Understand the water-based ink system

The main function of "water" is to make the ink more fluid, so that the ink can be brought from the engraved ink tank of the pattern roller to the printed body.

There is hardly any kind of printing like today's Flexo printing

The same is so rapid progress. In a very short period of time, it was printed from people's impressions only as "bags" and was transformed into high-quality photocopying. With such an overall development in such a short period of time, it is difficult to use the general assessment as the merit of the industry or the supplier. Of course, these advances are more than just ink suppliers.

Flexo printing is not a single job. Nowadays we have pre-pring and post-print for old, slow machines and new high-speed machines for corrugated cartons.
Flexible packaging with wide spoke and narrow spoke plastic film Flexo
Printing; paper printing including face and napkins; there are many different printed bodies, narrow-spoke Flexo printing such as labels, tickets, coupons and the latest development of Flexo UV carton printing.

In addition, we have many different water-based inks and solvent-based inks. We can choose from a variety of inks and ink systems. Regardless of raw materials or formulas, printing inks are not a secret or a surprise, nor do they trust a practice or must use a certain practice to achieve high quality.

Today I hope to browse some formulas about water-based printing inks. What exactly is ink? What are the ingredients? What will be the effect? Of course, such a short space is hard to cover all the details, so I only give you a little idea.

What is printing ink?

It is a chemical mixture. The water-based printing ink referred to by Flexo printing is low viscosity, and its viscosity is measured by a standard measuring cup.

What is water-based ink?

Water-based printing ink is a combination of four different chemical raw materials. They are:

Pigment - it conveys the visual sense so that we can see the color.
Resin - it will transfer color to the surface of the printed body.
Additives - It is a combination of some raw materials to correct the performance of ink.
Solvent - It reduces the viscosity so that the ink can be transferred to the printed body more easily and then dried.

Of course, the solvent of water-based printing ink must be water, but some suppliers still mix some flammable solvents, also known as water-based printing inks.

For now, the main function of ink is to present a message or display a selling point. It is also often a perfect picture, so the most important part of printing ink is toner.

The colorant is one of a dye or a pigment. The dye is a general color agent and can be found in foods with colorants and ballpoint pen inks.
Although the printing effect is not good and is easy to fade, some paper and board printing are still used due to low prices.

Today's high-quality inks are chemically synthesized using pigments, with the exception of the famous carbon blacks and a large number of dioxides. The fact is that the appearance of the pigment and its properties come from the resin that carries it. More than one hundred pigments are formulated into inks to cover the spectrum of all colors.
However, in normal use, typical ink formulations are limited to about 50 types.

Some of the world's pigment manufacturers include BASF in Germany, as well as some very small factories. Pigments are manufactured in batches, but the color of each factory is slightly different. The common four-color inks: blue, magenta, yellow, and black, each have a little bit of difference, and there is no real standard. In particular, the colors that the Oriental and Western markets place their emphasis on are different. Take the magenta ink as an example. The east prefers blue ones and the west prefers yellow ones.

Pigments are expensive components in inks and increase costs due to the requirement for higher resistance and higher color strength.

The choice of printed material will also affect the choice of pigments. For example, there is a special case where we are asked to make a blue ink.
It will be printed on white cardboard, but the yellow kraft board is used for proofing.

Another part of the ink formulation is a resin or carrier transfer system. The main function of the resin here is to transfer the pigment from the printing process to the printed body. In the first step of these processes, the resin is dissolved in a solvent and passes through the printing plate to the object to be printed. After the solvent is absorbed or evaporated and dried, the resin is left to bear and maintain the color. We have a lot of resins to choose from, but it's not possible to use just one resin. Maybe we will consider different resins for the printing requirements, such as: high temperature resistance, acid resistance, high gloss...

Typical resins for aqueous inks are:

The first element of ink composition is “water”. Its main function is to make the ink more fluid, so that the ink can be brought from the engraved ink groove of the pattern roller to the printed object, and the resin and the pigment are brought to the printed material. In the body, more water must be removed, which is more difficult on the non-absorbent printed material, so the removal rate and drying speed are very important in the printing process.

The water in the ink is limited to organic solvents because it affects the drying speed of the water and reduces the dissolving power. The water in the ink is not sluggishly added. The pH, hardness, and softness of the water all affect the dryness. Soon we talked about the pH of the water
value.

Additives are the least in the formulation of aqueous inks, and its addition is the best manifestation or correction of the ink. There are many kinds of additives, we must choose its function, and it can be completely combined with ink components. Additives include surface smoothing agents, defoamers,
Levelers, synthetic resins, and more.

Here we talk about the use of certain raw materials, such as heavy metals, chemical solvents, synthetic resins, etc. These will cause environmental problems. I recall that some suppliers mentioned earlier did not restrict the use of such materials according to standards. There are still many problems in this area in Asia. Although the government's laws and regulations are not strictly regulated, you must consider exporting.

A typical printing ink composition would be:

Solvent 70%

10% of color material

Additive 5%

Resin 15%

Of course, this is only a rough figure, and the final decision must be made based on the requirements of printing ink and printing quality. For today's high-quality Flexo printing, the pigment content can be added to 17%, which is to say that we can consider the need to adjust the proportion of ingredients. The most important thing for a printer is to achieve satisfactory quality at an acceptable cost; and also to take into account environmental protection and health issues.

The basic concept of printing ink has already existed, but I would like to state that this is the simplest version. Let's go back to the viscosity problem (
Viscosity ), each of the factors we talked about above will affect the viscosity.

Often ink companies ask you what viscosity you need, or recommend what viscosity you use. However, ink viscosity is very important, whether it is a job change to another job, or the press is changed to another press, or other situations may have different viscosities. It depends on several aspects, different printing models, with ink roller, scraper or different pattern wheel and mesh thickness. Often ink companies ask you what viscosity you need, or recommend what viscosity you use. However, the ink viscosity is very important, whether it is a job for another job, or the press for another press, or other situations may have different viscosities. It depends on several aspects, different printing models, with ink roller, scraper or different pattern wheel and mesh thickness.

Viscosity is easily measured in the cup, but attention must be paid to changes in temperature and the cleaning and protection of the measuring cup.

In dryness, evaporation of water is a very important factor, especially in non-absorbing materials, which can use an energy to evaporate the solvent. Water's humidity is the coefficient of surface tension of the water and a coefficient between the printed objects. The water will naturally form a minimum surface area, adjacent to the boundary of the printed body so that it cannot be wetted. The drying of the water-based printing ink absorbs both the imprinted body and the imprinted body. It is clear that the imprinted body, such as a plastic film, does not absorb water unless it is absorbed. Even if it absorbs the imprinted body, it can only hold a considerable amount of water, but
The fruit water and the resin are not completely absorbed and separated during drying, that is, the water volume of the printed matter is saturated, and the watermark ink that no longer absorbs the ink will not be dried. At this time, there will be a color shift if worn.

pH is a very important factor in aqueous inks, and lack of control or incorrect pH can cause many problems.
The PH value is a measure of the solvent's acidity. The pH range is from 0 to 14, but it is not necessary to stare at the numbers 6 and 7 too much.
Or 8 or 9, because there are also people who use 100, 800, or 900. What is really paying attention? That is, PH value affects the viscosity of aqueous ink. In typical aqueous inks, it can be seen from the graph that the general pH range should be between 8 and 9.

Several simple steps to control the ink:

Of course, there are other simple QCs that you can use to control the ink. Even if there are problems, it can be easily solved.