CN102199390B - Protective agent for bridge with steel structure, preparation method thereof and application thereof - Google Patents

Abstract

The invention discloses a protective agent for a bridge with a steel structure, a preparation method thereof and application thereof. The protective agent comprises the following components: an organic/inorganic composite fluorosilicone styrene polymer, lithium silicate, sodium molybdate, benzotriazole, nanometer titanium dioxide, sodium gluconate, ethanolamine, absolute ethanol and distilled water. Corrosion inhibiting ingredients contained in the protective agent can be attached to the metal surface of the bridge with the steel structure, so that a compact protective film is formed on the metal surface due to a passivating reaction for corrosion inhibition and corrosion prevention; a low-surface energy fluorosilicone styrene polymer component contained in the protective agent can be cured to form a film for playing the hydrophobic and protective roles; a nanometer component can improve the performance of ultraviolet aging resistance of a film layer, improve the performance of the polymer and provide the excellent self-cleaning performance and the like for the cured film; and hydroxyl generated by hydrolyzing siloxane groups can perform a condensation reaction with hydroxyl on the surface of the bridge with the steel structure to generate a chemical bond so as to improve adhesive power between the film layer and a matrix material and improve interface bonding. The protective agent is high in stability, non-toxic, environment-friendly, multiple in functions and easy to construct, can be widely used for the protection of the structural engineering of various bridges with the steel structures, and is favorable for improving the service life of the bridge with the steel structure.

Description

A kind of protective agent for steel structure bridge and its preparation and application method

technical field

The invention relates to a protective agent for a steel structure bridge, in particular to a water-based protective agent capable of improving the service life of a steel structure bridge and a preparation and application method thereof.

Background technique

Steel bridges are widely used due to their advantages of large span, strong bearing capacity and short construction period. Bridges are mainly built in high-humidity environments such as across rivers and bays. External corrosive substances (such as chloride salts, acid rain, and sulfates, etc.) can easily condense and accumulate on the surface of steel structure bridges along with water vapor, which can easily cause steel structure bridges. Corrosion damage. At the same time, under the interaction of physical and chemical factors such as salt spray, acid rain, freezing, rain, snow and light in the natural environment, steel bridges are prone to performance degradation and damage. How to reduce the destructive effect of external physical and chemical factors on steel bridges is one of the important measures to improve the service life of bridges. At present, surface protection measures are often used for steel bridges at home and abroad to reduce the impact of external environmental factors on bridge structures. The surface protection can buffer the effects of external loads, temperature fields, and humidity fields on the bridge, effectively reducing the intrusion of external water, carbon dioxide, and chloride ions, thereby reducing erosion damage caused by various erosion effects. A large number of studies and engineering practices have shown that one of the most commonly used and effective protective measures is the use of surface protective agents.

Surface protective agents are mostly made of inorganic materials, organic materials, and a combination of the two. Commonly used inorganic materials are mostly components with antirust function (such as nitrite, phosphate and dichromate, etc.), active metal powder (such as zinc powder and aluminum powder, etc.) and a certain amount of gelling material. Or the organic matter is mixed and coated on the surface of the steel structure bridge to achieve the effect of isolating the outside world and inhibiting corrosion; while the organic materials are mostly resin (such as polyurethane and epoxy resin, etc.), asphalt, organic coatings, paints and polyol esters, etc. Direct coating On the surface of the steel structure bridge, it plays the role of protection and rust prevention. Inorganic materials have the advantages of anti-aging, stability, durability and environmental protection, but they often face problems such as single function and poor adhesion; Effects are prohibited (such as nitrite, etc.). Organic materials have the advantages of multiple functions, high efficiency and easy construction, but they are prone to aging, cracking, pulverization and poor weather resistance, and have relatively large environmental negative effects. The shortage of these two types of materials makes it difficult to prepare a single type of protective agent to meet the needs of the project. How to give full play to the respective advantages of inorganic and organic materials is a hot and difficult point in the field of metal protection today. Among them, the development of organic/inorganic composite protective agent is an effective way.

