A yellowing-resistant, high-hardness uv film-forming clear varnish, and a preparation method and application thereof

Abstract

The application belongs to the technical field of coatings, and discloses a UV film finishing varnish with yellowing resistance and high hardness, and a preparation method and application thereof. The UV film finishing varnish comprises a hexafunctional alicyclic polyurethane acrylic resin, a difunctional linear polyurethane acrylic resin, a pure acrylic resin, an acrylic ester active diluent, a filler, an ultraviolet absorber, a non-alkaline hindered amine radical scavenger and a photoinitiator. The weight ratio of the hexafunctional alicyclic polyurethane acrylic resin, the difunctional linear polyurethane acrylic resin, the pure acrylic resin and the acrylic ester active diluent is (2.5-3.5):(1-1.5):0.5:(2.0-3.0). The preparation raw materials of the difunctional linear polyurethane acrylic resin include isocyanate, poly-1,4-butanediol and hydroxyethyl acrylate. The paint film formed by the UV film finishing varnish meets good yellowing resistance and high hardness performance, and is not prone to cracking after cold and hot cycles.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coatings, and particularly relates to a UV film finishing varnish with high hardness and anti-yellowing property, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of economy, the consumption ability of the public is continuously improved, and the consumption requirements show a continuously increasing trend. The ordinary UV coating has poor anti-yellowing property, and cannot effectively filter ultraviolet rays, so that the bottom paint film, pattern and substrate are not easy to discolor, and there is not enough hardness to prevent the paint film from being scratched by hard objects.

[0003] CN111978829A discloses a super anti-yellowing high hardness UV full bright transparent finish and a preparation method thereof. The technical solution mainly uses a mixture of bisphenol A epoxy acrylate, amine modified epoxy acrylate and acrylic ester monomer to synergistically solve the problems of poor anti-yellowing property, high brittleness and flatness of the UV paint. The technical solution is only limited to the good anti-yellowing property of the super anti-yellowing high hardness UV full bright transparent finish itself, and cannot effectively absorb ultraviolet rays, so that the bottom paint film, pattern and substrate are not easy to discolor.

[0004] CN115572521A discloses a yellowing-resistant ultraviolet light-cured coating and a preparation method thereof. The hardness of the technical solution is only 4H. The technical solution does not specify whether the paint film is white or transparent. If it is transparent, although the test data show that the yellowing-resistant ultraviolet light-cured coating itself has good anti-yellowing property, there is no sufficient data to show that the blocking effect of the nano titanium dioxide dispersion liquid used in the coating on ultraviolet rays can effectively prevent the bottom paint film, pattern or substrate from discoloring. If it is white, the pattern and texture under the paint film will be covered.

[0005] CN115160877A discloses a UV film finishing varnish and a preparation method thereof. The technical solution achieves good matte effect and excellent scratch resistance, but does not have good anti-yellowing property, and cannot prevent the bottom paint film, pattern and substrate from discoloring.

[0006] The existing varnish anti-yellowing technical solutions are mainly divided into two kinds. One is to select excellent raw materials with good anti-yellowing performance, so that the paint film only slightly yellow or even does not yellow under ultraviolet irradiation. However, the paint film has weak ultraviolet absorption, and most of the ultraviolet light will irradiate the substrate or texture, causing serious discoloration of the substrate or texture. The other is to select good raw materials with good anti-yellowing performance, and add ultraviolet absorbers and light stabilizers to absorb ultraviolet light and treat active free radicals generated by photolysis, so that the paint film only slightly yellow. This solution effectively reduces the intensity of ultraviolet light irradiating the substrate, and can better prevent the substrate from serious yellowing. However, the ultraviolet absorbers and photoinitiators have light competitive absorption, and the oxygen inhibition effect makes it difficult to form a paint film with high hardness. Moreover, ordinary ultraviolet absorbers are solid, which has low solubility and is prone to incomplete dissolution or precipitation in the paint sample. Although the existing paint film meets certain hardness and anti-yellowing performance, it is prone to cracking after cold and hot cycle.

[0007] Therefore, it is urgent to provide a paint with good anti-yellowing and high hardness, and further, the paint also has the performance of not easy to crack after cold and hot cycle. SUMMARY

[0008] The present application aims to at least solve one of the above technical problems in the prior art. To this end, the present application provides a UV coating varnish with good anti-yellowing and high hardness, and a preparation method and application thereof. The paint film formed by the UV coating varnish can simultaneously meet the performance of good anti-yellowing and high hardness, and the hardness is not less than 5H, and even can reach 6H, and is not easy to crack after cold and hot cycle.

