·Introduction: ink composition, material and ink selection

Printing is defined as the industrial reproduction of graphics by transferring ink to the surface of the substrate through various pressures. The traditional printing uses the printing plate as the intermediate carrier of the graphic, so that the graphic area and the blank area are isolated by various means, and then The ink was transferred to the surface of the product. Digital printing took the plate aside and transferred the graphic in the computer directly to the surface of the product. The evolution of the technology developed in the direction of the quickest, but it seemed that the printing did not abandon the signs of ink.

Composition of ink

Content is the most fundamental purpose of printing, but to convey content, color plays a very important role. Nature can express many things in color. Ink experts first think of pigments and dyes that have long preservation periods and bright colors.

Pigments are also good dyes, can not be directly printed on the surface of the product, pigments and dyes can be firmly attached to the surface of the product should be attributed to the resin. Most of the resins are solid, and most of the resin in the ink is not a pure resin, but a mixture that dissolves into a solvent.

Ink is composed of pigments, resins, and solvents. All printing inks lack the above three components.

Pad printing inks and screen printing inks

Different printing processes do not have the same requirements for inks, and they must also add appropriate supplementary components to the inks to make them easier to use in specific applications. For example, offset inks have higher viscosity, good water resistance, and gravure printing inks are relatively thin. , good fluidity; screen printing inks must have good permeability.

The main difference between inks used in different printing processes is that the additives contained in the inks are different. This article will mainly focus on screen printing inks and pad printing inks.

In terms of substrate suitability, screen printing has great advantages, especially in the amorphous plastic hardware and direct consumer goods industries. Screen printing has been widely praised. However, there is no universal printing method in the world, and screen printing is no exception. In the area of ​​industrial printing on the surface of small areas and irregular substrates, silk screen printing encountered real troubles, and this trouble caused the birth of pad printing technology. It can be said that although there are great differences between pad printing technology and screen printing, the industries involved are very similar.

The earliest printing inks were replaced by screen printing inks. Practice has proved that there is absolutely no accommodation. However, inks used in different printing environments must have different applicability. For example, pad printing inks do not require users to have the permeability of screen printing inks, but they are required to have better thixotropy and surface dryness. To ensure that the transfer process from the steel plate to the plastic head and substrate is more accurate. The use of special pad printing inks will undoubtedly make it easier to improve the print quality.

MARABU pioneered the development of special pad printing inks. The effect of the additive keeps the surface tension of the ink within a constant range so that the ink transfer during the printing process remains absolutely consistent.

The ink transfer process is closely linked with the nature of the print head. The surface tension of the print head is controlled within a similar range to that of the print ink. This appears to be a systematic project. The essential purpose is to improve the ink transfer efficiency. The Japanese have solved this problem from another angle. They installed a plastic head cleaning device on the pad printer. However, the installed plastic head cleaning device mainly controls the amount of ink transferred, and the transfer efficiency has not improved.

MARABU has 6 (actually 8) pad printing inks to choose from: GL, mainly used on metal, ceramic, glass surface, basically a two-component ink, need to add GLH hardener, TPR, is in SR The improved printing inks based on the series of screen printing inks, all the materials that SR can make in the printing process can make TPR; the same reason, TPY is an improved printing ink based on PY series screen printing inks. TPU inks can be used on surfaces that are very difficult to print; TPT is a pad printing ink that is primarily used on pad printing machines: TPL has better stability and can maintain good uniformity over long rubbing conditions. There are two kinds of TPP and TPS.

It is worth noting that screen printing inks and pad printing inks are completely universal, but only need to add additives to change the printability. Therefore, when there is no special pad printing ink, screen printing ink can be used instead.

Ink color: primary color, spot color, standard color

Natural colors are rich and colorful, and it is impossible for them to be represented by all inks. There are two methods of copying colors in printing. One is to directly mix spot colors for printing, and the other is to print by four-color overlay.

The four colors are based on the principle of superimposition of four color materials in the CMYK color model. In general, the four-color reproduction technology can basically return the colors we require. Four-color copying techniques are generally used for manuscripts having a level.

