Preparation method of organosilicone modified formaldehyde-free amino resin and wood modification application of organosilicone modified formaldehyde-free amino resin

Abstract

The invention relates to the technical field of amino resin, and discloses a preparation method of organosilicone modified formaldehyde-free amino resin and wood modification application of the organosilicone modified formaldehyde-free amino resin, the preparation method comprises the following steps: 1) adding glyoxal into a reaction kettle, adjusting the pH value to 4.0-6.0, adding melamine, heating to 40-50 DEG C, and reacting for 30-60 minutes; (2) adding urea and a dispersing agent into the reaction kettle for the first time, heating to 50-70 DEG C, and reacting for 30-60 minutes; 3) adding urea, organic silicide and deionized water for the second time into the reaction kettle, and reacting for 1-3 hours; (4) adding the flame retardant into the reaction kettle, stirring for 30 minutes, and adjusting the pH value to 7.0-9.0 to obtain the organic silicon modified formaldehyde-free amino resin. By controlling the reaction conditions and the raw material adding sequence, the multi-aspect performance is improved, the flexibility and the impact resistance of the resin are enhanced, the toughness and the quality are improved, and the flame-retardant function is achieved.

Description

Technical Field

[0001] This invention relates to the technical field of amino resins, and more specifically, to a method for preparing organosilicon-modified formaldehyde-free amino resins and their application in wood modification. Background Technology

[0002] Resin impregnation modification technology is an industrially applied wood modification method that can effectively improve the dimensional stability and mechanical strength of plantation timber, and is an important way to realize the value-added utilization of plantation timber. Recently, with the increasing awareness of green environmental protection, traditional three-aldehyde resin wood modification technology, due to its formaldehyde content and poor environmental performance, has limited the application range of modified boards. Therefore, developing formaldehyde-free wood modification technology has become an urgent need for industry development.

[0003] In the prior art, CN114196161A has developed a wood modifier, melamine-urea-glyoxal (MUG) resin. Although it achieves zero formaldehyde emissions, the resin suffers from insufficient toughness after curing, resulting in reduced impact resistance in the modified wood. Therefore, it is necessary to modify the MUG resin, such as by adding polymer segments or crosslinking monomers, to alleviate its brittleness to some extent. Organosilicon compounds have good stability and heat resistance, and they readily undergo intramolecular chain rotation, exhibiting good flexibility. Therefore, introducing organosilicon compounds into MUG resin can improve its toughness, stability, and heat resistance, while also further improving the overall performance of wood impregnated with organosilicon-modified MUG resin.

[0004] This patented invention differs from other organosilicon-modified urea-formaldehyde resins, phenolic resins, and polyacrylate emulsion resins. The preparation of these resins primarily involves introducing organosilicon compounds into the resin molecules, resulting in polymers with a wide molecular weight distribution, ranging from hundreds to thousands, or even tens of thousands, used for wood bonding to improve adhesive strength. In contrast, this invention synthesizes a low-molecular-weight resin wood modifier that can be penetrated into wood cells through external forces to achieve wood modification. Therefore, controlling the synthesis process of organosilicon-modified MUG resin is crucial for preparing resins for wood modification. Currently, there are no reports on the synthesis of organosilicon-modified MUG resin; therefore, this invention designs a novel wood modifier to promote the green and environmentally friendly modification of solid wood. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing organosilicon-modified formaldehyde-free amino resin, which aims to solve the problem of insufficient toughness of formaldehyde-free amino resin after curing in the prior art.

[0006] This invention is achieved through a method for preparing organosilicon-modified formaldehyde-free amino resin, comprising the following preparation steps: 1) Add glyoxal to the reaction vessel, adjust the pH of glyoxal to 4.0~6.0 using a pH adjuster, add melamine, stir glyoxal and melamine evenly, raise the temperature to 40℃~50℃, and react for 30min~60min; 2) Add the first batch of urea and dispersant to the reactor, heat to 50℃~70℃, and react for 30min~60min; 3) Add a second batch of urea, organosilicon compound, and deionized water to the reactor and react for 1 to 3 hours; 4) Add flame retardant to the reaction vessel, stir for 30 minutes, adjust the pH value to 7.0~9.0 using a pH adjuster, cool and discharge to obtain organosilicon modified formaldehyde-free amino resin.

