阅读说明：本技术 胍基有机化合物及其制备方法和应用 (Guanidyl organic compound and preparation method and application thereof ) 是由 刘娅莉 李季 罗小虎 朱日龙 楚宗霖 唐洪 陈博 周城良 潘心宇 袁天赐 李钊 于 2020-11-17 设计创作，主要内容包括：本发明涉及一种胍基有机化合物及其制备方法和应用,其具有如下通式I所示的结构,其中,R选自(CH-2)-nCONH-2,n为1～6的整数。本发明的胍基有机化合物中胍基官能团提供抗菌抗生物结垢能力,同氨基酸相近似的结构提供缓蚀能力,从而创造性地将抗生物结垢和缓蚀功能结合在一起,而且由其构建的表面防护膜具有较高的电化学阻抗值和优异的抗溶剂污染等粘附与抗生物质沾污及抗结垢能力。(The invention relates to a guanidyl organic compound, a preparation method and application thereof, wherein the guanidyl organic compound has a structure shown as a general formula I, wherein R is selected from (CH) 2 ) n CONH 2 And n is an integer of 1 to 6. The guanidine functional group in the guanidine organic compound provides antibacterial and anti-biofouling capability, and the structure similar to amino acid provides corrosion inhibition capability, so that the anti-biofouling and corrosion inhibition functions are creatively combined, and the surface protective film constructed by the guanidine organic compound has higher electrochemical impedance value and excellent adhesion, anti-biomass fouling and anti-fouling capabilities such as anti-solvent pollution and the like.)

1. A guanidino organic compound having the structure shown in formula I:

wherein R is selected from- (CH)₂)_nCONH₂And n is an integer of 1 to 6.

2. The guanidino organic compound according to claim 1, wherein n is an integer of 1 to 2.

3. The guanidino organic compound of claim 1 having the structure of formula II:

4. a method for producing a guanidino organic compound according to any one of claims 1 to 3, characterized in that the guanidino organic compound is obtained by an addition reaction of a first compound represented by the general formula III:

wherein R is selected from (CH)₂)_nCONH₂And n is an integer of 1 to 6.

5. Use of a guanidino organic compound according to any of claims 1 to 3 as corrosion inhibitor.

6. A surface treatment liquid comprising the guanidino organic compound according to any one of claims 1 to 3.

7. The surface treatment liquid according to claim 6, comprising the following components in parts by mass: 3-20 parts of a lithium source, 0.5-20 parts of a promoter, 0.1-20 parts of a guanidyl organic compound and 0.1-20 parts of a fluorine-containing organic silicon additive.

8. The surface treatment fluid of claim 7, wherein the lithium source is one or more of lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, and lithium hydroxide; the accelerant is one or more of sodium nitrate, sodium nitrite, sodium fluoride, trisodium phosphate and simethicone; the fluorine-containing organosilicon additive is one or more of 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 1H,2H, 2H-perfluorodecyltrimethoxysilane, 1H,2H, 2H-perfluoroheptadecyltrimethyloxysilane and trichloro (1H,1H,2H, 2H-perfluorooctyl) silane.

9. Use of the guanidino organic compound of any one of claims 1 to 3 or the surface treatment liquid of any one of claims 6 to 8 for producing a conversion coating.

10. A conversion coating obtained by treating the surface treatment liquid according to any one of claims 6 to 8.

Technical Field

The invention relates to the technical field of surface treatment, in particular to a guanidyl organic compound and a preparation method and application thereof.

Background

Biofouling and microbial corrosion (MIC) occur in many industries, mainly characterized by microbial adhesion to the surface of metal facilities, resulting in corrosion, aging failure of the material. Generally, the microbial corrosion process occurs mainly under a biofilm composed of extracellular polymeric substances produced during the microbial metabolism. Because of the covering of the biological film, the corrosion environment of the metal is different from the environment outside the biological film, the corrosion process is more complicated, and the activity of microorganisms in the biological film causes the change of dissolved oxygen, pH, organic and inorganic substances between the metal and the water solution interface, thereby forming the most basic oxygen concentration difference and other concentration difference batteries in the electrochemical theory. This process has significant implications for energy production, chemical processes, petrochemical, marine and military. The economic losses caused by microbial corrosion are enormous. According to statistics, the microbial corrosion accounts for 20% in the corrosion damage of metals and building materials, more than 75% in oil wells and 50% in buried pipelines and cables have failures caused by the microbial corrosion (mainly sulfate reduction process), and in addition, marine equipment such as underwater sonar is also often corroded, especially bacteria corrosion, because of the tenacious attachment of marine organisms, aluminum alloy equipment is corroded, so that the sonar cannot normally work seriously, and the normal use of monitoring equipment is not facilitated. Much of the research on microbial corrosion of materials in recent decades has shown that almost all commonly used materials produce microbial induced corrosion. Therefore, the research on the corrosion mechanism and characteristics of several common microorganisms and the prevention and treatment of microbial corrosion are very important. Fungicides such as tributyltin have been used to control biological contamination and microbial corrosion as early as the 50's of the 20 th century. However, the release of metallic tin-containing biocides from antifouling paints threatens human and marine mammal health and has adverse ecological and environmental effects.

