Thermoplastic polyurethane elastomer material, thermoplastic polyurethane foam material and preparation and application thereof

Abstract

This invention discloses a thermoplastic polyurethane elastomer material, a thermoplastic polyurethane foam material, its preparation method, and its applications. The invention introduces an intermediate product containing a prepolymer end-capped with a single NCO group. The NCO groups in the prepolymer and the amide bonds of the thermoplastic polyurethane elastomer undergo an addition reaction in a twin-screw extruder. This allows the molecular chain segments of the prepolymer to be grafted onto the molecular chain segments of the thermoplastic polyurethane elastomer, forming a branched molecular chain structure in the thermoplastic polyurethane. This improves the melt strength of the low molecular weight thermoplastic polyurethane elastomer, thereby enhancing its foaming properties. The resulting thermoplastic polyurethane foam material exhibits lower density, more uniform cell structure, better resilience, and excellent mechanical properties, and is essentially free of chemical crosslinking, allowing for recycling.

Description

Technical Field

[0001] This invention relates to the field of lightweight polymer materials, specifically to a thermoplastic polyurethane elastomer material, a thermoplastic polyurethane foam material, and their preparation methods and applications. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU) is a semi-crystalline polymer material prepared by combining diisocyanate, long-chain diol and short-chain diol in a certain proportion on a belt system or in a reactive extruder.

[0003] TPU possesses excellent mechanical properties, excellent heat and chemical resistance, and excellent abrasion resistance. Furthermore, due to the diversity of its raw material formulation, products with a very wide range of hardness can be obtained by adjusting the proportions of each ingredient.

[0004] Foamed TPU materials are obtained by filling a large number of air bubbles inside TPU using TPU resin as a matrix through extrusion foaming or autoclave foaming. These foamed TPU materials typically have a series of advantages such as low density, heat and sound insulation, high specific strength, high elasticity, and cushioning, and are therefore widely used in packaging, industry, agriculture, transportation, military industry, aerospace industry, and daily necessities.

[0005] Thermoplastic polyurethane (TPU) foam materials and their preparation methods have been disclosed in numerous patent documents, such as WO2007082838A1, WO2010136398A1, and CN102276785A. During TPU foaming, the foaming agent expands within the TPU matrix, forming individual small bubbles. This necessitates that the TPU possess high melt strength to prevent pore breakage and cross-contamination, while also enabling the production of lighter materials.

[0006] TPU has a linear molecular chain structure with virtually no chemical cross-linking, which allows it to be recycled and reused. However, recycling requires melting, heating, and regranulation, which shortens the TPU molecular chain, reduces melt strength, and lowers mechanical properties. This makes it impossible to re-foam the recycled TPU, limiting its use in other fields as well.

[0007] Patent specification CN112029133A discloses a polyurethane foam material and its preparation method. This polyurethane foam material uses thermoplastic polyurethane elastomer as the skeleton material, reacting it with isocyanate-terminated polyurethane, water, a catalyst, and selectively added functional additives to create foam, which is then prepared by extrusion. Specifically, the isocyanate-terminated polyurethane is prepared by reacting polyisocyanate in a stoichiometric excess with a polymeric polyol; that is, the polyurethane used in this patent technology has isocyanate groups at both ends. Summary of the Invention

[0008] In a first aspect, the present invention provides a method for preparing a thermoplastic polyurethane elastomer material, comprising the steps of:

[0009] (1) With or without a catalyst, diisocyanate and diol are mixed at a feed ratio of 1.3-3.0 and reacted completely. Then, monohydroxy alcohol and / or monoamino amine compound are added to continue the reaction to obtain an intermediate product containing a prepolymer capped with a monoNCO group. The amount of the monohydroxy alcohol and / or monoamino amine compound added is 40%-60% of the molar number of NCO groups remaining after the complete reaction, preferably 50% of the molar number of NCO groups remaining after the complete reaction. This is beneficial to increasing the proportion of the prepolymer capped with the monoNCO group in the intermediate product, reducing the chemical crosslinking of the thermoplastic polyurethane elastomer material caused by the addition of the intermediate product, and promoting the formation of more branched structures in the thermoplastic polyurethane elastomer material after the addition of the intermediate product.

