Oca optical adhesive compositions, methods of making, methods of curing, and applications

Abstract

The application belongs to the technical field of optical adhesive, and particularly relates to an OCA optical adhesive composition, a preparation method, a curing method and application. The raw materials of the OCA optical adhesive composition include the following components in parts by weight: 65-85 parts of an acrylate soft monomer, 8-18 parts of an acrylate hard monomer, 1-5 parts of a fluorine-containing acrylate monomer, 4-12 parts of a functional monomer containing a polar group, 0.5-3 parts of a photoinitiator, 0.5-2 parts of a multifunctional crosslinking agent, 0.1-0.5 parts of a silane coupling agent and 0.2-1.5 parts of a functional additive.

Description

Technical Field

[0001] This invention belongs to the field of optical adhesive technology, and particularly relates to OCA optical adhesive compositions, preparation methods, curing methods and applications. Background Technology

[0002] Optical pressure-sensitive adhesive (OCA) is a key bonding material in the optoelectronic display and touch control fields, widely used in various display systems and other terminal devices. With the development of smart cockpit and large-size panoramic sunroof technologies, the application of polymer-dispersed liquid crystal (PDLC) dimming films in automotive sunroofs is becoming increasingly popular. PDLC dimming films require large-area curved surface bonding between two layers of glass or polyester film. This application scenario requires OCA optical adhesive to have visible light transmittance and low haze characteristics that meet standard specifications, and to meet test indicators such as high temperature resistance, high humidity resistance, and UV aging resistance in automotive environments. The working mechanism of PDLC film relies on an external electric field to drive the orientation distribution of liquid crystal molecules, and the dielectric constant of the adhesive layer is directly related to the electric field transmission efficiency during the dimming response process.

[0003] Conventional OCA optical adhesives, when applied to PDLC dimming films, are prone to generating electric field losses, increasing system energy consumption and reducing dimming response rates. To reduce the dielectric constant or adjust the optical refractive index, existing technologies employ chemical modification methods such as introducing non-polar solvents or adding a large proportion of fluoropolymers. Chinese invention patent CN109810638B discloses a low-refractive-index optical pressure-sensitive adhesive. Its formulation contains 70 to 85 parts by weight of a fluorinated acrylate polymer. Such a high proportion of fluorinated polymers significantly reduces the surface energy of the system, causing a decrease in the peel strength of the adhesive layer to glass and PET substrates. Chinese invention patent CN112175526A prepares a low-dielectric OCA optical adhesive by adding 30 to 40 parts by weight of a non-polar solvent to the raw materials. In the coating and bonding process of large-size, thick adhesive layers (usually over 50μm) for vehicle sunroofs, the residual volatile solvents in the system are at risk of vaporization and overflow under high temperature exposure and constant temperature aging environment, which can easily form bubbles and delamination at the substrate interface.

[0004] The bonding process for large-area curved PDLC canopies is affected by electrostatic effects. The large-area PDLC film and its conductive coating easily attract fine dust from the production environment during fabrication, causing visual defects within the optical windows. Conventional thick-layer optical adhesives often face the challenge of inconsistent cross-linking densities between the surface and underlying layers during deep curing, leading to cohesive failure and high-temperature peeling of adhesive residue. For the practical application of large-area curved PDLC canopies, the key technical challenge is to develop a thick-layer optical adhesive that, while avoiding solvent evaporation-induced bubble defects, reduces electric field penetration loss under high-frequency dimming conditions, and simultaneously overcomes the problems of electrostatic dust attraction and differences in deep curing of thick adhesive layers during large-area application. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and to provide an OCA optical adhesive composition, preparation method, curing method, and application.

[0006] In a first aspect, an OCA optical adhesive composition employs the following technical solution: An OCA optical adhesive composition, wherein the raw materials of the OCA optical adhesive composition, by weight, include the following components: 65-85 parts of acrylate soft monomers, 8-18 parts of acrylate hard monomers, 1-5 parts of fluorinated acrylate monomers, 4-12 parts of functional monomers containing polar groups, 0.5-3 parts of photoinitiator, 0.5-2 parts of multifunctional crosslinking agent, 0.1-0.5 parts of silane coupling agent, and 0.2-1.5 parts of functional additives.

[0007] Furthermore, the acrylate soft monomer is selected from one or more of 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate, and n-octyl acrylate; The acrylate hard monomers are selected from one or more of methyl methacrylate, isobornyl acrylate, and cyclohexyl acrylate. The polar functional monomer is selected from one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate. The fluorinated acrylate monomers are selected from one or more of trifluoroethyl acrylate, pentafluorooctyl acrylate, hexafluorobutyl acrylate, and octafluoropentyl acrylate; The multifunctional crosslinking agent is selected from one or more of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate.