The aluminum alloy has the characteristics of low density, high strength and high recoverability, is widely applied to the fields of aerospace, transportation, electronic products and the like, and is an important guarantee for reducing the structure weight and the energy consumption of large airplanes, automobiles, high-speed trains, military equipment, mariculture and the like. However, the intermetallic compound in the aluminum alloy can be used as an anode or a cathode, so that the aluminum alloy is susceptible to local corrosion in the natural and use environments, and the smooth operation of equipment is influenced, and even disastrous results are caused. Therefore, the research on the anti-corrosion, anti-fouling and fouling-resistant performance of the anti-corrosion, anti-fouling and fouling-resistant coating of the aluminum alloy and the anti-corrosion and anti-fouling performance of the anti-corrosion and fouling-resistant coating in the use environment are one of important subjects and hot spots in the field of global material science, and the development of a multifunctional surface anti-corrosion and anti-fouling surface protection method for the surface of.

At present, lightweight metal materials such as aluminum alloy and the like are increasingly applied, and ocean economy, particularly deep sea resource development, puts forward higher and higher requirements on corrosion resistance, pollution resistance and antibacterial property for the aluminum alloy and the like. Most of the existing marine antibacterial coatings are organic antibacterial coatings, and biomass adhesion and microbial corrosion caused by the biomass adhesion are reduced by adding a large amount of bacteriostatic (bactericidal) agents in a coating formula. However, this method is not suitable for the high corrosion-resistant and corrosion-resistant conversion coating directly obtained by chemical method on the metal surface, because some metal ions in the antibacterial agent promote corrosion of aluminum alloy; in addition, the antimicrobial agent itself is consumable and the antimicrobial effect diminishes over time.

Super-hydrophobic materials have been developed rapidly in recent years, and surfaces exposed to water drops are not always wet, and some living organisms in nature, such as lotus leaves, water striders, etc., have superior water repellency, which is called super-hydrophobic. The hydrophobic property of the surface of the reinforced material delays the time of a corrosive medium reaching the surface of a matrix, which has a good effect on improving the corrosion resistance of the metal surface and prolonging the service life, a micro-nano coarse structure is constructed on the surface by reducing solid-liquid contact through a common means, the nano structure can provide the water repellency, and the micro-scale structure design is beneficial to maintaining the superhydrophobicity of the surface for a long time. Meanwhile, a layer of self-assembled complex film with extremely strong surface hydrophobicity is added on the structure, so that the surface energy is greatly reduced, and a super-hydrophobic surface with a contact angle larger than 150 degrees is obtained. On the basis of high corrosion resistance, the surface is endowed with special properties such as contamination resistance, self-antibiosis, self-cleaning and the like, the application field of the metal is expanded, and the service life of the metal is prolonged.

Disclosure of Invention

Based on the above, there is a need for providing a guanidino organic compound with excellent anti-biofouling properties, which can be used as a corrosion inhibitor added into a surface treatment solution to construct a protective film with controllable structure, high electrochemical impedance, high corrosion resistance and excellent anti-biofouling capability for an aluminum alloy surface. In addition, the substrate material with the rough micro-nano structure can be used as a substrate, and the anti-pollution capability of the film layer is further improved by adopting fluorosilane treatment through a self-assembly method.

A guanidino organic compound having the structure shown in formula I:

wherein R is selected from (CH)₂)_nCONH₂And n is an integer of 1 to 6.

The guanidino functional group in the guanidino organic compound provides antibacterial and anti-biofouling capability, and the structure similar to amino acid provides corrosion inhibition capability, so that the anti-biofouling and corrosion inhibition functions are creatively combined, and the aluminum alloy surface protective film constructed by the guanidino organic compound has higher electrochemical impedance value and excellent adhesion and anti-biomass fouling and anti-fouling capabilities of resisting solvent pollution and the like. The guanidine compound basically does not produce target-target specific combination with bacteria, but achieves the final sterilization purpose through an electrostatic attraction mode with cell membranes, so that the guanidine compound is not easy to generate drug resistance. Meanwhile, the outer layer of the cell membrane of the mammal is electrically neutral, and the outer layer of the cell membrane of the bacteria/fungi is negatively charged, so that the guanidine polymer with positive charge has strong selectivity on the cell membrane of the bacteria or fungi, and the toxicity of the guanidine polymer on the cells of the mammal is further reduced. In addition, compared with the amino group with positive charge, the guanidino can be ionized in a wider pH range, and the guanidino is combined with the cell membrane in a double hydrogen bond mode, is combined with the cell membrane more firmly and has stronger antibacterial property. Meanwhile, the inhibitor containing guanidino, which has a structure similar to that of amino acid, is efficient and environment-friendly, has a structure which is easier to adsorb on the surfaces of metals such as aluminum alloy and the like to play a corrosion inhibition effect, can be gradually degraded even if finally released in the environment such as water and the like, and cannot cause environmental pollution and continuous harm to wild animals and plants.

In one embodiment, n is an integer of 1-2.

In one embodiment, the structure is as shown in formula II:

the invention also provides a preparation method of the guanidyl organic compound, wherein the guanidyl organic compound is obtained by performing addition reaction on a first compound shown as a general formula III and cyanamide:

wherein R is selected from (CH)₂)_nCONH₂And n is an integer of 1 to 6.

In one embodiment, the method comprises the following steps: and respectively dissolving the first compound and the cyanamide in an acid solution, mixing and reacting at 5-15 ℃ for 48-72 hours.

The invention also provides an application of the guanidino organic compound as a corrosion inhibitor.

The invention also provides a surface treatment liquid which comprises the guanidine-based organic compound.

