Degumming-free silk blank softening method and application

Abstract

The invention relates to a softening method and application of a degumming-free silk blank, and belongs to the technical field of silk processing. Softening treatment is completed at the low temperature of 40-50 DEG C through a chitosan composite coating; the method specifically comprises the steps of chitosan acid dissolution and glycerin compounding, blank ultrasonic treatment and transglutaminase activation, plastifying system coating, softener treatment and low-temperature curing. The degumming rate of the processed silk blank is only 0.02%-0.05%, the softness is improved by 88%-95.8%, the natural functions of moisturizing, antibiosis and the like of sericin are reserved, and the problems that the blank is rough and hard in hand feeling, chemical residues exist, and the compatibility of the dyeing and finishing process is poor are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of silk processing, in particular to a softening method for degumming-free silk blank and application. BACKGROUND

[0002] As a natural protein fiber, silk has irreplaceability in the fields of high-end fashion, medical dressings and beauty textiles due to excellent skin-friendliness, gloss and biocompatibility. In the traditional silk processing, the degumming process needs to remove sericin protein on the surface of silk fibers in a high-temperature 90-100 DEG C and strong-alkali pH 9-11 environment, which not only causes the strength of silk fibers to decrease and the gloss to deteriorate, but also has problems of high energy consumption and high water consumption.

[0003] With the popularization of the concept of green manufacturing, the degumming-free process has become a research hotspot because it can retain the natural functions of sericin protein such as moisturizing, antibacterial and antioxidant. Sericin protein contains various amino acids and has biological compatibility and skin-friendliness, which has unique advantages in medical and beauty textiles. However, the degumming-free silk blank is rough and hard due to the adhesion of sericin protein, and the irregular surface morphology of the fibers hinders the uniform penetration and adsorption of dyes in the dyeing and finishing process, which is easy to produce defects such as color spots and color spots. At the same time, the traditional softening technology mostly relies on chemical agents, which may leave harmful substances or destroy the activity of sericin protein, and it is difficult to meet the requirements of high-end products on comfort, environmental protection and processing compatibility. In addition, sericin protein is easy to denature under wet heat conditions, and if the temperature control is not proper in the traditional degumming and softening process, the stability of the fabric performance may be affected.

[0004] Therefore, it is necessary to develop a degumming-free silk blank softening method which has efficient softening capacity, environmental safety and compatibility with subsequent processing technology. SUMMARY

[0005] The application aims to provide a degumming-free silk blank softening method and application, which solves the problems of rough and hard degumming-free silk blank, high chemical residue risk of traditional degumming and softening technology, poor compatibility of subsequent dyeing and finishing process and easy denaturation of sericin protein due to high temperature.

[0006] In one aspect, the application provides a degumming-free silk blank softening method, which adopts the following technical scheme:

[0007] A degumming-free silk blank softening method, comprising the following steps:

[0008] S1, taking chitosan powder, preparing a chitosan solution with a concentration of 0.5-1.5% at 30-40 DEG C, adding food-grade citric acid, adjusting the pH to 4.5-5.5, adding glycerol, and heating and stirring to obtain a plasticizing composite system;

[0009] S2, the silk fabric is immersed in ddH2O at 40℃ for ultrasonic treatment, and then taken out and immersed in a transglutaminase solution with a concentration of 0.3-0.5%, and the silk fabric is heated and stirred;

[0010] S3, the silk fabric treated in step S2 is immersed in the plasticized composite system prepared in step S1, and then taken out and immersed in a softener solution prepared in advance, and then taken out and washed with water and dried.

[0011] Preferably, the degree of deacetylation of the chitosan powder in step S1 is ≥85%, and the molecular weight is 10-50kDa.

[0012] Preferably, the amount of glycerol added in step S1 is 3-5% of the mass of the chitosan powder in step S1.

[0013] The purity of the glycerol is ≥99%.

[0014] Preferably, the temperature in step S1 is raised to 50℃, the stirring rate is 200-300rpm, and the stirring time is 30min.

[0015] Preferably, the frequency of ultrasonic treatment in step S2 is 40kHz, and the ultrasonic treatment time is 20min.

