A surface enhancement treatment method for a fat pine and applications thereof

Abstract

The application discloses a surface reinforcement treatment method and application of pine containing fat, and the method comprises the following steps: completely immersing air-dried pine samples in a deionized water solution; after wiping off the excess water on the surface of the immersed pine, placing the pine samples in a mold; after preheating a hot press to 140-160 DEG C, preheating the mold containing the pine samples between hot press plates, and preheating for 10-30 s, obtaining softened pine samples; gradually pressurizing the softened pine samples under the action of mechanical force, the pressure being 5-40 MPa, the closing rate being 0.1-1 mm / s, and the compression amount being 5-20 mm; after reaching the target thickness, forming a closed system between the mold and the upper and lower press plates, and obtaining surface reinforced pine; keeping the surface reinforced pine at 160-200 DEG C for 2-6 h; after the pressure keeping is completed, opening the upper valve of the mold to perform air release treatment, then reducing the temperature of the hot press plate to below 50 DEG C, and releasing the pressure to obtain surface reinforced pine boards. The application can solve the problem that pine tar of pine containing fat is prone to overflow, and can significantly enhance the density, surface hardness and dimensional stability of the pine.

Description

Technical Field

[0001] This invention relates to the field of wood processing technology, and more specifically, to a surface enhancement treatment method and its application for resinous pine wood. Background Technology

[0002] Pine is an important timber species, boasting advantages such as wide distribution, abundant resources, and high economic value. However, pine has well-developed resin ducts and a high resin content, which severely affects the surface finishing and gluing properties of pine components, and solid wood products made from it are prone to resin overflow during use. Furthermore, pine also suffers from defects such as softness, low density, and poor dimensional stability, limiting its processing and utilization. In view of these problems, it is necessary to perform efficient degreasing treatment on pine, combined with reinforcement and modification techniques, to improve its density, hardness, and other physical and mechanical properties, thereby enhancing the quality of pine products and expanding the application range of pine in both structural and non-structural fields.

[0003] The resin in pine wood, also known as rosin, varies in content from 0.8% to 25% depending on the tree species. Rosin consists of solid rosin and liquid turpentine. Turpentine is easily volatile at high temperatures of 150-230℃, and its boiling point can drop below 100℃ when it coexists with water. Previously, methods such as high-temperature steam drying, microwave explosion, and alkaline saponification were used to remove rosin to meet the processing requirements of pine products. However, these methods are time-consuming and energy-intensive, and they do not consider the positive impact of solid rosin on the hydrophobicity, preservative properties, and mechanical properties of pine wood. If rosin could be fixed inside the wood while removing turpentine, it would not only improve the resin exudation phenomenon in pine wood but also provide favorable conditions for subsequent protection and modification of the pine wood.

[0004] Wood surface reinforcement treatment is a green and environmentally friendly method for physical modification of wood. While improving the physical and mechanical properties of fast-growing wood, it significantly reduces volume loss caused by compression compaction. Currently, the methods published in CN107116627A and CN107263657A, by controlling the distribution of moisture and heat within the wood, can selectively compress and compact the wood surface, forming compressed wood with both compressed and uncompressed layers. However, this type of compressed wood has poor dimensional stability, and the deformation caused by compression is easily partially or even completely recovered in liquid or humid environments. CN107053397A discloses a method for fixing wood compression deformation through high-temperature and high-pressure steam treatment, but this method requires high pressure resistance of the tank equipment, has high equipment costs, takes a long time, and its operation and management are complex. CN107234692A and CN116572335A propose a method of first impregnating the wood in phenolic resin and furfuryl alcohol resin impregnation solutions, and then placing it between hot press plates for compression compaction and deformation fixing treatment. However, the introduction of chemical resins can lead to some resins being squeezed out during compression, and the process also presents significant environmental issues. Summary of the Invention

[0005] The purpose of this invention is to provide a surface strengthening treatment method and application for resin-containing pine wood. This invention can solve the problem of resin leakage in resin-containing pine wood, while significantly enhancing the density, surface hardness, and dimensional stability of the pine wood.

