High-strength and impact-resistant TPU composite material and preparation method

Abstract

The invention relates to the technical field of polyurethanes and discloses a high-strength and impact-resistant TPU composite material and a preparation method. The high-strength and impact-resistant TPU composite material comprises 60-85 parts by weight of a polyurethane resin, 15-40 parts by weight of polyoxymethylene, and 1-4 parts by weight of a hydroxy polyurethane. The hydroxy polyurethane has a molecular main chain similar to that of the polyurethane resin, and a side chain containing a hydroxyl group, which forms a hydrogen bond with an ether bond of the polyoxymethylene, so that the hydroxy polyurethane plays a role in compatibilizing the polyurethane resin and the polyoxymethylene, significantly improving the compatibility between the two, forming an alloy system with better mechanical properties, and making the TPU composite material have higher tensile strength and maintain good impact strength. The hydroxy polyurethane contains a fused ring structure with high temperature resistance and is not easily thermally decomposed, which is conducive to improving the heat resistance of the TPU composite material and increasing the initial thermal decomposition temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane, in particular to a high-strength and impact-resistant TPU composite material and a preparation method thereof. Background Art

[0002] Polyurethane boasts high toughness, excellent impact resistance, and superior weather resistance, making it widely used in materials such as pipes, fibers, foams, and films. Conventional polyurethane suffers from low mechanical strength. Compounding polyurethane with engineering plastics such as polyoxymethylene, nylon, and polyimide creates alloy plastics with enhanced mechanical properties.

[0003] Polyoxymethylene (POM) has high strength, high modulus, and good wear resistance, making it widely used. However, its compatibility with polyurethane is poor, and its addition to polyurethane can affect its toughness, impact strength, and other properties. Patent application number CN118307949A discloses a thermoplastic polyurethane composite material, its preparation method, and its application. Using a polymer containing epoxy groups, such as acrylonitrile-styrene-glycidyl methacrylate, as a compatibilizer, a thermoplastic polyurethane elastomer and polyoxymethylene are blended. The resulting polyurethane composite exhibits excellent mechanical properties and electrical conductivity. However, the patent application fails to improve the impact strength and heat resistance of the polyoxymethylene-polyurethane material. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a high-strength and impact-resistant TPU composite material and a preparation method, which solves the problem of poor compatibility between polyurethane and polyoxymethylene, as well as the problem of low mechanical strength of polyurethane.

[0005] The high-strength and impact-resistant TPU composite material of the present invention comprises 60-85 parts by weight of polyurethane resin, 15-40 parts by weight of polyoxymethylene, and 1-4 parts by weight of hydroxy polyurethane.

[0006] The preparation method of high-strength and impact-resistant TPU composite material phenol is as follows:

[0007] (1) Add diisocyanate, 5,7-dihydroxy-4'-methoxyflavone and dibutyltin dilaurate to a solvent, stir and react, distill under reduced pressure, wash the product with ethanol, and dry it to obtain methoxy polyurethane.

[0008] (2) Add methoxy polyurethane to dichloromethane, and in a nitrogen atmosphere, dropwise add a dichloromethane solution containing boron tribromide. After the reaction, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane. The reaction formula is: .

[0009] (3) The polyurethane resin, polyoxymethylene and hydroxy polyurethane are mixed and added into a twin-screw extruder, extruded and granulated to obtain a high-strength and impact-resistant TPU composite material.

[0010] Furthermore, the solvent in (1) includes toluene, tetrahydrofuran or dichloromethane.

[0011] Furthermore, the reaction temperature in (1) is 60-80°C, and the reaction time is 2-3h.

[0012] Furthermore, the molar ratio of diisocyanate, 5,7-dihydroxy-4'-methoxyflavone, and dibutyltin dilaurate in (1) is 1:(1-1.06):(0.05-0.07).

[0013] Furthermore, the diisocyanate in (1) is diphenylmethane-4,4'-diisocyanate, toluene-2,4-diisocyanate or isophorone diisocyanate.

[0014] Furthermore, the mass ratio of methoxy polyurethane and boron tribromide in (2) is 100:(56-72).

