Anionic surfactants are the original workhorse ingredients for the formulator. Familiar benefits such as wetting, foaming, surface tension reduction, detergency, dispersancy and excellent rinseability make our anionic surfactants a cost-effective choice to enhance formulation performance in numerous applications and end markets.
Exceptional acid and base stability, hard water tolerance and high temperature stability enable our anionic surfactants to deliver outstanding results in the harshest environments where other classes of surfactant struggle to perform.
Whoever said oil and water can’t mix had perhaps never heard of surfactants. A surfactant or a surface-active agent is a compound which lowers the surface tension at the interface of two liquids, a liquid and a gas or a liquid and a solid. It has an amphiphilic molecular structure which means that the molecule is water-loving (hydrophilic) at one end and fat-loving (lipophilic) at the other. The surfactant molecules align themselves such that their hydrophilic groups (heads) are in the water phase whereas the lipophilic end (tails) extend out into the oil or gas (usually air) phase. Surfactants are classified as follows based on the charge of the head group.
Anionic Surfactants:
The head group has a negative charge
Cationic Surfactants:
The head group has a positive charge
Amphoteric Surfactants:
The head group may simultaneously carry both anionic and cationic hydrophilic groups. Cations or anions are formed depending on ambient conditions such as pH.
Non-ionic Surfactants:
The head group carries no charge
A surfactant is a key ingredient in many cosmetics formulations. It may be used as a cleanser, emulsifier, dispersant, penetrator or thickener. Surfactants may also be added as wetting, foaming or solubilizing agents to various products.
Surfactants are an essential part of all cleansing formulations. Dirt can bind to skin and hair through natural skin oils or oily contaminants picked up from the environment. Surfactants combine oil and water to lift the contaminants off the surface which can then be washed away with water. The choice of a suitable surfactant depends on the preferred chemistry, method of delivery and desired user experience.
Wetting is the ability of a liquid to spread on a solid surface. Products with poor wetting properties tend to ball up on the surface. Surfactants also act as wetting agents, making the product easier to spread while also helping lift up oil from the surface for removal. Surfactants are incorporated as wetting agents in the formulation of creams and lotions.
Bubbles are formed when air is incorporated into a liquid as a result of working the product on the skin or hair. A small amount of surfactant, added to a product, reduces surface tension between the liquid and air phases thereby reducing the work needed to generate foam. The surfactant also increases the stability of the foam by inhibiting coalescence of bubbles. Although foaming does not contribute to dirt removal, it is an important part of a pleasing user experience.
Creams and lotions are formulated to deliver beneficial lipid (oily) materials to skin or hair. The lipid material is combined with water and other ingredients to formulate an easy-to-apply product. Surfactants are used as emulsifiers to produce semi-stable oil-in-water (lotions) or water-in-oil emulsions (creams).
Harsh surfactants interact with proteins and lipids in the outermost layer of the skin, called the stratum corneum. They may cause this protective barrier to break down leading to redness, irritation, dryness, and itching. Anionic surfactants generally offer the best foaming and cleansing properties for cosmetic applications but they are also the harshest towards human skin. Sanyo’s anionic surfactants offer reduced irritation to the skin and eyes than conventional products because they contain less sodium lauryl sulfate due to narrow distribution of the number of EO-adduct moles developed by using Sanyo's original Narrow Range Ethoxylation.
Narrow Range Ethoxylation can obtain alkylene oxide adducts having a narrow distribution of the number of alkylene oxide adduct moles. Sanyo discovered an effective catalyst for narrow range ethoxylation to develop this technique.
Foams are generally easier to generate and maintain under alkaline conditions. As the pH is lowered, the foam forming potential of surfactants is reduced. Sanyo surfactants show good foaming properties even in a weakly acidic medium. The range of products includes grades that generate stable, fine, rich and soft foams suited to various applications. Sanyo provide a wide range of foams according to your request.
Sanyo surfactants are easily bio-degradable which helps cosmetics manufacturers formulate products that are eco-friendly and sustainable.
The figure below compares the bio-degradability of Sanyo’s anionic surfactant BEAULIGHT LCA-30D to the conventional surfactant lauryl ether sulfate.
Sanyo surfactants offer the following additional benefits:
Low odor
Prevent excessive degreasing
Excellent solubility & detergency
Derived from natural higher alcohols
Compatible with other surfactants
Available as non-neutralized products
Compliance with safety and health regulations
Visit our application pages to learn more about Sanyo Chemical products.
