A kind of deepening agent and preparation method thereof

Abstract

The present invention provides a darkening agent and a preparation method thereof, and relates to the technical field of textile printing and dyeing auxiliaries. The darkening agent of the present invention comprises components: a silane coupling agent, methyl methacrylate, hydroxylamine sulfate, triethanolamine, a surfactant, an antibacterial agent, a pH regulator, a solvent and water. After reacting with a silane coupling agent, methyl methacrylate and an organic solvent, a grafting reaction with hydroxylamine sulfate and triethanolamine is performed, so that the organic silicon and the triethanolamine are friendly combined at the molecular level, and a specific proportion of surfactants are added. Under the premise of being able to increase the softness of the fabric, the components are mutually compatible. Under the action of a suitable reaction temperature and reaction time, the use of the darkening agent simultaneously enables the fabric to have high safety of darkening, brightening, friction fastness, and reduced yellowing of the fabric, and the prepared darkening agent has the significant advantages of high stability.

Description

Technical Field

[0001] The invention belongs to the technical field of textile printing and dyeing auxiliaries, and particularly relates to a darkening agent and a preparation method thereof. Background Art

[0002] The discharge of printing and dyeing wastewater is a severe challenge facing the printing and dyeing industry. Energy consumption, water consumption and sewage discharge account for a large part of the fabric dyeing and finishing processing costs. Reducing the discharge of printing and dyeing wastewater is necessary to reduce processing procedures and reduce processing costs. Reducing the use of dyes can effectively reduce the discharge of printing and dyeing wastewater, and fabric deepening can effectively reduce the use of dyes. There are three ways to deepen the fabric: (1) making the surface of the fabric slightly rough, including chemical etching, physical etching, and using post-processing additives to give the fiber surface fine bumps; (2) increasing the dye uptake rate on the fabric, including chemical modification of the fiber surface to increase the fiber's affinity for the dye, changing the dye properties, and selecting dyes with high affinity and good lifting properties. Select appropriate auxiliaries and dyeing processes; (3) coating the surface of the dyed fabric with a low refractive index resin to reduce the surface reflectivity.

[0003] Among them, the research on low refractive index resins is mostly concentrated on silicone resins, organic fluorine resins, polyurethanes and polyurethane resins. Silicone resins are low-priced, pollution-free, and have good film-forming properties on the surface of fabrics. In addition, silicone resins can obtain excellent darkening and soft feel by introducing appropriate chain segments and group modifications. In the current dyeing process, due to the higher cloth speed and smaller bath ratio, the darkening agent not only needs a good darkening effect, but also a good feel of the fabric after use, and also requires excellent stability.

[0004] Chinese invention patent CN114960211A discloses a silicone softener and a preparation method thereof, which includes components of hydrogen-terminated silicone oil, epoxy polyether, aminoalkane, organic solvent, silicone emulsion and non-ionic surfactant. After use, the fabric has a good feel and is hydrophilic, easy to wash, reduces yellowing of the fabric, and has good stability. Chinese invention patent CN101446038B discloses a fabric darkening and brightening agent, which comprises amino silicone oil, introducing N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane functional groups into the amino silicone oil structure; using octamethylcyclotetrasiloxane or a mixture of methylcyclosiloxane, or linear hydroxyl-terminated polydimethylsiloxane and aminoethylaminopropylmethyldimethoxysilane to polymerize into an amino silicone oil under the action of a catalyst, and then emulsifying into an emulsion of a water system under the action of a surfactant, and then adding a determined proportion of a cationic polyurethane resin emulsion or a cationic acrylic resin emulsion to obtain the fabric darkening and brightening agent; when potassium hydroxide is used as a catalyst, the reaction temperature is 140-160°C; when tetramethoxyammonium hydroxide is used as a catalyst, the reaction temperature is 80-95°C.

