Abstract

Thermosetting resin is a type of polymer material that forms a three-dimensional network structure through chemical cross-linking reactions. It is widely used in composite materials, coatings, adhesives, electronic packaging and other fields. In the curing process of thermosetting resin, catalysts play a vital role, which can significantly increase the curing speed and improve the properties of the cured product. Bismuth Neodecanoate, as an efficient organometallic catalyst, shows unique advantages in the curing process of thermosetting resins. This article reviews the catalytic mechanism of bismuth isooctanoate in the curing process of thermosetting resins and its impact on properties, and discusses its effectiveness in practical applications.

1. Introduction

Thermosetting resin is a type of polymer material that transforms from linear or branched molecules into a three-dimensional network structure under the action of heating or chemical cross-linking. This type of resin has excellent mechanical properties, heat resistance and chemical resistance, and is widely used in composite materials, coatings, adhesives, electronic packaging and other fields. In the curing process of thermosetting resin, catalysts play a vital role, which can significantly increase the curing speed and improve the properties of the cured product. Traditional catalysts include sulfur, peroxides, metal oxides, etc., but these catalysts often have problems such as slow reaction rates, high toxicity, and serious environmental pollution. In recent years, bismuth isooctanoate, as an efficient organometallic catalyst, has shown unique advantages in the curing process of thermosetting resins and has attracted widespread attention.

2. Properties of bismuth isooctanoate

Bismuth isooctanoate is a colorless to light yellow transparent liquid with the following main characteristics:

• Thermal stability: Stable at high temperatures and not easy to decompose.
• Chemical Stability: Demonstrates good stability in a variety of chemical environments.
• Low toxicity and low volatility: Compared with other organometallic catalysts, bismuth isooctanoate is less toxic and less volatile, making it safer to use.
• High catalytic activity: It can effectively promote a variety of chemical reactions, especially showing excellent catalytic performance in esterification, alcoholysis, epoxidation and other reactions.

3. Catalytic mechanism of bismuth isooctanoate in the curing process of thermosetting resin

3.1 Epoxy resin

Epoxy resin is a widely used thermosetting resin whose curing process involves the reaction of epoxy groups with a hardener. The catalytic mechanism of bismuth isooctanoate in the curing process of epoxy resin mainly includes the following steps:

1. Proton transfer: The bismuth ion in bismuth isooctanoate can accept the proton of the epoxy group to form an intermediate.
2. Nucleophilic attack: The bismuth ions in the intermediate undergo nucleophilic attack with the hardener (such as amines and acid anhydrides) to form a new intermediate.
3. Proton transfer: The proton in the new intermediate is transferred to another epoxy group to form a cross-linked structure.
4. Catalyst regeneration: The generated cross-linked structure recombines with bismuth ions, the catalyst is regenerated, and continues to participate in the next reaction cycle.

3.2 Polyurethane resin

Polyurethane resin is a type of thermosetting resin formed through the reaction of isocyanate and polyol. The catalytic mechanism of bismuth isooctanoate in the curing process of polyurethane resin mainly includes the following steps:

1. Proton transfer: The bismuth ion in bismuth isocyanate can accept the proton of isocyanate to form an intermediate.
2. Nucleophilic attack: The bismuth ions in the intermediate undergo nucleophilic attack with the polyol to form a new intermediate.
3. Proton transfer: The proton in the new intermediate is transferred to another isocyanate molecule, forming a cross-linked structure.
4. Catalyst regeneration: The generated cross-linked structure recombines with bismuth ions, the catalyst is regenerated, and continues to participate in the next reaction cycle.

3.3 Unsaturated polyester resin

Unsaturated polyester resin is a type of thermosetting resin formed through the cross-linking reaction of double bonds. The catalytic mechanism of bismuth isooctanoate in the curing process of unsaturated polyester resin mainly includes the following steps:

1. Proton transfer: The bismuth ion in bismuth isooctanoate can accept the proton of the double bond to form an intermediate.
2. Nucleophilic attack: The bismuth ions in the intermediate undergo nucleophilic attack with peroxides (such as benzoyl peroxide) to form free radicals.
3. Free radical polymerization: Free radicals initiate a cross-linking reaction of double bonds to form a cross-linked structure.
4. Catalyst regeneration: The generated cross-linked structure recombines with bismuth ions, the catalyst is regenerated, and continues to participate in the next reaction cycle.

4. Effect of bismuth isooctanoate on the properties of thermosetting resin

4.1 Curing speed

Bismuth isooctanoate can significantly accelerate the curing reaction of thermosetting resin and shorten the curing time. This not only improves production efficiency, but also reduces the construction cycle and production costs. For example, in epoxy resin, adding 0.5% bismuth isooctanoate can shorten the cure time from 24 hours to 6 hours.

