Multi-hydroxyl crosslinking modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin, preparation method and application thereof

Abstract

The application discloses a multi-hydroxyl cross-linking modified core-shell structure water-based polyurethane / acrylate hybrid anti-glare resin and a preparation method and application thereof. The preparation method comprises the following steps: under the protection of nitrogen, dimethylol propionic acid, polyether polyol, xylitol and aliphatic diisocyanate are uniformly mixed, an organic tin catalyst is added to prepare a multi-hydroxyl cross-linking modified polyurethane prepolymer, then an unsaturated monomer containing a hydroxyl group is added, an excess of a compound with a hydroxyl functional group is added to prepare a carbon-carbon double bond capped polyurethane prepolymer, and then a neutralizing agent, deionized water, an acrylate monomer and a free radical initiator are added to prepare a target product; the hybrid resin prepared by the application has excellent anti-glare performance and mechanical properties and the characteristics of a core-shell structure, can make up for the deficiency of the water-based polyurethane, and can be applied to decorative coatings as an anti-glare coating.

Description

Technical Field

[0001] This invention relates to an anti-glare resin, specifically to a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin, its preparation method, and its application. Background Technology

[0002] With the continuous progress of the times, mobile phones, computers and tablets have become increasingly popular. People use electronic devices for a long time, resulting in longer and longer viewing times on screens. This long-term use will affect the health of the visual system. Especially in strong light environments, the surface of objects will produce strong specular reflections, resulting in glare. This will make the image blurry when users view screens or other optical devices, and may even cause visual problems such as temporary blindness. Glare is a serious form of light pollution that can affect or even harm people's daily lives. Common glare hazards include: (1) Architectural lighting: In modern buildings, most lighting equipment uses LED light sources. These light sources have the characteristics of concentrated light and bright colors, and usually lack reflectors, resulting in excessively strong light entering the eyes, which can easily cause direct damage to the eyes. (2) Road traffic: In road traffic, the headlights of vehicles are bright and have a long illumination distance. At the same time, the lights on both sides of the road and the night scene lighting will also cause interference. In dim light environments, drivers' visual ability is prone to decline, which may lead to visual fatigue, and in severe cases, may even lead to traffic accidents. (3) Screens: With the popularization of electronic devices, the frequency of screen use is increasing. However, most displays on the market currently suffer from glare problems. Prolonged use can easily lead to eye fatigue and may even cause eye diseases such as myopia and glaucoma. With the increasing public awareness of health, soft and clear surfaces are gradually becoming a hot research topic.

[0003] Waterborne polyurethane is widely used to solve the "glare" problem due to its unique gloss properties. The anti-glare mechanism mainly involves creating numerous depressions and undulations (not surface defects) on the substrate surface. This enhances the interaction between diffuse reflection and light scattering when light hits the substrate, resulting in an anti-glare effect. There are two methods to achieve anti-glare with waterborne polyurethane. One is by adding physical additives; however, this method is costly and environmentally unfriendly and has long been phased out. The other method is to chemically modify the inherent properties of the waterborne polyurethane itself to achieve an anti-glare effect. This modification can regulate the molecular structure of the waterborne polyurethane, creating a rough microstructure on the surface, thereby achieving a better and more stable anti-glare effect. This method is currently the most commonly used.

[0004] However, waterborne polyurethane still has some drawbacks, such as poor mechanical properties, low chemical resistance, poor hydrolysis resistance, and high cost. Acrylic esters, on the other hand, have advantages such as good weather resistance, excellent alkali resistance, and low price. Therefore, acrylate modification can effectively overcome the shortcomings of waterborne polyurethane. Furthermore, this invention uses a seed emulsion polymerization method to organically combine waterborne polyurethane and acrylate, forming a unique core-shell structured nanosphere. This microsphere has a waterborne polyurethane shell and an acrylate core, giving it specific physical and chemical properties. This core-shell structure can significantly improve the surface roughness of the waterborne polyurethane / acrylate hybrid resin, helping to enhance the optical performance of the coating. Secondly, it makes the emulsion more stable, avoiding phase separation and precipitation. In addition, this method can also make the particle size more uniform, effectively enhancing the optical performance of the coating and achieving the requirements for anti-glare.

