Intaglio printing ink composition and intaglio printing method

Abstract

The invention discloses an intaglio printing ink composition and an intaglio printing method, and belongs to the technical field of ink preparation, the intaglio printing ink composition comprises the following components by weight: 40-80 parts of a polyacrylic acid emulsion and / or a polyacrylate emulsion, 5-15 parts of a hydroxyl acrylate monomer, 4-12 parts of a cross-linking agent, and 5-15 parts of a low alcohol solvent, 8-26 parts of pigment filler, 1-8 parts of an initiator and 3-10 parts of an auxiliary agent; the cross-linking agent is formed by taking pentaerythritol as a matrix, preparing pentaerythritol ester containing bromo-isobutyl through acylation reaction ester formation, and then polymerizing with tert-butyl acrylate through atom transfer radical polymerization reaction. By introducing the cross-linking agent, the curing speed of the resin binder is increased, and meanwhile, the adhesive force and the stability of the ink are improved.

Description

Technical Field

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

[0002] Gravure printing is widely used in the food, medicine and tobacco packaging industries, and is closely related to people's lives and health. A large amount of volatile organic solvents are used in traditional gravure printing inks, which not only pollute the environment, but also the residual organic solvents in the printed products are harmful to human health. With the increasingly rapid development of human civilization, sustainable development and green environmental protection have become social trends. The development and application of water-based inks can greatly improve the printing operation environment and enhance product quality and safety, and thus have attracted the attention and favor of the packaging and printing industry. The curing principle of water-based gravure inks is based on photopolymerization reactions initiated by ultraviolet light. The main components of inks include photoinitiators, active resins (such as acrylates), monomers, pigments and additives. During the printing process, after the cells of the gravure cylinder are filled with ink, the excess ink on the surface is scraped off by a scraper, leaving only the ink in the cells, which is then transferred to the surface of the substrate under pressure. At this time, the ink has not yet solidified and is still in liquid state. When the printed material passes through an ultraviolet light irradiation device (UV lamp), the photoinitiator absorbs ultraviolet light energy of a specific wavelength (usually 200-400nm), decomposes to produce active free radicals or cations, triggering a chain polymerization reaction between the resin and the monomer to form a three-dimensional network structure, thereby completing the curing.

[0003] Acrylate emulsion is a commonly used film-forming agent for gravure printing UV ink and is widely used in water-based gravure ink. However, its internal curing speed is far slower than that of the surface, and it generally faces problems such as slow drying and poor adhesion. Summary of the invention

[0004] In view of the above problems, the present invention provides a gravure printing ink composition and a gravure printing method.

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

[0006] A gravure printing ink composition, comprising the following components by weight: 40-80 parts of polyacrylic acid emulsion and / or polyacrylate emulsion, 5-15 parts of hydroxy acrylate monomer, 4-12 parts of crosslinking agent, 5-15 parts of low-grade alcohol solvent, 8-26 parts of pigment filler, 1-8 parts of initiator, and 3-10 parts of auxiliary agent;

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

[0008] (1) Weigh pentaerythritol and dissolve it in a tetrahydrofuran solvent. Add triethanolamine, and after fully stirring and mixing, add 2-bromoisobutyryl bromide under a protective atmosphere and an ice-water bath. After stirring and mixing again, stir and react at room temperature for 12 - 20 h. After the reaction is completed, add dichloromethane to dilute the reaction system, and then wash it successively with an acidic solution, a basic solution, and deionized water. The organic phase is dried and then the solvent is evaporated. Recrystallize and purify with methanol, and vacuum dry to obtain the intermediate product;

[0009] (2) Dissolve the intermediate product in a dimethylformamide solvent, add copper bromide, pentamethyldiethylenetriamine, and tert-butyl acrylate. Under a protective atmosphere, heat to 60 - 90 °C and stir and react for 0.1 - 1 h. After the reaction is completed, quickly cool with an ice-water bath, pass through an alkaline alumina column to remove the catalyst, add a cold methanol aqueous solution, fully stir and then separate the precipitate, and vacuum dry to obtain it.

