Low HLB
Emulsifier core strength-Span series (Sorbitan esters)
In the field of cosmetic raw materials nonionic surfactants, compared with the Twain series with high public awareness, the Span series is widely used, but it is rarely well-known to people outside the industry.So, what kind of raw materials is the Span series?Why can it occupy an important position among many emulsifiers and become the right-hand man for the deployment of high-oil phase and stable systems?
From the industry definition point of view, the Span series usually refers to a class of nonionic surfactants, the common name of which is Sorbitan esters.The name ”Span" is derived from the transliteration of its trade name “Span”. Since it was successfully developed by Atlas in the 1940s, after decades of popularization and application, this common name has been deeply rooted in the hearts of the people and has become a conventional name in the industry. It is simple, easy to remember and highly recognizable.In actual production and formulation applications, the industry is more accustomed to calling different types of products in the form of “Span+number”. Among them, Span 20, Span 40, Span 60, Span 80, and Span 85 are the five core models that are currently the most widely used and the most in demand in the market. Each has unique characteristics and adapts to the formulation needs of different scenarios.
Tracing back to the essence and structural source of the Span series, its core definition is clear and clear: it is a fatty acid ester surfactant that is esterified with fatty acids after Sorbitan is dehydrated to form Sorbitan.Compared with the Tween series, which is also a nonionic surfactant, the core difference between the Span series is that there is no polyoxyethylene chain in its molecular structure-this structural difference directly determines that the hydrophilicity of the Span series is lower than that of the Tween series, which in turn leads to its low HLB value and overall preference for the oil phase. It also creates its unique advantages in the oil in water system and the high-oil matching formula, which complement each other with the Tween series to jointly meet the emulsification needs of different systems.
From the point of view of structural composition, the molecular structure of the Span series is relatively simple, and it is mainly composed of two parts: first, Sorbitan, which is generated by Sorbitol after dehydration reaction, is the basis for forming the molecular skeleton of the Span, and its own hydroxyl group structure provides the necessary conditions for the subsequent esterification reaction with fatty acids.The second is fatty acids. Different types of division plates use different sources of fatty acids. The common ones are Lauric acid, Palmitic acid, Stearic acid, Oleic acid, etc. This is also the core key to distinguish different Span models and determine their characteristic differences.It is worth mentioning that with the continuous optimization of the production process, the preparation of the Span series can now effectively reduce the reaction energy consumption by optimizing the dehydration temperature and introducing a phase transfer catalyst, improving product purity, solving the problems of dark color and high viscosity in traditional processes, and promoting the development of Span products in the direction of high quality.
From the perspective of formula application, the core characteristics of the Span series are very outstanding. With its three core advantages, it has become a just-needed raw material in multi-industry formulas. Its advantages are not only reflected in the emulsifying performance, but also in terms of compatibility, stability, etc. It shows strong competitiveness and adapts to the demanding needs of different scenarios.
As a nonionic surfactant, the primary advantage of the Span series is its excellent compatibility and electrolyte stability.Unlike ionic surfactants, Span series molecules are not charged, which makes it well compatible with cationic and anionic surfactants, various active ingredients, and functional raw materials. There is no need to worry about the stratification, precipitation, turbidity and other problems of the formula, which reduces the difficulty of formula development.At the same time, it is not sensitive to electrolytes. Even in formulas containing electrolytes such as salts and minerals, it can maintain stable emulsifying and dispersing properties, and will not affect the product effect due to the presence of electrolytes. This characteristic enables it to be widely used in all kinds of complex systems, whether it is high-salt formulas in cosmetics or electrolyte systems in the industrial field, it can play a stable role.In addition, the complex combination of Span series and other emulsifiers is extremely flexible. It can not only be combined with Tween series to achieve precise adjustment of HLB value, but also work synergistically with other non-ionic and ionic emulsifiers to further improve the stability and emulsification effect of the system to meet the performance requirements of different products.
The low HLB value and partial oleophilicity are the most recognizable core characteristics of the Span series, and they are also the key to distinguishing it from the Tween series.The typical HLB value range of the Span series is about 1.8-8.6, which is much lower than that of the Tween series (14-17), which means that its oleophilicity is much greater than that of hydrophilicity, and it is more suitable as an emulsifier for O/W emulsions.In practical applications, this characteristic allows the Span series to show an irreplaceable advantage in high-oil-compatible, thick creams-it can evenly disperse the aqueous phase components in the oil phase system to form an oil in water emulsion with delicate texture and strong stability.At the same time, due to its oleophilic characteristics, the Span series can also be used for oil phase dispersion to help the oily components disperse evenly and prevent their aggregation and precipitation. In addition, it can be combined with high HLB emulsifiers (such as the Tween series) to accurately adjust the HLB value of the system and adapt to the emulsification needs of different oils and fats, further broadening its application scenarios.
