Trade Associates v. Biologix USA Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Trade Associates, Inc. (Washington)
  • Defendant: Biologix USA, Inc. (Wisconsin)
  • Plaintiff's Counsel: Dorsey & Whitney LLP
• Case Identification: 2:26-cv-05600, C.D. Cal., 05/26/2026
• Venue Allegations: Venue is asserted based on Defendant's principal place of business being located within the Central District of California, where a substantial part of the alleged infringing events occurred and where Defendant maintains a regular and established place of business.
• Core Dispute: Plaintiff alleges that Defendant's conformable sanding blocks infringe three patents related to the specific chemical compositions and manufacturing methods for such blocks.
• Technical Context: The technology concerns elastomeric sanding blocks designed for the automotive and marine refinishing industries, which are engineered to be flexible enough for curved surfaces yet rigid enough for flat surfaces, solving a common problem with traditional sanding tools.
• Key Procedural History: The complaint alleges that Plaintiff previously reported infringement of the '403 Patent to Amazon through its Patent Evaluation Express (APEX) program, resulting in the takedown of Defendant's product listings. This event is cited as the basis for Defendant's alleged actual notice and subsequent willful infringement.

Case Timeline

Date	Event
2012-10-02	Priority Date for '403, '847, and '103 Patents
2016-08-30	U.S. Patent No. 9,427,847 Issued
2017-08-15	U.S. Patent No. 9,731,403 Issued
2022-04-05	U.S. Patent No. 11,292,103 Issued
2025-08-27	Plaintiff initiates first APEX submission against Defendant
2025-09-23	Plaintiff initiates second APEX submission against Defendant
2026-05-26	Complaint Filed

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

U.S. Patent No. 9,731,403 - Hand-Held Conformable Sanding Block

• Patent Identification: U.S. Patent No. 9,731,403, "Hand-Held Conformable Sanding Block," issued on August 15, 2017.

The Invention Explained

• Problem Addressed: The patent's background describes the shortcomings of traditional sanding blocks, such as those made of wood or cork, which are too rigid for curved surfaces common on automobile bodies Compl. ¶11 This rigidity can lead to uneven sanding, a "rippling effect," and surface damage from the application of excessive pressure (Compl. ¶11; Compl. ¶12, Compl. ¶¶col. 1:35-50).
• The Patented Solution: The invention is an elastomeric sanding block that balances rigidity for flat surfaces with pliability for curved ones Compl. ¶12 As detailed in the specification, this is achieved through a specific composition comprising ethylene-vinyl acetate (EVA) copolymer as the sole polymeric component, combined with a blowing agent to create a foam structure with a target Shore A hardness range of about 30 to 90 '403 Patent, col. 2:7-17 '403 Patent, abstract
• Technical Importance: The invention provides a single tool capable of effectively sanding both flat and complex curved surfaces, addressing a persistent need in the automotive repair and restoration industry for tools that prevent surface defects Compl. ¶12

Key Claims at a Glance

• The complaint asserts independent product claim 6 and independent method claim 12 Compl. ¶37
• Independent Claim 6 (Product Claim) requires:
  • An elastomeric sanding block conformable to curved or flat surfaces;
  • A Shore A hardness from about 30 to about 90;
  • Made from a composition comprising a polymeric component that consists of ethylene-vinyl acetate (EVA) copolymer;
  • The EVA copolymer is in an amount from about 35% to 70% of the composition by weight; and
  • A blowing agent is in an amount from about 1.5% to 4.5% of the composition by weight.
• Independent Claim 12 (Method Claim) requires:
  • Providing a composition with a polymeric component of EVA copolymer (35% to 70% by weight);
  • Combining the EVA copolymer with a blowing agent under heat to create a feedstock;
  • Thermoforming the feedstock in a mold to yield a foamed material sheet; and
  • Cutting the sheet to yield the elastomeric sanding block.
• The complaint notes that additional claims may be asserted later Compl. ¶37

U.S. Patent No. 9,427,847 - Hand-Held Conformable Sanding Block

• Patent Identification: U.S. Patent No. 9,427,847, "Hand-Held Conformable Sanding Block," issued on August 30, 2016.

The Invention Explained

• Problem Addressed: The patent addresses the same problem as the '403 Patent: the inadequacy of conventional sanding blocks for sanding both flat and curved surfaces in applications like automotive bodywork '847 Patent, col. 1:25-50
• The Patented Solution: This patent discloses a similar elastomeric sanding block, but its composition is based on an "admixture" of two different polymers: ethylene-vinyl acetate (EVA) copolymer and low-density polyethylene (LDPE) homopolymer '847 Patent, abstract The specification explains that blending these two polymers allows for the creation of sanding blocks with varying degrees of hardness and rigidity, tailored for different sanding purposes '847 Patent, col. 3:4-8 The composition also includes a blowing agent and a pigment '847 Patent, abstract
• Technical Importance: The use of a polymer admixture provides a method to fine-tune the physical properties of the sanding block, offering a different technical pathway to achieve the desired balance of flexibility and firmness Compl. ¶12

