Paper Box external image is the factor that determines whether others make a purchase, so how can we not reduce the quality of packaging and printing when printing color boxes at Xinqicai Printing Factory? Today we will share that affect the quality of color box printing.
The external image of products is becoming increasingly important in the fierce market competition, and color boxes have become an excellent choice for packaging the external image of products due to their high-end, exquisite, and beautiful appearance.
Folding Paper Box color boxes are not only lightweight, easy to carry, with a wide range of raw materials, but also have excellent environmental protection.
How to improve the printing quality of color boxes?
*The influence of film
The development and fixation process of film after exposure directly affects the clarity and contrast of the image on the film. Therefore, for plate making films, the key is to consider the density of the graphic and textual parts, as well as the contrast between the graphic and textual parts and the non graphic and textual parts. The higher the density and the greater the contrast, the better the quality of the plate making film, and the quality of the printing plate produced with it can be guaranteed. In addition, the thickness of the plate making film base also has an impact on the plate making quality, and generally thin film has better results than thick film.
*The impact of plate printing
During the plate printing process, the intensity of the light source, the distance between the light source and the plate material, and the length of exposure time can all affect the quality of the plate printing. Strong light source, short distance, and relatively short exposure time; Weak light source, long distance, and relatively long exposure time.
Under a certain light source and distance, as the exposure time increases, the decomposition of the visible part of the film intensifies until the visible part of the film completely decomposes. If the exposure time continues to increase, the edge of the photosensitive film on the part where no light is visible will gradually decompose due to the radiation of strong light, resulting in thinner, even broken, and burnt lines in the printed plate graphics and text. If the exposure time is insufficient, the non graphic and textual parts of the film may not fully decompose, and the non graphic and textual parts of the plate may still have the film after development, which may cause dirt during machine printing.
In addition, the exposure time required for different brands of printing plates also varies, which must be noted by people. In addition, the degree of adhesion between the film and the printing plate during vacuum printing also affects the quality of the printing plate. If the adhesion is not solid, the printed plate may have problems such as ghosting and unclear mold burning.
*The impact of development
The concentration of developer solution is too high and the development is too fast, which can easily cause excessive development of the printing plate, thinning of graphic and text lines, loss of small dots or unclear graphic and text, and affect the quality of color box printing; The concentration of the developing solution is too low, making it difficult to clean the drug film surface when exposed to light, and making it easy to dirty the plate when printing on the machine.
Development time: If the development time is too long, the drug film surface of the printing plate without visible light is easily dissolved, and the printing plate images and texts will become lighter and thinner, resulting in inaccurate and unclear prints during printing; If the development time is too short, it is difficult to completely remove the drug film surface decomposed by light, and it is easy to get dirty during printing.
The appropriate development time is when the plate is developed and rinsed, and the photo decomposed film surface is just rinsed clean. If the concentration of the drug solution is relatively high, the development time should be shortened accordingly; On the contrary, the development time should be correspondingly extended.
*The impact of ink transfer
The printing process is actually the process of ink transfer. Generally speaking, the ink transfer rate of offset printing is relatively low, about 38%. After the printing plate is inked and comes into contact with the rubber cloth, the ink transfer rate is about 50%. When the rubber cloth comes into contact with the paper again, the ink transfer rate is about 76%. Therefore, controlling the transfer rate of ink is crucial.
Ink adaptability, ink balance, performance of printing plates and rubber fabrics, as well as paper and printing machines, all affect the transfer of ink.
*The influence of ink performance on ink transfer
Ink with low viscosity and high fluidity is easy to transfer and has a high transfer rate; Ink with high viscosity and low fluidity has a low transfer rate. To improve ink transfer rate, it is necessary to control the viscosity and fluidity of the ink.
The performance of ink will also vary with environmental changes. When the temperature is high, the ink viscosity is lower, and when the temperature is low, the ink viscosity is higher.
In actual production, different models, types, and drying methods of inks should be selected according to the actual situation. In addition, adding an appropriate amount of ink blending oil to the ink can adjust the ink performance, which is beneficial for controlling dot size and improving ink transfer rate.
*The influence of rubber blanket performance on ink transfer
Rubber blanket must have good ink absorption and transmission properties, as well as characteristics such as oil resistance, acid resistance, alkali resistance, and good elasticity.
If the rubber blanket is not thoroughly cleaned after printing, the ink remaining in the fluff will slowly harden the conjunctiva, causing damage to the fluff like structure on the surface of the rubber, directly affecting the ink absorption rate of the rubber blanket, thereby reducing the ink transfer rate of the rubber blanket.
Therefore, after printing is completed, the rubber cloth should be thoroughly washed clean. If the downtime is relatively long, a layer of pumice powder can be applied to its surface to maintain the original fuzzy structure of the rubber cloth, and ensure that the rubber cloth has good ink absorption and transmission properties.
*The impact of paper suitability
The suitability of paper is mainly reflected in aspects such as smoothness, whiteness, and stiffness. Paper with high smoothness requires relatively less ink; Paper with poor smoothness requires a relatively large amount of ink.
During the printing process, different types of paper require varying amounts of ink depending on their surface conditions. Under the same variety, quantity, and price conditions, paper with higher smoothness and whiteness has better printing quality than paper with lower smoothness and whiteness.
*The impact of plate suitability
The quality of the base sand of the printing plate, the hydrophilicity of the metal plate, and the hydrophilicity of the coated polymer resin film surface are related to the suitability of the printing plate, affecting ink transfer and ink balance of the plate. During the
Corrugated Box plate making process, the quality of exposure and development can also affect the performance of the printing plate.
*The impact of ink wash balance
Ink balance is a relative balance, not an absolute balance. During the high-speed operation of the equipment, the graphic and non graphic parts of the printing plate are both inked and watered, and there is mutual infiltration, which inevitably leads to ink emulsification on the printing plate.
If the amount of water and ink is not well controlled, it will inevitably deepen the ink emulsification, leading to burnt and dirty plates in printing. When printing, the usual method is to reduce the amount of water and increase the amount of ink appropriately, but sometimes it may also decrease the amount of ink.
In addition, ink emulsification will vary with changes in environmental conditions. In actual printing production, it is necessary to control the ink viscosity and pH value of the fountain solution according to the actual situation, and control the amount of ink and water. The standard is to ensure that the printing plate is not burnt or dirty.
*The impact of printing pressure
Printing pressure refers to the interaction force between the printing plate cylinder and the rubber cylinder, as well as between the rubber cylinder and the embossing cylinder, which is a necessary condition for ink transfer.
The printing pressure is too low, making it difficult to transfer ink, resulting in light and blurry ink marks; Excessive printing pressure causes ink to expand towards non graphic parts, resulting in severe dot enlargement and image distortion. At the same time, it is also easy to reduce the printing resistance of the printing plate and rubber cloth.
Therefore, it is necessary to adjust the mechanical pressure correctly. Different quantities of paper require different printing pressures, and only with appropriate printing pressures can the ink color be uniform and light.
