The hottest film self-adhesive material UV glazing

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Thin film adhesive material UV glazing instead of lamination

thin film material is a kind of non absorbent material with low surface energy (surface tension). If the surface is not pretreated and the surface tension is increased, it is difficult to achieve the ideal wetting state of the ink no matter which method is used for printing, that is, it is difficult for the ink to achieve good firmness, and the ink layer falling off cannot be avoided

therefore, in order to improve the firmness of the ink layer on the surface of film materials, the printing industry generally adopts corona treatment or pre coating the ink friendly coating on its surface to ensure the firmness of the ink. After surface pretreatment, the firmness of the ink layer on the film surface is greatly improved. According to the usual detection methods in the printing industry, whether the tape test or the friction resistance test is carried out with a friction tester, the results meet the standards issued by the domestic standards department. For example, the ink firmness of our film label sample has passed the national packaging and decoration quality inspection center, and has been tested according to the national standard GB inspection standard. At the same time, some customers have their own testing means (such as some Taiwan printing plants in China) and use their own instruments to test their printed film material labels. The friction resistance of the ink layer and relevant indicators are completely qualified

however, although the ink firmness of film material labels has passed the inspection, the scratch resistance of the ink layer has not been fundamentally solved in practical application. For example, for some domestic cosmetics customers, the labeled plastic bottles are directly put into the packaging box without any partition or filler between the bottles, and then transported to various places for sale. In the process of transportation, the bottles collide and rub with each other, resulting in serious wear of the ink on the surface of the bottle label, which 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 on the product packaging, the printing factory usually adopts three methods to solve it

■ silk printing is directly used on the packaging bottle.

silk printing can solve the problems of ink scratch and wear due to the use of special ink and thick ink layer, but silk printing is only suitable for ordinary text, color block and line printing. For high-resolution color patterns, silk printing cannot be achieved. It cannot achieve the packaging and decoration effect of the product

in addition, it is difficult to remove the patterns on the surface of the bottle body after silk printing, and it is difficult for customers to achieve quantitative printing processing of the packaging bottle body, resulting in excessive or insufficient bottle body printing, which will bring unnecessary waste to customers. Therefore, the printing of bottle body by silk printing is only suitable for simple and mass-produced products, which is difficult to promote in high-grade daily chemical products

■ compound BOPP film and protective ink on the surface of the printed film self-adhesive label

compound film on the surface of the label and protect the ink to solve the problem of ink layer wear. This process is widely used in some domestic ink factories, and has received certain results, but also brought some negative effects. According to our customer visits and investigations in recent years, the shortcomings of the membrane process are summarized as follows:

first, the finished 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, while the BOPP film used for laminating on the surface of the film should choose high-grade materials with good transparency and small tension deformation, with an average price of 3 ~ 5 yuan, This increases the overall cost of self-adhesive labels, and customers increase costs

second, it has changed the physical properties of film adhesive materials

bopp laminating material is a kind of biaxially stretched film material, which basically does not deform itself, while there are many varieties of adhesive film materials, each of which has different characteristics. For example, some can be uniaxial tensile deformation (primax, FasClear), and some can be biaxial tensile deformation (PVC, PE). This kind of material, such as BOPP film, loses its own characteristics and changes its physical properties. It cannot be applied to the preformed solid composite parts of the finished product, such as plastic bottles of cosmetics or shampoo, which are automatically cut

III. the thickness of the label is thickened, internal stress is generated, and the possibility of label warping and falling off is increased.

BOPP for lamination is generally 15 μ M, no matter what kind of laminating mechanism is used, a certain tension should be given to BOPP to make it fit smoothly on the label surface. Under the action of tension, the compound label produces upward internal stress, so whether the label is affixed to the flat or curved bottle body, it increases the possibility of outward edge warping

in addition, the thinner the overall label, the smaller the internal stress after deformation, and the more firmly it adheres under the action of adhesive. After laminating, the label is thickened, the lower material is extruded and the upper laminating material is stretched after deformation, and they all have the internal stress to restore deformation. Therefore, the probability of the label after laminating is very high after labeling, especially when the temperature is too low, the glue fluidity is poor or the label surface is not fully compressed during labeling

IV. the laminating process produces a lot of static electricity, which brings difficulties to the printing process and the final application of automatic labeling by customers.

plastic film material is a material with very unstable polarity, which will generate static electricity during the printing process, while the combination of the two film materials will generate a lot of static electricity. This kind of static electricity brings trouble to printing and processing, especially in the die cutting waste discharge station. Static electricity will cause labels to fall off frequently and make the machine unable to produce at high speed. What is more serious is that the static electricity remaining in the finished drum will affect the normal use of the label. For example, labels are not normally labeled and skewed on the labeling machine, and sometimes even the labeling machine cannot operate normally, so it can only be labeled manually, which seriously affects production

v. the laminating process affects the machine speed and increases the overall consumption

the tension of laminating is proportional to the machine speed, so the speed of the machine during laminating is limited. Generally, the laminating speed on the domestic rotary label machine is within 30m/min, while the speed of the rotary machine (flexographic machine) that does not laminating and only prints (glazing) can reach 80 ~ 100M/min for color printing. That is to say, the laminating process is inefficient

at present, the maximum length of bottomless BOPP composite film available on the market is 200 meters, which means that the label machine must be shut down and replaced every time it runs less than 200 meters, so the machine is on and off. According to the printing principle, when the printing machine stops and starts up, it will lead to the change of the ink delivery system, change the ink amount of the printing materials, and finally change the ink color of the label, resulting in waste products. This is also one of the reasons for the large consumption of the laminating process

