Roller pre-film agent, roller and method for manufacturing the same

Abstract

The application provides a roller pre-film agent, a roller and a preparation method thereof. The roller pre-film agent comprises the following components in percentage by mass: water glass 30-45%, silica sol 8-15%, silane coupling agent 0.5-2%, nano silicon dioxide 10-20%, micron alpha-Al2O 3 3-8%, nano titanium dioxide 2-6%, nano magnesium oxide 2-5%, glass flake 5-10%, mica powder 3-7%, flaky zinc-based active filler 2-5%, organic dispersing and water-retaining agent 3-6%, defoaming agent 0.1-0.5%, and the rest is deionized water. The roller pre-film agent can form a pre-film protective layer on the surface of the roller base body, and can effectively improve the problems of traditional roller bite slip and surface corrosion.

Description

Technical Field

[0001] This application relates to the field of metal surface treatment and protection technology, and in particular to a roll pre-filming agent, a roll, and a method for preparing the same. Background Technology

[0002] In the steel rolling production process of bar mills and wire rod mills in the steel smelting industry, rolls are one of the core tools and dies. When rolling red-hot steel (high-temperature steel billets), the work rolls of each stand in the roughing, intermediate, and finishing mills rely on the friction between the rolls and the red-hot steel to achieve reliable engagement and stable rolling. The friction state between the rolls and the high-temperature red-hot steel directly determines the stability of the rolling process and the quality of the final product.

[0003] However, in actual production, the lack of friction on the roll surface often leads to difficulties in the hot steel biting in and slippage, resulting in steel pile-up, scrap steel, and production interruption. This has become a common problem in the industry that restricts rolling efficiency and product quality.

[0004] Currently, the main technical means in the industry to solve the above problems include physical grinding and "sandblasting" processes. Physical grinding involves manually grinding the surface of the rolling mill groove with a hand-held grinding wheel before a new roll is put into service or after a groove change, creating a rough surface to increase friction. This method is labor-intensive and inefficient; the metal dust generated during grinding poses serious occupational health risks; and manual grinding with rotating rolls is highly prone to mechanical injury accidents, posing a serious risk of personal injury.

[0005] The "sand-sprinkling" process involves sprinkling abrasive materials such as sand into the roll gap during the initial rolling process to temporarily increase the coefficient of friction. This method is crude, not only resulting in inconsistent effectiveness but also exacerbating uneven wear on the roll surface and shortening the roll's service life.

[0006] Besides slippage, the surface of the rolls comes into contact with the cooling water and air during the rolling process or when the mill is stopped for rolling, resulting in severe corrosion. This necessitates manual grinding during re-rolling or slot changes, leading to discontinuous production and low efficiency. Furthermore, the unevenness of the roll surface due to grinding, or defects such as rust and pitting, results in poor surface smoothness and pitting on the rolled steel, making it difficult to meet the requirements for high-quality steel rolling, leading to low yield and high scrap rates.

[0007] Therefore, there is an urgent need to provide a solution that can address the two core pain points of "slippage during roll insertion" and "surface corrosion". Summary of the Invention

[0008] Based on this, this application provides a roll pre-filming agent, a roll, and a method for preparing the same, aiming to solve the technical problems of bite-in slippage and surface corrosion in traditional rolls.

[0009] According to a first aspect of this application, a roll pre-filming agent is provided, comprising the following components by mass percentage: 30%~45% water glass, 8%~15% silica sol, 0.5%~2% silane coupling agent, 10%~20% nano silica, 3%~8% micron α-Al2O3, 2%~6% nano titanium dioxide, 2%~5% nano magnesium oxide, 5%~10% glass flakes, 3%~7% mica powder, 2%~5% flaky zinc-based active filler, 3%~6% organic dispersant and water-retaining agent, 0.1%~0.5% defoamer, with the balance being deionized water.

[0010] In some embodiments, the components, by mass percentage, include: 35%–40% water glass, 10%–12% silica sol, 1%–1.5% silane coupling agent, 12%–16% nano silica, 4%–6% micron α-Al₂O₃, 3%–5% nano titanium dioxide, 3%–4% nano magnesium oxide, 6%–8% glass flakes, 4%–6% mica powder, 3%–4% flaky zinc-based active filler, 4%–5% organic dispersant and water-retaining agent, 0.2%–0.3% defoamer, with the balance being deionized water.

[0011] In some embodiments, the mass ratio of the water glass to the silica sol is (3~5):1.

[0012] In some embodiments, the sum of the mass percentages of the nano-silica, the micron-sized α-Al2O3, the nano-titanium dioxide, and the nano-magnesium oxide is 20% to 35%, based on the total mass of the roll pre-filming agent.

[0013] In some embodiments, the sum of the mass percentages of the glass flakes and the mica powder is 8% to 17%, based on the total mass of the roll pre-filming agent.

[0014] In some embodiments, the water glass includes one or more of sodium water glass and potassium water glass.

[0015] In some embodiments, the modulus of the water glass is 2.8 to 3.5.

[0016] In some embodiments, the silica sol contains 30% to 40% silica by mass.

[0017] In some embodiments, the particle size of silica in the silica sol is 10 nm to 50 nm.

[0018] In some embodiments, the silane coupling agent is an oligomer-type silane coupling agent, which includes epoxy siloxane oligomers.

[0019] In some embodiments, the average particle size of the nano-silica is 30 nm to 80 nm.

[0020] In some embodiments, the average particle size of the micron-α-Al2O3 is 0.5 μm to 5 μm.

[0021] In some embodiments, the average particle size of the nano-titanium dioxide is 20 nm to 50 nm.

[0022] In some embodiments, the average particle size of the nano-magnesium oxide is 30 nm to 60 nm.

[0023] In some embodiments, the glass flakes have a diameter of 80-120 mesh and a thickness of 2-10 μm.

[0024] In some embodiments, the mica powder has a particle size of 400 mesh to 800 mesh and an aspect ratio greater than 50.

[0025] In some embodiments, the sheet-like zinc-based active filler is a zinc sheet or a zinc-aluminum alloy sheet, and the D50 particle size of the sheet-like zinc-based active filler is 2μm~10μm.

[0026] In some embodiments, the organic dispersant and water-retaining agent is a mixture of ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose.

[0027] According to a second aspect of this application, a method for preparing a pre-filming agent for a roll according to the first aspect of this application is provided, comprising the following steps:

[0028] Nano-silica, nano-titanium dioxide and nano-magnesium oxide are mixed and ball-milled to obtain oxide powder;

[0029] Micron-sized α-Al2O3, glass flakes, mica powder, flaky zinc-based active filler, and the oxide powder are mixed to obtain a mixed filler;

[0030] Water glass, silica sol and silane coupling agent are mixed to obtain a composite inorganic binder base liquid;

[0031] The organic dispersant and water-retaining agent were mixed with deionized water to obtain an organic dispersant and water-retaining agent solution;

[0032] The organic dispersion is mixed with the water-retaining agent solution, the mixed filler, the composite inorganic binder base liquid and the defoamer to obtain the roll pre-filming agent.

[0033] According to a third aspect of this application, a roll is provided, comprising a roll substrate and a pre-film protective layer, the pre-film protective layer being disposed on at least a portion of the surface of the roll substrate, the pre-film protective layer being obtained by drying and curing a roll pre-filming agent of the first aspect of this application.

[0034] In some embodiments, the thickness of the pre-film protective layer is 300 μm to 500 μm.

