Self-repairing micro-capsule and preparation method and application thereof

Self-repairing microcapsule and its preparation method and application technical field

[0001] The present invention relates to the technical field of metal anticorrosion, and in particular to a self-healing microcapsule and its preparation method and application.

Background technique

[0002] Corrosion of metals is a phenomenon in which metals are destroyed by chemical or electrochemical effects of environmental media. The corrosive effects of metals, especially corrosion fatigue and stress corrosion, usually cause catastrophic major accidents. One of the most effective solutions is to apply an anti-corrosion coating on the metal surface. However, when the anti-corrosion coating is affected by environmental or mechanical forces during use, micro-cracks will occur. The propagation and expansion of micro-cracks accelerate the damage, peeling and shedding of the surface coating of the metal substrate, making the metal surface impossible. Get effective protection. How to effectively carry out metal corrosion protection through coating self-healing technology is a cutting-edge research topic.

[0003] Imitate the principle of biological self-repair function, design and prepare a coating with self-repair function, so that the coating can self-repair the damaged part, can eliminate hidden dangers, prolong the service life of coating materials, and realize the effect on metal substrates. Long-term corrosion protection. As an important branch of intelligent coating, self-healing coating is a relatively new field developed on the basis of material self-healing. It has a wide range of conductive coatings, scratch-resistant coatings, anti-corrosion coatings and other fields. Application, especially in some anti-corrosion coatings that require long life, difficult to maintain and are in harsh corrosive environments (such as towers and blades of wind energy generators, offshore drilling platforms, ships, railways, bridges, oil pipelines, and some harsh environments such as Special adhesive coatings applied in aerospace, military and marine applications are in urgent need. The application of the capsule-type self-healing technology to the field of self-healing metal anticorrosive coatings is a brand-new subject, which is currently attracting wide attention from scholars at home and abroad. The basic theoretical research on this technology will bring huge economic development to the development of the national economy. Benefits and development space have broad application prospects.

[0004] In 2001, White and other researchers first proposed the concept of microcapsule self-repair. In the past 20 years, microcapsule self-repair technology has provided an effective solution for metal corrosion protection. The self-healing mechanism of microcapsules is: adding microcapsules to the coating matrix, when the coating is damaged, the microcapsules rupture and release the repairing agent to repair the damage, thereby protecting the integrity of the coating and preventing metal corrosion. In recent years, researchers have mainly carried out research on the selection of microcapsule core materials, namely self-healing agents, the selection of microcapsule wall materials, and microencapsulation technology. The wall material of the microcapsules has developed from the original single-walled microcapsules to double-walled and multi-walled microcapsules, and its purpose is to solve the problems of poor single-wall mechanical properties, low thermal stability temperature, and poor compactness. At present, the commonly used wall materials mainly include organic wall materials such as urea-formaldehyde resin (PUF), melamine resin (PMF), polysulfone (PSF), polystyrene (PS), polyaniline (PANI), etc., and inorganic wall materials such as dioxide Silicon, etc., double-wall and multi-wall wall materials PSF/SiO2, PS/SiO2, PSF/CNTs, PU/PUF and metal wall materials, etc. Microencapsulation technology is generally determined according to the nature of the wall material, including in-situ polymerization, interfacial polymerization, solvent volatilization, sol-gel, and layer-by-layer self-assembly methods.

[0005] The wall materials in all the self-healing microcapsules described above only play the role of encapsulation protection or slow release of the core material, and the wall materials themselves do not play other positive roles in the corrosion protection of the metal coating.

Summary of the invention

[0006] The object of the present invention is to provide a self-healing microcapsule with conductive polyaniline as the wall material and self-healing agent as the core material.

[0007] The second object of the present invention is to provide a method for preparing self-healing microcapsules with conductive polyaniline as the wall material and self-healing agent as the core material.

[0008] In order to achieve the above objective, the present invention provides the following technical solutions:

[0009] A self-healing microcapsule with conductive polyaniline as the wall material and self-healing agent as the core material.

