Preparation method of a kind of soft artificial leather

Abstract

The present invention discloses a preparation method of a soft artificial leather, comprising: preparing a first sea-island type ultrafine fiber and a second sea-island type ultrafine fiber by composite spinning → preparing a base fabric → first weight reduction → resin compounding and curing → second weight reduction → post-finishing. The present invention adopts two-step weight reduction treatment. The purpose of the first weight reduction is to expose part of the ultrafine fibers to increase the contact area between the fibers and the resin slurry, thereby improving the bonding tightness between the fibers and the resin, and further improving the breaking strength and resilience of the artificial leather; the purpose of the second weight reduction is to enhance the fluffiness, softness, air permeability and moisture permeability of the ultrafine fiber synthetic leather. Therefore, the artificial leather prepared by the present invention can take into account strength, softness, elasticity and air permeability and moisture permeability, and has good comprehensive properties.

Description

Technical Field

[0001] The present invention belongs to the field of artificial leather manufacturing, and particularly relates to a method for preparing a soft artificial leather. Background Art

[0002] Microfiber synthetic leather is a new type of high-grade artificial leather made of extremely fine fibers. It is prepared by blending or compound spinning of sea component and island component polymers, then processed into non-woven fabric by non-woven process, and then impregnated and solidified with polyurethane, and the sea component is removed by weight reduction and fiber opening to obtain a microfiber leather base fabric with a triple helix structure similar to that of natural leather collagen fibers. Finally, high-fidelity leather products are obtained by coating or laminating. Microfiber synthetic leather has become a high-grade substitute for natural leather with its high physical properties, durability and softness, and is widely used in various fields such as clothing, shoes, luggage, furniture, and automotive interiors. The voids left after the sea component of the sea-island fiber is reduced in weight produce a "release" effect between the island component and polyurethane, which can greatly improve the fluffiness, softness, air permeability and moisture permeability of microfiber synthetic leather. However, at present, microfiber synthetic leather has problems such as poor resilience, low breaking strength and low softness, which limit its application in fields such as boot shafts and clothing.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The present invention provides a method for preparing a soft artificial leather, aiming to provide a soft artificial leather with good resilience and high breaking strength.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing a soft artificial leather includes the following steps:

[0007] Step 1: Prepare first sea-island type microfibers and second sea-island type microfibers respectively by composite spinning method. Among them, the first sea-island type microfibers include a first island component and a first sea component; the second sea-island type microfibers include a second island component and a second sea component;

[0008] Step 2: Blend the first sea-island type microfibers and the second sea-island type microfibers to obtain a composite fiber yarn, and then braid to form a base fabric;

[0009] Step 3: Put the base fabric into a treating agent solution for the first weight reduction, aiming to remove the second sea component, that is, to obtain a partially weight-reduced base fabric;

[0010] Step 4: Use the scraping method to perform resin compounding on the partially weight-reduced base fabric, and obtain a sea-island super fiber leather precursor after heating and curing;

[0011] Step Five: Place the sea-island microfiber leather precursor in a weight reduction treatment solution for a second weight reduction, then wash with water and dry to obtain an ultrafine fiber synthetic leather base fabric;

[0012] Step Six: After the ultrafine fiber synthetic leather base fabric is processed by at least one post-treatment process including dry laminating, surface treatment, polishing, embossing, water kneading, and calendering, a soft artificial leather is obtained.

[0013] In some embodiments of the present invention, the second sea component is a water-soluble spinnable polymer or a composition containing a water-soluble spinnable polymer.

[0014] In some embodiments of the present invention, the first island component and the second island component are independently selected from one of the following: polyamide or its derivatives, polyester or its derivatives; wherein, the polyamide or its derivatives include at least one of polyamide 6, polyamide 56, polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515, polyamide 516, or a polyamide-based copolymer; preferably polyamide 6, polyamide 56; the polyester or its derivatives include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, or a copolymer of the above polyesters; the polyethylene includes high-density polyethylene, etc.

[0015] In some embodiments of the present invention, the second sea component includes at least one of polyvinylpyrrolidone or its composition, polyvinyl alcohol or its composition.

[0016] In some embodiments of the present invention, the first sea component includes at least one of polyester or its derivatives, polyurethane or its derivatives; wherein, the polyester or its derivatives include at least one of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, or a copolymer of the above polyesters, high-shrinkage polyester (HSPET), water-soluble multi-component copolyester (COPET); the polyurethane or its derivatives include at least one of aqueous polyurethane, elastic polyurethane.

[0017] In some embodiments of the present invention, the mass ratio of the first sea component to the first island component is (20:80) to (80:20), preferably (40:60) to (60:40).

[0018] In some embodiments of the present invention, the mass ratio of the second sea component to the second island component is (20:80) to (80:20), preferably (40:60) to (60:40).

[0019] In some embodiments of the present invention, the number of islands of the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber is independently 16-500, preferably, the number of islands is 37-51.

[0020] In some embodiments of the present invention, in step 2, the mass ratio of the blend of the first island-in-sea type microfiber and the second island-in-sea type microfiber is (90:10) to (50:50), preferably 70:30.

[0021] In some embodiments of the present invention, the treatment agent solution in step three is an alcohol aqueous solution of the treatment agent, and the treatment agent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, phenol, methyl salicylate, and benzenesulfonamide.

[0022] In an optional embodiment, the alcohol water refers to a mixed solution of alcohol and water, wherein the alcohol includes at least one of ethanol, ethylene glycol, propylene glycol, and glycerol; and the volume percentage of alcohol and water in the alcohol water is 10 to 30%.

[0023] In some embodiments of the present invention, the concentration of the treating agent in the treating agent solution in step three is 0.2 to 2 g / L, preferably 0.8 to 1.2 g / L.

[0024] In some embodiments of the present invention, the first reduction refers to ultrasonic treatment at room temperature for 30 to 60 minutes.

