Low-temperature one-bath dyeing process for polyester-cotton blended fabric

Abstract

The application discloses a low-temperature one-bath dyeing process for polyester-cotton blended fabric, which comprises the following steps: soaking the polyester-cotton blended fabric in an aqueous solution of alkaline ionic liquid for pretreatment to obtain a pretreated fabric with liquid; then mixing the pretreated fabric with liquid with reactive dyes and disperse dyes, and then performing supercritical CO2 fluid dyeing to obtain dyed fabric; the alkaline ionic liquid contains hydrophobic alkyl groups and has alkalinity; during the pretreatment, the alkaline anions form a hydrogen bond network with the hydroxyl groups of cellulose, thereby destroying the crystalline region of cellulose and increasing the dyeing rate; during the dyeing, the alkaline ionic liquid is distributed on the interface between water and CO2 fluid as a surfactant to form an inverse emulsion, thereby providing a microenvironment for the dyeing of cotton fibers by the reactive dyes; in addition, the alkaline anions of the alkaline ionic liquid can exchange with CO2 to generate carbonates, so that the polarity of the microenvironment is enhanced to be alkaline, and the reactivity of the reactive dyes and cotton fibers is improved, thereby improving the dyeing rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of printing and dyeing technology, in particular to a low-temperature one-bath dyeing process for polyester-cotton blended fabric. BACKGROUND

[0002] Polyester-cotton blended fabric has both the moisture absorption performance of cotton fiber and the good wear resistance, ironing-free performance and fast drying performance of polyester fiber, and plays an important role in knitted garment fabrics, but the printing and dyeing of polyester-cotton blended fabric has always been a difficulty.

[0003] The traditional dyeing process uses water as a medium, which plays an important role in dispersing and dissolving dyes and auxiliaries, wetting and swelling fibers, etc., but water pollution is very serious. In order to reduce the water consumption and dyeing wastewater of dyeing process, people have carried out a lot of research and are committed to developing water-saving and water-free dyeing technology. Supercritical CO2 fluid technology uses reusable CO2 to perform dyeing process under supercritical conditions with CO2 fluid as a medium, which has lower comprehensive cost than conventional dyeing process in terms of energy consumption, and realizes water-free dyeing, energy saving and emission reduction. Therefore, supercritical CO2 fluid dyeing technology has the technical advantages of water-free, emission reduction and energy saving, and is a new industrial production technology with development prospect.

[0004] Dyeing polyester-cotton blended fabric with supercritical CO2 fluid technology is the future development direction, which not only achieves the purpose of water saving and emission reduction, but also reduces the dyeing temperature and overcomes the need for high temperature in traditional dyeing process to achieve the dyeing of disperse dyes on polyester. However, due to the hydrophobicity of supercritical CO2 fluid, the solubility of reactive dyes is poor, and the swelling of cotton fabric is also poor, which needs to be improved. In the prior art, polyester-cotton blended fabric is pre-soaked in dimethyl sulfoxide (DMSO) and then enters the supercritical dyeing machine with liquid for dyeing. DMSO can swell cotton fibers, and DMSO can increase the polarity of supercritical CO2 fluid and improve the solubility of reactive dyes, thereby improving the dyeing rate of reactive dyes on cotton fibers. However, since reactive dyes generally need to be bonded to cotton fibers under alkaline conditions, the color depth and color fastness of the obtained blended fabric need to be improved. The prior art also reports the development of reactive disperse dyes, that is, the introduction of similar reactive groups in reactive dyes into the parent of disperse dyes, thereby obtaining a reactive dye with special structure and excellent dyeing performance, which realizes the dyeing of cotton fibers in supercritical CO2 fluid medium. However, the development of disperse reactive dyes is high in cost, and the use of disperse reactive dyes alone still cannot solve the problem of swelling of cotton fibers in supercritical CO2 fluid.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The application provides a low-temperature one-bath dyeing process for polyester-cotton blended fabric, which can use reactive dyes and disperse dyes to perform supercritical CO2 dyeing on the polyester-cotton blended fabric.

