Corrosion-resistant coating material and preparation method thereof

Abstract

The invention relates to the technical field of coatings, in particular to a corrosion-resistant coating material and a preparation method thereof. The corrosion-resistant coating material comprises the following components in parts by mass: 80-100 parts of epoxy resin, 5-20 parts of a modified phenolic aldehyde amine curing agent, 2-5 parts of a waterproof agent, 5-10 parts of a corrosion inhibitor and 40-55 parts of a lubricant. The modified phenolic aldehyde amine curing agent is obtained by carrying out Mannich reaction on phenol, thymol, aliphatic polyamine and formaldehyde. The phenol provides a rigid benzene ring structure, and endows a cured product with good heat resistance and chemical resistance. Thymol improves the flexibility and adhesive force of the cured product and enhances the hydrophobicity of the cured product at the same time. The epoxy resin and the modified phenolic aldehyde amine curing agent are polymerized, the waterproof agent, the corrosion inhibitor and the lubricant are wrapped, and the obtained coating material has good adhesive force and corrosion resistance.

Description

Technical Field

[0001] This application relates to the field of coating technology, and in particular to a corrosion-resistant coating material and its preparation method. Background Technology

[0002] Currently, metal materials are commonly used in the processing of medical devices. However, metal materials have poor corrosion resistance, and medical metal materials, after long-term implantation in the human body, are susceptible to uniform corrosion due to the complex chemical and physical effects of the body fluid environment. This not only leads to a decline or failure of the mechanical properties of the metal materials but may also leach toxic metal ions, triggering inflammatory and immune responses, and reducing the product's lifespan, thus having certain limitations. While some coating materials have achieved some success in improving the corrosion resistance of medical devices, there is still room for improvement in corrosion resistance, and further improvements in adhesion are needed to better protect the metal materials. Summary of the Invention

[0003] In view of the above, this application provides a corrosion-resistant coating material and its preparation method, which has high corrosion resistance and adhesion.

[0004] In the first aspect, this application proposes a corrosion-resistant coating material and adopts the following technical solution.

[0005] A corrosion-resistant coating material, by weight, comprises the following components: 80-100 parts epoxy resin, 5-20 parts modified phenolic amine curing agent, 2-5 parts waterproofing agent, 5-10 parts corrosion inhibitor, and 40-55 parts lubricant.

[0006] The modified phenolic amine curing agent is obtained by the Mannich reaction of phenol, thymol, aliphatic polyamine and formaldehyde.

[0007] By employing the above technical solution, phenol provides a rigid benzene ring structure, which is the basis for forming the phenolic resin skeleton and endows the cured product with good heat resistance and chemical resistance. Thymol improves the flexibility and adhesion of the cured product while enhancing its hydrophobicity. Aliphatic polyamines provide amine groups, which are both raw materials for the Mannich reaction and active groups in the final product capable of curing with epoxy resin. Formaldehyde, as a bridging component, connects phenol / thymol and amines in the Mannich reaction. The resulting modified phenolic amine curing agent is a viscous liquid containing multiple amine groups and phenolic nuclei. It retains the characteristic of amine curing agents that can react with epoxy resin at room temperature, and the introduction of phenolic nuclei and thymol branches endows the cured coating with better adhesion, toughness, and corrosion resistance. The polymerization of epoxy resin with the modified phenolic amine curing agent, encapsulating waterproofing agents, corrosion inhibitors, and lubricants, results in a coating material with good adhesion and corrosion resistance.

[0008] A preferred embodiment of the corrosion-resistant coating material is that the mass ratio of phenol, thymol, aliphatic polyamine and formaldehyde is (5~10):(6~10):(8~25):(3~8).

[0009] By adopting the above technical solution, a modified phenolic amine curing agent is prepared by partially replacing phenol with thymol. The benzene ring of thymol has isopropyl and methyl groups, which improves the antioxidant properties, corrosion resistance, hydrolysis resistance, heat resistance, and hydrophobicity of the cured product, reduces the melt viscosity, and facilitates application.

[0010] In a preferred embodiment of the corrosion-resistant coating material, the aliphatic polyamine is triethylenetetramine or diethylenetriamine.

[0011] By adopting the above technical solution, both amines contain two primary amines and one to two secondary amines, and can undergo the Mannich reaction. The excess primary and secondary amines can also react with epoxy resins for polymerization.

[0012] In a preferred embodiment of the corrosion-resistant coating material, the waterproofing agent is polydimethylsiloxane or polyether-modified organosilicon.

[0013] By adopting the above technical solution, the waterproofing agent, due to its extremely low surface energy, will migrate to the surface of the coating to form a hydrophobic layer, effectively preventing water penetration and improving the water immersion resistance of the coating material.