[0010] (2) The thermoplastic polyurethane elastomer and the intermediate product are fed into a twin-screw extruder for melt reaction extrusion to obtain the thermoplastic polyurethane elastomer material;

[0011] The thermoplastic polyurethane elastomer material contains a branched structure, which is formed by the prepolymer with the single NCO group end capping and the thermoplastic polyurethane elastomer being connected by the reaction of the NCO end group and the amide bond.

[0012] Secondly, the present invention provides a method for preparing a thermoplastic polyurethane foam material, comprising the steps of:

[0013] (1) With or without a catalyst, diisocyanate and diol are mixed at a feed ratio of 1.3-3.0 and reacted completely. Then, monohydroxy alcohol and / or monoamino amine compound are added to continue the reaction to obtain an intermediate product containing a prepolymer capped with a monoNCO group. The amount of the monohydroxy alcohol and / or monoamino amine compound added is 40%-60% of the molar number of NCO groups remaining after the complete reaction, preferably 50% of the molar number of NCO groups remaining after the complete reaction. This is beneficial to increasing the proportion of the prepolymer capped with the monoNCO group in the intermediate product, reducing the chemical crosslinking of the thermoplastic polyurethane elastomer material caused by the addition of the intermediate product, and promoting the formation of more branched structures in the thermoplastic polyurethane elastomer material after the addition of the intermediate product.

[0014] (2) The thermoplastic polyurethane elastomer and the intermediate product are fed into a twin-screw extruder for melt reaction extrusion and pelletizing to obtain thermoplastic polyurethane elastomer beads.

[0015] The thermoplastic polyurethane elastomer beads contain a branched structure, which is formed by the prepolymer with the single NCO group end capping and the thermoplastic polyurethane elastomer being connected by the NCO end group and the amide bond.

[0016] (3) The thermoplastic polyurethane elastomer beads, physical foaming agent and water are mixed in a high-pressure container to form a suspension, and then the suspension is heated and pressurized, and finally the pressure is released to obtain the thermoplastic polyurethane foam material.

[0017] According to the preparation method of the first or second aspect of the present invention, in step (1), the R value refers to the ratio of the molar equivalent of NCO groups in the diisocyanate to the molar equivalent of OH groups in the diol. An excessively large R value will result in a low molecular weight of the prepolymer with a single NCO group end-capping in the prepared intermediate product, affecting the melt strength of the thermoplastic polyurethane elastomer material, and consequently affecting the performance of the thermoplastic polyurethane foam material. Conversely, an excessively small R value will result in a low NCO group content in the prepolymer with a single NCO group end-capping in the prepared intermediate product, which is not conducive to improving the melt strength of the thermoplastic polyurethane elastomer material, and consequently affects the performance of the thermoplastic polyurethane foam material.

[0018] According to the preparation method of the first or second aspect of the present invention, in step (1), the catalyst can adjust the reaction rate and can be bis(2-morpholinodiethyl) ether (DMDEE) or the like.

[0019] According to the preparation method of the first or second aspect of the present invention, in step (1), the diisocyanate may be at least one of toluene diisocyanate, diphenylmethane diisocyanate, 3-isocyanate-methylene-3,5,5-trimethylcyclohexyl isocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, terephthalic diisocyanate, 1,4-cyclohexane diisocyanate, and cyclohexane-dimethylene diisocyanate, preferably at least one of diphenylmethane-4,4' diisocyanate and hexamethylene diisocyanate.

[0020] According to the preparation method of the first or second aspect of the present invention, in step (1), the diol may be a macromolecular diol with a number average molecular weight of 600-4000 g / mol, and may be selected from one or more of polyester polyol, polyether polyol, polycarbonate polyol, and polycaprolactone polyol.

[0021] According to the preparation method of the first or second aspect of the present invention, in step (1), the temperature of the complete reaction can be 50-120°C, and the time of the complete reaction can be adjusted according to the actual situation, for example, it can be 10-180 min.

[0022] According to the preparation method of the first or second aspect of the present invention, in step (1), the monohydroxy alcohol may be at least one of diethylene glycol butyl ether, diethylene glycol monomethyl ether, 1,4-butanediol monomethyl ether, and diethylene glycol monopentyl ether.

[0023] According to the preparation method of the first or second aspect of the present invention, in step (1), the monoaminoamine compound may be at least one of octadecylamine, tetradecylamine, heptylamine, hexadecylamine, nonylamine, octylamine, and cycloheptylamine.