Key Claims at a Glance

• The complaint asserts independent product claim 1 and independent method claim 6 Compl. ¶53
• Independent Claim 1 (Product Claim) requires:
  • An elastomeric sanding block conformable to curved or flat surfaces with a Shore A hardness of about 30 to 90;
  • Made from a composition comprising:
    • An admixture of about 70-90 wt% EVA copolymer and 10-30 wt% LDPE homopolymer, with this admixture comprising about 35-70 wt% of the total composition;
    • A blowing agent (about 1.5-4.5 wt%); and
    • A pigment (about 5-18 wt%).
• Independent Claim 6 (Method Claim) requires manufacturing steps that include:
  • Forming a composition by first forming the specified EVA/LDPE admixture and then combining it with a pigment;
  • Combining the overall composition with a blowing agent to yield a feedstock;
  • Thermoforming the feedstock; and
  • Cutting the resulting material.
• The complaint reserves the right to assert additional claims Compl. ¶53

U.S. Patent No. 11,292,103 - Hand-Held Conformable Sanding Block

• Patent Identification: U.S. Patent No. 11,292,103, "Hand-Held Conformable Sanding Block," issued on April 5, 2022 Compl. ¶16
• Technology Synopsis: This patent discloses a further-developed composition for a conformable sanding block, addressing the same technical problem of balancing rigidity and flexibility '103 Patent, col. 1:25-44 The solution presented is a more complex polymer blend, comprising an admixture of three components: EVA copolymer, LDPE homopolymer, and a metallocene catalyzed ethylene-α-olefin copolymer '103 Patent, abstract The claimed composition also requires a filler and a carbon pigment, allowing for more precise control over the block's physical properties like pliability and elasticity '103 Patent, col. 5:21-24
• Asserted Claims: The complaint asserts at least independent claim 1 Compl. ¶71
• Accused Features: The complaint alleges on information and belief that the accused sanding blocks are made from a composition that includes the three-part polymer admixture, filler, and carbon pigment recited in claim 1 Compl. ¶¶75-78

III. The Accused Instrumentality

Product Identification

• The accused products are identified as "Infringing Sanding Blocks" sold by or through Defendant Biologix, including under the "DROSO KING" brand on e-commerce sites like Amazon and eBay Compl. ¶¶18, 20-21

Functionality and Market Context

• The products are marketed as a "7PCS Sanding Block Kit" designed for sanding tasks on both "flat surfaces to curved edges" for materials such as car bodies, wood, and metal Compl. ¶39 Compl. ¶45 A screenshot of an online product listing for the accused product kit is described in the complaint as touting its flexibility for various sanding jobs Compl. ¶39 Compl. Ex. 5 at 1 The complaint also includes a representative image of Plaintiff's own "Dura-Block®" products, illustrating the general form factor of the technology at issue Compl. p. 3 The lawsuit alleges that Biologix operates through a network of affiliated entities and an individual, Xuelin Li, to market these products while attempting to avoid liability Compl. ¶¶19-29

IV. Analysis of Infringement Allegations

'403 Patent Infringement Allegations

Claim Element (from Independent Claim 6)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An elastomeric sanding block conformable to curved or flat surfaces	The accused product is marketed as a kit with "the flexibility to tackle a wide range of sanding tasks-from flat surfaces to curved edges."	¶39	col. 2:1-4
wherein the elastomeric sanding block has a Shore A hardness ranging from about 30 to about 90	The accused product is alleged to have a Shore A hardness of 46 ± 2.	¶40	col. 3:30-31
wherein the elastomeric sanding block is made from a composition comprising: a polymeric component, the polymeric component consisting of ethylene-vinyl acetate copolymer	The accused block is alleged to be made from a composition that includes ethylene-vinyl acetate copolymer.	¶41	col. 4:37-38
wherein ethylene-vinyl acetate copolymer is in an amount that ranges from about 35 to about 70 percent of the composition by weight	On information and belief, the percentage is within the claimed range, as a different amount would "materially impact the Infringing Sanding Block's physical properties, such that it would not be conformable to curved or flat surfaces."	¶42	col. 4:51-53
a blowing agent in an amount that ranges from about 1.5 to about 4.5 percent of the composition by weight	On information and belief, the composition includes a blowing agent within the claimed percentage range, as this is asserted to be necessary for foam products and for achieving the required physical properties.	¶43	col. 5:4-6

• Identified Points of Contention:
  • Evidentiary Question: The allegations concerning the specific weight percentages of the EVA copolymer and the blowing agent are pleaded "on information and belief" and are supported by a functional argument (i.e., the product would not work as advertised if the composition were outside the claimed ranges) Compl. ¶¶42-43 A central question for the court will be whether factual evidence obtained through discovery and expert testing substantiates these compositional claims.

