A bio-based antibacterial aqueous polyurethane dispersion, its preparation method and application

Abstract

The present invention belongs to the technical field of polyurethane materials, and specifically relates to a bio-based antibacterial aqueous polyurethane dispersion, and further discloses its preparation method and application. The bio-based antibacterial aqueous polyurethane dispersion of the present invention is based on polyols and diisocyanates as raw materials, and reacts through a system in the presence of a hydrophilic chain extender, a neutralizing agent, an antibacterial capping agent, an alcohol chain extender, an amine chain extender and a catalyst. During the reaction process, the addition of the antibacterial capping agent enables antibacterial groups to be formed on the molecular chain of the polyurethane product, thereby obtaining an essential antibacterial resin, which can achieve very excellent antibacterial effects without adding external antibacterial agents, and the antibacterial performance persistence and stability of the product are better, and its application performance is greatly improved, and it can be widely applied to application fields such as water-based adhesives, coatings and inks.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyurethane materials, and particularly relates to a bio-based antibacterial aqueous polyurethane dispersion, and further discloses a preparation method and application thereof. Background Art

[0002] Due to the advantages of environmental friendliness, environmental protection and excellent performance, aqueous polyurethane resin materials have been widely used in the fields of coatings, adhesives and inks in recent years. The raw materials for traditional synthetic polyurethanes mainly include polyols, isocyanates, chain extenders and emulsifiers, almost all of which are derived from petrochemical resources. Due to their non-renewability and non-conformity with the development direction of green chemistry, etc., there are certain limitations on the synthesis of polyurethane materials. In view of this, recently many reports have used natural products such as castor oil, dextrin, starch, etc. as modified raw materials to synthesize resins, and the use of these green and renewable resources has greatly promoted the sustainability of resin synthesis.

[0003] Diphenolic acid (DPA) is a chemical raw material synthesized from levulinic acid and phenol under acid catalysis, and is also one of the biomass platform compounds with great application prospects proposed by the US Department of Energy in 2004. Since the DPA molecular structure contains two hydroxyl groups and one carboxyl functional group, it is a highly designable molecular structure and is soluble in polar solvents such as hot water and acetone, which provides great convenience for its industrial application. DPA has a similar structure to bisphenol A and is an important polymer monomer. At present, it has been widely used in the synthesis of high molecular materials such as benzoxazine, polycarbonate, polyester, hyperbranched polymers, etc. At present, there is no report on the use of DPA in the synthesis process of aqueous polyurethane. The field expects that using DPA as a raw material to synthesize aqueous resins can not only save the use of petrochemical resources, but also promote the development of green chemistry.

[0004] In addition, since polyurethane emulsions are extremely vulnerable to bacterial contamination during synthesis, storage and transportation, and downstream use, resulting in deterioration, it is usually necessary to add bactericides for antibacterial, but often due to the difficulty in maintaining the persistence of bactericides, product scrapping is inevitable. In addition, end products prepared from polyurethanes also have relatively high requirements for antibacterial performance in some special application fields. Such products mostly achieve antibacterial requirements through externally added antibacterial agents such as silver nanoparticles. However, most externally added antibacterial agents are difficult to achieve uniform dispersion with polyurethane materials, and the blind spots of antibacterial agents are also easily attacked by bacteria, seriously affecting the application of downstream products. In addition, chitosan is a natural antibacterial material, but due to the characteristics of the multi-hydroxyl structure of chitosan, it is easy to cause the viscosity of the prepolymer to be too high and it is difficult or impossible to disperse, and it is also not suitable for antibacterial use in aqueous polyurethane dispersions.

[0005] Therefore, it is of positive significance to develop a polyurethane material with inherent antibacterial properties. Summary of the Invention

[0006] To this end, the technical problem to be solved by the present invention is to provide a bio-based antibacterial aqueous polyurethane dispersion. The polyurethane dispersion is prepared based on biomass raw materials, and the main chain of the corresponding resin molecule has antibacterial groups, which not only overcomes the deficiencies of additive antibacterial agents, but also has the advantages of environmental friendliness and green environmental protection.