[0010] In some preferred embodiments, the polymerization molecular weight of the polyacrylic acid emulsion and the polyacrylate emulsion is 100,000 - 150,000, the pH value is 6 - 8, and the solid content is 35 - 45%.

[0011] In some preferred embodiments, the hydroxyacrylate monomer is one or more of 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, and β-hydroxypropyl methacrylate.

[0012] In some preferred embodiments, the initiator is one or more of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, potassium persulfate, tert-butyl hydroperoxide, ammonium persulfate, ferrous salt, cumene hydroperoxide, sodium bisulfite, and sodium thiosulfate.

[0013] In some preferred embodiments, the lower alcohol solvent is an alcohol solvent with 1 - 5 carbon atoms.

[0014] In some preferred embodiments, the pigment and filler include pigments and fillers. The pigment is one or more of phthalocyanine pigments, carbon black, and titanium white; the filler is one or more of matting powder, talc powder, calcium carbonate, and silicon dioxide.

[0015] In some preferred embodiments, the auxiliary agent is one or more of a dispersant, an emulsifier, a stabilizer, a softener, a preservative, an antifoaming agent, a pH regulator, an adhesion promoter, an antistatic agent, a thickener, and a light absorber.

[0016] In some preferred embodiments, in step (1), the mass ratio of pentaerythritol to triethanolamine and 2-bromoisobutyryl bromide is 1:(5 - 6.6):(12 - 15).

[0017] In some preferred embodiments, the mass ratio of the intermediate product, cuprous bromide, pentamethyldiethylenetriamine, and tert-butyl acrylate in step (2) is 1:(1.4 - 1.8):(1.7 - 2):(6 - 8).

[0018] In some preferred embodiments, the light absorbent is polydopamine nanoparticles with a particle size of 10 - 100 nm.

[0019] The second aspect of the present invention is to provide a gravure printing method for the gravure printing ink composition, which sequentially includes the following steps:

[0020] S1. Weigh each raw material in proportion and set aside for use;

[0021] S2. Stir and mix the polyacrylic acid emulsion and / or polyacrylate emulsion, the hydroxyacrylate monomer, the crosslinking agent, the lower alcohol solvent, the initiator, and the auxiliary agent, then add the pigment filler, continue to stir until evenly dispersed, and grind in a grinding machine to a desired fineness to obtain the aqueous gravure printing ink;

[0022] S3. Print the prepared aqueous gravure printing ink onto the printing substrate through a gravure printing machine, with a printing speed not greater than 220 m / min, a plate depth of 20 - 55 μm, a pressure of the doctor blade of 1 - 2.5 KN, and a pressure of the pressure roller of 0.2 - 0.3 Mpa; the printed printing substrate is dried in an oven, and finally wound by a take-up roller and slit by a slitting unit.

[0023] The beneficial effects of the present invention are as follows:

[0024] Aiming at the problems that the internal curing speed of the prior art using acrylate emulsion as a film-forming agent for gravure printing UV ink is far slower than that of the surface, the drying is slow, the adhesion is poor, etc., the present invention provides a gravure printing ink composition based on acrylate emulsion, and the curing speed of the resin connecting material is increased by introducing a cross-linking agent, and the adhesion and stability of the ink are improved at the same time. Specifically, the present invention uses pentaerythritol as a matrix, and obtains pentaerythritol ester containing isobutyl bromide through acylation reaction, and then polymerizes it with tert-butyl acrylate through atom transfer radical polymerization reaction to form a branched acrylate prepolymer, and adds the branched acrylate prepolymer as a cross-linking agent into the ink component, On the one hand, the unpolymerized double bonds at the end of the prepolymer can participate in photoinitiated polymerization, and the branched structure provides a highly cross-linked cured structure. At the same time, it can also produce ester exchange with the introduced hydroxy acrylate, further increasing the branching degree of the cross-linked network, greatly improving the drying speed and adhesion of the ink, and also promoting the maintenance of the stability of the ink to a certain extent; further, the present invention also introduces polydopamine nanoparticles as a light absorber, utilizing the unique broadband light absorption, efficient photothermal conversion and surface adhesion of polydopamine, to further improve the ink's absorption efficiency of curing ultraviolet light, further accelerate the curing speed, and at the same time improve the adhesion performance. DETAILED DESCRIPTION

[0025] The present invention is further described in conjunction with the following examples.

