Yellowing-resistant barrier type pine wood and preparation method thereof

Abstract

The invention provides yellowing-resistant barrier type pine wood and a preparation method thereof, and relates to the technical field of wood yellowing. Selecting the cross section of pine as a decorative surface, and coating the surface of the decorative surface with an anti-yellowing coating; and the surface of the anti-yellowing coating is coated with a blocking layer, and the anti-yellowing blocking type pine wood is obtained. According to the invention, the cross section is selected as the decorative surface, and the decorative surface is coated with the yellowing-resistant coating, so that an excellent yellowing-resistant effect is obtained, and the obtained pine wood is excellent in yellowing resistance, color stability, water resistance, mildew resistance and size stability.

Description

Technical Field

[0001] The present invention relates to the technical field of wood yellowing, and in particular to yellowing-resistant barrier-type pine wood and a preparation method thereof. Background Art

[0002] Pine, a common wood type used in timber structures, includes larch, Scots pine, and Douglas fir. In timber structures, longitudinal sections (radial or tangential sections) are typically used as decorative surfaces. However, pine wood suffers from several issues, including aging and yellowing, as well as poor water resistance, which can lead to cracking, deformation, and mold and rot. Yellowing reduces the wood's gloss and decorative qualities, while cracking and especially fractures significantly impact the wood's appearance and mechanical strength. Deformation, mold and rot also affect both appearance and usability.

[0003] Existing yellowing resistance technologies primarily utilize bleaching with a mixture of sodium silicate and hydrogen peroxide (e.g., CN202410157073) and the addition of anti-yellowing agents (e.g., 6,7-dimethoxycoumarin and nano-TiO2). Waterproofing and crack prevention primarily involve coating or impregnation to create a physical barrier that isolates moisture exchange (e.g., CN202110395421, CN202010213618), or through chemical reactions with wood components (e.g., CN201910503818). Overall, existing technologies often offer limited functionality. Some chemical treatments rely on toxic and hazardous chemicals, while others are complex processes. Therefore, the development of multifunctional, environmentally friendly treatment technologies is essential. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a yellowing-resistant barrier pine wood and a preparation method thereof, and the obtained pine wood has excellent yellowing resistance, color stability, water resistance, mildew resistance and dimensional stability.

[0005] One of the purposes of the present invention is to provide a method for preparing yellowing-resistant barrier pine wood.

[0006] The second purpose of the present invention is to provide a yellowing-resistant barrier pine wood prepared by the preparation method.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] In a first aspect, the present invention provides a method for preparing yellowing-resistant barrier pine wood, comprising the following steps:

[0009] The cross section of pine wood is selected as the decorative surface, and a yellowing-resistant coating is applied on the surface of the decorative surface; a barrier layer is further applied on the surface of the yellowing-resistant coating to obtain yellowing-resistant barrier pine wood.

[0010] Wood is structurally composed of three sections: transverse, radial, and tangential. A transverse section is a section perpendicular to the trunk's main axis or grain, i.e., the end face or cross section of a tree trunk. A radial section is a section along the trunk's axis, through the pith and parallel to the wood rays or perpendicular to the growth rings. A tangential section is a longitudinal section that does not pass through the pith and follows the wood grain.

[0011] Pine wood structures are usually made of longitudinal sections (i.e. radial sections and tangential sections) when used. For example, the decorative surfaces of pine wood boards are all longitudinal sections. However, the inventors have found that the yellowing properties of different sections of pine wood are significantly different. The longitudinal section of the pine wood itself is more yellowish than the cross section, and the cross section itself is light in color and may turn yellow slightly more easily than the longitudinal section after exposure to sunlight. Through experiments, it was found that the cross section of untreated (uncoated with anti-yellowing coating) pine wood turns slightly more yellow than the longitudinal section after aging. However, the cross section of treated (coated with anti-yellowing coating) pine wood turns less yellow than the longitudinal section after aging. The present invention selects the cross section as the decorative surface and applies the anti-yellowing coating to obtain an excellent anti-yellowing effect.

