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Understanding: the offset printing process on the laser bronzing pattern

in the increasingly fierce market competition, everyone is working hard to create their own brand and make their own products stand out. The laser anodized products, which are hot stamped with exquisite bronzing process, are rich in color and colorful. Combined with rich offset printing technology, the products not only have a strong visual impact of resplendence, smoothness and three-dimensional transparency, but also greatly improve the anti-counterfeiting performance of the products, playing an unexpected anti-counterfeiting effect unconsciously. It is unique and popular on numerous commodity counters

to use offset printing process to print exquisite products on bronzing products, in addition to reasonable process design and standardized operation, we should also pay attention to the following aspects

1 quality of anodized aluminum

because printing is carried out on anodized aluminum, as an offset substrate, the quality of anodized aluminum plays a vital role in printing. The phenomenon of flying gold, reverse drawing and bubbles in anodized stamping will seriously affect the quality of offset printing. The quality of offset printing is mainly affected by the adhesive layer and stripping layer of electrochemical aluminum

1) effect of the stripping layer (protective layer) of anodized aluminum on offset printing quality

the stripping layer of anodized aluminum, also known as protective layer, adhesive layer or thermal layer. It is composed of natural or complete paraffin. Its thickness is very small, only 0.01 M, but it plays a great role. Especially for printing on this layer, it needs to have the following characteristics at the same time:

① good adhesion

at room temperature, paraffin makes pet or PVC film carrier adhere to the film base, so that it is not easy to fall off, so as to avoid serious phenomena such as gold flying and electrochemical aluminum falling off during bronzing

when the gold flying and powder dropping are serious during the bronzing process, in the offset printing process, the dropped gold powder will be adsorbed and accumulated on the surface of the rubber blanket of the offset press, affecting the transfer of offset printing ink and the correct transfer of points, thus reducing the clarity of the printed pattern. In serious cases, the rubber blanket will have to be scrubbed every hundreds of copies. Cleaning the rubber blanket so frequently not only seriously affects the production efficiency, but also directly affects the color stability of the product. However, the sensor adopted by Shanghai xinrenda Instrument Co., Ltd. is American, with high precision, which can be used for more than 150000 times

② good ink adsorption

during bronzing, the paraffin quickly interlocks with the three groups of normally open connection points of the sheet contactor 3C to operate the swing taking, impact and swing releasing. After the base layer is separated, it will experience a series of physical changes (solidification liquefaction solidification), and finally solidify on the surface of the bronzing pattern to form a protective layer. During printing, the ink is in direct contact with this layer. If the ink absorption of cured paraffin is too poor, it is learned from the press conference of Western China (Chongqing) plastic ecological industrial park that it is easy to cause ink falling off and color change. Therefore, we generally require electrochemical aluminum manufacturers to put forward requirements for this layer, requiring that the surface tension dyne value must be above 38 to meet the printing requirements

2) effect of the adhesive layer of electrochemical aluminum on offset printing quality

during bronzing, the adhesive layer of electrochemical aluminum should be well bonded with the paper and maintain a certain strength. Otherwise, the gold foil will be pulled out by the blanket in the offset printing process, resulting in quality problems such as plate pasting, ink transfer failure, color change, etc. Therefore, the most important thing for bronzing is to make the combination of adhesive and hot stamping substrate better, that is, the adhesion between electrochemical aluminum and paper is greater than that of offset printing ink. Therefore, the selection of electrochemical aluminum materials suitable for offset printing is the most effective way to solve reverse drawing

2 bronzing pressure

bronzing pressure is an important condition for transferring gold foil to paper. As the product needs padding treatment during bronzing, the surface of the gilding pattern after padding treatment inevitably has subtle concave convex shape and uneven thickness. If the printing pressure is uneven, the printing ink on the layout will inevitably appear uneven, point deformation and deficiency, and in serious cases, printing failure will occur

generally speaking, the bronzing pressure should not be too high, but it should not be too low. If the bronzing pressure is too high, the offset printing method is to locally pad the back of the blanket, the impression cylinder and the lining. However, this method is not only time-consuming, but also damage the offset printing equipment. The bronzing pressure is too small, which will cause insufficient adhesion between the anodized and the paper, and cause the anodized to pull back and drop the powder

due to the relatively complex and difficult operation of the offset printing pad, it is better to solve the problem from bronzing:

improve the surface flatness of the bronzing plate

minimize the local bronzing pad pressing

avoid steep slopes during bronzing pad pressing

make the bronzing pressure reasonably match the offset printing pressure

special attention should be paid to the uneven pressure on the same plate during local bronzing pad pressing, Offset printing may cause false printing, and pressure treatment must be carried out at this time. During pressure treatment, there will be several hues on a page. Therefore, when stamping, try not to adopt the supplementary pressing method of local padding on a pattern

in order to check whether the electrochemical aluminum has reverse pulling and powder dropping, the general practice is to use ordinary transparent adhesive tape for inspection. If it is easily pulled out, it is easy to have reverse pulling in offset printing

3 registration

because it is printed on specific bronzing patterns, offset registration is aimed at each bronzing pattern. Any fluctuation in bronzing registration will directly affect offset registration. If the next process is to be processed on the offset pattern, the offset registration will affect the next process. Therefore, from product process design to production sample signing, we must make a detailed regulation on the registration of each process in advance. For example, sorting the regular lines in the production process, marking the products that have been moved regularly, and random speed change is not allowed in the production process

bronzing may cause registration fluctuation due to the following reasons

paper stretch deformation

change of bronzing pressure

displacement of bronzing plate

the bronzing machine speed changes

registration fluctuation of the bronzing machine itself

poor paper feeding

generally speaking, to stabilize the printing pressure of offset printing and adjust the paper feeding of offset printing, the following methods can be used to control the registration

consider the printing process to meet the slight registration fluctuation

bronzing check whether the bronzing position is accurate with the offset product according to the offset product version

stabilize the registration of bronzing. After offset printing, the bronzing products are used to remake plates according to the registration of bronzing. This is a commonly used method at present. If the registration of bronzing is unstable and fluctuates greatly, it will increase a lot of costs

use the film to control the registration of bronzing, and use the edge contour of the bronzing pattern to draw a film with a side line of 50. During bronzing, use this film to check the registration fluctuation of the bronzing machine

in the actual production process, we often encounter problems such as reverse pulling and powder dropping. The general remedies are:

re hot pressing the product

reduce the viscosity of ink

reduce printing pressure and machine speed

medium (hard) rubber blanket

use special blanket

in use (hard) lining

dig grooves in the blanket

in recent years, our company has successfully combined bronzing and offset printing with new materials with a complete tensile strength higher than that of HDPE pipes, which not only creates a brand for customers, but also improves our own market competitiveness (at present, many products have used this technology), but also drives the development of relevant processes and technologies

printing on bronzing patterns is a relatively complex new technology. It mainly uses complex technology to show the uniqueness of products and play a good anti-counterfeiting role. However, if the process design is improper, there will be disconnection between processes and poor cooperation, which will lead to registration fluctuation, printing reverse pull and uneven pressure, which will seriously affect the product quality and thus affect the market image of the product

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