[0005] The cross-linking structure between hybrid polymers significantly affects the gloss, water resistance, solvent resistance, and mechanical properties of coatings. Therefore, adding a suitable cross-linking agent to form a cross-linking structure can effectively improve the optical and mechanical properties of the coating. One of the most important and practical modification methods for waterborne polyurethane / acrylate hybrid resins is internal cross-linking modification. Commonly used cross-linking agents are mostly alcohols and amines, such as xylitol and diethylenetriamine. However, amine cross-linking agents have very strict requirements for reaction conditions such as temperature and humidity. Furthermore, after cross-linking with amines, their flexibility is greatly reduced, leading to easy breakage. In addition, most amine cross-linking agents are highly toxic and irritating, harmful to human health and the environment. In contrast, alcohol cross-linking agents have milder reaction conditions, moderate reaction rates, and less exothermic reactions. On the other hand, after cross-linking, they form a more flexible cross-linked network, giving the coating good flexibility and impact resistance. Many alcohol cross-linking agents are relatively non-toxic or low-toxic, without a noticeable irritating odor, making them suitable as cross-linking agents for the internal cross-linking modification of waterborne polyurethane / acrylate hybrid resins. However, we often use commonly used alcohol crosslinking agents, such as trimethylolpropane, and lack research and application of other alcohol crosslinking agents. Different types of alcohol crosslinking agents (such as monohydric alcohols, dihydric alcohols, or polyhydric alcohols) contain different numbers of crosslinking functional groups and different spatial configurations, which affect the degree of crosslinking reaction and further affect the optical and mechanical properties of the coating. This invention studies the effects of different types of alcohol crosslinking agents on the optical and mechanical properties of the coating, and ultimately finds that the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin prepared by xylitol crosslinking modification has the best optical and mechanical properties.

[0006] Chinese invention patent CN2019101586198 discloses a waterborne self-matting acrylate-modified polyurethane resin. This technology first prepares an acrylic emulsion containing amino groups, then mixes it with a capped polyurethane prepolymer to carry out a chain extension reaction. However, the preparation of the polyurethane prepolymer requires a large amount of organic solvent, and subsequent processing will have a significant environmental impact. Furthermore, because the waterborne polyacrylate emulsion and the hydrophobic polyurethane prepolymer are difficult to fully mix physically, the reaction may be incomplete, resulting in uneven particle size and affecting the coating performance.

[0007] Chinese invention patent CN2016108590294 discloses a waterborne polyurethane anti-glare coating material and its preparation method. This technology uses a stepwise polymerization of waterborne polyurethane prepolymer and a two-step chain-extended emulsification process to prepare a waterborne polyurethane anti-glare emulsion, resulting in a coating that simultaneously exhibits low gloss and high light transmittance. However, using waterborne polyurethane for preparation results in higher costs, and its mechanical properties, chemical resistance, and hydrolysis resistance still need improvement, making it difficult to obtain a coating with excellent overall performance. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of waterborne polyurethane coatings, such as poor flexibility, low tensile strength, weak hydrolysis resistance, and high cost. It provides an environmentally friendly, high-performance, and solvent-free anti-glare waterborne polyurethane / acrylate hybrid resin and its preparation method.

[0009] Another object of the present invention is to provide the application of the aforementioned multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin in the preparation of anti-glare coatings. This anti-glare coating can be used on glass substrates and automotive paint films, achieving an anti-glare effect.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A method for preparing a multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin comprises the following steps:

[0012] 1) Under nitrogen protection, dimethylolpropionic acid, polyether polyol, xylitol and aliphatic diisocyanate are mixed evenly, an organotin catalyst is added and reacted at 60-65℃ for 1-1.5h, and then the temperature is raised to 80-85℃ for 2-2.5h to prepare polyhydroxy crosslinked modified polyurethane prepolymer.

[0013] 2) Add an unsaturated monomer containing hydroxyl groups to the polyhydroxy crosslinked modified polyurethane prepolymer, cool to 60-70℃ and react for 3-4 hours, then add an excess of a compound with hydroxyl functional groups to react completely, so as to obtain a carbon-carbon double bond-terminated polyurethane prepolymer.

[0014] 3) Add a neutralizing agent to the obtained carbon-carbon double bond-terminated polyurethane prepolymer, and cool to 35-45℃ to react, thereby obtaining a polyurethane prepolymer with carboxylate anions.

[0015] 4) Add deionized water to the obtained polyurethane prepolymer with carboxylate anions, stir at high speed, and react at room temperature for 15-30 min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0016] 5) Add acrylate monomers to the obtained multi-hydroxy crosslinked modified waterborne polyurethane emulsion, heat to 75-80℃, stir evenly, add free radical initiator to react, and obtain multi-hydroxy crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin.

[0017] To further achieve the objectives of this invention, preferably, the raw materials are, by mass percentage, as follows: 25%–35% polyether polyol, 1%–2% dimethylolpropionic acid, 0.2%–0.8% xylitol, 15%–25% aliphatic diisocyanate, 0.03%–0.06% organotin catalyst, 5%–8% unsaturated monomers containing hydroxyl groups, 1.5%–3% compounds with hydroxyl functional groups, 0.6%–1.4% neutralizing agent, 10%–50% acrylic monomers, 0.2%–0.4% free radical initiator, and the balance being deionized water.

[0018] Preferably, in step 1), the polyether polyol is one or more of polypropylene glycol, polypropylene triol, and polytetrahydrofuran glycol; the aliphatic diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, and lysine diisocyanate; and the organotin catalyst is one or more of dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, and di(dodecyl sulfide)dibutyltin.