[0024] According to the preparation method of the first or second aspect of the present invention, in step (1), the temperature of the continued reaction can be 70-140°C, and the time of the continued reaction can be adjusted according to the actual situation, with the goal of ensuring that the reaction proceeds fully. For example, it can be 10-180 min. The double NCO-terminated material after complete reaction in step (1) has a certain viscosity. Appropriately increasing the temperature during the continued reaction process is beneficial for the complete reaction of NCO with monohydroxy alcohols and / or monoamino amine compounds.

[0025] According to the preparation method of the first or second aspect of the present invention, in step (1), the number-average molecular weight of the intermediate product can be 1000-30000 g / mol.

[0026] According to the preparation method of the first or second aspect of the present invention, in step (2), the number-average molecular weight of the thermoplastic polyurethane elastomer is preferably 30,000-120,000 g / mol. When the number-average molecular weight of the thermoplastic polyurethane elastomer is higher than 120,000 g / mol, there is basically no need to add the intermediate product for branching, and it can be directly used for foaming; if the number-average molecular weight of the thermoplastic polyurethane elastomer is too low, then the molecular weight of the intermediate product must be high and the amount added must be large, which will result in a poor reaction mixing effect in the twin-screw extruder.

[0027] According to the preparation method of the first or second aspect of the present invention, in step (2), based on the total mass of the thermoplastic polyurethane elastomer and the intermediate product being 100%, the mass percentage of the intermediate product can be 1%-30%, preferably 5%-30%, to ensure sufficient branched structure. If too little intermediate product is added, the branched structure in the thermoplastic polyurethane elastomer material will be less, the melt strength will not be well improved, and the foam of the plastic polyurethane foam material will easily have cross-cells and broken cells, and the corresponding resilience and mechanical properties will also be poor.

[0028] According to the preparation method of the first or second aspect of the present invention, in step (2), the Shore hardness of the thermoplastic polyurethane elastomer can be 40A-80D.

[0029] According to the preparation method of the first or second aspect of the present invention, in step (2), the intermediate product can be heated by a hot melt adhesive machine and then metered and fed into the twin-screw extruder.

[0030] According to the preparation method of the first or second aspect of the present invention, in step (2), the thermoplastic polyurethane elastomer can be metered and fed into the twin-screw extruder using a loss-in-weight method.

[0031] According to the preparation method of the first or second aspect of the present invention, in step (2), the melt reaction extrusion temperature of the twin-screw extruder can be 100-220℃, the main machine speed can be 100-300rpm, and the screw length-to-diameter ratio can be 30-56:1.

[0032] According to the preparation method of the second aspect of the present invention, in step (3), the physical foaming agent may be one or a mixture of several of nitrogen, carbon dioxide, butane, pentane and pentafluoropropane.

[0033] According to the preparation method of the second aspect of the present invention, in step (3), the heating temperature can be 80-180°C, and the pressurization pressure can be 30-150 bar.

[0034] Thirdly, the present invention provides a thermoplastic polyurethane elastomer material prepared according to the preparation method described in the first aspect.

[0035] Fourthly, the present invention provides the use of the thermoplastic polyurethane elastomer material according to the third aspect in the preparation of thermoplastic polyurethane foam materials.

[0036] Fifthly, the present invention provides a thermoplastic polyurethane foam material prepared according to the preparation method described in the second aspect.

[0037] In some embodiments, the density of the thermoplastic polyurethane foam material is 0.06-0.4 g / cm³. 3 Furthermore, the density of the thermoplastic polyurethane foam material is 0.06-0.3 g / cm³. 3 .

[0038] In a sixth aspect, the present invention provides the application of the thermoplastic polyurethane elastomer material according to the third aspect or the thermoplastic polyurethane foam material according to the fifth aspect in the field of footwear materials, such as in soles, insoles, uppers, etc.

[0039] The thermoplastic polyurethane foam material of the present invention has the characteristics of low density, uniform cell size, good resilience and excellent mechanical properties. Furthermore, the present invention enables low molecular weight thermoplastic polyurethane elastomers to be used in foaming, thus broadening the application scenarios of low molecular weight thermoplastic polyurethane elastomers.

