Preparation method of aqueous polyurethane suede superfine leather

Abstract

The present invention belongs to the technical field of superfine fiber synthetic leather. The present invention discloses an aqueous polyurethane suede superfine fiber leather and a preparation method thereof. The aqueous polyurethane suede superfine fiber leather disclosed by the present invention uses irregular island-in-sea fibers or regular island-in-sea fibers, and the superfine fiber non-woven fabric made by opening, carding, web laying, pre-needling by a pre-needling machine and needling by a needling machine as the base fabric, and uses an aqueous polyurethane slurry as the impregnation slurry, and is prepared through processes of impregnation, squeezing out, drying, alkali weight reduction, re-drying, dyeing, sanding and re-drying. The suede superfine fiber leather obtained by the preparation method of the present invention has a plump, delicate and good softness hand feeling, and has excellent properties such as water resistance, antibacterial property, air permeability, yellowing resistance, wear resistance, graffiti resistance and mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of superfine fiber synthetic leather, and particularly relates to a waterborne polyurethane suede superfine fiber leather and a preparation method thereof. Background Art

[0002] The superfine fiber polyurethane synthetic leather (superfine fiber leather) is the third-generation artificial leather product. The superfine fiber leather is made of a non-woven fabric with a three-dimensional network structure prepared from superfine fibers, and at the same time has a polyurethane elastomer network structure. The superfine fiber leather truly realizes the simulation of the structural form of natural leather, and is superior to natural leather in terms of strength, comfort, air permeability and moisture permeability, chemical resistance, wrinkle resistance, abrasion resistance, processability adaptability, and quality uniformity. It is the best product to replace natural leather. Some enterprises are developing leather for military uniforms, gloves, and military boots. Among them, the suede leather of superfine fiber military gloves and the veneer leather of superfine fiber military gloves have passed the inspection of the Quality Inspection Center for Special Clothing of the Chinese People's Liberation Army, and their products have broad application prospects in the military field.

[0003] At present, the superfine fiber leather mainly uses island-type (polyethylene / polyamide 6 or polyester / water-soluble polyester) superfine fiber non-woven fabric as the reinforcing material and solvent-based polyurethane as the matrix. During the delamination and leather-making processes, it will inevitably cause pollution and residue of organic solvents such as toluene and dimethylformamide, bringing serious environmental hazards and severely restricting the development of the superfine fiber leather industry in China.

[0004] Waterborne polyurethane (WPU) uses water as the dispersion medium and has the advantages of environmental protection such as non-toxicity and low VOC. It has become an ideal substitute for traditional solvent-based polyurethane in the synthetic leather industry. Replacing solvent-based polyurethane with waterborne polyurethane resin is an inevitable trend in the future development of the superfine fiber leather industry. It can not only improve the grade of superfine fiber leather, but also change the pollution status of the superfine fiber leather industry from the source and achieve a breakthrough in the clean production of superfine fiber leather. However, at present, there are significant differences in the performance of domestic waterborne polyurethane superfine fiber leather in various aspects compared with that of foreign enterprises. Summary of the Invention

[0005] In view of this, the present invention provides a high-performance waterborne polyurethane suede superfine fiber leather and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A waterborne polyurethane suede superfine fiber leather is prepared by using indefinite-island or definite-island island fibers, opening, carding, laying, pre-punching by a pre-punching machine and punching by a punching machine to form a superfine fiber non-woven fabric as the base fabric, using a waterborne polyurethane slurry as the impregnating slurry, and through the processes of impregnation, squeezing out, drying, alkali delamination, re-drying, dyeing, sanding, and re-drying.

