Yellowing-resistant and high-temperature-resistant UV curing coating and preparation method thereof

Abstract

The invention discloses a yellowing-resistant and high-temperature-resistant UV curing coating and a preparation method thereof. The yellowing-resistant and high-temperature-resistant UV curing coating is prepared from the following components in percentage by weight: 40.0 to 70.0 percent of o-cresol formaldehyde acrylic resin (EOCA), 10.0 to 30 percent of reactive diluent, 1 to 6 percent of photoinitiator, 0.1 to 0.5 percent of flatting agent, 0.1 to 0.5 percent of defoaming agent, 0.2 to 1 percent of dispersing agent, 0.5 to 2 percent of yellowing-resistant agent and 10 to 30 percent of filler. The o-cresol formaldehyde acrylic resin is prepared from the following components in percentage by weight: 20 to 60 percent of o-cresol formaldehyde epoxy resin, 20 to 40 percent of 3, 4-dimethoxycinnamic acid, 10 to 30 percent of diluent, 0.1 to 0.6 percent of catalyst, 0.5 to 2 percent of polymerization inhibitor and 10 to 30 percent of tetrahydrophthalic anhydride. The yellowing-resistant and high-temperature-resistant UV curing coating provided by the invention is high in coating film curing speed and excellent in thermal stability and yellowing resistance.

Description

Technical Field

[0001] The invention relates to the field of yellowing-resistant and high-temperature-resistant UV curing coatings, and in particular to a yellowing-resistant and high-temperature-resistant UV curing coating and a preparation method thereof. Background Art

[0002] UV curing technology originated in the 1960s. It is a new technology with the characteristics of economy, energy saving and environmental protection. Its basic principle is to expose a liquid matrix containing unsaturated carbon-carbon double bonds to ultraviolet light. After the photoinitiator absorbs the radiation energy, it is excited to produce free radicals or cations, which in turn triggers a chemical reaction between the unsaturated carbon-carbon double bonds in the liquid matrix, and forms a solid structure after cross-linking and curing. UV curing coatings are a new type of coating developed from this principle. It uses ultraviolet light to cause a chemical reaction in the liquid matrix containing unsaturated carbon-carbon double bonds, thereby achieving cross-linking and curing. UV curing coatings have the advantages of fast curing speed, mild curing conditions, energy saving, saving floor space, no pollution to the environment, and improved product performance. They are widely used in electronic products (such as circuit board coating, screen protection and shell coating, etc.), wood products, floor coatings, packaging printing, publication printing, commercial printing and other fields. With the increasing global environmental awareness and increasingly stringent environmental regulations, the electronics manufacturing industry has put forward higher requirements for the environmental performance of coatings. With the continuous upgrading of electronic products and the strengthening of the intelligent trend, the market demand for high-end electronic circuit boards is growing, which also makes UV curing coatings develop towards high performance [Chinese Chemical Letters, 2007, 18 (5): 598-600.]. In some special fields, such as printed circuit board processing, it is necessary to undergo high-temperature reflow soldering at 200 to 260 ° C. This requires that the cured solder mask ink not only has high insulation performance, but also has to resist the high-temperature heat treatment of reflow soldering. For character inks, the surface will oxidize and turn yellow during high-temperature treatment and long-term use, affecting the appearance of the product [CN 109517140 A]. Summary of the invention

[0003] The object of the present invention is to provide a yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof.

[0004] The invention also provides a high temperature resistant UV curing o-cresol aldehyde acrylic resin and a preparation method thereof, which has fast curing speed and excellent heat resistance.

[0005] The present invention proposes to introduce double bonds into the matrix o-cresol epoxy resin by the nucleophilic addition reaction of carboxyl and epoxy groups, so that it has the characteristics of photo-initiated polymerization, and at the same time, 3,4-methoxybenzene rings with large steric hindrance are also grafted onto the o-cresol epoxy resin, so that the molecular chain segments are not easy to rotate and move freely when heated, thereby improving the heat resistance of the resin and obtaining a UV-cured resin with high strength and excellent thermal stability. Since the unreacted unsaturated double bonds and benzene ring structures are easily oxidized and yellowed under high temperature and long-term use, in order to solve the yellowing phenomenon of high-heat-resistant UV-cured resins, the technology of the present invention improves the conversion rate of unsaturated double bonds and reduces the occurrence of yellowing by studying the photocuring kinetics of o-cresol acrylic resin. At the same time, in order to solve the problem of benzene rings being easily oxidized and yellowed, BASF 1010 is used as the main anti-yellowing agent in the system to capture the peroxy free radicals generated in the thermal oxidation process, thereby preventing the degradation reaction of the material and preventing the yellowing of the material. In order to achieve the best anti-yellowing effect, the auxiliary antioxidant BASF 168 is added to the system to decompose hydroperoxides, thereby producing a synergistic effect with the main anti-yellowing agent BASF 1010, making the yellowing resistance of UV-curing resin optimal.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides an o-cresol-formaldehyde acrylic resin, comprising the following components in percentage by weight:

