A diphenol-free environment-friendly acid fixing agent and a preparation method thereof

Abstract

The application discloses an environment-friendly acid fixing agent without bisphenol and a preparation method thereof, and comprises the following steps: 1) screening and optimizing raw material combination, taking non-limiting phenolic compounds as polycondensation reaction monomers, including high-purity p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxyacetophenone, p-hydroxypropiophenone and sodium p-hydroxybenzenesulfonate, preparing formaldehyde aqueous solution, alkali catalyst and acid catalyst; 2) adding the non-limiting phenolic compounds, catalyst, water or solvent in a set formula amount into a reaction kettle, stirring and heating to 70-80 DEG C, then slowly adding a set amount of formaldehyde solution, slowly heating to 90-101 DEG C and keeping the temperature, and reacting; and 3) adjusting sulfonation degree and post-treatment. The fixing performance of the application can reach the level of conventional acid fixing agents.

Description

Technical Field

[0001] This invention belongs to the field of textile color-fixing agents, specifically relating to a bisphenol-free, environmentally friendly acidic color-fixing agent and its preparation method for color-fixing treatment after dyeing nylon / nylon-spandex fabrics. Background Technology

[0002] Nylon is the second largest synthetic fiber after polyester, with large production volume and wide application, especially irreplaceable in applications requiring abrasion resistance, elasticity, and lightweight properties. China is the world's largest nylon producer (accounting for approximately 60% of global production), holding a significant industrial position. Nylon fabrics are generally dyed with acid dyes, but acid dyes for nylon have poor wet treatment fastness (including water fastness, soaping fastness, and perspiration fastness), usually requiring the use of acid fixing agents for color fixation. Currently, most common acid fixing agents on the market are aromatic sulfonic acid condensation polymers, belonging to synthetic tannin derivatives, produced by the condensation reaction of bisphenol S (4,4'-dihydroxydiphenyl sulfone) or phenol with formaldehyde. These raw materials inevitably leave residual bisphenol S or phenol in the acid fixing agent product, generating bisphenol F during the reaction. Bisphenol compounds (including bisphenol A, B, F, S, AF, etc.) have been proven to be endocrine disruptors, causing endocrine disorders and reproductive toxicity in humans, and also polluting and damaging the ecological environment. In recent years, global environmental regulations for textiles have become increasingly stringent regarding bisphenol A (BPA), with many international textile and apparel brands requiring total BPA content in fabrics to be below 0.1 ppm. To meet the demands of downstream customers, domestic dyeing and printing companies have imposed stringent requirements on their fixing agent suppliers, demanding that the total BPA content in the fixing agent solution be below 1 ppm or below 0.1 ppm. The 2024 edition of the "Technical Guidelines for Green and Low-Carbon Development in the Dyeing and Printing Industry" also explicitly lists "phenol-free nylon fixing technology" as a promoted technology, making the development and use of BPA-free, environmentally friendly acidic fixing agents an inevitable trend in the industry.

[0003] Patent publication number CN117468254B ​​discloses a novel bisphenol S-free acidic fixing agent and its preparation method, mainly prepared by reacting phenol, acrylic acid, sodium sulfite, acetic acid, and other components under concentrated sulfuric acid catalysis. The reaction mechanism for preparing this fixing agent is unclear, and the product structure does not meet the requirements of the classic acidic fixing agent fixing principle, making its fixing effect questionable. Although it emphasizes being bisphenol S-free, it still uses phenol in its formulation, significantly reducing its environmental friendliness. CN118756511A discloses a method for preparing an environmentally friendly acidic fixing agent that does not contain bisphenol S, bisphenol F, or phenol. This fixing agent is prepared by mixing a high-molecular-weight aromatic sulfonic acid condensate with conventional additives. This patent selects a high-molecular-weight aromatic sulfonic acid condensate as the core component of the fixing agent, but its specific structure and composition are unknown. Conventional acidic fixing agents containing bisphenol are themselves a type of high-molecular-weight aromatic sulfonic acid condensate, so the environmental friendliness of this patented acidic fixing agent is questionable. Patent application publication number CN120905985A discloses an "acidic fixing agent free of phenol and bisphenols, its preparation method and application," which involves a phenolic condensation reaction between phenols such as tannic acid, cashew phenol sulfonic acid, arylalkylphenols and xylenol and formaldehyde, followed by sulfonation with concentrated sulfuric acid and pH adjustment to obtain the product. This acidic fixing agent involves the condensation reactions of multiple phenols and aldehydes during synthesis, resulting in a complex composition and difficult-to-control reaction process, hindering large-scale production. Furthermore, the xylenol used is restricted by numerous environmental regulations. CN119219911A discloses "a bisphenol-free acidic fixing agent based on plant extracts and its preparation method." While this fixing agent uses natural plant polyphenols as raw materials, it suffers from limitations in fixing performance, exhibiting poor fastness to water immersion and soap washing, and the plant polyphenols inevitably cause severe color changes during fixing.

