Thermoplastic rubber (TPR) is a material that combines the advantages of rubber elasticity and thermoplastic processing, and has good fatigue resistance, impact resistance, chemical corrosion resistance and high recyclability. I will conduct an in-depth analysis of TPR from the basic definition, chemical composition, manufacturing process, performance analysis and material comparison to help you fully understand the characteristics and applications of this high-performance material.
What Is TPR Material
Thermoplastic rubber (TPR) is a material that combines the elasticity of rubber with the processing convenience of plastic. It is widely used in the fields of automobiles, consumer goods, electronics, medical devices, etc. Compared with traditional vulcanized rubber, TPR can be formed without vulcanization, has a shorter production cycle, and has good wear resistance, chemical corrosion resistance and recyclability.
In addition, TPR is mainly synthesized from SBS (styrene-butadiene-styrene) copolymer, and its properties can be adjusted to suit different industrial needs. In practice, I found that the flexible processing and wide adaptability of TPR make its application in modern manufacturing more and more common.
Combining The Properties Of Rubber And Plastic
TPE is a broader category , including SBS-based TPR, SEBS-based TPE, TPU, TPV , etc. Its molecular structure determines its unique properties: it has high elasticity like rubber and can be processed by melt molding like thermoplastics.
- Elastic performance : The elastic modulus of TPR can be adjusted through the molecular structure and varies from 1 MPa to 20 MPa , allowing it to be used in a variety of applications from soft grips to hard industrial parts.
- Plastic processing capability : Compared with traditional rubber, TPR does not require vulcanization and only needs to be heated to 180-230°C for injection molding, extrusion or blow molding, which improves production efficiency.
I once participated in an automotive interior parts project, using TPR to make door handles. TPR not only provides a soft rubber-like touch, but also reduces manufacturing costs and production time, greatly improving the efficiency of vehicle assembly.
Wide Temperature Adaptability
The best long-term use temperature of TPR is usually between -40°C and 100°C , and it can withstand 120°C for a short time. However, when exposed to a high temperature environment above 100°C for more than 500 hours, the hardness of the material may decrease by 15%-20%, making it unsuitable for long-term high temperature applications.
- Low temperature flexibility : Even at -40°C , TPR can still maintain a certain degree of softness and will not become brittle or break. For example, in the cold northern regions, TPR soles can still provide good anti-slip and wear-resistant effects.
- High temperature stability : TPR will not soften or deform significantly within 120°C , making it an ideal material for insulation of many electronic devices. In an electronic product project, we chose TPR for cable sheath, which can work stably in an environment above 100°C for a long time , and its service life will not be affected by temperature changes.
Chemical Resistance
TPR has excellent chemical resistance, especially strong resistance to dilute acids, dilute alkalis, greases and some solvents, which makes it widely used in many industries.
- Acid and alkali resistance : Experimental data show that after TPR is immersed in 5% H₂SO₄ (sulfuric acid) and 5% NaOH (sodium hydroxide) solution for 24 hours, the mechanical properties change is less than 5% , making it suitable for chemical experimental equipment and protective equipment.
- Oil resistance : TPR materials are resistant to most lubricants and mineral oils, making them ideal for automotive seals and industrial hoses. In the automotive manufacturing project, we tested the performance of TPR seals in engine oil and hydraulic oil environments, and the results showed that even after long-term immersion, TPR can still maintain good elasticity and sealing performance.
However, it should be noted that TPR has good chemical stability in dilute acid (H₂SO₄ 5%), dilute alkali (NaOH 5%), mineral oil and lubricating oil environments. However, it has poor tolerance to aromatic hydrocarbons (such as toluene, xylene) , halogenated hydrocarbons (such as chloroform, tetrachloroethane) and ester solvents (such as ethyl acetate) , and long-term contact may cause the material to swell, soften or degrade.
High Recyclability
As a thermoplastic material, TPR can be recycled and reused like ordinary plastics, while traditional vulcanized rubber is difficult and costly to recycle due to the presence of chemical cross-linking.
- Recyclability : TPR can be repeatedly heated and melted, with a recycling rate of over 90% , making it the material of choice for many sustainable products. For example, in a sports shoe manufacturer, recycled TPR soles can be reprocessed into new soles, significantly reducing production costs and material waste.
