A method for preparing a post-wash naturally air-drying hydrophobicity self-restoration water-repellent textile

Abstract

The application discloses a preparation method of a self-recovery water-repellent textile capable of being naturally dried after washing, and belongs to the field of textile printing and dyeing auxiliaries and textile dyeing and finishing processing. The method comprises the following steps: obtaining a nano-titanium dioxide gel by using a titanium source, an organic solvent, a reaction catalyst and deionized water, and then step by step finishing a fabric by using an ethanol solution of the nano-titanium dioxide gel and a water solution of a water-repellent agent. The application utilizes the ability of nano-titanium dioxide to absorb ultraviolet rays in sunlight and convert light energy into heat energy, so that the obtained fabric not only has excellent water-repellent effect (high static water contact angle, high static water pressure resistance and high spray resistance grade), but also has the ability of effectively recovering the spray resistance grade after being naturally dried without drying after washing. The application solves the problem that the water-repellent performance of a conventional water-repellent finished fabric is reduced after being naturally dried after washing in a service process, and the water-repellent performance is recovered by high-temperature drying (greater than or equal to 55 DEG C).

Description

Technical Field

[0001] The invention relates to a method for preparing a water-repellent textile with self-recovering hydrophobicity after washing and naturally drying, and belongs to the field of textile printing and dyeing auxiliaries and textile dyeing and finishing. Background Art

[0002] With the development of science and technology and the continuous improvement of people's living standards, water-repellent textiles have gradually come into the public eye and are being widely used. Although fabrics treated with conventional water-repellent agents have good water-repellency, the water-repellency deteriorates after washing and air-drying, while it recovers after high-temperature drying (≥55°C). This has led to a decline in consumer satisfaction with water-repellent textiles in countries where air-drying is the primary drying method. Summary of the Invention

[0003] To address these issues, and to improve the water-repellent effect of water-repellent-finished fabrics after washing and air-drying, while avoiding the energy consumption of high-temperature drying, the present invention has developed a method for preparing water-repellent textiles that self-recover their hydrophobic properties after washing and air-drying. This method uses nano-titanium dioxide gel in combination with a water-repellent to finish the fabric. The resulting fabric not only exhibits excellent water-repellent properties but also recovers its water-repellent properties after washing, eliminating the need for high-temperature drying. Air-drying allows the fabric to recover its water-repellent properties.

[0004] The object of the present invention is to provide a method for preparing a water-repellent textile with self-recovering hydrophobic properties after washing and drying naturally, the method comprising:

[0005] (1) adding a mixture B of an organic solvent, a reaction catalyst, and deionized water dropwise to a mixture A of a titanium source and an organic solvent, and reacting under stirring to obtain a nano-titanium dioxide solution;

[0006] (2) removing the organic solvent from the nano-titanium dioxide solution obtained in step (1) by rotary evaporation and aging at room temperature to obtain a nano-titanium dioxide gel;

[0007] (3) dipping the fabric into the ethanol solution of the nano-titanium dioxide gel obtained in step (2) and then drying;

[0008] (4) The fabric obtained in step (3) is immersed in an aqueous solution of a water repellent and then finished by a padding and baking process.

[0009] In one embodiment of the present invention, the mass ratio of mixed solution A to mixed solution B in step (1) is 0.8 to 1.5:1.

[0010] In one embodiment of the present invention, the components in the mixed solution A in step (1) include, by mass percentage, 5-20% of titanium source and 80-95% of organic solvent; the components in the mixed solution B include, by mass percentage, 80-90% of organic solvent and 1-10% of reaction catalyst, with the remainder being deionized water.

[0011] In one embodiment of the present application, the titanium source in step (1) is at least one of ethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride or titanium trichloride; the organic solvent is at least one of ethanol, propanol or isopropanol; and the reaction catalyst is at least one of glacial acetic acid, nitric acid or hydrochloric acid.

[0012] In one embodiment of the present application, the adding speed of the mixed solution B in step (1) is 1-10 g / min, and the stirring speed is 100-1000 r / min; and the reaction time is 1-8 h.

[0013] In one embodiment of the present application, the aging time in step (2) is 12-48 h.

