A thermoplastic polyurethane elastomer, a polyurethane foam material, and a preparation method and application thereof

Abstract

The present invention belongs to the technical field of polymer materials, and provides a thermoplastic polyurethane elastomer, a polyurethane foam material, and their preparation methods and applications. The complex viscosity of the thermoplastic polyurethane elastomer is 300 - 100,000 Pa·s at 160 °C and 0.01 Hz; the storage modulus of the thermoplastic polyurethane elastomer at 160 °C and 1 Hz is denoted as G', the loss modulus is denoted as G'', and 0.01 ≤ G' / G'' ≤ 100. Through the design of the complex viscosity and the ratio G' / G'' of the storage modulus to the loss modulus, the present invention enables the material to have excellent foamability. The polyurethane foam material prepared by foaming it has a high foaming ratio, a small density, a uniformly controllable skin thickness, uniform cell sizes, stable cells, a low shrinkage rate, high resilience performance, and excellent mechanical properties, fully meeting the performance requirements of the industry for high-performance foam materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a thermoplastic polyurethane elastomer, a polyurethane foam material, and a preparation method and application thereof. Background Art

[0002] Thermoplastic polyurethane elastomer (TPU) has characteristics such as high tension, high tensile strength, good strength and toughness, aging resistance, and wear resistance. The foaming material prepared with TPU as the matrix has been widely used in the fields of packaging, industry, transportation, daily necessities, medical products, etc. due to its advantages such as light weight, breathability, environmental protection, and good resilience.

[0003] In recent years, the foaming processes of thermoplastic polyurethane foaming materials mainly include bead foaming, sheet foaming, mold foaming, mucell (micro-foaming) injection molding, etc. For example, WO2007082838A1 discloses a foam based on thermoplastic polyurethane, and its preparation method includes: extruding thermoplastic polyurethane with a Shore hardness of A44 - A84 to obtain particles with an average diameter of 0.2 - 10 mm, impregnating the particles with a blowing agent based on 0.1 - 40% by weight of the total weight of the particles in an aqueous suspension under pressure and at 100 - 150 °C, and then cooling the suspension of thermoplastic polyurethane containing the blowing agent to 20 - 95 °C and decompressing to obtain a polyurethane foam. CN102229709A discloses an environmentally friendly polyurethane foaming profile, which is directly prepared by a physical gas foaming method using a polyurethane raw material containing a modifier in the presence of a physical gas blowing agent, with a foaming density of 0.08 - 0.80 g / cm 3 , an average pore diameter of 10 - 100 μm, uniform cell structure, and no skin layer structure. However, currently, the density of polyurethane foaming products is relatively high and the resilience is poor, generally about 50 - 55%; moreover, as a crystalline polymer, TPU has a sudden drop in viscosity near the melting point, with too low viscosity, resulting in larger pore diameters in the foaming products, and at the same time, the probability of pore rupture increases and the skin thickness is uneven, which leads to poor resilience and low bending stiffness of the product, making it difficult to meet the requirements of professional functional sports shoes.

[0004] The supercritical fluid foaming technology uses supercritical CO2, N2 and other inert gases as foaming agents. Compared with traditional physical foaming agents such as alkanes and Freons, supercritical fluid foaming agents have the advantages of wide sources, environmental friendliness, and non-flammability. However, there are serious shrinkage problems in the polyurethane particles after foaming with supercritical CO2. This serious shrinkage not only significantly increases the density of the foamed material, but also causes obvious wrinkles and depressions on the surface of the foamed material, uneven skin formation, which seriously affects the subsequent use of the foamed material. The commonly used method now is to improve the shrinkage problem by blending other polymers, size stabilizers or nucleating agents, etc. For example, CN103709726A discloses an extruded foamed thermoplastic polyurethane elastomer bead, which contains 100 parts by weight of thermoplastic polyurethane elastomer, 0.01-0.5 parts by weight of foaming nucleating agent, 0.01-0.2 parts by weight of antioxidant, and the foaming process uses supercritical fluid, and the addition amount is 1-40 parts by weight; the foaming nucleating agent is talc, silica, calcium carbonate, zeolite, graphite, alumina, calcium hydroxide, aluminum hydroxide, zinc borate, etc.; by adding the foaming nucleating agent, the particle density is reduced and the cell structure is uniform, but such a method will not only increase the cost, but also reduce the foaming ratio, and cannot effectively solve the problem of uneven skin formation.

[0005] Therefore, it is an urgent problem to be solved in this field to develop a thermoplastic polyurethane foamed material with uniform and controllable skin thickness, high foaming ratio and good resilience. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a thermoplastic polyurethane elastomer, a polyurethane foam material and its preparation method and application. Through the design of the complex viscosity, the ratio of the storage modulus to the loss modulus, the thermoplastic polyurethane elastomer has excellent foamability, and the polyurethane foam material obtained by its foaming has a high foaming ratio, low density, uniform and controllable skin thickness, excellent resilience and mechanical properties.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a thermoplastic polyurethane elastomer, the complex viscosity of the thermoplastic polyurethane elastomer at 160 °C and 0.01 Hz is 300-100000 Pa·s; the storage modulus of the thermoplastic polyurethane elastomer at 160 °C and 1 Hz is denoted as G', and the loss modulus is denoted as G'', and 0.01 ≤ G' / G'' ≤ 100.

[0009] The thermoplastic polyurethane elastomer provided by the present invention has a specific complex viscosity and a ratio G' / G'' of storage modulus to loss modulus. Through parameter design, it has excellent foamability. The polyurethane foam material obtained by foaming the thermoplastic polyurethane elastomer has a high foaming ratio, low density, a uniformly controllable skin thickness, uniform and stable cell sizes, a low shrinkage rate, and high resilience and excellent mechanical properties.

[0010] The following are the preferred technical solutions of the present invention, but they do not 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.

[0011] In the present invention, the complex viscosity, storage modulus (G'), and loss modulus (G'') of the thermoplastic polyurethane elastomer can be obtained by testing with a rotational rheometer.

