COVESTRO BAYBLEND T90 MF-20 PC/ABS
A detailed analysis of an engineering thermoplastic designed for exceptional stiffness and dimensional stability.
Executive Summary
This report provides a detailed technical analysis of BAYBLEND T90 MF-20 PC/ABS, an engineering thermoplastic produced by Covestro. This material is a rubber-modified blend of polycarbonate (PC) and styrene-acrylonitrile (SAN), distinguished by its 20% mineral filler content. This unique formulation imparts a combination of superior properties that make it a standout choice for specific applications.
BAYBLEND T90 MF-20 features excellent flow, a significantly reduced coefficient of thermal expansion, high stiffness, and good heat resistance. Its melt volume-flow rate (MVR) is 12 cm³/10min (at 260 °C and 5 kg load), and its tensile modulus is as high as 4900 MPa. The presence of mineral filler results in nearly isotropic thermal expansion and molding shrinkage behavior, which is critical for manufacturing large, flat parts requiring strict dimensional precision. The material is well-suited for structural components and housings in the automotive, electrical/electronics, appliance, and consumer goods sectors, where high rigidity, dimensional stability, and surface finish are paramount.
Material Overview and Compositional Analysis
Introduction to the Bayblend Product Family
BAYBLEND is the trade name used by Covestro for its line of amorphous thermoplastic polymer blends based on polycarbonate (PC) and acrylonitrile butadiene styrene copolymer (ABS) or rubber-modified PC and styrene-acrylonitrile (SAN) blends. The design philosophy behind this blend is to combine the advantages of both PC and ABS, providing a solution with a balanced set of properties. PC contributes high heat resistance, toughness, and excellent dimensional stability, while ABS (or SAN) provides improved processability, low-temperature impact strength, and better surface finish. By adjusting the proportions of the two components and adding modifiers and fillers, Covestro has created a wide portfolio of Bayblend products to meet various specific application needs.
Naming Convention and Grade Analysis
The designation BAYBLEND T90 MF-20 follows Covestro's internal conventions, with each part of the name revealing key characteristics of the material.
- Bayblend®: The brand name from Covestro, representing the family of PC and ABS/SAN blends.
- T-Series: Grades in this series typically denote general-purpose, non-flame retardant blends with high toughness, especially at low temperatures. It is worth noting that while "T90" and "T45" in other contexts (e.g., hop pellets) refer to "Type" and product weight, in Covestro's plastic grades, the "T" series signifies a class of engineering materials with a specific performance profile.
- MF: Stands for "Mineral-Filled".
- 20: This number indicates the filler content, meaning the grade contains 20% mineral filler.
Understanding this naming convention allows engineers to quickly identify the core features of the material and compare it with other grades within the same product family, such as glass-fiber-filled (GF) or flame-retardant (FR) grades.
Material Chemistry and Key Characteristics
The chemical composition of BAYBLEND T90 MF-20 is a carefully engineered formulation with a base of a "rubber-modified (PC+SAN) blend" and the addition of 20% mineral filler. This specific composition gives the material a range of key properties, including very good flow, a reduced coefficient of thermal expansion, high tensile modulus (i.e., high stiffness), good heat resistance, and excellent dimensional stability.
The inclusion of the mineral filler is directly responsible for these enhanced properties. Compared to unfilled grades, the filler significantly increases the material's stiffness, as evidenced by its high tensile modulus of 4900 MPa. The filler also directly contributes to a reduced coefficient of thermal expansion. A particularly noteworthy characteristic is the material's nearly isotropic thermal expansion and shrinkage behavior. Unlike materials with anisotropic fillers like glass fibers, BAYBLEND T90 MF-20 expands and shrinks almost uniformly in all directions. This is crucial for designing and molding large, flat parts, as it minimizes the warpage and internal stresses that typically result from uneven shrinkage.
Detailed Material Properties
This section provides a comprehensive data analysis of the key properties of BAYBLEND T90 MF-20, serving as a core reference for design and engineering decisions.
Physical and Rheological Properties
The material has a density of 1290 kg/m³ or 1.29 g/cc. This is higher than unfilled grades (e.g., BAYBLEND T65 HI has a density of 1110 kg/m³) and is a direct result of the 20% mineral filler content. The material's water absorption is very low, with an equilibrium value of 0.2% at 23 °C and 50% relative humidity, and a saturation value of 0.5%. This low absorption rate is a key advantage for maintaining dimensional stability in humid environments.
