Yellowing-resistant and high-hardness UV (ultraviolet) laminating varnish as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and discloses an anti-yellowing and high-hardness UV (ultraviolet) laminating varnish as well as a preparation method and application thereof. The UV film coating varnish comprises six-functionality alicyclic polyurethane acrylic resin, two-functionality linear polyurethane acrylic resin, pure acrylic resin, an acrylate reactive diluent, a filler, an ultraviolet light absorber, a non-alkaline hindered amine free radical scavenger and a photoinitiator. The weight ratio of the six-functionality alicyclic polyurethane acrylic resin to the two-functionality linear polyurethane acrylic resin to the pure acrylic resin to the acrylate reactive diluent is (2.5-3.5): (1-1.5): 0.5: (2.0-3.0); the bifunctional linear polyurethane acrylic resin is prepared from the following raw materials: isocyanate, poly (1, 4-butanediol) and hydroxyethyl acrylate. A paint film formed by the UV film-coated varnish has good yellowing resistance and high hardness, and is not easy to crack after thermal cycling.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a yellowing-resistant, high-hardness UV coating varnish and a preparation method and application thereof. Background Art

[0002] With the rapid development of the economy, the public's consumption capacity continues to improve, and consumption requirements are showing a trend of continuous improvement. Ordinary UV coatings have poor yellowing resistance and cannot effectively filter ultraviolet rays, making the underlying paint film, pattern and substrate less likely to change color. They also do not have enough hardness to prevent hard objects from scratching the paint film.

[0003] CN111978829A discloses a super yellowing-resistant high-hardness UV full-bright transparent topcoat and its preparation method. The technical solution mainly adopts the synergistic effect of bisphenol A epoxy acrylate, amino-modified epoxy acrylate and acrylate monomer mixture to solve the problems of poor yellowing resistance, large brittleness and flatness of UV paint. The technical solution is limited to the good yellowing resistance of the super yellowing-resistant high-hardness UV full-bright transparent topcoat itself, and cannot effectively absorb ultraviolet rays, and cannot make the bottom paint film, pattern and substrate less prone to discoloration.

[0004] CN115572521A discloses a yellowing-resistant UV-curing coating and a preparation method thereof. The hardness of this technical solution only reaches 4H. This technical solution does not specify whether the paint film is white or transparent. If it is transparent, although the test data shows that the yellowing-resistant UV-curing coating itself has good yellowing resistance, there is no sufficient data to show that the ultraviolet light blocking effect of the nano-titanium dioxide dispersion used in the coating can effectively prevent the underlying paint film, pattern or substrate from changing color; if it is white, it will cover the pattern and texture under the paint film.

[0005] CN115160877A discloses a UV coating topcoat and a preparation method thereof. This technical solution achieves a good matte effect and excellent scratch resistance, but does not have good yellowing resistance and cannot prevent the underlying paint film, pattern and substrate from changing color.

[0006] There are two main technical solutions for the yellowing resistance of varnish. One is to select raw materials with excellent yellowing resistance so that the paint film only slightly yellows or even does not yellow under ultraviolet irradiation. However, the paint film of this solution has weak absorption of ultraviolet rays, and most of the ultraviolet rays will irradiate the substrate or texture, causing serious discoloration of the substrate or texture. The other is to select raw materials with good yellowing resistance, add ultraviolet absorbers and light stabilizers, absorb ultraviolet rays and treat active free radicals of photolysis, so that the paint film only slightly yellows. This solution effectively reduces the intensity of ultraviolet rays irradiating the substrate, which can better prevent the substrate from yellowing more seriously. However, there is a situation of light competition absorption between the ultraviolet absorber and the photoinitiator, and the effect of oxygen inhibition makes it difficult to form a paint film with high hardness. Moreover, ordinary ultraviolet absorbers are solids with low solubility, and are prone to problems of not being completely dissolved or precipitating in the paint sample. Although the existing paint film meets certain hardness and yellowing resistance, it is easy to crack after hot and cold cycles.