[0009] The inventive concept of the present application: the UV film coating varnish described in the present application takes hexafunctional alicyclic polyurethane acrylic resin as the main resin, and is formulated with difunctional linear polyurethane acrylic resin, pure acrylic resin and acrylic ester active diluent in a specific ratio, that is, the performance advantages of high hardness of hexafunctional alicyclic polyurethane acrylic resin are retained, and the cracking and peeling problems of hexafunctional alicyclic polyurethane acrylic resin are solved. The preferred ultraviolet absorber and non-alkaline hindered amine radical scavenger are liquid at room temperature, have excellent compatibility with acrylic ester copolymer, the ultraviolet absorber absorbs ultraviolet rays, the ultraviolet light reaching the inner layer of the paint film is weakened, the polymerization reaction is weakened, and then the crosslinking density gradually decreases from the surface layer to the inner layer, the decrease of the crosslinking density of the inner layer weakens the shrinkage stress of the inner layer of the paint film, and the paint film has stronger adhesion to the substrate or coating layer. The synergistic effect of the yellowing-resistant acrylic ester raw material, the ultraviolet absorber and the non-alkaline hindered amine radical scavenger makes the paint film itself have excellent yellowing resistance, strong ultraviolet absorption and elimination of photolytic active radical capacity, and can protect the substrate at the bottom of the paint film from discoloration. Through the curing process of the film, the micro-creases on the surface of the paint film caused by the shrinkage of the high-functionality acrylic ester polymerization reaction can be greatly reduced, the surface of the paint film is smooth and flat, and the coating effect is excellent. The curing process of the film isolates air to avoid oxygen inhibition, the surface of the paint film is highly crosslinked, the use amount of the photoinitiator is reduced, and the influence of the initiator decomposition product on the yellowing resistance of the paint film is reduced. The smooth paint film surface, the extremely high surface crosslinking density and the high hardness alumina powder synergistically act to make the paint film have a hardness of not less than 5H, and even up to 6H, and the paint film is not easy to crack after cold and hot cycles.

[0010] The first aspect of the present application provides a yellowing-resistant and high-hardness UV film coating varnish.

[0011] Specifically, a yellowing-resistant and high-hardness UV film coating varnish comprises hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin, acrylic ester active diluent, filler, ultraviolet absorber, non-alkaline hindered amine radical scavenger and photoinitiator.

[0012] The weight ratio of the hexafunctional alicyclic polyurethane acrylic resin, the difunctional linear polyurethane acrylic resin, the pure acrylic resin and the acrylic ester active diluent is (2.5-3.5):(1-1.5):0.5:(2.0-3.0).

[0013] The preparation raw materials of the difunctional linear polyurethane acrylic resin include isocyanate, poly-1,4-butanediol and hydroxyethyl acrylate.

[0014] Preferably, the weight ratio of the hexafunctional cycloaliphatic polyurethane acrylate resin, the di-functional linear polyurethane acrylate resin, the pure acrylic resin and the acrylate reactive diluent is (2.8-3.2):(1.1-1.4):0.5:(2.2-2.8).

[0015] Preferably, the preparation method of the di-functional linear polyurethane acrylate resin comprises the following steps: mixing isocyanate, organic bismuth catalyst, poly 1,4-butanediol, reacting, then adding hydroxyethyl acrylate and polymerization inhibitor, warming, adding 6-hexanediol diacrylate when -NCO is 0, stirring to obtain the di-functional linear polyurethane acrylate resin.

[0016] Preferably, the isocyanate comprises at least one of hexamethylene diisocyanate, toluene diisocyanate, diphenyl methane diisocyanate.

[0017] Preferably, the organic bismuth catalyst comprises at least one of bismuth laurate, bismuth iso-octoate, bismuth naphthenate.

[0018] Preferably, the temperature of the reaction is 50-65℃, further preferably 55-65℃.

[0019] Preferably, the time of the reaction is 1-2 hours, further preferably 1.5-2 hours.

[0020] Preferably, the polymerization inhibitor comprises hydroquinone.

[0021] Preferably, the molecular weight of the poly 1,4-butanediol is 2000-4000, further preferably 2500-3000.

[0022] Preferably, the weight ratio of the isocyanate, poly 1,4-butanediol, hydroxyethyl acrylate is 168:(1000-1400):(110-130), further preferably 168:(1200-1300):(115-125).

[0023] Preferably, the weight ratio of the isocyanate, organic bismuth catalyst, polymerization inhibitor, 6-hexanediol diacrylate is 168:(0.5-1.2):(1-2):(300-350), further preferably 168:(0.9-1.1):(1.5-2):(320-350).

