A hydrophobic double-shell isocyanate type self-repairing microcapsule and its preparation method and application
By adopting the isocyanate-type self-repair microcapsules with a hydrophobic double-shell structure, the problems of poor fluidity and poor shell density in the prior art are solved, and efficient self-repair and multifunctional coating performance are achieved.
Patent Information
- Application Number
- CN202210662546.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-13
- Publication Date
- 2025-03-11
- Estimated Expiration
- 2042-06-13
AI Technical Summary
The repair agents of existing self-repair microcapsules have high viscosity and poor fluidity, which require external conditions to be involved in repair, resulting in high cost and low efficiency, poor shell density, low mechanical strength, short storage time and poor environmental tolerance.
The isocyanate-type self-healing microcapsules with hydrophobic bihull structure were prepared by TMP and IPDI monomers, and the polyurethane was used as the wall material, and fluorescent isocyanate-type microcapsules were prepared by interfacial polymerization and sol-gel method, and then the hydrophobic bihull structure was formed by modified silica coating.
It improves self-healing efficiency and density, extends the storage time of microcapsules, enhances the hydrophobic and anti-corrosion properties of the coating, and realizes the self-healing and self-detection function.
Smart Images
Figure CN114950293B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of polymer chemistry, and in particular relates to a hydrophobic double-shell isocyanate type self-repairing microcapsule and a preparation method and application thereof. Background Art
[0002] During the use of coating materials, the micro-nano rough structure on their surface is easily scratched and damaged by external forces, thus affecting the performance of the material, which to a large extent limits its large-scale promotion and practical application.
[0003] In order to overcome the above problems, some researchers added self-healing microcapsules to coating materials to prepare self-healing coating materials with excellent surface stability and recyclability. When its surface is damaged, the microcapsules rupture, and the capsule core flows out to repair microcracks. The coating performance can be improved spontaneously or under certain conditions. At present, the repair agent (capsule core) contained in traditional self-healing microcapsules has high viscosity and poor fluidity. Its repair requires the participation of curing agents and external light, electricity and other conditions to play a repair role, which limits its practical application and has high cost. In response to the above problems, the laboratory prepared isocyanate microcapsules. The principle is that when the shell material is broken, the isocyanate capsule core reacts with water and oxygen in the air to achieve self-repair. It has the advantages of low viscosity of the repair agent (capsule core), strong fluidity, low cost and low pollution.
[0004] However, the pure isocyanate (capsule core) monomer has low reactivity. As the core material of microcapsule self-healing coating, it has problems such as corrosion resistance and low self-healing efficiency. The traditional microcapsule shell prepared by interfacial polymerization has poor density and low mechanical strength. It cannot effectively protect the isocyanate capsule core that can react in the air for a long time, resulting in the microcapsule having problems such as short storage time and poor environmental tolerance. Summary of the invention
[0005] In order to solve the defects existing in the above-mentioned prior art, the present invention discloses a hydrophobic double-shell isocyanate type self-healing microcapsule and a preparation method and application thereof. The operation is simple, and the prepared microcapsule has high self-healing efficiency and good density.
[0006] The present invention is achieved through the following technical solutions:
[0007] The present invention discloses a method for preparing a hydrophobic double-shell isocyanate type self-repairing microcapsule, comprising the following steps:
[0008] S1: Preparation of multifunctional isocyanate prepolymer core material TMP-IPDI using TMP and IPDI monomers;
[0009] S2: Using polyurethane as the wall material, the core material prepared in S1 and the fluorescent agent 4,4-bis(2-sodium disulfonate styryl)biphenyl were used to prepare fluorescent isocyanate type self-healing microcapsule powder;
[0010] S3: The fluorescent isocyanate self-healing microcapsules prepared in S2 were secondary coated with tridecafluorooctyltrimethoxysilane-modified silica to obtain hydrophobic double-shell isocyanate self-healing microcapsules.
[0011] Preferably, S1 is specifically as follows: in parts by mass, 2 parts of TMP, 10 parts of cyclohexanone and 6 parts of benzene are mixed and stirred, and placed in a heating bath and heated to 75°C, and then cooled to 60°C to obtain a dry solution for standby use; 13 parts of IPDI are placed in a heating bath at 40°C, 0.08 parts of DBTDL are added under stirring, and the dry solution is added dropwise, and after the addition is completed, the reaction temperature is increased to 60°C, and the reaction is continued for 5 hours to obtain a multifunctional isocyanate prepolymer core material TMP-IPDI.
