Multilayer Coating Composition for Low-Energy Metal Foil Curing

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Solution Overview

Problem

Existing multilayer coating processes for packaging materials, such as coffee capsules and beverage containers, are not economically viable, lack mechanical and chemical stability, and do not provide an attractive appearance, especially for multicolor coatings.

Innovation Solution

A solvent-borne coating composition comprising 15-40 wt.% polyester resin, 5-15 wt.% guanamine formaldehyde resin, 22-72 wt.% solvents with a boiling point of 50-98°C, and a curing catalyst, applied in two layers with peak metal temperatures of up to 100°C and 200°C, respectively, to achieve a tack-free intermediate product and full cure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lacquer layer is fully cured (stoved) prior to the application of a next lacquer layer, then the coating achieves mechanical and chemical stability, but the process becomes lengthy and energy consuming

Engineering Contradiction:
Improvemechanical and chemical stabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The coating process is divided into multiple stages: first application of coating composition, then application of a second coating composition containing curing catalyst, and finally a single high-temperature curing step. This segmentation allows the curing reaction to be initiated at lower temperatures during intermediate stages and completed efficiently in a final stage, reducing overall energy consumption while ensuring proper curing.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second coating composition is applied containing a curing catalyst, which prepares the coating system for efficient curing. This preliminary action of introducing the catalyst before the final curing step enables the curing reaction to proceed more rapidly and at lower temperatures, reducing the energy required for the curing process.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a lacquer layer is fully cured (stoved) prior to the application of a next lacquer layer, then the coating achieves mechanical and chemical stability, but the process becomes lengthy

Engineering Contradiction:
Improvemechanical and chemical stabilityVSAvoidprocess duration
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The coating process is divided into multiple stages: first application of coating composition, then application of a second coating composition containing curing catalyst, and finally a single high-temperature curing step. This segmentation allows the curing reaction to be initiated at lower temperatures during intermediate stages and completed efficiently in a final stage, reducing overall time.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The second coating composition is applied containing a curing catalyst, which prepares the coating system for efficient curing. This preliminary action of introducing the catalyst before the final curing step enables the curing reaction to proceed more rapidly and at lower temperatures, reducing the time required for the curing process.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If conventional coating systems are used for multilayer coating, then the process can be simplified, but the resulting products are not economically attractive

Engineering Contradiction:
Improveprocess simplicityVSAvoideconomic attractiveness
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The invention changes the chemical parameters of the coating system by using a water-based coating composition containing polyester resin and guanamine formaldehyde resin, along with specific curing catalysts. This parameter change enables the coating to achieve proper curing at lower temperatures and shorter times, improving productivity and economic attractiveness while maintaining process feasibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The coating composition uses a composite material system combining polyester resin with guanamine formaldehyde resin (without polyester groups), along with curing catalysts and pigments. This composite approach creates a coating that cures efficiently under the proposed process conditions, enabling economical production of multilayer coated products.

Inventive Principle:
Principle #40Composite materials

4Reliability

If high quality multilayer coating is applied to achieve mechanical stability and food safety, then the coating performance is improved, but the cost increases

Engineering Contradiction:
Improvemechanical stability and food safetyVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the chemical parameters of the coating system by using a water-based coating composition containing polyester resin and guanamine formaldehyde resin, along with specific curing catalysts. This parameter change enables the coating to achieve proper curing at lower temperatures and shorter times, reducing energy consumption and manufacturing costs while maintaining food safety and mechanical stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The coating composition uses a composite material system combining polyester resin with guanamine formaldehyde resin (without polyester groups), along with curing catalysts and pigments. This composite approach creates a coating that cures efficiently under the proposed process conditions, enabling economical production of multilayer coated products that meet food safety and mechanical stability requirements.

Inventive Principle:
Principle #40Composite materials

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 method produces mechanically stable, food-safe, and attractively colored packaging with high gloss and equal coloration, suitable for deep drawing and other mechanical treatments, while being energy-efficient and cost-effective.

Implementation Method 1

a curing catalyst is present in the coating composition... the coated substrate is heated to a peak metal temperature of at least 200°C

Methodology Applied
Scientific EffectCuring reaction: Chemical Bonding

Implementation Method 2

from 22 - 72 wt.% solvents with an atmospheric pressure boiling point of 50 - 98 °C

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3898857B2Composition for applying a multilayer coating on a substrate
Publication Date: 2026.01.14 ACTEGA RHENANIA

AI summary

A solvent borne coating composition comprising: from 15 –40 wt.% of a polyester resin, from 5 –15 wt.% of a guanamine formaldehyde resin having no polyester groups, from 22 –72 wt.% solvents with a boiling point of 50 - 98 °C and a curing catalyst. The composition is advantageously used of the application of multiple coloured layers on a metal or metal alloy foil. After the application of the composition, the metal or metal alloy foil can be further processed.