[0007] Furthermore, according to the component mass percentage ratio, the organosilicon-modified formaldehyde-free amino resin includes 20%~35% glyoxal, 5%~20% melamine, 10%~40% urea, 5%~20% organosilicon compounds, 2%~10% dispersant, and 1%~5% flame retardant, wherein the urea includes primary urea and secondary urea.

[0008] Furthermore, in preparation step 3), the organosilicon compound includes one or more of sodium methylsilicate, hydroxyl-terminated polydimethylsiloxane, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0009] Furthermore, in preparation step 2), the dispersant includes one or more of polyvinyl alcohol, polyethylene glycol, ethylene glycol, glycerol, isopropanol, pentaerythritol, ethanol, and methanol.

[0010] Furthermore, in preparation steps 1) and 4), the pH adjuster is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium silicate, and potassium silicate.

[0011] Furthermore, in preparation step 4), the flame retardant includes one or more of the following: ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, boric acid, and borax.

[0012] Furthermore, the mass ratio of the first urea to the second urea is (2~3):1.

[0013] Furthermore, the organosilicon-modified formaldehyde-free amino resin prepared by the method can be used to modify and apply to wood.

[0014] Further modifications include the following steps: 1) Obtain logs, air-dry the logs to a moisture content of 60%~20%, and then process the logs into boards; 2) The board is immersed in silicone-modified formaldehyde-free amino resin. The silicone-modified formaldehyde-free amino resin and the board are placed in a vacuum pressurization device. The board is vacuum pressurized and impregnated using the vacuum pressurization device so that the silicone-modified formaldehyde-free amino resin penetrates into the board to achieve the set penetration amount. The vacuum pressurization equipment has a vacuum range of -0.05MPa to -0.1MPa and a pressurization range of 0.6MPa to 2.0MPa for vacuum pressurizing organosilicon-modified formaldehyde-free amino resin-impregnated wood. 3) Remove the board from the silicone-modified formaldehyde-free amino resin, first air-dry the board for 2-3 days, then dry the board at a temperature of 40℃-80℃ until the moisture content of the board is 5%-10%.

[0015] Furthermore, the logs are coniferous and broad-leaved wood.

[0016] Compared with existing technologies, the method for preparing organosilicon-modified formaldehyde-free amino resin provided by this invention achieves multifaceted performance improvements by controlling reaction conditions and the order of raw material addition. Specifically, these improvements include the following: 1) In the initial stage of the reaction, glyoxal and melamine are fully reacted in a reaction vessel at a specific pH value and temperature, thereby constructing the basic framework of the resin and providing a basis for subsequent modification.

[0017] 2) Add urea and dispersant in stages, and combine with organosilicon compounds so that the flexible components of organosilicon are incorporated into the resin molecular chains during the growth process; Among them, the intermolecular forces of organosilicon compounds are relatively weak. Their introduction weakens the rigid connection between resin molecules, enhances the flexibility and impact resistance of the resin at the molecular level, and thus improves the toughness and quality of the formaldehyde-free amino resin after curing.

[0018] 3) The addition of flame retardants and the adjustment of pH value endow the resin with good flame retardant properties, while ensuring the stability of the resin reaction system. The resulting organosilicon-modified formaldehyde-free amino resin achieves a synergistic improvement in toughness, water resistance and flame retardancy while maintaining environmental protection characteristics. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the method for preparing organosilicon-modified formaldehyde-free amino resin provided by the present invention. Figure 2 This is a schematic diagram of the internal structure of the reaction vessel provided by the present invention; Figure 3 This invention provides Figure 2 An enlarged view of the area marked A in the middle.

[0020] In the figure: reaction vessel 100; stirring chamber 200; vibrating plate 201; upper chamber 202; lower chamber 203; inner wall 204; annular groove 205; Stirring shaft 300, motor 301, upper section 302, lower section 303, spring 304, fixed cylinder 305, elastic plate 306, movable end 307. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0023] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0024] Reference Figure 1-3 The image shows a preferred embodiment of the present invention.

[0025] A method for preparing organosilicon-modified formaldehyde-free amino resin includes the following preparation steps: 1) Add glyoxal to the reaction vessel, adjust the pH of glyoxal to 4.0~6.0 using a pH adjuster, add melamine, stir glyoxal and melamine evenly, raise the temperature to 40℃~50℃, and react for 30min~60min; 2) Add the first batch of urea and dispersant to the reactor, heat to 50℃~70℃, and react for 30min~60min; 3) Add the second batch of urea, organosilicon compound, and deionized water to the reactor and react for 1 to 3 hours; 4) Add flame retardant to the reactor, stir for 30 minutes, adjust the pH value to 7.0~9.0 using pH adjuster, cool and discharge to obtain organosilicon modified formaldehyde-free amino resin.

