Dr. Mick Jakupca Jake Lance Dover Chemical Corporation Investigating the use of polymeric phosphites to improve processing, melt fracture and thermal stability Dr. Mick Jakupca Jake Lance Dover Chemical Corporation 2019 SPE Polyolefins Conference Houston, Texas

Presentation Outline Introduction to non-alkylphenol based polymeric phosphite stabilizers (Doverphos LGP-11) LGP-11 performance data displaying the typical functions of a phosphite LGP-11 ancillary benefits that are not typical of commodity phosphites And…an unexpected benefit…how to use polymeric phosphites as melt fracture synergists

Phosphite Stabilizers What it is a phosphite supposed to do? Protect the polymer from degrading during melt processing Get “out of the way” when it is done Do not negatively affect other properties such as color, NOx gas fade, gamma irradiation, compatibility, plate-out and bloom, migration and exposure, etc.

Polyolefin Stabilizers Most polyolefin stabilizer packages include a primary antioxidant (such as a hindered phenolic) and a secondary antioxidant (usually a phosphite). This is what phosphites are “supposed to do”.

What They Are “Not” Supposed To Do… Do not add significant color either during processing or heat aging Do not plate-out on equipment during processing, especially in LLDPE cast film application Do not bloom to the surface of the polymer post-processing Do not hydrolyze (can cause bad specs and poor stability) Do not negatively interact with other additives such as PPAs, UV stabilizers, etc. Do not significantly migrate from polymers to food (migration is proportional to molecular weight)

What They Are “Not” Supposed To Do… Do not contain components that are present on various regulatory lists such as Prop 65, nor are considered Substances of Very High Concern (SVHCs). Do not contain components that are present on non-regulatory NGO “hit lists” Often emotional issues, not safety, but just as important if you want to sell your product and “keep it alive” for the long term. Preferably do not contain alkylphenols which are often present on both types of lists. Do not result in Non-Intentionally Added Substances (NIAS) during processing or post processing (now a major focus….even at ppm levels).

Doverphos LGP-11 – Polymeric Phosphite Doverphos LGP-11 is a polymeric phosphite that was designed to be “Green”. Very low migration/exposure, good performance and composed of materials that are not based on alkylphenols or other components “under the spotlight” Most of the commonly used melt process stabilizers are based on alkylphenols TNPP SP-1 DN76

What Phosphites Are “Supposed To Do” Phosphites are used with primary antioxidants to protect the polymer during melt processing Multiple pass extrusion tests are a common method of measuring melt stability of the polymer (melt index and color) LLDPE Resin (Metallocene) 800ppm of phosphites (LGP-11 vs. SP-1) 500ppm of primary AO-1 Co-rotating twin screw extruder Compounding: 170-175-180-190°C Multi-pass: 180-205-225-245°C

Melt Index (MI) (2.16kg/190°C) LGP-11 and SP-1 Have Similar Performance And Similar % Phosphorus

Yellowness Index (YI) LGP-11 has MUCH better color control than SP-1 (It is a fast phosphite, alkyl versus alkylphenol)

Expectations LGP-11 does what it is supposed to do during melt processing Good MI performance compared to SP-1 (and TNPP) Excellent YI control compared to commodity phosphites What happens after melt processing? Does it do anything it is not supposed to do? (The advantages of LGP11 have been covered in previous presentations) Compatibility and bloom/exudation Gamma Irradiation Migration and exposure Etc. BUT…..what else is there? This paper will focus on unique processing benefits offer by polymeric phosphites

Plate-Out/Bloom Phosphites can contribute to plate-out and bloom issues causing buildup on production equipment and powder/haze on surface post production. White film on surface indicates additive is blooming Film is clear

Compatibility-Bloom Test Compound LLDPE formulation in Brabender-Bowl (torque rheometer) followed by compression molding and quench cooling. This results in highly amorphous LLDPE. Aging the compression molded plaques at 60°C accentuates any potential of the additives to bloom. Bloom can be monitored by measuring the surface gloss. Surface gloss is reduced if an additive blooms. The composition of the bloom can be identified by surface ATR-FTIR and other analytical techniques

