Method for constructing alkali-resistant organic / organosilicon hybrid resin coating layer on wood surface in situ based on reactive hybridization

Abstract

The application discloses a method for constructing alkali-resistant organic / silicone hybrid resin coating on wood surface in situ based on reactive hybridization, which comprises the following steps: coating a modified solution composed of divinylbenzene, polymethyl hydrogen siloxane and a catalyst on the wood surface under preset conditions, and then curing under normal temperature and pressure to realize the construction of alkali-resistant organic / silicone hybrid resin coating on the wood surface in situ. The application innovatively adopts the reactive hybridization technology, and under the action of Kastredt catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, commonly known as "platinum gold water" in industry), constructs the organic / silicone hybrid resin coating on the wood surface in situ based on the ultrafast addition reaction between the vinyl of divinylbenzene (the skeleton structure of organic resin) and the -Si-H group of polymethyl hydrogen siloxane (the skeleton structure of silicone resin) under normal temperature and pressure. The method has the advantages of simple formula components and simple coating process; meanwhile, the application introduces the organic resin into the silicone resin through the reactive hybridization technology, effectively solves the problem that the pure silicone resin coating is not resistant to alkali while retaining the excellent hydrophobicity, waterproofness, transparency, wear resistance and ultraviolet resistance of the silicone resin coating, and expands the application field of the silicone resin coating.

Description

Technical Field

[0001] This invention relates to the field of wood protection technology, and in particular to a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on the surface of wood based on reactive hybridization. Background Technology

[0002] Wood is a renewable biomass material, widely used in construction, furniture, and decoration due to its lightweight and high specific strength. However, wood's hydrophilicity and porosity make it prone to absorbing moisture from the environment, leading to problems such as cracking, mold, and decay. Wood mold and decay are carbon-emitting processes that should be avoided as much as possible; simultaneously, replacing deteriorated wood with new timber requires deforestation, weakening the carbon sequestration capacity of forests. Therefore, wood conservation plays a positive role in my country's goals of achieving "carbon peaking" and "carbon neutrality."

[0003] Since ancient times, painting has been one of the primary methods of wood protection. Traditional coatings fall into two categories: natural oils and synthetic polymers. The framework structure of traditional coatings is mainly CC or CO, which have relatively low bond energies and are easily degraded under ultraviolet radiation, resulting in a short service life for outdoor use. Organosilicon, on the other hand, has a Si-O framework with bond energies far higher than CC or CO, exhibiting excellent UV resistance and significantly extending the outdoor service life of the coating.

[0004] Literature (Forest Products Industry. 2020, 57(11), 65-68) describes the use of organoalkoxysilane coupling agents to treat wood, which significantly improves the water resistance and decay resistance of wood. Literature (Cellulose (2021) 28: 3745-3758) describes the use of addition-type organosilicon rubber and commercially available silica nanoparticles (fumed silica) to construct a superhydrophobic coating on the surface of wood, which significantly improves the water resistance of wood and endows it with self-cleaning properties; at the same time, the research results also show that the coating has good UV resistance. Although organosilicon modification can significantly improve the water resistance of wood and the coating has outstanding UV resistance, the Si-O skeleton structure of organosilicon is not alkali resistant; the organosilicon coating on the wood surface is dissolved after immersion in NaOH aqueous solution, losing its protective effect. Therefore, seeking a method to improve the alkali resistance of organosilicon coatings is crucial for expanding the application range of wood. Summary of the Invention

[0005] In view of this, the object of the present invention is to propose a method for constructing an alkali-resistant coating in situ on the surface of wood by hybridizing organic resin and organosilicon resin.

[0006] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows:

[0007] A method for in-situ constructing alkali-resistant organic / organosilicon hybrid resin coatings on wood surfaces based on reactive hybridization includes:

[0008] A modified liquid consisting of divinylbenzene, polymethylhydrosiloxane, and Kastredt catalyst is applied to the wood surface under preset conditions; then cured at room temperature to complete the construction of an alkali-resistant organic / organosilicon hybrid resin coating on the wood surface.

[0009] As one possible implementation method, further, in the modified liquid of this scheme, the mass ratio of polymethylhydrosiloxane, divinylbenzene and Kastredt catalyst is (0.1-10):1:(0.01-0.1);

[0010] As a preferred embodiment, the preferred method is to apply the modified liquid to the wood surface at a coating amount of 50-600 g / m². 2 .

[0011] As a preferred implementation method, the curing conditions described in this solution can preferably be either at room temperature or under heating conditions. The purpose of heating is solely to accelerate curing.

