i4F Licensing NV v. Changzhou Subili New Materials Co Ltd

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: i4F Licensing N.V. (Belgium)
  • Defendant: Changzhou Subili New Materials Co. Ltd. (People's Republic of China); Zhejiang Eco New Material Co. Ltd. (People's Republic of China); and Artisan Floors Corporation (California)
  • Plaintiff's Counsel: Lowry Blixseth APC; The Webb Law Firm
• Case Identification: 2:26-cv-04985, C.D. Cal., 08/10/2026
• Venue Allegations: Venue is alleged to be proper as Defendant Artisan Floors Corporation resides and has a regular and established place of business in the district, and all Defendants have allegedly caused acts of infringement in the district through importation, use, and sale of the accused products.
• Core Dispute: Plaintiff alleges that Defendants' stone plastic composite (SPC) floor panels, and the methods used to produce them, infringe three U.S. patents related to the composition and manufacturing processes for composite covering panels.
• Technical Context: The technology pertains to the formulation and manufacturing of multi-layer composite flooring, a significant product category in the building materials and interior design markets, valued for its durability and aesthetic versatility.
• Key Procedural History: The complaint states that on January 25, 2026, Plaintiff sent a demand letter to Defendant Changzhou Subili New Materials Co. Ltd. identifying the alleged infringement. It also notes that Defendant Zhejiang Eco New Material Co. Ltd. is an existing licensee of Plaintiff for other, unrelated technologies, which may be used to suggest pre-suit knowledge of the patents-in-suit.

Case Timeline

Date	Event
2015-01-16	Priority Date for '918 Patent
2016-06-28	Priority Date for '396 Patent
2016-06-28	Priority Date for '753 Patent
2021-08-17	'918 Patent Issued
2023-10-24	'396 Patent Issued
2025-09-30	'753 Patent Issued
2026-01-25	Plaintiff sent demand letter to Defendant Subili
2026-08-10	First Amended Complaint for Patent Infringement Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 11,091,918 - "Covering Panel and Process of Producing Covering Panels"

• Patent Identification: U.S. Patent No. 11,091,918, entitled "Covering Panel and Process of Producing Covering Panels," issued August 17, 2021 (the "'918 Patent").

The Invention Explained

• Problem Addressed: The patent's background section identifies a significant shortcoming in prior art covering panels: a "definite tendency to curling" '918 Patent, col. 1:41-42 This curling is attributed to internal stresses and non-uniform composition, which manifest when panels are exposed to changing temperatures, leading to visual defects and delamination '918 Patent, col. 1:43-58
• The Patented Solution: The invention proposes to solve the curling problem by creating a panel with a substrate containing a specific, optimized amount of filler material-between 15% and 75% by weight-blended with a synthetic material like PVC '918 Patent, abstract '918 Patent, col. 2:1-8 The patent describes a process of mixing the components, extruding the mixture to form a substrate, laminating it to a top layer, and then annealing the panel to relieve stress '918 Patent, col. 2:16-31 '918 Patent, claims 1, 8 This composition and process are intended to produce a panel with high rigidity and reduced curling.
• Technical Importance: By focusing on the material composition and processing steps to control internal stress, the invention aimed to improve the dimensional stability and durability of composite flooring panels.

Key Claims at a Glance

• The complaint asserts independent claims 1 and 8 Compl. ¶42
• Independent Claim 1 is a process claim comprising the key elements:
  • A process of producing covering panels comprising a top layer and at least one substrate.
  • The substrate comprises a synthetic material and a filler material.
  • The process includes the steps of: (a) mixing the synthetic and filler materials, (b) extruding the mixture to obtain the substrate, (c) optionally laminating the substrate to the top layer, and (d) annealing the covering panel.
  • The filler material is mixed in an amount from 15 to 75 wt.% of the total mixture.
  • The substrate is attached to the top layer at a temperature higher than the softening point but lower than the melt temperature of the principal polymer in the substrate.
• The complaint reserves the right to assert additional claims Compl. ¶42

U.S. Patent No. 11,794,396 - "Method of Producing a Glueless Dustless Composite Flooring Material System"

• Patent Identification: U.S. Patent No. 11,794,396, entitled "Method of Producing a Glueless Dustless Composite Flooring Material System," issued October 24, 2023 (the "'396 Patent").

The Invention Explained

• Problem Addressed: The patent background identifies multiple issues with existing flooring: cores made from compressed sawdust are susceptible to water damage; the use of glues or adhesives adds manufacturing complexity and creates a risk of delamination; and finishing coatings often require long curing times, creating production bottlenecks '396 Patent, col. 1:21-47
• The Patented Solution: The patent describes a multi-layer, PVC-based flooring product and a method to produce it without glues or dust-based fillers. The solution involves creating a base layer from a PVC and calcium carbonate mixture, then fusing it to a face layer (itself comprising decorative and wear sublayers) via a "hot-melt overlaying" process '396 Patent, col. 7:59-65 The final product is coated with a plastic resin that is rapidly cured by exposure to UV light '396 Patent, col. 9:18-45 This integrated, glueless process is designed for efficient, continuous-run manufacturing.
• Technical Importance: The invention provided a method for creating a durable, waterproof composite flooring system while streamlining the manufacturing process by eliminating adhesives and long-cure-time coatings.