[0014] In one embodiment of the present application, the concentration of nano-titanium dioxide in the ethanol solution of nano-titanium dioxide gel in step (3) is 0.5-10 g / L; and the pick-up rate in the padding process is 80-150%, the drying temperature is 80-100℃, and the drying time is 1-5 min.

[0015] In one embodiment of the present application, the water repellent agent in step (4) includes at least one of acrylate-based fluorine-free water repellent agent, silicone-based fluorine-free water repellent agent, polyurethane-based fluorine-free water repellent agent or fluorine-containing water repellent agent.

[0016] In one embodiment of the present application, the concentration of the water repellent agent in step (4) is 50-100 g / L, and the pick-up rate in the pad-dry-cure process is 50-150%.

[0017] In one embodiment of the present application, in step (4), when finishing the fabric by using the pad-dry-cure process, the fabric is padded in the water solution of the water repellent agent, and then the fabric is pre-dried and cured, the pre-drying temperature is 80-110℃, the pre-drying time is 1-5 min, the curing temperature is 130-160℃, and the curing time is 1-5 min.

[0018] In one embodiment of the present application, the fabric includes one of cotton, wool, hemp, polyester and nylon fabric.

[0019] The present application has the following beneficial effects:

[0020] 1. The present application finishes the fabric by combining nano-titanium dioxide gel and water repellent agent, and prepares a kind of self-recovery water-repellent textile with natural air-drying and hydrophobic performance after washing.

[0021] 2. The self-recovering hydrophobic fabric prepared by the present invention can absorb ultraviolet rays from sunlight during natural airing after washing, restoring its water repellency to pre-wash levels. This solves the problem of conventional water-repellent treated fabrics losing water repellency after washing and requiring drying at high temperatures (≥55°C) to restore it, a cumbersome and energy-intensive process. This self-recovering hydrophobic fabric can reduce the temperature required to restore its water repellency after washing, saving energy and reducing costs.

[0022] 3. The present invention uses nano-titanium dioxide ethanol solution to finish the fabric before water-repellent finishing, thereby improving the surface roughness of the water-repellent fabric, and the fabric can obtain a better water-repellent effect after finishing.

[0023] 4. The combined treatment method of nano-titanium dioxide and a water repellent provided by the present invention is simple to operate, produces a uniform product, and forms a water-repellent film on the fabric surface, significantly enhancing the fabric's water repellency. Overall, the treated fabric exhibits excellent water repellency, breathability, and self-recovery of its hydrophobic properties. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to specific examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention.

[0025] Common commercially available water repellents are divided into two categories: fluorine-free (acrylates, silicones, and polyurethanes) and fluorine-containing. The water repellents used in the examples and comparative examples of the present invention are acrylate fluorine-free water repellent (fluorine-free 1), silicone fluorine-free water repellent (fluorine-free 2), polyurethane fluorine-free water repellent (fluorine-free 3), and fluorine-containing water repellent 1 (fluorine 1). The preparation methods are as follows:

[0026] Preparation of fluorine-free acrylic water repellent 1 (fluorine-free 1):

[0027] A mixture of acrylate monomers (octadecyl acrylate, tetrabutyl acrylate, methyl methacrylate, and glycidyl methacrylate in a molar ratio of 1:1:1:0.4) was added to a deionized aqueous solution of octadecyltrimethylammonium chloride and polyoxyethylene stearate (polyoxyethylene number is 20) accounting for 10% of the total mass of the reaction monomers for emulsification (wherein the mass ratio of octadecyltrimethylammonium chloride to polyoxyethylene stearate is 1:2.5, and the total mass of the reaction monomers accounts for 20% of the mass of the emulsion). After the emulsion was heated to 80°C, an aqueous solution of azobisisobutylamidine accounting for 1% of the total mass of the reaction monomers (the mass ratio of azobisisobutylamidine to water was 1:20) was added dropwise. After the addition was completed, the reaction was kept warm for 3 hours and naturally cooled to room temperature to obtain an acrylate fluorine-free water repellent (fluorine-free 1).