[0035] In some embodiments, the surface roughness Ra of the pre-film protective layer is greater than or equal to 12.5 μm.

[0036] In some embodiments, the interfacial adhesion strength between the pre-film protective layer and the roll substrate is greater than or equal to 5 MPa.

[0037] In some embodiments, the cohesive strength of the pre-film protective layer is less than or equal to 25 MPa.

[0038] In some embodiments, the material of the roll matrix includes one or more of hot work die steel, alloy cast iron, high-speed steel, and cemented carbide.

[0039] According to a fourth aspect of this application, a method for preparing a roll according to a third aspect of this application is provided, comprising the following steps: coating a roll pre-filming agent according to a first aspect of this application onto the surface of a roll substrate to form a wet film; and drying and curing the wet film to form a pre-filming protective layer.

[0040] Compared with traditional technologies, this application has at least the following beneficial effects:

[0041] The roll pre-filming agent of this application comprises an inorganic composite binder system consisting of water glass, silica sol, and silane coupling agent, supplemented with functional fillers composed of nano-silica, micron-sized α-Al2O3, nano-titanium dioxide, and nano-magnesium oxide; a sheet-like corrosion-resistant barrier filler composed of glass flakes and mica powder; a zinc-based active metal anti-corrosion filler; and an organic dispersant and water-retaining agent, forming a room-temperature curing oxide ceramic roll pre-filming agent slurry system. Through the synergistic effect of each component at specific dosages, the pre-filming protective layer formed on the roll substrate after drying and curing possesses controllable self-pulverizing properties. Under the deformation pressure of red steel, it can controllably and automatically break down and pulverize, filling the space between the roll and the red steel with uniform particles, providing excellent bite friction and improving the problem of roll slippage. Furthermore, the pre-filming protective layer has good water resistance, corrosion resistance, and impermeability, effectively improving the problem of rust on the roll surface. Detailed Implementation

[0042] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0043] Unless otherwise defined, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.

[0044] In the actual production process of steel smelting, the lack of friction on the surface of the rolls leads to difficulties in the entry of red steel and slippage, resulting in steel pile-up, scrap steel and production interruption. This has become a common problem in the industry that restricts the efficiency and product quality of steel rolling.

[0045] The main solutions to these problems in the industry include physical grinding and "sandblasting" processes. However, physical grinding is labor-intensive and inefficient, and the metal dust generated poses serious occupational health risks. Manual grinding with rotating rolls is highly prone to mechanical injury accidents, posing a serious risk of personal injury. The "sandblasting" process is crude, not only resulting in inconsistent effects but also exacerbating uneven wear on the roll surface and shortening the roll's service life.

[0046] Furthermore, during the rolling process or when the mill is stopped for rolling, the surface of the rolls comes into contact with the cooling water and air of the rolling line, resulting in severe corrosion. When the rolls are reused or the mill is changed, the mill needs to be stopped again for manual grinding, leading to discontinuous production and low efficiency. The uneven surface of the rolls due to grinding, or defects such as rust and pitting, results in poor surface smoothness and pitting on the rolled steel, making it difficult to meet the rolling requirements of high-quality steel, resulting in low yield and high scrap rate.

[0047] In response, one embodiment of this application provides a roll pre-filming agent, which comprises the following components by mass percentage: 30%~45% water glass, 8%~15% silica sol, 0.5%~2% silane coupling agent, 10%~20% nano silica, 3%~8% micron α-Al2O3, 2%~6% nano titanium dioxide, 2%~5% nano magnesium oxide, 5%~10% glass flakes, 3%~7% mica powder, 2%~5% flaky zinc-based active filler, 3%~6% organic dispersant and water-retaining agent, 0.1%~0.5% defoamer, and the balance being deionized water.

[0048] The roll pre-filming agent described in this application is a room-temperature curing oxide ceramic pre-filming coating slurry system composed of inorganic silicon-based materials as the binder matrix, supplemented with functional fillers, flake-shaped corrosion-resistant barrier fillers, and active metal anti-corrosion fillers. This roll pre-filming agent can be prepared by a slurry method. After being coated onto the surface of the roll substrate, it is dried and cured at room temperature or medium-low temperature (not exceeding 80°C) to form a pre-filming protective layer with specific roughness, adhesive strength, and controllable self-powdering characteristics.

[0049] In the aforementioned roll pre-coating agent, specific amounts of water glass, silica sol, and silane coupling agent form an inorganic composite binder system. Water glass, as the primary inorganic binder, can dehydrate and condense at room temperature to form a Si-O-Si gel network, which can form Si-O-Fe chemical bonds with the roll substrate surface. Silica sol, as an auxiliary binder, contains nano-sized SiO2 particles that can fill the gel micropores, improving the coating's density, water resistance, and room-temperature curing strength. The silane coupling agent can improve the interfacial bonding force between the glass flakes, mica powder, and the silicate matrix in the inorganic composite binder system, thus improving compatibility.

[0050] If water glass is used alone as an inorganic binder, the coating after room temperature curing has the following two inherent defects: firstly, residual alkali metal ions (Na₂O₃)... + K + Firstly, the coating's water resistance is reduced due to its hygroscopic nature; secondly, significant volume shrinkage during drying and curing can easily lead to microcracks. The nano-SiO2 particles in the silica sol physically fill the micropores and microcracks formed by the condensation reaction of water glass, increasing the coating's toughness and density. Simultaneously, the dispersed SiO2 particles in the silica sol possess extremely high surface activity and penetrating power, further enhancing the coating's adhesion to the metal substrate.

[0051] The dosage of water glass, silica sol, and silane coupling agent in the aforementioned inorganic composite binder system is crucial for achieving the "controllable self-powdering" mechanical properties of the coating. Through the specific formulation of this application, it is ensured that the cured coating can resist high-pressure erosion from online cooling water and is resistant to corrosion in humid environments, while maintaining moderate stiffness and limiting its cohesive strength to within 25 MPa.

[0052] Controllable self-powdering refers to the coating's ability to automatically and controllably break down into powder under the deformation pressure of the red steel during the rolling process, filling the space between the roll and the red steel with uniform particles to provide excellent biting friction, rather than forming large, thin pieces of coating fragments.

[0053] A functional filler system is composed of specific amounts of nano-silica, micron-sized α-Al₂O₃, nano-titanium dioxide, and nano-magnesium oxide. Nano-silica, acting as an aggregate reinforcing phase, is itself a component of the silicate system and exhibits excellent chemical compatibility with the binder, significantly improving the coating's density and surface hardness. Micron-sized α-Al₂O₃ possesses excellent thermal stability and mechanical strength, serving as a strength limiting point and fracture source within the coating. Its micron-sized particle size design ensures that when the coating fractures, it forms uniform, isolated powder with these particles as its core, rather than large flakes. Nano-titanium dioxide enhances interfacial bonding and improves density in the coating; its surface Ti-OH groups can condense with silicate gel, strengthening the particle-matrix interface. Nano-magnesium oxide has a thermal expansion coefficient close to that of the steel roll matrix, effectively adjusting the overall thermal expansion coefficient of the coating and reducing interfacial stress caused by thermal expansion mismatch during steel rolling heating.

[0054] Glass flakes are extremely thin, glassy sheet-like fillers manufactured using a special process. During slurry spraying and drying, under the influence of shear force from the roller substrate surface and surface tension of the coating, the glass flakes tend to align parallel to the roller substrate surface within the coating. This "tile-like" layered structure creates a tortuous, labyrinthine penetration path within the coating, allowing water vapor, oxygen, and corrosive ions (such as Cl-) to pass through. - The penetration distance is greatly extended (up to tens of times the straight-line distance), thereby significantly improving the coating's water resistance, corrosion resistance and impermeability.