[0012] More preferably, the dripping time of the drying solution does not exceed 1 hour.
[0013] Preferably, S2 is specifically as follows: 5 parts of ethyl acetate, 0.8-4.1 parts of HDI trimer, 5 parts of TMP-IPDI prepared in S1 and 0.1-0.5 parts of 4,4-bis(2-sodium disulphonate styryl)biphenyl are weighed by mass, and stirred evenly at room temperature to form an oil phase system; gum arabic is put into 120 parts of distilled water, and stirred evenly at room temperature to form an aqueous phase system; the prepared aqueous phase system is stirred at high speed, and the oil phase system is slowly poured into the aqueous phase system, and the mixture is emulsified for 15 minutes to obtain a suspension system; 0.2-1.0 parts of BDO are added to the suspension system, and the reaction is continued for 2-6 hours at a temperature of 40-80°C and a rotation speed of 300-700rpm. After the reaction is completed, the obtained microcapsule suspension is naturally cooled, and suction filtration, water washing and drying are repeatedly performed to obtain a fluorescent isocyanate type self-healing microcapsule powder.
[0014] More preferably, the rotation speed of the aqueous phase system during high-speed stirring is 8000 rpm.
[0015] Preferably, S3 is specifically as follows: 2 parts by mass of fluorescent isocyanate self-healing microcapsule powder prepared by S2 are taken, dispersed in 10 parts of deionized water, 2-10 parts of tetraethyl orthosilicate alcohol solution prepared by TEOS and ethanol are added, and stirred at 50°C at a speed of 500r / min for 30min, and then the pH is adjusted to 9 to induce the hydrolysis reaction of TEOS; after continuous stirring for 30min, tridecafluorooctyltrimethoxysilane is added and reacted for 5h; the temperature is raised to 85°C and stirring is continued, and condensation and reflux are carried out until the ethanol is completely evaporated; the temperature is lowered to 40°C, aged for 12h, and stirring is maintained; after the reaction is completed, the product is washed and filtered, and placed in an oven at 40°C for 2h to obtain hydrophobic double-shell isocyanate self-healing microcapsules.
[0016] More preferably, the pH is adjusted by dripping ammonia or hydrochloric acid; and petroleum ether and deionized water are used for washing.
[0017] The invention discloses a hydrophobic double-shell isocyanate type self-repairing microcapsule prepared by the preparation method, which has a spherical appearance, a flat and smooth surface, a particle size of 10-70um, and a wall thickness of 0.67-4.69um.
[0018] The invention discloses application of the hydrophobic double-shell isocyanate type self-repairing microcapsule as a self-repairing filler in a coating.
[0019] Preferably, the mass fraction of the hydrophobic double-shell isocyanate type self-healing microcapsules in the coating is 3%-5%.
[0020] Compared with the prior art, the present invention has the following beneficial technical effects:
[0021] The preparation method of the hydrophobic double-shell isocyanate self-repairing microcapsules disclosed in the present invention adopts an interfacial polymerization method to prepare fluorescent isocyanate self-repairing microcapsules with environmentally friendly polyurethane as wall material, multifunctional high molecular weight TMP-IPDI and 4,4-bis(2-sodium disulfonate styrene) biphenyl as core material. By using a sol-gel method, silicon dioxide prepared by hydrolysis of ethyl orthosilicate is adsorbed on the surface of the microcapsule to form a silicon dioxide double shell, and silicon dioxide is modified with tridecafluorooctyl trimethoxysilane to prepare a double-shell isocyanate self-repairing microcapsule with hydrophobic, anticorrosive and fluorescent detection performance, and the fluorescent double-shell microcapsules are applied to polyurethane coatings. When microcracks appear in the coating due to external force, the microcapsules at the microcracks are broken, and the multifunctional isocyanate and fluorescent agent 4,4-bis(2-sodium disulfonate styrene) biphenyl wrapped in the microcapsules flow out, and the isocyanate group reacts with water in the air to form polyurea to fill the microcracks, thereby achieving the effect of repairing the microcracks. At the same time, the repaired part produces green fluorescence after irradiation with ultraviolet light to achieve the self-repair and self-detection functions; the fluorine element on the surface of the modified silica double-shell microcapsule will migrate to the coating surface, making the coating surface hydrophobic, and the hydrophobic function can be restored at the repaired part. Through the above treatment, the present invention not only successfully prepared fluorescent double-shell isocyanate self-repairing microcapsules, but also successfully applied them to polyurethane coatings, so that the polyurethane coating has excellent self-repairing properties. The multi-functional high-molecular weight TMP-IPDI core material has high reaction activity, which improves the self-repair efficiency of the coating. Silica is modified with tridecafluorooctyltrimethoxysilane, so that the coating has self-repair and self-detection functions while enhancing the hydrophobicity, anti-corrosion and other properties of the coating.