The advantage of copying four-color inks lies in the level of originals. For most advertising designs and creative and industrial printing, the use of spot colors is a very common phenomenon. Spot color is more able to reflect the designer's ideas, but also more easily prevent infringement. In theory, spot colors can also be used in the original tones, but not only does the hue match perfectly, the possibility of wasting ink increases. Therefore, the copying of printing technology includes two-sided copying techniques. One is the tendency to use four-color inks to reproduce colors, which is mainly used when the originals are hierarchical and there is a case where the colors and the colors are superposed. Primary color printing is the most difficult technology to master because it involves complex chromatics and dot synthesis. How to control the change of dot from original to film, printing plate and substrate is the core link of primary color printing technology.

Spot colors are used in places where colors do not overlap with each other. Due to the unusually rich pigments in the natural world, there are many kinds of spot color inks. - In a general sense, spot colors are all colors other than the primary colors, and there are infinitely many spot colors. PANTONE Corporation of the United States formulated the color standard for ink spot color, and the color cards that are commonly used today are printed according to the spot color ink produced.

PANTONE color card is actually a very small part of the spot color, we call it the standard color. Now that Europe has also developed a European standard color, we can see these two standard colors as a subset of all spot colors. Of course, a variety of spot colors can also be allocated to a variety of spot colors in various color card printing standard colors. Color cards are the common language of printing companies in the world.

What kind of red is the red color, nobody can tell, but if you tell the PANTONE color number, you can easily find this kind of ink. Whether the ink manufacturer can provide ink in accordance with the standard color card production relates to the vital interests of the user. Selecting the ink color is an important content. Although the four-color printing technology is difficult to grasp, it seems very simple to select the primary color ink because the ink manufacturer produces There is only one set of four-color inks. In contrast, the choice of spot color ink is a lot more troublesome. If the designer happens to use a standard color to express his design ideas, and you just bought the ink, then you can only use this kind of ink. , but fewer and fewer designers will do this, perhaps the boss will not allow him to do so, because the easier it is to get, counterfeiting is also simple. The deployment of inks is also based on the subtractive method in color science, but it is necessary to quickly deploy an accurate color, as important as theory and experience.

Material and ink selection

Offset and other printing methods may not be so troublesome, because the printability of paper is very good, basically do not consider adhesion problems, but screen printing and pad printing is not so simple, silk screen and pad printing materials are many, it is impossible to use Instead of an ink, an ink manufacturer must produce a wide variety of inks in order to fully adapt to the market.

We can simply divide the printing materials into the following categories:

1. PP and PE, in the plastics family, PP, PE are two kinds of materials with very large amounts. The first is that they have very good physical properties, chemical resistance is very good, most of the solvents can not do them, so in the coating , cosmetics, plastic films and electrical products have a wide range of uses. But this is also the reason why they are difficult to print, because their constituent molecules are non-polar molecules. At present, prepress printing methods are commonly used for printing these two kinds of materials. The more common methods are flame treatment and high frequency processing. The Pl treated water produced by MARABU is actually a strong oxidizer, and the good adhesion of the ink is achieved by forming a rough surface on the surface of the oxidized material. The development of PP-free inks is also a goal of many manufacturers, and the technology is basically mature, but the non-handling inks are not well attached to PE surfaces. MARBU's PP series inks are free-handling inks.

In combination with prepress processing, the types of inks that can be used on the surface of PP and PE are many. We are talking about solvent inks here. For UV inks, prepress processing is also a must. At present, there are no UV inks that are free from treatment. It should be said that in the current printing technology field, it is difficult to achieve stable quality control by printing on PP and PE materials.

2. Some polar materials such as ABS, PC, PVC, PS, and AS are easy to print. Most of these materials can be printed without prepress processing. This ink is the strength of all manufacturers.

3. The substrates such as glass, metal and ceramics do not have any absorption properties on the surface, and the inks manufactured according to the conventional methods are difficult to work. In most cases, two-component inks are used.

Nowadays, more and more enterprises are engaged in moving and printing screen printing. The ability to find inks suitable for customers' products means the ability to obtain orders. However, suppliers' information shows that they can fit this material. To determine whether they can really meet the requirements, the key is to perform tests as required. If the test results are not good, you may want to replace the ink. Sometimes you may get the wrong information and technology, so we must understand the test method, many inks can not achieve the printing method of the product, the wrong test method is an important reason for this result. If some problems cannot be solved, please contact the ink manufacturers in time.

The important information provided in the previous description is to first understand what the customer's product is, and secondly to be familiar with the ink selection information, and then meticulously experiment until the customer is satisfied. In theory, there are no products that cannot be printed. In fact, many product printings are annoying to you. The key is whether there are enough test methods to solve them.

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