A cashew nut phenol-based waterborne transparent material and its preparation method

Abstract

This invention provides a cashew nut shell-based waterborne transparent material, comprising, by weight, a dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer, cashew nut shell polyoxyethylene ether acrylate, a polyhedral oligomeric silsesquioxane, a waterborne photoinitiator, and water. This invention also provides a method for preparing the aforementioned cashew nut shell-based waterborne transparent material, comprising the following steps: adding methacryloyloxypropyl cage-like polysesquioxane to cashew nut shell polyoxyethylene ether acrylate until completely dissolved to obtain a homogeneous oil-phase premix; mixing the waterborne polyurethane acrylate prepolymer emulsion with water to obtain an waterborne matrix mixture; slowly adding the homogeneous oil-phase premix to the waterborne matrix mixture and emulsifying by high-speed shearing to obtain a composite emulsion; and adding the waterborne photoinitiator to the composite emulsion under light-protected conditions, stirring, and filtering to obtain the final product.

Description

Technical Field

[0001] This invention relates to the field of display panel glass coatings, specifically to a cashew phenol-based water-based transparent coating, its preparation method, and its application. Background Technology

[0002] In recent years, with the popularization of smart terminals, in-vehicle displays and public touch devices, the demand for anti-fingerprint (AF) coatings on display glass surfaces has been increasing.

[0003] Traditional fingerprint-resistant (AF) coatings commonly employ perfluoroalkyl compounds (PFAS) or fluorinated acrylates, leveraging their extremely low surface energy to achieve excellent hydrophobic and oleophobic properties. However, fluorinated compounds exhibit environmental persistence, bioaccumulation, and potential toxicity, and their production and use are strictly restricted by the EU REACH regulation and my country's Stockholm Convention on Persistent Organic Pollutants. Therefore, developing fluorine-free anti-fingerprint coatings has become an important development direction in the field of display protective materials.

[0004] UV-cured coatings are a technological solution to replace perfluoroalkyl compounds (PFAS) or fluorinated acrylates. UV curing technology has been widely used in the preparation of transparent coatings due to its advantages such as fast curing speed, low energy consumption, and high production efficiency. However, existing fluorine-free anti-fingerprint UV-cured coatings still have significant shortcomings in terms of environmental friendliness, durability, mechanical properties, and functionality.

[0005] Chinese patent application CN202410154920.2 discloses a vegetable oil-modified fluorine-free anti-fingerprint transparent coating material, which uses a silicone-modified polyurethane acrylate prepolymer physically blended with vegetable oils (tung oil, linseed oil, etc.), and adds hydrophobic nanoparticles and a large amount of organic solvents, and then cures it into a film by UV curing. Although this technology achieves fluorine-free coating, it still has the following defects: First, this system is a typical solvent-based coating, with the amount of organic solvent reaching 2-8 times the total mass of resin and vegetable oil. A large amount of solvent needs to evaporate before curing, resulting in significant VOC emissions, which contradicts the current environmental regulations guiding the coating industry towards "oil-to-water" conversion. Second, the vegetable oil is introduced through physical blending, which has limited compatibility with the silicone prepolymer. After long-term storage or exposure to sweat and sebum, it is prone to migration and seepage, leading to a decrease in hydrophobic properties. Third, to obtain sufficient hydrophobicity, an additional 10-20% of hydrophobic nanoparticles (such as nano-silica) need to be added. The nanoparticles are prone to agglomeration and introduction into the light scattering interface, resulting in increased coating haze and decreased light transmittance.

[0006] Chinese patent application CN202411588866.9 discloses a tung oil derivative composite fluorine-free anti-fingerprint transparent coating material, which is prepared by a two-step high-temperature reaction of tung oil anhydride with hydroxy acrylate and glycidyl methacrylate (reaction at 100-120℃ for 3-5 hours, reaction at 90-110℃ for 3-4 hours) to prepare tung oil-based photoactive monomers, and then compounded with polydimethylsiloxane modified polyurethane acrylate prepolymer for UV curing. Although this technology chemically modifies tung oil into reactive monomers, it still has many limitations: First, it remains a solvent-based system, with the amount of organic solvent used being 1-4 times the total mass of the prepolymer and monomer, failing to fundamentally solve the VOC emission problem; second, tung oil molecules contain conjugated triene structures, which are highly susceptible to photo-oxidation, cross-linking, or chain scission under UV curing and long-term light exposure, generating chromophores such as conjugated carbonyl groups, leading to severe yellowing of the coating and affecting transparency (the transmittance of its examples has dropped to 85-87%, significantly lower than the 92% of the pure organosilicon system); third, the preparation process of this tung oil-based photoactive monomer is lengthy, energy-intensive, and has poor atom economy, which is not conducive to industrial scale-up; in addition, this coating system is highly dependent on PDMS segments to provide low surface energy, and the cohesive energy density of polydimethylsiloxane is extremely low (approximately 12.5 cal / cm). 3 This is significantly lower than that of conventional acrylic resins (approximately 80-100 cal / cm³). 3 Furthermore, the C18 flexible long chain in the tung oil-based monomer further reduces the rigidity of the crosslinking network, significantly reducing the overall crosslinking density and rigidity of the coating, thereby restricting the improvement of the coating's hardness and wear resistance.

