Anti-oxygen-resistance LED-UV spraying varnish and preparation method thereof

Abstract

The invention relates to an anti-oxygen-resistance LED-UV spraying varnish and a preparation method thereof.The anti-oxygen-resistance LED-UV spraying varnish is prepared from, by weight, 8-10 parts of a polishing anti-oxygen-resistance agent, 30-40 parts of a bifunctional polyester acrylate copolymer, 8-10 parts of an amino acrylate polymer, 8-10 parts of a TMPTA monomer, 3-5 parts of an HDDA monomer, 3-8 parts of a photoinitiator and 6-10 parts of hyperbranched polyurethane acrylate; the polishing antioxidant is prepared from 30 to 50 parts of TPGDA monomer, 20 to 30 parts of zinc stearate and 20 to 40 parts of micronized polyethylene wax; the particle size of the zinc stearate is 1-50 microns, and the particle size of the micronized polyethylene wax is 1-100 microns. By introducing the hyperbranched polyurethane acrylic polymer, the curing speed of a main body is increased, and later cracking caused by thick coating of a paint film is prevented; and a self-made polishing anti-oxidation inhibitor is matched to solve the problem that the surface of a paint film is not completely dried due to an oxygen inhibition reaction, and the problem that polishing is difficult due to excessive drying of the surface is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of light-curing coatings, and more particularly relates to an anti-oxidation and resistance LED-UV spray varnish and a preparation method thereof. Background Art

[0002] Existing UV coatings are still primarily based on traditional mercury lamp curing, which presents challenges in environmental performance, lifespan, energy consumption, controllability, and processing of heat-sensitive materials. With the continuous development and improvement of LED lamp technology, LED light source technology has made significant progress, and an increasing number of companies are beginning to research, improve, and apply LED-UV curing light sources, as LED-UV is significantly superior to traditional UV in terms of environmental performance, lifespan, energy consumption, controllability, and processing safety.

[0003] Currently on the market, LED-UV curing technology is widely used in the field of coatings due to its advantages such as energy saving, environmental protection, and high efficiency. However, during the curing process of LED-UV coatings, the inhibition of free radical polymerization by the presence of oxygen (oxygen inhibition effect) remains a key problem. Since oxygen easily reacts with photoinitiators to produce free radicals, forming stable peroxy radicals, it inhibits double bond polymerization, leading to problems such as incomplete curing of the coating surface, insufficient hardness, and poor wear resistance. It is difficult to meet consumer demand in terms of polishing, hardness, and scratch resistance. Existing technologies usually install a mercury lamp behind the LED lamp for secondary irradiation to solve the problem of scratch resistance on the coating surface. This makes it difficult to reflect the advantages of LED-UV in terms of low energy consumption, safety, and high efficiency.

[0004] Therefore, it is of great significance to develop an LED-UV varnish with both high-efficiency anti-oxidation barrier properties and comprehensive physical and chemical properties. Summary of the Invention

[0005] The object of the present invention is to provide an antioxidant LED-UV spray varnish and a preparation method thereof, which has the characteristics of good curing speed, wear resistance and paint film toughness.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] An antioxidant LED-UV spray varnish, comprising, by weight, 8-10 parts of a polishing antioxidant, 30-40 parts of a difunctional polyester acrylate copolymer, 8-10 parts of an aminoacrylate polymer, 8-10 parts of a TMPTA monomer, 3-5 parts of a HDDA monomer, 3-8 parts of a photoinitiator, and 6-10 parts of a hyperbranched polyurethane acrylate;

[0008] In parts by weight, the polishing antioxidant includes 30-50 parts of TPGDA monomer, 20-30 parts of zinc stearate, and 20-40 parts of micronized polyethylene wax; the particle size of the zinc stearate is 1-50 microns, and the particle size of the micronized polyethylene wax is 1-100 microns.

[0009] Micronized polyethylene wax is obtained by mechanically crushing or spraying polyethylene wax (PE wax) into a micronized powder. It has excellent dispersibility, fluidity, lubricity, and surface modification capabilities. Its melting point is typically 100-140°C, with excellent high-temperature resistance. It is also resistant to acids, alkalis, and solvents, and has high stability. In its molten state, it has low viscosity and is easy to disperse. It can reduce the material's coefficient of friction and improve processing performance.

[0010] Furthermore, the particle size of the micronized polyethylene wax is 1-10 microns.