[0040] Compared with the prior art, the beneficial effects of this invention are as follows:

[0041] This invention introduces an intermediate product containing a prepolymer capped with a single NCO group. The NCO group in the prepolymer capped with a single NCO group undergoes an addition reaction with the amide bond of the thermoplastic polyurethane elastomer in a twin-screw extruder. This allows the molecular chain segments of the prepolymer capped with a single NCO group to be grafted onto the molecular chain segments of the thermoplastic polyurethane elastomer, thereby forming a branched molecular chain structure in the thermoplastic polyurethane. This improves the melt strength of the low molecular weight thermoplastic polyurethane elastomer, and thus improves its foaming properties. The resulting thermoplastic polyurethane foam material has lower density, more uniform cell structure, better resilience, and excellent mechanical properties. Furthermore, it is essentially free of chemical crosslinking and can be recycled. Attached Figure Description

[0042] Figure 1 This is a 50x transmission electron microscope image of the cross-section of the thermoplastic polyurethane foam material prepared in Example 1 of the present invention.

[0043] Figure 2This is a 50x transmission electron microscope image of the cross-section of the thermoplastic polyurethane foam material prepared in Comparative Example 1 of this invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0045] Example 1

[0046] (1) First, 47.55 kg of diphenylmethane-4,4'-diisocyanate and 100 kg of polytetrahydrofuran diol with a number average molecular weight of 1000 g / mol were added to a reactor with an R value of 1.9. The temperature was raised to 100°C and the reaction was carried out for 60 min. After the reaction was complete, 14.60 kg of diethylene glycol butyl ether was added to the reactor, and the temperature was raised to 120°C and the reaction was carried out for 60 min to prepare an intermediate product of a prepolymer with a single NCO group end cap. The number average molecular weight of the prepolymer was tested to be 4000 g / mol. In this example, the molar amount of diethylene glycol butyl ether added was 50% of the molar amount of NCO groups remaining after the complete reaction.

[0047] (2) 90 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 85A and a number-average molecular weight of 70,000 g / mol and 10 parts by weight of the intermediate product of the prepolymer containing single NCO groups in (1) were fed into a twin-screw extruder for melt reaction extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads with a branched structure. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 160-190℃, and a main extruder speed of 200 rpm.

[0048] (3) Add 10 kg of branched thermoplastic polyurethane elastomer beads from (2), 8 kg of carbon dioxide, and 20 kg of water to a high-pressure container and stir to form a suspension. Then heat the suspension to 118°C, maintain the pressure at 85 bar, and finally quickly depressurize. Remove the material to obtain thermoplastic polyurethane foam. Test its cell size under a microscope. See [reference needed]. Figure 1 .

[0049] (4) Take the thermoplastic polyurethane foam material obtained in (3) and fill it into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Use water vapor at a pressure of 2 bar to compress the particles by 10% along the thickness direction of the mold to form a molded foam product. Then, dry the molded foam product in an oven at 70°C for 2 hours and then place it at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0050] Example 2

[0051] (1) First, 36.45 kg of hexamethylene diisocyanate and 100 kg of polytetrahydrofuran diol with a number average molecular weight of 600 g / mol were added to a reactor with an R value of 1.3. The temperature was raised to 120°C and the reaction was carried out for 20 min. After the reaction was complete, 8.11 kg of diethylene glycol butyl ether was added to the reactor, and the temperature was raised to 140°C and the reaction was carried out for 20 min to prepare an intermediate product of a prepolymer with a single NCO group end cap. The number average molecular weight of the prepolymer was tested to be 10000 g / mol. In this example, the molar amount of diethylene glycol butyl ether added was 50% of the molar amount of NCO groups remaining after the complete reaction.

[0052] (2) 70 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 55D and a number-average molecular weight of 30,000 g / mol and 30 parts by weight of the intermediate product of the prepolymer containing single NCO groups in (1) were fed into a twin-screw extruder for melt reaction extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads with a branched structure. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 180-220℃, and a main extruder speed of 300 rpm.

[0053] (3) 10 kg of thermoplastic polyurethane elastomer beads with branched structure from (2), 8 kg of carbon dioxide and 20 kg of water are put into a high-pressure container and stirred to form a suspension. The suspension is then heated to 125°C and the pressure is maintained at 90 bar. Finally, the pressure is released quickly and the material is taken out to obtain thermoplastic polyurethane foam material. Its cell size is tested by microscope.

