A durable photocatalytic self-cleaning fluorine-free waterproof material, its preparation method and application

Abstract

This invention discloses a durable photocatalytic self-cleaning fluorine-free waterproof material, its preparation method, and its application, relating to the field of waterproof material technology. The durable photocatalytic self-cleaning fluorine-free waterproof material comprises, by weight, 0.2–3 parts of cationic titanium dioxide nanoparticles and 30–90 parts of modified polyurethane emulsion. This invention utilizes photocatalytically active TiO2 nanoparticles loaded onto the fiber surface and employs a heat treatment method to migrate low surface energy materials from the inner layer to the outermost layer. By leveraging the inherent physical properties of titanium dioxide, the hydrophobic properties of the fabric surface are repaired, further enhancing the durability of the fabric's hydrophobicity and giving the waterproof material a long-lasting and excellent waterproof effect.

Description

Technical Field

[0001] This invention relates to the field of waterproof materials technology, specifically to a durable photocatalytic self-cleaning fluorine-free waterproof material, its preparation method, and its application. Background Technology

[0002] Organic-inorganic nanohybrids are novel composite material systems combining organic and inorganic components at the nanoscale. Through the synergistic effect of each component at the micro- and nano-scale, they exhibit unique properties different from those of a single component. Inspired by the micro- and nano-scale rough structures of lotus leaves, scientists have constructed organic components with low surface energy and micro- and nano-scale inorganic rough structures on fabric surfaces, enabling water droplets to have a contact angle exceeding 150° and roll off easily. These fabric surfaces resist water-based stains and possess self-cleaning capabilities, finding wide application in waterproofing finishing. However, once waterproof fabric surfaces are contaminated with oily stains, simply rolling water droplets are insufficient to remove the oil, and the adhesion of oil weakens the waterproofing performance. Loading photocatalytic nanoparticles onto the fiber surface enables the photodegradation of organic pollutants adhering to the fabric surface.

[0003] Currently, most methods for achieving self-cleaning on waterproof surfaces primarily rely on the surface's resistance to wetting by water-based droplets. However, they do not exhibit significant anti-fouling properties against common organic pollutants in daily life. By incorporating photocatalytic nanoparticles into the self-cleaning coating, organic pollutants can be degraded simply through light exposure. Based on whether the low surface energy material used contains fluorine, self-cleaning photocatalytic coatings can be broadly categorized into two types: fluorine-free self-cleaning photocatalytic waterproof fabrics and fluorine-containing self-cleaning photocatalytic waterproof fabrics.

[0004] Good waterproof performance can be achieved on fabric surfaces using fluorine-free, low surface energy materials. Compared to fluorinated coatings, these coatings are more environmentally friendly, but they are less resistant to chemical corrosion and have poorer waterproof durability. Furthermore, most coatings use organic solvents for preparation, while water-based coatings without organic solvents meet environmental requirements and represent an important future direction in this field.

[0005] Because fluorinated substances have low surface energy, and compared to non-fluorinated hydrophobic carbon chains, these compounds have a stable chemical structure that is more difficult to be destroyed by photocatalysts during photocatalysis, thus achieving more stable and durable hydrophobic properties. However, the inherent defect of fluorinated compounds being difficult to degrade greatly limits the application market of self-cleaning fabrics.

[0006] In addition, while photocatalysis decomposes organic pollutants, it also damages the low surface energy materials coated on the fiber surface, leading to a gradual decrease in waterproof performance and consequently poor abrasion and wash resistance of the self-cleaning coating. Therefore, this invention aims to address these problems by constructing a superhydrophobic and photocatalytic dual-functional self-cleaning coating on the fabric surface, enabling the coating to possess self-healing capabilities against photocatalytic damage and high abrasion and wash resistance stability, thereby achieving the preparation of long-lasting self-cleaning fabrics. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a durable photocatalytic self-cleaning fluorine-free waterproof material, its preparation method, and its application.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A durable photocatalytic self-cleaning fluorine-free waterproof material comprises, by weight, 0.2 to 3 parts of cationic titanium dioxide nanoparticles and 30 to 90 parts of modified polyurethane emulsion.

