Thermal-aging-resistant polyurethane resin as well as preparation method and application thereof

Abstract

The invention discloses thermal-aging-resistant polyurethane resin as well as a preparation method and application thereof. The thermal aging resistant polyurethane resin is prepared from the following components in parts by mass: 15 to 45 parts of polyether polyol with a number-average molecular weight of 1000 to 2000, 40 to 70 parts of polyether polyol with a number-average molecular weight of 3000 to 4000, 5 to 15 parts of polycarbonate polyol, 5 to 8 parts of a chain extender, 340 to 430 parts of a solvent, 30 to 50 parts of isocyanate, 0.1 to 0.5 part of an antioxidant, 0.1 to 0.5 part of a catalyst and 0.1 to 0.5 part of a terminating agent. The thermal-aging-resistant polyurethane resin has a high softening point, and can solve the problem that the peel strength of the existing wet-process polyurethane resin finished leather is close to the lower limit after a high-temperature grain-absorbing embossing process.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane, and in particular relates to a heat-aging resistant polyurethane resin and a preparation method and application thereof. Background Art

[0002] Polyurethane (PU) synthetic leather is a new type of polymer composite material similar to natural leather, which is made of fiber fabric as the base material and PU resin as the surface coating by wet and dry processes. It has excellent mechanical properties such as excellent adhesion to the base material, wear resistance, flex resistance, and aging resistance. It also has the advantages of easy processing, uniform quality, and low price. It is an ideal substitute for natural leather.

[0003] Polyether polyurethane resin has a longer service life in a humid environment because it does not contain ester groups or other easily hydrolyzed groups in its molecular structure; the large number of ether bonds in its molecular structure makes the interaction between molecular chains more flexible, increasing the flexibility and elasticity of the material; polyether polyurethane resin usually has a higher molecular weight and a lower degree of crosslinking, a longer molecular chain length and fewer crosslinking points. This structure makes the resin easier to deform and stretch, and therefore has better softness. In daily use, polyether wet polyurethane resin is widely used in the sofa leather field because it can provide excellent softness, elasticity and hydrolysis resistance.

[0004] However, in the existing sofa leather preparation process, most of them are prepared by high-temperature (generally 130-180°C) suction embossing process after dry veneer. Since the resin softening point is not high enough, it is easy to cause high-temperature aging after the high-temperature suction embossing process, resulting in the peeling strength of the finished leather not meeting the standard. Summary of the invention

[0005] In view of this, the primary purpose of the present invention is to provide a heat-resistant polyurethane resin, which has a higher softening point and can solve the problem of lower peel strength of traditional polyether wet polyurethane resin leather after high-temperature suction embossing process.

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

[0007] The present invention first provides a heat-aging resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0008] 15-45 parts of polyether polyol with a number average molecular weight of 1000-2000, 40-70 parts of polyether polyol with a number average molecular weight of 3000-4000, 5-15 parts of polycarbonate polyol, 5-8 parts of chain extender, 340-430 parts of solvent, 30-50 parts of isocyanate, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of catalyst and 0.1-0.5 parts of terminator.

[0009] In a further embodiment, the polyether polyol is a polyether diol.

[0010] In a further embodiment, the polyether diol is polytetrahydrofuran diol or polypropylene glycol.

[0011] In a further embodiment, the polycarbonate polyol is a polycarbonate diol.

[0012] In a further embodiment, the number average molecular weight of the polycarbonate diol is 1000-3000.

[0013] In a further embodiment, the chain extender is one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, and 3-methyl-1,5-pentanediol.

[0014] In a further embodiment, the chain extender is ethylene glycol.

[0015] In a further embodiment, the solvent is one of γ-butyrolactone, N,N-dimethylformamide, ε-caprolactone, dipropylene glycol dimethyl ether, propylene glycol methyl ether acetate, propylene glycol diacetate, and ethylene glycol diacetate.

[0016] In a further embodiment, the isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

[0017] In a further embodiment, the catalyst is a bismuth, zinc or amine catalyst.

