Silane-Terminated Sealant Composition With Reactive Plasticizer
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Solution Overview
Problem
Existing curable compositions using phthalate-based plasticizers in construction sealants face issues such as migration, health hazards, and adverse effects on mechanical properties, while known reactive plasticizers compromise application properties and mechanical strength.
Innovation Solution
A curable silane-terminated polymer composition incorporating monofunctional alkoxy silane-terminated polymers as reactive plasticizers, along with a catalyst and filler, to reduce phthalate use and maintain low viscosity and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phthalate-based plasticizers are used in construction sealants, then flexibility and viscosity optimization are improved, but health hazards and migration issues occur
Solution Approach 1:
The patent changes the chemical structure of plasticizers from small-molecule phthalates to polymeric silane-terminated compounds. This parameter change transforms the plasticizer into a reactive species that incorporates into the crosslinked network, eliminating migration while maintaining flexibility. The silane-terminated polymer chains provide the necessary flexibility through their polymeric nature rather than through small-molecule plasticization.
Solution Approach 2:
The invention creates a composite system where silane-terminated polymers serve dual functions: as the base polymer providing structural integrity and as reactive plasticizers providing flexibility. The crosslinked network composite structure integrates both structural and flexible components, eliminating the need for separate phthalate-based plasticizers that would migrate and cause harm.
2Strength
If conventional plasticizers are used to improve mechanical performance, then viscosity and flexibility are optimized, but mechanical properties deteriorate over time due to migration
Solution Approach 1:
The silane-terminated plasticizers are introduced in a reactive state before curing, allowing them to become permanently bonded to the polymer matrix during the crosslinking process. This preliminary reactive incorporation ensures that the plasticizing effect is established before the material is put into service, and the bonds formed during curing prevent any future migration or degradation of mechanical properties.
Solution Approach 2:
The invention replaces the concept of temporary, migrating plasticizer molecules with permanent polymer chains that are an integral part of the crosslinked network. The silane-terminated polymers serve as both structural and plasticizing components, eliminating the need for separate additive plasticizers that would eventually migrate and fail.
3Object-affected harmful factors
If reactive plasticizers are used to prevent migration, then health hazards are reduced, but application properties and mechanical strength are compromised
Solution Approach 1:
The patent optimizes the molecular weight and silane content parameters of the silane-terminated polymers to achieve the right balance between reactivity and processability. By controlling these parameters, the material maintains low viscosity and good application properties while the reactive silane groups ensure permanent bonding to prevent migration.
Solution Approach 2:
The invention applies different functional characteristics to different parts of the polymer structure: the silane-terminated end groups provide reactivity for network formation and migration prevention, while the polymeric backbone provides the necessary flexibility and mechanical properties. This local differentiation of function within the molecule resolves the contradiction between reactivity and processability.
4Reliability
If reactive plasticizers with high reactivity are used, then migration is prevented, but viscosity increases and application becomes difficult
Solution Approach 1:
The patent carefully controls the molecular weight and silane group density parameters of the reactive plasticizers. By optimizing these parameters, the material achieves sufficient reactivity for migration prevention while maintaining low enough viscosity for easy application. The silane-terminated polymer chains are designed to provide reactivity without excessive molecular size that would increase viscosity.
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 composition achieves low extrusion force, improved mechanical properties, and stability under heat, with reduced migration and enhanced application properties, making it suitable for construction and industrial applications.
Implementation Method 1
which hydrolyze under the influence of moisture, condense with one another as silanol groups
Implementation Method 2
condense with one another as silanol groups and thus form a covalently bonded network
Implementation Method 3
at least one catalyst C
Data Source
AI summary
The invention relates to curable compositions based on silane-terminated polymers (STP) comprising at least one organic polymer P having on average between 1.5 to 3 reactive silane groups selected from methyl dimethoxy silyl or triethoxy silyl and at least one reactive plasticizer RP having on average between 0.3 to 1.5 reactive silane groups selected from methyl dimethoxy silyl and at least one filler F and at least one catalyst C. The curable STP composition of the invention can be formulated to reduce or completely omit the necessary amount of common, in particular phthalate-based plasticizers, lower the viscosity and improve the mechanical and application properties of the sealant. The inventive composition also shows improved stability upon heat treatment compared to state-of-the-art references. Furthermore, the invention relates to the use of the curable STP composition as a sealant or adhesive, in particular as an industrial sealant or construction sealant. Also, the invention relates to objects, in particular to buildings or a part of a building built with the curable STP composition.