Ternary copolymer resin as well as preparation method and application thereof

Abstract

The invention relates to a terpolymer resin and a preparation method and application thereof, and belongs to the technical field of high polymer materials, and the terpolymer resin comprises methyl methacrylate, n-butyl acrylate and double-layer silsesquioxane bifunctional monomers. The double-layer silsesquioxane bifunctional monomer has a chemical structure as shown in a general formula (I), wherein Z represents a double-layer silsesquioxane cage type skeleton with a side group substituted by phenyl, and two ends of the skeleton respectively contain a silicon atom; o represents an oxygen atom directly connected with silicon atoms at two ends of the skeleton; l represents a connecting arm and has a structural formula shown in the specification, M represents a methylacryloyl terminal and has a structural formula shown in the specification, and R1 is selected from 1, 4-phenylene; and R2 is selected from 1, 2-ethylidene. The resin disclosed by the invention has relatively good optical transparency, surface hardness and weather-resistant stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a terpolymer resin, a preparation method and application thereof. BACKGROUND

[0002] Vinyl resins, especially copolymers based on acrylate and methacrylate, have occupied an important position in the field of architectural decoration and functional protection due to their excellent optical transparency, good weather resistance, and wide synthetic monomer sources. In the field of building energy saving, such resins are often used as matrix materials, compounded with infrared blockers or sound insulation fillers, to prepare transparent thermal insulation coatings or damping sound insulation materials, which are used for energy-saving renovation of building glass curtain walls and facades.

[0003] However, in the existing technical system, there are still some problems in the vinyl-based functional coatings applied to the outer surface of buildings. On the one hand, there is an inherent contradiction between high surface hardness and heat stress cracking resistance. In order to meet the engineering standards of scratch resistance, sand erosion resistance, and scratch resistance of building materials, the resin matrix usually needs to have a high glass transition temperature or a high crosslinking density to provide sufficient surface hardness (usually requiring a pencil hardness ≥ 2H). However, high hardness and high crosslinking density often endow the material with high brittleness, limiting the movement ability of the high molecular chain segment. When the coating is exposed to outdoor environment for a long time and subjected to thermal expansion and contraction cycles caused by diurnal temperature difference and seasonal climate change, the coating with too strong rigidity cannot effectively dissipate the accumulated thermal stress through its own deformation. This stress accumulation easily leads to the generation of microcracks on the surface of the coating, and further causes the coating to blister, peel off or lose optical transparency, seriously shortening the service life of the material.

[0004] On the other hand, the compatibility between the vinyl resin matrix and the functional inorganic fillers not only affects the appearance, but also restricts the mechanical properties of the material. In order to endow the vinyl resin with specific energy-saving functions (such as thermal insulation or enhancement), it is necessary to introduce inorganic nanoparticles or inorganic fillers. Due to the large difference in surface energy between the hydrophobic organic properties of the vinyl polymer chain segment and the hydrophilic surface of the inorganic filler, phase separation easily occurs between them. The agglomeration of inorganic fillers in the resin matrix not only significantly increases light scattering, leading to the generation of haze in transparent coatings, reducing the visible light transmittance, but also causes stress concentration as a defect point, further deteriorating the impact resistance and aging resistance of the material.

[0005] Although the prior art attempts to improve the above problems by physical blending or surface modification of fillers using traditional silane coupling agents, these methods are often difficult to achieve uniform hybridization of organic and inorganic phases at the molecular level, and are difficult to fundamentally solve the problem of the rigidity and toughness inversion of the resin matrix. Therefore, it is a technical problem to be solved to develop an ethylene-based resin with high hardness, excellent inorganic phase compatibility and the ability to adapt to thermal stress changes. SUMMARY

[0006] In view of the above, in order to overcome the defects of the prior art, the purpose of the present application is to provide a terpolymer resin and a preparation method and application thereof, so as to at least partially solve the problems raised in the background art.

[0007] The technical solutions adopted by the present application are as follows: The present application provides a terpolymer resin, the comonomer of which comprises methyl methacrylate, n-butyl acrylate and double-layer silsesquioxane bifunctional monomer, the double-layer silsesquioxane bifunctional monomer having a chemical structure as shown in the following general formula (I): (Genetic formula I) In the general formula (I), Z represents a double-layer silsesquioxane cage skeleton substituted with a phenyl group on the side group, each end of the skeleton containing one silicon atom; O represents an oxygen atom directly connected to the silicon atom at each end of the skeleton; L represents a connecting arm, the structure of which is as follows:

[0008] M represents a methacryl end, the structure of which is as follows:

[0009] wherein R1 is selected from 1,4-phenylene; R2 is selected from 1,2-ethylene; the carbonyl carbon atom at the left end of the connecting arm L is connected to the oxygen atom at the end group of the skeleton in the general formula (I); and the oxygen atom at the right end of the connecting arm L is connected to the carbonyl carbon atom in the group M.

