UV-Cured Polyurethane Surface Skin for Low-Tack Leather-Like Sheets
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Solution Overview
Problem
Conventional leather-like sheets face issues with fuzz generation and poor surface quality due to surface tack, especially when using aqueous polyurethane resins, and existing non-solvent type hot-melt urethane resins struggle to maintain suppleness and bending resistance while preventing fuzz formation.
Innovation Solution
A leather-like sheet with a surface skin layer composed of a cross-linked polyurethane hot-melt composition containing a urethane prepolymer, a coloring agent, multi-functional (meth)acrylate, and a photopolymerization initiator, where the urethane prepolymer is modified with (meth)acrylate to introduce polymerizable unsaturated bonds for ultraviolet curing, reducing surface tack and enhancing curing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aqueous polyurethane resin is used to form the surface skin layer, then environmental friendliness is improved, but water resistance and durability deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the polyurethane resin by incorporating hydrophobic segments and controlling the NCO/OH ratio to achieve both environmental friendliness and water resistance simultaneously
Solution Approach 2:
The patent creates a composite resin system combining polyurethane with hydrophobic additives and cross-linking agents to achieve multiple properties (environmental friendliness, water resistance, durability) in a single material
2Productivity
If non-solvent type hot-melt urethane resin is used to form the surface skin layer, then manufacturing efficiency is improved, but surface tack and fuzz generation worsen
Solution Approach 1:
The patent adjusts the molecular weight, functional group content, and composition ratios of the hot-melt resin to control surface tack while maintaining manufacturing efficiency
Solution Approach 2:
The patent replaces the conventional thermal curing mechanism with a chemical cross-linking mechanism using isocyanate groups that react with hydroxyl groups, enabling curing without prolonged thermal exposure and reducing surface tack
3Productivity
If the surface skin layer is wound into a roll before complete curing, then manufacturing efficiency is improved, but fuzz generation and surface grade deteriorate
Solution Approach 1:
The patent applies a preliminary curing treatment before rolling to reduce surface tack sufficiently for handling, then completes the curing process after rolling to prevent fuzz generation during storage and transport
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 solution effectively suppresses fuzz generation, maintains excellent suppleness and bending resistance, and improves the surface grade of the leather-like sheet, making it suitable for applications in footwear, furniture, and clothing.
Implementation Method 1
a surface skin layer composed of a cross-linked product of a polyurethane hot-melt composition containing 100 parts by mass of a urethane prepolymer (A), 5 parts by mass to 40 parts by mass of a coloring agent (B) containing a polyol as a vehicle, 5 parts by mass to 50 parts by mass of multi-functional (meth)acrylate (C), and 0.5 parts by mass to 5 parts by mass of a photopolymerization initiator (D)
Data Source
AI summary
A leather-like sheet is provided having a substrate layer and a surface skin layer in which the surface skin layer is composed of a cross-linked product of a polyurethane hot-melt composition containing 100 parts by mass of a urethane prepolymer, 5 parts by mass to 40 parts by mass of a coloring agent containing a polyol, 5 parts by mass to 50 parts by mass of multi-functional (meth)acrylate, and 0.5 parts by mass to 5 parts by mass of a photopolymerization initiator, wherein the urethane prepolymer can be obtained by reacting 5% to 50% of the number of isocyanate groups in a urethane prepolymer containing isocyanate groups that is obtained by reacting a polyol containing 40% by mass or more of polytetramethylene glycol and a polyisocyanate with a (meth)acrylate containing a hydroxyl group. This leather-like sheet has an excellent surface grade while maintaining excellent suppleness and bending resistance.