Void-Containing Layer Laminate Adhesive Penetration
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Solution Overview
Problem
The challenge is to create a laminate of a void-containing layer and a pressure-sensitive adhesive layer that balances adhesive force with the prevention of adhesive penetration into voids, particularly in high-temperature environments, while maintaining optical characteristics.
Innovation Solution
A laminate is developed with a void-containing layer and a pressure-sensitive adhesive layer, where the adhesive layer is directly laminated on the void-containing layer, having a void fraction of 35 vol % or more, and a gel fraction of 70% or more, with specific polymer and crosslinking agent compositions, and a thickness of 2 to 50 μm, satisfying the equation (100−X)/100 × Y ≤ 10, where X is the gel fraction and Y is the thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a pressure-sensitive adhesive with high elastic modulus (hard adhesive) is used to prevent penetration into voids, then adhesive penetration is reduced, but pressure-sensitive adhesive force is lowered
Solution Approach 1:
The patent changes the molecular weight parameter of the pressure-sensitive adhesive polymer to a specific range (100,000 to 500,000) to achieve optimal balance between penetration resistance and adhesive force. This parameter optimization allows the adhesive to have sufficient viscosity to resist penetration while maintaining adequate adhesive strength through controlled molecular characteristics.
Solution Approach 2:
The patent creates a composite adhesive system by combining pressure-sensitive adhesive with specific functional additives including UV curable monomers and phot initiators. This composite formulation enables the adhesive to exhibit dual characteristics: resistance to penetration under normal conditions and controlled curing properties for strong bonding, thus resolving the contradiction between hardness and adhesive force.
2Strength
If a pressure-sensitive adhesive with low elastic modulus (soft adhesive) is used to achieve high adhesive force, then adhesive force is improved, but penetration into voids increases
Solution Approach 1:
The patent optimizes the molecular weight parameter within the range of 100,000 to 500,000 to achieve the right balance. This specific molecular weight range provides sufficient chain entanglement and viscosity to resist penetration into voids while maintaining adequate tack and adhesive strength, thus resolving the contradiction between softness and penetration resistance.
Solution Approach 2:
The patent introduces spatial variation in adhesive properties by incorporating UV curable components. The adhesive exhibits soft, penetrative characteristics during initial application for strong bonding, then undergoes localized curing to become hard and penetration-resistant in the cured state, thus achieving both high adhesive force and penetration resistance at different stages.
3Illumination intensity
If the void fraction of the void-containing layer is increased to maintain optical characteristics, then optical performance is improved, but adhesive penetration into voids is facilitated
Solution Approach 1:
The patent changes the molecular weight parameter of the adhesive to a higher range (100,000 to 500,000) to increase viscosity and resistance to penetration. This parameter modification allows the adhesive to maintain sufficient bonding strength while developing enough resistance to prevent penetration into the high void fraction structure, thus enabling both optical performance and penetration resistance.
Solution Approach 2:
The patent formulates a composite adhesive system incorporating UV curable monomers and phot initiators that enable the adhesive to resist penetration into high void fraction structures. The composite formulation provides controlled rheology to prevent excessive penetration while maintaining bonding capability, allowing high void fraction (50-90%) to be achieved for optimal optical performance.
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 configuration achieves both strong adhesive force and reduced adhesive penetration into voids, maintaining optical performance and durability through a heat/humidification test, ensuring a high void remaining ratio and optical clarity.
Implementation Method 1
a pressure-sensitive adhesive/adhesive layer, wherein the pressure-sensitive adhesive/adhesive layer is directly laminated on one or both sides of the void-containing layer
Implementation Method 2
an air layer having a low refractive index is used as a total reflection layer... a low refractive index layer instead of an air layer... void-containing layer having a lower refractive index than that of the light guide plate
Implementation Method 3
the pressure-sensitive adhesive or adhesive constituting the pressure-sensitive adhesive/adhesive layer may penetrate into the voids of the void-containing layer... after a heat/humidification durability test... a void remaining ratio of the void-containing layer is 50 vol % or more
Data Source
AI summary
The present invention provides a laminate of a void-containing layer and a pressure-sensitive adhesive/adhesive layer that achieves both a pressure-sensitive adhesive force or an adhesive force and a reduction of a tendency of a pressure-sensitive adhesive or an adhesive to penetrate into voids. The first laminate of the present invention includes: a void-containing layer (20); and a pressure-sensitive adhesive/adhesive layer (30), wherein the pressure-sensitive adhesive/adhesive layer (30) is directly laminated on one or both sides of the void-containing layer (20), the void-containing layer (20) has a void fraction of 35 vol % or more, and, after a heat/humidification durability test of holding at a temperature of 85° C. and a relative humidity of 85% for 500 hours, a void remaining ratio of the void-containing layer (20) is 50 vol % or more before the heat/humidification durability test.