[0022] Furthermore, the purpose of selecting benzene during the core material preparation process is to remove water from TMP and prevent water from reacting with IPDI to form polyurea.
[0023] Furthermore, the drying solution is added dropwise for a long time during the core material preparation process in order to allow TMP and IPDI to react evenly and fully and to prevent agglomeration from occurring, which may lead to incomplete reaction.
[0024] Furthermore, the selection of 4,4-bis(2-sodium disulphonate styryl)biphenyl in the core material of the fluorescent double-shell isocyanate microcapsule is for the purpose of low cost and strong fluorescence of the fluorescent agent. The fluorescent agent only needs to be added to 2% of the total amount of the microcapsule to make the microcapsule have strong fluorescence properties.
[0025] Furthermore, the selection of the rotation speed during the emulsification process aims to disperse the oil phase evenly in the water phase to form an emulsion with uniform size and small particle size.
[0026] Furthermore, the amount of ethyl orthosilicate is selected during the double-shell coating process to minimize the double-shell particle size and make the coating most dense, thereby forming double-shell self-healing microcapsules with small particle size and good density.
[0027] Furthermore, the selection of pH during the double-shell coating process is mainly to make the double-shell coating most dense, thereby enhancing the density of the isocyanate-type self-healing microcapsules and improving their self-healing efficiency.
[0028] The hydrophobic double-shell isocyanate type self-repairing microcapsules disclosed in the present invention are prepared by the above method. The core material of the microcapsules is a multifunctional isocyanate with high reactivity. The surface of the microcapsules has a dense silicon dioxide layer, which can improve the sealing of the isocyanate type microcapsules and make the storage time of the microcapsules longer. The fluorine-modified silicon dioxide gives the microcapsule surface hydrophobicity and other functions.
[0029] The application of the hydrophobic double-shell isocyanate self-healing microcapsules disclosed in the present invention as self-healing fillers in coatings can repair microcracks in coatings. The modified double-shell microcapsules enable the coatings to achieve self-healing and self-detection functions while having hydrophobic, anti-corrosion and other functions. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 Infrared image of the double-shell microcapsule core material prepared by the present invention;
[0031] Figure 2 The infrared images of the single-shell and double-shell microcapsules prepared by the present invention are shown below;
[0032] Figure 3 The particle size and scanning diagram of the double-shell microcapsule prepared by the present invention;
[0033] Figure 4 This is a scanned image of a double-shell microcapsule prepared by the present invention;
[0034] Figure 5 This is a scanned image of the double-shell microcapsule wall material prepared by the present invention;
[0035] Figure 6 The contact angles of the coatings prepared with different addition amounts of double-shell microcapsules of the present invention;
[0036] Figure 7 This is a scan of the polyurethane coating containing 3% microcapsules before self-repair;
[0037] Figure 8 This is a scan of a polyurethane coating with 3% microcapsule addition after self-repair. DETAILED DESCRIPTION
[0038] In this article, TMP is trimethylolpropane, IPDI is isophorone diisocyanate, DBTDL is di-n-butyltin dilaurate, HDI is hexamethylene diisocyanate, BDO is 1,4-butanediol, and TEOS is tetraethoxysilane.
[0039] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.
[0040] Example 1
[0041] Step 1: Preparation of multifunctional isocyanate prepolymer core material
[0042] 2 g of TMP, 10 g of cyclohexanone and 6 g of benzene were added together and stirred in a 100 ml three-necked round-bottom flask equipped with a condenser and a magnetic stirrer, and placed in a heating bath and heated to 75°C; the benzene removed the moisture in the solution, and then the solution was cooled to 60°C to obtain a dry solution. The solution was added to a dropping funnel. 13 g of IPDI was added to a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer and placed in a heating bath. The temperature was controlled at 40°C, and 0.08 g of DBTDL was added under magnetic stirring. The solution in the dropping funnel was transferred to the flask within 1 hour. Then, the reaction temperature was raised to about 60°C and the reaction was continued for 5 hours.
