An impact-resistant coating and method of making the same

Abstract

The present application belongs to the technical field of impact-resistant coating, and specifically discloses an impact-resistant toughness coating and a preparation method thereof, which comprises the following steps: adding a base resin and a nano filler dispersion liquid into a core-shell structure rubber particle emulsion, adding a curing agent and a diluent, and stirring uniformly to obtain a coating slurry; and coating the slurry on the surface of a metal substrate to obtain the coating; the core-shell structure rubber particle has a polybutadiene core layer and a methyl methacrylate and acrylic acid mixture shell layer; and the nano composite filler is a mixture of modified nano clay and modified graphene nanosheet at a mass ratio of 1:0.5-2. The core-shell structure rubber particle is uniformly dispersed in the coating, and when impacted, the elastic deformation of the rubber particle can efficiently dissipate energy, so that the coating can stably achieve the performance requirement of impact resistance of greater than or equal to 30 cm; meanwhile, the nano filler added in the coating has a blocking and bridging effect, effectively delays crack propagation, greatly reduces the risk of failure due to crack penetration, and enhances the durability and reliability of the coating.

Description

Technical Field

[0001] This invention belongs to the field of impact-resistant coating technology, specifically relating to an impact-resistant toughness coating and its preparation method. Background Technology

[0002] Corrosion is a common natural phenomenon, mainly caused by the chemical reaction between metallic materials and corrosive media in their environment, resulting in changes such as deterioration and dissolution. Metal components, especially in marine environments, are highly susceptible to damage and deterioration, necessitating protective measures. Organic composite coatings are widely used due to their advantages of durability, high toughness, ease of manufacturing, and cost-effectiveness. Epoxy resin is the most widely used, finding extensive applications in aerospace, electronic packaging, and automotive manufacturing due to its excellent mechanical properties, chemical corrosion resistance, and adhesion. However, pure epoxy resin coatings have limited toughening effects. Researchers have attempted to toughen these coatings by mixing functional fillers with specific mechanical properties, such as microspheres and rubber particles. However, traditional microspheres and rubber particles suffer from poor interfacial compatibility, making uniform dispersion in the epoxy matrix difficult and often leading to agglomeration. Furthermore, the toughening mechanism primarily relies on physical encapsulation, failing to form effective chemical bonds, resulting in limited improvement in impact strength (typically only 20%–30%), which is insufficient to meet the impact strength requirements of high-end applications.

[0003] In existing technologies, when using core-shell structured rubber particles as toughening agents, the lack of sufficient differentiated innovation in core-shell structure, raw material selection, and preparation processes makes it difficult to surpass current toughening levels. Furthermore, in practices involving the addition of nano-clay and carbon nanotubes to improve material impact resistance and other properties, the common technical effects are merely simple additives, failing to achieve synergistic results exceeding conventional expectations in this field. Moreover, conventional preparation processes, when handling such material systems, are prone to encountering complex interactions between components, which can hinder the full realization of the final technical efficacy.

[0004] This invention aims to overcome these technical challenges and develop an energy dissipation enhancement technology for impact-resistant and tough coatings, endowing the coating with excellent impact resistance and efficient energy dissipation capabilities, while achieving significant improvements in technological innovation and providing groundbreaking solutions for related fields. Summary of the Invention

[0005] This invention aims to overcome the technical problem of improving the impact resistance of existing coatings and develop an impact-resistant and tough coating. It uses uniquely designed core-shell structured rubber particles as toughening agents and adds nanocomposite fillers. These particles work synergistically with the coating matrix and interface modifiers to accelerate the curing reaction, enhance the interfacial bonding force, increase the impact strength by 30%-50%, and extend the impact resistance of the coating to ≥30cm, thus extending the impact life by 2-3 times.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An impact-resistant and toughening coating comprises the following materials in parts by weight: 80-100 parts matrix resin, 15-20 parts toughening agent, and 5-10 parts nanocomposite filler; the toughening agent is a core-shell rubber particle emulsion, the core layer of which is polybutadiene, and the shell layer is a mixture of methyl methacrylate and acrylic acid; the shell layer thickness is 50-100 nm; the nanocomposite filler is a mixture of modified nanoclay and modified graphene nanosheets at a mass ratio of 1:0.5-2.