[0016] Preferably, the temperature of the transglutaminase solution in step S2 is 40-50℃.

[0017] The silk fabric is immersed in the transglutaminase solution for 20min, and the silk fabric is turned over every 5min.

[0018] Preferably, in step S3, during the process of immersing the silk fabric in the plasticized composite system, the temperature of the plasticized composite system is 25-30℃, and the immersion time is 30min, and the silk fabric is turned over every 5min.

[0019] Preferably, in step S3, during the process of immersing the silk fabric in the softener solution, the bath ratio is 1:(30-40), the temperature of the softener solution is 45℃, and the immersion time is 1h.

[0020] Preferably, in step S3, the silk fabric is pre-dried at 40℃ for 10min, and then dried at 50℃ until dry.

[0021] In another aspect, the present application also provides an application of the softening method of the above-mentioned delustring silk fabric, which adopts the following technical scheme:

[0022] An application of the softening method of the delustring silk fabric in raw silk, silk textiles and blended products.

[0023] In summary, the present application includes the following beneficial technical effects:

[0024] 1、The chitosan powder in the present application forms a uniform coating with glycerol by acidic dissolution at pH 4.5-5.5, adsorbs on the fiber surface to form a lubricating film, improves the rough and hard problem of the non-debound raw material, and improves the softness and smoothness; the transglutaminase solution activates the silk raw material, promotes the crosslinking of chitosan molecules and sericin, improves the porous structure of the fiber surface, improves the uniformity of dye adsorption in the subsequent dyeing process, and reduces the risk of color spots and color spots.

[0025] 2、The present application processes at a temperature ≤50℃ throughout, avoids denaturation of sericin under humid heat conditions, retains its natural moisture retention, antibacterial, antioxidant and other functions, and is suitable for medical and beauty textiles; and low-temperature curing at 40℃ pre-drying and 50℃ final drying fixes the coating, ensuring long-lasting softening effect.

[0026] 3、The softening method of the non-debound silk raw material of the present application improves the softness of the silk raw material by 88-95.8%. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0028] Preparation Example

[0029] Preparation Example 1

[0030] The preparation method of the softener solution specifically includes the following steps:

[0031] 1) Add 10% hydrophilic block silicone oil to the reaction container, stir and heat to 55℃, while adding 4% polyoxyethylene stearate, continue to stir until the mixed solution is uniform and transparent, forming a stable pre-emulsified silicone oil system;

[0032] 2) In another reaction container, add 79.95% ddH2O and heat to 40℃, then add 2.5% hydrolyzed silk protein and 1.5% glycerol triacetate in sequence, stir until completely dissolved, forming a uniform aqueous phase system;

[0033] 3) Slowly pour the pre-emulsified silicone oil prepared in step 1) into the aqueous phase system prepared in step 2), start the high-speed shearing device until a stable emulsion with uniform particle size and no stratification is formed, slowly add 0.75% nano silicon dioxide dispersion liquid, continue to stir to ensure uniform dispersion of the nanoparticles and prevent agglomeration, to obtain an emulsion system;

[0034] 4) The emulsified system prepared in step 3) is cooled to 20-30 °C, 0.3% citric acid-sodium citrate buffer is added, the pH is adjusted to 5.5-6.5, 1% pentylene glycol is added as a preservative, after stirring uniformly, impurities are removed to obtain a softener, and a softener solution with a softener concentration of 5% is prepared.

[0035] Preparation Example 2

[0036] The preparation method of the softener solution is different from that of Preparation Example 1 in that a softener solution with a softener concentration of 10% is prepared, and the remaining steps are the same as those of Preparation Example 1.

