Method for hydrophilic modification of polyester by des ultrasonic pretreatment combined with enzyme

Abstract

The application discloses a method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzymes, and belongs to the technical field of surface modification. The polyester hydrophilic modification method is specifically as follows: after refining, polyester fabric is put into a DES solvent for ultrasonic treatment, and after the treatment, washing and drying are performed; the dried polyester fabric is put into a 5mmol / L Tris-Hcl buffer solution with pH 8, and Hic keratinase enzyme liquid is added for hydrolysis reaction; after the reaction, the reaction residue is inactivated, and the fabric is washed and dried; the hydrogen bond donor of the DES solvent is an alcohol or an amide monomer, and the hydrogen bond acceptor is one or two of choline chloride, betaine and dihydrocholine citrate; compared with a traditional chemical modification method, the method is environmentally friendly, has no pollution, has a small influence on mechanical properties, and is mild and efficient in modification effect.

Description

TECHNICAL FIELD

[0001] The application 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

[0002] Polyester (PET) is an important variety of synthetic fibers, which 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 and washable wearability. However, the polyester molecular chain contains a large number of ester groups, only two terminal alcohol hydroxyl groups, and no other polar groups, so that the hydrophilicity of pure polyester fabric is very poor, dyeing is difficult, and wearing is hot, which limits the use of polyester in many textile applications, such as sportswear, bedding and the like.

[0003] Due to the wide application of PET, the wettability of its fabric is an important topic of basic research and application research. In recent years, the surface hydrophilic modification methods of polyester fibers mainly include the following ways: surface oxidation method, surface coating method, surface grafting method, alkali reduction treatment, biological modification method such as enzyme modification and the like; but these modification methods still have technical defects, such as the alkali reduction finishing process consumes a large amount of alkali and water, a large amount of wastewater containing concentrated alkali and high oligomer content is discharged, and the environment is damaged; the hydrophilic agent coating has poor water resistance, and many chemicals are not easy to degrade; the ultraviolet grafting modification effect has timeliness and other problems. SUMMARY

[0004] In the prior art, the alkali hydrolysis method has a great influence on the mechanical properties of the fabric, and the wastewater containing a large amount of chemical substances pollutes the environment; the surface coating method has poor water resistance, and the coated chemical substances are not easy to degrade in the environment; the pure biological enzyme has the problem of poor modification effect on the hydrophilic modification of polyester.

[0005] In order to solve at least one of the above problems, the application uses a biodegradable solvent DES to ultrasonically pretreat the polyester fabric, and then uses cutinase for enzyme hydrolysis to improve the hydrophilicity of the polyester fabric.

[0006] The first object of the application is to provide a method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzyme, which comprises the following steps:

[0007] (1) preparing a DES solvent

[0008] The hydrogen bond donor and the hydrogen bond acceptor are added to a beaker, stirred and dissolved to be clear and transparent, and the DES solvent is obtained; wherein the hydrogen bond donor is an alcohol or an amide monomer; the hydrogen bond acceptor is one or two of choline chloride, betaine and dihydrocholine citrate;

[0009] (2) Put the refined polyester fabric into the DES solvent prepared in step (1) for ultrasonic treatment. After the treatment, wash and dry the fabric;

[0010] (3) Put the polyester fabric dried in step (2) into Tris-Hcl buffer solution, and add Humicolainsolens cutinase enzyme solution for hydrolysis reaction. After the reaction, inactivate the reaction residue, wash and dry the fabric, and the process is completed.

[0011] In an embodiment, the hydrogen bond donor in step (1) is one or more of glycerol, ethylene glycol, urea, sorbitol, xylitol, glucose and triethanolamine.

[0012] In an embodiment, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor in step (1) is 1:1-2.

[0013] In an embodiment, the temperature during the stirring process for preparing the DES solvent in step (1) is 80-100℃.