[0010] The cationic titanium dioxide nanoparticles, by mass parts, comprise 1-6 parts tetrabutyl titanate, 1-6 parts long-chain alkyltrimethoxysilane, 0.5-3 parts ammonia, 35-65 parts ethanol, 0.5-1.5 parts γ-(methacryloyloxy)propyltrimethoxysilane, 0.05-0.15 parts acetic acid, 0.005-0.01 parts initiator, and 70-130 parts water.

[0011] The long-chain alkyltrimethoxysilane is one of dodecyltrimethoxysilane, tetradecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

[0012] The modified polyurethane emulsion, by weight parts, comprises 6-18 parts of polytetrahydrofuran, 10-50 parts of hydroxyl-terminated polysiloxane, 12-19 parts of N-methyldiethanolamine, 0.005-0.1 parts of the organobismuth compound Coscat® 83AC83 catalyst, 12-38 parts of isophorone diisocyanate, 10-20 parts of glyceryl carbonate, 1-10 parts of aminopropyltrialkoxysilane, 6-14.2 parts of glacial acetic acid, and 50-160 parts of water.

[0013] The polytetrahydrofuran is one of PTMG600, PTMG800, PTMG1000, PTMG2000, PTMG2500, PTMG3000, PTMG3500 and PTMG4000, the aminopropyltrialkoxysilane is aminopropyltriethoxysilane, and the hydroxyl-terminated polysiloxane is one of PDMS1000, PDMS1500, PDMS2000, PDMS3000, PDMS3600 and PDMS4500.

[0014] The second aspect of the present invention provides a method for preparing a durable photocatalytic self-cleaning fluorine-free waterproof material, comprising the following steps: adding cationic titanium dioxide nanoparticles to a modified polyurethane emulsion and stirring at 25-45°C for 3-5 hours.

[0015] The preparation of cationic titanium dioxide nanoparticles includes the following steps:

[0016] S1: Tetrabutyl titanate, long-chain alkyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, ammonia and ethanol are mixed and stirred at 30-60℃ for 8-16 hours. Hydrophobically modified and double-bonded titanium dioxide nanoparticles are synthesized by centrifugation, precipitation and washing.

[0017] S2: The prepared titanium dioxide nanoparticles, acetic acid, initiator, dimethylaminoethyl methacrylate, and water are mixed and ultrasonically dispersed, and the mixture is kept at 60-85℃ for 3-5 hours to obtain cationic titanium dioxide nanoparticles.

[0018] The preparation of the modified polyurethane emulsion includes the following steps: polytetrahydrofuran, isophorone diisocyanate, N-methyldiethanolamine, and the organic bismuth compound Coscat® 83 AC83 catalyst are mixed and heated to 65-90℃ and stirred for 1-4 h; after the reaction is completed, glycerol carbonate is added and the reaction is carried out at 30-60℃ for 1-4 h; after the reaction is completed, aminopropyltrialkoxysilane is added and the reaction is carried out at 30-60℃ for 1-4 h; after the reaction system cools to room temperature, glacial acetic acid of equimolar amount to N-methyldiethanolamine is added for neutralization reaction to obtain polyurethane prepolymer; water is added to the prepolymer for mechanical emulsification to obtain the modified polyurethane emulsion.

[0019] The third aspect of this invention provides the application of a durable photocatalytic self-cleaning fluorine-free waterproof material in the waterproof finishing of fabrics such as pure cotton, polyester-cotton blends, and polyester fibers.

[0020] The beneficial effects of this invention are:

[0021] (1) Based on the bifunctional hydrolysis condensation reaction and free radical thermal polymerization grafting theory, the present invention uses dimethylaminoethyl methacrylate to graft titanium dioxide nanoparticles modified with γ-(methacryloyloxy)propyltrimethoxysilane double bonds and long carbon chain to achieve surface cationization, thereby realizing the stable dispersion of titanium dioxide nanoparticles in water and avoiding the problem of residual emulsifiers in traditional emulsion polymerization products, avoiding the generation of harmful waste liquid, and making PvAC products purer;

[0022] (2) This invention utilizes the hydrolytic condensation of siloxanes in modified polyurethane emulsion with hydroxyl groups in surface cationized modified titanium dioxide nanoparticles and the selective deblocking of isocyanate groups by ester organic compounds at different application temperatures, so that the exposed isocyanate groups react with the hydroxyl groups on the substrate surface, thereby achieving stable chemical bonds between the organic and inorganic components in the waterproofing agent and between the waterproofing agent and the fabric, thus giving the finished fabric good waterproof durability.