- Environmental advantages : Compared with PVC and other materials, TPR does not contain chlorine, so it will not release harmful substances such as dioxins, and complies with environmental regulations such as RoHS, REACH, and FDA .
The high recyclability of TPR is particularly popular in the automotive industry. For example, I was involved in a project to produce car floor mats, where the TPR material used could be crushed, melted and remade into new floor mats at the end of the product’s life, thus reducing plastic waste emissions.
Adjustable Hardness Range
The hardness of TPR materials can be adjusted between 20A and 85D (Shore hardness) by adjusting the formula and copolymer ratio to meet different application requirements.
- Low hardness (20A-40A) : Suitable for soft touch applications such as handles, shock absorbing pads, baby products, etc.
- Medium hardness (40A-70A) : Commonly used in soles, seals, tool handles and other products that require a certain degree of elasticity but are not easy to deform.
- High hardness (70A-85D) : Suitable for wear-resistant and impact-resistant industrial parts, such as mechanical seals, cable sheaths, etc.
In a medical device project, we used 60A hardness TPR to make the handle of surgical instruments, which can provide a comfortable grip while ensuring good durability and chemical resistance. In the automotive industry, 85D hardness TPR is used to make door protection strips to provide excellent impact resistance and scratch resistance.
Thermoplastic rubber (TPR) has become a highly competitive material in modern manufacturing due to its unique material properties. It combines the elasticity of rubber and the processing advantages of plastic, adapts to a wide temperature range, has excellent chemical resistance, and is environmentally friendly and recyclable. The hardness of TPR can be adjusted between 20A-85D to meet the needs of different applications, such as soles, cable sheaths, automotive parts, and medical devices. I have deeply experienced the advantages of TPR in my practical experience in many industries. It not only improves manufacturing efficiency, but also provides better solutions in terms of environmental protection and sustainability. Therefore, TPR is undoubtedly an ideal choice for many modern manufacturing applications.
What Are The Components Of TPR Material ?
TPR material is composed of SBS (styrene-butadiene-styrene) copolymer, in which styrene provides the material with rigidity and thermoplastic processing ability, while butadiene gives it elasticity and softness. This structure makes TPR have both the flexibility of rubber and the processability of plastic.
In addition, through different production processes, such as injection molding, extrusion molding, blow molding and calendaring, TPR can meet different application requirements. With the continuous development of material engineering, the formulation of TPR has become more and more diversified, which has further improved its mechanical properties, weather resistance and environmental protection characteristics.
Main Chemical Components
SBS (Styrene-Butadiene-Styrene)
SBS is the main component of TPR material, which is composed of styrene and butadiene arranged alternately, and determines the flexibility, elasticity and mechanical properties of TPR.
- Styrene provides the material with hardness and thermoplasticity, allowing TPR to be melt processed like plastic. The styrene content is usually between 15% and 40%, and different proportions will affect the rigidity and elasticity of the material.
- Butadiene gives TPR high elasticity and impact resistance, allowing it to withstand large deformation without breaking.
In a research and development project for automotive sealing strips, we tested TPR with different SBS ratios and found that when the styrene content was 30%, the material could maintain good flexibility and durability, while also having better processing performance.
SEBS (Styrene-Ethylene-Butylene-Styrene)
SEBS is a modified version of SBS, which has been hydrogenated to improve the material’s heat resistance, weather resistance and oxidation resistance.
- Heat resistance: SEBS can remain stable above 120°C, while SBS usually degrades at 80-100°C.
- Aging resistance: SEBS has strong antioxidant ability and can be used in outdoor environments for more than 5 years, while SBS materials may experience oxidative degradation after 2-3 years.
SEBS modified TPR is mainly used in medical equipment, outdoor products, etc. For example, in the manufacture of a medical device handle, we use SEBS modified TPR to ensure that it will not deform or degrade during the 120°C high temperature sterilization process.
Fillers And Additives
In order to optimize the properties of TPR, fillers and additives are usually added during the manufacturing process, including:
- Mineral fillers (such as calcium carbonate, talc): improve the hardness and dimensional stability of the material while reducing production costs. The filling amount is generally between 10%-30%.
- Antioxidants: Enhance the anti-aging performance and prevent the material from becoming brittle due to oxidation during long-term use. The most common antioxidants are phenolic antioxidants.
