High-stripping solvent-free waterborne polyurethane synthetic leather and preparation method thereof

Abstract

The invention discloses high-stripping solvent-free waterborne polyurethane synthetic leather and a preparation method thereof, and relates to the technical field of polyurethane synthetic leather, the high-stripping solvent-free waterborne polyurethane synthetic leather comprises a component A and a component B according to a weight part ratio of 100: (30-40), the component A is prepared from the following components in parts by weight: 40 to 70 parts of polyhydric alcohol, 25 to 40 parts of diisocyanate, 5 to 8 parts of hydrophilic chain extender, 6 to 10 parts of amino grafted polytetrahydrofuran ether glycol, 0 to 1.5 parts of foaming agent, 0 to 3 parts of trimethylolpropane triacrylate and 0.12 to 0.25 part of catalyst; and the component B is polyester modified MDI, and the content of-NCO is 12 to 15 weight percent. The bonding strength is remarkably improved through the components of the component A and the component B, the process is simple, the catalytic effect of the catalyst is effectively controlled, and therefore the purpose of remarkably improving the peel strength of the synthetic leather is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of polyurethane synthetic leather, and in particular to a high-stripping solvent-free waterborne polyurethane synthetic leather and a preparation method thereof. Background Art

[0002] Solvent-free waterborne polyurethane synthetic leather is a new type of synthetic leather material. It uses waterborne polyurethane as the main film-forming substance. No organic solvents or only a very small amount of organic solvents are used in the preparation process. It is made through a specific process and has similar properties and appearance to natural leather.

[0003] Chinese patent publication number CN108276761B discloses a solvent-free polyurethane resin for leather, a preparation method, and an application thereof. The solvent-free polyurethane resin for leather, the preparation method, and the application thereof comprise a resin component A and a resin component B; component A contains 30% to 45% by weight of a polyether ester polyol-polyisocyanate prepolymer, 50% to 65% by weight of a polyether polyol A, and 0.3% to 2.0% by weight of water; component B contains 20% to 60% by weight of a diisocyanate.

[0004] However, in the solvent-free polyurethane resin for leather, its preparation method and application, component A and component B react only by a simple mixing method, which will lead to poor adhesion of the polyurethane resin for solvent-free synthetic leather, and further cause the synthetic leather prepared by the polyurethane resin to have low peel strength, which needs to be improved. Summary of the Invention

[0005] In view of this, the first object of this application is to provide a highly peelable solvent-free waterborne polyurethane synthetic leather to significantly improve the peel strength of the synthetic leather. The specific solution is as follows:

[0006] A high-stripping solvent-free waterborne polyurethane synthetic leather comprises component A and component B in a weight ratio of 100:30-40;

[0007] The component A comprises, by weight, 40-70 parts of a polyol, 25-40 parts of a diisocyanate, 5-8 parts of a hydrophilic chain extender, 6-10 parts of an amino-grafted polytetramethylene ether glycol, 0-1.5 parts of a foaming agent, 0-3 parts of trimethylolpropane triacrylate, and 0.12-0.25 parts of a catalyst;

[0008] The B component is polyester-modified MDI, and the content of -NCO is 12-15 wt%.

[0009] Preferably, the polyol is 55-70 parts of polyether polyol, 40-50 parts of polyester polyol, or a mixed polyol of 10-15 parts of polyether polyol and 35-45 parts of polyester polyol.

[0010] Preferably, the preparation method of the amino-grafted polytetramethylene ether diol comprises the steps of: ① selecting polytetramethylene ether diol with a molecular weight of no more than 2000, isocyanate, an amino compound, a catalyst, and a solvent for standby use; ② heating the polytetramethylene ether diol to 70-78° C. and stirring for 2-3 hours to obtain clean polytetramethylene ether diol; ③ adding a solvent to the clean polytetramethylene ether diol and dissolving it to obtain a reaction solution, and then adding isocyanate and a catalyst to the reaction solution to obtain polytetramethylene ether diol terminated with an isocyanate group; and ④ adding an amino compound to the isocyanate-terminated polytetramethylene ether diol, controlling the temperature to 25-35° C., and stirring the reaction for 4-6 hours to obtain the amino-grafted polytetramethylene ether diol.

