Cellulose-Based Sheet with Thermoplastic Elastomer for Adhesion
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Solution Overview
Problem
Conventional methods for laminating cellulose-based films to polarizers face challenges such as film curling due to alkali treatment, long drying times for water-based adhesives, light sensitivity of UV adhesives, and alignment issues with pressure-sensitive adhesives, leading to adhesion failures and material damage.
Innovation Solution
A cellulose-based sheet laminate comprising a layer of cellulose-based material and a thermoplastic elastomer, specifically urethane or amide-based, with high light transmittance and excellent adhesiveness when thermally press-adhered, eliminating the need for alkali treatment, water-based adhesives, and UV-sensitive coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkali treatment is applied to saponify ester groups on the cellulose-based film surface, then adhesiveness is improved, but the film curls and becomes difficult to handle
Solution Approach 1:
The patent extracts and removes the problematic alkali treatment step from the process. Instead of applying chemical saponification that causes curling, the invention uses a cellulose-based film with inherently high adhesiveness that can be laminated without chemical modification, thereby eliminating the handling difficulty while maintaining bonding reliability
Solution Approach 2:
The invention changes the key parameter of adhesiveness from being achieved through chemical modification (alkali treatment) to being an inherent property of the cellulose-based film itself. This parameter change allows the film to maintain both high adhesiveness and flat, curl-free morphology during handling and lamination
2Reliability
If water-based adhesive is used for lamination, then adhesiveness is improved, but drying time becomes excessively long
Solution Approach 1:
The patent removes the water-based adhesive component from the lamination process entirely. The cellulose-based film is designed to exhibit high adhesiveness without requiring any external adhesive, thereby eliminating the lengthy drying period associated with water-based adhesive evaporation while maintaining strong bonding
Solution Approach 2:
The cellulose-based film serves its own adhesive function through its inherent surface properties. The film's own surface characteristics provide the necessary adhesion to bond with the polarizer, eliminating the need for separate adhesive application and drying steps
3Reliability
If UV-sensitive monomer composition is coated on the cellulose-based film, then adhesiveness is improved, but light shielding requirements increase process complexity
Solution Approach 1:
The patent removes the UV-sensitive monomer composition coating step from the process. The cellulose-based film provides inherent adhesiveness without requiring any UV-curable coating, thereby eliminating the need for light shielding measures and associated process complexity while maintaining strong bonding capability
Solution Approach 2:
The cellulose-based film's surface provides the adhesive function directly without requiring any additional UV-sensitive coating layers. This self-adhesive property eliminates the need for UV light shielding during storage and handling, significantly simplifying the overall process
4Reliability
If pressure-sensitive adhesive is used for lamination, then adhesiveness is improved, but alignment precision deteriorates due to film curvature
Solution Approach 1:
The patent removes the pressure-sensitive adhesive layer from the structure. The cellulose-based film itself provides the adhesive function through its inherent surface properties, and remains flat and free of curvature, enabling precise alignment during lamination without the handling difficulties associated with curved films
Solution Approach 2:
The invention changes the adhesive mechanism from pressure-sensitive chemical bonding to inherent surface adhesion of the cellulose-based film. This change allows the film to maintain a flat, stable morphology that facilitates precise alignment while still providing strong bonding capability
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 cellulose-based sheet exhibits excellent transparency and adhesiveness when thermally press-adhered, ensuring reliable lamination without curling, long drying times, or adhesion failures, and allows for precise alignment and strong bonding without material damage.
Implementation Method 1
Each of molecules forming the thermoplastic elastomer has both a rubber component having entropy elasticity and a molecule-constraining component for preventing plastic deformation
Implementation Method 2
The light transmittance of the sheet is 85% or more as determined with a transmittance of light having a wavelength of 380 to 780 nm
Implementation Method 3
bringing a cellulose-based film into close contact with a counterpart material such as a polarizer, followed by applying heat to adhere the film to the counterpart material
Data Source
AI summary
An object of the present invention is to provide a cellulose-based sheet which has excellent transparency, and exhibits excellent adhesiveness when thermally press-adhered. The sheet includes a laminate including a layer formed of a cellulose-based material and a layer formed of a thermoplastic elastomer. Each of molecules forming the thermoplastic elastomer has both a rubber component having entropy elasticity and a molecule-constraining component for preventing plastic deformation.