Acrylic resins and their preparation methods and applications, low-friction acrylic coatings and their applications, low-friction acrylic coatings and their preparation methods and applications

Abstract

This invention belongs to the technical field of lubricating functional materials, specifically relating to acrylic resins and their preparation methods and applications, low-friction acrylic coatings and their applications, and low-friction acrylic coatings and their preparation methods and applications. This invention provides an acrylic resin hydrolyzed under weakly alkaline conditions, a low-friction acrylic coating comprising the acrylic resin hydrolyzed under weakly alkaline conditions with degradable properties, and a low-friction acrylic coating comprising the low-friction acrylic coating with degradable properties and characterized by step-by-step controllable hydrolysis at the interface. The low-friction acrylic coating with degradable properties formed by the low-friction acrylic resin hydrolyzed under weakly alkaline conditions provided by this invention exhibits controllable degradation rate, good wear resistance, and self-renewal of the wear interface.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lubricating functional materials, and particularly relates to an acrylic resin, a preparation method and application thereof, a low-friction acrylic coating and application thereof, and a low-friction acrylic coating layer, a preparation method and application thereof. BACKGROUND

[0002] Lubricating materials with low friction coefficient and good wear resistance are an effective way to solve typical wear problems in the fields of mechanical friction and biological lubrication. In particular, the design of an ultra-low friction system is of great significance to the fields of energy environment and mechanical transportation. Due to the inevitable wear behavior, it is particularly important to realize a long-life wear-resistant material with low friction characteristics. For example, Aizenberg et al. of Harvard University in the United States reported a super-slippery liquid-infused porous surface (SLIPS), which locks or injects lubricating liquid into a porous substrate through a porous material, so that the surface has a low friction coefficient due to the dynamic replenishment of the lubricating liquid film under long-term service conditions. Moreover, the continuous sacrifice of this lubricating interface under wear conditions is instantaneously replenished due to the continuous leakage of the lubricating oil components, which can ensure more persistent low-friction characteristics. In addition, Chinese Patent 202011158727.4 reports a silicon oil-containing lubricating coating with a low friction coefficient, which uses a low-molecular-weight silicon oil and a polyurethane resin to construct a room-temperature solid-liquid separation coating. Under the stimulation of friction movement, the silicon oil lubricating components are released in a controllable manner, reducing the friction coefficient and prolonging the wear period. Chinese Patent 201910735154.8 reports a preparation method of a self-lubricating coating with an ultra-low friction coefficient composed of lubricant capsules and reinforcing phases. Similarly, the lubricating components are continuously leaked during the friction process to realize the construction of a wear-resistant lubricating system with low friction characteristics. However, the above-mentioned lubricating coatings do not have the characteristics of green environmental protection.

[0003] Further, the increasing environmental problems highlight the development of green and environmentally friendly low-friction systems. The principle of natural joint lubrication shows that the combination of a highly hydrated interface and a high-load-bearing substrate can ensure the characteristics of high-load-bearing and low-friction with long service life. The highly hydrated interface has typical water lubrication characteristics and wear resistance, and the high-load-bearing substrate exhibits good load-bearing characteristics through stress dispersion. Therefore, under the premise of green environmental protection, the preparation of a biomimetic gradient material that realizes the characteristics of strong hydration of the interface and high load-bearing of the bottom surface, the soft material-based viscoelastic material shows unique advantages.

[0004] However, the highly hydrated friction-reducing interface will irreversibly wear out under long-period service conditions, and therefore the stability and wear resistance of the soft material-based highly hydrated interface become the main factors limiting the preparation of artificial materials with the characteristics of natural joint lubrication. SUMMARY

[0005] The application aims to provide an acrylic resin and a preparation method and application thereof, a low-friction acrylic coating and an application thereof, and a low-friction acrylic coating and a preparation method and application thereof.

[0006] In order to achieve the above-mentioned purpose, the application provides the following technical scheme.

[0007] The application provides an acrylic resin hydrolyzed under weak alkaline conditions, which is polymerized from preparation raw materials including the following mass fractions:

[0008] The degradable polymerizable organosilicon monomer is 10-15 parts, the sum of the non-degradable acrylic monomer and the non-degradable acrylic ester monomer is 30-60 parts, the initiator is 1-1.5 parts, and the organic solvent is 50-75 parts.

[0009] The non-degradable acrylic ester monomer includes a first acrylic ester monomer, a second acrylic ester monomer and beta-hydroxyethyl methacrylate, the first acrylic ester monomer includes methyl methacrylate and / or ethyl acrylate, and the second acrylic ester monomer includes butyl acrylate and / or methoxyethyl methacrylate.

[0010] The structure of the degradable polymerizable organosilicon monomer is shown in formula I.

[0011]

[0012] In formula I, R1 is H or methyl.

[0013] Preferably, the non-degradable acrylic ester monomer includes methyl methacrylate, butyl acrylate and beta-hydroxyethyl methacrylate.

[0014] The mass ratio of the methyl methacrylate, the butyl acrylate, the beta-hydroxyethyl methacrylate and the non-degradable acrylic monomer is (4-8):(6-10):(8-12):(12-16).

[0015] The initiator is azobisisobutyronitrile.

[0016] The application provides a preparation method of the acrylic resin hydrolyzed under weak alkaline conditions.

[0017] The degradable polymerizable organosilicon monomer, the non-degradable acrylic monomer, the non-degradable acrylic ester monomer, the initiator and the organic solvent are mixed to obtain a mixed solution, and the mixed solution is subjected to a polymerization reaction to obtain the acrylic resin hydrolyzed under weak alkaline conditions.

[0018] Preferably, the temperature of the polymerization reaction is 85-95 DEG C; the polymerization reaction comprises the following steps:

[0019] Part of the mixed solution is subjected to a first stage polymerization reaction to obtain a pre-polymerization reaction liquid, and the reaction time of the first stage polymerization reaction is 25-40 min;

[0020] The remaining mixed solution is added dropwise to the pre-polymerization reaction liquid to perform a second stage polymerization reaction, and the acrylic resin hydrolyzed under weak alkaline conditions is obtained, the dropping speed is 0.8-1.2 mL / min, and the holding reaction time of the second stage polymerization reaction is 2-3 h after the dropping is completed.

[0021] The application provides application of the acrylic resin hydrolyzed under weak alkaline conditions in the low-friction acrylic coating with degradable characteristics.

[0022] The application provides a low-friction acrylic coating with degradable characteristics, which comprises the following components in mass fraction:

[0023] The acrylic resin hydrolyzed under weak alkaline conditions is 40-60 parts;

[0024] The wear-resistant filler is 10-15 parts;

[0025] The pigment filler is 10-15 parts;

[0026] The auxiliary agent is 1-2 parts;

[0027] The organic solvent is 15-25 parts;

[0028] The acrylic resin hydrolyzed under weak alkaline conditions is the acrylic resin hydrolyzed under weak alkaline conditions in the above technical solution or the acrylic resin hydrolyzed under weak alkaline conditions prepared by the preparation method in the above technical solution.

