An active dye printing process based on a mixed alkali application method

Abstract

The present application provides an active dye printing process based on a mixed alkali application method, belonging to the technical field of active dye printing. It includes pre-padding with alkali → drying → printing. The alkali solution used for pre-padding with alkali is any one or a compound thereof selected from sodium carbonate, sodium bicarbonate, sodium silicate, and sodium phosphate, preferably sodium phosphate, with a concentration of 8 - 15 g / L (pH value of 11.5 - 12.5) and a liquor ratio of 65 - 75%; in the printing process, the printing paste includes an active dye and an alkali agent. The concentration of the active dye x% ≥ 2.5%, and the addition amount T of the alkali agent and the concentration x% of the active dye satisfy the condition, and sodium bicarbonate is applied in a stepwise increasing manner according to the dye concentration. The above solution is used for active dye printing, which can better meet the differentiated requirements of alkali agents for printing different shades of printing paste, overcome the technical problem that the fabric alkalinity in the pre-padding with alkali process is single, resulting in uneven fixation rates for printing different concentrations of printing paste, and has a low urea dosage, effectively reducing the pollution rate of wastewater.

Description

Technical Field

[0001] The present application relates to an active dye printing process based on a mixed alkali application method, belonging to the technical field of active dye printing. Background Art

[0002] Reactive dyes have a complete chromatogram, bright color, and high wet fastness. They are the main dyes for printing cellulose fiber fabrics and are widely used in the printing of cotton, linen, and regenerated cellulose fiber fabrics. Due to the influence of the competitive reaction between fixation and hydrolysis, there are some problems in the direct printing of reactive dyes. For example, the fixation rate and build-up rate of reactive dyes are not high, generally ranging from 65% to 72%. This not only causes serious staining after washing, heavy washing burden, and large sewage discharge, but also requires a high amount of urea, which is likely to cause ammonia nitrogen exceeding the standard.

[0003] Reactive dyes generally need to react in an alkaline medium to achieve fixation. According to the different ways of adding alkali, the printing process can be divided into two forms: the one-shot method and the two-step method. The one-shot method is characterized by making the printing color paste by mixing reactive dyes, alkali agents, and other auxiliaries together. Due to the presence of alkali agents in the color paste, the color paste has poor stability and is easily interfered by environmental factors. In this process, generally, monochlorotriazine type reactive dyes with relatively low activity are selected to improve the stability of the color paste and avoid premature hydrolysis of the dyes. At the same time, a large amount of urea needs to be added to promote the fixation reaction. In the two-step method, no alkali agent is mixed into the printing color paste, but the dye fixation needs to be ensured by the method of padding alkali and short steaming after printing. This process has high color paste stability and is less affected by the environment. More reactive reactive dyes can be selected, but the process flow is long. The application method of the alkali agent and the fixation process conditions will have a great impact on the dye uptake and printing effect, and special alkali application devices and fixation equipment are required to be matched with it, resulting in its narrow applicability and less adoption in general factories. Summary of the Invention

[0004] In view of this, the present application provides an active dye printing process based on a mixed alkali application method, which not only overcomes the problems of single fabric alkalinity or unstable fixation rate of color pastes with different concentrations in the pre-padding alkali process, improves the universality of the two-step method, but also can realize the mixed application of alkali agents, achieve the gradient micro-application of color pastes, and meet the different differential requirements of alkali agents for printing color pastes with different shades.

[0005] Specifically, the present application is realized through the following solutions:

[0006] An active dye printing process based on a mixed alkali application method includes pre-padding alkali → drying → printing,

[0007] In the pre-padding alkali process, the alkali liquor used is any one or a compound thereof selected from sodium carbonate, sodium bicarbonate, sodium silicate, and sodium phosphate. The concentration of the alkali liquor is 8 - 15 g / L (pH is 11.5 - 12.5), and the liquor pickup rate is 65 - 75%;

[0008] In the printing process described above, the printing paste contains reactive dyes and an alkali agent. The concentration of the reactive dyes, x%, is ≥ 2.5%, the alkali agent is sodium bicarbonate, and the addition amount of the alkali agent, T, and the concentration of the reactive dyes, x%, satisfy the following conditions:

[0009] When 2.5% ≤ x% < 3.0%, T = 0.1;

[0010] When 3.0% ≤ x% < 3.5%, T = 0.2;

[0011] When 3.5% ≤ x% < 4.0%, T = 0.3;

[0012] When 4.0% ≤ x% < 4.5%, T = 0.4;

[0013] When 4.5% ≤ x% ≤ 5.0%, T = 0.5.

