Diglycerin (Diglycerol) is a clear, colorless liquid that is more dense than Glycerin. Diglycerol has been incorporated into personal care products in Japan since the 1980s. It is a mild humectant, provides gloss to hair, and can enhance fragrance/flavor impact and longevity.
The moisturizing properties of Diglycerin are comparable to Glycerin's effects. Its water-binding ability is weaker but has a prolonged hydrating effect as Diglycerol's adsorption takes longer. Their combinations deliver a balanced effect, so they are used together in many moisturizing applications.
Diglycerin enhances the fragrance performance and is used in oral care and deodorant formulations. In dentifrices and mouthwashes, it improves the impacted flavor and longevity of cooling and fresh breath sensation. The effect was comparable to what can be obtained by using more expensive encapsulation technology. Diglycerin also increases fragrance longevity in deodorant sticks and has a more substantial perfume impact on the formulation.
Easing application and improving skin feel, Diglycerin reduces tackiness and stickiness during the application, providing a pleasant after-feel. It has reduced irritation potential and can replace other solvents with irritation potential in deodorant stick formulations.Diglycerinis is used in many hair care products to provide more moisture to the hair. It also enhances hair gloss, providing a "wet look" without leaving a sticky feeling.
Comparison with Glycerin
Skin moisturization is a balancing act since a humectant can draw moisture from the air or from the skin, causing dehydration. Glycerin has strong water-binding properties, making it a good moisturizer in many formulations. However, glycerin’s moisturization ability has limitations:
- In low humidity or extreme weather conditions such as excessive wind or sun, glycerol tends to draw moisture from the deeper layers of the skin, thus drying it from the inside out. This is of particular concern in lip treatment products, which are used to protect the skin from harsh environments.
- Under xerotic conditions such as deep wrinkles and dry or squamous skin, glycerin tends to increase dryness by binding water from the stratum corneum.
- In the case of particularly sensitive skins, milder humectants are required.
Diglycerin has a lower hydroxyl number than glycerin, which imparts a lower water-binding ability to the product. Being a bigger molecule, diglycerin has a lower moisture absorption rate and is retained on the skin surface for a more extended period. Thus, compared to glycerin, diglycerol absorbs less water from the human skin more slowly.
Other uses
Esters produced from Diglycerin and other polyglycerols are also used to formulate various cosmetic and personal care products. Many esters can be included as excipients in OTC (over-the-counter) topical drugs such as antibacterial creams and antidandruff shampoos. They function as emulsifiers, dispersants, solubilizers, thickeners, emollients, conditioners, and spreading agents.
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