[0008]

[0009] Further preferably, an o-cresol-formaldehyde acrylic resin comprises the following components in percentage by weight:

[0010]

[0011] Preferably, in the o-cresol-formaldehyde acrylic resin, the diluent is diethylene glycol monoethyl ether acetate.

[0012] Preferably, in the o-cresol-formaldehyde acrylic resin, the catalyst is triphenylphosphine.

[0013] Preferably, in the o-cresol-formaldehyde acrylic resin, the polymerization inhibitor is p-hydroxyanisole.

[0014] In a second aspect, a method for preparing an o-cresol-formaldehyde acrylic resin comprises the following steps:

[0015] 1) Add o-methylphenolic epoxy resin and diluent into the reactor and stir at 85-95°C for 25-35 minutes;

[0016] 2) Add 3,4-dimethoxyphenylacrylic acid, catalyst and inhibitor, stir at 85-95°C for 25-35 minutes, raise the temperature to 100-110°C and keep the temperature constant for 8-12 hours, and stir;

[0017] 3) Add tetrahydrophthalic anhydride, react at 85-95°C for 4-6h, and stir;

[0018] 4) Sampling and testing, titrating the product with potassium hydroxide ethanol solution to make the acid value less than 10 mgKOH / g; lowering the room temperature to obtain o-cresol aldehyde acrylic resin.

[0019] Most preferably, a method for preparing o-cresol-formaldehyde acrylic resin comprises the following steps:

[0020] 1) Add o-methylphenolic epoxy resin and diethylene glycol monoethyl ether acetate into a container and stir at 90°C for 30 minutes;

[0021] 2) Add 3,4-dimethoxyphenylacrylic acid, triphenylphosphine and p-hydroxyanisole and stir at 90°C for 30 minutes, raise the temperature to 105°C and keep the temperature constant for 10 hours while stirring;

[0022] 3) Add tetrahydrophthalic anhydride, react at 90°C for 5h, and stir;

[0023] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0024] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin.

[0025] Preferably, the synthetic route of the preparation method reaction is:

[0026]

[0027] In a third aspect, a yellowing-resistant and high-temperature-resistant UV-curing coating comprises the following components in weight percentage:

[0028]

[0029] Further preferably, the yellowing-resistant and high-temperature-resistant UV-curing coating comprises the following components in percentage by weight:

[0030]

[0031]

[0032] Preferably, in the yellowing-resistant and high-temperature-resistant UV-curing coating, the photoinitiator is one or more of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) or 1-hydroxycyclohexyl phenyl ketone (184); and the active diluent is ethoxylated trimethylolpropane triacrylate.

[0033] Preferably, in the yellowing-resistant and high-temperature-resistant UV-curing coating, the leveling agent is BYK-450; the defoaming agent is BASF 2410AC; the anti-yellowing agent is one or more of BASF 1010 and BASF 168; the filler is titanium dioxide; and the dispersant is BYK-110.

[0034] A method for preparing a yellowing-resistant and high-temperature-resistant UV-curing coating comprises the following steps:

[0035] 1) Under yellow light environment, mix the photoinitiator and active diluent evenly;

[0036] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoaming agent and dispersant to the solution prepared in step 1) and mix well;

[0037] 3) Add the anti-yellowing agent and filler to the solution prepared in step 2) and mix well to obtain a premix;

[0038] 4) Transfer the premix to a grinder for grinding to obtain a dispersed premix;

[0039] 5) Mix the dispersed premix under vacuum to obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0040] In step 1), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds;

[0041] In step 2), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds;

[0042] In step 3), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds;

[0043] In step 5), the mixing condition under vacuum is: mixing with a homogenizer at 1200-1800 rpm under vacuum for 240-480 seconds.

