About the author: Roger Brown is the marketing manager of Plastic Suppliers Inc., Columbus, Ohio.
Today, flexographic label printers face increasing competition, so they are all entering the shrink label market. The shrinking label market is new and has large growth potential. It is also different from the label market that is relatively less restrictive and easy to join, so it can prevent new companies from joining the competition. Traditional flexographic printers have begun to purchase shrink label technology devices, including: splicing machines and new printing presses, the annual growth rate is expected to reach 7 to 10%, which is higher than the general standard of only 4 to 5% growth rate The sticker market is high.
Region-based products and patented products rely on packaging design to attract customers' attention, which opens the door to the small and medium-sized label market. The market development of ethnic foods, organic foods, and healthy foods, as well as the labeling regulations of the US Food and Drug Administration, have increased business opportunities in the labeling market.
According to industry statistics conducted by the Business Development Association of Bethesda, Maryland, the amount of film used in the local shrink label market in 2003 reached 49 million to 53 million (approximately US $ 300 million). Intaglio printing occupies this market, and it is estimated that only 15% of shrink labels are printed on flexographic plates.
When to enter the label market
The number of patented food and regional product projects is increasing, which increases the diversity of market management items. This emerging phenomenon makes the shrink label work seamlessly with the flexographic printing industry, which is still in its infancy. The quality of flexographic printing is not only constantly improving, but also its pre-press cost is lower than that of gravure printing. This is an important factor for flexographic printing to be suitable for the label market.
If you plan to enter the flexible label market, you can refer to the recent industry research report. It is estimated that narrow print rolls are preferred for printing volumes below 40 million square inches; wide roll rolls are preferred for printing volumes greater than 40 million square inches. (see picture 1)
For example, if a forty-inch wide-width reel is used, the profit-loss balance point between flexographic wide-width web printing and gravure printing is about 500,000 meters. This number depends on many factors, including: the cost of capital equipment and the cost of placement.
Two very different markets
The shrink label industry is divided into two distinct markets: heat shrinkable sleeves and ring cans. Both can be printed with flexographic printing and the quality is just as good.
The transverse shrinkage characteristic of the film is referred to as TD. First, the shrink film traverses the wide edge of the reel to form a tube, which is placed on the container. Then the film shrinks laterally when it is heated, and the film will cling to the container.
The characteristic of the longitudinal positioning of the ring-shaped film is referred to as MD, which means that the film shrinks longitudinally when it is heated. Heat-shrinkable tube technology requires bottling companies to purchase expensive shrink-labeling equipment to match, but the ring tank technology is not.
Film and casing equipment
Generally speaking, when printing with unsupported film, tension control should be better than printing with pressure sensitive film. Some old-fashioned printing houses or companies determined to operate pressure-sensitive label businesses usually do not switch to shrink labels.
To print high-quality labels, in addition to tension problems, thermal control is also an important factor. The printing machine must have high heat dissipation ability to prevent the film from shrinking during printing. Heat is the biggest enemy of shrinking the film, so all measures must be taken to prevent the film from overheating. The new generation of printing presses incorporate freezing drums to remove heat during the printing process.
Sets of labels require joining equipment. The bonding equipment forms a flat printing paper roll into a tube, and then bonds the overlapping parts (forming the interface). Then, put the flattened sleeve back.
Manufacturing of manufacturing interfaces and monitoring interfaces requires a high degree of labor intensity. During the joining process, if an important step goes wrong, the resulting error will delay the subsequent process. The parts that need to be joined must be cleaned of ink and contaminants so that the adhesive can be properly bonded. The manufacturing process of the joint must be 100% monitored to prevent the film from bursting when it shrinks on the container.
The bonding equipment is from 40,000 to more than 200,000 US dollars. The higher price is supported by a monitoring system. If the monitoring device is purchased independently, an additional payment of US $ 30,000 to US $ 50,000 is required.
Labeling equipment
In sleeve production, the next process of label printing is packaging. Although packaging companies sometimes use manual labeling, they usually use special labeling equipment to label the containers. Advanced labeling equipment can be as high as half a million dollars.
The labeling equipment opens the bonding film, pierces (if necessary), and then cuts the label across and places it on the container. Then, heat is transmitted through the steam, infrared or pressurized airflow thermostat, so that the film is tightly attached to the container.
The ring-shaped film uses conventional equipment to attach the label to the container. Different technologies require different adhesives and thermostats. During the shrinking process, pressure is applied to the adhesive at the film-to-film contact point, so hot-melt adhesives are required (in some cases, solvent-based adhesives). In the past, when low shrinkage was needed, the use of low shrinkage UV adhesives seemed good, but so far there have been few successful examples.
Roughly speaking, the only printing material that can be used as a ring can film is polypropylene. Because its upper limit of shrinkage is 20%, hot-melt adhesives work very well, while solvent-based adhesives can wrinkle polypropylene. Due to the higher shrinkage temperature curve of polypropylene, the compressed air flow shrinking thermostat is the main type of thermostat used because it can reach a higher temperature than the steam thermostat.
With more films with higher shrinkage entering the market, solvent-based adhesives will need to resist the high shrinkage force of the interface.
Shrink ink chemicals
The coefficient of friction of the ink plays an important role on the sleeve label. The efficiency of the sleeve sliding on the container depends on the coefficient of friction. Very few ink chemicals are suitable for flexographic printing.
