Nano Ink Properties and Applications

1. Talking about the fineness and purity of ink

It is well-known that the fineness and purity of the ink are critical to the quality of the print. To print high-quality products, high-fineness, high-purity inks must be guaranteed. Therefore, improving the fineness and purity of the ink is an important part of the study of new inks. Ink fineness refers to the size and pigment of the pigment (including filler) particles in the ink. Filler distribution in the material evenness. Therefore, how the fineness of the ink affects the quality of the printed product at the same time affects the printing rate of the printing plate. In the process of practice, color printing products are printed with a net print, and the on-site layout contains small yin and yin, and the printing process is susceptible to quality problems such as scumming. If not carefully checked and analyzed, it is likely to fall into the wrong operation, thinking that Inadequate ink consistency, too high viscosity, too much ink or too much pressure and blind adjustments. As everyone knows, the real reason is the poor ink fineness. The fineness of the ink is directly related to the nature of the pigments, filling families and the size of the particles. In general, inks made with inorganic pigments (excluding carbon black) are not high in fineness and have relatively coarse particles, which has a great bearing on the rolling process of the ink. The more times the ink is ground in the rolling process, the finer the ink particles, the larger the contact area between the pigment particles and the binder, and the better the printing performance. Obviously, the fineness of the ink is closely related to the quality of the printed matter. In the case of printed anilox printing, if the ratio of ink particles to the dot area is close to that, it is easy to make the dots empty or spread, or even the printing defects of the dots are not smooth. Therefore, the finer the ink, the finer the dots on the printed material The clearer and fuller it is. In addition, the finer the ink, the greater its concentration, the stronger the coloring power, and the higher the print quality of the product. On the contrary, the fineness of the ink is low, the pigment particles are coarse, the friction coefficient during the printing process is large, and the printing durability of the printing plate is low. And coarse-grained ink, it is easy to produce stencil printing, ink deposition, and ink transfer, ink inequality. The fineness of the ink can generally be observed and judged by the naked eye. That is, if the surface scraped by the ink knife shows a smooth and uniform visual effect, the fineness of the ink is good. If the scraped surface shows a lumpy or granular rough layer, the fineness of the ink is poor. In addition, a small amount of ink can be coated with coated paper, and then the other layer of paper can be used to grind the ink layer. If the ink layer is still very smooth when it is dragged to a very thin thickness, the fineness of the ink is good. If traces of the ink layer appear, it is clear that the traces are caused by coarse particles of pigments or fillers in the ink, indicating that the fineness of the ink is not good enough. Of course, the above is only judged by experience, and the accuracy of the judgment has certain limitations. To achieve standardized, data-based judgment, only rely on fineness meter to determine the size of pigment particles in order to more accurately detect the fineness of the ink. The specific method for determining the fineness of the ink with a fineness meter is to dilute the sample ink to a certain degree, place it in the deepest part of the fineness meter, and then use a spatula to move the groove (to maintain a constant speed) to the shallowest position. Both sides of the groove can be seen at the scale of the size of the ink particles. In addition, the size of the ink pigment particles can also be observed with a microscope.

2. Nano Ink Properties

(1) Experiments show that the absorption of light waves by nano-metal particles is different from ordinary materials. Nano-metal particles can absorb light waves and make themselves appear black. At the same time, nano-metal particles also have a scattering effect on light. Using the characteristics of nano-metal particles, nano-metal particles can be added to the black ink to produce nano-black ink, thereby greatly improving the purity and density of the black ink.

(2) Studies have shown that after chemical modification of the surface of the nano-semiconductor particles, the medium surrounding the particles can strongly influence the optical properties, which is reflected in the red-shift or blue-shift of the absorption spectrum. Experiments have shown that there is a clear blue shift in the light absorption edge of CdS nanoparticles and a large red shift in TiO2 nanoparticles. Accordingly, if they are separately added to the yellow ink and the cyan ink to make the nano ink, the purity of the yellow ink and the cyan ink can be greatly increased. Printing of color prints using nano-inks with specific nano-particles can make prints more plentiful, and the tone is more distinct, which greatly enhances the expressiveness of the details of the images, thereby obtaining high-quality prints. Today, with the help of high technology, various components (inks, pigments, fillers, etc.) in ink can be made into nano-scale raw materials. This makes it possible to achieve better flowability and lubricity due to their high degree of fineness and good fluidity. The dispersed suspension and stability, less pigment, high hiding power, good gloss, delicate resin particle size, continuous film formation, smooth and uniform, film layer book, make the printed image clear. If used in UV inks, the curing speed can be accelerated, and shrinkage and wrinkling of the ink film can be eliminated due to uniform dispersion of the filler.

