Denim-like fabric and preparation process thereof

Abstract

The invention relates to the field of textile fabrics, and particularly discloses a jean-like fabric and a preparation process thereof. The preparation process of the imitation jean fabric comprises the following steps: weaving: weaving by taking polylactic acid fibers subjected to oxygen plasma pretreatment as warp yarns and cotton fibers as weft yarns to obtain gray fabric; dyeing: carrying out padding dyeing on the gray fabric by using indigo dye liquid with the pH value of 6-7; desizing: sequentially carrying out water washing, oxidation treatment, soaping, water washing and drying on the gray fabric; and after-finishing: carrying out after-finishing on the desized gray fabric by adopting fading treatment, sizing and preshrinking processes in sequence to obtain the imitation jean fabric. The imitation jean fabric has the advantages of natural color transition, wear resistance, wrinkle resistance, stretch resistance and tear resistance.

Description

Technical Field

[0001] The present application relates to the technical field of textile fabrics, and more specifically, to a denim-like fabric and a preparation process thereof. Background Art

[0002] Denim was originally a fabric used by shepherds in the American West. It has blue and white lines, with the warp yarns mostly indigo and the weft yarns bleached or light gray. Now this fabric has been accepted by people of all social classes and ages.

[0003] Currently, the warp yarns of denim are dyed with indigo, a dark blue dye that can be either naturally derived or synthetic. During the dyeing process, the warp yarns are soaked in a liquid containing indigo dye, which penetrates the fibers of the yarn and gives the warp a blue color. The weft yarns are generally left in their natural color or bleached, usually white. When weaving denim, the blue warp yarns are interwoven with the white weft yarns, creating the classic blue and white look of denim. This unique color combination gives denim a unique texture effect.

[0004] In the prior art, a Chinese invention patent application document with application number CN2023118282730 discloses a method for preparing imitation denim fabrics, including pretreatment: desizing, refining and bleaching Dahua pure polyester yarn; cationic modification: drying the pretreated warp yarn and then subjecting it to ultrasonic-assisted cationic modification to obtain modified polyester; paint dyeing: subjecting the modified polyester to ultrasonic-assisted blue paint dyeing; color fixation: drying the paint-dyed warp yarn and then using an adhesive to fix the color, and then pre-baking and baking to obtain dyed polyester, weaving: weaving with dyed polyester as warp yarn and OE pure polyester yarn as weft yarn to obtain grey cloth; post-finishing: desizing and washing the grey cloth to obtain an imitation denim fabric with a washed style.

[0005] In the preparation method of the above-mentioned imitation denim fabric, ultrasonic-assisted cations are used to modify polyester, and then the fabric is woven with weft OE pure polyester yarn after coating dyeing and post-processed to obtain the fabric. The denim fabric made by this method has a deep color because the polyester is dyed by coating dyeing, and the color difference is quite obvious from the color of PE pure polyester yarn, and the color transition is not natural enough. Summary of the invention

[0006] In order to reduce the color difference of imitation denim fabrics and present a dyeing effect with different shades and a more natural transition, the present application provides an imitation denim fabric and a preparation process thereof.

[0007] In a first aspect, the present application provides a process for preparing imitation denim fabric, which adopts the following technical solution: A preparation process of imitation denim fabric, weaving: using polylactic acid fiber pretreated by oxygen plasma as warp yarn and cotton fiber as weft yarn to weave to obtain grey cloth, wherein the percentage of cotton fiber to polylactic acid fiber is 70-75%:25-30%; Dyeing: Use indigo dye solution with a pH of 6-7 to pad-dye the grey cloth; Desizing: The dyed grey fabric is sequentially washed, oxidized, soaped, washed and dried to desize the grey fabric; Finishing: The desized grey fabric is finished by using fading treatment, shaping and pre-shrinking processes in sequence to produce imitation denim fabric.

[0008] By adopting the above technical scheme, cotton fiber is a natural fiber, mainly composed of cellulose, with good moisture absorption and air permeability, but its affinity with indigo dye is relatively small, and the dyeing rate is low, while polylactic acid fiber is a synthetic fiber, which is polymerized by lactic acid, and has good biodegradability and environmental protection. The molecular chain of polylactic acid fiber contains reactive functional groups, such as ester groups, which makes it have good reactivity with dyes, and the dyeing process is relatively simple, does not require complicated reduction and oxidation processes, and has a high dyeing rate and good dyeing fastness; since there are no strong polar groups in the molecular chain of polylactic acid fiber, there are more hydrophobic ester groups and equidistantly arranged methyl groups, which belongs to hydrophobic For water-based fibers, the polylactic acid fiber is first treated with oxygen plasma, which can improve its surface physical and chemical properties in a short time, increase surface roughness and hydrophilicity, facilitate the adsorption and diffusion of indigo dye solution on the fiber surface, thereby improving the dyeing rate, and oxygen plasma treatment can change the crystal structure of the fiber surface, increase the lattice constant, loosen the crystal structure, and also help the dye molecules penetrate into the fiber, further increasing the dyeing rate; finally, oxygen plasma treatment can introduce new functional groups on the surface of polylactic acid fibers, such as oxygen-containing functional groups such as hydroxyl groups, so as to react chemically with indigo dye, enhance the binding force between dye and fiber, improve the dyeing rate and improve color fastness. Therefore, polylactic acid fiber is used as warp yarn and cotton fiber is used as weft yarn, and dyeing is performed after weaving to obtain a denim-like fabric with natural transition and high breaking strength.

