On the adhesive force of labels

Talking about: the adhesive force of labels

there is a beer label always stuck in my memory. On a business trip to Xinjiang many years ago, Wuhan took off, passed Xi'an, Lanzhou and Jiuquan, and arrived in Urumqi at 6:00 p.m. Taking advantage of the time zone difference, I still had time to visit Wusu Beer and recommend gravure metal effect label (MEC), a new printing process with metal texture, economy and environmental protection. When having dinner in the hotel, I decided to treat myself to a bottle of frozen Wusu Beer. The long green glass is matched with aluminum plated paper labels of the same color. The Wusu Beer looks like green hops at the foot of Tianshan Mountain. Out of habit, I gently stroked the abdominal label with small drops of water with my hand, and found that the label slid up and down along the bottle. It turned out that the label had lost its bonding force. I reported this label to the purchasing manager in time. It was analyzed that the aluminum coating may block the breathing of the label, and the water must not volatilize, resulting in poor adhesion. The label is particularly easy to fall off in ice water environment. Soon, we were allowed to try the MEC label on Wusu Beer, and the off label was solved

labels represent brands. Off label is a major defect in beer packaging. I was lucky to catch a business opportunity. But later, when I quoted this case in other customer factories, I met the challenge of on-site technicians, because they were more worried about the washability of labels when recycling bottles, and the packaging efficiency and cleaning cost were included in the bottle sticking scheme. It can be seen that the labeling process is not simple. The label is only the surface, and viscose is its core

wetglue

the back of the label is attached to the surface of the container, and this action is completed on the labeling machine

cutstack labels are labeled with wetglue. First, glue is applied to the surface of the rubber roller by the glue pump and transferred to the standard plate. When the standard plate rolls, it is removed from the standard box. This requires different fixtures to be designed according to different experimental forces and the shape and size of the sample. The label plate with the label continues to move forward. The opening and closing of the label cylinder refers to clamping the side edge of the label to remove the label, and then turn to the container turntable to quickly and accurately press it onto the surface of the container. The labeled container rotates with the receiving table and is brushed flat and fixed

the substrates of wet adhesive labels include aluminum foil, paper and film, which are printed by gravure, offset, flexo and hybrid printing processes respectively. Embossing and pinhole processes are also common for aesthetic or labeling needs

aluminum foil labels are widely used in the labeling of beer and wine bottles. The processed thin foil labels have good bonding performance. Compared with paper, aluminum foil has no consideration of the direction of silk flow, but the overall size, punching quality and embossing depth are closely related to affect the labeling efficiency. If the size deviation is too large, it will hinder the high-speed labeling, and the labels will either get stuck in the label box or fall out from the front of the label box; Poor punching quality will make the label overlap and adhesion, resulting in difficulty or failure of label retrieval

paper is an active material. The paper label is particularly sensitive to the temperature and humidity of the labeling environment and adopts microcomputer closed-loop control. Holding the label flat can reduce flying labels, waste labels and glue overflow. When labeling, too high or too low water absorption on the back will cause insufficient glue or too much glue, resulting in label slippage, falling off or glue waste. The technical indicators for measuring the running capacity of paper labels include: wet tensile strength, tearing degree, curl degree, (reactivity with water), back water absorption, washing time and alkali resistance

the wet adhesive label of film material has the absolute advantage of the above technical indicators, and can be used with the traditional paper label labeling machine. In the past, the biggest obstacle was that the water content of the label adhesive could not volatilize under the tight plastic, and bubbles and folds formed on the surface of the container after labeling. The gluing surface of the new OPP film had paper surface properties. Using water-based adhesive, the glue consumption was 50% of that of the paper label, and the adhesion and adhesion were the same as that of the paper label

casein glue is a water-based glue made of milk casein and other natural raw materials, with a solid content of about%, non-toxic, tasteless, odorless, biodegradable, high initial viscosity, fast curing speed, strong shear force, good ice water resistance and moisture resistance, especially suitable for high-speed labeling of beer, wine and dairy products in condensing environment. Casein gum shares milk resources with food, and its weakness is that its price fluctuates and remains high

starch glue from potatoes, wheat and corn is another natural adhesive, which has the characteristics of relatively low initial viscosity, temperature resistance, green and environmental protection, and is especially suitable for labeling hot filling containers such as tea, fruit juice and mineral water

the solid content of synthetic glue produced by mixing casein and resin is about%, which is slightly heated when used. It is suitable for PE, pet, PP and PS plastic containers and the surface of polished metal containers. Recyclable PET bottles use synthetic glue, which has the advantages of good viscosity and removal

the ingredients of hot melt adhesive include thermoplastic raw materials, wax and resin, which melt at the processing temperature of ℃, and have good initial viscosity and fast viscosity. Hot melt adhesive labeling is mostly used on containers with irregular shapes such as barrel and polygon

non drying sheet adhesive (PSL)

beverages (alcohol, soft drinks), food, medical and health products, personal care products are the traditional markets of wet adhesive labels, but self-adhesive is rapidly penetrating into the high-end market, such as beer crystal labels, which give consumers a label free vision

self adhesive, nicknamed pressure sensitive reel label (PSL), pre coated glue automatically adheres to the surface of the container under pressure. When the sensor device of the labeling machine sends out the labeling instruction, the driving wheel drives the drum label to move forward. When the self-adhesive backing paper clings to the stripping plate and changes the direction, the front end of the label is passively disengaged due to its own stiffness and is ready for labeling. At this time, the container moves on the conveyor belt, and the labeling wheel makes the label stick to the surface of the container quickly and synchronously. After labeling, the sensor sends out the operation stop command, the drive wheel is stationary, and a labeling cycle is completed

self adhesive labels are widely used in automotive, electronic, chemical and other fields, as well as variable information and anti-counterfeiting functions. Polyethylene (PE) and polypropylene (PP) films account for 60% and paper accounts for 40%. The self-adhesive label has a very flexible printing method. Embossing, soft gravure printing and silk screen printing gradually open the oil return valve brush, which is suitable for batch printing; Heat sensitive, heat transfer, laser/inkjet, and even needle printing are used for small volume printing

the technical indicators for measuring the running ability of self-adhesive include surface material, release force, backing paper, initial viscosity, final viscosity and shear strength. The adhesive of self-adhesive label is the medium between label material and bonding substrate, which plays a connecting role. According to the characteristics, adhesives can be divided into permanent and removable. Therefore, there are many different formulations to apply to different surface materials and use environments. Adhesive is the core of self-adhesive label. The main technical indicators include UV resistance, solvent resistance, cold flow ability, minimum labeling temperature and application temperature range

different from water-based adhesive, self-adhesive is mainly chemical adhesive, with great differences in adhesive properties. The following application common sense should be grasped in the labeling process:

permanence and removability: permanence is generally applied to mechanical and electrical products, and removability is generally applied to food, beverage, personal care, etc., so that containers can be recycled

container surface: self adhesive labels may be labeled on the surface of various materials, such as glass, metal, cardboard, plastic, etc. if it is a plastic surface, glue and standard materials with the same or similar chemical composition should be selected

surface structure of label substrate: intuitively speaking, rough label surface requires glue with strong viscosity

surface shape of label base material: the surface of label base material can be divided into plane and curved surface. If the label surface has a certain radian, the surface of drug bottles with a diameter of less than 3 cm may need glue with good adaptability or strong viscosity

label surface cleanliness: self-adhesive materials are most suitable for label substrates with clean, dry surfaces and no oil and dust