Film adhesive material UV glazing instead of lamination
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
The film material is a non-absorbent material, and the surface energy (surface tension) is low. If the surface is not subjected to some pretreatment and the surface tension is increased, it is difficult to achieve the desired ink by using a general ink regardless of which method is applied. The wet state, that is, the ink is difficult to achieve a good degree of firmness, and the ink layer peeling cannot be avoided.
To this end, in order to improve the firmness of the ink layer on the surface of the film material, the printing industry generally adopts a corona treatment or a method of pre-coating an ink-repellent coating on the surface thereof to ensure the firmness of the ink. After surface pretreatment, the firmness of the ink layer on the surface of the film is greatly improved. According to the usual testing methods of the printing industry, whether the tape test or the friction test is used for the friction test, the results are in compliance with the standards promulgated by the domestic standard department. For example, the firmness of our film label sample inks has been tested by the National Packaging and Decoration Quality Testing Center according to the national standard GB-7706-87 inspection standard. At the same time, some customers have their own testing methods (such as some Taiwanese printing factories in China), use their own instruments to detect their printed film material labels, and the ink layer's anti-friction ability and related indicators are fully qualified.
However, although the ink firmness of the film material label has been tested, the scratch resistance of the ink layer has not been fundamentally solved in practical applications. For some cosmetic customers in China, the plastic bottles after labeling are placed directly into the package, and no separators or fillers are placed between the bottles, and then shipped to various places for sale. During the transportation process, the bottles collide and rub against each other, and finally the ink on the surface of the bottle label is seriously worn and cannot be sold normally.
In order to solve this serious problem of ink layer wear, in addition to the measures taken by the end customer in the way of packaging the product, the printing factory usually solves in three ways.
Screen printing directly on the bottle
Screen printing, because of the use of special inks and thick ink layers can solve the problem of scratching and abrasion of ink, but screen printing is only suitable for ordinary text, color block and line printing. For high-resolution color patterns, screen printing cannot be achieved. Can not achieve the packaging and decoration effect of the product.
In addition, after the screen printing, the pattern on the surface of the bottle is difficult to remove, and it is difficult for the customer to do the quantitative printing processing of the bottle. The number of bottles printed will be too large or not enough, which will bring the customer Unnecessary waste. Therefore, the screen printing method prints the bottle body, which is only suitable for simple and mass-produced products, and is difficult to promote on high-grade daily products.
Composite BOPP film and protective ink on printed film adhesive label surface
The surface of the label is laminating and protecting the ink to solve the problem of ink layer wear. This kind of process is widely used in some ink factories in China, and has received certain effects, but it also brings some negative effects. According to our recent visits to customers, research and research, the shortcomings of the membrane process are summarized as follows:
First, the finished product label increases the cost and the customer increases the cost.
The price of the film self-adhesive material itself is much higher than that of ordinary paper label materials, and the BOPP film used for laminating the film surface should be made of high-grade materials with good transparency and small tensile deformation, and the average price is 3~. Between 5 yuan, this increases the overall cost of the sticker, and the customer increases the cost.
Second, changed the physical properties of the film self-adhesive material
The BOPP laminating material is a biaxially stretched film material which is substantially non-deformable in itself, and there are many varieties of non-adhesive film materials, each of which has different characteristics. If it can be uniaxial tensile deformation (Primax, FasClear), and some can be biaxial tensile deformation (PVC, PE). Such materials, such as BOPP film, lose their own characteristics, change physical properties, and cannot be applied to deformable bottles, such as cosmetic or shampoo plastic bottles.
Third, thicken the thickness of the label, generate internal stress, increase the possibility of label lifting, falling off
The BOPP for laminating is generally about 15 μm. Regardless of which laminating mechanism is used, it is necessary to give BOPP a certain tension to make it conform to the surface of the label. Under the action of tension, the composited label produces an upwardly raised internal stress, so the possibility of outward warping is increased regardless of whether the label is applied to a flat or curved bottle.
In addition, the thinner the overall label, the smaller the internal stress after deformation, and the stronger the adhesion under the action of the adhesive. After the lamination, the label is thickened. After the deformation, the underlying material is squeezed and the above laminating material is stretched. They all have internal stresses to restore deformation. Therefore, the probability of the label after labeling is very high. Large, especially if the temperature of the label is too low, the fluidity of the glue is poor, or the label surface is not fully compressed.
Fourth, the laminating process produces a large amount of static electricity, which brings difficulties to the printing process and the final application of automatic labeling by customers.
The plastic film material is a very unstable material, which generates static electricity during printing, and the combination of the two film materials generates a large amount of static electricity. This kind of static electricity causes troubles in printing and processing, especially in the die-cutting waste disposal station. Static electricity causes the labels to fall off frequently, and the machine cannot be produced at high speed. More seriously, the static electricity remaining in the finished roll can affect the normal use of the label. For example, the label is not properly marked and skewed on the labeling machine, and sometimes even the labeling machine cannot operate normally, and can only be manually labeled, which seriously affects production.
Fives, The laminating process affects the speed of the machine and increases the overall consumption.
The tension of the laminating film is proportional to the speed of the machine, so the speed of the machine during lamination is limited. Generally, the laminating speed is 30m/min on the domestic rotary labeling machine, and the lamination is not laminating and only printing (glazing). When the machine (flexo machine) is color-printed, the speed can reach 80-100m/min. That is to say, the lamination process is inefficient.