In one embodiment, the composition comprises the following components in parts by mass: 3-20 parts of a lithium source, 0.5-20 parts of a promoter, 0.1-20 parts of a guanidyl organic compound and 0.1-20 parts of a fluorine-containing organic silicon additive.

In one embodiment, the lithium source is one or more of lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, and lithium hydroxide; the accelerant is one or more of sodium nitrate, sodium nitrite, sodium fluoride, trisodium phosphate and simethicone; the fluorine-containing organosilicon additive is one or more of 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 1H,2H, 2H-perfluorodecyltrimethoxysilane, 1H,2H, 2H-perfluoroheptadecyltrimethyloxysilane and trichloro (1H,1H,2H, 2H-perfluorooctyl) silane.

The invention also provides application of the guanidino organic compound or the surface treatment liquid in preparation of a conversion coating.

The invention also provides a conversion coating obtained by treating the surface treatment liquid.

Drawings

FIG. 1 is a nuclear magnetic resonance spectrum (NMR) of the guanidino organic compound 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutanoic acid prepared in example 1; wherein (a) is D₂Carbon spectrum in O (heavy water), (b) is D₂Hydrogen spectrum in O (heavy water);

FIG. 2 is a mass spectrum of 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutanoic acid, a guanidino organic compound, prepared in example 1;

FIG. 3 is an infrared spectrum of the guanidino organic compound 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutanoic acid prepared in example 1;

FIG. 4 is a SEM image of a high power scanning electron microscope of the surface morphology of AFLDHs of the lithium aluminum hydrotalcite conversion coating on the surface of the aluminum alloy sampled in example 2;

FIG. 5 is an electronic digital photograph of the appearance of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy sampled from example 2 after the film is immersed in a corrosive environment for 28 days;

FIG. 6 is an electronic digital photograph of the appearance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after a 280-hour neutral salt spray corrosion test;

FIG. 7 is a comparison graph of electrochemical AC impedance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after soaking in a corrosive environment for 0 day;

FIG. 8 is a graph comparing the electrochemical AC impedance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after being soaked in a corrosive environment for 1 day;

FIG. 9 is a comparison graph of electrochemical AC impedance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after being soaked in a corrosive environment for 5 days;

FIG. 10 is a graph comparing the electrochemical AC impedance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after being soaked in a corrosive environment for 14 days;

FIG. 11 is a graph comparing the electrochemical AC impedance of the lithium aluminum hydrotalcite conversion film sampled from example 2 and obtained on the surface of the aluminum alloy after soaking in a corrosive environment for 28 days;

FIG. 12 is a graph comparing electrochemical AC impedance of different R-based corrosion inhibitor modified aluminum alloy surface lithium aluminum hydrotalcite conversion films in a corrosive environment;

FIG. 13 shows example 4 where R is CH₂CONH₂An electronic digital photo of the plane water contact angle of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy is taken;

FIG. 14 shows example 4 where R is CH₂An electronic digital photo of the plane water contact angle of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy when COOH is used;

FIG. 15 shows example 4 in which R is CH₂CONH₂Lithium-aluminum hydrotalcite on surface of aluminum alloyElectronic digital photos of the drops of the water (a), the oil drops (b), the milk (c), the tea (d), the red wine (e) and the soil solution (f) on the surface of the chemical film;

FIG. 16 is a digital photograph of colonies of Escherichia Coli (EC), Bacillus Subtilis (BS) and Sulfate Reducing Bacteria (SRB) resistant films of lithium aluminum hydrotalcite on the surface of aluminum alloy sampled from example 5;

FIG. 17 is a SEM photograph of high power scanning electron microscope images of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy sampled from example 5, which is resistant to Escherichia Coli (EC), Bacillus Subtilis (BS) and Sulfate Reducing Bacteria (SRB).

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The guanidyl organic compound of one embodiment of the present invention has a structure represented by the following general formula I:

wherein R is selected from (CH)₂)_nCONH₂And n is an integer of 1 to 6.

The guanidino functional group in the guanidino organic compound provides antibacterial and anti-biofouling capability, and the structure similar to amino acid provides corrosion inhibition capability, so that the anti-biofouling and corrosion inhibition functions are creatively combined, and the aluminum alloy surface protective film constructed by the guanidino organic compound has higher electrochemical impedance value and excellent adhesion and anti-biomass fouling and anti-fouling capabilities of resisting solvent pollution and the like. The guanidine compound basically does not produce target-target specific combination with bacteria, but achieves the final sterilization purpose through an electrostatic attraction mode with cell membranes, so that the guanidine compound is not easy to generate drug resistance. Meanwhile, the outer layer of the cell membrane of the mammal is electrically neutral, and the outer layer of the cell membrane of the bacteria/fungi is negatively charged, so that the guanidine polymer with positive charge has strong selectivity on the cell membrane of the bacteria or fungi, and the toxicity of the guanidine polymer on the cells of the mammal is further reduced. In addition, compared with the amino group with positive charge, the guanidino can be ionized in a wider pH range, and the guanidino is combined with the cell membrane in a double hydrogen bond mode, is combined with the cell membrane more firmly and has stronger antibacterial property. Meanwhile, the inhibitor containing guanidino, which has a structure similar to that of amino acid, is efficient and environment-friendly, has a structure which is easier to adsorb on the surfaces of metals such as aluminum alloy and the like to play a corrosion inhibition effect, can be gradually degraded even if finally released in the environment such as water and the like, and cannot cause environmental pollution and continuous harm to wild animals and plants.

