Method for producing polyurethane foam sheet and method for producing synthetic leather
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Solution Overview
Problem
There is a demand for a polyurethane foam sheet with better texture and adhesion, particularly for use as an adhesive layer in synthetic leather, due to the increasing use of solvent-free moisture-curable hot melt urethane compositions.
Innovation Solution
A method involving the application of a moisture-curable polyurethane hot melt resin composition containing specific polyols and an amine catalyst with a foaming constant of 10 or more, followed by moisture-foaming with water vapor to create a polyurethane foam sheet, which is then used as an adhesive layer in synthetic leather production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a moisture-curable hot melt urethane composition is used to produce polyurethane foam sheet, then solvent-free and environmentally responsible production is achieved, but the texture of the foam sheet is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the polyol mixture by specifying particular types and ratios of polyols (polytetramethylene glycol, polycarbonate polyol, and polyol from alkylene oxide adduct of bisphenol A) to achieve both solvent-free production and improved foam sheet texture. This parameter optimization resolves the contradiction between environmental responsibility and product quality.
Solution Approach 2:
The invention uses a composite polyol system combining multiple types of polyols (polytetramethylene glycol, polycarbonate polyol, and polyol from alkylene oxide adduct of bisphenol A) with specific molecular weight ranges and ratios. This composite material approach enables simultaneous achievement of solvent-free formulation and enhanced foam texture through synergistic effects of different polyol components.
2Ease of manufacture
If conventional polyol composition is used in moisture-foaming process, then production is simplified, but adhesion and texture of the foam sheet are insufficient
Solution Approach 1:
The invention optimizes the molecular weight parameters and composition ratios of polyols in the mixture. Specifically, it controls the number-average molecular weights of polytetramethylene glycol (1,000-10,000) and polycarbonate polyol (1,000-10,000), and their respective ratios (20-90 mass% and 10-80 mass%). These parameter changes improve adhesion and texture while maintaining the simplicity of the moisture-foaming process.
3Manufacturing precision
If polyol composition with amine catalyst having foaming constant Kw of 10 or more is used, then foam sheet texture is improved, but production cost increases
Solution Approach 1:
The invention changes the catalyst selection parameter by specifying amine catalysts with foaming constant Kw of 10 or more (such as N,N,N′,N′-tetramethylethylenediamine with Kw=15.8, N,N,N′,N′-tetramethyl-1,3-propanediamine with Kw=12.5, or N,N,N′,N′-pentamethyldiethylenetriamine with Kw=159). This targeted parameter change achieves improved foam texture while controlling production cost through efficient catalysis.
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 method produces a polyurethane foam sheet with excellent texture and adhesion, suitable for use as an adhesive layer in synthetic leather, enhancing mechanical strength and flexibility.
Implementation Method 1
the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of 10 or more
Implementation Method 2
bringing the mixture in the sheet form into contact with water vapor to moisture-foam the mixture
Data Source
AI summary
A method for producing a polyurethane foam sheet, including applying, in sheet form, a mixture obtained by mixing a moisture-curable polyurethane hot melt resin composition (X) containing a urethane prepolymer (i), which is a reaction product between a polyol (A) and a polyisocyanate (B), with a polyol composition (Y) onto a substrate, and bringing the mixture in the sheet form into contact with water vapor to moisture-foam the mixture. The method for producing a polyurethane foam sheet is characterized in that the polyol (A) contains a polytetramethylene glycol or polycarbonate polyol (a1) and a polyol (a2) having a structure derived from an alkylene oxide adduct of bisphenol A, and the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of 10 or more.