Phthalate-Free Ester Sealant Resolves Migration and Toxicity
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Solution Overview
Problem
Conventional adhesive sealants often contain phthalates, which are hazardous and can migrate out of the crosslinked sealant, leading to undesirable consequences such as unattractive stains, loss of elasticity, and adhesive failure, while also requiring several days for full crosslinking and achieving desired mechanical properties.
Innovation Solution
A phthalate-free adhesive sealant composition using an ester compound as a plasticizer, specifically an ester of formula (I) derived from monocarboxylic acids and polyols like pentaerythritol, which prevents migration and enhances mechanical properties, including elasticity, by acting as a moisture-crosslinkable prepolymer with polyurethane or alkoxysilyl end groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If phthalates are used as plasticizers in sealant compositions, then the extrudability and plasticity of the sealant are improved, but the sealant becomes hazardous to human health and the plasticizer migrates out of the crosslinked sealant causing stains, loss of elasticity, and adhesive failure
Solution Approach 1:
The patent changes the chemical parameters of the plasticizer by using esters of formula (I) with specific structural characteristics (oxycarbonylalkyl radicals with 4-20 carbon atoms) instead of conventional phthalates. This parameter change maintains the desired plasticizing properties and extrudability while eliminating the harmful CMR properties of phthalates.
Solution Approach 2:
The patent converts the potential harm of plasticizer migration into a benefit by selecting ester plasticizers that exhibit superior migration resistance compared to conventional phthalates. The specific molecular structure of the esters of formula (I) ensures they remain trapped in the crosslinked network, transforming the migration problem into an advantage of enhanced long-term stability.
2Ease of operation
If phthalates are used as plasticizers in sealant compositions, then the extrudability and plasticity of the sealant are improved, but the plasticizer migrates out of the crosslinked sealant causing loss of elasticity and adhesive failure
Solution Approach 1:
The patent changes the chemical parameters of the plasticizer by using esters of formula (I) with specific structural characteristics (oxycarbonylalkyl radicals with 4-20 carbon atoms) instead of conventional phthalates. This parameter change maintains the desired plasticizing properties and extrudability while eliminating the harmful CMR properties of phthalates.
Solution Approach 2:
The patent converts the potential harm of plasticizer migration into a benefit by selecting ester plasticizers that exhibit superior migration resistance compared to conventional phthalates. The specific molecular structure of the esters of formula (I) ensures they remain trapped in the crosslinked network, transforming the migration problem into an advantage of enhanced long-term stability.
3Reliability
If conventional sealant compositions are used, then the sealant can be applied and crosslinked, but it requires several days to achieve full crosslinking and desired mechanical properties
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating esters of formula (I) as plasticizers in combination with moisture-crosslinkable prepolymers having terminal isocyanate or alkoxysilane reactive groups. This compositional change optimizes the crosslinking kinetics, enabling the sealant to develop full mechanical properties more rapidly than conventional formulations.
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 ester-based sealant composition maintains extrudability without phthalates, achieves improved mechanical properties, and prevents migration, resulting in a stable and elastic adhesive joint with enhanced cohesion and elongation at break, while reducing exposure to hazardous substances.
Implementation Method 1
The sealant compositions also comprise a plasticizing agent for the purpose of increasing the plasticity of the composition and of decreasing its viscosity
Implementation Method 2
The reaction of these reactive groups with the water originating from the moisture of the air or of the substrate (known as crosslinking reaction) makes possible, after the introduction of the sealant into the gap between the two substrates to be assembled, the creation of a solid three-dimensional polymeric network
Implementation Method 3
the said ester does not give rise to diffusion (or migration) out of the crosslinked sealant
Data Source
AI summary
Adhesive sealant composition comprising at least one moisture-crosslinkable prepolymer and, as plasticizing agent, an ester compound of formula (I):in which:R1, R2 and R3 represent an oxycarbonylalkyl radical of 4 to 20 carbon atoms;R4 represents a hydrogen atom, a methyl or ethyl radical or else a radical: —CH2—R5 in which R5 represents an oxycarbonylalkyl radical of 4 to 20 carbon atoms.