[0023] (3) In view of the inherent defects of existing waterproofing additives, which can only resist water-based stains after being used to finish the fabric surface, while oil stains are difficult to remove and oil stains will weaken the waterproof performance and thus affect the waterproof durability, this invention loads TiO2 nanoparticles with photocatalytic effect on the fiber surface and uses heat treatment to make the low surface energy material in the inner layer migrate to the outermost layer. The invention utilizes the physical properties of titanium dioxide to repair the hydrophobic properties of the fabric surface, promotes the further improvement of the hydrophobic durability of the fabric surface, and gives the waterproof material a long-lasting and excellent waterproof effect. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The ammonia water used in this embodiment is commercially available industrial ammonia water. Example

[0026] Preparation of cationized titanium dioxide nanoparticles:

[0027] S1: Weigh 4g tetrabutyl titanate, 2g long-chain alkyltrimethoxysilane, 1g γ-(methacryloyloxy)propyltrimethoxysilane, 2g ammonia (28% by mass), 50g water and 50g ethanol and add them to the reaction flask in sequence. After mixing, heat the mixture to 60℃ at 300rpm and keep it at this temperature for 8h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0028] S2: The prepared nanoparticles, 0.1g acetic acid, 0.01g AIBN (dispersant), 1g dimethylaminoethyl methacrylate, and 50g water were ultrasonically dispersed in a reaction flask and reacted at 80℃ for 3h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0029] Preparation of modified polyurethane emulsion:

[0030] S1: Add 6g of polytetrahydrofuran, 12g of isophorone diisocyanate, 20g of hydroxyl-terminated polysiloxane (PDMS1000), and 8g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and hold for 2 h. In this example, the polytetrahydrofuran used is PTMG600.

[0031] S2: Add 10g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 40℃, and react for 2 hours;

[0032] S3: Add 3g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 40℃, and react for 2h;

[0033] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 100g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0034] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0035] 0.8g of cationic titanium dioxide nanoparticles were added to 70g of modified polyurethane emulsion and reacted at 300 rpm and 40℃ for 4 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0036] Preparation of cationized titanium dioxide nanoparticles:

[0037] S1: Weigh 4g tetrabutyl titanate, 3g long-chain alkyltrimethoxysilane, 1g γ-(methacryloyloxy)propyltrimethoxysilane, 2g ammonia (28% by mass), 50g water and 50g ethanol and add them to the reaction flask in sequence. After mixing, heat the mixture to 60℃ at 300rpm and keep it at this temperature for 8h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0038] S2: The prepared nanoparticles, 0.1g acetic acid, 0.01g AIBN (dispersant), 1g dimethylaminoethyl methacrylate, and 60g water were ultrasonically dispersed in a reaction flask and reacted at 80℃ for 3h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0039] Preparation of modified polyurethane emulsion:

[0040] S1: Add 6g of polytetrahydrofuran, 12g of isophorone diisocyanate, 20g of hydroxyl-terminated polysiloxane (PDMS1500), and 8g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and keep reacting for 2 h. In this example, the polytetrahydrofuran used is PTMG800.