[0014] In an embodiment, the refined polyester fabric in step (2) refers to the following process: put the polyester fabric in deionized water with a bath ratio of 1:40-60, add 3-6 g / L of soap chips and 3-6 g / L of anhydrous sodium carbonate, and refine in a constant temperature water bath at 80-100℃ for 30 min-1 h. Then, wash the fabric with deionized water, dry in an oven at 80-100℃ until the weight is constant, and equilibrate at a temperature and humidity of 25±1℃ and 65±2% for 24 h. Further preferably, the bath ratio is 1:30, 5 g / L of soap chips and 4 g / L of anhydrous sodium carbonate are added, and the fabric is refined at 98℃ for 30 min. The drying temperature is 80℃.

[0015] In an embodiment, the bath ratio of the refined polyester fabric to the DES solvent in step (2) is 1:40.

[0016] In an embodiment, the ultrasonic treatment in step (2) is carried out at 30-70℃ and a power of 200-1000 W for 0.5-8 h. Further preferably, the treatment is carried out at 50℃ and a power of 1000 W for 30 min.

[0017] In an embodiment, the washing in step (2) refers to washing the fabric with deionized water.

[0018] In an embodiment, the drying temperature in step (2) is 60-70℃.

[0019] In an embodiment, the Humicolainsolens cutinase in step (3) has an enzyme activity of 1000-2000 U / mL, and the enzyme dosage is 100 U / mL.

[0020] In an embodiment, the Tris-HCl buffer solution in step (3) has a pH of 7-9, preferably 8, and a concentration of 5 mmol / L.

[0021] In an embodiment, the hydrolysis reaction in step (3) has a bath ratio of 1:40, a temperature of 60-65°C, and a time of 18-24 h.

[0022] In an embodiment, the inactivation in step (3) is performed by heating the reaction residue in a constant-temperature water bath at 100°C for 30 min.

[0023] In an embodiment, the washing in step (3) refers to washing the fabric with deionized water.

[0024] In an embodiment, the drying in step (3) has a temperature of 60-70°C.

[0025] A second object of the present application is to provide a hydrophilic polyester obtained by the above modification method.

[0026] A third object of the present application is to provide an application of the hydrophilic polyester fabric obtained by the above method in the field of textiles.

[0027] In an embodiment, the field of textiles includes household and industrial textile fields.

[0028] Advantages of the present application:

[0029] (1) The present application uses deep eutectic solvent (DES) for pretreatment of polyester fabric, and the solvent is simple to prepare, low in cost, biodegradable, and recyclable, and the modification conditions are simple and environmentally friendly.

[0030] (2) The present application uses Hic cutinase to catalyze the hydrolysis of the ester bonds on the surface of the polyester fabric, so that hydroxyl and carboxyl groups are generated on the surface of the polyester, and the polyester is hydrophilic and modified without changing its own performance;

[0031] (3) The present application pretreats the polyester fabric with DES, and the release amount of the product is obviously improved compared to the product without pretreatment, and the mechanical property is less affected compared to traditional chemical modification methods.

[0032] (4) The present application pretreats the polyester fabric with DES, and the release amount of the enzymatic hydrolysis product is increased by 148.45% compared to the product without pretreatment; and the hydrophilic angle of the enzymatic hydrolysis after DES pretreatment is decreased from 89.8° to 86.5°. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1The test result figure of the contact angle of the hydrophilic modified polyester fabric obtained after the pretreatment enzymolysis of Example 1 and the polyester fabric after the enzymolysis without pretreatment of Comparative Example 1; (a) is Comparative Example 1; (b) is Example 1;

[0034] Figure 2 The scanning electron microscope figure of the obtained fabric of Example 1 and Comparative Example 1; (a) is Example 1; (b) is Comparative Example 1;

[0035] Figure 3 The mechanical property figure of the polyester fabric of the original fabric, Example 1 and Comparative Example 1;

[0036] Figure 4 The test result figure of K / S of the polyester fabric of Example 1 and Comparative Example 1 after dyeing;

[0037] Figure 5 The test result figure of K / S of the polyester fabric of Example 1 and Comparative Example 1 after dyeing. DETAILED DESCRIPTION

[0038] The technical solutions of the present application are explained and described below in combination with the embodiments of the present application.

