Liquid-State Reactive Polyurethane Adhesive for Structural Woodwork

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Solution Overview

Problem

Conventional adhesives used in structural woodworking, such as phenol/resorcinol/formaldehyde resin and melamine/urea/formaldehyde resin, contain toxic formaldehyde and fail to meet stringent structural safety and environmental standards, while other adhesives like PVAc white glue and hot melt adhesives lack sufficient bonding strength and environmental friendliness.

Innovation Solution

A liquid-state reactive polyurethane adhesive is developed, comprising a polyurethane prepolymer blocked by an isocyanate group, obtained through a polymerization reaction involving a polyisocyanate, polyol, stabilizer, catalyst, and hydrophobic filler, with specific weight ratios and molecular weight ranges, providing improved bonding strength and environmental sustainability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If phenol/resorcinol/formaldehyde resin or melamine/urea/formaldehyde resin is used as adhesive, then bonding strength is improved, but toxicity increases due to formaldehyde content

Engineering Contradiction:

Improvebonding strengthVSAvoidformaldehyde toxicity

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and eliminates the harmful formaldehyde component from the adhesive system entirely, replacing it with isocyanate and polyol components that do not contain formaldehyde, thereby maintaining bonding strength while removing toxicity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a composite adhesive system comprising isocyanate, polyol, and various additives (catalysts, stabilizers, fillers) to create a multi-component reactive polyurethane adhesive that achieves both high bonding strength and environmental safety

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If PVAc white glue or hot melt adhesive is used, then environmental friendliness is improved, but bonding strength decreases and cannot satisfy structural safety standards

Engineering Contradiction:

Improveenvironmental friendlinessVSAvoidbonding strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The patent changes the chemical parameters of the adhesive by using reactive polyurethane chemistry with isocyanate groups that form strong covalent bonds, transforming the adhesive from physically bonding (like PVAc) to chemically bonding, thereby achieving both environmental friendliness and high bonding strength

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the phase transition of the isocyanate group during the curing process, where the liquid adhesive transitions to a crosslinked gel structure, providing both ease of application in liquid state and high strength after curing

Inventive Principle:

Principle #36Phase transitions

3Ease of manufacture

If conventional adhesive formulations are used, then manufacturing simplicity is maintained, but reliability under stringent structural safety standards deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstructural safety compliance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent performs preliminary stabilization of the isocyanate component and pre-mixing of the adhesive formulation to ensure consistent performance and reliability while maintaining manufacturing simplicity through standardized production processes

Inventive Principle:

Principle #10Preliminary action

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 adhesive achieves high bonding strength, low glue failure rates under various environmental conditions, and meets stringent building safety and environmental standards, making it suitable for structural woodworking without the use of formaldehyde or solvents, thus qualifying as an environmentally friendly building material.

Implementation Method 1

the polyurethane prepolymer is obtained by a polymerization reaction, a reactive monomer of the polymerization reaction includes a polyisocyanate, a polyol

Methodology Applied

Scientific EffectPolymerization reaction: Chemical Bonding

Implementation Method 2

The polyurethane prepolymer is blocked by an isocyanate group

Methodology Applied

Scientific EffectBlocking:

Implementation Method 3

a catalyst and a hydrophobic filler

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 4

a stabilizer, a catalyst and a hydrophobic filler

Methodology Applied

Scientific EffectStabilization:

Data Source

PatentUS11753494B2Liquid-state reactive polyurethane adhesive

Publication Date: 2023.09.12 EVERMORE CHEM IND

AI summary

The present disclosure provides a liquid-state reactive polyurethane adhesive, which includes a polyurethane prepolymer. The polyurethane prepolymer is blocked by an isocyanate group, and the polyurethane prepolymer is obtained by a polymerization reaction, a reactive monomer of the polymerization reaction includes a polyisocyanate, a polyol, a stabilizer, a catalyst and a hydrophobic filler. A functionality of the polyisocyanate is 2.4 to 3. A molecular weight of the polyol is 1000 to 8000, and the polyol has hydrolysis resistance. The stabilizer has a structure represented by formula (I). The catalyst has a structure represented by formula (II). Formula (I) and formula (II) are as defined in the specification.