Transparent Cellulose Substrate with Oxidized Carboxy Groups
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Solution Overview
Problem
Conventional transparent substrates made from cellulose fibers suffer from insufficient transparency, discoloration upon heating, low water resistance, dimensional instability due to moisture absorption, and variations in physical properties, making them unsuitable for practical applications such as protection films for polarizing plates.
Innovation Solution
A transparent substrate is developed by oxidizing polysaccharides to introduce carboxy groups, cross-linking the molecules, and incorporating functional groups like oxazoline and isocyanate, which results in a substrate with a low linear expansion coefficient, high light transmittance, and improved water resistance, achieved through a specific oxidation and fiberization process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional cellulose fiber forming method is used, then the substrate can be manufactured, but transparency is insufficient
Solution Approach 1:
The patent changes the chemical parameters of cellulose fibers by oxidizing them to introduce carboxy groups, transforming conventional cellulose into oxidized cellulose with improved transparency while maintaining the fibrous structure
Solution Approach 2:
The patent creates a composite material system by combining oxidized cellulose fibers with cross-linking agents (oxazoline or isocyanate groups), forming a composite that achieves both transparency and structural stability
2Reliability
If conventional cellulose fiber forming method is used, then the substrate can be manufactured, but water resistance is low causing swelling
Solution Approach 1:
The patent changes the chemical parameters of cellulose by oxidizing hydroxyl groups to carboxy groups, reducing the material's affinity for water and preventing swelling while maintaining structural integrity
Solution Approach 2:
The patent introduces cross-linking agents (oxazoline or isocyanate groups) as intermediaries that form bridges between cellulose chains, creating a network structure that resists water penetration and dimensional change
3Temperature
If conventional cellulose fiber forming method is used, then the substrate can be manufactured, but discoloration occurs by heat
Solution Approach 1:
The patent changes the chemical composition of cellulose by introducing carboxy groups through oxidation, which stabilizes the molecular structure against thermal degradation and prevents heat-induced discoloration
Solution Approach 2:
The patent uses cross-linking agents as thermal stabilizers that form a protective network, preventing direct thermal damage to cellulose chains and eliminating discoloration during heat treatment
4Strength
If conventional cellulose fiber forming method is used, then the substrate can be manufactured, but robustness is insufficient
Solution Approach 1:
The patent creates a composite material system combining oxidized cellulose with cross-linking agents, forming a reinforced network structure that simultaneously achieves high robustness and dimensional stability
Solution Approach 2:
The patent introduces cross-linking agents as structural intermediaries that form bridges between cellulose chains, creating a three-dimensional network that enhances both strength and stability
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 resulting substrate exhibits enhanced stability, robustness, and minimal variations in characteristics, maintaining transparency and water resistance, even after heat treatment, making it suitable for use in protection films for polarizing plates.
Implementation Method 1
oxidizing a polysaccharide to substitute a hydroxyl group and/or an aldehyde group with a carboxy group under a predetermined condition
Implementation Method 2
reacting carboxy groups and/or hydroxyl groups of the polysaccharide which has been oxidized under the predetermined condition together to cross-link the molecules
Data Source
AI summary
<Problem> The present invention provides a formed article which effectively utilizes a natural material and which has a low linear expansion coefficient, a high light transmittance and an appropriate level of moisture permeability. To be more specific, the present invention provides a transparent substrate which has a low linear expansion coefficient, a high light transmittance and an appropriate level of moisture permeability. <Solution> The transparent substrate includes at least an oxidized polysaccharide and has a linear expansion coefficient of 50 ppm/°C or less at a temperature in the range of 30-150 °C and a light transmittance of 70 % or more at a wavelength of 660 nm. In addition, its manufacturing method includes an oxidizing process in which a cellulose reacts with 2, 2, 6, 6-tetramethyl-1-piperidine-N-oxyl or its derivatives as a catalyst to be oxidized in water under the presence of a co-oxidizing agent, along with a fiberizing process in which the oxidized cellulose is fiberized in water to form a cellulose fiber, and a substrate-forming process in which a transparent substrate is formed from a cellulose dispersion liquid containing the cellulose fiber.