An anti-oxidation LED-UV spray varnish and a preparation method thereof

Abstract

The present application relates to an anti-oxidation LED-UV spray varnish and a preparation method thereof, the anti-oxidation LED-UV spray varnish comprises polishing anti-oxidation agent 8-10 parts, 2 official polyester acrylate copolymer 30-40 parts, amino acrylate polymer 8-10 parts, TMPTA monomer 8-10 parts, HDDA monomer 3-5 parts, photoinitiator 3-8 parts and hyperbranched polyurethane acrylate 6-10 parts by weight; the polishing anti-oxidation agent comprises TPGDA monomer 30-50 parts, zinc stearate 20-30 parts, micronized polyethylene wax 20-40 parts; the particle size of the zinc stearate is 1-50 microns, and the particle size of the micronized polyethylene wax is 1-100 microns. The present application introduces hyperbranched polyurethane acrylate polymer, which can improve the curing speed of the main body and prevent cracking caused by thick coating of the paint film; the self-made polishing anti-oxidation agent can solve the problem of incomplete drying of the paint film surface caused by oxidation reaction and prevent the problem of polishing difficulty caused by excessive surface drying.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of photocuring coatings, and more particularly relates to an anti-oxygen-inhibition LED-UV spraying varnish and a preparation method thereof. BACKGROUND

[0002] The UV coatings in the prior art are mainly of the traditional mercury lamp curing type, and there are still certain problems in environmental protection, service life, energy consumption, controllability, and processing of heat-sensitive materials. With the continuous development and improvement of LED lamp bead technology, LED light source technology has made great progress, and more and more enterprises have begun to research, improve and apply LED-UV curing light source. Because LED-UV is significantly superior to traditional UV in environmental protection, service life, energy consumption, controllability and processing safety, etc.

[0003] At present, LED-UV curing technology is widely used in the field of coatings due to its energy saving, environmental protection and high efficiency. However, during the curing process of LED-UV coatings, the inhibition effect of oxygen on free radical polymerization (oxygen inhibition effect) is still a key problem. Because oxygen is easy to react with the free radicals generated by the photoinitiator to form stable peroxide radicals, which inhibits the polymerization of double bonds, resulting in incomplete curing of the coating surface, insufficient hardness, poor wear resistance and other problems, it is difficult to meet the needs of consumers in terms of polishing, hardness and scratch resistance. The existing technology usually installs a mercury lamp behind the LED lamp for secondary irradiation to solve the problem of scratch resistance of the coating film, which makes it difficult to reflect the advantages of LED-UV in low energy consumption, safety and high efficiency.

[0004] Therefore, it is of great significance to develop an LED-UV varnish with high efficient anti-oxygen inhibition performance and comprehensive physical and chemical properties. SUMMARY

[0005] The present application aims to provide an anti-oxygen-inhibition LED-UV spraying varnish and a preparation method thereof, which has good curing speed, wear resistance and film toughness.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] An anti-oxygen-inhibition LED-UV spraying varnish, by weight, comprises 8-10 parts of polishing anti-oxygen-inhibition agent, 30-40 parts of 2-off 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.

[0008] The polishing anti-oxygen inhibitor comprises TPGDA monomer 30-50 parts by weight, zinc stearate 20-30 parts by weight, and micronized polyethylene wax 20-40 parts by weight.

[0009] The micronized polyethylene wax is obtained by mechanically crushing or spraying process, and has excellent dispersibility, flowability, lubricity and surface modification capability. The melting point thereof is usually 100-140 DEG C, and the high temperature resistance is excellent. The micronized polyethylene wax is resistant to acid, alkali and solvent, and has strong stability. In the molten state, the viscosity is low, and the dispersion is easy. The friction coefficient of the material can be reduced, and the processing performance can be improved.

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

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

[0012] Preferably, the spray varnish further comprises fillers 15-20 parts; and / or, the polishing anti-oxygen inhibitor further comprises dispersants 3-10 parts.

[0013] In the technical solution, the inventors find that during the film drying process, the low particle size zinc stearate and micronized polyethylene wax powder can quickly float to the surface of the paint film, play the role of air isolation, and further reduce the influence of oxygen inhibition reaction and improve the surface drying. The long-chain alkyl group in the zinc stearate migrates to the surface of the paint film to form a lubricating film, which can reduce the direct friction between the polishing tool and the paint film surface, making the polishing smoother, and preventing local friction from causing paint film softening and adhesion.