[0010] In some embodiments of the present application, the molar ratio of methyl methacrylate, n-butyl acrylate and double-layer silsesquioxane bifunctional monomer in the terpolymer resin is (55-65):(30-40):(3-8).

[0011] In some embodiments of the present application, the terpolymer resin has solubility, which is soluble in toluene or butyl acetate at 25°C.

[0012] The present application provides a preparation method of a terpolymer resin, comprising the following steps: S1, preparing a double-layer silsesquioxane bifunctional monomer; S2, methyl methacrylate, n-butyl acrylate and double-layer silsesquioxane bifunctional monomer are dissolved in an organic solvent, an initiator and a chain transfer agent are added to obtain a reaction mixture; S3, the reaction mixture is subjected to oxygen removal treatment and heated to 70-80 DEG C under a protective atmosphere for polymerization; S4, the monomer conversion rate is monitored, and the reaction is terminated when the conversion rate reaches a predetermined range, and the ternary copolymer resin is obtained by precipitation and purification.

[0013] In some embodiments of the present application, in step S2, the organic solvent is toluene; the initiator is azobisisobutyronitrile; the chain transfer agent is 2-cyano-2-propyl dodecyl trithiocarbonate; the total mole of methyl methacrylate, n-butyl acrylate and double-layer silsesquioxane bifunctional monomer, and the mole ratio of the chain transfer agent and the initiator is 200:1:(0.1-0.3); in step S4, the predetermined range is that the monomer conversion rate reaches 60-70%.

[0014] In some embodiments of the present application, the preparation of the double-layer silsesquioxane bifunctional monomer in step S1 comprises the following steps: S101, phenyltrimethoxysilane and sodium hydroxide are dissolved in isopropyl alcohol, and hydrolysis condensation reaction is carried out under heating reflux conditions to generate double-layer silsesquioxane tetrasodium salt precipitate; the precipitate is collected and suspended in tetrahydrofuran, dichloromethylsilane is added under ice bath conditions for end-capping reaction, then water is added for in-situ hydrolysis, and double-layer silsesquioxane diol is obtained by separation and purification; S102, 4,4'-dithiodibenzoic acid is dissolved in N,N-dimethylformamide, 2-hydroxyethyl methacrylate is added, and dicyclohexyl carbodiimide and 4-dimethylamino pyridine are added, and the reaction is stirred at room temperature, and after the reaction is completed, filtration, separation and purification are carried out to obtain a disulfide monoester intermediate; S103, the double-layer silsesquioxane diol and the disulfide monoester intermediate are dissolved in anhydrous dichloromethane, dicyclohexyl carbodiimide and 4-dimethylamino pyridine are added, and the reaction is stirred at room temperature, and after the reaction is completed, filtration, separation and purification are carried out to obtain the double-layer silsesquioxane bifunctional monomer.

[0015] In some embodiments of the present application, in step S101, the molar ratio of the phenyltrimethoxysilane, sodium hydroxide and water is 1:(0.35-0.45):(0.35-0.45); the hydrolysis and condensation reaction is carried out at a reflux temperature of 80-85℃, and the reaction time is 3-5 hours; in the capping reaction, the amount of dichloromethylsilane added is in excess relative to the phenyltrimethoxysilane, the reaction temperature is controlled at 0-5℃ under ice bath conditions, and the reaction time is 3-5 hours; and the stirring time for in-situ hydrolysis is 0.5-1.5 hours.

[0016] In some embodiments of the present application, in step S102, the molar ratio of the 4,4'-dithiodibenzoic acid and 2-hydroxyethyl methacrylate is 1:(0.95-1.05); the molar ratio of the 4,4'-dithiodibenzoic acid, dicyclohexyl carbodiimide and 4-dimethylamino pyridine is 1:(1.0-1.2):(0.05-0.15); and the reaction time is 20-28 hours.

[0017] In some embodiments of the present application, in step S103, the molar ratio of the double-layer silsesquioxane diol and the disulfide monoester intermediate is 1:(2.05-2.20); the molar ratio of the double-layer silsesquioxane diol, dicyclohexyl carbodiimide and 4-dimethylamino pyridine is 1:(2.2-2.5):(0.2-0.4); and the reaction time is 40-50 hours.

