The hottest transparent ink brings infinite busine

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Transparent ink brings infinite business opportunities to the flexible packaging industry

as people have higher requirements for packaging, packaging and makeup. For the external type, the external design package has been installed more and more to the facade, "color" is the easiest to attract people's attention when they start developing products. Nowadays, the outer packaging of commodities in shopping malls tends to be highly transparent, giving people a feeling of glittering, and its ultimate purpose is to arouse consumers' desire to buy. In the field of flexible packaging, there is an ink that can meet the above requirements, which is a transparent ink with high transparency. Transparent ink in the use process, often with aluminum film or aluminum foil backing, its effect is extremely obvious, the visual effect is also the best. Now transparent ink has been widely used in the flexible packaging industry, specifically in the food industry and other high-end flexible packaging. In the actual use process, some quality phenomena often occur, such as pitting and uneven ink spreading after transparent ink printing, which greatly reduces its expected effect. This paper will explain the nature of transparent ink and printing matters in combination with practice

types and characteristics of transparent inks

transparent inks are made by fine grinding with high-grade transparent pigments and high-grade transparent resins as the main raw materials, plus other additives. It can be divided into surface printing transparent ink and internal printing (composite) transparent ink. Compared with other types of inks, transparent inks have the characteristics of high viscosity, high transparency, high brightness, bright colors, firm adhesion and strong coloring power. The fineness of transparent ink is generally below 10urn, so its coverage and transferability are better than other inks, but the surface printing transparent ink is not as heat-resistant as the internal printing transparent ink 180 d=5a. When designing packaging bags, there are generally less transparent inks at the heat sealing knife pressure. Surface printing transparent inks generally have a high temperature resistance of about 120 ℃. Of course, some ink manufacturers have produced more high temperature resistant transparent inks. It is better not to mix surface printing transparent inks or internal printing (composite) transparent inks produced by different manufacturers. Packaging enterprises often think that since they all belong to the same resin type inks, they can be mixed, resulting in many quality problems

application of transparent ink

when printing with transparent ink, white is generally not used as the bottom of the color scheme, because white plays an extinction role, which will greatly reduce its use effect and value. Relatively speaking, the color table printed with transparent ink is 0.01 mm thinner than that with white ink. Ep~, J of transparent ink can't get high brightness and bright colors without aluminized film or aluminum foil paper, aluminum foil and other materials, because the transparency of transparent ink is very high, and it will change when compounded with aluminized film or directly printed on the above materials, so as to reveal the luster and color of metal, making yellow yellow, green green, red and red with excellent effect. In terms of transparency, there are several kinds of transparent golden yellow, transparent yellow, transparent light yellow (blue) and so on developed by surface printing transparent ink. And if the transparent golden yellow is compounded on the aluminized film, it is even more glittering. The transparent golden yellow is extremely transparent. It is also often used in self matching gold, and can also be padded with gold powder. According to the requirements of customers, you can choose to deploy and connect with the fatigue loading experiment control module, such as self prepared gold ink with gold powder, gold oil, transparent golden yellow. The golden yellow ink prepared in the ratio of 1:3:2 not only brightens the golden light, but also greatly enhances its adhesion. Its application is as follows:

■ making dazzling flowers and gift wrapping paper of color strips, ribbons, etc. It is made of transparent inks (red, yellow, green, blue, etc.) and then coated with aluminum film. It is a single adhesive film

■ after printing transparent ink, the inner layer of the flexible packaging bag made of aluminum film composite or the small inner bag made of aluminum film after printing, such as the conjunctiva, belong to more than two layers of film, which has been widely used in the food industry

● generally, it is made into high-end packaging such as cartons, cartons and New Year pictures by aluminizing after printing and then adding them to the paper. Its prints have the advantages of waterproof and moisture-proof

■ after printing with anti-counterfeiting materials, it is printed with transparent ink, and then covered with laser film, which is conducive to the anti-counterfeiting of prints, and at the same time, it will make the appearance colorful and radiant. In order to achieve an optimal effect, it should be considered that not all transparent ink color schemes should be used when designing plate making, but transparent ink printing can be used locally. Better effect

reasonable choice of transparent ink

about how to choose transparent ink. We can consider the following three aspects:

■ when printing, we should choose the ink suitable for the substrate material. For example, when printing the surface printed aluminum handle conjunctiva, we must choose the surface printed transparent ink. If you want to print BOPP and composite aluminum plating, you should choose the internal composite ink (transparent). Therefore, it can be said that the type of printing materials determines the type of ink used. Even the same kind of film materials are often different due to different varieties and grades, so we should not make a mistake

■ it should be selected correctly according to the samples provided by customers. The selection of transparent ink includes hue and color. It is necessary to consult the production supplier when mixing spot color transparent ink. The difficulty of mixing spot color of transparent ink is significantly higher than that of opaque ink

■ the choice should also be made according to the actual situation, and the parameters of high temperature resistance, sunlight resistance, permeability resistance and so on must be included in the selection

printing and fault phenomenon of transparent ink

■ it is necessary to fully stir the transparent ink before printing. If it is cold in winter, the surface printing transparent ink should not add too much diluent and viscosity due to its low viscosity. Generally, it is better to control it at 3 × cup in 18-22 seconds, and then adjust the angle of the scraper, the pressure of the embossing cylinder and the distance between the scraper and the embossing point according to the depth of the printing plate. If the solvent ratio is misadjusted, the viscosity control is improper, or the process operation is wrong, many faults are likely to occur, so every link should not be sloppy

■ it is easy to produce "pitting" when printing transparent ink. After the printed product is coated with aluminum film, its flashing effect comes out, but careful observation will find that its surface has pinhole shape, as if it was not printed. There are several such factors:

① the surface of the printing glue roller is not fine enough, or there are dust and foreign matters, and the printing is pushed in the middle

② plasticizers, lubricants, etc. contained in the film float on the surface, hindering the normal transfer and lubrication of the ink

③ the viscosity of the ink is too high, drying too fast, or the lack of separation of the adhesive causes the transfer, and the wettability adaptation is poor

④ increase the pressure of the printing glue pressing roller, which is generally about 4kg. If the pitting is regular, carefully check whether the printing plate and the rubber roller are defective, and remake the plate or replace the rubber roller

■ adhesion occurs after printing transparent ink. In the plum rain season with high temperature and humidity, after the plastic film is gravure printed, adhesion occurs between the winding and placement, and the transparent ink falls into blocks, and even the transparent ink cannot be separated from the lower plastic film, resulting in waste products

most of the adhesion factors are due to the sticky ink, too high humidity and too much pressure. The specific factors are as follows:

1. Internal factors: the heat resistance of the ink itself is poor. For example, when the paint is dry, we can't see it with the naked eye. After the printed matter is rolled up, the residual solvent is difficult to evaporate, and the resin in the ink cannot be dried and solidified, resulting in serious adhesion of the finished product. The increase of residual solvent will not only affect its firmness, but also be extremely detrimental to food and produce peculiar smell. In addition, the additives in the printed materials will also cause the ink to become sticky

2. External factors: adhesion caused by improper control. At room temperature, the ink will also soften when the finished product without quality problems in the operation and use of printed matter encounters high temperature. Adhesion occurs. Therefore, it is required that the operating temperature and use temperature of the printed matter should not exceed 40 ℃ - 50 ℃. In addition, too tight winding and too large winding tension will also cause adhesion. The solution is to control the printing drying temperature and relax the tension, and the winding should not be too tight

3. Other reasons: the ink is not firmly adhered to the substrate, such as there is no good adhesion between the ink and the substrate. It is easy to transfer and produce adhesion after winding. The solution is to correctly select the ink and control the quality of the ink to make it adapt to the substrate. In addition, the surface treatment of the substrate to improve its affinity for ink is also a way to reduce ink adhesion. Generally, the BOPP surface provides excellent supporting services for the aluminum industry, and the tension is ≥ 38 dyne

the gloss is not high after aluminum plating with transparent ink. The reasons for this phenomenon are as follows:

the transparency of the ink itself is poor

the solvent dries too fast and the viscosity is too low during printing; The uniformity of aluminized aluminum layer is poor, resulting in poor reflective gloss:

the angle of the doctor blade is too large, and the hole of the printing plate is shallow. The solution is: A. replace the ink with good transparency; b. Use slow drying solvent to improve viscosity; c. Replace the composite aluminum plating, and the aluminum plating layer shall be uniform without pinhole shape; D adjust the doctor blade. Generally, the included angle should be controlled at 35 degrees

in order to get the best effect when printing transparent inks, we must start from all aspects, and we should choose and print according to the actual situation

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