In a specific example, n is an integer of 1-2, i.e., R is CH₂CONH₂Or CH₂CH₂CONH₂. Preferably, the guanidino organic compound has the structure shown in formula II, namely 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid.

In one embodiment of the present invention, the method for producing a guanidino organic compound comprises an addition reaction of a first compound represented by general formula III:

wherein R is selected from (CH)₂)_nCONH₂And n is an integer of 1 to 6.

In one specific example, the preparation method comprises the following steps: respectively dissolving the first compound and cyanamide in an acid solution, mixing, and reacting at 5-15 ℃ for 48-72 hours, wherein the reaction chemical formula is shown as follows.

In a specific example, the molar ratio of the first compound to the cyanamide is (1-1.2): 1, and the first compound is used as a raw material in a slight excess amount so as to maximize the conversion rate of the synthesis reaction and to make the cyanamide (cyanamide) react completely as much as possible.

Alternatively, the acid solution is a common strong acid solution such as a hydrochloric acid solution, a sulfuric acid solution, a nitric acid solution, or the like. Preferably, the pH value of the acid solution is 4-5, and side reaction hydrolysis reaction and self polymerization reaction of cyanamide can be avoided by controlling the pH value. Preferably, the molar ratio of the first compound to the acid in the acid solution during dissolution is (2-2.5): 1, and the molar ratio of the cyanamide to the acid in the acid solution is (2-2.4): 1.

Optionally, the following steps are also included after the reaction: and drying by methods such as rotary evaporation, freeze drying or vacuum oven drying until the reaction solvent basically disappears, filtering and washing the precipitate, adding water into the precipitate for redissolving, and then carrying out rotary evaporation, recrystallization, filtration, water washing and drying to obtain the guanidino organic compound with higher purity. Preferably, the crystal obtained by recrystallization is dried at 95-105 ℃ after washing with water. Alternatively, the first compound is asparagine or glutamine, or the like.

The surface treatment liquid according to an embodiment of the present invention includes the guanidino organic compound.

In a specific example, the surface treatment liquid comprises the following components in parts by mass: 3 to 20 parts of lithium source, 0.5 to 20 parts of accelerant, 0.1 to 20 parts of guanidyl organic compound and 0.1 to 20 parts of fluorine-containing organic silicon additive.

The guanidyl organic compound and the surface treatment liquid can be widely applied to various surface treatment systems such as an anodic oxidation system and a hydrotalcite system (such as lithium aluminum hydrotalcite, magnesium aluminum hydrotalcite, zinc aluminum hydrotalcite and the like) as an intercalation modifier to construct a multifunctional conversion membrane with corrosion resistance, super hydrophobicity, antibacterial and anti-biological scaling properties, and the wide application performance evaluation of the guanidyl organic compound is shown in table 1. The supermolecular assembly material hydrotalcite-like Layered compound (LDH) with nano-scale structure is composed of two hydroxides, the structure formed by exchanging interlayer anions is called intercalation hydrotalcite, and the intercalation hydrotalcite, hydrotalcite-like and hydrotalcite-like are collectively called hydrotalcite-like intercalation material (LDHs). By utilizing the unique characteristics of the intercalated layer of the hydrotalcite and through the structural design, compounding and the like of the inhibitor, the leaching of the inhibitor can be controlled, the inhibitory substances with enough concentration can be provided for effective protection of aluminum, the lasting effect is ensured, and the functions of controllable release and lasting long-acting antibiosis, adhesion resistance and corrosion resistance after surface treatment are increased. Compared with zinc oxide, titanium dioxide, ferroferric oxide and composite oxides thereof as well as silver salt-containing bactericidal materials, the LDHs bactericidal material has the following advantages: firstly, the effective sterilization components are highly dispersed, and the sterilization efficiency is high; secondly, the dispersion in the synthetic material is good, and the mechanical property is excellent; the LDHs has low density and high light transmittance; fourthly, the light resistance and the weather resistance are good, and the decoloring is not easy.

TABLE 1

In a specific example, the lithium source is one or more of lithium nitrate, lithium carbonate, lithium sulfate, lithium phosphate, and lithium hydroxide. Optionally, the accelerator is one or more of sodium nitrate, sodium nitrite, sodium fluoride, trisodium phosphate, and simethicone. Optionally, the fluorosilicone additive is one or more of 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 1H,2H, 2H-perfluorodecyltrimethoxysilane, 1H,2H, 2H-perfluoroheptadecyltrimethoxysilane, and trichloro (1H,1H,2H, 2H-perfluorooctyl) silane. Optionally, the surface treatment liquid may further include additives such as aspartic acid, arginine, asparagine, guanidinoacetic acid, and the like.

The method for preparing the surface treatment liquid according to the embodiment of the present invention includes the steps of: dissolving a lithium source, a promoter, a guanidyl organic compound and a fluorine-containing organic silicon additive in water, and mixing to obtain the surface treatment liquid.

Optionally, the surface treatment liquid is used by the following method: diluting the surface treatment liquid by 4-10 times to obtain a working liquid with a pH value of 9-11. The conversion film formed on the surface of the alloy is easy to be dissolved in working solution for the second time when the pH value is higher than the working pH range, so that the surface of the film is uneven and not compact enough; below the working pH range, it is difficult to grow a hydroxide conversion film.