[0018] The third aspect of the present application provides a coating composition comprising the above-mentioned terpolymer resin, an organic solvent selected from butyl acetate, toluene or a mixture thereof, and optionally a leveling agent, a defoaming agent or a functional filler.

[0019] The present application has the following beneficial effects: The present application adopts a preparation scheme combining double-layer silsesquioxane main chain type structure design, dynamic covalent chemistry and in-situ terpolymerization, which has the advantages of realizing molecular-level homogenization of organic-inorganic components by covalent bonding technology, effectively solving the cracking problem of high-hardness coatings in complex thermal environments by the stress relaxation mechanism of disulfide bonds, and overcoming the contradiction between hardness and toughness through the synergistic effect between monomers, thereby improving the optical transparency, surface hardness and weathering stability of the coating, and meeting the application requirements of high-performance building functional coatings. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] To address the problems raised in the background art, the first aspect of this invention provides a ternary copolymer resin, wherein the comonomers of the ternary copolymer resin include: methyl methacrylate, n-butyl acrylate, and a bilayer silsesquioxane bifunctional monomer, wherein the bilayer silsesquioxane bifunctional monomer has the chemical structure shown in the following general formula (I): (General Formula I) In general formula (I), Z represents a bilayer silsesquioxane cage-like framework with phenyl-substituted side groups, each end of which contains a silicon atom; O represents an oxygen atom directly bonded to the silicon atoms at both ends of the framework; L represents a connecting arm, and its structural formula is:

[0024] M represents the methacryloyl terminus, and its structural formula is:

[0025] Wherein, R1 is selected from 1,4-phenylene; R2 is selected from 1,2-ethylene; the carbonyl carbon atom at the left end of the connecting arm L is connected to the oxygen atom of the skeletal end group in general formula (I); the oxygen atom at the right end of the connecting arm L is connected to the carbonyl carbon atom in group M.

[0026] First, this invention constructs a bilayer silsesquioxane (DDSQ) functional monomer with an "inorganic core-organic double arm" structure and introduces it into the polymer backbone through in-situ copolymerization. The DDSQ cage-like framework provides mechanical support as a rigid inorganic core, while the methacryloyl groups at both ends act as reactive "double arms," ​​enabling covalent bonding with monomers such as methyl methacrylate. This design overcomes the physical agglomeration and phase separation problems caused by the difference in surface energy between inorganic fillers and organic resins in traditional technologies, achieving molecular-level uniform dispersion of inorganic components in the resin matrix. Simultaneously, the nanoscale effect of the DDSQ cage avoids scattering of visible light. This relatively uniform microstructure can improve the surface hardness and modulus of the coating while effectively avoiding optical haze caused by filler agglomeration, thus ensuring high light transmittance of the coating.

[0027] Secondly, this invention introduces aromatic disulfide bonds as dynamic response units into the polymer crosslinking network. These chemical bonds are located on the connecting arms between the rigid DDSQ cage and the flexible polymer segments, endowing the cured crosslinking network with specific "dynamic adaptability." When the coating experiences thermal expansion and contraction stress due to diurnal temperature variations in outdoor environments, or suffers microscopic damage from external pressure, the aromatic disulfide bonds can undergo reversible bond exchange reactions under thermal excitation. This microscopic bond breaking and recombination mechanism allows polymer segments to undergo topological rearrangement to dissipate internally accumulated stress, fundamentally solving the problem of thermal stress cracking caused by excessive rigidity in high-hardness vinyl coatings, and endowing the material with intrinsic repair capabilities for microcracks, thus extending the coating's service life.

[0028] Furthermore, this invention achieves simultaneous optimization of material weather resistance and adhesion through the synergistic effect of the components in the ternary copolymer system. Utilizing the high-bond-energy silicon-oxygen (Si-O) bond structure in the DDSQ backbone, the polymer backbone's resistance to ultraviolet radiation and oxidation is enhanced; simultaneously, the flexible segments provided by n-butyl acrylate effectively regulate the resin's glass transition temperature and polarity. This molecular design, combining rigidity and flexibility, not only enhances the coating's solvent resistance through chemical cross-linking but also ensures good wetting and adhesion of the coating to substrates such as glass and metal using polar side groups, solving the problem of traditional high-hardness coatings easily peeling off due to their brittleness.

