Azo dye for pet microfiber pu resin suede fabric and its preparation method and deep dyeing method

Abstract

The application belongs to the technical field of fabric dyeing, and provides an azo dye for PET superfine fiber PU resin suede fabric, a preparation method and a deep dyeing method of the azo dye. The method comprises the following steps: preparing a diazonium salt solution in a diazo component, dissolving a coupling component in water and hydrochloric acid or concentrated sulfuric acid, and then cooling in an ice bath to obtain a cooling liquid; adding the diazonium salt solution into the cooling liquid, keeping ice bath reaction after the addition is completed, removing the ice bath and continuing the reaction, and obtaining the azo dye. The azo dye has a molecular structure model, and the molecular ends both contain hydroxyl groups. In addition to intermolecular forces, more hydrogen bonds can be formed between the azo dye and PET superfine fiber and PU resin. The molecular structure of the azo dye is a monoazo disperse dye, the structure is relatively simple, the volume is small, more dye molecules can be accommodated in the amorphous region of the fiber, the adsorption saturation value is high, the bonding capacity is strong, and the azo dye has ideal deep dyeing, rubbing fastness and heat migration resistance.

Description

Technical Field

[0001] This invention relates to the field of fabric dyeing technology, and in particular to an azo dye for PET microfiber PU resin imitation suede fabric, its preparation method and deep dyeing method. Background Technology

[0002] PET microfiber PU resin imitation suede fabric is a composite material made of polyester (PET) microfiber layers impregnated with polyurethane (PU) resin. It possesses certain breathability and moisture permeability, and its appearance and performance are extremely similar to, or even surpass, natural leather. It is now widely used in high-end shoes, clothing, furniture, sports equipment, and automotive interiors. This type of imitation suede fabric is generally dyed with disperse dyes. Due to the large specific surface area of ​​its microfibers and the structural and performance differences between PET and PU, achieving deep dyeing of imitation suede fabric has become a significant technical challenge in the dyeing process of this type of product, attracting considerable attention from industry professionals.

[0003] PET microfiber has a large specific surface area and strong light reflection. Compared with conventional PET fiber, achieving a similar color depth requires adsorbing a larger amount of dye. Dye depth has become a technical challenge in dyeing PET microfiber. Different dye molecules have different molecular structures, resulting in different interaction forces, adsorption sites, and arrangements with fiber macromolecules. Therefore, the saturation adsorption capacity varies for dye molecules with different structures. To meet the technical requirements for dye depth, dye varieties with high saturation adsorption capacity and good enhancement properties should be selected.

[0004] Therefore, the research on a dye for PET microfiber PU resin imitation suede fabric and a dyeing method to improve dyeing depth, rubbing fastness and heat migration resistance is of great significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing an azo dye for PET microfiber PU resin imitation suede fabric, its preparation method, and its deep dyeing method.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an azo dye for PET microfiber PU resin imitation suede fabric, the structural formula of which is: ; Wherein, R is H, CH3 or OCH3, and X is H or CN; The structural formula for Ar is: , , or ; R1 and R2 can be H, Cl, Br, CN, or NO2 independently.

[0007] This invention also provides a method for preparing azo dyes for PET microfiber PU resin suede-like fabrics, comprising the following steps: 1) Preparation of diazonium salt solution: Method 1: Dissolve the diazonium component in water and concentrated hydrochloric acid, then cool to obtain a diazonium solution. Add an aqueous solution of sodium nitrite dropwise to the diazonium solution, continue the reaction, and then quench the sodium nitrite to obtain a diazonium salt solution. The diazo component is p-nitroaniline or o-chloro-p-nitroaniline; Method 2: Dissolve the diazonium component by adding it dropwise to concentrated sulfuric acid, then cool the solution. Add nitrite sulfuric acid dropwise to the cooling solution and continue the reaction to obtain a diazonium salt solution. The structural formula of the diazo component is: The structural formula of the diazonium salt is: ; The structural formula of Ar is: , , or ; R1 and R2 are independently Br, CN or NO2; 2) Preparation of azo dyes: The coupling component was dissolved in water and acid and then cooled in an ice bath to obtain a cooling solution. The diazonium salt solution was added dropwise to the cooling solution. After the addition was completed, the reaction was carried out in an ice bath. Then the ice bath was removed and the reaction continued to obtain the azo dye. The structural formula of the coupling component is: ; Where R is H, CH3 or OCH3, and X is H or CN.

[0008] Preferably, in step 1) of method one, the molar volume ratio of the diazo component, water and concentrated hydrochloric acid is 10 mmol: 10~15 mL: 4~6 mL; the molar ratio of sodium nitrite and diazo component is 10~11 mol: 10 mmol.

[0009] Preferably, in step 1) of method one, the dissolution temperature is 60~80℃, the cooling temperature is 0~5℃, the reaction continues at 0~5℃, the reaction continues for 1.5~2.5h, and the quenching agent is aminosulfonic acid.

[0010] Preferably, in step 1) of method two, the molar volume ratio of the diazo component to concentrated sulfuric acid is 10 mmol: 4~6 mL; the molar volume ratio of the diazo component to nitrosylsulfuric acid is 10 mmol: 2~2.5 mL.