[0039] The fabric polyester fabric raw material adopted in the embodiments and comparative examples of the present application is: 400T semi-dull polyester filament plain fabric.

[0040] The test method involved in the present application:

[0041] 1. The water contact angle test method of the fabric

[0042] The polyester fabric to be tested is equilibrated under the condition of temperature 25±1℃ and relative humidity 65±2% for 24h, and samples at 3 different positions are cut and pasted on a glass slide, a DSA 25 contact angle measuring instrument is used for testing, deionized water is used as the test solution, the volume of the test drop is 10μL, the distance between the drop needle and the surface of the polyester fabric is 10mm, the contact angle is measured and photographed, each parallel sample is measured 3 times, and the average value is taken.

[0043] 2. The mechanical property test of the polyester fabric

[0044] The HD026NS-200 multifunctional electronic fabric strength tester is used for the tensile fracture test of the polyester fabric to be tested, the gauge length is 100mm, and the tensile speed is 100mm / min.

[0045] 3. The K / S value test of the polyester fabric:

[0046] The dyeing solution was prepared according to a bath ratio of 1:100 and a methylene blue dye concentration of 0.5% owf, and then the fabric was added and reacted at 60°C for 2h on a constant temperature shaker at 150rpm. After the reaction, the sample was washed with deionized water and dried at room temperature.

[0047] The K / S curves of the pure fabric and the treated fabric were drawn using a Datacolor 650 computer color matching instrument (Datacolor Company, USA) under D65 light with 10° observation. The color rendering index test of each fabric sample was performed 5 times, and the average value was taken as the final result. The effect of DES ultrasonic pretreatment on the dyeing performance of polyester fabric was analyzed.

[0048] 4. Hydrolyzate release amount test

[0049] A TPA solution with concentrations of 0mg / L, 2.5mg / L, 5mg / L, 10mg / L, 20mg / L and 40mg / L was prepared with deionized water, and the pH of the above TPA solutions with different concentrations was adjusted to 8.0 with a 0.1mol / L NaOH solution. The absorbance values of the above TPA solutions were measured at 240nm with a double-beam ultraviolet spectrophotometer with deionized water as a reference. The standard curve was drawn with absorbance and TPA standard solution concentration as the vertical and horizontal coordinates, respectively. The standard curve Y=0.00781X+0.00306, R 2 =0.9994 was obtained by measurement.

[0050] The reaction residue after enzyme inactivation was centrifuged, and the supernatant was taken. The absorbance of the reaction solution of the keratinase-treated polyester was measured at 240nm with a double-beam ultraviolet spectrophotometer, and each group was tested 3 times. The obtained absorbance value was brought into the standard curve to obtain the TPA concentration.

[0051] 5. Fabric apparent morphology characterization

[0052] Before testing, the sample was sprayed with gold, and the change in the surface morphology of the polyester fiber was observed using a SU1510 scanning electron microscope. The accelerating voltage during the electron microscope scanning test was 5.0kV, and the magnification was 2000 times.

[0053] Example 1

[0054] A method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzymes, comprising the following steps:

[0055] (1) Refining treatment of polyester fabric

[0056] Refining solution was prepared by adding 5 g / L soap flake and 4 g / L sodium carbonate according to bath ratio 1:30, and then polyester fabric was added and treated at 98℃ for 30 min; then it was washed with water, dried at 80℃, and finally placed in a constant temperature and humidity box (25±1℃, 65±2%) for 24 h to obtain the refined polyester fabric;

[0057] (2) Preparation of DES

[0058] Choline chloride and urea hydrogen bond donor and hydrogen bond acceptor were added into a beaker according to the molar ratio, and stirred and dissolved at 80℃ until clear and transparent, to obtain a DES solution;

[0059] The specific molar ratio was: choline chloride (ChCl): ethylene glycol (EG) = 1:2; choline chloride: glycerol (Gly) = 1:2;