[0014] The TPGDA monomer, i.e. tripropylene glycol diacrylate, has a CAS number of 42978-66-5, and is a bifunctional acrylate monomer. The TPGDA monomer mainly acts as a co-solvent, which is uniformly mixed with low particle size zinc stearate and micronized polyethylene under the action of dispersants to form a uniform whole and can be stably stored without delamination, precipitation, and roughening.

[0015] Preferably, the fineness of the polishing anti-oxygen inhibitor is ≤5 microns.

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

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

[0018] The MBF photoinitiator is methyl benzoylformate with 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-diphenyl phosphine oxide with CAS number 75980-60-8. The inventor found in long-term creative labor that when the TPO photoinitiator is used in combination with the MBF photoinitiator, the MBF photoinitiator quickly absorbs light energy on the surface layer to generate active radicals to start polymerization and form a preliminary curing layer to isolate the diffusion of oxygen to the bottom layer; the TPO photoinitiator absorbs long-wave ultraviolet light to broaden the wavelength range of photoinitiation and promote deep curing. The two work together to achieve gradient curing of “surface layer sealing-deep layer crosslinking” and reduce the inhibition of oxygen on the overall polymerization. Compared with adding only a single initiator, it has a more efficient drying and curing effect.

[0020] Preferably, the spray varnish further comprises 0.1-2 parts of a functional additive. The addition of the functional additive can improve the surface flatness and application performance of the coating.

[0021] Further preferably, the functional additive comprises at least one of a leveling agent, a defoaming agent, and a dispersing agent.

[0022] Specifically, the leveling agent is a polyether-modified polydimethylsiloxane or an acrylate copolymer leveling agent; the defoaming agent is a hydrophobic silica-containing polymer, 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 dispersing agent is a high-molecular polyurethane dispersing agent; and the polymerization inhibitor is a phenothiazine or a hydroquinone monomethyl ether.

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

[0024] The addition of the filler can form a physical barrier to hinder the diffusion of oxygen to the inside of the coating, increasing the filling property and mechanical strength of the varnish.

[0025] In the technical solution, the 2-functional polyester acrylate copolymer is a bifunctional polyester acrylate UV resin; the 2-functional polyester acrylate copolymer, as the main film-forming material, has a double bond structure and can participate in photocuring crosslinking reaction to provide good mechanical properties and chemical corrosion resistance. The 2-functional polyester also has good flexibility and tensile strength, can prevent cracking due to too strong curing stress when thickly coating the paint film, and has a relatively low cost, which can effectively reduce the cost of the coating.

[0026] The amino acrylate polymer has amino groups, which can form hydrogen bonds with the surface polar groups of the 2-urethane acrylate copolymer, further improving the adhesion and flexibility of the varnish.

[0027] The TMPTA monomer, i.e. trimethylolpropane triacrylate, CAS No. 15625-89-5, is a trifunctional acrylate monomer that can participate in the photocuring reaction, improving the hardness and wear resistance of the varnish.

[0028] The HDDA monomer, i.e. 1,6-hexanediol diacrylate, CAS No. 13048-33-4, is a bifunctional acrylate monomer that can adjust the curing speed and viscosity of the varnish, making it have better construction performance.

[0029] The polishing anti-oxygen inhibitor contains hindered amine groups and thiol groups. During the curing process, the peroxide radicals (ROO·) generated by the reaction of oxygen and free radicals are captured by the thiol groups (-SH) of the polishing anti-oxygen inhibitor, and a hydrogen transfer reaction occurs to generate stable sulfide (-S-) and alcohol (ROOH), while the hindered amine groups combine with the peroxide radicals to form nitroxyl radicals (NO·), inhibiting the oxygen inhibition through chain termination reaction. The dual mechanism removes the inhibitory radicals generated by oxygen during the curing process. Further improve the anti-oxygen performance of the varnish, while not affecting the polishing performance of the varnish.

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

[0031] The three-dimensional network structure of hyperbranched polyurethane acrylate and the nanoscale particles of fillers are uniformly dispersed in the coating, forming a dense crosslinked network that hinders the penetration of oxygen molecules and reduces their contact probability with free radicals.

[0032] A method for preparing the anti-oxygen LED-UV spray varnish as described above, comprising the following steps:

[0033] S1, adding 2-urethane acrylate copolymer, amino acrylate polymer, TMPTA monomer, HDDA monomer, hyperbranched polyurethane acrylate and part of the filler into the reaction kettle, stirring to form a prepolymer;

[0034] S2, continue to add photoinitiator and the remaining fillers to the reaction kettle and mix with the prepolymer;

[0035] S3, add polishing anti-oxygen inhibitor and the remaining raw materials, stir and disperse to obtain the finished product.