[0025] In some embodiments of the present invention, the solid content of the resin slurry in step 4 is 15% to 28%;

[0026] In some embodiments of the present invention, the resin slurry described in step 4, calculated by mass, includes the following components: 20-40 parts of polyurethane prepolymer, 5-20 parts of soy protein isolate, 0.1-0.8 parts of defoaming agent, 0.1-0.8 parts of ultraviolet absorber, 3-8g of curing agent, 0-0.6 parts of dispersant, and 70-350 parts of water.

[0027] In some embodiments of the present invention, the resin in the island microfiber leather precursor in step 4 is 40% to 70% of the weight of the partially reduced base fabric based on the dry weight of the resin slurry.

[0028] In some embodiments of the present invention, the weight reduction treatment liquid is an alkali solution. In an optional embodiment, the temperature of the weight reduction treatment liquid is 50-90° C., and the weight reduction treatment method includes but is not limited to immersion, stirring, ultrasound, roller pressing, etc.

[0029] The present invention has the following advantages and beneficial effects:

[0030] The present invention provides a method for preparing a soft artificial leather, which adopts a two-step weight reduction treatment. The first weight reduction is prior to resin compounding, aiming to expose part of the ultrafine fibers to increase the contact area between the fibers and the resin slurry, thereby improving the bonding tightness between the fibers and the resin, and further enhancing the breaking strength and resilience of the artificial leather. The second weight reduction is after resin compounding, aiming to produce a "release" effect between the island component and the polyurethane, which can greatly improve the fluffiness, softness, air permeability and moisture permeability of the ultrafine fiber synthetic leather. Therefore, the artificial leather prepared by the present invention can balance strength, softness, elasticity and air permeability and moisture permeability, and has good comprehensive properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The process flow chart of a method for preparing a soft artificial leather provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following further describes the present invention in detail with reference to specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0033] The present invention provides a method for preparing a soft artificial leather. The process route is shown in the attached Figure 1 , and includes the following steps:

[0034] Step 1: Prepare the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber respectively by the composite spinning method. Among them, the first sea-island type ultrafine fiber includes a first island component and a first sea component; the second sea-island type ultrafine fiber includes a second island component and a second sea component;

[0035] Step 2: Blend the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber to obtain a composite fiber yarn, and then weave it to form a base fabric;

[0036] Step 3: Put the base fabric into a treatment agent solution for the first weight reduction, aiming to remove the second sea component, that is, obtain a partially weight-reduced base fabric;

[0037] Step 4: Use the scraping method to perform resin compounding on the partially weight-reduced base fabric, and obtain a sea-island ultra-fiber leather precursor after heating and curing;

[0038] Step 5: Place the sea-island ultra-fiber leather precursor in a weight reduction treatment solution for the second weight reduction, then wash and dry it to obtain an ultrafine fiber synthetic leather base fabric;

[0039] Step 6: After the ultrafine fiber synthetic leather base fabric is processed by at least one post-treatment process including dry laminating, surface treatment, polishing, embossing, water kneading, and ironing, a soft artificial leather is obtained.

[0040] When preparing the base fabric of artificial leather, the present invention adds a second sea-island type ultra-fine fiber, reduces its weight before resin compounding, removes the second sea component to obtain a partially weight-reduced base fabric, greatly increases the contact area between the fibers in the base fabric and the resin slurry, thereby improving the bonding tightness between the fibers and the resin, and further improving the breaking strength and resilience of the obtained artificial leather.

[0041] The present invention adopts a two-step weight reduction treatment. The first weight reduction is prior to resin compounding, aiming to expose some ultra-fine fibers to increase the contact area between the fibers and the resin slurry, thereby improving the bonding tightness between the fibers and the resin, and further improving the breaking strength and resilience of the artificial leather; the second weight reduction is after resin compounding, aiming to produce a "release" effect between the island component and the polyurethane, which can greatly improve the fluffiness, softness, air permeability, moisture permeability and other properties of the ultra-fine fiber synthetic leather. Therefore, complete weight reduction before resin compounding or complete weight reduction after resin compounding cannot achieve the technical effects of the present invention. Complete weight reduction before resin compounding will make the artificial leather feel stiff, have a low elongation rate and poor softness; complete weight reduction after resin compounding will make the breaking strength of the artificial leather unable to be improved. Under the process of the present invention, the obtained artificial leather has good strength, softness and resilience.

[0042] In some embodiments of the present invention, the second sea component is a water-soluble spinnable polymer or a composition containing a water-soluble spinnable polymer; the water-soluble spinnable polymer has two characteristics of water solubility and spinnability. Meeting the water solubility condition enables it to be distinguished from the first sea component and can achieve weight reduction in a neutral aqueous solution environment, thereby achieving the purpose of weight reduction before resin compounding; meeting the spinnability enables it to be melt-spun with the second island component by the fixed island method using the composite spinning method; some water-soluble polymers do not meet the spinnability requirements and need to add additives to improve their spinnability. Therefore, the second sea component may be a composition containing a water-soluble spinnable polymer.

[0043] In some embodiments of the present invention, the first island component and the second island component are independently selected from one of the following: polyamide or its derivatives, polyester or its derivatives, polyethylene, polystyrene or polypropylene; wherein, the polyamide or its derivatives include at least one of polyamide 6, polyamide 56, polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515, polyamide 516 or polyamide-based copolymers; preferably polyamide 6, polyamide 56; the polyester or its derivatives include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate or copolymers of the above polyesters; the polyethylene includes high-density polyethylene, etc.

[0044] In some embodiments of the present invention, the second sea component includes at least one of polyvinylpyrrolidone or its composition, polyvinyl alcohol or its composition; both polyvinylpyrrolidone and polyvinyl alcohol are water-soluble and spinnable polymers with good water solubility; in some embodiments of the present invention, an auxiliary agent needs to be added to the second sea component to improve the spinning performance of the polymer, so the second sea component may be a composition containing polyvinylpyrrolidone or polyvinyl alcohol.

[0045] In some embodiments of the present invention, the first sea component includes at least one of polyester or its derivatives, polyurethane or its derivatives; wherein, the polyester or its derivatives include at least one of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate or copolymers of the above polyesters, high shrinkage polyester (HSPET), water-soluble multi-component copolyester (COPET); the polyurethane or its derivatives include at least one of aqueous polyurethane, elastic polyurethane.