[0008] The working principle of the impact-resistant toughness coating of this invention is as follows: Precisely designed core-shell structured rubber particles are uniformly dispersed in the coating. Upon impact, the elastic deformation of the core rubber particles efficiently dissipates energy, enabling the coating to stably achieve the performance requirement of impact resistance ≥30cm. Simultaneously, nanocomposite fillers are added, with modified nanoclay and modified graphene nanosheets uniformly distributed in the coating. The blocking effect of the modified nanoclay sheets and the bridging effect of the modified graphene nanosheets work synergistically to effectively delay crack propagation, significantly reducing the risk of coating failure due to crack penetration and enhancing the coating's durability and reliability. Through optimization of the coating formulation, the relationship between the coating's impact strength and storage modulus is satisfied (G'' / G'>0.3), ensuring the formation of a reasonable cross-linked network structure, greatly enhancing the coating's energy dissipation capacity, and providing a crucial guarantee for achieving high impact resistance (≥30cm).

[0009] Preferably, the matrix resin is epoxy resin, and more preferably epoxy resin E-51.

[0010] Preferably, the polybutadiene has a molecular weight of 80,000-100,000 and a molecular weight distribution index of 1.8-2.2.

[0011] Preferably, the mass ratio of methyl methacrylate to acrylic acid is 8-10:1, more preferably 9:1.

[0012] Preferably, the modified nanoclay is modified using a quaternary ammonium salt surfactant. The specific method includes: adding nanoclay to deionized water to prepare a nanoclay suspension with a mass fraction of 5%-10%, and stirring at 300-500 r / min for 10-15 min at room temperature to ensure uniform dispersion of the nanoclay. Then, adding 10%-15% of the quaternary ammonium salt surfactant by mass of the nanoclay, and continuously stirring at 400-600 r / min for 2-3 h at 50-60°C. After stirring, the mixture is filtered, and the filter cake is washed multiple times with deionized water until the washing liquid is neutral. Finally, the washed filter cake is dried in a vacuum drying oven at 80-100°C for 8-12 h to obtain the modified nanoclay.

[0013] Preferably, the quaternary ammonium salt surfactant includes any one of dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

[0014] Preferably, the modified graphene nanosheets are modified using a chemical reduction oxidation method, specifically including:

[0015] 325 mesh natural graphite powder and concentrated sulfuric acid were mixed at a mass ratio of 1:23 and placed in an ice-water bath. Potassium permanganate was slowly added while stirring. The mass ratio of graphite powder to potassium permanganate was 1:6. The mixture was stirred and reacted for 2 hours. Then the temperature was raised to 35°C and the mixture was stirred and reacted for another 12 hours.

[0016] Add deionized water to the above reaction to raise the system temperature to 98°C, react for 30 min, then add 30% hydrogen peroxide solution until the solution turns bright yellow to obtain graphene oxide dispersion.

[0017] The pH of the graphene oxide dispersion was adjusted to 8-9, and hydrazine hydrate (80% by weight of graphene oxide) was added. The mixture was refluxed at 95°C for 24 hours. After the reaction was completed, the mixture was centrifuged, washed repeatedly with deionized water and ethanol, and dried in a vacuum drying oven at 60°C for 12 hours to obtain modified graphene nanosheets.

[0018] Preferably, the modified graphene nanosheets have a diameter of 5-10 μm and a thickness of 1-5 nm.

[0019] Preferably, the core-shell rubber particle emulsion is prepared by the following method:

[0020] 1) Dissolve the emulsifier in deionized water according to the weight parts and stir until completely dissolved to form an emulsion;

[0021] 2) Add polybutadiene to the above emulsion according to the weight parts, stir and react at 70-80℃ for 15-20 min to form a pre-emulsion; slowly drop the initiator solution into the pre-emulsion to initiate the polymerization reaction;

[0022] 3) Add a mixture of methyl methacrylate and acrylic acid to the system in step 2) at a dropping rate of 0.5-1.0 g / min. After the addition is complete, continue the reaction for 4-6 hours, cool to room temperature and dry to obtain a core-shell rubber particle emulsion.

[0023] Preferably, the initiator is ammonium persulfate and the emulsifier is sodium dodecylbenzenesulfonate.