[0007] Therefore, there is an urgent need in this field for a new type of coating material that combines water-based environmental protection, rapid UV curing, high transparency, high hardness and wear resistance, and fingerprint resistance. Summary of the Invention

[0008] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a water-based transparent material based on cashew nut shell phenol. The water-based UV-curable fluorine-free anti-fingerprint transparent material based on cashew nut shell phenol provided by this invention achieves multifunctional integration of coating properties such as superhydrophobicity, high transparency, anti-fingerprint properties, high hardness, and wear resistance by constructing a ternary synergistic system of cashew nut shell phenol polyoxyethylene ether acrylate active monomer, dimer acid-based water-based organosilicon-modified polyurethane acrylate, and cage-like polyhedral oligomeric silsesquioxane.

[0009] Another object of the present invention is to provide a method for preparing the aforementioned waterborne transparent material based on cashew nut shell phenol. This method is based on LED-UV curing and can achieve efficient preparation of waterborne transparent materials based on cashew nut shell phenol.

[0010] A third objective of this invention is to provide an aqueous transparent coating prepared from the aforementioned cashew phenol-based aqueous transparent material.

[0011] A fourth objective of this invention is to provide a method for preparing the aforementioned water-based transparent coating.

[0012] This invention is achieved through the following technical solution: A cashew nut phenol-based waterborne transparent material, by weight, comprises 30-60 parts of dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer, 10-30 parts of cashew nut phenol polyoxyethylene ether acrylate, 2-8 parts of polyhedral oligomeric silsesquioxane, 1-5 parts of waterborne photoinitiator, and 15-35 parts of water. The structure of the cashew phenol polyoxyethylene ether acrylate is as follows: Among them, R3 is ; 2≤x≤6; R2 is ; The structure of the dimer-based waterborne organosilicon-modified polyurethane acrylate prepolymer is as follows: ; Wherein, PU is R4 is ; R5 is Where 21≤c≤25; R6 is .

[0013] The aqueous photoinitiator is one or more of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, phenyl-2,4,6-trimethylbenzoyl lithium phosphite, Irgacure754, sodium benzophenone-4-carboxylate, and 4-acryloyloxybenzophenone. The cage-like polyhedral oligomeric silsesquioxanes include methacryloyloxypropyl cage-like polysilsesquioxanes.

[0014] The cashew phenol-based water-based transparent material further includes one or more of leveling agents, defoamers, or wetting and dispersing agents; The leveling agent is selected from one or more of BYK-333, BYK-UV3535, and BYK-354; The defoamer is selected from one or more of BYK-024, BYK-028, and TEGO Foamex 825; The wetting and dispersing agent is selected from one or more of BYK-190, BYK-346, and TEGO Wet 270; The leveling agent is present in a weight ratio of 0.5-2 parts; The defoamer is present in an amount of 0.5-2 parts by weight; The wetting and dispersing amount is 0.5-2 parts by weight.

[0015] The preparation method of the cashew phenol polyoxyethylene ether acrylate includes the following steps: Purified cashew phenol and alkali were placed under a protective atmosphere and ethylene oxide was introduced to carry out an ethoxylation reaction; then the pH of the reaction system was neutralized to 6.5-7.0, and dehydrated under vacuum to obtain cashew phenol polyoxyethylene ether. Cashew phenol polyoxyethylene ether is mixed with acrylic acid, p-toluenesulfonic acid, hydroquinone monomethyl ether and toluene water-carrying agent are added, and the mixture is refluxed to carry out the acrylate reaction to remove water and toluene, thereby obtaining cashew phenol polyoxyethylene ether acrylate. The preparation method of the dimer-based waterborne organosilicon-modified polyurethane acrylate prepolymer includes the following steps: Dimeric acid diol, polydimethylsiloxane diol and isophorone diisocyanate are mixed, a catalyst is added and a prepolymerization reaction is carried out; then dimethylolpropionic acid is added to continue the chain extension reaction; then hydroxyethyl acrylate is added to carry out the end-capping reaction; finally, triethylamine is added to neutralize the carboxyl groups to obtain the waterborne polyurethane acrylate prepolymer.

[0016] The alkali includes potassium hydroxide or sodium hydroxide; The amount of alkali added is 1.5-2.0 wt%; The protective atmosphere includes nitrogen; The temperature for the ethoxylation reaction is 120-150℃, and the pressure is no more than 0.4 MPa. The molar ratio of cashew phenol to ethylene oxide is 1:4-1:6; The acid used for neutralization includes glacial acetic acid; The cashew phenol polyoxyethylene ether and acrylic acid are in a hydroxyl:carboxyl molar ratio of 1:1.1-1:1.3; The content of p-toluenesulfonic acid is 1.0-1.5 wt%; The content of hydroquinone monomethyl ether is 0.8-1.2 wt%; The content of the toluene water-carrying agent is 30-40 wt%; The temperature for the acrylate esterification reaction is 110-140℃; The endpoint of the acrylate esterification reaction is an acid value of less than 5 mg KOH / g; The dimer acid diol and polydimethylsiloxane diol are mixed at a hydroxyl molar ratio of (2-10):1; When the isocyanate is mixed with the dimer glycol and polydimethylsiloxane diol, the isocyanate to hydroxyl molar ratio is 1.5-2.0:1. The catalyst includes dibutyltin dilaurate; The amount of hydroxyethyl acrylate added is 1.0-1.1 equivalents of the residual NCO molar amount; The end-capping reaction temperature is 70℃; The endpoint of the capping reaction is when the isocyanate content is less than 0.1%.

