A method for preparing an antimicrobial aqueous isocyanate curing agent

Abstract

The application discloses a preparation method of an antibacterial waterborne isocyanate curing agent, and comprises the following steps: S1, polyethylene glycol 400 and p-toluenesulfonyl chloride are added into tetrahydrofuran to prepare an intermediate a; an acetonitrile solution of the intermediate a and an acetonitrile solution of triphenylphosphine are respectively added into three-necked flasks, the temperature is raised to 80 DEG C under a nitrogen atmosphere, reflux reaction is carried out for 5 days, the temperature is recovered to room temperature after the reaction is completed, acetonitrile is removed by concentration and the three-necked flasks are washed with petroleum ether three times, petroleum ether is removed, and vacuum drying is carried out for 24 hours to prepare an intermediate 2; HDI trimer and the intermediate 2 are added into a three-necked flask, triethylamine is slowly added dropwise, the temperature is cooled to room temperature after the reaction is completed, and the product is discharged to prepare the antibacterial waterborne isocyanate curing agent; the curing agent is endowed with excellent hydrophilic performance and antibacterial performance by introducing hydrophilic sulfonic acid groups and quaternary phosphonium salt structures into the structure.

Description

Technical Field

[0001] The present invention relates to the technical field of coating curing agents, and in particular to a method for preparing an antibacterial water-based isocyanate curing agent. Background Art

[0002] Two-component waterborne polyurethane coatings are composed of a waterborne hydroxyl resin and a waterborne polyisocyanate curing agent. The performance of the waterborne polyisocyanate curing agent is crucial. Its hydrophilicity, storage stability, and compatibility with the waterborne hydroxyl resin determine the performance and application of two-component waterborne polyurethane coatings. Although traditional waterborne polyisocyanate curing agents have low viscosity and high NCO content, they lack hydrophilicity and cannot be emulsified and dispersed by the waterborne hydroxyl resin. This results in coating defects such as poor appearance, poor media resistance, low gloss, and low hardness.

[0003] Waterborne polyisocyanate curing agents can be mainly divided into nonionic and anionic waterborne polyisocyanate curing agents; nonionic waterborne polyisocyanate curing agents are usually modified by modifiers containing nonionic hydrophilic groups such as alkoxy groups, and most of them are hydrophilic polyether modified; however, a large amount of polyether is introduced during the modification process, and the resulting curing agent system has high viscosity and low NCO content. Excessive introduction of hydrophilic polyether soft segments also leads to defects such as slow drying speed, poor water resistance and low hardness of the coating; anionic waterborne polyisocyanate curing agents are usually modified by modifiers containing ionic hydrophilic groups such as sulfonate, carboxylate and phosphate groups, among which sulfonic acid groups have the strongest hydrophilicity and the best modification effect, but the hydrophilically modified waterborne polyisocyanate curing agent does not have excellent antibacterial properties, so how to improve the hydrophilicity and antibacterial properties of isocyanate curing agents is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing an antibacterial water-based isocyanate curing agent.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing an antibacterial water-based isocyanate curing agent comprises the following steps:

[0007] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass aqueous solution of potassium hydroxide was slowly added dropwise under an ice-water bath. The reaction progress was monitored by TLC after the addition was completed. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a;

[0008] In step S1, potassium hydroxide is used as an acid-binding agent, and polyethylene glycol 400 and p-toluenesulfonyl chloride react to form intermediate a. The reaction process is as follows:

[0009]

[0010] Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2;

[0011] In step S2, intermediate a reacts with triphenylphosphine to obtain intermediate 2. The reaction process is as follows:

[0012]

[0013] Step S3, adding the HDI trimer and intermediate 2 into a three-necked flask, heating to 45°C, stirring at a speed of 100 rpm for 15 min, then heating to 90°C, increasing the speed to 200 rpm, slowly adding triethylamine dropwise, and keeping the temperature to react for 6 h. After the reaction is completed, cooling to room temperature and discharging the material to obtain an antibacterial water-based isocyanate curing agent;

[0014] In step S3, an isocyanate group on the HD I trimer reacts with a hydroxyl group on the intermediate 2, introducing a hydrophilic sulfonic acid group into the structure and a quaternary phosphonium salt structure, thereby imparting excellent antibacterial properties to the curing agent.

[0015] Furthermore, in step S1, the dosage ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution and tetrahydrofuran is controlled to be 5-10 mmol: 5-10 mmol: 100 mL: 100 mL.

[0016] Furthermore, the acetonitrile solution of intermediate a in step S2 is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.50-2.52 g: 2 mL.

[0017] Furthermore, the acetonitrile solution of triphenylphosphine in step S2 is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.63-2.65 g: 20 mL.

[0018] Furthermore, in step S3, the molar ratio of the isocyanate groups on the HD I trimer to the hydroxyl groups on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine used is 30-50% of the weight of the intermediate.