[0029] In summary, this invention employs a preparation scheme combining a bilayer silsesquioxane backbone structure design, dynamic covalent chemistry, and ternary in-situ copolymerization. The advantage of this scheme lies in the molecular-level homogenization of organic-inorganic components achieved through covalent bonding technology. Combined with the stress relaxation mechanism of disulfide bonds, it effectively solves the cracking problem of high-hardness coatings under complex thermal environments. Furthermore, it overcomes the contradiction between hardness and toughness through the synergistic effect between monomers, thereby improving the optical transparency, surface hardness, and weather resistance of the coating and meeting the application requirements of high-performance architectural functional coatings.

[0030] In some embodiments, the molar ratio of methyl methacrylate, n-butyl acrylate, and bilayer silsesquioxane bifunctional monomers in the ternary copolymer resin is (55-65):(30-40):(3-8). Specifically, 55-65% methyl methacrylate forms the rigid backbone of the polymer, ensuring excellent optical transparency and basic hardness of the coating; 30-40% n-butyl acrylate, as an internal plasticizer, effectively alleviates the brittleness of the rigid backbone by introducing flexible side chains, giving the coating good impact resistance and adhesion to the substrate; and 3-8% bilayer silsesquioxane bifunctional monomers provide a suitable crosslinking density. This content is sufficient to construct a dynamic inorganic reinforcing network with stress relaxation capabilities, while effectively avoiding gelation during polymerization or excessive embrittlement of the coating due to excessive polyfunctional monomers. This ensures that the resin possesses high hardness while also exhibiting good processing rheology and self-healing efficiency.

[0031] In some embodiments, the ternary copolymer resin is soluble in toluene or butyl acetate at 25°C. This solubility indicates that, despite the introduction of a multifunctional bilayer silsesquioxane crosslinking agent into the polymerization system, irreversible macroscopic gelation of the resin during the synthesis stage can be successfully avoided through effective control of the polymerization process, maintaining it in a soluble branched structure or prepolymer state. This excellent solubility allows the resin to be fully miscible with commonly used industrial solvents and additives such as toluene and butyl acetate, preparing a homogeneous liquid coating system. Simultaneously, the polymeric segments in the dissolved state can fully expand during coating, resulting in good wetting and leveling of the coating liquid on the surface of the building substrate, solving the process problem that traditional high-hardness crosslinked materials often cannot be directly coated due to their poor solubility.

[0032] A second aspect of this invention provides a method for preparing a ternary copolymer resin, comprising the following steps: S1. Preparation of bilayer silsesquioxane bifunctional monomers; S2. Methyl methacrylate, n-butyl acrylate and bilayer silsesquioxane bifunctional monomers are dissolved in an organic solvent, and an initiator and chain transfer agent are added to obtain a reaction mixture. S3. The reaction mixture is deoxygenated and heated to 70°C to 80°C under a protective atmosphere to carry out a polymerization reaction; S4. Monitor the monomer conversion rate. When the conversion rate reaches the predetermined range, terminate the reaction and precipitate and purify to obtain the ternary copolymer resin.

[0033] This process utilizes chain transfer agents to regulate the activity of the growing chains, combined with deoxygenation and isothermal control, to ensure the stability of reaction kinetics and the uniformity of monomer sequences. More importantly, by terminating the reaction within a specific conversion range, the polymer structure is effectively locked in the highly branched prepolymerization stage before the gel point. This method not only avoids the resin insolubility problem caused by excessive crosslinking, ensuring the solubility and processability of the material in subsequent coating applications, but also achieves a narrower molecular weight distribution and consistent batch quality.

[0034] Preferably, in step S2, the organic solvent is toluene; the initiator is azobisisobutyronitrile; the chain transfer agent is 2-cyano-2-propyldodecyl trithiocarbonate; the total molar amount of the monomers methyl methacrylate, n-butyl acrylate, and bilayer silsesquioxane bifunctional monomers, in a molar ratio of the chain transfer agent and the initiator, is 200:1:(0.1-0.3); in step S4, the predetermined range is a monomer conversion rate between 60% and 70%. By introducing a trithiocarbonate chain transfer agent and limiting the specific molar ratio of monomer, chain transfer agent, and initiator (200:1:0.1-0.3), the bimolecular termination side reaction in free radical polymerization is effectively suppressed. This not only controls the polymer chain length within a predetermined range and significantly reduces the polydispersity of the molecular weight distribution, but more importantly, it effectively delays the appearance of the gel point in a system containing a bifunctional crosslinking agent, thereby successfully preparing a terpolymer with a uniform structure, no macroscopic gelation, and easy processing.