[0029] Preferably, the wear-resistant filler comprises precipitated barium sulfate, mica powder and brown corundum; the mass ratio of the precipitated barium sulfate, the mica powder and the brown corundum is (1-1.8):(1-1.8):(1-2);

[0030] The pigment filler comprises organic bentonite, kaolin, iron oxide red and zinc oxide; the mass ratio of the organic bentonite, the kaolin, the iron oxide red and the zinc oxide is (1-1.8):(1-1.8):(1-2):1;

[0031] The auxiliary agent comprises a wetting dispersant, a leveling agent, a defoaming agent and an anti-settling agent; the mass ratio of the wetting dispersant, the leveling agent, the defoaming agent and the anti-settling agent is (1-3):(1-2):(1-2):(1-2).

[0032] The application provides application of the low-friction acrylic coating with the degradable property in the low-friction acrylic coating with the interface gradual controllable hydrolysis property.

[0033] The application provides a low-friction acrylic coating with an interface gradual controllable hydrolysis property, which comprises the following raw materials in mass fractions: the low-friction acrylic coating with the degradable property 10-20 parts, and a crosslinking agent 0.1-0.3 parts.

[0034] The application provides a preparation method of the low-friction acrylic coating with the interface gradual controllable hydrolysis property.

[0035] The low-friction acrylic coating with the degradable property and an organic solvent are mixed to be coated on the surface of a substrate to obtain an initial wet film;

[0036] The initial wet film is dried to obtain the low-friction acrylic coating with the interface gradual controllable hydrolysis property on the surface of the substrate.

[0037] The application provides application of the low-friction acrylic coating with the interface gradual controllable hydrolysis property or the low-friction acrylic coating with the interface gradual controllable hydrolysis property prepared by the preparation method as a lubricating material in an alkaline environment.

[0038] This invention provides an acrylic resin hydrolyzed under weakly alkaline conditions, obtained by polymerization of the following raw materials in parts by weight: 10-15 parts of biodegradable polymerizable organosilicon monomer, 30-60 parts of a sum of non-degradable acrylic monomer and non-degradable acrylate monomer, 1-1.5 parts of initiator, and 50-75 parts of organic solvent; wherein the non-degradable acrylate monomer includes a first acrylate monomer, a second acrylate monomer, and β-hydroxyethyl methacrylate, the first acrylate monomer including methyl methacrylate and / or ethyl acrylate, and the second acrylate monomer including butyl acrylate and / or methoxyethyl methacrylate; the biodegradable polymerizable organosilicon monomer is an acrylate silicone monomer, the structural formula of which is shown in Formula I. In this invention, the biodegradable polymerizable organosilicon monomer and the non-degradable acrylic acid and acrylate monomers provide an acrylic resin matrix component that hydrolyzes under weakly alkaline conditions. Furthermore, the biodegradable organosilicon monomer imparts biodegradable properties to the acrylic resin, enabling the coating to exhibit stable degradation performance (degradation performance, i.e., hydrolysis performance, refers to the behavior of Si-O bond breakage in the coating under weakly alkaline conditions) in a weakly alkaline environment (pH 8-9). The degraded organosilicon monomer generates hydrophilic carboxyl groups, and simultaneously, a micron-sized porous structure appears on the surface of the degraded coating, further enhancing the self-lubricating properties of the coating. The β-hydroxyethyl methacrylate imparts crosslinking properties to the self-lubricating acrylic resin. When preparing the coating, a crosslinking agent (used in the examples) is used... Under the action of isocyanate crosslinking agents, crosslinking reactions can be achieved at room temperature, which is beneficial to improving the stability and mechanical properties of self-lubricating acrylic resin. At the same time, through the synergistic effect with the crosslinking agent, the controllable hydrolysis characteristics of the coating are ensured. The introduction of acrylic acid (i.e., non-degradable acrylic monomer) is beneficial to improving the hydrophilicity of the coating containing self-lubricating acrylic resin and is beneficial to constructing a hydration lubrication interface. The introduction of a second acrylate monomer (preferably butyl acrylate in the example) is beneficial to improving the flexibility of the self-lubricating acrylic resin and increasing the toughness of the coating. The initiator (such as azobisisobutyronitrile) is beneficial to promoting the graft copolymerization of the raw materials for preparing self-lubricating acrylic resin and improving the bonding ability between the self-lubricating acrylic resin obtained by graft copolymerization and the coated substrate.

[0039] This invention provides a low-friction acrylic coating with biodegradable properties, comprising the following components in parts by weight: 40-60 parts of acrylic resin hydrolyzed under weakly alkaline conditions; 10-15 parts of abrasion-resistant filler; 10-15 parts of pigments and fillers; 1-2 parts of additives; and 15-25 parts of organic solvent. The acrylic resin hydrolyzed under weakly alkaline conditions is either the acrylic resin hydrolyzed under weakly alkaline conditions described in the above-described technical solution or the acrylic resin hydrolyzed under weakly alkaline conditions prepared by the preparation method described in the above-described technical solution. In this invention, the abrasion-resistant filler helps improve the mechanical properties and abrasion resistance of the low-friction acrylic coating with gradually controllable interfacial hydrolysis characteristics; the additives and organic solvent help reduce the viscosity of the low-friction acrylic coating with biodegradable properties, improve film-forming performance, enhance the uniformity and continuity of the coating film, and strengthen the adhesion between the coating film and the substrate.

[0040] This invention provides a low-friction acrylic coating with stepwise controllable hydrolysis at the interface (in this invention, "hydrolysis" and "degradation" have the same meaning), comprising the following raw materials in parts by weight: 10-20 parts of the low-friction acrylic coating with degradable properties described in the above-mentioned technical solution and 0.1-0.3 parts of a crosslinking agent. The low-friction acrylic coating with stepwise controllable hydrolysis provided by this invention is formed by a crosslinking reaction between the low-friction acrylic coating with degradable properties described in the above-mentioned technical solution (including acrylic resin that can be hydrolyzed under weakly alkaline conditions, wear-resistant fillers, pigments, fillers, and additives, etc.) and the crosslinking agent. In this invention, the acrylic resin hydrolyzed under weakly alkaline conditions ensures stepwise degradation at the interface to form a water-lubricating layer. The crosslinking agent helps improve the stability and wear resistance of the coating. Simultaneously, by controlling the content of the crosslinking agent in the coating, the hydrolysis rate of the coating can be controlled, giving the coating controllable degradation characteristics. The wear-resistant filler ensures that the coating has good wear resistance. The acrylic coating prepared using these characteristics, determined by the acrylate silicon content and chemical crosslinking, forms a degradation hydration layer at the micron scale under weakly alkaline conditions. Combined with wear-resistant fillers, it exhibits a low interfacial friction coefficient and stable wear resistance. This feature combines the characteristics of friction reduction on the top surface and wear resistance on the bottom surface. Furthermore, this micron-scale hydration layer can continuously renew itself as the interface wears, exhibiting typical low-friction self-renewal characteristics. Finally, the low-friction acrylic coating with stepwise controllable hydrolysis characteristics provided by this invention has a certain fluid drag reduction efficiency.

