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INTUMESCENT MATERIALS WITH IMPROVED FIRE RETARDANT AND FLAME RESISTANT PROPERTIES FOR BUILDING and TRANSPORT APPLICATIONS

Final Report Summary - INTIMIRE (INTUMESCENT MATERIALS WITH IMPROVED FIRE RETARDANT AND FLAME RESISTANT PROPERTIES FOR BUILDING and TRANSPORT APPLICATIONS)

Executive Summary:
The objectives of Intimire are connected with the evolution in the strict CE regulation and standard for fire retardant products:
• the regulations for materials used in railway transport: ST EN 45545
• the novel standards of upholstered furniture: norm NF D 60013
• the evolution of the automotive fire test standard FMVSS 302.

None of the textile products available today achieve the following points: the criteria of new norms, the environment preservation and the requirement of consumer (comfort, price, design ...).

The present approaches in developing flame retardant upholstery fabrics is be no longer sufficient, when novel requirements need to be fulfilled such as:
• An exclusive use of fabrics with a low rate of heat release
• An avoidance of the use of fabrics that spread the fire to other elements with burning droplets.
• No release of toxic gaz.
• Limitation at the minimum rate the smoke (the opacity of smoke threaten lifes during evacuation in case of fire).
• A use of fabrics that are capable to prevent ignition of the underneath layers (foam, or stuffing) even at intense flames (e.g. in railway application against vandalism using flames).

The new material must have two main functions:
• Fire retardant properties: increase the ignition time (not easy to ignite the materials).
• Flame resistant properties: able to stop the propagation of flame, after ignition, and trap toxic gaz.
Currently, there is no textile product able in the same time, to achieve these two properties.
The working principle lies in that Expandable Graphite will expand under high temperature and become char barriers which could reduce the air fluid and resist the fire effectively. Furthermore, it will behave as active carbon to filter smoke when it is expanding.
For these reasons, Flame Retardant Expandable Graphite has not only good performance in fire resistance but also low smoke, no dripping and no damage to human body and environment. These features could meet the future fire resistance tendency.

The achievements of the project are:
• Development of nano graphite as fire retardant additives. These additives have been incorporated in the thermoplastic resin, or back coating resin. In case of fire, the formulation is able to develop a carbon char in order to protect no burnt materials.
• Development of RDT activities to optimize the fire retardant behaviour of polyester and polypropylene with formulation totally free of halogen. The behaviour of each formulation has been analyzed. The criteria of selection of formulation are based on the ignition time rate of heat release and quantity of smoke released during the combustion.
• The tests of spinability have been undertaken for the most performing formulation PET and PP. It is possible to produce multifilament PP on a semi-industrial scale with 10 Wt-10% of the retardant YA whatever the amount of fire retardant YA, a very small decrease in tenacity was noticed whereas the strain at the break decrease with increasing concentration. The fibres produced have developed a low volume of char. Some formulation based on additive YA and synergistic agents seem to give more encouraging results.
• Some additives are focused on the microencapsultation of FR additives. The microencapsulation of additives is a success. Multifilament yarns filled with the microcapsules containing FR were produced and mechanical properties were evaluated. All the formulations selected with the microcapsulated products failed for passing the DIN 4102 (vertical test). The protocol of washing microcapsules has an impact on the performance.
• Some RDT activities have been investigated with the hot melt process.
• In order to optimize the fire retardant behaviour of samples, a back coating able to produce carbon expandable char have been evaluated. The application of fire retardant back coating involves a decrease of heat release.

Association of SME’s has organised dissemination and training session in order to identify the requirements for the transport market and invites their members to create a network with the Intimire consortium.
Formulations have been scales up to semi industrial scale. However, optimisation is still needed to perform an acceptable industrial production. The ultimate goal is to scale up the selected formulation at the semi-industrial scale and industrial scale. This type of fibres shoes does not exist on the market. The final intumescent structure based on blend of yarns (intumescent or not), or based on fire retardant coating should answer to the new requirements of norms for public places, transports (example: CEN 45-554 for railways applications).
Project Context and Objectives:
The INTIMIRE project targets the production of new fire retardant and flame resistant polyester (PET) and polypropylene (PP) fibres, films and upholstery end products based on the original intumescent flame retardancy concept. These products will offer a technical solution to the evolution in requirements defined in upcoming European norms for upholstered furniture and railway transportation. They also must offer improved durability and thermomechanical properties.

INTIMIRE’s first motivation is to address specific problems faced by European SMEs textile industries. They are connected with the evolution in the strict EC regulations and standards for fire retardant products:
• the regulations for materials used in railway transportation: ST EN 45545
• the novel standards of upholstered furniture: norm NF D 60-13

None of the textile products available today, achieves the following points: the criteria of new norms, the environment preservation and the requirement of consumer (comfort, price, design, ...).

