Preparation method of organic silicon modified super-hydrophobic wood

Abstract

The invention relates to the technical field of wood modification, in particular to a preparation method of organic silicon modified super-hydrophobic wood. The preparation method of the organic silicon modified super-hydrophobic wood comprises the following steps: preparing hydrophobic silicon dioxide sol, preparing organic silicon modified liquid, dipping the wood in the hydrophobic silicon dioxide sol for multiple times, spraying the organic silicon modified liquid on the surface of a wood matrix, and curing at normal temperature. According to the organosilicone modified super-hydrophobic wood, a multifunctional hydrophobic coating is constructed on the surface of the wood by adopting a dip coating process, and the organosilicone modified super-hydrophobic wood has the advantages of simple equipment and preparation process, low energy consumption, short reaction period, high curing efficiency, mostly non-toxic modifier and the like, and is suitable for being applied to preparation of large-area hydrophobic / super-hydrophobic wood.

Description

Technical Field

[0001] The present invention relates to the technical field of wood modification, and particularly relates to a preparation method of organosilicon-modified superhydrophobic wood. Background Art

[0002] As a natural renewable and environmentally friendly engineering material, wood is widely used in fields such as home furnishings and wooden structure buildings. However, due to the nature of wood itself, it is prone to phenomena such as mildew and cracking. In order to reduce defects such as discoloration, deformation, and decay caused by excessive moisture absorption during the use of wood, extend the service life of wood, improve the utilization rate of wood, and expand the application fields of wood, functional modification treatment of the wood surface is an effective means to enhance its performance and extend its service life.

[0003] In recent years, by introducing hydrophobic groups on the wood surface or constructing hydrophobic or superhydrophobic coatings on its surface, the waterproof performance of wood has been improved. Traditional hydrophobic modification of wood mostly uses physical, chemical, or physical-chemical combined methods, including acetylation treatment, resin and oil treatment, etc. Most of the processes involved in these modification methods are relatively cumbersome and require a large amount of reagents, increasing the cost of wood modification treatment.

[0004] Patent technical literature CN107022279B discloses a preparation method of a highly transparent, wear-resistant, and superhydrophobic composite coating. The wood coating obtained by this invention has excellent hydrophobicity and transparency, and the preparation method is simple, environmentally friendly, and low-cost, suitable for the surfaces of materials such as glass, stone, ceramics, wood, and metal, with broad application prospects; patent technical literature CN116790185B discloses a method and application for constructing a superhydrophobic coating on the wood surface based on layer-by-layer self-assembly. The preparation method of the wood with a superhydrophobic coating of this invention is simple, the reaction conditions are easy to achieve, and the raw materials used in the preparation are all industrial products with low prices; at the same time, the prepared superhydrophobic wood has good abrasion resistance, giving greater practical application significance to the wood.

[0005] However, with the increasing demand for wood, higher requirements are put forward for its performance. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to propose a preparation method of organosilicon-modified superhydrophobic wood to provide a modified wood with high hydrophobicity, high alkali resistance, and high weather resistance.

[0007] Based on the above purpose, the present invention provides a preparation method of organosilicon-modified superhydrophobic wood, including the following steps: (1) Prepare hydrophobic silica sol; (2) Prepare organosilicon modification liquid; (3) Dry the wood at 100 °C for 5 h, then immerse the wood in a hydrophobic silica sol, dry at room temperature for 10 min, repeat 2 - 3 times, then spray the silicone modification liquid on the wood surface and cure at room temperature to obtain silicone-modified superhydrophobic wood; The preparation steps of the silicone modification liquid described in step (2) are as follows: S1: Disperse Al2O3 nanoparticles in toluene, add triisostearoyl titanate isopropyl ester, and react under magnetic stirring at 75 - 80 °C for 6 - 7 h under nitrogen protection, centrifuge, wash 3 times with toluene, and dry to obtain hydrophobized Al2O3 nanoparticles; S2: Redisperse the hydrophobized Al2O3 nanoparticles in toluene, add 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10 - heptadecafluorodecyltrimethoxysilane, and react under stirring at 50 - 60 °C for 4 h, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; S3: Stir and mix the modified Al2O3 nanoparticles, polymethylhydrosiloxane, organopolysilazane, divinylbenzene, Kastredt catalyst, and n - hexane evenly to obtain a modification liquid; The dosage ratio of the Al2O3 nanoparticles, toluene, and triisostearoyl titanate isopropyl ester described in step S1 is 5 - 8 g:100 - 200 ml:1.5 - 2 g; The dosage ratio of the hydrophobized Al2O3 nanoparticles, toluene, and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10 - heptadecafluorodecyltrimethoxysilane described in step S2 is 5 - 7 g:100 - 200 ml:2 - 3 g; The dosage ratio of the modified Al2O3 nanoparticles, polymethylhydrosiloxane, organopolysilazane, divinylbenzene, Kastredt catalyst, and n - hexane described in step S3 is 3 - 5 g:10 - 15 g:5 - 10 g:5 - 10 g:0.15 - 0.2 g:70 - 80 ml.