[0028] Preparation of silicone fluorine-free water repellent 2 (fluorine-free 2):

[0029] Methylpropionyl chloride was added to an acetone solution of aminopropyl diblocked polydimethylsiloxane (molecular weight 1000) in three batches (with an interval of 0.5 h) (the molar ratio of methylpropionyl chloride to aminopropyl diblocked polydimethylsiloxane was 1:1, and the mass ratio of aminopropyl diblocked polydimethylsiloxane to acetone was 1:2), and the mixture was reacted at room temperature for 4 h. A deionized water solution of octadecyltrimethylammonium chloride and polyoxyethylene stearate (polyoxyethylene number was 20) accounting for 10% of the total mass of the reaction monomers was added for emulsification (the mass ratio of octadecyltrimethylammonium chloride to polyoxyethylene stearate was 1:2, and the total mass of the reaction monomers accounted for 20% of the mass of the emulsion). After high-speed mechanical stirring to obtain an emulsion, the acetone was removed by rotary evaporation to obtain a silicone-based fluorine-free water repellent (fluorine-free 2).

[0030] Preparation of polyurethane fluorine-free water repellent 3 (fluorine-free 3):

[0031] Isophorone diisocyanate was added dropwise to polytetrahydrofuran (isophorone diisocyanate to polytetrahydrofuran molar ratio of 3.2:1). The mixture was stirred and reacted at 85°C in an anhydrous environment for 2 hours. The mixture was cooled to 45°C and N-methyldiethanolamine dissolved in acetone (isophorone diisocyanate to N-methyldiethanolamine molar ratio of 4:1) was added. The reaction was continued for 1.5 hours. The temperature was raised to 65°C and trimethylolpropane monoallyl ether (isophorone diisocyanate to trimethylolpropane monoallyl ether molar ratio of 4:1) was added. The reaction was continued for 2 hours. Methyl ethyl ketone oxime (isophorone diisocyanate to methyl ethyl ketone oxime molar ratio of 3:1) was added to the reactor and the mixture was reacted at 70°C for 3 hours to cap the reaction. After the end-capping, the polyurethane obtained was added with acrylate monomer (methyl methacrylate: butyl acrylate: octadecyl acrylate molar ratio = 1:1:1, the total mass of the acrylate monomer to the total mass of the polyurethane monomer was 1:1), the reaction mixture was cooled to 35 ° C, and acetic acid (neutralization degree was 100%) was added as a neutralizer and reacted for 0.5 hours. Deionized water (the total mass of the acrylate monomer and the polyurethane monomer was 4 times that of the deionized water) was slowly added under vigorous stirring (1200r / min), the temperature was raised to 75 ° C, and an aqueous solution of azobisisobutylamidine (the mass ratio of azobisisobutylamidine to water was 1:20) accounting for 1% of the total weight of the acrylate monomer was added dropwise to the reactor. The reaction was kept warm for 3 hours to obtain a polyurethane fluorine-free water repellent (fluorine-free 3).

[0032] Preparation of fluorine-containing water repellent 1 (fluorine 1):

[0033] A mixture of 1H,1H,2H,2H-perfluorohexanol acrylate: octadecyl acrylate: methyl methacrylate: glycidyl methacrylate (molar ratio of 2:1:1:0.4) was added to a deionized aqueous solution of octadecyltrimethylammonium chloride and polyoxyethylene stearate (polyoxyethylene number is 20) accounting for 10% of the total mass of the reaction monomers for emulsification (wherein the mass ratio of octadecyltrimethylammonium chloride to polyoxyethylene stearate is 1:3, and the total mass of the reaction monomers accounts for 20% of the mass of the emulsion). After the emulsion was heated to 80°C, an aqueous solution of azobisisobutylamidine (mass ratio of azobisisobutylamidine to water is 1:20) accounting for 1% of the total mass of the reaction monomers was added dropwise. After the addition was completed, the reaction was kept warm for 3 hours and naturally cooled to room temperature to obtain a fluorine-containing water repellent 1 (fluorine 1).

[0034] Test method:

[0035] The spray resistance of the fabric's water repellency is assessed by the water level, and the water level of the fabric after drying is tested according to GB / T 4745-2012 Testing and evaluation of water repellency of textiles - Water level test method.

[0036] The water repellency and water wetting resistance of the fabric are evaluated by the static water contact angle. The static contact angle of the fabric after water repellent finishing is measured using a contact angle meter: 5 μL of water droplets are added to five different positions of the fabric and the static contact angles are measured.