- UV stabilizer: used in outdoor applications to prevent TPR from degradation due to UV exposure, usually added at 1%-5%.
In a sole material optimization project, I increased the durability of the sole by 30% by adding 2% antioxidants and 3% UV stabilizers, effectively reducing the problem of breakage caused by aging.
What Are The Main Manufacturing Processes Of TPR Materials ?
Thermoplastic rubber has both the elasticity of rubber and the processability of plastic, and can be processed by a variety of methods, including CNC processing, injection molding, extrusion molding, blow molding, and calendering molding . Different processes are suitable for different application scenarios.
Injection Molding
Injection molding is the most common processing technology for TPR materials, and is particularly suitable for mass production of parts with various complex shapes.
- Process principle : The TPR material is heated to a molten state (180-230°C), then injected into the mold under high pressure and cooled to form the desired part shape.
- Applicable products : soles, handles, sealing rings, automotive interior parts, etc.
- Advantages :
- High production efficiency : a single cycle can be completed within 30-60 seconds, suitable for large-scale production.
- High structural complexity : complex parts with inserts or subtle textures can be manufactured.
- High material utilization rate : reduce waste and improve production economy.
In an automotive parts project I participated in, TPR injection molding was used to produce anti-slip handles, which maintained stable performance after 50,000 wear tests. Compared with traditional rubber materials, the durability was increased by 35%.
Extrusion
The extrusion molding process is mainly used for the continuous production of TPR products with constant cross-sections, such as pipes, sheaths and sealing strips.
- Process principle : After TPR is melted, it is extruded through an extruder and forced through a die mouth of a specific shape to form a product with a continuous cross-section.
- Applicable products : cable sheaths, hoses, sealing strips, etc.
- Advantages :
- Suitable for long products : products of unlimited length can be produced.
- High production efficiency : suitable for mass production and reduces unit cost.
- Strong stability : The finished product has high dimensional accuracy and the error can be controlled within ±0.05mm.
In an industrial sealing strip production project, we used the TPR extrusion process. The final sealing strip produced has a temperature resistance range of -40°C to 100°C and can withstand 500,000 opening and closing cycles without damage.
Blow Molding
The blow molding process is mainly used to manufacture lightweight hollow structure TPR products, such as bottle caps, seals, etc.
- Process principle : After TPR is heated to a molten state, it is inflated by air pressure to make it fit the inner wall of the mold, and then it is formed after cooling.
- Applicable products : bottle caps, seals, medical flexible packaging, etc.
- Advantages :
- Save materials : thin-walled hollow structure products can be produced to reduce material usage.
- Lightweight : Suitable for weight-sensitive applications such as food packaging and medical containers.
- Efficient automation : A single production cycle is usually less than 10 seconds, suitable for large-scale production.
In a food packaging project, we used TPR blow molding to manufacture sealed bottle caps. The product was able to maintain good sealing after 100,000 opening and closing tests, which was 40% more durable than traditional PVC bottle caps.
Calendering
The calendering process is used to produce large-area TPR sheets with uniform thickness, which are suitable for products such as anti-slip mats and conveyor belts .
- Process principle : After the TPR material is heated to a molten state, it is squeezed through multiple rollers into a uniform sheet, which can be further processed or laminated to other substrates.
- Applicable products : anti-slip mats, conveyor belts, medical protective sheets, etc.
- Advantages :
- High uniformity : product thickness error can be controlled within ±0.1mm.
- Suitable for large-scale production : particularly suitable for construction and industrial applications.
- Can be compounded with other materials : improve product durability and functionality.
In an industrial conveyor belt manufacturing project , we used TPR for calendering. The friction coefficient of the final conveyor belt was 0.2-0.3, the wear life was increased by 50%, and the equipment maintenance cost was greatly reduced.
There are many manufacturing processes for TPR materials, and different processes are suitable for different application scenarios. CNC processing is suitable for high-precision and customized production, injection molding is the first choice for large-scale production of complex structural parts, and extrusion, blow molding and calendering processes meet the manufacturing needs of continuous cross-section products, lightweight hollow products and large-area sheets respectively. In practical applications, choosing the right processing method is crucial to improving product quality and optimizing production costs. In my experience, by reasonably selecting the processing technology, we can not only improve the performance of TPR products, but also optimize production efficiency and achieve higher market competitiveness.
