Laser promotes the growth of film packaging industry
the emergence of small, sealed CO2 lasers and the development of shorter output wavelengths are promoting the growth of film packaging industry
the sealed CO2 laser technology is developing continuously, the performance is improving, the reliability is increasing, the volume is decreasing, and the total cost of the laser is decreasing. As a solid and reliable tool, sealed CO2 lasers are widely used in industry. One of the latest applications is flexible packaging, that is, paper, plastic film and other materials are folded into a preset packaging shape. This paper mainly introduces how the recent progress of CO2 laser technology promotes the rapid growth of food laser flexible packaging market
laser flexible packaging technology
the flexible packaging used for processing food and beverages can adopt a variety of forms and shapes, including envelopes and bags, especially the packaging that can be resealed is developing rapidly. Most of these packages use film materials, such as polyester (PE), aluminum foil and polypropylene (PP) - usually biaxially oriented polypropylene (BOPP). Usually, these materials should be combined to form a two-layer or multi-layer composite structure. The most common thin-film synthetic material is double-layer PP and PE, which are rolled together. The rapid growth of orders reflects that the demand explosion is still continuing. Among them, PE is a barrier layer, which is in direct contact with food, and the PP layer with graphics is outside, which is a printing layer. The whole film thickness is about 100 microns, even for bag packaging that can stand up. During the packaging process, the film wound on the drum moves forward continuously due to the rapid rotation of the drum. At this time, laser is used to cut and trim the film, or notch and drill holes on the film. For example, laser scoring can make the packaging bag easy to open, and laser drilling can make the packaging bag breathable
compared with traditional machining methods, the advantage of non-contact laser processing is that there is no tool wear problem and the consistency of products is improved. In addition, flexibility is also very important, because today's product production cycle is very short. Machining, including tool costs, is not suitable for short-term operations, and is not suitable for changing back and forth between different film types and packaging forms. Due to the real-time control of laser parameters, the flexibility of laser processing and packaging can enable producers to obtain consistent scoring results, even when the film thickness changes
it is obvious that in business areas with large output/low profit, such as film packaging, the reliability and total cost of laser are key issues for owners to consider. The small size of lasers is also very important because they can be assembled into packaging equipment. In terms of laser output power, these applications usually require only 30 to 100 watts of power, because the multilayer structural materials to be processed are usually very thin
these characteristics make today's small CO2 lasers an ideal tool for the folding flexible packaging market. The low-power sealed diamond CO2 laser produced by coherent company has the characteristics of high reliability, low cost per watt and small volume. Its size is as large as an ordinary shoebox (see Figure 1). These foldable waveguide lasers are ideal tools for processing plastic (polypropylene and polyester) films at a processing speed of more than 300 meters per minute (1000 feet per minute). In addition to providing cheap solutions for medium power applications, the small size of the new laser also makes it possible to arrange multiple lasers on a wide drum (such as a 1.5 meter/60 inch wide main drum), thus providing unprecedented processing flexibility for flexible packaging. Moreover, these lasers do not need maintenance, and their service life is between 10000 and 20000 hours, which can fully meet the needs of typical high-yield packaging equipment
the progress of small CO2 lasers in other output wavelengths is another important factor that has a significant impact on the food flexible packaging market. The reason is that the infrared absorption spectrum of most polymer films contains several peaks. Therefore, small changes in laser wavelength may have a great impact on the absorption coefficient, because the thin films used in flexible packaging are very thin, and usually only a small part of the laser power can be absorbed. Therefore, by adjusting the wavelength to increase the absorption coefficient of the film, the processing speed at a given laser power will be greatly increased
the output wavelength of most CO2 lasers is concentrated at 10.6 microns. However, if wavelength selective optical elements are inserted into the folded cavity structure, other wavelengths, such as 10.2 microns, will be generated. Coherent application laboratory recently studied the effect of commercial 10.2 micron lasers on thermoplastics, and the results were published in document 1. For unexpanded polypropylene film, there is only a small difference in processing speed when using 10.6 and 10.2 micron laser processing. However, the difference is very obvious for the commonly used BOPP film (micron thickness)
in addition, using different carbon dioxide isotopes can shift the laser output wavelength further, which will have an important impact on other applications. For example, coherent has found that when processing Kapton (polyimide) films commonly used in electronics and other industries, 9.4 micron wavelength laser can produce the best results
multiple laser combinations
Alcan Packaging (Chicago, IL) is a major supplier of flexible packaging equipment. Its products are mainly used in the packaging market of meat, dairy products, fruit juice, and health and beauty products (see Figure 3). As early as 1985, the company began laser marking thin films. Now, it uses sealed CO2 lasers for flexible packaging of thermoplastic and metal foil. Finnian flood, senior engineer of Alcan Packaging, explained, "the emergence of small and solid CO2 lasers enables us to use them for slitting, punching and scoring instead of templates and other mechanical tools. We often use them on huge drums (up to 400 mm/15.75 inches wide) Make smaller bags in. Today's sealed lasers are very small, which is conducive to their use in wider reels. In this case, we use multiple lasers and a fixed optical system to cut and score along the drum. There is also a line that uses an optical system to allow the beam to scan laterally on the drum to produce complex shapes "
now, you can buy several sealed CO2 lasers with more than 500 watts. Why not use them and use multiple low-power lasers
laser digital flexible packaging
lasx industries has become a leader in the field of laser flexible packaging since its opening in 1998. The company provides lasersharp flexible packaging solutions and contracted processing. Bill dinauer, the founder and chairman of the company, explained: "For us, it seems very clear that flexible packaging in the United States cannot keep pace with machining indefinitely.
now, the production cycle is so short that only ensuring the flexibility and accuracy of motion mechanisms such as pendulum can not prove that the use of flexible packaging technology is absolutely justified. In addition, the emergence of sealed CO2 lasers has made 'digital flexible packaging', that is, computer-controlled laser flexible packaging possible.
lasx Most of the flexible packaging equipment sold by the company is the renovation of the existing coiler rewinder. This cost-effective strategy is to combine the existing functions of the coiler rewinder with laser digital flexible packaging technology, such as laser scoring, punching, etc. Therefore, new functions are added without increasing labor and time. Now, there are two new structures: one is to use multiple lasers to process the film material on the drum with a fixed beam, which is similar to Alcan Packaging equipment; Another form is dynamic (based on scanning), which allows the beam to scan across the drum. Here, the laser beam can scan the film material on the drum horizontally and longitudinally to produce any required pattern. The number of laser components can vary according to the width of the drum, the complexity of the pattern and the spacing of repeated patterns. A typical scanner machine contains two and four laser components. Lasx has incorporated its equipment into digital packaging printers for narrow reels such as labels
conclusion: for the processing with large output and small profit like flexible packaging, the existing small sealed CO2 laser has the comprehensive advantages of low cost, high reliability and small volume. Laser flexible packaging equipment can be added to the production line to achieve the purpose of minimum cost and labor input. Because there are many films and organic polymers used for packaging, it will make these lasers more attractive for system suppliers and manufacturers of similar packaging equipment if they can operate at the best wavelength
source: China Industrial Equipment
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