[0055] Mica powder is a natural layered silicate mineral (its main components are KAl2(AlSi3O)). 10 Mica ((OH)₂) exhibits excellent chemical stability in alkaline silicate environments. In the coating, the mica flakes are also horizontally oriented, working synergistically with the glass flakes to form multiple barrier layers. Furthermore, mica possesses good elasticity and toughness, which can alleviate the internal stress generated by coating curing shrinkage to a certain extent, inhibiting crack initiation.

[0056] Furthermore, the layered interface formed by glass flakes and mica powder in the coating is a relatively weakened region. When the coating is subjected to high pressure during steel processing, cracks preferentially propagate along these layered interfaces, allowing the coating to controllably fragment into relatively uniform sheet-like or granular fragments, rather than peeling off in large pieces. This characteristic is the key structural basis for achieving the "controllable self-powdering" of the coating.

[0057] The electrode potential of the sheet-like zinc-based active filler is lower than that of the steel roll substrate, enabling cathodic protection of the rolls and online equipment through the sacrificial anode principle. In the electrochemical sequence, the standard electrode potential of zinc is -0.76V (vs SHE), significantly lower than that of the steel roll substrate. When the rolling line is in a humid environment (cooling water, moisture), the zinc-based active filler particles in the coating come into contact with the steel substrate surface and are simultaneously exposed to the electrolyte film, forming numerous micro-corrosion galvanic couples.

[0058] In this micro-region electrode pair, the zinc-based active filler, acting as the anode, preferentially undergoes oxidative dissolution:

[0059] Anodic reaction (zinc dissolution): Zn → Zn 2+ +2e - ;

[0060] Cathodic reaction (oxygen reduction on steel surface): O2 + 2H2O + 4e - →4OH - ;

[0061] When corrosive media penetrate, the zinc-based active filler, with its lower potential, preferentially undergoes oxidation and dissolves as the anode, thus protecting the roll substrate and related equipment from corrosion, achieving cathodic protection using a sacrificial anode. Because the zinc-based active filler is uniformly distributed in the coating as discrete particles, rather than a traditional external sacrificial anode block, its effective dissolution area is controlled by the slow release of the coating's porosity and water content. This results in a moderate and uniformly distributed protective current density, preventing overprotection phenomena (such as hydrogen embrittlement and coating cathodic stripping) caused by excessive protective current, as seen in impressed current cathodic protection.

[0062] Specific dosages of organic dispersants and water-retaining agents achieve a balance between dispersion and water retention, ensuring uniform dispersion of nano and micron-sized inorganic fillers in alkaline water glass slurry and improving the spray rheological properties of the roll pre-coating agent slurry. Specific dosages of defoamers eliminate air bubbles introduced during mixing and spraying of the roll pre-coating agent slurry, reducing pinhole defects in the coating. Specific dosages of deionized water help adjust the viscosity of the roll pre-coating agent slurry to a suitable range for spraying.

[0063] In some embodiments, the roll pre-filming agent comprises the following components by mass percentage: 35%~40% water glass, 10%~12% silica sol, 1%~1.5% silane coupling agent, 12%~16% nano silica, 4%~6% micron α-Al2O3, 3%~5% nano titanium dioxide, 3%~4% nano magnesium oxide, 6%~8% glass flakes, 4%~6% mica powder, 3%~4% flaky zinc-based active filler, 4%~5% organic dispersant and water-retaining agent, 0.2%~0.3% defoamer, and the balance being deionized water.

[0064] Controlling the dosage of each component of the roll pre-coating agent within the above-mentioned range is more conducive to improving the controllable self-powdering performance and cathodic protection of the coating, and more conducive to improving the surface controllable friction enhancement, long-term rust prevention and cathodic protection functions of the roll using this roll pre-coating agent.

[0065] In some embodiments, the mass ratio of water glass to silica sol is (3~5):1. Further controlling the mass ratio of water glass to silica sol in the roll pre-filming agent within the above range for composite use can produce a significant synergistic effect: water glass provides excellent chemical affinity to the steel roll substrate (through the formation of Si-OM covalent bonds between surface Si-OH and substrate metal oxides), and the nano-SiO2 particles in the silica sol penetrate into the micropores of the water glass gel network, undergoing a condensation reaction with the silanol groups of water glass during room temperature drying to form a denser and more uniform Si-O-Si three-dimensional cross-linked structure. Maintaining the mass ratio of water glass to silica sol within the above range allows the composite system to achieve high curing strength at room temperature without the need for high-temperature sintering, while significantly improving the coating's water resistance and resistance to damp heat.

[0066] It is understandable that the mass ratio of water glass to silica sol can be 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1, or any ratio within the range formed by any two of the above ratios.

[0067] In some embodiments, the sum of the mass percentages of nano-silica, micron-sized α-Al₂O₃, nano-titanium dioxide, and nano-magnesium oxide is 20% to 35%, based on the total mass of the roll pre-filming agent. Controlling the sum of the mass percentages of nano-silica, micron-sized α-Al₂O₃, nano-titanium dioxide, and nano-magnesium oxide within this range is more conducive to ensuring coating strength, reducing coating brittleness, reducing the risk of coating shrinkage and cracking, and improving the prevention of unexpected powder shedding during storage. Simultaneously, it allows the roll pre-filming agent to have suitable viscosity and good spraying performance.

[0068] It is understandable that the sum of the mass percentages of nano-silica, micron-sized α-Al2O3, nano-titanium dioxide, and nano-magnesium oxide in the roll pre-filming agent can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or any value within the range formed by any two of the above values.

[0069] In some embodiments, the sum of the mass percentages of glass flakes and mica powder is 8% to 17%, based on the total mass of the roll pre-coating agent. This is beneficial for better controlling the barrier effects of water vapor, oxygen, and corrosive ions in the coating, as well as the self-powdering effect of the coating; it is also beneficial for improving the flowability and spraying performance of the roll pre-coating agent.

[0070] It is understandable that the sum of the mass percentages of glass flakes and mica powder in the roll pre-filming agent can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or any value within the range formed by any two of the above values.

[0071] In some embodiments, the water glass includes one or more of sodium silicate and potassium silicate. Sodium silicate is an aqueous solution of sodium silicate, and potassium silicate is an aqueous solution of potassium silicate. In some specific examples, potassium silicate is used. Compared to sodium silicate, potassium silicate has better water resistance.

[0072] In some embodiments, the modulus of the water glass is 2.8 to 3.5. Setting the modulus of the water glass within this range is beneficial for maintaining a suitable molar ratio of SiO2 to alkali metal oxides, allowing the inorganic binder to exist primarily as a highly polymerized silicon-oxygen tetrahedral network structure, thus exhibiting both better adhesion and aging resistance. Here, the modulus of the water glass refers to the molar ratio of silicon dioxide to alkali metal oxides in the water glass.

[0073] It is understandable that the modulus of water glass can be 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4, 3.5, or any value within the range formed by any two of the above values.

[0074] In some embodiments, the mass fraction of silica in the silica sol is 30% to 40%. It is understood that the mass fraction of silica in the silica sol can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or any value within the range formed by any two of the above values.

