UV and IR dual-curing offset printing ink and preparation method thereof

Abstract

The invention discloses UV (ultraviolet) and IR (infrared) dual-cured offset printing ink and a preparation method thereof. The UV and IR dual-cured offset printing ink comprises 35-40% of UV-cured resin, 20-30% of UV-cured resin, 10-20% of UV-cured resin, 18-20% of IR curing resin; 5-10% of a reactive diluent; 4-6% of a photoinitiator; 15-20% of a pigment; 2-3% of an auxiliary agent; the UV curing resin is prepared from epoxy acrylic resin and polyurethane acrylate resin; the IR curing resin is alkyd resin containing a group capable of absorbing infrared rays; according to the offset printing ink disclosed by the invention, under the irradiation of UV light, the UV curing resin is rapidly subjected to a cross-linking reaction, so that rapid curing of the surface of the printing ink is realized; meanwhile, the IR curing resin in the ink is also crosslinked by virtue of IR irradiation, so that the ink on a thick ink layer or a material with poor UV light permeability can be completely cured, and the prepared ink has good wear resistance and chemical corrosion resistance.

Description

Technical Field

[0001] The present application relates to the technical field of coatings, and specifically relates to a UV and IR dual-curing offset printing ink and a preparation method thereof. Background Art

[0002] IR (infrared) curing technology uses the thermal effect of infrared rays to crosslink and cure components such as resins in the ink. It has the characteristics of uniform heat transfer and the ability to penetrate deep into the ink to initiate curing. However, the IR curing technology has a slow drying speed, low printing efficiency, and a relatively slow curing speed, which is not suitable for some printing scenarios that require rapid drying to enter the subsequent processing process; and a large amount of volatile organic compounds (VOCs) will be released during the drying process, causing harm to the environment and human health.

[0003] With the development of technology, UV (ultraviolet) curing technology has been widely used in offset printing inks due to its advantages such as fast curing speed, energy saving, and environmental protection. However, when printing with a thick ink layer of UV-curing ink or on some materials with poor UV light transmittance, incomplete curing is likely to occur, and the cost of UV curing equipment is relatively high, and there are certain requirements for the printing environment.

[0004] In the field of offset printing inks, the traditional single drying and curing of offset printing inks can no longer meet the actual production requirements. If the IR (infrared) curing technology and the UV (ultraviolet) curing technology can be combined to form a dual-curing system, the rapid reaction of the UV (ultraviolet) curing technology and the characteristics of uniform heat transfer of the IR (infrared) curing technology and the ability to penetrate deep into the ink to initiate curing can be combined to solve the problem that the single drying and curing technology of offset printing inks can no longer meet the production requirements.

[0005] At present, there are technical difficulties in the preparation of offset printing inks with UV and IR dual-curing. For example, UV curing relies on the rapid reaction (in seconds) of photoinitiators, while IR curing slowly initiates crosslinking through thermal effects (in minutes). If the two are not coordinated properly, it may lead to the obstruction of internal heat conduction after rapid surface curing, or material delamination due to incomplete internal curing, resulting in unstable curing effects; it is difficult for each component in the offset printing ink formula to meet the requirements of both UV curing (high light transmittance) and IR curing (thermal stability) at the same time, affecting the printing suitability and comprehensive performance of the ink, etc. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a UV and IR dual-curing offset printing ink and a preparation method thereof, and the technical solutions adopted include:

[0007] 40-45% of UV curing resin;

[0008] 15-20% of IR curing resin;

[0009] Reactive diluent: 5 - 10%;

[0010] Dispersant: 1 - 2%;

[0011] Photoinitiator: 4 - 6%;

[0012] Pigment: 15 - 20%;

[0013] Auxiliary agent: 2 - 3%;

[0014] The UV - curable resin includes epoxy acrylate resin and polyurethane acrylate resin;

[0015] The IR - curable resin is an alkyd resin containing groups that absorb infrared rays. A technical solution adopted by an embodiment of the present invention to solve its technical problems is: the IR - curable resin is an alkyd resin containing carbonyl groups, and the content of carbonyl groups is 5% - 10%.

