Coating for prolonging service life of roll shaft and coating method thereof

Abstract

The invention discloses a coating for prolonging the service life of a roll shaft and a coating method thereof. The coating is prepared from the following components in parts by weight: 45 to 62 parts of polyurethane acrylate prepolymer, 20 to 25 parts of fluoroolefin-vinyl ether copolymer, 5 to 8 parts of trimethylolpropane triacrylate, 3 to 5 parts of metal nanowire, 3 to 5 parts of 2-hydroxy-2-methyl-1-phenyl-1-acetone, 5 to 8 parts of nano inorganic filler, 0.1 to 0.3 part of flatting agent, 0.5 to 1 part of dispersing agent and 0.5 to 1 part of defoaming agent. The coating disclosed by the invention can prevent the chamfer of the roll shaft from being rusted and avoid the increase of a stress concentration coefficient, so that the phenomena of cracks and fractures of the roll shaft due to the reason are avoided.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and in particular to a coating for increasing the service life of a roller and a coating method thereof. Background Art

[0002] The high-speed wire mill roll box is the core unit of high-speed wire rod production and plays a vital role in product quality and output. Each roll box is equipped with two rollers to squeeze and roll the steel passing through. Because the rollers are used to transmit large forces and withstand heavy loads, they are made of 17CrNiMo6 steel grade according to the German DINI7210-(86) standard. After carburizing, quenching, and low-temperature tempering, they are used to achieve high strength and toughness in the core and high hardness, wear resistance, and fatigue resistance in the surface.

[0003] When water enters the roll box, it corrodes the rolls. The chamfers of the rolls are stress-concentrated areas. When water corrosion creates dense rust pits, the roughness increases, increasing the stress concentration factor. Under heavy loads, these chamfers are prone to cracking, and in severe cases, the rolls can break. This problem can have serious consequences for steel production: entire production lines can be shut down, impacting steel output. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide a coating that increases the service life of the roller, prevents rust from occurring at the chamfers of the roller, avoids an increase in the stress concentration factor, and thus avoids the occurrence of cracks and breakages in the roller due to these reasons.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a coating for increasing the service life of a roller, comprising the following components in parts by weight:

[0007] 45-62 parts of polyurethane acrylate prepolymer,

[0008] 20-25 parts of fluoroolefin-vinyl ether copolymer,

[0009] 5-8 parts of trimethylolpropane triacrylate,

[0010] 3-5 parts of metal nanowires,

[0011] 3-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone,

[0012] 5-8 parts of nano inorganic filler,

[0013] 0.1-0.3 parts of leveling agent,

[0014] Dispersant 0.5-1 part,

[0015] 0.5-1 part of defoaming agent.

[0016] Preferably, the coating for increasing the service life of the roller further comprises 1-2 parts of ethyl benzophenone.

[0017] Preferably, the reactive diluent is trimethylolpropane triacrylate.

[0018] Preferably, the metal nanowires are silver nanowires.

[0019] Preferably, the nano inorganic filler is nano SiO2.

[0020] Preferably, the leveling agent is polyether modified silicone EFKA-3777.

[0021] Preferably, the dispersant is polyether-modified silicone.

[0022] Preferably, the defoaming agent is a mineral oil-based compound.

[0023] The present invention also provides a method for applying the coating for increasing the service life of the roller, comprising the following steps:

[0024] (1) mixing all components of the coating for increasing the service life of the roller, stirring at a speed of 1000-2000 rpm for 15-20 minutes, and then performing vacuum degassing treatment;

[0025] (2) The unground roller chamfered surface at the shoulder end is subjected to laser texturing to achieve a roughness Ra of 0.8-1.5 μm.

[0026] (3) Use a cleaning agent to clean the chamfered surface of the roller to be sprayed;

[0027] (4) Place the roller treated in step (3) on a CNC spraying device, spray while the roller rotates, and control the roller speed to 10-15 rpm; maintain the distance between the spray gun and the workpiece at 20-30 cm; maintain the spray pressure at 0.3-0.5 MPa, and the coating thickness is 0.15-0.20 mm;

[0028] (5) The sprayed coating is UV cured and the effective spraying area is irradiated with UV light with a wavelength of 330-380 nm and a light intensity of 1000-1500 mW / cm 2 , the temperature is controlled at 35-40℃.

[0029] The UV curing reaction process of the coating of the present invention is as follows:

[0030] (1) Photoinitiation stage

[0031] ① Light source excitation: Ultraviolet light (365-400nm) irradiates the photoinitiator to generate active free radicals.

[0032] ② Chain initiation: Active free radicals react with acrylate double bonds, opening the double bonds to form primary free radicals.

[0033]

[0034] (2) Chain growth and cross-linking

[0035] ① Molecular chain extension: Primary free radicals react with adjacent acrylate double bonds to form long-chain free radicals.

[0036]

[0037] ② Cross-linking formation: multiple long-chain free radicals are connected to each other to form a three-dimensional network structure.