[0010] Preferably, the self-healing agent is selected from any one or more of reactive self-healing agents, drying oils, and corrosion inhibitors;

[0011] Optionally, the reactive self-healing agent is selected from any one or more of dicyclopentadiene, epoxy resin, isocyanate, and siloxane;

[0012] Optionally, the drying oil is selected from tung oil and/or linseed oil;

[0013] Optionally, the corrosion inhibitor is selected from any one or more of benzothiazole, 8-hydroxyquinoline, and benzotriazole.

[0014] Preferably, the particle size of the microcapsule is 1 micron to 200 microns; preferably, the thickness of the wall material of the microcapsule is 100 nanometers to 20 microns.

[0015] A preparation method of self-repairing microcapsules includes the following steps:

[0016] (1) Prepare a mixed solution A containing an aniline monomer and a first solvent;

[0017] (2) Preparation of mixed solution B containing nano-dispersed particles and mixed solution A;

[0018] (3) Preparation of mixed liquid C containing self-healing agent and mixed liquid B;

[0019] (4) Preparation of mixed solution D containing ammonium persulfate, cobalt sulfate heptahydrate and a second solvent;

[0020] (5) Mix the mixed solution C and the mixed solution D, and stir to react to obtain a self-healing microcapsule in which the wall material is a conductive polyaniline and the core material is a self-healing agent.

[0021] Preferably, the first solvent used for preparing the mixed solution A is an aqueous hydrochloric acid solution, preferably an aqueous hydrochloric acid solution with a concentration of 0.5-1.0 mol/L;

[0022] Preferably, the concentration of the aniline monomer in the first solvent is 0.02-0.2 mol/L;

[0023] Preferably, when preparing the mixed solution A, the mixture of the aniline monomer and the first solvent is ultrasonically dispersed to obtain the mixed solution

A; Further preferably, ultrasonic dispersion is performed at room temperature; more preferably, ultrasonic dispersion is performed for 6-12 hours.

[0024] Preferably, the nano-dispersed particles are selected from any one or more of lignin, modified silica particles, silica dispersions, and graphene oxide;

[0025] Preferably, the nano-dispersed particles are mixed with the mixed solution A in a mass ratio of 0.5-5 wt.%;

[0026] Preferably, when preparing the mixed solution B, the mixture containing the nano-dispersed particles and the mixed solution A is ultrasonically dispersed to obtain the mixed solution B; further preferably, the ultrasonic dispersion is carried out at room temperature; more preferably, the ultrasonic dispersion 5 -20min.

[0027] Preferably, the self-repairing agent is selected from any one or more of reactive self-repairing agents, drying oils, and corrosion inhibitors; optionally, the reactive self-repairing agent is selected from dicyclopentane Any one or more of diene, epoxy resin, isocyanate and siloxane; optionally, the drying oil is selected from tung oil and/or linseed oil; optionally, the corrosion inhibitor is selected from Any one or more of benzothiazole, 8-hydroxyquinoline, and benzotriazole;

[0028] Preferably, the self-healing agent is mixed with the mixture B in a mass ratio of 2-10wt.%;

[0029] Preferably, the mixture containing the self-healing agent and the mixture B is between 0-25. . The lower emulsification is 10-30min, and the emulsification speed is preferably 2000-20000 revolutions per minute, to obtain the mixed liquid C.

[0030] Preferably, the mass ratio of diamond sulfate heptahydrate to ammonium persulfate is (0.5-1): 10;

[0031] The concentration of ammonium persulfate in the second solvent is 0.02-0.2 mol/L; and/or

[0032] The second solvent is an aqueous hydrochloric acid solution, preferably an aqueous hydrochloric acid solution with a concentration of 0.5-1.0 mol/L.

[0033] Preferably, in step (5), the molar ratio of the ammonium persulfate in the mixed solution D to the aniline in the mixed solution C is (0.5-1):1;

[0034] The reaction is between 0-60. . The reaction is preferably carried out for 12-24 hours; and/or

[0035] After the reaction, a suspension is obtained, and the suspension is allowed to stand and then washed, filtered, and dried to obtain the self-repairing microcapsules.

[0036] Application of self-repairing microcapsules in self-repairing metal anticorrosive coatings.

