A UV ink and a method for preparing the same

Abstract

This invention relates to a UV ink and its preparation method, belonging to the technical field of UV inks. The preparation method of a UV ink includes the following steps: preheating isocyanate, adding organic solvent, modified alumina, catalyst, and polymerization inhibitor, mixing thoroughly, stirring at a constant temperature, slowly adding an alcohol compound while continuing stirring, removing the solvent by rotary evaporation to obtain a preform; mixing the color paste, preform, reactive monomer, and photoinitiator, grinding, and filtering to obtain the final product. This invention uses modified alumina as a flame retardant, which is a composite of inorganic and organic flame retardants. This flame retardant has good compatibility with resins and monomers, ensuring that the UV ink coating has flame-retardant properties after curing, without affecting the coating's weather resistance and adhesion.

Description

Technical Field

[0001] This invention belongs to the technical field of UV inks, and relates to a UV ink and its preparation method. Background Technology

[0002] Recently, UV-curable inkjet inks have become increasingly popular, as they harden rapidly under ultraviolet light. These inks are suitable for a variety of materials, including soft films, leather, wallpaper, automotive stickers, acrylic, PC boards, and PVC boards, forming an ink-printed layer, leading to their growing application in the printing industry. Currently, UV-curable inkjet inks exhibit strong adhesion to materials and are resistant to fading. However, for special materials, such as UV-painted fire-retardant decorative panels, a certain level of fire resistance is required, primarily for hotel or interior decoration applications. However, most UV-painted fire-retardant decorative panels currently on the market use UV-curable inkjet inks with monomers and resins as basic components in their manufacturing process. These inks not only lack flame retardancy but also produce large amounts of harmful black smoke and irritating gases when burned.

[0003] Patent document CN115162025B discloses a digital inkjet camouflage net and its preparation method, belonging to the field of camouflage net technology. A digital inkjet camouflage net includes a base fabric and a weather-resistant ink-absorbing layer, a UV ink layer, and a protective layer sequentially coated on the base fabric. The coating for the weather-resistant ink-absorbing layer includes: waterborne polyurethane, kaolin, titanium dioxide dispersion, talc, silica, a composite flame retardant, and isocyanate. In this patent document, the composite flame retardant is obtained by mixing antimony trioxide and decabromodiphenyl ethane, then adding magnesium hydroxide or aluminum hydroxide, and stirring until homogeneous. However, antimony trioxide, magnesium hydroxide, or aluminum hydroxide have poor compatibility with waterborne coatings such as polyurethane, and when added in large proportions, they can affect the weather resistance and adhesion of the coating, thus affecting the service life of the composite material. Summary of the Invention

[0004] The purpose of this invention is to provide a UV ink and its preparation method, which can form an ink printing layer with fire-retardant properties on a substrate, while ensuring good adhesion, weather resistance and flame retardancy.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a UV ink includes the following steps:

[0007] S1. Under an inert atmosphere, the isocyanate is heated and preheated, and organic solvent, modified alumina, catalyst and polymerization inhibitor are added and mixed. The mixture is stirred at a constant temperature, and alcohol compounds are slowly added and stirred. The solvent is removed by rotary evaporation to obtain the preform.

[0008] S2. Mix the color paste, preform, reactive monomer and photoinitiator, grind and filter to obtain the final product.

[0009] As a preferred embodiment of the present invention, in step S1, the inert atmosphere is a nitrogen atmosphere; the preheating is to raise the temperature to 50-60℃ at a heating rate of 5-10℃ / 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℃ for 3-4 h; and the continued stirring is to continue stirring at 60-72℃ for 4-5 h.

[0010] As a preferred embodiment of the present invention, in step S1, the mass ratio of the isocyanate, organic solvent, modified alumina, catalyst, polymerization 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 embodiment of the present invention, in step S1, the isocyanate is one or both of IPDI and HDI; the polymerization 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 Lanxing Dongda Chemical Co., Ltd.; the organic solvent is ethyl acetate; and the catalyst is an organotin catalyst, dibutyltin diacetate.

[0012] As a preferred embodiment 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 pigment, 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, and butyl acrylate; the methacrylate used in this invention is ethyl methacrylate, the photoinitiator is photoinitiator 1173, and the pigment is Pigment Red 122.