[0011] More preferably, the particle size of the zinc stearate is 1-10 microns.

[0012] Preferably, the spray varnish further comprises 15-20 parts of filler; and / or the polishing antioxidant further comprises 3-10 parts of dispersant.

[0013] In this technical solution, the inventors discovered through long-term creative work that during the film-making and drying process, low-particle zinc stearate and micronized polyethylene wax powder can quickly float to the surface of the paint film, playing a role in isolating the air, thereby reducing the impact of the oxygen barrier reaction and improving surface drying. The long-chain alkyl groups in the zinc stearate can form a lubricating film after migrating to the surface of the paint film. This film can reduce the direct friction between the polishing tool and the paint film surface, making the polishing smoother, while preventing the high temperature of local friction from causing the paint film to soften and adhere.

[0014] Among them, TPGDA monomer, tripropylene glycol diacrylate (CAS No. 42978-66-5), is a difunctional acrylate monomer. It primarily serves as a cosolvent. With the help of a dispersant, TPGDA monomer, after grinding, is uniformly mixed with the low-particle zinc stearate and micronized polyethylene powders into a homogeneous whole that can be stored stably without delamination, precipitation, or coarsening.

[0015] Preferably, the fineness of the polished antioxidant is ≤5 microns.

[0016] Preferably, the photoinitiator includes MBF photoinitiator and TPO photoinitiator.

[0017] Further preferably, the weight portion of the MBF photoinitiator is 0.5-1 parts, and the weight portion of the TPO photoinitiator is 3-6 parts.

[0018] MBF photoinitiator is methyl benzoylformate, CAS number 15206-55-0, which can generate active free radicals to initiate the curing reaction of monomers and polymers and improve the curing efficiency.

[0019] The TPO photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (CAS number 75980-60-8). Through long-term creative work, the inventors discovered that when TPO and MBF are used together, the MBF rapidly absorbs light energy at the surface layer, generating active free radicals to initiate polymerization and form a preliminary cured layer, isolating oxygen from diffusing to the underlying layers. The TPO photoinitiator absorbs long-wave UV light, broadening the wavelength range for photoinitiation and promoting deeper curing. The two work synergistically to achieve a gradient curing process from "surface sealing to deep crosslinking," reducing oxygen inhibition on overall polymerization. This results in a more efficient drying and curing effect than using only one initiator alone.

[0020] Preferably, the spray varnish further comprises 0.1-2 parts of a functional additive, which can improve the surface smoothness and construction performance of the coating.

[0021] More preferably, the functional additive includes at least one of a leveling agent, a defoaming agent, and a dispersant.

[0022] Specifically, the leveling agent is a polyether-modified polydimethylsiloxane or an acrylate copolymer leveling agent; the defoaming agent is a polymer containing hydrophobic silica, a mineral oil-based defoaming agent or a polyether-modified siloxane; the adhesion promoter is a phosphate monomer or a silane coupling agent; the light stabilizer is a benzotriazole ultraviolet absorber or a hindered amine light stabilizer; the dispersant is a polymer polyurethane dispersant; and the polymerization inhibitor is phenothiazine or hydroquinone monomethyl ether.

[0023] Preferably, the filler is at least one of nano-silicon dioxide, transparent powder, talc or calcium carbonate.

[0024] The addition of fillers can form a physical barrier, hindering the diffusion of oxygen into the coating, and increasing the filling capacity and mechanical strength of the varnish.

[0025] In this technical solution, a difunctional polyester acrylate copolymer, also known as a difunctional polyester acrylate UV resin, serves as the primary film-forming substance. This difunctional polyester acrylate copolymer possesses a double bond structure that participates in a photocuring crosslinking reaction, providing excellent mechanical properties and chemical resistance. The difunctional polyester also possesses excellent flexibility and tensile strength, preventing cracking caused by excessive curing stress during thick coatings. Its low cost effectively reduces coating costs.

[0026] The amino acrylate polymer has an amino group that can form hydrogen bonds with the polar groups on the surface of the difunctional polyester acrylate copolymer, further improving the adhesion and flexibility of the varnish.

[0027] TMPTA monomer, trimethylolpropane triacrylate, CAS number 15625-89-5, is a trifunctional acrylate monomer that can participate in the photocuring reaction to improve the hardness and wear resistance of the varnish.

