Cationic color fixing agent and preparation method thereof

Abstract

The invention belongs to the technical field of textile dyeing and finishing production, and discloses a cationic color fixing agent and a preparation method thereof.The cationic color fixing agent is obtained by conducting self-polymerization on dimethyl diallyl ammonium chloride and then conducting cross-linking, and in the cross-linking process, the mass ratio of a dimethyl diallyl ammonium chloride self-polymer to a cross-linking agent is 70-80: 1-4; the cross-linking agent is selected from at least one of pentaerythritol triallyl ether, methyl triallyl silane, tetraallyl silane and triallyl (phenyl) silane, the molecular weight of the cationic monomer is firstly increased by synthesizing the self-polymer, and then cross-linking is performed, so that the gel risk is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of textile dyeing and finishing technology, in particular to a cationic fixing agent and a preparation method thereof. BACKGROUND

[0002] In the process of dyeing textiles, cationic fixing agents can prevent dyes from falling off the fabric and hydrolyzing due to ionization, thereby enhancing the color fastness of textiles. However, the structure of traditional fixing agents is mostly linear.

[0003] The adhesion of linear structure to cotton and blended fabrics during fixing treatment needs to be improved. Because the film-forming effect of small molecular or polymer linear structure fixing agent is poor. Moreover, due to the poor density of the polymer film formed by the components of traditional fixing agents after fixing treatment on cotton fabrics, sweat stains can easily penetrate into the fixing polymer film when wearing clothes made of such cotton and blended fabrics, resulting in poor wet fastness and sweat fastness.

[0004] The main structure of traditional cationic fixing agents is only linear polymer or is used only with cross-linking monomers, and the molecular structure of the fixing agent is not directly changed. At present, there are still some shortcomings in the structure of cationic fixing agents. For example, when cationic fixing agents are used with reactive dyes, the film-forming property is often poor due to the linear structure, resulting in poor wet rubbing resistance, washing resistance, and sweat resistance. Therefore, there is an urgent need to propose a solution to solve the above technical problems. However, a three-dimensional cross-linked structure is easy to form a cross-linked polymer during preparation, which can swell but not dissolve in solvents. Therefore, it is difficult to be used in textile dyeing and finishing.

[0005] Chinese patent application 201110370967.5 discloses a micro-cross-linked polydimethyl diallyl ammonium chloride modified fixing agent and a synthesis method thereof. In view of the deficiencies or weaknesses of the existing PDMDAAC fixing agent, a cross-linking monomer triallyl methyl ammonium chloride (TAMAC) is copolymerized with a monomer dimethyl diallyl ammonium chloride (DMDAAC), and by controlling the structure characteristics and relative molecular mass (characteristic viscosity) of the product, a micro-cross-linked copolymer modified PDMDAAC fixing agent with controlled relative molecular mass and structure and a synthesis method thereof are obtained.

[0006] It can be seen that this scheme directly polymerizes triallyl methyl ammonium chloride and dimethyl diallyl ammonium chloride by free radicals, and the product may not only contain the reaction product as described in the scheme, but also a linear structure byproduct composed of DMDAAC and a high cross-linking density byproduct composed of TAMAC.

[0007] The problem this solution aims to solve is: how to provide a color-fixing agent based on DMDAAC with a stereocrosslinked structure. Summary of the Invention

[0008] The purpose of this application is to provide a cationic fixing agent based on DMDAAC. This cationic fixing agent has a good stereocrosslinking structure and its structure is optimized to make it less prone to gelation, which improves its fixing ability and makes it have good stability.

[0009] To achieve the above objectives, this application discloses a cationic fixing agent, wherein the cationic fixing agent is obtained by self-polymerization of dimethyl diallyl ammonium chloride followed by cross-linking, and during the cross-linking process, the mass ratio between the self-polymer of dimethyl diallyl ammonium chloride and the cross-linking agent is 70-80:1-4.

[0010] The crosslinking agent is selected from at least one of pentaerythritol triallyl ether, methyltriallyl silane, tetraallyl silane, and triallyl (phenyl) silane.

[0011] This method obtains a DMDAAC self-polymer with a linear structure through the self-polymerization of DMDAAC. Then, a crosslinking agent is used to crosslink the DMDAAC self-polymer to obtain a fixing agent with a stereocrosslinked structure. Due to the linear structure of the DMDAAC self-polymer, the fixing agent has a network crosslinked structure without the formation of gel due to an overly dense network crosslinked structure.