[0037] Benefits

[0038] The above technical solution of the present invention has the following advantages:

[0039] The present invention makes a breakthrough in using conductive polyaniline as the wall material of the self-repairing microcapsule. The self-repairing microcapsule provided combines the anticorrosion effect of conductive polyaniline and the self-repairing effect of the microcapsule. Effectively improve the effective protection of microcapsule-type self-repairing anticorrosive coatings on metal substrates, and broaden the application of microcapsules in the field of self-repairing coatings.

[0040] The present invention also provides a practical method for preparing self-healing microcapsules, which can not only successfully prepare the outer wall composed of conductive polyaniline, but also can be used for various self-healing agents (whether non-oil-soluble It is still oil-soluble) for coating and has a wide range of applications. The preparation method has a simple process, is economical and environmentally friendly, and reduces pollution problems caused by excessive use of surfactants.

Detailed ways

[0041] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0042] In the first aspect, the present invention provides a self-healing microcapsule. In terms of structure, the self-healing microcapsule includes an outer wall and an inner core wrapped by the outer wall. In terms of composition, the self-healing microcapsule is conductively polymerized. Aniline is the wall material (referring to the material of the outer wall), and the self-healing agent is used as the core material (referring to the material of the inner core).

[0043] The conductive polyaniline coated self-healing agent microcapsule provided by the present invention, the wall material of the microcapsule is conductive polyaniline, the core material is a self-healing agent, and the wall material conductive polyaniline has excellent metal anticorrosion performance In addition to protecting the core material with it as the wall material of the microcapsule, the conductive polyaniline will also act synergistically with the self-healing agent to achieve effective corrosion protection of the metal coating.

[0044] The prepared microcapsules have good anticorrosive properties to metals due to the conductive polyaniline wall material, and the microcapsules containing self-healing agents can realize self-repairing of the damage to the metal anticorrosive coating. Therefore, the synthesized microcapsules can be applied to epoxy resin, polytetrafluoroethylene resin and other metal anticorrosive coating resin matrix to prepare self-healing metal anticorrosive coatings, which can be achieved through the synergistic effect of conductive polyaniline and microcapsules Realize the effective protection of the coating on the metal substrate.

[0045] When the wall material is conductive polyaniline, the inventors have concluded through research that the self-healing agent can be selected from any one or more of reactive self-healing agents, drying oils, and corrosion inhibitors, with a wide selection range , Small restrictions, wide sources, cheap and easy to get. Specifically, the reactive self-healing agent may be selected from any one or more of dicyclopentadiene, epoxy resin, isocyanate, and siloxane, and the drying oil is preferably tung oil and/or linseed oil, The corrosion inhibitor may be selected from any one or more of benzothiazole, 8-hydroxyquinoline, and benzotriazole.

[0046] In some preferred embodiments, the particle size of the self-healing microcapsules is in the range of 1 micron to 200 microns. Preferably, the wall material of the microcapsule has a thickness of 100 nanometers to 20 micrometers.

[0047] In the second aspect, the present invention provides a preparation method of self-healing microcapsules, which can not only successfully prepare the outer wall composed of conductive polyaniline, but also can be used for all kinds of self-healing agents (whether non-oil-soluble It is still oil-soluble) for coating, which has a wide range of applications. In addition, the preparation method has a simple process, is economical and environmentally friendly, and reduces pollution problems caused by excessive use of surfactants. Specifically, the preparation method includes the following steps:

[0048] (1) A mixed solution A containing the aniline monomer and the first solvent is prepared. The first solvent may be an aqueous hydrochloric acid solution, preferably with a concentration of 0.5-1.0 mol/L (for example, it may be 0.5 mol/L, 0.6 mol/L, 0.7 mol/L, 0.8 mol/L, 0.9 mol/L, 1.0 mol/L). /L) hydrochloric acid aqueous solution. The concentration of the aniline monomer in the first solvent is preferably 0.02-0.2mol/L, for example, it may be 0.02mol/L, 0.05mol/L, 0.08mol/L, 0.10mol/L, 0.12mol/L, 0.15mol /L, 0.18mol/L, 0.2mol/L. In order to obtain the mixed solution A with uniformly dispersed components, preferably, the mixture of the aniline monomer and the first solvent is ultrasonically dispersed when the mixed solution A is prepared. It is sufficient to perform ultrasonic dispersion at room temperature, and the ultrasonic time can be 6-12 hours.

