Polyurethane Adhesive Resin Composition for Heat-Resistant Laminates
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Solution Overview
Problem
Existing polyurethane-based adhesives suffer from issues such as air bubble inclusion due to poor wetting, leading to defects like floating and peeling during laminate shaping, which affect appearance and adhesion, especially under roll-to-roll processing and high-temperature aging conditions, increasing energy costs and reducing productivity.
Innovation Solution
A resin composition comprising a polyurethane resin with specific molecular structures and ratios of dicarboxylic acids and diols, combined with a polyisocyanate curing agent, to enhance adhesion, heat resistance, and wettability, forming a laminate with reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional polyurethane adhesives are used for bonding wood-based materials, then bonding strength can be achieved, but formaldehyde outgassing occurs and bonding reliability deteriorates in high-temperature/high-humidity environments
Solution Approach 1:
The patent uses a composite adhesive system combining polyurethane resin with isocyanate crosslinking agents. This composite approach allows the polyurethane to provide initial bonding while the isocyanate forms additional crosslinks, creating a dual-mechanism adhesive system that reduces formaldehyde outgassing while maintaining bonding reliability in harsh environments.
Solution Approach 2:
The patent modifies the chemical composition parameters of the adhesive by incorporating specific ratios of polyols, polyisocyanates, and crosslinking agents. By adjusting these compositional parameters, the adhesive achieves reduced formaldehyde emission while gaining enhanced resistance to high-temperature and high-humidity conditions through controlled crosslinking density.
2Productivity
If polyurethane resin and polyol are mixed in advance, then bonding speed improves, but storage stability deteriorates due to premature reaction
Solution Approach 1:
The patent divides the adhesive system into separate components that are applied in sequence rather than pre-mixed. The polyurethane resin is applied first to the substrate, followed by the polyol and crosslinking agents. This segmentation in time and space allows rapid bonding when components contact the substrate while maintaining storage stability by keeping reactive components separate during storage and handling.
Solution Approach 2:
The patent applies the polyurethane resin to the substrate in advance as a primer layer before applying the polyol and crosslinking agents. This preliminary action prepares the substrate surface and initiates the bonding process, allowing the subsequent components to react rapidly upon contact while the initial layer remains stable during the application sequence.
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 provides a laminate with improved adhesion, heat resistance, and wettability, minimizing defects like floating and peeling, even under shaping processes, ensuring a satisfactory appearance and reducing energy consumption.
Implementation Method 1
a condensation reaction between a polyol having a secondary hydroxyl group and a polyisocyanate, and wherein a polymer chain is constructed by repeating units of a unit structure derived from the condensation reaction between the isocyanate group and the hydroxyl group
Data Source
AI summary
There is provided a resin composition useful as a base resin of a polyurethane-based adhesive that makes it possible to form an adhesive layer excellent in adhesion and heat resistance, that is unlikely to cause a fault, such as floating and peeling, even when being subjected to shaping such as drawing and makes it possible to produce a laminate having a satisfactory appearance, and that is excellent in wettability to a substrate of a resin, a metal, or the like. The resin composition is a resin composition to be used as a base resin of an adhesive together with a curing agent, the resin composition being a resin composition for a polyurethane-based adhesive. The resin composition contains a polyol (A) containing 80% by mass or more of a polyurethane resin (c) having a constituent unit derived from a polyol containing a polyester polyol (a), wherein the polyester polyol (a) has a constituent unit derived from a dicarboxylic acid component containing benzene-o-dicarboxylic acid, the content of a terminal hydroxy group of the polyester polyol (a) is 0.1 to 2 mol/kg, and the content of a terminal hydroxy group of the polyurethane resin (c) is 0.04 to 0.4 mol/kg.