[0008] Preferably, the preparation steps of the hydrophobic silica sol described in step (1) are as follows: Mix tetraethyl orthosilicate and absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixed solution of ammonia water and deionized water, maintain reflux stirring at 60 °C for 2 - 3 h, and gradually add methyltriethoxysilane, and continue stirring for 1 - 2 h to obtain a hydrophobic nano - silica sol; Preferably, the dosage ratio of tetraethyl orthosilicate, absolute ethanol, ammonia water, deionized water, and methyltriethoxysilane is 12.4 - 37.2 ml:97.2 - 291.6 ml:7.8 - 23.37 ml:1 - 10 ml:5.5 - 16.6 ml.

[0009] Preferably, the spraying amount of the silicone modification liquid in step (3) is 80 - 120 g / m 2 .

[0010] Advantages of the present invention: By adding nano-aluminum oxide particles, on the one hand, the particles themselves have certain alkali resistance and weather resistance, which can significantly improve the alkali resistance and weather resistance of the modified wood. On the other hand, they exist in the internal network of the surface coating, avoiding the risk of agglomeration, and their uniform distribution in the coating can further enhance the mechanical properties and hydrophobic properties of the modified wood.

[0011] In the present invention, graft modification is carried out on the surface of alumina nanoparticles in a gradient manner, which can not only form a denser hydrophobic barrier to further reduce water penetration under capillary action, but also the gradient structure can further hinder water penetration. On the other hand, the gradient design also improves the weather resistance and alkali resistance of the modified wood. Specific embodiments

[0012] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. Embodiment

[0013] (1) Mix 12.4 ml of tetraethyl orthosilicate with 97.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 7.8 - 23.3 ml of ammonia water and 1 ml of deionized water, maintain reflux stirring at 60 °C for 2 h, and gradually add 5.5 ml of methyltriethoxysilane. After continuing to stir for 1 h, a hydrophobic nano-silica sol is obtained; (2) Disperse 5 g of Al2O3 nanoparticles in 100 ml of toluene, add 1.5 g of isopropyl triisostearoyl titanate, react under nitrogen protection with magnetic stirring at 75 °C for 6 - 7 h, centrifuge, wash with toluene three times, and dry to obtain hydrophobized Al2O3 nanoparticles; (3) Redisperse 5 g of hydrophobized Al2O3 nanoparticles in 100 ml of toluene, add 2 g of heptadecafluorodecyltrimethoxysilane, stir and react at 50 °C for 4 h, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; (4) Stir and mix 3 g of modified Al2O3 nanoparticles, 10 g of polymethylhydrosiloxane, 5 g of organopolysilazane, 5 g of divinylbenzene, 0.15 g of Kastredt catalyst and 70 ml of n-hexane uniformly to obtain a modified liquid; (5) Immerse the wood in the hydrophobic silica sol, dry at room temperature for 10 min, repeat twice, and then spray the modified liquid by spraying, with a spraying amount of 120 g / m 2 , and cure at room temperature. Embodiment

