Dispersion modified nanoparticles, preparation method thereof, hardening coating liquid and hardening coating

Abstract

The invention discloses dispersed modified nanoparticles, a preparation method thereof, a hardening coating liquid and a hardening coating. The method comprises the following steps: S1, surface ammonification modification of the nanoparticles; S2, dispersion treatment of a composite dispersant; S2-1, preparation of the composite dispersant; and S2-2, uniformly dispersing a composite dispersant in an acrylic monomer, grinding, adding the surface ammoniation modified nanoparticles prepared in the step S1, and grinding and dispersing to obtain the modified nanoparticle dispersion liquid. Through multiple synergistic effects of particle surface modification, composite dispersant preparation and dispersion process matching, stable and uniform dispersion of nanoparticles in an acrylic monomer is realized; the coating hardness strengthening agent is applied to coating hardness strengthening, so that the hardness of a coating is remarkably improved, and meanwhile, good adhesive force and other mechanical properties are kept; and the preparation method provided by the invention is simple in process, is suitable for various matrix materials and coating systems, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a dispersed modified nanoparticle, a preparation method thereof, a hardening coating solution and a hardening coating. Background Art

[0002] Coating technology is widely used in modern industry, particularly in aerospace, automotive, electronics, and other fields. Current development trends necessitate the use of impact-resistant, wear-resistant, and high-hardness coatings for protection. Coating hardness directly impacts wear resistance, impact resistance, and service life. Traditional methods for enhancing coating hardness include increasing coating thickness, using high-hardness materials, or increasing hardness through surface treatments such as nitriding and carburizing. However, these methods often result in reduced toughness and severe warping, as well as decreased bonding strength and complex processes.

[0003] In recent years, the introduction of nanotechnology has provided new insights into enhancing coating hardness. Nanoparticles, due to their unique physical and chemical properties, such as high specific surface area, quantum size effects, and surface effects, are widely used to enhance the mechanical, thermal, and electrical properties of materials. However, the stable and uniform dispersion of nanoparticles in a matrix material has always been a technical challenge.

[0004] Currently known traditional methods such as mechanical mixing and ultrasonic dispersion can often achieve an initial uniform distribution of particles, but they may still re-aggregate during long-term storage due to van der Waals forces or charge interactions between particles, failing to fundamentally solve the problem of particle agglomeration and affecting material performance. Some methods also use surfactants to adsorb on the particle surface to form electrostatic or steric barriers to prevent agglomeration, but environmental changes often affect the adsorption state, causing partial aggregation, making it difficult to achieve a monodisperse effect. Surfactants may also change the surface chemical properties of the particles, affecting the interaction between the particles and other substances, and thus affecting material performance, resulting in uneven coating performance and affecting the coating's hardness, wear resistance, and service life. Optimizing the dispersibility of nanoparticles, selecting the appropriate particle type, and controlling the dispersion process remain technical challenges that need to be addressed. Summary of the Invention

[0005] The present invention addresses the shortcomings of the prior art by providing dispersed and modified nanoparticles, a preparation method, a hardening coating solution, and a hardened coating. Through the synergistic effects of surface modification of inorganic nanoparticles, formulation of a composite dispersant, and a coordinated dispersion process, the present invention achieves stable and uniform dispersion of the nanoparticles in an acrylic monomer. This dispersion is then applied to enhance coating hardness, addressing the prior art issues of uneven and unstable nanoparticle dispersion and insufficient coating hardness.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect of the present invention, a method for preparing a modified nanoparticle dispersion is provided, comprising the following steps:

[0007] S1. Surface modification of nanoparticles by ammoniation:

[0008] The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed to obtain an inorganic nanoparticle suspension, and then an amino-containing silane coupling agent is added and stirred under heating for reaction. After the reaction is completed, the product is centrifuged and washed, and the solid product is vacuum dried to obtain surface aminated modified nanoparticles.

[0009] S2. Composite dispersant dispersion treatment:

[0010] S2-1. Preparation of composite dispersant:

[0011] Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring, ethylenediaminetetraacetic acid is added after heating, and stirring is continued to obtain a composite dispersant;

[0012] S2-2, uniformly dispersing the composite dispersant in the acrylic acid monomer, grinding, adding the surface aminated modified nanoparticles prepared in step S1, grinding and dispersing, and obtaining a modified nanoparticle dispersion.

