Self-repairing waterborne polyurethane as well as preparation method and application thereof

Abstract

The invention discloses self-repairing waterborne polyurethane as well as a preparation method and application thereof. The polyurethane is prepared from the following raw materials through reaction: S1, one or more polyisocyanates; s2, one or more macromolecular polyols; s3, one or more micromolecule chain extenders; s4, a carboxylic acid type hydrophilic compound; S5, one or more amino-containing compounds; s6, one or more neutralizing agents; s7, water; and S8, an optional catalyst. According to the waterborne polyurethane provided by the invention, on the premise that the original performance of a polyurethane material is not influenced, a prepared waterborne polyurethane coating is endowed with continuous self-repairing performance under the mild condition without a catalyst.

Description

Technical Field

[0001] The invention relates to a waterborne polyurethane, and in particular to a self-repairing waterborne polyurethane and a preparation method and application thereof. Background Art

[0002] Waterborne polyurethane coatings are environmentally friendly, have good gloss, excellent flexibility and wear resistance, and are widely used on various substrate surfaces, such as metal, wood, plastic, and leather. However, polyurethane coatings will inevitably be stimulated by the external environment during use, resulting in cracks and damage. These defects not only affect the appearance, but also shorten its service life. Therefore, the development of waterborne polyurethane with self-healing properties is an important trend at present.

[0003] At present, waterborne polyurethane with self-healing properties is mainly achieved by introducing a dynamic reversible bond structure on the polymer molecular chain, and realizing the self-healing process through the bonding and breaking of the reversible bond. There are two types of dynamic reversible bonding, one is dynamic reversible covalent connection, such as DA reaction, disulfide exchange reaction, ester exchange, etc.; the other is dynamic reversible non-covalent connection, such as hydrogen bond, metal coordination bond, ionic bond, host-guest interaction, etc.

[0004] Patent CN114349933A discloses the invention of a self-healing waterborne polyurethane prepared by the DA reaction of furfurylamine and bismaleimide. The self-healing rate of this polyurethane material at 100°C for 8 hours is about 71%. Furfurylamine is a highly toxic substance and is environmentally unfriendly. In addition, a large amount of high-boiling point solvents are used in the synthesis of the monomer mixed solution, which limits its application range.

[0005] Patent CN117757030A provides a preparation method of a waterborne polyurethane thermal conductive self-healing material based on dynamic disulfide bonds. The dynamic disulfide bonds are introduced into the polyurethane main chain in two steps to give the material good self-healing properties. The pure polyurethane film with cracks cut can be completely healed at 40°C after 1.5 hours. However, the introduction of disulfide bonds affects the mechanical properties of the polyurethane material and reduces the tensile strength. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a self-healing waterborne polyurethane and its preparation method and application. The present invention introduces dynamically reversible covalent bonds and non-covalent bonds by compounding specific amino compounds, which can give the prepared waterborne polyurethane coating continuous self-healing properties under non-catalytic and mild conditions without affecting the original properties of the polyurethane material.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A self-repairing waterborne polyurethane is prepared by reacting the following raw materials:

[0009] S1, one or more polyisocyanates;

[0010] S2, one or more macromolecular polyols, having an average molecular weight of 500 to 5000 g / mol, preferably an average molecular weight of 1000 to 2000 g / mol;

[0011] S3, one or more small molecule chain extenders, containing at least two groups capable of reacting with isocyanate, and having a molecular weight of 60 to 499 g / mol;

[0012] S4, a carboxylic acid type hydrophilic compound,

[0013] S5, one or more amino-containing compounds;

[0014] S6, one or more neutralizing agents;

[0015] S7, water,

[0016] S8. Optionally, a catalyst.

[0017] In some preferred examples, based on the total mass of raw materials S1-S7 being 100%, the amount of each raw material is as follows:

[0018] Component S1 8.0-15.0 wt%, preferably 8.5-14.0 wt%,

[0019] Component S2 16.0-28.0 wt%, preferably 18-25.0 wt%,

[0020] Component S3 0.1-1.2 wt%, preferably 0.2-0.9 wt%,

[0021] Component S4 0.2-2.0 wt%, preferably 0.7-2.0 wt%,

[0022] Component S5 0.2-1.5 wt%, preferably 0.3-1.5 wt%,

[0023] Component S6 0.1-2.0 wt%, preferably 0.4-1.2 wt%,

[0024] Component S7 58.0-73.0 wt%, preferably 60.0-70.0 wt%,

[0025] Preferably, the amount of component S8 is 0 to 2000 ppm of the total mass of components S1 to S5.