[0016] A technical solution adopted by an embodiment of the present invention to solve its technical problems is: the pigment includes titanium dioxide surface - treated with a silane coupling agent.

[0017] This application also records a preparation method of the above - mentioned UV and IR dual - curable offset printing ink, including:

[0018] Step 1: Add the UV - curable resin, IR - curable resin, reactive diluent, photoinitiator and dispersant into a reaction kettle, stir at 40 - 60 °C for 30 - 60 min to preliminarily mix each component evenly to form a uniform mixture;

[0019] Step 2: Pigment dispersion: Add the pigment to the above - mentioned mixture, use a high - speed disperser for dispersion, control the rotation speed at 1000 - 1500 r / min, and the dispersion time is 60 - 90 min to fully disperse the pigment in the mixture to form a uniform color paste.

[0020] Step 3: Grinding: Transfer the color paste to a sand mill for grinding, select appropriate grinding media, and control the ratio of grinding media to color paste as 1:1 - 3:1;

[0021] Step 4: Post - mixing: Return the ground material to the reaction kettle, add the remaining defoamer and leveling agent, and continue to stir and mix for 30 - 60 min to evenly disperse the photoinitiator in the ink system.

[0022] Step 5: Filtration: Use a filtration device to filter the mixed ink to remove undispersed particles and impurities to obtain the UV and IR dual - curable offset printing ink.

[0023] One embodiment of the present invention solves the technical problem by adopting the following technical solution: During the grinding process, the rotation speed of the sand mill is adjusted to 1500 - 2500 r / min, and the grinding time is 90 - 120 min.

[0024] Advantages of the present invention:

[0025] The offset printing ink described in this application combines the advantages of UV and IR curing. Under UV light irradiation, the UV-curable resin rapidly undergoes a crosslinking reaction to achieve rapid curing of the ink surface. At the same time, IR irradiation causes the IR-curable resin inside the ink to also crosslink, ensuring that the ink on thick ink layers or materials with poor UV light transmittance can also be completely cured. After 500 abrasion tests with a 4-pound force, the surface of the ink is slightly worn. It has good tolerance to common chemical reagents such as alcohol and acetone. The prepared ink has good abrasion resistance and chemical corrosion resistance, greatly improving the curing efficiency and quality.

[0026] By reasonably selecting the reactive diluent and additives, the rheological properties of the ink are effectively regulated, making it have good fluidity and transferability, meeting the requirements of offset printing. The printed pattern is clear and the dots are complete.

[0027] Compared with relying solely on expensive UV curing equipment, after combining IR curing, the power and usage time of the UV curing equipment can be appropriately reduced, reducing equipment costs and energy consumption. Specific embodiments

[0028] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0029] The present invention will be further described in detail below with reference to specific embodiments and data. It should be understood that this embodiment is only for illustrating the present invention and does not limit the scope of the present invention in any way.

[0030] In the following embodiments, various processes and methods not described in detail are conventional methods well known in the art. The materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0031] The offset printing ink with dual UV and IR curing in this application is characterized by including:

[0032] 40 - 45% of UV-curable resin;

[0033] 15 - 20% of IR-curable resin;

[0034] 5 - 10% of reactive diluent;

[0035] 1 - 2% of dispersant;

[0036] Photoinitiator: 4 - 6%;

[0037] Pigment: 15 - 20%;

[0038] Auxiliary agent: 2 - 3%;

[0039] The UV - curable resin includes epoxy acrylate resin and polyurethane acrylate resin; Epoxy acrylate has high reactivity and curing speed, and can quickly undergo cross - linking reaction under UV light irradiation; Polyurethane acrylate endows the ink with good flexibility and abrasion resistance.

[0040] The IR - curable resin is an alkyd resin containing groups that absorb infrared rays. In this application, an alkyd resin containing carbonyl groups is used. For example, an alkyd resin formed by polycondensation of dihydric alcohol and dibasic acid is selected, and the carbonyl content in its molecular chain is 5% - 10%. Under IR irradiation, the carbonyl group absorbs infrared energy, triggering the thermal motion and cross - linking reaction of the molecular chain.