[0012] Exemplarily, the method of testing with a rotational rheometer is as follows: Use an instrument of model MCR 102e produced by Anton Paar GmbH. In the range of 120 - 180 °C, the test frequency is set to 0.0001 - 200 Hz. Cut the test piece into a circular piece with a diameter of 15 - 25 mm and a thickness of 0.01 - 5 mm for frequency scanning. Take the complex viscosity at 160 °C and 0.01 Hz, and take the storage modulus G' and loss modulus G'' at 160 °C and 1 Hz.

[0013] In the present invention, the complex viscosity of the thermoplastic polyurethane elastomer at 160 °C and 0.01 Hz is 300 - 100000 Pa·s. For example, it can be 400 Pa·s, 500 Pa·s, 1000 Pa·s, 2000 Pa·s, 5000 Pa·s, 8000 Pa·s, 10000 Pa·s, 12000 Pa·s, 15000 Pa·s, 18000 Pa·s, 20000 Pa·s, 25000 Pa·s, 30000 Pa·s, 35000 Pa·s, 40000 Pa·s, 45000 Pa·s, 50000 Pa·s, 55000 Pa·s, 60000 Pa·s, 65000 Pa·s, 70000 Pa·s, 75000 Pa·s, 80000 Pa·s, 85000 Pa·s, 90000 Pa·s, or 95000 Pa·s, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the above range. Preferably, it is 300 - 80000 Pa·s, and more preferably 300 - 50000 Pa·s.

[0014] The complex viscosity of the thermoplastic polyurethane elastomer described in the present invention is 300-100,000 Pa·s at 160°C and 0.01 Hz, and it can produce polyurethane foam materials with high expansion ratio and high stability. If the complex viscosity of the thermoplastic polyurethane elastomer is lower than 300 Pa·s, the stability of the prepared polyurethane foam product will be severely lost and the foam cells are likely to rupture; if the complex viscosity of the thermoplastic polyurethane elastomer is higher than 100,000 Pa·s, the processing pressure required during foaming and product forming is relatively high, and it is difficult to obtain a polyurethane foam product with a high expansion ratio.

[0015] In the present invention, the storage modulus of the thermoplastic polyurethane elastomer at 160°C and 1 Hz is denoted as G', the loss modulus is denoted as G'', 0.01 ≤ G' / G'' ≤ 100, G' / G'' can be 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 5, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 or 95, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range. Preferably, 0.01 ≤ G' / G'' ≤ 10, and more preferably 0.01 ≤ G' / G'' ≤ 1.

[0016] The ratio of the storage modulus to the loss modulus of the thermoplastic polyurethane elastomer of the present invention at 160°C and 1 Hz is 0.01-100, and it can be foamed to obtain a polyurethane foam material with a high expansion ratio, low density, uniform and controllable skin thickness, low shrinkage rate, excellent resilience and mechanical properties. If G' / G'' < 0.01, the expansion ratio of the polyurethane foam material will be significantly reduced, the shrinkage rate will be high, and the resilience will decrease; if G' / G'' > 100, the skin thickness of the foamed material will be uneven and obvious shrinkage problems will occur.

[0017] Preferably, the thermoplastic polyurethane elastomer is obtained by the reaction of an isocyanate, a polyol and optionally a chain extender.

[0018] Preferably, the thermoplastic polyurethane elastomer is obtained by the reaction of an isocyanate, a polyol and a chain extender; wherein the isocyanate and the chain extender participate in constructing the hard segment structure of the thermoplastic polyurethane elastomer, and the polyol constructs the soft segment structure of the thermoplastic polyurethane elastomer.

[0019] Preferably, the isocyanate includes any one or a combination of at least two of aliphatic isocyanates, cycloaliphatic isocyanates, and aromatic isocyanates, and further preferably aliphatic isocyanates and / or cycloaliphatic isocyanates.

[0020] Preferably, the isocyanate includes any one or a combination of at least two of hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate. Further preferably, it is hexamethylene diisocyanate and / or dicyclohexylmethane diisocyanate.

[0021] Preferably, the polyol includes any one or a combination of at least two of polycarboxylate polyol, polyether polyol, polycarbonate polyol, and polycaprolactone polyol.

[0022] Preferably, the polyol includes any one or a combination of at least two of butylene adipate, polytetramethylene ether glycol, butylene glycol / ethylene glycol adipate, polycarbonate polyol, polycaprolactone polyol, ethylene glycol adipate, hexanediol adipate, hexanediol / ethylene glycol adipate, and hexanediol / butylene glycol adipate.

[0023] Preferably, the number average molecular weight (M n ) of the polyol is 500 - 3500 g / mol. For example, it can be 600 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, 3200 g / mol, or 3400 g / mol, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the specific point values included in the scope of the present invention are not exhaustively listed herein. Further preferably, it is 800 - 2500 g / mol.

[0024] Preferably, the chain extender is a small molecule compound containing at least 2 (≥2, such as 2, 3, 4, etc., further preferably 2) active hydrogen groups, and the active hydrogen groups include hydroxyl and / or amino groups.

[0025] Preferably, the chain extender includes small molecule diols and / or small molecule diamines.

[0026] Preferably, the chain extender includes any one or a combination of at least two of ethylene glycol, propylene glycol, butylene glycol, hexanediol, cyclohexanedimethanol, dihydroxyethyl ether of hydroquinone, propylenediamine, butylenediamine, p-phenylenediamine, benzidine, and 3,3'-dimethyl-4,4'-biphenylenediamine.

[0027] Further preferably, the chain extender includes any one or a combination of at least two of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, cyclohexanedimethanol, hydroquinone dihydroxyethyl ether, 1,3-propanediamine, 1,4-butanediamine, p-phenylenediamine, benzidine, 3,3'-dimethyl-4,4-biphenylenediamine.

[0028] Preferably, the Shore hardness of the thermoplastic polyurethane elastomer is 60 A - 70 D. For example, it can be 62 A, 65 A, 68 A, 70 A, 72 A, 75 A, 78 A, 80 A, 82 A, 85 A, 88 A, 90 A, 92 A, 95 A, 98 A, 100 A, 62 D, 65 D or 68 D, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is 80 A - 55 D, more preferably 85 A - 100 A, and particularly preferably 85 A - 95 A.

