We are proud to share that our R&D technician, Adrià Lopez, has published an article in Urethanes Technology magazine. This recognition reflects our team’s commitment to innovation and applied research in the polyurethane sector. Adrià’s work offers fresh perspectives on the development of sustainable foams, highlighting our ongoing efforts to combine advanced technology with responsible and efficient solutions.

Performance Optimization in Water-Blown Polyurethane Foams: Benchmarking Surfactants for Spray Foam Application

Introduction

The transition to a more sustainable and safer technology in the polyurethane industry, and specifically in the construction sector, has driven the development of water-blown systems, especially in spray foam applications. The phase-out of blowing agents with high global warming potential, such as HCFCs and HFCs, requires formulations that maintain high technical performance without compromising stability, expansion and of course processability.

In this context, silicone surfactant plays a crucial role in foam formation and stabilization, directly impacting foam kinetics, cell morphology, and final density. In turn, a thin and uniform cell structure contributes to improving thermal insulation (lambda value), a key aspect in terms of sustainability, since lower thermal conductivity translates into greater energy efficiency in buildings and, therefore, a reduction in energy consumption for air conditioning.

Therefore, the choice of a suitable silicone surfactant is decisive to ensure good expansion, low thermal conductivity, a homogeneous structure and adequate stability, both in initial conditions and after aging during storage.

This study presents a comparative evaluation of five surfactants applied to a water-blown formulation with water-based blowing agent, analysing key parameters such as foaming time, expansion time, stability and density. In the initial conditions and also applying an aging test at 40ºC and 3ºC for 5 weeks.

With the aim of identifying the most robust and stable references for their possible application in industrial systems of high-efficiency sprayed foam, aimed at formulators looking for sustainable solutions without compromising technical quality.

Methodology

Six references were evaluated: PU-2216, PU-2211, PU-2208, PU-2208 D, PU-2267 and PU-2217

In two standard formulations of rigid water-blown foam, at a density of 10Kg/m3 and 14Kg/m3. With a silicone surfactant content ≈2.2pphp. The tests were carried out under controlled conditions at 25ºC.

The 5-week aging test at two temperatures (40ºC and 3ºC), evaluating the impact of storage on foaming properties.

Results

In Board 1 the performance of the different references under initial conditions is summarized.

The results obtained show notable differences between the references evaluated. Among them, PU-2267 is positioned as the most balanced choice in terms of overall performance; with a low and controlled density, ideal for achieving good thermal efficiency without compromising the structure. Presenting expansion and foaming times within the optimal range. The best performance of the set with a height of 350mm that reflects an excellent capacity for expansion and stabilization and highlighting a homogeneous and closed cell morphology, without signs of collapse.

In comparison, PU-2208 and PU-2216 offered acceptable behaviour, although with slightly higher densities and lower height reached. PU-2208D showed a trend towards lower structural stability, and PU-2211 presented insufficient results, with clear signs of instability in the foam, so it was discarded for later tests.

Aging test

The results show a change in the critical parameters of the different references. The PU-2267 once again stood out as the most robust reference, with results practically unchanged. A stable density, consistent reaction times and high expansion were maintained, confirming its excellent resistance to deterioration.

The results once again highlight PU-2267 as the most robust reference both in initial conditions and after the aging test.

Conclusions

The study highlights the relevance of an adequate selection of surfactant to guarantee performance and stability in low-density water-blown  spray systems applied in construction.

Among all the references evaluated, PU-2216 showed a solid technical profile, being a valid reference in formulations where flexibility is sought without compromising stability. However, PU-2267 is positioned as the most balanced and robust option, with excellent performance both in initial conditions and after thermal aging, and in low and medium density formulations (≈10 and 14 kg/m³). Its consistent performance makes it an ideal candidate for demanding industrial applications.

The full article can be accessed in Urethanes Technology: https://www.utech-polyurethane.com/information/shifting-greener-agents