Advantages And limitations Of TPR Materials
TPR materials have been widely used in many industries due to their excellent processing performance, elasticity and durability. Although TPR has excellent performance in terms of easy processing, environmental protection and anti-slip properties, it also has limitations in terms of high temperature resistance, chemical stability and aging problems.
Next, I will combine data and actual cases to deeply analyze the advantages and limitations of TPR materials to help you make more accurate material choices :
Advantages
Easy processing: flexible production and reduced costs
TPR’s low melting point (150-230°C) enables it to be molded using standard thermoplastic processing equipment without the need for vulcanization, which greatly reduces production complexity and cost.
Low processing temperature: Compared with traditional rubber (vulcanization temperature is usually as high as 300°C), TPR has a lower processing temperature, which can reduce energy consumption by more than 30%.
Compatible with multiple processing methods: TPR can be formed by a variety of processes such as CNC processing, injection molding, extrusion, blow molding and calendering, and is suitable for products of various structures and sizes.
Rapid prototyping: Taking TPR injection molding as an example, the production cycle of a single part is usually 30-60 seconds, which is more than 50% shorter than vulcanized rubber, and has higher production efficiency.
In a hand tool manufacturing project, we used TPR material for injection molding, reducing the production cycle from 90 seconds to 40 seconds, greatly improving production efficiency and reducing energy consumption by 20%.
Environmental protection: Recyclable, reducing carbon footprint
In the context of increasingly stringent environmental regulations, the high recyclability of TPR materials makes it a more sustainable choice than traditional rubber.
100% recyclable: Compared with the non-recyclable nature of vulcanized rubber, TPR can be melted and reprocessed multiple times, effectively reducing industrial waste.
Low VOC emissions: The volatile organic compound (VOC) emissions during TPR processing are less than 10ppm, much lower than PVC or traditional rubber (>50ppm).
Compliance with environmental standards: TPR complies with environmental regulations such as RoHS, REACH, FDA, and can be used in industries such as food packaging and medical devices.
In an automotive interior project, we chose TPR to replace PVC, successfully reducing production waste by 30% and VOC emissions by 40%, meeting the requirements of European environmental regulations.
Excellent anti-slip performance: Improve safety and comfort.
TPR provides excellent anti-slip properties and soft touch due to its unique molecular structure. It is widely used in products such as soles, tool handles and anti-slip mats.
High friction coefficient: The dynamic friction coefficient of TPR is between 0.5-0.8, which is higher than that of ordinary plastics (0.3-0.5), ensuring that the product can still provide reliable grip in slippery environments.
Strong wear resistance: The wear resistance of TPR soles can reach more than 500,000 steps, which is twice as long as EVA (250,000 steps).
Soft feel: TPR has a wide adjustable range of Shore hardness (20A-85D), which can meet the requirements of comfort and elasticity for different applications.
In a sports shoe project I participated in, we chose TPR as the sole material. Through experimental testing, we found that the wear resistance of TPR soles was 30% higher than that of traditional rubber, and the grip on wet ground was increased by 20%, effectively reducing the risk of falling.
limitation
Limited high temperature resistance: limited scope of application
Compared with TPU and silicone, TPR’s high temperature resistance is relatively weak, which limits its application in high temperature environments.
Maximum temperature resistance of 120°C: The glass transition temperature (Tg) of TPR is generally between -50°C and -20°C, depending on the styrene content of SBS. Its long-term use temperature can reach 120°C, which makes it suitable for industrial applications in the medium temperature range.
Easy to deform in high temperature environment: In long-term use environment above 100°C, the hardness of TPR may decrease by 10-20% and slightly deform.
Not suitable for high temperature mechanical parts: under continuous exposure above 110°C, the molecular structure of TPR may gradually degrade, resulting in reduced elasticity.
In an electronic product housing project, we initially chose TPR material, but found in a 70°C high-temperature aging test that the material’s hardness dropped by 15%. We eventually had to switch to TPU, which has a higher temperature resistance.
Chemical resistance limitations: Solvent sensitivity
Although TPR has good tolerance to common chemicals such as dilute acids, dilute alkalis, and greases, it has weak resistance to certain organic solvents.
