Polyester Polymer Basecoat Adhesion Weathering
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Solution Overview
Problem
Existing multi-layer paint systems face adhesion issues between the base coat and clear coat, particularly when exposed to weather, leading to problems like blisters and swelling, which affect the durability and appearance of painted surfaces.
Innovation Solution
A polymer is produced by reacting dimer fatty acids with a specific polyether, resulting in a polymer with a number-average molecular weight of 1500 to 5000 g/mol and an acid number less than 10 mg KOH/g, which is used in pigmented aqueous basecoats to improve adhesion between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional pigmented aqueous basecoat is applied to a substrate and cured with a clearcoat, then the coating process is completed efficiently, but adhesion problems arise between the base coat and clear coat, particularly when exposed to weather
Solution Approach 1:
The patent modifies the chemical composition parameters of the basecoat by incorporating specific polyester resins with controlled molecular weights (1,500-5,000 g/mol) and acid numbers (2-10 mg KOH/g). These parameter changes in the polymer structure improve the adhesion reliability between basecoat and clearcoat while maintaining the efficiency of the coating process
Solution Approach 2:
The patent creates a composite coating system by combining the conventional clearcoat material with a specifically formulated basecoat containing polyester resins, polyether polyols, and dimer fatty acids. This composite material approach enhances the interfacial adhesion properties between layers without compromising the overall coating process efficiency
2Ease of manufacture
If the coating system uses standard polymers, then the manufacturing process is simple, but blisters and swelling occur when exposed to weather conditions
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight (1,500-5,000 g/mol) and acid number (2-10 mg KOH/g) of the polyester resins. These controlled parameters prevent weather-induced degradation that causes blisters and swelling, while the manufacturing process remains straightforward using conventional esterification reactions of dicarboxylic acids with polyether polyols
Solution Approach 2:
The patent uses readily available, inexpensive starting materials including common dicarboxylic acids (adipic, succinic, glutaric), commercial polyether polyols, and dimer fatty acids. These materials can be procured easily and processed through simple esterification to create a durable polymer that resists weathering effects
3Device complexity
If existing polymers are used in the basecoat, then the formulation is straightforward, but adhesion to both substrate and clearcoat deteriorates over time
Solution Approach 1:
The patent develops a composite polymer formulation combining polyester resins with specific molecular weights and acid numbers, polyether polyols, and dimer fatty acids. This composite approach creates a multi-functional basecoat that simultaneously improves adhesion to both the substrate and clearcoat layers, achieving long-term reliability without significantly increasing formulation complexity
Solution Approach 2:
The patent optimizes key polymer parameters including molecular weight (1,500-5,000 g/mol), acid number (2-10 mg KOH/g), and the ratio of polyether polyol to dimer fatty acid. These controlled parameter changes enhance the polymer's adhesive properties over time while maintaining a relatively simple formulation and manufacturing process
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 enhances the adhesion properties of the paint system, preventing or reducing the occurrence of bubbles and swelling when exposed to weather, thereby improving the durability and appearance of the painted surfaces.
Implementation Method 1
a polymer that can be produced by reacting (a) Dimer fatty acids with (b) at least one polyether
Data Source
AI summary
The present invention relates to a polymer which is preparable by reacting (a) dimer fatty acids with (b) at least one polyether of the general structural formula (I) where R is a C3 to C6 alkylene radical and n correspondingly is selected such that said polyether possesses 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 possesses a number-average molecular weight of 1500 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 polymer, and to the use of said polymer in pigmented aqueous basecoat materials. It relates additionally 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 repair of defects on multicoat paint systems.