[0011] As a preferred embodiment, in step 1) of method two, the cooling temperature is 0~5℃, the reaction temperature is 0~5℃, and the reaction time is 1.5~2.5h.

[0012] Preferably, the molar volume ratio of the coupling component, water, and acid in step 2) is 10~10.3mmol:40~60mL:2~5mL; the acid is hydrochloric acid or concentrated sulfuric acid. The ice bath cooling temperature is 0~10℃, the ice bath reaction time is 1.5~2.5h, and the reaction time is 2~4h after the ice bath is removed.

[0013] The present invention also provides a method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes, which involves mixing azo dyes, auxiliaries and water and then adding the mixture to the fabric for dyeing.

[0014] Preferably, the initial dyeing temperature is 65~75℃, the dyeing temperature is 125~135℃, the dyeing time is 30~60min, and the rate of heating to the dyeing temperature is 1~3℃ / min.

[0015] The beneficial effects of this invention include the following: 1) Based on the same chromogenic matrix, this invention synthesizes a series of disperse dyes containing different characteristic groups, which are applied to the dyeing of PET and PU fibers respectively. Through the testing of their adsorption isotherms and the analysis of adsorption parameter performance, the structure-activity relationship between characteristic groups and the dyeing performance of the two types of fibers is revealed. The structural model of the disperse dyes is optimized to be suitable for dyeing PET microfiber PU resin imitation suede fabric, obtaining relatively ideal dyeing depth, and having good rubbing fastness and heat migration resistance.

[0016] 2) The molecular structure model of the azo dye of the present invention contains hydroxyl groups (-OH) at the end of the molecules. In addition to generating intermolecular forces, it can also form a large number of hydrogen bonds with PET microfiber and PU resin. Its molecular structure is a monoazo disperse dye, which has a relatively simple structure and small volume, allowing the amorphous region of the fiber to accommodate a large number of dye molecules. It has a high adsorption saturation value and strong bonding ability, giving it ideal dyeing depth, rubbing fastness and heat migration resistance. Attached Figure Description

[0017] Figure 1 The infrared spectrum of the azo dye in Example 1; Figure 2 The infrared spectrum of the azo dye in Comparative Example 1 is shown. Figure 3 The infrared spectrum of the azo dye in Comparative Example 2 is shown. Figure 4The infrared spectrum of the azo dye in Comparative Example 3 is shown. Figure 5 The infrared spectrum of the azo dye in Comparative Example 4 is shown. Figure 6 The adsorption isotherms of the azo dyes used in Examples 1 and Comparative Examples 1-4 for dyeing PET fabrics are shown below. Wherein, D1 is Comparative Example 1, D2 is Comparative Example 2, D3 is Comparative Example 3, D4 is Comparative Example 4, and D5 is Example 1. Figure 7 The adsorption isotherms of azo dyes on PU fibers in Examples 1 and Comparative Examples 1-4 are shown below. Wherein, D1 is Comparative Example 1, D2 is Comparative Example 2, D3 is Comparative Example 3, D4 is Comparative Example 4, and D5 is Example 1. Figure 8 The azo dyes used in Examples 1 and Comparative Examples 1-4 are used to improve the dyeing performance of imitation suede fabric. D1 is Comparative Example 1, D2 is Comparative Example 2, D3 is Comparative Example 3, D4 is Comparative Example 4, and D5 is Example 1. Figure 9 The infrared spectrum of Disperse Orange A from Example 2; Figure 10 The infrared spectrum of Disperse Blue A in Example 3; Figure 11 The graph shows the performance improvement of hydroxyl-containing dyes on the dyeing of imitation suede fabric in Examples 2 and 3. Detailed Implementation

[0018] This invention provides an azo dye for PET microfiber PU resin imitation suede fabric, the structural formula of which is: ; Wherein, R is H, CH3 or OCH3, and X is H or CN; The structural formula for Ar is: , , or ; R1 and R2 can be H, Cl, Br, CN, or NO2 independently.

[0019] This invention also provides a method for preparing azo dyes for PET microfiber PU resin suede-like fabrics, comprising the following steps: 1) Preparation of diazonium salt solution: Method 1: Dissolve the diazonium component in water and concentrated hydrochloric acid, then cool to obtain a diazonium solution. Add an aqueous solution of sodium nitrite dropwise to the diazonium solution, continue the reaction, and then quench the sodium nitrite to obtain a diazonium salt solution. The diazo component is p-nitroaniline or o-chloro-p-nitroaniline; Method 2: Dissolve the diazonium component by adding it dropwise to concentrated sulfuric acid, then cool the solution. Add nitrite sulfuric acid dropwise to the cooling solution and continue the reaction to obtain a diazonium salt solution. The structural formula of the diazo component is: The structural formula of the diazonium salt is: ; The structural formula of Ar is: , , or ; R1 and R2 are independently Br, CN or NO2; 2) Preparation of azo dyes: The coupling component was dissolved in water and acid and then cooled in an ice bath to obtain a cooling solution. The diazonium salt solution was added dropwise to the cooling solution. After the addition was completed, the reaction was carried out in an ice bath. Then the ice bath was removed and the reaction continued to obtain the azo dye. The structural formula of the coupling component is: ; Where R is H, CH3 or OCH3, and X is H or CN.

