Introduction

In the Performance Materials and Adhesives divisions, at Concentrol we work to manufacture products for the automotive sector: mould release agents, silicone stabilizers for polyurethane foam, hot melt adhesives, water-based adhesives and surface finishes. Our team of experts studies the needs of the market and develops solutions in our laboratories to meet the needs of the sector.

For the automotive industry, the ‘Seats and headrests’ sector is vital for the manufacture of transport vehicles. Throughout this article, we understand the concept of this automotive sector as all seats, backrests and headrests made of flexible polyurethane foam for cars, buses, trucks, trains, and motorcycles, among others.

 

The role of the release agent and product range

The release agent is a basic element in the manufacture of moulded polyurethane foams. Due to the very high adhesion property of PU in its forming process, it is necessary that once the part is formed it can be easily removed. Therefore, there are different options, the most common are:

  • Silicone moulds: valid only for certain types of parts with low deficiencies and properties.
  • Teflon coated: very expensive, delicate and hardly amortizable investments.
  • Release agents: non-stick patina applied to the mould that acts as a barrier between itself and the PU.

 

Manufacturing processes

The choice of release agent will depend on the manufacturing process of the seats and headrests. There are 2 major categories: firstly, hot curing foaming; and, secondly, cold-curing foaming (PU H.R. – ‘high resilience’ foam). There is also a third ‘in situ’ process, which is essentially cold-cured, but due to its highly differentiated characteristics, it deserves a separate mention.

Hot cure foaming is used for seat making only. It is a very high temperature manufacturing process with long cycle times. The release agents used in this case are water-based and these are usually diluted from 1: 3 to 1: 8 with application by air-less spray.

On the other hand, the cold curing process works with lower temperatures and shorter cycle times. In this case, the entire range of release agents can be used: water-based, hybrid, co-solvent and solvent-based. The application will depend on each process. It can be applied by airless spray, airbrush, airmix or brush.

 

Lastly, the ‘in situ’ process in seats requires that one of the faces of the mould be covered with the fabric and the frame, in such a way that, when removing the part, the seat is already finished and does not require the sheathing operation (which is mandatory in the classical process). This implies that the release agent is only applied to the foamed side of the mould. The entire range of release agents can also be used here: water-based, hybrid, co-solvent and solvent-based.

Headrests are frequently produced by the ‘in situ’ system, although any of the aforementioned processes is viable, the total ‘in situ’ can be added where no release agent is used.


Stages in the manufacture of the part

 

    • Cleaning of moulds:: by physical abrasion (cryogenic, manual brushing, etc.).
    • Preparation of the mould: reinforcing paste and / or several layers of release agent while empty.
    • Stabilization of the mould at the required temperature.
    • Application of the release agent (manual or by robot). Below you can see the following video of the release agent application in the manufacturing process of a seat: CONCENTROL Application Capsule: Mould Release Agent for Flexible PU Foam
    • Mould fillings, depending on the part, with metal parts, pivots, reinforcement materials, etc.
  • Polyurethane injection.
  • Part extraction.
  • Decompression of the part.
  • Repair the part if necessary.
  • Storage.

 

Concentrol product lines

-Release agents for hot curing foam

-Water-based mould release agents, concentrates to dilute. Different options depending on the client’s requirements: softness, anti-noise effect, etc.

-Release agents for cold curing foam

-Solvent base

  • Release agents ready for use. Flash point <21ºC (Class I)
  • Ready-to-use concentrated release agents. Flash point> 23º C (Class II)
  • Ready-to-use concentrated release agents. Flash point> 55º C (Class III)
  • Concentrated release agents to dilute.

-Cosolventes e híbridos

  • Release agents ready for use in different water-solvent ratio, from 70% water – 30% solvent

-Water based

  • Release agents ready for use.
  • Concentrated release agents to dilut

Main advantages and disadvantages of each line

  • Solvent base: 

 

Advantages Disadvantages
Wide working range Low flash point applicable ATEX regulations
Quick drying Toxicity and emissions
Easy cleaning by scraping, melting or blasting
Easily applicable: brush, airless, airmix, airbrush

 

  • Water based 

 

Advantages Disadvantages
Low toxicity and emissions Danger of destabilization of the emulsion by cold
Better work environment Slower drying
Non-flammable Greasy soiling of mould holder in greasy finishes. Mandatory blast cleaning
Anti-noise effect on greasy finishes Impossibility of gluing elements on greasy finishes
Less soiling inside the mould, the more greasy the less soilingPossibility of allergies in greasy finishes
Mandatory airmix or airbrush application

 

Hybrid and Co-solvent


Depending on the water-solvent ratio, they mainly acquire the advantages and disadvantages of each component.

For example, a 30% solvent hybrid mould release agent will have only 30% VOC emissions compared to the 90% emission of a class II or class III solvent release agent. On the other hand, if we compare it with a water-based one that can have an emission of 0% of VOC, the hybrid will maintain a dry finish of the part without greasy residue.

 

Other Concentrol products

Concentrol also offers other products for the seat and headrest sector: silicone stabilizers or surfactants (for suppliers or manufacturers of the polyurethane system from which the seat foam is formulated or manufacturers of seats that are self-formulating); reinforcement pastes (to prepare the mould after cleaning or to reinforce difficult areas); contact adhesives (for the repair of polyurethane foams or the union of these with other materials); anti-noise coatings (they provide anti-noise touch properties); and slippery coatings (they provide slippery properties and an extraordinarily soft and anti-noise touch to the surface).