[0008] In a further technical solution of the present invention, the specific preparation steps of the above-mentioned aqueous polyurethane suede superfine leather are as follows:

[0009] Step 1: Spinning of sea-island fibers

[0010] Spinning irregular island sea-island fibers with PA6 as the island component and LDPE as the sea component; or spinning regular island sea-island fibers with A6 as the island component and LDPE as the sea component;

[0011] Step 2: Production of ultra-fine fiber non-woven fabric

[0012] Select the above-mentioned irregular island sea-island fibers or regular island sea-island fibers, and make them into ultra-fine fiber non-woven fabric through opening, carding, web laying, pre-needling by a pre-needling machine and needling by a needling machine;

[0013] Step 3: Shaping of ultra-fine fiber non-woven fabric

[0014] Under the temperature condition of 110°C - 160°C, thermally shape the prepared ultra-fine fiber non-woven fabric and set it aside;

[0015] Step 4: Preparation of aqueous polyurethane slurry

[0016] Mix the modified aqueous polyurethane emulsion, additives, cellulose nanocrystals and fillers, and then put them into a homogenizer to prepare a homogeneous viscous liquid, that is, obtain the aqueous polyurethane slurry for standby;

[0017] Step 5: Impregnation of ultra-fine fiber non-woven fabric

[0018] First, heat the aqueous polyurethane slurry to 45 - 50°C, and then fully immerse the ultra-fine fiber non-woven fabric prepared in Step 3 in the aqueous polyurethane slurry;

[0019] Step 6: Squeezing out

[0020] Ultrasonically treat the ultra-fine fiber non-woven fabric impregnated with the aqueous polyurethane slurry for 5 - 10 min, and then repeatedly roll it to obtain the impregnated ultra-fine fiber non-woven fabric;

[0021] Step 7: Oven drying

[0022] Put the impregnated ultra-fine fiber non-woven fabric into an oven at 120°C and dry it for 1 h to obtain semi-finished product A;

[0023] Step 8: Alkali weight reduction

[0024] Put the semi-finished product into an alkali weight reduction machine for alkali weight reduction treatment, where the alkali is sodium hydroxide with a concentration of 10%, and repeatedly boil and squeeze it at 85 - 100°C for 30 - 50 min to obtain semi-finished product B;

[0025] Step 9: Water washing and drying

[0026] Wash the semi-finished product B repeatedly with hot water at 90 - 100 °C until the washing liquid is neutral; then place it in an oven at 70 °C for sufficient drying to obtain semi-finished product C;

[0027] Step Ten: Dyeing

[0028] Put the semi-finished product C into a dyeing machine, add a colorant, and dye at a temperature of 90 - 95 °C for 60 - 120 min. After dyeing, carry out water washing to obtain semi-finished product D;

[0029] Step Eleven: Sueding

[0030] Use a sueding machine to double-side grind the semi-finished product D, and then use a brush flocking machine to raise the nap to obtain semi-finished product E;

[0031] Step Twelve: Drying and Shaping

[0032] Place the semi-finished product E in an oven at a temperature of 100 - 150 °C for drying and shaping, and then the finished waterborne polyurethane suede superfine leather is obtained.

[0033] In a further technical solution of the present invention, the ultrafine fiber non-woven fabric is pretreated before impregnation. The specific pretreatment steps are as follows:

[0034] ① Acidlyze the ultrafine fiber non-woven fabric in a citric acid solution with a volume fraction of 8% for 30 min, take it out, and dry it to obtain acidified ultrafine fiber non-woven fabric;

[0035] ② Add the acidified ultrafine fiber non-woven fabric to a fatliquoring agent with a mass fraction of 20% and oscillate it in an oscillator for 30 min to obtain pretreated ultrafine fiber non-woven fabric.

[0036] In a further technical solution of the present invention, the preparation method of the fatliquoring agent is as follows: Mix phlorotannins, thymol, carvacrol, Span 80, and sulfonated succinylated fatty acid glycerol ester in a weight ratio of 1:1:1:2:4, stir evenly, then raise the temperature to 50 °C and react for 10 min. Then add deionized water and Tween 80, and stir the emulsion with a high-speed homogenizer at 18000 rpm for 10 min. During the homogenization process, adjust the pH of the emulsion to pH 7 to obtain the fatliquoring agent.

[0037] In a further technical solution of the present invention, the waterborne polyurethane slurry comprises the following components in parts by weight: 80 - 150 parts of modified waterborne polyurethane emulsion, 1 - 10 parts of an auxiliary agent, 1 - 10 parts of cellulose nanocrystals, and 10 - 20 parts of a filler.

[0038] In a further technical solution of the present invention, the filler is 8 - 15 parts of calcium carbonate and 2 - 5 parts of modified graphene oxide by weight.

