definition
Hot stamping process: It is a process in which metal foil is transferred to the surface of printed matter or other articles by hot pressing to increase the decorative effect. Cold bronzing process: It is a process that transfers metal foil to the surface of printed matter or other articles with no effect of heating, only by pressure and the force of adhesion and peeling.
purpose
The printing surface can have multiple colors of metallic texture at the same time. In addition, different hot stamping effects can be combined. In addition to the surface decoration function, hot stamping also plays an important role in preventing forgery.
Advantages and disadvantages of bronzing process
advantage:
1) Hot stamping products on the whole surface without ink residue;
2) No bad smell such as ink, no pollution to the air;
3) One-time stamping of the color pattern is completed to reduce the loss;
4) Simple procedures, smooth production management and process movement, large product quality insurance coefficient;
5) Wide processing range, suitable for paper, wood, plastic, leather, etc.
Disadvantages:
1) It is not suitable for substrates with bumps or matte surfaces on the hot stamping surface;
2) Metal, glass, ceramic, nylon and other products are generally not suitable for hot stamping, unless they are first painted or screen printed;
3) The matching of the pattern color with the background color of the workpiece: When stamping, the hiding power of the color of anodized aluminum (gold, silver, copper, inner red, inner blue) is very strong, even if the background color of the workpiece is black, it can be completely covered; When using lighter-colored transfer papers such as white and yellow on a black background for hot stamping, the covering effect is not as good as pad printing or screen printing.
classification
Flat ordinary stamping
1. The production process of ordinary flat hot stamping plate (commonly known as “up plate”)
The quality of the hot stamping plate is an important factor affecting the quality of the hot stamping. The production of ordinary flat hot stamping plates mainly adopts photo-etching and electronic engraving platemaking processes. The former is simple in production process and low in cost, but the precision of the produced hot stamping plate is also relatively low, limited to hot stamping text, thick lines and quality requirements Low pattern; the hot stamping plate produced by the latter has high accuracy, which can richly and delicately express the operation of image layer equipment, and can reproduce fine lines and uneven thickness graphics well. The cost is relatively high and the scope of application It is widely used in cigarette packs, wine packs, medicine packs, cosmetics packaging, etc., which require high stamping effects.
2.Material selection of ordinary flat hot stamping plate
The common plate material for common flat hot stamping plate is copper plate or zinc plate. The copper plate has a fine texture, a smooth surface, good thermal conductivity, wear resistance and pressure resistance, and is not easily deformed. It is favored by most platemaking factories. For information on print manufacturers with a small quantity and low quality requirements, the plate of the hot stamping plate can be a zinc plate.
3. Material selection for ordinary flat hot stamping base plate (commonly known as “next page”)
At present, most ordinary flat hot stamping plate making plants only produce hot stamping plates, and due to the different hot stamping media, the plate making factories cannot provide suitable matching master plates. Therefore, most carton packaging companies are facing the choice of ordinary flat materials. The problem of hot stamping the master. Comprehensive packaging factors such as hot stamping media, print resistance, adaptability, and ease of operation. It is summarized as follows: For coated art paper printing, ordinary PS can use waste PS plate, steel doctor blade, and solid kraft paper with a thickness of about 0.5mm as the master plate; for gold cardboard, silver cardboard, and laser cardboard For glass cardboard, you can use 0.8 ~ 1.5mm thick insulation board and steel scraper blade as the master plate; no matter what kind of master plate is used, it is indispensable to clamp the pressure paper underneath. .
4.Technical requirements for ordinary flat stamping
1) Anodized aluminum
Ordinary anodized aluminum is composed of 4 to 5 different materials, including a base film layer, a peeling layer, a coloring layer, an aluminum plating layer, and an adhesive layer. The speed and quality of hot stamping are mainly affected by the peeling layer and the adhesive layer. If these two coatings are not sensitive enough to heat, the speed of hot stamping will be reduced accordingly.