A surfactant is a key ingredient in many cosmetics formulations. It may be used as a cleanser, emulsifier, dispersant, penetrator or thickener. Surfactants may also be added as wetting, foaming or solubilizing agents to various products.Surfactants are an essential part of all cleansing formulations. Dirt can bind to skin and hair through natural skin oils or oily contaminants picked up from the environment. Surfactants combine oil and water to lift the contaminants off the surface which can then be washed away with water. The choice of a suitable surfactant depends on the preferred chemistry, method of delivery and desired user experience.Wetting is the ability of a liquid to spread on a solid surface. Products with poor wetting properties tend to ball up on the surface. Surfactants also act as wetting agents, making the product easier to spread while also helping lift up oil from the surface for removal. Surfactants are incorporated as wetting agents in the formulation of creams and lotions.Bubbles are formed when air is incorporated into a liquid as a result of working the product on the skin or hair. A small amount of surfactant, added to a product, reduces surface tension between the liquid and air phases thereby reducing the work needed to generate foam. The surfactant also increases the stability of the foam by inhibiting coalescence of bubbles. Although foaming does not contribute to dirt removal, it is an important part of a pleasing user experience.Creams and lotions are formulated to deliver beneficial lipid (oily) materials to skin or hair. The lipid material is combined with water and other ingredients to formulate an easy-to-apply product. Surfactants are used as emulsifiers to produce semi-stable oil-in-water (lotions) or water-in-oil emulsions (creams). Sanyo Chemical offers a wide range of surfactants to meet the diverse requirements of various types of cosmetic formulations. The range includes cationic, anionic, amphoteric and non-ionic surfactants suitable for all major cosmetic applications. Sanyo surfactants offer the following benefits:Harsh surfactants interact with proteins and lipids in the outermost layer of the skin, called the stratum corneum. They may cause this protective barrier to break down leading to redness, irritation, dryness, and itching. Anionic surfactants generally offer the best foaming and cleansing properties for cosmetic applications but they are also the harshest towards human skin. Sanyo’s anionic surfactants offer reduced irritation to the skin and eyes than conventional products because they contain less sodium lauryl sulfate due to narrow distribution of the number of EO-adduct moles developed by using Sanyo's original Narrow Range Ethoxylation.Narrow Range Ethoxylation can obtain alkylene oxide adducts having a narrow distribution of the number of alkylene oxide adduct moles. Sanyo discovered an effective catalyst for narrow range ethoxylation to develop this technique.Foams are generally easier to generate and maintain under alkaline conditions. As the pH is lowered, the foam forming potential of surfactants is reduced. Sanyo surfactants show good foaming properties even in a weakly acidic medium. The range of products includes grades that generate stable, fine, rich and soft foams suited to various applications. Sanyo provide a wide range of foams according to your request.Sanyo surfactants are easily bio-degradable which helps cosmetics manufacturers formulate products that are eco-friendly and sustainable.The figure below compares the bio-degradability of Sanyo’s anionic surfactant BEAULIGHT LCA-30D to the conventional surfactant lauryl ether sulfate.Sanyo surfactants offer the following additional benefits:Visit our application pages to learn more about Sanyo Chemical products.
Surfactants are one of many different compounds that make up a detergent. They are added to remove dirt from skin, clothes and household articles particularly in kitchens and bathrooms. They are also used extensively in industry. The term surfactant comes from the words surface active agent.
Figure 1 Surfactants aid the effective washing of dirty rugby kit using low
temperature wash cycles, resulting in environmental benefits.
By kind permission of Stephen Garnett/Wharfedale RUFC.
Surfactants function by breaking down the interface between water and oils and/or dirt. They also hold these oils and dirt in suspension, and so allow their removal. They are able to act in this way because they contain both a hydrophilic (water loving) group, such as an acid anion, (-CO2- or SO3-) and a hydrophobic (water hating) group, such as an alkyl chain. Molecules of water tend to congregate near the former and molecules of the water-insoluble material congregate near the latter (Figure 2).
Soaps were the earliest surfactants and are obtained from fats which are known as glycerides because they are esters formed by the trihydric alcohol, propane-1,2,3-triol (glycerol), with long chain carboxylic acids (fatty acids). The glycerides are hydrolyzed by heating with sodium hydroxide solution to form soaps, the sodium salts of the acids, and propane-1,2,3-triol. The process is known as saponification.
