Date: 1 April 2026

【Volume 169】

In the 2025 Administrative Judgment (Xing Zhuan Su Zi No. 6), the Intellectual Property and Commercial Court (IPCC) addressed a pivotal invalidation action concerning an invention patent defined by specific parameters. The dispute centered on polyester film Patent No. I771892, which the IPCC ultimately found to lack an inventive step, thereby sustaining the Taiwan Intellectual Property Office's (TIPO) decision to invalidate the claims. By applying a rigorous "inherent property" doctrine to chemical materials and analyzing the "motivation to combine" among prior art references, this decision establishes a critical legal boundary for practitioners navigating numerical range limitations in patent claims.

Comparison Between the Technical Features of the ‘892 Patent and the Evidence

The ‘892 Patent aims to improve the recyclability of polyester containers through specific component compositions and physical property parameters, while also enhancing yield and production efficiency.

The following provides a detailed comparison between the ‘892 Patent and the primary evidence (Evidence 2 and Evidence 8):

IPCC’s Analysis : Why Were the Parameter Features Treated as “Inherent Properties”?

In this case, the IPCC adopted an exceptionally strict legal rationale that “identical compositions will give rise to identical properties”:

1. Physical changes do not give rise to new properties

The IPCC held that the physical properties of polyester films (such as melting point and crystallization temperature) are primarily determined by the types and proportions of the diol and diacid components of the resin. Although parameters in the film-forming process, such as the heat-setting temperature, may have some influence, the court considered such effects to be limited, because the process largely involves physical changes rather than the formation or cleavage of chemical bonds.

The plaintiff argued that the variations in processing conditions could lead to differences in physical properties. However, the IPCC found that any such differences would not be of a significant magnitude to confer an inventive step.

2. Effect of a Broad Parameter Range

The IPCC further observed that the melting point range defined in the ‘892 Patent (170 °C or higher) is broad in scope. Given identical compositions, the court reasoned that the resulting physical properties would not generally vary to such an extent as to fall outside the claimed range.

3. Functional Redundancy: The Relationship Between Means and Result

After analyzing the specification of the ‘892 Patent, the IPCC found that the parameters such as “melting point, crystallization temperature, and glass transition temperature” merely serve as specific means for achieving the objective of “reducing the gel fraction.” Since the claims have already defined a numerical range for the “gel fraction,” the court considered this feature sufficient to achieve the intended recycling performance. The remaining parameter features were therefore found not to provide any additional technical advantage.

4. Industry Motivation: The Rationale of Combining the Evidence

The IPCC found strong motivations to combine Evidence 2 (film technology) and Evidence 8 (recycling standards):

• Field relevance: Evidence 2 concerns container label films, while Evidence 8 sets forth criteria for assessing the recyclability of PET bottle labels.
• R&D motivation: When developing label films, a person ordinarily skilled in the art would have been motivated to consult commonly used industry guidance documents (Evidence 8) to ensure recyclability, and to adjust the relevant parameters accordingly.