[0018] The present invention further provides a method for preparing the aforementioned heat aging resistant polyurethane resin, comprising the following steps:

[0019] S1. Add polyether polyol with a number average molecular weight of 1000-2000 and antioxidant to a solvent accounting for 15%-25% of the total solvent, mix well, add isocyanate accounting for 20%-25% of the total isocyanate, react at 70-80° C. for 30-50 minutes, add polyether polyol with a number average molecular weight of 3000-4000, continue to react for 30-50 minutes, and generate a prepolymer;

[0020] S2, add chain extender, solvent accounting for 35%-45% of the total solvent, and polycarbonate polyol accounting for 8%-12% of the total soft segment to the prepolymer, stir evenly, add isocyanate accounting for 70%-80% of the total isocyanate to carry out chain extension reaction; after reacting for 30-50 minutes, add catalyst and continue to react for 30-50 minutes, and then continue to add isocyanate. When the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After reaching cps / 75℃, stop adding isocyanate, add the remaining solvent and the terminator to terminate the reaction, and obtain the polyether type heat-resistant polyurethane resin.

[0021] The present invention further provides the use of the aforementioned heat-aging resistant polyurethane resin or the heat-aging resistant polyurethane resin prepared by the aforementioned preparation method in the preparation of synthetic leather.

[0022] In a further embodiment, the synthetic leather is sofa leather.

[0023] The present invention further provides a synthetic leather containing the aforementioned heat-aging resistant polyurethane resin or the heat-aging resistant polyurethane resin prepared by the aforementioned preparation method.

[0024] In a further embodiment, the synthetic leather is sofa leather.

[0025] Beneficial effects of the present invention:

[0026] The heat-aging-resistant polyurethane resin of the present invention adopts high and low molecular weight polyether polyols as the main soft segment structure, wherein the high molecular weight (number average molecular weight 3000-4000) polyether polyol has a longer molecular chain length and a larger intermolecular force, which can enhance the cohesion of the material; while the low molecular weight (number average molecular weight 1000-2000) polyether polyol has a shorter molecular weight, which makes it easier to penetrate into the microstructure of the material, so that the resin can be better combined with the cloth base surface, improve the surface adhesion, and ensure the peeling strength. In addition, the long chain structure of the high molecular weight polyether polyol is more likely to form a complex entanglement network, so that the material needs more energy to make the chain segment move when heated, which is manifested in the macroscopic view as the softening point of the resin itself is improved, thereby enhancing the heat resistance of the polyurethane resin, so that when the synthetic leather is subsequently prepared, even after a high temperature process, the peeling strength will not be reduced. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] The present invention first provides a heat-aging resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0030] 15-45 parts of polyether polyol with a number average molecular weight of 1000-2000, 40-70 parts of polyether polyol with a number average molecular weight of 3000-4000, 5-15 parts of polycarbonate polyol, 5-8 parts of chain extender, 340-430 parts of solvent, 30-50 parts of isocyanate, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of catalyst and 0.1-0.5 parts of terminator.

[0031] The heat-aging resistant polyurethane resin introduces a specific ratio of high and low molecular weight polyether polyols into the polyurethane resin system. By matching the two molecular weight polyether polyols, the softening point of the resin itself is improved, the heat resistance of the polyurethane resin is enhanced, and the problem of resin aging caused by high temperature process in the subsequent processing process causing the peel strength to deviate from the lower limit is avoided. Specifically, the invention uses two high and low molecular weight polyether polyols in combination. On the basis of the original single low molecular weight polyether polyol synthesis prepolymer, the introduction of high molecular weight polyether polyol in the second stage of prepolymerization disrupts the regular chain segments formed by low molecular weight polyether polyol and isocyanate. Compared with the chain segments synthesized by low molecular weight polyether polyol and isocyanate, the newly synthesized chain segments are longer, more complex, have more crosslinking points, and have stronger intermolecular forces. The macroscopic performance is that the softening point of the resin is significantly improved.

