CN114507505A

CN114507505A - Mechanical nano sealant and preparation method thereof

Info

Publication number: CN114507505A
Application number: CN202210142220.2A
Authority: CN
Inventors: 文经建
Original assignee: Hunan Jinjian New Material Technology Co ltd
Current assignee: Hunan Jinjian New Material Technology Co ltd
Priority date: 2022-02-16
Filing date: 2022-02-16
Publication date: 2022-05-17

Abstract

The invention provides a mechanical nano sealant and a preparation method thereof, belonging to the technical field of sealants. The method comprises the following steps: s1, preparing a water phase; s2, preparing porous nano calcium carbonate hollow spheres; s3, preparing a catalyst solution; s4, preparing a barbed polydopamine-calcium carbonate composite hollow ball; s5, preparing a silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball; s6, preparing a modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball; s7, preparing the mechanical nano sealant. The mechanical nano sealant prepared by the invention is a silicone sealant, the modified silicon dioxide composite tape thorn-shaped polydopamine-calcium carbonate composite hollow ball is added, so that the thixotropic property, the mechanical property, the viscosity and the flame retardance of the sealant are obviously improved, and meanwhile, the added nano fibrous reinforcing agent can further enhance the mechanical property of the sealant, so that the mechanical nano sealant has wide application prospect.

Description

Mechanical nano sealant and preparation method thereof

Technical Field

The invention relates to the technical field of sealants, in particular to a mechanical nano sealant and a preparation method thereof.

Background

The silicone sealant is named condensed type room temperature vulcanized silicone Rubber (RTV), is composed of alpha, omega-dihydroxy polydimethylsiloxane as a basic polymer, a cross-linking agent, a catalyst, a filler and other characteristic additives, has excellent weather resistance, aging resistance and high and low temperature resistance, and is widely applied to the fields of machinery, buildings, automobiles, electronic appliances and the like. The silicone adhesive has excellent comprehensive performance which cannot be compared with other organic sealants, but the lower mechanical property of the silicone adhesive limits the application of the silicone adhesive in wider fields.

At present, the most effective way for improving the mechanical properties of silicone adhesive is filler reinforcement, which mainly comprises nano calcium carbonate and fumed silica, both of which are spherical structures, and the reinforcement principle is powder surface adsorption, i.e. the larger the specific surface area of the powder is, the better the reinforcement is, but the larger the specific surface area is, the larger the viscosity of the system is, and the system cannot be produced or used.

In addition, although the silicone adhesive has excellent characteristics such as aging resistance and high and low temperature resistance, the silicone adhesive needs to be treated on a vertical surface, and the sealant needs not to be drawn, flow and have small sag, so that the silicone adhesive needs to have good thixotropy, otherwise the surface of an adherend is easily polluted and the adhesive is wasted. Thixotropy is a rheological phenomenon in which viscosity and shear of a dispersion system change with time. The surface of the modified nano calcium carbonate is coated by organic substances, so that the compatibility and wettability between the modified nano calcium carbonate and organic materials are greatly improved, and the modified nano calcium carbonate can be applied to silicone adhesive to solve the problems of easy flowing, low strength, poor thixotropy and the like.

The nano calcium carbonate is a functional filler with the particle size of 20-100nm, is subjected to surface modification by using fatty acid or salt thereof, is widely applied to the manufacturing industry of room temperature vulcanized silicone sealant (RTV), has good processing performance and mechanical reinforcing performance, can partially or completely replace expensive white carbon black reinforcing filler, and has obvious economic benefit.

Patent CN201410011196.4 discloses a preparation method of nano calcium carbonate special for deoximation type silicone sealant. The surface treating agent adopted by the method is compounded by sodium stearate, palm oil, corn oil and silane coupling agents, has the characteristics of high thixotropy, high adhesion and the like, but has poor ultraviolet resistance of a treating agent system, particularly the silane coupling agents are easy to hydrolyze, and the nano calcium carbonate is easy to debond from a sealant base material in a damp and hot environment, so that the mechanical property is reduced.

Patent CN201110408668.6 discloses a preparation method of nano calcium carbonate SCC-2 special for silicone sealant. The method also uses sucrose as a crystal form control agent, adopts a normal-temperature activation technology of matching of fatty acid and coconut oil for surface treatment, and the product has a lower oil absorption value, a higher bulk specific gravity and better dispersibility in polymers. But also have poor uv and water resistance.

Disclosure of Invention

The invention aims to provide a mechanical nano sealant and a preparation method thereof, the prepared mechanical nano sealant is a silicone sealant, modified silicon dioxide composite tape thorn-shaped polydopamine-calcium carbonate composite hollow balls are added, so that the thixotropic property, the mechanical property, the viscosity and the flame retardance of the sealant are obviously improved, and meanwhile, the added nano fibrous reinforcing agent can further enhance the mechanical property of the sealant and has wide application prospect.

The technical scheme of the invention is realized as follows:

the invention provides a preparation method of a mechanical nano sealant, which comprises the following steps:

s1, preparation of a water phase: adding a pore-foaming agent into the calcium hydroxide saturated solution to obtain a water phase;

s2, preparing porous nano calcium carbonate hollow spheres: adding the water phase prepared in the step S1 into an organic solvent containing a surfactant, emulsifying, introducing carbon dioxide gas into the obtained emulsion, repeating the emulsifying and introducing steps, centrifuging, and drying to obtain the porous nano calcium carbonate hollow microspheres;

s3, preparing a catalyst solution: dissolving cobalt salt in Tris-HCl buffer solution to obtain catalyst solution;

s4, preparing the barbed polydopamine-calcium carbonate composite hollow ball: dissolving dopamine hydrochloride in water to form a uniform solution, adding the porous nano calcium carbonate hollow microspheres prepared in the step S2, stirring at room temperature, centrifuging, washing, dispersing in water, dropwise adding the catalyst solution prepared in the step S3, heating for reaction, centrifuging, washing and drying the product to obtain barbed poly-dopamine-calcium carbonate composite hollow spheres;

