Thermosetting Polyurethane Protective Film for Displays
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Solution Overview
Problem
Existing surface protective films for display surfaces face challenges in achieving excellent smoothness, light transmission, transparency, scratch resistance, weather resistance, and self-healing properties while maintaining a uniform thickness of 30 μm or more, as they often suffer from cloudiness and difficulty in forming thick coatings with required optical characteristics.
Innovation Solution
A surface protective film comprising three layers: a thermosetting polyurethane protective layer made from a polyether polyol, aliphatic isocyanate, and alcohol-based curing agent, a transparent substrate film, and a pressure-sensitive adhesive layer, with a thickness of 100 μm to 300 μm, and optionally featuring a mold release film and release film for enhanced handling and anti-glare properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a wet film formation method is used to form a soft resin layer with low surface tension components (fluorine-containing compound or siloxane bond compound), then the coating can be formed, but cloudiness occurs and it is difficult to form a uniform transparent coating with thickness of 30 μm or more
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating system by using a two-component polyurethane system (isocyanate component + polyol component) instead of conventional single-component or additive-based systems. This chemical parameter change enables the formation of thick, uniform, transparent coatings without cloudiness, as the reactive components cure to form a crosslinked network that maintains optical clarity while achieving the required thickness and mechanical properties.
2Strength
If the protective layer thickness is increased to 30 μm or more for better protection, then scratch resistance and self-healing properties improve, but optical characteristics deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of an isocyanate component and a polyol component that react to form a polyurethane protective layer. This composite approach allows the layer to achieve both high mechanical strength (scratch resistance) and good optical properties (light transmission) simultaneously, as the chemical reaction products provide both structural integrity and optical clarity even at thicknesses of 30 μm or more.
3Ease of repair
If a polyurethane including polycaprolactone polyol is used for self-healing properties, then self-healing ability improves, but hydrolyzability increases and weather resistance decreases
Solution Approach 1:
The patent changes the chemical parameter of the polyol component by selecting polyols with lower hydrolyzability (such as polyester polyols or polyether polyols with controlled molecular weight and structure) instead of polycaprolactone polyols. This parameter change maintains the self-healing capability through the polyurethane crosslinked network while significantly improving weather resistance by reducing susceptibility to hydrolytic degradation.
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 light transmission, transparency, scratch resistance, and self-healing properties, along with improved mechanical strength and anti-glare functionality, while allowing for continuous production and easy formation of irregularities on the protective layer, maintaining suitable optical characteristics and good writing and sliding properties.
Implementation Method 1
a protective layer made of a thermosetting polyurethane which is a cured product of a polyether polyol, an aliphatic isocyanate, an alcohol-based curing agent
Implementation Method 2
a non-amine catalyst
Implementation Method 3
a mold release film is laminated on a surface on the side of the protective layer and a release film is laminated on a surface on the side of the pressure-sensitive adhesive layer
Data Source
AI summary
The present invention addresses the problem of providing a surface protective film laminate, surface protective film and its producing method. The surface protective film which has excellent smoothness, light transmission properties, transparency, scratch resistance, weather resistance and self-healing properties. The present invention provides, as a solution, a surface protective film wherein three layers, namely, a protective layer, a transparent base film and a pressure-sensitive adhesive layer are laminated in this order, said protective layer being formed of a thermosetting polyurethane which is a cured product of a polyether polyol, an aliphatic isocyanate, an alcohol-based curing agent and a non-amine catalyst.