[0006] The technical solution of the present invention is as follows: A surface enhancement treatment method for resin-containing pine wood, comprising the following steps:

[0007] Step 1: Completely immerse the air-dried pine wood sample in a deionized water solution, and adjust the immersion time according to the required thickness of the compression layer;

[0008] Step 2: After wiping away excess moisture from the surface of the soaked pine wood, place the pine wood sample in the mold;

[0009] Step 3: After the hot press is preheated to 140-160℃, place the mold containing the pine wood sample between the hot press plates for preheating for 10-30 seconds to obtain the softened pine wood sample.

[0010] Step 4: The softened pine wood sample is gradually pressurized under mechanical force, with a pressure of 5-40 MPa, a closing rate of 0.1-1 mm / s, and a compression amount of 5-20 mm; after the target thickness is reached, the mold and the upper and lower pressure plates are sealed to form a closed system, thus obtaining surface-reinforced pine wood;

[0011] Step 5: Press the surface-reinforced pine wood at 160-200℃ for 2-6 hours;

[0012] Step 6: After holding the pressure, open the valve on the mold to release the air, and then reduce the temperature of the hot press plate to below 50°C to release the pressure and obtain the surface-reinforced pine board.

[0013] In the above-mentioned surface enhancement treatment method for resin-containing pine wood, step 1 includes radiata pine, Masson pine, Scots pine, Douglas fir, slash pine, or larch.

[0014] The aforementioned surface reinforcement treatment method for resin-containing pine wood is characterized in that: the pine wood sample is a tangential board, a radial board, or a tangential-radial board.

[0015] The aforementioned surface enhancement treatment method for resin-containing pine wood, wherein the thickness of the pine wood board is 10-50 mm.

[0016] In the aforementioned surface reinforcement treatment method for resin-containing pine wood, the moisture content of the pine wood sample is 6-12% before soaking in water, and the moisture content of the pine wood sample is greater than 15% after soaking in water.

[0017] In the aforementioned surface enhancement treatment method for resin-containing pine wood, step 2, the mold is a stainless steel compression mold with a sealing ring, and the mold also serves as a thickness gauge with a thickness of 10-30mm.

[0018] In the aforementioned surface reinforcement treatment method for resinous pine wood, in step 3, the pressure of the hot press is set to 0.1 MPa. After the pine wood sample comes into contact with the upper pressure plate, the press is stopped to prevent the sample from being squeezed before it is preheated and softened.

[0019] In the aforementioned surface enhancement treatment method for resinous pine wood, step 4 includes a progressive pressurization cycle of 3 seconds of loading and 5 seconds of holding.

[0020] In the aforementioned surface reinforcement treatment method for resinous pine wood, step 4 involves surface-reinforced pine boards with a compression amount of 5-20 mm, and the thickness of the compression layer on the upper and lower surfaces is 2-10 mm.

[0021] The aforementioned surface-reinforcing treatment method for resin-containing pine wood enables the preparation of surface-reinforced pine wood boards for use in exterior wall cladding, tabletops, flooring, and interior decoration.

[0022] Compared with existing technologies, this invention develops an integrated treatment method for compression reinforcement, degreasing, and shaping of resinous pine wood. This invention has the following advantages:

[0023] 1. This invention uses water as a softener and precisely controls the thickness and density of the wood compression layer by adjusting the wood compression rate. Under low compression rate, a compression layer of about 2-10mm is formed on the upper and lower surfaces of the surface-reinforced pine. The density of the compression layer is more than twice that of the untreated wood. The surface hardness of the surface-reinforced pine is 2-3 times that of the untreated wood. The water contact angle is increased by 40-60° and the surface wettability is significantly reduced.

[0024] 2. After wood compression reinforcement, the evaporation of moisture contained in the wood under the action of the hot press plate creates high-temperature steam treatment conditions in the sealed stainless steel hot press mold, which can achieve in-situ and uniform fixation of wood compression deformation and good dimensional stability.

