Core/Shell Polymer Coatings for VOC Capture
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Solution Overview
Problem
Existing aqueous dispersions for capturing volatile organic compounds (VOCs) like aldehydes and formalin in indoor air are inefficient due to unstructured polymer particles, leading to inadequate film formation and increased stickiness, and lack sufficient performance in reducing VOC levels.
Innovation Solution
An aqueous dispersion of core/shell structured polymer particles with a hard/soft phase morphology, where the soft phase contains functional groups like ureido or acetoacetoxy groups, is used to form a film that irreversibly traps VOCs, with a minimum filming temperature of 0-50°C and a soft phase comprising 40-85% of the total weight, enhancing capture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unstructured polymer particles are used in aqueous dispersions, then the coating can be applied, but the film formation is inadequate and stickiness increases
Solution Approach 1:
The polymer particles are segmented into core/shell structured morphology with distinct hard phase cores and soft phase shells. This segmentation allows the hard core to provide structural integrity for proper film formation while the soft shell controls surface properties to reduce stickiness, resolving the contradiction between film formation quality and stickiness.
Solution Approach 2:
Different regions of the polymer particle are given different properties: the core has hard phase characteristics (high Tg, structural stability) while the shell has soft phase characteristics (low Tg, controlled adhesion). This local quality differentiation enables the coating to form quality films without excessive stickiness.
2Reliability
If unstructured polymer particles are used, then the coating composition is simple, but the performance in reducing VOC levels is insufficient
Solution Approach 1:
The polymer is segmented into functional zones within core/shell particles: the soft shell contains reactive functional groups (ureido, acetoacetoxy) for VOC capture, while the hard core provides structural support. This segmentation enhances VOC capture efficiency despite increased structural complexity.
Solution Approach 2:
The polymer particles are composite structures combining hard phase and soft phase materials with complementary properties. The soft phase provides chemical reactivity for VOC trapping while the hard phase ensures film integrity, achieving superior VOC capture performance.
3Reliability
If the soft phase comprises 40-85% of total weight, then VOC capture efficiency is enhanced, but the film may become too soft
Solution Approach 1:
The core/shell segmentation allows the soft phase to be concentrated in the shell region where it contacts VOCs, maximizing capture efficiency. The hard core remains intact to provide structural strength, resolving the contradiction between softness for VOC capture and strength for film integrity.
Solution Approach 2:
The soft phase is localized to the shell region (40-85% by weight) where it performs VOC capture function, while the hard core maintains overall film strength. This spatial localization of properties allows high soft phase content without compromising film strength.
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 dispersion effectively reduces VOC levels by forming a non-sticky, homogeneous film with improved reproducibility and performance in capturing aldehydes and formalin, outperforming unstructured dispersion systems.
Implementation Method 1
The polymer used according to the present invention acts as a binder in the coatings and comprises at least one function which reacts irreversibly with the functions of said volatile organic products, in particular aldehydes
Implementation Method 2
capture and irreversible trapping of volatile organic compounds
Implementation Method 3
P1 being the hard polymer phase at the heart of said particle, with a glass transition temperature Tg1 ranging from 60 to 120°C... P2 being the soft polymer phase in shell having a glass transition temperature Tg2 ranging from -20 to 40°C
Data Source
Figure 1
AI summary
The invention concerns the use of an aqueous polymer dispersion having core/shell structure particles with an FFT ranging from 0 to 50°C, the polymer phase P1 being a hard core with a Tg1 of 60 to 120°C and the polymer phase P2 being a soft shell with a Tg2 of -20 to 40°C, in which P1 comprises a monomer M1 with two polymerisable ethylenic unsaturations and an ethylenically unsaturated monomer M2 carrying a carboxylic acid/anhydride functional group, and P2, representing 40 to 85% by weight of P1 + P2, comprises, in the structure of same, units from at least one monomer M3 carrying a polymerisable ethylenic unsaturation and also a ureido functional group or a functional group having a mobile alpha-hydrogen of a ketonic carbonyl, said use being for the irreversible capturing and trapping of a volatile organic compound carrying an aldehyde, ketone or amine functional group. More particularly, said use concerns the polymer from said dispersion in the form of a film or coating.