[0012] Yellowing mainly comes from the yellow oxides generated by substances such as rosin, tannic acid, and lignin under the action of light and oxygen. Rosin, tannic acid, and lignin can react with sodium hydroxide to generate sodium rosinate, sodium tannate, sodium lignin sulfonate, etc., but this treatment method will cause pollution, and if the residues on the surface of the treated pine wood are not completely removed, it will cause problems such as decreased adhesion of the subsequent coating, bubbles, and whitening. Therefore, the present invention gives priority to blocking the effects of light and oxygen, and controls reactions such as photooxidation and cracking of pine wood. Among them, ultraviolet rays (wavelength 280-400nm) can induce bond breakage and free radical generation due to their high energy, which is the main cause of yellowing of pine wood. Therefore, the present invention adopts ultraviolet absorbers (UV1130) and hindered amines (UV292) to control the effect of light.

[0013] There are many types of UV absorbers, but experiments have found that some are difficult to disperse evenly in water, and some have adverse reactions with water-based coatings, such as reacting with water-based polyurethane to produce white non-sticky substances.

[0014] Preferably, the yellowing-resistant coating is obtained by applying a yellowing-resistant paint, which includes the following components: ultraviolet absorber UV1130, light stabilizer UV292, diethylene glycol diethyl ether, deionized water and water-based polyurethane, with a mass ratio of diethylene glycol diethyl ether: UV1130: UV292: deionized water: water-based polyurethane = 3-4: 0.5-1: 0.5-0.8: 3-4: 65-75.

[0015] The preparation method of the yellowing-resistant coating includes: first adding UV1130 and UV292 to diethylene glycol diethyl ether, stirring and dispersing them in advance, then adding deionized water, stirring until transparent, and then mixing them evenly with water-based polyurethane.

[0016] The coating weight of the yellowing-resistant coating can be 140-400g / m 2 .

[0017] In order to further enhance the durability of the pine wood cross section after yellowing resistance treatment, a high barrier waterproof coating is used for waterproof and crack prevention.

[0018] Preferably, the barrier layer is obtained by coating a barrier coating, which includes the following components in mass percentage: 80% to 90% polyvinylidene chloride emulsion, 10% to 20% deionized water, 0.5% to 2% nano-titanium dioxide, 0.05% to 2% emulsifier (fatty alcohol polyoxyethylene ether-9), 0.01% to 0.5% pH regulator (glacial acetic acid), and 0.01% to 0.5% defoaming agent (BYK-204).

[0019] The preparation method of the barrier coating includes:

[0020] Add 20nm rutile nano-titanium dioxide to deionized water, add emulsifier, and disperse it with a high-pressure homogenizer for 10 to 30 minutes to prepare a titanium dioxide slurry; slowly add the slurry to the polyvinylidene chloride emulsion while stirring, with a stirring speed of 300 to 600 r / min and a stirring time of 20 to 30 minutes. Continue to add the defoaming agent while stirring, and adjust the pH value to 3 to 4 with a pH regulator; after all are added, stir for 20 to 30 minutes to form a barrier coating after uniform dispersion.

[0021] The coating weight of barrier coating can be 40-80g / m 2 .

[0022] Furthermore, a water-resistant layer is applied on the surface of the barrier layer, and the water-resistant layer is a two-component water-based emulsion.

[0023] Preferably, the water-resistant layer is formed by applying a water-resistant coating, which includes component A and component B. Component A comprises the following: polycarbonate diol, deionized water, a leveling agent (such as BYK-331), and dipropylene glycol methyl ether. Component B comprises the following: hexamethylene diisocyanate. The mass ratio of polycarbonate diol, deionized water, leveling agent, dipropylene glycol methyl ether, and hexamethylene diisocyanate is: polycarbonate diol: deionized water: leveling agent: dipropylene glycol methyl ether: hexamethylene diisocyanate = 2-3: 5-6: 0.01-0.05: 1-1.5: 0.6-0.8.

[0024] The preparation method of the water-resistant coating comprises: firstly mixing polycarbonate diol with deionized water, a leveling agent and dipropylene glycol methyl ether according to a mass ratio, stirring until transparent, then adding hexamethylene diisocyanate as a curing agent according to a mass ratio, and stirring evenly.

[0025] The coating amount of water-resistant coating can be 80-120g / m 2 .

