Seatons products for use in lubricants
Vegetable oils can be used in formulations for many types of lubricants including cutting fluids, rolling and metal working oils, drilling muds, two stroke oils, greases, wire drawing and chainsaw lubricants. They may be used as the base oil in formulations (possibly as full or partial replacements for mineral and synthetic oils) or as additives, and can offer the following advantages to formulators:
- Excellent lubricity
- High flash points
- Low toxicity
- Obtained from renewable sources
- High viscosity indices
Suitable oils for use in lubricant applications are non-drying oils such as rapeseed and castor oils, and a summary of suitable grades can be found below.
Crude and refined rapeseed oil
Rapeseed oil has a relatively low iodine value and is therefore not prone to oxidation, making it ideal for use as a lubricant base in either its crude or refined state. Refined rapeseed oil is often favoured due to its low free fatty acid content. Rapeseed oil is available in low, medium and high erucic acid content grades. The low erucic grade is the most readily available and consequently the cheapest. However, in lubricant applications the high erucic grade is often of more interest due to its 40% - 50% erucic acid content, giving the oil a higher degree of lubricity. The high and low erucic acid grades can be blended to give a medium erucic acid grade. Crude and refined low erucic rapeseed oil are used widely in rolling oil formulations for the production of sheet metal.
Oxidised rapeseed oil (blown rapeseed oil)
Rapeseed oil can be oxidatively polymerised (blown) to give a range of products with increased viscosities. The oxidation process also modifies properties such as specific gravity, solubility and reactivity. Oxidised rapeseed oil can be used in lubricant applications where machinery operates at high temperatures, thus the lubricant needs to be a higher viscosity in order to adhere to the surfaces being lubricated. It is also widely used as an additive for drilling muds.
Medium erucic rapeseed oil can also be oxidised under special conditions to give a unique grade, which has excellent mineral oil and solvent compatibility. This is advantageous when the product is added to a mineral oil based lubricant as a thickener, or to give surface-active properties to the blend.
Castor oil – No 1, firsts and Pharmaceutical grades
Castor oil is a non-drying oil with functionality provided by the presence of ricinoleic acid (12-hydroxyoleic acid). It has a higher viscosity than other natural oils (6 - 7 poise @ 25°C compared to 0.5 – 1 poise @ 25°C) and its viscosity only changes slightly with temperature, making it a good lubricant for fairly heavy machinery which operate at elevated temperatures. It also has a low iodine value so is not prone to oxidation. Its solidification point is also low at approx -20°C. No 1 castor oil is a technical grade and is usually the grade of choice for general lubricant applications. Firsts and pharmaceutical castor oils are the highest quality grades and are sometimes used to lubricate food machinery.
Oxidised castor oils (blown castor oil)
Castor oil can be oxidised to give a range of products, with viscosities ranging from 9 poise @ 25°C up to 1600 poise @ 25°C (also known as gelled castor oil). All grades can be used for lubricant bases and the high viscosity grades can be used in greases.
Self-emulsifiable rapeseed oil (YS 874)
Seatons self-emulsifiable rapeseed oil is ideal for use in emulsion lubricant systems. It has a lubricity similar to refined low erucic rapeseed oil and can be readily emulsified simply by adding water and agitating. Lubricant formulators could incorporate appropriate additives to suit the end application.