furnace is used to heat treat the wood products to cause the internal molecules to polymerize. The drying oven is used to dry the surface of the wood products.

[0065] The conveyor mechanism is used to transport wood products;

[0066] In a preferred embodiment of the present invention, the spray gun in the heat treatment furnace is used to spray the enzyme solution, and the spray gun in the drying oven is used to spray the mixture and epoxy resin.

[0067] In a preferred embodiment of the present invention, the spray guns are respectively arranged in various directions within the heat treatment furnace and the drying chamber, and the nozzles have an atomizing effect.

[0068] It should be noted that the conveying mechanism is specifically a flexible conveyor belt. The heat treatment furnace and the drying chamber are both located directly above the conveyor belt, and openings are provided on opposite sides of the conveyor belt in the conveying direction of the heat treatment furnace and the drying chamber. The openings allow the wood products to pass through. When the wood products are undergoing dimensional stability treatment, they are placed on the conveyor belt and intermittently conveyed to the heat treatment furnace and the drying chamber for treatment. Several spray guns are installed in the heat treatment furnace and the drying chamber to spray different treatment liquids onto the wood products and perform different treatments.

[0069] Example 1:

[0070] The wood products are cleaned and dried. Then, they are placed on a conveyor belt. Enzyme solution is loaded into a spray gun inside the heat treatment furnace. The conveyor belt transports the wood products into the furnace, where the spray gun evenly sprays a 1.3% U / ml enzyme solution onto the surface. The humidity is 75% RH. The required temperature and humidity are monitored and adjusted by various modules within the heat treatment furnace. Spectroscopic analysis of the wood product surface shows a lignin removal rate of 38%. Then, a spray gun filled with clean water inside the furnace cleans the wood products. The wood product surface is then dried. After cleaning, the wood products are subjected to heating, heat preservation, and cooling treatments in sequence. The heating parameters are: heating rate of 3℃ / min, maximum temperature of 200℃, heat preservation at 200℃ for 40 minutes, and then ventilation at room temperature after removal. The epoxy resin and hardener are mixed at a ratio of 1:1 for 3 minutes at a stirring speed of 300 rpm. The resulting mixture is then placed in a spray gun inside a drying oven and evenly sprayed onto the surface of the wood product at a spray volume of 1000 ml / m². 2 This allows the mixture to fill the voids on the surface of the wood product and cure at room temperature. A 0.5% silane solution with a pH of 4.1 is then uniformly sprayed onto the cured epoxy resin surface using a spraying method, with a spraying amount of 1100 ml / m². 2 The product is dried at 60℃ and then cured.

[0071] Experiment 1:

[0072] Compared to the treatment process in Example 1, multiple wood products of the same specifications were treated. The wood products treated in Example 1 served as reference group 1, while the others served as control groups. During the treatment process, the concentration of the enzyme solution was varied in each control group to change the lignin removal rate on the surface of each wood product. The wood products were placed indoors at normal humidity (35% RH) for one week. The internal humidity level of the wood products was directly measured using a wood humidity measuring instrument, and the deformation of the wood products was also measured and evaluated. See Table 1 for details.

[0073]

[0074] Table 1

[0075] As shown in Table 1, without using enzyme solution to remove lignin, direct heat treatment of wood products results in less lignin removal. This leads to a high lignin content in the wood products over prolonged use. Lignin has a certain degree of hydrophilicity, allowing it to absorb moisture from the environment, causing the wood products to swell and change in size. While increasing the concentration of the enzyme solution reduces the lignin content and prevents moisture absorption, further increases in enzyme concentration, exceeding 2% U / ml, result in excessively low lignin content and cracking of the wood products.

[0076] Experiment 2:

[0077] Compared to the control groups 1, 2, 3, 4, and 5 in Experiment 1, several more wood products of the same specifications were prepared and treated using the same five processes as control groups 1, 2, 3, 4, and 5. Each control group and control group 1 was placed in environments with humidity levels of 20%, 50%, and 80% RH, respectively. The internal humidity level of the wood products was directly measured using a wood humidity measuring instrument, and the deformation of the wood products was assessed by measuring their dimensions. See Table 2 for details.

