Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is a reactive polysiloxane containing pendant or terminal isocyanate groups (–NCO) attached to the silicone backbone. By combining the flexibility and thermal stability of siloxane chains with the high reactivity of isocyanate functionality, these materials act as reactive intermediates in polyurethane, adhesive, coating, and hybrid polymer systems. Unlike inert dimethyl silicone oils, NCO-functional silicones participate directly in urethane-forming reactions, enabling silicone–organic hybrid networks.
SiliconChemicals™ Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is a high-reactivity polysiloxane engineered with pendant or terminal isocyanate (–NCO) groups. It serves as a reactive silicone intermediate for polyurethane systems, hybrid elastomers, advanced adhesives, and performance coatings. By combining the low surface energy and flexibility of siloxane chains with the strong reactivity of isocyanates, NCO-functional silicone oils enable the formation of silicone–urethane hybrid networks.
| Model Code | NCO Content (%) | NCO Equivalent Weight (g/eq) | Viscosity (25°C, cSt) | Molecular Structure | Reactive Type | Application Positioning |
|---|---|---|---|---|---|---|
| NCO-050-L | 0.5–1.0 | 4,200–8,400 | 100 | Terminal | Low Reactivity | Flexible PU modifier |
| NCO-100-L | 1.0–1.5 | 2,800–4,200 | 300 | Terminal | Medium | Adhesive modifier |
| NCO-150-M | 1.5–2.0 | 2,100–2,800 | 800 | Pendant | Medium | PU coating hybrid |
| NCO-200-M | 2.0–2.5 | 1,700–2,100 | 1,500 | Pendant | Medium-High | Elastomer systems |
| NCO-250-M | 2.5–3.0 | 1,400–1,700 | 3,000 | Pendant | High | Sealant crosslinker |
| NCO-300-H | 3.0–3.5 | 1,200–1,400 | 5,000 | Multi-functional | High | Structural PU |
| NCO-350-H | 3.5–4.0 | 1,050–1,200 | 8,000 | Multi-functional | High | High-modulus systems |
| NCO-400-H | 4.0–4.5 | 930–1,050 | 12,000 | High-density | Very High | Crosslinking grade |
| NCO-500-X | 4.5–5.0 | 840–930 | 15,000 | Multi-functional | Extreme | Specialty elastomers |
| NCO-HT-250 | 2.5–3.0 | 1,400–1,700 | 3,500 | Phenyl-modified | High-temp | Heat-resistant PU |
| NCO-ULV-150 | 1.5–2.0 | 2,100–2,800 | 1,000 | Low volatile | Medium | Electronics grade |
| NCO-OPT-200 | 2.0–2.5 | 1,700–2,100 | 2,000 | Controlled MW | Optical | Transparent coatings |
| NCO-ADH-180 | 1.8–2.2 | 1,900–2,400 | 1,800 | Balanced | Adhesion optimized | PU adhesive |
| NCO-SEAL-300 | 3.0–3.5 | 1,200–1,400 | 6,000 | Crosslink grade | Sealant | Construction PU |
| NCO-FLEX-120 | 1.2–1.8 | 2,300–3,500 | 900 | Flexible backbone | Soft elastomer | Flexible coating |
| NCO-RIGID-400 | 4.0–4.5 | 930–1,050 | 10,000 | High crosslink | Rigid network | High-strength PU |
| NCO-WP-220 | 2.0–2.5 | 1,700–2,100 | 2,200 | Balanced | Waterproof membrane | Roofing |
| NCO-TEXT-100 | 1.0–1.5 | 2,800–4,200 | 400 | Low viscosity | Textile | Fabric finishing |
| NCO-HYB-260 | 2.5–3.0 | 1,400–1,700 | 2,800 | Hybrid | Silicone-PU bridge | Hybrid elastomer |
| NCO-CUSTOM | Adjustable | Custom | 100–20,000+ | Tailored | OEM | System design |
Product List
Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is classified primarily by NCO content, molecular architecture, viscosity, and application orientation. Unlike inert silicone fluids, NCO-functional grades are reactive intermediates designed to integrate silicone performance into polyurethane and hybrid polymer systems.
