Aqueous polyurethane dispersions for artificial leather applications
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Solution Overview
Problem
Current polyurethane artificial leather products face challenges in achieving a balance between mechanical properties, hydrolytic stability, cost, and manufacturing ease, with polyester polyol-based dispersions offering superior mechanical strength but at the cost of inferior hydrolytic stability and high manufacturing difficulty, while polyether polyol-based dispersions are hydrolytically stable but lack mechanical properties.
Innovation Solution
An aqueous polyurethane dispersion is developed, comprising a reaction product of a nonionic polyurethane prepolymer and a diamine chain extender, using a polyol mixture that includes random and/or block copolymers of propylene oxide and ethylene oxide, and poly(ethylene oxide) monols, with isophorone diisocyanate, to create polyurethane particles that combine the mechanical advantages of polyester polyol-based dispersions with the stability and cost-effectiveness of polyether polyol-based dispersions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester polyol-based dispersions are used to make polyurethane artificial leather, then mechanical properties (tensile strength, modulus, tear strength) are improved, but hydrolytic stability deteriorates and manufacturing difficulty increases
Solution Approach 1:
The patent uses a composite polyol system combining polyester polyol and polyether polyol in specific ratios (30-70 weight percent polyester, 70-30 weight percent polyether). This composite approach allows the final polyurethane dispersion to achieve both the mechanical properties from polyester polyol and the hydrolytic stability from polyether polyol, resolving the contradiction between strength and stability
Solution Approach 2:
The patent optimizes specific parameters including the polyester-to-polyether polyol ratio, prepolymer molecular weight (1000-10000 g/mol), isocyanate index (105-115), and chain extender type (diamine). By precisely controlling these parameters, the invention achieves a balance where mechanical properties are sufficient for artificial leather applications while hydrolytic stability is maintained through the polyether component
2Strength
If polyester polyol-based dispersions are used to make polyurethane artificial leather, then mechanical properties are improved, but manufacturing cost and difficulty increase due to high prepolymer viscosity
Solution Approach 1:
By combining polyester polyol with polyether polyol, the composite system achieves lower viscosity compared to pure polyester polyol systems with equivalent mechanical properties. The polyether component acts as a viscosity modifier, making the prepolymer easier to handle and process while maintaining sufficient mechanical performance through the synergistic effect of both polyol types
Solution Approach 2:
The patent controls prepolymer molecular weight within 1000-10000 g/mol and isocyanate index at 105-115, which optimizes the balance between viscosity and reactivity. These parameter controls ensure the prepolymer remains fluid enough for easy manufacturing while containing sufficient reactive groups to achieve the desired mechanical properties in the final product
3Reliability
If polyether polyol-based dispersions are used to make polyurethane artificial leather, then hydrolytic stability and manufacturing ease are improved, but mechanical properties deteriorate
Solution Approach 1:
The patent creates a composite polyol system where polyester polyol (30-70 wt%) provides the mechanical strength, tensile properties, and tear resistance, while polyether polyol (70-30 wt%) provides hydrolytic stability and processability. This composite formulation directly addresses the weakness of pure polyether systems by incorporating the mechanically superior polyester component
Solution Approach 2:
By optimizing the polyester polyol content to at least 30 weight percent of the total polyol mixture, the invention ensures sufficient mechanical properties are achieved. Simultaneously, maintaining polyether polyol at at least 70 weight percent ensures hydrolytic stability is preserved. This parameter optimization resolves the contradiction between mechanical performance and stability
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 resulting polyurethane dispersion exhibits tensile strength, tensile modulus, and tear strength comparable to polyester polyol-based products while retaining the hydrolytic stability and manufacturing ease of polyether polyol-based products, making it suitable for artificial leather and elastomeric coatings.
Implementation Method 1
The prepolymer is made by reacting one or more polyols with a polyisocyanate
Implementation Method 2
aqueous polyurethane dispersions are made by first preparing an isocyanate-terminated liquid prepolymer, dispersing that prepolymer into water
Implementation Method 3
reacting the prepolymer with a chain extender to produce the polyurethane particles
Implementation Method 4
Polyurethanes made by coagulating the dispersion of the invention exhibit properties
Data Source
AI summary
Aqueous polyurethane dispersions are useful for making artificial leather and similar products. The dispersions contain polyurethane-urea particles dispersed in an aqueous phase. The particles are made using isophorone diisocyanate, certain cyclic amine chain extenders and certain polyol mixtures.