Improving the emulsification stability is another core advantage of the Span series, and it is also an important reason for its wide application in many industries.Span series is often used as the main emulsifier or synergistic emulsifier, especially suitable for improving the oil phase carrying capacity and system stability-in high-oil phase creams, sunscreen creams, cold creams and other products, Span series can effectively wrap the oil phase components to form a stable emulsified film, prevent oil-water stratification, and extend the shelf life of the product.In the industrial field of lubricating oil emulsification, metalworking fluids, agrochemicals and other systems, it can improve the high temperature resistance and anti-aging properties of the system, and ensure that the product still maintains stable performance in complex environments.According to industry data, the Span series, as the core category of emulsifiers, occupies 4.8% of the global emulsifier market and accounts for about 6% of the food emulsifier segment. Its stable emulsifying properties have been widely recognized by various industries.
Among the many models of the Span series, the five large models of Span 20, Span 40, Span 60, Span 80, and Span 85 are more common. Due to different sources of fatty acids, they have obvious differences in HLB values, characteristics, and application scenarios, and are accurately adapted to the formulation requirements of different industries and products. The following combines the core parameters and practical applications of each model to analyze its differences and advantages in detail.：
Span 20 (INCI name is sorbitan laurate), the source of fatty acids is lauric acid, and the HLB value is 8.6. It is the one with the highest HLB value and relatively hydrophilic among the five large models.The core characteristics of this model are strong emulsifying and dispersing ability, good compatibility with the oil phase, mild and non-irritating. Although it is oleophilic, the hydrophilicity is the most prominent in the Span series. Therefore, it is often used as an auxiliary emulsifier. It can also be used alone in some low-oil phase oil-in-water systems.In practical applications, Span 20 is widely used in makeup remover oil, makeup foundation, cream mask, hair care essential oil, body massage oil and other products in the field of cosmetics.
Span 40 (INCI name is sorbitan palmitate), the source of fatty acids is palmitic acid, the HLB value is 6.7, the emulsifying stability is excellent, it is suitable for medium and high oil phase systems, and the temperature resistance is good. It is one of the commonly used models in cosmetic cream products.The core feature of this model is stable emulsification, which can form a delicate and viscous emulsion, and has good compatibility with waxes and oils. It is especially suitable for moisturizing creams, hand creams, hair masks, makeup eyeshadow, solid perfumes and other products.
Span 60 (INCI name is sorbitan stearate), the source of fatty acids is stearic acid, the HLB value is 4.7, the emulsifying power is strong, and it can form a stable paste. It is a model commonly used in O/W emulsions in the Span series.The core advantage of this model is strong stability, can maintain a stable emulsifying effect over a wide temperature range, acid and alkali resistance, electrolyte resistance, suitable for high oil phase, high waxy system, widely used in high moisturizing creams, lipsticks, hair waxes, body creams, makeup concealers and other cosmetics, can provide good moisture and stability for the product.
Span 80 (INCI name is sorbitan oleate), the source of fatty acids is oleic acid, with an HLB value of 4.3, strong emulsification and permeability, refreshing skin feeling, and good compatibility with vegetable oils. It is the most commonly used Span model in mobile oil phase systems.The core feature of this model is its strong oil-dissolving ability, which can quickly emulsify all kinds of vegetable oils and mineral oils. It is suitable for use in oil in water systems with strong fluidity. It is widely used in makeup remover oils, refreshing lotions, hair care essential oils, body creams, sunscreens and other products in the field of cosmetics. It can not only achieve good emulsifying effect, but also ensure the refreshing skin feeling of the product and avoid greasy feeling.
Span 85 (INCI name is sorbitan trioleate), the source of fatty acids is oleic acid (triester), and the HLB value is only 1.8. It is the lowest HLB value and highly oleophilic emulsifier among the five large models.The core characteristics of this model are extremely oleophilic and excellent emulsifying ability. It is suitable for use in systems with high oil phase and high viscosity. It can effectively carry a large number of oily ingredients and prevent oil-water stratification. It is widely used in heavy face creams, body creams, conditioners and other products in the field of cosmetics, which can provide excellent moisture and stability for the product.
It is worth noting that although the five core models of the Span series have different characteristics, they are all classic O/W emulsifiers. They can be flexibly combined with each other, or they can be combined with other emulsifiers such as the Tween series to achieve precise adjustment of the target HLB value, and then formulate an emulsion that is ion-resistant, acid-base-resistant, long-term stable viscosity and delicate appearance, which greatly enhances the flexibility and adaptability of the formula.The recommended dosage of Span series in the formula is usually 1%-5%. The specific dosage can be adjusted according to the product type, formula requirements and the proportion of other ingredients, which can not only ensure the emulsifying and stabilizing effect, but also avoid the skin feeling or performance of the product due to excessive dosage.
From the point of view of commercial positioning, the essence of the Span series is a class of low HLB, nonionic, partial oil phase sorbitan fatty acid ester emulsifier system. In the B2B product system, its positioning is clear and clear, mainly as
Oil in water emulsifier、Lipophilic Surfactant、Co-emulsifier、Stabilizer for High Oil Phase Systems, suitable for the formulation needs of various B-terminal customers.
Overall, the Span series, as a class of low HLB, nonionic, partial oil phase sorbitan fatty acid ester emulsifiers, occupies an irreplaceable core position in many fields with its clear structural source, outstanding core advantages and a wide range of application scenarios.
Hubei Mingya New Material Technology Co., Ltd.