[0026] In some preferred examples, component S1 is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, preferably one or more of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate; and / or

[0027] Preferably, component S2 is selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetramethylene glycol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, poly1,4-butylene adipate diol, polyneopentyl adipate diol, poly1,6-hexanediol adipate diol, polyneopentyl adipate 1,6-hexanediol adipate diol, preferably poly1,4-butylene adipate diol and / or polyneopentyl adipate 1,6-hexanediol adipate diol.

[0028] In some preferred examples, component S3 is selected from one or more of 1,3-propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol, preferably one or more of 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol;

[0029] Preferably, component S4 is selected from one or more of 3-hydroxypropionic acid, dimethylolpropionic acid, dimethylolbutanoic acid, and dimethylolacetic acid.

[0030] In some preferred examples, component S5 includes: a) an amine compound containing a thiourea group, including but not limited to one or more of thiourea, 1,3-diethylthiourea, N,N-di-n-butylthiourea, and 1-phenyl-3-propyl-2-thiourea; b) an amine compound containing a secondary amino group, preferably one or more of tert-butylisopropylamine, diisopropylamine, diethylamine, N,N'-di-tert-butylethylenediamine and N,N'-diisopropylethylenediamine, preferably one or more of N,N'-di-tert-butylethylenediamine and N,N'-diisopropylethylenediamine;

[0031] Preferably, the mass ratio of component a) to component b) is 0.3 to 1.0, preferably 0.5 to 0.9.

[0032] In some preferred examples, component S6 is selected from one or more of triethanolamine, triethylamine, sodium hydroxide, and N,N-dimethylethanolamine.

[0033] In some preferred examples, component S8 is an organic bismuth and / or organic tin catalyst, preferably Bi@8108 or butyltin laurate from a leading American company.

[0034] The present invention also relates to a method for preparing the self-healing waterborne polyurethane as described above, characterized in that it comprises the following steps:

[0035] 1) mixing components S1, S2, S3, S4, and optionally S8 with an organic solvent, and reacting at 75-85° C. until NCO reaches a theoretical value to obtain an NCO-terminated prepolymer;

[0036] 2) Cooling the prepolymer to 50-60°C, then adding an organic solvent to dilute it, and then adding component S5, and reacting at 45-60°C for 10-15 minutes;

[0037] 3) Component S6 and part of component S7 are mixed, added to the reaction solution obtained in step 2), reacted at 20-45° C. for 5-10 min, and then the remaining S7 is added, sheared and dispersed to obtain an emulsion, and finally the organic solvent is removed to obtain the waterborne polyurethane.

[0038] In some preferred examples, the organic solvent is selected from reaction inert solvents with a boiling point range of 40 to 85° C., preferably acetone, butanone, and the like.

[0039] In some preferred examples, the total amount of the organic solvent is 0.6 to 2.1 times the total mass of components S1 to S7.

[0040] The present invention also provides an application of the self-repairing waterborne polyurethane as described above in metal coatings, wood coatings, textile coatings, furniture coatings, and packaging coatings, and further, for example, in leather finishing agents.

[0041] The present invention introduces a thiourea bond that can form a hydrogen bond and a reversible substituted urea bond into the polyurethane segment by adjusting the raw material selection. The synergistic introduction of the two urea bonds combines covalent and non-covalent dynamic reversible methods, and can achieve self-repair of scratches, cracks and other damages under catalyst-free and mild conditions without affecting the original performance of the polyurethane material. After the coating of the present invention is scratched, after 8 hours at 40°C, the repair rate is about 95%, and the raw materials used are easily available, the process is simple, and it is easy to operate. DETAILED DESCRIPTION

[0042] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0043] 1. Main raw material sources of embodiments:

[0044] Polytetrahydrofuran: functionality 2, molecular weight 2000 g / mol, BASF GmbH;

[0045] Polycaprolactone diol: number average molecular weight 1000, Daicel Trading (Shanghai) Co., Ltd.;

[0046] 4,4'-Dicyclohexylmethane diisocyanate (HMDI): industrial grade, Wanhua Chemical Group Co., Ltd.;

[0047] Isophorone diisocyanate (IPDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0048] Hexamethylene diisocyanate (HDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0049] Catalyst: Bi@8108, Leading Technologies, Inc.