[0014] (1) Mix 24.8 ml of tetraethyl orthosilicate with 197.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 15.6 ml of ammonia water and 5 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, and gradually add 11 ml of methyltriethoxysilane dropwise, continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Disperse 7 g of Al2O3 nanoparticles in 150 ml of toluene, add 1.8 g of isopropyl triisostearoyl titanate, react under nitrogen protection and magnetic stirring at 78 °C for 7 h, centrifuge, wash with toluene 3 times, and dry to obtain hydrophobized Al2O3 nanoparticles; (3) Redisperse 6 g of hydrophobized Al2O3 nanoparticles in 100 ml of toluene, add 2.5 g of heptadecafluorodecyltrimethoxysilane, stir and react at 55 °C for 4 h, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; (4) Mix 4 g of modified Al2O3 nanoparticles, 13 g of polymethylhydrosiloxane, 8 g of organopolysilazane, 5 - 108 g of divinylbenzene, 0.18 g of Kastredt catalyst and 75 ml of n-hexane, stir and mix evenly to obtain a modified liquid; (5) Immerse the wood in the hydrophobic silica sol, dry at room temperature for 10 min, repeat twice, then spray the modified liquid by spraying, and the spraying amount is 120 g / m 2 , and cure at room temperature. Example

[0015] (1) Mix 37.2 ml of tetraethyl orthosilicate with 291.6 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 23.37 ml of ammonia water and 10 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, and gradually add 16.6 ml of methyltriethoxysilane dropwise, continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Disperse 8 g of Al2O3 nanoparticles in 200 ml of toluene, add 2 g of isopropyl triisostearoyl titanate, react under nitrogen protection and magnetic stirring at 80 °C for 7 h, centrifuge, wash with toluene 3 times, and dry to obtain hydrophobized Al2O3 nanoparticles; (3) Redisperse 7 g of hydrophobized Al2O3 nanoparticles in 100 ml of toluene, add 3 g of heptadecafluorodecyltrimethoxysilane, stir and react at 50 - 60 °C for 4 h, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; (4) Mix 5 g of modified Al2O3 nanoparticles, 15 g of polymethylhydrosiloxane, 10 g of organopolysilazane, 10 g of divinylbenzene, 0.2 g of Kastredt catalyst and 70 - 80 ml of n-hexane, stir and mix evenly to obtain a modified liquid; (5) Immerse the wood in the hydrophobic silica sol and dry it at room temperature for 10 min, repeat twice, then spray the modification liquid by spraying, and the spraying amount is 120 g / m 2 , and cure it at room temperature.

[0016] Comparative Example 1: The difference from Example 2 is that triisostearoyl titanate is not used for modification. The specific steps are as follows: (1) Mix 24.8 ml of tetraethyl orthosilicate with 197.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 15.6 ml of ammonia water and 5 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, and gradually add 11 ml of methyltriethoxysilane dropwise, and continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Redisperse 6 g of Al2O3 nanoparticles in 100 ml of toluene, add 2.5 g of heptadecafluorodecyltrimethoxysilane, stir and react at 55 °C for 4 h, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; (3) Mix 4 g of modified Al2O3 nanoparticles, 13 g of polymethylhydrogensiloxane, 8 g of organopolysilazane, 5 - 108 g of divinylbenzene, 0.18 g of Kastredt catalyst and 75 ml of n-hexane, and stir and mix evenly to obtain a modification liquid; (4) Immerse the wood in the hydrophobic silica sol and dry it at room temperature for 10 min, repeat twice, then spray the modification liquid by spraying, and the spraying amount is 120 g / m 2 , and cure it at room temperature.

[0017] Comparative Example 2: The difference from Example 2 is that heptadecafluorodecyltrimethoxysilane is not used for modification. The specific steps are as follows: (1) Mix 24.8 ml of tetraethyl orthosilicate with 197.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 15.6 ml of ammonia water and 5 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, and gradually add 11 ml of methyltriethoxysilane dropwise, and continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Disperse 7 g of Al2O3 nanoparticles in 150 ml of toluene, add 1.8 g of triisostearoyl titanate, stir and react under nitrogen protection at 78 °C for 7 h, centrifuge, wash with toluene 3 times, and dry to obtain hydrophobized Al2O3 nanoparticles; (3) Mix the hydrophobized Al2O3 nanoparticles, 13 g of polymethylhydrogensiloxane, 8 g of organopolysilazane, 5 - 108 g of divinylbenzene, 0.18 g of Kastredt catalyst and 75 ml of n-hexane, and stir and mix evenly to obtain a modification liquid; (4) Immerse the wood in the hydrophobic silica sol and dry it at room temperature for 10 min, repeat twice, and then spray the modification liquid by spraying, with a spraying amount of 120 g / m 2 , and cure it at room temperature.