[0013] Preferably, step S1 is specifically:

[0014] The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed for 0.5-2 hours at an ultrasonic power of 100-500W to obtain an inorganic nanoparticle suspension with a solid content of 30-50%. Then, an amino-containing silane coupling agent with a mass concentration of 0.3%-3% relative to the nanoparticles is added, and the mixture is heated at 70-90°C and stirred for at least 6 hours. After the reaction is completed, the mixture is centrifuged, washed with anhydrous ethanol, and the solid product is vacuum dried at 50-70°C for 6-24 hours to obtain surface aminated modified nanoparticles.

[0015] Preferably, the nanoparticles are at least one of silicon oxide, titanium oxide, aluminum oxide and silicon carbide, and have a diameter of 20-500 nm;

[0016] At least one of the amino-containing silane coupling agents γ-aminopropyltriethoxysilane (KH-550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH-602).

[0017] Preferably, step S2 is specifically:

[0018] S2-1. Preparation of composite dispersant:

[0019] Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring at room temperature, 0.5-2% by mass of ethylenediaminetetraacetic acid is added after heating to 60-80° C., and stirring is continued for 20-80 minutes to obtain a composite dispersant;

[0020] The mass ratio of sodium polyacrylate to sodium methacrylate sulfonate is 1:1-10:1;

[0021] S2-2, diluting the acrylic acid monomer with a solvent to a solid content of 40-60%, then adding a composite dispersant, grinding for 5-10 minutes, adding the surface ammonium-modified nanoparticles prepared in step S1, and grinding and dispersing with zirconium oxide beads to obtain a modified nanoparticle dispersion;

[0022] The added amount of the composite dispersant is 0.05%-3% of the mass of the surface ammonium modified nanoparticles, and the mass ratio of the acrylic acid monomer to the surface ammonium modified nanoparticles is 1:1-4:1.

[0023] Preferably, the zirconia beads used for grinding and dispersion have a size of 0.1-1 mm, the mass ratio of zirconia beads to modified nanoparticles is 1:1-1:5, the grinding and dispersion speed is 1000-3500 r / min, and the grinding and dispersion time is 20 min-120 min.

[0024] Preferably, the acrylic monomer is one or more of dipropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate, and the solvent is one or more of methyl isobutyl ketone, ethanol, acetone, and isopropyl alcohol.

[0025] The second aspect of the present invention provides a modified nanoparticle dispersion, which is prepared by the method described above.

[0026] A third aspect of the present invention provides a hardening coating solution comprising the following raw material components in parts by weight:

[0027] 5-30 parts of the modified nanoparticle dispersion as described above, 30-80 parts of the hardening resin, 3-6 parts of the initiator, and 50-100 parts of the organic solvent.

[0028] Preferably, the hardening resin is a polyurethane acrylate with a functionality ≥ 9;

[0029] The organic solvent is at least one of acetone, methyl isobutyl ketone, ethyl acetate, and butanone;

[0030] The photoinitiator is one or more of 1-hydroxycyclohexylphenyl ketone (initiator 184), 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone (907), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 2-hydroxy-2-methyl-1-phenyl-1-propanone (initiator 1173).

[0031] In a fourth aspect of the present invention, a hardened coating is provided, which is obtained by coating the hardened coating solution on a substrate and then subjecting the substrate to UV curing, wherein the UV curing energy is 200 mJ / cm 2 ~1000mJ / cm 2 .

[0032] The beneficial effects of the present invention are:

[0033] The present invention provides dispersed modified nanoparticles, a preparation method thereof, a hardening coating liquid and a hardening coating. The present invention achieves stable and uniform dispersion of nanoparticles in acrylic monomers through the multiple synergistic effects of surface modification of particles, formulation of a composite dispersant and matching dispersion process; the nanoparticles are applied to enhance the hardness of the coating, thereby significantly improving the hardness of the coating while maintaining good adhesion and other mechanical properties; and the preparation method provided by the invention is simple in process, broadens the application range of nanoparticles in acrylic-based materials, is applicable to a variety of substrate materials and coating systems, and has broad application prospects.