[0029] Exemplarily, the Shore hardness of the thermoplastic polyurethane elastomer is obtained by the method in ASTM D2240-05.

[0030] Preferably, the tensile strength of the thermoplastic polyurethane elastomer is ≥20 MPa. For example, it can be 21 MPa, 22 MPa, 25 MPa, 28 MPa, 30 MPa, 32 MPa, 35 MPa, 38 MPa, 40 MPa or 45 MPa, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is 22 - 40 MPa.

[0031] Preferably, the elongation at break of the thermoplastic polyurethane elastomer is 400% - 750%. For example, it can be 420%, 450%, 480%, 500%, 520%, 550%, 580%, 600%, 620%, 650%, 680%, 700%, 720% or 740%, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0032] Exemplarily, the tensile strength and elongation at break of the thermoplastic polyurethane elastomer are obtained by the method in ASTM D412.

[0033] Exemplarily, the preparation method of the thermoplastic polyurethane elastomer includes: carrying out a polymerization reaction on an isocyanate, a polyol and a chain extender to obtain the thermoplastic polyurethane elastomer.

[0034] Preferably, the molar amount of the NCO groups in the isocyanate is denoted as n1, and the total molar amount of the active hydrogen groups in the polyol and the chain extender is denoted as n2. The ratio of n1:n2 is 1:(0.9 - 1.1), and for example, it can be 1:0.91, 1:0.92, 1:0.93, 1:0.94, 1:0.95, 1:0.96, 1:0.97, 1:0.98, 1:0.99, 1:0.992, 1:0.995, 1:0.998, 1:1, 1:1.012, 1:1.015, 1:1.018, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09, etc. Further preferably, it is 1:(0.99 - 1.1).

[0035] Among them, the total molar amount of the active hydrogen groups in the polyol and the chain extender represents the total molar amount of hydroxyl groups and amino groups (if any); when the chain extender is a small molecule diol, the total molar amount of the active hydrogen groups in the polyol and the chain extender is the total molar amount of hydroxyl groups; when the chain extender includes a small molecule diamine, the total molar amount of the active hydrogen groups in the polyol and the chain extender is the total molar amount of hydroxyl groups and amino groups.

[0036] Preferably, based on the total mass of the isocyanate, polyol and chain extender being 100%, the mass of the isocyanate is 12% - 35%, for example, it can be 13%, 14%, 15%, 16%, 18%, 20%, 22%, 25%, 28%, 30%, 32% or 34%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range. Further preferably, it is 15% - 30%.

[0037] Preferably, based on the total mass of the isocyanate, polyol and chain extender being 100%, the mass of the chain extender is 0.7% - 25%, for example, it can be 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23% or 24%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0038] Preferably, the polymerization reaction is carried out in the presence of a catalyst.

[0039] In the present invention, the type of the catalyst is not specifically limited, and any catalyst known in the art that can catalyze the reaction of active hydrogen with NCO groups to form urethane groups is applicable to the present invention.

[0040] Preferably, the catalyst includes any one or a combination of at least two of organotin catalysts, amine catalysts, and organobismuth catalysts, and further preferably any one or a combination of at least two of dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, and triethylamine.

[0041] Preferably, based on the mass of the polyol being 100%, the mass of the catalyst is 0.001% - 0.5%, for example, it can be 0.002%, 0.005%, 0.008%, 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, or 0.45%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0042] Preferably, the polymerization reaction is carried out in the presence of an antioxidant.

[0043] Preferably, the antioxidant includes any one or a combination of at least two of hindered amine antioxidants, hindered phenol antioxidants, and phosphite antioxidants.

[0044] Preferably, based on the mass of the polyol being 100%, the mass of the antioxidant ≤ 1%, for example, it can be 0, 0.002%, 0.005%, 0.008%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, 0.7%, 0.8%, or 0.9%, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range, and further preferably 0 - 0.8%.

[0045] Preferably, the polymerization reaction is carried out in an extruder.

[0046] Preferably, the extruder includes a screw extruder, and further preferably a twin - screw extruder.

[0047] Preferably, the method for preparing the thermoplastic polyurethane elastomer includes: uniformly mixing isocyanate, polyol, chain extender, and optionally an antioxidant to obtain a mixture; injecting the mixture into a screw extruder for polymerization reaction, and then extruding, cooling, and pelletizing to obtain the thermoplastic polyurethane elastomer (pellets).

[0048] Preferably, the temperature of the screw extruder is 100 - 220 °C, for example, it can be 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C or 210 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0049] Preferably, the screw rotation speed of the screw extruder is 100 - 300 rpm, for example, it can be 120 rpm, 150 rpm, 180 rpm, 200 rpm, 220 rpm, 250 rpm or 280 rpm, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the range.

[0050] Preferably, the pellets obtained by granulation are cooled to ≤35 °C (such as 18 °C, 20 °C, 22 °C, 25 °C, 28 °C, 30 °C, 32 °C, 34 °C, etc.) for packaging and storage.

[0051] In a second aspect, the present invention provides a polyurethane foam material, which is obtained by foaming a thermoplastic polyurethane elastomer as described in the first aspect.

[0052] Preferably, the foaming method includes the supercritical fluid foaming method.

[0053] In a third aspect, the present invention provides a preparation method of the polyurethane foam material as described in the second aspect, and the preparation method includes the following steps:

[0054] Using a physical foaming agent to foam the thermoplastic polyurethane elastomer as described in the first aspect under pressure conditions; after the foaming is completed, depressurize and cure to obtain the polyurethane foam material;

[0055] The foaming includes the first-stage foaming and the second-stage foaming carried out in sequence. The temperature of the first-stage foaming is denoted as T1, and the temperature of the second-stage foaming is denoted as T2, 5 °C ≤ T2 - T1 ≤ 20 °C;

[0056] The curing temperature is denoted as T3, 0 ≤ T3 - T1 ≤ 20 °C.

[0057] The polyurethane foam material of the present invention is obtained by foaming the thermoplastic polyurethane elastomer provided in the first aspect. On the basis of using a specific thermoplastic polyurethane elastomer, the preparation method further designs a two-stage foaming process. Through the process control of temperature, depressurization and curing during the foaming process, a polyurethane foam material with high foaming ratio, low density, uniform and controllable skin thickness, uniform cell structure, low shrinkage, excellent resilience and mechanical properties can be obtained.