Some metal protective agents researched and developed today focus on single performance protection (such as anti-corrosion, protection, etc.), and tend to ignore the multifunctional requirements in metal protection. For example, an invention patent named "Permanent protective agent for ferrous metals and its production method" (authorized announcement number CN 101139496B) is characterized in that it uses phenolic resin, polyvinyl butyral and polyvinyl formal as the main body to form a film. Liquid, react with aluminum naphthenate in a reactor to produce a translucent liquid product. The mechanism of action of this invention is to rely on blocking the contact between external substances and metals to achieve a protective effect; if the protective film layer is damaged, external water and corrosive substances and other easy-to-contact metals will cause corrosion reactions, thereby reducing the protective effect. An invention patent named "a protective agent composition" (Patent No. 93103720.4), which is characterized by benzotriazole, triethanolamine and sodium molybdate, etc., and its mechanism of action is to form a layer on the metal surface The dense passivation film reduces the contact between the external corrosive medium and the metal, thereby improving the anti-corrosion performance of the metal. From the existing protective agents and their application effects, it is difficult to ensure that steel bridges will not be damaged by corrosion by using a protective agent with a single performance. Therefore, the development of a compound protective agent with the functions of insulation protection and rust inhibition can meet the needs of the project to a certain extent, and has good economic and environmental benefits.

Contents of the invention

The object of the present invention is to make up for the deficiencies of the above-mentioned prior art, and provide a protective agent with functions of protection and rust prevention to increase the service life of steel bridges.

Another object of the present invention is to provide the preparation and application method of the protective agent.

The invention is an organic-inorganic composite protective agent prepared by compounding the synthesized organic/inorganic composite fluorosilicone styrene-acrylic polymer and antirust components. In the present invention, organic polymers with hydrophobic and protective functions are used to solidify and form films to isolate the steel structure bridge from contact with the outside world and reduce the erosion of the steel structure bridge by the external medium; the antirust component is easily absorbed by the metal on the surface, so that the metal structure The passivation reaction forms a dense oxide film layer to improve the anti-corrosion ability of the metal; the nano-components and light stabilizers contained in it endow the protective agent with good anti-aging ability and stability. In addition, the contained siloxane groups are hydrolyzed to generate hydroxyl groups, which can undergo condensation reaction with the hydroxyl groups on the surface of the steel structure bridge to form chemical bonds, and improve the adhesion between the film layer and the steel structure bridge.

The present invention is mainly achieved through the following technical solutions:

A steel bridge protective agent, which is prepared from the following components by weight:

Organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion with a solid content of 20-40% 40-100;

Benzotriazole 0.3-0.9; Lithium silicate 0.6-1.2;

Sodium molybdate 0.03-0.3; Sodium gluconate 0.05-0.8;

Ethanolamine 1.5-8; Sodium tetraborate 0.02-0.1;

Nano titanium dioxide 0.01-0.08; absolute ethanol 0.5-4;

Distilled water 0-60.

Prepare the preferred proportioning range by parts by weight of the present invention:

Organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion with a solid content of 20-40% 60-90;

Benzotriazole 0.5-0.9; Lithium silicate 0.6-1;

Sodium molybdate 0.05-0.2; Sodium gluconate 0.2-0.8;

Ethanolamine 2-6; Sodium tetraborate 0.05-0.08;

Nano titanium dioxide 0.03-0.06; Absolute ethanol 1-3;

Distilled water 10-40.

The best proportioning in parts by weight of the present invention is:

Organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion with a solid content of 25% 80;

Benzotriazole 0.7; Lithium silicate 0.8;

Sodium molybdate 0.1; Sodium gluconate 0.6;

Ethanolamine 5; Sodium Tetraborate 0.06;

Nano titanium dioxide 0.04; absolute ethanol 1;

Distilled water 20.

The ethanolamine includes one or a mixture of diethanolamine and triethanolamine.

The nano-titanium dioxide is anatase or nano-titanium dioxide mixed crystal mainly composed of anatase.

The organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion is prepared by semi-continuous emulsion polymerization, and the raw materials used include the following components by weight:

Fluoride monomer 20-60;

Siloxane monomer 3-12;

Hydrosol 15-35 of surface-modified inorganic nanomaterials with a mass content of 15-30%;

Methyl methacrylate 10-30;

Styrene 10-30;

Butyl acrylate 10-55;

Hydroxyethyl methacrylate 2-10;

Methacrylic acid 2-10;

Emulsifier 2.5-8;

Initiator 0.5-2;

Distilled water 270-290.

When the described organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion has the best performance, the raw materials used include the following components by weight:

Fluoride monomer 35; Siloxane monomer 8

Surface-modified inorganic nanomaterial hydrosol with a mass content of 20% 30;

Methyl methacrylate 15; Styrene 15

Emulsifier 3.6; Butyl acrylate 18;

Methacrylic acid 5; Hydroxyethyl methacrylate 5;

Initiator 1; Distilled water 280.

The inorganic nanomaterial in the surface-modified inorganic nanomaterial hydrosol contains one or more mixtures of three oxides of SiO ₂ , Al ₂ O ₃ and TiO ₂ .

The fluoride monomer includes hexafluorobutyl methacrylate; dodecafluoroheptyl acrylate; one or more mixtures of trifluorooctyl acrylate; the siloxane monomer includes methacryloyl One or a mixture of oxypropyltrimethoxysilane, aminopropyltriethoxysilane and glycidoxymethyltrimethoxysilane.

The initiator is one or a mixture of potassium persulfate and ammonium persulfate; the emulsifier is octylphenol polyoxyethylene (10) ether and allyl nonylphenol polyoxyethylene ammonium sulfonate one or a mixture of both.

The hydrosol of the surface-modified inorganic nanomaterials adopts the sol-gel method, and the molar ratio of organic alkoxide, absolute ethanol, distilled water and ammonia water is 1: (15-50): (1-3): (0.06-0.15) reaction to obtain the alcohol sol of the inorganic nanometer material, then modify the surface of the siloxane monomer, and replace the alcohol solvent with water. The organic alkoxide includes one or a mixture of tetraethyl silicate, butyl titanate and aluminum isopropoxide. The siloxane monomer includes one or a mixture of methacryloxypropyltrimethoxysilane, aminopropyltriethoxysilane and glycidoxymethyltrimethoxysilane The dosage thereof is 10-40% of the total weight of nano-oxides in the alcohol solution of inorganic nano-materials.

The active ingredient of the organic/inorganic composite fluorosilicone-acrylic polymer emulsion is latex particles with a surface-modified inorganic nanometer material as the core and an organic polymer as the shell.

The surface-modified inorganic nanomaterials constituting the core include one or a mixture of three oxides of SiO ₂ , Al ₂ O ₃ and TiO ₂ , and silicon attached to its surface for modification. oxane monomer.

The organic polymer constituting the shell includes: fluoride monomer, siloxane monomer, methyl methacrylate, butyl acrylate, styrene, methacrylic acid and hydroxyethyl methacrylate.

The hydrosol of the surface-modified inorganic nano-material is to concentrate the above-mentioned alcohol sol containing the surface-modified inorganic nano-material prepared by the sol-gel method in a vacuum, and use a small amount of distilled water to replace the non-aqueous sol for subsequent polymerization. obtained from water and ethanol; its mass content of 15-30% also refers to the mass percentage of the surface-modified inorganic nanometer material in the hydrosol.

The preparation method of described steel structure bridge protective agent, comprises the following steps:

1) Preparation of organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion

The use of fluoride monomers, siloxane monomers, methyl methacrylate, styrene, butyl acrylate, methacrylic acid, hydroxyethyl methacrylate, emulsifiers, initiators, surface-modified inorganic nanomaterials Hydrosol, prepared by semi-continuous emulsion polymerization;

2) dissolving benzotriazole in absolute ethanol to form an alcoholic solution;

3) The solutions obtained in steps 1) and 2), lithium silicate, sodium molybdate, sodium gluconate, nano-titanium dioxide, sodium tetraborate and ethanolamine are added with water and stirred to obtain a steel bridge protective agent.