[0036] Further, 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, a step of filtering with a 100-200 mesh filter is further included.

[0037] Further, the preparation method of the polishing anti-oxidation inhibitor is as follows: each raw material is added to a reaction kettle, stirred uniformly, and then transferred to a grinding machine for grinding and dispersing to obtain the polishing anti-oxidation inhibitor.

[0038] Preferably, the fineness of the polished anti-oxidation inhibitor is ≤5 microns. The fineness of the polishing anti-oxidation inhibitor is detected by the scraper fineness method of GB / T1724-2019.

[0039] The beneficial effects of the present application are as follows:

[0040] (1) The present application introduces hyperbranched polyurethane acrylate polymer, which can improve the curing speed of the main body and prevent cracking caused by thick coating of the paint film; the self-made polishing anti-oxidation inhibitor solves the problem of incomplete drying of the paint film surface caused by oxidation inhibition reaction, and prevents the problem of difficult polishing caused by excessive surface drying.

[0041] (2) The present application innovatively adds a special polishing anti-oxidation inhibitor, effectively alleviates surface oxidation inhibition, and uses 2-functional polyester acrylate polymer as the skeleton, combined with amino acrylate polymer, TMPTA, HDDA and other monomers, selects MBF and TPO high-efficiency photoinitiator, matches the wavelength of LED-UV light source, improves the curing integrity, guarantees the mechanical properties and curing efficiency of the coating film, improves the polishing performance, flexibility and wear resistance, and ensures that the product meets the industrial application requirements. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purposes, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with examples.

[0043] Among them, the 2-functional polyester acrylate is purchased from Zhongshan Keta Electronic Material Co., Ltd., and the product model is 2101.

[0044] The hyperbranched polyurethane acrylate is purchased from Jiangmen Hengzhiguang New Material Co., Ltd., and the product model is 4600.

[0045] Example 1

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

[0047] Component Parts by weight Di-acrylate polyester 34 Amino acrylate polymer 8 TMPTA monomer 7 HDDA monomer 3 MBF photoinitiator 0.6 TPO photoinitiator 4.6 Hyperbranched polyurethane acrylate 6 Talc (1250 mesh) 15 Polyether modified silicone 0.4 Grind anti-oxidant 8.6 Total 87.2

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

[0049] A. Each raw material is added to a reaction kettle and stirred uniformly to obtain a premix;

[0050] B. The premix is transferred to a grinder and ground to a fineness of ≤5 microns to obtain the polishing antioxidant resistance agent.

[0051] The average particle size of the zinc stearate is 5-6 microns, and the particle size distribution D90 of the micronized polyethylene wax is 3.51 microns. After the premix is ground, the fineness is detected by the scraper fineness method of GB / T1724-2019.

[0052] The preparation method of the antioxidant resistance LED-UV spray varnish comprises the following steps:

[0053] S1. The 2-urethane acrylate copolymer, amino acrylate polymer, TMPTA monomer, HDDA monomer, hyperbranched polyurethane acrylate and part of the filler are added to a reaction kettle, stirred at a speed of 1500 rpm for 10 minutes to form a prepolymer;

[0054] S2. The photoinitiator and the remaining filler are continuously added to the reaction kettle and mixed with the prepolymer, and the stirring is continuously carried out at a speed of 1500 rpm for 15 minutes;

[0055] S3. The polishing antioxidant resistance agent and the remaining raw materials are added and stirred and dispersed at a speed of 500 rpm for 5 minutes, and then filtered with a 120-mesh filter screen, packaged, and the finished product is obtained.

[0056] Example 2

[0057] The difference between this example and Example 1 is that the antioxidant resistance LED-UV spray varnish of this example comprises the following components and weight parts:

[0058]

[0059]

[0060] The preparation steps refer to Example 1.

[0061] Example 3

[0062] The difference between this example and Example 1 is that the antioxidant resistance LED-UV spray varnish of this example comprises the following components and weight parts:

[0063] Component Parts by weight Di-acrylate polyester 40 Amino acrylate polymer 10 TMPTA monomer 10 HDDA monomer 5 MBF photoinitiator 1 TPO photoinitiator 6 Hyperbranched polyurethane acrylate 10 Nano-silica 20 Polyether modified silicone 0.4 Grind anti-oxidant 10 Total 112.4

[0064] The preparation steps refer to Example 1.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that this comparative example does not add a polishing antioxidant, and the other components, preparation steps and parameters are consistent.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Comparative Example 1 is that this comparative example replaces the hyperbranched polyurethane acrylate with a hyperbranched polyester acrylate, and the other components, preparation steps and parameters are consistent.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Comparative Example 1 is that this comparative example replaces the hyperbranched polyurethane acrylate with TMPTA, and the other components, preparation steps and parameters are consistent.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that this comparative example replaces the polishing antioxidant with a zinc stearate paste, wherein the mass percentage of zinc stearate in the zinc stearate paste is 30%, and the other components, preparation steps and parameters are consistent.

