12-Hydroxy Stearic Acid (12-HSA) Flakes: Technical Properties and Industrial Applications

1. Technical Overview

12-Hydroxy Stearic Acid (12-HSA) is a saturated fatty acid derived from the hydrolysis of Hydrogenated Castor Oil (HCO). It is a solid, waxy organic compound characterized by the presence of both a hydroxyl group and a carboxyl group on an 18-carbon chain. This bifunctional nature allows for unique chemical versatility, making it the industry standard for producing high-performance metallic soaps and rheological additives. In industrial chemistry, 12-HSA is recognized for its ability to form stable fiber networks in non-polar fluids, which is critical for the consistency and drop-point stability of modern lubricants.

2. Chemical Structure & Composition

The chemical formula for 12-Hydroxy Stearic Acid is ¹$C_{18}H_{36}O_3$.² Structurally, it is a long-chain fatty acid with a hydroxyl (-OH) group at the 12th carbon position.³

• 12-Hydroxystearic Acid Content: Minimum 85% (Grade dependent).

• Stearic Acid Content: Residual levels optimized for melting point stability.

• Molecular Weight: Approximately 300.48 g/mol.

The combination of a polar hydroxyl group in the middle of a non-polar hydrocarbon chain creates high intermolecular hydrogen bonding, which is the primary driver of its thickening efficiency.

3. Physical & Chemical Properties

• Appearance: Hard, brittle flakes in white to cream-white color.⁴

• Melting Point: Typically ranges between 74°C and 78°C.

• Acid Value: High acid value (typically 175–185 mg KOH/g) due to the free carboxyl group.⁵

• Solubility: Insoluble in water. It is soluble in most organic solvents such as ethanol, ether, and chloroform upon heating, but precipitates or gels upon cooling.

4. Reaction Chemistry

The bifunctionality of 12-HSA allows for two primary types of reactions:

1. Carboxyl Group Reactions: Reacts with metallic hydroxides (Lithium, Calcium, Sodium) to form metallic soaps (12-hydroxystearates).⁶

2. Hydroxyl Group Reactions: Can be esterified with alcohols or reacted with isocyanates to produce specialized chemical intermediates or polyurethane additives.

3. Condensation Polymerization: Under specific heat conditions, it can undergo self-esterification to form estolides.

5. When to Use vs. When NOT to Use

Use 12-HSA Flakes when:

• Manufacturing high-temperature lithium-base or complex-base lubricating greases.⁷

• Requiring a high-purity internal lubricant for PVC or engineering plastics.⁸

• Formulating solvent-borne coatings that require anti-settling properties.⁹

Do NOT use 12-HSA Flakes when:

• The application is strictly aqueous (water-based) without high-shear emulsification.

• A neutral pH is required (12-HSA is an acid; use HCO if a neutral wax is needed).

• Transparency is critical in a solid-state application (the crystalline nature of 12-HSA creates opacity).

6. Compatibility Profile

12-HSA is compatible with a wide range of synthetic and natural waxes, including paraffin, montan, and carnauba wax. It shows excellent synergy with:

• Base Oils: Mineral oils, PAO (Polyalphaolefins), and esters.

• Resins: Acrylics, alkyds, and chlorinated rubbers.

• Additives: Synergistic with bentonite clays for hybrid thickening systems.

7. Manufacturing Process (Product Focus)

The production of high-grade 12-HSA Flakes involves:

1. Saponification & Hydrolysis: Hydrogenated Castor Oil (HCO) is reacted with an alkali and then acidified to split the triglyceride into glycerin and fatty acids.

2. Separation: The 12-HSA is separated from the glycerin-water phase.

3. Distillation & Fractionation: Advanced vacuum distillation is used to concentrate the 12-hydroxy component and achieve the desired acid value.

4. Flaking: The molten acid is solidified on a cooling belt and flaked for easy measurement and handling.

8. Technical Specifications Table

Parameter	Specification (12-HSA Flakes)
Appearance	White to Creamish Flakes
Melting Point (°C)	74 – 78°C
Acid Value (mg KOH/g)	175 – 185
Iodine Value (g I2/100g)	5.0 Max
Saponification Value	180 – 190
Hydroxyl Value	150 Min
Color (Gardner)	3.0 Max

9. Quality Grade Analysis

Nova Industries produces 12-HSA with a focus on “Hydroxyl Consistency.” Lower quality grades often contain higher percentages of palmitic or stearic acids, which lower the melting point and weaken the fiber structure in grease formulations. Our high-purity flakes ensure that the resulting lithium soap has the highest possible drop point and shear stability.

