Water-based polyurethane resin capable of absorbing stripes as well as preparation method and application of water-based polyurethane resin

Abstract

The invention provides waterborne polyurethane resin capable of absorbing stripes as well as a preparation method and application of the waterborne polyurethane resin. The waterborne polyurethane resin capable of absorbing stripes is prepared from the following raw materials in specific contents: polyester polyol, hydroxyl-terminated ethylene oxide-propylene oxide copolyether, an alcohol chain extender, isocyanate, a post chain extender and a solvent. Specific polyester polyol is selected to be matched with hydroxyl-terminated ethylene oxide-propylene oxide copolyether, and the use amount of each component is controlled in a specific range, so that the prepared waterborne polyurethane resin capable of absorbing the lines has excellent softness, hydrolysis resistance and line-absorbing setting property at normal temperature, is suitable for being used as a synthetic leather foaming layer material, and can be used as a synthetic leather foaming layer material. The grains can be formed on the surface of the synthetic leather through a grain suction and embossing method, and the formed grains are high in definition and have high-temperature non-resilience.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane, and in particular to a waterborne polyurethane resin capable of absorbing grains, and a preparation method and application thereof. Background Art

[0002] At present, synthetic leather has good comprehensive performance and is widely used in the shoe, clothing, luggage and other industries. The raw materials of traditional synthetic leather technology are all solvent-based polyurethane. During the production process, N,N-dimethylformamide (DMF) volatilizes, and some toxic chemical components may remain, which causes great harm to the physical and mental health of producers and users. Water-based polyurethane uses natural pollution-free water as a solvent. There is no toxic gas release during the production and use process, and it is harmless to the human body. It gradually replaces traditional solvent-based polyurethane and becomes a new water-based green and environmentally friendly synthetic innovation technology.

[0003] At present, synthetic leather factories mainly use release paper transfer veneer and suction embossing methods to form textures on the surface of synthetic leather. Compared with embossing, the texture of synthetic leather made by release paper transfer veneer is not clear enough and the three-dimensional sense is not strong. In addition, the price of release paper is expensive and the number of uses is limited, which greatly increases the production cost of synthetic leather. Therefore, the method of using suction embossing to form textures on the surface of synthetic leather is becoming more and more popular in the market.

[0004] For example, CN114379175A and CN111016310A both disclose the use of two-component solvent-free resin as the foaming layer and adhesive layer of synthetic leather to achieve the embossing effect, but the two-component solvent-free resins used in these two inventions have different characteristics. Another example is CN118085216A discloses a high modulus, high filling and high color development polyurethane wet-process absorbing grain resin, but it does not belong to the application scope of water-based polyurethane. Another example is CN117166260A discloses the use of water-based polyurethane as the surface layer, foaming layer and adhesive layer, and the preparation of water-based polyurethane foam dry-process semi-finished products by release paper transfer film method, and then the required pattern is obtained through printing, absorbing grain and other processes, and finally the surface printing, polishing and other processes are used to obtain high-physical property water-based polyurethane synthetic leather, but the invention does not involve the synthesis method of the water-based polyurethane used in the foaming layer, or where the water-based polyurethane comes from, but only describes the preparation method of synthetic leather.

[0005] In addition, most of the existing embossed products on the market are made of solvent-based polyurethane or solvent-free polyurethane as the foaming layer, and there are no commercial products that use water-based polyurethane as the synthetic leather foaming layer for leather-like embossing molding; among them, solvent-based polyurethane is too poor in environmental protection, and although solvent-free polyurethane is environmentally friendly, its application in soft synthetic leather is limited. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a water-based polyurethane resin with absorbent texture, and a preparation method and application thereof. The water-based polyurethane resin with absorbent texture has absorbent texture embossing properties, and the texture formed does not recover at high temperature and is soft and elastic, and is suitable for preparing a soft synthetic leather foaming layer.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a waterborne polyurethane resin with absorbable lines. Taking the total mass of the raw materials of the waterborne polyurethane resin with absorbable lines as 100%, the raw materials include the following components in the following amounts:

[0009]

[0010]

[0011] The polyester polyol includes any one of poly(octyl pentyl adipate), poly(octyl pentyl adipate cyclohexanedimethanol), hexylene glycol phthalate or dimer acid polyester or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of poly(octyl pentyl adipate) and poly(octyl pentyl adipate cyclohexanedimethanol), a combination of poly(octyl pentyl adipate) and dimer acid polyester, a combination of hexylene glycol phthalate and dimer acid polyester, and the like.

[0012] The present invention limits the raw materials of the absorbent waterborne polyurethane resin to include a specific content of polyester polyol, terminal hydroxyl ethylene oxide-propylene oxide copolyether, alcohol chain extender, isocyanate, post-chain extender and solvent, and limits the polyester polyol to include any one or a combination of at least two of poly(octyl pentyl adipate), poly(cyclohexanedimethanol adipate), hexanediol phthalate or dimer acid polyester, and through the reasonable combination of the above components, especially the selection of a specific polyester polyol and the terminal hydroxyl ethylene oxide-propylene oxide copolyether to prepare the absorbent waterborne polyurethane resin. The obtained waterborne polyurethane resin with absorbent texture has excellent softness, hydrolysis resistance and absorbent texture setting property at room temperature. As a foaming layer material for synthetic leather, the surface of the synthetic leather can be patterned by the absorbent texture embossing method, and the formed texture has high clarity and high-temperature non-recovery. Moreover, by adding the terminal hydroxyl ethylene oxide-propylene oxide copolyether, the obtained waterborne polyurethane resin can also have good hydrolysis resistance. Furthermore, by adding a post-chain extender, the heat resistance of the waterborne polyurethane resin can be effectively guaranteed to be very excellent.