[0024] Preferably, the preparation method of the di-functional linear polyurethane acrylate resin comprises the following steps:

[0025] Put 168 kg of hexamethylene diisocyanate and 1 kg of catalyst organic bismuth into the reaction kettle, heat to 35-40℃, slowly add 1250 kg of poly 1,4-butanediol (relative molecular mass 2500), after 2 hours of reaction, heat to 65℃, when the residual -NCO is close to 50%, add 120 kg of hydroxyethyl acrylate and 1.7 kg of polymerization inhibitor hydroquinone, heat to 85℃ until the -NCO value is zero, then add 330 kg of 1,6-hexanediol diacrylate, stir until uniform and then discharge.

[0026] Preferably, the acrylate active diluent includes at least one of hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate. Hydroxyethyl methacrylate contains a hydroxyl value, which is beneficial to improve the adhesion of the paint film; 1,6-hexanediol diacrylate has low viscosity, high dilution, and good flexibility. Pentaerythritol triacrylate has fast photocuring rate and high crosslinking density; the cured film is hard and brittle, and has good resistance. Pentaerythritol triacrylate has high crosslinking density, which can further improve the hardness of the paint film, and has a hydroxyl group, which is beneficial to improve the adhesion.

[0027] The above-mentioned pure acrylic resin can be provided by Jiangxi Kailong New Materials Co., Ltd., and the model is HM-3624.

[0028] Preferably, the filler includes alumina powder. For example, the filler is alumina powder from Zhengzhou Xinli Wear-resistant Materials Co., Ltd. The alumina powder can improve the wear resistance, scratch resistance and hardness of the paint film.

[0029] Preferably, the UV film varnish further includes at least one of a dispersant, an anti-settling aid, fumed silica, and a leveling agent, and further preferably simultaneously includes a dispersant, an anti-settling aid, fumed silica, and a leveling agent.

[0030] Preferably, the ultraviolet absorber is TiNUVIN 400 from BASF. TiNUVIN 400 is a liquid, has good compatibility with acrylate substances, has strong ultraviolet absorption, and has strong protective effect on the base paint film, pattern and substrate.

[0031] Preferably, the non-basic hindered amine radical scavenger is TiNUVIN 249 from BASF. TiNUVIN 249 is a liquid, has good compatibility with acrylate substances, can quickly handle active radicals generated by photolysis of the paint film, and protects the paint film from photolysis.

[0032] Preferably, the dispersant is a modified polyester high molecular solution, such as AFCONA-4053 from Evonik.

[0033] Preferably, the defoaming agent is selected from TEGO Airex 920, an organic polymer solution. The defoaming agent does not contain silicone, does not affect the adhesion of the topcoat on the primer, has high defoaming efficiency, and also has good compatibility, without affecting the recoatability.

[0034] Preferably, the anti-settling agent is RHEOBYK-405 from BYK. RHEOBYK-405 is in liquid form, is convenient to add, can improve the efficacy of fumed silica, and effectively prevents hard settling of the powder.

[0035] Preferably, the fumed silica is CAB-0-SIL M-5 from CABOT.

[0036] Preferably, the photoinitiator is at least one of 184 (hydroxycyclohexanone phenone), 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone), TPO (2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide), and MBF (methyl benzoylformate).

[0037] Preferably, the leveling agent is an acrylic leveling agent, such as BYK-358N from BYK. The leveling agent slightly reduces the surface tension, does not affect the adhesion between the paint film layers, and also does not affect the recoatability. The acrylic leveling agent has good compatibility, without causing turbidity of the varnish.

[0038] Preferably, the preparation method of the hexafunctional alicyclic polyurethane acrylic resin comprises the following steps:

[0039] The pentaerythritol triacrylate, the organic bismuth catalyst, the polymerization inhibitor, and the isocyanate are mixed, and then the temperature is raised for reaction, to obtain the hexafunctional alicyclic polyurethane acrylic resin.

[0040] Preferably, the weight ratio of the pentaerythritol triacrylate, the organic bismuth catalyst, the polymerization inhibitor, and the isocyanate is 850:(0.1-0.5):(0.5-1.5):(200-240), and further preferably 850:(0.1-0.2):(0.5-1.5):(220-230).

[0041] Preferably, the temperature of the temperature-raising reaction is 60-85°C, and further preferably 75-85°C.

[0042] Preferably, the preparation method of the hexafunctional alicyclic polyurethane acrylic resin comprises the following steps:

[0043] Put 850 kg pentaerythritol triacrylate and 0.2 kg organic bismuth catalyst and 1 kg polymerization inhibitor hydroquinone into the reaction kettle in turn, heat to 35-40℃, slowly put in 222 kg isophorone diisocyanate, stir uniformly, then heat to 85℃, when -NCO value is zero, discharge.

