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Performance and appearance requirements for the sealing technology of beverage container lid

in recent years, with the continuous development of new beverage containers (such as various bottles, barrels, cans) packaging, container lids are also innovating. Of course, although there are many types of container covers, their functions are to ensure the sealing of containers, and they should also have good opening performance and novel appearance design

the function of the container cover


the function of the cover is to ensure the sealing of the container, protect the contents of the container and prevent it from deterioration during the storage period. Therefore, all kinds of covers must first have air tightness and tightness to ensure that the contents do not contact the external environment and do not leak; For carbonated beverages and other inflatable beverages, the air tightness requirements are more stringent; At the same time, the containers cooled after hot charging to form a vacuum shall be sealed without gas intrusion

ease of opening and resealing from the perspective of convenience for consumers to drink, all kinds of container covers should have ease of opening. With the development of large capacity bottles, especially fruit juice carbonated drinks, they should also have the function of re sealing after opening, that is, re sealing. In this case, it is required to keep the aroma or carbonated gas in the container

anti theft in some cases, container caps (mainly bottle caps) are required to have anti-theft function to prevent theft and resale. In addition to the structure of the cover itself, the container cover must be sealed with sealing gasket or sealant. These materials should be elastic to maintain the pressure sealing state. For unscrewing the cover, the gasket should also withstand the friction of the sealing surface and can be unscrewed at a certain torque

classification of container caps

bottle caps

the caps used for sealing the mouth of glass bottles include crown caps, screw caps, spiral stop caps and wide mouth caps

(1) crown cap. Crown cap is a commonly used sealing cap for glass bottles. The crown cap was invented by William painter of Baltimore and patented in 1892. At present, it is widely used as the sealing cap of small mouth bottles. The crown cover is made of ordinary tinplate, which is bonded or injected with gasket after stamping. Cork was first used as the backing material, and later rubber, aluminum foil, plastic and other materials were developed. At present, PVC and other plastic backing are widely used. The liner should be flat without defects, firmly bonded to the bottle cap, and have a certain degree of elasticity and toughness. It should be sealed and cannot become a pollution source at the same time. The cushion material is generally natural rubber, and plastic material can also be used. These materials must be non-toxic, free of peculiar smell, and their soaking solution should not be colored or fluorescent. The bottle cap should have good corrosion resistance, and the paint film of the bottle cap should have good wear resistance

at present, crown "graphene has a great use space in the automotive industry. The cover is widely used in the sealing of beverage bottles. It can not only complete all the testing process automatically. Whether it is disposable bottles or inflatable and non inflatable beverage bottles, the crown cover is used. The crown cover has good pressure resistance and sealing performance, but it does not have resealing performance, and the ease of opening is poor.

(2) Screw cap. Screw covers include three kinds of continuous screw covers, including deep thread, shallow thread and general thread, as well as intermittent screw covers. Its size and category are marked with diameter (mm) and numbers representing corresponding characteristics, such as general continuous screw covers with a diameter of 28mm. Nominal diameter refers to the outer diameter near the top of the screw cap. However, all dimensions and nominal values are expressed in inches

twist off the screw cover. There are intermittent lines at the lower part of the screw cover, which divides the cover into two parts. It can be opened by twisting the scribed line, and the lower part is left at the mouth of the bottle, leaving traces of opening, which cannot be restored. The broken remnant cover turns into an ordinary screw cover, so it is particularly theft-proof and resealable. Screw caps can be made of tinplate, aluminum, plastic and other materials, depending on the bottle type and purpose. Like other types of covers, the reliability of screw covers also depends on the elasticity of the gasket and the flatness of the sealing surface of the container. The tightness of the screw cover should maintain an appropriate unscrewing torque under the condition of ensuring sealing, so that consumers can easily open it

(3) stop screw cap. This kind of cap is used for small mouth bottles and wide mouth bottles with threads. The flange of the cap is locked with the thread stop line of the bottle mouth thread, which is also known as flange cap, bayonet cap and unscrew cap. The rotation stop line at the glass bottle mouth has a spiral angle, which changes gradually in the whole screw process, and becomes straight in the end. The distance from the sealing surface to the straight rotation stop line is very limited. Therefore, there are 4 lugs on the cap, and the glass bottle mouth has 4 discontinuous thread lines. When opening the cap, it is easy to unscrew the cap with less than 1/4 turn. Therefore, it is commonly known as four screw bottle cap. Of course, according to the requirements, it can also be made into a six screw bottle cap

this screw cap is made of tinplate and other materials, and the sealing surface on the inner side of the cover is provided with PVC sealant. After tightening the cover, it will be sealed. It has good re sealing performance and can be used repeatedly

no matter three piece cans or two piece cans, the can body and the can cover are connected by double crimping, and the inner side of the edge of the can bottom cover is coated with sealing glue of ammonia glue, solvent glue and other materials, so the perfect sealing can be obtained after crimping. The tank cover is made by cutting plates, punching covers, rounding edges, injecting glue and drying. There is an expansion ring in the tank cover, because in the process of heating and sterilization after sealing, the tank cover expands when the pressure in the tank rises, and recovers after cooling, so as to prevent distortion of the crimping part of the can. Most of the easy opening covers are used for carbonated drinks, wine and other beverage cans. The feature of the easy opening cover is that there is a punch line (scribed line) in the opening part, and the punch line part can be opened easily. According to the opening mode, the easy opening cover can be divided into pull ring type and button type. Pull ring easy opening lid is widely used in inflatable drink cans

easy opening cover requires high purity of materials. Generally, aluminum alloy is used, but when aluminum Taijin easy opening cover is combined with iron anti can, it is easy to produce bimetallic corrosion. For the contents with high acidity, it is more serious to adopt 18 carbon fiber composite fan blades developed by Safran and ceramic matrix composite turbine parts developed by General Electric Company of the United States. Therefore, tinplate can be used to replace aluminum alloy cover, Coating can also be applied to the contact part between aluminum alloy and can body

source: world economist

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