[0026] The method for preparing organosilicon-modified formaldehyde-free amino resin provided above achieves multifaceted performance improvements by controlling reaction conditions and the order of raw material addition. Specifically, these improvements include the following: 1) In the initial stage of the reaction, glyoxal and melamine are fully reacted in a reaction vessel at a specific pH value and temperature, thereby constructing the basic framework of the resin and providing a basis for subsequent modification.

[0027] 2) Add urea and dispersant in stages, and combine with organosilicon compounds so that the flexible components of organosilicon are incorporated into the resin molecular chains during the growth process; Among them, the intermolecular forces of organosilicon compounds are relatively weak. Their introduction weakens the rigid connection between resin molecules, enhances the flexibility and impact resistance of the resin at the molecular level, and thus improves the toughness and quality of the formaldehyde-free amino resin after curing.

[0028] 3) The addition of flame retardants and the adjustment of pH value endow the resin with good flame retardant properties, while ensuring the stability of the resin reaction system. The resulting organosilicon-modified formaldehyde-free amino resin achieves a synergistic improvement in toughness, water resistance and flame retardancy while maintaining environmental protection characteristics.

[0029] In this embodiment, according to the component mass percentage ratio, the organosilicon modified formaldehyde-free amino resin includes 20%~35% glyoxal, 5%~20% melamine, 10%~40% urea, 5%~20% organosilicon compounds, 2%~10% dispersant, and 1%~5% flame retardant. The urea includes primary urea and secondary urea.

[0030] In this way, the reasonable combination of components according to their mass percentage ratio fully leverages their respective performance advantages. Among them, glyoxal, as the basic reactant, reacts with melamine to form a stable macromolecular skeleton, while the gradual addition of urea further promotes the cross-linking and growth of molecular chains, enhancing the resin's adhesion and water resistance.

[0031] The addition of organosilicon compounds, with their flexible molecular chains, can weaken the brittleness of the cured resin, thereby enhancing the toughness of the cured formaldehyde-free amino resin.

[0032] In addition, the use of dispersants improves the uniformity of each component and avoids local aggregation that affects performance. At the same time, the proportion of flame retardants gives the final resin good flame retardant properties.

[0033] By precisely controlling the mass percentage of each component, this silicone-modified formaldehyde-free amino resin achieves a balance in impact resistance, water resistance, flame retardancy, and environmental friendliness, making it suitable for use as a wood modifier and improving the dimensional stability and mechanical strength of wood.

[0034] In this embodiment, in preparation step 3), the organosilicon compound includes one or more of sodium methylsilicate, hydroxyl-terminated polydimethylsiloxane, vinyltriethoxysilane, and vinyltrimethoxysilane.

[0035] Sodium methylsilicate can provide basic flexibility, while hydroxyl-terminated polydimethylsiloxane, with its long-chain flexible molecular structure, can weaken the rigid connections between resin molecules and reduce brittleness after curing.

[0036] Vinyltriethoxysilane and vinyltrimethoxysilane can further form a cross-linked network through vinyl reactions, achieving a balance between flexibility and strength.

[0037] By selecting a combination of one or more organosilicon compounds, the molecular structure of the resin is optimized, so that the cured product not only has excellent flexibility, but also retains good heat resistance and water resistance. In practical applications, such as when used to modify plantation timber, this optimized resin can improve the impact resistance of the wood, improve its dimensional stability, and meet the needs of high-quality wood products.

[0038] In this embodiment, in preparation step 2), the dispersant includes one or more of polyvinyl alcohol, polyethylene glycol, ethylene glycol, glycerol, isopropanol, pentaerythritol, ethanol, and methanol.

[0039] Polyvinyl alcohol and polyethylene glycol, as high molecular weight dispersants, can be used to encapsulate urea particles, preventing them from agglomerating and thus promoting the uniform dispersion of urea in the reaction system.

[0040] Small molecule dispersants such as ethylene glycol and glycerol improve the mixing effect of each component by reducing the surface tension of the system.