[0034] The present invention applies nanoparticle surface modification and composite dispersant technology to an acrylic monomer system. The amino groups on the surface of the aminated nanoparticles have a certain reactivity with the acrylic monomer, which improves compatibility and can enhance interfacial bonding. At the same time, it provides an action site for the composite dispersant, allowing the dispersant to tightly bind to the nanoparticles. The specifically developed composite dispersant can not only combine with the amino groups on the surface of the modified nanoparticles to exert an electrostatic repulsion effect, but also undergo a copolymerization reaction with the acrylic monomer. Under the dual action, the dispersion stability of the nanoparticles in the acrylic monomer is further improved. The multiple synergistic effects of the nanoparticle surface modification and the composite dispersant are significantly better than those of using them alone. In addition, the size of the resulting particles can be regulated by controlling the size of the zirconium oxide beads, the ratio to the ground particles, the grinding speed, and the grinding time. The present invention is applied to enhance the hardness of the coating. The nanoparticles dispersed in the acrylic monomer interact with the coating matrix, which can enhance compatibility and interfacial bonding, thereby significantly improving the hardness of the coating. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0036] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0037] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Materials and reagents used in the following examples are commercially available unless otherwise specified. In the following examples, where specific conditions are not specified, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Reagents and instruments used, where the manufacturer is not specified, are commercially available conventional products.

[0038] The present invention provides a method for preparing a modified nanoparticle dispersion, comprising the following steps:

[0039] S1. Surface modification of nanoparticles by ammoniation:

[0040] The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed to obtain an inorganic nanoparticle suspension, and then an amino-containing silane coupling agent is added and stirred under heating for reaction. After the reaction is completed, the product is centrifuged and washed, and the solid product is vacuum dried to obtain surface aminated modified nanoparticles.

[0041] Surface modification of nanoparticles by amino groups can enhance electrostatic repulsion and inhibit agglomeration. It can also synergize with composite dispersants to optimize nanoparticle dispersion, providing more stable chemical sites for binding to the dispersant. This can also improve the compatibility of nanoparticles with the coating matrix, reduce interfacial defects, and enhance interfacial bonding.

[0042] S2. Composite dispersant dispersion treatment:

[0043] S2-1. Preparation of composite dispersant:

[0044] Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring, ethylenediaminetetraacetic acid (EDTA) is added after heating, and stirring is continued to obtain a composite dispersant;

[0045] Because the amino-modified nanoparticles have a positive surface charge, the negatively charged ions of sodium polyacrylate can be firmly adsorbed on the particle surface, separating the nanoparticles through electrostatic repulsion. Simultaneously, sodium methacrylic acid sulfonate, a dispersant containing polymerizable double bonds, copolymerizes with the acrylic acid monomers in the system during the subsequent polymerization process, covalently linking the nanoparticles to the polymer network. This composite dispersant fully utilizes the rapid dispersing effect of sodium polyacrylate in the initial dispersion phase and the stable anchoring effect of sodium methacrylic acid sulfonate during the polymerization process, leveraging the synergistic effect of these two to achieve long-term stable dispersion of the nanoparticles in the matrix.

[0046] S2-2, uniformly dispersing the composite dispersant in the acrylic acid monomer, grinding, adding the surface aminated modified nanoparticles prepared in step S1, grinding and dispersing with zirconium oxide beads to obtain a modified nanoparticle dispersion.

[0047] In a preferred embodiment, step S1 is specifically as follows:

[0048] The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed for 0.5-2 hours at an ultrasonic power of 100-500W to obtain an inorganic nanoparticle suspension with a solid content of 30-50%. Then, an amino-containing silane coupling agent with a mass concentration of 0.3%-3% relative to the nanoparticles is added, and the mixture is heated at 70-90°C and stirred for reaction for at least 6 hours. After the reaction, the mixture is centrifuged and washed with anhydrous ethanol, which is repeated 2-5 times. The solid product is vacuum dried at 50-70°C for 6-24 hours to obtain surface aminated modified nanoparticles.

[0049] In a preferred embodiment, the nanoparticles are inorganic particles, such as at least one of silicon oxide, titanium oxide, aluminum oxide and silicon carbide, with a diameter of 20-500 nm. To better achieve surface modification, inorganic nanoparticles with a diameter of 20-200 nm are more preferred.

[0050] At least one of the amino-containing silane coupling agents γ-aminopropyltriethoxysilane (KH-550), N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH-602).

[0051] In a preferred embodiment, the ultrasonic power is 150-300 W, and the ultrasonic time is 0.5-1.5 h.