[0007] The application is implemented in the following manner:

[0008] The application provides a low-temperature one-bath dyeing process for polyester-cotton blended fabric, which comprises the following steps:

[0009] (1) soaking the polyester-cotton blended fabric in a pretreatment liquid to obtain pretreated fabric with liquid;

[0010] The pretreatment liquid is an aqueous solution of basic ionic liquid; the basic ionic liquid has the following molecular structure of formula I:

[0011] Formula I; in the formula, R1 is an alkyl group with 5-12 carbon atoms, and R2 is CH3 or C2H5;

[0012] (2) mixing the pretreated fabric with liquid and reactive dyes and disperse dyes, and then performing supercritical CO2 fluid dyeing to obtain dyed fabric.

[0013] In some embodiments, the basic ionic liquid is prepared in the following manner: after dissolving imidazole halide, adding a base to perform a heating reaction, purifying and drying to obtain the basic ionic liquid.

[0014] In some embodiments, the imidazole halide has the following molecular structure of formula II:

[0015] Formula II; in the formula, R1 is an alkyl group with 5-12 carbon atoms, and R2 is CH3 or C2H5; and X is Br, Cl or I.

[0016] In some embodiments, the base is sodium hydroxide or potassium hydroxide.

[0017] In some embodiments, the dissolving refers to dissolving the imidazole halide in at least one of methanol, ethanol or isopropanol.

[0018] In some embodiments, the heating reaction refers to heating to 40-80°C for 12-24 hours.

[0019] In some embodiments, the bath ratio of the polyester-cotton blended fabric to the pretreatment liquid in step (1) is 1:5-1:10.

[0020] In some embodiments, the amount of the basic ionic liquid used in step (1) is 10-20% o.w.f.

[0021] In some embodiments, the soaking in step (1) refers to standing for 0.5-1 hour.

[0022] In some embodiments, the belt liquid rate of the belt liquid pretreated fabric of step (1) is 50% to 70%.

[0023] In some embodiments, the reactive dye of step (2) is a triazine type reactive dye or a vinyl sulfone type reactive dye.

[0024] In some embodiments, the disperse dye of step (2) is an anthraquinone type disperse dye, an azo type disperse dye or a heterocyclic type disperse dye.

[0025] In some embodiments, the use amount of the reactive dye of step (2) is 1 to 2.5% o.w.f.

[0026] In some embodiments, the use amount of the disperse dye of step (2) is 1 to 2.5% o.w.f.

[0027] In some embodiments, the conditions of the supercritical CO2 fluid dyeing of step (2) include: temperature is 60 to 100℃, pressure is 18 to 24 MPa, time is 30 to 100 min, CO2 flow is 10 to 50 g / min.

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

[0029] The present application provides a low-temperature one-bath dyeing process for polyester-cotton blended fabric, which uses an aqueous solution of basic ionic liquid to pretreat the fabric, and then performs supercritical CO2 fluid dyeing with belt liquid. The obtained dyed fabric has good dye-uptake rate of reactive dye, high color depth and high color fastness. Specifically, the basic ionic liquid contains hydrophobic alkyl groups and has basicity. During pretreatment, the basic anion (OH - ) forms a hydrogen bond network with the hydroxyl groups of cellulose, thereby destroying the crystalline region of cellulose and increasing the dye-uptake rate. During dyeing, the basic ionic liquid acts as a surfactant and is distributed at the interface between water and CO2 fluid, forming a reverse emulsion, thereby providing a microenvironment for the dye-uptake of reactive dye on cotton fiber. In addition, the basic anion of the basic ionic liquid can exchange with CO2 to generate carbonate (2OH - + CO2 → CO3 2- + H2O), so that the polarity of the microenvironment is enhanced to be alkaline, thereby improving the reactivity of reactive dye and cotton fiber and increasing the dye-uptake rate. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. Other related drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 The ion chromatograms of the raw material imidazole halide (1-octyl-3-methyl imidazole bromide, 1-decyl-3-ethyl imidazole bromide, 1-dodecyl-3-methyl imidazole bromide, respectively) and the product basic ionic liquid used in Examples 1-3;

[0032] Figure 2 The XRD spectra of the cotton fabric obtained after the cotton fabric was pretreated using different pretreatment liquids. DETAILED DESCRIPTION

[0033] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. If specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturers are adopted. If the manufacturers of the reagents or instruments are not indicated, the conventional products that can be obtained by market purchase are adopted.