[0013] As a preferred embodiment of the present invention, in step S2, the stirring and mixing is carried out at 30-40°C for 30-40 minutes; the grinding time is 1.5-2.0 hours.

[0014] As a preferred embodiment of the present invention, the method for preparing the modified alumina includes the following steps:

[0015] Step 1: Add alumina and anhydrous ethanol to the reaction vessel and mix well. Then add silane coupling agent, heat and react, filter, wash with alcohol, and dry to obtain pretreated alumina.

[0016] Step 2: Under an inert atmosphere, pretreated alumina and anhydrous ethanol are ultrasonically dispersed, aldehyde compounds are added, heated and stirred, centrifuged, washed, and vacuum dried to obtain the final product.

[0017] As a preferred embodiment of the present invention, in step one, the mass ratio of alumina, 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.

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

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

[0020] As a preferred embodiment of the present invention, in step two, the inert atmosphere is a nitrogen atmosphere; the ultrasonic dispersion is performed by ultrasonic power of 150-300W for 10-15 minutes; the heating and stirring is performed by heating and stirring at 55-65℃ for 6-8 hours; the washing is performed by rinsing with ethyl acetate 3 times; and the vacuum drying is performed by vacuum drying at 90℃ to constant weight.

[0021] The beneficial effects of this invention are:

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

[0023] In addition, when printing with the UV ink of the present invention, an ink printing layer with flame-retardant properties can be formed on special materials such as UV-painted fireproof decorative panels. This printing layer not only has excellent fire resistance, but also ensures good adhesion and weather resistance, thereby improving the performance and service life of the UV-painted fireproof decorative panels. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0025] Example 1

[0026] A method for preparing a UV ink includes the following steps:

[0027] S1. Under a nitrogen atmosphere, 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, the mixture is stirred at a constant temperature of 60°C for 3 h. Polyether glycol is slowly added and the mixture is stirred at 60°C for another 4 h. The solvent is removed by rotary evaporation to obtain the preform. The mass ratio of isocyanate, ethyl acetate, modified alumina, organotin catalyst, hydroquinone, and polyether glycol is 70:45:15:0.02:0.02:25. The isocyanate used is HDI. The organotin catalyst used is dibutyltin diacetate.

[0028] S2. Place the color paste, preform, reactive monomer, and photoinitiator in a reaction vessel, stir at 30°C for 30 min, grind for 1.5 h, and then filter to obtain the final product; wherein the reactive monomer is composed of methacrylate, 2-hydroxyethyl acrylate, and glycidyl methacrylate in a mass ratio of 12:2.0:1.5; and the mass ratio of the color paste, preform, reactive monomer, and photoinitiator is 20:45:100:3.

[0029] The method for preparing the modified alumina includes the following steps:

[0030] Step 1: Add alumina and anhydrous ethanol to a reaction vessel and mix well. Then add silane coupling agent KH550 and react at 50°C for 5 hours. Filter to obtain the solid, wash it three times with ethanol, and dry it in an oven at 80°C for 10 hours to obtain pretreated alumina. The mass ratio of alumina, anhydrous ethanol and silane coupling agent is 15:40:5.0.

[0031] Step 2: Under a nitrogen atmosphere, pretreated alumina and anhydrous ethanol are mixed and treated with ultrasonic power at 150W for 10 minutes. An aldehyde compound is added and heated and stirred at 55℃ for 6 hours. The solid is collected by centrifugation, washed three times with ethyl acetate, and dried under vacuum at 90℃ to constant weight to obtain the final product. The aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1. The mass ratio of pretreated alumina, anhydrous ethanol, and the aldehyde compound is 6:20:2.2.

[0032] Example 2

[0033] A method for preparing a UV ink includes the following steps:

[0034] S1. Under a nitrogen atmosphere, 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, the mixture is stirred at a constant temperature of 65°C for 3.5 h. Polyether glycol is slowly added and the mixture is stirred at 65°C for another 4.5 h. The solvent is removed by rotary evaporation to obtain the preform. The mass ratio of isocyanate, ethyl acetate, modified alumina, organotin catalyst, hydroquinone, and polyether glycol is 80:52:18:0.03:0.025:28. The isocyanate used is HDI. The organotin catalyst used is dibutyltin diacetate.

