An organic plant dye direct injection digital printing process for polyamide fabric

Abstract

The invention discloses an organic plant dye nylon direct-jet digital printing process, which belongs to the technical field of digital printing of fabrics. The process comprises the following steps: preparing pretreatment pulp→sizing fabric→drying I→preparing organic plant dye ink→digital printing→drying II→steaming→washing I→soap washing→washing II→drying III; the pretreatment pulp comprises the following components by mass percentage: 2-5% of guar gum, 0.5-2% of modified chitosan, 3-5% of ammonium tartrate, 3-5% of urea, 0-1% of pH regulator, and the balance is water; the pH value of the pretreatment pulp is 5-6; the organic plant dye ink comprises the following components by mass percentage: 3-12% of organic plant dye, 15-30% of moisturizing agent, 0-1% of solubilizing agent, 0.1-1% of surfactant, 0-1% of pH regulator, and the balance is deionized water; the pH value of the organic plant dye ink is 4-5.2. The printed nylon prepared by the process of the invention has the advantages of high K / S value, high color fixation rate, high color fastness, high clarity and good fabric feel.

Description

Technical Field

[0001] The invention belongs to the technical field of digital fabric printing, and in particular relates to a nylon direct-jet digital printing process with organic plant dyes. Background Art

[0002] In recent years, with the development of related technologies such as computers, materials, information and precision machinery manufacturing, inkjet printing technology has received more and more attention from people, and textile inkjet printing technology has gradually been formed. Inkjet printing has the advantages of high image quality, simple process flow, low production cost, and green environmental protection. This technology uses scanners, digital cameras and other means to input the pattern to be printed in digital form into the computer. After being processed by image software, the ink with pigment is controlled by the computer according to the design requirements, driven by compressed air, and sprayed onto the printed substrate through the nozzle of the inkjet printer to present the required pattern. Compared with traditional printing, it can print any pattern without considering the pattern type and number of colors, and does not require plate making. It can be produced quickly and is suitable for small batches or customized printing products.

[0003] Nylon is a polyamide fiber with the advantages of strength, good wear resistance, excellent elasticity and elastic recovery, and light weight, but it feels hard, so it is suitable for making outdoor lightweight clothing or equipment such as mountaineering clothes. The molecule of nylon is mainly composed of three parts: the hydrophobic methylene part, the hydrophilic amide bridge, and the amino and carboxyl groups at the chain end. However, the amino dyeing seat at the end only accounts for 1 / 10 of the amino content of wool. When printing with inkjet printing, it is easy to have problems such as low coloring rate, poor ink penetration uniformity, and low color fastness. Natural plant dyes have a long history of application. Although they have been replaced with the emergence of modern synthetic dyes, natural plant dyes have the natural advantages of safety and environmental protection and are still used in high-end clothing and high-end cosmetics. For natural dyes, they have more hydroxyl groups and strong hydrophilicity. When used for dyeing hydrophobic nylon fibers, there are problems such as low color fixation rate, low color fastness, and poor clarity. Therefore, the pretreatment process of the fabric is indispensable. In fact, the use of organic plant dyes for nylon inkjet printing technology has strict requirements on the preparation of dyes and the pretreatment of fabrics. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a nylon direct-jet digital printing process with organic plant dyes. By using organic plant dye ink and pretreatment pulp with a specific mass percentage, the nylon is first pretreated and then digitally printed, so that a nylon digitally printed fabric with high clarity, good color fixation rate and color fastness, and good feel can be obtained.

[0005] The technical scheme for achieving the purpose of the present invention is as follows: A nylon direct-injection digital printing process of organic plant dyes comprises the following steps:

[0006] Preparation of pretreatment pulp → fabric sizing → drying I → preparation of organic plant dye ink → digital printing → drying II → steaming → washing I → soap washing → washing II → drying III;

[0007] The pretreated pulp comprises the following components by mass percentage: 2-5% guar gum, 0.5-2% modified chitosan, 3-5% ammonium tartrate, 3-5% urea, 0-1% pH regulator, and the balance is water; the modified chitosan is chitosan modified by citric acid and quaternary ammonium salt; the pH value of the pretreated pulp is 5-6.

[0008] The viscosity of the guar gum is 50 to 5500 mPa·s, and preferably, the viscosity of the guar gum is 300 to 700 mPa·s.

[0009] The organic plant dye ink comprises the following components by mass percentage: 3-12% organic plant dye, 15-30% moisturizer, 0-1% solubilizer, 0.1-1% surfactant, 0-1% pH regulator, and the balance is deionized water; the pH value of the organic plant dye ink is 4-5.2.