[0034] In the description of the embodiments of the present application, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0035] Reference to "embodiments" herein means that the specific features, structures or properties described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive or alternative to other embodiments.

[0036] In the embodiments of the present application, the term "or / and" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A or / and B, which can represent the three cases of A alone, A and B together, and B alone.

[0037] In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after it.

[0038] In the embodiments of the present application, the meaning of "a plurality of" is two or more (including two), and similarly, "a plurality of groups" means two or more groups (including two groups), and "a plurality of layers" means two or more layers (including two layers), unless otherwise explicitly specified and limited.

[0039] In the embodiments of the present application, the meaning of "at least one" is one or more than one.

[0040] The specific meanings of the above terms in the embodiments of the present application can be understood by those skilled in the art according to specific circumstances.

[0041] The features and performances of the present application are further described in detail below in combination with examples.

[0042] Example 1

[0043] A low-temperature one-bath dyeing process of polyester-cotton blended fabric, comprising the following steps:

[0044] (1) soaking the polyester-cotton blended fabric in an aqueous solution of 1-octyl-3-methylimidazolium hydroxide for 0.5 h and then taking it out to obtain a liquid-carrying pretreated fabric;

[0045] In the process, the polyester-cotton blended fabric is 70 / 30 polyester-cotton blended bleached fabric (13 tex x 13 tex, 614 / 10 cm x 283 / 10 cm);

[0046] The bath ratio of the polyester-cotton blended fabric to the pretreatment liquid is 1:8;

[0047] The amount of 1-octyl-3-methylimidazolium hydroxide used is 15% o.w.f.

[0048] The liquid-carrying rate of the liquid-carrying pretreated fabric is 60%;

[0049] The preparation method of 1-octyl-3-methylimidazolium hydroxide is as follows: 1-octyl-3-methylimidazole bromide is dissolved in isopropyl alcohol, an equimolar amount of sodium hydroxide is added, heated to 50℃ and refluxed for 12 h, then the insoluble impurities are removed by filtration, and then ether is added to precipitate the inorganic salt, the filtrate is obtained by filtration, and rotary evaporation is performed to dryness to obtain 1-octyl-3-methylimidazolium hydroxide.

[0050] (2) mixing the liquid-carrying pretreated fabric with C.I. Reactive Red 195 and C.I. Disperse Red 60, and then performing supercritical CO2 fluid dyeing, after the dyeing is completed, recovering CO2 by reducing the temperature and pressure to obtain a dyed fabric;

[0051] In the process, the amount of reactive dye used is 2% o.w.f.; the amount of disperse dye used is 2% o.w.f.

[0052] The conditions of the supercritical CO2 fluid dyeing include: temperature 80℃, pressure 20MPa, time 60min, CO2 flow rate 30g / min.

[0053] The reducing the temperature and pressure refers to reducing the pressure to 5MPa and reducing the temperature to 30℃, and recovering the dyes, ionic liquids, water and carbon dioxide through a separation kettle.

[0054] Example 2

[0055] A low-temperature one-bath dyeing process of polyester-cotton blended fabric, comprising the following steps:

[0056] (1) the polyester-cotton blended fabric is soaked in an aqueous solution of 1-decyl-3-ethyl imidazole hydroxide for 0.5 h and then taken out to obtain a liquid-carrying pretreated fabric;

[0057] The bath ratio of the polyester-cotton blended fabric to the pretreatment liquid is 1:5.

[0058] The amount of 1-decyl-3-ethyl imidazole hydroxide is 15% o.w.f.

[0059] The liquid-carrying rate of the liquid-carrying pretreated fabric is 50%.

[0060] The preparation method of 1-decyl-3-ethyl imidazole hydroxide is as follows: 1-decyl-3-ethyl imidazole bromide is dissolved in isopropyl alcohol, an equimolar amount of sodium hydroxide is added, heated to 50℃ and refluxed for 12 h, then the insoluble impurities are removed by filtration, and then ether is added to precipitate the inorganic salt, the filtrate is obtained by filtration, and rotary evaporation is performed to obtain 1-decyl-3-ethyl imidazole hydroxide.

