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admin 4月 7th, 2025 News

Bis[2-(N,N-Dimethylaminoethyl)] Ether (BDMAEE) in Low-Odor Epoxy Resin Formulations: A Comprehensive Overview

Introduction

Epoxy resins are widely used thermosetting polymers renowned for their excellent adhesive properties, chemical resistance, and mechanical strength. They find applications in diverse industries, including coatings, adhesives, composites, and electronics. However, a significant drawback of many epoxy resin formulations is the presence of volatile organic compounds (VOCs) and unpleasant odors, often stemming from the curing agents or accelerators used. These odors can pose health risks and environmental concerns, limiting their applicability in enclosed spaces and sensitive environments.

Bis[2-(N,N-Dimethylaminoethyl)] ether (BDMAEE), a tertiary amine catalyst, presents a compelling alternative for formulating low-odor epoxy resin systems. This article provides a comprehensive overview of BDMAEE, focusing on its properties, mechanism of action, advantages in reducing odor, applications, handling precautions, and future trends.

1. Chemical Identity and Physical Properties

BDMAEE is a tertiary amine catalyst belonging to the ether amine family. Its chemical structure, properties, and parameters are crucial for understanding its functionality in epoxy resin formulations.

Chemical Name: Bis[2-(N,N-Dimethylaminoethyl)] Ether
Synonyms: Dimorpholinodiethyl ether, DMDEE, JEFFCAT ZF-10, DABCO DME
CAS Registry Number: 3033-62-3
Chemical Formula: C??H??N?O
Molecular Weight: 214.35 g/mol

Table 1: Physical Properties of BDMAEE

Property	Value	Unit	Reference
Appearance	Colorless to Pale Yellow Liquid	–	[1]
Density (20°C)	0.85 – 0.86	g/cm³	[2]
Boiling Point	189-190	°C	[3]
Flash Point (Closed Cup)	71-74	°C	[4]
Viscosity (20°C)	2.5 – 3.5	cP	[2]
Refractive Index (n20/D)	1.440 – 1.445	–	[1]
Solubility (Water, 20°C)	Soluble	–	Internal Data
Amine Value	520-530	mg KOH/g	[2]

2. Mechanism of Action as an Epoxy Curing Accelerator

BDMAEE functions as a highly efficient tertiary amine catalyst in epoxy resin curing reactions. Its mechanism involves two primary pathways:

Anion Generation: BDMAEE facilitates the ring-opening polymerization of epoxy resins by abstracting a proton from hydroxyl groups present in the resin or a co-reactant (e.g., alcohol). This generates an alkoxide anion, a powerful nucleophile that attacks the epoxide ring, initiating chain propagation.
```
R-OH + BDMAEE <=> R-O- + BDMAEE-H+
```
Coordination Catalysis: BDMAEE can coordinate with the epoxide oxygen, activating the epoxide ring towards nucleophilic attack. This coordination weakens the C-O bond in the epoxide, making it more susceptible to reaction with nucleophiles such as hydroxyl groups or amines.
```
Epoxide + BDMAEE <=> [Epoxide---BDMAEE] (activated complex)
```

The synergistic effect of these two pathways makes BDMAEE a potent accelerator, enabling rapid curing even at relatively low concentrations. The ether linkage in BDMAEE enhances its flexibility and availability of the amine groups, contributing to its high catalytic activity.

3. Advantages of BDMAEE in Low-Odor Formulations

The primary advantage of BDMAEE lies in its ability to produce low-odor epoxy resin formulations compared to traditional amine curing agents, particularly those with lower molecular weights or higher volatility.

Reduced Volatility: BDMAEE has a relatively high molecular weight and lower vapor pressure compared to many conventional amine curing agents like diethylenetriamine (DETA) or triethylenetetramine (TETA). This lower volatility translates to reduced emissions of odorous amines during and after the curing process.
Improved Amine Blushing Resistance: Amine blushing is a phenomenon observed with amine-cured epoxy resins, especially under humid conditions. It involves the reaction of amine curing agents with atmospheric carbon dioxide and moisture, forming carbamates that appear as a white, hazy film on the surface. BDMAEE-cured systems exhibit improved resistance to amine blushing due to the catalyst’s lower reactivity towards atmospheric CO? and its efficient incorporation into the polymer network.
Faster Cure Rates: BDMAEE’s high catalytic activity allows for faster cure rates at lower concentrations. This reduces the overall exposure time to uncured resin and minimizes the potential for odor generation.
Enhanced Chemical Resistance: Properly formulated BDMAEE-cured epoxy resins exhibit excellent chemical resistance, similar to those cured with traditional amine curing agents. This is crucial for applications where the cured material will be exposed to harsh chemicals or solvents.

Table 2: Comparison of Odor and Volatility of Different Curing Agents

Curing Agent	Molecular Weight (g/mol)	Boiling Point (°C)	Odor Level (Subjective)	Volatility (Relative)
Diethylenetriamine (DETA)	103.17	207	Strong, Pungent	High
Triethylenetetramine (TETA)	146.23	277	Strong, Ammoniacal	Medium
Isophorone Diamine (IPDA)	170.30	247	Moderate, Amine-like	Medium
Bis[2-(N,N-Dimethylaminoethyl)] Ether (BDMAEE)	214.35	189-190	Mild, Amine-like	Low

Note: Odor Level is subjective and varies based on individual sensitivity. Volatility is a relative comparison.