[0043] Step 2: Preparation of fluorescent isocyanate self-healing microcapsules
[0044] Prepare the oil phase: weigh 5 g of TMP-IPDI, 1% of 4,4-bis(2-sodium disulphonate styryl)biphenyl and 4.1 g of HDI trimer, and 5 g of ethyl acetate, and stir evenly at room temperature to prepare the oil phase system.
[0045] Prepare the aqueous phase: Weigh a certain amount of gum arabic, add it into 120 mL of distilled water, and stir evenly at room temperature to prepare the aqueous phase system.
[0046] Emulsified suspension: place the water phase system in a digital disperser at a speed of 8000 rpm, then slowly pour the oil phase system into the water phase system, mix the two and continue emulsification for 15 minutes to obtain a suspension system.
[0047] Preparation of microcapsules: The suspension system obtained by emulsification was poured into a three-necked flask, which was placed in a constant temperature water bath. Then, 1 g of BDO (dissolved in 5 mL of water) was added. After the addition was completed, the system was allowed to react for 2 h at 40 ° C and 300 rpm. After the reaction was completed, the obtained microcapsule suspension was naturally cooled, and suction filtration, water washing and drying were repeated to obtain a white powder of microcapsules.
[0048] Step 3: Preparation of modified silica double-shell isocyanate microcapsules
[0049] Take 2g of the prepared fluorescent isocyanate microcapsules, disperse them in 10g of deionized water, and transfer them to a three-necked flask. Prepare an alcohol solution of ethyl orthosilicate with 2g of TEOS and (1:1) ethanol and stir evenly. Pour the three-necked flask containing the fluorescent isocyanate microcapsules and stir at 50°C at a speed of 500r / min for 30min to make the microcapsules fully and evenly dispersed in the TEOS solution. Add ammonia (hydrochloric acid) to the flask to adjust the pH of the solution to 9. Initiate the hydrolysis reaction of TEOS. Continue stirring for 30min, add a certain amount of tridecafluorooctyl trimethoxysilane, and react for 5h. Raise the temperature to 85°C and continue stirring, condense and reflux until all the ethanol evaporates. Lower the temperature to 40°C and age for 12h without stopping stirring. After the reaction, wash the product with petroleum ether and deionized water, filter it with suction, and dry it in an oven at 40°C for 2h to obtain modified SiO2 / PU microcapsules.
[0050] Example 2
[0051] A method for preparing a hydrophobic double-shell isocyanate type self-repairing microcapsule comprises the following steps:
[0052] Example 2
[0053] Step 1: Preparation of multifunctional isocyanate prepolymer core material
[0054] 2 g of TMP, 10 g of cyclohexanone and 6 g of benzene were added together and stirred in a 100 ml three-necked round-bottom flask equipped with a condenser and a magnetic stirrer, and placed in a heating bath and heated to 75°C; the benzene removed the moisture in the solution, and then the solution was cooled to 60°C to obtain a dry solution. The solution was added to a dropping funnel. 13 g of IPDI was added to a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer and placed in a heating bath. The temperature was controlled at 40°C, and 0.08 g of DBTDL was added under magnetic stirring. The solution in the dropping funnel was transferred to the flask within 1 hour. Then, the reaction temperature was raised to about 60°C and the reaction was continued for 5 hours.
[0055] Step 2: Preparation of fluorescent isocyanate self-healing microcapsules
[0056] Prepare the oil phase: weigh 5 g of TMP-IPDI, 0.2 g of 4,4-bis(2-sodium disulphonate styryl)biphenyl and 2.1 g of HDI trimer, and 5 g of ethyl acetate, and stir evenly at room temperature to prepare the oil phase system.
[0057] Prepare the aqueous phase: Weigh a certain amount of gum arabic, add it into 120 mL of distilled water, and stir evenly at room temperature to prepare the aqueous phase system.
[0058] Emulsified suspension: place the water phase system in a digital disperser at a speed of 8000 rpm, then slowly pour the oil phase system into the water phase system, mix the two and continue emulsification for 15 minutes to obtain a suspension system.
[0059] Preparation of microcapsules: The suspension system obtained by emulsification was poured into a three-necked flask, which was placed in a constant temperature water bath, and then 0.4 g of BDO (dissolved in 5 mL of water) was added. After the addition was completed, the system was allowed to react for 3 hours at 50° C. and 400 rpm. After the reaction was completed, the obtained microcapsule suspension was naturally cooled, and suction filtration, water washing, and drying were repeated to obtain a white powder of microcapsules.