[0017] The method for preparing the cashew phenol-based aqueous transparent material includes the following steps: Methacryloxypropyl cage-like polysilsesquioxane was added to cashew phenol polyoxyethylene ether acrylate until completely dissolved to obtain a homogeneous oil phase premix. A waterborne polyurethane acrylate prepolymer emulsion is mixed with water to obtain a waterborne matrix mixture. The homogeneous oil phase premix was slowly added to the aqueous matrix mixture and emulsified by high-speed shearing to obtain a composite emulsion. Under light-protected conditions, the aqueous photoinitiator is added to the composite emulsion, stirred, and filtered to obtain the final product.

[0018] The high-speed shear emulsification speed is 800-1500 rpm; The filter screen has a mesh size of 0.05-1μm.

[0019] A water-based transparent coating is obtained by curing the aforementioned cashew phenol-based water-based transparent material under ultraviolet light.

[0020] The method for preparing the water-based transparent coating includes the following steps: The fruit phenol-based water-based transparent material of claim 1 is applied to the surface of a plasma-cleaned substrate by spraying, spin coating or dip coating to obtain a wet film; the moisture in the wet film is removed; and then it is cured by irradiation with ultraviolet light to obtain a water-based transparent coating.

[0021] The wet film thickness is 3-8 μm; The process of removing moisture from the wet film includes flash evaporation; The flash evaporation temperature is 50-70℃, and the time is 1-3 minutes; The wavelength of the ultraviolet light is 395 nm; The cumulative energy of the ultraviolet light is 500-2000 mJ / cm. 2 ; The thickness of the water-based transparent coating is 30-60 nm.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The cashew nut shell phenol-based waterborne transparent material provided by this invention comprises cashew nut shell phenol polyoxyethylene ether acrylate, dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer, cage-like polyhedral oligomeric silsesquioxane (POSS), photoinitiator, additives, and water. Cashew nut shell phenol possesses a unique rigid benzene ring framework and a C15 long-chain hydrophobic side chain structure, naturally exhibiting excellent low surface energy properties. The long chain and alicyclic structure of the dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer impart excellent hydrophobicity and scratch resistance to the coating. The cage-like structure of the cage-like polyhedral oligomeric silsesquioxane provides nanoscale hardness support.

[0023] The cashew nut shell phenol-based waterborne transparent material provided by this invention has a simple preparation method, is entirely water-based, and uses LED-UV curing. It requires no organic solvents, dries rapidly under UV irradiation, and consumes more than 80% less energy than traditional mercury lamps. The cashew nut shell phenol polyoxyethylene ether acrylate used in this invention is derived from cashew nut shell phenol extracted from agricultural waste in the processing industry, serving as a bio-based raw material. It can be obtained through only two steps (ethoxylation + acrylate esterification) to prepare a water-compatible photoactive monomer, with a relatively simple purification process. The dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer, through chemical methods, introduces bio-based dimer acids into the polyurethane main chain, resulting in a more economical and environmentally friendly structure. The prepared transparent coating material is fluorine-free and environmentally friendly.

[0024] The water-based transparent coating provided by this invention features high transparency, high hardness, wear resistance, and fingerprint resistance. It has a contact angle of over 115°, a transmittance of over 92%, a pencil hardness of 3H or higher, and can withstand over 1000 wear cycles. It also exhibits fingerprint resistance, requiring only two or fewer wipings with a tissue to remove fingerprints. Detailed Implementation

[0025] This invention provides a cashew nut shell phenol-based waterborne transparent coating material, comprising, by weight: 30-60 parts of dimer acid-based waterborne silicone-modified polyurethane acrylate prepolymer (D-WSPUA), 10-30 parts of cashew nut shell phenol polyoxyethylene ether acrylate (CPEA), 2-8 parts of polyhedral oligomeric silsesquioxane, 1-5 parts of waterborne photoinitiator, and 15-35 parts of deionized water. Other additives may also be included.

[0026] Preferably, the cashew phenol polyoxyethylene ether acrylate is prepared by a two-step reaction of cashew phenol extracted from cashew nut shells via ethoxylation and acrylate esterification, and its structure is -O-(CH2CH2O). x -CO-CH=CH2 is attached to the benzene ring of cashew nutshellol, where x = 2-6. The preparation method of cashew nutshellol-based photoactive monomer (CPEA) is as follows: a two-step reaction (ethoxylation + acrylate esterification): Ethoxylation reaction: 1 kg of cashew nut shell liquid was extracted with n-hexane to remove impurities and then distilled under reduced pressure (150-170℃, -0.095 MPa) to collect the cashew phenol fraction. The purified cashew phenol and 1.5-2.0 wt% potassium hydroxide were added to a high-pressure reactor. After nitrogen purging, the temperature was raised to 120-150℃, and ethylene oxide (EO) was introduced (cashew phenol:EO molar ratio 1:4-1:6). The pressure was controlled at ≤0.4 MPa and the reaction was carried out for 4-8 h. After cooling, the solution was neutralized with glacial acetic acid to pH 6.5-7.0 and dehydrated under vacuum (-0.095 MPa, 90℃, 1 h) to obtain cashew phenol polyoxyethylene ether (CE).

[0027] The specific reaction equation is as follows: Ethoxylation reaction: Where R1 is ; R2 is ; Where 2≤x≤6.