The method for producing a conversion coating according to an embodiment of the present invention includes steps S1 to S3:

s1, pretreatment of the alloy surface: degreasing the alloy in acid, washing with water, degreasing in alkali, washing with water, brightening, and washing with water to remove dirt on the surface of the alloy;

s2, alloy conversion treatment: diluting the surface treatment liquid to obtain a working liquid, and then placing the alloy in the working liquid for chemical conversion surface treatment, wherein the treatment time is 10-50 min, and the treatment temperature is 40-60 ℃;

and S3, washing the alloy subjected to conversion treatment with deionized water, baking the alloy in a vacuum oven at 90-105 ℃ for 10-20 min, and cooling to obtain the surface-modified hydrotalcite conversion film.

Optionally, the alloy is an aluminum alloy, and a conversion film formed on the surface of the aluminum alloy is a hydrophobic antibacterial anti-corrosion anti-biofouling lithium aluminum hydrotalcite conversion film. Preferably, the surface treatment liquid is diluted 4 to 10 times, and the pH value of the diluted surface treatment liquid is 9 to 11, preferably 9.5 to 10.5. A large number of tests show that when the pH value is more than or equal to 11.0, the film forming speed is too high, the conversion film covers the surface of the matrix unevenly, and the corrosion resistance of the film is reduced; when the pH value is less than or equal to 9.0, the aluminum alloy is too slowly dissolved, and Al³⁺The ion source is insufficient and the resulting corrosion resistance is poor.

In a specific example, the time of the chemical conversion surface treatment is 10 to 50min, preferably 20 to 25min, and the temperature is 40 to 60 ℃, preferably 45 to 55 ℃. The film forming time is insufficient, and the conversion film on the surface of the alloy is not uniform enough; the film forming time is too long, the corrosion resistance of the film is not improved, and the adhesive force of the film is influenced. The film forming speed of the conversion film is accelerated due to overhigh temperature, the film layer is loose, and the corrosion resistance is reduced; if the temperature is too low, the film layer is slowly formed, and the obtained film layer is sparse and not compact enough.

The method can form a uniform and compact hydrotalcite conversion film on the surface of the alloy, and the preparation method of the surface treatment liquid has simple process, does not contain toxic chromate and phosphate, is environment-friendly, has short conversion treatment time and moderate treatment temperature, and does not need post-treatment. The conversion coating on the surface of the alloy obtained after surface treatment and drying has excellent corrosion resistance, hydrophobic antibacterial property and anti-biological scaling property, and can be used for outer layer corrosion prevention of alloy components and surface treatment before coating. Therefore, the guanidino organic compound can be used as a substitute for tributyltin bactericides and single-function corrosion inhibitors.

Compared with the prior art, the invention has the following advantages:

(1) the guanidino organic compound series products synthesized by the method have simple process, high product purity and no generation of toxic and harmful byproducts;

(2) the raw materials of the guanidino organic compound series products are amino acid substances and inorganic acid, the synthesis process is simple and controllable, the preparation process is simple, and the acid-containing washing water of the purified products can be recycled;

(3) the surface treatment fluid containing guanidyl organic compound series products does not contain chromate, phosphate, heavy metal nickel, cobalt and an additional antibacterial agent in the formula, and the formula is green and environment-friendly; the preparation process is only the mixing of multiple components, and the preparation process is simple and easy to realize;

(4) the corrosion resistance of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy prepared by the invention is similar to that of the traditional chromate conversion film, and the super-hydrophobic property is endowed to the film layer through surface modification, so that liquid and biological dirt are not easy to attach to the surface of the metal, the corrosion is prevented, and the service life of the aluminum alloy material is effectively prolonged;

(5) the invention directly realizes the antibacterial functionalization in the metal alloy surface treatment film layer, simplifies the process, and the system is all inorganic metal material, thereby avoiding the adhesion problem between the inorganic metal substrate and the organic coating;

(6) the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy prepared by the invention has excellent antibacterial performance, and the performance advantage is that the safety of consumer products such as automobile parts, locomotive surfaces, mobile phones and other electronic products and home decoration aluminum products can be improved;

(7) the method for preparing the conversion coating has simple treatment process flow, can treat the metal surface by adopting methods such as dipping, spraying, wiping and the like, has low cost, lower treatment and short treatment time, and obtains the multifunctional conversion coating on the aluminum alloy surface after being treated by certain process conditions.

The following are specific examples.

The related detection method for the synthesized guanidyl organic compound comprises the following steps:

1. nuclear magnetic resonance spectroscopy: dissolution in D was measured by Nuclear Magnetic Resonance (NMR) of Bruker AVANCE III HD, USA₂And comparing the carbon spectrum and the hydrogen spectrum of the synthesized guanidyl organic compound in O (heavy water) with the theoretical peak position to judge the purity of the synthesized product.

2. Mass spectrometry test: and (3) determining a mass spectrum of the synthesized guanidino organic compound by adopting a Finnigan LCQ Advantage Max LCMS liquid mass spectrometry ion trap mass spectrometer (LC-MS) of the U.S. Thermo company, and comparing the mass spectrum with theoretical relative molecular mass to judge the purity of the synthesized product.

3. Fourier transform infrared spectrum analysis: the synthesized guanidino organic compounds were analyzed by VERTEX70 Fourier transform infrared spectrometer (FT-IR) from Bruker, Germany, and the purity of the synthesized products was judged by comparing the peak positions of the functional groups.

The invention relates to a method for detecting an aluminum alloy conversion film layer, which comprises the following steps:

1. and (3) neutral salt spray test: the corrosion resistance of the film is judged by respectively observing the surface appearance of different conversion film neutral salt spray experiments for 300 hours by adopting a BGD882 type neutral salt spray circulating corrosion test box of Guangzhou Dageda company.