Bloom Measurement Phosphites loaded at 2000ppm LGP-11 vs SP-1 vs TNPP The solid phosphite SP-1 is known to have compatibility issues when used in cast film applications at levels >1000ppm. It can plate-out on equipment during processing, leading to shut-downs and cleaning. It can cause surface bloom/powder to form after processing. TNPP is generally preferred over SP-1 in cast film applications because of its good compatibility

Compatibility @ 2000ppm in LLDPE Solid phosphite SP-1 is not compatible at 1500ppm

LGP-11 Can Be Used to “Help Out” SP-1 Blend of LGP-11 and SP-1 Solid phosphite SP-1 is not compatible at 1500ppm

Improved NOx – Gas Fading Performance Hindered phenolic antioxidants are a major contributor to color increase during NOx exposure and heat aging. High loading levels and over-oxidation of the phenolic AO cause increased discoloration. LGP11 is a “Quick” phosphite. Kinetic studies have shown that it quickly scavenges hydroperoxides, and thus doesn’t make the primary AO work “as hard”. (Helps prevent formation of color causing quinone species).

Another Option – LGP11 and Vitamin E Vitamin E is a “fast” primary AO, it is a carbon radical scavenger. Its main drawback is higher color. LGP11 is a “fast” phosphite, and eliminates the color issue associated with Vitamin E when used as a blend. A “fast” phosphite plus a “fast” primary antioxidant. Blends of LGP11 and Vitamin E can significantly reduce or eliminate NOx gas fade color issues Replacement or reduction of hindered phenolic AO with much lower loading levels of Vitamin E LGP11 improves initial color, protects the Vitamin E from over-oxidation and results in little color increase upon aging

Improved Gas Fading Performance Comparison between TNPP/DN76 versus LGP11/DN76 and LGP11/Vitamin E 1500ppm TNPP and 500ppm DN76 1500ppm LGP11 and 500ppm DN76 1500ppm LGP11 and 100ppm Vitamin E LLDPE Formulations extruded three passes at 250°C Samples of the 3rd pass were compression molded into 20mil thick plaques and aged in a NOx chamber at 50°C Yellowness Index (YI) was measured during the exposure

Gas Fading/NOx Performance

Migration- Food Packaging In food packaging applications, additives will migrate from the polymer into the food. The amount of migration is related to the moleculare weight of the additive. NIAS (Non Intentionally Added Substance) is currently a major concern. Attention is being focused not only on the additives themselves, but also their oxidation and hydrolysis products. LGP-11 is polymeric which limits migration. It is also well known that chemicals with a molecular weight great than 1,000 are not readily bioavailable, and thus less of a toxicity concern.

Migration - Fickian Diffusion At a given time/temperature/concentration, migration is related to the diffusion coefficient, which is dependent upon Molecular Weight Mt = 2Cpo(Dpt/π)1/2 * Mt = Migration at time t Cpo = Concentration in the polymer Dp = Polymer diffusion coefficient Dp = 104 exp(Ap–aMw– bT-1) ** Dp is the diffusion coefficient of additive/migrant Mw is the molecular weight of the additive, Diffusion will exponentially reduce as MW goes up T is temperature (K) a and b are constants (0.01 and 10450 respectively) Ap depends on the polymer and temperature Molecular Weight * Crank, J., “The Mathematics of Diffusion”, 2nd ed., Oxford University Press, London, 175 ** A.Baner, J.Brandisch, R.Franz, O.G. Piringer, Food Additives and Contaminants, 1996, 13(5), 587-601

FDA-Type Migration Study of Additives Into Food Selected additives were compounded into LLDPE using a Brabender torque rheometer at a concentration of 1000ppm. Formulations were then compression molded into plaques. Plaques were exposed to 95% ethanol at 70°C for 2 hours. 95% ethanol is considered a fatty food simulant. Solutions were then analyzed for additive content. Additive migration was measured as µg of additive that migrated per inch squared surface. ppm in Food µg (additive) in2 surface Assume 10g food/in2 (µg (additive)/10) grams food