[0041] In this way, the use of dispersants improves the uniformity of the reaction system, which is particularly important for subsequent reactions, especially when adding the second urea and organosilicon compounds, to ensure the uniform growth and cross-linking of resin molecular chains.

[0042] In practical applications, such as when resin needs to be vacuum pressurized in wood modification, the presence of dispersants makes it easier for the resin to penetrate into the wood cell walls, improving the modification effect and production efficiency, and providing a guarantee for the manufacture of high-quality wood products.

[0043] In this embodiment, the pH adjuster is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium silicate, and potassium silicate.

[0044] In step 1), by adding an appropriate amount of sodium hydroxide or potassium hydroxide, the pH value of glyoxal can be adjusted to 4.0~6.0, providing an optimal acidic environment for the reaction of melamine and glyoxal, thereby ensuring the efficient progress of the reaction.

[0045] In subsequent steps, sodium carbonate or potassium carbonate can be further fine-tuned to a neutral range to create conditions for urea to participate in the reaction. This dynamic pH control improves the overall performance of the cured product. For example, when modifying wood, precise pH control helps to improve the resin's permeability and adhesion, and enhance the dimensional stability and mechanical strength of the wood.

[0046] In this embodiment, in preparation step 4), the flame retardant includes one or more combinations of ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, boric acid, and borax.

[0047] Among them, flame retardants such as ammonium phosphate and diammonium hydrogen phosphate decompose to produce phosphoric acid and ammonia when heated. Phosphoric acid can promote the formation of a protective char layer on the surface of wood, while ammonia can effectively dilute flammable gases, thereby reducing the risk of combustion.

[0048] Boric acid and borax melt to form a glassy substance that covers the surface of the material, isolating it from oxygen and heat.

[0049] The synergistic effect of this multiple flame-retardant combination not only improves the fire safety of modified wood, but also retains other excellent properties of the resin, including flexibility and water resistance.

[0050] In this embodiment, the mass ratio of the first urea to the second urea is (2~3):1.

[0051] Thus, the first addition of more urea allows it to react rapidly with melamine and glyoxal to form a stable amino resin base structure; while the second addition of less urea is mainly used to synergize with organosilicon compounds to further optimize the degree of cross-linking and flexibility of the molecular chains.

[0052] This precise control of the quality ratio not only avoids the side reactions caused by excessive urea, but also ensures that the resin's flexibility and strength reach the optimal balance.

[0053] When used to modify wood, this optimized resin can improve the wood's impact resistance and dimensional stability, while reducing production costs and increasing economic benefits.

[0054] In this embodiment, the reactor 100 has a stirring chamber 200 inside, and a stirring shaft 300 arranged longitudinally is provided in the middle of the stirring chamber 200. The bottom of the stirring shaft 300 is movably abutted against the bottom of the stirring chamber 200, and the top of the stirring shaft 300 extends out of the reactor 100 and is connected to a motor 301. The motor 301 drives the stirring shaft 300 to rotate. The stirring shaft 300 is connected to a vibrating disk 201 that reciprocates longitudinally along the axial direction of the stirring shaft 300. The outer periphery of the vibrating disk 201 abuts against the inner wall 204 of the stirring chamber 200. The vibrating disk 201 divides the stirring chamber 200 into an upper chamber 202 for stirring and a lower chamber 203 that is empty. The upper chamber 202 is located above the vibrating disk 201, and the lower chamber 203 is located below the vibrating disk 201. The upper chamber 202 and the lower chamber 203 are arranged in isolation from each other. The stirring shaft 300 has an upper section 302 located in the upper cavity 202 and a lower section 303 located in the lower cavity 203. A spring 304 is sleeved on the lower section 303. The bottom of the spring 304 is fixedly arranged, and the top of the spring 304 abuts against the vibrating plate 201 from bottom to top. Multiple stirring blades are provided on the outer periphery of the upper section 302. During the stirring process of the stirring shaft 300, the spring 304 is in an elastic compression state, and the vibrating plate 201 moves back and forth along the longitudinal direction of the stirring shaft 300 as the pressure changes, so that the vibrating plate 201 is in a longitudinal vibration state.

[0055] During the rotation of the stirring shaft 300, the elastic compression of the spring 304 causes the vibrating plate 201 to move up and down with the pressure change, forming longitudinal vibration. This vibration not only breaks the local reaction equilibrium in the stirring chamber 200, but also promotes the uniform mixing and heat transfer of materials. Especially when organosilicon compounds and urea are gradually added, it ensures that the reaction proceeds fully.

