Acid color fixing agent free of phenol and bisphenol substances as well as preparation method and application of acid color fixing agent

Abstract

The invention belongs to the technical field of fabric color fixing agents, and particularly relates to an acidic color fixing agent free of phenol and bisphenol substances as well as a preparation method and application of the acidic color fixing agent. The acidic color fixing agent is characterized by comprising the following components in parts by weight: 25-55 parts of water, 10-35 parts of tannic acid, 1-20 parts of cardanol sulfonic acid, 1-15 parts of aralkyl phenol, 1-5 parts of xylenol, 1-5 parts of formaldehyde, 1-10 parts of bio-based aldehyde, 1-10 parts of acrolein, 1-10 parts of concentrated sulfuric acid, 1-5 parts of acetic acid, 1-10 parts of sodium hydroxide and 1-5 parts of ammonia water. The invention also provides a preparation method of the acidic color fixing agent. The acid color fixing agent has the advantages of high fastness, no color change and small anion and cation conflict risk, can ensure that bisphenol A, B, S, F and AF and phenol are not used, and can meet the requirements of environmental regulations.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fabric fixing agents, and particularly relates to an acid fixing agent free of phenol and bisphenol substances and a preparation method and application thereof. BACKGROUND

[0002] Polyamide fabric has soft hand feeling and good wear resistance, and is widely used, and is usually dyed with acid dyes. Acid dyes have the advantages of complete color spectrum and convenient use, but after being dyed on polyamide fabric, most of the dyes are combined with the fabric by van der Waals force and hydrogen bond due to the small amount of amino groups at the end of polyamide fibers, and the fastness is not good, and the acid dyes contain water-soluble sulfonic acid groups and carboxyl groups, which cause the dyes to be easily washed out, and the more sulfonic acid groups, the worse the fastness of the dyed fabric, therefore, generally, medium and dark polyamide dyed fabrics need to be fixed.

[0003] General fixing principle: (1) the fixing agent forms a film on the surface of polyamide to prevent the diffusion of dyes outward; (2) the repulsion between the sulfonic acid anions of the fixing agent and the dye anions prevents the diffusion of dyes from the fiber outward. The current mainstream fixing agent products take anionic high molecular sulfonate and formaldehyde-free polyamine condensate as the core, and the bio-based fixing system becomes a new direction due to low energy consumption and high safety.

[0004] However, the main problems in the current industry of polyamide acid fixing are: (1) the fixing agent generally contains bisphenol A, B, S, F, AF and phenol, which cannot meet the requirements of environmental regulations; (2) the fixing agent has an unsatisfactory fixing fastness, which cannot meet the fastness requirements of factories; (3) the fixing agent has problems such as large fixing color change; (4) the fixing agent has a high risk of anion-cation conflict, and fixing stains are prone to occur during fixing.

[0005] Chinese invention patent application CN119219911A discloses a bisphenol-free acid fixing agent based on plant extracts and a preparation method thereof, which contains plant polyphenol compounds and chlorine-containing benzene compounds, and contains gallic acid in the ingredients, but a large amount of organic solvents are used in the preparation process, even the ratio of acetone to water reaches 4:1. The fixing agent will have a large amount of organic solvent residues, and the production method is not environmentally friendly, which will cause serious damage to the environment.

[0006] Chinese invention patent application CN116421685A provides a bio-based acidic fixing agent, and a preparation method and application thereof. The acidic fixing agent contains bio-based cardanol sulfonic acid and bio-based aldehyde. The preparation method uses the toxic organic phosphorus compound tributyl ethyl phosphonium bromide and the strongly irritating 4-cyanobenzoic acid, which may have a serious impact on the health of production personnel, and these toxic and irritating substances may also be left in the product, which may pose a potential threat to the health of the personnel using the product.

[0007] Therefore, how to provide an acidic fixing agent that does not cause ion conflict with the dyeing agent, so that it can have the advantages of high fastness and no color change, and at the same time can ensure no bisphenol A, B, S, F, AF and phenol, has become a research hotspot in the field. SUMMARY

[0008] In view of the problems existing in the prior art, the purpose of the present application is to provide an acidic fixing agent without phenol and bisphenol substances, and a preparation method and application thereof. The acidic fixing agent does not cause ion conflict with the dyeing agent, so that it can have the advantages of high fastness and no color change, and at the same time can ensure no bisphenol A, B, S, F, AF and phenol, and can meet the requirements of environmental protection regulations.