[0007] Therefore, there is an urgent need to provide a paint that has both good yellowing resistance and high hardness. Furthermore, the paint also has the properties of being resistant to cold and hot cycles and not prone to cracking. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a yellowing-resistant, high-hardness UV coating varnish and its preparation method and application. The paint film formed by the UV coating varnish can simultaneously meet the requirements of good yellowing resistance and high hardness performance, with a hardness of not less than 5H, and even up to 6H, and is not easy to crack after cold and hot cycles.

[0009] The inventive concept of the present invention: The UV coating varnish of the present invention uses hexafunctional alicyclic polyurethane acrylic resin as the main resin, and is matched with difunctional linear polyurethane acrylic resin, pure acrylic resin and acrylic ester reactive diluent in a specific ratio, which not only retains the performance advantage of high hardness of hexafunctional alicyclic polyurethane acrylic resin, but also solves the cracking and peeling problems of hexafunctional alicyclic polyurethane acrylic resin. The preferred ultraviolet absorber and non-alkaline hindered amine free radical scavenger are liquid at room temperature and have excellent compatibility with acrylic ester copolymers. The ultraviolet light absorbed by the ultraviolet absorber weakens the ultraviolet light reaching the inner layer of the paint film, resulting in a weakened polymerization reaction, thereby generating a crosslinking density that gradually decreases from the surface layer to the inner layer. The reduction in the crosslinking density of the inner layer weakens the shrinkage stress of the inner layer of the paint film, and the paint film has a stronger adhesion to the underlying substrate or coating. The yellowing-resistant acrylic raw materials, ultraviolet absorber and non-alkaline hindered amine free radical scavenger act synergistically. The paint film itself has excellent yellowing resistance, strong ultraviolet absorption and photolysis active free radical elimination capabilities, which can protect the base material at the bottom of the paint film from discoloration. Through the curing process of the coating, the micro-wrinkles on the surface of the paint film caused by the shrinkage of the high-functionality acrylate polymerization reaction can be greatly reduced, making the surface of the paint film flat and smooth, and the coating effect is excellent. The curing process of the coating isolates the air, avoids oxygen inhibition, makes the surface of the paint film highly cross-linked, and reduces the amount of photoinitiator used, reducing the impact of the initiator decomposition products on the yellowing resistance of the paint film. The smooth paint film surface, extremely high surface cross-linking density and high-hardness aluminum oxide powder work synergistically, so that the paint film has a hardness of not less than 5H, or even up to 6H, and is not easy to crack after hot and cold cycles.

[0010] A first aspect of the present invention provides a yellowing-resistant, high-hardness UV film-coating varnish.

[0011] Specifically, a yellowing-resistant, high-hardness UV coating varnish includes hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin, acrylate reactive diluent, filler, ultraviolet absorber, non-alkaline hindered amine free 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 reactive diluent is (2.5-3.5):(1-1.5):0.5:(2.0-3.0);

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

[0014] Preferably, 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 (2.8-3.2):(1.1-1.4):0.5:(2.2-2.8).

[0015] Preferably, 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 an inhibitor, heating, and when -NCO is 0, adding 6-hexanediol diacrylate, stirring, and obtaining the difunctional linear polyurethane acrylic resin.

[0016] Preferably, the isocyanate includes at least one of hexamethylene diisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

[0017] Preferably, the organic bismuth catalyst includes at least one of bismuth laurate, bismuth isooctanoate, and bismuth cyclohexaneate.

[0018] Preferably, the reaction temperature is 50-65°C, more preferably 55-65°C.

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

[0020] Preferably, the polymerization inhibitor comprises hydroquinone.

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

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

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

[0024] Preferably, the preparation method of the difunctional linear polyurethane acrylic resin comprises the following steps:

[0025] 168 kg of hexamethylene diisocyanate and 1 kg of catalyst organic bismuth are added into the reactor, the temperature is raised to 35-40°C, 1250 kg of poly 1,4-butanediol (relative molecular weight 2500) is slowly added, and after reacting for 2 hours, the temperature is raised to 65°C. When the -NCO residual amount is close to 50%, 120 kg of hydroxyethyl acrylate and 1.7 kg of inhibitor hydroquinone are added, the temperature is raised to 85°C until the -NCO value is zero, and then 330 kg of 1,6-hexanediol diacrylate is added, and the material is discharged after stirring evenly.

