Gradient Copolymers for Phosphate-Free Dishwashing
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Solution Overview
Problem
Automatic dishwashing detergents face challenges in producing a spotless, film-free appearance due to insoluble deposits from non-phosphate builders, particularly in hard water conditions, where existing compositions either leave visible residues or fail to effectively sequester calcium and magnesium ions.
Innovation Solution
A random polymer comprising 90-100% C3-C6 carboxylic acid monomer units and 30-80% sulfonic acid monomer units, produced through a multi-stage polymerization process, is used in a detergent composition that includes carbonate, silicate, non-ionic surfactants, sodium percarbonate, and 1-hydroxyethanediphosphonic acid, which effectively sequesters calcium and magnesium ions and prevents insoluble deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non-phosphate builders (citrate, carbonate, silicate) are used to sequester calcium and magnesium, then phosphate-free cleaning is achieved, but insoluble visible deposits are left on washed items
Solution Approach 1:
The patent changes the chemical parameters of the detergent by introducing a specific polymer composition with controlled carboxylic acid and sulfonic acid monomer units. This polymer modifies the sequestration mechanism to prevent insoluble deposit formation while maintaining calcium and magnesium ion binding capability, thus resolving the contradiction between phosphate-free cleaning and deposit prevention.
Solution Approach 2:
The patent employs a composite polymer structure combining carboxylic acid monomer units (for calcium/magnesium sequestration) and sulfonic acid monomer units (for surfactant compatibility and deposit prevention). This composite molecular structure enables simultaneous achievement of phosphate-free cleaning and elimination of visible deposits.
2Productivity
If existing polymer mixtures (acrylic acid homopolymer and acrylic acid/AMPS copolymer) are used, then some cleaning performance is achieved, but spotless and film-free appearance is not produced
Solution Approach 1:
The patent applies local quality by creating a polymer with specific local regions of carboxylic acid units for ion sequestration and sulfonic acid units for surface activity. This localized functional distribution within the polymer structure enables simultaneous cleaning performance and film-free appearance, overcoming the limitations of conventional uniform polymer compositions.
Solution Approach 2:
The patent optimizes the molecular weight (3,000-30,000) and monomer composition ratios to achieve the desired balance between cleaning efficacy and film formation prevention. These parameter adjustments resolve the contradiction between maintaining cleaning performance and achieving a spotless, film-free appearance.
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 polymer-based detergent composition ensures a spotless and film-free appearance on washed items by effectively sequestering calcium and magnesium ions, preventing insoluble deposits and maintaining a clean appearance without the use of phosphates.
Implementation Method 1
Polymer-based detergent compositions ensure a spotless and film-free appearance on washed items by effectively sequestering calcium and magnesium ions
Data Source
AI summary
A polymer comprising a first fraction and a second fraction, wherein the first fraction comprises from 90 to 100 wt% polymerized C3-C6 carboxylic acid monomer units; and the second fraction comprises from 30 to 80 wt% polymerized C3-C6 carboxylic acid monomer units and from 20 to 70 wt% polymerized sulfonic acid monomer units; wherein the first fraction is from 10 to 40 wt% of the polymer and the second fraction is from 60 to 90 wt% of the polymer; the polymer has Mw from 3,000 to 30,000; and monomers are randomly distributed within each fraction.