[0028] Acrylate esterification reaction: CE and acrylic acid are mixed at a hydroxyl:carboxyl molar ratio of 1:1.1-1:1.3, and 1.0-1.5wt% p-toluenesulfonic acid, 0.8-1.2wt% hydroquinone monomethyl ether and 30-40wt% toluene water-carrying agent are added. The mixture is refluxed at 110-140℃ for 4-6 hours, and water is removed by a water separator until the acid value is <5mg KOH / g. Toluene is removed by vacuum distillation to obtain cashew phenol polyoxyethylene ether acrylate (CPEA).

[0029] Among them, R3 is The dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer (D-WSPUA) is prepared by stepwise polymerization and neutralization emulsification of dimer acid glycol, polydimethylsiloxane diol, isophorone diisocyanate, dimethylolpropionic acid, and hydroxyethyl acrylate. The preparation method is as follows: Dimer acid glycol, polydimethylsiloxane diol, and isophorone diisocyanate are mixed at an NCO / OH molar ratio of 1.5-2.0:1 and reacted at 80°C with 0.1-0.2 wt% dibutyltin dilaurate as a catalyst for 2-4 hours; dimethylolpropionic acid (accounting for 8-12% of the total weight of polyol) is added and the reaction continues for 3 hours; then hydroxyethyl acrylate (accounting for 1.0-1.1 equivalents of the residual NCO) is added and the reaction is capped at 70°C for 2 hours. h, until NCO content <0.1%; cool to 40℃, neutralize carboxyl groups with triethylamine (neutralization degree 80-100%), add deionized water under high speed stirring to emulsify, and obtain waterborne polyurethane acrylate prepolymer (D-WSPUA) with solid content of 40-60%.

[0030] The specific equation is as follows: The equation for the reaction of dimer glycol, polydimethylsiloxane diol, and isophorone diisocyanate using dibutyltin dilaurate as a catalyst is as follows: Among them, R4 is ; R5 is , where c is 23; R6 is The reaction equation for the chain extension of DMPA, the reaction of the dihydroxyl group with NCO, and the introduction of -COOH into the side chain is as follows.

[0031] Wherein, PU is .

[0032] The reaction equation for HEA double bond capping (consuming residual NCO) is as follows: The reaction equation for the neutralization of triethylamine to form a salt is as follows: Preferably, the cage-like polyhedral oligomeric silsesquioxane is methacryloyloxypropyl cage-like polysilsesquioxane (MA-POSS), whose molecular formula can be represented as (CH2=C(CH3)COO(CH2)3SiO 1.5 )n, where n is 8, 10, or 12. The methacryloyloxypropyl cage-like polysilsesquioxane has a polyhedral cage-like silicon-oxygen framework structure, its inorganic core is composed of silicon-oxygen bonds (Si-O-Si), and its shell has multiple polymerizable methacrylate groups.

[0033] Preferably, the aqueous photoinitiator is one or a combination of two or more of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure 2959), phenyl-2,4,6-trimethylbenzoyl lithium phosphite (Irgacure TPO-L), Irgacure 754, sodium benzophenone-4-carboxylate, and 4-acryloyloxybenzophenone.

[0034] Preferably, the additives include one or more of leveling agents, defoamers, or wetting and dispersing agents.

[0035] Specifically, the leveling agent is one or more of BYK-333, BYK-UV3535, and BYK-354.

[0036] Specifically, the defoamer is one or more of BYK-024, BYK-028, and TEGO Foamex 825.

[0037] Specifically, the wetting and dispersing agent is one or more of BYK-190, BYK-346, and TEGO Wet 270.

[0038] This invention provides a method for preparing the above-mentioned coating material, comprising the following steps: Premixing and Dissolving: Methacryloxypropyl cage-like polysilsesquioxane (MA-POSS) is added to cashew phenol polyoxyethylene ether acrylate (CPEA) and stirred at 30-50℃ for 20-40 min until completely dissolved to obtain a homogeneous oil-phase premix. This step utilizes the structural similarity between cashew phenol polyoxyethylene ether acrylate (CPEA) and methacryloxypropyl cage-like polysilsesquioxane (MA-POSS) to form a molecular-level homogeneous solution of the cage-like structure of MA-POSS in the oil phase, providing a basis for the subsequent uniform introduction of a crosslinking network. At the same time, it ensures that the methacryloyl groups of MA-POSS and the acryloyl groups of CPEA are fully premixed before curing, ensuring their synergistic participation in free radical polymerization during UV curing.

[0039] Matrix preparation: Dimer acid-based waterborne silicone-modified polyurethane acrylate prepolymer (D-WSPUA) emulsion, deionized water and additives are mixed and stirred at 300-800 rpm for 10-30 min to obtain an aqueous matrix mixture. This step introduces dimer acid-based waterborne silicone-modified polyurethane acrylate prepolymer (D-WSPUA), whose C36 long chain and alicyclic structure endow the coating with excellent flexibility, hydrophobicity and scratch resistance. The D-WSPUA aqueous emulsion is uniformly mixed with additives and deionized water to construct a stable O / W type emulsion matrix with water as the continuous phase, providing a dispersion medium for the introduction of the oil phase premix.

