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Kraft paper bags are packaging bags made with kraft paper as the core base material. Leveraging kraft paper's high strength, tear resistance, and recyclability, they have become a universal packaging solution across industries such as manufacturing, food, and logistics. By structure, they can be categorized into open-top flat bags, square-bottom valve bags, and handle bags. In industrial settings, square-bottom/valve-style bags are predominant, serving as the classic packaging choice for powdered and granular materials. They accommodate standard industrial loads of 25-50kg and can also be customized in smaller sizes for lightweight packaging. valve-style bags are the primary choice for industrial applications, serving as the classic packaging solution for powdered and granular materials. They accommodate standard industrial load capacities of 25-50kg and can also be customized in smaller sizes for lightweight packaging.
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2026
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Suitable for standard moisture-proof applications without high cleanliness requirements for industrial powdered/granular materials. These are the go-to bags in the chemical and building materials industries. Leveraging their strong adaptability and low cost, they are the mainstream choice for 25-50kg standard packaging. Core applications:
05
2026
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Core Principle: Environmentally friendly water-based adhesive bonds the overlapping bottom seams, followed by pressing and drying to set the shape. This is the mainstream industrial process.
05
2026
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What are the manufacturing processes for square valve bags?
The manufacturing process for square valve bags centers on square-bottom forming and valve mouth processing, accommodating various substrates like all-paper or paper-plastic composites. It comprises four main stages: raw material pretreatment, core forming, valve mouth fabrication, and final shaping. Primary forming techniques include gluing the bottom and heat sealing, complemented by standardized processes like creasing, folding, and cutting. This process meets the load-bearing and sealing requirements for 25-50kg industrial packaging.
05
2026
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The square valve bag is a mainstream automated filling and packaging container in industrial applications. Named for its regular square base and specialized valve opening, it is also commonly referred to as a square-bottom valve bag or paste bag.
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2026
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