[0014] In the above scheme, while the reactive dyes undergo a fixation reaction with cellulose fibers, they also undergo a hydrolysis reaction with water. The fixation reaction and the hydrolysis reaction are a pair of competing reactions, as shown in Equation (1). During actual printing processing, it is necessary to precisely control the process to minimize the degree of hydrolysis reaction in order to achieve high fixation rate printing.

[0015]

[0016] In Equation (1), Dye: chromophore, R: alkyl or amide group, X: halogen atom, Cell-O - : cellulose fiber oxygen anion.

[0017] The fixation efficiency (E d ) of reactive dyes is determined by the ratio of the fixation rate (V f ) of the reaction between reactive dyes and cellulose fibers to the hydrolysis rate (V h ), as shown in Equation (2). The larger the ratio, the more dominant the fixation reaction is and the higher the fixation rate; conversely, the greater the degree of hydrolysis and the lower the fixation rate.

[0018]

[0019] In Equation (2), K f , K h respectively represent the fixation reaction rate constant and the hydrolysis reaction rate constant, [D] f , [D] s respectively represent the concentration of the dye in the fiber and the concentration in the aqueous solution, [Cell-O - represents the concentration of cellulose oxygen anions, and [OH - represents the concentration of hydroxide ions in the aqueous solution.

[0020] The color paste is printed on the fabric, and after drying, a layer of paste film is formed on the fabric surface. The dye molecules in the paste film absorb moisture and dissolve during subsequent steam heating, adsorb on the fiber surface, diffuse into the fiber interior, and react with cellulose oxyanions (Cell-O - ) to be fixed on the fiber. Therefore, to improve the fixation efficiency E d of reactive dye printing, it is necessary to increase the alkali concentration on cellulose fibers as much as possible to promote the dissociation of cellulose fiber hydroxyl groups (Cell-OH) into cellulose fiber oxyanions (Cell-O - ), as shown in Equation (3). At the same time, reduce the concentration of alkali [OH - in the color paste to prevent premature hydrolysis of the dye in the color paste.

[0021]

[0022] Based on the above principles and ideas, the present invention innovatively developed a mixed alkali application method of "pre-rolling the fabric with an alkali solution + gradient micro-alkali application in the color paste" during the reactive dye printing process. On the one hand, the pre-rolling of alkali effectively increases the alkalinity on cellulose fibers, while the micro-alkali application in the color paste (0 - 0.5% sodium bicarbonate) effectively reduces the dosage of alkali agents in the color paste (the sodium bicarbonate concentration in the color paste of the conventional full-formula printing method is generally 1 - 3%), thereby increasing the color paste stability and reducing the hydrolysis degree of the dye in the color paste; on the other hand, the combination of pre-rolling with an alkali agent having a certain buffering capacity and gradient micro-alkali application in the color paste realizes precise control of alkalinity and better meets the differential requirements of various light and dark color pastes for alkali agents.

[0023] Furthermore, as a preference:

[0024] The pH value of the alkali solution in the alkali rolling process is maintained at 11.5 - 12.5.

[0025] The drying temperature is 70 - 80 °C.

[0026] In the printing process, the reactive dye can be any one of P type (monochloro-s-triazine type), KE type (bis-monochloro-s-triazine type), KN type (bis-vinyl sulfone type), FL type (monofluoro-s-triazine and vinyl sulfone type), and M type (monochloro-s-triazine and vinyl sulfone type). More preferably, the reactive dye is any one of FL type, M type, and KN type.

