Coating Film Formation Using LCST Graft Copolymer Preheating
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Solution Overview
Problem
Conventional preheating processes in coating film formation methods do not effectively improve smoothness, distinctness of image, and luster of coating films, particularly when using a 3-coat 1-bake process that omits the bake-curing step for energy savings.
Innovation Solution
A method involving an aqueous coating composition with a graft copolymer having a main chain with a lower critical solution temperature (LCST) between 30 to 95°C and hydrophobic side chains, preheated between 60 to 100°C, followed by curing, which enhances film smoothness and luster.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional preheating processes are used to prevent popping, then moisture evaporation is achieved, but coating film smoothness, distinctness of image, and luster are not improved
Solution Approach 1:
The patent changes the chemical composition parameters of the coating material by incorporating a graft copolymer with specific properties (main chain with LCST and hydrophobic side chains). This parameter change in material composition enables the coating to maintain appropriate viscosity during preheating, preventing both popping and surface defects, thereby improving smoothness, distinctness of image, and luster while still preventing moisture-related harmful effects
Solution Approach 2:
The patent uses a composite polymer structure consisting of a main chain with lower critical solution temperature and hydrophobic side chains. This composite material structure provides dual functionality: the main chain responds to temperature changes to control viscosity and prevent popping, while the hydrophobic side chains contribute to surface quality and film formation, thereby simultaneously achieving popping prevention and improved coating film quality
2Manufacturing precision
If preheating temperature is increased to improve flowability, then coating uniformity improves, but sagging occurs
Solution Approach 1:
The patent introduces dynamic viscosity control through the graft copolymer's temperature-responsive behavior. The copolymer's viscosity changes dynamically with temperature due to the LCST mechanism, allowing the coating to maintain optimal flow characteristics during application and then stabilize to prevent sagging as temperature increases during preheating, thus achieving both coating uniformity and shape stability
Solution Approach 2:
The patent utilizes the temperature-dependent parameter change of the graft copolymer's solubility and viscosity characteristics. As temperature increases during preheating, the copolymer undergoes phase transition that dynamically adjusts the coating viscosity, enabling improved flowability for uniform coating while subsequently preventing sagging through increased viscosity at higher temperatures
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 achieves a coating film with excellent smoothness, distinctness of image, and luster by forming a network structure that maintains flowability and prevents sagging during preheating, resulting in improved film quality.
Implementation Method 1
a copolymer of monomer components comprising one or more N-substituted (meth)acrylamide compounds, the copolymer being a graft copolymer comprising (A) a main chain having a lower critical solution temperature T1 in water within the range of 30 to 95° C.
Implementation Method 2
The preheating process performed in the 3-coat 2-bake process and 3-coat 1-bake process forcibly evaporates water that is contained in the aqueous intermediate coating composition or aqueous base coating composition as a solvent.
Implementation Method 3
a copolymer of monomer components comprising one or more N-substituted (meth)acrylamide compounds, the copolymer being a graft copolymer comprising (A) a main chain having a lower critical solution temperature T1 in water within the range of 30 to 95° C., and (B) at least one hydrophobic side chain
Data Source
AI summary
An object of the present invention is to provide a method for forming a coating film that is capable of forming a coating film having excellent smoothness, distinctness of image and luster using an aqueous coating composition. The present invention provides a method for forming a coating film comprising:Step (1): forming an uncured coating film by applying to a substrate an aqueous coating composition that contains a copolymer of monomer components comprising one or more N-substituted (meth)acrylamide compounds, the copolymer being a graft copolymer comprising (A) a main chain having a lower critical solution temperature T1 in water within the range of 30 to 95° C., and (B) at least one hydrophobic side chain;Step (2): preheating the uncured coating film formed in Step (1) under heating conditions such that a preheating temperature T2 falls within the range of 60 to 100° C., and the preheating temperature T2 and the lower critical solution temperature T1 have a relationship represented by the formula T2−T1=−30 to 30° C.; andStep (3): curing the uncured coating film formed in Step (2) by heating.