[0013] In addition, in the present invention, the selection of the above-mentioned polyester polyol with relatively weak crystallinity and relatively good hydrolysis resistance can make the soft synthetic leather foam layer further prepared by the obtained waterborne polyurethane resin have better softness and hydrolysis resistance; if a polyester polyol with relatively good crystallinity (such as polybutylene adipate) is selected, the performance of the prepared waterborne polyurethane will be poor, and the synthetic leather foam layer will feel harder after being further made.

[0014] In the present invention, the amount of the polyester polyol can be 19%, 20%, 21%, 22%, 23% or 24%, etc.

[0015] The amount of the terminal hydroxyl ethylene oxide-propylene oxide copolyether can be 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3% or 3.4%, etc.

[0016] The amount of the alcohol chain extender can be 1.2%, 1.3%, 1.4%, 1.5%, 1.6% or 1.7%, etc.

[0017] The amount of the isocyanate can be 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6%, 6.1% or 6.2%, etc.

[0018] The amount of the post-chain extender can be 0.5%, 0.6%, 0.7%, 0.8% or 0.9%, etc.

[0019] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0020] Preferably, the R value of the raw material of the absorbent waterborne polyurethane resin is 1.16 to 1.22, for example, 1.16, 1.17, 1.18, 1.19, 1.2, 1.21 or 1.22.

[0021] In the present invention, the "R value" refers to the ratio of the molar amount of NCO functional groups in the raw material of the absorbent waterborne polyurethane resin to the molar amount of OH functional groups in the system.

[0022] Preferably, the number average molecular weight of the polyester polyol is 1000-3000 g / mol, for example, 1000 g / mol, 1200 g / mol, 1400 g / mol, 1600 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2400 g / mol, 2600 g / mol, 2800 g / mol or 3000 g / mol.

[0023] Preferably, the number average molecular weight of the terminal hydroxyl ethylene oxide-propylene oxide copolyether is 2000-4000 g / mol, for example, 2000 g / mol, 2200 g / mol, 2400 g / mol, 2600 g / mol, 2800 g / mol, 3000 g / mol, 3200 g / mol, 3400 g / mol, 3600 g / mol, 3800 g / mol or 4000 g / mol, etc.

[0024] Preferably, the mass ratio of ethylene oxide to propylene oxide in the hydroxy-terminated ethylene oxide-propylene oxide copolyether is (2-6):1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1 or 6:1.

[0025] Preferably, the alcohol chain extender includes any one of 1,4-butanediol, neopentyl glycol or cyclohexanedimethanol or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of 1,4-butanediol and neopentyl glycol, a combination of neopentyl glycol and cyclohexanedimethanol, and the like.

[0026] Preferably, the isocyanate includes any one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate or diphenylmethane-4,4′-diisocyanate, or a combination of at least two thereof, wherein typical but non-limiting combinations include: a combination of isophorone diisocyanate and dicyclohexylmethane diisocyanate, a combination of dicyclohexylmethane diisocyanate and toluene diisocyanate, a combination of dicyclohexylmethane diisocyanate, toluene diisocyanate and diphenylmethane-4,4′-diisocyanate, a combination of isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate and diphenylmethane-4,4′-diisocyanate, and the like.

[0027] Preferably, the post-chain extender comprises polyetheramine, for example, polyetheramine D230 and / or polyetheramine D400.

[0028] In the present invention, polyetheramine is introduced by post-chain extension, which can ensure the heat resistance of the obtained waterborne polyurethane resin and reduce urea bonds, thereby ensuring that the obtained waterborne polyurethane resin also has excellent wrinkle absorption and shaping properties.

[0029] Preferably, the solvent comprises water.

[0030] Preferably, the raw material of the absorbable waterborne polyurethane resin further includes a catalyst.

[0031] Preferably, the content of the catalyst in the raw material of the absorbent waterborne polyurethane resin is 0.01-0.04%, for example, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035% or 0.04%.

[0032] Preferably, the catalyst comprises any one of dibutyltin dilaurate, bismuth isooctanoate or bismuth octanoate or a combination of at least two thereof.

[0033] Preferably, the raw material of the absorbent waterborne polyurethane resin further includes a diluent.

[0034] Preferably, the content of the diluent in the raw material of the absorbent waterborne polyurethane resin is 32-36%, for example, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, 35%, 35.5% or 36%.

[0035] Preferably, the diluent comprises acetone.

[0036] In a second aspect, the present invention provides a method for preparing the waterborne polyurethane resin with absorbable lines as described in the first aspect, the preparation method comprising: mixing a polyester polyol, a terminal hydroxyl ethylene oxide-propylene oxide copolyether, an isocyanate and an optional catalyst, performing a first heat preservation reaction, adding an alcohol chain extender, performing a second heat preservation reaction, and then performing a first cooling, adding a solvent, stirring until completely emulsified, and finally adding a post-chain extender, performing a third heat preservation reaction, and obtaining the waterborne polyurethane resin with absorbable lines.

[0037] Preferably, a pretreatment step is further included before the mixing.

[0038] Preferably, the pretreatment comprises dehydrating the polyester polyol and the terminal hydroxyl ethylene oxide-propylene oxide copolyether respectively.

[0039] Preferably, the dehydration treatment method includes dehydration by reduced pressure distillation.