[0015] Furthermore, the reaction in (2) is first carried out at 0-5°C for 2-3 h, and then at 15-25°C for 8-12 h.

[0016] Furthermore, the temperature of zones 1-6 of the twin-screw extruder in (3) is 150-190°C, and the screw speed is 200-300 r / min.

[0017] Beneficial effects: The present invention polymerizes diisocyanate and 5,7-dihydroxy-4'-methoxyflavone, and then demethylates them with boron tribromide to obtain a hydroxy polyurethane containing a condensed ring structure and a large number of hydroxyl groups, which is then blended with a polyurethane resin and polyformaldehyde to obtain a TPU composite material. The hydroxy polyurethane has a similar molecular backbone to the polyurethane resin, and the side chains contain hydroxyl groups, which can form hydrogen bonds with the ether bonds of polyformaldehyde, allowing the hydroxy polyurethane to act as a compatibilizer for the polyurethane resin and polyformaldehyde, significantly improving the compatibility between the two and forming an alloy system with better mechanical properties. This allows the TPU composite material to have higher tensile strength and maintain good impact strength. In addition, the hydroxy polyurethane contains a condensed ring structure with high temperature resistance and is not easily thermally decomposed, which is beneficial for improving the heat resistance of the TPU composite material and increasing the initial thermal decomposition temperature. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] The polyurethane resin model A92P4637 was obtained from Dongguan Chengjin Plastics Co., Ltd. The polyoxymethylene model POMAW-02 was purchased from Suzhou Shengxinlong Plastics Co., Ltd.

[0020] Example 1: A method for preparing a high-strength and impact-resistant TPU composite material, comprising the following steps:

[0021] (1) Add 0.1 mol of toluene-2,4-diisocyanate, 0.1 mol of 5,7-dihydroxy-4'-methoxyflavone (CAS No. 480-44-4), and 6 mmol of dibutyltin dilaurate to 250 mL of toluene, heat to 70°C, stir and react for 3 h, distill under reduced pressure, wash the product with ethanol, and dry it to obtain methoxy polyurethane;

[0022] (2) Add 80 g of methoxy polyurethane to 1.8 L of dichloromethane, add dropwise 300 mL of dichloromethane solution containing 51.4 g of boron tribromide at 0°C in a nitrogen atmosphere, stir and react for 3 h, then react at 20°C for 12 h, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane;

[0023] (3) 8.5 kg of polyurethane resin, 1.5 kg of polyoxymethylene, and 100 g of hydroxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 300 r / min. The mixture was extruded and granulated to obtain a high-strength and impact-resistant TPU composite material.

[0024] Example 2: A method for preparing a high-strength and impact-resistant TPU composite material, comprising the following steps:

[0025] (1) Add 0.1 mol of isophorone diisocyanate, 0.106 mol of 5,7-dihydroxy-4'-methoxyflavone, and 5 mmol of dibutyltin dilaurate to 300 mL of dichloromethane, heat to 80°C, stir and react for 2 h, distill under reduced pressure, wash the product with ethanol, and dry it to obtain methoxy polyurethane;

[0026] (2) Add 80 g of methoxy polyurethane to 2 L of dichloromethane, add dropwise 320 mL of dichloromethane solution containing 57.6 g of boron tribromide at 0 ° C in a nitrogen atmosphere, stir and react for 3 h, then react at 25 ° C for 8 h, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane;

[0027] (3) 8 kg of polyurethane resin, 2 kg of polyoxymethylene, and 170 g of hydroxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 200 r / min. Extrusion and granulation were performed to obtain a high-strength and impact-resistant TPU composite material.