[0004] In summary, balancing the product's color-fixing effect (high color fastness and minimal color change), environmental friendliness (no restricted phenolic compounds), and universal applicability to various processes remains a major challenge for environmentally friendly acidic color-fixing agents. Developing a novel environmentally friendly acidic color-fixing agent that avoids the use of restricted phenolic raw materials at the source and completely solves the problem of excessive bisphenol levels through a novel molecular structure design has become an urgent and important technical issue in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a bisphenol-free, environmentally friendly acidic fixing agent and its preparation method, so as to overcome the shortcomings of the prior art. Starting from first principles, namely the structure-activity relationship and fixing mechanism of acidic fixing agents, this invention designs and develops a bisphenol-free, environmentally friendly acidic fixing agent based on non-restrictive phenolic compounds as raw materials. This avoids the problems of bisphenol F and bisphenol S brought about by raw materials such as phenol and bisphenol S from the source. The obtained product meets stringent environmental regulations (the content of bisphenol S, bisphenol F, and other bisphenol compounds in the raw solution is <0.1 ppm), while achieving fixing performance at the level of conventional acidic fixing agents.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: a bisphenol-free environmentally friendly acidic color-fixing agent, which first selects suitable non-restricted phenolic compounds as monomers for polycondensation reaction, uses sodium p-hydroxybenzenesulfonate as a monomer providing sulfonic acid groups, and carries out a co-condensation reaction with formaldehyde under alkaline or acidic catalytic conditions to obtain a water-soluble polycondensate with suitable degree of polymerization and sulfonation. The general structural formula of the water-soluble polycondensate is as follows. Where n is 20~50, and X and Y are one of the electron-withdrawing groups such as aldehyde, carboxyl, and ketone groups. The electron-withdrawing groups weaken the oxidizing property of the phenolic hydroxyl group, thereby improving the color change of the solid color. The preparation method of the bisphenol-free environmentally friendly acidic color-fixing agent includes the following steps: (1) Screening and optimization of raw material combination: Based on the structure-activity relationship and fixing mechanism of acidic fixing agents, the basic principle for selecting raw materials is that their molecular structure must have a high proportion of phenolic hydroxyl groups but not be restricted by environmental regulations, and can undergo condensation reaction with formaldehyde. Non-restricted phenolic compounds are used as monomers for condensation reaction, including one or more of high-purity p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxyacetophenone, p-hydroxyphenylacetone, and sodium p-hydroxybenzenesulfonate (all with a content ≥99.5%); and formaldehyde aqueous solution (37% content), alkaline catalyst and acid catalyst are prepared. (2) Polycondensation reaction: Add the non-restricted phenolic compound, catalyst, water or solvent of the specified formula to the reaction vessel, stir and heat to 70~80℃, then slowly add the specified amount of formaldehyde solution, and control the adding time to 0.5~1 hour; after the addition is completed, slowly heat to 90~101℃ and keep the reaction at this temperature for 6~10 hours. (3) Control of reaction degree: The degree of condensation reaction between the non-restrictive phenolic compound and formaldehyde is adjusted by controlling the reaction temperature and time, so as to obtain a condensation polymer with the target degree of polymerization (molecular weight); (4) Sulfonation degree adjustment: By adjusting the addition ratio of sodium p-hydroxybenzenesulfonate, the sulfonation degree of the final product can be controlled, thereby adjusting its water solubility and affinity for nylon fibers; (5) Post-processing: After the reaction is completed, the reaction system is cooled to below 40°C, the pH value is adjusted to 6.0~8.0 with acid or alkali, water is added to adjust the solid content, and the product is obtained after filtration.

[0007] Preferably, in step (1), the non-restricted phenolic compounds are combinations of high-purity (p-hydroxybenzoic acid + p-hydroxybenzaldehyde), (p-hydroxybenzoic acid + p-hydroxyacetophenone), and (p-hydroxybenzoic acid + p-hydroxyacetophenone) with sodium p-hydroxybenzenesulfonate.

