Micronized Castor Wax: Technical Specifications and Advanced Rheological Applications

1. Technical Overview

Micronized Castor Wax is a highly processed, fine-powder form of Hydrogenated Castor Oil (HCO). While standard HCO is supplied in flakes, the “Micronized” grade is subjected to advanced air-jet milling to achieve a specific, ultra-fine particle size distribution (typically $d_{50}$ < 10–15 microns). In industrial R&D, this material functions as a high-performance rheology modifier and anti-settling agent. Its increased surface area allows for rapid and uniform dispersion in solvent-borne systems, where it creates a thixotropic network that prevents pigment sedimentation and sag on vertical surfaces without requiring the high temperatures needed for standard flakes.

2. Chemical Structure & Composition

Micronized Castor Wax retains the chemical identity of fully Hydrogenated Castor Oil, primarily consisting of the triglyceride of 12-hydroxystearic acid.

• Tri-12-Hydroxystearin: ~85%–90%.

• Physical State: Fine, micronized crystalline powder.

• Functional Benefit: The secondary hydroxyl groups are highly accessible in this micronized form, facilitating strong hydrogen bonding that drives the formation of a thixotropic gel structure.

The micronization process is strictly mechanical and thermal, ensuring no chemical degradation of the hydroxyl functionality or the saturated hydrocarbon chains.

3. Physical & Chemical Properties

• Appearance: Fine white powder.

• Melting Point: 85°C to 88°C.

• Particle Size ($d_{50}$): 5 µm to 20 µm (Customizable grades).

• Acid Value: <3.0 mg KOH/g.

• Iodine Value: <5.0 g $I_2$/100g (fully saturated).

• Bulk Density: Low (typically 0.3 to 0.5 g/cm³), indicating a very high surface-to-volume ratio.

4. Reaction Chemistry (Rheological Activation)

Micronized Castor Wax functions through physical interaction rather than chemical reaction:

1. Dispersion: Due to the fine particle size, it disperses easily into the liquid phase under high-shear mixing.

2. Activation: When the system is heated to its activation temperature (usually 35°C–55°C depending on the solvent), the particles “swell” and partially dissolve.

3. Network Formation: Upon cooling under controlled shear, the hydroxyl groups form a three-dimensional “house-of-cards” fiber network that traps pigments and provides sag resistance.

5. When to Use vs. When NOT to Use

Use Micronized Castor Wax when:

• Manufacturing high-quality powder coatings requiring a smooth, pinhole-free finish.

• Formulating solvent-borne paints and inks where high-shear dispersion is available but high-temperature cooking is undesirable.

• Producing specialized greases requiring a very fine thickener dispersion for high-speed bearings.

Do NOT use Micronized Castor Wax when:

• The system is purely water-based (it is highly hydrophobic; use an emulsified version instead).

• The formulation will be processed at temperatures exceeding 90°C during the dispersion phase, which may cause the wax to melt completely and lose its rheological efficiency upon uncontrolled cooling.

6. Compatibility Profile

• Solvents: Highly effective in aliphatic and aromatic hydrocarbons, esters, and ketones.

• Resins: Excellent compatibility with epoxy, alkyd, polyester, and chlorinated rubber resins.

• Synergy: Can be used alongside organoclays to provide a balanced anti-settling and anti-sag profile.

7. Manufacturing Process (Product Focus)

Nova Industries produces Micronized Castor Wax using a specialized cold-milling technology:

1. Feedstock: Only premium, high-melting-point HCO flakes are used.

2. Cryogenic/Air-Jet Milling: The flakes are pulverized using high-velocity air streams. The temperature is strictly controlled to prevent the wax from melting or “caking” during the process.

3. Classification: An integrated air classifier ensures that only particles meeting the specific micron-size target are collected, while oversized particles are returned for further milling.

4. Anti-Caking Treatment: A trace amount of silica or other flow aids may be added to maintain the free-flowing nature of the powder.

8. Technical Specifications Table

Parameter	Specification (Micronized Grade)
Appearance	Fine White Powder
Melting Point	85°C – 88°C
Mean Particle Size ($d_{50}$)	10 µm – 15 µm
Acid Value (mg KOH/g)	3.0 Max
Iodine Value (Wijs)	5.0 Max
Hydroxyl Value	150 – 165
Moisture Content	0.5% Max

9. Quality Grade Analysis

Nova Industries monitors Particle Size Distribution (PSD) via laser diffraction. A narrow PSD is critical; if the particles are too large, the coating will have “seeds” or grit. If they are too fine, the product may become difficult to handle due to excessive dusting or may cause an unwanted increase in the initial viscosity of the paint.

