A method for efficiently deepening polylactic acid fabric

Abstract

The application discloses a method for efficiently deepening polylactic acid fabric. The dyeing method comprises the following steps: (1) preparing a modified solvent (i.e. a deep eutectic solvent); (2) placing the polylactic acid fabric in the modified solvent for modification treatment, rinsing the treated fabric with distilled water after the modification is completed, and obtaining a polylactic acid modified fabric; and (3) placing the polylactic acid modified fabric in a dye bath for dyeing, washing with hot water and cold water after the dyeing is completed, drying, and obtaining a polylactic acid dyed fabric. The long-chain structure of the polylactic acid is destroyed, the crystallinity of the polylactic acid is changed, the polylactic acid is hydrophilized, the dyeing sites are increased, and the dyeing effect of the polylactic acid fabric is improved through the DES modification treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of textile material processing, and particularly relates to a method for efficiently deepening polylactic acid fabric. BACKGROUND

[0002] With the emphasis on energy crisis and environmental governance and the promotion of the concept of sustainable development, bio-based polymers (such as bio-based polyester, polylactic acid, bio-based polyamide and bio-based polyethylene) made of renewable plant raw materials (such as wheat, corn and sugarcane) have attracted extensive attention. As a kind of lightweight, biodegradable and compostable semi-crystalline bio-based plastic, polylactic acid has characteristics such as comparable transparency and excellent mechanical properties to traditional resins, and can be used in a series of applications such as agriculture, medicine, packaging and textiles, and is considered as a potential alternative to petroleum-based plastics. However, the potential of polylactic acid as a substitute for petroleum-based plastics has not been fully realized, and one of the main obstacles is the dyeing of polylactic acid fibers. The main problems of polylactic acid difficult to dye are: high crystallinity is not conducive to the adsorption of dyes, there are more ester groups and methyl groups in the fiber to produce non-hydrophilic groups, long chains make it difficult for dyes to penetrate, and the dyeing rate is low. In view of the above three problems, the present application attempts to destroy the long chain structure, change the crystallinity of polylactic acid, form hydrophilization, increase the dyeing site, and improve the dyeing effect of polylactic acid fabric.

[0003] In order to achieve the above effects, the methods that can be used mainly include "copolymerization", "copolymerization + chemical grafting", "blending modification", "surface modification and modification". Onur Baykus added octaammonium polyhedral oligomeric silsesquioxane (OA-POSS) nanoparticles in the melt spinning process to improve the dyeability of polylactic acid fibers to anionic dyes, but it only increases the dyeing site of anionic dyes. Relatively speaking, the "surface modification and modification" method is more environmentally friendly and less restricted. The methods of surface modification and modification mainly include surface chemical grafting, coating, low-temperature plasma, ultraviolet radiation, ultrasonic wave, etc. Plasma treatment, low-temperature plasma high-energy particles bombard the surface of the fiber, etch and crosslink the surface, which can achieve the purpose of hydrophilic modification, but different materials have different time effectiveness for hydrophilic modification. Alkali reduction treatment is a common treatment method in industry, which hydrolyzes and breaks the ester bond of the molecular chain by alkaline substances, continuously forms hydrolysis products with different polymerization degrees and neutralizes the carboxylic acid generated by hydrolysis, but it generally causes greater damage to the fabric.

[0004] Deep eutectic solvents (DESs) are a new type of ionic liquid (IL) analogues, which are considered as another new type of environmentally friendly liquid materials in addition to traditional ILs. DESs are formed by the combination of hydrogen bond acceptors and hydrogen bond donors through hydrogen bonding forces, which do not need further purification by organic solvents and subsequent treatment, and can be used after synthesis with 100% atom utilization, so they are truly green solvents. Similar to ILs, DESs have low vapor pressure, high thermal stability, non-flammability and easy preparation. In addition, DESs also have the advantages of low price, non-toxicity and biodegradability. Literature shows that coating DESs on hydrophobic surfaces such as wood, polyamide films and PET can improve the surface smoothness and surface wettability, and also lead to the generation of additional functional groups such as -OH and / or -COOH on the hydrophobic surface, which can interact with water molecules through hydrogen bonds, resulting in an increase in the hydrophilicity of the plastic surface. Based on this, the present application uses DES solvent to modify polylactic acid fabric, which causes surface physical etching and chemical modification to destroy the long-chain structure of polylactic acid, change the crystallinity of polylactic acid, form hydrophilization, and increase the dyeing sites, thereby improving the dyeing effect of polylactic acid fabric. SUMMARY

[0005] The purpose of the present application is to provide a method for efficiently deepening polylactic acid fabric. First, the hydrogen bond acceptor and donor are heated and stirred to be clear to form a deep eutectic solvent, and then modification and dyeing are performed to obtain a polylactic acid dyed fabric. Through DES modification, surface physical etching and chemical modification occur to destroy the long-chain structure of polylactic acid molecules, change the crystallinity of polylactic acid, form hydrophilization, and provide polylactic acid fabric with more dyeing sites. The polylactic acid dyed fabric obtained by the method has good color depth and stability.

