KR-20260064826-A - Photocurable adhesive composition, optically clear adhesive and display device comprising the same

KR20260064826AKR 20260064826 AKR20260064826 AKR 20260064826AKR-20260064826-A

Abstract

The present invention relates to a photocurable adhesive composition, an optical transparent adhesive manufactured using the same, and a display device. By including a structural unit derived from a compound represented by Chemical Formula 1 in a partially polymerized acrylic copolymer, it exhibits excellent step coverage characteristics after dual curing, while simultaneously exhibiting excellent heat resistance, thereby suppressing the occurrence of bubbles or lifting even after a long period of time under high temperature or high temperature/high humidity conditions.

Inventors

탁명호
박정은
김아란
김지윤
남병기

Assignees

주식회사 테이팩스

Dates

Publication Date: 20260508
Application Date: 20241029

Claims (11)

It comprises a partially polymerized acrylic copolymer and a photoinitiator, A photocurable adhesive composition wherein the partially polymerized acrylic copolymer is partially polymerized to include a compound represented by the following chemical formula 1. [Chemical Formula 1]
In claim 1, The above partially polymerized acrylic copolymer is, A low-temperature glass transition (meth)acrylate monomer having a glass transition temperature of 50°C or lower of the homopolymer; A high-temperature glass transition (meth)acrylate monomer having a glass transition temperature of greater than 50°C of the homopolymer; and A photocurable adhesive composition partially polymerized to further include a (meth)acrylate monomer having a hydrophilic group.
In claim 1, The above photocurable adhesive composition is a photocurable adhesive composition that does not contain a crosslinking agent.
An optically transparent adhesive comprising a cured product of the photocurable adhesive composition of claim 1.
In claim 4, The above-mentioned cured product is an optically transparent adhesive obtained by dual-curing a photocurable adhesive composition.
In claim 5, The above-mentioned optical transparent adhesive is an optical transparent adhesive having a step coverage of 40㎛ or more at a thickness of 250㎛ after dual curing.
In claim 5, The above-mentioned optical transparent adhesive is an optical transparent adhesive that does not produce bubbles after 240 hours at a temperature of 120°C following dual curing.
In claim 5, The above-mentioned optical transparent adhesive is an optical transparent adhesive that does not produce bubbles after 240 hours under conditions of a temperature of 85°C and a humidity of 85% following dual curing.
In claim 5, The above dual curing includes primary curing and secondary curing, and The above first curing is to irradiate light with a wavelength of 315 to 400 nm at an intensity of 1 to 40 mW, and An optical transparent adhesive, wherein the above secondary curing is performed by irradiating light with a wavelength of 265 to 420 nm at an intensity of 50 to 150 mW.
A display device comprising the optically transparent adhesive of claim 4.
In claim 10, The above display device is, A cover window attached to one side of the above-mentioned optical transparent adhesive; and A display member attached to the other side of the above-mentioned optical transparent adhesive; further comprising The above-described optical transparent adhesive is a display device that adheres to a cover window and a display member after dual curing.

Description

Photocurable adhesive composition, optically clear adhesive and display device comprising the same The present invention relates to a photocurable adhesive composition, an optically transparent adhesive, and a display device comprising the same. Various electrical and electronic products, including displays, are composed of a combination of various components, and in these combinations of components, fastening methods using adhesives or pressure-sensitive adhesives are mainly used rather than mechanical fastening methods. In addition, recently, compared to adhesives, which require time for fastening and are cumbersome to store and use, the use of pressure-sensitive adhesives is increasing because, although the fastening strength is somewhat lower, the process is simple and the time required is short. Touchscreen panels generally have a structure in which transparent electrodes and a display module are located beneath a cover window. While these touchscreen panels initially utilized an air gap between the cover window and the transparent electrodes, the full lamination method (or direct bonding method) using optical adhesive materials has now become commonplace. In this full lamination touchscreen panel structure, the optical adhesive materials used to bond each layer are broadly classified into transparent double-sided tape-type optically clear adhesives (hereinafter referred to as 'OCA') and transparent liquid-type optically clear resins. Among these, the above-mentioned optical transparent adhesive possesses inherent elastic properties because it has a film shape. Therefore, when the optical transparent adhesive is applied, bubbles may form in the black or white printed step layer portion on the cover window, and bubbles may also form due to thickness differences of various components provided in the touch panel or display module, as well as steps and curves of the FPCB. In particular, as cases where the internal temperature of a vehicle rises rapidly due to recent abnormal high temperatures increase, there is a growing demand for improved heat resistance under high temperature or high temperature/high humidity conditions for optical transparent adhesives used in automotive display devices. In order to improve the heat resistance of adhesives, adhesives with added acrylate-based crosslinking agents, urethane-based crosslinking agents, epoxy-based crosslinking agents, etc. are being developed. However, while the addition of crosslinking agents increases the crosslinking density and thus prevents the formation of bubbles under high temperature or high temperature/high humidity conditions, the higher the heat resistance, the lower the step coverage characteristics become, which leads to another problem where bubbles form when laminated with cover glass, touch panels, or display modules. Therefore, there is a need to develop a new optical transparent adhesive that possesses excellent step coverage characteristics while exhibiting excellent reliability under high temperature or high temperature/high humidity conditions. All terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains, unless otherwise defined. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise. Additionally, as used herein, "comprises" and/or "comprising" are used in the sense that they do not exclude the presence or addition of one or more other components and/or steps other than the mentioned components and/or steps. In addition, in the numerical ranges "a to b" and "a~b" in this specification, "to" and "~" are defined as ≥ a and ≤ b. In addition, the term adhesive used in the present invention refers to a film form and may refer to a dual-cured film form. Furthermore, the adhesive may refer to an adhesive layer or a laminate in which a substrate (e.g., a release film) is attached to an adhesive layer. In addition, the term "dual curing" as used in this specification includes primary curing and secondary curing, and refers to a process of curing twice under different conditions to produce a photocurable adhesive composition containing a partially polymerized acrylic copolymer in the form of a film. At this time, the primary curing and secondary curing may each be selected from thermal curing and photocuring, and preferably, both the primary curing and secondary curing may be photocuring in which light of a certain wavelength is irradiated to cure. Additionally, the term "step" as used in this specification may refer to a step caused by white or black printing formed on a cover window, a step caused by elements provided on the surface of a display member, or a step caused by a Flexible Printed Circuit Board (FPCB). Additionally, the term "curved portion" as used in this specification refers to a non-flat porti