[0020] In step 1) of this invention, the preferred molar volume ratio of the diazo component, water, and concentrated hydrochloric acid is 10 mmol: 10-15 mL: 4-6 mL, more preferably 10 mmol: 11-14 mL: 4.5-5.5 mL, and even more preferably 10 mmol: 12-13 mL: 5 mL; the preferred molar ratio of sodium nitrite to the diazo component is 10-11 mol: 10 mmol, more preferably 10.5 mol: 10 mmol.

[0021] In step 1) of this invention, the dissolution temperature is preferably 60~80℃, more preferably 65~75℃, and the cooling temperature is preferably 0~5℃; after the diazo component is dissolved, the temperature is lowered to 0~5℃, and the reaction continues for 1.5~2.5h, more preferably 2h; the reaction progress is preferably tracked by an amino reagent, and the quenching reagent is preferably aminosulfonic acid.

[0022] In step 1) of the present invention, the molar volume ratio of the diazo component to concentrated sulfuric acid is preferably 10 mmol: 4~6 mL, more preferably 10 mmol: 5 mL; the molar volume ratio of the diazo component to nitrosyl sulfuric acid is 10 mmol: 2~2.5 mL, more preferably 10 mmol: 2.2~2.3 mL.

[0023] In step 1) of the present invention, the cooling temperature is preferably 0~5℃, the reaction time is preferably 1.5~2.5h, and more preferably 2h; the reaction endpoint is preferably detected by the ice-water method.

[0024] In this invention, the preferred molar volume ratio of the coupling component, water, and acid in step 2) is 10~10.3mmol:40~60mL:2~5mL, more preferably 10.1~10.2mmol:45~55mL:3~4mL, and even more preferably 10.2mmol:50mL:3.5mL; the acid is hydrochloric acid or concentrated sulfuric acid. The preferred temperature for cooling in the ice bath is 0~10℃; the preferred time for maintaining the reaction in the ice bath is 1.5~2.5h, more preferably 2h; the preferred time for continuing the reaction after removing the ice bath is 2~4h, more preferably 3h.

[0025] The present invention also provides a method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes, which involves mixing azo dyes, auxiliaries and water and then adding the mixture to the fabric for dyeing.

[0026] In this invention, the initial dyeing temperature is preferably 65~75℃, more preferably 68~72℃, and even more preferably 70℃; the dyeing temperature is preferably 125~135℃, and even more preferably 130℃; the dyeing time is preferably 30~60min, more preferably 40~50min, and even more preferably 45min; the rate of heating to the dyeing temperature is preferably 1~3℃ / min, more preferably 1.5~2.5℃ / min, and even more preferably 2℃ / min.

[0027] In this invention, the owf of the azo dye is preferably 0.1-10%, more preferably 6-8%; the liquor ratio is preferably 5-50:1, more preferably 5-10:1.

[0028] In this invention, the additives preferably include a pH adjuster and a dispersant MF. The concentration of the dispersant MF is preferably 0.5~2 g / L, more preferably 1 g / L. The pH adjuster is preferably ammonium sulfate or acetic acid, which adjusts the pH value to 5~6. The concentration of ammonium sulfate is preferably 0.8~1.2 g / L, more preferably 1 g / L. The concentration of acetic acid is preferably 0.8~1.2 mL / L, more preferably 1 mL / L.

[0029] In this invention, after dyeing, the material is cooled, preferably to 75-85°C, more preferably to 80°C. After cooling, the PET fibers are sequentially subjected to reduction cleaning and water cleaning, while the PU fibers are subjected to water cleaning. The reagent for reduction cleaning preferably includes sodium hydrosulfite, caustic soda, and water, with the concentrations of sodium hydrosulfite and caustic soda preferably being 1.8-2.2 g / L, more preferably 2 g / L. The temperature for reduction cleaning is preferably 80-90°C, more preferably 82-88°C, and more preferably 84-85°C. The reduction cleaning time is preferably 12-17 min, more preferably 13-16 min, and more preferably 14-15 min. The liquor ratio is preferably 5-50:1, more preferably 5-10:1.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 Preparation of p-nitrodiazonium salt: 10 mmol of p-nitroaniline was added to a 50 mL three-necked flask, followed by 10 mL of water and 5 mL of concentrated hydrochloric acid. Stirring was started, and the mixture was heated in a water bath to 60 °C. After dissolution, the solution was cooled to 0–5 °C in an ice bath to obtain a p-nitroaniline solution. 10.5 mol of sodium nitrite was dissolved in 3 mL of water, and the sodium nitrite solution was slowly added dropwise to the p-nitroaniline solution. The reaction was continued at 0–5 °C for 2 h. The reaction progress was monitored using an amino reagent (p-dimethylaminobenzaldehyde). After the reaction was complete, excess sodium nitrite was quenched by adding aminosulfonic acid.

[0032] Preparation of azo dyes: In a 500 mL three-necked flask, add 60 mL of water, 4 mL of concentrated sulfuric acid, and 3 drops of fatty alcohol polyoxyethylene ether-9 (AEO-9). Start stirring, add 10 mmol of the coupling component, and stir at room temperature until dissolved. Cool the mixture to 0–10 °C in an ice bath. Slowly add the diazonium salt solution dropwise into the cooling solution, adding crushed ice to maintain the temperature at 0–10 °C during the addition process. The addition time is 30 min. After the addition is complete, maintain the reaction in an ice bath for 2 h, then remove the ice bath and continue the reaction for 4 h. Filter the solution and purify it using DMF-water recrystallization to obtain the azo dye.