2. Scanning electron microscopy characterization: the microstructure of the conversion film on the surface of the aluminum alloy was observed by using a Scanning Electron Microscope (SEM) model XL-30 from PHILIPS, Japan.

3. Electrochemical testing: the corrosion resistance was judged by measuring the electrochemical curves of the different conversion films using electrochemical workstation CHI604D from chenhua apparatus, shanghai, respectively.

Example 1

Synthesis of guanidino organic compound 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutanoic acid

33g of asparagine was weighed and dissolved in a volume of 1L of 0.5M hydrochloric acid solution. 10.5g of cyanamide was weighed and dissolved in a 1L volume of 0.5M hydrochloric acid solution. And (3) mixing and stirring the reaction solution uniformly, then uniformly and continuously stirring and sealing the reaction solution at 5 ℃ under the condition that the pH value is 4-5, and reacting for 72 hours.

And (4) carrying out rotary evaporation on the reaction product until the reaction solvent basically disappears, filtering, washing the precipitate, completing primary crystallization, and harvesting crystals. Washing the crystal with a large amount of deionized water, adding deionized water for redissolving, performing rotary evaporation, recrystallization and filtration, washing the crystal obtained by recrystallization with a large amount of deionized water again, and drying at 104 ℃.

The nuclear magnetic resonance spectrum (NMR) of the guanidino organic compound 4-amino-2- ((hydrazinomethylimine) amino) -4-oxobutanoic acid (abbreviated AOA) obtained in example 1 is shown in FIG. 1. Wherein FIG. 1a is D₂Medium carbon spectrum in O (heavy water), measured value (δ ppm): 173.572 (-COOH); 173.557 (-CONH)₂)；158.153(-C(NH)NH₂)；52.218(-CH)；36.495(-CH₂) And theoretical value (δ ppm): 173.3 (-COOH); 172.2 (-CONH)₂)；159.5(-C(NH)NH₂)；51.2(-CH)；36.5(-CH₂) And (4) approaching. FIG. 1b is D₂In O (heavy water)Hydrogen spectrum, measured value (δ ppm): 2.535 (-NH); 2.595 (-CH)₂)；3.783(-CH)；6.665(-NH₂)；7.014(-CONH₂) (ii) a 8.006(═ NH), and theoretical values (δ ppm): 2.52 (-NH); 2.85 (-CH)₂)；3.79(-CH)；6.64(-NH₂)；7.03(-CONH₂) (ii) a 7.88(═ NH) approach. The spectrogram has no impurity peak to prove that the impurity and the by-product are few, namely the synthetic reaction product has high purity.

FIG. 2 shows a mass spectrum (LC-MS) of the reaction product obtained in example 1. As can be seen from the figure, the relative molecular mass of the reaction product was 174.16, which is consistent with the theoretical value 174 for the relative molecular mass of 4-amino-2- ((hydrazinomethylimine) amino) -4-oxobutanoic acid, confirming again that the reaction product was of high purity.

FIG. 3 shows the IR spectrum (FT-IR) of the product obtained in example 1, wherein curve a shows the product IR and curve b shows the raw material Asparagine (ASN) IR, and curve b shows 1644.5cm^-1And 1579.42cm^-1At amino group absorption peak (-NH)₂)，1236.15cm^-1Is at a C-N absorption peak of 1683.07cm^-1Is a carbonyl absorption peak at 1400.07cm^-1Is the carboxyl absorption peak at 1150.33cm^-1The absorption peak is C-O. Curve a at 3340.71cm^-1Has strong absorption peak caused by the stretching vibration of amino group at 1643.35cm^-1And 1579.7cm^-1At amino group absorption peak (-NH)₂)，1620.2cm^-1Is newly generated-C ═ N group absorption peak at 1253.73cm^-1Is at a C-N absorption peak of 1674.21cm^-1Is a carbonyl absorption peak at 1398.39cm^-1Is the carboxyl absorption peak at 1168.86cm^-1The absorption peak is C-O. Comparison of curve a and curve b shows that new C ═ N bonds are formed in the synthesized product, guanidino groups have been successfully attached to the branched amino acids of the starting asparagine, which has been fully reacted, and converted to the product 4-amino-2- ((hydrazinomethylimine) amino) -4-oxobutanoic acid.

Example 2

Weighing 8g of lithium nitrate, 1g of lithium carbonate, 1g of lithium hydroxide, 2g of sodium fluoride, 1g of sodium nitrite, 1g of simethicone, 2.8g of 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid prepared in example 1, 1g of aspartic acid, 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 1.4g of 1H,1H,2H, 2H-perfluorodecyltrimethoxysilane, dissolving the solution in 1000mL of deionized water, adjusting the pH of the solution to 10 by using nitric acid, and preparing a surface treatment solution for the lithium-aluminum hydrotalcite conversion membrane (different hydrotalcite proportions are named in Table 2).

