In packaging printing, two color printing processes are generally used, one is normal four-color printing, that is, using yellow, magenta (or magenta), sky blue and black ink overprint to copy the color manuscript; the other is spot color printing , Only use other color inks than the normal four colors to copy the original. When printing large-area background colors, spot color printing is more commonly used. If the product manuscript contains many pictures of different colors, it needs to pass the electronic color separation machine or color desktop system to scan the color separation, and then use the normal four-color printing process to produce. If the product manuscript is composed of uniform color blocks of different colors or regular gradient color blocks and text, spot color printing can sometimes be used when comprehensive consideration is given to improving printing quality and reducing the number of overprints.
The ink prepared by the spot color printing is obtained according to the principle of color subtractive color method, and the color transparency is low and the saturation is high. Spot color blocks with uniform ink colors are usually printed on the spot, and the amount of ink should be increased appropriately. When the thickness of the ink layer on the surface is large, the sensitivity of the change of the thickness of the ink layer to the color change will be reduced, so it is easier to obtain a uniform and thick printing effect of the ink color. Due to the uneven technical level of the current paper manufacturers, the color of the surface of the paper of the same specification produced will have more or less deviations, or blue or yellow, which gives the packaging and printing manufacturers the control of the product color band Here comes trouble. If the opacity of spot color patches can be used reasonably and properly, the above problems can be solved well.
The result of using four-color printing is the combined effect of subtractive color absorption and additive color mixing of dots. The color block has higher brightness and lower saturation. For light color blocks, the four-color printing process is used. Due to the low coverage of the ink on the paper, the ink color is flat and lacks a sense of solidity. Due to the angle of the dots, it will inevitably make people feel the existence of patterns. In addition, the color block printed by the four-color printing process is composed of a certain proportion of dots. When printing dots, the thickness of the ink layer must be strictly controlled. It is easy to change the color intensity due to the change in the thickness of the ink layer and the changes in printing process conditions Changes in the degree of dot expansion, resulting in color changes and uneven ink color. If the color of the color block cannot be overprinted with a multi-color machine at one time, it is also easy to cause color shift because the color of the semi-finished product is not easy to control. If sky blue and magenta are overprinted into purple, if the sky blue ink volume is large, it will be bluish, if the magenta ink volume is large, it will be red. At this time, it may be possible to change the overprint color block to a special purple version. Although there is an additional printing plate, the printing preparation time is shortened, the printing speed is increased, the hue control is stabilized, the production efficiency is improved, and the waste products are also reduced. Production costs have also been reduced. Of course, this phenomenon should be considered in the process planning.
When printing a large area of ​​light-colored uniform color patches, it is usually used to add spotting agent to the original ink to prepare spot color ink, and then perform solid printing, so that the ink layer is thicker, and it is easier to obtain the effect of uniform and thick color. If the four-color printing process is used, low-level flat-screen dots must be used, but low-level flat-screen dots are likely to be small in some parts due to tiny sand particles or poor suction during printing, resulting in small ink dots. Both. When printing, it is easy to cause too much water supply on the plate surface, paper powder accumulates on the printing plate and blanket, and the smoothness of the paper is low, which causes poor ink transfer of small dots, resulting in lighter ink color and uneven ink color, resulting in batch color difference. Increased waste.
For dark and large-area color patches, the four-color printing process may be used to superimpose several high-density dots of several colors. The ink layer is too thick and the back side is rubbed. With the spot color printing process, only one color needs to be printed, and it is not easy for the back to be dirty. With the four-color printing process, some parts of the picture and text may be synthesized from several colors, while with the spot color printing process, only one color is printed on the corresponding parts to avoid overprinting errors.
The above describes the use of spot color inks formulated with three primary colors. In fact, in packaging and printing, in addition to the ink prepared by the three primary colors, there is also an ink that people like very much-metal ink. Because of its special metallic luster, metal ink has been widely used in packaging and printing, especially in tobacco and alcohol packaging printing. The product packaging printed with metal ink is graceful and noble, which can improve the quality of the product. However, due to the low adhesion of the metal ink itself, the actual printing is more difficult than the ordinary spot ink.