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

[0027] The above pure acrylic resin can be provided by Jiangxi Kunlong New Materials Co., Ltd., model HM-3624.

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

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

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

[0031] Preferably, the non-alkaline hindered amine free radical scavenger is BASF's TiNUVIN 249. TiNUVIN 249 is a liquid, has good compatibility with acrylic ester substances, can quickly process active free radicals generated by the photolysis reaction of the paint film, and protect the paint film from being easily photolyzed.

[0032] Preferably, the dispersant is a modified polyester polymer solution, such as AFCONA-4053 from EFCONA.

[0033] Preferably, the defoamer is an organic polymer solution TEGO Airex 920. The defoamer does not contain silicone, does not affect the adhesion of the topcoat on the primer, has high defoaming efficiency, and also has good compatibility, and does not affect recoating.

[0034] Preferably, the anti-settling aid is BYK Chemical's RHEOBYK-405. RHEOBYK-405 is in liquid form, easy to add, can improve the efficacy of gas silicon, and effectively prevent powder from settling.

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

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

[0037] Preferably, the leveling agent is an acrylic leveling agent, such as BYK-358N from BYK Chemical. The leveling agent slightly reduces the surface tension, does not affect the adhesion between the paint film layers, and does not affect the recoatability. It has good compatibility with acrylic substances and will not cause turbidity in the varnish.

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

[0039] Pentaerythritol triacrylate, an organic bismuth catalyst and a polymerization inhibitor are mixed, and then isocyanate is added and the temperature is raised to react to obtain the hexafunctional alicyclic polyurethane acrylic resin.

[0040] Preferably, the weight ratio of pentaerythritol triacrylate, organic bismuth catalyst, inhibitor and isocyanate is 850:(0.1-0.5):(0.5-1.5):(200-240), and more 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, more preferably 75-85°C.

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

[0043] 850 kg of pentaerythritol triacrylate, 0.2 kg of organic bismuth catalyst and 1 kg of inhibitor hydroquinone are sequentially added into the reactor, the temperature is raised to 35-40 ° C, 222 kg of isophorone diisocyanate is slowly added, after stirring evenly, the temperature is raised to 85 ° C, and the material can be discharged when the -NCO value is zero.

[0044] The unreacted pentaerythritol triacrylate plays the role of diluting the resin, reducing the viscosity and increasing the hardness of the resin. The synthesis process of the hexafunctional alicyclic polyurethane acrylic resin has simple procedures, high efficiency, and is easy to process, operate, control and use.

[0045] Preferably, the UV coating varnish comprises the following components in parts by weight:

[0046] 25-35 parts of hexafunctional alicyclic polyurethane acrylic resin;

[0047] 10-15 parts of difunctional linear polyurethane acrylic resin;

[0048] 5 parts of pure acrylic resin;

[0049] Acrylate reactive diluent 20-30 parts;

[0050] 0.8-1.2 parts of ultraviolet absorber;

[0051] 0.8-1.2 parts of non-alkaline hindered amine free radical scavenger;

[0052] 20-25 parts of filler.

[0053] Further preferably, the UV coating varnish comprises the following components in parts by weight:

[0054] 25-35 parts of hexafunctional alicyclic polyurethane acrylic resin;

[0055] 10-15 parts of difunctional linear polyurethane acrylic resin;

[0056] 5 parts of pure acrylic resin;

[0057] Acrylate reactive diluent 20-30 parts;

[0058] 0.8-1.2 parts of ultraviolet absorber;

[0059] 0.8-1.2 parts of non-alkaline hindered amine free radical scavenger;

[0060] Dispersant 0.5-1 part;

[0061] Defoaming agent 0.1-0.3 parts;

[0062] 20-25 parts of filler;

[0063] Anti-settling agent 0.05-0.1 part;

[0064] 0.3-0.5 parts of fumed silica;

[0065] 4-5 parts of photoinitiator;

[0066] 0.2-0.4 parts of leveling agent.