[0026] Example 1

[0027] A gravure printing ink composition, comprising the following components by weight: 20 parts of polyacrylic acid emulsion, 45 parts of polyacrylate emulsion, 7.8 parts of hydroxy acrylate monomer, 6.9 parts of crosslinking agent, 8.8 parts of low-grade alcohol solvent, 7 parts of pigment; 12 parts of filler, 2 parts of initiator, 1 part of dispersant, 0.6 parts of defoamer, 2.4 parts of pH regulator;

[0028] The preparation method of the cross-linking agent comprises the following steps:

[0029] (1) Weigh pentaerythritol and dissolve it in tetrahydrofuran solvent, add triethanolamine, stir and mix thoroughly, add 2-bromoisobutyryl bromide under protective atmosphere and ice water bath conditions, stir and mix again, and react at room temperature for 16 hours. After the reaction is completed, add dichloromethane to dilute the reaction system, and then use 10% HCl, 5% NaHCO 3 and deionized water, the organic phase is dried and then the solvent is evaporated, and then recrystallized and purified with methanol, and vacuum dried to obtain an intermediate product; the mass ratio of the pentaerythritol to the triethanolamine and the 2-bromoisobutyryl bromide is 2.72:16:36.8;

[0030] (2) Dissolve the intermediate product in a dimethylformamide solvent, add cuprous bromide, pentamethyldiethylenetriamine, and tert-butyl acrylate, heat to 75 °C under a protective atmosphere and stir for 0.5 h. After the reaction is completed, quickly cool with an ice-water bath, remove the catalyst by passing through an alkaline alumina column, add a cold methanol-water solution, fully stir and then separate the precipitate, and obtain it after vacuum drying; the mass ratio of the intermediate product to the cuprous bromide, the pentamethyldiethylenetriamine, and the tert-butyl acrylate is 1:1.6:1.9:7;

[0031] The solid content of the polyacrylic acid emulsion is 38 wt%, the polymerization molecular weight is 130,000 - 150,000, and the viscosity is 26 mPa·s;

[0032] The solid content of the polyacrylate emulsion is 41 wt%, the polymerization molecular weight is 130,000 - 150,000, and the viscosity is 37 mPa·s;

[0033] The hydroxyacrylate monomer is a mixture of 2-hydroxy-3-phenoxypropyl acrylate and β-hydroxyethyl methacrylate in an equimolar ratio;

[0034] The lower alcohol solvent is ethanol;

[0035] The pigment is carbon black; the filler is calcium carbonate;

[0036] The initiator is azobisisobutyronitrile; the dispersant is dispersant 5040; the defoamer is defoamer byk-028; the pH regulator is organic amine (AMP-95), which is used to control the pH value of the water-based ink to keep it stable at 8.0 - 9.5, avoid the ink viscosity from being too high or too low, and improve the printing suitability;

[0037] The gravure printing method of the gravure printing ink composition successively includes the following steps:

[0038] S1. Weigh each raw material according to the proportion for standby;

[0039] S2. Stir and mix the polyacrylic acid emulsion and / or polyacrylate emulsion, the hydroxyacrylate monomer, the crosslinking agent, the lower alcohol solvent, the initiator, and the additives, then add the pigment and filler, continue to stir until evenly dispersed, and grind in a grinder to the desired fineness to obtain the water-based gravure printing ink;

[0040] S3. Print the prepared water-based gravure printing ink onto the printing substrate through a gravure printing machine, with a printing speed not exceeding 220 m / min, a plate depth of 20 - 55 μm, a pressure of the doctor blade of 1 - 2.5 KN, and a pressure of the pressure roller of 0.2 - 0.3 Mpa; the printed printing substrate is dried through an oven, and finally wound by a take-up roller and slit by a slitting unit.

