Polyurethane mold release agents (PU)
Polyurethane mold release agents are chemical products applied to the mold to make it easier to remove the PU part and to protect the mold from the abrasion of the process. At AITANACHEM, we have developed a complete release system for this industry, based on high-performance water-based semi-permanent release agents. A single application allows multiple consecutive releases, with minimal transfer to the part and no build-up in the mold. They are suitable for both metal and polymer molds (epoxy, polyester, aluminium).
Why polyurethane needs a specific release agent
Polyurethane molding has a particular feature that sets it apart from other processes: the chemical reaction between the polyol and the isocyanate produces a highly reactive, abrasive mix that tends to bond strongly to the mold wall. A generic release agent breaks down quickly under these conditions. This is why a polyurethane release agent has to meet two demands at once — demands that also pull in opposite directions:
- Make the part easy to remove, providing non-stick properties and lubricity to the mold surface.
- Protect the mold from abrasion, forming a resistant physical barrier able to withstand the aggressiveness of the reactive mix cycle after cycle.
Our release agents are based on high-performance polymers that create precisely that flexible yet resistant barrier between the mold and the abrasive mix: lubricating enough for the part to release effortlessly, and tough enough not to break down with use.
The diversity of polyurethane: a release agent for each process
The polyurethane industry is one of the most varied there is, both in molding processes and in raw materials. Demolding a shoe sole is nothing like demolding an insulation panel or a dashboard. That is why we adapt the release agent to each type of PU and each production method:
- Rigid foam: insulation panels, technical insulation and lightweight structural parts.
- Flexible foam: seating, mattresses, cushioning and comfort applications.
- Integral skin: armrests, steering wheels, grab handles and parts with a compact surface and foamed core.
- RIM and RRIM: large technical parts produced by reaction injection molding, common in the automotive sector.
- Footwear and soles: where finish and clean demolding are critical to production throughput.
- Elastomers and compact PU: solid parts that demand a highly resistant release barrier.
What a polyurethane release agent must deliver
If you are evaluating suppliers for your PU process, these are the four criteria that make the difference:
Abrasion resistance
This is the requirement specific to polyurethane and the one most often overlooked. The physical barrier formed by the release agent must withstand the aggressiveness of the reactive mix without breaking down after each release. A release agent that resists abrasion maintains the number of cycles per application and, above all, protects the mold — the most expensive investment in your plant.
Minimal transfer to the part
The release agent must not transfer to or contaminate the molded part. This is especially critical for parts that will be painted, varnished or bonded at later stages, or for those with a high likelihood of self-release. Even minimal transfer forces you to add a washing step that increases costs and slows down the line.
Wax-free and no build-up in the mold
Traditional wax- and silicone-based release agents build up in the mold and force long, costly cleaning stoppages. Our semi-permanent release agents do not generate that build-up, which drastically reduces cleaning and maintenance times and keeps the mold productive for longer.
High number of releases per application
The strong anchoring of a semi-permanent release agent to the mold allows many consecutive releases after a single application, as opposed to traditional continuous-application systems that require reapplication on every cycle. This translates directly into higher productivity and lower product consumption.
Water-based release agents for polyurethane
At AITANACHEM, we encourage our customers to use water-based release agents. Developments in this technology over recent years have brought it on a par with solvent-based release agents in terms of performance, and its advantages make it increasingly sought-after in the PU industry: healthier and safer working environments, non-flammable behaviour, and lower transport and storage costs as it is not classified as dangerous goods (ADR). You can see the full comparison between technologies in our guide to mold release agents
Mold preparation and maintenance
The performance of any release agent depends on the condition of the mold. A mold with accumulated residue reduces the number of releases per application and worsens the finish of the part. Before implementing a semi-permanent system, we recommend that you:
- Carry out a thorough cleaning using mold cleaners suited to the type of residue.
- Apply a sealer as part of mold treatment and maintenance, which closes the micropores in the surface and multiplies the effectiveness of the release agent.
Frequently asked questions about polyurethane release agents
Why does polyurethane need an abrasion-resistant release agent?
Because the mix of polyol and isocyanate is highly reactive and aggressive towards the mold surface. If the barrier formed by the release agent does not resist that abrasion, it breaks down within a few cycles: the number of releases per application drops and the mold is left unprotected. A well-formulated polyurethane release agent combines lubricity to remove the part with the toughness needed to protect the mold cycle after cycle.
Can polyurethane parts be painted or bonded after demolding?
Yes, as long as the release agent does not transfer product to the part. Our semi-permanent release agents are formulated to prevent the transfer of silicones or oils, so the surface of the PU part is ready for painting, varnishing or bonding without an intermediate washing step. This is a decisive factor for automotive and decorative parts.
How many releases can you get from a single application?
It depends above all on the geometry of the part, the type of polyurethane and the process temperature, so we do not give a fixed figure: it would be misleading. The real difference lies in the technology: a semi-permanent release agent allows several consecutive releases after a single application, whereas traditional continuous-application systems require reapplication on every cycle. We determine the specific figure for your process during the trial phase at your premises.
Does the same release agent work for rigid foam, flexible foam and integral skin?
Not always. The wide variety of processes and raw materials in polyurethane means that a single product will not perform equally across all applications. That is why we adapt the release agent to each type of PU: flexible foam, rigid foam, integral skin and RIM have different requirements in terms of non-stick behaviour, gloss and release. We analyse your process before recommending a specific system.
How should a water-based release agent be applied correctly?
Application determines a large part of the performance. Water has a high surface tension, so spraying must be very fine to prevent product from accumulating and forming droplets on the mold; the technique involves several light passes rather than one thick coat. Applying more product does not guarantee better release — quite the opposite. We explain this step by step, video included, in our guide on how to apply water-based release agents
We adapt the release agent to your polyurethane process
The type of polyurethane, the molding method, the geometry of the part and the required finish completely change the requirements of the release system. That is why, rather than selling an off-the-shelf product, we have a highly qualified technical team that analyses your process and sends you the release agent that best fits your needs so that you can test it at your premises. Always with our technical support throughout the trial phase. Depending on the results, we assess adjusting the formulation to the specific characteristics of your production.
Are you experiencing mold abrasion, transfer to the part or residue build-up?
Get in touch with us and we will look at your case with no obligation.
👉 Looking for general information on release technologies, types of release agents and other application sectors? Take a look at our complete guide to industrial mold release agents