Silane-Terminated Polymer Production via Segmented Reaction
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Solution Overview
Problem
The production of silane-terminated polymers is hindered by the toxicity and excess requirement of isocyanatoalkyl-functional alkoxysilanes, leading to wastage and prolonged reaction times, which are economically inefficient and result in the presence of toxic residues in the final product.
Innovation Solution
A process involving the reaction of hydroxy-functional polymers with isocyanate-functional silanes in excess, followed by a second reaction step using hydroxy-functional oligomers or polymers to utilize the remaining isocyanate groups, thereby minimizing wastage and achieving complete silane termination while avoiding toxic residues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If isocyanatoalkyl-functional alkoxysilanes are used in excess to ensure complete silane termination, then silane termination efficiency is improved, but toxic residue in final product increases and material wastage occurs
Solution Approach 1:
The patent segments the reaction process into two distinct stages: first, silane termination using isocyanatoalkyl-functional alkoxysilane to achieve complete chain termination; second, scavenging of excess isocyanate groups using a separate isocyanate-reactive compound. This segmentation allows each stage to optimize for its specific function while preventing toxic residue carryover.
Solution Approach 2:
The patent introduces an intermediary substance (isocyanate-reactive compound such as alcohol or amine) that specifically targets and neutralizes excess isocyanate groups. This intermediary acts as a bridge between the silane termination step and the final product, eliminating toxic residues without interfering with the primary silane termination function.
2Productivity
If isocyanatoalkyl-functional alkoxysilanes are used in excess to maintain high reaction rate, then productivity is improved, but material wastage increases due to subsequent scavenging
Solution Approach 1:
The patent extracts the harmful function (excess isocyanate groups) from the system by introducing a selective scavenging step. The isocyanate-reactive compound specifically removes unreacted isocyanate groups without affecting the silane-terminated polymer product, thereby recovering valuable materials and reducing wastage.
Solution Approach 2:
The patent changes the chemical parameters of the system by introducing compounds with different reactivity profiles. The isocyanate-reactive compound has high specificity for isocyanate groups, allowing selective reaction that transforms excess reactive groups into non-reactive byproducts, thus controlling material utilization efficiency.
3Object-affected harmful factors
If batchwise production is used to allow for scavenging of isocyanate residues, then product purity is improved, but plant occupancy time and production cost increase
Solution Approach 1:
The patent implements a continuous production process where the scavenging reaction occurs in-line immediately following the silane termination step. This continuous approach eliminates idle time between reactions, maintains steady-state operation, and reduces plant occupancy time while still achieving complete removal of isocyanate residues.
4Productivity
If continuous production is used to maximize throughput, then productivity is improved, but reaction rate control becomes more critical and difficult
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-mixing the isocyanate-reactive compound at the exact stoichiometric amount needed to neutralize expected excess isocyanate groups. This preliminary preparation simplifies the continuous process control, as the scavenging step becomes a straightforward mixing operation rather than a complex controlled reaction.
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
This process allows for rapid and efficient production of silane-terminated polymers with improved adhesion properties and reduced toxicity, enabling the production of high-quality adhesives and sealants with enhanced mechanical properties.
Implementation Method 1
The isocyanate groups react with the terminal hydroxyl groups of the polyether, thus permitting virtually complete chain termination with reactive silane functions
Implementation Method 2
On contact with water or atmospheric moisture, these alkoxysilane-terminated polymers are capable even at room temperature of undergoing condensation with one another, with elimination of the alkoxy groups
Data Source
AI summary
The invention provides a process for preparing a mixture (M) which comprises silane-terminated polymers (SP1) of the general formula (I)Y1—[O—C(═O)—NH—(CR12)b—SiRa(OR2)3-a]x (I),optionally silane-terminated polymers (SP2) of the general formula (II)Y2—[O—C(═O)—NH—(CR12)b—SiRa(OR2)3-a]z (II)and hydroxy-functional polymers (SP3) of the general formula (III)Y2—[O—C(═O)—NH—(CR12)b—SiRa(OR2)3-a]z-z1(OH)z1 (III)where Y1 and Y2 are polymer radicals and R, R1, R2, x, z, z1, a and b have the definitions indicated in claim 1, wherein, in a first process step, at least one polymer (HP1) of the general formula (IV)Y1—[OH]x (IV)reacts with at least one isocyanate-functional silane (S) of the general formula (V)O═C═N—(CR12)b—SiRa(OR2)3-a (V)to give silane-terminated polymers (SP1),and, in a second process step, the unreacted isocyanate groups of the isocyanate-functional silane (S) of the general formula (V) are reacted with at least one oligomer or polymer (HP2) of the general formula (VI)Y2(OH)z (VI);polymer mixtures (M) preparable by the process; and use of the polymer mixtures (M) for producing adhesives and sealants and also coatings.