[0041] Example 2

[0042] A gravure printing ink composition, by weight, comprises the following components: 20 parts of polyacrylic acid emulsion, 45 parts of polyacrylate emulsion, 7.8 parts of hydroxyacrylate monomer, 6.9 parts of crosslinking agent, 8.8 parts of lower alcohol solvent, 7 parts of pigment, 12 parts of filler, 2 parts of initiator, 1 part of dispersant, 0.6 part of defoamer, 2.4 parts of pH regulator, and 1.3 parts of light absorber;

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

[0044] (1) Weigh pentaerythritol and dissolve it in tetrahydrofuran solvent, add triethanolamine, stir and mix well, add 2-bromoisobutyryl bromide under a protective atmosphere and ice-water bath conditions, stir and mix again, stir and react at room temperature for 16 h. After the reaction is completed, add dichloromethane to dilute the reaction system, and then wash successively with 10% HCl, 5% NaHCO 3 and deionized water. The organic phase is dried and the solvent is evaporated, and recrystallized and purified with methanol, and vacuum dried to obtain an intermediate product; the mass ratio of pentaerythritol to triethanolamine and 2-bromoisobutyryl bromide is 2.72:16:36.8;

[0045] (2) Dissolve the intermediate product in dimethylformamide solvent, add copper bromide, pentamethyldiethylenetriamine and tert-butyl acrylate, heat to 75 °C under a protective atmosphere and stir and react for 0.5 h. After the reaction is completed, quickly cool with an ice-water bath, remove the catalyst by passing through an alkaline alumina column, add a cold methanol aqueous solution, stir well and separate the precipitate, and vacuum dry to obtain; the mass ratio of the intermediate product to copper bromide, pentamethyldiethylenetriamine, and tert-butyl acrylate is 1:1.6:1.9:7;

[0046] The solid content of the polyacrylic acid emulsion is 38 wt%, the polymerization molecular weight is 130,000 - 150,000, and the viscosity is 26 mPa·s;

[0047] The solid content of the polyacrylate emulsion is 41 wt%, the polymerization molecular weight is 130,000 - 150,000, and the viscosity is 37 mPa·s;

[0048] The hydroxyacrylate monomer is a mixture of 2-hydroxy-3-phenoxypropyl acrylate and β-hydroxyethyl methacrylate in an equimolar ratio;

[0049] The lower alcohol solvent is ethanol;

[0050] The pigment is carbon black; the filler is calcium carbonate;

[0051] The initiator is azobisisobutyronitrile; the dispersant is dispersant 5040; the defoamer is defoamer BYK-028; the pH regulator is an organic amine (AMP-95), which is used to control the pH value of the water-based ink to stabilize it at 8.0-9.5, avoid excessive or low viscosity of the ink, and improve printability;

[0052] The light absorber is polydopamine nanoparticles with a particle size of 10-100 nm;

[0053] The gravure printing method of the gravure printing ink composition is the same as that of Example 1.

[0054] Example 3

[0055] A gravure printing ink composition, comprising the following components by weight: 20 parts of polyacrylic acid emulsion, 45 parts of polyacrylate emulsion, 7.8 parts of hydroxy acrylate monomer, 8.8 parts of low-grade alcohol solvent, 7 parts of pigment, 12 parts of filler, 2 parts of initiator, 1 part of dispersant, 0.6 parts of defoamer, 2.4 parts of pH regulator, and 1.3 parts of light absorber;

[0056] The polyacrylic acid emulsion has a solid content of 38 wt %, a polymerization molecular weight of 130,000-150,000, and a viscosity of 26 mPa·s;

[0057] The polyacrylate emulsion has a solid content of 41 wt%, a polymer molecular weight of 130,000-150,000, and a viscosity of 37 mPa·s;

[0058] The hydroxy acrylate monomer is a mixture of 2-hydroxy-3-phenoxypropyl acrylate and β-hydroxyethyl methacrylate in an equal molar ratio;

[0059] The lower alcohol solvent is ethanol;

[0060] The pigment is carbon black; the filler is calcium carbonate;

[0061] The initiator is azobisisobutyronitrile; the dispersant is dispersant 5040; the defoamer is defoamer BYK-028; the pH regulator is an organic amine (AMP-95), which is used to control the pH value of the water-based ink to stabilize it at 8.0-9.5, avoid excessive or low viscosity of the ink, and improve printability;

[0062] The light absorber is polydopamine nanoparticles with a particle size of 10-100 nm;

[0063] The gravure printing method of the gravure printing ink composition is the same as that of Example 1.