Key Claims at a Glance

• The complaint asserts claims 1-4 and 6-11, including independent claim 1 Compl. ¶42
• Independent Claim 1 is a product-by-process claim for a composite flooring segment, comprising the key elements:
  • A flooring base layer comprising a mixture of PVC resin and calcium carbonate, formed by extrusion, mold-forming, and cooling.
  • A waterproof flooring face layer (with decorative and wear sublayers) that is textured and fused onto the base layer by "hot-melt overlaying."
  • A cured waterproof flooring coating layer, which is the result of coating the face layer with a UV-curing plastic resin and then curing it with UV light.
• The complaint reserves the right to assert additional claims Compl. ¶42

U.S. Patent No. 12,427,753 - "Glueless Dustless Composite Flooring Material System"

• Patent Identification: U.S. Patent No. 12,427,753, entitled "Glueless Dustless Composite Flooring Material System," issued September 30, 2025 (the "'753 Patent").
• Technology Synopsis: The '753 Patent, similar to the '396 Patent, discloses a glueless and dustless composite flooring system made of PVC-based materials. It addresses the manufacturing complexities and delamination risks associated with using adhesives by teaching a system where waterproof layers are fused together. The invention also describes a rapidly cured UV top coating to provide a durable finish and enable efficient, continuous manufacturing '753 Patent, abstract
• Asserted Claims: Claims 1-5, 8-10, 14, 17-19, and 21-24 are asserted, including independent claim 1 Compl. ¶42
• Accused Features: The complaint alleges that Defendants' SPC flooring products infringe by incorporating the claimed features, including the specified base layer composition (PVC and calcium carbonate), a multi-part face layer with a textured surface, a glueless "hot-melt overlaying" fusion process, and a UV-cured coating Compl. ¶¶82-93

III. The Accused Instrumentality

Product Identification

• The accused products are stone plastic composite (SPC) floor panels and tiles manufactured by the Chinese Defendants and imported, sold, or offered for sale by all Defendants in the United States Compl. ¶11 Compl. ¶27

Functionality and Market Context

• The accused products are alleged to be composite flooring panels composed of an SPC substrate or core, which is a mixture of polyvinyl chloride (PVC) and a stone filler material such as calcium carbonate Compl. ¶26 Compl. ¶27
• The complaint alleges the products have a multi-layer structure, including an SPC core, a top layer, and in some cases an underlayment layer Compl. ¶31 Compl. ¶36 The top layer is described as including a decorative film layer, a PVC wear layer, and a UV cured coating Compl. ¶31 An exploded diagram from the defendants' marketing materials illustrates this layered construction Compl. p. 8, Ex. E
• The complaint alleges the products are manufactured by mixing PVC resin with calcium carbonate, extruding the mixture to form the core, and then laminating the core to the top layer using a "hot-melt overlaying process without glue" Compl. ¶¶32-34 A flowchart from the defendants' materials depicts a "Production Process" that includes steps for "Mixture," "Extrusion," and "UV coating" Compl. p. 9, Ex. D

IV. Analysis of Infringement Allegations

'918 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A process of producing covering panels...comprising...mixing the synthetic material and the filler material...wherein said filler material is mixed with said synthetic material in an amount from 15 to 75 wt. %...	Defendants manufacture the Accused Products by mixing a synthetic material (PVC) with a filler material (calcium carbonate) in an amount from 15 to 75 wt.%.	¶53	col. 2:21-31
...extruding said mixture, thereby obtaining the substrate...	The resulting mixture is extruded to obtain an SPC substrate.	¶53	col. 2:24-25
...laminating the substrate to the top layer...at a temperature higher than the softening point but lower than the melt temperature of the principal polymer comprised in said substrate.	A top layer is laminated to the substrate, which is heated to a temperature above the softening point of PVC but lower than the melting temperature.	¶54	col. 24:31-38
...annealing the covering panel.	The substrate is annealed after lamination.	¶54	col. 23:36-39

'396 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
...a flooring base layer comprising a mixture of PVC resin and calcium carbonate...wherein said flooring base layer is a resultant of extrusion of the mixture at elevated temperature and pressure, mold-forming the extruded mixture into said flooring base layer, and cooling said flooring base layer...	The Accused Products have an SPC core or base layer which is a mixture of PVC and calcium carbonate, created by extruding the mixture at an elevated temperature and pressure through an extrusion mold.	¶64; ¶65; ¶66	col. 6:40-67
...a waterproof flooring face layer comprising a decorative face sublayer and a wearing face sublayer...where said flooring face layer is textured and fused onto a top face of said flooring base layer by hot-melt overlaying of said layers...	The Accused Products have a face layer with a decorative and wearing sublayer that is textured and fused onto the SPC base layer by hot-melt overlaying.	¶67; ¶68; ¶69	col. 7:29-65
...a cured waterproof flooring coating layer...wherein said flooring coating layer is the resultant of coating said flooring face layer with a UV-curing plastic resin and UV curing said coating of UV-curing plastic resin by exposure to UV light.	A cured waterproof UV plastic resin coating layer is applied to the face layer and cured by exposure to UV light.	¶70	col. 9:18-45

