Preparation method of machine washable cashmere sweater

Abstract

The invention belongs to the technical field of treatment of textiles or analogues, and particularly relates to the technical field of washing of fiber products, in particular to a preparation method of a machine washable cashmere sweater. The method comprises the following steps: cleaning cashmere fibers containing skin to obtain cleaned fibers; the bath ratio for cleaning is 1: (20-50); the use amount of a detergent used for cleaning is 1-2.5% (o.w.f); the cleaning comprises ultrasonic cleaning, and the frequency of the ultrasonic cleaning is 17-50 kHz; the power of ultrasonic washing is 0.3-0.5 W / cm < 3 >; the cleaning time is 2 to 15 minutes; performing enzyme treatment on the cleaned fibers by using a compound enzyme solution to obtain enzyme treated fibers; the compound enzyme solution comprises cutinase, and the using amount of the cutinase is 4-10 mL / g; the enzyme treatment time is 5-6 hours; adjusting the pH value of the compound enzyme solution to 8-8.5 by using a buffer solution; the fiber bath ratio after cleaning is 1: (20-50). According to the method, heavy non-protein components of the skin are directionally decomposed through specific low-frequency ultrasonic waves in cooperation with single-component cutinase, the skin removal rate is increased, and then the machine washable capacity of the cashmere sweater is improved through a series of treatment methods.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of processing of textiles or the like, in particular to the technical field of washing of fiber products, and specifically relates to a method for preparing a high-quality cashmere sweater with excellent machine washability by optimizing the cashmere raw material, cleaning the cashmere raw material through ultrasonic and enzyme cooperation, and combining subsequent low-damage carding, dyeing, spinning, knitting and key finishing processes. BACKGROUND

[0002] Cashmere is a kind of precious natural animal fiber, mainly derived from the undercoat of cashmere goats. However, it is necessary to sort, remove coarse hairs, remove impurities, and wash pure cashmere from the mixed hair material, which has complex processing procedures, high technical requirements, and high loss. The main reason is that cashmere fibers are adhered to a large number of skin.

[0003] A Chinese invention patent with publication number CN110499651A discloses a processing method for insect egg shells in cashmere fabric, which removes insect egg shells from cashmere fabric through steps such as ultrasonic and enzyme treatment, so that the number of insect egg shells is reduced.

[0004] A Chinese invention patent with publication number CN107574671A discloses a composite enzyme-based wool fiber impurity remover, which mainly includes a composite enzyme. The application also discloses a method for using the impurity remover. Ultrasonic treatment is used to remove lanolin and plant impurities in raw wool.

[0005] However, the above-mentioned cleaning agents or cleaning methods have a series of problems when directly used for removing impurities from cashmere, such as that cashmere is softer than wool or ordinary cashmere, improper treatment process can easily cause fiber damage and affect its quality; the main impurity in cashmere is skin, which has different properties compared with the impurities in wool or ordinary cashmere, and the treatment effect is not good when directly applying the above-mentioned cleaning agents or cleaning methods. SUMMARY

[0006] The present application aims to provide a preparation method of machine-washable cashmere sweater. The method effectively solves the problem of removing stubborn skin from cashmere raw material, reduces color spots, improves raw material quality, and makes the cashmere sweater product have excellent machine washability through a series of subsequent optimized processing processes.

[0007] The technical solution adopted by the present application to solve the above-mentioned problems is as follows: a preparation method of machine-washable cashmere sweater, including a cashmere cleaning method: cleaning cashmere fibers containing skin to obtain cleaned fibers; the bath ratio of cleaning is 1:(20-50); the amount of detergent used for cleaning is 1-2.5%(o.w.f); the cleaning includes ultrasonic washing, the frequency of ultrasonic washing is 17-50 kHz; the power of ultrasonic washing is 0.3-0.5 W / cm3 ; the washing time is 2-15 min;

[0008] The enzyme treatment fiber is obtained by using a complex enzyme solution to treat the washed fiber; the complex enzyme solution comprises cutinase, and the amount of the cutinase is 4-10 mL / g; the enzyme treatment time is 5-6 h; the pH of the complex enzyme solution is adjusted to 8-8.5 by using a buffer solution; and the bath ratio of the washed fiber is 1: (20-50) ;

[0009] The enzyme treatment fiber is obtained by using a complex enzyme solution to treat the washed fiber; the complex enzyme solution comprises cutinase, and the amount of the cutinase is 4-10 mL / g; the enzyme treatment time is 5-6 h; the pH of the complex enzyme solution is adjusted to 8-8.5 by using a buffer solution; and the bath ratio of the washed fiber is 1: (20-50) ;

[0010] The enzyme treatment fiber is obtained by using a complex enzyme solution to treat the washed fiber; the complex enzyme solution comprises cutinase, and the amount of the cutinase is 4-10 mL / g; the enzyme treatment time is 5-6 h; the pH of the complex enzyme solution is adjusted to 8-8.5 by using a buffer solution; and the bath ratio of the washed fiber is 1: (20-50) ;

[0011] In some embodiments, the detergent is Woolene.