[0032] The polyether polyol described herein is preferably a polyether diol commonly used in the art for preparing polyurethane resins, and a specific example may be polytetrahydrofuran diol. The selection of a specific polyether polyol may also be based on the performance requirements for preparing synthetic leather, which will not be specifically described here. Preferably, the total polyether polyol accounts for 80% to 95% of the total amount of the polyurethane resin soft segment.

[0033] The polycarbonate polyol described herein is preferably a polycarbonate diol commonly used in the art for preparing polyurethane resins. In some specific embodiments of the present invention, the number average molecular weight of the polycarbonate diol is 1000 to 3000. The carbonate group in the molecular structure of the polycarbonate polyol can give the material a certain hardness and strength. The urethane bond generated by the reaction of the hydroxyl group contained in the polycarbonate polyol with the isocyanate group has a strong hydrogen bond effect, which enhances the interaction between the polyurethane segments and can improve the peel strength; and the introduction of the polycarbonate polyol makes the hard segment and the soft segment form a more uniform distribution at the microscopic level, improving the overall mechanical properties including the peel strength.

[0034] The chain extender described herein, also known as a chain extender or chain elongator, refers to a substance commonly used in the preparation of polyurethane resins that can react with functional groups on polymer chains to extend the molecular chain and increase the molecular weight. Preferably, it is a diol chain extender, and specific examples include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, and 3-methyl-1,5-pentanediol, but are not limited thereto. More preferably, in some specific embodiments of the present invention, according to the different specific performance requirements of synthetic leather, the preferred chain extender is ethylene glycol, which has low rebound performance, can take into account the rigid strength of the resin and the appropriate post-processing performance, and is suitable for use in the preparation of synthetic leather products such as sofa leather.

[0035] The solvent described herein may be a commonly used solvent for preparing polyurethane resins well known in the art, and specific examples include but are not limited to one of γ-butyrolactone, N,N-dimethylformamide, ε-caprolactone, dipropylene glycol dimethyl ether, propylene glycol methyl ether acetate, propylene glycol diacetate, and ethylene glycol diacetate.

[0036] The isocyanate described herein refers to a common raw material in the preparation of polyurethane resin, without any particular limitation, and is preferably a diisocyanate, for example, an aromatic diisocyanate, an aromatic aliphatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, or a derivative or modified product of these diisocyanates, etc. In some specific embodiments of the present invention, the isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate, but is not limited thereto.

[0037] It is understandable that the amount of isocyanate and chain extender added can be adjusted accordingly according to the amount of polyol added, and the amount of solvent used can be adjusted according to the reaction requirements and the solid content of the polyurethane resin, etc., which will not be elaborated here one by one.

[0038] The catalyst described herein is an auxiliary agent commonly used in the preparation of polyurethane to improve the reaction efficiency and preparation effect, for example, it can be a bismuth, zinc or amine catalyst.

[0039] It is understandable that the antioxidants and terminators described in this article are both auxiliary agents commonly used in the preparation of polyurethane, and can be selected and used according to needs. For example, the terminator can be methanol, which will not be elaborated here one by one.

[0040] In addition, the amounts of catalyst, antioxidant and terminator added in the present invention are the amounts commonly used in the preparation of polyurethane resins in the art, and will not be elaborated in detail here.

[0041] Preferably, the solid content of the heat-resistant polyurethane resin in the present invention is 20% to 30%, and its viscosity is 3×10 4 ~8×10 4 cps / 25℃.

