Pencils are one of the main writing instruments. Primary school students start with pencils, and printed pencils are the main type of pencils, especially for students. The lead of the pencil is the value of use, but the quality of its appearance when choosing a pencil is often one of the important indicators to measure the quality of the pencil, and it is an indispensable quality factor. The main problems in the printing of pencils are: the print pattern is blurred, the vividness is not good, the color is different, the rod is dirty and so on. In order to further improve the quality of pencil printing, it is necessary to study and explore the factors affecting the quality of pencils. Ningbo DSS Intelligent Technology Co., Ltd , https://www.dssking.com
Factors affecting the quality and aesthetics of printed pencils are various. For example, the type and production of printing plates, rubber rollers, offset plates, printing inks, pattern design and operational technology are all inextricably linked to the quality of printing. Some aspects are one-sided and inaccurate.
First, the type and production level of the printed version of the printing plate is, in a sense, one of the important factors affecting the quality of pencil printing. At present, there are three main types of printing plates used in China: copper plate, zinc plate and resin plate. The three printing plates have different lengths, and the copper plate has good wear resistance, and is easy to be made into a finer pattern. The printing is clear, the effect is good, and the service life is long, but the manufacturing cost is high. Due to its soft texture, the zinc plate is not very accurate in printing, especially printing a large area of ​​the pattern, and the service life is short, but the production cost is low. The resin plate has a simple manufacturing process and can be made in only 2 hours, and is not easy to damage the rubber roller, and the manufacturing cost is low. The biggest disadvantage is that the adhesion is poor and the use time is short. Compared with the three printing plates, the copper plate is the best, and it is advisable to consider the use of copper plate printing in places where conditions permit.
Copper plate: The printing plate is suitable for the use of copper plate. The thickness of the copper plate is required to be uniform. The thickness of the copper plate should not be too thick or too thin. The copper plate is too thick and the plate is too difficult. The copper plate is too thin and the service life is shortened. Generally, 0.8mm is used. A copper plate of a thickness is preferred. The surface of the copper plate is required to be smooth and free from scratches and unevenness.
The manufacturing method of the copper plate basically adopts the plate making method of the printing industry, and is roughly divided into three steps: the first step is photography, and the ink draft of the design pattern is photographed into a bottom plate. Before taking a photo, you should carefully check whether the draft meets the requirements, and take photos after review without any problems. When photographing, the appropriate multiples should be reduced according to the draft requirements, and the light and focal length should be adjusted to ensure the temperature of development and fixing, so that the clarity of the photographed substrate is good. The second step is to etch the plate, also known as the bad plate. Before the bad plate, the reverse side of the copper plate should be coated with paint, washed once with ferric chloride solution, and then washed once with hydrochloric acid and sodium chloride solution. . The copper plate is placed in a ferric chloride liquid at a corrosion temperature of 23 to 24 ° C, and the corrosion time is determined according to the corrosion depth. The corrosion depth should be appropriate and should not be too deep or too shallow. If the corrosion depth is too shallow, the pattern may be blurred when printed, and the copper plate may easily adhere to the ink, causing the rod to be dirty; if the corrosion is too deep, some thin lines in the pattern are easily corroded. The slope between the patterns should also be appropriate. The slope is too small to affect the service life of the printing plate. Generally, the corrosion depth is in the range of 0.35-0.4 mm. The third step is revision. Revision is one of the important links in the plate making work. The quality of the revision has a lot to do with the technical level of the revision. In the revision, you must carefully consider carefully and carefully, do not scrape off the pattern that should be left, and should not leave the extra lines that should not be left. The ones that should be removed must be scraped off so that the printed version of the printed version matches the printed version. . If there is any unclear pattern on the pattern, use a brush to fill the pattern with alkyd enamel. After the printed version is repaired, four fires (melting) are also required. The purpose of the fire is to improve the toughness of the copper plate, making it easy to bend and adjust the plate. Generally, the annealing temperature is in the range of 400 to 500 ° C, and the annealing time is preferably about 10 minutes.
Zinc plate: The zinc plate is made of metal zinc. It is made in the same way as the printed copper plate. The difference is that the copper plate is made of corrugated iron in the corrosion machine and is made by multiple corrosion. The zinc plate uses a hydrochloric acid solution as an etching solution in the corrosion machine, and a one-time corrosion method is often used. Most of the micro-crystalline zinc plates are used, the texture is relatively hard and brittle, which brings certain difficulties to the plate-setting operation, needs to be researched and improved, and adopts zinc plate materials which are more suitable for the printing plate.