[0040] Preferably, the temperature of the reduced pressure distillation dehydration is 110-120°C, for example, 110°C, 112°C, 114°C, 116°C, 118°C or 120°C.

[0041] Preferably, the time for dehydration by reduced pressure distillation is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0042] Preferably, the pressure of the reduced pressure distillation dehydration is -0.1 to -0.09 MPa, for example, -0.1 MPa, -0.098 MPa, -0.096 MPa, -0.094 MPa, -0.092 MPa or -0.09 MPa.

[0043] Preferably, the mixing temperature is 60-65°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C or 65°C.

[0044] Preferably, the temperature of the first insulation reaction is 80-100°C, for example, 80°C, 85°C, 90°C, 95°C or 100°C.

[0045] Preferably, the first insulation reaction time is 2 to 3 hours, for example, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours.

[0046] Preferably, the temperature of the second insulation reaction is 75-90°C, for example, 75°C, 77°C, 79°C, 81°C, 83°C, 85°C, 87°C, 89°C or 90°C.

[0047] Preferably, the second insulation reaction time is 1 to 3 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0048] Preferably, the temperature of the system after the first cooling is 60-65°C, for example, 60°C, 61°C, 62°C, 63°C, 64°C or 65°C.

[0049] Preferably, after the first cooling, a step of adding a diluent for a second cooling is also included.

[0050] Preferably, the adding method is dropwise addition.

[0051] Preferably, the dropping rate is 10 to 50 mL / min, for example, 10 mL / min, 15 mL / min, 20 mL / min, 25 mL / min, 30 mL / min, 35 mL / min, 40 mL / min, 45 mL / min or 50 mL / min, etc.

[0052] Preferably, the temperature of the system after the second cooling is 20-30°C, for example, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C.

[0053] Preferably, the stirring speed is 1500-2500 rpm, for example, 1500 rpm, 1700 rpm, 1900 rpm, 2100 rpm, 2300 rpm or 2500 rpm.

[0054] Preferably, the temperature of the third insulation reaction is 40-60°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C.

[0055] Preferably, the third insulation reaction time is 20 to 50 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min or 50 min.

[0056] Preferably, the third insulation reaction further includes a post-treatment step.

[0057] Preferably, the post-treatment method comprises distillation under reduced pressure.

[0058] Preferably, the pressure of the reduced pressure distillation is -0.1 to -0.09 MPa, for example, -0.1 MPa, -0.098 MPa, -0.096 MPa, -0.094 MPa, -0.092 MPa or -0.09 MPa.

[0059] Preferably, the mixing, the first insulation reaction, the second insulation reaction, the first cooling and the third insulation reaction are all carried out in a protective gas atmosphere.

[0060] Preferably, the protective gas comprises nitrogen.

[0061] Preferably, the method for preparing the absorbable waterborne polyurethane comprises the following steps:

[0062] (1) respectively subjecting polyester polyol and terminal hydroxyl ethylene oxide-propylene oxide copolyether to dehydration by vacuum distillation at 110 to 120° C. and -0.1 to -0.09 MPa for 1 to 3 hours;

[0063] (2) In a protective gas atmosphere, at 60-65° C., the polyester polyol dehydrated by vacuum distillation, the terminal hydroxyl ethylene oxide-propylene oxide copolyether dehydrated by vacuum distillation, the isocyanate and the catalyst are mixed, and the first heat preservation reaction is carried out at 80-100° C. for 2-3 hours;

[0064] (3) in a protective gas atmosphere, adding an alcohol chain extender to the reaction system obtained in step (2), carrying out a second heat preservation reaction at 75 to 90° C. for 1 to 3 h, cooling to 60 to 65° C. for the first time, then dropping a diluent therein at a rate of 10 to 50 mL / min, and cooling to 20 to 30° C. for the second time;

[0065] (4) In a protective gas atmosphere, a solvent is added to the reaction system obtained in step (3), and the mixture is stirred at a rotation speed of 1500 to 2500 rpm until it is completely emulsified, and then a post-chain extender is added, and a third heat preservation reaction is carried out at 40 to 60° C. for 20 to 50 minutes, and finally, a reduced pressure distillation is carried out at -0.1 to -0.09 MPa to obtain the absorbent waterborne polyurethane resin.

[0066] In a third aspect, the present invention provides an application of the absorbent waterborne polyurethane resin as described in the first aspect, wherein the application includes a foaming layer for preparing soft synthetic leather.

[0067] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] The raw materials of the waterborne polyurethane resin with absorbable grain provided by the present invention include polyester polyols, terminal hydroxyl ethylene oxide-propylene oxide copolyethers, alcohol chain extenders, isocyanates, post-chain extenders and solvents in specific contents. By selecting specific polyester polyols and matching terminal hydroxyl ethylene oxide-propylene oxide copolyethers, and controlling the amounts of the above components within specific ranges, the prepared waterborne polyurethane resin with absorbable grain has excellent softness, hydrolysis resistance and absorbable grain setting properties at room temperature, is suitable for being used as a foaming layer material for synthetic leather, can form grains on the surface of synthetic leather by a method of absorbable grain embossing, and the formed grains have high clarity and high-temperature non-recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a physical picture of the synthetic leather made of the absorbent water-based polyurethane resin provided in Example 1. DETAILED DESCRIPTION

[0071] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0072] The parameters and sources of some components in the following examples and comparative examples are as follows:

[0073] (1) Poly(octylpentyl adipate): number average molecular weight is 2000 g / mol, purchased from Huafeng Synthetic Resin, brand number is PE56.