[0010] The preparation method of the modified chitosan is as follows:

[0011] S1. Dissolve chitosan in acetic acid solution, stir under heating conditions until dissolved, add hydrogen peroxide solution dropwise, heat and stir for a period of time, add sodium hydroxide solution after cooling, adjust the pH of the system to alkaline, obtain the oligosaccharide chitosan sample after filtration, and dry it for later use.

[0012] Optionally, the mass fraction of the acetic acid solution is 2%, the mass fraction of the hydrogen peroxide solution is 1-3%, the heating temperature is 80-100°C, and the heating stirring time is 0.25-2h; the concentration of the sodium hydroxide solution is 4-6mol / L, and the drying temperature is 40-60°C; the sodium hydroxide solution adjusts the system pH to 10; the weight average molecular weight of the oligomolecular chitosan is 10000-100000, and preferably, the weight average molecular weight of the oligomolecular chitosan is 20000-50000.

[0013] S2. Dissolve citric acid and sodium hypophosphite in deionized water, add oligomolecular chitosan in batches, and react at 60-80°C for 2-4 hours with continuous stirring after complete dissolution. After the reaction is completed, cool to room temperature, precipitate with ethanol, wash, filter, and freeze-dry to obtain citric acid chitosan for use.

[0014] Optionally, the ethanol is an 85% ethanol solution; the freeze-drying temperature is -50 to -30°C; the molar mass ratio of the citric acid to the sodium hypophosphite is 10:1; and the mass ratio of the citric acid to the chitosan is (2 to 3):1.

[0015] S3. Dissolve citric acid chitosan in deionized water, add methanol or ethanol and anhydrous hydrogen chloride, and stir the reaction at 40-60°C for 6-12 hours. After the reaction, remove all solvents by vacuum distillation to obtain citric acid chitosan, which is freeze-dried for later use.

[0016] Optionally, the mass ratio of citric acid chitosan to methanol or ethanol is 1:(3-10); and the freeze-drying temperature is -50--30°C.

[0017] S4. Mix citrate chitosan and 2,3-epoxypropyltrimethylammonium chloride in deionized water, stir and react at 70-90°C for 6-10 hours, add sodium hydroxide solution to adjust the pH value to 8-9 and continue the reaction for 4-6 hours. After cooling, adjust the pH value to 5-6 with hydrochloric acid; then precipitate and wash the solution with ethanol, filter and dry to obtain modified chitosan.

[0018] Optionally, the concentration of the sodium hydroxide solution is 1 mol / L; the concentration of the hydrochloric acid is 1-2 mol / L; and the mass ratio of citrate chitosan to 2,3-epoxypropyltrimethylammonium chloride is 1:(1.5-3).

[0019] Preferably, the surface tension of the organic plant dye ink is 20 to 50 mN / m; the conductivity of the organic plant dye ink is 750 to 3000 μS / cm; and the viscosity of the organic plant dye ink is 2 to 8 mPa·s.

[0020] The solubilizing agent is selected from one or more of polyethylene glycol and N-methylpyrrolidone; the surfactant is selected from one or more of dioctyl sodium succinate, sodium N-oleoyl polypeptide, benzalkonium chloride, alkyl trimethyl ammonium chloride, alkyl trimethyl ammonium bromide, N-alkyl betaine, and alkylphenol polyoxyethylene ether; the humectant is selected from one or more of ethanol, diethylene glycol, ethylene glycol, and glycerol; the acidity regulator is one or more of acetic acid, hydrochloric acid, sulfuric acid, oxalic acid, triethanolamine, methylethanolamine, trimethylamine, and isopropanolamine.

[0021] The colors of the organic plant dye include red, yellow, blue and black. The red organic plant dye is derived from one or more of sappan wood, peanut skin, madder, safflower, saffron, purple-leaved sorrel, apple blossom, cherry blossom, onion and red yeast rice; the yellow organic plant dye is derived from one or more of coptis chinensis, turmeric, rhubarb, rehmannia root, jujube, sappan wood, sophora japonica flower, gardenia, sedge grass, green grass, phellodendron, oak, pomegranate, astringent persimmon, turmeric, walnut, mulberry, onion, safflower yellow and red yeast rice; the blue organic plant dye is derived from one or more of gardenia blue, indigo, indigo, indigo, woad, indigo and indigo; the black organic plant dye is derived from one or more of terminalia chebula, gallnut, water chestnut, Chinese tallow tree, rhus chinensis, koreana and chemysalacia styracifolia.

[0022] The preparation method of the pretreated pulp is: first add urea to deionized water and stir thoroughly; then add ammonium tartrate and stir thoroughly; finally add guar gum and modified chitosan, add a pH regulator to adjust the pH to 5-6, stir for 2 hours and then stand for 24 hours.

[0023] The fabric sizing step is: completely immersing the nylon fabric in the slurry, taking out the nylon fabric after a period of time, using a rolling car to remove excess slurry, using a double immersion and double rolling method, drying and shaping immediately after rolling, and taking out and storing in a sealed bag.