Migration of Additives - Fatty Food Simulant MW (g/mole) Ppm in Food DTBP 206 15.2 SP-1 646 5.2 TNPP 688 5.9 SP-2 852 2.2 LGP-11 >1500 <0.5

Migration and Molecular Weight Amount of migration decreases with MW At a set time and temperature, relationship is not linear Migration exponentially decreases with an increase in MW Dp ~ Constant * exp(-0.01*Mw) Migration = Constant * CPO * (Dp)1/2 Migration is significantly Reduced when MW of Additive is above ~1,200

So…The Unexpected Property… LGP-11 does what is supposed to do. It “looks good”. LGP-11 doesn’t do anything “bad” after melt processing. There are a lot of “bad” things that must be avoided. LGP-11 is also “unique”. The unexpected property is that LGP-11 can be used to improve melt processing and reduce melt fracture.

Melt Fracture Under certain conditions, blown film processing of LLDPE may result in melt fracture. This surface irregularity or roughness negatively affects the properties of the polymer. Melt fracture is dependent upon many variables including resin type, additive formulation, melt temperature, output rates, equipment design, etc. Polymeric Process Aids (PPA) are commonly used to reduce or eliminate melt fracture LLDPE (no PPA) LLDPE w/PPA Source: Paul Neumann, Dyneon/3M, PLACE Conference, 2007

Melt Fracture - PPAs Polymeric Process Aids (PPA) are generally composed of fluoropolymers, which are often combined with other additives such as interfacial agents, minerals or other polymers. They are used at levels from ~300ppm to 1000ppm. PPAs have a high affinity for metal surfaces, and form a fluoropolymer layer on the extruder die, which allows the melt to easily slip through. The use of PPAs improve melt processing. Benefits include increased throughput, lower operating pressures, reduced gel formation, ability to run equipment at lower temperatures or reduced film thickness, reduced die buildup, etc.

Melt Fracture - PPAs As the PPA coats the extruder die over time, melt fracture is gradually decreased. The time it takes to fully remove melt fracture is called “Time To Clear”. Source: Steve Oriani, DuPont, SPE Polyolefins Conference, 2010

Interfacial Agents - PPAs Interfacial agents are commonly used with fluoropolymer PPAs, although they do not prevent melt fracture by themselves. They improve the coating process of the PPA and increase their general effectiveness. They are “synergistic” in that a blend of a an interfacial agent and a fluoropolymer is often more effective than the fluoropolymer by itself. Interfacial agents are often low molecular weight polar polymers such as Polyethylene Glycol (PEG) and Polycaprolactone (PCL)

Melt Fracture Effects Various factors influence the onset of melt fracture such as temperature, throughput rates, resin type, die geometry and additive interactions. Interfacial additives improve PPA performance Other additives can negatively affect PPA performance

Negative Interactions Various additives negatively interact with PPAs Antiblocks such as amorphous silica and talc Fillers such as calcium carbonate Hydrotalcites Highly basic HALS UV stabilizers Carbon black TiO2

Phosphites and Melt Fracture Most commonly used Phosphite stabilizers are either monophosphites or diphosphites. Phosphite stabilizers could be considered “bystanders” when examining their structure-activity effects on melt fracture. Phosphites are generally not considered good nor bad when comparing different commercial products. However, if not used properly, degradation of the polymer can occur which negatively affects melt fracture.

Advantage of a Polymeric Phosphite Unlike commodity phosphites, the polymeric nature and backbone structure of LGP-11 lends itself to beneficial properties that are similar to interfacial polymeric agents. LGP-11 itself does not act as a PPA, but rather improves melt fracture performance when used in conjunction with a PPA The replacement of TNPP or other phosphites with LGP-11 improves melt fracture, even without switching the level or type of PPA, or changing the PPA interfacial agent.