[0039] In a further technical solution of the present invention, the auxiliary agent is selected from one or more of a thickener, a wetting agent, a foaming agent, a foam stabilizer or a dispersant.

[0040] In a further technical solution of the present invention, the raw materials and dosages of the thickener, the wetting agent, the foaming agent, the foam stabilizer or the dispersant can be obtained by those skilled in the art through reasonable analysis, and will not be elaborated herein.

[0041] In a further technical solution of the present invention, the colorant is not particularly limited, and those skilled in the art can select the required colorant according to actual needs.

[0042] In a further technical solution of the present invention, the modified graphene oxide is: graphene oxide modified with 5-amino-1,10-phenanthroline.

[0043] In a further technical solution of the present invention, the preparation method of the modified aqueous polyurethane emulsion: Add isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, acetone and dibutyltin dilaurate into a reactor and stir evenly. React under the condition of 95°C. When the reaction reaches 100 min, the reaction temperature is lowered to 70°C. Add vegetable oil and chitosan-zinc oxide nanoparticles and stir evenly. Continue to react for 2 h. Cool down to 45°C and add triethylamine and react for 30 min. Then, high-speed emulsify with deionized water and remove acetone by vacuum distillation to obtain a modified aqueous polyurethane emulsion with a solid content of 30%.

[0044] In a further technical solution of the present invention, the weight ratio of the isophorone diisocyanate, the polytetrahydrofuran diol, the 2,2-dimethylolpropionic acid, the vegetable oil and the chitosan-zinc oxide nanoparticles is 5:1.6:1.2:0.4:0.4.

[0045] In a further technical solution of the present invention, the vegetable oil is one or a combination of castor oil and wupi oil.

[0046] In a further technical solution of the present invention, the vegetable oil is preferably a mixture of castor oil and wupi oil, wherein the weight ratio of castor oil to wupi oil is 2:1.

[0047] As can be seen from the above technical solutions, the present invention discloses a waterborne polyurethane suede ultra-fine fiber leather, which uses irregular island sea-island fibers or fixed island sea-island fibers, and is made into a ultra-fine fiber non-woven fabric through opening, carding, web forming, pre-needling by a pre-needling machine and needling by a needling machine. Using waterborne polyurethane slurry as the impregnating slurry, it is prepared through the processes of impregnation, squeezing out, drying, alkali weight reduction, re-drying, dyeing, sanding, and re-drying. The suede ultra-fine fiber leather obtained by the preparation method of the present invention has a plump, delicate and good softness hand feeling, and has excellent water resistance, antibacterial, breathable, yellowing resistance, wear resistance, graffiti resistance and mechanical properties. It is easy to sand during processing and has high production efficiency, making the application range of waterborne polyurethane ultra-fine fiber leather wider. At the same time, after testing, all indicators basically meet the foreign product standards.

[0048] Compared with the prior art, the present invention also has the following technical effects:

[0049] 1. The impregnating liquid of the ultra-fine fiber non-woven fabric used in the present invention uses waterborne polyurethane as the main body, replacing the solvent-based polyurethane resin, avoiding the problems of volatilization and residue of organic solvents, and achieving true clean production.

[0050] 2. Compared with the traditional ultra-fine fiber non-woven fabric directly impregnated in waterborne polyurethane slurry, the present invention performs a pretreatment step on the ultra-fine fiber non-woven fabric before impregnation. While applying a fatliquor, antibacterial substances such as thymol and phlorotannins are added, making the ultra-fine fiber non-woven fabric not only improve various properties such as the breathability, softness and comfort of the ultra-fine fiber leather, but also enhance the antibacterial performance of the ultra-fine fiber leather.

[0051] 3. Compared with the traditional waterborne polyurethane impregnating slurry, the present invention performs a modification treatment on the waterborne polyurethane emulsion. During the synthesis of waterborne polyurethane, the present invention adds vegetable oil to modify the polyurethane. Compared with the traditional castor oil added, the present invention adds a mixture of castor oil and wupi oil, solving the technical problem of poor storage stability of the waterborne polyurethane emulsion caused by the addition of single castor oil. Utilizing the polyhydroxy structure of wupi oil as a plant cross-linking agent in the reaction can fully improve the storage stability of the waterborne polyurethane slurry, and can also fully improve the water resistance and graffiti resistance of the ultra-fine fiber leather; when preparing the modified polyurethane emulsion, chitosan-zinc oxide nanoparticles are also added, which not only assist in improving the storage stability of the slurry, but also assist in improving the mechanical properties of the slurry, and further improve the flame retardant performance of the ultra-fine fiber leather.

