Soft TPU Research Published in "PU Magazine"

This paper introduces Kuraray’s bio-based polyester polyol based on MPD and sebacic acid and discusses its potential for designing plasticizer-free soft TPU with heat resistance and low water absorption.
The study was first presented at the Polyurethanes Technical Conference, one of the leading technical conferences organized by the Center for the Polyurethanes Industry (CPI) of the American Chemistry Council.
The research has now been published in PU Magazine, an international trade publication covering technical innovations and market developments in the global polyurethane industry.

In this study, Kuraray used the MPD sebacic series, a bio-based polyester polyol based on MPD and sebacic acid.
The methyl-branched structure of MPD helps suppress crystallization, contributing to a liquid state and low viscosity at room temperature. In addition, the long carbon chain of sebacic acid contributes to flexibility and low water absorption.

These polyol properties make the series suitable for soft TPU design and provide the basis for evaluating plasticizer-free formulations in this study.

• Liquid at room temperature
• Low viscosity and easy handling
• Contributes to flexibility
• Low water absorption
• Bio-based raw materials

Conventional crystalline polyester polyols often require plasticizers to achieve low-hardness TPU. In contrast, the MPD sebacic series combines the crystallization-suppressing effect of MPD’s branched structure with the flexibility provided by sebacic acid’s long carbon chain.

As a result, the polyol itself contributes to TPU softness, making it possible to explore low-hardness TPU design without relying on external plasticizers. In this study, the resulting TPU formulations were evaluated for softness, heat resistance, and low water absorption.

• Softness without relying on plasticizers
• Heat resistance
• Low water absorption
• Broad molecular-weight lineup (500 to 6,000)