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New phosphorus-free builder – modified sodium disilicate (MDS)

Detergents are widely used daily chemical products. According to relevant data, my country’s annual output of laundry detergents has reached 4 million tons, 90% of which are phosphorus-containing laundry detergents that use sodium tripolyphosphate (STPP) as a builder. Laundry powder is the main source of phosphorus pollution in rivers and lakes. Controlling or switching to phosphorus-free laundry detergent is an important way to solve the phosphorus load of domestic sewage. As people’s awareness of the ecological environment increases, and as the production cost of STPP further rises, it is urgent to develop phosphorus-free builders that can fully replace STPP.

The most commonly used phosphorus-free builder is 4A zeolite. Although it was developed earlier, 4A zeolite has irreparable defects in performance and can only partially replace STPP.

①The reason why this substance can soften water is that the diameter of the pores of 4A zeolite is exactly the diameter of calcium ions in the water, so it adsorbs it, but has little binding to magnesium ions in the water, so its water softening performance is average;

② Due to the 4A zeolite’s The pH value is neutral, which cannot meet the alkalinity required by detergents. Some alkali must be added when using it, which increases the production cost of detergents;

③4A zeolite is a solid substance insoluble in water, without suspension or dispersion performance, so the laundry detergent produced with it will produce deposits during washing, causing secondary pollution to the fabric or difficulty in rinsing. In order to alleviate this shortcoming, dispersants such as sodium citrate have to be added, which increases production costs.

④ It has no obvious synergistic effect with surfactants and must be used with other auxiliary additives to form a binary, ternary or multi-agent system. In addition, the 4A zeolite in the discharged washing wastewater will form new deposits on different ground surfaces, which will also be a burden to the ecological environment.

A new generation of phosphorus-free detergent builder, layered crystalline sodium disilicate (referred to as layer silicon), simultaneously fulfills the three major functions of a detergent builder, namely softening water and providing necessary alkalinity for laundry detergent with a stable pH value, showing good performance. The ability to resist re-sedimentation. It is currently a good alternative to sodium tripolyphosphate. In the past ten years, professionals at home and abroad have conducted extensive research on it, and some companies have also carried out mass trial production. However, many things could still be improved in practical applications. For example, the layer of silicon is difficult to be used in the pre-batching process; the layer of silicon dissolves in water or is prone to transformation at higher temperatures; poor water solubility affects the washing effect; high energy consumption, high production costs, and low profits are difficult to accept in the laundry detergent industry. ​

Combining new domestic and foreign research results and production practice experience, our company has comprehensively improved the existing sodium disilicate products and successfully developed a new phosphorus-free additive, “Modified Sodium Disilicate (MDS).” This product has good calcium and magnesium exchange capacity, good water solubility and flexible use – it can be directly used in the pre-batching process of high-tower powder spraying process or in post-batching production. It has good water immersion stability and is compatible with surfactants and polymers. The compatibility and synergy are good and the price is low, which not only protects the environment but also meets the requirements of enterprises to reduce production costs. The modified sodium disilicate (MDS) produced by our company has the following characteristics:​

MDS has a strong ability to soften water.

MDS has better water softening performance than ordinary silicate and 4A zeolite. For example, the ability of sodium silicate to bind calcium (calculated as CaCO3) and magnesium (calculated as MgCO3) is 100.2 mg/g and 94.3 mg/g respectively, 4A zeolite is 301.4 mg/g and 77 mg/g, and 4A zeolite only binds calcium. It has good softening ability and little binding ability to magnesium, while MDS has an outstanding ability to bind calcium and magnesium higher than 360 mg/g and 380 mg/g, respectively. MDS has a strong ability to bind calcium and magnesium ions and soften water thoroughly.

MDS can stably provide the alkalinity required during the washing process.

MDS can both soften water and stabilize alkalinity. When 1g of MDS is contained in each liter of water, the pH value of the aqueous solution can reach 9.5 to 12, depending on the temperature and other substances in the detergent formula. This means a small amount of raw material can be used to achieve maximum effectiveness. ​

MDS has excellent decontamination ability and anti-sedimentation ability.

Compared with other builders (such as sodium tripolyphosphate, 4A zeolite, sodium metasilicate), MDS can save 20% of the active combination in medium hard water. Different from ordinary silicates and 4A zeolites, sodium disilicate modified with special organic polymer active substances has a synergistic effect on surfactants. Its decontamination index is 1.46, which is close to sodium tripolyphosphate (decontamination index 1.5) and 4A zeolite (decontamination index 1.31). ​

MDS can effectively change fabric fibers’ hardening and hardening phenomenon, has a good suspension effect on dirt particles and oil stains, and can exert good anti-settling ability. ​

In addition, MDS has a significant effect on stabilizing the bleach in laundry detergent. It can not only improve the storage life of bleach, but also has a good synergistic effect and has a good adsorption effect on surfactants. ​


TRUNNANO is a supplier of sodium disilicate with over 12 years experience in nano-building energy conservation and nanotechnology development. It accepts payment via Credit Card, T/T, West Union and Paypal. Trunnano will ship the goods to customers overseas through FedEx, DHL, by air, or by sea. If you are looking for high-quality sodium disilicate please feel free to contact us and send an inquiry.