[0044] Most preferably, a yellowing-resistant and high-temperature-resistant UV-curable coating and a preparation method thereof, the method comprising the following steps:

[0045] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0046] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0047] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0048] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0049] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0050] Compared with the prior art, the present invention has the following advantages:

[0051] 1. The o-cresol-formaldehyde acrylic resin of the present invention introduces double bonds into the matrix o-cresol-formaldehyde epoxy resin through the nucleophilic addition reaction of carboxyl and epoxy groups, so that the matrix has the property of photoinitiated polymerization, and at the same time, the 3,4-methoxybenzene ring with large steric hindrance is also grafted onto the o-cresol-formaldehyde epoxy resin, so that the molecular chain segments are not easy to rotate and move freely when heated, thereby improving the heat resistance of the resin, and obtaining a UV-curable resin with high strength and excellent thermal stability.

[0052] 2. A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof of the present invention, wherein the preparation method is simple. Unreacted unsaturated double bonds and benzene ring structures in UV-curing resins are easily oxidized and yellowed at high temperatures and under long-term use. The rigidity of the benzene ring determines the heat resistance and strength of the resin. In order to solve the yellowing phenomenon of high-heat-resistant UV-curing resins, the technology of this application studies the photocuring kinetics of o-cresol aldehyde acrylic resin, improves the conversion rate of unsaturated double bonds, and reduces the occurrence of yellowing. At the same time, in order to solve the problem of benzene rings being easily oxidized and yellowed, BASF 1010 is used as the main anti-yellowing agent in the system to capture the peroxy radicals generated during the thermal oxidation process, thereby preventing the degradation reaction of the material and preventing the yellowing of the material. In order to achieve the best anti-yellowing effect, an auxiliary antioxidant BASF 168 is added to the system, which can decompose hydroperoxides, thereby producing a synergistic effect with the main anti-yellowing agent BASF 1010, so that the anti-yellowing effect of the UV-curing resin is optimal. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 FT-IR spectra of cured films with different photoinitiator dosages.

[0054] Figure 2 This is the effect of different photoinitiator dosages on the double bond conversion rate of the cured film.

[0055] Figure 3 This is the synthetic FT-IR spectrum of o-cresol-formaldehyde epoxy acrylic resin. DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with specific embodiments:

[0057] Embodiment 1:

[0058] A preparation method of o-cresol aldehyde acrylic resin:

[0059] 1) Add o-methylphenolic epoxy resin (Hubei Hongxin Ruiyu Fine Chemical Co., Ltd., industrial grade) and diethylene glycol monoethyl ether acetate (Wuhan Smack Biotechnology Co., Ltd., industrial grade) into the container and stir at 90°C for 30 minutes;

[0060] 2) Add 3,4-dimethoxyphenylacrylic acid (Shanghai Aladdin Biochemical Technology Co., Ltd., ≥95%), triphenylphosphine (Shanghai Aladdin Biochemical Technology Co., Ltd., ≥95%) and p-hydroxyanisole (Shanghai Aladdin Biochemical Technology Co., Ltd., analytical grade 99%), stir at 90°C for 30 minutes, raise the temperature to 105°C and keep the temperature for 10 hours, and stir;

[0061] 3) Add tetrahydrophthalic anhydride (Shanghai Aladdin Biochemical Technology Co., Ltd., ≥95%), react at 90°C for 5h, and stir;

[0062] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0063] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin (EOCA).

[0064] FT-IT Synthesis Characterization of o-cresol-formaldehyde Epoxy Acrylic Resin:

[0065] The synthetic infrared spectrum of EOCA is shown in Figure 3As shown, in the infrared spectrum of 3,4-DMPA, the stretching vibration peak of the carboxyl group (-COOH) in acrylic acid appears at 1700cm-1, the stretching vibration peak of the double bond (C=C) in acrylic acid appears at 1635cm-1, and the stretching vibration peak of the epoxy group COC appears at 910cm-1 in the infrared spectrum of EOCN. In the infrared spectrum of the product EOCA, ​​the stretching vibration peak of the epoxy group COC at 910cm-1 disappears, and new peaks appear at 1720cm-1 and 1635cm-1, respectively. The stretching vibration peak at 1720cm-1 belongs to the ester bond (C=O), and the stretching vibration peak at 1635cm-1 belongs to the double bond (C=C). The disappearance of the above-mentioned epoxy characteristic peaks and the appearance of the ester bond and double bond peaks indicate that the carboxyl group of 3,4-DMPA and the epoxy group of EOCN undergo esterification reaction, the epoxy group of EOCN is opened by the carboxyl group of AA, and the double bond of 3,4-DMPA is successfully grafted into EOCA.