[0009] To achieve the above-mentioned purpose of the application, the first aspect of the present application provides an environmentally friendly acidic fixing agent without phenol and bisphenol substances, which comprises the following components by weight: water 25-55 parts, tannic acid 10-35 parts, cardanol sulfonic acid 1-20 parts, aralkyl phenol 1-15 parts, dimethyl phenol 1-5 parts, formaldehyde 1-5 parts, bio-based aldehyde 1-10 parts, propylene aldehyde 1-10 parts, concentrated sulfuric acid 1-10 parts, acetic acid 1-5 parts, sodium hydroxide 1-10 parts and ammonia 1-5 parts.

[0010] Further, the acidic fixing agent comprises the following components by weight: water 30-50 parts, tannic acid 15-30 parts, cardanol sulfonic acid 5-15 parts, aralkyl phenol 3-13 parts, dimethyl phenol 2-4 parts, formaldehyde 1-2 parts, bio-based aldehyde 2-8 parts, propylene aldehyde 1-5 parts, concentrated sulfuric acid 1-5 parts, acetic acid 1-2 parts, sodium hydroxide 1-5 parts and ammonia 1-3 parts.

[0011] In one specific embodiment of the present application, the acidic fixing agent comprises the following components by weight: water 40 parts, tannic acid 20 parts, cardanol sulfonic acid 10 parts, aralkyl phenol 8 parts, dimethyl phenol 3 parts, formaldehyde 1 part, bio-based aldehyde 6 parts, propylene aldehyde 3 parts, concentrated sulfuric acid 3 parts, acetic acid 1 part, sodium hydroxide 3 parts and ammonia 2 parts.

[0012] Further, the aralkyl phenol is selected from one or more of nonyl phenol polyoxyethylene ether, octyl phenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.

[0013] Further, the bio-based aldehyde is selected from one or more of glutaraldehyde, hydroxymethylfurfural, and glycerinaldehyde.

[0014] In a second aspect, the present application provides a preparation method of the acid fixing agent, comprising the following steps: S1, mixing water, tannic acid, cardanol sulfonic acid, aralkyl phenol and dimethyl phenol by weight parts, heating and stirring to obtain a mixed solution; S2, cooling the mixed solution obtained in step S1, adding formaldehyde, bio-based aldehyde and acrolein dropwise, continuously stirring, controlling the reaction temperature, and continuing to stir after the dropwise addition is completed; S3, cooling, adding concentrated sulfuric acid and acetic acid dropwise, continuously stirring, and controlling the reaction temperature; after the dropwise addition is completed, heating and then holding; S4, cooling the reaction solution obtained in step S3, adding sodium hydroxide aqueous solution and ammonia water dropwise, and continuing to stir; S5, cooling to room temperature to obtain the acid fixing agent.

[0015] Further, in step S1, the heating is specifically to 40-50℃, and the stirring time is 20-40min; in step S2, the cooling is specifically to 20-40℃, and the control of the reaction temperature is specifically to control the reaction temperature at 50-70℃, and the stirring time is 45-90min.

[0016] In a specific embodiment of the present application, in step S1, the heating is specifically to 45℃, and the stirring time is 30min; in step S2, the cooling is specifically to 30℃, and the control of the reaction temperature is specifically to control the reaction temperature at 60℃, and the stirring time is 60min.

[0017] Further, in step S3, the cooling is specifically to 40-60℃, the control of the reaction temperature is specifically to control the reaction temperature at 50-70℃, and the heating and then holding is specifically to heat to 80-100℃ and then hold for 1-4h; in step S4, the cooling is specifically to 25-35℃, and the continuous stirring time is 20-40min.

[0018] In a specific embodiment of the present application, in step S3, the cooling is specifically to 50℃, the control of the reaction temperature is specifically to control the reaction temperature at 60℃, and the heating and then holding is specifically to heat to 90℃ and then hold for 3h; in step S4, the cooling is specifically to 30℃, and the continuous stirring time is 30min.

[0019] Further, in step S4, the mass fraction of the sodium hydroxide aqueous solution is 10-50%.

[0020] In a third aspect, the present application provides the use of the acid fixing agent or the acid fixing agent prepared by the preparation method in the dyeing of polyamide.

