Polyurethane Membrane Seal Composition for Low Viscosity and Low Elution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyurethane resin compositions for membrane sealing materials have high initial viscosity upon mixing, leading to filling defects during molding, and produce low-molecular weight reaction products that elute into the membrane module, necessitating a composition with lower viscosity and reduced elution.
Innovation Solution
A composition comprising a base agent with a mixture of modified or unmodified diphenylmethane diisocyanate and an isocyanate group-terminated prepolymer, along with a curing agent containing specific compounds, achieves low viscosity and minimal elution of low-molecular weight products by using a compound represented by Formula (1) with an HLB of 9.0 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If MDI and castor oil are reacted to reduce viscosity, then the viscosity of the base agent decreases, but the amount of elution of low-molecular weight reaction products increases
Solution Approach 1:
The patent changes the molecular weight parameter of the polyol component and controls the NCO content parameter of the base agent within specific ranges. By using a polyol with number-average molecular weight of 200-1000 and controlling MDI monomer content to 35% or less, the composition achieves low viscosity while minimizing elution of low-molecular weight products.
Solution Approach 2:
The patent creates a composite composition by combining specific components: a base agent containing MDI and isocyanate group-terminated prepolymers with a polyol component having specific molecular weight characteristics. This composite approach allows the system to achieve both low viscosity and reduced elution by balancing the properties of individual components.
2Ease of operation
If the viscosity of the composition is lowered to improve penetrability, then the composition can easily penetrate fine gaps, but filling defects may occur during molding
Solution Approach 1:
The patent optimizes the viscosity parameter by controlling the molecular weight of the polyol (200-1000) and the NCO content of the base agent (10-30%). This parameter optimization ensures the composition has sufficiently low viscosity for penetration while maintaining appropriate rheological properties to prevent filling defects during molding.
Solution Approach 2:
The patent uses isocyanate group-terminated prepolymers that replicate the desired low-viscosity characteristics without the harmful side effects of excessive low-molecular weight product formation. These prepolymers serve as a refined copy of the ideal viscous properties needed for both penetration and defect-free molding.
3Productivity
If MDI monomer content is increased to improve reaction efficiency, then the curing speed increases, but the elution of low-molecular weight reaction products increases
Solution Approach 1:
The patent identifies and controls the MDI monomer content parameter, setting it at 35% by mass or less. This parameter control ensures that there is sufficient MDI for adequate curing speed while preventing excessive monomer that would lead to increased elution of low-molecular weight reaction products.
Solution Approach 2:
The patent establishes a feedback mechanism by specifying the MDI monomer content limit (35% or less) based on the observed relationship between monomer content and elution. This feedback loop ensures that formulation adjustments maintain both curing performance and low elution by monitoring and controlling the key parameter of MDI monomer content.
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 results in a polyurethane resin with low viscosity, rapid curability, and minimal elution of low-molecular weight products, enabling effective sealing and reducing defects in membrane modules.
Implementation Method 1
the isocyanate group-terminated prepolymer (A1-α) is a reaction product between an isocyanate group-containing compound (a1-α) and an active hydrogen-containing compound (a2-α)
Implementation Method 2
a composition for forming a polyurethane resin used for a membrane sealing material
Data Source
Figure 1
AI summary
Provided are a composition for forming a polyurethane resin used for a membrane sealing material, the composition having low viscosity and contributing to the formation of a membrane sealing material having reduced elution of low-molecular weight reaction products; and a membrane sealing material and a membrane module using this composition. Disclosed is a composition for forming a polyurethane resin used for a membrane sealing material, the composition including a base agent (A) and a curing agent (B), wherein the base agent (A) comprises an isocyanate group-terminated prepolymer (A1), the isocyanate group-terminated prepolymer (A1) is a reaction product between an isocyanate group-containing compound (a1) and an active hydrogen-containing compound (a2), the base agent (A) comprises diphenylmethane diisocyanate, the monomer content of the diphenylmethane diisocyanate is 35% by mass or less, and the curing agent (B) comprises a compound (b1) represented by Formula (1). In Formula (1), R represents an alkyl group having 2 or more carbon atoms.