The preparation method of the above-mentioned steel bridge protective agent is as follows:

The first step: preparation of inorganic nanomaterials and surface modification thereof by hydrolysis of organic alcohol salts, the preparation method is as follows:

A. Dissolve the organic alkoxide in a certain amount of absolute ethanol, mix well and put it into a separatory funnel for later use;

B. Add absolute ethanol, distilled water and ammonia water into a four-necked flask equipped with a reflux condensing device and an electric stirrer in a certain ratio, stir at a speed of 100-300 rpm for 1-4 hours, mix well and then slowly heat up ;

C. When the temperature rises to 45-60°C, drop the mixture in the separatory funnel into the four-necked flask, stir rapidly at a speed of 150-300 rpm, and react for 1-6 hours;

D, stirring and aging at room temperature for 12-48 hours to obtain the desired alcohol sol of inorganic nanomaterials;

E. Under low-speed stirring conditions, add a certain amount of siloxane monomer dropwise into the alcohol sol of inorganic nanomaterials, react at room temperature for 12-24 hours, raise the temperature to 40-60°C and react at constant temperature for 1-5 hours, that is Obtain the alcohol sol of the surface-modified inorganic nanomaterial;

F. Concentrating the alcohol sol of the surface-modified inorganic nanomaterial by vacuum drying, and replacing it with a certain amount of water to obtain the hydrosol of the surface-modified inorganic nanomaterial.

The second step: adopt emulsion polymerization to synthesize organic-inorganic composite polymer, and its preparation method is as follows:

A. Prepare a stable monomer pre-emulsion with an emulsifier accounting for 1-4% of the monomer mass and water equal in mass to the monomer; each monomer includes: methyl methacrylate, styrene, butyl acrylate, Hydroxyethyl Methacrylate, Methacrylic Acid, Fluoride Monomer, Silicone Monomer.

B. Add the hydroalcoholic sol of surface-modified inorganic nanomaterials in a four-neck flask equipped with stirring, reflux condenser, and thermometer, and add part of emulsifier, distilled water and sodium bicarbonate, at a speed of 200-300 rpm Stir at a high speed, mix evenly and heat up;

C. When the temperature rises to 70-85°C, drop part of the pre-emulsified aqueous solution of methyl methacrylate and a small amount of styrene into the flask, and simultaneously drop part of the initiator solution, and react for 0.5-2 hours; Raise the temperature to 75-90°C, add dropwise the five monomer pre-emulsified aqueous solutions of hydroxyethyl methacrylate, the remaining methyl methacrylate, part of butyl acrylate, the remaining styrene and methacrylic acid, and drop them simultaneously Part of the initiator solution, react at constant temperature for 0.5-1 hour; continuously drop the pre-emulsified aqueous solution of the three monomers of fluoride monomer, siloxane monomer and the remaining butyl acrylate, and simultaneously add the remaining initiator solution dropwise, keep the temperature constant React for 4-12 hours, lower the temperature to below 40°C, adjust the pH value to neutral, and obtain an organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion; take about 5g of the emulsion and put it into a petri dish with a weight of m ₀ , and weigh it as m ₁ ; dry it in an oven at 105±5°C to constant weight, take it out and put it in a desiccator to cool to room temperature and weigh it as m ₂ ; the solid content W of the synthesized polymer emulsion is calculated according to the following formula:

$\mathrm{<span\; class="notranslate">\; W</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; \%</span>$

Step 3: Dissolve benzotriazole in a small amount of absolute ethanol to form an alcoholic solution;

The fourth step: Add the solutions obtained in the second and third steps, lithium silicate, nano-titanium dioxide, sodium molybdate, sodium gluconate, ethanolamine and sodium tetraborate in proportion to the reactor containing a certain amount of distilled water , and mix evenly at a speed of 100-150 rpm at room temperature to obtain a steel structure bridge protective agent.