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

[0068] Specifically, a method for preparing a yellowing-resistant, high-hardness UV coating varnish comprises the following steps:

[0069] The components are mixed to obtain the UV film-coating varnish.

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

[0071] Step 1: Put hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, acrylic resin, and acrylic ester reactive diluent into a container (such as a dispersion tank), and disperse at 600-800 r / min for 5-8 minutes;

[0072] Step 2: Slowly add dispersant, defoamer and anti-settling agent, and disperse at 600-800r / min for 5-8min;

[0073] Step 3: Slowly add filler and fumed silica, adjust the speed to 1300-1500r / min, and disperse for 25-35 minutes;

[0074] Step 4: adjust the speed to 600-800r / min, add the photoinitiator, the remaining acrylate reactive diluent, the ultraviolet absorber, the non-alkaline hindered amine radical scavenger and the leveling agent in sequence, and disperse for 5-8 minutes to obtain the UV coating varnish.

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

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

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

[0078] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0079] (1) The UV coating varnish of the present invention uses a hexafunctional alicyclic polyurethane acrylic resin as the main resin, and is matched with a difunctional linear polyurethane acrylic resin, a pure acrylic resin and an acrylate reactive diluent in a specific ratio. The difunctional linear polyurethane acrylic resin is prepared by a specific method, so that the UV coating varnish of the present invention can simultaneously meet the requirements of good yellowing resistance and high hardness performance, with a hardness of not less than 5H and even up to 6H, and is not easy to crack after being subjected to cold and hot cycles.

[0080] (2) The paint film formed after curing of the UV coating varnish of the present invention has excellent yellowing resistance, 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 the excellent yellowing resistance of the paint film and curbing the discoloration of the bottom paint film, pattern and substrate, it also has high hardness, effectively preventing sharp objects from damaging the paint film. 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 invention uses the synergistic effect of the optimally proportioned hexafunctional alicyclic polyurethane resin, difunctional linear polyurethane acrylic resin, pure acrylic resin and acrylate reactive diluent, as well as a specific difunctional linear polyurethane acrylic resin preparation method, and is supplemented with high-hardness aluminum oxide powder, so that the hardness can be as high as 6H, and has good yellowing resistance, solving the problem of cracking and peeling. The combination of ultraviolet absorber and non-alkaline hindered amine free radical scavenger further enables the paint film to effectively protect the bottom layer from discoloration and improve adhesion. Among them, difunctional linear polyurethane acrylic resin and 1,6-hexanediol diacrylate give the paint film a certain toughness to avoid problems such as cracking and peeling of the paint film; pure acrylic resin and hydroxyethyl methacrylate can produce 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) Use a UV circulating film press for coating and curing to solve the problem of oxygen inhibition, reduce the amount of photoinitiator used, improve the curing quality of the coating surface, reduce the micro-wrinkles on the paint film surface caused by shrinkage due to the curing reaction, and improve the flatness of the paint film surface.

[0083] (4) High-hardness alumina powder is used. 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 curing reaction, and improve adhesion. It can also enhance the paint film's absorption and reflection of ultraviolet rays and enhance the paint film's protective effect on the bottom coating and substrate. DETAILED DESCRIPTION

[0084] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

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

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

[0087] Pure acrylic resin was provided by Jiangxi Kunlong New Materials Co., Ltd., model 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 dispersant is AFCONA-4053 from Efcona.

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

[0093] The anti-settling agent is RHEOBYK-405 from BYK Chemical.

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

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

[0096] The organic bismuth catalyst is bismuth laurate.

[0097] The photoinitiators used were 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone) and MBF (methyl benzoylformate).

