Offset printing UV printing ink and printing method

Abstract

The invention discloses offset printing UV printing ink and a printing method, and belongs to the technical field of ink preparation, the offset printing UV printing ink comprises the following components by weight: 30-50 parts of polyester acrylate resin, 10-30 parts of an acrylate monomer, 1-10 parts of a cross-linking agent, 1-10 parts of an initiator, 5-30 parts of a pigment filler, and 4-12 parts of an auxiliary agent; the cross-linking agent is prepared by taking caprolactone acrylate as a raw material, carrying out ring opening polymerization on the caprolactone acrylate and 1, 4-benzenedimethanol, and grafting an acryloyl group at a terminal group through acyl chloride; by introducing the cross-linking agent, the curing speed of the ink is effectively increased.

Description

Technical Field

[0001] The invention relates to the technical field of ink preparation, and in particular to an offset UV printing ink and a printing method. Background Art

[0002] UV offset ink is a high-performance printing material based on ultraviolet light curing technology. Its core principle is to cure the ink by initiating a luminescent chemical reaction through ultraviolet light. The composition of UV offset ink usually includes photoinitiators, active resins (such as acrylates), monomers, pigments and additives. When the printed ink is exposed to UV light of a specific wavelength (usually 200-400nm), the photoinitiator absorbs light energy and decomposes to produce active free radicals or cations, which in turn triggers a polymerization reaction between the resin and the monomer to form a cross-linked structure, and finally solidifies the liquid ink to form an ink layer. This process does not require the oxidation or penetration drying time of traditional inks, which significantly improves printing efficiency, and the cured ink layer has high gloss, wear resistance and chemical resistance. UV offset ink is widely used in many fields due to its unique properties.

[0003] Traditional offset UV printing inks mostly use unsaturated polyester and acrylate resins as film-forming resins, but these resins have limited drying speeds, and their internal curing speeds are far slower than those on the surface, making it difficult to meet the requirements of high-speed printing. Summary of the invention

[0004] In view of the above problems, the present invention provides an offset UV printing ink and a printing method.

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

[0006] An offset UV printing ink, comprising the following components by weight: 30-50 parts of polyester acrylate resin, 10-30 parts of acrylate monomer, 1-10 parts of crosslinking agent, 1-10 parts of initiator, 5-30 parts of color filler, and 4-12 parts of auxiliary agent;

[0007] The preparation method of the cross-linking agent comprises the following steps:

[0008] (1) Weigh caprolactone acrylate and 1,4-benzenedimethanol respectively and mix them, add glycidol, add diphenyl phosphate as a catalyst, and react at 20-40° C. under a protective atmosphere with stirring for 0.1-1 h. After the reaction is completed, add triethylamine to terminate the reaction, add to cold ether for precipitation, dissolve the precipitate in tetrahydrofuran, add to cold ether for precipitation again, and dry to obtain an intermediate product;

[0009] (2) Dissolve the intermediate product in tetrahydrofuran, add triethylamine, slowly dropwise add methacryloyl chloride under a protective atmosphere. After the dropping is completed, stir and react at room temperature under a protective atmosphere for 20 - 24 h. After the reaction is completed, remove the precipitate. Add the supernatant to cold ether for precipitation. The precipitate is dissolved in tetrahydrofuran and then added to cold ether for precipitation again. After drying, it is obtained.

[0010] In some preferred embodiments, the polyester acrylate resin is one or more of a tetrafunctional aliphatic polyester acrylate resin, a hexafunctional aliphatic polyester acrylate resin, and an octafunctional aliphatic polyester acrylate resin.

[0011] In some preferred embodiments, the acrylate monomer is one or more of isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethoxydiethoxyethyl acrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, and triethylene glycol diacrylate.

[0012] In some preferred embodiments, the initiator is one or more of 1-hydroxy-cyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-phenylpropan-1-one, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide, and 2-hydroxy-2-methyl-p-hydroxyethyl ether phenylpropan-1-one.

[0013] In some preferred embodiments, the pigment and filler include pigments and fillers, and the filler is one or more of matte powder, talc powder, and calcium carbonate.

[0014] In some preferred embodiments, the additives are one or more of wax paste, matting agent, dispersant, leveling agent, and defoaming agent.

[0015] In some preferred embodiments, in step (1), the mass ratio of the caprolactone acrylate to the 1,4-benzenedimethanol, the glycidyl, and the diphenyl phosphate is 12:(0.1 - 0.2):(0.24 - 0.34):(1.8 - 2.3).

