Kao Develops Technology to Achieve Fine Fiber Functionality in Skincare Formulations

Kao Corporation (President and CEO: Yoshihiro Hasebe) has successfully developed a skincare formulation using cellulose microfiber*2, which applies its "Fine Fiber Technology*1." This new formulation replicates the film-forming functions of conventional fine fiber films. The cellulose microfiber incorporated into the formulation forms a unique network structure after application, creating a uniform film. This film is resistant to sweat and sebum, exhibits high durability, and suppresses moisture evaporation from the skin. Furthermore, it was confirmed that continuous use increases stratum corneum hydration.

This breakthrough enables the realization of fine fiber film functions, previously only achievable by combining with skincare formulations, using skincare formulations alone.

Network structure formed after application of the formulation containing the new material.

Part of this research was presented at the 51st Annual Meeting of the Society of Cosmetic Chemists of Japan (June 25-26, 2026, Tokyo).

*1 Kao News Release, November 27, 2018: "Development of 'Fine Fiber Technology'"

*2 Short fibers with an average fiber diameter of 1μm developed by Asahi Kasei Corporation.

Background

In 2018, Kao developed "Fine Fiber Technology," which involves directly spraying ultra-fine fibers with a diameter of 1μm or less onto the skin using a dedicated device, forming an ultra-thin film of overlapping fibers on the skin. It has since been revealed that this film uniformly holds formulations through the high capillary action of the ultra-fine fibers and suppresses moisture evaporation*3. In recent years, to expand its applications and scope, Kao has also developed technology to form these fibers into sheets, in addition to the direct spraying method*4.

However, both the spray-type and sheet-type methods require combination with skincare formulations. Therefore, Kao has been working on developing technology to apply fine fibers to formulations, aiming for a more user-friendly form.

*3 Kao News Release, September 4, 2019: "Stratum Corneum Protein Expression Behavior and Skin Effects of Films Formed by Fine Fibers and Formulations"

*4 Kao News Release, May 29, 2025: "Development of Large Fine Fiber Sheets Integrated with Non-woven Fabric"

New Material Applying Fine Fiber Functionality, Compatible with Skincare Formulations

To exert the functions of fine fibers within a formulation, it is necessary to stably disperse the ultra-fine fibers in the formulation and for them to form a network structure after application. However, achieving both of these with existing ultra-fine fibers was difficult.

Kao therefore began searching for materials and shapes that could achieve both stable dispersion in formulations and network formation after application. Focusing on cellulose fibers as a material suitable for uniform film formation, which are difficult to dissolve in water or oil within the formulation, Kao collaborated with Asahi Kasei Corporation.

Asahi Kasei Corporation achieved fine cellulose fibers with an average fiber diameter of 1μm through its advanced spinning technology, and both companies optimized factors such as fiber length. As a result, they identified the optimal fiber shape that disperses stably in the formulation and forms the characteristic fine fiber network structure after application (Figure 1).

Figure 1. Cellulose microfiber optimized for incorporation into skincare formulations.

Characteristics of Formulations Containing the New Material

Forms a Uniform and Highly Durable Film

When the developed cellulose microfiber was incorporated into a skincare formulation and the resulting film after application was observed using a scanning electron microscope, the formation of a network structure by the cellulose microfiber was confirmed.

While conventional formulations tend to have uneven application, the new material-containing formulation formed a uniform film. Furthermore, this film exhibited high resistance to rubbing, as well as resistance to sweat and sebum, demonstrating high durability.

Suppresses Moisture Evaporation from the Skin

Five Japanese women aged 20-50 were recruited for a study where the new material-containing formulation and a formulation without the new material were applied to the left and right halves of their faces, respectively. The change in transepidermal water loss (TEWL) over time was measured. The results showed that the new material-containing formulation had lower TEWL 6 hours after application compared to the formulation without the new material, confirming that moisture evaporation was suppressed (Figure 2). This is thought to be because the uniform film evenly covers the skin surface without gaps for an extended period.

Figure 2. Moisture evaporation suppression effect of the new material-containing formulation.

Increases Stratum Corneum Hydration with Continuous Use

Eleven Japanese men and women aged 20-40 participated in a study where the stratum corneum condition of their inner forearms was temporarily impaired. They then continuously applied either the new material-containing formulation or the formulation without the new material for four days. A comparison of the change in conductance, an indicator of stratum corneum hydration, showed that the area where the new material-containing formulation was applied had higher conductance after four days, indicating an increase in stratum corneum hydration (Figure 3).

Figure 3. Change in stratum corneum hydration with the new material-containing formulation.

Conclusion

By using cellulose microfiber developed by Asahi Kasei Corporation, Kao has succeeded in achieving the functions of a fine fiber film, which previously required combination with skincare formulations, using skincare formulations alone.

Kao will continue to strive to create new value that addresses consumers' skin concerns.