[0061] (2) the liquid-carrying pretreated fabric and C.I. Reactive Yellow 145 and C.I. Disperse Yellow 114 are mixed, and then supercritical CO2 fluid dyeing is performed, after the dyeing is completed, the CO2 is recovered by reducing the temperature and pressure, and a dyed fabric is obtained;

[0062] The amount of the reactive dye is 1% o.w.f., and the amount of the disperse dye is 1% o.w.f.

[0063] The conditions of the supercritical CO2 fluid dyeing include: the temperature is 60℃, the pressure is 24 MPa, the time is 100 min, and the CO2 flow rate is 10 g / min.

[0064] The reducing the temperature and pressure refers to reducing the pressure to 5 MPa and reducing the temperature to 30℃, and recovering the dyes, ionic liquids, water and carbon dioxide through a separation kettle.

[0065] Example 3

[0066] A low-temperature one-bath dyeing process for a polyester-cotton blended fabric, comprising the following steps:

[0067] (1) the polyester-cotton blended fabric is soaked in an aqueous solution of 1-dodecyl-3-methyl imidazole hydroxide for 0.5 h and then taken out to obtain a liquid-carrying pretreated fabric;

[0068] The bath ratio of the polyester-cotton blended fabric to the pretreatment liquid is 1:5.

[0069] The amount of 1-dodecyl-3-methyl imidazole hydroxide is 15% o.w.f.

[0070] The liquid-carrying rate of the liquid-carrying pretreated fabric is 50%.

[0071] The preparation method of 1-dodecyl-3-methylimidazolium hydroxide is as follows: 1-dodecyl-3-methylimidazolium bromide is dissolved in isopropyl alcohol, and an equimolar amount of potassium hydroxide is added and heated to 50°C to reflux for 12 hours. After removing the insoluble impurities by filtration, inorganic salts are precipitated and separated out by adding ether. The filtrate is obtained by filtration and rotary evaporation to dryness to obtain 1-dodecyl-3-methylimidazolium hydroxide.

[0072] (2) The pretreated fabric with liquid is mixed with C.I. Reactive Blue 19 and C.I. Disperse Blue 367, and then supercritical CO2 fluid dyeing is performed. After dyeing, CO2 is recovered at reduced pressure and temperature to obtain the dyed fabric.

[0073] The amount of the reactive dye is 2.5% o.w.f., and the amount of the disperse dye is 2.5% o.w.f.

[0074] The conditions of the supercritical CO2 fluid dyeing include a temperature of 100°C, a pressure of 18 MPa, a time of 30 min, and a CO2 flow rate of 50 g / min.

[0075] The reduced pressure and temperature refers to reducing the pressure to 5 MPa and the temperature to 30°C, and recovering the dyes, ionic liquids, water and carbon dioxide through a separation kettle.

[0076] Ion chromatography is performed on the raw material imidazole halide (1-octyl-3-methylimidazolium bromide, 1-decyl-3-ethylimidazolium bromide and 1-dodecyl-3-methylimidazolium bromide) and the product basic ionic liquid of Examples 1-3. The test conditions are as follows: 0.15±0.0020 g of the test substance is accurately weighed and dissolved in ultrapure water, and then diluted to 100 mL. 1 mL of the diluent is diluted to 50 mL, filtered through a 0.22 μm filter, and then subjected to chromatographic analysis. A Diamonsil C18 chromatographic column is used, the mobile phase is 0.15 mmol / L TBAH-0.099 mmol / L malic acid-20% (v / v) acetonitrile aqueous solution, and the flow rate is 1 mL / min. The results are shown in the accompanying Figure 1 The results show that the peak area of Br- is greatly reduced after ion exchange, indicating that the concentration of Br- is reduced, and the anion of the ionic liquid is successfully replaced by OH-.

[0077] Example 4

[0078] The difference from Example 1 is that the amount of 1-octyl-3-methylimidazolium hydroxide is 10% o.w.f.

[0079] Example 5

[0080] The difference from Example 1 is that the amount of 1-octyl-3-methylimidazolium hydroxide is 20% o.w.f.