[0005] Although there have been a lot of research on darkening agents, conventional darkening agents on the market still have the following problems: (1) The hand feel and darkening effect cannot be taken into account at the same time, and the darkening effect is poor even if the hand feel is good; (2) The stability is poor, and problems such as demulsification and roller sticking are prone to occur during use; (3) The glossiness of the fabric surface decreases after finishing, and the color becomes dull.

[0006] In order to solve the above problems, the present invention provides a new type of high-stability, high-feel and high-safety deepening, brightening and darkening agent, which has an excellent soft and smooth comprehensive feel, can give thick cotton work cloth an excellent soft and transparent feel, and the fabric after finishing has a significant deepening and brightening effect, while not affecting the hydrophilicity of the fabric, the use process is safe, energy-saving and consumption-reducing, and the production cost is reduced. Summary of the invention

[0007] Based on the deficiencies of the prior art, the present invention aims to provide a new type of darkening and brightening agent with high stability, high feel and high safety, and a preparation method of the darkening agent.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] In one aspect, the present invention provides a darkening agent, comprising the following components in parts by weight:

[0010] Silane coupling agent 10-30 parts;

[0011] 5-12 parts of methyl methacrylate;

[0012] 2-6 parts of hydroxylamine sulfate;

[0013] 5-10 parts of triethanolamine;

[0014] 5-10 parts of surfactant;

[0015] Antibacterial agent 0.1-2 parts;

[0016] 1-5 parts of pH regulator;

[0017] 10-20 parts of solvent;

[0018] and 100-150 parts of water.

[0019] Preferably, the silane coupling agent is selected from at least two of dimethyldichlorosilane, methylcyclotetrasiloxane, polydimethylsiloxane, cyclohexylmethyldimethoxysilane, and γ-diethylenetriaminepropylmethyldimethoxysilane.

[0020] Further preferably, the silane coupling agent is selected from at least two of dimethyldichlorosilane, methylcyclotetrasiloxane, polydimethylsiloxane, and cyclohexylmethyldimethoxysilane.

[0021] More preferably, when the silane coupling agent is a mixture of dimethyldichlorosilane, methylcyclotetrasiloxane, polydimethylsiloxane and cyclohexylmethyldimethoxysilane, the weight ratio thereof is 2-6:8-12:2-6:2-6.

[0022] Preferably, the surfactant is a mixture of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant is a polyoxyethylene surfactant selected from at least one of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether; the anionic surfactant is selected from at least one of polyacrylamide and fatty acid salt.

[0023] Further preferably, the weight ratio of the nonionic surfactant to the anionic surfactant is 0.8-1.2:1.

[0024] More preferably, the EO number of the alkylphenol polyoxyethylene ether (APEO) is 7-10.

[0025] More preferably, the molecular weight of the polyacrylamide is 8-10 million.

[0026] Preferably, the antibacterial agent of the present invention refers to a chemical substance that can keep the growth or reproduction of microorganisms such as bacteria, fungi, yeasts, viruses, etc. below the necessary level; and is selected from at least one of ASAP, nanosilver, quaternary ammonium salts, titanium dioxide, and magnesium hydroxide.

[0027] Preferably, the pH adjuster is any common pH adjuster in the art, and more preferably at least one of glacial acetic acid, ammonium sulfate, an acetate buffer system, a phosphate buffer system, and an ammonium sulfate buffer system.

[0028] Preferably, the solvent is selected from at least one of isopropanol, ethylene glycol, glycerol, ethylene glycol butyl ether, dimethylformamide, and ethylene glycol ethyl ether.

[0029] More preferably, the solvent is selected from at least one of isopropyl alcohol, ethylene glycol, dimethylformamide, and ethylene glycol ethyl ether.

