CN111234154B - Preparation method of self-repairable waterborne polyurethane - Google Patents

Abstract

The invention discloses a preparation method of self-repairable waterborne polyurethane. According to the invention, a hydrogen bond structure such as betaine zwitter-ion hydrophilic group and thiourea group/urea group with high self-repairing property is introduced into the polyurethane chain segment simultaneously in a manner of hydrogen bond group-containing hydrophilic chain extender, so that the waterborne polyurethane material with the self-repairing function is obtained simply and efficiently. The method is suitable for various different waterborne polyurethane systems and has strong universality. On the basis of the self-repairing function, compared with the existing waterborne polyurethane resin product, the waterborne polyurethane resin provided by the invention has the advantages that the good water resistance, high solid content and stability of the waterborne polyurethane product are realized more easily.

Description

Preparation method of self-repairable waterborne polyurethane

Technical Field

The invention belongs to the field of waterborne polyurethane synthesis, and particularly relates to a preparation method of self-repairable waterborne polyurethane.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Aqueous polyurethanes are new polyurethane systems in which water is used as the dispersion medium instead of an organic solvent, and are also referred to as water-dispersed polyurethanes, aqueous polyurethanes, or water-based polyurethanes. The waterborne polyurethane takes water as a solvent, and has the advantages of no pollution, safety, reliability, excellent mechanical property, good compatibility, easy modification and the like. Due to the excellent application performance, the polyurethane resin has more and more important functions in the fields of coatings, textile finishing, pigment printing, coatings, adhesives, leather and the like. With the rapid development of national construction and the continuous emergence of new fields, higher requirements are put forward on the functional development of the waterborne polyurethane. However, the aqueous polyurethane material is still inevitably easy to be damaged by external machinery in the using process, the service life of the aqueous polyurethane material is shortened, and the maintenance and replacement cost of the material is greatly increased. To solve the problem, the waterborne polyurethane material has self-repairing capability, which is a very effective solution.

Generally, introducing a structural unit with reversible dynamic reversible covalent bond or reversible noncovalent bond interaction into a polymer material chain is a main method for constructing a self-repairing polymer material. However, the existing introduction mode of introducing the self-repairing group into the waterborne polyurethane chain segment and the preparation process are complex and tedious, high in cost and low in universality; in addition, most of the existing self-repairing waterborne polyurethane has the problems of long repairing time, low repairing efficiency and the like. These problems limit the popularization and application of the self-repairing aqueous polyurethane material.

In the process of synthesizing and preparing the self-repairing type waterborne polyurethane, the introduction of a hydrophilic group and a self-repairing functional group is the key for synthesizing the self-repairing type waterborne polyurethane. How to simply and efficiently introduce hydrophilic groups and self-repairing groups into molecular chain segments of the waterborne polyurethane material is a key for preparing self-repairing waterborne polyurethane at low cost and expanding the application of the waterborne polyurethane.

Disclosure of Invention

The invention aims to: provides a preparation method of self-repairable waterborne polyurethane. The waterborne polyurethane obtained by the method has the characteristic of high self-repairing efficiency, and is simple in preparation process and low in cost. The invention adopts a mode of hydrophilic chain extender containing hydrogen bond groups to simultaneously introduce hydrophilic groups and hydrogen bond structures with high self-repairing property into polyurethane chain segments, and the waterborne polyurethane material with the self-repairing function is simply and efficiently obtained. The method is suitable for various different waterborne polyurethane systems and has strong universality. On the basis of the self-repairing function, compared with the existing waterborne polyurethane resin product, the waterborne polyurethane resin provided by the invention has the advantages that the good water resistance, high solid content and stability of the waterborne polyurethane product are realized more easily.