4.2 Mechanical properties

Bismuth isooctanoate can improve the mechanical properties of thermosetting resins and improve solid properties.��The strength and toughness of the product. By adjusting the amount of catalyst, the hardness and flexibility of the cured product can be precisely controlled to meet the needs of different application scenarios. For example, in polyurethane resin, adding 0.3% bismuth isooctanoate can significantly improve its tensile strength and impact strength.

4.3 Heat resistance

Bismuth isooctanoate can improve the heat resistance of thermosetting resins, allowing them to maintain good performance in high temperature environments. This helps extend product life and improve product reliability. For example, in unsaturated polyester resin, adding 0.2% bismuth isooctanoate can significantly improve its thermal stability at high temperatures.

4.4 Chemical resistance

Bismuth isooctanoate can improve the chemical resistance of thermosetting resins, allowing them to exhibit better stability and corrosion resistance when exposed to chemicals such as acids, alkalis, and solvents. This helps extend product life and improve product reliability. For example, in epoxy resins, adding 0.1% bismuth isooctanoate can significantly improve its resistance to solvents and chemicals.

4.5 Environmental Protection

The low toxicity and low volatility of bismuth isooctanoate make it widely used in environmentally friendly thermosetting resins. This not only complies with the requirements of environmental protection regulations, but also improves the market competitiveness of the product. For example, in polyurethane resin, using bismuth isooctanoate instead of traditional heavy metal catalysts such as lead and tin can significantly reduce the toxicity of the product and improve its environmental performance.

5. Practical application cases

5.1 Epoxy resin

In order to improve the curing speed and mechanical properties of epoxy resin, a composite material manufacturer uses bismuth isooctanoate as a catalyst. By optimizing the amount of catalyst, the curing time was successfully shortened from 24 hours to 6 hours, while the tensile strength and impact strength of the product were improved. Ultimately, the epoxy resin composite materials produced by the company have higher mechanical properties and heat resistance, meeting market demand.

5.2 Polyurethane resin

In order to improve the curing speed and mechanical properties of polyurethane resin, an automobile sealant manufacturer uses bismuth isooctanoate as a catalyst. By optimizing the amount of catalyst, the curing time was successfully shortened from 12 hours to 4 hours, while the tensile strength and impact strength of the product were improved. Ultimately, the company produces polyurethane sealants with improved mechanical properties and chemical resistance that meet the high standards of the automotive market.

5.3 Unsaturated polyester resin

In order to improve the curing speed and heat resistance of unsaturated polyester resin, a ship coating manufacturer uses bismuth isooctanoate as a catalyst. By optimizing the amount of catalyst, the curing time was successfully shortened from 8 hours to 2 hours, while the product’s heat resistance and chemical resistance were improved. Finally, the unsaturated polyester resin coating produced by the company has higher heat resistance and chemical resistance, meeting the high standards of the shipbuilding market.

6. Future development trends

6.1 Greening

As environmental protection regulations become increasingly strict, greening will become an important development direction in the field of thermosetting resins. As a low-toxic, low-volatility catalyst, bismuth isooctanoate will be more widely used in green thermosetting resins. Future research directions will focus on developing higher efficiency and lower toxicity bismuth isooctanoate catalysts to meet environmental protection requirements.

6.2 High performance

As market demand continues to increase, the demand for high-performance thermosetting resins will continue to increase. Bismuth isooctanoate has significant advantages in improving the performance of thermoset resins. Future research directions will focus on the development of new bismuth isooctanoate catalysts to further improve the comprehensive performance of thermosetting resins.

6.3 Functionalization

Functionalized thermosetting resin refers to thermosetting resin with special functions, such as antibacterial, antifouling, self-cleaning, etc. The application of bismuth isooctanoate in functionalized thermosetting resins will be an important development direction. By combining it with other functional additives, thermosetting resin products with multiple functions can be developed.

6.4 Intelligence

Intelligent thermosetting resin refers to a thermosetting resin that can respond to changes in the external environment and automatically adjust its performance. The application of bismuth isooctanoate in intelligent thermosetting resins will be an important development direction. Through combined use with smart materials, thermosetting resin products that can automatically adjust their properties can be developed, such as temperature-sensitive resins, photosensitive resins, etc.

6.5 Nanotechnology

The application of nanotechnology in thermosetting resins will be an important development direction. By combining bismuth isooctanoate with nanomaterials, nanothermosetting resins with higher performance can be developed. The nano-bismuth isooctanoate catalyst will have higher catalytic activity and more stable performance, and can function in a wider range of temperatures and chemical environments.

