Sino IML has been developed in Europe, the United States and other counties for more than 20 years, and has been applied in industries such as oil, daily necessities, food and medicine.
What is Sino IML? It refers to PP or PE synthetic paper in the surface treatment, coated with a special hot melt adhesive processing into the back of the special label paper, printed into a trademark. The machine hand is used to suck up the printed label and place it in the mold. The vacuum hole on the mold firmly adsorbs the label in the mold. When the plastic bottle’s raw material is heated and drooped into a flexible tube, the mold with the label is quickly closed, and the air is blown into the tube to make it close to the mold wall, then the temperature in the whole mold is still relatively high, the label solid adhesive next to the prototype bottle body begins to melt and bond to the plastic bottle body in the mold. When the mold is opened again, the plastic bottle body is formed, and the label and the bottle body are fused into one. Make the beautifully printed logo firmly embedded in the plastic products, labels and plastic bottles on the same surface, feel no label, color graphics as directly printed on the surface of the bottle.
This article will introduce in-mold labeling technology involved in the main technology.
Ⅰ. Materials
Sino IML label technology content is very high, the first is reflected in the material. The first to enter the Chinese market is Japan’s Yupo in-mold label, known as the world’s most successful in-mold label materials. Now, Polyart (Pria) blow molding internal standards are also entering the Chinese market, and some local companies are also stepping up research and development of this material.
Sino IML should first have good printability, to ensure ink is firmly attached to the surface, in the post-processing process to ensure good processing adaptabilities, such as die-cutting and cold stamping processing adaptability. Next, this kind of material must satisfy the user characteristic, when blow molding and the plastic bottle unifies.
Sino IML materials are divided into paper and plastic film. The former deforms when exposed to water or moisture and reduces its use-value. However, the advantages of the former are that there is no electrostatic interference and the label can be absorbed during bottle blowing. In addition, the former is not the same material as the plastic bottle and is not easy to be recycled. Now, the domestic and foreign general use of plastic film in-mold label materials.
The Sino IML material structure is composed of a printing surface, an intermediate layer and an adhesive layer. The role of the printing surface is to accept ink, the formation of color graphics and text; the middle layer to support the printing surface, to give the material enough stiffness and transparency, in the press and high temperature under the action of deformation, to ensure accurate overprinting. The adhesive layer will melt under the action of high temperature, making the label material and the plastic container become an integral whole, ensuring that the label and the plastic bottle firmly stick together.
Printed surface materials generally have three: PE, Bopp and PE + PP. Since most plastic containers are currently made of PE material, the use of PE in-mold labels is more conducive to recycling, as they are homogeneous materials. In the production of in-mold labels, in order to improve the ink-affinity printing surface materials, generally need to coat surface coating or corona discharge method to improve the surface energy.
There are two kinds of structures on the surface of the adhesive layer: planar meshfree structure and reticulated structure. The former is used in direct contact with the blank, natural exhaust, suitable for small area labels. The latter imprints the reticulated structure on the surface, and when in use, the gas is vented through the reticulated exhaust passage, thus avoiding the production of air bubbles. The adhesive layer also has the antistatic property to prevent double sheets when printing; in addition, it also has the sliding property to ensure the smooth separation of labels, making the printing process smoothly.
Ⅱ Sino IML label printing
Different printing factories can choose different printing processes according to their own equipment conditions. Offset printing, Flexo Printing, relief printing and gravure printing can be printed in-mold labels, to offset and flexo printing.
1. Offset printing
Offsctdruckereien in the fine dot printing advantages are very prominent, but lines, field printing effect and printing saturation than other printing methods. Offsctdruckereien as flexo printing (Inline) printing processing, so printing must be Offline (Offline) die-cutting, cold stamping, glazing and other processes. But offsctdruckereien suitable for small batch label printing, short cycle, strong flexibility.