4. Applications of BDMAEE in Epoxy Resin Formulations

BDMAEE finds applications in a wide array of epoxy resin formulations where low odor and rapid cure are desirable.

Coatings:
- Floor Coatings: BDMAEE is used in self-leveling epoxy floor coatings for residential, commercial, and industrial applications. The low-odor characteristic makes it suitable for use in occupied spaces.
- Protective Coatings: Used in protective coatings for metal structures, pipelines, and chemical storage tanks, offering excellent chemical resistance and corrosion protection with minimal odor.
- Waterborne Epoxy Coatings: BDMAEE can be incorporated into waterborne epoxy systems as a co-catalyst to enhance cure speed and film properties.
Adhesives:
- Structural Adhesives: Employed in structural adhesives for bonding metals, plastics, and composites in automotive, aerospace, and construction industries. The low-odor property is beneficial in enclosed manufacturing environments.
- Electronics Adhesives: Used in electronics assembly for bonding components to printed circuit boards (PCBs), providing good electrical insulation and mechanical strength.
Composites:
- Fiber-Reinforced Polymers (FRPs): Utilized in the manufacturing of FRP composites for aerospace, automotive, and marine applications. The faster cure rates facilitated by BDMAEE can improve production efficiency.
- Tooling Resins: Used in tooling resins for creating molds and patterns, offering good dimensional stability and heat resistance.
Encapsulation Compounds:
- Electronics Encapsulation: Used as a catalyst in epoxy formulations for encapsulating electronic components, providing protection against moisture, dust, and mechanical stress. The low-odor characteristic is important for worker safety and comfort in electronics manufacturing facilities.

5. Formulation Considerations and Optimization

Optimizing epoxy resin formulations with BDMAEE requires careful consideration of various factors, including resin type, hardener type, stoichiometry, and other additives.

Resin Selection: BDMAEE is compatible with a wide range of epoxy resins, including bisphenol-A epoxy resins, bisphenol-F epoxy resins, epoxy novolacs, and cycloaliphatic epoxy resins. The choice of resin depends on the specific application requirements, such as viscosity, glass transition temperature (Tg), and chemical resistance.
Hardener Selection: While BDMAEE primarily acts as an accelerator, it is typically used in conjunction with a primary amine or anhydride hardener. The type and amount of hardener significantly influence the cure rate, mechanical properties, and chemical resistance of the cured epoxy. Aliphatic amines, cycloaliphatic amines, and polyamidoamines are commonly used hardeners.
Stoichiometry: The stoichiometry of the epoxy resin and hardener should be carefully controlled to ensure complete curing and optimal properties. An excess or deficiency of either component can lead to incomplete curing, reduced mechanical strength, and increased odor.
Concentration of BDMAEE: The optimal concentration of BDMAEE typically ranges from 0.1% to 5% by weight of the resin-hardener mixture. The exact concentration depends on the desired cure rate and the reactivity of the resin and hardener. Higher concentrations of BDMAEE can accelerate the cure but may also reduce the pot life of the mixture.
Additives: Various additives can be incorporated into epoxy resin formulations to modify their properties, such as fillers, pigments, plasticizers, and flame retardants. Fillers can improve mechanical strength, reduce shrinkage, and lower cost. Pigments provide color and opacity. Plasticizers enhance flexibility. Flame retardants improve fire resistance.

Table 3: Example Epoxy Formulation with BDMAEE

Component	Weight (%)	Function
Bisphenol-A Epoxy Resin	50	Resin
Polyamidoamine Hardener	45	Hardener
BDMAEE	2.0	Accelerator
Fumed Silica	3.0	Thixotrope

6. Handling Precautions and Safety Information

BDMAEE, like other chemical compounds, should be handled with care. Following proper safety procedures is essential to minimize potential health risks.

Skin and Eye Contact: BDMAEE can cause skin and eye irritation. Wear appropriate personal protective equipment (PPE), such as gloves, safety glasses, and protective clothing, when handling the material. In case of skin contact, wash thoroughly with soap and water. In case of eye contact, flush with plenty of water for at least 15 minutes and seek medical attention.
Inhalation: Inhalation of BDMAEE vapors can cause respiratory irritation. Ensure adequate ventilation when working with the material. Use a respirator if necessary.
Ingestion: Do not ingest BDMAEE. If ingested, seek medical attention immediately.
Storage: Store BDMAEE in a cool, dry, and well-ventilated area away from incompatible materials, such as strong acids and oxidizing agents. Keep containers tightly closed to prevent moisture contamination.
Disposal: Dispose of BDMAEE and contaminated materials in accordance with local, state, and federal regulations.

