UV Pad Printing Inks and Reference Formulas
Pad printing ink can be divided into three categories according to the drying method, namely, volatile drying type (one-component), two-component heating curing and room temperature curing type, UV curing type.
Volatile drying pad printing ink is currently commonly used varieties, containing a large number of fast-drying organic solvents, printing relies on the solvent evaporation, ink viscosity increases to achieve the transfer of ink from the pad printing stencil through the pad printing head to the substrate. Its drawbacks are low hardness and abrasion resistance, poor solvent resistance, and inability to be used for demanding products. In addition, a large number of organic solvents evaporate into the air during printing, which not only pollutes the environment, but also seriously harms the health of workers.
Two-component curing ink containing curing agent, but also contains a large number of volatile solvents, after printing the pattern to be baked at high temperatures or placed at room temperature for 1 to 2 days, so that the ink through the air oxidation and drying, improve the hardness and abrasion resistance of the ink, but the low production efficiency, there are still problems of environmental pollution, and can not be used for heat-sensitive substrates such as plastic products.
UV pad printing ink combines the advantages of pad printing and UV instantaneous curing in one, not only can the irregular or uneven surface of the object for printing, give full play to the advantages of pad printing technology, but also can make the printed pattern by UV curing with excellent hardness, abrasion resistance, brightness and solvent resistance.
UV ink for pad printing is a major breakthrough in pad printing technology, the advantages are as follows:
UV pad printing ink does not contain or contain very little volatile organic solvents, completely changed the printing environment, to ensure the health of workers, greatly reducing the pollution of the environment.
② fast curing. UV pad printing ink using special light curing equipment, printing can be made through ultraviolet radiation to make the ink in a very short period of time curing, can be wet wet multi-color printing, and produce excellent printing results, greatly improving production efficiency.
UV curing process has nothing to do with the ambient temperature, even if the temperature is low or high, as usual, can be printed, a variety of materials such as metal, glass, leather, heat-sensitive plastic products can be pad printing.
Excellent physical and chemical properties: UV curing ink layer has excellent hardness, abrasion resistance and solvent resistance, which is incomparable with general solvent-based pad printing ink, so UV curing ink is generally used for high-quality products.
⑤ Ease of use. In general, UV pad printing ink can be opened to print, without adding a lot of diluent, which is determined by the composition of UV ink, ink composition changes in the printing process is small.
⑥ Strong sense of three-dimensionality. When the etching depth of the pad printing plate is unchanged, the text pattern printed by UV pad printing ink, the height of the ink layer basically does not change after light-setting, and the sense of concavity and convexity is especially obvious.
UV pad printing ink according to its printing substrate can be simply divided into UV pad printing ink for metal, UV pad printing ink for plastics two types of UV pad printing ink, for the thick ink layer, physical and chemical performance requirements of high electronic products and double curing UV pad printing ink.
UV pad printing ink printing should be for different properties of the substrate to take different methods of treatment, such as PP, PE, PET and other difficult to adhere to the product, you can take the flame method, corona method and other pre-treatment to increase the polarity of the substrate to improve the fastness of adhesion of UV pad printing ink. PP or PE special treatment water can also be used to directly rub the surface of PP, PE products, natural drying, you can print, adhesion fastness is excellent. For ABS, PVC, PMMA, PC, nylon, copper, aluminum, stainless steel, glass and other materials can be directly pad printing, have good adhesion properties.
In general, UV pad printing ink curing order is as follows: red, yellow, green, blue, black, white, gold, silver. The lighter the ink color, the thinner the ink layer, the faster the curing; the deeper the color, the thicker the ink layer, the slower the curing. The darker the color, the thicker the ink layer, the slower the curing. When pad printing, the darker color should be printed first, followed by the lighter color.
Double curing pad printing ink by UV irradiation, the ink has been initially cured, the surface has a certain hardness, printed products can be stacked or overlapped together, in order to make the curing film performance to achieve the best, usually also have to carry out heat curing, curing conditions for 130 ℃, 10 ~ 20min.
UV pad printing ink requires pad printing adhesive tip of the ink oligomer and active diluent transferability to be good, but because the pad printing adhesive tip is mainly made of silicone rubber, silicone rubber and acrylate oligomer and active diluent affinity is very poor, thus affecting the transfer efficiency of the ink. In addition, solvent-based ink can be added to the necessary fillers to improve the print trim neatness, but UV pad printing ink can not add too much filler, filler in addition to affecting the curing efficiency, but also affects the transparency of the ink; in the development of UV pad printing ink, to ensure that the pigment color concentration is high and transparency, transferability is good, which is also a greater difficulty.
The formula design of UV Pad Printing Ink can refer to “3.2 UV Screen Printing Ink”.
(1) UV Pad Printing Ink Reference Formulation
PUA 35
PEA 25
651 3
ITX 2
907 3
Pigment 25
Butyl acetate 1
Polysiloxane defoamer 1
Vinyl ether 5
(2) UV Pad Printing White Glass Ink Reference Formulation
Trifunctionality PEA 20
ACMO 8
LA 5
907 3
DETX 0.3
TPO 2
Co-initiator EHA 2
Titanium dioxide R-706 20
Titanium dioxide R-900 25
Defoamer S43 0.5
Defoamer Arix920 2
Leveling agent RAD2200 0.3
(3) UV pad printing black glass ink reference formula
Trifunctionality PEA 25
Bifunctionality PEA 15
ACMO 8
LA 10
907 3
DETX 1
TPO 2
Co-initiator EDAB 1
Co-initiator DMBI 1
Carbon Black 8
Defoamer Arix920 3
Leveling agent RAD2300 0.3
(4) UV Pad Printing Red Glass Ink Reference Formulation
Trifunctionality PEA 25
Bifunctionality PEA 15
ACMO 7
LA 10
907 3
DETX 1
184 3
Co-initiator EDAB 1
Co-initiator EHA 1
Magenta (57:1) 12
Defoamer EFKA-4050 1
Antifoam agent KS66 0.5
Leveling agent BYK306 0.3
(5) UV pad printing blue glass ink reference formula
Trifunctionality PEA 20
Bifunctionality PEA 10
ACMO 10
LA 10
907 4
DETX 0.3
TPO 2
Co-initiator EHA 1
Phthalocyanine Blue 15
Defoamer Arix920 0.5
Leveling agent BYK163 0.3
Ink performance:
Light curing speed (80W/cm2) 3～6s
Adhesion (scratch method) 100/100
Ethanol resistance (95% ethanol) 100 times
Acetone resistance 50 times
Acid resistance (5% sulfuric acid) 16h
Alkali resistance (5% NaOH) 12h
Boiling resistance (100℃ boiling water) 1h No peeling off
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