[0024] The preparation method of the organic plant dye ink is as follows: weigh a certain mass fraction of the organic plant dye, add a solubilizer, a surfactant, a humectant, a pH regulator and deionized water, stir thoroughly until the dye is fully dissolved, ultrasonicate for a period of time to make the dye more evenly distributed in the system, and filter the prepared ink first with a 0.45 μm aqueous filter membrane and then with a 0.22 μm aqueous filter membrane.

[0025] The temperature of the drying I is 80-120°C; the temperature of the drying II is 65-105°C; the temperature of the drying III is 100-120°C; the steaming temperature is 100-105°C, the state is saturated steam at normal pressure, and the time is 10-30 minutes.

[0026] The soap washing uses 1-2 g / L of standard soap flakes, a temperature of 90-100° C., and a washing time of 8-12 min; the water washing I is a warm water washing at 35-45° C. for 4-6 min; the water washing II is a warm water washing at 35-45° C. for 4-6 min, followed by a cold water washing for 4-6 min: the water bath ratios of the soap washing, water washing I, and water washing II are all 40:1-20:1.

[0027] Beneficial Effects

[0028] The present invention has the following beneficial effects:

[0029] The organic plant dye nylon direct-jet digital printing process provided by the present invention comprises the following steps: adding modified chitosan to the pretreatment slurry, wherein citric acid and quaternary ammonium salt are grafted to the amino and hydroxyl sites of the modified chitosan, respectively; after pretreatment of the nylon fabric, the pretreatment slurry covers the fiber surface and fills between the fibers at the same time; under weakly acidic conditions, the carboxyl groups on the modified chitosan and the amino groups on the nylon are combined by electrostatic action to achieve uniform dispersion; and the quaternary ammonium salt on the modified chitosan molecular chain provides more dyeing sites for the nylon, and combines with the organic plant dye with negative charge by ionic bonds, thereby ensuring uniform dispersion of the dye molecules, improving the dye fixation rate, reducing floating color, and preventing the ink from entering the fiber before steaming, thereby ensuring the clarity of the pattern outline. After steaming, the organic plant dye molecules enter the fiber under the action of high temperature for color fixation; at the same time, the chitosan, citric acid, and quaternary ammonium salt in the modified chitosan in the pretreatment slurry have a loosening and swelling effect on the fabric, which can make the stiff nylon fabric soft, thereby improving the fabric feel. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Infrared spectra of chitosan, citric acid chitosan and modified chitosan. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0033] The raw materials and equipment used in the embodiments and comparative examples are described as follows:

[0034] Guided belt digital printing machine: Model DTBS-1638, purchased from Chengdu Jinzhida Digital Technology Co., Ltd.;

[0035] Nylon fabric: nylon plain cloth, yarn count 4040, 180g, purchased from Haining Baichuang Textile Co., Ltd.;

[0036] Organic vegetable dyes:

[0037] Red: Monascus red pigment, color value 150, purchased from Guangdong Kelong Biotechnology Co., Ltd.;

[0038] Yellow: Monascus yellow pigment, color value 100, purchased from Guangdong Kelong Biotechnology Co., Ltd.;

[0039] Blue: Gardenia blue pigment, Natural 0004 dark blue, purchased from Changzhou Meisheng Biomaterials Co., Ltd.;

[0040] Black: Terminalia chebula and Galla chinensis black pigment, Natural 0018 black, purchased from Changzhou Meisheng Biomaterials Co., Ltd.;

[0041] Standard soap flakes: International standard soap powder, purchased from Standard Group Co., Ltd.;

[0042] Guar gum 1: 350-700 mPa.s; product number R1513-1, purchased from Nanjing Dulai Biotechnology Co., Ltd.;

[0043] Guar gum 2: 50 mPa.s; product number C400939, purchased from Shanghai Ketuo Chemical Technology Co., Ltd.;

[0044] Guar gum 3: 5000-5500 mPa.s; product number B607827, purchased from Shanghai Boer Chemical Reagent Co., Ltd.;

[0045] Ammonium tartrate: analytical grade, purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0046] Urea: analytical grade, purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd.;

[0047] Moisturizer: a mixture of ethanol, diethylene glycol and glycerol in a mass ratio of 2:1:1; ethanol, diethylene glycol and glycerol were all analytically pure and purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0048] Surfactant: OP-10; octylphenol polyoxyethylene ether, purchased from Jining Huakai Resin Co., Ltd.;

[0049] Solubilizer: N-methylpyrrolidone, analytical grade, purchased from Nanjing Chemical Reagent Co., Ltd.;

[0050] Acidity regulator: acetic acid, product number A801301, purchased from Shanghai MacLean Biochemical Technology; triethanolamine, analytical grade, purchased from Tianjin Komiou Chemical Reagent Co., Ltd.;

