**2.5 Properties of highly filled systems**

Fillers are used in plasticized PVC to reduce costs, and also to facilitate a special change in properties so that the compound largely meets the requirements of the end products (Hohenberger, 2001). Among the fillers, calcium carbonate, with a worldwide market share of approximately 70%, plays the dominant role. For plasticized PVC, depending on the application (cable, floor covering, profiles, films), uncoated or coated calcium carbonate grades, with different particle sizes, can be used. For all experiments a stearic acid coated calcium carbonate with a d50% value of 2.4 µm and a top cut of 20 µm (Omya BSH) was used.

In highly filled systems, e.g. with a calcium carbonate content of 150 phr important mechanical properties, like the tensile strength, can easily drop down to less than 50%, compared to the unfilled systems if a standard plasticizer like DINP is used. For a highly filled system with Flexidone 300 as plasticizer, all essential mechanical properties vary only insignificantly from the unfilled system. As shown in Figure 8, softness of the Flexidone 300 formulation decreases only slightly in comparison to DINP even with a filler load of 100 phr Calcium carbonate.

Flexidone™ – A New Class of Innovative PVC Plasticizers 9

45 phr Vestinol 9 + 5 phr Flexidone 100

40 phr Vestinol 9 + 10 phr Flexidone 100

47 phr Vestinol 9 + 3 phr Flexidone 100

9 (registered trade mark of Evonik for DINP)/Flexidone100.

soybean oil) as well as to primary plasticizers like DOA

30 40 50 60 70 80 90 100 110

50 phr Vestinol 9

49 phr Vestinol 9 + 1 phr Flexidone 100

**Temperature [°C]**

Fig. 9. Gelling curves of PVC plastisols (50 phr plasticizer) with various mixtures of Vestinol

Comparable results were also found for blends with Hexamoll DINCH, but the initial viscosities were much lower and the viscosity after prolonged storage rose insignificantly.

Through these outstanding processing and physical properties and the extremely high compatibility, Flexidones enhance the tolerance level of low cost secondary plasticizers in PVC so that these could be used in very high amounts. Adding Flexidone 300 or 500 to secondary plasticizers like fatty acid esters, chlorinated Paraffines/esters, ESO (epoxidized

In figure 10 and 11 the effect of Flexidone 300 and 500 on the tensile strength and elongation at break in mixtures with a fatty acid ester can be seen. All mixtures have a total plasticizer content of 60 phr. The results prove the excellent compatibility of this system with good

mechanical properties in all concentrations up to 75% fatty acid ester.

1

**3. Mixed plasticizer systems** 

10

100

1.000

**Complex viskosity [Pas]**

decreases the

 indentation hardness cold flexibility temperature processing temperature

clarity / transparency.

**3.1 Flexidone-fatty acid ester-system** 

 processing time and increases the compatibility gelling speed

10.000

100.000

Fig. 8. Shore A-values with Flexidone 300 and DINP, each filled with 100 phr CaCO3.

Therefore the formulation costs can be lowered in many applications using Flexidones with remarkably increased filler loads.