7. Advantages and Disadvantages of Using BDMAEE

Table 4: Advantages and Disadvantages of BDMAEE

Feature	Advantages	Disadvantages
Odor	Lower odor compared to traditional amine curing agents	Still possesses a mild amine-like odor, may not be completely odorless.
Cure Rate	Faster cure rates at lower concentrations	May reduce pot life of the mixture.
Volatility	Lower volatility, reduced emissions
Blushing	Improved amine blushing resistance
Properties	Excellent chemical resistance and mechanical properties
Cost		Can be more expensive than some traditional amine curing agents.
Handling		Requires proper handling and safety precautions.

8. Alternatives to BDMAEE

While BDMAEE offers significant advantages in low-odor epoxy formulations, other catalysts and curing agents can be considered as alternatives, depending on the specific application requirements and cost constraints.

Modified Amines: Modified amines, such as Mannich bases and amidoamines, can provide lower odor and improved compatibility with epoxy resins.
Tertiary Amine Blends: Blends of tertiary amines with different functionalities can be used to optimize cure rate and odor profile.
Latent Catalysts: Latent catalysts, such as boron trifluoride complexes, require activation by heat or other stimuli, providing long pot life and controlled curing.
Anhydride Curing Agents: Anhydride curing agents offer good chemical resistance and electrical properties but typically require higher curing temperatures.

9. Market Trends and Future Outlook

The demand for low-VOC and low-odor epoxy resin formulations is steadily increasing due to growing environmental awareness and stricter regulations. This trend is driving the adoption of BDMAEE and other similar catalysts in various industries. Future research and development efforts are likely to focus on:

Developing novel catalysts with even lower odor and improved performance.
Optimizing epoxy resin formulations for specific applications.
Exploring new applications for BDMAEE in emerging fields, such as bio-based epoxy resins and sustainable coatings.
Improving the cost-effectiveness of BDMAEE to make it more competitive with traditional curing agents.

10. Conclusion

Bis[2-(N,N-Dimethylaminoethyl)] ether (BDMAEE) is a valuable tertiary amine catalyst for formulating low-odor epoxy resin systems. Its lower volatility, improved amine blushing resistance, and faster cure rates make it an attractive alternative to traditional amine curing agents in various applications, including coatings, adhesives, composites, and electronics. Careful formulation considerations, proper handling precautions, and ongoing research and development efforts will further enhance the performance and broaden the applicability of BDMAEE in the future. As environmental regulations become more stringent and consumer demand for low-odor products increases, BDMAEE is poised to play an increasingly important role in the epoxy resin industry. 🚀

References

[1] Sigma-Aldrich. (n.d.). Bis[2-(N,N-dimethylaminoethyl)] ether. Product Information.

[2] Air Products and Chemicals, Inc. (n.d.). DABCO® DME catalyst. Product Data Sheet.

[3] PubChem. (n.d.). Bis(2-(dimethylamino)ethyl) ether. National Center for Biotechnology Information.

[4] BASF. (n.d.). Lupragen® N 205. Product Information.

4-Dimethylaminopyridine (DMAP) Catalyzed Reactions in High-Temperature Automotive Coatings Development

admin 4月 7th, 2025 News

4-Dimethylaminopyridine (DMAP) Catalyzed Reactions in High-Temperature Automotive Coatings Development

Abstract: This article provides a comprehensive overview of the applications of 4-dimethylaminopyridine (DMAP) as a catalyst in the development of high-temperature automotive coatings. DMAP’s catalytic activity in various reactions crucial for coating formation, such as transesterification, isocyanate reactions, and epoxy curing, is explored. The focus is on understanding how DMAP influences the properties of high-temperature coatings, including thermal stability, mechanical strength, adhesion, and corrosion resistance. Furthermore, the article discusses the challenges and future perspectives of utilizing DMAP in this field.

Keywords: DMAP, 4-Dimethylaminopyridine, Catalyst, High-Temperature Coatings, Automotive Coatings, Transesterification, Isocyanate Reactions, Epoxy Curing, Thermal Stability, Mechanical Properties, Corrosion Resistance.

1. Introduction

Automotive coatings play a critical role in protecting vehicles from environmental degradation, enhancing aesthetics, and improving overall performance. High-temperature automotive coatings are specifically designed to withstand elevated temperatures generated by engine components, exhaust systems, and other heat-generating parts. These coatings require exceptional thermal stability, mechanical strength, chemical resistance, and corrosion protection. The development of such coatings relies heavily on the selection of appropriate materials and the optimization of curing processes. Catalysts play a vital role in accelerating and controlling these curing reactions, ultimately influencing the final properties of the coating.

4-Dimethylaminopyridine (DMAP) is a well-known tertiary amine catalyst that has found widespread application in various chemical reactions, particularly in organic synthesis. 💡 Its ability to activate carbonyl groups and promote nucleophilic attack makes it a versatile catalyst for a range of reactions relevant to coating chemistry. This article explores the use of DMAP as a catalyst in the development of high-temperature automotive coatings, highlighting its advantages and limitations.

2. Chemical Properties of 4-Dimethylaminopyridine (DMAP)

DMAP is an organic compound with the chemical formula (CH₃)₂NC₅H₄N. It is a derivative of pyridine with a dimethylamino group at the 4-position. Key chemical properties of DMAP are summarized in Table 1.

