What is TPR Material: Uses and Comparison with TPE Explained

TPR (Thermo-Plastic-Rubber) material, also known as thermoplastic rubber, represents a unique category of materials that combine rubber elasticity without the need for vulcanization. This makes TPR materials directly processable into various forms, such as through injection molding, extrusion, and blow molding. TPR is primarily based on thermoplastic styrene-butadiene rubber (SBS or SEBS), blended with resins like polypropylene (PP) or polystyrene (PS), fillers, plasticizers, and other functional additives to create a modified, soft, thermoplastic elastomer.

In this article, we will explore the characteristics, applications, and comparisons between TPR and Thermoplastic Elastomer (TPE).

What is TPR Material?

TPR is primarily composed of Styrene Butadiene Styrene (SBS), a block copolymer synthesized through living anionic polymerization. This process creates a polymer structure with hard, crystalline regions that provide thermoplastic properties and soft, amorphous regions that deliver elastomeric qualities. TPR retains its flexibility and durability under heat. It is ideal for applications requiring high grip and complex geometries that necessitate thermoplastic processing.

Key Properties of TPR Rubber

Thermoplastic rubber (TPR) exhibits several important properties that make it a preferred choice in various applications, the following tables summarize the chemical and physical properties of TPR:

Property	Description
Chemical Resistance	Resists various chemicals, oils, and solvents
UV Resistance	Maintains performance when exposed to UV light
Water Resistance	Exhibits low water absorption
Hardness	Typically ranges from 30 to 90 Shore A
Tensile Strength	Generally between 5 to 25 MPa
Elongation at Break	Can exceed 300%
Temperature Range	Effective from -40°C to +90°C
Density	Approximately 0.9 to 1.2 g/cm³
Compression Set	Low compression set, ensuring resilience
Abrasion Resistance	High resistance to wear and tear
Flexural Modulus	Ranges from 30 to 300 MPa
Specific Gravity	Generally around 0.9 to 1.1
Melt Flow Rate	Varies based on formulation, typically low
Thermal Conductivity	Moderate thermal conductivity
Electrical Insulation	Good dielectric properties

Chemical Resistance of TPR

Here are key aspects of its chemical resistance:

Chemical Type	Resistance Level	Comments
Oils	Good	Resistant to mineral oils and lubricants
Greases	Good	Performs well with most industrial greases
Acids	Moderate	Generally resistant to weak acids
Alkalis	Moderate	Resistance varies with concentration
Solvents	Fair	Limited resistance to strong solvents
Hydrocarbons	Good	Effective against various hydrocarbons
Alcohols	Fair	Resistance can vary; consult specific grades
Esters	Poor	Generally not recommended for prolonged contact
Amines	Poor	Limited compatibility; may cause degradation
Salt Solutions	Good	Stable in saline environments
Detergents	Good	Typically resistant to household detergents
Antifreeze	Good	Compatible with common antifreeze solutions
Cleaning Agents	Good	Generally resistant to many cleaning agents
Plating Solutions	Fair	Resistance may vary based on specific formulation
Phenols	Poor	Not recommended due to potential degradation

How TPR Rubber is Manufactured?

TPR (Thermoplastic Rubber) is produced as plastic pellets that can be utilized in various melt-processing manufacturing techniques. Each method has unique advantages and applications, allowing for the creation of diverse products.

Rubber Injection Molding

In this method, molten TPR is injected into a precisely shaped mold under high pressure. This technique is ideal for creating parts with intricate designs and features. The process allows for precise control over the dimensions and surface finish of the final product. Additionally, TPR can be molded over a rigid substrate in a process known as overmolding, which is commonly used to create soft grips on tools and handles. Overmolding combines the durability of hard materials with the comfort of TPR, making it popular in consumer products.

Extrusion

In extrusion, molten TPR is pushed through a die to create products with a continuous cross-section, such as tubes, seals, and profiles. The extrusion process is highly efficient, allowing for high-volume production and uniformity in dimensions. Extruded TPR can be cut to specific lengths or rolled into sheets, making it versatile for various applications. This method is particularly useful for creating components that require consistent shapes and sizes.

Blow Molding

Blow molding involves using air pressure to force molten TPR against the inner walls of a mold. This technique is typically employed to create hollow objects, such as bottles and containers, with thin walls. The process allows for efficient production of lightweight components with complex shapes, making it suitable for packaging applications. Blow molding can produce items quickly and economically, offering significant material savings compared to other methods.

Calendering

Calendering is a process where molten TPR is passed through a series of rollers to create flat sheets. This method is often used to manufacture flexible sheets, which can include fabric cores for added strength. The resulting sheets are used in applications such as conveyor belts, flooring, and protective covers. Calendering allows for precise control over thickness and texture, making it suitable for products that require specific surface finishes.

