描述
Santoprene 121-70M350 is a soft, black, UV-resistant thermoplastic vulcanizate (TPV) from Celanese developed for automotive interior gap fillers, sealing components and appearance-critical molded parts.
The grade is positioned differently from general-purpose Santoprene TPV. Celanese’s automotive grade slate places Santoprene 121-70M350 in the interior application group and identifies its principal advantage as improved scratch and mar resistance.
This is particularly important for interior parts that remain visible to vehicle occupants. A material may have adequate flexibility and mechanical strength but still be unsuitable if repeated touching, rubbing, assembly contact or normal use produces visible scuffing or surface damage.
Santoprene 121-70M350 is designed to address this combination of elastomeric flexibility, appearance quality and scratch resistance.
Celanese also describes the grade as suitable for gap filler applications requiring scratch resistance and good appearance.
Typical examples include instrument-panel-to-windshield gap fillers, interior sealing interfaces, flexible trim interfaces and other soft black molded components where appearance is part of the engineering requirement.
The grade has a Shore A hardness of approximately 70, providing a useful balance between softness and support.
At this hardness level, the material remains flexible enough to function as an elastomeric seal or filler while being firm enough to maintain part geometry and a controlled surface appearance.
Current grade data lists approximately 480% elongation at break, 6.2 MPa stress at break, 2.6 MPa stress at 100% elongation and a shear modulus of approximately 7.47 MPa.
This property profile makes Santoprene 121-70M350 well suited to molded parts that must deform during assembly or service without behaving like a rigid plastic.
The material also has a density of approximately 0.930 g/cm³, which is lower than many conventional rubber and engineering-plastic systems and can contribute to lightweight automotive component design.
Processing is another major advantage.
Celanese specifically describes Santoprene 121-70M350 as being designed for fast, easy injection molding, especially for complex part geometries.
The grade is shear dependent, meaning its apparent viscosity decreases as shear rate increases. This behavior can improve mold filling through appropriate gate design, screw speed and injection velocity.
Celanese also states that the grade is designed to be injected at lower molding temperatures or lower injection pressures.
For complex interior parts with thin flow paths, fine details or appearance-sensitive surfaces, this can be useful for reducing injection pressure demand and improving the process window.
The current grade-specific optimum melt temperature is approximately 215°C.
Celanese recommends drying Santoprene TPV for approximately 3 hours at 80°C and states that the general Santoprene TPV processing window is approximately 175–230°C.
The grade is polyolefin based and recyclable within the manufacturing stream, providing the production advantages commonly associated with Santoprene TPV compared with fully crosslinked thermoset rubber.
For more grades, visit our TPV Thermoplastic Vulcanizates Product Category →.
For Celanese’s current Santoprene portfolio and grade positioning, see the Official Celanese Santoprene & Geolast Product Finder →.
Key Features of Santoprene 121-70M350
| Feature | Engineering Benefit |
|---|---|
| Shore A 70 | Balanced firmness and elastomeric flexibility |
| Improved Scratch & Mar Resistance | Better appearance retention in visible automotive interior parts |
| UV Resistant | Supports applications exposed to sunlight through vehicle glazing or outdoor conditions |
| Superior Surface Appearance | Suitable for visible gap fillers and trim interfaces |
| High-Flow Injection Molding | Supports complex part geometries |
| Lower-Temperature Molding Capability | Can reduce thermal load during processing |
| Lower-Pressure Injection Capability | Helps fill complex tools with lower injection-pressure demand |
| 480% Elongation at Break | Allows substantial deformation without brittle failure |
| 6.2 MPa Stress at Break | Provides useful mechanical strength for flexible molded parts |
| Shear-Dependent Flow | Flow improves as shear rate increases |
| Polyolefin-Based TPV | Low density and conventional thermoplastic processing |
| Manufacturing-Stream Recyclability | Controlled process scrap may be recyclable within the manufacturing stream |
| Automotive OEM References | Current data lists Mercedes-Benz and Volkswagen Group specifications |
The central selling point of Santoprene 121-70M350 is not simply its 70A hardness. It is the combination of appearance quality, scratch/mar resistance and injection-molding performance.
