Antibacterial TPU (thermoplastic polyurethane) material for drinking water pipe and preparation method of antibacterial TPU material

Abstract

The invention relates to the technical field of polyurethane, and discloses an antibacterial TPU material for a drinking water pipe and a preparation method thereof.The antibacterial TPU material for the drinking water pipe is obtained by putting polyurethane resin and modified graphene into an open mill, mixing and then discharging. The compatibility of the modified graphene and a polyurethane matrix is good, and the tensile strength and the mechanical property of the TPU material are remarkably improved. The modified graphene contains a plurality of hydrophobic alkyl long chains, so that the hydrophobicity and the water resistance of the TPU material can be improved. The imino group contained in the modified graphene is protonized under the action of hydrochloric acid to form an N + positive ion structure containing an alkyl long chain, and the N + positive ion structure can interact with a cell membrane with negative electricity of bacteria, so that the permeability and integrity of the cell membrane are changed, and the effect of killing the bacteria is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethanes, and specifically to an antibacterial TPU material for drinking water pipes and a preparation method thereof. Background Art

[0002] Polyurethane has the advantages of being non-toxic, environmentally friendly, having excellent elasticity, good heat resistance, etc., and is widely used in pipeline materials, sports goods, coatings, inks and other fields. Combining polyurethane with nano-fillers can further improve its mechanical strength, antibacterial, water resistance and other properties. Common nano-fillers include graphene, nano-silica, nano-titanium dioxide, etc.

[0003] Graphene has strong high-temperature resistance, high mechanical strength, and certain bactericidal ability, and has wide applications in polymer materials. Solving the agglomeration problem of graphene and improving its compatibility with the polymer resin matrix is a research difficulty. The Chinese patent with the authorization announcement number CN109096740B discloses an antibacterial and antistatic TPU film material and a preparation method thereof. Using thermoplastic polyurethane elastomer, silver-loaded graphene, aminated carbon nanotubes, etc. as raw materials, the prepared TPU film material has good antibacterial and antistatic properties, but this patent does not improve the water resistance and waterproof performance of the polyurethane material, which is not conducive to its practical application in drinking water pipeline materials and other aspects. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides an antibacterial TPU material for drinking water pipes and a preparation method thereof, which solves the problem of poor compatibility between graphene and polyurethane, improves the water resistance and waterproof performance of the polyurethane material, and at the same time improves the antibacterial performance of the polyurethane.

[0005] The preparation method of the antibacterial TPU material for drinking water pipes provided by the present invention includes the following steps: Step (1): Add N,N-dimethylformamide and graphene oxide to a reaction vessel, ultrasonically disperse, add a modifier, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine. After the reaction, filter, add the product to a hydrochloric acid solution, stir for 2-4 h, filter, wash successively with water and ethanol, and dry to obtain modified graphene; The reaction formula is: .

[0006] The structural formula of the said modifier is ; n is any one of 10-18; Step (2): Place polyurethane resin and modified graphene with a mass ratio of 100:(0.5-4) in an open mill, mix and discharge to obtain an antibacterial TPU material for drinking water pipes.

[0007] Further, in the step (1), the mass ratio of graphene oxide, modifier, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 100:(50 - 200):(22 - 70):(5 - 16).

[0008] Further, in the step (1), the reaction is carried out with stirring at 50 - 65 °C for 6 - 12 h.

[0009] Further, in the step (1), the mass fraction of the hydrochloric acid solution is 2 - 8%.

[0010] Further, in the step (2), the mixing is carried out at 150 - 160 °C for 30 - 40 min.

[0011] Further, the preparation method of the modifier is as follows: Add toluene, ethylene glycol diglycidyl ether, and alkylamine to a reaction vessel, heat to 100 - 110 °C, react for 6 - 10 h, distill off toluene under reduced pressure, wash with petroleum ether, and recrystallize the product in chloroform to obtain the modifier; The reaction formula is: .

[0012] Further, the molar ratio of ethylene glycol diglycidyl ether to alkylamine is 1:(6 - 10).