[0027] In the printing process, it also includes a thickener, and the thickener is any one of sodium alginate or synthetic thickener or a compound of both. Sodium alginate needs to be pre-prepared into a stock paste and added in the form of the stock paste during color paste preparation. The addition amount of sodium alginate stock paste in the color paste is 40 - 60%, and the addition amount of synthetic thickener in the color paste is 3 - 8%. More preferably:

[0028] The preparation method of the sodium alginate stock paste is as follows: slowly add the sodium alginate paste to the continuously stirred warm water until it becomes a uniform paste. The dosage of sodium alginate is 3-12% (according to the product specifications, sodium alginate can be in three forms: high-viscosity sodium alginate, medium-viscosity sodium alginate, and low-viscosity sodium alginate. The dosage of high-viscosity sodium alginate is 3% - 4%, the dosage of medium-viscosity sodium alginate is 5% - 6%, and the dosage of low-viscosity sodium alginate is 8% - 12%), and the rest is made up to 100% with water.

[0029] The synthetic thickener is a polyacrylate synthetic thickener. It is convenient to prepare the paste with the synthetic thickener. When preparing the color paste, it can be directly weighed and used without the need to prepare it into a stock paste in advance.

[0030] After printing, it also includes steaming. The steaming temperature is 102 - 104°C, and the steaming duration is 6 - 10 min; more preferably, the printed fabric is dried and then sent to the steaming process. The drying temperature is 70 - 80°C; the fabric after steaming is washed and then taken out of the machine. The washing includes cold running water rinsing → washing at 60 - 85°C → soaping at 60 - 85°C (the soaping reagent contains 1 - 2 g / L detergent and 1 - 2 g / L soda ash) → washing at 60 - 85°C → cold water washing → taking out of the machine.

[0031] In this case, the mixed alkali application method of pre-rolling alkali and trace alkali application in the color paste for reactive dye printing is used to achieve precise control of the alkali agent throughout the printing process. It not only well avoids the hydrolysis problem caused by the use of the alkali agent during printing and ensures a stable fixation rate, but also can better meet the different differential requirements of alkali agents for printing with different shades of color paste. Description of the Drawings

[0032] Figure 1 Shows the influence of different sodium alkalis on the fixation rate of reactive dye printing in this application;

[0033] Figure 2 Shows the influence of sodium phosphate concentration on the fixation rate of printing with different shades of color paste in this application;

[0034] Figure 3 Shows the influence of sodium phosphate concentration on the fixation rate of printing with low-concentration color paste in this application,

[0035] a - Reactive Red FL - R, b - Reactive Yellow FL - PN, c - Reactive Blue FL - RN, d - Reactive Black KN - B;

[0036] Figure 4 Shows the influence of sodium bicarbonate concentration on the fixation rate of printing with medium - and high - concentration color paste,

[0037] a - 3% dye concentration, b - 5% dye concentration;

[0038] Figure 5Fixation rate of the printing process of mixing various dyes with alkali addition (synthetic thickener);

[0039] Figure 6 Fixation rate of the printing process of mixing various dyes with alkali addition (sodium alginate). Specific implementation mode

[0040] Example 1: Influence of pre-rolling alkali liquor on fixation rate

[0041] In this example, cotton fabric was used as the treatment object. First, pre-rolling alkali was carried out, and then printing was carried out. The specific process is as follows:

[0042] (1) Alkali rolling: After the cotton fabric was immersed in the alkali liquor, alkali rolling was carried out at room temperature, and the liquor pickup was 70%. The alkali liquors used were Na2CO3 (taking 2.5 g / L, 5 g / L, 7.5 g / L, 10 g / L as examples respectively), NaHCO3 (taking 2.5 g / L, 5 g / L, 7.5 g / L, 10 g / L as examples respectively), Na2SiO3 (taking 1 g / L, 2 g / L, 3 g / L, 5 g / L, 7 g / L, 9 g / L, 11 g / L, 13 g / L as examples respectively), and Na3PO4 (taking 1 g / L, 2 g / L, 3 g / L, 4.5 g / L, 6.5 g / L, 8.5 g / L, 11 g / L, 13 g / L as examples respectively).