[0033] The structural formula of p-nitrodiazonium salt is:

[0034] The structural formulas of the coupling component and the azo dye are as follows: , A is OH.

[0035] Comparative Example 1 The preparation of the p-nitrodiazonium salt is the same as in Example 1.

[0036] Preparation of the coupling component: 40 mL of dichloromethane was added to a 500 mL three-necked flask as solvent. Then, 0.2 g of 4-dimethylaminopyridine and 2 mL of triethylamine were added sequentially. After complete dissolution, 10 mmol of N-ethyl-N-hydroxyethylm-toluidine and 10.5 mmol of p-methylbenzoyl chloride were added sequentially. The reaction solution was ultrasonically vibrated (53 kHz) for 30 s at room temperature, and after standing for 30 min, a thin-layer chromatography (TLC) sample was applied to monitor the reaction progress. After the reaction was completed, the dichloromethane was evaporated to dryness at 40 °C to obtain the coupling component, which was directly used for the next step of preparing azo dyes.

[0037] The structural formulas of N-ethyl-N-hydroxyethyl m-toluidine and the coupling component are as follows: , .

[0038] In the preparation of azo dyes, 60 mL of water, 60 mL of anhydrous ethanol, 4 mL of concentrated sulfuric acid and 3 drops of AEO-9 were added to a 500 mL three-necked flask. The coupling component was different from that in Example 1, but the other conditions were the same as in Example 1.

[0039] The structural formula of azo dyes is: A is .

[0040] Comparative Example 2 The preparation of the p-nitrodiazonium salt is the same as in Example 1.

[0041] The structural formula of the coupling component is:

[0042] Preparation of the coupling component: 40 mL of dichloromethane was added to a 200 mL single-necked flask as solvent, followed by the sequential addition of 10 mmol N-ethyl-N-hydroxyethyl m-toluidine and 10.5 mmol p-toluene isocyanate. The reaction mixture was ultrasonically vibrated (53 kHz) for 30 s at room temperature, allowed to stand for 30 min, and then thin-layer chromatography was performed to monitor the reaction progress. After the reaction was complete, the dichloromethane was evaporated to dryness at 40 °C to obtain a white solid product with a yield of 98%.

[0043] In the preparation of azo dyes, 60 mL of water, 60 mL of anhydrous ethanol, 4 mL of concentrated sulfuric acid and 3 drops of AEO-9 were added to a 500 mL three-necked flask. The coupling component was different from that in Example 1, but the other conditions were the same as in Example 1.

[0044] The structural formula of azo dyes is: A is .

[0045] Comparative Example 3 The preparation of the p-nitrodiazonium salt is the same as in Example 1.

[0046] Preparation of the coupling component: 40 mL of dichloromethane was added to a 500 mL three-necked flask as solvent. Then, 0.2 g of 4-dimethylaminopyridine and 2 mL of triethylamine were added sequentially. After thorough dissolution and mixing, 10 mmol of N-ethyl-N-aminoethylm-toluidine and 10.5 mmol of p-methylbenzoyl chloride were added sequentially. The reaction solution was ultrasonically vibrated (53 kHz) for 30 s at room temperature, and after standing for 30 min, a thin-layer chromatography (TLC) sample was applied to monitor the reaction progress. After the reaction was completed, the dichloromethane was evaporated to dryness at 40 °C to obtain the coupling component, which was directly used in the next coupling reaction.

[0047] The structural formulas of N-ethyl-N-aminoethyl m-toluidine and the coupling component are as follows: , .

[0048] In the preparation of azo dyes, 60 mL of water, 60 mL of anhydrous ethanol, 4 mL of concentrated sulfuric acid and 3 drops of AEO-9 were added to a 500 mL three-necked flask. The coupling component was different from that in Example 1, but the other conditions were the same as in Example 1.

[0049] The structural formula of azo dyes is: A is .

[0050] Comparative Example 4 The preparation of the p-nitrodiazonium salt is the same as in Example 1.

[0051] Preparation of the coupling component: 40 mL of dichloromethane was added to a 200 mL single-necked flask as solvent, followed by the sequential addition of 10 mmol N-ethyl-N-aminoethylm-toluidine and 10.5 mmol p-toluene isocyanate. The reaction mixture was ultrasonically vibrated (53 kHz) for 30 s at room temperature, allowed to stand for 30 min, and then thin-layer chromatography was performed to monitor the reaction progress. After the reaction was complete, the dichloromethane was evaporated to dryness at 40 °C to obtain a white solid product with a yield of 98%.

[0052] The structural formula of the coupling component is: .

[0053] In the preparation of azo dyes, 60 mL of water, 60 mL of anhydrous ethanol, 4 mL of concentrated sulfuric acid and 3 drops of AEO-9 were added to a 500 mL three-necked flask. The coupling component was different from that in Example 1, but the other conditions were the same as in Example 1.

[0054] The structural formula of azo dyes is: A is .