s5, preparing the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing the barbed polydopamine-calcium carbonate composite hollow spheres prepared in the step S4 into silica sol, heating for reaction, centrifuging, and washing to obtain silica composite barbed polydopamine-calcium carbonate composite hollow spheres;

s6, preparing the modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: adding the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow spheres prepared in the step S5 into an ethanol solution, adding a coupling agent, heating for reaction, centrifuging, washing and drying to obtain modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow spheres;

s7, preparing a mechanical nano sealant: and (4) uniformly mixing the alpha, omega-dihydroxy polydimethylsiloxane, the modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere prepared in the step S6 and the reinforcing agent, dehydrating, cooling to room temperature, adding the plasticizer, the crosslinking agent, the catalyst and the coupling agent, and stirring at low pressure to obtain the mechanical nano sealant.

As a further improvement of the present invention, in step S1, the pore-forming agent is selected from at least one of polyethylene glycol octyl phenyl ether and polyoxyethylene sorbitan fatty acid ester; the content of the pore-forming agent in the water phase is 1-3 wt%.

As a further improvement of the invention, the surfactant in step S2 is selected from at least one of span-80, glyceryl monostearate, monoalkyl ether phosphate, cetyl palmitate, starch octenyl succinate; the content of the surfactant in the organic solvent is 3-6 wt%; the organic solvent is at least one selected from toluene, xylene, cyclohexane, n-hexane, cyclopentane, petroleum ether, methyl formate, ethyl acetate, methyl acetate, dichloromethane, trichloromethane and chloroform; the rotation speed in the emulsification is 11000-; introducing carbon dioxide for 10-15min, and ventilating at 5-10L/min; the emulsification and aeration steps were repeated 3-7 times.

As a further improvement of the present invention, in step S3, the cobalt salt is at least one selected from cobalt chloride, cobalt sulfate and cobalt bromide; the pH value of the Tris-HCl buffer solution is 8-8.5, and Co in the catalyst solution²⁺The ion concentration is 1-2 wt%.

As a further improvement of the invention, the mass ratio of the dopamine hydrochloride to the porous nano calcium carbonate hollow microspheres in the step S4 is (2-3): 10; the stirring time at room temperature is 20-25 h; the heating temperature is 40-50 ℃, and the reaction time is 10-15 h.

As a further improvement of the present invention, the preparation method of the silica sol in step S5 is to mix water, ethanol, hydrochloric acid, and tetraethoxysilane uniformly to obtain a silica sol; the concentration of the hydrochloric acid is (1-3) mol/L; the mass ratio of the water, the ethanol, the hydrochloric acid and the ethyl orthosilicate is (3-5): (3-7): (0.1-0.5): (1-2); the heating reaction temperature is 50-70 ℃ and the time is 20-30 h.

As a further improvement of the invention, the coupling agent in the step S6 is a composite coupling agent, which comprises a silane coupling agent and a titanate coupling agent, and the mass ratio is (3-7): 2; the silane coupling agent is selected from at least one of KH550, KH560, KH570, KH580, KH590, KH6902 and KH 792; the titanate coupling agent is selected from at least one of KR-138S, KR-38S, KR-238S, TMC-201, TMC-102, TMC-101, TMC-311w, TMC-105, TMC-311, TMC-3, TMC-2, TMC-27 and TMC-4; preferably, the composition is a compound mixture of KH560 and KR-138S, and the mass ratio is 5: 2; the heating reaction temperature is 60-80 ℃, and the time is 3-5 h; the mass ratio of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow ball to the coupling agent is 100 (3-7).

As a further improvement of the present invention, in step S7, the mass ratio of the α, ω -dihydroxy polydimethylsiloxane, the modified silica composite barbed polydopamine-calcium carbonate composite hollow sphere, the reinforcing agent, the plasticizer, the crosslinking agent, the catalyst, and the coupling agent is 100: (3-7): (2-5): (3-6): (1-3): (0.5-1.5): (0.1-1); the dehydration temperature is 90-120 ℃, and the vacuum degree is 0.07-0.09 MPa; the low pressure is 0.07-0.09 MPa; the stirring time is 1-2 h; the reinforcing agent is selected from at least one of carbon nanofiber, carbon nanotube and nano glass fiber; the plasticizer is selected from at least one of dimethyl silicone oil, MDT silicone oil and monohydroxy silicone oil; the cross-linking agent is selected from at least one of methyl triacetoxysilane, propyl triacetoxysilane and vinyl triacetoxysilane; the catalyst is selected from at least one of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate or stannous octoate; the coupling agent is selected from at least one of methyl tributyrinoxime silane, vinyl tributyrinoxime silane, tetrabutoximino silane or phenyl tributyrinoxime silane.

As a further improvement of the invention, the method specifically comprises the following steps:

s1, preparation of a water phase: adding a pore-foaming agent into the calcium hydroxide saturated solution to obtain a water phase; wherein the content of the pore-foaming agent is 1-3 wt%;

s2, preparing porous nano calcium carbonate hollow spheres: adding the water phase prepared in the step S1 into an organic solvent containing 3-6 wt% of a surfactant, emulsifying at the rotation speed of 11000-13000r/min for 5-10min, introducing carbon dioxide gas into the obtained emulsion for 10-15min at the ventilation rate of 5-10L/min, repeating the emulsifying and ventilating steps for 3-7 times, centrifuging, and drying to obtain the porous nano calcium carbonate hollow microspheres;

s3, preparing a catalyst solution: dissolving cobalt salt in Tris-HCl buffer solution with the pH value of 8-8.5 to obtain catalyst solution, wherein Co is²⁺The ion concentration is 1-2 wt%;

