Recently, the China National Intellectual Property Administration (CNIPA) issued Invalidation Decision No. 661068, fully invalidating the invention patent owned by ASK Chemicals GmbH, Patent No. 201380029798.6, titled “Moulding material mixture containing barium sulphate, mould or mould core, method for producing the same, and use of barium sulphate”. T&C represented the petitioner and attended the oral hearing of this case, achieving full invalidation of all claims 1 to 40.

Case Overview

The subject patent was filed on 6 June 2013, claiming priority dated 6 June 2012, and granted on 28 August 2018. It falls within the technical field of foundry moulding materials. The patent protects a moulding material composition comprising a refractory base moulding material, a water glass binder, barium sulphate, and particulate metal oxide. Its scope further covers processes for manufacturing moulds and cores, aluminium casting processes, and the use of barium sulphate in the foundry industry. With as many as 40 claims, the patent provides multi-dimensional protection spanning product, method and use claims, posing substantial patent barrier risks for domestic enterprises implementing relevant technologies in the foundry materials sector.

The petitioner filed a request for invalidation with CNIPA on 9 December 2025. After the case was accepted, T&C team continuously supplemented diverse evidence including comparative patent documents, national standards and professional technical manuals. Arguments were advanced on multiple grounds under the Patent Law, including lack of inventiveness under Article 22.3, ambiguity of claims, failure of claims to be supported by the specification, and insufficient disclosure in the specification. During the oral hearing, T&C team presented the complete chain of evidence and fully submitted our arguments. Following the oral hearing and panel deliberation, CNIPA finally held that all claims of the subject patent lacked inventiveness and rendered a decision of full invalidation.

Core Technical Disputes and Representation Strategy

The core dispute of this case lies in the assessment of inventiveness for a composition invention patent.

The distinguishing technical feature of Claim 1 of the subject patent over the closest prior art is the addition of barium sulphate within a specific particle size range to improve casting surface quality. The core representation strategy adopted by our team is outlined below:

      - Two key comparative patents were retrieved. Evidence 1 discloses the basic system of foundry moulding materials consisting of water glass, refractory substrate and particulate metal oxide. Evidence 2 already discloses the addition of barium sulphate to foundry sand to improve casting surface quality and reduce blowhole and pinhole defects, disclosing both the function and dosage range of barium sulphate.

      - Evidence from technical manuals reflecting common general knowledge establishes that selection of particle size for barium sulphate (barite powder) represents a conventional technical measure in the field. The particle size range of 0.1 μm–90 μm is a routinely available option in the industry, and the technical effects achieved by such selection are foreseeable to a person skilled in the art, with no unexpected technical effect obtained.

      - For dependent claims, method claims and use claims, arguments were made one by one: their additional technical features are either already disclosed in prior art or represent conventional optimisation choices in the field. Given that the independent claims lack inventiveness, all dependent, method and use claims are likewise devoid of inventiveness.

The panel adopted T&C's arguments. The key holding of the decision states: where a claim differs from prior art by a distinguishing technical feature, but such feature constitutes a conventional technical choice adopted by a person skilled in the relevant field, and the effects achievable by such choice are clearly foreseeable, the technical solution claimed in such claim fails to satisfy the substantive requirement for inventiveness. On this basis, all 40 claims were found non-compliant with the inventiveness requirement under Article 22.3 of the Patent Law, and the patent was fully invalidated.

Business Value of the Case

Removal of industry patent barriers

Full invalidation of this foreign-related patent eliminates patent infringement risks for domestic foundry material enterprises implementing relevant formulations and processes, enabling industry players to lawfully practise such water glass-based foundry moulding material technical solutions.

Precedent for handling composition patent invalidation cases

This case illustrates the reasoning for invalidation of chemical/material invention patents: identifying the closest prior art, pinpointing distinguishing technical features, and proving that distinguishing features are conventional technical choices through combined evidence of patent literature and common general knowledge manuals. It serves as a typical approach for challenging the validity of composition patents.

Demonstration of professional capability

T&C possesses full-spectrum capabilities for patent invalidation proceedings, specialising in patent confirmation cases in the chemical, materials and mechanical manufacturing sectors. We provide end-to-end solutions for patent invalidation, including infringement risk analysis, prior art retrieval, evidence excavation, drafting of invalidation petitions, response to office actions, and representation at oral hearings, helping enterprises resolve patent threats and clear intellectual property obstacles in business operations.