[0066] A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof:

[0067] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0068] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0069] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0070] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0071] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0072] Embodiment 2:

[0073] A preparation method of o-cresol aldehyde acrylic resin:

[0074] 1) Add o-methylphenolic epoxy resin and diethylene glycol monoethyl ether acetate into a container and stir at 90°C for 30 minutes;

[0075] 2) Add 3,4-dimethoxyphenylacrylic acid, triphenylphosphine and p-hydroxyanisole, stir at 90°C for 30 minutes, raise the temperature to 100°C and keep the temperature constant for 10 hours while stirring;

[0076] 3) Add tetrahydrophthalic anhydride, react at 90°C for 5h, and stir;

[0077] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0078] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin.

[0079] A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof:

[0080] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0081] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0082] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0083] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0084] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0085] Embodiment 3:

[0086] A preparation method of o-cresol aldehyde acrylic resin:

[0087] 1) Add o-methylphenolic epoxy resin and diethylene glycol monoethyl ether acetate into a container and stir at 90°C for 30 minutes;

[0088] 2) Add 3,4-dimethoxyphenylacrylic acid, triphenylphosphine and p-hydroxyanisole, stir at 90°C for 30 minutes, raise the temperature to 105°C and keep constant for 9 hours while stirring;

[0089] 3) Add tetrahydrophthalic anhydride, react at 90°C for 5h, and stir;

[0090] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0091] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin.

[0092] A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof:

[0093] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0094] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0095] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0096] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0097] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0098] Embodiment 4:

[0099] A preparation method of o-cresol aldehyde acrylic resin:

[0100] 1) Add o-methylphenolic epoxy resin and diethylene glycol monoethyl ether acetate into a container and stir at 90°C for 30 minutes;

[0101] 2) Add 3,4-dimethoxyphenylacrylic acid, triphenylphosphine and p-hydroxyanisole and stir at 90°C for 30 minutes, raise the temperature to 105°C and keep the temperature constant for 10 hours while stirring;

[0102] 3) Add tetrahydrophthalic anhydride, react at 100°C for 5h, and stir;

[0103] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0104] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin.

[0105] A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof:

[0106] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0107] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0108] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0109] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0110] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0111] Embodiment 5:

[0112] A preparation method of o-cresol aldehyde acrylic resin:

[0113] 1) Add o-methylphenolic epoxy resin and diethylene glycol monoethyl ether acetate into a container and stir at 90°C for 30 minutes;

[0114] 2) Add 3,4-dimethoxyphenylacrylic acid, triphenylphosphine and p-hydroxyanisole and stir at 90°C for 30 minutes, raise the temperature to 105°C and keep the temperature constant for 10 hours while stirring;

[0115] 3) Add tetrahydrophthalic anhydride, react at 90°C for 6h, and stir;

[0116] 4) Sampling and testing, using 0.1 mol·L -1 The product is titrated with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g;

[0117] 5) After cooling to room temperature, transfer to a brown reagent bottle to obtain o-cresol aldehyde acrylic resin.

[0118] A yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof:

[0119] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0120] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0121] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0122] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0123] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0124] Table 1: Weight ratio of UV curable resin components in Examples 1-5

[0125] Example 1 Example 2 Example 3 Example 4 Example 5 o-Methylphenolic epoxy resin 29.55wt% 28.55wt% 30.5wt% 31.5wt% 28.5wt% 3,4-Dimethoxyphenylacrylic acid 31.5wt% 32.0wt% 31.5wt% 30.5wt% 31.5wt% Thinner 26.15wt% 26.25wt% 25.2wt% 26.2wt% 27.2wt% catalyst 0.4wt% 0.3wt% 0.3wt% 0.4wt% 0.4wt% Inhibitor 1.0wt% 1.0wt% 1.0wt% 1.0wt% 1.0wt% Tetrahydrophthalic anhydride 11.4wt% 11.9wt% 11.5wt% 10.4wt% 11.4wt%