s4, preparing the barbed polydopamine-calcium carbonate composite hollow ball: dissolving 2-3 parts by weight of dopamine hydrochloride in water to form a uniform solution, adding 10 parts by weight of the porous nano calcium carbonate hollow microspheres prepared in the step S2, stirring at room temperature for 20-25h, centrifuging, washing, dispersing in water, dropwise adding 1-3 parts by weight of the catalyst solution prepared in the step S3, heating to 40-50 ℃, reacting for 10-15h, centrifuging, washing and drying the product to obtain the spiny polydopamine-calcium carbonate composite hollow spheres;

s5, preparing the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing the barbed polydopamine-calcium carbonate composite hollow spheres prepared in the step S4 into silica sol, heating to 50-70 ℃, reacting for 20-30h, centrifuging, and washing to obtain the silica composite barbed polydopamine-calcium carbonate composite hollow spheres; the preparation method of the silica sol comprises the steps of uniformly mixing 3-5 parts by weight of water, 3-7 parts by weight of ethanol, 0.1-0.5 part by weight of 1-3mol/L hydrochloric acid and 1-2 parts by weight of ethyl orthosilicate to obtain the silica sol;

s6, preparing the modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: adding 100 parts by weight of the silicon dioxide composite strip spiny polydopamine-calcium carbonate composite hollow spheres prepared in the step S5 into an ethanol solution, adding 3-7 parts by weight of a coupling agent, heating to 60-80 ℃, reacting for 3-5h, centrifuging, washing, and drying to obtain modified silicon dioxide composite strip spiny polydopamine-calcium carbonate composite hollow spheres; the coupling agent is a composite coupling agent and comprises a silane coupling agent and a titanate coupling agent, and the mass ratio of the silane coupling agent to the titanate coupling agent is (3-7): 2;

s7, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 3-7 parts by weight of the modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere prepared in the step S6, 2-5 parts by weight of reinforcing agent, dehydrating at the temperature of 90-120 ℃ and the vacuum degree of 0.07-0.09MPa, cooling to room temperature, adding 3-6 parts by weight of plasticizer, 1-3 parts by weight of cross-linking agent, 0.5-1.5 parts by weight of catalyst and 0.1-1 part by weight of coupling agent, and stirring for 1-2 hours under the pressure of 0.07-0.09MPa to obtain the mechanical nano sealant.

The invention further protects the mechanical nano sealant prepared by the preparation method.

The invention has the following beneficial effects: in the presence of a surfactant, mixing and emulsifying a calcium hydroxide saturated solution and an organic solvent to form uniform and stable single-phase microemulsion, forming a calcium carbonate shell layer on the surface of a microemulsion liquid drop when carbon dioxide is introduced, and forming uniform and porous calcium carbonate nano hollow microspheres under the action of a pore-forming agent; after the sealant is added, a good reinforcing effect can be achieved, and the mechanical property and the thixotropic property of the sealant are obviously improved;

further, after a dopamine hydrochloride solution enters the porous calcium carbonate nano hollow microsphere, the dopamine hydrochloride solution exists in the porous calcium carbonate nano hollow microsphere through washing, after the dopamine hydrochloride solution is added into a solution containing a catalyst, the catalyst induces dopamine to grow outwards in a pore channel of the porous calcium carbonate nano microsphere so as to form a long spine, the spine mainly comprises polydopamine, and after a small amount of silicon dioxide is compounded subsequently, part of the polydopamine is exposed;

further, the prepared spiny polydopamine-calcium carbonate composite hollow sphere is added into silica sol, and the surface of the polydopamine is provided with more amino and hydroxyl groups, so that the polydopamine is easy to be in hydrogen bond connection with the silica sol, and a silica layer is compounded on the surface of the microsphere, so that the performance of the microsphere is enhanced, and the content of silica is low, so that part of the surface of the polydopamine is exposed; under the acidic condition, the precursor silica sol has a slow sol-gel reaction rate, and is not easy to generate impurities in a bulk phase, so that redundant silica particles are not formed, and the sol-gel reaction is uniformly carried out in the polydopamine and on part of the surface of the polydopamine; after the silicon dioxide compounded nano particles are added into the silicone sealant, the mechanical property of the matrix can be obviously improved;

subsequently, the prepared silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere is further modified by a composite coupling agent, a silane coupling agent and a titanate coupling agent are modified on the surfaces of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere, alkyl groups of the titanate coupling agent and the silane coupling agent are partially hydrolyzed and combined with hydroxyl groups on the surface of the microsphere, so that the surface of the nano microsphere is hydrophobic, the other end of the nano microsphere can be further wound with macromolecular chains in a silicone sealant matrix in a subsequent reaction, the dispersity and the compatibility of the microsphere in the matrix are improved, meanwhile, the epoxy structure of KH560 can improve the viscosity and the mechanical property of the sealant, and the phosphorus-containing group of KR-138S can improve the flame retardance of the sealant; the synergistic modification of the compounded mixture of KH560 and KR-138S can not only improve the dispersibility of the microspheres in the matrix, but also enhance the toughness, viscosity and flame retardance of the prepared sealant;

in addition, the reinforcing agent of the silicone sealant is a nano fibrous filler, the reinforcing filler can be adsorbed on the surface of the modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow ball with a spherical structure, so that the reinforcing effect is enhanced, and meanwhile, the reinforcing filler can also serve as a 'reinforcing bar' to greatly improve the mechanical strength of the silicone sealant;

the mechanical nano sealant prepared by the invention is a silicone sealant, the modified silicon dioxide composite tape thorn-shaped polydopamine-calcium carbonate composite hollow ball is added, so that the thixotropic property, the mechanical property, the viscosity and the flame retardance of the sealant are obviously improved, and meanwhile, the added nano fibrous reinforcing agent can further enhance the mechanical property of the sealant, so that the mechanical nano sealant has wide application prospect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is an SEM image of a modified silica composite strip thorn-shaped polydopamine-calcium carbonate composite hollow sphere prepared in example 1 of the invention;

fig. 2 is a TEM image of the modified silica composite barbed polydopamine-calcium carbonate composite hollow sphere prepared in example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The carbon nano tube is purchased from Shanghai lane field nanometer material Co., Ltd, has a particle size of 8nm, a length of 10-15nm and a water content of less than 0.05%.

