Urethane resin composition, leather-like sheet, and method for producing the leather-like sheet
Find Innovative SolutionsGenerate Solutions
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 nonionic emulsifier and an aqueous medium, with a urea linkage content of 0.3 mol/kg or less, which enhances thermal coagulation and resistance to discoloration, ensuring the resin remains adhered to the fiber base and provides flexibility and resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
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 impregnated into a fiber base and undergo thermal coagulation, 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 selecting specific raw materials: polyol with carboxyl group (a1-1), aromatic polyisocyanate (a2), and chain extender with amino group (a3), while controlling the urea linkage content to 0.3 mol/kg or less. This parameter optimization resolves the contradiction by achieving both discoloration resistance and resilience simultaneously
Solution Approach 2:
The patent creates a composite urethane resin system combining multiple components with specific functions: polyol (a1) providing structural backbone, aromatic polyisocyanate (a2) providing crosslinking capability, and chain extender (a3) providing flexibility. The controlled urea linkage content acts as a composite structure that balances stability and resilience
2Strength
If the urea linkage content in the urethane resin is increased to improve adhesion to the fiber base, then the resin adheres better during thermal coagulation, but the coating film becomes more prone to discoloration over time
Solution Approach 1:
The patent optimizes the urea linkage content parameter to 0.3 mol/kg or less, which is a critical threshold value. This parameter control achieves the optimal balance between adhesion strength and discoloration resistance, resolving the technical contradiction by identifying the precise parameter range where both requirements are satisfied
3Productivity
If conventional aqueous urethane resin compositions are used for impregnation and thermal coagulation, then the production process is simple and efficient, but the resulting leather-like sheets lack flexibility and have poor feeling
Solution Approach 1:
The patent modifies the chemical composition parameters of the urethane resin, specifically the types of polyol, polyisocyanate, and chain extender used, along with controlling the urea linkage content. These parameter changes maintain the simplicity and efficiency of the thermal coagulation process while significantly improving the flexibility and feeling of the final product
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 from the fiber base, forms a stable coating film resistant to discoloration, and imparts excellent flexibility and resilience to leather-like sheets, making it suitable for various applications such as artificial leather and synthetic leather.
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
Implementation Method 2
the 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)
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 nonionic emulsifier, and an aqueous medium, the urethane resin being produced by reacting a polyol including a polyol including a carboxyl group with an aromatic polyisocyanate and a chain extender, the content of urea linkage in the urethane resin 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.