The Application of Pentylene Glycol in Cosmetics

Basic information

INCI name：PENTYLENE GLYCOL

CAS Number：5343-92-0

Pentylene glycol, also known as 1,2-pentylene glycol, is a highly versatile and extensively utilized cosmetic ingredient. It boasts remarkable moisturizing capabilities akin to those of diols. Beyond its hydration prowess, this compound offers a multitude of additional benefits. It possesses antibacterial properties, which can help maintain the integrity and longevity of cosmetic formulations by inhibiting the growth of bacteria. Additionally, pentylene glycol functions as a solubilizer, enhancing the compatibility and stability of various ingredients within a product. It also promotes penetration, allowing other active ingredients to more effectively reach the target layers of the skin.

In the realm of sun protection, pentylene glycol plays a crucial role in bolstering the water resistance of sunscreen formulas. This ensures that the sunscreen remains effective even when exposed to water, providing more reliable and long-lasting protection against harmful UV rays. When incorporated into emulsion-based formulations, pentylene glycol (or 1,2-pentylene glycol) imparts a refined appearance to the product. Its presence contributes to an improved texture and a pleasing skin feel, enhancing the overall sensory experience for the user. In essence, pentylene glycol is a multifunctional component that elevates the performance and appeal of a wide array of cosmetic products.

Specification

Features

♣♣ Moisturizing Properties 

Pentylene glycol is an excellent humectant, meaning it binds well to water, making it a good hydrating agent. It helps to hydrate the skin by retaining moisture, preventing dryness and leaving the skin soft and smooth. This dual-action moisture preservation helps cosmetics to remain fresh, effective, and invitingly luxe on your skin.

Pentylene glycol contains two hydroxyl groups, giving it excellent moisturizing properties, which are superior to other diols. Patent W01995/001151 reports that Pentylene glycol acts as a moisturizing active substance in cosmetics, with a dosage range of 2%–5%, showing significant skin hydration effects. Clinical studies have shown that a formula with 5% Pentylene glycol increases skin water content by approximately 30% compared to a placebo. Another clinical study compared the moisturizing effects of Pentylene glycol and propylene glycol. In two o/w emulsions, one containing 5% Pentylene glycol and the other 5% propylene glycol, the result showed that the formula with Pentylene glycol increased skin hydration by nearly 90% compared to the propylene glycol formula. Patent EP1078638 describes in detail how Pentylene glycol can enhance the water resistance of sunscreen formulas. Research indicates that formulations containing Pentylene glycol have better water resistance than those containing propylene glycol or Pentylene glycol.

♣♣ Antibacterial Properties

In addition to its moisturizing effects, pentylene glycol has mild antibacterial properties. It helps prevent the growth of harmful microorganisms like bacteria and fungi in cosmetic products, extending their shelf life. This makes it a valuable ingredient for maintaining the stability and safety of skincare formulations.

Pentylene glycol exhibits excellent broad-spectrum antimicrobial activity. It effectively inhibits gram-positive and gram-negative bacteria, yeast, and mold, but it is not classified as a preservative. Therefore, products that use it alone can claim to be preservative-free. It also has a good synergistic effect with other commonly used preservatives and can be used as a preservative booster to reduce the amount of traditional preservatives and minimize their irritant effects. Studies show that the minimum inhibitory concentration (MIC) of Pentylene glycol is significantly lower than that of other diols, indicating its high antimicrobial activity. Pentylene glycol has broad-spectrum bactericidal effects on both gram-positive and gram-negative bacteria, yeast, and mold. Experiments have shown that when combined with small amounts of other preservatives, the antimicrobial activity of Pentylene glycol can significantly enhance the preservative's efficacy. Its boosting effect is notably superior to that of 1,3-butanediol. Pentylene glycol is effective against E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and marine fungi. At a concentration of 3.2%, it can inhibit microbial growth, improve antimicrobial activity, and reduce the amount of preservatives, making the product safer and gentler.

♣♣ Solubilizing and Penetration-Enhancing Effects

Pentylene glycol serves as a solvent for various cosmetic ingredients, ensuring that the product has a uniform texture and consistency. It also helps improve the absorption of other active ingredients into the skin, enhancing the overall effectiveness of the product. This feature is integral in maintaining the texture and consistency of products.

Cosmetic emulsion formulations typically consist of two immiscible liquid phases: one as the continuous phase, while the other is dispersed as small droplets within it. The particle size and its distribution of the emulsion are key parameters in cosmetic formulations. A uniform, fine, and evenly distributed emulsion particle system tends to be more stable, less prone to aggregation, spreads well, and has a finer appearance. Since Pentylene glycol contains both hydrophilic and lipophilic groups, it is soluble in both water and many oils, making it an effective solvent for many cosmetic ingredients. In essence, it helps enhance the system's transparency, while its unique amphoteric structure provides good skin permeability, thereby helping active ingredients penetrate the stratum corneum of the skin and increasing the utilization of active ingredients. When preparing emulsions, the use of 1-5% Pentylene glycol in the formulation significantly improves the product's sensory characteristics and skin feel. A formulation with 1% Pentylene glycol has a noticeably smaller particle size compared to a formulation without it. Formulations with 3% and 5% Pentylene glycol have even smaller particle sizes than those without it, and the emulsion has a less greasy feel compared to other polyol formulations. Additionally, Pentylene glycol can enhance the dispersion of powders, making skincare or sunscreen products appear whiter and more glossy.

Application

♣♣ Pentylene glycol as a multi-functional additive can be used in creams, lotions,toners, wipes and other personal care products;

♣♣ It has the functions of moisturizing, moisturizing, solubilizing, stabilizing emulsion and Inhibition of microbes and synergistic;

♣♣ Pentylene glycol is stable to light, heat and a wide pH range (2~12);

♣♣ By Cosmetic Ingredient Review (CIR), pentylene glycol is classified as "S" by Cosmetic Ingredient Review (CIR). It can be used in concentrations up to 5% and is compatible with various commonly used cosmetic ingredients.

♣♣ The recommended dosage is 0.5-2.0%.

Partial List of Products Containing Pentylene Glycol

Safety Assessment Information

Used for over ten years;

Skin irritation: Almost none;

Eye irritation: Almost none;

Skin allergy (sensitization): Almost none.

Highest Historical Usage Level: Leave-on products (21.29%)

Authoritative Agency Evaluation Conclusion:The Cosmetic Ingredient Review (CIR) published an evaluation report on this substance, detailing its usage concentration in marketed products: for rinse-off products, the concentration ranges from 0.001% to 5%, and for leave-on products, it ranges from 0.005% to 5%. The CIR concluded that the ingredient is safe for use in cosmetics under the current usage conditions.

Reference:Safety Assessment of 1,2-Glycols as Used in Cosmetics. Published report 2012 available from CIR. International Journal of Toxicology 31 (Supplement2) 147S-168S.