Polyurethane Catalyst PC-5 (PMDETA) technical data sheet and typical use levels info

Polyurethane Catalyst PC-5 (PMDETA): A Comprehensive Overview

Introduction

Polyurethane (PU) is a versatile polymer widely used in various applications, ranging from flexible foams and rigid insulation to coatings, adhesives, and elastomers. The formation of polyurethane involves the reaction between a polyol and an isocyanate. This reaction is often slow at room temperature and requires the use of catalysts to achieve desired reaction rates and control the overall process. Polyurethane catalysts are essential components in polyurethane formulations, influencing factors such as gel time, tack-free time, cure rate, and the final properties of the polyurethane product.

Among the vast array of polyurethane catalysts, Polymeric Catalyst-5 (PC-5), chemically known as Pentamethyldiethylenetriamine (PMDETA), stands out as a highly effective tertiary amine catalyst. This article provides a comprehensive overview of PC-5 (PMDETA), exploring its chemical properties, typical use levels, applications, advantages, safety considerations, and a comparison with other common polyurethane catalysts. The structure of PMDETA is shown below:

      CH3   CH3
      |     |
CH3-N-CH2-CH2-N-CH2-CH2-N-CH3

1. Chemical and Physical Properties of PC-5 (PMDETA)

PC-5 (PMDETA) is a clear, colorless to pale yellow liquid with a characteristic amine odor. Its chemical structure features three nitrogen atoms, making it a strong base and an effective catalyst for the polyurethane reaction. The key physical and chemical properties of PC-5 (PMDETA) are summarized in Table 1.

Table 1: Physical and Chemical Properties of PC-5 (PMDETA)

Property	Value	Unit	Source
Chemical Name	Pentamethyldiethylenetriamine	–
CAS Number	3030-47-5	–
Molecular Formula	C9H23N3	–
Molecular Weight	173.30	g/mol
Appearance	Clear, colorless to pale yellow liquid	–
Odor	Amine-like	–
Density (20°C)	0.82-0.83	g/cm³	Supplier Specifications
Viscosity (25°C)	2-3	cP	Supplier Specifications
Boiling Point	195-200	°C	Lide, D.R., ed. CRC Handbook of Chemistry and Physics, 85th Edition. CRC Press. Boca Raton, FL. 2005.
Flash Point (Closed Cup)	71	°C	Supplier Specifications
Refractive Index (20°C)	1.440-1.445	–	Supplier Specifications
Water Solubility	Soluble	–
Amine Value	≥ 950	mg KOH/g	Supplier Specifications

2. Mechanism of Action as a Polyurethane Catalyst

PC-5 (PMDETA) acts as a catalyst by accelerating the reaction between the isocyanate and polyol components. It functions primarily through two key mechanisms:

Proton Abstraction: The tertiary amine group in PMDETA acts as a base, abstracting a proton from the hydroxyl group of the polyol. This increases the nucleophilicity of the polyol, making it more reactive towards the isocyanate.
Isocyanate Activation: PMDETA can also interact directly with the isocyanate group, forming a complex that lowers the activation energy required for the reaction with the polyol. This complexation enhances the electrophilicity of the isocyanate.

The overall catalytic effect of PC-5 (PMDETA) depends on factors such as the specific polyol and isocyanate used, the reaction temperature, and the presence of other additives. It generally favors the gelation reaction (polyol-isocyanate) over the blowing reaction (isocyanate-water), leading to faster cure times and potentially denser polyurethane products.

3. Typical Use Levels of PC-5 (PMDETA)

The optimal use level of PC-5 (PMDETA) in polyurethane formulations varies depending on the specific application and the desired properties of the final product. Factors influencing the dosage include:

Type of Polyol and Isocyanate: Different polyols and isocyanates have varying reactivity, requiring adjustments in catalyst levels.
Reaction Temperature: Higher temperatures generally require lower catalyst concentrations.
Desired Reaction Rate: Faster reactions require higher catalyst concentrations.
Presence of Other Additives: Other additives, such as surfactants and blowing agents, can influence the effectiveness of the catalyst.
Specific Application: Different applications, such as flexible foams, rigid foams, and coatings, have different requirements for catalyst levels.

