Application of the hottest shrink film in flexogra

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The application of shrink film in flexographic printing

facing the increasingly competitive label printing market, many manufacturers printing labels with flexographic printing have paid attention to shrink film labels, not only because of its development potential as a new technology, but also because of the high entry threshold of shrink film labels compared with those label printing markets with low technical requirements and low cost investment, Therefore, it can prevent new companies from joining the competition. Traditional flexographic printing plants have begun to purchase some technical equipment of shrink film, such as bonding devices and new printing equipment. It is estimated that shrink film labels will increase by 7% - 10% every year, which is significantly higher than the growth rate of 4% - 5% in the general label market. The reason for this result lies in the increasingly emphasized theme in packaging design: how to quickly catch the eyes of customers. It is this demand that opens the door to the small and medium-sized label market. Of course, with the introduction of personalized, national and healthy foods, and the new labeling regulations of FDA (food and Drug Administration of the United States), the labeling market has provided opportunities for growth and profit

according to the statistics of the Maryland business development association, the domestic use of shrink film labels in the United States in 2003 was 49million to 53million pounds (about US $300million). However, gravure printing accounts for most of the market, and only 15% is completed by flexographic printing

when to enter the label market

now, a variety of patented foods and some regional specialties need different packaging, which just provides a good opportunity for shrink film labels to meet customer requirements in combination with the characteristics of flexographic printing. With the development of flexographic printing technology, the printing accuracy has been continuously improved, and the prepress production cost is lower than that of gravure printing, which makes flexographic printing gradually play an important role in the self-adhesive label printing market

if you decide to enter the shrink film label market, it is necessary to refer to the current situation of flexo printing. At present, the most competitive narrow width flexographic press is to print films of less than 40million square meters, and those of more than 40million square meters are the world of wide width machines

for the drum with a width of 40 inches, 500000 square meters is the dividing point between the wide flexo press and the gravure press. This value depends on many factors, including the cost of the machine and the installation cost

two distinct markets

shrink film labels are divided into two distinct markets due to different processes: shrink tube packaging and wrapping packaging. But these two technologies can be completed by flexographic printing. Generally, the term "TD" refers to shrink tube packaging, which mainly depends on the transverse shrinkage of the film. The printed film is made into a tube shape and put on the container, and then the film is heated to cause the film to shrink laterally, so that it is tightly combined with the container

wrapping and packaging are guided by the direction of machine operation. When the film is heated, it shrinks according to the direction of mechanical movement. We call it MD. Wrapping and packaging technology does not need expensive label printing equipment, while shrink wrap (TD) has high requirements for equipment

film and casing equipment

generally, the tension control of unsupported film is better than that of pressure sensitive film. Some old label printing companies or companies that insist on making pressure-sensitive films generally do not print shrink film labels

in addition to pressure control, thermal control also plays an important role in label printing. The printing machine must have sufficient heat dissipation capacity to prevent film shrinkage during printing. For shrink film, heat source is the biggest enemy; We must always pay attention to the contact between the film and the overheated heat source. In the new generation of printing machines, heat dissipation rollers are added in the printing process to help eliminate heat

bonding part, which is a joint part of the tube. In a link after printing, the film is formed into a cylinder, and glue is applied at the place where both sides coincide (forming a tube); Then put the flattened casing back in place

forming and checking joints is a labor-intensive work, which is the most important step in the casing process. The ink, dust and dirty spots at the seam must be removed so that the adhesive can bond better. When the film shrinks in the container when heated, be sure to check whether there is cracking when the interface shrinks

the price of bonding equipment ranges from 40000 to 200000 dollars. The more expensive ones are equipped with a monitoring system. If you buy the monitoring system alone, the price ranges from $30000 to $50000

labeling equipment

in the manufacturing process of the sleeve, the next step after label printing is packaging. Generally, this process uses special equipment to stick labels on containers, although some manufacturers will complete it manually

high end labeling equipment can be sold for $500000

labeling equipment, first open the film, punch holes (if necessary), cut to a suitable length, and then put it on the container. Heat the film through steam, infrared or hot air to make it tightly fit with the container

wrapping products use traditional equipment to stick labels coated with adhesive on containers. Different technologies require different adhesives and heating pipelines. In the process of shrinkage, because the pressure is applied to the adhesive at the film to film contact point, hot-melt adhesive is required (in some cases, solvent adhesive is required). Although UV adhesives have a bright future in the era of low shrinkage, there are few successful cases

generally speaking, polypropylene is the only material that can be used for wrapping printing. It is only suitable for a material with a maximum shrinkage of 20%. Hot melt adhesive is more suitable for this material, while solvent adhesive will wrinkle polypropylene. Due to the high starting temperature of thermal shrinkage of polypropylene. Generally, pressurized air flow shrinkage oven will be selected to make it shrink