[0028] HDDA monomer, namely 1,6-hexanediol diacrylate, CAS number 13048-33-4, is a difunctional acrylate monomer that can adjust the curing speed and viscosity of varnish, giving it better construction performance.

[0029] Polishing antioxidants contain hindered amine and thiol groups. During the curing process, peroxyl radicals (ROO·) generated by the reaction of oxygen with free radicals are captured by the thiol groups (-SH) of the polishing antioxidant, resulting in a hydrogen transfer reaction to form stable sulfides (-S-) and alcohols (ROOH). Simultaneously, the hindered amine groups combine with the peroxyl radicals to form nitroxide radicals (NO·), which inhibit oxygen inhibition through chain termination. This dual mechanism removes the inhibitory free radicals generated by oxygen during the curing process, further improving the varnish's antioxidant properties while maintaining its polishability.

[0030] Hyperbranched polyurethane acrylate (HBPUA) is a functional photocurable resin that combines the three-dimensional structure of a hyperbranched polymer (HBP) with the performance advantages of polyurethane acrylate (PUA). The intramolecular cavities of HPUA can capture oxygen molecules, reducing oxygen inhibition and providing excellent oxygen barrier properties, preventing oxidative degradation of the varnish during use.

[0031] The three-dimensional network structure of hyperbranched polyurethane acrylate and the nano-scale particles of the filler are evenly dispersed in the coating to form a dense cross-linked network, which hinders the penetration of oxygen molecules and reduces the probability of their contact with free radicals.

[0032] A method for preparing the above-mentioned antioxidant LED-UV spray varnish comprises the following steps:

[0033] S1, adding a difunctional polyester acrylate copolymer, an amino acrylate polymer, a TMPTA monomer, a HDDA monomer, a hyperbranched polyurethane acrylate and a portion of filler into a reactor, and stirring to form a prepolymer;

[0034] S2. Continue adding photoinitiator and remaining filler into the reactor and mix with the prepolymer;

[0035] S3. Add polishing antioxidant and remaining raw materials, stir and disperse to obtain the finished product.

[0036] Furthermore, in step S1, the stirring speed is 1200-1800 rpm, and the stirring time is 5-15 minutes; in step S2, the stirring speed is 1200-1800 rpm, and the stirring time is 10-20 minutes; in step S3, the stirring speed is 200-800 rpm, and the stirring time is 3-10 minutes; after stirring and dispersing, the step of filtering with a 100-200 mesh filter is also included.

[0037] Furthermore, the preparation method of the polishing antioxidant is as follows: adding the raw materials into a reactor, stirring evenly, and then transferring them to a grinder for grinding and dispersion to obtain the polishing antioxidant.

[0038] Preferably, the fineness of the polished antioxidant after grinding is ≤5 microns. The fineness of the polished antioxidant is tested with reference to the scraper fineness method of GB / T1724-2019.

[0039] Beneficial effects of the present invention:

[0040] (1) The present invention improves the curing speed of the main body while preventing the late cracking caused by thick coating of the paint film by introducing a hyperbranched polyurethane acrylic polymer; it is combined with a homemade polishing antioxidant to solve the problem of incomplete drying of the paint film surface due to oxygen inhibition reaction, and prevent the problem of difficulty in polishing caused by excessive surface drying.

[0041] (2) The present invention innovatively adds a special polishing antioxidant to effectively alleviate surface oxygen inhibition, and uses a bifunctional polyester acrylic polymer as the skeleton, combined with amino acrylate polymers, TMPTA, HDDA and other monomers, selects MBF and TPO high-efficiency photoinitiators, matches the wavelength of LED-UV light source, improves curing integrity, ensures the mechanical properties and curing efficiency of the coating, improves polishing performance, flexibility and wear resistance, and ensures that the product meets industrial application requirements. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0043] Among them, the difunctional polyester acrylate was purchased from Zhongshan Ketian Electronic Materials Co., Ltd. with the product brand number 2101.

[0044] Hyperbranched polyurethane acrylate was purchased from Jiangmen Hengzhiguang Environmental Protection New Materials Co., Ltd. with the product brand 4600.

