On the anti-counterfeiting characteristics and pri

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On the anti-counterfeiting characteristics and printing technology of IML in mold label

in mold label (IML) is a special label that uses hot melt solid adhesive to bond with the surface of plastic bottle body when making bottle body, and is integrated with the bottle body in the mold. The biggest feature of plastic bottle with in mold label is that the label and the bottle body are on the same surface. It feels that there is no label, and the color pattern is as if it is directly printed on the surface of the bottle body

I. characteristics of in mold labels

1. Aesthetics traditional labels mainly include heat shrinkable labels, silk direct printing labels and adhesive labels dominated by self-adhesive labels. Direct silk printing label is to directly print the pattern and text on the container packaging through silk printing. Its overall effect is good, and the pattern and text have texture. However, due to the limitation of silk printing, it is difficult to reflect the exquisite pattern and small text. When there are many printing colors, the price of direct silk printing is more expensive. As a label, the cost of heat shrinkable film is lower than that of self-adhesive label and direct silk printing label, but the heat shrinkable label is easy to be damaged, the overall image is not very good, and it is not conducive to environmental protection; Self adhesive labels can perfectly reflect the requirements of exquisite labels, but their cost is more expensive than heat shrinkable film labels

the close combination of the label in the mold and the bottle body has the overall effect of direct silk printing, and can perfectly reflect the exquisite patterns and small words like the self-adhesive label. Because the in mold label is combined on the bottle body, it is less likely to be damaged and fall off than the self-adhesive label and heat shrinkable label, which can keep the label intact and beautiful for a long time

2. Anti counterfeiting the use of in mold labels requires a special mold, which has a high production cost and plays a cost-effective anti-counterfeiting function. At the same time, the printing process of in mold label is more difficult than that of traditional label, so as to achieve the purpose of process anti-counterfeiting

3. There are many kinds of environmentally friendly in mold label materials. Common plastic containers are matched with in mold label materials with the same composition. At the same time, because the label is combined with the container, the recycling rate of the bottle body is higher

4. Limitations traditional labels are bonded to the surface of containers through adhesives. In mold labels closely combine labels and containers. The sales of the product is not as good as expected. If self-adhesive labels are used, only some labels will be wasted. A batch of new labels can be reprinted and pasted on the unused bottle body. At the same time, if you are not satisfied with the bottle body, you can only change the bottle body, and the labels can continue to be used. In this case, if in mold labels are used, it is likely to cause a lot of double waste of bottle bodies and labels. If the containers made by blow molding process need to use in mold labels, the curvature of the containers must be considered. If the curvature of containers is too large, such as round bottles, and it is difficult to exhaust in the process of in mold labeling, in mold labels should not be used. In addition, blow molded containers are too large, and it is not suitable to use in mold labels

II. Printing technology of in mold label

in mold label is to embed the printed label into the container in the process of blow molding or injection molding, so as to integrate the label and the container. The basic process of in mold labeling during bottle blowing: stack the pre printed in mold labels (including front label and back label) in the form of a single sheet and place them in the two label boxes of the in mold labeling machine. With the opening of the bottle mold, the front and back labels are sucked up by the manipulator. The printed side of the label faces inward and the solid adhesive side faces outward and is placed in the molds on both sides. The vacuum holes on the mold firmly absorb the label in the mold. When the raw material of the plastic bottle is heated and sagged in the shape of a hose, the mold with the label is quickly closed, and air is blown into the hose to make it close to the mold wall, which is the blow molding process. At this time, the temperature in the whole mold is still relatively high, and the label solid adhesive close to the prototype of the bottle begins to melt and combine with the plastic bottle. So when the mold is opened again, the plastic bottle is formed, and the label marked at 0.01~500 mm/min is integrated with the bottle

1. Selection of in mold label materials

the film materials used in in mold labels are divided into 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. It is generally suitable for the application of large-area can bodies. The unique multi-layer coextrusion surface material of film material has a smooth surface, which is suitable for a variety of printing methods. The label processing process will not produce the problems of overprint and die cutting inaccuracy due to deformation. Among them, materials that can stretch and shrink deformation, such as primax and FasClear, can deform with the deformation of the bottle body when applied to the plastic bottle body, and the surface of the bottle body will not wrinkle the label. The surface of the film material does not absorb ink, so the smoke emitted by the film material printing is about 15.55 trillion cubic meters every year. The label has bright color, strong three-dimensional sense, and the color effect is obviously better than that of paper materials. It is suitable for high-grade color printing and generally suitable for the application of all kinds of exquisite products, mostly PE, PP or the compound of PE and PP

