CN113058510B - Hybrid self-repairing microcapsule and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of self-repairing microcapsule particles, in particular to a hybrid self-repairing microcapsule and a preparation method thereof. The method comprises the following steps: 1) adding urea, ammonium chloride and resorcinol to the emulsifier aqueous solution to obtain a mixed solution; 2) adding a self-healing agent and a polyurethane prepolymer to the mixed solution to obtain an oil-in-water emulsion; 3 ) adding a formaldehyde solution to the oil-in-water emulsion, and heating up the reaction; adding an imidazole-2-formaldehyde solution, and continuing the reaction to obtain a self-repairing microcapsule whose surface is modified by an imidazole group; 4) redispersing the self-repairing microcapsule in the imidazole Aqueous solution of zinc salt, organic amine, and water-soluble corrosion inhibitor are added to the aqueous solution of the organic ligand, and stirred to obtain hybrid self-healing microcapsules. The repairing agent covered by the self-healing microcapsules in the present invention is a reactive repairing agent. When the microcapsules are broken, the repairing agent flows out and fills the microcracks to realize the self-repairing of the coating.

Description

A kind of hybrid self-healing microcapsule and preparation method thereof

technical field

The invention relates to the technical field of self-repairing microcapsule particles, in particular to a hybrid self-repairing microcapsule and a preparation method thereof.

Background technique

Inspired by nature, the self-healing microcapsule technology forms a biomimetic self-healing system inside the material by pre-compositing microcapsules in the traditional matrix material to perform "targeted" repair of cracks. The technical method is simple and does not require secondary maintenance, which can greatly reduce engineering maintenance costs, and is of great significance for eliminating material damage caused by micro-cracks and extending service life. Self-healing microcapsule technology provides a better solution for the corrosion of metal substrates caused by coating microcracks. For example, the patent application 201711424463.0 discloses an anti-corrosion primer containing self-healing microcapsules. When the microcapsules are damaged, the repair solution encapsulated therein automatically flows out, thereby realizing the self-repairing of the primer. In order to improve the stability and self-healing anticorrosion ability of microcapsules, microcapsules with multi-layer or special wall structure have been used in anticorrosion coatings in recent years. For example, patent application CN201710501268 discloses a microcapsule with double-layer capsule walls and a corrosion inhibitor is loaded between the capsule walls. In patent application CN201910353608.5, conductive polyaniline is used as the microcapsule wall material, which further improves the anticorrosion ability of the microcapsules. Patent application CN201910856507.X discloses self-healing microcapsules with calcium carbonate/polyaniline double-layer capsule wall structure.

The above microcapsules can only release the repairing agent after responding to mechanical rupture, and have no environmental responsiveness. Patent application CN111234566A discloses an acid-base pH-responsive composite silica nano-container, which improves the compatibility with the coating and enhances the self-healing and anti-corrosion capability of the coating. However, there is currently no microcapsule with pH responsiveness, strong wall structure stability and mechanical strength, and the ability to release repairing agents to fill microcracks and achieve self-healing.

SUMMARY OF THE INVENTION

Based on the above deficiencies, the present invention provides a hybrid self-healing microcapsule and a preparation method thereof. The hybrid microcapsule comprises an active reactive self-healing core material, a polyurethane wrapping the core material, a polyurea formaldehyde polymer wall material layer and The outermost metal organic frame wall material layer. The microcapsule of the invention has a multi-layer hybrid capsule wall structure, and the capsule wall structure is more stable, and can respond to environmental changes and crack expansion and damage, and exert a repairing effect.

To achieve the above object, the present invention has adopted the following technical scheme:

The invention provides a hybrid self-healing microcapsule, the hybrid self-repairing microcapsule comprises a core material and a wall material, the core material is a self-healing agent, and the wall material is a three-layer composite hybrid wall material. The outer order is polyurethane, polyurea formaldehyde, metal organic framework (MOF). The hybrid self-healing microcapsules have a particle size range of 5 microns to 500 microns, and the MOF particles have a particle size range of 0.01 microns to 1 micron.

When the microenvironment around the hybrid microcapsule is acidic, the MOF on the surface of the microcapsule is decomposed, and the released imidazole compounds can play a role in corrosion inhibition. When the microcapsule is further damaged, the reactive repairing agent in it is released, filling the microcapsule cracks, further preventing corrosion from occurring. In addition, the MOF on the surface of the microcapsules can also improve the structural stability of the microcapsule walls.