[0049] (2) Prepare mixed solution B containing nano-dispersed particles and mixed solution A. The nano-dispersed particles are preferably selected from any one or more of lignin, modified silica particles, silica dispersions, and graphene oxide. Preferably, the nano-dispersed particles are mixed with the mixed solution A in a mass ratio of 0.5-5wt.%, that is, the mass of the nano-dispersed particles in the mixed solution A can reach 0.5-5wt.%, for example, it can be 0.5wt. %, 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.%, 3.5wt.%, 4wt.%, 4.5wt.%, 5wt.%. During the research process, the inventor found that the amount of nano-dispersed particles below 0.5wt.% does not have a good dispersion effect on the core material, and it is not possible to prepare microcapsules with better performance. If the amount of nano-dispersed particles exceeds 5wt.%, there will be a large amount of residual nanoparticles in the core material. In solution. In order to obtain a mixed solution B with uniformly dispersed components, preferably, when preparing the mixed solution B, a mixed ultrasonic dispersion containing the nano-dispersed particles and the mixed solution A is prepared. More preferably, ultrasonic dispersion can be performed at room temperature to obtain excellent For dispersion effect, the ultrasonic time can be 5-20min.

[0050] (3) The mixed solution C containing the self-healing agent and the mixed solution B is prepared. The self-repairing agent in the present invention has a wide selection range, and can be selected from any one or more of reactive self-repairing agents, drying oils, and corrosion inhibitors. Specifically, the reactive self-repairing agent can be dicyclopentane Any one or more of diene, epoxy resin, isocyanate, and siloxane, the drying oil may be tung oil and/or linseed oil, and the corrosion inhibitor may be benzothiazole, 8-hydroxyquine Any one or more of morpholine and benzotriazole. Regarding the amount of the self-healing agent, the inventor found that the amount of the self-healing agent affects the wall thickness of the microcapsules, and the wall should not be too thin, otherwise the hardness of the microcapsules is not easy to be damaged, and the wall should not be too thick, otherwise the core material content is too small and the self-repairing effect is poor. After research, the inventors have obtained the optimal dosage as: the self-healing agent is mixed with the mixed solution B according to a mass ratio of 2-10wt.%, that is: the quality of the self-healing agent in the mixed solution B can reach 2-10wt. %, for example, can be 2wt.%, 3wt.%, 4wt.%, 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.%, 10wt.%. In order to obtain an emulsified and evenly divided emulsion C, preferably, the mixture containing the self-healing agent and the mixed liquid B is in the range of 0-25. . The lower emulsification is 10-30min, and the emulsification speed is preferably 2000-20000 rpm.

[0051] (4) Prepare a mixed solution D containing ammonium persulfate, cobalt sulfate heptahydrate and a second solvent. Heptahydrate sulfuric acid is used as a catalyst for the reaction. If the amount is too much, the reaction is too fast, and better performance microcapsules cannot be obtained. If the amount is too small, the reaction is too slow. Preferably, the mass ratio of rhinestone heptahydrate to ammonium persulfate is (0.5-1):10, for example, it can be 0.5:10, 0.6:10, 0.7:10, 0.8:10, 0.9:10, 1:10. The second solvent may be an aqueous hydrochloric acid solution, preferably with a concentration of 0.5-1.0 mol/L (for example, it may be 0.5 mol/L, 0.6 mol/L, 0.7 mol/L, 0.8 mol/L, 0.9 mol/L, 1.0 mol/L). /L) hydrochloric acid aqueous solution. The concentration of ammonium persulfate in the second solvent is preferably 0.02-0.2mol/L, for example, it can be 0.02mol/L, 0.05mol/L, 0.08mol/L, 0.10mol/L, 0.12mol/L, 0.15mol /L, 0.18mol/L, 0.2mol/L.

[0052] (5) Mixing the mixed liquid C and the mixed liquid D, stirring and reacting, to obtain a self-healing microcapsule in which the wall material is a conductive polyaniline and the core material is a self-healing agent. The dosage of the mixed liquid C and the mixed liquid D is preferably determined according to the following standard: the molar ratio of the ammonium persulfate in the mixed liquid D to the aniline in the mixed liquid C is (0.5-1):1. The stirring accompanying the reaction can be a mechanical stirring method or a magnetic stirring method. As for the reaction temperature, the present invention preferably limits it to 0-60C, and the reaction time is preferably 12-24 hours. After the reaction is completed, a suspension is obtained, and the suspension is allowed to stand and then washed, filtered, and dried to obtain the self-repairing microcapsules.