LGP-11 Melt Fracture and Processing Benefits LGP11 can be used to replace TNPP and other solid phosphites. This has several potential melt fracture and processing benefits: Reduced time to clear melt fracture (quicker start-up) Potential to decrease the PPA level (cost savings) Ability to run equipment at higher throughput rates (lbs/hour) without observing melt fracture Ability to operate the extruder at lower temperatures without observing melt fracture (less degradation, lower energy cost) Potential to replace PEG (polyethylene glycol) interfacial agent. PEG reduces melt stability because of degradation.

Improvements in Melt Fracture Polymer evaluations were run on a counter-rotating twin screw Brabender extruder with a flex lip die attachment. A film/tape of 20mil was produced. Variables studies include temperature, PPA levels and RPMs (throughput).

Improvements in Melt Fracture – Time to Clear Extruder was operated at conditions that initially produced 100% melt fracture. 0.8MI ZN LLDPE Melt Temperature = 230°C Shear Rate = 320 s-1 300ppm Primary AO 650ppm PPA (Fluoropolymer only, no PEG or other interfacial agents) Via Direct Compounding Phosphites were compared 1800ppm LGP-11 1800ppm TNPP

Improvements in Time to Clear Melt Fracture (Optical Microscope Picture of Film Surface) TNPP (Initial) (30 Minutes) (60 Minutes) LGP11 (Initial) (30 Minutes) (60 Minutes) Flow Path

Time To Clear Melt Fracture Reduction of PPA Level TNPP did not completely clear melt fracture under these lab conditions. LGP11 cleared within 60 minutes. The level of PPA was reduced from 650ppm to 350ppm and the Time to Clear melt fracture was measured. LGP-11 clears melt fracture significantly quicker than TNPP (time saving) and also allows a reduction in PPA level and potential cost savings Phosphite PPA Level Time To Clear Melt Fracture TNPP 650 Did not clear melt fracture LGP-11 Within 60 Minutes 350

Increased Extruder Output Rate After the melt fracture was cleared (at 60 minutes) the output rate of the extruder was increased to determine the onset of melt fracture with respect to shear rate. LGP-11 allows increased output without melt fracture under these lab conditions. A simple change from TNPP to LGP11 as the stabilizer could potentially increase equipment capacity, if melt fracture at the extruder-die is the limiting rate factor (not including bubble cooling and other variables) Phosphite PPA Level Shear Rate* Melt Fracture (after 60min) Output Rate TNPP 650 237 s-1 100% Melt Fracture 4.6lbs/hour LGP-11 No Melt Fracture 362 s-1 7.1lbs/hour 419 s-1 No Melt Fracture 8.2lbs/hour 473 s-1 Slight Melt Fracture 9.3lbs/hour TNPP resulted in melt fracture at 4.6lbs/hour LGP11 showed no melt fracture at 8.2 lbs/hour, >75% increase in output rate compared to TNPP

Reduced Extrusion Temperature Extruder was operated at conditions that initially produced 100% melt fracture. 0.8MI ZN LLDPE 300ppm Primary AO 600ppm PPA (Fluoroelastomer/PEG blend) Via letdown of PPA masterbatch Phosphites were compared 1800ppm LGP-11 1800ppm TNPP Melt Temperatures compared at 230°C and 210°C Lower processing temperatures less thermal degradation/gels, lower energy consumption, potential improved cooling

Temperature Reduction At time = 0, all formulations had 100% melt fracture TNPP (After 60 minutes @ 230°C, Shear Rate = 473s-1) Partial Melt Fracture LGP-11 (After 60 minutes @ 230°C, Shear Rate = 473s-1) No Melt Fracture * Corrected Shear Rates

Temperature Reduction Melt Temperature reduced from 230° to 210°C TNPP (After 60 minutes @ 210°C, Shear Rate = 473s-1) Partial Melt Fracture LGP-11 (After 60 minutes @ 210°C, Shear Rate = 473s-1) No Melt Fracture * Corrected Shear Rates