[0024] Another object of the present invention is to provide a method for preparing an impact-resistant and tough coating, the steps of which include:

[0025] (1) Add the matrix resin to the core-shell rubber particle emulsion according to the weight parts and stir at high speed for 30-40 min;

[0026] (2) Mix the modified nano-clay and modified graphene nanosheets in proportion, and ultrasonically disperse for 30-40 min to prepare a dispersion with a concentration of 10-15%; add the dispersion to step (1) and continue ultrasonic dispersion for 20-30 min.

[0027] (3) Add curing agent and diluent to step (2) in proportion, and stir evenly to obtain coating slurry;

[0028] (4) Apply the coating slurry to the surface of the metal substrate by spraying, control the coating thickness to 80μm, and cure at 75-90℃ for 2-3h to obtain an impact-resistant and tough coating.

[0029] Preferably, the curing agent is polyamide 650.

[0030] Preferably, the diluent is n-butanol.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. This invention develops a toughening coating with an impact resistance of ≥30cm. It utilizes core-shell structured rubber particles composed of polybutadiene-g-acrylate as a toughening agent. Due to the low glass transition temperature of the core polybutadiene and the good compatibility and functional group reactivity of the shell acrylate polymer with the matrix, the core-shell structured rubber particles can effectively disperse stress and absorb impact energy upon impact, significantly improving the material's impact resistance. Simultaneously, the shell functional groups synergistically interact with the coating matrix and interface modifier, accelerating the curing reaction rate, enhancing interfacial bonding, and further improving the overall material performance. Compared to traditional core-shell structured rubber particle toughening systems, the impact strength is increased by 30%-50%.

[0033] 2. In this invention, polybutadiene with specific molecular weight distribution and functional group characteristics is selected as the core layer material for the core-shell rubber particles. Its glass transition temperature is below -50°C, ensuring that it can maintain good flexibility in low-temperature environments. The shell layer is made of acrylate polymers. Through specific initiators and polymerization processes, the shell layer thickness is controlled between 50-100 nm. In addition, an appropriate amount of functional groups that can chemically react with the coating matrix, such as carboxyl groups and hydroxyl groups, are grafted onto the shell layer surface to enhance compatibility and interaction with the matrix.

[0034] 3. The core-shell rubber particle preparation process of this invention adopts emulsion polymerization, strictly controls the reaction temperature between 70 and 80°C, the reaction time is 4 to 6 hours, and the monomer dropping rate is 0.5 to 1.0 g / min, so as to precisely control the formation of the core-shell structure and solve the technical problem that the toughening effect of the existing core-shell structure is not ideal.

[0035] 4. In this invention, the addition of surface-treated nano-clay and graphene nanosheets enhances the interaction between the abundant functional groups on their surfaces and the coating matrix. During crack propagation, the nano-clay layers can block crack propagation layer by layer, while the graphene nanosheets can effectively bridge cracks and prevent further crack propagation. This not only significantly improves the impact resistance of the coating but also brings technical benefits such as improved electrical conductivity and thermal stability, achieving a synergistic effect and extending the impact resistance life of the coating by 2-3 times.

[0036] 5. By optimizing the coating formulation and adjusting the curing temperature, time, and proportion of each component in the coating formulation, this invention ensures that the relationship between the coating impact strength and storage modulus meets the condition (G'' / G'>0.3), forming a reasonable cross-linked network structure. This greatly enhances the energy dissipation capacity of the coating and provides an important guarantee for achieving high impact resistance (≥30cm). Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a SEM image of the impact-resistant toughness coating surface prepared in Example 4 of the present invention;

[0039] Figure 2 This is a BSE diagram of the cross-section of the impact-resistant and tough coating sample prepared in Example 4 of the present invention. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. Example 1

[0041] An impact-resistant and tough coating comprises the following materials in parts by weight: 80 parts epoxy resin E-51, 15 parts core-shell rubber particle emulsion with a shell thickness of 50 nm, and 5 parts nanocomposite filler; wherein the nanocomposite filler is a mixture of modified nanoclay and modified graphene nanosheets at a mass ratio of 1:0.5.

