Two-Part Shimming Adhesive for Structural Gap Filling

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Solution Overview

Problem

Existing shimming methods are labor-intensive and require separate adhesives, as liquid shims do not bear structural loads, leading to inefficient manufacturing processes in industrial applications.

Innovation Solution

A two-part curable shimming adhesive comprising a multifunctional epoxy resin, difunctional epoxy resin, and a polyetheramine hardener, optionally with inorganic fillers and phosphoric acid ester, which can be mixed to form a composition that cures at ambient temperature, providing high peel strength and acting as both a shim and adhesive.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If liquid shims are used to fill gaps, then the shimming process becomes simpler and more adaptable to irregular interfaces, but the bondline does not reside in the primary load path and cannot bear structural loads

Engineering Contradiction:
Improveadaptability to irregular interfacesVSAvoidstructural load bearing capacity
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The patent combines the shimming function and adhesive function into a single material composition. The curable adhesive composition serves both as a liquid shim to fill irregular gaps and as a structural adhesive to bear loads, eliminating the need for separate shimming and bonding operations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The curable adhesive composition is designed to perform multiple functions: it acts as a liquid shim material to fill gaps of various shapes and sizes, provides adhesive bonding strength to reside in the primary load path, and offers peel strength to prevent delamination. This multi-functional material replaces traditional separate shimming and adhesiving materials.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Strength

If separate adhesives are applied after shimming, then structural bonding strength is achieved, but the manufacturing process becomes more complex and labor-intensive

Engineering Contradiction:
Improvebonding strengthVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent merges the shimming material and adhesive into a single curable adhesive composition. This eliminates the need for separate shimming and adhesiving steps, reducing manufacturing complexity while maintaining both gap-filling and bonding functions in one integrated process.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The curable adhesive composition serves as both the shimming material and the bonding adhesive, providing universal functionality that eliminates the need for multiple separate materials and application steps, thereby simplifying the overall manufacturing process.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If traditional shimming methods are used with visual inspection, then fit accuracy can be achieved, but the process is iterative and labor-intensive requiring multiple temporary assemblies

Engineering Contradiction:
Improvefit accuracyVSAvoidmanufacturing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the iterative mechanical trial-and-error shimming process with a chemical system. The curable adhesive composition is applied once, allows for positioning adjustments during its open time, and then cures to provide permanent fixation, eliminating the need for repeated disassembly and reassembly operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The curable adhesive composition provides a working period during which positioning adjustments can be made before final curing. This preliminary adjustable state allows fit accuracy to be achieved without requiring multiple iterative assemblies, as all adjustments can be made during the open time of the adhesive.

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 simplifies the manufacturing process by eliminating the need for separate adhesives, ensuring high peel strength and structural support, suitable for automotive, aerospace, and construction applications.

Implementation Method 1

a two-part curable shimming adhesive is provided. The adhesive comprises: a base part comprising: a multifunctional epoxy resin having an epoxide functionality of at least three; and a difunctional epoxy resin miscibly blended with the multifunctional epoxy resin; and a hardener part comprising a polyetheramine

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

either the base part or hardener part further comprises an inorganic filler present in an amount from 10 percent to 60 percent

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 3

a phosphoric acid ester

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentUS12486437B2Shimming adhesive
Publication Date: 2025.12.02 3M INNOVATIVE PROPERTIES CO

AI summary

Provided are two-part shimming adhesives comprising a base part and a hardener part that are curable upon mixing. The base part includes a multifunctional epoxy resin having an epoxide functionality of at least three, a difunctional epoxy resin miscibly blended with the multifunctional epoxy resin. The hardener part includes a polyetheramine. Either the base part or hardener part further comprises an inorganic filler present in an amount from 10 percent to 60 percent, relative to the overall weight of the two-part curable shimming adhesive, and a phosphoric acid ester. The shimming adhesive enables joints to be assembled in one step, providing a significant advantage to the user.