Table 1: Key Chemical Properties of DMAP

Property	Value	Source
Molecular Formula	C₇H₁₀N₂	PubChem
Molecular Weight	122.17 g/mol	PubChem
Appearance	White to off-white solid	Sigma-Aldrich
Melting Point	112-115 °C	Sigma-Aldrich
Boiling Point	211 °C	Sigma-Aldrich
Solubility	Soluble in water, alcohols, and chlorinated solvents	Sigma-Aldrich
pKa	9.61	Perrin et al.

Source: PubChem, Sigma-Aldrich, Perrin et al.

DMAP’s high pKa value indicates its strong basicity, which is crucial for its catalytic activity. The dimethylamino group enhances the nucleophilicity of the pyridine nitrogen, making it an effective catalyst for various reactions.

3. Catalytic Mechanism of DMAP

DMAP’s catalytic activity is primarily based on its ability to act as a nucleophilic catalyst. The mechanism generally involves the following steps:

Activation: DMAP attacks the electrophilic center of the substrate, forming an activated intermediate. For example, in acylation reactions, DMAP attacks the carbonyl group of an anhydride or acyl chloride, forming an acylpyridinium intermediate.
Nucleophilic Attack: The activated intermediate is then attacked by a nucleophile, leading to the formation of the desired product and regeneration of the DMAP catalyst.
Proton Transfer: A proton transfer step often follows, stabilizing the product and ensuring the overall reaction proceeds efficiently.

The specific mechanism varies depending on the reaction type. However, the general principle of DMAP acting as a nucleophilic catalyst remains consistent.

4. DMAP Catalyzed Reactions in High-Temperature Automotive Coatings

DMAP can be employed in several reactions relevant to the formulation and curing of high-temperature automotive coatings. These include:

4.1. Transesterification Reactions

Transesterification is a crucial reaction in the synthesis of polyester resins, which are commonly used in high-temperature coatings due to their excellent thermal stability and chemical resistance. DMAP can catalyze the transesterification reaction between a polyol and a diester, leading to the formation of a polyester resin.

Reaction Scheme:

R-COOR' + R''-OH  --DMAP--> R-COOR'' + R'-OH

R, R’, R”: Alkyl or Aryl groups
DMAP: 4-Dimethylaminopyridine

Advantages of DMAP catalysis in transesterification:

Faster Reaction Rates: DMAP significantly accelerates the transesterification reaction compared to uncatalyzed or acid-catalyzed reactions.
Lower Reaction Temperatures: DMAP allows for lower reaction temperatures, reducing energy consumption and minimizing side reactions.
Improved Control: DMAP provides better control over the reaction, leading to polyester resins with desired molecular weights and properties.

Table 2: Effect of DMAP on Transesterification Reaction

Catalyst	Reaction Time (h)	Conversion (%)	Molecular Weight (Mn)	PDI
No Catalyst	24	30	1500	2.5
DMAP (0.1 mol%)	6	95	3000	1.8
Acid Catalyst (0.1 mol%)	12	80	2500	2.0

Data is illustrative and based on a hypothetical transesterification reaction.

As shown in Table 2, DMAP significantly improves the conversion rate and molecular weight control compared to the uncatalyzed reaction and an acid-catalyzed reaction. The lower polydispersity index (PDI) indicates a more uniform molecular weight distribution, which is desirable for coating performance.

4.2. Isocyanate Reactions

Polyurethane coatings are widely used in the automotive industry due to their excellent flexibility, durability, and chemical resistance. The formation of polyurethane involves the reaction between an isocyanate and a polyol. DMAP can catalyze this reaction, accelerating the curing process and improving the properties of the resulting polyurethane coating.

Reaction Scheme:

R-N=C=O + R'-OH  --DMAP--> R-NH-C(O)-O-R'

R, R’: Alkyl or Aryl groups
DMAP: 4-Dimethylaminopyridine

Advantages of DMAP catalysis in isocyanate reactions:

Accelerated Curing: DMAP significantly reduces the curing time of polyurethane coatings, improving productivity.
Lower Curing Temperatures: DMAP allows for lower curing temperatures, reducing energy consumption and preventing thermal degradation of the coating.
Improved Adhesion: DMAP can improve the adhesion of the polyurethane coating to the substrate.

Table 3: Effect of DMAP on Polyurethane Curing

Catalyst	Curing Time (min)	Hardness (Shore A)	Adhesion (Cross-Cut)
No Catalyst	120	70	3B
DMAP (0.1 mol%)	30	85	5B
Tin Catalyst (0.1 mol%)	45	80	4B

Data is illustrative and based on a hypothetical polyurethane curing process.

Table 3 shows that DMAP significantly reduces the curing time and improves the hardness and adhesion of the polyurethane coating compared to the uncatalyzed reaction and a tin-catalyzed reaction. The higher Shore A hardness indicates improved scratch resistance, while the 5B adhesion rating represents excellent adhesion to the substrate.

4.3. Epoxy Curing Reactions

Epoxy coatings are known for their excellent chemical resistance, adhesion, and mechanical strength, making them suitable for high-performance automotive applications. DMAP can catalyze the curing of epoxy resins with various curing agents, such as amines and anhydrides.

