In the Polyurethane Segment, Temperature Control Has a Significant Impact on Production Performance and the Quality of the Final Product
In the polyurethane segment, temperature control significantly impacts production performance and the quality of the final product. In many cases, a lack of adequate temperature control can lead to financial losses and production delays for many companies. But how does temperature influence the characteristics of formulated PU raw materials and, consequently, production performance?
Below is the full article explaining how proper temperature control helps prevent serious issues during polyurethane processing.
What Happens to Formulated PU Raw Materials When They Are Cold?
Polyurethane systems are composed of reaction-aiding agents that accelerate chemical reactions. Proper temperature control enhances the physical and chemical behaviors of these reactions, improving the formation and curing of the final product and increasing production efficiency.
At lower temperatures, formulated PU raw materials become more viscous, making it harder to homogenize components in mixers, potentially causing mixing issues. In colder climates, materials become harder to mix.
A practical analogy would be mixing chocolate powder into milk: it’s much harder to get a good mix with cold milk, while the process is much easier with warm milk.
In PU products, chemical reactions slow down at lower temperatures due to reduced energy in polymer reactions. Conversely, at higher temperatures, reactions accelerate.
Each PU transformation segment typically requires a specific temperature range: it is recommended to control the temperature of the components, molds, and, in some cases, the ambient temperature where post-curing takes place.
Important Considerations
Temperature control must also extend to the storage conditions of PU system components, ensuring proper raw material preservation. It is recommended to store products on pallets, avoiding direct contact with the floor, as a significant range of these products is prone to crystallization.
Formulated Polyols
For formulated polyols (commonly known as component “A” of PU systems), certain polyester-based formulations are prone to crystallization at room temperature. These raw materials, typically used in the footwear industry, are usually melted in a water bath and processed at hot temperatures between 35°C and 45°C.
Polyether-based polyol systems are less prone to crystallization in cold temperatures. However, it’s worth noting that these formulated polyols can become highly viscous at temperatures below 15°C.
What About Isocyanates?
The most commonly used isocyanates include TDI (toluene di-isocyanate), MDI (diphenylmethane di-isocyanate), polymeric MDI, and modified MDI (carbodiimide).
Prepolymers made with these isocyanates—or blends of them—are susceptible to crystallization at temperatures below 15°C. Each specific blend varies in its resistance to cold, but none are immune to crystallization at lower temperatures.
How to Reverse Crystallization
Crystallized materials can be restored by placing them in a water bath at temperatures above 50°C. This process melts the crystallized material back to its liquid form, fully preserving its original properties.
Production Issues Related to Temperature
Without proper thermal protection, production problems can manifest in various ways, such as:
- Loss of block height
- Internal cracks in the block
- Longer demolding times
- Peeling (finish defects)
- Reduced resilience of parts
- Thicker skin layers
- Increased drying time
Other Solutions to Avoid Temperature-Related Problems
In addition to thermal control, attention must be given to equipment, including pipelines, tanks, and pumps. Depending on the PU injection machine, type of part, supply system, and storage system, the entire setup must have adequate thermal protection to prevent isocyanates from crystallizing within the supply line or pumps.
Thermal protection for chemical components, environments, and equipment is crucial to avoid downtime, production losses, and high costs.
Everyday Challenges
In the absence of thermal control, companies often restrict production to warmer times of the day, leaving production lines idle during colder periods. This practice negatively impacts productivity and efficiency.
Have you ever faced an issue where temperature control was critical for successful production?
Contact our Technical Support team for assistance with polyurethane processing and handling.
For more information about Amino Technology, contact us at +55 11 4077-3777 or email us at vendas@amino.com.br.
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