Polyurea Microcapsule Production Without pH Adjustment
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Solution Overview
Problem
Existing processes for producing polyurea/polyurethane microcapsules require pH value adjustment and are limited in encapsulating fragrances or flavorings with aldehyde, carboxylic acid, or ester functionalities due to instability and loss of active ingredients during encapsulation.
Innovation Solution
A method involving emulsifying polyisocyanate and the active ingredient in an aqueous solution with a protective colloid and emulsifier, followed by sequential crosslinking with amino acid, hydroxyl group donor, and basic amine or guanidinium group donor without pH adjustment, allowing for stable and efficient encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pH value adjustment is used in the encapsulation process, then the stability of the microcapsule production is improved, but the complexity of the manufacturing process increases and the loss of active ingredients occurs
Solution Approach 1:
The invention changes the chemical parameters of the system by using polyisocyanates with specific functionality (≥2 NCO groups) that enable crosslinking without pH adjustment. The process operates at neutral pH by utilizing the inherent reactivity of isocyanate groups with amino acid hydrochlorides, hydroxyl group donors, and basic amines, eliminating the need for acid/base pH control while maintaining encapsulation stability.
Solution Approach 2:
The invention extracts and eliminates the pH adjustment step from the manufacturing process. By removing the acid/base addition step that causes complexity and potential active ingredient loss, the process achieves stability through the intrinsic chemical properties of polyisocyanate-based crosslinking, which proceeds effectively at neutral pH conditions.
2Ease of manufacture
If pH-dependent crosslinking is used, then the encapsulation process is simplified, but the adaptability to different active ingredients (especially those with aldehyde, carboxylic acid, or ester functionalities) is reduced
Solution Approach 1:
The invention creates a universal encapsulation system based on polyisocyanate crosslinking that can accommodate diverse active ingredients including those with aldehyde, carboxylic acid, ester, and other functional groups. The multi-functional crosslinking approach (using amino acid hydrochlorides, hydroxyl group donors, and basic amines) provides broad compatibility while maintaining process simplicity, as the isocyanate groups react with various nucleophilic functional groups under neutral conditions.
Solution Approach 2:
The invention changes the chemical reactivity parameters by utilizing polyisocyanates with functionality of 2 or more NCO groups, enabling crosslinking reactions that are independent of pH. This parameter change allows the system to work with a wide range of active ingredients that would otherwise be incompatible with pH-dependent encapsulation methods, particularly those containing sensitive functional groups like aldehydes, carboxylic acids, and esters.
3Loss of substance
If polyisocyanate crosslinking is performed without catalyst and pH adjustment, then the purity of the microcapsule product is improved, but the productivity and reaction speed decrease
Solution Approach 1:
The invention applies preliminary action by adding a catalyst at the beginning of the crosslinking process, before the main polymerization occurs. This pre-catalyst addition ensures that the crosslinking reaction proceeds at an appropriate speed from the start, improving productivity without compromising the purity of the final product. The catalyst is incorporated into the system in a controlled manner that prevents side reactions and maintains product quality.
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
This method produces microcapsules with improved stability and sensory properties, enabling effective encapsulation and targeted release of lipophilic active ingredients without pH-dependent instability issues.
Implementation Method 1
carrying out a first polymerization and/or crosslinking step by adding at least one amino acid or an amino acid hydrochloride and a catalyst; carrying out a second polymerization and/or crosslinking step by adding at least one hydroxyl group donor; carrying out a third polymerization and/or crosslinking step by adding at least one basic amine and/or a guanidinium group donor
Implementation Method 2
polyurea/polyurethane microcapsules which are produced by several pH-dependent crosslinking steps of polyisocyanates with an amine reacting at an acidic pH and then with an amine reacting at an alkaline pH
Implementation Method 3
emulsifying polyisocyanate and the active ingredient in an aqueous solution with a protective colloid and emulsifier
Implementation Method 4
providing an external aqueous phase comprising at least one protective colloid and optionally at least one emulsifier
Implementation Method 5
adding at least one amino acid or an amino acid hydrochloride and a catalyst
Data Source
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AI summary
The invention relates to a method for producing polyurea/polyurethane microcapsules, including at least one lipophilic active substance, preferably perfume- or aroma-containing polyurea/polyurethane microcapsules, which can be carried out independently of the ph value, in contrast to the methods for producing polyurea/polyurethane microcapsules in the prior art. The invention also relates to polyurea/polyurethane microcapsules that can be produced with the method according to the invention. In another embodiment, the invention relates to the use of this type of microcapsules or microcapsule-dispersions to produce household products, textile care products, detergents, fabric softeners, cleaning agents, scent boosters, scent lotions and fragrance intensifiers, cosmetics, body care products, agricultural products, pharmaceutical products, printed coatings for paper and similar. The invention also relates to consumer products comprising polyurea/polyurethane microcapsules of this type.