[0126] Table 2: Weight ratio of UV curing coating components in Examples 1-5

[0127] Example 1 Example 2 Example 3 Example 4 Example 5 o-Methylphenolic acrylic resin 57.1wt% 56.1wt% 55.1wt% 54.1wt% 53.1wt% Active diluent 20.0wt% 20.0wt% 20.0wt% 20.0wt% 20.0wt% Photoinitiator 1.0wt% 2.0wt% 3.0wt% 4.0wt% 5.0wt% BYK-450 0.2wt% 0.2wt% 0.2wt% 0.2wt% 0.2wt% Defoaming agent 0.2wt% 0.2wt% 0.2wt% 0.2wt% 0.2wt% BYK-110 0.5wt% 0.5wt% 0.5wt% 0.5wt% 0.5wt% BASF 1010 0.5wt% 0.6wt% 0.7wt% 0.8wt% 0.9wt% BASF 168 0.5wt% 0.4wt% 0.3wt% 0.2wt% 0.1wt% Titanium dioxide 20.0wt% 20.0wt% 20.0wt% 20.0wt% 20.0wt%

[0128] The UV curing film performance tests of Examples 1-5 are shown in Table 3:

[0129] 1. Weigh each component according to the weight ratio of each component in Table 2

[0130] 1) Under yellow light, mix the photoinitiator and active diluent with a homogenizer at 2500 rpm for 60 seconds to dissolve the initiator and fully mix it in the active diluent;

[0131] 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant, and mix at a high speed of 2500 rpm in a homogenizer for 60 seconds to fully mix the o-cresol aldehyde acrylic resin, leveling agent, defoamer and dispersant;

[0132] 3) Add anti-yellowing agent and filler and mix at 2500 rpm for 60 seconds to obtain a premix;

[0133] 4) Transfer the premix to a three-roll mill to fully disperse the anti-yellowing agent and filler;

[0134] 5) The dispersed premix was mixed with a homogenizer at 1500 rpm under vacuum for 360 seconds to fully remove bubbles and obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

[0135] 2. UV curing film forming process:

[0136] 1) Use an automatic applicator and a 60μm wire rod to scrape the UV curing coating on the PET release film at a speed of 30m / min. Use a high-pressure mercury lamp as the UV light source with a light intensity of 25mW / cm -2 Curing of coating film.

[0137] Table 3: The performance test results of UV-cured coatings of Examples 1-5 are shown in the following table:

[0138]

[0139] Note: The yellowing test conditions are 120℃, 100% humidity, and aging for 24h.

[0140] The o-cresol-formaldehyde acrylic resin of the present invention introduces double bonds into a matrix o-cresol-formaldehyde epoxy resin through a nucleophilic addition reaction of a carboxyl group and an epoxy group, so that the matrix has a light-initiated polymerization property, and a 3,4-methoxybenzene ring with a large steric hindrance is also grafted onto the o-cresol-formaldehyde epoxy resin, so that the molecular chain segments are not easy to rotate and move freely when heated, thereby improving the heat resistance of the resin, and obtaining a UV-curable resin with high strength and excellent thermal stability.

[0141] Since the ester bond does not participate in the reaction during the photocuring process, the double bond polymerizes. Reflected in the infrared spectrum, the intensity of the ester bond peak does not change, while the intensity of the double bond peak will continue to decrease. Therefore, the ester bond peak is used as the internal standard to monitor the change in the peak intensity of the double bond to monitor the photocuring kinetics of the cured film, and the double bond conversion rate (C R )

[0142]

[0143] In the formula, C R is the conversion rate of C=C double bond; (A 1635 / A 1730 )0 is the absorption peak area ratio of C=O and C=C measured by FT-IR when the coating film is not cured, (A 1635 / A 1730 ) t It is the absorption peak area ratio of C=O and C=C measured by FT-IR when the coating film is exposed to UV for time t. Figure 1 FT-IR spectra of cured films with different photoinitiator dosages. Figure 1 It can be seen that with the addition of different amounts of initiator, the double bond peak area gradually decreases with the increase of curing time, which means that the double bond gradually participates in the polymerization. Figure 2 The effect of different photoinitiator dosages on the double bond conversion rate of the cured film is shown in Figure 2. Figure 2 It can be seen that when the amount of initiator is 4wt%, the conversion rate of double bonds is the highest. Therefore, in the yellowing-resistant and high-temperature-resistant UV-curing coating of the present invention, the amount of initiator is preferably 4wt%.

