Lube-Tech PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
4a & 4b and 5a & 5b, plant retained samples give essentially identical spectra when aged 12 or 18 month. This demonstrates the high stability of borate condensate additives when stored under typical conditions, regardless of the additive composition. This analysis of the aged samples clearly indicates that the condensation process is complete and prevents the possibility of reverse hydrolysis and release of boric acid on storage. Visually the aged and fresh samples are indistinguishable, with no change in colour and no signs of precipi- tation or splitting.
Fig 5a April 2011
Throughout this program, there has been considerable debate regarding the analysis and the implications. Afton Chemical has undoubtedly developed a far deeper knowledge of the borate condensate additives, their chemistry and manufacturing processes. Information such as long term stability and hydrolytic stability is clearly of significant value and it is reassuring to see stable long life products. Developing an analytical method capable of reliably detecting boric acid at very low levels and further demonstrating the lack of measurable boric acid in the condensate additives is a real technical achievement.
Fig 4b April 2012
We have been able to determine that the additives manufactured do not contain boric acid. However, this is not the end of the investigation. Most metalworking formulations that use borates have a moderately high pH around 9.0 – 10.0 and under these conditions, the working fluid is stable and offers optimum corrosion protection for most metal. These are also optimum conditions to maintain the stability of the borates. Afton continues to investigate the use of borates to develop a more compre- hensive picture of the stability over time and under different metalworking conditions.
Fig 5b March 2012 Conclusion
Figures 4a, 4b, 5a & 5b In all, eighteen samples were analysed during this final stage and again no evidence of free boric acid was seen at the 0 ppm chemical shift. In each case the sample is indicated in green, boric acid at 0.2% in red and boric acid at 0.1% in blue. As can be seen in figures
24 LUBE MAGAZINE No.110 AUGUST 2012
Afton has developed a NMR method capable of identifying free boric acid down to very low levels. The limit of detectability for free boric acid is below 0.02%. A selection of boric acid condensation products were analysed and the analysis confirmed that these products do not contain a detectable level of free boric acid.
During the course of this investigation over 50 individual borate condensate samples have been analysed. These include samples used in the method development phase, lab prepared borate condensates, plant manufactured borate condensates, typical formulations using a range of borate condensates and plant samples aged up to 18 months. Great care has been taken to ensure the analysis of each sample and product was consistent and of a high standard.
We conclude that Afton Chemical’s fully reacted Borate condensation products are free from detectable levels of boric acid (where the limit of detectability is 0.02% free boric acid).
Based on this work, and the evidence from formulated fluids, Afton Chemical is confident that these fully reacted borate corrosion inhibitors, manufactured to the process described used in aqueous MWF under normal metalworking conditions and pH do not contain detectable levels of free boric acid. The supply and use of these additives and fluids incorporating them are therefore not required to carry labelling or notification regarding the presence of boric acid.
Steven Anderson
Afton Chemical Metalworking Fluids Group Technology Manager, R&D Manchester, United Kingdom
LINK
www.aftonchemical.com
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