[0052] In a preferred embodiment, step S2 is specifically as follows:

[0053] S2-1. Preparation of composite dispersant:

[0054] Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring at room temperature, 0.5-2% by mass of ethylenediaminetetraacetic acid is added after heating to 60-80° C., and stirring is continued for 20-80 minutes to obtain a composite dispersant;

[0055] The mass ratio of sodium polyacrylate to sodium methacrylate sulfonate is 1:1-10:1; more preferably 1:1-5:1;

[0056] S2-2, diluting the acrylic acid monomer with a solvent to a solid content of 40-60%, then adding a composite dispersant, grinding for 5-10 minutes, adding the surface ammonium-modified nanoparticles prepared in step S1, and grinding and dispersing with zirconium oxide beads to obtain a modified nanoparticle dispersion;

[0057] The addition amount of the composite dispersant is 0.05%-3% of the mass of the surface ammonium modified nanoparticles, more preferably 0.05%-2%; the mass ratio of the acrylic acid monomer to the surface ammonium modified nanoparticles is 1:1-4:1.

[0058] In a preferred embodiment, the zirconia beads used for grinding and dispersion have a size of 0.1-1 mm, more preferably 0.1-0.6 mm. Too large a size will affect the particle size and dispersion uniformity of the particles after grinding.

[0059] In a preferred embodiment, the mass ratio of zirconia beads to modified nanoparticles is 1:1-1:5, more preferably 1:1.5-1:3.

[0060] The rotation speed of the grinding and dispersing is 1000-3500 r / min, more preferably 1800-2800 r / min.

[0061] The grinding and dispersion time is 20min-120min. To obtain the appropriate particle size, the grinding time is more preferably 30nin-80min. The obtained particle size is regulated by controlling the size of the zirconium oxide beads, the ratio to the ground particles, the grinding speed and the grinding time. The suspension after grinding and dispersion was analyzed by dynamic light scattering (DLS). The results showed that the particle size of the nanoparticles was stable in the range of 20-80nm, the PDI value was less than 0.2, and transmission electron microscopy (TEM) observations further confirmed that the nanoparticles had no obvious agglomeration and were in a good dispersion state. No obvious sedimentation was observed in the nanoparticle suspension after standing for 30 days, and the average particle size changed by <1%, proving its excellent dispersion stability.

[0062] In a preferred embodiment, the acrylic monomer is one or more of dipropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate, and the solvent is one or more of methyl isobutyl ketone, ethanol, acetone, and isopropyl alcohol.

[0063] The present invention also provides a modified nanoparticle dispersion, which is prepared by the above method.

[0064] The present invention also provides a hardening coating solution, comprising the following raw material components in parts by weight:

[0065] 5-30 parts of the modified nanoparticle dispersion as above, 30-80 parts of the hardening resin, 3-6 parts of the initiator, and 50-100 parts of the organic solvent.

[0066] In a preferred embodiment, the hardening resin is a polyurethane acrylate with a functionality ≥ 9;

[0067] In a preferred embodiment, the organic solvent is at least one of acetone, methyl isobutyl ketone, ethyl acetate, and butanone;

[0068] In a preferred embodiment, the photoinitiator is a cleavage-type photoinitiator, such as one or more of 1-hydroxycyclohexylphenyl ketone (Initiator 184), 2-methyl-1-(4-methylthiophenyl)-2-morpholino-1-propanone (907), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), and 2-hydroxy-2-methyl-1-phenyl-1-propanone (Initiator 1173). Cleavage-type initiators absorb energy under ultraviolet (UV) light, undergoing intramolecular cleavage to generate free radicals, thereby initiating polymerization of the monomers. These initiators are characterized by the ability to efficiently initiate polymerization reactions when used alone without the need for additional co-initiators.

[0069] A fourth aspect of the present invention provides a hardened coating layer obtained by coating the hardened coating solution described above on a substrate and then subjecting the coating to UV curing.

[0070] The hardening coating liquid is applied to the surface of the substrate and cured with appropriate energy to obtain a hardened coating with excellent performance. In a preferred embodiment, the UV curing energy is 200mJ / cm 2 ~1000mJ / cm 2 , more preferably 200 mJ / cm 2 ~600mJ / cm 2 .

[0071] In a preferred embodiment, the substrate is a PET substrate.

[0072] Through the above scheme, the modified nanoparticle dispersion provided by the present invention can achieve uniform and stable dispersion of nanoparticles in acrylic monomers, and the particle size change after 30 days is less than 1%. When applied to the coating, it can significantly improve the hardness of the coating and strengthen it to 2H / 500g.