[0018] Comparative Example 3: The difference from Example 2 is that the alumina nanoparticles are not modified. The specific steps are as follows: (1) Mix 24.8 ml of tetraethyl orthosilicate with 197.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 15.6 ml of ammonia water and 5 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, gradually add 11 ml of methyltriethoxysilane dropwise, and continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Mix 4 g of Al2O3 nanoparticles, 13 g of polymethylhydrosiloxane, 8 g of organopolysilazane, 5 - 108 g of divinylbenzene, 0.18 g of Kastredt catalyst and 75 ml of n-hexane, and stir and mix evenly to obtain a modification liquid; (3) Immerse the wood in the hydrophobic silica sol and dry it at room temperature for 10 min, repeat twice, and then spray the modification liquid by spraying, with a spraying amount of 120 g / m 2 , and cure it at room temperature.

[0019] Comparative Example 4: (1) Mix 24.8 ml of tetraethyl orthosilicate with 197.2 ml of absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixture of 15.6 ml of ammonia water and 5 ml of deionized water, maintain reflux stirring at 60 °C for 3 h, gradually add 11 ml of methyltriethoxysilane dropwise, and continue stirring for 2 h to obtain a hydrophobic nano-silica sol; (2) Disperse 7 g of Al2O3 nanoparticles in 150 ml of toluene, add 1.8 g of isopropyl triisostearoyl titanate and 2.5 g of heptadecafluorodecyltrimethoxysilane, react under nitrogen protection and magnetic stirring at 78 °C for 7 h, centrifuge, wash with toluene 3 times, and dry to obtain modified Al2O3 nanoparticles; (3) Mix 4 g of modified Al2O3 nanoparticles, 13 g of polymethylhydrosiloxane, 8 g of organopolysilazane, 5 - 108 g of divinylbenzene, 0.18 g of Kastredt catalyst and 75 ml of n-hexane, and stir and mix evenly to obtain a modification liquid; (4) Immerse the wood in the hydrophobic silica sol and dry it at room temperature for 10 min, repeat twice, and then spray the modification liquid by spraying, with a spraying amount of 120 g / m 2 , and cure it at room temperature.

[0020] Performance Test Flexural strength: The flexural strength of the wood was determined with reference to GB / T 1936.1-2009 "Test Method for Flexural Strength of Wood". The test results are shown in Table 1; Impact toughness: The obtained samples were tested according to ASTM D143 standard. The test results are shown in Table 1; Water absorption rate: The obtained samples were tested according to GB / T 1934.1-2009. The test results are shown in Table 1; Alkali resistance: The wood obtained from the examples and comparative examples was completely immersed in the test solution, and the test solution was 5% NaOH solution (pH≈13). The obtained samples (50 mm×50 mm×5 mm) were completely immersed in the NaOH solution at 25°C. After 72 h, they were taken out, cleaned, dried and weighed, and the mass loss rate was recorded.

[0021] Weather resistance: The samples obtained from the examples and comparative examples were exposed to ultraviolet light (36W) with a wavelength of 356 nm. The height difference between the sample wood and the ultraviolet light was 20 cm. After irradiation for 120 h, they were taken out and the water contact angle on their surfaces was measured. Three samples were tested, and the average value was taken after arbitrarily selecting three points for each sample; the test results are shown in Table 1.

[0022]

[0023] Data analysis: From the data of the examples in Table 1, it can be seen that the organosilicon-modified superhydrophobic wood of the present invention has excellent mechanical properties, excellent hydrophobic properties, and excellent alkali resistance and weather resistance.

