Brief Discussion on Anti-counterfeiting Characteristics of IML In-Module Label and Its Printing Technology
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The In Mould Label (IML) is a special label that is bonded to the surface of the plastic bottle when the bottle is made by hot-melting solid binder, and integrated into the mold body in the mold. The most important feature of using in-mold label plastic bottles is that the label and the bottle are on the same surface, and there is no label. The color pattern is printed directly on the surface of the bottle.
First, the characteristics of the in-mold label
1. Aesthetics The traditional forms of traditional labels mainly include heat-shrinkable labels, direct-printing labels for screens, and adhesive labels based on self-adhesive labels. Direct screen printing label is to directly print the pattern and text on the container packaging by screen printing. The overall effect is good, the pattern and the text have texture, but it is difficult to reflect the delicate pattern and small by the limitation of screen printing. Text, when printing more colors, the price of direct screen printing is more expensive. As a label, the heat shrinkable film is cheaper than the self-adhesive label and the direct screen printing label, but the heat shrinkable label is easily broken, the overall image is not very good, and it is not environmentally friendly; the self-adhesive label can be perfectly perfect. Reflects the requirements of delicate labels, but its cost is more expensive than heat shrinkable film labels.
The close combination of the in-mold label and the bottle body has the overall effect of direct screen printing, and can perfectly embody delicate patterns and small characters like a self-adhesive label. Since the in-mold label is bonded to the bottle body, it is less likely to be broken and peeled off than the self-adhesive label and the heat-shrinkable label, and the label can be kept intact and beautiful for a long time.
2. anti-counterfeiting The use of in-mold labels requires a special mold, the production cost of this mold is higher to cost anti-counterfeiting function. At the same time, the in-mold label printing processing process is more difficult than the traditional label, thereby achieving the purpose of anti-counterfeiting technology.
3. Environmental protection There are many kinds of materials in the in-mold label. The common plastic containers have the same in-mold label materials as the components, and because the labels are combined with the containers, the recycling rate of the bottles is higher.
4. Limitations Traditional labels are bonded to the surface of the container by an adhesive that tightly bonds the label to the container. The sales of the products are not as good as expected. If you use self-adhesive labels, you will only waste some labels, you can reprint a new batch of labels, stick them on the unused bottles, and if you are not satisfied with the bottle, It is possible to change only the bottle and the label can continue to be used. In this case, if an in-mold label is used, it is likely to cause a double waste of a large number of bottles and labels. Containers made by the blow molding process must take into account the curvature of the container if an in-mold label is required. If the curvature of the container is too large, such as a round bottle, it is difficult to vent during the in-mold labeling process, then the in-mold label should not be used. In addition, the container made by blow molding is too large, and it is not suitable to use an in-mold label.
Second, the printing technology of the in-mold label
The in-mold label embeds the already printed label into the container during the blow molding or injection molding process, so that the label and the container are integrated. The basic process of in-mold labeling during the blowing process: the pre-printed in-mold labels (pre-label and back label) are stacked in a single sheet and placed in the two label boxes of the in-mold labeling machine. . As the bottle mold is opened, the front and back labels are picked up by the robot, the label printing surface is facing inward, and the solid adhesive is placed face outward on the molds on both sides. The vacuum hole on the mold firmly adsorbs the label. Inside the mold. When the raw material of the plastic bottle is heated and drooped in a hose shape, the labelled mold is quickly closed, and the air is blown into the hose so that it is in close contact with the mold wall, which is the blow molding process. At this time, the temperature in the entire mold is still relatively high, and the label-shaped adhesive adhering to the original shape of the bottle begins to melt and is combined with the plastic bottle body. Thus, when the mold is opened again, the plastic bottle body is formed, and the label is integrated with the bottle body.
1. in-mold label material selection
The film materials used in in-mold labels are divided into two major categories: paper and film. Ordinary synthetic paper has poor surface smoothness, low strength, and cannot be elastically deformed. It is not suitable for high-grade color printing, and is generally suitable for large-area barrel applications. The unique multi-layer co-extruded surface material of the film material has a smooth surface suitable for various printing methods. The label processing process does not cause overprinting and die-cutting problems due to deformation. Among them, materials such as Primax and FasClear can be stretched and contracted. The application on the plastic bottle body can be deformed according to the deformation of the bottle body, and the label wrinkle phenomenon does not appear on the surface of the bottle body. The surface of the film material does not absorb ink, so the label printed on the film material has bright color, strong stereoscopic effect, and the color effect is obviously superior to paper materials. It is suitable for high-grade color printing and is generally suitable for various delicate products. PE, PP or a combination of PE and PP.