There are two common metallic inks, namely gold ink and silver ink. Gold ink is made of copper-zinc alloy powder and gold-adjusting oil. The copper and zinc content in the gold powder is different, and the color of the gold ink is also different. If the zinc content is low, the color of the gold ink will be reddish; if the zinc content is high, the color of the gold ink will be greenish. At present, the gold powder (ink) sold in the market is divided into red gold powder (ink), green-red gold powder (ink), and green gold powder (ink). Silver ink is made of silver aluminum powder and silver oil. The silver powder particles are different in size, and the metallic luster produced is also different. The silver particles with large particles have strong metallic luster. Appropriately add some bright yellow, bright oil, red dry oil, dibutyl ester and other auxiliary agents in the gold and silver ink, which 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, thereby improving the printing transfer performance of gold and silver ink.
When printing gold and silver inks, there are generally two methods. One is to print the gold and silver inks first, that is, to choose inks with strong hiding power and similar to the gold (silver) inks. Gold printing ink uses light yellow ink, transparent yellow ink or fake gold ink as the base color. In order to improve the metallic luster, about 10% of gold ink can be added in an appropriate amount. Printing silver ink generally uses false silver ink as the base color. False silver ink can be prepared by diluting agent, white ink, black ink, debonding agent, No. 6 ink and white dry oil in a certain proportion. The printing adaptability of silver ink is better than that of gold ink. Only one printing can basically meet the requirements of general packaging printed products. If you encounter some large-area printed silver packaging products or use poor paper quality, you need to take two printings to show the silver gloss well. This method requires a higher level of technical skills for printing operators and is more difficult. The other is to hollow out the positions where gold and silver inks are printed on other color plates, and the gold and silver inks are printed directly on the paper. This method can be well mastered by general printing operators. Moreover, if the color used in the product plus gold and silver are four colors, it can happen to use the four-color offset printing machine to print all the colors together with the gold and silver ink at one time, thereby saving time and shortening the construction period. However, during the pre-press process planning, it should be noted that gold and silver blocks and other color blocks cannot be hard overprinted, and traps of 0.1 to 0.2 mm need to be set. In addition, it should be noted that after printing gold and silver ink, the printed product should not be rushed to dry, because the drying speed of gold and silver ink is slower than that of ordinary ink. Do not add more drying oil to the picture, otherwise the gold and silver ink particles will become thick and the ink roller Increased ink accumulation will cause adhesion of printed matter.
In short, spot color printing is a flexible and complex color printing process, which should be used properly and reasonably. In the actual production process of printing and packaging, spot colors are sometimes used alone, but often two or three colors of the normal four colors are added with one or two spot colors, and the two are used in combination. Whether to use spot colors depends on whether it is beneficial to reduce the scrap rate and improve product quality; whether it is conducive to saving time, shortening the construction period and improving production efficiency; whether it is conducive to reducing production costs and increasing corporate income. This requires the process technicians of packaging and printing manufacturers to comprehensively consider the process technology level of the factory, the skills of the operators and the use of machinery and equipment during the process planning, so as to compile a reasonable production process.
This product relates to a Sewing Machine thread rack, which mainly includes a thread passing bar, a pole for fixing the thread passing bar, a base for fixing the pole and a bedplate for fixing the base The wire rod, the pole for fixing the wire rod, the base for fixing the pole and the bedplate for fixing the base are connected with a structure that is convenient for removal and installation, so as to facilitate the overall packaging and delivery after disassembly and the installation and use of the customer The thread passing bar provided by this product has two adjacent surface thread passing holes. The surface thread passes through two surface thread passing holes and then leads to the head of the sewing machine. In this way, when cutting the surface thread on the head side of the sewing machine during the sewing process, a suitable friction force can be generated between the surface thread and the hole walls of the two holes to prevent the surface thread from falling off or sagging The product also provides the technical solution of the sewing machine thread rack with an unclosed thread passing bar, which can easily place the Sewing Thread in the thread passing hole from the unclosed opening
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