2) Temperature, pressure, speed
These are the three major elements of the hot stamping process. Only by controlling the relationship between the three can the hot stamping quality be controlled. The temperature of ordinary flat stamping is generally 70 ～ 110 ℃, the temperature is too low, the adhesive layer and peeling layer of anodized aluminum cannot be fully melted, and the anodized aluminum cannot be completely transferred during hot stamping, resulting in hot stamping; if the temperature is too high, the paper The deformation is serious, and it is easy to cause problems such as inaccurate overprinting, misprints, handwriting, and discoloration of anodized aluminum. The stamping pressure should be adjusted to the appropriate according to the bearing capacity of the stamping medium and the upper and lower plates. The stamping speed: manual stamping is generally controlled at 600-700 sheets / hour; automatic stamping machines are generally controlled at 3500 ～ 5000 sheets / hour.
Three-dimensional hot
It can finish hot stamping and embossing at the same time, reduce the processing steps and the amount of waste products caused by inaccurate overprinting, improve production efficiency and product quality. It is mainly used in various high-end cigarette packs, wine packs, medicine packs, cosmetics packaging, etc. Hot stamping of carton packages.
1. Definition (also known as bump hot stamping, three-dimensional hot stamping, and embossing). Three-dimensional hot stamping means that the graphics processed by hot stamping have obvious three-dimensional layers, which stand out on the printed surface. Three-dimensional bronzing technology is a composite technology combining hot stamping technology and bump stamping technology. It can also be regarded as a combination of “hot stamping + bump stamping” technology. It uses corrosion or engraving technology to make the hot stamping and bump stamping graphics into a top and bottom. With the combination of negative and positive mold intaglio printing, the hot stamping and embossing technology can be realized in one process.
2. Principle Three-dimensional hot stamping: hot stamping and embossing are completed at one time: using a hot stamping plate and a bottom mold, under a certain pressure and temperature, plastic deformation of the printed substrate, and at the same time, anodized aluminum foil is printed on the printed matter or other substrates. Plastic deformation on the surface, so as to artistically process the surface of the printed matter. Electric engraving three-dimensional hot stamping plate has high precision, and the hot stamping effect is very exquisite. The electro-engraved brass plate is generally used in post-press processing. It is controlled by computer software to 3D engraving the pre-scanned image. The hot stamping plate produced in this way can be used for pre-printed relief for three-dimensional hot stamping. The key of this process is plate making. The graphic part of the hot stamping plate should be rounded lines, which is different from the right angle lines of ordinary flat hot stamping plates. Therefore, the three-dimensional hot stamping plate requires secondary processing after corrosion, which is technically difficult. .
1) Production of bump hot stamping plate (commonly known as “previous version, negative version”)
The production principle of the concave-convex hot stamping plate is more complicated than that of the ordinary flat hot-plate, and because it also needs to achieve the concave-convex effect, the concave-convex hot-plate has a depth change, and the relief depth of the graphics is deeper than the ordinary flat hot-plate. Some, higher accuracy. At present, domestic plate-making factories use computer-engraved brass plate-making process for typesetting, and the bump-stamping plates produced are rich in layers, fine, and highly resistant to printing.
2) Production of bump hot stamping base plate (commonly known as “lower version, positive version”)
The base plate used for embossed hot stamping must be a male mold relief plate corresponding to the embossed hot stamping plate. At present, the base plate material commonly used by platemakers is glass fiber, which can be made in advance according to the model of the embossed hot stamping plate, and produced with the processed copper plate Positioning hole layout design for easy replacement and positioning.
The master plate must correspond exactly to the embossed hot stamping plate, but in the process of embossed hot stamping, as the temperature gradually increases, the embossed hot stamping plate will swell, but the temperature of the base plate remains unchanged, which will cause embossed hot stamping. The plate is not matched with the base plate, which causes the base plate to be crushed or the hot stamping pattern to be incomplete. Therefore, the expansion rate of the concave-convex hot stamping plate should be fully considered when making the master plate to ensure that a more accurate master plate is produced.