[0058] In the present invention, the temperature T2 of the second-stage foaming > the temperature T1 of the first-stage foaming, and T2 - T1 is 5 - 20°C. For example, it can be 6°C, 8°C, 10°C, 12°C, 14°C, 15°C, 16°C or 18°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0059] In the present invention, after depressurization, curing is also carried out. The temperature T3 of the curing ≥ the temperature T1 of the first-stage foaming, and T3 - T1 is 0 - 20°C. For example, it can be 1°C, 2°C, 4°C, 5°C, 6°C, 8°C, 10°C, 12°C, 14°C, 15°C, 16°C or 18°C, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the above range.

[0060] Preferably, the physical blowing agent includes any one or a combination of at least two of nitrogen, carbon dioxide, methane, propane, butane, and pentane.

[0061] Preferably, the foaming method includes the supercritical fluid foaming method.

[0062] Preferably, the physical blowing agent includes nitrogen and / or carbon dioxide, more preferably supercritical nitrogen and / or supercritical carbon dioxide, and further preferably critical carbon dioxide or a combination of supercritical carbon dioxide and supercritical nitrogen.

[0063] It should be noted that the material form of the thermoplastic polyurethane elastomer is not limited. For example, it can be beads, sheets or plates; the foaming form can be bead foaming, plate foaming, mold foaming, injection foaming, etc.

[0064] In a preferred technical solution, the material form of the thermoplastic polyurethane elastomer is beads, and the preparation method includes: mixing the beads, the physical blowing agent and the solvent to obtain a suspension; the suspension is foamed under pressure conditions, and after the foaming is completed, depressurization and curing are carried out to obtain the polyurethane foam material (in bead form).

[0065] Preferably, the solvent includes water.

[0066] Preferably, the mass ratio of the solvent to the beads is (0.5 - 5):1. For example, it can be 0.6:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc.

[0067] In another preferred technical solution, the material form of the thermoplastic polyurethane elastomer is a sheet or a plate, and the preparation method includes: placing the sheet or plate in a foaming device, filling it with a physical foaming agent, and then foaming it under pressure conditions. After the foaming is completed, the pressure is released and the material is cured to obtain the polyurethane foam material (sheet or plate).

[0068] Preferably, the pressure for foaming is 10 - 65 MPa. For example, it can be 15 MPa, 18 MPa, 20 MPa, 22 MPa, 25 MPa, 28 MPa, 30 MPa, 32 MPa, 35 MPa, 38 MPa, 40 MPa, 42 MPa, 45 MPa, 48 MPa, 50 MPa, 52 MPa, 55 MPa or 58 MPa, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list all the specific point values included in the above range.

[0069] Preferably, the temperature for the first - stage foaming is 100 - 160°C. For example, it can be 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C or 155°C, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list all the specific point values included in the above range.

[0070] Preferably, the time for the first - stage foaming is 0.1 - 24 h. For example, it can be 0.2 h, 0.5 h, 1 h, 2 h, 4 h, 5 h, 6 h, 8 h, 10 h, 12 h, 14 h, 15 h, 16 h, 18 h, 20 h, 22 h or 23 h, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list all the specific point values included in the above range. Further preferably, it is 0.5 - 10 h.

[0071] Preferably, the temperature for the second - stage foaming is 105 - 180°C. For example, it can be 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C or 175°C, as well as specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list all the specific point values included in the above range.

[0072] Preferably, the time for the second-stage foaming is 0.05 - 5 h, for example, it can be 0.1 h, 0.2 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h or 4.5 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the scope. Further preferably, it is 0.1 - 5 h.

[0073] In the present invention, the "pressure relief" means releasing pressure.

[0074] Preferably, the curing temperature is 100 - 180 °C, for example, it can be 105 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, 150 °C, 155 °C, 160 °C, 165 °C, 170 °C or 175 °C, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the scope.

[0075] Preferably, the curing time is 0.1 - 24 h, for example, it can be 0.2 h, 0.5 h, 1 h, 2 h, 4 h, 5 h, 6 h, 8 h, 10 h, 12 h, 14 h, 15 h, 16 h, 18 h, 20 h, 22 h or 23 h, as well as the specific point values between the above point values. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the scope. Further preferably, it is 0.1 - 5 h.

[0076] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0077] Mixing the beads of thermoplastic polyurethane elastomer, physical foaming agent and solvent to obtain a suspension; the suspension is successively subjected to the first-stage foaming and the second-stage foaming under a pressure condition of 10 - 65 MPa; the temperature of the first-stage foaming is 100 - 160 °C and the time is 0.1 - 24 h; the temperature of the second-stage foaming is 105 - 180 °C and the time is 0.05 - 5 h;

[0078] After the foaming is completed, the pressure is relieved, and then it is cured at 100 - 180 °C for 0.1 - 5 h to obtain the polyurethane foam material (foamed beads).

[0079] Optionally, the polyurethane foam material (foamed beads) is placed in a mold and formed under heat treatment conditions to obtain a formed product (such as a plate).

[0080] Preferably, the heat treatment is heat treatment molding using steam.

[0081] Preferably, the pressure of the water vapor is 0.8 - 2.5 bar, for example, it can be 1 bar, 1.2 bar, 1.5 bar, 1.8 bar, 2 bar, 2.2 bar or 2.4 bar, as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0082] As another preferred technical solution of the present invention, the preparation method includes the following steps:

[0083] Place the sheet-like or plate-like thermoplastic polyurethane elastomer in a foaming device. After filling with a physical foaming agent, carry out the first-stage foaming and the second-stage foaming in sequence under a pressure condition of 10 - 65 MPa; the temperature of the first-stage foaming is 100 - 160 °C, and the time is 0.1 - 24 h; the temperature of the second-stage foaming is 105 - 180 °C, and the time is 0.05 - 5 h;

[0084] After the foaming is completed, release the pressure, and then cure at 100 - 180 °C for 0.1 - 5 h to obtain the polyurethane foam material (foamed sheet or foamed board).

