additives | PVC
Gloss retention was monitored over 1,500 hours. Cleartack W-110 resin gave better gloss retention than an acrylic processing aid (see Figure 6). Weathering was tested using a QUV with method G154 cycle 1/0; gloss was tested in accordance with ASTM D523. Marozsan also notes that “with the recent supply
Figure 4: Results of static stability tests of various stabiliser systems in transparent applications Source Chemson
Figure 5: Results from dynamic stability tests of various stabiliser systems in transparent applications
Source: Chemson
a narrower process window than other polymers – hence the need for processing aids. These are most commonly acrylic-based, but Cleartack W resins are low molecular weight polymers based on the polymeri- sation of aromatic hydrocarbons. “Using Cleartack W instead of a traditional acrylic processing aid improves thermal stability, impact strength, and surface quality,” the company says. Offered in pastilles and a new powdered form,
Cleartack W-110 has a lower polarity than PVC so some incompatibility is expected, says Global Business Development Manager Anthony Marozsan. ‘This incompatibility provides a slip layer to achieve flow but not too much that it would block fusion. This means that Cleartack W-110 provides some lubricating effect while acting as a processing aid.” In a recent study, researchers at Total Cray Valley
extruded various compounds into sheets and then cut these into strips for testing resistance to weathering.
Figure 6: 60° gloss measurements as moulded and after 1,500 hours of accelerated weathering – Cleartack W-100 versus an acrylic-based alternative Cleartack W-110
As moulded
After weathering Retention
Source:Total Cray Valley 20 PIPE & PROFILE EXTRUSION | July/August 2017
77.2 23.1 30%
Acrylic 73.9 13.1 18%
issues for acrylic monomers, we see more customers looking for high performance alternatives such as Cleartack W-110, which are in supply.” In an earlier study, Cleartack W-110 was shown to
reduce torque and shear heating (table 2). It also showed slightly better physical properties such as tensile and modulus than standard lubricating acrylic. Meanwhile, Valtris Specialty Chemicals has added two
new lubricants for PVC processing to its Petrac line. Petrac 200 is an NSF/PPI potable water pipe formulation- approved 165 melt point lubricant based on Fischer- Tropsch (FT) wax technology. Valtris says that improve- ments in refinery technology means fewer paraffin wax by-products are generated, allowing the development of “engineered” FT waxes such as Petrac 200 that are extremely consistent in composition. “This technology is a perfect complement to Valtris’s
metallic stearate product line for rigid PVC,” said Peggy Schipper, Business Director Lubricants for Valtris Specialty Chemicals. The other new addition is Petrac 230. This is a high
density oxidised polyethylene wax (HD OxPE) designed to complement the company’s existing 215 grade, which has been an industry standard metal release lubricant for years. In addition to its ability to provide metal release properties at low levels, Petrac 230 acts also acts as a fusion promoter to deliver more controlled processing of highly filled and difficult-to-fuse PVC formulations.
Click on the links for more information: ❙
www.reagens-group.com ❙
www.chemson.com ❙
www.clariant.com ❙
www.baerlocher.com ❙
www.crayvalley.com ❙
www.valtris.com
Figure 7: Fusion performance – Cleartack W110 versus an acrylic-based alternative
Fusion Time (s) Fusion Torque (mg)
Fusion Temperature (°C) Source: Total Cray Valley
Cleartack W-110 Acrylic 60
62
1590 170
1740 177
www.pipeandprofile.com
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