[0019] Preferably, in step 2), the reaction time for adding an excess of the compound with hydroxyl functional groups is 0.5 to 1 hour; the complete NCO reaction is controlled by measuring the NCO group content in the prepolymer every 0.5 to 1 hour during the reaction process using the di-n-butylamine method.

[0020] Preferably, in step 2), the unsaturated monomer containing hydroxyl groups is one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; the compound with hydroxyl functional groups is one or more of n-pentanol, n-butanol, and isopropanol.

[0021] Preferably, the reaction time for cooling to 35-45°C is 0.5-1 hour; the neutralizing agent is one or more of ammonia, potassium hydroxide, triethylamine, sodium bicarbonate, and sodium acetate.

[0022] Preferably, in step 4), the stirring rate of the high-speed stirring is 2000-3000 r / min.

[0023] Preferably, in step 5), the reaction time for adding the free radical initiator is 6-7 hours; the acrylic monomer is one or more of methyl methacrylate, butyl acrylate, methyl 2-methacrylate, and ethyl 2-methacrylate; the free radical initiator is one or more of potassium persulfate, ammonium persulfate, and azobisisobutyronitrile; and the stirring speed for uniform stirring is 200-300 r / min.

[0024] A cross-linked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin is prepared by the above-described preparation method.

[0025] The application of the aforementioned multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin in the preparation of anti-glare coatings. This coating can be used on any glass substrate surface and automotive paint films to achieve an anti-glare effect.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) The polyurethane / acrylate hybrid anti-glare resin of this invention is a type of nanosphere at the microscopic level. This nanosphere is a core-shell structured nanosphere with waterborne polyurethane as the "shell" and acrylate as the "core". This core-shell structured nanosphere is obtained by seed emulsion polymerization. While retaining the original optical properties of waterborne polyurethane, it effectively integrates the excellent weather resistance and alkali resistance of acrylate and its low price into the waterborne polyurethane system, so that the coating has good comprehensive performance and also has a price advantage.

[0028] 2) This invention, based on acrylate modification with the addition of acrylate monomers, introduces a hydroxyl crosslinking agent to improve the optical and mechanical properties of the coating. Xylitol, as a polyhydroxyl crosslinking agent, has hydroxyl groups that can react with isocyanate groups. Therefore, the addition of xylitol will create many crosslinking sites in the system. After high crosslinking, the waterborne polyurethane can better form a dense crosslinked network structure, increasing the rigidity of the formed latex particles. As the film is dried and prepared, the particle morphology can be better maintained, thus maintaining good anti-glare performance.

[0029] 3) This invention uses alcohol-based crosslinking agents for crosslinking modification. These crosslinking agents form a relatively flexible crosslinking network after crosslinking, giving the coating good flexibility and impact resistance. At the same time, the reaction conditions are relatively mild, the reaction rate is moderate, and the heat release is low. On the other hand, many alcohol-based crosslinking agents are relatively non-toxic or low-toxic, have no obvious irritating odor, and have environmental and safety value.

[0030] 4) This invention uses an aqueous seed emulsion polymerization method, without adding any organic reagents, and there is no subsequent step of removing organic solvents from the product, which is very environmentally friendly and energy-saving.

[0031] 5) In the process of preparing the emulsion, the present invention uses a high-speed stirrer to stir at a speed of 2000 r / min, which can prepare nanoparticles with a particle size of 300-800 nm, and can meet the requirements of anti-glare without adding any additives. Attached Figure Description

[0032] Figure 1 The infrared spectrum of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of this invention is shown.

[0033] Figure 2 This is a particle size distribution diagram of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of the present invention.

[0034] Figure 3 This is a scanning electron microscope (SEM) image of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of the present invention.

[0035] Figure 4 The stress-strain curve is shown for the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of this invention.

[0036] Figure 5 This is a transmittance diagram of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of the present invention.

[0037] Figure 6 This is a transmission electron microscope (TEM) image of the multihydroxy crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin prepared in Example 1 of this invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0039] This invention introduces a hydroxyl crosslinking agent to improve the optical and mechanical properties of the coating. Therefore, the preparation of the polyurethane prepolymer modified with multi-hydroxyl crosslinking involves uniformly mixing dimethylolpropionic acid, polyether polyol, xylitol, and aliphatic diisocyanate under nitrogen protection, followed by the addition of an organotin catalyst. Xylitol contains a large number of hydroxyl groups, which can react with isocyanate. The addition of xylitol creates numerous crosslinking sites in the system, allowing for crosslinking modification with the waterborne polyurethane. After high crosslinking, the waterborne polyurethane acts as the outer "shell," forming a dense crosslinked network that tightly aggregates particles, increasing the rigidity of the resulting latex particles. The waterborne polyurethane can better encapsulate the acrylate, forming more uniform nanospheres. As the coating is prepared, the particle morphology is better maintained. When light shines on the coated glass surface, due to the presence of these rough structures, most of the light undergoes diffuse reflection and refraction, with only a small portion directly reflected to the eye, effectively reducing the gloss of the coating surface and demonstrating excellent anti-glare capability.