[0012] The enzyme treatment fiber is obtained by using a complex enzyme solution to treat the washed fiber; the complex enzyme solution comprises cutinase, and the amount of the cutinase is 4-10 mL / g; the enzyme treatment time is 5-6 h; the pH of the complex enzyme solution is adjusted to 8-8.5 by using a buffer solution; and the bath ratio of the washed fiber is 1: (20-50) ;

[0013] In some embodiments, the drying comprises centrifugal dehydration and drying.

[0014] In some embodiments, the washing temperature is 40-50℃.

[0015] In some embodiments, the enzyme treatment temperature is 50-60℃.

[0016] In some embodiments, the buffer solution is a Tris-HCl buffer solution.

[0017] In some embodiments, the amino acid composition of the cashmere fiber and the skin includes aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine and arginine.

[0018] In some embodiments, the amino acid content of the cashmere fiber is 90-96 g / 100 g.

[0019] In some embodiments, the amino acid content of the skin is 70-73 g / 100 g.

[0020] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description.

[0021] In summary, the present application has the following advantages:

[0022] 1. This invention uses specific low-frequency ultrasound (17–50kHz) in conjunction with a single-component keratinase to directionally decompose the non-protein components of the skin, thereby improving the skin removal rate and solving the problem of difficult removal of dead skin in existing technologies. Combined with subsequent low-damage combing, dyeing, spinning, knitting and key finishing processes, a high-quality cashmere sweater with excellent machine washability is finally produced.

[0023] 2. The low-frequency ultrasound of this invention avoids the outward curling of fiber scales caused by high-frequency ultrasound, preventing damage to the cashmere protein structure and ensuring fiber quality.

[0024] 3. This invention further optimizes parameters such as enzyme concentration and enzyme treatment time, thereby further improving the fiber quality obtained by the cleaning process. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings: The above and other features, advantages, and aspects of the various embodiments of the present invention will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements.

[0026] Figure 1 This is a schematic diagram of the colored dots on the felt body in this invention.

[0027] Figure 2 This is a schematic diagram of the colored dots on the yarn in this invention.

[0028] Figure 3 This is a schematic diagram of the skin being bonded to cashmere fibers in this invention.

[0029] Figure 4 This is a schematic diagram of the results of Embodiment 2 of the present invention.

[0030] Figure 5 This is a schematic diagram of cashmere fibers in Example 3 of the present invention.

[0031] Figure 6 This is a schematic diagram of cashmere fibers in Example 1 of the present invention.

[0032] Figure 7 This is a schematic diagram of cashmere fibers in Example 4 of the present invention.

[0033] Figure 8 This is a schematic diagram of cashmere fibers in Example 5 of the present invention.

[0034] Figure 9 This is a schematic diagram of cashmere fibers in Comparative Example 1 of this invention.

[0035] Figure 10 This is a schematic diagram of the dandruff removal rate results in Examples 1 and 7-14 of the present invention.

[0036] Figure 11 This is a schematic diagram of the dandruff removal rate results in Examples 1 and 15-22 of the present invention.

[0037] Figure 12 This is a schematic diagram illustrating the cleaning effect of Examples 1 and 23-25 ​​of the present invention.

[0038] Figure 13 This is a schematic diagram of the cleaning effect in Examples 1 and 26-29 of the present invention.

[0039] Figure 14 This is a schematic diagram of the cleaning effect in Examples 1 and 30-32 of the present invention.

[0040] The features marked in the attached diagram are as follows: 1. Down body, 2. Color spot, 3. Down yarn, 4. Skin, 5. Cashmere fiber. Detailed Implementation

[0041] The following description, in conjunction with the accompanying drawings, illustrates exemplary embodiments of the present invention, including various details to aid understanding. These details should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0042] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below. For simplicity, "cashmere" as used in the embodiments of this disclosure generally refers to cashmere from goats, unless explicitly stated that cashmere is not cashmere from goats.

[0043] As a further supplement to the background technology, the cashmere fiber is collected by combing, which involves using a special iron comb to comb the cashmere off the goat. However, during the combing process, some skin and impurities from the goat are also combed off, resulting in the presence of some impurities in the raw cashmere, including skin, sweat, coarse hair, and two types of hair, with skin being the main component.

[0044] Furthermore, during dyeing, due to the differences in composition and structure between cashmere fibers and cashmere dander, the same dyes and processing conditions will result in darker color spots on cashmere dander, especially when dyeing lighter-colored cashmere varieties, where the phenomenon is more pronounced. Figure 1 , 2As shown, color spot 2 is located between cashmere body 1 and the yarn 3 formed after the cashmere body 1 is spun. The presence of skin flakes affects the uniformity of cashmere fiber dyeing, thus affecting the appearance quality of cashmere products. Historically, most cashmere processing and garment companies have relied on manual removal of these skin flakes. This method is not only difficult to completely remove all color spots, but also wastes time and incurs high labor costs.

[0045] Cashmere fibers and goat skin flakes are both protein materials, and the differences in their composition and structure are undoubtedly the essential reason for the resulting staining spots on the skin flakes. Therefore, this disclosure first analyzes the composition and structure of the cashmere fibers containing skin flakes, as shown in Table 1.