[0073] Comparative Example 5

[0074] The difference between this comparative example and Comparative Example 2 is that this comparative example also adds 8.6 parts by weight of a polyethylene wax paste, wherein the mass percentage of polyethylene in the polyethylene wax paste is 20%, and the other components, preparation steps and parameters are consistent.

[0075] Performance test scheme

[0076] The samples prepared by the examples and comparative examples were respectively coated on clean glass plates with a 50 micrometer film applicator, and after curing, the following performance tests were carried out. Among them, the curing energy is 450 mj / cm 2 , and the LED wavelength is 395 nm.

[0077] (1) Surface drying test

[0078] Reference GB / T1728-2020 finger pressure dry test. After testing, the finger mark depth is respectively represented by the numbers 0-5, wherein 0 represents no pressure mark, and the smaller the test data, the shallower the finger mark, and the better the performance.

[0079] (2) Polishing test

[0080] The test was performed according to the dry sanding method of GB / T 1770-2008. After the test, the sandpaper blocking condition was represented by the number 0-5. Among them, 0 represents no sandpaper blocking, and the larger the test data, the more serious the sandpaper blocking condition.

[0081] (3) Paint film toughness test

[0082] The test was performed according to the cupping experiment of GB / T 9753-2007. After the test, the paint film cracking condition was represented by the number 0-5. Among them, 0 represents no paint film cracking, and the larger the test data, the more serious the paint film cracking condition.

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

[0084] Table 1

[0085] Group Surface dry Grindability 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 adding zinc stearate, the polishing antioxidant (FU001) prepared by mixing micronized polyethylene wax, the surface drying and polishing of the paint film meet the expected requirements, and due to the addition of hyperbranched polyurethane acrylate, the cracking resistance of the paint film after curing is also improved.

[0087] In Comparative Examples 1-3, the hyperbranched polyurethane acrylate is better than the hyperbranched polyester acrylate and TMPTA monomer in terms of surface drying and polishing, 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 after adding zinc stearate paste (30%), the surface drying and polishing of the paint film are greatly improved under the same drying conditions, but the surface finger pressure still has slight indentation.

[0089] The test results in Comparative Example 5 show that after adding polyethylene wax paste (20%), the surface drying meets the requirements, but the sandpaper blocking still exists.

[0090] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any equivalent embodiments with equivalent changes and modifications are still within the scope of the technical solution of the present application.

Claims

1. An anti-oxidation LED-UV spray varnish, characterized in that, By weight, it includes 8-10 parts of sanding 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. By weight, the polishing antioxidant comprises 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 micrometers, and the particle size of the micronized polyethylene wax is 1-100 micrometers. The spray varnish further includes 15-20 parts of filler; and / or, the sanding antioxidant further includes 3-10 parts of dispersant; The photoinitiator includes MBF photoinitiator and TPO photoinitiator; The MBF photoinitiator is 0.5-1 parts by weight, and the TPO photoinitiator is 3-6 parts by weight. The spray varnish also includes 0.1-2 parts of functional additives.

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

3. The anti-oxidation LED-UV spray varnish according to claim 2, characterized in that, The functional additives include at least one of leveling agents, defoamers, and dispersants.

4. The anti-oxidation LED-UV spray varnish according to claim 3, characterized in that, The filler is at least one of nano-silica, transparent powder, talc, or calcium carbonate.

5. A method for preparing an antioxidant LED-UV spray varnish as described in claim 4, characterized in that, The preparation method includes the following steps: S1. Add the difunctional polyester acrylate copolymer, amino acrylate polymer, TMPTA monomer, HDDA monomer, hyperbranched polyurethane acrylate and some filler into the reactor and stir to form a prepolymer. S2. Continue to add photoinitiator and the remaining filler to the reactor and mix with the prepolymer; S3. Add the grinding antioxidant and the remaining raw materials, stir and disperse to obtain the finished product.

6. The preparation method according to claim 5, characterized in that, The preparation method of the polishing antioxidant is as follows: add each raw material into a reaction vessel, stir evenly, and then transfer it to a grinder for grinding and dispersion until the fineness is ≤5 micrometers to obtain the polishing antioxidant.

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