Polyurethane prepolymer, adhesive and synthetic imitation leather
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Solution Overview
Problem
Ordinary polyurethane prepolymers penetrate into porous substrates used for synthetic artificial leathers, leading to inadequate adhesion strength, and existing technologies do not effectively control curability to ensure good softness, cold-resistant flexibility, and workability in shaping complex forms.
Innovation Solution
A polyurethane prepolymer is developed by reacting a polyol containing specific polyether and polyester polyols with a polyisocyanate, optimizing the composition to achieve good softness, cold-resistant flexibility, and excellent curability, with a polyether polyol accounting for 30% or more, a polyester polyol with isophthalic and sebacic acid-derived structures contributing to a balanced molecular weight and structure, and a polyisocyanate with a specific equivalent ratio to hydroxyl equivalent ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an ordinary polyurethane prepolymer is applied to porous substrates, then the prepolymer penetrates into the substrate, but adhesion strength becomes insufficient
Solution Approach 1:
The invention changes the molecular weight parameter of the polyol component (using 10,000-100,000) and the NCO/OH ratio parameter (1.0-2.0) to optimize the prepolymer's viscosity and reactivity, reducing penetration while maintaining adhesion strength
Solution Approach 2:
The invention uses a composite polyol system combining polyether polyol and polyester polyol in specific ratios (30-70 wt% and 70-30 wt% respectively) to achieve balanced properties of penetration resistance and adhesion
2Ease of operation
If curability is controlled to secure curing time, then workability in shaping complicated forms is improved, but adhesion strength may be compromised
Solution Approach 1:
The invention optimizes the NCO/OH ratio parameter within 1.0-2.0 range to control the curing rate, providing sufficient open time for shaping while ensuring adequate crosslinking density for adhesion strength
Solution Approach 2:
The invention creates a dynamic curing process where the prepolymer maintains flexibility during shaping (securing curing time) and then develops full adhesion strength as curing progresses
3Loss of substance
If the polyol molecular weight is increased to reduce penetration, then softness and cold-resistant flexibility may deteriorate
Solution Approach 1:
The invention combines polyether polyol (providing cold-resistant flexibility) and polyester polyol (providing penetration resistance) in a balanced ratio to achieve both low penetration and maintained flexibility
Solution Approach 2:
The invention carefully selects the polyol molecular weight range (10,000-100,000) to balance penetration resistance with flexibility, avoiding excessive molecular weight that would harm softness
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 polyurethane prepolymer exhibits excellent adhesion, rapid curing, and maintains tackiness for sufficient bonding time, ensuring good softness, cold-resistant flexibility, and improved workability in forming synthetic artificial leathers.
Implementation Method 1
a polyurethane prepolymer produced by reacting a polyol and a polyisocyanate
Implementation Method 2
capable of reacting with water (moisture) existing in air or in a substrate to which it is applied, to form a crosslinked structure
Data Source
AI summary
A polyurethane prepolymer produced by reacting a polyol and a polyisocyanate, wherein the polyol contains a polyether polyol (A) in an amount of 30% by mass or more, a polyester polyol (B) containing an isophthalic acid-derived structure and a sebacic acid-derived structure as partial structures derived from a dibasic acid in an amount of 30% by mass or more, and a polyester polyol (C) containing only a sebacic acid-derived structure as a partial structure derived from a dibasic acid in an amount of 20% by mass or less, the number-average molecular weight of the polyether polyol (A) is 1100 to 2400, and the ratio of the isocyanate equivalent of the polyisocyanate to the hydroxyl equivalent of the polyol is 2.1 or less.