[0051] Chitosan: food grade, purchased from Shanghai Xibao Biotechnology Co., Ltd., with a deacetylation degree of 85% as determined by linear potentiometric titration and a weight-average molecular weight of approximately 260,000 as determined by 18-angle laser light scattering spectrometer;

[0052] Modified chitosan 1: Chitosan modified with citric acid and quaternary ammonium salt, homemade, the preparation method is as follows:

[0053] S1. Chitosan was dissolved in 2% acetic acid solution, stirred at 80°C until dissolved, 1% hydrogen peroxide solution was added dropwise, heated and stirred for 0.25 hours, cooled, 4 mol / L sodium hydroxide solution was added, the pH of the system was adjusted to 10 to precipitate chitosan, and the oligomeric chitosan sample was obtained after filtration, and dried at 40°C for later use; the weight average molecular weight was determined to be about 100,000 by 18-angle laser light scattering spectrometer;

[0054] S2. 10eq of citric acid and 1eq of sodium hypophosphite were dissolved in 100eq of deionized water, and 4eq of oligosaccharide chitosan was added in four batches. After complete dissolution, the mixture was stirred at 60-80°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, precipitated with 85% ethanol, washed three times, and filtered. After freeze-drying at -50°C, citric acid chitosan was obtained for later use.

[0055] S3. Dissolve 10eq of citric acid chitosan in deionized water, add 50eq of methanol and 1eq of anhydrous hydrogen chloride, stir and react at 60°C for 8 hours, and remove all solvents by vacuum distillation after the reaction to obtain citrate chitosan, which is freeze-dried for later use; the purpose of this step is to protect the carboxylic acid group on citric acid to prevent the subsequent reaction of quaternary ammonium salt with the carboxylic acid group of citric acid, and the excess solvent can be quickly removed by distillation;

[0056] S4. Mix 10eq of citrate chitosan and 15eq of 2,3-epoxypropyltrimethylammonium chloride in 100eq of deionized water, stir and react at 80℃ for 10h, add 1mol / L sodium hydroxide solution to adjust the pH value to 8-9 and continue to react for 4-6 hours, cool and adjust the pH value to 5.5 with 1mol / L hydrochloric acid; then precipitate and wash the solution with 85% ethanol, filter and dry to obtain modified chitosan. Under high temperature alkaline conditions, the citrate on chitosan is gradually hydrolyzed, and the carboxyl group is deprotected and converted back to carboxylic acid. Figure 1 The infrared spectra of chitosan, citric acid chitosan and its quaternary ammonium citrate chitosan are shown in Figure 1. 1 A new absorption peak appeared at 1600 cm-1, which was the absorption peak of C=O in the carboxyl group of citric acid, and chitosan -1 The amino bending vibration absorption peak at the position of chitosan disappears, which indicates that the amino group (-NH 2 ) was introduced into the quaternary ammonium citrate chitosan at 1486 cm -1 The methyl group (-CH 3 ) bending vibration absorption peak, and 1717cm -1 The absorption peak of C=O in the carboxyl group of citric acid did not shift, indicating that the quaternary ammonium salt was successfully grafted onto chitosan instead of citric acid.

[0057] Modified chitosan 2: Chitosan modified with citric acid and quaternary ammonium salt, homemade, the preparation method is different from that of modified chitosan 1 in that step S1 is different, as follows:

[0058] S1. Chitosan was dissolved in 2% acetic acid solution, stirred at 80°C until dissolved, 3% hydrogen peroxide solution was added dropwise, heated and stirred for 2 hours, cooled, 4 mol / L sodium hydroxide solution was added, the pH of the system was adjusted to 10 to precipitate chitosan, and the oligomeric chitosan sample was obtained by filtration, and dried at 40°C for use; the weight average molecular weight was determined to be about 21,000 by 18-angle laser light scattering spectrometer;

[0059] Modified chitosan 3: Chitosan modified with citric acid and quaternary ammonium salt, homemade, the preparation method is different from that of modified chitosan 1 in that step S1 is different, as follows:

[0060] S1. Chitosan was dissolved in 2% acetic acid solution, stirred at 80°C until dissolved, 2% hydrogen peroxide solution was added dropwise, heated and stirred for 1 hour, cooled, 4 mol / L sodium hydroxide solution was added, the pH of the system was adjusted to 10 to precipitate chitosan, and the oligomeric chitosan sample was obtained after filtration, and dried at 40°C for later use; the weight average molecular weight was determined to be about 42,000 by 18-angle laser light scattering spectrometer;

[0061] Modified chitosan 4: The preparation method is different from that of modified chitosan 1 in that step S1 is not performed.