[0021] The beneficial effects of the present application include: 1. No phenol, bisphenol A, B, S, F, AF, in line with environmental requirements; 2. The fixing agent has excellent water washing, perspiration, water immersion fastness, which can be comparable to or slightly better than non-environmental fixing agent; 3. Minimal impact on color change and yellowing, which can be applied to sensitive colors and white ground printed fabrics; 4. The fixing agent has a small risk of cation conflict, and is not prone to produce fixing spots; 5. It has excellent white ground anti-staining performance and can be applied to white ground printed fabrics. DETAILED DESCRIPTION

[0022] Terms and statements of the present application: 1. The articles "a", "an", and "the": unless otherwise expressly specified to one (a kind) of objects, include plural objects.

[0023] 2. Numerical range: unless otherwise expressly specified, all ranges or ratios disclosed herein will be understood to include any and all sub-ranges or sub-ratios contained therein. For example, a range or ratio of 1 to 30 as claimed should be considered to include any sub-range or sub-ratio between the minimum value of 1 and the maximum value of 30, including endpoints and any sub-range or sub-ratio consisting of integers or decimals.

[0024] The following non-limiting examples can make those skilled in the art more fully understand the present application, but do not limit the present application in any way. The following is only an exemplary description of the scope claimed by the present application, and those skilled in the art can make various changes and modifications to the present application based on the disclosed content, which should also belong to the scope claimed by the present application.

[0025] The present application is further described below in the form of specific examples. The various chemical reagents used in the examples of the present application are obtained by conventional commercial routes unless otherwise specified. If not otherwise specified, the content described below is the mass content. If not otherwise specified, it is understood to be carried out at room temperature.

[0026] In the following examples, some reagents are as follows in Table 1: Table 1

[0027] The formulations and component weights of Examples 1-5 below are shown in Table 2 as follows: Table 2

[0028] Example 1 The preparation was carried out according to the formula amount of Example 1 in Table 2 above in the following steps: S1, water, tannic acid, cardanol sulfonic acid, aralkyl phenol and dimethyl phenol were added to the reaction kettle, heated to 45℃ and continuously stirred for 30min; S2, the reaction kettle was cooled to 30℃, and formaldehyde, bio-based aldehyde and propylene aldehyde were slowly added dropwise into the reaction kettle, and continuously stirred, the reaction temperature was controlled at 60℃ during the dropwise addition, and after the dropwise addition was completed, the stirring was continued for 60min; S3, the reaction kettle was cooled to 50℃, and concentrated sulfuric acid and acetic acid were slowly added dropwise into the reaction kettle, and continuously stirred, the reaction temperature was controlled at 60℃ during the dropwise addition; after the dropwise addition was completed, the temperature was raised to 90℃, and the temperature was kept for 3 hours; S4, sodium hydroxide was prepared into a 10% mass fraction aqueous solution, the reaction kettle was cooled to 30℃, and the prepared sodium hydroxide aqueous solution and ammonia water were slowly added dropwise into the reaction kettle, and stirred for 30min; S5, the reaction kettle was cooled to room temperature, and the acidic fixing agent was obtained.

[0029] Example 2 The preparation was carried out according to the formula amount of Example 2 in Table 2 above in the following steps: S1, water, tannic acid, cardanol sulfonic acid, aralkyl phenol and dimethyl phenol were added to the reaction kettle, heated to 40℃ and continuously stirred for 40min; S2, the reaction kettle was cooled to 20℃, and formaldehyde, bio-based aldehyde and propylene aldehyde were slowly added dropwise into the reaction kettle, and continuously stirred, the reaction temperature was controlled at 50℃ during the dropwise addition, and after the dropwise addition was completed, the stirring was continued for 90min; S3, the reaction kettle was cooled to 40℃, and concentrated sulfuric acid and acetic acid were slowly added dropwise into the reaction kettle, and continuously stirred, the reaction temperature was controlled at 50℃ during the dropwise addition; after the dropwise addition was completed, the temperature was raised to 80℃, and the temperature was kept for 4 hours; S4, sodium hydroxide was prepared into a 25% mass fraction aqueous solution, the reaction kettle was cooled to 25℃, and the prepared sodium hydroxide aqueous solution and ammonia water were slowly added dropwise into the reaction kettle, and stirred for 40min; S5, the reaction kettle was cooled to room temperature, and the acidic fixing agent was obtained.