[0025] 3. When turpentine and water coexist, the boiling point can drop below 100℃. During preheating, compression, and shaping processes, the moisture inside the wood is vaporized, and the turpentine is removed with the steam. The resin inside the wood softens and migrates with the moisture. Some of it forms a solid rosin-filled and fixed layer on the lower surface of the pine sample under the action of gravity and compression. The remaining part diffuses outward from the latewood band and resin ducts and fills the cell pores. This simplifies the pine degreasing process and, by controlling the distribution of resin inside the wood, allows the resin-containing lower surface to retain the hydrophobic and anti-corrosion properties of resin.

[0026] This invention achieves integrated processing of pine wood compression strengthening, degreasing, and shaping, with a green and environmentally friendly process. While ensuring efficient resin removal, it significantly enhances the wood's density, surface hardness, and dimensional stability. This technology only requires hydrothermal softening and compression treatment to achieve resin regulation and quality improvement, reducing the need for degreasing and compression fixing processes. It involves no chemical additives, has low equipment requirements, and is easy to promote and apply, providing technical support for the application of pine wood in exterior wall cladding, tabletops, flooring, and interior decoration. Attached Figure Description

[0027] Figure 1 A photograph of the cross-section of a sample with a compression of 5 mm.

[0028] Figure 2 A photograph of the cross-section of a sample with a compression of 10 mm.

[0029] Figure 3 This is a schematic diagram of the cross-sectional density of a sample with a compression of 5 mm.

[0030] Figure 4 This is a schematic diagram of the cross-sectional density of a sample with a compression of 10 mm.

[0031] Figure 5 SEM image of the lower surface of the pine wood sample;

[0032] Figure 6 SEM image of the upper surface of the pine wood sample;

[0033] Figure 7 A surface color diagram of the pine wood sample;

[0034] Figure 8 Surface wettability diagram of pine wood sample; Detailed implementation method

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0036] Example 1: A surface reinforcement treatment method for resin-containing pine wood:

[0037] The material being treated is radiata pine sawn timber, with dimensions of 300mm × 100mm × 25mm (length × width × thickness), and an initial moisture content of 6-12%. In other embodiments, resin-containing pine species such as Masson pine, Scots pine, Douglas fir, slash pine, and larch can also be used. The pine wood sample can be a tangential board, a radial board, or a tangential-radial board.

[0038] The specific processing procedure includes the following steps:

[0039] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 1.5 hours, and adjust the moisture content of the pine wood to be greater than 15%.

[0040] Step 2: Mold preparation stage: After wiping off excess moisture from the surface of the soaked pine wood, place the pine wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0041] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 160℃, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, and quickly close the hot press. After the upper platen contacts the pine wood sample, preheat for 15 seconds. The hot press pressure is set to 0.1 MPa. Once the pine wood sample contacts the upper platen, immediately stop closing the press to prevent the sample from being squeezed before preheating and softening.

[0042] Step 4: Surface Strengthening Stage: Gradually apply pressure to the pine wood sample. Within one compression cycle, apply pressure for 3 seconds, hold for 5 seconds, maintain pressure at 5-15 MPa, and close at a rate of 0.1-1 mm / s. After reaching the target thickness of 20 mm, the pine wood is sealed to form a closed system. This closed system is achieved by covering the thickness gauge with a sealing strip, which must be able to withstand temperatures above 250℃.

[0043] Step 5: Resin softening, directional deposition, and sealed shaping stage: Under sealed conditions, pressure is maintained for 2 hours. This process softens the resin inside the wood during hot pressing, allowing some resin to diffuse outwards from the latewood, while the remaining resin migrates downwards with the moisture, forming a surface-reinforced pine with both an upper compression layer and a lower compression layer of directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam, creating high-temperature steam inside the sealed mold, achieving uniform and fixed compression deformation of the wood.

[0044] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot press plate to below 50°C, thus depressurizing and obtaining the surface-reinforced pine board.

[0045] Example 2: A surface reinforcement treatment method for resin-containing pine wood:

[0046] The material being processed is radiata pine sawn timber, with dimensions of 300mm×100mm×25mm (length×width×thickness), and an initial moisture content of 6-12%.