[0073] The above is the overall concept of the present invention. Detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0074] Example 1

[0075] A method for preparing a modified nanoparticle dispersion, characterized in that it comprises the following steps:

[0076] S1. Surface modification of nanoparticles by ammoniation:

[0077] Nanoparticles (alumina nanoparticles) were added to anhydrous ethanol and ultrasonically dispersed for 30 minutes to obtain an alumina nanoparticle suspension with a solid content of 35%. A silane coupling agent γ-aminopropyltriethoxysilane (KH-550) with a mass concentration (relative to the alumina particles) of 0.5% was added to the suspension, and the mixture was stirred and reacted at 80°C for 6 hours. The mixture was centrifuged and washed with anhydrous ethanol, repeated 3 times, and vacuum dried at 55°C for 12 hours to obtain surface aminated modified nanoparticles.

[0078] Among them, the aluminum oxide nanoparticles: SS-AlO-005 (α-phase aluminum oxide, particle size 200 nm), produced by SkySpring Nanomaterials, Inc.; γ-aminopropyltriethoxysilane (KH-550), produced by Evonik.

[0079] S2. Composite dispersant dispersion treatment:

[0080] S2-1. Preparation of composite dispersant:

[0081] Dissolve 3 parts by weight of sodium polyacrylate in ethanol, slowly add 1 part of sodium methacrylate sulfonate, and slowly adjust the pH to 8 while stirring at room temperature. After heating to 70°C, add 1% by weight of the additive EDTA and continue stirring for 40 minutes to obtain a composite dispersant. The mass concentration of the composite dispersant is 2.5%.

[0082] Among them, sodium polyacrylate, Sokalan PA25 CL-FR (Sankeli PA-25), is produced by BASF; sodium methyl propylene sulfonate, MAS, is produced by Degussa, Germany.

[0083] S2-2. Preparation of modified nanoparticle dispersion:

[0084] Pentaerythritol triacrylate was diluted with methyl isobutyl ketone to a solid content of 50% and added to a grinding chamber for grinding. During the process, the above-mentioned composite dispersant was added at a mass fraction (relative to the surface ammonium-modified nanoparticles) of 1%, and the grinding and dispersion was continued for 5 minutes. Then, the surface ammonium-modified nanoparticles were added and ground, and zirconium oxide beads were used for grinding and dispersion for 60 minutes to obtain a modified nanoparticle dispersion.

[0085] The mass ratio of pentaerythritol triacrylate to the surface aminated modified nanoparticles is 2:1.

[0086] The zirconia beads used for grinding are 0.1 mm in size, the mass ratio of zirconia beads to surface ammoniation-modified nanoparticles is 1:2, and the grinding speed for grinding and dispersing the zirconia beads is 2200 r / min.

[0087] Among them, pentaerythritol triacrylate, SR444 NS, is produced by Sartomer; zirconia beads, ZR95 (0.1mm), are produced by Toray.

[0088] This embodiment also provides a hardened coating, the preparation method of which includes the following steps:

[0089] According to weight, 60 parts of hardening resin polyurethane acrylate (functionality 9) and 3 parts of initiator (184) were weighed in sequence, 60 parts of solvent methyl isobutyl ketone were added and stirred thoroughly, and then 20 parts of the above-mentioned modified nanoparticle dispersion were added and stirred thoroughly to obtain a hardening coating liquid.

[0090] The hardening coating liquid was applied on the PET substrate at an energy of 300 mJ / cm 2 The film was cured under ultraviolet light to obtain a hardened coating with a thickness of 3.0 μm.

[0091] Among them, polyurethane acrylate, 6199, is produced in Changxing; initiator (184), is produced by Coward (Wuhan Kanos Technology Co., Ltd.); methyl isobutyl ketone, is produced by Shanghai Aladdin; PET is SH92, produced by SKC of South Korea.

[0092] Example 2

[0093] Different from Example 1, the nanoparticles in this example are silicon oxide nanoparticles 904392 (particle size 200 nm), produced by Sigma-Aldrich, USA.

[0094] Example 3

[0095] Different from Example 1, the nanoparticles in this example are titanium oxide nanoparticles, RTTMIBK15WT%-N24, produced by Tokyo Chemical Industry Co., Ltd.

[0096] Example 4

[0097] Different from Example 1, the composite dispersant in this embodiment is prepared by the following method:

[0098] Dissolve 2 parts by weight of sodium polyacrylate in ethanol, slowly add 1 part of sodium methacrylate sulfonate, and slowly adjust the pH to 8 while stirring at room temperature. After heating to 70°C, add 1% by weight of the additive EDTA and continue stirring for 40 minutes to obtain a composite dispersant. The mass concentration of the composite dispersant is 2.5%.