[0041] The test results of the examples show that the low-friction acrylic coating with degradable properties obtained by hydrolyzing acrylic resin under weakly alkaline conditions provided by the present invention forms a low-friction acrylic coating with stepwise controllable hydrolysis at the interface. The coating has a grade 1 adhesion to the epoxy material and high bonding strength; the degradation rate of the coating is controllable, and the degradation rate decreases with the increase of crosslinking agent; it has good self-lubricating effect, with a friction coefficient of 0.06 to 0.12, which is low; the underwater heavy oil contact angle is 135 to 150°; and the drag reduction rate is 25 to 40%, showing excellent drag reduction performance. Attached Figure Description

[0042] Figure 1 SEM image of the low-friction acrylic coating after degradation, which has the characteristic of stepwise and controllable hydrolysis of the interface, provided as application example 3 of the present invention.

[0043] Figure 2 SEM cross-sectional image of a low-friction acrylic coating with stepwise controllable hydrolysis at the interface, provided as application example 3 of the present invention;

[0044] Figure 3 The friction coefficient curve of the low-friction acrylic coating with stepwise controllable hydrolysis at the interface provided in Application Example 3 of the present invention after degradation by a weak alkaline solution under a load of 1N and a frequency of 1Hz for 10 hours. Detailed Implementation

[0045] This invention provides an acrylic resin hydrolyzed under weakly alkaline conditions, obtained by polymerization of raw materials comprising the following parts by weight:

[0046] 10-15 parts of biodegradable polymerizable organosilicon monomers, 30-60 parts of non-biodegradable acrylic monomers and non-biodegradable acrylate monomers, 1-1.5 parts of initiator, and 50-75 parts of organic solvent (hereinafter referred to as the first organic solvent);

[0047] The non-degradable acrylate monomers include a first acrylate monomer, a second acrylate monomer, and β-hydroxyethyl methacrylate, wherein the first acrylate monomer includes methyl methacrylate and / or ethyl acrylate, and the second acrylate monomer includes butyl acrylate and / or methoxyethyl methacrylate.

[0048] The biodegradable and polymerizable organosilicon monomer is an acrylate silicone monomer, and its structural formula is shown in Formula I:

[0049]

[0050] In Formula I, R1 is H or methyl.

[0051] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0052] The acrylic resin hydrolyzed under weakly alkaline conditions provided by the present invention preferably has a pH value of 8 to 9.

[0053] The raw materials for preparing the weakly alkaline hydrolyzed acrylic resin provided by the present invention, by weight, include 10-15 parts of biodegradable polymerizable organosilicon monomer, preferably 11-14 parts, more preferably 12-13 parts, and specifically 14 parts in the examples. In the present invention, the biodegradable polymerizable organosilicon monomer is an acrylate silicone ester monomer, and the structural formula of the biodegradable polymerizable organosilicon monomer is shown in Formula I.

[0054] Based on the mass fraction of the biodegradable polymerizable organosilicon monomer, the raw materials for preparing the weakly alkaline hydrolyzable acrylic resin provided by this invention comprise 30-60 parts of non-degradable acrylic monomer and non-degradable acrylate monomer, preferably 35-45 parts, and more preferably 38-42 parts. In this invention, the non-degradable acrylic monomer can be acrylic acid. The non-degradable acrylate monomer includes a first acrylate monomer, a second acrylate monomer, and β-hydroxyethyl methacrylate. The first acrylate monomer includes methyl methacrylate and / or ethyl acrylate, and the second acrylate monomer includes butyl acrylate and / or methoxyethyl methacrylate. In this invention, the non-degradable acrylate monomer preferably includes methyl methacrylate, butyl acrylate, and β-hydroxyethyl methacrylate. The preferred mass ratio of methyl methacrylate, butyl acrylate, β-hydroxyethyl methacrylate, and non-degradable acrylic monomer is (4-8):(6-10):(8-12):(12-16), more preferably (5-8):(8-10):(10-12):(12-16), and even more preferably (4.5-5.5):(7-9):(9-11):(13-15) or (6-7):(8.5-9.5):(10.5-11.5):(14-15).

[0055] In embodiments of the present invention, the non-degradable acrylate monomers are specifically methyl methacrylate, butyl acrylate, and β-hydroxyethyl methacrylate. Based on the mass fraction of the degradable polymerizable organosilicon monomers, the raw materials for the weakly alkaline hydrolyzable acrylic resin provided by the present invention include 6 parts methyl methacrylate, 8 parts butyl acrylate, 10 parts β-hydroxyethyl methacrylate, and 14 parts acrylic acid.

[0056] Based on the mass fraction of the biodegradable polymerizable organosilicon monomer, the raw materials for preparing the weakly alkaline hydrolyzed acrylic resin provided by the present invention include 1 to 1.5 parts of initiator, preferably 1.1 to 1.4 parts, more preferably 1.2 to 1.3 parts, and specifically 1.5 parts in the examples. In the present invention, the initiator is preferably azobisisobutyronitrile (AIB).

[0057] Based on the mass fraction of the biodegradable polymerizable organosilicon monomer, the raw materials for preparing the weakly alkaline hydrolyzed acrylic resin provided by this invention include 50-75 parts of a first organic solvent, preferably 52-68 parts, more preferably 55-65 parts, and specifically 75 parts in the examples. In this invention, the first organic solvent is preferably xylene and N,N-dimethylformamide. The mass ratio of xylene to N,N-dimethylformamide is preferably (1-2):(1-2), more preferably (1-1.5):(1-1.5). This invention does not specifically limit the preparation method of the first organic solvent; the components of the organic solvent can be directly mixed.

[0058] In this invention, the acrylic resin hydrolyzed under weakly alkaline conditions is obtained by polymerizing a biodegradable polymerizable organosilicon monomer, non-degradable acrylic acid, and non-degradable acrylate compounds; the acrylic resin hydrolyzed under weakly alkaline conditions has the structure shown in Formula II:

[0059]

[0060] In Formula II, R1 is -H or methyl.

[0061] This invention provides a method for preparing acrylic resin hydrolyzed under weakly alkaline conditions as described in the above technical solution, comprising the following steps:

[0062] A biodegradable polymerizable organosilicon monomer, a non-biodegradable acrylic monomer, a non-biodegradable acrylate monomer, an initiator, and a first organic solvent are mixed to obtain a mixed solution; the mixed solution is subjected to a polymerization reaction to obtain the acrylic resin hydrolyzed under weakly alkaline conditions.