[0011] Preferably: in step 1, the molecular weight of the polytetramethylene ether glycol is 1800 or 1400, purchased from BASF 1400 and 1800; the isocyanate is toluene diisocyanate; the catalyst is dibutyltin dilaurate; and the solvent is DMF or THF.

[0012] Preferably, in step 3, the temperature of the clean polytetramethylene ether diol is first lowered to 20-30° C., and then isocyanate and a catalyst are added. The molar ratio of the isocyanate to the clean polytetramethylene ether diol is 1.0-1.2:1, and the mass percentage of the catalyst is 0.2-0.5wt%. The reaction temperature is controlled at 25-35° C. and the reaction time is 5-6 hours.

[0013] Preferably, in step 4, the amino compound is ethylenediamine; and the molar ratio of the ethylenediamine to the isocyanate-terminated polytetramethylene ether diol is 6-9:20.

[0014] Preferably, the method further comprises step ⑤ of adding a precipitant to the solution, and filtering, washing and vacuum drying the precipitate in sequence to obtain amino-grafted polytetramethylene ether diol.

[0015] Preferably, the diisocyanate is toluene diisocyanate; the hydrophilic chain extender is dimethylolbutyric acid; the blowing agent is azodicarbonamide blowing agent; and the catalyst is dibutyltin dilaurate attached via polyethylene glycol.

[0016] The second object of the present invention is to provide a method for preparing a high-stripping solvent-free waterborne polyurethane synthetic leather, which is used to prepare the high-stripping solvent-free waterborne polyurethane synthetic leather as described above, and is characterized in that it includes preparing component A, preparing component B and mixing; the preparation of component A is as follows: putting polyol into a reaction kettle, heating it to 110-120°C and vacuum dehydrating it for 3-5 hours, then cooling it to 40°C, adding diisocyanate, hydrophilic chain extender, amino-grafted polytetramethylene ether diol and catalyst, stirring it for 2-3 hours to obtain a water content of less than 600p pm component A; the preparation of the B component is as follows: MDI and polyester polyol dehydrated at 100-110°C are mixed at a temperature of 40-50°C, the stirring speed is controlled at 50-100r / min, and after sufficient mixing, the temperature is increased to 70-80°C and the stirring reaction is continued for 2-3h to obtain polyester-modified MDI with an -NCO content of 12-15wt%; the mixed preparation is as follows: after mixing the A component and the B component in proportion, reacting at 60-80°C for 6-12h, coating, drying and curing to obtain synthetic leather.

[0017] Preferably, the catalyst is prepared by adding dibutyltin dilaurate into a polyethylene glycol aqueous solution with a mass concentration of 10%, stirring the mixture sufficiently, filtering the mixture, and drying the mixture to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on its surface.

[0018] From the above scheme, it can be seen that the present application provides a high-stripping solvent-free waterborne polyurethane synthetic leather and a preparation method thereof, and the high-stripping solvent-free waterborne polyurethane synthetic leather and the preparation method thereof have the following beneficial effects:

[0019] 1. By selecting the components of component A and component B, low odor and environmental protection can be achieved in both the production process and the product itself;

[0020] 2. By adding amino-grafted polytetramethylene glycol as a reactive site, a stable cross-linked network structure is formed between it and the various components, so that the peel strength of the high-peel solvent-free waterborne polyurethane synthetic leather is significantly improved;

[0021] 3. By adsorbing polyethylene glycol on the surface of dibutyltin dilaurate, the stability of dibutyltin dilaurate will be improved, and the utilization rate of the catalyst will be significantly improved when components A and B are mixed to prepare synthetic leather, thereby promoting the stability and uniformity of polyurethane synthetic leather during the reaction process, thereby significantly improving the performance consistency of the product and further promoting the improvement of peel strength. DETAILED DESCRIPTION

[0022] The following will be a clear and complete description of the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] It should be noted that the diisocyanate used in the examples of this application is toluene diisocyanate, the hydrophilic chain extender is dimethylolbutyric acid, and the blowing agent is azodicarbonamide. The catalyst is dibutyltin dilaurate. The polyether polyol is polyether-based system material C72063 / 1C-A purchased from BASF. The polyester polyol is SY750 purchased from Shanghai Shuyu Chemical Co., Ltd.