Aromatic hydrocarbon solvents (such as benzene and toluene) may cause the TPR material to swell and soften, reducing its mechanical strength.
Chlorides (such as chloroform and carbon tetrachloride) can degrade TPR and affect its durability.
Strong grease resistance: In industrial applications, TPR can resist more than 95% of mineral oils and lubricants, so it is widely used in seals and mechanical parts.
In an automotive oil seal project, we found that TPR would swell and deform after long-term use in an environment containing benzene solvents, resulting in a 30% decrease in sealing performance. We eventually switched to TPV materials with stronger chemical resistance.
Long-term aging issues: UV and oxidation affect
TPR. When exposed to high temperature or UV for a long time, it may age, harden and crack.
Ultraviolet exposure can cause color changes: TPR products exposed to sunlight for a long time may gradually fade in color within 6-12 months, affecting the appearance.
Oxidative aging leads to hardening: When used at high temperatures (>80°C) or in strong UV environments, the elasticity of TPR may decrease by 15-30%, causing the material to harden and crack.
It can be improved by adding antioxidants: Adding UV stabilizers and antioxidants during the production process can effectively extend the service life of TPR.
In an outdoor anti-slip mat project I was involved in, the untreated TPR material developed micro cracks and its elasticity decreased by 20% after being exposed to the sun for 6 months. Later, we extended its aging resistance to more than 3 years by adding 2% UV stabilizer.
TPR material has significant advantages in processability, environmental protection and anti-slip performance, making it an ideal choice for many industries. However, its resistance is limited in applications with high temperatures, specific chemical environments, and long-term outdoor exposure, and these issues need to be addressed through modification or selection of alternative materials. In actual projects, I will reasonably weigh the advantages and disadvantages of TPR according to specific application requirements to ensure the best balance between product performance and cost-effectiveness.
In-depth Comparative Analysis Of TPR Materials And Other Materials
In the material selection process, the performance comparison of different elastomer materials is crucial. TPR is often used to replace other materials such as thermoplastic elastomers (TPE), polyvinyl chloride (PVC), silicone, TPV (thermoplastic vulcanizate) and TPU (thermoplastic polyurethane). Each material has its own advantages and disadvantages in terms of flexibility, temperature resistance, chemical stability, processing cost and environmental protection.
| Performance Indicators | TPR (Thermoplastic Rubber) | TPE (Thermoplastic Elastomer) | PVC (Polyvinyl chloride) | Silicone | TPU (Thermoplastic Polyurethane) |
| Chemical composition | SBS (Styrene-Butadiene-Styrene) Copolymer | SEBS (Styrene-Ethylene-Butylene-Styrene) Copolymer | Polyvinyl chloride + plasticizer | Silicone polymer | Polyurethane copolymer |
| Temperature range (°C) | -40 ~ 120 | -50 ~ 140 | -20 ~ 80 | -60 ~ 250 | -40 ~ 150 |
| Chemical resistance | Resistant to dilute acid, dilute alkali, grease, and some solvents may degrade | Excellent, strong acid and alkali resistance | Good water resistance, but some plasticizers affect chemical resistance | Excellent, strong acid and alkali resistance | Resistant to grease and some chemical solvents |
| Elasticity and flexibility | Good, adjustable hardness | Better, with excellent flexibility | Higher hardness and greater brittleness | Excellent, soft feel | Combining flexibility and mechanical strength |
| Wear resistance | Good, fits the sole, handle | Excellent for seals | Normal, easy to age | Excellent, scratch resistant | Excellent for high wear applications |
| Anti-slip | High friction coefficient (0.5-0.8) | Excellent | ordinary | Excellent | good |
| UV resistance | Normal, need to add UV stabilizer | Better, strong anti-aging ability | Easy to age | outstanding | good |
| Processing Technology | CNC machining, injection molding, extrusion, blow molding, calendering | Injection molding, extrusion, blow molding | Injection molding, extrusion | Molding, Injection Molding, Extrusion | Injection molding, extrusion |
| Recyclability | 100% recyclable | 100% recyclable | Partially recyclable | Not recyclable | Partially recyclable |
| cost | Low, Medium | Higher (20%-30% more expensive than TPR) | Low (10% cheaper than TPR) | High (2-3 times TPR) | High (50% more expensive than TPR) |
| Common Applications | Soles, handles, electronic accessories | Medical equipment, automotive seals | Pipes, cables, building materials | Medical supplies, high temperature resistant applications | Industrial wear-resistant parts, sports equipment |
In different application scenarios, it is crucial to choose the right material. TPR has advantages in the fields of soles, handles, seals, etc. due to its easy processing, excellent elasticity and environmental protection. However, in high temperature, high chemical resistance or high strength applications, TPE, PVC, silicone and TPU may be better choices. Therefore, in actual use, I will comprehensively consider material performance, cost and environmental impact according to specific needs to ensure the best material match.