[0007] The second technical problem to be solved by the present invention is to provide a preparation method of the above bio-based antibacterial aqueous polyurethane dispersion.

[0008] The object of the present invention is to synthesize an aqueous polyurethane dispersion with bisphenolic acid as a hydrophilic group and citric acid as an antibacterial component from biomass raw materials. The resin prepared by this method uses biomass raw materials, which helps to reduce the utilization rate of petrochemical resources and is of great significance for the sustainable development of the chemical industry. In addition, the main chain of the corresponding resin molecule has antibacterial groups, which overcomes the deficiencies of additive antibacterial agents. The prepared resin can be used in fields such as coatings, adhesives and inks.

[0009] To solve the above technical problems, a bio-based antibacterial aqueous polyurethane dispersion according to the present invention comprises the following raw material components in parts by weight: 70-90 parts by weight of polyol, 8-20 parts by weight of diisocyanate, 0.005-0.05 parts by weight of hydrophilic chain extender, 0.01-0.05 parts by weight of neutralizer, 0.01-0.05 parts by weight of antibacterial capping agent, 0.001-0.05 parts by weight of alcohol chain extender, 0.01-0.05 parts by weight of amine chain extender, and 0.001-0.005 parts by weight of catalyst. Specifically, the antibacterial capping agent in the present invention refers to a monofunctional substance capable of reacting with isocyanate, which can play a capping role and at the same time has antibacterial properties. The raw material substances mainly include citric acid in the present invention. The citric acid, as an antibacterial component, has a functional group of a single hydroxyl group and three carboxyl groups, and can also be used as a hydrophilic capping agent at the same time.

[0010] Specifically, the hydrophilic chain extender includes bisphenolic acid, or a mixture of bisphenolic acid and dimethylolpropionic acid and / or dimethylolbutyric acid. In the present invention, bisphenolic acid can be used alone as a hydrophilic chain extender, or as a replacement substance to partially replace conventional dimethylolpropionic acid and / or dimethylolbutyric acid. The higher the proportion used, the higher the bio-based content of the polyurethane product of the present invention.

[0011] Specifically, the bio-based antibacterial aqueous polyurethane dispersion:

[0012] The polyol includes one or a mixture of several of polyester polyol or polyether polyol; preferably, the polyol is a polyester polyol or a polyether polyol with a functionality of 2 and a number average molecular weight of 500-6000 g / mol, or a mixture of the two.

[0013] The diisocyanate includes one or a mixture of several of tetramethylene diisocyanate, methyl pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclopropylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'- and 2,4'-diphenylmethane diisocyanate, tetramethylxylene diisocyanate, p-phenylenedimethyl diisocyanate or p-isopropylidene diisocyanate;

[0014] The neutralizing agent includes one or a mixture of several of triethylamine, ammonia water, and sodium hydroxide;

[0015] The alcohol chain extender includes one or a mixture of several of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-dihydroxycyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol or 2-ethyl-1,3-hexanediol;

[0016] The amine chain extender includes one or a mixture of several of 1,2-ethylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, isophorone diamine, 4,4-diaminodicyclohexylmethane, and piperazine; when the amine chain extender is used, it is formulated into an aqueous solution and added to the reaction system. Preferably, the concentration of the aqueous solution of the amine chain extender is 14-20 wt%;

[0017] The catalyst includes one or a mixture of several of organozinc, organobismuth, and organotin catalysts.

[0018] The present invention also discloses a method for preparing the bio-based antibacterial aqueous polyurethane dispersion, which includes the following steps:

[0019] (1) Under an inert atmosphere, a selected amount of the polyol, alcohol chain extender, isocyanate, hydrophilic chain extender, and antibacterial capping agent are mixed evenly and subjected to a polymerization reaction until the NCO content reaches the theoretical value to obtain a terminal isocyanate group prepolymer;

[0020] (2) The terminal isocyanate group prepolymer is diluted with the polar aprotic solvent, and a selected amount of the neutralizing agent is added for a neutralization reaction, and then water is added for dispersion to obtain a polyurethane emulsion;

[0021] (3) Add an aqueous solution of a selected amount of the amine chain extender to the polyurethane emulsion for chain extension reaction to obtain the desired aqueous polyurethane dispersion.