[0056] This dynamic stirring improves the stirring effect and reaction efficiency, and in practical applications, it can significantly shorten the reaction time and improve production efficiency.

[0057] In this embodiment, a plurality of fixed cylinders 305 are connected to the upper section 302, and the plurality of fixed cylinders 305 are arranged sequentially at intervals along the axial direction of the upper section 302; a plurality of longitudinally elastically deformable elastic plates 306 are connected to the outer periphery of the fixed cylinders 305, the elastic plates 306 form stirring blades, and the plurality of elastic plates 306 are arranged sequentially at intervals along the circumferential direction of the upper section 302. The inner end of the elastic sheet 306 is connected to the fixed cylinder 305, and the outer end of the elastic sheet 306 is movably arranged to form a movable end 307; the inner sidewall 204 of the upper cavity 202 is recessed to form an annular groove 205, the annular groove 205 is arranged around the circumference of the upper cavity 202, and the annular groove 205 undulates in a wave-like manner along the circumference of the upper cavity 202, and the movable end 307 is movably placed in the annular groove 205; During the stirring process of the stirring shaft 300, the movable end 307 of the elastic sheet 306 moves in a wave-like manner along the annular groove 205, so that the elastic sheet 306 reciprocates longitudinally elastically deforms.

[0058] This allows the elastic sheet 306 to enhance the uniformity and intensity of stirring, thereby helping to evenly disperse the components and ultimately improve the performance stability of the silicone-modified formaldehyde-free amino resin.

[0059] In this embodiment, the organosilicon-modified formaldehyde-free amino resin prepared by the method for preparing organosilicon-modified formaldehyde-free amino resin is applied to the modification of wood.

[0060] By modifying formaldehyde-free amino resin with organosilicon, it can penetrate deep into the cell wall of wood to form a uniform modified layer. After curing, the flexibility and high strength of the resin improve the impact resistance of the wood. At the same time, its water resistance and flame retardant properties enable the wood to maintain excellent mechanical properties in humid and high-temperature environments.

[0061] This type of modified wood, which improves quality and toughness, can be widely used in high-end furniture and building decoration materials, realizing the high added value utilization of wood.

[0062] This embodiment includes the following modification steps: 1) Obtain logs, air-dry the logs to a moisture content of 20%~60%, and then process the logs into board-shaped timber. 2) Immerse the board-shaped wood in silicone-modified formaldehyde-free amino resin. Place the silicone-modified formaldehyde-free amino resin and the board-shaped wood in a vacuum pressurization device. Use the vacuum pressurization device to pressurize the silicone-modified formaldehyde-free amino resin so that the silicone-modified formaldehyde-free amino resin penetrates into the board-shaped wood to achieve the set penetration amount. The vacuum pressurization equipment can apply vacuum pressure to silicone-modified formaldehyde-free amino resin-impregnated wood within a vacuum range of -0.05 MPa to -0.1 MPa and a pressurization range of 0.6 MPa to 2.0 MPa. 3) Remove the board-shaped wood from the organosilicon-modified formaldehyde-free amino resin, first air-dry the board-shaped wood for 2-3 days, and then dry the board-shaped wood at a temperature of 40℃-80℃ until the moisture content of the board-shaped wood is 5%-10%.

[0063] Through precise process control, the efficient bonding between silicone-modified resin and wood is ensured: First, the raw wood is air-dried to a suitable moisture content and then made into boards, which helps to improve the resin penetration efficiency; then, the resin is uniformly penetrated into the wood through a vacuum pressurization device, achieving uniform impregnation.

[0064] Especially during the drying process, gradually reducing the moisture content of the wood to 5%~10% not only prevents the wood from cracking, but also allows the resin to fully solidify inside the wood, forming a stable modified structure, thereby improving the overall performance of the wood.

[0065] In this embodiment, the raw wood is coniferous and broad-leaved wood; it can be eucalyptus, red oak, white oak, teak, oak, birch, Masson pine, cedar, etc. The selection of coniferous and broad-leaved wood as the modification object gives full play to its advantages of moderate density and uniform texture.

[0066] The cell wall structure of coniferous and broad-leaved wood is relatively dense, but under vacuum pressure, organosilicon-modified resin can still efficiently penetrate into the interior of the wood to form a uniform modified layer. The modified coniferous and broad-leaved wood has improved impact toughness, dimensional stability and flame retardancy, making it suitable for producing high-quality furniture and decorative materials to meet market demand.