[0044] Unreacted pentaerythritol triacrylate plays the role of diluting resin, reducing viscosity and improving resin hardness. The synthesis process of the six-functionality alicyclic polyurethane acrylic resin is simple in process, high in efficiency, and simple in processing, operation, control and use.

[0045] Preferably, the UV film varnish comprises the following components by weight fraction:

[0046] Six-functionality alicyclic polyurethane acrylic resin 25-35 parts;

[0047] Two-functionality linear polyurethane acrylic resin 10-15 parts;

[0048] Pure acrylic resin 5 parts;

[0049] Acrylate active diluent 20-30 parts;

[0050] Ultraviolet absorber 0.8-1.2 parts;

[0051] Non-basic hindered amine radical scavenger 0.8-1.2 parts;

[0052] Filler 20-25 parts.

[0053] Further preferably, the UV film varnish comprises the following components by weight fraction:

[0054] Six-functionality alicyclic polyurethane acrylic resin 25-35 parts;

[0055] Two-functionality linear polyurethane acrylic resin 10-15 parts;

[0056] Pure acrylic resin 5 parts;

[0057] Acrylate active diluent 20-30 parts;

[0058] Ultraviolet absorber 0.8-1.2 parts;

[0059] Non-basic hindered amine radical scavenger 0.8-1.2 parts;

[0060] Dispersant 0.5-1 part;

[0061] Defoaming agent 0.1-0.3 parts;

[0062] Filler 20-25 parts;

[0063] Anti-settling aids 0.05-0.1 parts;

[0064] Fumed silica 0.3-0.5 parts;

[0065] Photoinitiator 4-5 parts;

[0066] Leveling agent 0.2-0.4 parts.

[0067] The second aspect of the present application provides a preparation method of a yellowing-resistant, high-hardness UV film coating varnish.

[0068] Specifically, the preparation method of the yellowing-resistant, high-hardness UV film coating varnish comprises the following steps:

[0069] Mixing the components to obtain the UV film coating varnish.

[0070] Preferably, the preparation method of the UV film coating varnish comprises the following steps:

[0071] Step one: Put the hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, acrylic resin, and acrylic ester active diluent into a container (such as a dispersion cylinder), and disperse at 600-800 r / min for 5-8 min;

[0072] Step two: Slowly add the dispersant, defoaming agent, and anti-settling aids, and disperse at 600-800 r / min for 5-8 min;

[0073] Step three: Slowly add the fillers and fumed silica, adjust the rotation speed to 1300-1500 r / min, and disperse for 25-35 min;

[0074] Step four: Adjust the rotation speed to 600-800 r / min, and sequentially add the photoinitiator, the remaining acrylic ester active diluent, the ultraviolet absorber, the non-alkaline hindered amine radical scavenger, and the leveling agent, and disperse for 5-8 min to obtain the UV film coating varnish.

[0075] The third aspect of the present application provides an application of a yellowing-resistant, high-hardness UV film coating varnish.

[0076] The above-mentioned yellowing-resistant, high-hardness UV film coating varnish is applied in the field of decoration.

[0077] Preferably, the field of decoration includes wood furniture decoration and plastic decoration.

[0078] Compared with the prior art, the present application has the following beneficial effects:

[0079] (1) The UV laminating varnish described in the present application takes hexafunctional alicyclic polyurethane acrylic resin as the main resin, and is compounded with difunctional linear polyurethane acrylic resin, pure acrylic resin and acrylic ester active diluent according to a specific ratio, and the difunctional linear polyurethane acrylic resin is prepared by a specific method, so that the UV laminating varnish described in the present application can simultaneously meet good yellowing resistance and high hardness performance, the hardness is not less than 5H, and even can reach 6H, and is not prone to cracking after cold and hot cycles.

[0080] (2) The UV laminating varnish described in the present application has excellent yellowing resistance after curing, and has excellent ultraviolet absorption capacity and the ability to eliminate photolytic active free radicals, which can effectively prevent the discoloration of the underlying paint film, pattern and substrate.

[0081] While ensuring excellent yellowing resistance of the paint film and preventing discoloration of the underlying paint film, pattern and substrate, the paint film also has high hardness, effectively preventing the damage of sharp objects to the paint film. The hexafunctional alicyclic polyurethane resin has good yellowing resistance and high hardness, but has a large shrinkage rate after curing, and is prone to cracking and peeling. The present application solves the problems of cracking and peeling by the synergistic effect of the hexafunctional alicyclic polyurethane resin, the difunctional linear polyurethane acrylic resin, the pure acrylic resin and the acrylic ester active diluent with an optimal ratio, and a specific preparation method of the difunctional linear polyurethane acrylic resin, and the addition of high-hardness alumina powder, so that the hardness can be as high as 6H, and the paint film has good yellowing resistance. The use of ultraviolet absorbers and non-alkaline hindered amine free radical traps further enables the paint film to effectively protect the underlying layer from discoloration and improve adhesion. The difunctional linear polyurethane acrylic resin and 1,6-hexanediol diacrylate impart a certain toughness to the paint film, avoiding cracking and peeling of the paint film; the pure acrylic resin and hydroxyethyl methacrylate can form hydrogen bonds with the active hydroxyl groups on the surface of the substrate, enhancing the adhesion of the paint film to the underlying paint film or substrate.