[0022] Specifically, the polar aprotic solvent includes at least one of acetone, methyl ethyl ketone, tert-butyl methyl ether or tetrahydrofuran, preferably methyl ethyl ketone or acetone, and more preferably acetone;

[0023] Specifically, the amount of the polar aprotic solvent used is 0.5 - 1.5 times the total amount of the polyol, diisocyanate and hydrophilic chain extender;

[0024] Specifically, in step (1), a step of adding a part of the polar aprotic solvent is further included; the amount of the polar aprotic solvent added in step (1) accounts for > 0 - 25% of the total amount of the polar aprotic solvent used.

[0025] Specifically, the preparation method of the bio-based antibacterial aqueous polyurethane dispersion:

[0026] In step (1), the temperature of the polymerization reaction is 70 - 90 °C; and / or,

[0027] In step (2), the addition temperature of the polar aprotic solvent is 20 - 60 °C; and / or,

[0028] In step (2), the addition temperature of the neutralizing agent is 10 - 38 °C; and / or,

[0029] In step (3), the temperature of the chain extension reaction is 20 - 50 °C, and preferably the reaction is carried out for more than 2 minutes.

[0030] Specifically, in step (2), it is preferred to add water under stirring for dispersion for 1 - 18 minutes, and more preferably to add water under stirring for dispersion for 2 - 8 minutes.

[0031] Specifically, in step (3), a step of partially removing or completely removing the polar aprotic solvent after the reaction is completed is further included.

[0032] The present invention also discloses the application of the bio-based antibacterial aqueous polyurethane dispersion or the bio-based antibacterial aqueous polyurethane dispersion prepared by the method in the fields of coatings, adhesives or inks.

[0033] The bio-based antibacterial aqueous polyurethane dispersion of the present invention is based on polyols and diisocyanates as raw materials, and reacts in the presence of a hydrophilic chain extender, a neutralizer, an antibacterial capping agent, an alcohol chain extender, an amine chain extender and a catalyst. During the reaction, the addition of the antibacterial capping agent causes antibacterial groups to form on the molecular chain of the polyurethane product, thereby obtaining an inherently antibacterial resin, which can achieve very excellent antibacterial effects without adding external antibacterial agents. The antibacterial performance of the product has better persistence and stability, and its application performance is greatly improved, and it can be widely applied to application fields such as aqueous adhesives, coatings and inks.

[0034] For the bio-based antibacterial aqueous polyurethane dispersion of the present invention, citric acid is preferably used as the antibacterial capping agent. Citric acid not only has a certain antibacterial effect, but also has a functional group with a single hydroxyl group and three carboxyl groups, and at the same time has good hydrophilicity. It can be introduced into the aqueous polyurethane system as a hydrophilic capping agent for aqueous polyurethane dispersions, and can be used to prepare inherently antibacterial aqueous polyurethane dispersions. While obtaining an aqueous polyurethane dispersion with inherent antibacterial properties, the application properties such as the dispersibility and stability of the product are effectively ensured.

[0035] The bio-based antibacterial aqueous polyurethane dispersion of the present invention uses bio-based bisphenolic acid and citric acid to replace the petrochemical-based hydrophilic chain extender and capping agent materials selected in traditional aqueous polyurethane dispersions, which can reduce the usage amount of petrochemical resources, conforms to the development concept of green chemistry, and has the advantages of environmental friendliness and green environmental protection. Detailed implementation mode

[0036] To better understand the technical solution of the present invention, the content of the present invention will be further elaborated below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments.

