The Lubrizol Corporation
Market Demands New Approach to RP Fluids

By Derek Phillips, Commercial Manager – Metal Protection | TLT CMF Plus November 2010

At the end of the day, manufacturers who work with metals want one thing from rust preventive (RP) technologies: the assurance that their metal products will arrive at their destinations free of rust or stain. But environmental concerns and competitive pressures have complicated that challenge for blenders and formulators in recent years with additional, more complex requirements. Today’s RPs are frequently expected to:

• Be compliant with the divergent standards and availability requirements of a global market
• Be compatible with a wide range of metal substrates
• Eliminate workplace and disposal hazards associated with heavy metal exposure
• Reduce the processing time associated with cleaning protective films
• Deliver competitive advantage by providing exceptional resistance to salt spray and other corrosive challenges
• Remain stable at cold temperatures without crystallizing or separating

This article will explore these challenges and the next generation RP technologies designed to meet them.

Market Challenges
Whether manufacturing small components such as nuts and bolts; component assemblies such as brake systems, engines, compressors, and ancillary parts; or metal for household appliances such as small pumps and motors – metals at every stage of manufacture and fabrication require protection to prevent corrosion of exposed surfaces prior to application of their final coating or finish. A few of the challenges faced in the market today:

• The wide ranges of metal substrates in use globally, each requiring specialized protection during manufacture or fabrication.

• The move away from heavy metals in many regions of the world due to environmental concerns, which makes traditional barium-based chemistries unacceptable to many manufacturers.

• The increasing distances between the site of component manufacture and the point of assembly, resulting in long-distance shipping and the need for greater salt spray resistance.

• The conflict between the need for exceptional salt spray performance, traditionally achieved through thicker films, and competitive pressures to reduce cleaning times.

• The ever-widening array of base oil and solvent diluent requirements to serve a global market.

• Environmental concerns related to the use of volatile organic compounds (VOCs).

• Solubility concerns related to reducing VOC aromatics

An Alternative Approach
Traditional RP formulations combine sulfonates or oxidates with wax petroleum byproducts. These have proven intractable when it comes to achieving extreme salt spray performance while maintaining near invisible film thinness with a clear/stable finished product. To achieve the one, you must sacrifice the other. After a highly focused research effort, Lubrizol devised a new chemical approach through which blenders and formulators can achieve salt spray resistance up to and greater than 100 hours, as measured by ASTM B117, in a thin film rust preventive. Available in both barium-based and calcium-based chemistries, these additive packages can be applied at varying treatment rates to achieve a wide range of performance levels. They are compatible with an extensive range of oil and solvent diluents and a variety of metals, allowing finished fluid blenders and formulators to reduce their inventory requirements while extending the performance profiles of their Rps. (See Figure 1).


Figure 1.
(1) Solvent is 140˚F (60˚C) Flash Point Solvent
(2) Oil is 100 Sec Naphthenic

Eliminating Hazards
There are two types of environmental hazards associated with traditional RP chemistries:

• Those related to the use and disposal of heavy metals
• Those related to the use of high aromatic VOCs

In relation to the first point, these new calcium-based chemistries achieve salt spray performance up to and greater than 100 hours. This is comparable to the barium-based version and far exceeds competitive solutions, with a clear, stable product. This enables blenders and formulators of high-performance RP fluids to significantly increase the value delivered to their customers, without barium chemistries.

In relation to the second point, since both chemistries are compatible with environmentally responsible low-VOC diluents, those seeking to minimize such hazards may do so, confident of solubility performance that will ensure consistent RP quality.

Reducing Processing Time
With the new RP technology, the final products achieve excellent water separation for complete dip tank drain-off, resulting in cleaner metals and more consistent application in less time. (See Figure 2)


Figure 2.
Pictures taken: 2:30 (min:sec)
15% Additive in 100˚F (40˚C)
Flash Point Solvent

Delivering Competitive Advantage
The ability to ensure customers of exceptional corrosion protection and stain resistance using a thin film RP is a compelling advantage in today’s competitive global arena. This new chemical approach offers two additional benefits that can improve profitability:

• The ability to deliver multiple performance levels, reducing the number of additives for formulating
• Compatibility across a wide range of diluents and metals

Performing at Cold Temperatures
It’s long been understood that removing the aromatics from diluents makes it more difficult for fluids to maintain their solubility. Cold temperatures can cause the waxy oxidates to crystallize out of the fluid, separating to the bottom, resulting in inconsistent protection of treated metals. Fluids formulated using next generation alternative RP technologies remain fluid at lower temperatures.

Typically, finished fluids formulated using this advanced RP technology demonstrate excellent solubility: 

When blended with solvents:
fluid at temperatures as low as -10°C 

When blended with oils: 
fluid at temperatures as low as 0°C 

After extended storage:
excellent recovery at temperatures as low as -20°C

Conclusion
Steel manufacturers, metal fabricators, and parts manufacturers typically coat metal coils, sheets, and components with a rust inhibiting film to prevent exposed surfaces from rusting during shipment and storage. In addition, when metal components are being machined, they may need to be coated multiple times to prevent exposed surfaces from rusting between processes. Traditional rust preventives have failed to keep pace with increasing performance demands, particularly in the areas of salt spray protection, cold temperature stability, and related issues of solubility.

The newest chemical approach to RP technology enables metalworking fluid blenders and formulators to achieve exceptional salt spray and cold temperature protection while imparting only a thin film on the treated metals, thereby reducing the time and costs associated with cleaning metals prior to painting. By varying treatment rates, formulators can now customize thin film rust preventive solutions using solvent, solvent/oil, or oil diluents – thereby achieving optimum versatility with minimum inventory.

To find out more go to http://www.lubrizol.com/ALOX/