[0067] Two specific embodiments are provided below. Example 1 The preparation process of sodium methylsilicate modified melamine-urea-glyoxal (MUG) resin is as follows: 1) Add glyoxal to the reaction vessel, adjust the pH of glyoxal to 6.0 using sodium hydroxide, add melamine, stir the glyoxal and melamine evenly, raise the temperature to 40℃~50℃, and react for 45 minutes; 2) Add the first batch of urea and ethanol to the reactor, heat to 70°C, and react for 45 minutes; 3) Add the second batch of urea, sodium methylsilicate, and deionized water to the reactor and react for 1 hour; 4) Add ammonium dihydrogen phosphate to the reactor, stir for 30 minutes, adjust the pH value to 8.0 with sodium hydroxide, cool and discharge to obtain organosilicon modified MUG resin.

[0068] In the examples, the components were formulated according to their mass percentages, including 20% ​​glyoxal, 5% melamine, 10% urea, 5% organosilicon compounds, 3% dispersant, 1% flame retardant, and deionized water.

[0069] The process of wood impregnation modification is as follows: The fir wood boards were placed in an impregnation tank and evacuated to -0.1 MPa for 0.5 hours. While maintaining the vacuum, a silicone resin-modified MUG resin modifier with a solid content of 21.5% was introduced, ensuring the wood was completely immersed in the modifier. The tank was then pressurized to 1.0 MPa and maintained for 12 hours. After this, the impregnation solution was drained, the wood was removed, and air-dried for 3 days. Subsequently, the wood was subjected to step drying at 40℃, 60℃, and 80℃ until the moisture content of the modified wood reached 5%–10%.

[0070] Example 2 The preparation process of vinyltriethoxysilane modified melamine-urea-glyoxal (MUG) resin is as follows: 1) Add glyoxal to the reaction vessel, adjust the pH of glyoxal to 5.5 using sodium hydroxide, add melamine, stir glyoxal and melamine evenly, heat to 40℃~50℃, and react for 30 minutes. 2) Add the first batch of urea and polyethylene glycol to the reactor, heat to 60°C, and react for 30 minutes; 3) Add the second batch of urea, vinyltriethoxysilane, and deionized water to the reactor and react for 1 hour; 4) Add boric acid and borax to the reactor, stir for 30 minutes, adjust the pH value to 8.0 with sodium hydroxide, cool and discharge to obtain organosilicon modified MUG resin.

[0071] In the examples, the components were formulated according to their mass percentages, including 25% glyoxal, 10% melamine, 15% urea, 5% organosilicon compounds, 5% dispersant, 1% flame retardant, and deionized water.

[0072] The process of wood impregnation modification is as follows: The fir wood boards were placed in an impregnation tank and evacuated to -0.1 MPa for 0.5 hours. While maintaining the vacuum, a silicone resin-modified MUG resin modifier with a solid content of 24.2% was introduced, ensuring the wood was completely immersed in the modifier. The tank was then pressurized to 1.0 MPa and maintained for 12 hours. After this, the impregnation solution was drained, the wood was removed, and air-dried for 3 days. Subsequently, the wood was subjected to step drying at 40℃, 60℃, and 80℃ until the moisture content of the modified wood reached 5%–10%.

[0073] Compare with Example 1 The control example is an untreated cedar wood sample.

[0074] The following are the test results for organosilicon-modified formaldehyde-free amino resin modifiers: The wood modifiers of Examples 1-2 were tested in six aspects: appearance, solid content, relative molecular mass, viscosity, storage stability, and water miscibility. The results are shown in Table 1.

[0075] The method for determining the solid content is as follows: Take 1-1.5g of each of the resin modifiers from Examples 1-2, place them in an oven at 102℃ and dry to constant weight, then calculate the percentage of the remaining portion by mass after drying to obtain the solid content. Viscosity was measured using a Forte 4 cup. The relative molecular mass of the MUG resin was measured using electrospray ionization mass spectrometry.

[0076] Table 1 Performance test results of organosilicon-modified MUG resin

[0077] Test results show that Examples 1-2 are all pale yellow semi-transparent solutions with relative molecular weights mainly distributed between 200 and 600, viscosity values ​​between 12 and 14s, and good storage stability. They are miscible with water in any proportion.

