The hottest single offset polypropylene in mold la

  • Detail

Single offset polypropylene in mold label

in mold label (IML) provides an economical and practical alternative for the decoration of packaging containers and container covers. Unlike self-adhesive labels, they will be integrated into the surface of the product and cannot be separated. In most cases, in mold labels will be printed by single sheet offset printing to ensure the best printing quality for this area of the label market. Next, the supplier treofangmbh will explain the production process and selection criteria of IML diaphragm

the production of in mold labels is generally understood as a processing method that has provided labels for injection molded, blow molded or thermoformed products in its final plastic mold. The special surface properties of IML diaphragm make it permanently adhered to the product. So it is usually not removable

label printing

in mold labels can be printed by different processes:

* single sheet offset printing using oxidation drying ink or UV curing ink, * rotary gravure printing, * narrow web offset printing using UV ink, * flexo printing using UV ink, * relief printing using photosensitive resin plate and oxidation drying ink or UV curing ink

the order of the above list roughly corresponds to the popularity of each process. Single offset printing is the most frequent choice because it can combine a variety of different images on a single print, and it can make excellent copies of details in its photo realistic images. If the price of reel material is favorable, it will be very useful to equip a sheet cutting machine in front of the printing machine Feida when planning to use IML diaphragm for processing

rotary gravure printing is suitable for mass production, such as labels of margarine barrels. Medium volume printing is usually entrusted to web offset printers. Die cutting can be completed online or offline, depending on the printing process

manufacture of diaphragm

polypropylene diaphragm or more accurate OPP (oriented, i.e. stretched PP) and CPP (injection molded PP) the laboratory has developed high-temperature flora diaphragm for Yucheng Fuhang company for injection molding packaging, which has been growing rapidly in the past 15 years. The most used substrate is OPP diaphragm, which is also especially used for large labels in some cases, such as the label of paint bucket

in order to manufacture CPP diaphragms, single-layer or multi-layer PP diaphragms need to be extruded through a slit die. Then the diaphragm is trimmed and usually pretreated with corona discharge to prepare for printing. Finally, the diaphragm will be wound on the reel and later cut to the required width by the customer. The thickness of commonly used diaphragms is between 80 and 100 microns

The manufacturing of OPP diaphragm is much more complicated. First, the multilayer PP film is extruded in the same way as the CPP film. For IML diaphragms, it will be common to extrude three to five layers together

different melt streams have been combined in the mold and placed on the cooling roll together. After that, the so-called preparatory diaphragm is cooled and solidified, heated again to a certain temperature and stretched in its length direction. Stretching is accomplished by rollers that rotate at different surface speeds. The normal procedure is to stretch 4 by a factor of four to five The hydraulic system should be installed safely to regulate the pressure; Diaphragm. The thickness of the diaphragm will be reduced accordingly

after stretching in the length direction, stretch the diaphragm in the transverse direction. Therefore, the diaphragm should be inserted into a so-called stretcher, in which the two edges of the diaphragm will be fixed by a series of clips. Now, heat the diaphragm again and stretch it in the transverse direction with a coefficient of eight to ten when it reaches a certain constant temperature. In treofan, IML diaphragms are usually produced with a width of seven meters

after stretching, the diaphragm is stabilized to eliminate any stress in the material, and then cooled, as it will immediately contact the roller thereafter

in order to ensure the printability, corona discharge is used to treat the surface of the diaphragm, and the surface tension is increased to about 40 Mn/m. When this process is completed, the diaphragm will be wound on a machine reel and then cut to the width required for printing or sheet cutting

properties of diaphragm used for IML (in mold label)

OPP diaphragm used for IML has special requirements for material properties. Unlike OPP diaphragms used for packaging materials, IML diaphragms are often required to be provided in the form of trimmed (single sheet) or even a single label. Therefore, IML diaphragms are usually slightly thicker than typical OPP packaging diaphragms (57 to 90 microns). Therefore, it will be very important whether the leaflets and labels of IML can be easily separated. Usually, one side of the IML diaphragm is designed as a glossy surface, while the other side is designed as a matte surface to achieve this requirement. The matt surface allows air to better penetrate between the individual diaphragms and helps to remove the individual diaphragms from the diaphragm stack. Together with special additives, the matt layer can also reduce the appearance of electrostatic charges when separating the two surfaces

for the requirement that the label should be as flat as possible (that is, there is only a minimum curling tendency), you must carefully select raw materials for each layer of the diaphragm and make the thickness of each layer match accurately. In this regard, it is also necessary to ensure that the printing process and ink system used can also eliminate unwanted curls

selection of IML diaphragm

the selection of applicable IML diaphragm will largely depend on the process used in molding the final product

in the case of injection molded products, the key influencing factors are the required appearance of the label surface (shiny or with long service life and Matt) and the shape of the product. Products with high gloss labels can only be produced with large weight OPP diaphragms (such as EWR, ETR) or CPP diaphragms (CWD, CTD). In particular, an unwelcome side effect that will be shown on OPP diaphragms is that when used for thin-walled, asymmetric products, there will be a serious tendency to twist after injection molding. This can be avoided by choosing a diaphragm with honeycomb structure (euh). However, what is lost here as an exchange is the possibility of producing high gloss labels. But on the other hand, it will be a very simple thing for marketing experts to convert the necessary matte surface into an advantage, that is, to promote the orange peel effect as a soft tactile finish

cast PP film especially shows no effect on the deformation of injection molded products. However, due to their thick thickness, which leads to heavy weight, it is easier to use them for the production of large-scale items, such as 5 or 25 liter paint barrels, rather than for food packaging

since the pressure involved in forming blow molded products (such as HDPE or PP bottles) is relatively low, most of the materials used are diaphragms with a special sealing coating. In addition, this sealing coating will be applied in a specific mode to facilitate the escape of air between the product and the label. Tests designed for injection molding to achieve the same effect on OPP or CPP diaphragms have not yet produced reliable solutions. However, for und type diaphragms, treofangmbh is developing an alternative method to allow air to escape through permeable diaphragms. At the same time, no coating is required for this diaphragm

hot formed products face the same problems as blow molding. In the past, it has been proved that it will be very difficult to remove air from the molded product and the label surface. Earlier experiments have found a solution to punch holes in labels and strive to build smart factories. However, this method requires an additional processing step, and has the disadvantage that these holes will still be visible in the future

since 2006, new progress has been made in this field. Through the optimization of deep drawing process, the use of foil with honeycomb structure and the improvement of sealing, it is now possible to produce IML labels without bubbles. On the other hand, the surface of the label once again has an orange peel like finish. However, if breathable diaphragms such as treofanund are used, glossy labels can also be produced with appropriate coatings

Copyright © 2011 JIN SHI