In the present invention, the organic/inorganic composite fluorosilicone styrene-acrylic polymer can be cured to form a film on the surface of the steel structure bridge. The impact of steel bridges. During the curing process of the fluorosilane component with low surface energy, it can endow the film with good hydrophobic properties. Inorganic nanomaterials can not only improve the performance of the polymer and increase the good roughness of the film, but also endow the film with anti-ultraviolet aging and self-sufficiency. cleanliness etc. In addition, the contained siloxane groups are hydrolyzed to generate hydroxyl groups, which can undergo condensation reaction with the hydroxyl groups on the surface of the steel structure bridge to form chemical bonds, and improve the adhesion between the film layer and the steel structure bridge.

Benzotriazole is an organic polymer light stabilizer, metal antirust agent and corrosion inhibitor with excellent performance. It has good ultraviolet light absorption ability, which can endow the polymer with good anti-aging performance; it can form covalent bonds and coordination bonds with metal atoms, and alternately form chain polymers to form a protective film on the metal surface to prevent redox reactions caused rust. In addition, when it is used in conjunction with a variety of corrosion inhibitors, the corrosion inhibition effect is better.

Lithium silicate, as a surface treatment agent and antirust agent, can react with metals and their surface hydroxyl groups to form Fe ₂ (SiO ₃ ) ₃ and other silicate film layers, which are heat-resistant, non-combustible, radiation-resistant, and color-retaining , non-toxic, self-drying and resistance to alternating wet and dry. In addition, some lithium ions are adsorbed on the surface of the steel bar to passivate and protect the steel.

Sodium molybdate is an effective pitting corrosion inhibitor, which can significantly enhance the pitting resistance of metals, and react with iron to form Fe(MoO ₃ ) ₃ , which can repassivate and seal pitting corrosion. When used in combination with polyphosphate, gluconate, zinc salt and benzotriazole, it can not only reduce the amount of rust inhibitor used, but also have a better corrosion inhibition effect.

Sodium gluconate is a corrosion inhibitor and chelating agent. It has obvious coordination effect and is suitable for compounding with molybdenum, silicon, phosphorus, tungsten and nitrite, etc., which can improve the corrosion inhibition effect; compared with general corrosion inhibitors, the corrosion inhibition rate increases with the increase of temperature ; It has strong complexing ability for calcium, magnesium and iron salts, especially for Fe ³⁺ , which can effectively reduce the external corrosion of iron.

Ethanolamine has corrosion inhibition and chelating effects. It can be chelated with a variety of heavy metals to form stable chelates with 2-4 coordinations. It is an excellent chelating agent; as a corrosion inhibitor, it can prevent the oxidation of metal surfaces, thereby improving the corrosion resistance of steel bridge metals.

Sodium tetraborate has a certain corrosion inhibition function, and can be used in coordination with molybdate, silicate and gluconate, etc., and has a good corrosion inhibition effect.

Water acts as a solvent to uniformly disperse, which is beneficial to construction and has no negative environmental effects.

The steel structure bridge protective agent of the present invention is a liquid, which can be coated on the surface of the steel structure bridge.

The beneficial effects of the present invention are:

1. Use surface modification and emulsion polymerization to combine organic and inorganic materials in the form of chemical bonds, thereby modifying organic polymers, effectively reducing the peeling between organic/inorganic materials, and inhibiting the excessive growth of polymers when they solidify into films. Shrinkage overcomes the instability and phase separation caused by different materials, gives full play to the advantages of inorganic and organic materials, and realizes the complementary advantages of different materials.

2. The fluorosilane component contained in the organic/inorganic composite fluorosilicone styrene-acrylic polymer itself has good hydrophobicity and anti-aging properties. Curing and forming a film can reduce the contact of external water and harmful media with metals; inorganic nanomaterials have good synergy The function can effectively improve the roughness of the cured film and increase the hydrophobicity of the film layer; the light stabilizer and nano-components can give the cured film good anti-ultraviolet aging and self-cleaning properties; the anti-rust components contained are non-toxic, efficient Compounded with various organic/inorganic rust inhibitors and corrosion inhibitors with good weather resistance, they have a good coordination effect with each other, and are easily adsorbed on the metal surface to passivate them, thereby reducing the metal corrosion rate.

