Improve your performance with Stahl Carbodiimide Crosslinkers (CDI)

Improve your performance with Stahl Carbodiimide Crosslinkers (CDI)

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Improved performance with Carbodiimide Crosslinkers (CDI)
Crosslinkers help to improve performances like adhesion, toughness, abrasion and chemical resistance. Reactive groups of traditional crosslinkers make them harmful, irritant, sensitizing or even toxic to humans or to the environment. Compared to traditional crosslinkers, such as aziridine, isocyanates, and melamines, polycarbodiimide crosslinkers have a number of advantages.

Stahl Polymers new carbodiimide crosslinkers set a new standard, being the most sustainable, safe and easy-to-use option for high-performance crosslinking. Stahl Polymers recently had the privilege to support some leading global coating producers to make a successful transition from traditional isocyanates and aziridines towards the carbodiimide technology. 

Carbodiimides are defined as non-hazardous under GHS (Global Harmonized System), and most of Stahl Polymers portfolio is Swiss Ordinance compliant for indirect food contact applications. Carbodiimides react at low temperature and offer extended pot life, which make them easy-to-use to formulate high-performance inks, paints and coatings, from do-it-yourself to high-end industrial applications.

Traditional crosslinkers

Often used isocyanate crosslinkers have the disadvantages of having a limited pot life and high-sensibility to moisture. Aziridines have also been the standard for performant crosslinking for a long time. However, their use is decreasing enormously in specific applications due to their toxicity, handling limitations and serious health risks for employees and customers. Even the latest aziridine market developments are still classified.

How does Crosslinking work?

Crosslinking is in fact connecting the polymers through reactive chemistry, this makes sure it strengthens the network of a specific coating. In the case of polycarbodiimides, each molecule contains many reactive groups (-N=C=N-) and reacts with multiple polymer chains, that results in a 3D polymer-crosslinker network via covalent chemical bonds.

Polycarbodiimides (CDI) selectively react with carboxylic acid (-COOH) groups in polymer chains. Due to the high reactivity, crosslinking reaction can take place at room temperature.

Key Benefits of Carbodiimide Crosslinkers

Crosslinkers chemistries overview

Carbodiimide crosslinkers are an excellent alternative to more hazardous crosslinkers. In addition, standard carbodiimides are not sensitive to the presence of water and are able to achieve long pot life. In adapted pH conditions, carbodiimides can be stable in formulation for several weeks.

Aziridine Melamine Isocyanate
 Reacts with -COOH -OH -OH, -NH, Water -COOH
 Pot life Up to 12 hours Very long 1 to 6 hours Up to several weeks
 GHS Symbols None
 R-phrases Muta Cat. 3, R68, R43, R41, R38 Carc. Cat 2, R43/45/52/53 R43, R52/53 None
 Moisture sensitivity High Low Very high Low
 Yellowing High Low Low Low
 Gas release None None CO2 None
 Compatibility glossy resin Good Good Medium Good

* Not all products have all properties

Carbodiimide crosslinkers potfolio overview

Product name
Type Solids (%) Viscosity (cP)
Solvent system VOC (%)
Swiss Ordinance comptiant*
Label on product**
  Picassian® XL-701 Multifunctional 50 25 - 300 MPA 49.9 Yes
  Picassian® XL-702  Standard 40 25 - 300 H2O 0 Yes  -
  Picassian® XL-721
Standard 40 0 - 500 H2O
0 Yes  -
  Picassian® XL-725 Multifunctional
50 50 - 400 PGDA 48.1 Yes  -
  Picassian® XL-732  Multifunctional
100 500 - 2,000  - 0.5 No
  Picassian® XL-752 Standard 30 0 - 150 H2O
0 Yes  -
  Picassian® XL-755 Multifunctional 100 6,000 - 12,000  - 0 Yes   -
  Picassian® XL-762
Standard 100 15,000 - 20,000  - 0 No   -

* For indirect food contact
** Labeling due to solvent or additive, not because of CDI polymer

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Improve your performance with Stahl Carbodiimide Crosslinkers (CDI)
Warren Daniel
Sales Manager Stahl Polymers - North America