Analysis of Application of Spot Color Printing in Packaging Industry

At present, economic globalization has become an irresistible trend in world development. Accompanied by the accelerating pace of economic globalization, China has already reached the threshold of the WTO. After China's entry into the WTO, China's economic development will face greater challenges and challenges from economic globalization. Economic globalization is actually a global market economy. Since it is a market economy, there is an objective law that cannot be tampered with: Opportunities and risks are common, and opportunities are often born of risk. After joining the WTO, the Chinese packaging industry will face what kind of situation, how to grasp the "WTO entry" to China's packaging industry development opportunities, promote the optimization and upgrading of the packaging industry structure and improve the quality of packaging companies, and how to deal with China's packaging after joining the WTO The challenges brought by industrial development will be a major issue for how China's packaging industry can better survive and develop in the reform and opening up in the new century.

At the same time, with the development of the market economy and the improvement of people’s living standards, manufacturers in the packaging industry are gradually moving towards industrial scale production. Consumers are increasingly demanding the appearance quality of product packaging, and are pursuing the appearance and performance of products. Has become a trend. Based on this, a good package can beautify the product, and unsatisfactory packaging can have a counterproductive effect. The aesthetics of packaging are closely linked to the product's own value. In order to better stimulate the consumer's vision and stimulate their desire to buy, many manufacturers now like to use a large area of ​​color to carry out product packaging design. In particular, domestic cigarette and wine packaging design is more like the application of a large area of ​​red and yellow blocks, a large area of ​​gold and silver blocks. However, to achieve product packaging to meet customer expectations, the packaging industry manufacturers need to pay close attention to the actual application of spot colors in their production process, so as to avoid the production of products that do not meet the desired effect of the customer, resulting in customer complaints, complaints and returns Compensation, even loss of supply.

Spot color printing is characterized by a large area of ​​real-time color patches, shelf display effect is good, reducing the color dots due to dot overprint, dot distortion, color stability, easy identification.

For packaging and printing manufacturers to use spot colors correctly and reasonably, they need to understand the color rendering principle and several concepts (color light primary colors, three primary colors of color materials, color light additive methods, and color material subtractive methods). Only by being aware of the principles of color can we reasonably control the use of color in the printing process. According to the characteristics of physical stimuli of light, the visual physiological characteristics of human beings and the results of a large number of chromatic light mixing experiments show that the three monochromatic lights of red, green, and blue light are mixed in different proportions, and all other shades of light can be obtained. Neither can be mixed by any other color light, so red light, green light, and blue light are determined as the color light primary colors. The method of new color light obtained by mixing two or more color lights is called color light coloration. The new color light is brighter than any of the color lights involved in the mixing, and the color light addition method follows the principle of increasing lightness. By mixing the three primary colors of light at different ratios by the color light additive method, all the natural colors can be produced. Pigment refers to a material that has its own color and can color other objects. The colorant is a non-luminous body, the color of which depends mainly on the reflection (or transmission) of its absorption of light from the outside. The three primary colors of the colorant are yellow, magenta, and cyan, which are complementary colors of the three primary colors of blue, green, and red, respectively. The yellow colorant can absorb blue light in white light, transmit or reflect red light and green light in white light, magenta color material can absorb green light in white light, transmit or reflect red light and blue light in white light, cyan color material can absorb The red light in white light transmits or reflects blue and green light in white light. The color subtractive method refers to the phenomenon that two or more kinds of color materials are mixed to obtain a new color. Based on the three primary color materials, according to different proportions, they can be blended into all other colors. The three primary color materials cannot be mixed and prepared with other color materials. The essence of the color subtractive method is to increase the number of times that the color material is selectively absorbed, so that the color light energy is weakened, and then the brightness is reduced and the color is dark when the color changes. Printing and packaging manufacturers generally use yellow, magenta (or magenta), and sky blue inks instead of yellow, magenta, and cyan in the three primary colors of the colorants.

In packaging printing, two color printing processes are generally used. One is normal four-color printing, which refers to a printing process that uses yellow, magenta (or magenta), sky blue, and black ink overprinting to reproduce various colors of colored originals. The other type is spot color printing, and the printing process of copying the color of the original is performed using only other colors other than the normal four colors. It is more common to use a spot color printing process to print a large area of ​​background color. If the product manuscript contains many pictures of different colors, it needs to be scanned and separated by an electronic color separation machine or a color desktop system, and then produced by a normal four-color printing process. If the product manuscript is composed of regular color patches with uniform color patches of different colors and regular gradient patches and texts, it is sometimes necessary to use spot color printing in consideration of improving the printing quality and reducing the number of overprints.

The ink that is prepared by spot color printing is obtained according to the principle of subtractive colorants, and its color has lower brightness and higher saturation. The uniform color block of ink is usually printed in the field, and the amount of ink is appropriately increased. When the thickness of the ink layer is large, the sensitivity of the ink layer thickness changes to the color change will be reduced, so the ink color is more easily obtained. Thick printing effect. Due to the uneven technical level of the current paper manufacturers, the color of the same specification paper surface will appear more or less deviation, or partial green, or yellow, which gives the printing and packaging manufacturers control products. The color brings trouble. This kind of strong opacity feature can be well solved if it can reasonably and properly utilize the spot color patches. The use of four-color printing results in the combined effect of subtractive color absorption and additive color mixing of the dots, and the color block has a higher brightness and lower saturation. For light-colored blocks, a four-color printing process is used. Due to the low coverage of the ink by the ink, the ink is bland and lacks a solid feeling. Because of the network point of view, it will inevitably make people feel the presence of patterns. In addition, the four-color printing process overprints the color blocks, because the various colors that make up the color blocks are mostly composed of a certain percentage of dots. When the printing dots are printed, the thickness of the ink layer must be strictly controlled, and the thickness of the ink layer is liable to change. Changes in the printing process conditions cause changes in the color intensity and the degree of dot enlargement, resulting in a color change. Furthermore, since any color change that composes the color block will cause the color of the color block to change, and the chance of occurrence of uneven ink will multiply, the color blocks overprinted by the four-color printing process are not easy to obtain ink color. Uniform effect. If the color of the color block cannot be overprinted with a multi-color machine at one time, color shift may easily occur due to the uneasy control of the color of the semi-finished product. If the sky blue and magenta are overprinted into purple, if the sky blue ink is large, it will be bluish. If the magenta ink is large, it will be reddish, which will cause great trouble to the machine operator. If the operator's level is not very high, then the printing The products that come out may be varied, with several colors. At this time, it is advisable to change the superimposed color blocks to a special purple version. Although there is one more edition, the printing preparation time is shortened, the printing speed is increased, the hue control is stabilized, the production efficiency is improved, waste products are also reduced, and the overall production is counted. The cost has also decreased. Of course, this phenomenon should be taken into account when planning the process.