[0082] (3) Using a UV cycle film press for lamination and curing solves the problem of oxygen inhibition, reduces the amount of photoinitiator used, improves the curing quality of the coating surface, reduces the micro-creases on the surface of the paint film caused by shrinkage during curing reaction, and improves the flatness of the paint film surface.

[0083] (4) High-hardness alumina powder is used, and the addition of high-hardness fillers can enhance the hardness, wear resistance and scratch resistance of the paint film, reduce the shrinkage stress of the paint film during curing reaction, and improve the adhesion. The absorption and reflection of ultraviolet rays by the paint film are enhanced, and the protective effect of the paint film on the underlying coating and substrate is enhanced. DETAILED DESCRIPTION

[0084] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0085] The raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0086] The raw materials used in the following examples and comparative examples are as follows:

[0087] The pure acrylic resin is provided by Jiangxi Kunlong New Materials Co., Ltd., and the model is HM-3624.

[0088] The filler is alumina powder, provided by Zhengzhou Xinli Wear-resistant Materials Co., Ltd.

[0089] The ultraviolet absorber is TiNUVIN 400 from BASF.

[0090] The non-basic hindered amine radical scavenger is TiNUVIN 249 from BASF.

[0091] The dispersing agent is AFCONA-4053 from Evonik.

[0092] The defoaming agent is an organic polymer solution TEGO Airex 920.

[0093] The anti-settling aid is RHEOBYK-405 from BYK-Chemie.

[0094] The fumed silica is CAB-0-SIL M-5 from CABOT.

[0095] The leveling agent is BYK-358N from BYK-Chemie.

[0096] The organic bismuth catalyst is bismuth laurate.

[0097] The photoinitiator is selected from 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone) and MBF (methyl benzoylformate).

[0098] The preparation method of the hexafunctional cycloaliphatic polyurethane acrylic resin comprises the following steps:

[0099] 850 kg of pentaerythritol triacrylate, 0.2 kg of organic bismuth catalyst and 1 kg of polymerization inhibitor hydroquinone are sequentially added to the reaction kettle, heated to 40℃, and then 222 kg of isophorone diisocyanate is slowly added. After stirring uniformly, it is heated to 85℃, and when the -NCO value is zero, it can be discharged, obtaining a hexafunctional cycloaliphatic polyurethane acrylic resin.

[0100] The preparation method of the difunctional linear polyurethane acrylic resin used in the embodiment comprises the following steps:

[0101] 168 kg of hexamethylene diisocyanate and 1 kg of organic bismuth catalyst were added to a reactor, the temperature was raised to 40°C, and 1250 kg of poly 1,4-butanediol (relative molecular weight 2500) was slowly added. After reacting for 2 hours, the temperature was raised to 65°C. When the -NCO residual content was 50%, 120 kg of hydroxyethyl acrylate and 1.7 kg of polymerization inhibitor hydroquinone were added. The temperature was raised to 85°C until the -NCO value was zero, and then 330 kg of 1,6-hexanediol diacrylate was added. The mixture was stirred evenly and discharged to obtain a difunctional linear polyurethane acrylic resin.

[0102] Example 1

[0103] A yellowing-resistant, high-hardness UV coating varnish, comprising the following components in parts by weight:

[0104] 25 parts of hexafunctional alicyclic polyurethane acrylic resin;

[0105] 10 parts of difunctional linear polyurethane acrylic resin;

[0106] 5 parts of pure acrylic resin;

[0107] 1,6-hexanediol diacrylate 17 parts

[0108] 3 parts of hydroxyethyl methacrylate

[0109] 0.8 parts of ultraviolet absorber;

[0110] 0.8 parts of non-alkaline hindered amine free radical scavenger;

[0111] 0.8 parts of dispersant;

[0112] 0.2 parts of defoaming agent;

[0113] 20 parts of alumina powder;

[0114] 0.08 parts of anti-settling agent;

[0115] 0.4 parts of fumed silica;

[0116] 1173 2 copies;

[0117] MBF 2 servings;

[0118] 0.3 parts of leveling agent.

