Solubility Study of Oil-Soluble UV Filters: Effects of Different Ester Systems on Sunscreen Compatibility and Formulation Performance

With the development of sunscreen products in the direction of high protection, refreshing skin feeling, stability and transparency, the compatibility between sunscreen agents and between sunscreen agents and oil system has become a key link in formula development. Especially in high SPF formula, sunscreen spray, sunscreen oil and light emulsion system, the solubility of sunscreen directly affects the stability, skin feel, crystallization risk and final sunscreen performance of products.

Recently, Suzhou Sunland Pharmatech Co., Ltd. carried out a systematic solubility test for its ShieldBiso^TM series oil-soluble sunscreen agents, focusing on the solubility of different liquid ester solvents to various sunscreens, providing more practical data reference for the development of sunscreen formulations.

I.Test Description

This test uses different liquid esters as solvents to test the maximum solubility (g) of ShieldBiso^TM series sunscreen in 100g liquid solvent.

 II.Analysis of test results

1.ShieldBiso^TM IMC shows excellent solubility.

As can be seen from the data, ShieldBiso^TM IMC has strong solubility for various solid sunscreens.In particular, the solubility of ShieldBiso^TM A-Plus reaches ≥100g, which shows that it has obvious advantages in high-load UVA sunscreen system.

✓Application value

ShieldBiso^TM IMC is suitable for:

• High SPF sunscreen lotion
• Suntan oil
• Clear sunscreen spray
• High UVA formula system

✓Its excellent solubility is helpful to:

• Reduce crystallization risk
• Improve system stability
• Improve the transparency of the formula
• Optimize skin feeling

2.ShieldBiso^TM HEB exhibits excellent compatibility with various ester-based systems

The solubility of ShieldBiso^TM HEB in various esters is generally high, which shows that HEB has very good compatibility in the polyester system.

✓Application advantage

ShieldBiso^TM HEB is suitable for:

• High power sunscreen products
• Long-lasting water-resistant sunscreen
• Outdoor sports sun protection
• Sunscreen stick and anhydrous system

✓At the same time, it is beneficial to realize:

• Higher activity addition
• More stable oil phase system
• Lower crystallization probability

3.ShieldBiso^TM XL has a balanced performance in multiple systems.

The solubility of ShieldBiso^TM XL in a variety of liquid solvents is generally balanced. Compared with some sunscreens that are highly dependent on specific solvents, the broad-spectrum compatibility of ShieldBiso^TM XL is more suitable for compound development.

✓Suitable direction

• Multi-sunscreen compound system
• Light emulsion
• Daily commuting sunscreen
• High transparency formula

4.The solubility of ShieldBiso^TM PS15 is relatively limited.

The test data show that the solubility of ShieldBiso^TM PS15 in most systems is low, indicating that it needs to be more careful in solvent matching and system design in high concentration formulations.

✓Suggestion:

• Used in combination with highly polar esters.
• Control the addition ratio
• Adopt a compound solubilization scheme

III.Application Characteristics of Different Ester Solvents

1.C12-15 Alkyl Benzoate

It has strong solubility (≥80g) for ShieldBiso^TM HEB, and also has:

• Thin skin feeling
• Good spreadability
• Low greasy feeling

It is one of the classic solvents in the current sunscreen system.

2.Dioctyl Carbonate

It shows good solubilization ability in many sunscreens, especially for ShieldBiso^TM HEB ≥80g. At the same time, the skin feels dry, which is suitable for:

• Refreshing sunscreen
• Oil skin formula
• Sunscreen products in summer

3.Propyl heptyl octoate

Combine high solubility and excellent skin feeling balance, and is very suitable for:

• Lightweight sunscreen lotion
• Sunscreen spray
• Pre-makeup sunscreen products

IV.Conclusion

With the increasing demands of consumers for high protection, light skin feeling and stability, the compatibility and dissolution of sunscreens are becoming more and more important.

The solubility test of ShieldBiso^TM series sunscreens provides valuable data support for formulation engineers in the following directions:

›Screening of sunscreen

›Optimization of solvent system

›High SPF development

›Cool skin feeling design

›Risk control of crystallization

In the future, Suzhou Sunland Pharmatech Co., Ltd. will continue to carry out more technical tests around the application research, system stability and innovative formula of sunscreen, and provide the market with higher performance and higher stability sunscreen solutions.