[0064] Example 4

[0065] An intaglio printing ink composition, by weight parts, comprises the following components: 20 parts of polyacrylic acid emulsion, 45 parts of polyacrylate emulsion, 7.8 parts of hydroxyacrylate monomer, 8.8 parts of lower alcohol solvent, 7 parts of pigment, 12 parts of filler, 2 parts of initiator, 1 part of dispersant, 0.6 part of defoamer, and 2.4 parts of pH regulator;

[0066] The polyacrylic acid emulsion has a solid content of 38 wt%, a polymerization molecular weight of 130,000 - 150,000, and a viscosity of 26 mPa·s;

[0067] The polyacrylate emulsion has a solid content of 41 wt%, a polymerization molecular weight of 130,000 - 150,000, and a viscosity of 37 mPa·s;

[0068] The hydroxyacrylate monomer is a mixture of 2-hydroxy-3-phenoxypropyl acrylate and β-hydroxyethyl methacrylate in an equimolar ratio;

[0069] The lower alcohol solvent is ethanol;

[0070] The pigment is carbon black; the filler is calcium carbonate;

[0071] The initiator is azobisisobutyronitrile; the dispersant is dispersant 5040; the defoamer is defoamer byk-028; the pH regulator is organic amine (AMP-95), which is used to control the pH value of the water-based ink to keep it stable at 8.0 - 9.5, avoid too high or too low ink viscosity, and improve printing suitability;

[0072] The intaglio printing method of the intaglio printing ink composition is the same as that in Example 1.

[0073] The performance of the intaglio printing ink compositions described in Examples 1 - 4 was tested. Among them, the adhesion was tested by the alcohol test method. Take the printed sheet and place it on a clean platform working surface (ink surface facing up); wrap the weight with a cotton cloth and soak the white cotton cloth with an appropriate amount of alcohol; wipe the surface of the printed product 10 - 15 times with the white cotton cloth soaked with alcohol (one round trip counts as one time); after wiping, check whether there is ink peeling on the surface of the printed product and whether there is ink staining on the surface of the white cotton cloth. The highest score is 10 points (no obvious ink peeling), and the lowest score is 0 points (ink peeling is greater than 80%); the viscosity was measured using a digital rotational viscometer at a rotation speed of 100 rpm (rotor 62#), a temperature of 25°C, and a relative humidity of 65%; for the drying property, 0.125 mL of ink was used to prepare a spread color sample on an aluminum cardboard, and UV light (lamp power 100 W / cm, irradiation energy of 20 mJ / (cm 2After the ((first)) irradiation, place the printed surface facing up on a flat plate, use the tail of a paper clip to scratch forcefully towards the edge, inspect the ink marks in the blank part, and judge the drying degree. The highest score is 10 points (completely cured), and the lowest score is 0 points (cannot be cured); the abrasion resistance refers to GB / T 3008-2008; the stability is to conduct 30 repeated freezing (at -20°C) and heating (at 75°C) tests on the ink, observe whether there is gelation or coarsening of the ink, and then score according to the ink condition. The highest score is 10 points (almost no change), and the lowest score is 0 points (extremely poor stability); the measurement results are as follows:

[0074]

[0075]