[0040] Emulsification and composite: The homogeneous oil phase premix is ​​slowly added to the aqueous matrix mixture and emulsified at high speed of 800-1500 rpm for 10-40 min to obtain a composite emulsion; in this step, the oil phase premix containing MA-POSS is dispersed in the aqueous matrix through high speed shear emulsification, so that MA-POSS is uniformly distributed in the oil phase of the emulsion along with CPEA; the polyoxyethylene ether segments of CPEA help stabilize the oil phase droplets, while its C15 long-chain alkyl groups migrate and accumulate to the coating surface during the subsequent curing process, forming a low surface energy hydrophobic layer; Initiator formulation / filtration: Under light-protected conditions, the aqueous photoinitiator is added to the composite emulsion and stirred at 200-400 rpm for 10-30 min until homogeneous. The mixture is then filtered through a 0.05-1 μm capsule filter to obtain an aqueous UV-curable fluorine-free anti-fingerprint coating material. This step introduces an aqueous photoinitiator suitable for 395nm LED-UV curing systems; low-speed stirring in the dark avoids introducing air bubbles; and filtration removes impurities, resulting in a homogeneous and stable aqueous UV-curable coating material. The present invention also provides a coating and curing method for the above-mentioned coating material, the specific steps of which are as follows: The coating material is applied to the plasma-cleaned substrate surface via spraying, spin coating, or curtain coating, with the wet film thickness controlled at 3-8 μm; moisture is removed by flash evaporation at 50-70℃ for 1-3 min; subsequently, it is cured using a 395nm LED-UV curing device with a cumulative energy of 500-2000 mJ / cm². 2 Curing is performed to obtain a fluorine-free anti-fingerprint transparent coating with a thickness of 30-60nm, preferably 40-50nm.

[0041] The present invention will be further described below with reference to specific embodiments.

[0042] Examples and comparisons are as follows: In Examples 1-5 and Comparative Examples 1-3, the specific raw materials used in the preparation of cashew phenol-based waterborne UV-curable fluorine-free anti-fingerprint transparent coating materials are shown in Table 1 by weight. The numbers in Table 1 represent parts by weight.

[0043] Table 1 Example 1 Preparation steps: Premixed Dissolution: Dissolve 5g of methacryloyloxypropyl cage-like polysilsesquioxane MA-POSS (this compound is a cage-like mixture, its form is (CH2=C(CH3)COO(CH2)3SiO) 1.5 )8,(CH2=C(CH3)COO(CH2)3SiO 1.5 ) 10 and (CH2=C(CH3)COO(CH2)3SiO 1.5 ) 12 The mixture (CAS: 160185-24-0, Shanghai Maclean Biochemical Technology Co., Ltd.) was added to 20g CPEA and stirred at 40℃ for 25min until completely dissolved to obtain a homogeneous oil phase premix. Matrix preparation: Mix 45g D-WSPUA emulsion, 25g deionized water and 0.5g leveling agent BYK-UV3535, and stir at 500rpm for 15min to obtain an aqueous matrix mixture.

[0044] Emulsification and composite: The homogeneous oil phase premix is ​​slowly added to the aqueous matrix mixture and emulsified at a high speed of 1000 rpm for 20 min to obtain a composite emulsion; Initiator compounding / filtration: Under light-protected conditions, 3g of aqueous photoinitiator Irgacure 2959 was added to the composite emulsion and stirred at 300rpm for 10min until homogeneous. The mixture was then filtered through a 0.1μm capsule filter to obtain an aqueous UV-curable fluorine-free anti-fingerprint coating material.

[0045] The preparation method of cashew nut shell polyoxyethylene ether acrylate (CPEA) is as follows: 1 kg of cashew nut shell liquid is extracted with n-hexane to remove impurities and then distilled under reduced pressure (150℃, -0.095 MPa). The cashew nut shell fraction is collected. The purified cashew nut shell fraction is added to a high-pressure reactor with 1.5 wt% potassium hydroxide. After nitrogen purging, the temperature is raised to 120℃, and ethylene oxide (EO) is introduced (cashew nut shell fraction: EO molar ratio 1:4). The pressure is controlled at ≤0.4 MPa and the reaction is carried out for 5 h. After cooling, the pH is neutralized to 6.5 with glacial acetic acid and dehydrated under vacuum (-0.095 MPa, 90℃, 1 h) to obtain cashew nut shell polyoxyethylene ether (CE). CE and acrylic acid were mixed at a hydroxyl:carboxyl molar ratio of 1:1.1, and 1.2 wt% p-toluenesulfonic acid (p-TsOH, as a catalyst), 1.0 wt% hydroquinone monomethyl ether (MEHQ, as a polymerization inhibitor) and 30 wt% toluene water-carrying agent (Toluene, as a water-carrying agent) were added. The mixture was refluxed at 120 °C for 5 h, and water was removed using a water separator until the acid value was <5 mg KOH / g. Toluene was removed by vacuum distillation to obtain cashew phenol polyoxyethylene ether acrylate (CPEA).

[0046] The preparation method of D-WSPUA prepolymer emulsion is as follows: In the first stage reaction, dimer glycol, polydimethylsiloxane diol and isophorone diisocyanate (IPDI) are mixed at an NCO / OH molar ratio of 1.6:1 and reacted at 80°C with 0.1wt% dibutyltin dilaurate (DBTDL) for 3 hours; in the second stage reaction, dimethylolpropionic acid (DMPA, accounting for 10% of the total weight of polyols) is added and the reaction continues for 3 hours; in the third stage reaction, hydroxyethyl acrylate (HEA, accounting for 1.01 molar equivalents of residual NCO) is added and the reaction is capped at 70°C for 2 hours until the NCO content is <0.1%; in the fourth stage reaction, the temperature is lowered to 40°C, the carboxyl groups are neutralized with triethylamine (neutralization degree 90%), and deionized water is added under high-speed stirring for emulsification to obtain a waterborne polyurethane acrylate prepolymer (D-WSPUA) with a solid content of 45%.