[0041] S2: Add 10g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 40℃, and react for 2 hours;

[0042] S3: Add 3g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 40℃, and react for 2h;

[0043] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 100g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0044] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0045] 0.5g of cationic titanium dioxide nanoparticles were added to 70g of modified polyurethane emulsion and reacted at 300 rpm and 40℃ for 4 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0046] Preparation of cationized titanium dioxide nanoparticles:

[0047] S1: Weigh 1g tetrabutyl titanate, 1g long-chain alkyltrimethoxysilane, 0.5g γ-(methacryloyloxy)propyltrimethoxysilane, 0.5g ammonia (28% by mass), 35g water and 35g ethanol and add them to the reaction flask in sequence. After mixing, heat to 60℃ at 300rpm and keep the reaction at this temperature for 8h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0048] S2: The prepared nanoparticles, 0.05g acetic acid, 0.05g AIBN (dispersant), 0.5g dimethylaminoethyl methacrylate, and 35g water were ultrasonically dispersed in a reaction flask and reacted at 80℃ for 3h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0049] Preparation of modified polyurethane emulsion:

[0050] S1: Add 10g of polytetrahydrofuran, 14g of isophorone diisocyanate, 10g of hydroxyl-terminated polysiloxane (PDM2000), and 10g of N-methyldiethanolamine to a reaction flask, add 0.005g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and hold for 2 h. In this example, the polytetrahydrofuran used is PTMG1000.

[0051] S2: Add 10g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 40℃, and react for 2 hours;

[0052] S3: Add 5g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 40℃, and react for 2h;

[0053] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 50g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0054] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0055] 2g of cationic titanium dioxide nanoparticles were added to 90g of modified polyurethane emulsion and reacted at 300 rpm and 40℃ for 4 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0056] Preparation of cationized titanium dioxide nanoparticles:

[0057] S1: Weigh 2g tetrabutyl titanate, 2g long-chain alkyltrimethoxysilane, 0.5g γ-(methacryloyloxy)propyltrimethoxysilane, 1g ammonia (28% by mass), 50g water and 50g ethanol and add them to the reaction flask in sequence. After mixing, heat to 60℃ at 300rpm and keep the reaction at this temperature for 8h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0058] S2: The prepared nanoparticles, 0.1g acetic acid, 0.005g AIBN (dispersant), 1g dimethylaminoethyl methacrylate, and 50g water were ultrasonically dispersed in a reaction flask and reacted at 80℃ for 3h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0059] Preparation of modified polyurethane emulsion:

[0060] S1: Add 8g of polytetrahydrofuran, 18g of isophorone diisocyanate, 20g of hydroxyl-terminated polysiloxane (PDMS3000), and 12g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and hold for 2 h. In this example, the polytetrahydrofuran used is PTMG2000.

[0061] S2: Add 15g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 40℃, and react for 2 hours;

[0062] S3: Add 8g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 40℃, and react for 2h;

[0063] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 80g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0064] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0065] 0.8g of cationic titanium dioxide nanoparticles were added to 50g of modified polyurethane emulsion and reacted at 300 rpm and 40℃ for 4 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0066] Preparation of cationized titanium dioxide nanoparticles:

[0067] S1: Weigh 3g tetrabutyl titanate, 4g long-chain alkyltrimethoxysilane, 1.5g γ-(methacryloyloxy)propyltrimethoxysilane, 2g ammonia (28% by mass), 60g water and 60g ethanol and add them to the reaction flask in sequence. After mixing, heat to 30℃ at 300rpm and keep the reaction at this temperature for 16h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0068] S2: The prepared nanoparticles, 0.15g acetic acid, 0.015g AIBN (dispersant), 1.5g dimethylaminoethyl methacrylate, and 60g water were ultrasonically dispersed in a reaction flask and reacted at 60℃ for 5h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0069] Preparation of modified polyurethane emulsion:

[0070] S1: Add 11g of polytetrahydrofuran, 20g of isophorone diisocyanate, 30g of hydroxyl-terminated polysiloxane (PDMS3600), and 12g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and hold for 2 h. In this example, the polytetrahydrofuran used is PTMG2500.