The current approaches in developing flame retardant upholstery fabrics are no longer sufficient when novel requirements need to be fulfilled such as:
• an exclusive use of fabrics with a low rate of heat release
• an avoidance of the use of fabrics that spread the fire to other elements with burning droplets.
• a use of fabrics able to prevent ignition of the underneath layers (foam, or stuffing) even at intense flames (e.g. in railway application against vandalism using flames).

In order to achieve the criteria of the new standards, it is mandatory for upholstery fabrics to offer a much higher level of fire protection than what had to be fulfilled up to now. The standard flame retardant polyester fibres and certainly the existing flame retardant PP fibres (using halogen based flame retardants) will not be able to fulfil all these requirements.

It is very important to notice that the fire behaviour of complete materials (complex made of foams + textile covering) have no relation with the fire behaviour of component, if taken individually. For example, the following figure present the Rate of Heat Release of polyurethane foam, the one of fire retardant textile polyester structure and the one of the two elements bounded. It is clear that textile structure is not able to protect the foam, as the curve of the complex tends to be similar to the foam to be protected.

Even the flame retardant back-coatings used today need to be dramatically improved to prevent the ignition of the foam underneath the fabric . The new material must have two main functions:
• fire retardant properties: decrease the ignition time (not easy to ignite the materials)
• flame resistant properties: able to stop the propagation of flame, after ignition
Currently, there is no textile product able in the same time, to achieve these two properties.

The objectives of Intimire are :
• To develop a formulation able to promote an intumescent system in case of fire, at low rate for polyester. The main challenge is to disperse a low quantity of additives, homogeneously during the extrusion of fibre and to improve the mechanical properties of fibres.
• To find synergy agents able to improve the performance of standard additives in order to perform improved mechanical properties and to decrease the cost fibres.
• To process nano graphite in polyester fibre, in safe working conditions.
• To develop at pilot line intumescent fibres in order to realise non woven, woven, and knitting fabrics, able to be used for transport and home furniture applications.
• To promote intumescent textile support able to couple fire resistance properties and flame resistance properties. The ultimate goal is in case of fire hazard to develop a thermal insulating barrier able to protect the foam or element under the textile support.
• To promote 3 types of demonstrators: elements for filters, railways’ textile seat and upholstery chair.
• To validate the performances of new materials according to new European standard.
Project Results:
Industrial requirements have been set up first, and intumescent fire retardant formulation for PET and PP polymer at laboratory scale were performed. The main objectives were:
• To characterise physically and chemically the raw material thanks to normalised methods.
• To characterise the mechanism of thermal degradation and fire behaviour under approached conditions of fire (irradiance in the range of 30 kW/m²).
• To select additives able to promote intumescent phenomena for polypropylene and for polyester
• To develop fire retardant masterbatch for polyester and for polypropylene at laboratory and pilot scale
• To characterise the fire behaviour and the thermal degradation of treated masterbatch

The project allowed to obtain characterization and fire retardant methods:

Concerning thermal degradation analysis (Thermogravimetric Analysis (TGA)), this method can be used to evaluate the thermal stability of the basic components (additives and polymers) and produced blends.
Concerning fire behaviour characterization, depending on the final application and the existing standards, a lot of tests exist to which the material could be submitted.
In a first step, two discriminative and interesting tests were used:
– Cone calorimeter test (ISO 5660-1 used for railways applications)
– Smoke chamber test (ISO 5659-2 used for railways applications)
– Horizontal flammability test (FMVSS 302)

The main objectives of the development of intumescent fibres based on polypropylene and polyester were:
• To produce at laboratory scale synthetic fibres able to promote a carbon char in case of fire, based on polypropylene or polyester matrix
• To characterise the fire behaviour and thermal degradation of manufactured products.
• To provide knowledge basis for the processing routes for the charged polymer, in order to scale up to industrial feasible production processes
The main results obtained is the development of fibers at different scales. Spinability was evaluated at laboratory scale, fibers were evaluated at the semi-industrial scale. 8 formulations lead to the production of fibres, from few grams to 1 kilogram. 6 formulations were based on polypropylene, 2 formulations were based on polyester.

Based on the fibres obtained, it was targete a development of high added value textile structures able to promote thermal insulation barrier in case of hazard. The main objectives were:
• To define the appropriate processing routes to prepare textile support from fibres manufactured
• To study the impact of structure and composition of textiles on the fire behaviour and heat resistance
• To develop integrated finishing process according to the need of end user
2 ways to produce textile structures were investigated: knitted and nonwoven. 8 knitted structures were obtained, and 1 nonwoven structure.

Flame-retardant coatings were developed based on acrylic and polyurethane binders, and applied on textile structures.

