Allophanate Polyisocyanate Bubble Reduction
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Solution Overview
Problem
Polyurethane resin-forming compositions using allophanate group-containing polyisocyanates derived from MDI and monool exhibit poor defoaming properties, leading to bubble retention in the cured resin, which is undesirable for membrane modules used in water treatment and medical applications.
Innovation Solution
Incorporating a hydroxyl group-containing polymethylsiloxane compound or a siloxane compound into the allophanate group-containing polyisocyanate composition, specifically within defined concentration ranges, to enhance the formation of a polyurethane resin with reduced bubble formation, thereby improving the sealing properties of membrane modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an allophanate group-containing polyisocyanate derived from MDI and a monool is used in a polyurethane resin-forming composition, then the viscosity is low and handleability is improved, but the defoaming properties are poor and bubbles remain in the cured resin
Solution Approach 1:
A siloxane compound is introduced as an intermediary substance into the polyisocyanate composition. The siloxane compound acts as a defoaming agent that mediates between the low-viscosity polyisocyanate and the bubble formation problem, enabling effective bubble removal while maintaining the flowability and handleability provided by the low viscosity
Solution Approach 2:
The invention creates a composite composition by combining the allophanate group-containing polyisocyanate (derived from MDI and monool) with a siloxane compound. This composite material integrates the beneficial properties of low viscosity and handleability from the polyisocyanate with the defoaming properties of the siloxane compound, resolving the contradiction between ease of operation and bubble formation
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 proposed solution effectively reduces bubble formation in the polyurethane resin, resulting in a more efficient and reliable sealing material for membrane modules, suitable for medical and industrial applications, with improved processability and adhesive strength.
Implementation Method 1
Incorporating a hydroxyl group-containing polymethylsiloxane compound or a siloxane compound into the allophanate group-containing polyisocyanate composition, specifically within defined concentration ranges, to enhance the formation of a polyurethane resin with reduced bubble formation
Data Source
AI summary
An allophanate group-containing polyisocyanate composition that contributes to the formation of a polyurethane resin with fewer bubbles is provided.Disclosed is an allophanate group-containing polyisocyanate composition (C) including a reaction product of diphenylmethane diisocyanate (A) and a hydroxyl group-containing compound (B), wherein the hydroxyl group-containing compound (B) includes a hydroxyl group-containing polymethylsiloxane compound (B-1) in an amount of 1 ppm or more and 300 ppm or less.