[0043] (2) Drying: The fabric after alkali rolling was dried at 80 °C and then sent to the printing process.

[0044] (3) Printing: The mass percentage of each component in the printing paste was as follows: the concentration of reactive red FL-R was 1%, synthetic thickener 1680 was 4% (Shaoxing Bond Auxiliary Co., Ltd.), urea was 4%, and the rest was made up to 100% with water.

[0045] The preparation process of the printing paste was as follows: Weighing was carried out according to the paste formula respectively. An appropriate amount of water was added to synthetic thickener 1680 and stirred into the original paste. Then, an appropriate amount of water was used to dissolve the reactive dye, urea and alkali agent, and they were injected into the synthetic paste original paste, and then water was added to 100%, and continuously stirred until it became a uniform paste for standby.

[0046] (4) After printing, it was transferred to be dried at 80 °C, then steamed at 102 °C for 8 min, first rinsed with cold running water (room temperature) → washed with water at 60 °C → soaped at 60 °C (the soaping reagent contained 2 g / L detergent soap and 1.5 g / L soda ash) → washed with water at 80 °C → washed with cold water (room temperature) → taken out the cloth.

[0047] (5) The fixation rate of the taken-out cloth was measured to determine the relationship between the alkali agent and the fixation rate in the pre-rolling alkali process.

[0048] The influence of the selection of pre-rolling alkali liquor on the fixation rate is as Figure 1 shown.

[0049] From Figure 1 a, it can be seen that as the amount of alkali increases, the sodium carbonate reaches a high fixation rate (close to 95%) when it is 2.5 g / L, and then the fixation rate decreases linearly as the alkali agent increases.

[0050] The influence rules of other alkali agents are relatively similar: Combining Figure 1 a, 1b, as the amount of alkali agent increases, when the amount of alkali agent is relatively low (≤5 g / L), the fixation rate can reach a relatively high value (about 95%). When the amount of alkali agent continues to increase, the fixation rate begins to show a linear downward trend.

[0051] At the same time, it can also be found that the degree of decrease of different alkali agents is different; as shown in Figure 1 a, 1b: After the peak value of the fixation rate, sodium carbonate, sodium bicarbonate and sodium silicate show a relatively large linear decrease as the amount of alkali increases, while sodium phosphate decreases more gently.

[0052] The linear parts of the above alkali agents are linearly fitted respectively to obtain the functional relationship and the fitting degree R shown in Table 1 2 .

[0053] Table 1: Functional relationship between the amount of different alkali agents and the fixation rate of reactive dye printing

[0054] Serial number Alkali agent Fitting function <![CDATA[R 2 > 1 Sodium carbonate Y = -1.58X + 98.65 0.99387 2 Sodium bicarbonate Y = -1.64X + 101.60 0.99644 3 Sodium silicate Y = -1.62X + 98.27 0.97268 4 Sodium phosphate Y = -0.69X + 98.61 0.97073 .

[0055] It can be seen from Table 1 that as the amount of alkali agent increases, the degree of decrease in the fixation rate is different. Comparatively speaking, the decrease of sodium phosphate is relatively slow, and its slope is -0.69, while the slopes of the other several alkali agents are basically around -1.60. This shows that sodium phosphate has a certain buffering ability. The reason should be that sodium phosphate absorbs the protons released after the fixation or hydrolysis reaction of reactive dyes and becomes disodium hydrogen phosphate. Sodium phosphate and disodium hydrogen phosphate form a pair of buffer systems, which play a role in stabilizing the pH value to a certain extent, so that the fixation rate is relatively stable and there is no obvious decrease.

[0056] Example 2: Influence of the amount of pre-rolled alkali liquor on the fixation rate

[0057] In this example, cotton fabric is used as the treatment object. First, alkali padding is carried out, and then printing is carried out. The specific process is as follows:

[0058] (1) Alkali padding: After the cotton fabric is immersed in the alkali padding liquor, alkali padding is carried out, and the liquor pickup rate is 70%. The alkali liquor uses Na3PO4 (added in the form of sodium phosphate dodecahydrate).

