Concentrol is a chemical solutions company with the aim of providing references to streamline the production processes of professionals working in various sectors.
The release agents offered by Concentrol have been developed after years of research and experience gained in sectors such as automotive, footwear, furniture, construction, and others.
Molded polyurethane parts are essential in the vast majority of the aforementioned sectors, and their use is constantly expanding. These components play a fundamental role in the production of advanced polymeric materials. Different applications can be grouped according to the type of foam and the type of process, resulting in the following divisions: hot-curing flexible foam; cold-curing flexible foam; integral skin flexible, rigid, and semi-rigid foam; R.I.M. rigid, semi-rigid foam; and elastomers.
In the following Research Blog, we will explain what rigid polyurethane foam release agents are and their characteristics, focusing especially on two key sectors: insulation and automotive.
Release Agents for Rigid Foam: What Are They For?
Release agents for rigid polyurethane foam are chemical agents designed to facilitate the demolding process during the production of rigid foams. These foams, known for their exceptional insulating properties, are used in a wide range of applications, from construction to the manufacturing of components for the automotive industry.
In the insulation sector, where energy efficiency and sustainability are crucial, release agents for rigid foam play an important role. They facilitate the smooth and precise demolding of polyurethane foams, allowing the creation of highly efficient insulation products. From panels to thermal insulation systems, these release agents contribute to the creation of more energy-efficient structures, improving the quality of life and reducing the environmental footprint.
In the automotive sector, where the constant search for lighter and stronger components is a priority, release agents for rigid foam also play an essential role. By facilitating the production of structural and insulating parts, these compounds contribute to the creation of vehicles that are more efficient in terms of weight and performance. From seats to interior panels, the application of release agents in the manufacturing of automotive components drives innovation and sustainability in the industry.
Types of Release Agents for Rigid Polyurethane
Rigid polyurethane is a material with a significant function as a thermal insulator. Its low thermal conductivity is due to its closed-cell structure, a feature that allows energy savings through thermal insulation. There are different release agents for rigid polyurethane, including:
- Solvent-based release agent for rigid polyurethane
- Water-based release agent for rigid polyurethane
- Concentrated water-based release agent for dilution
- Concentrated solvent-based release agent for dilution
- Paste release agent for rigid polyurethane with a solvent base
The parts obtained through demolding with rigid foam are mainly continuous and discontinuous insulation panels, as well as insulation parts for automobiles and external decorative parts such as spoilers. Other imitation wood pieces for decoration or furniture can also be created.
The molds that lead to these parts can be made of aluminum, wood, stainless steel, or epoxy resin. In foam demolding facilities, for sectors such as automotive or furniture, they often use molds made of steel and/or aluminum, while in countries or sectors with limited technology or more relaxed acceptance and quality standards, materials such as epoxy resin and wood can be used. It is important to note that, in the production of demolded rigid foam with a water-based or hybrid product, if the solution comes into contact with ferrous surfaces, signs of oxidation may appear in the short or medium term.
Industrial Installations Using Rigid Foam
Facilities employing rigid foam typically include carousels for small parts, static molds, or continuous production systems such as slabstock.
Insulation Sandwich Panels:
Sandwich panels consist of an insulating core of rigid polyurethane or polyisocyanurate (PUR-PIR) foam adhered to two surfaces, usually metallic, with the metal layers commonly being steel or aluminum.
During the manufacturing process, the covering layers are prepared by profiling them according to the desired initial shape. Once shaped to meet the requirements of each panel type, they are transported to the press, where the mixing head injects the necessary components with a predetermined dosage, forming the foam in liquid phase. Its chemical reaction causes the foam to expand, adhering to the two covering layers, the bottom, and the top. With the application of heat and pressure for a specified time until curing, we obtain what is known as dimensional stability of the core.
The release agent is applied beforehand to the sides of the press, where there will be direct contact between the rigid foam and the mold.
Applications of PUR/PIR Sandwich Panels:
The field of application for PUR-PIR sandwich panels is very similar, as they can be applied to facades, roofs, false ceilings, interior partitions, and refrigeration chambers. Specifically, they are used for:
- Thermal insulation for the construction of refrigerated trucks.
- Thermal insulation for the floors of refrigeration chambers and freezing tunnels.
- Thermal insulation in sandwich panels with metal sheet, polyester, wood, fiber cement, etc.
- Working temperature range: temperatures below 0 °C to 80 °C.
- Support for pipes and pumps, machined in the form of half-shells.
- Industrial buildings, airports, administrative buildings, booths and prefabricated houses, hotels, exhibition halls and trade fair venues, laboratories, clean rooms and operating rooms, paint rooms, power plants, recycling plants, and waste incineration plants, sports facilities, large commercial surfaces, roofs, and facades of houses, preservation rooms, process rooms, etc.
Advantages and disadvantages of using rigid foam
The use of rigid foam results in pieces with a dry finish and a surface that can range from closed pores to completely open. The final piece can also have different densities, depending on the purpose and the customer’s process.
The main benefits of using rigid foam are:
- Acoustic absorption properties: Helps eliminate annoying noises both externally and internally. Polyurethane is an excellent acoustic insulator.
- Moisture elimination: Rigid polyurethane achieves continuous insulation in the area to be rehabilitated. Thanks to its waterproof characteristics, polyurethane foam can prevent moisture from entering while allowing microscopic breathing, preventing the accumulation of microorganisms and fungi.
- Sealing layer: Polyurethane creates a sealing layer that prevents cracks and potential air or water leaks.
- Thermal performance and cell structure: Polyurethane provides maximum insulation with minimal thickness, thanks to its thermal performance and cell structure.