[0037] The static water resistance of the fabric water repellency is carried out according to the AATCC-127-2013 "Water Resistance: Hydrostatic Pressure Test" standard.

[0038] Fabric washing and drying parameters: The fabric was washed according to GB / T8629-2017 "Household Washing and Drying Procedure for Textile Experiments". After washing, the fabric was exposed to sunlight at 30°C for 1 hour in a sunlight fastness meter.

[0039] The evaluation of fabric softness was carried out in accordance with AATCC TM 202 “Evaluation of Relative Handle of Textiles and Garments: Instrumental Method”.

[0040] Example 1:

[0041] The following steps were followed to prepare nano-titanium dioxide gel and to combine it with a water repellent to finish the fabric:

[0042] Preparation of nano-titanium dioxide gel:

[0043] At room temperature, tetrabutyl titanate was slowly added to a mixture of ethanol and glacial acetic acid (the mass ratio of tetrabutyl titanate, ethanol, and glacial acetic acid was 10:80:10) to obtain mixed solution A. Ethanol, glacial acetic acid, and deionized water were mixed in a mass ratio of 80:10:10 to obtain mixed solution B. The mass ratio of mixed solution A to mixed solution B was 1:1. Solution B was added to solution A at a rate of 2 g / min while stirring at a speed of 600 r / min. After the addition was completed, the reaction was allowed to proceed for 4 hours. The ethanol was removed by rotary evaporation and the mixture was allowed to stand for 24 hours to obtain a titanium dioxide gel.

[0044] Fabric Finishing:

[0045] A certain amount of nano-titanium dioxide gel was diluted in ethanol to prepare a 1g / L titanium dioxide ethanol solution. Cotton fabric was impregnated with this solution and then rolled to a 100% roll-off ratio. The fabric was then dried at 100°C for 2 minutes. The fabric was then immersed in a 60g / L aqueous solution of acrylate-based fluorine-free water repellent 1 (Fluorine-free 1) for finishing. A roll-and-bake process was used: a double dip and double roll-up process with a 100% roll-off ratio. The fabric was pre-dried at 100°C for 2 minutes and then baked at 150°C for 3 minutes. The relevant parameters of the treated fabric are shown in Table 1.

[0046] Example 2-4:

[0047] Preparation of nano-titanium dioxide gel: same as in Example 1.

[0048] Fabric finishing: Only the concentration of the nano-titanium dioxide treatment solution was changed (0.5 g / L in Example 2, 5 g / L in Example 3, and 10 g / L in Example 4), and the rest was the same as in Example 1. The relevant parameters of the treated fabrics are shown in Table 1.

[0049] Example 5-7:

[0050] Preparation of nano-titanium dioxide gel: same as in Example 1.

[0051] Fabric finishing: Only the type of water repellent was changed (Example 5 was silicone-based fluorine-free water repellent 2 (Fluorine-free 2), Example 6 was polyurethane-based fluorine-free water repellent 3 (Fluorine-free 3), and Example 7 was fluorine-containing water repellent 1 (Fluorine 1). Other parameters were the same as in Example 1. The relevant parameters of the treated fabrics are shown in Table 2.

[0052] Example 8-9:

[0053] Preparation of nano-titanium dioxide gel: same as in Example 1.

[0054] Fabric finishing: Only the type of fabric was changed (polyester in Example 8 and nylon in Example 9), and the rest was the same as in Example 1. The relevant parameters of the treated fabrics are shown in Table 1.

[0055] Example 10:

[0056] Follow the steps below to prepare nano-titanium dioxide solution and combine it with water repellent to finish the fabric:

[0057] Preparation of nano-titanium dioxide gel:

[0058] At room temperature, ethyl titanate was slowly added to a mixture of propanol and nitric acid (1 g / L) (the mass ratio of ethyl titanate, propanol, and nitric acid was 20:75:5) to obtain mixed solution A. Propanol, nitric acid (1 g / L), and deionized water were mixed in a mass ratio of 80:5:15 to obtain mixed solution B. The mass ratio of mixed solution A to mixed solution B was 0.8:1. Solution B was added to solution A at a rate of 1 g / min while stirring at 100 r / min. After the addition was complete, the reaction was allowed to react for 1 hour. Ethanol was removed by rotary evaporation and the mixture was allowed to stand for 48 hours to obtain a titanium dioxide gel.

