CN117306241A - Method for hydrophilically modifying polyester by combining DES (DES) ultrasonic pretreatment and enzyme - Google Patents

Abstract

The invention discloses a method for hydrophilically modifying terylene by DES ultrasonic pretreatment and enzyme combination, belonging to the technical field of surface modification. The invention relates to a polyester hydrophilic modification method, which comprises the steps of putting refined polyester fabric into a DES solvent for ultrasonic treatment, washing and drying after the treatment is finished; placing the dried polyester fabric into a Tris-HCl buffer solution with the pH of 5mmol/L, adding a Hic cutinase enzyme solution for hydrolysis reaction, inactivating reaction residual liquid after the reaction is finished, washing and drying the fabric; the hydrogen bond donor of the DES solvent is an alcohol or amide monomer, and the hydrogen bond acceptor is one or two of choline chloride, betaine and choline dihydrogen citrate; compared with the traditional chemical modification method, the method is environment-friendly, pollution-free, small in influence on mechanical properties, and mild and efficient in modification effect.

Description

A method for hydrophilic modification of polyester using DES ultrasonic pretreatment combined with enzymes

Technical field

The invention relates to a method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzyme, and belongs to the technical field of surface modification.

Background technique

Polyester (PET) is an important variety of synthetic fibers. It is widely used in the textile industry due to its excellent physical and chemical properties such as high tensile strength, good dimensional stability, wear resistance, washability, etc. However, the polyester molecular chain contains a large number of ester groups, with only two terminal alcohol hydroxyl groups and no other polar groups. This makes pure polyester fabrics extremely poor in hydrophilicity, difficult to dye, and feels stuffy when worn, which limits the use of polyester in the industry. Used in many textile applications such as sportswear, bedding, etc.

Due to the wide application of PET, the wettability of its fabrics is an important topic in basic and applied research. In recent years, the surface hydrophilic modification methods of polyester fibers, mainly polyester, are mainly divided into the following methods: surface oxidation method, surface coating method, surface grafting method, alkali reduction treatment, and biological modification method. , such as enzymatic modification, etc.; however, these modification methods still have technical flaws, such as the alkali reduction and finishing process which consumes a large amount of alkali and water, and discharges a large amount of wastewater containing concentrated alkali and high oligomer content, which damages the environment; pro- Aqueous coating has problems such as poor water resistance, the use of many chemicals that are not easy to degrade, and the timeliness of the UV graft modification effect.

Contents of the invention

In the existing technology, the alkaline hydrolysis method has a greater impact on the mechanical properties of the fabric, and the wastewater containing a large amount of chemical substances is discharged to pollute the environment; the surface coating method has poor water resistance, and the coated chemical substances are not easy to degrade in the environment; simply using The hydrophilic modification of polyester by biological enzymes has the problem of poor modification effect.

In order to solve at least one of the above problems, the present invention uses the biodegradable solvent DES to conduct ultrasonic pretreatment of the polyester fabric, and then uses cutinase to perform enzymatic hydrolysis to improve the hydrophilicity of the polyester fabric.

The first object of the present invention is to provide a method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzymes. The method includes the following steps:

(1) Preparation of DES solvent

Add the hydrogen bond donor and hydrogen bond acceptor into the beaker, stir and dissolve until it is clear and transparent, and the DES solvent is obtained; the hydrogen bond donor is alcohol or amide monomer; the hydrogen bond acceptor is choline chloride and betaine , one or two of choline citrate;

(2) Put the refined polyester fabric into the DES solvent prepared in step (1) for ultrasonic treatment. After the treatment, wash and dry;

(3) Put the polyester fabric dried in step (2) into Tris-Hcl buffer, add Humicolainsolens cutinase enzyme solution for hydrolysis reaction, after the reaction is completed, inactivate the reaction residue, wash and dry the fabric , that’s it.

In one embodiment, the hydrogen bond donor in step (1) is one or more of glycerol, ethylene glycol, urea, sorbitol, xylitol, glucose and triethanolamine.

In one embodiment, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor in step (1) is 1:1-2.

In one embodiment, the temperature during the preparation and stirring process of the DES solvent in step (1) is 80-100°C.