[0016] In some preferred embodiments, in step (2), the mass ratio of the intermediate product to the triethylamine and the methacryloyl chloride is 10:(0.72 - 0.9):(0.5 - 0.68).

[0017] In some preferred embodiments, the acrylate monomer includes a coumarin-modified monomer, and its preparation method includes the following steps:

[0018] Weigh 7-hydroxy-4-methylcoumarin and dissolve it in dimethylformamide. Add potassium carbonate and mix well. Then add 2-bromoethanol. Keep stirring and reacting at 80-90 °C under a protective atmosphere for 12-20 h. After the reaction is completed, cool it down, precipitate it in ice water, separate the precipitate and dry it under vacuum to obtain product A. Weigh the obtained product A and dissolve it in chloroform. Add triethylamine and mix well. Then add methacryloyl chloride under a protective atmosphere and stir and react for 6-12 h. After the reaction is completed, dilute it with dichloromethane, wash it with saturated brine, dry it and then evaporate the solvent to obtain the product.

[0019] In some preferred embodiments, the mass ratio of 7-hydroxy-4-methylcoumarin, potassium carbonate and 2-bromoethanol is 10:(15-19):(5.5-7); the mass ratio of product A, triethylamine and methacryloyl chloride is 10:(17-22):(11-14).

[0020] In some preferred embodiments, the molar ratio of the coumarin-modified monomer in the acrylate monomer is 10-30%.

[0021] The second aspect of the present invention is to provide a printing method for the offset UV printing ink, which includes the following steps:

[0022] S1. Weigh each raw material in proportion and set it aside for use.

[0023] S2. Mix the polyester acrylate resin, the acrylate monomer, the crosslinking agent, the initiator and the auxiliary agent, stir well until completely dissolved, then add the pigment filler, continue to stir until evenly dispersed, and grind it in a grinding machine to a desired fineness to obtain the offset UV printing ink.

[0024] S3. Print the offset UV printing ink on the printed matter, and then dry and cure it with a UV lamp; the printed matter is one or several of metal foil paper, synthetic paper, composite gold and silver cardboard, composite laser paper, transfer paper, polyvinyl chloride sheet, polyester sheet, polypropylene sheet, polyethylene sheet.

[0025] The beneficial effects of the present invention are as follows:

[0026] In view of the problem that the drying speed of offset UV printing inks in the prior art is limited, the internal curing speed is far lower than the surface curing speed, and it is difficult to meet the requirements of high-speed printing, the present invention provides an offset UV printing ink. The ink uses polyester acrylate and acrylate as film-forming resins, and the curing speed of the ink is increased by introducing a crosslinking agent. Specifically, the present invention uses caprolactone acrylate as a raw material, 1,4-benzenedimethanol as a diol for ring-opening polymerization, and then grafts an acyl chloride to the terminal acryloyl group to prepare a branched polycaprolactone structure containing terminal carboxyl groups and terminal acryloyl groups. As a film-forming resin crosslinking agent, it effectively improves the curing rate of the ink and also promotes the stability of the ink. Further, the present invention also further improves the curing efficiency of the ink by introducing coumarin-modified acrylate monomers. Specifically, the present invention uses 7-hydroxy-4-methylcoumarin as a raw material, and connects the coumarin group and the acrylate group through acyl chloride grafting in the active monomer of the ink to introduce the coumarin group, and utilizes its sensitivity to ultraviolet light and high absorption to enhance the absorption efficiency of the curing ultraviolet light by the ink and further accelerate the curing speed. Detailed Embodiments

[0027] The present invention will be further described in conjunction with the following embodiments.

[0028] Example 1

[0029] An offset UV printing ink, by weight, comprises the following components: 45 parts of polyester acrylate resin, 19 parts of acrylate monomer, 6.4 parts of crosslinking agent, 3.5 parts of initiator, 6 parts of pigment, 11 parts of filler, 3.5 parts of wax paste, 1 part of dispersant, and 0.45 part of defoamer;

[0030] The preparation method of the crosslinking agent comprises the following steps:

[0031] (1) Weigh caprolactone acrylate (CAS No. 110489-05-9) and 1,4-benzenedimethanol respectively and mix them, add glycidyl, add diphenyl phosphate as a catalyst, keep stirring and reacting at 35 °C under a protective atmosphere for 0.5 h. After the reaction is completed, add triethylamine to terminate the reaction, precipitate in cold ether, dissolve the precipitate in tetrahydrofuran and then add it to cold ether again for precipitation, and dry to obtain an intermediate product; the mass ratio of the caprolactone acrylate to the 1,4-benzenedimethanol, the glycidyl, and the diphenyl phosphate is 12:0.14:0.3:2.03;

