Acrylic Microcapsule Wall Composition for Low Evaporation PCM Storage
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Solution Overview
Problem
Conventional microcapsules used in textiles and building materials for latent heat storage suffer from high evaporation rates and washout losses due to insufficient capsule tightness, which affects their durability and performance in maintaining temperature stability.
Innovation Solution
Microcapsules with a capsule wall constructed from 30% to 90% C1-C24-alkyl esters of acrylic and/or methacrylic acid, 10% to 70% divinyl and polyvinyl monomers, and 0% to 30% miscellaneous monomers, with a predominantly lipophilic core and controlled particle size distribution, are developed using in situ polymerization and Pickering systems for enhanced stability and tightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microcapsules with highly crosslinked methacrylic ester polymer capsule walls are used, then the capsule structure is stable, but the evaporation rate is high and washout losses occur due to insufficient tightness
Solution Approach 1:
The capsule wall is constructed as a composite material comprising at least two different polymers: a first polymer based on polyacrylic acid/poly methacrylic acid and a second polymer based on polyvinylidene fluoride/polyvinyl fluoride. This composite structure combines the advantages of both materials to achieve improved tightness and reduced evaporation rates while maintaining structural stability.
Solution Approach 2:
The invention changes the chemical composition parameters of the capsule wall by incorporating specific polymer combinations with defined weight ratios (1:99 to 50:50). This parameter optimization allows the capsule wall to achieve the desired balance between tightness and low evaporation rate, resolving the technical contradiction.
2Reliability
If conventional microcapsules are used in textiles, then they provide latent heat storage, but they suffer from weight loss during dry cleaning due to insufficient tightness
Solution Approach 1:
The composite capsule wall structure with the first polymer (polyacrylic acid/poly methacrylic acid) providing structural integrity and the second polymer (polyvinylidene fluoride/polyvinyl fluoride) enhancing chemical resistance, together achieve improved durability to dry cleaning processes while minimizing weight loss of the encapsulated latent heat storage material.
3Adaptability or versatility
If microcapsules with smaller particle sizes are produced for textile applications, then they can be better incorporated into textiles, but the manufacturing precision and uniformity become more difficult to control
Solution Approach 1:
The invention optimizes particle size parameters within specific ranges (0.5-100 μm average diameter) and controls the polymer composition ratios to achieve uniform microcapsule formation. This parameter control enables better textile incorporation while maintaining manufacturing precision and product uniformity.
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 microcapsules exhibit reduced evaporation rates and improved durability, maintaining temperature stability effectively in both textile and building material applications, with enhanced resistance to dry cleaning and thermal loads.
Implementation Method 1
The microcapsules exhibit reduced evaporation rates and improved durability, maintaining temperature stability effectively
Implementation Method 2
Textiles combined with latent heat storage media have been studied as a novel combination of materials in recent years. The working principle of latent heat storage media, often also known as phase change materials (PCMs), relies on the transformation enthalpy which arises during the solid/liquid phase transition and which signifies an absorption of energy or release of energy to the environment.
Data Source
AI summary
The present invention concerns microcapsules comprising a capsule core and a capsule wall, the capsule wall being constructed from30% to 90% by weight of one or more C1-C24-alkyl esters of acrylic and/or methacrylic acid, acrylic acid, methacrylic acid and/or maleic acid (monomers I),10% to 70% by weight of a mixture of divinyl and polyvinyl monomers (monomers II), the fraction of polyvinyl monomers being in the range from 2% to 90% by weight based on the monomers II, and also0% to 30% by weight of one or more miscellaneous monomers (monomer III),all based on the total weight of the monomers, a process for their production and their use in textiles, bindered building materials and heat transfer fluids.