At present we can find multiple applications of polyurethane in many areas, due to its great versatility and its insulating efficiency. At Concentrol we currently offer an extensive range of chemical specialties that includes release agents and silicone surfactants specially designed for the manufacture of polyurethane foam insulating panels.

In the sector of polyurethane panels and blocks, we can differentiate two main types of applications that are used in the technical insulation and construction industries: insulating sandwich panels (continuous or discontinuous) and box mold blocks made from rigid polyurethane foam. Their increasingly widespread use is due to the fact that they not only provide thermal and acoustic insulation, but also work as a waterproofing and enclosing agent, with solutions that are light as well as resistant.

Polyurethane

A polyurethane system is made up of two types of liquid components that, through the chemical reaction that is generated between them, give rise to polyurethane foam:

  1. a) Firstly, polyols to which other chemical additives are added (such as catalysts, silicones, blowing agents, etc.)
  2. b) Secondly, isocyanates, such as TDI, MDI, MMDI, PMDI, or pre-polymers.

Currently, the sector that generates the highest consumption and demand for polyurethane panels and blocks is industrial and residential construction and building. The main application in this market is formulated and semi-formulated polyurethane systems that allow closed or open cell rigid foams to be obtained.

One of the most interesting solutions in this sector is sandwich panels formed by an insulating core of rigid polyurethane (PUR) or poly-isocyanurate (PIR) foam adhered to two steel or aluminium metal profiles.

The PIR (polyisocyanurate foam) variety looks almost like polyurethane (PUR) foam, but has different thermal and mechanical properties. The main difference is the reaction of PIR foam to fire, forming a carbonated surface layer that protects and prevents the fire from penetrating the internal layers of the panel. This greater resistance to fire allows these solutions to obtain the BS2D0 or BS1D0 certification. The UNE-EN 13501 standard is detailed below, with the different possibilities in the results: 

Source: https://www.une.org/

This table summarizes some main technical differences between a PUR and PIR panel: 

PURPIR
Components line4-55
Density35-40 kg/m341-43 kg/m3
Press temperature35-42ºC50-60ºC
Sheet temperature30-35ºC40-45ºC
Adherence promoterNO

 

Applications of polyurethane systems

PUR and PIR sandwich panels with continuous technology are used both with metallic and flexible coatings, in enclosures (for facades and roofs), in cold rooms and in general as insulation in construction. PUR and PIR sandwich panels with discontinuous technology are used for their thermal properties in the cold industry. Finally, rigid foam blocks are also a polyurethane application that is used in different sectors.

Requirements of polyurethane foams

The main requirements of rigid polyurethane foam are:

– Thermal insulation properties (closed cell structure and low conductivity)

– Good adhesion to different substrates

– Dimensional stability

– Flame retardant properties

– No surface defects

– Good fluidity (refrigerated and discontinuous)

Coefficient of thermal conductivity (λ)

The thermal conductivity of a material is the property that it has to transmit heat, allowing the passage of kinetic energy from its molecules to adjacent substances. Thermal conductivity is calculated from a coefficient (λ ‘lambda’) and will differ depending on the molecular nature of each material, measuring how well a material conducts heat in units of watts over meters Kelvin (W / m·K).

The calculation is carried out with the following formula, where q is the heat flux per unit of time and area, and grad. T is the temperature gradient:

λ = q/grad. T

For insulation, the lower the lambda value, the better the thermal performance. Polyurethane sandwich panels are one of the materials on the market that currently has the lowest coefficient of thermal conductivity, which is why its use as a constructive element for thermal insulation has spread. The λ value is usually less than 0.025 (W / m · K), always measured at a temperature of 10ºC. For this reason, the required thickness is also usually lower compared to other types of insulating materials.

Source: https://www.camarasfrigorificas.es/blog/comportamiento-del-panel-sandwich/

Source: https://concepto.de/conductividad-termica/#ixzz6zNJr4ZVM

 

Concentrol’s range

Silicone stabilizers

In choosing the optimal stabilizer (or surfactant) for each polyurethane system, both chemical requirements and those related to the manufacturing process must be considered.

The chemical requirements are related to the type of polyol, isocyanate and blowing agent used. The influence of other components such as catalysts must also be considered. The most important points to consider regarding the process include effective mixing, curing conditions, and the flow demands of the casting. Our stabilizers are developed for each specific application, considering the foaming agent, which plays a critical role in each formulation.

 

Advantages of Concentrol’s range of stabilizers -STB PU-22XX-

Concentrol surfactants meet the main needs and requirements of rigid polyurethane producers:

  • A wide selection of additives that allows to offer a different stabilizing power for the MDI, TDI / MDI and TDI systems, also providing different proportions in cell regulation.
  • Cell regulation and internal stabilization can be adjusted to obtain good quality foams with improved processability.
  • Lambda optimization
  • Optimization of flowability
  • Optimization of B2 test results (PUR / PIR)
  • Options for different blowing agents
  • Possibility to choose options free from SHVC (following market trend)
  • Options of partially or fully coated surfactants
  • Adhesion regulation option
  • Custom developed products
  • Flexible R&D
  • Flexible production conditions (batches from 200 kg to 10 t)

 

Release agents

Within the three detailed applications, it is necessary to differentiate in each case when release agents are used or not:

  • With regard to continuous sandwich panels, silicone paper is usually used on the sides of the panels, so in many cases it is not necessary to use a release agent. Now, in those processes in which one of the sides is used a continuous carousel of side-blocks (high-density PE pieces), in that case a solvent-based release agent is applied by spraying it on top of these pieces using an airbrush gun.
  • Likewise, in the case of discontinuous sandwich panels, we distinguish those in which the panels are completely closed on all four sides, in which a release agent would not be used, except in areas where foam overflows, an area in which release agent could be applied on top of the panel to facilitate the removal of the rigid PU more easily. Now the productions in which the discontinuous lateral panels are opened in the longitudinal zone on both sides, solvent-based release agents are generally used, but also, depending on the case, a water-based release agent can be used. In general, release agents are generally applied by spray gun, but they can also be applied by brush.
  • In the case of box molds, release agents are applied in a simple and rudimentary way, sometimes using brooms that wet the entire surface of the mold. We have noticed in some cases that some clients also use semi-permanent release agents, so that the release agent does not transfer from the mold to the piece and allows not having to apply release agent in each injection.

 

Main product lines

Some solvent-based products that we have at Concentrol are: CONCENTROL LP RD-8-6 (*) which has a dry finish, easy to degrease, for rigid foam imitation wood and automobiles. CONCENTROL LP RD-07 BT has a slightly greasy finish and is especially suitable for discontinuous sandwich panels. CONCENTROL LP RD-5 ASA (*) and CONCENTROL LP RD-5 ASC laminated leather finish, discontinuous insulating panel, concentrated to dilute with CONCENTROL LP RD-5 ASA (*), with a laminated leather finish and applied to discontinuous insulating panels.

* These products do not contain silicone

Concentrol offers an extensive range of chemical specialties, such as silicone release agents and surfactants, essential in the manufacture of these polyurethane foam insulating panels for different applications. In addition, by providing personalized attention, we are able to adapt the products to the requirements and needs of each client.