[0046] Amino acid species Cashmere fibre Cashmere fibre skin Aspartic acid 5.864 5.250 Threonine 5.037 3.398 Serine 7.065 5.952 Glutamic acid 13.642 10.390 Proline 7.749 4.030 Glycine 4.135 4.415 Alanine 3.447 3.382 Cysteine 9.213 1.689 Valine 4.311 3.683 Methionine 1.125 1.220 Isoleucine 3.978 3.284 Leucine 6.825 5.753 Tyrosine 4.928 3.553 Phenylalanine 3.510 2.962 Lysine 3.813 4.509 Histidine 1.413 1.808 Arginine 8.484 6.414 Total 94.540 71.692

[0047] Table 1. Amino acid composition of cashmere fibers and their skin (g / 100g)

[0048] As shown in Table 1, the total content of 17 amino acids in the cashmere sample and the skin is different, with the skin containing a lower total amino acid content than the cashmere sample. The cashmere amino acid content is 94.540 g / 100g, while the hydrolyzed skin contains only 71.692 g / 100g of the 17 amino acids, indicating a lower amino acid content in the skin compared to the cashmere sample. The content of each amino acid varies significantly between the samples, and the content of the same amino acid also differs between cashmere fibers and their skin. Overall, except for glycine, lysine, and histidine, the content of other amino acids is higher in cashmere fibers than in their skin. Simultaneously, the skin contains significantly less cysteine ​​and proline than cashmere fibers. The low total amino acid content indicates the presence of non-protein components in the skin, such as lipids or keratinized substances. These components can easily cause color spot problems during washing or dyeing. Therefore, reagents for removing skin should target these differences, prioritizing compositions that specifically decompose non-protein components or low-content amino acids, while avoiding damage to the protein structure of cashmere fibers.

[0049] Based on the characteristics of the amino acid composition of skin, existing technologies typically use bio-enzymes as compositions to decompose non-protein components or low-content amino acids. Bio-enzymes possess high specificity and mild reaction conditions, selectively decomposing non-protein components of the skin while protecting the intact protein structure of cashmere fibers. Since keratin is a non-protein polymer abundant in the skin, keratinase is typically used to specifically hydrolyze the ester bonds of keratin to achieve a removal effect.

[0050] Furthermore, the skin flakes include both live and dead skin flakes. Live skin flakes float on the fiber surface and are easily detached during pretreatment. However, dead skin flakes are different; they adhere to the fibers and cannot be removed even after pretreatment processes such as rinsing and combing. The adhesion structure between cashmere fibers and their skin flakes was observed using a 145x digital optical microscope. Figure 3 As shown, it is clearly observed that the skin 4 adheres to the cashmere fiber 5, with the cashmere fiber 5 directly penetrating the skin 4, forming a "penetrating skin". This skin is firmly attached to the cashmere fiber and tightly bound to it, affecting the contact process between the skin and the enzyme. Therefore, before enzyme treatment, the skin is usually pretreated with ultrasound to increase the contact area between the skin and the enzyme, thereby increasing the enzyme reaction rate.

[0051] Both CN110499651A and CN107574671A utilize keratinase in their compound enzyme components to treat non-cashmere fibers, and employ ultrasonic cleaning before or during enzyme treatment. However, these existing technologies have drawbacks: First, keratinase constitutes only a portion of the compound enzyme, resulting in poor specific removal of skin residue; second, insufficient control over ultrasonic conditions leads to easy damage to cashmere fibers. Furthermore, unremoved skin residue can affect the washability of the resulting cashmere sweaters, especially their machine washability.

[0052] The following will combine Figures 1 to 14 This invention provides a detailed description of a method for preparing a machine-washable cashmere sweater.

[0053] A method for preparing a machine-washable cashmere sweater, wherein the cashmere washing method includes:

[0054] The cashmere fibers containing the outer skin are cleaned to obtain cleaned fibers; the liquor ratio for cleaning is 1:(20-50); the amount of detergent used for cleaning is 1-2.5% (owf); the cleaning includes ultrasonic cleaning at a frequency of 17-50kHz; the power of ultrasonic cleaning is 0.3-0.5W / cm². 3 The cleaning time is 2-15 minutes.

[0055] The washed fibers were treated with a compound enzyme solution to obtain enzyme-treated fibers. The compound enzyme solution included keratinase, and the amount of keratinase was 4-10 mL / g. The enzyme treatment time was 5-6 h. The pH of the compound enzyme solution was adjusted to 8-8.5 using a buffer solution. The fiber bath ratio after washing was 1:(20-50).

[0056] Furthermore, the detergent is optimized to obtain better washing effects. Based on this, the detergent is Maonengjing. In the embodiments of the present disclosure, the composition of Maonengjing is Maonengjing A defined in Q / 12DYQ 007-2019 "Maonengjing".

