Multi-Wall Sheet Extrusion: Resins
Resins are thermoplastic materials that offer a wide range of performance properties, including toughness, strength, and chemical resistance.
The specific grade you choose depends on the property requirements of the final application, the extrudability of the resin, and any secondary processing necessary.
Makrolon® Polycarbonates
Makrolon® 1243 and 1143 polycarbonate grades are suitable for multi-wall sheet extrusion. They have slightly different properties.
| Table 1. Grades of Makrolon® polycarbonate for multi-wall extrusion | |
| Grade | Properties |
| Makrolon® 1243 | Branched, UV stabilized with release agent |
| Makrolon® 1143 | Branched, UV stabilized with release agent, and high viscosity |
Makrolon® 1243 polycarbonate is the standard grade. With a melt volume flow rate (MVR) value of 6 cm³/10 min at 300°C under 1.2kg load, this grade is less viscous than Makrolon® 1143 resin, which has an MVR value of 3 cm³/10 min. Makrolon® 1243 resin, therefore, can be extruded at comparable melt viscosities and lower melt temperatures. Depending on your application, this may offer advantages in productivity and sheet quality.
The special rheological behavior of the branched grades gives the melt a high degree of stability as it is discharged from the die nozzle. This property makes these grades exceptionally suitable for applications in which calibration takes place in the course of the process, which is the case with multi-wall sheet extrusion.
Both branched polycarbonates grades have a greater melt strength than linear grades. This prevents the delicate ribs and thin inner layers of the multi-wall sheets from collapsing at economical extruding speeds.
In order to extrude good-quality multi-wall sheet with uniform thickness, the resins must have sufficiently high melt strength. The BMS polycarbonates resins are, therefore, high-viscosity grades.
Multi-wall sheets are often used for outdoor applications that require increased UV protection. This can be achieved by coextruding Makrolon® DP1-1852 polycarbonate, a plate-out UV concentrate, with Makrolon® 1243 and 1143 resins.
Makrolon® 1243 and 1143 grades are transparent polycarbonates, but can be supplied in other colors. Coloring the resins is also an option and is added with color master batches during extrusion.
To determine the grade you require, consider typical property requirements, such as fire-retardant properties, impact properties, weatherability, light transmission, chemical resistance, heat resistance, and stiffness. Secondary processes may include painting or printing.
You can find more information about most grades and standard values in Bayer product information bulletins. See http://bayermaterialsciencenafta.com/products/index.cfm.
If you have any questions about using Bayer resins for multi-wall sheet extrusion, you can reach the technical team at BMS using the Contact form.
