Performance and appearance requirements for beverage container lid sealing technology

In recent years, with the continuous development of new types of beverage containers (such as various bottles, barrels, and cans), the lids of containers have also been introduced. Of course, although there are many types of container caps, its function is to ensure the sealing of the container, and it should also have good opening performance and novel appearance design.

Container cover should have the function

Sealing

The function of the lid is to ensure that the container is sealed and to protect the contents of the container so that it does not deteriorate during the shelf life. Therefore, all kinds of covers must first have airtightness and tightness to ensure that the contents are not in contact with the external environment, and do not leak; for carbonated drinks and other inflatable drinks, the airtightness requirements are more stringent; The vacuum container ensures that the seal is free from gas intrusion.

Openability and Resealability Various container lids should be easy to open in terms of consumer convenience. With the development of large-capacity bottles, especially fruit juice carbonated drinks, they should also have the function of opening and then sealing, that is, resealability. In this case, it is required to maintain the aroma of the container contents or carbon dioxide gas from being lost.

Anti-theft performance In some cases, the container lid (mainly the bottle cap) is required to have an anti-theft function to prevent theft and re-sale. The container lid guarantees the condition of the seal, in addition to the structure of the lid itself, it must also have a gasket or a sealant, etc. These materials should have a certain degree of elasticity in order to maintain the sealed state. For unscrewing the lid, the seal should also withstand the friction of the sealing surface, and at the same time can be unscrewed at a certain torque.

Container cover classification

Caps

Seals for glass bottle mouth seals include crown caps, screw caps, screw caps, and wide mouth caps.

(1) Crown cover. Crown caps are commonly used sealing caps for glass bottles. The Crown was invented by William Painter of Baltimore and patented in 1892 and is now commonly used as a small-mouth bottle closure. The crown cap material is an ordinary tinplate, which is glued or glued after stamping. The earliest use of cork materials for cork, and later the development of rubber, aluminum foil and plastic and other materials, is currently widely used plastic pads such as PVC. The liner should be smooth and defect-free, adheres firmly to the cap, and has a certain degree of elasticity and toughness. It must be sealed and it must not become a source of contamination. The liner material is generally based on natural rubber, but plastic materials can also be used. These materials must be non-toxic, odor-free and odor-free. The soaking solution should not be colored or fluorescent, and the bottle cap should have good corrosion resistance. The bottle cap paint film has good abrasion resistance.

Currently, the crown cap is widely used for the sealing of beverage bottles, whether it is disposable bottles or inflated, non-inflatable beverage bottles using crown caps. The crown cap has a good pressure tightness, but it does not have re-sealability and poor openability.

(2) Screw caps. The screw cap has 3 types of continuous screw caps, including deep thread, shallow thread and general thread. There are also interrupted thread caps. The size and type are marked with the diameter (mm) and the number indicating the corresponding characteristic. For example, 410-82 means that the diameter is 28mm. General continuous thread cap. The nominal diameter refers to the outer diameter near the top of the screw cap. However, all sizes and nominals are expressed in inches.

The twisted screw cap has a broken line in the lower part of the screw cap and divides the cover into two parts. The broken line can be opened and the lower part left in the bottle, leaving open traces that cannot be restored. The twisted residue is a common screw cap and is therefore particularly resistant to theft and resealing. Screw caps can be made of materials such as tinplate, aluminum and plastics, depending on the bottle type and use. Like other types of caps, the reliability of a screw cap is also determined by the elasticity of the liner, the flatness of the container closure surface, and the like. The degree of tightness of the screw cap should be maintained at a suitable twisting torque under the condition of ensuring the seal so that the consumer can easily open it.

(3) stop screw cap. This kind of cap is used for small-mouth bottle and wide-mouth bottle with screw thread. The flange of the cap flange is used to lock with the screw thread of the screw thread of the bottle mouth. It is also called the flange cap, bayonet cap and swing cap. The glass bottle mouth spin line has a helix angle that changes gradually throughout the screw stroke and becomes flat in the end. The distance from the sealing surface to the flat spin line is very limited. Therefore, there are four flanges on the cover, and there are four intermittent threads on the glass bottle opening. When the cover is opened, the cover can be easily unscrewed by less than 1/4 turn. Therefore, it is commonly called a four-rotary bottle cap. Of course, six-spiral caps can also be made on request.

This screw cap is made of tinplate and other materials. The inner sealing surface of the lid has a polyvinyl chloride sealant. After the lid is tightened, it is sealed. The sealability is good and it can be used repeatedly.

Can lid metal cans, whether they are three-piece cans or two-piece cans, the can body and can lids are joined by double crimping, and the inside of the bottom lid of the cans is coated with adhesive glues such as ammonia glue, solvent glue, etc. After the edge will be able to get a good seal. Can lid is made by cutting board, punching, round edge, glue injection and drying. There is an expansion ring in the lid of the can, because in the process of heat sterilization after sealing, the lid of the can expands when the pressure in the can rises, and then recovers after cooling, thereby preventing curling of the curled portion of the can. Easy to open the lid for the vast majority of carbonated drinks, wine and other canned beverages, easy to open the lid is characterized by the open part of the red line (marking line), open the red line can be easily opened. According to the opening method, the easy opening cover can be divided into a pull ring type and a button type. Pull-open easy-open covers are commonly used for inflatable beverage cans.

Easy-opening requires high purity of the material, and aluminum alloys are generally used. However, when the easy-opening cover of aluminum alloy gold is combined with iron-reverse cans, it is prone to bimetallic corrosion, and the content of the acidity is more serious. Instead of aluminum alloy lids, tinplates can also be coated with coatings that are in contact with the can body.