[0042] The second aspect of the present invention provides a method for preparing the heat-aging resistant polyurethane resin according to the first aspect of the present invention, comprising the following steps:

[0043] S1. Add polyether polyol with a number average molecular weight of 1000-2000 and antioxidant to a solvent accounting for 15%-25% of the total solvent, mix well, add isocyanate accounting for 20%-25% of the total isocyanate, react at 70-80° C. for 30-50 minutes, add polyether polyol with a number average molecular weight of 3000-4000, continue to react for 30-50 minutes, and generate a prepolymer;

[0044] S2, add chain extender, solvent accounting for 35%-45% of the total solvent, and polycarbonate polyol accounting for 8%-12% of the total soft segment to the prepolymer, stir evenly, add isocyanate accounting for 70%-80% of the total isocyanate to carry out chain extension reaction; after reacting for 30-50 minutes, add catalyst and continue to react for 30-50 minutes, and then continue to add isocyanate. When the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After reaching cps / 75℃, stop adding isocyanate, add the remaining solvent and the terminator to terminate the reaction, and obtain the heat-aging resistant polyurethane resin.

[0045] The preparation of the polyurethane resin in the present invention innovatively adopts a staged prepolymerization preparation method in the prepolymerization stage, that is, a low molecular weight polyether polyol is first fully reacted with an excess of isocyanate, and then a high molecular weight polyether polyol is added to continue the reaction, and a chain extension reaction is performed after the reaction is sufficient; excessive prepolymerization can form a large amount of prepolymer in a short time, thereby accelerating the reaction rate and shortening the reaction time, and ensuring that there are always enough reactants participating in the reaction, thereby improving the utilization rate of the reactants; and excessive reaction is also helpful to regulate the molecular structure and distribution of the prepolymer, so as to optimize the comprehensive performance of the polyurethane resin.

[0046] In addition, the present invention adds the polycarbonate polyol in the chain extension stage so that it does not participate in the prepolymerization stage reaction, which can effectively control the molecular weight of the polymer, improve the strength and toughness of the resin, improve the quality and stability of the polyurethane resin product, and ensure the chemical corrosion resistance and excellent mechanical properties of the subsequent finished leather.

[0047] The fourth aspect of the present invention provides the use of the aforementioned heat-aging resistant polyurethane resin or the heat-aging resistant polyurethane resin prepared by the aforementioned preparation method in the preparation of synthetic leather products.

[0048] Preferably, the synthetic leather is sofa leather. This is because polyether polyols have good hydrolysis resistance, flexibility and elasticity, and can maintain softness even at low temperatures, thus giving the synthetic leather excellent wear resistance, making it very suitable for preparing synthetic leather products such as sofa leather.

[0049] The present invention further provides a synthetic leather, comprising the aforementioned heat-aging resistant polyurethane resin or the heat-aging resistant polyurethane resin prepared by the aforementioned preparation method. Preferably, the synthetic leather is sofa leather, and the heat-aging resistant polyurethane resin in the present invention has a higher softening point, which can solve the problem that the peel strength of the polyurethane resin deviates from the lower limit after being subjected to a high-temperature process.

[0050] It is understandable that there is no particular limitation on the specific formula and process of the synthetic leather, and the formula and process known in the art can be used, which will not be elaborated in detail here.

[0051] The present invention is described below by means of specific examples. It should be noted that the following specific examples are only for illustrative purposes and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods without specific conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial channels.

[0052] The raw material information and manufacturers used in the following examples are as follows:

[0053] The models of polytetramethylene glycol are PTMG-1000, PTMG-2000, PTMG-3000 and PTMG-4000, with number average molecular weights of 1000, 2000, 3000 and 4000, respectively, Shandong Deyitai New Materials Co., Ltd.

[0054] The polycarbonate diol model is AS-202, with a number average molecular weight of 2000, and is from Asahi Kasei Corporation of Japan.

[0055] The catalyst model is MB20, an organic catalyst produced by Air Products and Chemicals, Inc. of the United States.

[0056] The isocyanate model is MDI, diphenylmethane diisocyanate produced by Wanhua Chemical.

[0057] The antioxidant model is Chinox 1010, produced by Double Bond Chemical Co., Ltd., Taiwan Province, China.

[0058] The above reagents are only for illustrating the sources and components of the reagents used in the embodiments of the present invention so as to fully disclose the present invention. It does not mean that only the above reagents can be used. Other similar reagents or reagents provided by other suppliers can achieve the purpose of the present invention. The specific protection scope shall be subject to the claims.

