The hottest perspective in mold label technology I

2022-08-08
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Perspective in mold label technology (I)

in mold label has a history of more than 20 years in developed countries in Europe and the United States. In recent years, this new label technology has taken root in China, and has been applied in oil, daily necessities, food, medicine and other industries. What is in mold label? It refers to the special label paper processed with PP or PE synthetic paper on the surface and coated with special hot-melt adhesive on the back, which is printed and made into a trademark. Use the manipulator to suck up the printed label and place it in the mold, and the vacuum hole on the mold will 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 the air is blown into the hose to make it close to the mold wall. 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 in the mold. So when the mold is opened again, the plastic bottle is formed, and the label and the bottle are integrated. The beautifully printed trademark is firmly embedded and operated. The multi task operating system developed by our company is embedded on the surface of plastic products. The label and the plastic bottle are on the same surface. It feels that there is no label, and color graphics and texts are directly printed on the surface of the bottle. This kind of packaging effect without label feeling is being favored by consumers. This paper will introduce the main technologies involved in in mold label technology. I The technical content of in mold labels of materials is very high, and the first thing to reflect is materials. The first one to enter the Chinese market is Japan Yupo in mold label, which is known as the most successful in mold label material in the world. Now, the internal standard of French Polyart blow molding mold has also entered the Chinese market, and some local enterprises are also stepping up the research and development of this material. In mold labels must first have good printability to ensure that the ink is firmly attached to the surface. In the post-processing process, good processability should be ensured, such as die cutting and cold stamping. Secondly, this material should meet the use characteristics and be integrated with the plastic bottle during blow molding. In mold label materials are divided into two categories: paper and plastic film. The former will deform in case of water or moisture, reducing its use value, but its advantage is that there is no electrostatic interference, reducing the loss of absorbing labels when blowing bottles. In addition, it is not the same material as plastic bottles, which is not convenient for recycling. Now, plastic film in mold label materials are generally used at home and abroad. In mold label material structure is composed of printing surface, intermediate layer and adhesive layer. The function of printing surface is to receive ink and form color pictures and texts; The middle layer supports the printing surface, gives the material enough stiffness and transparency, does not deform on the printing machine and under the action of high temperature, and ensures the accuracy of overprint. The adhesive layer will melt under the action of high temperature, so that the label material and the plastic container become one, ensuring that the label and the plastic bottle are firmly adhered together. There are generally three kinds of printing surface materials: PE, BOPP and PE +pp. At present, most plastic containers are made of PE, so the use of PE in mold labels is more conducive to recycling, because they are homogeneous materials. In the production of in mold labels, in order to improve the ink affinity of printing surface materials, it is generally necessary to coat the surface coating or improve the surface energy by corona discharge. There are two kinds of structures on the surface of the adhesive layer: flat non striated structure and striated structure. The former is in direct contact with the blank when in use, natural exhaust, suitable for small area labels. The latter is embossed with a grain structure on the surface. When in use, the gas exhausts through the exhaust channel of the grain, avoiding the production of bubbles. The adhesive layer also has antistatic property to prevent double sheets during printing; In addition, it also has sliding property, which ensures the smooth separation of labels and the smooth printing process. II In mold label printing different printing manufacturers can choose different printing processes according to their own equipment conditions. Offset printing, flexo printing, embossing and gravure printing can print in mold labels. At present, offset printing and flexo printing are in the majority. 1. Offset offset printing has outstanding advantages in fine dot printing, but the line, field printing effect and printing saturation are not as good as other printing methods. Offset printing cannot realize inline printing processing like flexo printing, so offline die cutting, cold pressing, polishing and other processes must be carried out after printing. However, offset printing is suitable for small batch label printing, with short cycle and strong flexibility. 2. Gravure field printing and printing color saturation is better than offset printing, and it is not suitable for printing small dots and trademarks with rich layers. But color difference control is more convenient. On gravure printing machines, the paper path of label materials in the mold is longer than that of other printing methods, so the chance of static electricity is greater. Gravure plate making has high cost and long cycle, so it is suitable for long plate in mold label printing. 3. Embossing embossing is suitable for printing field and line trademarks. The effect of printing small dots is not ideal. It is also easier to control the color difference of the same batch of products, but ink bars will appear. In terms of cost, it is cheaper than gravure printing and flexo printing. 4. Flexographic printing the outstanding advantage of flexographic printing is that the printing and post-processing processes can be completed at one go. The front end is the feed end, and the rear end obtains the final printing and processing finished products, realizing the online production of printing and post-processing. Now, with the improvement of flexographic plate making technology, the dot printing quality has made great progress. Flexographic printing of in mold labels has been recognized by some manufacturers, but printing with environmental friendly water-based ink is not mature. At present, experienced manufacturers use UV ink with good fluidity, which has become the trend of in mold label printing

the lines and printing molding of Jinmin PLA material production are shown in Figure 3. This article comes from the copyright of the network and belongs to the original author of the experimental method of concrete small hollow blocks gb/t 4111 ⑴ 997. It is only for the determination of the applicability of the tension machine fixture. It is difficult for everyone to share and learn. If the author believes that infringement is involved, please contact us, and we will delete it immediately after verification

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