2. Gravure printing
Field printing and printing color saturation is superior to offset printing, not suitable for printing small dots and rich layers of trademarks. But the chromatic aberration control is more convenient. In gravure press, in-mold label material than another printing path to the paper, so there is a greater chance of static electricity. Gravure printing plate high cost, long cycle, so suitable for the long version of in-mold label printing.
3. embossing
Letterpress is suitable for printing on-site and line trademarks, printing small dot effect is not ideal, the same batch of products are easier to control the color difference, but there will be ink. From the cost point of view, then gravure printing and flexo printing are cheaper.
4. Flexography
The outstanding advantage of Flexography is that the printing and finishing processes can be carried out in one go, with the front end being the feed end and the back end being the final printed finished product, enabling the linking of the printing and finishing processes. Now, with the improvement of flexographic plate-making technology, the quality of dot printing has made great progress. The adoption of flexographic printing for in-mold labels has been approved by some manufacturers, but the use of environmentally friendly water-based ink printing is still immature, at present, experienced manufacturers are using a good flow of UV Ink, and in-mold label printing trend.
Ⅲ Post-processing of Sino IML
In-mold label printing, according to customer requirements also need to glaze, bronzing and die-cutting and other post-processing.
1. Polish
In order to improve in-mold label gloss and product surface decoration characteristics, and in order to improve in-mold label and high-temperature resistance, printing in-mold label can be glazed. In labeling, if the use of vacuum adsorption in-mold label, should be appropriate to add antistatic agent and adjust the smoothness of light oil; if the use of electrostatic adsorption in-mold label, on the oil should not add antistatic agent; If the in-mold label printing also need stamping should be used for bronzing UV varnish; if the Polish added additives, before glazing should be tested to avoid the whole batch of products scrapped.
2. Gilding
In-mold label material above hot stamping can be used first after the oil, or first after the oil after hot stamping different stamping process. Hot stamping can be used as cold and hot stamping two technologies. Cold stamping is mainly used for Flexography, the use of cold stamping to obtain a better visual effect requires a higher technology, we recommend the general first cold stamping after the printing process, this can use a thick layer of ink to cover the edge of cold stamping burr. If the customer can accept the visual effect of cold ironing, this technique is recommended.
For in-mold label hot stamping, factors include anodized, stamping temperature, stamping pressure and stamping speed. Hot, Hot Sol should be used in hot sol melting point is lower than the hot sol melting point of gold foil, and strictly control hot stamping pressure and time, to avoid in-mold label material concave-convex deformation. Hot stamping, first in-mold label material characteristics and anodized stamping suitability as the premise, adjust the size of the stamping plate and stamping speed to determine stamping temperature and stamping pressure, first adjust the pressure, and then determine stamping temperature. Overall, stamping can improve in-mold label added value.
3. Die-cutting
In-mold label die-cutting and poker die-cutting mode are very similar to cut-off die-cutting. Because die-cutting is the last processing process of the in-mold label, die-cutting, when the electrostatic removal is very important, because the electrostatic removal is not ideal, will lead to stack is not tidy, resulting in labeling location and double-sheet problems.
In-mold label die-cutting is divided into sheet-fed die-cutting and web die-cutting two ways, which specific way, according to the manufacturer’s equipment and in-mold label material type. In this two die-cutting, web die-cutting is divided into line die-cutting (Inline Diecut) and Offline DIECUT.
Web flat die-cutting mode applicable to the web in-die label materials, this is an off-line die-cutting mode, die-cutting precision is very high. It has two ways of feeding paper, one is intermittent feeding paper, the die-cutting device is only up and down movement; the other way is continuous feeding paper, die-cutting device not only up and down movement, but also back and forth swing. Two ways of working after the label die-cutting conveyor to the stacking station.