[0059] Example 1

[0060] This embodiment provides a heat-resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0061] 395 parts of solvent DMF, 45 parts of low molecular weight polyether diol PTMG-1000, 40 parts of high molecular weight polyether diol PTMG-3000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 40.8 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0062] The specific steps for preparing the heat-resistant polyurethane resin are as follows:

[0063] S1. Add 70 parts of DMF, 45 parts of low molecular weight polyether diol PTMG-1000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 13.1 parts of MDI, react at 70-80°C for 0.5h, add 40 parts of high molecular weight polyether diol PTMG-3000, continue to react for 0.5h to generate a prepolymer.

[0064] S2, add 6.2 parts of small molecule diol EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27.7 parts of MDI for chain extension reaction, react for 0.5h, add 0.2 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a heat-resistant polyurethane resin.

[0065] Application Example 1

[0066] The heat-aging-resistant polyurethane resin prepared in Example 1 was prepared into sofa leather by the following method:

[0067] According to the mass ratio, 105 parts of heat-resistant polyurethane resin, 50 parts of DMF solvent, 0.3 parts of HQ-818R silicone oil additive, 2 parts of black color paste, 15 parts of wood powder and 7.5 parts of calcium carbonate are mixed and stirred evenly and vacuumed; the vacuumed resin is poured on the 0.35mm Jinfuxiang woven cloth base, and after scraping with a 1.4mm knife head, the cloth base is placed in a mixture of DMF and water with a concentration of 30±2% and coagulated for 10 minutes, and then washed, rolled and dried to obtain sofa leather.

[0068] Example 2

[0069] This embodiment provides a heat-resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0070] 395 parts of solvent DMF, 35 parts of low molecular weight polyether diol PTMG-1000, 50 parts of high molecular weight polyether diol PTMG-3000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 39.2 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0071] The specific steps for preparing the heat-aging resistant polyurethane resin are as follows:

[0072] S1. Add 70 parts of DMF, 35 parts of low molecular weight polyether diol PTMG-1000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 11.6 parts of MDI, react at 70-80°C for 0.5h, add 50 parts of high molecular weight polyether diol PTMG-3000, continue to react for 0.5h to generate a prepolymer.

[0073] S2, add 6.2 parts of EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27.6 parts of MDI for chain extension reaction, react for 0.5h, add 0.2 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a heat-resistant polyurethane resin.

[0074] Application Example 2

[0075] The heat-aging resistant polyurethane resin prepared in Example 2 was used in the same manner as in Application Example 1 to prepare sofa leather.

[0076] Example 3

[0077] This embodiment provides a heat-resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0078] 395 parts of solvent DMF, 25 parts of low molecular weight polyether diol PTMG-1000, 60 parts of high molecular weight polyether diol PTMG-3000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 37.5 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0079] The specific steps for preparing the heat-resistant polyurethane resin are as follows:

[0080] S1. Add 70 parts of DMF, 25 parts of low molecular weight polyether diol PTMG-1000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 10.1 parts of MDI, react at 70-80°C for 0.5h, add 60 parts of high molecular weight polyether diol PTMG-3000, continue to react for 0.5h to generate a prepolymer.

[0081] S2, add 6.2 parts of EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27.4 parts of MDI for chain extension reaction, react for 0.5h, add 0.2 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a heat-resistant polyurethane resin.

[0082] Application Example 3

[0083] The heat-aging resistant polyurethane resin prepared in Example 3 was used in the same manner as in Application Example 1 to prepare sofa leather.

[0084] Example 4

[0085] This embodiment provides a heat-resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0086] 395 parts of solvent DMF, 15 parts of low molecular weight polyether diol PTMG-1000, 70 parts of high molecular weight polyether diol PTMG-3000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 35.8 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0087] The specific steps for preparing the heat-resistant polyurethane resin are as follows:

[0088] S1. Add 70 parts of DMF, 15 parts of low molecular weight polyether diol PTMG-1000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 8.6 parts of MDI, react at 70-80°C for 0.5h, then add 70 parts of high molecular weight polyether diol PTMG-3000, continue to react for 0.5h to generate a prepolymer.

