Preparation method of nano TiO2 composite fluorescent whitening agent

Abstract

The application discloses a preparation method of a nano TiO2 composite fluorescent whitening agent and relates to the technical field of fluorescent whitening agents. The method comprises the following steps: firstly, one-time condensation is carried out on cyanuric chloride and 4,4'-diamino-stilbene-2,2'-disulfonic acid; secondly, secondary condensation is carried out on diethanolamine, and quaternary ammonium is formed by using epichlorohydrin in the secondary condensation process; finally, tertiary condensation is carried out on amino nanoparticles, so that the nano TiO2 composite fluorescent whitening agent is obtained. The nano TiO2 composite fluorescent whitening agent prepared by the application has the characteristics of good ultraviolet aging resistance and water solubility.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of fluorescent whitening agents, in particular to a preparation method of a nano TiO2 composite fluorescent whitening agent. BACKGROUND

[0002] A fluorescent whitening agent is a fluorescent dye, also known as a white dye, and is widely used in the fields of textiles, papermaking, laundry powder, soap, rubber, plastic, pigment and paint and the like. The fluorescent whitening agent is a complex organic compound, can absorb ultraviolet light and reflect blue-purple visible light, can compensate for the lack of purple and blue light in the product applied, and can increase the total reflected light amount to achieve the effects of whitening and increasing the amount. For printing paper, cultural paper and some industrial paper, whiteness is still an important index. In order to meet the requirements of paper whiteness, on the one hand, chemical bleaching (such as chlorine bleaching or hydrogen peroxide bleaching) is used in the industry; on the other hand, a physical whitening method is used for the straight drop after bleaching, so that the paper can reach the required whiteness. The commonly used physical whitening is to add a fluorescent whitening agent in a certain process during the manufacturing process. The fluorescent whitening agent is a complex organic compound, and according to different chemical structures, it is commonly divided into: diphenylstyrene type, o-oxy naphthone, azole type nitrogen-containing heterocycle and naphthalene dicarboxamide type, and the diphenylstyrene type fluorescent whitening agent is commonly used in the papermaking industry. The diphenylstyrene type fluorescent whitening agent uses the principle of optical complementation to achieve the effect of visual whitening.

[0003] The triazine aminodiphenylstyrene type fluorescent whitening agent is a typical diphenylstyrene type fluorescent whitening agent. The triazine aminodiphenylstyrene type fluorescent whitening agent includes two parts: a continuous conjugated system containing an aromatic ring and one or more substituents; the former has valence electrons that can be excited by ultraviolet light, and when the molecule absorbs ultraviolet light, the valence electrons can be excited to emit fluorescence; the substituents in the molecule can improve the fluorescence characteristics of the conjugated system, and can endow the fluorescent whitening agent with various application properties. However, such fluorescent whitening agents have defects such as poor water solubility, weak fiber binding capacity and easy loss, which limit their effect in paper use. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a nano TiO2 composite fluorescent whitening agent, which solves the following technical problems:

[0005] The existing triazine aminodiphenylstyrene type fluorescent whitening agent has defects such as poor water solubility, weak fiber binding capacity and easy loss.

[0006] The purpose of the present application can be achieved by the following technical scheme:

[0007] The application discloses a preparation method of a nano TiO2 composite fluorescent whitening agent.

[0008] As a further scheme of the application, the NaOH solution is a 1-5wt% NaOH aqueous solution; the adding ratio of cyanuric chloride, acetone, 4,4'-diamino-stilbene-2,2'-disulfonic acid and the NaOH solution is 3.69g: 35-100mL: 3.70g: 22-110mL.

[0009] As a further scheme of the application, the mass ratio of cyanuric chloride to diethanolamine is 3.69: 2.5-2.7.

[0010] As a further scheme of the application, the mass ratio of diethanolamine to epichlorohydrin is 10: 4.4-4.6.

[0011] As a further scheme of the application, the mass ratio of cyanuric chloride to the aminated nano-particle is 3.69: 1-1.5.

[0012] As a further scheme of the application, the preparation method of the aminated nano-particle comprises the following steps:

[0013] A1: nano-titanium dioxide, deionized water and sodium hexametaphosphate are added into a reaction kettle and ultrasonically dispersed uniformly; ammonia water and anhydrous ethanol component one are blended and then added into the reaction kettle and dispersed uniformly; tetraethyl orthosilicate and anhydrous ethanol component two are blended and then added into the reaction kettle and dispersed uniformly; the mixture is aged at room temperature for 5 hours; and the mixture is centrifuged, filtered, washed and dried to obtain the nano-particle;

[0014] A2: the nano-particle, anhydrous ethanol and deionized water are added into a reaction kettle and dispersed uniformly; gamma-aminopropyltriethoxysilane is added and dispersed uniformly; the temperature is controlled to reflux for 9-12 hours; and the mixture is centrifuged, washed and dried to obtain the aminated nano-particle.