[0009] Optionally, the polylactic acid fiber comprises polylactic acid, poly 3-hydroxybutyrate-4-hydroxybutyrate and triacetin in a mass ratio of 6-7:3-4:4-5.

[0010] By adopting the above technical solution, polylactic acid has good biodegradability, but it also has certain disadvantages, such as the brittleness of pure polylactic acid, high fiber modulus, insufficient softness, and poor comfort. Poly 3-hydroxybutyrate-4-hydroxybutyrate (P34HB) is the fourth generation PHA. The introduction of 4-hydroxybutyrate monomers into the poly (3-hydroxybutyrate) molecular chain increases the softness of the chain and improves thermal stability. It also has a biodegradable effect. The addition of poly 3-hydroxybutyrate-4-hydroxybutyrate can play a toughening role, improve the brittleness of polylactic acid, and the resulting fiber has better elasticity, improved elastic recovery, and better shape retention. , which improves the softness of the fiber, makes it softer and smoother, reduces roughness and increases wear resistance. Triacetin is a plasticizer that can promote the movement of polylactic acid molecular chains, improve the crystallinity of polylactic acid, increase the crystallization rate, weaken the interaction between molecular chains, promote the movement of molecular chains and the slip between molecular chains, and increase the toughness of polylactic acid fibers. Moreover, triacetin not only acts as a plasticizer to increase the elasticity and toughness of the fiber, but also acts as an adhesive to make the contact parts between the fibers bond to each other or even fuse together, so that the entire fiber forms an overall network structure with significantly improved toughness and resilience.

[0011] Optionally, the polylactic acid fiber is made by the following method: The polylactic acid and poly 3-hydroxybutyrate-4-hydroxybutyrate are mixed and dried to a water content of less than 0.003%, triacetin is added, mixed, extruded, granulated, melt-spun, cooled, bundled, oiled, and stretched by 1.4-1.7 times to obtain initial fibers; The initial fibers are sequentially impregnated with an alkali solution and a chitosan solution, and then washed and dried respectively to obtain polylactic acid fibers.

[0012] By adopting the above technical solution, the initial fiber is impregnated with alkali solution, and sodium hydroxide can react with the initial polylactic acid fiber. Since the polylactic acid fiber macromolecule contains more ester bonds, in the presence of alkali, the ester group can be catalyzed to hydrolyze, generate corresponding acid and alcohol, and change the macromolecular chain, thereby increasing the number of active groups on the fiber surface and improving the reaction activity of the initial fiber. The increase of active groups on the initial fiber surface is conducive to its interaction with chitosan. Chitosan molecules contain multiple functional groups such as hydroxyl and amino groups, which can interact with the active groups on the initial fiber surface, such as hydrogen bonds, ionic bonds, etc. Therefore, the increase of active groups can make chitosan more easily attached to the initial fiber surface, thereby increasing the etching grooves on the fiber surface, making the fiber surface more uniform, flat, and smooth, with stronger resistance to external forces and improved breaking strength. In addition, the attachment of chitosan introduces active groups such as hydroxyl and amino groups, which improves hydrophilicity. When pad-dyed with indigo dye solution, the dyeing rate is higher.

[0013] Optionally, the cotton fiber is pretreated as follows: A quaternary ammonium carboxymethyl chitosan solution with a concentration of 5-7 g / L and a cation-modified nanocellulose crystal suspension with a concentration of 8-10 g / L are homogenized by ultrasound to prepare an impregnation solution, wherein the mass ratio of the cation-modified nanocellulose crystal to the quaternary ammonium carboxymethyl chitosan is 1:3-4; Add cotton fiber into the impregnation liquid with a bath ratio of 1:20-25, raise the temperature to 60-70°C, impregnate for 20-30 minutes, then perform double impregnation and double rolling, bake, wash and dry.

[0014] By adopting the above technical scheme, the quaternary ammonium carboxymethyl chitosan contains carboxyl groups. In the process of reacting with cotton fibers, the carboxyl groups are cross-linked with the cotton fibers to form chemical bonds, making the aggregation structure inside the cotton fiber molecules more compact, thereby improving the breaking strength and wear resistance of the cotton fibers. In addition, the quaternary ammonium carboxymethyl chitosan macromolecules are physically adsorbed and chemically bonded with the cellulose macromolecules, changing the internal structure of the fibers, and tightly bonding with the fibers, greatly limiting the free movement of the cellulose macromolecules, thereby preventing the relative slippage of the macromolecular chain segments of cellulose when subjected to external forces, enhancing its wrinkle recovery ability, and improving the wrinkle resistance of the fabric. The cationic modified nanocellulose crystals are evenly mixed with the quaternary ammonium carboxymethyl chitosan solution, and the cationic modified nanocellulose crystals are bonded to each other. A three-dimensional network structure is formed through hydrogen bonding to improve the strength of cotton fibers. When the two are used in a specific ratio, they are evenly distributed on the surface of cotton fibers and cross-linked with each other, which has a better effect on strengthening the strength of cotton fibers. In addition, quaternized carboxymethyl chitosan forms a film on the surface of cotton fibers to cover the active groups on the surface of cotton fibers, but it still contains hydroxyl groups and amino groups and can still be dyed with indigo dye solution. Cationic modified nanocellulose crystals have a similar chemical structure to cotton fibers, a large specific surface area, and carry some positive charges. There is a certain electrostatic repulsion with the indigo dye with a positive charge under weak acid conditions. Therefore, the cotton fibers are not completely dyed with indigo, and can form a slight color difference with the polylactic acid fibers with a better dyeing rate, obtaining a more natural gray transition effect.