[0074] (2) Poly(cyclohexanedimethanol octylpentane adipate): number average molecular weight is 2000 g / mol, purchased from Huafeng Synthetic Resin, brand number is PE5856.

[0075] (3) Dimer acid polyester: number average molecular weight is 2000 g / mol, purchased from Baiyuan Chemical, brand name BY3020.

[0076] (4) Hexanediol phthalate: number average molecular weight is 2000 g / mol, purchased from Huafeng Synthetic Resin, brand number HF8356.

[0077] (5) Polybutylene adipate: number average molecular weight is 2000 g / mol, purchased from Huafeng Synthetic Resin, brand number PE3020.

[0078] (6) Poly(hexanediol adipate): number average molecular weight is 2000 g / mol, purchased from Huafeng Synthetic Resin, brand number PE5020.

[0079] (7) Polypropylene oxide ether polyol: number average molecular weight is 2000 g / mol, specifically Donol 2020P.

[0080] (8) Single-end hydroxylated ethylene oxide-propylene oxide random copolyether: number average molecular weight is 2000 g / mol, purchased from Changhua Chemical, brand name CHE-125.

[0081] (9) Polyetheramine D230: purchased from Sinopharm, CAS No.: 9046-10-0.

[0082] (10) Polyetheramine D400: purchased from Sinopharm, CAS number: 9046-10-0.

[0083] Example 1

[0084] This embodiment provides a water-based polyurethane resin with absorbent grain, the R value of the raw material of which is 1.18, and includes the following components in terms of mass percentage:

[0085] Poly(neopentyl adipate) 21.2%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 3.0%, isophorone diisocyanate 5.5%, 1,4-butanediol 1.2%, dibutyltin dilaurate 0.03%, acetone 32.1%, deionized water 36.37%, polyetheramine D230 0.6%;

[0086] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0087] (1) Add poly(neopentyl adipate) and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0088] (2) In a nitrogen atmosphere, at 60° C., poly (neopentyl adipate) dehydrated by vacuum distillation, single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, isophorone diisocyanate and dibutyltin dilaurate were mixed, and the first heat preservation reaction was carried out at 85° C. for 2 h;

[0089] (3) In a nitrogen atmosphere, 1,4-butanediol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 30 mL / min, and then cooled to 27° C. for a second time;

[0090] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D230 was added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 225 nm.

[0091] Example 2

[0092] This embodiment provides a water-based polyurethane resin with absorbent grain, the R value of the raw material of which is 1.21, and includes the following components in terms of mass percentage:

[0093] Dimer acid polyester 19.0%, polycyclohexanedimethanol octyl pentyl adipate 3.4%, dicyclohexylmethane diisocyanate 6.2%, neopentyl glycol 1.7%, bismuth isooctanoate 0.04%, acetone 36.0%, deionized water 32.76%, polyetheramine D230 0.9%;

[0094] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0095] (1) Add dimer acid polyester and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by reduced pressure distillation at 110° C. and −0.096 MPa for 1.5 h, and then cool to 60° C.;

[0096] (2) in a nitrogen atmosphere, at 60° C., the dimer acid polyester dehydrated by vacuum distillation, the single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, dicyclohexylmethane diisocyanate and bismuth isooctanoate were mixed, and the first heat preservation reaction was carried out at 85° C. for 2 h;

[0097] (3) In a nitrogen atmosphere, neopentyl glycol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 20 mL / min, and then cooled to 27° C. for a second time;

[0098] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D230 was added, and the mixture was kept warm for a third time at 45° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 195 nm.

[0099] Example 3

[0100] This embodiment provides a water-based polyurethane resin with absorbent grain, the R value of the raw material of which is 1.17, and includes the following components in terms of mass percentage:

[0101] Dimer acid polyester 10.2%, poly(cyclohexanedimethanol adipate) 13.8%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 2.8%, toluene diisocyanate 5.4%, cyclohexanedimethanol 1.2%, bismuth isooctanoate 0.02%, acetone 35.2%, deionized water 30.58%, polyetheramine D400 0.8%;

[0102] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0103] (1) Add dimer acid polyester, poly(cyclohexanedimethanol adipate) and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0104] (2) In a nitrogen atmosphere, at 60° C., the dimer acid polyester dehydrated by vacuum distillation, the poly(cyclohexanedimethanol adipate) dehydrated by vacuum distillation, the single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, toluene diisocyanate and bismuth isooctanoate were mixed, the temperature was raised to 85° C., and the first heat preservation reaction was carried out for 2 hours;

[0105] (3) In a nitrogen atmosphere, cyclohexanedimethanol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 20 mL / min, and then cooled to 27° C. for a second time;

[0106] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D400 was added, and the mixture was kept warm for a third time at 55° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 283 nm.

[0107] Example 4

[0108] This embodiment provides a water-based polyurethane resin with absorbent grain, the R value of the raw material of which is 1.16, and includes the following components in terms of mass percentage:

[0109] 24.0% of poly(cyclohexanedimethanol adipate) octylpentyl glycol, 3.4% of single-end hydroxyl ethylene oxide-propylene oxide random copolyether, 5.4% of diphenylmethane-4,4′-diisocyanate, 1.2% of neopentyl glycol, 0.03% of bismuth octyl decanoate, 36.0% of acetone, 29.47% of deionized water, and 0.5% of polyetheramine D230;

[0110] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0111] (1) Add poly(cyclohexanedimethanol adipate) and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0112] (2) In a nitrogen atmosphere, at 60° C., poly(cyclohexanedimethanol adipate) dehydrated by vacuum distillation, single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, diphenylmethane-4,4′-diisocyanate and bismuth isooctanoate were mixed, the temperature was raised to 85° C., and the first heat preservation reaction was carried out for 2 hours;

[0113] (3) In a nitrogen atmosphere, neopentyl glycol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 20 mL / min, and then cooled to 27° C. for a second time;

[0114] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D230 was added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain an absorbent waterborne polyurethane resin with a solid content of 50% and an average particle size of 348 nm.