[0015] As a further scheme of the present application: the anhydrous ethanol component one and the anhydrous ethanol component two in A1 are both anhydrous ethanol; the ammonia water is 25-28wt% ammonia water; the addition ratio of the nanometer titanium dioxide, the deionized water, the sodium hexametaphosphate, the ammonia water, the anhydrous ethanol component one, the tetraethyl orthosilicate, the anhydrous ethanol component two is 1g: 100-150mL: 0.05g: 25mL: 725-750mL: 1-5mL: 20-25mL.

[0016] As a further scheme of the present application: the addition ratio of the nanoparticle, the anhydrous ethanol, the deionized water, the gamma-aminopropyl triethoxysilane in A2 is 1g: 20-40mL: 10-20mL: 2-4mL.

[0017] The beneficial effects of the present application are:

[0018] (1) The present application prepares a nanometer titanium dioxide suspension by an ultrasonic dispersion method, adds sodium hexametaphosphate as a dispersant, uniformly disperses the titanium dioxide in an ethanol solution containing ammonia water, and adds tetraethyl orthosilicate, hydrolyzes and ages to obtain nanometer titanium oxide molecules coated with silicon dioxide, i.e. nanoparticles; the present application further uses gamma-aminopropyl triethoxysilane to perform aminization treatment on the nanoparticles to obtain aminated nanoparticles. The present application successfully grafts cyanuric chloride on 4,4'-diaminostilbene-2,2'-disulfonic acid by one-step condensation of cyanuric chloride and 4,4'-diaminostilbene-2,2'-disulfonic acid; then uses diethanolamine for two-step condensation to graft tertiary amine groups on 4,4'-diaminostilbene-2,2'-disulfonic acid, and uses epichlorohydrin ring opening grafting in the two-step condensation process to graft quaternary ammonium groups on 4,4'-diaminostilbene-2,2'-disulfonic acid; finally, uses aminated nanoparticles for three-step condensation to obtain a nanometer TiO2 composite fluorescent brightener.

[0019] The application adds titanium dioxide in the fluorescent whitening agent, which not only has the effect of fluorescent whitening, but also has the shielding effect on ultraviolet rays and the film bonding effect of the polymer emulsion, effectively improving the ultraviolet aging resistance of the fluorescent whitening agent. The application loads silica on the surface of nano-titanium dioxide, effectively solving the problem that nano-titanium dioxide is easy to crosslink when directly added, resulting in poor emulsion stability and loss of whiteness. Moreover, silica itself has strong ultraviolet absorption ability, and when added to the fluorescent whitening agent, it forms a network structure with fluorescent molecules and has a shielding effect on fluorescent particles. The application coats silica on the surface of titanium dioxide and performs surface functionalization treatment, which reduces the photocatalytic activity of titanium dioxide without affecting its ultraviolet absorption performance, thereby achieving anti-ultraviolet aging time and effectively avoiding the reaction of the strong oxidizing holes and the strong reducing photo-generated electrons generated after titanium dioxide absorbs ultraviolet rays with O2 and H2O and other substances on the surface of the nanoparticles to generate highly active free radicals. These free radicals react with high molecular materials to break the chemical bonds between molecules, resulting in a decrease in the molecular weight and physical and mechanical properties of the high molecular materials, and finally leading to the degradation of the materials. The application combines the characteristics of fluorescent dye emitting fluorescence and the outer layer substrate of nanoparticles shielding external influences, grafts nanoparticles on dye molecules to prepare fluorescent nanoparticles with good stability and high luminous efficiency. The fluorescent whitening agent prepared by the application effectively improves the light stability and fluorescence intensity of the fluorescent whitening agent, significantly inhibits the yellowing of paper, and effectively improves the surface strength and other mechanical properties of paper.

