Chemical Functional Definitions
Builders
- What is a builder and what it is use for?
- What do builders look like, and how do they work?
- An example of an alkali type builder: Carbonate
- An example of an ion exchange type builder: Zeolite A
- An example of a complex builder system: Polyacrylate - Zeolite
- More information about builders in laundry detergents
What is a builder and what it is use for?
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Builders are materials that can bind cations (mainly calcium, Ca2+, and magnesium Mg2+) contained in wash solutions, resulting in water softening.
Builders improve the quality of the water, hence letting the detergents work in a more efficient way. They soften water by binding free water hardness ions (magnesium, calcium). This prevents those particles to react with other detergent ingredients, which would cause them to work less efficiently or precipitate from solution (soap scum). They can form insoluble salts that become encrusted in the fabrics and deposit on solid surfaces inside the washing machine. In this way builders extend the life of the washing machine. Soil molecules are often bound to the fabric surface by calcium ion bridging; removal of hardness from the environment therefore helps stain removal. Sometimes more than one builder is used in a product, to create a builder system with improved cleaning performance.
Builders improve the quality of the water, hence letting the detergents work in a more efficient way. They soften water by binding free water hardness ions (magnesium, calcium). This prevents those particles to react with other detergent ingredients, which would cause them to work less efficiently or precipitate from solution (soap scum). They can form insoluble salts that become encrusted in the fabrics and deposit on solid surfaces inside the washing machine. In this way builders extend the life of the washing machine. Soil molecules are often bound to the fabric surface by calcium ion bridging; removal of hardness from the environment therefore helps stain removal. Sometimes more than one builder is used in a product, to create a builder system with improved cleaning performance.
What do builders look like, and how do they work?
There are different types of builders and sometimes more than one type of molecule is involved, in which case we have a builder system. Builders are STPP, Zeolites, Carbonate, Citrate, SKS6, Silicate and they have 3 jobs to perform:
STPP is the most effective builder available yet it is negatively perceived from an environmental stand point. Zeolite is more environmentally friendly yet it provides less efficiency. STPP are no longer used in our Western European laundry detergents since many years.
There are 3 types of builders:
Sequestrating builders like STPP and citrate. They are soluble builders and form soluble complexes with hardness.
Precipitating builders like carbonate and soap. They are soluble builders and form insoluble complexes with hardness
Ion exchanger builders like Zeolite and SKS-6. They are insoluble builders and form insoluble complexes with hardness
In laundry detergent they are used at a range of 20-40 % while in hard surface cleaner only at 1-3%.
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| 1. | Body soil like perspiration that needs neutralizing, |
| 2. | Help remove the calcium and magnesium salts found in hard water and this allows surfactant to get on with their job of cleaning, |
| 3. | Finally they help to remove particulate soils made up of clay, dirty and fatty lipid stain. |
STPP is the most effective builder available yet it is negatively perceived from an environmental stand point. Zeolite is more environmentally friendly yet it provides less efficiency. STPP are no longer used in our Western European laundry detergents since many years.
There are 3 types of builders:
Sequestrating builders like STPP and citrate. They are soluble builders and form soluble complexes with hardness.
Precipitating builders like carbonate and soap. They are soluble builders and form insoluble complexes with hardness
Ion exchanger builders like Zeolite and SKS-6. They are insoluble builders and form insoluble complexes with hardness
In laundry detergent they are used at a range of 20-40 % while in hard surface cleaner only at 1-3%.
An example of an alkali type builder: Sodium Carbonate
2CO3) improves cleaning performance by raising the pH of the wash solution. Under alkaline conditions, soils and fabrics become more negatively charged and thus there is more electrostatic repulsion between them. Soda ash also "builds" the wash solution by removing water hardness, which precipitate out in the form of insoluble calcium and magnesium salts. The use of precipitating builders by themselves has gone out of fashion because of the problems associated with the deposition of insoluble salts onto washing machine surfaces and also onto the fabrics, resulting in incrustation 
hence diminished cleaning performance.
hence diminished cleaning performance.
An example of an ion exchange type builder: Zeolite A
Zeolites are synthetic sodium aluminum silicates - or synthetic clays - that are used in detergents (among other applications) for their cation-exchanging capacity. Most modern laundry detergent powders and tablets that do not contain phosphate, contain zeolites. Zeolites replace the water hardness ions (Ca2+ and Mg2+) with Na+ ions. Zeolites, like clays, are insoluble in water and are present in the wash as finely dispersed crystals (with a diameter of ca. 4 microns).