The core reactive functionality is: −N=C=O-N=C=O
| NCO Level | Typical Range | Functional Behavior | Application Direction |
|---|---|---|---|
| Ultra-Low | 0.5–1.0% | Flexibility modifier | PU soft segment modification |
| Low | 1.0–1.5% | Adhesion enhancement | Coatings & adhesives |
| Medium | 1.5–3.0% | Balanced crosslinking | Hybrid PU systems |
| High | 3.0–4.5% | High crosslink density | Structural sealants |
| Ultra-High | 4.5–6.0%+ | Reactive crosslinker | Specialty elastomers |
Higher NCO % → higher urethane/urea crosslink density potential.
| Structure Type | Description | Typical Use |
|---|---|---|
| Terminal NCO | End-capped silicone chains | Controlled chain extension |
| Pendant NCO | NCO groups along backbone | Hybrid network formation |
| Multi-functional | High-density reactive groups | Crosslinking agent |
| Phenyl-Modified | Heat-resistant backbone | High-temperature PU |
| Low-Volatile Grade | Controlled purity | Electronics & optical |
Architecture directly affects reaction kinetics and final mechanical properties.
| Viscosity Class | Range (cSt) | Processing Orientation |
|---|---|---|
| Low | 100–1,000 | Coating modifiers |
| Medium | 1,000–5,000 | Adhesives & flexible PU |
| High | 5,000–20,000 | Sealants & elastomers |
| Custom MW | Adjustable | OEM system design |
Viscosity impacts dispersion, mixing efficiency, and final film performance.
Improves flexibility, weather resistance, and hydrophobicity.
Enhances bonding to metal, glass, plastic, and mineral substrates.
High NCO content for structural polyurethane systems.
Balances elasticity and durability.
Improves water repellency and UV stability.
Introduces softness and surface modification.
Phenyl-modified backbone for elevated service environments.
Key urethane reaction:
R−NCO+R′−OH−>R−NH−COO−R′R-NCO + R’-OH -> R-NH-COO-R’
| Structural Variable | Functional Impact |
|---|---|
| Higher NCO % | Increased hardness & modulus |
| Lower NCO % | Improved flexibility |
| Silicone backbone length | Weather & UV resistance |
| Multifunctional design | Stronger 3D network |
| Parameter | Coverage Range |
|---|---|
| NCO Content | 0.5% – 6.0%+ |
| Equivalent Weight | 800 – 8,000+ g/eq |
| Viscosity | 100 – 20,000+ cSt |
| Architecture | Terminal / Pendant / Multi-functional |
| Customization | MW & NCO density adjustable |
NCO Silicone Oils are classified based on:
Reactive density + Molecular design + Processing viscosity + Target PU system
They are selected when silicone durability must be integrated into polyurethane matrices, enabling:
SiliconChemicals™ Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is a reactive polysiloxane engineered with controlled isocyanate (–NCO) functionality. It is designed to integrate silicone flexibility, weather resistance, and low surface energy into polyurethane (PU) and hybrid polymer systems through urethane or urea-forming reactions.
This product line serves as a reactive bridge between silicone chemistry and polyurethane technology.
SiliconChemicals™ Isocyanate-Functional Silicone Oil is selected when formulators require:
It is not a simple additive — it is a reactive silicone intermediate for hybrid network engineering.
Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is a reactive polysiloxane containing isocyanate (–NCO) groups attached to a siloxane backbone. The material combines the flexibility and durability of silicone chemistry with the strong reactivity of isocyanate groups, enabling silicone–urethane hybrid network formation.
The structural foundation:
−Si−O−Si−-Si-O-Si-
This backbone provides:
The siloxane chain remains flexible while reactive sites are introduced through functional modification.
The reactive unit:
−N=C=O-N=C=O
This group is highly electrophilic and reacts with nucleophiles such as:
Depending on design, NCO groups may be:
The reactivity of NCO-functional silicone oils is driven by urethane and urea chemistry.
When reacting with polyols:
R−NCO+R′−OH−>R−NH−COO−R′R-NCO + R’-OH -> R-NH-COO-R’
This forms a urethane linkage, integrating silicone segments into polyurethane networks.
Result:
When reacting with amines:
R−NCO+R′−NH2−>R−NH−CO−NH−R′R-NCO + R’-NH2 -> R-NH-CO-NH-R’
Produces strong urea crosslinks used in adhesives and elastomers.