[0115] Example 5

[0116] This embodiment provides a waterborne polyurethane resin with absorbent grain, the R value of the raw material of which is 1.20, and includes the following components in terms of mass percentage:

[0117] Dimer acid polyester 16.7%, polyoctyl pentyl adipate 6.5%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 2.8%, diphenylmethane-4,4′-diisocyanate 4.3%, toluene diisocyanate 1.7%, neopentyl glycol 1.5%, bismuth octyl decanoate 0.02%, acetone 35.2%, deionized water 30.43%, polyetheramine D400 0.85%;

[0118] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0119] (1) Add dimer acid polyester, poly(cyclohexanedimethanol adipate) and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0120] (2) In a nitrogen atmosphere, at 60° C., the dimer acid polyester dehydrated by vacuum distillation, the poly(cyclohexanedimethanol adipate) dehydrated by vacuum distillation, the single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, diphenylmethane-4,4′-diisocyanate, toluene diisocyanate and bismuth octanoate were mixed, the temperature was raised to 85° C., and the first heat preservation reaction was carried out for 2 hours;

[0121] (3) In a nitrogen atmosphere, neopentyl glycol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 20 mL / min, and then cooled to 27° C. for a second time;

[0122] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D400 was added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 335 nm.

[0123] Example 6

[0124] This embodiment provides a water-based polyurethane resin with absorbent grain, the R value of the raw material of which is 1.18, and includes the following components in terms of mass percentage:

[0125] Hexanediol phthalate 22.8%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 3.1%, isophorone diisocyanate 5.2%, toluene diisocyanate 0.9%, cyclohexanedimethanol 1.7%, dibutyltin dilaurate 0.01%, acetone 35.5%, deionized water 30.19%, polyetheramine D400 0.6%;

[0126] The preparation method of the above-mentioned absorbable waterborne polyurethane resin is as follows:

[0127] (1) Add hexanediol phthalate and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by reduced pressure distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0128] (2) In a nitrogen atmosphere, at 60° C., hexanediol phthalate dehydrated by vacuum distillation, single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, diphenylmethane-4,4′-diisocyanate, isophorone diisocyanate and dibutyltin dilaurate were mixed, the temperature was raised to 85° C., and the first heat preservation reaction was carried out for 2 hours;

[0129] (3) In a nitrogen atmosphere, cyclohexanedimethanol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 40 mL / min, and then cooled to 27° C. for a second time;

[0130] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D400 was added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 289 nm.

[0131] Comparative Example 1

[0132] This comparative example provides a waterborne polyurethane resin, which differs from Example 1 only in that:

[0133] Replacing 21.2% of polyneopentyl adipate with 21.2% of polybutylene adipate;

[0134] Finally, a waterborne polyurethane resin with a solid content of 50% and an average particle size of 266 nm was obtained;

[0135] Other conditions are the same as in Example 1.

[0136] Comparative Example 2

[0137] This comparative example provides a waterborne polyurethane resin, which differs from Example 1 only in that:

[0138] Replacing 21.2% of poly(neopentyl adipate) with 21.2% of poly(hexylene adipate) by mass;

[0139] Finally, a waterborne polyurethane resin with a solid content of 50% and an average particle size of 399 nm was obtained;

[0140] Other conditions are the same as in Example 1.

[0141] Comparative Example 3

[0142] This comparative example provides a waterborne polyurethane resin, which differs from Example 1 only in that:

[0143] Replacing 21.2% of polyneopentyl adipate with 21.2% of polypropylene oxide ether polyol;

[0144] Finally, a waterborne polyurethane resin with a solid content of 50% and an average particle size of 421 nm was obtained;

[0145] Other conditions are the same as in Example 1.

[0146] Comparative Example 4

[0147] This comparative example provides a waterborne polyurethane resin, the R value of the raw material of which is 1.85, and includes the following components in terms of mass percentage:

[0148] Poly(neopentyl adipate) 21.2%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 3.1%, isophorone diisocyanate 5.7%, 1,4-butanediol 0.6%, dibutyltin dilaurate 0.03%, acetone 33.1%, deionized water 33.27%, polyetheramine D230 3.1%;

[0149] The preparation method of the above waterborne polyurethane resin is the same as that of Example 1, and finally a waterborne polyurethane resin with a solid content of 50% and an average particle size of 390 nm is obtained.

[0150] Comparative Example 5

[0151] This comparative example provides a waterborne polyurethane resin, the R value of the raw material of which is 1.18, and includes the following components in terms of mass percentage:

[0152] Poly(neopentyl adipate) 21.2%, single-end hydroxyl ethylene oxide-propylene oxide random copolyether 3.0%, isophorone diisocyanate 5.5%, 1,4-butanediol 1.2%, dibutyltin dilaurate 0.03%, acetone 32.1%, deionized water 36.77%, ethylenediamine 0.2%;

[0153] The preparation method of the above-mentioned waterborne polyurethane resin is as follows:

[0154] (1) Add poly(neopentyl adipate) and single-end hydroxyl ethylene oxide-propylene oxide random copolyether into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0155] (2) In a nitrogen atmosphere, at 60° C., poly (neopentyl adipate) dehydrated by vacuum distillation, single-end hydroxyl ethylene oxide-propylene oxide random copolyether dehydrated by vacuum distillation, isophorone diisocyanate and dibutyltin dilaurate were mixed, and the first heat preservation reaction was carried out at 85° C. for 2 h;

[0156] (3) In a nitrogen atmosphere, 1,4-butanediol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 30 mL / min, and then cooled to 27° C. for a second time;

[0157] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Ethylenediamine was then added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 203 nm.