Typical Applications for Santoprene 121-70M350
Santoprene 121-70M350 is primarily targeted at automotive interior and sealing applications.
| Application Area | Typical Use |
|---|---|
| Instrument Panel Gap Fillers | Flexible fillers between the instrument panel and windshield area |
| Interior Gap Fillers | Soft black parts that close visible gaps between trim components |
| Interior Seals | Flexible interfaces between adjacent interior parts |
| Appearance-Critical Molded Parts | Components requiring good molded surface quality |
| Scratch-Resistant Soft Trim | Flexible parts subject to touching or rubbing |
| Automotive Sealing Components | Seals requiring 70A hardness and clean appearance |
| Complex Injection-Molded Parts | Components with difficult flow paths or fine geometry |
| UV-Exposed Interior Parts | Interior components exposed to sunlight through vehicle glass |
| Flexible Trim Interfaces | Soft interfaces between rigid interior components |
| Black Decorative Elastomeric Parts | Functional black parts where surface appearance matters |
Celanese’s automotive grade slate specifically associates the grade with the interior category and lists IP-to-windshield gap fillers among typical Santoprene interior applications.
For this reason, Santoprene 121-70M350 should be considered first when the design challenge is not only flexibility, but also visible surface durability.
Typical Properties of Santoprene 121-70M350
Physical Properties
| Property | Typical Value | Test Method |
|---|---|---|
| Density | 930 kg/m³ / 0.930 g/cm³ | ISO 1183 |
| Specific Gravity | Approx. 0.928–0.930 | ASTM D792 / ISO 1183 |
| Shore A Hardness, 15 s | 70 | ISO 48-4 / ISO 868 |
| Color | Black | Manufacturer information |
| Product Form | Pellets | Manufacturer information |
| UV Resistance | Yes | Manufacturer positioning |
Mechanical Properties
| Property | Typical Value | Test Method |
|---|---|---|
| Stress at 100% Elongation | 2.6 MPa | ISO 527-1/-2 or ISO 37 |
| Stress at Break | 6.2 MPa | ISO 527-1/-2 or ISO 37 |
| Elongation at Break | 480% | ISO 527-1/-2 or ISO 37 |
| Shear Modulus | 7.47 MPa | ISO 6721 |
| Shore A Hardness | 70 | ISO 48-4 / ISO 868 |
| Compression Set, 70°C / 24 h | 40% | ISO 815 |
The approximately 480% elongation shows that Santoprene 121-70M350 remains highly deformable even though it is positioned as a 70A grade.
The 40% compression-set value should be interpreted in the context of its intended application. This grade is optimized heavily around surface appearance, scratch/mar resistance and flow, rather than being selected purely for the lowest possible compression set.
Processing Properties
| Property | Typical Value |
|---|---|
| Recommended Drying | Yes |
| Drying Temperature | 80°C |
| Drying Time | 3 hours |
| Optimum Melt Temperature | 215°C |
| General Santoprene Processing Window | 175–230°C |
| Primary Process | Injection Molding |
| Multi-Injection Molding | Suitable |
Scratch and Mar Resistance of Santoprene 121-70M350
A major distinction of Santoprene 121-70M350 is its positioning for improved scratch and mar resistance.
Scratch and mar damage can be especially noticeable on black elastomeric automotive interior parts because light-colored surface marks can create strong visual contrast.
A gap filler or seal may still function mechanically after being rubbed or scuffed, but visible damage can reduce perceived quality.
For this reason, interior materials are often selected using a combination of hardness, surface finish, scratch visibility, mar resistance, gloss level, texture reproduction, color consistency, flexibility and UV stability.
Santoprene 121-70M350 is designed specifically for this appearance-driven engineering environment.
Celanese’s automotive grade slate identifies improved scratch and mar resistance as the principal differentiating feature of 121-70M350.
The grade’s molded appearance can also benefit from its improved flow behavior, especially in complex parts where poor filling or weld-line appearance would otherwise create visual defects.
UV Resistance and Automotive Interior Use
Although automotive interiors are not continuously exposed to the same weathering conditions as exterior parts, sunlight passing through vehicle glazing can still create significant UV and heat exposure over a vehicle’s service life.