[0006] The present application adopts the following technical solutions:

[0007] A method for efficiently deepening polylactic acid fabric, comprising the following steps:

[0008] (1) configuring a deep eutectic solvent by heating and stirring a hydrogen bond acceptor and a donor to be clear;

[0009] (2) placing polylactic acid fabric in the deep eutectic solvent for modification treatment, rinsing the treated fabric with distilled water after modification is completed, and obtaining a polylactic acid modified fabric;

[0010] (3) placing the polylactic acid modified fabric in a dye bath and dyeing it using a direct dyeing method, and obtaining a polylactic acid dyed fabric after washing with hot water, cold water, and drying.

[0011] Further, the low eutectic solvent in the step (1) contains hydrogen bond acceptors and donors, the hydrogen bond acceptors include one or more of quaternary ammonium salt (such as choline chloride), zwitterion (such as betaine), etc., and the hydrogen bond donors include one or more of urea, thiourea, carboxylic acid (benzoic acid, malic acid, citric acid, succinic acid, oxalic acid, etc.), polyhydric alcohol (ethylene glycol, glycerol, butanediol, xylitol, etc.), amino acid, sugar (glucose, fructose), trifluoroacetamide, etc.

[0012] Further, the ratio of hydrogen bond acceptors and donors in the low eutectic solvent in the step (1) is 1:1 (molar ratio), and the reaction temperature is 70-90℃.

[0013] Further, the low eutectic solvent obtained in the step (1) needs to be diluted with deionized water to a mass percentage of 10-30%, and if it is not diluted directly, the subsequent effect cannot be achieved.

[0014] Further, the treatment temperature in the step (2) is 50-70℃, and the treatment time is 4-20h.

[0015] Further, the dyeing in the step (3) contains dyes and pH adjusters, wherein the amount of dyes added is 2-5% (o.w.f), the bath ratio is 1:30-1:50, and the pH is 4-7.

[0016] Further, the pH adjuster is one or more of sodium acetate solution and glacial acetic acid solution.

[0017] Further, the dyeing process in the step (3) is: dyeing at room temperature, heating at 1-3℃ / min, keeping at 90-100℃ for 30-60min, cooling at 1-3℃ / min, and taking out at 50℃ and washing with hot water (50-60℃) and cold water (30-10℃).

[0018] Due to the above technical scheme, the following beneficial effects are achieved:

[0019] The hydrogen bond acceptor and donor are heated and stirred to be clear, configured into a deep eutectic solvent, the surface of the polylactic acid fabric is physically etched and chemically modified by using the DES, more dyeing sites are given to the polylactic acid fabric, so that the color depth and stability of the polylactic acid fabric are improved. After DES treatment, part of the surface of the polylactic acid fabric is obviously etched, the surface roughness is increased, which is beneficial to the spreading of liquid drops; after DES treatment, the long chain of the polylactic acid is broken, the number of polar groups is increased, the crystallinity is reduced, and the amorphous region of the fiber is increased, so that the dye molecules can more easily enter the inside and be closely combined with the sites in the dyeing stage. The dye sites increased by this method do not have time effectiveness, the polylactic acid dyed fabric has good color depth and stability, the process operation is simple, the damage to the fabric is small, the equipment requirement is low, the raw material has universality, and the use is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described below in combination with the drawings:

[0021] Figure 1 It is the real object diagram of the polylactic acid dyed fabric before and after modification in Example 1.

[0022] Figure 2 It is the K / S curve of the polylactic acid dyed fabric before and after modification in Example 1. SPECIFIC IMPLEMENTATION METHOD

[0023] The technical solutions of the application will be further described below in combination with the drawings and specific examples:

[0024] In the following examples, unless otherwise specified, the reagents, materials and devices used can be purchased from commercial channels or prepared by conventional methods.