3. The contained siloxane groups are hydrolyzed to form hydroxyl groups, which can undergo condensation reaction with the hydroxyl groups on the surface of the steel structure bridge to form chemical bonds, improve the adhesion between the protective agent and the substrate, and avoid falling off and drumming during use.

4. The synthesis uses water and a small amount of ethanol as solvents, and its cost is low and no toxic by-products are produced; in the process of use, relying on the characteristics of each component of the protective agent to endow it with multifunctionality, it has good environmental benefits.

Description of drawings

Figure 1 is a TEM image of the organic/inorganic composite fluorosilicone styrene-acrylic polymer microspheres synthesized in Examples 1, 2 and 3.

Detailed ways

The following examples are further descriptions of the technical content of the present invention, but not limitations to the essential content of the present invention.

Example 1:

Mix 0.1 kg of aluminum isopropoxide, 0.3 kg of butyl titanate, 1.7 kg of tetraethyl silicate, and 6 kg of absolute ethanol for use; mix 10 kg of absolute ethanol, 0.4 kg of distilled water, and 0.1 kg of ammonia water ( The mass fraction is 25%) into a reactor equipped with a reflux condensing device and an electric stirrer, stirred at a speed of 150 rpm for 1-2 hours, mixed uniformly and then slowly heated up; when the temperature rose to 45-60°C, Add the organic alkoxide and ethanol mixture dropwise into the reactor, stir rapidly at a speed of 200 rpm, and react for 2-4 hours; stir and age at room temperature for 24 hours to obtain the desired alcohol sol of the inorganic nanomaterial. Under the condition of low-speed stirring, add 0.18 kg of methacryloxypropyltrimethoxysilane dropwise into the alcohol sol of inorganic nanomaterials, react at room temperature for 22 hours, raise the temperature to 50°C and react at constant temperature for 2 hours, and the surface modified Alcohol sol of non-toxic inorganic nanomaterials; concentrated by vacuum drying method, and adding 2 kg of water instead of ethanol to obtain the hydrosol of surface-modified inorganic nanomaterials.

Add 3 kilograms of hydrosol (mass fraction is about 20%) of the surface-modified inorganic nanometer material in the reactor equipped with stirring, reflux condenser, thermometer, and add octylphenol polyoxyethylene (10) ether 0.01 kg, 0.01 kg of allyl nonylphenol polyoxyethylene sulfonate ammonium, 16 kg of distilled water and 0.012 kg of pH adjusting buffer sodium bicarbonate, and nitrogen gas was passed into it for 1 hour to remove the air; then, stirred at a speed of 200 rpm Uniform and heat up; when the temperature rises to 75 ° C, 0.6 kg of methyl methacrylate, 0.7 kg of styrene, 1.3 kg of water, 0.015 kg of octylphenol polyoxyethylene (10) ether and allyl nonylphenol Add the pre-emulsion prepared by 0.015 kg of polyoxyethylene sulfonate ammonium into the reactor, and synchronously dropwise add 0.26 kg of potassium persulfate solution (the mass fraction is 5%), and react for 0.5 hour; 1.2 kg, 0.5 kg of hydroxyethyl methacrylate, 0.5 kg of methacrylic acid, 0.9 kg of methyl methacrylate, 0.8 kg of styrene, 3.9 kg of water, 0.065 kg of octylphenol polyoxyethylene (10) ether and alkene The pre-emulsion made by 0.065 kg of propyl nonylphenol polyoxyethylene sulfonate ammonium was added in the reactor, and 0.76 kg of potassium persulfate solution was added dropwise synchronously (the mass fraction was 5%), and the constant temperature was reacted for 0.5 hour; 0.6 kg of ester, 1.75 kg of hexafluorobutyl methacrylate, 1.75 kg of dodecafluoroheptyl acrylate, 0.8 kg of methacryloxypropyl trimethoxysilane, 4.9 kg of water, octylphenol polyoxyethylene ( 10) Add 0.09 kg of ether and 0.09 kg of allyl nonylphenol polyoxyethylene sulfonate ammonium pre-emulsion to the reactor, and simultaneously dropwise add 0.98 kg of potassium persulfate solution (mass fraction is 5%), keep the temperature React for 5 hours, lower the temperature to below 40°C, adjust the pH value to neutral with ammonia water (25% by mass fraction), and obtain a stable organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion (solid content is about 25%).

