Several high-tech ink characteristics (2)

Studies have shown that after chemical modification of the surface of the nano-semiconductor particles, the surrounding medium of the particles can strongly affect the optical properties, showing a red-shift or blue-shift of the absorption spectrum. Experiments have shown that there is a clear blue shift in the light-absorbing edge of the Cds nanoparticles and a large red shift in the absorption edge of the TiO2 nanoparticles. Accordingly, if they are added to yellow and cyan inks to make nano inks, their purity can be improved. The use of nano-inks with specific nano-particles to reproduce printed color prints will result in a richer hierarchy, a clearer tone, and a greater ability to express the details of the image.

Nowadays, with the help of high technology, various components in inks ( such as resins, pigments, fillers, etc. ) can be made into nano-scale raw materials. In this way, due to its high degree of fineness and fine flow and lubricity, it can achieve better dispersion and suspension, stability, low pigment content, high hiding power, good gloss, fine resin particle size, continuous and uniform film formation, Thin film, print images more clearly. If used in UV inks, the curing speed can be accelerated, and shrinkage and wrinkling of the ink film can be eliminated due to the fine and uniform dispersion of the filler. In the glass-ceramic ink, if the inorganic material is made into nano-scale fineness, it will save a lot of raw materials and print more refined and more beautiful high-quality images. This brings a huge change to the ink manufacturing industry, so that instead of relying on chemical pigments, it chooses the appropriate volume of nanoparticles to present different colors. Because there are substances in the nanoscale, the different sizes of the particles are also different, or different substances of different colors, such as TiO2 , SiO2 in the nanoparticles is white, Cr2O3 is green, Fe2O3 is brown, and inorganic nanomaterials such as nano- Al2O3 have very Good fluidity, if added to the ink can greatly improve the wear resistance of the ink film. Nano-scale carbon ink is conductive, has a good shielding effect on static electricity, to prevent the signal from external static electricity interference, if it is added to the ink can be made into conductive ink, such as large-capacity integrated circuits, modern contact panel switches, etc. . In addition, in the conductive ink, such as the Ag made of nano-level instead of micron Ag , can save 50% of Ag powder, the conductive ink can be printed directly on the ceramic and metal, the ink film is thin and uniform smooth, very good performance it is good. If Cu, 0.1 ~ 1 μ m made of Ni material ultrafine particles, which can be used instead of palladium and silver and other precious metal conductive. Therefore, the combination of nanotechnology and anti-counterfeiting technology will open up another broad field of security ink.

In addition, some nano-particles themselves have luminescent groups that may emit light themselves, such as " -N ≡ N -" nanoparticles. Prints printed with inks containing this kind of particles can be recognized by human eyes without external light source irradiation, and can also be used for anti-counterfeit printing; they can be used for outdoor large-scale advertising printing or nighttime printing. Photographic prints that are read will no longer require external light sources, which will not only save energy, but also greatly facilitate users.

Because nanoparticles have good surface wetting properties, they are adsorbed on the surface of the pigment particles in the ink, which can greatly improve the ink's lipophilicity and wettability, and can ensure the stability of the entire ink dispersion system. Therefore, nanoparticles are added with nanoparticles. Nano ink printing performance is greatly improved. With the further development of nanomaterial technology, it is believed that more nanomaterials with different characteristics will be recognized and used by people.

In electrostatic copying, magnetic nanopowders are used instead of non-magnetic toners, which are widely used today, to eliminate the need to add ferromagnetic particles as a carrier in non-magnetic toners and to make a single-component copying developer. Raw materials and improve copy quality.

As for the source of nanomaterials. In fact, there are many ways to obtain nanomaterials, such as high-temperature sintering ( such as sintering of carbon nanotubes ) , precipitation, high-temperature dissolution, chemical vapor-phase condensation, or modern plasma energy polymerization.

II. Cationic inks

In recent years, the use of photo-curing (UV) technology in flexographic printing has played an important role in the printing of paper and film materials. The UV technology has moved from a narrow web of letterpress printing to the flexographic printing market. In offset printing, we also saw the advantages of UV ink quick drying system, which can shorten the printing cycle and reduce the workload. The most important feature of UV curing system is that it can improve the printing stability ( drying ) , and shorten the time waiting for oxidation drying in the printing process. In the past 10 years, UV printing has had a great impact on the traditional, mainly on the plastic substrate flexographic printing.

Nowadays, there are new ink-cationic inks. It increases the environmental protection and quality of flexographic printing and increases its guarantee. Compared with the free radical system, the cationic ink has the advantages of low volatility and small odor, and can be said to be a very good environmental protection ink. The odor of free radical inks is a big headache and it is harmful to the health of operators and the environment. Cationic inks ( low-volatile inks ) have great advantages in this regard, and are now even used in some food packaging industries. Cationic inks also have the benefit of being attached to a plastic substrate. Cationic inks and coating glosses exhibit particularly good adhesion to electro-smoothed films, which is the most critical of all advantages.  

Compared with radical inks, cationic inks have a moderate cure speed ( which is slightly inferior to free radical inks ) , can be cured for a second time ( approximately 24 hours ) , have no resistance to oxidation, are slightly affected by humidity, and have no shrinkage. Excellent sexual characteristics.

Although in terms of curing speed, radical inks can be dried at high speeds, the curing speed of cationic inks is slightly behind. However, recent research and development shows that the improved cationic ink can also adapt to 150-200m/ min printing.  

The benefit of re-curing is that when the printed product is output from the printer, the ink film looks as if it has cured, but there is still no reaction ( not dried ) . Cationic curing techniques can continue to react until most of these materials react. In contrast, radical inks can only be exposed to UV light for thorough drying. This process, in turn, leads to higher volatilization, especially if unreacted low molecular weight components are more volatile. The cured polymer is usually of high molecular weight and generally does not volatilize. Volatilization of volatiles is also reflected in the extractable components. The content of extractables is an increasingly important feature of testing food packaging systems. In particular, as an analytical technique, the content of the extractable component is one part per billion, and even an amount of one trillion parts is now being discussed as an indicator of the content of the packaged product. Cationic inks have a small amount of shrinkage and therefore have good adhesion characteristics.  

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