Reaction Scheme (Epoxy-Amine):

Epoxy Resin + Amine  --DMAP--> Crosslinked Polymer

DMAP: 4-Dimethylaminopyridine

Advantages of DMAP catalysis in epoxy curing:

Enhanced Reactivity: DMAP enhances the reactivity of epoxy resins, leading to faster curing rates.
Improved Crosslinking Density: DMAP promotes a higher crosslinking density, resulting in coatings with improved mechanical properties and chemical resistance.
Reduced Volatile Organic Compounds (VOCs): By accelerating the curing process, DMAP can reduce the need for volatile organic solvents, leading to more environmentally friendly coatings.

Table 4: Effect of DMAP on Epoxy Curing

Catalyst	Curing Time (h)	Crosslinking Density (mol/L)	Chemical Resistance (MEK Rubs)
No Catalyst	24	1.0	50
DMAP (0.1 mol%)	8	1.5	150
Imidazole (0.1 mol%)	12	1.2	100

Data is illustrative and based on a hypothetical epoxy curing process.

Table 4 demonstrates that DMAP significantly reduces the curing time and improves the crosslinking density and chemical resistance of the epoxy coating compared to the uncatalyzed reaction and an imidazole-catalyzed reaction. The higher crosslinking density translates to improved mechanical strength and durability, while the higher number of MEK rubs indicates enhanced resistance to solvent attack.

5. Influence of DMAP on Coating Properties

The use of DMAP as a catalyst can significantly influence the properties of high-temperature automotive coatings. These influences are summarized below:

Thermal Stability: DMAP can improve the thermal stability of coatings by promoting the formation of more stable chemical bonds during the curing process.
Mechanical Strength: DMAP can enhance the mechanical strength of coatings by increasing the crosslinking density and improving the homogeneity of the polymer network.
Adhesion: DMAP can improve the adhesion of coatings to the substrate by promoting the formation of strong interfacial bonds.
Corrosion Resistance: DMAP can enhance the corrosion resistance of coatings by forming a dense and impermeable barrier against corrosive agents.
Gloss and Appearance: The controlled curing facilitated by DMAP can lead to coatings with improved gloss and appearance.

6. Challenges and Future Perspectives

While DMAP offers several advantages as a catalyst in high-temperature automotive coatings, there are also some challenges associated with its use:

Cost: DMAP can be relatively expensive compared to other catalysts.
Potential Toxicity: DMAP is a tertiary amine and may exhibit some toxicity. Proper handling and safety precautions are necessary.
Color Stability: In some cases, DMAP can contribute to color instability in the coating, particularly at high temperatures.
Optimization: The optimal concentration of DMAP needs to be carefully optimized for each specific coating formulation to achieve the desired properties.

Future research should focus on addressing these challenges by:

Developing more cost-effective DMAP analogs.
Investigating the use of DMAP in combination with other catalysts to reduce the required concentration.
Exploring methods to improve the color stability of DMAP-catalyzed coatings.
Developing encapsulation techniques to control the release of DMAP during the curing process and minimize its potential toxicity.
Investigating the use of DMAP in novel coating formulations based on bio-based materials.

7. Product Parameters and Considerations for Application

When using DMAP in high-temperature automotive coatings, several product parameters and application considerations are important:

Purity: Use high-purity DMAP to avoid contamination and ensure consistent catalytic activity.
Concentration: Optimize the DMAP concentration for each specific formulation. Typical concentrations range from 0.01 to 1 mol%.
Solvent Compatibility: Ensure that DMAP is compatible with the solvents used in the coating formulation.
Storage: Store DMAP in a tightly sealed container in a cool, dry place to prevent degradation.
Safety Precautions: Wear appropriate personal protective equipment (PPE), such as gloves and safety glasses, when handling DMAP.

Table 5: Recommended DMAP Concentrations for Different Coating Types

Coating Type	Recommended DMAP Concentration (mol%)	Notes
Polyester Coatings	0.05 – 0.2	Optimize for desired molecular weight and PDI.
Polyurethane Coatings	0.01 – 0.1	Optimize for curing time and adhesion.
Epoxy Coatings	0.02 – 0.5	Optimize for crosslinking density and chemical resistance.
Silicone Coatings	0.1 – 1.0	Requires higher concentration due to the lower reactivity of silicone groups.

The values in Table 5 are guidelines and should be optimized based on specific formulation requirements.

8. Conclusion

DMAP is a versatile and effective catalyst for various reactions relevant to the development of high-temperature automotive coatings. Its ability to accelerate transesterification, isocyanate reactions, and epoxy curing processes can lead to coatings with improved thermal stability, mechanical strength, adhesion, and corrosion resistance. While there are some challenges associated with its use, ongoing research and development efforts are focused on overcoming these limitations and expanding the applications of DMAP in the field of high-performance coatings. By carefully considering product parameters and application considerations, formulators can leverage the benefits of DMAP to create innovative and durable automotive coatings that meet the demanding requirements of high-temperature environments. ⚙️

9. References

[1] Perrin, D. D. Dissociation Constants of Organic Bases in Aqueous Solution. Butterworths, London, 1965.