The nano calcium carbonate added in the comparative example 5 is purchased from Guangxi Virbus calcium science and technology Limited liability company, model number is CC-J30, and the specific surface area is 25 +/-2 m²The whiteness is more than 95 percent, the moisture is less than 0.35 percent, the pH value is 8.0 to 9.5, and the average grain diameter is 60 to 90 nm.

Example 1

The embodiment provides a preparation method of a mechanical nano sealant, which specifically comprises the following steps:

s1, preparation of a water phase: adding polyethylene glycol octyl phenyl ether into the calcium hydroxide saturated solution to obtain a water phase; wherein the content of the polyethylene glycol octyl phenyl ether is 1 wt%;

s2, preparing porous nano calcium carbonate hollow spheres: adding 50 parts by weight of the water phase prepared in the step S1 into 100 parts by weight of toluene containing 3 wt% of octenyl succinate starch, emulsifying, wherein the emulsifying rotation speed is 11000r/min, the emulsifying time is 5min, introducing carbon dioxide gas into the obtained emulsion, the introducing time of carbon dioxide is 10min, the ventilation amount is 5L/min, repeating the emulsifying and ventilation steps for 3 times, centrifuging at 3000r/min for 15min, and drying at 70 ℃ for 2h to obtain the porous nano calcium carbonate hollow microspheres;

s3, preparing a catalyst solution: dissolving cobalt bromide in Tris-HCl buffer solution with the pH value of 8 to obtain catalyst solution, wherein Co is²⁺The ion concentration is 1 wt%;

s4, preparing the barbed polydopamine-calcium carbonate composite hollow ball: dissolving 2 parts by weight of dopamine hydrochloride in water to form a uniform solution, adding 10 parts by weight of the porous nano calcium carbonate hollow microspheres prepared in the step S2, stirring at room temperature for 20 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, uniformly dispersing in 100 parts by weight of water, dropwise adding 1 part by weight of the catalyst solution prepared in the step S3, heating to 40 ℃ for reaction for 10 hours, centrifuging the product at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain the barbed poly dopamine-calcium carbonate composite hollow spheres;

s5, preparing the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing 100 parts by weight of the barbed polydopamine-calcium carbonate composite hollow sphere prepared in the step S4 into 100 parts by weight of silica sol, heating to 50 ℃ for reaction for 20 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain a silica composite barbed polydopamine-calcium carbonate composite hollow sphere;

the preparation method of the silica sol comprises the steps of uniformly mixing 3 parts by weight of water, 3 parts by weight of ethanol, 0.1 part by weight of 1mol/L hydrochloric acid and 1 part by weight of ethyl orthosilicate to obtain the silica sol;

s6, preparing the modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: adding 100 parts by weight of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres prepared in the step S5 into an ethanol solution, adding 3 parts by weight of a coupling agent, heating to 60 ℃, reacting for 3 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres; FIG. 1 is an SEM image of the prepared modified silica composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere, and as can be seen from the SEM image, a large number of protrusions are formed on the surface of the microsphere, and the particle size is 80-150 nm; fig. 2 is a TEM image of the prepared modified silica composite barbed polydopamine-calcium carbonate composite hollow sphere, and it can be seen from the TEM image that a large number of spikes are formed on the surface of the microsphere, and the microsphere has a hollow structure.

The coupling agent is a composite coupling agent and comprises a silane coupling agent KH560 and a titanate coupling agent KR-138S, and the mass ratio is 3: 2;

s7, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 3 parts by weight of the modified silicon dioxide composite tape-thorn-shaped polydopamine-calcium carbonate composite hollow sphere prepared in the step S6 and 2 parts by weight of carbon nano tube, dehydrating at the temperature of 90 ℃ and the vacuum degree of 0.07MPa, cooling to room temperature, adding 3 parts by weight of MDT silicone oil, 1 part by weight of propyl triacetoxysilane, 0.5 part by weight of stannous octoate and 0.1 part by weight of tetrabutylketoxime silane, and stirring for 1 hour under the pressure of 0.07MPa to obtain the mechanical nano sealant.

Example 2

s1, preparation of a water phase: adding polyoxyethylene sorbitan fatty acid ester into the calcium hydroxide saturated solution to obtain a water phase; wherein the polyoxyethylene sorbitan fatty acid ester content is 3 wt%;

s2, preparing porous nano calcium carbonate hollow spheres: adding 50 parts by weight of the water phase prepared in the step S1 into 100 parts by weight of cyclohexane containing 6 wt% of glyceryl monostearate, emulsifying, wherein the emulsifying rotation speed is 13000r/min, the emulsifying time is 10min, introducing carbon dioxide gas into the obtained emulsion, the introducing time of carbon dioxide is 15min, the ventilation amount is 10L/min, repeating the emulsifying and ventilation steps for 7 times, centrifuging at 3000r/min for 15min, and drying at 70 ℃ for 2h to obtain the porous nano calcium carbonate hollow microspheres;

s3, preparing a catalyst solution: dissolving cobalt sulfate in Tris-HCl buffer solution with the pH value of 8.5 to obtain catalyst solution, wherein Co is²⁺The ion concentration is 2 wt%;