[0071] S2: Add 18g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 50℃, and react for 2 hours;

[0072] S3: Add 10g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 40℃, and react for 2h;

[0073] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 100g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0074] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0075] 3g of cationic titanium dioxide nanoparticles were added to 90g of modified polyurethane emulsion and reacted at 300 rpm and 40℃ for 4 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0076] Preparation of cationized titanium dioxide nanoparticles:

[0077] S1: Weigh 5g tetrabutyl titanate, 6g long-chain alkyltrimethoxysilane, 1.5g γ-(methacryloyloxy)propyltrimethoxysilane, 3g ammonia (28% by mass), 60g water and 60g ethanol and add them to the reaction flask in sequence. After mixing, heat to 50℃ at 200rpm and keep the reaction at this temperature for 10h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0078] S2: The prepared nanoparticles, 0.1g acetic acid, 0.01g AIBN (dispersant), 0.5g dimethylaminoethyl methacrylate, and 65g water were ultrasonically dispersed in a reaction flask and reacted at 85℃ for 4h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0079] Preparation of modified polyurethane emulsion:

[0080] S1: Add 10g of polytetrahydrofuran, 30g of isophorone diisocyanate, 40g of hydroxyl-terminated polysiloxane (PDMS4500), and 15g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 65°C at 50 rpm and keep reacting for 4 h. In this example, the polytetrahydrofuran used is PTMG4000.

[0081] S2: Add 20g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 30℃, and react for 4 hours;

[0082] S3: Add 1g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 60℃, and react for 1h;

[0083] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 150g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0084] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0085] 0.8g of cationic titanium dioxide nanoparticles were added to 70g of modified polyurethane emulsion and reacted at 200 rpm and 45℃ for 3 hours. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface. Example

[0086] Preparation of cationized titanium dioxide nanoparticles:

[0087] S1: Weigh 6g tetrabutyl titanate, 6g long-chain alkyltrimethoxysilane, 1.5g γ-(methacryloyloxy)propyltrimethoxysilane, 3g ammonia (28% by mass), 65g water and 65g ethanol and add them to the reaction flask in sequence. After mixing, heat to 30℃ at 400rpm and keep the reaction at this temperature for 8h. After centrifugation, precipitation and washing, hydrophobically modified and double-bond modified titanium dioxide nanoparticles are obtained.

[0088] S2: The prepared nanoparticles, 0.15g acetic acid, 0.01g AIBN (dispersant), 1.5g dimethylaminoethyl methacrylate, and 65g water were ultrasonically dispersed in a reaction flask and reacted at 60℃ for 5h. The cationic titanium dioxide nanoparticles were obtained by centrifugation and drying.

[0089] Preparation of modified polyurethane emulsion:

[0090] S1: Add 16g of polytetrahydrofuran, 38g of isophorone diisocyanate, 50g of hydroxyl-terminated polysiloxane (PDMS1000), and 19g of N-methyldiethanolamine to a reaction flask, add 0.01g of organic bismuth compound Coscat® 83 AC83 catalyst, heat to 85°C at 150 rpm and hold for 2 h. In this example, the polytetrahydrofuran used is PTMG1000.

[0091] S2: Add 20g of glyceryl carbonate to the reaction flask, maintain the reaction temperature at 60℃, and react for 1 hour;

[0092] S3: Add 3g of aminopropyltrialkoxysilane to the reaction flask, maintain the reaction temperature at 30℃, and react for 4h;

[0093] S4: After the reaction system temperature drops to room temperature, add glacial acetic acid in equimolar amounts with N-methyldiethanolamine to neutralize the reaction for 30 min, then add 160g of water for mechanical emulsification to obtain a polyurethane emulsion.

[0094] Durable photocatalytic self-cleaning fluorine-free waterproof material:

[0095] 0.2g of cationic titanium dioxide nanoparticles were added to 30g of modified polyurethane emulsion and reacted at 200 rpm and 25℃ for 3h. The durable photocatalytic self-cleaning fluorine-free waterproof material was obtained by hydrolysis and condensation of the siloxy groups in the modified polyurethane emulsion with the hydroxyl groups in the cationic modified titanium dioxide nanoparticles on the surface.

[0096] Comparative Example 1

[0097] Unlike Example 1, the titanium dioxide particles in the comparative example are not cationized. The specific preparation method of the titanium dioxide particles is as follows:

[0098] S1: According to the mass fraction, weigh 4g tetrabutyl titanate, 2g long-chain alkyltrimethoxysilane, 1g γ-(methacryloyloxy)propyltrimethoxysilane, 2g ammonia water (28% mass fraction), 50g water and 50g ethanol mixed solution and added to the deionized water in the reaction flask in sequence. After mixing, heat to 60℃ at 300rpm and keep the reaction at this temperature for 8h. After centrifugation, precipitation and washing, long carbon chain modified titanium dioxide nanoparticles are obtained.