[0035] S2. Place the color paste, preform, reactive monomer, and photoinitiator in a reaction vessel, stir at 35°C for 35 min, grind for 1.8 h, and then filter to obtain the final 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 method for preparing the modified alumina includes the following steps:

[0037] Step 1: Add alumina and anhydrous ethanol to a reaction vessel and mix well. Then add silane coupling agent KH550 and react at 55°C for 5.5 hours. Filter to obtain the solid, wash three times with ethanol, and dry in an oven at 80°C for 11 hours to obtain pretreated alumina. The mass ratio of alumina, anhydrous ethanol, and silane coupling agent is 16:45:5.6.

[0038] Step 2: Under a nitrogen atmosphere, pretreated alumina and anhydrous ethanol are mixed and treated with ultrasonic power at 225W for 12 minutes. An aldehyde compound is added and heated and stirred at 60℃ for 7 hours. The solid is collected by centrifugation, washed three times with ethyl acetate, and dried under vacuum at 90℃ to constant weight to obtain the final product. The aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1. The mass ratio of pretreated alumina, anhydrous ethanol, and the aldehyde compound is 6.5:25:2.4.

[0039] Example 3

[0040] A method for preparing a UV ink includes the following steps:

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

[0042] S2. Place the color paste, preform, reactive monomer, and photoinitiator in a reaction vessel, stir at 40°C for 40 min, grind for 2.0 h, and then filter to obtain the final product; wherein the reactive monomer is composed of methacrylate, 2-hydroxyethyl acrylate, and glycidyl methacrylate in a mass ratio of 14:2.3:2.0; and the mass ratio of the color paste, preform, reactive monomer, and photoinitiator is 26:55:115:4.

[0043] The method for preparing the modified alumina includes the following steps:

[0044] Step 1: Add alumina and anhydrous ethanol to a reaction vessel and mix well. Then add silane coupling agent KH550 and react at 60°C for 6 hours. Filter to obtain the solid, wash it three times with ethanol, and dry it in an oven at 80°C for 12 hours to obtain pretreated alumina. The mass ratio of alumina, anhydrous ethanol and silane coupling agent is 18:50:6.2.

[0045] Step 2: Under a nitrogen atmosphere, pretreated alumina and anhydrous ethanol are mixed and treated with ultrasonic power at 300W for 15 minutes. An aldehyde compound is added and heated and stirred at 65℃ for 8 hours. The solid is collected by centrifugation, washed three times with ethyl acetate, and dried under vacuum at 90℃ to constant weight to obtain the final product. The aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:1. The mass ratio of pretreated alumina, anhydrous ethanol, and the aldehyde compound is 7:30:2.6.

[0046] Comparative Example 1

[0047] Compared with Example 3, Comparative Example 1 differs in that the silane coupling agent in step one of Comparative Example 1 is silane coupling agent 560, while the rest are the same.

[0048] Comparative Example 2

[0049] Compared with Example 3, Comparative Example 2 differs in that the aldehyde compound in step two of Comparative Example 2 is methacrolein, while the rest are the same.

[0050] Comparative Example 3

[0051] Compared with Example 3, Comparative Example 3 differs in that the aldehyde compound in step two of Comparative Example 2 is trihydroxybenzaldehyde, while the rest are the same.

[0052] Comparative Example 4

[0053] Compared with Example 3, Comparative Example 4 differs in that it does not use aldehyde compounds, but is otherwise identical.

[0054] Comparative Example 5

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

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

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

[0058] Flame retardancy test: conducted according to UL94 standard;

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

[0060] Table 1

[0061]

[0062] As can be seen from the test results in Table 1, compared with Comparative Examples 1-5, the flame-retardant coating formed by the UV ink prepared in this invention has good bonding strength with the substrate, high flame-retardant performance, and excellent mechanical hardness.