[0085] Preferably, the density of the polyurethane foam material is 0.03 - 0.2 g / cm 3 , for example, it can be 0.04 g / cm 3 , 0.05 g / cm 3 , 0.06 g / cm 3 , 0.08 g / cm 3 , 0.1 g / cm 3 , 0.12 g / cm 3 , 0.15 g / cm 3 or 0.18 g / cm 3 , as well as the specific point values between the above point values. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0086] Preferably, the shrinkage rate of the polyurethane foam material is ≤2%, preferably ≤1.6%, more preferably ≤1.5%, and can be 0.8 - 1.5%.

[0087] Preferably, the ball-drop rebound rate of the polyurethane foam material is >70%, more preferably ≥75%, and can be 75% - 82%.

[0088] Preferably, the skin thickness of the polyurethane foam material is ≤100 μm, and can be, for example, 15 μm, 20 μm, 30 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 70 μm, 80 μm or 90 μm, preferably 20 - 100 μm, more preferably 20 - 40μm.

[0089] In a fourth aspect, the present invention provides an application of the polyurethane foam material as described in the second aspect in shoe materials, seat materials, tires, decorative materials, cushioning materials, thermal insulation materials, sound insulation materials, toys or sports equipment.

[0090] Preferably, the polyurethane foam material is applied to shoe soles, tires, bicycle seats, interior decorations, cushion pads, sound insulation pads or children's toys.

[0091] Compared with the prior art, the present invention has the following beneficial effects:

[0092] In the thermoplastic polyurethane elastomer provided by the present invention, through the design of the complex viscosity and the ratio G' / G'' of the storage modulus to the loss modulus, it has excellent foamability. The polyurethane foam material prepared by foaming the thermoplastic polyurethane elastomer has a high foaming ratio, a small density, a uniform and controllable skin thickness, uniform cell sizes, stable cells, a low shrinkage rate, high resilience performance and excellent mechanical properties, fully meeting the performance requirements of the industry for high-performance foam materials. Detailed Embodiments

[0093] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0094] As used herein, the terms "comprising", "including", "having", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the recited elements is not necessarily limited to those elements, but may also include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0095] "Optionally", "alternatively" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes the case where the event occurs and the case where the event does not occur.

[0096] In the following specific embodiments of the present invention, the materials for which the preparation methods are not provided are all commercially available chemicals, and the specific information of the materials is as follows:

[0097]

[0098] In the following specific embodiments of the present invention, the main testing methods for thermoplastic polyurethane elastomers and polyurethane foam materials are as follows:

[0099] (1) Complex viscosity

[0100] A circular sheet with a diameter of 20 mm and a thickness of 1 mm is made from the thermoplastic polyurethane elastomer to be tested. Using an instrument model MCR 102e produced by Anton Paar GmbH, in the temperature range of 120 - 180 °C, the test frequency is set to 0.0001 - 200 Hz, and the complex viscosity at 160 °C and 0.01 Hz is recorded.

[0101] (2) Storage modulus G' and loss modulus G''

[0102] A circular sheet with a diameter of 20 mm and a thickness of 1 mm is made from the thermoplastic polyurethane elastomer to be tested. Using an instrument model MCR 102e produced by Anton Paar GmbH, in the temperature range of 120 - 180 °C, the test frequency is set to 0.0001 - 200 Hz, and the storage modulus G' and loss modulus G'' at 160 °C and 1 Hz are recorded, and G' / G'' is calculated.

[0103] (3) Hardness

[0104] An injection - molded 2 - mm specimen is tested according to the method in Standard ASTM D2240 - 05 to obtain the shore A hardness.

[0105] (4) Tensile strength and elongation at break

[0106] An injection - molded 2 - mm specimen is tested according to the method in Standard ASTM D412.

[0107] (4) Density

[0108] It is tested according to the method in Standard ASTM D792.

[0109] (5) Ball rebound

[0110] It is tested according to the method in Standard ISO 8307 - 2007.

[0111] (6) Shrinkage rate

[0112] It is tested according to the methods in Standards ISO 294 - 4 and 2577.

[0113] (7) Skin thickness

[0114] Cut the polyurethane foam material (particles or sheets) to be tested into thin slices, observe the uniformity of the cell structure under an optical microscope, and measure the cell diameter and skin thickness. The skin thickness of the foam material refers to the thickness from the outer skin to the cells observed under an optical microscope. The optical microscope used is the Patriot Digital Observation King GE-5, and its software has a built-in image measurement function.

[0115] The following will take multiple embodiments as examples to elaborate on the thermoplastic polyurethane elastomer, polyurethane foam material, and their preparation methods described in the present invention. However, the thermoplastic polyurethane elastomer, polyurethane foam material, and their preparation methods described in the present invention are not limited to these embodiments.

[0116] In the following embodiments, carbon dioxide and nitrogen, which are used as physical blowing agents, are both supercritical fluids.

[0117] Example 1

[0118] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PBA-1000, 0.408 parts of HDI, 0.131 parts of 1,4-butanediol, 0.0001 parts of stannous octoate, and 0.005 parts of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; the mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer; the temperatures of the 1st - 10th zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, and the screw speed is 190 rpm; the obtained thermoplastic polyurethane elastomer is cooled and pelletized to obtain thermoplastic polyurethane elastomer (TPU) pellets, the pellets are cooled to 25°C and stored, and injection molding is performed on them to make 2 mm test pieces, and the test results are shown in Table 1.

[0119] A polyurethane foam material and its preparation method are as follows: Using the TPU pellets provided in this example, 1 kg of the TPU pellets and 1 kg of water are added to a 20 L high-pressure reactor, filled with 15 MPa of carbon dioxide to form a suspension, then heated to 140°C, maintained at a pressure of 15 MPa, and foamed at a constant temperature for 2 h, then heated to 150°C and foamed for 10 min; then the gas in the pressure vessel is discharged into the atmospheric environment, and cured at a constant temperature of 150°C for 1 h, and dried to obtain TPU foam pellets; the above-obtained TPU foam pellets are filled into a mold with a length of 300 mm × width of 200 mm × thickness of 40 mm, and compressed by 15% along the thickness direction of the mold with 1.2 bar of steam pressure to bond the particles into a shape, and finally a molded foam product is obtained, and then placed at room temperature for 48 h for performance evaluation, and the data is shown in Table 1.