[0030] In another aspect, the present invention provides a method for preparing the above-mentioned darkening agent, comprising the steps of:

[0031] (1) uniformly mixing a silane coupling agent, methyl methacrylate and 50-80% by weight of a solvent, and reacting at 60-80° C. for 4-12 hours to obtain a mixture;

[0032] (2) mixing the mixture in step (1) with hydroxylamine sulfate and the remaining weight portion of solvent, heating to 90-120° C. and reacting for 4-8 hours;

[0033] (3) Continue to add triethanolamine and water, and stir to react for 2-4 hours;

[0034] (4) After cooling, a surfactant, an antibacterial agent, and a pH adjuster are added and then kept warm to continue the reaction to obtain a darkening agent.

[0035] Preferably, in step (1), the reaction temperature is 65-75° C., the stirring reaction is carried out for 6-10 hours, the weight of the added solvent is 60-70% of the total weight of the solvent; and the stirring speed is 120-240 r / min.

[0036] Preferably, in step (2), the reaction temperature is 90-110° C., and the stirring reaction is carried out for 5-6 hours; the stirring speed is the same as that in step (1).

[0037] Preferably, in step (3), the water is added multiple times, and more preferably, the water is added 3-5 times within 10-30 minutes.

[0038] Preferably, in step (4), the cooling is to 40-50° C. and the reaction is stirred for 30-90 min.

[0039] Preferably, in steps (3)-(4), the reactions are all carried out under stirring conditions at a rotation speed of 180-240 r / min.

[0040] Finally, the present invention provides the use of the above-mentioned darkening agent in fabric treatment to improve the depth, brightness, vividness, smoothness and softness of fabric.

[0041] Preferably, the amount of the darkening agent used in the application is 10-50 g / L.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The darkening agent of the present invention significantly improves the depth and brightness of various fabrics, including polyester fabrics, all-cotton tarpaulin, and all-cotton woven fabrics, through the interaction between silane coupling agents, methacrylates, and hydroxylamine sulfate, and has no color change on light-colored fabrics, little effect on whiteness, little effect on fastness, and good water-washing resistance;

[0044] 2. The darkening agent of the present invention is introduced into a properly compounded anionic surfactant and a nonionic surfactant to improve the hydrophilicity of silane and / or siloxane, making it easy to emulsify. The prepared darkening agent can give the fabric a higher degree of softness, smoothness and comfort;

[0045] 3. The darkening agent of the present invention not only has good darkening and brightening effects, but is also safe to use, has no toxic side effects, and has good stability. DETAILED DESCRIPTION

[0046] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of protection claimed in this application, and those skilled in the art can make various changes and modifications to the invention of this application based on the disclosed content, which should also fall within the scope of protection claimed in this application.

[0047] The present invention is further described below by way of specific examples. The various chemical reagents used in the examples of the present invention are for illustrative purposes only and are all obtained from conventional commercial channels.

[0048] Example 1

[0049] The components of the darkening agent in parts by weight are: 5 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 5 parts of polydimethylsiloxane, 5 parts of cyclohexylmethyldimethoxysilane, 8 parts of methyl methacrylate, 4 parts of hydroxylamine sulfate, 6 parts of triethanolamine, 4 parts of alkylphenol polyoxyethylene ether (EO number is 8), 4 parts of polyacrylamide (molecular weight is 8 million), 0.5 parts of ASAP, 6 parts of isopropanol, 5 parts of ethylene glycol, 2 parts of dimethylformamide, 1.5 parts of glacial acetic acid, and 120 parts of water.

