Types of open-mouth, flat-bottom bags

　　Open-mouth, flat-bottom bags are manufactured by extrusion-compression molding using photopolymerizable resin, kraft paper, and woven fabric as raw materials, which are then laminated into a single composite sheet. After the bag film and photographic images are aligned at both ends and stretched, an environmentally friendly adhesive is applied; following manual stretching, the material is sealed and cut to form various types of packaging bags. The kraft paper layer is further reinforced with a glossy oil-coated paper overlay for added structural strength and concealment. The compressive strength can be customized between one and six layers according to specific requirements. Packaging printing and manufacturing are integrated into a single process, with typical examples including square-bottom valve bags—such as three-layer kraft paper bags combined with a single PE film layer—which provide excellent waterproof and moisture-proof performance, delivering outstanding leak-proof results!

　　Types of open-mouth, square-bottom bags: internal valve and external valve openings. Product advantages: fully eco-friendly and green products; diversified material options; compliance with various product packaging regulations, including environmental protection and import/export packaging requirements; suitable for food packaging; exquisite printing and aesthetically pleasing bag designs; large capacity; stand-up pouch style; ideal for automated filling by packaging machinery. Polypropylene-coated woven open-mouth, square-bottom bags are manufactured on the basis of coated packaging bags, with dimensions customizable according to customer specifications. Heat-sealing technology is employed to achieve either side seals or a seal at the bag opening. Application areas: widely used for packaging powdered and granular products such as chemical raw materials, new construction materials, high-tech materials, pharmaceutical additives, food additives, tapioca starch, vegetable cream, plastics, and more. When stacked, square-bottom valve bags can be placed on pallets and wrapped with stretch film, meeting international standards.

　　Advantages of open-mouth square-bottom bags: The use of open-mouth square-bottom bags simplifies and streamlines many operations. When packing, the item to be packaged is manually kneaded from the inside to close the valve, achieving a secure seal. A square valve slot is sewn into the bag, leaving an opening for machine filling; after the product is packaged, it is fed through this opening into the valve slot under pneumatic or mechanical pressure. Square-valve bags include color-printed knitted-fiber valve bags, paper–plastic composite valve bags, and kraft-paper clip–plastic-film valve bags. Key features of these bags include being odorless, environmentally friendly, and compliant with national standards. Thanks to the cost-effectiveness of paper printing, custom graphics and text can be printed on the bags according to customer specifications. Valve paper bags made from such materials are highly convenient and efficient in the packaging of wheat flour, increasing packaging speed by up to three times, eliminating dust emissions, and improving the working environment. Moreover, because the filled valve bags are square-shaped, they stack easily and are not prone to rolling, allowing storage capacity to increase by 10% under the same storage conditions without affecting the handling process or the attire of operators.

　　Open-mouth, square-bottom bags offer superior compressive strength compared with paper bags, are reusable, and exhibit excellent water resistance. The advantages of square-bottom bags include markedly effective protection and strong shock-absorbing performance.