[0020] (2) The application successfully grafts cyanuric chloride on 4,4'-diaminostilbene-2,2'-disulfonic acid by one-step condensation of cyanuric chloride and 4,4'-diaminostilbene-2,2'-disulfonic acid; then, the secondary condensation is carried out by using diethanolamine to graft tertiary amine groups on 4,4'-diaminostilbene-2,2'-disulfonic acid, and in the process of secondary condensation, the ring-opening grafting of epichlorohydrin is used to graft quaternary ammonium groups on 4,4'-diaminostilbene-2,2'-disulfonic acid. The quaternary ammonium groups and hydroxyl groups generated during the preparation of the fluorescent whitening agent of the application effectively improve the hydrophilicity and fiber binding strength of the fluorescent whitening agent, effectively avoiding the poor water solubility and poor fiber binding of general fluorescent whitening agents, and reducing the easy loss of materials. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0022] The preparation method of the amino-functionalized nanoparticles of Example 1 comprises the following steps:

[0023] A1: 5 g of nanometer titanium dioxide, 500 mL of deionized water, and 0.25 g of sodium hexametaphosphate were added to a reaction kettle and ultrasonically dispersed uniformly, 125 mL of 25 wt% ammonia water and 3625 mL of anhydrous ethanol were blended and then added to the reaction kettle, 5 mL of tetraethyl orthosilicate and 100 mL of anhydrous ethanol were blended and then added to the reaction kettle and dispersed uniformly, and the mixture was allowed to stand at room temperature for 5 h, followed by centrifugation, filtration, washing, and drying to obtain nanoparticles;

[0024] A2: 5 g of the nanoparticles, 100 mL of anhydrous ethanol, and 50 mL of deionized water were added to a reaction kettle and dispersed uniformly, 10 mL of γ-aminopropyltriethoxysilane was added and dispersed uniformly, and the mixture was allowed to reflux at a controlled temperature for 9 h, followed by centrifugation, washing, and drying to obtain amino-functionalized nanoparticles.

[0025] The preparation method of the amino-functionalized nanoparticles of Example 2 comprises the following steps:

[0026] A1: 5 g of nanometer titanium dioxide, 500-750 mL of deionized water, and 0.25 g of sodium hexametaphosphate were added to a reaction kettle and ultrasonically dispersed uniformly, 125 mL of 25 wt% ammonia water and 3700 mL of anhydrous ethanol were blended and then added to the reaction kettle, 15 mL of tetraethyl orthosilicate and 110 mL of anhydrous ethanol were blended and then added to the reaction kettle and dispersed uniformly, and the mixture was allowed to stand at room temperature for 5 h, followed by centrifugation, filtration, washing, and drying to obtain nanoparticles;

[0027] A2: 5 g of the nanoparticles, 150 mL of anhydrous ethanol, and 70 mL of deionized water were added to a reaction kettle and dispersed uniformly, 15 mL of γ-aminopropyltriethoxysilane was added and dispersed uniformly, and the mixture was allowed to reflux at a controlled temperature for 9 h, followed by centrifugation, washing, and drying to obtain amino-functionalized nanoparticles.

[0028] The preparation method of the amino-functionalized nanoparticles of Example 3 comprises the following steps:

[0029] A1: 5 g of nanometer titanium dioxide, 750 mL of deionized water, and 0.25 g of sodium hexametaphosphate were added to a reaction kettle and ultrasonically dispersed uniformly, 125 mL of 25 wt% ammonia water and 3750 mL of anhydrous ethanol were blended and then added to the reaction kettle, 25 mL of tetraethyl orthosilicate and 125 mL of anhydrous ethanol were blended and then added to the reaction kettle and dispersed uniformly, and the mixture was allowed to stand at room temperature for 5 h, followed by centrifugation, filtration, washing, and drying to obtain nanoparticles;

[0030] A2: 5 g nanoparticles, 200 mL anhydrous ethanol, 100 mL deionized water were added into a reaction kettle and uniformly dispersed, 20 mL γ-aminopropyl triethoxysilane was added and uniformly dispersed, the temperature was controlled to reflux for 12 h, centrifuged, washed, and dried to obtain aminated nanoparticles.

[0031] Example 4: A preparation method of a nano-TiO2 composite fluorescent whitening agent, comprising the following steps:

[0032] 3.69 g cyanuric chloride, 100 mL acetone were added into a reaction kettle, the temperature was controlled to 0°C, and stirred and dissolved, 3.70 g 4,4'-diaminostilbene-2,2'-disulfonic acid, 100 mL 1 wt% NaOH aqueous solution were blended and then added into the reaction kettle, the pH value of the system was maintained to be 5 during the adding process, and reacted for 2 h, 2.5 g diethanolamine was added, the pH value was controlled to be 7, and reacted for 3 h, the temperature was controlled to be 75°C, 1.1 g epichlorohydrin was added, and reacted for 3 h, the temperature was controlled to be 85°C, 1-1.5 g aminated nanoparticles prepared in Example 1 were added, the pH value was adjusted to be 7, acetone was removed by rotary evaporation, and reacted for 5 h, cooled, washed with anhydrous ethanol and acetone, recrystallized with ethanol, and dried to obtain a nano-TiO2 composite fluorescent whitening agent.