[0042] A method for preparing an impact-resistant and toughening coating, comprising the following steps:

[0043] Preparation of core-shell rubber particle emulsion:

[0044] 1) Dissolve 3 parts by weight of sodium dodecylbenzenesulfonate in 200 parts by weight of deionized water and stir until completely dissolved to form an emulsion;

[0045] 2) Add 50 parts by weight of polybutadiene monomer with a molecular weight of 80,000-100,000 and a molecular weight distribution index of 1.8-2.2 to the above emulsion, and stir at 70°C for 20 min to form a pre-emulsion; slowly add ammonium persulfate solution (2 parts by weight of ammonium persulfate dissolved in 20 parts by weight of deionized water) dropwise into the pre-emulsion to initiate the polymerization reaction;

[0046] 3) Add a mixture of methyl methacrylate and acrylic acid in a mass ratio of 9:1 to the system in step 2) at a dropping rate of 0.5 g / min. After the addition is complete, continue the reaction for 6 h, cool to room temperature and dry to obtain a core-shell rubber particle emulsion with a core-shell thickness of 50 nm.

[0047] (2) Preparation of nanocomposite filler: Modified nanoclay and modified graphene nanosheets were mixed at a mass ratio of 1:0.5 and ultrasonically dispersed for 30 min to prepare a dispersion with a concentration of 10%.

[0048] (3) Preparation of coating slurry: 80 parts by weight of epoxy resin E-51 were added to 15 parts by weight of core-shell rubber particle emulsion and stirred at 3000 r / min for 30 min; then the dispersion from step (2) was added and ultrasonically dispersed at 300 W for 30 min; 40 parts by weight of polyamide 650 and 10 parts by weight of n-butanol were added and stirred evenly to obtain coating slurry;

[0049] (4) Coating preparation: The coating slurry is applied to the surface of the metal substrate by spraying, the coating thickness is controlled to be 80μm, and cured at 75℃ for 3h to obtain an impact toughness coating. Example 2

[0050] An impact-resistant and tough coating comprises the following materials in parts by weight: 90 parts epoxy resin E-51, 18 parts core-shell rubber particle emulsion with a shell thickness of 90 nm, and 8 parts nanocomposite filler; wherein the nanocomposite filler is a mixture of modified nanoclay and modified graphene nanosheets in a mass ratio of 1:1.

[0051] A method for preparing an impact-resistant and toughening coating, comprising the following steps:

[0052] (1) Preparation of core-shell rubber particle emulsion:

[0053] 1) Dissolve 3 parts by weight of sodium dodecylbenzenesulfonate in 200 parts by weight of deionized water and stir until completely dissolved to form an emulsion;

[0054] 2) Add 50 parts by weight of polybutadiene monomer to the above emulsion and stir at 75°C for 18 min to form a pre-emulsion; slowly add ammonium persulfate solution (2 parts by weight of ammonium persulfate dissolved in 20 parts by weight of deionized water) dropwise into the pre-emulsion to initiate the polymerization reaction;

[0055] 3) Add a mixture of methyl methacrylate and acrylic acid to the system in step 2) at a dropping rate of 0.8 g / min. After the addition is complete, continue the reaction for 5 h, cool to room temperature and dry to obtain a core-shell rubber particle emulsion with a core-shell thickness of 90 nm.

[0056] (2) Preparation of nanocomposite filler: Modified nanoclay and modified graphene nanosheets were mixed at a mass ratio of 1:1 and ultrasonically dispersed for 35 min to prepare a dispersion with a concentration of 15%.

[0057] (3) Preparation of coating slurry: Epoxy resin E-51 was added to the core-shell rubber particle emulsion by weight and stirred at 3000 r / min for 35 min; then the dispersion of step (2) was added and ultrasonically dispersed at 300 W for 25 min; 40 parts by weight of polyamide 650 and 10 parts by weight of n-butanol were added and stirred evenly to obtain coating slurry;

[0058] (4) Coating preparation: The coating slurry is applied to the surface of the metal substrate by spraying, the coating thickness is controlled to be 80 μm, and cured at 80℃ for 2.5 h to obtain an impact toughness coating. Example 3

[0059] An impact-resistant and tough coating comprises the following materials in parts by weight: 100 parts epoxy resin E-51, 20 parts core-shell rubber particle emulsion with a shell thickness of 100 nm, and 10 parts nanocomposite filler; wherein the nanocomposite filler is a mixture of modified nanoclay and modified graphene nanosheets in a mass ratio of 1:2.

