Ohmic Heating of Coating Compositions for 28-Day Storage

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Solution Overview

Problem

Aqueous coating compositions are prone to microbial contamination during storage, which can lead to spoilage due to the limitations of conventional preservatives and the need to comply with biocide regulations, while existing heat treatment methods are inefficient for large volumes and cause damage or require special storage conditions.

Innovation Solution

A method involving ohmic heating of the coating composition to a temperature above 70°C for at least 1 second, followed by cooling, ensuring uniform heating and effective microbial kill without special storage conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional heat treatment methods (hot water or hot air) are used to pasteurise coating compositions, then microbial protection is achieved, but the heating is inefficient for large volumes and causes damage or requires special storage conditions

Engineering Contradiction:

Improvemicrobial protectionVSAvoidheating efficiency for large volumes

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces conventional mechanical heat transfer methods (hot water baths, hot air ovens) with microwave radiation heating. This substitution enables rapid and uniform heating of large volumes of coating composition throughout the entire batch, achieving pasteurisation temperatures efficiently without the volume limitations and damage risks associated with conventional methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the phase transition properties of water (from liquid to vapor) through microwave heating to achieve rapid temperature increase. The microwave energy causes water molecules to vibrate and generate heat, efficiently raising the temperature of large volumes to pasteurisation levels (above 70°C) within minutes, overcoming the slow heating rates of conventional methods

Inventive Principle:

Principle #36Phase transitions

2Reliability

If isothiazolinones are used as preservatives in waterborne coating compositions, then microbial protection is achieved, but skin sensitization risks increase and regulatory restrictions apply

Engineering Contradiction:

Improvemicrobial protectionVSAvoidskin sensitization

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies microwave pasteurisation as a preliminary treatment to coating compositions before packaging and storage. By killing microorganisms in advance through rapid heating to pasteurisation temperatures and holding for a specified time, the need for high concentrations of sensitizing preservatives like isothiazolinones is reduced, allowing use at or below skin sensitization concern thresholds while maintaining microbial protection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the typically harmful effect of heat (which can damage coating composition) into a beneficial pasteurisation process by using microwave radiation. This allows controlled, uniform heating that achieves microbial kill without the damaging effects of conventional high-temperature methods, enabling reduced preservative levels while maintaining stability

Inventive Principle:

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

3Reliability

If heat treatment by heat transfer (hot water or hot air) is used to pasteurise coating compositions, then microbial protection is achieved, but lag time increases as volume increases and internal temperature may not reach pasteurisation temperature

Engineering Contradiction:

Improvemicrobial protectionVSAvoidlag time to achieve pasteurisation temperature

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent employs microwave radiation that causes molecular vibration and rotation of water molecules in the coating composition. This internal vibration generates heat throughout the entire volume simultaneously, eliminating the lag time associated with conventional external heat transfer methods where heat must conduct from the outside inward, enabling rapid pasteurisation of large volumes

Inventive Principle:

Principle #18Mechanical vibration

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 achieves uniform and rapid heating of large volumes, effectively killing microbes, allowing the coating composition to be stored for at least 28 days at 15-40°C without additional environmental controls, maintaining composition integrity.

Implementation Method 1

heating the coating composition by ohmic heating

Methodology Applied

Scientific EffectOhmic heating: Joule Heating

Data Source

PatentEP4613821A1method

Publication Date: 2025.09.10 JOTUN AS

Figure 1

AI summary

The present invention provides a method of preparing a coating composition for storage in a container for at least 28 days, preferably at 15-40 °C, comprising: (i) providing said composition; (ii) heating said composition to a treatment temperature of greater than 70 °C by ohmic heating; (iii) holding said composition at said treatment temperature for at least 1 second; and (iv) cooling said composition; wherein said composition comprises a binder, water and optionally biocide.