[0008] Furthermore, the acrylate soft monomers include 55 to 65 parts of 2-ethylhexyl acrylate and 10 to 20 parts of butyl acrylate.

[0009] Furthermore, the photoinitiator includes a primary photoinitiator and an auxiliary photoinitiator; the primary photoinitiator is selected from one or two of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; the auxiliary photoinitiator is selected from one or two of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0010] Furthermore, the functional additives include antioxidants, antistatic agents, and leveling agents; the antioxidant is a hindered phenolic antioxidant; the antistatic agent is a polymeric antistatic agent; and the leveling agent is an acrylate leveling agent.

[0011] Furthermore, the hindered phenolic antioxidant is selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; The polymeric antistatic agent is selected from one or more of the following: polyether-type polyurethane block copolymers, ionic liquid modified polymers containing bis(trifluoromethanesulfonyl)imide anions, quaternary ammonium salt-type (meth)acrylate copolymers, and polyoxyethylene ether polymer derivatives. The acrylate leveling agent is selected from one or more of the following: polybutyl acrylate homopolymer, fluorinated polyacrylate copolymer, and block copolymer of alkyl acrylate and (meth)acrylic acid.

[0012] Secondly, a method for preparing an OCA optical adhesive composition adopts the following technical solution: A method for preparing an OCA optical adhesive composition includes the following steps: Step (1): At room temperature, the acrylate soft monomer, acrylate hard monomer, fluorinated acrylate monomer and polar functional monomer are mixed and stirred for a first preset time to fully disperse them and obtain monomer mixture. Step (2): Add the photoinitiator, multifunctional crosslinking agent, silane coupling agent and functional additive to the monomer mixture obtained in step (1) in sequence, continue stirring for a second preset time, seal in the dark, and the OCA optical adhesive composition is obtained.

[0013] Furthermore, the first preset time is 20 min to 40 min, and the second preset time is 30 min to 50 min.

[0014] Thirdly, a curing method for an OCA optical adhesive composition employs the following technical solution: A method for curing an OCA optical adhesive composition includes the following steps: UV curing under a nitrogen atmosphere, wherein the UV light irradiation energy is 800 mJ / cm². 2 ~1200mJ / cm 2 The irradiation wavelength is 365nm.

[0015] Fourthly, the application of an OCA optical adhesive composition employs the following technical solution: Application of an OCA optical adhesive composition in PDLC smart canopy.

[0016] The beneficial effects of this invention are: This invention provides an OCA optical adhesive composition. Through copolymerization of specific weight parts of acrylate soft monomers and hard monomers, a basic viscoelastic network with both deformation adaptability and cohesive strength is constructed, ensuring stress dispersion at curved bonding interfaces and suppressing peeling residue under high-temperature conditions. This OCA optical adhesive composition employs a solvent-free system and is formulated with primary and secondary photoinitiators. While eliminating the risk of residual solvent vaporization and escape from thick adhesive layers upon heating, it achieves uniform crosslinking density between the surface and deep layers through the synergistic generation of free radicals initiated by long and short wavelength light. Furthermore, fluorinated acrylate monomers within the system are covalently embedded in the polymer backbone. Utilizing the high electronegativity and low polarizability of fluorine atoms, the dielectric constant of the adhesive layer is reduced at the molecular chain structure level without causing a drastic decrease in surface energy and maintaining adhesion to the substrate. This reduces energy loss of the PDLC film under high-frequency alternating electric fields, maintaining light transmittance. In addition, the combined use of polymeric antistatic agents, multifunctional crosslinking agents, and coupling agents facilitates the removal of accumulated charges on the surface of the large-area conductive layer during the bonding stage, eliminates optical interference caused by adsorbed free dust, and solidifies the anti-aging physical barrier of the three-dimensional crosslinked network, maintaining the light transmittance and dimensional stability of the composition in complex outdoor environments. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, this application will be described in further detail below. The described embodiments should not be regarded as limitations on this invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] In the following description, references to "some embodiments" refer to a subset of all possible embodiments; however, it is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict. Unless otherwise defined, all technical and scientific terms used in the embodiments of the invention have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of the invention pertain. The terminology used in the embodiments of the invention is for the purpose of describing the embodiments of the invention only and is not intended to limit the invention.