chemical composition of shrinking ink

the friction coefficient of ink plays a very important role in the application of sleeve labels, which determines the efficiency of labels sliding through containers. Generally, there are few inks suitable for flexographic printing

environmental friendly water-based ink not only has great elasticity, but also has a shrinkage rate of more than 40%. It costs less than UV ink and is less affected by the movement of atoms in chemical molecules

similar to water-based inks, solvent based inks also have strong elasticity and shrinkage of more than 40%. The drying of solvent based inks is also less disturbed by moisture, but it is more affected by the movement of atoms in chemical molecules

uv free radical ink can cure immediately. This kind of ink is affected by oxygen rather than water. Generally, the shrinkage of UV free radical ink is less than 20%. On some printing materials, its adhesion is limited. Two kinds of free radical inks, which are generally scaly, have been introduced to the market

the ink starts the hard curing process after absorbing ultraviolet light with photosensitizer

2. The electron beam produces polymerization, eliminating the dependence on photosensitizers

for most substrate materials, UV cationic ink can be applied, and its shrinkage can exceed 40%. This kind of ink is also very elastic. In addition, this kind of ink can cure almost instantly, but the price is much more expensive than UV free radical ink

advice on prepress design

it is expected to be officially put into production in the first half of this year. For prepress designers of shrink labels, we must consider the shape of the container and try not to put the key image on the shrinkage, which has also become the only way for the sustainable development of rubber. Another is to consider where to place the barcode. Bar codes are usually printed vertically to prevent image distortion and affect scanning

many computer programs can interpret distorted images, but in some cases (especially low shrinkage applications), once the image is distorted, it will be regarded as waste

knowledge about shrink film

the thickness of a typical shrink film is 50 μ M. in the past few years, it is relatively thin, with a thickness of about 40 μ m~45 μ m。 The thickness of the film used depends on the type of label printer. It is generally recommended that label printers buy some expensive shrink films, which have strong shrinkage

although the shrink film is designed to shrink in a specific direction, it will also shrink a little in the opposite direction. Since the shrink film is sensitive to heat, care should be taken about the temperature during storage, printing and transportation of the shrink film. Most film manufacturers recommend that the film should be stored in an easily controlled environment. The storage temperature should be between 21 ℃ and 32 ℃ immediately before the label is affixed to the container

the minimum shrinkage rate required by the container obtained through calculation is used as a reference for the shrinkage requirements of the film, and the shrinkage rate of the film cannot be lower than this value. If the diameter of a container will suddenly change, the film with strong shrinkage must be selected

in order to calculate the printing width of the label, the maximum width of the container can be added with two overlapping widths. Another 4mm should be added to the sleeve, so that the sleeve can slide on the container

pvc (polyvinyl chloride), 2/3 of the shrink films used now are PVC shrink films. The reason why PVC is valued in the industry is that its shrinkage capacity is maintained at 40% - 60%. At the same time, its cost is low and its strength is very high. It is suitable for multiple packaging and edge banding of anti-theft devices

however, the environmental pollution caused by PVC cannot be ignored. Plastic container recyclers generally do not accept PVC in the recycling process, especially separating them from PETG (ethylene glycol polyester) containers. Because the proportion of PVC and PETG is close to 1.33, it is difficult to separate them in the recycling process with today's technology

petg (ethylene glycol polyester), with a shrinkage rate of 78%, was previously considered as a substitute for PVC, with a market share of about 15% - 20%. Now, the market of PETG is growing, while PVC is going backwards. However, the higher raw material cost of PETG hinders further development, especially when newer and more competitive materials enter the market

ops (oriented polystyrene) has become the preferred substrate material in many countries all over the world. Ops is more environmentally friendly than PVC and more economical than PETG. The shrinkage capacity of OPS is as high as 65%, which is comparable to other films with high shrinkage. The proportion of OPS is 1.025, and the income advantage is 20% higher than that of PVC and PETG. Another advantage of using OPS is that it contracts little or no in the opposite direction

opp (oriented stretched polypropylene) has poor shrinkage, but it occupies a place in the wrapped shrink film market, with a market share of 18% - 20%. Opp is suitable for liquid crystalline polymers. It refers to high molecular materials that can form liquid crystalline state under certain conditions, which have low shrinkage and are close to cylindrical containers. The specific gravity of OPP is 0.90. The price is competitive and the output is large, which has successfully blocked the entry of other printing materials

when printing on a white OPP surface, something else needs to be added to prevent friction. Opp is different from the printing materials mentioned earlier. It is specially designed for packaging

future films

nowadays, several companies are studying potential non Petrochemical environmental protection films. This kind of film is even used as the basic material of containers. This material is PLA (resin), which can be completely used as compost and can be decomposed by organisms. Due to the rising production price of petrochemical products, PLA, a substrate material, can naturally become another option. Although this kind of printing material is a little over present

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