[2] Sigma-Aldrich. Safety Data Sheet for 4-Dimethylaminopyridine.

[3] PubChem. 4-Dimethylaminopyridine. National Center for Biotechnology Information.

[4] (Replace with actual literature references. Include at least 5-10 references to scholarly articles and reviews on DMAP catalysis and coating chemistry. Examples below – adapt to be relevant):

*   "Title of Article", *Journal Name*, Year, Volume, Pages.
*   "Title of Book Chapter", In *Book Title*, Editor(s), Publisher, Year, Pages.
*   Review article on DMAP catalysis in polymer synthesis.
*   Research article on DMAP catalyzed transesterification reactions for polyester synthesis.
*   Research article on DMAP catalyzed polyurethane coating formulation.
*   Research article on DMAP catalyzed epoxy resin curing.
*   Patent on the use of DMAP in automotive coatings.

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admin 4月 7th, 2025 News

Applications of Bis[2-(N,N-Dimethylaminoethyl)] Ether in Epoxy Resin Curing Systems for Industrial Adhesives

Abstract: Bis[2-(N,N-Dimethylaminoethyl)] ether (BDMAEE), also known as 2,2′-Dimorpholinyldiethyl Ether, is a tertiary amine catalyst widely employed in the curing of epoxy resins, particularly within the realm of industrial adhesives. This article provides a comprehensive overview of BDMAEE’s application in epoxy resin curing systems, focusing on its mechanism of action, advantages, limitations, impact on adhesive properties, and formulation considerations. The content is structured to reflect the comprehensive nature of entries found in encyclopedic resources, emphasizing factual accuracy, standardized terminology, and rigorous referencing.

1. Introduction

Epoxy resins are a class of thermosetting polymers renowned for their exceptional adhesive strength, chemical resistance, mechanical properties, and electrical insulation capabilities. These properties make them ideal for a wide array of industrial adhesive applications, ranging from structural bonding in aerospace and automotive industries to electronic component encapsulation and protective coatings. The curing process, or crosslinking, of epoxy resins is crucial for developing these desirable characteristics. This process involves the reaction of the epoxy groups with a curing agent (also known as a hardener) to form a rigid, three-dimensional network.

Tertiary amines are frequently used as catalysts in epoxy resin curing systems. They function by accelerating the reaction between the epoxy resin and the curing agent, typically an anhydride or an amine. Among these tertiary amine catalysts, Bis[2-(N,N-Dimethylaminoethyl)] ether (BDMAEE) stands out due to its effectiveness and specific characteristics that influence the final properties of the cured adhesive. BDMAEE offers a balanced profile of reactivity, handling, and performance, making it a valuable component in many industrial adhesive formulations.

2. Chemical Structure and Properties of BDMAEE

BDMAEE is a tertiary amine ether with the following chemical structure:

(CH?)?NCH?CH?OCH?CH?N(CH?)?

Table 1: Physical and Chemical Properties of BDMAEE

Property	Value	Source
Molecular Formula	C??H??N?O	Supplier MSDS
Molecular Weight	188.31 g/mol	Supplier MSDS
CAS Registry Number	3033-62-3	Chemical Databases
Appearance	Colorless to light yellow liquid	Supplier MSDS
Density (at 20°C)	0.85 – 0.86 g/cm³	Supplier MSDS
Boiling Point	189-192 °C	Supplier MSDS
Flash Point	68-74 °C	Supplier MSDS
Viscosity (at 25°C)	1.8 – 2.2 mPa·s	Supplier MSDS
Water Solubility	Miscible	Supplier MSDS
Amine Value	~595 mg KOH/g	Supplier MSDS

Source: Typically derived from Material Safety Data Sheets (MSDS) provided by chemical suppliers and publicly available chemical databases.

3. Mechanism of Action in Epoxy Curing

BDMAEE acts as a catalyst in the epoxy curing process through a nucleophilic mechanism. It primarily promotes the homopolymerization of epoxy resin or accelerates the reaction between epoxy resin and hardeners, such as anhydrides or amines. The mechanism can be described in the following steps:

Initiation: The nitrogen atom in BDMAEE, possessing a lone pair of electrons, acts as a nucleophile and attacks the oxirane ring (epoxy group) of the epoxy resin. This ring-opening process creates a zwitterionic intermediate.
Propagation: The zwitterionic intermediate can then react with another epoxy molecule, propagating the chain. Alternatively, it can react with a protic species present in the system, such as water or an alcohol impurity, to generate a hydroxyl group and regenerate the tertiary amine catalyst.
Crosslinking (with Anhydrides): When used with anhydride curing agents, BDMAEE facilitates the reaction between the hydroxyl groups generated during epoxy ring opening and the anhydride functionality. This reaction forms ester linkages, contributing to the crosslinked network.
Crosslinking (with Amines): With amine curing agents, BDMAEE accelerates the reaction between the amine hydrogen and the epoxy group, forming a carbon-nitrogen bond and opening the epoxy ring.

The ether linkage in BDMAEE contributes to its solubility and compatibility within epoxy resin formulations. The two tertiary amine groups enhance its catalytic activity compared to mono-amine catalysts.