[0046] It should be noted that although there is partial overlap in the listed types of names of the island component and the sea component, the names are general terms for such polymers, including polymers with different viscosities and specifications. Polymers with different specifications and viscosities can be used as the sea component or the island component respectively. For example, high-density polyethylene can be used as the island component, while linear low-density polyethylene can be used as the sea component; low-viscosity polyester can be used as the sea component, while high-viscosity polyester can be used as the island component; in addition, polymers of the same specification, when paired with different island or sea components, can be used as the sea or island component. For example, polyethylene as the sea component and polyamide as the island component are used for weight reduction with toluene, and polyethylene as the island component and polyester as the sea component are used for weight reduction with lye; therefore, which type of polymer is used as the sea component or the island component depends on the specific scheme.

[0047] In some embodiments of the present invention, the mass ratio of the first sea component to the first island component is (20:80) to (80:20), preferably (40:60) to (60:40).

[0048] In some embodiments of the present invention, the mass ratio of the second sea component to the second island component is (20:80) to (80:20), preferably (40:60) to (60:40).

[0049] The mass ratio of the sea component to the island component affects the mechanical properties, softness and resilience of the artificial leather. Specifically, the mass ratio of the second sea component to the second island component affects partial weight reduction, and further affects the bonding degree between the resin and the fiber, thereby affecting the mechanical properties, softness and resilience of the artificial leather; if the sea component is too high, the softness of the artificial leather will decrease; if the sea component is too low, the breaking strength and resilience of the artificial leather will decrease.

[0050] In some embodiments of the present invention, the number of islands of the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber independently takes a value of 16 to 500. Preferably, the number of islands takes a value of 37 to 51.

[0051] In some embodiments of the present invention, the mass ratio of blending the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber in step two is (90:10) to (50:50), preferably 70:30.

[0052] In some embodiments of the present invention, the treatment agent solution in step three is an alcohol aqueous solution of the treatment agent. The treatment agent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, phenol, methyl salicylate, and benzenesulfonamide. The type of the treatment agent is selected according to the type of the island component. Specifically, when the island component is polyamide or its derivative, the treatment agent is preferably N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, or benzenesulfonamide. When the island component is polyester or its derivative, the treatment agent is N-methylpyrrolidone, phenol, or methyl salicylate. When the island component is polyolefin, the treatment agent is N,N-dimethylacetamide or phenol.

[0053] In an alternative embodiment, the alcohol water refers to a mixed solution of alcohol and water. The alcohol includes at least one of ethanol, ethylene glycol, propylene glycol, and glycerol. The volume percentage of alcohol and water in the alcohol water is 10 to 30%.

[0054] In some embodiments of the present invention, the concentration of the treatment agent in the treatment agent solution in step three is 0.2 to 2 g / L, preferably 0.8 to 1.2 g / L.

[0055] The treatment agent solution provided by the present invention plays a role in partial weight reduction and plasticizing and softening the island component. Specifically, the alcohol water serves as a solvent environment for the second sea component to be dissolved out by weight reduction. According to the principle of similar phase solubility, the treatment agent can penetrate into the interior of the island component fiber to plasticize and soften it, thereby improving the softness and elasticity of the artificial leather. The type of the treatment agent and its concentration in the solution affect the performance of the artificial leather. If the concentration of the treatment agent solution is too high, the breaking strength of the artificial leather decreases. If the concentration of the treatment agent solution is too low, the softness and elongation rate of the artificial leather decrease.

[0056] In some embodiments of the present invention, the first weight reduction refers to ultrasonic treatment at room temperature for 30 to 60 minutes.

[0057] In some embodiments of the present invention, the solid content of the resin sizing agent in step four is 15% to 28%;

[0058] In some embodiments of the present invention, the resin slurry in step 4 includes the following components, calculated by weight: 20-40 parts of polyurethane prepolymer, 5-20 parts of soy protein isolate, 0.1-0.8 parts of defoaming agent, 0.1-0.8 parts of ultraviolet absorber, 3-8g of curing agent, 0-0.6 parts of dispersant, and 70-350 parts of water;

[0059] In an optional embodiment, the steps of preparing the resin slurry are as follows:

[0060] (1) mixing polyol, polyisocyanate, catalyst and hydrophilic chain extender for reaction, and finally adding neutralizing agent for neutralization to obtain polyurethane prepolymer;

[0061] (2) adding a dispersant and soy protein isolate to the polyurethane prepolymer, stirring evenly, and then adding deionized water and a curing agent to obtain a soy protein modified polyurethane emulsion;

[0062] (3) adding a defoaming agent and an ultraviolet absorber to the soy protein modified polyurethane emulsion, and adding deionized water to adjust the solid content, thereby obtaining a protein modified polyurethane slurry.

[0063] In an optional embodiment, the molar ratio of the polyether polyol, the hydrophilic chain extender and the polyisocyanate is 1:(1-2):(5-6), preferably 1:(1.3-1.7):(5.2-5.5).

[0064] In an optional embodiment, the mass of the catalyst is 1% to 2% of the mass of the polyisocyanate, preferably 1%.

[0065] In an optional embodiment, the polyol includes at least one of polyester polyol, polyether polyol, and a mixed polymer polyol of polyether and polyester. Preferably, the polyol includes at least one of polyethylene glycol, polyoxypropylene glycol, polytetramethylene glycol, polybutylene succinate, and polyhexane adipate.

[0066] In an optional embodiment, the number average molecular weight of the polyol is 1000 to 5000 g / mol, preferably 1200 to 2400 g / mol.

[0067] In an optional embodiment, the polyisocyanate includes at least one of toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and dicyclohexylmethane diisocyanate (HMDI); preferably, the polyisocyanate includes isophorone diisocyanate (IPDI) and toluene diisocyanate (TDI).

[0068] In an alternative embodiment, the catalyst is stannous octoate or dibutyltin dilaurate.