[0040] The present invention discloses a method for preparing a multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin, characterized by comprising the following steps:

[0041] 1) Under nitrogen protection, dimethylolpropionic acid, polyether polyol, xylitol and aliphatic diisocyanate are mixed evenly, an organotin catalyst is added and reacted at 60-65℃ for 1-1.5h, and then the temperature is raised to 80-85℃ for 2-2.5h to prepare polyhydroxy crosslinked modified polyurethane prepolymer.

[0042] 2) Add an unsaturated monomer containing hydroxyl groups to the polyhydroxy crosslinked modified polyurethane prepolymer, cool to 60-70℃ and react for 3-4 hours, then add an excess of a compound with hydroxyl functional groups to react completely, so as to obtain a carbon-carbon double bond-terminated polyurethane prepolymer.

[0043] 3) Add a neutralizing agent to the obtained carbon-carbon double bond-terminated polyurethane prepolymer, and cool to 35-45℃ to react, thereby obtaining a polyurethane prepolymer with carboxylate anions.

[0044] 4) Add deionized water to the obtained polyurethane prepolymer with carboxylate anions, stir at high speed, and react at room temperature for 15-30 min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0045] 5) Add acrylate monomers to the obtained multi-hydroxy crosslinked modified waterborne polyurethane emulsion, heat to 75-80℃, stir evenly, add free radical initiator to react, and obtain multi-hydroxy crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin.

[0046] The multi-hydroxy crosslinked modified core-shell waterborne polyurethane / acrylate hybrid anti-glare resin prepared by this invention has a core-shell structure with polyurethane as the shell and acrylate as the core; and a multi-hydroxy crosslinking agent is used to crosslink the waterborne polyurethane, so that the waterborne polyurethane, which serves as the "shell", is highly crosslinked, resulting in increased rigidity of the latex particles and good anti-glare performance of the film.

[0047] The test descriptions involved in the examples are as follows:

[0048] 1) Coating preparation method: According to GB / T 1727-2021 standard, the above-prepared anti-glare waterborne polyurethane / acrylate hybrid emulsion was coated onto the glass substrate using an RDS linear coating rod. The film thickness was (35±5)μm. Then, it was placed in a 40℃ digital display high-temperature drying oven for 24h, and then taken out and cooled, and placed in a desiccator for later use.

[0049] 2) Coating gloss: According to ISO / 2813 standard, with glass as the substrate of the coating, the 60° gloss of the coating was measured using a 500MC gloss meter from Erichsen GmbH, Germany.

[0050] 3) Emulsion particle size: The hybrid emulsion was tested using an LA-960V2 laser particle size distribution analyzer. The emulsion was diluted with deionized water to a solid content of about 1 wt% and added dropwise to the sample cell.

[0051] 4) Mechanical properties of the coating: After the coating is cut according to GB / T 528-2009, its mechanical properties are tested on a UT-2080 tensile testing machine at a tensile rate of 200 mm / min.

[0052] 5) Water Absorption Rate: The coating film was tested according to HG / T 3344-2012. A suitable amount of dried coating film was weighed and recorded as W1. The coating film was then immersed in excess deionized water until constant weight was achieved. The sample was then removed and the surface moisture was wiped off with absorbent paper; the weight of the sample at this point was recorded as W2. Water Absorption Rate (W a The calculation formula is as follows:

[0053]

[0054] 6) Transmittance: Using a blank glass substrate as a reference, the transmittance of the coating on the transparent glass substrate was tested using a UV-3600 ultraviolet-visible absorption spectrometer, with a scanning range of 350-800nm.

[0055] 7) Pencil hardness: The hardness of the coating film was determined according to the pencil method of paints and varnishes in GB / T6739-2006.

[0056] Example 1

[0057] 1) Under nitrogen protection, 2.73g of dimethylolpropionic acid, 62.8g of polytetrahydrofuran diol, 0.95g of xylitol and 39.55g of isophorone diisocyanate were placed in a constant temperature water bath and mixed evenly. 0.06g of dibutyltin dilaurate was added and reacted at 60℃ for 1h. Then the temperature was raised to 80℃ and reacted for 2.5h to prepare polyhydroxy crosslinked modified polyurethane prepolymer.

[0058] 2) Add 12.87g of hydroxyethyl acrylate to the polyhydroxy crosslinked modified polyurethane prepolymer obtained in step 1), cool to 65℃ and react for 3h. During the reaction, the NCO group content in the prepolymer is determined by the di-n-butylamine method every 1h. Then add 3.52g of n-butanol and react for 1h to ensure that the NCO reaction is complete and carbon-carbon double bond-terminated polyurethane prepolymer is obtained.

