Binder Compositions for Enhancing Strength and Reducing Costs in Cold-Pressed Engineered Wood Products

Background

Engineered wood products, such as plywood, particle board, and laminated timber, are widely used in construction and furniture manufacturing due to their versatility, resource efficiency, and ability to utilize lower-grade wood materials. The performance and durability of these products heavily depend on the binders or adhesives used to bond wood fibers, strands, or veneers together. Traditionally, synthetic adhesives—especially emulsion polymer isocyanate (EPI) resins—are favored for their strong bonding capabilities and compatibility with cold-press manufacturing processes, which cure adhesives at room temperature. However, the high cost of these synthetic binders significantly impacts the overall production expenses. As a result, there is a persistent demand for more economical binder solutions that do not compromise the structural integrity or performance of engineered wood products, particularly as the industry seeks to expand the use of mass timber and other advanced wood composites.

Despite ongoing efforts to reduce costs and improve sustainability, current approaches to binder formulation face notable challenges. Attempts to partially or fully substitute synthetic adhesives with less expensive, renewable alternatives—such as animal, milk, or vegetable proteins—have generally failed, as these substitutes often result in poor adhesive performance, especially in terms of strength and moisture resistance. Additionally, the widespread use of preservative treatments, like copper azole, to protect wood from biological degradation can exacerbate bonding issues; these treatments increase the wettability of wood, causing adhesives to over-penetrate and weaken the bond. Existing cold-set resins may also require long pressing times to achieve adequate strength, further limiting production efficiency. Thus, the industry continues to seek binder technologies that are both cost-effective and compatible with preservative-treated wood, while maintaining or enhancing the mechanical properties and processing efficiency of engineered wood products.

Technology

This technology is a binder system designed for cold-pressed engineered wood products, utilizing a blend of soy-based materials (such as soy flour, meal, or isolate) and an emulsion polymer isocyanate (EPI) adhesive. The binder typically contains 5–50% soy product by weight and is applied to lignocellulosic materials, including those pre-treated with copper-based preservatives like copper azole. The process involves mixing the soy product—either dry or as a water suspension—with the EPI adhesive, optionally adding functional additives such as dyes or fillers, and then applying the mixture to wood components. These components are pressed at room temperature to form a variety of engineered wood products, including glulam, cross-laminated timber (CLT), laminated veneer lumber (LVL), and mass timber. The binder system is compatible with existing industrial adhesives and processes, and can be tailored for specific performance requirements.

What differentiates this technology is its ability to significantly enhance the dry shear strength of engineered wood composites while maintaining or improving wet strength, even when a substantial portion of the synthetic adhesive is replaced with an inexpensive, unmodified soy product. This results in lower material costs due to reduced reliance on costly synthetic resins and faster production cycles thanks to shorter pressing times. The binder’s compatibility with copper-based wood preservatives further increases its utility, as it reinforces adhesive bonds in treated wood, which is often challenging for conventional adhesives. Additionally, the system does not require chemical modification of the soy component, simplifying manufacturing and reducing environmental impact. This combination of cost savings, improved mechanical performance, process efficiency, and sustainability makes the technology a compelling solution for the engineered wood industry.

Benefits

• Increased dry shear strength of engineered wood composites
• Maintains or improves wet strength of wood products
• Reduces the amount of synthetic adhesive required, lowering material costs
• Enables shorter pressing times, improving production efficiency
• Compatible with cold-press processing at room temperature
• Works effectively with copper-based preservative-treated wood
• Uses unmodified, cost-effective soy products as partial resin substitutes
• Applicable to a wide range of engineered wood products (glulam, CLT, LVL, mass timber)

Applications

• Mass timber construction materials
• Cold-pressed plywood manufacturing
• Engineered wood flooring production
• Edge-bonded structural columns
• Laminated veneer lumber (LVL) panels

Additional info

These compositions and methods describe a binder for cold-pressed engineered wood products. It combines a soy product (5-50 wt.%) with an emulsion polymer isocyanate adhesive. Applied to lignocellulosic material, often pre-treated, and pressed at room temperature, it enhances dry shear strength, maintains wet strength, reduces synthetic adhesive use, and shortens pressing times for composites like glulam and CLT.