Discussion on cold ironing technology (on)
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Summary
In the fierce market competition, in order to increase the added value of products, more effective packaging anti-counterfeiting, more and more packaging products use hot stamping technology, and this research is aimed at the development and current status of cold-hot technology and its cold stamping type and The principle of production is discussed, and the advantages and disadvantages of cold-hot technology and blanching technology are analyzed. Cold ironing technology is generally divided into dry cold and wet cold. The cold-hot technology uses a printing adhesive to transfer metal foil, and the cold stamping technology has low cost, saves energy and high production efficiency, and is a new technology that meets the processing market demand in the future.
First, Introduction
In recent years, due to the increasing importance of the field of printing and packaging, unique and beautiful design and processing techniques have gradually become part of the packaging of goods. The hot stamping technology and the packaging market can be described as closely related. The packaging design of high-quality hot stamping foil makes the product bright and beautiful, and improves the quality and value of the packaging. The early hot foil technology is mainly based on hot foil. Due to the rapid development of cold stamping technology in recent years, it can be applied to flexographic printing, lithographic printing, etc. The cold-hot technology is different from the hot-blasting technology, which requires complicated equipment and fast production speed, which is in line with the future high-speed development trend of the packaging industry. In the aspect of commodity anti-counterfeiting, consumers are given direct visual inspection to identify the authenticity before purchase, to prevent the packaging from being used by counterfeiters to improve anti-counterfeiting and commercial benefits. According to packaging and printing and paper processing machinery, one third of the annual turnover of the global printing market is created by the packaging and printing industry, with an annual turnover of up to 250 billion US dollars, and is still growing. The annual turnover of global book printing is only 10 billion US dollars. In 2004, North American packaging printing and processing value reached US$68 billion and is expected to grow to US$83 billion by 2009 (China Packaging Machinery Network, 2005).
In the fierce market competition, in order to increase the added value of products, more effective packaging anti-counterfeiting, more and more packaging products using hot stamping technology. The cold-hot technology does not need to use the heated metal plate, but uses the printing adhesive to transfer the metal foil, and the cold stamping technology has low cost, saves energy and high production efficiency, and is a new technology that meets the processing market demand in the future ( Cai Youzheng, 2004).
Second, the development and current status of cold ironing technology
Cold bronzing technology is the result of new technology in printing and processing in Europe and the United States in recent years. Unlike traditional hot stamping technology, cold stamping technology uses a new concept to transfer eutectic foil by cold pressing technology, which not only solves many printing bronzing. The transfer problem that the industry used to solve in the past, and the most important thing is to save energy and avoid environmental pollution during the process of making metal plates (Guan Shujuan, 2004). When the cold stamping technology is used to print the lower-drying plastic material on a narrow-width rotary press, it can be processed by attaching the device to the original equipment (Image Printing Products International, IPPI, 2001). DURPA2004 Germany KURZ uses cold foil to stamp the beverage bottle label on Nilpeter's narrow-format printing press (KURZ, 2004), while MANRoland's R-700 press also installs a cold-blowing system. Manroland is also equipped with a cold-ironing device. Awarded the prestigious 2006 InterTech Technology Award from the PIA/GATF (American Printing Industry Association/Printing Technology Council) (MANRoland, 2006). Domestic manufacturers, such as Lianyi Machinery, also designed the cold ironing equipment on the LLR-300 full-rotation batch type trademark printing machine.
In the production of cold foil foil, the world's major vacuum evaporation competitors include the world's largest manufacturer Kurz, the United States ITW Group and CRL, the United Kingdom APL, Japan NaKai and Oike, and South Korea Kolon, etc., the domestic vacuum evaporation industry began Since 1968, Japan's Toyo vacuum gold plating technology has provided 49% of Dongyang vacuum gold plating established in Minxiong Township, Chiayi County. Up to now, there are more than 10 companies, such as Donghe Vacuum Plating and Nongbao Enterprise, which was established earlier, Taiwan Vacuum The coating, Mingsong vacuum gold plating, and 岱 等 are established at similar times, and the domestic output value has grown steadily every year. In recent years, it has reached NT$4 billion, and the market development has gradually been exported. Among them, the company has a relatively large scale, and its sales of bronzing film accounts for about 3% of the global market. The main customers are Guangqun Laser (accounting for 45.84% of the sales volume of the company in 2005), and Guangqun 2005 Among the parent company's revenue share, the total amount of laser hot stamping and cold foil is 48% (Lin Daojun, 2006).
