Continuous Mixing for Blocked Prepolymer Production
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Solution Overview
Problem
The production of blocked prepolymers for additive manufacturing is complicated by high viscosities and lengthy reaction times at low temperatures, leading to issues with heat transfer, foaming, and discoloration, making it difficult to scale to larger batches.
Innovation Solution
Employing continuous feed mixing processes instead of batch mixing, using a static or dynamic mixer with temperature control, to produce reactive blocked prepolymers at higher reaction rates with reduced discoloration and controlled inhibitor levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If batch mixing is used at low temperatures (35-50°C) to block free isocyanate groups, then the blocking reaction can proceed, but the reaction mixture viscosity becomes high and mixing speed increases significantly
Solution Approach 1:
The patent transitions from batch mixing to continuous mixing, where the blocking reaction and mixing occur simultaneously in a continuous flow system. This eliminates the need for separate heating and mixing stages, maintaining continuous useful action throughout the process and resolving the contradiction between temperature control and mixing efficiency.
Solution Approach 2:
The patent employs dynamic mixing conditions in a continuous flow reactor, where mixing intensity and residence time can be adjusted independently. This dynamic approach allows optimal mixing at the specific temperature required for blocking without the constraints of batch processing, resolving the contradiction between temperature maintenance and mixing speed.
2Temperature
If batch mixing is used at low temperatures to block free isocyanate groups, then the blocking reaction can proceed, but defoaming time increases significantly
Solution Approach 1:
The continuous mixing system allows defoaming to occur continuously alongside the blocking reaction, rather than as a separate sequential step. This eliminates idle defoaming time and maintains continuous productive action, resolving the contradiction between temperature control and defoaming time.
3Temperature
If TBAEMA addition time is extended to control reaction temperatures at large scales, then temperature control improves, but the production time becomes lengthy (1 to 16 hours)
Solution Approach 1:
The continuous flow reactor enables simultaneous temperature control and rapid production by maintaining continuous reaction and mixing. The system achieves both precise temperature control for large batches and high production rates, eliminating the inverse relationship between temperature control duration and production speed.
Solution Approach 2:
The patent changes the operational parameters from batch-mode time-temperature profiles to continuous-flow residence time and flow rate control. This parameter transformation allows independent optimization of temperature control and production rate, resolving the contradiction between temperature management and productivity.
4Stability of the object's composition
If mixing speed is increased to homogenize large batch mixtures, then homogeneity improves, but heat transfer problems and foaming increase
Solution Approach 1:
The continuous flow system segments the large batch mixture into continuous small-volume elements that mix efficiently as they flow through the reactor. This segmentation provides inherent surface area for heat transfer and prevents bulk foaming problems while maintaining composition homogeneity through continuous mixing.
Solution Approach 2:
The patent transitions from three-dimensional batch mixing to one-dimensional continuous flow mixing, fundamentally changing the mixing geometry. This dimensional change eliminates heat transfer limitations and foaming issues associated with large batch volumes while maintaining homogeneity through continuous processing.
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 approach allows for rapid production of reactive blocked prepolymers with improved mixing efficiency, reduced discoloration, and controlled inhibitor consumption, enabling the production of high-quality resins for additive manufacturing.
Implementation Method 1
continuously mixing a first precursor composition and a second precursor composition, the first precursor composition comprising, consisting essentially of, or consisting of a polyisocyanate oligomer, and the second precursor composition comprising an amine (meth)acrylate to produce said composition comprising a reactive blocked prepolymer
Implementation Method 2
the continuous mixing occurs at a temperature of from 0° C. or 10° C. to 30° C., 40° C., 50° C., 60° C., 70° C., or 80° C.
Implementation Method 3
using a static or dynamic mixer with temperature control
Data Source
AI summary
Provided according to embodiments of the invention are methods for the rapid production of a composition that includes a reactive blocked prepolymer. Such methods may include continuously mixing a first precursor composition and a second precursor composition, the first precursor composition including a polyisocyanate oligomer and the second precursor composition including an amine (meth)acrylate to produce the composition that includes a reactive blocked prepolymer.