[0037] The raw materials and sources of the following examples and comparative examples of the present invention are as follows:

[0038] Polyether polyol I: Poly(propylene oxide) glycol, CAS: 25322-69-4, Mn = 1000, functionality 2 (C2010D, Wanhua Chemical);

[0039] Polyether polyol II: Poly(propylene oxide) glycol, CAS: 25322-69-4, Mn = 4000, functionality 2 (DL-4000D, Bluestar Dongda);

[0040] Catalyst: Bicat3228, (Leading Chemical);

[0041] DPA: Bisphenolic acid (TCI);

[0042] Citric acid: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0043] BDO: 1,4 - butanediol (BASF);

[0044] DMPA: 2,2 - dimethylolpropionic acid (Perstrop);

[0045] N-(2 - hydroxyethyl)-ethylenediamine: BASF Corporation;

[0046] HDI: hexamethylene diisocyanate (HDI, Wanhua Chemical);

[0047] TDI: toluene diisocyanate (TDI - 80, Wanhua Chemical).

[0048] The measuring methods for the parameters in the following examples of the present invention are as follows:

[0049] Average particle size: Dilute the aqueous polyurethane dispersion with water to a concentration of 0.5 wt%, and measure it using Malvern Nano - ZS90;

[0050] -NCO determination: According to the Chemical Industry Standard of the People's Republic of China "HG / T2409-92 Determination of the content of isocyanate groups in polyurethane prepolymers", determine the content of -NCO during the polyurethane synthesis process;

[0051] Antibacterial experiment: Adopt the colony counting method, take Escherichia coli as the research object, add a bacterial concentration of 1*10 5.6 CFU / mL -1 , and an antibacterial powder concentration of 0.001 g / mL, and co - culture for 3 hours.

[0052] Example 1

[0053] The preparation method of the aqueous polyurethane dispersion described in this example includes the following steps:

[0054] (1) Under nitrogen protection, take 265 g of polyether polyol I, 5 g of DPA, 6 g of BDO, 12 g of citric acid, 0.36 g of Bicat3228, 72 g of TDI - 80, and 54 g of acetone and add them to a 1 L four - necked round - bottom flask equipped with nitrogen inlet and outlet. Stir the mixture at 80 °C until the -NCO no longer decreases, and stop the reaction;

[0055] (2) Cool the system to 50 °C and add 360 g of acetone for dilution, then cool it to 35 °C. Add 7.2 g of triethylamine (component e) for neutralization under stirring, react for 10 min under stirring, and then add 580 g of deionized water for dispersion within 10 min under stirring at a speed of 1200 revolutions to obtain a polyurethane emulsion;

[0056] (3) 30 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) was added to the polyurethane emulsion after dispersion was completed for chain extension reaction; after the reaction ended, acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0057] After testing, the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 175 nm.

[0058] Example 2

[0059] The preparation method of the aqueous polyurethane dispersion in this example includes the following steps:

[0060] (1) Under nitrogen protection, 300 g of polyether polyol I, 150 g of polyether polyol II, 11.3 g of DPA, 5.95 g of BDO, 11 g of citric acid, 0.6 g of Bicat3228, 95.3 g of TDI-80, and 86 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet, and the mixture was stirred at 90 °C until the -NCO no longer decreased, then the reaction was stopped;

[0061] (2) The reaction system was cooled to 50 °C and diluted with 573 g of acetone, then cooled to 30 °C again. 7.20 g of triethylamine was added for neutralization under stirring, and the reaction was carried out for 10 min under stirring. Then, 580 g of deionized water was added for dispersion within 10 min under stirring at a speed of 1200 rpm to obtain a polyurethane emulsion;

[0062] (3) 50 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) was added to the above-mentioned polyurethane emulsion after dispersion was completed for chain extension reaction; then acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0063] After testing, the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 180 nm.

[0064] Example 3

[0065] The preparation method of the aqueous polyurethane dispersion in this example includes the following steps:

[0066] (1) Under nitrogen protection, 120 g of polyether polyol I, 260 g of polyether polyol II, 9 g of DPA, 5 g of DMPA, 8.3 g of BDO, 8 g of citric acid, 0.5 g of Bicat3228, 70.5 g of HDI, and 72 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet, and the mixture was stirred at 70 °C until the -NCO no longer decreased, then the reaction was stopped;

[0067] (2) Cool down the reaction system to 50 °C, add 483 g of acetone for dilution, then cool down to 35 °C again. Add 6.52 g of triethylamine for neutralization under stirring, react for 10 min under stirring, and then add 580 g of deionized water for dispersion within 10 min under stirring at a speed of 1200 rpm to obtain a polyurethane emulsion;

[0068] (3) Add 44 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) to the polyurethane emulsion after the above dispersion is completed for chain extension reaction. After the reaction ends, separate acetone by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0069] After testing, the solid content of the aqueous polyurethane dispersion is 50 wt%, and the average particle size is 190 nm.