Reduced Temperatures AND Increased Output Rates Shear Rate Increased after 60 Minute Conditioning at 210°C LGP-11 (After 60 minutes @ 210°C, Shear Rate = 473s-1) No Melt Fracture LGP-11 (After 60 minutes @ 210°C, Shear Rate = 642s-1) No Melt Fracture

Theory : LGP-11 Acts as an Interfacial Agent One explanation of improved properties: LGP-11 acts as an interfacial agent, due to its polymeric nature. If so…LGP-11 should show improved melt fracture without the interfacial agent present. Goal: compare melt fracture performance of SP-1 vs LGP-11 using PPAs with and without an interfacial agent PPA1 (fluoroelastomer/PEG blend, PEG is the interfacial agent) PPA2 (only fluoroelastomer, no PEG or other interfacial agent)

Theory : LGP11 Acts as an Interfacial Agent Most of the commonly used PPAs contain either PEG or PCL along with the fluoroelastomer The blend is synergistic, usually offering better performance than the fluoroelastomer by itself Example PPA1: 25-35% Fluoroelastomer 60-70% PEG 5% “others” such as calcium carbonate or talc Example PPA2: Only Fluoroelastomer No PEG/PCL

Extrusion Conditions 1MI LLDPE Metallocene Resin Brabender ¾” Single Screw Extruder (1:25 L/D) Melt Temp 200°C, shear rate of ~440 s-1 Ribbon die (2” width, 20mil thickness) with pressure probe attachment Phosphites compared 1500ppm LGP-11 1500ppm SP-1 Both formulations contained 500ppm of a primary antioxidant

PPA With and Without Interfacial Agent PPA formulation levels PPA 1 used at 600ppm, equivalent to: ~ 180ppm Fluoroelastomer ~ 400ppm PEG PPA 2 used at 180ppm 180ppm Fluoroelastomer No PEG Thus, the formulations contain ~ the same level of fluoroelastomer, the only difference is one contains PEG, the other does not.

PPA1 - Time To Clear Melt Fracture LGP-11 with 600ppm PPA1 (Fluoroelastomer + PEG) SP-1 with 600ppm PPA1 (Fluoroelastomer + PEG) Both formulations adequately cleared melt fracture under these conditions using PPA1. LGP-11 cleared melt fracture quicker than SP-1. LGP-11 formulation: cleared melt fracture in ~ 15 minutes SP-1 formulation: cleared melt facture in ~ 30 minutes

PPA2 - Time To Clear Melt Fracture LGP-11 with 180ppm PPA2 (Only Fluoroelastomer, No PEG) SP-1 with 180ppm PPA2 (Only Fluoroelastomer, No PEG) LGP11 formulation: cleared melt fracture in ~ 20 minutes SP-1 formulation: did NOT completely clear melt fracture after 60 minutes

LGP-11 SP-1 10min 20min 30 min 10min 20min 30 min 60min

LGP-11 Pressure Reduction

LGP11 : Interfacial Agent/Synergist SP-1 and LGP-11 cleared melt fracture with PPA1 SP-1 did not clear melt fracture with PPA2 (no PEG) SP-1 “needed” the PEG interfacial agent LGP-11 cleared melt fracture with or without PEG LGP-11 did not “need” the PEG interfacial agent LGP-11 resulted in lower pressure throughout the extrusion Conclusion: It is likely that LGP-11, a polymeric phosphite, is acting similar to an interfacial agent

Dynamic Aspect – Thick Profile Die Gap - 0.25 inches, Width – 1 inch Extruder equilibrated for 30 minutes with SP-1/PPA2 formulated resin At 30 minutes, the feed was switched to LGP-11/PPA2 formulated resin

Conclusions LGP-11 provides good MI performance and excellent color performance versus other phosphites. The “easy” part. LGP-11 doesn’t do anything “bad” after melt processing. It offers improved ancillary properties versus other phosphites such as improved compatibility, NOx-Gas Fade, low migration, etc. The “unexpected” property is that LGP-11 is effective at reducing melt fracture, reducing pressure and improved overall processing. Now, what next? Story to be continued…

Thank You!