[0024] The molecular weight of polytetramethylene ether glycol is 1800 or 1400 and is purchased from BASF 1400 and 1800. The isocyanate is toluene diisocyanate. The catalyst is dibutyltin dilaurate. The solvent is DMF or THF. The polyester polyol in the polyester-modified MDI is water-based polyester polyol CM-1102 purchased from Zibo Chongmei Polyurethane Technology Co., Ltd. Of course, the sources and composition of the above components do not mean that other similar reagents cannot be used to achieve the desired effect; they are merely for full disclosure.

[0025] The following is a detailed description of a highly strippable solvent-free waterborne polyurethane synthetic leather and a preparation method thereof.

[0026] A high-stripping solvent-free waterborne polyurethane synthetic leather comprises component A and component B in a weight ratio of 100:30-40. Component A comprises 40-70 parts by weight of a polyol, 25-40 parts of a diisocyanate, 5-8 parts of a hydrophilic chain extender, 6-10 parts of amino-grafted polytetramethylene ether glycol, 0-1.5 parts of a foaming agent, 0-3 parts of trimethylolpropane triacrylate, and 0.12-0.25 parts of a catalyst. Component B is polyester-modified MDI with a -NCO content of 12-15% by weight.

[0027] It should be noted that the polyols in the technical solution of this application are 55-70 parts of polyether polyol, 40-50 parts of polyester polyol, or a mixed polyol of 10-15 parts of polyether polyol and 35-45 parts of polyester polyol. Of course, the adjustment of the usage amounts of polyether polyol and polyester polyol lies in the adjustment made to the requirements for the softness and flexibility of synthetic leather. Therefore, the embodiments of this application are all implemented using a mixed polyol of 10-15 parts of polyether polyol and 35-45 parts of polyester polyol.

[0028] The preparation method of amino-grafted polytetramethylene ether diol comprises the following steps: ① selecting polytetramethylene ether diol with a molecular weight not greater than 2000, isocyanate, amino compound, catalyst, and solvent for standby use; ② heating the polytetramethylene ether diol to 70-78° C. and stirring for 2-3 hours to obtain clean polytetramethylene ether diol; ③ adding solvent to the clean polytetramethylene ether diol and dissolving it to obtain a reaction solution, wherein the temperature of the reaction solution is 20-30° C., and then adding isocyanate and catalyst to the reaction solution, wherein the molar ratio of isocyanate to clean polytetramethylene ether diol is 0.05; and The method comprises the following steps: step 4, adding an amino compound to the isocyanate-terminated polytetrahydrofuran ether diol, controlling the temperature to be 25-35° C., and stirring the reaction for 4-6 hours to obtain amino-grafted polytetrahydrofuran ether diol; and step 5, adding a precipitant to the solution, and filtering, washing, and vacuum-drying the precipitate to obtain amino-grafted polytetrahydrofuran ether diol.

[0029] In the embodiment of the present application, the amino compound is ethylenediamine, and the molar ratio of ethylenediamine to isocyanate-terminated polytetramethylene ether glycol is 6-9:20.

[0030] A method for preparing a high-stripping solvent-free waterborne polyurethane synthetic leather, used for preparing the high-stripping solvent-free waterborne polyurethane synthetic leather as described above, comprises preparing component A, preparing component B, and mixing. The preparation of component A comprises: adding a polyol into a reaction kettle, heating it to 110-120° C. and vacuum dehydrating it for 3-5 hours, then cooling it to 40° C., adding a diisocyanate, a hydrophilic chain extender, amino-grafted polytetramethylene ether diol, and a catalyst, and stirring it for 2-3 hours to obtain component A having a water content of less than 600 ppm. Component B is prepared by mixing MDI with a polyester polyol dehydrated at 100-110°C at 40-50°C, stirring at 50-100 r / min, raising the temperature to 70-80°C and continuing the reaction with stirring for 2-3 hours to obtain polyester-modified MDI with an -NCO content of 12-15 wt%. Component A and component B are mixed in proportion, reacting at 60-80°C for 6-12 hours, coating, drying, and curing to obtain synthetic leather. The catalyst is dibutyltin dilaurate added to a 10% polyethylene glycol aqueous solution, stirred thoroughly, filtered, and dried to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on its surface.