[0055] The infrared spectra of the azo dyes in Example 1 and Comparative Examples 1-4 are shown below. Figures 1-5 As shown. By Figure 1 It can be seen that 3313cm -1 The peak is the stretching vibration peak of the hydroxyl group (OH), at 2971 cm⁻¹. -1 This is the stretching vibration peak of CH in the methylene group, at 1596 cm⁻¹. -1 This is the stretching vibration peak of the carbonyl group (C=O) in the ester group, at 1539 cm⁻¹. -1 The peak represents the stretching vibration of an azo group (N=N) or a benzene ring (C=C), at 1503 cm⁻¹. -1 The peak represents the asymmetric stretching vibration of NO2, at 1423 cm⁻¹. -1 The peak represents the OH bending (in-plane) vibration, at 1323 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1250 cm⁻¹. -1 The peak for CN stretching vibration is 1104 cm⁻¹. -1 This is the peak of the CO stretching vibration in the ester group. Figure 2 It can be known that 1714cm -1 This is the stretching vibration peak of the carbonyl group (C=O) in the ester group, at 1593 cm⁻¹. -1 This is a stretching vibration peak at 1508 cm⁻¹, representing either an azo group (N=N) or an inter-ring (C=C) stretching vibration. -1 The peak represents the asymmetric stretching vibration of NO2, at 1321 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1253 cm⁻¹. -1 The peak for CN stretching vibration is 1093 cm⁻¹. -1 This is the peak of the CO stretching vibration in the ester group. Figure 3 It can be known that 3315cm -1 This is the (NH) stretching vibration peak in carbamates, at 2969 cm⁻¹. -1 This is the stretching vibration peak of CH in the methylene group, at 1701 cm⁻¹. -1 This is the stretching vibration peak of the carbonyl group (C=O) in the ester group, at 1599 cm⁻¹. -1 This is a stretching vibration peak at 1514 cm⁻¹, representing either an azo group (N=N) or an inter-ring (C=C) stretching vibration. -1 The peak represents the asymmetric stretching vibration of NO2, at 1327 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1229 cm⁻¹. -1 The peak for CN stretching vibration is 1101 cm⁻¹. -1 This is the peak of the CO stretching vibration in the ester group. Figure 4 It can be known that 3346cm -1 The peak represents the (NH) stretching vibration of the amide bond, at 1635 cm⁻¹. -1 This is the stretching vibration peak of the carbonyl group (C=O) in the ester group, at 1600 cm⁻¹. -1 This is a stretching vibration peak at 1510 cm⁻¹, representing either an azo group (N=N) or an inter-ring (C=C) stretching vibration.-1 The peak represents the asymmetric stretching vibration of NO2, at 1332 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1242 cm⁻¹. -1 The peak for CN stretching vibration is 1103 cm⁻¹. -1 This is the peak of the CO stretching vibration in the ester group. Figure 5 It can be known that 3304cm -1 The peak represents the (NH) stretching vibration in the amide bond, at 2974 cm⁻¹. -1 This is the stretching vibration of CH in the methylene group, 1631 cm⁻¹ -1 This is the stretching vibration peak of the carbonyl group (C=O) in the ester group, at 1598 cm⁻¹. -1 and 1566cm -1 This is a stretching vibration peak at 1510 cm⁻¹, representing either an azo group (N=N) or an inter-ring (C=C) stretching vibration. -1 The peak represents the asymmetric stretching vibration of NO2, at 1425 cm⁻¹. -1 This is the CN stretching vibration peak in the amide bond, 1332 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1230 cm⁻¹. -1 The peak for CN stretching vibration is 1097 cm⁻¹. -1 This is the CO stretching vibration peak in the ester group.

[0056] Adsorption performance tests of azo dyes on PET and PU fibers in Examples 1 and Comparative Examples 1-4: To understand the influence of various characteristic groups on the adsorption capacity and adsorption saturation value of PET and PU materials, adsorption isotherms were measured for dyeing PET fabrics and PU fibers.

[0057] The test method was as follows: Dye liquor containing a series of azo dyes at different concentrations was prepared. The concentration of ammonium sulfate in the dye liquor was 1 g / L, the pH of the system was adjusted to 5, the concentration of dispersant MF (sodium methylene dimethylnaphthalene sulfonate) was 1 g / L, and the liquor ratio was 50:1. The dyeing machine was heated to 70℃, and the PET fabric was placed in the dye cup and placed in the dyeing machine. After running for 5 minutes, the temperature was increased to 130℃ at a rate of 1℃ / min. PU fiber was dyed from room temperature, and the temperature was increased to 120℃ at a rate of 1℃ / min. After holding at these temperatures for 60 minutes to reach dyeing equilibrium, the temperature was lowered to 80℃ and the dyed samples were removed. The PET fabric samples were sequentially subjected to sodium hydrosulfite reduction cleaning and cold water cleaning. In the sodium hydrosulfite reduction cleaning, the concentration of sodium hydrosulfite was 2 g / L, the concentration of NaOH was 2 g / L, the liquor ratio was 50:1, the cleaning temperature was 85℃, and the cleaning time was 15 minutes. After cold water cleaning, the samples were air-dried. The PU fiber samples were directly rinsed with cold water and then air-dried.

