In-mold labels are mostly used for trademarks and label instructions on food packaging, and play an important role in food logistics, anti-counterfeiting, and identification. In-mold labeling is a new technology with great potential in China. Its promotion replaces the labeling machine, reduces the production cost of the manufacturer, and at the same time increases the recycling rate of food packaging (containers), reduces food inventory, shortens the It shortens the production cycle and improves production efficiency, and is very popular among people in the food and packaging industry. In-mold label manufacturing process The principle of making in-mold labels is to put printed paper, composite or thin labels with special hot melt adhesive on the back, and place them inside the mold before plastic blowing, injection molding or thermoforming. to produce plastic bottles or basins. Essentials for making in-mold labels: First, place the label on the inner wall of the mold; then, insert the suction plastic tube into the inner wall of the mold that wraps the label until the mold is completely closed, allowing air to fill the entire space in the closed mold; finally, the heated plastic It rapidly expands and presses against the inner wall of the mold, fixing the label on the bottle, and the completed bottle comes out of the mold. When choosing in-mold label materials, pay attention to size. Ordinary label synthetic paper has poor surface smoothness, relatively low strength and small elastic deformation. It is difficult to print high-grade colors and is suitable for large-area applications such as barrels. Paper labels are easily deformed when exposed to water or moisture and reduce their use value. However, they are less affected by static electricity during use, and the loss when blowing the bottle to absorb the label is relatively small. Paper labels and plastic bottles are not of the same material, which is not conducive to bottle recycling. The film material is a special multi-layered extruded surface material with a smooth surface that can be printed in a variety of printing methods. Deformation during label processing will not cause overprinting or die-cutting problems. Some film materials can stretch, shrink and deform. When applied to bottles, they can deform according to the shape of the bottle. After being compounded to the surface of the bottle, there will be no wrinkling of the label because the oil will not penetrate into the film under the surface of the film material. Labels printed with these materials have brighter colors and better color effects than paper-based materials. Nowadays, plastic film-based in-mold label materials are generally used at home and abroad. In-mold labels require good printability so that the powder in the oil can be firmly attached to the surface of the material. They must have good processing suitability during post-processing and are suitable for die-cutting and cold foil stamping. The in-mold label material also needs to have good usage characteristics and be able to be integrated with the plastic bottle during blow molding. The in-mold label material structure consists of a printing surface, an intermediate layer and an adhesive layer. The function of the printing surface is to accept the oil and form colorful graphics and text: the middle layer supports the printing surface, giving the material sufficient stiffness and transparency, and does not deform under the influence of the printing press and high temperature, ensuring accurate overprinting. The adhesive layer melts under the action of temperature, making the label material and the plastic container integrated to ensure that the label and the plastic bottle are firmly adhered together. There are two structures on the surface of the adhesive layer: flat non-reticulated structure and reticulated structure. The ones without mesh structure are in direct contact with the blank during use and naturally exhaust, which is suitable for small-area labels. The reticulated structure refers to an adhesive layer with a reticulated structure embossed on the surface of the adhesive layer. During labeling, the gas between the label and the bottle is exhausted through the reticulated exhaust channels. The generation of bubbles is reduced, and the glue layer also has antistatic properties. To prevent double sheets from appearing during printing; the adhesive layer should also have certain sliding properties to ensure smooth separation of labels and enable smooth printing processing. The specific method of making in-mold labels: Taking PP bottles as an example, the labels are also made of PP synthetic paper. After surface treatment and printing of the trademark, a special hot-melt adhesive is coated on the back and die-cut to make the label. In-mold labels are divided into front labels and back labels depending on the location on which they are attached, that is, the trademark is affixed to the front or back of the package. The printed labels are stacked in single sheets, and the front label and back label are placed in two boxes of the in-mold labeling machine. At the beginning of a cycle of the mold, the bottle mold is opened, and the printed front and back labels are picked up by a robot and placed on the corresponding positions in the mold. The label printing face faces the inner wall of the mold, and the small holes in the mold absorb air and use vacuum to firmly adsorb the label into the mold. At the same time, the raw material of the plastic bottle is heated and droops like a hose, and the mold with the label adsorbed on the inner wall quickly closes. Air is blown into the hose so that the plastic bottle clings to the inner wall of the mold. At this time, the temperature in the entire mold is quite high. When the back of the label is close to the bottle, the solid adhesive coated on the back of the label begins to melt, and the label and the plastic bottle are combined together in the mold. When the mold is opened, the plastic bottle is formed, the label and the bottle are integrated into one, and the printed trademark is embedded on the surface of the plastic product.

In this example, the label and bottle are on the same surface, as if there is no label attached, and the color graphics and text appear to be printed directly on the surface of the bottle. The extraction method of in-mold labeling cannot be ignored. After the labels are die-cut, a robot is used to suck them one by one into the mold cavity. The temperature of the extruded plastic and the pressure of the inhaled air are used to fuse the labels and plastic bottles into one. Nowadays, there are two methods for in-chess labeling: vacuum negative pressure mold suction method and electrostatic mold suction method. Vacuum mold suction method is a relatively common method. Add a few holes for vacuuming on the original mold. No special casting equipment is required, the cost is low, the use effect is very good, and the vacuum mark is not easy to detect. This technology is now very mature; the electrostatic mold suction method can also achieve in-mold adsorption labels. The advantage is that there is no need to modify the original blow molding equipment. but. This type of equipment has not yet been seen in the country. Advantages of the in-mold label: The appearance is novel and beautiful. The in-mold label is formed together with the plastic container. The in-mold label and the bottle body naturally touch together and are firmly embedded. The label changes with the shape of the powder bottle body, and the label cannot be seen on the plastic bottle. /p>