[0015] Optionally, the oxygen pressure of the oxygen plasma pretreatment is 0.13-0.15 MPa, the vacuum degree is 90-100 Pa, the power is 240-250 W, and the treatment time is 120-180 s.

[0016] By adopting the above technical solution, under a specific pressure, oxygen plasma is used to treat the surface of the polylactic acid fiber to increase its surface roughness and hydrophilicity. At the same time, the crystal structure of the fiber can be loosened, which helps the dye molecules to penetrate into the fiber, facilitates the diffusion and adsorption of indigo dye, and improves the dyeing rate.

[0017] Optionally, the specific method of padding dyeing is: immersing the grey cloth in indigo dye solution, padding at room temperature, with a padding rate of 85-90%, then heating to 60°C at 2-4°C / min, keeping warm for 10-15min, then heating to 105°C at 1-2°C / min, keeping warm for 20-30min, and then cooling to room temperature at 2-4°C / min.

[0018] By adopting the above technical solution, as the temperature rises, the internal kinetic energy of the indigo dye liquid increases, the movement of the fiber molecular chain intensifies, the fiber structure becomes loose, and the dye can more easily enter the fiber, thereby improving the dyeing rate.

[0019] Optionally, the preparation method of the indigo dye solution is as follows: heat deionized water to 60-65°C, add 1.2-1.4g / L indigo dye, 5-6g / L sodium hydroxide, and 18-20g / L hydrosulfite, stir evenly and seal, reduce in a constant temperature water bath at 60-65°C, adjust the pH to 6-7 with glacial acetic acid, add 1-1.2g / L thiourea dioxide, 5-6g / L penetrant and 3-4g / L dispersant, mix evenly, and obtain the indigo dye solution.

[0020] By adopting the above technical scheme, due to the presence of a large number of ester bonds in the molecular structure of polylactic acid, polylactic acid fiber is not alkali-resistant and is easily hydrolyzed under wet, hot and alkaline conditions, resulting in quality loss and strength reduction of polylactic acid fiber. Therefore, this application uses a dye solution with a pH value of 6-7 for treatment to reduce the effect of the dye solution on the strength of polylactic acid fiber.

[0021] Optionally, the fading treatment uses sodium hypochlorite with a concentration of 3-6 g / L and sodium hydroxide with a concentration of 1-2 g / L, a temperature of 40-60° C., and a time of 8-15 min.

[0022] By adopting the above technical solution, the fading treatment can increase the softness of the fabric, making it softer and more delicate, and improving the wearing comfort. The washing and fading treatment increases environmental protection and reduces water pollution when the clothing is washed for the second time.

[0023] Optionally, the setting temperature is 98-102° C. and the time is 45-50 min.

[0024] By adopting the above technical solution, the dimensional stability of the imitation denim fabric during subsequent processing and use can be improved, the fabric can be prevented from being deformed due to external force, and the feel of the fabric can be improved, making it softer, reducing wrinkles, improving the overall texture, increasing wear resistance and strength, and facilitating the discharge of steam from the fabric fibers, thereby improving dyeing uniformity.

[0025] In a second aspect, the present application provides a denim-like fabric, which adopts the following technical solution: A denim-like fabric is produced by adopting the preparation process of the denim-like fabric.

[0026] By adopting the above technical scheme, cotton fiber is used as weft yarn, polylactic acid fiber pretreated by oxygen plasma is used as weft yarn, and dyeing is performed after weaving. The color transition of the imitation denim fabric is more natural, and it has good wear resistance, high breaking strength, good wrinkle recovery, and is not easy to produce creases.

[0027] In summary, this application has the following beneficial effects: 1. Since the present application uses polylactic acid fibers treated with oxygen plasma as warp yarns and cotton fibers as weft yarns, and the fabric is woven into grey cloth and then dyed with indigo dye solution, followed by desizing and post-treatment, the polylactic acid fibers pre-treated with oxygen plasma have a high adsorption capacity for indigo dye, while the cotton fibers have a low dyeing rate, thus presenting a uniform "gray" effect of varying shades, thereby producing a denim-like fabric with a more natural dyeing transition.

[0028] 2. In this application, poly 3-hydroxybutyrate-4-hydroxybutyrate is preferably used in combination with triacetin and polylactic acid as the raw material of polylactic acid fiber. Poly 3-hydroxybutyrate-4-hydroxybutyrate can improve the softness and roughness of polylactic acid fiber, making the imitation denim modulus softer and more comfortable, and having strong wear resistance. Triacetin can play a plasticizing role, improve the elasticity and toughness of the fiber, and increase the breaking strength of polylactic acid fiber.

[0029] 3. In the present application, it is preferred to use a mixture of a cationic modified nanocellulose crystal suspension and a quaternized carboxymethyl chitosan solution to pretreat the cotton fiber, which can improve the breaking strength and wear resistance of the cotton fiber, while making the cotton fiber and the polylactic acid fiber present a certain color difference, thereby obtaining a natural transition imitation denim fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a picture of the imitation denim fabric prepared in Example 1.