s4, preparing the barbed polydopamine-calcium carbonate composite hollow ball: dissolving 3 parts by weight of dopamine hydrochloride in water to form a uniform solution, adding 10 parts by weight of the porous nano calcium carbonate hollow microspheres prepared in the step S2, stirring at room temperature for 25 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, uniformly dispersing in 100 parts by weight of water, dropwise adding 3 parts by weight of the catalyst solution prepared in the step S3, heating to 50 ℃ for reaction for 15 hours, centrifuging the product at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain the barbed poly dopamine-calcium carbonate composite hollow spheres;

s5, preparing the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing 100 parts by weight of the barbed poly-dopamine-calcium carbonate composite hollow spheres prepared in the step S4 into 100 parts by weight of silica sol, heating to 70 ℃ for reaction for 30 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain silica composite barbed poly-dopamine-calcium carbonate composite hollow spheres;

the preparation method of the silica sol comprises the steps of uniformly mixing 5 parts by weight of water, 7 parts by weight of ethanol, 0.5 part by weight of 3mol/L hydrochloric acid and 2 parts by weight of ethyl orthosilicate to obtain the silica sol;

s6, preparing the modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: adding 100 parts by weight of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres prepared in the step S5 into an ethanol solution, adding 7 parts by weight of a coupling agent, heating to 80 ℃, reacting for 5 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres;

the coupling agent is a composite coupling agent and comprises a silane coupling agent KH560 and a titanate coupling agent KR-138S, and the mass ratio is 7: 2;

s7, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 7 parts by weight of modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow spheres prepared in the step S6 and 5 parts by weight of carbon nano tubes, dehydrating at the temperature of 120 ℃ and the vacuum degree of 0.09MPa, cooling to room temperature, adding 6 parts by weight of monohydroxy silicone oil, 3 parts by weight of vinyl triacetoxysilane, 1.5 parts by weight of dibutyl tin diacetate and 1 part by weight of methyl tributyl ketoxime silane, and stirring for 2 hours under the pressure of 0.09MPa to obtain the mechanical nano sealant.

Example 3

s1, preparation of a water phase: adding polyoxyethylene sorbitan fatty acid ester into the calcium hydroxide saturated solution to obtain a water phase; wherein the content of the polyoxyethylene sorbitan fatty acid ester is 2 wt%;

s2, preparing porous nano calcium carbonate hollow spheres: adding 50 parts by weight of the water phase prepared in the step S1 into 100 parts by weight of petroleum ether containing 4.5 wt% of span-80, emulsifying, wherein the emulsifying rotation speed is 12000r/min, the emulsifying time is 7min, introducing carbon dioxide gas into the obtained emulsion, the introducing time of carbon dioxide is 12min, the ventilation volume is 7L/min, repeating the emulsifying and ventilation steps for 5 times, centrifuging at 3000r/min for 15min, and drying at 70 ℃ for 2h to obtain the porous nano calcium carbonate hollow microspheres;

s3, preparing a catalyst solution: dissolving cobalt chloride in Tris-HCl buffer solution with the pH value of 8.2 to obtain catalyst solution, wherein Co is²⁺The ion concentration was 1.5 wt%;

s4, preparing the barbed polydopamine-calcium carbonate composite hollow ball: dissolving 2.5 parts by weight of dopamine hydrochloride in water to form a uniform solution, adding 10 parts by weight of the porous nano calcium carbonate hollow microspheres prepared in the step S2, stirring at room temperature for 22 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, uniformly dispersing in 100 parts by weight of water, dropwise adding 2 parts by weight of the catalyst solution prepared in the step S3, heating to 45 ℃ for reaction for 12 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain the barbed poly-dopamine-calcium carbonate composite hollow spheres;

s5, preparing the silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing 100 parts by weight of the barbed poly-dopamine-calcium carbonate composite hollow spheres prepared in the step S4 into 100 parts by weight of silica sol, heating to 60 ℃ for reaction for 25 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain silica composite barbed poly-dopamine-calcium carbonate composite hollow spheres;

the preparation method of the silica sol comprises the steps of uniformly mixing 4 parts by weight of water, 5 parts by weight of ethanol, 0.3 part by weight of 2mol/L hydrochloric acid and 1.5 parts by weight of ethyl orthosilicate to obtain the silica sol;

s6, preparing the modified silicon dioxide composite strip thorn-shaped polydopamine-calcium carbonate composite hollow ball: adding 100 parts by weight of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres prepared in the step S5 into an ethanol solution, adding 5 parts by weight of a coupling agent, heating to 70 ℃, reacting for 4 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain modified silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow spheres;

the coupling agent is a composite coupling agent and comprises a silane coupling agent KH560 and a titanate coupling agent KR-138S, and the mass ratio is 5: 2;

s7, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 5 parts by weight of the modified silicon dioxide composite barbed polydopamine-calcium carbonate composite hollow sphere prepared in the step S6 and 3.5 parts by weight of carbon nano tube, dehydrating at the temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributyrinthine, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Example 4

Compared with example 3, the coupling agent is silane coupling agent KH560, and other conditions are not changed.

Example 5

Compared with the example 3, the coupling agent is titanate coupling agent KR-138S, and other conditions are not changed.

Example 6

Compared with the embodiment 3, the coupling agent is a silane coupling agent KH550 and a titanate coupling agent KR-138S, and the mass ratio is 5:2, other conditions are not changed.

Example 7

Compared with the embodiment 3, the coupling agent is a silane coupling agent KH560 and a titanate coupling agent TMC-105, and the mass ratio is 5:2, other conditions are not changed.

Comparative example 1

Compared with example 3, in step S1, no pore-forming agent polyoxyethylene sorbitan fatty acid ester was added, and other conditions were not changed.

The method specifically comprises the following steps:

s1, preparation of a water phase: preparing a calcium hydroxide saturated solution as a water phase;

Comparative example 2

Steps S3 and S4 were not performed, and other conditions were not changed, as compared with example 3.