[0070] Example 4

[0071] The preparation method of the aqueous polyurethane dispersion in this example includes the following steps:

[0072] (1) Under nitrogen protection, add 120 g of polyether polyol I, 260 g of polyether polyol II, 9 g of DPA, 5 g of DMPA, 8.3 g of BDO, 8 g of citric acid, 0.5 g of Bicat3228, 32.5 g of HDI, 40.5 g of TDI, and 72 g of acetone into a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet. Stir the mixture at 70 °C until the -NCO no longer decreases, and then stop the reaction;

[0073] (2) Cool down the reaction system to 50 °C and add 483 g of acetone for dilution, then cool down to 35 °C again. Add 6.52 g of triethylamine for neutralization under stirring, react for 10 min under stirring, and then add 580 g of deionized water for dispersion within 10 min under stirring at a speed of 1200 rpm to obtain a polyurethane emulsion;

[0074] (3) Add 40 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) to the polyurethane emulsion after the above dispersion is completed for chain extension reaction. After the reaction ends, separate acetone by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0075] After testing, the solid content in the aqueous polyurethane dispersion is 50 wt%, and the average particle size is 185 nm.

[0076] Example 5

[0077] The preparation method of the aqueous polyurethane dispersion in this example includes the following steps:

[0078] (1) Under nitrogen protection, 252 g of polyether polyol I, 10 g of DMPA, 2 g of BDO, 18 g of citric acid, 0.36 g of Bicat3228, 78 g of TDI-80, and 54 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet. The mixture was stirred at 80 °C until the -NCO no longer decreased, and the reaction was stopped;

[0079] (2) The system was cooled to 50 °C and diluted with 360 g of acetone. Subsequently, it was cooled to 35 °C, and 7.2 g of triethylamine (component e) was added under stirring for neutralization. The reaction was carried out under stirring for 10 min, and then 580 g of deionized water was added dropwise within 10 min under stirring at 1200 rpm to obtain a polyurethane emulsion;

[0080] (3) 30 g of an aqueous solution of N-(2-hydroxyethyl)-ethylenediamine (concentration 15 wt%) was added to the polyurethane emulsion after dispersion for chain extension reaction; after the reaction was completed, acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0081] It was detected that the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 195 nm.

[0082] Example 6

[0083] The preparation method of the aqueous polyurethane dispersion described in this example includes the following steps:

[0084] (1) Under nitrogen protection, 450 g of polyether polyol II, 1 g of DPA, 3 g of DMPA, 1 g of BDO, 5 g of citric acid, 0.5 g of Bicat3228, 10 g of HDI, 30 g of TDI, and 72 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet. The mixture was stirred at 70 °C until the -NCO no longer decreased, and the reaction was stopped;

[0085] (2) The reaction system was cooled to 50 °C and diluted with 500 g of acetone. It was cooled to 35 °C again, and 6.52 g of triethylamine was added under stirring for neutralization. The reaction was carried out under stirring for 10 min, and then 580 g of deionized water was added dropwise within 10 min under stirring at 1200 rpm to obtain a polyurethane emulsion;

[0086] (3) 40 g of an aqueous solution of N-(2-hydroxyethyl)-ethylenediamine (concentration 15 wt%) was added to the polyurethane emulsion after the above dispersion for chain extension reaction. After the reaction was completed, acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0087] It was detected that the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 215 nm.

[0088] Comparative Example 1

[0089] The preparation method of the aqueous polyurethane dispersion described in this comparative example includes the following steps:

[0090] (1) Under nitrogen protection, 130 g of polyether polyol I, 260 g of polyether polyol II, 9 g of DPA, 5 g of DMPA, 8.3 g of BDO, 0.45 g of Bicat3228, 32.5 g of HDI, 40.5 g of TDI, and 72 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlets and outlets. The mixture was stirred at 70 °C until the -NCO reached 1.22 wt%.