(3) In the glass-ceramic ink, if the composition of the inorganic material is nano-scale fineness, a large amount of raw materials can be saved and a more exquisite high-quality image can be printed. Nanotechnology brings a huge change to the ink manufacturing industry in terms of pigments. Instead of relying on chemical pigments, inks can be selected to have different colors by selecting the appropriate volume of nanoparticles. For example, nanoparticles of TiO2 and SIO2 are white and Cr2O3 is Green, Fe2O3 is brown. Inorganic nanomaterials such as Al2O3 have good fluidity, and if added to the ink, the abrasion resistance of the ink film can be greatly improved. Nano-scale carbon ink is conductive, has a good shielding effect on static electricity, to prevent electric signals from being disturbed by external static electricity. If it is added to ink, it can be made into conductive ink, such as large-capacity integrated circuits, modern contact panel switches, etc. . In addition, if Ag is made into nano-scale instead of micro-sized Ag in conductive ink, 50% of Ag powder can be saved. This conductive ink can be directly printed on ceramic and metal, and the ink film is thin and even and smooth. If the Cu, Ni material is made of 0.1 ~ 1μm ultrafine particles, it can replace palladium and silver and other precious metals conductive. Therefore, the combination of nanotechnology and anti-counterfeiting technology will open up another vast area of ​​security ink.

(4) In addition, some nanoparticles have luminescent groups, such as "-N-N" nanoparticles can emit light by themselves. The printed matter printed with the ink added with this type of nano-particles can be recognized by the human eye without the irradiation of an external light source by itself, and can be used for anti-counterfeit printing to achieve a good first-line anti-counterfeit effect; for outdoor large-scale advertising printing Photographic prints that are read or read at night also do not require the use of external light sources, which saves energy and greatly facilitates users.

(5) As the nanoparticles have good surface wettability, they are adsorbed on the surface of the ink pigment particles, can greatly improve the ink's lipophilicity and wettability, and can ensure the stability of the entire ink dispersion system, so the addition of nanometer The printability of nanoparticulate inks is greatly improved. It is believed that with the further development of nanomaterial technology, more nanomaterials with different characteristics will be recognized and used by people. Applying these nanomaterials to ink manufacturing, special inks with different uses can be obtained for confidential use. Document printing, various security printing, and printing of various handicrafts can achieve extraordinary results. 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 to non-magnetic toners, thereby making a single-component copying developer, which can be saved. Raw materials and improve copy quality. As for the source of nanomaterials, in fact, there are many methods for obtaining nanomaterials, such as high-temperature sintering (such as carbon nanotube sintering technology), precipitation method, high-temperature water dissolution method, chemical vapor condensation method, and modern plasma energy polymerization method.

3. Nano anti-counterfeiting ink application

Nanotechnology has been applied to the development and production of inks. Gratifying results have been achieved. Especially for anti-counterfeit ink applications, nanotechnology and anti-counterfeiting technologies have been combined. Nano-anti-counterfeiting printing inks developed and developed have not only good printing results, but also The anti-counterfeiting effect and anti-counterfeiting performance can be further improved. For example, for the current situation that fluorescent anti-counterfeit inks have poor light resistance and the anti-counterfeiting mechanism has been deciphered and the anti-counterfeiting function is lost, the nano anti-counterfeit inks that have been successfully researched by Guangzhou University for near-infrared absorption have reliable performance, safety, stability, and aging resistance. All aspects have reached a satisfactory level. At present, this product has been applied to high-tech fields such as packaging, ticket security and infrared sensors.