[0120] Example 2

[0121] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PTMEG-1000, 0.337 part of HDI, 0.092 part of 1,4-butanediol, 0.0003 part of triethylamine, and 0.005 part of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; The mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2 mm test piece is injection-molded from it, and the test results are shown in Table 1.

[0122] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are extruded into a 15 mm thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, heated to 115°C, and the pressure is maintained at 20 MPa for isothermal and isobaric foaming for 1 h, and then heated to 130°C for foaming for 15 min; Then the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and it is cured isothermally at 130°C for 0.5 h to obtain a TPU foam plate, and its performance evaluation data is shown in Table 1.

[0123] Example 3

[0124] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PEBA-2000, 0.223 part of HDI, 0.075 part of 1,6-hexanediol, 0.0005 part of stannous octoate, and 0.005 part of antioxidant 1024 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; The mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 25°C to obtain TPU beads. A 2 mm test piece is injection-molded from it, and the test results are shown in Table 1.

[0125] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are injection molded into small embryos of the shoe midsole, and then placed in a foaming kettle for foaming. 10 MPa of carbon dioxide and 15 MPa of nitrogen are filled, and then the temperature is raised to 145 °C, and the pressure is maintained at 25 MPa. Foaming is carried out at a constant temperature and pressure for 3 h, and then the temperature is raised to 160 °C for foaming for 15 min; then the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and aging is carried out at a constant temperature of 160 °C for 4 h to obtain a large embryo of the foam shoe material, and the performance evaluation data are shown in Table 1.

[0126] Example 4

[0127] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PCL-1000, 0.494 parts of HDI, 0.174 parts of 1,4-butanediol, 0.0006 parts of stannous octoate, and 0.005 parts by weight of antioxidant 168 are transported to the pouring system through a gear pump and mixed evenly to obtain a mixture; The mixture is poured onto a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are: 120 °C, 150 °C, 155 °C, 160 °C, 160 °C, 190 °C, 190 °C, 190 °C, 210 °C, 210 °C, the head temperature is 210 °C, the screw speed is 190 rpm, and the obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30 °C to obtain TPU beads. An injection molded 2 mm specimen is made of it, and the test results are shown in Table 1.

[0128] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are injection molded into a plate, and the plate is placed in a foaming kettle. 5 MPa of carbon dioxide and 15 MPa of nitrogen are filled, and the temperature is raised to 150 °C while maintaining a constant temperature, and the pressure is maintained at 20 MPa. Foaming is carried out at a constant temperature and pressure for 3 h, and then the temperature is raised to 165 °C for foaming for 15 min; then the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and aging is carried out at a constant temperature of 165 °C for 1 h to obtain an injection molded TPU foam plate, and the performance evaluation data are shown in Table 1.

[0129] Example 5

[0130] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PCDL-1500, 0.318 part of HDI, 0.111 part of 1,4-butanediol, 0.0003 part of triethylamine, and 0.005 part of antioxidant 1010 are conveyed through a gear pump to a casting system and mixed evenly to obtain a mixture; The mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1st to 10th zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, and the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2-mm injection-molded specimen is made from it, and the test results are shown in Table 1.

[0131] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are processed through a screw extruder to obtain a 10-mm thick plate. The plate is placed in a foaming kettle, filled with 7 MPa of carbon dioxide and 18 MPa of nitrogen, then heated to 145°C, and foamed at a constant temperature and pressure of 25 MPa for 3 h, and then heated to 160°C for foaming for 15 min; Then, the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and cured at a constant temperature of 160°C for 0.1 h to obtain a TPU foam plate, and its performance evaluation data are shown in Table 1.

[0132] Example 6

[0133] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PCDL-1500, 0.364 part of HMDI, 0.065 part of 1,4-butanediol, 0.003 part of triethylamine, and 0.005 part of antioxidant 1010 are conveyed through a gear pump to a casting system and mixed evenly to obtain a mixture; The mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1st to 10th zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, and the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2-mm injection-molded specimen is made from it, and the test results are shown in Table 1.

[0134] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are processed through a screw extruder to obtain a 10-mm-thick plate. The plate is placed in a foaming kettle, filled with 7 MPa of carbon dioxide and 18 MPa of nitrogen, then heated to 145°C, and foamed at a constant temperature and pressure of 25 MPa for 3 h, and then heated to 160°C for foaming for 15 min; then the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and cured at a constant temperature of 160°C for 0.1 h to obtain a TPU foam plate, and the performance evaluation data are shown in Table 1.

[0135] Example 7

[0136] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PCDL-1500, 0.297 parts of HDI, 0.131 parts of 1,4-hexanediol, 0.0003 parts of triethylamine, and 0.005 parts of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; the mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures in zones 1-10 of the twin-screw extruder are 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C respectively, the head temperature is 210°C, the screw speed is 190 rpm, the obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads, and 2-mm test pieces are injection-molded from them, and the test results are shown in Table 1.

[0137] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are processed through a screw extruder to obtain a 10-mm-thick plate. The plate is placed in a foaming kettle, filled with 7 MPa of carbon dioxide and 18 MPa of nitrogen, then heated to 145°C, and foamed at a constant temperature and pressure of 25 MPa for 3 h, and then heated to 160°C for foaming for 15 min; then the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and cured at a constant temperature of 160°C for 0.1 h to obtain a TPU foam plate, and the performance evaluation data are shown in Table 1.

[0138] Example 8

[0139] A thermoplastic polyurethane elastomer and its preparation method have the same materials and preparation processes as those in Example 2.

[0140] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are extruded into a 15-mm-thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, heated to 115 °C, and the pressure is maintained at 20 MPa for isothermal and isobaric foaming for 75 min. Then, the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and it is cured at a constant temperature of 145 °C for 0.5 h to obtain a TPU foam plate. The performance evaluation data are shown in Table 1.

[0141] Example 9

[0142] A thermoplastic polyurethane elastomer and its preparation method have the same materials and preparation process as those in Example 2.