The object of the invention is achieved by:

A preparation method of self-repairable waterborne polyurethane comprises the following steps:

(1) mixing diisocyanate, polymer polyol and a catalyst, and reacting to obtain a polyurethane prepolymer;

(2) adding a hydrophilic chain extender containing a hydrogen bond group into the polyurethane prepolymer obtained in the step (1), adding a cosolvent according to the viscosity condition, so that the viscosity of a system product is reduced, the emulsification is facilitated, and stirring reaction is carried out to obtain an intermediate product;

the molecular structure of the hydrophilic chain extender containing the hydrogen bond group is as follows:

wherein R1 is S or O; n is an integer of 1 to 500; m is an integer of 1-10;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring, dispersing, and then carrying out reduced pressure distillation to remove the cosolvent, so as to obtain the self-repairable aqueous polyurethane dispersion liquid.

Further, the dosage of the catalyst in the step (1) is 0ppm to 1000 ppm;

the molar ratio of the diisocyanate to the polymer polyol to the hydrophilic chain extender containing hydrogen bond groups is 2: (0.2-1.8): (0.2 to 1.8);

the mass ratio of the cosolvent in the step (2) to the polyurethane prepolymer in the step (1) is (0.01-10): 1;

the using amount of the water in the step (3) enables the solid content of the final self-repairable aqueous polyurethane dispersion to be maintained between 10% and 70%.

Further, the diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, m-xylylene diisocyanate, naphthalene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate;

the polymer polyol in the step (1) is at least one of polyester polyol with the number average molecular weight of 1000-4000 g/mol, polyether polyol with the number average molecular weight of 600-3000 g/mol and polycarbonate polyol with the number average molecular weight of 800-4000 g/mol;

the catalyst in the step (1) is at least one of dibutyltin dilaurate, stannous octoate, dibutyltin didodecyl sulfide and dibutyltin diacetate;

in the step (2), the cosolvent is at least one of acetone, butanone and N-methylpyrrolidone.

Further, in the above-mentioned case,

in the step (1), the reaction temperature is 30-120 ℃, and the reaction time is 0.5-10 h.

In the step (2), the temperature of the stirring reaction is 20-90 ℃, and the time of the stirring reaction is 2-4 h

In the step (3), the stirring and dispersing time is 0.5-3 h.

The hydrophilic chain extender containing the hydrogen bond group is prepared by the following steps:

(A) Mixing N-methyl-2, 2-diaminodiethylamine, a diimidazole compound and a solvent A, and reacting for 1-48 h at the temperature of 20-40 ℃; adding sultone, and reacting for 1-48 h at 20-80 ℃ to obtain a reaction solution;

(B) adding the reaction solution obtained in the step (A) into a solvent B to separate out a precipitate; purifying and drying to obtain a hydrophilic chain extender containing hydrogen bond groups;

wherein, in the step (A),

the solvent A is at least one of dimethylformamide, dimethyl sulfoxide, methanol, ethanol, ethyl acetate, dichloromethane, dichloroethane and chloroform;

the diimidazole compound is at least one of N, N '-carbonyl diimidazole and N, N' -thiocarbonyl diimidazole;

the sultone is at least one of 1, 3-propane sultone and 1, 4-butane sultone;

the molar ratio of the N-methyl-2, 2-diaminodiethylamine to the diimidazole compound to the sultone is 2: (1-2) 1.95-2.1;

the dosage of the solvent A is 50-500 wt% of the total amount of diamine and diimidazole compounds;

in the step (B), the solvent B is at least one of diethyl ether, acetone, petroleum ether, cyclohexane, n-hexane, cyclopentane, pentane, n-heptane, n-octane and isooctane.

In order to realize that the waterborne polyurethane has a self-repairing function, the invention comprises the following steps:

the reaction of N-methyl-2, 2-diaminodiethylamine, N' -thiocarbonyldiimidazole and sultone is controlled, and a thiourea-containing group can be introduced into the hydrophilic chain extender containing a hydrogen bond group, as shown in the following;

the reaction of N-methyl-2, 2-diaminodiethylamine, N' -carbonyldiimidazole and sultone is controlled, and urea-containing groups can be introduced into the hydrophilic chain extender containing hydrogen bond groups, as shown in the following;

