UV ink and preparation method thereof

Abstract

The invention relates to UV ink and a preparation method thereof, and belongs to the technical field of UV ink. The preparation method of the UV ink comprises the following steps: heating and preheating isocyanate, adding an organic solvent, modified aluminum oxide, a catalyst and a polymerization inhibitor, uniformly mixing, stirring at a constant temperature, slowly adding an alcohol compound, continuously stirring, and carrying out rotary evaporation to remove the solvent to obtain a preform; and stirring and mixing the color paste, the preform, a reaction monomer and a photoinitiator, grinding, and filtering to obtain the photoinitiator. The modified aluminum oxide is adopted as the flame retardant, and the flame retardant is formed by compounding an inorganic aluminum oxide flame retardant and an organic flame retardant and has good compatibility with raw materials such as resin and monomers, so that the weather resistance and adhesive force of a coating are not affected while the coating formed after the UV ink is cured has flame retardance.

Description

Technical Field

[0001] The present invention belongs to the technical field of UV inks, and relates to a UV ink and a preparation method thereof. Background Art

[0002] Recently, ultraviolet (UV) curable inkjet inks have gradually become popular, which can be rapidly hardened under the irradiation of ultraviolet light. Such inks can be applied to a variety of materials, including soft films, leather, wallpapers, vehicle stickers, acrylic, PC boards, PVC boards, etc., to form an ink printing layer, and their applications in the printing field are gradually increasing. At present, UV curable inkjet inks have strong adhesion to materials and are not easily faded. However, for special materials such as UV painted fireproof decorative boards, they need to have certain fireproof performance, which are mainly used in hotels or interior decorations. However, most of the UV painted fireproof decorative boards on the market at present use UV curable inkjet inks with monomers and resins as basic components, which not only do not have flame retardancy, but also produce a large amount of black smoke and irritating gases harmful to the human body after combustion.

[0003] The patent document with the publication number CN115162025B specifically discloses a digital inkjet camouflage net and a preparation method thereof, belonging to the technical field of camouflage nets. A digital inkjet camouflage net includes a base cloth and a weather-resistant ink absorption layer, a UV ink layer, and a protective layer sequentially coated on the base cloth; the coating for the weather-resistant ink absorption layer includes: waterborne polyurethane, kaolin, titanium dioxide dispersion, talc powder, silicon dioxide, a composite flame retardant, and isocyanate; in this patent document, the composite flame retardant is obtained by mixing antimony trioxide and decabromodiphenylethane, and then adding magnesium hydroxide or aluminum hydroxide and stirring evenly. However, the compatibility of antimony trioxide, magnesium hydroxide or aluminum hydroxide with waterborne coatings such as polyurethane is poor, and when the addition ratio is large, it will affect the weather resistance and adhesion of the coating, thereby affecting the service life of the composite material. Summary of the Invention

[0004] The purpose of the present invention is to provide a UV ink and a preparation method thereof, which can form an ink printing layer with fireproof performance on a substrate, while ensuring good adhesion, weather resistance and flame retardancy.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of a UV ink includes the following steps:

[0007] S1. Under an inert atmosphere, preheat the isocyanate, add an organic solvent, modified alumina, a catalyst and a polymerization inhibitor, mix them evenly, stir at a constant temperature, slowly add an alcohol compound and continue stirring, and remove the solvent by rotary evaporation to obtain a preform;

[0008] S2. Stir and mix the color paste, preform, reactive monomer and photoinitiator, grind and then filter to obtain the product.

[0009] As a preferred technical solution of the present invention, in step S1, the inert atmosphere is a nitrogen atmosphere; the heating and preheating is to raise the temperature to 50 - 60 °C at a heating rate of 5 - 10 °C / min; the mixing is to stir and mix for 20 - 30 min; the constant temperature stirring is to stir at a constant temperature of 60 - 72 °C for 3 - 4 h; the continuous stirring is to continue stirring at 60 - 72 °C for 4 - 5 h.

[0010] As a preferred technical solution of the present invention, in step S1, the mass ratio of the isocyanate, organic solvent, modified alumina, catalyst, inhibitor and alcohol compound is (70 - 90):(45 - 60):(15 - 20):(0.02 - 0.04):(0.02 - 0.03):(25 - 30).

