Aqueous Basecoat Jet Disintegration for Overspray Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional coating methods in the automotive industry face inefficiencies, including overspray, streaky appearances, bubbling, and pinhole formation, particularly when using aqueous basecoat compositions, which affect the quality and appearance of coated surfaces.
Innovation Solution
An aqueous, one-pack coating composition is developed, comprising self- or externally crosslinkable polymers, polymeric surface-active agents, and organic rheology control agents, with specific viscosity and solids content ranges, and excluding platelet-shaped particulate materials, to create a jet that disintegrates into droplets at a controlled distance, ensuring optimal coating and minimizing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional atomizing methods (rotary atomizer, air atomizer, airless device) are used, then coating application is achieved, but overspray increases and application efficiency decreases
Solution Approach 1:
The coating composition jet is segmented into droplets through controlled disintegration at a specific distance from the application device, creating a distribution of droplet sizes that optimizes deposition efficiency and reduces overspray
Solution Approach 2:
The patent changes the physical parameters of the coating composition (viscosity between 500-2000 mPa·s, solids content between 10-20 wt.%) to control jet disintegration behavior and droplet formation, improving application efficiency and reducing overspray
2Manufacturing precision
If jet disintegration into droplets is forced by coupling vibrations, then droplet distribution is improved, but disintegration distance becomes insufficient
Solution Approach 1:
Vibrations are coupled to the coating composition jet to control disintegration into droplets, achieving uniform droplet distribution while maintaining adequate disintegration distance for proper coating application
Solution Approach 2:
The system dynamically balances jet velocity, vibration frequency, and disintegration distance to achieve optimal droplet formation, allowing the jet to disintegrate at the correct distance while maintaining precision droplet distribution
3Manufacturing precision
If continuous region of coating composition jet is used for coating, then coating result is improved, but application distance must be very small
Solution Approach 1:
The viscosity and solids content parameters of the coating composition are optimized to enable the jet to maintain its continuous structure over a longer distance while still achieving proper coating quality upon impact
4Object-affected harmful factors
If aqueous basecoat compositions are used, then environmental compatibility is improved, but storage stability decreases due to premature curing
Solution Approach 1:
A curing agent is introduced as an intermediary component that remains dormant during storage and only activates under specific conditions (temperature, humidity, or catalyst presence), preventing premature curing while maintaining environmental compatibility of the aqueous formulation
Solution Approach 2:
The pH value and ionic strength of the aqueous basecoat composition are controlled to stabilize the polymer and prevent premature crosslinking, while still allowing curing to proceed when applied to the substrate
5Manufacturing precision
If platelet-shaped particulate materials are included, then coating composition is enhanced, but streaky appearance and surface defects occur
Solution Approach 1:
Platelet-shaped particulate materials are removed from the coating composition to eliminate the source of streaky appearance and surface defects such as bubbling and pinhole formation
Solution Approach 2:
The coating composition is formulated with uniformly shaped particles (non-platelet morphology) that distribute more evenly in the aqueous medium, preventing the formation of surface defects and achieving a uniform coating appearance
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 composition achieves a sharp-edged pattern with minimal overspray and surface defects, providing a high-quality, uniform coating that is storage-stable and suitable for automotive applications without premature curing, ensuring improved appearance and efficiency.
Implementation Method 1
the coating composition jet initially has a continuous region in the jet direction until the jet reaches a disintegration distance, whereupon after the disintegration distance after emission from the application device, the coating medium jet then disintegrates naturally (by natural disintegration according to Rayleigh as is known) into droplets
Implementation Method 2
at least one polymeric surface-active agent
Implementation Method 3
at least one organic rheology control agent selected from the group consisting of (meth)acrylic acid-(meth)acrylate copolymer rheology control agents and polyurethane rheology control agents
Data Source
AI summary
The invention relates to an aqueous, one-pack coating composition comprising at least one polymer selected from the group consisting self-crosslinkable polymers and externally crosslinkable polymers; at least one crosslinking agent for crosslinking the at least one polymer, if the at least one polymer is an externally crosslinkable polymer; at least one polymeric surface-active agent, and at least one organic rheology control agent selected from the group consisting of (meth)acrylic acid-(meth)acrylate copolymer rheology control agents and polyurethane rheology control agents, wherein the total solids content of the coating composition is from 7.5 wt.-% to 11.5 wt.-%; the viscosity at 23 °C is from 2000 mPas to 12000 mPas at a shear rate of 0.1 s-1; the amount of the at least one polymeric surface-active agent is from 0.5 to 25 wt.-% based on the total solids content of the coating composition; the amount of the at least one organic rheology control agent is from 5 to 12 wt.-% based on the total solids content of the coating composition; and the coating composition does not contain platelet- shaped particulate material having a median particle size D50 (determined by laser diffraction) of 2 µm or more. The invention further relates to a method of producing a coating, preferably a multi-layer coating, making use of an application method wherein the coating composition is applied by a device producing a coating composition jet. Moreover, the invention relates to thus coated substrates.