[0019] Those skilled in the art should understand that, in the following description of the embodiments of the present invention, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0020] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0021] Those skilled in the art will understand that the numerical ranges in the embodiments of the present invention should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value and an intermediate value within the stated range, as well as any other stated value or an intermediate value within the stated range, is also included within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in embodiments or test cases of the invention. All references to this specification are generally incorporated herein by reference to disclose and describe methods and / or materials associated with said references. In the event of any conflict with any incorporated reference, the contents of this application shall prevail.

[0023] It should be noted that all raw materials and / or reagents in the embodiments of the present invention were purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0024] Example Example 1 This embodiment 1 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 60 g of 2-ethylhexyl acrylate, 15 g of butyl acrylate; Acrylate hard monomers: methyl methacrylate 12 g; Fluorinated acrylate monomers: 3 g of trifluoroethyl acrylate; Functional monomers containing polar groups: 3 g of acrylic acid, 5 g of hydroxyethyl acrylate; Photoinitiator: 1 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.5 g of 1-hydroxycyclohexylphenyl ketone; Multifunctional crosslinking agent: 1 g of trimethylolpropane triacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.2 g; Functional additives: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] 0.3 g, polyether-type polyurethane block copolymer 0.2 g, polybutyl acrylate homopolymer 0.1 g.

[0025] This embodiment 1 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate, trifluoroethyl acrylate, acrylic acid and hydroxyethyl acrylate to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 30 minutes to fully disperse the monomer components and obtain a uniform monomer mixture.

[0026] Step (2): Add diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, trimethylolpropane triacrylate, γ-methacryloyloxypropyltrimethoxysilane, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], polyether-type polyurethane block copolymer and polybutyl acrylate homopolymer to the monomer mixture obtained in step (1) in sequence; continue stirring for 40 min to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture; after mixing, transfer the obtained colloidal liquid to a light-proof container and seal it to obtain the solvent-free OCA optical adhesive composition.

[0027] Example 2 This embodiment 2 provides an OCA optical adhesive composition, the raw materials of which include the following components: acrylate soft monomers: 55 g of isooctyl acrylate, 10 g of n-octyl acrylate; Acrylate hard monomers: Isoborneol acrylate 8 g; Fluorinated acrylate monomers: 1 g of pentafluorooctyl acrylate; Functional monomers containing polar groups: 4 g of methacrylic acid; Photoinitiator: 0.3 g of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 0.2 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone; Multifunctional crosslinking agent: 0.5 g of 1,6-hexanediol diacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.1 g; Functional additives: 0.1 g of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, 0.05 g of ionic liquid modified polymer containing bis(trifluoromethanesulfonyl)imide anion, and 0.05 g of fluorinated polyacrylate copolymer.

[0028] This embodiment 2 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add isooctyl acrylate, n-octyl acrylate, isobornyl acrylate, pentafluorooctyl acrylate and methacrylic acid to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 20 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0029] Step (2): 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1,6-hexanediol diacrylate, γ-methacryloyloxypropyltrimethoxysilane, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol, ionic liquid modified polymer containing bis(trifluoromethanesulfonyl)imide anion, and fluorine-modified polyacrylate copolymer are added sequentially to the monomer mixture obtained in step (1). Stirring is continued for 30 min to ensure that the main and auxiliary initiators, crosslinking agents, and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture. After mixing, the resulting colloidal liquid is transferred to a light-proof container and sealed to obtain a solvent-free OCA optical adhesive composition.

[0030] Example 3 This embodiment 3 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 65 g of 2-ethylhexyl acrylate, 20 g of butyl acrylate; Acrylate hard monomers: cyclohexyl acrylate 18 g; Fluorinated acrylate monomers: hexafluorobutyl acrylate 5 g; Functional monomers containing polar groups: 12 g of hydroxypropyl acrylate; Photoinitiator: 2 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1 g of 1-hydroxycyclohexylphenyl ketone; Multifunctional crosslinking agent: 2 g of tripropylene glycol diacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.5 g; Functional additives: 0.5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of quaternary ammonium salt type (meth)acrylate copolymer, and 0.5 g of block copolymer of alkyl acrylate and (meth)acrylic acid.