[0060] A method for preparing an impact-resistant and toughening coating, comprising the following steps:

[0061] (1) Preparation of core-shell rubber particle emulsion:

[0062] 1) Dissolve 3 parts by weight of sodium dodecylbenzenesulfonate in 200 parts by weight of deionized water and stir until completely dissolved to form an emulsion;

[0063] 2) Add 50 parts by weight of polybutadiene monomer to the above emulsion and stir at 80°C for 15 min to form a pre-emulsion; slowly add ammonium persulfate solution (2 parts by weight of ammonium persulfate dissolved in 20 parts by weight of deionized water) dropwise into the pre-emulsion to initiate the polymerization reaction;

[0064] 3) Add a mixture of methyl methacrylate and acrylic acid to the system in step 2) at a dropping rate of 1.0 g / min. After the addition is complete, continue the reaction for 4 h, cool to room temperature and dry to obtain a core-shell rubber particle emulsion with a core-shell thickness of 100 nm.

[0065] (2) Preparation of nanocomposite filler: Modified nanoclay and modified graphene nanosheets were mixed at a mass ratio of 1:2 and ultrasonically dispersed for 40 min to prepare a dispersion with a concentration of 15%.

[0066] (3) Preparation of coating slurry: Epoxy resin E-51 was added to the core-shell rubber particle emulsion by weight and stirred at 3000 r / min for 40 min; then the dispersion of step (2) was added and ultrasonically dispersed at 300 W for 20 min; 40 parts by weight of polyamide 650 and 10 parts by weight of n-butanol were added and stirred evenly to obtain coating slurry;

[0067] (4) Coating preparation: The coating slurry is applied to the surface of the metal substrate by spraying, the coating thickness is controlled to be 80 μm, and cured at 90℃ for 2 h to obtain an impact toughness coating. Example 4

[0068] An impact-resistant and tough coating comprises the following materials in parts by weight: 100 parts epoxy resin E-51, 20 parts core-shell rubber particle emulsion with a shell thickness of 75 nm, and 10 parts nanocomposite filler; wherein the nanocomposite filler is a mixture of modified nanoclay and modified graphene nanosheets in a mass ratio of 1:1.

[0069] A method for preparing an impact-resistant and toughening coating, comprising the following steps:

[0070] (1) Preparation of core-shell rubber particle emulsion:

[0071] 1) Dissolve 3 parts by weight of sodium dodecylbenzenesulfonate in 200 parts by weight of deionized water and stir until completely dissolved to form an emulsion;

[0072] 2) Add 50 parts by weight of polybutadiene monomer to the above emulsion and stir at 75°C for 15 min to form a pre-emulsion; slowly add ammonium persulfate solution (2 parts by weight of ammonium persulfate dissolved in 20 parts by weight of deionized water) dropwise into the pre-emulsion to initiate the polymerization reaction;

[0073] 3) Add a mixture of methyl methacrylate and acrylic acid in a mass ratio of 9:1 to the system in step 2) at a dropping rate of 0.8 g / min. After the addition is complete, continue the reaction for 5 h, cool to room temperature and dry to obtain a core-shell rubber particle emulsion with a core-shell thickness of 75 nm.

[0074] (2) Preparation of nanocomposite filler: Modified nanoclay and modified graphene nanosheets were mixed at a mass ratio of 1:1 and ultrasonically dispersed for 30 min to prepare a dispersion with a concentration of 15%.

[0075] (3) Preparation of coating slurry: Epoxy resin E-51 is added to the core-shell rubber particle emulsion by weight and stirred at high speed at 3000 r / min for 30 min; then the dispersion in step (2) is added and ultrasonically dispersed at 300 W power for 20 min; 40 parts by weight of polyamide 650 and 10 parts by weight of n-butanol are added and stirred evenly to obtain coating slurry;

[0076] (4) Coating preparation: The coating slurry is applied to the surface of the metal substrate by spraying, the coating thickness is controlled to be 80 μm, and cured at 80℃ for 2 h to obtain an impact toughness coating.

[0077] Comparative Example 1

[0078] Compared with Example 4, the core-shell rubber particles were replaced with shell-less polybutadiene rubber particles, and the preparation method of the core-shell rubber particle emulsion in step (1) was omitted. The remaining raw materials and steps were the same as in Example 4.

