Flexo Printing 1000 Questions (231-247)

231 How to detect fineness of flexo alcohol-soluble ink?
Fineness reflects the degree of dispersion of pigments and fillers in the binder, which is an important indicator of the ink. It is related to the printing performance of the ink. The determination method refers to the lithographic ink fineness test method GB559-83.

232 How to detect the viscosity of flexo alcohol-soluble ink?
There are two ways to measure viscosity: one is to measure the relative viscosity, and the other is to measure the absolute viscosity and measure it with a rotary viscometer. Refer to GB/T13217.4-91 for the determination method.

233 How to detect the dryness of flexo alcohol-soluble inks?
The dryness of the flexo-alcoholic inks is tested in the same way as for the drying of inks. See Printing Technology, 2003, 36, 48. “218 How to detect the drying speed of ink?”
have to be aware of is:
(1) The timing and operation must be synchronized.
(2) Dry ink should be carefully observed when wet and dry.
(3) The two tests must be done 3 times, and the average value should be taken; the error of primary dryness should not exceed 0.5mm, and the error of thoroughness should not exceed 0.5s.

234 flexible version of UV ink What are the characteristics?
Ultraviolet (UV) curing technology has been hailed as “21st Century Green Industry New Technology” because it fully complies with the 3E principles of future development, namely Energy-Saving (Energy Conservation), Ecology (Eco-Environmental Protection), and Efficient (Efficient) . With the continuous enhancement of environmental awareness and the rapid development of high and new technology, UV curing technology has also gained more and more applications in the field of printing inks. UV printing inks were invented in the 1960s, but flexographic UV inks began to be used in flexographic printing after the 1990s, and were mainly used for the printing of fine products. Compared with traditional inks, UV inks have the characteristics of energy saving, low pollution, cost-effectiveness, and good printability.

How does 235 flexible UV ink save energy?
UV inks only require the radiant energy used to excite the photoinitiators. Instant UV chemical inks can transform the liquid UV ink into a solid ink film. Traditional thermal curing requires heating the substrate, material, and surrounding space to evaporate. Removing the heat of the diluting organic solvent consumes a large amount of energy, and the general thermal curing energy consumption is 5 times that of the ultraviolet curing energy.

236 flexible version of UV ink how to reflect the characteristics of the small?
The UV ink basically does not contain organic solvents, and the solid content is basically 100%. The active monomers used for dilution are all involved in the photocuring reaction, and the energy used for the light curing is electric energy, no fuel, no fuel gas, and no CO2 generation. Reduced environmental pollution and possible fire or explosion accidents.

237 flexible version of UV ink how to reflect the economic and efficient characteristics?
UV ink curing speed, can be completed in one second, improve the production efficiency; no need to spray powder, product stacking will not occur blocking, saving the semi-product stacking site, to meet the requirements of large-scale automated production.

238 flexible version of UV ink protection products how to reflect the characteristics?
UV inks can be cured at low temperatures to avoid damage to various heat-sensitive substrates at high temperatures during heat curing. Therefore, UV inks are most suitable for the printing of various heat-sensitive material substrates.

239 flexible version of UV printing ink printability characteristics how to reflect?
The UV ink has good printability, the printing process does not change the physical properties, the dot gain is small, and the printing quality is excellent. In terms of glossiness, sharpness, color saturation and other aspects, they are obviously superior to traditional inks; UV inks are superior to traditional inks in terms of water resistance, alcohol resistance, abrasion resistance, and chemical resistance.

240 flexo UV ink itself what are the advantages?
In addition to the above features, UV ink has its own advantages, such as smaller viscosity than other inks. The viscosity of general flexographic UV inks ranges from 250 to 2000CP/25°C; the viscosity is small, and the general viscosity range is from 2 to 4/. 25 °C; UV ink ink layer thickness is generally 2 ~ 5μm; curing speed is generally 60 ~ 150m/min, the fastest can exceed 500m/min.