[0030] Example 3 The preparation was carried out according to the formula amount of Example 3 in Table 2 above in the following steps: S1, water, tannic acid, cardanol sulfonic acid, aralkyl phenol and dimethyl phenol were added to the reaction kettle, heated to 50℃ and continuously stirred for 20min; S2, cool the reaction kettle to 40℃, slowly drop formaldehyde, bio-based aldehyde and propyl aldehyde into the reaction kettle, and continuously stir, control the reaction temperature at 70℃ during the dropping process, and continuously stir for 45 min after the dropping process is completed; S3, cool the reaction kettle to 60℃, slowly drop concentrated sulfuric acid and acetic acid into the reaction kettle, and continuously stir, control the reaction temperature at 70℃ during the dropping process; after the dropping process is completed, heat to 100℃, and keep for 1 hour; S4, configure sodium hydroxide into a water solution with a mass fraction of 50%, cool the reaction kettle to 35℃, slowly drop the prepared sodium hydroxide water solution and ammonia water into the reaction kettle, and stir for 20 min; S5, cool the reaction kettle to room temperature, and the acidic color fixing agent can be obtained.

[0031] Example 4 According to the formula amount of example 4 in table 2 above, the only difference is that the temperature of step S3 is different: S3, cool the reaction kettle to 50℃, slowly drop concentrated sulfuric acid and acetic acid into the reaction kettle, and continuously stir, control the reaction temperature at 70℃ during the dropping process; after the dropping process is completed, heat to 90℃, and keep for 3 hours.

[0032] The rest is the same as example 1.

[0033] Example 5 According to the formula amount of example 5 in table 2 above, the only difference is that the temperature of step S3 is different: S3, cool the reaction kettle to 50℃, slowly drop concentrated sulfuric acid and acetic acid into the reaction kettle, and continuously stir, control the reaction temperature at 50℃ during the dropping process; after the dropping process is completed, heat to 90℃, and keep for 3 hours.

[0034] The rest is the same as example 1.

[0035] Comparative example 1 Compared with example 1, the only difference is that dimethyl phenol is replaced by trimethyl phenol. The rest is the same as example 1.

[0036] Comparative example 2 Compared with example 1, the only difference is that 6g of glutaraldehyde is replaced by 3g of glutaraldehyde and 3g of furfural (cas number 98-01-1). The rest is the same as example 1.

[0037] Comparative example 3 Compared with example 1, the only difference is that the amount of tannic acid and cashew phenol sulfonic acid is different: tannic acid is 5g, and cashew phenol sulfonic acid is 25g. The rest is the same as example 1.

[0038] Comparative example 4 The difference compared with Example 1 is that the reaction temperature is controlled at 40℃ during the dropwise addition in step S2: S2, cool the reaction kettle to 30℃, slowly drop formaldehyde, bio-based aldehyde and acrolein into the reaction kettle, and continuously stir, control the reaction temperature at 40℃ during the dropwise addition, and continuously stir for 60 min after the dropwise addition is completed.

[0039] The rest is the same as Example 1.

[0040] Comparative Example 5 The difference compared with Example 1 is that the reaction temperature is controlled at 85℃ during the dropwise addition in step S3: S3, cool the reaction kettle to 50℃, slowly drop concentrated sulfuric acid and acetic acid into the reaction kettle, and continuously stir, control the reaction temperature at 85℃ during the dropwise addition; after the dropwise addition is completed, heat to 90℃ and keep for 3 hours.

[0041] The rest is the same as Example 1.

[0042] Effect Example 1 According to the test method of USA EPA 3550 2007, the bisphenol and phenol content tests of the samples of Examples 1-5, the samples of Comparative Examples 1-5 and the commercially available fixing agent samples are carried out, and the results are shown in Table 3.

[0043] Table 3

[0044] As can be seen from Table 3, the environmentally friendly acidic fixing agent does not contain bisphenol A, B, S, F, AF and phenol, and can meet the environmental protection requirements.

[0045] Effect Example 2 At 80℃, with a bath ratio of 1:10, the samples of Examples 1-5, the samples of Comparative Examples 1-5 and the commercially available fixing agent are respectively fixed on the fabrics dyed with 1%, 2% and 4% (o.w.f) acidic LD black for 20 min, then the fabrics are rinsed with cold water, and then dehydrated and dried, and the fixed fabrics are tested for washing, perspiration and sea water fastness.

[0046] (1) Washing fastness test The test is carried out according to AATCC 61-2A method, AATCC rating gray sample card (AATCC-28360C) is used for rating, and the washing fastness test results of the fabrics treated with different fixing agents are shown in Table 4.