[0011] As a preferred technical solution of the present invention, in step S1, the isocyanate is one or both of IPDI and HDI; the inhibitor is hydroquinone; the alcohol compound is polyether diol, specifically DL - 3000 polyether polyol with a functionality of 2 and Mn = 3000, purchased from Shandong Bluestar Dongda Chemical Co., Ltd.; the organic solvent is ethyl acetate; the catalyst is an organotin catalyst, dibutyltin diacetate.

[0012] As a preferred technical solution of the present invention, in step S2, the reactive monomer is composed of methacrylate, 2 - hydroxyethyl acrylate and glycidyl methacrylate in a mass ratio of 12 - 14:2.0 - 2.3:1.5 - 2.0; the mass ratio of the color paste, preform, reactive monomer and photoinitiator is (20 - 26):(45 - 55):(100 - 115):(3 - 4); the methacrylate is selected from one or more of ethyl methacrylate, n - butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, lauryl methacrylate, butyl acrylate; in the present invention, ethyl methacrylate is used as the methacrylate, the photoinitiator is photoinitiator 1173, and the color paste is pigment red 122.

[0013] As a preferred technical solution of the present invention, in step S2, the stirring and mixing is to stir at 30 - 40 °C for 30 - 40 min; the grinding time is 1.5 - 2.0 h.

[0014] As a preferred technical solution of the present invention, the preparation method of the modified alumina includes the following steps:

[0015] Step 1: Add alumina and absolute ethanol into a reaction kettle, mix them evenly, then add a silane coupling agent and heat for reaction. Filter, wash with alcohol, and dry to obtain pretreated alumina.

[0016] Step 2: Under an inert atmosphere, ultrasonically disperse the pretreated alumina and absolute ethanol, add an aldehyde compound, heat and stir, centrifuge, wash, and then vacuum dry to obtain the product.

[0017] As a preferred technical solution of the present invention, in Step 1, the mass ratio of the alumina, absolute ethanol, and silane coupling agent is (15 - 18):(40 - 50):(5.0 - 6.2); the silane coupling agent is an amino-containing silane coupling agent.

[0018] As a preferred technical solution of the present invention, in Step 1, the heating reaction is carried out at 50 - 60°C for 5 - 6 h; the alcohol washing is carried out by rinsing with ethanol 3 times; the drying is carried out at 80°C for 10 - 12 h.

[0019] As a preferred technical solution of the present invention, in Step 2, the aldehyde compound is composed of 3,4,5-trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1; the 3,4,5-trihydroxybenzaldehyde is 3,4,5-trihydroxybenzaldehyde; the methacrolein is 2-methylacrolein; the mass ratio of the pretreated alumina, absolute ethanol, and aldehyde compound is (6 - 7):(20 - 30):(2.2 - 2.6).

[0020] As a preferred technical solution of the present invention, in Step 2, the inert atmosphere is a nitrogen atmosphere; the ultrasonic dispersion is carried out at an ultrasonic power of 150 - 300 W for 10 - 15 min; the heating and stirring are carried out at 55 - 65°C for 6 - 8 h; the washing is carried out by rinsing with ethyl acetate 3 times; the vacuum drying is carried out at 90°C until constant weight.

[0021] Advantages of the present invention:

[0022] The present invention uses modified alumina as a flame retardant. This flame retardant is composed of an inorganic alumina flame retardant and an organic flame retardant, and has good compatibility with raw materials such as resins and monomers. It can ensure that the coating formed after the UV ink is cured has flame retardant properties without affecting the weather resistance and adhesion of the coating.

[0023] In addition, when using the UV ink of the present invention for printing, an ink printing layer with flame retardant properties can be formed on special materials such as UV painted fireproof decorative boards. This printing layer not only has excellent fireproof performance but also can ensure good adhesion and weather resistance, thereby improving the use effect and service life of the UV painted fireproof decorative board. Detailed implementation manners

[0024] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in conjunction with embodiments, details the specific implementation manners, structures, features and their effects of the present invention as follows.

