Bottle shape and shrinking process

Bottle shape and shrinking process Release time: 2020-11-23 In recent years, due to the characteristics of heat-shrinkable labels, such as body wrapping, bright printing patterns, and suitable for mass production, they have been increasingly used by various products, especially It is PVC labels that are favored by major beverage manufacturers. However, due to the large differences in the shrinkage equipment and processes used by the manufacturers, the shrinkage effect is different. Here, I will focus on the special-shaped bottles. Comparison of several shrinkage processes The main shrinkage processes currently used are: water bath method, electric heating method and steam method. From a practical point of view, both in terms of shrinkage effect and production efficiency, the superiority of the steam process is reflected At least the following points should be paid attention to the shrinkage of special-shaped bottles: 　　1. The bottle type with a small upper part and a large lower part. This bottle type is mostly used in peanut butter, milk, juice and other food industries, such as Shanghai Danone Weishuang cheese drink bottle, Mengniu Large-grain fruit bottles, Xuzhou Tianshan snow ice milk bottles, Beijing Huabang Juice Vinegar Bottles, etc. The best solution for this type of bottle type is the use of steam technology when performing trademark heat shrinkage. First shrink the bottom, and make the shrinkage stress reach the maximum value, to prevent the upward vector stress generated during the upper shrinkage, the trademark will move upward, causing the defect that the trademark on the lower part of the bottle is not covered; if Electric heating technology is used, because its heat source is not positional, so it cannot be operated according to the aforementioned process method of first shrinking the lower part, which means that more bottles will inevitably leak out from the lower part. If you want to improve under this process condition, you can start from improving the curvature of the lower part of the bottle body, and make the original gradual arc surface smaller, thereby forming an obvious step to lock the lower part of the label. It is also an auxiliary method to improve the label's longitudinal shrinkage, but it is not as effective as the previous improvement method.　　2. Bottle type with large upper part and small lower part　　 This bottle type is mostly used in industries such as cup-style instant noodles and ice cream. For example, ice cream packaging boxes such as Heluxue and Nestlé. This type of cup has the characteristics of a smoother surface and no protrusions. Generally, the empty packaging electric heating process is used to shrink the trademark. Since the position of the heat source cannot be adjusted, the shrinking process is performed at the upper and lower parts at the same time. At this time, the label will move downward due to the vector stress generated during the shrinking process. By changing the shape of the part of the cup (for example, we can add a circle of protrusions at the upper end to fix the upper end of the label), this phenomenon can be fundamentally eliminated, and some manufacturers adopt the form of applying glue on the upper end of the label back. Solved, but not as effective as the previous solution. 3. The bottle type with two large ends and small middle bottle is mostly used in milk, beverage and other industries, such as Shanghai Danone high-calcium extra-rich milk bottle, Mengniu sour milk bottle, Beijing Prince Milk lactic acid bacteria milk bottle, etc. This type of bottle type is generally used The steam process is difficult to control if the electric heating process is used, and it is difficult to avoid the label moving to the middle. When using steam, it is necessary to follow the order of bottom-middle-up to shrink. If the surface of the bottle body does not have longitudinal stripes but is smooth, in order to prevent air from accumulating in the middle of the label and not dissipating, a number of vents should be punched on the label surface.　　4. A bottle shape with a small end and a large middle. 　　 This bottle type is also used in the beverage industry, such as Watsons water bottles. This type of bottle type generally adopts the steam process, and shrinks in the order of middle-down-up to ensure the accuracy of the label position.　　 In addition to the precautions in the shrinking process mentioned above, the following issues should be paid attention to in the label design of special-shaped bottles, the production of product shrinkage, and the acceptance of user acceptance. 1. For the label of the special-shaped bottle, the pattern deformation must be taken into consideration when designing. We call it the pre-deformation design link, which means that the 3DMAX software is used in the computer to perform three-dimensional simulation and contraction of the manuscript, so that the customer can confirm the simulation. As a result, the printed pattern before shrinkage is reversed, so that the label pattern design scheme is perfect and reasonable. Since the longitudinal shrinkage of the substrate used for printing will be different (generally there is a 2-3% error), the longitudinal position of the pattern of the label after shrinkage will also be different, resulting in slight deformation and displacement (generally (About 0.5-2mm); for the horizontal direction, if the steam process is used, the deformation amplitude is small (usually about 0.5-1mm), if the electric heating process is used, the heat distribution inside the drying tunnel is uneven The congenital deficiencies of the label lead to unstable heat during the label shrinkage process. The lateral deformation of the pattern caused by the shrinkage of the same product bottle and trademark is large (the deformation value is generally about 1 to 5mm), there is no regularity, and it is difficult to control.　　2. With the changes in people's aesthetic viewpoints on products, most of the approved bottles have a special-shaped smooth surface, and they are mostly made of HDPE. After shrinking, the label will rotate relative to the bottle body. This is caused by the difference between the shrinkage rate of the HDPE bottle body and the label shrinkage rate. When heated, the label wraps the bottle body tightly and cannot rotate. Wait until it is cooled to room temperature. Later, due to the shrinkage of the bottle itself, the size is reduced, but the label basically does not shrink, so rotation occurs. For general non-frozen foods, we can use glue on the back of the label to solve the problem. For frozen, low-temperature products such as yogurt products, if glue is used, tiny wrinkles will occur in the frozen and low-temperature environment. ,Affect the appearance. Previous: Design instructions for heat shrinkable film sleeve labels