**2.6 Improvements in plastisol production**

Plastisols take a special place in processing of PVC since they are moulded as liquids or pastes rather than in a thermoplastic state. The solidication, the so called gelling, takes place at the end of molding through heat treatment at 120 to 200°C (Franck & Knoblauch, 2005).

In making these pastes the processing behaviour can be signicantly improved in many respects by the substitution of around 10% of the plasticizer with Flexidone 100 (octyl pyrrolidone). Degassing at the end of mixing and homogenizing the plastisol mixture is intended to minimize defects in the subsequent processing of the pastes. Flexidone 100 is amongst the surfactants with the highest dynamic wetting properties. This means that a partial substitution is sufficient in order to reduce foaming to a minimum and thereby signicantly shorten degassing cycles.

During the processing of PVC plastisols the gelling temperature is of particular interest. Therefore substantial efforts have been made in order to lower the gelling temperature. It is determined via measurements of the complex viscosity against temperature. After an initial drop once gelling begins there is a rise in the viscosity of more than four orders of magnitude. The gelling temperature is the point of inection on the curve. Figure 9 shows viscosity measurements of plastisols with 50 parts Vestinol 9 (DINP) and plastisols, in which 1, 3, 5 and 10 parts of Vestinol 9 were replaced by Flexidone 100. Due to the signicantly higher dissolving power of Flexidone 100 the gelling temperature can be signicantly reduced. Each part of Flexidone 100 causes approximately 2°C drop so that a blend of Vestinol 9/Flexidone 100 at a ratio of 40/10 reduces the gel temperature by 20°C. The viscosity prole is at the same time not affected at all and only after storage for a long time a small increase in viscosity could be seen.

Fig. 9. Gelling curves of PVC plastisols (50 phr plasticizer) with various mixtures of Vestinol 9 (registered trade mark of Evonik for DINP)/Flexidone100.

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.

#### **3. Mixed plasticizer systems**

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 soybean oil) as well as to primary plasticizers like DOA

decreases the

8 Recent Advances in Plasticizers

82,6

Shore A (40 phr plast.) Shore A (60 phr plast.)

91,7

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

end of molding through heat treatment at 120 to 200°C (Franck & Knoblauch, 2005).

Therefore the formulation costs can be lowered in many applications using Flexidones with

Plastisols take a special place in processing of PVC since they are moulded as liquids or pastes rather than in a thermoplastic state. The solidication, the so called gelling, takes place at the

In making these pastes the processing behaviour can be signicantly improved in many respects by the substitution of around 10% of the plasticizer with Flexidone 100 (octyl pyrrolidone). Degassing at the end of mixing and homogenizing the plastisol mixture is intended to minimize defects in the subsequent processing of the pastes. Flexidone 100 is amongst the surfactants with the highest dynamic wetting properties. This means that a partial substitution is sufficient in order to reduce foaming to a minimum and thereby

During the processing of PVC plastisols the gelling temperature is of particular interest. Therefore substantial efforts have been made in order to lower the gelling temperature. It is determined via measurements of the complex viscosity against temperature. After an initial drop once gelling begins there is a rise in the viscosity of more than four orders of magnitude. The gelling temperature is the point of inection on the curve. Figure 9 shows viscosity measurements of plastisols with 50 parts Vestinol 9 (DINP) and plastisols, in which 1, 3, 5 and 10 parts of Vestinol 9 were replaced by Flexidone 100. Due to the signicantly higher dissolving power of Flexidone 100 the gelling temperature can be signicantly reduced. Each part of Flexidone 100 causes approximately 2°C drop so that a blend of Vestinol 9/Flexidone 100 at a ratio of 40/10 reduces the gel temperature by 20°C. The viscosity prole is at the same time not affected at all and only after storage for a long time a

remarkably increased filler loads.

**2.6 Improvements in plastisol production** 

signicantly shorten degassing cycles.

small increase in viscosity could be seen.

Flexidone 300 DINP

71,8

85,6


and increases the


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

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.

Flexidone™ – A New Class of Innovative PVC Plasticizers 11

As it can be seen in figure 12 the hardness increases with increasing fatty acid ester content.