[0038]

[0039] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0040] (1) The coating of the present invention forms a three-dimensional network cross-linked structure through UV curing polymerization, thereby enhancing the mechanical interlocking effect with the substrate. The coating utilizes the physical characteristics of the coating film being almost pore-free to thoroughly seal the application surface, and can form a surface coating with excellent adhesion and almost pore-free on the substrate surface. After curing, the paint film is dense and has high adhesion to the substrate, and can prevent the invasion of moisture, chemicals, acids, alkalis, oils and salts. In order not to affect the coating's absorption of light and to form a conductive network, dispersed silver nanowires are added to inhibit electrochemical corrosion. In addition, in order to prevent the polyurethane acrylate from material degradation under high-temperature hydraulic oil, 20-25 parts of fluoroolefin-vinyl ether copolymer are added to form an oleophobic barrier to slow down material degradation when the coating is in a hydraulic oil environment of 60-100°C. The fluoroolefin-vinyl ether copolymer has a high refractive index, which can improve the light scattering efficiency inside the coating and promote deep UV curing. The coating of the present invention can prevent rust from occurring at the chamfer of the roller, avoid increasing the stress concentration factor, and thus avoid the phenomenon of cracks and breakage of the roller due to these reasons.

[0041] (2) After the coating is applied, the coating of the present invention is dense, stable, acid-resistant, alkali-resistant, salt spray-resistant, friction-resistant, high-temperature-resistant, electrochemical corrosion-resistant, and oil-resistant; it has high adhesion, high elongation, and good impact resistance; it has good leveling properties and is easy to construct; it has a high solid content and a high coating rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of a roller according to an embodiment of the present invention.

[0043] Figure 2 Schematic diagram of the three-dimensional network cross-linked structure of the coating according to an embodiment of the present invention.

[0044] Figure 3 This is the result of a fluorescent magnetic particle nondestructive testing of a roller shaft without coating on the chamfered corners according to an embodiment of the present invention after 12 months of use.

[0045] Figure 4 This is the result of a roller with oil-sprayed coating on the chamfer of an embodiment of the present invention being used for 24 months, after which the surface coating was removed and then tested by fluorescent magnetic particle nondestructive testing. DETAILED DESCRIPTION

[0046] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0047] Example 1

[0048] The coating for increasing the service life of the roller in this embodiment includes, by weight, 50 parts of a polyurethane acrylate prepolymer, 23 parts of a fluoroolefin-vinyl ether copolymer (oil-resistant and anti-degradation), 7 parts of trimethylolpropane triacrylate (reactive diluent), 5 parts of dispersed silver nanowires (conductive), 5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone (photoinitiator), 2 parts of ethyl benzophenone (co-initiator), 6 parts of nano-SiO2 (filler), 0.2 parts of polyether-modified siloxane EFKA-3777 (leveling agent), 1 part of a polyether-modified organosilicon (dispersant), and 0.8 parts of a mineral oil-based compound (defoaming agent).

[0049] Wherein, the polyurethane acrylate prepolymer is prepared from the following raw materials:

[0050] Basic reaction raw materials: toluene diisocyanate (TDI, C6H3(CH3)2NCO) content 30%, polytetramethylene ether glycol (PTMG, HO-(CH2)4-O-(CH2)4-O-) content 25%, 2-hydroxyethyl acrylate (HEA, CH2=CHCOOCH2CH2OH) content 22%.

[0051] Auxiliary raw materials: dibutyltin dilaurate (DBTDL, (C4H9)2Sn(C 17 H 35 COO)2) content is 0.07%, acetone (CH3COCH3) content is 22.9%, and hydroquinone (HQ, C6H4(OH)2) content is 0.03%.

[0052] The synthesis principle of polyurethane acrylate prepolymer is:

[0053] 1. Preparation of polyurethane prepolymer: Polyisocyanate (NCO group) and polyol (OH group) undergo a stepwise addition reaction to generate a polyurethane prepolymer with terminal isocyanate group (-NCO);

[0054] 2. Acrylation reaction: The terminal -NCO group of the polyurethane prepolymer reacts with the hydroxyl-containing acrylate monomer (-OH group) to generate a PUA prepolymer containing an acrylate double bond (C=C).

[0055] Among them, the mineral oil-based complex contains the following ingredients: paraffin oil 69%, silicon dioxide 15%, Tween-80 emulsifier 10%, xanthan gum 5.5%, and preservative kason 0.5%.

[0056] The coating method for increasing the service life of a roller in this embodiment includes the following steps:

[0057] (1) mixing all components of the coating for increasing the service life of the roller, stirring at a speed of 1000-2000 rpm for 15-20 minutes, and then performing a vacuum degassing treatment to eliminate bubbles;

[0058] (2) Laser roughening treatment is used to treat the unground roller chamfered surface 1 (such as Figure 1 Laser texturing (as shown in the figure) utilizes the high brightness of the laser beam to achieve a very high energy density on the chamfered surface. This heats, melts, and partially vaporizes the surface at the laser focus point, forming a texturing point. This results in a uniform and stable chamfered surface roughness, with the surface roughness Ra controlled within a range of 0.8-1.5 μm. This increased roughness improves the corrosion resistance of the roller chamfer and facilitates spray paint adhesion.