[0144] The present invention discloses a yellowing-resistant and high-temperature-resistant UV-curing coating and a preparation method thereof, and the preparation method thereof is simple. Unreacted unsaturated double bonds and benzene ring structures in UV-curing resins are easily oxidized and yellowed at high temperatures and under long-term use. The rigidity of the benzene ring determines the heat resistance and strength of the resin. In order to solve the yellowing phenomenon of high-heat-resistant UV-curing resins, the present invention studies the photocuring kinetics of o-cresol aldehyde acrylic resin to improve the conversion rate of unsaturated double bonds and reduce the occurrence of yellowing. At the same time, in order to solve the problem of benzene rings being easily oxidized and yellowed, BASF 1010 is used as the main anti-yellowing agent in the system to capture peroxy radicals generated in the thermal oxidation process, thereby preventing the degradation reaction of the material and preventing the yellowing of the material. In order to achieve the best anti-yellowing effect, an auxiliary antioxidant BASF 168 is added to the system to decompose hydroperoxides, thereby producing a synergistic effect with the main anti-yellowing agent BASF 1010, so that the anti-yellowing effect of the UV-curing resin is optimal.

Claims

1. A yellowing-resistant and high-temperature-resistant UV-curing coating, characterized in that: Made of the following components in weight percentage:

2. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The photoinitiator is one or two of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and 1-hydroxycyclohexyl phenyl ketone.

3. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The active diluent is ethoxylated trimethylolpropane triacrylate.

4. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The leveling agent is BYK-450; The defoamer is BASF 2410AC; The dispersant is BYK-110.

5. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The anti-yellowing agent is one or both of BASF 1010 and BASF 168.

6. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The filler is titanium dioxide.

7. The yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 1, characterized in that: The o-cresol aldehyde acrylic resin is made of the following raw materials in weight percentage: The diluent is diethylene glycol monoethyl ether acetate; The catalyst is triphenylphosphine; The polymerization inhibitor is p-hydroxyanisole.

8. The method for preparing the yellowing-resistant and high-temperature-resistant UV-curing coating according to any one of claims 1 to 7, characterized in that: The steps include: 1) Under yellow light environment, mix the photoinitiator and active diluent evenly; 2) Add o-cresol aldehyde acrylic resin, leveling agent, defoaming agent and dispersant to the solution prepared in step 1) and mix well; 3) Add the anti-yellowing agent and filler to the solution prepared in step 2) and mix well to obtain a premix; 4) Transfer the premix to a grinder for grinding to obtain a dispersed premix; 5) Mix the dispersed premix under vacuum to obtain a yellowing-resistant and high-temperature-resistant UV-curing coating.

9. The method for preparing the yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 8, characterized in that: In step 2), the preparation of the o-cresol-formaldehyde acrylic resin comprises the following steps: 2.1) Add o-methylphenolic epoxy resin and diluent into the reactor and stir at 85-95°C for 25-35 minutes; 2.2) Add 3,4-dimethoxyphenylacrylic acid, catalyst and inhibitor, stir at 85-95℃ for 25-35min, raise the temperature to 100-110℃ and keep constant temperature for 8-12h, and stir; 2.3) Add tetrahydrophthalic anhydride, react at 85-95°C for 4-6h, and stir; 2.4) Sampling and testing, titrating the product with potassium hydroxide ethanol solution to make the acid value <10 mgKOH / g; lowering the room temperature to obtain o-cresol aldehyde acrylic resin.

10. The method for preparing the yellowing-resistant and high-temperature-resistant UV-curing coating according to claim 9, characterized in that: In step 1), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds; In step 2), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds; In step 3), the conditions for uniform mixing are: mixing at a high speed of 2000 to 3000 rpm with a homogenizer for 40 to 80 seconds; In step 5), the mixing condition under vacuum is: mixing with a homogenizer at 1200-1800 rpm under vacuum for 240-480 seconds.

Images