[0035] In addition, during the polymerization process, samples were taken from the reaction system every hour, and the decay of the integral area of ​​the characteristic peak of the monomer double bond protons (e.g., the region of δ=5.5-6.5ppm) in the reaction solution was monitored using 1H NMR spectroscopy to calculate the monomer conversion rate. The reaction was terminated when the conversion rate reached the 60%-70% range.

[0036] In some embodiments, the preparation of the bilayer silsesquioxane bifunctional monomer in step S1 includes the following steps: S101. Phenyltrimethoxysilane and sodium hydroxide are dissolved in isopropanol and subjected to hydrolysis condensation reaction under reflux to generate a tetrasodium bilayer silsesquioxane precipitate. The precipitate is collected and suspended in tetrahydrofuran. Dichloromethylsilane is added under ice bath conditions to carry out end-capping reaction. Water is then added for in-situ hydrolysis. After separation and purification, bilayer silsesquioxane diol is obtained. S102. Dissolve 4,4'-dithiodibenzoic acid in N,N-dimethylformamide, add 2-hydroxyethyl methacrylate, and add dicyclohexylcarbodiimide and 4-dimethylaminopyridine. Stir the reaction at room temperature. After the reaction is completed, filter, separate and purify to obtain the disulfide monoester intermediate. S103. Dissolve the bilayer silsesquioxane diol and the disulfide monoester intermediate in anhydrous dichloromethane, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine, stir and react at room temperature, and after the reaction is completed, filter, separate and purify to obtain the bilayer silsesquioxane bifunctional monomer.

[0037] Preferably, in step S101, the molar ratio of phenyltrimethoxysilane, sodium hydroxide, and water is 1:(0.35-0.45):(0.35-0.45); the hydrolysis-condensation reaction is carried out at a reflux temperature of 80°C to 85°C for 3 to 5 hours; in the end-capping reaction, the amount of dichloromethylsilane added is in excess relative to phenyltrimethoxysilane, the reaction temperature is controlled under ice bath conditions of 0°C to 5°C, and the reaction time is 3 to 5 hours; the stirring time for the in-situ hydrolysis is 0.5 to 1.5 hours.

[0038] Preferably, in step S102, the molar ratio of 4,4'-dithiobenzoic acid to 2-hydroxyethyl methacrylate is 1:(0.95-1.05); the molar ratio of 4,4'-dithiobenzoic acid, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(1.0-1.2):(0.05-0.15); and the reaction time is 20 to 28 hours.

[0039] Preferably, in step S103, the molar ratio of the bilayer silsesquioxane diol to the disulfide monoester intermediate is 1:(2.05-2.20); the molar ratio of the bilayer silsesquioxane diol, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(2.2-2.5):(0.2-0.4); and the reaction time is 40 to 50 hours.

[0040] Specifically, step S101, by limiting the feed ratio and reflux temperature, regulates the rate and direction of silane hydrolysis and condensation, promoting the preferential formation of thermodynamically stable bilayer cage structures and suppressing the formation of random or ladder-shaped byproducts. Step S102, through stoichiometric control, effectively reduces the probability of diesterization side reactions and significantly improves the selectivity of monofunctional intermediates. Step S103, by overfeeding and extending the reaction time, overcomes the shielding effect of the sterically hindered cage structure of DDSQ on reaction sites, ensuring complete conversion of terminal hydroxyl groups. Optimization of process parameters ensures the clarity and purity of the chemical structure of the bifunctional monomer, laying the foundation for the subsequent preparation of high-performance polymers.

[0041] A third aspect of this invention provides a coating composition comprising the aforementioned ternary copolymer resin, an organic solvent selected from butyl acetate, toluene, or mixtures thereof, and optionally a leveling agent, defoamer, or functional filler. The ternary copolymer resin, as the core film-forming substance, imparts basic mechanical strength and functional properties to the coating. The selected butyl acetate or toluene solvent system, based on solubility parameters matching the resin, combined with optional leveling agents, defoamers, or functional fillers, can produce a coating with excellent performance.

[0042] The present invention will be further described below by way of specific embodiments.

[0043] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods already existing in the art; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0044] Example 1: (1) Phenylacetyltrimethoxysilane, sodium hydroxide, and deionized water were added to a reaction vessel in a molar ratio of 1:0.35:0.35, and isopropanol was added to dissolve them. The mixture was heated to 80°C under stirring and kept under reflux for 3 hours to produce tetrasodium bilayer silsesquioxane. The tetrasodium bilayer silsesquioxane was collected by filtration, washed with isopropanol, and then suspended in tetrahydrofuran. The suspension was cooled to 0°C in an ice-water bath, and dichloromethylsilane (in excess relative to phenyltrimethoxysilane) was added dropwise for end-capping reaction for 3 hours. Deionized water was then added to the system, and in-situ hydrolysis was carried out by stirring at room temperature for 0.5 hours. After the reaction was completed, the mixture was allowed to stand and separated. The organic phase was dried, filtered, and the solvent was removed by rotary evaporation to obtain bilayer silsesquioxane diol.