[0047] The specific processing procedure includes the following steps:

[0048] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 2 hours, and control the moisture content of the pine wood to be greater than 15%.

[0049] Step 2: Mold preparation stage: Place the water-soaked wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0050] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 150℃, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, and quickly close the hot press. After the upper platen contacts the pine wood sample, preheat for 20 seconds. The hot press pressure is set to 0.1MPa. Once the pine wood sample contacts the upper platen, immediately stop closing the press to prevent the sample from being squeezed before preheating and softening.

[0051] Step 4: Surface strengthening stage: Gradually pressurize the pine wood sample. In one compression cycle, the load is applied for 3 seconds and held for 5 seconds. The pressure is 15 MPa and the closing rate is 0.1-1 mm / s. After the target thickness of 20 mm is reached, the pine wood is sealed to form a closed system.

[0052] Step 5: Resin Softening, Directional Deposition, and Sealed Shaping Treatment Stage: After heating the upper and lower plates of the hot press to 160℃, maintain pressure for 4 hours under sealed conditions. This process softens the resin inside the wood during hot pressing, with some resin spreading outwards from the latewood and the remaining resin migrating downwards with the moisture, forming a surface-reinforced pine wood with both an upper compression layer and a lower compression layer with directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam. High-temperature steam is then generated inside the sealed mold, achieving uniform compression deformation and fixation of the wood.

[0053] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot press plate to below 50°C, thus depressurizing and obtaining the surface-reinforced pine board.

[0054] Example 3: A surface reinforcement treatment method for resin-containing pine wood:

[0055] The material being processed is radiata pine sawn timber, with dimensions of 300mm×100mm×25mm (length×width×thickness), and an initial moisture content of 6-12%.

[0056] The specific processing procedure includes the following steps:

[0057] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water for 2.5 hours, and adjust the moisture content of the pine wood to be greater than 15%.

[0058] Step 2: Mold preparation stage: Place the water-soaked wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0059] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 145°C, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, quickly close the hot press, and preheat for 30 seconds after the upper plate comes into contact with the pine wood sample.

[0060] Step 4: Surface strengthening stage: Gradually pressurize the pine wood sample. In one compression cycle, the load is applied for 3 seconds and held for 5 seconds. The pressure is 15 MPa and the closing rate is 0.1-1 mm / s. After the target thickness of 20 mm is reached, the pine wood is sealed to form a closed system.

[0061] Step 5: Resin Softening, Directional Deposition, and Sealed Shaping Treatment Stage: After heating the upper and lower plates of the hot press to 160℃, maintain pressure under sealed conditions for 6 hours. This process softens the resin inside the wood during hot pressing, with some resin spreading outwards from the latewood and the remaining resin migrating downwards with the moisture, forming a surface-reinforced pine wood with both an upper compression layer and a lower compression layer with directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam, creating high-temperature steam inside the sealed mold, achieving uniform and fixed compression deformation of the wood.

[0062] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot press plate to below 50°C, thus depressurizing and obtaining the surface-reinforced pine board.

[0063] Example 4: A surface reinforcement treatment method for resin-containing pine wood:

[0064] The material being processed is radiata pine sawn timber, with dimensions of 300mm×100mm×30mm (length×width×thickness), and an initial moisture content of 6-12%.

[0065] The specific processing procedure includes the following steps:

[0066] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 2 hours, and control the moisture content of the pine wood to be greater than 15%.

[0067] Step 2: Mold preparation stage: Place the water-soaked wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0068] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 150°C, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, quickly close the hot press, and preheat for 30 seconds after the upper plate comes into contact with the pine wood sample.

[0069] Step 4: Surface strengthening stage: Gradually pressurize the pine wood sample at a pressure of 20-30 MPa and a closing rate of 0.1-1 mm / s. After reaching the target thickness of 20 mm, the pine wood is sealed to form a closed system.