Most interestingly all mixtures with a ratio between 3:1 and 1:3 show cold foldability temperatures of -70°C and below! Therefore the costs can be reduced by mixing Flexidone's with fatty acid esters while improving tensile properties and still benefit from excellent cold

> Flexidone 300 / Fatty acid ester Felxidone 500 / Fatty acid ester

DINP

Flexidone 3-1 1-1 1-3

Fig. 12. Indentation hardness for Flexidone 300 and Flexidone 500 in mixtures with a fatty

As a conclusion of these results ISP commercialized different Flexidone / fatty acid ester – blends such as Flexidone 350FE, Flexidone 333FE, Flexidone 550FE and Flexidone 533FE. Flexidone FE yields stable, low-viscosity plastisols with excellent shelf life and desirable fast-fusing properties. This combination enables the system to be used in various production methods such as extrusion, calendaring and injection molding. Additionally they provide low-viscosity plastisols with good gelling properties. As figure 13 indicates, of various samples of plastisol formulations, those with Flexidone 333FE and 533FE exhibit the best viscosity stability after 28 days, enlarging the processing window for many product

In addition to better viscosity stability, Flexidone FE improves the gelling behaviour of PVC products, which affects its strength. In figure 14, the gelling rates of Flexidone 333FE and

350FE were the fastest compared with other Flexidone grades and a DINP.

55

60

65

**Shore A**

acid ester in comparison to DINP.

manufacturers.

70

75

80

But all examined mixtures show still higher plasticizing efficiency than DINP.

flexibility.

Fig. 10. Tensile strength for Flexidone 300 and Flexidone 500 in mixtures with a fatty acid ester.

Fig. 11. Elongation at break for Flexidone 300 and Flexidone 500 in mixtures with a fatty acid ester.

Flexidone 3-1 1-1 1-3

Fig. 10. Tensile strength for Flexidone 300 and Flexidone 500 in mixtures with a fatty acid

Flexidone 300 / Fatty acid ester Felxidone 500 / Fatty acid ester

Flexidone 300 / Fatty acid ester Felxidone 500 / Fatty acid ester

Flexidone 3-1 1-1 1-3

Fig. 11. Elongation at break for Flexidone 300 and Flexidone 500 in mixtures with a fatty acid

0

0

50

100

150

**Elongation at break %**

200

250

300

350

2

4

6

8

**Tensile Strength MPa**

ester.

ester.

10

12

14

16

As it can be seen in figure 12 the hardness increases with increasing fatty acid ester content. But all examined mixtures show still higher plasticizing efficiency than DINP.

Most interestingly all mixtures with a ratio between 3:1 and 1:3 show cold foldability temperatures of -70°C and below! Therefore the costs can be reduced by mixing Flexidone's with fatty acid esters while improving tensile properties and still benefit from excellent cold flexibility.

Fig. 12. Indentation hardness for Flexidone 300 and Flexidone 500 in mixtures with a fatty acid ester in comparison to DINP.

As a conclusion of these results ISP commercialized different Flexidone / fatty acid ester – blends such as Flexidone 350FE, Flexidone 333FE, Flexidone 550FE and Flexidone 533FE. Flexidone FE yields stable, low-viscosity plastisols with excellent shelf life and desirable fast-fusing properties. This combination enables the system to be used in various production methods such as extrusion, calendaring and injection molding. Additionally they provide low-viscosity plastisols with good gelling properties. As figure 13 indicates, of various samples of plastisol formulations, those with Flexidone 333FE and 533FE exhibit the best viscosity stability after 28 days, enlarging the processing window for many product manufacturers.

In addition to better viscosity stability, Flexidone FE improves the gelling behaviour of PVC products, which affects its strength. In figure 14, the gelling rates of Flexidone 333FE and 350FE were the fastest compared with other Flexidone grades and a DINP.

Flexidone™ – A New Class of Innovative PVC Plasticizers 13

 Flexidone 333FE can be used as primary plasticizer; about 15% more efficient than other systems; has lower plastisol viscosity than 350FE and stays stable even after longer

Flexidone 550FE can be used as primary plasticizer with gelling properties similar to

Flexidone 533FE for very-low-viscosity plastisols; can also be stored for very long time.

333FE but at a lower viscosity with higher clarity and lower volatility.

Fig. 14. Gelling curves of Flexidone FE Grades and DINP.

be seen. All mixtures have a total plasticizer content of 60 phr.

Similar experiments as with the Flexidone/fatty acid ester-systems were performed for the plasticizer systems Flexidone/chlorinated ester. In figure 15 and 16 the effect of Flexidone 300 and 500 on the tensile strength and elongation at break in mixtures with a Cl-ester can

The results prove the superior compatibility of this system with good mechanical properties in all concentrations up to 75% Cl-ester. Especially the 1:1-mixture with Flexidone results in

**3.2 Flexidone-chlorinated ester-system** 

storage.