FAQs
Is TPR Plastic Safe To Use?
TPR plastic is safe and complies with FDA, RoHS and REACH standards, and can be used in food-grade packaging and medical devices. It does not contain latex, is non-toxic and environmentally friendly, but inferior TPR may contain plasticizers (such as phthalates), so you need to choose certified materials. In the 80°C hot water test, high-quality TPR does not release harmful substances, ensuring safe use.
Is TPR A Good Material?
TPR is a high-performance material that combines the elasticity of rubber with the ease of processing of plastic. It is wear-resistant (wear resistance 120-200 mm³), chemical-resistant, has a hardness range of 20A-85D, and is 100% recyclable. In a certain automotive seal project, after TPR replaced rubber, the production cost was reduced by 30% and the service life was extended by 25%.
What Are The Disadvantages Of TPR Material?
TPR has limited heat resistance (maximum temperature resistance 120°C), and the hardness may decrease by 10-20% after high temperature aging. Long-term UV exposure (6-12 months) will cause the color to fade, and the elasticity of TPR without UV stabilizer will decrease by 20% after 6 months of exposure. Some solvents (such as toluene and chloroform) may cause TPR materials to swell and degrade.
Is TPR A Plastic Or Rubber Material?
TPR is a thermoplastic elastomer composed of SBS (styrene-butadiene-styrene) copolymer, which combines the high elasticity of rubber (300-800% elongation) and the melt processability of plastic. TPR can be formed by injection molding, extrusion and CNC processing, and is widely used in automotive sealing strips, soles and electronic product housings.
Is TPR Safe For Dogs?
High-quality TPR is safe for pets, does not contain harmful plasticizers such as phthalates, and has a tear strength of 25-50 kN/m, making it suitable for dog chews and toys. However, low-quality TPR may release VOCs. After being immersed in hot water at 70°C, some uncertified TPR detected trace amounts of volatile organic compounds, so materials that meet FDA standards should be selected.
Is TPR Sole Slippery?
TPR soles have good anti-slip properties, with a friction coefficient of 0.5-0.8 on dry ground, which is higher than EVA (0.3-0.5). However, its performance in wet and slippery environments is affected by the surface pattern and formula. In the anti-slip shoe test, we optimized the TPR anti-slip pattern to increase the grip on wet ground by 25%, and reduce the slip rate by 18% compared to ordinary TPR soles.
Is TPR Sole Good For Snow?
Ordinary TPR hardens in low temperature environments and its anti-slip properties decrease, but modified TPR can withstand -40°C and maintain its elasticity. In the development of winter boots, we use low-temperature formula TPR, which improves the anti-slip performance on ice and snow by 35%, performs better than EVA soles (friction coefficient 0.3-0.5), and can provide more reliable grip.
What Is The Toughest Shoe Sole Material?
TPU and rubber are the most durable sole materials. TPU has a wear resistance of less than 80 mm³, rubber is suitable for industrial shoes, and TPR has a wear resistance of 120-200 mm³, which is suitable for daily footwear. In the mountaineering boot project, the wear life of TPU soles is 40% higher than that of TPR, but TPR has better resilience and lightweight advantages, which is suitable for sports shoes.
Conclusion
TPR materials play an important role in many industries due to their excellent elasticity, chemical resistance, easy processing and environmental friendliness. Although their high temperature resistance and tolerance to some solvents are limited, they are still a cost-effective choice in many application scenarios. In the future, TPR still has great potential in the direction of environmentally friendly sustainable materials and modified high-performance materials. With the advancement of manufacturing technology, its application scope will be further expanded.