[0054] (4) The thermoplastic polyurethane foam material obtained in (3) is filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 2.3 bar is used to compress the particles by 10% along the thickness direction of the mold to form a molded foam product. The molded foam product is then dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0055] Example 3

[0056] (1) First, 11.21 kg of hexamethylene diisocyanate and 100 kg of polybutanediol adipate diol with a number average molecular weight of 3000 g / mol were added to a reactor with an R value of 2. The temperature was raised to 70°C and the reaction was carried out for 180 min. After the reaction was complete, 10.79 kg of octadecylamine was added to the reactor, and the temperature was raised to 90°C and the reaction was carried out for 180 min to prepare an intermediate product of a prepolymer with a single NCO group end cap. The number average molecular weight was tested to be 3300 g / mol. In this example, the molar amount of octadecylamine added was 60% of the molar amount of NCO groups remaining after the complete reaction.

[0057] (2) 80 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 75D and a number-average molecular weight of 50,000 g / mol and 20 parts by weight of the intermediate product of the prepolymer containing single NCO groups in (1) were fed into a twin-screw extruder for melt reaction extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads with a branched structure. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 170-200℃, and a main extruder speed of 220 rpm.

[0058] (3) 10 kg of thermoplastic polyurethane elastomer beads with branched structure from (2), 8 kg of carbon dioxide, 4 kg of nitrogen, and 20 kg of water were put into a high-pressure container and stirred to form a suspension. The suspension was then heated to 128°C and the pressure was maintained at 150 bar. Finally, the pressure was released quickly and the material was taken out to obtain thermoplastic polyurethane foam material. Its cell size was tested by microscope.

[0059] (4) The thermoplastic polyurethane foam material obtained in (3) is filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 2.6 bar is used to compress the particles by 10% along the thickness direction of the mold to form a molded foam product. The molded foam product is then dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0060] Example 4

[0061] (1) First, 75.07 kg of diphenylmethane-4,4'-diisocyanate and 100 kg of polycaprolactone diol with a number average molecular weight of 1000 g / mol were added to a reactor with an R value of 3. The temperature was raised to 50°C and the reaction was carried out for 120 min. After the reaction was complete, 18.43 kg of heptamine was added to the reactor, and the temperature was raised to 70°C and the reaction was carried out for 120 min to prepare an intermediate product of a prepolymer with a single NCO group end cap. The number average molecular weight of the prepolymer was tested to be 1100 g / mol. In this example, the molar amount of heptamine added was 40% of the molar amount of NCO groups remaining after the complete reaction.

[0062] (2) 95 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 60A and a number-average molecular weight of 120,000 g / mol and 5 parts by weight of the intermediate product of the prepolymer containing single NCO groups in (1) were fed into a twin-screw extruder for melt reaction extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads with a branched structure. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 100-130℃, and a main extruder speed of 100 rpm.

[0063] (3) 10 kg of branched thermoplastic polyurethane elastomer beads, 8 kg of butane and 20 kg of water from (2) were put into a high-pressure container and stirred to form a suspension. The suspension was then heated to 108°C and the pressure was maintained at 30 bar. Finally, the pressure was released quickly and the material was taken out to obtain thermoplastic polyurethane foam material. Its cell size was tested by microscope.

[0064] (4) The thermoplastic polyurethane foam material obtained in (3) is filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 1.3 bar is used to compress the particles by 10% along the thickness direction of the mold to form a molded foam product. The molded foam product is then dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0065] Comparative Example 1

[0066] Comparative Example 1 does not include the intermediate product of the prepolymer containing a single NCO group end-capping. The specific steps are as follows:

[0067] (1) 100 parts by weight of thermoplastic polyurethane elastomer with a Shore hardness of 85A and a number-average molecular weight of 70,000 g / mol were fed into a twin-screw extruder for melt reaction extrusion, and then pelletized underwater through a die to obtain thermoplastic polyurethane elastomer beads. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 160-190℃, and a main extruder speed of 200 rpm.

[0068] (2) Add 10 kg of thermoplastic polyurethane elastomer beads, 8 kg of carbon dioxide, and 20 kg of water from (1) to a high-pressure container and stir to form a suspension. Then heat the suspension to 110°C (the foaming temperature was optimized and adjusted according to the molecular weight of the thermoplastic polyurethane elastomer beads), maintain the pressure at 85 bar, and finally quickly depressurize to remove the material to obtain thermoplastic polyurethane foam material. Test its cell size under a microscope. See [reference needed]. Figure 2 .