Identified Points of Contention

• Factual Verification: For the '918 Patent, a central question will be whether the accused manufacturing process uses a filler-to-synthetic material ratio that falls within the claimed 15-75 wt.% range. The complaint makes this allegation "upon information and belief," indicating a likely area for discovery and expert testimony Compl. ¶53
• Process Step Equivalence: The '918 Patent requires an "annealing" step. The infringement analysis will question whether the defendants' manufacturing process includes a distinct step that qualifies as annealing (i.e., controlled heating and cooling to relieve internal stress), or if the cooling that occurs is merely incidental and does not meet the claim's requirement.
• Scope of "Hot-Melt Overlaying": For the '396 and '753 Patents, a key dispute may center on the construction of "hot-melt overlaying." The patents describe this as fusing layers together without glue by simultaneously applying heat and compression '396 Patent, col. 8:15-19 The case may turn on whether the defendants' lamination technique, alleged to be a "hot-melt overlaying process" Compl. ¶33 Compl. ¶69, performs this simultaneous function or operates in a materially different way.

V. Key Claim Terms for Construction

For the '918 Patent:

• The Term: "annealing"
• Context and Importance: This term recites a specific manufacturing step in claims 1 and 8. Infringement of these process claims hinges on whether the accused manufacturing method includes a step that meets the legal and technical definition of "annealing." Practitioners may focus on this term because if the defendants' process lacks this specific step, or if their cooling process does not qualify as "annealing," it could provide a basis for a non-infringement defense.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The term itself is not explicitly defined with limiting parameters in the claims, which may support an argument that any post-lamination heating and cooling process intended to stabilize the panel could qualify.
  • Evidence for a Narrower Interpretation: The specification states that the panel is annealed "to remove stress and achieve dimensional stability" and suggests specific process parameters, such as annealing "at a temperature above the glass transition temperature" for a certain duration '918 Patent, col. 23:36-49 This language may support a narrower construction requiring a deliberate, thermally-controlled stress-relief step, rather than just ambient cooling.

For the '396 Patent:

• The Term: "hot-melt overlaying"
• Context and Importance: This term is central to the asserted claims of the '396 and '753 patents, as it defines the glueless method of fusing the flooring layers. The core infringement question will be whether the defendants' lamination process falls within the scope of this term.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: A party might argue the term broadly covers any process where heat is the primary mechanism for fusing pre-formed layers, as distinct from using a separate adhesive.
  • Evidence for a Narrower Interpretation: The specification describes the process as "simultaneously heating and applying compression to the stack to fuse the layers together" '396 Patent, col. 8:15-19 The word "simultaneously" could be interpreted to require a specific type of machinery (e.g., heated rollers) that applies heat and pressure at the same time, potentially excluding processes where heat is applied first, followed by a separate pressure step.

VI. Other Allegations

• Indirect Infringement: The complaint alleges that the Chinese Defendants induced infringement by urging or encouraging third parties, including distributors and retailers such as Defendant Artisan, to import, sell, and use the Accused Products in the United States Compl. ¶56 Compl. ¶74 Compl. ¶95 This conduct is alleged to have been done knowingly or with willful blindness to the infringement Compl. ¶57 Compl. ¶75 Compl. ¶96
• Willful Infringement: The willfulness allegation against the Chinese Defendants is based on alleged pre-suit knowledge. This is supported by Plaintiff's demand letter sent to Defendant Subili and Defendant Zhejiang's alleged prior business relationship with Plaintiff as a licensee for other technologies Compl. ¶¶43-47 For Defendant Artisan, willfulness is alleged to have commenced upon service of the complaint, establishing post-suit knowledge Compl. ¶59 Compl. ¶77 Compl. ¶98

VII. Analyst's Conclusion: Key Questions for the Case

1. A central issue will be one of claim construction and technical scope: can the term "hot-melt overlaying," as described in the '396 and '753 patents, be construed to read on the defendants' specific lamination process? The resolution will likely depend on whether the process involves the "simultaneous" application of heat and pressure as taught in the specification.
2. A key evidentiary question will be one of factual compliance: can the plaintiff demonstrate through discovery and expert analysis that the accused products' material composition, specifically the weight percentage of calcium carbonate filler, falls within the 15-75% range required by the '918 patent's claims?
3. A third question will concern process verification: does the defendants' manufacturing method include a distinct, deliberate "annealing" step as required by the '918 patent, or is the cooling process merely an incidental part of production that does not meet the claim's requirement for a controlled, stress-relieving thermal treatment?