A dyeing method for deep-dyed ultra-fine leather with high color fastness

Abstract

The present invention relates to a dyeing method for a deep-dyed microfiber leather with high color fastness. The main components of the microfiber leather are solvent-based polyurethane and nylon microfiber. The dyeing comprises the following steps: (1) acid dye dyeing: the microfiber leather is placed in a dyeing solution of an acid dye, and the acid dye uptake rate is adjusted so that the L value of the microfiber leather after acid dye dyeing is less than 22; (2) reactive dye dyeing: the microfiber leather that has not been dried after acid dye dyeing in step (1) is placed in a dyeing solution of a reactive dye, and the reactive dye uptake rate is controlled to be 0.1 to 0.2 times of the acid dye uptake rate; (3) alkali washing: after dyeing, a soda solution with a concentration of 0.1 to 0.5 g / L is used, and according to the bath ratio during reactive dye dyeing, alkali washing is performed at 50 to 70° C. for 20 to 30 minutes to obtain a product. The present invention sequentially dyes with acid dyes and reactive dyes, and combines a specific alkali washing process, so that the color migration level of the product obtained can reach level 4 or above.

Description

Technical Field

[0001] The invention belongs to the technical field of ultra-fine leather dyeing, and relates to a dyeing method for ultra-fine leather with high color fastness and deep dyeing. Background Art

[0002] Due to the requirements of green, environmental protection, and low carbon, it is imperative to remove the leather. In this context, microfiber materials, as a perfect alternative material, not only have the advantages of good feel, appearance, comfort and high utilization efficiency, but also have two typical products: veneer leather and suede leather. At the same time, suede products are a major advantage that distinguishes it from other fabric materials. At present, the main microfiber materials on the market are nylon plus resin microfibers.

[0003] However, acid dyes are usually used for deep dyeing of microfiber leather products, and the poor color fastness (including color fastness to sweat, soaping and water stains) of dark suede products has always been a major problem. Therefore, a new dyeing method is needed to solve the color fastness problem on nylon suede.

[0004] Acid dyes are a type of dye that contains an acidic group in the molecule, usually present in the form of sodium sulfonate or sodium carboxylate on the dye molecule. It is well known that there are two ways to combine acid dyes with microfiber products: physical adsorption and chemical bonding. Among them, the acid dye group is mainly combined with nylon fiber by chemical bonds. The principle is that the sodium sulfonate or sodium carboxylate of the acid dye reacts with the amino group of nylon and then combines with ionic bonds. Acid dyes are mainly combined with polyurethane resins by physical adsorption, but when acid dyes are combined with polyurethane resins, the physical adsorption binding force is poor, so it is easy to cause precipitation and overflow.

[0005] Therefore, it is of great significance to study a dyeing method for deep-dyed ultra-fine leather with high color fastness to solve the problems existing in the prior art. Summary of the invention

[0006] The purpose of the invention is to solve the problems existing in the prior art and provide a dyeing method for dark-dyed microfiber leather with high color fastness.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A dyeing method for a deep-dyed microfiber leather with high color fastness, wherein the main components of the microfiber leather (the microfiber leather includes a microfiber base fabric and a finished leather further processed on the basis of the microfiber base fabric) are solvent-based polyurethane and nylon microfiber, comprising the following steps:

[0009] (1) Dyeing with acid dyes: Place the microfiber leather in a dye solution of an acid dye, and adjust the acid dye uptake (the percentage of the dye in the microfiber leather to the total mass of the dye in the initial dye bath after dyeing) so that the L value of the microfiber leather after acid dyeing is less than 22, such as 15, 17, 18, 19, 21; preferably, the L value is controlled to be 15-21. The numerical values ​​of the parameters listed in the present invention should be understood as being limited by the term "approximately" in all cases, such as the numerical value 21 includes 21.06.

[0010] (2) Dyeing with reactive dyes: the undried microfiber leather after dyeing with acid dyes in step (1) is placed in a dyeing solution of reactive dyes, and the dyeing rate of reactive dyes is controlled to be 0.1 to 0.2 times of that of acid dyes; if the dyeing rate of reactive dyes is low, the desorption of acid dyes is still serious, which is manifested as poor color migration; if the dyeing rate of reactive dyes is too high, a more stringent alkaline washing environment is required to achieve the target dyeing rate of reactive dyes, which will cause the dyed acid dyes to be destroyed by the alkaline solution;

[0011] (3) Alkali washing: After dyeing, use a soda ash (Na2CO3) solution with a concentration of 0.1-0.5 g / L, according to the bath ratio when dyeing with reactive dyes, and wash at 50-70°C for 20-30 minutes to obtain a dark-dyed microfiber leather with high color fastness. The soda ash concentration used for alkaline washing is relatively low, and the reaction degree of the reactive dye is controlled, because excessive reaction will result in poor coloring effect.