What is TPR Material Used For?

TPR materials find extensive applications across multiple industries due to their versatility and rubber-like properties. These include:

• Daily Products: Items like handles, grips, and seals.
• Adult Products: Due to its soft touch and flexibility.
• Hardware Tools: Components requiring durability and flexibility.
• Luggage Wheels: For shock absorption and smooth rolling.
• Sporting Goods: Equipment handles and grips.
• Toy Products: Especially in the form of soft toys and squeeze toys.
• Automotive Parts: Components like seals and gaskets.
• Medical Products: Devices needing flexibility and biocompatibility.
• Wire and Cable: Insulation and jacketing.
• Electronics and Electrical: Components requiring flexibility and electrical insulation.
• Footwear: Soles and other parts for comfort and flexibility.

Comparison with TPE

TPE (Thermoplastic Elastomer) is another type of thermoplastic elastic material that shares similarities with TPR but also has distinct differences.

TPR vs. TPE: Applications and Uses

TPR has been widely used for applications that require flexibility, durability, and slip resistance. Some typical applications are listed below:

• Shoe soles
• Dog toys
• Tire treads
• Gaskets
• Sporting goods grips
• Electrical insulation components

TPE is also utilized in various applications, particularly where elasticity and performance are critical. Some typical applications are listed below:

• Automotive seals and gaskets
• Soft-touch surfaces for consumer electronics
• Medical devices that require sterilization
• Household products such as kitchenware and toothbrushes
• Industrial hoses and tubing
• Conveyor belts

Both TPR and TPE offer unique advantages, making them suitable for a range of uses across different industries. Understanding their specific applications helps manufacturers choose the right material for their needs.

TPR vs. TPE: Physical Properties

Table 1 below lists the mechanical, thermal, and electrical properties of TPR and TPE:

Table 1: TPR vs. TPE Physical Properties

Properties	Thermoplastic Rubber (TPR)	Thermoplastic Elastomer (TPE)
Tensile Strength (MPa)	2.5 – 25	5 – 30
Melting Temperature Range (°C)	140–185	200 – 250
Impact Strength (Izod Notched) (J/cm)	3 – 6	4 – 8
Hardness (Shore A & D)	30 – 90 A	40 – 100 A
Modulus of Elasticity (GPa)	0.1 – 1.0	0.5 – 2.0
Elongation at Break (%)	300 – 600	300 – 700
Tear Resistance (N/mm)	10 – 30	15 – 40
Dielectric Strength (kV/mm)	20 – 30	20 – 50

Both TPR and TPE offer a range of physical properties suitable for various applications. TPR tends to excel in applications requiring softness and flexibility, while TPE provides higher temperature resistance and mechanical performance. Always consult a material supplier for specific property data when selecting materials for particular uses.

TPR vs. TPE: Recyclability and Sustainability

Both TPR and TPE are derived from petroleum-based sources, raising concerns about their sustainability and environmental impact.

TPR is a thermoplastic, which means it can theoretically be recycled. However, actual recycling rates for TPR are low, largely due to the challenges of processing lower-volume materials economically. Like many plastics, TPR often ends up in landfills or contributes to environmental pollution, making its recyclability less impactful.

TPE also has the potential for recycling, as it shares thermoplastic characteristics. TPE can sometimes be processed back into new products, but similar to TPR, its recycling is not widespread. The overall recycling rates for TPE remain low, and many products still find their way to landfills.

Both materials face significant challenges regarding recyclability and sustainability, highlighting the importance of developing better recycling infrastructures and exploring more sustainable alternatives in the industry.

TPR vs. TPE: Cost

Thermoplastic Rubber (TPR) is generally more expensive than many common thermoplastic elastomers (TPE). The cost of TPR typically ranges from $1,470 to $2,250 per metric ton, reflecting its specialized properties and manufacturing processes. In comparison, TPE can vary widely in price, often falling between $1,200 and $2,000 per metric ton, depending on the specific formulation and properties required.

The cost difference is influenced by factors such as production volume, material properties, and market demand. When selecting between TPR and TPE, manufacturers must consider both performance requirements and budget constraints to ensure they choose the most cost-effective option for their applications.

TPR as an Injection Molding Material

TPR (Thermoplastic Rubber) is an ideal material for injection molding due to its flexibility, durability, and ease of processing. It allows for complex shapes and offers a comfortable rubber-like feel, making it suitable for products like grips, seals, and toys. TPR’s resistance to wear and chemicals ensures longevity in applications such as automotive and medical devices.

At BOYI, we offer specialized injection molding services to deliver high-quality TPR components for your projects.