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www.crodalubricants.comwww.crodalubricants.com
Improving SealConditioning
without Phthalates
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Content
• Impact of lubricant base stocks on elastomeric seals
• Market trends- base stock supply
• Common seal conditioning additives
• New seal swell ester for lubricants
• Questions from the audience
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Impact of Base Oil and Additives on Seals• Base oils and additives can leach out plasticizers and other
additives from seals, negatively impacting its performance
• The less polar the base oil, the more aggressive it is to seals
• Effects of base oils on seals:
Group IV(PAO) > Group III > Group II > Group I
• Sulfurized olefins attack residual unsaturation in the elastomers.
• Amines and highly basic dispersants harden the seals and make them brittle
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Effect of PAO on Seals
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Base Stock Composition
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Group III- Global Capacity
• Capacity Increase of 48% starting in late 2011• Neste-Bapco- Bahrain 7,700 b/d• Shell- Qatar (GTL) 28,800 b/d
• Gas-to-Liquid base stocks• Group III base stocks• Shell’s current capacity- 1,150 b/d
2011 2012 % Increase
Group III Capacity (b/d)* 60,030 89,980 48%* Lubes and Greases 2011 Non‐conventional base stocks guide
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Growth in Seal Swell Additive Requirements
• GTL base stocks will have a similar effect on seals as PAO
• Demand for seal conditioning additives will increase significantly
2011 2012 % IncreasePAO Capacity (metric T/y)* 506,300 506,300Gas‐To Liquid Capacity (metric T/y)* 1,681,920Total PAO/GTL 506,300 2,188,220 332%* Lubes and Greases 2011 Non‐conventional base stocks guide
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Common Seal Swell Additives and Solubilizers• Phosphites and Phosphates
• Can be too aggressive towards seals• Environmental and toxicity concerns• Can Interfere with anti-wear and EP agents• Total phosphorus level limitations
• Heterocyclic nitrogen and sulfur containing agents• Surface active, may interfere with anti-wear and EP agents, friction
modifiers, and yellow metal corrosion inhibitors
• Esters• Improved solubility and sludge dispersancy• Minimal interference with EP agents, friction modifiers, yellow metal
corrosion inhibitors
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Esters as Seal Swell Agents
• Phthalates• Petroleum based, non renewable• Environmental concerns. Can lead to birth defects
• Diesters • Petroleum or bio-based, renewable content varies• Biodegradability from good to poor depending on structure
• Polyol esters• Petroleum or bio-based, renewable content varies• Biodegradability from good to poor depending on structure
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Factors Affecting Seal Swell Activity
• Type of elastomers• Hydrogenated nitrile rubber• Polyacrylate rubber• Fluoroelastomers• Silicone rubbers
• Concentration of a seal swell additive• 0.5 – 10% mass percent
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Factors Affecting Seal Swell Activity
• Chemical family• Phosphites and phosphates • Heterocyclic amines• Esters
• Molecular structure and weight• Type of ester- e.g. phthalate, diester, monoester etc.• Linear vs. branched alkyl chains• Molecular weight
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Seal Swell Effects By Chemical Family
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Seal Swell Activity- Hydrogenated Nitrile Rubber (HNBR-1)
Increase of molecular weight leads to decrease of activity for all elastomers except silicone rubber (VMQ-1). Phthalates provide more seal swell activity compared to other types of esters
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Phthalate Environmental Concerns
• Phthalates are banned for use in children’s toys in the U.S. and the E.U.
• EPA lists phthalates as a “chemical of concern.” Committee was created in 2006 by congress to monitor BPA and phthalates
• In January 2010, Australia banned consumer products containing more than one percent Bis(2-Ethylhexyl) phthalate (DEHP/DOP)
• Environmental fate of more than half of lubricants volume worldwide is unaccounted for. There are concerns over aquatic toxicity and the effects of chronic exposure to phthalates
• United States Consumer Product Safety Commission provides page with reviews and toxicity data:http://www.cpsc.gov/volstd/phthalates/phthalates.html
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Seal Swell Activity- Hydrogenated Nitrile Rubber (HNBR-1)
Bio-based esters perform similar to phthalates at comparable molecular weights.
