Moisture-Curing Polyurethane Adhesive Bonding for Composite Parts

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Solution Overview

Problem

Existing methods for bonding plastically deformable rigid polyurethane foams to covering materials using moisture-curing polyurethane adhesives face limitations due to short processing times, storage stability issues, and the presence of toxic organotin compounds, as well as difficulties with silicate deposits from alkaline metal silicate solutions.

Innovation Solution

A method involving a moisture-curing polyurethane adhesive hardened by an alkaline, aqueous alkali metal solution without soluble silicates, which allows for catalyst-free bonding and improved mechanical properties of the composite parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If moisture-curing polyurethane adhesive with catalysts is used for bonding, then bonding speed is improved, but storage stability deteriorates and processing time is limited

Engineering Contradiction:

Improvebonding speedVSAvoidstorage stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent removes catalysts from the moisture-curing polyurethane adhesive formulation. By extracting the catalyst component, the adhesive maintains stability during storage and handling while still achieving proper curing when exposed to moisture in the environment, thus resolving the contradiction between bonding speed and storage stability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The adhesive system uses moisture from the ambient environment or from the substrates themselves as the curing agent. This self-service approach eliminates the need for external catalysts while maintaining reliable bonding performance, allowing the adhesive to cure at appropriate speeds under normal processing conditions without compromising storage stability.

Inventive Principle:

Principle #25Self-service

2Loss of time

If alkaline metal silicate solution is used to harden adhesive, then processing time is extended, but silicate deposits form on devices

Engineering Contradiction:

Improveprocessing timeVSAvoidsilicate deposits

Core Design Contradiction:

Loss of timeVSObject-generated harmful factors

Solution Approach 1:

The patent removes soluble silicate compounds from the alkaline metal solution used to harden the adhesive. By extracting the silicate component while retaining the essential alkaline properties, the system achieves proper adhesive hardening and extended processing time without generating the harmful silicate deposits that contaminate bonding devices.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potentially harmful effect of silicate deposits into a beneficial outcome by using an alternative alkaline solution composition. The modified solution provides the necessary pH conditions for adhesive hardening and extended processing time while eliminating the deposit formation problem, thus turning a harmful factor into a resolved issue.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If organotin compounds are used as catalysts in adhesive, then bonding performance is improved, but toxicological concerns arise

Engineering Contradiction:

Improvebonding performanceVSAvoidtoxicological concerns

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent removes organotin catalysts from the adhesive formulation. By extracting these toxic compounds, the system maintains bonding performance through alternative mechanisms (moisture-curing without catalysts) while eliminating the toxicological concerns associated with organotin compounds, thus protecting both workers and end-users.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces persistent toxic catalysts with a catalyst-free system that relies on environmental moisture for curing. This approach uses readily available moisture in the processing environment as the curing agent, eliminating the need for toxic organotin compounds while achieving reliable bonding performance without long-term toxicological concerns.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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

This approach extends processing time, enhances storage stability, eliminates toxicological concerns, and prevents difficult-to-remove silicate deposits, resulting in composite parts with improved mechanical properties and efficient production.

Implementation Method 1

a moisture-curing polyurethane adhesive being used as the adhesive, which is brought into contact with an alkaline, aqueous alkali metal solution is hardened

Methodology Applied

Scientific EffectMoisture-curing reaction: Chemical Bonding

Implementation Method 2

which is brought into contact with an alkaline, aqueous alkali metal solution is hardened

Methodology Applied

Scientific EffectAlkaline solution hardening: Chemical Bonding

Data Source

PatentEP2785756B1Composite parts containing plastically deformable polyurethane rigid foam, adhesive and covering material

Publication Date: 2018.08.01 BASF SE

AI summary

The present invention relates to a process for producing composite parts from a thermoformable rigid polyurethane foam and a covering material, in which a thermoformable polyurethane foam is provided and adhesively bonded to covering material, using a moisture-curing polyurethane adhesive as an adhesive which is cured by being contacted with an alkaline aqueous alkali metal solution. The present invention further relates to a composite part obtainable by such a process and to the use of such a composite part in motor vehicles.