2. Printing and processing of in mold labels

the pattern on the surface of the container is designed as an inl label. The shape of the trademark is determined by the outline of the container to be coated, and the thickness of the label is 60-100 μ M

① for paper feeding and tension control, 152mm paper core tube should be selected as the label material. The paper core tube with large diameter can ensure that 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 can ensure the accuracy of label overprint

② corona treatment, when the surface tension is greater than 40 dyne, it can meet the wetting of ink without corona treatment. However, when the surface tension is lower than 40 dyne, corona must be used to meet the firmness of the ink after printing. The negative effect of random corona treatment is that a large amount of static electricity is generated on the surface, which makes it difficult to peel off the common optional durometers such as Brinell and Leeb when applying labels, so try to reduce random corona and the occurrence of static electricity

③ printing, the surface material of in mold label material belongs to synthetic paper. It can be achieved by offset printing, embossing/flexographic printing, gravure printing and other printing methods. Among these printing methods, it can be subdivided according to the printing volume and requirements. Offset printing has the advantages of flexible production and rich printing levels, which is suitable for printing small batches and multiple varieties. In mold labels with high printing quality requirements are printed with convex/flexible UV ink, which makes the printing color more colorful, drying faster, and has high integration efficiency. It is suitable for medium and large batch production. The ink layer of gravure printing is thick and scratch resistant, and the printing speed is also the fastest, which is especially suitable for printing large quantities of long edition; Silk printing is suitable for making transparent labels that require background color or more on-the-spot printing

a. first, determine the printing surface and adhesive surface, which can be identified by checking the dyne value of the material, or by wiping the film surface with solvent

b. According to the proportion of film shrinkage deformation, the label arrangement direction should be parallel to the machine direction to ensure the minimum deformation of the label. Correctly control the tension of the material to avoid excessive tension, material deformation and the bending of the label in the direction of the machine

c. Select appropriate ink and varnish to ensure the scratch resistance of the label. Offset printing is suitable for quick drying non skinning inks, such as pop and TSP inks. UV ink printing can achieve the best printing quality. The amount of fountain solution is reduced by 10% - 15% compared with the general situation (subject to the printing plate not drying). Too much fountain solution will lead to false drying and ink emulsification in printing. The pH value of fountain solution should be controlled between 6 and 6.5

UV ink can be used for embossing and flexo printing, so that it can be instantly dry and the ink color is bright

d, the commonly used film in mold labels are made of soft materials, which need to be stacked when labeling, and are easy to generate static electricity. In order to stack the printed labels neatly and peel them off smoothly during labeling, it is required to install Static Eliminators on the printing, die cutting, waste discharge, label cutting, label stacking and other stations of the printing machine to ensure that the finished labels are free of static electricity. Static electricity is related to temperature and humidity. The ideal temperature of the printing workshop is 21 ℃± 2 ℃ and the relative humidity is about 50%

④ hot stamping, the in mold label material can be used as the Standard Specification for the hot stamping process test of electrochemical aluminum foil of general film material

⑤ glazing. In mold label materials must be polished after printing to protect the ink and achieve the purpose of smooth label surface. Use a high-quality, scratch resistant Special polish that will not shrink and deform to avoid bending and deformation after polishing the label. Labels with flat and smooth surfaces will not adhere and are easy to separate when stacked. Gloss can choose water-based or oily infrared gloss and UV gloss that match the ink

⑥ die cutting. Because there is no backing paper, the die cutting of in mold labels is different from the traditional die cutting of non glue labels. According to the specific situation of customers, online die cutting or die cutting after sheet cutting can be carried out. No matter what kind of die-cutting is used, special steel die-cutting tools that have been hardened must be used. The die-cutting roller of online die-cutting is specially manufactured by the supplier, and the wine label die-cutting machine is used for die-cutting after sheet cutting

⑦ for the packaging of finished labels, the thickness of finished labels will be inconsistent due to the inconsistent ink layer on the surface. If the binding is unreasonable, the labels will be bent. It is recommended to use hard paper boxes for packaging, or place plywood at both ends for binding, and use shrink film for packaging, so as to ensure the flatness of the labels and prevent the edges of the labels from being damaged

⑧ labeling: place the label on the robot with special operation device through special processing equipment. The robot places the label and fuses the label with the plastic to form a seamless whole


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