[0031] This embodiment 3 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, butyl acrylate, cyclohexyl acrylate, hexafluorobutyl acrylate and hydroxypropyl acrylate to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 40 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0032] Step (2): Add diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, tripropylene glycol diacrylate, γ-methacryloyloxypropyltrimethoxysilane, 2,6-di-tert-butyl-4-methylphenol, quaternary ammonium salt type (meth)acrylate copolymer and alkyl acrylate and (meth)acrylic acid block copolymer to the monomer mixture obtained in step (1) in sequence; continue stirring for 50 min to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture; after mixing, transfer the obtained colloidal liquid to a light-proof container and seal it to obtain the solvent-free OCA optical adhesive composition.

[0033] Example 4 Example 4 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 58 g of 2-ethylhexyl acrylate, 12 g of isooctyl acrylate; Acrylate hard monomers: methyl methacrylate 10 g, isobornyl acrylate 5 g; Fluorinated acrylate monomers: octafluoroamyl acrylate 2 g; Functional monomers containing polar groups: 5 g acrylic acid, 3 g hydroxybutyl acrylate; Photoinitiator: 1 g of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 0.8 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone; Multifunctional crosslinking agent: 1.2 g of trimethylolpropane triacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.3 g; Functional additives: 0.3 g of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.3 g of polyoxyethylene ether polymer derivatives, and 0.2 g of polybutyl acrylate homopolymer.

[0034] Example 4 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, isooctyl acrylate, methyl methacrylate, isobornyl acrylate, octafluoropentyl acrylate, acrylic acid and hydroxybutyl acrylate into the mixing container; turn on the stirring equipment and maintain constant speed stirring for 25 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0035] Step (2): 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, trimethylolpropane triacrylate, γ-methacryloyloxypropyltrimethoxysilane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, polyoxyethylene ether polymer derivatives and polybutyl acrylate homopolymer are added sequentially to the monomer mixture obtained in step (1). Stirring is continued for 35 min to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture. After mixing, the resulting colloidal liquid is transferred to a light-proof container and sealed to obtain a solvent-free OCA optical adhesive composition.

[0036] Example 5 This embodiment 5 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 75 g of 2-ethylhexyl acrylate; Acrylic hard monomers: methyl methacrylate 10 g; Fluorinated acrylate monomers: 4 g of trifluoroethyl acrylate; Functional monomers containing polar groups: 6 g of hydroxyethyl acrylate; Photoinitiator: 1.2 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.3 g of 1-hydroxycyclohexylphenyl ketone; Multifunctional crosslinking agent: 0.8 g of 1,6-hexanediol diacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.2 g; Functional additives: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] 0.4 g, polyether-type polyurethane block copolymer 0.4 g, fluorinated polyacrylate copolymer 0.2 g.

[0037] This embodiment 5 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, methyl methacrylate, trifluoroethyl acrylate and hydroxyethyl acrylate to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 35 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0038] Step (2): Add diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, 1,6-hexanediol diacrylate, γ-methacryloyloxypropyltrimethoxysilane, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], polyether-type polyurethane block copolymer, and fluorinated polyacrylate copolymer to the monomer mixture obtained in step (1) in sequence; continue stirring for 45 min to ensure that the main and auxiliary initiators, crosslinking agents, and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture; after mixing, transfer the resulting colloidal liquid to a light-proof container and seal it to obtain the solvent-free OCA optical adhesive composition.

[0039] Example 6 Example 6 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 50 g of 2-ethylhexyl acrylate, 30 g of butyl acrylate; Acrylate hard monomers: cyclohexyl acrylate 12 g; Fluorinated acrylate monomers: 2 g of hexafluorobutyl acrylate and 2 g of pentafluorooctyl acrylate; Functional monomers containing polar groups: 3 g of methacrylic acid, 4 g of hydroxyethyl acrylate; Photoinitiator: 1.5 g of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 0.5 g of 1-hydroxycyclohexylphenyl ketone; Multifunctional crosslinking agent: 1.5 g of tripropylene glycol diacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.4 g; Functional additives: 0.5 g of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, 0.3 g of ionic liquid modified polymer containing bis(trifluoromethanesulfonyl)imide anion, and 0.2 g of block copolymer of alkyl acrylate and (meth)acrylic acid.

[0040] This embodiment 6 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, butyl acrylate, cyclohexyl acrylate, hexafluorobutyl acrylate, pentafluorooctyl acrylate, methacrylic acid and hydroxyethyl acrylate to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 30 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0041] Step (2): 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, tripropylene glycol diacrylate, γ-methacryloyloxypropyltrimethoxysilane, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol, ionic liquid modified polymer containing bis(trifluoromethanesulfonyl)imide anion, and block copolymer of alkyl acrylate and (meth)acrylic acid are added sequentially to the monomer mixture obtained in step (1). Stirring is continued for 40 minutes to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture. After mixing, the resulting colloidal liquid is transferred to a light-proof container and sealed to obtain the solvent-free OCA optical adhesive composition.