[0063] In this invention, the mixing sequence preferably includes: dissolving the initiator in a first organic solvent to obtain an initiator solution; and stirring and mixing the initiator solution, a biodegradable polymerizable organosilicon monomer, a non-biodegradable acrylic monomer, and a non-biodegradable acrylate monomer to obtain a mixed solution. The dissolution is preferably carried out under stirring conditions.

[0064] In this invention, the polymerization reaction temperature is preferably 85–95°C, more preferably 87–93°C, and even more preferably 88–92°C. In a specific embodiment of this invention, the polymerization reaction is carried out in a three-necked flask. In this invention, the polymerization reaction preferably includes the following steps:

[0065] A portion of the mixed solution is subjected to a first-stage polymerization reaction to obtain a prepolymerized reaction solution. In this invention, the percentage of the mixed solution by mass of the portion thereof is preferably 25-35 wt.%, specifically 30 wt.%. The reaction time of the first-stage polymerization reaction is preferably 25-40 min, more preferably 25-35 min, and even more preferably 28-32 min.

[0066] After obtaining the prepolymerization reaction solution, the present invention adds the remaining mixed solution dropwise to the prepolymerization reaction solution to carry out a second-stage polymerization reaction, thereby obtaining the acrylic resin hydrolyzed under weakly alkaline conditions. In the present invention, the percentage of the remaining mixed solution in the total mass of the mixed solution is preferably 65-75 wt.%, specifically 70 wt.%. The dropping rate is preferably 0.8-1.2 mL / min, more preferably 0.9-1.1 mL / min. In the present invention, the dropping is preferably carried out under stirring conditions, the stirring is preferably mechanical stirring, and the stirring rate is preferably 200-400 rpm, more preferably 220-380 rpm. After the dropping is completed, the holding time for the second-stage polymerization reaction is preferably 2-3 h, more preferably 2.3-2.8 h, and more preferably 2.4-2.8 h.

[0067] In this invention, the solid content of the acrylic acid hydrolyzed under weakly alkaline conditions is preferably 35-45%, more preferably 38-42%, and even more preferably 39-41%.

[0068] This invention provides the application of the acrylic resin hydrolyzed under weakly alkaline conditions as described in the above-described technical solution, or the acrylic resin hydrolyzed under weakly alkaline conditions prepared by the preparation method described in the above-described technical solution, in low-friction acrylic coatings with degradable properties.

[0069] In this invention, the acrylic resin hydrolyzed under weakly alkaline conditions is used as the raw material for preparing the low-friction acrylic coating with degradable properties.

[0070] This invention provides a low-friction acrylic coating with biodegradable properties, comprising the following components in parts by weight:

[0071] 40-60 parts of acrylic resin hydrolyzed under weakly alkaline conditions;

[0072] 10-15 parts of wear-resistant filler;

[0073] 10-15 parts of pigments and fillers;

[0074] 1-2 parts of auxiliary agent;

[0075] 15-25 parts of organic solvent (hereinafter referred to as the second organic solvent);

[0076] The acrylic resin hydrolyzed under weakly alkaline conditions is either the acrylic resin hydrolyzed under weakly alkaline conditions described in the above technical solution or the acrylic resin hydrolyzed under weakly alkaline conditions prepared by the preparation method described in the above technical solution.

[0077] By weight, the low-friction acrylic coating with degradable properties provided by the present invention comprises 40-60 parts, preferably 42-55 parts, more preferably 45-50 parts, of acrylic resin hydrolyzed under weakly alkaline conditions; specifically, in the examples, 60 parts, 50 parts, and 40 parts. In the present invention, the acrylic resin hydrolyzed under weakly alkaline conditions is the acrylic resin hydrolyzed under weakly alkaline conditions described in the above-described technical solution or the acrylic resin hydrolyzed under weakly alkaline conditions prepared by the preparation method described in the above-described technical solution.

[0078] Based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 10-15 parts of abrasion-resistant filler, preferably 11-14 parts, and more preferably 12-13 parts. In the present invention, the abrasion-resistant filler preferably comprises precipitated barium sulfate, mica powder, and brown fused alumina; the mass ratio of the precipitated barium sulfate, mica powder, and brown fused alumina is preferably (1-1.8):(1-1.8):(1-2), more preferably (1-1.5):(1-1.5):(1-2), further preferably (1.2-1.5):(1.2-1.5):(1.2-1.8). Most preferably (1.2-1.4):(1.2-1.4):(1.2-1.8). In the present invention, the abrasion-resistant filler is beneficial for improving the mechanical properties of the coating formed by the low-friction acrylic coating and enhancing its abrasion resistance.

[0079] In an embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 3 parts of precipitated barium sulfate, 3 parts of mica powder, and 4 parts of brown corundum.

[0080] Based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 10-15 parts of pigments and fillers, preferably 11-14 parts, and more preferably 12-13 parts. In the present invention, the pigments and fillers preferably include organobentonite, kaolin, iron oxide red, and zinc oxide; the mass ratio of organobentonite, kaolin, iron oxide red, and zinc oxide is preferably (1-1.8):(1-1.8):(1-2):1, more preferably (1-1.5):(1-1.5):(1-2):1, further preferably (1.2-1.5):(1.2-1.5):(1.2-1.8):1, and most preferably (1.2-1.4):(1.2-1.4):(1.2-1.8):1. In the present invention, the pigments and fillers are beneficial for enhancing the mechanical properties of the coating formed by the low-friction acrylic coating with degradable properties, improving the thixotropic properties of the coating, and reducing the cost of the coating.

[0081] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 2.5 parts of organic bentonite, 2.5 parts of kaolin, 4 parts of iron oxide red, and 2 parts of zinc oxide.

[0082] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 4 parts of iron oxide red, 2 parts of zinc oxide, 2.5 parts of organobentonite and 2.5 parts of kaolin.

[0083] Based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 1-2 parts of additives, preferably 1.2-1.8 parts, and more preferably 1.3-1.7 parts. In the present invention, the additives preferably include wetting and dispersing agents, leveling agents, defoamers, and anti-settling agents. Specifically, the wetting and dispersing agents are BYK163 and BYK104s, and the mass ratio of BYK163 to BYK104s is preferably 1:1. The leveling agent is preferably BYK300, BYK333, or BYK354, specifically BYK354. The defoamer is preferably BYK052 or Tiger 386N, specifically BYK052. The anti-settling agent is specifically BYK410. The preferred mass ratio of the wetting and dispersing agent, leveling agent, defoamer, and anti-settling agent is (1-3):(1-2):(1-2):(1-2), more preferably (1-2.5):(1-1.8):(1-1.8):(1-1.8) or (1.3-2.7):(1-1.5):(1-1.5):(1.2-1.8). In this invention, the additives help reduce the apparent defects of the coating formed by the low-friction self-lubricating coating, improve the surface gloss, smoothness, and flatness of the coating; at the same time, they improve the uniform dispersion of fillers in the coating system, which helps to improve the application performance of the coating, enhance the wettability of the coating formed by the low-friction self-lubricating coating to the substrate, and improve the adhesion.

