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

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

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

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

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)

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 178.2010, 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

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

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

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

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)2 + 2 H2O H3PO3 + 2 ROH Acidic =“ Black Specks”

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

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

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

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

Phosphite Activity (Depends on Polymer) Peroxide decomposition P(OR)3 + R’OOH O=P(OR)3 + 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 + ZnCl2 Zn[OP(OR)2]2 + 2RCl 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

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

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

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

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

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

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

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

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.

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

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

Thermal Stability TGA Weight Loss

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

Performance Evaluation Performance measured with multiple pass extrusion in LLDPE, MI and YI retention Co-rotating twin screw extruder Compounding: 170-175-180-190°C Multi-pass: 180-205-225-245°C Phosphites levels indicated, formulations also contained 500ppm AO-1

Melt Flow Index - LLDPE 2.16kg/190°C

Melt Flow Index - LLDPE 21.6kg/190°C

Yellowness Index - LLDPE

Gel Counts – LLDPE Cast Film Extrusion

Gas Fade Resistance in LLDPE at 60°C

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

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

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.

Questions?