The present invention also provides a preparation method of hybrid self-healing microcapsules, comprising the following steps, in parts by mass:

1) adding 2.5-50 parts of urea, 0.25-5 parts of ammonium chloride, and 0.25-5 parts of resorcinol to 50-200 parts of an emulsifier aqueous solution with a mass fraction of 1-10 wt% to obtain a mixed solution for adjusting the mixed solution pH to 2.0～4.0;

2) adding 10-30 parts of self-healing agent and 2-10 parts of polyurethane prepolymer to the mixed solution obtained in step 1), and emulsifying at a stirring speed of 500-1200 rpm for 10-30 min to obtain an oil-in-water emulsion;

3) Add 3-10 parts of formaldehyde solution to the oil-in-water emulsion obtained in step 2), heat the temperature to 45-65° C. for 1-3 hours; add 0-5 parts of imidazole-2-formaldehyde aqueous solution with pH of 2.0-4.5 , continue the reaction for 1 to 3 hours; more preferably, add 1.5 to 5 parts of imidazole-2-carbaldehyde; after the reaction is completed, centrifuge at 1000 to 2000 rpm, wash, and repeat 3 to 5 times to obtain a self-modified surface with imidazole groups. Repair microcapsules;

4) Redispersing the self-healing microcapsules obtained in step 3) in an aqueous solution of imidazole organic ligands, adding an aqueous solution of zinc salts, organic amines, and water-soluble corrosion inhibitors, stirring for 0.5 to 2 hours, and after the reaction is completed, 1000 Centrifuge at ~2000 r/min, wash, repeat 3 to 5 times, and vacuum dry to obtain hybrid self-healing microcapsules.

Preferably, in the step 1), the emulsifier includes gum arabic, polyvinyl alcohol, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, ethylene-maleic anhydride copolymer and styrene-maleic anhydride One or more of the copolymers.

Preferably, in the step 2), the self-healing agent is selected from reactive self-healing agents, and the reactive self-healing agent includes one or more of isocyanate, epoxy resin and siloxane;

The polyurethane prepolymer includes toluene diisocyanate prepolymer, hexamethylene diisocyanate prepolymer, diphenylmethane diisocyanate prepolymer, dicyclohexylmethane diisocyanate prepolymer and isophorone diisocyanate One or more of prepolymers.

As preferably, in described step 4), organic amine is triethylamine and/or ammoniacal liquor;

The mass ratio of imidazole group-modified self-healing microcapsules to zinc salt is 1:1～10, and the molar ratio of zinc salt, imidazole organic ligand, organic amine, water-soluble corrosion inhibitor and water is 1:2～100:0 ～32:0～5:120～2255; more preferably, the molar ratio of zinc salt, imidazole type organic ligand, organic amine, water-soluble corrosion inhibitor and water is 1:2～100:10～32:2～5 : 120～2255;

Wherein, the imidazole organic ligands include 2-methylimidazole and/or imidazole-2-carbaldehyde;

Zinc salts include one or more of zinc nitrate hexahydrate, zinc chloride, zinc sulfate, zinc acetate and zinc gluconate;

Water-soluble corrosion inhibitors include one or more of benzotriazole, 2-mercaptobenzothiazole and water-based imidazoline corrosion inhibitors.

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

1. In the present invention, the hybrid self-healing microcapsules have a polyurethane/polyurea organic capsule wall layer and a MOF capsule wall layer. The nanoparticle hard layer endows the microcapsules with stronger structural stability, mechanical strength and structural compactness;

2. The MOF capsule wall layer in the present invention has pH responsiveness. Under the acidic corrosion microenvironment, the MOF decomposes and releases imidazole organic ligands, loaded water-soluble corrosion inhibitors and metal ions, which play a role in corrosion inhibition and prevent Further spread of corrosion at the damage;

3. The repairing agent covered by the self-healing microcapsules in the present invention is a reactive repairing agent. When the microcapsules are ruptured, the repairing agent in it flows out and fills the microcracks, and a new polymer is formed with the occurrence of the polymerization reaction. Self-healing of the coating;

4. The solvent used in the preparation of the hybrid microcapsules in the present invention is all water, no organic solvent is involved, and is more environmentally friendly.

