BOPP Pinch Bottom Open Mouth (PBOM) Bags | Direct Heat Seal T-Shape Step-Cut Bags

BOPP Pinch Bottom Open Mouth (PBOM) Bags, commonly known in the industry as T-Shape Bags or Step-Cut Bags, are constructed from high-definition printed Biaxially Oriented Polypropylene (BOPP) film laminated with a high-strength inner layer. They are specifically engineered for high-efficiency and leak-proof pinch thermal sealing.

1. Structural Design & “Pre-Formed T-Fold” Sealing Principle

• Pre-Formed Step-Cut T-Fold Structure: During bag manufacturing, the bag top and bottom undergo precision multi-layer staggered step-cutting, pre-forming dedicated T-shape step folds (staggered gussets and face/back alignment). This design allows the bag mouth to fold neatly and overlap seamlessly after filling.
• Heat Sealing via Professional Pinch Sealer: After product filling, a specialized Pinch Sealer machine is required. The equipment folds the pre-formed T-shape flap and applies heat and pressure to melt and fuse the layers together (Thermal Melting). Upon cooling, it creates a permanent, high-strength welded seal that is 100% sift-proof.
• Side Gusset Construction (Box-Shape Effect): The side gussets expand fully after filling, forming a neat, rigid 3D box-like structure, which significantly optimizes pallet stacking stability and warehouse space utilization.

2. Key Advantages & Features

• 100% Sift-Proof & Moisture-Resistant: Heated and sealed by a professional pinch sealer, the T-fold area creates a fully enclosed weld seam, eliminating pinholes and preventing fine powder leakage or moisture ingress.
• Stable Box-Shape Pallet Stacking: Eliminates the “pillow shape” found in traditional sewn bags. The filled bag stands flat and neat, dramatically improving palletization efficiency during transit.
• 360° Shelf Appeal: Flat bottom and side gussets provide ample surface for high-definition reverse gravure printing, maximizing brand visibility.
• Superior Drop & Tensile Strength: The heavy-duty internal structure resists punctures, tears, and bursts during rough handling and long-distance shipping.

3. General Specifications & Technical Parameters

• Load Capacity: 5kg, 10kg, 20kg, 25kg, 50lb (Customizable)
• Size Range: Width 250 – 600 mm | Gusset 50 – 180 mm | Length 500 – 1100 mm
• Printing: 1–10 Colors Gravure Printing (BOPP Glossy, Matt, Selective Matt, Metallic)
• Optional Features: Easy Open Tape, Micro-perforation (Venting), Anti-slip Coating
• Typical Applications: Premium Pet Food (Dog/Cat Food), Agricultural Seeds & Fertilizers, Food Ingredients (Flour/Starch), Construction Chemicals (Tile Adhesive, Waterproof Powder).

4. Filling & Sealing Process Flow

1. Pre-Formed Bag Supply: Bags are manufactured with pre-formed T-shape fold corners and sealed bottoms, delivered open-mouth to the client.
2. Product Filling: Bulk materials are filled into the bag via automatic or semi-automatic filling machines.
3. Folding & Thermal Melting: The bag mouth enters a professional Pinch Sealer, which folds the pre-formed T-shape corner and heats it to melt-fuse the seal.
4. Cooling & Palletizing: Rapid cooling solidifies the sift-proof seal, preparing the bag for immediate flat pallet stacking.