Resin plate: It is a photosensitive resin plate which is widely used in the printing industry. It is made of a polymer material using a high molecular polymer. The photosensitive resin plate is divided into two types: a liquid photosensitive resin and a solid photosensitive resin. However, it is necessary to first synthesize a photosensitive resin, and then add an appropriate amount of an initiator, a crosslinking agent and the like to the photosensitive resin to crosslink under ultraviolet irradiation. Molded to make the required plate. We have tried the resin printing version ourselves, and the printing effect is not ideal. The main problem is that the resin printing plate is difficult to bend to form the shape and size corresponding to the plate seat. The center line of the printing plate and the center of the plate are difficult to be aligned. The four-color printing plate is difficult to align the color, which is prone to color deviation and directly affects The quality and effect of the printing; the adhesion to the printing ink is poor, and when the pattern is larger, the coloring of the printing is uneven. We have also discussed why the resin printing industry is widely used in the paper printing industry, and it is not suitable for pencil printing. According to preliminary research, the paper color printing machine is bulky and the seat is cylindrical. The printed version is easy to install and use, while the pencil printing machine is small and curved, making it difficult to install and position. There is also a major disadvantage of the resin printing plate, that is, the crosslinking agent used in photocrosslinking contains a hydrophilic group, so that the printing plate has a certain hygroscopicity, so moisture absorption should be avoided during storage; in order to prevent further crosslinking and curing of the photosensitive resin plate, Should be kept away from light.
Second, the rubber roller is also called the ink roller. There are two main types of rubber rollers used in pencil printing machines, namely rubber rollers and polyurethane plastic rubber rollers.
The rubber roller is made of natural rubber and added to the auxiliary agent. After being ground and dispersed by a three-roller machine, it is vulcanized into a rubber roller in the mold. Rubber rolls are mostly used in the pencil industry. Its advantage is that the natural rubber roller processing is easier than the urethane rubber roller and has good recycling performance. If it is found that there are rubber roller injuries, scratches and unevenness during use, it can be used for grinding within a certain size range. However, its disadvantage is that the elasticity is poor and the wear resistance is not as good as that of the urethane rubber roller.
Polyurethane rubber roller, also known as plastic rubber roller, is a synthetic rubber, a polyester formed by condensation of a dihydric alcohol and a dibasic acid, and then condensed with a diisocyanate to form a high polymer. The use of a polyurethane resin roller in a pencil printing has many advantages compared with a natural rubber roller, and the polyurethane rubber roller has high abrasion resistance, good elasticity, and good ink guiding property. Therefore, it is preferable to use a polyurethane rubber in a pencil printing. However, this rubber roller is sensitive to dimethyl phthalate reaction, and it is prone to cause uneven expansion of the surface of the rubber roller due to long-term contact with dimethyl phthalate, which may cause unevenness of the surface of the rubber roller, affecting the printing quality and effect. Therefore, in the process of ink preparation and ink adjustment, the ratio of dimethyl phthalate should be reduced, and the amount of dibutyl phthalate should be increased to alleviate the above phenomenon. In addition, urethane rubber components contain toxic raw materials, which should be noted in the selection and use.
Third, the offset plate is one of the main tooling parts of the printing machine. The printing ink is transferred to the offset plate through the rubber roller, and then the printing pattern is transferred onto the surface of the pencil through the offset plate. The quality of the rubber sheet directly affects the quality of the printing. Therefore, when selecting the offset plate, attention should be paid to the use of the offset plate, no shortage of defects and unevenness, and good solvent and oil resistance. Since the offset plate is directly in contact with the ink, if the offset resistance of the offset plate is not good, the solvent may easily cause swelling and bulging on the surface of the offset plate, so that the printing pattern cannot be accurately printed, or the pattern pattern is defective, and the pattern is lost. The integrity and visibility of the nitrile rubber version is generally preferred.
Fourth, the pattern design The pattern of the printed pencil is colorful and varied. Therefore, it is both a cultural product and a craft art. The overall requirements of the printed pattern are: clear pattern, bright colors, beautiful appearance, novel and lively, integrating aesthetics, visibility and decoration. Whether the design of the printed version is novel and beautiful is closely related to the aesthetic and aesthetic quality and design level of the art designer. The steps in the design of the print pattern are to first design a four-color color draft, and then draw a color separation ink draft. The following principles should be mastered when designing the print pattern:
First of all, we should meet the needs of consumers at all levels and adapt to the psychology of customers. Printed pencils are divided into three levels: medium, low and high. The main consumer of middle and low-grade printing pencils is primary and secondary school students. The design should be based on their psychological characteristics, mainly in the form of animals, flowers, cars, airplanes, ships, etc. The colors should be red, pink, blue and green as the main tone. The main consumer object of high-grade printing pencils is for the office, enterprises and institutions to use the office, requiring elegant and solemn patterns, such as bamboo leaves, drawing strips or monochrome. The color should be dark green, dark blue, and purple red. Avoid red and green.