In one embodiment, the refined polyester fabric in step (2) refers to adding 3-6g/L soap flakes to the polyester fabric in deionized water with a bath ratio of 1:40-60, and 3-6g/L soap flakes in deionized water. Water sodium carbonate, refining in a constant temperature water bath at 80~100℃ for 30min~1h, washing with deionized water, drying in an oven at 80~100℃ to constant weight, and balancing under the conditions of temperature and humidity of 25±1℃ and 65±2% Obtained in 24 hours; further preferably, the liquor ratio is 1:30, add 5g/L soap flakes, 4g/L anhydrous sodium carbonate, refine at 98°C for 30min, and dry at 80°C.

In one embodiment, the liquor ratio of the refined polyester fabric and the DES solvent in step (2) is 1:40.

In one embodiment, the ultrasonic treatment conditions in step (2) are 0.5-8 hours at 30-70°C and a power of 200-1000W; further preferably, the reaction is 30 minutes at 50°C and a power of 1000W.

In one embodiment, the washing in step (2) refers to washing the fabric with deionized water.

In one embodiment, the drying temperature in step (2) is 60-70°C.

In one embodiment, the Humicola insolens cutinase described in step (3) has an enzyme activity of 1000-2000 U/mL and an enzyme dosage of 100 U/mL.

In one embodiment, the Tris-HCl buffer in step (3) has a pH of 7 to 9, preferably 8, and a concentration of 5 mmol/L.

In one embodiment, the hydrolysis reaction bath ratio in step (3) is 1:40, the temperature is 60-65°C, and the time is 18-24 hours.

In one embodiment, the specific operation of inactivation in step (3) is to heat the reaction residue in a constant temperature water bath at 100°C for 30 minutes.

In one embodiment, the washing in step (3) refers to washing the fabric with deionized water.

In one embodiment, the drying temperature in step (3) is 60-70°C.

The second object of the present invention is to provide a hydrophilic polyester obtained by the above modification method.

The third object of the present invention is to provide an application of the hydrophilic polyester fabric obtained by the above method in the textile field.

In one embodiment, the textile field includes household and industrial textile fields.

Beneficial effects of the present invention:

(1) The present invention uses a deep eutectic solvent (DES) to pretreat polyester fabrics. The solvent is simple to prepare, low in cost, biodegradable, and recyclable. The modification conditions are simple and environmentally friendly;

(2) The present invention uses Hic cutinase to catalyze the hydrolysis of the ester bonds on the surface of the polyester fabric, causing the polyester surface to generate hydrophilic groups such as hydroxyl and carboxyl groups, so that the polyester can be hydrophilically modified while maintaining its own advantageous properties. Effect;

(3) The amount of product released from the polyester fabric pretreated by DES in the present invention is significantly improved compared to the polyester without pretreatment. Compared with the traditional chemical modification method, it has less impact on the mechanical properties and is gentle and efficient.

(4) The present invention uses DES to pretreat polyester, and performs enzymatic hydrolysis on the polyester fabric after DES pretreatment. The release amount of enzyme hydrolyzate products is increased by 148.45% compared with no pretreatment; the enzymatic hydrophilicity angle after DES pretreatment is increased from 89.8° dropped to 86.5°.

Description of the drawings

Figure 1 is a graph showing the test results of the contact angle of the hydrophilic modified polyester fabric obtained by enzymatic hydrolysis after pretreatment in Example 1 and the polyester fabric in Comparative Example 1 after enzymatic hydrolysis without pretreatment; (a) is Comparative Example 1; (b) is Example 1;

Figure 2 is a scanning electron microscope image of the fabric obtained in Example 1 and Comparative Example 1; (a) is Example 1; (b) is Comparative Example 1;

Figure 3 is a graph showing the mechanical properties of polyester original cloth, polyester fabrics obtained in Example 1 and Comparative Example 1;

Figure 4 is a graph showing the test results of K/S after dyeing the polyester fabrics obtained in Example 1 and Comparative Example 1;

Figure 5 is a graph showing K/S test results after dyeing the polyester fabrics obtained in Example 1 and Comparative Example 4.