Santoprene 121-70M350 is described as UV resistant, which supports use in visible interior areas such as instrument-panel interfaces and windshield-adjacent components.
The black appearance is also appropriate for many interior sealing and gap-filler designs where designers want a visually unobtrusive transition between components.
UV resistance should be considered together with part design, pigment system, temperature exposure and OEM interior-aging requirements.
Why Choose Santoprene 121-70M350?
The strongest reason to choose Santoprene 121-70M350 is that it combines the processing efficiency of TPV with an application-specific focus on automotive interior appearance.
A general-purpose 70A TPV can provide flexibility and sealing performance, but it may not be optimized for visible scratch and mar resistance.
In contrast, Santoprene 121-70M350 is specifically positioned for parts where surface quality matters.
This is particularly useful for instrument-panel gap fillers, visible sealing interfaces and soft interior components.
Its Shore A 70 hardness gives the part enough firmness to maintain geometry while remaining flexible enough to absorb dimensional variation between adjacent trim components.
The approximately 480% elongation allows substantial movement without brittle fracture.
The 6.2 MPa stress at break provides useful mechanical strength for handling, assembly and service.
The material’s shear-dependent behavior supports mold filling in complex geometries.
Celanese also states that it is designed for injection at lower molding temperatures or lower injection pressures, making the grade attractive for difficult tools and large or appearance-sensitive components.
UV resistance supports long-term interior use near windshields and other glazed areas.
The low density of 0.930 g/cm³ can help reduce part mass compared with denser rubber systems.
For manufacturers seeking a 70A black TPV specifically for automotive interior gap fillers and scratch-resistant visible components, Santoprene 121-70M350 is much more targeted than a generic 70A TPV.
Processing Guidelines for Santoprene 121-70M350
Santoprene 121-70M350 is primarily designed for injection molding and multi-injection molding.
Recommended Starting Conditions
| Processing Parameter | Guidance |
|---|---|
| Drying Temperature | 80°C |
| Drying Time | 3 hours |
| Optimum Melt Temperature | 215°C |
| General TPV Processing Window | 175–230°C |
Celanese recommends desiccant drying for approximately 3 hours at 80°C.
The manufacturer describes Santoprene TPV as having a broad processing window of approximately 175–230°C.
For Santoprene 121-70M350, the current optimum melt-temperature value is approximately 215°C.
Injection Molding Behavior
The grade is explicitly designed for fast and easy injection molding, including complex geometries.
Its shear-dependent rheology means flow improves as shear rate increases.
Important process variables include injection speed, screw speed, gate dimensions, runner design, back pressure, melt temperature, mold temperature, packing pressure, venting, cooling time, texture depth and surface-finish requirement.
For appearance-critical parts, the processor should pay special attention to gate location, weld lines, venting and mold-surface finish.
Lower Temperature / Lower Pressure Processing
Celanese specifically states that Santoprene 121-70M350 is designed to be injected at lower molding temperatures or lower injection pressures.
This can be useful when the tool has complex geometry, the part contains long or thin flow paths, the mold is sensitive to high clamp/injection pressure, surface appearance is critical, reduced thermal load is beneficial or multi-material molding is involved.
Material Compatibility
Santoprene TPV is incompatible with acetal (POM) and PVC.
When a molding machine has previously processed POM or PVC, the barrel, screw, hot runner and feed system should be properly purged before introducing Santoprene TPV.
Automotive OEM References for Santoprene 121-70M350
Current Celanese material data lists the following OEM specification references:
| OEM | Specification |
|---|---|
| Mercedes-Benz Group / Daimler | DBL 5562 |
| Volkswagen Group | TL 526 22 – MDX1/12 |
| Volkswagen Group | VW 50123 |
| Volkswagen Group | VW 50180 |
These references support the grade’s positioning as an automotive interior and sealing material.
For production programs, the exact current OEM approval status should be matched to the required part specification and drawing.