[0012] Preferably, a functional monomer, diallylamine, is also added during the crosslinking process;

[0013] The mass ratio of dimethyl diallyl ammonium chloride self-polymer to crosslinking agent and functional monomer is 70-80:1-4:8-10.

[0014] Preferably, the dimethyl diallyl ammonium chloride self-polymer is obtained by continuously adding an initiator to dimethyl diallyl ammonium chloride at a temperature of 50-60°C until the viscosity of the system increases to 1000-1500 cp, then stopping the addition of the initiator, and then cooling.

[0015] Preferably, when the crosslinking agent is at least one of pentaerythritol triallyl ether, methyltriallyl silane, and triallyl (phenyl) silane, the viscosity of the dimethyldiallyl ammonium chloride self-polymer is 1000-1500 cp.

[0016] When the crosslinking agent is tetraallylsilane, the viscosity of the dimethyldiallylammonium chloride self-polymer is 1200-1400 cp.

[0017] Furthermore, this application also discloses a method for preparing the above-mentioned cationic fixing agent, comprising the following steps:

[0018] Step 1: Self-polymerize dimethyl diallyl ammonium chloride to obtain dimethyl diallyl ammonium chloride self-polymer;

[0019] Step 2: Mix and crosslink the dimethyl diallyl ammonium chloride self-polymer with a crosslinking agent to obtain a cationic fixing agent.

[0020] Preferably, step 2 specifically includes the following sub-steps:

[0021] Step A1: Mix the dimethyl diallyl ammonium chloride self-polymer, functional monomer, crosslinking agent, phase transfer catalyst and sulfuric acid and heat to 100±5℃;

[0022] Step A2: Add the initiator dropwise to the system of step A1. After the addition is complete, keep it at 100-105℃ for 0.5-1.5h to obtain the cationic fixing agent.

[0023] Preferably, the initiator is selected from at least one of ammonium persulfate, azobisisobutyronitrile, and 2,2-azobis(2-methylpropylimidazolium) hydrochloride;

[0024] The phase transfer catalyst is selected from at least one of tetrabutylammonium bromide, triethylbenzylammonium chloride, and tetrabutylphosphonium bromide.

[0025] Preferably, in step A1, a chelating agent is also added. Step A1 specifically involves mixing dimethyl diallyl ammonium chloride self-polymer, functional monomer, crosslinking agent, chelating agent, phase transfer catalyst, and sulfuric acid and heating to 100±5℃.

[0026] The chelating agent is selected from at least one of hydroxyethylidene diphosphonic acid, ethylenediaminetetraacetic acid, and disodium ethylenediaminetetraacetic acid.

[0027] The beneficial effects of this application are:

[0028] The cationic fixing agent of this application has a good stereocrosslinking structure and the structure is optimized to make it less prone to gelation, which improves its fixing ability and also makes it have good stability.

[0029] This application employs a novel process that first increases the molecular weight of the cationic monomers in the synthesis of self-polymers, then performs cross-linking to reduce the risk of gelation. Furthermore, this application uses a silicon-containing cross-linking agent, resulting in a significant improvement in the hand feel of the treated cotton and its blended fabrics. Detailed Implementation

[0030] The present application will be clearly and completely described below with reference to its embodiments. It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0031] Before demonstrating the embodiments, the preparation and acquisition methods of the raw materials involved in the embodiments shall be explained as follows:

[0032] Dimethyl diallyl ammonium chloride aqueous solution (DMDAAC): purchased from Shandong Polybiotechnology Co., Ltd., with a mass fraction of 60% for dimethyl diallyl ammonium chloride;

[0033] Methyltriallylsilane: purchased from Hubei Xingyan New Materials Technology Co., Ltd.;

[0034] Ammonium persulfate: purchased from Fujian Zhanhua Chemical Co., Ltd.;

[0035] Tetraallylsilane: Purchased from Jiangsu Bost Chemical Technology Co., Ltd.;

[0036] Diallylamine: Purchased from Shandong Polybiotechnology Co., Ltd.