[0052] 4. When preparing the waterborne polyurethane slurry, the present invention also adds modified graphene, which fully improves the wear resistance of the ultra-fine fiber leather; nano-cellulose crystals are also added to further improve the wear resistance of the ultra-fine fiber leather, and make the ultra-fine fiber leather feel better and softer.

[0053] 5. When the ultrafine fiber non-woven fabric is impregnated with the aqueous polyurethane slurry in the present invention, instead of the normal temperature impregnation in the past, the slurry is heated up before impregnation, which can fully improve the impregnation efficiency, enabling the slurry to penetrate more fully into the middle of the ultrafine fiber non-woven fabric. Moreover, ultrasonic treatment is carried out after impregnation, further improving the impregnation efficiency, making the slurry more evenly distributed on the ultrafine fiber non-woven fabric, making the impregnation more sufficient, and ultimately making the quality of the prepared superfine leather better. Detailed implementation manners

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] Example 1

[0056] The ultrafine fiber non-woven fabric is pretreated before impregnation. The specific pretreatment steps are as follows:

[0057] ① The ultrafine fiber non-woven fabric is acid-hydrolyzed in a citric acid solution with a volume fraction of 8% for 30 minutes, taken out, and dried to obtain the acidified ultrafine fiber non-woven fabric;

[0058] ② The preparation method of the fatliquoring emulsion is as follows: phlorotannins, thymol, thymol, Span 80 and sulfonated succinylated fatty acid glycerol ester are mixed in a weight ratio of 1:1:1:2:4 and stirred evenly, then the temperature is raised to 50 °C and reacted for 10 minutes, then deionized water and Tween 80 are added, and the emulsion is stirred with a high-speed homogenizer at 18000 rpm for 10 minutes. During the homogenization process, the pH of the emulsion is adjusted to pH 7 to obtain the fatliquoring emulsion;

[0059] ③ The acidified ultrafine fiber non-woven fabric is added to the fatliquoring emulsion with a mass fraction of 20% and oscillated in an oscillator for 30 minutes to obtain the pretreated ultrafine fiber non-woven fabric.

[0060] Example 2

[0061] Preparation method of modified aqueous polyurethane emulsion: Isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, acetone and dibutyltin dilaurate are added to a reactor and stirred evenly. The reaction is carried out at 95 °C. When the reaction reaches 100 min, the reaction temperature is reduced to 70 °C. Castor oil and chitosan-zinc oxide nanoparticles are added and stirred evenly. The reaction continues for 2 h. The temperature is reduced to 45 °C and triethylamine is added for reaction for 30 min. Then it is emulsified at high speed with deionized water. After removing acetone by vacuum distillation, a modified aqueous polyurethane emulsion with a solid content of 30% is obtained; the weight ratio of the isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, castor oil and chitosan-zinc oxide nanoparticles is 5:1.6:1.2:0.4:0.4.

[0062] Example 3

[0063] Preparation method of modified aqueous polyurethane emulsion: Isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, acetone and dibutyltin dilaurate are added to a reactor and stirred evenly. The reaction is carried out at 95 °C. When the reaction reaches 100 min, the reaction temperature is reduced to 70 °C. Vegetable oil and chitosan-zinc oxide nanoparticles are added and stirred evenly. The reaction continues for 2 h. The temperature is reduced to 45 °C and triethylamine is added for reaction for 30 min. Then it is emulsified at high speed with deionized water. After removing acetone by vacuum distillation, a modified aqueous polyurethane emulsion with a solid content of 30% is obtained; the weight ratio of the isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, polyhydroxy wupi oil and chitosan-zinc oxide nanoparticles is 5:1.6:1.2:0.4:0.4; the vegetable oil is a mixture of castor oil and wupi oil; among them, the weight ratio of castor oil to polyhydroxy wupi oil in the mixture is 2:1.