[0037] Example

[0038] Example 1

[0039] A preparation method of a softening method for a degumming-free silk base material, comprising the following steps:

[0040] 1) Low-concentration acid dissolution:

[0041] Chitosan powder with a degree of deacetylation of ≥85% and a molecular weight of 10-50 kDa is prepared into a chitosan solution with a concentration of 1% at 35 °C, food-grade citric acid is slowly added, and the pH is adjusted to 5.0 to obtain a chitosan-citric acid solution;

[0042] 2) Preparation of a plasticizing composite system:

[0043] To the chitosan-citric acid solution prepared in step 1), 4% glycerol with a purity of 99% by mass of chitosan powder is added, stirred and heated to 50 °C, stirred at a speed of 250 rpm for 30 min to form a uniform plasticizing composite system;

[0044] 3) Pretreatment and activation of silk base material:

[0045] Take the silk base material and soak it in ddH2O at 40 °C, and treat it with ultrasonic waves at 40 kHz for 20 min. Take out the silk base material and soak it in a previously prepared transglutaminase solution with a concentration of 0.4%, heat to 45 °C, and soak for 20 min, turning the silk base material every 5 min to ensure that the transglutaminase solution is evenly adsorbed on the surface of the silk base material;

[0046] 4) Coating of the plasticizing composite system:

[0047] Soak the silk base material treated in step 3) in the plasticizing composite system prepared in step 2), heat to 30 °C, and soak for 30 min, turning every 5 min to ensure that the plasticizing composite system is evenly adsorbed on the surface of the silk base material;

[0048] 5) Softener solution treatment:

[0049] The silk fabric prepared in step 4) is immersed in the softener solution prepared in Preparation Example 1 at a bath ratio of 1:30 at 45°C for 1 h, and the silk fabric is taken out and washed with water to remove the residual softener solution on the surface of the silk fabric;

[0050] 6) Low-temperature curing and post-treatment:

[0051] The silk fabric prepared in step 5) is pre-dried at 40°C for 10 min, and then final-dried at 50°C to fix the coating and until dry, to ensure that the softening effect is durable.

[0052] Example 2

[0053] A preparation method of a softening method for a degumming-free silk fabric, comprising the following steps:

[0054] 1) Low-concentration acid dissolution:

[0055] Chitosan powder with a deacetylation degree of ≥85% and a molecular weight of 10-50 kDa is prepared into a chitosan solution with a concentration of 1.5% at 35°C, food-grade citric acid is slowly added, and the pH is adjusted to 5.0 to obtain a chitosan-citric acid solution;

[0056] 2) Preparation of a plasticizing composite system:

[0057] To the chitosan-citric acid solution prepared in step 1), 5% of glycerol with a purity of 99% by mass of chitosan powder is added, stirred and heated to 50°C, stirred at a speed of 300 rpm for 30 min to form a uniform plasticizing composite system;

[0058] 3) Pretreatment and activation of silk fabric:

[0059] Take the silk fabric and immerse it in ddH2O at 40°C, and treat it with ultrasonic waves at 40 kHz for 20 min. Take out the silk fabric and immerse it in a previously prepared transglutaminase solution with a concentration of 0.5%, and heat it to 50°C. Soak for 20 min, and turn the silk fabric over every 5 min to ensure that the transglutaminase solution is evenly absorbed on the surface of the silk fabric;

[0060] 4) Coating of the plasticizing composite system:

[0061] The silk fabric treated in step 3) is immersed in the plasticizing composite system prepared in step 2), heated to 30°C, and soaked for 30 min, and turned over every 5 min to ensure that the plasticizing composite system is evenly absorbed on the surface of the silk fabric;

[0062] 5) Softener solution treatment:

[0063] The silk fabric treated in step 4) was immersed in the softener solution prepared in Preparation Example 2, with a bath ratio of 1:30, and immersed at 45°C for 1 h. The silk fabric was taken out and washed with water to remove the residual softener solution on the surface of the silk fabric;

[0064] 6) Low temperature curing and post-treatment:

[0065] The silk fabric treated in step 5) was pre-dried at 40°C for 10 min, and then final-dried at 50°C to fix the coating and until dry, to ensure that the softening effect is durable.

[0066] Performance test

[0067] Test Example 1

[0068] The silk fabric treated by the softening method of the degumming-free silk fabric of Example 1 and Example 2 was respectively detected for softness, and three groups of silk fabric were respectively tested for each group of example. According to GB / T18318.3-2009, the Gley method (swing test) was used, and the LFY-208 swing fabric softness tester was used for testing. A 50g weight was applied to the silk fabric treated by Example 1 and Example 2, and the swing angle of the silk fabric was recorded. The test results are shown in Table 1.