Figure 2 Action of a surfactant.
The glycerides used to make surfactants contain saturated and unsaturated carboxylic acids which have an even number of carbon atoms, generally within the range 12-20, for example, octadecanoic acid (stearic acid), CH3(CH2)16CO2H.
Synthetic surfactants have one very important advantage over soaps. Because soaps form insoluble calcium and magnesium salts with the calcium and magnesium ions in hard water and in the clays which are present in dirt, much of the soap is wasted forming an insoluble scum. However, this is avoided when using a synthetic surfactant. For example, in the anionic surfactants, the carboxylate group in soap is replaced by a sulfonate or sulfate group as the hydrophilic component. The corresponding calcium and magnesium salts are more soluble in water than the calcium and magnesium salts of carboxylic acids.
Surfactants are classified based upon the nature of the hydrophilic "head-groups" as:
anionics cationics
nonionics
amphoterics
In these surfactants the hydrophilic group is negatively charged. They are the most widely used type of surfactants for laundering, dishwashing liquids and shampoos. They are particularly good at keeping the dirt, once dislodged, away from fabrics.
Four anionic surfactants are used:
a) alkylbenzene sulfonates
b) alkyl sulfates
c) alkyl ether sulfates
d) soaps
(a) Alkylbenzene sulfonates
The most common of the synthetic anionic surfactants are based on the straight chain alkylbenzene sulfonates. Benzene, in slight excess, is mixed with an alkene or chloroalkane in the presence of an acid catalyst, usually a solid zeolite (ion exchange), aluminium chloride (AlCl3) or hydrofluoric acid (HF), to produce an alkylbenzene (sometimes called detergent alkylate).
For example:
The alkylbenzene varies in average molecular mass, depending upon the starting materials and catalyst used and is often a mixture in which the length of the alkyl side chain varies between 10 and 14 carbon atoms. Historically these included branches in the side chains with the result that they biodegrade very slowly and lead to foaming in rivers and sewage plants. By law, in most countries today, the surfactant must have side chains which are not branched so they degrade more rapidly.
The alkylate is sulfonated using an air/sulfur trioxide mixture, and the resulting sulfonic acid is then neutralised with an aqueous solution of sodium hydroxide (often in situ), for example:
Straight chain alkenes for the above process can be produced from ethene using a Ziegler catalyst (triethyl aluminium). Triethyl aluminium reacts with ethene at ca 400 K and 100 atm to form aluminium alkyls, for example:
When heated in excess ethene, straight chain alkenes, with the double bond at the end of the chain (an a-alkene), are produced:
The mixture is then separated into fractions by distillation, the fraction of alkenes containing 10 to 14 carbon atoms being used to make the surfactants.
These are used together with other surfactants in powder and liquid laundry detergents such as Ariel, Daz, Persil and Surf.
(b) Alkyl sulfates
Many detergent products, particularly liquids, contain other synthetic anionic surfactants such as alkyl sulfates, esters of linear alcohols (C10-C18) and sulfuric acid. The alkyl sulfates are also used in personal care products such as toothpaste and are manufactured by treating the alcohol with sulfur trioxide. The product is then neutralised with aqueous sodium hydroxide solution to form a sodium alkyl sulfate:
The alcohols are either produced from carboxylic acids obtained from oils, obtained naturally, for example from palm kernel oil or coconut oil, or alternatively from long-chain alkenes, manufactured from ethene.
There are two processes for making the alcohols from ethene. As described above, aluminium triethyl reacts with ethene to produce compounds such as:
where a,b,c are even numbers from 2 to 12. Instead of heating with excess ethene to produce a-alkenes, the aluminium alkyl is treated with oxygen and then water to produce long chain alcohols:
Alternatively, a different process for making the alcohols from ethene is used, known as SHOP (Shell Higher Olefins Process). In the first stage, ethene is passed, under pressure of ca 100 atm, into a solvent (usually a diol, such as butane-1,4-diol) containing a nickel salt at 400 K. It yields a mixture of a-alkenes which are separated by fractional distillation. About 30% are in the range C10-C14.
These are reacted with carbon monoxide and hydrogen (hydroformylation) to yield straight-chain aldehydes, which on reduction form alcohols. For example:
It is possible to convert the other a-alkene fractions (C4-C10 and C14-C40) into the more desirable C10-C14 fraction.