Secondly, it has the atmosphere of the times and adapts to the trend of the times. As early as in the 1980s, Aberdeen, Tang Laoya and other well-known cartoon characters were very popular among children. Where the sea is raging, Sun Wukong’s troubles such as the Heavenly Palace and Snow White are also greatly appreciated by the children. The image and pattern of the Olympic Games Fuwa is currently the idol of children. Art designers should give full play to their own ingenuity and design, and design prints that meet the children's psychological needs, novel and bright, bright colors, and children's favorite music, will be favored by children.
Third, for export products, we must effectively understand and master the customs and customs of the countries and regions. For the export of printed pencil pattern design should fully respect the customs and hobbies of the other country, for example, some countries in the color of taboo yellow, some taboo blue. The same is true for the design of the pattern, which requires the art designer to be familiar with and master these situations, not to be wishful thinking, to be self-respecting, and to design prints according to the needs of customers.
Fourth, the use of thin lines should be used as much as possible in the design of printed patterns, avoiding the use of large areas of thick lines. Many years of practical experience has proved that the use of thin line patterns is better, and the use of thick line patterns is prone to unevenness in the same color, and even color defects, the printing effect is not ideal. Art designers should make ingenious ideas and designs according to the small size of the pencil printing pattern, and the ideal effect can be achieved.
V. Printing inks Domestic pencil printing generally uses special inks composed of nitrocellulose as the main film-forming substance and volatile solvent. It requires the ink to have strong adhesion, good hiding power and fast drying speed, so that it has good decorative and protective effects. The difference between pencil printing ink and nitro pencil paint is that it uses a high boiling point solvent, has a higher viscosity, and is slower to volatilize than nitro pencil paint. Most of the larger pencil companies in China produce their own inks. The main raw materials of the ink are 1/2 second nitrocellulose, butylene--T anhydride resin, dimethyl phthalate, dibutyl phthalate and various colorants. In the formulation design, the difference of climate and air humidity between the south and the north should be considered. When formulating the resin liquid in the north, the dibutyl phthalate-dissolving resin with a slower volatilization rate is generally used. In the choice of pigments, generally, the color is bright, the fineness is high, and the oil absorption is relatively low and the dispersion is relatively uniform. Usually, it is mainly made of phthalocyanine and lightfast.
In the preparation, generally, the base material, that is, the color developing agent (nitrocellulose pulp) and the resin liquid, should be prepared, and then the printing ink is prepared. The formula in the north is:
The formulation of the color developing agent is: 1/2 second nitrocellulose lkg, dimethyl phthalate 3kg, and dissolved into a transparent viscous liquid by stirring.
The formulation of the resin liquid was 30 g of maleic anhydride resin and 70 g of dibutyl phthalate, and the mixture was heated and dissolved to form a resin liquid.
The formula of the printing ink is shown in the table below. The purpose of this formula is to introduce the jade. The enterprise can explore and improve the ink formula according to its actual situation and the development of domestic pigments and dyes.
; printing ink reference formula; ; color developing agent; resin liquid; red powder; phthalocyanine green; phthalocyanine blue; high pigment carbon black; light yellow red 62; 13;
Blue 65 ; ; 10 25
Yellow 65 ; ; 10 ; ; 30
Green 70 ; ; 10 ; 20
Black 70 ; ; 15 ; ; 15
Note: The numbers in the table are percentage (%)
In the formulation of printing inks, pigments are generally used, and dyes are rarely used. Because pigments have large hiding power, strong coloring power, good light resistance and weather resistance, they are widely used in printing inks. Although the dye has the characteristics of bright color and good transparency, its hiding power, tinting strength and light resistance are far less than those of pigments. Therefore, in the past, dyes were only used in high-grade printed pencils and drawn pencils, and rarely used in low-end printed pencils. In the method of use, the dye is usually dissolved in an alcohol-soluble solvent, and then uniformly mixed with the varnish to be used as a varnish. Whether it is possible to expand the scope of use, pencil manufacturers can further experiment and explore in practice. The dyes commonly used in pencil printing are mainly alcohol-soluble dyes, mainly alcohol-soluble, red-resistant, sun-resistant, red, sun-resistant, sun-resistant, sun-resistant, sun-resistant, and sun-resistant.
Printing ink printing:
Its operation is relatively simple. Firstly, the prepared nitric acid pulp (developer), maleic anhydride resin liquid and pigment are prepared according to a certain formula ratio, and then ground 10 to 12 times by a three-roll mill. It can be a viscous printing ink. When rolling the ink, the spacing of the rolls should be properly adjusted, and the number of rolling rolls cannot be reduced arbitrarily. The toner, the resin liquid and the color materials are sufficiently mixed uniformly, the pigment is sufficiently dispersed in the color developing agent, and the printing ink is reached. The required fineness.