[0031] Figure 2 This is a picture of the imitation denim fabric prepared in Example 2. DETAILED DESCRIPTION

[0032] The following examples further illustrate the present application in detail.

[0033] Preparation Example 1-7 of Polylactic Acid Fiber In the following preparation examples, polylactic acid is selected from Nature Works, with a grade of 6202d, and the weight average molecular weight of poly 3-hydroxybutyrate-4-hydroxybutyrate is 2×10 5 g / mol, and the number average molecular weight is 9.4×10 4g / mol, the molar content of 4HBd is 9%, the deacetylation degree of chitosan is 95%, it is selected from Xi'an Wanfang Biotechnology, the product number is kjt, and the degreasing agent is selected from Vigor Textile Auxiliary Agents, the model is degreasing agent Lygal AK.

[0034] Preparation Example 1: (1) 70 g of polylactic acid and 30 g of poly 3-hydroxybutyrate-4-hydroxybutyrate were mixed uniformly, dried at 70° C. to a water content of less than 0.003%, 40 g of triacetin was added, mixed uniformly, extruded, and granulated to obtain blended slices, the granulation temperature being 200° C.; (2) The blended chips are melt-spun, air-cooled, bundled and oiled, and then stretched 1.4 times under a heat-stretching process of 80°C and a heat-setting process of 110°C to produce polylactic acid fibers. The spinning temperature is 240°C and the spinning speed is 800 m / min.

[0035] Preparation Example 2: (1) 60 g of polylactic acid and 40 g of poly 3-hydroxybutyrate-4-hydroxybutyrate were mixed uniformly, dried at 70° C. to a water content of less than 0.003%, 50 g of triacetin was added, mixed uniformly, extruded, and granulated to obtain blended slices, the granulation temperature being 200° C.; (2) The blended chips are melt-spun, air-cooled, bundled and oiled, and then stretched 1.7 times under a heat-stretching process of 80°C and a heat-setting process of 110°C to produce polylactic acid fibers. The spinning temperature is 240°C and the spinning speed is 800 m / min.

[0036] Preparation Example 3: The difference from Preparation Example 1 is that polylactic acid is used in an equal amount to replace poly 3-hydroxybutyrate-4-hydroxybutyrate.

[0037] Preparation Example 4: The difference from Preparation Example 1 is that polylactic acid is used in an equal amount to replace poly 3-hydroxybutyrate-4-hydroxybutyrate, and polylactic acid is used in an equal amount to replace triacetin.

[0038] Preparation Example 5: (1) 70 g of polylactic acid and 30 g of poly 3-hydroxybutyrate-4-hydroxybutyrate were mixed uniformly, dried at 70° C. to a water content of less than 0.003%, 40 g of triacetin was added, mixed uniformly, extruded, and granulated to obtain blended slices, the granulation temperature being 200° C.; (2) The blended chips are melt-spun, air-cooled, bundled and oiled, and then stretched 1.4 times under a heat-stretching process of 80°C and a heat-setting process of 110°C to produce initial fibers. The spinning temperature is 240°C and the spinning speed is 800 m / min.

[0039] (3) The initial fiber was immersed in an alkali solution containing soda ash and a degreaser, with a bath ratio of 1:20, a soda ash concentration of 7 g / L, and a degreaser concentration of 5 g / L, and then the temperature was raised to 80°C at 2°C / min, and after immersion for 40 min, the temperature was lowered to 50°C at 3°C / min, and then washed with water and dried at 60°C; (4) The initial fibers immersed in the alkali solution were immersed in a chitosan solution with a concentration of 1.5 wt% at 60°C for 8 h. The initial fibers were taken out, washed with water, and dried at 60°C to obtain polylactic acid fibers.

[0040] Preparation Example 6: The difference from Preparation Example 5 is that the initial fibers are not immersed in alkali solution, but are directly immersed in the chitosan solution.

[0041] Preparation Example 7: The difference from Preparation Example 5 is that the initial fibers are not impregnated with chitosan solution, but are impregnated with alkali solution, washed with water, and dried to produce polylactic acid fibers. Example

[0042] Embodiment 1: A process for preparing a denim-like fabric, comprising the following steps: S1. Weaving: Cotton fiber is used as weft yarn and polylactic acid fiber pretreated by oxygen plasma is used as warp yarn to weave a 200 g / m 2 The grey cloth, the percentage of cotton fiber and polylactic acid fiber is 75%:25%, the oxygen pressure of the polylactic acid fiber pretreated with oxygen plasma is 0.15MPa, the vacuum degree is 100Pa, the power is 250W, the treatment time is 180s, and the polylactic acid fiber is made by Preparation Example 1.

[0043] S2. Dyeing: heat deionized water to 60°C, add 1.2 g / L indigo dye, 6 g / L sodium hydroxide and 20 g / L hydrosulfite, stir well and seal, reduce in a constant temperature water bath at 60°C, adjust pH to 6 with glacial acetic acid, add 1.2 g / L thiourea dioxide, 6 g / L penetrant and 4 g / L penetrant, mix well to obtain indigo dye solution; immerse the blank in the indigo dye solution with a bath ratio of 1:25, roll at room temperature, with a rolling rate of 85%, then heat to 60°C at 2°C / min, keep warm for 15 min, then heat to 105°C at 1°C / min, keep warm for 30 min, then cool to room temperature at 2°C / min, the penetrant is selected from Jiangsu Hai'an Petrochemical, model JFC-E, and the dispersant is selected from Jinan Yueyang New Materials, item number NNO.