[0059] (2) Drying: The fabric after alkali padding is dried at 80 °C and then sent to the printing process.

[0060] (3) Printing: Two types of printing color pastes are used, namely low-concentration color paste and high-concentration color paste, where:

[0061] 1) The mass percentage of each component in the low-concentration color paste is as follows: Reactive Red FL-R 1%, Synthetic Thickener 1680 6.85%, Urea 8%, and water is added to make up 100%.

[0062] 2) The mass percentage of each component in the high-concentration color paste is as follows: Reactive Black KN-B 5%, Synthetic Thickener 1680 6.85%, Urea 8%, and water is added to make up 100%.

[0063] The preparation processes of the above high- and low-concentration printing color pastes are the same: ① First, prepare the synthetic original paste: Take Synthetic Thickener 1680, add water and stir to form the synthetic original paste; ② Then dissolve the reactive dye and urea with water, inject the formulated amount of the synthetic original paste in step ①, continue to add water to make up 100%, and continuously stir until it becomes a uniform paste.

[0064] (4) After printing, transfer to drying at 80°C, then steam at 102°C for 8 min, first rinse with cold running water (room temperature) → wash at 60°C → wash with soap at 60°C (the soap washing reagent contains 2 g / L detergent soap and 1.5 g / L soda ash) → wash at 80°C → wash with cold water (room temperature) → take out the cloth.

[0065] (5) Measure the fixation rate of the taken-out cloth, and observe the changes in the fixation rates of the high-concentration color paste (i.e., 5% dye) and the low-concentration color paste (i.e., 1% dye) respectively with the change in the amount of sodium phosphate in the pre-padding alkali liquor, so as to observe the adaptability of the amount of sodium phosphate to printing with light and dark color pastes.

[0066] The influence results of the pre-padding alkali liquor amount on the fixation rate are shown in Figure 2 as follows.

[0067] From Figure 2 it can be seen that when the amount of sodium phosphate dodecahydrate is 25 g / L (the converted concentration of sodium phosphate is 10.75 g / L), the fixation rate of the light color paste is 91.3%, while the fixation rate of the dark color paste is only 23.5%; as the concentration of sodium phosphate increases, the fixation rate of the dark color paste also increases, while the fixation rate of the light color paste decreases; when the amount of sodium phosphate dodecahydrate is 45 g / L (the converted concentration of sodium phosphate is 19.4 g / L), the fixation rate of the dark color paste reaches 97.0%, while the fixation rate of the light color paste drops to 86.4%.

[0068] It can be seen that: When achieving high fixation rate printing (fixation rate higher than 90%) for light and dark color pastes, there are certain differences in the requirements for the sodium phosphate concentration of the pre-padding alkali liquor. The low-concentration color paste (also known as the light color paste) requires a low alkali agent concentration, while the high-concentration color paste (also known as the dark color paste) requires a high alkali agent concentration.

[0069] To simultaneously meet the requirements of high fixation rate printing for both concentrated and dilute color pastes, the present case proposes a mixed alkali application method. An appropriate amount of sodium phosphate is added to the alkali padding liquor to meet the low alkali demand of the low-concentration color paste, enabling the fixation rate to reach a relatively high level (close to 90%); for the high-concentration color paste, in addition to alkali padding, a trace amount of alkali is further added to the color paste to meet the higher alkali demand of the high-concentration color paste, making the fixation rate of the high-concentration color paste printing higher than 90%, thereby achieving precise control of the alkalinity and better meeting the differential alkalinity requirements of concentrated and dilute color pastes.

[0070] Combined with the above experimental results, Examples 3 and 4 are provided as representatives of the printing processes for low-concentration color paste and high-concentration color paste, respectively.

[0071] Example 3: Reactive dye printing process with mixed alkali application method for low-concentration color paste

[0072] In this example, a boundary of less than 3% is used for the low-concentration color paste, and experiments are conducted on the printing process plan for the low-concentration color paste.