At present, the maximum length of BOPP composite film that can be purchased on the market is 200 meters, which means that the label machine must stop and replace the composite film every time it runs less than 200 meters, so the machine is opened and stopped. According to the printing principle, when the printing machine is stopped and turned on, the inking system changes, the amount of ink of the printing material changes, and finally the color of the label changes, and waste products appear. This is one of the reasons why the laminating process is expensive.
Sixth, UV glazing process and protective ink on the surface of the film material
The UV glazing process is currently used in the domestic label printing industry, and the half-round transformation labeling machine usually adopts a method for paper or film materials to protect the ink. The UV glazing process improves the brightness of the printed surface, and more importantly, protects the ink layer and prevents the ink from being scratched and detached by its strength and anti-friction properties.
Compared with the laminating process, although the strength of the glazing oil is not as good as that of the BOPP film and the finished label, it has obvious advantages in comprehensive characteristics.
Seven, reduce the overall cost of label prints
The cost of the UV glazing process is much less expensive than the cost of the BOPP composite film compounding. At present, there are many types of UV coatings in China, and the performance is different, so the price difference is large. We recommend our customers to use high gloss, scratch resistant, low shrinkage, fast drying and high strength glazing. The price of this kind of glazing oil is generally about 150-200 yuan/kg, and it is 2g per square meter. The cost per square meter is 0.3-0.4 yuan, and the price is about one-tenth of the price of composite film. Said to reduce the overall cost of label printing.
Eight, does not change the physical properties of the film material
The UV varnish has a thickness of 2 to 5 μm after drying, and is integrated with the ink layer, which has little effect on the overall thickness of the label. The film material after glazing does not affect its own deformation and bending ability due to the glazing layer. , maintaining the flatness of the label itself. The same UV glazing process avoids the deformation of the material itself, causing the label to peel off on the packaging bottle body, which is one of the reasons why some domestic end customers choose the glazing process.
Nine, no static electricity will be generated
The UV glazing process basically does not generate static electricity. On the contrary, a “static removing agent” can be added to the varnish, which can eliminate the static electricity on the surface of the printed matter, so that other processing steps after glazing can be smoothly performed, such as die cutting and arranging. Waste, cut or rolled. When the end customer uses the label, there will be no various labeling problems caused by static electricity.
Ten, can quickly glaze online, improve productivity, reduce consumption
The speed of the printing press is not affected by the glazing process and can be quickly printed. Generally, the flexo machine has an average speed of 60-80 m/min when printing complex graphic labels, and does not need to stop the paper during the middle of the process. The speed of the laminating process is 30-40 m/min, and the composite film is frequently changed for the impact. Registration and ink uniformity. When used, the glazing process improves efficiency and reduces consumption.
In summary, in order to protect the ink layer on the surface of the film and improve its scratch and abrasion resistance, among the three methods adopted in the label printing industry, the UV glazing process is the best comprehensive effect. At present, the in-line glazing process is commonly used in developed countries, and the lamination process is rarely used unless requested by the customer. The same is true in China. In the areas where label printing is developed, such as Shanghai, Guangzhou, Tianjin and other large professional self-adhesive label printing plants, UV glazing is widely used.
To this end, we promote and promote the use of UV glazing to protect the ink layer after printing on the surface of the film sticker. For the glazing process, after several years of hard work and summarizing the practice of the printing factory, especially in the past one or two years, through our company training center on the arsoma flexo machine and IGT printing suitability test, we have summarized a lot of experience. . These experiences include the selection of UV coatings, the control of printing speed, the adjustment of drying and curing power, and the control of glazing coatings. These experiences have now been successfully applied in some printing houses. The samples we tested were generally recognized by some large cosmetic customers.
To further illustrate our experience, we will first introduce the basic methods of UV glazing in the domestic label industry;
Using UV letterpress machine and offset printing machine (post-cure), the direct printing light layer is thin and the gloss is poor. It can be glazed on a single sheet or a roll, and can be partially or totally glazed, and the viscosity of the glazing oil is large.
Coating glazing is applied by a two-roll or three-roll apparatus. It can be installed on the label machine for simultaneous operation and is suitable for web. It can also be used as a glazing machine for glazing, suitable for sheetfed. The glazing is low in static electricity, and the glazing layer is affected by the speed change and the accuracy of the glazing device. The varnish has low viscosity and is suitable for overall glazing.
The advanced glazing principle of the flexo machine glazing uses the mesh stick to precisely control the amount of glazing, which can be partially or totally glazed, and the viscosity of the glazing oil is low.
To ensure UV glazing quality, we have summarized three experiences:
First, use the same UV varnish and additives as the ink, otherwise it will affect the firmness of the glazing layer or the chemical reaction between the ink and the varnish.
Second, the use of high-quality, scratch-resistant high-grade glazing oil for film materials, because of the special additives in this varnish, can improve the resistance of the glazing layer and protect the ink layer.
Third, the ink and glazing oil must be dried and cured thoroughly, otherwise the firmness and scratch resistance level will not reach the maximum extent. The qualified customers can arrange multi-station drying to ensure the ink and glazing oil dry out.
The above theoretical and practical experience discusses the reasons and importance of the UV glazing process instead of the lamination process, and also lists the domestic successful experience. Finally, we believe that as long as the printing and final customers actively cooperate with our material suppliers and ink suppliers, we will realize the UV glazing process instead of the laminating process, which will bring benefits to everyone.