3) Process requirements for bump hot stamping ① Anodized aluminum. Anodized aluminum should be used instead of ordinary anodized aluminum. ②Temperature, pressure and speed. Concave-convex hot stamping needs to complete the hot stamping and embossing publishing at one time. Therefore, the hot stamping temperature is very high. Usually it can be completed at 110 ～ 140 ℃. However, the high temperature will cause problems such as pasting and discoloration of anodized aluminum. Will make the gravure hot stamping plate swell too much, can not be accurately matched with the base plate, the phenomenon of bad hot stamping. It can be said that the hot stamping temperature is the primary factor that determines the success or failure of bump hot stamping.
Holographic positioning hot stamping
Holographic positioning hot stamping is a special hot stamping process. It uses the anti-counterfeiting pattern on anodized aluminum, which can not only greatly improve the anti-counterfeiting performance of the product, but also improve the grade of the product. It is mainly used for various carton packaging that requires anti-counterfeiting functions. 1. Definition: Hot stamping anodized aluminum is a holographic image, and the image needs to be accurately positioned on the stamping process. There are two types of holographic stamping: ordinary stamping and positioning stamping. Holographic positioning hotspot is a combination of laser holographic image anti-counterfeiting technology with good anti-counterfeiting effect and hot stamping decoration technology, which makes the product increase anti-counterfeiting performance while improving decoration and decoration. Laser holograms are made based on the principle of laser interference using spatial frequency coding. Laser holograms have amazing colors, obvious layers, vivid images, changing optical transformation effects, and high information and technology content.
2. Principle: The hot-melt adhesive layer and the separation layer on the holographic hot stamping material are heated and melted by the hot stamping die on the hot stamping equipment. Under a certain pressure, the information layer holographic grating of the hot stamping material is melted. The stripe is separated from the PET substrate, so that the aluminum foil information layer is adhered to the ironing surface and integrated into a perfect combination.
1.Production of holographic positioning hot stamping plateThe production process of holographic positioning hot stamping plate is basically the same as that of ordinary flat hot stamping plate and bump hot stamping plate
2.Hot stamping process requirements Holographic positioning hot stamping must use a special laser anodized aluminum and advanced register detection system, which determines that the holographic positioning hot stamping has higher requirements on the properties of hot stamping materials and hot stamping machines than other hot stamping methods. Stricter and higher. ① Adjustment of registration detection sensor: The adjustment of detection sensor (sensor) is the most important step in holographic positioning and hot stamping. The more common adjustment method is: In the clear state, the indicator light is on when the cursor is encountered, and it is off when there is no cursor. However, in actual production, when the above-mentioned adjustment method is used, it often encounters the problem of continuous alarm due to the detection of the electric eye not finding the cursor, leading to shutdown and causing a lot of waste. The correct adjustment method is: Be sure to observe and detect the reaction state of the electric eye when the machine is running, and then make corresponding adjustments, so as to ensure that the detection of the electric eye is sensitive and accurate. ② The treatment of laser anodized aluminum plate: Scanning during holographic positioning and hot stamping. Since most of the holographic anti-counterfeit patterns on the anodized aluminum are arranged independently and intermittently, a seam will appear at a distance from the anodized aluminum during operation. (Seam stitching). At this time, if it is difficult to control the normal steps of holographic positioning hot stamping anodized aluminum, it will be impossible to avoid the seam stitching, which will cause hot stamping waste. Therefore, controlling the holographic positioning and hot stamping procedure of anodized aluminum is also an important factor for the success of holographic positioning and hot stamping.
3. Other matters needing attention: ①During the hot stamping process, sometimes the printed products are not hot stamped due to UV varnishing, which is caused by the incompatibility of anodized aluminum and UV varnish. At this time, the method of UV glazing should be adopted after hot stamping. ② If the print to be ironed still needs to be transferred by laser embossing, then the method of hot stamping and then laser embossing cannot be used. It must be laser embossed and then transferred. There are two main reasons: First, the surface of printed products after hot stamping is often uneven, and the paper is deformed, which will seriously affect the effect of laser imprint transfer. Second, scattered aluminum scraps, paper scraps, dust, and the pre-processing machine The oil stain on the belt not only affects the laser imprint transfer effect, but also may damage the glazing plate used for laser imprint transfer.