[0037] Example 1

[0038] Step 1: Add dimethyl diallyl ammonium chloride (DMDAAC) to the reactor and stabilize the temperature in the reactor to 55±5℃. Then, add a 20% (w / w) ammonium persulfate aqueous solution dropwise to the reactor. Stop adding the ammonium persulfate aqueous solution when the viscosity of the material in the reactor reaches 1100 cp. Then, circulate a certain amount of cooling water to lower the temperature of the material in the reactor to 25℃, resulting in a 55.9% (w / w) DMDAAC self-polymer solution (it should be noted that the mass fraction of DMDAAC self-polymers in the product is obtained by a saccharimeter).

[0039] Step 2 specifically includes the following sub-steps:

[0040] Step A1: Based on the mass of DMDAAC self-polymer in the 55.9% DMDAAC self-polymer solution, mix 33 parts of DMDAAC self-polymer, 2 parts of methyltriallylsilane, 8 parts of diallylamine, 0.06 parts of ethylenediaminetetraacetic acid, 0.2 parts of tetrabutylammonium bromide, 4 parts of sulfuric acid, and 8 parts of deionized water, and heat to 100±5℃.

[0041] Step A2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC self-polymer to the system in step A1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain cationic fixing agent.

[0042] (It should be noted that in Example 1 and subsequent examples and comparative examples, "parts" specifically refers to the mass parts of the raw materials, that is, the mass ratio of 2 parts of methyltriallylsilane to 8 parts of diallylamine is 2:8).

[0043] Example 2

[0044] Step 1: Add dimethyl diallyl ammonium chloride (DMDAAC) to the reactor and stabilize the temperature in the reactor to 55±5℃. Then, add a 20% ammonium persulfate aqueous solution to the reactor dropwise. Stop adding the initiator when the viscosity of the material in the reactor is 1000 cp. Then, pass cooling water through the reactor to lower the temperature of the material in the reactor to 25℃, and obtain a 55.3% DMDAAC self-polymer solution.

[0045] Step 2 specifically includes the following sub-steps:

[0046] Step A1: Based on the mass of DMDAAC self-polymer in the 55.3% DMDAAC self-polymer solution, mix 38.5 parts of DMDAAC self-polymer, 1 part of methyltriallylsilane, 10 parts of diallylamine, 0.04 parts of ethylenediaminetetraacetic acid, 5 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide, and 10 parts of deionized water, and heat to 100±5℃.

[0047] Step A2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC self-polymer to the system in step A1. After the addition is completed, keep it at 102±2℃ for 1 hour to obtain a cationic fixing agent.

[0048] Example 3

[0049] Step 1: Add dimethyl diallyl ammonium chloride (DMDAAC) to the reactor and stabilize the temperature in the reactor to 55±5℃. Then, add a 20% ammonium persulfate aqueous solution to the reactor dropwise. Stop adding the ammonium persulfate aqueous solution when the viscosity of the material in the reactor is 1500 cp. Then, circulate cooling water to reduce the temperature of the material in the reactor to 25℃, and obtain a 55.2% DMDAAC self-polymer solution.

[0050] Step 2 specifically includes the following sub-steps:

[0051] Step A1: Based on the mass of DMDAAC self-polymer in the 55.2% DMDAAC self-polymer solution, mix 35.75 parts of DMDAAC self-polymer, 4 parts of methyltriallylsilane, 9 parts of diallylamine, 0.08 parts of disodium ethylenediaminetetraacetate, 4.5 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide, and 20 parts of deionized water, and heat to 100±5℃.

[0052] Step A2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC self-polymer to the system in step A1. After the addition is completed, keep it at 102±2℃ for 0.5h to obtain cationic fixing agent.

[0053] Example 4

[0054] The process is basically the same as in Example 1, except that step 2 specifically includes the following sub-steps:

[0055] Step A1: Based on the mass of DMDAAC self-polymer in the 55.9% DMDAAC self-polymer solution, mix 41 parts of DMDAAC self-polymer, 2 parts of methyltriallylsilane, 0.06 parts of ethylenediaminetetraacetic acid, 0.5 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide, and 8 parts of deionized water, and heat to 100±5℃.

[0056] Step A2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC self-polymer to the system in step A1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain cationic fixing agent.

[0057] Example 5

[0058] It is basically the same as Example 1, except that tetraallylsilane is used instead of methyltriallylsilane.

