Low-Hygroscopic MGDA Salt via Controlled Crystallization
Solution Overview
Problem
Hygroscopic granules and powders of methylglycine diacetate (MGDA) and its alkali metal salts pose challenges in laundry and dishwashing detergents, leading to lump formation, reaction deactivation, and yellowing, which are undesirable for product stability and consumer acceptance.
Innovation Solution
A process involving a 40-60% aqueous solution of MGDA salt, heating, adding solid salt, allowing crystallization, and filtering to produce solid MGDA or its alkali metal salts with low hygroscopicity, resulting in powders or granules with controlled particle sizes and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If MGDA salts are produced as granules or powders, then shipping and storage are economical due to high active ingredient content, but the products become hygroscopic leading to lump formation and product degradation
Solution Approach 1:
The invention changes the physical and chemical parameters of the MGDA salt production process, specifically controlling crystallization conditions and water content to produce a modified solid form that maintains high active ingredient content while reducing hygroscopicity. The process parameters including temperature, concentration, and crystallization rate are optimized to achieve the desired product properties.
Solution Approach 2:
The invention utilizes phase transition during the crystallization process to transform MGDA from a hygroscopic solid form to a modified crystalline structure with reduced water affinity. The controlled crystallization from aqueous solution produces a stable solid phase that inherently resists moisture absorption, thereby maintaining product stability while preserving high active ingredient content.
2Ease of operation
If water is present in MGDA powders, then the material is easier to handle in liquid formulations, but it causes lump formation and deactivates formulation components
Solution Approach 1:
The invention extracts or removes the harmful water component from the MGDA powder structure through controlled crystallization and drying processes. The resulting product maintains the necessary solubility and handling properties for liquid formulations while having sufficiently low water content to prevent lump formation and component deactivation. This selective removal of water achieves the desired balance between operability and stability.
3Reliability
If MGDA salts are stored with percarbonate, then they provide enhanced cleaning performance, but they yellow when hygroscopic
Solution Approach 1:
The invention applies beforehand cushioning by pre-modifying the MGDA salt structure through controlled crystallization to reduce its hygroscopicity before storage with percarbonate. This preventive measure ensures that the MGDA salt maintains low moisture content during storage, thereby preventing the yellowing reaction that would otherwise occur when hygroscopic MGDA interacts with percarbonate. The cleaning performance is preserved while the harmful yellowing effect is prevented in advance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process yields MGDA salts with low hygroscopicity, enhanced stability towards percarbonates, and high purity, suitable for cleaners and automatic dishwashing detergents, ensuring consistent product performance and appearance.
Implementation Method 1
heating the resultant slurry until the salt (a) added in step (B) has dissolved at least partially
Implementation Method 2
allowing salt (a) to crystallize
Data Source
AI summary
A process for making solid methylglycine diacetate (MGDA) alkali metal salt (a) includes:(A) providing a 40 to 60% by weight aqueous solution of the MGDA salt having a temperature in the range of from 50 to 90° C.,(B) adding solid salt (a),(C) heating the resultant slurry until the salt (a) added in step (B) has dissolved at least partially,(D) allowing salt (a) to crystallize, and(E) removing crystalline salt (a) from the mother liquor.