[0025] Example 1

[0026] A preparation method of UV ink comprises the following steps:

[0027] S1. Under a nitrogen atmosphere, the isocyanate is heated to 50°C at a heating rate of 5°C / min, ethyl acetate, modified alumina, organotin catalyst and hydroquinone are added and stirred for 20 min, then stirred at a constant temperature of 60°C for 3 h, polyether diol is slowly added and stirred at 60°C for another 4 h, and the solvent is removed by rotary evaporation to obtain a preform; the mass ratio of the isocyanate, ethyl acetate, modified alumina, organotin catalyst, hydroquinone and polyether diol is 70:45:15:0.02:0.02:25; the isocyanate is HDI; the organotin catalyst is dibutyltin diacetate;

[0028] S2. The color paste, preform, reaction monomer and photoinitiator are placed in a reaction kettle, stirred at 30°C for 30 min, ground for 1.5 h and then filtered to obtain the product; wherein, the reaction monomer is composed of methacrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate according to a mass ratio of 12:2.0:1.5; the mass ratio of the color paste, preform, reaction monomer and photoinitiator is 20:45:100:3.

[0029] The preparation method of the modified alumina comprises the following steps:

[0030] Step 1. Alumina and absolute ethanol are added to a reaction kettle and mixed evenly, then silane coupling agent KH550 is added, and then reacted at 50°C for 5 h, the solid matter is filtered out, rinsed 3 times with ethanol, and placed in an oven to be dried at 80°C for 10 h to obtain pretreated alumina; wherein, the mass ratio of the alumina, absolute ethanol and silane coupling agent is 15:40:5.0;

[0031] Step 2. Under a nitrogen atmosphere, the pretreated alumina and absolute ethanol are mixed evenly, treated with an ultrasonic power of 150 W for 10 min, an aldehyde compound is added and heated and stirred at 55°C for 6 h, the solid matter is centrifuged out, rinsed 3 times with ethyl acetate, and vacuum dried at 90°C to constant weight to obtain the product; wherein, the aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein according to a mass ratio of 3:1; the mass ratio of the pretreated alumina, absolute ethanol and aldehyde compound is 6:20:2.2.

[0032] Example 2

[0033] A preparation method of UV ink comprises the following steps:

[0034] S1. Under a nitrogen atmosphere, the isocyanate is heated to 55 °C at a heating rate of 8 °C / min, ethyl acetate, modified alumina, organotin catalyst and hydroquinone are added and stirred for 25 min, then stirred at a constant temperature of 65 °C for 3.5 h, polyether diol is slowly added and stirring is continued at 65 °C for 4.5 h, and the solvent is removed by rotary evaporation to obtain a preform; the mass ratio of the isocyanate, ethyl acetate, modified alumina, organotin catalyst, hydroquinone and polyether diol is 80:52:18:0.03:0.025:28; the isocyanate used is HDI; the organotin catalyst used is dibutyltin diacetate;

[0035] S2. The color paste, preform, reactive monomer and photoinitiator are placed in a reaction kettle, stirred at 35 °C for 35 min, ground for 1.8 h and then filtered to obtain the product; wherein, the reactive monomer is composed of methacrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate in a mass ratio of 13:2.2:1.8; the mass ratio of the color paste, preform, reactive monomer and photoinitiator is 23:50:108:3.5.

[0036] The preparation method of the modified alumina comprises the following steps:

[0037] Step 1. Alumina and absolute ethanol are added to a reaction kettle and mixed evenly, then silane coupling agent KH550 is added, and then reacted at 55 °C for 5.5 h, the solid is filtered out, rinsed 3 times with ethanol, placed in an oven and dried at 80 °C for 11 h to obtain pretreated alumina; wherein, the mass ratio of the alumina, absolute ethanol and silane coupling agent is 16:45:5.6;

[0038] Step 2. Under a nitrogen atmosphere, the pretreated alumina and absolute ethanol are mixed evenly, treated with ultrasonic power of 225 W for 12 min, an aldehyde compound is added and heated and stirred at 60 °C for 7 h, the solid is centrifuged out, rinsed 3 times with ethyl acetate, and vacuum dried at 90 °C to constant weight to obtain the product; wherein, the aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1; the mass ratio of the pretreated alumina, absolute ethanol and aldehyde compound is 6.5:25:2.4.