[0062] Citric acid chitosan: Homemade, preparation method is as follows:

[0063] S1. Chitosan was dissolved in 2% acetic acid solution, stirred at 80°C until dissolved, 1% hydrogen peroxide solution was added dropwise, heated and stirred for 0.5 hours, cooled, 4 mol / L sodium hydroxide solution was added, the pH of the system was adjusted to 10 to precipitate chitosan, and the oligomolecular chitosan sample was obtained by filtration, and dried at 40°C for later use;

[0064] S2. 10eq of citric acid and 1eq of sodium hypophosphite were dissolved in 100eq of deionized water, and 4eq of oligosaccharide chitosan was added in four batches. After complete dissolution, the mixture was stirred at 60-80°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, precipitated with 85% ethanol, washed three times, and filtered. After freeze-drying at -50°C, citric acid chitosan was obtained.

[0065] Quaternary ammonium salt chitosan: The preparation method is as follows:

[0066] S1. Chitosan was dissolved in 2% acetic acid solution, stirred at 80°C until dissolved, 1% hydrogen peroxide solution was added dropwise, heated and stirred for 0.5 hours, cooled, 4 mol / L sodium hydroxide solution was added, the pH of the system was adjusted to 10 to precipitate chitosan, and the oligomolecular chitosan sample was obtained by filtration, and dried at 40°C for later use;

[0067] S2. Mix 10eq of oligomolecular chitosan and 15eq of 2,3-epoxypropyltrimethylammonium chloride in 100eq of deionized water, stir and react at 80°C for 10h, cool, precipitate and wash the solution with 85% ethanol, filter and dry to obtain quaternary ammonium salt chitosan.

[0068] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0069] Example 1

[0070] An organic plant dye nylon direct-injection digital printing process comprises the following steps:

[0071] Preparation of pretreatment pulp → fabric sizing → drying I → preparation of organic plant dye ink → digital printing → drying II → steaming → washing I → soap washing → washing II → drying III; the specific steps are as follows:

[0072] Preparing pretreated pulp: the pretreated pulp, by mass percentage, comprises the following components: 13% guar gum, 1% modified chitosan, 4% ammonium tartrate, 4% urea, a pH regulator content such that the pH value of the pretreated pulp is adjusted to 5, and the balance is water; the modified chitosan is modified chitosan 1;

[0073] The preparation method of the pretreated pulp is: firstly add urea into deionized water and stir thoroughly; then add ammonium tartrate and stir thoroughly; finally add 1 guar gum and 1 modified chitosan, stir for 2 hours and then stand for 24 hours.

[0074] Fabric sizing: completely immerse the nylon fabric in the slurry, take out the nylon fabric after 20 minutes, use a rolling car to remove excess slurry, adopt a two-immersion and two-rolling method, and the rolling rate is 90%. Dry and shape it immediately after rolling, bake at 105℃ for 3mmin, and put it into a sealed bag for storage after taking it out.

[0075] Formulating organic vegetable dye ink:

[0076] The red organic plant dye ink comprises the following components by mass percentage: 8% of monascus red pigment, 30% of moisturizing agent, 1% of solubilizing agent, 1% of surfactant, acetic acid and triethanolamine as pH regulators, the content of pH regulator is to adjust the pH value of the organic plant dye ink to 4.5, and the balance is deionized water;

[0077] The yellow organic plant dye ink comprises the following components by mass percentage: 8% of monascus yellow pigment, 30% of moisturizing agent, 1% of solubilizing agent, 1% of surfactant, acetic acid and triethanolamine as pH adjusters, the content of pH adjusters is such that the pH value of the organic plant dye ink is adjusted to 4.5, and the balance is deionized water;

[0078] The blue organic plant dye ink comprises the following components by mass percentage: 12% of gardenia blue pigment, 30% of moisturizing agent, 1% of solubilizing agent, 1% of surfactant, acetic acid and triethanolamine as pH regulators, the content of pH regulators is such that the pH value of the organic plant dye ink is adjusted to 4.5, and the balance is deionized water;

[0079] The black organic plant dye ink comprises the following components by mass percentage: 10% black pigment, 30% moisturizer, 1% solubilizer, 1% surfactant, acetic acid and triethanolamine as pH adjusters, the content of the pH adjuster is such that the pH value of the organic plant dye ink is adjusted to 4.5, and the balance is deionized water;

[0080] The preparation method of the organic plant dye ink is as follows: weigh the organic plant dye in proportion, add a solubilizer, a surfactant, a humectant, a pH regulator and deionized water, stir thoroughly until the dye is fully dissolved, ultrasonicate for 20 minutes to make the dye more evenly distributed in the system, and filter the prepared ink first with a 0.45 μm aqueous filter membrane and then with a 0.22 μm aqueous filter membrane.