[0014] In a preferred embodiment of the corrosion-resistant coating material, the corrosion inhibitor is benzotriazole or methylbenzotriazole.

[0015] By adopting the above technical solutions, these two corrosion inhibitor molecules can be adsorbed on the metal surface to form a monomolecular protective film, which inhibits the electrochemical corrosion of the metal.

[0016] In a preferred embodiment of the corrosion-resistant coating material, the lubricant is talc or mica powder.

[0017] By adopting the above technical solution, the lubricant increases the smoothness of the coating surface, reduces the curing shrinkage rate of the material, and improves hardness and wear resistance.

[0018] Secondly, this application proposes a method for preparing a corrosion-resistant coating material, and adopts the following technical solution.

[0019] A method for preparing a corrosion-resistant coating material, the method comprising: adding epoxy resin, modified phenolic amine curing agent, waterproofing agent, corrosion inhibitor, and lubricant into a reactor, continuously stirring to mix them evenly and allow a prepolymerization reaction to occur; in an inert atmosphere, controlling the temperature at 35~45℃, adding a non-polar solvent for rinsing; cooling to 10~25℃ and adding a polar solvent; removing impurities by vacuum distillation to obtain a semi-finished product; the finished product obtained after curing the semi-finished product is the corrosion-resistant coating material.

[0020] By employing the above technical solution, the modified phenolic amine curing agent molecule contains multiple primary and secondary amine groups. These amine groups attack the epoxy groups in the epoxy resin molecule, causing them to open the ring and undergo an addition polymerization reaction. During the prepolymerization reaction between the epoxy resin and the amine curing agent, the viscosity of the system gradually increases to obtain suitable application viscosity and storage stability. In the prepolymerization process, the waterproofing agent, corrosion inhibitor, and lubricant are completely dispersed in the system, preventing agglomeration and forming a homogeneous mixture. An inert atmosphere prevents oxygen in the air from oxidizing and degrading the curing agent or resin under heating conditions, which would lead to a darkening of the coating color or a decrease in performance. Adding a non-polar solvent for rinsing dissolves residual unreacted small molecule impurities such as phenols and aldehydes in the system, and removes these impurities by vacuum distillation. The process of adding non-polar and polar solvents to treat the reactants dilutes the reactant concentration, slowing down the rate of reaction and curing, making it less prone to curing. The process of curing semi-finished products to obtain finished products involves the interconnection of linear and branched molecules, ultimately forming a three-dimensional cross-linked network. This network firmly locks in corrosion inhibitors and lubricants, while waterproofing agents, due to their incompatibility and low surface energy, continuously migrate to the coating-air interface, eventually forming an effective hydrophobic barrier on the outermost layer of the coating. This results in a tough, dense three-dimensional network coating with excellent adhesion, corrosion resistance, and hydrophobicity.

[0021] A preferred embodiment of the preparation method of the corrosion-resistant coating material is that the modified phenolic amine curing agent is obtained by the following method: phenol, thymol, and aliphatic polyamine are added to a closed reactor, the temperature is controlled at 53~60℃, and the mixture is continuously stirred to obtain a liquid mixture. After the formaldehyde aqueous solution is added dropwise, the temperature is raised to 90~100℃ and the reaction is completed. After dehydration, the modified phenolic amine curing agent is obtained.

[0022] By employing the above technical solution, phenol, thymol, and aliphatic polyamines are added to a closed reactor, the temperature is controlled at 53-60℃, and continuous stirring ensures full contact of the reactants. The dropwise addition of formaldehyde aqueous solution effectively controls the Mannich reaction rate, preventing excessive boiling or localized overheating due to excessive exothermic reactions, thus ensuring a stable and complete reaction. Phenol, thymol, and aliphatic polyamines all have boiling points above 100℃ and are liquid at 90-100℃, allowing for thorough reaction. Formaldehyde circulates between the bottom reaction liquid and the cavity in the closed reactor. As the reaction proceeds, the equilibrium shifts towards the formation of the modified phenolic amine curing agent, with more and more formaldehyde returning from the air to the reaction liquid to participate in the Mannich reaction. In this Mannich reaction, the carbonyl group of formaldehyde undergoes electrophilic substitution with the active hydrogen at the ortho or para position on the benzene ring of phenol or thymol, generating hydroxymethylphenol. The nitrogen atom on an aliphatic polyamine possesses a lone pair of electrons, exhibiting strong nucleophilicity. It directly attacks formaldehyde to form hydroxymethylamine, which then reacts with phenol, or directly attacks the previously formed hydroxymethylphenol. Both methods result in a benzylamine structure, which is the modified phenolic amine curing agent. The final modified phenolic amine curing agent is a viscous liquid containing multiple amine groups and phenolic nuclei. It retains the property of amine curing agents that can react with epoxy resins at room temperature, and the introduction of phenolic nuclei and thymol imparts better adhesion, toughness, and corrosion resistance to the cured coating.