[0039] Example 3

[0040] A preparation method of a UV ink comprises the following steps:

[0041] S1. Under a nitrogen atmosphere, the isocyanate was heated to 60 °C at a heating rate of 10 °C / min, ethyl acetate, modified alumina, organotin catalyst and hydroquinone were added, and the mixture was stirred for 30 min. Then, the mixture was stirred at a constant temperature of 72 °C for 4 h, polyether diol was slowly added, and stirring was continued at 72 °C for 5 h. The solvent was removed by rotary evaporation to obtain a preform; the mass ratio of the isocyanate, ethyl acetate, modified alumina, organotin catalyst, hydroquinone and polyether diol was 90:60:20:0.04:0.03:30; the isocyanate used was HDI; the organotin catalyst used was dibutyltin diacetate;

[0042] S2. The color paste, preform, reaction monomer and photoinitiator were placed in a reaction kettle, stirred at 40 °C for 40 min, ground for 2.0 h and then filtered to obtain the product; wherein, the reaction monomer was composed of methacrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate in a mass ratio of 14:2.3:2.0; the mass ratio of the color paste, preform, reaction monomer and photoinitiator was 26:55:115:4.

[0043] The preparation method of the modified alumina includes the following steps:

[0044] Step 1. Alumina and absolute ethanol were added to a reaction kettle and mixed evenly, then silane coupling agent KH550 was added, and the mixture was reacted at 60 °C for 6 h. The solid was filtered, rinsed 3 times with ethanol, and placed in an oven to be dried at 80 °C for 12 h to obtain pretreated alumina; wherein, the mass ratio of the alumina, absolute ethanol and silane coupling agent was 18:50:6.2;

[0045] Step 2. Under a nitrogen atmosphere, the pretreated alumina and absolute ethanol were mixed evenly, treated with ultrasonic power of 300 W for 15 min, aldehyde compound was added, and the mixture was heated and stirred at 65 °C for 8 h. The solid was centrifuged, rinsed 3 times with ethyl acetate, and vacuum dried at 90 °C to constant weight to obtain the product; wherein, the aldehyde compound was composed of phloroglucinol and methacrolein in a mass ratio of 3:1; the mass ratio of the pretreated alumina, absolute ethanol and aldehyde compound was 7:30:2.6.

[0046] Comparative Example 1

[0047] Compared with Example 3, the difference in Comparative Example 1 was that the silane coupling agent in Step 1 of Comparative Example 1 was silane coupling agent 560, and the rest were the same.

[0048] Comparative Example 2

[0049] Compared with Example 3, the difference in Comparative Example 2 was that the aldehyde compound in Step 2 of Comparative Example 2 was methacrolein, and the rest were the same.

[0050] Comparative Example 3

[0051] Compared with Example 3, the difference in Comparative Example 3 is that the aldehyde compound in Step 2 of Comparative Example 2 is trihydroxybenzaldehyde, and the rest are the same.

[0052] Comparative Example 4

[0053] Compared with Example 3, the difference in Comparative Example 4 is that no aldehyde compound is used, and the rest are the same.

[0054] Comparative Example 5

[0055] Compared with Example 3, the difference in Comparative Example 5 is that the reaction monomer of Comparative Example 5 is ethyl methacrylate, and the rest are the same.

[0056] The UV inks of Examples 1 - 3 and Comparative Examples 1 - 5 were respectively subjected to the following performance tests, and the test results are shown in Table 1.

[0057] Hardness test: In accordance with GB / T 6739 - 2006;

[0058] Flame retardancy test: Conducted in accordance with the UL94 standard;

[0059] Adhesion test: In accordance with GB / T5210 - 2006;

[0060] Table 1

[0061]

[0062] It can be seen from the test results in Table 1 that compared with Comparative Examples 1 - 5, the flame - retardant coatings formed by the UV inks prepared in the present invention have good bonding fastness with the substrate, high flame - retardant performance, and excellent mechanical hardness.

[0063] In the present invention, the added alumina has a certain flame retardant effect, which can play a role in heat insulation and oxygen isolation. Trihydroxybenzaldehyde contains a benzene ring structure, which helps to form a carbon layer and improve the flame retardancy. Moreover, multiple hydroxyl groups on trihydroxybenzaldehyde form chemical grafting with isocyanate, increasing the structural compactness. The carbon-carbon double bond on methacrolein participates in the polymerization reaction of the reaction monomers, increasing the dispersibility of alumina in the resin system and also increasing the interfacial bonding strength between the polyurethane and the polymer formed by the reaction monomers, further increasing the mechanical strength and flame retardant performance. At the same time, while the amino-silane coupling agent changes the surface properties of alumina, the amino group it contains can release nitrogen-containing gases during combustion to dilute the combustible gases and play a flame retardant role. In addition, the modified alumina can promote carbon formation or form more crosslinked structures with the polymer matrix to delay decomposition, which may further improve the flame retardant performance; 2-Hydroxyethyl acrylate enhances the dispersibility of alumina through hydrogen bonding and reduces agglomeration; glycidyl methacrylate can form strong interfacial bonding through the chemical bonding of epoxy groups with the hydroxyl groups on the alumina surface. In addition, oxygen-containing functional groups such as hydroxyl groups and epoxy groups of the reaction monomers can further increase the binding force with polyurethane.