[0081] Digital printing: Fix the nylon fabric and feed it into the guide belt digital printing machine for single-channel printing using Adobe Illustrator2021 software.

[0082] Steaming: The printed nylon fabric enters the steamer with the guide belt. The steaming temperature is 105℃, the state is saturated steam at normal pressure, and the time is 10 minutes:

[0083] Washing and drying: the water washing I is 40℃ warm water washing for 5min; the soap washing uses standard soap flakes 1.5g / L, the temperature is 95℃, and the washing is for 10min; the water washing II is 40℃ warm water washing for 5min, and then cold water washing for 5min; the water bath ratio of the soap washing, water washing I and water washing II is 30:1; the temperature of the drying I is 100℃; the temperature of the drying II is 85℃; the temperature of the drying III is 110℃;

[0084] Example 2

[0085] The process steps are different from those in Example 1, except that: the modified chitosan 1 in the pretreated pulp is replaced by modified chitosan 2;

[0086] Example 3

[0087] The process steps are different from those in Example 1, except that: the modified chitosan 1 in the pretreated pulp is replaced by modified chitosan 3;

[0088] Example 4

[0089] The process steps are different from those in Example 1, except that: the modified chitosan 1 in the pretreated pulp is replaced by modified chitosan 4;

[0090] Example 5

[0091] The process steps are different from those in Example 1, except that: the guar gum 1 in the pretreated pulp is replaced by guar gum 2;

[0092] Example 6

[0093] The process steps are different from those in Example 1, except that: the guar gum 1 in the pretreated pulp is replaced by guar gum 3;

[0094] Comparative Example 1

[0095] The process steps are different from those in Example 1, except that: the modified chitosan 1 in the pretreated pulp is replaced with citric acid chitosan;

[0096] Comparative Example 2

[0097] The process steps are different from those in Example 1 in that: the modified chitosan 1 in the pretreated pulp is replaced with quaternary ammonium salt chitosan;

[0098] Comparative Example 3

[0099] The process steps are different from those in Example 1 in that: the modified chitosan 1 in the pretreated pulp is replaced with chitosan;

[0100] Organic plant dye ink performance test

[0101] Ink has an important influence on the quality of printed images and the protection of printheads. The physical and chemical properties of ink, such as surface tension, viscosity and conductivity, are important indicators for ensuring image quality and printing fine patterns. The test methods and results of the surface tension, conductivity and viscosity of the organic plant dye ink are as follows:

[0102] (1) Surface tension: Use BZY-2 fully automatic surface tension meter and platinum sheet method to measure the surface tension of ink. First, take a proper amount of ink and put it in a surface dish. Clean the platinum sheet and burn it on an alcohol lamp. After cooling, start measuring. Test each sample three times and calculate the average value.

[0103] (2) Conductivity: Use a PE30-K conductivity meter. After calibrating the conductivity meter at room temperature, immerse all electrodes in the solution to be tested. Record the data after the value stabilizes. Perform the test three times and take the average value.

[0104] (3) Viscosity: Use NDJ-8S viscometer to test the viscosity. At room temperature, select rotor No. 0, pour an appropriate amount of the solution to be tested into the test tank, and adjust the speed to 60 mp. After the reading stabilizes, record the viscosity value of the solution. Test three times and take the average value.

[0105] Table 1 Organic plant dye ink performance test results

[0106] color Surface tension (mN / m) Conductivity (μS / cm) Viscosity (mPa·s) red 31.1 2429 3.41 yellow 30.6 1068 3.45 blue 37.5 789 3.77 black 32.7 1152 3.59

[0107] The surface tension and viscosity of organic plant dyes jointly affect the jetting morphology and jetting path of ink droplets. The surface tension of ink droplets determines the adhesion state of ink on fabric, which in turn affects the clarity of printed patterns. If the surface tension is too high, the area around the nozzle will not be easily wetted, so that ink droplets are difficult to form and difficult to break and gather around the nozzle, which will not only form blockages to cause intermittent interruptions in printing, but also affect the linear operation of ink droplets and the reproducibility of printing. If the surface tension is too low, the ink droplets will be unstable and form "satellite shapes". Preferably, the surface tension of the organic plant dye ink is 20 to 50 mN / m.

[0108] In the commonly used piezoelectric on-demand inkjet device, the ink droplets are deflected by the electric charge during printing, so the ink needs to have a certain conductivity. The conductivity of the ink reflects the salt content. Generally, the ink can be deflected by the charge when the conductivity is greater than 750μS / cm. However, if the conductivity of the ink is too high, the ink is easy to crystallize and clog the nozzle. Preferably, the conductivity of the organic plant dye ink is 750-3000μS / cm.