[0032] (2) Dissolve the intermediate product in tetrahydrofuran, add triethylamine, and slowly dropwise add methacryloyl chloride under a protective atmosphere. After the addition is complete, stir and react at room temperature under a protective atmosphere for 22 h. After the reaction is complete, remove the precipitate. Add the supernatant to cold ether for precipitation. Dissolve the precipitate in tetrahydrofuran and then add it to cold ether again for precipitation. After drying, it is obtained; the mass ratio of the intermediate product, the triethylamine, and the methacryloyl chloride is 10:0.8:0.6;

[0033] The polyester acrylate resin is pentaerythritol tetraacrylate;

[0034] The acrylate monomer is a mixture of isobornyl methacrylate and 1,6-hexanediol diacrylate in an equimolar ratio;

[0035] The initiator is 2-hydroxy-2-methyl-phenylacetone-1 (1173);

[0036] The pigment is carbon black; the filler is calcium carbonate;

[0037] The dispersant is dispersant 5040; the defoamer is defoamer byk-028;

[0038] The preparation method of the offset printing UV printing ink comprises the following steps:

[0039] S1. Weigh each raw material in proportion for standby;

[0040] S2. Mix the polyester acrylate resin, the acrylate monomer, the crosslinking agent, the initiator, and the additives, stir well until completely dissolved, then add the pigment and filler, continue to stir until evenly dispersed, and grind in a grinding machine to a desired fineness to obtain the offset printing UV printing ink.

[0041] Example 2

[0042] An offset printing UV printing ink, by weight, comprises the following components: 45 parts of polyester acrylate resin, 19 parts of acrylate monomer, 6.4 parts of crosslinking agent, 3.5 parts of initiator, 6 parts of pigment, 11 parts of filler, 3.5 parts of wax paste, 1 part of dispersant, and 0.45 part of defoamer;

[0043] The preparation method of the crosslinking agent comprises the following steps:

[0044] (1) Weigh ε-caprolactone acrylate (CAS No. 110489-05-9) and 1,4-benzenedimethanol separately and mix them. Add glycidyl alcohol, and add diphenyl phosphate as a catalyst. Keep stirring and reacting at 35 °C under a protective atmosphere for 0.5 h. After the reaction is completed, add triethylamine to terminate the reaction, and precipitate in cold ether. The precipitate is dissolved in tetrahydrofuran and then added to cold ether again for precipitation. After drying, an intermediate product is obtained; the mass ratio of the ε-caprolactone acrylate, the 1,4-benzenedimethanol, the glycidyl alcohol, and the diphenyl phosphate is 12:0.14:0.3:2.03;

[0045] (2) Dissolve the intermediate product in tetrahydrofuran, add triethylamine, and slowly dropwise add methacryloyl chloride under a protective atmosphere. After the dropping is completed, stir and react at room temperature under a protective atmosphere for 22 h. After the reaction is completed, remove the precipitate, and add the supernatant to cold ether for precipitation. The precipitate is dissolved in tetrahydrofuran and then added to cold ether again for precipitation. After drying, it is obtained; the mass ratio of the intermediate product, the triethylamine, and the methacryloyl chloride is 10:0.8:0.6;

[0046] The polyester acrylate resin is pentaerythritol tetraacrylate;

[0047] The acrylate monomer is a mixture of isobornyl methacrylate, 1,6-hexanediol diacrylate, and a coumarin-modified monomer with a molar ratio of 2:2:1;

[0048] The preparation method of the coumarin-modified monomer includes the following steps:

[0049] Weigh 7-hydroxy-4-methylcoumarin and dissolve it in dimethylformamide. Add potassium carbonate and mix. Add 2-bromoethanol, and keep stirring and reacting at 85 °C under a protective atmosphere for 15 h. After the reaction is completed, cool it, precipitate in ice water, separate the precipitate and dry it under vacuum to obtain product A; weigh product A and dissolve it in chloroform, add triethylamine and mix. Add methacryloyl chloride under a protective atmosphere and stir and react for 8 h. After the reaction is completed, dilute it with dichloromethane, wash it with saturated brine, and dry it and then evaporate the solvent to obtain it; the mass ratio of the 7-hydroxy-4-methylcoumarin, the potassium carbonate, and the 2-bromoethanol is 4:6.23:2.5; the mass ratio of product A, the triethylamine, and the methacryloyl chloride is 4:8:4.5;

[0050] The initiator is 2-hydroxy-2-methyl-1-phenylpropan-1-one (1173);

[0051] The pigment is carbon black; the filler is calcium carbonate;

[0052] The dispersant is dispersant 5040; the defoamer is defoamer byk-028;

[0053] The preparation method of the offset UV printing ink is the same as that in Example 1.