[0059] Example 6

[0060] The process is basically the same as in Example 1, except that tetraallylsilane is used instead of methyltriallylsilane. Specifically, step 1 is as follows: Dimethyldiallylammonium chloride (DMDAAC) is added to the reactor and the temperature in the reactor is stabilized at 55±5°C. Then, a 20% ammonium persulfate aqueous solution is added dropwise to the reactor. When the viscosity of the material in the reactor reaches 1300 cp, the addition of the ammonium persulfate aqueous solution is stopped. Cooling water is then introduced to lower the temperature of the material in the reactor to 25°C, thus obtaining a DMDAAC self-polymer solution.

[0061] Example 7

[0062] The process is basically the same as in Example 1, except that tetraallylsilane is used instead of methyltriallylsilane. Specifically, step 1 is as follows: Dimethyldiallylammonium chloride (DMDAAC) is added to the reactor and the temperature in the reactor is stabilized at 55±5°C. Then, a 20% ammonium persulfate aqueous solution is added dropwise to the reactor. When the viscosity of the material in the reactor reaches 1500 cp, the addition of the ammonium persulfate aqueous solution is stopped. Cooling water is then introduced to lower the temperature of the material in the reactor to 25°C, thus obtaining a DMDAAC self-polymer solution.

[0063] Comparative Example 1

[0064] Step 1: Based on the mass of dimethyl diallyl ammonium chloride in the aqueous solution of dimethyl diallyl ammonium chloride, add 33 parts of dimethyl diallyl ammonium chloride, 8 parts of diallylamine, 0.06 parts of ethylenediaminetetraacetic acid, 0.2 parts of tetrabutylammonium bromide, 4 parts of sulfuric acid, and 8 parts of deionized water to the reaction vessel and mix, then heat to 100±5℃;

[0065] Step 2: Then, add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC dropwise to the reaction vessel. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain the color fixing agent.

[0066] Comparative Example 2

[0067] Step 1: Based on the mass of dimethyl diallyl ammonium chloride in the aqueous solution of dimethyl diallyl ammonium chloride, add 71.5 parts of dimethyl diallyl ammonium chloride (DMDAAC), 8 parts of diallylamine, and 4 parts of sulfuric acid to the reactor. Stabilize the temperature in the reactor to 55±5℃. Then, add a 20% ammonium persulfate aqueous solution dropwise to the reactor. Stop adding the initiator when the viscosity of the material in the reactor reaches 1500 cp. Then, circulate cooling water to lower the temperature of the material in the reactor to 25℃ to obtain the copolymer.

[0068] Step 2 includes the following sub-steps:

[0069] Step A1: Divide the copolymer obtained in Step 1 into a first part and a second part, wherein the mass ratio of the first part to the second part is 55:64;

[0070] The first part of the copolymer was then mixed with 2 parts of methyltriallylsilane, 0.06 parts of ethylenediaminetetraacetic acid, 0.5 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide and 8 parts of deionized water, and heated to 100±5℃.

[0071] Step A2: Add 10 parts of an ammonium persulfate aqueous solution with a mass fraction of 20% and the second part of the copolymer to the system of step A1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain the color fixing agent.

[0072] Comparative Example 3

[0073] Step 1: Add dimethyl diallyl ammonium chloride (DMDAAC) to the reactor and stabilize the temperature in the reactor to 55±5℃. Then, add a 20% ammonium persulfate aqueous solution dropwise to the reactor. When the viscosity of the material in the reactor reaches 1500 cp, stop adding the ammonium persulfate aqueous solution. Then, circulate cooling water to lower the temperature of the material in the reactor to 25℃, and obtain a DMDAAC self-polymer solution with a mass fraction of 56.1%.

[0074] Step 2 specifically includes the following sub-steps:

[0075] Step A1: Based on the mass of DMDAAC self-polymer in a DMDAAC self-polymer solution with a mass fraction of 56.1%, mix 33 parts of DMDAAC self-polymer, 10 parts of diallylamine, 0.06 parts of ethylenediaminetetraacetic acid, 0.2 parts of tetrabutylammonium bromide, 4 parts of sulfuric acid and 8 parts of deionized water, and heat to 100±5℃.

[0076] Step A2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC self-polymer to the system in step A1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain the color fixing agent.

