Surface Modified Alumina with Phosphono Group for Low Viscosity
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Solution Overview
Problem
Citric acid modified aluminas become difficult to process due to increased viscosity at pH 8 and above, requiring the use of additional modifying agents like malonic acid, which can complicate ceramic production and introduce undesirable interactions.
Innovation Solution
A method involving the addition of a phosphono group containing modifier to alumina, which produces a surface modified alumina that is dispersible at pH 8 and above with low viscosity, while maintaining low modifier loadings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If citric acid is used to modify alumina to achieve dispersibility at pH 8 and above, then dispersibility is improved, but viscosity increases rapidly making processing difficult
Solution Approach 1:
The patent changes the chemical parameter of the modifying agent from citric acid to a phosphono group containing compound (such as phosphonic acid or phosphonate). This parameter change maintains the dispersibility function at pH 8 and above while fundamentally altering the interaction mechanism with alumina particles, thereby preventing the rapid viscosity increase that occurs with citric acid modification.
Solution Approach 2:
The invention creates a modified alumina product that copies the desirable dispersibility characteristic of citric acid modified alumina at high pH, but uses a different chemical approach (phosphono group containing modifier) to achieve the same functional outcome without the harmful viscosity increase side effect.
2Object-affected harmful factors
If a second carboxylic acid like malonic acid is added to reduce viscosity of citric acid modified alumina, then viscosity is reduced, but the amount of modifier increases substantially and complicates ceramic production
Solution Approach 1:
The patent extracts and eliminates the need for multiple modifying agents by using a single phosphono group containing compound that simultaneously provides both dispersibility and low viscosity characteristics. This removes the complexity of adding and managing multiple modifiers (citric acid plus malonic acid) and their associated interactions during ceramic production.
Solution Approach 2:
The phosphono group containing modifier performs multiple functions simultaneously: it provides dispersibility at high pH, maintains low viscosity, and avoids the complications of multiple modifiers. This single agent achieves what previously required a combination of at least two different modifying agents.
3Object-affected harmful factors
If additional modifying agents are used to address viscosity issues, then viscosity control is improved, but modifier loading increases which can result in complications during forming and burnout stages
Solution Approach 1:
The patent changes the chemical nature of the modifier from carboxylic acid-based (citric acid, malonic acid) to phosphono group containing compounds. This parameter change fundamentally alters how the modifier interacts with alumina and water, achieving effective viscosity control at lower loadings due to the different mechanism of action of phosphono groups compared to carboxylic acids.
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 method achieves high dispersibility and low viscosity of the modified alumina at elevated pH, similar to citric acid modified materials but with reduced viscosity issues and lower modifier content, making it suitable for ceramic production.
Implementation Method 1
adding a phosphono group containing modifier to the alumina to produce a surface modified alumina
Implementation Method 2
aging the alumina to form an aged alumina by hydrothermal treatment until the alumina has a crystallite size of 35 to 450 Å
Data Source
AI summary
The present invention is directed to a method for producing a modified alumina by modifying a surface of an alumina with the addition of a phosphono group containing modifier. The invention is further directed to a modified alumina produced according to the method of the present invention and to a modified alumina having specific characteristics.