[0012] As a preferred embodiment, the catalyst described in this scheme is preferably a Kastredt catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, commonly known in industry as "platinum water"), which can catalyze the chemical reaction between the silane-hydrogen bonds on the polymethylhydrosiloxane chain and the vinyl groups in the divinylbenzene structure at room temperature.

[0013] The key technology of this invention is to construct an alkali-resistant organosilicon / organo-hybrid resin coating in situ on the wood surface through reactive hybridization technology. The main components of the modifying liquid for constructing the coating are divinylbenzene, polymethylhydrosiloxane, and Kastredt catalyst. Divinylbenzene and polymethylhydrosiloxane undergo an addition reaction under the catalysis of Kastredt catalyst to form an organosilicon / organo-hybrid resin coating on the wood surface. Simultaneously, under the action of Kastredt catalyst, polymethylhydrosiloxane in the modifying liquid can undergo a dehydrogenation reaction with the hydroxyl groups on the wood surface, thereby in situ reacting the organosilicon / organo-hybrid resin coating onto the wood surface through Si-OC covalent bonds.

[0014] The hybridization principle of this scheme is as follows: Figure 1The above describes an addition reaction between the -Si-H group of polymethylhydrosiloxane and the vinyl group of divinylbenzene. Polymethylhydrosiloxane imparts a silicone resin backbone to the hybrid resin, while divinylbenzene imparts an organic resin backbone. The silicone resin backbone gives the hybrid coating good water resistance and UV resistance; the organic resin backbone also imparts good alkali resistance. When the hybrid coating is immersed in an alkaline solution, although the silicone backbone is dissolved by the alkali, a hydrophobic organic resin backbone remains, continuing to resist alkali erosion. This is the principle behind the alkali resistance of the hybrid coating designed in this invention. Wood coated with the silicone / organic hybrid coating was immersed in a NaOH aqueous solution with pH=13 for 24 hours, and the water contact angle of the hybrid coating still reached 100°, indicating its excellent alkali resistance. The principle of the alkali resistance of the silicone / organic hybrid resin coating was demonstrated by scanning electron microscopy, as shown in the attached figure. Figure 2 As shown, the surface of the wood sample coated with an organosilicon / organic hybrid coating after being immersed in a NaOH aqueous solution with pH=13 for 24 hours exhibits a loose and porous structure. This structure is the organic resin skeleton left after the organosilicon resin skeleton in the hybrid coating is dissolved.

[0015] By adopting the above technical solution, the present invention has the following beneficial effects compared with the traditional technology:

[0016] (1) The present invention innovatively adopts a reactive hybrid technology to construct an alkali-resistant organic / organosilicon hybrid resin coating on the surface of wood in situ. The preparation of the modified liquid and the construction of the coating on the wood surface are simple and the conditions are mild (room temperature and pressure).

[0017] (2) The present invention uses reactive hybrid technology to construct an alkali-resistant organic / organosilicon hybrid resin coating on the surface of wood in situ, which combines the advantages of organosilicon resin and organic resin, and has the weather resistance, excellent water resistance and wear resistance of organosilicon resin and the alkali resistance of organic resin. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the chemical principle of the method of the present invention. The vinyl group of the raw material divinylbenzene and the -Si-H bond of polymethylhydrosiloxane undergo an addition reaction under the action of Kastredt catalyst, and are cured in situ on the wood surface to obtain an organosilicon / organic hybrid resin coating.

[0020] Figure 2 This is a scanning electron microscope image of wood coated with an organosilicon / organic hybrid resin according to the present invention after soaking in a NaOH aqueous solution with pH=13 for 24 hours. Figure 2 In the figure, Figure (a) is magnified 5,000 times, and Figure (b) is magnified 20,000 times. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Combination Figure 1 As shown, the present invention provides a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on the surface of wood based on reactive hybridization, which includes the following steps:

[0023] (1) Preparation of modified solution: Polymethylhydrosiloxane, divinylbenzene and Kastredt catalyst are mixed evenly at a mass ratio of (0.1-10):1:(0.01-0.1) to obtain modified solution;

[0024] (2) Wood modification: The modification liquid is applied to the surface of the wood by brushing or spraying, and the modified wood is cured at room temperature or under heating conditions. The heating only accelerates the curing process.

[0025] The catalyst mentioned in step (1) of this scheme is a Kastredt catalyst that can catalyze the chemical reaction between the silane-hydrogen bonds on the polymethylhydrosiloxane chain and the vinyl group in the divinylbenzene structure at room temperature. It is a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, which is commonly known in industry as "platinum water".