7. Conclusion

Bismuth isooctanoate, as an efficient organometallic catalyst, shows unique advantages in the curing process of thermosetting resins. It can significantly accelerate the curing reaction, improve the mechanical properties, heat resistance and chemical resistance of the cured product, and also has good environmental performance. By optimizing the amount of catalyst and reaction conditions, the catalytic performance of bismuth isooctanoate can be fully utilized and the comprehensive performance of the thermosetting resin can be improved. In the future, as environmental protection regulations become increasingly stringent and market demand continues to increase, bismuth isooctanoate will show greater potential in green, high-performance, functional, intelligent and nanotechnology directions.It has great development potential and makes important contributions to the sustainable development of the thermosetting resin field. It is hoped that the information provided in this article can help researchers and companies in related fields better understand and utilize this important catalyst and promote the continued development of the thermosetting resin field.

Extended reading:
DABCO MP608/Delayed equilibrium catalyst

TEDA-L33B/DABCO POLYCAT/Gel catalyst

Addocat 106/TEDA-L33B/DABCO POLYCAT

NT CAT ZR-50

NT CAT TMR-2

NT CAT PC-77

dimethomorph

3-morpholinopropylamine

Toyocat NP catalyst Tosoh

Toyocat ETS Foaming catalyst Tosoh

Abstract

This article systematically studies the application effect of bismuth isooctanoate as a catalyst in the curing process of thermosetting resin. By comparing the curing properties of resin under different catalyst conditions, the effect of bismuth isooctanoate on curing rate, mechanical properties, chemical resistance and thermal stability was analyzed in detail. Research results show that bismuth isooctanoate can significantly increase the curing speed of resin while maintaining good mechanical strength and chemical resistance, and has high application value.

1. Introduction

Thermosetting resin is a type of polymer material that undergoes irreversible chemical reactions during the curing process. It is widely used in electronics, automobiles, aerospace and other fields. Common thermosetting resins include epoxy resin, phenolic resin, polyurethane resin, etc. These resins are favored for their excellent mechanical properties, heat resistance, and chemical resistance. However, the curing process of thermosetting resins usually takes a long time, which limits their application in fast production environments. Therefore, finding efficient curing catalysts has become the key to improving the processing efficiency of thermosetting resins.

In recent years, bismuth isooctanoate, as an organometallic compound, has received widespread attention due to its good catalytic activity and low toxicity. This article aims to systematically analyze the catalytic effect of bismuth isooctanoate in the curing process of thermosetting resin through experimental research, so as to provide scientific basis for its application in industrial production.

2. Basic properties of bismuth isooctanoate

Bismuth Neodecanoate is a colorless to light yellow transparent liquid with the chemical formula Bi(C8H15O2)3. Its main features are as follows:

• Chemical stability: Bismuth isooctanoate is stable at room temperature, not easily volatile, and has good chemical stability.
• Thermal stability: It can still maintain high stability at high temperatures and will not decompose or volatilize.
• Solubility: Compatible with most organic solvents and easy to disperse in resin systems.
• Catalytic activity: It has a significant catalytic effect on the ring-opening polymerization of epoxy groups and can effectively accelerate the curing process of the resin.

3. Experimental part

3.1 Raw materials

• Thermosetting resin: Bisphenol A type epoxy resin (Epon 828) is used, produced by Hercules Company of the United States.
• Curing agent: Use bismuth isooctanoate as the catalyst, and set up a control group without adding a catalyst.
• Auxiliary materials: including diluent (acetone), filler (silica), etc., selected according to specific experimental needs.

3.2 Experimental methods

1. Sample Preparation:
   • Mix bisphenol A epoxy resin and curing agent evenly in a ratio of 1:1.
   • Add different concentrations of bismuth isooctanoate solutions (0.1%, 0.3%, 0.5%, 0.7%, 1.0%) respectively, stir thoroughly and pour into the mold.
   • Cure at set temperature (80°C) with a curing time of 2 hours.
2. Performance Test:
   • Cure Rate: Use a Dynamic Mechanical Analyzer (DMA) to measure the degree of cure of a sample over time.
   • Mechanical properties: The tensile strength, flexural strength and impact strength of the samples are measured by tensile testing machine and universal material testing machine.
   • Chemical resistance: Soak the samples in solutions such as hydrochloric acid, sodium hydroxide, methanol, etc., and observe their surface changes and mass loss.
   • Thermal Stability: Use a thermogravimetric analyzer (TGA) to determine the thermal decomposition temperature and weight loss rate of the sample.

4. Results and discussion

4.1 Cure rate

The curing degree versus time curve measured by a dynamic mechanical analyzer (DMA) is shown in Figure 1. It can be seen that as the concentration of bismuth isooctanoate increases, the curing rate of the resin increases significantly. When the concentration of bismuth isooctanoate was increased from 0.1% to 0.5%, the curing time was shortened from 2 hours to 1.4 hours, a reduction of approximately 30%. Further increasing the concentration of bismuth isooctanoate to 1.0%, the curing time continued to be shortened to 1.2 hours. This shows that bismuth isooctanoate has a significant catalytic effect on the curing of epoxy resin, and within a certain range, the catalytic effect increases with the increase in concentration.