[0070] Step 5: Resin Softening, Directional Deposition, and Sealed Shaping Treatment Stage: After heating the upper and lower plates of the hot press to 160℃, maintain pressure under sealed conditions for 2 hours. This process softens the resin inside the wood during hot pressing, with some resin spreading outwards from the latewood and the remaining resin migrating downwards with the moisture, forming a surface-reinforced pine wood with both an upper compression layer and a lower compression layer with directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam, creating high-temperature steam inside the sealed mold, achieving uniform and fixed compression deformation of the wood.

[0071] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot press plate to below 50°C, thus depressurizing and obtaining the surface-reinforced pine board.

[0072] Example 5: A surface reinforcement treatment method for resin-containing pine wood:

[0073] The material being processed is radiata pine sawn timber, with dimensions of 300mm×100mm×30mm (length×width×thickness), and an initial moisture content of 6-12%.

[0074] The specific processing procedure includes the following steps:

[0075] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 3 hours, and control the moisture content of the pine wood to be greater than 15%.

[0076] Step 2: Mold preparation stage: Place the water-soaked wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0077] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 160°C, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, quickly close the hot press, and preheat for 25 seconds after the upper plate comes into contact with the pine wood sample.

[0078] Step 4: Surface strengthening stage: Gradually pressurize the pine wood sample at a pressure of 25 MPa and a closing rate of 0.1-1 mm / s. After reaching the target thickness of 20 mm, the pine wood is sealed to form a closed system.

[0079] Step 5: Resin softening, directional deposition, and sealed shaping stage: Under sealed pressure for 4 hours, the resin inside the wood softens during hot pressing. Some resin diffuses from the latewood outwards, while the remaining resin migrates downwards with the moisture, forming a surface-reinforced pine wood with both an upper compression layer and a lower compression layer of directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam, creating high-temperature steam inside the sealed mold, achieving uniform and fixed compression deformation of the wood.

[0080] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and pass cold water to reduce the temperature of the hot press plate to below 50°C. The internal moisture content of the wood will drop to below 8%, and the pressure will be released to obtain the surface-reinforced pine board.

[0081] Example 6: A surface reinforcement treatment method for resin-containing pine wood:

[0082] The material being processed is radiata pine sawn timber, with dimensions of 300mm×100mm×30mm (length×width×thickness), and an initial moisture content of 6-12%.

[0083] The specific processing procedure includes the following steps:

[0084] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 4 hours, and control the moisture content of the pine wood to be greater than 15%.

[0085] Step 2: Mold preparation stage: Place the water-soaked wood sample in a custom-made stainless steel hot press mold. The mold frame also serves as a thickness gauge, with a thickness of 20mm.

[0086] Step 3: Preheating and softening stage: Preheat the upper and lower plates of the hot press to 160°C, then place the stainless steel hot press mold containing the pine wood sample between the hot press plates, quickly close the hot press, and preheat for 20 seconds after the upper plate comes into contact with the pine wood sample.

[0087] Step 4: Surface strengthening stage: Gradually pressurize the pine wood sample at a pressure of 25 MPa and a closing rate of 0.1-1 mm / s. After reaching the target thickness of 20 mm, the pine wood is sealed to form a closed system.

[0088] Step 5: Resin softening, directional deposition, and sealed shaping stage: Under sealed pressure for 6 hours, the resin inside the wood softens during hot pressing. Some resin diffuses from the latewood outwards, while the remaining resin migrates downwards with the moisture, forming a surface-reinforced pine wood with both an upper compression layer and a lower compression layer of directional resin deposition. Simultaneously, the moisture inside the wood is vaporized, and the turpentine is removed with the steam, forming high-temperature steam inside the sealed mold, achieving uniform and fixed compression deformation of the wood.

[0089] Step 6: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot press plate to below 50°C, thus depressurizing and obtaining the surface-reinforced pine board.

[0090] Example 7: The surface-reinforced pine boards prepared in Examples 1-6 are used for exterior wall cladding, tabletops, flooring, or interior decoration.

[0091] Comparative Example 1: Performance tests were conducted directly on untreated radiated air-dried lumber, including density, color, hardness, and surface wettability. The results are listed in Tables 1 and 2.

