Nowe osiągnięcia w technologii klejów akrylowych następnej generacji.

INTRODUCTION

Structural acrylic adhesives are two-component systems (adhesive plus accelerator) that provide bonding strength equal to or exceeding the strength of the substrate. Significant commercial use of acrylic adhesives began in the 1960s. "First-generation systems" were brittle and typically used for bonding plastics. They usually contained poly(methyl methacrylate) dissolved in methyl methacrylate ("syrup") and a "lacquer" accelerator used in a high mixing ratio.

"Second-generation structural adhesives" provided effective bonding performance in various commercial applications for the past 30 or more years. These systems were more durable and offered improved performance at low temperatures and better bonding with metals. They contained butadiene rubber reinforcements, metal adhesion promoters, and mixing ratios of 1:1 and 4:1 with accelerators.

"Next-generation acrylic adhesives" have evolved in recent years to provide increased performance in more demanding applications. Key features of "next-generation adhesives" include advanced core-shell rubber reinforcements, polymerizable monomer blends, and a 10:1 mixing ratio. Enhanced performance features include:

• High tensile shear strength - targeting structural applications
• Improved peel strength - better performance in mixed stress applications
• Excellent damage mode on a wide range of substrates - more resilient performance increasing usability for many applications
• High impact resistance - suitable for use in tough conditions where impacts may occur
• Improved fatigue resistance - performs better under cyclic stresses or vibrations
• Excellent performance at low temperatures - important for use in challenging climatic conditions
• Electrophoretic and paint bake resistance - bonded parts will not shift/separate during baking
• REACH compliant formula (Europe) - elimination of toxic components enables global use

ENHANCED PERFORMANCE

It's worth comparing "structural acrylic adhesives" such as LORD 852/25GB with some of the most commercially successful examples of "second-generation acrylic adhesives." One significant difference in physical properties is a significant increase in elongation (100 percent compared to 35 percent) for "next-generation acrylic adhesive," while maintaining the same high tensile strength (about 18 MPa for both). This increase in elongation without loss of tensile strength is key to many elements of improved performance of "next-generation acrylic adhesives." Another element of improved performance of "next-generation acrylic adhesives," which is most visible to manufacturers, is excellent damage mode and performance on various, difficult-to-bond metal substrates.

Figure 1 and Figure 2 show comparisons of tensile shear strength and T-peel strength for "second-generation acrylic adhesive" and LORD 852/25GB. Tensile shear strength primarily reflects the adhesive's tensile strength, while good peel strength performance requires higher strength and elongation. The bonding results show equivalent tensile shear strength, while the more flexible "next-generation acrylic adhesive" demonstrates a significant improvement in T-peel strength. It is also worth noting a significant improvement in damage mode using "next-generation acrylic adhesive."

Shear Resistance Test (Metal Bonding)

Figure 1

APPLICATION: MOUNTING WIND TURBINE TOWERS In this application, the acrylic adhesive LORD 852/25GB "next generation" was qualified for use in the construction of wind turbine towers. Due to its excellent damage mode on difficult-to-bond substrates, the adhesive proved ideal even for hybrid bonding - aluminum to hot-dip galvanized steel sheet - necessary for the production of wind turbine tower enclosures. Figure 10 illustrates the application of mounting wind turbine towers. Figure 10: The wind tower assembly design required the use of an adhesive that would provide good damage and material fatigue resistance. Application: Wind Tower Assembly Bonding hot-dip galvanized steel and aluminum Large parts with varying line thicknesses of adhesive Key Performance Requirements: Good damage and material fatigue resistance  CONCLUSION The evolution of acrylic adhesives to next-generation formulations has significantly expanded their capabilities, making them suitable for a wide range of demanding applications in various industries. The LORD 852/25GB adhesive exemplifies this advancement, offering superior performance in terms of bonding strength, impact resistance, environmental durability, and ease of application. Whether in the automotive, construction, or renewable energy sectors, the versatility and reliability of next-generation acrylic adhesives make them a preferred choice for manufacturers seeking efficient, cost-effective, and durable bonding solutions.