[0042] Example 7 This embodiment 7 provides an OCA optical adhesive composition, the raw materials of which include the following components: Soft monomers of acrylates: 55 g of 2-ethylhexyl acrylate, 20 g of butyl acrylate; Acrylate hard monomers: Isoborneol acrylate 16 g; Fluorinated acrylate monomer: octafluoroamyl acrylate 1.5 g; Functional monomers containing polar groups: 10 g of hydroxypropyl acrylate; Photoinitiator: 0.8 g of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 0.2 g of 2-hydroxy-2-methyl-1-phenyl-1-propanone; Multifunctional crosslinking agent: 0.5 g of trimethylolpropane triacrylate and 0.5 g of 1,6-hexanediol diacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.25 g; Functional additives: 0.2 g of 2,6-di-tert-butyl-4-methylphenol, 0.2 g of quaternary ammonium salt (meth)acrylate copolymer, and 0.2 g of polybutyl acrylate homopolymer.

[0043] This embodiment 7 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add 2-ethylhexyl acrylate, butyl acrylate, isobornyl acrylate, octafluoropentyl acrylate and hydroxypropyl acrylate to the mixing container; turn on the stirring equipment and maintain constant speed stirring for 28 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0044] Step (2): Add diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, γ-methacryloyloxypropyltrimethoxysilane, 2,6-di-tert-butyl-4-methylphenol, quaternary ammonium salt (meth)acrylate copolymer and polybutyl acrylate homopolymer to the monomer mixture obtained in step (1) in sequence; continue stirring for 38 min to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture; after mixing, transfer the obtained colloidal liquid to a light-proof container and seal it to obtain the solvent-free OCA optical adhesive composition.

[0045] Example 8 This embodiment 8 provides an OCA optical adhesive composition, the raw materials of which include the following components: Acrylic ester soft monomers: 40 g of n-octyl acrylate, 30 g of butyl acrylate; Acrylic hard monomers: methyl methacrylate 7 g, cyclohexyl acrylate 7 g; Fluorinated acrylate monomers: 2 g of trifluoroethyl acrylate and 1 g of hexafluorobutyl acrylate; Functional monomers containing polar groups: 5 g of acrylic acid, 4 g of hydroxybutyl acrylate; Photoinitiator: 1 g of 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 0.5 g of 1-hydroxycyclohexylphenyl ketone; Multifunctional crosslinking agent: 1.8 g of trimethylolpropane triacrylate; Silane coupling agent: γ-methacryloyloxypropyltrimethoxysilane 0.35 g; Functional additives: 0.4 g of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 0.4 g of polyoxyethylene ether polymer derivatives, and 0.3 g of fluorinated modified polyacrylate copolymer.

[0046] This embodiment 8 also provides a method for preparing an OCA optical adhesive composition, comprising the following steps: Step (1): At room temperature, add n-octyl acrylate, butyl acrylate, methyl methacrylate, cyclohexyl acrylate, trifluoroethyl acrylate, hexafluorobutyl acrylate, acrylic acid and hydroxybutyl acrylate into the mixing container; turn on the stirring equipment and maintain constant speed stirring for 32 min to fully disperse the monomer components and obtain a uniform monomer mixture.

[0047] Step (2): 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, trimethylolpropane triacrylate, γ-methacryloyloxypropyltrimethoxysilane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, polyoxyethylene ether polymer derivatives and fluorinated polyacrylate copolymers are added sequentially to the monomer mixture obtained in step (1). Stirring is continued for 42 min to ensure that the main and auxiliary initiators, crosslinking agents and various trace functional additives are completely dissolved and evenly dispersed in the monomer mixture. After mixing, the resulting colloidal liquid is transferred to a light-proof container and sealed to obtain the solvent-free OCA optical adhesive composition.

[0048] Comparative Example Comparative Example 1 Comparative Example 1 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, the only difference being that the raw material components do not contain fluorinated acrylate monomers. Specifically, trifluoroethyl acrylate is not added, and its 3 g mass is replaced with an equal mass of the main soft monomer, that is, the amount of 2-ethylhexyl acrylate is increased from 60 g to 63 g.

[0049] Comparative Example 2 Comparative Example 2 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, the only difference being that the proportion of fluorinated acrylate monomers is greatly increased. Specifically, referring to the prior art document CN109810638B, the amount of trifluoroethyl acrylate is increased to 75 g, while the amount of 2-ethylhexyl acrylate is reduced to 15 g, and butyl acrylate is removed.