[0099] Example 5

[0100] Different from Example 1, the composite dispersant in this embodiment is prepared by the following method:

[0101] Dissolve 1 part sodium polyacrylate in ethanol, by weight, and slowly add 1 part sodium methacrylate sulfonate. Adjust the pH to 8 while stirring at room temperature. After heating to 70°C, add 1% by weight of EDTA, an additive, and continue stirring for 40 minutes to obtain a composite dispersant. The composite dispersant has a mass concentration of 2.5%.

[0102] Example 6

[0103] Different from Example 1, in this embodiment, the method for preparing the modified nanoparticle dispersion is:

[0104] Dipentaerythritol hexaacrylate was diluted with methyl isobutyl ketone to a solid content of 50% and added to a grinding chamber for grinding. During the process, a composite dispersant with a mass fraction (relative to the surface ammonium-modified nanoparticles) of 1% was added, and the grinding and dispersion was continued for 5 minutes. Then, the surface ammonium-modified nanoparticles were added and ground, and zirconium oxide beads were used for grinding and dispersion for 60 minutes to obtain a modified nanoparticle dispersion.

[0105] The mass ratio of dipentaerythritol hexaacrylate to the surface aminated modified nanoparticles is 3:1.

[0106] The zirconia beads used for grinding were 0.1 mm in size, the mass ratio of zirconia beads to modified alumina nanoparticles was 1:2, and the grinding speed was 2100 r / min.

[0107] Among them, dipentaerythritol hexaacrylate, produced by Sartomer

[0108] Example 7

[0109] Different from Example 1, in this embodiment, the method for preparing the modified nanoparticle dispersion is:

[0110] Dipentaerythritol hexaacrylate was diluted with methyl isobutyl ketone to a solid content of 50% and added to a grinding chamber for grinding. During the process, a composite dispersant with a mass fraction (relative to the modified alumina nanoparticles) of 1% was added. The grinding and dispersion was continued for 5 minutes, and then the surface aminated modified nanoparticles were added and ground. Zirconia beads were used for grinding and dispersion for 60 minutes to obtain a modified nanoparticle dispersion.

[0111] The mass ratio of dipentaerythritol hexaacrylate to the surface aminated modified nanoparticles is 1.5:1.

[0112] The zirconia beads used for grinding were 0.1 mm in size, the mass ratio of zirconia beads to modified alumina nanoparticles was 1:1.5, and the grinding speed was 2000 r / min.

[0113] Example 8

[0114] Different from Example 1, in this embodiment, the method for preparing the hardened coating layer includes the following steps:

[0115] By weight, 50 parts of hardening resin polyurethane acrylate (functionality 9) and 4 parts of initiator (184) were weighed in sequence, 60 parts of solvent methyl isobutyl ketone were added and stirred thoroughly, and then 15 parts of the above-mentioned modified nanoparticle dispersion was added and stirred thoroughly to obtain a hardening coating liquid.

[0116] The hardening coating liquid was applied on the PET substrate at an energy of 350 mJ / cm 2 The film was cured under ultraviolet light to obtain a hardened coating with a thickness of 3.0 μm.

[0117] Example 9

[0118] Different from Example 1, in this embodiment, the method for preparing the hardened coating layer includes the following steps:

[0119] 60 parts of hardening resin polyurethane acrylate (functionality 9) and 3 parts of initiator (184) were weighed in parts by weight, 60 parts of solvent methyl isobutyl ketone were added and stirred thoroughly, and then 15 parts of the modified nanoparticle dispersion was added and stirred thoroughly to obtain a hardening coating solution.

[0120] The hardening coating liquid was applied on the PET substrate at an energy of 400 mJ / cm 2 The film was cured under ultraviolet light to obtain a hardened coating with a thickness of 3.0 μm.

[0121] Comparative Example 1

[0122] Different from Example 1, the aluminum oxide nanoparticles were not subjected to surface amination modification treatment.

[0123] Comparative Example 2

[0124] Different from Example 1, no composite dispersant is added in step S2-2 of this example.

[0125] Comparative Example 3

[0126] Different from Example 1, in step S2-2 of this example, an equal amount of sodium polyacrylate is used to replace the composite dispersant in Example 1.

[0127] Comparative Example 4

[0128] Different from Example 1, in step S2-2 of this example, an equal amount of sodium methyl propylene sulfonate is used to replace the composite dispersant in Example 1.