[0008] Further, in step (2), the ratio of the total number of moles of the non-restrictive phenolic compounds to the number of moles of formaldehyde is 1:(0.8~1.5).

[0009] Further, in step (2), the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, and sodium carbonate; the amount of catalyst added is 1 to 10% of the total mass of the non-limiting phenolic compounds.

[0010] Further, in step (2), the solvent is one or a mixture of two of acetic anhydride, acetic acid and diethylene glycol.

[0011] Further, in step (2), the acid catalyst includes one of sulfuric acid, hydrochloric acid, and oxalic acid; the amount of catalyst added is 1 to 10% of the total mass of the non-limiting phenolic compounds.

[0012] Furthermore, in step (5), the solid content of the final product is adjusted to 25-40%.

[0013] On the other hand, the present invention provides a bisphenol-free environmentally friendly acidic color-fixing agent prepared by the above-described method. This color-fixing agent is an aromatic sulfonic acid polymer formed by combining high-purity (p-hydroxybenzoic acid + p-hydroxybenzaldehyde), (p-hydroxybenzoic acid + p-hydroxyacetophenone), and (p-hydroxybenzoic acid + p-hydroxyacetone) with sodium p-hydroxybenzenesulfonate, and then reacting them with formaldehyde via a condensation reaction. Its molecular structure does not contain any bisphenol-like structural units such as bisphenol S and bisphenol F, and the total bisphenol content of the product stock solution is less than 0.1 ppm.

[0014] The above technical solution has the following beneficial effects: (1) Avoiding bisphenol problems and meeting stringent environmental protection requirements: This invention innovatively selects high-purity p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxyacetophenone, p-hydroxyphenylacetone, and sodium p-hydroxybenzenesulfonate as monomers for the polycondensation reaction. These monomer raw materials contain phenolic hydroxyl groups in their molecular structure, which can undergo condensation reactions with formaldehyde. However, they are not subject to international environmental regulations, and no bisphenol S and bisphenol F or other bisphenol-related prohibited substances are generated during the reaction. This avoids the problem of excessive bisphenol S or bisphenol F in traditional acidic color fixing agents from the source. The bisphenol content of the product can be controlled at <0.1 ppm, which fully meets the environmental protection requirements of Blue Label, ZDHC, OEKO-TEX Standard 100, etc.

[0015] (2) Excellent color-fixing performance: By controlling the degree of polycondensation reaction (molecular weight) and the degree of sulfonation, the performance of the product can be precisely controlled. The appropriate molecular weight allows it to form a complete film coating on the surface of nylon fibers, while the sulfonic acid groups provide good water solubility and ionic bonding ability with fibers, which significantly improves the color fastness of acid dyes on nylon and other fabrics, such as wash fastness, water fastness, and perspiration and alkali fastness, and the color change after color fixation is also very small.

[0016] (3) Mature process and easy to industrialize: The preparation method described in this invention is based on a mature polycondensation reaction process. The raw materials are readily available, the operation is simple, and the equipment requirements are low, making it very suitable for large-scale industrial production. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to examples. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0018] The preparation method of bisphenol-free environmentally friendly acidic fixing agent is as follows: In a four-necked flask equipped with a reflux condenser, stirrer, and thermometer, 30 parts of p-hydroxybenzoic acid, 30 parts of p-hydroxybenzaldehyde, and 40 parts of sodium p-hydroxybenzenesulfonate were added, followed by 100 parts of deionized water and 6 parts of sodium hydroxide (as a catalyst). Stirring was started, and the temperature was raised to 70°C. After the temperature stabilized, 55 parts of a 37% formaldehyde aqueous solution were slowly added dropwise over a period of 1 hour. After the addition was complete, the temperature was raised to 97-99°C and maintained for 8 hours. After the reaction, the system was cooled to 40°C, and the pH was adjusted to approximately 8.0 with a small amount of glacial acetic acid. Finally, deionized water was added to adjust the solid content of the product to approximately 30%, yielding a reddish-brown transparent liquid, which is the bisphenol-free environmentally friendly acidic fixing agent. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the total bisphenol content of the product was undetectable (<0.1 ppm). Example 2