[0060] Step 3: Preparation of modified silica double-shell isocyanate microcapsules
[0061] Take 2g of the prepared fluorescent isocyanate microcapsules, disperse them in 10g of deionized water, and transfer them to a three-necked flask. Prepare an alcohol solution of tetraethyl orthosilicate with 4g of TEOS and (1:1) ethanol and stir evenly. Pour the three-necked flask containing the fluorescent isocyanate microcapsules and stir at 50°C at a speed of 500r / min for 30min to make the microcapsules fully and evenly dispersed in the TEOS solution. Add ammonia (hydrochloric acid) to the flask to adjust the pH of the solution to 9. Initiate the hydrolysis reaction of TEOS. Continue stirring for 30min, add a certain amount of tridecafluorooctyl trimethoxysilane, and react for 5h. Raise the temperature to 85°C and continue stirring, condense and reflux until all the ethanol evaporates. Lower the temperature to 40°C and age for 12h without stopping stirring. After the reaction, wash the product with petroleum ether and deionized water, filter it with suction, and dry it in an oven at 40°C for 2h to obtain modified SiO2 / PU microcapsules.
[0062] Example 3
[0063] A method for preparing a hydrophobic double-shell isocyanate type self-repairing microcapsule comprises the following steps:
[0064] Example 3
[0065] Step 1: Preparation of multifunctional isocyanate prepolymer core material
[0066] 2 g of TMP, 10 g of cyclohexanone and 6 g of benzene were added together and stirred in a 100 ml three-necked round-bottom flask equipped with a condenser and a magnetic stirrer, and placed in a heating bath and heated to 75°C; the benzene removed the moisture in the solution, and then the solution was cooled to 60°C to obtain a dry solution. The solution was added to a dropping funnel. 13 g of IPDI was added to a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer and placed in a heating bath. The temperature was controlled at 40°C, and 0.08 g of DBTDL was added under magnetic stirring. The solution in the dropping funnel was transferred to the flask within 1 hour. Then, the reaction temperature was raised to about 60°C and the reaction was continued for 5 hours.
[0067] Step 2: Preparation of fluorescent isocyanate self-healing microcapsules
[0068] Prepare the oil phase: weigh 5 g of TMP-IPDI, 0.3 g of 4,4-bis(2-sodium disulphonate styryl)biphenyl and 1.4 g of HDI trimer, and 5 g of ethyl acetate, and stir evenly at room temperature to prepare the oil phase system.
[0069] Prepare the aqueous phase: Weigh a certain amount of gum arabic, add it into 120 mL of distilled water, and stir evenly at room temperature to prepare the aqueous phase system.
[0070] Emulsified suspension: place the water phase system in a digital disperser at a speed of 8000 rpm, then slowly pour the oil phase system into the water phase system, mix the two and continue emulsification for 15 minutes to obtain a suspension system.
[0071] Preparation of microcapsules: The suspension system obtained by emulsification was poured into a three-necked flask, which was placed in a constant temperature water bath, and then 0.3 g of BDO (dissolved in 5 mL of water) was added. After the addition was completed, the system was allowed to react for 4 hours at 60° C. and 500 rpm. After the reaction was completed, the obtained microcapsule suspension was naturally cooled, and suction filtration, water washing, and drying were repeated to obtain a white powder of microcapsules.
[0072] Step 3: Preparation of modified silica double-shell isocyanate microcapsules
[0073] Take 2g of the prepared fluorescent isocyanate microcapsules, disperse them in 10g of deionized water, and transfer them to a three-necked flask. Prepare an alcohol solution of ethyl orthosilicate with 6g of TEOS and (1:1) ethanol and stir evenly. Pour the three-necked flask containing the fluorescent isocyanate microcapsules and stir at 50°C at a speed of 500r / min for 30min to make the microcapsules fully and evenly dispersed in the TEOS solution. Add ammonia (hydrochloric acid) to the flask to adjust the pH of the solution to 9. Initiate the hydrolysis reaction of TEOS. Continue stirring for 30min, add a certain amount of tridecafluorooctyl trimethoxysilane, and react for 5h. Raise the temperature to 85°C and continue stirring, condense and reflux until all the ethanol evaporates. Lower the temperature to 40°C and age for 12h without stopping stirring. After the reaction, wash the product with petroleum ether and deionized water, filter it with suction, and dry it in an oven at 40°C for 2h to obtain modified SiO2 / PU microcapsules.