[0081] Example 6

[0082] The difference from Example 1 is that 1-pentyl-3-methylimidazolium hydroxide is used instead of 1-octyl-3-methylimidazolium hydroxide.

[0083] 1-pentyl-3-methylimidazolium hydroxide is prepared as follows: 1-pentyl-3-methylimidazolium bromide is dissolved in ethanol, and an equimolar amount of potassium hydroxide is added and heated to 50℃ to reflux for 12h, then the insoluble impurities are removed by filtration, and then ethyl ether is added to precipitate the inorganic salt, the filtrate is obtained by filtration and rotary evaporation to dryness to obtain 1-pentyl-3-methylimidazolium hydroxide.

[0084] Example 7

[0085] The difference from Example 1 is that 1-dodecyl-3-methylimidazolium hydroxide is used instead of 1-octyl-3-methylimidazolium hydroxide.

[0086] Comparative Example 1

[0087] A low-temperature one-bath dyeing process for polyester-cotton blended fabric, comprising the following steps:

[0088] The polyester-cotton blended fabric is mixed with C.I. Reactive Red 195 and C.I. Disperse Red 60, and then supercritical CO2 fluid dyeing is carried out, after dyeing, the CO2 is recovered by reducing the temperature and pressure to obtain the dyed fabric;

[0089] The amount of reactive dye is 2% o.w.f.; the amount of disperse dye is 2% o.w.f.

[0090] The conditions of supercritical CO2 fluid dyeing include: temperature is 80℃, pressure is 20MPa, time is 60min, CO2 flow rate is 30g / min.

[0091] The temperature is reduced to 30℃ and the pressure is reduced to 5MPa, and the dye, ionic liquid, water and carbon dioxide are recovered by a separation kettle.

[0092] Comparative Example 2

[0093] A low-temperature one-bath dyeing process for polyester-cotton blended fabric, comprising the following steps:

[0094] (1) The polyester-cotton blended fabric is soaked in dimethyl sulfoxide (DMSO) for 0.5h and then taken out to obtain a pretreated fabric with liquid;

[0095] The bath ratio of polyester-cotton blended fabric to DMSO is 1:5;

[0096] The liquor pick-up of the pretreated fabric with liquor was 60%.

[0097] The same as Example 1.

[0098] Comparative Example 3

[0099] The difference from Example 1 is that 1-octyl-3-methylimidazolium bromide is used instead of 1-octyl-3-methylimidazolium hydroxide as the ionic liquid.

[0100] The following is the study of the dyeing performance of ionic liquid on cotton fabric, the process is as follows:

[0101] The cotton fabric was immersed in 2wt% 1-octyl-3-methylimidazolium hydroxide aqueous solution, 2wt% 1-octyl-3-methylimidazolium bromide aqueous solution, DMSO respectively, and then placed for 0.5h. The fabric was sent to the supercritical CO2 dyeing machine with 60% liquor pick-up, without adding dye, and then washed with supercritical CO2 fluid for two times to obtain the fabric. The conditions of supercritical CO2 fluid include: temperature is 80℃, pressure is 20MPa, time is 20min, CO2 flow is 30g / min. The fabric was tested by X-ray diffraction (XRD) to study the crystal structure change of the treated fabric. The XRD test conditions are as follows: CuKα is used, the scanning range is 5-60°, and the scanning speed is 2° / min. The results are shown in the following figure: Figure 2 MDI Jade is used to perform background deduction, smoothing processing, characteristic peak fitting, and area calculation on the XRD spectrum, and then the crystallinity CI(%) is calculated by the following formula: I c is the integral area of all crystalline peaks, and I a is the integral area of amorphous region.

