Dimer Fatty Acid Polymer for Basecoat 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, and there is a need for improved adhesion in both original and refinish automotive coatings.
Innovation Solution
A polymer is developed by reacting dimer fatty acids with polyethers of specific molecular weights and ratios, resulting in a polymer with improved adhesion properties that can be used in pigmented aqueous basecoat materials, enhancing the adhesion between the basecoat and clearcoat, as well as between the basecoat and original finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional basecoat materials are used in multicoat paint systems, then the coating process can be completed, but adhesion problems occur between basecoat and clearcoat especially after weathering exposure
Solution Approach 1:
The patent modifies the chemical composition parameters of the basecoat material by incorporating specific polymers with carboxylic acid groups (0.1-5% by weight) and polyester resins with controlled molecular weights and acid numbers. These parameter changes enhance chemical adhesion to the clearcoat layer while maintaining stability against weathering factors such as UV radiation, moisture, and temperature variations.
Solution Approach 2:
The invention creates a composite basecoat material system that combines conventional paint components with specifically selected polymers and resin additives. This composite formulation synergistically improves adhesion properties and weathering resistance, preventing the formation of blisters and swelling that occur with standard materials when exposed to environmental conditions.
2Reliability
If conventional basecoat materials are used for automotive refinish, then the refinish process can be completed, but adhesion problems occur between basecoat and original finish
Solution Approach 1:
The patent adjusts the chemical parameters of the basecoat material by incorporating polymers with specific functional groups that enhance bonding to existing paint surfaces. The carboxylic acid content (0.1-5% by weight) and acid number (10-100 mg KOH/g) are optimized to create strong chemical adhesion to the original finish, ensuring reliable refinish applications even on weathered or previously coated surfaces.
3Productivity
If basecoat and clearcoat are cured together, then the coating process is efficient, but blisters and swelling occur due to poor adhesion
Solution Approach 1:
The invention modifies the basecoat formulation with specific polymers and resin systems that maintain adhesion integrity during the combined curing process. The controlled acid number and molecular weight parameters ensure that the basecoat remains chemically stable and adhesive throughout the curing cycle, preventing the generation of blisters and swelling that would otherwise occur during simultaneous basecoat and clearcoat curing.
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 polymer significantly improves adhesion in multicoat paint systems, preventing or reducing blisters and swelling after exposure to weathering, and is effective in both OEM and refinish automotive applications.
Implementation Method 1
a polymer which is preparable by reacting (a) dimer fatty acids with (b) at least one polyether of general structural formula (I)
Data Source
AI summary
Disclosed is a polymer which is prepared by reacting(a) dimer fatty acids with(b) at least one polyether of general structural formula (I)where R is a C3 to C6 alkylene radical and n is selected accordingly such that said polyether has a number-average molecular weight of 450 to 2200 g/mol, components (a) and (b) are used in a molar ratio of 0.7/2.3 to 1.3/1.7, and the resulting polymer has a number-average molecular weight of 1500 to 5000 g/mol and an acid number <10 mg KOH/g. Also disclosed is a pigmented aqueous basecoat material which comprises this polymer, and the use of said polymer in pigmented aqueous basecoat materials. It further relates to a method for producing multicoat paint systems, and also to the multicoat paint systems producible by means of said method. Moreover, the present invention relates to the refinish of defect areas on multicoat paint systems.