Table 2: Typical Use Levels of PC-5 (PMDETA) in Various Polyurethane Applications

Application	Typical Use Level (Based on Polyol Weight)	Unit	Notes
Flexible Slabstock Foam	0.05 – 0.3	wt%	Used in conjunction with blowing catalysts (e.g., amine or organotin) to balance gel and blow reactions.
Rigid Foam (Spray/Pour)	0.1 – 0.5	wt%	Promotes rapid cure and good dimensional stability. Often used with other catalysts for specific property optimization.
Microcellular Foam	0.2 – 0.8	wt%	Requires careful control to achieve desired cell structure and density.
Coatings and Adhesives	0.01 – 0.1	wt%	Used to accelerate the curing process and improve adhesion. May require blocking agents to prevent premature reaction.
Elastomers	0.05 – 0.2	wt%	Influences the crosslinking density and mechanical properties of the elastomer.
CASE Applications (Coatings, Adhesives, Sealants, Elastomers)	0.01 – 0.5	wt%	Dosage depends heavily on the specific formulation, desired cure speed, and other performance requirements. Careful optimization is necessary.

Note: The values in Table 2 are guidelines only and should be adjusted based on specific formulation and processing conditions. It is always recommended to perform experimental trials to determine the optimal catalyst level for a given application.

4. Applications of PC-5 (PMDETA)

PC-5 (PMDETA) finds widespread use in various polyurethane applications due to its high catalytic activity and versatility. Some of the key applications include:

Flexible Polyurethane Foams: In flexible slabstock and molded foams, PC-5 (PMDETA) is used in combination with other catalysts, particularly blowing catalysts, to control the balance between the gel and blow reactions. It helps to achieve desired cell structure, density, and mechanical properties. It often works in conjunction with catalysts like DABCO 33-LV or BL-22. Its strong gelling action helps to prevent foam collapse and improve overall foam quality.
Rigid Polyurethane Foams: PC-5 (PMDETA) is widely used in rigid foam applications, such as insulation panels and spray foams, to promote rapid cure and good dimensional stability. Its high catalytic activity enables the use of lower catalyst levels, which can reduce the risk of unwanted side reactions and improve the overall performance of the foam. It is often used in conjunction with potassium acetate catalysts to optimize reactivity and dimensional stability.
Microcellular Polyurethane Foams: In microcellular foam applications, PC-5 (PMDETA) is used to control the cell size and density. Careful control of the catalyst level is crucial to achieve the desired microcellular structure.
Polyurethane Coatings and Adhesives: PC-5 (PMDETA) is used in polyurethane coatings and adhesives to accelerate the curing process and improve adhesion to various substrates. It can be used in both solvent-based and water-based formulations. The low levels required minimize their impact on the coating’s final properties.
Polyurethane Elastomers: PC-5 (PMDETA) is used in polyurethane elastomers to influence the crosslinking density and mechanical properties of the elastomer. It can be used to tailor the hardness, tensile strength, and elongation of the elastomer.
CASE Applications (Coatings, Adhesives, Sealants, Elastomers): PC-5 is a versatile catalyst that can be used across various CASE applications. It helps to accelerate the cure speed and improve the overall performance of the final product.

5. Advantages of Using PC-5 (PMDETA) as a Polyurethane Catalyst

PC-5 (PMDETA) offers several advantages over other polyurethane catalysts, including:

High Catalytic Activity: PC-5 (PMDETA) is a highly active catalyst, allowing for faster reaction rates and lower catalyst concentrations.
Versatility: PC-5 (PMDETA) can be used in a wide range of polyurethane applications.
Good Solubility: PC-5 (PMDETA) is soluble in most common polyols and isocyanates, facilitating easy incorporation into polyurethane formulations.
Relatively Low Odor: Compared to some other amine catalysts, PC-5 (PMDETA) has a relatively mild odor, making it more pleasant to work with.
Improved Processing: The strong gelling action can improve processing characteristics, especially in foam applications, preventing collapse and improving cell structure.