the reaction ratio of N-methyl-2, 2-diaminodiethylamine, N '-carbonyl diimidazole, N' -thiocarbonyl diimidazole and sultone is controlled, and urea-containing groups and thiourea groups can be simultaneously introduced into the hydrophilic chain extender containing hydrogen bond groups, as shown in the following;

the hydrophilic chain extender containing thiourea groups and urea groups and hydrogen bond groups is further reacted with the polyurethane prepolymer, so that the hydrogen bond groups such as thiourea groups and urea groups are introduced into the polyurethane polymer chain segment, and self-repair of the material is realized by means of the breakage and recombination of hydrogen bonds in molecules or between molecules, so that the polyurethane material has a better self-repair function. The principle of the hydrogen bond action inside the aqueous polyurethane material containing the thiourea group, the urea group and other hydrogen bond groups is as follows:

；

；

；

Meanwhile, the formed hydrogen bond groups such as thiourea group and urea group can also form a hydrogen bond structure with a hydrogen bond donor/acceptor (such as urethane bond and urea bond) of the waterborne polyurethane, so that the hydrogen bond function of the system is further enhanced.

In addition, a sulfonamide betaine zwitterionic group is introduced into the system through the hydrophilic chain extender containing the hydrogen bond group, on one hand, the sulfonamide betaine zwitterionic group is used as a hydrophilic group, so that the water dispersibility of the polyurethane is endowed, and the good water resistance, high solid content and stability of the waterborne polyurethane product are realized; on the other hand, the electrostatic interaction between the sulfonamide betaine zwitterionic group structures further endows the material with a better self-repairing function, as shown in the attached figure 2.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. according to the invention, a hydrogen bond structure such as betaine zwitter-ion hydrophilic group and thiourea group/urea group with high self-repairing property is introduced into the polyurethane chain segment simultaneously in a manner of hydrogen bond group-containing hydrophilic chain extender, so that the waterborne polyurethane material with the self-repairing function is obtained simply and efficiently.

2. The self-repairing efficiency of the self-repairable waterborne polyurethane is high, the preparation process is simple, and the cost is low.

3. The waterborne polyurethane prepared by the invention has an excellent self-repairing function; compared with the existing waterborne polyurethane resin product, the waterborne polyurethane resin provided by the invention has the advantages that the good water resistance, high solid content and stability of the waterborne polyurethane product are realized more easily.

Drawings

FIG. 1 is a self-healing process diagram of the self-repairable aqueous polyurethane of example 4;

FIG. 2 is a schematic diagram of the principle of electrostatic interaction presented between the sulfonamide betaine zwitterionic group structures.

Detailed Description

The following describes in detail embodiments of the present invention with reference to the drawings and examples, but the embodiments of the present invention are not limited thereto.

Example 1

(A) 234g of N-methyl-2, 2-diaminodiethylamine, 354g of N, N' -thiocarbonyldiimidazole and 500g of dimethyl sulfoxide are mixed and reacted for 24 hours at the temperature of 30 ℃; then 244g of 1, 3-propane sultone is added to react for 12 hours at the temperature of 60 ℃ to obtain reaction liquid;

(B) adding the reaction solution obtained in the step (A) into acetone to separate out a precipitate; purifying and drying to obtain a hydrophilic chain extender containing hydrogen bond groups;

the molecular structure of the obtained hydrophilic chain extender containing the hydrogen bond group is as follows:

the number average molecular weight was determined to be about 10000 g/mol.

Example 2

(A) 234g of N-methyl-2, 2-diaminodiethylamine, 324g of N, N' -carbonyldiimidazole and dimethylformamide are mixed and reacted for 1h at the temperature of 40 ℃; then 256g of 1, 3-propane sultone is added to react for 48 hours at the temperature of 20 ℃ to obtain reaction liquid;

(B) adding the reaction solution obtained in the step (A) into acetone to separate out a precipitate; purifying and drying to obtain a hydrophilic chain extender containing hydrogen bond groups;

the molecular structure of the obtained hydrophilic chain extender containing the hydrogen bond group is as follows:

the number average molecular weight was determined to be about 20000 g/mol.