Sixth, the first problem encountered by the color printing operator of the printing ink during the operation is the ink coloring. The so-called printing ink coloring refers to the color of the ink required to be correctly selected according to the color draft designed by the artist. The ink coloring work must master the basic knowledge of color grading and have certain practical experience. For the color draft, the pigment contained in the color can be correctly distinguished. Otherwise, the color and color of the ink and the color of the design draft will have a certain gap. The color of the ink and the color of the printed pattern are far apart, even in the north. Can not achieve the desired effect. Attention should be paid to the following problems when coloring printing inks.
1. First of all, we must master the basic knowledge of color grading. The colors of colors are various, but the most basic ones are three colors, namely red, blue and yellow. All colors are made up of these three colors, commonly known as the three primary colors. The color change after the blending can be seen from Fig. 1.
The combination of the two primary colors gives a complex color, and the other primary color corresponding to it is a complementary color. The primary color and the complementary color can be diluted with white to make the color tone lighter, and the same color can be used to obtain different shades. For example, blue added white can turn into light blue, sky blue; red can be turned into white, red, pink; yellow can be turned into white, yellow, etc., color matching color as shown in Figure 2.
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The printing operator must firmly grasp and be familiar with the basic principles and methods of these toning to accurately call out the desired color and tone.
2. When grading, you should pay attention to the amount of the amount of ink added to each color, and generally adopt a gradual increase. For example, when blending pink ink, it should be based on the difference of pink shades of pink, and gradually add pink to the same color as the tone color.
3. It is very important for the printing operator to grasp the coloring rule of the printing ink. It is very important to accumulate the coloring experience. It is the necessary condition and the basic function of the operation to quickly and accurately call out the required color and color.
4. For the color and color that can't be adjusted, please ask the art designer for assistance. However, some colors, for example, commonly known as capsicum red, were formulated with cadmium red. Because cadmium is a heavy metal, it cannot be used in printing inks. Therefore, art designers should avoid using such raw materials to draw color drafts when designing color drafts, or use new pigments instead.
7. Whether the printing operation printing operation is proper, there is a process from printing the printing plate to printing the qualified printing pencil. The length of the plate change and the quality of the print are closely related to the skill level and responsibility of the operator. Using the same ink and the same print plate, this is common in the same amount of time. Therefore, it is necessary to grasp several key points of operation when printing, in order to achieve good and fast from changing plates to printing.
1. When printing the plate, be sure to check the center line on the copper plate and the center line on the plate. This step is done. It is much easier to adjust the plate. After the plate is printed, it should be fixed with screws. Loose. Otherwise, it is easy to run the version during the test run, and the printed version may be damaged. After the copper plate is good, the four printing plates should be adjusted in accordance with the requirements of the design draft. The length of the word should meet the requirements.
2. Before printing, adjust the pressure of the printing plate and the offset plate. If the pressure is too large, the ink on the offset printing plate is too heavy, and the printed pattern is incomplete, and the ink color is too light. The pressure of the printing plate and the offset plate should be clear and the non-stick ink should be used.
3. In the process of trial printing, if it is found that the partial pattern cannot be printed or printed, it may be considered to adopt a relatively stupid, but applicable method, that is, a thin and thick piece of paper on the offset plate can completely achieve the desired printing. effect.
4. Whether the amount of ink in the ink fountain is suitable is one of the important factors affecting the uniformity of the printing ink. It is very important to adjust the amount of ink in the ink fountain when the surface of the deinking roller is not flat and needs to be processed or replaced. If the ink fountain is too loose, the amount of ink is too much, the printed color is very deep, the ink is very dry, and the printing plate and the offset plate are easy to stick to the ink, causing the printing pattern to be blurred. If the ink fountain is adjusted too tightly, the ink color after printing is too light, and the printing color is not bright, dull and dull. Therefore, the ink amount of the ink fountain should be adjusted to be loose, not sticky, and not too shallow, so that the ink is uniformly transmitted to the ink roller.
5. The pressure between the ink roller and the printing plate and the pressure between the offset plate and the pencil also have an important influence on the quality of the printing. If the pressure is too large, not only the ink roller is easy to wear, but also the printing plate is easy to stick to the ink, resulting in an unclear pattern. If the pressure is too small, the ink on the printing plate is too little or not, and the pattern cannot be printed or printed. Therefore, adjusting the pressure between the ink roller and the printing plate is one of the important steps in the printing operation. At the same time, pay attention to adjust the pressure between the offset plate and the pencil, so that the pattern on the printing plate is completely and accurately printed on the pencil to make a beautiful and elegant printing pencil.