In terms of rheological properties, the material has a melt volume-flow rate (MVR) of 12 cm³/10min at 260 °C and a 5 kg load. For a filled grade, this value indicates "very good flow". The addition of fillers typically reduces a polymer's flowability, but BAYBLEND T90 MF-20's ability to maintain excellent flow suggests that Covestro's formulation is optimized to overcome the common limitations associated with fillers. This makes the material suitable for injection molding complex or thin-walled components.
Mechanical Properties
| Property | Value | Unit | Test Standard |
|---|---|---|---|
| Tensile Modulus | 4900 | MPa | ISO 527-1,-2 |
| Yield Stress | 60 | MPa | ISO 527-1,-2 |
| Yield Strain | 3.2 | % | ISO 527-1,-2 |
| Stress at Break | 50 | MPa | ISO 527-1,-2 |
| Strain at Break | 9 | % | ISO 527-1,-2 |
| Notched Izod Impact Strength (23 °C) | 20 | kJ/m² | ISO 180/A |
| Notched Izod Impact Strength (-30 °C) | 6 | kJ/m² | ISO 180/A |
| Unnotched Izod Impact Strength (23 °C) | 70 | kJ/m² | ISO 180/U |
| Unnotched Izod Impact Strength (-30 °C) | 50 | kJ/m² | ISO 180/U |
Thermal Properties
| Property | Value | Unit | Test Standard |
|---|---|---|---|
| Deflection Temp. under Load (1.80 MPa) | 111 | °C | ISO 75-1,-2 |
| Deflection Temp. under Load (0.45 MPa) | 127 | °C | ISO 75-1,-2 |
| Vicat Softening Temp. (50 N, 50 °C/h) | 128 | °C | ISO 306 |
| Vicat Softening Temp. (50 N, 120 °C/h) | 130 | °C | ISO 306 |
| Coeff. of Linear Therm. Expansion, parallel to flow | 40 | E-6/K | ISO 11359-1,-2 |
| Coeff. of Linear Therm. Expansion, normal to flow | 56 | E-6/K | ISO 11359-1,-2 |
Electrical Properties
| Property | Value | Unit | Test Standard |
|---|---|---|---|
| Relative Permittivity (1 MHz) | 3.2 | - | IEC 62631-2-1 |
| Relative Permittivity (100 Hz) | 3.3 | - | IEC 62631-2-1 |
| Dissipation Factor (1 MHz) | 32 | E-4 | IEC 62631-2-1 |
| Dissipation Factor (100 Hz) | 15 | E-4 | IEC 62631-2-1 |
| Volume Resistivity | >1×10¹³ or >1×10¹⁴ | Ω⋅m | IEC 62631-3-1 |
| Surface Resistivity | >1×10¹⁵ or >1×10¹⁶ | Ω | IEC 62631-3-2 |
| Electric Strength | 35 | kV/mm | IEC 60243-1 |
| Comparative Tracking Index (CTI) | 225 | - | IEC 60112 |
Processing and Molding Guidelines
To ensure successful injection molding and high-quality parts, adhering to proper processing guidelines is crucial.
Preprocessing: Drying Recommendations
The material must be pre-dried before injection molding, with a maximum permissible moisture content of 0.02%. Strict moisture control is essential because the PC component of the blend is sensitive to hydrolysis. Even a small amount of moisture can trigger a hydrolytic reaction during high-temperature processing, leading to polymer chain degradation. This degradation can weaken the material's mechanical properties, such as tensile strength and impact toughness, and may cause aesthetic defects like silver streaks or bubbles in the finished part. The recommended drying temperature is 100-110 °C for 2-4 hours in a dry air dryer. This drying temperature is deliberately set below the material's Vicat softening temperature (128-130 °C) to prevent the granules from melting or clumping together.
