Sheet material and method for producing same
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Solution Overview
Problem
Existing sheet materials produced using water-dispersed polyurethane tend to have a hard texture due to dense adhesion between the fibrous base material and the polyurethane, lacking flexibility, chemical resistance, and dyeing resistance compared to organic solvent-based polyurethane systems.
Innovation Solution
A sheet material is developed with an elastomer and a fibrous base material comprising ultrafine fibers, where the elastomer has a hydrophilic group and N-acylurea or isourea bonds. The production method involves a first elastomer precursor impregnation step, an ultrafine fiber generating step, and a second elastomer impregnation step, with specific conditions to achieve improved flexibility, chemical resistance, and dyeing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-dispersed polyurethane is used to impregnate fibrous base material, then environmental harm is reduced, but the sheet material becomes hard and loses flexibility
Solution Approach 1:
The invention changes the molecular structure parameters of the polyurethane elastomer by introducing hydrophilic groups and specific chemical bonds (N-acylurea and isourea bonds). This structural modification allows the polyurethane to form a less dense, more flexible coating that maintains softness while using water as a dispersant instead of organic solvents, thus resolving the contradiction between environmental friendliness and flexibility
Solution Approach 2:
The invention creates a composite structure by combining polyurethane elastomer with hydrophilic groups and specific chemical bonds within the molecular chain. This composite molecular structure enables the material to simultaneously achieve environmental compatibility (water dispersibility) and mechanical flexibility, overcoming the hardness problem associated with conventional water-dispersed polyurethane
2Object-affected harmful factors
If water-dispersed polyurethane is used for impregnation, then organic solvent usage is eliminated, but chemical resistance deteriorates
Solution Approach 1:
The invention modifies the chemical structure parameters of polyurethane by incorporating N-acylurea bonds and isourea bonds, which enhance chemical resistance. These structural changes allow the water-dispersed polyurethane to withstand chemical environments better, thus improving reliability while maintaining the environmental benefit of eliminating organic solvents
3Object-affected harmful factors
If water-dispersed polyurethane is used for impregnation, then organic solvent usage is eliminated, but dyeing resistance deteriorates
Solution Approach 1:
The invention changes the molecular parameters of polyurethane by introducing hydrophilic groups and specific chemical bonds that affect dye interaction. These structural modifications enable the water-dispersed polyurethane to provide better dyeing resistance while maintaining environmental friendliness and eliminating organic solvent usage
4Strength
If dense adhesion between fibrous base material and polyurethane is achieved, then bonding strength is improved, but flexibility is reduced
Solution Approach 1:
The invention changes the adhesion mechanism parameters by modifying the polyurethane molecular structure with hydrophilic groups and specific bonds. This creates a bonding interface that provides sufficient strength while maintaining flexibility, resolving the contradiction between bonding strength and flexibility in water-dispersed polyurethane systems
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 sheet material exhibits enhanced flexibility, chemical resistance, and dyeing resistance, with reduced fiber fragments during washing, maintaining its appearance and properties even after exposure to solvents or harsh environments.
Implementation Method 1
the elastomer has a hydrophilic group and N-acylurea bonds and/or isourea bonds
Implementation Method 2
a so-called wet heat solidification method in which a hydrated state of a water-dispersed polyurethane dispersion is collapsed by heating and polyurethane emulsions are aggregated to be solidified
Data Source
AI summary
The sheet material according to the present invention has a polymer elastic body and a fibrous base material comprising ultrafine fibers, wherein the average single fiber diameter of the ultrafine fibers is 0.1 μm to 10.0 μm, the polymer elastic body has a hydrophilic group and an N-acylurea bond and/or an isourea bond, and the following conditions are satisfied: the longitudinal stiffness, in accordance with method A (45° cantilever method) in the text of “8.21 Stiffness” of JIS L 1096:2010 “Testing Methods for Woven and Knitted Fabrics”, is 40 mm to 140 mm; and after immersion for 24 hours in N,N-dimethylformamide, the following are obtained in wear testing using a pressing load of 12.0 kPa and 20,000 friction cycles in accordance with method E (Martindale method) in the text of “8.19 Wear Strength and Friction Discoloration” of JIS L 1096:2010 “Testing Methods for Woven and Knitted Fabrics”: a grade of at least 4 and a wear loss of not more than 25 mg.