Detailed ways

The technical solution of the present invention will be explained below with reference to the embodiments of the present invention.

The raw material of the fabric polyester cloth used in the embodiments and comparative examples of the present invention is: 400T semi-dull polyester filament plain weave fabric.

Test methods involved in the present invention:

1. Test method for water contact angle of fabrics

Equilibrate the polyester fabric to be tested for 24 hours at a temperature of 25±1°C and a relative humidity of 65±2%. Cut samples at 3 different positions and paste them on a glass slide. Use a DSA 25 contact angle measuring instrument for testing. Water is the test solution, the volume of the test drop is 10 μL, and the distance between the drop needle and the surface of the polyester fabric is 10 mm. Measure the contact angle and take photos for storage. Each parallel sample is measured three times and the average value is taken.

2. Mechanical property testing of polyester fabrics

The HD026NS-200 multifunctional electronic fabric strength meter was used to conduct tensile and fracture tests on the polyester fabric to be tested. The test distance was 100mm and the tensile speed was 100mm/min.

3. K/S value test of polyester fabric:

Prepare the dye solution according to the liquor ratio of 1:100 and the methylene blue dye concentration of 0.5% owf, add the fabric, and react in a constant temperature shaker at 60°C and 150 rpm for 2 hours. After the reaction is completed, wash with deionized water and dry at room temperature.

A Datacolor 650 computer color matching instrument (Datacolor Company, USA) was used to conduct 10° observations under D65 light, and the K/S curves of pure fabrics and treated fabrics were drawn. The color rendering index of each fabric sample was tested 5 times, and the average value was taken as the final result. The effect of DES ultrasonic pretreatment on the dyeing properties of polyester fabrics was analyzed.

4. Hydrolyzate release test

Use deionized water to prepare TPA solutions with concentrations of 0 mg/L, 2.5 mg/L, 5 mg/L, 10 mg/L, 20 mg/L, and 40 mg/L. Use 0.1 mol/L NaOH solution to mix the above TPA solutions with different concentrations. Adjust the pH to 8.0, use deionized water as a reference, and measure the absorbance value of the above TPA solution with a double-beam UV spectrophotometer at 240 nm. Draw a standard curve with the absorbance and TPA standard solution concentration as the ordinate and abscissa respectively. After measurement, the present invention obtains the standard curve Y=0.00781X+0.00306, R ² =0.9994.

Centrifuge the reaction residue after enzyme inactivation, take the supernatant, and use a double-beam UV spectrophotometer to measure the absorbance of the cutinase-treated polyester reaction solution at a wavelength of 240 nm. Each group is tested three times. The obtained absorbance value was brought into the standard curve to obtain the TPA concentration.

5. Characterization of fabric appearance morphology

Before the test, the sample was sprayed with gold, and the changes in the surface morphology of the polyester fiber were observed using a SU1510 scanning electron microscope. The accelerating voltage during the electron microscope scanning test is 5.0kV, and the magnification is 2000 times.

Example 1

A method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzyme, including the following steps:

(1) Refining treatment of polyester fabric

Add 5g/L soap flakes and 4g/L sodium carbonate according to the liquor ratio of 1:30 to prepare a refining liquid. Add polyester cloth and process it at 98°C for 30 minutes. Wash with water and dry at 80°C. Finally, place the polyester fabric at a constant temperature. Equilibrate in a wet box (25±1℃, 65±2%) for 24h to obtain the refined polyester fabric;

(2) Preparation of DES

Add choline chloride and urea hydrogen bond donor and hydrogen bond acceptor into the beaker in molar ratio, stir and dissolve at 80°C until clear and transparent, and obtain DES solution;

The specific molar ratio is: choline chloride (ChCl): ethylene glycol (EG) = 1:2; choline chloride: glycerol (Gly) = 1:2;

Choline chloride: urea (U) = 1:2; Choline chloride: sorbitol (Sor) = 1:1; Choline chloride: xylitol (Sor) = 1:1;

Choline chloride: glycerol: urea = 1:1:1; Choline chloride: urea: ethylene glycol = 1:1:1;

Choline chloride:glycerol:ethylene glycol=1:1:1;

(3)DES ultrasonic pretreatment:

Dip the polyester fabric refined in step (1) into the choline chloride-urea ChCl-U deep eutectic solvent at a bath ratio of 1:40, ultrasonicate at 50°C for 30 minutes at 1000W, and rinse with deionized water after the treatment. Clean, dry at 60°C to constant weight, and place in a constant temperature and humidity box (21±1°C, 65±2%) to balance for 24 hours;

(4) Enzyme hydrolysis:

According to the bath ratio of 1:40, put the polyester fabric balanced in step (3) into 5mmol/L pH 8 Tris-HCl buffer, and then add Humicola insolens cutinase enzyme solution. The enzyme concentration is 100U/m L. React in a constant temperature shaker at 60°C and 150rpm for 24 hours. After the reaction, the polyester fabric is washed with deionized water, dried at 60°C to constant weight, and placed in a constant temperature and humidity box (21±1°C, 65±2%). Equilibrate for 24 hours and that's it.

Comparative example 1

The only difference from Example 1 is that steps (2) and (3) are omitted, and the polyester fabric after the refining treatment in step (1) is directly subjected to enzymatic hydrolysis. Other parameters and conditions are the same as in Example 1.

Comparative example 2

The only difference from Example 1 is that step (2) is omitted, and the choline chloride-urea ChCl-U deep eutectic solvent in step (3) is replaced with 5 mmol/L Tris-HCl buffer of pH 8, Other parameters and conditions are the same as Example 1.

Comparative example 3

The only difference from Example 1 is that the ultrasonic treatment in step (3) was changed to 150 rpm shaker treatment for 2 hours, and other parameters and conditions were the same as Example 1.

Performance Measurement

1. Conduct performance tests on the modified polyester fabrics obtained in Example 1 and Comparative Examples 1 to 3. The test results are as follows:

Table 1. Release results of enzymatic hydrolyzate of modified polyester fabric obtained in Example 1 and Comparative Examples 1 to 3

As can be seen from Table 1, pretreatment is helpful for subsequent enzymatic hydrolysis of polyester, among which DES + ultrasonic pretreatment has the best effect; DES itself has a large viscosity, and the introduction of ultrasound helps DES contact the substrate and improves the pretreatment effect. Compared with enzymatic hydrolysis without pretreatment, the release amount of hydrolyzate increased by 148.45%.

2. Conduct performance tests on the modified polyester fabrics obtained in Example 1 and Comparative Example 1

The contact angle test results are shown in Figure 1. In Figure 1 (a) is Comparative Example 1 and (b) is Example 1. It can be seen from Figure 1 that the contact angle of the polyester fabric enzymatically hydrolyzed without pretreatment is 89.8°. , the contact angle of the hydrophilic modified polyester fabric obtained in Example 1 is 86.5°. It can be seen that the contact angle is reduced by 3.7% after being treated by the method of the present invention, and the hydrophilic property is improved, realizing the transformation from hydrophobic polyester fabric to hydrophilic polyester fabric. Transformation of water polyester fabric.

Figure 2 is a scanning electron microscope image of the polyester fabric treated in Example 1 and Comparative Example 1. Figure (a) is Example 1 and Figure (b) Comparative Example 1. It can be seen from the figure that after pretreatment in Figure (a) The surface of the enzymatically hydrolyzed fiber is rough; while the surface of the enzymatically hydrolyzed fiber in Figure (b) is relatively smooth and is only slightly etched. This may be due to the hydrogen bonding in DES attacking the polyester ester bond in conjunction with the ultrasonic energy impact etching the polyester surface. This increases the specific surface area of polyester, increases the action sites of enzymes, and improves the efficiency of enzyme-catalyzed hydrolysis reactions.

Figure 3 is a comparison of the breaking strength and breaking elongation of the original fabric, the polyester fabric obtained in Example 1 and Comparative Example 1. It can be seen from Figure 3 that the breaking strength of the polyester fabric after enzymatic hydrolysis is lower than that of the original fabric, but it can still maintain a breaking strength of more than 300N. Even if pretreatment is added, it will not have a big impact on the strength of the fabric; pretreatment The elongation at break of the fabric obtained by post-enzyme hydrolysis is slightly lower than that of the fabric enzymatically hydrolyzed from the original cloth, but it can still maintain an elongation at break of more than 28%, indicating that the enzyme hydrolysis is gentle and does not have much impact on the mechanical properties of the fabric. Physical The mechanical properties are equivalent to those of other alkali treatment methods, and the functional layer has better effects.