Description of drawings

1 is a scanning electron microscope image of the hybrid self-healing microcapsule prepared in Example 1 of the present invention;

2 is a scanning electron microscope image of the surface of the hybrid self-healing microcapsule prepared in Example 1 of the present invention;

Fig. 3 is the XRD pattern of the hybrid self-healing microcapsule prepared in Example 1 of the present invention;

4 is a self-healing effect diagram of the hybrid self-healing microcapsule prepared in Example 1 of the present invention.

Detailed ways

The present invention will be described in further detail below with specific embodiments.

Example 1

Add 2.5g urea, 0.25g ammonium chloride, 0.25g resorcinol to 90g gum arabic aqueous solution with a mass fraction of 10wt%, adjust the pH of the mixture to 3.5; add 18g self-healing agent isophor to the above mixture The mixed solution of ketone diisocyanate and 4g of toluene diisocyanate prepolymer was emulsified for 30min at a stirring speed of 1100 rpm to obtain an oil-in-water emulsion; 4g of formaldehyde solution was added to the above-mentioned oil-in-water emulsion, and the temperature was raised to 55°C for reaction 1 h; add 1.3 g of an aqueous imidazole-2-formaldehyde solution with pH=3.5 to the above reaction solution, and continue the reaction for 2 h; after the reaction is completed, centrifuge, wash, and repeat 3 times to obtain self-repairing microcapsules whose surface is modified by imidazole groups; The microcapsules obtained above are redispersed in the 2-methylimidazole aqueous solution, and after uniform dispersion, added to the hexahydrate zinc nitrate aqueous solution. Among them, the mass ratio of self-healing microcapsules to zinc nitrate hexahydrate is 1:2, and the molar ratio of zinc nitrate hexahydrate: 2-methylimidazole: benzotriazole: deionized water is 1:100:5:2228 , stir for 0.5h, after the reaction is over, centrifuge, wash, repeat 3 times, and vacuum dry to obtain hybrid self-repairing microcapsules, as shown in Figure 1-4.

Example 2

Add 2.5g urea, 0.25g ammonium chloride, 0.25g resorcinol to 50g of styrene-maleic anhydride copolymer aqueous solution with a mass fraction of 5wt% to adjust the pH of the mixture to 4; add 4.5g to the above mixture The mixed solution of g self-healing agent epoxy resin and 4 g of toluene diisocyanate prepolymer was emulsified for 10 min at a stirring speed of 900 rpm to obtain an oil-in-water emulsion; 4 g of formaldehyde solution was added to the above-mentioned oil-in-water emulsion, and the temperature was raised to The reaction was carried out at 55°C for 3 hours; 0.6 g of imidazole-2-formaldehyde aqueous solution with pH=4 was added to the above reaction solution, and the reaction was continued for 2 hours; after the reaction was completed, centrifuge, washed, and repeated 3 times to obtain a self-healing surface modified with imidazole groups Microcapsules; the microcapsules obtained above are re-dispersed in the 2-methylimidazole aqueous solution, and after the dispersion is uniform, the hexahydrate zinc nitrate aqueous solution is added. Among them, the mass ratio of self-healing microcapsules to zinc nitrate hexahydrate is 1:10, and the molar ratio of zinc nitrate hexahydrate: 2-methylimidazole: ammonia water: benzotriazole: deionized water is 1:2:16 : 2:157, stir for 0.5h, after the reaction is over, centrifuge, wash, repeat 3 times, and vacuum dry to obtain hybrid self-repairing microcapsules.

Example 3

Add 50g urea, 5g ammonium chloride, 5g resorcinol to 200g of sodium lauryl sulfate aqueous solution whose mass fraction is 5wt%, adjust the pH of the mixed solution to 3; add 30g of self-healing agent silicon oxide to the above mixed solution The mixed solution of alkane and 10g of diphenylmethane diisocyanate prepolymer was emulsified for 30min at a stirring speed of 700 rev/min to obtain an oil-in-water emulsion; 10g of formaldehyde solution was added to the above-mentioned oil-in-water emulsion, and the temperature was raised to 55°C to carry out The reaction was performed for 3 hours; 4 g of imidazole-2-formaldehyde aqueous solution was added to the above reaction solution, and the reaction was continued for 3 hours; after the reaction was completed, centrifugation, washing, and repeated 3 times were performed to obtain self-repairing microcapsules modified by imidazole groups on the surface; The capsules were re-dispersed in the imidazole-2-formaldehyde aqueous solution, and after the dispersion was uniform, the zinc acetate aqueous solution was added. Among them, the mass ratio of self-healing microcapsules to zinc nitrate hexahydrate is 1:5, and the molar ratio of zinc acetate: imidazole-2-formaldehyde: aqueous imidazoline corrosion inhibitor: deionized water is 1:4:0.8:120 , stir for 0.5h, after the reaction is over, centrifuge, wash, repeat 3 times, and vacuum dry to obtain hybrid self-healing microcapsules.