[0026] The coating amount of the modified liquid mentioned in step (2) of this scheme is 50-600g / m. 2 .

[0027] The present invention will be further illustrated below with reference to multiple embodiments and comparative examples:

[0028] Example 1

[0029] This embodiment describes a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, which includes:

[0030] (1) Preparation of modified liquid: Add 10g polymethylhydrosiloxane, 10g divinyl and 0.1g catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, with a platinum content of 3000ppm) to a container and stir to mix evenly.

[0031] (2) Coating construction and curing: A spray gun is used to spray the modified liquid onto the surface of the wood block. The spraying amount of the modified liquid is 80g / m². 2 Cured at room temperature.

[0032] (3) The water resistance and alkali resistance of the modified wood in this embodiment were tested.

[0033] Performance testing

[0034] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1, respectively. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 17.8%.

[0035] Alkali resistance test: The modified wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results show that, in this embodiment, the water contact angle of the wood surface coating was 98° after 24 hours in a NaOH aqueous solution with pH=13.

[0036] Example 2

[0037] This embodiment describes a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, which includes:

[0038] (1) Preparation of modified liquid: Add 10g polymethylhydrosiloxane, 5g divinyl and 0.15g catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, with a platinum content of 3000ppm) to a container and stir to mix evenly.

[0039] (2) Coating construction and curing: A spray gun is used to spray the modified liquid onto the surface of the wood block. The spraying amount of the modified liquid is 120g / m². 2 Cured at room temperature.

[0040] (3) The water resistance and alkali resistance of the modified wood in this embodiment were tested.

[0041] Performance testing

[0042] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 16.5%.

[0043] Alkali resistance test: The modified wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results show that, in this embodiment, the water contact angle of the wood surface coating was 98.4° after 24 hours in a NaOH aqueous solution with pH=13.

[0044] Example 3

[0045] This embodiment describes a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, which includes:

[0046] (1) Preparation of modified liquid: Add 15g polymethylhydrosiloxane, 5g divinyl and 0.18g catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with a platinum content of 3000ppm) to a container and stir to mix evenly.

[0047] (2) Coating construction and curing: A spray gun is used to spray the modified liquid onto the surface of the wood block. The spraying amount of the modified liquid is 250g / m². 2 Cured at room temperature.

[0048] (3) The water resistance and alkali resistance of the modified wood in this embodiment were tested.

[0049] Performance testing

[0050] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1, respectively. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 15.3%.

[0051] Alkali resistance test: The modified wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results show that, in this embodiment, the water contact angle of the wood surface coating was 98.1° after 24 hours in a NaOH aqueous solution with pH=13.

[0052] Example 4

[0053] This embodiment describes a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, which includes:

[0054] (1) Preparation of modified liquid: Add 20g polymethylhydrosiloxane, 5g divinyl and 0.25g catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with a platinum content of 3000ppm) to a container and stir to mix evenly.

[0055] (2) Coating construction and curing: The modifier liquid was applied to the surface of the wood block using a brush, with a coating amount of 330 g / m². 2 Cured at room temperature.

[0056] (3) The water resistance and alkali resistance of the modified wood in this embodiment were tested.

[0057] Performance testing

[0058] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1, respectively. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 15.6%.

[0059] Alkali resistance test: The modified wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results show that, in this embodiment, the water contact angle of the wood surface coating was 99.2° after 24 hours in a NaOH aqueous solution with pH=13.

[0060] Example 5

[0061] This embodiment describes a method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, which includes:

[0062] (1) Preparation of modified liquid: Add 32g polymethylhydrosiloxane, 5g divinyl and 0.5g catalyst (a complex of chloroplatinic acid and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, with a platinum content of 3000ppm) to a container and stir to mix evenly.

[0063] (2) Coating construction and curing: The modifier liquid was applied to the surface of the wood block using a brush, with a coating amount of 550 g / m². 2 Cured at room temperature.

[0064] (3) The water resistance and alkali resistance of the modified wood in this embodiment were tested.

[0065] Performance testing

[0066] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1, respectively. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 15.3%.

[0067] Alkali resistance test: The modified wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results show that, in this embodiment, the water contact angle of the wood surface coating was 100.1° after 24 hours in a NaOH aqueous solution with pH=13.

[0068] Comparative Example 1

[0069] This comparative example uses dried wood.

[0070] Water resistance and alkali resistance tests were conducted on the wood used in this comparative example.

[0071] Performance testing

[0072] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 105.7%.

[0073] Alkali resistance test: The wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results showed that the NaOH aqueous solution darkened in color, indicating that lignin and other substances in the wood were dissolved by the NaOH. In this comparative example, the water contact angle of the wood surface coating was 12.1° after 24 hours in a NaOH aqueous solution with pH=13.