The method specifically comprises the following steps:

s3, preparing the silicon dioxide composite calcium carbonate hollow spheres: dispersing 100 parts by weight of the porous nano calcium carbonate hollow microspheres prepared in the step S2 into 100 parts by weight of silica sol, heating to 60 ℃ for reaction for 25 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain silica composite calcium carbonate hollow spheres;

s4, preparing the modified silicon dioxide composite calcium carbonate hollow spheres: adding 100 parts by weight of the hollow spheres of the silicon dioxide composite calcium carbonate prepared in the step S3 into an ethanol solution, adding 5 parts by weight of a coupling agent, heating to 70 ℃ for reaction for 4 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain modified hollow spheres of the silicon dioxide composite calcium carbonate;

s5, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 5 parts by weight of the modified silicon dioxide composite calcium carbonate hollow spheres prepared in the step S4 and 3.5 parts by weight of carbon nano tubes, dehydrating at the dehydration temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributyrinoxime silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Comparative example 3

Step S5 was not performed, and other conditions were not changed, as compared with example 3.

The method specifically comprises the following steps:

s1, preparing a water phase: adding polyoxyethylene sorbitan fatty acid ester into the calcium hydroxide saturated solution to obtain a water phase; wherein the content of the polyoxyethylene sorbitan fatty acid ester is 2 wt%;

s5, preparing the modified spiny polydopamine-calcium carbonate composite hollow sphere: adding 100 parts by weight of the barbed poly-dopamine-calcium carbonate composite hollow spheres prepared in the step S4 into an ethanol solution, adding 5 parts by weight of a coupling agent, heating to 70 ℃ for reaction for 4 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain modified barbed poly-dopamine-calcium carbonate composite hollow spheres;

s6, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 5 parts by weight of the modified barbed polydopamine-calcium carbonate composite hollow sphere prepared in the step S6 and 3.5 parts by weight of carbon nano tube, dehydrating at the dehydration temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributyrine oxime silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Comparative example 4

Step S6 was not performed, and other conditions were not changed as compared with example 3.

The method specifically comprises the following steps:

s3. preparation of catalyst solution: dissolving cobalt chloride in Tris-HCl buffer solution with the pH value of 8.2 to obtain catalyst solution, wherein Co is²⁺The ion concentration was 1.5 wt%;

s5, preparing the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow ball: dispersing 100 parts by weight of the barbed poly-dopamine-calcium carbonate composite hollow spheres prepared in the step S4 into 100 parts by weight of silica sol, heating to 60 ℃ for reaction for 25 hours, centrifuging at 3000r/min for 15 minutes, washing with deionized water, and drying at 70 ℃ for 2 hours to obtain silica composite barbed poly-dopamine-calcium carbonate composite hollow spheres;

s6, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 5 parts by weight of the silicon dioxide composite barbed polydopamine-calcium carbonate composite hollow sphere prepared in the step S5 and 3.5 parts by weight of carbon nano tube, dehydrating at the dehydration temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributyrine oxime silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Comparative example 5

Compared with the embodiment 3, the modified silica composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere in the step S7 is replaced by the commonly purchased nano calcium carbonate, and other conditions are not changed.

The method specifically comprises the following steps:

preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane, 5 parts by weight of nano calcium carbonate and 3.5 parts by weight of carbon nano tube, dehydrating at the temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of dimethyl silicone oil, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributoxy silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Comparative example 6

In step S7, the carbon nanotubes as the reinforcing agent were not added, and other conditions were not changed, as compared with example 3.

The method specifically comprises the following steps:

s7, preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane and 8.5 parts by weight of the modified silicon dioxide composite barbed polydopamine-calcium carbonate composite hollow sphere prepared in the step S6, dehydrating at the temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributylketoxime silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Comparative example 7

Compared with the example 3, the modified silica composite belt thorn-shaped polydopamine-calcium carbonate composite hollow sphere is not added in the step S7, and other conditions are not changed.

The method specifically comprises the following steps:

preparing a mechanical nano sealant: uniformly mixing 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane and 8.5 parts by weight of carbon nano tube, dehydrating at the dehydration temperature of 105 ℃ and the vacuum degree of 0.08MPa, cooling to room temperature, adding 5 parts by weight of simethicone, 2 parts by weight of propyl triacetoxysilane, 1 part by weight of dibutyltin dilaurate and 0.5 part by weight of vinyl tributyrinoxime silane, and stirring for 1.5 hours under the pressure of 0.08MPa to obtain the mechanical nano sealant.

Test example 1 adhesion Performance test

The mechanical nano-sealants prepared in examples 1-7 and comparative examples 1-7 of the invention are carried out according to the requirements of GB 16776-.

TABLE 1

As can be seen from the above table, the mechanical nano sealant prepared in the embodiments 1-3 of the present invention has good adhesion property.

Test example 2

The mechanical nano-sealants prepared in examples 1-7 and comparative examples 1-7 of the invention are subjected to performance detection according to GB16776-2005, and the results are shown in the following tables 2 and 3.

TABLE 2

TABLE 3

As can be seen from the above table, the mechanical nano sealant prepared in the embodiments 1-3 of the invention has good mechanical properties, flame retardant properties and good comprehensive properties.

Test example 3

The mechanical nano-sealants prepared in examples 1 to 7 and comparative examples 1 to 7 were subjected to thixotropic property test by the following method:

(1) extrusion tail supporting test method:

the mechanical nano sealant is pressurized to 200 kg-force/cm by a high-pressure pump²The sealant was extruded through a circular nozzle having a diameter of 2 mm. And observing whether the sealant has a tail supporting phenomenon when the gun is retracted after the glue extrusion is finished, if the tail supporting length is more than or equal to 3cm, determining that the sealant is seriously trailing, and if the tail supporting length is not more than 1cm, determining that the sealant is qualified.