[0026] The anti-yellowing coating is used as an adhesion reinforcement layer, a high barrier layer is added, and a water-resistant layer can be added if necessary. By controlling the moisture content of the pine wood and the dimensional changes caused by the inflow and outflow of water, cracking of the pine wood and damage to the anti-yellowing coating can be prevented.

[0027] Preferably, in order to ensure the waterproof and crack-proof effect, the pine wood can be pretreated first: the edges can be chamfered or rounded after drying and degreasing. Generally, the moisture content after drying is about 12%, which is determined according to the equilibrium moisture content of the place where the wood is used.

[0028] Preferably, in order to reduce the cost of subsequent waterproofing treatment, the gaps in the decorative surface can be filled with transparent putty first, and the putty can be sanded after drying, and then the yellowing-resistant coating can be applied.

[0029] In a second aspect, the present invention provides a yellowing-resistant barrier pine wood, which is prepared by the above-mentioned preparation method.

[0030] Technical effect:

[0031] This invention addresses the issues of pine wood's propensity to yellowing, cracking, and insufficient water resistance in architectural and decorative applications. By applying a multifunctional coating treatment using a water-based emulsion on cross-sections, this environmentally friendly solution achieves superior yellowing resistance to longitudinal sections, achieving an anti-yellowing efficiency exceeding 89% and a water resistance efficiency as high as 94%. The 24-hour water absorption width expansion rate of the cross-section of the waterproofed sample was only 22% of that of two imported brand products, Group B, and 27% of that of Group C. This method can also be adapted to improve the water resistance and light resistance of other wood species.

[0032] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a photo of the UV accelerated aging test;

[0034] Figure 2 This is a test photo of Example 4;

[0035] Figure 3 is the water absorption of each group of samples in 24 hours;

[0036] Figure 4 (a) Thickness expansion rate, (b) Width expansion rate of each group of specimens;

[0037] Figure 5 This is a photo of the water absorption cross section. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0039] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art.

[0040] Example 1: Color test of different sections of pine wood

[0041] Test method: Obtain the cross section and longitudinal section of the same pine wood and measure the CIE 1976-L * a * b * Chromaticity, test conditions are 10° observer, D65 light source, b * It represents the position of the chromaticity axis from yellow to blue, b * <0, indicating that the color tends to be blue, b * The smaller it is, the more blue the color is; b * >0, indicating a tendency towards yellow, b * The larger it is, the more yellow the color becomes.

[0042] Taking Pinus sylvestris and Larix gmelinii as examples, the b* and standard deviation (SD) of their cross sections and longitudinal sections are shown in Table 1:

[0043] Table 1

[0044] Pinus sylvestris b* SD larch b* SD cross section 19.18 2.07 18.17 1.04 longitudinal section 23.13 1.49 23.63 1.89

[0045] As can be seen from the table, the b* values ​​of the two types of pine wood are both greater than 0, indicating that they are both yellowish; the b* values ​​of the cross sections of the two types of pine wood are both smaller than those of the longitudinal sections, indicating that the longitudinal section of the pine wood itself is more yellowish than the cross section.

[0046] Example 2 Yellowing resistance test of different sections of pine wood

[0047] 1. Preparation method of yellowing-resistant coating:

[0048] The quality ratio of the yellowing-resistant coating formula is as follows: diethylene glycol diethyl ether: UV1130: UV292: deionized water: aliphatic water-based polyurethane (Zhanchen, ZW56207, outdoor use) = 3.27:0.84:0.56:3.27:70. When preparing, first add UV1130 and UV292 to diethylene glycol diethyl ether, stir and disperse in advance, then add deionized water, stir until it becomes transparent, and then mix evenly with the water-based polyurethane.

[0049] In order to improve the uniformity of coating, coating can be done in two times, with the coating amount of each time being 140g / m 2 .

[0050] 2. Test method:

[0051] The cross-cut and quarter-cut boards of Pinus sylvestris and Larch were used as samples, and the anti-yellowing coating was treated according to the above method. Then, the UV accelerated aging (such as Figure 1 Each sample was covered with aluminum foil for comparison and observation. The specific conditions were in accordance with ASTM G154-12a. The lamp used was UVA-340, 15W / m 2 , blackboard temperature 60℃, UV light 8h, then blackboard temperature 50℃, condensation 4h constitute one cycle, accelerated aging 20 cycles.

