Spray Gun Airflow Angle Optimization for Water-Based Coatings
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Solution Overview
Problem
Existing manual spray guns for water-based coating compositions, particularly isocyanate-curing two-component coatings, face challenges in achieving a high dry film thickness without surface defects like popping marks and air entrapment, which limits the coating's visual appearance and durability.
Innovation Solution
A spray gun design that optimizes airflow angles and atomizing air pressure to fan air pressure ratios, allowing for improved atomization and air release, with specific configurations of the fluid spray nozzle and air cap to direct atomization air at angles of 10 to 70 degrees and an atomizing air pressure to fan air pressure ratio of 0.1 to 10, ensuring a stable and homogeneous spray cone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If water-based coating compositions are applied at high film thickness to improve durability and coverage, then the coating provides better protection and coverage, but surface defects such as popping marks and air entrapment occur
Solution Approach 1:
The patent applies parameter changes by optimizing the atomizing air pressure to fan air pressure ratio (specifically 0.6 to 0.9) and adjusting the airflow angle (30 to 45 degrees) to improve atomization quality. These parameter adjustments enable the coating to be applied at higher film thicknesses (60-90 μm) while preventing surface defects like popping marks and air entrapment, thus resolving the contradiction between film thickness and surface quality.
2Manufacturing precision
If atomizing air pressure is increased to improve atomization quality, then spray pattern homogeneity improves, but energy consumption increases
Solution Approach 1:
The patent optimizes the atomizing air pressure to fan air pressure ratio within the range of 0.6 to 0.9 and sets the airflow angle between 30 to 45 degrees. This optimized parameter combination achieves homogeneous spray patterns and good atomization quality while avoiding excessive energy consumption, as the system operates at balanced pressure ratios rather than maximum pressures.
3Object-affected harmful factors
If airflow angle is increased to improve air release, then air entrapment reduces, but spray pattern control becomes difficult
Solution Approach 1:
The patent specifies an airflow angle range of 30 to 45 degrees, which is optimized to balance air release capability with spray pattern control. This angle range provides sufficient air release to prevent air entrapment and popping marks while maintaining manageable spray pattern control for the operator, resolving the contradiction between air release effectiveness and operational ease.
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 significantly improves the appearance of the coating film by reducing air entrapment and increasing the popping resistance up to a dry film thickness of 60-90 µm, surpassing the limitations of existing VOC compliant manual spray guns.
Implementation Method 1
a spray gun, specifically a manual spray gun for water-based coating compositions... fluid spray nozzle and air cap assembly is configured to direct an atomization air flow into the coating composition jet
Implementation Method 2
fluid spray nozzle and air cap assembly is configured to direct an atomization air flow... into the coating composition jet... providing a stable and homogeneous spray cone
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3B
AI summary
This invention is directed to a spray gun comprising a spray gun body (1), an air cap (2), a fluid spray nozzle (3) having a fluid tip (4) and at least one air distribution channel for atomizing air (8) and at least one air distribution channel for fan air (9), wherein the fluid spray nozzle and the air cap are configured to direct an atomization airflow at an angle of 10 to 70 degrees, preferably 15 to 60 degrees, preferably of 30 to 45 degrees (relative to the coating composition jet) into the coating composition jet, and the fluid spray nozzle and the air cap are configured to provide an atomizing air pressure to fan air pressure ratio (AA/FA) of 0.1 to 10, preferably 0.5 to 1.0, preferably of 0.6 to 0.9, preferably of 0.66 to 0.88. The invention is also directed to the use of the spray gun for applying water-based coating compositions, in particular water-based clear coat coating compositions. The invention is also directed to a method for producing a coating layer over a substrate with a coating composition. The invention is also directed to a method for applying a layer of a water-based coating composition onto a substrate by a spray gun.