Few things seem simpler than bonding two materials. Yet, from a label on a bottle to the compounds holding an aircraft together at 10,000 meters, adhesives are the silent enablers of modern life. Designed to bond substrates as varied as metal, glass, or plastic, they are essential across countless industries.

In a world where lightness, flexibility, and strength are key drivers of innovation, polyurethane adhesives have evolved from supporting roles to critical enablers. Their application spans automotive manufacturing, technical footwear, performance furniture, advanced textiles, and a wide range of industrial uses. Their proven reliability and versatility have made them a trusted choice for years.

Advanced Solutions for Demanding Formulations

Lubrizol offers an extensive portfolio of thermoplastic polyurethanes (TPUs) designed for adhesive formulations tailored to a broad array of markets and performance requirements. With over 65 years of TPU innovation, Lubrizol has been helping customers with their needs with an emphasis on quality, performance, and sustainable innovation. 

Through decades of innovation and strong dedication to the adhesive industry, we have developed one of the deepest, most specialized portfolios available. The Pearlbond™ and Pearlstick™ TPU low and high melting point product offerings uniquely positions Lubrizol to satisfy customers' melting range needs across a wide crystallization range. Pearlstick TPU is Lubrizol's product series for solvent-based adhesives, inks, binders, lacquers, and other uses, which has been engineered for solubility in a wide range of organic solvents with varying evaporation rates. This enables formulators to fine-tune the solvent system to match the application process, optimizing either process speed or the final film's quality. Key benefits include:

• High green strength
• Low thermal activation temperature
• Excellent adhesion to polar substrates
• High flexibility at low temperatures
• Good thermal resistance

Where enhanced performance is required, Pearlstick TPU adhesives can also be formulated with fully compatible crosslinking agents to increase final bond strength and thermal resistance.

The range includes grades with extended open times, allowing use in contact adhesive formulations while delivering significantly higher final adhesion values compared to standard solutions (in accordance with the test performed on PVC at these conditions: 16 seconds at 1.5 Bar of pressure).

Examples where Pearlstick TPU is widely used include:

• Technical textile priming, where it enhances the bond between the fabric and a TPU coating layer. In this application, both Pearlstick 46-10/01 TPU or Pearlstick 5703 TPU have demonstrated excellent performance and durability. 
• Footwear assembly, where it provides strong adhesion between leather uppers and linings or between soles and uppers. Pearlstick 40-70 TPU with its fast crystallization rate or Pearlstick 45-60 TPU series with its high tack at low temperatures, are well-established for their proven performance.
• Automotive interiors, where an adhesive with very high green strength and long open times is needed, allowing its use without reactivation and providing excellent final adhesion. Pearlstick 45-90 series has been present in this market for many years.

Hot Melt Adhesive Innovation

Lubrizol also offers the solvent-free Pearlbond TPU series, developed for both reactive (HMPUR or RHM) and non-reactive hot melt adhesive (HMA) formulations. These materials offer:

• Low to medium melting temperatures
• High thermoplasticity and fast crystallization rates — ideal for thermobonding applications
• Grades with very low hardness, high elasticity, and transparency.

These features make Pearlbond TPU extremely versatile, suitable for powder, film, roller or rotogravure coatings, and even melt-blown web structures.

In line with the goal of offering more versatile adhesives with enhanced performance, Lubrizol’s innovation technical experts are actively developing new soft and plasticizer-free materials. The most recent developments enhance color stability, like Pearlbond 920L and Pearlbond 960 TPUs. Both are aliphatic in nature, which provides outstanding resistance to external environmental conditions without yellowing or loss of properties. Each of these grades offers distinct characteristics and are highly valued across the textile, automotive, and even furniture industries.

Pearlbond TPU grades specifically developed for hot melt polyurethane reactive (HMPUR) systems offer:

• Shorter setting time 
• Significant improvement in green strength
• Full compatibility with polyesters commonly used in reactive formulations

Pearlbond 502 TPU is one of the leading resins in this field. It has been used for decades improving the performance of many HMPUR formulations, especially in those used for profiles, edge-banding, or woodworking in general. 

Commitment to Sustainability

Lubrizol's commitment to sustainability is also reflected in its adhesive solutions. Options include products based on renewable feedstocks (Pearlbond ECO TPU) and mass-balance TPU resins (Pearlbond RNW TPU), designed to reduce the carbon footprint without sacrificing performance. 

As examples, Pearlbond ECO 590 TPU with extremely fast crystallization and very low melting temperatures, contains 67%* of renewable carbon in its structure allowing the reduction of carbon footprint in HMPUR or thermobonding. Pearlbond ECO 590HMS TPU has been especially modified to provide high extrusion stability, excellent adhesion to wood, MDF, ABS, or many other substrates. 

Lubrizol's TPU for adhesives has become more specialized and sustainable in the last decades, aligning with evolving market trends and sophisticated processing demands. Lubrizol leverages its extensive expertise to advance adhesive innovations, focusing on creating adhesive solutions, including solvent-free options, which cater to modern material needs. 

By refining TPU formulations, Lubrizol can enhance the end product’s performance, durability, and environmental footprint. This commitment to sustainability and specialization not only meets current market demands but also positions Lubrizol as a leader in adhesive science, continuously pushing the boundaries with its decades-long knowledge and experience in the industry. 

To learn more about TPU for adhesives, visit Lubrizol's website at www.lubrizol.com.

*Bio-based content certified according to ASTM D6866

Article images are supplied courtesy of Lubrizol.