[0023] In summary, the corrosion-resistant coating material and its preparation method of this application have the following beneficial effects: the coating material has excellent adhesion and significantly extends the service life of metal instruments after use; through the synergistic effect of modified phenolic amine curing agent and epoxy resin, the curing efficiency and adhesion are improved while maintaining corrosion resistance; it is suitable for high-requirement fields such as medical devices and has good application prospects. Attached Figure Description

[0024] Figure 1 This is a flowchart for Example 1. Detailed Implementation

[0025] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Example

[0026] This embodiment prepares a corrosion-resistant coating material, referring to... Figure 1 The preparation method is as follows.

[0027] Preparation of modified phenolic amine curing agent: At room temperature, phenol, thymol, and triethylenetetramine (aliphatic polyamine) were added to a closed reactor. The temperature was controlled at 53°C. Solid phenol and thymol melted and mixed with the liquid aliphatic polyamine to obtain a liquid mixture. The mixture was stirred continuously, and a 38wt% formaldehyde aqueous solution was added dropwise for 30 minutes. Then, the temperature was raised to 90°C and reacted for 2 hours to ensure complete reaction. Subsequently, the temperature was lowered to 85°C, and vacuum dehydration was performed to obtain the modified phenolic amine curing agent. In this step, the mass ratio of phenol, thymol, aliphatic polyamine, and formaldehyde (pure formaldehyde contained in the formaldehyde aqueous solution) was 5:10:8:8.

[0028] By weight, 80 parts epoxy resin, 20 parts modified phenolic amine curing agent, 2 parts polydimethylsiloxane (waterproofing agent), 10 parts benzotriazole (corrosion inhibitor), and 40 parts talc (lubricant) were added to a reactor and stirred continuously for 10 hours to ensure uniform mixing and prepolymerization. Nitrogen gas was introduced into the reactor to maintain an inert atmosphere, and the temperature was controlled at 35°C. 3 parts toluene (non-polar solvent) were added for rinsing for 1 hour, and the temperature was lowered to 10°C after approximately 10 minutes. Then, 23 parts ethanol (polar solvent) were added to dissolve impurities, followed by vacuum distillation to remove impurities, yielding a semi-finished product. The semi-finished product was then applied to a substrate and allowed to cure under ambient temperature and air. This semi-finished product is a corrosion-resistant coating material; after curing on the substrate, it represents the finished product of this corrosion-resistant coating material. Example

[0029] This embodiment prepares a corrosion-resistant coating material, and the preparation method is as follows.

[0030] Preparation of modified phenolic amine curing agent: At room temperature, phenol, thymol, and triethylenetetramine (aliphatic polyamine) were added to a closed reactor. The temperature was controlled at 60°C. Solid phenol and thymol melted and mixed with the liquid aliphatic polyamine to obtain a liquid mixture. The mixture was stirred continuously, and a 38wt% formaldehyde aqueous solution was added dropwise for 30 minutes. Then, the temperature was raised to 99°C and reacted for 2 hours to ensure complete reaction. Subsequently, the temperature was lowered to 85°C, and vacuum dehydration was performed to obtain the modified phenolic amine curing agent. In this step, the mass ratio of phenol, thymol, aliphatic polyamine, and formaldehyde (pure formaldehyde contained in the formaldehyde aqueous solution) was 10:6:25:3.

[0031] By weight, 100 parts epoxy resin, 5 parts modified phenolic amine curing agent, 5 parts polydimethylsiloxane (waterproofing agent), 5 parts benzotriazole (corrosion inhibitor), and 55 parts talc (lubricant) were added to a reactor and stirred continuously for 10 hours to ensure uniform mixing and prepolymerization. Nitrogen gas was introduced into the reactor to maintain an inert atmosphere, and the temperature was controlled at 45°C. 3 parts toluene (non-polar solvent) were added for rinsing for 1 hour, and the temperature was lowered to 25°C after approximately 10 minutes. Then, 23 parts ethanol (polar solvent) were added to dissolve impurities, followed by vacuum distillation to remove impurities, yielding a semi-finished product. The semi-finished product was then applied to a substrate and allowed to cure under ambient temperature and air. This semi-finished product is a corrosion-resistant coating material; after curing on the substrate, it represents the finished product of this corrosion-resistant coating material. Example

[0032] This embodiment prepares a corrosion-resistant coating material, and the preparation method is as follows.