Table 2 formula of treating solution for lithium aluminum hydrotalcite-like conversion film of example 2

Preparing a 6N01 aluminum alloy test piece, firstly manually polishing the surface of the aluminum alloy by 400 #, 800 # and 1200# abrasive paper respectively, then immersing the aluminum alloy test piece into a self-made alkaline solution formula for treatment for 5min, washing the aluminum alloy test piece by deionized water, immersing the aluminum alloy test piece into a commercially available aluminum alloy acid degreasing agent (60g/L) for treatment for 5min, washing the aluminum alloy test piece by the deionized water, immersing the aluminum alloy test piece into different treatment liquids of the prepared aluminum alloy surface lithium aluminum hydrotalcite conversion film with the temperature of 50 ℃ for 15min respectively, washing the test piece by the water, drying the test piece by cold air, drying the test piece for 20min at the temperature of 105 ℃ in a drying oven, and cooling to obtain each lithium aluminum hydrotalcite.

FIG. 4 is a SEM image of the surface morphology of AFLDHs of the lithium aluminum hydrotalcite conversion film sampled from the surface of the aluminum alloy in example 2. The observation shows that the hydrotalcite conversion film on the surface of the aluminum alloy is in a continuous sheet structure, the growth is compact and uniform, no defect exists, and the surface modification effect is good.

Fig. 5 is an electronic digital photograph showing the appearance of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy obtained from example 2 after soaking the film in a corrosive environment (3.5 wt% NaCl aqueous solution with pH 7) for 28 days. Fig. 6 is an electronic digital photograph of the appearance of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy sampled from example 2 after a neutral salt spray corrosion test for 280 hours. Wherein a is a bare aluminum alloy control group plate (bare Al), b is an empty hydrotalcite control group plate BLDHs, c is hydrotalcite ALDHs only added with 4-amino-2- ((hydrazino methyl imine) amino) -4-oxobutyric acid in the growth liquid, d is hydrotalcite FLDHs only added with a fluorine-containing organic silicon additive in the growth liquid, and e is hydrotalcite AFLDHs simultaneously added with 4-amino-2- ((hydrazino methyl imine) amino) -4-oxobutyric acid and the fluorine-containing organic silicon additive in the growth liquid. According to the observation of the graph, the hydrotalcite film layer modified by double doping of the guanidyl organic compound and the fluorosilane has stronger corrosion resistance in different corrosion environments than the single doped and modified hydrotalcite film layer, the metal surface of the aluminum alloy is more glossy, and the surface flatness of the hydrotalcite film layer is obviously better than that of an unmodified aluminum alloy bare plate.

FIGS. 7 to 11 are graphs comparing the electrochemical AC impedance of the aluminum alloy surface Li-Al hydrotalcite conversion film obtained from the sample in example 2 after soaking in a corrosive environment (3.5 wt% NaCl solution with pH 7) for different days, and the electrochemical impedance spectrum circuit is simulated by Zsimpwin software, with the abscissa Z_ReIs the real part of the electrochemical impedance value, ordinate Z_ImThe imaginary part of the electrochemical impedance value, in ohms (Ω). The impedance value of the hydrotalcite film layer modified by double doping of a guanidyl organic compound and fluorosilane is 3.453 multiplied by 10 on the first day⁵Ω·cm^-2After 20 days of soaking and corrosion, the corrosion rate is reduced to 2.827 multiplied by 10⁵Ω·cm^-2The initial impedance value is higher than that of other singly doped/undoped modified hydrotalcite plates and bare aluminum alloy plates, the numerical value of the impedance value reduction in each test is lower than that of other control plates, and the electrochemical tracking test in the corrosion process proves that the corrosion resistance of the aluminum alloy is greatly improved after the surface lithium aluminum hydrotalcite conversion film is modified.

Example 3

In the general formula, R is CH₂CHO、CH₂COOH or CH₂COOCH₂Respectively replacing the 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid prepared in the example 1, and preparing a lithium-aluminum hydrotalcite conversion membrane by the same process as the example 2 and other steps.

FIG. 12 is a comparison graph of electrochemical AC impedance of a lithium aluminum hydrotalcite conversion film on the surface of an aluminum alloy modified by corrosion inhibitors with different R groups in a corrosive environment (3.5 wt% NaCl aqueous solution with pH 7), and a Zsimpwin software is used to simulate an electrochemical impedance spectroscopy circuit, which shows that when R is CH₂CONH₂When the temperature of the water is higher than the set temperature,the impedance value is 3.45 multiplied by 10⁵Ω·cm^-2Is obviously better than R ═ CH₂Resistance value of COOH (2.52X 10)⁵Ω·cm^-2) Is also obviously better than R ═ CH₂CHO or CH₂COOCH₂The case (1). In addition, when R ═ CH₂CH₂CONH₂In addition, the synthesized corrosion inhibitor also has high corrosion resistance, and the prepared modified hydrotalcite film also has high electrochemical resistance value.

Example 4

6g of lithium nitrate, 1.2g of lithium sulfate, 1.2g of lithium phosphate, 1.2g of lithium hydroxide, 0.6g of sodium nitrate, 0.4g of sodium nitrite, 0.4g of trisodium phosphate, 0.5g of asparagine or 0.5g of aspartic acid, 0.5g of arginine, 2g of 4-amino-2- ((hydrazinomethylimine) amino) -4-oxobutyric acid prepared in example 1 or 2g of guanidinosuccinic acid (i.e. R ═ CH ═ is weighed₂COOH), 0.6g of 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 0.6g of 1H,1H,2H, 2H-perfluorodecyltrimethoxysilane, 0.4g of 1H,1H,2H, 2H-perfluoroheptadecyltrimethyloxysilane, and 0.4g of trichloro (1H,1H,2H, 2H-perfluorooctyl) silane, wherein the solutions are dissolved by 1000mL of deionized water, and the pH of the solutions is adjusted to 10 by nitric acid, thereby preparing a treatment solution for a lithium-aluminum hydrotalcite-like conversion membrane.