[0058] Dye Adsorption Test: Accurately weighed (±0.1 mg) dyed samples were repeatedly stripped using N,N-dimethylformamide (DMF) solvent. The stripping process was as follows: 0.0200~0.0600 g of dyed fabric was weighed and placed in a 100 mL beaker. 5~10 mL of DMF solvent was added, and the mixture was heated on an electric furnace at 130℃ to allow the dye to be slowly extracted. This process was repeated three times until the sample became colorless. The extract was then diluted to a final volume, and its absorbance was measured using a UV-2450 spectrophotometer. The adsorption amount was calculated using the dye's working curve. The equilibrium adsorption amount on the fiber was then measured [D]. f ~Dye concentration in solution [D] s Adsorption isotherms were obtained by plotting the data. The adsorption isotherms for dyeing PET fabrics with azo dyes in Examples 1 and Comparative Examples 1-4 are shown below. Figure 6 As shown, the adsorption isotherms of the azo dyes used in Example 1 and Comparative Examples 1-4 for dyeing PU fibers are as follows: Figure 7 As shown, D1 is Comparative Example 1, D2 is Comparative Example 2, D3 is Comparative Example 3, D4 is Comparative Example 4, and D5 is Example 1.

[0059] pass Figures 6-7 The shapes reveal that, except for the hydroxyl-containing dye in Example 1, which exhibits a Nernst and Langmuir combined adsorption model on PET fabric, the dyes in Comparative Examples 1-4 all exhibit Nernst-type adsorption. This is because the dye in Example 1 contains hydroxyl groups at the molecular ends, resulting in strong hydrogen-bonded localized adsorption with PET fibers. Further analysis of the above adsorption isotherm data yields adsorption performance parameters such as partition coefficient, affinity, and saturated adsorption capacity, as shown in Table 1.

[0060] Table 1. Partition coefficient, affinity, and saturated adsorption capacity of dyes on different fibers

[0061] Table 1 shows that, under the same color-developing matrix, the characteristic groups have a significant impact on the dyeing performance of PET fabrics and PU fibers. The comparison reveals that the amide-containing disperse dye in Comparative Example 3 has a high affinity for both materials, but its saturation adsorption capacity is not ideal, especially for PET fabric, where it is only at a moderate level. The urea-containing disperse dye in Comparative Example 4, while exhibiting the highest saturation adsorption capacity on PU fibers, has the lowest saturation adsorption capacity on PET fabrics. This is related to the hydrophilic tendency of urea itself, resulting in poor affinity for the hydrophobic PET fiber. The dye containing urethane characteristic groups in Comparative Example 2, due to its similarity to the characteristic groups of PU fibers, shows the highest affinity, but its saturation adsorption capacity is not ideal in all cases. In Example 1, the ester-containing disperse dye did not exhibit the highest affinity or saturated adsorption capacity for either material. In Example 1, the hydroxyl-containing dye, due to its tendency to form hydrogen bonds with water molecules, did not have the highest affinity for either material, but its saturated adsorption capacity was relatively high. The adsorption saturation value on PU fiber was 41.5 g / kg, and the adsorption on PET fabric followed a complex model: part of the dye was adsorbed using the Langmuir model with a saturation value of 11.73 g / kg, while the remaining dye was adsorbed using the Nernst model. The adsorption capacity increased linearly with increasing dye concentration. Even when the total adsorption reached 28.72 g / kg, saturation was not yet achieved, significantly exceeding that of the dyes in Comparative Examples 1-4. Based on the above experimental results, it was found that the hydroxyl-containing disperse dye has a high saturated adsorption capacity for both materials, making it suitable for deep-dark dyeing of PET microfiber PU resin imitation suede fabric.

[0062] Tests on the improvement of dyeing of imitation suede fabrics by azo dyes in Examples 1 and 1-4: Azo disperse dyes containing different characteristic groups, as described in Example 1 and Comparative Examples 1-4, were used to conduct dyeing enhancement tests on imitation suede fabric. The dye liquor concentration was varied, but the same dyeing process was used. Dyeing began at 70°C, and the temperature was increased to 130°C at a rate of 1°C / min. After holding at this temperature for 40 minutes, the temperature was lowered to 80°C before the fabric was removed. The color depth value (K / S value) of each dyed sample was measured, and the corresponding dye concentration (owf) was plotted to obtain enhancement curves. The results are shown below. Figure 8 As shown, D1 is Comparative Example 1, D2 is Comparative Example 2, D3 is Comparative Example 3, D4 is Comparative Example 4, and D5 is Example 1.

[0063] from Figure 8The data shows that among the five dyes, the urea-containing dye D4 has the worst color enhancement, with the highest color depth (K / S value) at a dye concentration of 3% (owf) (10.19); followed by the amide-containing dye D3, with the highest color depth (K / S value) at a dye concentration of 3.5% (owf) (13.33); the urethane-containing dye D2 and the ester-containing dye D1 are at a medium level, with the highest color depth values ​​at 2% (owf) and 4% (owf) (13.72 and 15.01, respectively); the best color enhancement is the hydroxyl-containing dye D5 from Example 1, with the highest color depth value at a dye concentration of 6% (owf), and its K / S value of 37.60, which is much higher than the highest color depth values ​​of the other four dyes. This result is basically consistent with the saturation adsorption test results of the two materials, PET fabric and PU fiber. The saturation adsorption of hydroxyl dyes is high for both materials, and the dyeing improvement of imitation suede fabric is the best. This further verifies that hydroxyl disperse dyes are suitable for dyeing imitation suede fabric in dark and deep colors.