[0099] Comparative Example 2

[0100] Unlike Example 1, glycerol carbonate was not added for modification when preparing the modified polyurethane emulsion.

[0101] Comparative Example 3

[0102] Unlike Example 1, aminopropyltrialkoxysilane was not added for modification when preparing the modified polyurethane emulsion.

[0103] Comparative Example 4

[0104] test:

[0105] The waterproof materials prepared in the examples and comparative examples were used to treat cotton fabrics with a water repellent agent at 80 g / L using a pad-bake finishing process. After impregnation, the fabrics were treated with a 70% pad-in solution and baked at 110°C for 2 minutes. Additionally, a group of waterproof materials prepared in Example 1 were used to treat cotton fabrics with a water repellent agent at 80 g / L using a pad-bake finishing process. After impregnation, the fabrics were treated with a 70% pad-in solution and baked at 150°C for 2 minutes as Comparative Example 4.

[0106] Fabric surface and waterproofing effect analysis:

[0107] Compared to Comparative Example 1, all embodiments showed more stable emulsion states and superior waterproof durability on the treated fabric surface. The emulsions prepared according to the formulations of each embodiment were applied to the fabric surface and washed 30 times. Similarly, the emulsion prepared using the formulation of Comparative Example 1 was applied to the fabric surface using the same method and washed 30 times. Different liquids (milk, water droplets, coffee, tea, and soy milk) were dripped onto the treated and washed fabric surface. The experiment showed that the liquids formed relatively regular spherical shapes on the fabric surface treated and washed with the formulations of each embodiment, exhibiting good... The water-repellent effect is evident when different liquids (milk, water droplets, coffee, tea, and soy milk) are dropped onto the surface of the treated fabric after washing in Comparative Example 1. The liquids exhibit irregular elliptical shapes because the titanium dioxide nanoparticles in the example undergo surface cationization, resulting in better water dispersibility. Furthermore, after being treated onto the fabric surface, stable chemical bonds are formed between the organic and inorganic components of the waterproofing agent, as well as between the waterproofing agent and the fabric. In contrast, in Comparative Example 1, the titanium dioxide nanoparticles have too few surface hydroxyl groups and only adhere to the fabric surface through physical means, thus exhibiting poor waterproof durability.

[0108] Compared with Comparative Example 2, all examples showed poorer water resistance and durability after being applied to the fabric surface. The emulsion prepared using the formulation of Comparative Example 2 was applied to the fabric surface using the same method and washed 30 times. Different liquids (milk, water droplets, coffee, tea, and soy milk) were dropped onto the surface of the treated and washed fabric and compared with each example. The experiment found that when different liquids (milk, water droplets, coffee, tea, and soy milk) were dropped onto the surface of the treated fabric after washing in Comparative Example 2, the liquids showed irregular elliptical shapes. The water resistance effect was significantly worse than the hydrophobic effect of the fabric surface treated and washed using the formulations of each example. This is because glyceryl carbonate was not added in Comparative Example 2, so the water-repellent agent did not form a chemical bond with the fabric surface, thus exhibiting poor water resistance and durability.

[0109] Similarly, using the same method, compared with Comparative Example 3, all examples showed that Comparative Example 3 exhibited poorer waterproofing after being washed 30 times on the fabric surface. That is, Comparative Example 3 showed poorer waterproofing durability because the absence of aminopropyltriethoxysilane in Comparative Example 3 resulted in a lack of chemical bond between the inorganic components and the organic components in the waterproofing agent, thus leading to poorer waterproofing durability.

[0110] Compared with Comparative Example 4, Example 1 showed similar photocatalytic self-cleaning effect and waterproof durability after being treated on the fabric surface, even at different treatment temperatures. This is because even at lower setting temperatures, glyceryl carbonate can form stable chemical bonds with the fabric surface, exhibiting excellent waterproof durability.