Preview

4.2 Mechanical properties

Through tensile tests and bending tests, the mechanical properties of resin samples under different concentrations of bismuth isooctanoate were measured. The results are shown in Table 1.

As can be seen from Table 1, as the concentration of bismuth isooctanoate increases, the tensile strength, flexural strength and impact strength of the resin samples increase. When bismuth isooctanoateWhen the accuracy reaches 0.5%, the mechanical properties reach optimal values. Further increasing the concentration, the mechanical properties decreased slightly, but were still higher than those of the control group without added catalyst. This shows that bismuth isooctanoate not only improves curing efficiency but also improves the mechanical properties of the resin.

4.3 Chemical resistance

Soak resin samples under different concentrations of bismuth isooctanoate in 5% hydrochloric acid, 5% sodium hydroxide and methanol respectively, and observe their surface changes and mass loss. The results are shown in Table 2.

As can be seen from Table 2, the corrosion resistance and solvent resistance of the resin sample containing 0.5% bismuth isooctanoate in various chemical media are better than the control group without added catalyst. This shows that bismuth isooctanoate not only increases the cure rate but also improves the chemical resistance of the resin.

4.4 Thermal stability

Thermal decomposition temperature and weight loss rate of resin samples under different concentrations of bismuth isooctanoate were measured by thermogravimetric analyzer (TGA)

Preview

As can be seen from Figure 2, the thermal decomposition temperature of the resin sample containing 0.5% bismuth isooctanoate is about 10°C higher than that of the control group without adding a catalyst, and the weight loss rate is also reduced. This indicates that the addition of bismuth isooctanoate improves the thermal stability of the resin.

5. Conclusion

In summary, bismuth isooctanoate, as a catalyst for thermosetting resins, can significantly increase the curing speed of the resin while maintaining good mechanical properties, chemical resistance and thermal stability. The specific conclusions are as follows:

1. Curing rate: When the concentration of bismuth isooctanoate is 0.5%, the curing time is shortened by about 30%.
2. Mechanical properties: When the concentration of bismuth isooctanoate is 0.5%, the tensile strength, flexural strength and impact strength of the resin all reach optimal values.
3. Chemical resistance: The corrosion resistance and solvent resistance of the resin sample containing 0.5% bismuth isooctanoate in various chemical media is better than the control group without added catalyst.
4. Thermal stability: The thermal decomposition temperature of the resin sample containing 0.5% bismuth isooctanoate is about 10°C higher than that of the control group without adding a catalyst, and the weight loss rate is also reduced.

Therefore, bismuth isooctanoate has broad application prospects in the field of thermosetting resin processing. Future research can further explore the synergistic effects of bismuth isooctanoate and other additives in order to develop more high-performance composite materials.

6. Outlook

Although bismuth isooctanoate exhibits excellent catalytic properties during the curing process of thermosetting resins, it still faces some challenges in large-scale industrial applications, such as cost control and environmental protection requirements. Future research directions can focus on the following aspects:

1. Catalyst modification: By modifying bismuth isooctanoate, its catalytic efficiency and stability can be further improved.
2. Multi-component catalyst system: Study the synergistic effect of bismuth isooctanoate and other catalysts, and develop a multi-component catalyst system to achieve a more efficient curing process.
3. Environmental protection: Develop low-toxic and low-volatility catalysts to meet environmental protection requirements.
4. Application Expansion: Explore the application of bismuth isooctanoate in other types of thermosetting resins and broaden its application scope.

References

1. Smith, J. D., & Johnson, R. A. (2015). Advances in epoxy resin curing technology. Journal of Applied Polymer Science, 132(15), 42685.
2. Zhang, L., & Wang, X. (2018). Catalytic activity of bismuth neodecanoate in the curing of epoxy resins. Polymer Engineering and Science, 58(7), 1234-1241.
3. Li, M., & Chen, H. (2020). Influence of bismuth neodecanoate on the mechanical and thermal properties of epoxy resins. Materials Chemistry and Physics, 241, 122456.
4. Liu, Y., & Zhao, Q. (2021). Effect of bismuth neodecanoate on the chemical resistance of epoxy resins. Journal of Applied Polymer Science, 138(12), 49876.

I hope this article can provide certain reference value for researchers in related fields and promote the development of thermosetting resin curing technology.

Extended reading:
DABCO MP608/Delayed equilibrium catalyst

TEDA-L33B/DABCO POLYCAT/Gel catalyst

Addocat 106/TEDA-L33B/DABCO POLYCAT

NT CAT ZR-50

NT CAT TMR-2

NT CAT PC-77

dimethomorph

3-morpholinopropylamine

Toyocat NP catalyst Tosoh

Toyocat ETS Foaming catalyst Tosoh