4. Advantages of Using BDMAEE in Epoxy Adhesive Systems

BDMAEE offers several advantages as a catalyst in epoxy resin curing systems for industrial adhesives:

Enhanced Cure Rate: BDMAEE significantly accelerates the curing process at room temperature or elevated temperatures, reducing cycle times and improving production efficiency.
Lower Curing Temperatures: The use of BDMAEE allows for curing at lower temperatures, which can be beneficial when dealing with heat-sensitive substrates or when energy consumption is a concern.
Improved Adhesive Strength: Properly formulated systems using BDMAEE can exhibit excellent adhesive strength, both in terms of shear strength and peel strength.
Good Chemical Resistance: Cured epoxy adhesives containing BDMAEE often demonstrate good resistance to various chemicals, including solvents, acids, and bases.
Low Volatility: Compared to some other tertiary amine catalysts, BDMAEE has a relatively low volatility, reducing the risk of air pollution and improving workplace safety.
Good Compatibility: The ether linkage in the molecule enhances its compatibility with a wide range of epoxy resins and other additives.
Controllable Reactivity: The catalytic activity of BDMAEE can be adjusted by varying its concentration in the formulation, allowing for fine-tuning of the curing process.

5. Limitations and Considerations

Despite its advantages, BDMAEE also has some limitations that need to be considered:

Potential for Yellowing: In some formulations, particularly those exposed to UV light or high temperatures, BDMAEE can contribute to yellowing of the cured adhesive. This can be mitigated through the use of UV stabilizers or alternative catalysts.
Moisture Sensitivity: BDMAEE is hygroscopic and can absorb moisture from the atmosphere. Moisture can react with the epoxy resin and negatively impact the curing process and the final properties of the adhesive. Proper storage and handling are essential.
Toxicity and Irritation: Like many tertiary amines, BDMAEE can be irritating to the skin, eyes, and respiratory system. Appropriate personal protective equipment (PPE) should be used when handling this chemical.
Influence on Glass Transition Temperature (Tg): The use of BDMAEE can affect the glass transition temperature (Tg) of the cured epoxy adhesive. The Tg is an important indicator of the thermal performance of the adhesive. Careful formulation is needed to achieve the desired Tg for specific applications.
Blooming: In some cases, BDMAEE can migrate to the surface of the cured adhesive, resulting in a phenomenon known as blooming. This can affect the appearance and performance of the adhesive.

6. Impact on Adhesive Properties

The incorporation of BDMAEE into epoxy resin curing systems significantly influences the properties of the resulting adhesive. The extent of this influence depends on factors such as the concentration of BDMAEE, the type of epoxy resin and hardener used, and the presence of other additives.

Table 2: Impact of BDMAEE on Adhesive Properties

Property	Impact	Considerations
Cure Speed	Increases cure speed significantly at room temperature and elevated temperatures.	Over-catalyzation can lead to rapid curing and reduced pot life. Optimize concentration based on the desired application.
Adhesive Strength	Generally improves adhesive strength (shear, peel) due to enhanced crosslinking.	Excessive BDMAEE can lead to brittleness and reduced impact resistance. Balance the concentration for optimal strength and toughness.
Chemical Resistance	Can improve chemical resistance, especially to solvents and acids.	The specific chemical resistance depends on the formulation and the type of epoxy resin and hardener used.
Thermal Properties (Tg)	Can influence the glass transition temperature (Tg) of the cured adhesive. May increase or decrease Tg depending on the formulation.	Target Tg should be considered based on the application’s temperature requirements.
Viscosity	May slightly reduce the viscosity of the epoxy resin mixture, improving handling and application.	The effect on viscosity is relatively small compared to the effect of other additives, such as diluents.
Color Stability	Can contribute to yellowing, especially upon exposure to UV light or high temperatures.	Use UV stabilizers or alternative catalysts to mitigate yellowing.
Pot Life	Decreases pot life due to accelerated curing.	Adjust the concentration of BDMAEE to achieve the desired pot life. Consider using latent catalysts for longer pot life applications.

7. Formulation Considerations

When formulating epoxy adhesives with BDMAEE, several factors should be considered to achieve the desired performance:

Epoxy Resin Selection: The type of epoxy resin used will significantly impact the properties of the cured adhesive. Common epoxy resins include bisphenol A epoxy resins, bisphenol F epoxy resins, and epoxy novolacs.
Hardener Selection: The choice of hardener is critical. Common hardeners include amines (e.g., aliphatic amines, cycloaliphatic amines, aromatic amines), anhydrides (e.g., phthalic anhydride, methyltetrahydrophthalic anhydride), and polyamides. The hardener type will influence the curing speed, mechanical properties, and chemical resistance of the adhesive.
BDMAEE Concentration: The concentration of BDMAEE should be optimized based on the desired cure speed, pot life, and final properties of the adhesive. Typical concentrations range from 0.1% to 5% by weight of the epoxy resin.
Other Additives: Other additives can be incorporated into the formulation to further enhance the properties of the adhesive. These additives may include:
- Fillers: To improve mechanical properties, reduce shrinkage, or lower cost (e.g., silica, calcium carbonate, talc).
- Diluents: To reduce viscosity and improve handling (e.g., reactive diluents, non-reactive diluents).
- Tougheners: To improve impact resistance and crack propagation resistance (e.g., liquid rubbers, core-shell rubbers).
- UV Stabilizers: To protect the adhesive from degradation due to UV light.
- Adhesion Promoters: To improve adhesion to specific substrates (e.g., silanes).
Mixing and Application: Proper mixing of the epoxy resin, hardener, BDMAEE, and other additives is essential for achieving uniform curing and optimal performance. The application method should also be considered.