[0078]

[0079] Table 2

[0080] According to the data in Table 2, even with a low enzyme solution concentration, in relatively humid or dry environments, the wood products will still expand or shrink due to the absorbency and shrinkage of lignin, leading to cracking or dimensional deformation and ultimately damage. Combining Experiments 1 and 2, the enzyme solution concentration between 0.5% u / ml and 2 u / ml is suitable for lignin treatment, with a preferred concentration of 1.3% u / ml, which achieves the highest lignin removal rate without causing cracking or deformation.

[0081] Experiment 3:

[0082] Compared to the processing method in Example 1, a comparative experiment was conducted by changing the highest temperature of the wood products in the heat treatment furnace. The wood products were placed indoors at normal humidity (35% RH) for one week. The internal humidity level of the wood products was directly measured using a wood humidity measuring instrument, and the deformation of the wood products was evaluated by measuring their dimensions. See Table 3 for details.

[0083]

[0084] Table 3

[0085] Table 3 shows that as the maximum temperature in the heat treatment furnace increases, trace amounts of lignin on the surface of wood products can be removed, thereby reducing the hygroscopic expansion of lignin and preventing deformation of the wood products. Simultaneously, the combination with the enzyme solution (i.e., with Experiment 1) achieves the effect of reducing lignin and improving the dimensional stability of the wood products. As can be seen from control group 10, when the maximum temperature exceeds 200℃, the wood products become too dry due to the excessive temperature, leading to cracking. Therefore, the maximum temperature range for wood products is 180-200℃.

[0086] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A surface treatment process for dimensional stability of wood products, characterized in that, Includes the following steps: S1: Clean and dry the surface of the wood product, spray the enzyme solution evenly onto the surface of the wood product, let it stand, and then clean it. The enzyme solution is a white rot fungus enzyme solution with a concentration of 0.5%u / ml-2%u / ml. S2: Place the wood products with lignin removed into a heat treatment furnace and perform heating, heat preservation and cooling treatments in sequence. After removing the wood products, ventilate them at room temperature with a maximum temperature of 180-200℃. S3: Stir and mix the epoxy resin and hardener to obtain a mixture. Apply the mixture evenly to the surface of the wood product to fill the gaps on the surface of the wood product and cure at room temperature. S4: Apply the silane solution evenly to the surface of the cured epoxy resin using a spraying method, and then dry and cure it.

2. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In S1, the lignin removal rate on the surface of the wood product is 20%-40%.

3. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In S1, the settling time is 60-180 minutes, the temperature is 23-50℃, and the humidity is 60%-90% RH.

4. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In S2, the heating parameters are a heating rate of 1-5℃ / min.

5. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In S2, the heat preservation specifically refers to maintaining a temperature of 180-200℃ for 30-60 minutes.

6. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In step S3, the stirring parameters are as follows: the ratio of epoxy resin to hardener is 1-1.5:1, the hardener is an amine-based hardener, the stirring time is 2-5 minutes, and the stirring speed is 100-500 rpm.

7. The surface treatment process for dimensional stability of wood products according to claim 1, characterized in that: In S4, the concentration of the silane solution is 0.1%-1.0%, the pH value is 3.0-4.5, and the drying temperature is 50℃-70℃.

8. A surface treatment apparatus for dimensional stability of wood products, based on the treatment process according to any one of claims 1-7, comprising a conveying mechanism, a heat treatment furnace disposed above the conveying mechanism, and a drying oven, characterized in that: Both the heat treatment furnace and the drying oven are equipped with several spray guns, which are used to spray different materials onto the wood products; the heat treatment furnace is used to heat treat the wood products to cause the internal molecules to polymerize; the drying oven is used to dry the surface of the wood products. The conveying mechanism is used to transport wooden products.

9. A surface treatment device for dimensional stability of wood products according to claim 8, characterized in that: The spray gun in the heat treatment furnace is used to spray the enzyme solution, and the spray gun in the drying oven is used to spray the mixture and epoxy resin.

10. A surface treatment device for dimensional stability of wood products according to claim 8, characterized in that: The spray guns are respectively positioned in various directions within the heat treatment furnace and the drying chamber, and the nozzles have an atomizing effect.

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