[0044] S3, desizing: the dyed grey cloth is sequentially washed, oxidized (5 minutes at room temperature, this is one time, repeated immersion 5 times), soap washed (soap powder 2g / L, 95℃ soap boiling for 20min), washed and dried.

[0045] S4. Finishing: The desized grey cloth is finished by fading treatment, shaping and pre-shrinking processes. The fading treatment uses 6 g / L sodium hypochlorite and 2 g / L sodium hydroxide at a temperature of 60°C for 8 min and a shaping temperature of 98°C for 45 min to obtain imitation denim fabric.

[0046] Embodiment 2: A process for preparing a denim-like fabric, comprising the following steps: S1. Weaving: Cotton fiber is used as weft yarn and polylactic acid fiber pretreated by oxygen plasma is used as warp yarn to weave a 200 g / m 2 The grey cloth, the percentage of cotton fiber and polylactic acid fiber is 70%:30%, the oxygen pressure of the polylactic acid fiber pretreated with oxygen plasma is 0.13MPa, the vacuum degree is 90Pa, the power is 240W, the treatment time is 120s, and the polylactic acid fiber is made by Preparation Example 2.

[0047] S2, dyeing: deionized water is heated to 65°C, 1.4 g / L indigo dye, 5 g / L sodium hydroxide and 18 g / L hydrosulfite are added, the mixture is stirred evenly and sealed, reduced in a constant temperature water bath at 65°C, the pH is adjusted to 7 with glacial acetic acid, 1 g / L thiourea dioxide, 5 g / L penetrant and 3 g / L penetrant are added, and the mixture is mixed evenly to obtain an indigo dye solution; the blank is placed in the indigo dye solution and immersed in the indigo dye solution, the bath ratio is 1:20, and the blank is rolled at room temperature, the rolling rate is 90%, and then the temperature is increased to 60°C at 4°C / min, kept warm for 10 min, then the temperature is increased to 105°C at 2°C / min, kept warm for 20 min, and then cooled to room temperature at 4°C / min. The penetrant is selected from Jiangsu Hai'an Petrochemical, model JFC-E, and the dispersant is selected from Jinan Yueyang New Materials, item number NNO.

[0048] S3, desizing: the dyed grey cloth is sequentially washed, oxidized (5 minutes at room temperature, this is one time, repeated immersion 5 times), soap washed (soap powder 2g / L, 95℃ soap boiling for 20min), washed and dried.

[0049] S4. Finishing: The desized grey cloth is finished by fading treatment, shaping and pre-shrinking processes. The fading treatment uses 3 g / L sodium hypochlorite and 1 g / L sodium hydroxide at a temperature of 40°C for 15 min and a shaping temperature of 102°C for 40 min to obtain imitation denim fabric.

[0050] Embodiment 3: A process for preparing a denim-like fabric, comprising the following steps: S1. Weaving: Cotton fiber is used as weft yarn and polylactic acid fiber pretreated by oxygen plasma is used as warp yarn to weave a 200 g / m 2The grey cloth, the percentage of cotton fiber and polylactic acid fiber is 73%:27%, the oxygen pressure of the polylactic acid fiber pretreated with oxygen plasma is 0.14MPa, the vacuum degree is 95Pa, the power is 240W, the treatment time is 160s, and the polylactic acid fiber is made by Preparation Example 1.

[0051] S2, dyeing: deionized water is heated to 63 ° C, 1.3 g / L of indigo dye, 5.5 g / L of sodium hydroxide and 19 g / L of hydrosulfite are added, the mixture is stirred evenly and sealed, reduced in a constant temperature water bath at 63 ° C, the pH is adjusted to 6.5 with glacial acetic acid, 1.1 g / L of thiourea dioxide, 5.5 g / L of penetrant and 3.5 g / L of penetrant are added, and the mixture is mixed evenly to obtain an indigo dye solution; the blank is placed in the indigo dye solution and immersed in the indigo dye solution with a bath ratio of 1:30, and rolled at room temperature with a rolling rate of 90%, and then the temperature is raised to 60 ° C at 3 ° C / min, kept warm for 13 min, and then the temperature is raised to 105 ° C at 1 ° C / min, kept warm for 25 min, and then cooled to room temperature at 3 ° C / min. The penetrant is selected from Jiangsu Hai'an Petrochemical, model JFC-E, and the dispersant is selected from Jinan Yueyang New Materials, item number NNO.

[0052] S3, desizing: the dyed grey cloth is sequentially washed, oxidized (5 minutes at room temperature, this is one time, repeated immersion 5 times), soap washed (soap powder 2g / L, 95℃ soap boiling for 20min), washed and dried.

[0053] S4. Finishing: The desized grey cloth is finished by fading treatment, shaping and pre-shrinking processes. The fading treatment uses 4 g / L sodium hypochlorite and 1.5 g / L sodium hydroxide at a temperature of 50°C for 12 min and a shaping temperature of 100°C for 50 min to obtain imitation denim fabric.