6. Safety Considerations and Handling Precautions

While PC-5 (PMDETA) is a valuable polyurethane catalyst, it is essential to handle it with care and follow appropriate safety precautions.

Toxicity: PC-5 (PMDETA) is considered moderately toxic by ingestion, skin contact, and inhalation.
Irritation: PC-5 (PMDETA) can cause skin and eye irritation. Direct contact should be avoided.
Flammability: PC-5 (PMDETA) is flammable and should be kept away from heat, sparks, and open flames.
Handling Precautions:
- Wear appropriate personal protective equipment (PPE), including gloves, safety glasses, and a respirator, when handling PC-5 (PMDETA).
- Work in a well-ventilated area to minimize exposure to vapors.
- Avoid contact with skin, eyes, and clothing.
- Wash thoroughly after handling.
- Store in a tightly closed container in a cool, dry, and well-ventilated area.
- Keep away from incompatible materials, such as strong acids and oxidizing agents.
First Aid Measures:
- Eye Contact: Immediately flush with plenty of water for at least 15 minutes and seek medical attention.
- Skin Contact: Wash with soap and water. Remove contaminated clothing and shoes. If irritation persists, seek medical attention.
- Inhalation: Remove to fresh air. If breathing is difficult, administer oxygen. If not breathing, give artificial respiration. Seek medical attention.
- Ingestion: Do not induce vomiting. Rinse mouth with water. Seek medical attention immediately.

Table 3: Safety Data for PC-5 (PMDETA)

Hazard	Description
Acute Toxicity (Oral)	Category 4: Harmful if swallowed.
Acute Toxicity (Dermal)	Category 4: Harmful in contact with skin.
Skin Corrosion/Irritation	Category 2: Causes skin irritation.
Serious Eye Damage/Eye Irritation	Category 2A: Causes serious eye irritation.
Specific Target Organ Toxicity (Single Exposure)	Category 3: May cause respiratory irritation.
Flammable Liquids	Category 3: Flammable liquid and vapor.

Note: Always consult the Safety Data Sheet (SDS) for the most up-to-date and comprehensive safety information.

7. Comparison with Other Polyurethane Catalysts

PC-5 (PMDETA) is just one of many polyurethane catalysts available. Other common catalysts include tertiary amines such as triethylenediamine (TEDA or DABCO), dimethylcyclohexylamine (DMCHA), and organotin compounds such as dibutyltin dilaurate (DBTDL). Table 4 provides a comparison of PC-5 (PMDETA) with some of these other catalysts.

Table 4: Comparison of PC-5 (PMDETA) with Other Common Polyurethane Catalysts

Catalyst	Chemical Class	Relative Activity	Gel/Blow Selectivity	Advantages	Disadvantages	Typical Applications
PC-5 (PMDETA)	Tertiary Amine	High	Gel > Blow	High activity, versatile, relatively low odor, good solubility.	Can cause skin and eye irritation, strong gelling action may require balancing with blowing catalyst.	Flexible foams, rigid foams, microcellular foams, coatings, adhesives, elastomers.
Triethylenediamine (TEDA/DABCO)	Tertiary Amine	High	Gel = Blow	High activity, widely used, good balance between gel and blow reactions.	Can cause skin and eye irritation, strong odor.	Flexible foams, rigid foams, coatings, adhesives, elastomers.
Dimethylcyclohexylamine (DMCHA)	Tertiary Amine	Moderate	Blow > Gel	Promotes blowing reaction, useful for low-density foams.	Strong odor, can cause skin and eye irritation.	Flexible foams (blowing catalyst), spray foams.
Dibutyltin Dilaurate (DBTDL)	Organotin	Very High	Gel > Blow	Very high activity, promotes rapid cure, good for coatings and elastomers.	Toxic, environmental concerns, sensitive to hydrolysis.	Coatings, adhesives, elastomers.
DABCO 33-LV	Tertiary Amine Solution	High	Gel = Blow	A solution of TEDA that is easier to handle and disperse, good balance between gel and blow reactions.	Can cause skin and eye irritation, strong odor.	Flexible foams, rigid foams, coatings, adhesives, elastomers.