In presence of water:
R−NCO+H2O−>R−NH2+CO2R-NCO + H2O -> R-NH2 + CO2
Followed by secondary urea crosslinking.
This mechanism underpins moisture-curing polyurethane sealants.
| Structural Variable | Functional Impact |
|---|---|
| Higher NCO content | Higher crosslink density |
| Lower NCO content | Increased flexibility |
| Silicone backbone length | Improved weather resistance |
| Multifunctional NCO | 3D network reinforcement |
| Controlled MW | Viscosity & processing control |
The silicone backbone enhances elasticity and durability, while the NCO functionality governs crosslink density and bonding strength.
When incorporated into polyurethane systems:
This leads to:
SiliconChemicals™ NCO Silicone Oil functions as:
It enables the formation of hybrid silicone–urethane networks where the flexibility of siloxane chemistry is chemically bonded into organic polyurethane matrices.
Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is primarily used in polyurethane (PU) and hybrid polymer systems where silicone flexibility, weather resistance, and low surface energy must be chemically integrated into organic matrices.
Its reactivity is based on urethane and urea formation:
R−NCO+R′−OH−>R−NH−COO−R′R-NCO + R’-OH -> R-NH-COO-R’
This enables the formation of silicone–polyurethane hybrid networks.
One of the most important applications.
Used in:
Performance benefits:
Silicone segments migrate to the surface, improving hydrophobicity and durability.
NCO-functional silicone oils enhance:
Applications:
In moisture-curing PU sealants, NCO groups react with ambient moisture:
R−NCO+H2O−>R−NH2+CO2R-NCO + H2O -> R-NH2 + CO2
Used in:
Silicone modification improves weather stability and long-term elasticity.
Silicone-modified PU systems are widely used for:
Advantages:
Used in:
Silicone backbone provides flexibility, while urethane crosslinks provide strength.
Lower NCO-content grades are used in:
The silicone segment improves hand feel and surface performance.
Selected low-volatile grades are used in:
Benefits:
| Industry | Functional Role | Recommended NCO Level |
|---|---|---|
| PU Coatings | Hybrid modifier | Low–Medium |
| Adhesives | Adhesion enhancement | Medium |
| Sealants | Crosslinking | Medium–High |
| Waterproofing | Durability improvement | Medium |
| Structural PU | Crosslink density control | High |
| Textile Finishing | Surface modification | Low |
NCO Silicone Oil is selected when formulators need:
It serves as a reactive silicone bridge for high-performance polyurethane systems, enhancing durability, flexibility, and environmental stability.
Isocyanate-Functional Silicone Oil (NCO Silicone Oil) is used when formulators need to chemically integrate silicone performance into polyurethane (PU) systems. Unlike non-reactive silicone fluids, NCO-functional grades participate directly in urethane chemistry, forming covalent bonds within the polymer network.
The key mechanism is urethane formation:
R−NCO+R′−OH−>R−NH−COO−R′R-NCO + R’-OH -> R-NH-COO-R’
This reaction embeds silicone segments into the PU matrix, creating hybrid silicone–urethane materials.
Silicone oils alone may migrate or bloom.
NCO-functional silicone oils chemically bond into the PU structure.
Result:
Siloxane backbones provide:
When bonded into PU systems, they significantly improve aging resistance.
Silicone segments naturally lower surface tension.
Benefits:
Ideal for coatings and waterproof membranes.
NCO-functional silicone oils improve bonding to:
Through chemical crosslinking and surface interaction enhancement.
By adjusting NCO content, formulators can tune:
Higher NCO → higher crosslink density → stronger network.
Silicone segments act as flexible domains within the PU matrix, improving:
This is critical in construction and automotive applications.
In moisture exposure:
R−NCO+H2O−>R−NH2+CO2R-NCO + H2O -> R-NH2 + CO2
This mechanism supports one-component PU sealants and construction systems.
Use Isocyanate-Functional Silicone Oil (NCO) when you need:
It is not a simple additive — it is a reactive performance modifier for advanced polyurethane engineering.
Selecting the correct NCO-functional silicone oil is not just about viscosity — it is about reactive balance, crosslink density design, molecular architecture, and final performance targets within your polyurethane or hybrid system.