[0013] Further, the structural formula of the alkylamine is NH2 - C n H 2n+1 , where n is any one of 10 - 18.

[0014] The present invention also provides an antibacterial TPU material for drinking water pipes obtained by the above preparation method.

[0015] Reaction mechanism: In the present invention, ethylene glycol diglycidyl ether and alkylamine are reacted to obtain a modifier. Using dicyclohexylcarbodiimide and 4-dimethylaminopyridine as catalysts, the hydroxyl group of the modifier reacts with the carboxyl group on the surface of graphene oxide to carry out an esterification reaction to obtain modified graphene, and then it is mixed with polyurethane resin at high temperature to obtain the antibacterial TPU material.

[0016] Beneficial effects: 1. After the surface modification of the graphene oxide in the present invention, it is beneficial to improve the dispersibility. And after introducing organic functional groups, the compatibility with the polyurethane matrix becomes better, enabling graphene to have a better strengthening effect and significantly improving the tensile strength and mechanical properties of the TPU material; 2. The modified graphene in the present invention contains multiple hydrophobic alkyl long chains. Adding it to polyurethane is beneficial to improving the hydrophobicity of the material, thereby reducing the water absorption rate and improving the water resistance of the material; 3. The modified graphene in the present invention contains imino groups. Under the action of hydrochloric acid, the imino groups are protonated to form N containing alkyl long chains+ The positive ion structure can interact with the negatively charged cell membrane of bacteria, changing the permeability and integrity of the cell membrane, thereby achieving the effect of killing bacteria, showing a high antibacterial rate, and having good practical applications in antibacterial and water-resistant drinking pipe materials and the like. Specific implementation methods

[0017] The following polyurethane resin, model A92P4637, is sourced from Dongguan Chengjin Plastic Chemical Co., Ltd. Graphene oxide, with a product specification of 0.5 - 3μm, is sourced from Zhongke Leiming (Beijing) Technology Co., Ltd.

[0018] Example 1: Preparation method of antibacterial TPU material for drinking pipes, including the following steps: (1) Add 1L of toluene, 50 mmol of ethylene glycol diglycidyl ether, and 300 mmol of tetradecylamine to a reaction vessel, heat to 110°C, react for 6h, remove toluene by vacuum distillation, wash with petroleum ether, and recrystallize the product in chloroform to obtain a modifier. The structural formula is: .

[0019] (2) Add 1.5L of N,N-dimethylformamide and 2g of graphene oxide to a reaction vessel, ultrasonically disperse, add 1g of modifier, 0.44g of dicyclohexylcarbodiimide, and 0.1g of 4-dimethylaminopyridine, stir and react at 60°C for 6h, filter, add the product to 2L of a hydrochloric acid solution with a mass fraction of 5%, stir for 2h, filter, wash successively with water and ethanol, and dry to obtain modified graphene.

[0020] (3) Place 10kg of polyurethane resin and 50g of modified graphene in an open mill, knead at 160°C for 30min, discharge to obtain an antibacterial TPU material for drinking pipes.

[0021] Example 2: Preparation method of antibacterial TPU material for drinking pipes, including the following steps: (1) Add 1.5L of toluene, 50 mmol of ethylene glycol diglycidyl ether, and 400 mmol of octadecylamine to a reaction vessel, heat to 100°C, react for 10h, remove toluene by vacuum distillation, wash with petroleum ether, and recrystallize the product in chloroform to obtain a modifier. The structural formula is .

[0022] (2) Add 2L of N,N-dimethylformamide and 2g of graphene oxide to a reaction vessel, ultrasonically disperse, add 2.5g of modifier, 0.96g of dicyclohexylcarbodiimide, and 0.22g of 4-dimethylaminopyridine, stir and react at 50°C for 12h, filter, add the product to 2L of a hydrochloric acid solution with a mass fraction of 2%, stir for 4h, filter, wash successively with water and ethanol, and dry to obtain modified graphene.

[0023] (3) Place 10 kg of polyurethane resin and 200 g of modified graphene in an open mill, knead at 150 °C for 40 min, and discharge to obtain an antibacterial TPU material for drinking water pipes.

