Postpress Technology 1000 Questions (190-199)

190. What is the mechanism of electro-aluminum hot stamping?

The essence of electro-aluminum hot stamping is the use of hot-pressing to transfer the aluminum layer to the surface of the substrate. The specific mechanism of this process is: during the hot pressing, the hot melting silicone peeling layer and the adhesive are melted by heat, the adhesive force of the hot melt silicone resin is melted, and the aluminum layer is peeled from the base film. The thermal adhesive bonds the aluminum layer to the print under the effect of heat and pressure. At the moment of separation of the imprint lithography, the hot melt state of the adhesive is converted into cooling and solidification, so the anodized aluminum can be firmly transferred to the surface of the object to be heated.

191. What are the steps of hot stamping anodized aluminum?

1 Determine the anodized aluminum and stamping equipment. 2 bronzing plate preparation. 3 installed version. 4 Electro-aluminum installation. 5 Hot stamping.

1 92. How to determine the aluminum and stamping equipment?

Different hot stamping substrates have different requirements for anodized aluminum and hot stamping equipment. Because the aluminum foil has certain adaptability to the hot stamping substrate, such as hot stamping on white cardboard, ink layer, UV ink and composite film, the required aluminum material is slightly different. For example, due to the difference in the manufacturing processes of laser aluminum and ordinary aluminum, it is difficult to strip the laser aluminum in the hot stamping. The phenomenon is reflected in the fact that the hot stamping of the aluminum foil is not true, the peeling is not complete, and the hot stamping does not occur. Spots. Appropriate anodized aluminum should be selected based on the texture of the printed substrate (substrate). Selecting the right equipment for different hot stamping substrates is also important. For example, in the case of hot stamping on coated paper, since it is required that the time of thermal contact between the electrodeposited aluminum and the film is not too long, but it is necessary to ensure that the electrodeposited aluminum can be normally transferred, so in the case of using the same kind of anodized aluminum for the film. Only the flattened hot stamping method can do the job. Because the round stamping method is line contact, the entire paper stamping time is longer, but the contact time evenly distributed on each line is short, so as not to damage the film layer, and the temperature is even, and the hot stamping can be better displayed. Electrochemical aluminum bright effect. When hot stamping a large area of ​​anodized aluminum (such as field, through the lines), the round flat stamping hot stamping method is also better than the flat stamping hot stamping method. Because the flattened wire contact method is more easy to eliminate the aluminum stripping and the air completely eliminated, effectively solve the hot stamping in the flat stamping stamping often appear false and paste and difficult to control the smoothness of the paper feeding and other phenomena . Although the round press hot stamping machine has great difficulty in solving the hot stamping accuracy, the hot stamping speed is fast, and it is suitable for processing large-volume long-run games.

193. What is the version of the plate used for hot stamping of anodized aluminum?

The printing plates used for hot stamping of aluminum are mostly copper relief plates, which are characterized by good heat transfer performance, pressure resistance, wear resistance and resistance to deformation. When the number of hot stamping is small, zinc relief can also be used. Copper-zinc plates require a thick plate of 1.5 mm or more. When making the plate, the corrosion is required to be slightly deeper, and the difference between the height of the graphic and the blank should be as large as possible. This can reduce the occurrence of contiguous and stencil printing during hot stamping, which is beneficial to guarantee the quality of hot stamping.

194. Photographs of the process of drying the metal relief printing plate What are the steps?

The method of photographing the relief printing plate is that the negative plate film is transferred to a copper plate or a zinc plate coated with a photoresist, and the picture is formed by etching. The drying process of metal relief is:

Plate grinding A coating photosensitive liquid A printing version A developing a baking version A revision A corrosion A full-page inspection

1 95. What is the purpose of printing metal relief for plate base grinding?

The purpose is to use physical or chemical methods to remove oxide and oil on the surface of copper and zinc plates to improve their adsorption properties. The specific method is as follows.

1 zinc plate grinding method

Solution A: An aqueous solution of nitric acid with a concentration of 8. Be'
B liquid: aqueous hydrochloric acid, concentration l1. Be'
C fluid: (antioxidant): Potassium dichromate 50g
Water 250mi
The plate base should be treated with liquid A before grinding, washed with water, treated with liquid B, washed with water, and finally placed in liquid C for several minutes.

Rub several times on the front of the zinc plate with water-sanded paper and rinse with water.

2 copper treatment liquid

Salt 270g Water 1O00ml
Acetate 100m1

1 96. What is the operating point of drying metal letterpress coating photosensitive liquid?

The photosensitive liquid was uniformly coated on a metal base plate and dried with heating to form a photosensitive layer. Photosensitive liquids are mostly composed of ammonium dichromate and gelatin, polyvinyl alcohol or shellac and other polymer film forming substances. The sensitized solution of ammonium dichromate and shellac is called cold enamel photographic solution (they do not need to be baked prior to etching). It is suitable for making zinc plate, avoiding zinc plate heating and then crystallization, resulting in rough printing plate and brittleness. Telescopic degumming, difficult to corrosion defects. But can not be used for copper plate drying, because shellac is insoluble in water, need to use ammonia as a solvent, ammonia and copper will form a complex copper ammonium salt, increase the photographic effect, so that the layout blurred. The metal plate coated with the photosensitive liquid should be heated and dried at a heating temperature of about 70°C.

197. What are the key points of exposure (stenciling) for drying metal relief?

After the positive imposition of the film, the film is overlaid on the metal sensitized plate, and the stencil is placed in the stencil. The glass of the frame is lowered, and the vacuum pump is turned on to make the sensitized plate, the negative plate and the plate glass fully. Attached, you can turn on the light exposure. The exposure time depends on the type of light source and the distance between the lamps. The distance between the lamps should not be less than 0.5m. This can prevent the glass of the drying rack from being unevenly heated and smashing or affecting the quality due to uneven illumination.

A blue-violet light source with a wavelength range of about 360 nm is used for exposure, and the transparent portion of the negative film is hardened by the corresponding photosensitive film and loses its original water-solubility. The light-sensitive film still remains water-soluble.

1 98. What is the development operation of the metal relief printing?

The exposed metal relief plate is rinsed with water to remove the unexposed photosensitive film and reveal a graphic hardened film. The developed plate is dyed in a 3% methyl violet solution (a malachite green, alcohol solution is used for shellac) to make the picture clearly visible, and then the image quality is checked. If there is fog, cotton wool or foam can be used. Scrub with water. In order to make the photosensitive film astringent and dehydrated, it is necessary to place the plate in a 4 to 5° B color chromic anhydride hardener film, and the clear color film is black and light.

1 99. What is the purpose of baking the metal letterpress?

The roasting plate is used to dispel the moisture of the photographic emulsion film, making it porcelainized and having a high resistance to acid and corrosion. The plate is placed in an oven of 180 to 200 oc and baked at a constant temperature for 10 to 20 minutes. At this time, the plate is uniformly deep. Maroon, and shiny.

Source: Author of "Guangdong Printing" / Jin Yinhe