[0064] Example 4

[0065] A preparation method of an aqueous polyurethane slurry is prepared according to the following weight parts:

[0066] 80 parts of the modified aqueous polyurethane emulsion, 1 part of an auxiliary agent, 1 part of cellulose nanocrystals and 10 parts of a filler are mixed and then placed in a homogenizer to prepare a homogeneous viscous liquid, thus obtaining the aqueous polyurethane slurry for standby; among them, the filler is 8 parts of calcium carbonate and 2 parts of modified graphene oxide by weight; among them, the preparation method of the modified polyurethane is the same as that of Example 3; among them, the 100% modulus of the polyurethane film is 4.1 MPa.

[0067] Example 5

[0068] A preparation method of an aqueous polyurethane slurry is prepared according to the following weight parts:

[0069] Mix 150 parts of modified aqueous polyurethane emulsion, 10 parts of additives, 10 parts of cellulose nanocrystals and 20 parts of filler, and then place the mixture in a homogenizer to prepare a homogeneous viscous liquid, thus obtaining the aqueous polyurethane slurry for standby; among them, the filler is 15 parts of calcium carbonate and 5 parts of modified graphene oxide by weight; among them, the preparation method of the modified polyurethane is the same as that in Example 3; among them, the 100% modulus of the polyurethane film is 4.0 MPa.

[0070] Example 6

[0071] A preparation method of an aqueous polyurethane slurry is formulated according to the following weight parts:

[0072] Mix 100 parts of modified aqueous polyurethane emulsion, 5 parts of additives, 7 parts of cellulose nanocrystals and 15 parts of filler by weight, and then place the mixture in a homogenizer to prepare a homogeneous viscous liquid, thus obtaining the aqueous polyurethane slurry for standby; among them, the filler is 11.5 parts of calcium carbonate and 3.5 parts of modified graphene oxide by weight; among them, the preparation method of the modified polyurethane is the same as that in Example 3; among them, the 100% modulus of the polyurethane film is 4.5 MPa.

[0073] Example 7

[0074] A preparation method of an aqueous polyurethane slurry is formulated according to the following weight parts:

[0075] Mix 100 parts of modified aqueous polyurethane emulsion, 5 parts of additives, 7 parts of cellulose nanocrystals and 15 parts of filler by weight, and then place the mixture in a homogenizer to prepare a homogeneous viscous liquid, thus obtaining the aqueous polyurethane slurry for standby; among them, the filler is 11.5 parts of calcium carbonate and 3.5 parts of modified graphene oxide by weight; among them, the preparation method of the modified polyurethane is the same as that in Example 2; among them, the 100% modulus of the polyurethane film is 4.1 MPa.

[0076] Example 8

[0077] The specific preparation steps of an aqueous polyurethane suede superfine leather are as follows:

[0078] Step 1: Spinning of sea-island fibers

[0079] Spun irregular island sea-island fibers according to the mass ratio of PA6 to LDPE of 50:50.

[0080] Step 2: Production of ultrafine fiber non-woven fabric

[0081] Select the above-mentioned irregular island sea-island fibers, and make them into ultrafine fiber non-woven fabric through opening, carding, web laying, pre-needling by a pre-needling machine and leaf needling by a needling machine.

[0082] Step 3: Shaping of the ultrafine fiber non-woven fabric

[0083] Under the temperature condition of 110 °C, thermally set the prepared ultrafine fiber non-woven fabric for later use;

[0084] Step Four: Prepare the aqueous polyurethane sizing

[0085] Prepare it according to the preparation method of the aqueous polyurethane sizing described in Example 4;

[0086] Step Five: Impregnation of the ultrafine fiber non-woven fabric

[0087] First, heat the aqueous polyurethane sizing to 45 °C, and then pre-treat the ultrafine fiber non-woven fabric prepared in Step Three according to the pre-treatment steps described in Example 1 and then fully immerse it in the aqueous polyurethane sizing;

[0088] Step Six: Squeezing out

[0089] Ultrasonically treat the ultrafine fiber non-woven fabric impregnated with the aqueous polyurethane sizing for 5 minutes, and then repeatedly roll it to obtain the impregnated ultrafine fiber non-woven fabric;

