Crystal Type III MGDA Salt Humidity Stability

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Solution Overview

Problem

Methyl glycine-N,N-diacetic acid and its salts are sensitive to humid conditions, leading to water absorption and loss of free-flowing properties in powders, making them unsuitable for dry applications like automatic dishwashing products, and high water content negatively impacts detergent formulations.

Innovation Solution

A new crystalline form of methyl glycine-N,N-diacetic acid trisodium salt, referred to as crystal type III, is developed through a heat treatment process that converts crystal type I into a form with improved stability and reduced water content, along with a process to convert it back to hydrated crystal type I for enhanced free-flowing properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If MGDA is isolated as an amorphous solid, then it is easy to obtain, but it absorbs water under humid conditions and loses free-flowing properties

Engineering Contradiction:
Improveease of isolationVSAvoidfree-flowing properties under humidity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by transforming MGDA from an amorphous solid state to a crystalline solid state through controlled crystallization processes. This phase transition fundamentally alters the material's properties, making it resistant to water absorption while maintaining ease of manufacture through optimized crystallization conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes phase transitions by converting MGDA from amorphous to crystalline form. This phase change is achieved through controlled cooling, evaporation, or other crystallization methods that promote ordered molecular arrangement, thereby eliminating the hygroscopic nature of amorphous MGDA while preserving its chelating functionality.

Inventive Principle:
Principle #36Phase transitions

2Stability of the object's composition

If MGDA is crystallized to improve free-flowing properties, then storage stability improves, but water content must be controlled to maintain formulation stability

Engineering Contradiction:
Improvestorage stabilityVSAvoidwater content impact on formulations
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-controlling the water content and crystalline structure of MGDA before it is incorporated into detergent formulations. Through controlled crystallization and drying processes, the material is prepared in advance with optimal properties, preventing subsequent formulation instability and eliminating the need for additional protective measures.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If crystal type I is used, then it shows good free-flowing properties, but it requires additional disintegrants in formulations

Engineering Contradiction:
Improvefree-flowing propertiesVSAvoidformulation complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies universality by developing a crystalline MGDA form that performs multiple functions simultaneously: it maintains excellent free-flowing properties for easy handling while also providing inherent disintegrant functionality that eliminates the need for separate disintegrant additives. This multi-functional crystal structure simplifies the overall formulation while maintaining operational ease.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 new crystal type III maintains better free-flowing properties under high humidity and reduces the need for additional disintegrants, offering higher active content and cost-effectiveness in formulations, while rehydrated crystal type I retains improved flowability.

Implementation Method 1

A new crystalline form of methyl glycine-N,N-diacetic acid trisodium salt, referred to as crystal type III, is developed through a heat treatment process that converts crystal type I

Methodology Applied
Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

a process to convert it back to hydrated crystal type I for enhanced free-flowing properties

Methodology Applied
Scientific EffectRehydration: Absorption (physical)

Data Source

PatentEP3649105B1Sodium methyl glycine-n,n-diacetic acid compound, process to prepare it and use thereof
Publication Date: 2021.09.01 AKZO NOBEL CHEMICALS INTERNATIONAL BV
  • EP3649105B1 patent drawingFigure 1
  • EP3649105B1 patent drawing

AI summary

The present invention relates to a methylglycine-N,N-diacetic acid trisodium salt in the form of a crystal, comprising a crystalline modification referred to as crystal type III characterized by the below reflections when analyzed with X-ray diffraction analysis using Cu Kα radiation. The invention furthermore relates to compositions containing the crystal type III salt, to a process to prepare it, to the use thereof and to the rehydrated crystal type I that can be obtained by contacting crystal type III with water. (Type III)