How to use fluorescent whitening agents in detergents (3.): Paste detergent
Paste (also called slurry) detergent has a certain application market because it has no flying dust, is easily soluble in water, is easy to use, has a fine paste, is mostly white or bright light color, and has aromatic or special fragrance. The composition of slurry detergent is similar to that of ordinary laundry detergent, but its moisture content is relatively high. The moisture content of the finished product should be about 40%, otherwise it is easy to separate. Sodium sulfate is usually not added to prevent crystallization. It is generally produced by sodium carboxymethylcellulose method or soap method.
(1) Sodium carboxymethyl cellulose method:
Use sodium carboxymethyl cellulose as a binder, and then add anionic or cationic surfactants as well as inorganic salts, flavors, fluorescent whitening agents, pigments, etc. to form a paste for washing agent formula.
Maintaining the stability of the paste is the key to production technology. This method uses sodium carboxymethylcellulose to form a network structure after being dissolved in water, which can firmly bind part of the water and coat a large amount of free water. The free water interacts with the inorganic The salt combination forms a network skeleton to stabilize the paste. At the same time, surfactants with washing effect form micelles at a certain concentration, and the micelles form when they encounter inorganic salts.
Micelle, the interior of the micelle can also absorb a large amount of water, reducing the free water in the entire slurry and making the paste more stable.
(2) Soap method:
Utilize the adsorption effect of sodium higher fatty acids in soap, and then add anionic or cationic surfactants as well as inorganic salts, flavors, fluorescent whitening agents, pigments, etc. to form a paste detergent formula.
This method uses the colloid effect of soap to absorb other fine substances, coat free water, produce agglomeration, and stabilize the paste. On the other hand, the micelles formed by surface active substances and inorganic salts can also reduce free water and have the same effect. It has the function of stabilizing the paste.
No matter which one of the above two production methods is used, the ingredients are generally added in the following order during preparation:
Anionic surfactant → water → sodium methylcellulose or soap → nonionic surfactant → soluble sodium silicate → sodium carbonate → sodium bicarbonate → (sodium tripolyphosphate) → ethanol → fluorescent whitening agent, fragrance →Pigments or fluorescent whitening agents→Sodium chloride
Adding a fluorescent whitening agent can significantly improve the appearance of the paste. The fluorescent whitening agent is generally added at the same time as the spices, or added after the spices are added, or the timing of addition is determined based on the solubility of the fluorescent whitening agent; for alkali resistance comparison Strong, well-soluble varieties, such as fluorescent whitening agent CBS, can be added at any stage.
(3) Application examples:
Application example 1:
Paste detergent. Formula (mass fraction):
Sodium alkyl benzene sulfonate 15%
Sodium alkyl benzene sulfonate 10%
CMC 1. 5% STPP 20%
Sodium carbonate 5%
Sodium chloride 4%
Sodium alkali (modulus 2.4, 30%) 5%
Ethanol 2%
Fluorescent whitening agent appropriate amount
Appropriate amount of fragrance
Deionized water balance
Preparation method:
Dissolve the active substances sodium alkyl benzene sulfonate and sodium alkyl sulfonate in deionized water, heat to 55~60°C with stirring, add fluorescent whitening agent and other other materials after dissolution, and add the essence after cooling Add, sodium chloride last. After stirring evenly, grind it with a colloid mill or use a homogenizer to homogenize and degas to make the paste fine and uniform. However, the mixing time should not be too long to avoid the paste becoming thinner or entraining air bubbles.