[0059] 3) Add 2.06g of triethylamine to the carbon-carbon double-bond-terminated polyurethane prepolymer obtained in step 2) to neutralize it, cool to 35℃ and react for 0.5h to obtain a polyurethane prepolymer with carboxylate anions.

[0060] 4) Slowly add 476.01g of deionized water to the polyurethane prepolymer with carboxylate anions obtained in step 3), while stirring at a high speed of 3000r / min, and then react at room temperature for 30min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0061] 5) Add 80.01g of methyl methacrylate to the waterborne polyurethane emulsion obtained in step 4), heat to 75℃, stir evenly at a stirring rate of 200r / min, then add 0.46g of azobisisobutyronitrile and react for 6h to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare emulsion.

[0062] 6) The emulsion obtained in step 5) was uniformly coated onto a glass slide using an RDS linear coating tool. The slide was then placed in a 40°C forced-air high-temperature drying oven for 24 hours. After cooling, it was placed in a desiccator to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare coating. Testing showed an average particle size of 510 nm, a tensile strength of 22.31 MPa, and a transmittance of over 82% across the entire light spectrum.

[0063] Figure 1 This is the infrared spectrum of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. In the system, -NCO reacts with -OH to generate urethane groups. The value at 3360 cm⁻¹ in the figure is shown. -1 and 1740cm -1 The absorption peaks at 2940 cm⁻¹ correspond to the stretching vibrations of the NH bond and C=O bond in the corresponding group, respectively. -1 and 2860cm -1 The absorption peak at 2260 cm⁻¹ is attributed to the stretching vibrations of the CH bonds in the CH₃ and CH₂ bonds of the waterborne polyurethane / acrylate hybrid coating. The antisymmetric and symmetric stretching vibrations of COC on the main molecular chain are located at 1240 cm⁻¹ and 1110 cm⁻¹, respectively. Notably, the characteristic peak of -NCO at 2260 cm⁻¹ was not observed, nor was the broad peak of -OH at high wavenumbers. These findings indicate that the -OH and -NCO reactions in the system were complete, successfully preparing the waterborne polyurethane / acrylate hybrid anti-glare coating.

[0064] Figure 2 This is a particle size distribution diagram of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. In this example, this hybrid emulsion with core-shell structured nanospheres was successfully synthesized through three steps: stepwise polymerization, seed emulsion polymerization, and free radical polymerization. As shown in the diagram, the particle size distribution ranges from 200 nm to 800 nm, with an average particle size of 510 nm. All particles meet the nanoscale requirements. Therefore, after the emulsion is formed into a coating film and then coated onto a glass plate, a rough surface at the microscopic level is formed on the glass plate, thus achieving the anti-glare requirement.

[0065] Figure 3 This is a SEM image of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. The waterborne polyurethane / acrylate hybrid emulsion prepared in this example has nanoscale particles with an average particle size of 510 nm. After the emulsion is coated onto a glass plate to form a film and dries, the original particle size and core-shell structure are still retained inside the film, forming a micro-rough surface. Figure 3 The rough structure of the coating's microscopic surface can be seen more intuitively, and each particle is spherical, proving the existence of nanospheres.

[0066] Figure 4The figure shows the stress-strain curve of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. As can be seen from the figure, the tensile strength can reach a maximum of 22.31 MPa. This is because the use of the multi-hydroxyl crosslinking agent enhances the stability of the particles in the waterborne polyurethane hybrid emulsion. The higher crosslinking density allows the particles to pack tightly in the aqueous medium, resulting in a more uniform particle arrangement and enhanced stress transfer between molecular chains, thus giving the coating excellent mechanical properties.

[0067] Figure 5 This is a transmittance image of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. The emulsion obtained in this example was uniformly coated onto a glass plate, and its transmittance was measured using a UV spectrophotometer. It is easy to see from the image that the transmittance of the coating film still exceeds 82% across the entire scanning range, indicating that the coating film has high transmittance.

[0068] Figure 6 This is a TEM image of the multi-hydroxyl crosslinked modified core-shell structured aqueous polyurethane / acrylate hybrid anti-glare resin obtained in Example 1. The difference in hydrophilicity and hydrophobicity between the diblock polymers of polyurethane and acrylate allows the molecular chains to self-assemble into latex particles with a "core-shell structure" after emulsification and free radical polymerization. As can be seen from the image, the hydrophobic acrylate acts as the "core" distributed inside the particle, while the hydrophilic polyurethane acts as the "shell," encapsulating the acrylate on the outer layer of the particle. Therefore, the analysis of the polymerization reaction principle and the results of transmission electron microscopy confirm that the core-shell structured aqueous polyurethane / acrylate hybrid emulsion has been successfully prepared.

