Block Bottom Bag – Easy Open

Our Easy Open Block Bottom Bags are manufactured on fully integrated, automated Starlinger production lines, ensuring superior consistency, strength, and precision from raw material to finished sack. The process is a continuous, seamless operation that can be broken down into four key stages:

1. Extrusion, Tape Making & Weaving

· Extrusion: Polypropylene (PP) or High-Density Polyethylene (HDPE) granules are melted and extruded into a continuous film.

· Tape Production: The film is slit into narrow tapes, which are then stretched (oriented) to create high-tenacity, low-elongation fibrillated or flat tapes. These tapes form the structural backbone of the bag.

· Circular Weaving: The tapes are fed into Starlinger circular looms, where they are woven into a seamless, tubular fabric. This method produces a stronger, more uniform sack body compared to traditional flat weaving, as it eliminates the side seam and distributes stress evenly.

2. Lamination & Printing

· In-line Lamination: The woven tubular fabric immediately enters the lamination unit. Here, a molten film of PP or PE is extruded directly onto the fabric surface(s) in a process called extrusion lamination or coating. This creates a moisture barrier, enhances sift-proofness, and provides a smooth surface for printing.

· High-Quality Printing: The laminated tube proceeds to a central impression cylinder (CIC) flexographic printing press. Precise tension control and registration on the Starlinger line allow for high-resolution, multi-color (up to 8 colors) printing with perfect repeat accuracy and sharp brand graphics.

3. Integration of Easy Open Feature & Bag Forming (Core Technology)

· Feature Application: This is a critical, in-line step. A specially designed tear tape (tear thread) is precisely fed and bonded into the laminated fabric at the exact predetermined position. Alternatively, a laser scoring/perforation system can be used to create a precise, weakened line. This integrated process guarantees the easy-open function's reliability and correct placement in every single bag.

· Cutting & Bottom Forming: The printed tube is precisely cut into individual bag sections (bag lengths). Each section is then fed into the block bottom forming unit:

· The bottom is folded into a cross-bottom (also called a satchel bottom) structure.

· The overlapping flaps are sealed using high-frequency (HF) welding or hot air welding. This creates a strong, leak-proof, and pin-hole free flat bottom, superior in strength and integrity to sewn bottoms. The bag can now stand upright stably.

4. Top Closure, Final Processing & Quality Control

· Top Sewing/Sealing: The top of the bag is finished according to specification—typically with a strong, secure sewing (using a hem or without) on industrial sewing machines. A press-tape closure can also be applied for re-closability.

· Automated Handling & QC: Throughout the process, integrated sensors monitor tape tension, coating thickness, print registration, and seal strength. Finished bags are automatically counted, stacked, and bundled. This high level of automation ensures consistent quality, minimal waste, and traceability.

Key Process Advantages:

· Seamless Integration: A true "from granule to bag" process reduces handling, contamination risk, and quality variance.

· Superior Seal Integrity: Welded block bottom offers better moisture protection, sift resistance, and burst strength compared to sewn bottoms.

· Precision Functionality: The easy-open feature is not an add-on but an in-line integrated function, ensuring consistent performance.

· High Efficiency & Consistency: Starlinger lines are renowned for high output, low downtime, and exceptional product uniformity, ensuring reliable supply for large-scale orders.

Key Features & Benefits:

1. Patented Easy Open Feature:

· Effortless Opening: A specially designed tear thread or laser-perforated line allows the bag to be opened quickly, cleanly, and safely with a single pull—no knives or tools required. This enhances user safety and operational speed on packaging lines.

· Clean Spout: Creates a neat, controlled pour spout, minimizing product dust and spillage.

2. Unmatched Strength & Durability:

· Woven Polypropylene Construction: Provides exceptional tensile and tear strength, ensuring excellent load-bearing capacity and resistance to rough handling during transport and storage.

· Block Bottom Design: The flat, stable base allows the bag to stand upright securely, simplifying palletization, storage, and shelf presentation. It also provides a larger surface for clear product branding.

3. Premium Manufacturing with Starlinger Technology:

· Precision Weaving: Starlinger looms produce fabric of consistent, high quality with optimal weave density for strength and barrier properties.

· Advanced Converting: The bag is seamlessly produced in a continuous, automated process (from tube weaving to printing, laminating, and cutting/sewing) ensuring superior seam integrity, precise dimensions, and flawless print registration.

· Customizable Lamination: Available with high-quality polypropylene or polyethylene laminations to provide essential moisture barrier properties, enhance print brilliance, and improve sack cleanliness.

4. Superior Print Quality & Branding:

· The smooth laminated surface allows for high-resolution, multi-color flexographic or rotogravure printing. Your logo, instructions, and safety warnings are displayed with exceptional clarity and visual impact, maximizing brand presence.

5. Reliable Closure:

· The bag is securely stitched at the top with strong thread (e.g., hot air sewn or sewing with hem) and can be supplied with a reliable press-tape closure or sewing for product security after the initial easy-open feature is used.

· Fertilizers & Agricultural Chemicals

· Animal Feed & Pet Food

· Building Materials (Cement, Sand, Dry Mixes)

· Minerals & Powders

· Food Products (Sugar, Salt, Grains)

· Any dry flowable industrial product