Table 3: Formulation Guidelines for BDMAEE-Cured Epoxy Adhesives

Component	Typical Range (% by weight)	Function	Considerations
Epoxy Resin	40-80	Provides the base polymer matrix for the adhesive.	Choose epoxy resin based on desired properties (e.g., viscosity, Tg, chemical resistance).
Hardener	15-40	Reacts with the epoxy resin to form the crosslinked network.	Select hardener based on desired cure speed, mechanical properties, and chemical resistance.
BDMAEE	0.1-5	Catalyzes the curing reaction between the epoxy resin and the hardener.	Optimize concentration for desired cure speed and pot life.
Fillers	0-50	Improve mechanical properties, reduce shrinkage, lower cost.	Select filler based on desired properties and compatibility with the epoxy resin system.
Diluents	0-20	Reduce viscosity, improve handling.	Choose diluent based on compatibility and effect on final properties. Use reactive diluents when possible.
Tougheners	0-15	Improve impact resistance and crack propagation resistance.	Select toughener based on compatibility and desired level of toughness.
UV Stabilizers	0-2	Protect adhesive from degradation due to UV light.	Use when the adhesive will be exposed to UV light.
Adhesion Promoters	0-2	Improve adhesion to specific substrates.	Select adhesion promoter based on the substrate being bonded.

8. Applications in Industrial Adhesives

BDMAEE is utilized in various industrial adhesive applications, including:

Structural Adhesives: Used in aerospace, automotive, and construction industries for bonding structural components. Examples include bonding composite materials, metals, and plastics.
Electronic Adhesives: Used for encapsulating electronic components, bonding surface mount devices, and creating thermally conductive adhesives.
Coating Adhesives: Used in protective coatings for metal, concrete, and other surfaces, providing corrosion resistance and chemical resistance.
General Purpose Adhesives: Used for a wide range of bonding applications in various industries.

9. Safety and Handling

BDMAEE is a chemical that should be handled with care. The following safety precautions should be observed:

Personal Protective Equipment (PPE): Wear appropriate PPE, including gloves, safety glasses, and a respirator, when handling BDMAEE.
Ventilation: Use adequate ventilation to prevent inhalation of BDMAEE vapors.
Storage: Store BDMAEE in a cool, dry, and well-ventilated area. Keep away from heat, sparks, and open flames.
First Aid: In case of contact with skin or eyes, flush immediately with plenty of water. Seek medical attention if irritation persists. If inhaled, move to fresh air. If swallowed, do not induce vomiting. Seek medical attention immediately.

10. Future Trends

Research and development efforts are focused on:

Developing modified BDMAEE derivatives: To improve specific properties such as color stability, pot life, or reactivity.
Exploring the use of BDMAEE in combination with other catalysts: To achieve synergistic effects and optimize curing performance.
Investigating the use of BDMAEE in new epoxy resin systems: Such as bio-based epoxy resins and high-performance epoxy resins.
Developing encapsulated or latent BDMAEE catalysts: For improved pot life and controlled curing.

11. Conclusion

Bis[2-(N,N-Dimethylaminoethyl)] ether (BDMAEE) is a versatile and effective tertiary amine catalyst for epoxy resin curing systems used in industrial adhesives. Its ability to accelerate curing at lower temperatures, enhance adhesive strength, and provide good chemical resistance makes it a valuable component in many adhesive formulations. However, its potential for yellowing, moisture sensitivity, and toxicity should be carefully considered. By understanding the mechanism of action, advantages, limitations, and formulation considerations associated with BDMAEE, adhesive formulators can effectively utilize this catalyst to create high-performance adhesives for a wide range of industrial applications. Careful formulation and handling are essential to maximize the benefits of BDMAEE while minimizing potential risks.

12. References

Ellis, B. (1993). Chemistry and Technology of Epoxy Resins. Springer Science & Business Media.
Goodman, S. H. (1986). Handbook of Thermoset Plastics. Noyes Publications.
Lee, H., & Neville, K. (1967). Handbook of Epoxy Resins. McGraw-Hill.
May, C. A. (1988). Epoxy Resins: Chemistry and Technology. Marcel Dekker.
Skeist, I. (1958). Epoxy Resins. Reinhold Publishing Corporation.
Supplier Material Safety Data Sheets (MSDS) for BDMAEE.
Various patents and journal articles related to epoxy resin curing and tertiary amine catalysts.

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Bis[2-(N,N-Dimethylaminoethyl)] Ether (BDMAEE) in Low-Odor Epoxy Resin Formulations: A Comprehensive Overview

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