[0045] (2) 4,4'-dithiobenzoic acid and 2-hydroxyethyl methacrylate were dissolved in N,N-dimethylformamide at a molar ratio of 1:0.95. Dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) were added to the solution, wherein the molar ratio of 4,4'-dithiobenzoic acid, DCC, and DMAP was 1:1.0:0.05. The reaction was stirred at room temperature (25°C) for 20 hours. After the reaction was completed, the insoluble matter was removed by filtration, and the filtrate was purified to obtain the disulfide monoester intermediate.

[0046] (3) The bilayer silsesquioxane diol obtained in step (1) and the disulfide monoester intermediate obtained in step (2) are dissolved in anhydrous dichloromethane at a molar ratio of 1:2.05. DCC and DMAP are added, wherein the molar ratio of bilayer silsesquioxane diol, DCC and DMAP is 1:2.2:0.2. The reaction is carried out under sealed stirring at room temperature for 40 hours. After the reaction is completed, the byproducts are removed by filtration, and the filtrate is washed with water, dried, concentrated and recrystallized to obtain the target product, the bilayer silsesquioxane bifunctional monomer (hereinafter referred to as the functional monomer).

[0047] (4) Methyl methacrylate (MMA), n-butyl acrylate (n-BA), and the functional monomers prepared above were added to a reactor equipped with a stirrer, a condenser, and a nitrogen gas inlet. Toluene was added as a solvent to dissolve them. The molar ratio of the three monomers was MMA:n-BA:functional monomer = 60:35:5. Azobisisobutyronitrile (AIB) and 2-cyano-2-propyldodecyl trithiocarbonate (2-Cyano-2-propyldodecyl trithiocarbonate) were added to the monomer solution. The molar ratio of the total monomers to the chain transfer agent and the initiator was 200:1:0.2. High-purity nitrogen was introduced into the reaction system for 30 minutes to remove dissolved oxygen. Under a nitrogen protective atmosphere, the oil bath temperature was raised to 75°C, and stirring was started to carry out the polymerization reaction. Samples were taken every hour during the reaction, and the monomer conversion rate was monitored by 1H NMR spectroscopy. When the monomer conversion rate reached 65%, heating was stopped immediately and air was introduced to terminate the reaction. The reaction solution was slowly poured into excess methanol to precipitate the solid, which was then filtered and dried under vacuum to obtain the ternary copolymer resin.

[0048] Example 2: The only difference from Example 1 is: In step (1), the molar ratio of phenyltrimethoxysilane, sodium hydroxide and water is adjusted to 1:0.45:0.45; the reflux temperature is adjusted to 85℃ and the reaction time is 5 hours; the end-capping reaction temperature is 5℃ and the end-capping time is 5 hours; the in-situ hydrolysis time is 1.5 hours.

[0049] In step (2), the molar ratio of 4,4'-dithiobenzoic acid to 2-hydroxyethyl methacrylate is adjusted to 1:1.05; the molar ratio of 4,4'-dithiobenzoic acid, DCC and DMAP is adjusted to 1:1.2:0.15; and the reaction time is 28 hours.

[0050] In step (3), the molar ratio of bilayer silsesquioxane diol to disulfide monoester intermediate is adjusted to 1:2.20; the molar ratio of bilayer silsesquioxane diol, DCC and DMAP is adjusted to 1:2.5:0.4; and the reaction time is 50 hours.

[0051] In step (4), MMA:n-BA:functional monomer = 65:32:3.

[0052] Example 3: The only difference from Example 1 is that in step (4), MMA:n-BA:functional monomer = 55:40:5.

[0053] Example 4: The only difference from Example 1 is that in step (4), MMA:n-BA:functional monomer = 56:36:8.

[0054] Example 5: The only difference from Example 1 is that in step (4), MMA:n-BA:functional monomer = 63:30:7. The molar ratio of total monomer molarity to chain transfer agent and initiator is adjusted to 200:1:0.1. The polymerization reaction temperature is set to 70°C. The reaction is terminated when the monomer conversion rate reaches 60%.