[0158] Comparative Example 6

[0159] This comparative example provides a waterborne polyurethane resin, the R value of the raw material of which is 1.18, and includes the following components in terms of mass percentage:

[0160] Poly(neopentyl adipate) 23.9%, 2,2-dimethylolpropionic acid 0.5%, isophorone diisocyanate 6.3%, 1,4-butanediol 1.65%, dibutyltin dilaurate 0.03%, acetone 34.3%, triethylamine 0.4%, deionized water 32.37%, polyetheramine D230 0.7%;

[0161] The preparation method of the above-mentioned waterborne polyurethane resin is as follows:

[0162] (1) Add poly(neopentyl adipate) into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0163] (2) In a nitrogen atmosphere, at 60° C., poly(neopentyl adipate), isophorone diisocyanate and dibutyltin dilaurate which have been dehydrated by vacuum distillation are mixed, and the mixture is kept warm for a first time at 85° C. for 2 h;

[0164] (3) In a nitrogen atmosphere, 1,4-butanediol and 2,2-dihydroxymethylpropionic acid were added to the reaction system obtained in step (2), and the mixture was kept warm for 1.5 h at 85 °C for the second time, and then cooled to 60 °C for the first time. Then, acetone was added dropwise at a rate of 30 mL / min, and the mixture was cooled to 27 °C for the second time. Then, triethylamine was added, and the mixture was kept warm for 2 min for the third time.

[0165] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D230 was added, and the mixture was kept warm for a fourth time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain an aqueous polyurethane resin with a solid content of 50% and an average particle size of 260 nm.

[0166] Comparative Example 7

[0167] This comparative example provides a waterborne polyurethane resin, the R value of the raw material of which is 1.18, and includes the following components in terms of mass percentage:

[0168] Poly(neopentyl adipate) 21.2%, PEG1000 3.1%, isophorone diisocyanate 5.7%, 1,4-butanediol 1.3%, dibutyltin dilaurate 0.03%, acetone 34.3%, deionized water 33.07%, polyetheramine D230 0.7%;

[0169] The preparation method of the above-mentioned waterborne polyurethane resin is as follows:

[0170] (1) Add poly(neopentyl adipate) and PEG1000 into a four-necked flask equipped with a condenser and a thermometer, dehydrate by vacuum distillation at 110° C. and −0.1 MPa for 1.5 h, and then cool to 60° C.;

[0171] (2) In a nitrogen atmosphere, at 60° C., poly (neopentyl adipate) dehydrated by vacuum distillation, PEG1000 dehydrated by vacuum distillation, isophorone diisocyanate and dibutyltin dilaurate were mixed, and the first heat preservation reaction was carried out at 85° C. for 2 h;

[0172] (3) In a nitrogen atmosphere, 1,4-butanediol was added to the reaction system obtained in step (2), and the mixture was kept warm for a second time at 85° C. for 1.5 h, and then cooled to 60° C. for a first time, and then acetone was added dropwise at a rate of 30 mL / min, and then cooled to 27° C. for a second time;

[0173] (4) In a nitrogen atmosphere, deionized water was added to the reaction system obtained in step (3), and the mixture was stirred at a rotation speed of 2000 rpm until it was completely emulsified. Then, polyetheramine D230 was added, and the mixture was kept warm for a third time at 50° C. for 30 min. Acetone was removed by reduced pressure distillation at -0.1 MPa to obtain a waterborne polyurethane resin with a solid content of 50% and an average particle size of 225 nm.

[0174] Comparative Example 8

[0175] This comparative example provides a waterborne polyurethane resin, which differs from Example 1 only in that:

[0176] The mass percentage of poly(neopentyl adipate) is 22.2%, and the mass percentage of single-end hydroxyl ethylene oxide-propylene oxide random copolyether is 2.0%;

[0177] Finally, a waterborne polyurethane resin with a solid content of 50% and an average particle size of 730 nm was obtained;

[0178] Other conditions are the same as in Example 1.

[0179] Comparative Example 9

[0180] This comparative example provides a waterborne polyurethane resin, which differs from Example 1 only in that:

[0181] The mass percentage of poly(neopentyl adipate) is 20.2%, and the mass percentage of single-end hydroxyl ethylene oxide-propylene oxide random copolyether is 4.0%;

[0182] Finally, a waterborne polyurethane resin with a solid content of 50% and an average particle size of 140 nm was obtained. However, the viscosity of the waterborne polyurethane resin was greater than 1500 cp, and it demulsified when used as a foaming material, and a normal foaming material could not be obtained.

[0183] Other conditions are the same as in Example 1.

[0184] Performance Testing:

[0185] (1) Leather performance:

[0186] 5 wt % of a foaming agent and 1 wt % of a black paste were added to 100 g of the aqueous polyurethane resin provided in the above examples and comparative examples, respectively, and then the same thickener (polyurethane associative thickener BYK7625) was used to thicken the mixture to 1 wcp, and then foaming was started at 2000 rpm with a foaming ratio of 3 times to obtain a foamed resin for use as a synthetic leather foam layer resin.