[0052] The b* values ​​and their standard deviations (SD) after UV accelerated aging are shown in Table 2 below:

[0053] Table 2

[0054] Pinus sylvestris b* SD larch b* SD Yellowing resistance_cross section 20.96 0.70 21.10 0.81 Yellowing resistance_longitudinal section 24.68 1.07 23.49 1.20 Unprocessed_cross section 35.94 0.70 37.46 0.89 Unprocessed_Longitudinal Section 39.24 0.74 39.25 1.61

[0055] As can be seen from the table, after UV-accelerated aging, the b* values ​​for both yellowing-resistant pine samples were smaller on cross-section than on longitudinal sections, as were the values ​​for untreated samples. This demonstrates that using cross-sections as decorative surfaces offers a significant advantage in terms of yellowing resistance. Furthermore, the b* standard deviations for both pine woods after UV-accelerated aging, regardless of whether they had been treated for yellowing resistance, were smaller on cross-section than on longitudinal sections, indicating that the former exhibited better color uniformity.

[0056] The difference Δb* between before and after UV accelerated aging and the anti-yellowing efficiency are shown in Table 3 below:

[0057] Anti-yellowing efficiency = (1-yellowing-resistant sample Δb* / untreated sample Δb*) × 100%.

[0058] Table 3

[0059]

[0060] A Δb* value greater than 0 indicates further yellowing of the pine wood after UV-accelerated aging; larger values ​​indicate more severe yellowing. As can be seen from the table, yellowing of both pine wood types was significantly reduced after anti-yellowing treatment, with anti-yellowing efficiencies ranging from 86% to 89%. The Δb* values ​​for the cross-sections of both treated pine wood types were smaller than those for the longitudinal sections, while those for the untreated cross-sections were slightly larger, demonstrating the effectiveness of the anti-yellowing treatment. Furthermore, due to the high porosity of the cross-section, the actual surface area is larger than that measured macroscopically, resulting in a smaller amount of anti-yellowing coating applied than on the longitudinal section. However, in this case, the anti-yellowing efficiency is still higher than that of the longitudinal section, indicating that the effect is more pronounced when using the cross-section.

[0061] Example 3 Anti-yellowing coating formulation effect test

[0062] Four coatings with different formulations were prepared by adding only one of UV292 and UV1130, adding both UV292 and UV1130 (pre-dispersion method and other formulations were the same as in Example 2) to the waterborne polyurethane, and coating the pine boards with the four coatings. After drying, the UV accelerated aging test was performed using the same method as in Example 2.

[0063] Measure Δb* before and after aging and calculate the total color difference ΔE*.

[0064] ΔL * , Δa * , Δb * They are the differences of three L*, a*, and b* respectively.

[0065] The component effect was measured by the reduction in total color difference after adding a component: Component effect = ΔE* of the unadded group minus ΔE* of the added group. A larger effect value indicates greater color stability. The results are shown in Table 4.

[0066] Table 4

[0067] coating Δb* ΔE* Component effect Add only UV292 8.90 16.37 0.37 Add only UV1130 -2.10 7.42 9.32 Add UV292+UV1130 at the same time 1.99 3.93 12.81 No addition 11.24 16.74 -

[0068] As shown in Table 4, after adding the components, the absolute value of the change in the yellow-blue index Δb* was smaller than that of the group without addition. The change in the yellow-blue index was minimized when UV292 and UV1130 were added simultaneously. From the perspective of total color difference ΔE*, the total color difference was minimized when both components were added simultaneously. Assuming the effects of each component are linearly superimposed, it can be inferred that, relative to the group without addition, the total color difference of the sample with UV292 added decreased by 0.37 after UV-accelerated aging. With UV1130, the total color difference decreased by 9.32. With simultaneous addition, the total color difference decreased by 12.81, which is greater than 0.37 + 9.32 = 9.69. This indicates that UV292 and UV1130 have a synergistic effect, making their combined use superior to that of either alone.