[0054] Example 3

[0055] An offset UV printing ink, by weight, comprises the following components: 45 parts of polyester acrylate resin, 19 parts of acrylate monomer, 3.5 parts of initiator, 6 parts of pigment, 11 parts of filler, 3.5 parts of wax paste, 1 part of dispersant, and 0.45 part of defoamer;

[0056] The polyester acrylate resin is pentaerythritol tetraacrylate;

[0057] The acrylate monomer is a mixture of isobornyl methacrylate, 1,6 - hexanediol diacrylate and coumarin - modified monomer with a molar ratio of 2:2:1;

[0058] The preparation method of the coumarin - modified monomer comprises the following steps:

[0059] Weigh 7 - hydroxy - 4 - methylcoumarin and dissolve it in dimethylformamide, add potassium carbonate and mix, then add 2 - bromoethanol, keep stirring and reacting at 85 °C under a protective atmosphere for 15 h. After the reaction is completed, cool it, precipitate it in ice water, separate the precipitate and dry it under vacuum to obtain product A; weigh the product A and dissolve it in chloroform, add triethylamine and mix, add methacryloyl chloride under a protective atmosphere, stir and react for 8 h. After the reaction is completed, dilute it with dichloromethane, wash it with saturated brine, dry it and evaporate the solvent to obtain it; the mass ratio of 7 - hydroxy - 4 - methylcoumarin to potassium carbonate and 2 - bromoethanol is 4:6.23:2.5; the mass ratio of product A to triethylamine and methacryloyl chloride is 4:8:4.5;

[0060] The initiator is 2 - hydroxy - 2 - methyl - phenylpropan - 1 - one (1173);

[0061] The pigment is carbon black; the filler is calcium carbonate;

[0062] The dispersant is dispersant 5040; the defoamer is defoamer byk - 028;

[0063] The preparation method of the offset UV printing ink is the same as that in Example 1.

[0064] Example 4

[0065] An offset UV printing ink, by weight, comprises the following components: 45 parts of polyester acrylate resin, 19 parts of acrylate monomer, 3.5 parts of initiator, 6 parts of pigment, 11 parts of filler, 3.5 parts of wax paste, 1 part of dispersant, and 0.45 part of defoamer;

[0066] The polyester acrylate resin is pentaerythritol tetraacrylate;

[0067] The acrylate monomer is a mixture of isobornyl methacrylate and 1,6 - hexanediol diacrylate in an equimolar ratio;

[0068] The initiator is 2 - hydroxy - 2 - methyl - phenylacetone - 1 (1173);

[0069] The pigment is carbon black; the filler is calcium carbonate;

[0070] The dispersant is dispersant 5040; the defoamer is defoamer byk - 028;

[0071] The preparation method of the offset printing UV ink is the same as that in Example 1.

[0072] The properties of the offset printing UV inks described in Examples 1 - 4 were tested. Among them, the adhesion was tested by the industry's adhesion method, and whether the adhesion was qualified was determined according to the size of the peel strength value and the failure type. 10 points (the ink film cannot be peeled off) is the highest, and 0 points (the ink film peeling is greater than 80%) is the lowest; the viscosity, drying property, and fluidity refer to the industry standard QB / T 2826 - 2017. Among them, the drying property was judged according to the scratch situation at the tail of the paper clip after the first drying. 10 points (fully cured) is the highest, and 0 points (cannot be cured) is the lowest; the stability was tested by subjecting the ink to 30 repeated freeze (at - 20°C) and heat (at 75°C) tests, observing whether there was gelation or reverse coarsening of the ink, and then scoring according to the ink situation. 10 points (almost no change) is the highest, and 0 points (extremely poor stability) is the lowest; the measurement results are as follows:

[0073] Adhesion / minute Viscosity Drying property / minute Flowability / mm Stability / minute Example 1 9 12 9 30 9 Example 2 10 13 10 28 9 Example 3 8 13 9 28 7 Example 4 7 12 6 31 4