[0089] S2, add 6.2 parts of EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27.2 parts of MDI for chain extension reaction, react for 0.5h, add 0.2 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a heat-resistant polyurethane resin.

[0090] Application Example 4

[0091] The heat-aging resistant polyurethane resin prepared in Example 4 was used in the same manner as in Application Example 1 to prepare sofa leather.

[0092] Example 5

[0093] This embodiment provides a heat-resistant polyurethane resin, which is prepared from the following components in parts by mass:

[0094] 395 parts of solvent DMF, 35 parts of low molecular weight polyether diol PTMG-2000, 50 parts of high molecular weight polyether diol PTMG-4000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 33.75 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0095] The specific steps for preparing the polyether type heat-resistant polyurethane resin are as follows:

[0096] S1. Add 70 parts of DMF, 35 parts of low molecular weight polyether diol PTMG-2000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 6.75 parts of MDI, react at 70-80°C for 0.5h, add 50 parts of high molecular weight polyether diol PTMG-4000, continue to react for 0.5h to generate a prepolymer.

[0097] S2, add 6.2 parts of EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27 parts of MDI for chain extension reaction, react for 0.5h, add 0.2 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a heat-resistant polyurethane resin.

[0098] Application Example 5

[0099] The heat-aging resistant polyurethane resin prepared in Example 5 was used in the same manner as in Application Example 1 to prepare sofa leather.

[0100] Comparative Example

[0101] This comparative example provides a polyurethane resin, which adopts the same implementation as Example 3, except that the high molecular weight polyether diol PTMG-3000 is replaced by an equal mass portion of PTMG-2000. Other components and preparation processes are the same as those in Example 3.

[0102] The polyurethane resin in this comparative example is prepared from the following components in parts by mass:

[0103] 395 parts of solvent DMF, 25 parts of low molecular weight polyether diol PTMG-1000, 60 parts of high molecular weight polyether diol PTMG-2000, 10 parts of polycarbonate diol AS-202, 6.2 parts of small molecular diol EG, 39.9 parts of aromatic diisocyanate MDI, 0.2 parts of catalyst MB20, 0.5 parts of antioxidant Chinox 1010, and 0.5 parts of small molecular monoalcohol MeOH.

[0104] The specific steps for preparing the polyurethane resin are as follows:

[0105] S1. Add 70 parts of DMF, 25 parts of low molecular weight polyether diol PTMG-1000 and 0.5 parts of antioxidant Chinox 1010 into a reaction bottle and stir evenly; then add 12.4 parts of MDI, react at 70-80°C for 0.5h, add 60 parts of high molecular weight polyether diol PTMG-2000, continue to react for 0.5h to generate a prepolymer.

[0106] S2, add 6.2 parts of EG, 10 parts of polycarbonate diol AS-202 and 175 parts of DMF to the prepolymer for dilution, stir evenly, add 27.5 parts of MDI for chain extension reaction, react for 0.5h, add 0.5 parts of MB20 to increase the reaction rate, continue to react for 0.5h, add MDI, when the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After cps / 75°C, the addition of MDI was stopped, the remaining DMF was added for dilution and 0.5 parts of MeOH was added to terminate the reaction to obtain a polyurethane resin.

[0107] Application comparison

[0108] The polyurethane resin prepared in the comparative example was used in the same manner as in Application Example 1 to prepare a sofa leather.