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New Bio-Based Ester for Seal Swell
• Perfad 5000 provides equal or better seal swell performance to phthalates
• Not aquatically toxic • Daphnia Acute Toxicity > 100mg/l (OECD 202)
• Made from 100% bio-based raw materials, derived from plants and animal sources
• 100% Biodegradable (OECD 301B)
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Test Method
• Modified ASTM D7216- standard test method for determining automotive engine oil compatibility with typical seal elastomers
• Weight change and volume change were measured before and after the test
• Standard set of elastomers tested.• Hydrogenated Nitrile Rubber (HNBR-1) 355 hours at 100ºC• Fluoroelastomer (Viton, FKM-1) 355 hours at 150ºC• Polyacrylate rubber (AMC-1) 355 hours at 150ºC• Silicone rubber (VMQ-1) 355 hours at 150ºC
• All experiments ran in triplicates
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Weight Change vs. Volume Change
R2 = 0.9858
-6
-4
-2
0
2
4
6
8
10
-6 -4 -2 0 2 4 6 8 10Weight Change, %
Volume Change, %
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Nitrile Rubber (HNBR-1)
Concentration vs. Weight Change, Hydrogenated Nitrile Rubber (HNBR-1), Ester in PAO 4.
-5-4-3-2-1012345
0 2 4 6 8 10
Concentration (Mass %)
Weight Change
(%)
Perfad 5000C6-PhthalateC8-PhthalateC12-PhthalatePAO 4
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Nitrile Rubber (HNBR-1)
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Polyacrylate Rubber (ACM-1)
Concentration vs. Weight Change- Polyacrylate Resin (ACM-1), PAO4 + Ester
-4-3-2-10123456
0 2 4 6 8 10
Concentration (Mass %)
WeightChange
(%)
Perfad 5000C6-PhthalateC8-PhthalateC12-PhthalatePAO 4
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Fluoroelastomer Rubber (Viton FKM-1)
Concentration vs. Weight Change- Fluoroelastomer (Viton, FKM-1), PAO 4 and Ester
-1
0
1
2
3
4
5
6
7
0 2 4 6 8 10 12
Concentration (Mass %)
Weight Change
(%)
Perfad 5000C6-PhthalateC8-PhthalateC12-PhthalatePAO 4
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Silicone Rubber (VMQ-1)
Concentration vs. Weight Change- Silicone Rubber (VMQ-1), PAO4 + Ester
-10
-5
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12
Concentration (Mass %)
WeightChange
(%)
Perfad 5000C6-PhthalateC8-PhthalateC12-PhthalatePAO 4
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Concentration and Molecular Weight
• Increase in molecular weight leads to significant decrease in seal-swell activity
• In nitrile rubber, Viton and polyacrylate elastomers, weight change is proportional to concentration
• Perfad 5000 is equal to phthalates in reversing seal shrinkage of hydrogenated nitrile rubber elastomers, more effective for fluoro- and polyacrylate elastomers
• Perfad 5000 more effective than diesters and monoesters
• Silicone rubber results were inconsistent
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Perfad 5000- Physical Properties
Property Test Method Perfad 5000 C6-Phthalate C8-Phthalate C12-Phthalate
KV 40, cSt @ 40°C ASTM D 445 26.9 15.0 24.2 49.3
KV 100, cSt @ 100°C ASTM D 445 5.9 3.4 4.2 6.2
Viscosity Index ASTM D2270 173 98 74 68
Flash Point, ºC ASTM D 92 244 192 218 245
Pour Point, ºC ASTM D 97 -8.3 -27 -25 -21
NOACK Volatility D5800-08 8.6
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Summary
• Seal swelling power of Perfad 5000 is equal or better to phthalates for a comparable molecular weight and treat rate
• Perfad 5000 is equal to similar molecular weight phthalate esters in reversing shrinkage of seals made of hydrogenated nitrile rubber elastomers
• Perfad 5000 is more effective than phthalates for swelling fluoro-and polyacrylate materials
• Perfad 5000 and phthalates were significantly more active than di-esters and monoesters of similar molecular weight
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APPENDIX
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TGA of Mineral Oil
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TGA of Developmental Ester 2
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The information in this publication is believed to be accurate and is given in good faith but no representation or warranty as to its completeness or accuracy is made.
Suggestions for uses or applications are only opinions. Users are responsible for determining the suitability of these products for their own particular purpose.
No representation or warranty, express or implied, is made with respect to information or products including without limitation warranties of merchantability or fitness for a particular purpose or non-infringement of any third party patent or other intellectual property rights including without limit copyright, trademark and designs.
Any trademarks identified herein are trademarks of the Croda group of companies.
Disclaimer
© Copyright Croda Europe Ltd 2011. All Rights Reserved
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