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An offset UV printing ink, characterized in that: The composition includes the following components by weight: 30-50 parts of polyester acrylate resin, 10-30 parts of acrylate monomer, 1-10 parts of crosslinking agent, 1-10 parts of initiator, 5-30 parts of pigment and filler, and 4-12 parts of auxiliary agent; The preparation method of the cross-linking agent comprises the following steps: (1) Weigh caprolactone acrylate and 1,4-benzenedimethanol respectively and mix them, add glycidol, add diphenyl phosphate as a catalyst, and react at 20-40° C. under a protective atmosphere with stirring for 0.1-1 h. After the reaction is completed, add triethylamine to terminate the reaction, add to cold ether for precipitation, dissolve the precipitate in tetrahydrofuran, add to cold ether for precipitation again, and dry to obtain an intermediate product; (2) The intermediate product is dissolved in tetrahydrofuran, triethylamine is added, and methacryloyl chloride is slowly added dropwise under a protective atmosphere. After the addition is completed, the mixture is stirred and reacted for 20-24 hours at room temperature and in a protective atmosphere. After the reaction is completed, the precipitate is removed, and the supernatant is added to cold ether for precipitation. The precipitate is dissolved in tetrahydrofuran and then added to cold ether for precipitation again, and dried to obtain the product.

2. An offset UV printing ink according to claim 1, characterized in that: The polyester acrylic resin is one or more of a tetrafunctional aliphatic polyester acrylic resin, a hexafunctional aliphatic polyester acrylic resin and an octafunctional aliphatic polyester acrylic resin.

3. An offset UV printing ink according to claim 1, characterized in that: The acrylate monomer is one or more of isobornyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, ethoxyethoxyethyl acrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, and triethylene glycol diacrylate.

4. The offset UV printing ink according to claim 1, characterized in that: The initiator is one or more of 1-hydroxy-cyclohexyl benzophenone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-hydroxy-2-methyl-phenylacetone-1, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide, and 2-hydroxy-2-methyl-p-hydroxyethyl ether phenylacetone-1.

5. The offset UV printing ink according to claim 1, characterized in that: The auxiliary agent is one or more of wax slurry, matting agent, dispersant, leveling agent and defoaming agent.

6. An offset UV printing ink according to claim 1, characterized in that: In step (1), the mass ratio of the caprolactone acrylate to the 1,4-benzenedimethanol, the glycidol, and the diphenyl phosphate is 12:(0.1-0.2):(0.24-0.34):(1.8-2.3).

7. An offset UV printing ink according to claim 1, characterized in that: The mass ratio of the intermediate product to the triethylamine and the methacryloyl chloride in step (2) is 10:(0.72-0.9):(0.5-0.68).

8. The offset UV printing ink according to claim 1, characterized in that: The acrylate monomer includes a coumarin-modified monomer, and the preparation method thereof includes the following steps: Weigh 7-hydroxy-4-methylcoumarin and dissolve it in dimethylformamide, add potassium carbonate and mix, add 2-bromoethanol, keep warm and stir for 12-20 hours under a protective atmosphere at 80-90°C, cool after the reaction is completed, add ice water to precipitate, separate the precipitate and vacuum dry to obtain product A; weigh the product A and dissolve it in chloroform, add triethylamine and mix, add methacryloyl chloride under a protective atmosphere, stir for 6-12 hours, add dichloromethane to dilute after the reaction is completed, wash with saturated brine, dry and evaporate the solvent to obtain the product.

9. An offset UV printing ink according to claim 8, characterized in that: The mass ratio of the 7-hydroxy-4-methylcoumarin to the potassium carbonate and the 2-bromoethanol is 10:(15-19):(5.5-7); the mass ratio of the product A to the triethylamine and the methacryloyl chloride is 10:(17-22):(11-14).

10. A printing method of offset UV printing ink according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh each raw material in proportion and set aside; S2, mixing the polyester acrylate resin, the acrylate monomer, the crosslinking agent, the initiator and the auxiliary agent, stirring them fully until they are completely dissolved, adding the pigment and filler, continuing to stir until they are evenly dispersed, and grinding them into a grinder to a desired fineness to obtain the offset UV printing ink; S3, printing the offset UV printing ink onto a printed piece, and then drying and curing it with a UV lamp; The printing piece is one or more of metal foil paper, synthetic paper, composite gold and silver card paper, composite laser paper, transfer paper, polyvinyl chloride sheet, polyester sheet, polypropylene sheet, and polyethylene sheet.