[0033] Example 5: A preparation method of a nano-TiO2 composite fluorescent whitening agent, comprising the following steps:

[0034] 3.69 g cyanuric chloride, 100 mL acetone were added into a reaction kettle, the temperature was controlled to 0°C, and stirred and dissolved, 3.70 g 4,4'-diaminostilbene-2,2'-disulfonic acid, 100 mL 1 wt% NaOH aqueous solution were blended and then added into the reaction kettle, the pH value of the system was maintained to be 5 during the adding process, and reacted for 2 h, 2.5 g diethanolamine was added, the pH value was controlled to be 7, and reacted for 3 h, the temperature was controlled to be 75°C, 1.1 g epichlorohydrin was added, and reacted for 3 h, the temperature was controlled to be 85°C, 1-1.5 g aminated nanoparticles prepared in Example 1 were added, the pH value was adjusted to be 7, acetone was removed by rotary evaporation, and reacted for 5 h, cooled, washed with anhydrous ethanol and acetone, recrystallized with ethanol, and dried to obtain a nano-TiO2 composite fluorescent whitening agent.

[0035] Example 6: A preparation method of a nano-TiO2 composite fluorescent whitening agent, comprising the following steps:

[0036] Into a reaction vessel were added 3.69 g of cyanuric chloride and 100 mL of acetone, and the temperature was controlled at 0°C while stirring and dissolving. Then, 3.70 g of 4,4'-diaminostilbene-2,2'-disulfonic acid and 100 mL of 1 wt% NaOH aqueous solution were added after being mixed, and the pH of the system was maintained at 5 during the addition. The reaction was allowed to proceed for 2 h, and then 2.5 g of diethanolamine was added while controlling the pH at 7. The reaction was allowed to proceed for 3 h, and then 1.1 g of epichlorohydrin was added while controlling the temperature at 75°C. The reaction was allowed to proceed for 3 h, and then 1 g of the aminated nanoparticles prepared in Example 3 was added while adjusting the pH to 7. Acetone was removed by rotary evaporation, and the reaction was allowed to proceed for 5 h. After cooling, the product was washed with anhydrous ethanol and acetone, recrystallized from ethanol, and dried to obtain a nano-TiO2 composite fluorescent whitening agent.

[0037] The preparation method of the nanoparticles of Comparative Example 1 includes the following steps:

[0038] Into a reaction vessel were added 5 g of nano-titania, 500 mL of deionized water, and 0.25 g of sodium hexametaphosphate, and the mixture was uniformly dispersed by ultrasonic waves. Then, 125 mL of 25 wt% ammonia water and 3625 mL of anhydrous ethanol were added after being mixed, and the mixture was uniformly dispersed. Then, 5 mL of tetraethyl orthosilicate and 100 mL of anhydrous ethanol were added after being mixed, and the mixture was uniformly dispersed. The mixture was allowed to stand for 5 h at room temperature, and then centrifuged, filtered, washed, and dried to obtain nanoparticles.

[0039] The preparation method of the aminated nanoparticles of Comparative Example 2 includes the following steps:

[0040] Into a reaction vessel were added 5 g of nano-titania, 100 mL of anhydrous ethanol, and 50 mL of deionized water, and the mixture was uniformly dispersed. Then, 10 mL of γ-aminopropyltriethoxysilane was added, and the reaction was allowed to proceed for 9 h while controlling the temperature at reflux. The product was centrifuged, washed, and dried to obtain aminated nanoparticles.

[0041] The preparation method of the nano-TiO2 composite fluorescent whitening agent of Comparative Example 3 includes the following steps:

[0042] Into a reaction vessel were added 3.69 g of cyanuric chloride and 100 mL of acetone, and the temperature was controlled at 0°C while stirring and dissolving. Then, 3.70 g of 4,4'-diaminostilbene-2,2'-disulfonic acid and 100 mL of 1 wt% NaOH aqueous solution were added after being mixed, and the pH of the system was maintained at 5 during the addition. The reaction was allowed to proceed for 2 h, and then 2.5 g of diethanolamine was added while controlling the pH at 7. The reaction was allowed to proceed for 3 h, and then 1.1 g of epichlorohydrin was added while controlling the temperature at 75°C. The reaction was allowed to proceed for 3 h, and then 1 g of the aminated nanoparticles prepared in Comparative Example 1 was added while adjusting the pH to 7. Acetone was removed by rotary evaporation, and the reaction was allowed to proceed for 5 h. After cooling, the product was washed with anhydrous ethanol and acetone, recrystallized from ethanol, and dried to obtain a nano-TiO2 composite fluorescent whitening agent.