[0019] Beneficial effects of the present invention:

[0020] The present invention prepares an antibacterial water-based isocyanate curing agent. Polyethylene glycol 400 and p-toluenesulfonyl chloride are reacted to generate an intermediate a. The intermediate a is then reacted with triphenylphosphine to obtain an intermediate 2. Structurally, a quaternary phosphonium salt structure is introduced into the intermediate 2, which can impart excellent antibacterial properties to the intermediate 2. The intermediate 2 is then reacted with an HDI trimer, and an isocyanate group on the HDI trimer reacts with a hydroxyl group on the intermediate 2 to prepare an isocyanate curing agent. By introducing a hydrophilic sulfonic acid group and a quaternary phosphonium salt structure into the curing agent's structure, the curing agent is endowed with both excellent hydrophilic properties and antibacterial properties. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in 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 any creative efforts are within the scope of protection of the present invention.

[0022] Example 1

[0023] A method for preparing an antibacterial water-based isocyanate curing agent comprises the following steps:

[0024] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass aqueous solution of potassium hydroxide was slowly added dropwise under an ice-water bath. After the addition was completed, the reaction progress was monitored by TLC. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a. The amount ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution, and tetrahydrofuran was controlled to be 5 mmol: 5 mmol: 100 mL: 100 mL;

[0025] Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2;

[0026] The acetonitrile solution of intermediate a is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.50 g:2 mL;

[0027] The acetonitrile solution of triphenylphosphine is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.63 g:20 mL.

[0028] Step S3: Add the HDI trimer and intermediate 2 to a three-necked flask, heat to 45°C, stir at 100 rpm for 15 min, then heat to 90°C, increase the speed to 200 rpm, slowly add triethylamine dropwise, and keep the mixture for 6 h. After the reaction is completed, cool to room temperature and discharge the mixture to obtain an antibacterial water-based isocyanate curing agent. The molar ratio of the isocyanate group on the HDI trimer to the hydroxyl group on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine is 30% of the weight of the intermediate.

[0029] Example 2

[0030] A method for preparing an antibacterial water-based isocyanate curing agent comprises the following steps:

[0031] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass potassium hydroxide aqueous solution was slowly added dropwise under an ice-water bath. After the addition was completed, the reaction progress was monitored by TLC. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a. The dosage ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution, and tetrahydrofuran was controlled to be 6 mmol: 6 mmol: 100 mL: 100 mL;

[0032] Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2;

[0033] The acetonitrile solution of intermediate a is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.51 g:2 mL;

[0034] The acetonitrile solution of triphenylphosphine is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.64 g:20 mL.

[0035] Step S3: Add the HDI trimer and intermediate 2 to a three-necked flask, heat to 45°C, stir at 100 rpm for 15 min, then heat to 90°C, increase the speed to 200 rpm, slowly add triethylamine dropwise, and keep the mixture for 6 h. After the reaction is completed, cool to room temperature and discharge the mixture to obtain an antibacterial water-based isocyanate curing agent. The molar ratio of the isocyanate group on the HDI trimer to the hydroxyl group on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine used is 35% of the weight of the intermediate.

[0036] Example 3

[0037] A method for preparing an antibacterial water-based isocyanate curing agent comprises the following steps:

[0038] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass potassium hydroxide aqueous solution was slowly added dropwise under an ice-water bath. After the addition was completed, the reaction progress was monitored by TLC. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a. The dosage ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution, and tetrahydrofuran was controlled to be 8 mmol:8 mmol:100 mL:100 mL;

[0039] Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2;

[0040] The acetonitrile solution of intermediate a is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.52 g:2 mL;

[0041] The acetonitrile solution of triphenylphosphine is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.65 g:20 mL.

[0042] Step S3: Add the HDI trimer and intermediate 2 to a three-necked flask, heat to 45°C, stir at 100 rpm for 15 min, then heat to 90°C, increase the speed to 200 rpm, slowly add triethylamine dropwise, and keep the mixture for 6 h. After the reaction is completed, cool to room temperature and discharge the mixture to obtain an antibacterial water-based isocyanate curing agent. The molar ratio of the isocyanate group on the HDI trimer to the hydroxyl group on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine is 45% of the weight of the intermediate.

[0043] Example 4

[0044] A method for preparing an antibacterial water-based isocyanate curing agent comprises the following steps:

[0045] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass aqueous solution of potassium hydroxide was slowly added dropwise under an ice-water bath. After the addition was completed, the reaction progress was monitored by TLC. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a. The amount ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution, and tetrahydrofuran was controlled to be 10 mmol: 10 mmol: 100 mL: 100 mL;

[0046] Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2;

[0047] The acetonitrile solution of intermediate a is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.52 g:2 mL;

[0048] The acetonitrile solution of triphenylphosphine is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.65 g:20 mL.

[0049] Step S3: Add the HDI trimer and intermediate 2 to a three-necked flask, heat to 45°C, stir at 100 rpm for 15 min, then heat to 90°C, increase the speed to 200 rpm, slowly add triethylamine dropwise, and keep the mixture for 6 h. After the reaction is completed, cool to room temperature and discharge the mixture to obtain an antibacterial water-based isocyanate curing agent. The molar ratio of the isocyanate group on the HDI trimer to the hydroxyl group on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine is 50% of the weight of the intermediate.

