The Production Process of Self - Sealing Bags---E

2025-01-17 17:45:29

	Self - sealing bags are widely used in various industries for packaging due to their convenience and practicality. Here is a detailed introduction to their production process.

	
		Raw Material Preparation

Plastic Resin Selection: High - density polyethylene (HDPE) or low - density polyethylene (LDPE) is commonly used for making self - sealing bags. These resins offer good flexibility, durability, and transparency. The choice between HDPE and LDPE depends on the specific requirements of the bag, such as thickness, strength, and flexibility. For example, if a stronger and more rigid bag is needed, HDPE might be preferred; while for a more flexible and softer bag, LDPE is a better option.

Additives Incorporation: To enhance certain properties of the plastic, additives are added. These can include antioxidants to prevent the plastic from deteriorating due to oxidation, UV stabilizers to protect it from sunlight damage, and colorants if a specific color for the bag is desired. The amount of additives is carefully calculated based on the properties the final product needs to possess.

	
		Film Extrusion

Melting the Resin: The selected plastic resin, along with the additives, is fed into an extruder. The extruder heats the resin to a specific temperature, typically between 150 - 300 degrees Celsius, depending on the type of resin. This high temperature melts the resin, turning it into a viscous liquid state.

Film Formation: The melted resin is then forced through a flat die or a circular die. When passing through a flat die, a flat film is formed, while a circular die results in a tubular film. The thickness of the film is controlled by adjusting the speed of the extruder and the gap of the die. For self - sealing bags, the film thickness usually ranges from 0.02 - 0.1 millimeters.

	
		Seal Strip Attachment

Extrusion of Seal Strip Material: A special type of plastic material with good sealing properties is extruded separately. This material is often a blend of polymers that can bond well with the main body of the self - sealing bag.

Lamination: The extruded seal strip is laminated onto one or both sides of the film. This can be done using heat and pressure. The heat softens the materials, allowing them to bond together, while the pressure ensures a strong and even connection. The width of the seal strip is typically around 5 - 15 millimeters, depending on the size and intended use of the self - sealing bag.

	
		Bag Shaping and Cutting

Cutting to Size: The film with the attached seal strip is then fed into a cutting machine. The cutting machine is programmed to cut the film into the desired size and shape of the self - sealing bag. Common bag sizes range from small snack - sized bags, which might be 5 x 8 centimeters, to large storage bags that could be 30 x 40 centimeters or even bigger.

Sealing the Sides: After cutting, the sides of the bag are sealed using heat - sealing techniques. Heat - sealing bars or rollers apply heat and pressure to the edges of the film, fusing the layers together to form a leak - proof seal. The sealing temperature and time are carefully controlled to ensure a strong and reliable seal.

	
		Quality Inspection

Visual Inspection: Each self - sealing bag is visually inspected for any defects such as holes, tears, uneven seals, or incorrect color. Bags with any visible flaws are removed from the production line.

Seal Strength Testing: A sample of the produced bags is randomly selected for seal strength testing. This involves applying a certain amount of force to the sealed part of the bag to check if it can withstand normal handling and use without opening. Bags that fail this test indicate a problem with the sealing process, and adjustments are made to the production parameters.

Dimensions Verification: The dimensions of the bags are also checked to ensure they meet the specified standards. This includes measuring the length, width, and thickness of the bags. Any bags with dimensions outside the acceptable tolerance range are discarded.

	After passing the quality inspection, the self - sealing bags are ready for packaging and distribution to various markets.

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The Production Process of Self - Sealing Bags---E

The Production Process of Self - Sealing Bags---E

Raw Material Preparation

Film Extrusion

Seal Strip Attachment

Bag Shaping and Cutting

Quality Inspection

QINGDAO BEAUFY GROUP