[0187] The fabric resin required for preparing synthetic leather is Huafeng JF-PDY-1811, and the preparation process of the fabric resin is as follows: add 5wt% of black paste (Shiming black paste LR20) to 100g of water-based polyurethane JF-PDY-1811, stir evenly and use it directly.

[0188] The preparation process of synthetic leather is as follows:

[0189] Step 1: scrape the surface layer; use a 12S scraper to scrape the prepared surface layer resin on the garment leather release paper, dry it at 110℃×4min+140℃×3min, and take it out;

[0190] Step 2: scrape the foaming layer; use an 80S scraper to scrape the prepared foaming layer resin on the baked surface layer, dry it at 80℃×2min+140℃×7min, and take it out;

[0191] Step 3: Use a 60S scraper to scrape the prepared foam layer resin on the baked foam layer. Do not dry it. Directly use 0.65mm weft elastic matte velvet base fabric, fit the smooth surface, gently cover it on the scraped base material, and then dry it at 110℃×2min+140℃×7min, and take it out; pay attention to the warp and weft directions of the base fabric, and it needs to be laminated along the warp direction.

[0192] Step 4: After the leather sample cools to room temperature, peel the leather sample off the release paper and conduct the following tests;

[0193] ① Softness of hand feel: feel the softness and hardness of the leather sample by hand, with Example 1 as the standard sample.

[0194] ② Grain absorption: Cut a 15×15cm sample from the prepared leather sample, heat it in a drying oven at 130℃ / 12s, and then perform vacuum grain absorption to shape it, and observe the clarity of the grain;

[0195] The physical picture of the synthetic leather made of the absorbent waterborne polyurethane resin provided in Example 1 is as follows: Figure 1 As shown, from Figure 1 It can be seen that the texture of the synthetic leather made of the absorbent waterborne polyurethane resin provided in Example 1 is very clear;

[0196] With the above Figure 1 As a standard, the synthetic leathers made of waterborne polyurethane resins provided in other embodiments and comparative examples were scored, and the higher the score, the clearer the texture;

[0197] ③High-temperature recovery of grain: Put the grain-absorbing sample into a 120℃ oven, take it out after heating for 4 minutes, observe the grain recovery and give a score. The higher the score, the clearer the grain after heating.

[0198] (2) Modulus test:

[0199] ① Thickening: Weigh 200g of matured waterborne polyurethane resin into a stirring cup, with the stirring plate about 2cm away from the bottom of the cup. Add thickener BYK0625 in batches at 500rpm until the emulsion viscosity reaches 12000cp, and set aside;

[0200] ② Filtration and degassing: Filter with a 120-mesh filter and degas for 1.5h / 2000rpm to completely degas and obtain the working solution for standby use;

[0201] ③ Film making: Use a 600μm scraper to scrape the spare working liquid onto the mirror release paper, put it into an oven, bake it at room temperature to 50℃ for 10min, 50-70℃ for 10min, 70-90℃ for 10min, 90-110℃ for 5min, 110-130℃ for 5min, and control the heating rate more accurately before taking it out;

[0202] ④Aging test: Place in a 50℃ oven for 12 hours, then put it in a temperature of 20±2℃ and humidity of 65±5% for 1 hour, cut it into two parallel samples of 25×35mm, and test the modulus on the machine.

[0203] (5) Hydrolysis resistance:

[0204] ① Add 5wt% of a foaming agent and 1wt% of a black slurry to 100g of the aqueous polyurethane resin provided in the above embodiment and the comparative example, respectively, and then thicken to 1wcp using the same thickener (polyurethane associative thickener BYK7625), and then start foaming at 2000rpm with a foaming ratio of 3 times to obtain a foamed resin used as a synthetic leather foam layer resin;

[0205] Use a 100S scraper to directly coat the synthetic leather foam layer resin on a 0.65mm weft elastic matte velvet base fabric, dry it at 80°C × 2min + 140°C × 7min, and take out a bass leather sample;

[0206] ② Cut the bass samples into leather samples of 10×10cm in size, cut two leather samples for each sample, place them in a constant temperature and humidity box with a temperature of 70℃ and a humidity of 95%, record the time when the surface of the bass becomes shiny and sticky, and take the average value for record.

[0207] The above performance test results are shown in Table 1 below:

[0208] Table 1

[0209]

[0210]

[0211] “ / ” means that the test cannot be performed.

[0212] From the above content, it can be seen that by designing the raw materials for preparing waterborne polyurethane, further by using specific polyester polyols and single-end hydroxyl hydrophilic polyethers, and controlling the R value and the amount of post-chain extension amine within a specific range, a waterborne polyurethane resin with excellent performance is prepared, and the modulus of the resin is 0.98-1.28 MPa. The synthetic leather prepared from the waterborne polyurethane has a soft feel and strong grain absorption property. The clarity of the grain after grain absorption is 8.5-9.5 points, the grain recovery is low at 120°C, and the hydrolysis resistance is good, specifically 9-11 days.

[0213] It can be seen from the contents of Comparative Examples 1 to 2 that if polyester polyol with weak crystallinity is not used, the prepared waterborne polyurethane resin feels very hard.

[0214] It can be seen from the content of Comparative Example 3 that if polyester polyol is not used but polyether polyol is used instead, the absorbability of the prepared waterborne polyurethane resin is very poor and the non-recovery of the grain at high temperature is also very poor.

[0215] It can be seen from the content of Comparative Example 4 that if the R value of the designed prepolymer is very high, more chain-extending amines are required, the urea bond content is relatively high, and the absorbability of the prepared waterborne polyurethane is relatively poor.

