Anti-Redeposition Polymer Composition for Low-Water Laundry Detergents
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Solution Overview
Problem
Conventional polymers used in laundry detergents are ineffective at preventing soil redeposition under low water usage conditions, requiring high dosages to achieve desired results.
Innovation Solution
A laundry detergent composition comprising a surfactant and a polymer with specific weight percentages of nitrogen-containing ethylenically unsaturated monomers and ethylenically unsaturated carboxylic acid monomers, optimized for improved soil redeposition prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymers (polyacrylic acid, carboxymethyl cellulose) are used to prevent soil redeposition, then they provide basic anti-redeposition function, but they require relatively high dosages and are ineffective under low water usage conditions
Solution Approach 1:
The patent modifies the chemical parameters of the polymer by introducing nitrogen-containing ethylenically unsaturated monomers (such as vinylimidazole, vinylpyrrolidone, or aminoethyl methacrylate) into the polyacrylic acid structure. These monomers contain basic nitrogen groups that can interact with soil particles and fabric surfaces, enhancing the anti-redeposition mechanism. The specific parameter changes include: (1) incorporating 0.1-10 mol% of nitrogen-containing monomers into the polymer chain, (2) adjusting the molecular weight to 10,000-1,000,000 Da, and (3) optimizing the charge density through the basic nitrogen groups. These parameter changes enable the polymer to maintain effective anti-redeposition performance at lower dosages (0.01-5 wt% relative to detergent weight) while being particularly effective in low water usage conditions where soil concentration is higher.
2Reliability
If higher dosages of conventional polymers are used to improve anti-redeposition effectiveness, then soil redeposition prevention improves, but the cost and environmental impact increase
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer to include basic nitrogen-containing functional groups (vinylimidazole, vinylpyrrolidone, aminoethyl methacrylate) at 0.1-10 mol% incorporation. These basic groups provide enhanced interaction with acidic soil components and fabric surfaces through electrostatic and hydrogen bonding mechanisms. This compositional change increases the polymer's affinity for soil particles and fabric, allowing effective anti-redeposition performance at reduced dosages of 0.01-5 wt% relative to detergent weight, thereby reducing polymer consumption and associated environmental impact.
Solution Approach 2:
The patent creates a composite polymer structure by copolymerizing acrylic acid (or methacrylic acid) with nitrogen-containing ethylenically unsaturated monomers. This composite structure combines the carboxylic acid groups from acrylic acid units with the basic nitrogen groups from the comonomer units, creating a zwitterionic or amphoteric character. This composite material approach enables multifunctional interaction with soil and fabric surfaces, improving anti-redeposition effectiveness per unit mass and reducing the overall polymer dosage required.
3Loss of substance
If conventional polymers are used in low water usage conditions with increased soil concentration, then water conservation is achieved, but the polymers become ineffective at preventing soil redeposition
Solution Approach 1:
The patent modifies the polymer's chemical parameters by incorporating basic nitrogen-containing monomers (vinylimidazole, vinylpyrrolidone, aminoethyl methacrylate) at 0.1-10 mol% into the polyacrylic acid structure. These basic groups provide enhanced electrostatic and hydrogen bonding interactions with soil particles and fabric surfaces, which is particularly beneficial in low water usage conditions where soil concentration is higher. The increased interaction strength allows the polymer to maintain effective anti-redeposition performance even when soils are more concentrated in the wash bath, enabling water conservation without sacrificing cleaning effectiveness.
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 effectively maintains fabric whiteness by reducing soil redeposition, even under low water conditions, outperforming conventional polymers in maintaining fabric whiteness indices.
Implementation Method 1
a polymer comprising polymerized units of: (a) from 5 to 35 wt% of at least one nitrogen-containing ethylenically unsaturated monomer... having at least one pKa value from 7 to 11, and (b) from 65 to 95 wt% of at least one ethylenically unsaturated carboxylic acid monomer
Data Source
AI summary
A laundry detergent composition comprising an anti-redeposition agent, a surfactant, and optionally a builder, wherein the anti-redeposition agent is a polymer comprising polymerized units of: (a) from 5 to 40 wt% of at least one nitrogen-containing ethylenically unsaturated monomer having at least one pKa value from 6 to 11.5, and (b) from 60 to 95 wt% of at least one ethylenically unsaturated carboxylic acid monomer.