[0050] The preparation method of the darkening agent comprises the following steps:

[0051] (1) mixing silane coupling agent (5 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 5 parts of polydimethylsiloxane, 5 parts of cyclohexylmethyldimethoxysilane), 8 parts of methyl methacrylate, 4.2 parts of isopropanol, 3.5 parts of ethylene glycol, and 1.4 parts of dimethylformamide, stirring at 70° C. and 180 r / min for 8 hours to obtain a mixture;

[0052] (2) The mixture in step (1) was mixed evenly with 4 parts of hydroxylamine sulfate, 1.8 parts of isopropanol, 1.5 parts of ethylene glycol, and 0.6 parts of dimethylformamide, and the mixture was stirred at 180 r / min and heated to 110° C. for reaction for 6 h;

[0053] (3) Add 6 parts of triethanolamine and water under stirring at 180 r / min, wherein the water is added in 4 equal portions, with an interval of 5 min between each addition of water, and then keep the temperature at 110°C and stir at 180 r / min for 3 h;

[0054] (4) Continue stirring, cool to 45°C, add surfactant (alkylphenol polyoxyethylene ether, polyacrylamide), antibacterial agent (ASAP), pH adjuster (glacial acetic acid), keep stirring at 45°C and continue to react for 50 minutes to obtain a darkening agent.

[0055] Example 2

[0056] The components of the darkening agent in parts by weight are: 2 parts of dimethyldichlorosilane, 8 parts of methylcyclotetrasiloxane, 2 parts of polydimethylsiloxane, 3 parts of cyclohexylmethyldimethoxysilane, 5 parts of methyl methacrylate, 2 parts of hydroxylamine sulfate, 5 parts of triethanolamine, 2 parts of alkylphenol polyoxyethylene ether (EO number is 8), 3 parts of polyacrylamide (molecular weight is 8 million), 0.3 parts of ASAP, 5 parts of isopropanol, 5 parts of ethylene glycol, 1.5 parts of glacial acetic acid, and 100 parts of water.

[0057] The preparation method of the darkening agent comprises the following steps:

[0058] (1) mixing a silane coupling agent (2 parts of dimethyldichlorosilane, 8 parts of methylcyclotetrasiloxane, 2 parts of polydimethylsiloxane, 3 parts of cyclohexylmethyldimethoxysilane), 5 parts of methyl methacrylate, 3.5 parts of isopropanol, and 3.5 parts of ethylene glycol, and stirring at 60° C. and 180 r / min for 12 h to obtain a mixture;

[0059] (2) The mixture in step (1) was mixed evenly with 2 parts of hydroxylamine sulfate, 1.5 parts of isopropanol, and 1.5 parts of ethylene glycol, and the mixture was stirred at 180 r / min and heated to 90° C. for reaction for 8 h;

[0060] (3) Add 5 parts of triethanolamine and water under stirring at 180 r / min, wherein the water is added in 4 equal portions, with an interval of 5 min between each addition of water, and then keep the temperature at 90°C and stir at 180 r / min for 4 h;

[0061] (4) Continue stirring, cool to 40°C, add surfactants (alkylphenol polyoxyethylene ether, polyacrylamide), antibacterial agent (ASAP), and pH adjuster (glacial acetic acid), and continue to react at 40°C with stirring for 90 minutes to obtain a darkening agent.

[0062] Example 3

[0063] The components of the darkening agent in parts by weight are: 6 parts of dimethyldichlorosilane, 12 parts of methylcyclotetrasiloxane, 6 parts of polydimethylsiloxane, 6 parts of cyclohexylmethyldimethoxysilane, 12 parts of methyl methacrylate, 6 parts of hydroxylamine sulfate, 10 parts of triethanolamine, 5 parts of alkylphenol polyoxyethylene ether (EO number is 8), 5 parts of polyacrylamide (molecular weight is 8 million), 0.3 parts of ASAP, 10 parts of isopropanol, 10 parts of ethylene glycol, 5 parts of glacial acetic acid, and 150 parts of water.