[0012] It is usually not possible to prepare a composite dye of reactive dye and acid dye, because the acid dye is a type of dye containing an acidic group in the molecule, which is usually present on the dye molecule in the form of sodium sulfonate or sodium carboxylate. Direct dyeing with composite dyes can easily lead to severe discoloration of acid dyes on polyurethane after alkali washing, large color changes, and poor color fastness due to unclean alkali washing. The above problem can be solved by dyeing in steps and adjusting the alkali washing conditions.

[0013] As the preferred technical solution:

[0014] In the dyeing method of a deep-dyed microfiber leather with high color fastness as described above, the mass ratio of solvent-based polyurethane to nylon microfiber in the microfiber leather is 3:7 to 4:6.

[0015] The dyeing method of the dark-dyed microfiber leather with high color fastness as described above has an L value of less than 22 and a color migration grade of 4 or above.

[0016] In the dyeing method of a high color fastness dark-dyed microfiber leather as described above, the concentration of the dye solution of the acid dye in step (1) is 0.25-1.0wt%, the bath ratio is 1:10-20 (1g microfiber leather corresponds to 10-20g dye solution), and the acid dye uptake rate is 98-99%.

[0017] As described above, in the dyeing method of a high color fastness dark-dyed microfiber leather, in step (1), the dyeing temperature is 85-100°C, the heating rate is 0.5-2°C / min, the dyeing time is 20-60min, and after dyeing, the temperature is lowered to 50-60°C and washed with water for 30min.

[0018] Generally, the higher the dye concentration in the dye solution, the smaller the bath ratio, and the higher the dyeing temperature, the greater the dye uptake rate and the smaller the L value; the lower the dye concentration, the larger the bath ratio, and the lower the dyeing temperature, the smaller the dye uptake rate and the larger the L value.

[0019] In the dyeing method of a high color fastness dark-dyed microfiber leather as described above, the concentration of the dye solution of the reactive dye in step (2) is 0.005-0.099wt%, and the bath ratio is 1:10-20.

[0020] In the dyeing method of a high color fastness dark-dyed microfiber leather as described above, in step (2), the dyeing temperature is 85-100° C., the heating rate is 0.5-2° C. / min, the dyeing time is 20-60 min, and the temperature is lowered to 50-60° C. after dyeing.

[0021] Principle of the invention:

[0022] Compared with acid dyes, reactive dyes are a type of dye that is difficult to be adsorbed by polyurethane resins and are generally difficult to use for dyeing microfiber leather. The inventor unexpectedly discovered that when reactive dyes are used as auxiliary dyes for acid dyes, after alkali washing, the physical desorption of acid dyes by polyurethane resins can be hindered, which is specifically manifested as a significant improvement in color fastness. It is speculated that this may be because after the acid dyes are adsorbed by polyurethane, reactive dyes are further introduced. During alkali washing, the products formed by the process of coloring with nylon during reaction change the desorption environment, so that the introduction of such reactive dyes affects the desorption ability of acid dyes.

[0023] The transformation of active groups in reactive dyes needs to be under alkaline conditions, so it is necessary to dye with acid dyes first and then with reactive dyes. It is necessary to explore a suitable alkali washing process, otherwise the acid dyes will be destroyed. When the conventional reactive dye alkali washing process (1g / L soda, 80°C water washing temperature, 40min alkali washing) is used, dyeing failure usually occurs. This is because the process treatment will cause serious damage to the structure of the acid dye, resulting in the inability to dye. The inventors adopted a specific alkali washing process to avoid the problem of acid dyes being significantly damaged and unable to dye, that is, 0.1-0.5g / L soda solution, alkali washing at 50-70°C for 20-30min. The alkali washing process used in the prior art is because the reactive dyes need to react with nylon under alkali washing conditions to improve the colorability. In the present invention, the dyeing rate of acid dyes on nylon is already very high, and the inventors mainly hope to use reactive dyes to help hinder the physical desorption of acid dyes by polyurethane resin. Therefore, it is only necessary to make the active dye react with nylon to a certain extent to change the desorption environment of the acid dye, which is essentially different from the prior art.