[0069] The infrared spectrum, particle size distribution map, stress-strain diagram, transmittance diagram, and electron micrograph of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin obtained in the following examples are all consistent with... Figure 1-6 They are basically the same, so I will not provide them one by one here.

[0070] Example 2

[0071] 1) Under nitrogen protection, 3.15g of dimethylolpropionic acid, 72.5g of polytetrahydrofurandiol, 0.36g of xylitol and 45.65g of isophorone diisocyanate were placed in a constant temperature water bath and mixed evenly. 0.04g of dibutyltin diacetate was added and reacted at 63℃ for 1h, and then the temperature was raised to 83℃ and reacted for 2h to prepare a polyhydroxy crosslinked modified polyurethane prepolymer.

[0072] 2) Add 16.80g of hydroxyethyl methacrylate to the polyurethane prepolymer obtained in step 1), cool to 70℃ and react for 3.5h. During the reaction, the NCO group content in the prepolymer is determined by the di-n-butylamine method every 0.5h. Then add 4.60g of n-pentanol and react for 1h to ensure that the NCO reaction is complete and carbon-carbon double bond-terminated polyurethane prepolymer is obtained.

[0073] 3) Add 2.38g of sodium bicarbonate to the carbon-carbon double bond-terminated polyurethane prepolymer obtained in step 2) to neutralize it, cool to 40℃ and react for 1h to obtain a polyurethane prepolymer with carboxylate anions.

[0074] 4) Slowly add 558.37g of deionized water to the polyurethane prepolymer with carboxylate anions obtained in step 3), while stirring at a high speed of 2500r / min, and then cool to room temperature for 20min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0075] 5) Add 93.66g of butyl acrylate to the polyhydroxy crosslinked modified waterborne polyurethane emulsion obtained in step 4), heat to 78℃, stir evenly at a stirring rate of 250r / min, then add 0.55g of potassium persulfate and react for 7h to obtain a polyhydroxy crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare emulsion.

[0076] 6) The emulsion obtained in step 5) was uniformly coated onto a glass slide using an RDS linear coating tool. The slide was then placed in a 40°C high-temperature drying oven for 24 hours. After cooling, it was placed in a desiccator to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare coating. Testing showed an average particle size of 371 nm, a tensile strength of 17.33 MPa, and a transmittance of over 87% across the entire light spectrum.

[0077] Example 3

[0078] 1) Under nitrogen protection, 2.80g of dimethylolpropionic acid, 64.3g of polyoxypropylene glycol, 0.65g of xylitol and 40.49g of hexamethylene diisocyanate were placed in a constant temperature water bath and mixed evenly. 0.05g of organotin catalyst was added and reacted at 65℃ for 1.5h, and then the temperature was raised to 85℃ for 2h to prepare polyhydroxy crosslinked modified polyurethane prepolymer;

[0079] 2) Add 14.04g of hydroxypropyl acrylate to the polyurethane prepolymer obtained in step 1), cool to 60℃ and react for 4h. During the reaction, the NCO group content in the prepolymer is determined by the di-n-butylamine method every 1h. Then add 3.84g of isopropanol and react for 1h to ensure that the NCO reaction is complete and carbon-carbon double bond-terminated polyurethane prepolymer is obtained.

[0080] 3) Add 2.11g of sodium acetate to the carbon-carbon double bond-terminated polyurethane prepolymer obtained in step 2) to neutralize it, cool to 30℃ and react for 1h to obtain a polyurethane prepolymer with carboxylate anions.

[0081] 4) Slowly add 491.30g of deionized water to the polyurethane prepolymer with carboxylate anions obtained in step 3), while stirring at a high speed of 2000r / min, and then cool to room temperature for 20min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0082] 5) Add 82.49g of methyl 2-methacrylate to the waterborne polyurethane emulsion obtained in step 4), heat to 80℃, stir evenly at a stirring rate of 300r / min, then add 0.48g of ammonium persulfate and react for 6.5h to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare emulsion.

[0083] 6) The emulsion obtained in step 5) was uniformly coated onto a glass slide using an RDS linear coating tool. The slide was then placed in a 40°C forced-air high-temperature drying oven for 24 hours. After cooling, it was placed in a desiccator to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare coating. Testing showed an average particle size of 457 nm, a tensile strength of 18.94 MPa, and a transmittance of over 85% across the entire light spectrum.

[0084] Example 4

[0085] 1) Under nitrogen protection, 2.99g of dimethylolpropionic acid, 68.6g of polyoxypropylene triol, 1.38g of xylitol and 43.20g of lysine diisocyanate were placed in a constant temperature water bath and mixed evenly. 0.04g of organotin catalyst was added and reacted at 60℃ for 1.5h, and then the temperature was raised to 83℃ and reacted for 2.5h to prepare polyhydroxy crosslinked modified polyurethane prepolymer;

[0086] 2) Add 13.14g of hydroxypropyl methacrylate to the polyurethane prepolymer obtained in step 1), cool to 70℃ and react for 3h. During the reaction, the NCO group content in the prepolymer is determined by the di-n-butylamine method every 1h. Then add 3.59g of n-pentanol and react for 0.5h to ensure that the NCO reaction is complete and obtain a polyurethane prepolymer with carbon-carbon double bond end capping.