[0057] Furthermore, the enzyme-treated fiber needs to be further processed for ease of use. Based on this, the cleaning method further includes post-treating the enzyme-treated fiber to obtain the treated fiber; the post-treatment includes washing and drying. Washing includes inactivating the enzyme and removing impurities. The purpose of inactivating the enzyme is to terminate the enzymatic reaction and prevent the residual enzyme from continuously acting to damage the fiber. The operation process includes heating the enzyme-treated fiber-skin mixture to 85-90 °C and maintaining it at a constant temperature for 5-10 min, so that the cutinase is completely inactivated by high temperature. Impurity removal is filtration and washing. Using a vacuum filtration device, the liquid-solid separation of the enzyme-inactivated mixed solution is carried out. The fiber is rinsed 3-5 times with warm water at 40-50 °C to remove the residual enzyme and hydrolysis products on the surface; 0.4-0.5% glacial acetic acid solution (room temperature) is added and soaked for 5-7 min to neutralize the alkaline buffer (Tris-HCl pH≈8); it is rinsed with deionized water at room temperature until pH≈7. Drying includes centrifugal dehydration (1000-1500 rpm, 3-5 min) to reduce the water content of the fiber to 45-50%. Drying also includes drying in a circulating air oven at a temperature of 40-45 °C for 18-24 h. For other operation methods involving cleaning or drying, those skilled in the art can select the forms that can be achieved according to the parameters in the specification by themselves, and the embodiments of the present disclosure do not further limit the specific forms of cleaning or drying.

[0058] Furthermore, the treated fibers are combed, dyed, spun, knitted, and finished to obtain the machine-washable cashmere sweater. The combing process is a low-damage combing method, controlling the speed, spacing, and airflow parameters of the main combing components such as the cylinder, working rollers, and doffer of the combing machine to optimize combing intensity, minimize fiber damage and short fiber content, and obtain combed slivers while maintaining fiber length and strength. The combed slivers or yarns are then dyed, with the addition of leveling agents and fiber protectants. Thanks to the effective removal of the outer layer, dyeing uniformity is significantly improved, and color spot issues are greatly reduced. The dyed slivers or washed cashmere are then spun, using compact spinning or Siro spinning processes to increase yarn density and strength. The twist design is optimized to balance yarn strength and softness, resulting in cashmere yarn. The cashmere yarn is then knitted into cashmere sweater pieces on a circular knitting or flat knitting machine. The finishing process mainly involves applying a shrink-proofing treatment to the knitted cashmere sweater pieces. This treatment uses polyamide-epoxychloropropane resin or water-based polyurethane resin at a temperature of 30-50℃ for 20-40 minutes. Excess finishing agent is thoroughly rinsed off with clean water, followed by centrifugal dehydration. The sweater is then dried and heat-set at 70-90℃ for 10-30 minutes on setting equipment such as a rotary dryer, steam ironing platform, or setting rack to stabilize resin cross-linking, fix fiber morphology, and achieve a durable shrink-proof effect and a machine-washable cashmere sweater with good dimensions.

[0059] Furthermore, the washing temperature is 40-50℃, and the enzyme treatment temperature is 50-60℃, in order to achieve the best treatment effect on cashmere fibers.

[0060] Furthermore, based on the above description, the cashmere fibers targeted by this cleaning method have an amino acid composition including aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, cysteine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine. The amino acid content of the cashmere fiber is 90-96 g / 100 g, and the amino acid content of the skin is 70-73 g / 100 g. Optimal treatment results can be obtained for this type of cashmere.

[0061] The following are some specific embodiments (including examples and comparative examples) to help illustrate the cashmere washing method in the preparation method of machine-washable cashmere sweaters of the present invention. It should be understood that the following embodiments are only examples and are not intended to limit the present invention.

[0062] Example 1:

[0063] Cashmere cleaning methods include:

[0064] The cashmere fibers are washed to obtain the washed fibers;

[0065] The bath ratio for cleaning is 1:50;

[0066] The detergent used for cleaning included 2.5% (owf) wool cleaner, with the remainder being water;

[0067] The cleaning process includes ultrasonic cleaning; in this embodiment, the ultrasonic cleaning frequency is 25 kHz.

[0068] The power of ultrasonic cleaning is 0.5W / cm. 3 .

[0069] The cleaning temperature is 50℃ and the cleaning time is 10 minutes.

[0070] The washed fibers were treated with a compound enzyme solution to obtain enzyme-treated fibers.

[0071] The complex enzyme solution includes keratinase, with a keratinase dosage of 8 mL / g;

[0072] The enzyme treatment temperature is 60℃;

[0073] The enzyme treatment time is 5 hours;

[0074] The pH of the complex enzyme solution was adjusted to 8 using a buffer solution.

[0075] The buffer solution is Tris-HCl buffer solution.

[0076] The fiber bath ratio after washing is 1:50;

[0077] The enzyme-treated fibers were then post-treated to obtain the treated fibers.

[0078] Post-processing includes washing and drying;

[0079] Drying refers to baking.

[0080] Example 2:

[0081] In this embodiment, the difference from Embodiment 1 is that the frequency of ultrasonic washing is 17kHz.

[0082] Example 3:

[0083] In this embodiment, the difference from Embodiment 1 is that the frequency of the ultrasonic cleaning is 20kHz.

[0084] Example 4:

[0085] In this embodiment, the difference from Embodiment 1 is that the frequency of the ultrasonic cleaning is 28 kHz.

[0086] Example 5:

[0087] In this embodiment, the difference from Embodiment 1 is that the frequency of the ultrasonic cleaning is 50 kHz.

[0088] Example 6:

[0089] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 2 mL / g.

[0090] Example 7:

[0091] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 4 mL / g.

