Background and overview[1]
Sodium tripolyphosphate is also known as sodium tripolyphosphate and pentasodium phosphate. White crystal. Molecular weight 367.86. Dissolved in water. There are two common types: anhydrate and hexahydrate. The anhydrate is stable and the hydrate is hygroscopic. The solubility of hexahydrate in water is less than that of anhydrous. It has good ability to complex metal ions and can complex with calcium, magnesium and iron metals to form soluble complexes. It has the functions of suspending, dispersing, peptizing and emulsifying oils and fats. Mainly used as an additive for synthetic detergents. Also used as water softener, pretanning agent, dyeing auxiliary, etc. It is prepared by using wet phosphoric acid as raw material, carrying out neutralization reaction with sodium hydroxide, and spray drying. Sodium tripolyphosphate acts as a softener, dispersant, and dyeing auxiliary. It is used as a softener in industrial water to reduce the content of calcium, magnesium, iron and other metal ions in industrial water and reduce the hardness of water; it is used as a dispersant in industrial configurations such as paint, kaolin, magnesium oxide and calcium carbonate, and is used to disperse drilling mud. agent. In addition, it can also be used as a detergent additive, food additive, and water-reducing agent for plaster and other molds.
Preparation[2-3]
1. Production of ultra-low type I sodium tripolyphosphate:
In industrial applications, sodium tripolyphosphate is generally formulated into an aqueous solution. When a large amount of sodium tripolyphosphate is poured into water, it will instantly agglomerate and form clumps, affecting subsequent use. Some existing technologies reduce the degree of agglomeration of sodium tripolyphosphate by changing the particle size of sodium tripolyphosphate and producing granular sodium tripolyphosphate. Others use pre-hydration to reduce the degree of caking by hydrating sodium tripolyphosphate hexahydrate in advance. The above methods have disadvantages to varying degrees. The strength of granular sodium tripolyphosphate particles is low, and it is difficult to ensure the effectiveness during long-term transportation and storage. At the same time, granular products increase transportation costs; products obtained by pre-hydration method are due to the presence of hexahydrate. , which reduces the solubility of the product and limits the scope of use. At the same time, the above methods only reduce the degree of sodium tripolyphosphate cluster agglomeration to varying degrees, but do not effectively solve this problem. The solubility of sodium tripolyphosphate is related to the ratio of its Type I and Type II. There are four ligands in the Type I structure and it has a strong affinity for water. Therefore, when dissolved under the same conditions, Type I quickly hydrates to form hexahydrate from the solution. It precipitates and the clusters become lumps, so that the higher the Type I content in the sodium tripolyphosphate product, the more serious the product will be. At present, the Type I content of industrialized products is mostly 15-60%, which leads to the problem of cluster hardening to varying degrees. Based on this, it is necessary to develop a production process for super Type I sodium tripolyphosphate with a Type I content of 0-3%. CN2018106 Hydroxy Acrylic Resin 79820.6 provides a production method for ultra-low type I sodium tripolyphosphate. It is achieved according to the following steps: (1) Neutralization reaction: under stirring conditions, add solid sodium carbonate and 85% phosphoric acid to a soda ash solution with a mass concentration of 30%-50%, and adjust the K value of the neutralization slurry Stop adding phosphoric acid at 2.8±0.1, heat the steam in the mixture to the system temperature of 40-50°C, and react for 45 minutes for later use; (2) Send the material obtained in step (1) into the regulating tank, and add trimerization under stirring conditions. Sodium phosphate aqueous solution, adjust the specific gravity of the slurry to 1.20± polyurethane raw material; 0.05, react for 25 minutes and filter to obtain a viscous slurry for later use; (3) Drying and dehydration: Send the obtained viscous slurry to the drying tower for atomization and dehydration at 130±10°C ; (4) Primary polymerization: Send the dried and dehydrated raw materials into the rotary polymerization furnace for primary polymerization reaction, the reaction time is 20-30min; (5) Secondary calcination: After primary polymerization, the materials are cooled to room temperature by the cooling drum, and then passed through the return The material drum is returned to the rotary polymerization furnace for calcination reaction. The calcination time is 30-40 minutes to obtain ultra-low type I sodium tripolyphosphate.
2. Utilize crude sodium pyrophosphate to produce sodium tripolyphosphate
The present invention provides a method for producing sodium tripolyphosphate by utilizing crude sodium pyrophosphate. Through experiments, the inventor successfully developed a method for producing sodium tripolyphosphate by adding crude sodium pyrophosphate in the form of liquid and crystal to the neutralization liquid of the traditional process after a refining process. This method can be realized using general-purpose equipment and not only It ensures various quality indicators of sodium tripolyphosphate and reduces the cost of raw materials for producing sodium tripolyphosphate. The technical solution adopted by the present invention is: a method for producing sodium tripolyphosphate using crude sodium pyrophosphate, which includes the following steps: (1) washing crude sodium pyrophosphate, dissolving sodium chloride in water, and filtering to obtain washing residue; ( 2) Perform a primary pressure filtration of the washing residue to obtain a filter cake and a primary filtrate; (3) Dissolve the filter cake, and add a removal agent to the solution to remove metal ions to obtain a removal solution; (4) Perform a second step on the removal solution Press filtration for the second time to obtain the secondary filtrate; (5) Add a decolorizing agent to the secondary filtrate to remove pigments, then add phosphoric acid to acidify it to accelerate dissolution, and finally add alkali to adjust the pH value to 7.5~8.5 to prepare a refined liquid. A part of the refined liquid is sent to the neutralization liquid preparation section in the sodium tripolyphosphate production process, and is mixed with phosphoric acid and liquid caustic soda to prepare a neutralization liquid as a raw material for the production of sodium tripolyphosphate;
(6) After cooling and crystallizing another part of the refined liquid, perform solid-liquid separation to obtain sodium pyrophosphate crystals and mother liquor;
(7) Send the obtained sodium pyrophosphate crystals to the neutralization liquid preparation section in the sodium tripolyphosphate production process to mix with phosphoric acid and liquid caustic soda to prepare a neutralization liquid as a raw material for the production of sodium tripolyphosphate.
Apply [4]
Low foaming washing powder is suitable for ordinary washing machines, automatic washing machine washing, and also suitable for manual scrubbing. It is a dual-purpose washing powder. The method of use for hand washing is the same as that of ordinary clothes washing powder. The amount of washing powder used, whether machine washing or hand washing, is generally controlled to be about 15 grams per kilogram of dry clothes. However, washing some woolen fabrics with ordinary laundry detergent will cause fabric fluff, shrinkage, and damage. CN201711184467.6 provides a sodium tripolyphosphate composite laundry detergent. Technical solution: a sodium tripolyphosphate composite laundry detergent, characterized in that: the sodium tripolyphosphate composite laundry detergent consists of the following components in parts by weight: 22-29 parts of sodium tripolyphosphate, fluorescent whitening agent 5-9 parts, sodium sulfate 10-13 parts, lauroyl monoethanolamine 7-12 parts, dimethicone 9-13 parts, the balance is water. Beneficial effects: The present invention is used for washing fine and soft fabrics, has good washing and decontamination effects, and is easy to wash and rinse during the washing process, saving time, effort and water.
Main reference materials
[1] Concise Dictionary of Fine Chemicals
[2] CN201810679820.6 A production method of ultra-low type I sodium tripolyphosphate
[3] CN201610688474.9 Method for producing sodium tripolyphosphate from crude sodium pyrophosphate
[4] CN201711184467.6 Sodium tripolyphosphate composite laundry detergent
