What Is Dimeryl Diisocyanate (DDI)?

 Dimeryl Diisocyanate (DDI), also known as Dimer Acid Diisocyanate (CAS No. 68239-06-5), is a long-chain aliphatic diisocyanate widely used in the production of high-performance polyurethane materials. The DDI molecule contains two reactive isocyanate groups (–NCO), which react with polyols to form polyurethane networks.

Due to its long aliphatic backbone and hydrophobic structure, DDI significantly enhances flexibility, water resistance, and durability in polyurethane systems. It is therefore considered an important raw material for advanced polyurethane formulations.

Compared with conventional diisocyanates such as MDI, TDI, or HDI, DDI features an aliphatic structure with low volatility and superior resistance to yellowing, making it particularly suitable for applications requiring enhanced stability and improved safety profiles.

1. Primary Functions of Dimeryl Diisocyanate

(1) Enhancement of Flexibility

One of the most important functions of DDI is the improvement of material flexibility. Its long-chain structure introduces flexible segments into the polyurethane backbone, resulting in higher elongation at break and improved resilience.

DDI-based polyurethane elastomers exhibit excellent resistance to cracking under repeated bending or impact loading, making them particularly suitable for elastomeric and sealing applications.


(2) Improved Hydrolytic Stability

The strong hydrophobic nature of DDI reduces water uptake in polyurethane materials.

As a result, DDI-based polyurethanes maintain stable mechanical properties in humid or aqueous environments. This characteristic makes DDI particularly suitable for:

  • Waterproofing materials

  • Polyurethane products used in moisture-prone conditions


(3) Enhanced Weather Resistance

As an aliphatic diisocyanate, DDI does not contain aromatic rings.

Consequently, DDI-based polyurethanes exhibit:

  • Reduced yellowing under UV exposure

  • Slower material degradation in outdoor environments

This makes DDI suitable for:

  • Weather-resistant coatings

  • Construction sealants

  • Outdoor polyurethane systems


(4) Low Volatility and Improved Processing Safety

DDI has a relatively high molecular weight and low vapor pressure, leading to:

  • Reduced odor during processing

  • Lower volatility compared with many conventional isocyanates

These features contribute to improved workplace conditions and enhanced safety management in polyurethane manufacturing.

2. Major Applications of Dimeryl Diisocyanate

The applications of DDI are primarily concentrated in high-performance polyurethane materials.

(1) Polyurethane Elastomers

DDI-based elastomers provide:

  • Excellent elasticity

  • Strong impact resistance

Typical applications include:

  • Industrial rollers

  • Wear-resistant mining components

  • Vibration-damping elements


(2) Polyurethane Coatings

DDI-based polyurethane systems are used in:

  • Flexible anticorrosion coatings

  • Weather-resistant topcoats

These coatings offer improved:

  • Adhesion

  • Crack resistance

  • Long-term durability


(3) Adhesives and Sealants

DDI is commonly utilized in:

  • Electronic sealants

  • Industrial adhesives

It provides enhanced flexibility and long-term bonding stability.


(4) Electronic Encapsulation Materials

Due to low water absorption and high chemical stability, DDI-based polyurethanes are suitable for:

  • Electronic potting compounds

  • Protective encapsulation coatings

3. Why Choose Dimeryl Diisocyanate?

For polyurethane manufacturers and chemical procurement professionals, DDI offers several distinct advantages:

  1. Enhanced flexibility and impact resistance

  2. Excellent hydrolytic stability

  3. Good weather resistance

  4. Low volatility and improved safety profile

  5. Suitability for high-performance polyurethane systems

4. Conclusion

Dimeryl Diisocyanate (DDI) is a key raw material for high-performance polyurethane formulations. By improving flexibility, water resistance, and long-term durability, DDI-based polyurethanes have been widely adopted in:

  • Elastomers

  • Coatings

  • Adhesives

  • Electronic materials

With increasing market demand for advanced polyurethane materials, Dimeryl Diisocyanate and DDI-based polyurethane systems are becoming increasingly important material choices in high-end industrial applications.

Technical Documentation and Sample Requests

For detailed technical documentation, application guidance, or sample requests for Dimeryl Diisocyanate (CAS No. 68239-06-5), please contact the technical team at Ruifeng Polymer.

We provide responsive support and customized solutions for:

  • Electronic manufacturing

  • Functional materials

  • Polyurethane applications

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