[0077] Comparative Example 4

[0078] Step 1: Based on the mass of dimethyl diallyl ammonium chloride in the aqueous solution of dimethyl diallyl ammonium chloride, add 33 parts of dimethyl diallyl ammonium chloride (DMDAAC), 2 parts of methyltriallylsilane, 8 parts of diallylamine, 0.06 parts of ethylenediaminetetraacetic acid, 4 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide, and 8 parts of deionized water to the reaction vessel and heat to 100±5℃.

[0079] Step 2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC dropwise to the system in Step 1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain the color fixing agent.

[0080] Comparative Example 5

[0081] Step 1: Based on the mass of dimethyl diallyl ammonium chloride in the aqueous solution of dimethyl diallyl ammonium chloride, add 41 parts of dimethyl diallyl ammonium chloride (DMDAAC), 2 parts of methyltriallylsilane, 0.06 parts of ethylenediaminetetraacetic acid, 0.5 parts of sulfuric acid, 0.2 parts of tetrabutylammonium bromide, and 8 parts of deionized water to the reaction vessel and heat to 100±5℃.

[0082] Step 2: Add 10 parts of ammonium persulfate aqueous solution with a mass fraction of 20% and 38.5 parts of DMDAAC aqueous solution with a mass fraction of 60% to the system in Step 1. After the addition is completed, keep it at 102±2℃ for 1.5h to obtain the color fixing agent.

[0083] Performance testing

[0084] The fabrics of bright red knitted pure cotton and bright red knitted polyester-cotton (50% cotton, 50% polyester) were subjected to color-fixing treatment using Examples 1-7 and Comparative Examples 1-5. The process was as follows: color-fixing agent dosage 20 g / L, one dip and one nibble (pressure 0.3 Pa), and setting and drying at 180 ℃ for 120 seconds.

[0085] It should be noted that the dyeing process for the bright red knitted pure cotton is as follows:

[0086] 1. Cut approximately 10g of pre-treated pure cotton fabric;

[0087] 2. Dilute the required red reactive dye (Wuxi Huichang Chemical Dye Co., Ltd.) with water to a dye concentration of 1wt% and set aside.

[0088] 3. Place the fabric and diluted dye into the dyeing cup. The dye amount is 3% (owf), and the liquor ratio is 1:20.

[0089] 4. Add NaCl and NaOH to the staining cup to make their concentrations 60 g / L and 25 g / L, respectively;

[0090] 5. Place the dyeing cup into a high-temperature dyeing machine and set it to 60℃. After 60 minutes, remove the fabric, wash off any excess dye with soap, and dry it. It can then be used for color fixation testing.

[0091] Polyester-cotton red dyeing process:

[0092] 1. Cut approximately 10g of pre-treated polyester-cotton fabric (50% polyester, 50% cotton);

[0093] 2. Dilute the required red disperse dye and red reactive dye (Wuxi Huichang Chemical Dye Co., Ltd.) with water to a dye concentration of 1wt% and 1wt% respectively, and set aside.

[0094] 3. Place the fabric and diluted disperse dye in the dyeing cup. The dye amount is 3% (owf), and the liquor ratio is 1:20.

[0095] 4. Add high-temperature leveling agent (Guangdong Honghao Chemical Co., Ltd.) and glacial acetic acid to the dyeing cup, with concentrations of 1g / L and 0.5g / L respectively;

[0096] 5. Place the dyeing cup into the high-temperature dyeing machine and set it to 130℃. After 60 minutes, take out the fabric and wash it to remove the excess dye. At this point, the dyeing of polyester is complete.

[0097] 6. The above-mentioned fabric and diluted reactive dye are spun into a dyeing cup. The dye amount is 3% (owf) and the liquor ratio is 1:20.

[0098] 7. Add NaCl and NaOH to the staining cup to make their concentrations 60 g / L and 25 g / L, respectively;

[0099] 8. Place the dyeing cup into a high-temperature dyeing machine and set it to 60℃. After 60 minutes, remove the fabric, wash off any excess dye with soap, and dry it. It can then be used for color fixation testing.

[0100] Wash fastness: The color fastness of the fabric samples treated with fixing agents in the above examples and comparative examples was tested according to the national standard GB / T3921-2008 "Textiles - Tests for color fastness - Color fastness to washing". The test results are shown in Table 1 and Table 2.

[0101] Perspiration fastness: The color fastness of the fabric samples treated with color-fixing agents in the above examples and comparative examples was tested according to the national standard GB / T3922-2013 "Textiles - Tests for color fastness - Perspiration fastness". The test results are shown in Table 1 and Table 2.

