Polycarbonate Optical Sheet Dye Aggregation Control

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Solution Overview

Problem

Existing optical sheets face challenges in preventing aggregation of light absorbing agents while maintaining sufficient strength, as the aggregation of dyes during molding can lead to reduced optical performance and strength issues.

Innovation Solution

The use of a polycarbonate with a viscosity average molecular weight of 23,000 to 27,500, combined with a specific wavelength absorption layer containing a light absorbing agent and ultraviolet absorbing agent, ensures sufficient mixing and prevents excessive aggregation during extrusion molding, thereby maintaining strength and optical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the molecular weight of the resin material is reduced to increase fluidity in molten state, then the mixing between resin material and dye is improved, but the strength after molding becomes insufficient

Engineering Contradiction:
Improvemixing between resin material and dyeVSAvoidstrength after molding
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molecular weight of the polycarbonate resin within the range of 20,000 to 30,000. This specific parameter range optimizes the balance between fluidity during extrusion molding (enabling thorough mixing with dye) and mechanical strength after molding, resolving the contradiction between ease of manufacture and strength

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If the fluidity of molten resin material is increased, then the aggregation of dye is suppressed during molding, but the strength after molding is reduced

Engineering Contradiction:
Improvesuppression of dye aggregationVSAvoidstrength after molding
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent uses parameter changes by setting the molecular weight of polycarbonate to 20,000-30,000, which provides optimal fluidity in molten state. This fluidity prevents dye aggregation during extrusion molding while maintaining sufficient strength in the final molded product, thus resolving the contradiction between ease of manufacture and strength

Inventive Principle:
Principle #35Parameter changes

3Strength

If the molecular weight of the resin material is increased, then the strength after molding is improved, but the fluidity in molten state is reduced making mixing difficult

Engineering Contradiction:
Improvestrength after moldingVSAvoidmixing between resin material and dye
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by defining a specific molecular weight range (20,000-30,000) for polycarbonate. This range ensures that the resin has sufficient strength after molding while maintaining adequate fluidity during extrusion molding for effective mixing with the light-absorbing agent, thereby resolving the contradiction between strength and ease of manufacture

Inventive Principle:
Principle #35Parameter changes

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

This approach effectively prevents the aggregation of light absorbing agents and ensures the optical sheet has sufficient strength and enhanced weather resistance, improving its overall performance and durability.

Implementation Method 1

an optical sheet that absorbs a specific wavelength range from incident light for the purpose of enhancing the contrast of a visual field or preventing glare

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

the specific wavelength absorption layer contains a polycarbonate as a main material and a light absorbing agent that absorbs light of a specific wavelength, out of light in a wavelength range of 350 nm or more and 740 nm or less

Methodology Applied
Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Data Source

PatentEP3982170B1Optical sheet and optical component
Publication Date: 2023.12.06 SUMITOMO BAKELITE CO LTD
  • EP3982170B1 patent drawingFigure 1~2
  • EP3982170B1 patent drawingFigure 3~4
  • EP3982170B1 patent drawingFigure 5~6

AI summary

An optical sheet of the present invention includes a specific wavelength absorption layer that contains a polycarbonate as a main material and a light absorbing agent that absorbs light of a specific wavelength out of light in a wavelength range of 350 nm to 740 nm, in which the polycarbonate has a viscosity average molecular weight Mv of 20,000 to 30,000. In addition, the specific wavelength absorption layer further includes an ultraviolet absorbing agent that absorbs light in a wavelength range of 100 nm to 420 nm.