Introduction to Polyurethane Elastomer
Polyurethane elastomer, a polymer synthetic material between rubber and plastic, is known as the “fifth plastic”. Thanks to its high strength, elasticity, wear resistance, shock absorption, and chemical stability, it’s widely used in various industries.
Classification by Raw Material Form
1. Thermoplastic Elastomers (TPU)
- Characteristics: TPU offers good wear and tear resistance. It also has high elasticity, resilience, and mechanical strength. Additionally, it resists oil and solvents well and can be processed through injection molding, extrusion, or blow molding.
- Properties: Its hardness ranges from Shore 60A to 80D. It has high tensile strength (over 50MPa), large elongation at break (300% – 700%), good low – temperature flexibility, and weather and anti – aging resistance.
2. Thermosetting Polyurethane Elastomers (CPU)
- – Characteristics: CPU shows excellent wear resistance, maintaining surface quality under long – term use. It has high mechanical strength, resists oil and solvents, absorbs shock, and has good dimensional and bonding properties.
- – Properties: Tensile strength is 20 – 50 MPa, elongation at break is 300% – 800%, and hardness ranges from Shore A 10 – Shore D 80. It works in – 40°C to 120°C, has good resilience, aging resistance, and dynamic damping.
Classification by Polyol Type
- **Polyester Polyols**
– **Characteristics**: They feature high strength and hardness, as well as good oil and solvent resistance.
– **Properties**: Polyester polyols have high cohesion and adhesion. However, due to ester bonds, their hydrolysis stability is relatively poor.
- **Polyether Polyols**
– **Characteristics**: These offer good low – temperature flexibility, excellent hydrolysis and mold resistance.
– **Properties**: They have low viscosity, making processing easy. Moreover, they have good air permeability and hygroscopicity.
Classification by Isocyanate Raw Material
- **MDI**
– MDI has relatively high hardness and strength. It also offers good wear and tear resistance. Although it’s a bit expensive, it has lower toxicity than TDI and good molding properties.
- **TDI**
– TDI is relatively inexpensive, with obvious cost advantages. It’s easy to process, offering good elasticity and softness. However, it may be volatile and toxic.
- **IPDI**
– IPDI has good weather, hydrolysis, and yellowing resistance. Additionally, its low viscosity makes operation easy.
- **PPDI**
– PPDI shows outstanding heat resistance. It also has high hardness and strength but is on the pricey side.
- **NDI**
– NDI has extremely high strength, excellent dynamic performance, and good heat and oil resistance. Nevertheless, it usually comes at a high price.
Polyurethane Elastomer AB Compound
Material A is typically the polyol component, which may include polyether or polyester polyols, along with additives. Material B is usually the isocyanate component, like MDI or TDI. When using, they’re mixed in a certain proportion and cured chemically to form the elastomer. Note that product performance is affected by factors like polyol type, formulation ratios, and processing techniques.
How to Choose Polyurethane Elastomer Materials
- **Mechanical Performance Requirements**
– If high strength and wear resistance are needed, NDI or PPDI – based elastomers may be suitable. For general requirements, MDI or TDI – based ones usually suffice. For good low – temperature performance and elasticity, IPDI is a better choice.
- **Temperature Resistance Performance**
– In high – temperature environments, PPDI or NDI – based elastomers are preferred. For normal temperatures, MDI, TDI, or IPDI can work.
- **Chemical Corrosion Resistance**
– When in contact with strong chemicals, choose MDI or PPDI – based materials with good corrosion resistance.
- **Weather Resistance**
– For long – term outdoor use with color stability needs, IPDI – based elastomers are more appropriate.
- **Cost Limitations**
– When on a budget, MDI and TDI – based elastomers are more cost – effective.
- **Dynamic Performance**
– For dynamic load applications, NDI – based elastomers are ideal due to their excellent performance.
- **Processing Technology and Production Efficiency**
– Different raw materials have different reaction activities and processing conditions. Some are suitable for large – scale production, while others meet special requirements.
- **Environmental Protection Requirements**
– Pay attention to environmental indicators like VOC emissions and toxicity, and select environmentally friendly materials.
In conclusion, by comprehensively considering these factors, communicating with us based on specific scenarios and requirements, we can assist in choosing the right polyurethane elastomer materials and conducting small – sample tests.