[0031] Example 1

[0032] A high-stripping solvent-free waterborne polyurethane synthetic leather comprises component A and component B in a weight ratio of 100:30. Component A comprises 10 parts by weight of a polyether polyol, 35 parts of a polyester polyol, 25 parts of a diisocyanate, 5 parts of a hydrophilic chain extender, 6 parts of amino-grafted polytetramethylene ether glycol, 0.2 parts of a foaming agent, 1 part of trimethylolpropane triacrylate, and 0.12 parts of a catalyst. Component B is polyester-modified MDI with a -NCO content of 14.1 wt%.

[0033] The preparation method of amino-grafted polytetramethylene ether diol comprises the following steps: ① selecting polytetramethylene ether diol, isocyanate, amino compound, catalyst, and solvent for standby use; ② heating the polytetramethylene ether diol to 70°C and stirring for 3h to obtain clean polytetramethylene ether diol; ③ adding solvent to the clean polytetramethylene ether diol and dissolving it to obtain a reaction solution, wherein the temperature of the reaction solution is 20°C, and then adding isocyanate and catalyst to the reaction solution, and the molar ratio of isocyanate to clean polytetramethylene ether diol is 0.05. The method comprises the following steps: adding an amino compound to the isocyanate-terminated polytetrahydrofuran ether diol, controlling the temperature to be 25° C., and stirring the reaction for 6 hours to obtain amino-grafted polytetrahydrofuran ether diol; adding a precipitant to the solution, and filtering, washing, and vacuum-drying the precipitate to obtain amino-grafted polytetrahydrofuran ether diol.

[0034] In the embodiment of the present application, the amino compound is ethylenediamine, and the molar ratio of ethylenediamine to isocyanate-terminated polytetramethylene ether glycol is 6:20.

[0035] A method for preparing high-stripping solvent-free waterborne polyurethane synthetic leather, used to prepare the above-described high-stripping solvent-free waterborne polyurethane synthetic leather, comprises preparing component A, component B, and a mixing process. Component A is prepared by placing a polyol into a reactor, heating it to 110°C and vacuum dehydrating it for 5 hours. The temperature is then lowered to 40°C, followed by the addition of a diisocyanate, a hydrophilic chain extender, amino-grafted polytetramethylene glycol, and a catalyst. After stirring for 2 hours, component A having a water content of less than 600 ppm is obtained. Component B is prepared by mixing MDI with a polyester polyol that has been dehydrated at 100°C at 40°C, stirring at 50 rpm. After thorough mixing, the temperature is raised to 70°C and the reaction is continued with stirring for 3 hours to obtain a polyester-modified MDI with an -NCO content of 14.1 wt%. The mixing process is prepared by mixing components A and B in a proportional manner, reacting them at 60°C for 12 hours, coating, drying, and curing to obtain the synthetic leather. The catalyst is prepared by adding dibutyltin dilaurate into a polyethylene glycol aqueous solution with a mass concentration of 10%, stirring the mixture sufficiently, filtering the mixture, and drying the mixture to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on the surface.

[0036] Example 2

[0037] A high-stripping solvent-free waterborne polyurethane synthetic leather comprises component A and component B in a weight ratio of 100:35. Component A comprises 13 parts by weight of a polyether polyol, 40 parts of a polyester polyol, 33 parts of a diisocyanate, 6 parts of a hydrophilic chain extender, 8 parts of amino-grafted polytetramethylene ether glycol, 1.0 part of a foaming agent, 2 parts of trimethylolpropane triacrylate, and 0.18 parts of a catalyst. Component B is polyester-modified MDI with a -NCO content of 14.1 wt%.

[0038] The preparation method of amino-grafted polytetramethylene ether diol comprises the following steps: ① selecting polytetramethylene ether diol, isocyanate, amino compound, catalyst, and solvent for standby use; ② heating the polytetramethylene ether diol to 75° C. and stirring for 2.5 hours to obtain clean polytetramethylene ether diol; ③ adding solvent to the clean polytetramethylene ether diol and dissolving it to obtain a reaction solution, wherein the temperature of the reaction solution is 25° C., and then adding isocyanate and catalyst to the reaction solution, and the molar ratio of isocyanate to clean polytetramethylene ether diol is 0.05. The method comprises the following steps: adding an amino compound to the isocyanate-terminated polytetrahydrofuran ether diol, controlling the temperature to be 30° C., and reacting for 5.5 h to obtain an amino-grafted polytetrahydrofuran ether diol; adding a precipitant to the solution, and filtering, washing, and vacuum-drying the precipitate to obtain the amino-grafted polytetrahydrofuran ether diol.