[0075] In some embodiments, the particle size of silica in the silica sol is 10nm to 50nm. Thus, the silica in the silica sol possesses extremely high surface activity and penetrating power, which is beneficial for improving the adhesion of the coating to the metal substrate. It is understood that the particle size of silica in the silica sol can be 10nm, 12nm, 15nm, 18nm, 20nm, 22nm, 25nm, 28nm, 30nm, 32nm, 35nm, 38nm, 40nm, 42nm, 45nm, 48nm, 50nm, or any value within the range formed by any two of the above values. Here, particle size refers to the average particle size.

[0076] In some embodiments, the silane coupling agent is an oligomeric silane coupling agent, including epoxy siloxane oligomers. Non-limitingly, the silane coupling agent may be Evonik Dynasylan 1151 type oligomeric silane coupling agent. This siloxane oligomer is a "hydrolysis-free" interfacial tackifier with a pre-constructed Si-O-Si framework structure within the molecule. Unlike traditional small-molecule silane coupling agents (such as KH560) that require on-site hydrolysis activation, this type of oligomer is itself a siloxane condensation product. The active silanol groups retained at the molecular ends can directly undergo a dehydration condensation reaction with M-OH (M can be Fe) on the surface of the metal roll substrate, forming a strong Si-OM covalent bond transition layer between the coating and the metal substrate. Simultaneously, the multiple siloxane units on the oligomer chain enable it to chemically bond and physically entangle with the silica sol particles in the system, forming a "multi-toothed anchoring" effect, providing stronger interfacial bonding and durability compared to single-point connected monomeric silanes. Since the epoxy-based siloxane oligomers no longer undergo the uncontrolled hydrolysis and self-polymerization of traditional silanes in strongly alkaline water glass-silica sol-based solutions, but exist in a stable oligomer form, the storage stability and application period of the pre-filming agent slurry are significantly improved, and no small-molecule alcohols are released, resulting in a substantial reduction in VOC emissions. Furthermore, its side-chain epoxy groups can slowly open in an alkaline environment with the assistance of nucleophilic groups such as amino groups, further participating in the interfacial crosslinking reaction and strengthening the density of the organic-inorganic hybrid transition layer, thus contributing to excellent coating adhesion and water and corrosion resistance under room temperature curing conditions.

[0077] In some embodiments, the average particle size of the nano-silica is 30nm to 80nm. It is understood that the average particle size of the nano-silica can be 30nm, 35nm, 38nm, 40nm, 45nm, 48nm, 50nm, 55nm, 58nm, 60nm, 65nm, 68nm, 70nm, 75nm, 78nm, 80nm, or any value within the range formed by any two of the above values.

[0078] In some embodiments, the average particle size of micron-α-Al₂O₃ is 0.5 μm to 5 μm. Controlling the average particle size of micron-α-Al₂O₃ within this range is beneficial for forming uniform, isolated powder with these particles as the core when the coating breaks down, rather than large flakes.

[0079] It is understandable that the average particle size of micron-sized α-Al2O3 can be 0.5μm, 0.8μm, 1μm, 1.5μm, 1.8μm, 2μm, 2.5μm, 2.8μm, 3μm, 3.5μm, 3.8μm, 4μm, 4.5μm, 4.8μm, 5μm, or any value within the range formed by any two of the above values.

[0080] In some embodiments, the average particle size of nano-titanium dioxide is 20 nm to 50 nm. It is understood that the average particle size of nano-titanium dioxide can be 20 nm, 22 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 45 nm, 48 nm, 50 nm, or any value within the range formed by any two of the above values.

[0081] In some embodiments, the average particle size of the nano-magnesium oxide is 30 nm to 60 nm. It is understood that the average particle size of the nano-magnesium oxide can be 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 45 nm, 48 nm, 50 nm, 52 nm, 55 nm, 58 nm, 60 nm, or any value within the range formed by any two of the above values.

[0082] In some embodiments, the glass flakes have a diameter of 80-120 mesh and a thickness of 2μm-10μm. It is understood that the glass flake diameter can be 80 mesh, 85 mesh, 88 mesh, 90 mesh, 95 mesh, 98 mesh, 100 mesh, 105 mesh, 108 mesh, 110 mesh, 115 mesh, 118 mesh, 120 mesh, or any value within the range formed by any two of the above values. The glass flake thickness can be 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any value within the range formed by any two of the above values.

[0083] In some embodiments, the mica powder has a particle size of 400-800 mesh and an aspect ratio greater than 50. It is understood that the particle size of the mica powder can be 400 mesh, 420 mesh, 450 mesh, 480 mesh, 500 mesh, 520 mesh, 550 mesh, 580 mesh, 600 mesh, 620 mesh, 650 mesh, 680 mesh, 700 mesh, 720 mesh, 750 mesh, 780 mesh, 800 mesh, or any value within the range formed by any two of the above values.

[0084] In some embodiments, the sheet-like zinc-based active filler is a zinc sheet or a zinc-aluminum alloy sheet, and the D50 particle size of the sheet-like zinc-based active filler is 2μm to 10μm. It is understood that the D50 particle size of the sheet-like zinc-based active filler can be 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any value within the range formed by any two of the above values.

[0085] Furthermore, since zinc and aluminum may react chemically to produce hydrogen in a strongly alkaline water glass environment, affecting the stability of the slurry, this application preferably uses flake zinc powder / zinc-aluminum alloy powder with a surface passivation treatment of silane coupling agent or phosphate to ensure that the electrochemical activity of the active filler and the stability of the slurry are both considered during construction.

[0086] In some embodiments, the organic dispersant and water-retaining agent is a mixture of ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose. The mass ratio of ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose in the organic dispersant and water-retaining agent can be (10~15):(3~8):(1~3). The organic dispersant and water-retaining system formed by the ternary compound of ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose (HPMC) achieves a unified dispersion and water retention effect through functional complementarity and synergistic effect.

[0087] Among them, ammonium polyacrylate, as a polyelectrolyte, has a large number of dissociated carboxylate groups (-COO) on its molecular chain. - In an alkaline silica sol-water glass system, these components adsorb onto the surfaces of nano- and micro-sized oxide fillers, causing the particle surfaces to carry a negative charge and generating electrostatic repulsion. Simultaneously, the extended polyanionic chains provide a steric hindrance layer, and both work synergistically to prevent filler agglomeration and sedimentation. Polyethylene glycol, as a nonionic polymer, adsorbs onto the filler surface via hydrogen bonding, forming a flexible protective shell that interpenetrates and overlaps with the steric hindrance layer of ammonium polyacrylate, further enhancing the steric shielding effect and improving the rheological properties of the slurry. Hydroxypropyl methylcellulose constructs a three-dimensional network structure in the system through the hydration entanglement of its molecular chains, significantly increasing low-shear viscosity and yield stress to delay filler sedimentation and prevent spray sagging. Simultaneously, its strongly hydrophilic groups bind free water molecules through hydrogen bonds, creating a physical water-locking effect, enabling uniform and slow-release drying of the coating from the surface inwards during room-temperature curing, avoiding premature skinning and internal stress cracking. The three components respectively perform the functions of electrostatic dispersion, steric hindrance, and thickening and water retention, working together to ensure that the multi-component fillers such as nano-oxides, glass flakes, and mica powder in the slurry remain in a long-term uniform suspension in a strongly alkaline and high-ionic-strength environment, and maintain a stable physical state throughout the entire process of spraying and drying curing, resulting in a high-quality coating with uniform microstructure and no segregation defects.