[0033] Preparation of modified phenolic amine curing agent: At room temperature, phenol, thymol, and diethylenetriamine (aliphatic polyamine) were added to a closed reactor. The temperature was controlled at 56°C. Solid phenol and thymol melted and mixed with the liquid aliphatic polyamine to obtain a liquid mixture. The mixture was stirred continuously, and a 38wt% formaldehyde aqueous solution was added dropwise for 30 minutes. Then, the temperature was raised to 95°C and reacted for 2 hours to ensure complete reaction. Subsequently, the temperature was lowered to 85°C, and vacuum dehydration was performed to obtain the modified phenolic amine curing agent. In this step, the mass ratio of phenol, thymol, aliphatic polyamine, and formaldehyde (pure formaldehyde contained in the formaldehyde aqueous solution) was 7:8:16:5.

[0034] By weight, 90 parts epoxy resin, 12 parts modified phenolic amine curing agent, 3 parts polyether modified silicone (waterproofing agent), 7 parts methylbenzotriazole (corrosion inhibitor), and 48 parts mica powder (lubricant) were added to a reactor and stirred continuously for 10 hours to ensure uniform mixing and prepolymerization. Nitrogen gas was introduced into the reactor to maintain an inert atmosphere, and the temperature was controlled at 40°C. 3 parts toluene (non-polar solvent) were added for rinsing for 1 hour, and the temperature was lowered to 20°C after approximately 10 minutes. Then, 23 parts ethanol (polar solvent) were added to dissolve impurities, followed by vacuum distillation to remove impurities, yielding a semi-finished product. The semi-finished product was then applied to a substrate and allowed to cure under ambient temperature and air. This semi-finished product is a corrosion-resistant coating material; after curing on the substrate, it represents the finished product of this corrosion-resistant coating material.

[0035] Comparative Example 1 This comparative example prepares a corrosion-resistant coating material. The only difference from Example 1 is that thymol is replaced with an equal mass of phenol, and finally, a semi-finished product and a finished corrosion-resistant coating material are obtained.

[0036] Comparative Example 2 This comparative example prepares a corrosion-resistant coating material. The only difference from Example 3 is that thymol is replaced with an equal mass of cashew phenol, and finally, semi-finished and finished corrosion-resistant coating materials are obtained.

[0037] Experimental Example 1 The semi-finished products of Examples 1-3 and Comparative Examples 1-2 were coated onto the surface of a titanium alloy substrate (Ti-6Al-4V titanium alloy) and allowed to cure statically in a room temperature environment and air atmosphere to obtain titanium alloy implants coated with corrosion-resistant coating materials. Adhesion and corrosion resistance tests were then conducted.

[0038] Adhesion: For each example and comparative example, two parallel titanium alloy implants coated with the corrosion-resistant coating material were prepared. One implant was used to test the initial bonding strength between the corrosion-resistant coating and the titanium alloy; the other implant was immersed in a simulated body fluid at pH 7.4 for 60 days, and then removed for further testing of the bonding strength between the corrosion-resistant coating and the titanium alloy.

[0039] The bonding strength was tested using an MFT-000 multifunctional material surface performance tester. The specific operating procedure was as follows: a conical diamond indenter (120° angle, 200μm radius) was used to continuously apply a normal force of 0.1~20N at a loading rate of 20N / min and a scratching speed of 1mm / min. Simultaneously, sensors continuously recorded the changes in frictional force, normal force, and acoustic signal with the scratch distance. Critical loads Lc1 and Lc2 were set to evaluate the coating failure mode. Lc1 is called the first critical load, indicating that the coating is locally scratched through. As the normal load gradually increases, the diamond indenter scratches the coating in contact with the substrate, cracks appear at the bottom and sides of the scratch, and gradually peeling occurs until the coating completely detaches (scratch morphology is observed using an optical microscope). At this point, the frictional force exhibits a sudden change, and an inflection point can be observed on the friction curve. The load at this inflection point is defined as the second critical load Lc2, which represents the bonding strength between the corrosion-resistant coating and the titanium alloy substrate.

[0040] Corrosion resistance: Using simulated body fluid at pH 7.4 as the electrolyte, each experimental group used a titanium alloy implant coated with a corrosion-resistant material as the working electrode, a platinum sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. Potentiodynamic polarization tests were conducted using an SP15-20A electrochemical workstation, and the results were compared with uncoated titanium alloy implants. During the test, an equilibrium open-circuit potential (Eocp) was established over 1800 s. The Tafel polarization curves were then recorded at a scan rate of 0.01 V / s, and the corrosion potential of the tested sample was obtained by linear extrapolation of the detected Tafel curves. A more positive corrosion potential indicates a lower tendency for the titanium alloy implant to corrode in simulated human body fluid.