[0143] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are extruded into a 15-mm-thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, heated to 130 °C, and the pressure is maintained at 20 MPa for isothermal and isobaric foaming for 75 min. Then, the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and it is cured at a constant temperature of 145 °C for 0.5 h to obtain a TPU foam plate. The performance evaluation data are shown in Table 1.

[0144] Example 10

[0145] A thermoplastic polyurethane elastomer and its preparation method have the same materials and preparation process as those in Example 2.

[0146] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this example are extruded into a 15-mm-thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, heated to 115 °C, and the pressure is maintained at 20 MPa for isothermal and isobaric foaming for 1 h, and then heated to 130 °C for foaming for 15 min. Then, the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment, and it is cooled to obtain a TPU foam plate. The performance evaluation data are shown in Table 1.

[0147] Comparative Example 1A

[0148] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PBA-1000, 0.15 part of HDI, 0.008 part of 1,4-butanediol, 0.0006 part of stannous octoate, and 0.005 part of antioxidant 1010 are transported through a gear pump to a casting system and mixed evenly to obtain a mixture; the mixture is cast onto a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized to obtain thermoplastic polyurethane elastomer (TPU) pellets, and the pellets are cooled to 25°C for storage. They are injection-molded into 2 mm test pieces, and the test results are shown in Table 1.

[0149] A polyurethane foam material and its preparation method are as follows: Using the TPU pellets provided in this comparative example, 1 kg of the TPU pellets and 1 kg of water are added to a 20 L high-pressure reactor, filled with 15 MPa of carbon dioxide to form a suspension, and then heated to 110°C, maintaining the pressure at 15 MPa for foaming for 3 h; then the gas in the pressure vessel is discharged into the atmospheric environment, and dried to obtain TPU foam pellets; the above-obtained TPU foam pellets are filled into a mold with a length of 300 mm × width of 200 mm × thickness of 40 mm, and compressed by 15% along the thickness direction of the mold with 1.2 bar of steam pressure to bond the particles into a shape, and finally a molded foam product is obtained. Then it is placed at room temperature for 48 h for performance evaluation, and the data are shown in Table 1.

[0150] Comparative Example 1B

[0151] A polyurethane foam material and its preparation method are as follows: Using the TPU pellets provided in Comparative Example 1A, a polyurethane foam material is prepared by the same method as in Example 2, and the performance evaluation data are shown in Table 1.

[0152] Comparative Example 2A

[0153] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PCDL-1500, 0.833 parts of HDI, 0.388 parts of 1,4-butanediol, 0.0001 parts of triethylamine, and 0.005 parts of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; The mixture is poured onto a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2 mm test piece is injection-molded from it, and the test results are shown in Table 2.

[0154] A polyurethane foam material and its preparation method are as follows: The TPU beads provided in this comparative example are extruded into a 10 mm thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, and then heated to 145°C and kept at a pressure of 20 MPa for foaming for 3 h. The carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment to obtain a foamed TPU plate, and its performance evaluation data are shown in Table 1.

[0155] Comparative Example 2B

[0156] A polyurethane foam material and its preparation method are as follows: Using the TPU beads provided in Comparative Example 2A, a polyurethane foam material is prepared by the same method as in Example 5, and its performance evaluation data are shown in Table 1.

[0157] Comparative Example 3A

[0158] A thermoplastic polyurethane elastomer and its preparation method are as follows: By mass, 1 part of PTMEG-1000, 0.274 parts of HDI, 0.059 parts of 1,4-butanediol, 0.0001 parts of triethylamine, and 0.005 parts of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture; The mixture is poured onto a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1-10 zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 210°C, 210°C, the head temperature is 210°C, the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2 mm test piece is injection-molded from it, and the test results are shown in Table 2.

[0159] A polyurethane foam material and its preparation method. The preparation method is as follows: The TPU beads provided in this comparative example are extruded into a 15-mm-thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, heated to 115°C, maintained at a pressure of 20 MPa, and foamed at a constant temperature and pressure for 1.75 h. Then, the carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment to obtain a TPU foam plate. The performance evaluation data is shown in Table 1.

[0160] Comparative Example 3B

[0161] A polyurethane foam material and its preparation method. The preparation method is as follows: Using the TPU beads provided in Comparative Example 3A, a polyurethane foam material is prepared by the same method as in Example 2. The performance evaluation data is shown in Table 1.

[0162] Comparative Example 4A

[0163] A thermoplastic polyurethane elastomer and its preparation method. The preparation method is as follows: By mass, 1 part of PCDL-1500, 0.609 parts of HDI, 0.277 parts of 1,4-butanediol, 0.0007 parts of triethylamine, and 0.005 parts of antioxidant 1010 are transported to the casting system through a gear pump and mixed evenly to obtain a mixture. The mixture is cast on a twin-screw extruder for continuous reaction synthesis to obtain a thermoplastic polyurethane elastomer. The temperatures of the 1st - 10th zones of the twin-screw extruder are respectively: 120°C, 150°C, 155°C, 160°C, 160°C, 190°C, 190°C, 190°C, 220°C, 220°C. The head temperature is 240°C, and the screw speed is 190 rpm. The obtained thermoplastic polyurethane elastomer is cooled and pelletized, and stored below 30°C to obtain TPU beads. A 2-mm test piece is injection-molded from it, and the test results are shown in Table 1.

[0164] A polyurethane foam material and its preparation method. The preparation method is as follows: The TPU beads provided in this comparative example are extruded into a 10-mm-thick plate through a screw extruder. The plate is placed in a foaming kettle, filled with 5 MPa of carbon dioxide and 15 MPa of nitrogen, and then heated to 145°C and foamed at a pressure of 20 MPa for 3 h. The carbon dioxide and nitrogen in the pressure vessel are discharged into the atmospheric environment to obtain a foamed TPU plate. The performance evaluation data is shown in Table 1.

[0165] Comparative Example 4B

[0166] A polyurethane foam material and its preparation method are as follows: Using the TPU beads provided by Comparative Example 4A, a polyurethane foam material is prepared by the same method as in Example 5, and the performance evaluation data is shown in Table 1.