Example 3

(A) 234g of N-methyl-2, 2-diaminodiethylamine, 160g of N, N '-carbonyldiimidazole, 160g of N, N' -thiocarbonyldiimidazole and 1000g of dimethyl sulfoxide are mixed and reacted at 20 ℃ for 48 hours; then adding 250g of 1, 3-propane sultone, and reacting for 1h at 80 ℃ to obtain reaction liquid;

(B) adding the reaction liquid obtained in the step (A) into petroleum ether to separate out a precipitate; purifying and drying to obtain a hydrophilic chain extender containing hydrogen bond groups;

the molecular structure of the obtained hydrophilic chain extender containing the hydrogen bond group is as follows:

it was determined that the number average molecular weight was about 8000 g/mol.

Example 4

(1) 174.15g of toluene diisocyanate, 1000g of polycaprolactone diol with the number average molecular weight of 2000g/mol and stannous octoate catalyst are mixed, the dosage of the catalyst is controlled to be 100ppm, and the polyurethane prepolymer is obtained after reaction is carried out for 8 hours at the temperature of 80 ℃;

(2) adding 5000g of the hydrophilic chain extender containing the hydrogen bond group prepared in the example (1) and 1000g of butanone into the polyurethane prepolymer obtained in the step (1), so that the viscosity of a system product is reduced, the emulsification is convenient, and an intermediate product is obtained after stirring and reacting for 2 hours at the temperature of 60 ℃;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring, dispersing for 3h, and then carrying out reduced pressure distillation to remove the cosolvent to obtain the self-repairable aqueous polyurethane dispersion liquid with the solid content of 60%.

And coating the prepared self-repairable aqueous polyurethane dispersion liquid on the surface of a substrate, and drying to obtain the self-repairable aqueous polyurethane coating. The self-repairable water-based polyurethane coating is scratched, and the material can be healed and repaired within 10 minutes. Therefore, after the contact at room temperature in a short time, efficient healing and repair can be realized.

Example 5

(1) 250.24 g of diphenylmethane diisocyanate, 300g of polytetrahydrofuran diol with the number average molecular weight of 1000g/mol and dibutyltin dilaurate catalyst are mixed, the dosage of the catalyst is controlled to be 60ppm, and the mixture reacts for 1 hour at the temperature of 90 ℃ to obtain a polyurethane prepolymer;

(2) 10000g of the hydrophilic chain extender containing hydrogen bond groups prepared in the example (2) and 100g of butanone are added into the polyurethane prepolymer obtained in the step (1), so that the viscosity of a system product is reduced, the emulsification is convenient, and an intermediate product is obtained after stirring and reacting for 4 hours at 50 ℃;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring and dispersing for 2h, and then carrying out reduced pressure distillation to remove the cosolvent to obtain the self-repairable aqueous polyurethane dispersion liquid with the solid content of 50%.

And coating the prepared self-repairable aqueous polyurethane dispersion liquid on the surface of a substrate, and drying to obtain the self-repairable aqueous polyurethane coating. The self-repairable water-based polyurethane coating is scratched, and the material can be healed and repaired within 8 minutes. Therefore, after the contact at room temperature in a short time, efficient healing and repair can be realized.

Example 6

(1) 188.2g of m-xylylene diisocyanate, 600g of polyoxypropylene glycol with the number average molecular weight of 2000g/mol and dibutyltin dilaurate catalyst are mixed, the dosage of the catalyst is controlled to be 10ppm, and the mixture reacts for 4 hours at the temperature of 80 ℃ to obtain a polyurethane prepolymer;

(2) adding 5600g of the hydrophilic chain extender containing the hydrogen bond group prepared in the example (3) and 1000g of acetone into the polyurethane prepolymer obtained in the step (1), so that the viscosity of a system product is reduced, the emulsification is facilitated, and an intermediate product is obtained after stirring and reacting for 3 hours at 50 ℃;

(3) And (3) adding water into the intermediate product obtained in the step (2), stirring and dispersing for 2h, and then carrying out reduced pressure distillation to remove the cosolvent to obtain the self-repairable aqueous polyurethane dispersion liquid with the solid content of 40%.