(2) The anti-sagging performance testing method comprises the following steps:

and (3) coating the mechanical nano sealant on an electrophoresis steel plate to form a coating with the thickness of 5mm, vertically placing, observing the vertical flow condition of the coating, and calculating (mm) according to the overall flow distance after 20 min.

The results are shown in Table 4

TABLE 4

Group of	Anti-sagging performance (mm)	Extrusion Properties (trailing phenomenon)
			Example 1	Does not flow down	Qualified
Example 2	Does not flow down	Qualified
			Example 3	Does not flow down	Qualified
Example 4	Does not flow down	Qualified
			Example 5	Does not flow down	Qualified
Example 6	Does not flow down	Qualified
			Example 7	Does not flow down	Qualified
Comparative example 1	Flow 4-7mm	Tailing
			Comparative example 2	Flowing for 6-8mm	Severe tailing
Comparative example 3	Does not flow down	Qualified
			Comparative example 4	Flow 3-6	Tailing
Comparative example 5	Flows for 6-8mm	Severe tailing
			Comparative example 6	Does not flow down	Qualified
Comparative example 7	Flowing for 6-8mm	Severe tailing

As can be seen from the above table, the mechanical nano-sealants prepared in the embodiments 1 to 3 of the present invention have good thixotropic properties.

Compared with the embodiment 3, the embodiments 4 and 5 have the advantages that the coupling agent is silane coupling agent KH560 or titanate coupling agent KR-138S, the adhesive property of the embodiment 4 is obviously reduced, the flame retardant property of the embodiment 5 is obviously reduced, meanwhile, the mechanical properties of the embodiments 4 and 5 are reduced, the prepared silicon dioxide composite barbed polydopamine-calcium carbonate composite hollow sphere is further modified by the composite coupling agent, the silane coupling agent and the titanate coupling agent are modified on the surface of the silicon dioxide composite barbed polydopamine-calcium carbonate composite hollow sphere, the alkyl parts of the titanate coupling agent and the silane coupling agent are hydrolyzed and combined with the hydroxyl on the surface of the microsphere, so that the surface of the nano microsphere is hydrophobic, the other end of the nano microsphere can be further wound with macromolecular chains in a silicone sealant matrix in the subsequent reaction, the dispersibility and the compatibility of the microsphere in the matrix are improved, and meanwhile, the epoxy structure of KH560 can improve the viscosity and the mechanical properties of the sealant, the phosphorus-containing group of KR-138S can improve the flame retardance of the sealant; the synergistic modification of the compounded mixture of KH560 and KR-138S can not only improve the dispersibility of the microspheres in the matrix, but also enhance the toughness, viscosity and flame retardance of the prepared sealant.

Compared with the embodiment 3, the coupling agents in the embodiments 6 and 7 are the compound mixture of a silane coupling agent KH550 and a titanate coupling agent KR-138S or the compound mixture of the silane coupling agent KH560 and a titanate coupling agent TMC-105, the mechanical property, the adhesive property and the flame retardant property of the sealant are slightly reduced, the viscosity and the mechanical property of the sealant can be improved by the epoxy structure of the KH560, and the flame retardant property of the sealant can be improved by the phosphorus-containing group of the KR-138S; the synergistic modification of the compounded mixture of KH560 and KR-138S can not only improve the dispersibility of the microspheres in the matrix, but also enhance the toughness, viscosity and flame retardance of the prepared sealant.

Compared with example 3, in step S1, no porogen is added, so that no spikes are formed in comparative example 1, the calcium carbonate microspheres are covered by polydopamine, and the polydopamine on the surface is covered by silica, so that the thixotropic property and the mechanical property of the microspheres are reduced. In the presence of a surfactant, mixing and emulsifying a calcium hydroxide saturated solution and an organic solvent to form uniform and stable single-phase microemulsion, forming a calcium carbonate shell layer on the surface of a microemulsion liquid drop when carbon dioxide is introduced, and forming uniform and porous calcium carbonate nano hollow microspheres under the action of a pore-forming agent; after the sealant is added, the composite material can play a good reinforcing role, and the mechanical property and the thixotropic property of the sealant are obviously improved.

Compared with the example 3, the comparative example 2 does not carry out the steps S3 and S4, so that the thixotropic property of the sealant is obviously reduced, and the mechanical property is reduced; the surface of the porous calcium carbonate nano hollow microsphere is not provided with polydopamine spikes, the calcium carbonate nano microsphere is coated with silicon dioxide, dopamine hydrochloride solution enters the porous calcium carbonate nano hollow microsphere and is washed, so that the dopamine hydrochloride solution exists in the porous calcium carbonate nano hollow microspheres, and after the dopamine hydrochloride solution is added into the solution containing the catalyst, the catalyst induces dopamine to grow outwards in the pore canal of the porous calcium carbonate nano microsphere, thereby forming long sharp spines, the main component of the spine is polydopamine, after a small amount of silicon dioxide is compounded subsequently, part of the polydopamine is exposed, the polydopamine contains a large amount of hydroxyl and amino structures, and surface hydrogen bonds generate thixotropy to prevent the tail supporting phenomenon, meanwhile, macromolecular chains of organic macromolecules are mutually wound to form a net structure, so that the sagging phenomenon is prevented, and the thixotropic property of the sealant can be obviously improved.

Compared with the embodiment 3, the mechanical property of the composite hollow ball is obviously reduced without the step S5, the prepared spiny polydopamine-calcium carbonate composite hollow ball is added into silica sol, the surface of the polydopamine has more amino and hydroxyl, so that the polydopamine is easy to be bonded with the silica sol through hydrogen bond, a silica layer is compounded on the surface of the microsphere, the property of the microsphere is enhanced, the content of the silica is lower, and the surface part of the polydopamine is exposed; under the acidic condition, the precursor silica sol has a slow sol-gel reaction rate, and is not easy to generate impurities in a bulk phase, so that redundant silica particles are not formed, and the sol-gel reaction is uniformly carried out in the polydopamine and on part of the surface of the polydopamine; after the silicon dioxide compounded nano particles are added into the silicone sealant, the mechanical property of the matrix can be obviously improved.