The textile structures (either with FR fibres, either with FR coating) were tested. However, the results returns in a general ways with low performances, with sometimes no improvement from the FR additive comparing the non FR textile structure and the FR one. The bottlenecks are the following:
- Quantity of additives to achieve fire retardant properties
- Difficulty to incorporate the additive in polymer matrix (temperature of degradation of polymer matrix, quality of dispersion, avoid the agglomerates)
- Difficulty to spin the fibres including the charges (management of viscosity of treated polymer, couple fire retardant properties and mechanical properties)

Alternatives plan in order to achieve fire retardant fibres based on intumescent fibres could be:
- Test different formulations to promote carbone char based on graphite, phosphorus component.
- Associate synergy agent (cost, compatibility with matrix and other additives, difficulty to spin the formulation.
- Development of additives with a small diameter.
- Development of microencaspulatives formulation.
- Development of back coating or hot melt.

The advantages of Intumescent system remains the following:
- Halogen free
- No toxic gas in case of fire
- Formation of carbon char able to protect other material
- Low impacts on environment
The limits today of Intumescent system for textiles application are the quantity of additives to reach the fire retardant properties, and the spinability of formulations.


Potential Impact:
The demand for products in home Textiles, fluctuates broadly in line with the economic cycle (real incomes, unemployment levels, interest rates, etc). This cyclicality, in the case of home Textile end products demand (such as beds, upholstered furniture and carpets) is more highly variable than most other end-use segments, where purchase does not represent such a major investment for the consumer (e.g. waterproof coats), replacement cannot be easily postponed (e.g. car tyres, protective clothing) or where demand is less closely related to the economic cycle (e.g. medical products).

A positive influence on the demand for Hometech end products relates to trends in contract applications, where the demand is closely linked with the level of activity in the more general levels of infrastructure development, construction and capital spending (e.g. new and refurbished offices, hospitals, and hotels).

The markets for most traditional products such as carpets, furnishing fabrics and mattresses are fairly mature in Western economies. However, over recent years, as result of more stringent FR regulations in the major developed markets Flame Retardant textiles have increased their share.

Share of flame retardant textiles
Curtains 8 %
Drapes 20 %
Upholstery fabrics 39 %
Blankets 5 %
Bedspreads 5 %
Bedding 2 %
Mattresses Thicking 2 %

Concerning textile for transport : today the transportation sector represents the single most valuable world market for technical textiles
In this scenario, as economic expansion is generating demand for a better system of transport and rail freight continues to account for a small percentage of inland goods traffic, cars and other commercial vehicles will be used in increasing numbers. If the demand for cars is heavily dependent on real personal income, the demand for commercial and public service vehicles is more closely correlated with economic and population growth and the increased need to move people and goods.
Moreover as the private car will be priced out of many city centres and the work journeys will continue to grow, the provision of increasingly sophisticated and efficient public transport solutions will increase worldwide. International trade will need larger volumes of goods and huge number of people to be transported with the additional demand for larger, faster and more economical ships and aircraft.

Passenger car applications still largely dominate the transport sector, setting the pace for engineered textile products and high quality in volume markets.

In passenger cars textile products range from lightweight nonwovens used in filters through, a variety of interior trim (woven and nonwoven), tufted or needlepunched carpets, seat fabrics of various types.

In commercial vehicles, furnishing textiles generally play a less important role in commercial vehicles compared with passenger cars. However, the technical requirements of textiles in many end-uses are even more critical and demanding because of the heavier use to which they are continually subjected.
Performance furnishing materials play a more essential role in public service vehicles(buses, coaches, trams and trains) where they must provide high levels of durability and safety (particularly fire retardancy) as well as good aesthetic appeal.

In car textiles market there is a huge range in the amount of textiles used in motor vehicles with different required methods of evaluation and standards of performance


The impact of the INTIMIRE project outcomes for the partners are the following:
• Development of new range of products more environmentally friendly, simplier and cost effective solutions
• Creation of network to find new customers and create a high level knowledge about the fire behaviour characterisation
• Development of fire retardant structure through the members of IVGT
• Identification of the needs of some end users
• Creation of dynamic networking for advanced textiles materials
• Development of lightweight structures based on textile with improved thermal resistance and fire retardant properties
• New products based on fire retardant properties (advantages)
• Synergies among all those operating in this field
• Contacts with institutions, customers and potential users in Europe and abroad as well as with European and International associations and key authorities (CEN, Euratex, IFAI)
• Promotion through participation to fairs in Europe and abroad, conferences, press
• Development of fire retardant materials for textile applications
• Optimisation of process for dispersion
• Network built-up: fire retardant additives producers and textile companies
• Increase the knowledge of its members about the fire retardant additives and legislation
• Scale up of production of textile across several members
• Organisation of international technological day
• Reinforce the links between SME’s and RTD performers
• Creation of network
• Protocol adapted to the textile structures
• Formulation based on biosourced additives
• Development of ecofriendly treatment for polypropylene fibres based on microencapsulated products
• Creation of networking about fire retardant additives and advanced textile materials

List of Websites:
http://intimire.ensait.fr/