[0055] Example 6: The only difference from Example 1 is that in step (4), the molar ratio of the total monomer molar amount to the chain transfer agent and initiator is adjusted to 200:1:0.3. The polymerization reaction temperature is set to 80°C. The reaction is terminated when the monomer conversion rate reaches 70%.

[0056] Comparative Example 1: The difference from Example 1 is that no bilayer silsesquioxane bifunctional monomer is added. Methyl methacrylate and n-butyl acrylate are dissolved in toluene at a molar ratio of 63:37. The amounts of initiator and chain transfer agent, as well as the polymerization process conditions, are the same as in Example 1.

[0057] Comparative Example 2: The difference from Example 1 is that in step (2) of preparing the bilayer silsesquioxane bifunctional monomer, terephthalic acid was used in equimolar substitution for 4,4'-dithiodibenzoic acid, thereby obtaining a comparative monomer with a rigid linker structure and no disulfide bonds. This comparative monomer was then used to replace the functional monomer in Example 1 for polymerization, with the feed ratio and process being consistent with Example 1.

[0058] The resins prepared in Examples 1 to 6 and Comparative Examples 1 to 2 were dissolved in a mixed solvent of butyl acetate and toluene (volume ratio 1:1) to prepare coating compositions with a solid content of 40%. The coatings were applied to glass plates using a wire bar coater, dried at room temperature, and then completely cured in a 60°C oven. The dry film thickness was controlled at 30±5 μm, and the following performance tests were performed.

[0059] Test method: Appearance and Transparency: Visually inspect the coating surface under natural diffused light to check for smoothness, haze, or particles. According to GB / T2410-2008 "Determination of Light Transmittance and Haze of Transparent Plastics", the light transmittance of the coating on the glass substrate was tested at a wavelength of 550 nm using a UV-Vis spectrophotometer.

[0060] Pencil hardness: According to GB / T6739-2006 "Determination of Hardness of Paints and Varnishes by Pencil Method", a trolley-type pencil hardness tester was used under a 750g load, and a Zhonghua brand high-grade drawing pencil was used for testing. The hardest pencil grade that did not scratch the paint film was recorded.

[0061] Adhesion: Tested according to GB / T9286-1998 "Cross-cut test for paint and varnish films" using a cross-cut tester (1mm spacing). Grade 0 indicates that the cut edge is completely smooth with no peeling; Grade 1 indicates that there is a small amount of coating peeling at the intersection, affecting an area of ​​no more than 5%.

[0062] Thermal shock resistance: Tested using a high and low temperature alternating test chamber. The cured coating sample was placed in an 80℃ environment and kept at that temperature for 1 hour. It was then removed and transferred to a -20℃ environment within 1 minute and kept at that temperature for 1 hour. This process was recorded as one cycle. After 20 consecutive cycles, the coating surface was observed using a 10x magnifying glass for microcracks, blistering, or peeling.

[0063] The data from the above tests were analyzed, and the results are shown in Table 1.

[0064] Table 1

[0065] Analysis of the results in Table 1 shows that, by comparing Examples 1-6 with Comparative Example 1, the introduction of a bilayer silsesquioxane bifunctional monomer significantly increased the pencil hardness of the resin coating from HB to 3H-4H, while maintaining a light transmittance above 91% without significant decrease. This indicates that the copolymerization strategy of this invention successfully and uniformly introduced the inorganic cage structure into the organic network, greatly enhancing surface hardness while avoiding optical haze caused by macroscopic phase separation. After undergoing 20 rigorous thermal shock cycles, the coating surfaces of Examples 1-6 remained intact without crack formation. In contrast, although Comparative Example 2 also contained a bilayer silsesquioxane structure and had a hardness as high as 3H, the rigid chemical bonds (without disulfide bonds) of the connecting arms prevented effective dissipation of internal stress caused by temperature changes, resulting in significant cracks during the thermal shock test.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A ternary copolymer resin, characterized in that, The comonomers of the ternary copolymer resin include: methyl methacrylate, n-butyl acrylate, and a bilayer silsesquioxane bifunctional monomer, wherein the bilayer silsesquioxane bifunctional monomer has the chemical structure shown in the following general formula (I): (General Formula I) In general formula (I), Z represents a bilayer silsesquioxane cage-like framework with phenyl-substituted side groups, each end of which contains a silicon atom; O represents an oxygen atom directly bonded to the silicon atoms at both ends of the framework; L represents a connecting arm, and its structural formula is: M represents the methacryloyl terminus, and its structural formula is: Wherein, R1 is selected from 1,4-phenylene; R2 is selected from 1,2-ethylene; the carbonyl carbon atom at the left end of the connecting arm L is connected to the oxygen atom of the skeletal end group in general formula (I); the oxygen atom at the right end of the connecting arm L is connected to the carbonyl carbon atom in group M.