[0167] Table 1

[0168]

[0169] Combined with the data in Table 1, it can be seen that the TPU elastomer provided by the present invention has a complex viscosity of 300 - 100000 Pa·s and a G' / G'' of 0.01 - 100 at 160 °C and 0.01 Hz, enabling its excellent foamability. The polyurethane foam material obtained by foaming it has a high foaming ratio, low density, uniform cell structure, uniform and controllable skin thickness, uniform and stable cell size, low shrinkage rate, and high resilience performance and excellent mechanical properties; among them, the density of the polyurethane foam materials in Examples 1 - 7 is 0.06 - 0.12 g / cm 3 , the falling ball resilience rate is 78 - 82%, the shrinkage rate is 0.8 - 1.5%, and the skin thickness is 20 - 50 μm, which is a foaming material with excellent comprehensive performance.

[0170] By comparing Examples 1 - 7 with Examples 8 - 10, it can be seen that through the process and parameter design of two-stage foaming temperature, pressure relief, and curing during the foaming process of the present invention, the performance of the foam material can be further optimized to obtain a polyurethane foam material with low density, low shrinkage, uniform and controllable skin thickness, and high resilience. In Examples 8 - 9, the one-stage foaming process was used, resulting in imperfect foaming and a slightly thicker skin thickness; in Example 10, no curing was carried out, resulting in imperfect foaming and a large shrinkage.

[0171] The complex viscosity and G' / G'' of the TPU elastomers in Comparative Examples 1A - 2B are not within the range defined by the present invention, resulting in poor foamability. Whether using the conventional foaming process (Comparative Examples 1A, 2A) or the two-stage foaming and curing process preferred by the present invention (Comparative Examples 1B, 2B), the resilience of the obtained foam materials is small. The foaming skin thickness obtained in 1A - 1B is too small, which is not conducive to surface treatment; the skin of 2A - 2B is too thick, which is not beneficial to the foaming ratio.

[0172] Only one of the complex viscosity and G' / G'' of the TPU elastomers in Comparative Examples 3A - 4B is within the range defined by the present invention, and their foamability is still poor. The obtained foam materials have small resilience, large shrinkage, and the skin thickness is not in the optimal range.

[0173] The applicant declares that the present invention illustrates the thermoplastic polyurethane elastomer, polyurethane foam material and their preparation methods and applications through the above embodiments. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the present invention's products, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A polyurethane foam material, characterized in that: The polyurethane foam material is obtained by foaming a thermoplastic polyurethane elastomer, and the complex viscosity of the thermoplastic polyurethane elastomer at 160° C. and 0.01 Hz is 300-100000 Pa·s; The storage modulus of the thermoplastic polyurethane elastomer at 160° C. and 1 Hz is recorded as G', and the loss modulus is recorded as G'', 0.01≤G' / G''≤2; The polyurethane foam material is prepared by the following method, which comprises: using a physical foaming agent to foam the thermoplastic polyurethane elastomer under pressure; after the foaming is completed, the pressure is released and the elastomer is aged to obtain the polyurethane foam material; The foaming includes a first stage of foaming and a second stage of foaming performed sequentially, the temperature of the first stage of foaming is recorded as T1, the temperature of the second stage of foaming is recorded as T2, 5°C≤T2-T1≤20°C; the temperature of the first stage of foaming is 100-160°C, the time is 0.1-24 h; the time of the second stage of foaming is 0.05-5 h; The foaming pressure is 10-65 MPa; The aging temperature is recorded as T3, 0≤T3-T1≤20°C, and the aging time is 0.1-24 h.

2. The polyurethane foam material according to claim 1, characterized in that The thermoplastic polyurethane elastomer has a complex viscosity of 300-50000 Pa·s at 160° C. and 0.01 Hz; And / or, the storage modulus of the thermoplastic polyurethane elastomer at 160° C. and 1 Hz is denoted as G', and the loss modulus is denoted as G'', and 0.01≤G' / G''≤1.

3. The polyurethane foam material according to claim 1 or 2, characterized in that: The thermoplastic polyurethane elastomer is obtained by reacting isocyanate, polyol and chain extender; The isocyanate includes any one of hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, and hydrogenated xylylene diisocyanate, or a combination of at least two thereof; The polyol includes any one of polycarboxylate polyol, polyether polyol, polycarbonate polyol, and polycaprolactone polyol, or a combination of at least two thereof; The chain extender includes any one of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, cyclohexanedimethanol, dihydroxyethyl benzene ether, propylene diamine, butylene diamine, p-phenylenediamine, biphenylenediamine, and 3,3'-dimethyl-4,4-biphenylenediamine, or a combination of at least two thereof; Taking the total mass of the isocyanate, the polyol and the chain extender as 100%, the mass of the isocyanate is 12%-35%, and the mass of the chain extender is 0.7%-25%.

4. The polyurethane foam material according to claim 1 or 2, characterized in that: The Shore hardness of the thermoplastic polyurethane elastomer is 60A-70D.

5. A method for preparing a polyurethane foam material according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: Using a physical foaming agent to foam the thermoplastic polyurethane elastomer under pressure; after the foaming is completed, the pressure is released and the elastomer is aged to obtain the polyurethane foam material; The foaming includes a first stage of foaming and a second stage of foaming performed sequentially, the temperature of the first stage of foaming is recorded as T1, the temperature of the second stage of foaming is recorded as T2, 5°C≤T2-T1≤20°C; the temperature of the first stage of foaming is 100-160°C, the time is 0.1-24 h; the time of the second stage of foaming is 0.05-5 h; The foaming pressure is 10-65 MPa; The aging temperature is recorded as T3, 0≤T3-T1≤20°C, and the aging time is 0.1-24 h.

6. The preparation method according to claim 5, characterized in that: The physical foaming agent includes any one of nitrogen, carbon dioxide, methane, propane, butane, and pentane, or a combination of at least two thereof.

7. The preparation method according to claim 5, characterized in that: The temperature of the second stage foaming is 105-180°C.

8. The preparation method according to claim 5, characterized in that: The aging temperature is 100-180°C.

9. Use of the polyurethane foam material according to any one of claims 1 to 4 in footwear materials, seat materials, tires, decorative materials, cushioning materials, thermal insulation materials, sound insulation materials, toys or sports equipment.

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