[0053] The self-healing microcapsules provided by the present invention can be used in self-healing metal anti-corrosion coatings, exhibiting excellent corrosion resistance, and are especially suitable for anti-corrosion that requires long life, is difficult to maintain and is in a severely corrosive environment. Coatings (such as the tower body and blades of wind energy generators, offshore drilling platforms, ships, railways, bridges, oil pipelines, and some harsh environments such as special bonding coatings used in aerospace, military and marine applications) can save Cost, reduce environmental pollution, and have great application value.

[0054] The following are examples of the present invention.

Example 1

[0056] A self-repairing microcapsule, in terms of structure, the self-repairing microcapsule includes an outer wall and an inner core wrapped by the outer wall. In terms of composition, the self-repairing microcapsule uses conductive polyaniline as the wall material (referring to the outer wall Material), with self-healing agent as the core material (referring to the material of the inner core), and the self-healing agent is hexamethylene diisocyanate (HDI).

Example 2

[0058] This embodiment provides a preparation method of the self-healing microcapsules in Example 1, which includes the following steps:

[0059] The aniline monomer was added to the 0.5mol/L hydrochloric acid aqueous solution, and the concentration of the aniline in the hydrochloric acid aqueous solution was 0.02mol/

L, ultrasonic dispersion at room temperature for 6 hours to form a mixed solution A.

[0060] The nano-dispersed particles are selected from lignin, the lignin is used as the Pickering emulsion dispersant, and the nano-dispersed particles are added to the mixed solution A according to a mass ratio of 0.5 wt.%, and ultrasonically dispersed for 5 minutes to form a mixed solution B.

[0061] The hexamethylene diisocyanate was added to the mixed solution B in a mass ratio of 2wt.%, and emulsified at a high speed at 25°C

10min, the emulsification speed was 5000 rpm, and the Pickering emulsion C with stable nanoparticles was prepared.

[0062] Ammonium persulfate and ammonium persulfate heptahydrate were added to the 0.5mol/L aqueous hydrochloric acid solution, the concentration of ammonium persulfate in the aqueous hydrochloric acid solution was 0.02mol/L, and the mass ratio of ammonium persulfate and ammonium persulfate was 0.5:10 , After mechanical stirring at room temperature until completely dissolved, a mixed solution D was prepared.

[0063] The mixed solution D is added to the mixed solution C, wherein the molar ratio of ammonium persulfate in solution D to aniline in solution C is 0.5:1,60. . The reaction was carried out under magnetic stirring for 12 hours, the suspension was allowed to stand, and then washed, filtered, and dried to prepare acid-doped conductive polyaniline microcapsules. The self-healing microcapsules have a spherical structure with an average particle size of 10-50 microns.

[0064] By observing the macro morphology of the prepared self-healing microcapsules, it can be seen that the microcapsules are dark green, which is also the main characteristic of conductive polyaniline, which proves that the conductive polyaniline was successfully prepared. Through electrochemical impedance spectroscopy, it is found that the coating with microcapsules has a high impedance modulus in the low frequency region after being immersed in 1wt.% NaCl solution for 1 month after scratching and self-repairing, which proves that the addition of microcapsules effectively improves Anti-corrosion performance of the coating.

Example 3

[0066] A self-repairing microcapsule, in terms of structure, the self-repairing microcapsule includes an outer wall and an inner core wrapped by the outer wall. In terms of composition, the self-repairing microcapsule uses conductive polyaniline as the wall material (referring to the outer wall Material), the self-healing agent is used as the core material (refers to the material of the inner core), and the self-healing agent is benzothiazole.

Example 4

[0068] This embodiment provides a preparation method of the self-healing microcapsules in Example 3, which includes the following steps:

[0069] The aniline monomer was added to the 0.8mol/L hydrochloric acid aqueous solution, the concentration of the aniline in the hydrochloric acid aqueous solution was 0.1mol/L, and the mixed solution A was formed by ultrasonic dispersion at room temperature for 10 hours.