[0069] (3) The thermoplastic polyurethane foam material obtained in (2) was filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 1.6 bar (the pressure was optimized and adjusted according to the molecular weight of the thermoplastic polyurethane foam material) was used to compress the particles by 10% along the thickness direction of the mold to bond and form the molded foam product. The molded foam product was then dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0070] Comparative Example 2

[0071] The intermediate product of Comparative Example 2 is not NCO-terminated. The specific steps are as follows:

[0072] (1) First, 47.55 kg of diphenylmethane-4,4'-diisocyanate and 100 kg of polytetrahydrofuran diol with a number average molecular weight of 1000 g / mol were added to a reaction vessel with an R value of 1.9. The temperature was raised to 100°C and the reaction was carried out for 60 min. After the reaction was complete, 29.18 kg of diethylene glycol butyl ether was added to the reaction vessel, and the temperature was raised to 120°C and the reaction was carried out for 60 min to prepare an intermediate product without NCO end capping. The number average molecular weight of the intermediate product was tested to be 4200 g / mol. In this example, the molar amount of diethylene glycol butyl ether added was 100% of the molar amount of NCO groups remaining after the complete reaction.

[0073] (2) 90 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 85A and a molecular weight of 70,000 g / mol and 10 parts by weight of the NCO-free intermediate product from (1) were fed into a twin-screw extruder for melt extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads without branched structures. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 160-190℃, and a main extruder speed of 200 rpm.

[0074] (3) 10 kg of thermoplastic polyurethane elastomer beads without branched structure from (2), 8 kg of carbon dioxide and 20 kg of water were put into a high-pressure container and stirred to form a suspension. The suspension was then heated to 113°C (the foaming temperature was optimized and adjusted according to the actual situation of the thermoplastic polyurethane elastomer beads), and the pressure was kept at 85 bar. Finally, the pressure was released quickly, and the material was taken out to obtain thermoplastic polyurethane foam material. Its cell size was tested by microscope.

[0075] (4) The thermoplastic polyurethane foam material obtained in (3) is filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 1.8 bar (the pressure was optimized and adjusted according to the actual situation of the thermoplastic polyurethane foam material) is used to compress the particles by 10% along the thickness direction of the mold to bond and form the molded foam product. The molded foam product is then dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0076] Comparative Example 3

[0077] Comparative Example 3 does not include monohydroxy alcohols and / or monoamino amine compounds; that is, the intermediate products are all isocyanate double-terminated. The specific steps are as follows:

[0078] (1) First, 47.55 kg of diphenylmethane-4,4' diisocyanate and 100 kg of polytetrahydrofuran diol with a number average molecular weight of 1000 g / mol were added to the reactor with an R value of 1.9. The temperature was raised to 100℃ and the reaction was carried out for 60 min. After the reaction was complete, a double NCO-terminated intermediate product was obtained, and its number average molecular weight was tested to be 3900 g / mol.

[0079] (2) 90 parts by weight of a thermoplastic polyurethane elastomer with a Shore hardness of 85A and a molecular weight of 70,000 g / mol and 10 parts by weight of the NCO-free intermediate product from (1) were fed into a twin-screw extruder for melt extrusion. The pellets were then cut underwater through a die to obtain thermoplastic polyurethane elastomer beads without branched structures. The twin-screw extruder had a screw length-to-diameter ratio of 45:1, an extruder temperature of 160-190℃, and a main extruder speed of 200 rpm.

[0080] (3) 10 kg of thermoplastic polyurethane elastomer beads without branched structure from (2), 8 kg of carbon dioxide and 20 kg of water were put into a high-pressure container and stirred to form a suspension. The suspension was then heated to 128°C (the foaming temperature was optimized and adjusted according to the actual situation of the thermoplastic polyurethane elastomer beads), and the pressure was kept at 85 bar. Finally, the pressure was released quickly, and the material was taken out to obtain thermoplastic polyurethane foam material. Its cell size was tested by microscope.

[0081] (4) The thermoplastic polyurethane foam material obtained in (3) is filled into a mold with a length of 300 mm × width of 150 mm × thickness of 10 mm. Water vapor at a pressure of 2.6 bar (the pressure was optimized and adjusted according to the actual situation of the thermoplastic polyurethane foam material) is used to compress the particles by 10% along the thickness direction of the mold to bond and form the final molded foam product. Then the molded foam product is dried in an oven at 70°C for 2 hours and then placed at room temperature for 2 hours to evaluate its performance, as shown in Table 1.

