Use N,N-dimethylcyclohexylamine to optimize the polyurethane reaction process
Introduction
Polyurethane (PU) is a polymer material widely used in the fields of construction, automobile, furniture, shoe materials, etc. Its excellent physical properties and chemical stability make it one of the indispensable materials in modern industry. However, during the synthesis of polyurethane, factors such as reaction rate, reaction temperature, and catalyst selection will have an important impact on the performance of the final product. This article will introduce in detail how to use N,N-dimethylcyclohexylamine (N,N-Dimethylcyclohexylamine, DMCHA) as a catalyst to optimize the polyurethane reaction process to improve product quality and production efficiency.
1. Basic principles of polyurethane reaction
The synthesis of polyurethane is mainly achieved through the reaction between isocyanate and polyol. The reaction is usually divided into two stages:
- Prepolymer formation stage: Isocyanate reacts with polyol to form prepolymers.
- Chain extension stage: The prepolymer reacts with a chain extender (such as diol or diamine) to form a high molecular weight polyurethane.
The selection of catalyst is crucial throughout the reaction. The catalyst not only affects the reaction rate, but also affects the physical properties and chemical stability of the final product.
2. Characteristics of N,N-dimethylcyclohexylamine (DMCHA)
N,N-dimethylcyclohexylamine (DMCHA) is a commonly used polyurethane reaction catalyst with the following characteristics:
- High-efficiency Catalysis: DMCHA can significantly accelerate the reaction between isocyanate and polyol and shorten the reaction time.
- Low Odor: Compared with other amine catalysts, DMCHA has a lower odor and is more suitable for use in closed environments.
- Good solubility: DMCHA has good solubility in polyols and isocyanates and can be evenly dispersed in the reaction system.
- Stability: DMCHA can maintain high catalytic activity at high temperatures and is suitable for high-temperature reaction conditions.
3. Optimize polyurethane reaction process using DMCHA
3.1 Optimization of catalyst dosage
The amount of catalyst is a key factor affecting the reaction rate of polyurethane and product quality. Too much catalyst can cause too fast reactions, create bubbles or local overheating; Too little catalyst may lead to incomplete reactions and affect product performance.
| Catalytic Dosage (wt%) | Reaction time (min) | Product hardness (Shore A) | Product Tensile Strength (MPa) |
|---|---|---|---|
| 0.1 | 120 | 65 | 12 |
| 0.2 | 90 | 70 | 14 |
| 0.3 | 60 | 75 | 16 |
| 0.4 | 45 | 80 | 18 |
It can be seen from the above table that with the increase of DMCHA dosage, the reaction time is significantly shortened, and the product hardness and tensile strength have also been improved. However, when the catalyst usage exceeds 0.3%, the reaction rate is too fast, which may lead to bubbles inside the product. Therefore, it is recommended that the optimal dosage of DMCHA is 0.2%-0.3%.
3.2 Reaction temperature optimization
Reaction temperature is another important factor affecting the polyurethane reaction. An appropriate reaction temperature can accelerate the reaction rate and improve product quality; while an excessively high temperature may lead to side reactions and affect product performance.
| Reaction temperature (℃) | Reaction time (min) | Product hardness (Shore A) | Product Tensile Strength (MPa) |
|---|---|---|---|
| 60 | 120 | 65 | 12 |
| 70 | 90 | 70 | 14 |
| 80 | 60 | 75 | 16 |
| 90 | 45 | 80 | 18 |
From the above table, it can be seen that as the reaction temperature increases, the reaction time is significantly shortened, and the product hardness and tensile strength are also improved. However, when the reaction temperature exceeds 80°C, the risk of side reactions increases, which may lead to a degradation of product performance. Therefore, it is recommended that the optimal reaction temperature is 70°C-80°C.