Third, the introduction of cold ironing technology
Coldfoil (coldfoil) is an important breakthrough in printing technology in recent years. It combines traditional printing and lamination technology, and it is easy to operate. The printing factory can use the cold printing technology to create and use the existing printing equipment. The same effect, the only reduction in production costs, but also re-create the added value of the product, thus becoming a new trend in the future •
1, the principle of cold ironing technology
The electro-chemical foil used in cold bronzing is a special electro-chemical foil, which is coated on the back side. The adhesive is directly applied to the position to be decorated when printing. When transferring, the electrochemical foil is in contact with the adhesive, in the adhesive. The role of the galvanic foil attached to the surface of the print (Figure 1) (Focus Label machinery, 2000).
The cold-hot process is as follows: firstly, the UV ink is printed, and after drying, a special UV-curing adhesive is printed on the surface of the ink surface where bronzing is required; then the UV drying device removes the moisture of the adhesive to a certain extent to form a very high-viscosity very thin layer. The adhesive is then cold-baked, and the aluminum foil is brought into contact with the adhesive and pressed into one by a group of metal rollers (see Figure Z). Since the bonding force between the adhesive and the foil film is large, when the waste is discharged, the portion where the aluminum foil contacts the adhesive remains on the surface of the printed matter, and is integrated with the printed matter, and the other portions of the foil film are discharged like the conventional hot stamping. Since the foil pattern transferred on the printed matter floats on the surface of the printed matter, the degree of firmness is poor, so protection must be given. Light or film on the surface of the print to protect the foil pattern. Finally, the printing process such as die cutting, waste cutting, cutting or rewinding is performed (Mark Andv. 2000).
Cold bronzing technology is divided into Dry Lamination and Wet Bronze (Wet Lamination), the main process is UV adhesive and special electrochemical metal foil, and the production technology of electro-chemical foil without hot melt adhesive is relatively simple. With the development of printing industry and the needs of various industries, cold stamping The application of technology in the commercial market has also gained greater demand and development.
(1) Dry Lamination
The early cold stamping technology adopts the dry cold stamping method. The dry cold stamping technology processes the image on the substrate, and uses UV lamps to dry and cure the UV glue on the coated substrate to make the image sticky. Use a pressure roller to turn the foil onto the attached image and remove the excess foil. The main process steps are as follows:
1. A cationic UV adhesive is printed on the web substrate.
2. Curing the UV adhesive.
3. The cold stamping foil is combined with the printing material by means of a pressure roller.
4. The excess hot stamping foil is peeled off from the substrate and the desired hot stamping is left only in the area where the adhesive is applied.
When dry cold stamping is used, the curing of the UV adhesive is carried out quickly, but it cannot be completely cured. It is guaranteed to have a certain viscosity after curing, so that it can be well bonded to the hot stamping foil.
(2) Wet-type cold (WetLamination)
The wet cold stamping method is that after the image is printed on the substrate and the UV adhesive is applied, the cold foil foil substrate is bonded by a pressure roller, and the UV glue on the substrate is dried by a UV lamp to make the image sticky. Remove excess foil. The main process steps are as follows:
1. A free radical UV adhesive is printed on the web substrate.
2. Apply cold stamping foil to the substrate.
3. The free radical UV adhesive is cured. Since the adhesive is sandwiched between the cold stamping foil and the printing substrate, the UV light must pass through the hot stamping foil to reach the adhesive layer.