[0045] Example 1

[0046] An anti-oxidation and anti-UV LED-UV spray varnish, comprising the following components in parts by weight:

[0047] Components parts by weight 2-functional polyester acrylate 34 Aminoacrylate polymer 8 TMPTA monomer 7 HDDA monomer 3 MBF photoinitiator 0.6 TPO photoinitiator 4.6 Hyperbranched polyurethane acrylate 6 Talc powder (1250 mesh) 15 Polyether modified silicone 0.4 Polishing antioxidant 8.6 total 87.2

[0048] The preparation of the polishing antioxidant includes the following components and weight parts: 40 parts of TPGDA monomer, 5 parts of dispersant, 25 parts of zinc stearate, and 30 parts of micronized polyethylene wax. The preparation method includes the following steps:

[0049] A. Add all raw materials into the reactor and stir evenly to obtain a premix;

[0050] B. Transfer the premix to a grinder and grind to a fineness of ≤5 microns to obtain the polished antioxidant.

[0051] The average particle size of zinc stearate is 5-6 μm, and the particle size distribution D90 of micronized polyethylene wax is 3.51 μm. After grinding, the premix is tested for fineness using the scraper fineness method according to GB / T1724-2019.

[0052] The method for preparing the above-mentioned antioxidant LED-UV spray varnish comprises the following steps:

[0053] S1, adding a difunctional polyester acrylate copolymer, an amino acrylate polymer, a TMPTA monomer, a HDDA monomer, a hyperbranched polyurethane acrylate, and a portion of the filler into a reactor, and stirring at a speed of 1500 rpm for 10 minutes to form a prepolymer;

[0054] S2. Add the photoinitiator and the remaining filler to the reactor, mix with the prepolymer, and continue stirring at 1500 rpm for 15 minutes;

[0055] S3. Add the polishing antioxidant and the remaining raw materials, stir and disperse at a speed of 500 rpm for 5 minutes, then filter with a 120-mesh filter, and package to obtain the finished product.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that the anti-oxidation LED-UV spray varnish of this embodiment includes the following components and parts by weight:

[0058]

[0059]

[0060] The preparation steps are as shown in Example 1.

[0061] Example 3

[0062] The difference between this embodiment and embodiment 1 is that the anti-oxidation LED-UV spray varnish of this embodiment includes the following components and parts by weight:

[0063] Components parts by weight 2-functional polyester acrylate 40 Aminoacrylate polymer 10 TMPTA monomer 10 HDDA monomer 5 MBF photoinitiator 1 TPO photoinitiator 6 Hyperbranched polyurethane acrylate 10 Nanosilica 20 Polyether modified silicone 0.4 Polishing antioxidant 10 total 112.4

[0064] The preparation steps are as shown in Example 1.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that no polishing antioxidant is added in this comparative example, and the other components, preparation steps and parameters are the same.

[0067] Comparative Example 2

[0068] The difference between this comparative example and comparative example 1 is that in this comparative example, hyperbranched polyurethane acrylate is replaced by hyperbranched polyester acrylate, and the remaining components, preparation steps and parameters are the same.

[0069] Comparative Example 3

[0070] The difference between this comparative example and comparative example 1 is that in this comparative example, hyperbranched polyurethane acrylate is replaced by TMPTA, and the other components, preparation steps and parameters are the same.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that in this comparative example, the polishing antioxidant is replaced by zinc stearate slurry, wherein the mass percentage of zinc stearate in the zinc stearate slurry is 30%, and the other components, preparation steps and parameters are the same.

[0073] Comparative Example 5

[0074] The difference between this comparative example and comparative example 2 is that this comparative example further adds 8.6 parts by weight of polyethylene wax slurry, wherein the mass percentage of polyethylene in the polyethylene wax slurry is 20%, and the remaining components, preparation steps and parameters are the same.

[0075] Performance testing plan

[0076] The samples prepared in the examples and comparative examples were respectively coated on clean glass plates using a 50 micron film applicator, and the following performance tests were performed after curing. 2 , the LED wavelength is 395nm.

[0077] (1) Surface drying test

[0078] Refer to the finger pressure dryness test of GB / T1728-2020. After the test, the depth of the finger pressure mark is represented by numbers 0-5, where 0 means no indentation. The smaller the test value, the shallower the finger pressure mark and the better the performance.

[0079] (2) Polishability test

[0080] The dry sanding method according to GB / T1770-2008 was used for testing. After the test, the sandpaper blockage was indicated by numbers 0-5. 0 indicates no sandpaper blockage, and larger numbers indicate more severe sandpaper blockage.