[0074] Example 4
[0075] A method for preparing a hydrophobic double-shell isocyanate type self-repairing microcapsule comprises the following steps:
[0076] Example 4
[0077] Step 1: Preparation of multifunctional isocyanate prepolymer core material
[0078] 2 g of TMP, 10 g of cyclohexanone and 6 g of benzene were added together and stirred in a 100 ml three-necked round-bottom flask equipped with a condenser and a magnetic stirrer, and placed in a heating bath and heated to 75°C; the benzene removed the moisture in the solution, and then the solution was cooled to 60°C to obtain a dry solution. The solution was added to a dropping funnel. 13 g of IPDI was added to a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer and placed in a heating bath. The temperature was controlled at 40°C, and 0.08 g of DBTDL was added under magnetic stirring. The solution in the dropping funnel was transferred to the flask within 1 hour. Then, the reaction temperature was raised to about 60°C and the reaction was continued for 5 hours.
[0079] Step 2: Preparation of fluorescent isocyanate self-healing microcapsules
[0080] Prepare the oil phase: weigh 5 g of TMP-IPDI, 0.4 g of 4,4-bis(2-sodium disulphonate styryl)biphenyl and 1.0 g of HDI trimer, and 5 g of ethyl acetate, and stir evenly at room temperature to prepare the oil phase system.
[0081] Prepare the aqueous phase: Weigh a certain amount of gum arabic, add it into 120 mL of distilled water, and stir evenly at room temperature to prepare the aqueous phase system.
[0082] Emulsified suspension: place the water phase system in a digital disperser at a speed of 8000 rpm, then slowly pour the oil phase system into the water phase system, mix the two and continue emulsification for 15 minutes to obtain a suspension system.
[0083] Preparation of microcapsules: The suspension system obtained by emulsification was poured into a three-necked flask, which was placed in a constant temperature water bath, and then 0.2 g of BDO (dissolved in 5 mL of water) was added. After the addition was completed, the system was allowed to react for 5 h at 70° C. and 600 rpm. After the reaction was completed, the obtained microcapsule suspension was naturally cooled, and suction filtration, water washing, and drying were repeated to obtain a white powder of microcapsules.
[0084] Step 3: Preparation of modified silica double-shell isocyanate microcapsules
[0085] Take 2g of the prepared fluorescent isocyanate microcapsules, disperse them in 10g of deionized water, and transfer them to a three-necked flask. Prepare an alcohol solution of ethyl orthosilicate with 8g of TEOS and (1:1) ethanol and stir evenly. Pour the three-necked flask containing the fluorescent isocyanate microcapsules and stir at 50°C at a speed of 500r / min for 30min to make the microcapsules fully and evenly dispersed in the TEOS solution. Add ammonia (hydrochloric acid) to the flask to adjust the pH of the solution to 9. Initiate the hydrolysis reaction of TEOS. Continue stirring for 30min, add a certain amount of tridecafluorooctyl trimethoxysilane, and react for 5h. Raise the temperature to 85°C and continue stirring, condense and reflux until all the ethanol evaporates. Lower the temperature to 40°C and age for 12h without stopping stirring. After the reaction, wash the product with petroleum ether and deionized water, filter it with suction, and dry it in an oven at 40°C for 2h to obtain modified SiO2 / PU microcapsules.
[0086] Example 5
[0087] A method for preparing a hydrophobic double-shell isocyanate type self-repairing microcapsule comprises the following steps:
[0088] Example 5
[0089] Step 1: Preparation of multifunctional isocyanate prepolymer core material
[0090] 2 g of TMP, 10 g of cyclohexanone and 6 g of benzene were added together and stirred in a 100 ml three-necked round-bottom flask equipped with a condenser and a magnetic stirrer, and placed in a heating bath and heated to 75°C; the benzene removed the moisture in the solution, and then the solution was cooled to 60°C to obtain a dry solution. The solution was added to a dropping funnel. 13 g of IPDI was added to a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer and placed in a heating bath. The temperature was controlled at 40°C, and 0.08 g of DBTDL was added under magnetic stirring. The solution in the dropping funnel was transferred to the flask within 1 hour. Then, the reaction temperature was raised to about 60°C and the reaction was continued for 5 hours.
