Exolit® OP 550
Highly effective reactive, non-halogenated phosphorus polyol

Exolit® OP 550

Highly effective reactive, non-halogenated phosphorus polyol

Edition Date :
October 14, 2020
Clariant’s Exolit OP 550 is a flame retardant specifically designed for flexible polyurethane foams. The product is a reactive flame retardant that can be chemically reacted into the PU matrix, preventing unwanted migration from the material. Therefore, very stringent emission standards for PU flexible foams can be achieved. This makes the product suitable for low VOC applications, for example in the automotive industry. Exolit OP 550 is a medium-viscosity liquid, based on a non-halogenated phosphorus polyol with a functionality of approx. 2.

  • Non-halogenated flame retardants with favorable environmental and health profile
  • Reactive flame retardant for low-VOC applications, allows meeting demanding emission standards like Fogging or VDA 278
  • Low migration from the polymer matrix due to chemical incorporation prevents fading of the flame-retardant performance
  • High phosphorus content allows superior flame-retardant efficiency at low dosages
  • Medium viscosity liquid for easy processing

For regulatory details such as the classification and labelling as dangerous substances or goods please refer to our corresponding Material Safety Data Sheet.

CharacteristicsUnit   Target value   DS¹) TD²)Test method
Phosphorus            %(w/w)   16.0 - 18.0  

Photometry after oxidizing dissolution; (11/17)
Density            g/cm³   1.31  

at 25 °C
Viscosity            mPas   max. 3,500  

Brookfield viscosimeter, 25 °C; (11/30)
Color Number (Hazen, APHA)Hazen   max. 600  

Spectrophotometry; (11/22)
Acid Numbermg KOH/g   max. 2  

Titration using alkali; (11/11)
Hydroxyl Numbermg KOH/g max. 170  

Double Karl-Fischer-titration; (11/14)
¹) Delivery specification: The product is monitored on a regular basis to ensure that it adheres to the specified values. Test methods: Clariant method numbers 11/xx in brackets.
²) Technical data: The technical data are used solely to describe the product and are not subject to regular monitoring.
  • Exolit OP 550 is primarily suited for flame-retarded flexible PU foams, including both polyether- and polyester polyol-based materials.
  • Typical application examples include production of automotive slabstock and molded foam. FMVSS 302 class SE foams can be achieved with dosages of 2-8 php, depending on the density.
  • Exolit OP 550 can replace scrutinized volatile flame retardants including TCPP.
  • Application in other PU material types like integral skin foam, coatings, adhesives, sealants and elastomers is also possible.
  • The use of an anti-scorching agent is recommended when processing Exolit OP 550 in low-density foams, e.g. products like Irgastab® PUR 70 from BASF SE.
  • Exolit OP 550 is particularly suitable for self-formulating PU producers. Long-term storage in water-containing PU systems is not recommended.
  • Guide formulations for standard applications are available on request.
Delivery form

Exolit OP 550 is supplied in following packaging units:
1 kg sample bottles
50 kg PE open head drums (9 drums per pallet)
1.000 kg net in non-returnable 1.000 liter semi bulk containers

In the presence of moisture or water Exolit OP 550 hydrolyses slowly and should therefore be stored and handled in such a way to exclude any potential sources of moisture.

Minimum shelf life is 12 months from the date of shipping when stored according to the said conditions.

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Alexis Dudley
Alexis Dudley
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This information corresponds to the present state of our knowledge and is intended as a general description of our products and their possible applications. Clariant makes no warranties, express or implied, as to the information’s accuracy, adequacy, sufficiency or freedom from defect and assumes no liability in connection with any use of this information. Any user of this product is responsible for determining the suitability of Clariant’s products for its particular application.<br />
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