[0041] The adhesion and corrosion resistance test results of titanium alloy implants coated with corrosion-resistant coating materials are shown in Table 1 below.

[0042] Table 1 Performance test results of titanium alloy implants coated with corrosion-resistant coating material

[0043] The initial adhesion between the corrosion-resistant coating materials of Examples 1-3 and the titanium alloy implants reached 9.19-9.72 N, and the adhesion remained at 9.17-9.69 N after immersion for 60 days. The initial adhesion between the corrosion-resistant coating materials of Comparative Examples 1-2 and the titanium alloy implants was 6.83-7.16 N, and the adhesion after immersion for 60 days was 6.69-7.08 N. This indicates that the corrosion-resistant coating materials of Examples 1-3 have strong adhesion to the titanium alloy implants and are not easily corroded and detached.

[0044] The corrosion potential of the uncoated titanium alloy implant is as high as -0.73V, while the corrosion potential of the titanium alloy implants prepared with the coating materials of Examples 1-3 is -0.06 to -0.05V, and the corrosion potential of the titanium alloy implants prepared with the coating materials of Comparative Examples 1-2 is -0.18 to -0.14V. The comparison shows that the corrosion potential of Examples 1-3 is lower, indicating that the titanium alloy implants of Examples 1-3 are less susceptible to corrosion. Titanium alloy implants are more easily corroded without a coating material.

[0045] The above results indicate that a modified phenolic amine curing agent is obtained by using phenol, thymol, aliphatic polyamines, and formaldehyde through the Mannich reaction. This modified phenolic amine curing agent is then mixed with epoxy resin, waterproofing agent, corrosion inhibitor, and lubricant. The modified phenolic amine curing agent cures the epoxy resin and encapsulates the waterproofing agent, corrosion inhibitor, and lubricant. The resulting coating material, when applied to the surface of a metal material, exhibits high adhesion to the metal material and effectively protects the metal material from the corrosive effects of bodily fluids.

[0046] The corrosion-resistant coating material of this application can be used not only on the surface of implant metal materials, but also on the surface of other substrates, and can also be used as a waterproof and anti-corrosion coating for concrete buildings and metal pipes.

[0047] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A corrosion resistant coating material, characterized by, The corrosion-resistant coating material comprises the following components in parts by mass: epoxy resin 80-100 parts, modified phenolic amine curing agent 5-20 parts, waterproof agent 2-5 parts, corrosion inhibitor 5-10 parts, and lubricant 40-55 parts; The modified phenolic amine curing agent is obtained by Mannich reaction of phenol, thymol, aliphatic polyamine and formaldehyde.

2. The corrosion resistant coating material of claim 1, wherein, The mass ratio of phenol, thymol, aliphatic polyamine and formaldehyde is (5-10):(6-10):(8-25):(3-8).

3. The corrosion resistant coating material according to claim 1 or 2, characterized in that, The aliphatic polyamine is triethylenetetramine or diethylenetriamine.

4. The corrosion resistant coating material of claim 1, wherein, The waterproof agent is polydimethylsiloxane or polyether-modified silicone.

5. The corrosion resistant coating material of claim 1, wherein The corrosion inhibitor is benzotriazole or methylbenzotriazole.

6. The corrosion resistant coating material of claim 1, wherein, The lubricant is talc or mica powder.

7. A method of producing a corrosion resistant coating material as claimed in any one of claims 1 to 6, characterised in that, The preparation method comprises the following steps: The epoxy resin, modified phenolic amine curing agent, waterproof agent, corrosion inhibitor and lubricant are put into a reactor, continuously stirred to mix uniformly and pre-polymerize, and then rinsed with non-polar solvent in an inert atmosphere at a temperature of 35-45 DEG C; after cooling to 10-25 DEG C, polar solvent is added, and impurities are removed by reduced pressure distillation to obtain a semi-finished product; the semi-finished product is cured to obtain a finished product, which is the corrosion-resistant coating material.

8. The method of claim 7, wherein the corrosion resistant coating material is prepared by a process comprising: The modified phenolic amine curing agent is obtained by the following method: Phenol, thymol and aliphatic polyamine are put into a sealed reactor, the temperature is controlled to 53-60 DEG C, and continuous stirring is performed to obtain a liquid mixture; then, formaldehyde aqueous solution is added dropwise, and after heating to 90-100 DEG C and complete reaction, the modified phenolic amine curing agent is obtained by dehydration.

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