[0069] Example 4 Waterproof Effect Test

[0070] The cross section of 60mm (L fiber direction, height) × 50mm × 170mm leaf pine glued wood was used as the specimen ( Figure 2 , the shooting surface is the cross section of water absorption), each test group is coated with different coatings:

[0071] Test Group A: Three-layer composite coating: Adhesion layer 400g / m 2 + Barrier layer 80g / m 2 +Water-resistant layer 120g / m 2 ;

[0072] The adhesion layer is water-based polyurethane (i.e., the yellowing-resistant coating in Example 2);

[0073] The barrier layer is a polyvinylidene chloride emulsion, composed of 85% polyvinylidene chloride emulsion (Dongguan Kadar Plastics), 12% deionized water, 1% nano-titanium dioxide, 1% emulsifier (fatty alcohol polyoxyethylene ether-9), 0.5% pH adjuster (glacial acetic acid), and 0.5% defoamer (BYK-204). 20nm rutile nano-titanium dioxide was added to deionized water and the emulsifier, and dispersed in a high-pressure homogenizer for 30 minutes to form a titanium dioxide slurry. The slurry was then slowly added to the polyvinylidene chloride emulsion while stirring at 600 rpm for 20 minutes. The defoamer was then added while stirring, and the pH was adjusted to 3-4 using a pH adjuster. After all the ingredients were added, the mixture was stirred for 30 minutes to achieve uniform dispersion.

[0074] The water-resistant layer is a two-component aqueous emulsion. First, polycarbonate diol (Asahi Kasei PCDX-228) is mixed with pure water, BYK-331, and dipropylene glycol methyl ether in a mass ratio of 2.44:5.36:0.02:1.05, stirred until transparent, and then 0.71 parts of hexamethylene diisocyanate are added as a curing agent according to the mass ratio and stirred evenly.

[0075] Comparison Group B: Primer and topcoat of an imported brand of water-based paint S (primer 400g / m 2 +Topcoat 200g / m 2 );

[0076] Comparison Group C: an imported brand of end-capping anti-cracking agent T0 (600g / m 2 );

[0077] The cross section was waterproofed and the four adjacent longitudinal sections were also waterproofed for 2 cm. A group of untreated samples D was also set up as a control. All samples were dried naturally and then dried in an oven at 50°C for 2 hours. After equilibration for more than 1 week, a cross-section water absorption test was conducted with a water depth of 5 mm. The mass before and after water absorption was measured and the 24-hour water absorption was calculated as follows: Figure 3 shown.

[0078] from Figure 3 Water absorption by the larch cross-section was significantly reduced after waterproofing treatment, with Group A showing the lowest water absorption. Group C absorbed 11.89% more water than Group A, and Group B absorbed 35.80% more. Calculated according to ASTM D 5401, Group A's waterproofing efficiency was 84.45%. The test also revealed no changes in appearance after immersion in water. Group B exhibited whitening at the edges and corners, but the paint film showed no bubbling or shedding. Group C also exhibited slight whitening at the edges and corners, but the paint film also showed no bubbling or shedding.

[0079] From the perspective of dimensional change, the dimensional change is significantly reduced after waterproofing treatment. Figure 4As can be seen, the expansion rate in the thickness direction is much smaller than that in the width direction. The sample treated with coating A proposed by the present invention has the smallest dimensional change, with its width expansion rate being only 22% of that of group B, 27% of that of group C, and 5% of that of the control.

[0080] In the experiment, due to the large number of gaps in the cross section of pine wood, which absorbed more paint, it was improved to fill it with putty before waterproofing. For example, if transparent putty is used, the amount is 300g / m 2 At this time, the amount of adhesive layer can be reduced to 150g / m 2 , the waterproof efficiency can reach more than 94%.

[0081] Example 5 Comparative test of hydrophobic layer and water-resistant layer

[0082] Using Pinus sylvestris as the specimen, the longitudinal section was first treated according to Group A, then cut into blocks, one of which was painted using Group A and Group E methods respectively:

[0083] Test Group A: Three-layer composite coating: Adhesion layer 400g / m 2 + Barrier layer (water-resistant layer) 80g / m 2 +Water-resistant layer 120g / m 2 (Same as Example 4);

[0084] Test Group E: Three-layer composite coating: Adhesion layer 400g / m 2 +Hydrophobic layer 80g / m 2 +Hydrophobic layer 120g / m 2 , where the hydrophobic layer is fluorine-containing emulsion AG-E7800.