[0084] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the additives in the low-friction acrylic coating with degradable properties provided by the present invention include 0.3 parts of wetting and dispersing agent BYK163, 0.3 parts of wetting and dispersing agent BYK104s, 0.3 parts of anti-settling agent BYK410, 0.25 parts of defoamer BYK052, and 0.35 parts of leveling agent BYK354.

[0085] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the additives in the low-friction acrylic coating with degradable properties provided by the present invention include 0.258 parts of wetting and dispersing agent BYK163, 0.258 parts of wetting and dispersing agent BYK104s, 0.258 parts of anti-settling agent BYK410, 0.215 parts of defoamer BYK052, and 0.3 parts of leveling agent BYK354.

[0086] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the additives in the low-friction acrylic coating with degradable properties provided by the present invention include 0.228 parts of wetting and dispersing agent BYK163, 0.228 parts of wetting and dispersing agent BYK104s, 0.228 parts of anti-settling agent BYK410, 0.19 parts of defoamer BYK052, and 0.266 parts of leveling agent BYK354.

[0087] Based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the low-friction acrylic coating with degradable properties provided by the present invention comprises 15-25 parts of a second organic solvent, preferably 17-23 parts, and more preferably 19-22 parts. In the present invention, the second organic solvent is preferably xylene, N,N-dimethylformamide, and n-butanol, and the mass ratio of xylene, N,N-dimethylformamide, and n-butanol is preferably (1-2):(1-2):(1-2), more preferably (1.2-1.8):(1.2-1.8):(1.2-1.8). In the present invention, the organic solvent is beneficial for improving the viscosity of the low-friction acrylic coating, enhancing the film-forming properties of the coating, and also for the application of the coating.

[0088] In a specific embodiment of the present invention, based on the mass fraction of the acrylic resin hydrolyzed under the weakly alkaline conditions, the second organic solvent in the low-friction acrylic coating with degradable properties provided by the present invention includes 5 parts xylene, 5 parts N,N-dimethylformamide and 5 parts n-butanol.

[0089] In this invention, the method for preparing the low-friction acrylic coating with biodegradable properties preferably includes the following steps:

[0090] The acrylic resin hydrolyzed under weakly alkaline conditions, additives, and a second organic solvent are mixed to obtain a preliminary mixture.

[0091] The initial mixture, abrasion-resistant filler, and pigments are mixed to obtain the low-friction acrylic coating with biodegradable properties.

[0092] In this invention, the mixing of the hydrolyzed acrylic resin, additives and organic solvent under weakly alkaline conditions is preferably carried out under stirring conditions; the stirring rate is preferably 300-400 rpm, more preferably 320-380 rpm; the stirring time is preferably 25-35 min, more preferably 27-32 min, and most preferably 30 min.

[0093] In this invention, the mixing of the initial mixture, wear-resistant filler, and pigments / fillers is preferably carried out sequentially by stirring and ball milling. In this invention, the stirring rate is preferably 500–700 rpm, more preferably 550–600 rpm; the stirring time is preferably 25–35 min, more preferably 27–32 min, and most preferably 30 min. In this invention, the ball milling speed is preferably 1500–2000 rpm, more preferably 1600–1900 rpm; the ball milling time is preferably 4–8 h, more preferably 5–6 h. In this invention, the ball-to-material ratio in the ball milling is preferably (1–4):2, more preferably (1.5–3):2. In this invention, the ball milling equipment is preferably a ball mill, more preferably a planetary ball mill. In an embodiment of this invention, the planetary ball mill is preferably model QM-3SP2. In this invention, the fineness of the low-friction acrylic coating with biodegradable properties is preferably ≤40 μm.

[0094] After ball milling, the present invention preferably filters the resulting ball-milled material to remove impurities or large particle agglomerates, ensuring the fineness of the low-friction acrylic coating with biodegradable properties.

[0095] This invention provides the application of the low-friction acrylic coating with degradable properties described above in a low-friction acrylic coating with stepwise controllable hydrolysis characteristics at the interface.

[0096] In this invention, the application specifically refers to: preparing the low-friction acrylic coating with the characteristics of stepwise and controllable hydrolysis at the interface on the surface of a substrate using a low-friction acrylic coating with degradable properties.

[0097] This invention provides a low-friction acrylic coating with stepwise controllable hydrolysis at the interface, comprising the following raw materials in parts by weight: 10-20 parts of the low-friction acrylic coating with degradable properties described in the above technical solution and 0.1-0.3 parts of a crosslinking agent.

[0098] By mass fraction, the raw materials for preparing the low-friction acrylic coating with stepwise controllable hydrolysis at the interface provided by the present invention include 10 to 20 parts, preferably 10 to 15 parts, of the low-friction acrylic coating with degradable properties described in the above technical solution, specifically 10 parts.

[0099] Based on the mass fraction of the low-friction acrylic coating with degradable properties, the raw materials for preparing the low-friction acrylic coating with stepwise controllable hydrolysis at the interface provided by the present invention include 0.1 to 0.3 parts of a crosslinking agent, preferably 0.15 to 0.25 parts, more preferably 0.15 to 0.2 parts, specifically 0.195 parts, 0.181 parts, 0.164 parts, 0.137 parts, 0.109 parts, and 0.191 parts. In the present invention, the crosslinking agent is preferably an isocyanate crosslinking agent. In the present invention, the crosslinking agent is more preferably toluene-2,4-diisocyanate and / or diphenylmethane diisocyanate.

[0100] In this invention, the amount of crosslinking agent is preferably such that the molar ratio of the isocyanate crosslinking agent to the β-hydroxyethyl methacrylate, the raw material of the acrylic resin hydrolyzed under weakly alkaline conditions in the low-friction acrylic coating with degradable properties, satisfies (0.5-1.5):1, further satisfies (0.7-1.3):1, and most preferably satisfies (0.714-1.25):1. Based on satisfying the above requirements, the low-friction acrylic coating with the characteristic of stepwise controllable hydrolysis at the interface provided by this invention comprises 10-20 parts of the low-friction acrylic coating with degradable properties as described in the above technical solution and 0.1-0.3 parts of crosslinking agent.

[0101] In this invention, the crosslinking agent facilitates the formation of a crosslinked network structure in the coating, which improves the coating's stability and mechanical properties. Furthermore, by controlling the amount of crosslinking agent, this invention controls the hydrolysis rate of the coating, imparting controllable degradation characteristics. In this invention, the amount of crosslinking agent depends on the degree of crosslinking; the degree of crosslinking is preferably 50%–70%, more preferably 55%–65%, and most preferably 60%. In the 60% crosslinking degree, the molar ratio of β-hydroxyethyl methacrylate to toluene-2,4-diisocyanate is preferably 1.2:1.