10. Impact of Impurities

• Residual Flakes: Large particles can cause surface defects and “craters” in powder coatings.

• Low Melting Point Fractions: If the hydrogenation is incomplete (high iodine value), the wax may soften prematurely, leading to poor shelf stability of the finished paint.

11. Industry-Wise Application 1: Powder Coatings

Used as a degasifying agent and flow modifier. It helps in the release of entrapped air during the curing process, preventing pinholes and improving the overall surface gloss and “mar resistance” of the coating.

12. Industry-Wise Application 2: Printing Inks

In offset and gravure inks, Micronized Castor Wax provides rub resistance and slip. It ensures that the printed surface can withstand mechanical handling without smudging while maintaining the desired tack.

13. Industry-Wise Application 3: Sealants & Adhesives

Acts as a powerful thixotropic agent in PVC plastisols and automotive underbody sealants. It allows the sealant to be easily extruded but prevents it from “running” or dripping once applied to the vertical seams of the vehicle.

14. Industry-Wise Application 4: Cosmetic Powders

Due to its fine texture and emollient nature, it is used in specialized pressed powders and eye shadows to improve skin adhesion and provide a smooth, velvety feel.

15. Formulation Guide

• Dispersion: Add the micronized powder early in the pigment-grind stage to ensure full de-agglomeration.

• Temperature Management: Ensure the “activation temperature” is reached during the milling process to develop the thixotropic network. For most solvent systems, 45°C–50°C is the “sweet spot.”

16. Sustainability Data

Micronized Castor Wax is a 100% bio-based material. It provides a sustainable, renewable alternative to synthetic polyolefin waxes and fumed silica in rheological applications.

17. Packaging & Logistics (Technical)

• Standard: 15kg or 20kg Multi-wall paper bags with PE liners.

• Logistics: Classified as non-hazardous. Due to the high surface area, it should be kept away from strong odors and moisture.

18. Storage Science

Store in a cool, dry place (below 30°C). Because it is a micronized powder, it is sensitive to “pressure caking.” Avoid stacking pallets too high and keep away from hot walls or steam pipes in the warehouse.

19. Troubleshooting Guide

• Problem: Grit or “seeds” in the paint. Solution: Check the dispersion shear; if the powder is not fully de-agglomerated, it will remain as seeds.

• Problem: Loss of sag resistance. Solution: The activation temperature might have been exceeded, causing the wax to dissolve completely and fail to form a fiber network upon cooling.

20. Regulatory Compliance

Our Micronized Castor Wax is REACH Compliant, meets FDA requirements for indirect food contact (packaging), and is listed on all major international chemical inventories.

21. Safety (SDS Summary)

• Dust Hazard: As with any fine powder, take precautions against dust explosions. Ensure all equipment is grounded.

• Handling: Wear a dust mask and safety goggles.

• Fire: Use water spray, CO2, or dry chemical.

22. Sample Validation Process

Test the Particle Size ($d_{50}$) and Melting Point. For coating manufacturers, a “Hegman Gauge” test in a standard solvent/resin mix is the most effective way to verify the dispersion quality and absence of grit.

23. Commercial Efficiency

By using Nova Industries’ Micronized Castor Wax, manufacturers can achieve superior rheology with shorter mixing times and lower energy consumption compared to using standard HCO flakes. The consistent particle size leads to a higher “First-Pass Quality” rate in the production of high-end paints and inks.

24. Technical FAQs

1. Can I replace fumed silica with Micronized Castor Wax? Yes, in many solvent-borne systems, it provides similar anti-sag properties with improved pigment wetting and flow.

2. Does it affect the color of the paint? No, it is a white powder that becomes transparent once properly activated and dispersed in the resin.

3. What is the shelf life? 24 months if stored correctly in a cool, dry environment.

25. Contact CTA

For Technical Data Sheets (TDS), specific micron-size requests, or to request a sample of our Micronized Grade, please contact our technical sales team at: export@novaind.in