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

[0099] 850 kg of pentaerythritol triacrylate, 0.2 kg of organic bismuth catalyst and 1 kg of inhibitor hydroquinone were sequentially added into the reactor, the temperature was raised to 40°C, 222 kg of isophorone diisocyanate was slowly added, and after stirring evenly, the temperature was raised to 85°C. When the -NCO value was zero, the material could be discharged to obtain a hexafunctional alicyclic 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 into the reactor, the temperature was raised to 40°C, 1250 kg of poly 1,4-butanediol (relative molecular weight 2500) was slowly added, and after reacting for 2 hours, the temperature was raised to 65°C. When the -NCO residual amount was 50%, 120 kg of hydroxyethyl acrylate and 1.7 kg of 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 the material was 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 copies;

[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 1: Put hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin and 1,6-hexanediol diacrylate into a dispersion tank in order, and disperse at 700 r / min for 6 minutes;

[0121] Step 2: Slowly add dispersant, defoamer and anti-settling agent, and disperse at 700r / min for 7 minutes;

[0122] Step 3: Slowly add filler alumina powder and fumed silica, adjust the speed to 1400r / min, and disperse for 30 minutes;

[0123] 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.

[0124] Example 2

[0125] A yellowing-resistant, high-hardness UV coating varnish, comprising the following components in parts by weight:

[0126] 30 parts of hexafunctional alicyclic polyurethane acrylic resin;

[0127] 12 parts of difunctional linear polyurethane acrylic resin;

[0128] 5 parts of pure acrylic resin;

[0129] 20 parts of 1,6-hexanediol diacrylate

[0130] 5 parts of Hydroxyethyl Methacrylate

[0131] 1 part of ultraviolet absorber;

[0132] 1 part of non-alkaline hindered amine free radical scavenger;

[0133] 0.8 parts of dispersant;

[0134] 0.2 parts of defoaming agent;

[0135] 22.5 parts of alumina powder;

[0136] 0.08 parts of anti-settling agent;

[0137] 0.4 parts of fumed silica;

[0138] 1173 2 copies;

[0139] MBF 2.5 parts;

[0140] 0.3 parts of leveling agent.

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

[0142] Step 1: Put hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin and 1,6-hexanediol diacrylate into a dispersion tank in 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 free radical scavenger;

[0156] 0.8 parts of dispersant;

[0157] 0.2 parts of defoaming agent;

[0158] 25 parts of alumina 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] 0.3 parts of leveling agent.

[0164] A method for preparing a yellowing-resistant, high-hardness UV coating varnish comprises the following steps:

[0165] Step 1: Put hexafunctional alicyclic polyurethane acrylic resin, difunctional linear polyurethane acrylic resin, pure acrylic resin and 1,6-hexanediol diacrylate into a dispersion tank in order, and disperse at 700 r / min for 6 minutes;

[0166] Step 2: Slowly add dispersant, defoamer and anti-settling agent, and disperse at 700r / min for 7 minutes;

[0167] Step 3: Slowly add filler alumina powder and fumed silica, adjust the speed to 1400r / min, and disperse for 30 minutes;

[0168] Step 4: Adjust the speed to 800r / min, add photoinitiator, hydroxyethyl methacrylate, pentaerythritol triacrylate, UV absorber, non-alkaline hindered amine free radical scavenger and leveling agent in sequence, and disperse for 8 minutes.

[0169] Comparative Example 1

[0170] The difference between this comparative example and Example 1 is that the hexafunctional alicyclic polyurethane acrylic resin in Comparative Example 1 is 15 parts by weight, and the other components and preparation process are the same as those in 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 in Comparative Example 2 is 5 parts by weight, and the remaining components and preparation process are the same as those in Example 1.

[0173] Comparative Example 3

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

[0175] Comparative Example 4

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

[0177] Comparative Example 5

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

[0179] Comparative Example 6

[0180] The only difference between this comparative example and Example 3 is that the difunctional linear polyurethane acrylic resin in Comparative Example 6 is 22 parts by weight, and the remaining components and preparation process are the same as those in Example 3.