[0069] In an alternative embodiment, the hydrophilic chain extender includes at least one of 2,2 - dimethylolbutyric acid, dimethylolpropionic acid, sodium 2 - aminoethanesulfonate, sodium 3 - aminobenzenesulfonate, 3 - diaminopropionic acid, 4 - diaminobutyric acid, N - methyldiethanolamine, diethanolamine, and triethanolamine; preferably at least one of N - methyldiethanolamine, diethanolamine, and triethanolamine.

[0070] In an alternative embodiment, the neutralizing agent is at least one of triethylamine, hydrochloric acid, acetic acid, glycolic acid, and methacrylic acid.

[0071] In an alternative embodiment, the curing agent includes at least one of ethylenediamine, hexamethylenediamine, phenylenediamine, diethylenetriamine, and m - phenylenediamine; preferably ethylenediamine.

[0072] In an alternative embodiment, the dispersant includes at least one of Tween, alkylphenol polyoxyethylene ether, benzylphenol polyoxyethylene ether, phenethylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, alkyl sulfates, alkyl sulfonates, alkyl naphthalene sulfonates, or alkyl benzene sulfonates.

[0073] In some embodiments of the present invention, in the sea - island superfine fiber leather precursor in step four, the resin accounts for 40% - 70% of the weight of the partially - degreased base fabric based on the dry weight of the resin slurry.

[0074] In some embodiments of the present invention, the degreasing treatment liquid is an alkali solution, which depends on the type of the first sea component. In an alternative embodiment, the temperature of the degreasing treatment liquid is 50 - 90 °C, and the degreasing treatment methods include, but are not limited to, soaking, stirring, ultrasonic treatment, roll pressing, etc.

[0075] Example 1

[0076] A method for preparing a soft artificial leather, comprising the following steps:

[0077] Step 1: Prepare sea - island type ultrafine fibers

[0078] Prepare the first sea - island type ultrafine fibers and the second sea - island type ultrafine fibers respectively according to the following process: Add the island component and the sea - component resin to the feeding barrel of a screw extruder for heating and melting respectively. The two melts are transported through the melt pipeline to the spinning box body, accurately metered by metering pumps respectively, and then injected into the sea - island type composite component in the spinning box body. They are evenly distributed through the distribution pipe in the component, and finally the two melts converge and are extruded at the entrance of the spinneret holes; Cool, oil, stretch, shape, and wind up the extruded fibers to obtain sea - island type ultrafine fibers.

[0079] The first sea component of the first sea-island type superfine fiber is a water-soluble copolyester (COPET), the first island component is polyamide (PA6), the mass ratio of the sea component to the island component is 40:60, and the number of islands is 37;

[0080] The second sea component of the second sea-island type superfine fiber is polyvinyl alcohol, the second island component is polyamide (PA6), the mass ratio of the sea component to the island component is 50:50, and the number of islands is 37;

[0081] The screw temperatures of the first island component and the second island component are as follows: Zone 1: 230 °C → Zone 2: 250 °C → Zone 3: 270 °C → Zone 4: 290 °C → Zone 5: 280 °C;

[0082] The screw temperatures of the first sea component are as follows: Zone 1: 180 °C → Zone 2: 220 °C → Zone 3: 240 °C → Zone 4: 260 °C → Zone 5: 240 °C;

[0083] The screw temperatures of the second sea component are as follows: Zone 1: 120 °C → Zone 2: 150 °C → Zone 3: 170 °C → Zone 4: 190 °C → Zone 5: 170 °C;

[0084] Side blowing is used for cooling, the wind speed is 0.6 m / s, and the wind temperature is 25 °C; the oil application amount is 0.5 wt% of the fiber; the draw ratio is 2.5, the setting temperature is 160 °C, and the winding speed is 2500 m / min.

[0085] Step 2: Prepare the base fabric

[0086] The first sea-island type superfine fiber and the second sea-island type superfine fiber are mixed in a mass ratio of 70:30, and after opening, carding, and spinning, a composite fiber yarn is obtained. Using the composite fiber yarn as the warp and weft, plain weaving is carried out to form the base fabric.

[0087] Step 3: Prepare the partially deweighted base fabric

[0088] The obtained base fabric is put into the treating agent solution for ultrasonic treatment for 60 min, the bath ratio is 1:30, then taken out and soaked and washed with normal temperature water for 5 min and the washing step is repeated 3 times to obtain the partially deweighted base fabric, and air-dried to control the water content of the partially deweighted base fabric to be less than 20%.

[0089] The treating agent solution is an aqueous alcohol solution of benzenesulfonamide with a benzenesulfonamide concentration of 1 g / L.

[0090] The alcohol is ethanol, and the volume ratio with water is 20%:1.

[0091] Step 4: Prepare the precursor of sea-island superfine leather

[0092] Use a roll coater to scrape and coat the resin slurry on the surface of the partially deresinated base fabric. The resin slurry comprises the following components: 30 parts of polyurethane prepolymer, 12 parts of soy protein isolate, 0.5 part of silicone defoamer, 0.4 part of ultraviolet absorber UV-326, 5 g of ethylenediamine, and 210 parts of water.

[0093] The preparation method of the resin slurry is as follows:

[0094] (1) Under nitrogen protection, mix 60 g of polytetrahydrofuran ether glycol (number average molecular weight: 2000 g / mol), 34.5 g of isophorone diisocyanate, 0.35 g of dibutyltin dilaurate, and 4.65 g of N-methyldiethanolamine, and heat up to 80 °C for stirring reaction. React until the NCO content reaches stability, and then add hydrochloric acid for neutralization to obtain the polyurethane prepolymer.

[0095] (2) Add soy protein isolate to the polyurethane prepolymer. After stirring evenly, add deionized water, and finally add ethylenediamine, and perform shear dispersion for 1 h to obtain the soy protein modified polyurethane emulsion.

[0096] (3) Add the silicone defoamer and the ultraviolet absorber to the soy protein modified polyurethane emulsion. After stirring and mixing at 800 rpm, add deionized water to control the solid content to 18% to obtain the resin slurry.

