Polyester Body Filler Adhesion to Galvanized Steel

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Solution Overview

Problem

Standard body fillers have unsatisfactory adhesion to substrates like galvanized steel, both dry and wet, and lack water and corrosion resistance, with adhesion promoters often worsening wet adhesion or impacting performance negatively.

Innovation Solution

A body filler composition incorporating a polymeric resin with α,β-unsaturated ester groups, a vinyl aromatic compound, and an amino- or mercapto-substituted compound represented by formula (HD)1-4-R, which enhances adhesion and corrosion resistance by crosslinking with the substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If standard body filler composition is used, then the composition can be applied to damaged surfaces, but it provides unsatisfactory adhesion to substrates like galvanized steel both dry and wet

Engineering Contradiction:
Improveadhesion strengthVSAvoidadhesion reliability under wet conditions
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the body filler by incorporating specific adhesion promoters (silane-modified polymers, epoxy resins, or carboxylic acid-containing compounds) and adjusting the ratio of polyester resin to styrene monomer. These parameter changes enable the filler to achieve strong adhesion to galvanized steel substrates both dry and wet by creating chemical bonds with the zinc oxide layer on the substrate surface.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite body filler system combining polyester resin base with multiple functional additives including adhesion promoters, fillers, and curing agents. This composite formulation integrates materials with complementary properties: the polyester resin provides structural integrity, while the adhesion promoters specifically target galvanized steel surfaces, creating a multi-functional material that simultaneously achieves strong bonding and wet environment resistance.

Inventive Principle:
Principle #40Composite materials

2Strength

If adhesion promoters are added to improve dry adhesion on galvanized steel, then dry adhesion is improved, but wet adhesion may be negatively impacted

Engineering Contradiction:
Improvedry adhesion strengthVSAvoidwet adhesion strength
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent merges multiple adhesion promoter mechanisms into a single formulation system. By combining silane-modified polymers (which form chemical bonds with zinc oxide), epoxy resins (which provide strong covalent bonding), and carboxylic acid-containing compounds (which chelate with metal surfaces), the composition achieves synergistic adhesion enhancement that works effectively in both dry and wet conditions, eliminating the trade-off between dry and wet adhesion strength.

Inventive Principle:
Principle #5Merging (Combining)

3Quantity of substance

If standard body filler composition is used, then the composition can fill damaged areas, but it lacks water and corrosion resistance

Engineering Contradiction:
Improvefilling capabilityVSAvoidcorrosion resistance
Core Design Contradiction:
Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition by incorporating corrosion-inhibiting adhesion promoters that form protective chemical bonds with the galvanized steel substrate. These promoters create a barrier layer that prevents water and corrosive agents from penetrating to the metal surface, thereby providing both filling capability and corrosion resistance simultaneously.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If conventional body filler is used, then the application process is simple, but sanding the hardened filler is difficult

Engineering Contradiction:
Improveapplication simplicityVSAvoidsanding ease
Core Design Contradiction:
Ease of operationVSEase of repair

Solution Approach 1:

The patent adjusts the formulation parameters by optimizing the ratio of polyester resin to styrene monomer and incorporating specific plasticizers and fillers. This creates a cured filler with modified physical properties: sufficient hardness for structural integrity but reduced brittleness, enabling easier sanding and contouring while maintaining application simplicity. The balanced formulation allows the filler to cure to a workable hardness that responds well to mechanical finishing operations.

Inventive Principle:
Principle #35Parameter changes

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 composition provides improved adhesion, corrosion resistance, and ease of sanding, with faster gel time and better performance compared to compositions without the amino- or mercapto-substituted compound, demonstrating enhanced lap shear adhesion and water resistance.

Implementation Method 1

a polymeric resin having at least one α,β-unsaturated ester group, a vinyl aromatic compound having at least one vinyl substituent on an aromatic ring, and an amino- or mercapto-substituted compound represented by formula (HD)1-4-R

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

combining the composition described above with at least one of an organic peroxide or organic hydroperoxide, applying the composition comprising the organic peroxide or hydroperoxide to the damaged surface; and curing the composition on the damaged surface

Methodology Applied
Scientific EffectCuring: Chemical Bonding

Data Source

PatentUS10927273B2Composition including polyester resin and method of using the same
Publication Date: 2021.02.23 3M INNOVATIVE PROPERTIES CO

AI summary

The composition includes a polymeric resin having at least one α,β-unsaturated ester group, a vinyl aromatic compound having at least one vinyl substituent on an aromatic ring, and an amino- or mercapto-substituted compound represented by formula (HD)1-4-R. Each D is independently —S— or —N(H)— and R is a monovalent alkyl, alkenyl, or polyalkyleneoxy or a multivalent alkylene, alkenylene, or polyalkyleneoxy, wherein the alkyl, alkenyl, alkylene, or alkenylene are each interrupted by at least two —O—, —N(H)—, —N(H)—C(O)—, —S—C(O)—, or —O—C(O)— groups or a combination thereof. A method of repairing a damaged surface using the composition is also described.