Benefit Agent Delivery Particles with Polyacrylate Shell
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Solution Overview
Problem
Benefit agents in consumer products, such as perfumes and fabric softeners, face challenges in maintaining effectiveness due to physical or chemical characteristics that lead to leakage, incompatibility with other components, and instability in slurries, particularly in fabric treatment products, resulting in reduced odor retention and performance.
Innovation Solution
The development of benefit agent containing delivery particles with a polyacrylate shell and a judicious selection of colloid type, benefit agent solvent system, and molecular weight, which minimizes leakage and enhances odor profile by controlling the shell strength and molecular weight through a radical polymerization process, and refining the slurry to remove free polyvinyl alcohol and minimize salt levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shell strength is increased to minimize benefit agent leakage, then leakage is reduced, but the odor profile (prerub and post-rub benefits) is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight of polyvinyl alcohol (specifically 65,000-110,000 Da) and the degree of hydrolysis (85-95%) to optimize the shell's permeability and strength balance. This allows the shell to be strong enough to prevent leakage while remaining permeable enough to deliver odor profile benefits at different stages (prerub and post-rub).
Solution Approach 2:
The patent uses composite materials by combining polyvinyl alcohol with specific additives including borax (0.1-5% based on PVA weight) and optional crosslinking agents. This composite shell structure achieves both mechanical strength for leakage prevention and controlled permeability for odor delivery, resolving the contradiction between shell strength and benefit agent release.
2Strength
If polyvinyl alcohol is used as colloid to manufacture particles, then shell strength is improved, but slurry stability is decreased due to depletion flocculation
Solution Approach 1:
The patent introduces borax as an intermediary substance that mediates between the polyvinyl alcohol shell and the slurry environment. The borax forms crosslinks with the PVA chains, reinforcing the shell structure while the controlled amount (0.1-5% of PVA weight) prevents excessive flocculation, thus maintaining slurry stability while achieving sufficient shell strength.
Solution Approach 2:
The patent carefully controls the concentration of polyvinyl alcohol in the slurry (0.1-0.8% based on continuous phase water weight) and optimizes the molecular weight (65,000-110,000 Da) to balance shell strength formation with slurry stability. This parameter optimization prevents depletion flocculation while ensuring adequate shell strength for leakage prevention.
3Reliability
If the level of polyvinyl alcohol is increased to improve shell strength, then leakage is reduced, but free polyvinyl alcohol in slurry increases causing depletion flocculation
Solution Approach 1:
The patent optimizes the PVA concentration parameter to a specific range (0.1-0.8% of continuous phase water weight) and controls the PVA to benefit agent core ratio (0.1-1.1% based on core weight). This precise parameter control ensures sufficient shell strength for benefit agent retention while preventing excess free PVA that would cause depletion flocculation and slurry instability.
Solution Approach 2:
Borax serves as a mediator that binds to polyvinyl alcohol chains, effectively reducing the amount of free PVA in the slurry. This crosslinking mechanism allows the system to achieve adequate shell strength with lower overall PVA levels, thereby preventing depletion flocculation while maintaining benefit agent retention.
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 solution provides enhanced prerub and post-rub benefits to wet and dry fabrics with decreased benefit agent leakage, maintaining a stable odor profile and improving delivery efficiency in fabric care compositions.
Implementation Method 1
the source of this problem was that some of the polyvinyl alcohol used to manufacture the particles is found as free polyvinyl alcohol in the slurry
Implementation Method 2
Unfortunately, such particles leak benefit agent over time, possibly via diffusion
Implementation Method 3
Such free polyvinyl alcohol results in depletion flocculation of the benefit agent containing delivery particles that destabilizes the slurry
Data Source
AI summary
The present invention relates to compositions of benefit agent containing delivery particles and slurries comprising benefit agent containing delivery particles, compositions comprising the particles, and processes for making and using the aforementioned particles and compositions. Such slurries and benefit agent containing delivery particles are stable and when employed in compositions, for example, cleaning or fabric care compositions, the particles in such slurries increase the efficiency of benefit agent delivery, thereby allowing reduced amounts of benefit agents to be employed. In addition to allowing the amount of benefit agent to be reduced, such particles allow a broad range of benefit agents to be employed. The compositions can comprise particles, cakes, powders, particulates, aggregates, aggregate clusters and slurries comprising the benefit agent containing delivery particles.