4. Holographic positioning hot stamping technology, also known as holographic marking hot stamping technology or special edition hologram positioning hot stamping technology, is a new type of laser anti-counterfeiting technology that has been widely used at home and abroad. Mainly used for security of various tickets, credit cards, passports, banknotes, trademarks, tobacco and alcohol packaging and important publications. According to the characteristics of hologram hot stamping logo, holographic hot stamping is divided into continuous pattern hot stamping and independent trademark hot stamping.
① Continuous holographic logo stamping; ② Independent pattern holographic logo stamping;
Material selection for bronzing version
High-quality stamping version is the first factor to ensure the quality of stamping. Bronzing plate materials are commonly used copper plate materials, copper plate materials are delicate, surface finish, heat transfer effect is good, the use of high-quality copper plate can improve the gloss and contour clarity of bronzing graphics. Plates currently used for bronzing include stainless steel, brass, copper, magnesium and zinc. As to which type of plate to choose, it should be comprehensively considered according to the order quantity and production efficiency of the product.
1. Selection of plate materials ① There are generally two types of plate materials for hot stamping, namely copper plate and zinc plate. Among them, copper plate is divided into brass plate and red copper plate. ② The brass plate is suitable for hot stamping large quantities of hard objects, which has a certain degree of heat resistance and heat transfer, and is durable and difficult to deform. If hardcover bookcases with cardboard are stamped, a brass plate can stamp more than 200,000. ③ The red copper plate is a dark reddish plate. The red copper plate has good heat transfer, heat resistance, firmness and durability, and is not easy to deform. Red copper is a neutral metal and has a certain elasticity. The handwriting and patterns produced by this hot stamping plate are soft and plump, which is different from other plates. ④ Zinc plate is another kind of metal plate material, its texture is softer than copper plate, its durability and heat resistance are worse than copper plate. The zinc plate is suitable for hot stamping general paper and paperboard products in small batches (such as thousands of products). If the object is hard or the number of hot stamping is large (such as more than 10,000), the print on the hot stamping plate It will gradually blur and damage, and the hot stamp marks of the hot items will not be clear, and even cause defective products and waste products. ⑤ In terms of price, the zinc plate is slightly cheaper than the copper plate, but comprehensively considering the durability, the copper plate is more affordable. The printing resistance of a copper plate is dozens of times that of a zinc plate. Therefore, when selecting hot stamping plates, various aspects must be considered to ensure both quality and cost savings.
2. Selection of the thickness of the stamping plate The thickness of the stamping plate should be determined according to the texture of the object and the size of the stamping area. Now the thickness of the hot stamping plate is relatively thin, generally about 1.5mm, which can be used for hot stamping ordinary plain paper. If the following items are to be stamped, the thickness of the stamping plate must be increased.
1) The surface of the object to be ironed is velvet, satin, linen textiles. The velvet in textiles, especially thick velvet, has very high fluff on its surface (about 3mm); while satin and linen textiles are thick by themselves and have great elasticity. If it fails to meet the requirements, it will cause faults such as hotplate paste and dirty plates, causing unnecessary losses. When stamping such materials, the thickness of the stamping plate should be thickened to about 3.5mm before it can be used.
2) The surface of the object being hot is uneven or has a raised pattern. Some objects to be stamped, such as lacquer-coated, PVC coated paper, special pattern paper, etc. Some of these materials have a plain pattern on the surface, and some have different patterns with different shades. Pressure on the object being scalded. When stamping such articles, the thickness of the stamping plate is generally increased to 2.5mm.
3) Hot stamping genuine leather, recycled leather, synthetic leather items. This kind of scald is generally expensive and flexible. Especially the genuine leather (generally sheepskin), the skin is thick, a piece of sheepskin will cost one hundred or two hundred yuan, if the hot stamping plate is too thin, it will cause great losses. When stamping such articles, the thickness of the hot stamping plate should also be about 2.5mm.
4) Graphic with large stamping area. Some objects need to be hot stamped over a large area. The hot stamping pressure required is too large, and the too thin hot stamping plate cannot withstand the large pressure. Even if it can barely withstand the large pressure, it is easy to appear dirty Phenomenon, can not achieve the ideal hot stamping effect. For large-area hot stamping, a hot stamping plate with a thickness of about 2.5mm should also be selected. In addition to the above, the thickness of commonly used hot stamping plates (except gravure) can be selected about 2mm.