[0216] It can be seen from the content of Comparative Example 5 that if polyetheramine is not used as a post-chain extender, the absorbability of the prepared waterborne polyurethane resin is relatively poor.

[0217] It can be seen from the contents of Comparative Examples 6 to 7 that if the specific hydroxy-terminated ethylene oxide-propylene oxide copolyether is not used as the hydrophilic component, its hydrolysis resistance is very poor.

[0218] It can be seen from the contents of Comparative Examples 8 to 9 that if the content of single-end hydroxyl ethylene oxide-propylene oxide random copolyether is too low, the particle size of the resulting emulsion is too large, the stability is insufficient, and it is easy to demulsify during foaming; if the content of single-end hydroxyl ethylene oxide-propylene oxide random copolyether is too high, the viscosity of the resulting emulsion is too high, and too high viscosity during foaming will also lead to demulsification.

[0219] In summary, in the present invention, the introduction of polyetheramine by post-chain extension can ensure the heat resistance of waterborne polyurethane and reduce urea bonds, thereby ensuring excellent wrinkle fixation. By designing the raw materials for the preparation of waterborne polyurethane, further using specific polyester polyols and single-terminal hydroxyl hydrophilic polyethers, and controlling the R value and the amount of post-chain extension amine within a specific range, a waterborne polyurethane resin with excellent performance is prepared.

[0220] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A water-based polyurethane resin with absorbent grain, characterized in that: Taking the total mass of the raw materials of the absorbent waterborne polyurethane resin as 100%, the raw materials include the following components in the following amounts: The polyester polyol includes any one of polyoctyl pentyl adipate, polyoctyl pentyl adipate cyclohexanedimethanol, hexylene phthalate or dimer acid polyester or a combination of at least two thereof.

2. The absorbable waterborne polyurethane resin according to claim 1, characterized in that: The R value of the raw material of the absorbent waterborne polyurethane resin is 1.16 to 1.22; Preferably, the number average molecular weight of the polyester polyol is 1000 to 3000 g / mol; Preferably, the number average molecular weight of the hydroxy-terminated ethylene oxide-propylene oxide copolyether is 2000 to 4000 g / mol.

3. The absorbable waterborne polyurethane resin according to claim 1 or 2, characterized in that: The alcohol chain extender includes any one of 1,4-butanediol, neopentyl glycol or cyclohexanedimethanol or a combination of at least two thereof; Preferably, the isocyanate includes any one of isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate or diphenylmethane-4,4′-diisocyanate, or a combination of at least two thereof.

4. The absorbent waterborne polyurethane resin according to any one of claims 1 to 3, characterized in that: The post-chain extender includes polyetheramine; Preferably, the solvent comprises water.

5. The absorbent waterborne polyurethane resin according to any one of claims 1 to 4, characterized in that: The raw materials of the absorbable waterborne polyurethane resin also include a catalyst; Preferably, the content of the catalyst in the raw material of the absorbable waterborne polyurethane resin is 0.01 to 0.04%; Preferably, the catalyst comprises any one of dibutyltin dilaurate, bismuth isooctanoate or bismuth octanoate or a combination of at least two thereof.

6. The absorbent waterborne polyurethane resin according to any one of claims 1 to 5, characterized in that: The raw materials of the absorbable waterborne polyurethane resin also include a diluent; Preferably, the content of the diluent in the raw material of the absorbent waterborne polyurethane resin is 32-36%; Preferably, the diluent comprises acetone.

7. A method for preparing the absorbable waterborne polyurethane resin according to any one of claims 1 to 6, characterized in that: The preparation method comprises: mixing polyester polyol, terminal hydroxyl ethylene oxide-propylene oxide copolyether, isocyanate and optional catalyst, performing a first heat preservation reaction, adding an alcohol chain extender, performing a second heat preservation reaction, and then performing a first cooling, adding a solvent, stirring until completely emulsified, and finally adding a post-chain extender, performing a third heat preservation reaction, and obtaining the absorbent waterborne polyurethane resin.

8. The preparation method according to claim 7, characterized in that: The method further comprises a pre-treatment step before the mixing; Preferably, the pretreatment comprises: dehydrating the polyester polyol and the terminal hydroxyl ethylene oxide-propylene oxide copolyether respectively; Preferably, the mixing temperature is 60-65°C; Preferably, the temperature of the first insulation reaction is 80-100° C. and the time is 2-3 hours; Preferably, the temperature of the second insulation reaction is 75-90°C and the time is 1-3h; Preferably, the temperature of the system after the first cooling is 60-65°C; Preferably, after the first cooling, a step of adding a diluent for a second cooling is also included; Preferably, the temperature of the system after the second cooling is 20-30°C.

9. The preparation method according to claim 7 or 8, characterized in that: The stirring speed is 1500-2500 rpm; Preferably, the temperature of the third insulation reaction is 40-60°C and the time is 20-50 minutes; Preferably, after the third insulation reaction, a post-treatment step is also included; Preferably, the post-treatment method comprises vacuum distillation; Preferably, the pressure of the reduced pressure distillation is -0.1 to -0.09 MPa; Preferably, the mixing, the first insulation reaction, the second insulation reaction, the first cooling and the third insulation reaction are all carried out in a protective gas atmosphere; Preferably, the protective gas comprises nitrogen.

10. An application of the absorbent waterborne polyurethane resin according to any one of claims 1 to 6, characterized in that: The application includes the use for preparing the foamed layer of soft synthetic leather.

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