Polyurea Crystal Sag Control Agent for Automotive Coating
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Solution Overview
Problem
Current automotive coating technologies face challenges with sag resistance on non-horizontal surfaces and overspray issues when using high transfer efficiency applicators, leading to defects like nozzle line visibility and stripe overlap due to the limitations of rheology modifiers and particle size constraints.
Innovation Solution
A solvent-borne coating composition incorporating a polyurea crystal sag control agent with a melting point of 50°C to 150°C, used in conjunction with a high transfer efficiency applicator, which minimizes sag and overspray by maintaining a wet film thickness of at least 30 microns without visible sag and optimizing droplet size and placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional spray equipment is used to apply automotive coating, then a uniform high-quality coating can be produced in a relatively short time, but significant overspray occurs leading to material waste and disposal costs
Solution Approach 1:
The patent uses digital printing technology to create a precise template or mask that defines the exact areas requiring coating. This digital copy guides the application process, enabling high transfer efficiency applicators to deposit coating only where needed, eliminating overspray waste while maintaining production speed through automated digital guidance
Solution Approach 2:
The patent transitions from conventional spray parameters (broad jet, wide droplet size distribution) to digital printing parameters (precise droplet placement, uniform droplet size). By changing the application parameters from aerosol spray to controlled droplet ejection, the system achieves both high productivity and minimal material waste
2Adaptability or versatility
If multiple colors are applied to a vehicle body using conventional spray technology, then color patterns can be created, but masking and multiple paint operations are required which are time-consuming and labor-intensive
Solution Approach 1:
The patent uses digital printing to directly copy complex multi-color patterns onto the vehicle body in a single operation. The digital file contains all color information and placement data, eliminating the need for physical masking and multiple sequential spray operations, thereby dramatically reducing painting time while maintaining full multi-color versatility
Solution Approach 2:
The digital printing system serves multiple functions simultaneously: it acts as a pattern guide, color mixer, and precise application device. A single digital printing operation can apply multiple colors in their exact final positions, replacing what would traditionally require multiple specialized operations including masking, multiple spray passes, and mask removal
3Ease of operation
If ink jet inks with low viscosity are used in high transfer efficiency applicators, then the applicator can operate without clogging, but the coating lacks sufficient durability for automotive applications
Solution Approach 1:
The patent changes the viscosity parameter of the coating composition to a higher range (50-500 cP) while using high transfer efficiency applicators. This is achieved through specialized formulation that maintains flowability during application but provides sufficient film formation and durability after application, unlike conventional ink jet inks that require very low viscosity
Solution Approach 2:
The patent uses composite coating formulations that combine resins, crosslinkers, and functional additives to achieve both high viscosity (for durability) and compatibility with high transfer efficiency applicators. The composite material properties enable the coating to be applied via precision droplet ejection while maintaining automotive-grade durability requirements
4Stability of the object's composition
If rheology modifiers are added to coating composition for sag resistance, then sag control is improved, but particle size constraints cause nozzle line visibility and stripe overlap defects when using high transfer efficiency applicators
Solution Approach 1:
The patent changes the type and concentration of rheology modifiers used, selecting agents with specific molecular characteristics that provide effective sag resistance at low concentrations. This prevents the formation of large aggregates that would cause nozzle clogging and visible defects, while still achieving adequate sag control on vertical and overhead surfaces
Solution Approach 2:
The patent applies rheology modifiers in a localized manner within the coating formulation, using them specifically to control sag in the applied film without affecting the droplet ejection properties. The modifiers are distributed at the molecular level to provide uniform sag resistance across the coating while maintaining compatibility with precision droplet application
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 solution effectively prevents sag and overspray, reducing nozzle line and stripe overlap defects, while ensuring efficient application and high transfer efficiency, even on non-horizontal surfaces, by using a polyurea crystal sag control agent in the coating composition.
Implementation Method 1
at least one polyurea crystal sag control agent that is the reaction product of an amine and an isocyanate, that has a melting point of from about 50°C to about 150°C
Implementation Method 2
The energy to eject a drop of ink can be from a thermal resistor
Implementation Method 3
The energy to eject a drop of ink can be from a thermal resistor, a piezoelectric crystal
Implementation Method 4
The energy to eject a drop of ink can be from a thermal resistor, a piezoelectric crystal, acoustic or a solenoid valve
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A method includes applying a coating composition to a substrate through a high transfer efficiency applicator to form the coating layer on the substrate wherein a loss of volatiles is less than about 0.5 weight, and wherein the coating composition comprises: A. a resin comprising an acrylic, a polyester, or combinations thereof; B. a melamine cross-linker; C. an optional pigment; D. an organic solvent; and E. at least one polyurea crystal sag control agent that is the reaction product of an amine and an isocyanate, that has a melting point of from about 50°C to about 150°C, and that is present in an amount of from about 0.1 to about 4 weight percent based on a total weight of the coating composition; and wherein the coating composition has a wet film thickness of at least about 30 microns measured at about 45 degrees without visible sag.