[0078] The physical and mechanical properties of the modified material were determined as follows: The dimensional stability, oven-dry density, bending strength (MOR), and modulus of elasticity (MOE) of the modified timber in Examples 1-3 and the control example were tested according to the national standards GB / T 1934.2-2009 "Determination of Wet Swelling of Timber", GB / T 1933-2009 "Determination of Density of Timber", GB / T 1936.1-2009 "Test Method for Bending Strength of Timber" and GB / T 1936.2-2009 "Determination Method for Bending Modulus of Elasticity of Timber". The results are shown in Table 2.

[0079] The results showed that, compared with the unmodified wood in Control Example 1, the modified wood in Examples 1-2 all had improved oven-dry density, dimensional stability, bending strength (MOR), and modulus of elasticity (MOE). This indicates that the organosilicon-modified MUG resin entered the wood and played a role in physical filling and binding with the chemical components of the wood. After the resin was cured, the dimensional stability and mechanical properties of the wood were significantly improved.

[0080] Table 2 Physical and mechanical properties of modified and unmodified wood

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing organosilicon-modified formaldehyde-free amino resin, characterized in that, The preparation steps include the following: 1) Add glyoxal to the reaction vessel, adjust the pH of glyoxal to 4.0~6.0 using a pH adjuster, add melamine, stir glyoxal and melamine evenly, raise the temperature to 40℃~50℃, and react for 30min~60min; 2) Add the first batch of urea and dispersant to the reactor, heat to 50℃~70℃, and react for 30min~60min; 3) Add a second batch of urea, organosilicon compound, and deionized water to the reactor and react for 1 to 3 hours; 4) Add flame retardant to the reaction vessel, stir for 30 minutes, adjust the pH value to 7.0~9.0 using a pH adjuster, cool and discharge to obtain organosilicon modified formaldehyde-free amino resin.

2. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, According to the component mass percentage ratio, the organosilicon modified formaldehyde-free amino resin includes 20%~35% glyoxal, 5%~20% melamine, 10%~40% urea, 5%~20% organosilicon compounds, 2%~10% dispersant, and 1%~5% flame retardant, wherein the urea includes primary urea and secondary urea.

3. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, In preparation step 3), the organosilicon compound includes one or more of sodium methylsilicate, hydroxyl-terminated polydimethylsiloxane, vinyltriethoxysilane, and vinyltrimethoxysilane.

4. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, In preparation step 2), the dispersant includes one or more of polyvinyl alcohol, polyethylene glycol, ethylene glycol, glycerol, isopropanol, pentaerythritol, ethanol, and methanol.

5. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, In preparation steps 1) and 4), the pH adjuster is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium silicate, and potassium silicate.

6. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, In preparation step 4), the flame retardant includes one or more of the following: ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, boric acid, and borax.

7. The method for preparing organosilicon-modified formaldehyde-free amino resin as described in claim 1, characterized in that, The mass ratio of the first urea to the second urea is (2~3):

1.

8. The application of the organosilicon-modified formaldehyde-free amino resin prepared by the method for preparing organosilicon-modified formaldehyde-free amino resin according to any one of claims 1 to 7 for the modification of wood.

9. The application of the organosilicon-modified formaldehyde-free amino resin to wood modification as described in claim 8, characterized in that, The modification steps include the following: 1) Obtain logs, air-dry the logs to a moisture content of 60%~20%, and then process the logs into boards; 2) The board is immersed in silicone-modified formaldehyde-free amino resin. The silicone-modified formaldehyde-free amino resin and the board are placed in a vacuum pressurization device. The board is vacuum pressurized and impregnated using the vacuum pressurization device so that the silicone-modified formaldehyde-free amino resin penetrates into the board to achieve the set penetration amount. The vacuum pressurization equipment has a vacuum range of -0.05MPa to -0.1MPa and a pressurization range of 0.6MPa to 2.0MPa for vacuum pressurizing organosilicon-modified formaldehyde-free amino resin-impregnated wood. 3) Remove the board from the silicone-modified formaldehyde-free amino resin, first air-dry the board for 2-3 days, then dry the board at a temperature of 40℃-80℃ until the moisture content of the board is 5%-10%.

10. The application of the organosilicon-modified formaldehyde-free amino resin to wood modification as described in claim 9, characterized in that, The logs are coniferous and broad-leaved wood.

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