[0129] Comparative Example 5

[0130] Different from Example 1, the composite dispersant of this example is prepared by the following method:

[0131] Dissolve 7 parts by weight of sodium polyacrylate in ethanol, slowly add 1 part of sodium methacrylate sulfonate, and slowly adjust the pH to 8 while stirring at room temperature. After heating to 70°C, add 1% by weight of the additive EDTA and continue stirring for 40 minutes to obtain a composite dispersant. The mass concentration of the composite dispersant is 2.5%.

[0132] Comparative Example 6

[0133] Different from Example 1, in step S2-2 of this example, the size of the zirconia beads used is 1 mm.

[0134] Comparative Example 7

[0135] Different from Example 1, in step S2-2 of this example, the grinding speed during the grinding and dispersion process using zirconia beads is 1000 r / min.

[0136] Comparative Example 8

[0137] Different from Example 1, the hardened coating of this example is prepared by the following method:

[0138] 60 parts of hardening resin polyurethane acrylate (functionality 9) and 3 parts of initiator (184) were weighed in parts by weight, 60 parts of solvent methyl isobutyl ketone were added and stirred thoroughly, and then 3 parts of the modified nanoparticle dispersion uniformly dispersed in the acrylic monomer was added and stirred thoroughly to obtain a hardened coating solution.

[0139] The hardening coating liquid was applied on the PET substrate at an energy of 400 mJ / cm 2 The film was cured under ultraviolet light to obtain a hardened coating with a thickness of 3.0 μm.

[0140] Comparative Example 9

[0141] Different from Example 1, the hardened coating of this example is prepared by the following method:

[0142] 60 parts of hardening resin polyurethane acrylate (functionality 9) and 3 parts of initiator (184) were weighed in parts by weight, 60 parts of solvent methyl isobutyl ketone were added and stirred thoroughly, and then 15 parts of the modified nanoparticle dispersion uniformly dispersed in the acrylic monomer was added and stirred thoroughly to obtain a hardened coating solution.

[0143] The hardening coating liquid was applied on the PET substrate at an energy of 150 mJ / cm 2 The film was cured under ultraviolet light to obtain a hardened coating with a thickness of 3.0 μm.

[0144] In each embodiment and comparative example, the nanoparticles in the modified nanoparticle dispersion were subjected to a particle size distribution test and a stability test, and the hardened coating product was subjected to an adhesion test and a pencil hardness test.

[0145] Particle size distribution test: The milled nanoparticle suspension was diluted to 0.5 mg / mL and filtered through a 0.22 μm filter membrane. The average particle size and PDI value were measured using a dynamic light scattering instrument (Malvern Zetasizer Nano ZS) at 25°C.

[0146] Stability test: The dispersion was allowed to stand for 30 days to observe whether any sedimentation occurred. Dynamic light scattering was used to measure the initial particle size (D0) and the particle size after 30 days of standing (D1). The particle size change rate (ΔD%) was calculated as [(D1-D0) / D0]×100%.

[0147] Adhesion test: Use a grid knife to make 100 grids and stick them together with 3M600 tape to see if the coating falls off. If there is no fall off, it is recorded as 5B.

[0148] Pencil hardness: Automatic pencil hardness tester, Mitsubishi pencil.

[0149] The test results of the embodiment and comparative example are shown in Table 1 and Table 2 below:

[0150] Table 1

[0151]

[0152] Table 2

[0153]

[0154]

[0155] According to the above test results, Comparative Examples 1 and 2 show that when the nanoparticles are directly dispersed without ammoniation modification or modified without adding a composite dispersant, the nanoparticles are easily agglomerated and the bonding strength with the coating is reduced, resulting in poor adhesion;

[0156] Comparative Examples 3, 4, and 5 show that when only a single dispersant or an unreasonable ratio of components in a composite dispersant is used, the dispersion effect is significantly deteriorated, the particle size distribution is wide, and long-term stable dispersion is impossible;

[0157] Comparative Examples 6 and 7 show that the size of the zirconium oxide beads in the dispersion process is too large and the grinding speed is too low, which will lead to larger particle size, poor particle dispersion, and precipitation when placed;

[0158] Comparative Example 8 shows that when the modified dispersed particles are applied to the coating, the hardness of the coating decreases if the amount added is too small;

[0159] Comparative Example 9 shows that too low energy in the coating curing process will cause the coating adhesion to be NG and the hardness to decrease.