[0024] From Example 2 and Comparative Example 3 in the table, it can be seen that by adding nano-aluminum oxide ions in the present invention, on the one hand, it has certain alkali resistance and weather resistance itself, which can significantly improve the alkali resistance and weather resistance of the modified wood. On the other hand, it exists in the internal network of the surface coating, avoiding the risk of agglomeration, and its uniform distribution in the coating can further improve the mechanical properties and hydrophobic properties of the modified wood.

[0025] From Example 2 and Comparative Examples 1, 2, and 4 in the table, it can be seen that the present invention grafts and modifies the surface of alumina nanoparticles in a gradient manner, which can not only form a denser hydrophobic barrier to further reduce the water penetration under capillary action, and the gradient structure can further hinder the water penetration; on the other hand, the gradient design provides a double-layer alkali-resistant protective layer. The first layer provides basic alkali resistance, and the second layer further blocks the penetration of the alkali solution through the chemical inertness of the C-F bond. The multi-layer structure prolongs the diffusion path of the alkaline medium and slows down the corrosion rate; moreover, the gradient design can also further improve the influence of the modified wood on the external environment.

[0026] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A preparation method of organosilicon-modified superhydrophobic wood, characterized in that, It includes the following steps: (1) Configure hydrophobic silica sol; (2) Configure organosilicon modification liquid; (3) Dry the wood at 100 °C for 5 h, then immerse the wood in the hydrophobic silica sol, dry at room temperature for 10 min, repeat 2 - 3 times, then spray the organosilicon modification liquid on the wood surface and cure at room temperature to obtain organosilicon-modified superhydrophobic wood; The preparation steps of the organosilicon modification liquid described in step (2) are as follows: S1: Disperse Al2O3 nanoparticles in toluene, add triisooctanoyl titanate isopropyl ester, and carry out magnetic stirring reaction for 6 - 7 h under nitrogen protection at 75 - 80 °C, centrifuge, wash 3 times with toluene, and dry to obtain hydrophobized Al2O3 nanoparticles; S2: Redisperse the hydrophobized Al2O3 nanoparticles in toluene, add 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltrimethoxysilane, and carry out stirring reaction for 4 h at 50 - 60 °C, centrifuge and wash, and dry in vacuum at 60 °C to obtain modified Al2O3 nanoparticles; S3: Stir and mix the modified Al2O3 nanoparticles, polymethylhydrosiloxane, organopolysilazane, divinylbenzene, Kastredt catalyst, and n - hexane evenly to obtain the modification liquid; The dosage ratio of the Al2O3 nanoparticles, toluene, and triisooctanoyl titanate isopropyl ester described in step S1 is 5 - 8 g: 100 - 200 ml: 1.5 - 2 g; The dosage ratio of the hydrophobized Al2O3 nanoparticles, toluene, and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,7 - heptadecafluorodecyltrimethoxysilane described in step S2 is 5 - 7 g: 100 - 200 ml: 2 - 3 g; The dosage ratio of the modified Al2O3 nanoparticles, polymethylhydrosiloxane, organopolysilazane, divinylbenzene, Kastredt catalyst, and n - hexane described in step S3 is 3 - 5 g: 10 - 15 g: 5 - 10 g: 5 - 10 g: 0.15 - 0.2 g: 70 - 80 ml.

2. The preparation method of the silicone-modified superhydrophobic wood according to claim 1, wherein The preparation steps of the hydrophobic silica sol described in step (1) are as follows: Mix tetraethyl orthosilicate and absolute ethanol, stir at 60 °C for 10 min, then dropwise add a mixed solution of ammonia water and deionized water, maintain reflux stirring at 60 °C for 2 - 3 h, and gradually add methyltriethoxysilane, and continue stirring for 1 - 2 h to obtain hydrophobic nano - silica sol.

3. The preparation method of the silicone-modified superhydrophobic wood according to claim 2, characterized in that, The dosage ratio of the tetraethyl orthosilicate, absolute ethanol, ammonia water, deionized water, and methyltriethoxysilane is 12.4 - 37.2 ml: 97.2 - 291.6 ml: 7.8 - 23.37 ml: 1 - 10 ml: 5.5 - 16.6 ml.

4. The preparation method of the silicone-modified superhydrophobic wood according to claim 1, characterized in that, The spraying amount of the silicone-modified liquid described in step (3) is 80-120 g / m 2 .

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