Figure 4 shows the K/S test results after dyeing the polyester fabric obtained in Example 1 and Comparative Example 1. Cutinase can hydrolyze the ester bonds in the polyester molecular chain into -COOH groups and -OH groups. Methylene blue is a vital dye and a basic dye that can be combined with carboxyl groups, so it can be used to test the hydrolysis effect. . It can be seen from the test results that the K/S value of the dyed enzymatically hydrolyzed polyester fabric increases significantly at the wavelength of 550-650nm, indicating that the polyester cutinase hydrolyzes the ester bond and increases the -COOH group. The K/S value of the fabric obtained by DES pretreatment is obviously It is larger than that of fabric without pretreatment, indicating that DES pretreatment helps cutinase hydrolyze polyester.

Example 2 Effects of different ultrasonic pretreatment powers on the release of enzymatic hydrolyzate products

The only difference from Example 1 is that the ultrasonic power in step (3) of Example 1 is adjusted to 200W, 400W, 600W, 800W, 1000W, and the other parameters and conditions are the same as Example 1; the obtained hydrophilic modified A performance test was conducted on a durable polyester fabric. The test results are as follows:

Table 2. Product release results with different ultrasonic powers in Example 2

Ultrasonic power (W) 200 400 600 800 1000 Product release amount (mg/L) 46.07 47.30 47.99 48.38 54.15

It can be seen from Table 2 that as the ultrasonic power increases, the subsequent release of hydrolyzate increases; the preferred ultrasonic power is 1000W.

Example 3 Effects of different solvent types on product release

The only difference from Example 1 is that the ultrasonic solvents in step (3) of Example 1 are adjusted to ChCl-EG, ChCl-Gly, ChCl-U-Gly, ChCl-U-EG, ChCl-EG-Gly, ChCl-Sor, ChCl-Xyl, and other parameters and conditions are the same as Example 1; the obtained hydrophilic modified polyester fabric was tested for performance, and the test results are as follows:

Table 3. Product release results of different solvent types in Example 3

Solvent type Product release amount (mg/L) ChCl-EG 49.14 ChCl-Gly 48.76 ChCl-U (Example 1) 54.15 ChCl-U-Gly 34.55 ChCl-U-EG 33.78 ChCl-EG-Gly 33.01 ChCl-Sor 42.23 ChCl-Xyl 52.60

It can be seen from Table 3 that the pretreatment effect of binary DES solvent is higher than that of ternary DES, among which the DES pretreatment effect composed of choline chloride and urea has the best effect.

Comparative example 4

The only difference from Example 1 is that the ultrasonic solvent in step (3) of Example 1 is adjusted to choline chloride-oxalic acid (ChCl-OA), choline chloride-lactic acid (ChCl-LA), choline chloride Alkali-citric acid (ChCl-CA), other parameters and conditions are the same as Example 1; the obtained hydrophilic modified polyester fabric is subjected to performance testing, and the test results are as follows:

Table 4. Product release results of Comparative Example 4 and Example 1

Solvent type Product release amount (mg/L) ChCl-U (Example 1) 54.15 ChCl-OA 13.57 ChCl-LA 31.5 ChCl-CA 39.57

As can be seen from Table 4, the pretreatment effect of DES prepared by using acidic monomers is not as good as that of alcohol or amide monomers. It may be that the pH of DES prepared by acidic monomers is acidic, while the DES prepared by alcohols or amides is more alkaline. Polyester fabric itself is resistant to acid and alkali. The etching effect of polyester fabric treated with DES of alcohol or amide monomer is better than that of acid monomer, which provides more attachment points for enzymes, making it easier to use alcohol or amide monomer. The enzymatic hydrolysis effect of DES treatment of monomers is greater than that of acidic monomers.