Add 60 kg of organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion and 40 kg of distilled water into a mixer with a stirrer, and mix evenly at a speed of 100 rpm; heat up to 40±5°C, and lithium silicate 0.6 kg, 0.1 kg of sodium molybdate, 0.3 kg of benzotriazole and 0.6 kg of anhydrous ethanol, 0.2 kg of sodium gluconate, 0.03 nano-titanium dioxide, 1.5 kg of ethanolamine and 0.05 kg of sodium tetraborate are slowly added to the mixer in turn and stir for 2-6 hours to obtain the protective agent for steel structure bridges.

Example 2:

The organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion was prepared as in Example 1.

Add 80 kg of organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion and 20 kg of distilled water into a mixer with a stirrer, and mix evenly at a speed of 100 rpm; heat up to 40±5°C, and lithium silicate 0.8 kg, 0.1 kg of sodium molybdate, 0.7 kg of benzotriazole and 1 kg of absolute ethanol, 0.6 kg of sodium gluconate, 0.04 nanometer titanium dioxide, 5 kg of ethanolamine and 0.06 kg of sodium tetraborate are slowly added to the mixer in turn and stir for 2-6 hours to obtain the protective agent for steel structure bridges.

Example 3:

The organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion was prepared as in Example 1.

Add 70 kg of organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion and 30 kg of water into a mixer with a stirrer, and mix evenly at a speed of 100 rpm; heat up to 40±5°C, and lithium silicate 0.8 kg, 0.12 kg of sodium molybdate, 0.6 kg of benzotriazole and 1 kg of absolute ethanol, 0.5 kg of sodium gluconate, 0.05 kg of nano-titanium dioxide, 3 kg of ethanolamine and 0.06 kg of sodium tetraborate are slowly added to the mixer in turn and stir for 2-6 hours to obtain the protective agent for steel structure bridges.

Example 4:

The synthetic preparation of the steel bridge protective agent is the same as in Example 2, but the raw materials used for the synthetic fluorosilicone styrene-acrylic polymer emulsion with a solid content of about 20% are as follows:

Fluoride monomer 22; Siloxane monomer 4;

Surface-modified inorganic nanomaterials (mass fraction is 20%) 10;

Emulsifier 2.5; Styrene 11;

Methyl methacrylate 11; Butyl acrylate 18;

Methacrylic acid 2; Hydroxyethyl methacrylate 2;

Initiator 1; Distilled water 270.

Example 5:

The synthetic preparation of the steel bridge protective agent is the same as in Example 2, but the raw materials used for the synthetic solid content of about 35% have/inorganic composite fluorosilicone-acrylic polymer emulsion are as follows:

Fluoride monomer 55; Siloxane monomer 10;

Surface-modified inorganic nanomaterials (mass fraction is 20%) 30;

Emulsifier 4.5; Styrene 22;

Methyl methacrylate 22; Butyl acrylate 38;

Methacrylic acid 6; Hydroxyethyl methacrylate 6;

Initiator 1.3; Distilled water 270.

Embodiment 6:

The synthetic preparation of the steel bridge protective agent is the same as in Example 2, but the raw materials used for the synthetic solid content of about 30% organic/inorganic composite fluorosilicone acrylic polymer emulsion are as follows:

Fluoride monomer 25; Siloxane monomer 5;

Surface-modified inorganic nanomaterials (mass fraction is 20%) 20;

Emulsifier 3; Styrene 27;

Methyl methacrylate 28; Butyl acrylate 35;

Methacrylic acid 5; Hydroxyethyl methacrylate 5;

Initiator 1.2; Distilled water 280.

The TEM image of the above-mentioned organic/inorganic composite fluorosilicone styrene-acrylic polymer microspheres is shown in FIG. 1 . It can be seen from the figure that the synthesized microsphere particles have a core composed of inorganic nanomaterials and a shell structure composed of organic polymers, which can endow the organic polymer emulsion particles with better weather resistance, heat resistance, and aging resistance and other mechanical properties.