[0079] Comparative Example 2

[0080] Compared with Example 4, the core-shell rubber particles were replaced with commercially available copolymethyl acrylate-butadiene (MBS) core-shell particles, with the product model being PARALOID EXL-2690; the preparation method of the core-shell rubber particle emulsion in step (1) was omitted, and the remaining raw materials and steps were the same as in Example 4.

[0081] Comparative Example 3

[0082] Compared with Example 4, the core-shell rubber particles were replaced with commercially available copolymethyl acrylate-butadiene (MBS) core-shell particles, product model PARALOID EXL-2690, the nanocomposite filler was removed, and the preparation method of the core-shell rubber particle emulsion in step (1) was omitted. The remaining raw materials and steps were the same as in Example 4.

[0083] Comparative Example 4

[0084] Compared with Example 4, the nanocomposite filler was removed, while the other raw materials and steps were the same as in Example 4.

[0085] Comparative Example 5

[0086] Compared with Example 4, the modified nano-clay was removed, and only modified graphene nanosheets were added as nanofillers. The other raw materials and steps were the same as in Example 4.

[0087] Comparative Example 6

[0088] Compared with Example 4, the modified graphene nanosheets were removed, and only modified nanoclay was added as a nanofiller. The other raw materials and steps were the same as in Example 4.

[0089] Comparative Example 7

[0090] Compared with Example 4, ordinary clay and graphene sheets were added as nanofillers, while the other raw materials and steps were the same as in Example 4.

[0091] Comparative Example 8

[0092] Compared to Example 4, the core-shell rubber particles were replaced with commercially available copolymethyl acrylate-butadiene (MBS) core-shell particles, product model PARALOID EXL-2690; the modified nanoclay and modified graphene nanosheets were replaced with ordinary clay and graphene sheets, and the remaining raw materials and steps were the same as in Example 4.

[0093] Test case

[0094] The impact resistance and surface characterization of the coated samples prepared above were performed using the following specific test methods:

[0095] (1) Impact resistance

[0096] Test conditions: According to GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film", the drop weight is 1kg and the impact height is set to 35cm.

[0097] Test data characterization: Record whether the coating cracks or peels under the impact conditions to determine whether it meets the requirement of impact resistance ≥30cm.

[0098] (2) Dynamic mechanical properties

[0099] Significance of the test: Dynamic mechanical properties are mainly used to characterize the viscoelastic behavior of materials under alternating stress. Among them, the storage modulus G' reflects the material's ability to store energy during elastic deformation, the loss modulus G'' reflects the material's ability to lose energy during viscous deformation, and G'' / G' can reflect the relative degree of viscoelasticity of the material.

[0100] Test conditions: Dynamic mechanical analyzer (DMA) was used, the test temperature was 25 ℃, and the frequency was 1 Hz.

[0101] Test data characterization: Record the specific values ​​of energy storage modulus G', loss modulus G'', and G'' / G'.

[0102] (3) Impact resistance life

[0103] Test conditions: Cyclic impact test was conducted with an impact height of 30cm. The coating condition was observed after each impact.

[0104] Test data characterization: Record the number of impacts the coating undergoes under cyclic impacts while maintaining a good condition without cracks or peeling.

[0105] Characterization

[0106] The impact-resistant toughness coating prepared in Example 4 was subjected to SEM testing, and the cross-section of the coating sample was characterized by BSE. Figure 1 SEM, Figure 2 As can be seen from BSE, the core-shell structured rubber particles prepared by this invention are uniformly distributed in the coating to form a dense layer. When subjected to impact, the high elasticity of the core layer rubber can effectively dissipate energy, and the uniform dispersion avoids the problems of agglomeration and excessive deformation, thus effectively improving the impact resistance of the coating.

[0107] The performance characterization test results are shown in Table 1. As can be seen from the data in Table 1, the coatings prepared in Examples 1-4 of this invention showed no cracks or peeling under an impact height of 30 cm, while the coatings prepared in Comparative Examples 1-8 all showed varying degrees of cracking and peeling. Furthermore, the coating prepared in this invention can withstand an impact height of 35 cm, and its impact resistance is far superior to that of traditional coatings and the coatings involved in the comparative examples. Further characterization of the coating surface after impact shows that the internal cracks in the coating of this invention are bridged by the added nanofiller—modified nanoclay and modified graphene nanosheets—effectively preventing crack propagation and preventing penetrating damage.