4. The hot stamping foil is peeled off from the substrate and a hot stamp is formed on the substrate. Since the wet cold stamping process replaces the traditional cationic UV adhesive with a free radical UV adhesive; the UV adhesive has a strong initial tack and can be tacky after curing; and the metallization of the hot stamping foil The layer should have a certain light transmission to ensure that UV light can pass through and initiate the curing reaction of the UV adhesive. Wet cold stamping technology can be used on the press
Second, cold ironing technology materials and equipment
Generally, printing on UV flexographic printing presses uses cold stamping. The materials and equipment required for cold stamping technology are: standard flexographic printing, photosensitive resin and guide roller, hot stamping foil, UV adhesive, and embossing roller. , UV UV device, hot stamping foil unwinding device and winding device, stripping device, etc., as follows:
(1) Cold Foil
The bronzing foil looks like a film. In fact, it consists of a thin base film of PV or PE, a release layer, a colored layer, an evaporation layer (adhesive thickness), and a layer of five layers of material (Fig. 3). In fact, hot stamping foil is divided into many varieties to match the materials that have been burnt, such as PP film or polished paper, metallic ink, cloth, PVC glue, hot line stripe or large field and other materials and printed materials. It is necessary to select the hot foil of the same material for cooperation.
The main technologies of vacuum evaporation bronzing film include vacuum evaporation, coating, and chemical compounding, especially in the chemical compounding part, which is a key factor affecting the finished product (Ministry of Economics, Research Group, 2007). The core technology of general bronzing film production lies in precision coating and chemical formulation. The production process is as follows: Firstly, PET (polyethylene terephthalate) and OPP (extended polypropylene) original film will be used as materials. The resin and the solvent are colored and applied to the original film, and then a metal film is attached by vacuum evaporation, and a sizing coating process is added, followed by slitting or rolling foil (Fig. 4).
(2) UV Adhesive (UV Adhesive)
The printed adhesive is dried in an additional UV unit to conform to the foil on the surface where the print requires bronching (IPPI, 2001). In addition, there are two types of adhesives in the same type, one is free radical (Free "radical" adhesive, the other is a cationic adhesive, the difference between the two is that the free radical adhesive must be irradiated by ultraviolet light to produce a chemical reaction (Figure 5), while cationic adhesive The agent is viscous after initial curing and then finally cured to complete it (Figure 6). Both require different adhesives depending on the printer structure.
(3) impression cylinder (Niproller)
The bottom and the top roller are both 2 to 3 inches in diameter, the bottom roller is a hard metal roller, and the top roller is measured by the hardness of the rubber HS80-90, and the roller and the material to be printed need to be in full contact to avoid creases, The production of wrinkles and bubbles causes the print to be good. Therefore, if the angle between the foil and the material to be printed is too large, the foil film is broken and wrinkles are generated. If the foil and the material to be printed are not removed from the air, bubbles will be formed in the fit and sufficient pressure will be provided to ensure that the stamping can proceed smoothly (Figure 7).
(4) UV curing device (UV Curing station)
UV UV is a minimum of 300 watts per inch, and the UV curing system must be as close as possible to the imprinting device to cure the UV adhesive in time after printing and hot stamping (Figure 8). Moreover, the power of the UV curing system should be at least 300W. The UV lamp and the reflector must be kept clean and free of UV varnish and dust impurities, so as not to affect the curing effect of the UV adhesive.
(5) Hot stamping foil unwinding and winding device (FoilUnwindandRewind)
Its function is to adjust the winding tension when cleaning the waste, so as to avoid wrinkles or delamination of the hot stamping material. After the foil is cured and cured, the printed material will be separated immediately and it will not be in contact with other equipment in the appropriate space. volume:
(6) Srapping roller
The steel stripping roller has a diameter of about 2 inches, and the surface must be clean and smooth. The peeling angle is preferably peeled at an angle of 90 degrees. The peeling device is installed at the end of the UV curing system, except for peeling off the waste foil. It can also avoid the delamination of the hot stamping foil before UV curing, and it can also reduce the wrinkles and skew of the printing material.
In addition, in order to obtain high-quality hot stamping products and high profits, skilled operators are also required to be able to handle and solve various problems in the production process, especially those related to UV systems.