[0047] Table 4

[0048] As can be seen from Table 4, the samples of Examples 1-5 have excellent water washing fastness improvement effect, which is obviously better than Comparative Examples 1-5, market eco-friendly sample, market non-eco-friendly sample one, and close to market non-eco-friendly sample two.

[0049] (2) Sweat (alkali) fastness test The test was carried out according to ISO 105 E4, and the rating was carried out using AATCC rating staining gray sample card (AATCC-28360C). The sweat (alkali) fastness test results of the fabrics treated with different fixing agents are shown in Table 5.

[0050] Table 5

[0051] As can be seen from Table 5, the samples of Examples 1-5 have excellent sweat fastness improvement effect, which is obviously better than Comparative Examples 1-5, market eco-friendly sample, market non-eco-friendly sample one, and close to market non-eco-friendly sample two.

[0052] (3) Sea water fastness test: The test was carried out according to ISO 105 E02 method, and the rating was carried out using AATCC rating staining gray sample card (AATCC-28360C). The sea water fastness test results of the fabrics treated with different fixing agents are shown in Table 6.

[0053] Table 6

[0054] As can be seen from Table 6, the samples of Examples 1-5 have excellent sea water fastness improvement effect, which is obviously better than Comparative Examples 1-5, market eco-friendly sample, market non-eco-friendly sample one, and close to market non-eco-friendly sample two.

[0055] Example 3: Fixing color change test At 80°C, with a bath ratio of 1:10, the fabrics dyed with 1%, 2% and 4% (o.w.f) acid AFN dyes were fixed for 20 min using the samples of Examples 1-5, the samples of Comparative Examples 1-5 and commercially available fixing agents respectively, then the fabrics were rinsed with cold water and dried by dehydration, and the fixing color change of the fixed fabrics was tested. The color change test results (total color difference ΔE) of the fabrics treated with different acid fixing agents are shown in Table 7.

[0056] Table 7

[0057] As can be seen from Table 7, on blue nylon fabric, the eco-friendly acid fixing agent of the present application has no color change, and the fixing color change is obviously lighter than Comparative Examples 1-5, market eco-friendly sample, market non-eco-friendly sample one, and close to market non-eco-friendly sample two.

[0058] Effect Example 4: Anionic-cationic conflict risk test X g / L of the samples of Examples 1-5, Comparative Examples 1-5, and commercially available fixing agents were mixed with Y g / L of a cationic leveling agent, and the stability of the mixed solution was observed. The results of the anionic-cationic conflict risk test (appearance of working solution) of different fixing agents are shown in Table 8.

[0059] Table 8

[0060] As can be seen from Table 8, the anionic-cationic conflict of the environmentally friendly acid fixing agent of the present application is significantly less than that of Comparative Examples 1-5, the market environmentally friendly sample, the market non-environmentally friendly sample 1, and the market non-environmentally friendly sample 2.

[0061] Effect Example 5: White base anti-staining effect test At 80°C, white nylon cloth was treated with 1%, 2%, and 4% (o.w.f) of acid LD black dye in a bath ratio of 1:10 for 10 min using the amount of the samples of Examples 1-5, Comparative Examples 1-5, and commercially available fixing agents, respectively, and then rinsed with cold water, dehydrated and dried. The K / S value of the fixed fabric was tested. The K / S test results of the fabric treated with different acid fixing agents are shown in Table 9.

[0062] Table 9

[0063] As can be seen from Table 9, the samples of Examples 1-5 have excellent white base anti-staining effect, which is significantly better than that of Comparative Examples 1-5, the market environmentally friendly sample, and the market non-environmentally friendly sample 1.

[0064] According to the results of the above effect evaluation, the environmentally friendly acid fixing agent of the present application does not contain bisphenol A, B, S, F, AF, and phenol, and can meet the environmental protection requirements. In the washing fastness test, the perspiration (alkali) fastness test, and the seawater resistance test, the samples of Examples 1-5 are between 2-4 levels, while Comparative Examples 1-5, the market environmentally friendly sample, and the market non-environmentally friendly sample 1 are mostly between 1-3 levels. In the color change test, the samples of Examples 1-5 are between 0.48-0.64, while Comparative Examples 1-5, the market environmentally friendly sample, and the market non-environmentally friendly sample 1 are between 0.62-2.85. In the anionic-cationic conflict risk test, the samples of Examples 1-5 all show stability, while Comparative Examples 1-5, the market environmentally friendly sample, the market non-environmentally friendly sample 1, and the market non-environmentally friendly sample 2 all show instability. In the white base anti-staining effect test, the samples of Examples 1-5 are between 0.59-1.71, while Comparative Examples 1-5, the market environmentally friendly sample, and the market non-environmentally friendly sample 1 are between 1.33-8.37.