[0050] Comparative Example 3 Comparative Example 3 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, the only difference being that: a compound photoinitiator system is not used, specifically: the main photoinitiator diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide is not added to the formulation, only the auxiliary photoinitiator 1-hydroxycyclohexylphenyl ketone is used, and its amount is adjusted to 1.5 g.

[0051] Comparative Example 4 Comparative Example 4 provides an OCA optical adhesive composition that differs from Example 1 in that a volatile non-polar solvent is added to the raw material composition. Specifically, based on the raw materials of Example 1, 35 g of ethyl acetate is added (refer to the amount of non-polar solvent in comparative document CN112175526A).

[0052] Accordingly, the preparation method involves the addition of solvents, and the specific steps are adjusted as follows: Step (1): At room temperature, ethyl acetate, 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate, trifluoroethyl acrylate, acrylic acid and hydroxyethyl acrylate are added to the mixing container. The stirring device is turned on and the stirring is maintained at a constant speed for 30 min to allow the solvent and monomer components to be fully miscible and dispersed to obtain a uniform solvent-containing monomer mixture.

[0053] The operation of step (2) is completely consistent with that of Example 1.

[0054] Comparative Example 5 Comparative Example 5 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, the only difference being that the raw material components do not contain a polymeric antistatic agent. Specifically, polyether-type polyurethane block copolymers are not added to the functional additives.

[0055] Comparative Example 6 Comparative Example 6 provides an OCA optical adhesive composition, which is prepared in a manner that is basically the same as that in Example 1, except that the amount of methyl methacrylate is increased from 12 g to 30 g, and the amount of 2-ethylhexyl acrylate is reduced accordingly to 42 g.

[0056] Comparative Example 7 Comparative Example 7 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, except that the amount of trimethylolpropane triacrylate is increased from 1 g to 4.5 g.

[0057] Comparative Example 8 Comparative Example 8 provides an OCA optical adhesive composition, the preparation method of which is basically the same as that of Example 1, the only difference being that: no highly polar acrylic monomer is added, and the missing 3 g mass is completely replaced with hydroxyethyl acrylate, that is, the amount of hydroxyethyl acrylate is increased to 8 g.

[0058] Application Examples This application example is used to prepare optical adhesive film samples containing the OCA optical adhesive compositions of Examples 1-8 and Comparative Examples 1-8 above, to provide a standard test carrier for subsequent performance verification. The specific preparation process is as follows: The liquid OCA optical adhesive compositions prepared in Examples 1-8 and Comparative Examples 1-8 were extracted respectively. Using a coating device, each adhesive composition was uniformly coated onto the surface of a 50 μm thick transparent release film. During the coating process, by adjusting the gap parameters and traction speed of the coating die, each adhesive formulation was controlled to independently form three liquid adhesive layers of different thicknesses, set to 52 μm, 72 μm, and 92 μm respectively.

[0059] After the liquid adhesive layer is coated on the surface, in a dust-free operating environment, another transparent release film with the same thickness of 50 μm is laminated onto the open surface of each liquid adhesive layer to eliminate the trapped air between the layers, thereby constructing a sandwich structure of "50 μm transparent release film-OCA liquid adhesive layer-50 μm transparent release film".

[0060] The composite sandwich structure was placed in a sealed curing chamber filled with high-purity nitrogen to completely purge oxygen and block the oxygen inhibition effect during free radical polymerization. All test samples were then treated with the exact same curing method: the UV curing light source was activated, the irradiation wavelength was set to 365 nm, and the UV light irradiation energy was strictly controlled to 1000 mJ / cm². 2 Continuous irradiation is performed. Under ultraviolet light excitation at specific wavelengths and energies, the photoinitiator inside the adhesive liquid decomposes to generate free radicals, driving a deep three-dimensional cross-linking reaction between the soft and hard monomers, functional monomers, and cross-linking agents, thus solidifying the liquid adhesive layer into a high-molecular viscoelastic matrix. After the irradiation process is completed, a series of OCA optical film samples with three thicknesses of 52 μm, 72 μm, and 92 μm are obtained, corresponding to the formulations of each embodiment and comparative example.