And coating the prepared self-repairable aqueous polyurethane dispersion liquid on the surface of a substrate, and drying to obtain the self-repairable aqueous polyurethane coating. The self-repairable water-based polyurethane coating is scratched, and the material can be healed and repaired within 1 minute. Therefore, after the contact at room temperature in a short time, efficient healing and repair can be realized.

Example 7

(1) 210.19g of naphthalene diisocyanate, 1800g of polytetrahydrofuran diol with the number average molecular weight of 2000g/mol and dibutyltin dilaurate catalyst are mixed, the dosage of the catalyst is controlled to be 1000ppm, and the mixture reacts for 0.5h at the temperature of 40 ℃ to obtain a polyurethane prepolymer;

(2) adding 100g of the hydrophilic chain extender containing the hydrogen bond group prepared in the example (1) and 20.1g of N-methyl pyrrolidone into the polyurethane prepolymer obtained in the step (1), so that the viscosity of a system product is reduced, the emulsification is convenient, and an intermediate product is obtained after stirring reaction for 2 hours at 90 ℃;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring, dispersing for 3h, and then carrying out reduced pressure distillation to remove the cosolvent to obtain the self-repairable aqueous polyurethane dispersion liquid with the solid content of 70%.

And coating the prepared self-repairable aqueous polyurethane dispersion liquid on the surface of a substrate, and drying to obtain the self-repairable aqueous polyurethane coating. The self-repairable water-based polyurethane coating is scratched, and the material can be healed and repaired within 1 minute. Therefore, after the contact at room temperature in a short time, efficient healing repair can be realized.

Example 8

(1) 188.2g of m-xylylene diisocyanate and 150g of polycaprolactone diol with the number average molecular weight of 1500g/mol are reacted for 10 hours at the temperature of 30 ℃ to obtain a polyurethane prepolymer;

(2) adding 18000g of the hydrophilic chain extender containing the hydrogen bond group prepared in the example (2) and 33800g of butanone into the polyurethane prepolymer obtained in the step (1), so that the viscosity of a system product is reduced, the emulsification is convenient, and an intermediate product is obtained after stirring and reacting for 4 hours at 20 ℃;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring, dispersing for 0.5h, and then carrying out reduced pressure distillation to remove the cosolvent to obtain the self-repairable aqueous polyurethane dispersion liquid with the solid content of 10%.

And coating the prepared self-repairable aqueous polyurethane dispersion liquid on the surface of a substrate, and drying to obtain the self-repairable aqueous polyurethane coating. The self-repairable water-based polyurethane coating is scratched, and the material can be healed and repaired within 1 minute. Therefore, after the contact at room temperature in a short time, efficient healing and repair can be realized.

The invention compares the performances of the self-repairable waterborne polyurethane coating prepared by the embodiment with the performances of the waterborne polyurethane materials on the market. Wherein the non-volatile matter is carried out according to GB/T6740; the water resistance is carried out according to GB/T1733-1993 (9.1A method and 9.2B method), GB 9755-2001; the water absorption is carried out according to HG/T3344-; the low temperature stability was carried out in accordance with GB 9755-2001 (specification 5.5); the impact resistance is carried out according to GB/T1732-93; the adhesion was carried out according to GB/T9286. The results are shown in the following table.

