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Understanding Laundry Detergent

Laundry is one of the most mundane tasks in daily life. Among products used for washing clothes, laundry powder has long dominated the market. However, observant individuals may notice that the primary component of laundry detergent is non-ionic surfactants, which possess strong stain-removing capabilities and can penetrate deep into fabric fibers to clean more thoroughly.

The working principle of laundry detergent is similar to that of traditional laundry powder and soap, as the active ingredient in all of them is surfactants. The difference lies in the fact that traditional laundry powder and soap use anionic surfactants, primarily alkylbenzene sulfonate and sodium stearate, which are highly alkaline and can cause significant skin irritation and damage during use. In contrast, laundry detergents mostly utilize non-ionic surfactants, with a pH close to neutral, making them gentler on the skin. Additionally, they degrade faster in the natural environment compared to laundry powder, which is why they have become the new generation of cleaning agents.

The active ingredient in laundry detergent is primarily non-ionic surfactants. Their structure includes a hydrophilic end and a lipophilic end. The lipophilic end binds to stains, and through physical movements (such as hand scrubbing or machine agitation), the stains are separated from the fabric. Simultaneously, the surfactants reduce the surface tension of water, allowing it to reach the fabric surface and enabling the active ingredients to take effect.

1. National Standards for Laundry Detergent
National Standard of the People's Republic of China GB/T 26396-2011 "Safety Technical Specification for Cleaning Products"
Standard Drafting Units: China Research Institute of Daily Chemical Industry, China National Institute of Standardization, Guangzhou Blue Moon Industrial Co., Ltd., Xi'an Kaimi Co., Ltd., Beijing Green Umbrella Chemical Co., Ltd., Beijing Luowa Daily Chemicals Co., Ltd.

2. Industry Requirements
High-quality laundry detergents typically meet three main criteria: high concentration for reduced dosage; low viscosity for easy dissolution; and low foam for easy rinsing. This means the active ingredient content in the detergent should be high, as the cleaning power primarily depends on this content. Generally, a higher active ingredient content indicates more effective components. Industry regulations stipulate that the total active matter content should not be less than 15%. Products bearing the "Concentrated Detergent Mark" have even higher active matter content, usually reaching 30%. For user convenience, laundry detergents are specially formulated with adjusted viscosity to improve flowability, making them easy to pour, pre-treat, and dissolve. At the same time, foam control technology is employed to produce minimal foam that is easily rinsed, often requiring just one rinse to remove most of it.

3. Composition of Laundry Detergent
The main components of laundry detergent include surfactants, performance boosters, anti-redeposition agents, pH adjusters, chelating dispersants, inorganic salts, functional additives, solvents, co-solvents, defoamers, preservatives, and fragrances/colorants.
1. Surfactants: These are the primary active ingredients for removing dirt, usually composed of anionic and nonionic surfactants. Anionic surfactants include sodium lauryl ether sulfate (AES), while nonionic surfactants include fatty alcohol polyoxyethylene ether (AEO9). These components work by separating stains from fabric through their hydrophilic and lipophilic ends.
2. Performance Boosters: Include enzyme preparations such as proteases, lipases, and cellulases to enhance cleaning effectiveness.
3. Anti-Redeposition Agents: Such as polyvinylpyrrolidone, which prevent dirt from re-depositing onto clothes.
4. pH Adjusters: Such as sodium hydroxide, used to adjust the acidity or alkalinity of the detergent.
5. Chelating Dispersants: Such as sodium citrate, which help remove metal ions and dirt from water.
6. Inorganic Salts: Such as sodium chloride for adjusting detergent viscosity; sodium sulfate and calcium chloride are used to protect enzyme preparations.
7. Functional Additives: Including color transfer inhibitors, antibacterial plant extracts, etc., to add functionality to the detergent.
8. Solvents and Co-solvents: Such as ethanol and propylene glycol, which help dissolve and disperse dirt.
9. Defoamers: Control the amount of foam in the detergent for easier rinsing.
10. Preservatives: Such as Kathon and Bronopol, to extend shelf life.

