KR-20260062177-A - Photocurable adhesive composition, optically clear adhesive and display device manufactured using the same

KR20260062177AKR 20260062177 AKR20260062177 AKR 20260062177AKR-20260062177-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 primary UV curing, so that no bubbles are generated in step or curved parts, and exhibits excellent elastic properties after secondary UV curing, thereby suppressing waviness caused by pressing, etc. in the final product.

Inventors

탁명호
김민정
전형빈
최형진
남병기

Assignees

주식회사 테이팩스

Dates

Publication Date: 20260507
Application Date: 20241025

Claims (14)

After first curing, the step coverage at a thickness of 100㎛ is 20㎛ or more, and after second curing, the elastic modulus (EIT) measured by indentation at a thickness of 75㎛ and a temperature of 25℃ with a load of 500 nN for 30 seconds is 0.5 MPa Lee Sang-in, optical transparent adhesive.
In claim 1, 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.
In claim 1, The above-mentioned optical transparent adhesive comprises a partially polymerized acrylic copolymer, and The above partially polymerized acrylic copolymer is an optically transparent adhesive comprising a structural unit derived from a compound represented by the following chemical formula 1. [Chemical Formula 1]
In claim 3, The above partially polymerized acrylic copolymer is, Structural unit derived from a low-temperature glass transition (meth)acrylate monomer having a glass transition temperature of 50°C or lower of the homopolymer; Structural units derived from high-temperature glass transition (meth)acrylate monomers having a glass transition temperature of greater than 50°C of the homopolymer; and An optically transparent adhesive further comprising a structural unit derived from a (meth)acrylate monomer having a hydrophilic group.
In claim 4, The above-mentioned optical transparent adhesive is an optical transparent adhesive further comprising a compound represented by the following chemical formula 1. [Chemical Formula 1]
A display device comprising an optically transparent adhesive according to any one of claims 1 to 5.
In claim 6, 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 first cured before being adhered to a cover window and a display member, and secondarily cured after being adhered to a cover window and a display member, and a display device in which no wavy pattern occurs after secondary curing.
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 8, 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 9, The above photocurable adhesive composition further comprises a compound represented by the following chemical formula 1. [Chemical Formula 1]
In claim 8, The cured product of the above-mentioned photocurable adhesive composition is, After first curing, the step coverage at a thickness of 100㎛ is 20㎛ or more, and after second curing, the elastic modulus (EIT) measured by indentation at a thickness of 75㎛ and a temperature of 25℃ with a load of 500 nN for 30 seconds is 0.5 MPa A photocurable adhesive composition.
In claim 11, 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 A photocurable adhesive composition, 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 a cured product of a photocurable adhesive composition of any one of claims 8 to 12.
In claim 13, The above display device is, A cover window adhered to one surface of the cured product of the above-mentioned photocurable adhesive composition; and A display member further comprising a cured surface of the above-mentioned photocurable adhesive composition and a cured product thereof; A display device in which the cured product of the above-mentioned photocurable adhesive composition is first cured before being adhered to a cover window and a display member, is secondarily cured after being adhered to a cover window and a display member, and does not produce wavy patterns after the second curing.

Description

Photocurable adhesive composition, optically clear adhesive and display device manufactured using 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 has a film shape and therefore possesses inherent elastic properties. Consequently, 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 order to prevent defects caused by the above bubbles, optical transparent adhesives with improved step coverage characteristics are being developed. However, as the step coverage characteristics of the adhesive are improved, the elastic properties decrease, and consequently, another problem arises in which waviness defects caused by pressing of the optical transparent adhesive appear in the final product. Therefore, there is a need to develop a new optical transparent adhesive that possesses excellent step coverage characteristics without compromising elastic properties, thereby preventing waviness from appearing in the final product. 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-like form and refers to a primary cured state or a secondary cured state. 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. Additionally, as used in this specification, the term "primary curing" refers to a process of curing a photocurable adhesive composition comprising a partially polymerized acrylic copolymer to produce it in the form of a film, and "secondary curing" refers to a process of further curing it after primary curing. 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 portion on a cover window or display member, and may be, for example, a central folding portion or a side edge portion. In addition, the term "wavyness" as used in this specification refers to a phenomenon in which a wavy or orange peel-like shape is visible to the naked eye on the screen portion of a display device after the adhesive forms a laminate with the cover window and the display member and undergoes secondary curing. Additionally, the term "light" as used in