[0091] (2) The system was cooled to 50 °C and diluted with 485 g of acetone. Then it was cooled to 35 °C again. 2.31 g of triethylamine was added for neutralization under stirring, and the reaction was carried out for 10 min. Then, 580 g of deionized water was added for dispersion within 10 min under stirring at a speed of 1200 revolutions to obtain a polyurethane emulsion.

[0092] (3) 47 g of an aqueous solution of N-(2-hydroxyethyl)-ethylenediamine (concentration 15 wt%) was added to the above-mentioned polyurethane emulsion after dispersion for chain extension reaction. After the reaction ended, acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0093] After testing, the solid content of the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 200 nm.

[0094] Comparative Example 2

[0095] The preparation method of the aqueous polyurethane dispersion described in this comparative example includes the following steps:

[0096] (1) Under nitrogen protection, 130 g of polyether polyol I, 260 g of polyether polyol II, 10 g of DMPA, 8.3 g of BDO, 0.41 g of Bicat3228, 32.5 g of HDI, 40.5 g of TDI, and 72 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlets and outlets. The mixture was stirred at 70 °C until the -NCO reached 1.12 wt%, and the reaction was stopped.

[0097] (2) The reaction system was cooled to 50 °C and diluted with 482 g of acetone. Then it was cooled to 35 °C again. 2.51 g of triethylamine was added for neutralization under stirring, and the reaction was carried out for 10 min. Then, 580 g of deionized water was added for dispersion within 10 min under stirring at a speed of 1200 revolutions to obtain a polyurethane emulsion.

[0098] (3) 44 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) was added to the polyurethane emulsion after dispersion was completed for chain extension reaction, and then acetone was separated by distillation to obtain a solvent-free aqueous polyurethane dispersion.

[0099] After testing, the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 195 nm.

[0100] Comparative Example 3

[0101] The preparation method of the aqueous polyurethane dispersion in this example included the following steps:

[0102] (2) Under nitrogen protection, 130 g of polyether polyol I, 260 g of polyether polyol II, 10 g of DMPA, 8.3 g of BDO, 0.41 g of Bicat3228, 32.5 g of HDI, 40.5 g of TDI, and 72 g of acetone were added to a 1 L four-necked round-bottom flask equipped with nitrogen inlet and outlet, and the mixture was stirred at 70 °C until the -NCO reached 1.12 wt%, then the reaction was stopped;

[0103] (2) The reaction system was cooled to 50 °C and diluted with 482 g of acetone, then cooled to 35 °C again. 2.51 g of triethylamine was added under stirring for neutralization, and the reaction was carried out for 10 min under stirring. Then, 580 g of deionized water was added for dispersion within 10 min under stirring at a speed of 1200 revolutions to obtain a polyurethane emulsion;

[0104] (3) 44 g of an aqueous solution of N-(2-hydroxyethyl)ethylenediamine (concentration: 15 wt%) was added to the above-mentioned polyurethane emulsion after dispersion was completed for chain extension reaction. After the reaction ended, acetone was separated by distillation, and at the same time, 7.2 g of an organic fungicide was added and dispersed evenly to obtain a solvent-free aqueous polyurethane dispersion.

[0105] After testing, the solid content in the aqueous polyurethane dispersion was 50 wt%, and the average particle size was 195 nm.

[0106] Comparative Example 4

[0107] The preparation method of the polyurethane dispersion in this comparative example was the same as that of Example 1, and the difference was only that chitosan was used instead of the citric acid. Although the product had an antibacterial effect due to the antibacterial properties of chitosan, due to the structural characteristics of the multi-hydroxyl groups of chitosan, it was easy to cause the viscosity of the prepolymer to be too high and difficult or impossible to disperse, and it could not be directly used as a chain extender or capping agent for the aqueous polyurethane system. Therefore, the scheme of this comparative example could not obtain the expected product, and the antibacterial performance of the product failed relatively quickly.

