Polyols for one-component assembly foams (OCF)

Polymer materials have been used in construction as structural and insulating elements for over 40 years. The key role here is played by the one-component polyurethane foam (OCF), which is commonly referred to as assembly foam. The name “one-component foam” derives from the production technology. Polyurethanes (so also the OCF) are chemically cured polymers which each time require mixing two interacting components A and B to obtain the target material. A single container with an OCF includes a product being ready for use. It is something that makes OCFs stand out from other (two-component) polyurethane foams. Since a one-component foam is packed into a pressurized metal can (which usually weighs up to 1 kg), it can be quickly and easily applied with the use of a special gun or a plastic hose. Once released from the can, OCFs (also called 1K foams) are cured by the moisture contained in the air.

OCFs are usually classified by:

the method of application. We distinguish gun foams (designed for professional use) and hose foams (for amateurs / so-called Do-It-Yourself (DYI) foams). Professional foams can be applied multiple times with a special gun. DYI foams are designed for a single use and are applied with a special hose attached to the packaging.

the temperature of application. The temperature of application. Summer foams can be applied at +5C to +35C. Winter foams can be applied at -15C to 25C. All-season foams can be applied at - 5C to +30C.

flammability class. We distinguish foams that meet the requirements for classes B1, B2 and B3. Class B1 includes fire-retardant products, B2 stands for products of normal flammability, while B3 designates the most flammable products. The products classified as B3 contain no fire retardants. The products classified as B2 normally contain a fire retardant called TCPP.

foam efficiency. The use of appropriate polyols causes the formation of standard foams or high-performance foams (called megafoams). The efficiency of assembly foams is defined by the length of the line formed after application. Normally, a single container of a gun-applied assembly foam (680 g) is enough to produce an around 100 m line of foam being 20 mm in diameter, or 45 dm3 of a cured foam. Polyols for the megafoams are base polyols that improve the structure and efficiency of foam by even 20%. The foam they produce features a noticeably finer and more regular cellular structure.

How are OCFs produced

The unique nature of the OCFs in the world of polyurethanes is proved by the fact that a single container is filled with a ready-to-use product. This is the most important difference compared to other types of polyurethane foams, most of which require mixing at least two components. The main constituents of PU foams, including OCFs, are polyols, isocyanates and additives such as catalysts, foam stabilisers, plasticisers and fire retardants. When producing the OCFs, all these components are packed into a metal can which is then filled with a mixture of liquefied gases called propellants via a special valve. Once all components are mixed in the can, they slowly start to react with one another to form a special polymer.

Application of the foam

Work on assembly foams requires general training in their use due to the risk of igniting the foam, which contains flammable gases. Any incautious transport or storage of the cans may cause them to break or explode. While working on an OCF, we must exercise particular caution and use personal protective clothing, especially protective gloves and goggles. During application, we must also remember about adequate ventilation in the room.

Properly selected polyols and other components of the formulation will give us not only a foam with the desired properties but will also enable problem-free application even 18 months after the foam was produced. The final polymerisation (curing) occurs only once the foam is released from the container. It is induced by moisture contained in the air and substrate, which reacts with the prepolymer and the excess isocyanate contained in the mixture. The foam normally stops bonding in only 4–5 minutes (forming a skin), and after 30 minutes it is suitable for processing (e.g., cutting). The foam is fully cured after 24 hours.

In the case of the special 1.5K foams, the can additionally accommodates a small container with a curing agent, which makes the foam cure even faster and independently of air humidity. The curing agent is released with a special knob, and then the whole formulation is mixed by shaking. A flaw of this solution is that we cannot interrupt our work. The foam should be released in 6 minutes from the moment it was mixed with the curing agent. After that time, the foam will cure inside the container, which may cause the container to burst.

Polyols by PCC Rokita

OCFs contain isocyanates, polyols and additives. At PCC Rokita, we have rapidly extended our range of polyols designed for OCF production. These include polyetherols and polyesterols. Their main advantage is the composition and structure, which are suitable for formulating OCFs.

Standard polyether polyols

designed for OCFs

This is a group of polyether polyols mostly used in the industry, which are long-molecule substances formed by reaction between a short alcohol and propylene and ethylene oxides

Their production technology, developed by PCC Rokita, allows for choosing an appropriate length and composition of polyol chains based on the final properties of the OCF.

Specialised polyether polyols designed for OCFs

These include specially designed polyether polyols used to produce high-quality OCFs. With the Rokopol^® iCan products, we can produce assembly foams with increased performance parameters, for example a higher efficiency or reduced processing time.