[0102] This invention provides a method for preparing a low-friction acrylic coating with stepwise controllable hydrolysis at the interface as described in the above technical solution, comprising the following steps:

[0103] The low-friction acrylic coating with degradable properties described in the above technical solution, the crosslinking agent and the organic solvent (hereinafter referred to as the third organic solvent) are mixed and coated on the surface of the substrate to obtain an initial wet film;

[0104] The initial wet milling process is dried to obtain a low-friction acrylic coating with stepwise controllable hydrolysis characteristics on the substrate surface.

[0105] This invention involves mixing a low-friction acrylic coating with degradable properties, a crosslinking agent, and an organic solvent (hereinafter referred to as the third organic solvent) as described in the above-mentioned technical solution, and then coating the mixture onto a substrate surface to obtain an initial wet film. In this invention, the preferred mass ratio of the low-friction acrylic coating with degradable properties to the third organic solvent is (10-20):(4-8), more preferably 10-15:(4-8), specifically 10:5. This invention preferably uses the third organic solvent to reduce the viscosity of the mixture formed by the low-friction acrylic coating with degradable properties and the crosslinking agent, thereby improving the film-forming performance of the diluted coating formed by the mixture of the low-friction acrylic coating with degradable properties, the crosslinking agent, and the third organic solvent on the substrate surface.

[0106] In this invention, the third organic solvent is preferably xylene, N,N-dimethylformamide and n-butanol; the mass ratio of xylene, N,N-dimethylformamide and n-butanol is preferably (1-2):(1-2):(1-2), more preferably (1-1.5):(1-1.5):(1-1.5).

[0107] In this invention, the substrate is preferably an epoxy-based material. Prior to coating, the substrate is preferably cleaned to obtain a clean substrate. The coating method is preferably spraying or brushing.

[0108] After obtaining the initial wet film, the present invention dries the initial wet milling process to obtain a low-friction acrylic coating with controllable stepwise hydrolysis characteristics on the substrate surface. In the present invention, the drying can be carried out at room temperature, and the drying time can be 24-48 hours. The present invention does not have any particular limitation on the drying process, and any drying method known to those skilled in the art can be used. The present invention forms a solid film after drying, in which most of the third organic solvent will evaporate, and perhaps a small amount will remain.

[0109] In this invention, the thickness of the low-friction acrylic coating with stepwise controllable hydrolysis at the interface is preferably 100–200 μm, more preferably 120–180 μm. In this invention, the coating amount is determined to ensure the thickness of the low-friction acrylic coating with stepwise controllable hydrolysis at the interface.

[0110] The low-friction acrylic coating with stepwise controllable hydrolysis at the interface obtained by this invention is firmly bonded to the substrate.

[0111] This invention provides the application of the low-friction acrylic coating with the characteristics of stepwise controllable hydrolysis at the interface as described in the above-described technical solution, or the low-friction acrylic coating with the characteristics of stepwise controllable hydrolysis at the interface prepared by the above-described technical solution, as a lubricating material in an alkaline environment.

[0112] In this invention, the preferred application includes applying the low-friction acrylic coating with the characteristics of stepwise controllable hydrolysis at the interface to marine engineering lubricating materials.

[0113] The low-friction acrylic coating with stepwise controllable hydrolysis at the interface provided by this invention (taking the coating prepared in Application Example 3 as an example) is shown in the SEM image of its surface after continuous immersion in a weakly alkaline solution and subsequent freeze-drying treatment. Figure 1 See cross-sectional SEM images Figure 2 Under a load of 1N and a frequency of 1Hz, the friction coefficient curve for a 10-hour long friction period is shown below. Figure 3 In this invention, the acrylic resin hydrolyzed under weakly alkaline conditions ensures the gradual degradation of the interface to form a water-lubricating layer. The chemical cross-linking structure ensures the controllable degradation of the coating, while the wear-resistant filler ensures the coating has good wear resistance. The acrylic coating prepared by these characteristics, determined by the acrylic-silicone content and chemical cross-linking, forms a degradation hydration layer at the micron scale under weakly alkaline conditions. Combined with the wear-resistant filler, it exhibits a low interfacial friction coefficient and stable wear resistance. This feature combines the characteristics of friction reduction on the top surface and wear resistance on the bottom surface. Furthermore, this micron-scale hydration layer can continuously renew itself as the interface wears, exhibiting typical low-friction self-renewal characteristics.

[0114] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0115] In the following examples, the parts are parts by weight.

[0116] Example 1

[0117] Preparation of hydrolyzed acrylic resin under weakly alkaline conditions: First, weigh 1.5 parts of azobisisobutyronitrile, 37.5 parts each of xylene and N,N-dimethylformamide into a beaker, and then stir thoroughly to completely dissolve the azobisisobutyronitrile. Next, weigh 6 parts of methyl methacrylate, 8 parts of butyl acrylate, 10 parts of β-hydroxyethyl methacrylate, 12 parts of triisopropylsilyl acrylate, and 14 parts of acrylic acid into a beaker and stir thoroughly to obtain a mixture solution. Then, weigh 30% of the mixture solution into a flask and react it at 90℃ with mechanical stirring for 30 min. After that, add the remaining 70% of the mixture solution into the flask at a dropping rate of 1.0 mL / min. After the addition is complete, continue to keep warm for 2 h to carry out the polymerization reaction, and obtain a hydrolyzed acrylic resin with a solid content of 40% under weakly alkaline conditions.

[0118] Example 2

[0119] By weight, 60 parts of the weakly alkaline hydrolyzed acrylic resin obtained in Example 1, 0.3 parts of wetting and dispersing agent BYK163, 0.3 parts of wetting and dispersing agent BYK104s, 0.3 parts of anti-settling agent BYK410, 0.25 parts of defoamer BYK052, 0.35 parts of leveling agent BYK354, 5 parts of xylene, 5 parts of N,N-dimethylformamide, and 5 parts of n-butanol were mixed evenly to obtain a preliminary mixture; the obtained preliminary mixture, 3 parts Precipitated barium sulfate, 3 parts mica powder, 4 parts brown corundum, 4 parts iron oxide red, 2 parts zinc oxide, 2.5 parts organobentonite, and 2.5 parts kaolin were mixed and dispersed at 300 rpm for 30 min. Then, a QM-3SP2 planetary ball mill was used to ball mill the mixture at 3000 rpm for 6 h. After discharge, the mixture was filtered to obtain a low-friction acrylic coating with a solid content of 46.9 wt% and a fineness of less than 40 μm that has biodegradable properties.