Zeolite is a silicate mineral with a crystalline structure of linked tetrahedra, as shown below. Macroscopically, a zeolite particle consists of thousands of stacked layers. Na+ cations are loosely held inside the structure and are readily replaced with Ca2+ and/or Mg 2+ ions, which are held more tightly.
Zeolite A is a form of zeolite that is optimized for use in detergents, also known under the trade name of Sasil®. The level of Zeolite A used in laundry detergents typically ranges from 20 to 34%.
A newer version of zeolite is Zeolite P, which offers the advantages of stronger calcium binding and a larger surface area-to-weight ratio relative to Zeolite A.
Zeolite is a silicate mineral with a crystalline structure of linked tetrahedra
, as shown below. Macroscopically, a zeolite particle consists of thousands of stacked layers. Na+ cations are loosely held inside the structure and are readily replaced with Ca2+ and/or Mg 2+ ions, which are held more tightly.Zeolite A is a form of zeolite that is optimized for use in detergents, also known under the trade name of Sasil®. The level of Zeolite A used in laundry detergents typically ranges from 20 to 34%.
A newer version of zeolite is Zeolite P, which offers the advantages of stronger calcium binding and a larger surface area-to-weight ratio relative to Zeolite A.
Examples of complex builder systems: Polyacrylate + Zeolite
There are different types of builders and, as stated, sometimes more than one type of molecule is involved in the "builder system". In this section we focus on the Polycarboxylate - Zeolite type of association. Polycarboxylate (PAA) are water-soluble polymers that have a high capacity to adsorb divalent cations such as Ca2+ and Mg2+ from solid surfaces - the fabrics, in this case - and transport them through the wash solution. A necessary "partnering" ingredient is a cation exchanger, which accepts the cations from the builder, irreversibly binds them and in exchange releases cations (usually Na+) that will not negatively impact the performance of the detergent. A well known cation exchanger is Zeolite A or sodium aluminum silicate. The PAA-Zeolite A binary builder system is commonly used instead of sodium triphosphate in today's phosphate-free granular laundry detergents. Once PAA releases the bivalent cations to the ion exchanger, the builder is re-used. The PAA molecule thus functions as a shuttle for divalent cations between the fabric surface and the ion exchanger.
In addition to its capacity as a co-builder, PAA also has dispersing properties in aqueous solutions. All water-soluble polyanionic polymers are more or less effective as dispersants.
In addition to its capacity as a co-builder, PAA also has dispersing properties in aqueous solutions. All water-soluble polyanionic polymers are more or less effective as dispersants.
More information about builders in laundry detergents
- Anderson RL, Bishop WE and Campbell RL. 1985. A Review of the Environmental and Mammalian Toxicology of Nitrilotriacetic Acid. CRC Critical Reviews in Toxicology, 15: 1-102.
- De Oude NT (ed.). 1992. The Handbook of Environmental Chemistry. Vol. 3, Part F: Anthropogenic Compounds: Detergents. Springer-Verlag, New York. ISBN 0-387-53797-X.
- Dwyer MD, Yeoman S, Lester JN and Perry R. 1990. A Review of Proposed Non-Phosphate Detergent Builders, Utilization and Environmental Assessment. Environmental Toxicology, 11: 263-294.
- Hering JH and Morel FMM. 1988. Kinetics of Trace Metal Complexation: Role of Alkaline-Earth Metals. Environ. Sci. Technol. 22: 1469-1478.
- Madsen T, Buchardt Boyd H, Nylén D, Rathmann Pedersen A, GI Petersen and Simonsen F. 2001. Environmental Project # 615. Environmental and Health Assessment of Substances in Household Detergents and Cosmetic Detergent Products. Phosphates (p 95); Phosphonates (p 96); Citrate (p 103); zeolites (p 104); EDTA (p 105); NTA (p 108). Text available from the Danish EPA at (Danish EPA report on detergents).
- Smulders E (ed.). 2002. Laundry Detergents. Wiley-VCH Verlag GmbH, Weinheim, Germany. ISBN 3-527-30520-3.
- Sillanpää M. 1997. Environmental Fate of EDTA and DTPA. In: Reviews of Environmental Contamination and Toxicology 152: 85-111.