[0102] Rubbing fastness: The rubbing fastness of the fabric samples treated with fixing agents in the above examples and comparative examples was tested according to the national standard GB / T3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing". The test results are shown in Table 1 and Table 2.

[0103] Immersion fastness: With a liquor ratio of 1:40, the dyed fabrics treated in the above examples and comparative examples were immersed in a 5g / L detergent solution at 100℃ and stirred for 15 minutes. The color of the detergent solution was then observed. A darker color indicates severe dye stripping and color fading, suggesting poor color fastness; conversely, a lighter color indicates better fastness. The test results are shown in Tables 1 and 2.

[0104] Table 1: Colorfastness Test of Bright Red Knitted Cotton

[0105] Table 2: Color Fixation Test of Bright Red Knitted Polyester-Cotton Fabric

[0106] Results analysis:

[0107] 1. As can be seen from Examples 1-3, when the amount of each component in the fixing agent is adjusted slightly, the fixing ability of Examples 1-3 shows a certain degree of fluctuation, but overall, the fluctuation range is relatively small.

[0108] Further observation of Example 4 reveals that when the use of diallylamine was reduced and the amount of DMDAAC self-polymer was increased by the same amount, although the overall proportion of linear structure in the fixing agent did not show a significant change, the fixing ability of Example 4 showed a more obvious downward trend compared to Example 1. Furthermore, observation of its dyeing effect on bright red knitted polyester-cotton showed that its fixing effect on systems with both reactive and disperse dyes decreased by one grade in almost every performance test compared to Example 1 (except for sweat and acid fastness). It is speculated that the reason for this phenomenon may be that the functional monomer (dallylamine) improves the film-forming properties on the fiber surface by adjusting the molecular weight and molecular chain flexibility of the copolymer, and further binds to the fiber (such as cotton cellulose) or dye molecules through hydrogen bonds or van der Waals forces, thereby enhancing the durability of the fixing effect.

[0109] 2. As can be seen from Examples 1 and 5-6, when tetraallylsilane was used to replace methyltriallylsilane in Example 5, the color-fixing ability of Example 5 also decreased significantly compared to Example 1. It is speculated that the reason for this phenomenon may be that when the same viscosity of DMDAAC self-polymer was used in Example 5 and Example 1, the crosslinking agent tetraallylsilane in Example 5 provided more crosslinking points, which made the crosslinking structure of the color-fixing agent more dense. The excessively dense crosslinking points led to a decrease in the stability of the color-fixing agent.

[0110] Further observation of Example 6 shows that when tetraallylsilane is used and the viscosity of DMDAAC self-polymer is increased, the length of the linear structure in the fixing agent is extended, thereby reducing the number of DMDAAC self-polymers and thus reducing the crosslinking density of the fixing agent, thereby improving the stability of the fixing agent and thus improving the fixing ability of Example 6. In addition, since tetraallylsilane has relatively low reactivity, and the chain length of DMDAAC self-polymer is too long, the steric hindrance is too large, which will cause the DMDAAC self-polymer to be unable to crosslink normally.

[0111] 3. As can be seen from Example 1 and Comparative Examples 1 and 3, when Comparative Example 3 directly uses dimethyl diallyl ammonium chloride and diallylamine for copolymerization, a fixing agent with a linear structure and without a cross-linked network structure is obtained. The film-forming effect of the fixing agent with only a linear structure is obviously not as good as that of the cross-linked structure, which leads to a reduction in the fixing effect of Comparative Example 1.

[0112] Further observation of Comparative Example 3 shows that Comparative Example 3 first undergoes self-polymerization of DMDAAC to obtain a linear DMDAAC self-polymer, and then copolymerizes the DMDAAC self-polymer with diallylamine. However, the resulting product is still linear. Therefore, the color-fixing ability of Comparative Example 3 is still significantly different from that of Example 1.