Figure 5 shows the K/S test results after dyeing the polyester fabrics obtained in Example 1 and Comparative Example 4. It can be seen from the test results that the K/S value trend of the dyed enzymatically hydrolyzed polyester fabric is consistent with the product release amount. ChCl-U pretreatment helps cutinase hydrolyze ester bonds to produce more -COOH groups, so the K/S Significantly greater than fabrics pretreated with acidic monomer DES.

Example 4 Effect of different pretreatment temperatures on product release

The only difference from Example 1 is that the ultrasonic temperatures in step (3) of Example 1 are adjusted to 30°C, 40°C, 60°C, and 70°C respectively. Other parameters and conditions are the same as Example 1; the obtained Hydrophilic modified polyester fabric was tested for performance and the test results are as follows:

Table 5. Results of release amount of enzymatic hydrolyzate in Example 4

Ultrasonic temperature (℃) 30 40 50(Example 1) 60 70 Product release amount (mg/L) 38.77 43.00 54.15 52.63 49.53

It can be seen from Table 5 that as the temperature increases, the enzymatic hydrolysis yield first increases and then decreases. When the temperature is 50°C, the amount of hydrolyzate released reaches the maximum.

Example 5 Effects of different ultrasonic pretreatment times on the release of enzymatic hydrolyzate products

The only difference from Example 1 is that the ultrasonic times in step (3) of Example 1 are adjusted to 1, 2, 3, 4, 6, and 8 hours respectively, and other parameters and conditions are the same as those in Example 1. The obtained hydrophilic modified polyester fabric was tested for performance. The test results are as follows:

Table 6. Results of release amount of enzymatic hydrolyzate in Example 5

It can be seen from Table 6 that a short period of ultrasonic pretreatment can help increase the action sites of enzymes and promote enzyme hydrolysis, among which ultrasonic treatment for 30 minutes has the best effect. Long-term high-power ultrasonic treatment may rearrange the structure of the amorphous region in the polyester molecules, increase the crystallinity, and hinder enzyme promotion.

The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Those skilled in the art can make obvious improvements to the present invention based on existing common knowledge, which will also fall within the protection scope defined by the claims of the present invention.

Claims (10)

1. A method for hydrophilic modification of polyester using DES ultrasonic pretreatment combined with enzyme, characterized in that the method includes the following steps: (1) Preparation of DES solvent Add the hydrogen bond donor and hydrogen bond acceptor into the beaker, stir and dissolve until it is clear and transparent, and the DES solvent is obtained; the hydrogen bond donor is alcohol or amide monomer; the hydrogen bond acceptor is choline chloride and betaine , one or two of choline citrate; (2) Put the refined polyester fabric into the DES solvent prepared in step (1) for ultrasonic treatment. After the treatment, wash and dry; (3) Put the polyester fabric dried in step (2) into Tris-Hcl buffer, add Humicola insolens cutinase enzyme solution for hydrolysis reaction, after the reaction is completed, inactivate the reaction residue, wash and dry the fabric Just dry it. 2. The method according to claim 1, wherein the hydrogen bond donor is one or more of glycerol, ethylene glycol, urea, sorbitol, xylitol, glucose and triethanolamine. 3. The method according to claim 1, characterized in that the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor in step (1) is 1:1-2. 4. The method according to claim 1, characterized in that the bath ratio of the refined polyester fabric and DES solvent in step (2) is 1:40. 5. The method according to claim 1, characterized in that the ultrasonic treatment conditions in step (2) are 0.5-8 hours at 30-70°C and a power of 200-1000W. 6. The method according to claim 1, characterized in that the Humicola insolens cutinase in step (3) has an enzyme activity of 1000-2000 U/mL and an enzyme dosage of 100 U/mL. 7. The method according to claim 1, characterized in that the hydrolysis reaction bath ratio in step (3) is 1:40, the temperature is 60-65°C, and the time is 18-24 hours. 8. The method according to claim 1, characterized in that the ultrasonic treatment conditions in step (2) are reaction at 50°C and a power of 1000W for 30 minutes. 9. Hydrophilic polyester modified by the method of any one of claims 1 to 8. 10. Application of the hydrophilic polyester according to claim 9 in the textile field.