[0050] Comparative Example 1

[0051] Compared with Example 1, this comparative example does not introduce triphenylphosphine into the intermediate a. The preparation method is as follows:

[0052] Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass aqueous solution of potassium hydroxide was slowly added dropwise under an ice-water bath. After the addition was completed, the reaction progress was monitored by TLC. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a. The amount ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution, and tetrahydrofuran was controlled to be 5 mmol: 5 mmol: 100 mL: 100 mL;

[0053] HDI trimer and intermediate a were added to a three-necked flask, heated to 45°C, stirred at 100 rpm for 15 min, then heated to 90°C, the speed was increased to 200 rpm, triethylamine was slowly added dropwise, and the mixture was kept warm for 6 h. After the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a water-based isocyanate curing agent. The molar ratio of the isocyanate group on the HDI trimer to the hydroxyl group on the intermediate a was controlled to be 1:1, and the amount of triethylamine used was 30% of the weight of the intermediate.

[0054] Comparative Example 2

[0055] This comparative example is an isocyanate curing agent produced by a commercially available company.

[0056] The isocyanate curing agents prepared in Example 1 and Comparative Examples 1-2 were mixed with a water-based hydroxyl resin (hydroxyl value 2.1%) at an NCO / OH molar ratio of 1.1:1 to prepare polyurethane coatings. The performance tests were conducted. The results are shown in Table 1 below.

[0057] The specific steps for preparing the polyurethane coating are as follows: weigh the water-based hydroxyl resin and put it into a dispersion barrel, add 0.3wt% of defoamer (Foamde S92 water-based defoamer), 0.3wt% of leveling agent (BYK077 / 333), 0.5wt% of thickener (DOW's thickener RM-8W), and 2wt% of film-forming agent (dipropylene glycol methyl ether / dipropylene glycol butyl ether = 1:1), disperse at 700r / min for 20min, then slowly add the isocyanate curing agent, stir for 3min, add appropriate amount of tap water if necessary, stir evenly, and filter with 240-mesh filter cloth to obtain the polyurethane coating.

[0058] Antibacterial properties: JIS / Z2801-2000 (Antibacterial processed products - Test method for antibacterial properties and antibacterial effects) (Conditions: 35°C, 90% humidity, 24 hours).

[0059] Table 1

[0060]

[0061] It can be seen from Table 1 above that the isocyanate curing agent prepared in Example 1 of the present invention has excellent antibacterial properties.

[0062] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing an antibacterial water-based isocyanate curing agent, characterized in that: The steps include: Step S1, polyethylene glycol 400 and p-toluenesulfonyl chloride were added to tetrahydrofuran, and a 15% by mass aqueous solution of potassium hydroxide was slowly added dropwise under an ice-water bath. The reaction progress was monitored by TLC after the addition was completed. After reacting for 8 hours, the aqueous phase was extracted with ether, and the organic phases were combined, washed with saturated brine, and dried over anhydrous sodium sulfate to obtain intermediate a; Step S2, adding the acetonitrile solution of intermediate a and the acetonitrile solution of triphenylphosphine into a three-necked flask respectively, heating to 80° C. under a nitrogen atmosphere, reflux reaction for 5 days, returning to room temperature after the reaction, concentrating to remove acetonitrile, washing three times with petroleum ether, removing petroleum ether, and vacuum drying for 24 hours to obtain intermediate 2; Step S3, add HDI trimer and intermediate 2 into a three-necked flask, heat to 45 ° C, stir at 100 r / min for 15 minutes, then heat to 90 ° C, increase the speed to 200 r / min, slowly add triethylamine dropwise, keep warm and react for 6 hours, cool to room temperature after the reaction is completed, discharge, and obtain an antibacterial water-based isocyanate curing agent.

2. The method for preparing an antibacterial water-based isocyanate curing agent according to claim 1, wherein: In step S1, the dosage ratio of polyethylene glycol 400, p-toluenesulfonyl chloride, potassium hydroxide aqueous solution and tetrahydrofuran is controlled to be 5-10 mmol: 5-10 mmol: 100 mL: 100 mL.

3. The method for preparing an antibacterial water-based isocyanate curing agent according to claim 1, wherein: The acetonitrile solution of intermediate a in step S2 is prepared by mixing intermediate a and anhydrous acetonitrile in a ratio of 2.50-2.52 g: 2 mL.

4. The method for preparing an antibacterial water-based isocyanate curing agent according to claim 1, wherein: The acetonitrile solution of triphenylphosphine in step S2 is prepared by mixing triphenylphosphine and anhydrous acetonitrile in a ratio of 2.63-2.65 g: 20 mL.

5. The method for preparing an antibacterial water-based isocyanate curing agent according to claim 1, wherein: In step S3, the molar ratio of the isocyanate groups on the HDI trimer to the hydroxyl groups on the intermediate 2 is controlled to be 1:1, and the amount of triethylamine used is 30-50% of the weight of the intermediate.

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