[0070] Graphene oxide is selected for the nano-dispersed particles, and graphene oxide is used as the Pickering emulsion dispersant. The nano-dispersed particles are added to the mixed solution A according to a mass ratio of 2.5 wt.%, and ultrasonically dispersed for 12 minutes to form a mixed solution B.

[0071] The benzothiazole was added to the mixed solution B in a mass ratio of 6 wt.%, and the mixture was emulsified at a high speed at 15° C. for 20 min and the emulsification speed was 10,000 revolutions per minute to prepare a Pickering emulsion C with stable nanoparticles.

[0072] Ammonium persulfate and ammonium persulfate heptahydrate were added to the 0.8mol/L aqueous hydrochloric acid solution, the concentration of ammonium persulfate in the aqueous hydrochloric acid solution was 0.1 mol/L, and the mass ratio of ammonium persulfate and ammonium persulfate was 0.8:10 , A mixed solution D was prepared after mechanical stirring at room temperature until it was completely dissolved.

[0073] The mixed solution D is added to the mixed solution C, wherein the molar ratio of ammonium persulfate in solution D to aniline in solution C is 0.8:1,20. . The reaction was carried out under magnetic stirring for 20 hours, the suspension was allowed to stand, and then washed, filtered and dried to prepare acid-doped conductive polyaniline microcapsules. The microcapsule was dark green, which proved that the conductive polyaniline was successfully prepared. Through electrochemical impedance spectroscopy, it is found that the coating with microcapsules has a high impedance modulus in the low frequency area after being immersed in 1wt.% NaCl solution for 1 month after scratching and self-repairing, which proves that the addition of microcapsules effectively improves Anti-corrosion performance of the coating.

Embodiment 5

[0075] A self-repairing microcapsule, in terms of structure, the self-repairing microcapsule includes an outer wall and an inner core wrapped by the outer wall. In terms of composition, the self-repairing microcapsule uses conductive polyaniline as the wall material (referring to the outer wall Material), with self-healing agent as the core material (referring to the material of the inner core), and tung oil as the self-healing agent.

Embodiment 6

[0077] This embodiment provides a preparation method of the self-healing microcapsules in embodiment 5, which includes the following steps:

[0078] The aniline monomer was added to the 1.0 mol/L hydrochloric acid aqueous solution, the concentration of the aniline in the hydrochloric acid aqueous solution was 0.2 mol/L, and the mixed solution A was formed by ultrasonic dispersion at room temperature for 12 hours.

[0079] The nano-dispersed particles are selected from lignin, the lignin is used as the Pickering emulsion dispersant, and the nano-dispersed particles are added to the mixed solution A according to a mass ratio of 5 wt.%, and ultrasonically dispersed for 20 minutes to form a mixed solution B.

[0080] The tung oil was added to the mixed solution B at a mass ratio of 10wt.%, 0. Under high-speed emulsification for 20 minutes, the emulsification speed was 5000 rpm, and the Pickering emulsion C with stable nanoparticles was prepared.

[0081] Ammonium persulfate and ammonium persulfate heptahydrate were added to the 1.0 mol/L aqueous hydrochloric acid solution, the concentration of ammonium persulfate in the aqueous hydrochloric acid solution was 0.2 mol/L, and the mass ratio of ammonium persulfate and ammonium persulfate was 1:10 , A mixed solution D was prepared after mechanical stirring at room temperature until it was completely dissolved.

[0082] The mixed solution D is added to the mixed solution C, wherein the molar ratio of ammonium persulfate in solution D to aniline in solution C is 1:1,0. Under magnetic stirring for 24 hours, the suspension was allowed to stand, and then washed, filtered and dried to prepare acid-doped conductive polyaniline microcapsules. The microcapsule was dark green, which proved that the conductive polyaniline was successfully prepared. Through electrochemical impedance spectroscopy, it was found that the coating with microcapsules was scratched and self-repaired after being immersed in 1wt.%NaCl solution for 1 month. The low-frequency region still had a higher impedance modulus, which proved that the addition of microcapsules effectively improved Anti-corrosion performance of the coating.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: It is still possible to modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention

Spirit and scope.