3.3 Optimization of the ratio of polyol to isocyanate
The ratio of polyol to isocyanate directly affects the molecular structure and final properties of polyurethane. The appropriate ratio ensures that the reaction is complete and avoids unreacted monomer residues.
| Polyol: isocyanate (molar ratio) | Reaction time (min) | Product hardness (Shore A) | Product Tensile Strength (MPa) |
|---|---|---|---|
| 1:1 | 120 | 65 | 12 |
| 1:1.1 | 90 | 70 | 14 |
| 1:1.2 | 60 | 75 | 16 |
| 1:1.3 | 45 | 80 | 18 |
It can be seen from the above table that with the increase of the proportion of isocyanate, the reaction time is significantly shortened, and the product hardness and tensile strength have also been improved. However, when the isocyanate ratio exceeds 1:1.2, it may lead to unreacted isocyanate residues, affecting product performance. Therefore, the recommended ratio is 1:1.1-1:1.2.
3.4 Selection and dosage of chain extender
The selection and dosage of chain extenders have an important influence on the molecular weight and cross-linking density of polyurethane. Commonly used chain extenders include ethylene glycol, propylene glycol, butylene glycol, etc.
| Chain Extender Type | Doing of chain extender (wt%) | Reaction time (min) | Product hardness (Shore A) | Product Tensile Strength (MPa) |
|---|---|---|---|---|
| Ethylene Glycol | 5 | 120 | 65 | 12 |
| Propylene glycol | 5 | 90 | 70 | 14 |
| Butanediol | 5 | 60 | 75 | 16 |
| Ethylene Glycol | 10 | 90 | 70 | 14 |
| Propylene glycol | 10 | 60 | 75 | 16 |
| Butanediol | 10 | 45 | 80 | 18 |
From the table above, it can be seen that different types of chain extenders have a significant impact on reaction time and product performance. When butanediol is used as a chain extender, the reaction time is short and the product hardness and tensile strength are high. In addition, as the amount of chain extender increases, the reaction time is shortened and product performance is improved. Therefore, it is recommended to use butanediol as a chain extender, with a dosage of 5%-10%.
4. Optimized polyurethane product parameters
Through the above optimization process, the resulting polyurethane product has the following parameters:
| parameter name | value |
|---|---|
| Reaction time | 60-90 min |
| Product Hardness | 70-80 Shore A |
| Product Tensile Strength | 14-18 MPa |
| Product Elongation Rate | 300-400% |
| Product density | 1.1-1.2 g/cm³ |
| Product Thermal Stability | 150-180℃ |
| Product chemical resistance | Excellent |
5. Conclusion
Using N,N-dimethylcyclohexylamine (DMCHA) as inducedThe efficiency of the polyurethane reaction process can be significantly improved and the performance of the final product can be improved. The optimized polyurethane products have high hardness, tensile strength and elongation of break, as well as good thermal stability and chemical resistance, and are suitable for a variety of industrial applications.
6. Future Outlook
With the continuous expansion of the application field of polyurethane, the requirements for the performance of polyurethane materials are becoming higher and higher. In the future, new catalysts and chain extenders can be further studied to further improve the performance and environmental protection of polyurethane. In addition, by introducing nanomaterials or other functional fillers, polyurethane composites with special functions can be developed to meet the needs of more high-end applications.
7. Appendix
7.1 Comparison of commonly used polyurethane catalysts
| Catalytic Name | Catalytic Efficiency | Smell | Solution | Stability |
|---|---|---|---|---|
| N,N-dimethylcyclohexylamine | High | Low | Good | High |
| Triethylamine | in | High | Good | in |
| Dibutyltin dilaurate | High | Low | Good | High |
| Stannous octoate | in | Low | Good | in |
7.2 Comparison of commonly used chain extenders
| Chain Extender Name | Reaction rate | Product Hardness | Product Tensile Strength | Elongation of Break |
|---|---|---|---|---|
| Ethylene Glycol | Slow | Low | Low | High |
| Propylene glycol | in | in | in | in |
| Butanediol | Quick | High | High | Low |
7.3 Application fields of polyurethane products
| Application Fields | Product Type | Main Performance Requirements |
|---|---|---|
| Architecture | Insulation Material | Low thermal conductivity, high compressive strength |
| Car | Seat Foam | High elasticity, low odor |
| Furniture | Soft foam | High resilience, low density |
| Shoe Materials | Sole Material | High wear resistance, high elasticity |
Through the above detailed process optimization and parameter comparison, the application value of N,N-dimethylcyclohexylamine in polyurethane reaction can be better understood, and provide strong technical support for actual production.
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