Voided Polymer Particle Dispersion for Paint Opacity
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Solution Overview
Problem
Current polymer pigments rely heavily on styrene for mechanical stability and opacity, but styrene production is fossil-based and prone to degradation under weathering and UV radiation, necessitating a replacement that maintains opacifying efficiency and mechanical stability while being sourced from biological origins.
Innovation Solution
Aqueous polymer dispersions of voided polymer particles with a polymer core and shell, where the shell is formed from esters of acrylic or methacrylic acid with saturated carbocyclic or heterocyclic moieties, providing a high glass transition temperature and reduced fossil carbon demand, and produced through a multistage emulsion polymerization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If styrene is used to form the polymer shell, then mechanical stability and opacity are improved, but fossil carbon demand increases and weathering resistance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer shell by replacing styrene with esters of acrylic or methacrylic acid having saturated carbocyclic or heterocyclic moieties. This substitution maintains the shell's mechanical stability while eliminating the benzene ring structure that causes UV degradation, thus resolving the contradiction between strength and weathering resistance
Solution Approach 2:
The patent employs bio-based monomers that can be produced from renewable resources, replacing the fossil-based styrene. This approach reduces dependency on depleting fossil resources while providing a sustainable alternative that maintains performance characteristics without the environmental drawbacks of styrene
2Illumination intensity
If styrene is used to form the polymer shell, then opacity is improved, but biodegradability and environmental sustainability worsen
Solution Approach 1:
The patent modifies the chemical structure parameters by selecting monomers with saturated carbocyclic or heterocyclic moieties instead of aromatic styrene. These structural changes maintain the high refractive index needed for opacity while enabling biodegradability and environmental sustainability, as the saturated structures lack the aromatic rings that resist degradation
Solution Approach 2:
The patent utilizes bio-based monomers derived from renewable resources to replace fossil-based styrene. This substitution maintains the opacifying function while improving environmental sustainability and biodegradability, allowing the polymer particles to break down more easily in the environment
3Quantity of substance
If the polymer core is swollen to increase void volume, then hiding efficiency is improved, but particle stability may worsen
Solution Approach 1:
The patent creates a composite structure with a swollen polymer core containing voids for light scattering, surrounded by a protective polymer shell. This composite architecture allows the core to be highly swollen for maximum hiding efficiency while the shell provides structural stability and prevents particle collapse, resolving the contradiction between void volume and stability
Solution Approach 2:
The patent employs a polymer shell that forms a flexible yet stable protective layer around the swollen core. This shell structure can accommodate the volume expansion of the swollen core while maintaining particle integrity, enabling high hiding efficiency without sacrificing stability
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 dispersions offer stable opacifying properties comparable to styrene-based systems, with reduced fossil carbon usage and improved resistance to weathering and UV radiation, enabling the use of bio-based monomers in paint formulations.
Implementation Method 1
High scattering pigments based on polymeric pigments... allow for at least partial replacement of TiO2... The hiding efficiency of such polymer pigments depends inter alia from a low bulk density, i.e. a high proportion of voids in the core
Implementation Method 2
the collapse resistance of the polymer particles will not only depend from the stability of the voided polymer core but it will largely depend on the rigidity of the polymer shell and the efficiency of encapsulation
Implementation Method 3
at least one stage of preparing a latex of an alkali-swellable polymer, which forms the polymer core... subsequent neutralization of the thus obtained polymer latex by addition of a base in order to swell the polymer core
Implementation Method 4
at least one stage of preparing a latex of an alkali-swellable polymer, which forms the polymer core, by emulsion polymerization... at least one further stage of emulsion polymerizing the monomers forming the non-film-forming polymer shell
Data Source
AI summary
The present invention relates to aqueous polymer dispersion of voided polymer particles and to a process for preparing such aqueous polymer dispersions. The present invention also relates to polymer particles, in particular powders of said polymer particles, which are obtained by drying a polymer dispersion. Further aspects of the present invention relate to the use of such voided polymer particles and the polymer dispersions as opacifiers and to paints containing such aqueous polymer dispersions. The voided polymer particles comprise: i) an alkali swellable polymer core of polymerized ethylenically unsaturated monomers M(i) comprising polymerized acid monomers M(i.ac) in an amount sufficient for allowing the polymer core to swell at a pH of at least pH 7.5; ii) an intermediate polymer layer of polymerized ethylenically unsaturated monomers M(ii); and iii) a polymer shell of polymerized ethylenically unsaturated monomers M(iii) having a theoretical glass transition temperature according to Fox of at least 60° C. where the monomers M(iii) comprise at least 10% b.w., based on the total weight of the monomers M(iii), of one or more monomers M(iii.a) whose homopolymers have a glass transition temperature of at least 50° C., where the monomer M(iii.a) is selected from the group consisting of C5-C20-cycloalkyl esters of acrylic acid, C5-C20-cycloalkyl esters of methacrylic acid, C5-C20-cycloalkylmethyl esters of acrylic acid, C5-C20-cycloalkylmethyl esters of methacrylic acid, where cycloalkyl in the aforementioned monomers is mono-, bi- or tricyclic and may be unsubstituted or carry 1, 2, 3 or 4 methyl groups; C3-C20-heterocycloalkyl esters of acrylic acid, C3-C20-heterocycloalkyl esters of methacrylic acid, C3-C20-heterocycloalkylmethyl esters of acrylic acid, C3-C20-heterocycloalkylmethyl esters of methacrylic acid, where heterocycloalkyl in the aforementioned monomers has a total of 5 to 16 ring-forming atoms, where 1, 2 or 3 non-adjacent ring-forming atoms are oxygen atoms while the remainder of the ring-forming atoms are carbon atoms, and where heterocycloalkyl is mono-, bi- or tricyclic and may be unsubstituted or carry 1, 2, 3 or 4 methyl groups; di-C1-C2-alkyl esters of itaconic acid; and combinations thereof.