[0065] Finally, it should be noted that the above is only to illustrate the technical solutions of the present application, and is not a limitation on the scope of protection of the present application, and simple modifications or equivalent replacements of the technical solutions of the present application by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. An acidic fixing agent free from phenol and bisphenol, characterized by comprising: The components include the following components by weight: water 25-55 parts, tannic acid 10-35 parts, cashew phenol sulfonic acid 1-20 parts, aralkyl phenol 1-15 parts, dimethyl phenol 1-5 parts, formaldehyde 1-5 parts, bio-based aldehyde 1-10 parts, propylene aldehyde 1-10 parts, concentrated sulfuric acid 1-10 parts, acetic acid 1-5 parts, sodium hydroxide 1-10 parts and ammonia 1-5 parts.

2. The acid fixing agent according to claim 1, characterized by The components include the following components by weight: water 30-50 parts, tannic acid 15-30 parts, cashew phenol sulfonic acid 5-15 parts, aralkyl phenol 3-13 parts, dimethyl phenol 2-4 parts, formaldehyde 1-2 parts, bio-based aldehyde 2-8 parts, propylene aldehyde 1-5 parts, concentrated sulfuric acid 1-5 parts, acetic acid 1-2 parts, sodium hydroxide 1-5 parts and ammonia 1-3 parts.

3. The acid fixing agent according to claim 2, characterized by The components include the following components by weight: water 40 parts, tannic acid 20 parts, cashew phenol sulfonic acid 10 parts, aralkyl phenol 8 parts, dimethyl phenol 3 parts, formaldehyde 1 part, bio-based aldehyde 6 parts, propylene aldehyde 3 parts, concentrated sulfuric acid 3 parts, acetic acid 1 part, sodium hydroxide 3 parts and ammonia 2 parts.

4. The acid fixing agent according to claim 1, wherein The aralkyl phenol is selected from one or more of nonyl phenol polyoxyethylene ether, octyl phenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether.

5. The acidic fixing agent according to claim 1, wherein The bio-based aldehyde is selected from one or more of glutaraldehyde, hydroxymethyl furfural, glycerol aldehyde.

6. A process for the preparation of the acidic fixing agent according to any one of claims 1 to 5, characterized in that, The steps include: S1, by weight, water, tannic acid, cashew phenol sulfonic acid, aralkyl phenol and dimethyl phenol are mixed, heated and stirred to obtain a mixed solution; S2, the mixed solution obtained in step S1 is cooled, formaldehyde, bio-based aldehyde and propylene aldehyde are added dropwise, and stirring is continuously carried out, the reaction temperature is controlled, after the dropwise addition is completed, stirring is continued; S3, cooling, dropwise addition of concentrated sulfuric acid and acetic acid, and continuous stirring, control the reaction temperature; after the dropwise addition is completed, the temperature is raised and then kept, to obtain a reaction liquid; S4, the reaction liquid obtained in step S3 is cooled, and an aqueous solution of sodium hydroxide and ammonia are added dropwise, and stirring is continued; S5, cooled to room temperature, to obtain an acidic fixing agent.

7. The production method according to claim 6, wherein In step S1, the heating is specifically raised to 40-50℃, and the stirring time is 20-40min; in step S2, the cooling is specifically cooled to 20-40℃; in step S2, the control of the reaction temperature is specifically: the reaction temperature is controlled at 50-70℃, and the stirring time is 45-90min.

8. The preparation method according to claim 6, characterized in that, In step S3, the cooling is specifically: cooled to 40-60℃, and the control of the reaction temperature is specifically: the reaction temperature is controlled at 50-70℃; in step S3, the temperature is raised and then kept for 1-4h after the temperature is raised to 80-100℃; In step S4, the cooling is specifically cooled to 25-35℃, and the continuous stirring time is 20-40min.

9. The preparation method according to claim 6, characterized in that, In step S4, the mass fraction of the aqueous solution of sodium hydroxide is 10-50%.

10. The acidic fixing agent according to any one of claims 1-5 or prepared by the preparation method according to any one of claims 6-9 is applied in dyeing of polyamide.

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