[0088] The aforementioned organic dispersion and water-retaining system is not used as a film-forming substance, but mainly as a temporary process aid. During the slurry preparation and storage stages, the organic dispersion and water-retaining system significantly improves the suspension stability of high-solids-content inorganic slurries, preventing solid filler sedimentation. During the coating application stage, it imparts suitable rheological properties and water retention to the slurry, facilitating spraying or brushing application and forming a smooth and uniform wet film. During the room-temperature drying stage, it slows down the rate of moisture evaporation, preventing the coating from shrinking and cracking due to excessive water loss, ensuring a smooth and continuous coating. When in contact with high-temperature red-hot steel, the aforementioned organic dispersion and water-retaining system can undergo instantaneous pyrolysis and escape, forming directional micropores within the coating, assisting in inducing stress concentration and cohesive fragmentation of the coating.

[0089] One embodiment of this application provides a method for preparing the roll pre-filming agent described above, the method comprising the following steps S100 to S400:

[0090] Step S100: Mix and ball-mill nano-silica, nano-titanium dioxide and nano-magnesium oxide to obtain oxide powder; mix micron α-Al2O3, glass flakes, mica powder, flaky zinc-based active filler and oxide powder to obtain mixed filler.

[0091] In some embodiments, nano-silica, nano-titanium dioxide, and nano-magnesium oxide are weighed according to the formula ratio and added to a planetary ball mill. Triethanolamine is used as a grinding aid, and the milling speed is 250 r / min for 16 h to 24 h to ensure uniform mixing of the powder and achieve the target particle size. Al2O3 balls with diameters of 5 mm, 2 mm, and 1 mm are used in a mass ratio of 6:3:1. After ball milling, the powder is dried at 80℃ for 24 h and then passed through a 200-mesh sieve for later use.

[0092] Then, the α-Al2O3, flaky zinc-based active filler, glass flakes, mica powder and other powder fillers, along with the above nano-oxide powders, are added to a V-type mixer and stirred continuously at 300 rpm to 500 rpm for 20 min to 30 min to obtain a homogeneous mixed filler.

[0093] Step S200: Mix water glass, silica sol and silane coupling agent to obtain composite inorganic binder base liquid.

[0094] In some embodiments, water glass and silica sol are mixed in a mass ratio, and a silane coupling agent of the prescribed amount is added. The mixture is stirred at a speed of 100 r / min to 300 r / min for 10 min to 30 min to ensure that the components are fully mixed and homogeneous, thereby obtaining a composite inorganic binder base liquid.

[0095] Step S300: Mix the organic dispersant and water-retaining agent with deionized water to obtain an organic dispersant and water-retaining agent solution.

[0096] In some embodiments, ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose are mixed in a mass ratio of (10~15):(3~8):(1~3), and an appropriate amount of deionized water is added. The mixture is stirred at a speed of 100r / min~300r / min for 10min~30min to obtain an organic dispersion and water-retaining agent solution with a solid content of 10%~20%.

[0097] Step S400: Mix the organic dispersion with the water-retaining agent solution, the mixed filler, the composite inorganic binder base liquid and the defoamer to obtain the roll pre-filming agent.

[0098] In some embodiments, the pre-dispersed mixed filler is slowly added to the composite inorganic binder base liquid under slow stirring at 100 rpm to 300 rpm, while simultaneously adding the prescribed amount of defoamer and the above-mentioned organic dispersant and water-retaining agent solution. After the addition is completed, shearing and stirring are continued at 800 rpm to 1200 rpm for 30 minutes to ensure that all components are fully and uniformly dispersed. The solid content of the slurry is controlled at 55% to 70%, and the viscosity (Ford cup 4, 25°C) is controlled at 20 s to 40 s. After standing and defoaming, the roll pre-filming agent is obtained.

[0099] One embodiment of this application provides a roll, including a roll substrate and a pre-film protective layer. The pre-film protective layer is disposed on at least a portion of the surface of the roll substrate and is obtained by drying and curing the roll pre-filming agent described above in this application.

[0100] The aforementioned roll has a pre-film protective layer on at least a portion of the roll substrate surface. This pre-film protective layer is obtained by drying and curing the roll pre-filming agent described in this application. This pre-film protective layer exhibits good controllable self-pulverization properties and cathodic protection. The adhesion strength between the pre-film protective layer and the roll substrate is sufficient to resist the high-pressure erosion of online cooling water; the suitable cohesive strength of the pre-film protective layer allows it to be precisely broken into powder under the enormous rolling shear force at the moment of hot steel engagement. The uniform granular powder formed after the pre-film protective layer is broken can effectively fill the space between the roll and the hot steel, playing a role in increasing friction, preventing slippage, and assisting in engagement.

[0101] During non-rolling operations, the pre-film protective layer, when intact, acts as an isolation and protection mechanism, preventing water and air from corroding the roll substrate. The low-electrode-potential metal powder (zinc-based active filler) added to the pre-film protective layer can form a sacrificial anode protection circuit with the roll and mill, providing electrochemical cathodic protection for the roll and related equipment.

[0102] In summary, this pre-film protective layer requires no complex thermal spraying equipment, can be applied at room temperature and naturally cures to form a pre-film protective layer on the roll surface, significantly reducing process costs and safety risks, and facilitating on-site promotion. This pre-film protective layer provides dense protection during roll storage and pre-rolling, isolating moisture and air, preventing roll corrosion and pitting, and eliminating the need for a secondary grinding process before re-rolling. During steel passage, the pre-film protective layer can be controllably and automatically pulverized under the deformation pressure of the red-hot steel, filling the space between the roll and the red-hot steel with uniform particles, providing excellent bite friction, fundamentally helping the red-hot steel to bite smoothly and preventing slippage. After the pre-film protective layer pulverizes and detaches, it does not damage the roll substrate, and the roll surface is free of rust and pitting, significantly improving the surface quality and yield of rolled steel. The pre-film protective layer contains zinc-based active fillers with an electrode potential lower than that of the steel substrate, which can form a sacrificial anode type corrosion galvanic protection with the roll and online equipment, effectively mitigating the electrochemical corrosion of the roll and rolling equipment.

[0103] In some embodiments, the thickness of the pre-film protective layer is 300 μm to 500 μm. This is beneficial for the pre-film protective layer to have better friction-enhancing and anti-slip properties, assist in biting, and protect the roll substrate. It is understood that the thickness of the pre-film protective layer can be 300 μm, 320 μm, 350 μm, 380 μm, 400 μm, 420 μm, 450 μm, 480 μm, 500 μm, or any value within the range formed by any two of the above values.

[0104] In some embodiments, the surface roughness Ra of the pre-film protective layer is greater than or equal to 12.5 μm. This is beneficial for achieving good friction-enhancing, anti-slip, and bite-aiding effects.

[0105] In some embodiments, the interfacial adhesion strength between the pre-film protective layer and the roll substrate is greater than or equal to 5 MPa. Thus, the pre-film protective layer can effectively resist the high-pressure erosion of online cooling water.

[0106] In some embodiments, the cohesive strength of the pre-film protective layer is less than or equal to 25 MPa. This facilitates the precise crushing of the pre-film protective layer into powder under the enormous rolling shear force at the moment of steel biting in, thus providing good friction enhancement, anti-slip properties, and assistance in biting in.

[0107] In some embodiments, the material of the roll substrate includes one or more of hot work die steel, alloy cast iron, high-speed steel, and cemented carbide. The roll pre-filming agent and pre-filming protective layer of this application are applicable to roll substrates of the aforementioned various materials. For roll substrates of different materials, only the sandblasting roughening process parameters need to be adjusted; the formulation of the roll pre-filming agent does not need to be changed.