Drum paper rotary die-cutting is applicable to the drum die label, die-cutting in two ways: online die-cutting and off-line die-cutting. Rotary die-cutting is the most perfect die-cutting way, its die-cutting precision is very high, but the production cost of the die-cutting roll is high, suitable for more than 100,000 sets of the long versions of the inside label. This die-cutting method is used in Flexography production, is high efficiency, more popular in the United States.
Sheet-fed flat die-cutting suitable for sheet-fed die-cutting label material, this is an off-line die-cutting method, processing accuracy in general, by the automatic paper feeder, die-cutting Automatic Waste Row, the finished product label is placed on the stacking station by the manipulator.
Ⅳ The way of Sino IML
Die-cutting into the label, the use of a manipulator piece by piece into the cavity, the use of extrusion plastic temperature and suction air pressure, the label and plastic bottles melt into one. Now, Sino IML has two ways: vacuum suction mode and electrostatic mode.
The vacuum mode is the most common and widely used method at present. Plastic packaging products companies can add in the original mold vacuum micro-hole, no special equipment, low-cost, very good use effect, and not easy to detect the vacuum mark, the technology is now very mature.
The most advantage of this technology is that it does not need to reform the original blow molding equipment, but at present, there is no successful case in our country. The electrostatic model has special requirements for Sino IML technology, equipment and physical properties of labels:
1) a high voltage electrostatic discharge (ESD) system must be added to the device to uniformly apply sufficient electrostatic charge to the label for a short period of time and attach the label to the blow molding cavity at zero potential through a robotic arm.
2) the electrostatic elimination system must be added to the equipment to eliminate the residual static electricity after each labeling and to avoid its influence on the electric control system of the Sino IML machine and the phenomenon of label adhesion caused by static electricity.
3) the appropriate label substrate and printing ink must be used.
Ⅴ Advantages of Sino IML
1. Beautiful appearance
The Sino IML is formed with the plastic container. No corner of the label can be seen on the plastic bottle body. It looks very beautiful. Secondly, because the Sino IML printing effect is good, suitable for printing details and screen fine manuscript, so strong visual performance. Because the Sino IML does not have a corner, it will not be like self-adhesive as “missing” နှင့် “missing” phenomenon. In a humid environment, Sino IML will not bulge, also will not be moldy.
2. Security
At present, only a few companies in China offer Sino IML services, because of the large investment in one-off equipment. In mold design, label printing and processing, the labeling forming process contains many factors, so there are technical barriers to Sino IML, to forge, counterfeit trademarks is not an easy task. Now, very popular self-adhesive label because the technology is very mature, counterfeiting is easy, and low cost, so fake products prevail, damaging the interests of manufacturers. The use of Sino IML, so that the manufacturers to eat anti-false certainty, finally can breathe a sigh of relief.
3. Recycle
The Sino IML material and the plastic bottle belong to the same material, after the consumer uses the product, the plastic bottle can be crushed together to recover, the recovery efficiency is high, the cost is low, belongs to the green environmental protection packing material. If it is a self-adhesive label, recycling more trouble, need to tear off the self-adhesive label, the bottle of adhesive removal, recycling, low efficiency, and recovery costs. Therefore, Sino IML are in line with the development trend of green packaging.
Ⅵ Application of Sino IML
From the domestic and international development, Sino IML is mainly used in the following industries:
1. Oil Industry: including lubricants, gear oil, antifreeze products such as plastic container packaging.
2. Daily chemical industry: Shower Gel, shampoo, detergent, detergent and personal care products and another product packaging.
3. Food industry: soy sauce, ice cream, coffee, fruit juice, tea drinks, yogurt, and other products packaging.
4. Pharmaceutical industry: High-End drug packaging
In Europe and the United States, Sino IML development began to enter the track of stable development; in China, Sino IML is 70% of the speed of high-speed development. Looking forward to the future, the Sino IML will be a strong challenge to self-adhesive labels and will eliminate the paper-based Sino IML, completely to the plastic material label direction. Furthermore, more and more end customers will use Sino IML.