Example 4

Add 2.5g urea, 0.25g ammonium chloride, 0.25g resorcinol to 100g polyvinyl alcohol aqueous solution with a mass fraction of 3wt%, adjust the pH of the mixed solution to 2.5; add 10g self-healing agent isophor to the above mixed solution The mixed solution of Erone diisocyanate and 2g hexamethylene diisocyanate prepolymer was emulsified for 30min at a stirring speed of 500 rev/min to obtain an oil-in-water emulsion; 3g of formaldehyde solution was added to the above-mentioned oil-in-water emulsion, and the temperature was raised to The reaction was carried out at 55 °C for 3 hours; 1.5 g of imidazole-2-formaldehyde aqueous solution with pH=4 was added to the above reaction solution, and the reaction was continued for 2 hours; after the reaction was completed, centrifuge, washed, and repeated 3 times to obtain a surface with imidazole groups modified and self-repairing Microcapsules; redisperse the microcapsules obtained above in the 2-methylimidazole aqueous solution, and after uniform dispersion, add the hexahydrate zinc nitrate aqueous solution. Among them, the mass ratio of microcapsules to zinc nitrate hexahydrate is 1:5, the molar ratio of zinc nitrate hexahydrate: 2-methylimidazole: triethylamine: deionized water is 1: 16: 16: 2255, and stirring is 0.5h , after the reaction is completed, centrifuge, wash, repeat 3 times, and vacuum dry to obtain hybrid self-repairing microcapsules.

Example 5

Add 2.5g of urea, 0.25g of ammonium chloride, 0.25g of resorcinol to 100g of sodium lauryl sulfate aqueous solution with a mass fraction of 1wt%, and adjust the pH of the mixed solution to 2.5; add 10g of self-healing to the above-mentioned mixed solution A mixed solution of dicyclohexylmethane diisocyanate and 2g of hexamethylene diisocyanate prepolymer was emulsified for 30min at a stirring speed of 500 rpm to obtain an oil-in-water emulsion; 3g of formaldehyde solution was added to the above emulsion, and the temperature was raised to The reaction was carried out at 55°C for 3 hours; 1.5 g of imidazole-2-formaldehyde aqueous solution with pH=4 was added to the above reaction solution, and the reaction was continued for 2 hours; after the reaction was completed, centrifuge, washed, and repeated 3 times to obtain a self-healing surface modified with imidazole groups Microcapsules; the microcapsules obtained above are redispersed in an aqueous imidazole-2-formaldehyde solution, and after uniform dispersion, an aqueous solution of zinc nitrate hexahydrate is added. Among them, the mass ratio of self-healing microcapsules to zinc nitrate hexahydrate is 1:5, the molar ratio of zinc nitrate hexahydrate: imidazole-2-carbaldehyde: triethylamine: deionized water is 1: 16: 16: 2255, stirring 0.5h, after the reaction is over, centrifugation, washing, repeating 3 times, and vacuum drying to obtain hybrid self-repairing microcapsules.

Example 6

Add 1.5g urea, 0.15g ammonium chloride, 0.15g resorcinol to 80g gum arabic aqueous solution with a mass fraction of 5wt%, adjust the pH of the mixture to 3.5; add 5g self-healing agent hexamethylene to the above mixture The mixed solution of diisocyanate and 1 g of isophorone diisocyanate prepolymer was emulsified at a stirring rate of 1000 rpm for 20 min to obtain an oil-in-water emulsion; 3 g of formaldehyde solution was added to the above emulsion, and the temperature was raised to 55 ° C for reaction 4h; after the reaction is completed, centrifuge, wash, and repeat 3 times to obtain self-repairing microcapsules modified by imidazole groups on the surface; redisperse the microcapsules obtained above in 2-methylimidazole aqueous solution, and after uniform dispersion, add zinc sulfate aqueous solution. Among them, the mass ratio of self-healing microcapsules to zinc sulfate is 1:1, the molar ratio of zinc sulfate:2-methylimidazole:deionized water is 1:70:1238, stirring for 0.5h, after the reaction is over, centrifugation, Washing, repeated 3 times, and vacuum drying to obtain hybrid self-healing microcapsules.