[0024] Example 3: A preparation method of an antibacterial TPU material for drinking water pipes, comprising the following steps: (1) Add 1.5 L of toluene, 50 mmol of ethylene glycol diglycidyl ether, and 380 mmol of 1-decylamine to a reaction vessel, heat to 110 °C, react for 7 h, distill off toluene under reduced pressure, wash with petroleum ether, and recrystallize the product in chloroform to obtain a modifier. The structural formula is .

[0025] (2) Add 2 L of N,N-dimethylformamide and 2 g of graphene oxide to a reaction vessel, ultrasonically disperse, add 4 g of modifier, 1.4 g of dicyclohexylcarbodiimide, and 0.32 g of 4-dimethylaminopyridine, stir and react at 65 °C for 6 h, filter, add the product to 1.6 L of an 8% hydrochloric acid solution by mass, stir for 2 h, filter, wash successively with water and ethanol, and dry to obtain modified graphene.

[0026] (3) Place 10 kg of polyurethane resin and 400 g of modified graphene in an open mill, knead at 160 °C for 30 min, and discharge to obtain an antibacterial TPU material for drinking water pipes.

[0027] Comparative Example 1: Place 10 kg of polyurethane resin in an open mill, knead at 160 °C for 30 min, and discharge to obtain a TPU material.

[0028] Comparative Example 2: Place 10 kg of polyurethane resin and 50 g of graphene oxide in an open mill, knead at 160 °C for 30 min, and discharge to obtain a TPU material.

[0029] Comparative Example 3: (1) Add 1.5 L of N,N-dimethylformamide and 2 g of graphene oxide to a reaction vessel, ultrasonically disperse, add 1 g of 1-tetradecanol, 0.44 g of dicyclohexylcarbodiimide, and 0.1 g of 4-dimethylaminopyridine, stir and react at 60 °C for 6 h, filter, add the product to 2 L of a 5% hydrochloric acid solution by mass, stir for 2 h, filter, wash successively with water and ethanol, and dry to obtain modified graphene; (2) Place 10 kg of polyurethane resin and 50 g of modified graphene in an open mill, knead at 160 °C for 30 min, and discharge to obtain a TPU material.

[0030] Comparative Example 4: (1) Add 1 L of toluene, 50 mmol of ethylene glycol diglycidyl ether, and 300 mmol of n-propylamine to a reaction vessel, heat to 110 °C, react for 6 h, remove toluene by vacuum distillation, wash with petroleum ether, and dry to obtain a modifier; (2) Add 1.5 L of N,N-dimethylformamide and 2 g of graphene oxide to a reaction vessel, disperse ultrasonically, add 1 g of the modifier, 0.44 g of dicyclohexylcarbodiimide, and 0.1 g of 4-dimethylaminopyridine, stir and react at 60 °C for 6 h, filter, add the product to 2 L of a 5% hydrochloric acid solution by mass, stir for 2 h, filter, wash successively with water and ethanol, and dry to obtain modified graphene; (3) Place 10 kg of polyurethane resin and 50 g of modified graphene in an open mill, knead at 160 °C for 30 min, discharge to obtain a TPU material.

[0031] Mold the TPU material on a flat vulcanizer at 160 °C under a pressure of 10 MPa to make specimens. The tensile properties are tested according to the standard of GB / T 1040.1-2018.

[0032] Dry the TPU specimens, weigh them, soak them in water at 80 °C for 48 h, wipe the surface moisture after taking them out, weigh them, and calculate the water absorption rate W. W = (m - m0) / m0 × 100%. m is the mass of the specimen after water absorption, and m0 is the mass before water absorption.

[0033] The antibacterial property is tested according to the standard of QB / T 2591-2003. The antibacterial rate R = (B - C) / B × 100%. B is the average number of recovered bacteria of the blank control sample (the TPU material of Comparative Example 1). C is the average number of recovered bacteria of the antibacterial sample. The performance test results of the TPU materials obtained by the above method are shown in Table 1 below.