[0064] In summary, in the present invention, alumina is treated with an amino-silane coupling agent and then graft-modified with trihydroxybenzaldehyde and methacrolein to form an inorganic / organic composite flame retardant, which can improve the mechanical strength and flame retardant performance of the ink by introducing active hydroxyl groups, carbon-carbon double bonds to enhance interfacial bonding, increasing the crosslinking density, introducing N-containing Schiff base structures, benzene ring structures, etc.

[0065] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any indirect modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing UV ink, characterized in that: The preparation method comprises the following steps: S1. In an inert atmosphere, preheat the isocyanate, add an organic solvent, modified alumina, a catalyst and an inhibitor, mix well, stir at a constant temperature, slowly add an alcohol compound, continue stirring, and rotary evaporate to obtain a preform; S2, mixing the color paste, the preform, the reactive monomer and the photoinitiator, grinding and filtering to obtain; Wherein, the preparation method of the modified alumina comprises the following steps: Step 1: adding alumina and anhydrous ethanol into a reaction kettle and mixing them evenly, adding a silane coupling agent and heating to react, filtering, washing with alcohol, and drying to obtain pretreated alumina; Step 2: In an inert atmosphere, ultrasonically disperse the pretreated alumina and anhydrous ethanol, add an aldehyde compound, heat and stir, centrifuge, wash, and vacuum dry to obtain the product.

2. The method for preparing UV ink according to claim 1, characterized in that: In step S1, the inert atmosphere is a nitrogen atmosphere; the preheating is heating to 50-60°C at a heating rate of 5-10°C / min; the mixing is stirring and mixing for 20-30 minutes; the constant temperature stirring is constant temperature stirring at 60-72°C for 3-4 hours; and the continued stirring is continued stirring at 60-72°C for 4-5 hours.

3. The method for preparing UV ink according to claim 1, characterized in that: In step S1, the mass ratio of the isocyanate, the organic solvent, the modified alumina, the catalyst, the inhibitor and the alcohol compound is (70-90): (45-60): (15-20): (0.02-0.04): (0.02-0.03): (25-30).

4. The method for preparing UV ink according to claim 1, characterized in that: In step S1, the isocyanate is one or both of IPDI and HDI; the inhibitor is hydroquinone; and the alcohol compound is polyether diol.

5. The method for preparing UV ink according to claim 1, characterized in that: In step S2, the reaction monomer is composed of methacrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate in a mass ratio of 12-14:2.0-2.3:1.5-2.0; the mass ratio of the color paste, preform, reaction monomer and photoinitiator is (20-26):(45-55):(100-115):(3-4).

6. The method for preparing UV ink according to claim 1, characterized in that: In step S2, the stirring and mixing is performed at 30-40° C. for 30-40 min; and the grinding time is 1.5-2.0 h.

7. The method for preparing UV ink according to claim 1, characterized in that: In step 1, the mass ratio of the aluminum oxide, anhydrous ethanol and silane coupling agent is (15-18): (40-50): (5.0-6.2); the silane coupling agent is an amino-containing silane coupling agent; and the heating reaction is carried out at 50-60° C. for 5-6 hours.

8. The method for preparing UV ink according to claim 1, characterized in that: In step 2, the aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1; the mass ratio of the pretreated alumina, anhydrous ethanol and the aldehyde compound is (6-7): (20-30): (2.2-2.6).

9. The method for preparing UV ink according to claim 1, characterized in that: In step 2, the ultrasonic dispersion is carried out at an ultrasonic power of 150-300 W for 10-15 min; the heating and stirring is carried out at 55-65° C. for 6-8 h.

10. A UV ink prepared by the preparation method according to any one of claims 1 to 9.

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