[0108] One embodiment of this application provides a method for preparing the roll described above, comprising the following steps: coating the roll pre-filming agent described above onto the surface of the roll substrate to form a wet film; and drying and curing the wet film to form a pre-filming protective layer.

[0109] In some embodiments, the roll pre-filming agent slurry of this application is uniformly coated onto the working surface of the roll groove of the roll substrate by spraying or brushing. Preferably, a pneumatic spraying method is used to spray the roll pre-filming agent slurry onto the working surface of the roll groove of the roll substrate, with an air pressure of 0.3MPa~0.6MPa, a spraying angle of 30°~60°, and a spraying distance of 200mm~300mm. A multi-coat thin-coat method is used, with the wet film thickness of each coat controlled at 100μm~150μm, and each coat surface drying at 10min~15min intervals, resulting in a total dry film thickness controlled at 300μm~500μm. The multiple thin-coat spraying method is beneficial for interlayer bonding and air bubble removal.

[0110] In some embodiments, a pretreatment step of the roll substrate is included before spraying or brushing the roll pre-filming agent slurry onto the roll substrate. Specifically, for the machined and inspected roll substrate, an organic solvent (such as anhydrous ethanol, acetone, etc.) or industrial cleaning agent is used to remove oil stains, cutting fluid residue and debris from the surface of the roll groove to ensure that the surface of the roll substrate is clean.

[0111] In some embodiments, the coated roll substrate is placed in a well-ventilated indoor environment for natural drying and curing. Drying conditions are: ambient temperature 20°C~30°C, relative humidity <85%. Drying time is 24h~72h, until the coating is completely dry. Alternatively, it can be dried in an oven at 60°C~80°C for 12h~24h to accelerate curing, but temperatures must not exceed 100°C to prevent excessive dehydration and cracking of the coating. During this process, the inorganic composite binder system undergoes moisture evaporation and condensation reactions, and the coating gradually hardens to form a dense pre-film protective layer firmly bonded to the roll substrate.

[0112] Once the pre-film protective layer reaches a fully dry state (with an adhesion strength ≥5MPa to the roll substrate), the roll can be directly put into rolling production without any traditional auxiliary operations such as "sanding". During the rolling process, the pre-film protective layer can be easily pulverized and detached under the deformation pressure at the moment the red steel bites in, filling the gap between the rolls to assist in biting in and prevent slippage.

[0113] The pre-film protective layer prepared by the above process and cured at room temperature has the following structural characteristics and properties: (1) The macroscopic structure of the pre-film protective layer is uniformly matte and free from macroscopic defects such as bubbles and pinholes. (2) The microstructure of the pre-film protective layer can be divided into three functional layers from the surface to the bottom: the surface layer is a dense silicate gel layer reinforced with nano-oxides; the middle layer is a labyrinth barrier layer with alternating layers of glass flakes and mica powder; and the bottom layer is an interface transition bonding layer rich in Si-OM (M=Fe, Zn, etc.) chemical bonds. (3) The interfacial adhesion strength (coating adhesion) between the pre-film protective layer and the roll substrate is ≥5MPa (pull-off test), and it can resist the direct scouring of online cooling water without falling off. (4) The main body of the pre-film protective layer is an inorganic silicate system, which remains solid at temperatures above 600℃ and does not deteriorate or melt during the rolling process. (5) When the rolling contact stress exceeds its cohesive strength (≤25MPa), the pre-film protective layer undergoes controlled fragmentation, forming uniform particles with a particle size mainly distributed in the range of 50μm~150μm (this particle size is the equivalent particle size of the pulverized fragments), effectively filling the space between the roll and the red steel interface, providing mechanical interlocking, and helping the red steel to bite in smoothly. (6) The pre-film protective layer at 60℃, 90% relative humidity, and Cl - Content 0.1 mg / m 3 In an extremely accelerated corrosion environment, the protection time for the roll substrate is ≥840h; after removing the surface pre-film protective layer, the roll substrate shows no rust or electrolytic corrosion. (7) The corrosion galvanic current density between the zinc-based active filler in the pre-film protective layer and the steel substrate can be maintained at 10μA / cm. 2 ~50μA / cm 2 The mild level provides sustainable sacrificial anode cathodic protection. (8) The pre-film protective layer uses environmentally friendly and safe pre-filming agent materials, which do not contain volatile organic compounds (VOCs), have no irritating odor, are non-toxic, and meet the environmental protection requirements of industrial coating.

[0114] In summary, unlike traditional methods of increasing friction (manual grinding to thicken, sandblasting, or coatings left on the surface to provide friction), this application proposes a novel consumable pre-film protective layer that can undergo controlled fragmentation along the sheet interface under rolling pressure. Uniform particles actively fill the space between the roll and the red-hot steel interface, providing mechanical interlocking and facilitating smooth steel engagement. This pre-film protective layer disappears after steel passes through, causing no damage to the roll substrate and fundamentally solving the slippage problem.

[0115] This application innovatively combines water glass, silica sol, and silane coupling agent in a specific ratio. This system has the combined advantages of low cost (mainly water glass), high water resistance (reinforced by silica sol), and good chemical affinity with steel roll substrate. It can form a dense Si-O-Si three-dimensional gel network through dehydration condensation reaction at room temperature (20℃~30℃) or medium and low temperature (≤80℃), without the need for high-temperature sintering equipment. This makes it possible to apply the pre-film protective layer on-site at room temperature, while taking into account the workability, bonding strength, and corrosion resistance and durability.

[0116] This application innovatively introduces sheet-like laminated fillers into the roll pre-filming agent, utilizing a "tile-like" labyrinth structure formed by the parallel arrangement of glass flakes and mica powder in the pre-filming protective layer. On the one hand, this significantly extends the penetration path of water vapor and corrosive media (labyrinth barrier effect), achieving excellent water and corrosion resistance. On the other hand, it utilizes the layer interfaces as mechanically weakening regions, causing cracks in the pre-filming protective layer to preferentially propagate along the interlayer rather than fracture randomly under pressure, thereby achieving controllable self-pulverization. This achieves the unification of two seemingly contradictory functions—"protection" and "pulverization"—within the same coating.

[0117] This application disperses sheet-like zinc-based active filler in a pre-film protective layer. The sheet-like zinc-based active filler can form a large number of micro-corrosion couples with the steel roll substrate, achieving mild and controllable sacrificial anode protection, avoiding the risk of overprotection in impressed current cathodic protection, and the dissolution rate of the zinc-based active filler is controlled by the slow release of the pre-film protective layer substrate, resulting in a long-lasting and stable effect.

[0118] The roll pre-filming agent and rolls with pre-filming protective layers described in this application completely replace the traditional "manual grinding with a grinding wheel" and "sandblasting" operations before rolls are put into operation with a single "pre-filming protective layer" process. This allows rolls to be safely stored and directly put into operation after being pre-filmed in the grinding workshop or on-site, fundamentally eliminating the hazards of grinding metal dust to the respiratory system and the risk of injury to personnel from rotating equipment, significantly improving the inherent safety level of the operation and occupational health protection.

[0119] The roll pre-filming agent and pre-filming protective layer of this application simultaneously achieve three core functions that traditional technologies struggle to accomplish individually: first, they aid in gripping and prevent slippage, with the pre-filming protective layer's powdered particles filling the interface to increase friction and aid gripping; second, they provide dense corrosion protection, with the layered labyrinth barrier structure isolating moisture and protecting the roll from rust and pitting during the waiting period; and third, they provide electrochemical cathodic protection, with zinc-based active fillers inhibiting corrosion of the roll and online equipment. This solves the fundamental problem of traditional technologies that suffer from incomplete or limited functionality.