(c) Alkyl ether sulfates
More widely used than simple alkyl sulfates are various types of sodium alkyl ether sulfates (SLES).
In the manfacture of SLES the primary alkyl alcohol (from a synthetic or natural source and typically a blend based around dodecanol) is first ethoxylated with 1 to 3 molar equivalents of epoxyethane (as described below for the manufacture of nonionic surfactants). The product is then sulfated using sulfur trioxide and neutralized with alkali to form the alkyl ether sulfate:
These materials are preferred by product formulators for many applications (dishwashing liquids, shower gels, shampoo, etc) because they are milder to the skin than alkyl sulfates. They also generate less foam which is an advantage in the formulation of laundry machine products.
(d) Soaps
Soaps are anionic detergents:
With these surfactants, the hydrophilic head is positively charged.
Although they are produced in much smaller quantities than the anionics, there are several types, each used for a specific purpose.
(a) Mono alkyl quaternary systems
The simplest quaternary system is the ammonium ion:
An alkyl quaternary nitrogen system has alkyl groups attached to the nitrogen atom. An example is:
They are used as fabric softeners with anionic surfactants, helping them to break down the interface between the dirt/stain and the water.
(b) Esterquats
The directly quaternised fatty acid surfactants described above have been replaced for laundry applications by more complicated structures in which there is an ester linkage between the alkyl chains and the quaternary head-group as these are more biodegradable and less toxic. They are known as esterquats.
An example is:
Esterquats give detergents their fabric softening qualities.
These surfactants do not bear an electrical charge and are often used together with anionic surfactants. An advantage is that they do not interact with calcium and magnesium ions in hard water.
They account for nearly 50% of surfactant production (excluding soap). The major group of nonionics are the ethoxylates made by condensing long chain alcohols with epoxyethane (ethylene oxide) to form ethers, for example:
The long-chain alcohol can come from either a synthetic or natural source.
Although they do not contain an ionic group as their hydrophilic component, hydrophilic properties are conferred on them by the presence of a number of oxygen atoms in one part of the molecule which are capable of forming hydrogen bonds with molecules of water.
As the temperature of the surfactant solution is increased the hydrogen bonds gradually break causing the surfactant to come out of solution. This is commonly referred to as the cloud point and is characteristic for each nonionic surfactant. Nonionics are more surface active and better emulsifiers than anionics at similar concentrations. They are less soluble than anionics in hot water and produce less foam. They are also more efficient in removing oily and organic dirt than anionics. Depending on the type of fibre, they can be active in cold solution and so are useful in countries which lack hot water supplies and in developed countries where there is a desire to lower the wash temperatures either to save energy or because of the type of fabric being washed. Nonionics are used in fabric washing detergents (both powders and liquids), in hard surface cleaners and in many industrial processes such as emulsion polymerization and agrochemical formulations.
Amphoteric (or zwitterionic) surfactants are so called because the head-group carries both a negative and positive charge. A range of methods is used to produce such materials, almost all of which contain a quaternary ammonium ion (a cation). The negatively charged group can be carboxylate, -CO2-, sulfate, -OSO3- or sulfonate, -SO3-. One such well-used class is the alkyl betaines which have a carboxyl group. A long-chain carboxylic acid reacts with a diamine to form a tertiary amine. On further reaction with sodium chloroethanoate, a quaternary salt is formed:
Betaines are neutral compounds with a cationic and an anionic group which are not adjacent to one another.
Amphoteric surfactants are very mild and are used in shampoos and other cosmetics. They are said to be pH balanced.
In this formulation there are seven surfactants, two anionic, three non-ionic and two soaps.
However, there are other ingredients, each with specific functions:
Bulking agents, such as sodium sulfate and water.
Some detergents need anti-caking agents, for example aluminium silicate, which keep the powder dry and free-flowing.
Builders, usually sodium aluminosilicates, a type of zeolite, remove calcium and magnesium ions and prevent the loss of surfactant through scum formation.