VI. adopting UV glazing process and protecting ink on the surface of film materials

uv glazing process is the usual method for paper or film materials in the domestic label printing industry at present, which is used to protect ink. UV glazing technology improves the brightness of the surface of the printed matter. More importantly, it uses its strength and friction resistance to protect the ink layer and prevent the ink from scratching and falling off

compared with the laminating process, although the strength of the glazing oil is not as strong as BOPP film and the three-dimensional sense of the finished product label, it has obvious advantages in comprehensive characteristics

VII. The overall cost of label printing is reduced

the cost of UV glazing process is much cheaper than that of BOPP composite film. At present, there are many kinds of UV varnishes in China, with different properties, so the price varies greatly. We recommend customers to use polish with high transparency, scratch resistance, small shrinkage, fast drying and high strength. The price of this kind of varnish is generally about 150 ~ 200 yuan/kg. Counting by 2G coating per square meter, the cost per square meter is 0.3 ~ 0.4 yuan, which is almost one tenth of the price of composite film. Therefore, the overall cost of label printing is reduced

VIII. Do not change the physical properties of the film material

the thickness of UV varnish after drying is 2 ~ 5 μ m. Combined with the ink layer, it has little impact on the overall thickness of the label. The use of the polished film material vigorously promotes the intellectualization and greening of the material production process. The transformed material will not affect its deformation and bending ability due to the glazing layer, and maintain the flatness of the label itself. Similarly, the UV glazing process avoids the phenomenon that the label tilts and falls off on the packaging bottle due to the deformation of the material itself, which is also one of the reasons why some domestic end customers choose the glazing process

IX. no static electricity

uv glazing process basically does not produce static electricity. On the contrary, you can add "electrostatic remover" to the glazing oil, which can eliminate the static electricity on the surface of the printed matter, so that other processing procedures after glazing can be carried out smoothly, such as die cutting, waste discharge, sheet cutting or winding. When the end customer uses the label, there will be no labeling problems caused by static electricity

X. it can quickly online polish and improve productivity. Through this learning curve advantage, we will be able to reduce consumption on conventional cars in the future.

the speed of the printing machine is not affected by the glazing process, and it can be printed and processed quickly. Generally, the average speed of flexographic machine when printing labels with complex graphics is 60 ~ 80m/min, and there is no need to stop without changing paper halfway; The speed of laminating process is 30 ~ 40m/min, and frequent shutdown and replacement of composite film will affect the registration and ink uniformity. When used, the glazing process improves efficiency and reduces consumption

to sum up, in order to protect the ink layer on the surface of the film and improve its scratch and wear resistance, UV glazing process is the best of the three methods adopted in the label printing industry. At present, online glazing process is widely used in developed countries, and laminating process is rarely used, unless required by customers. The same is true in China. UV glazing technology is widely used in some large professional self-adhesive label printing plants in areas with developed label printing, such as Shanghai, Guangzhou, Tianjin and so on

for this reason, we advocate and promote the use of UV glazing process after printing on the surface of film self-adhesive labels to protect the ink layer. As for the glazing process, after several years of efforts and summarizing the practice of the printing factory, especially in the past oneortwo years, we have summarized a lot of experience through the repeated tests of our company's training center on the arsoma flexograph and IGT printability instrument. These experiences include the selection of UV glazing oil, the control of printing speed, the adjustment of drying and curing power, the control of glazing coating, etc. Now, these experiences have been successfully applied in some printing plants. The samples we tested have been widely recognized by some large cosmetics customers

to further explain our experience, first of all, introduce the basic methods of UV glazing in the domestic label industry

· UV relief machine and offset press (post curing) are used to directly print and polish. The Polish layer is thin and the gloss is poor. It can be polished on a single sheet or on a roll in the production workshop, and it can be polished locally or as a whole. The viscosity of the Polish oil is large

· coating and glazing use a two roll or three roll device to apply and polish. It can be installed on the label machine and run synchronously, suitable for web paper. It can also be used as a polishing machine for independent polishing, suitable for sheet fed paper. The static electricity of glazing is low, and the glazing layer is affected by the speed change and the accuracy of the glazing device. The viscosity of the glazing oil is low, which is suitable for overall glazing

· flexographic machine glazing advanced glazing principle, using the stick to accurately control the amount of glazing, local or overall glazing can be achieved, and the viscosity of the glazing oil is low

in order to ensure the quality of UV glazing, we have summarized three experiences:

first, we should use UV glazing oils and additives that match the ink,

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