[0064] The preparation method of the darkening agent comprises the following steps:

[0065] (1) mixing silane coupling agent (6 parts of dimethyldichlorosilane, 12 parts of methylcyclotetrasiloxane, 6 parts of polydimethylsiloxane, 6 parts of cyclohexylmethyldimethoxysilane), 12 parts of methyl methacrylate, 7 parts of isopropanol and 7 parts of ethylene glycol, stirring at 80° C. and 180 r / min for 10 hours to obtain a mixture;

[0066] (2) The mixture in step (1) was mixed evenly with 6 parts of hydroxylamine sulfate, 3 parts of isopropanol, and 3 parts of ethylene glycol, and the mixture was stirred at 180 r / min and heated to 120° C. for reaction for 6 h;

[0067] (3) Add 10 parts of triethanolamine and water under stirring at 180 r / min, wherein the water is added in 4 equal portions, with an interval of 5 min between each addition of water, and then keep the temperature at 120°C and stir at 180 r / min for 3 h;

[0068] (4) Continue stirring, cool to 50°C, add surfactant (alkylphenol polyoxyethylene ether, polyacrylamide), antibacterial agent (ASAP), pH adjuster (glacial acetic acid), and continue to react at 50°C with stirring for 30 minutes to obtain a darkening agent.

[0069] Example 4

[0070] The components of the darkening agent in parts by weight are: 5 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 5 parts of polydimethylsiloxane, 5 parts of cyclohexylmethyldimethoxysilane, 8 parts of methyl methacrylate, 4 parts of hydroxylamine sulfate, 6 parts of triethanolamine, 4 parts of alkylphenol polyoxyethylene ether (EO number is 10), 4 parts of polyacrylamide (molecular weight is 8 million), 2 parts of fatty alcohol polyoxyethylene ether, 0.5 parts of ASAP, 6 parts of isopropanol, 5 parts of ethylene glycol, 2 parts of dimethylformamide, 2 parts of glacial acetic acid, and 120 parts of water.

[0071] The preparation method of the darkening agent comprises the following steps:

[0072] (1) mixing silane coupling agent (5 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 5 parts of polydimethylsiloxane, 5 parts of cyclohexylmethyldimethoxysilane), 8 parts of methyl methacrylate, 4.2 parts of isopropanol, 3.5 parts of ethylene glycol, and 1.4 parts of dimethylformamide, stirring at 80° C. and 240 r / min for 4 hours to obtain a mixture;

[0073] (2) The mixture in step (1) was mixed evenly with 4 parts of hydroxylamine sulfate, 1.8 parts of isopropanol, 1.5 parts of ethylene glycol, and 0.6 parts of dimethylformamide, and the mixture was stirred at 240 r / min and heated to 110° C. for reaction for 5 h;

[0074] (3) Add 6 parts of triethanolamine and water under stirring at 240 r / min, wherein the water is added in 3 equal portions, with an interval of 10 min between each addition of water, and then keep the temperature at 110°C and stir at 180 r / min for 4 h;

[0075] (4) Continue stirring, cool to 50°C, add surfactant (alkylphenol polyoxyethylene ether, polyacrylamide, fatty alcohol polyoxyethylene ether), antibacterial agent (ASAP), pH adjuster (glacial acetic acid), keep at 50°C, stir at 180 r / min and continue to react for 90 minutes to obtain a darkening agent.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that the components of the darkening agent do not contain dimethyldichlorosilane and methylcyclotetrasiloxane, and the other parameters and preparation methods are the same.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that the weight ratio of the silane coupling agent component of the darkening agent is different, 13 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 1 part of polydimethylsiloxane, and 1 part of cyclohexylmethyldimethoxysilane, and the weight ratio is 13:10:1:1. The other parameters and preparation methods are the same.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that the amount of alkylphenol polyoxyethylene ether as a component of the darkening agent is 0.5 parts, and the other parameters and preparation methods are the same.

[0082] Comparative Example 4

[0083] The difference from Example 1 is that the component surfactant of the darkening agent, the anionic surfactant is replaced by 32 parts of sodium dodecylbenzene sulfonate, and no nonionic surfactant is contained. The other parameters and preparation methods are the same.