Stains can be bleached with oxidizing agents such as sodium perborate (NaBO3.4H2O) and sodium percarbonate (2Na2CO3.3H2O2) which react with hot water to form hydrogen peroxide which in turn reacts with the stain:
However bleach activators are needed for low temperature washes. Sodium perborate and sodium percarbonate do not liberate hydrogen peroxide in cool water. A compound is added to react with them to liberate a peroxycarboxylic acid, RCO3H, which oxidizes stains readily. The most commonly used activator is:
It is known by its trivial name, TAED, and reacts with the oxidizing agent to form peroxyethanoic acid:
IngredientFunction Sodium silicoaluminate Builder Sodium carbonate Buffering agent Sodium sulfate Bulking agent Sodium carbonate peroxide (sodium percarbonate) Oxidizing agent Sodium
dodecylbenzenesulfonate Surfactant Water Bulking agent C12-15 pareth-5 Surfactant Tetraacetyl ethylene diamine (TAED) Bleach activator Ceteareth-25 Surfactant Citric acid Builder Sodium silicate Builder Sodium acrylic acid/MA co-polymer Structurant C12-15 pareth-7 Surfactant Sodium stearate Surfactant Stearic acid Surfactant Tetrasodium etidronate Sequestrant Ethylenediaminetetra methylene phosphoric acid Ca/Na salt Sequestrant Maize starch Bulking agent Cellulose gum Anti-redeposition agent Parfum Fragrance Dimorpholinopyridazinone Optical brightener Sodium bentonite Softness extender Simethicone Antifoaming agent Sodium chloride Bulking agent Sodium polyacrylate Structurant Glyceryl stearate Emulsifier Sodium polyarylsulfonate Surfactant
Table 1 Ingredients of a detergent for washing clothes.
Other ingredients which can be added to a detergent include:
Buffering agents - to keep the pH at the appropriate value
Structurants - to give shape to the fabric being washed
Sequestrants - to react with free metal ions which might otherwise cause problems with appearance or scum formation
Optical brighteners - to make the fabrics look brighter and whiter
Antifoaming agents
Enzymes - to remove specific stains: proteases (to remove proteins), amylases (to remove starches), lipases (to remove fats)
Fragrance
Anti-redeposition agents - to prevent dirt being redeposited on fabrics
Skin conditioning agent - to help to keep the skin in good condition
Softness extender - to help keep the clothes 'soft'
Emulsifier - to help keep immiscible liquids as an emulsion
Colorant
Domestic automatic machine laundry liquids are formulated using blends of anionic, nonionic and soap surfactants and various other functional substances. Bleach systems are not compatible with the higher water temperature and cannot be used above ca 315 K.
For hand washing (used for delicate fabrics such as wool or silk), foam-stabilisers are included, to maintain foam. The customer equates the quantity of foam produced with the detergent cleansing action. For the quantity of foam produced the order is:
anionics > soap > nonionics > cationics
The products used in dishwashers are usually powders and contain builders (90-95%), a nonionic surfactant (1-5%), bleach agents with an activator and enzymes. They are formulated with sodium carbonate and sodium silicate to create a very alkaline environment that helps to denature (break down) the fats and proteins left on the used dishes and utensils.
These formulations contain between 13-40% of surfactants which are predominantly alkyl ether sulfates but also include nonionics and amphoterics (betaines).
These tend to be based on alkyl ether sulfates and usually contain small amounts of other surfactants (most typically amphoterics) which help protect the skin from irritation and also condition the hair.
These products are formulated using cationic surfactants (sometimes combined with small amounts of non-ionic surfactants). These are not cleansing products and the cationic surfactant is deposited onto the slightly negatively charged hair or cotton fibre surface, thus giving a lubrication benefit.
In Western Europe all surfactant components of domestic detergents must be biodegradable. This requirement resulted from the fact that the original alkylbenzene sulfonate anionics were based on branched alkenes and these proved resistant to degradation by bacteria at sewage treatment works causing many rivers to suffer from foam. There was also a fear that surfactants could be "recycled" into drinking water. Similar concerns were expressed about nonylphenol ethoxylates and so in the 1980s the industry moved to linear alkylbenzene sulfonates and alcohol ethoxylates as the major ingredients of their formulations. Effective sewage treatment ensures that detergent components which are part of household effluent water are not discharged untreated into rivers and water courses.
The development of compact powders and liquids and refillable packages is designed to reduce packaging waste.
Redesign of washing machines and laundry detergent products (including the addition of bleach activators and enzymes to ensure good stain removal at low temperatures) has resulted in energy savings by reducing water heating and using shorter wash cycles.
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