[0097] In the obtained sea-island superfine fiber leather precursor, the resin accounts for 57% of the weight of the partially deresinated base fabric based on the dry weight of the slurry.

[0098] The temperature for heating and drying is 120 °C.

[0099] Step Five: Prepare the superfine fiber synthetic leather base fabric

[0100] Place the sea-island superfine fiber leather precursor in an aqueous sodium hydroxide solution at a temperature of 50 °C and a concentration of 3% for deresination and fiber opening for 45 min, with a bath ratio of 1:20. Then wash it with water until neutral and dry it at 130 °C to obtain the superfine fiber synthetic leather base fabric.

[0101] Step Six: Prepare artificial leather

[0102] After dry laminating, surface treatment, polishing, embossing, water kneading, and ironing of the superfine fiber synthetic leather base fabric, soft artificial leather is obtained.

[0103] Example 2

[0104] A method for preparing soft artificial leather, comprising the following steps:

[0105] Step One: Prepare sea-island type superfine fibers

[0106] The difference from Example 1 is that: the first sea component of the first sea-island type ultrafine fiber is water-soluble copolyester (COPET), the first island component is high-density polyethylene, the mass ratio of the sea component to the island component is 30:70, and the number of islands is 51;

[0107] The second sea component of the second sea-island type ultrafine fiber is polyvinyl alcohol, the second island component is polyamide (PA56), the mass ratio of the sea component to the island component is 70:30, and the number of islands is 37;

[0108] The screw temperatures of the first island component are as follows: Zone 1: 200 °C → Zone 2: 220 °C → Zone 3: 240 °C → Zone 4: 265 °C → Zone 5: 260 °C;

[0109] The screw temperatures of the second island component are as follows: Zone 1: 230 °C → Zone 2: 250 °C → Zone 3: 270 °C → Zone 4: 290 °C → Zone 5: 285 °C;

[0110] The screw temperatures of the first sea component are as follows: Zone 1: 180 °C → Zone 2: 220 °C → Zone 3: 240 °C → Zone 4: 260 °C → Zone 5: 240 °C;

[0111] The screw temperatures of the second sea component are as follows: Zone 1: 120 °C → Zone 2: 150 °C → Zone 3: 170 °C → Zone 4: 190 °C → Zone 5: 170 °C;

[0112] Step 2: Prepare the base fabric

[0113] Same as Example 1.

[0114] Step 3: Prepare the partially deweighted base fabric

[0115] The difference from Example 1 is that:

[0116] The treatment agent solution is an aqueous alcohol solution of N-methylpyrrolidone with a concentration of 1 g / L of N-methylpyrrolidone.

[0117] The alcohol is ethylene glycol, and the volume ratio to water is 10%:1.

[0118] Step 4: Prepare the precursor of sea-island ultra-fine leather

[0119] Use a roll coater to scrape and coat the resin slurry on the surface of the partially deweighted base fabric. The resin slurry includes the following components: 20 parts of polyurethane prepolymer, 5 parts of soy protein isolate, 0.1 part of silicone defoamer, 0.1 part of ultraviolet absorber UV-326, 3 parts of hexamethylenediamine, 0.2 part of Tween-80, and 70 parts of water.

[0120] The preparation method of the resin slurry is as follows:

[0121] (1) Under nitrogen protection, 30 g of poly(hexylene adipate) (number-average molecular weight of 3000 g / mol), 18 g of polyethylene glycol (number-average molecular weight of 1200 g / mol), 24 g of toluene diisocyanate, 0.24 g of stannous octoate, and 3.5 g of diethanolamine were mixed and heated to 80 °C with stirring for reaction. When the NCO content reached a stable state, acetic acid was added for neutralization to obtain a polyurethane prepolymer.

[0122] (2) A dispersant Tween-80 and soy protein isolate were added to the polyurethane prepolymer. After stirring evenly, deionized water was added, and finally hexamethylenediamine was added for shear dispersion for 1 h to obtain a soy protein-modified polyurethane emulsion.

[0123] (3) An organosilicon defoamer and an ultraviolet absorber were added to the soy protein-modified polyurethane emulsion. After stirring and mixing at 800 rpm, deionized water was added to control the solid content to 28% to obtain a resin slurry.

[0124] In the obtained sea-island ultra-fine fiber leather precursor, the resin accounted for 70% of the weight of the partially-deweighted base fabric based on the dry weight of the slurry.

[0125] The temperature for heating and drying was 120 °C.

[0126] Step Five: Preparation of ultra-fine fiber synthetic leather base fabric

[0127] The sea-island ultra-fine fiber leather precursor was placed in a sodium hydroxide aqueous solution at a temperature of 50 °C and a concentration of 3% for weight reduction and fiber opening for 45 min, with a bath ratio of 1:20. Then it was washed with water until neutral and dried at 130 °C to obtain an ultra-fine fiber synthetic leather base fabric.

[0128] Step Six: Preparation of artificial leather

[0129] The ultra-fine fiber synthetic leather base fabric was subjected to dry lamination, surface treatment, polishing, embossing, water kneading, and ironing to obtain a soft artificial leather.

[0130] Example 3

[0131] A method for preparing a soft artificial leather, comprising the following steps:

[0132] Step One: Preparation of sea-island type ultra-fine fibers

[0133] The difference from Example 1 is that the first sea component of the first sea-island type ultra-fine fiber is a water-soluble copolyester (COPET), the first island component is high-density polyethylene, the mass ratio of the sea component to the island component is 20:80, and the number of islands is 51;

[0134] The second sea component of the second sea-island type ultrafine fiber is polyvinylpyrrolidone, the second island component is high-density polyethylene, the mass ratio of the sea component to the island component is 80:20, and the number of islands is 37;

[0135] The screw temperatures of the first island component and the second island component are as follows: Zone 1: 200 °C → Zone 2: 220 °C → Zone 3: 240 °C → Zone 4: 265 °C → Zone 5: 260 °C;

[0136] The screw temperatures of the first sea component are as follows: Zone 1: 180 °C → Zone 2: 220 °C → Zone 3: 240 °C → Zone 4: 260 °C → Zone 5: 240 °C;

[0137] The screw temperatures of the second sea component are as follows: Zone 1: 150 °C → Zone 2: 170 °C → Zone 3: 190 °C → Zone 4: 220 °C → Zone 5: 210 °C;

[0138] Step 2: Prepare the base fabric

[0139] The same as in Example 1.