2. The ternary copolymer resin according to claim 1, characterized in that, In the ternary copolymer resin, the molar ratio of methyl methacrylate, n-butyl acrylate and bilayer silsesquioxane bifunctional monomer is (55-65):(30-40):(3-8).

3. The ternary copolymer resin according to claim 1, wherein the ternary copolymer resin is soluble and is soluble in toluene or butyl acetate at 25°C.

4. A method for preparing the ternary copolymer resin according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Preparation of bilayer silsesquioxane bifunctional monomers; S2. Methyl methacrylate, n-butyl acrylate and bilayer silsesquioxane bifunctional monomers are dissolved in an organic solvent, and an initiator and chain transfer agent are added to obtain a reaction mixture. S3. The reaction mixture is deoxygenated and heated to 70°C to 80°C under a protective atmosphere to carry out a polymerization reaction; S4. Monitor the monomer conversion rate. When the conversion rate reaches the predetermined range, terminate the reaction and precipitate and purify to obtain the ternary copolymer resin.

5. The preparation method according to claim 4, characterized in that, In step S2, the organic solvent is toluene; the initiator is azobisisobutyronitrile; the chain transfer agent is 2-cyano-2-propyldodecyl trithiocarbonate; the total molar amount of the monomers methyl methacrylate, n-butyl acrylate, and bilayer silsesquioxane bifunctional monomers, in a molar ratio of the chain transfer agent and the initiator, is 200:1:(0.1-0.3); in step S4, the predetermined range is a monomer conversion rate between 60% and 70%.

6. The preparation method according to claim 4, characterized in that, The preparation of the bilayer silsesquioxane bifunctional monomer in step S1 includes the following steps: S101. Phenyltrimethoxysilane and sodium hydroxide are dissolved in isopropanol and subjected to hydrolysis condensation reaction under reflux to generate a tetrasodium bilayer silsesquioxane precipitate. The precipitate is collected and suspended in tetrahydrofuran. Dichloromethylsilane is added under ice bath conditions to carry out end-capping reaction. Water is then added for in-situ hydrolysis. After separation and purification, bilayer silsesquioxane diol is obtained. S102. Dissolve 4,4'-dithiodibenzoic acid in N,N-dimethylformamide, add 2-hydroxyethyl methacrylate, and add dicyclohexylcarbodiimide and 4-dimethylaminopyridine. Stir the reaction at room temperature. After the reaction is completed, filter, separate and purify to obtain the disulfide monoester intermediate. S103. Dissolve the bilayer silsesquioxane diol and the disulfide monoester intermediate in anhydrous dichloromethane, add dicyclohexylcarbodiimide and 4-dimethylaminopyridine, stir and react at room temperature, and after the reaction is completed, filter, separate and purify to obtain the bilayer silsesquioxane bifunctional monomer.

7. The preparation method according to claim 6, characterized in that, In step S101, the molar ratio of phenyltrimethoxysilane, sodium hydroxide, and water is 1:(0.35-0.45):(0.35-0.45); the hydrolysis-condensation reaction is carried out at a reflux temperature of 80°C to 85°C for 3 to 5 hours; in the end-capping reaction, the amount of dichloromethylsilane added is in excess relative to phenyltrimethoxysilane, the reaction temperature is controlled under ice bath conditions of 0°C to 5°C, and the reaction time is 3 to 5 hours; the stirring time for the in-situ hydrolysis is 0.5 to 1.5 hours.

8. The preparation method according to claim 6, characterized in that, In step S102, the molar ratio of 4,4'-dithiobenzoic acid to 2-hydroxyethyl methacrylate is 1:(0.95-1.05); the molar ratio of 4,4'-dithiobenzoic acid, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(1.0-1.2):(0.05-0.15); and the reaction time is 20 to 28 hours.

9. The preparation method according to claim 6, characterized in that, In step S103, the molar ratio of the bilayer silsesquioxane diol to the disulfide monoester intermediate is 1:(2.05-2.20); the molar ratio of the bilayer silsesquioxane diol, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1:(2.2-2.5):(0.2-0.4); and the reaction time is 40 to 50 hours.

10. A coating composition, characterized in that, It comprises the ternary copolymer resin according to any one of claims 1 to 3, an organic solvent selected from butyl acetate, toluene or mixtures thereof, and optionally a leveling agent, defoamer or functional filler.

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