[0060] Choline chloride: urea (U) = 1:2; choline chloride: sorbitol (Sor) = 1:1; choline chloride: xylitol (Sor) = 1:1;

[0061] Choline chloride: glycerol: urea = 1:1:1; choline chloride: urea: ethylene glycol = 1:1:1;

[0062] Choline chloride: glycerol: ethylene glycol = 1:1:1;

[0063] (3) DES ultrasonic pretreatment:

[0064] The polyester fabric refined in step (1) was immersed in a choline chloride-urea ChCl-U deep eutectic solvent according to bath ratio 1:40, and treated with 1000W ultrasonic at 50℃ for 30 min; then it was washed with deionized water, dried at 60℃ to constant weight, and placed in a constant temperature and humidity box (21±1℃, 65±2%) for 24 h.

[0065] (4) Enzymatic hydrolysis:

[0066] The polyester fabric equilibrated in step (3) was placed in 5 mmol / L Tris-HCl buffer solution at pH 8 according to bath ratio 1:40, and then humicola insolens cutinase solution was added, with an enzyme concentration of 100 U / m L; the reaction was carried out at 60℃ in a constant temperature shaker at 150 rpm for 24 h; after the reaction, the polyester fabric was washed with deionized water, dried at 60℃ to constant weight, and placed in a constant temperature and humidity box (21±1℃, 65±2%) for 24 h.

[0067] Comparative Example 1

[0068] The difference from Example 1 was that steps (2) and (3) were omitted, and the polyester fabric after refining treatment in step (1) was directly subjected to enzymatic hydrolysis, and other parameters and conditions were the same as those in Example 1.

[0069] Comparative Example 2

[0070] The only difference from Example 1 is that step (2) is omitted and the eutectic solvent of choline chloride-urea (ChCl-U) in step (3) is replaced with 5 mmol / L pH 8 Tris-HCl buffer solution. All other parameters and conditions are the same as in Example 1.

[0071] Comparative Example 3

[0072] The only difference from Example 1 is that the ultrasonic treatment in step (3) is replaced with a shaking table treatment at 150 rpm for 2 hours. All other parameters and conditions are the same as in Example 1.

[0073] Performance testing

[0074] 1. The modified polyester fabrics obtained in Example 1 and Comparative Examples 1-3 were subjected to performance tests, and the test results are as follows:

[0075] Table 1. Results of enzyme hydrolysis product release from modified polyester fabrics obtained in Example 1 and Comparative Examples 1-3

[0076]

[0077] As can be seen from Table 1, all pretreatments are helpful for subsequent enzymatic hydrolysis of polyester, with DES + ultrasonic pretreatment showing the best effect. DES itself has a high viscosity, and the introduction of ultrasound helps DES to contact the substrate, improving the pretreatment effect. Compared with enzymatic hydrolysis without pretreatment, the release of hydrolysis products increased by 148.45%.

[0078] 2. Performance tests were conducted on the modified polyester fabrics obtained in Example 1 and Comparative Example 1.

[0079] Contact angle test results as follows Figure 1 As shown, Figure 1 (a) is Comparative Example 1, and (b) is Example 1; from Figure 1 It can be seen that the contact angle of the untreated enzymatically hydrolyzed polyester fabric is 89.8°, and 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 treatment by the method of the present invention, the hydrophilicity is improved, and the transformation from hydrophobic polyester fabric to hydrophilic polyester fabric is realized.

[0080] Figure 2The scanning electron microscope images of the treated polyester fabric of Example 1 and Comparative Example 1, wherein Figure (a) is Example 1 and Figure (b) is Comparative Example 1; it can be seen from the images that the fiber surface after pretreatment and enzymatic hydrolysis in Figure (a) is rough; while the fiber surface after enzymatic hydrolysis of the original fabric in Figure (b) is relatively smooth, only slightly etched, which is likely due to the hydrogen bond attack on the ester bond of the polyester in DES, combined with the ultrasonic energy impact to etch the surface of the polyester, so that the specific surface area of the polyester increases, the action site of the enzyme increases, and the efficiency of the enzyme catalytic hydrolysis reaction is improved.

