Electron Beam Coating Viscosity Control for Sag Prevention
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Solution Overview
Problem
Current automotive paint technologies face challenges in curing paint on intricate vehicle shapes without sagging and require baking steps that generate CO2 and consume significant energy, while active energy ray-curable paints struggle with viscosity and curing efficiency.
Innovation Solution
A method involving the application of an electron beam-curable composition with specific viscosity ranges, followed by drying and electron beam irradiation in an inert gas atmosphere to form a cured coating film, allowing for spray-coating and curing along complex shapes without sagging and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional active energy ray-curable paint is used to enable curing without baking, then energy consumption is reduced, but the paint cannot be cured on intricate shapes and sags after spray-coating due to low viscosity
Solution Approach 1:
The patent changes the viscosity parameter of the coating composition by controlling the molecular weight and functional group content of polyisocyanate additives. This allows the paint to maintain appropriate viscosity for spray-coating and prevent sagging while remaining curable by electron beams without baking, thus resolving the contradiction between energy reduction and curing quality on intricate shapes
Solution Approach 2:
The patent uses composite coating compositions containing specific combinations of polyisocyanates with controlled molecular weights and functional group contents, along with other coating ingredients. This composite approach enables the paint to achieve both spray-coatability and effective electron beam curing on intricate automotive shapes without sagging
2Ease of operation
If paint viscosity is reduced to enable spray-coating, then spray-coating is achieved, but sagging occurs after coating
Solution Approach 1:
The patent optimizes the molecular weight parameter of polyisocyanate additives within specific ranges (500-5000 for spray-coating compatibility, and 1000-10000 for sag prevention). This parameter control allows the coating to maintain stability and prevent sagging while remaining suitable for spray-coating operations
3Reliability
If baking step is used to cure paint, then curing is achieved, but CO2 is generated and energy cost increases
Solution Approach 1:
The patent replaces the thermal curing mechanism (baking) with electron beam irradiation curing. This substitution eliminates the need for high-temperature heating, thereby preventing CO2 generation from baking processes while maintaining effective curing of the coating on automotive parts
Solution Approach 2:
The patent employs electron beam irradiation in an inert or controlled atmosphere to cure the coating without requiring oxygen-dependent chemical reactions. This approach eliminates CO2 emissions associated with conventional thermal baking while achieving reliable curing effectiveness
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 method enables the production of a coated material that can be spray-coated without running, cured efficiently on intricate shapes, and reduces energy consumption by eliminating or minimizing the baking step, while maintaining excellent adhesion and surface smoothness.
Implementation Method 1
irradiating the substrate that has the coating film obtained in step (1) or the dry coating film obtained in step (2) with an electron beam in an inert gas atmosphere to form a cured coating film
Implementation Method 2
an electron beam-curable composition containing an ethylenically unsaturated group-containing compound
Implementation Method 3
drying the coating film obtained in step (1) to form a dry coating film when the electron beam-curable composition contains a volatile component
Data Source
AI summary
An object of the present invention is to provide a method for producing a coated material by using a composition that can be spray-coated, and that does not run downward after coating (i.e., rheology controllable). The method for producing a coated material includes step (1) of applying an electron beam-curable composition containing an ethylenically unsaturated group-containing compound to a substrate to form a coating film that has a surface viscosity of 1 Pa·s to 300 Pa·s as measured based on an electric-field pickup method, step (2) of drying the coating film obtained in step (1) to form a dry coating film when the electron beam-curable composition contains a volatile component, and step (3) of irradiating the substrate that has the coating film obtained in step (1) or the dry coating film obtained in step (2) with electron beams in an inert gas atmosphere to form a cured coating film.