[0054] Example 4: A preparation process of imitation denim fabric, which is different from Example 1 in that the polylactic acid fiber is made from Preparation Example 3.

[0055] Example 5: A process for preparing imitation denim fabric, which is different from Example 1 in that the polylactic acid fiber is prepared from Preparation Example 4.

[0056] Example 6: A process for preparing imitation denim fabric, which is different from Example 1 in that the polylactic acid fiber is made from Preparation Example 5.

[0057] Example 7: A process for preparing imitation denim fabric, which is different from Example 5 in that the polylactic acid fiber is prepared from Preparation Example 6.

[0058] Example 8: A process for preparing imitation denim fabric, which is different from Example 5 in that the polylactic acid fiber is made from Preparation Example 7.

[0059] Embodiment 9: A process for preparing a denim-like fabric, which is different from Embodiment 5 in that the cotton fiber used as the weft yarn is pretreated as follows: Cationic modified nanocellulose crystal suspension: Nanocellulose crystals were placed in acetate buffer (pH 5), 0.4 U / mL laccase and 1.4 mg / mL 2,2,6,6-tetramethylpiperidine were added, and the mixture was reacted at 50°C for 12 h to obtain oxidized cellulose nanocrystals, and then Girardt's reagent was added at a mass ratio of 1:20 to the nanocellulose crystals. After the reaction was continued for 6 h, the reaction solution was dialyzed until the conductivity remained unchanged, and a cationic modified nanocellulose crystal suspension with a concentration of 10 g / L was obtained by dilution. The cellulose nanocrystals were selected from Xi'an Qiyue Biotechnology Co., Ltd., and the model was CNC; Quaternized carboxymethyl chitosan solution: 2g carboxymethyl chitosan was added to anhydrous ethanol, 4g 2,3-propyltrimethylammonium chloride and 3ml distilled water were added, and the mixture was reacted at 80°C for 4h, and then 4g 2,3-propyltrimethylammonium chloride and 3ml distilled water were added. Anhydrous ethanol was added to allow the product to fully settle, and the precipitate was washed with anhydrous ethanol, filtered, and dried at 60°C to obtain quaternized carboxymethyl chitosan. 7g quaternized carboxymethyl chitosan was taken, distilled water was added, and a quaternized carboxymethyl chitosan solution of 7g / L was prepared. The carboxymethyl chitosan was selected from Xi'an Prius Biotechnology Co., Ltd., and the product number was PRS240527. A quaternary ammonium carboxymethyl chitosan solution with a concentration of 7 g / L was mixed with a cation-modified nanocellulose crystal suspension with a concentration of 10 g / L, and ultrasonically homogenized to prepare an impregnation solution, wherein the mass ratio of the cation-modified nanocellulose crystal to the quaternary ammonium carboxymethyl chitosan was 1:4; Add cotton fiber to the impregnation liquid with a bath ratio of 1:25, raise the temperature to 70°C, impregnate for 20 minutes, then perform double dipping and double rolling, pre-dry at 80°C for 5 minutes, bake at 160°C for 2.5 minutes, wash with water, and dry at 60°C.

[0060] Embodiment 10: A process for preparing a denim-like fabric, which is different from Embodiment 5 in that the cotton fiber used as the weft yarn is pretreated as follows: Cationic modified nanocellulose crystal suspension: Nanocellulose crystals were placed in acetate buffer (pH 5), 0.4 U / mL laccase and 1.4 mg / mL 2,2,6,6-tetramethylpiperidine were added, and the mixture was reacted at 50°C for 12 h to obtain oxidized cellulose nanocrystals, and then Girardt's reagent was added at a mass ratio of 1:20 to the nanocellulose crystals. After the reaction was continued for 6 h, the reaction solution was dialyzed until the conductivity remained unchanged, and a cationic modified nanocellulose crystal suspension with a concentration of 8 g / L was obtained by dilution. The cellulose nanocrystals were selected from Xi'an Qiyue Biotechnology Co., Ltd., and the model was CNC; Quaternized carboxymethyl chitosan solution: add 2g carboxymethyl chitosan to anhydrous ethanol, add 4g 2,3-propyltrimethylammonium chloride and 3ml distilled water, react at 80°C for 4h, then add 4g 2,3-propyltrimethylammonium chloride and 3ml distilled water, add anhydrous ethanol to fully precipitate the product, wash the precipitate with anhydrous ethanol, filter, and dry at 60°C to obtain quaternized carboxymethyl chitosan, take 5g quaternized carboxymethyl chitosan, add distilled water, and prepare a quaternized carboxymethyl chitosan solution of 5g / L. The carboxymethyl chitosan is selected from Xi'an Preus Biotechnology, and the product number is PRS240527; A quaternary ammonium carboxymethyl chitosan solution with a concentration of 5 g / L was mixed with a cation-modified nanocellulose crystal suspension with a concentration of 8 g / L, and ultrasonically homogenized to prepare an impregnation solution, wherein the mass ratio of the cation-modified nanocellulose crystal to the quaternary ammonium carboxymethyl chitosan was 1:3; Add cotton fiber to the impregnation liquid with a bath ratio of 1:20, raise the temperature to 60°C, impregnate for 30 minutes, then perform double dipping and double rolling, pre-dry at 70°C for 10 minutes, bake at 150°C for 5 minutes, wash with water, and dry at 70°C.