[0181] Comparative Example 7

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

[0183] Comparative Example 8

[0184] The only difference between this comparative example and Example 3 is that the 1,6-hexanediol diacrylate in Comparative Example 8 is 30 parts by weight, and the hydroxyethyl methacrylate is 10 parts by weight, and the remaining components and preparation process are the same as those in Example 3.

[0185] Comparative Example 9

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

[0187] Comparative Example 10

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

[0189] Comparative Example 11

[0190] The difference between this comparative example and Example 1 is that the raw materials used in the preparation method of the difunctional linear polyurethane acrylic resin are different. The remaining components and processes are the same as those in Example 1.

[0191] The preparation method of the difunctional linear polyurethane acrylic resin of this comparative example comprises the following steps:

[0192] 168 kg of hexamethylene diisocyanate and 1 kg of organic bismuth catalyst were added into the reactor, the temperature was raised to 40°C, 1250 kg of poly 1,2-propylene glycol (relative molecular weight 2500) was slowly added, and after reacting for 2 hours, the temperature was raised to 65°C. When the -NCO residual amount was 50%, 120 kg of hydroxyethyl acrylate and 1.7 kg of 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 the material was discharged to obtain a difunctional linear polyurethane acrylic resin.

[0193] Product effect testing

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

[0195] Paint appearance: Tested in accordance with HG / T 3655-2012.

[0196] Pencil hardness: Tested in accordance with GB / T 6739-2006.

[0197] Yellowing resistance: Tested in accordance with GB / T 23983-2009.

[0198] To prevent the base from changing color: Apply UV coating varnish to the substrate with 3D printed patterns and cure it. Then expose the boards with and without UV coating varnish outdoors for 6 months and then test the color difference △E.

[0199] Hot and cold cycle test: Take three sample plates, each with a size of 30cm×20cm×1cm, and use a programmable constant temperature and humidity tester to produce alternating temperature and humidity cycles on the samples, and perform hot and cold cycle tests on the paint film formed by the UV coating varnish. After 5 cycles, describe the defects such as cracking and peeling of the paint film.

[0200] The performance test results of the paint films formed by the UV coating varnishes prepared in Examples 1-3 and Comparative Examples 1-11 are shown in Table 1.

[0201] Table 1

[0202]

[0203]

[0204] From the data in Table 1, it can be seen that the paint films of Examples 1-3 are normal and have a hardness of 5H or above.

[0205] From the comparison between Comparative Examples 1-8 and Examples 1 and 3, it can be seen that when 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 outside the ratio of (2.5-3.5):(1-1.5):0.5:(2.0-3.0), the paint film performance will be seriously degraded or the paint film will be abnormal.

[0206] From the comparison between Comparative Example 9 and Example 3, it can be seen that adding a proper amount of TiNUVIN 400 can efficiently absorb most of the ultraviolet rays in sunlight and effectively protect the color of the bottom layer.

[0207] From the comparison between 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 between Comparative Example 11 and Example 1, it can be seen that the resin obtained by polymerization of hexamethylene diisocyanate, poly 1,4-butanediol (relative molecular weight 2500) and hydroxyethyl acrylate can give the paint film a certain toughness, solving the problem that the paint film is too brittle and easy to crack in hot and cold 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.

2. The UV film 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 -NCO is 0, adding 6-hexanediol diacrylate, stirring, and obtaining 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-butanediol and hydroxyethyl acrylate is 168:(1000-1400):(110-130).

5. The UV film 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 film 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 alumina powder; and / or, the UV coating varnish also includes at least one of a dispersant, an anti-settling aid, fumed silica, and a leveling agent.

7. The UV film coating varnish according to claim 1, characterized in that: 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; Acrylate reactive diluent 20-30 parts; 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 film coating varnish according to claim 6, characterized in that: The UV coating varnish further comprises a dispersant, an anti-settling aid, fumed silica and a leveling agent, and the UV coating varnish comprises 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; Acrylate reactive diluent 20-30 parts; 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.

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