[0034] Table 1: Performance test results of TPU materials of each example and comparative example

[0035] As can be seen from Table 1, the tensile strength of the TPU material of Comparative Example 1 is only 36.7 MPa, and the water absorption rate reaches 7.65%, the water resistance is poor, and at the same time the antibacterial property is poor.

[0036] Graphene oxide was added in Comparative Example 2. Its compatibility with polyurethane is poor, the dispersion is not good, it is easy to agglomerate, and the strengthening effect on polyurethane is low, resulting in a small increase in the tensile strength of the TPU material, and it does not reduce the water absorption rate of the TPU material, nor does it significantly improve the antibacterial property.

[0037] In Examples 1-3, modified graphene was added. After surface modification, the dispersibility of graphene became better, and its compatibility with the polyurethane matrix was excellent, significantly improving the tensile strength of the TPU material. At the same time, the modified graphene contains multiple hydrophobic alkyl long chains, and adding it to polyurethane is beneficial to improving the hydrophobicity of the material, thereby reducing the water absorption rate and improving the water resistance of the material. Moreover, the modified graphene contains imino groups. Under the action of hydrochloric acid, the imino groups are protonated to form an N + cationic structure, which can interact with the negatively charged cell membrane of bacteria, change the permeability and integrity of the cell membrane, and thus achieve the effect of killing bacteria, showing a very high antibacterial rate.

[0038] In Comparative Example 3, 1-tetradecanol was used to carry out an esterification reaction with the carboxyl group of graphene oxide. It only contains one hydrophobic alkyl long chain and does not effectively reduce the hydrophobicity and water absorption rate of the TPU material, resulting in poor water resistance of the material. Moreover, the graphene modified with 1-tetradecanol does not contain imino groups and cannot be protonated with hydrochloric acid, and no N + cationic structure is formed, and the antibacterial performance of the material is poor.

[0039] The modifier in Comparative Example 4 does not contain multiple hydrophobic alkyl long chains, resulting in the modified graphene not significantly reducing the water absorption rate of the TPU material and having a low antibacterial rate.

[0040] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an antibacterial TPU material for a drinking water pipe, characterized in that: The following steps are involved: Step (1): Add N,N-dimethylformamide and graphene oxide to a reaction container, perform ultrasonic dispersion, add a modifier, dicyclohexylcarbodiimide and 4-dimethylaminopyridine, filter after reaction, add the product to a hydrochloric acid solution, stir for 2-4 hours, filter, wash with water and ethanol in sequence, and dry to obtain modified graphene; The structural formula of the modifier is ; n is any one of 10-18; Step (2): placing a polyurethane resin and modified graphene in a mass ratio of 100:(0.5-4) in an open mixer, mixing and discharging the mixture, and obtaining an antibacterial TPU material for drinking water pipes.

2. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 1, characterized in that: In the step (1), the mass ratio of graphene oxide, modifier, dicyclohexylcarbodiimide and 4-dimethylaminopyridine is 100:(50-200):(22-70):(5-16).

3. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 1, characterized in that: In the step (1), the reaction is stirred at 50-65° C. for 6-12 hours.

4. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 1, characterized in that: The mass fraction of the hydrochloric acid solution in step (1) is 2-8%.

5. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 1, characterized in that: In the step (2), the mixing is carried out at 150-160° C. for 30-40 minutes.

6. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 2, characterized in that: The preparation method of the modifier is as follows: toluene, ethylene glycol diglycidyl ether and alkylamine are added into a reaction container, heated to 100-110° C., reacted for 6-10 hours, toluene is removed by reduced pressure distillation, petroleum ether is washed, and the product is recrystallized in chloroform to obtain the modifier.

7. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 6, characterized in that: The molar ratio of ethylene glycol diglycidyl ether to alkylamine is 1:(6-10).

8. The method for preparing the antibacterial TPU material for drinking water pipes according to claim 7, characterized in that: The structural formula of the alkylamine is NH2-C n H 2n+1 , n is any one between 10-18.

9. An antibacterial TPU material for drinking water pipes obtained by the preparation method according to any one of claims 1 to 8.

Images