For the content not described in detail in the present invention, conventional technical knowledge in the field can be used.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention will not depart from the spirit and scope of the technical solutions of the present invention, and should be included in the present invention. within the scope of the claims.

Claims (6)

1. A preparation method of a hybrid self-repairing microcapsule comprises the following steps of:

1) adding 2.5-50 parts of urea, 0.25-5 parts of ammonium chloride and 0.25-5 parts of resorcinol into 50-200 parts of emulsifier aqueous solution with the mass fraction of 1-10 wt% to obtain a mixed solution, and adjusting the pH of the mixed solution to 2.5-4.0;

2) adding 10-30 parts of self-repairing agent and 2-10 parts of polyurethane prepolymer into the mixed solution obtained in the step 1), and then stirring and emulsifying for 10-30 minutes to obtain an oil-in-water emulsion;

3) adding 3-10 parts of formaldehyde solution into the oil-in-water emulsion obtained in the step 2), and heating to 45-65 ℃ to react for 1-4 h; adding 0.6-5 parts of imidazole-2-formaldehyde aqueous solution with the pH value of 2.0-4.5, continuously reacting for 1-3 hours, centrifuging after the reaction is finished, and washing to obtain a self-repairing microcapsule with the surface modified by imidazole groups, wherein the self-repairing agent comprises one or more than two of isocyanate, epoxy resin and siloxane;

the polyurethane prepolymer comprises one or more than two of toluene diisocyanate prepolymer, hexamethylene diisocyanate prepolymer, diphenylmethane diisocyanate prepolymer, dicyclohexylmethane diisocyanate prepolymer and isophorone diisocyanate prepolymer;

4) re-dispersing the self-repairing microcapsule obtained in the step 3) in an aqueous solution of an imidazole organic ligand, adding an aqueous solution of zinc salt, organic amine and a water-soluble corrosion inhibitor, stirring for 0.5-2 h, centrifuging after the reaction is finished, washing, and drying to obtain a hybrid self-repairing microcapsule, wherein the mass ratio of the imidazole group modified self-repairing microcapsule to the zinc salt is 1: 1-10, wherein the molar ratio of zinc salt, imidazole organic ligand, organic amine, water-soluble corrosion inhibitor and water is 1: 2-100: 10-32: 2-5: 120 to 2255; wherein the water-soluble corrosion inhibitor comprises one or more than two of benzotriazole, 2-mercaptobenzothiazole and waterborne imidazoline corrosion inhibitors;

the hybrid self-repairing microcapsule comprises a core material and a wall material, wherein the core material is a self-repairing agent, the wall material is a three-layer composite hybrid wall material, and the three-layer composite hybrid wall material sequentially comprises polyurethane, polyureaformaldehyde and a metal organic framework from inside to outside.

2. The method for preparing hybrid self-repairing microcapsules according to claim 1, wherein in the step 1), the emulsifier comprises one or more of gum arabic, polyvinyl alcohol, sodium dodecylbenzene sulfonate, sodium dodecylsulfate, ethylene-maleic anhydride copolymer and styrene-maleic anhydride.

3. The preparation method of hybrid self-repairing microcapsules according to claim 1, wherein the organic amine in the step 4) is triethylamine.

4. The preparation method of hybrid self-repairing microcapsules according to claim 1, wherein the imidazole organic ligand in step 4) is 2-methylimidazole and/or imidazole-2-formaldehyde.

5. The preparation method of hybrid self-repairing microcapsules according to claim 1, wherein the zinc salt in step 4) is one or more of zinc nitrate hexahydrate, zinc chloride, zinc sulfate, zinc acetate and zinc gluconate.

6. A hybrid self-repairing microcapsule, which is prepared by the preparation method of any one of claims 1 to 5.

Images