[0081] Figure 3 The breaking strength and elongation at break of the polyester fabric obtained from the original fabric, Example 1 and Comparative Example 1 are compared. From Figure 3 It can be seen that the breaking strength of the polyester fabric after enzymatic hydrolysis is reduced compared with the original fabric, but still maintains a breaking strength of more than 300 N, and even if the pretreatment is increased, the effect on the fabric strength is not great; the elongation at break of the fabric after pretreatment and enzymatic hydrolysis is slightly lower than that of the fabric after enzymatic hydrolysis of the original fabric, but still maintains an elongation at break of more than 28%, indicating that the enzymatic hydrolysis is mild and has little effect on the mechanical properties of the fabric, the physical and mechanical properties are comparable to other alkali treatment methods, and the functional layer has better effects.

[0082] Figure 4 The K / S test results of the polyester fabric obtained from Example 1 and Comparative Example 1 after dyeing. Cutinase can hydrolyze the ester bond in the polyester molecular chain into -COOH and -OH groups, methylene blue is a vital dye, which is a basic dye and can combine 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 enzymatically hydrolyzed polyester fabric after dyeing increases significantly at a wavelength of 550-650 nm, indicating that the ester bond is hydrolyzed by cutinase to increase the -COOH group, and the K / S of the fabric pretreated by DES is significantly greater than that of the fabric without pretreatment, indicating that DES pretreatment helps cutinase to hydrolyze polyester.

[0083] Effect of different ultrasonic pretreatment powers on the release amount of enzymatic hydrolysis products in Example 2

[0084] The difference between Example 1 is that the ultrasonic power in step (3) of Example 1 is adjusted to 200 W, 400 W, 600 W, 800 W and 1000 W, and the rest of the parameters and conditions are the same as in Example 1; the hydrophilic modified polyester fabric is tested for performance, and the test results are as follows:

[0085] Table 2. Product release amount results of different ultrasonic powers in Example 2

[0086] Ultrasonic power (W) 200 400 600 800 1000 Product release (mg / L) 46.07 47.30 47.99 48.38 54.15

[0087] It can be seen from Table 2 that as the ultrasonic power increases, the subsequent hydrolysis product release amount increases; the preferred ultrasonic power is 1000 W.

[0088] Example 3: Effect of different solvent types on product release amount

[0089] The only difference from Example 1 is that the ultrasonic solvent in step (3) of Example 1 was adjusted to be ChCl-EG, ChCl-Gly, ChCl-U-Gly, ChCl-U-EG, ChCl-EG-Gly, ChCl-Sor, and ChCl-Xyl, respectively. All other parameters and conditions were the same as in Example 1. The hydrophilic modified polyester fabric was subjected to performance testing, and the test results are as follows:

[0090] Table 3. Results of product release for different solvent types in Example 3

[0091] Solvent type Product release (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

[0092] As can be seen from Table 3, the effect of pretreatment with binary DES solvent is higher than that of ternary DES, and the pretreatment effect of DES composed of choline chloride and urea is the best.

[0093] Comparative Example 4

[0094] The only difference from Example 1 is that the ultrasonic solvent in step (3) of Example 1 was adjusted to choline chloride-oxalic acid (ChCl-OA), choline chloride-lactic acid (ChCl-LA), or choline chloride-citric acid (ChCl-CA). Other parameters and conditions were the same as in Example 1. The hydrophilic modified polyester fabric was subjected to performance testing, and the test results are as follows:

[0095] Table 4. Results of product release in Comparative Example 4 and Example 1

[0096] Solvent type Product release (mg / L) ChCl-U (Example 1) 54.15 ChCl-OA 13.57 ChCl-LA 31.5 ChCl-CA 39.57

[0097] As can be seen from Table 4, the pretreatment effect of DES prepared with acidic monomers is not as good as that of DES prepared with alcohol or amide monomers. This may be because the pH of DES prepared with acidic monomers is acidic, while that prepared with alcohol or amide monomers is alkaline. Due to the nature of polyester fabrics being acid-resistant but not alkali-resistant, the etching effect of polyester fabrics treated with DES of alcohol or amide monomers is better than that of acidic monomers, providing more attachment sites for enzymes. Therefore, the enzymatic hydrolysis effect of DES treated with alcohol or amide monomers is greater than that of acidic monomers.