[0061] Example 11: A process for preparing imitation denim fabric, which is different from Example 10 in that an equal amount of cationic modified nanocellulose crystal suspension is used to replace the quaternized carboxymethyl chitosan solution.

[0062] Example 12: A process for preparing imitation denim fabric, which is different from Example 10 in that an equal amount of carboxymethyl chitosan solution is used to replace the quaternized carboxymethyl chitosan solution.

[0063] Example 13: A process for preparing a denim-like fabric, which is different from Example 10 in that an equal amount of distilled water is used to replace the quaternized carboxymethyl chitosan solution.

[0064] Comparative Example Comparative Example 1: A preparation process of a denim-like fabric, which differs from Example 1 in that an equal amount of cotton fiber is used instead of polylactic acid fiber, that is, cotton fiber pretreated with oxygen plasma is used as the warp, the oxygen pressure of the oxygen plasma treatment is 0.15 MPa, the vacuum degree is 100 Pa, the power is 250 W, and the treatment time is 180 s.

[0065] Comparative Example 2: A process for preparing a denim-like fabric, which differs from Example 1 in that an equal amount of polylactic acid fibers are used instead of cotton fibers as warp yarns.

[0066] Comparative Example 3: A preparation process of a denim-like fabric, comprising the following steps: using 75% and 25% polyester and spandex as warp and weft yarns respectively, dyeing the polyester with indigo, the indigo dye solution is the same as that in Example 1, and the bath ratio during dyeing is 1:20, padding at room temperature, the padding rate is 90%, then heating to 60°C at 4°C / min, keeping warm for 10 minutes, then heating to 105°C at 2°C / min, keeping warm for 20 minutes, then cooling to room temperature at 4°C / min, the weft yarn keeps natural color, and then weaving to obtain a 200g / m 2 The dyed cloth is desized and finished to obtain a denim-like fabric, and the desizing and finishing are the same as those in Example 1.

[0067] Performance testing Imitation denim fabrics were prepared according to the methods in the examples and comparative examples, and various parameters were tested according to the following methods. The test results are recorded in Table 1.

[0068] 1. Dyeing rate: Use UV-2600 ultraviolet-visible spectrophotometer to test the absorbance of the dyeing solution and the residual liquid after dyeing at the maximum absorption wavelength, and calculate the dyeing rate according to the following formula: Dyeing rate = (A0-A1) / A0×100%, where A0 is the absorbance of the dyeing solution at the maximum absorption wavelength, and A1 is the absorbance of the dyeing residual liquid at the maximum absorption wavelength.

[0069] 2. Abrasion resistance: Use YG402C-13 fabric flat grinding instrument to test in accordance with GB / T4802.2-2008. Cut 4 samples with a diameter of 38 mm. Use 150-mesh sandpaper as the abrasive and 595 g as the pressure weight. Abrade the fabric several times until it is worn out.

[0070] 3. Breaking strength: Use a multifunctional fabric strength tester and refer to GB / T3923.1-2013 "Tensile properties of textile fabrics Part 1: Breaking strength and elongation at break strip method" for testing.

[0071] 4. Wrinkle resistance: Use YG541E laser plant wrinkle elasticity tester to test in accordance with GB / T3819-1997. Cut convex specimens, 5 pieces in radial and latitudinal directions. The specimens are not ironed and must be placed horizontally for 24 hours before they can be used for testing.

[0072] Table 1 Performance test of imitation denim fabrics Combining the data in Table 1 with the preparation processes of Examples 1-3, it can be seen that the imitation denim fabrics prepared in this way have a good dyeing rate, making the color transition more natural, and have good wear resistance, high breaking strength, stretch resistance, tear resistance, and good anti-wrinkle effect.

[0073] In Example 4, the polylactic acid fiber prepared in Preparation Example 3 was used. Compared with Preparation Example 1, poly 3-hydroxybutyrate-4-hydroxybutyrate was not added. It can be seen that although the breaking strength of the imitation denim fabric is increased, the wear resistance is weakened, the wrinkle resistance is reduced, and the elongation at break is reduced, indicating that the addition of poly 3-hydroxybutyrate-4-hydroxybutyrate can improve the surface smoothness of the polylactic acid fiber and enhance its wrinkle resistance.

[0074] In Example 5, the polylactic acid fiber prepared in Preparation Example 4 was used. Compared with Example 1, poly 3-hydroxybutyrate-4-hydroxybutyrate and triacetin were not added. It can be seen that the wear resistance and wrinkle resistance of the imitation denim fabric are reduced.

[0075] In Example 6, the polylactic acid fiber prepared in Preparation Example 5 was used, and the fiber was also soaked in alkali solution and impregnated with chitosan solution. The dyeing rate of the imitation denim fabric was increased, and the wear resistance was enhanced, the breaking strength and breaking elongation were increased, and the anti-wrinkle recovery effect was improved.

[0076] Compared with Example 5, Example 7 did not impregnate the initial fibers with alkali solution, while Example 8 did not impregnate the initial fibers with chitosan solution. It can be seen from the data in Table 1 that the dyeing rate, abrasion resistance, tensile strength and wrinkle recovery ability of the imitation denim fabrics prepared in Examples 7 and 8 were all reduced.