[0064] The rubbing fastness and color migration fastness of the imitation suede fabric were important performance indicators. The color fastness of the imitation suede fabric dyed with the highest color depth values ​​of the azo dyes in Example 1 and Comparative Examples 1-4 was tested. The test standard methods were as follows: the rubbing fastness was tested according to the standard "ISO 105-X12 Textiles - Tests for color fastness X12 - Part 1: Color fastness to rubbing"; the color migration fastness was tested according to the standard "AATCC 163-2013 Method I: Color fastness - Dye transfer from fabric to fabric during storage". The results are shown in Table 2.

[0065] Table 2. Color fastness properties of disperse dyes containing different characteristic groups on suede-like dark-dyed samples.

[0066] As can be seen from the fastness performance results in Table 2, Example 1, which contains hydroxyl dyes, has excellent rubbing fastness and color migration fastness performance. However, the four dyes in Comparative Examples 1 to 4 have low rubbing fastness and color migration fastness due to severe surface adsorption, and are not suitable for dyeing dark colors of imitation suede fabrics.

[0067] Example 2

[0068] 10 mmol of o-chloro-p-nitroaniline was added to a 50 mL three-necked flask, followed by 10 mL of water and 5 mL of concentrated hydrochloric acid. Stirring was started, and the mixture was heated in a water bath to 80 °C. After dissolution, the solution was cooled to 0–5 °C in an ice bath to obtain an o-chloro-p-nitroaniline solution. 10.5 mol of sodium nitrite was dissolved in 3 mL of water, and the sodium nitrite solution was slowly added dropwise to the o-chloro-p-nitroaniline solution. The reaction was continued at 0–5 °C for 2 h. The reaction progress was monitored using an amino reagent (p-dimethylaminobenzaldehyde). After the reaction was complete, excess sodium nitrite was quenched by adding aminosulfonic acid.

[0069] Add 60 mL of water, 4 mL of concentrated sulfuric acid, and 3 drops of AEO-9 to a 500 mL three-necked flask. Start stirring and add 10 mmol of the coupling component, stirring at room temperature until dissolved. Cool the mixture to 0–10 °C in an ice bath. Slowly add the diazonium salt solution dropwise into the cooling solution, adding crushed ice to maintain the temperature at 0–10 °C during the addition process. The addition time is 30 min. After the addition is complete, maintain the reaction in an ice bath for 2 h, then remove the ice bath and continue the reaction for another 2 h. Filter the solution and purify it using DMF-water recrystallization to obtain the azo dye (Disperse Orange A).

[0070] The structural formulas of the coupling component and the azo dye are as follows: , .

[0071] Example 3

[0072] Add 5 mL of concentrated sulfuric acid to a 50 mL three-necked flask, start stirring, and slowly add 10 mmol of benzisothiazol to the flask. After dissolution, cool to 0–5 °C in an ice bath, add 2.5 mL of nitrosylsulfonic acid dropwise, and continue the reaction at 0–5 °C for 2 h. The reaction endpoint is detected by the ice-water method. Other conditions are the same as in Example 2, and the azo dye (Disperse Blue A) is obtained.

[0073] The structural formula of azo dyes is: .

[0074] The two dyes synthesized in Examples 2 and 3 were analyzed using an infrared spectroscopy analyzer, and the results are as follows: Figure 9 , 10 As shown. By Figure 9 Analysis shows that 3363cm -1 The peak represents the stretching vibration of the hydroxyl group (OH), at 3099 cm⁻¹. -1 This is the stretching vibration of the benzene ring CH, 2914 cm⁻¹ -1 This is the stretching vibration of CH in the methylene group, 2248 cm⁻¹ -1 The peak is the stretching vibration peak of cyano (CN), at 1605 cm⁻¹. -1 This is a stretching vibration peak at 1512 cm⁻¹, representing either an azo group (N=N) or an inter-ring (C=C) stretching vibration. -1 The peak represents the asymmetric stretching vibration of NO2, at 1400 cm⁻¹. -1 The peak for OH bending (in-plane) vibration is 1364 cm⁻¹. -1 This is a symmetrical stretching vibration of NO2, 1152 cm. -1 This is a CN stretching vibration, 1047 cm. -1 This is the CO stretching vibration in the ester group. Figure 10 Analysis shows that 3416cm -1The peak is the stretching vibration peak of the hydroxyl group (OH), at 3094 cm⁻¹. -1 This is the stretching vibration of the benzene ring CH, 2935 cm⁻¹ -1 This is the stretching vibration of CH in the methylene group, 2246 cm⁻¹ -1 The peak is the stretching vibration peak of the cyano group (CN), at 1594 cm⁻¹. -1 The peak represents the stretching vibration of an azo group (N=N) or between benzene rings (C=C), at 1548 cm⁻¹. -1 This is the (C=N) stretching vibration peak in benzisothiazol, at 1514 cm⁻¹. -1 The peak represents the asymmetric stretching vibration of NO2, at 1398 cm⁻¹. -1 The peak represents the OH bending (in-plane) vibration at 1325 cm⁻¹. -1 The peak represents the symmetrical stretching vibration of NO2, at 1245 cm⁻¹. -1 The peak value is for the C-C stretching vibration, at 1138 cm⁻¹. -1 The peak for CN stretching vibration is 1049 cm⁻¹. -1 This is the CO stretching vibration peak in the ester group.