[0050] Dimethylolpropionic acid (DMPA): technical grade, Perstorp Chemical Company;

[0051] 1,4-Butanediol: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0052] Neopentyl glycol: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0053] Trihydroxymethylpropane: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0054] Acetone: industrial grade, Wanhua Chemical Group Co., Ltd.;

[0055] Thiourea: analytical grade, MacLean Reagent Co., Ltd.;

[0056] 1,3-Diethylthiourea: analytical grade, MacLean Reagent Co., Ltd.;

[0057] N,N-Di-n-butylthiourea: analytical grade, MacLean Reagent Co., Ltd.;

[0058] N,N'-di-tert-butylethylenediamine: analytical grade, MacLean Reagent Co., Ltd.;

[0059] N,N'-Diisopropylethylenediamine: analytical grade, MacLean Reagent Co., Ltd.;

[0060] Tert-butylisopropylamine: analytical grade, MacLean Reagent Co., Ltd.;

[0061] Diisopropylamine: analytical grade, MacLean Reagent Co., Ltd.;

[0062] Isophorone diamine: industrial grade, Wanhua Chemical Group Co., Ltd.

[0063] Triethylamine: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0064] Other raw materials were purchased from the market unless otherwise specified.

[0065] 2. Performance test method:

[0066] Particle size testing method: Malvern particle size analyzer was used.

[0067] Emulsion stability: Observe the emulsion with naked eyes to see if there is precipitation.

[0068] Mechanical properties test method: GB / T13022-1991;

[0069] Heat resistance: 20um wire rod is used to scrape PVC leather, dried at 100 degrees for about 1 minute, cut into 5*5cm, and pasted. 80℃ / 3kg / 24h, if there is no adhesion after peeling off, it is heat resistance. 1-5 levels, 1 is very severe adhesion, 5 is no adhesion.

[0070] Adhesion test method: 20um wire rod is used to scrape PVC leather, and then dried at 100 degrees for about 1 minute. The national standard GB / T9286-1998 is adopted.

[0071] Repair efficiency: After damage, the sample was placed at 40℃ for 8 hours and then the scratch repair was observed.

[0072] Example 1

[0073] 10g HDI, 38g IPDI, 58g polytetrahydrofurandiol, 43g polycaprolactone, 3.6g neopentyl glycol, 0.4g trimethylolpropane, 5.4g dimethylolpropionic acid, 0.07g catalyst and 65g acetone were added to a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 80°C until the NCO reached 2.6wt%. The mixture was cooled to 55°C and diluted with 240g acetone, and then 3.5g N,N-di-tert-butylethylenediamine, 1g tert-butylisopropylamine and 2.4g thiourea were added to extend the chain at 50°C for 15min. Then 4g triethylamine was added and neutralized at room temperature for 10min, and then 330g deionized water was slowly added to the system. After dispersion and stirring for 15min, a dispersion was obtained. After removing acetone using a rotary evaporator, a waterborne polyurethane was obtained.

[0074] Example 2

[0075] 25g HMDI, 21g IPDI, 72g polytetrahydrofuran diol, 36g polycaprolactone, 1.5g 1,4-butanediol, 4.5g dimethylol propionic acid, 0.07g catalyst and 65g acetone were added to a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 80°C until the NCO reached 2.6wt%. The mixture was cooled to 55°C and diluted with 240g acetone, and then 2.45g N,N-diisopropylethylenediamine and 2.2g thiourea were added to extend the chain at 50°C for 15min. Then 3.3g triethylamine was added and neutralized at room temperature for 10min, and then 330g deionized water was slowly added to the system. After dispersion and stirring for 15min, a dispersion was obtained. After removing acetone using a rotary evaporator, a waterborne polyurethane was obtained.