[0081] (3) Paint film toughness test

[0082] The test was conducted with reference to the cupping test in GB / T9753-2007. After the test, the cracking of the paint film was indicated by numbers 0-5. The number 0 indicates no cracking of the paint film, and the larger the test number, the more severe the cracking of the paint film.

[0083] The test results are shown in Table 1.

[0084] Table 1

[0085] Group Surface dryness Polishability Paint film toughness Example 1 0 0 0 Example 2 0 0 0 Example 3 0 0 0 Comparative Example 1 2 2 1 Comparative Example 2 3 3 4 Comparative Example 3 4 4 3 Comparative Example 4 1 1 1 Comparative Example 5 0 2 1

[0086] From the test results in Table 1, it can be seen that after zinc stearate and micronized polyethylene wax were added to form a polishing antioxidant (FUOO1) in the embodiment, the surface drying and polishing properties of the paint film met the expected requirements, and the addition of hyperbranched polyurethane acrylate also improved the crack resistance of the paint film after curing.

[0087] In Comparative Examples 1-3, the hyperbranched polyurethane acrylate is superior to the hyperbranched polyester acrylate and TMPTA monomer in surface drying and polishing properties, and due to the presence of -NH2-CO-, the hyperbranched polyurethane acrylate exhibits better paint film toughness and wear resistance.

[0088] The test results in Comparative Example 4 show that under the same drying conditions, the surface drying and polishing properties of the paint film are greatly improved after adding zinc stearate slurry (30%), but there are still slight indentations on the surface when pressed by fingers.

[0089] The test results in Comparative Example 5 show that after adding polyethylene wax slurry (20%), the surface drying meets the requirements, but the sandpaper is still clogged during polishing.

[0090] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An anti-oxidation LED-UV spray varnish, characterized in that: By weight, it includes 8-10 parts of polishing antioxidant, 30-40 parts of difunctional polyester acrylate copolymer, 8-10 parts of amino acrylate polymer, 8-10 parts of TMPTA monomer, 3-5 parts of HDDA monomer, 3-8 parts of photoinitiator and 6-10 parts of hyperbranched polyurethane acrylate; In parts by weight, the polishing antioxidant includes 30-50 parts of TPGDA monomer, 20-30 parts of zinc stearate, and 20-40 parts of micronized polyethylene wax; the particle size of the zinc stearate is 1-50 microns, and the particle size of the micronized polyethylene wax is 1-100 microns.

2. The anti-oxidation LED-UV spray varnish according to claim 1, characterized in that: The spray varnish further comprises 15-20 parts of filler; and / or the polishing antioxidant further comprises 3-10 parts of dispersant.

3. The anti-oxidation LED-UV spray varnish according to claim 1, characterized in that: The fineness of the polishing antioxidant is ≤5 microns.

4. The anti-oxidation LED-UV spray varnish according to claim 1, characterized in that: The photoinitiator includes MBF photoinitiator and TPO photoinitiator.

5. The anti-oxidation LED-UV spray varnish according to claim 4, characterized in that: The weight portion of the MBF photoinitiator is 0.5-1 parts, and the weight portion of the TPO photoinitiator is 3-6 parts.

6. The anti-oxidation LED-UV spray varnish according to claim 1, characterized in that: The spray varnish further comprises 0.1-2 parts of functional additives.

7. The anti-oxidation LED-UV spray varnish according to claim 6, characterized in that: The functional additive includes at least one of a leveling agent, a defoaming agent, and a dispersant.

8. The anti-oxidation LED-UV spray varnish according to claim 2, characterized in that: The filler is at least one of nano silicon dioxide, transparent powder, talcum powder or calcium carbonate.

9. A method for preparing the antioxidant LED-UV spray varnish according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1, adding a difunctional polyester acrylate copolymer, an amino acrylate polymer, a TMPTA monomer, a HDDA monomer, a hyperbranched polyurethane acrylate and a portion of filler into a reactor, and stirring to form a prepolymer; S2. Continue adding photoinitiator and remaining filler into the reactor and mix with the prepolymer; S3. Add polishing antioxidant and remaining raw materials, stir and disperse to obtain the finished product.

10. The preparation method according to claim 9, characterized in that The preparation method of the polished antioxidant is as follows: adding various raw materials into a reaction kettle, stirring evenly, and then transferring to a grinder for grinding and dispersion until the fineness is ≤5 microns to obtain the polished antioxidant.

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