11. Fragrances and Colorants: Provide a pleasant appearance and scent to the detergent.

4. Classification of Laundry Detergents
Products on the market are primarily of the standard type, focusing solely on cleaning. Building on this, some detergents add antibacterial agents for enhanced germ-fighting effects, while others are specifically targeted, such as for infants and toddlers or delicate fabrics like underwear.

5. Analysis Examples of Laundry Detergents
1. Blue Moon Deep Clean Care Laundry Detergent --- Standard Type
Main Ingredients: Surfactants, enzyme preparations, stabilizers, viscosity regulators, fluorescent whitening agent CBS, preservatives, colorants, natural fresh fragrance.
2. Liby Natural Tea Seed Antibacterial Laundry Detergent --- Antibacterial Type
Main Ingredients: Tea seed extract, surfactants, anti-redeposition agents, enzyme preparations, fragrance, preservatives, colorants.
*Under laboratory conditions, the bacteria removal rate is as high as 99.9%, tested against Staphylococcus aureus and Moraxella osloensis.
3. Power 28 Special Care Laundry Detergent for Pregnancy & Infants --- Targeted Type
Main Ingredients: Polyamine-based bactericidal and anti-mite agent, surfactants, water softener, anti-redeposition agents, methylisothiazolinone, methylchloroisothiazolinone, fragrance. Effective ingredient for antibacterial and anti-mite action: Dodecyl dipropylenetriamine.
*Under test conditions, the removal rate for Staphylococcus aureus reaches 99.99%.
For the above three products, the listed main ingredients only indicate the type of substance used, without specific details. Essentially, this discloses very little information.

6. Why Laundry Detergents Do Not Have Ingredient Lists
1. Ingredient lists are not mandatory for laundry detergents.
Many cleaning products, such as shampoo and body wash, require detailed ingredient labeling because they come into direct contact with human skin, ensuring consumers are informed about safety and health. However, laundry detergent does not directly contact the consumer's skin, posing a much lower health risk compared to personal care items. Furthermore, laundry detergents are manufactured under standardized processes and quality inspections, generally making them safe and harmless. Therefore, there is no mandatory regulation for laundry detergents to disclose their ingredient lists.
2. Manufacturers are reluctant to disclose trade secrets.
From a manufacturer's perspective, an ingredient list would expose the product's formula and production process, making it easier for competitors to imitate or copy the product and potentially limiting the manufacturer's innovation capabilities. Additionally, manufacturers avoid overly public ingredient lists because, in reality, many consumers base their purchases primarily on brand and price per unit. Thus, the ingredient list is not a key factor determining a product's popularity.
3. Insufficient and reasonable regulatory measures.
A lack of effective supervision is another reason why laundry detergents do not disclose ingredient lists. Regulations governing the production and sale of cleaning products do not guarantee that every detergent must include an ingredient list. Moreover, even if an ingredient list is provided, it may not be accurate or comprehensive. Some unscrupulous businesses may use false labeling or printing methods to conceal or substitute certain ingredients to evade regulation. Coupled with quality issues among practitioners, public ingredient lists cannot completely prevent product authenticity problems. 

7. Focus Points & Insights
1. Regarding Antibacterial Laundry Detergents
According to industry standards, "antibacterial" detergents must achieve a sterilization rate of ≥90% against specified test bacteria using defined methods; "bacteriostatic" detergents must achieve a rate of ≥50%. The term "bacteria removal" is not clearly defined in the standards; it is a relatively vague concept. In practice, it usually refers to the ability to remove 99% of bacteria through rinsing or washing under specific experimental conditions. Antibacterial and bacteriostatic actions target killing bacteria, whereas bacteria removal refers to washing bacteria away from the attached surface—a subtle but important difference.
2. Regarding Natural Extracts
The pursuit of green and natural products has led to the widespread use of extracts in detergents, such as common ones like Centella Asiatica extract, Chamomile extract, and Scutellaria Baicalensis root extract. However, these extracts are generally present in trace amounts, making it difficult to evaluate their actual efficacy.
3. Regarding Fluorescent Whitening Agent CBS
The addition of "fluorescent whitening agents" to laundry detergents and powders can be considered an industry "open secret." The price difference between fluorescent whitening agents and their substitutes can be as high as fivefold.
Fluorescent whitening agents are dyes that can mask stains to achieve a whitening and brightening effect. However, as fluorescent whitening agents accumulate over time, white clothes may turn increasingly yellow, and colored clothes may become duller.
According to Chinese regulations, fluorescent whitening agents in daily chemical products can only be used in items that do not directly contact the human body, such as laundry powder and liquid detergent, and only in trace amounts. The industry standard "Fluorescent Whitening Agents for Detergents," effective from September 1, 2008, stipulates that clothing detergents may appropriately use two types of fluorescent whitening agents: distyrylbiphenyl and bis(triazinylamino)stilbene. CBS belongs to the distyrylbiphenyl class.
4. Regarding Enzyme Preparations