[0108] Experimental Example Antibacterial Test

[0109] According to the above antibacterial test methods respectively, the polyurethane dispersions prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to antibacterial experiments, and the test results are shown in Table 1 below.

[0110] Table 1 Antibacterial Test Results

[0111] Sample Bacterial survival rate / % Example 1 8 Example 2 10 Example 3 13 Example 4 12 Example 5 9 Example 6 11 Comparative Example 1 89 Comparative Example 2 87 Comparative Example 3 13

[0112] From the results of the above antibacterial experiments, it can be seen that Examples 1-6 all have very obvious antibacterial effects. Taking the solution of Example 4 as an example, compared with the solutions of Comparative Examples 1 and 2, since the antibacterial capping agent citric acid was not used in Comparative Examples 1-2, the antibacterial effect of the product is extremely poor; while compared with the solution of Comparative Example 3, the antibacterial effect of the polyurethane product of the present invention is comparable, but since Comparative Example 3 uses an externally added antibacterial agent, it has a good antibacterial effect in the initial stage of dispersion production. As time goes by, the externally added bactericide will gradually fail and cannot achieve long-term antibacterial effects. At the same time, the externally added organic bactericide has certain toxicity and sensitization, which is greatly harmful to the human body.

[0113] Therefore, the inherently antibacterial polyurethane dispersion prepared by the method described in this patent can achieve excellent antibacterial effects without adding bactericides, and can be widely applied in application fields such as water-based adhesives, coatings and inks.

[0114] Obviously, the above examples are only examples clearly described and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A bio-based antibacterial aqueous polyurethane dispersion, characterized in that It comprises the following raw material components in parts by weight: 265 parts by weight of polyol, 72 parts by weight of diisocyanate, 5 parts by weight of hydrophilic chain extender, 7.2 parts by weight of neutralizer, 12 parts by weight of antibacterial capping agent, 6 parts by weight of alcohol chain extender, 30 parts by weight of amine chain extender, 0.36 part by weight of catalyst; or, 450 parts by weight of polyol, 95.3 parts by weight of diisocyanate, 11.3 parts by weight of hydrophilic chain extender, 7.2 parts by weight of neutralizer, 11 parts by weight of antibacterial capping agent, 5.95 parts by weight of alcohol chain extender, 50 parts by weight of amine chain extender, 0.6 part by weight of catalyst; or, 380 parts by weight of polyol, 70.5 parts by weight of diisocyanate, 14 parts by weight of hydrophilic chain extender, 6.52 parts by weight of neutralizer, 8 parts by weight of antibacterial capping agent, 8.3 parts by weight of alcohol chain extender, 44 parts by weight of amine chain extender, 0.5 part by weight of catalyst; or, 380 parts by weight of polyol, 73 parts by weight of diisocyanate, 14 parts by weight of hydrophilic chain extender, 6.52 parts by weight of neutralizer, 8 parts by weight of antibacterial capping agent, 8.3 parts by weight of alcohol chain extender, 40 parts by weight of amine chain extender, 0.5 part by weight of catalyst; or, 252 parts by weight of polyol, 78 parts by weight of diisocyanate, 10 parts by weight of hydrophilic chain extender, 7.2 parts by weight of neutralizer, 18 parts by weight of antibacterial capping agent, 2 parts by weight of alcohol chain extender, 30 parts by weight of amine chain extender, 0.36 part by weight of catalyst; or, 450 parts by weight of polyol, 40 parts by weight of diisocyanate, 4 parts by weight of hydrophilic chain extender, 6.52 parts by weight of neutralizer, 5 parts by weight of antibacterial capping agent, 1 part by weight of alcohol chain extender, 40 parts by weight of amine chain extender, 0.5 part by weight of catalyst; The antibacterial capping agent comprises citric acid; The polyol comprises one or a mixture of several of polyester polyol or polyether polyol; The preparation method of the bio-based antibacterial aqueous polyurethane dispersion comprises the following steps: (1) Under an inert atmosphere, a selected amount of the polyol, alcohol chain extender, diisocyanate, hydrophilic chain extender, and antibacterial capping agent are mixed evenly and subjected to a polymerization reaction until the NCO content reaches the theoretical value to obtain an isocyanate group-terminated prepolymer; (2) A polar aprotic solvent is added to the isocyanate group-terminated prepolymer for dilution, and a selected amount of the neutralizer is added for a neutralization reaction, and then water is added for dispersion to obtain a polyurethane emulsion; (3) An aqueous solution of a selected amount of the amine chain extender is added to the polyurethane emulsion for a chain extension reaction to obtain the required aqueous polyurethane dispersion.

