Manufacturing of Sunblocks with a Mixer

In recent years, there has been a significant surge in the manufacturing of sunblocks due to the growing awareness about the harmful effects of UV rays and the importance of protecting our skin. This increased awareness has given rise to the demand for specialized sunblock products, including water-resistant formulas, infant formulas, and those with higher sun protection factors (SPF).

The manufacturing techniques employed in this industry are crucial in adapting to the evolving market demands while ensuring optimal performance of the ingredients.

Sun creams and lotions are manufactured using either oil-in-water or water-in-oil emulsions. These products contain a range of ingredients such as emollients, lubricants, emulsifying and thickening agents, perfume, color, preservatives, and UV filters. The effectiveness of UV protection in these products is directly influenced by the quality of dispersion and particle size of the UV filters and absorbers, such as titanium dioxide or zinc oxide.

Most sunscreen products are produced in the following manner:

• Powdered ingredients, such as cetyl alcohol and stearic acid are typically dispersed into the oil phase. The water phase is prepared separately, containing emulsifiers and stabilizers (Carbomers, Cellulose Gums, Hydrocolloids)
• The oil phase and water phase are then mixed to form an emulsion. Depending on the formulation, some applications may require heating 110 - 185°F (45 - 85°C)
• Depending on the formulation, the UV filters and absorbers are supplied as a powder and can be dispersed into either the water or oil phase before or after the emulsion is formed
• Mixing is continued until the end product is homogeneous.

Using conventional mixers and agitators several challenges arise:

• Additives designed to thicken the product are by nature liable to form agglomerates, which a conventional mixer cannot easily break down
• Partially hydrated ingredients can build up on the vessel walls and mixer shaft
• Emulsions are not easily formed with conventional agitators even with the addition of heat. The addition of emulsifiers, stabilizers and certain additives can reduce the SPF of the lotions. For this reason, it is important to use the minimal ingredients required to create a stable emulsion
• UV absorbers are supplied in micronized form. Conventional agitators are not capable of breaking the components down to their individual particle sizes
• Long batch times and often additional equipment are required to achieve satisfactory consistency
• Significant air entrainment occurs as a result of the incorporation of powders from the liquid surface.

Quadro's Approach to Manufacturing Sunblock

Quadro recommends the combined use of a Ytron^® ZC Powder Disperser and a Ytron^® Jet Mixer. The ZC is designed to disperse extremely difficult-to-wet powders in a single pass without lumps or 'fisheyes'.

The incorporation of the powder can be easily achieved by adding either the water or oil phase to the processing vessel or by utilizing a recirculation loop from the vessel. This process is made possible by the presence of a powerful vacuum in the reactor, created by a liquid ring seal between the rotor and stator.

The powders are then subjected to sufficient shear, ensuring complete dispersion in a single pass before being returned to the processing vessel. Once the second phase is added, the Jet Mixer facilitates a thorough mixing from top to bottom, guaranteeing a homogeneous blend and a perfectly finished emulsion.

Advantages of using Quadro's approach to manufacturing sunblock include:

• Consistent and reliable product quality from batch to batch, thanks to the efficient single-pass processing method.
• Enhanced sun protection due to the improved dispersion of micronized oxides, resulting in a higher SPF.
• Lump-free lotions that maximize the utilization of raw materials and contribute to a better SPF.
• Elimination of the need for premixing powdered ingredients, saving time and streamlining the manufacturing process.
• Rapid mixing times, ensuring quick and efficient production.
• The formation of a stable emulsion leads to a well-blended and high-quality end product.