Dimer Fatty Acid Diol Reaction Product for Basecoat Clearcoat Adhesion
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Solution Overview
Problem
Existing multicoat paint systems face adhesion issues between the basecoat and clearcoat, particularly when exposed to weathering, leading to blisters and swelling, which affects the durability and integrity of the coating.
Innovation Solution
A dimer fatty acid/dimer diol reaction product is used, with a specific molar ratio and molecular weight range, to enhance adhesion by accumulating at interfaces in aqueous systems, improving the bonding between the basecoat and clearcoat layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional basecoat materials are used in multicoat paint systems, then the coating process is simple and cost-effective, but adhesion between basecoat and clearcoat deteriorates after weathering exposure
Solution Approach 1:
The dimer fatty acid/dimer diol reaction product serves as an intermediary substance that accumulates at the interface between basecoat and clearcoat layers. This reaction product has specific molecular weight (1200-5000 g/mol) and acid number (0.1-10 mg KOH/g) properties that enable it to position itself at the interface, creating a transition zone that maintains adhesion under weathering conditions by mediating between the two coating layers.
Solution Approach 2:
The invention changes the chemical and physical parameters of the basecoat material by incorporating a specific reaction product with controlled molecular weight (1200-5000 g/mol), acid number (0.1-10 mg KOH/g), and number-average molecular weight characteristics. These parameter changes enable the basecoat to maintain stable adhesion properties after weathering exposure.
2Reliability
If conventional coating materials are used, then the formulation is simple, but blisters and swelling occur after weathering exposure
Solution Approach 1:
The dimer fatty acid/dimer diol reaction product acts as a mediator that prevents the formation of blisters and swelling by accumulating at the coating-substrate interface and between coating layers. This intermediary substance creates a stable transition zone that accommodates stress and prevents defect formation during weathering.
Solution Approach 2:
The invention creates a composite coating system by combining the dimer fatty acid/dimer diol reaction product with conventional basecoat and clearcoat materials. This composite structure, with its specific molecular weight range (1200-5000 g/mol) and controlled acid number (0.1-10 mg KOH/g), provides enhanced resistance to blistering and swelling.
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 dimer fatty acid/dimer diol reaction product significantly improves adhesion and reduces the occurrence of blisters and swelling, even after exposure to weathering, resulting in a more durable and stable multicoat paint system.
Implementation Method 1
The dimer fatty acid/dimer diol reaction product which is preparable by reacting (a) dimer fatty acids with (b) at least one dimer diol, where components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.3/1.7 and the resulting dimer fatty acid/dimer diol reaction product possesses a number-average molecular weight of 1200 to 5000 g/mol and an acid number
Data Source
AI summary
The present invention relates to a dimer fatty acid/dimer diol reaction product which is preparable by reacting (a) dimer fatty acids with (b) at least one dimer diol, where components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.3/1.7 and the resulting dimer fatty acid/dimer diol reaction product possesses a number-average molecular weight of 1200 to 5000 g/mol and an acid number <10 mg KOH/g. The invention further relates to a pigmented aqueous basecoat material which comprises this dimer fatty acid/dimer diol reaction product, and also to the use of said dimer fatty acid/dimer diol reaction product in pigmented aqueous basecoat materials. It relates, further, to a method for producing multicast paint systems, and also to the multicoat paint systems producible by means of said method. The present invention relates, furthermore, to the refinishing of defects on multicoat paint systems.