[0024] Beneficial effects:

[0025] The invention discloses a dyeing method for a high color fastness dark-dyed microfiber leather, which adopts a reactive dye as an auxiliary dye of an acid dye, first dyes with an acid dye, then dyes with a reactive dye, and combines with a specific alkali washing process, so that the color migration grade of the obtained high color fastness dark-dyed microfiber leather can reach above grade 4; while the prior art adopts a simple acid dye, and the color migration grade is only grade 2 to 3. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0027] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0028] (1) L value: The microfiber leather was measured using a KONICA MINOLTA spectrophotometer, model CM-25cG-SP. Colors with an L value below 50 are considered dark. The lower the L value, the darker the color.

[0029] (2) Color migration: Color migration is measured according to the method specified in ISO 15701:2015EN Leather and is divided into 1 to 5 levels. The lower the level, the easier it is for the dye to migrate out and stick to the surface of the contact object under certain temperature and humidity. The higher the level, the less likely the dye is to precipitate out of the material and contaminate the contact object.

[0030] Sources of some substances of the present invention:

[0031] Acid dye: Manufacturer: Qingdao Yuzhen, Brand: Bright Red PDC-3G.

[0032] Reactive dyes: Manufacturer: Shanghai Xingkang, Brand: Anmeilan\Scarlet NW.

[0033] Nylon microfiber leather 1: Manufacturer: Shanghai Huafeng Microfiber Technology Co., Ltd., brand: EDGW0-080A12 (0.8 mm thickness), mass ratio of solvent-based polyurethane and nylon microfiber is 3.5:7.5, used in Examples 1 to 3 and Comparative Examples 1 to 3.

[0034] Nylon microfiber leather 2: Manufacturer: Shanghai Huafeng Microfiber Technology Co., Ltd., brand: EDXW0-080A12 (0.85 mm thickness), mass ratio of solvent-based polyurethane and nylon microfiber 3.8:7.2, used in Example 4.

[0035] Nylon microfiber leather 3: Manufacturer: Shanghai Huafeng Microfiber Technology Co., Ltd., brand: EGGW0-080A12, the mass ratio of solvent-based polyurethane and nylon microfiber is 4.0:6.0, used in Example 5.

[0036] Example 1

[0037] A dyeing method for deep-dyed microfiber leather with high color fastness, the specific steps are as follows:

[0038] (1) Acid dye dyeing: The nylon microfiber leather 1 is placed in a dye solution with an acid dye concentration of 0.25 wt % at a bath ratio of 1:10, and the acid dye uptake rate is adjusted to 99% so that the L value of the microfiber leather after acid dye dyeing is 21.06;

[0039] The dyeing temperature was 85°C, the heating rate was 1°C / min, the dyeing time was 20min, and after the dyeing was completed, the temperature was lowered to 50°C and washed with water for 30min.

[0040] (2) reactive dye dyeing: placing the undried microfiber leather after acid dye dyeing in step (1) into a dyeing solution with a concentration of 0.005 wt % reactive dye in a 1:10 bath ratio, and controlling the reactive dye uptake to be 0.1 times the acid dye uptake;

[0041] The dyeing temperature was 85°C, the heating rate was 1°C / min, the dyeing time was 20min, and the temperature was lowered to 50°C after the dyeing was completed;

[0042] (3) Alkali washing: After dyeing, use a 0.1 g / L soda ash solution according to the bath ratio of reactive dyeing, and wash at 50°C for 30 minutes to obtain a dark-dyed microfiber leather with high color fastness.

[0043] The L value of the finally obtained high color fastness dark dyed microfiber leather is 21.22, and the color migration grade is 4.5.

[0044] Comparative Example 1

[0045] A method for dyeing dark-dyed microfiber leather is basically the same as that of Example 1, except that the operations of step (2) and step (3) are omitted, that is, only acid dyeing is performed.

[0046] The L value of the dark-dyed microfiber leather finally obtained is 21.09, and the color migration grade is 2.

[0047] By comparing Comparative Example 1 with Example 1, it can be found that the color migration level of Comparative Example 1 is low. This is because when a large amount of dye is added to darken the base fabric, when only conventional acid dyes are used for dyeing, a large amount of dye is dyed on the polyurethane. Although it is easy to color the polyurethane, it is also easy to decolorize, resulting in the problem of poor color migration.

[0048] Comparative Example 2

[0049] A method for dyeing dark-dyed microfiber leather is basically the same as that in Example 1, except that the dyeing rate of the reactive dye in step (2) is 0.05 times the dyeing rate of the acid dye.