[0059] (3) Place the roller treated in step (2) on a CNC spraying device, spray while the roller rotates, and control the roller speed to 10-15 rpm; keep the spray gun 20-30 cm away from the workpiece; maintain the spray pressure at 0.3-0.5 MPa, and the coating thickness at 0.15-0.20 mm;

[0060] (4) The sprayed coating is UV cured and the effective spraying area is irradiated with UV light with a wavelength of 330-380 nm and a light intensity of 1000-1500 mW / cm 2 , the temperature is controlled at 35-40℃.

[0061] The coating of this embodiment forms a three-dimensional network cross-linked structure (such as Figure 2) to enhance the mechanical interlocking effect with the substrate. This coating relies on the almost pore-free physical characteristics of the coating film to thoroughly seal the application surface, forming a surface coating with excellent adhesion and almost no pores on the substrate surface. After curing, the paint film is dense and has high adhesion to the substrate, which can prevent the intrusion of moisture, chemicals, acids, alkalis, oils and salts. In order not to affect the coating's absorption of light and form a conductive network, dispersed silver nanowires are added to inhibit electrochemical corrosion. In addition, when the coating is exposed to a hydraulic oil environment of 60-100°C, to prevent the polyurethane acrylate from degrading under high-temperature hydraulic oil, 20-25 parts of fluoroolefin-vinyl ether copolymer are added to form an oleophobic barrier to slow down material degradation. Fluoroolefin-vinyl ether copolymer has a high refractive index, which can improve the light scattering efficiency within the coating and promote deep UV curing.

[0062] The coating density prepared in this embodiment is 2.3-2.5g / cm 3 After curing, the porosity is less than 1%, it can withstand 50% sulfuric acid for 260 hours, 10% sodium hydroxide for 100 hours, electrochemical corrosion for 100 hours, the swelling rate is less than 2% after immersion in mineral oil for 1000 hours, and the elongation detected at room temperature is greater than 79%.

[0063] The coating prepared in this example passed the salt spray test and achieved no red rust after 500 hours as per GB / T 10125-2021. Adhesion testing achieved Level 0 under the GB / T 9286-2021 cross-cut test. Thermal shock resistance showed no cracking after 100 cycles from -50°C to 250°C. This coating material possesses numerous properties that prevent dense corrosion pits from forming on chamfered corners.

[0064] Roller boxes often corrode and crack within 12 months when using the original rollers to roll steel. After 12 months of use, the rollers without coating at the chamfers were inspected for cracks on the surface using fluorescent magnetic particle nondestructive testing. The results showed that circumferential cracks existed along the entire chamfer. Figure 3 The roller with the coating of this embodiment sprayed on the chamfer was tested by fluorescent magnetic powder nondestructive testing after 24 months of use, and no cracks were found. Figure 4 shown.

[0065] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A coating for increasing the service life of a roller, characterized in that: Calculated by weight, it includes the following components: 45-62 parts of polyurethane acrylate prepolymer, 20-25 parts of fluoroolefin-vinyl ether copolymer, 5-8 parts of trimethylolpropane triacrylate, 3-5 parts of metal nanowires, 3-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 5-8 parts of nano inorganic filler, 0.1-0.3 parts of leveling agent, Dispersant 0.5-1 part, 0.5-1 part of defoaming agent.

2. The coating for increasing the service life of a roller according to claim 1, characterized in that: Also included is 1-2 parts of ethyl benzophenone.

3. The coating for increasing the service life of a roller according to claim 1, characterized in that: The active diluent is trimethylolpropane triacrylate.

4. The coating for increasing the service life of a roller according to claim 1, characterized in that: The metal nanowires are silver nanowires.

5. The coating for increasing the service life of a roller according to claim 1, characterized in that: The nano inorganic filler is nano SiO2.

6. The coating for increasing the service life of a roller according to claim 1, characterized in that: The leveling agent is polyether modified siloxane EFKA-3777.

7. The coating for increasing the service life of a roller according to claim 1, characterized in that: The dispersant is polyether-modified silicone.

8. The coating for increasing the service life of a roller according to claim 1, characterized in that: The defoamer is a mineral oil-based compound.

9. The coating method for increasing the service life of a roller according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) mixing all components of the coating for increasing the service life of the roller, stirring at a speed of 1000-2000 rpm for 15-20 minutes, and then performing vacuum degassing treatment; (2) The unground roller chamfered surface at the shoulder end is subjected to laser texturing to achieve a roughness Ra of 0.8-1.5 μm. (3) Use a cleaning agent to clean the chamfered surface of the roller to be sprayed; (4) Place the roller treated in step (3) on a CNC spraying device, spray while the roller rotates, and control the roller speed to 10-15 rpm; maintain the distance between the spray gun and the workpiece at 20-30 cm; maintain the spray pressure at 0.3-0.5 MPa, and the coating thickness is 0.15-0.20 mm; (5) The sprayed coating is UV cured and the effective spraying area is irradiated with UV light with a wavelength of 330-380 nm and a light intensity of 1000-1500 mW / cm 2 , the temperature is controlled at 35-40℃.

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