The use of rigid foam also presents some challenges:
- Mold temperatures can be very low.
- Large or cavity-filled parts can be rigid to demold.
- The subsequent cleaning and painting process should not be excessively affected by the release agent, or it may be necessary for the demolded parts to be paintable without degreasing. In some cases, it is necessary to work with silicone-free release agents to avoid their anti-adherence and contaminating effects, as even a small amount can cause painting problems, wetting defects, and paint adhesion issues on the surface. Several procedures ensure painting and high adhesion, but in this sector, it is common to undergo mechanical polishing before painting.
Application Systems
The application systems will depend on the type of products used:
- Products classified as class 1, meaning ready-to-use and with a flashpoint below 21°C, can be applied without problems using airless equipment, as they do not require air assistance for the drying of the film on the mold.
- Class 2 products have slower drying, and therefore, it is advisable and essential to use drying equipment for 1 to 1.5 minutes, with the mold between 50 and 70 °C.
The sizes of the filters to be used are conditioned by the size of the pieces to be demolded and the time available to apply the release agent to all corners of the mold. Generally, we can talk about sizes of 0.5 mm for standard pieces and 1.2 to 1.5 mm for large pieces.
Regarding the use of airbrush or air-mix equipment, airbrush equipment is comfortable to use, especially Shütze brand guns, which are small in size and lightweight. These have product pressure and air pressure, which regulates the spray.
Air-mix equipment is more effective in robotic release agent application, where more movement and fan shape variations are needed to reach the entire mold without complex travel programming. They have more than one additional air outlet, which helps regulate the three-dimensional shape of the fan to conical spray.
The airless applicator only has air pressure to propel the product, and with the help of the shape and dimensions of the filter, it is necessary to find the best fan. It does not aid in drying, so in many applications, it is not useful.
Mold Cleaning
After demolding the pieces, other processes such as painting will take place, during which the piece is usually polished to remove any residue from the release agent.
Mold cleaning will depend on the residue left in the mold after work cycles, varying according to the type of polyurethane pieces being molded, the PUR system, and the type of release agent. However, it is important to consider that interaction with the components is always present, to a greater or lesser extent.
Only release agents that leave a soft residue can be cleaned with liquid products, while others allow variations depending on each chain and customer.
- Wax Melting: Wax is melted onto the mold using temperature, and additional infrared light or a blower may be applied as reinforcement. Once melted, it is removed with a clean cloth, repeating if necessary.
- Cold Mold and Chipping: The mold is allowed to cool at room temperature. Since the wax is hard, it tends to break off with the help of a scraper, and the entire layer can be removed.
- Cryogenic Method: The mold is impregnated with dry ice gel as an abrasive, obtaining a new mold. Before foaming, it is necessary to apply several layers of release agent or reinforcing paste. This system is especially necessary with water-based release agents since, along with wax residues and the active ingredient of the release agent, polyureas resulting from the interaction of unevaporated water residues with isocyanate accumulate, leading to an infusible material. The cryogenic system is based on the projection of dry ice (carbon dioxide) onto the mold surface using high-pressure compressed air. The projection of these pellets, which could also be made from walnut shells or similar materials, creates a thermal contrast that, along with the impact of the projection, causes surface residue to jump off. After the impact, these dry ice pellets sublimate into a gaseous state and, along with the induced air current, convert the dirt into macro particles.
- Cleaner: Suitable for soft residues such as waxes, resins, oils, or silicones, among others.
- Abrasive Method: Similar to the cryogenic method, but less aggressive. In this case, instead of dry ice, sand, walnut shells, or baking soda, among others, are used.
Concentrol references
The CONCENTROL® range provides specific and efficient solutions for all types of polyurethane panels, including those with increasing demands regarding surface finish, high productivity, cost, mold cleanliness, easy application, and the protection of the work environment and the environment.
The product range is extensive, offering release agents based on solvents and water, concentrates, and dilutable concentrates. Additionally, customized solutions can be designed according to customer needs.
New Developments
Concentrol’s R&D department is considering launching two new products:
- CONCENTROL LX RP-3-01: High performance release paste. It is a paste product, ready to use or to be diluted with aliphatic hydrocarbons from 1:1 to 1:4. The finish of the piece is slightly greasy and has excellent release capacity, even in difficult areas. It is applied by brush or broom, and with a single application it can provide 3 to 6 releases.
- CONCENTROL LP PFA-132 V: Water-based paste for general rigidity. It can be used at a working temperature between 45 and 65 °C. Application is by brush and serves as a reinforcement for water-based release agents in difficult areas.
Complementary Additive Products
Concentrol also offers a series of additive references that can complement these processes:
- ADDITIVE CTDC: Foam hardener that improves demolding.
- ADDITIVE ESFCJ: Surface film former for foam that helps close pores and prevents surface collapses.
- ADDITIVE-14: Less active surface film former for foam that provides a lubricating effect during demolding.
- ADDITIVE NK: Water-based foam hardener to enhance demolding.
- ADDITIVE NK-2: Water-based and DBTDL-free foam hardener to improve demolding.
- ADDITIVE ESFW: Water-based surface film former for foam that closes pores and prevents surface collapses.
Concentrol can supply products to all sectors with traditional solvent-based release agents, concentrates, dilutable concentrates, hybrids, and water-based options. Concentrol’s range of release agents is extensive and constantly evolving, keeping us at the forefront of current challenges in the industrial sector.
After more than 75 years in the industry, Concentrol aims to innovate with chemistry for a positive impact on society and the planet. As leaders in the chemical solutions sector, we play a fundamental role in the evolution and continuous improvement of industrial processes. Join us on this journey towards innovation and sustainability!