[0082] Table 1

[0083]

[0084] As can be seen from the data in Table 1 and the accompanying figures, the thermoplastic polyurethane foam material and its products of the present invention have lower density, more uniform cell structure, better resilience, and excellent mechanical properties. Comparative Example 1, due to the low molecular weight and low melt viscosity of the thermoplastic polyurethane elastomer, resulted in cross-contamination and broken cells in the prepared thermoplastic polyurethane foam material, and consequently, poorer resilience and mechanical properties. Comparative Example 2, due to the absence of a thermoplastic polyurethane elastomer that did not form a branched structure, also exhibited the problems of Comparative Example 1. Comparative Example 3 used isocyanate-terminated intermediates, chemically cross-linking the thermoplastic polyurethane elastomer and improving its melt strength. While it could also produce thermoplastic polyurethane foam materials with lower density, more uniform cell structure, and better resilience during foaming, the presence of the chemical cross-linked structure led to poor adhesion between beads during steam molding, resulting in a significant decrease in the mechanical properties of the thermoplastic polyurethane foam material products. Furthermore, the large number of chemical cross-linked structures made the prepared thermoplastic polyurethane foam material unrecyclable.

[0085] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A process for the preparation of a thermoplastic polyurethane elastomer material, characterized in that, The method comprises the steps of: (1) mixing and completely reacting diisocyanate and dihydric alcohol with a R value of 1.3-3.0 in the presence or absence of a catalyst, and then adding monohydric alcohol and / or monoamino amine compound to continue the reaction to obtain an intermediate product containing a pre-polymer terminated by a single NCO group; the amount of the monohydric alcohol and / or monoamino amine compound added is 40%-60% of the number of moles of the remaining NCO groups after the complete reaction; (2) melting and reacting the thermoplastic polyurethane elastomer and the intermediate product in a twin-screw extruder to obtain the thermoplastic polyurethane elastomer material; The thermoplastic polyurethane elastomer material contains branched structures formed by the reaction of the single NCO group terminated pre-polymer and the thermoplastic polyurethane elastomer through NCO end groups and amide bonds.

2. The production method according to claim 1, characterized by, In step (1): The catalyst is bis(2-morpholinediethyl) ether; The diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, 3-isocyanate methylene-3,5,5-trimethylcyclohexyl isocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, 1,4-cyclohexane diisocyanate, and cyclohexane dimethylene diisocyanate; The dihydric alcohol is a macromolecular dihydric alcohol with a number average molecular weight of 600-4000 g / mol, selected from one or more of polyester polyol, polyether polyol, polycarbonate polyol, and polycaprolactone polyol; The complete reaction temperature is 50-120°C; The monohydric alcohol is at least one of diethylene glycol butyl ether, diethylene glycol monomethyl ether, 1,4-butanediol monomethyl ether, and diethylene glycol monopentyl ether; The monoamino amine compound is at least one of octadecylamine, tetradecylamine, heptylamine, hexadecylamine, nonylamine, octylamine, and cycloheptylamine; The continue reaction temperature is 70-140°C; The number average molecular weight of the intermediate product is 1000-30000 g / mol; The amount of the monohydric alcohol and / or monoamino amine compound added is 50% of the number of moles of the remaining NCO groups after the complete reaction.

3. The production method according to claim 2, characterized by, In step (1), the diisocyanate is at least one of diphenylmethane-4,4' diisocyanate and hexamethylene diisocyanate.

4. The preparation method according to claim 1, characterized in that, In step (2): The number average molecular weight of the thermoplastic polyurethane elastomer is 30000-120000 g / mol; The mass percentage of the intermediate product in the total mass of the thermoplastic polyurethane elastomer and the intermediate product is 1%-30%; The Shore hardness of the thermoplastic polyurethane elastomer is 40A-80D; The intermediate product is metered into the twin-screw extruder after being heated by a hot melt glue machine; The thermoplastic polyurethane elastomer can be metered into the twin-screw extruder by a loss-on-ignition balance; The melting and reaction extrusion temperature of the twin-screw extruder is 100-220°C, the main machine rotation speed is 100-300 rpm, and the screw length-diameter ratio is 30-56:

1.

5. The production method according to claim 4, characterized by, In step (2), the mass percentage of the intermediate product is 5-30% based on the total mass of the thermoplastic polyurethane elastomer and the intermediate product being 100%.