Injection Molding Parameters
| Property | Value | Unit |
|---|---|---|
| Predrying Temperature | 100 - 110 | °C |
| Predrying Time | 2 - 4 | h |
| Max. Moisture Content | ≤ 0.02 | % |
| Melt Temperature Range | 240 - 280 | °C |
| Standard Melt Temperature | 270 | °C |
| Mold Temperature Range | 70 - 100 | °C |
| Standard Mold Temperature | 80 | °C |
| Injection Velocity | 240 | mm/s |
| Hold Pressure (% of Injection Pressure) | 50 - 75 | % |
| Back Pressure (specific) | 50 - 150 | bar |
| Peripheral Screw Speed | 0.05 - 0.2 | m/s |
| Shot-to-Cylinder Size | 30 - 70 | % |
| Vent Depth | 0.025 - 0.075 | mm |
Performance Analysis and Application Suitability
Advantages and Key Performance Differentiators
BAYBLEND T90 MF-20 stands out due to its unique balance of properties. It combines the high toughness and heat resistance of PC with the processability of ABS, while gaining additional benefits from its mineral filler content. The material's greatest advantage is its superior dimensional stability. Thanks to its low and nearly isotropic coefficient of linear thermal expansion and its very low water absorption, it is exceptionally suitable for applications requiring high dimensional precision, such as large, complex enclosures or structural components. Furthermore, unlike glass-fiber-filled grades, mineral-filled BAYBLEND T90 MF-20 can produce parts with a "Class A, low gloss surface," which is essential for aesthetically demanding applications like automotive interior and exterior parts.
Performance Comparison
| Property | T90 MF-20 | T65 HI | FR3000 |
|---|---|---|---|
| Tensile Modulus (MPa) | 4900 | 2000 | 2700 |
| Notched Izod Impact Strength (kJ/m²) | 20 (23°C) | 48 (23°C) | 45 (23°C) |
| Vicat Softening Temp. (°C) | 128 | 118 | 95 |
| Melt Volume-flow Rate (MVR) cm³/10min | 12 | 5 | 24 |
| CLTE, parallel to flow (E-6/K) | 40 | 90 | 76 |
| UL 94 Flammability Rating | HB | HB | V-0 |
Typical Applications and Case Studies
Based on its performance characteristics, BAYBLEND T90 MF-20 is a preferred material for the following sectors:
- Automotive Industry: Suitable for structural components, interior and exterior panels, and other applications where low warpage and superior surface finish are needed. Its low CLTE property makes it particularly useful for large panels like roof spoilers.
- Electronics/IT Industry: Ideal for housings and chassis requiring high dimensional stability and stiffness.
- Appliance and Consumer Goods: Used for components that demand high strength and heat resistance.
Regulatory and Safety Information
Flame Retardancy and Safety Ratings
The material has a UL 94 HB flammability rating at a tested thickness of 0.8 mm. A UL 94 HB rating signifies that the material burns slowly in a horizontal test, which is distinct from the V-0 rating achieved by some Bayblend grades. A V-0 rating means the material is self-extinguishing within a specific time in a vertical test. This difference is critical for product safety and regulatory compliance, especially in electronic or electrical applications.
Environmental and Health Compliance
RoHS Compliance: The provided data does not explicitly state whether BAYBLEND T90 MF-20 is RoHS compliant. The lack of information does not mean it is non-compliant. As a best practice, users should directly consult Covestro, an authorized distributor like ALBIS or M. Holland, or their official website for a formal compliance statement or certificate.
REACH SVHC Compliance: Similarly, the material's data does not specifically mention if it contains any declarable Substances of Very High Concern (SVHCs). Covestro states that it provides up-to-date SVHC information and advises customers to consult the specific product's Safety Data Sheet (SDS).
Food Contact Safety: The provided information does not indicate if BAYBLEND T90 MF-20 is compliant with food contact safety standards. While general ABS is often considered food-safe, the presence of a mineral filler means a specific food-grade formulation is required. Without a clear certification from Covestro, the material should not be used in food contact applications.
Conclusion
BAYBLEND T90 MF-20 is an engineered thermoplastic designed for applications that demand high stiffness and exceptional dimensional stability. Its core value lies in the 20% mineral filler, which delivers a low and nearly isotropic coefficient of thermal expansion, giving it a unique advantage in manufacturing large, flat parts with tight dimensional tolerances. The material also maintains good processing flow, addressing a common challenge with filled materials.
However, selecting this material involves a strategic performance trade-off. While it outperforms unfilled grades in stiffness and heat resistance, it sacrifices some notched impact toughness. Furthermore, its UL 94 HB flammability rating means it is not suitable for electrical or electronic applications that require a higher V-0 rating. In summary, BAYBLEND T90 MF-20 is a cost-effective solution, particularly well-suited for non-flame-retardant applications in the automotive, IT, and appliance sectors where high structural performance and dimensional stability are the top priorities.