Lower volatile.

The Flexidone FE grades behaviour in plastisol can be summed up as:

 Flexidone 350FE offers fast and low-temperature gelling, improved transparency and homogeneity. As a primary plasticizer for plastisols (for immediate processing), it is an extremely fast fusing system requiring about 30% less use than standard plasticizers.

Fig. 13. Viscosity of various plastisol formulations with Flexidone FE Grades compared with

 Flexidone 350FE offers fast and low-temperature gelling, improved transparency and homogeneity. As a primary plasticizer for plastisols (for immediate processing), it is an extremely fast fusing system requiring about 30% less use than standard plasticizers.

The Flexidone FE grades behaviour in plastisol can be summed up as:

DINP.


Fig. 14. Gelling curves of Flexidone FE Grades and DINP.

#### **3.2 Flexidone-chlorinated ester-system**

Similar experiments as with the Flexidone/fatty acid ester-systems were performed for the plasticizer systems Flexidone/chlorinated ester. In figure 15 and 16 the effect of Flexidone 300 and 500 on the tensile strength and elongation at break in mixtures with a Cl-ester can be seen. All mixtures have a total plasticizer content of 60 phr.

The results prove the superior compatibility of this system with good mechanical properties in all concentrations up to 75% Cl-ester. Especially the 1:1-mixture with Flexidone results in

Flexidone™ – A New Class of Innovative PVC Plasticizers 15

Although the plasticizing efficiency reduces with increasing Cl-ester content, even Flexidone/Cl-ester-mixtures with very high Cl-ester content show Shore A values similar to

Analogue to the indentation hardness results the cold flexibility in the mixtures with Clester is slightly inferior to the corresponding Flexidone/fatty acid ester system. Still all

> Flexidone 300 / Cl-ester Felxidone 500 / Cl-ester

Fig. 17. Indentation hardness for Flexidone 300 and Flexidone 500 in mixtures with a Cl-

Over the last few years a significant number of product trials have been performed to test

Shoe soles are just one example for various soft-PVC applications ISP was asked to come up

As a substitute for the DINP/CP-system (with Shore A 53) we could offer a Flexidone/ESO system with 80 phr ESO and 20 phr Flexidone 300 showing the same softness (Shore A 50) and lower processing temperature even with a lower plasticizer content and an increased

Flexidone in existing formulations or in new product developments successfully.

with alternative formulations. Following two formulations will be presented here:

one formulation with 80 phr DINP, 40 phr chlorine paraffin and 20 phr CaCO3 and

Flexidone 1-1 1-3 DINP

measured samples show cold foldability temperatures of -40°C and below.

a sample with the same amount of DINP (see figure 17).

**Shore A**

55

ester in comparison to DINP.

**4. Product developments** 

one formulation with 80 phr DOA.

amount of CaCO3 (see Table 1).

**4.1 Shoe soles** 

60

65

70

75

80

85

a rubber like behaviour with elongation at break values of over 500%. From this 500% elongation over 450% is elastic deformation and less than 50% is plastic deformation.

Fig. 15. Tensile strength for Flexidone 300 and Flexidone 500 in mixtures with a Cl-ester.

Fig. 16. Elongation at break for Flexidone 300 and Flexidone 500 in mixtures with a Cl-ester.

a rubber like behaviour with elongation at break values of over 500%. From this 500%

Flexidone 300 / Cl-ester Felxidone 500 / Cl-ester

Flexidone 300 / Cl-ester Felxidone 500 / Cl-ester

Flexidone 1-1 1-3

Fig. 16. Elongation at break for Flexidone 300 and Flexidone 500 in mixtures with a Cl-ester.

Flexidone 1-1 1-3

Fig. 15. Tensile strength for Flexidone 300 and Flexidone 500 in mixtures with a Cl-ester.

elongation over 450% is elastic deformation and less than 50% is plastic deformation.

**Tensile Strength MPa**

**Elongation at break %**

0

100

200

300

400

500

600

Although the plasticizing efficiency reduces with increasing Cl-ester content, even Flexidone/Cl-ester-mixtures with very high Cl-ester content show Shore A values similar to a sample with the same amount of DINP (see figure 17).

Analogue to the indentation hardness results the cold flexibility in the mixtures with Clester is slightly inferior to the corresponding Flexidone/fatty acid ester system. Still all measured samples show cold foldability temperatures of -40°C and below.

Fig. 17. Indentation hardness for Flexidone 300 and Flexidone 500 in mixtures with a Clester in comparison to DINP.