[0092] Comparative Example 2: The treated object was radiata pine sawn timber with dimensions of 300mm×100mm×30mm (length×width×thickness) and an initial moisture content of 6-12%.

[0093] The specific processing procedure includes the following steps:

[0094] Step 1: Soaking stage: Completely immerse the air-dried pine wood sample in deionized water solution for 2 hours, and control the moisture content of the pine wood to be greater than 15%.

[0095] Step 2: Resin softening, directional deposition, and airtight shaping treatment stage: The water-soaked pine wood sample is placed in a custom-made stainless steel mold; the hot press is preheated to 160℃ and the pressure is set to 0.1MPa. The stainless steel mold containing the pine wood sample is placed in the hot press; after the upper pressure plate comes into contact with the pine wood sample, the pressure is maintained for 2 hours, so that the pine resin inside the wood softens and migrates downward with the moisture during the hot pressing process.

[0096] Step 3: Cooling and depressurization stage: Open the depressurization valve on the sealed stainless steel mold, and let cold water flow to reduce the temperature of the hot plate to below 50°C, thus depressurizing and obtaining the pine board with resin filling on the lower surface.

[0097] To further illustrate the technical effects of the present invention, performance tests were conducted on Examples 1-6 and Comparative Examples 1-2, including density, microstructure, hardness, surface wettability, and dimensional stability, to evaluate the changes in the physical and mechanical properties of the surface-reinforced pine boards.

[0098] Table 1 shows the characterization results of the compression layer features of surface-reinforced pine boards in Examples 1-6 and Comparative Examples 1-2.

[0099]

[0100] Table 1

[0101] Table 2 shows the changes in colorimetric values, surface hardness, and dimensional stability of surface-reinforced pine wood in Examples 1-6 and Comparative Examples 1-2.

[0102]

[0103]

[0104]

[0105] Table 2

[0106] Compressed wood (i.e., surface-reinforced pine board) was prepared according to the method in Example 1. Samples with a compression of 5 mm and 10 mm were selected for experimental analysis, and the results are as follows: Figures 1-4 As shown, where Figure 1 This is a photograph of the cross-section of a sample with a compression of 5 mm. Figure 2 This is a photograph of the cross-section of a sample with a compression of 10 mm. Figure 3 This is a schematic diagram of the cross-sectional density of a sample with a compression of 5 mm. Figure 4 This is a schematic diagram of the cross-sectional density of a sample with a compression of 10 mm; based on Figure 1-4 The results indicate that reinforced pine wood with a resin-filled lower surface was successfully prepared under the conditions of this invention. From... Figure 3 , Figure 4 The cross-sectional density curves and the results in Table 1 show that after surface reinforcement treatment, a compression layer with a thickness of approximately 2-5 mm is formed on both the upper and lower surfaces of the pine wood sample. The peak density and average density of the compression layer increase to 1.00 g / cm³. 3 and 0.77 g / cm 3 These are 2.5 times and 2 times the comparative examples, respectively.

[0107] Furthermore, scanning electron microscopy (SEM) images were performed on the upper and lower surfaces of the sample with a compression of 10 mm. Figure 5 SEM image of the lower surface of the sample; Figure 6 This is a SEM image of the upper surface of the sample. Figure 5 and Figure 6 The results showed that after surface reinforcement treatment, the morphology of tracheids in the pine samples changed significantly. From the surface of the sample inwards, the degree of deformation of the tracheid cell cavities gradually decreased, which was consistent with its cross-sectional density distribution curve. Compared with the upper surface compression layer, most of the tracheid cell cavities in the lower surface compression layer were filled with resin.

[0108] Furthermore, the upper and lower surfaces of the samples from Examples 1-3 and Comparative Examples 1-2 were compared, and the results are as follows: Figure 7 As shown, the samples of Examples 1-3 of the present invention are obviously significantly different from those of Comparative Examples 1-2 in terms of surface material color, and resin deposition is obviously visible on the lower surface.