[0050] The L value of the dark-dyed microfiber leather finally obtained is 21.13, and the color migration grade is 2.5.

[0051] Comparing Comparative Example 2 with Example 1, it can be found that the reactive dye uptake ratio in Comparative Example 2 is too low. This is because too low reactive dye uptake will lead to severe desorption of acid dyes, which is manifested as poor color migration.

[0052] Comparative Example 3

[0053] A method for dyeing dark-dyed microfiber leather is basically the same as Example 1, except that the reactive dye uptake in step (2) is 0.3 times the acid dye uptake, and the concentration of the soda ash solution used in alkali washing in step (3) is 1 g / L.

[0054] The L value of the dark-dyed microfiber leather finally obtained was 25.08, and the color migration grade was 4.5.

[0055] By comparing Comparative Example 3 with Example 1, it can be found that the L value of Comparative Example 3 becomes larger. This is because if the reactive dye uptake rate is too high, a more stringent alkaline washing environment is required to achieve the target reactive dye uptake rate, which will cause the acid dye to be destroyed by the alkaline solution, and the final color will be lighter, affecting the accuracy of the final color.

[0056] Example 2

[0057] A dyeing method for deep-dyed microfiber leather with high color fastness, the specific steps are as follows:

[0058] (1) Acid dye dyeing: The nylon microfiber leather 1 is placed in a dye solution with an acid dye concentration of 0.40 wt % at a bath ratio of 1:12, and the acid dye uptake rate is adjusted to 98.66% so that the L value of the microfiber leather after acid dye dyeing is 19.09;

[0059] The dyeing temperature was 90°C, the heating rate was 2°C / min, the dyeing time was 30min, and after dyeing, the temperature was lowered to 52°C and washed with water for 30min.

[0060] (2) reactive dye dyeing: placing the undried microfiber leather after acid dye dyeing in step (1) into a dyeing solution with a concentration of 0.024 wt % reactive dye in a 1:12 bath ratio, and controlling the reactive dye uptake to be 0.12 times the acid dye uptake;

[0061] The dyeing temperature was 90°C, the heating rate was 0.5°C / min, the dyeing time was 60min, and the temperature was lowered to 52°C after the dyeing was completed;

[0062] (3) Alkali washing: After dyeing, use a 0.2 g / L soda ash solution according to the bath ratio of reactive dyeing, and wash at 52°C for 28 minutes to obtain a dark-dyed microfiber leather with high color fastness.

[0063] The L value of the finally obtained high color fastness dark dyed microfiber leather is 19.25, and the color migration grade is 4.5.

[0064] Example 3

[0065] A dyeing method for deep-dyed microfiber leather with high color fastness, the specific steps are as follows:

[0066] (1) Acid dye dyeing: The nylon microfiber leather 1 is placed in a dye solution with an acid dye concentration of 0.60 wt % at a bath ratio of 1:15, and the acid dye uptake rate is adjusted to 98.36% so that the L value of the microfiber leather after acid dye dyeing is 17.38;

[0067] The dyeing temperature was 92°C, the heating rate was 0.5°C / min, the dyeing time was 40min, and after the dyeing was completed, the temperature was lowered to 55°C and washed with water for 30min.

[0068] (2) reactive dye dyeing: placing the undried microfiber leather after acid dye dyeing in step (1) into a dyeing solution with a concentration of 0.037 wt % reactive dye in a 1:14 bath ratio, and controlling the reactive dye uptake to be 0.14 times the acid dye uptake;

[0069] The dyeing temperature was 93°C, the heating rate was 2°C / min, the dyeing time was 40min, and the temperature was lowered to 55°C after the dyeing was completed;

[0070] (3) Alkali washing: After dyeing, use a 0.3 g / L soda ash solution according to the bath ratio of reactive dyeing, and wash at 55°C for 25 minutes to obtain a dark-dyed microfiber leather with high color fastness.

[0071] The L value of the finally obtained high color fastness dark dyed microfiber leather is 17.65, and the color migration grade is 4.

[0072] Example 4

[0073] A dyeing method for deep-dyed microfiber leather with high color fastness, the specific steps are as follows:

[0074] (1) Acid dye dyeing: The nylon microfiber leather 2 was placed in a dye solution with an acid dye concentration of 0.85 wt % at a bath ratio of 1:18, and the acid dye uptake was adjusted to 98.14% so that the L value of the microfiber leather after acid dye dyeing was 16.09;

[0075] The dyeing temperature was 95°C, the heating rate was 1.5°C / min, the dyeing time was 50min, and after dyeing, the temperature was lowered to 58°C and washed with water for 30min.