[0059] Fabric Finishing:

[0060] A certain amount of nano-titanium dioxide gel was diluted in ethanol to prepare a 1g / L titanium dioxide ethanol solution. Cotton fabric was impregnated with this solution and then rolled to a roll-off ratio of 80%. The fabric was then baked at 80°C for 5 minutes. The fabric was then immersed in a 50g / L aqueous solution of an acrylic fluorine-free water repellent 1 (Fluorine-free 1) for finishing. A roll-baking process was used: two dips and two rolls, with a roll-off ratio of 150%. The fabric was pre-baked at 80°C for 5 minutes and baked at 160°C for 1 minute. The relevant parameters of the treated fabric are shown in Table 1.

[0061] Example 11:

[0062] Follow the steps below to prepare nano-titanium dioxide solution and combine it with water repellent to finish the fabric:

[0063] Preparation of nano-titanium dioxide gel:

[0064] At room temperature, tetraisopropyl titanate was slowly added to a mixture of isopropyl alcohol and hydrochloric acid (0.5 g / L) (the mass ratio of ethyl titanate, isopropyl alcohol, and hydrochloric acid was 20:60:20) to obtain mixed solution A. Mixed solution B was obtained by mixing isopropyl alcohol, hydrochloric acid (0.5 g / L), and deionized water in a mass ratio of 70:10:20. The mass ratio of mixed solution A to mixed solution B was 1.5:1. Solution B was added to solution A at a rate of 1 g / min while stirring at 1000 r / min. After the addition was complete, the reaction was allowed to proceed for 8 hours. Ethanol was removed by rotary evaporation and the mixture was allowed to stand for 12 hours to obtain a titanium dioxide gel.

[0065] Fabric Finishing:

[0066] A certain amount of nano-titanium dioxide gel was diluted in ethanol to prepare a 1 g / L titanium dioxide ethanol solution. The cotton fabric was immersed in the above solution and then pressed, with a pick-up of 150%, and dried at 90°C for 3 min. The fabric was then immersed in an aqueous solution (100 g / L) of fluorine-free water repellent 1 (fluorine-free 1) and treated by pad-dry-cure, with two immersions and two pressings, a pick-up of 50%, pre-drying at 90°C for 3 min, and curing at 130°C for 5 min. The relevant parameters of the treated fabric are shown in Table 1.

[0067] Comparative Example 1-2:

[0068] Preparation of nano-titanium dioxide gel: same as in Example 1.

[0069] Fabric finishing: only the concentration of the nano-titanium dioxide treatment solution was changed (0.1 g / L in Comparative Example 1 and 20 g / L in Comparative Example 2), and the other conditions were the same as in Example 1. The relevant parameters of the treated fabric are shown in Table 1.

[0070] Comparative Example 3:

[0071] The nano-titanium dioxide solution was prepared according to the following steps and used in combination with a water repellent to finish the fabric:

[0072] Preparation of nano-titanium dioxide gel:

[0073] At room temperature, tetrabutyl titanate was slowly added to a mixture of ethanol and glacial acetic acid (the mass ratio of tetrabutyl titanate, ethanol and glacial acetic acid was 1:90:9) to obtain mixture A; ethanol, glacial acetic acid and deionized water were mixed in a mass ratio of 40:3:57 to obtain mixture B; A:B=(2:1, mass ratio); B was added to A at a rate of 2 g / min while stirring at a speed of 600 r / min, and after the addition was completed, the reaction was continued for 4 h. After removing ethanol by rotary evaporation, the mixture was left to stand for 24 h to obtain a titanium dioxide gel.

[0074] Fabric finishing: same as in Example 1. The relevant parameters of the treated fabric are shown in Table 1.

[0075] Comparative Example 4:

[0076] Nano-titanium dioxide finishing: commercial nano-titanium dioxide powder was diluted in ethanol to prepare a 1 g / L titanium dioxide ethanol solution.