[0076] 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. A gravure printing ink composition, characterized in that The composition comprises the following components by weight: 40-80 parts of polyacrylic acid emulsion and / or polyacrylate emulsion, 5-15 parts of hydroxy acrylate monomer, 4-12 parts of crosslinking agent, 5-15 parts of low-grade alcohol solvent, 8-26 parts of pigment and filler, 1-8 parts of initiator, and 3-10 parts of auxiliary agent; The preparation method of the cross-linking agent comprises the following steps: (1) Weigh pentaerythritol and dissolve it in tetrahydrofuran solvent, add triethanolamine, stir and mix thoroughly, add 2-bromoisobutyryl bromide under protective atmosphere and ice water bath conditions, stir and mix again, and react at room temperature for 12-20 hours. After the reaction is completed, add dichloromethane to dilute the reaction system, and then wash with an acidic solution, an alkaline solution and deionized water in sequence. After drying the organic phase, evaporate the solvent, purify by recrystallization with methanol, and dry in vacuum to obtain an intermediate product; (2) The intermediate product is dissolved in dimethylformamide solvent, and cuprous bromide, pentamethyldiethylenetriamine and tert-butyl acrylate are added. The temperature is raised to 60-90° C. and stirred for reaction for 0.1-1 h under a protective atmosphere. After the reaction is completed, the reaction is rapidly cooled in an ice water bath, and the catalyst is removed by passing through an alkaline alumina column. A cold methanol aqueous solution is added, and the precipitate is separated after sufficient stirring, and vacuum drying is performed to obtain the product.

2. A gravure printing ink composition according to claim 1, characterized in that: The polymerization molecular weight of the polyacrylic acid emulsion and the polyacrylate emulsion is 100,000-150,000, the pH value is 6-8, and the solid content is 35-45%.

3. The gravure printing ink composition according to claim 1, characterized in that: The hydroxy acrylate monomer is one or more of 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, and β-hydroxypropyl methacrylate.

4. The gravure printing ink composition according to claim 1, characterized in that: The initiator is one or more of azobisisobutyronitrile, azobisisoheptylnitrile, dibenzoyl peroxide, potassium persulfate, tert-butyl hydroperoxide, ammonium persulfate, ferrous salt, cumene hydroperoxide, sodium bisulfite, and sodium thiosulfate.

5. The gravure printing ink composition according to claim 1, characterized in that: The color filler comprises a pigment and a filler, wherein the pigment is one or more of phthalocyanine pigment, carbon black and titanium dioxide; and the filler is one or more of matte powder, talcum powder, calcium carbonate and silicon dioxide.

6. The gravure printing ink composition according to claim 1, characterized in that: The auxiliary agent is one or more of a dispersant, an emulsifier, a stabilizer, a softener, a preservative, a defoamer, a pH adjuster, an adhesion promoter, an antistatic agent, a thickener, and a light absorber.

7. The gravure printing ink composition according to claim 1, characterized in that: The mass ratio of the pentaerythritol to the triethanolamine and the 2-bromoisobutyryl bromide in step (1) is 1:(5-6.6):(12-15).

8. The gravure printing ink composition according to claim 1, characterized in that: The mass ratio of the intermediate product to the cuprous bromide, the pentamethyldiethylenetriamine, and the tert-butyl acrylate in step (2) is 1:(1.4-1.8):(1.7-2):(6-8).

9. The gravure printing ink composition according to claim 6, characterized in that: The light absorber is polydopamine nanoparticles, and the particle size thereof is 10-100 nm.

10. A gravure printing method of a gravure printing ink composition according to any one of claims 1 to 9, characterized in that: The gravure printing method comprises the following steps in sequence: S1. Weigh each raw material in proportion and set aside; S2, mixing the polyacrylic acid emulsion and / or polyacrylate emulsion, the hydroxy acrylate monomer, the crosslinking agent, the low-grade alcohol solvent, the initiator and the auxiliary agent, adding the pigment and filler, continuing to stir until uniformly dispersed, and grinding in a grinder to a desired fineness to obtain the water-based gravure printing ink; S3. Print the prepared water-based gravure printing ink onto a printing substrate through a gravure printing machine, with a printing speed of no more than 220 m / min, a printing plate depth of 20-55 μm, a scraper pressure of 1-2.5 KN, and a pressure roller of 0.2-0.3 MPa; the printed substrate is dried in an oven, and finally rolled up by a receiving roller and slit by a slitting unit.

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