241 What is the composition of the flexographic UV ink?
Flexographic UV inks are mainly composed of oligomers, reactive diluents, photoinitiators and sensitizers, pigments, auxiliaries and the like. According to the requirements of different substrates, these components can be combined to achieve the best performance of flexographic UV inks.

242 oligomers performance?
Oligomers, also known as prepolymers, are low molecular weight polymers containing saturated functional groups, most of which are acrylate oligomers. They are the main components of flexographic UV inks and their properties determine the main properties of the cured ink film. . In general, the oligomer has a large molecular weight, a high curing speed, a small volume shrinkage at the time of curing, and a good adhesion of the cured ink film to the substrate. However, its large molecular weight, viscosity viscosity flexo UV ink increases, the fluidity becomes worse, need to add more reactive diluent, which also reduces the role of oligomers in the formula. Therefore, the choice of alignment polymer is an important part of the flexographic UV ink formulation design.

What are the 243 oligomers?
There are many types of oligomers with different properties. The main ones used are: epoxy acrylates, polyester acrylates, urethane acrylates, and polyether acrylates. Different oligomers have different characteristics. When preparing flexographic UV inks, different oligomers should be carefully used in conjunction with different substrates and pigments in order to obtain ideal results.

244 What kinds of epoxy acrylates are included and what are their characteristics?
Epoxy acrylates are the most commonly used oligomers in the UV curing field. They mainly include bisphenol A epoxy acrylates, phenolic epoxy acrylates, epoxidized oil acrylates, acids and anhydrides. Epoxy acrylate and several other.
The flexographic UV inks made of bisphenol A epoxy acrylates have high gloss, high hardness, high tensile strength, good chemical resistance, and fast curing speed, but the ink film is brittle and flexible. Poor performance, the viscosity of oligomers.
Epoxidized oil acrylates are also used in flexographic UV inks. Epoxidized soy oil acrylate is generally used. It has good wetting of pigments, good adhesion to many substrates, and good flexibility. It is less irritating to the skin and cheaper, but it has a slower speed.
Acid and anhydride modified epoxy acrylates are also commonly used in flexographic UV inks. The purpose of modification is many: some introduce flexible long chains in order to overcome the brittleness of the epoxy; some are not introduced. Saturated double chain, in order to improve the curing speed, improve the performance of the ink film; some increase the molecular weight of the oligomer, in order to reduce the shrinkage of the curing and so on. In this way, there are a variety of epoxy acrylate oligomers with different properties that can be selected for use in flexographic UV inks, while also increasing the range of substrates.

What are the characteristics of 245 polyester acrylate?
Compared with epoxy acrylates, polyester acrylates have lower viscosity, good wettability to pigments, and good adhesion to plastics, so they are often used in conjunction with other oligomers to increase adhesion to substrates. However, its anti-yellowing properties are not good.

What are the characteristics of 246 urethane acrylate?
Urethane acrylate, also known as urethane acrylate, has great room for adjustment due to its composition and chemical properties. Therefore, it is possible to synthesize a variety of urethane acrylates with different functionalities, different properties, different viscosities, and different molecular weights. Polymer. The ink film printed with its flexographic UV ink has excellent mechanical resistance, flexibility, impact resistance and chemical resistance, high and low temperature resistance, good yellowing resistance, and good adhesion to plastics. Efforts, but more expensive, are currently considered only when the performance of other oligomers does not meet the requirements.

What are the characteristics of 247 polyether acrylate?
The most important feature of polyether acrylate is yellowing resistance, good flexibility, adjustable range of photospeed, small viscosity, good wetting property of pigment, but its tensile strength and hardness are relatively low, and it is resistant to chemicals. Bad performance. Therefore, polyether acrylates are sometimes used in small quantities in general flexographic UV inks and are mainly used for wetting pigments and as reactive diluents for better leveling performance of flexographic UV inks.