[0041] The photoinitiator includes a UV photoinitiator, which has high absorption efficiency for UV light and can quickly generate free radicals to initiate the UV curing reaction.

[0042] Pigment: Selected according to printing requirements, such as Millenium Titanium Dioxide (white pigment), Jiangxi Black Cat Carbon Black (black pigment), Shanghai Yalian Phthalocyanine Blue (blue pigment), Clariant Magenta (red pigment), etc. The pigment needs to be surface - treated to improve its dispersibility and stability in the ink system. For example, a silane coupling agent is used to surface - treat titanium dioxide to enhance its affinity with the resin and prevent pigment agglomeration.

[0043] Leveling agent and defoaming agent: The leveling agent can reduce the surface tension of the ink, improve the leveling property of the ink, and make the printed film layer uniform and flat; The defoaming agent can eliminate the bubbles generated during the preparation and printing of the ink, ensuring the printing quality.

[0044] The dispersant is preferably Lubrizol polymer - type dispersant, which can adsorb on the surface of the pigment through the anchoring group, form a stable dispersion system, and improve the dispersion effect and lasting effect of the pigment.

[0045] The components and sources of the above raw materials are shown in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] The preparation method of the offset printing ink with dual UV and IR curing described in Table 1 includes:

[0050] Step 1: Add UV curable resin, IR curable resin, reactive diluent, photoinitiator and dispersant into a reaction kettle, stir at 40 - 60 °C for 30 - 60 min to preliminarily mix each component evenly and form a uniform mixed solution;

[0051] Step 2: Pigment dispersion: Add pigment into the above mixed solution, disperse it using a high - speed disperser, control the rotation speed at 1000 - 1500 r / min, and the dispersion time at 60 - 90 min to fully disperse the pigment in the mixed solution and form a uniform color paste;

[0052] Step 3: Grinding: Transfer the color paste to a sand mill for grinding, select appropriate grinding media such as zirconia beads, control the ratio of grinding media to color paste at 1:1 - 3:1; during the grinding process, adjust the rotation speed of the sand mill to 1500 - 2500 r / min, and the grinding time to 90 - 120 min to refine the pigment particles to less than 5 microns and improve the fineness and dispersion stability of the ink.

[0053] Step 4: Post - mixing: Return the ground material to the reaction kettle, add the remaining defoamer and leveling agent, and continue to stir and mix for 30 - 60 min to evenly disperse the photoinitiator in the ink system;

[0054] Step 5: Filtration: Use a filtration device such as a 100 - 200 - mesh filter screen to filter the mixed ink, remove undispersed particles and impurities, and obtain the finished offset printing ink with dual UV and IR curing.

[0055] Based on the above content, Embodiment 1 and Embodiment 2 of the present application are proposed, and the content of each component of the raw materials in Embodiment 1 and 2 is shown in Table 2.

[0056] Table 2

[0057]

[0058] The preparation method of the offset printing ink with dual UV and IR curing in Embodiment 1 specifically includes:

[0059] During premixing, epoxy acrylate, polyurethane acrylate resin, alkyd resin containing carbonyl, trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 184 (1-hydroxycyclohexyl phenyl ketone), TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), 1173 (2-hydroxy-2-methyl-1-phenylpropanone), MBF (methyl benzoylformate), co-initiator active amine, and polymeric dispersant were successively added to the reaction kettle and stirred at 50 °C for 45 min; pigment magenta was added and dispersed at a speed of 1200 r / min with a high-speed disperser for 75 min; during grinding, the material was transferred to a sand mill, zirconia beads were added, the speed of the sand mill was controlled at 2000 r / min, and grinding was carried out for 100 min; during post-mixing, defoamer and leveling agent were added and stirred for 45 min; finally, filtration was carried out through a 150-mesh filter screen to obtain a white UV and IR dual-curing offset printing red ink.

