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The manufacturing method of polyurethane resin is a high-performance and multifunctional polymer material widely used in the field of chemical raw materials. This article will introduce the manufacturing methods of polyurethane resin, including raw material selection, preparation process, reaction mechanism, and influencing factors

1、 Raw material selection 

1 Polyols are one of the main raw materials for polyurethane resins, commonly used including polyols, polyester polyols, and polyether polyols. When selecting polyols, factors such as molecular weight, functionality, and hydroxyl value need to be considered to meet the performance requirements of different products

2. Diisocyanate 

Diisocyanate is another main raw material for polyurethane resins, commonly used include diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), etc. When choosing diisocyanates, factors such as their activity, toxicity, and stability need to be considered

3. Chain extenders 

Chain extenders are substances used to regulate the molecular weight of polyurethane, commonly used include small molecule diols, diamines, etc. When selecting a chain extender, factors such as its compatibility with polyols, diisocyanates, and chain extender efficiency need to be considered

2、 The preparation process of polyurethane resin mainly includes prepolymer method and one-step method

1. Prepolymer method 

Prepolymer method is to react polyols and diisocyanates under certain conditions to form prepolymers, and then add chain extenders for chain extension reaction to generate polyurethane resin. The polyurethane resin obtained by this method has a high molecular weight and stable performance, but the process is relatively complex

2. One step method 

One step method is to add polyols, diisocyanates, and chain extenders together into a reactor and react under certain conditions to produce polyurethane resin. The polyurethane resin obtained by this method has a low molecular weight, but the process is simple and the production efficiency is high

3、 The reaction mechanism of polyurethane resin mainly includes two steps: prepolymer generation and chain extension reaction

1. Prepolymer generation 

Polyols and diisocyanates react under certain conditions to form prepolymers. During the reaction process, factors such as temperature and pH value need to be controlled to ensure the smooth progress of the reaction

2. Chain extension reaction 

After adding a chain extender to the prepolymer, the chain extender reacts with the isocyanate groups in the prepolymer to form polyurethane resin. Chain extension reaction requires controlling factors such as reaction time and temperature to ensure the molecular weight and performance of the product

4、 The factors that affect the performance of polyurethane resin mainly include the following aspects: 

1 Different types and ratios of raw materials can affect the performance of polyurethane resin, so it is necessary to choose appropriate raw materials according to specific application requirements

2. Reaction temperature and time 

The reaction temperature and time will affect the degree of prepolymer and chain extension reaction, thereby affecting the performance and molecular weight of polyurethane resin

3. pH value 

pH value can affect the reaction activity of diisocyanates during the formation process of prepolymers, so it is necessary to control the pH value to ensure the smooth progress of the reaction

4. Types and dosages of chain extenders 

Different types and dosages of chain extenders can affect the molecular weight and properties of polyurethane resins, so it is necessary to choose appropriate chain extenders and dosages according to specific application requirements

In summary, the manufacturing method of polyurethane resin needs to consider the comprehensive effect of multiple factors to ensure the performance and quality of the product. Meanwhile, with the continuous progress of technology and the increasing demand for applications, the manufacturing methods of polyurethane resin are also constantly improving and optimizing.