[0108] The test data from Comparative Examples 4-7 also show that without the addition of nanofillers, or with only traditional fillers, or with only one type of filler, the impact resistance, dynamic matching, and impact life are far lower than those of Example 4 of this invention due to the loss of the crack bridging effect of nanofillers. This proves that the core-shell structured rubber particles and nanofillers in the coating of this invention have a synergistic effect, which can effectively delay crack propagation, greatly reduce the risk of coating failure due to crack penetration, and enhance the durability and reliability of the coating. As can be seen from the cyclic impact data in Table 1, the impact life of the coating prepared by this invention is significantly improved, with microcracks appearing only after more than 50 impacts.

[0109] The test data from Comparative Examples 1-3 and Comparative Example 8 show that traditional single rubber particles have poor compatibility with the matrix and low impact energy dissipation efficiency due to the lack of core-shell structure design. Existing core-shell particles also have weak interfacial bonding with the matrix due to the lack of shell functional groups and the deviation of preparation process parameters from the scope of this invention. As a result, their performance is also lower than that of the core-shell structured rubber particle emulsion independently developed in this invention.

[0110] As can be seen from the data of Comparative Examples 7 and 8, the unmodified nano-clay and graphene sheets have poor dispersibility and weak interaction with the matrix, which prevents them from fully exerting the crack bridging effect. As a result, although their performance is better than that of Comparative Example 1, it is still significantly lower than that of Example 4. This proves the importance of the precise design of the core-shell structure and the synergistic effect of the nanofillers in this invention.

[0111] Table 1 Performance test data of different coatings

[0112]

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. An impact toughness coating characterized by, The method comprises the following materials by weight: 80-100 parts of base resin, 15-20 parts of toughening agent, 5-10 parts of nano composite filler; the toughening agent is core-shell rubber particle emulsion, the core layer of which is polybutadiene with a molecular weight of 80000-100000 and a molecular weight distribution index of 1.8-2.2; the shell layer is a mixture of methyl methacrylate and acrylic acid with a mass ratio of 8-10:1; the nano composite filler is mixed by modified nano clay and modified graphene nanosheet with a mass ratio of 1:0.5-2, the modified nano clay is modified by using quaternary ammonium salt surfactant; the modified graphene nanosheet is modified by using chemical reduction oxidation method; wherein the core-shell rubber particle emulsion is prepared by the following method: 1) Dissolve the emulsifier in deionized water by weight parts and stir until completely dissolved to form an emulsion; 2) Add polybutadiene to the above emulsion by weight parts, and stir at 70-80℃ for 15-20min to form a pre-emulsion; slowly drop the initiator solution into the pre-emulsion to initiate polymerization; 3) Add the mixture of methyl methacrylate and acrylic acid to the system of step 2) at a drop rate of 0.5-1.0g / min, continue to react for 4-6h after the drop is completed, and cool to room temperature to dry to obtain the core-shell rubber particle emulsion.

2. The impact toughness coating of claim 1, wherein, The modified graphene nanosheet has a sheet diameter of 5-10μm and a thickness of 1-5nm.

3. The impact toughness coating of claim 1, wherein, The initiator is ammonium persulfate, and the emulsifier is sodium dodecyl benzene sulfonate.

4. A process for the production of an impact toughness coating according to any one of claims 1 to 3, characterized in that The steps include: (1) Add the base resin to the core-shell rubber particle emulsion by weight parts, and stir at high speed for 30-40min; (2) Mix the modified nano clay and modified graphene nanosheet by proportion, ultrasonic dispersion for 30-40min, and configure a dispersion liquid with a concentration of 10-15%; add the dispersion liquid to step (1) and continue to ultrasonic dispersion for 20-30min; (3) Add the curing agent and diluent to step (2) by proportion, stir uniformly to obtain a coating slurry; (4) Apply the coating slurry to the surface of the metal substrate by spraying process, control the coating thickness to be 80μm, and cure at 75-90℃ for 2-3h to obtain an impact toughness coating.

5. The method of preparing an impact toughness coating according to claim 4, characterized in that, The shell layer in the core-shell structure has a thickness of 50-100nm.

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