2. Printing and processing of in-mold labels
Design the pattern on the surface of the container as an INL label. The shape of the label is determined by the contour of the container to be filmed, and the thickness of the label is between 60 and 100 μm.
1 paper feeding and tension control, the label material should use 152mm paper core tube, the large diameter paper core tube can ensure the bending deformation of the material near the paper core is small, and the deformation of the processed label is small. In addition, the printing machine is required to be equipped with an automatic material tension control device, which ensures accurate label overprinting.
2 corona treatment, when the surface tension is greater than 40 dynes, can meet the wetting of the ink, no corona treatment. However, when the surface tension is less than 40 dynes, it is necessary to corona to satisfy the firmness of the ink after printing. The negative effect of random corona treatment is to generate a large amount of static electricity on the surface, which makes the label peeling difficult when applied, so minimize random corona and reduce static electricity.
3 printing, the surface material of the in-mold label material is synthetic paper. It can be realized by various printing methods such as offset printing, convex/flexographic printing, gravure printing and screen printing. In these several printing methods, it can be subdivided according to the quantity and requirements. Offset printing has the advantages of flexible production and rich printing layers, suitable for printing small batches and varieties. The in-mold label with high printing quality is printed by convex/flexible UV ink, which makes the printing color more vivid, fast drying and high integral molding efficiency, which is suitable for medium and large batch production. The gravure ink layer is thick and scratch-resistant, and the printing speed is also the fastest. It is especially suitable for printing long-running large-volumes. Screen printing is suitable for making transparent labels that require a base color or a lot of printed solids.
a. First, determine the printing surface and the surface of the adhesive. It can be identified by the method of checking the material's dyne value or by using a solvent to wipe the surface of the film.
b. According to the proportion of film shrinkage deformation, the labeling direction of the label should be parallel to the machine direction to ensure the minimum deformation of the label. Correctly control the tension of the material to prevent the deformation of the material from excessive tension and the bending of the label in the machine direction.
c. Use suitable ink and varnish to ensure the scratch resistance of the label. Offset printing is suitable for fast drying non-skinning inks, such as POP, TSP inks, etc., using UV ink printing can achieve the best printing quality. The amount of dampening solution is reduced by 10% to 15% compared with the normal case (subject to the printing plate). Excessive dampening solution can cause pseudo-drying and ink emulsification in printing. The pH of dampening solution should be controlled between 6 and 6.5.
For embossing and flexo printing, UV ink can be used, which can be dried instantly and the ink is bright.
d. The materials of the more commonly used film-based in-mold labels are softer, and need to be stacked when labeling, which is easy to generate static electricity. In order to be able to stack the printed labels neatly, the labels can be smoothly peeled off. It is required to install static eliminators on the printing, die cutting, waste cutting, label cutting, label stacking, etc. to ensure the finished labels. No static electricity. Static electricity is related to temperature and humidity. The ideal temperature in the printing workshop is 21 °C ± 2 °C, and the relative humidity is about 50%.
4 hot stamping, in-mold label material can be bronzing process with anodized aluminum foil of general-purpose film material.
5 glazing. The in-mold label material must be glazed after printing to protect the ink and achieve a smooth surface finish. Use high-quality, scratch-resistant, special varnish that does not cause shrinkage deformation to avoid bending and deformation of the label after glazing. Flat, smooth surface labels do not stick and are easily separated when stacked. The varnish can be selected from aqueous or oily infrared varnishes and UV varnishes that match the ink.
6 die-cutting, because there is no bottom paper, the die-cutting of the in-mold label is different from the traditional die-cutting. According to the customer's specific conditions, it can be die-cut or cut after cutting. Regardless of which die cutting is used, a hardened, special steel die cutting tool must be used. The die-cutting rolls for in-line die-cutting are specially manufactured by the supplier, and are cut and then die-cut using a wine label die-cutting machine.
7 The packaging of the finished product label, the finished product label will have the problem of thickness inconsistency due to the inconsistent surface ink layer. If the labeling is unreasonable, the label bending phenomenon will occur. It is recommended to use the rigid carton packaging, or the plywood at both ends to be bundled and contracted. Film packaging to ensure the flatness of the label and to prevent damage to the edges of the label.
8 Labeling, placing the label on a robot with a special operating device through special handling equipment. The label is placed by the robot and the label is fused with the plastic to form a seamless whole.