[0076] Example 3

[0077] 26g HMDI, 16g HDI, 74g polytetrahydrofuran diol, 37g polycaprolactone, 2.0g 1,4-butanediol, 0.4g trimethylolpropane, 4.6g dimethylolpropionic acid, 0.07g catalyst and 65g acetone were added to a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 80°C until the NCO reached 2.6wt%. The mixture was cooled to 55°C and 240g acetone was added for dilution, and then 2.9g N,N-di-tert-butylethylenediamine, 1g diisopropylamine, 2.8g N,N-di-n-butylthiourea and 0.4g thiourea were added for chain extension reaction at 50°C for 15min. Then 3.4g triethylamine was added for neutralization at room temperature for 10min, and 330g deionized water was slowly added to the system. After dispersion and stirring for 15min, a dispersion was obtained. After removing acetone using a rotary evaporator, a waterborne polyurethane was obtained.

[0078] Example 4

[0079] 46g HMDI, 6g IPDI, 75g polytetrahydrofuran diol, 25g polycaprolactone, 1.6g 1,4-butanediol, 0.7g trimethylolpropane, 6.0g dimethylolpropionic acid, 0.07g catalyst and 65g acetone were added to a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 80°C until the NCO reached 2.6wt%. The mixture was cooled to 55°C and diluted with 240g acetone, and then 2.2g N,N-diisopropylethylenediamine, 1.7g tert-butylisopropylamine and 1.7g thiourea were added to extend the chain at 50°C for 15min. Then 3.4g triethylamine was added and neutralized at room temperature for 10min, and then 330g deionized water was slowly added to the system. After dispersion and stirring for 15min, a dispersion was obtained. After removing acetone using a rotary evaporator, a waterborne polyurethane was obtained.

[0080] Example 5

[0081] 6g HMDI, 38g IPDI, 73g polytetrahydrofurandiol, 36g polycaprolactone, 1.5g 1,4-butanediol, 0.3g trimethylolpropane, 4.6g dimethylolpropionic acid, 0.07g catalyst and 65g acetone were added to a 1L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and the mixture was stirred at 80°C until the NCO reached 2.6wt%. The mixture was cooled to 55°C and 240g acetone was added for dilution, and then 3.3g N,N-di-tert-butylethylenediamine, 0.7g N,N-diisopropylethylenediamine and 2.9g 1,3-diethylthiourea were added for chain extension reaction at 50°C for 15min. Then 3.4g triethylamine was added for neutralization at room temperature for 10min, and 330g deionized water was slowly added to the system. After dispersion and stirring for 15min, a dispersion was obtained. After removing acetone using a rotary evaporator, a waterborne polyurethane was obtained.

[0082] Comparative Example 1

[0083] Aqueous polyurethane was prepared in substantially the same manner as in Example 2, except that 2.45 g of N,N-diisopropylethylenediamine and 2.2 g of thiourea were replaced with 4.65 g of isophoronediamine.

[0084] Comparative Example 2

[0085] Aqueous polyurethane was prepared in substantially the same manner as in Example 2, except that 2.45 g of N,N-diisopropylethylenediamine and 2.2 g of thiourea were replaced with 5.7 g of N,N-diisopropylethylenediamine and 1.3 g of thiourea.

[0086] Comparative Example 3

[0087] Aqueous polyurethane was prepared in substantially the same manner as in Example 2, except that 2.45 g of N,N-diisopropylethylenediamine and 2.2 g of thiourea were replaced with 2.1 g of N,N-diisopropylethylenediamine and 2.6 g of thiourea.

[0088] The waterborne polyurethane prepared in the above examples and comparative examples was tested for the properties shown in Table 1, and the results were as follows:

[0089] Table 1. Performance test results

[0090]

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this field can make several improvements and supplements without departing from the method of the present invention. These improvements and supplements should also be regarded as the scope of protection of the present invention.

Claims

1. A self-repairing waterborne polyurethane, characterized in that: The method comprises reacting the following raw materials: S1, one or more polyisocyanates; S2, one or more macromolecular polyols having an average molecular weight of 500 to 5000 g / mol, preferably an average molecular weight of 1000 to 2000 g / mol; S3, one or more small molecule chain extenders, containing at least two groups reactive with isocyanate, and having a molecular weight of 60 to 499 g / mol; S4, a carboxylic acid type hydrophilic compound, S5, one or more amino-containing compounds; S6, one or more neutralizing agents; S7, water, S8. Optionally, a catalyst.