'847 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
An elastomeric sanding block conformable to curved or flat surfaces, wherein the elastomeric sanding block has a Shore A hardness ranging from about 30 to about 90	The product is marketed for use on "flat surfaces to curved edges" and is alleged to have a Shore A hardness of 46 ± 2.	¶55; ¶56	col. 3:29-30
an admixture of about 70 to about 90 weight percent of an ethylene-vinyl acetate copolymer and about 10 to about 30 weight percent of a low-density polyethylene homopolymer, wherein the admixture is in an amount that ranges from about 35 to about 70 weight percent of the composition	On information and belief, the accused blocks comprise this specific admixture in the claimed amount, as percentages outside these ranges would allegedly prevent the product from being conformable and having the requisite hardness.	¶58	col. 4:7-13
a blowing agent in an amount that ranges from about 1.5 to about 4.5 weight percent of the composition	On information and belief, the blocks contain a blowing agent in the claimed amount, which is asserted to be a necessary component for such foam products to achieve their functional properties.	¶59	col. 5:4-6
a pigment in an amount of about 5 weight percent to about 18 weight percent of the composition	On information and belief, the blocks contain a pigment in the claimed amount, which is also asserted to be a necessary component.	¶60	col. 6:10-12

• Identified Points of Contention:
  • Evidentiary Question: As with the '403 Patent, all allegations regarding the chemical composition-including the ratio of polymers in the admixture, the total amount of the admixture, and the amounts of the blowing agent and pigment-are based on "information and belief" Compl. ¶¶58-60 The case will likely depend heavily on the results of chemical analysis of the accused products.

V. Key Claim Terms for Construction

• The Term: "about"

  • Context and Importance: This term qualifies every numerical range in the asserted claims (e.g., "about 30 to about 90," "about 35 to about 70 percent"). While the alleged hardness of the accused product (46 ± 2) falls comfortably within the claimed range, the exact chemical composition percentages are unknown Compl. ¶40 Practitioners may focus on this term because its construction will be dispositive if testing reveals the accused product's composition is near, but not identical to, the claimed endpoints.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patents do not explicitly define "about." A party arguing for a broader interpretation may assert that in the field of polymer science, the term accommodates normal manufacturing tolerances and slight variations that do not change the fundamental properties of the final product.
    • Evidence for a Narrower Interpretation: A party seeking a narrower construction may argue that the patentee chose specific numerical ranges to distinguish the invention from the prior art, as recited in the abstract and claims '403 Patent, abstract '847 Patent, abstract This suggests the endpoints are meaningful, and "about" should be interpreted narrowly to mean very close to the stated value, not as a license to significantly expand the range.

• The Term: "admixture"

  • Context and Importance: The '847 and '103 Patents are distinguished from the '403 Patent by the claiming of an "admixture" of multiple polymers, rather than a single polymer component. The definition of this term is therefore critical to determining infringement of the '847 and '103 Patents.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification of the '847 Patent describes the "admixture" as being composed of EVA and LDPE, and notes the sanding blocks are manufactured by "combining" the components '847 Patent, col. 3:9-12 '847 Patent, col. 4:50-54 This may support an interpretation that "admixture" simply means a physical blend of the constituent polymers.
    • Evidence for a Narrower Interpretation: The "Methods of producing sanding blocks" section describes a multi-step mixing and heating process to create the final product '847 Patent, col. 6:8-32 A party could argue that "admixture" implies a specific level of homogeneity or a particular state achieved through this disclosed process, and a simple or incomplete blend would not meet the limitation.

VI. Other Allegations

• Indirect Infringement: While the complaint's formal counts focus on direct infringement under 35 U.S.C. § 271, the prayer for relief seeks an injunction against both direct and indirect infringement Compl. p. 18, ¶E The factual allegations, however, do not specify actions taken by Defendant to encourage or contribute to infringement by third parties, focusing instead on Defendant's own acts of making, using, selling, and importing Compl. ¶18
• Willful Infringement: The complaint alleges willful infringement based on Defendant's continuation of infringing activities after receiving actual notice Compl. ¶50 This notice is alleged to have been provided via Amazon's APEX program on or around August 27, 2025, and September 23, 2025, which identified the '403 Patent and resulted in the takedown of Defendant's Amazon listings Compl. ¶¶30-34

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

• A primary issue will be one of evidentiary proof: Can Plaintiff, through discovery and expert testing, demonstrate that the accused sanding blocks contain the specific polymer compositions, including the precise weight percentage ranges, required by the asserted claims? The complaint's reliance on "information and belief" for these core technical limitations places the burden squarely on the factual record to be developed.
• A secondary issue may be one of claim scope: If chemical analysis shows the accused products have compositions near the boundaries of the claimed ranges, the litigation will turn on the court's construction of the term "about". How much deviation from the recited numbers is permissible will be a critical legal determination.
• A key procedural question will be one of liability: Can Plaintiff successfully "pierce the corporate veil" to hold the various alleged entities (Biologix, Constar, Novatek) and the individual (Xuelin Li) jointly and severally liable? The complaint's alter ego allegations suggest that proving this web of control will be central to ensuring any potential judgment is enforceable.