1. New Class of Liquid Phosphite Stabilizers The Green Solution
Dr. Michael Jakupca
Dr. Don Stevenson, Jacob Lance, Nina Ruegg Dover Chemical Corporation
SPE Polyolefins Conference 2011
Houston, Texas

2. Polyolefin Stabilizers
Most polyolefin stabilizer packages include a primary antioxidant (such as a hindered phenolic) and a secondary antioxidant (usually an organophosphite)

3. Common Antioxidants for LLDPE
TNPP (trisnonylphenyl phosphite)
Commodity Solid Phosphite (SP-1) P O C 9 H 1 3 P O 3
High Performance Solid Phosphite (SP-2)
Commodity Hindered Phenolic (AO-1) C 18 H O - 2 37

4. Commodity Phosphite Stabilizers
TNPP and SP-1 are the most widely used commercially available phosphites
Good cost-performance
Good hydrolytic stability
Globally registered
Global indirect food contact clearance
TNPP is a liquid, SP-1 is a solid

5. Trisnonylphenyl Phosphite (TNPP)
TNPP is in many ways the ideal phosphite. It offers several advantages over SP-1
TNPP is the most cost effective phosphite available
TNPP does not show compatibility/bloom issues in LLDPE applications, especially film
SP-1 can bloom at >1,000ppm in certain LLDPE resins/applications
The use of TNPP is often dictated by the type of additive handling unit, solid or liquid handling
Currently, TNPP is the only liquid phosphite available with global indirect food contact clearance for all polymer applications (GRAS)

6. TNPP Global Status
TNPP has been used safely in food contact polymers for more than 30 years. There are no governmental mandated use restrictions on TNPP
TNPP can be used in all food contact polymers in the US without limitations (21 CFR , Antioxidants and/or Stabilizers for Polymers) - GRAS
“The quantity used shall not exceed the amount reasonably required to accomplish the intended technical effect.”
TNPP also approved for use in the EU
Broad approval and high SML
Specific Migration Limit (SML) = 30 mg/kg

7. TNPP in EU Risk Assessment
2001 European Union NP Assessment discussed TNPP. With regards to human health concerns, the EU concluded there were no consumer exposure scenarios, including for TNPP, of concern given low exposure and limited mammalian toxicity concerns
TNPP is currently in the final stages of an environmental EU risk assessment

8. TNPP Replacement?
There are many types of commercially available phosphites…
R1=R2=R3=alkyl Alkyl Phosphites
R1=R2=R3=aryl Aryl Phosphites
R1R2R3=alkyl/aryl Alkyl/Aryl RO OR P OR
Examples R = phenyl, 2-ethylhexyl, isodecyl, nonylphenyl

9. Phosphite : Ligand Choice
The structure of the ligand has a large effect on phosphite properties
Physical form: solid or liquid
Hydrolytic stability
Compatibility in the polymer
Activity-performance
Volatility-thermal stability
Cost

10. Hydrolytic Stability
Phosphites can be hydrolyzed/degraded when exposed to water, especially under acidic environments. O ||
HP(OR)2 + ROH
P(OR)3 + H2O O ||
HP(OR) H2O
H3PO ROH
Acidic =“ Black Specks”

11. Hydrolytic Stability Hydrolysis resistance trend
Alkyl < Akyl-Aryl < Aryl < Hindered Aryl
Least Most
Hydrolytic Stability Hydrolytic Stability

12. Hydrolytic Stability (Aryl>Alkyl)
(Phosphites exposed to 60°C, 85% Humidity)

13. Structure of Ligands Effect Hydrolytic Stability
Phosphites exposed to 60°C, 85% Humidity

14. Hydrolytic Stability (Effect of Steric Hindrance)
Phosphite A
Phosphite B
Phosphite C
Hours to Failure
% Hydrolyzed
Phosphite A
<10
>50%
Phosphite B
~48
Phosphite C
>2000
<5%
Neat Phosphites Exposed to 40°C & 85% Humidity

15. Phosphite Activity (Depends on Polymer)
Peroxide decomposition
P(OR)3 + R’OOH O=P(OR) R’OH
Arbuzov and related reactions
P(OR)3 + Cl-R’ (labile) (RO)2P(O)-R’ RCl
P(OR)3 + HCl (RO)2P(O)H RCl
2P(OR)3 + ZnCl Zn[OP(OR)2] RCl
Hydrolysis
P(OR)3 + H2O (RO)2P-OH ROH
Addition reaction
P(OR)3 + -C=C O=P(OR)2-C-C-R
Mostly
For PVC

