Wanhua Chemical's low-viscosity aliphatic polyisocyanates for low-VOC polyurethane coatings
Last update on Feb 19, 2025
An Interview with Eric Oude Spraakste, Technical Manager for Coatings at Wanhua Chemical (Europe)
The coatings industry is undergoing a significant transformation, with a stronger focus on high-performance solutions that prioritize environmental sustainability.
Polyurethane coatings commonly used to protect surfaces in industrial, commercial, and residential settings are evolving to minimize their environmental impact without compromising efficiency or durability.
These coatings, alongside next-generation paints, are at the forefront of a movement aimed at reducing carbon footprint and cutting volatile organic compound (VOC) emissions.
Aligning with these developments, Wanhua Chemical has developed the groundbreaking low-viscosity WANNATE® HT-plus series. This series demonstrates how modern coating solutions can help achieve superior durability while supporting sustainability goals.
We interviewed Eric Oude Spraakste, Technical Manager for Coatings at Wanhua Chemical (Europe). He provides insights on how selecting the right polyisocyanates will help reduce carbon emissions, minimize VOCs, and thus contribute to a more sustainable coatings industry.
#1. What does "reducing carbon footprint" mean?
The term "carbon footprint" refers to the total greenhouse gas emissions — measured in CO2 equivalent — produced directly or indirectly by a product, process, or activity over its lifecycle. For polyurethane coatings and paints, this includes emissions from raw material production, manufacturing, application, and disposal or recycling.
Reducing the carbon footprint involves adopting solutions and technologies that minimize these emissions, contributing to climate change mitigation and a more sustainable production model.
The role of VOC reduction
VOCs have traditionally been a concern in coatings and paints due to their detrimental effects on air quality, contributing to (indoor) pollution and posing health risks. The latest polyurethane coatings use advanced technologies to offer low-VOC or even VOC-free alternatives. This is particularly beneficial in enclosed or high-traffic environments where air quality is crucial.
Durability and sustainability in coatings
Sustainably coated surfaces not only enhance environmental performance but also provide practical benefits. Coatings with superior resistance to wear, scratches, and chemicals reduce the need for frequent repairs or replacements. This extends the lifespan of surfaces, lowers cost, and decreases emissions associated with maintenance.
Similarly, the paint industry is embracing innovation. Low-impact formulations are now being used to create high-quality finishes that offer long-lasting protection. Water-based paints, for example, are increasingly popular due to their combination of performance and sustainability.
Minimizing VOCs and carbon emissions
Reducing VOCs and carbon emissions in coating formulations is closely tied to lowering solvent content and enhancing durability. By decreasing the use of thinners, not only can VOC emissions be reduced, but CO2 emissions associated with the production and transport of solvents are also minimized. Furthermore, coatings that last longer help preserve products, reducing the need for replacements and repairs. This reduces resource consumption and energy use over a product's lifecycle.
#2. How does Wanhua contribute to sustainable innovation?
Wanhua, a global leader in aliphatic polyisocyanate production, has introduced a revolutionary range of low-viscosity products designed to optimize polyurethane coating formulations. These innovations meet the increasing demand for environmentally responsible solutions and offer businesses the opportunity to stand out in a competitive market. By delivering products that align with sustainability goals, Wanhua is helping the coating industry transition to a more sustainable future.
Wanhua's product range and features
The chart below shows Wanhua's range of products, including several 100% solid content grades with varying viscosities.
| Product | Viscosity (mPa.s) | Residual Monomer | Features |
| WANNATE® HT-100plus | 2500 | ✓ | Industry standard HDI trimer |
| WANNATE® HT-600plus | 1250 | ✓ | Low-viscosity HDI trimer |
| WANNATE® HT-3100plus | 800 | ✓ | Ultra-low viscosity HDI trimer |
| WANNATE® HT-300plus | 450 | ✓ | Ultra-low viscosity HDI flexible allophanate |
Table 1: Wanhua's product range with varying viscosities and features
Wanhua's low-viscosity products allow for the formulation of high-solid coatings, achieving the desired viscosity without the need for excessive solvents. This is illustrated in Figure 1.
Figure 1: Wanhua's low-viscosity products allow the formulation of high-solid coatings
#3. How to select the right polyisocyanate?
Choosing the right polyisocyanate for a specific formulation involves considering performance factors like:
- hardness development,
- pot-life,
- chemical resistance, and
- compatibility with binders and pigments
Graphs below demonstrate how Wannate® HT-100plus sets the market standard in terms of balanced performance. WANNATE® HT-600plus and WANNATE® HT-3100plus offer nearly identical performance, with the main difference being the desired viscosity.
Figure 2: Impact of WANNATE® Grades on Chemical Resistance, Hardness, and Pot Life of Paints and Coatings
In particular, WANNATE® HT-3100plus represents a breakthrough, offering the same performance as a standard HDI trimer but with a viscosity three times lower and an excellent shelf life (see Figure 2).
WANNATE® HT-300plus offers extended pot-life and exceptional mechanical flexibility, making it ideal as a co-hardener in systems like polyaspartics and high-resistance soft-touch clearcoats. Additionally, its compatibility with binders and pigments surpasses other WANNATE® grades, providing greater formulation and application freedom (see Figure 3).
Figure 3: Benefits of WANNATE® HT-300plus
About Wanhua Chemical
Wanhua Chemical is a leading global provider of polyurethane products, including isocyanates and polyols, along with petrochemicals and functional materials. With 27,000 employees and a revenue of $25 billion in 2023, Wanhua operates across 27 countries, with 10 production sites and 14 laboratories.
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DISCLAIMER: All images, tables, and graphs used in this article are copyright of Wanhua Chemical.