[0073] Taking cotton fabric as the treatment object, alkali padding is carried out first, and then printing is carried out. The specific process is as follows:

[0074] (1) Alkali padding: After the cotton fabric is immersed in the alkali padding liquor, alkali padding is carried out with a liquor pick-up rate of 70%. The alkali liquor has a concentration of 25 g / L of sodium phosphate dodecahydrate (the converted concentration of sodium phosphate is 10.75 g / L) and a concentration of 30 g / L of sodium phosphate dodecahydrate (the converted concentration of sodium phosphate is 12.9 g / L), respectively.

[0075] (2) Drying: The fabric after alkali padding is dried at 80 °C and then sent to the printing process.

[0076] (3) Printing: The printing color paste adopts the formula shown in Table 2.

[0077] Table 2: Process prescriptions for each grade of low-concentration color paste

[0078] Dye concentration, % 0.5 1.0 2.0 3.0 Synthetic thickener 1680, % 3.25 4 5 5.5 Urea, % 3.5 4 5 6.0 Add water to, % 100 100 100 100 。

[0079] The preparation process of the above printing color paste is as follows: ① First, prepare the synthetic thickener paste: Take the synthetic thickener 1680 and stir it with water to form the synthetic thickener paste; ② Then, according to the formula in Table 2, weigh each material, dissolve the reactive red FL-R and urea with water, inject the formulated amount of the synthetic thickener paste in step ①, continue to add water to 100%, and continuously stir until it becomes a uniform paste.

[0080] (4) After printing, it is transferred to drying at 80 °C, then steamed at 102 °C for 8 min, and first rinsed with cold running water (room temperature) → washed at 60 °C → soaped at 60 °C (the soaping reagent contains 2 g / L of detergent soap and 1.5 g / L of soda ash) → washed at 80 °C → washed with cold water (room temperature) → taken out of the cloth.

[0081] (5) Measure the fixation rate of the output fabric, and measure the influence of the concentration of sodium phosphate in the alkali padding process on the fixation rate of the low-concentration color paste at different dye concentrations.

[0082] The reactive dye printing process of the mixed alkali application method for low-concentration color paste is as Figure 3 shown.

[0083] Comparing Figure 3 It can be seen from a~3d that when the dosage of sodium phosphate dodecahydrate is 25 g / L, for the low-concentration color paste (dye concentration is 0.5%), the fixation rates of the four reactive dyes (reactive red FL-R, reactive yellow FL-PN, reactive blue FL-RN, reactive black KN-B) are 88.4%, 86.8%, 89.9% and 89.8% respectively, which are basically close to 90%; for the medium-high concentration color paste (dye concentration reaches 3%), except that the fixation rate of the reactive red FL-R reaches 96.7%, the fixation rates of the other three reactive dyes are 46.4%, 89.6% and 76.2% respectively, indicating that the concentration of the pre-padded alkali agent is insufficient and cannot well meet the printing of medium-concentration color paste. When the dosage of sodium phosphate dodecahydrate is 30 g / L, for the low-concentration color paste (dye concentration is 0.5%), the fixation rates of the four dyes are 87.4%, 84.2%, 87.0% and 88.2% respectively, with a large gap from the 90% fixation rate; for the medium-high concentration color paste (dye concentration reaches 3%), there is still one dye (reactive yellow FL-PN) with a fixation rate of only 85.4%, which has a large gap from the expected target (fixation rate 90%).

[0084] In summary, when the dosage of sodium phosphate dodecahydrate in the alkali padding liquid is selected to be 25 g / L, the fixation rate of the low-concentration color paste is as close to or exceed 90% as possible. At this time, the highest dye concentration of the corresponding printing color paste is 2.5%. For color pastes with a concentration exceeding this value, it is necessary to add alkali liquor for printing by the mixed alkali application method.

[0085] Example 4: Reactive dye printing process of the mixed alkali application method for medium-high concentration color paste

[0086] Taking cotton fabric as the treatment object and reactive yellow FL-PN with a higher alkalinity requirement as the reactive dye, first perform alkali padding and then printing. The specific process is as follows:

[0087] (1) Alkali padding: After the cotton fabric is immersed in the alkali padding liquid, alkali padding is carried out, and the liquor pickup rate is 70%. The alkali liquor is sodium phosphate dodecahydrate with a concentration of 30 g / L (the converted concentration of sodium phosphate is 12.9 g / L).