16. Competitive Oxidation : Alkyl vs. Aryl
In general, Alkyl Phosphites are more active at scavenging hydroperoxides than Aryl Phosphites
Aryl Phosphite
Rate of
Oxidation
Alkyl
Phosphite
Concentration versus time in paraffin solvent at 200°C

17. Phosphite Polyolefin Stabilizers
Polyolefin phosphite stabilizers are generally composed of hindered aryl ligands (alkylphenols)
Hydrolytic stability is needed to prevent black specks and poor material handling
% Phosphorus is key to performance
Two phosphites dominate the commodity market P O C 9 H 1 3 P O 3
Liquid Solid

18. Compatibility
The choice of alkylphenol also dictates the compatibility of the phosphite in the resin
Especially important is compatibility in LLDPE during cast film processing (highly amorphous)
Lack of compatibility results in plate-out on equipment as well as post process bloom or surface exudation
One of drawbacks of SP-1

19. Compatibility By Gloss Measurements
It is known that SP-1 can bloom in LLDPE applications at levels above 1000ppm. The bloom can be accurately detected by this technique.
TNPP does not bloom because of the greater solubility of nonylphenol.
Compatibility Limit
For SP-1 in this
Resin is <1,200ppm P O 3

20. Antibloom Packages
Antibloom agents have been developed that prevent the bloom of phosphite SP-2
Cleared for use in food contact applications

21. Alkylphenols in the “Spotlight”
Monosubstituted para-alkylphenols as a class
Monoalkylphenols from C4 to C12 have shown low levels of petri-dish ED activity
Butyl-, octyl-, nonylphenol, (Bisphenol A)
Petri dish experiments are a screening tool, and are extremely sensitive, do NOT represent in vivo activity
This is a perception issue, not a safety issue

22. Alkylphenols
Increasing sensitivity of analytical methods and negative perception
Alkylphenols are not readily biodegradable
EU is particularly sensitive to these issues

23. Increased Focus on Purity and Tougher Hygienic Requirements in EU
New tests methods with ppb detection limits have been developed that ensure “unsuspected substances” do not migrate into drinking water intended for human consumption (EN 15768)
May include intermediates, additives and additive byproducts.

25. New Liquid Green Phosphite (LGP-11)
New technology, patent pending
Contains no alkylphenols
Composed of non-toxic biodegradable raw materials
High MW, low migration/low exposure
Excellent process stability (5% phosphorus), compatibility, hydrolytic stability, long term aging and resistance to gas fade

26. No Alkylphenols
New technology has been developed that preserves the thermal and hydrolytic stability of phosphites that previously was only obtained through the use of alkylphenols

27. Thermal Stability TGA Weight Loss

28. Hydrolytic Stability % Phosphite Remaining
Neat Phosphites Exposed to 50°C, 85% Humidity
All Phosphites Contain 1% TIPA
% Phosphite
Remaining

29. Performance Evaluation
Performance measured with multiple pass extrusion in LLDPE, MI and YI retention
Co-rotating twin screw extruder
Compounding: °C
Multi-pass: °C
Phosphites levels indicated, formulations also contained 500ppm AO-1

30. Melt Flow Index - LLDPE 2.16kg/190°C

31. Melt Flow Index - LLDPE 21.6kg/190°C

32. Yellowness Index - LLDPE

33. Gel Counts – LLDPE Cast Film Extrusion

34. Gas Fade Resistance in LLDPE at 60°C

35. Compatibility at 2000ppm in LLDPE
Gloss
Solid phosphite SP1 is not compatible at 1500ppm
Days in Oven at 60°C

36. Migration From The Polymer
Assuming Fickian diffusion, migration rates decrease with an increase in molecular weight
Molecular weight of LGP11 is >> TNPP
Decreased exposure from consumer packaging, especially in food contact applications

37. Conclusions
LGP-11 is a high MW liquid phosphite that offers better performance than typical commodity phosphites such as TNPP and SP1
Process stability (MI/YI), compatibility, NOx and oven aging, thermal stability
LGP-11 is alkylphenol free and is based on nontoxic biodegradable raw materials, and thus avoids many of the negative perception issues associated with phenolic based antioxidants.

38. Questions?