Application essentials of transparent ink in packa

2022-05-19
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Essentials of using transparent ink in packaging and printing (II)

selection and application of transparent ink

selection and application of transparent ink should be carried out according to different substrate characteristics and customer requirements. To sum up, it is mainly considered from the following three aspects to reasonably select transparent ink

1 select the appropriate ink according to the printing material: for example, when printing the surface printing aluminized film, the surface printing transparent ink must be selected; when printing BOPP film and composite aluminized film, the inner printing transparent (composite) ink should be selected. 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. In addition, it should be noted that when printing with transparent ink, the size of the friction surface is generally measured under the color scheme, and then the measurement benchmark is used. White is not used as the bottom, because white plays the role of extinction, which will greatly reduce its use effect and value. Relatively speaking, the color case printed with transparent ink is mm thinner than that with white ink

2. Choose suitable transparent ink according to the samples provided by customers: the selection of transparent ink includes hue and color If you want to deploy spot color transparent ink, you must consult the production supplier, because the deployment of spot color of transparent ink is different from general spot color ink, and its difficulty is significantly higher than that of opaque ink

3. Select the corresponding transparent ink according to the actual situation and purpose of the packaging: such as high temperature resistance, sun resistance, permeability resistance and other parameters of packaging printing materials, which must be included in the consideration of selection. In addition, in order to obtain high brightness and bright colors, transparent ink printing cannot be separated from materials such as aluminum film or aluminum foil paper and aluminum foil, because the transparency of transparent ink is very high. When it is combined with aluminum film or printed directly on the above materials, it will change to show the luster and color of metal Make yellow more yellow, green more green, red more red, the effect is better

now Transparent ink has developed a variety of transparent golden yellow, transparent yellow, transparent light blue and so on. If the transparent golden yellow is compounded on the aluminized film, it is even more glittering: because of its high transparency, the transparent golden yellow is often used in self prepared gold, and can also be padded with gold powder. At the same time, the golden yellow ink can be prepared according to the customer's requirements, such as golden yellow and golden yellow. At the same time, it can be adjusted according to the ratio of 1:2:3. At present, transparent ink is mainly used to print dazzling flowers and gift gold paper such as color strips and ribbons. These wrapping papers are made of transparent ink (red, yellow, green, blue, etc.) and then aluminized or surface printed with aluminized film It belongs to single adhesive layer film. After printing transparent ink, the inner layer is compounded with aluminized film to make soft packaging bag or small inner bag conjunctive film made after printing aluminized film. These films belong to more than two layers and have been widely used in the food industry. In addition, high-grade packaging prints such as cartons, cartons and New Year pictures are made by printing with transparent ink, aluminizing and then returning to the paper. The prints have the advantages of waterproof and moisture-proof. After printing with anti-counterfeiting materials, printing with transparent ink and then covered with laser holographic film can not only improve the anti-counterfeiting effect, but also make the appearance colorful and radiant. In order to achieve the best effect, it is not necessary to use transparent ink in the design, but only use transparent ink in local printing, which can get better effect. Transparent ink belongs to dry special ink. Due to its different formula, the use method is also different from that of general ink

the transparent ink must be fully stirred before printing. If the surface printing transparent ink is printed in cold winter, due to its low drillability, it is not suitable to add too much diluent. The drillability is generally controlled at 3 seconds Then adjust the angle of the doctor blade, the pressure of the embossing cylinder and the distance between the doctor blade and the embossing point according to the depth of the printing plate

if the solvent ratio is out of balance, the drill control is improper or the process operation is wrong, it is very likely to lead to many faults, so every link should not be careless

troubleshooting of common faults in transparent ink printing

transparent ink in the process of flexible packaging printing, aluminum film or aluminum foil is often used to improve the printing and visual effect. However, in the actual use process, some quality phenomena often occur, such as pitting and uneven ink laying after transparent ink printing, which greatly reduces its expected effect. Therefore, we should be familiar with the properties and printing characteristics of transparent ink and analyze and eliminate it