[0088] (2) Drying: The fabric after alkali padding is dried at 80°C and then sent to the printing process.

[0089] (3) Printing: Printing was carried out using two grades of color pastes with medium concentration and high concentration respectively.

[0090] 1) The mass percentage of each component in the medium - concentration color paste was as follows: Reactive Yellow FL - PN 3%, Synthetic Thickener 1680 6.85%, Urea 8%, Sodium Bicarbonate concentrations were 0.025%, 0.050%, 0.075%, 0.100% respectively, and water was added to make up 100%.

[0091] 2) The mass percentage of each component in the high - concentration color paste was as follows: Reactive Yellow FL - PN 5%, Synthetic Thickener 1680 6.85%, Urea 8%, Sodium Bicarbonate concentrations were 0.3%, 0.35%, 0.40%, 0.45%, 0.5% respectively, and water was added to make up 100%.

[0092] The preparation processes of the above - mentioned high - and medium - concentration printing color pastes were the same: ① First, prepare the synthetic original paste: Take Synthetic Thickener 1680, add water and stir to form the synthetic original paste; ② Then, dissolve the reactive dye, urea and alkali agent (sodium bicarbonate in this example) with water, inject the formulated amount of the synthetic original paste in step ①, continue to add water to 100%, and continuously stir until it becomes a uniform paste.

[0093] (4) After printing, transfer it to be dried at 80°C, then steam at 102°C for 8 min, first rinse with cold running water (room temperature) → wash at 60°C → wash with soap at 60°C (the soap - washing reagent contains 2 g / L detergent soap and 1.5 g / L soda ash) → wash at 80°C → wash with cold water (room temperature) → take out the cloth.

[0094] (5) Measure the fixation rate of the taken - out cloth, and measure the influence of the concentration of sodium phosphate in the alkali - padding process on the fixation rate of the color paste at different dye concentrations.

[0095] The printing process of reactive dyes by the method of mixed alkali application with medium - high concentration color paste is as Figure 4 shown.

[0096] Figure 4 It can be seen that: when the dye concentration in the color paste is 3%, and the concentration of sodium bicarbonate in the color paste is 0.05%, the fixation rate has reached 96.2% (see Figure 4 a); when the dye concentration in the color paste rises to 5%, with the increase of the concentration of sodium bicarbonate applied in the color paste, the fixation rate gradually increases (see Figure 4 b). When the concentration of sodium bicarbonate is 0.5%, the fixation rate reaches 95.7%. Based on the above results, we verified that the proposed scheme of gradient - type micro - alkali application in the color paste in this case is feasible. According to the dye concentration in the color paste from low to high, the concentration of sodium bicarbonate in the color paste increases in a gradient manner, and the specific scheme is shown in Table 3.

[0097] Table 3: Gradient alkali application scheme for medium - high concentration color paste

[0098] Dye concentration, % 2.5～3.0 3.0～3.5 3.5～4.0 4.0～4.5 4.5～5.0 Sodium bicarbonate, % 0.1 0.2 0.3 0.4 0.5 。

[0099] Example 4-1

[0100] This example is the same as that of Example 4, except that: the thickener in the above printing process is replaced with sodium alginate original paste, and experiments are carried out under the same conditions.

[0101] Example 4-2

[0102] This example is the same as that of Example 4, except that: the reactive dyes are replaced with reactive dyes of three colors, red, blue and black (taking reactive red FL-R, reactive blue FL-RN and reactive black KN-B as examples), and two thickeners, synthetic thickener and sodium alginate, are respectively used to carry out experiments under the same conditions.

[0103] The experimental results of the thickeners in Example 4-1 and Example 4-2 are as Figure 5 and Figure 6 shown.

[0104] From Figure 5 it can be seen that when using synthetic thickener 1680 to prepare the color paste, the fixation rates of the color pastes of the reactive dyes of four colors (taking reactive red FL-R, reactive yellow FL-PN, reactive blue FL-RN and reactive black KN-B as examples) at each concentration level have all reached over 90%, the colors are full and bright, achieving high fixation rate printing.