[0077] Fabric finishing: same as in Example 1. The relevant parameters of the treated fabric are shown in Table 1.

[0078] Comparative Example 5:

[0079] Preparation of nano-titanium dioxide sol:

[0080] Tetrabutyl titanate and glacial acetic acid were mixed evenly at room temperature (the mass ratio of tetrabutyl titanate to glacial acetic acid was 10:1), added to a 0.3% by mass hydrochloric acid solution (the mass of the hydrochloric acid solution was 4 times that of tetrabutyl titanate), and the temperature was raised to 50°C and reacted for 30 minutes to obtain a nano-titanium dioxide hydrosol.

[0081] Fabric Finishing: Cotton fabric was dipped in the above solution and then rolled to a 100% roll-off ratio. The fabric was then baked at 100°C for 2 min. The fabric was then dipped in an aqueous solution (60 g / L) of acrylate-based fluorine-free water repellent 1 (Fluorine-free 1) for finishing. A padding and baking process was used: a double dip, double padding, a 100% roll-off ratio, a pre-bake at 100°C for 2 min, and a bake at 150°C for 3 min. The relevant parameters of the treated fabric are shown in Table 1.

[0082] Comparative Examples 6-9:

[0083] The fabrics were not treated with nano-titanium dioxide, but were treated only with a water repellent. The water repellents used were Fluorine-Free 1 (Comparative Example 6), Fluorine-Free 2 (Comparative Example 7), Fluorine-Free 3 (Comparative Example 8), and Fluorine-Free 1 (Comparative Example 9). Other parameters for the water repellent treatment were the same as in Example 1, specifically: the fabrics were treated with a 60 g / L aqueous solution of the water repellent, using a padding and baking process (two dips, two pads, a padding ratio of 100%), pre-baking at 100°C for 2 minutes, and baking at 150°C for 3 minutes. The relevant parameters of the treated fabrics are shown in Table 1.

[0084] Comparative Examples 10-11:

[0085] The fabrics were treated with a water repellent only, without nano-titanium dioxide treatment. The water repellent dosages were 30 g / L (Comparative Example 10) and 150 g / L (Comparative Example 11), respectively. Other water repellent finishing parameters were the same as in Example 1. The relevant parameters of the treated fabrics are shown in Table 1.

[0086] Comparative Example 12:

[0087] The fabric was treated only with titanium dioxide gel, without any water-repellent finish. The titanium dioxide finishing parameters were the same as in Example 1, specifically: a certain amount of nano-titanium dioxide gel was diluted in ethanol to prepare a 1 g / L titanium dioxide ethanol solution. The cotton fabric was then immersed in this solution, rolled to a 100% roll-off ratio, and dried at 100°C for 2 minutes.

[0088] Table 1 Relevant parameters of treated fabrics

[0089]

[0090] Note: Untreated cotton fabric was completely wetted by water before and after washing and drying, with a hydrostatic pressure resistance of 170 mm and a softness of 53.8.

[0091] - indicates complete wetting.

[0092] Product hydrophobicity self-recovery effect: The spray resistance level after washing is the main evaluation index of the water-repellent self-recovery performance of water-repellent fabrics after washing and drying naturally. As can be seen from Examples 1-4 in Table 1, the cotton fabrics obtained by the combined finishing of titanium dioxide and water repellent according to the method provided by the present invention all have good spray resistance after washing and drying naturally (according to the detection characterization method, the highest water repellency level of the fabric is level 5). This is mainly because titanium dioxide can increase the surface roughness of the fabric and has photothermal conversion ability. It can effectively convert light into heat under the same sunlight irradiation, promoting the recovery of the water repellency of the fabric; at the same time, Examples 1-4 also have good static water contact angle, hydrostatic pressure resistance, softness, and spray resistance before washing.

[0093] Comparing Examples 1-4 and Control Example 1 in Table 1, it can be seen that when the amount of titanium dioxide used in the finishing process is too low, its static water contact angle, hydrostatic pressure resistance, and spray resistance before and after washing are all reduced. In particular, the spray resistance after washing is level 2, that is, the water repellent performance of the fabric cannot be restored after washing and drying. The reason is that the light-heat conversion ability of the fabric decreases, and the main reason for the decrease in the static water contact angle is that the surface roughness of the fabric decreases due to insufficient titanium dioxide. Comparing Examples 1-4 and Control Example 2 in Table 1, it can be seen that when the amount of titanium dioxide used in the finishing process is too high, although the water repellent performance and the spray resistance before and after washing are good, the softness of the fabric is greatly reduced.

