Optical Layered Body Hard Coat Surface Roughness Blocking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical layered bodies for image display devices face issues with blocking resistance, marking trace resistance, and transparency due to their hard coat layers, which can stick together and exhibit uneven curing when exposed to UV light, leading to productivity decreases and optical property defects.
Innovation Solution
An optical layered body with a triacetyl cellulose substrate and a hard coat layer having specific fine surface roughness, containing a lubricant such as silica particles, and a (meth)acrylic polymer with controlled hydroxyl value and molecular weight, which prevents blocking and marking traces while maintaining high transparency and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coat layer is formed by applying a coating liquid containing polyfunctional monomers and curing by UV irradiation, then the hard coat layer provides protective properties, but the optical layered bodies easily stick to each other causing blocking phenomenon
Solution Approach 1:
The patent applies local quality by creating fine surface roughness (specifically controlling Rtm, R3z, and Rz parameters) in specific regions of the hard coat layer surface. This localized surface modification provides both the protective properties needed and the non-stick characteristics to prevent blocking between stacked optical layered bodies, resolving the contradiction between protection and productivity.
Solution Approach 2:
The patent utilizes a porous or micro-roughened surface structure in the hard coat layer. The fine surface roughness creates micro-scale pores and irregularities that reduce contact area between stacked components, preventing adhesion and blocking while maintaining the overall protective function of the hard coat layer.
2Extent of automation
If strong ultraviolet light is irradiated through a protective film with markings to form a polarizer, then the polarizer is processed, but unreacted monomers react differently causing cross-linked curing shrinkage and marking traces on the surface
Solution Approach 1:
The patent addresses marking trace resistance by creating uniform fine surface roughness across the hard coat layer surface. This consistent micro-structure ensures uniform UV light distribution and reaction conditions, preventing differential curing shrinkage that would otherwise cause marking traces to appear on the surface during polarizer processing.
Solution Approach 2:
The patent applies preliminary action by pre-forming the fine surface roughness structure in the hard coat layer before the polarizer processing step. This pre-established uniform surface structure ensures that when UV irradiation occurs through the protective film with markings, the reaction proceeds uniformly without creating visible traces, as the surface topology already provides consistent light scattering and reaction conditions.
3Ease of manufacture
If the hard coat layer is made of plastic material such as acrylic resin, then it provides coating flexibility, but the optical layered bodies are not easily separated when rolled or stacked
Solution Approach 1:
The patent resolves the contradiction between coating flexibility and separability by maintaining the acrylic resin material throughout the hard coat layer while introducing fine surface roughness only at the surface. This localized modification preserves the bulk material's coating flexibility and adhesion properties while the roughened surface provides release characteristics that enable easy separation when stacked or rolled.
Solution Approach 2:
The patent effectively creates a composite structure within the hard coat layer, combining the acrylic resin bulk material with a fine surface roughness layer. This composite approach allows the bulk to provide flexibility and adhesion for ease of manufacture, while the surface layer provides non-stick properties for separability, resolving the contradiction between these two manufacturing requirements.
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 provides excellent blocking resistance, prevents curling and damage, and ensures high pencil hardness and abrasion resistance, while maintaining excellent optical properties and transparency, making it suitable for high-definition displays.
Implementation Method 1
curing the dried coating film by UV irradiation
Data Source
AI summary
Provided is an optical layered body having excellent blocking resistance. The optical layered body includes a triacetyl cellulose substrate and a hard coat layer, the hard coat layer having fine surface roughness that has an average PV roughness Rtm of 2.2 to 11.5 nm, a base roughness depth R3z of 2.5 to 13.5 nm, and a ten-point average roughness Rz of 2.6 to 13.5 nm, and satisfy the relation Rtm<R3z≦Rz.