[0090] Step Seven: Oven drying

[0091] Put the impregnated ultrafine fiber non-woven fabric into an oven at 120 °C and dry it for 1 hour to obtain semi-finished product A;

[0092] Step Eight: Alkali weight reduction

[0093] Perform alkali weight reduction treatment on the semi-finished product in an alkali weight reduction machine, where the alkali is sodium hydroxide with a concentration of 10%, and repeatedly boil and extrude it at 85 °C for 30 minutes to obtain semi-finished product B;

[0094] Step Nine: Washing and drying

[0095] Wash the semi-finished product B repeatedly with hot water at 90 °C until the washing liquid is neutral; then place it in an oven at 70 °C and fully dry it to obtain semi-finished product C;

[0096] Step Ten: Dyeing

[0097] Put the semi-finished product C into a dyeing machine, add a colorant, and dye it at 90 °C for 60 minutes. After dyeing, wash it with water to obtain semi-finished product D;

[0098] Step Eleven: Raising

[0099] Use a raising machine to double-side grind the semi-finished product D, and then use a brush flocking machine to flock it to obtain semi-finished product E;

[0100] Step Twelve: Drying and shaping

[0101] Place the semi-finished product E in an oven at 100 °C for drying and shaping to obtain the finished aqueous polyurethane suede ultra-fine leather.

[0102] Example 9

[0103] The specific preparation steps of a waterborne polyurethane suede superfine leather are as follows:

[0104] Step 1: Spinning of sea-island fibers

[0105] Spinning out fixed-island sea-island fibers according to the mass ratio of A6 to LDPE of 50:50;

[0106] Step 2: Production of ultra-fine fiber non-woven fabric

[0107] Selecting the above-mentioned fixed-island sea-island fibers, and making them into ultra-fine fiber non-woven fabric through opening, carding, web laying, pre-needling by a pre-needling machine and needle punching by a needle punching machine;

[0108] Step 3: Shaping of ultra-fine fiber non-woven fabric

[0109] Under the temperature condition of 160 °C, thermally shaping the produced ultra-fine fiber non-woven fabric for standby;

[0110] Step 4: Preparation of waterborne polyurethane slurry

[0111] Preparing according to the preparation method of the waterborne polyurethane slurry described in Example 5;

[0112] Step 5: Impregnation of ultra-fine fiber non-woven fabric

[0113] First, heating the waterborne polyurethane slurry to 50 °C, and then pre-treating the ultra-fine fiber non-woven fabric prepared in Step 3 according to the pre-treatment steps described in Example 1 and then fully impregnating it in the waterborne polyurethane slurry;

[0114] Step 6: Squeezing out

[0115] Subjecting the ultra-fine fiber non-woven fabric impregnated with the waterborne polyurethane slurry to ultrasonic treatment for 10 min, and then repeatedly rolling it to obtain the impregnated ultra-fine fiber non-woven fabric;

[0116] Step 7: Oven drying

[0117] Putting the impregnated ultra-fine fiber non-woven fabric into an oven at a temperature of 120 °C and drying it for 1 h to obtain semi-finished product A;

[0118] Step 8: Alkali weight reduction

[0119] Subjecting the semi-finished product to alkali weight reduction treatment in an alkali weight reduction machine, where the alkali is sodium hydroxide with a concentration of 10%, and repeatedly boiling and extruding it at 100 °C for 50 min to obtain semi-finished product B;

[0120] Step 9: Washing and drying

[0121] Wash the semi-finished product B repeatedly with hot water at 100 °C until the washing liquid is neutral; then place it in an oven at 70 °C for sufficient drying to obtain semi-finished product C;

[0122] Step Ten: Dyeing

[0123] Put the semi-finished product C into a dyeing machine, add a colorant, and dye it at a temperature of 95 °C for 120 minutes. After dyeing, wash it with water to obtain semi-finished product D;

[0124] Step Eleven: Raising

[0125] Use a raising machine to double-side grind the semi-finished product D, and then use a brush raising machine to raise the nap to obtain semi-finished product E;

[0126] Step Twelve: Drying and Shaping

[0127] Place the semi-finished product E in an oven at a temperature of 150 °C for drying and shaping, and then the finished waterborne polyurethane suede superfine leather is obtained.