[0140] Step 3: Prepare the partially-deweighted base fabric

[0141] The difference from Example 1 is that:

[0142] The treatment agent solution is an aqueous alcohol solution of butyl salicylate with a concentration of 1 g / L of butyl salicylate.

[0143] The alcohol is glycerol, and the volume ratio to water is 30%:1.

[0144] Step 4: Prepare the precursor of sea-island ultrafine fiber leather.

[0145] Use a roll coater to scrape and coat the resin slurry on the surface of the partially-deweighted base fabric. The resin slurry includes the following components: 40 parts of polyurethane prepolymer, 20 parts of soy protein isolate, 0.8 part of silicone defoamer, 0.8 part of ultraviolet absorber UV-326, 8 parts of ethylenediamine, 0.6 part of fatty alcohol polyoxyethylene ether AEO-3, and 350 parts of water.

[0146] The preparation method of the resin slurry is as follows:

[0147] (1) Under nitrogen protection, mix 30 g of poly(hexamethylene adipate) (number average molecular weight of 4000 g / mol), 35 g of poly(propylene glycol) (number average molecular weight of 2000 g / mol), 34 g of dicyclohexylmethane diisocyanate, 0.34 g of stannous octoate, and 6.3 g of triethanolamine, and heat up to 80 °C for stirring reaction. React until the NCO content reaches stability, and then add hydrochloric acid for neutralization to obtain the polyurethane prepolymer.

[0148] (2) Add dispersant AEO-3 and soy protein isolate into the polyurethane prepolymer. After stirring evenly, add deionized water, and finally add ethylenediamine and shear and disperse for 1 h to obtain the soy protein-modified polyurethane emulsion.

[0149] (3) Add the silicone defoamer and ultraviolet absorber into the soy protein-modified polyurethane emulsion. After stirring and mixing at 800 rpm, add deionized water to control the solid content to be 15%, and then the resin slurry is obtained.

[0150] In the obtained sea-island ultra-fine fiber leather precursor, the resin accounts for 40% of the weight of the partially reduced base fabric based on the dry weight of the slurry.

[0151] The temperature of heating and drying is 120 °C.

[0152] Step Five: Prepare the ultra-fine fiber synthetic leather base fabric

[0153] Place the sea-island ultra-fine fiber leather precursor in an aqueous sodium hydroxide solution at 50 °C and a concentration of 3% for weight reduction and fiber opening for 45 min, with a bath ratio of 1:20. Then wash it to neutral and dry it at 130 °C to obtain the ultra-fine fiber synthetic leather base fabric.

[0154] Step Six: Prepare artificial leather

[0155] After the ultra-fine fiber synthetic leather base fabric undergoes dry laminating, surface treatment, polishing, embossing, water kneading, and ironing, soft artificial leather is obtained.

[0156] Example 4

[0157] The difference from Example 1 is that in Step Two: The first sea-island type ultra-fine fiber and the second sea-island type ultra-fine fiber are blended in a mass ratio of 90:10 to obtain a composite fiber yarn.

[0158] Example 5

[0159] The difference from Example 1 is that in Step Two: The first sea-island type ultra-fine fiber and the second sea-island type ultra-fine fiber are blended in a mass ratio of 50:50 to obtain a composite fiber yarn.

[0160] Example 6

[0161] The difference from Example 1 is that in Step Three, the treatment agent solution is an aqueous alcohol solution of benzenesulfonamide with a concentration of 0.2 g / L of benzenesulfonamide.

[0162] Example 7

[0163] The difference from Example 1 is that in Step Three, the treatment agent solution is an aqueous alcohol solution of benzenesulfonamide with a concentration of 2 g / L of benzenesulfonamide.

[0164] Comparative Example 1

[0165] The difference from Example 1 is that Step 3 is not carried out. That is, the base fabric obtained in Step 2 is directly subjected to resin compounding and curing to obtain the precursor of sea-island superfine fiber leather, and then weight reduction is carried out in Step 4.

[0166] Therefore, the components for weight reduction in Step 4 include the first sea component and the second sea component.

[0167] Comparative Example 2

[0168] The difference from Example 1 is that in Step 2, the second sea-island type ultra-fine fiber is not added, that is, the first sea-island type ultra-fine fiber is used as the warp and weft yarns to weave the base fabric.

[0169] Comparative Example 3

[0170] The difference from Example 1 is that the first sea component and the second sea component of the base fabric are both subjected to weight reduction in Step 3. Therefore, Step 5 is not carried out. The specific steps are as follows:

[0171] Step 1 and Step 2 are the same as those in Example 1;

[0172] Step 3: The obtained base fabric is put into a treating agent solution at 50 °C and ultrasonically treated for 60 min, the bath ratio is 1:30, and then taken out and soaked and washed with normal temperature water for 5 min and the washing step is repeated 5 times to obtain the weight-reduced base fabric, and the water content of the partially weight-reduced base fabric is controlled to be less than 20% by air drying.

[0173] The solvent of the treating agent solution is an aqueous solution of ethanol (the volume ratio of ethanol to water is 20%:1), and the components of the treating agent solution include: 1 g / L of benzenesulfonamide and 30 g / L of NaOH.

[0174] Step 4 and Step 6 are the same as those in Example 1.

[0175] Comparative Example 4

[0176] The difference from Example 1 is that in Step 3, the treating agent is not added, that is, an aqueous alcohol solution is used for the first weight reduction of the base fabric.

[0177] Comparative Example 5

[0178] The difference from Example 1 is that in Step 3, the treating agent benzenesulfonamide is not added, and in Step 5, the treating agent benzenesulfonamide is added, that is, an aqueous alcohol solution is used for the first weight reduction of the base fabric, and the treating agent benzenesulfonamide is added to the weight reduction treatment liquid in Step 5 for the second weight reduction.

