Silane-Terminated Polymer Composition for UV and Storage Stability
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Solution Overview
Problem
Existing silane-terminated polymers suffer from inadequate UV stability and storage stability, and isocyanate-free production leads to environmentally harmful by-products at high temperatures.
Innovation Solution
A composition containing at least 20% by weight of silane-terminated polymers of formula (I) or (II), with a curing catalyst having a pKa of greater than 15, and free of base catalysts, combined with a polymer backbone of branched diol monomer units, avoids unwanted by-products and enhances storage and UV stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If silane-terminated polymers based on polyethers are used, then storage stability is improved, but UV stability deteriorates
Solution Approach 1:
The patent uses composite materials by combining silane-terminated polyester polymers with silane-terminated polyether polymers in a specific ratio (60-95 wt% polyester, 5-40 wt% polyether). This composite approach allows the formulation to inherit the UV stability of polyester while incorporating the storage stability benefits of polyether, resolving the contradiction between these two properties.
Solution Approach 2:
The patent changes the chemical composition parameters by selecting specific polyester backbones with branched diol monomer units and adjusting the ratio of polyester to polyether components. By optimizing these parameters, the formulation achieves both high storage stability and high UV stability simultaneously.
2Reliability
If silane-terminated polymers based on polyester and/or polycarbonate are used, then UV stability is improved, but storage stability deteriorates
Solution Approach 1:
The patent creates a composite system combining polyester-based silane-terminated polymers (for UV stability) with polyether-based silane-terminated polymers (for storage stability). This composite formulation resolves the contradiction by allowing both material types to contribute their respective strengths to the final sealant composition.
Solution Approach 2:
The patent optimizes the weight ratio parameters of polyester to polyether components (60-95:5-40) and selects specific polyester backbone structures with branched diol monomers. These parameter optimizations enable the formulation to achieve both high UV stability and high storage stability simultaneously.
3Object-affected harmful factors
If isocyanate-free production is used, then environmental safety is improved, but harmful by-products are generated
Solution Approach 1:
The patent changes the chemical reaction parameters by using isocyanate-based chemistry instead of isocyanate-free alternatives. This parameter change eliminates the formation of harmful phenolic by-products while maintaining environmental safety, as the isocyanate reaction pathway does not generate these problematic substances.
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 provides excellent storage stability and UV stability, preventing weathering damage to wood and reducing maintenance, while avoiding harmful by-products, suitable for wood joining applications.
Implementation Method 1
The composition contains a curing catalyst and is free of curing catalysts or residues thereof selected from the group of base catalysts having a pKa of greater than 15
Implementation Method 2
The silane-terminated polymers are prepared by known methods. A known process comprises, for example, the reaction of polyols, in particular hydroxyl-terminated polyethers, polyurethanes or polyesters, and also of hydroxyl-functional polyacrylates, with (isocyanatoalkyl)alkoxysilanes
Data Source
AI summary
A composition useful as a wood joint material includes at least 20 wt. % of a silane-terminated polymer, the polymer backbone of which is selected from a polycarbonate, a polyester, a copolymer containing a polyester and/or a polycarbonate, and a polymer containing at least one ester group and/or carbonate group. This polymer backbone contains a plurality of diol monomer, at least 60% of which have the formula HO—Z—OH, where Z is a saturated or unsaturated hydrocarbon chain optionally containing one or more heteroatoms selected from oxygen, sulphur and a tertiary nitrogen, wherein Z includes at least one side chain and/or at least one cyclic ring system and/or at least one double bond, and the composition is free from hardening catalysts or residues thereof selected from base catalysts having a pKa value greater than 15, and from by-products formed when a leaving group is split off during silane termination of the polymer.