[0076] (2) reactive dye dyeing: placing the undried microfiber leather after acid dye dyeing in step (1) into a dyeing solution with a concentration of 0.079 wt % reactive dye in a bath ratio of 1:18, and controlling the reactive dye uptake to be 0.17 times the acid dye uptake;

[0077] The dyeing temperature was 96°C, the heating rate was 1.2°C / min, the dyeing time was 30min, and the temperature was lowered to 57°C after the dyeing was completed;

[0078] (3) Alkali washing: After dyeing, use a 0.4 g / L soda ash solution according to the bath ratio of reactive dyeing, and wash at 58°C for 22 minutes to obtain a dark-dyed microfiber leather with high color fastness.

[0079] The L value of the finally obtained high color fastness dark dyed microfiber leather is 16.28, and the color migration grade is 4.

[0080] Example 5

[0081] A dyeing method for deep-dyed microfiber leather with high color fastness, the specific steps are as follows:

[0082] (1) Acid dye dyeing: The nylon microfiber leather 3 was placed in a dye solution with an acid dye concentration of 1.00 wt% at a bath ratio of 1:20, and the acid dye uptake was adjusted to 98% so that the L value of the microfiber leather after acid dye dyeing was 15.35;

[0083] The dyeing temperature was 100°C, the heating rate was 0.5°C / min, the dyeing time was 60min, and after dyeing, the temperature was lowered to 60°C and washed with water for 30min.

[0084] (2) reactive dye dyeing: placing the undried microfiber leather after acid dye dyeing in step (1) into a dyeing solution with a concentration of 0.099 wt % reactive dye in a 1:20 bath ratio, and controlling the reactive dye uptake to be 0.2 times the acid dye uptake;

[0085] The dyeing temperature was 100°C, the heating rate was 1.6°C / min, the dyeing time was 50min, and the temperature was lowered to 60°C after the dyeing was completed;

[0086] (3) Alkali washing: After dyeing, use a 0.5 g / L soda ash solution according to the bath ratio of reactive dyeing, and wash at 60°C for 20 minutes to obtain a dark-dyed microfiber leather with high color fastness.

[0087] The L value of the finally obtained high color fastness dark dyed microfiber leather is 15.54, and the color migration grade is 4.

Claims

1. A dyeing method for a deep-dyeing type microfiber leather with high color fastness, wherein the main components of the microfiber leather are solvent-based polyurethane and nylon microfiber, characterized in that The steps include: (1) Acid dye dyeing: The microfiber leather is placed in an acid dye dye solution, and the acid dye uptake rate is adjusted so that the L value of the microfiber leather after acid dye dyeing is less than 22; (2) dyeing with reactive dyes: placing the undried microfiber leather after dyeing with acid dyes in step (1) into a dyeing solution of reactive dyes, and controlling the dyeing rate of reactive dyes to be 0.1 to 0.2 times that of acid dyes; (3) Alkali washing: After dyeing, use a soda ash solution with a concentration of 0.1-0.5 g / L according to the bath ratio of reactive dyeing, and wash at 50-70°C for 20-30 minutes to obtain a dark-dyed microfiber leather with high color fastness.

2. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 1, characterized in that: The mass ratio of solvent-based polyurethane to nylon microfiber in microfiber leather is 3:7 to 4:

6.

3. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 1, characterized in that: The L value of deep-dyed microfiber leather with high color fastness is less than 22, and the color migration grade is above level 4.

4. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 1, characterized in that: In step (1), the dye liquor concentration of the acid dye is 0.25-1.0wt%, the bath ratio is 1:10-20, and the dyeing rate of the acid dye is 98-99%.

5. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 4, characterized in that: In step (1), the dyeing temperature is 85-100° C., the heating rate is 0.5-2° C. / min, the dyeing time is 20-60 min, and after dyeing, the temperature is lowered to 50-60° C. and washed with water.

6. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 1, characterized in that: In step (2), the concentration of the dye solution of the reactive dye is 0.005-0.099wt%, and the bath ratio is 1:10-20.

7. The dyeing method of a deep-dyed microfiber leather with high color fastness according to claim 5, characterized in that: In step (2), the dyeing temperature is 85-100° C., the heating rate is 0.5-2° C. / min, the dyeing time is 20-60 min, and the temperature is lowered to 50-60° C. after the dyeing is completed.