Membrane-Sealing Polyurethane Composition for Low Elution and Fillability
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Solution Overview
Problem
Existing polyurethane resin-forming compositions for membrane-sealing materials face issues such as high viscosity, poor compatibility during molding, and high elution of low-molecular-weight reaction products, leading to filling troubles and poor appearance of molded products.
Innovation Solution
A polyurethane resin-forming composition comprising a polyisocyanate prepolymer derived from diphenylmethane diisocyanate and an active hydrogen-containing compound, with a curing agent containing castor oil polymerized polyol and a hydroxyl group-containing amine-based compound, optimized to reduce viscosity and elution of low-molecular-weight reaction products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a polyurethane resin-forming composition comprising MDI and castor oil polymerization product is used, then the elution amount of low-molecular-weight reaction product is reduced, but the viscosity of the base agent becomes high causing filling troubles
Solution Approach 1:
The invention changes the chemical structure parameters of the polyol component by specifying a castor oil polymerization product with controlled molecular weight distribution and functional group content. This modifies the reaction kinetics and viscosity characteristics while maintaining low elution of low-molecular-weight products, thus resolving the contradiction between reduced elution and improved fillability.
Solution Approach 2:
The invention uses a composite curing agent system comprising both the castor oil polymerization product and the hydroxyl group-containing amine-based compound. This composite approach allows the castor oil polymerization product to provide structural integrity and low elution, while the amine-based compound facilitates rapid curing and maintains workability, thereby resolving the viscosity-f fillability contradiction.
2Strength
If a polyurethane resin-forming composition with high mechanical strength is used, then the productivity is improved, but the compatibility at the time of molding becomes poor resulting in poor appearance
Solution Approach 1:
The invention optimizes the NCO index (isocyanate group content) to a specific range that balances crosslinking density and reaction uniformity. This parameter control ensures high mechanical strength through adequate crosslinking while preventing side reactions and phase separation that would cause poor appearance, thus resolving the contradiction between strength and appearance quality.
Solution Approach 2:
The hydroxyl group-containing amine-based compound acts as an intermediary that mediates between the isocyanate groups and the castor oil polymerization product. It enables controlled crosslinking that achieves high mechanical strength while maintaining homogeneous structure and good appearance, preventing the formation of aggregates or phase separation during molding.
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 achieves improved moldability, reduced elution of low-molecular-weight reaction products, and enhanced appearance of the molded urethane resin, suitable for membrane-sealing materials and modules.
Implementation Method 1
a polyisocyanate prepolymer (A); and a curing agent (B)... to form a polyurethane resin-forming composition
Data Source
Figure 1
AI summary
Provided is a polyurethane resin-forming composition for a membrane-sealing material, the polyurethane resin-forming composition contributing to formation of (1) a urethane resin that is excellent in moldability, has a suppressed elution amount of a low-molecular-weight reaction product, and has excellent appearance or (2) a urethane resin that has a low viscosity, is excellent in cast moldability, and has a reduced water elution amount of a low-molecular-weight reaction product and a reduced solvent elution amount of a molded product. The polyurethane resin-forming composition for a membrane-sealing material comprises: a polyisocyanate prepolymer (A) or an allophanate group-containing polyisocyanate prepolymer (A') comprising a reaction product of a diphenylmethane diisocyanate (a1-1) and/or a modified product of a diphenylmethane diisocyanate (al-2), and an active hydrogen-containing compound (a2); and a castor oil polymerized polyol (b1) comprising a castor oil polymerization product.