[0128] Example 10

[0129] The specific preparation steps of a waterborne polyurethane suede superfine leather are as follows:

[0130] Step One: Spinning of Sea-island Fibers

[0131] Spinning out fixed-island sea-island fibers according to the mass ratio of A6 to LDPE of 50:50;

[0132] Step Two: Production of Microfiber Nonwoven Fabric

[0133] Select the above-mentioned fixed-island sea-island fibers, and make microfiber nonwoven fabric through opening, carding, web laying, pre-punching by a pre-punching machine and punching by a punching machine;

[0134] Step Three: Shaping of Microfiber Nonwoven Fabric

[0135] Under the temperature condition of 150 °C, thermally shape the produced microfiber nonwoven fabric for standby;

[0136] Step Four: Preparation of Waterborne Polyurethane Slurry

[0137] Prepare according to the preparation method of the waterborne polyurethane slurry described in Example 6;

[0138] Step Five: Impregnation of Microfiber Nonwoven Fabric

[0139] First, heat the waterborne polyurethane slurry to 50 °C, and then pre-treat the microfiber nonwoven fabric prepared in Step Three according to the pre-treatment steps described in Example 1 and then fully immerse it in the waterborne polyurethane slurry;

[0140] Step Six: Squeezing out

[0141] The ultrafine fiber non-woven fabric impregnated with the aqueous polyurethane slurry is ultrasonically treated for 8 minutes and then repeatedly rolled to obtain the impregnated ultrafine fiber non-woven fabric;

[0142] Step Seven: Oven drying

[0143] The impregnated ultrafine fiber non-woven fabric is placed in an oven at a temperature of 120 °C and dried for 1 h to obtain semi-finished product A;

[0144] Step Eight: Alkali weight reduction

[0145] The semi-finished product is placed in an alkali weight reduction machine for alkali weight reduction treatment. The alkali is sodium hydroxide with a concentration of 10%. It is repeatedly alkali-boiled and extruded at 95 °C for 40 min to obtain semi-finished product B;

[0146] Step Nine: Water washing and drying

[0147] The semi-finished product B is repeatedly washed with hot water at 95 °C until the washing liquid is neutral; then it is placed in an oven at 70 °C and fully dried to obtain semi-finished product C;

[0148] Step Ten: Dyeing

[0149] The semi-finished product C is put into a dyeing machine, a colorant is added, and it is dyed at a temperature of 95 °C for 100 min. After dyeing, it is washed with water to obtain semi-finished product D;

[0150] Step Eleven: Raising

[0151] The semi-finished product D is double-sided polished by a raising machine, and then raised by a brush raising machine to obtain semi-finished product E;

[0152] Step Twelve: Drying and shaping

[0153] The semi-finished product E is placed in an oven at a temperature of 120 °C for drying and shaping to obtain the finished aqueous polyurethane suede ultra-fine leather.

[0154] The various ultra-fine leathers prepared in Examples 4-7 above are tested for performance with aqueous polyurethane, and the performance data are compared with those of conventional aqueous polyurethane. The reference data for each performance test are shown in Table 1.

[0155] The ultra-fine leathers prepared in Examples 8-10 above are tested for performance, and the performance data are compared with those of solvent-based polyurethane ultra-fine leather and genuine leather. The reference data for each performance test are shown in Table 2.

[0156] Table 1

[0157]

[0158] From the comparison of the performance data of the aqueous polyurethane for microfiber leather provided by each embodiment of the present invention shown in Table 1 with those of conventional aqueous polyurethanes, it can be seen that, compared with conventional aqueous polyurethanes, the aqueous polyurethane for microfiber leather prepared in the present invention has lower water absorption rate, high storage stability and excellent mechanical properties.

[0159] Table 2

[0160]

[0161] From the comparison of the performance data of the microfiber leather provided by each embodiment of the present invention shown in Table 2 with those of solvent-based polyurethane microfiber leather and genuine leather, it can be seen that, compared with solvent-based polyurethane microfiber leather and genuine leather, the microfiber leather prepared in the present invention has more excellent water-wet breathability, water resistance, abrasion resistance, antibacterial property and mechanical properties.