[0084] Comparative Example 5

[0085] The difference from Example 1 is that the preparation method of the darkening agent is different. Step (1) is: silane coupling agent (5 parts of dimethyldichlorosilane, 10 parts of methylcyclotetrasiloxane, 5 parts of polydimethylsiloxane, 5 parts of cyclohexylmethyldimethoxysilane), 8 parts of methyl methacrylate, 4.2 parts of isopropanol, 3.5 parts of ethylene glycol, and 1.4 parts of dimethylformamide are mixed evenly, and the mixture is stirred at 150° C. and 180 r / min for 8 hours.

[0086] The remaining parameters and preparation steps were the same.

[0087] Comparative Example 6

[0088] Different from Example 1, the preparation method of the darkening agent is different, and step (2) and step (3) are combined, specifically: the mixture in step (1) is evenly mixed with 4 parts of hydroxylamine sulfate, 1.8 parts of isopropanol, 1.5 parts of ethylene glycol, 0.6 parts of dimethylformamide, 6 parts of triethanolamine and all the water, stirred at 180 r / min, heated to 110° C., and reacted for 9 hours.

[0089] The remaining parameters and preparation steps were the same.

[0090] Experiment 1: Test formula of the darkening agent after padding treatment on different types of fabrics: Darkening agent: Xg / l (see Table 1 for details), working solution pH value: 4-6; Fabric: black polyester cloth, black cotton stretch cloth;

[0091] Process: two dips and two rolls (liquid rate is about 70%) → shaping (cotton: 160℃×90s, polyester: 180℃×90s).

[0092] Table 1

[0093]

[0094] It can be seen from the above table that the darkening agent of the present invention has an excellent darkening effect on polyester fabric / cotton fabric, which is obviously better than the representative darkening agent on the market.

[0095] Experiment 2: Test on the brightening effect of darkening agent on cotton fabric after padding treatment

[0096] Formula: Darkening agent: Xg / l (see Table 2 for details), working solution PH value: 4-6; Fabric: orange cotton woven fabric;

[0097] Process: two dips and two rolls (liquid rate is about 70%) → shaping (cotton: 160℃×90s);

[0098] Note: Vividness rating standard: The rating is divided into 1-5 levels, 1 is the worst vividness, and 5 is the best vividness.

[0099] Table 2

[0100]

[0101]

[0102] As can be seen from the above table, the darkening agent of the present invention has an excellent brightening effect on bright fabrics, which is better than the representative darkening agent on the market. Experiment 3 The effect of the darkening agent on the friction fastness of fabrics after padding treatment Test formula: Darkening agent: Xg / l (see Table 3 for details), working solution pH value: 4-6; Fabric: black cotton woven fabric;

[0103] Process: two dips and two rolls (liquid rate is about 70%) → shaping (cotton: 160℃×90s).

[0104] Note: Fastness rating standard: The rating is divided into 1-5 levels, 1 is the worst fastness, and 5 is the best fastness.

[0105] Table 3

[0106]

[0107] It can be seen from the above table that, on black cotton, the darkening agent of the present invention has substantially no effect on the wet and dry friction fastness; the decrease in the wet and dry friction fastness of the fabric is significantly less than that of the fabric treated with the representative darkening agent on the market.

[0108] Experiment 4: Yellowing effect of darkening agent after padding on whitening cloth

[0109] Formula: Darkening agent: Xg / l (see Table 4 for details), working solution PH value: 4-6; Fabric: 40*40 pure cotton whitening woven fabric;

[0110] Process: two dips and two rolls (liquid rate is about 70%) → shaping (cotton: 160℃×90s).

[0111] Table 4

[0112]

[0113] It can be seen from the above table that the fabric after padding treatment with the darkening agent of the present invention has substantially no yellowing; and the effect on whiteness is significantly smaller than that of the representative darkening agents on the market.