[0120] The roll construction cost of this application is extremely low, and the process has strong versatility. This application is a completely ambient temperature process, requiring no high-temperature sintering furnace, supersonic spraying equipment, special spray booths, or any other high-energy-consuming equipment; only a conventional high-pressure spray gun is needed for construction. This process can be implemented in the grinding workshop or on-site of various bar and wire rod rolling mills, without being limited by site and equipment conditions, and has the versatility for large-scale industrial promotion.

[0121] The rolls described in this application significantly improve the surface quality of rolled steel. Because the pre-film protective layer provides dense anti-corrosion protection to the roll substrate surface throughout storage and before rolling, the roll surface is smooth, rust-free, and free of pitting when it enters the rolling mill. During rolling, the pre-film protective layer powders and falls off, having no adverse effect on the steel surface, and the roll substrate itself is not damaged. Therefore, the surface smoothness and finish of the rolled steel are significantly improved, surface defects such as pitting are greatly reduced, and the yield rate is effectively improved, meeting the rolling requirements for high-quality steel.

[0122] The pre-film protective layer in the rolls of this application provides long-term reliable protection to the roll substrate under extreme environments. Thanks to the labyrinthine barrier layer formed by glass flakes and mica powder, as well as the cathodic protection mechanism, the pre-film protective layer of this application can withstand temperatures of 60°C, relative humidity of 90%, and chloride ion content of 0.1 mg / m³. 3 In extremely accelerated corrosion environments, it can provide over 840 hours of zero-rust protection for the roll substrate. After removing the pre-film protective layer, there are no rust spots or pitting marks on the roll substrate surface. This protective durability far exceeds the technical level of traditional rust-preventive oils (which fail within days to weeks) and simple coatings (which fail within weeks), ensuring the rolls remain in good condition during long-term shutdowns or harsh storage conditions.

[0123] The present application will be further described below with reference to specific embodiments and comparative examples, but should not be construed as limiting the scope of protection of the present application.

[0124] Example 1:

[0125] (1) Raw materials for roll pre-filming agent

[0126] The raw materials for the roll pre-filming agent are provided according to the following formula (total mass 1.0 kg): 380 g of sodium silicate (modulus 3.2), 110 g of silica sol (SiO2 content 35wt%), 150 g of nano SiO2 (average particle size 60 nm), 60 g of α-Al2O3, 40 g of nano TiO2 (average particle size 30 nm), 35 g of nano MgO (average particle size 40 nm), 70 g of glass flakes, 50 g of mica powder (600 mesh), 35 g of sheet zinc-aluminum alloy powder (Zn:Al=85:15, D50=5μm, surface phosphate passivation treatment), 32 g of ammonium polyacrylate dispersant, 6 g of polyethylene glycol, 2 g of hydroxypropyl methylcellulose (HPMC), 12 g of silane coupling agent (epoxysiloxane oligomer, Evonik Dynasylan 1151), 3 g of silicone defoamer, and 15 g of deionized water.

[0127] (2) Preparation of pre-filming agent for rolling mill rolls

[0128] (2.1) Preparation and pre-dispersion of functional fillers

[0129] According to the above formula, nano-SiO2, nano-MgO, and nano-TiO2 were added to a planetary ball mill, with triethanolamine as the grinding aid, and milled at 250 r / min for 20 h. Al2O3 balls with diameters of 5 mm, 2 mm, and 1 mm were used as the grinding balls, with a mass ratio of 6:3:1. After milling, the powder was dried at 80℃ for 24 h and then passed through a 200-mesh sieve for later use.

[0130] Then, the α-Al2O3, flake zinc-aluminum alloy powder, glass flakes, mica powder, and the nano-oxide powder prepared by ball milling are added together to a V-type mixer and stirred continuously at 400 rpm for 25 minutes to obtain a homogeneous mixed filler.

[0131] (2.2) Preparation of composite inorganic binder

[0132] Sodium silicate and silica sol were mixed, and the prescribed amount of silane coupling agent was added. The mixture was stirred at 200 r / min for 20 min to ensure that all components were fully homogeneous, thus obtaining a composite inorganic binder base liquid.

[0133] (2.3) Formulation of organic dispersants and water-retaining agents

[0134] Ammonium polyacrylate, polyethylene glycol, and hydroxypropyl methylcellulose were mixed according to the formula, and deionized water was added. The mixture was stirred at 200 r / min for 20 min to obtain an organic dispersion and water-retaining agent solution.

[0135] (2.4) Preparation of pre-filming agent slurry for rolls

[0136] The mixed filler was slowly added to the composite inorganic binder base liquid under slow stirring at 200 rpm. At the same time, the formula amount of defoamer and the above-mentioned organic dispersant and water-retaining agent solution were added. After the addition was completed, the mixture was sheared and stirred at 1200 rpm for 30 minutes to ensure that the components were fully and evenly dispersed. After standing and defoaming, the roll pre-filming agent slurry was obtained.

[0137] (3) Preparation of pre-film protective layer

[0138] The pre-filming agent slurry was applied in three coats to the surface of a steel roll substrate sample pretreated with anhydrous ethanol using pneumatic spraying. The air pressure was 0.5 MPa, the spraying angle was 40°, and the spraying distance was 250 mm. The wet film thickness of each coat was controlled between 100 μm and 150 μm, with a 15-minute interval between coats for surface drying. The total dry film thickness was controlled to be approximately 300 μm. The roll was then allowed to air dry at room temperature (25°C, RH 50%) for 72 hours to obtain a roll with a pre-filming protective layer.

[0139] The surface roughness Ra of the pre-film protective layer was measured to be 14.6 μm, and the adhesion strength (pull-off method) between the pre-film protective layer and the roll substrate was 6.0 MPa. Under simulated steel-passing conditions (contact stress 30 MPa), the pre-film protective layer underwent uniform fragmentation, with the fragment particle size mainly distributed in the range of 60 μm to 120 μm. At 60℃, RH 90%, and Cl... - 0.1 mg / m 3 In the accelerated corrosion test, after 840 hours, the pre-film protective layer was removed, and there were no traces of rust or pitting on the surface of the roll substrate.

[0140] Example 2:

[0141] This embodiment is basically the same as Embodiment 1, except that:

[0142] In step (1), the formula of the pre-filming agent for the roll is adjusted as follows: 400g of potassium silicate (modulus 3.0), 90g of silica sol, 130g of nano SiO2, 80g of α-Al2O3, 35g of nano TiO2, 40g of nano MgO, 80g of glass flakes, 60g of mica powder, 30g of flaky zinc powder (D50=8μm, with silane coating on the surface), and the remaining additives are the same as in Example 1.

[0143] In step (3), after spraying the wet film, the curing is accelerated by drying in a 60°C oven for 20 hours.

[0144] The pre-film protective layer in the prepared roll has a thickness of approximately 350 μm, a surface roughness Ra = 13.8 μm, and an adhesion strength between the pre-film protective layer and the roll substrate of 6.5 MPa. In the same accelerated corrosion test, the roll substrate was protected for over 900 hours. In the steel-passing simulation test, the pre-film protective layer showed uniform pulverization under a contact stress of 30 MPa, with no abnormal large-scale peeling.