[0025] Example 1

[0026] (1) The deep eutectic solvent is configured, choline chloride and oxalic acid (1:1 molar ratio) are heated and stirred to be clear at 80 DEG C and 30 rpm;

[0027] (2) The polylactic acid fabric is placed in a beaker containing 10% DES solvent solution (liquid-fabric ratio = 30:1) diluted with water, and is placed at 60 DEG C for 16 hours, then the treated fabric is washed clean with distilled water and dried at 80 DEG C, and the polylactic acid modified fabric is obtained;

[0028] (3) Curcumin is dissolved in water and ethanol, the volume ratio of ethanol to water is 1:1, and glacial acetic acid is used to adjust the pH, so that the pH value of the dye bath is 5;

[0029] (4) the polylactic acid modified fabric is placed in a dye bath to perform dyeing by using a direct dyeing method, the dye concentration in the dyeing solution is 2% (o.w.f), the bath ratio is 1:50, the dyeing temperature is 95 DEG C, the dyeing time is 40 min, and after the dyeing is completed, the polylactic acid dyed fabric is washed by hot water, cold water and dried to obtain the polylactic acid dyed fabric.

[0030] Through testing, the K / S value of the polylactic acid fabric is 21.97, no damage is observed on the fabric surface, and the K / S value is 21.46 after 10 times of deionized water washing, indicating that the polylactic acid fabric has good color depth and stability.

[0031] In addition, the polylactic acid fabric in Example 1 is not modified, and the remaining steps are unchanged, and finally the K / S value of the dyed polylactic acid fabric is 6.95, no damage is observed on the fabric surface, and the K / S value is 6.03 after 10 times of deionized water washing, indicating that the modification method of the application can increase the color depth and stability of the polylactic acid fabric.

[0032] In addition, in step (3) of Example 1, the pH is 8, and the remaining steps are unchanged, and finally the K / S value of the dyed polylactic acid fabric is 1.13, no damage is observed on the fabric surface, and the K / S value is 0.95 after 10 times of deionized water washing, indicating that dyeing under alkaline conditions cannot obtain good color depth. In addition, in step (4) of Example 1, the dyeing temperature is 70 DEG C, and the remaining steps are unchanged, and finally the K / S value of the dyed polylactic acid fabric is 2.03, no damage is observed on the fabric surface, and the K / S value is 1.97 after 10 times of deionized water washing, indicating that dyeing cannot obtain good color depth when the dyeing temperature is too low.

[0033] The dyeing process in the application should be carried out under acidic conditions, and the dyeing temperature should not be lower than 88 DEG C, otherwise the effect is poor.

[0034] Example 2

[0035] (1) The eutectic solvent is configured, and choline chloride and succinic acid (1:1 molar ratio) are heated and stirred at 80 DEG C and 30 rpm until clear;

[0036] (2) The polylactic acid fabric is placed in a beaker containing a 20% DES solvent solution (liquid-fabric ratio = 30:1) after dilution with water, and is placed at 60 DEG C for 12 hours, then the treated fabric is washed with distilled water and dried at 80 DEG C to obtain the polylactic acid modified fabric;

[0037] (3) The cochineal red is dissolved in water, and glacial acetic acid is used to adjust the pH, so that the dye bath pH value is 5;

[0038] (4) The polylactic acid modified fabric is dyed in a dye bath by direct dyeing method, the dye concentration in the dyeing solution is 2% (o.w.f), the bath ratio is 1:50, the dyeing temperature is 95°C, the dyeing time is 40 min, and after dyeing, the polylactic acid dyed fabric is obtained after hot water washing, cold water washing and drying.

[0039] Test results show that the K / S value of the polylactic acid modified fabric is 2.07, no damage is observed on the fabric surface, and the K / S value is 2.03 after 10 times of deionized water washing, and the K / S value of the polylactic acid fabric is 0.84, indicating that this modification method can increase the color depth and stability of the polylactic acid fabric.

[0040] Example 3

[0041] (1) The eutectic solvent is configured, and choline chloride and succinic acid (1:1 molar ratio) are heated and stirred at 80°C and 35 rpm until clear;

[0042] (2) The polylactic acid fabric is placed in a beaker containing 10% DES solvent solution (liquid-fabric ratio = 30:1) diluted with water, and is placed at 60°C for 12 hours, then the treated fabric is washed with distilled water and dried at 80°C to obtain the polylactic acid modified fabric;

[0043] (5) Curcumin is dissolved in water and ethanol, the volume ratio of ethanol to water is 1:1, and glacial acetic acid is used to adjust the pH, so that the pH value of the dye bath is 5;

[0044] (3) The polylactic acid modified fabric is dyed in a dye bath by direct dyeing method, the dye concentration in the dyeing solution is 2% (o.w.f), the bath ratio is 1:50, the dyeing temperature is 90°C, the dyeing time is 40 min, and after dyeing, the polylactic acid dyed fabric is obtained after hot water washing, cold water washing and drying.