[0091] Step 2: Preparation of fluorescent isocyanate self-healing microcapsules
[0092] Prepare the oil phase: weigh 5 g of TMP-IPDI, 0.5 g of 4,4-bis(2-sodium disulphonate styryl)biphenyl and 0.8 g of HDI trimer, and 5 g of ethyl acetate, and stir evenly at room temperature to prepare the oil phase system.
[0093] Prepare the aqueous phase: Weigh a certain amount of gum arabic, add it into 120 mL of distilled water, and stir evenly at room temperature to prepare the aqueous phase system.
[0094] Emulsified suspension: place the water phase system in a digital disperser at a speed of 8000 rpm, then slowly pour the oil phase system into the water phase system, mix the two and continue emulsification for 15 minutes to obtain a suspension system.
[0095] Preparation of microcapsules: The suspension system obtained by emulsification was poured into a three-necked flask, which was placed in a constant temperature water bath, and then 0.2 g of BDO (dissolved in 5 mL of water) was added. After the addition was completed, the system was allowed to react for 6 hours at 80° C. and 700 rpm. After the reaction was completed, the obtained microcapsule suspension was naturally cooled, and suction filtration, water washing, and drying were repeated to obtain a white powder of microcapsules.
[0096] Step 3: Preparation of modified silica double-shell isocyanate microcapsules
[0097] Take 2g of the prepared fluorescent isocyanate microcapsules, disperse them in 10g of deionized water, and transfer them to a three-necked flask. Prepare an alcohol solution of tetraethyl orthosilicate with 10g of TEOS and (1:1) ethanol and stir evenly. Pour the three-necked flask containing the fluorescent isocyanate microcapsules into the three-necked flask and stir at 500r / min for 30min at 50℃ to make the microcapsules fully and evenly dispersed in the TEOS solution. Add ammonia (hydrochloric acid) to the flask to adjust the pH of the solution to 9. Initiate the hydrolysis reaction of TEOS. Continue stirring for 30min, add a certain amount of tridecafluorooctyl trimethoxysilane, and react for 5h. Raise the temperature to 85℃ and continue stirring, condense and reflux until all the ethanol evaporates. Lower the temperature to 40℃ and age for 12h without stopping stirring. After the reaction, wash the product with petroleum ether and deionized water, filter it with suction, and dry it in an oven at 40℃ for 2h to obtain modified SiO2 / PU microcapsules.
[0098] Figure 1 This is the infrared image of the microcapsule core material. Compared with IPDI, the core material TMP-IPDI has an infrared wavelength of 2273 cm -1 There is a stretching vibration peak of -NCO at 1472cm -1 There is a stretching vibration peak of -CH3 at 1365cm -1 There is a stretching vibration peak of -CH2 at , indicating that the core material TMP-IPDI was successfully synthesized.
[0099] Figure 2 The infrared images of polyurethane single-shell and silica double-shell microcapsules show that compared with single-shell microcapsules, silica double-shell microcapsules have a -1 The stretching vibration peak of Si-O-Si appeared at , indicating that the silica double shell was successfully coated.
[0100] Figure 3 The particle size and scanning image of the microcapsule show that the particle size of the double-shell microcapsule is 29.201um, and the particle size distribution is relatively uniform; the scanning image shows that the microcapsule is spherical with a flat and smooth surface.
[0101] Figure 4 This is a scanned image of the microcapsule. It can be seen from the image that the surface of the microcapsule is covered with a layer of silicon dioxide sheets, indicating that the double-shell microcapsule was successfully prepared.
[0102] Figure 5 To grind the damaged microcapsules, it can be seen from the figure that the wall thickness of the microcapsules is 2um.
[0103] Figure 6 The polyurethane coatings were prepared with different microcapsule addition amounts. It can be seen from the figure that when the microcapsule addition amount is 3%-5%, the coating has good hydrophobicity, and the hydrophobicity is optimal when the addition amount is 3%, and the contact angle can reach 104.4°.
[0104] Figure 7 and Figure 8 The scans of the polyurethane coating with 3% microcapsule addition before and after self-repair show that when the microcapsule addition amount is 3%, the coating has excellent self-repair effect.
[0105] The specific embodiments of the present invention are described in detail above, and the product phenomena of different embodiments are described, but they are only used as examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, the equalization changes and modifications made without departing from the spirit and scope of the present invention should be included in the scope of the present invention.