[0094] By comparing Examples 1-4 and Control Example 3 in Table 1, it can be seen that the titanium dioxide preparation parameters exceed the range provided by the present invention, the obtained titanium dioxide is insufficient, and the spray resistance grade of the fabric after washing and drying naturally is Grade 2, that is, the water repellent property of the fabric cannot be restored after washing and drying naturally.

[0095] By comparing Examples 1-4 and Control Example 4 in Table 1, it can be seen that the spray resistance grade of the fabric treated with commercial titanium dioxide and a water repellent after washing and drying naturally is Level 2, that is, the water repellency of the fabric cannot be restored after washing and drying naturally. The reason is that commercial titanium dioxide has been calcined at high temperature, and its surface lacks chemical groups that can react with the fabric and the water repellent. It is easy to detach from the fabric during washing and cannot exert its photothermal conversion effect.

[0096] By comparing Examples 1-4 and Control Example 5 in Table 1, it can be seen that although the fabric obtained in Control Example 5 has a good static contact angle, hydrostatic pressure resistance and spray resistance before washing, the spray resistance after natural drying after washing is lower than that of the fabrics obtained in Examples 1-4. The main reason is that Control Example 5 directly uses the prepared nano-titanium dioxide hydrosol to impregnate the fabric. During the baking process, the water volatilization rate in the fabric surface treatment liquid is different. Nano-titanium dioxide migrates on the fabric surface with water, resulting in its enrichment in local areas of the fabric and existing in a relatively large volume. This reduces the contact area between titanium dioxide and light, and seriously reduces the photothermal conversion ability of the fabric.

[0097] By comparing Examples 1-4 and Control Example 6 in Table 1, it can be seen that the static contact angle, hydrostatic pressure resistance, and spray resistance before and after washing and natural drying of the fabric obtained without the use of titanium dioxide are all reduced. In particular, the spray resistance level after washing and natural drying is level 2, that is, the water repellent properties of the fabric cannot be restored after washing and natural drying.

[0098] Comparing Example 1 and Control Examples 6-9 in Table 1, it can be seen that the fabrics obtained by finishing without titanium dioxide and changing the type of water repellent only have a slight effect on the static water contact angle and hydrostatic pressure resistance. This is mainly due to the difference in the type of water repellent, which is reflected in the fact that the fluorine-containing water repellent is more effective than the fluorine-free water repellent. However, its spray resistance grade is level 5 before washing and level 3 after natural drying after washing. That is, the water repellency of the fabric cannot be restored after washing and drying naturally.

[0099] Comparing Example 1, Control Example 6, and Comparative Examples 10-11 in Table 1, it can be seen that when the fabric is not finished with titanium dioxide and the amount of water repellent is reduced (Comparative Example 10), the water repellent cannot effectively cover the fabric fibers, and the water repellent properties of the fabric are all reduced; when the amount of water repellent is increased (Comparative Example 11), although the static water contact angle and hydrostatic pressure resistance of Comparative Example 11 are higher than those of Comparative Example 5, the spray resistance of the fabric before and after washing is not improved, but the softness is greatly reduced, indicating that the combined finishing of titanium dioxide and water repellent is not suitable. Only by increasing the amount of water repellent, the water repellent properties of the fabric cannot be restored by naturally drying after washing.

[0100] By comparing Example 1 and Comparative Example 12 in Table 1, it can be seen that when the prepared titanium dioxide gel is used for treatment without a water repellent, the fabric does not have water repellency. This is mainly because the surface of titanium dioxide is rich in hydroxyl groups and is hydrophilic, and the surface of the fabric lacks effective coverage of groups that can reduce its surface energy, which are provided by the water repellent.