[0060] The preparation method of the UV and IR dual-curing offset printing ink in Example 2 specifically includes:

[0061] During premixing, epoxy acrylate, polyurethane acrylate resin, alkyd resin containing carbonyl, hydroxymethylpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 184 (1-hydroxycyclohexyl phenyl ketone), TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), 1173 (2-hydroxy-2-methyl-1-phenylpropanone), co-initiator active amine, and polymeric dispersant were successively added to the reaction kettle and stirred at 45 °C for 50 min; pigment carbon black was added and dispersed at a speed of 1300 r / min with a high-speed disperser for 80 min; during grinding, the material was transferred to a sand mill, zirconia beads were added, the speed of the sand mill was controlled at 2200 r / min, and grinding was carried out for 110 min; during post-mixing, defoamer and leveling agent were added and mixed and stirred for 50 min; finally, filtration was carried out through a 150-mesh filter screen to obtain a black UV and IR dual-curing offset printing black ink.

[0062] The offset printing inks prepared in Example 1 and Example 2 were subjected to printing suitability tests. The printing suitability tests showed that the inks transferred smoothly during offset printing and the printed patterns were clear.

[0063] The printed pattern was irradiated with UV light (Shenzhen Kezhiyi, wavelength 200 - 400 nm, power 60 W / cm 2 ) for 1 s, and then irradiated with IR (Yancheng Kepeng Electric Heating Technology drying tunnel, wavelength 900 - 1300 nm, power 6 KW) for 10 s, and the ink was completely cured;

[0064] The cured ink pattern was subjected to a wear resistance test. After 500 times of 4-pound force, there was only slight wear on the ink surface; wiping the surface with ethyl alcohol 50 times showed no fading, which met the expectations.

[0065] Of course, the present invention is not limited to the above embodiments. Those skilled in the art can make equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations and substitutions are all included in the scope defined by the claims of this application.

Claims

1. A UV and IR dual-curing offset printing ink, characterized in that: include: UV curing resin 40-45%; IR curing resin 15-20%; Active diluent 5-10%; Dispersant 1-2%; Photoinitiator 4-6%; Pigment 15-20%; Additives 2-3%; The UV curable resin includes epoxy acrylic resin and polyurethane acrylate resin; the IR curable resin is an alkyd resin containing a group that absorbs infrared rays.

2. The UV and IR dual-curing offset printing ink according to claim 1, characterized in that: The IR curing resin is an alkyd resin containing a carbonyl group, and the content of the carbonyl group is 5% to 10%.

3. The UV and IR dual-curing offset printing ink according to claim 1, characterized in that: The pigment comprises titanium dioxide surface-treated with a silane coupling agent.

4. A method for preparing the UV and IR dual-curing offset printing ink as claimed in claim 1, characterized in that: include: Step 1, adding UV curing resin, IR curing resin, active diluent, photoinitiator and dispersant into a reaction kettle, stirring at 40-60° C. for 30-60 minutes to preliminarily mix the components to form a uniform mixed solution; Step 2, pigment dispersion: add pigment to the above mixed solution, use a high-speed disperser to disperse, control the speed at 1000-1500r / min, and the dispersion time is 60-90min, so that the pigment is fully dispersed in the mixed solution to form a uniform color paste; Step 3, grinding: transfer the color paste to a sand mill for grinding, select appropriate grinding media, and control the ratio of grinding media to color paste to be 1:1 to 3:1; Step 4, post-mixing: return the ground material to the reactor, add the remaining defoamer and leveling agent, and continue stirring and mixing for 30 to 60 minutes to evenly disperse the photoinitiator in the ink system. Step 5, filtration: Use filtering equipment to filter the mixed ink to remove undispersed particles and impurities to obtain UV and IR dual-curing offset ink.

5. The method for preparing the UV and IR dual-curing offset printing ink according to claim 4, characterized in that: During the grinding process, the speed of the sand mill is adjusted to 1500-2500 r / min and the grinding time is 90-120 min.

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