Santoprene 121-70M350 vs. Santoprene 121-70B260
Both grades are black Santoprene TPVs with hardness close to 70 Shore A, but they are designed for very different automotive functions.
| Feature | Santoprene 121-70M350 | Santoprene 121-70B260 |
|---|---|---|
| Main Positioning | Automotive interior | Automotive weatherseal corner molding |
| Main Feature | Improved scratch & mar resistance | Low COF + bonding to TPV/EPDM |
| Typical Application | Gap fillers / visible interior seals | Corner molding / end caps |
| Shore A Hardness | 70 | Approx. 68 |
| Elongation at Break | 480% | Approx. 520% |
| Stress at Break | 6.2 MPa | Approx. 6.4 MPa |
| Stress @ 100% Elongation | 2.6 MPa | Approx. 2.6 MPa |
| Compression Set, 70°C | 40% | Approx. 49% |
| Density | 0.930 g/cm³ | Approx. 0.910 g/cm³ |
| Special Surface Property | Scratch / mar resistance, appearance | Low coefficient of friction |
| Bonding Focus | General sealing / interior | Designed to bond to TPV and EPDM |
Choose Santoprene 121-70M350 when the priority is visible interior appearance, gap filling and scratch resistance.
Choose Santoprene 121-70B260 when the priority is automotive weatherseal corner molding, low friction and bonding to TPV or vulcanized EPDM.
Related Products
Santoprene 121-65M300 – Black high-flow TPV with low-volatiles positioning for appearance-sensitive molding.
Santoprene 121-80M300 – Higher-hardness black high-flow TPV with low-volatiles positioning.
Santoprene 8211-85M350 – Colorable M350-family TPV positioned for improved scratch and mar resistance.
Santoprene 121-70B260 – Black automotive corner-molding TPV with low coefficient of friction and improved bonding to TPV and EPDM.
View More TPV Thermoplastic Vulcanizates →
Technical Documents for Santoprene 121-70M350
| Document Type | Description |
|---|---|
| TDS | Grade-specific physical, mechanical and processing data |
| SDS | Safety Data Sheet |
| Automotive Grade Slate | Celanese automotive application and grade-positioning guide |
| Product Finder | Santoprene TPV grade comparison |
| OEM Information | Mercedes-Benz and Volkswagen Group specification references |
| Processing Guide | Injection-molding guidance for Santoprene TPV |
| COA | Batch-specific quality information where available |
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FAQ About Santoprene 121-70M350
Q1: What is Santoprene 121-70M350?
Santoprene 121-70M350 is a black, UV-resistant 70 Shore A TPV from Celanese designed mainly for automotive interior gap fillers, sealing parts and components requiring good surface appearance and improved scratch/mar resistance.
Q2: What is the hardness of Santoprene 121-70M350?
The current Shore A hardness is approximately 70.
Q3: What is the main advantage of Santoprene 121-70M350?
Its key differentiation is improved scratch and mar resistance combined with good molded appearance and high-flow injection molding performance.
Q4: What is the elongation at break?
Current Celanese data lists approximately 480% elongation at break.
Q5: What is the tensile stress at break?
The current value is approximately 6.2 MPa.
Q6: What is the density of Santoprene 121-70M350?
The current ISO density is approximately 0.930 g/cm³.
Q7: Is Santoprene 121-70M350 UV resistant?
Yes. Celanese describes the grade as a UV-resistant black TPV.
Q8: Can Santoprene 121-70M350 be injection molded?
Yes. Injection molding is its primary processing method, and the grade is specifically designed for fast, easy filling of complex geometries.
Q9: What processing temperature is recommended?
The current optimum melt temperature is approximately 215°C. Celanese also gives a broad Santoprene TPV processing window of approximately 175–230°C.
Q10: What is the difference between Santoprene 121-70M350 and 121-70B260?
Santoprene 121-70M350 is optimized for automotive interior appearance and scratch/mar resistance, while 121-70B260 is optimized for weatherseal corner molding, low coefficient of friction and bonding to TPV and EPDM.
Request Santoprene 121-70M350 Price & Technical Support
For pricing, availability, technical documents or application support for Santoprene 121-70M350, please provide:
- Required quantity
- Destination country or port
- Automotive interior application
- Gap filler, seal or molded-part geometry
- Required Shore hardness
- Surface texture and gloss requirement
- Scratch / mar requirement
- UV exposure requirement
- Part dimensions
- Injection-molding machine information
- Mold type and cavity count
- Required OEM specification
- TDS, SDS or COA requirement
- Sample requirement, if applicable
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