[0145] Example 3:

[0146] This embodiment is basically the same as Embodiment 1, except that:

[0147] In step (1), the formula of the pre-filming agent for the rolls is adjusted as follows: 350g of potassium silicate (modulus 3.5), 130g of silica sol, 170g of nano SiO2, 50g of α-Al2O3, 50g of nano TiO2, 30g of nano MgO, 60g of glass flakes, 40g of mica powder, 40g of flaky zinc-aluminum alloy powder (Zn:Al=90:10, D50=3μm), and the remaining additives are the same as in Example 1.

[0148] In step (3), a high-hardness alloy cast iron roll substrate is used. After the roll pre-filming agent is sprayed onto the surface of the roll substrate, it is dried at room temperature for 96 hours.

[0149] The pre-film protective layer in the prepared roll has a thickness of approximately 260 μm, a surface roughness Ra = 15.2 μm, and an adhesion strength between the pre-film protective layer and the roll substrate of 6.8 MPa. In the simulated steel-passing test, the pre-film protective layer under a contact stress of 30 MPa exhibits uniform fragmentation, which is beneficial for the formation of a sliding friction layer between the roll and the red steel interface.

[0150] Comparative Example 1:

[0151] This comparative example is basically the same as Example 1, except that the silica sol is replaced with an equal mass of deionized water, while the rest of the formulation and process are the same as in Example 1.

[0152] After drying at room temperature, fine cracks appeared on the surface of the pre-filmed protective layer, and its water resistance decreased significantly. After being placed in a RH90% environment for 480 hours, the pre-filmed protective layer locally blistered and powdered. After removing the pre-filmed protective layer, slight rust spots appeared on the surface of the roll substrate. This indicates that a single water glass system is insufficient to meet the requirements of the humid environment of the rolling mill in terms of resistance to damp heat and cracking resistance.

[0153] Comparative Example 2:

[0154] This comparative example is basically the same as Example 1, except that the glass flakes and mica powder are omitted and replaced with an equal mass of SiO2, while the rest of the formulation is the same as in Example 1.

[0155] The density of the pre-film protective layer decreased, and rust spots appeared after 600 hours in the accelerated corrosion test. In the steel simulation test, the pre-film protective layer did not break along the layered interface after being compressed, but instead produced random cracks and large fragments. The size distribution of the fragments was extremely uneven (from fine powder to fragments of several millimeters), and it could not effectively and uniformly fill the roll-red steel interface, resulting in poor simulated bite conditions.

[0156] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0157] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A pre-filming agent for rolling mills, characterized in that, The composition by mass percentage includes: 30%–45% water glass, 8%–15% silica sol, 0.5%–2% silane coupling agent, 10%–20% nano silica, 3%–8% micron α-Al₂O₃, 2%–6% nano titanium dioxide, 2%–5% nano magnesium oxide, 5%–10% glass flakes, 3%–7% mica powder, 2%–5% flaky zinc-based active filler, 3%–6% organic dispersant and water-retaining agent, 0.1%–0.5% defoamer, with the balance being deionized water.

2. The roll pre-filming agent according to claim 1, characterized in that, The composition by mass percentage includes: 35%–40% water glass, 10%–12% silica sol, 1%–1.5% silane coupling agent, 12%–16% nano silica, 4%–6% micron α-Al₂O₃, 3%–5% nano titanium dioxide, 3%–4% nano magnesium oxide, 6%–8% glass flakes, 4%–6% mica powder, 3%–4% flaky zinc-based active filler, 4%–5% organic dispersant and water-retaining agent, 0.2%–0.3% defoamer, with the balance being deionized water.

3. The roll pre-filming agent according to claim 1, characterized in that, Meet one or more of the following: (1) The mass ratio of the water glass to the silica sol is (3~5):1; (2) Based on the total mass of the roll pre-filming agent, the sum of the mass percentages of the nano-silica, the micron-sized α-Al2O3, the nano-titanium dioxide, and the nano-magnesium oxide is 20%~35%; (3) Based on the total mass of the pre-filming agent of the roll, the sum of the mass percentages of the glass flakes and the mica powder is 8%~17%.

4. The roll pre-filming agent according to any one of claims 1 to 3, characterized in that, Meet one or more of the following: (1) The water glass includes one or more of sodium water glass and potassium water glass; (2) The modulus of the water glass is 2.8~3.5; (3) The mass fraction of silica in the silica sol is 30%~40%; (4) The particle size of silica in the silica sol is 10 nm to 50 nm; (5) The silane coupling agent is an oligomer type silane coupling agent, which includes epoxy siloxane oligomers.

5. The roll pre-filming agent according to any one of claims 1 to 3, characterized in that, Meet one or more of the following: (1) The average particle size of the nano-silica is 30nm~80nm; (2) The average particle size of the micron-sized α-Al2O3 is 0.5 μm to 5 μm; (3) The average particle size of the nano-titanium dioxide is 20nm~50nm; (4) The average particle size of the nano-magnesium oxide is 30nm~60nm.

6. The roll pre-filming agent according to any one of claims 1 to 3, characterized in that, Meet one or more of the following: (1) The glass flakes have a diameter of 80 mesh to 120 mesh and a thickness of 2 μm to 10 μm; (2) The particle size of the mica powder is 400 mesh to 800 mesh, and the aspect ratio is greater than 50; (3) The sheet-like zinc-based active filler is a zinc sheet or a zinc-aluminum alloy sheet, and the D50 particle size of the sheet-like zinc-based active filler is 2μm~10μm; (4) The organic dispersant and water-retaining agent is a mixture of ammonium polyacrylate, polyethylene glycol and hydroxypropyl methylcellulose.

7. A method for preparing a pre-filming agent for rolls according to any one of claims 1 to 6, characterized in that, Includes the following steps: Nano-silica, nano-titanium dioxide and nano-magnesium oxide are mixed and ball-milled to obtain oxide powder; Micron-sized α-Al2O3, glass flakes, mica powder, flaky zinc-based active filler, and the oxide powder are mixed to obtain a mixed filler; Water glass, silica sol and silane coupling agent are mixed to obtain a composite inorganic binder base liquid; The organic dispersant and water-retaining agent were mixed with deionized water to obtain an organic dispersant and water-retaining agent solution; The organic dispersion is mixed with the water-retaining agent solution, the mixed filler, the composite inorganic binder base liquid and the defoamer to obtain the roll pre-filming agent.

8. A rolling mill roll, characterized in that, It includes a roll substrate and a pre-film protective layer, wherein the pre-film protective layer is disposed on at least a portion of the surface of the roll substrate, and the pre-film protective layer is obtained by drying and curing the roll pre-filming agent according to any one of claims 1 to 6.

9. The roll according to claim 8, characterized in that, Meet one or more of the following: (1) The thickness of the pre-film protective layer is 300μm~500μm; (2) The surface roughness Ra of the pre-film protective layer is greater than or equal to 12.5 μm; (3) The interfacial bonding strength between the pre-film protective layer and the roll substrate is greater than or equal to 5 MPa; (4) The cohesive strength of the pre-film protective layer is less than or equal to 25 MPa; (5) The material of the roll matrix includes one or more of hot work die steel, alloy cast iron, high speed steel and cemented carbide.

10. A method for preparing a rolling mill roll according to claim 8 or 9, characterized in that, The process includes the following steps: applying the roll pre-filming agent according to any one of claims 1 to 6 to the surface of the roll substrate to form a wet film; and drying and curing the wet film to form a pre-filming protective layer.