In addition, when printing a large area of ​​light-colored uniform color blocks, it is common to add a diluting agent to the original ink to prepare a spot color ink, and then perform field printing so that the ink layer is thicker and the color uniform and thick effect can be easily obtained. If a four-color printing process is used, a low number of flat screen dots must be used. However, low-level flat screen outlets are liable to be caused by tiny sand particles or slightly poor suction resulting in small dots in individual parts during the printing process, resulting in uneven ink, and excessive water supply due to printing on the printing surface. Stacking on the blanket, low paper smoothness, etc. cause poor dot transfer of the ink in the small dots, thereby causing the ink to become lighter and the ink color to be uneven, which in turn causes a batch color difference, which increases the scrap. For a dark, large-area color patch, a four-color printing process may require superposition of high-number dots of several colors. The ink layer is too thick to have a back stain; for spot color printing, only one color is printed. , it is not easy to appear dirty on the back. With the four-color printing process, some parts of the graphic text may be synthesized by several colors, while the spot color printing technology is used, and the corresponding parts only print one color, which avoids the possibility of overprinting errors.

The above is the use of spot color inks formulated with three primary colors. In fact, in the packaging and printing, in addition to the three primary colors and inks, there is a kind of ink that people like very much. It is metal ink. Because of its special metallic luster, metallic ink has been widely used in packaging and printing, especially in cigarette packaging and printing. The merchandise package printed with metallic ink is elegant and elegant, which can improve the quality of the product itself. However, since the adhesion of metal ink itself is not strong, in actual printing, the difficulty is also greater than the ordinary spot color ink.

There are two kinds of common metallic inks, namely gold ink and silver ink. Gold ink is made of copper-zinc alloy powder and gold oil. The content of copper and zinc in gold powder is different, and the color of gold ink is also different. The zinc content is low, the gold ink is reddish; the zinc content is high, and the gold ink color is partial green. At present, gold powder (ink) sold only on the market is divided into red gold powder (ink), green gold powder (ink), and green gold powder (ink). The silver ink is made of silver aluminum powder and silver adjustment oil. Different silver powder particles have different metallic luster, and the coarse silver particles have stronger metallic luster. Appropriate addition of some bright yellow, bright oil, red dry oil, dibutyl ester and other auxiliary agents in the gold and silver ink can enhance the affinity, viscosity and fluidity of the gold and silver ink, so that the adhesion performance of the gold and silver ink is obtained. Improve and improve the print transfer performance of gold and silver ink.

When printing gold and silver ink, there are generally two ways. One is to print gold and silver ink first. That is, the ink with the strong hiding power and similar color to the ink of gold (silver) ink is used. Gold ink is used with pale yellow ink, clear yellow ink or fake gold ink to create a background color, and about 10% of gold ink is added in order to increase the metallic luster. Yinyin ink generally uses fake silver ink to make the background color. False silver ink can be prepared by diluting agent, white ink, black ink, de-sticking agent, No. 6 varnish, and white dry oil. The printing ink of silver ink is better than gold ink, and it can basically meet the requirements of general package printing with only one printing. If you encounter some large-area silver packaging products or use poor paper, you need to take two prints to be able to show a good silvery luster. This method requires a high level of technical skills for printing operators and is relatively difficult. The other is to hollow out the position of gold and silver ink on other color plates. The gold and silver ink is directly printed on the paper. This type of general printing operator can print well. Moreover, if the colors used in the product plus gold and silver are four colors, it is possible to use a four-color offset press to print all the colors including gold and silver ink at one time, thereby saving time and shortening the construction period. However, in the prepress process planning, we must pay attention to not allow gold and silver blocks and other color blocks hard overprinting, need to set 0.1-0.2 trapping, so as to avoid the error of the machine due to the printing paper leakage of paper color, thus affecting the appearance. Another thing to note is that after printing gold and silver ink, do not rush to dry because the drying speed of gold and silver ink is slower than that of ordinary ink. Do not add more dry oil, otherwise the gold and silver ink particles will become thicker. There are also many ink deposits on the roller, which will cause the adhesion of the printed product.

In short, spot color printing is a flexible and complex color printing process involving many factors. Currently, it has been widely used in the packaging industry. However, in order to obtain suitable application effects, manufacturers in the packaging industry must be appropriate and reasonable. For use. In the actual production of the modern packaging industry, spot colors are sometimes used on their own, but in many cases two or three of the normal four colors are used in combination with one or two spot colors. Whether or not to use spot colors depends on whether it is beneficial to reduce scrap rates and improve product quality; is it beneficial to save time, shorten the construction period, and increase production efficiency; is it not conducive to reducing production costs?