[0047] Coating and Curing: The above coating material is applied to the glass surface cleaned by O2 plasma via spraying, with the wet film thickness controlled at 3-8 μm. Moisture is removed by flash evaporation at 60℃ for 2 minutes, followed by curing with a 395 nm LED-UV system (light intensity 2000 mW / cm²). 2 ), with a cumulative energy of 800 mJ / cm 2 Curing is performed to obtain a fluorine-free, fingerprint-resistant transparent coating with a dry film thickness of 40-50 nm.

[0048] Example 2 The difference between Example 2 and Example 1 is that the amount of CPEA is increased to 25 parts, and the amount of deionized water is reduced to 20 parts. The remaining components and preparation steps are the same as in Example 1. This formulation increases the proportion of bio-based active diluent, resulting in better coating flexibility, making it suitable for applications with high requirements for bending performance, such as flexible folding screens.

[0049] Example 3 The difference between Example 3 and Example 1 is that the amount of MA-POSS is increased to 8 parts, and the amount of deionized water is reduced to 22 parts. The remaining components and preparation steps are the same as in Example 1. This formulation increases the proportion of organic-inorganic hybrid reinforcing phase, further improving the coating hardness and wear resistance, making it suitable for applications requiring high weather resistance, such as automotive displays.

[0050] Example 4 The difference between Example 4 and Example 1 is that the amount of aqueous photoinitiator Irgacure 2959 is increased to 4 parts, and the amount of deionized water is reduced to 24 parts. The remaining components and preparation steps are the same as in Example 1. This formulation increases the photoinitiator concentration, resulting in faster coating curing speed and shorter surface drying time, making it suitable for high-speed continuous production lines.

[0051] Example 5 The difference between Example 5 and Example 1 is that the amount of D-WSPUA is increased to 50 parts, CPEA is reduced to 15 parts, MA-POSS is increased to 6 parts, and deionized water is 24 parts. The remaining components and preparation steps are the same as in Example 1. This formulation is a comprehensive optimization, taking into account high hydrophobicity, high permeability, and high hardness and wear resistance.

[0052] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that CPEA is not added, and an equal amount of hydroxyethyl acrylate (HEA) is used instead as the reactive diluent. The remaining components and preparation steps are the same as in Example 1. This comparative example is used to verify the contribution of cashew nut shell phenolic photoactive monomers to the low surface energy and anti-fingerprint properties of the coating.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that MA-POSS is not added, and the amount of deionized water is increased to 30 parts. The remaining components and preparation steps are the same as in Example 1. This comparative example is used to verify the contribution of cage-type POSS to the coating hardness, abrasion resistance, and light transmittance.

[0054] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that D-WSPUA is not added; instead, an equal amount of conventional polyether-based waterborne polyurethane acrylate prepolymer (WPUA) is used instead. The remaining components and preparation steps are the same as in Example 1. This comparative example is used to verify the contribution of dimer-based waterborne silicone-modified polyurethane acrylate prepolymer to the hydrophobicity, flexibility, and scratch resistance of the coating.

[0055] As described above, the preparation methods and structural formulas of CPEA and D-WSPUA in Examples 2-5 and Comparative Examples 1-3 are the same as those in Example 1.

[0056] The coating materials prepared in Examples 1-5 and Comparative Examples 1-3 were used to prepare coating samples according to the coating and curing method described in Example 1, and the following performance tests were performed.

[0057] 1) Contact angle test The water contact angle and n-hexadecane contact angle of the coating were measured using a standard contact angle meter. 3 μL of deionized water and 3 μL of n-hexadecane were dropped onto the coating surface, and the contact angle values ​​after stabilization were read. The results are shown in Table 2.

[0058] Table 2 As shown in Table 2, the water contact angles of Examples 1-5 all reached over 115°, and the contact angles of n-hexadecane reached over 65°, which were significantly better than those of Comparative Example 1 (without CPEA) (98° and 52°) and Comparative Example 3 (with WPUA instead of D-WSPUA) (108° and 60°). This demonstrates that the cashew phenol-based photoactive monomer plays a key role in improving the hydrophobic and oleophobic properties of the coating surface. Meanwhile, the data of Comparative Example 3 were lower than those of the Examples, indicating that the PDMS segments and the C36 dimer chain in D-WSPUA also made important contributions to improving the hydrophobic and oleophobic properties of the coating.

[0059] 2) Transmittance and Haze Test The transmittance and haze value of the coating at 550 nm were measured using a UV-Vis spectrophotometer and a haze meter, respectively. The results are shown in Table 3.