[0102] Cotton fabric was soaked in 2wt% aqueous solution of 1-octyl-3-methylimidazolium hydroxide, 2wt% aqueous solution of 1-octyl-3-methylimidazolium bromide, DMSO respectively, and then was put into supercritical CO2 dyeing machine with 60% belt liquid rate after standing for 0.5h, and 2% o.w.f. C.I. Reactive Red 195 was added, and the cotton fabric was dyed with supercritical CO2 fluid, and the fabric was separated, and then was pumped into supercritical CO2 fluid again for rinsing, and the dyed fabric was separated; the conditions of supercritical CO2 fluid included: temperature was 80°C, pressure was 20MPa, time was 30min, CO2 flow rate was 30g / min. The apparent color depth (K / S value) and level dyeing property of three samples were studied, and the test method of apparent color depth (K / S value) and level dyeing property were as follows: Datacolor 650 color matching instrument was adopted, D65 light source and 10° visual angle were selected, K / S value at the maximum absorption wavelength of the fabric was determined, each sample was measured at 10 different positions, and the average value was taken as the apparent color depth of the sample, and sample standard deviation of K / S value measured at different positions was calculated to measure the level dyeing property of the sample. The results were listed in Table 1.

[0103] Table 1

[0104]

[0105] From Table 1, it can be seen that soaking pretreatment is beneficial to reduce the crystallinity of cotton fiber and improve the dye-uptake of reactive dye on cotton fabric, and the K / S value of cotton fabric pretreated with 1-octyl-3-methylimidazolium hydroxide is the largest, followed by DMSO, and 1-octyl-3-methylimidazolium bromide is the worst; but the crystallinity of cotton fabric treated with DMSO is the lowest, followed by 1-octyl-3-methylimidazolium hydroxide, and 1-octyl-3-methylimidazolium bromide is the highest. On the one hand, it is shown that adding ionic liquid or polar solvent DMSO is beneficial to swelling of cotton fiber and opening of hydrogen bond inside cotton fiber, thereby being beneficial to diffusion and bonding of reactive dye; on the other hand, it is shown that 1-octyl-3-methylimidazolium hydroxide avoids excessive reduction of crystallinity of cotton fabric to achieve high dye-uptake, thereby avoiding poor wearing performance of cotton fiber, and improving level dyeing property. The reason is that: DMSO has small molecular weight and strong polarity, and has dissolving effect on cotton fiber, so the reduction of crystallinity of cotton fabric is large, thereby leading to poor level dyeing property; and 1-octyl-3-methylimidazolium hydroxide can be distributed at the interface of water and supercritical CO2 fluid to form reverse emulsion as the reaction microenvironment of reactive dye and cotton fiber due to its amphiphilic property, and its counterion OH- exchanges with CO2 fluid to generate carbonate (2OH - +CO2→CO3 2-+H2O), so that the microenvironment polarity is enhanced to be alkaline, the reactivity of the reactive dye with the cotton fiber is improved, and thus the dye uptake is improved. Neither DMSO nor 1-octyl-3-methyl imidazole bromide has such an effect.

[0106] The dyed fabrics obtained in Examples 1-7 and Comparative Examples 1-3 were subjected to apparent depth of color (K / S value) and color fastness tests, wherein the K / S value test method was consistent with the foregoing; the soaping fastness of the dyed fabrics was tested according to GB / T 3921-2008 "Textile color fastness test soaping fastness"; the rubbing fastness of the dyed fabrics was tested according to GB / T 3920-2008 "Textile color fastness test rubbing fastness", and the results are shown in Table 2.

[0107] To test whether the reactive dye reacts with the cotton fiber to fix the color and whether the disperse dye diffuses into the inside of the polyester, a stripping test was performed on the dyed fabric. A stripping solution was prepared by mixing 30 mL N-methyl pyrrolidone, 60 mL sodium hydroxide aqueous solution (38%), 3 g sodium hydrosulfite, and 64 mL deionized water. The mixed solution was heated to boiling, and the dyed fabric was then put into the stripping solution, so that the sample was immersed in the stripping solution. The stripping was performed for 20 min under the condition of a bath ratio of 1:14. The sample was washed with a small amount of distilled water and was dried at 60°C to obtain a stripped sample. The K / S value of the stripped fabric was determined, and the color fixation efficiency was calculated as (K / S) 后 / (K / S) 前 × 100%, (K / S) 前 , (K / S) 后 before and after stripping, respectively. The test method was consistent with the foregoing. The results are shown in Table 2.