[0120] Example 3

[0121] By weight, 50 parts of the weakly alkaline hydrolyzed acrylic resin obtained in Example 1, 0.258 parts of wetting and dispersing agent BYK163, 0.258 parts of wetting and dispersing agent BYK104s, 0.258 parts of anti-settling agent BYK410, 0.215 parts of defoamer BYK052, 0.3 parts of leveling agent BYK354, 5 parts of xylene, 5 parts of N,N-dimethylformamide, and 5 parts of n-butanol were mixed evenly to obtain a preliminary mixture; the obtained preliminary mixture was... 3 parts precipitated barium sulfate, 3 parts mica powder, 4 parts brown corundum, 4 parts iron oxide red, 2 parts zinc oxide, 2.5 parts organobentonite, and 2.5 parts kaolin were mixed and dispersed at 300 rpm for 30 minutes. Then, a QM-3SP2 planetary ball mill was used to ball mill the mixture at 3000 rpm for 6 hours. After discharge, the mixture was filtered to obtain a low-friction acrylic coating with a solid content of 47.7 wt% and a fineness of less than 40 μm that has biodegradable properties.

[0122] Example 4

[0123] By weight, 40 parts of the weakly alkaline hydrolyzed acrylic resin obtained in Example 1, 0.228 parts of wetting and dispersing agent BYK163, 0.228 parts of wetting and dispersing agent BYK104s, 0.228 parts of anti-settling agent BYK410, 0.19 parts of defoamer BYK052, 0.266 parts of leveling agent BYK354, 5 parts of xylene, 5 parts of N,N-dimethylformamide, and 5 parts of n-butanol were mixed evenly to obtain a preliminary mixture; the obtained preliminary mixture... The following ingredients were mixed: 3 parts precipitated barium sulfate, 3 parts mica powder, 4 parts brown corundum, 4 parts iron oxide red, 2 parts zinc oxide, 2.5 parts organobentonite, and 2.5 parts kaolin. The mixture was stirred and dispersed at 300 rpm for 30 minutes. Then, a QM-3SP2 planetary ball mill was used to ball mill the mixture at 3000 rpm for 6 hours. After discharge, the mixture was filtered to obtain a low-friction acrylic coating with a solid content of 48.7 wt% and a fineness of less than 40 μm, which has biodegradable properties.

[0124] Application Example 1

[0125] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 2 were weighed, along with 0.195 parts of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide, and n-butanol in a mass ratio of 1:1:1 to dilute the coating. After thorough stirring, the diluted coating was sprayed onto an epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 46.9 wt%, a crosslinking degree of 60%, and a thickness of approximately 150 μm, exhibiting the characteristics of stepwise controllable hydrolysis at the interface.

[0126] Application Example 2

[0127] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 3 were weighed, and 0.181g of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide and n-butanol in a mass ratio of 1:1:1 were weighed to dilute the coating. After thorough stirring, the diluted coating was sprayed onto the epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 47.7wt%, a crosslinking degree of 60%, and a thickness of about 150μm, which has the characteristics of stepwise controllable hydrolysis at the interface.

[0128] Application Example 3

[0129] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 4 were weighed, along with 0.164 parts of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide, and n-butanol in a mass ratio of 1:1:1 to dilute the coating. After thorough stirring, the diluted coating was sprayed onto an epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 48.7 wt%, a crosslinking degree of 60%, and a thickness of approximately 150 μm, exhibiting the characteristics of stepwise controllable hydrolysis at the interface.

[0130] Application Example 4

[0131] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 4 were weighed, along with 0.137 parts of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide, and n-butanol in a mass ratio of 1:1:1 to dilute the coating. After thorough stirring, the diluted coating was sprayed onto an epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 48.7 wt%, a crosslinking degree of 50%, and a thickness of approximately 150 μm, exhibiting the characteristics of stepwise controllable hydrolysis at the interface.

[0132] Application Example 5

[0133] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 4 were weighed, and 0.109 parts of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide and n-butanol in a mass ratio of 1:1:1 were weighed to dilute the coating. After thorough stirring, the diluted coating was sprayed onto the epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 48.7 wt%, a crosslinking degree of 40%, and a thickness of about 150 μm, which has the characteristics of stepwise controllable hydrolysis at the interface.

[0134] Application Example 6

[0135] Ten parts of the low-friction acrylic coating with degradable properties obtained in Example 4 were weighed, and 0.191 parts of toluene-2,4-diisocyanate and 5 parts of a mixed solution of xylene, N,N-dimethylformamide and n-butanol in a mass ratio of 1:1:1 were weighed to dilute the coating. After thorough stirring, the diluted coating was sprayed onto the epoxy material and dried at room temperature for 24 hours to obtain a low-friction acrylic coating with a solid content of 48.7 wt%, a crosslinking degree of 70%, and a thickness of about 150 μm, exhibiting the characteristics of stepwise controllable hydrolysis at the interface.

[0136] The low-friction acrylic coatings with stepwise controllable hydrolysis characteristics obtained from test cases 1-6 were subjected to the following tests:

[0137] Adhesion testing was conducted according to GB1720-79;

[0138] The underwater oil contact angle was measured using a contact angle meter, with dichloromethane as the heavy oil.

[0139] The drag reduction rate was determined using a rheometer.

[0140] The coefficient of friction was tested using a ball-disc friction tester, with PDMS balls as the pair, a weakly alkaline solution as the lubricating medium, a frequency of 1 Hz, and an amplitude of 5 mm.

[0141] The coating was immersed in a weakly alkaline solution with a pH of approximately 8±0.5 for hydrolysis testing. The specific testing method was as follows: the coatings prepared in Application Examples 1 to 6 were immersed in a weakly alkaline solution (sodium hydroxide aqueous solution or artificial seawater) with a pH of approximately 8±0.5 for hydrolysis reaction. The coating was removed at different time intervals and the coefficient of friction of the coating was tested until the coefficient of friction of the hydrolyzed coating no longer decreased. The minimum coefficient of friction after hydrolysis and the time taken to reach the minimum coefficient of friction were recorded.

[0142] The test results are shown in Table 1.

[0143] Table 1 shows the test results of low-friction acrylic coatings with stepwise controllable hydrolysis at the interface in Application Examples 1-6.

[0144]

[0145] As shown in Table 1, the low-friction acrylic coatings with biodegradable properties provided by Application Examples 1-6 of this invention exhibit Grade 1 adhesion to the substrate, indicating high bonding strength. Furthermore, when used in an alkaline environment, the coatings prepared in Application Examples 1-6 undergo hydrolysis, resulting in a decrease in the coefficient of friction. The minimum coefficient of friction after hydrolysis is 0.06-0.12. The underwater dichloromethane contact angle is 140-149°, and the drag reduction rate is 26-35%, demonstrating good self-lubricating properties. Moreover, as shown in Application Examples 3-6, the hydrolysis rate of the coating can be controlled by adjusting the degree of crosslinking.

[0146] The coefficients of friction of the coatings obtained by drying at room temperature for 24 hours in Application Examples 1 to 6 (without immersion in a weakly alkaline solution) are as follows: 0.32 for the coating in Application Example 1, 0.25 for the coating in Application Example 2, 0.24 for the coating in Application Example 3, 0.20 for the coating in Application Example 4, 0.22 for the coating in Application Example 5, and 0.28 for the coating in Application Example 6.

