Multi-block copolymer adhesive for optical durability
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Solution Overview
Problem
Synthesizing block copolymers with high molecular weight is challenging due to their inherent characteristics, which limits their application as durable pressure-sensitive adhesives, especially in optical members like polarizing plates, where temperature and humidity stability is crucial.
Innovation Solution
A multi-block copolymer with specific glass transition temperature ranges and crosslinkable functional groups is developed, comprising blocks with varying monomers to achieve microphase separation, enhanced cohesive strength, and durability, using a method involving controlled polymerization with catalysts and initiators to prevent termination and increase molecular weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block copolymer is synthesized to achieve high molecular weight, then durability and stability are improved, but synthesis difficulty increases
Solution Approach 1:
The patent divides the polymer structure into multiple blocks with different glass transition temperatures (first block: -10°C or less, second block: 50°C or more, third block: -10°C or less), creating a multi-block copolymer structure that achieves high molecular weight while maintaining synthesis control through segmented polymerization
Solution Approach 2:
The patent controls the glass transition temperatures of different blocks within specific ranges to achieve the desired balance between molecular weight and synthesizability, using parameter optimization to resolve the contradiction between durability and synthesis difficulty
2Reliability
If molecular weight is increased to ensure durability, then reliability is improved, but microphase separation structure formation becomes more difficult
Solution Approach 1:
The multi-block copolymer structure with distinct blocks of different glass transition temperatures promotes microphase separation even at high molecular weights, as each block tends to phase separate based on its thermal properties while maintaining overall structural integrity
Solution Approach 2:
The patent creates a composite polymer structure combining blocks with different glass transition temperatures (soft blocks with Tg ≤ -10°C and hard blocks with Tg ≥ 50°C), where the composite nature enables both high molecular weight and stable microphase separation
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 pressure-sensitive adhesive composition exhibits excellent durability and stability across temperature and humidity conditions, effectively applied to optical members like polarizing plates with improved physical and chemical crosslinking points.
Implementation Method 1
The multi-block copolymer having the first, second, and third blocks having a glass transition temperature within the range may have a suitable microphase separation structure in a pressure-sensitive adhesive
Implementation Method 2
The multi-block copolymer is a crosslinkable copolymer having a crosslinkable functional group... a crosslinkable functional group capable of reacting with at least a functional group of a multifunctional crosslinking agent
Data Source
AI summary
Provided are a multi-block copolymer, a pressure-sensitive adhesive composition, a method of preparing a multi-block copolymer, a pressure-sensitive adhesive polarizing plate, and a liquid crystal display device. The pressure-sensitive adhesive composition including the multi-block copolymer may have excellent durability regardless of a temperature and/or humidity. In addition, the method of preparing a multi-block copolymer may prepare a multi-block copolymer increased in molecular weight which is structurally controlled with a simple process using a compound containing at least two halogen atoms. Accordingly, when included in a pressure-sensitive adhesive resin, the multi-block copolymer may have excellent cohesive strength in the resin, and a network structure during curing, and thus, when applied to a pressure-sensitive adhesive composition, the multi-block copolymer may be usefully applied to an optical member due to excellent durability regardless of a temperature and humidity.