1. Amylase: An enzyme preparation capable of hydrolyzing starch. Starch can easily adhere to fabric fibers, forming stubborn stains. Using laundry detergent containing amylase can effectively remove such stains without damaging clothes.

2. Protease: Can break down proteins, effectively removing hard-to-clean stains like bloodstains and protein-based stains.

3. Synthetic Caprolactamase: An enzyme preparation capable of decomposing fatty acid amides. Stubborn stains like grease often require synthetic caprolactamase for removal.
   The types and varieties of enzyme preparations may differ across laundry detergent brands. It is recommended to choose a detergent based on individual cleaning needs. Also, clothes should be sorted before washing, and different washing methods selected according to the type of stain.

5. Regarding Methylisothiazolinone and Methylchloroisothiazolinone
More commonly known as Kathon, this generally refers to isothiazolinones, a type of biocide. It is a brownish-yellow transparent liquid primarily composed of Methylchloroisothiazolinone (CIT) and Methylisothiazolinone (MIT) in a ratio of 1:3. Isothiazolinones act as biocides by breaking the bonds of bacterial and algal proteins. Upon contact with microorganisms, they rapidly and irreversibly inhibit growth, leading to cell death. Thus, they are highly effective at inhibiting and killing common bacteria, fungi, and algae.
Isothiazolinone biocides have a heterocyclic structure. Their bactericidal principle mainly relies on the active part of the heterocycle destroying the DNA molecules within bacterial cells, rendering the bacteria inactive. They offer advantages such as strong antibacterial capability, low application dosage, good compatibility, and low toxicity. They are effective against a wide range of bacteria and fungi, are efficient, have good compatibility, a broad pH application range, and are biodegradable. They feature high biocidal efficiency, good degradability, leave no residue, are safe to handle, have good compatibility, strong stability, and low usage costs. They are miscible with chlorine and most anionic, cationic, and nonionic surfactants. At high doses, isothiazolinones show significant effectiveness in removing biological slime. Isothiazolinones are broad-spectrum, efficient, low-toxicity, non-oxidizing biocides.
When used as industrial biocides and mildew preventatives, the concentration of isothiazolinones is typically 0.05-0.4%.
Isothiazolinones are corrosive and can irritate the skin and eyes. Protective goggles and rubber gloves should be worn during handling. In case of contact with skin or eyes, rinse immediately with plenty of water.
6. Regarding "More Foam Means Higher Quality Detergent"
Not necessarily.
The amount of foam in a detergent does not directly determine its cleaning effectiveness. Foam is generated when surfactants in the detergent are agitated in water. (Mechanism of foam formation: Foam is the dispersion of air in a liquid. The active molecules or ions of the detergent adsorb at the air-solution interface, forming a thin film. The bubble walls form a robust film that is not easy to break or merge.) Foam can selectively adsorb dirt, especially solid dirt particles, which aids in cleaning. However, excessive foam or foam that persists is disadvantageous for washing various items, especially in washing machines where high-foam detergents are undesirable. In such cases, foam inhibitors are needed.
7. Regarding "Higher Viscosity Means Higher Quality Detergent"
The viscosity of a detergent is not necessarily linked to its cleaning effectiveness. The viscosity is primarily influenced by thickeners, which do not contribute to cleaning during the washing process. The cleaning power of a detergent mainly depends on its active ingredient content, i.e., the total active matter. Higher total active matter content means stronger cleaning power.
Furthermore, the viscosity of a detergent is also affected by temperature. At lower temperatures, viscosity increases, while at higher temperatures, it decreases. Therefore, viscosity alone is not a reliable standard for measuring a detergent's cleaning effectiveness.