04/17/2026

Welding Instead of Gluing: Pinch-Bottom Bags Designed with Sustainability in Mind

Unlike the previous production method, the new pp*starKON X pinch-bottomer developed by Austrian machine manufacturer Starlinger closes the pinch bottom of the PP*STAR bag by welding and not by gluing. This makes the bag a mono-material packaging solution that is easy to recycle.

“When developing the new machine concept, it was important to us that the produced PP*STAR bags could be easily returned to the packaging loop,” explains Claudia Hagn, PP*STAR Product Manager at Starlinger. “For this, we were able to draw from our expertise in hot-air welding technology, which we have accumulated over the years with our AD*STAR bag technology. As a result, no adhesive is needed to secure the pinch bottom, which significantly simplifies the production and recycling of PP*STAR bags while simultaneously expanding their potential applications.”

Safe, lightweight, attractive—and recyclable

PP*STAR pinch-bottom bags are made from polypropylene tape fabric laminated with a reverse-printed BOPP film. This single-material composite not only gives PP*STAR bags their high durability and stability despite their comparatively low material weight, but also ensures good recyclability and an attractive appearance thanks to the customizable, high-quality printed BOPP film. From the fabric-film composite, pinch-bottom bags are manufactured in a fully automated process on Starlinger’s pp*starKON X pinch-bottom bag conversion system: first, a tube is formed from the flat fabric; then the individual pre-perforated bag sections are separated; and finally, the bag bottom is sealed using hot-air welding technology. With its unique technological features—including the specially designed hot-air sealing device and the patented laser unit—the pp*starKON X sets the standard for efficient, highly flexible and at the same time material-saving bag conversion.

The result is an attractive, lightweight, yet break-resistant and fully recyclable packaging solution with high resistance to tearing and puncturing. The durable PP*STAR bags not only help to significantly reduce breakage rates during the transport and storage of dry bulk goods such as animal feed, grain, rice, fertilizer, or construction materials, but they are also resistant to reactive chemicals. Their excellent barrier properties also reliably protect the contents from insect infestation or spoilage caused by microorganisms, which is particularly important when storing food and other sensitive goods.

Circular weaving technology up close

At the Starlinger booth at Chinaplas the RX 6.1^pro circular loom will be shown in operation. Designed for processing especially lightweight tapes, it produces tape fabrics for lightweight packaging such as the PP*STAR bag at a speed of up to 920 picks per minute and is characterized by its ease of operation and superior fabric quality.

Staying ahead of the curve—even in times of crisis

Low weight means less raw material usage—a key advantage of packaging made from woven plastic tapes. “Especially in times like these, when plastic packaging manufacturers are struggling with high raw material costs, woven packaging stands out: Thanks to its reduced weight, it has the lowest production costs while offering the best protection for the contents,” said Harald Neumüller, CSO of Starlinger. “Starlinger machines not only operate with optimized raw material usage but are also energy-efficient, highly productive, and generate minimal waste. To further reduce packaging production costs, CaCO₃ can be added during the process, and high shares of recycled content can help offset raw material shortages.” Starlinger offers packaging manufacturers machine models with optimized investment costs that guarantee maximum efficiency, minimal waste, and top quality, featuring specially produced machine types such as the ad*starKON SE bag conversion line or the viscoSHEET SE PET sheet line.

Focus on circular economy

“Our main focus is on enabling closed-loop systems for plastic packaging that are profitable for manufacturers,” explains Neumüller. “And not only for woven packaging, but also for many other plastic products. Our bag production systems and PET sheet lines process recycled materials, while our plastics recycling lines ensure that used plastics from the industrial and consumer sectors stay in the loop and do not end up in nature or in landfills.” In the area of plastics recycling, Starlinger’s PET bottle-to-bottle recycling technology has been approved for food-contact applications by a number of multinational brand owners as well as by national and international authorities such as the U.S. FDA and the EFSA in Europe. Also for other post-consumer plastics such as PP, PE, PA, PLA, or PS, Starlinger offers proven processing solutions that produce top-quality—including food-grade—recycled plastics, that meet the highest global market standards.

Starlinger at Chinaplas, April 21–24, 2026, Shanghai: Hall 2.1, Booth F51

Note: ADSTAR^® and PPSTAR^® are registered trademarks of Starlinger. ADSTAR^® and PPSTAR^® bags are produced exclusively on Starlinger machinery.