Phosphorus-Free Dishwashing Detergent Polymers for Spot Reduction
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Solution Overview
Problem
Phosphate-free automatic dishwashing detergents face challenges in preventing spotting and insoluble deposits due to the use of non-phosphate builders, which can leave visible deposits on washed items.
Innovation Solution
A detergent composition comprising specific polymers made from (meth)acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, carbonate, citrate, and a bleaching agent, with a controlled weight ratio and molecular weight, designed to minimize elemental phosphorus content and optimize performance in reducing spotting and deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-phosphate builders (citrate, carbonate, silicate) are used to replace phosphates for sequestering calcium and magnesium, then phosphorus content is reduced, but visible insoluble deposits and spotting occur on washed items
Solution Approach 1:
The patent introduces a specific polymer (polyacrylamide or polyacrylic acid with molecular weight 10,000-100,000) as an intermediary substance that mediates between the non-phosphate builders and the calcium/magnesium ions. This polymer acts as a sequestering agent that prevents the formation of insoluble deposits while maintaining the water softening function, thereby resolving the contradiction between reducing phosphorus and preventing spotting.
Solution Approach 2:
The patent changes the molecular weight parameter of the polymer from conventional ranges to specifically 10,000-100,000, and adjusts the dosage to 0.1-5 wt% of the detergent composition. This parameter optimization enables the polymer to effectively sequester calcium and magnesium without forming visible deposits, thus reducing phosphorus content while preventing spotting.
2Object-affected harmful factors
If polymers made from acrylic acid, maleic acid and AMPS are used to inhibit scale from non-phosphate builders, then spotting is reduced, but the detergent composition lacks optimal performance
Solution Approach 1:
The patent changes the polymer type from copolymers of acrylic acid, maleic acid and AMPS to homopolymers of polyacrylamide or polyacrylic acid with specifically controlled molecular weights of 10,000-100,000. This parameter change optimizes both the spotting inhibition capability and the overall detergent performance, achieving reliable cleaning results while preventing deposits.
Solution Approach 2:
The patent extracts the essential function of scale inhibition from complex copolymer systems and achieves it through simpler polyacrylamide or polyacrylic acid polymers. By taking out the core sequestering function and implementing it through a simpler polymer system with optimized molecular weight, the patent achieves both spotting reduction and optimal detergent performance.
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 composition effectively reduces spotting and insoluble deposits, providing a spotless and film-free appearance on washed items while maintaining a low phosphorus content, thus addressing the limitations of existing phosphate-free detergents.
Implementation Method 1
non-phosphate builders, such as salts of citrate, carbonate, silicate, disilicate, bicarbonate, aminocarboxylates and others to sequester calcium and magnesium from hard water
Implementation Method 2
Polymers made from acrylic acid, maleic acid and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) are known for use in inhibiting the scale produced from non-phosphate builders
Data Source
AI summary
A phosphorus-free automatic dishwashing detergent composition comprising: (a) 0.5 to 8 wt% of a first polymer comprising polymerized units of: (i) 60 to 82 wt% (meth)acrylic acid, (ii) 10 to 30 wt% of a monoethylenically unsaturated dicarboxylic acid and (iii) 8 to 25 wt% 2-acrylamido-2-methylpropanesulfonic acid (AMPS); and having Mw from 5,000 to 100,000; (b) 0.5 to 8 wt% of a second polymer comprising polymerized units of: (i) 60 to 95 wt% (meth)acrylic acid, (ii) 5 to 40 wt% 2-acrylamido-2-methylpropanesulfonic acid (AMPS); and having Mw from 5,000 to 100,000; (c) 15 to 50 wt% carbonate, (d) 5 to 50 wt% citrate and (e) 10 to 30 wt% of a bleaching agent.