[0045] Test results show that the K / S value of the polylactic acid modified fabric is 15.73, no damage is observed on the fabric surface, and the K / S value is 15.56 after 10 times of deionized water washing, indicating that it has good color depth and stability.

[0046] Example 4

[0047] (1) The eutectic solvent is configured, and choline chloride and succinic acid (1:1 molar ratio) are heated and stirred at 80°C and 35 rpm until clear;

[0048] (2) The polylactic acid fabric is placed in a beaker containing 10% DES solvent solution (liquid-fabric ratio = 30:1) diluted with water, and is placed at 60°C for 12 hours, then the treated fabric is washed with distilled water and dried at 80°C to obtain the polylactic acid modified fabric;

[0049] (6) Dissolve curcumin in water and ethanol, the volume ratio of ethanol and water is 1:1, use glacial acetic acid to adjust pH, make the pH of dye bath 6;

[0050] (3) Put the polylactic acid modified fabric into the dye bath to dye by direct dyeing method, the concentration of dye in the dyeing solution is 4% (o.w.f), the bath ratio is 1:50, the dyeing temperature is 90 DEG C, the dyeing time is 40 min, after dyeing, wash by hot water and cold water, dry to obtain polylactic acid dyed fabric.

[0051] Test shows that the K / S value of polylactic acid modified fabric is 22.35, no damage is observed on the surface of fabric, the K / S value is 22.07 after washing by deionized water for 10 times, which shows that it has good color depth and stability.

[0052] The above is only a specific embodiment of the present application, but the technical features of the present application are not limited to this. Any simple change, equivalent replacement or modification made on the basis of the present application to solve the basically same technical problem and realize the basically same technical effect is covered in the protection scope of the present application.

Claims

1. A method for efficiently deepening polylactic acid fabrics, characterized in that: Includes the following steps: (1) Preparation of eutectic solvent: Heat and stir the hydrogen bond acceptor and hydrogen bond donor until clear. The resulting eutectic solvent needs to be diluted with deionized water to a mass percentage of 10-30%. (2) The polylactic acid fabric was placed in a eutectic solvent for modification treatment. The modification treatment temperature was 50-70 ℃ and the treatment time was 4-20 h. After modification, the treated fabric is rinsed with distilled water to obtain polylactic acid modified fabric; (3) The polylactic acid modified fabric is placed in a dye bath and dyed by direct dyeing. After dyeing, it is washed with hot water and cold water and dried to obtain polylactic acid dyed fabric. The dye in the dye bath is curcumin or carmine, the amount of dye added is 2-5% owf, and the bath ratio is 1:30-1:

50.

2. The method for efficiently deepening polylactic acid fabrics according to claim 1, characterized in that: The eutectic solvent in step (1) contains hydrogen bond acceptors and hydrogen bond donors. The hydrogen bond acceptors are one or more of quaternary ammonium salts and zwitterions, and the hydrogen bond donors are one or more of urea, thiourea, carboxylic acid, polyols, amino acids, sugars, and trifluoroacetamide.

3. The method for efficiently deepening polylactic acid fabrics according to claim 1, characterized in that: In step (1), the molar ratio of hydrogen bond acceptor to hydrogen bond donor in the eutectic solvent is 1:1, and the reaction temperature is 70-90℃.

4. The method for efficiently deepening polylactic acid fabrics according to claim 1, characterized in that: The dye bath in step (3) contains dye and pH adjuster, with a pH value of 4-7.

5. The method for efficiently deepening polylactic acid fabrics according to claim 4, characterized in that: The pH adjuster is one or more of sodium acetate solution and glacial acetic acid solution.

6. The method for efficiently deepening polylactic acid fabrics according to claim 1, characterized in that: The dyeing process in step (3) is as follows: dyeing at room temperature, heating at 1-3 ℃ / min, holding at 90-100℃ for 30-60 min, cooling at 1-3 ℃ / min, and taking out at 50℃ for washing with hot and cold water.

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