[0063] This invention utilizes alumina, which possesses a certain flame-retardant effect and can serve as heat insulation and oxygen barrier. Trihydroxybenzaldehyde contains a benzene ring structure, which helps to form a char layer and improves flame retardancy. Furthermore, the multiple hydroxyl groups on trihydroxybenzaldehyde form chemical grafts with isocyanates, increasing structural density. The carbon-carbon double bonds on methacrolein participate in the polymerization reaction of the reactants, 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 reactants, further enhancing mechanical strength and flame-retardant properties. Simultaneously, while the aminosilane coupling agent alters the surface properties of alumina, the amino groups it contains can release nitrogen-containing gases during combustion, diluting flammable gases and thus playing a flame-retardant role. In addition, the modified alumina can promote char formation or form more cross-linked structures with the polymer matrix, delaying decomposition and potentially further improving flame retardant properties; 2-hydroxyethyl acrylate enhances the dispersibility of alumina through hydrogen bonding and reduces agglomeration; glycidyl methacrylate can chemically bond with the hydroxyl groups on the surface of alumina through epoxy groups, forming a strong interfacial bond. Furthermore, the oxygen-containing functional groups such as hydroxyl and epoxy groups of the reactants can further increase the bonding force with polyurethane.

[0064] In summary, this invention treats alumina with an aminosilane coupling agent and then grafts it with trihydroxybenzaldehyde and methacrolein to form an inorganic / organic composite flame retardant. This flame retardant can improve the mechanical strength and flame retardant properties of ink by introducing active hydroxyl groups, carbon-carbon double bonds to enhance interfacial bonding, increasing crosslinking density, introducing N-containing Schiff base structures, and benzene ring structures.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a UV ink, characterized by, The preparation method comprises the following steps: S1, under inert atmosphere, preheat the isocyanate, add organic solvent, modified alumina, catalyst and polymerization inhibitor, mix uniformly, constant temperature stirring, slowly add alcohol compound and continue to stir, rotary evaporation, to get the preform; S2, the color paste, preform, reaction monomer and photoinitiator are stirred and mixed, ground and filtered, to obtain the UV ink; the reaction monomer is composed of methyl methacrylate, 2-hydroxyethyl acrylate and glycidyl methacrylate in a mass ratio of 12-14:2.0-2.3:1.5-2.0; The preparation method of the modified alumina comprises the following steps: Step one, after mixing alumina and anhydrous ethanol in the reaction kettle, add silane coupling agent and heat to react, filter, alcohol wash, dry, to get pretreated alumina; the silane coupling agent is amino-containing silane coupling agent; Step two, under inert atmosphere, ultrasonic dispersion of pretreated alumina and anhydrous ethanol, add aldehyde compound and heat stirring, centrifugal, washing, vacuum drying, to obtain; the aldehyde compound is composed of trihydroxybenzaldehyde and methacrolein in a mass ratio of 3:

1.

2. The method of claim 1, wherein: In step S1, the inert atmosphere is nitrogen atmosphere; the preheating is heated to 50-60℃ at a heating rate of 5-10℃ / min; the mixing is uniformly stirred for 20-30min; the constant temperature stirring is constant temperature stirring at 60-72℃ for 3-4h; the continue stirring is continue stirring at 60-72℃ for 4-5h.

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

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

5. The method for preparing a UV ink according to claim 1, characterized in that: In step S2, the mass ratio of the color paste, preform, reaction monomer and photoinitiator is (20-26):(45-55):(100-115):(3-4).

6. The method of claim 1, wherein: In step S2, the stirring mixing is stirring at 30-40℃ for 30-40min; the grinding time is 1.5-2.0h.

7. The method for preparing a UV ink according to claim 1, characterized in that: In step one, the mass ratio of the alumina, anhydrous ethanol and silane coupling agent is (15-18):(40-50):(5.0-6.2); the heating reaction is reacted at 50-60℃ for 5-6h.

8. The method of claim 1, wherein: In step two, the mass ratio of the pretreated alumina, anhydrous ethanol and aldehyde compound is (6-7):(20-30):(2.2-2.6).

9. The method for preparing a UV ink according to claim 1, characterized in that: In step two, the ultrasonic dispersion is treated at 150-300W ultrasonic power for 10-15min; the heating stirring is heated and stirred at 55-65℃ for 6-8h.

10. The UV ink prepared by the preparation method of any one of claims 1-9.

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