2. The self-repairing waterborne polyurethane according to claim 1, characterized in that: Taking the total mass of raw materials S1-S7 as 100%, the amount of each raw material used is as follows: Component S1 8.0-15.0 wt%, preferably 8.5-14.0 wt%, Component S2 16.0-28.0 wt%, preferably 18-25.0 wt%, Component S3 0.1-1.2 wt%, preferably 0.2-0.9 wt%, Component S4 0.2~2.0wt%, preferably 0.7~2.0wt%, Component S5 0.2~1.5wt%, preferably 0.3~1.5wt%, Component S6 0.1-2.0 wt%, preferably 0.4-1.2 wt%, Component S7 58.0-73.0 wt%, preferably 60.0-70.0 wt%, Preferably, the amount of component S8 is 0 to 2000 ppm of the total mass of components S1 to S5.

3. The self-repairing waterborne polyurethane according to claim 1 or 2, characterized in that: Component S1 is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, preferably one or more of isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate; and / or Preferably, component S2 is selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetramethylene ether glycol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, poly1,4-butylene adipate diol, polyneopentyl adipate diol, poly1,6-hexanediol adipate diol, polyneopentyl adipate 1,6-hexanediol adipate diol, preferably poly1,4-butylene adipate diol and / or polyneopentyl adipate 1,6-hexanediol adipate diol.

4. The self-repairing waterborne polyurethane according to any one of claims 1 to 3, characterized in that: Component S3 is selected from one or more of 1,3-propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol, preferably one or more of 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; Preferably, component S4 is selected from one or more of 3-hydroxypropionic acid, dimethylolpropionic acid, dimethylolbutanoic acid, and dimethylolacetic acid.

5. The self-repairing waterborne polyurethane according to any one of claims 1 to 4, characterized in that: Component S5 includes: a) an amine compound containing a thiourea group, including but not limited to one or more of thiourea, 1,3-diethylthiourea, N,N-di-n-butylthiourea, and 1-phenyl-3-propyl-2-thiourea; b) an amine compound containing a secondary amino group, preferably one or more of tert-butylisopropylamine, diisopropylamine, diethylamine, N,N'-di-tert-butylethylenediamine and N,N'-diisopropylethylenediamine, preferably one or more of N,N'-di-tert-butylethylenediamine and N,N'-diisopropylethylenediamine; Preferably, the mass ratio of component a) to component b) is 0.3 to 1.0, preferably 0.5 to 0.

9.

6. The self-repairing waterborne polyurethane according to any one of claims 1 to 5, characterized in that: Component S6 is selected from one or more of triethanolamine, triethylamine, sodium hydroxide, and N,N-dimethylethanolamine.

7. The self-repairing waterborne polyurethane according to any one of claims 1 to 6, characterized in that: Component S8 is an organic bismuth and / or organic tin catalyst, preferably Bi@8108 or butyltin laurate from a leading American company.

8. A method for preparing the self-repairing waterborne polyurethane according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) mixing components S1, S2, S3, S4, and optionally S8 with an organic solvent, and reacting at 75-85° C. until the NCO content reaches a theoretical value to obtain an NCO-terminated prepolymer; 2) Cooling the prepolymer to 50-60°C, then adding an organic solvent to dilute it, and then adding component S5, and reacting at 45-60°C for 10-15 minutes; 3) Component S6 and part of component S7 are mixed and added to the reaction solution obtained in step 2), reacted at 20-45° C. for 5-10 minutes, and then the remaining S7 is added and sheared and dispersed to obtain an emulsion. Finally, the organic solvent is removed to obtain the waterborne polyurethane.

9. The method for preparing the self-repairing waterborne polyurethane according to any one of claims 1 to 7, characterized in that: The total amount of the organic solvent is 0.6 to 2.1 times the total mass of components S1 to S7.

10. Use of the self-healing waterborne polyurethane according to any one of claims 1 to 7 in metal coatings, wood coatings, textile coatings, furniture coatings, and packaging coatings.

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