Environmentally friendly water-based inks can shrink by more than 40%, are very flexible, and cost less than UV inks. Moreover, the ink surface is less affected by the movement of atoms in chemical molecules.
Solvent-based inks are similar to water-based inks, with great elasticity, which can shrink by more than 40%. The drying time required for solvent-based inks is less affected by moisture, but it is slightly affected by the movement of atoms in chemical molecules. For most films, the adhesion of solvent-based ink is the largest.
UV free radical ink can be hardened instantly, this ink is inhibited by oxygen rather than moisture. Generally speaking, the shrinkage is less than 20%. In some printing materials, its adhesion is limited. The surface of the ink may show the movement of atoms in the chemical molecules. Two free radical inks are now available on the market:
UV uses a sensitizer to absorb ultraviolet light to start the hardening process.
The electron beam produces polymerization, eliminating the use of photosensitizers.
UV cationic ink can produce adhesion in many kinds of printing materials, and its shrinkage rate exceeds 40%. This ink tends to be more elastic. In addition, this ink hardens almost instantaneously, and atoms in chemical molecules move less, but the price is also more expensive than UV radical ink.
Graphic design advice
The graphic design of the shrink label needs to consider the appearance of the container, and try not to put the key image in a place with high shrinkage. Another factor to consider is where to place the barcode. Bar codes are generally printed vertically to prevent image distortion and affect sketches.
A series of computer programs can interpret distorted images, but remember that in some cases (especially low shrink printing), distorted images are useless.
About shrink film
The thickness of a typical shrink film is within fifty microns (one thousandth of an inch). In the past few years, thinner shrink films with only 40-45 microns have been introduced. The label processing performance of the equipment used by label manufacturers determines the acceptable shrink film thickness. In general, label manufacturers can expect higher shrinkage films to be more shrinkable.
Although the shrink film is designed to shrink in a specific direction, there will be some shrinkage in the opposite direction. Since the shrink film is sensitive to heat, it is necessary to pay attention to the storage, printing and transportation temperature of the shrink film. Most film manufacturers recommend that the film be stored in a controlled environment at approximately 75-85 degrees Fahrenheit until it needs to be labeled on the container.
The mathematical program is used to determine the minimum shrinkage required for a particular container. The resulting value is used to determine the shrinkage demand for the film. The shrinkage of the film must not be lower than this value. If the diameter of a container changes suddenly, it will greatly increase the demand for printing materials with higher shrinkage.
To calculate the required width of the printed label, the width of the container's widest position can be added twice to the width of the overlapping interface; the sleeve must be added 4 mm to allow the sleeve to slide on the container.
PVC (Polyvinyl Chloride)-Two thirds (approximately 34 million pounds) of shrink films currently used are PVC shrink films. PVC has gained importance in the industry. The shrinkage rate of PVC shrink film is maintained at 40% to more than 60%. The high shrinkage rate and low cost are the choice of many companies in the United States. The strength of PVC makes it suitable for multiple packaging and edge banding of anti-theft devices.
Figure 3: â—Ž Plastic Suppliers Inc.
However, PVC continues to cause environmental problems. Plastic container recyclers like to exclude PVC during the recycling process, especially to separate them from PETG (polyester) containers. But since the proportions of PVC and PETG are close to 1.33, with today's technology, it is really impossible to separate the two in the recycling process.
PETG (polyester film) has a shrinkage rate of up to 78%, and was previously considered to be a substitute for PVC. The market share of polyester film is about 15-20%. The PETG market is growing, but the PVC market is not. PETG has a specific gravity of 1.28, making it comparable to PVC. However, the higher raw material cost of PETG hinders its market growth, especially the entry of newer and more competitive materials into the market.
OPS (polystyrene film)-relatively new in the US domestic market, but has become a preferred printing material for many users around the world. OPS is more environmentally friendly than PVC and more economical than PETG. OPS currently has a 5% share of the US domestic market, and its apparent growth rate is just around the corner.
As OPS shrinks by up to 65%, it can rival other high shrink products. The proportion of OPS is 1.025, and the revenue advantage is 20% higher than that of PVC and PETG. Another benefit of using OPS is that it shrinks very little or not in the opposite direction.
Although OPP (polyvinyl chloride) is not highly shrinkable, it has a share in the ring-type shrink film market, with a market share of 18% to 20%. OPP is suitable for containers that require low shrinkage and are nearly cylindrical. The proportion of OPP is 0.90, the price is competitive, and the output is large, which prevents other printing materials from entering this targeted market.
For printing on the white OPP surface, a coating is required to resist abrasion. The difference between OPP and other printing materials mentioned above is that it is specially designed for ring tank type.
The film of the future
Today, several companies are studying the potential of non-petrochemical environmental protection films. This film was even tested as a basic material for containers. This material is PLA (resin), which can be used as compost and can be decomposed by living things. Due to the rising production prices of petrochemical products that industry relies on, printing materials such as PLA has naturally become another option. Although this printing material is a bit ultra-modern, it should be introduced to the market sooner than expected.
To enter the shrink film market in a timely manner, it takes effort. In the long run, investment in this market should be profitable. However, the important technical issues cannot be solved independently, so your production team must include printer manufacturers, ink and film suppliers.
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