2. The bio-based antibacterial aqueous polyurethane dispersion according to claim 1, wherein The hydrophilic chain extender comprises bisphenolic acid, or a mixture of bisphenolic acid and dimethylolpropionic acid and / or dimethylolbutyric acid.

3. The bio-based antibacterial aqueous polyurethane dispersion according to claim 1 or 2, characterized in that: The diisocyanate includes one or a mixture of several of tetramethylene diisocyanate, methyl pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclopropylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'- and 2,4'-diphenylmethane diisocyanate, tetramethylxylene diisocyanate, p-phenylene dimethyl diisocyanate or p-isopropylidene diisocyanate; The neutralizing agent includes one or a mixture of several of triethylamine, ammonia water or sodium hydroxide; The alcohol chain extender includes one or a mixture of several of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-dihydroxycyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol or 2-ethyl-1,3-hexanediol; The amine chain extender includes one or a mixture of several of 1,2-ethylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, isophorone diamine, 4,4-diaminodicyclohexylmethane or piperazine; The catalyst includes one or a mixture of several of organic zinc, organic bismuth or organic tin catalysts.

4. A method for preparing the bio-based antibacterial aqueous polyurethane dispersion according to any one of claims 1-3, characterized in that, It includes the following steps: (1) Under an inert atmosphere, a selected amount of the polyol, alcohol chain extender, diisocyanate, hydrophilic chain extender, and antibacterial capping agent are mixed evenly and subjected to a polymerization reaction until the NCO content reaches the theoretical value to obtain a terminal isocyanate group prepolymer; (2) A polar aprotic solvent is added to the terminal isocyanate group prepolymer for dilution, and a selected amount of the neutralizing agent is added for a neutralization reaction, and then water is added for dispersion to obtain a polyurethane emulsion; (3) An aqueous solution of a selected amount of the amine chain extender is added to the polyurethane emulsion for a chain extension reaction to obtain the required aqueous polyurethane dispersion.

5. The preparation method of the bio-based antibacterial aqueous polyurethane dispersion according to claim 4, characterized in that, The polar aprotic solvent includes at least one of acetone, methyl ethyl ketone, tert-butyl methyl ether or tetrahydrofuran.

6. The preparation method of the bio-based antibacterial aqueous polyurethane dispersion according to claim 5, wherein, In the step (1), a step of adding part of the polar aprotic solvent is further included.

7. The preparation method of the bio-based antibacterial aqueous polyurethane dispersion according to claim 6, wherein In the step (1), the addition amount of the polar aprotic solvent accounts for ≤25% of the total amount of the polar aprotic solvent used.

8. The preparation method of the bio-based antibacterial aqueous polyurethane dispersion according to any one of claims 4-7, characterized in that: In the step (1), the temperature of the polymerization reaction is 70-90°C; and / or, In the step (2), the addition temperature of the polar aprotic solvent is 20-60°C; and / or, In the step (2), the addition temperature of the neutralizing agent is 10-38°C; and / or, In the step (3), the temperature of the chain extension reaction is 20-50 °C.

9. The preparation method of the bio-based antibacterial aqueous polyurethane dispersion according to any one of claims 4-7, characterized in that, In the step (3), it further includes the step of partially or completely removing the polar aprotic solvent after the reaction ends.

10. Application of the bio-based antibacterial aqueous polyurethane dispersion according to any one of claims 1-3 or the bio-based antibacterial aqueous polyurethane dispersion prepared by the method according to any one of claims 4-9 in the fields of coatings, adhesives or inks.