[0043] Preparation method of a nano-TiO2 composite fluorescent whitening agent, comprising the following steps:

[0044] Into the reactor 3.69 g cyanuric chloride, 100 mL acetone, control the temperature at 0°C, stirring and dissolving, then add 3.70 g 4,4'-diamino-stilbene-2,2'-disulfonic acid and 100 mL 1 wt% NaOH aqueous solution into the reactor, maintain the pH value of the system at 5 during the adding process, keep the reaction for 2 h, then add 2.5 g diethanolamine, control the pH value at 7, keep the reaction for 3 h, control the temperature at 75°C, add 1.1 g epichlorohydrin, keep the reaction for 3 h, control the temperature at 85°C, add 1 g amino-nanoparticles prepared in Comparative Example 2, adjust the pH value to 7, remove acetone by rotary evaporation, continue the reaction for 5 h, cool, wash with anhydrous ethanol and acetone, recrystallize with ethanol, dry, and obtain the nano-TiO2 composite fluorescent whitening agent.

[0045] Preparation method of a nano-TiO2 composite fluorescent whitening agent, comprising the following steps:

[0046] Into the reactor 3.69 g cyanuric chloride, 100 mL acetone, control the temperature at 0°C, stirring and dissolving, then add 3.70 g 4,4'-diamino-stilbene-2,2'-disulfonic acid and 100 mL 1 wt% NaOH aqueous solution into the reactor, maintain the pH value of the system at 5 during the adding process, keep the reaction for 2 h, then add 2.5 g diethanolamine, control the pH value at 7, keep the reaction for 3 h, control the temperature at 85°C, add 1 g amino-nanoparticles prepared in Comparative Example 1, adjust the pH value to 7, remove acetone by rotary evaporation, continue the reaction for 5 h, cool, wash with anhydrous ethanol and acetone, recrystallize with ethanol, dry, and obtain the nano-TiO2 composite fluorescent whitening agent.

[0047] Performance detection

[0048] (1) UV aging resistance

[0049] a: Preparation of the detection sample: take poplar APMP (alkaline peroxide mechanical pulp), and prepare a 10 wt% solution with deionized water, then add 0.05% EDTA, 1% H2O2, and 0.5% Na2SiO3, adjust the pH value to 10 with EDTA, then keep the reaction at 70°C for 90 min, wash the pulp with deionized water for multiple times, and squeeze out the water. Add the pulp into a sheet former, and cast a sheet with a content of 100 g / m 2The circular paper sample is cut into 80mm*80mm paper sheet, 10% oxidized starch solution is added, and the paper sheet is pasted at 90℃ for 30min. Then the solid content is adjusted to 4%, and the nano TiO2 composite fluorescent whitening agent prepared in examples 4-6 and comparative examples 3-5 is added to prepare a sizing solution. The paper is coated on a coating machine and dried in the dark.

[0050] b: detection step: after the paper sample is dried, it is placed in an ultraviolet aging box for ultraviolet aging test. The output power of the ultraviolet aging box is 5.3mW / cm 2 , the temperature is set to 25℃, the wavelength of the ultraviolet lamp tube is 340nm, the paper sample is laid flat in the box, and the light is irradiated for 40h. The whiteness is detected by YQ-Z-48B whiteness meter; the detection results are shown in table 1.

[0051] Table 1: data statistics table of ultraviolet resistance performance detection of examples 4-6 and comparative examples 3-5

[0052]

[0053] As shown in table 1, the nano TiO2 composite fluorescent whitening agent prepared in the application is added in paper processing, which effectively reduces the yellowing speed of paper after ultraviolet treatment, has excellent ultraviolet aging resistance, and has the characteristics of high light stability and high fluorescent intensity when applied in paper processing.

[0054] (2) tensile strength and burst index: the nano TiO2 composite fluorescent whitening agent prepared in examples 4-6 and comparative examples 3-5 is coated on the surface of paper (paper purchased from Changchun Paper Test Machine Co., Ltd.) (fluorescent whitening agent addition amount 0.5%), and the tensile strength and burst index are tested; the detection results are shown in table 2.