Preparing a 6N01 aluminum alloy test piece, firstly, manually polishing the surface of the aluminum alloy by using 400, 800 and 1200# abrasive paper respectively, then, putting the aluminum alloy test piece into a self-made alkaline solution formula (20 g/L of sodium hydroxide and 6g/L of white cat washing powder) for treatment for 3min, washing the aluminum alloy test piece by using deionized water, then, immersing the aluminum alloy test piece into an aluminum alloy acid degreasing agent (60g/L of 63% nitric acid) for treatment for 3min, washing the aluminum alloy test piece by using the deionized water, immersing the aluminum alloy test piece into the prepared treatment working solution of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy at the temperature of 60 ℃ for treatment for 20min, washing the test piece by using cold air for blow-drying, drying the test piece for 15min at the temperature of 102 ℃.

FIG. 13 is an electronic digital photograph showing the planar water contact angle of the lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy modified by the treatment solution prepared from 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid of example 1, which shows that the surface of the aluminum alloy is hydrophobically modified to have a water contact angle as high as 151.2 degrees and solvent adhesion resistanceAnd resistance to staining. FIG. 14 is a guanidinosuccinic acid (i.e., R ═ CH)₂COOH) to obtain the treatment fluid modified aluminum alloy surface lithium aluminum hydrotalcite conversion film plane water contact angle electronic digital photo, the water contact angle is reduced to 139.3 degrees, and the anti-solvent adhesion and anti-contamination capability is reduced.

Fig. 15 is an electronic digital photograph of droplets of water (water), oil drops (oil), milk (milk), tea (tea), red wine (red wine) and soil solution (soil solution) on the surface of a lithium aluminum hydrotalcite conversion film on the surface of an aluminum alloy, which is obtained by modifying a treatment solution prepared from 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid and sampled, so that it can be known that the surface of the aluminum alloy is resistant to various solvents after surface hydrophobic modification, which has an important help effect on assisting in improving the anti-bioadhesion and anti-contamination capability of the metal surface.

Example 5

Weighing 8.2g of lithium nitrate, 2.2g of lithium hydroxide, 3g of sodium fluoride, 1g of sodium nitrate, 0.8g of guanidinoacetic acid, 3g of 4-amino-2- ((hydrazinomethyl imine) amino) -4-oxobutyric acid, 0.8g of 1H,1H,2H, 2H-perfluorooctyltriethoxysilane, 0.8g of 1H,1H,2H, 2H-perfluorodecyltrimethoxysilane, 0.8g of 1H,1H,2H, 2H-perfluoroheptadecyltrimethyloxysilane, and dissolving by using 1000mL of deionized water to prepare the treating fluid of the lithium-aluminum hydrotalcite conversion membrane (different hydrotalcite proportions are named in Table 3).

Table 3 formula of treating solution for lithium aluminum hydrotalcite-like conversion film of example 5

Preparing a 6N01 aluminum alloy test piece, firstly manually polishing the surface of the aluminum alloy by 400 #, 800 # and 1200# abrasive paper respectively, then processing the aluminum alloy test piece in a self-made alkaline solution formula for 4min, washing the aluminum alloy test piece by deionized water, then soaking the aluminum alloy test piece in a commercially available RS-228 acid degreasing agent (60g/L) for 4min, washing the aluminum alloy test piece by the deionized water, soaking the aluminum alloy test piece in the prepared processing working solution of the self-repairing lithium aluminum hydrotalcite conversion film on the surface of the aluminum alloy at the temperature of 55 ℃ for 22min, drying the test piece by cold air after washing the test piece, drying the test piece for 22min at the temperature of 102 ℃ in a drying oven, and cooling to obtain the lithium aluminum hydrotalcite conversion film.

Coating and inoculating Escherichia Coli (EC), Bacillus Subtilis (BS) and Sulfate Reducing Bacteria (SRB) on the surface of a hydrotalcite film in a sterile super clean bench, respectively incubating for 2 hours in a strain growth environment, fixing and spraying gold, and then taking a high-power Scanning Electron Microscope (SEM) picture, or incubating for 48 hours in the strain growth environment, fixing and taking an optical microscope digital picture bacterial colony picture.

FIGS. 16 to 17 are a digital photograph and a high-power scanning electron microscope SEM photograph (a) of colonies of Escherichia Coli (EC), Bacillus Subtilis (BS) and sulfate-reducing bacteria (SRB) resistant lithium aluminum hydrotalcite conversion films on the surfaces of the sampled aluminum alloys₁、b₁、c₁Corresponding to BLDHs, a₂、b₂、c₂Corresponding to ALDHs, a₃、b₃、c₃Corresponding to FLDHs, a₄、b₄、c₄Corresponding to AFLDHs, a₅、b₅、c₅Corresponding magnified view of AFLDHs). With the addition of the corrosion inhibitor and the fluorosilane, the capacities of the conversion film for resisting gram-negative bacteria (escherichia coli), gram-positive bacteria (bacillus subtilis) and anaerobic bacteria (sulfate reducing bacteria) are gradually improved, and the capacities of resisting biological adhesion and corrosion scaling are gradually enhanced. In summary, the performance of the different samples in this example is summarized in table 4.

TABLE 4 comparison table of properties of lithium aluminum hydrotalcite-like conversion film

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.