[0098] Figure 5 The results show the K / S ratio of the polyester fabrics obtained in Example 1 and Comparative Example 4 after dyeing. The test results indicate that the K / S value trend of the enzymatically hydrolyzed polyester fabrics after dyeing is consistent with the product release amount. ChCl-U pretreatment helps keratinase hydrolyze ester bonds to generate more -COOH groups, therefore the K / S ratio is significantly higher than that of fabrics pretreated with the acidic monomer DES.

[0099] Effect of different pretreatment temperature on product release amount

[0100] The difference from Example 1 is that the ultrasonic temperature in step (3) of Example 1 is adjusted to 30℃, 40℃, 60℃, 70℃ respectively, and other parameters and conditions are the same as those of Example 1. The hydrophilic modified polyester fabric obtained is subjected to performance testing, and the test results are as follows:

[0101] Table 5. Enzymatic product release amount results of Example 4

[0102] Ultrasonic temperature (°C) 30 40 50 (Example 1) 60 70 Product release (mg / L) 38.77 43.00 54.15 52.63 49.53

[0103] As can be seen from Table 5, with the increase of temperature, the enzymolysis amount shows a trend of first increasing and then decreasing, and when the temperature is 50℃, the hydrolysis product release amount reaches the maximum.

[0104] Effect of different ultrasonic pretreatment time on enzymatic product release amount

[0105] The difference from Example 1 is that the ultrasonic time in step (3) of Example 1 is adjusted to 1, 2, 3, 4, 6, 8h respectively, and other parameters and conditions are the same as those of Example 1. The hydrophilic modified polyester fabric obtained is subjected to performance testing, and the test results are as follows:

[0106] Table 6. Enzymatic product release amount results of Example 5

[0107]

[0108] As can be seen from Table 6, short-time ultrasonic pretreatment helps to increase the action site of the enzyme and promote enzyme hydrolysis, and the effect is best when the ultrasonic treatment time is 30min. Long-time high-power ultrasonic treatment may rearrange the amorphous structure in the polyester molecule and increase the crystallinity, thereby hindering the enzyme promotion.

[0109] The above examples provided are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the present application in combination with the existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for hydrophilic modification of polyester by DES ultrasonic pretreatment combined with enzyme, characterized in that, The method comprises the following steps: (1) Preparation of DES solvent The hydrogen bond donor and hydrogen bond acceptor are added into a beaker, stirred and dissolved until clear and transparent, to obtain the DES solvent; wherein the hydrogen bond acceptor is choline chloride; and the hydrogen bond donor is urea; (2) The refined polyester fabric is placed into the DES solvent prepared in step (1) for ultrasonic treatment, and after the treatment, washing and drying are performed; the ultrasonic treatment conditions are 50℃, power 1000W, and reaction time 30min; (3) The polyester fabric dried in step (2) is placed into Tris-Hcl buffer solution, and Humicola insolens cutinase enzyme solution is added for hydrolysis reaction, after the reaction, the reaction residue is inactivated, and the fabric is washed and dried.

2. The method of claim 1, wherein, In step (1), the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-2.

3. The method of claim 1, wherein, In step (2), the bath ratio of the refined polyester fabric to the DES solvent is 1:

40.

4. The method of claim 1, wherein, In step (3), the Humicola insolens cutinase has an enzyme activity of 1000-2000U / mL, and the enzyme dosage is 100U / mL.

5. The method of claim 1, wherein, In step (3), the bath ratio of the hydrolysis reaction is 1:40, the temperature is 60-65℃, and the time is 18-24h.

6. Hydrophilic polyester obtained by modification according to the method in any one of claims 1-5.

7. Application of the hydrophilic polyester in claim 6 in the field of textiles.

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