[0028] Example 3: A method for preparing a high-strength and impact-resistant TPU composite material, comprising the following steps:

[0029] (1) Add 0.1 mol of diphenylmethane-4,4'-diisocyanate, 0.104 mol of 5,7-dihydroxy-4'-methoxyflavone, and 5.3 mmol of dibutyltin dilaurate to 300 mL of toluene, heat to 70°C, stir and react for 3 h, distill under reduced pressure, wash the product with ethanol, and dry it to obtain methoxy polyurethane;

[0030] (2) Add 80 g of methoxy polyurethane to 2 L of dichloromethane, add 250 mL of dichloromethane solution containing 44.8 g of boron tribromide dropwise at 5 ° C in a nitrogen atmosphere, stir and react for 3 h, then react at 20 ° C for 12 h, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane;

[0031] (3) 7 kg of polyurethane resin, 3 kg of polyoxymethylene, and 280 g of hydroxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 200 r / min. Extrusion and granulation were performed to obtain a high-strength and impact-resistant TPU composite material.

[0032] Example 4: A method for preparing a high-strength and impact-resistant TPU composite material, comprising the following steps:

[0033] (1) Add 0.1 mol toluene-2,4-diisocyanate, 0.106 mol 5,7-dihydroxy-4'-methoxyflavone, and 7 mmol dibutyltin dilaurate to 300 mL tetrahydrofuran, heat to 60°C, stir and react for 3 h, distill under reduced pressure, wash the product with ethanol, and dry to obtain methoxy polyurethane;

[0034] (2) Add 80 g of methoxy polyurethane to 1.8 L of dichloromethane, add 320 mL of dichloromethane solution containing 49.6 g of boron tribromide dropwise at 5 ° C in a nitrogen atmosphere, stir and react for 3 h, then react at 15 ° C for 12 h, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane;

[0035] (3) 6 kg of polyurethane resin, 4 kg of polyoxymethylene, and 400 g of hydroxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 200 r / min. Extrusion and granulation were performed to obtain a high-strength and impact-resistant TPU composite material.

[0036] Comparative Example 1: 8.5 kg of polyurethane resin and 1.5 kg of polyoxymethylene were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C. The screw speed was 300 r / min, and the mixture was extruded and granulated to obtain a TPU composite material.

[0037] Comparative Example 2: (1) Methoxy polyurethane was prepared according to the method of Example 1;

[0038] (2) 8.5 kg of polyurethane resin, 1.5 kg of polyoxymethylene, and 100 g of methoxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 300 r / min. The mixture was extruded and granulated to obtain a TPU composite material.

[0039] Comparative Example 3: A method for preparing a TPU composite material, comprising the following steps:

[0040] (1) Add 0.1 mol of toluene-2,4-diisocyanate, 0.1 mol of 5-methoxyresorcinol (CAS No. 2174-64-3), and 6 mmol of dibutyltin dilaurate to 250 mL of toluene, heat to 70°C, stir and react for 3 h, distill under reduced pressure, wash the product with ethanol, and dry it to obtain methoxy polyurethane;

[0041] (2) Add 80 g of methoxy polyurethane to 1.8 L of dichloromethane, add dropwise 300 mL of dichloromethane solution containing 51.4 g of boron tribromide at 0°C in a nitrogen atmosphere, stir and react for 3 h, then react at 20°C for 12 h, pour the solution into ice water, stir, filter, wash with water and ethanol, and dry to obtain hydroxy polyurethane;

[0042] (3) 8.5 kg of polyurethane resin, 1.5 kg of polyoxymethylene, and 100 g of hydroxy polyurethane were mixed and added to a twin-screw extruder. The temperatures in zones 1-6 were 150°C, 175°C, 185°C, 185°C, 190°C, and 190°C, and the screw speed was 300 r / min. The mixture was extruded and granulated to obtain a TPU composite material.

[0043] TPU materials were compression molded in a flat-plate vulcanizer at 180°C and 10 MPa pressure to produce specimens. Tensile properties were tested according to GB / T 1040.1-2018. Impact strength was tested according to GB / T 1043.1-2008.

[0044] 10 mg of TPU material was weighed and placed in a thermogravimetric analyzer to test the thermal properties in a nitrogen atmosphere at a temperature range of 30-700°C.

[0045] The performance test results of the TPU composite materials of various embodiments and comparative examples obtained by the above test methods are shown in Table 1 below.