[0087] 3) Add 2.25g of sodium bicarbonate to the carbon-carbon double bond-terminated polyurethane prepolymer obtained in step 2) to neutralize it, cool to 40℃ and react for 0.5h to obtain a polyurethane prepolymer with carboxylate anions.

[0088] 4) Slowly add 515.79 g of deionized water to the polyurethane prepolymer with carboxylate anions obtained in step 3), while stirring at a high speed of 2600 r / min, and then cool to room temperature and react for 15 min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0089] 5) Add 86.78g of ethyl 2-methacrylate to the waterborne polyurethane emulsion obtained in step 4), heat to 76℃, stir evenly at a stirring rate of 200r / min, then add 0.50g of azobisisobutyronitrile and react for 7h to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare emulsion.

[0090] 6) The emulsion obtained in step 5) was uniformly coated onto a glass slide using an RDS linear coating tool. The slide was then placed in a 40°C forced-air high-temperature drying oven for 24 hours. After cooling, it was placed in a desiccator to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare coating. Testing showed an average particle size of 735 nm, a tensile strength of 23.23 MPa, and a transmittance of over 80% across the entire light spectrum.

[0091] Example 5

[0092] 1) Under nitrogen protection, 2.86g of dimethylolpropionic acid, 65.7g of polytetrahydrofurandiol, 1.65g of xylitol and 41.37g of isophorone diisocyanate were placed in a constant temperature water bath and mixed evenly. 0.07g of organotin catalyst was added and reacted at 60℃ for 1.5h, and then the temperature was raised to 80℃ and reacted for 2h to prepare polyhydroxy crosslinked modified polyurethane prepolymer.

[0093] 2) Add 11.70g of hydroxyethyl acrylate to the polyurethane prepolymer obtained in step 1), cool to 65℃ and react for 4h. During the reaction, the NCO group content in the prepolymer is determined by the di-n-butylamine method every 1h. Then add 3.20g of n-butanol and react for 0.5h to ensure that the NCO reaction is complete and obtain a carbon-carbon double bond-terminated polyurethane prepolymer.

[0094] 3) Add 2.16g of triethylamine to the carbon-carbon double-bond-terminated polyurethane prepolymer obtained in step 2) to neutralize it, cool to 45℃ and react for 0.5h to obtain a polyurethane prepolymer with carboxylate anions.

[0095] 4) Slowly add 489.98g of deionized water to the polyurethane prepolymer with carboxylate anions obtained in step 3), while stirring at a high speed of 2800r / min, and then cool to room temperature for 30min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion.

[0096] 5) Add 82.53g of methyl methacrylate to the waterborne polyurethane emulsion obtained in step 4), heat to 75℃, stir evenly at a stirring rate of 300r / min, then add 0.47g of azobisisobutyronitrile and react for 6.5h to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare emulsion.

[0097] 6) The emulsion obtained in step 5) was uniformly coated onto a glass slide using an RDS linear coating tool. The slide was then placed in a 40°C forced-air high-temperature drying oven for 24 hours. After cooling, it was placed in a desiccator to obtain a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare coating. Testing showed an average particle size of 816 nm, a tensile strength of 23.73 MPa, and a transmittance of over 75% across the entire light spectrum.

[0098] Table 1

[0099]

[0100] As shown in Table 1, the multi-hydroxyl crosslinked modified core-shell waterborne polyurethane / acrylate hybrid anti-glare resin prepared by xylitol in this invention exhibits excellent anti-glare performance and other comprehensive properties. The multi-hydroxyl crosslinked modified core-shell waterborne polyurethane / acrylate hybrid anti-glare coatings obtained in Examples 1-5 all exhibit excellent light transmittance across the entire scanning wavelength range (at least 75%), tensile strengths above 17 MPa, pencil hardness above H, and water absorption rates below 11.2%.

[0101] Furthermore, the reaction process of this invention does not use any organic solvents, making it green and environmentally friendly. The raw materials used are simple and readily available, and the overall process is simple and easy to operate. Although waterborne polyurethane is often used to prepare anti-glare coatings, its inherent problems, such as poor mechanical properties, poor hydrolysis resistance, and high cost, cannot be ignored. Therefore, the acrylate modification and polyhydroxy crosslinking modification used in this invention can effectively improve these defects and make the anti-glare ability even better. The hybrid emulsion obtained by this invention has nanoscale core-shell structured microspheres, which can effectively form a micro-rough surface during film formation to achieve anti-glare capability, while also ensuring high light transmittance. This allows the coating to be applied to substrate surfaces in various fields, broadening its application scenarios.

