Tween™ 20

In simple terms, Tweens are ethoxylated Spans. A polyethoxylated monoester of 3,6-sorbitan can be represented as:

Figure 2: Chemical structure - polyethoxylated monoester

R is the alkyl group of a fatty acid and (X+Y+Z) is the total number of moles of ethylene oxide.

Tweens are hydrophilic in nature and are soluble or dispersible in water and dilute solutions of electrolytes. The solubility of Tweens in aqueous solutions increases with the degree of ethoxylation. For a fixed degree of ethoxylation, aqueous solubility decreases as the number of ester groupings increases. For a fixed degree of
ethoxylation and esterification, aqueous solubility decreases as the molecular weight of the fatty acid increases.

The Tween™ Series of surfactants are polyoxyethylene derivatives of the Span™ Series products. Tween™ surfactants are hydrophilic, generally soluble or dispersible in water, and soluble in varying degrees inorganic liquids. They are used for oil-in-water (O/W) emulsification, dispersion or solubilization of oils, and wetting. Frequently, Tween™ surfactants are combined with similarly numbered Span™ surfactants to promote emulsion stability. These products are widely used in personal care, fiber finish, HI&I cleaning, crop protection, paints & coatings, adhesives and other industrial applications.

Sorbitan esters and their ethoxylates

Croda's unique expertise in ester technology and continuing commitment to customers has established the company as a world-leader in the supply of sorbitan esters and derivatives for an array of applications. A unique understanding of the highly complex properties and functions of sorbitan esters has been developed to ensure customer developments are cutting edge in today's highly competitive environment.

The Spans and Tweens are a range of mild nonionic surfactants providing formulating benefits in a number of Home Care applications. Croda's Span and Tween materials have long-standing food and pharmacopeia approval with a safe history of use.

As nonionics, Spans and Tweens offer many advantages over ionic surfactants including increased stability, formulating flexibility and wider compatibility. They are stable in mild acids, alkalis and electrolytes and do not react with ionic ingredients or actives. By combining Spans and Tweens at different ratios, formulators are able to produce systems with a wide HLB range to emulsify most oils and waxes. Certain Spans and Tweens are also highly effective solubilisers, dispersing agents and wetting aids.

• Nonionic emulsifiers and co-emulsifiers
• Solubilisers
• Dispersants
• Wetting agents
• Stable over a wide pH range
• Electrolyte tolerant

Tween products can provide quick and easy removal of oily stains from wipes. A growing area in household cleaning sees use once non woven wipes giving quick cleaning  options to those with little time. Tween 20, 21, 80 and 85 are useful in creating on action emulsions with stains helping cleaning efficiency and maximum stain removal. Tween 20 is also classed as a mildness additive and is suitable for use in wipes where skin contact is prolonged.

The Tween range act as extremely versatile solubilisers for all types of fragrance and are excellent oil in water emulsifiers. Tween 20 has a very pale coloration and low odor, which is beneficial in the formulation of colorless systems.

Span and Tween surfactants find widespread use in a diverse range of household consumer products and are useful as emulsifers, solubilisers, wettinq aqents and dispersants.

Polishes

Spans and Tweens are key emulsifying agents for a number of applications. By using combinations of Spans with their corresponding Tweens it is possible to prepare a variety of oil in water and water in oil emulsion systems.

Air Care

Tweens are extremely versatile as solubilisers for all types of fragrances and perfumes used in air fresheners and other household products. Tween 20 and Tween 80 have high HLB values and are of particular interest when solubilising volatile components. Tween 20, a fully saturated ester, is most commonly used in this application due to its low odor. Typical inclusion levels are 1:1 Tween to fragrance, depending on the formulations and fragrance to be solubilised. Tweens are recommended for odor neutralisers and solvent based degreasers.

Wipes

For quick and easy removal of oily stains, Tweens can be incorporated into wipe formulations and added to non-woven substrates. Tween 20, 80 and 85 are helpful in creating on action emulsions with oily fats helping cleaning efficiency. Tween 20 has the additional benefit of being a mildness additive and is suitable for use in wet wipes where contact with the wipe may be prolonged.

S = Soluble, clear
D = Insoluble, self-dispersing or self-emulsifying; on standing, separates into distinct phases
I = Insoluble, gross separation into distinct phases

Tweens are considered to be inherently biodegradable and would not be expected to persist indefinitely in the environment.