[0147] Comparing the initial friction coefficients of Application Examples 1-6 before immersion in a weakly alkaline solution with the friction coefficients after stabilization in a weakly alkaline solution as shown in Table 1, it can be seen that the self-lubricating acrylic resin coating with degradable properties provided in Application Examples 1-6 of the present invention has a lower friction coefficient after immersion in a weakly alkaline solution. This indicates that when the self-lubricating acrylic resin coating with degradable properties of the present invention is used in a weakly alkaline environment, its lubricity is further improved after hydrolysis as the service time increases. In other words, the lubricity of the coating is further improved after degradation.

[0148] Comparative Example 1

[0149] Preparation of non-hydrolyzable acrylic resin: First, weigh 1.14 parts of azobisisobutyronitrile, 28.5 parts each of xylene and N,N-dimethylformamide into a beaker, and then stir thoroughly to completely dissolve the azobisisobutyronitrile. Next, weigh 6 parts of methyl methacrylate, 8 parts of butyl acrylate, 10 parts of β-hydroxyethyl methacrylate, and 14 parts of acrylic acid into a beaker and stir thoroughly to obtain a mixture solution. Then, weigh 30% of the mixture solution into a flask and react it at 90℃ with mechanical stirring for 30 min. Then, add the remaining 70% of the mixture solution into the flask at a dropping rate of 1.0 mL / min. After the addition is complete, keep the temperature for 2 h to carry out the polymerization reaction to obtain a non-hydrolyzable acrylic resin with a solid content of 40%.

[0150] By weight, 40 parts of the acrylic resin prepared in this comparative example, 0.228 parts of wetting and dispersing agent BYK163, 0.228 parts of wetting and dispersing agent BYK104s, 0.228 parts of anti-settling agent BYK410, 0.19 parts of defoamer BYK052, 0.266 parts of leveling agent BYK354, 5 parts of xylene, 5 parts of N,N-dimethylformamide, and 5 parts of n-butanol were mixed evenly to obtain a preliminary mixture; the obtained preliminary mixture... The following ingredients were mixed: 3 parts precipitated barium sulfate, 3 parts mica powder, 4 parts brown corundum, 4 parts iron oxide red, 2 parts zinc oxide, 2.5 parts organobentonite, and 2.5 parts kaolin. The mixture was stirred and dispersed at 300 rpm for 30 minutes. Then, a QM-3SP2 planetary ball mill was used to ball mill the mixture at 3000 rpm for 6 hours. After discharge, the mixture was filtered to obtain an acrylic resin coating with a solid content of 48.7 wt% and a fineness of less than 40 μm.

[0151] Weigh 10 parts by weight of the acrylic resin coating prepared in this comparative example, weigh 0.216 parts by weight of toluene-2,4-diisocyanate, and dilute the coating with an appropriate amount of a mixed solution of xylene, N,N-dimethylformamide and n-butanol in a mass ratio of 1:1:1. After thorough stirring, spray the diluted coating onto the epoxy material. Dry at room temperature for 24 hours.

[0152] The coefficient of friction of the coating obtained in Comparative Example 1 was tested according to the test method of Application Example 3, and the coefficient of friction was measured to be 0.8.

[0153] Comparing the friction coefficients of Application Examples 1-3 and Comparative Example 1, it can be seen that the self-lubricating acrylic resin coating with degradable properties provided by the present invention has a lower friction coefficient, indicating that the polymerizable organosilicon monomer in the present invention can significantly improve the lubricity of the self-lubricating acrylic resin, thereby helping to reduce the friction of the coating.

[0154] As can be seen from the above embodiments, the low-friction acrylic coating with stepwise controllable hydrolysis characteristics provided by the present invention is composed of acrylic resin that can be hydrolyzed under weakly alkaline conditions, a chemical crosslinking agent, and wear-resistant fillers. In the present invention, the acrylic resin hydrolyzed under weakly alkaline conditions ensures the stepwise degradation of the interface to form a water-lubricating layer, the chemical crosslinking structure ensures the controllable degradation of the coating, and the wear-resistant fillers ensure that the coating has good wear resistance. The acrylic coating prepared by these characteristics is determined by the acrylic silicon content and chemical crosslinking to form a degradation hydration layer at the micron scale under weakly alkaline conditions. Combined with the wear-resistant fillers, it has a low interfacial friction coefficient and stable wear resistance. This feature takes into account both the friction reduction of the top surface and the wear resistance of the bottom surface. Moreover, this micron-scale hydration layer can be continuously renewed as the interface wears, exhibiting typical low-friction self-renewal characteristics. Finally, the low-friction acrylic coating with stepwise controllable hydrolysis characteristics provided by the present invention has a certain fluid drag reduction efficiency.

[0155] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A low-friction acrylic coating having an interface stepwise controllable hydrolysis feature, characterized in that, The preparation raw materials include the following mass fractions: low-friction acrylic coating with degradable properties 10 parts and toluene-2,4-diisocyanate 0.137 parts; The low-friction acrylic coating with degradable properties includes the following mass fractions of components: acrylic resin hydrolyzed under weak alkaline conditions 40 parts, wear-resistant filler 10-15 parts, pigment filler 10-15 parts, auxiliary agent 1-2 parts, and organic solvent 15-25 parts; The acrylic resin hydrolyzed under weak alkaline conditions is obtained by polymerization of the following mass fractions of preparation raw materials: triisopropyl silyl acrylate 12 parts, methyl methacrylate 6 parts, butyl acrylate 8 parts, beta-hydroxyethyl methacrylate 10 parts, acrylic acid 14 parts, initiator 1-1.5 parts, and organic solvent 50-75 parts.

2. The low-friction acrylic coating with interface stepwise controllable hydrolysis characteristics according to claim 1, characterized in that, The initiator is azobisisobutyronitrile.

3. A low-friction acrylic coating having an interface stepwise controllable hydrolysis feature according to claim 1 or 2, characterized in that, The preparation method of the acrylic resin hydrolyzed under weak alkaline conditions includes the following steps: The triisopropyl silyl acrylate, methyl methacrylate, butyl acrylate, beta-hydroxyethyl methacrylate, acrylic acid, initiator, and organic solvent are mixed to obtain a mixed solution; the mixed solution is subjected to polymerization reaction to obtain the acrylic resin hydrolyzed under weak alkaline conditions.

4. Process for the production of low-friction acrylic coatings with interface stepwise controllable hydrolysis characteristics according to any one of claims 1 to 3, characterized in that The method includes the following steps: The low-friction acrylic coating with degradable properties, toluene-2,4-diisocyanate, and organic solvent are mixed and then coated on the surface of a substrate to obtain an initial wet film; The initial wet film is dried to obtain a low-friction acrylic coating with interface stepwise controllable hydrolysis characteristics on the surface of the substrate.

5. Use of the low-friction acrylic coating with interface stepwise controllable hydrolysis characteristics of any one of claims 1-3 or prepared by the preparation method of claim 4 as a lubricating material in an alkaline environment.

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