The fundamental design reaction is:
R−NCO+R′−OH−>R−NH−COO−R′R-NCO + R’-OH -> R-NH-COO-R’
Your selection should follow a structured engineering approach.
Determine whether your application is:
Each system requires different NCO density and backbone flexibility.
NCO content directly controls network strength.
| Target Property | Recommended NCO Level |
|---|---|
| Surface modifier | 0.5–1.5% |
| Flexible coating | 1.5–2.5% |
| General adhesive | 2.0–3.0% |
| Structural PU | 3.0–4.5% |
| High-modulus system | 4.5%+ |
Higher NCO → higher crosslink density → increased hardness & modulus.
Proper stoichiometry is critical in polyurethane design.
NCO:OH=1:1(stoichiometricratio)NCO:OH = 1:1 (stoichiometric ratio)
Consider:
Incorrect ratio leads to incomplete cure or brittleness.
| Architecture | When to Use |
|---|---|
| Terminal NCO | Controlled chain extension |
| Pendant NCO | Hybrid network integration |
| Multifunctional | Crosslinking enhancement |
| Phenyl-modified | High-temperature applications |
| Low-volatile | Electronics & optical |
Architecture affects reaction kinetics and phase separation behavior.
| Viscosity Range | Processing Orientation |
|---|---|
| 100–1,000 cSt | Coating modifiers |
| 1,000–5,000 cSt | Adhesives & flexible PU |
| 5,000–20,000 cSt | Sealants & elastomers |
Higher viscosity may require stronger mixing capability.
If your application requires:
In moisture-curing PU systems:
R−NCO+H2O−>R−NH2+CO2R-NCO + H2O -> R-NH2 + CO2
Consider:
| Primary Goal | Recommended Profile |
|---|---|
| Improve flexibility | Low NCO, medium MW |
| Increase adhesion | Medium NCO |
| Enhance durability | Medium NCO, longer silicone backbone |
| Structural reinforcement | High NCO multi-functional |
| Surface hydrophobicity | Low–Medium NCO modifier |
Choose NCO Silicone Oil based on:
Target mechanical performance + Polyol system compatibility + NCO equivalent weight + Processing conditions + Environmental exposure
Correct selection ensures:
Packaging: 500 g / 1 kg / 5 kg / 25 kg / 200 kg drums / 1000L IBC container (Customized packaging is available).
Selecting the right Isocyanate-Functional Silicone Oil (NCO) determines your crosslink density, adhesion strength, flexibility balance, and long-term durability. The correct NCO content and molecular architecture are not minor adjustments — they define your hybrid network performance.
At SiliconChemicals™, we provide precision-engineered NCO-functional silicone oils with:
If you share:
Our technical team will recommend a precisely matched NCO silicone grade to ensure balanced stoichiometry, controlled crosslink density, and stable long-term performance.
SiliconChemicals™
Reactive Silicone Engineering · Hybrid Polymer Design · Global Industrial Supply
Contact us today to discuss your formulation requirements and receive a tailored technical solution.
Disclaimer
“The information provided herein is based on general industry experience and is intended for reference purposes only. Actual performance and optimal usage conditions may vary depending on formulation, processing methods, substrate characteristics, and end-use requirements. Users are responsible for conducting their own tests and evaluations to determine suitability for their specific applications. No warranty, express or implied, is made regarding the completeness, accuracy, or applicability of this information.”
Selecting the right silane coupling agent is only the first step. Achieving optimal performance often requires application-specific evaluation and formulation optimization. Our technical team provides comprehensive support to ensure successful implementation across diverse material systems.
From Standard Supply to Customized Requirements
Built on technical expertise, manufacturing capability, and reliable supply
Supports batch quality verification & application-oriented testing, ensuring consistent performance & reliable product quality.
Stable, scalable manufacturing with standardized processes, supporting both regular supply and bulk industrial demand.
Products are stored under controlled conditions with standardized packaging, enabling efficient order fulfillment and reliable global delivery.
Clear communication and application-focused support, helping customers select suitable products and streamline procurement.
Navigate the complexities of the global Silicone Oil market. This definitive report provides actionable insights, vetted supplier landscapes, and strategic sourcing methodologies to optimize your supply chain in the year ahead.