[0113] 4. As can be seen from Example 1 and Comparative Examples 4-5, when Comparative Examples 4-5 directly use dimethyl diallyl ammonium chloride and a crosslinking agent (methyltriallylsilane) for crosslinking, a color-fixing agent with good color-fixing ability cannot be obtained regardless of whether diallylamine is added. The reason is that directly using dimethyl diallyl ammonium chloride and a crosslinking agent for crosslinking results in an excessively high crosslinking density, which in turn causes the color-fixing agent to gel during use, preventing it from achieving its color-fixing effect. In contrast, Example 1 first extends the linear structure through DMDAAC self-polymerization and then performs crosslinking, reducing the risk of gelation. Furthermore, the crosslinked network structure gives the color-fixing agent a good film-forming effect.

[0114] 5. As can be seen from Example 1 and Comparative Example 2, when Comparative Example 2 first copolymerizes dimethyl diallyl ammonium chloride and diallylamine to generate a linear structure, and then crosslinks the copolymer of dimethyl diallyl ammonium chloride and diallylamine with the linear structure to obtain a fixing agent, it can be observed that Comparative Example 2 has a better fixing effect compared with other comparative examples. However, since diallylamine is introduced into the linear structure by copolymerizing with dimethyl diallyl ammonium chloride, its distribution uniformity is reduced compared with the crosslinking method. As a result, the dye in some areas cannot be effectively fixed or is over-adsorbed, thus affecting the fixing ability of the fixing agent.

Claims

1. A cationic fixing agent, characterized in that, The cationic fixing agent is obtained by self-polymerization of dimethyl diallyl ammonium chloride followed by cross-linking, and during the cross-linking process, the mass ratio between the self-polymer of dimethyl diallyl ammonium chloride and the cross-linking agent is 70-80:1-4. The crosslinking agent is selected from at least one of pentaerythritol triallyl ether, methyltriallyl silane, tetraallyl silane, and triallyl (phenyl) silane.

2. The cationic fixing agent according to claim 1, characterized in that, A functional monomer, diallylamine, is also added during the crosslinking process. The mass ratio of dimethyl diallyl ammonium chloride self-polymer to crosslinking agent and functional monomer is 70-80:1-4:8-10.

3. The cationic fixing agent according to claim 1, characterized in that, The dimethyl diallyl ammonium chloride self-polymer is obtained by continuously adding an initiator dropwise to dimethyl diallyl ammonium chloride at a temperature of 50-60°C until the viscosity of the system increases to 1000-1500 cp, then stopping the addition of the initiator, and then cooling.

4. The cationic fixing agent according to claim 2, characterized in that, When the crosslinking agent is at least one of pentaerythritol triallyl ether, methyltriallylsilane, and triallyl (phenyl)silane, the viscosity of the dimethyldiallylammonium chloride selfpolymer is 1000-1500 cp. When the crosslinking agent is tetraallylsilane, the viscosity of the dimethyldiallylammonium chloride self-polymer is 1200-1400 cp.

5. A method for preparing the cationic fixing agent according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Self-polymerize dimethyl diallyl ammonium chloride to obtain dimethyl diallyl ammonium chloride self-polymer; Step 2: Mix and crosslink the dimethyl diallyl ammonium chloride self-polymer with a crosslinking agent to obtain a cationic fixing agent.

6. The method for preparing the cationic fixing agent according to claim 5, characterized in that, Step 2 specifically includes the following sub-steps: Step A1: Mix the dimethyl diallyl ammonium chloride self-polymer, functional monomer, crosslinking agent, phase transfer catalyst and sulfuric acid and heat to 100±5℃; Step A2: Add the initiator dropwise to the system of step A1. After the addition is complete, keep it at 100-105℃ for 0.5-1.5h to obtain the cationic fixing agent.

7. The method for preparing the cationic fixing agent according to claim 6, characterized in that, The initiator is selected from at least one of ammonium persulfate, azobisisobutyronitrile, and 2,2-azobis(2-methylpropylimidazolium) hydrochloride; The phase transfer catalyst is selected from at least one of tetrabutylammonium bromide, triethylbenzylammonium chloride, and tetrabutylphosphonium bromide.

8. The method for preparing the cationic fixing agent according to claim 5, characterized in that, In step A1, a chelating agent is also added. Specifically, step A1 involves mixing dimethyl diallyl ammonium chloride self-polymer, functional monomer, crosslinking agent, chelating agent, phase transfer catalyst, and sulfuric acid and heating to 100±5℃. The chelating agent is selected from at least one of hydroxyethylidene diphosphonic acid, ethylenediaminetetraacetic acid, and disodium ethylenediaminetetraacetic acid.

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