Leather-Like Sheet Urethane Composition for Color-Stable Flexibility
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Solution Overview
Problem
Aqueous urethane resin compositions used for producing leather-like sheets tend to discolor over time and lack resilience and flexibility, leading to a poor feeling and detachment from the fiber base during thermal coagulation.
Innovation Solution
An aqueous urethane resin composition is developed, comprising a urethane resin produced by reacting a polyol with a carboxyl group and an aromatic polyisocyanate, along with a chain extender, with a urea linkage content of 0.3 mol/kg or less, and a nonionic emulsifier, which enhances thermal coagulation and resistance to discoloration, ensuring the resin remains attached to the fiber base and provides flexibility and resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an aqueous urethane resin composition including a polyol with a carboxyl group, an alicyclic polyisocyanate, and a chain extender with an amino group is used, then the composition can be thermally coagulated to enhance flex resistance, but the coating film becomes discolored with time and lacks resilience
Solution Approach 1:
The patent changes the chemical parameters of the urethane resin by controlling the types and amounts of polyols, polyisocyanates, and chain extenders used in the reaction. Specifically, it uses a polyol with a carboxyl group, an aromatic polyisocyanate, and a chain extender with an amino group in controlled proportions to achieve a urea linkage content of 0.3 mol/kg or less, which prevents discoloration while maintaining flex resistance
Solution Approach 2:
The patent creates a composite urethane resin system by combining multiple components: a polyol (with carboxyl group), an aromatic polyisocyanate, and a chain extender (with amino group). This composite approach allows the resin to achieve both thermal coagulation capability for flex resistance and low urea linkage content for color stability
2Strength
If the urea linkage content in the urethane resin is increased to improve adhesion to the fiber base, then the resin attaches better, but the coating film loses flexibility and resilience
Solution Approach 1:
The patent precisely controls the urea linkage content parameter to be 0.3 mol/kg or less by adjusting the reaction conditions and component ratios. This parameter control ensures adequate adhesion to the fiber base while preserving the flexibility and resilience of the coating film, avoiding the paper-like feel associated with higher urea linkage content
3Strength
If thermal coagulation is performed to enhance the feeling of the leather-like sheet, then flex resistance improves, but the resin detaches from the fiber base during coloring
Solution Approach 1:
The patent optimizes the chemical composition parameters of the aqueous urethane resin, specifically controlling the urea linkage content to 0.3 mol/kg or less and using specific component ratios. This creates a resin that undergoes effective thermal coagulation to improve flex resistance while maintaining reliable attachment to the fiber base during subsequent coloring processes
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 effectively prevents detachment, maintains color stability, and imparts excellent flexibility and resilience to the coating film, making it suitable for leather-like sheets and other applications.
Implementation Method 1
performing thermal coagulation of the urethane resin composition in order to enhance the flex resistance and feeling of the leather-like sheets
Data Source
AI summary
Provided is an aqueous urethane resin composition with which a fiber base can be impregnated, which is capable of thermal coagulation, which does not detach from the fiber base due to water or heat in the step of coloring the impregnated base, and which is capable of forming a coating film having resistance to discoloration which may occur with time and an excellent feeling, that is, flexibility and resilience. The aqueous urethane resin composition includes a urethane resin (A), a nonionic emulsifier (B), and an aqueous medium (C), one urethane resin (A) being produced by reacting a polyol (a1) including a polyol (a1-1) including a carboxyl group with an aromatic polyisocyanate (a2) and a chain extender (a3), the content of urea linkage in the urethane resin (A) being 0.3 mol/kg or less. Also provided is a leather-like sheet produced by impregnating a fiber base with the aqueous urethane resin composition and subsequently performing thermal coagulation of the urethane resin composition.