[0109] Performance Testing

[0110] The sofa leather in application examples 1-5 and the comparative example was subjected to peel strength (GB / T 8949) test, including initial peel strength and peel strength after high-temperature embossing process. The high-temperature embossing process is to place the finished leather with the surface pasted on a conveyor with a speed of 10±2m / min, and send the finished leather into an oven at a temperature of 170°C to soften the finished leather. After the finished leather is softened to a degree that is easy to shape, the heated finished leather is placed on a mold with a pattern printed on it, and the finished leather is adsorbed on the mold under a negative pressure of 0.6MPa, so that the finished leather is close to the pattern of the mold and maintained for a period of time. After the finished leather cools down, the negative pressure is released, and the finished product with the formed texture pattern is removed from the mold. See the table below for specific test data:

[0111]

[0112] It can be seen from the above table that the peeling strength of the sofa leather prepared from the heat-resistant polyurethane resin obtained in Examples 1 to 5 after the high-temperature suction pattern embossing process meets the requirements, and there is no problem of peeling strength being lower than the limit.

[0113] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0114] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A heat-resistant polyurethane resin, characterized in that: It is prepared from the following components in parts by mass: 15-45 parts of polyether polyol with a number average molecular weight of 1000-2000, 40-70 parts of polyether polyol with a number average molecular weight of 3000-4000, 5-15 parts of polycarbonate polyol, 5-8 parts of chain extender, 340-430 parts of solvent, 30-50 parts of isocyanate, 0.1-0.5 parts of antioxidant, 0.1-0.5 parts of catalyst and 0.1-0.5 parts of terminator.

2. The heat-resistant polyurethane resin according to claim 1, characterized in that: The polyether polyol is a polyether diol; Preferably, the polyether diol is polytetrahydrofuran diol or polypropylene glycol.

3. The heat-resistant polyurethane resin according to claim 1, characterized in that: The polycarbonate polyol is a polycarbonate diol; Preferably, the number average molecular weight of the polycarbonate diol is 1000-3000.

4. The heat-resistant polyurethane resin according to claim 1, characterized in that: The chain extender is one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, and 3-methyl-1,5-pentanediol; Preferably, the chain extender is ethylene glycol.

5. The heat-aging resistant polyurethane resin according to claim 1, characterized in that: The solvent is one of gamma-butyrolactone, N,N-dimethylformamide, epsilon-caprolactone, dipropylene glycol dimethyl ether, propylene glycol methyl ether acetate, propylene glycol diacetate, and ethylene glycol diacetate.

6. The heat-aging resistant polyurethane resin according to claim 1, characterized in that: The isocyanate is at least one of 4,4'-diphenylmethane diisocyanate, a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

7. The heat-resistant polyurethane resin according to claim 1, characterized in that: The catalyst is a bismuth, zinc or amine catalyst.

8. A method for preparing the heat-aging resistant polyurethane resin according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Add polyether polyol with a number average molecular weight of 1000-2000 and antioxidant to a solvent accounting for 15%-25% of the total solvent, mix well, add isocyanate accounting for 20%-25% of the total isocyanate, react at 70-80° C. for 30-50 minutes, add polyether polyol with a number average molecular weight of 3000-4000, continue to react for 30-50 minutes, and generate a prepolymer; S2, add chain extender, solvent accounting for 35%-45% of the total solvent, and polycarbonate polyol accounting for 8%-12% of the total soft segment to the prepolymer, stir evenly, add isocyanate accounting for 70%-80% of the total isocyanate to carry out chain extension reaction; after reacting for 30-50 minutes, continue to react for 30-50 minutes after adding catalyst, and then continue to add isocyanate. When the solid content reaches 32-38% and the viscosity reaches 8×10 4 -12×10 4 After reaching cps / 75℃, stop adding isocyanate, add the remaining solvent and the terminator to terminate the reaction, and obtain the heat-aging resistant polyurethane resin.

9. Use of the heat-aging-resistant polyurethane resin according to any one of claims 1 to 7 or the heat-aging-resistant polyurethane resin prepared by the preparation method according to claim 8 in the preparation of synthetic leather; Preferably, the synthetic leather is sofa leather.

10. A synthetic leather, characterized in that: Containing the heat-aging resistant polyurethane resin according to any one of claims 1 to 7 or the heat-aging resistant polyurethane resin prepared by the preparation method according to claim 8; Preferably, the synthetic leather is sofa leather.

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