[0162] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0163] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a waterborne polyurethane suede synthetic leather, successively comprising the following steps: Spinning of sea-island fiber, production of ultra-fine fiber non-woven fabric, shaping of ultra-fine fiber non-woven fabric, preparation of aqueous polyurethane sizing agent, impregnation of ultra-fine fiber non-woven fabric, squeezing, oven drying, alkali weight reduction, water washing and drying, dyeing, raising and drying and shaping, characterized in that: For the preparation of the aqueous polyurethane sizing agent: mix the modified aqueous polyurethane emulsion, additives, cellulose nanocrystals and fillers, and then place them in a homogenizer to prepare a homogeneous viscous liquid, that is, obtain the aqueous polyurethane sizing agent for standby; For the impregnation of the ultra-fine fiber non-woven fabric: first heat the aqueous polyurethane sizing agent to 45-50 °C, and then fully immerse the ultra-fine fiber non-woven fabric in the aqueous polyurethane sizing agent; For the squeezing: ultrasonically treat the ultra-fine fiber non-woven fabric impregnated with the aqueous polyurethane sizing agent for 5-10 min, and then repeatedly roll it to obtain the impregnated ultra-fine fiber non-woven fabric; The aqueous polyurethane sizing agent described above comprises the following components in parts by weight: 80-150 parts of modified aqueous polyurethane emulsion, 1-10 parts of additives, 1-10 parts of cellulose nanocrystals and 10-20 parts of fillers; The filler described above is 8-15 parts of calcium carbonate and 2-5 parts of modified graphene oxide by weight; The preparation method of the modified aqueous polyurethane emulsion: add isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, acetone and dibutyltin dilaurate into a reactor and stir evenly, react under the condition of 95 °C. When the reaction time reaches 100 min, the reaction temperature is reduced to 70 °C, add vegetable oil and chitosan-zinc oxide nanoparticles and stir evenly, continue to react for 2 h, cool down to 45 °C and add triethylamine to react for 30 min, and then use deionized water for high-speed emulsification. After distilling off acetone under reduced pressure, a modified aqueous polyurethane emulsion with a solid content of 30% is obtained; The vegetable oil described above is a mixture of castor oil and wupi oil, wherein the weight ratio of castor oil to wupi oil is 2:

1.

2. The preparation method of a waterborne polyurethane suede ultra-fine leather according to claim 1, characterized in that: Before impregnation, the ultra-fine fiber non-woven fabric is pre-treated, and the specific pre-treatment steps are: ① Put the ultra-fine fiber non-woven fabric into a citric acid solution with a volume fraction of 8% for acidolysis for 30 min, take it out and dry it to obtain the acidified ultra-fine fiber non-woven fabric; ② Add the acidified ultra-fine fiber non-woven fabric into a fatliquoring agent with a mass fraction of 20% and oscillate it in an oscillator for 30 min to obtain the pre-treated ultra-fine fiber non-woven fabric.

3. The preparation method of a waterborne polyurethane suede synthetic leather according to claim 2, characterized in that: The preparation method of the fatliquoring agent is: mix phlorotannins, thymol, thymol, Span 80 and sulfonated succinylated fatty acid glycerol ester in a weight ratio of 1:1:1:2:4 and stir evenly, then raise the temperature to 50 °C and react for 10 min, then add deionized water and Tween 80, and use a high-speed homogenizer to stir the emulsion at 18,000 rpm for 10 min. During the homogenization process, adjust the pH value of the emulsion to 7 to obtain the fatliquoring agent.

4. The preparation method of a waterborne polyurethane suede ultra-fine leather according to claim 1, characterized in that: The modified graphene oxide described above is: graphene oxide modified by 5-amino-1,10-phenanthroline.

5. The preparation method of a waterborne polyurethane suede superfine leather according to claim 1, characterized in that: The additives are selected from one or more of thickeners, wetting agents, foaming agents, foam stabilizers or dispersants.

6. The preparation method of a waterborne polyurethane suede superfine leather according to claim 1, characterized in that: The weight ratio of the isophorone diisocyanate, polytetrahydrofuran diol, 2,2-dimethylolpropionic acid, vegetable oil and chitosan-zinc oxide nanoparticles is 5: 1.6：1.2：0.4：0.4。

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