Post press processing of the hottest aluminum plat

Post press processing of aluminum plate printing

the substrate of aluminum plate printing is aluminum plate. Because the adhesion of printing ink on the surface of aluminum plate is low, and the aluminum plates collide and squeeze with each other during transportation, it is very easy to destroy the overall effect of printing patterns, and then seriously affect the quality of printed aluminum plate, so the post press processing of aluminum plate printing is particularly important. This paper analyzes the glazing and packaging of the two key processes of aluminum plate printing and post press processing, and discusses the essentials and precautions in the implementation process

first, glazing

glazing, also known as varnishing, is to coat a layer of varnish on the surface of the printed pattern (just like a protective cover, so it is vividly called varnishing) in order to enhance the adhesion of the ink and protect the printed pattern from hard objects. After the printing aluminum plate is polished, the hardness of the printed pattern surface is significantly improved (up to 4h pencil hardness), the brightness of the printed pattern is also enhanced, and the visual effect is more ideal. However, if the glazing operation requirements are not properly mastered, the four coal cities in Jixi, Hegang, Shuangyashan and Qitaihe in Heilongjiang are facing great transformation pressure, and the negative impact of products cannot be underestimated. The following mainly analyzes the relationship between glazing and the hardness and brightness of printed matter, the color change of printed aluminum plate after glazing, the impact of coating machine material rejection on the product during glazing, and the impact of corner board on the quality of polished printed aluminum plate

1. hardness and brightness of printed aluminum plate after polishing

the varnish used for printed aluminum plate is thermosetting, that is, it must be cured by heating, so the hardness of printed pattern after polishing is different from _, It is directly related to whether the oil can be completely cured during baking. The hardness test method is tested in accordance with the national recommended standard "pencil determination of film hardness" GB/t6739 1996, in which "pencil determination of film hardness" is divided into two test methods: testing machine method and manual method. Materials and instruments used in the testing machine method: a group of Zhonghua brand advanced drawing pencils (9h, 8h, 7h, 6h, 5h, 4h, 3h, 2h, h, F, Hb, B, 2b, 3b, 4b, 5b, 6b, of which 9h is the hardest, 62. Evaluation of "dynamic conflict" B is the softest), Great Wall brand advanced drawing eraser, 400 water sandpaper, pencil sharpener, pencil hardness tester. The material used in the manual method is the same as that of method a, but there is no pencil hardness tester. Manual inspection is usually used, and the detection instrument is simple and easy to operate. The hardness of printed aluminum plate shall not be less than 4H pencil hardness. During the test, it was found that the hardness of the same varnish was also different when it was baked at different temperatures. Within the range that the varnish is allowed to bake, Wenhao Xubo high gloss has good hardness, and different varnish has different optimal curing temperature. Therefore, different baking temperatures must be adopted according to different varnish during production to avoid the product failing to meet the hardness requirements due to blindly setting the same temperature

the brightness of printed aluminum plate after polishing is related to the film thickness of varnish. The so-called film thickness refers to the dry film weight of varnish or coating cured per unit area, which is usually expressed in g/㎡. Advanced film thickness gauge or simple and practical plate can be used for film thickness measurement in production. The measurement of the measuring plate is to use 10cm 10cm aluminum sheet coated with varnish or paint, and use the weight of the baked aluminum sheet minus the weight of the aluminum sheet not coated with varnish or paint, and then multiply it by 100, that is, the film thickness. In a certain range, the higher the inner film thickness of glazing products, the brighter the printed matter, but the corresponding cost will also increase. Therefore, manufacturers should pay attention to the control of film thickness, which should not be too low (too low printing products have no brightness) or too high (high cost will make manufacturers almost no profit). Taking Guangdong Baiyun bv8290 varnish as an example, it is suggested that the film thickness should be controlled within 2G/㎡ ~ 3G/㎡