[0077] Compared with Example 5, Examples 9 and 10 further use quaternized carboxymethyl chitosan and cationic modified nanocellulose crystals to treat the cotton fibers. The imitation denim fabrics prepared in Examples 9 and 10 have enhanced wear resistance, increased tensile and tear resistance, and improved wrinkle recovery capabilities.

[0078] In Example 11, compared with Example 10, the quaternary ammonium carboxymethyl chitosan solution was replaced by an equal amount of cationic modified nanocellulose crystal solution, and it can be seen that the wear resistance and other capabilities of the imitation denim fabric were slightly reduced; in Example 12, the quaternary ammonium carboxymethyl chitosan solution was replaced by an equal amount of carboxymethyl chitosan solution, and compared with Example 10, the various properties of the imitation denim fabric were reduced, and the decline was greater than that in Example 11; in Example 13, distilled water was used to replace the quaternary ammonium carboxymethyl chitosan solution, and it can be seen that the wear resistance and other detection effects of the imitation denim fabric prepared in Example 13 were reduced more.

[0079] Comparative Example 1 uses cotton fibers pretreated with oxygen plasma as warp yarns. From the data in Table 1, it can be seen that the imitation denim fabric prepared in Comparative Example 1 has a low dyeing rate and reduced wear resistance. It also has poor wrinkle recovery and reduced tensile tear resistance.

[0080] In Comparative Example 2, polylactic acid fiber is used in equal amounts to replace cotton fiber as warp yarn. It can be seen that the dyeing rate is too high and the gray effect cannot be achieved.

[0081] Comparative Example 3 uses polyester and spandex as warp and weft yarns respectively, the warp yarns are dyed and woven with the weft yarns, and the imitation denim fabric is prepared by desizing and post-treatment. The performance of the imitation denim fabric is not as good as that of the imitation denim fabric prepared in Examples 1-3.

[0082] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A process for preparing imitation denim fabric, characterized in that: The following steps are involved: Weaving: using the polylactic acid fiber pretreated by oxygen plasma as the warp yarn and the cotton fiber as the weft yarn to weave a grey cloth, wherein the percentage of cotton fiber to polylactic acid fiber is 70-75%:25-30%; Dyeing: Use indigo dye solution with a pH of 6-7 to pad-dye the grey cloth; Desizing: The dyed grey fabric is sequentially washed, oxidized, soaped, washed and dried to desize the grey fabric; Finishing: The desized grey fabric is finished by using fading treatment, shaping and pre-shrinking processes in sequence to produce imitation denim fabric.

2. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The polylactic acid fiber comprises polylactic acid, poly 3-hydroxybutyrate-4-hydroxybutyrate and triacetin in a mass ratio of 6-7:3-4:4-5.

3. The process for preparing the imitation denim fabric according to claim 2, characterized in that: The polylactic acid fiber is made by the following method: The polylactic acid and poly 3-hydroxybutyrate-4-hydroxybutyrate are mixed and dried to a water content of less than 0.003%, triacetin is added, mixed, extruded, granulated, melt-spun, cooled, bundled, oiled, and stretched by 1.4-1.7 times to obtain initial fibers; The initial fibers are sequentially impregnated with an alkali solution and a chitosan solution, and then washed and dried respectively to obtain polylactic acid fibers.

4. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The cotton fibers are pretreated as follows: A quaternary ammonium carboxymethyl chitosan solution with a concentration of 5-7 g / L and a cation-modified nanocellulose crystal suspension with a concentration of 8-10 g / L are homogenized by ultrasound to prepare an impregnation solution, wherein the mass ratio of the cation-modified nanocellulose crystal to the quaternary ammonium carboxymethyl chitosan is 1:3-4; Add cotton fiber into the impregnation liquid with a bath ratio of 1:20-25, raise the temperature to 60-70°C, impregnate for 20-30 minutes, then perform double impregnation and double rolling, bake, wash and dry.

5. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The oxygen pressure of the oxygen plasma pretreatment is 0.13-0.15 MPa, the vacuum degree is 90-100 Pa, the power is 240-250 W, and the treatment time is 120-180 s.

6. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The specific method of padding dyeing is: immersing the grey cloth in indigo dye solution, padding at room temperature, with a padding rate of 85-90%, then heating to 60°C at 2-4°C / min, keeping warm for 10-15min, then heating to 105°C at 1-2°C / min, keeping warm for 20-30min, and then cooling to room temperature at 2-4°C / min.

7. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The preparation method of the indigo dye solution is as follows: heating deionized water to 60-65° C., adding 1.2-1.4 g / L indigo dye, 5-6 g / L sodium hydroxide, and 18-20 g / L hydrosulfite, stirring evenly and sealing, reducing in a constant temperature water bath at 60-65° C., adjusting the pH to 6-7 with glacial acetic acid, adding 1-1.2 g / L thiourea dioxide, 5-6 g / L penetrant and 3-4 g / L dispersant, mixing evenly, and preparing the indigo dye solution.

8. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The fading treatment uses sodium hypochlorite with a concentration of 3-6 g / L and sodium hydroxide with a concentration of 1-2 g / L, a temperature of 40-60° C., and a time of 8-15 minutes.

9. The process for preparing the imitation denim fabric according to claim 1, characterized in that: The setting temperature is 98-102° C. and the time is 45-50 minutes.

10. A denim-like fabric, characterized in that: The imitation denim fabric is made by the preparation process of the imitation denim fabric according to any one of claims 1 to 9.

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