[0108] Table 2

[0109]

[0110] From the data in Table 2, it can be seen that Comparative Examples 1-3 and Example 1 all use red dyes, and the apparent depth of color and color fastness and color fixation efficiency of the comparative examples are lower than those of Example 1. Since Comparative Example 1 is not pretreated, and the solubility of the reactive dye in supercritical CO2 fluid is poor, the dyeing is almost achieved by the disperse dye, and the disperse dye has poor wettability on the cotton fiber and cannot be bonded to the cotton fiber, so the dye uptake, color fastness, and color fixation efficiency are low. The K / S values of Comparative Examples 2 and 3 are lower than that of Example 1, which is consistent with the results in Table 1. In addition, since Comparative Examples 2 and 3 cannot provide alkaline conditions for the microenvironment, the reactive dye is difficult to bond to the surface of the cotton fiber, so the color fastness and color fixation efficiency are low.

[0111] The different basic ionic liquid adding amount is used in the embodiment 1, 4 and 5, with the increase of the ionic liquid amount, the K / S value of the dyed fabric is increased, but the further increase of the amount is not obvious to the increase of the K / S value.

[0112] The basic ionic liquid with different alkyl length is used in the embodiment 1, 6 and 7, with the increase of the carbon atom number in the alkyl, the K / S value of the dyed fabric is increased first and then decreased, the reason is that with the increase of the alkyl chain, the amphiphilic property of the ionic liquid is enhanced, the stable dispersion capacity to the water liquid is stronger, and it is more beneficial to the increase of the affinity of the two phases (water phase and supercritical CO2 fluid phase), thereby the dyeing rate is increased; but when the alkyl chain is too long, the hydrophobic property of the ionic liquid is too strong, the water solubility is decreased, the plasticizing effect on the cotton fabric during the pretreatment is decreased, however, it is not beneficial to the dyeing.

[0113] The above only for the preferred embodiment of the present application, and is not used to limit the present application, for the person skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A low-temperature co-bath dyeing process for polyester-cotton blended fabrics, characterized in that, Includes the following steps: (1) Immerse the polyester-cotton blended fabric in the pretreatment solution to obtain a pretreated fabric with liquid. The pretreatment solution refers to an aqueous solution of an alkaline ionic liquid; the alkaline ionic liquid has the following molecular structure: Formula I: In the formula, R1 is an alkyl group with 5 to 12 carbon atoms, and R2 is CH3 or C2H5; (2) The pretreated fabric with liquid is mixed with reactive dyes and disperse dyes, and then dyed with supercritical CO2 fluid to obtain dyed fabric.

2. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, The alkaline ionic liquid is prepared as follows: after dissolving the imidazole halide, an alkali is added and heated to react, and the mixture is purified and dried to obtain the alkaline ionic liquid.

3. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 2, characterized in that, The imidazole halide has the following molecular structure of Formula II: In the formula, R1 is an alkyl group with 5 to 12 carbon atoms, R2 is CH3 or C2H5, and X is Br, Cl or I.

4. A low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 2 or 3, characterized in that, The alkali is sodium hydroxide or potassium hydroxide; And / or, the dissolution refers to dissolving the imidazole halide in at least one of methanol, ethanol or isopropanol.

5. A low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 2 or 3, characterized in that, The heating reaction refers to heating to 40–80°C and reacting for 12–24 hours.

6. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, In step (1), the ratio of the polyester-cotton blended fabric to the pretreatment solution is 1:5 to 1:10; And / or, the amount of the alkaline ionic liquid used is 10-20% owf.

7. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, The soaking mentioned in step (1) refers to letting it stand for 0.5 to 1 hour; And / or, the liquid retention rate of the pretreated fabric is 50% to 70%.

8. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, The reactive dye in step (2) is a triazine reactive dye or a vinyl sulfone reactive dye; And / or, the disperse dye is anthraquinone disperse dye, azo disperse dye, or heterocyclic disperse dye.

9. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, The amount of reactive dye used in step (2) is 1-2.5% owf; And / or, the amount of the disperse dye used is 1 to 2.5% owf.

10. The low-temperature co-bath dyeing process for polyester-cotton blended fabrics according to claim 1, characterized in that, The conditions for supercritical CO2 fluid staining include: temperature of 60–100℃, pressure of 18–24 MPa, time of 30–100 min, and CO2 flow rate of 10–50 g / min.

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