[0109] Furthermore, the surface hardness and surface wettability of the surface-reinforced pine wood of the present invention were characterized. Figure 8 The diagram shows the surface wettability of each pine wood sample. From... Figure 8 The results show that the surface hardness of the embodiments of the present invention is 2-3 times that of the comparative example. Compared with Comparative Example 1, the water contact angle of the sample in the embodiments increased by 40-60°, and the surface wettability was significantly reduced. In the embodiments, the water contact angle of the upper surface compression layer tended to stabilize at 40s, while the water contact angle of the lower surface compression layer containing rosin was stabilized at 10s, indicating that the rosin deposited in the compression layer has the ability to delay water absorption.

[0110] Finally, the dimensional stability of surface-reinforced pine was characterized. Table 2 shows that the water absorption deformation recovery rate of surface-reinforced pine decreased with increasing treatment time. When the treatment time reached 6 hours, the water absorption deformation recovery rate of surface-reinforced pine with a compression amount of 5 mm decreased to 8.98%; that of surface-reinforced pine with a compression amount of 10 mm decreased to 13.10%. Its shaping effect was significantly better than that of atmospheric pressure heat treatment at the same temperature, indicating that hot-press sealing shaping treatment is an effective and energy-saving method for fixing the compression deformation of wood.

[0111] In summary, the surface-reinforced pine board of this invention possesses excellent mechanical properties, good dimensional stability, and surface hydrophobicity. It improves the quality of resinous pine wood, broadens the application fields of pine timber, and is expected to be used in exterior wall cladding, tabletops, flooring, and decorative materials.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for surface reinforcement treatment of resin-containing pine wood, characterized in that: The steps include the following: Step 1: Completely immerse the air-dried pine wood sample in a deionized water solution, adjusting the immersion time according to the required thickness of the compression layer; the thickness of the pine wood sample is 10-50 mm; before immersion, the moisture content of the pine wood sample is 6-12%, and after immersion, the moisture content of the pine wood sample is greater than 15%; Step 2: After wiping off excess moisture from the surface of the soaked pine wood, place the pine wood sample in the mold; the mold is a stainless steel compression mold with a sealing ring, and the mold also serves as a thickness gauge, with a thickness of 10-30 mm. Step 3: After the hot press is preheated to 140-160℃, place the mold containing the pine wood sample between the hot press plates for preheating for 10-30 seconds to obtain the softened pine wood sample; set the hot press pressure to 0.1 MPa, and stop the press from closing after the pine wood sample contacts the upper pressure plate to prevent the sample from being squeezed before it is preheated and softened. Step 4: The softened pine wood sample is progressively pressurized under mechanical force, with a pressure of 5-40 MPa, a closing rate of 0.1-1 mm / s, and a compression amount of 5-20 mm; after reaching the target thickness, the mold and the upper and lower pressure plates are sealed to form a closed system, thus obtaining surface-reinforced pine wood; the progressive pressurization cycle includes a 3s loading period and a 5s holding period. Step 5: Press the surface-reinforced pine wood at 160-200℃ for 2-6 hours; Step 6: After holding the pressure, open the valve on the mold to release the air, and then reduce the temperature of the hot press plate to below 50°C to release the pressure and obtain the surface-reinforced pine board.

2. The surface reinforcement treatment method for resin-containing pine wood according to claim 1, characterized in that: In step 1, the pine wood includes radiata pine, Masson pine, Scots pine, Douglas fir, slash pine, or larch.

3. The surface reinforcement treatment method for resin-containing pine wood according to claim 1, characterized in that: The pine wood sample is a tangential board, a radial board, or a tangential-radial board.

4. The surface reinforcement treatment method for resin-containing pine wood according to claim 1, characterized in that: In step 4, the surface-reinforced pine board with a compression amount of 5-20 mm has a compression layer thickness of 2-10 mm on both the upper and lower surfaces.

5. The application of the surface strengthening treatment method for resin-containing pine wood according to any one of claims 1-4, characterized in that: Surface-reinforced pine boards are prepared for use in exterior wall cladding, tabletops, flooring, and interior decoration.

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