[0111] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing a durable photocatalytic self-cleaning fluorine-free waterproof material, characterized in that, Includes the following steps: Cationic titanium dioxide nanoparticles were added to the modified polyurethane emulsion and reacted at 25-45℃ with stirring for 3-5 hours. The preparation of the cationic titanium dioxide nanoparticles includes the following steps: S1: Tetrabutyl titanate, long-chain alkyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, ammonia and ethanol are mixed and stirred at 30-60℃ for 8-16 hours. Hydrophobically modified and double-bonded titanium dioxide nanoparticles are synthesized by centrifugation, precipitation and washing. S2: The prepared titanium dioxide nanoparticles, acetic acid, initiator, dimethylaminoethyl methacrylate and water are mixed and ultrasonically dispersed, and the mixture is kept at 60-85℃ for 3-5 hours to obtain cationic titanium dioxide nanoparticles. The preparation of the modified polyurethane emulsion includes the following steps: Polytetrahydrofuran, isophorone diisocyanate, hydroxyl-terminated polysiloxane, N-methyldiethanolamine, and the organobismuth compound Coscat® 83 AC83 catalyst were mixed and heated to 65–90 °C and stirred for 1–4 h. After the reaction was completed, glycerol carbonate was added and the mixture was kept at 30–60 °C for 1–4 h. After the reaction was completed, aminopropyltrialkoxysilane was added and the mixture was kept at 30–60 °C for 1–4 h. After the reaction system cooled to room temperature, glacial acetic acid of equimolar amount to N-methyldiethanolamine was added for neutralization to obtain a polyurethane prepolymer. Water was added to the prepolymer for mechanical emulsification to obtain a modified polyurethane emulsion.

2. The method for preparing the fluorine-free waterproof material according to claim 1, characterized in that: The cationic titanium dioxide nanoparticles, by mass parts, comprise 1-6 parts tetrabutyl titanate, 1-6 parts long-chain alkyltrimethoxysilane, 0.5-3 parts ammonia, 35-65 parts ethanol, 0.5-1.5 parts γ-(methacryloyloxy)propyltrimethoxysilane, 0.05-0.15 parts acetic acid, 0.005-0.01 parts initiator, and 70-130 parts water.

3. The method for preparing the fluorine-free waterproof material according to claim 2, characterized in that: The long-chain alkyltrimethoxysilane is one of dodecyltrimethoxysilane, tetradecyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane.

4. The method for preparing the fluorine-free waterproof material according to claim 1, characterized in that: The modified polyurethane emulsion, by weight parts, comprises 6-18 parts of polytetrahydrofuran, 10-50 parts of hydroxyl-terminated polysiloxane, 12-19 parts of N-methyldiethanolamine, 0.005-0.1 parts of the organobismubyl compound Coscat® 83 AC83 catalyst, 12-38 parts of isophorone diisocyanate, 10-20 parts of glyceryl carbonate, 1-10 parts of aminopropyltrialkoxysilane, 6-14.2 parts of glacial acetic acid, and 50-160 parts of water.

5. The method for preparing the fluorine-free waterproof material according to claim 4, characterized in that: The polytetrahydrofuran is one of PTMG600, PTMG800, PTMG1000, PTMG2000, PTMG2500, PTMG3000, PTMG3500 and PTMG4000, the aminopropyltrialkoxysilane is aminopropyltriethoxysilane, and the hydroxyl-terminated polysiloxane is one of PDMS1000, PDMS1500, PDMS2000, PDMS3000, PDMS3600 and PDMS4500.

6. The durable photocatalytic self-cleaning fluorine-free waterproof material prepared by the preparation method according to any one of claims 1 to 5, characterized in that: It comprises 0.2 to 3 parts by weight of cationic titanium dioxide nanoparticles and 30 to 90 parts by weight of modified polyurethane emulsion.

7. The application of the durable photocatalytic self-cleaning fluorine-free waterproof material according to claim 6 in the waterproof finishing of pure cotton, polyester-cotton blends, and polyester fabrics.