[0019] The preparation method of bisphenol-free environmentally friendly acidic fixing agent is as follows: In a four-necked flask equipped with a reflux condenser, stirrer, and thermometer, 30 parts of p-hydroxybenzoic acid, 33 parts of p-hydroxyacetophenone, and 40 parts of sodium p-hydroxybenzenesulfonate were added, followed by 100 parts of deionized water and 5.5 parts of sodium hydroxide. Stirring was started, and the temperature was raised to 70°C. After the temperature stabilized, 55 parts of a 37% formaldehyde aqueous solution were slowly added dropwise over a period of 1 hour. After the addition was complete, the temperature was raised to 95-97°C and maintained for 8 hours. After the reaction, the system was cooled to 40°C, and the pH was adjusted to approximately 8.0 with a small amount of glacial acetic acid. Finally, deionized water was added to adjust the solid content of the product to approximately 30%, yielding a yellowish-brown transparent liquid, which is the bisphenol-free environmentally friendly acidic fixing agent. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the total bisphenol content of the product was undetectable (<0.1 ppm). Example 3

[0020] The preparation method of bisphenol-free environmentally friendly acidic fixing agent is as follows: In a four-necked flask equipped with a reflux condenser, stirrer, and thermometer, add 30 parts of p-hydroxybenzoic acid, 36 parts of p-hydroxyacetone, and 40 parts of sodium p-hydroxybenzenesulfonate, followed by 100 parts of deionized water and 5 parts of sodium hydroxide. Start stirring and heat to 70°C. After the temperature stabilizes, slowly add 55 parts of a 37% formaldehyde aqueous solution dropwise over a period of 1 hour. After the addition is complete, heat to 94-96°C and maintain the temperature for 8 hours. After the reaction, cool the system to 40°C and adjust the pH to approximately 8.0 with a small amount of glacial acetic acid. Finally, add deionized water to adjust the solid content of the product to approximately 30%, yielding a yellow transparent liquid, which is the bisphenol-free environmentally friendly acidic fixing agent. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the total bisphenol content of the product was undetectable (<0.1 ppm). Example 4

[0021] The preparation method of bisphenol-free environmentally friendly acidic fixing agent is as follows: In a four-necked flask equipped with a reflux condenser, stirrer, and thermometer, 30 parts of p-hydroxybenzoic acid, 30 parts of p-hydroxybenzaldehyde, and 40 parts of sodium p-hydroxybenzenesulfonate were added, followed by 100 parts of acetic anhydride and 6 parts of oxalic acid (as catalysts). Stirring was started, and the temperature was raised to 80°C. After the temperature stabilized, 40 parts of a 37% formaldehyde aqueous solution were slowly added dropwise over a period of 1 hour. After the addition was complete, the temperature was raised to 90-92°C and maintained for 6 hours. After the reaction was complete, the system was cooled to 40°C, and the pH was adjusted to approximately 5.0 with a small amount of sodium hydroxide. Finally, deionized water was added to adjust the solid content of the product to approximately 30%, yielding a yellow transparent liquid, which is the bisphenol-free environmentally friendly acidic fixing agent. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the total bisphenol content of the product was undetectable (<0.1 ppm).

[0022] Performance testing methods: Bath ratio 1:10, 80 ℃×20 min, wash with water, dehydrate, dry at 100 ℃, test water fastness (bath ratio 1:50, Tide laundry detergent 2 g / L, soak in 80 ℃ water at room temperature for 5 min, compare color fading), wash fastness (GB / T 3921 C-2008 method), perspiration fastness (GB / T 3922-2013 method).

[0023] The performance test results of the bisphenol-free environmentally friendly acidic fixing agent prepared by the above method are as follows: The environmentally friendly acidic color-fixing agent prepared in the embodiments of the present invention was compared with a commercially available conventional sulfonated phenolic resin type color-fixing agent. The water immersion fastness of each embodiment is shown in Table 1, the soap washing fastness of Example 1 is shown in Table 2, and the perspiration and alkali fastness of Example 1 is shown in Table 3.

[0024] Table 1. Results of water fastness test of environmentally friendly acidic color-fixing agent in the examples.

[0025] Table 2 Results of color fastness test for Example 1

[0026] Table 3 Results of color fastness test for perspiration and alkali resistance in Example 1

[0027] As shown in Tables 1, 2, and 3, the test results of Examples 1-3 provided by this invention exhibit excellent water fastness, while the fastness of Example 4, which is acid-catalyzed, is somewhat worse. Furthermore, Example 1 demonstrates excellent color fastness to perspiration and alkali, as well as excellent color fastness to soap washing, with water washing fastness grades of 4 or higher at high dosages. In conclusion, the bisphenol-free environmentally friendly acidic color-fixing agent provided by this invention achieves or surpasses the color fastness improvement effects of traditional acidic color-fixing agents.