[0061] Performance testing To objectively verify the actual effect of the OCA optical adhesive composition provided by this invention, corresponding test samples were prepared and subjected to various physical and optical performance tests. The test indicators covered transmittance, haze, dielectric constant, peel strength, and durability assessment under simulated extreme environments. The specific test steps are as follows: Optical performance testing: The release film on one side of each prepared OCA film of various thicknesses was removed, and the film was flatly attached to a 1mm thick standard optical glass slide. The release film on the other side was then removed. The visible light transmittance and optical haze of the samples were measured using a high-precision haze meter at room temperature.

[0062] Dielectric constant test: The release film on both sides of the sample was peeled off and clamped between the test plates. The dielectric constant of the sample was determined using an LCR digital bridge tester at an AC test frequency of 1MHz. In the actual operation of PDLC dimming films, the applied electric field needs to penetrate the adhesive layer to drive the liquid crystal molecules. The value of this index directly determines the effective electric field transmittance and energy loss.

[0063] Peel strength test: According to GB / T 2792 standard, the sample was cut into strips 25mm wide, the release layer was removed, and the strips were attached to a flat float glass surface cleaned with isopropyl alcohol. A 2kg standard roller was used to roll the sample back and forth three times to remove micro-bubbles at the interface. After standing for 20 minutes, the sample was fixed on the fixture of a tensile testing machine, and a 180° peel test was performed at a constant tensile speed of 300mm / min. The average peel force data was recorded.

[0064] Durability and Reliability Testing: This test includes extreme verification of resistance to damp heat and high temperature. Samples with completed glass bonding are immersed in a constant temperature water bath at 49℃~54℃ for 336 hours for damp heat resistance testing; simultaneously, another set of samples is placed in a constant temperature aging chamber at 90℃ for 2000 hours for high temperature aging resistance testing. After the test cycle, the appearance of the adhesive film is macroscopically observed under natural light, and the presence of interface failure defects such as bubbles, whitening, curling, or delamination is recorded.

[0065] Antistatic and dustproof testing: Simulating the industrial workshop environment of actual canopy coating and lamination operations, the single-sided peeled adhesive layer was exposed and left to stand in a specific micro-dust environment chamber for 5 minutes. Substrate lamination was then completed, and the interface contaminant adsorption was observed using a microscope. The degree of haze degradation before and after the exposure was recorded.

[0066] Performance test results data table Table 1 below records the performance data of Examples 1-8 and Comparative Examples 1-8 at three different coating thicknesses of 52μm, 72μm, and 92μm.

[0067] Table 1 Performance test results of the optical specimens provided in Examples 1-8 and Comparative Examples 1-8

[0068] Test data from Examples 1-8 at three coating thickness gradients of 52μm, 72μm, and 92μm show that the dielectric constant of the example group remains in the low range of 2.8-3.2 even with the variable intervention of doubling the coating thickness. This effectively controls the reactive power loss when the alternating electric field passes through the thick canopy colloid at the material level, ensuring effective electric field penetration and dimming response rate. With increasing optical path length, the visible light transmittance of the example group at a thickness of 92μm remains above 93.6%, and the optical haze is below 0.94%, meeting the high-fidelity clarity optical requirements of the intelligent panoramic window. Under constant temperature aging and extreme boiling water damage environments, the viscoelastic network of the specific soft and hard monomer architecture exhibits better stress dissipation capability with increasing thickness. The interfacial peel strength of each embodiment shows a benign positive correlation with thickness and is stable in the optimal working range of 8~12N / 25mm. No interfacial failure characteristics such as bubble precipitation or hydrolytic peeling were observed, which verifies the reliability of the optical adhesive composition system provided by the present invention in dealing with large-size thick adhesive bonding scenarios in automotive applications.