[0092] Example 8:

[0093] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 6 mL / g.

[0094] Example 9:

[0095] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 10 mL / g.

[0096] Example 10:

[0097] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 20 mL / g.

[0098] Example 11:

[0099] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 30 mL / g.

[0100] Example 12:

[0101] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 40 mL / g.

[0102] Example 13:

[0103] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 50 mL / g.

[0104] Example 14:

[0105] In this embodiment, the difference from Example 1 is that the amount of keratinase used is 60 mL / g.

[0106] Example 15:

[0107] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 1 hour.

[0108] Example 16:

[0109] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 2 hours.

[0110] Example 17:

[0111] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 3 hours.

[0112] Example 18:

[0113] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 4 hours.

[0114] Example 19:

[0115] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 6 hours.

[0116] Example 20:

[0117] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 7 hours.

[0118] Example 21:

[0119] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 8 hours.

[0120] Example 22:

[0121] In this embodiment, the difference from Example 1 is that the enzyme treatment time is 9 hours.

[0122] Example 23:

[0123] In this embodiment, the difference from Embodiment 1 is that the cleaning time is 2 minutes.

[0124] Example 24:

[0125] In this embodiment, the difference from Embodiment 1 is that the cleaning time is 5 minutes.

[0126] Example 25:

[0127] In this embodiment, the difference from Embodiment 1 is that the cleaning time is 15 minutes.

[0128] Example 26:

[0129] In this embodiment, the difference from Embodiment 1 is that the bath ratio for cleaning is 1:40.

[0130] Example 27:

[0131] In this embodiment, the difference from Embodiment 1 is that the bath ratio for cleaning is 1:30.

[0132] Example 28:

[0133] In this embodiment, the difference from Embodiment 1 is that the bath ratio for cleaning is 1:20.

[0134] Example 29:

[0135] In this embodiment, the difference from Embodiment 1 is that the bath ratio for cleaning is 1:20.

[0136] Example 30:

[0137] In this embodiment, the difference from Embodiment 1 is that the detergent dosage is 2% (owf).

[0138] Example 31:

[0139] In this embodiment, the difference from that in Embodiment 1 is that the detergent dosage is 1.5% (owf).

[0140] Example 32:

[0141] In this embodiment, the difference from Embodiment 1 is that the detergent dosage is 1% (owf).

[0142] Comparative Example 1:

[0143] Referring to Chinese invention patent publication number CN106120292A, which discloses a method for skinning cashmere, the minimum frequency of ultrasonic treatment used is 500kHz. Based on this, the difference between this comparative example and Example 1 is that the frequency of ultrasonic washing is 500kHz.

[0144] Comparative Example 2:

[0145] Referring to Chinese invention patent publication number CN110499651A, which discloses a method for treating insect eggshells in cashmere fabrics, the enzyme treatment solution used includes keratinase, protease, and glycoside hydrolase. Based on this, in this comparative example, the difference from Example 1 is that the composite enzyme solution consists of keratinase, protease, and glycoside hydrolase, wherein the concentration of keratinase in the enzyme treatment solution is 8 mg / g; the concentration of protease is 1 mg / g; and the concentration of glycoside hydrolase is 1.5 mg / g.

[0146] Furthermore, the treated fibers obtained in Examples 1 to 22 and Comparative Examples 1 and 2 were tested to further verify their technical effects.

[0147] Experimental Example 1: The Influence of Ultrasonic Frequency.

[0148] In this experimental example, the appearance of cashmere fibers under different ultrasonic frequencies was observed using a microscope to determine the degree of damage to the cashmere fibers. (Reference) Figures 4-9Microscopic images of the appearance of fibers after ultrasonic water cleaning at 17, 20, 25, 28, 50, and 500 kHz are shown, respectively, from Examples 1 to 5 and Comparative Example 1. Figures 4-9 It can be seen that the appearance of cashmere fibers is normal after low-frequency cleaning, while slight outward curling of fiber scales occurs at 50kHz, and severe outward curling of fiber scales occurs at 500kHz. Considering the cleaning effect, the ideal cleaning frequency is 25kHz.

[0149] Based on this experimental example, and according to the technical inspiration of CN106120292A, the minimum ultrasonic cleaning frequency for cashmere fibers given is 500kHz, which is much greater than the ideal cleaning frequency (25kHz) in the experimental results. This indicates that the embodiments of this disclosure propose a more advanced ultrasonic frequency (25kHz) and its range (17-50kHz) for cleaning cashmere fibers.

[0150] Experimental Example 2: Dandruff Removal Rate Test.

[0151] Weigh out cashmere fiber with a weight of m1, and after processing, obtain treated fiber with a weight of m2.

[0152] Calculate the dandruff removal rate according to formula (1).

[0153] dandruff removal rate = (m1 - m2) / m1 × 100% (1)

[0154] The study investigated the damage to cashmere treated with keratinase under suitable conditions by measuring the dandruff removal rate.