[0039] In the embodiment of the present application, the amino compound is ethylenediamine, and the molar ratio of ethylenediamine to isocyanate-terminated polytetramethylene ether glycol is 2:5.

[0040] A method for preparing high-stripping solvent-free waterborne polyurethane synthetic leather, used to prepare the above-described high-stripping solvent-free waterborne polyurethane synthetic leather, comprises preparing component A, component B, and a mixing process. Component A is prepared by placing a polyol into a reactor, heating it to 115°C and vacuum dehydrating it for 4 hours. The temperature is then lowered to 40°C, followed by the addition of a diisocyanate, a hydrophilic chain extender, amino-grafted polytetramethylene glycol, and a catalyst. After stirring for 2.5 hours, component A having a water content of less than 600 ppm is obtained. Component B is prepared by mixing MDI with a polyester polyol that has been dehydrated at 105°C at 44°C, stirring at 70 rpm. After thorough mixing, the temperature is raised to 75°C and the reaction is continued with stirring for 2.5 hours to obtain a polyester-modified MDI with an -NCO content of 14.1 wt%. The mixing process involves mixing components A and B in appropriate proportions, reacting them at 70°C for 8 hours, coating, drying, and curing to obtain the synthetic leather. The catalyst is prepared by adding dibutyltin dilaurate into a polyethylene glycol aqueous solution with a mass concentration of 10%, stirring the mixture sufficiently, filtering the mixture, and drying the mixture to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on the surface.

[0041] Example 3

[0042] A high-stripping solvent-free waterborne polyurethane synthetic leather comprises component A and component B in a ratio of 100:40 by weight. Component A comprises 15 parts by weight of a polyether polyol, 45 parts of a polyester polyol, 40 parts of a diisocyanate, 8 parts of a hydrophilic chain extender, 10 parts of amino-grafted polytetramethylene ether glycol, 1.5 parts of a foaming agent, 3 parts of trimethylolpropane triacrylate, and 0.25 parts of a catalyst. Component B is polyester-modified MDI with a -NCO content of 14.1 wt%.

[0043] The preparation method of amino-grafted polytetramethylene ether diol comprises the following steps: ① selecting polytetramethylene ether diol, isocyanate, amino compound, catalyst, and solvent for standby use; ② heating the polytetramethylene ether diol to 78° C. and stirring for 2 h to obtain clean polytetramethylene ether diol; ③ adding solvent to the clean polytetramethylene ether diol and dissolving it to obtain a reaction solution, wherein the temperature of the reaction solution is 30° C., and then adding isocyanate and catalyst to the reaction solution, and the molar ratio of isocyanate to clean polytetramethylene ether diol is 0.05. The method comprises the following steps: adding an amino compound to the isocyanate-terminated polytetrahydrofuran ether diol, controlling the temperature to be 35° C., and stirring the reaction for 4 hours to obtain amino-grafted polytetrahydrofuran ether diol; and adding a precipitant to the solution, and filtering, washing, and vacuum-drying the precipitate to obtain amino-grafted polytetrahydrofuran ether diol.

[0044] In the embodiment of the present application, the amino compound is ethylenediamine, and the molar ratio of ethylenediamine to isocyanate-terminated polytetramethylene ether glycol is 9:20.

[0045] A method for preparing high-stripping solvent-free waterborne polyurethane synthetic leather, used to prepare the high-stripping solvent-free waterborne polyurethane synthetic leather described above, comprises preparing component A, component B, and a mixing process. Component A is prepared by placing a polyol into a reactor, heating it to 120°C and vacuum dehydrating it for 3 hours. The temperature is then lowered to 40°C, followed by the addition of a diisocyanate, a hydrophilic chain extender, amino-grafted polytetramethylene glycol, and a catalyst. After stirring for 3 hours, component A is obtained, having a water content of less than 600 ppm. Component B is prepared by mixing MDI with a polyester polyol that has been dehydrated at 110°C at 50°C, stirring at 100 rpm. After thorough mixing, the temperature is raised to 80°C and the reaction is continued with stirring for 2 hours, yielding a polyester-modified MDI with an -NCO content of 14.1 wt%. The mixing process involves mixing components A and B in appropriate proportions, reacting them at 80°C for 6 hours, coating, drying, and curing to obtain the synthetic leather. The catalyst is prepared by adding dibutyltin dilaurate into a polyethylene glycol aqueous solution with a mass concentration of 10%, stirring the mixture sufficiently, filtering the mixture, and drying the mixture to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on the surface.