[0119] A method for preparing a yellowing-resistant, high-hardness UV coating varnish comprises the following steps:

[0120] Step one: put the six functional cycloaliphatic polyurethane acrylic resin, di-functional linear polyurethane acrylic resin, pure acrylic resin, 1,6-hexanediol diacrylate into the dispersion cylinder in order, disperse at 700 r / min for 6 min;

[0121] Step two: slowly put in dispersant, defoaming agent and anti-settling aid, disperse at 700 r / min for 7 min;

[0122] Step three: slowly put in filler alumina powder, fumed silica, adjust the speed to 1400 r / min, disperse for 30 min;

[0123] Step four: adjust the speed to 800 r / min, sequentially put in photoinitiator, hydroxyethyl methacrylate, ultraviolet absorber, non-basic hindered amine radical scavenger and leveling agent, disperse for 8 min.

[0124] Example 2

[0125] A yellowing-resistant, high-hardness UV film coating varnish, consisting of the following components by weight:

[0126] Six functional cycloaliphatic polyurethane acrylic resin 30 parts;

[0127] Di-functional linear polyurethane acrylic resin 12 parts;

[0128] Pure acrylic resin 5 parts;

[0129] 1,6-hexanediol diacrylate 20 parts

[0130] Hydroxyethyl methacrylate 5 parts

[0131] Ultraviolet absorber 1 part;

[0132] Non-basic hindered amine radical scavenger 1 part;

[0133] Dispersant 0.8 parts;

[0134] Defoaming agent 0.2 parts;

[0135] Alumina powder 22.5 parts;

[0136] Anti-settling aid 0.08 parts;

[0137] Fumed silica 0.4 parts;

[0138] 1173 2 parts;

[0139] MBF 2.5 parts;

[0140] Leveling agent 0.3 parts.

[0141] A method for preparing a yellowing-resistant, high-hardness UV coating varnish comprises the following steps:

[0142] Step 1: Place hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin, and 1,6-hexanediol diacrylate into a dispersion tank in that order and disperse at 700 r / min for 6 minutes.

[0143] Step 2: Slowly add dispersant, defoamer and anti-settling agent, and disperse at 700r / min for 7 minutes;

[0144] Step 3: Slowly add filler alumina powder and fumed silica, adjust the speed to 1400r / min, and disperse for 30 minutes;

[0145] Step 4: Adjust the speed to 800r / min, add photoinitiator, hydroxyethyl methacrylate, ultraviolet absorber, non-alkaline hindered amine free radical scavenger and leveling agent in sequence, and disperse for 8 minutes.

[0146] Example 3

[0147] A yellowing-resistant, high-hardness UV coating varnish, comprising the following components in parts by weight:

[0148] 35 parts of hexafunctional alicyclic polyurethane acrylic resin;

[0149] 15 parts of difunctional linear polyurethane acrylic resin;

[0150] 5 parts of pure acrylic resin;

[0151] 20 parts of 1,6-hexanediol diacrylate;

[0152] 5 parts of hydroxyethyl methacrylate;

[0153] Pentaerythritol triacrylate 5 parts;

[0154] 1.2 parts of ultraviolet absorber;

[0155] 1.2 parts of non-basic hindered amine radical scavenger;

[0156] 0.8 parts of dispersant;

[0157] 0.2 parts of defoaming agent;

[0158] 25 parts of aluminum oxide powder;

[0159] 0.08 parts of anti-settling agent;

[0160] 0.4 parts of fumed silica;

[0161] 1173 2.5 copies;

[0162] MBF 2.5 parts;

[0163] Flowing agent 0.3 parts.

[0164] A preparation method of a yellowing-resistant, high-hardness UV film-forming clear varnish, comprising the following steps:

[0165] Step one: sequentially put the hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin, and 1,6-hexanediol diacrylate into a dispersion cylinder, and disperse at 700 r / min for 6 min;

[0166] Step two: slowly put in the dispersing agent, defoaming agent, and anti-settling aid, and disperse at 700 r / min for 7 min;

[0167] Step three: slowly put in the filler aluminum oxide powder and fumed silica, adjust the rotation speed to 1400 r / min, and disperse for 30 min;

[0168] Step four: adjust the rotation speed to 800 r / min, sequentially put in the photoinitiator, hydroxyethyl methacrylate, pentaerythritol triacrylate, ultraviolet absorber, non-basic hindered amine radical scavenger, and leveling agent, and disperse for 8 min.

[0169] Comparative Example 1

[0170] The only difference between this comparative example and Example 1 is that the hexafunctional alicyclic polyurethane acrylic resin of Comparative Example 1 is 15 parts by weight, and the other components and preparation process are the same as those of Example 1.

[0171] Comparative Example 2

[0172] The only difference between this comparative example and Example 1 is that the difunctional linear polyurethane acrylic resin of Comparative Example 2 is 5 parts by weight, and the other components and preparation process are the same as those of Example 1.