[0055] Table 2: data statistics table of mechanical property detection of examples 4-6 and comparative examples 3-5

[0056]

[0057] As shown in table 2, the nano TiO2 composite fluorescent whitening agent prepared in the application has strong combination with paper fibers, which effectively improves the mechanical properties of the material.

[0058] The above describes one embodiment of the application in detail, but the content described is only the preferred embodiment of the application, and cannot be considered as limiting the scope of the application. Any equivalent changes and improvements made according to the scope of the application should still belong to the patent scope of the application.

Claims

1. A method for preparing a nano-TiO2 composite fluorescent whitening agent, characterized in that, The method comprises the following steps: adding cyanuric chloride and acetone into a reaction kettle, controlling the temperature to be 0-5 ℃, stirring and dissolving, adding 4,4'-diamino-stilbene-2,2'-disulfonic acid and a NaOH solution into the reaction kettle after blending, maintaining the pH value of the system to be 5-6 during the adding process, keeping the reaction for 1-3 h, adding diethanolamine, controlling the pH value to be 7-8, keeping the reaction for 2-4 h, controlling the temperature to be 70-80 ℃, adding epichlorohydrin, keeping the reaction for 2-4 h, controlling the temperature to be 80-90 ℃, adding amino-nanoparticles, adjusting the pH value to be 7-8, removing acetone by rotary evaporation, continuing the reaction for 5 h, cooling, washing with anhydrous ethanol and acetone, recrystallizing with ethanol, drying, and thus obtaining the nano-TiO2 composite fluorescent whitening agent. The preparation method of the amino-nanoparticles comprises the following steps: A1: adding nano-titanium dioxide, deionized water and sodium hexametaphosphate into a reaction kettle and uniformly ultrasonic dispersing, adding ammonia water and anhydrous ethanol component one into the reaction kettle after blending and uniformly dispersing, adding tetraethyl orthosilicate and anhydrous ethanol component two into the reaction kettle after blending and uniformly dispersing, keeping the reaction for 5 h at normal temperature, centrifuging, filtering, washing, and drying, and thus obtaining the nanoparticles; A2: adding the nanoparticles, anhydrous ethanol and deionized water into a reaction kettle and uniformly dispersing, adding γ-aminopropyl triethoxysilane and uniformly dispersing, controlling the temperature to be refluxed and keeping the reaction for 9-12 h, centrifuging, washing, and drying, and thus obtaining the amino-nanoparticles.

2. The preparation method of the nano-TiO2 composite fluorescent whitening agent according to claim 1, characterized in that, The NaOH solution is a 1-5 wt% NaOH aqueous solution; the adding ratio of cyanuric chloride, acetone, 4,4'-diamino-stilbene-2,2'-disulfonic acid and the NaOH solution is 3.69 g: 35-100 mL: 3.70 g: 22-110 mL.

3. The preparation method of the nano-TiO2 composite fluorescent whitening agent according to claim 1, characterized in that, The mass ratio of cyanuric chloride to diethanolamine is 3.69: 2.5-2.

7.

4. The preparation method of the nano-TiO2 composite fluorescent whitening agent according to claim 3, characterized in that, The mass ratio of diethanolamine to epichlorohydrin is 10: 4.4-4.

6.

5. The preparation method of a nano-TiO2 composite fluorescent whitening agent according to claim 3, characterized in that, The mass ratio of cyanuric chloride to amino-nanoparticles is 3.69: 1-1.

5.

6. The method for preparing a nano-TiO2 composite fluorescent whitening agent according to claim 1, characterized in that, In A1, the anhydrous ethanol component one and the anhydrous ethanol component two are both anhydrous ethanol; the ammonia water is 25-28 wt% ammonia water; the adding ratio of nano-titanium dioxide, deionized water, sodium hexametaphosphate, ammonia water, anhydrous ethanol component one, tetraethyl orthosilicate, anhydrous ethanol component two is 1 g: 100-150 mL: 0.05 g: 25 mL: 725-750 mL: 1-5 mL: 20-25 mL.

7. The preparation method of a nano-TiO2 composite fluorescent whitening agent according to claim 1, characterized in that, In A2, the adding ratio of nanoparticles, anhydrous ethanol, deionized water and γ-aminopropyl triethoxysilane is 1 g: 20-40 mL: 10-20 mL: 2-4 mL.

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