Vinyl Recycling Technology: The Challenge of Achieving A 100% Internal Recycling Rate

In accordance with the "YKK Group Environmental Vision 2050," YKK AP is actively pursuing the 3Rs — reduce, reuse, and recycle — to minimize the generation of waste. As part of these efforts, we have worked to reduce and recycle vinyl scrap, achieving an internal recycling rate (reuse of scrap) of 100%.

The cornerstone of these efforts is "horizontal recycling" technology, which involves reusing scrap vinyl window material to manufacture new vinyl windows. Thanks to the development of this vinyl recycling technology, we are able to recycle up to 2,500 tons of vinyl scrap annually. Vinyl frames are made up of multiple layers of acrylic to maintain their visual appeal. In the past, most vinyl frames were white, but in recent years black has emerged as the leading choice; as a result, when these frames were shredded into scrap, the colors mixed together, making restoring them to pure white a difficult technical proposition.

To this end, YKK AP has developed a technology that allows the reuse of these scraps as a coloring material without the need for separating out the different colors. We developed a proprietary mold design based on dynamic analysis and introduced a "selective single-layer" technology. This approach involves using different materials for each component of the window frame, employing virgin material for visible surfaces and recycled material for less prominent areas. This "selective single-layer" method enables consistent production of vinyl frames, while also addressing design-related issues.

In addition, to ensure the quality of recycled materials, we have developed a dedicated "twin-screw Ssub-extruder" that allows direct feed-in of shredded material. Previously, recycling scrap material required a separate pelletizing process to ensure uniformity between the vinyl and acrylic fragments; however, the introduction of this machine has eliminated that step. Thanks to the powerful mixing action of the twin-screw system, even layered scrap material can be blended to a uniform consistency. This means that we can ensure properties equivalent to virgin material in terms of tensile strength, flex strength, and impact resistance.

Prior to implementing horizontal recycling, YKK AP also established recycling technology for the hard gaskets used in vinyl windows. Instead of purchasing virgin materials from external suppliers, we shred the vinyl scraps generated during the finishing process, mix them with coloring agents, and reprocess them into pellets to produce gasket components. Meanwhile, to address challenges such as the strain placed on manufacturing machinery due to differences in material properties and surface roughness, we repeatedly adjusted the mixture of additives and optimized pellet production conditions. This expertise in making recycled materials resemble the characteristics of virgin materials paved the way for our subsequent success of horizontal recycling.