[0173] Comparative Example 3

[0174] The only difference between this comparative example and Example 1 is that the pure acrylic resin of Comparative Example 3 is 2 parts by weight, and the other components and preparation process are the same as those of Example 1.

[0175] Comparative Example 4

[0176] The only difference between this comparative example and Example 1 is that the 1,6-hexanediol diacrylate of Comparative Example 4 is 12 parts by weight, and the hydroxyethyl methacrylate is 0 parts by weight, and the other components and preparation process are the same as those of Example 1.

[0177] Comparative Example 5

[0178] The difference between this comparative example and Example 3 is only that the hexafunctional alicyclic polyurethane acrylate resin of Comparative Example 5 is 45 parts by weight, and the other components and the preparation process are the same as Example 3.

[0179] Comparative Example 6

[0180] The difference between this comparative example and Example 3 is only that the di-functional linear polyurethane acrylate resin of Comparative Example 6 is 22 parts by weight, and the other components and the preparation process are the same as Example 3.

[0181] Comparative Example 7

[0182] The difference between this comparative example and Example 3 is only that the pure acrylic acid resin of Comparative Example 7 is 10 parts by weight, and the other components and the preparation process are the same as Example 3.

[0183] Comparative Example 8

[0184] The difference between this comparative example and Example 3 is only that the 1,6-hexanediol diacrylate of Comparative Example 8 is 30 parts by weight, and the other components and the preparation process are the same as Example 3.

[0185] Comparative Example 9

[0186] The difference between this comparative example and Example 3 is only that the ultraviolet absorber of Comparative Example 9 is 0.4 parts by weight, and the other components and the preparation process are the same as Example 3.

[0187] Comparative Example 10

[0188] The difference between this comparative example and Example 1 is only that the aluminum oxide powder of Comparative Example 10 is 10 parts by weight, and the other components and the preparation process are the same as Example 1.

[0189] Comparative Example 11

[0190] The difference between this comparative example and Example 1 is only that the raw materials used in the preparation method of the di-functional linear polyurethane acrylate resin are different. The other components and the process are the same as Example 1.

[0191] The preparation method of the di-functional linear polyurethane acrylate resin of this comparative example is a method comprising the steps of:

[0192] Into a reaction kettle, 168 kg of hexamethylene diisocyanate and 1 kg of organic bismuth catalyst were added, and the temperature was raised to 40°C. Then, 1250 kg of poly-1,2-propylene glycol (relative molecular mass 2500) was slowly added. After 2 hours of reaction, the temperature was raised to 65°C. When the residual -NCO content was 50%, 120 kg of hydroxyethyl acrylate and 1.7 kg of polymerization inhibitor hydroquinone were added. The temperature was raised to 85°C until the -NCO value was zero. Then, 330 kg of 1,6-hexanediol diacrylate was added, and the mixture was stirred until it was homogeneous. The product was discharged, and a difunctional linear polyurethane acrylate resin was obtained.

[0193] Product effect test

[0194] The test method for the paint film formed by the UV topcoat varnish prepared in each of Examples 1-3 and Comparative Examples 1-11 is as follows:

[0195] Paint appearance: The test was performed according to the provisions in HG / T 3655-2012.

[0196] Pencil hardness: The test was performed according to the provisions in GB / T 6739-2006.

[0197] Yellowing resistance: The test was performed according to the provisions in GB / T 23983-2009.

[0198] Anti-substrate discoloration: The UV topcoat varnish was applied to a substrate with a 3D printed pattern, and cured. Then, the plates coated with the UV topcoat varnish and the plates without the UV topcoat varnish were placed outdoors for 6 months, and the color difference ΔE was tested.

[0199] Cold and hot cycle test: Three sample plates were taken, each with a size of 30 cm x 20 cm x 1 cm. A programmable constant temperature and humidity test machine was used to produce alternating changes in temperature and humidity for the samples, and the cold and hot cycle test was performed on the paint film layer formed by the UV topcoat varnish. After 5 cycles, the defects such as cracking and peeling of the paint film were described.

[0200] The performance test results of the paint film formed by the UV topcoat varnish prepared in each of Examples 1-3 and Comparative Examples 1-11 are shown in Table 1.

[0201] Table 1

[0202]

[0203]

[0204] As can be seen from the data in Table 1, the paint films of Examples 1-3 are normal, and the hardness is 5H or higher.

[0205] From the comparison of Comparative Examples 1-8 and Example 1, Example 3, it can be seen that when the weight ratio of the hexafunctional alicyclic polyurethane acrylic resin, the di-functional linear polyurethane acrylic resin, the pure acrylic resin and the acrylic ester reactive diluent is outside the range of (2.5-3.5):(1-1.5):0.5:(2.0-3.0), the paint film performance will be seriously reduced or the paint film will be abnormal.