[0028] The embodiments of the present invention have been described in detail above with reference to specific examples, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing a bisphenol-free, environmentally friendly acidic color-fixing agent, characterized in that: First, non-restricted phenolic compounds were screened as monomers for the polycondensation reaction. Sodium p-hydroxybenzenesulfonate was used as a monomer to provide sulfonic acid groups, and it was co-polymerized with formaldehyde under alkaline or acid-catalyzed conditions to obtain a water-soluble polycondensate with suitable degree of polymerization and sulfonation. The general structural formula of the water-soluble polycondensate is as follows. Where n is 20~50, and X and Y are one of the electron-withdrawing groups such as aldehyde, carboxyl, and ketone. The electron-withdrawing groups weaken the oxidizing property of the phenolic hydroxyl group, thereby improving the color change of the solid color. The preparation method of bisphenol-free environmentally friendly acidic fixing agent includes the following steps: (1) Screening and optimization of raw material combination: Based on the structure-activity relationship and fixing mechanism of acidic fixing agents, the selection principle of raw materials is determined to be that they have a high proportion of phenolic hydroxyl groups in their molecular structure but are not subject to environmental regulations and can undergo condensation reaction with formaldehyde. Non-restricted phenolic compounds are used as monomers for condensation reaction. The non-restricted phenolic compounds include high-purity p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxyacetophenone, p-hydroxyacetone, and sodium p-hydroxybenzenesulfonate. The content of the above non-restricted phenolic compounds is ≥99.5%. A 37% formaldehyde aqueous solution, an alkaline catalyst, and an acid catalyst are also prepared. (2) Polycondensation reaction: Add non-restrictive phenolic compounds, catalyst, water or solvent to the reactor, stir and heat to 70-80℃, then slowly add formaldehyde solution, which accounts for 1-1.2 times the total molar amount of non-restrictive phenolic compounds, controlling the addition time to 0.5-1 hour; after the addition is complete, slowly heat to 90-101℃ and maintain the temperature for 6-10 hours. (3) Control of reaction degree: By controlling the reaction temperature and time, the degree of condensation reaction between non-restrictive phenolic compounds and formaldehyde is adjusted, thereby obtaining a condensation polymer with the target degree of polymerization (molecular weight). (4) Sulfonation degree adjustment: The sulfonation degree of the final product is controlled by adjusting the proportion of sodium p-hydroxybenzenesulfonate added, thereby adjusting its water solubility and affinity for nylon fibers. (5) Post-processing: After the reaction is completed, the reaction system is cooled to below 40°C, the pH value is adjusted to 6.0~8.0 with acid or alkali, water is added to adjust the solid content, and the product is obtained after filtration.

2. The preparation method according to claim 1, characterized in that: In step (1), the non-restricted phenolic compounds are high-purity combinations of (p-hydroxybenzoic acid + p-hydroxybenzaldehyde), (p-hydroxybenzoic acid + p-hydroxyacetophenone), and (p-hydroxybenzoic acid + p-hydroxyacetophenone) with sodium p-hydroxybenzenesulfonate.

3. The preparation method according to claim 1, characterized in that: In step (2), the ratio of the total number of moles of the non-restrictive phenolic compounds to the number of moles of formaldehyde is 1:(0.8~1.5).

4. The preparation method according to claim 1, characterized in that: In step (2), the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, and sodium carbonate; the amount of catalyst added is 1 to 10% of the total mass of the non-limiting phenolic compounds.

5. The preparation method according to claim 1, characterized in that: In step (2), the solvent is one or a mixture of two of acetic anhydride, acetic acid and diethylene glycol.

6. The preparation method according to claim 1, characterized in that: In step (2), the acid catalyst includes one of sulfuric acid, hydrochloric acid, and oxalic acid; the amount of catalyst added is 1 to 10% of the total mass of the non-limiting phenolic compounds.

7. The preparation method according to claim 1, characterized in that: In step (5), the solid content of the final product is adjusted to 25-40%.

8. A bisphenol-free, environmentally friendly acidic color-fixing agent, characterized in that: It is prepared according to the preparation method according to claim 1.

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