[0046] Table 1: Performance test results of TPU composite materials of various embodiments and comparative examples

[0047] Comparative Example 1: Polyurethane resin is blended with polyoxymethylene. The tensile strength and impact strength of the obtained TPU composite material are low. This is mainly because the compatibility between the polyurethane resin and the polyoxymethylene is poor, resulting in low mechanical strength of the composite material. Hydroxyl polyurethane is added to the TPU composite materials of Examples 1 to 4. The molecular main chain of the polyurethane resin is similar, and the side chain contains hydroxyl groups, which can form hydrogen bonds with the ether bonds of the polyoxymethylene. The hydroxyl polyurethane plays the role of compatibilizing the polyurethane resin and the polyoxymethylene, significantly improving the compatibility between the two, forming an alloy system with better mechanical properties, so that the composite material has higher tensile strength and maintains good impact strength. In addition, the hydroxyl polyurethane contains a condensed ring structure with high temperature resistance ( ), is not easy to thermally decompose, which is beneficial to improving the heat resistance of TPU composite materials and increasing the initial (mass loss 5%) thermal decomposition temperature.

[0048] The TPU composite material of Comparative Example 2 is added with methoxy polyurethane, which does not contain hydroxyl groups and has weak hydrogen bonding with the ether bonds of polyformaldehyde, making it difficult to play the role of compatibilizing polyurethane resin and polyformaldehyde, resulting in low tensile strength and impact strength of the composite material.

[0049] In Comparative Example 3, 5-methoxyresorcinol was used as a raw material to prepare a hydroxy polyurethane which did not contain a fused ring structure with high temperature resistance, resulting in the initial thermal decomposition temperature of the polyurethane being lower than that in Example 1.

[0050] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. High-strength and impact-resistant TPU composite material, characterized by: The invention comprises 60-85 parts by weight of polyurethane resin, 15-40 parts by weight of polyoxymethylene, and 1-4 parts by weight of hydroxy polyurethane; The preparation method of the hydroxy polyurethane is: (1) adding diisocyanate, 5,7-dihydroxy-4'-methoxyflavone and dibutyltin dilaurate to a solvent, stirring to react, distilling under reduced pressure, washing the product, and drying to obtain methoxy polyurethane; (2) Add methoxy polyurethane to dichloromethane, and dropwise add a dichloromethane solution containing boron tribromide in a nitrogen atmosphere. After the reaction, pour the solution into ice water, stir, filter, wash the product, and dry it to obtain hydroxy polyurethane.

2. The high-strength and impact-resistant TPU composite material according to claim 1, characterized in that: The solvent in (1) includes toluene, tetrahydrofuran or dichloromethane.

3. The high-strength and impact-resistant TPU composite material according to claim 1, characterized in that: The reaction temperature in (1) is 60-80°C and the reaction time is 2-3h.

4. The high-strength and impact-resistant TPU composite material according to claim 1, characterized in that: The molar ratio of diisocyanate, 5,7-dihydroxy-4'-methoxyflavone and dibutyltin dilaurate in (1) is 1: (1-1.06): (0.05-0.07).

5. The high-strength and impact-resistant TPU composite material according to claim 4, characterized in that: The diisocyanate is diphenylmethane-4,4'-diisocyanate, toluene-2,4-diisocyanate or isophorone diisocyanate.

6. The high-strength and impact-resistant TPU composite material according to claim 1, characterized in that: The mass ratio of methoxy polyurethane to boron tribromide in (2) is 100:(56-72).

7. The high-strength and impact-resistant TPU composite material according to claim 1, characterized in that: The reaction in (2) is first carried out at 0-5°C for 2-3 hours, and then at 15-25°C for 8-12 hours.

8. The method for preparing a high-strength and impact-resistant TPU composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing polyurethane resin, polyoxymethylene and hydroxy polyurethane, adding the mixture into a twin-screw extruder, extruding, and granulating to obtain a high-strength and impact-resistant TPU composite material.

9. The method for preparing a high-strength and impact-resistant TPU composite material according to claim 8, wherein: The temperature of zones 1-6 of the twin-screw extruder is 150-190° C., and the screw speed is 200-300 r / min.