China Polypropylene Patent Infringement Dispute – Milliken & Company v. Haitian Shihua

Date: 26 August 2021

World-renowned American industrial manufacturer Milliken & Company (“Milliken”) accused China Xuzhou Haitian Shihua (“Haitian”) of patent infringement in 2019, claiming that the polypropylene (PP) product model “RP368T” falls within the scope of one of its patents CN103391966B (“CN’966 patent”), and requested compensation for damage of RMB 8.5 million. China Guangzhou Intellectual Property Court has recently ruled in favor of Haitian at first instance, holding that the product does not fall within the claims of the CN’966 patent. This case has drawn attention in the plastics industry as both parties enjoy a certain level of fame and influence in the field.

Background

In May 2019, Milliken purchased the model “RP368T” product manufactured by Haitian from a plastic distributor in Dongguan, China. After comparison, Milliken believed that the product has infringed its CN’966 patent, which was filed in 2011 and granted in 2015. Said product is manufactured with the method claimed in the patent, according to Milliken, who then proceeded to accuse Haitian of patent infringement.

Technical features of the CN’966 patent

The CN’966 patent relates to a thermoplastic polymer composition comprising an additive composition and method for manufacturing the same. The main technical feature is that the additive composition comprises a clarifying agent and a coloring agent, and the amount of coloring agent present in the thermoplastic polymer composition is sufficient to produce a thermoplastic polymer composition exhibiting a Δa* value and a Δb* value satisfying each of the following inequalities:

Δb*≤0–(2.8571×Δa*)

Δb*≥-1.5231+(5.8461×Δa*)

Δb*≥-2.6000-(1.0909×Δa*)

Δb*≤0+(1.2727×Δa*)

wherein Δb* is not zero; wherein the Δa* value and the Δb* value are calculated by measuring an a* value and a b* value exhibited by a 1.27 mm (50 mil) plaque made from a control thermoplastic polymer composition, measuring an a* value and a b* value exhibited by a 1.27 mm (50 mil) plaque made from the thermoplastic polymer composition, and subtracting the a* and b* values for the plaque made from the control thermoplastic polymer composition from the a* and b* values for the plaque made from the thermoplastic polymer composition; and wherein the control thermoplastic polymer composition contains the thermoplastic polymer and the clarifying agent but does not contain the coloring agent.

The CN’966 patent manufactures the thermoplastic composition with specific color space mainly by having the amount of the coloring agent satisfy the inequalities.

Haitian’s Defense

Haitian pleaded at first instance with the following reasoning: first, Milliken has no evidence proving the technical means taken to manufacture the product falls within the claimed scope of protection. Second, the product employs known art, which does not constitute infringement. Further, Milliken’s patent lacks novelty and inventiveness and should be invalidated.

Guangzhou Intellectual Property Court’s Opinion

The Guangzhou Intellectual Property Court considered that the additive composition described in the CN’966 patent is mainly comprised of a clarifying agent and a coloring agent, and the parties’ disagreement lies mainly in the coloring agent rather than the clarifying agent. Thus, how the definition should be interpreted and determining the scope of claims is key to the case.

The court held that adding a clarifying agent and a small amount of coloring agent to adjust color space of the thermoplastic composition is known art before the date of filing the patent application. Therefore, the patentee should bear the burden of proving that the infringer did in fact manufacture the model “RP368T” product according to the technical means of the CN’966 patent, i.e., adjusting the amount of coloring agent so that the thermoplastic composition satisfies the inequalities. However, Milliken has no evidence to prove that Haitian indeed adopted the technical means of the CN’966 patent.

Furthermore, in addition to the amount of the coloring agent, other materials or manufacturing process of the thermoplastic composition may also affect the color space of the product. As a result, even though the composition of the product manufactured by Haitian is exactly the same as the embodiments recorded in the CN’966 patent, or also has the same color nature as what the CN’966 patent claimed, it does not suffice as proof that Haitian indeed took the method of the defined inequalities to obtain the amount of coloring agent. Therefore, the Guangzhou Intellectual Property Court deemed that the model “RP368T” product is not considered an infringement.

This case has been further appealed to the China Supreme People’s Court, where Milliken has submitted evidence showing that the product is manufactured according to the embodiments in its CN’966 patent. It would be interesting to see how the case unfolds.

Wisdom Suggested Strategies

The patent claims that “the amount of coloring agent present in the thermoplastic polymer composition is sufficient to produce a thermoplastic polymer composition exhibiting a Δa* value and a Δb* value satisfying each of the following inequalities…”. By this definition, how the claim should be interpreted remains arguable, i.e., whether the product is considered an infringement on the patent as long as it fulfills the inequalities, or if the patentee should prove that the product is manufactured according to the technical means of the patent with an adjustment to the coloring agent.

Nonetheless, the court pointed out that in the field of plastic composition, adding a small amount of coloring agent to adjust the transparency of the composition is considered as known art before the date of filing the patent application. By this logic, the claim should be interpreted as “the amount of coloring agent present in the thermoplastic polymer composition is determined by satisfying the inequalities” for the product to be within the scope of the patent. Otherwise, it would not be reasonable either from the perspective of prior art defense or the validity of the patent per se.

In conclusion, this patent is in fact a process patent. Both Article 61 of Patent Law of the People's Republic of China and Article 99 of the Taiwan Patent Act similarly provide that unless the product manufactured with the claimed manufacturing process are unknown domestically and abroad, the patentee shall bear the burden of proving that the product is indeed manufactured based on said process. The patentee in this case did not produce convincing evidence at first instance. However, the case has been appealed to the China Supreme People’s Court and remains open to possibilities.

 

 

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