Claims
1. A method for preparing a hydrophobic double-shell isocyanate type self-healing microcapsule, characterized in that: The following steps are involved: S1: Preparation of multifunctional isocyanate prepolymer core material TMP-IPDI using TMP and IPDI monomers; S2: Using polyurethane as the wall material, the core material prepared in S1 and the fluorescent agent 4,4-bis(2-sodium disulfonate styryl)biphenyl were used to prepare fluorescent isocyanate type self-healing microcapsule powder; S2 is specifically as follows: 5 parts of ethyl acetate, 0.8-4.1 parts of HDI trimer, 5 parts of TMP-IPDI prepared in S1 and 0.1-0.5 parts of 4,4-bis(2-sodium disulphonate styryl)biphenyl are weighed by mass, and stirred evenly at room temperature to form an oil phase system; gum arabic is put into 120 parts of distilled water, and stirred evenly at room temperature to form an aqueous phase system; the prepared aqueous phase system is stirred at high speed, and the oil phase system is slowly poured into the aqueous phase system, and the mixture is emulsified for 15 minutes to obtain a suspension system; 0.2-1.0 parts of BDO are added to the suspension system, and the reaction is continued for 2-6 hours at a temperature of 40-80°C and a rotation speed of 300-700rpm. After the reaction is completed, the obtained microcapsule suspension is naturally cooled, and suction filtration, water washing and drying are repeated to obtain fluorescent isocyanate type self-healing microcapsule powder; S3: The fluorescent isocyanate self-healing microcapsules prepared in S2 are secondary coated with tridecafluorooctyltrimethoxysilane-modified silica to obtain hydrophobic double-shell isocyanate self-healing microcapsules.
2. The method for preparing the hydrophobic double-shell isocyanate type self-repairing microcapsule according to claim 1, characterized in that: S1 is specifically as follows: in parts by mass, 2 parts of TMP, 10 parts of cyclohexanone and 6 parts of benzene are mixed and stirred, and placed in a heating bath and heated to 75°C, and then cooled to 60°C to obtain a dry solution for standby use; 13 parts of IPDI are placed in a heating bath at 40°C, 0.08 parts of DBTDL are added under stirring, and the dry solution is added dropwise, and after the addition is completed, the reaction temperature is increased to 60°C, and the reaction is continued for 5 hours to obtain a multifunctional isocyanate prepolymer core material TMP-IPDI.
3. The method for preparing the hydrophobic double-shell isocyanate type self-repairing microcapsule according to claim 2, characterized in that: The addition time of the drying solution should not exceed 1h.
4. The method for preparing the hydrophobic double-shell isocyanate type self-repairing microcapsule according to claim 1, characterized in that: The rotation speed of the aqueous phase system during high-speed stirring is 8000 rpm.
5. The method for preparing the hydrophobic double-shell isocyanate type self-repairing microcapsule according to claim 1, characterized in that: S3 is specifically as follows: 2 parts by mass of the fluorescent isocyanate self-healing microcapsule powder prepared in S2 are dispersed in 10 parts of deionized water, 2-10 parts of an alcohol solution of ethyl orthosilicate prepared by TEOS and ethanol are added, the mixture is stirred at 50°C and 500 r / min for 30 min, and then the pH is adjusted to 9 to initiate a hydrolysis reaction of TEOS; After continuous stirring for 30 minutes, add tridecafluorooctyltrimethoxysilane and react for 5 hours; raise the temperature to 85°C and continue stirring, condense and reflux until the ethanol is completely evaporated; lower the temperature to 40°C, age for 12 hours, and keep stirring; after the reaction, wash and filter the product, and dry it in an oven at 40°C for 2 hours to obtain hydrophobic double-shell isocyanate type self-healing microcapsules.
6. The method for preparing the hydrophobic double-shell isocyanate type self-repairing microcapsule according to claim 5, characterized in that: The pH value is adjusted by adding ammonia or hydrochloric acid; petroleum ether and deionized water are used for washing.
7. The hydrophobic double-shell isocyanate self-healing microcapsule prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The appearance is spherical, the surface is flat and smooth, the particle size is 10-70μm, and the wall thickness is 0.67-4.69μm.
8. Use of the hydrophobic double-shell isocyanate type self-healing microcapsules according to claim 7 as self-healing fillers in coatings.
9. The use of the hydrophobic double-shell isocyanate self-repairing microcapsules according to claim 8 as self-repairing fillers, characterized in that: The mass fraction of the hydrophobic double-shell isocyanate type self-healing microcapsules in the coating is 3%-5%.