The choice of catalyst depends on the specific requirements of the polyurethane formulation and the desired properties of the final product. PC-5 (PMDETA) is a good choice when high catalytic activity and a strong gelling effect are desired, but it may need to be used in combination with other catalysts to achieve the optimal balance of properties.

8. Market Availability and Suppliers

PC-5 (PMDETA) is commercially available from numerous suppliers worldwide. These suppliers offer PC-5 (PMDETA) in various grades and packaging options to meet the needs of different applications. Some of the major suppliers include:

Evonik Industries
Huntsman Corporation
Air Products and Chemicals, Inc.
Momentive Performance Materials
Tosoh Corporation

It’s crucial to choose a reputable supplier and ensure the PC-5 (PMDETA) meets the required specifications for the intended application.

9. Future Trends and Development

The polyurethane industry is constantly evolving, with ongoing research and development focused on improving the performance, sustainability, and safety of polyurethane materials. Future trends and development related to PC-5 (PMDETA) and other polyurethane catalysts include:

Development of new and improved amine catalysts: Research is focused on developing amine catalysts with lower odor, reduced toxicity, and improved performance characteristics.
Development of bio-based catalysts: Efforts are underway to develop polyurethane catalysts derived from renewable resources to reduce the environmental impact of polyurethane production.
Development of catalyst blends: Catalyst blends are being developed to provide synergistic effects and optimize the performance of polyurethane formulations.
Development of blocked catalysts: Blocked catalysts are being developed to provide better control over the reaction process and prevent premature reaction.
Improved understanding of catalyst mechanisms: Research is ongoing to improve the understanding of the mechanisms of action of polyurethane catalysts, which will lead to the development of more efficient and effective catalysts.

Conclusion

PC-5 (PMDETA) is a highly effective and versatile tertiary amine catalyst widely used in the polyurethane industry. Its high catalytic activity, good solubility, and relatively low odor make it a valuable component in various polyurethane formulations. Understanding its properties, applications, safety considerations, and comparison with other catalysts is essential for formulators to optimize polyurethane systems and achieve desired product performance. As the polyurethane industry continues to evolve, ongoing research and development will undoubtedly lead to further advancements in polyurethane catalyst technology, including improvements in the performance, sustainability, and safety of catalysts like PC-5 (PMDETA).

Literature Sources:

Oertel, G. (Ed.). (1985). Polyurethane Handbook: Chemistry-Raw Materials-Processing-Application-Properties. Hanser Gardner Publications.
Woods, G. (1990). The ICI Polyurethanes Book. John Wiley & Sons.
Randall, D., & Lee, S. (2002). The Polyurethanes Book. John Wiley & Sons.
Ashida, K. (2006). Polyurethane and Related Foams: Chemistry and Technology. CRC Press.
Hepburn, C. (1991). Polyurethane Elastomers. Springer Science & Business Media.
Ulrich, H. (1996). Introduction to Industrial Polymers. Hanser Gardner Publications.
Lide, D.R., ed. CRC Handbook of Chemistry and Physics, 85th Edition. CRC Press. Boca Raton, FL. 2005.
Supplier Specifications (Consult specific supplier’s technical data sheets for the most accurate values).
Various Safety Data Sheets (SDS) for PMDETA from different suppliers. Always consult the specific SDS for the product being used.