Mastery of bronzing pressure, temperature and time
In addition to proper selection and handling of hot stamping plates and reasonable selection of hot stamping materials in hot stamping processing, mastering the pressure, temperature and time during hot stamping is also critical. Mastering these three points correctly and flexibly in actual operation is an important condition for doing a good job in hot stamping.
1.Mastering the stamping pressure
①The size of the stamping pressure should be determined according to the nature, thickness, type of stamping, and size of the area being stamped. The pressure of the hot stamping should be limited to the clear imprints, sharp edges and corners, bright, and not embossed after the hot stamping; the pressure of the hot stamping should be firm, not to fall off, not embossed, clear, and clearly marked. . If more than two types of images with large differences in area size are to be stamped on the same plate at the same time, it is necessary to grasp the pressure per unit area and the force of the object being hot. The larger the stamping area. The greater the pressure, the less the opposite.
②The hot stamping pressure of the automatic hot stamping machine can be adjusted automatically according to the required pressure of the object to be ironed. It is more convenient to adjust, but it will be restricted by factors such as uneven thickness of the object. Once the thickness of the object to be scalded is not uniform, the phenomenon of paste printing or flower printing will occur.
③ Hot stamping with a manual hot stamping machine mainly needs to grasp the pressure of the hot stamping plate after it contacts the object being pressed. The pressure should be increased during the indentation, which is very necessary in operation. Although manual hot stamping is cumbersome, the pressure can be adjusted freely according to needs, and it is not affected by factors such as the thickness of the object to be stamped. It can also be used for hot stamping difficult items.
2. Mastering the hot stamping temperature and hot stamping time The hot stamping temperature and hot stamping time should be determined according to the material being hot stamped and the hot stamping form. In actual hot stamping, if the hot stamping temperature is too high and the hot stamping time is too long, there will be phenomena such as stenciling, indistinct graphics and matte, etc .; on the contrary, there will be no hot stamping, shedding after hot stamping, pattern printing, etc. phenomenon. Both the hot stamping time and the hot stamping temperature can be fine-tuned during work. For example, when the hot stamping plate temperature is slightly higher, the hot stamping time can be shortened slightly; when the hot stamping temperature is slightly lower, the hot stamping time can be adjusted appropriately. Longer. The adjustment range of the two should not be too large, and should be controlled within a certain range. As long as the adjustment is appropriate, a good stamping effect can also be obtained. If hot stamping is required at the same time, the hot stamping temperature can be appropriately reduced by 10-20 ° C, and the hot stamping time can be increased by 1 second, which can increase the fastness of the stamp.
Bronzing paper
1 Overview
2. For bronzing, the most important auxiliary material is the bronzing paper font, which is what we call anodized aluminum. The types of anodized aluminum are roughly divided into ordinary and laser, and laser is divided into plain and flower plate. The performance of various types of anodized aluminum is not the same, and some of the same model but different batches, its comprehensive performance will also change.
Laser anodized aluminum: The film material is printed on PET tickets, and the film thickness is 14-18μ. Laser anodized aluminum has beautiful, bright, rich colors and other characteristics, and the applicable temperature is between 110 ℃ -150 ℃. There is also the online publication of laser holographic positioning hot-dip anodized aluminum, which is mainly used for cigarette labels, wine boxes, cosmetics packaging, etc. It is the most popular anti-counterfeiting method in the hot stamping industry, and the applicable temperature is between 110 ℃ -150 ℃.
Ordinary anodized aluminum. The material is PEF film with a thickness of 12-14μ. It has gold, red, copper, blue, black and other colors. The applicable temperature is between 90 ℃ -120 ℃.