The performance test of the prepared steel bridge protective agent is shown in the following table:

Claims (7)

1. A protective agent for steel bridges is characterized in that it is prepared from the following components in parts by weight: Organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion with a solid content of 20-40% 40-100; Benzotriazole 0.3-0.9; Lithium silicate 0.6-1.2; Sodium molybdate 0.03-0.3; Sodium gluconate 0.05-0.8; Ethanolamine 1.5-8; Sodium tetraborate 0.02-0.1; Nano titanium dioxide 0.01-0.08; Absolute ethanol 0.5-4; Distilled water 0-60; The organic/inorganic composite fluorosilicone styrene-acrylic polymer is prepared by semi-continuous emulsion polymerization, and the raw materials used include the following components by weight: Fluoride monomer 20-60; Siloxane monomer 3-12; Hydrosol 15-35 of surface-modified inorganic nanomaterials with a mass content of 15-30%; Methyl methacrylate 10-30; Styrene 10-30; Butyl acrylate 10-55; Hydroxyethyl methacrylate 2-10; Methacrylic acid 2-10; Emulsifier 2.5-8; Initiator 0.5-2; Distilled water 270-290; The surface-modified inorganic nanomaterials include one or a mixture of three oxides of SiO ₂ , Al ₂ O ₃ and TiO ₂ ; The hydrosol of the surface-modified inorganic nanomaterial adopts the sol-gel method, and the molar ratio of organic alkoxide, dehydrated alcohol, distilled water and ammonia water is 1:(15-50):(1-3): (0.06-0.15) reaction to obtain the alcohol sol of the inorganic nanometer material, then modify the surface of the siloxane monomer, and replace the alcohol solvent with water. 2. The protective agent for steel bridges according to claim 1, wherein the fluoride monomer comprises one of hexafluorobutyl methacrylate; dodecafluoroheptyl acrylate; tridecafluorooctyl acrylate or a mixture of several; the siloxane monomer includes one of methacryloxypropyltrimethoxysilane, aminopropyltriethoxysilane and glycidoxymethyltrimethoxysilane species or a mixture of several species. 3. steel bridge protective agent according to claim 1, is characterized in that described initiator is one or both mixtures in potassium persulfate and ammonium persulfate; Described emulsifier is octylphenol polyoxyethylene One or a mixture of alkane (10) ether and allyl nonylphenol polyoxyethylene sulfonate ammonium. 4. The protective agent for steel bridges according to claim 1, characterized in that said organic alkoxide comprises one or a mixture of tetraethyl silicate, butyl titanate and aluminum isopropoxide. 5. The steel bridge protective agent according to claim 1, characterized in that said siloxane monomer comprises methacryloxypropyltrimethoxysilane, aminopropyltriethoxysilane and epoxy One or more mixtures of propoxymethyltrimethoxysilanes are used in an amount of 10-40% of the total weight of nano oxides in the alcohol solution of inorganic nano materials. 6. The preparation method of the steel structure bridge protective agent described in any one of claims 1-5, is characterized in that comprising the following steps: 1) Preparation of organic/inorganic composite fluorosilicone styrene-acrylic polymer emulsion The use of fluoride monomers, siloxane monomers, methyl methacrylate, styrene, butyl acrylate, methacrylic acid, hydroxyethyl methacrylate, emulsifiers, initiators, surface-modified inorganic nanomaterials Hydrosol, prepared by semi-continuous emulsion polymerization; 2) dissolving benzotriazole in absolute ethanol to form an alcoholic solution; 3) Stir and mix the solutions obtained in steps 1) and 2), lithium silicate, sodium molybdate, sodium gluconate, nano-titanium dioxide, sodium tetraborate and ethanolamine with distilled water to obtain a steel bridge protective agent. 7. An application method of the steel structure bridge protective agent according to any one of claims 1-5, characterized in that, it is applied to the surface of the steel structure bridge by mechanical spraying or manual coating.

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