[0069] The test data of Comparative Examples 1-8 were compared with those of Reference Example 1 under the same thickness conditions. Comparative Example 1, lacking a fluorinated monomer, exhibited a dielectric constant jump to 4.2, hindering the penetration efficiency of the driving electric field of the terminal canopy. Comparative Example 2, employing a large amount of fluorinated polymer to reduce the refractive index, experienced accelerated attenuation of surface tension with increasing thickness, resulting in a peel force of only 2.4 N / 25 mm at a thickness of 92 μm, leading to spontaneous detachment. Comparative Example 3, using a single photoinitiator, showed that as the thickness increased from 52 μm to 92 μm, the deep curing dead zone caused haze to climb to 1.85%, resulting in severe cohesive residue. Comparative Example 4, with its non-polar volatile solvent trapped deep within the UV crosslinking network, exhibited increased vaporization and expansion due to high-temperature baking as the coating thickened. The larger the solvent volume, the more likely it is to destroy the network structure in the 92μm sample, leading to large-area whitening and delamination. In Comparative Example 5, after the antistatic component was removed, the bare insulating adhesive surface became a dust adsorption layer. During exposure, the adsorbed free particles caused the haze of the three sets of thick samples to increase sharply to over 2.4%. In Comparative Example 6, the excess hard monomers and the excessive multifunctional crosslinking points in Comparative Example 7 altered the original flexible deformation modulus of the colloid. The adhesive film became increasingly rigid and brittle with increasing thickness, and stress wrinkling and brittle powdering fracture frequently occurred during curved surface bonding verification. In Comparative Example 8, after the polar hydrogen bonded molecules were removed, the chemical anchoring channel between the organic matrix and the inorganic interface was cut off. Under the dual effects of the shrinkage stress of the thick adhesive layer itself and the erosion of external water flow, the 92μm sample quickly lost its structural adhesion.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An OCA optical adhesive composition, characterized in that, The raw materials of the OCA optical adhesive composition, by weight, include the following components: 65-85 parts of acrylate soft monomers, 8-18 parts of acrylate hard monomers, 1-5 parts of fluorinated acrylate monomers, 4-12 parts of functional monomers containing polar groups, 0.5-3 parts of photoinitiator, 0.5-2 parts of multifunctional crosslinking agent, 0.1-0.5 parts of silane coupling agent, and 0.2-1.5 parts of functional additives.

2. The OCA optical adhesive composition according to claim 1, characterized in that, The acrylate soft monomers are selected from one or more of 2-ethylhexyl acrylate, butyl acrylate, isooctyl acrylate, and n-octyl acrylate. The acrylate hard monomers are selected from one or more of methyl methacrylate, isobornyl acrylate, and cyclohexyl acrylate. The polar functional monomer is selected from one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate. The fluorinated acrylate monomers are selected from one or more of trifluoroethyl acrylate, pentafluorooctyl acrylate, hexafluorobutyl acrylate, and octafluoropentyl acrylate; The multifunctional crosslinking agent is selected from one or more of trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate.

3. The OCA optical adhesive composition according to claim 2, characterized in that, The acrylate soft monomers include 55 to 65 parts of 2-ethylhexyl acrylate and 10 to 20 parts of butyl acrylate.

4. The OCA optical adhesive composition according to claim 1, characterized in that, The photoinitiator includes a primary photoinitiator and an auxiliary photoinitiator; the primary photoinitiator is selected from one or two of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; the auxiliary photoinitiator is selected from one or two of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

5. The OCA optical adhesive composition according to claim 1, characterized in that, The functional additives include antioxidants, antistatic agents, and leveling agents; the antioxidants are hindered phenolic antioxidants; the antistatic agents are polymeric antistatic agents; and the leveling agents are acrylate leveling agents.

6. The OCA optical adhesive composition according to claim 5, characterized in that, The hindered phenolic antioxidant is selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-4-methylphenol, and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; The polymeric antistatic agent is selected from one or more of the following: polyether-type polyurethane block copolymers, ionic liquid modified polymers containing bis(trifluoromethanesulfonyl)imide anions, quaternary ammonium salt-type (meth)acrylate copolymers, and polyoxyethylene ether polymer derivatives. The acrylate leveling agent is selected from one or more of the following: polybutyl acrylate homopolymer, fluorinated polyacrylate copolymer, and block copolymer of alkyl acrylate and (meth)acrylic acid.

7. A method for preparing the OCA optical adhesive composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step (1): At room temperature, the acrylate soft monomer, acrylate hard monomer, fluorinated acrylate monomer and polar functional monomer are mixed and stirred for a first preset time to fully disperse them and obtain monomer mixture. Step (2): Add the photoinitiator, multifunctional crosslinking agent, silane coupling agent and functional additive to the monomer mixture obtained in step (1) in sequence, continue stirring for a second preset time, seal in the dark, and the OCA optical adhesive composition is obtained.

8. The preparation method according to claim 7, characterized in that, The first preset time is 20 min to 40 min, and the second preset time is 30 min to 50 min.

9. A method for curing the OCA optical adhesive composition according to any one of claims 1 to 6, characterized in that, Includes the following steps: UV curing was performed under a nitrogen atmosphere, with a UV light irradiation energy of 800 mJ / cm². 2 ~1200mJ / cm 2 The irradiation wavelength is 365nm.

10. The application of an OCA optical adhesive composition as described in any one of claims 1 to 6 in a PDLC smart canopy.

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