2. The structure of anodized aluminum usually uses PET film as the tape base; the bottom layer is a release agent and color paint, the middle is a vacuum sprayed aluminum powder layer, and the surface is an adhesive (thermosol). As shown in the figure: 3. When selecting, choose according to the size of the hot stamping pattern. Pay attention to the following points when selecting:
1) Adhesive properties (ie, bronzing adhesion). 2) Separability. 3) Ability to withstand hot stamping patterns. 4) Adaptability to ink. 4. An easy method to identify the tightness of anodized aluminum primer: stick with transparent adhesive tape, or rub it by hand. If the color layer is easy to fall off, it means that the adhesive layer is loose and easy to be stamped, which is suitable for ironing large areas. ,line. But not absolutely gravure, the choice is more reliable after trial. The hot stamping suitability of anodized aluminum includes surface finish, brightness, sharpness, hot stamping suitability for graphics and small text, surface flying gold and burrs, and other inks. It should be based on different printing materials, packaging product levels, and electrification. Aluminum price and hot stamping suitability weigh the options. 5. High-quality anodized aluminum should meet the following points:
1) The color layer is painted uniformly, and there is no visible color flower after hot. 2) Good luster and no black spots.
3) Viscose coating is uniform, smooth and without obvious streaks. The second important material for bronzing is the bronzing version, which is generally made of aluminum, zinc, magnesium, copper, and brass. The surface of the bronzing plate pattern and the non-embossed surface have a depth of 1-1.5mm, and the inclination angle is between 15 degrees and 30 degrees. 6. The layout must be smooth and clean, and tiny speckles and scratches will be reflected on the printed products after hot stamping.
Forming process of the hot stamping process: When hot stamping, the whole printing exhibition is heated, the adhesive changes to a liquid state, and the anodized aluminum is stamped on the printed matter with an electric plate, and then the stamping is separated from the aluminum layer and the color layer to complete the hot stamping, as shown in the figure:
7.Bronzing paper performance
①The hot stamping performance of anodized aluminum depends on the isolation layer and the adhesive layer.
② The looser the isolation layer, the easier it is to attach to the printed product.
③ The thicker the adhesive layer, the easier it will be to adhere to the printed product.
④The hue of anodized aluminum depends on the dyed layer
8.Bronzing paper appearance quality
① There are no obvious scratches or defects on the anodized aluminum front side (color side).
② The hue of the same type of anodized aluminum is basically the same without any difference.
③ The adhesive layer is coated uniformly without obvious streaks. 9, hot stamping paper requirements
① Strong adhesion: The adhesive layer on the surface of the anodized aluminum foil can be firmly adhered to a variety of hot stamped objects with different characteristics, and should not fall off or stick together under certain temperature conditions; for special hot stamped objects, electrochemical Special adhesive materials should be used for the aluminum foil adhesive layer to meet special needs; the adhesion firmness is also related to the process conditions such as stamping time, stamping temperature, and stamping pressure. Adjusting the stamping process can also improve the firmness of the electrochemical foil stamping. degree.
② Stable performance of the foil film: The chemical properties of the dyed layer of the anodized aluminum foil should be stable. It does not change color when hot stamped, coated, and glazed. The surface film layer is not damaged. After the hot stamping into the text, it should have a long-term resistance. Heat, light, humidity and corrosion resistance. ③ The separation layer is easy to separate: The separation layer should be adhered to the substrate and easy to separate from it; the aluminum foil product must not be separated from the substrate during production, transportation, and storage; when it encounters a certain temperature and pressure, it should be separated from the substrate immediately. The heated and pressed parts must be completely separated, so that the aluminum layer and the dyed layer can be smoothly transferred to the surface of the hot stamping material to form a clear picture. The parts that are not heat-pressed are still adhered to the substrate and cannot be transferred. The transferred and non-transferred parts must be clearly separated and neat. ④Clear and smooth graphics: within the operating temperature range allowed by the hot stamping, the electrochemical aluminum foil does not change color, and the size of the “four-letter” stamps is clear and smooth, and there are no or fewer pieces between the lines and strokes. The dyed layer of the anodized aluminum foil should be coated uniformly. The aluminized layer has no trachoma, no creases, and no obvious streaks. The clear imprint is an important property of the anodized aluminum foil. The handwritten stamp should be free of burrs, which is related to the adhesion of the separation layer and the adhesive layer, and whether the coating is uniform.