6. A method for producing a thermoplastic polyurethane foam material, characterized by, The method comprises the following steps: (1) mixing and completely reacting diisocyanate and dihydric alcohol in a feed ratio with an R value of 1.3-3.0 in the presence or absence of a catalyst, and then adding a monohydric alcohol and / or a monoamino amine compound to continue the reaction to obtain an intermediate product containing a pre-polymer terminated by a single NCO group; the amount of the monohydric alcohol and / or the monoamino amine compound added is 40-60% of the number of moles of the remaining NCO groups after the complete reaction; (2) feeding the thermoplastic polyurethane elastomer and the intermediate product into a twin-screw extruder for melt reaction extrusion and pelletization to obtain thermoplastic polyurethane elastomer beads; The thermoplastic polyurethane elastomer beads contain branched structures formed by the NCO terminal group of the pre-polymer terminated by a single NCO group and the thermoplastic polyurethane elastomer connected by NCO terminal group and amide bond reaction; (3) mixing the thermoplastic polyurethane elastomer beads, a physical foaming agent and water in a high-pressure container to form a suspension, then heating and pressurizing the suspension, and finally depressurizing to obtain the thermoplastic polyurethane foaming material.

7. The production method according to claim 6, wherein In step (1), the catalyst is bis(2-morpholinoethyl) ether; The diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, 1,4-cyclohexane diisocyanate, and cyclohexane dimethylene diisocyanate; The dihydric alcohol is a macromolecular dihydric alcohol with a number average molecular weight of 600-4000 g / mol, selected from one or more of polyester polyol, polyether polyol, polycarbonate polyol, and polycaprolactone polyol; The temperature of the complete reaction is 50-120°C; The monohydric alcohol is at least one of diethylene glycol butyl ether, diethylene glycol monomethyl ether, 1,4-butanediol monomethyl ether, and diethylene glycol monopentyl ether; The monoamino amine compound is at least one of octadecylamine, tetradecylamine, heptylamine, hexadecylamine, nonylamine, octylamine, and cycloheptylamine; The temperature of the continued reaction is 70-140°C; The number average molecular weight of the intermediate product is 1000-30000 g / mol; The amount of the monohydric alcohol and / or the monoamino amine compound added is 50% of the number of moles of the remaining NCO groups after the complete reaction. In step (1), the diisocyanate is at least one of diphenylmethane-4,4’ diisocyanate and hexamethylene diisocyanate.

8. The production method according to claim 7, characterized by, In step (2), the number average molecular weight of the thermoplastic polyurethane elastomer is 30000-120000 g / mol; 9. The preparation method according to claim 6, characterized in that, The mass percentage of the intermediate product is 1-30% based on the total mass of the thermoplastic polyurethane elastomer and the intermediate product being 100%. ​ ​ The Shore hardness of the thermoplastic polyurethane elastomer is 40A-80D; The intermediate product is metered into the twin-screw extruder after being heated by a hot melt glue machine; The thermoplastic polyurethane elastomer can be metered into the twin-screw extruder by a loss on drying balance; The melt reaction extrusion temperature of the twin-screw extruder is 100-220℃, the main machine rotation speed is 100-300rpm, and the screw length-diameter ratio is 30-56:

1.

10. The method of claim 9, wherein, In step (2), the mass percentage of the intermediate product is 5%-30% based on the total mass of the thermoplastic polyurethane elastomer and the intermediate product being 100%.

11. The preparation method according to claim 6, characterized in that, In step (3): The physical foaming agent is one or a mixture of several of nitrogen, carbon dioxide, butane, pentane, and pentafluoropropane; The heating temperature is 80-180℃, and the pressurizing pressure is 30-150bar.

12. A thermoplastic polyurethane elastomer material prepared by the preparation method of claim 1.

13. Use of the thermoplastic polyurethane elastomer material of claim 12 in the preparation of a thermoplastic polyurethane foamed material.

14. A thermoplastic polyurethane foamed material prepared by the preparation method of claim 6.

15. The thermoplastic polyurethane foam according to claim 14, wherein, The thermoplastic polyurethane foam has a density of 0.06 to 0.4 g / cm 3 .

16. The thermoplastic polyurethane foam according to claim 15, wherein, The thermoplastic polyurethane foam has a density of 0.06 to 0.3 g / cm3 3 .

17. Use of the thermoplastic polyurethane elastomer material of claim 12 or the thermoplastic polyurethane foamed material of any one of claims 14-16 in the field of shoe materials.

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