[0101] Table 2 Relevant parameters of treated fabrics

[0102]

[0103] Note: Untreated cotton fabric was fully wetted by water before and after washing and drying, with a hydrostatic pressure resistance of 170 mm and a softness of 53.8. Untreated polyester fabric was fully wetted by water before and after washing and drying, with a hydrostatic pressure resistance of 210 mm and a softness of 48.8. Untreated nylon fabric was fully wetted by water before and after washing and drying, with a hydrostatic pressure resistance of 190 mm and a softness of 66.8.

[0104] Comparing Example 1 and Examples 5-11 in Table 2, it can be seen that the fabrics obtained by the combined finishing of titanium dioxide and water repellent according to the method provided by the present invention all have good spray resistance after washing and natural drying, mainly because titanium dioxide can increase the surface roughness of the fabric and has photothermal conversion ability, which can effectively convert light into heat under the same sunlight irradiation, thereby promoting the recovery of the water repellency of the fabric; at the same time, the examples all have good static water contact angle, hydrostatic pressure resistance, softness, and water-repellent level before washing and after washing and drying; the main difference in water repellency between Examples 5-7 and Example 1 is The reason for this is the difference in the type of water repellent. Example 7 is higher than the other examples because the water repellent selected is a fluorine-containing water repellent, which can more effectively reduce the surface energy of the fabric. The difference in water repellency between Examples 8-9 and Example 1 is due to the difference in the type of fabrics selected, where Example 8 is polyester, Example 9 is nylon, and Example 1 is cotton. Different fabrics have slightly different adsorption capacities for water repellents and titanium dioxide. The difference in water repellency between Examples 10-11 and Example 1 is due to the different parameters of the prepared titanium dioxide, which leads to slightly different sizes and contents of titanium dioxide.

Claims

1. A method for preparing a water-repellent textile with self-recovering hydrophobic properties that can be naturally dried after washing, characterized in that: The method comprises: (1) A mixture B of an organic solvent, a reaction catalyst and deionized water is added dropwise to a mixture A of a titanium source and an organic solvent, and the mixture is stirred to react to obtain a nano-titanium dioxide solution, wherein the components of the mixture A include, by mass percentage, 5-20% of a titanium source and 80-95% of an organic solvent; the components of the mixture B include, by mass percentage, 80-90% of an organic solvent, 1-10% of a reaction catalyst, and the remainder is deionized water; the mass ratio of the mixture A to the mixture B is 0.8-1.5:1; the titanium source is at least one of ethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride or titanium trichloride; the organic solvent is at least one of ethanol, propanol or isopropanol; and the reaction catalyst is at least one of glacial acetic acid, nitric acid or hydrochloric acid; (2) removing the organic solvent from the nano-titanium dioxide solution obtained in step (1) by rotary evaporation and aging at room temperature for 12 to 48 hours to obtain a nano-titanium dioxide gel; (3) The fabric is dipped into the ethanol solution of nano-titanium dioxide gel obtained in step (2) and then dried; the concentration of nano-titanium dioxide in the ethanol solution of nano-titanium dioxide gel is 0.5-10 g / L; the rolling rate during the dipping process is 80-150%, the drying temperature is 80-100°C, and the drying time is 1-5 min; (4) The fabric obtained in step (3) is immersed in an aqueous solution of a water repellent and then finished by a padding and baking process, wherein the water repellent comprises at least one of an acrylic fluorine-free water repellent, a silicone fluorine-free water repellent, a polyurethane fluorine-free water repellent or a fluorine-containing water repellent.

2. The method according to claim 1, wherein In step (1), the addition rate of the mixed solution B is 1-10 g / min, the stirring speed is 100-1000 r / min; and the reaction time is 1-8 h.

3. The method according to claim 1, wherein The concentration of the water repellent in step (4) is 50-100 g / L, and the rolling rate in the rolling baking process is 50-150%.

4. The method according to claim 1, wherein In step (4), when finishing the fabric using the pad baking process, the fabric is dipped in the aqueous solution of the water repellent, and then the fabric is pre-baked and then baked. The pre-baking temperature is 80-110°C, the pre-baking time is 1-5 minutes, and the baking temperature is 130-160°C, and the baking time is 1-5 minutes.

5. The method according to any one of claims 1 to 4, characterized in that The fabric comprises one of cotton, wool, linen, polyester and nylon fabrics.

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