[0060] Table 3 As shown in Table 3, the transmittance of Examples 1-5 is greater than 92%, and the haze is less than 0.5%, which is slightly better than the comparative examples. Comparative Example 2, which does not contain MA-POSS, has a transmittance of 91.9%, which is also close to that of the examples. This indicates that MA-POSS is uniformly distributed in the cross-linked network through chemical bonding, avoiding the aggregation problem of physically blended nanoparticles, thus ensuring the high transparency of the coating. Comparative Example 3 (using WPUA instead of D-WSPUA) has a transmittance of 91.2% and a haze of 0.6%, which is close to but slightly lower than the examples, indicating that D-WSPUA has good compatibility with CPEA and MA-POSS and does not cause significant light scattering.

[0061] 3) Anti-fingerprint performance test The artificial fingerprint liquid consists of 95% artificial sweat and 5% artificial sebum. The artificial sweat is prepared by mixing 3 mL / L lactic acid, 5 mL / L acetic acid, 10 g / L sodium chloride, 10 g / L sodium hydrogen phosphate, and deionized water. The artificial sebum consists of oleic acid (2%), stearic acid (2%), and squalene (1%). A small amount of nonionic surfactant is added after mixing the artificial sweat and artificial sebum to overcome the natural immiscibility between sweat and sebum.

[0062] Test method: First, clean your fingers with alcohol, immerse your fingers in artificial fingerprint liquid, then touch the coating surface to form a fingerprint, and then wipe with a white paper towel at a speed of 3cm / s under a pressure of 500g. Record the number of wipings that can make the fingerprint disappear. The results are shown in Table 4.

[0063] Table 4 As shown in Table 4, Examples 1-5 all removed fingerprints within two wiping cycles, demonstrating excellent anti-fingerprint performance. In contrast, Comparative Example 1 (without CPEA) required four wiping cycles, while Comparative Example 2 (without MA-POSS) and Comparative Example 3 (using WPUA instead of D-WSPUA) both required three wiping cycles. This demonstrates that the low surface energy C15 long chain of CPEA and the nanoscale surface roughness of MA-POSS synergistically enhance the anti-fingerprint effect. Furthermore, the data from Comparative Example 3 shows that the PDMS segments and dimer acid C36 long chains in D-WSPUA also significantly contribute to maintaining the anti-fingerprint performance of the coating.

[0064] 4) Pencil hardness test According to ASTM D3363 standard, pencil hardness was tested under a 1kg load, and the results are shown in Table 5.

[0065] Table 5 As shown in Table 5, the pencil hardness of Examples 1-5 all reached 3H or higher, with Example 3 (increased MA-POSS content) reaching 4H. Comparative Example 2 (without MA-POSS) was H, demonstrating that the cage structure of MA-POSS plays a decisive role in improving the coating hardness; meanwhile, the data from Comparative Example 3 shows that the dimer ester ring structure in D-WSPUA also plays an important role in maintaining the coating hardness.

[0066] 5) Abrasion resistance test Using 0000# steel wool, the coating surface was rubbed reciprocally under a 1 kg load. The water contact angle was recorded every 100 rubs, and failure occurred when the contact angle decreased by more than 10°. The results are shown in Table 6.

[0067] Table 6 As shown in Table 6, the wear resistance of Examples 1-5 all exceeded 1000 cycles, with Example 3 showing only a 2° decrease after more than 2000 cycles. Comparative Example 2 (without MA-POSS) failed after only 300 cycles, demonstrating that the organic-inorganic hybrid network formed by MA-POSS through chemical bonding significantly improves the wear resistance and durability of the coating. Comparative Example 3 (using WPUA instead of D-WSPUA) failed after 800 cycles, indicating that the toughening effect of the dimer acid C36 long chain and alicyclic structure in D-WSPUA, combined with the lubrication effect of the PDMS segments, synergistically improves the wear resistance and durability of the coating.

[0068] 6) Surface drying time test 395nm LED-UV curing equipment (light intensity 2000 mW / cm²) was used. 2 The cumulative energy required for the coating to reach surface dryness was recorded. The surface dry times for Examples 1-5 were all between 1.5 and 2.5 seconds (corresponding to approximately 500-800 mJ / cm²). 2 In Example 4, the content of water-based photoinitiator is higher, and it only takes 1.5 seconds to cure. The surface drying time of Comparative Example 3 (with WPUA instead of D-WSPUA) is about 2.5 seconds, which is comparable to the Example 4. This shows that the introduction of D-WSPUA does not affect the curing speed and is significantly faster than the 5-10 seconds of the traditional mercury lamp curing system.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A cashew nut phenol-based water-based transparent material, characterized in that: By weight, it includes 30-60 parts of dimer acid-based waterborne organosilicon-modified polyurethane acrylate prepolymer, 10-30 parts of cashew phenol polyoxyethylene ether acrylate, 2-8 parts of polyhedral oligomeric silsesquioxane, 1-5 parts of waterborne photoinitiator and 15-35 parts of water. The structure of the cashew phenol polyoxyethylene ether acrylate is as follows: Among them, R3 is ; 2≤x≤6; R2 is ; The structure of the dimer-based waterborne organosilicon-modified polyurethane acrylate prepolymer is as follows: ； Wherein, PU is R4 is ; R5 is Where 21≤c≤25; R6 is .

2. The cashew nut phenol-based water-based transparent material as described in claim 1, characterized in that: The aqueous photoinitiator is one or more of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, phenyl-2,4,6-trimethylbenzoyl lithium phosphite, Irgacure754, sodium benzophenone-4-carboxylate, and 4-acryloyloxybenzophenone. The cage-like polyhedral oligomeric silsesquioxanes include methacryloyloxypropyl cage-like polysilsesquioxanes.