[0160] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing a modified nanoparticle dispersion, characterized in that: The following steps are involved: S1. Surface modification of nanoparticles by ammoniation: The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed to obtain an inorganic nanoparticle suspension, and then an amino-containing silane coupling agent is added and stirred under heating for reaction. After the reaction is completed, the product is centrifuged and washed, and the solid product is vacuum dried to obtain surface aminated modified nanoparticles. S2. Composite dispersant dispersion treatment: S2-1. Preparation of composite dispersant: Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring, ethylenediaminetetraacetic acid is added after heating, and stirring is continued to obtain a composite dispersant; S2-2, uniformly dispersing the composite dispersant in the acrylic acid monomer, grinding, adding the surface aminated modified nanoparticles prepared in step S1, grinding and dispersing, and obtaining a modified nanoparticle dispersion.

2. The method for preparing a modified nanoparticle dispersion according to claim 1, wherein Step S1 is specifically as follows: The nanoparticles are added to anhydrous ethanol and ultrasonically dispersed for 0.5-2 hours at an ultrasonic power of 100-500W to obtain an inorganic nanoparticle suspension with a solid content of 30-50%. Then, an amino-containing silane coupling agent with a mass concentration of 0.3%-3% relative to the nanoparticles is added, and the mixture is heated at 70-90°C and stirred for at least 6 hours. After the reaction is completed, the mixture is centrifuged, washed with anhydrous ethanol, and the solid product is vacuum dried at 50-70°C for 6-24 hours to obtain surface aminated modified nanoparticles.

3. The method for preparing the modified nanoparticle dispersion according to claim 2, wherein: The nanoparticles are at least one of silicon oxide, titanium oxide, aluminum oxide and silicon carbide, and have a diameter of 20-500 nm; At least one of amino-containing silane coupling agents selected from the group consisting of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

4. The method for preparing a modified nanoparticle dispersion according to claim 1, wherein: Step S2 is specifically as follows: S2-1. Preparation of composite dispersant: Sodium polyacrylate and sodium methacrylate sulfonate are mixed in ethanol, the pH is adjusted to 7-9 under stirring at room temperature, 0.5-2% by mass of ethylenediaminetetraacetic acid is added after heating to 60-80° C., and stirring is continued for 20-80 minutes to obtain a composite dispersant; The mass ratio of sodium polyacrylate to sodium methacrylate sulfonate is 1:1-10:1; S2-2, diluting the acrylic acid monomer with a solvent to a solid content of 40-60%, then adding a composite dispersant, grinding for 5-10 minutes, adding the surface ammonium-modified nanoparticles prepared in step S1, and grinding and dispersing with zirconium oxide beads to obtain a modified nanoparticle dispersion; The added amount of the composite dispersant is 0.05%-3% of the mass of the surface ammonium modified nanoparticles, and the mass ratio of the acrylic acid monomer to the surface ammonium modified nanoparticles is 1:1-4:

1.

5. The method for preparing the modified nanoparticle dispersion according to claim 4, wherein: The size of the zirconia beads used for grinding and dispersing is 0.1-1 mm, the mass ratio of the zirconia beads to the modified nanoparticles is 1:1-1:5, the rotation speed of the grinding and dispersing is 1000-3500 r / min, and the grinding and dispersing time is 20 min-120 min.

6. The method for preparing the modified nanoparticle dispersion according to claim 4, wherein: The acrylic monomer is one or more of dipropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate; and the solvent is one or more of methyl isobutyl ketone, ethanol, acetone, and isopropyl alcohol.

7. A modified nanoparticle dispersion, characterized in that: The invention can be prepared by the method according to any one of claims 1 to 6.

8. A hardening coating liquid, characterized in that: It includes the following raw material components by weight: 5-30 parts of the modified nanoparticle dispersion according to claim 7, 30-80 parts of a hardening resin, 3-6 parts of an initiator, and 50-100 parts of an organic solvent.

9. The hardening coating liquid according to claim 8, characterized in that The hardening resin is a polyurethane acrylate with a functionality ≥ 9; The organic solvent is at least one of acetone, methyl isobutyl ketone, ethyl acetate, and butanone; The photoinitiator is one or more of 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

10. A hardened coating, characterized in that: The hardening coating liquid according to claim 8 or 9 is coated on a substrate and then cured by UV, wherein the UV curing energy is 200 mJ / cm 2 ~1000mJ / cm 2 .

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