[0206] From the comparison of Comparative Example 9 and Example 3, it can be seen that the addition of an appropriate amount of TiNUVIN 400 can efficiently absorb most of the ultraviolet rays in sunlight, effectively protecting the color of the underlying layer.

[0207] From the comparison of Comparative Example 10 and Example 1, it can be seen that an appropriate amount of aluminum oxide powder can improve the hardness of the paint film.

[0208] From the comparison of Comparative Example 11 and Example 1, it can be seen that the use of the resin obtained by polymerization of hexamethylene diisocyanate, poly 1,4-butanediol (relative molecular mass 2500) and hydroxyethyl acrylate can impart a certain toughness to the paint film, solving the problem of too brittle paint film, which is prone to cracking in cold and hot cycle tests.

Claims

1. A UV coating varnish, characterized in that: Including hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin, acrylate reactive diluent, filler, UV absorber, non-alkaline hindered amine free radical scavenger, photoinitiator; The weight ratio of the hexafunctional alicyclic polyurethane acrylic resin, the difunctional linear polyurethane acrylic resin, the pure acrylic resin and the acrylic ester reactive diluent is (2.5-3.5): (1-1.5): 0.5: (2.0-3.0); The raw materials for preparing the difunctional linear polyurethane acrylic resin include: isocyanate, poly 1,4-butanediol, and hydroxyethyl acrylate; The ultraviolet absorber and the non-alkaline hindered amine free radical scavenger are liquid at room temperature; The isocyanate is hexamethylene diisocyanate, and the relative molecular mass of the poly 1,4-butylene glycol is 2500.

2. The UV coating varnish according to claim 1, characterized in that: The preparation method of the difunctional linear polyurethane acrylic resin comprises the following steps: mixing isocyanate, an organic bismuth catalyst, and poly 1,4-butanediol, reacting, then adding hydroxyethyl acrylate and a polymerization inhibitor, heating, and when the -NCO is 0, adding 6-hexanediol diacrylate, stirring, to obtain the difunctional linear polyurethane acrylic resin.

3. The UV coating varnish according to claim 2, characterized in that: The isocyanate includes at least one of hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and / or the reaction temperature is 50-65° C., and the reaction time is 1-2 hours.

4. The UV coating varnish according to claim 2, characterized in that: The weight ratio of the isocyanate, poly 1,4-butylene glycol and hydroxyethyl acrylate is 168: (1000-1400): (110-130).

5. The UV coating varnish according to claim 2, characterized in that: The weight ratio of the isocyanate, the organic bismuth catalyst, the polymerization inhibitor, and 6-hexanediol diacrylate is 168: (0.5-1.2): (1-2): (300-350).

6. The UV coating varnish according to claim 1, characterized in that: The acrylate reactive diluent includes at least one of hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, and pentaerythritol triacrylate; and / or, the filler includes aluminum oxide powder; and / or, the UV coating varnish further includes at least one of a dispersant, an anti-settling aid, fumed silica, and a leveling agent.

7. The UV coating varnish according to claim 1, characterized in that: Calculated by weight, it includes the following components: 25-35 parts of hexafunctional alicyclic polyurethane acrylic resin; 10-15 parts of difunctional linear polyurethane acrylic resin; 5 parts of pure acrylic resin; 20-30 parts of acrylate reactive diluent; 0.8-1.2 parts of ultraviolet absorber; 0.8-1.2 parts of non-alkaline hindered amine free radical scavenger; 20-25 parts of filler.

8. The UV coating varnish according to claim 6, characterized in that: The UV coating varnish further includes a dispersant, an anti-settling agent, fumed silica and a leveling agent, and the UV coating varnish includes the following components in parts by weight: 25-35 parts of hexafunctional alicyclic polyurethane acrylic resin; 10-15 parts of difunctional linear polyurethane acrylic resin; 5 parts of pure acrylic resin; 20-30 parts of acrylate reactive diluent; 0.8-1.2 parts of ultraviolet absorber; 0.8-1.2 parts of non-alkaline hindered amine free radical scavenger; Dispersant 0.5-1 part; Defoaming agent 0.1-0.3 parts; 20-25 parts of filler; Anti-settling agent 0.05-0.1 part; 0.3-0.5 parts of fumed silica; 4-5 parts of photoinitiator; 0.2-0.4 parts of leveling agent.

9. The method for preparing the UV film-coating varnish according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components are mixed to obtain the UV film-coating varnish.

10. Use of the UV film-coating varnish according to any one of claims 1 to 8 in the field of decoration.

Images