(Meth)acrylate Adhesive with Siloxane Copolymer for Flexible Optical Films
Solution Overview
Problem
Existing adhesive compositions for optical films face challenges in providing both strong initial adhesion and rework ability, especially under varying environmental conditions, and must also accommodate the mechanical stresses of flexible display devices without creeping or peeling.
Innovation Solution
A (meth)acrylate adhesive composition comprising a (meth)acrylate polymer, a crosslinking agent, and a siloxane copolymer with specific molecular weight and monomer ratios, which includes 70-95% acrylic monomers and 5-30% silane compounds, enhancing adhesion and weather resistance while maintaining flexibility and preventing adhesion increase over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silane-based compounds are added to adhesive compositions to enhance adhesion, then adhesion strength is improved, but adhesion increases excessively at high temperature and humidity causing remaining adhesive on substrate during tearing off
Solution Approach 1:
The patent changes the chemical parameters of the adhesive composition by using specific silane compounds with controlled reaction rates and molecular structures. The silane content is precisely controlled at 1-10 parts by weight per 100 parts by weight of adhesive resin, and the silane undergoes controlled hydrolysis and condensation reactions to form crosslinked structures that provide strong adhesion without excessive adhesion increase under high temperature and humidity conditions.
Solution Approach 2:
The patent creates a composite adhesive system combining adhesive resin, silane compounds, and silane crosslinking agents. This composite formulation synergistically combines the bonding capability of the adhesive resin with the adhesion-enhancing and moisture-curing properties of silane compounds, achieving both strong initial adhesion and controlled adhesion under environmental stress while maintaining reworkability.
2Ease of operation
If cyanoacetyl-containing silane-based compounds are added to adhesive compositions to maintain rework ability, then rework ability is improved, but initial adhesion strength and weather resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific silane compounds (such as alkoxysilanes, halosilanes, or azidosilanes) that do not contain cyanoacetyl groups. These silane compounds are combined with appropriate crosslinking agents to achieve strong initial adhesion through enhanced silane-crosslinked network formation, while the controlled crosslinking density maintains reworkability. The silane content is optimized at 1-10 parts by weight per 100 parts by weight of adhesive resin.
Solution Approach 2:
The patent formulates a composite adhesive system that integrates adhesive resin with selected silane compounds and crosslinking agents. This composite provides both strong initial adhesion through effective silane-crosslinked network formation and good weather resistance through the hydrophobic and chemically stable silane structures, while maintaining reworkability through controlled crosslinking density and composition.
3Strength
If acrylate adhesive is used to provide sufficient adhesion, then adhesion is improved, but adhesion increases over time reducing rework ability
Solution Approach 1:
The patent changes the temporal evolution of adhesion by incorporating silane compounds that undergo controlled hydrolysis and condensation reactions. The silane content is precisely controlled at 1-10 parts by weight per 100 parts by weight of adhesive resin, creating a crosslinked network that develops adhesion gradually without excessive adhesion increase over time, thereby maintaining reworkability while providing sufficient bonding strength.
Solution Approach 2:
The patent introduces dynamic chemical reactions (silane hydrolysis and condensation) that occur over time to form crosslinked structures. This dynamic process allows the adhesive to transition from a initially workable state to a progressively strengthening state, maintaining reworkability during the bonding process while achieving sufficient adhesion strength over time without excessive adhesion increase that would prevent rework.
4Strength
If adhesive has sufficient mechanical properties for optical films, then structural integrity is improved, but flexibility and stress release ability deteriorate
Solution Approach 1:
The patent changes the mechanical parameters of the adhesive by controlling the crosslinking density and network structure through silane compound addition. The silane content is optimized at 1-10 parts by weight per 100 parts by weight of adhesive resin, creating a crosslinked network that provides sufficient mechanical strength while the flexible siloxane bonds and controlled crosslinking density maintain flexibility and stress release ability.
Solution Approach 2:
The patent creates a composite adhesive system combining adhesive resin with silane compounds and crosslinking agents. This composite provides sufficient mechanical properties through the crosslinked network structure while maintaining flexibility and stress release ability through the inherent flexibility of siloxane bonds and controlled crosslinking density, enabling the adhesive to accommodate mechanical modulus differences between optical films during bending.
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 adhesive composition achieves stable initial adhesion strength, excellent weather resistance, and rework ability, along with flexibility and stress release properties suitable for flexible display devices, maintaining performance under high temperature and humidity.
Implementation Method 1
silane compounds with the function of enhancing the adhesion to the substrate
Implementation Method 2
a crosslinking agent
Implementation Method 3
the adhesive between each film layer needs to have the release and absorbing ability of the bending stress
Implementation Method 4
the siloxane copolymer comprises the acrylic monomers of polarity compatible with the (meth)acrylate polymer
Data Source
AI summary
The present disclosure relates to a (meth)acrylate adhesive composition comprising a (meth)acrylated polymer, a crosslinking agent and a silane copolymer, wherein the silane copolymer comprises 70 to 95 weight parts of an acrylate monomer containing C1-C4 alkyl group and 5 to 30 weight parts of a silane represented by the following formula (I):X—R1—SiR23-a(OR3)a (I)wherein the weight-average molecular weight of the silane copolymer is ranging from 40,000 to 150,000. The silane copolymer can enhance the initial adhesion strength, rework ability and weather resistance of the (meth)acrylate adhesive composition. Furthermore, the (meth)acrylate adhesive composition can be used in the flexible optical film with a good bending restoring property and adhesion.