Surface water-based polyurethane and coating film performance thereof

The data in the table compare various performance indexes of the self-repairing waterborne polyurethane prepared by different embodiments of the invention and certain waterborne polyurethane products on the market. As can be seen from the table, in the examples (examples 4, 5, 7), the self-repairing aqueous polyurethane has a higher solid content, excellent water resistance and stability; the embodiments of the invention have better water resistance and stability than the market waterborne polyurethane material.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (5)

1. A preparation method of self-repairable waterborne polyurethane is characterized by comprising the following steps:

(1) mixing diisocyanate, polymer polyol and a catalyst, and reacting to obtain a polyurethane prepolymer;

(2) adding a hydrophilic chain extender containing a hydrogen bond group into the polyurethane prepolymer obtained in the step (1), adding a cosolvent according to the viscosity condition, so that the viscosity of a system product is reduced, the emulsification is facilitated, and stirring reaction is carried out to obtain an intermediate product;

the hydrophilic chain extender containing the hydrogen bond group has the following molecular structure:

；

wherein R1 is S or O; n is an integer of 1 to 500; m is an integer of 1-10;

(3) and (3) adding water into the intermediate product obtained in the step (2), stirring, dispersing, and then carrying out reduced pressure distillation to remove the cosolvent, so as to obtain the self-repairable aqueous polyurethane dispersion liquid.

2. The preparation method of the self-repairable aqueous polyurethane according to claim 1, wherein the preparation method comprises the following steps:

the dosage of the catalyst in the step (1) is 0ppm to 1000 ppm;

the molar ratio of the diisocyanate to the polymer polyol to the hydrophilic chain extender containing hydrogen bond groups is 2: (0.2-1.8): (0.2 to 1.8);

the mass ratio of the cosolvent in the step (2) to the polyurethane prepolymer in the step (1) is (0.01-10): 1;

The using amount of the water in the step (3) enables the solid content of the final self-repairable aqueous polyurethane dispersion to be maintained between 10% and 70%.

3. The preparation method of the self-repairable aqueous polyurethane according to claim 1, wherein the preparation method comprises the following steps:

the diisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, m-xylylene diisocyanate, naphthalene diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate;

the polymer polyol in the step (1) is at least one of polyester polyol with the number average molecular weight of 1000-4000 g/mol, polyether polyol with the number average molecular weight of 600-3000 g/mol and polycarbonate polyol with the number average molecular weight of 800-4000 g/mol;

the catalyst in the step (1) is at least one of dibutyltin dilaurate, stannous octoate, dibutyltin didodecyl sulfide and dibutyltin diacetate;

in the step (2), the cosolvent is at least one of acetone, butanone and N-methylpyrrolidone.

4. The preparation method of the self-repairable aqueous polyurethane according to claim 1, wherein the preparation method comprises the following steps:

In the step (1), the reaction temperature is 30-120 ℃, and the reaction time is 0.5-10 h;

in the step (2), the temperature of the stirring reaction is 20-90 ℃, and the time of the stirring reaction is 2-4 h;

in the step (3), the stirring and dispersing time is 0.5-3 h.

5. The preparation method of self-repairable polyurethane according to claim 1, wherein the hydrophilic chain extender containing hydrogen bond groups is prepared by the following steps:

(A) mixing N-methyl-2, 2-diaminodiethylamine, a diimidazole compound and a solvent A, and reacting for 1-48 h at the temperature of 20-40 ℃; adding sultone, and reacting for 1-48 h at 20-80 ℃ to obtain a reaction solution;

(B) adding the reaction solution obtained in the step (A) into a solvent B to separate out a precipitate; purifying and drying to obtain a hydrophilic chain extender containing hydrogen bond groups;

wherein, in the step (A),

the solvent A is at least one of dimethylformamide, dimethyl sulfoxide, methanol, ethanol, ethyl acetate, dichloromethane, dichloroethane and chloroform;

the diimidazole compound is at least one of N, N '-carbonyl diimidazole and N, N' -thiocarbonyl diimidazole;

the sultone is at least one of 1, 3-propane sultone and 1, 4-butane sultone;

The molar ratio of the N-methyl-2, 2-diaminodiethylamine to the diimidazole compound to sultone is 2: (1-2) 1.95-2.1;

the dosage of the solvent A is 50-500 wt% of the total amount of diamine and diimidazole compounds;

in the step (B), the solvent B is at least one of diethyl ether, acetone, petroleum ether, cyclohexane, n-hexane, cyclopentane, pentane, n-heptane, n-octane and isooctane.

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