[0155] After washing, the cashmere was treated at a constant temperature of 60°C in a keratinase reaction solution, with the pH maintained at 8 using Tris-HCl buffer solution at a bath ratio of 1:50. After 6 hours, the temperature was raised to 90°C for enzyme inactivation treatment for 5 minutes. After filtration, it was dried at 45°C for 24 hours until the mass was constant, and then weighed as m2. Different dandruff removal rates were obtained by adjusting different concentrations of keratinase. Figure 10 The figure shows the dandruff removal rates of Examples 1, 6 to 14. The curves in the figure show that as the concentration of keratinase increases, the removal rate of dandruff from cashmere skin first increases and then decreases, reaching a maximum of 29% at a keratinase concentration of 8 mL / g (the highest value in the figure). A plausible explanation is that too low an enzyme concentration is insufficient to fully hydrolyze specific sites on the substrate, resulting in a slow hydrolysis process, while too high an enzyme concentration may induce competition for certain enzymatic reactions, thus inhibiting the degree of hydrolysis. This suggests that 8 mL / g of keratinase is the optimal concentration.

[0156] Experimental Example 3: Test on the effect of reaction time on dandruff removal rate.

[0157] At the optimal temperature of 60℃, pH 8, and keratinase concentration of 8 mL / g, cashmere dander was treated for different reaction times to investigate the effect of reaction time on dander removal rate. The results are as follows: Figure 11 The figures show the dandruff removal rates for Examples 1, 15 to 22, i.e., reaction times of 1-8 hours. The curves in the figures show that within the 1-5 hour range, the removal rate of cashmere dandruff gradually increases with increasing time. However, after 5 hours, the removal rate decreases, indicating that the keratin substrate is essentially hydrolyzed, and further time would damage the structure of the cashmere itself. Therefore, for a certain amount of cashmere dandruff, using keratinase for 5 hours is most suitable. The process conditions for removing cashmere dandruff using keratinase are: keratinase dosage 8 mL / g, pH 8, reaction temperature 60℃, reaction time 5 hours, and bath ratio 1:50. At this time, the dandruff removal rate reaches 29%.

[0158] Experimental Example 4: The Influence of Ultrasonic Cleaning on the Cleaning Process.

[0159] By adjusting the cleaning time, liquor ratio, and detergent dosage, and conducting cleaning under both ultrasonic and conventional conditions, the effects of cleaning time, liquor ratio, and detergent dosage on the cleaning effect can be obtained. See Figure 12 Examples 1, 23 to 25 demonstrate the effect of cleaning time on cleaning results; see Figure 13 Examples 1, 26 to 29 demonstrate the effect of liquor ratio on cleaning effect; see Figure 14 Examples 1, 30, and 32 demonstrate the effect of detergent on the results. Whiteness is represented by the ratio of pure white area to the total area per unit area of ​​cashmere fiber. Cleaning was performed under normal conditions, i.e., under the same conditions, but with ultrasonic washing replaced by the cleaning method described in Section 5.1.1 of the Chinese National Standard GB / T 8629-2001 "Home Washing and Drying Procedures for Textile Testing".

[0160] It is evident that, within a certain range, the washing time and amount of detergent significantly affect the final cleaning effect, while the amount of water used also has some impact. However, under ultrasonic action, a cleaning time of approximately 2 minutes can achieve the same effect as a 15-minute cleaning under conventional conditions. Furthermore, ultrasonic cleaning can achieve good cleaning results with less additives and water.

[0161] Experimental Example 5: Staining Test.

[0162] In this experimental example, 0.5% (omf) Lanasol Blue 8G was used as the dye to dye cashmere. The dyeing method was based on the publicly available information in Section 3.3.1 (I) of the Traditional Dyeing Process in "Study on the Color Homogeneity of Cashmere Fibers" (Su Xiaohua, Xi'an University of Technology, 2019).

[0163] Cashmere fibers of the same weight were selected. In this experimental example, 100g of cashmere fibers were selected, and the above tests were conducted according to the methods described in Example 1, Comparative Example 1, and Comparative Example 2. The dyed cashmere was laid flat on a plane to ensure that all color spots were visible, and the number of color spots was recorded. Color spots with a diameter greater than 3mm and whose color was clearly distinguishable from the surrounding color were considered valid color spots and recorded. The test was conducted three times, and the average value was taken. The results are shown in Table 2.

[0164] Number of colour points (one measurement) Number of colour points (two measurements) Number of colour points (three measurements) Average (rounded up) Example 1 3 4 3 4 Comparative Example 1 9 8 8 9 Comparative Example 2 14 12 13 13

[0165] Table 2. Staining test results of Example 1, Comparative Example 1, and Comparative Example 2

[0166] The number of pigment spots directly reflects the relative amount of residual skin after cashmere fiber treatment. Referring to the results in Table 2, it can be seen that adjusting the ultrasonic frequency to 25kHz, combined with keratinase, significantly decomposes the skin, resulting in a substantial reduction in the number of pigment spots. However, when the ultrasonic frequency returns to 500kHz, the number of pigment spots increases, indicating that excessively high ultrasonic frequencies affect the keratinase's ability to decompose the skin. Simultaneously, with the relative concentration of keratinase remaining constant, the number of pigment spots increases significantly when used in conjunction with proteases and glycoside hydrolases, indicating that excess non-keratinases affect the binding process between keratinase and skin, leading to poor skin decomposition.