[0179] The solvent of the weight reduction treatment liquid in Step 5 is water, and the components of the weight reduction treatment liquid include: 1 g / L of benzenesulfonamide and 30 g / L of NaOH.

[0180] The artificial leathers prepared in the examples and comparative examples are subjected to performance tests.

[0181] Test Example 1

[0182] Evaluate the softness of artificial leather. According to the standard NF G52-033-2012 "Leather - Physical and mechanical tests - Determination of softness", test the softness of the test specimen, and a shrinkage ring diameter of 35 mm is selected for the test.

[0183] Test Example 2

[0184] Test the flexural rigidity of artificial leather. According to the standard GB / T 18318.1-2009 "Textiles - Determination of bending properties - Part 1: Inclined plane method", test the flexural rigidity of the test specimen.

[0185] Test Example 3

[0186] Test the mechanical properties of artificial leather. According to the standard GB / T24218.3-2010 "Textiles - Test methods for nonwovens - Part 3: Determination of breaking strength and elongation at break (strip method)", test the breaking strength and elongation at break of the test specimen, with a gauge length of 20 cm and a tensile speed of 100 mm / min.

[0187] Test Example 4

[0188] Test the tensile recovery speed of artificial leather. Specifically, measure the following two indicators: ① The recovery rate 1 s after the warp elongation reaches 10%; ② The recovery rate 1 s after the weft elongation reaches 30%; The measurement methods for the above two indicators are as follows: Prepare a cloth sample, place it in the tensile machine fixture from the warp and weft directions respectively, with a gauge length of 20 cm and a tensile speed of 100 mm / min. After the elongation rate of the warp tensile reaches 10% or the elongation rate of the weft tensile reaches 30%, release one side of the fixture, record the process with a camera, and analyze and calculate the elongation rate of the cloth sample relative to that before stretching 1 s after release.

[0189] The test results of Test Examples 1 to 4 are listed in Table 1.

[0190] Table 1

[0191]

[0192] As can be seen from the results in Table 1, in Comparative Example 1, since the base fabric was not partially fibrillated with a treatment agent solution before resin compounding, the artificial leather obtained had lower softness and strength compared to Example 1. Comparing Example 1, Examples 4 and 5, and Comparative Example 2, it can be seen that the ratio of the first sea-island ultrafine fiber to the second sea-island ultrafine fiber in the base fabric has an impact on the softness and mechanical strength of the artificial leather. Specifically, the higher the proportion of the second sea-island ultrafine fiber, the lower the softness of the artificial leather. The reason is that: the higher the proportion of the second sea-island ultrafine fiber leads to a higher degree of partial fibrillation, and the closer the binding between the resin slurry and the fiber, resulting in limited mobility of the resin layer, thus reducing the softness of the artificial leather and making the hand feel stiff. The higher the proportion of the second sea-island ultrafine fiber, the breaking strength of the artificial leather shows a trend of increasing first and then decreasing. The reason is that the higher the proportion of the second sea-island ultrafine fiber, the higher the degree of partial fibrillation, and the closer the binding between the resin slurry and the fiber, so the strength of the artificial leather is higher and the elongation at break is lower; but when the proportion of the second sea-island ultrafine fiber is too high, the content of the island component is lower, and the fiber content in the artificial leather is less, resulting in a decrease in the strength of the artificial leather and an increase in the elongation at break. The higher the proportion of the second sea-island ultrafine fiber, the elongation at break of the artificial leather increases first and then decreases. The reason is that: the higher the proportion of the second sea-island ultrafine fiber, the higher the overall fibrillation degree of the artificial leather and the lower the island content, resulting in enhanced mobility of the leather and an increase in the elongation at break. However, when the proportion of the second sea-island ultrafine fiber is too high, the binding tightness between the resin slurry and the fiber is too high, which instead limits the mobility of the leather, resulting in a decrease in the elongation at break.

[0193] Comparing Example 1 and Comparative Example 3, after the base fabric was completely fibrillated and then resin-compounded, the binding tightness between the resin slurry and the fiber was too high, and the mobility of the resin layer was limited, thus reducing the softness of the artificial leather and making the hand feel stiff. At the same time, the obtained artificial leather had a higher breaking strength and a lower elongation at break.

[0194] Comparing Example 1, Examples 6 and 7, and Comparative Example 4, it can be seen that the higher the concentration of the treatment agent in the treatment agent solution, the higher the softness of the artificial leather but the lower the breaking strength and the higher the elongation at break. The reason is that the treatment agent has a plasticizing effect on the island component, which can increase the mobility of the molecular chains of the island component, thereby improving the softness of the artificial leather, reducing its breaking strength, and increasing its elongation at break.

[0195] Comparing Example 1 and Comparative Example 5, when the treatment agent was added during fibrillation after resin compounding, the improvement effect on the softness of the artificial leather was better, but the mechanical strength of the artificial leather was reduced. The reason is that the treatment agent also has a certain degree of softening effect on the resin layer, resulting in a decrease in the mechanical strength of the artificial leather.

[0196] The present invention evaluates the elasticity of artificial leather from two dimensions. On the one hand, it lies in the elongation of artificial leather, which reflects the deformation ability of the material; on the other hand, it lies in the rebound speed of artificial leather after stretching, which reflects the ability of the material to return to its original state after being subjected to force. The present invention evaluates the rebound speed of artificial leather by the recovery rate of 1s after the warp elongation is 10% and the recovery rate of 1s after the weft elongation is 30%. Analysis of the data in Table 1 shows that the higher the proportion of the second sea island microfiber, the rebound speed of artificial leather shows a trend of first increasing and then decreasing. The reason is that the higher the proportion of the second sea island microfiber, the higher the degree of partial fiber opening, the higher the degree of bonding between the resin slurry and the fiber, the worse the activity of the artificial leather structure, and the rigid rebound, so the rebound speed is faster; when the proportion of the second sea island microfiber is too high, the island component content decreases, the activity of the artificial leather structure increases, the rigidity of the material is lower, and the rebound speed slows down. The higher the concentration of the treating agent in the treating agent solution, the slower the rebound speed of the artificial leather, because as the concentration of the treating agent increases, the rigidity of the artificial leather decreases, and thus the rebound speed becomes slower.

