Phosphate-Free Dishwashing Formulation with Graft Copolymers
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Solution Overview
Problem
Phosphate-free dishwashing compositions face challenges in scale inhibition, particularly on glassware, and can cause glass corrosion in machine dishwashers, necessitating improved formulations and production processes.
Innovation Solution
Formulations comprising citric acid or its alkali metal salts, a graft copolymer formed from nonionic monosaccharides, disaccharides, or polysaccharides grafted with ethylenically unsaturated mono- or dicarboxylic acids, and limited amounts of methylglycinediacetic acid and glutaminediacetic acid, which provide effective scale inhibition without glass corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If phosphate-free dishwashing compositions are used, then environmental safety is improved, but scale inhibition performance deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the formulation by replacing phosphates with specific alternatives: citric acid or alkali metal salts (0.5-5% wt), graft copolymers with specific carbohydrate backbones and side chains (0.1-5% wt), and limited amounts of MGDA/GLDA (0-0.5% wt). This parameter change maintains scale inhibition while achieving phosphate-free environmental safety.
Solution Approach 2:
The patent creates a composite inhibitor system combining multiple substances with different mechanisms: citric acid/alkali metal salts provide water softening and scale prevention, graft copolymers provide adsorption and dispersion, and MGDA/GLDA provide chelation. This composite approach achieves scale inhibition performance comparable to or exceeding phosphate-based systems while being environmentally safe.
2Reliability
If conventional polymers are used in phosphate-free compositions, then scale inhibition is improved, but glass corrosion increases
Solution Approach 1:
The patent modifies the polymer structure parameters by specifying graft copolymers with carbohydrate backbones (monosaccharides, disaccharides, oligosaccharides, or polysaccharides) grafted with ethylenically unsaturated mono- or dicarboxylic acids. This structural parameter change provides effective scale inhibition while the specific composition (including citric acid/alkali metal salts and limited MGDA/GLDA) prevents glass corrosion that occurs with conventional polymers.
3Ease of operation
If multifunctional x-in-1 detergents are used, then ease of operation is improved, but formulation complexity increases
Solution Approach 1:
The patent achieves multi-functionality by incorporating ingredients that perform multiple roles: citric acid/alkali metal salts provide water softening, scale inhibition, and pH buffering; graft copolymers provide scale inhibition, soil suspension, and water softening; MGDA/GLDA provide chelation and scale prevention. This allows a single detergent formulation to effectively clean, rinse, and soften water without requiring separate rinse aid or salt replenishment.
Solution Approach 2:
The patent merges multiple functions into a unified formulation by combining cleaning agents, scale inhibitors, water softeners, and soil suspension agents in a single composition. The specific combination of citric acid/alkali metal salts, graft copolymers, and limited MGDA/GLDA creates synergistic effects that achieve effective cleaning and rinsing in one step, eliminating the need for separate rinse aid products.
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 proposed formulations exhibit excellent scale inhibition on glassware and other dishware materials, preventing glass corrosion and persistent stains, while being suitable for machine dishwashing without the need for separate rinse aids or regenerating salts.
Implementation Method 1
the functions of cleaning, of rinsing and of water softening are combined in a single detergent formulation
Implementation Method 2
the detached soil constituents must be dispersed or emulsified in such a sustained manner that they are not deposited on the surface of the ware
Implementation Method 3
the detached soil constituents must be dispersed or emulsified in such a sustained manner that they are not deposited on the surface of the ware
Implementation Method 4
The surfactants used are chosen such that they are entrained into the rinse cycle and ensure optimal wetting and a good rinsing result therein
Data Source
AI summary
Described herein is a formulation including(A) citric acid or an alkali metal salt of citric acid,(B) at least one graft copolymer formed from(a) at least one graft base selected from nonionic monosaccharides, disaccharides, oligosaccharides and polysaccharides, and side chains, obtainable by grafting of(b) at least one ethylenically unsaturated mono- or dicarboxylic acid and(c) at least one compound of the general formula (I)where the variables are defined as follows:R1 is selected from methyl and hydrogen,A1 is selected from C2-C4-alkylene,R2 are the same or different and are selected from C1-C1-alkyl,X− is selected from halide, mono-C1-C4-alkylsulfate and sulfate,(C) a total of zero to 0.5% by weight of methylglycinediacetic acid (MGDA) and glutaminediacetic acid (GLDA) and alkali metal salts of MGDA and GLDA.