[0167] Furthermore, the specific method for preparing machine-washable cashmere sweaters based on the above-mentioned cashmere fibers involves combing, dyeing, fulling, spinning, knitting, and finishing the treated fibers. The dyeing process specifically involves controlling the temperature at 90-98℃ and the dyeing time at 65-80 minutes to obtain loose fibers. The loose fibers are then subjected to machine-washable finishing, drained when the pH is 6, and dried in a dryer at 45-50℃ and a rotation speed of 12-15 seconds per revolution to obtain semi-finished cashmere.

[0168] The dyeing process involves controlling the temperature at 90-98℃ and the time at 65-80 minutes to ensure the dye fully penetrates the fiber while avoiding excessive heat that could damage it. The appropriate temperature is selected based on the dye color; for example, 90℃ is used for light-colored dyes, and 98℃ for dark-colored dyes. Furthermore, draining the water at pH 6 helps stabilize the dye molecules, preventing dye loss during machine washing. Thanks to the skin removal process during pretreatment, this further reduces color spot issues and ensures that the cashmere sweater retains its vibrant color and resists fading even after multiple machine washes.

[0169] Furthermore, maintaining a pH level near neutral and using a low-temperature drying method helps reduce chemical degradation of the fibers, improving colorfastness. The aforementioned cashmere fibers have undergone skin removal to improve dyeing uniformity; this optimization further enhances the stability of the dyeing process, making cashmere sweaters more resistant to the chemical and mechanical effects of machine washing.

[0170] The specific steps of the fulling process are as follows: the semi-finished cashmere is machine washed and treated, neutralized to pH 6-7, and then added to an aqueous solution of 1.5% by weight of a cashmere absorbent. The solution is heated to 35°C and soaked for 60 minutes. Then, it is taken out, rinsed with clean water, and dried to control the moisture regain within the range of 14-16%. "% by weight" indicates the weight ratio of the corresponding substance to the cashmere fiber.

[0171] The fulling process effectively cleans the fibers and promotes their directional alignment. Subsequently, the drying temperature is controlled at around 45℃ and the moisture regain at 14-16%, maintaining internal moisture balance and reducing internal stress. Maintaining a moisture regain of 14-16% ensures the cashmere fibers retain appropriate moisture content after drying, preventing brittleness from over-drying or mildew from over-wetting. This significantly improves the dimensional stability of the cashmere sweater, making it less prone to shrinkage or deformation during machine washing, especially during water washing and spin drying. Both the dyeing and fulling processes utilize low-temperature treatments to avoid damaging the cashmere protein structure with high temperatures. Slow drying reduces mechanical stress, preventing fiber tangling or pilling.

[0172] Furthermore, the machine-washable finishing process specifically involves adding 0.2-0.5% by weight of machine-washable resin and 0.1-0.2% by weight of organic amine catalyst, and treating at 80-100℃ for 15-20 minutes. This allows the resin to adsorb and initially form a cross-linked film with the cashmere fibers, achieving color fixation, improving fiber strength, and reducing shrinkage. Regarding the temperature setting, this range represents a relatively safe "high temperature" range that cashmere fibers can withstand. It provides sufficient energy for the resin to quickly complete cross-linking and curing under the action of the catalyst. Excessive temperature will exacerbate damage to the cashmere fibers, leading to protein denaturation, decreased strength, rougher hand feel, and yellowing.

[0173] Furthermore, the machine-washable resin is a polyamide epichlorohydrin resin. Polyamide epichlorohydrin resin is a reactive resin. Its molecular chain contains multiple highly reactive epoxy groups. Under the catalysis of an organic amine catalyst and under alkaline to neutral conditions at 80-100℃, these epoxy groups can covalently bond with functional groups such as amino (-NH2), carboxyl (-COOH), and hydroxyl (-OH) groups on cashmere fiber protein molecules. This strong fiber-resin-fiber three-dimensional cross-linked network fundamentally restricts the relative movement of cashmere fibers under wet, hot, and mechanical forces such as washing agitation. It effectively "locks in" the fiber's scale structure, greatly inhibiting wool / cashmere felting.

[0174] Furthermore, the polyamide epichlorohydrin resin is Hercosett 57 (CAS: 25212-19-5). Hercosett 57 is formulated for precious protein fibers such as wool and cashmere, and the cross-linked film it forms is very thin and elastic.

[0175] Furthermore, the organic amine catalyst is triethanolamine (TEA). As a tertiary amine, TEA's aqueous solution is alkaline, providing the necessary alkaline environment for the crosslinking reaction of polyamide epichlorohydrin resin (Hercosett 57), a prerequisite for the ring-opening of epoxy groups and their reaction with the fiber. TEA molecules also act as buffer crosslinking agents; when one end of a TEA molecule reacts with the resin on one fiber, and the other end reacts with the resin on another fiber, it acts as a flexible, longer "bridge" between the fibers. Compared to the rigid, short crosslinks formed directly by the resin, this crosslinking network formed with the participation of TEA is more flexible. This directly translates into a softer, more elastic feel in cashmere sweaters, effectively avoiding the fiber stiffness that can result from resin crosslinking.