[0105] Figure 6 It can be seen that when using sodium alginate original paste to prepare the color paste, although the fixation rates of the reactive dyes of four colors (taking reactive red FL-R, reactive yellow FL-PN, reactive blue FL-RN and reactive black KN-B as examples) are slightly lower than those of the corresponding printing fixation rates of the synthetic original paste, they also all reach over 90%.

[0106] The above results verify again that the reactive dye printing process of the mixed alkali application method in this case is indeed feasible.

[0107] At the same time, the applicant also carried out experiments on the dosage of urea. The results show that: when the urea dosage is controlled at 4-8%, normal printing can be achieved, which is much lower than that of the conventional all-material method printing (the general urea dosage is 10-15%). Using the method of this case can achieve high fixation rate printing and effectively reduce the sewage content rate of the wastewater. This printing process has broad application prospects.

Claims

1. An active dye printing process based on a mixed alkali application method, characterized in that, Including pre-rolling alkali → drying → printing → steaming, In the pre-rolling alkali process, the alkali liquor used is sodium phosphate with a concentration of 8 - 15 g / L, the pH value of the alkali liquor is maintained at 11.5 - 12.5, and the liquor pickup rate is 65 - 75%; In the printing process, the color paste includes reactive dyes, urea and sodium bicarbonate. The addition amount of urea is 4 - 8%. The concentration of the reactive dyes x% ≥ 2.5%, and the addition amount T of sodium bicarbonate and the concentration of the reactive dyes x% satisfy: 2.5% ≤ x% < 3.0%, T = 0.1%; 3.0% ≤ x% < 3.5%, T = 0.2%; 3.5% ≤ x% < 4.0%, T = 0.3%; 4.0% ≤ x% < 4.5%, T = 0.4%; 4.5% ≤ x% ≤ 5.0%, T = 0.5%, The reactive dyes are any one of FL type, M type and KN type, The temperature of the steaming is 102 - 104 °C and the duration is 6 - 10 min.

2. The reactive dye printing process based on the hybrid alkali application method according to claim 1, characterized in that: The color paste also includes a thickener. The thickener is any one of sodium alginate thickener or synthetic thickener or a compound of the two. The sodium alginate thickener is added in the form of a stock paste in the color paste, and the addition amount is 40 - 60%; the addition amount of the synthetic thickener in the color paste is 3 - 8%.

3. A reactive dye printing process based on a mixed alkali application method according to claim 2, characterized in that, The preparation method of the sodium alginate stock paste is: gradually and slowly add sodium alginate into the stirred water until it becomes a uniform paste. The amount of sodium alginate used is 3 - 12%, and the rest is filled with water to 100%.

4. The reactive dye printing process based on the hybrid alkali application method according to claim 2, characterized in that, The preparation method of the sodium alginate stock paste is: gradually and slowly add sodium alginate into the stirred water until it becomes a uniform paste. The sodium alginate includes high-viscosity sodium alginate, medium-viscosity sodium alginate and low-viscosity sodium alginate. The amount of high-viscosity sodium alginate used is 3 - 4%, the amount of medium-viscosity sodium alginate used is 5 - 6%, the amount of low-viscosity sodium alginate used is 8 - 12%, and the balance is water.

5. A reactive dye printing process based on a mixed alkali application method according to claim 2, characterized in that: The synthetic thickener is a polyacrylate synthetic thickener.

6. A reactive dye printing process based on a mixed alkali application method according to claim 1, characterized in that: Drying is included between printing and steaming, and the drying temperature is 70 - 80 °C.

7. A reactive dye printing process based on a mixed alkali application method according to claim 1, characterized in that: After steaming, washing is included. The washing includes cold running water rinsing → washing at 60 - 85 °C → soaping at 60 - 85 °C. The soaping reagent contains 1 - 2 g / L of detergent and 1 - 2 g / L of soda ash → washing at 60 - 85 °C → cold water washing → cloth discharging.

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