[0109] Viscosity is an important parameter in ink. If the viscosity is too high, the fluidity of the ink is reduced, and it is difficult to flow in the ink pipe. When spraying, it affects the spraying speed of the ink droplets, and the ink droplets are easy to break into a wire-like shape, making it difficult to form suitable ink droplets, thereby affecting the clarity of the printed image; if the viscosity is too low, it is not conducive to forming round ink droplets, and the ejected ink is easy to break, causing the ink to produce damping oscillation at the nozzle and unable to be sprayed. At the same time, it will also cause seepage on the fabric, reducing the printing effect. Preferably, the viscosity of the organic plant dye ink is 2 to 8 mPa·s.

[0110] Printing quality and fabric feel performance testing of inkjet printing

[0111] The nylon fabrics and printing quality of Examples 1 to 6 and Comparative Examples 1 to 3 were evaluated, wherein the printing contents of the inkjet printing were 15 cm×4 cm CMYK four-color blocks and 0.5 mm lines, and the color block K / S value, clarity and fixation rate of the printed fabric were tested.

[0112] (1) K / S value: measured using a DataColor 850 colorimeter, with the light source set to D65, the viewing angle set to 10°, the aperture selected to be a medium aperture (20 mm), and the fabric folded in half four times;

[0113] (2) Clarity: The change in line width was used to characterize the penetration of ink on the fabric. The obtained fabric was placed under an RH-2000 digital video optical microscope and magnified 40 times. The line width at different positions on the fabric was tested. The line width at 5 positions was tested and the average value was taken.

[0114] (3) Fixation rate: Based on the test method of the printing part of the national standard GB / T 2391-2014 "Determination of fixation rate of reactive dyes", the absorbance of the washing residue after the fabric is fully washed before and after steaming at the maximum absorbance wavelength is tested. The calculation formula is as follows: F = (1-A 1 / A 0 )×100%, where A 1 It indicates the absorbance of the fabric's washing residue at the maximum absorption wavelength after steam fixation; A 0 It indicates the absorbance of the washing residue of fabrics that have not been steamed and fixed at the maximum absorption wavelength.

[0115] (4) Color fastness: Color fastness to rubbing shall be measured in accordance with GB / T 3920-2008 “Textiles - Tests for color fastness - Color fastness to rubbing”; Color fastness to washing with soap shall be measured in accordance with GB / T 3921-2008 “Textiles - Tests for color fastness - Color fastness to washing with soap: Test 1”;

[0116] (5) Nylon softness test: Take the fabric after inkjet printing and form a 10-person evaluation team to score the softness of the nylon before printing. The softness level is divided into four levels: hard (1-3 points), relatively hard (4-5), relatively soft (6-7), and soft (8-10). The average of the scores of the 10 people is taken;

[0117] Table 2 Performance test results of printed fabrics of embodiments and comparative examples

[0118]

[0119]

[0120] From the data in Table 2, it can be seen that the printed nylon obtained by the treatment liquid in Examples 1 to 6 has the advantages of high K / S value, high color fixation rate, high color fastness, high clarity and good fabric feel. In Examples 1 to 3, chitosan is degraded to varying degrees, so that the molecular chain of chitosan becomes shorter, and it is not easy to form strong hydrogen bonds between molecules, which is conducive to the coating and dispersion of modified chitosan on the surface of nylon fabric fibers. From Examples 1, 5 and 6, it can be seen that the high-viscosity guar gum solution can better adhere to the surface of nylon fibers and form a uniform slurry coating during the pretreatment process, but when the viscosity is too high, a relatively dense film layer or covering layer may be formed on the surface of nylon fibers, preventing organic plant dye molecules from penetrating into the interior of the fibers, resulting in uneven printing effects, poor color fastness and other problems.

[0121] It can be seen from Comparative Examples 1, 2 and 3 that simple chitosan, citric acid chitosan and quaternary ammonium salt chitosan cannot achieve the effects of high K / S value, high color fixation rate, high color fastness, high clarity and good fabric feel achieved in Examples 1 to 6.