[0046] Comparative Example 1

[0047] The difference between Comparative Example 1 and Example 2 is that in Comparative Example 1, polytetramethylene glycol is used instead of amino-grafted polytetramethylene glycol.

[0048] Comparative Example 2

[0049] The difference between Comparative Example 2 and Example 2 is that the catalyst used in Comparative Example 2 is dibutyltin dilaurate without polyethylene glycol adsorbed on its surface.

[0050] Comparative Example 3

[0051] The difference between Comparative Example 3 and Example 2 is that amino-grafted polytetramethylene ether glycol is not added in Comparative Example 3.

[0052] Performance Testing

[0053] Performance tests were conducted on Examples 1 to 3 and Comparative Examples 1 to 3. The performance tests included a peel load test, a modulus test, and a heat resistance test. The test results are shown in Table 1 below.

[0054] Table 1 Performance test results

[0055] Peel load / N / 3cm Modulus / N / 3cm Heat resistance / ℃ Example 1 129 43 235 Example 2 134 45 235 Example 3 137 46 235 Comparative Example 1 130 28 225 Comparative Example 2 122 40 220 Comparative Example 3 118 43 220

[0056] Table 1 above shows that the addition of polytetramethylene glycol improves the peel strength of the prepared synthetic leather, but significantly reduces its modulus. However, the use of amino-grafted polytetramethylene glycol simultaneously improves both the modulus and the peel load. Furthermore, dibutyltin dilaurate, which has been surface-adsorbed with polyethylene glycol, also improves the peel strength and modulus of the synthetic leather. This indicates that dibutyltin dilaurate, which has been surface-adsorbed with polyethylene glycol as a catalyst and is uniformly dispersed in component A, significantly enhances its catalytic effect, thereby improving the mechanochemical properties of the synthetic leather.

[0057] In summary, the present application provides a high-peeling solvent-free waterborne polyurethane synthetic leather and a preparation method thereof, wherein the high-peeling solvent-free waterborne polyurethane synthetic leather and a preparation method thereof are selected by the constituents of component A and component B, thereby achieving low odor and environmentally friendly effects in both the production process and the product itself. Wherein, due to the addition of amino-grafted polytetramethylene ether glycol as a reactive site, a stable cross-linked network structure is formed between it and each component, so that the high-peeling solvent-free waterborne polyurethane synthetic leather achieves the purpose of significantly improving peel strength. At the same time, by adopting polyethylene glycol adsorbed on the surface of dibutyltin dilaurate, the stability of dibutyltin dilaurate is improved, and the utilization rate of the catalyst is significantly improved when component A and component B are mixed to prepare synthetic leather, thereby promoting the stability and uniformity of polyurethane synthetic leather during the reaction process, thereby significantly improving the performance consistency of the product, and then promoting the improvement of peel strength.

[0058] References to "first," "second," "third," "fourth," and the like (if any) herein are intended to distinguish similar objects and are not necessarily intended to describe a particular order or precedence. It should be understood that the numbers used in this manner are interchangeable where appropriate so that the embodiments described herein can be implemented in an order other than that described herein. In addition, the terms "including" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions, e.g., a process, method, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, or apparatus.

[0059] It should be noted that the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0060] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A high-peeling solvent-free waterborne polyurethane synthetic leather, characterized by: The invention comprises component A and component B in a weight ratio of 100:30-40; The component A comprises, by weight, 40-70 parts of a polyol, 25-40 parts of a diisocyanate, 5-8 parts of a hydrophilic chain extender, 6-10 parts of an amino-grafted polytetramethylene ether glycol, 0-1.5 parts of a foaming agent, 0-3 parts of trimethylolpropane triacrylate, and 0.12-0.25 parts of a catalyst; The B component is polyester-modified MDI, and the -NCO content is 12-15 wt %.

2. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 1, characterized in that: The polyol is 55-70 parts of polyether polyol, 40-50 parts of polyester polyol or a mixed polyol of 10-15 parts of polyether polyol and 35-45 parts of polyester polyol.

3. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 1, characterized in that: The preparation method of the amino-grafted polytetramethylene ether diol comprises the steps of: ① selecting polytetramethylene ether diol with a molecular weight not greater than 2000, isocyanate, an amino compound, a catalyst, and a solvent for standby use; ② heating the polytetramethylene ether diol to 70-78° C. and stirring for 2-3 hours to obtain clean polytetramethylene ether diol; Step ③ Add a solvent to the clean polytetramethylene ether diol and dissolve it to obtain a reaction solution, then add an isocyanate and a catalyst to the reaction solution to obtain polytetramethylene ether diol with an isocyanate group; Step ④ Add an amino compound to the polytetramethylene ether diol with an isocyanate group, control the temperature to 25-35° C., stir and react for 4-6 hours to obtain amino-grafted polytetramethylene ether diol.

4. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 3, characterized in that: In step 1, the molecular weight of the polytetramethylene ether glycol is 1800 or 1400, and it is purchased from BASF as PolyTHF® 1400 and PolyTHF® 1800; the isocyanate is toluene diisocyanate; the catalyst is dibutyltin dilaurate; and the solvent is DMF or THF.

5. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 3, characterized in that: In step 3, the temperature of the clean polytetramethylene ether diol is first lowered to 20-30° C., and then isocyanate and a catalyst are added. The molar ratio of the isocyanate to the clean polytetramethylene ether diol is 1.0-1.2:1, and the mass percentage of the catalyst is 0.2-0.5wt%. The reaction temperature is controlled at 25-35° C. and the reaction time is 5-6 hours.

6. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 3, characterized in that: In step 4, the amino compound is ethylenediamine; and the molar ratio of the ethylenediamine to the isocyanate-terminated polytetramethylene ether diol is 6-9:

20.

7. The high-peeling solvent-free waterborne polyurethane synthetic leather according to claim 3, characterized in that: The method further comprises the step ⑤ of adding a precipitant into the solution, and filtering, washing and vacuum drying the precipitate in sequence to obtain amino-grafted polytetramethylene ether diol.

8. The high-peelable solvent-free waterborne polyurethane synthetic leather according to claim 1, characterized in that: The diisocyanate is toluene diisocyanate; the hydrophilic chain extender is dimethylolbutyric acid; the foaming agent is azodicarbonamide foaming agent; and the catalyst is dibutyltin dilaurate attached via polyethylene glycol.

9. A method for preparing a high-stripping solvent-free waterborne polyurethane synthetic leather, for preparing the high-stripping solvent-free waterborne polyurethane synthetic leather according to any one of claims 1 to 8, characterized in that: The method comprises the preparation of component A, component B and mixed preparation. The preparation of component A comprises the following steps: adding polyol into a reaction kettle, heating to 110-120°C and performing vacuum dehydration for 3-5 hours, cooling to 40°C, adding diisocyanate, a hydrophilic chain extender, amino-grafted polytetramethylene ether diol and a catalyst, and stirring for 2-3 hours to obtain component A having a water content of less than 600 ppm. The preparation of component B comprises the following steps: mixing MDI and polyester polyol dehydrated at 100-110°C at a temperature of 40-50°C, controlling the stirring speed to 50-100 r / min, raising the temperature to 70-80°C after thorough mixing, and continuing stirring for 2-3 hours to obtain polyester-modified MDI having an -NCO content of 12-15 wt%. The mixed preparation comprises the following steps: mixing components A and B in proportion, reacting at 60-80°C for 6-12 hours, coating, drying and curing to obtain synthetic leather.

10. The method for preparing a highly strippable solvent-free waterborne polyurethane synthetic leather according to claim 9, wherein: The catalyst is prepared by adding dibutyltin dilaurate into a polyethylene glycol aqueous solution with a mass concentration of 10%, stirring the mixture sufficiently, filtering the mixture, and drying the mixture to obtain dibutyltin dilaurate with polyethylene glycol adsorbed on its surface.