[0075] Dye performance tests of imitation suede fabrics using dyes from Examples 2 and 3: The faux suede fabric was dyed using two disperse dyes from Examples 2 and 3. The lifting properties, rubbing fastness, and color migration fastness were measured, and the results are as follows: Figure 11 As shown in Table 3.

[0076] from Figure 11 The data shows that both hydroxyl-containing dyes exhibited excellent color enhancement when used for dyeing imitation suede fabric. The highest color depth values ​​were reached at dye concentrations of 5% (owf) and 6.5% (owf), respectively, with K / S values ​​exceeding 32 and 28 for Disperse Orange A and Disperse Blue A. This further demonstrates that both aromatic amine diazo components (Disperse Orange A) and heterocyclic amine diazo components (Disperse Blue A), as long as the coupling component contains a hydroxyl group at its end, can achieve good color enhancement when dyeing imitation suede fabric. They are suitable for dyeing dark-colored imitation suede fabrics, and both rubbing fastness and color migration fastness reach level 4 or higher (see Table 3), effectively meeting the product quality requirements for dark-colored imitation suede fabrics.

[0077] Table 3. Color fastness properties of suede-like samples dyed with hydroxyl-containing disperse dyes.

[0078] The hydroxyl-containing disperse dyes of this invention can achieve deep and dark color dyeing of suede-like fabrics, with a complete color spectrum, which can meet the needs of actual production.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes, characterized in that, Simply mix the azo dye, auxiliaries, and water, then add the mixture to the fabric for dyeing. The structural formula of the azo dye used in PET microfiber PU resin suede-like fabric is: ； Wherein, R is H, CH3 or OCH3, and X is H or CN; The structural formula for Ar is: , , or ; R1 and R2 can be H, Cl, Br, CN, or NO2 independently.

2. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes as described in claim 1, characterized in that, The preparation method of azo dyes for PET microfiber PU resin suede-like fabrics includes the following steps: 1) Preparation of diazonium salt solution: Method 1: Dissolve the diazonium component in water and concentrated hydrochloric acid, then cool to obtain a diazonium solution. Add an aqueous solution of sodium nitrite dropwise to the diazonium solution, continue the reaction, and then quench the sodium nitrite to obtain a diazonium salt solution. The diazo component is p-nitroaniline or o-chloro-p-nitroaniline; Method 2: Dissolve the diazonium component by adding it dropwise to concentrated sulfuric acid, then cool it. Add nitrite sulfuric acid dropwise to the cooling liquid and continue the reaction to obtain a diazonium salt solution. The structural formula of the diazo component is: The structural formula of the diazonium salt is: ; The structural formula of Ar is: , , or ; R1 and R2 are independently Br, CN or NO2; 2) Preparation of azo dyes: The coupling component was dissolved in water and acid and then cooled in an ice bath to obtain a cooling solution. The diazonium salt solution was added dropwise to the cooling solution. After the addition was completed, the reaction was carried out in an ice bath. Then the ice bath was removed and the reaction continued to obtain the azo dye. The structural formula of the coupling component is: ； Where R is H, CH3 or OCH3, and X is H or CN.

3. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes according to claim 2, characterized in that, In step 1) of method one, the molar volume ratio of the diazo component, water and concentrated hydrochloric acid is 10 mmol: 10~15 mL: 4~6 mL; the molar ratio of sodium nitrite and diazo component is 10~11 mol: 10 mmol.

4. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes according to claim 2 or 3, characterized in that, In step 1) of method one, the dissolution temperature is 60~80℃, the cooling temperature is 0~5℃, the reaction continues at 0~5℃, the reaction continues for 1.5~2.5h, and the quenching reagent is aminosulfonic acid.

5. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes according to claim 2, characterized in that, In step 1) of method two, the molar volume ratio of the diazo component to concentrated sulfuric acid is 10 mmol: 4~6 mL; the molar volume ratio of the diazo component to nitrosyl sulfuric acid is 10 mmol: 2~2.5 mL.

6. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dye according to claim 2 or 5, characterized in that, In step 1) of method two, the cooling temperature is 0~5℃, the reaction temperature is 0~5℃, and the reaction time is 1.5~2.5h.

7. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes according to claim 2, characterized in that, Step 2) The molar volume ratio of the coupling component, water, and acid is 10~10.3 mmol: 40~60 mL: 2~5 mL; the acid is hydrochloric acid or concentrated sulfuric acid. The ice bath cooling temperature is 0~10℃, the ice bath reaction time is 1.5~2.5h, and the reaction time is 2~4h after the ice bath is removed.

8. The method for deep dyeing PET microfiber PU resin imitation suede fabric with azo dyes according to claim 1, characterized in that, The initial dyeing temperature is 65~75℃, the dyeing temperature is 125~135℃, the dyeing time is 30~60min, and the rate of heating to the dyeing temperature is 1~3℃ / min.

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