Comparative example 4, without performing step S6, had a reduced mechanical properties and combination of properties compared to example 3, because the unmodified microspheres were not uniformly dispersed, resulting in reduced properties and reduced adhesion and flame retardancy.

Compared with the example 3, the modified silicon dioxide composite barbed poly dopamine-calcium carbonate composite hollow sphere in the step S7 is replaced by the commonly purchased nano calcium carbonate, and the mechanical property and the comprehensive property of the modified silicon dioxide composite barbed poly dopamine-calcium carbonate composite hollow sphere are obviously reduced.

Compared with the example 3, in the comparative examples 6 and 7, the reinforcing agent carbon nano tube or the modified silica composite barbed poly-dopamine-calcium carbonate composite hollow sphere which is not added in the step S7 has obviously reduced mechanical properties, so that the nano fibrous filler can be adsorbed on the surface of the prepared modified silica composite barbed poly-dopamine-calcium carbonate composite hollow sphere with a spherical structure, thereby enhancing the reinforcing effect, and meanwhile, the nano fibrous filler can also serve as a 'reinforcing bar' to greatly improve the mechanical strength of the silicone sealant.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.

Claims

1. The preparation method of the mechanical nano sealant is characterized by comprising the following steps:

2. The method for preparing a mechanical nano sealant according to claim 1, wherein in step S1, the pore-forming agent is selected from at least one of polyethylene glycol octyl phenyl ether and polyoxyethylene sorbitan fatty acid ester; the content of the pore-forming agent in the water phase is 1-3 wt%.

3. The method for preparing the mechanical nano sealant according to the claim 1, wherein the surfactant in the step S2 is selected from at least one of span-80, glycerin monostearate, monoalkyl ether phosphate, cetyl palmitate, starch octenyl succinate; the content of the surfactant in the organic solvent is 3-6 wt%; the organic solvent is at least one selected from toluene, xylene, cyclohexane, n-hexane, cyclopentane, petroleum ether, methyl formate, ethyl acetate, methyl acetate, dichloromethane, trichloromethane and chloroform; the rotation speed in the emulsification is 11000-; introducing carbon dioxide for 10-15min, and ventilating at 5-10L/min; the emulsification and aeration steps were repeated 3-7 times.

4. The method for preparing mechanical nano sealant according to claim 1, wherein the cobalt salt in step S3 is selected from at least one of cobalt chloride, cobalt sulfate and cobalt bromide; the pH value of the Tris-HCl buffer solution is 8-8.5, and Co in the catalyst solution²⁺The ion concentration is 1-2 wt%.

5. The preparation method of the mechanical nano sealant according to claim 1, wherein the mass ratio of the dopamine hydrochloride to the porous nano calcium carbonate hollow microspheres in step S4 is (2-3): 10; the stirring time at room temperature is 20-25 h; the heating temperature is 40-50 ℃, and the reaction time is 10-15 h.

6. The method for preparing the mechanical nano sealant according to claim 1, wherein the method for preparing the silica sol in the step S5 is to uniformly mix water, ethanol, hydrochloric acid and tetraethoxysilane to obtain the silica sol; the concentration of the hydrochloric acid is (1-3) mol/L; the mass ratio of the water, the ethanol, the hydrochloric acid and the ethyl orthosilicate is (3-5): (3-7): (0.1-0.5): (1-2); the heating reaction temperature is 50-70 ℃ and the time is 20-30 h.

7. The preparation method of the mechanical nano sealant as claimed in claim 1, wherein the coupling agent in step S6 is a composite coupling agent comprising a silane coupling agent and a titanate coupling agent, and the mass ratio is (3-7): 2; the silane coupling agent is selected from at least one of KH550, KH560, KH570, KH580, KH590, KH6902 and KH 792; the titanate coupling agent is selected from at least one of KR-138S, KR-38S, KR-238S, TMC-201, TMC-102, TMC-101, TMC-311w, TMC-105, TMC-311, TMC-3, TMC-2, TMC-27 and TMC-4; preferably, the composition is a compound mixture of KH560 and KR-138S, and the mass ratio is 5: 2; the heating reaction temperature is 60-80 ℃, and the time is 3-5 h; the mass ratio of the silicon dioxide composite belt thorn-shaped polydopamine-calcium carbonate composite hollow ball to the coupling agent is 100 (3-7).

8. The method for preparing the mechanical nano sealant according to claim 1, wherein in step S7, the mass ratio of the α, ω -dihydroxy polydimethylsiloxane, the modified silica composite tape-needled polydopamine-calcium carbonate composite hollow sphere, the reinforcing agent, the plasticizer, the crosslinking agent, the catalyst and the coupling agent is 100: (3-7): (2-5): (3-6): (1-3): (0.5-1.5): (0.1-1); the dehydration temperature is 90-120 ℃, and the vacuum degree is 0.07-0.09 MPa; the low pressure is 0.07-0.09 MPa; the stirring time is 1-2 h; the reinforcing agent is selected from at least one of carbon nanofiber, carbon nanotube and nano glass fiber; the plasticizer is selected from at least one of dimethyl silicone oil, MDT silicone oil and monohydroxy silicone oil; the cross-linking agent is selected from at least one of methyl triacetoxysilane, propyl triacetoxysilane and vinyl triacetoxysilane; the catalyst is selected from at least one of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate or stannous octoate; the coupling agent is selected from at least one of methyl tributyrinoxime silane, vinyl tributyrinoxime silane, tetrabutoximino silane or phenyl tributyrinoxime silane.

9. The preparation method of the mechanical nano sealant according to any one of claims 1 to 8, which is characterized by comprising the following steps:

10. A mechanical nano-sealant prepared by the preparation method according to any one of claims 1 to 9.