[0069] Table 1: Test results of swing angle of silk fabric

[0070]

[0071] As can be seen from Table 1, the softness improvement rate of Example 1 is between 88-95.8%, and the softness improvement rate of Example 2 is between 88.5-95.8%, indicating that the softening method of the present application can greatly improve the softness of the silk fabric. From the data of different groups, whether it is Example 1 or Example 2, the swing angle of the untreated fabric has certain fluctuations, but the swing angle of the treated fabric is relatively stable, and the softness improvement rate is also relatively close, indicating that the softening method has good stability and repeatability, and can ensure the consistency of product quality in actual production.

[0072] Test Example 2

[0073] The silk fabric treated by the softening method of the degumming-free silk fabric of Example 1 and Example 2 was respectively detected for silk gum retention rate, and three groups of silk fabric were respectively tested for each group of example. The weight of the silk fabric before and after treatment was recorded to calculate the degumming rate. The test results are shown in Table 2.

[0074] Table 2: Degumming rate test of silk fabric

[0075]

[0076] The test results in Table 2 show that the degumming rates for Example 1 ranged from 0.04% to 0.05%, and for Example 2 from 0.02% to 0.05%, with the overall degumming rates being extremely low. This demonstrates that the softening method of the present invention causes virtually no loss of sericin, effectively preserving the sericin in the silk stock. The low fluctuation in degumming rates between batches demonstrates the robustness and repeatability of this softening method, ensuring consistent product quality in actual production.

[0077] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for softening a degumming-free silk blank, characterized in that: The following steps are involved: S1. Take chitosan powder and prepare a chitosan solution with a concentration of 0.5-1.5% at 30-40°C, add food-grade citric acid, adjust the pH to 4.5-5.5, add glycerol, heat and stir to obtain a plasticized composite system; S2. Soak the silk blank in 40°C ddH2O for ultrasonic treatment, take it out and soak it in a 0.3-0.5% transglutaminase solution, heat and stir the silk blank; S3. Immerse the silk blank treated in step S2 into the plasticizing composite system prepared in step S1, take out the silk blank and soak it in a pre-prepared softener solution, take it out and wash it with water and dry it.

2. The method for softening a degumming-free silk blank according to claim 1, wherein: The chitosan powder in step S1 has a deacetylation degree of ≥85% and a molecular weight of 10-50 kDa.

3. The method for softening a degumming-free silk blank according to claim 1, wherein: The amount of glycerol added in step S1 is 3-5% of the mass of the chitosan powder in step S1; The purity of the glycerol is ≥99%.

4. The method for softening a degumming-free silk blank according to claim 1, wherein: In step S1, the temperature is raised to 50° C., the stirring rate is 200-300 rpm, and the stirring time is 30 min.

5. The method for softening a degumming-free silk blank according to claim 1, wherein: The frequency of the ultrasonic treatment in step S2 is 40 kHz, and the ultrasonic treatment time is 20 min.

6. The method for softening a degumming-free silk blank according to claim 5, characterized in that: The temperature of the transglutaminase solution in step S2 is 40-50°C; The silk blank was immersed in the transglutaminase solution for 20 minutes, and the silk blank was turned over every 5 minutes.

7. The method for softening a degumming-free silk blank according to claim 1, wherein: In the process of immersing the silk blank in the plasticizing composite system in step S3, the temperature of the plasticizing composite system is 25-30° C., the immersion time is 30 minutes, and the silk blank is turned over every 5 minutes.

8. The method for softening a degumming-free silk blank according to claim 1, wherein: In the process of soaking the silk blank in the softener solution in step S3, the bath ratio is 1:(30-40), the temperature of the softener solution is 45° C., and the soaking time is 1 hour.

9. The method for softening a degumming-free silk blank according to claim 1, wherein: During the drying process of the silk blank in step S3, the silk blank is pre-dried at 40° C. for 10 minutes and then dried at 50° C.

10. Use of the method for softening degumming-free silk blank according to any one of claims 1 to 9 in raw silk, silk textiles, and blended products.

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