[0085] To ensure the uniformity of moisture content of each sample, all samples were first dried in a 110°C oven for 15 minutes, then equilibrated at room temperature for more than one week. After weighing, the painted cross-section was immersed in 5mm deep water for 5 days and weighed again. The water absorption of the two groups was calculated.

[0086] The test results show that the water absorption of group A is significantly less than that of group E. The water absorption of group A is 0.9761g, with a standard deviation of 0.0469g, while that of group E is 2.4419g, with a standard deviation of 0.1458g. Figure 5 It can be seen that the coating of group E (first row) turned white, while no obvious abnormality was observed in group A (second row).

[0087] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. A method for preparing yellowing-resistant barrier pine wood, characterized in that: The following steps are involved: The cross section of pine wood is selected as the decorative surface, and the surface of the decorative surface is coated with a yellowing-resistant coating; A barrier layer is applied on the surface of the yellowing-resistant coating to obtain yellowing-resistant barrier pine wood.

2. The preparation method according to claim 1, characterized in that The yellowing-resistant coating is obtained by applying a yellowing-resistant paint, which includes the following components: ultraviolet absorber UV1130, light stabilizer UV292, diethylene glycol diethyl ether, deionized water and water-based polyurethane, with a mass ratio of diethylene glycol diethyl ether: UV1130: UV292: deionized water: water-based polyurethane = 3-4: 0.5-1: 0.5-0.8: 3-4: 65-75.

3. The preparation method according to claim 2, characterized in that The preparation method of the yellowing-resistant coating comprises: firstly adding UV1130 and UV292 to diethylene glycol diethyl ether, stirring and dispersing them in advance, then adding deionized water, stirring until transparent, and then mixing with waterborne polyurethane uniformly; The coating weight of the yellowing-resistant coating is 140-400g / m 2 .

4. The preparation method according to claim 1, characterized in that The barrier layer is obtained by coating a barrier coating, which includes the following components in mass percentage: 80% to 90% polyvinylidene chloride emulsion, 10% to 20% deionized water, 0.5% to 2% nano titanium dioxide, 0.05% to 2% emulsifier, 0.01% to 0.5% pH regulator, and 0.01% to 0.5% defoaming agent.

5. The preparation method according to claim 4, characterized in that The preparation method of the barrier coating includes: Add 20nm rutile nano-titanium dioxide to deionized water, add an emulsifier, and disperse it with a high-pressure homogenizer for 10 to 30 minutes to prepare a titanium dioxide slurry; slowly add the slurry to the polyvinylidene chloride emulsion while stirring at a stirring speed of 300 to 600 r / min for 20 to 30 minutes, continue to add the defoaming agent while stirring, and adjust the pH value to 3 to 4 with a pH regulator; after all are added, stir for 20 to 30 minutes to form a barrier coating after uniform dispersion; The coating amount of barrier coating is 40-80g / m 2 .

6. The preparation method according to claim 1, characterized in that Apply a water-resistant layer on the surface of the barrier layer; The water-resistant layer is obtained by coating a water-resistant coating, which includes component A and component B. Component A includes the following components: polycarbonate diol, deionized water, a leveling agent, and dipropylene glycol methyl ether; component B includes the following components: hexamethylene diisocyanate; the mass ratio of polycarbonate diol: deionized water: leveling agent: dipropylene glycol methyl ether: hexamethylene diisocyanate is 2-3: 5-6: 0.01-0.05: 1-1.5: 0.6-0.

8.

7. The preparation method according to claim 6, characterized in that The preparation method of the water-resistant coating comprises: firstly mixing polycarbonate diol with deionized water, a leveling agent, and dipropylene glycol methyl ether according to a mass ratio, stirring until transparent, then adding hexamethylene diisocyanate according to a mass ratio, and stirring evenly; The coating amount of water-resistant coating is 80-120g / m 2 .

8. The preparation method according to claim 1, characterized in that The pine wood is first dried and degreased, and then coated with a yellowing-resistant coating.

9. The preparation method according to claim 1, characterized in that First fill the gaps in the decorative surface with transparent putty, sand it after the putty dries, and then apply the yellowing-resistant coating.

10. A yellowing-resistant barrier pine wood, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

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