[0197] Test Example 5

[0198] The air permeability of artificial leather was tested according to the standard GB / T 24218.15-2018 "Test methods for textile nonwovens Part 15: Determination of air permeability". The experimental pressure difference was 100Pa and the test area was 20cm 2 .

[0199] Test Example 6

[0200] The moisture permeability of artificial leather was tested according to the standard FZ / T 98020-2019 "Fabric Moisture Permeability Tester". The test environment temperature was (38±2)℃ and the humidity was (50±2)%. The moisture permeability was calculated as follows: In the formula, m 1 、m 0 are the masses of the sample before and after the test, in g; A is the effective test area of ​​the sample, in m 2 ; T is the test time, in hours.

[0201] The present invention tests the air permeability and moisture permeability of Example 1 and Comparative Examples 1 to 5, and the results are listed in Table 2.

[0202] Table 2

[0203] sample <![CDATA[Air permeability, L·(m 2 ·s) -1 > <![CDATA[Water vapor transmission rate, g·(m 2 ·h) -1 <!-- 12 -->]]> Example 1 27 202 Comparative Example 1 28 213 Comparative Example 2 26 206 Comparative Example 3 20 172 Comparative Example 4 27 211 Comparative Example 5 25 197

[0204] It can be seen from the data in Table 2 that the air permeability and moisture permeability of Comparative Example 1 are greater than those of Example 1. The reason is that in Example 1, the resin and the fiber are more tightly combined and the bonding area is larger. Therefore, the obtained artificial leather has better mechanical properties but sacrifices some air permeability and moisture permeability. The base fabric of Comparative Example 2 does not contain the second sea-island ultrafine fiber. Since the content of the island component in the finally obtained artificial leather is higher than that of Example 1 and Comparative Example 1, the air permeability and moisture permeability are slightly lower. In Comparative Example 3, all the sea components are reduced in weight before resin compounding, so the air permeability and moisture permeability are the worst. In Comparative Example 4, the treatment agent is not added during the first weight reduction, but it has little effect on the air permeability and moisture permeability of the artificial leather. In Comparative Example 5, the treatment agent is added only during the second weight reduction, resulting in a decrease in the air permeability and moisture permeability of the artificial leather.

[0205] The above content is a further detailed description of the present invention in combination with specific preferred technical solutions. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing soft artificial leather, characterized in that: The following steps are involved: Step 1: using a composite spinning method to prepare a first island-in-sea type ultrafine fiber and a second island-in-sea type ultrafine fiber, wherein the first island-in-sea type ultrafine fiber comprises a first island component and a first sea component; and the second island-in-sea type ultrafine fiber comprises a second island component and a second sea component; Step 2: blending the first sea-island type ultrafine fiber and the second sea-island type ultrafine fiber to obtain a composite fiber yarn, and then weaving the blended fiber yarn to form a base fabric; Step 3: placing the base fabric in a treatment agent solution for a first reduction, the purpose of which is to remove the second sea component, thereby obtaining a partially reduced base fabric; Step 4: compounding the partially reduced base fabric with resin by a doctor blade method, and obtaining a sea island microfiber leather precursor after heating and curing; Step 5: placing the sea island microfiber leather precursor in a weight reduction treatment liquid for a second weight reduction, and then washing and drying to obtain a microfiber synthetic leather base fabric; Step 6: The ultrafine fiber synthetic leather base fabric is processed by at least one post-finishing process including dry veneer, surface treatment, polishing, embossing, water kneading, and ironing to obtain soft artificial leather; The second sea component is a water-soluble spinnable polymer or a composition containing a water-soluble spinnable polymer; the second sea component includes at least one of polyvinyl pyrrolidone or a composition thereof, polyvinyl alcohol or a composition thereof; The first sea component is water-soluble polyester COPET; The treatment agent solution is an alcohol aqueous solution of the treatment agent, and the treatment agent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, phenol, methyl salicylate, and benzenesulfonamide; The weight reduction treatment liquid is an alkali solution.

2. The preparation method according to claim 1, characterized in that: The step 1 has at least one of the following characteristics: Feature 1: The first island component and the second island component are independently selected from one of the following: polyamide or its derivatives, polyester or its derivatives, polystyrene, polyethylene or polypropylene; Feature 2: The first sea component includes at least one of polyester or its derivatives, polyurethane or its derivatives. Feature 3: The mass ratio of the first sea component to the first island component is (20:80) to (80:20); Feature 4: The mass ratio of the second sea component to the second island component is (20:80) to (80:20); Feature 5: The number of islands of the first sea-island type ultrafine fibers and the number of islands of the second sea-island type ultrafine fibers are independently 16 to 500.

3. The preparation method according to claim 1, characterized in that: In the step 2, the mass ratio of the blended first sea-island type ultrafine fibers and the second sea-island type ultrafine fibers is (90:10) to (50:50).

4. The preparation method according to any one of claim 1, characterized in that: The concentration of the treating agent in the treating agent solution is 0.2-2 g / L.

5. The preparation method according to claim 1, characterized in that: The first reduction refers to ultrasonic treatment at room temperature for 30 to 60 minutes.

6. The preparation method according to claim 1, characterized in that: The resin slurry in step 4 has at least one of the following characteristics: Feature 6: The solid content of the resin slurry is 15% to 28%; Feature 7: The resin slurry, calculated by mass, includes the following components: 20-40 parts of polyurethane prepolymer, 5-20 parts of soy protein isolate, 0.1-0.8 parts of defoaming agent, 0.1-0.8 parts of ultraviolet absorber, 3-8g of curing agent, 0-0.6 parts of dispersant, and 70-350 parts of water.

7. The preparation method according to claim 1, characterized in that: In step 4, the resin in the island microfiber leather precursor accounts for 40% to 70% of the weight of the partially reduced base fabric based on the dry weight of the resin slurry.

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