2. Pay attention to the color change of printed aluminum plates after e-light baking

after some printed aluminum plates are polished and baked, the color of printing patterns changes, especially the spot color ink that is prepared is the most common. There are two main reasons for discoloration, one is the discoloration of ink, the other is the discoloration of varnish, and the degree of discoloration of different varnish is different. Therefore, the production process color card should include the printing samples before glazing and the printing samples after glazing as a reference before glazing. If the varnish used for glazing is replaced, a prenatal test should be carried out to confirm the influence of the varnish on the color of printed aluminum plates, so as to achieve prenatal mastery; In production control to minimize the influence of varnish on the color of printed aluminum plate

3. Coating machine material rejection in the glazing process affects the quality of printed aluminum plate

at present, coating machine is usually used for glazing of printed aluminum plate. The cots coated with varnish move in a circular motion, and the centrifugal force tends to make the varnish separate from the cots. Routine inspection during glazing: if the staff of elongation at break, shrinkage and recovery do not operate properly, it is easy to cause the glazing oil to be thrown onto the printed aluminum plate in strips, and highlight the plane of the printed aluminum plate after baking and curing, affecting the appearance effect of the printed aluminum plate. Therefore, it is necessary to ensure the normal operation of the equipment and check the operation of the equipment at all times during the production process

4. The putty adhered to the surface of aluminum plate printing affects the product quality

angle inserting plate is that when aluminum plate printing is polished and baked, one corner of aluminum plate is inserted into the flower iron frame due to the incorrect conveying posture of aluminum plate. The gusset plate will stir the dust deposited at the bottom of the oven. The microcomputer controlled pin disc friction and wear tester can be used for ball disc or pin disc experiments to make the dust adhere to the varnish that is not fully cured. After complete curing, black impurities form on the surface of aluminum plate prints, resulting in unqualified products. Therefore, in the process of polishing, a special person should be assigned at the inlet of the oven to check the conveying state of the aluminum plate, and inspect whether there is a corner board at the accumulation at the tail of the machine. If there is any, stop the machine in time for inspection and take remedial measures

II. Packaging

the packaging requirements of aluminum plate prints are relatively strict, because the aluminum plate is soft, easy to deform, and easy to be scratched. Unqualified packaging will cause quality defects such as scratches and bumps on the surface of aluminum plate prints, so the packaging should be designed according to its nature. There are strict requirements for the packaging weight and packaging method of aluminum plate printing products. Only by complying with the corresponding requirements can we ensure that customers are very satisfied with the quality of printed aluminum plates after the products are delivered to customers

1. the weight of packaged products requires that the aluminum plate is metal, and the aluminum plate per unit volume is heavy, which requires that the weight of each package should not be too large, otherwise the package cannot bear it. The weight of large package shall not exceed 500kg, which will cause the aluminum plate to slide and form friction scratches

2. The printed aluminum plate in the packaging method is very easy to be scratched and scratched, affecting the product quality, and causing return in serious cases. Therefore, according to the transportation distance and slippery degree of the product, the following three kinds of packaging are formulated

(1) ordinary printed aluminum plate, short-distance transportation (within 100 kilometers): smooth wooden support plate is used at the bottom to prevent the aluminum plate from deformation due to soft quality, soft paper shell plate corner protection and fiberboard edge protection are used at the upper part, and # is typed with iron waist to prevent folding and loose packaging

(2) ordinary printed aluminum plate, long-distance transportation: smooth wooden supporting plate is used at the bottom to prevent the aluminum plate from soft deformation. Triangular iron is used to protect the edge at the upper part, and # is marked with iron waist to prevent folding and loose packaging. Then, it is covered with wooden box, marked up and down, and then packed with # is marked with iron waist

(3) the packaging requirements for plates with adhesive and lubricant on the back are the same as those for long-distance transportation of printed aluminum plates: this kind of plate is relatively slippery, and the finished printed aluminum plates will fall to the ground with a slight push without packaging. A smooth wooden support plate is used at the bottom to prevent the aluminum plate from deforming due to soft quality. The upper part is protected by triangle iron, and the word # is marked with an iron waist to prevent folding and loose packaging. Then, it is covered with a wooden box, marked up and down, and then packed with an iron waist

glazing and packaging are the post press processing processes of aluminum plate printing. Although they are the last processes, their importance cannot be ignored. Many exquisitely printed aluminum plates are disqualified due to unqualified glazing or packaging, which not only delays the completion date, but also brings many economic losses to enterprises