[0176] Furthermore, the re-washable finishing process specifically involves adding 1-3% by weight of an acidic machine-washable compound resin, 0.5-1% by weight of a metal salt catalyst, and a pH of 4-5, and soaking at 40-45°C for 20-30 minutes. The machine-washable compound resin includes one or two of polyamide epichlorohydrin resin or maleic anhydride compound. For example, the polyamide epichlorohydrin resin may use Hercosett 57 and maleic anhydride compound in a ratio of 80-90% Hercosett 57 and 20-10% maleic anhydride. The introduction of Hercosett 57 and maleic anhydride compound allows their anhydride or carboxyl groups to bond with the fiber primarily through ionic and hydrogen bonds under acidic conditions, forming a soft, elastic film on the fiber surface. This film further smooths the fiber scales, reduces friction, and increases the smoothness and elasticity of the fiber, resulting in better shape recovery during machine washing of the cashmere sweater. Furthermore, cashmere is a protein fiber, and its isoelectric point is generally between pH 4.5 and 5.0. Under this pH environment, the fiber exhibits minimal swelling and the most stable chemical properties.

[0177] Furthermore, the metal salt catalyst includes ferric chloride or zinc chloride. Both ferric chloride and zinc chloride are strong Lewis acids; the addition of a small amount of ferric chloride can significantly enhance the activity of the entire catalytic system, potentially allowing for a reduction in overall processing temperature or a shortening of processing time. Additionally, the proportion of ferric chloride can be controlled at a low level, pre-complexed with zinc chloride to suppress the release and oxidizing properties of Fe³⁺, further ensuring the overall mildness of the treatment bath. In a preferred embodiment, the metal salt catalyst is a mixture of zinc chloride and ferric chloride, wherein the mass ratio of zinc chloride to ferric chloride is (3:1) to (10:1), preferably (5:1). The total amount of metal salt catalyst used is 0.5% of the fiber mass. The processing temperature is slightly reduced from 40-45°C to 38-42°C to further reduce thermal damage to the cashmere fibers.

[0178] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

[0179] The above are merely optional embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a machine-washable cashmere sweater, characterized in that, The method includes a cashmere cleaning process: cleaning cashmere fibers containing skin to obtain cleaned fibers; the liquor ratio for cleaning is 1:(20-50); the amount of detergent used for cleaning is 1-2.5% (owf); the cleaning includes ultrasonic cleaning at a frequency of 17-50 kHz; the power of the ultrasonic cleaning is 0.3-0.5 W / cm². 3 The cleaning time is 2-15 minutes. The washed fibers are treated with a compound enzyme solution to obtain enzyme-treated fibers; the compound enzyme solution includes keratinase, and the amount of keratinase is 4-10 mL / g; the enzyme treatment time is 5-6 h; the pH of the compound enzyme solution is adjusted to 8-8.5 using a buffer solution; the bath ratio of the washed fibers is 1:(20-50). It also includes post-treatment of the enzyme-treated fiber to obtain treated fiber; It also includes combing, dyeing, fulling, spinning, knitting and finishing of the treated fibers to obtain the machine-washable cashmere sweater.

2. The preparation method according to claim 1, characterized in that, The detergent is hair remover; the post-treatment includes washing and drying; the drying includes centrifugation and dehydration and baking; the washing temperature is 40-50℃; the enzyme treatment temperature is 50-60℃; the buffer solution is Tris-HCl buffer solution.

3. The preparation method according to claim 1, characterized in that, The amino acid composition of the cashmere fiber and skin includes aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, and arginine; the amino acid content of the cashmere fiber is 90-96g / 100g.

4. The preparation method according to claim 1, characterized in that, The specific steps of the dyeing process are as follows: The temperature was controlled at 90-98℃, and the dyeing time was 65-80 minutes to obtain loose fibers; The loose fibers are machine washable, drained when the pH is 6, and then dried in a dryer at 45-50°C and 12-15 seconds per revolution to obtain semi-finished cashmere.

5. The preparation method according to claim 4, characterized in that, The specific steps of the fulling process are as follows: The semi-finished cashmere is machine washed and treated, neutralized to pH 6-7, and then added to a 1.5% aqueous solution of wool cleaner. The solution is heated to 35°C and soaked for 60 minutes. The cashmere is then removed, rinsed with clean water, and dried to control the moisture regain within the range of 14-16%.

6. The preparation method according to claim 4, characterized in that, The machine-washable finishing process involves adding 0.2-0.5% by weight of machine-washable resin and 0.1-0.2% by weight of organic amine catalyst, and treating at 80-100℃ for 15-20 minutes.

7. The preparation method according to claim 6, characterized in that, The machine-washable resin is a polyamide epichlorohydrin resin; the polyamide epichlorohydrin resin is Hercosett 57; and the organic amine catalyst is triethanolamine.

8. The preparation method according to claim 5, characterized in that, The rewashable finishing process specifically involves adding 1-3% by weight of acidic rewashable compound resin, 0.5-1% by weight of metal salt catalyst, pH 4-5, and soaking at 40-45℃ for 20-30 minutes.

9. The preparation method according to claim 8, characterized in that, The machine-washable compounded resin includes one or two of polyamide epichlorohydrin resin or maleic anhydride compound.

10. The preparation method according to claim 8, characterized in that, The metal salt catalyst comprises one or a combination of two of ferric chloride or zinc chloride.

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