1. The main reason and solution of pitting phenomenon during transparent ink printing is that after the printed product is coated with aluminum film, the flashing effect comes out, but careful observation will find that there are pinholes on the surface, as if it had not been printed. The main reasons for this failure are:

① the surface of the embossing cot is not fine enough, or there are foreign matters such as dust, which causes the ink here to continue straight and not thick enough after-sales of our experimental machine. Check whether there is dirt on the embossing rubber roller and wipe its surface clean; Check the quality of cots Replace the qualified rubber roller

② plasticizers and lubricants contained in the film float on the surface, hindering the normal transfer and lubrication of ink. Before printing, the plastic film shall be preheated and other prepress treatment shall be carried out, and the film heating printing shall be carried out. If not, the appropriate plastic film shall be replaced

③ poor ink transfer and wetting adaptability due to too high ink penetration, too fast drying or lack of drilling agent. The ink penetration should be properly reduced and slow solvent should be used

④ the printing pressure is too low. The printing pressure can be properly increased and exhausted, and the printing pressure can be well controlled (generally about 4kg)

⑤ for the problem of printing plate or embossing rubber roller (the pitting is regular), carefully check whether the printing plate and embossing rubber roller are defective. If so, make plate again or replace the rubber roller

2. Adhesion after printing transparent ink

main reasons and solutions: in the plum rain season of high temperature and high humidity, the plastic film is easy to adhere during winding and placing dishes after gravure printing. The transparent ink is stuck in blocks, and it can not even be separated from the lower plastic film at the ink, resulting in a large number of waste products. The adhesion of printed products is mostly caused by ink drilling, too high environmental humidity and too high pressure, mainly caused by turbulence. ① The ink itself has poor heat resistance and produces greater drillability under high temperature conditions. When the ink is dry, it cannot be seen with the naked eye. Because the residual solvent is difficult to evaporate after the printed articles are rolled up, the resin in the ink cannot be dried and solidified, resulting in serious adhesion of the finished products. Too much residual solvent in the ink will cause serious adhesion of the finished products after winding. Too much residual solvent will not only affect its firmness, but also be extremely unfavorable to food, resulting in peculiar smell of packaging products. ② Because the ambient temperature is too high, it will cause the ink to soften, resulting in print adhesion. At room temperature, many prints using transparent ink are normal in operation and use, but when printing at high temperature, the ink will soften and produce adhesion. Therefore, it is required that the ambient temperature for the operation and use of printing materials should not exceed 50 ℃, and it is best to control it below 45 ℃. 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 There is no good adhesion between ink and substrate The ink on the substrate is not firmly bonded, and it is easy to transfer after winding, resulting in adhesion. The solution is to choose ink correctly Control the quality of ink to adapt to the substrate. In addition, the substrate surface can be treated to improve its affinity for ink, which is also a method to reduce ink adhesion. Generally, ensure that the surface tension of BOPP shall be 38 dyne

3. Main reasons and solutions: the main reasons for this phenomenon are: ① the transparency of the ink itself is poor, and the ink with good transparency should be replaced

② when printing, the solvent volatilizes too fast and the drillability is too low. Select appropriate slow drying solvent according to the requirements, and check and improve the ink drillability. ③ If the uniformity of the aluminized layer is poor, resulting in poor reflective gloss, replace the aluminized film and ensure that its surface is uniform and free of pinholes. ④ The angle of the doctor blade is too large and the printing hole is shallow. Adjust and control the angle of the doctor blade. Generally, the included angle should be controlled at about 35 degrees

4. Agglomeration of transparent ink

main reasons and solutions: this phenomenon generally occurs in the case of low temperature. In this case, the ink should be heated at room temperature of 35 ℃. In order to prevent accidents, special personnel must also be assigned to guard

in short, the imbalance of solvent ratio, improper drilling control or wrong process operation are likely to lead to many faults, so we should not be careless in every link. Therefore, when printing with transparent ink, in order to obtain the ideal effect, all links must be strictly controlled, and the appropriate ink should be selected according to the actual situation of printing

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