3. The cashew nut phenol-based water-based transparent material as described in claim 1, characterized in that: It also includes one or more of leveling agents, defoamers, or wetting and dispersing agents; The leveling agent is selected from one or more of BYK-333, BYK-UV3535, and BYK-354; The defoamer is selected from one or more of BYK-024, BYK-028, and TEGO Foamex 825; The wetting and dispersing agent is selected from one or more of BYK-190, BYK-346, and TEGO Wet 270; The leveling agent is present in a weight ratio of 0.5-2 parts; The defoamer is present in an amount of 0.5-2 parts by weight; The wetting and dispersing amount is 0.5-2 parts by weight.

4. The cashew phenol-based water-based transparent material as described in claim 2, characterized in that: The preparation method of the cashew phenol polyoxyethylene ether acrylate includes the following steps: Purified cashew phenol was reacted with alkali under a protective atmosphere and ethylene oxide was introduced to carry out an ethoxylation reaction; then the pH of the reaction system was neutralized to 6.5-7.0, and dehydrated under vacuum to obtain cashew phenol polyoxyethylene ether. Cashew phenol polyoxyethylene ether is mixed with acrylic acid, p-toluenesulfonic acid, hydroquinone monomethyl ether and toluene water-carrying agent are added, and the mixture is refluxed to carry out the acrylate reaction to remove water and toluene, thereby obtaining cashew phenol polyoxyethylene ether acrylate. The preparation method of the dimer-based waterborne organosilicon-modified polyurethane acrylate prepolymer includes the following steps: Dimeric acid diol, polydimethylsiloxane diol and isophorone diisocyanate are mixed, a catalyst is added and a prepolymerization reaction is carried out; then dimethylolpropionic acid is added to continue the chain extension reaction; then hydroxyethyl acrylate is added to carry out the end-capping reaction; finally, triethylamine is added to neutralize the carboxyl groups to obtain the waterborne polyurethane acrylate prepolymer.

5. The cashew phenol-based water-based transparent material as described in claim 4, characterized in that: The alkali includes potassium hydroxide or sodium hydroxide; The amount of alkali added is 1.5-2.0 wt%; The protective atmosphere includes nitrogen; The temperature for the ethoxylation reaction is 120-150℃, and the pressure is no more than 0.4 MPa. The molar ratio of cashew phenol to ethylene oxide is 1:4-1:6; The acid used for neutralization includes glacial acetic acid; The cashew phenol polyoxyethylene ether and acrylic acid are in a hydroxyl:carboxyl molar ratio of 1:1.1-1:1.

3. The content of p-toluenesulfonic acid is 1.0-1.5 wt%; The content of hydroquinone monomethyl ether is 0.8-1.2 wt%; The content of the toluene water-carrying agent is 30-40 wt%; The temperature for the acrylate esterification reaction is 110-140℃; The endpoint of the acrylate esterification reaction is an acid value of less than 5 mg KOH / g; The dimer acid diol and polydimethylsiloxane diol are mixed at a hydroxyl molar ratio of (2-10):1; When the isocyanate is mixed with the dimer glycol and polydimethylsiloxane diol, the isocyanate to hydroxyl molar ratio is 1.5-2.0:

1. The catalyst includes dibutyltin dilaurate; The amount of hydroxyethyl acrylate added is 1.0-1.1 equivalents of the residual NCO molar amount; The end-capping reaction temperature is 70℃; The endpoint of the capping reaction is when the isocyanate content is less than 0.1%.

6. The method for preparing the cashew phenol-based waterborne transparent material as described in claim 1, characterized in that: Includes the following steps: Methacryloxypropyl cage-like polysilsesquioxane was added to cashew phenol polyoxyethylene ether acrylate until completely dissolved to obtain a homogeneous oil phase premix. A waterborne polyurethane acrylate prepolymer emulsion is mixed with water to obtain a waterborne matrix mixture. The homogeneous oil phase premix was slowly added to the aqueous matrix mixture and emulsified by high-speed shearing to obtain a composite emulsion. Under light-protected conditions, the aqueous photoinitiator is added to the composite emulsion, stirred, and filtered to obtain the final product.

7. The method for preparing the cashew phenol-based waterborne transparent material as described in claim 1, characterized in that: The high-speed shear emulsification speed is 800-1500 rpm; The filter screen has a mesh size of 0.05-1μm.

8. A water-based transparent coating; characterized in that: It is obtained by curing the cashew phenol-based water-based transparent material as described in claim 1 under ultraviolet light irradiation.

9. The method for preparing the water-based transparent coating as described in claim 8, characterized in that: Includes the following steps: The fruit phenol-based water-based transparent material of claim 1 is applied to the surface of a plasma-cleaned substrate by spraying, spin coating or dip coating to obtain a wet film; the moisture in the wet film is removed; and then it is cured by irradiation with ultraviolet light to obtain a water-based transparent coating.

10. The method for preparing the water-based transparent coating as described in claim 9, characterized in that: The wet film thickness is 3-8 μm; The process of removing moisture from the wet film includes flash evaporation; The flash evaporation temperature is 50-70℃, and the time is 1-3 minutes; The wavelength of the ultraviolet light is 395 nm; The cumulative energy of the ultraviolet light is 500-2000 mJ / cm. 2 ; The thickness of the water-based transparent coating is 30-60 nm.

Images