In Your Corner: Anthony Pajerski Examines the Present and Future of Water-Borne PUDs

Posted by Lubrizol Performance Coatings Team on 03/09/2020

Anthony D Pajerski, PhD, Technical Fellow in Lubrizol’s Performance Coatings business, has nearly 30 years of experience in the coatings industry, focused primarily on the chemistry of water-borne polyurethane dispersions. He has also helped commercialize other types of dispersions, such as plant-oil based acrylic dispersions. He has extensive experience in low temperature, water-borne, self-crosslinking, sustainable raw materials and urethane-acrylic composite chemistries. We spoke to Tony about his primary areas of work at Lubrizol and his areas of research interest.

“In Your Corner” is a series of interviews with Lubrizol ink and coating experts who share unique insights on key industry challenges and opportunities.

 

You work mostly with polyurethane dispersions (PUDs). Within this area, what is an important focus for you?

Most of my research interest centers in three areas: low or ambient/room temperature (RT) reactions for self-crosslinking, sustainable polymer compositions, and urethane-acrylic composite/hybrid polymer dispersions.

I have concentrated a lot of time and resources helping to develop low/RT self-crosslinking chemistry for water-borne polymers. I’m proud to have introduced auto-oxidative and carbonyl-hydrazide crosslinking chemistries to our PUD family at Lubrizol, including the use of exclusive raw materials.

 

What are some of the Lubrizol brands where these chemistries are used?

All of our Turboset™ PUDs and our Aptalon™ Polyamide Polyurethane technologies use self-crosslinking chemistry based on the carbonyl-hydrazide reaction (often referred to simply as Lubrizol Turboset™ technology). This works quite well for anionically stabilized water-borne dispersions as the reaction is triggered by a drop in pH and loss of water. A couple of examples of key products using this technology are Turboset™ Ultra Eco and Aptalon™ W8060.

For auto-oxidative crosslinkable products, Lubrizol has two options: Sancure™ OM933 and Sancure™ OM945. We have worked on expanding these options, but it has been challenging to match the performance of the Turboset™ chemistry. The main issues have been slower performance and hardness build versus the Turboset™ crosslinking technology. However, this approach naturally (no pun intended) uses more renewable raw materials through highly unsaturated plant oils, which provide an added degree of sustainability. While it has been challenging, the Sancure™ OM933 demonstrated excellent exterior durability by the Lubrizol Applications group, finding a place as a water-borne counterpart to its solvent-based exterior wood coating products. The plant oil-based polyol used in Sancure OM933 likely contributes to its exterior durability. That means further development of next generation exterior durable PUDs will likely see us turning to similar oil-based polyols as a starting point.

 

What has the impact of self-crosslinking chemistry been on Lubrizol’s ability to keep introducing innovative materials?

It’s had a significant impact. Several of our largest selling products utilize some form of self-crosslinking chemistry.  It has also made possible the introduction of products like Turboset™ Ultra Eco and Aptalon™ W8060 by allowing for technology to improve film formation. The result has been that Ultra Eco can be formulated to as low as 50g/L VOC and it allowed Aptalon™ film formation at RT where it previously required high temperatures to get a defect-free film. Of course, self-crosslinking chemistry also provides the performance required of a high-end floor finish. Without its contribution to our film forming technology, these products would most likely not have been possible—at least not with their current performance and hardness attributes. Looking ahead at potential future innovations where sustainability demands continue to be a driver, the most sustainable crosslinking chemistry is auto-oxidative. The use of itaconic acid (via formation of anhydride and subsequent reaction with alcohols or amines) is possibly even better, but the challenge so far has been applying in waterborne systems.  

 

The term “sustainable” is used a lot these days. How does sustainability impact your work at Lubrizol?  

It’s much more than a term. It’s exciting to be involved in developing sustainable chemistry that improves the efficiency with which natural resources are used. To date, I’ve been part of developing four products that have significant renewable content and great potential for future uses. These products focus on five sustainable areas:

 

  • Reduced VOC (this is a natural for water-borne, but still an issue for hard, higher performance polymers).
  • Renewable raw materials (as high as 50% in commercial plant oil derived products).
  • Good atom economy (making products with minimal or no waste reduces energy needs for disposal).
  • Processing time and conditions (energy) that are in line or lower than traditional products.
  • Durability (longer coating life, which can be further augmented by self-healing).

 

The first three areas are relatively easy to quantify, particularly the first two and are the ones everyone tends to focus on. The latter ones require significantly more information to quantify, particularly a coatings life cycle that would include its durability. A complete sustainability profile requires a life cycle analysis of a product that requires more than the above, such as understanding the energy used to create and deliver the raw materials used.

 

You said you’ve been part of developing four products that have high renewable content. What are those products?

Current products with significant renewable content based on plant oils are Carboset® AMO400, Carboset® 420, Sancure™ OM933, and Sancure™ OM945. However, we also have Carboset® 3076 which has our highest renewable raw material content, and most of our Aptalon™ products contain a portion of renewable content.  Turboset™ products also contain some renewable content but it’s a lower amount. In all our products, the renewable content contributes to the final products performance.

 

Apart from the future opportunities around sustainability, what other area do you think holds tremendous potential?

Aside from efforts in self-crosslinking chemistries, I have devoted a lot of time to the development of composite polymer (also termed hybrids) coatings at Lubrizol. The importance of this chemistry is illustrated in the growing number of products within Lubrizol Performance Coatings that are based on urethane-acrylic chemistry. Although it is primarily used as a process to obtain NMP-free polyurethane compositions, it also plays a significant role in the final performance of the polymer. For instance, it would be hard to imagine products like Turboset™ Ultra Eco and Aptalon™ 8060 without the use of urethane-acrylic chemistry. There are multiple ways that one can attain an NMP-free PUD. However, creative use of urethane-acrylic chemistry can contribute to improved performance, such as chemical resistance and a lower VOC product (as in Turboset™ Ultra Eco). PUD products that are NMP-free and have lower formulated VOC levels are trends that have been around for a while and have recently become even more urgent. Urethane-acrylics provide a path to that end, along with higher performance and better economics. Overall, it allows for improved sustainability.

 

Thinking about what’s important to industry formulators, is there one topic that really stands out? 

I think reduced VOCs would be it, particularly for performance applications like protective coatings. It is significantly easier to provide a low VOC coating formulation for a decorative coating such as wall paint. But it is a much more difficult proposition for a protective coating such as for a wood floor, which basically comes down to hitting performance requirements (which also include hardness). Hard water-borne coatings typically require a significant amount of coalescent (i.e., VOC) to form a good coherent film, whereas a soft coating could form a film without the aid of solvents.

 

Why does reducing VOCs in protective coatings stand out so much?

It is important for regions that are interested in protecting the environment and their citizens. Much of the work around VOCs involves government mandates for VOC reductions in order to be able to sell and use products in certain areas. For example, some VOCs can contribute significantly to smog and global warming, in some cases, more so than carbon dioxide on a per weight basis. Plus, greener chemistry is becoming more appealing to the general public, particularly in closed interior environments where VOCs can be trapped, creating greater exposure to it and any other toxins that might be carried by the product. The continued push for reduced VOCs is moving from California to other parts of the United States. Many of the European VOC regulations are in line with California. I think this will be a benefit to Lubrizol as we already have and are continuing to develop high performance, but low VOC products. 

Lubrizol Performance Coatings Team

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