[0122] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A nylon direct-jet digital printing process with organic plant dyes, characterized in that: The following steps are involved: Preparation of pretreatment pulp → fabric sizing → drying I → preparation of organic plant dye ink → digital printing → drying II → steaming → washing I → soap washing → washing II → drying III; The pretreated pulp comprises the following components by mass percentage: 2-5% guar gum, 0.5-2% modified chitosan, 3-5% ammonium tartrate, 3-5% urea, 0-1% pH regulator, and the balance is water; the preparation method of the modified chitosan is as follows: S1. Chitosan was dissolved in acetic acid solution, stirred under heating conditions until dissolved, a hydrogen peroxide solution was added dropwise, heated and stirred for a period of time, and sodium hydroxide solution was added after cooling to adjust the pH of the system to alkaline, and the oligomolecular chitosan sample was obtained after filtration and dried for later use; S2. Dissolve citric acid and sodium hypophosphite in deionized water, add oligomolecular chitosan in batches, and stir and react at 60-80°C for 2-4 hours after complete dissolution. After the reaction, cool to room temperature, precipitate with ethanol, wash, filter, and freeze-dry to obtain citric acid chitosan for standby use; S3. Dissolve chitosan citric acid in deionized water, add methanol or ethanol and anhydrous hydrogen chloride, stir and react at 40 to 60 ° C for 6 to 12 hours, and remove all solvents by distillation under reduced pressure after the reaction to obtain chitosan citric acid ester, freeze-dried for standby use; S4. Mixing citrate chitosan and 2,3-epoxypropyltrimethylammonium chloride in deionized water, stirring and reacting at 70-90°C for 6-10 hours, adding sodium hydroxide solution to adjust the pH value to 8-9 and continue the reaction for 4-6 hours, and adjusting the pH value to 5-6 with hydrochloric acid after cooling; then precipitating and washing the solution with ethanol, filtering and drying to obtain modified chitosan; the pH value of the pretreated slurry is 5-6; The organic plant dye ink comprises the following components by mass percentage: 3-12% organic plant dye, 15-30% moisturizer, 0-1% solubilizer, 0.1-1% surfactant, 0-1% pH regulator, and the balance is deionized water; the pH value of the organic plant dye ink is 4-5.

2.

2. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The surface tension of the organic plant dye ink is 20-50 mN / m; the conductivity of the organic plant dye ink is 750-3000 μS / cm; and the viscosity of the organic plant dye ink is 2-8 mPa·s.

3. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The solubilizing agent is selected from one or more of polyethylene glycol and N-methylpyrrolidone; the surfactant is selected from one or more of dioctyl sodium succinate, sodium N-oleoyl polypeptide, benzalkonium chloride, alkyl trimethyl ammonium chloride, alkyl trimethyl ammonium bromide, N-alkyl betaine, and alkylphenol polyoxyethylene ether; the moisturizing agent is selected from one or more of ethanol, diethylene glycol, ethylene glycol, and glycerol; the pH regulator is one or more of acetic acid, hydrochloric acid, sulfuric acid, oxalic acid, triethanolamine, methylethanolamine, trimethylamine, and isopropanolamine.

4. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The colors of the organic plant dye include red, yellow, blue and black. The red organic plant dye is derived from one or more of sappan wood, peanut skin, madder, safflower, saffron, purple-leaved sorrel, apple blossom, cherry blossom, onion and red yeast rice; the yellow organic plant dye is derived from one or more of coptis chinensis, turmeric, rhubarb, rehmannia root, jujube, sappan wood, sophora japonica flower, gardenia, sedge grass, green grass, phellodendron, oak, pomegranate, astringent persimmon, turmeric, walnut, mulberry, onion, safflower yellow and red yeast rice; the blue organic plant dye is derived from one or more of gardenia blue, indigo, indigo, indigo, woad, indigo and indigo; the black organic plant dye is derived from one or more of terminalia chebula, gallnut, water chestnut, Chinese tallow tree, rhus chinensis, koreana and chemysalacia styracifolia.

5. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The preparation method of the pretreated pulp is: first add urea to deionized water and stir thoroughly; then add ammonium tartrate and stir thoroughly; finally add guar gum and modified chitosan, add a pH regulator to adjust the pH to 5-6, stir for 2 hours and then stand for 24 hours.

6. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The fabric sizing step is: completely immersing the nylon fabric in the slurry, taking out the nylon fabric after a period of time, using a rolling car to remove excess slurry, using a double immersion and double rolling method, drying and shaping immediately after rolling, and taking out and storing in a sealed bag.

7. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The preparation method of the organic plant dye ink is as follows: weigh a certain mass fraction of the organic plant dye, add a solubilizer, a surfactant, a humectant, a pH regulator and deionized water, stir thoroughly until the dye is fully dissolved, ultrasonicate for a period of time to make the dye more evenly distributed in the system, and filter the prepared ink first with a 0.45 μm aqueous filter membrane and then with a 0.22 μm aqueous filter membrane.

8. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The temperature of the drying I is 80-120°C; the temperature of the drying II is 65-105°C; the temperature of the drying III is 100-120°C; the steaming temperature is 100-105°C, the state is saturated steam at normal pressure, and the time is 10-30 minutes.

9. The organic plant dye nylon direct-injection digital printing process according to claim 1, characterized in that: The soap washing uses 1-2 g / L of standard soap flakes, a temperature of 90-100° C., and a washing time of 8-12 min. The water washing I is a warm water washing at 35-45° C. for 4-6 min. The water washing II is a warm water washing at 35-45° C. for 4-6 min, followed by a cold water washing for 4-6 min. The water bath ratios of the soap washing, water washing I, and water washing II are all 40:1-20:1.

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