Optical Film Adhesive Layer Surface Smoothness
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Solution Overview
Problem
Existing methods for manufacturing optical film-forming pressure-sensitive adhesive layers using aqueous dispersion-type adhesives face challenges in achieving high surface smoothness without reducing productivity, such as coating speed, particularly in applications like liquid crystal display devices where visibility and optical properties are critical.
Innovation Solution
A method involving the application and controlled drying of an aqueous dispersion-type pressure-sensitive adhesive with specific viscosity and composition, including a (meth)acryl-based polymer, to achieve a surface roughness of 10-40 nm and haze of 1% or less, utilizing a two-step drying process and appropriate monomer units like alkyl(meth)acrylates and phosphate group-containing monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvent-type pressure-sensitive adhesive is used, then durability in heated or humid environments is improved, but surface smoothness is reduced due to uneven drying or air flow
Solution Approach 1:
The patent changes the solvent type from organic to aqueous dispersion, and controls the solid concentration (1-10% by weight) and viscosity (0.01-0.1 Pa·s at shear rate of 4000 l/s) to achieve both durability and surface smoothness. The aqueous dispersion formulation with specific parameters prevents uneven drying while maintaining adhesion performance.
2Manufacturing precision
If aqueous dispersion-type pressure-sensitive adhesive with low solid concentration is used, then surface smoothness is improved, but productivity is reduced due to lower coating speed
Solution Approach 1:
The patent optimizes the solid concentration to a specific range (1-10% by weight) and controls viscosity within 0.01-0.1 Pa·s at shear rate of 4000 l/s. This parameter optimization allows the aqueous dispersion to maintain surface smoothness while enabling high coating speeds of 10-100 m/minute, thus improving productivity.
Solution Approach 2:
The patent specifies viscosity at a particular shear rate (4000 l/s), indicating that the adhesive exhibits dynamic rheological properties. The viscosity is optimized to provide appropriate flow characteristics during high-speed coating while ensuring uniform drying and surface smoothness in the final layer.
3Productivity
If coating speed is increased to improve productivity, then surface irregularities increase due to uneven drying or air flow
Solution Approach 1:
The patent optimizes the formulation parameters (solid concentration: 1-10% by weight, viscosity: 0.01-0.1 Pa·s at shear rate of 4000 l/s) to enable high coating speeds (10-100 m/minute) while maintaining surface smoothness. The optimized parameters ensure uniform liquid flow and drying even at high speeds, preventing surface irregularities.
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 formation of a highly smooth and transparent pressure-sensitive adhesive layer that enhances visibility and maintains productivity, addressing the limitations of previous technologies by ensuring uniform liquid flow and reduced irregularities during the drying process.
Implementation Method 1
drying the applied aqueous dispersion-type pressure-sensitive adhesive
Data Source
AI summary
An object of the present invention is to provide a method for manufacturing an optical film-forming pressure-sensitive adhesive layer, which can reduce the problem with visibility without a reduction in productivity, such as a reduction in coating speed. A method for manufacturing an optical film-forming pressure-sensitive adhesive layer, comprising the steps of: (1) applying, to a release film, an aqueous dispersion-type pressure-sensitive adhesive including an aqueous dispersion containing a (meth)acryl-based polymer in the form of an aqueous dispersion; and (2) drying the applied aqueous dispersion-type pressure-sensitive adhesive, wherein the aqueous dispersion-type pressure-sensitive adhesive has a viscosity of 0.01 Pa·s to 0.1 Pa·s at a shear rate of 4,000 (l/s), the optical film-forming pressure-sensitive adhesive layer formed on the release film has a surface roughness (Ra) of 10 nm to 40 nm, and the optical film-forming pressure-sensitive adhesive layer has a haze of 1% or less.