[0074] Comparative Example 2

[0075] A silicone resin modification solution was prepared by uniformly mixing 10g of polymethylhydrosiloxane, 2g of tetramethyltetravinylcyclotetrasiloxane, and 0.2g of Kastredt catalyst. The modification solution was then sprayed onto the surface of the wood block using a spray gun at a rate of 200g / m². 2 It cures naturally at room temperature, forming an organosilicon resin coating on the wood surface.

[0076] Performance testing

[0077] Water resistance test: The wood was completely immersed in distilled water for 24 hours. The masses of the wood before and after immersion were measured as m0 and m1. The water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 21.3%.

[0078] Alkali resistance test: The wood was immersed in a NaOH aqueous solution with pH=13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results showed that when the wood coated with silicone resin was immersed in the NaOH aqueous solution, the solution turned pale yellow within 10 minutes, indicating that the silicone resin coating on the wood surface was quickly dissolved by the NaOH, further leading to NaOH erosion of the wood. In this comparative example, the modified wood had a water contact angle of 12.5° after 24 hours in a NaOH aqueous solution with pH=13.

[0079] Comparative Example 3

[0080] A silicone rubber modification solution was prepared by uniformly mixing 5g of polymethylhydrosiloxane with a hydrogen content of 0.2%, 15g of vinyl-terminated silicone oil with a viscosity of 1000 cs, and 0.1g of Kastredt catalyst. The modification solution was then applied to the surface of a wood block using a brush, with a coating thickness of 300g / m². 2 It cures naturally at room temperature, forming an organosilicon rubber coating on the wood surface.

[0081] Performance testing

[0082] Water resistance test: The modified wood was completely immersed in distilled water for 24 hours. The masses m0 and m1 of the wood before and after immersion were weighed, and the water absorption rate of the wood after 24 hours was calculated according to the formula (water absorption rate = 100% × (m1 - m0) / m0). The test results show that the water absorption rate of the modified wood in this embodiment is 24.6%.

[0083] Alkali resistance test: Modified wood was immersed in a NaOH aqueous solution at pH 13 for 24 hours, then rinsed three times with distilled water. The wood was then dried, and the water contact angle of the wood surface was measured. The test results showed that, similarly, when wood coated with silicone rubber was immersed in NaOH aqueous solution, the NaOH solution turned pale yellow within 10 minutes, indicating that the silicone rubber coating on the wood surface was quickly dissolved by NaOH, further leading to NaOH erosion of the wood. In this comparative example, the modified wood surface coating had a water contact angle of 13.8° after 24 hours in a NaOH aqueous solution at pH 13.

[0084] A comparative analysis of the above embodiments and comparative examples shows that the advantages of the organosilicon resin coating constructed on the wood surface by the present invention are as follows: (1) Comparing Examples 1-5 and Comparative Example 1, the organosilicon / organic hybrid resin coating constructed on the wood surface by the present invention has excellent water resistance, and the water absorption rate of the wood coated with the organosilicon / organic hybrid resin coating is significantly reduced from 105.7% to about 15%. (2) Comparing Examples 1-5 and Comparative Examples 2 and 3, the organosilicon / organic hybrid resin coating constructed on the wood surface by the present invention has excellent alkali resistance compared with pure organosilicon resin coating and pure organosilicon rubber coating. This is the most important problem to be solved by the present invention, namely, introducing organic resin into organosilicon resin through reactive hybridization technology to endow the organosilicon resin coating with excellent alkali resistance.

[0085] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for in-situ constructing an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization, characterized in that, A modified liquid consisting of divinylbenzene, polymethylhydrosiloxane and Kastredt catalyst is coated on the surface of wood according to preset conditions, and then cured; wherein the mass ratio of polymethylhydrosiloxane, divinylbenzene and Kastredt catalyst is (0.1-10):1:(0.01-0.1).

2. The method for in-situ construction of an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization as described in claim 1, characterized in that, The coating amount of the wood surface modification liquid is 50-600 g / m². 2 .

3. The method for in-situ construction of an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization as described in claim 1, characterized in that, The curing process is performed at room temperature or under heating conditions.

4. The method for in-situ construction of an alkali-resistant organic / organosilicon hybrid resin coating on a wood surface based on reactive hybridization as described in claim 1, characterized in that, The catalyst is a Kastredt catalyst that can catalyze the chemical reaction between the silane bonds on the polymethylhydrosiloxane chain and the vinyl groups in the divinylbenzene structure.

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