[0114] Experiment 5: Stability test of the darkening agent

[0115] Formula: Darkening agent 100g / l (see Table 5 for details), other conditions are shown in Table 5;

[0116] The comprehensive stability judgment criteria are:

[0117] High safety judgment standard: at pH = 11, temperature 70°C, speed 2000rpm / min, keep warm for 30min and stand for 7d;

[0118] Medium safety judgment standard: at pH = 10.5, temperature 70°C, rotation speed 2000rpm / min, keep warm for 20 minutes and stand for 7 days;

[0119] Basic safety judgment standard: at pH = 9, temperature of 50°C, rotation speed of 2000rpm / min, keep stable for 10 minutes, and stand stable for 7 days.

[0120] In Table 5, in addition to the comprehensive stability, the test methods for other co-bath stability are as follows: 100 g / l of the darkening agent sample and X g / L of other samples (see Table 5 for specific amounts) are mixed together to form a working solution. If it is stable after 7 days, it is stable, otherwise it is unstable.

[0121] Table 5

[0122]

[0123]

[0124] As can be seen from the table above, the new cotton is soft without yellowing and the darkening agent has excellent stability.

[0125] Finally, it should be said that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A darkening agent, characterized in that: Including components by weight: Silane coupling agent 15-25 parts; 5-8 parts of methyl methacrylate; 2-4 parts of hydroxylamine sulfate; 5-6 parts of triethanolamine; 5-8 parts of surfactant; Antibacterial agent 0.3-0.5 parts; 1.5-2 parts of pH regulator; 10-13 parts of solvent; and 100-120 parts of water; The silane coupling agent is a mixture of dimethyldichlorosilane, methylcyclotetrasiloxane, polydimethylsiloxane and cyclohexylmethyldimethoxysilane, and the weight ratio thereof is 2-6:8-12:2-6:2-6; The surfactant is a mixture of a nonionic surfactant and an anionic surfactant, wherein the nonionic surfactant is a polyoxyethylene surfactant selected from at least one of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether; the anionic surfactant is selected from at least one of polyacrylamide and fatty acid salt; The weight ratio of the nonionic surfactant to the anionic surfactant is 0.8-1.2:1; The preparation method of the darkening agent comprises the following steps: (1) uniformly mixing a silane coupling agent, methyl methacrylate and 50-80% by weight of a solvent, and reacting at 60-80° C. for 4-12 hours to obtain a mixture; (2) The mixture in step (1) is mixed evenly with hydroxylamine sulfate and the remaining weight portion of solvent, and the mixture is heated to 90-120° C. and reacted for 4-8 hours; (3) Continue to add triethanolamine and water, keep warm and stir to react for 2-4 hours; (4) After cooling, a surfactant, an antibacterial agent, and a pH adjuster are added and the reaction is continued at a temperature to obtain a darkening agent.

2. The darkening agent according to claim 1, characterized in that: The EO number of the alkylphenol polyoxyethylene ether is 7-10; the molecular weight of the polyacrylamide is 8-10 million.

3. The darkening agent according to claim 1, characterized in that: The antibacterial agent is selected from at least one of ASAP, nanosilver, quaternary ammonium salt, titanium dioxide, and magnesium hydroxide; the pH regulator is selected from at least one of glacial acetic acid, ammonium sulfate, acetic acid buffer system, phosphate buffer system, and ammonium sulfate buffer system; and the solvent is selected from at least one of isopropanol, ethylene glycol, glycerol, ethylene glycol butyl ether, dimethylformamide, and ethylene glycol ethyl ether.

4. The darkening agent according to claim 1, characterized in that: In step (1), the reaction temperature is 65-75° C., the reaction is stirred for 6-10 hours, and the weight of the added solvent is 60-70% of the total weight of the solvent.

5. The darkening agent according to claim 1, characterized in that: In step (2), the reaction temperature is 90-110° C., and the reaction is stirred for 5-6 hours.

6. The darkening agent according to claim 1, characterized in that: In step (4), the temperature is lowered to 40-50°C and the reaction is stirred for 30-90 minutes.

Images