[0102] This invention prepares a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin, which can be used in any coating field, including decorative coatings, industrial coatings, and architectural coatings, with a wide range of applications. Compared with existing anti-glare waterborne polyurethanes, this invention, while possessing the basic anti-glare property, also improves upon the shortcomings of waterborne polyurethanes, such as poor mechanical properties, low hardness, poor hydrolysis resistance, high cost, and the need for large amounts of solvents in the preparation process. Simultaneously, it gives the coating good light transmittance, enabling its application on mirror surfaces such as glass, thus broadening its application areas. Furthermore, this invention prepares a nanoscale hybrid resin with a core-shell structure. The accumulation of nanoparticles constructs a micro-rough surface that meets anti-glare requirements, while also improving the low gloss and low light transmittance problems of existing waterborne polyurethane / acrylate hybrid resins.

Claims

1. A method for preparing a multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin, characterized in that... Includes the following steps: 1) Under nitrogen protection, dimethylolpropionic acid, polyether polyol, xylitol and aliphatic diisocyanate are mixed evenly, an organotin catalyst is added and reacted at 60-65℃ for 1-1.5h, and then the temperature is raised to 80-85℃ for 2-2.5h to prepare polyhydroxy crosslinked modified polyurethane prepolymer. 2) Add an unsaturated monomer containing hydroxyl groups to the polyhydroxy crosslinked modified polyurethane prepolymer, cool to 60-70℃ and react for 3-4 hours, then add an excess of a compound with hydroxyl functional groups to react completely, so as to obtain a polyurethane prepolymer with carbon-carbon double bond end capping; the compound with hydroxyl functional groups is one or more of n-pentanol, n-butanol and isopropanol. 3) Add a neutralizing agent to the obtained carbon-carbon double bond-terminated polyurethane prepolymer, and cool to 35-45℃ to react, thereby obtaining a polyurethane prepolymer with carboxylate anions. 4) Add deionized water to the obtained polyurethane prepolymer with carboxylate anions, stir at high speed, and react at room temperature for 15-30 min to obtain a multi-hydroxyl crosslinked modified waterborne polyurethane emulsion. 5) Add acrylate monomers to the obtained multi-hydroxy crosslinked modified waterborne polyurethane emulsion, heat to 75-80℃, stir evenly, add free radical initiator to react, and obtain multi-hydroxy crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin.

2. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, The raw materials, by mass percentage, are as follows: 25%–35% polyether polyol, 1%–2% dimethylolpropionic acid, 0.2%–0.8% xylitol, 15%–25% aliphatic diisocyanate, 0.03%–0.06% organotin catalyst, 5%–8% unsaturated monomers containing hydroxyl groups, 1.5%–3% compounds with hydroxyl functional groups, 0.6%–1.4% neutralizing agent, 10%–50% acrylic monomers, 0.2%–0.4% free radical initiator, and the balance being deionized water.

3. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, In step 1), the polyether polyol is one or more of polypropylene glycol, polypropylene triol, and polytetrahydrofuran glycol; the aliphatic diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, and lysine diisocyanate; and the organotin catalyst is one or more of dibutyltin diacetate, dibutyltin dilaurate, stannous octoate, and di(dodecyl sulfide)dibutyltin.

4. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, In step 2), the reaction time for adding an excess of the compound with hydroxyl functional groups is 0.5 to 1 hour; the complete NCO reaction is controlled by measuring the NCO group content in the prepolymer every 0.5 to 1 hour during the reaction process using the di-n-butylamine method.

5. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, In step 2), the unsaturated monomer containing hydroxyl groups is one or more of hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

6. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, In step 3), the reaction time for cooling to 35-45°C is 0.5-1 hour; the neutralizing agent is one or more of ammonia, potassium hydroxide, triethylamine, sodium bicarbonate, and sodium acetate.

7. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 1, characterized in that, In step 4), the stirring rate of the high-speed stirring is 2000-3000 r / min.

8. The preparation method of the multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 2, characterized in that, In step 5), the reaction time for adding the free radical initiator is 6-7 hours; the acrylic monomer is one or more of methyl methacrylate, butyl acrylate, methyl 2-methacrylate and ethyl 2-methacrylate; the free radical initiator is one or more of potassium persulfate, ammonium persulfate and azobisisobutyronitrile; the stirring speed for uniform stirring is 200-300 r / min.

9. A multi-hydroxyl crosslinked modified core-shell structure waterborne polyurethane / acrylate hybrid anti-glare resin, characterized in that... It is prepared by any one of the preparation methods described in claims 1-8.

10. The application of the multi-hydroxyl crosslinked modified core-shell structured waterborne polyurethane / acrylate hybrid anti-glare resin according to claim 9 in the preparation of anti-glare coatings.

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