10. Impact of Impurities

• Moisture: Trace moisture can lead to inconsistent reaction times during grease cooking.

• Residual Catalyst: Excess metals can darken the product during the heating phase in cosmetic formulations.

• Unsaturated Fatty Acids: High iodine values indicate poor oxidation resistance, leading to “rancidity” or thinning of the product over time.

11. Industry-Wise Application 1: Lubricants & Greases

12-HSA is the primary raw material for Lithium 12-Hydroxystearate greases. It is preferred over standard stearic acid because the hydroxyl group allows for the formation of a superior “fibrous” thickener structure. This results in greases with higher drop points (up to 190°C) and excellent water resistance.

12. Industry-Wise Application 2: Coatings & Rheology

In the paint and ink industries, 12-HSA is used to manufacture rheological additives. It prevents the settling of heavy pigments and controls the “sag” on vertical surfaces.¹⁰ When converted into specialized diamides, it acts as a powerful anti-settling agent for solvent-borne systems.

13. Industry-Wise Application 3: Cosmetics & Pharma

In personal care, 12-HSA serves as an emollient and thickening agent for creams and ointments.¹¹ Its high melting point helps stabilize stick-based products (like lip balms) against softening in warm climates.

14. Industry-Wise Application 4: Polymers & Plastics

12-HSA acts as an internal lubricant and processing aid for various polymers, including PVC and Polystyrene.¹² It reduces the melt viscosity and improves the surface finish of extruded or molded parts without affecting the transparency of the polymer as much as other metallic stearates might.

15. Formulation Guide

• Grease Making: Add 12-HSA to the base oil and heat to ~80-90°C before adding the lithium hydroxide solution to ensure full neutralization.

• Coating Activation: For use as a thickener, it must be properly dispersed and “swollen” at temperatures between 40-55°C to develop the maximum thixotropic network.

16. Sustainability Data

12-HSA is a 100% bio-based fatty acid derived from non-edible castor seeds. It is inherently biodegradable and serves as a sustainable alternative to petroleum-derived synthetic fatty acids.¹⁴

17. Packaging & Logistics (Technical)

• Standard Packaging: 25kg HDPE/Paper bags with moisture-proof liners.

• Bulk Logistics: Available in 500kg or 1000kg Jumbo bags for high-volume industrial users.¹⁵

• Export: Palletized and shrink-wrapped to prevent flake breakage and dust generation during transit.¹⁶

18. Storage Science

12-HSA Flakes should be stored in a cool, well-ventilated warehouse. While it is a stable waxy solid, it should be kept away from strong oxidizing agents and direct heat sources. Prolonged storage above 35°C can cause the flakes to “pressure-cake,” making them difficult to handle in pneumatic conveying systems.

19. Troubleshooting Guide

• Problem: Low drop point in grease. Solution: Check for incomplete neutralization of the acid or verify that the 12-HSA hydroxyl value meets the minimum 150 specification.

• Problem: Discoloration during heating. Solution: Ensure the reaction vessel is stainless steel; trace iron contamination reacts with 12-HSA to produce dark complexes.

20. Regulatory Compliance

Our 12-HSA is REACH Compliant, ensuring it meets the stringent safety and environmental standards of the European Union. It is also listed on major global chemical inventories including TSCA (USA) and IECSC (China).

21. Safety (SDS Summary)

• Handling: Wear gloves and a dust mask to prevent skin irritation and inhalation of fine dust.

• Flammability: Non-flammable under normal conditions; flash point >200°C.

• Environment: Non-toxic; however, large spills should be contained to prevent clogging of industrial drainage systems.

22. Sample Validation Process

We recommend that procurement labs perform an Acid Value and Melting Point test as primary indicators of quality. For grease applications, a laboratory-scale cook to test the “gel strength” is the most effective validation of the hydroxyl purity.

23. Commercial Efficiency

By using Nova Industries’ high-purity 12-HSA, manufacturers can reduce the total percentage of thickener required in their formulations by 5-10%, leading to significant cost savings in high-volume production.

24. Technical FAQs

1. What is the difference between 12-HSA and Stearic Acid? 12-HSA has a hydroxyl group which provides significantly higher thickening efficiency and a higher melting point compared to standard stearic acid.¹⁷

2. Is 12-HSA compatible with mineral oil? Yes, it is widely used as a thickener for mineral oils in the lubricant industry.

3. Does it affect the clarity of plastics? At low concentrations, it acts as an effective lubricant with minimal impact on the optical properties of PVC.

25. Contact CTA

For Technical Data Sheets (TDS), safety protocols, or to request a commercial quote, please contact our export division at: export@novaind.in