Polyols for the megafoams are base polyols that improve the structure and efficiency of foam by even 20%. The foam they produce features a noticeably finer and more regular cellular structure.

The polyols for winter OCFs can be used as base polyols or as foam additives. They reduce the foam’s curing time by even 25% and improve its efficiency by 15%, while maintaining the other properties of the foam at an acceptable level. OCFs based on Rokopol® iCan 2770 and Rokopol® iCan 4100 polyols can be applied even at negative outside temperatures (up to -20°C).

Polyols for economic foams are such polyols that allow for the use of a high quantity of chlorinated paraffin in the foam formulation (even 65% in component A). They also reduce the foam curing and drying times. Foams based on Rokopol® iCan 2672 and Rokopol® iCan 2850 polyols maintain a good dimensional stability of the foam and feature a homogeneous fine-cellular structure.

Polyols for high-elasticity foams are specialised polyols which increase the elasticity and reduce the brittleness of the foam. They additionally allow for reducing PMDI consumption to 10–15%.

Polyester polyols for OCFs

These are polyesterols with an aliphatic, aromatic or mixed structure. The Rokester products enable the production of OCFs featuring a better dimensional stability and a fine-cellular and regular structure. In addition, they reduce the flammability of the produced OCFs.

Polyols for fire-resistant foams with flammability class B2: special low-reactivity polyester polyols. They reduce PMDI consumption. They improve the efficiency of OCFs. Plus they increase the foam’s mechanical strength and dimensional stability.

Polyols for high-performance and universal foams. Aromatic polyols with controlled reactivity. They improve the efficiency of OCFs. Plus they increase the foam’s mechanical strength and dimensional stability.

Polyols for summer foams and economic foams. Aromatic polyols with a high hydroxyl value. They contain a large amount of chlorinated paraffin. They increase the dimensional stability of the foam.

Additives and propellants for OCF foams

Besides the basic raw materials (polyols and isocyanates), polyurethanes are made with the use of modifiers and propellants (gases).

Fire retardants: one of the most important modifiers. Fire retardants added to OCFs increase their fire resistance and reduce the flame spread rate in the event of ignition. Fire retardants considerably decrease the viscosity of the foam and allow for producing an OCF that complies with DIN 4102-1 (flammability class B2). Containers with OCFs do not have to be marked with signal word H411 or pictogram K411.

Propellants: Dimethyl ether (DME): a liquefied carrier gas (propellant) contained in a can with an OCF (in addition to the warm components A and B).

Application of OCFs

A modern finishing material used in construction, e.g. for the installation of doors and windows, the insulation of water and heating systems, or the filling of gaps in roofs and floors.

construction binder (foamed adhesive) – excellent adhesion to many construction substrates: brick, concrete, stone, wood, plastics, plaster, glass, metal, styrofoam, rigid PUR foams

setting and sealing of door and window frames

filling and noise suppression in partition walls and prefabricated members in framework structures

heat and sound insulation of floors, sealing of partition walls and car interiors

filling of components in framework structures

filling of gaps and furrows for pipes and installation lines in walls, floors and roofs

fixing and sealing of roof joints, walls and floors

all finishing works

Properties of OCFs

A modern finishing material, extremely easy to apply, most often used for sealing doors and windows as well as filling construction gaps.

protection against corrosion

short curing time

quick application, easy and safe use

heat and sound insulation

resistance to moisture – they do not absorb or accumulate moisture from the air

dimensional stability (no shrinking or re-expansion)

they increase their volume after application, so they can tightly fill all gaps

they are easy to process or cut, and can be covered with mortars, plasters or paints

safety – they are self-extinguishing; once the heat source is cut off, a foam classified as B1 or B2 goes out by itself.

One-component assembly foams (OCF)

Assembly foams (OCFs)

How are OCFs produced

Application of the foam

Polyols by PCC Rokita

Standard polyether polyols

The Rokopol^® range

Specialised polyether polyols designed for OCFs

The Rokopol® iCan range

Polyester polyols for OCFs

The Rokester® range

Additives and propellants for OCF foams

Roflam and DME series

Application of OCFs

Properties of OCFs

One-component assembly foams (OCF)

Assembly foams (OCFs)

How are OCFs produced

Application of the foam

Polyols by PCC Rokita

Standard polyether polyols

The Rokopol® range

Specialised polyether polyols designed for OCFs

The Rokopol® iCan range

Polyester polyols for OCFs

The Rokester® range

Additives and propellants for OCF foams

Roflam and DME series

Application of OCFs

Properties of OCFs

The Rokopol^® range