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US-12619010-B2 - Optical multilayer structure and method of manufacturing the same

US12619010B2US 12619010 B2US12619010 B2US 12619010B2US-12619010-B2

Abstract

An optical multilayer structure including a substrate; a shatterproof layer which is formed on at least one surface of the substrate and includes a polyimide film including a polyimide precursor, a polyimide, or a combination thereof including a structure of the following Chemical Formula 1, and inorganic particles; and a hard coating layer formed on the other surface of the substrate: wherein R 1 and R 2 are independently of each other C 1-5 alkyl which is unsubstituted or substituted with one or more halogens; R 3 and R 4 are independently of each other C 6-10 aryl which is unsubstituted or substituted with one or more halogens; L 1 and L 2 are independently of each other C 1-10 alkylene; and x and y are independently of each other an integer of 1 or more.

Inventors

  • Cheol Min Yun
  • Chun Ho Kim

Assignees

  • SK INNOVATION CO., LTD.

Dates

Publication Date
20260505
Application Date
20230524
Priority Date
20220525

Claims (14)

  1. 1 . An optical multilayer structure comprising: an ultrathin tempered glass (UTG) substrate; a shatterproof layer which is formed on one surface of the ultrathin tempered glass substrate and comprises a polyimide film comprising a polyimide precursor, a polyimide, or a combination thereof comprising a structure of the following Chemical Formula 1, and inorganic particles; and a hard coating layer formed directly on the other surface of the ultrathin tempered glass substrate: wherein R 1 and R 2 are independently of each other C 1-5 alkyl which is unsubstituted or substituted with one or more halogens; R 3 and R 4 are independently of each other C 6-10 aryl which is unsubstituted or substituted with one or more halogens; L 1 and L 2 are independently of each other C 1-10 alkylene; and x and y are independently of each other an integer of 1 or more, wherein a curl amount of opposing ends of the optical multilayer structure is less than 0.5 mm, wherein the curl amount is calculated as an average value of the values measured at each of the opposing ends.
  2. 2 . The optical multilayer structure of claim 1 , wherein the polyimide precursor, the polyimide, or the combination thereof further comprises a unit derived from a diamine represented by the following Chemical Formula 2: wherein R 11 and R 21 are independently of each other hydrogen or a C 1-20 monovalent organic group; L 11 is —SO 2 —, —O—, or —C(═O)O—, or a C 1-20 divalent organic group comprising any one or more of these bonds; and Chemical Formula 2 does not comprise a fluorine atom.
  3. 3 . The optical multilayer structure of claim 1 , wherein the polyimide precursor, the polyimide, or the combination thereof further comprises a unit derived from a fluorine-based diamine.
  4. 4 . The optical multilayer structure of claim 3 , wherein the fluorine-based diamine comprises one or more selected from the group consisting of 2,2′-bis(trifluoromethyl)benzidine (TFMB), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), 2,2-bis(4-aminophenyl)hexafluoropropane (BAHF), 2,2′-bis(trifluoromethyl)-4,4′-diaminodiphenylether, 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene and mixtures thereof.
  5. 5 . The optical multilayer structure of claim 1 , wherein R 1 and R 2 are independently of each other C 1-3 alkyl which is unsubstituted or substituted with one or more halogens; R 3 and R 4 are independently of each other C 6-8 aryl which is unsubstituted or substituted with one or more halogens; and L 1 and L 2 are independently of each other C 1-5 alkylene.
  6. 6 . The optical multilayer structure of claim 1 , wherein the structure of Chemical Formula 1 is a structure of the following Chemical Formula 3: wherein L 1 and L 2 are independently of each other C 1-10 alkylene; and x and y are independently of each other an integer of 1 or more.
  7. 7 . The optical multilayer structure of claim 2 , wherein R 11 and R 21 are independently of each other hydrogen or a C 1-10 monovalent organic group; and L 11 is —SO 2 —, —O—, or —C(═O)O—, or a C 1-15 divalent organic group comprising any one or more of these bonds.
  8. 8 . The optical multilayer structure of claim 2 , wherein L 11 is —SO 2 —, —O—, or —C(═O)O—, or a combination of any one or more of —SO 2 —, —O—, or —C(═O)O— and any one or more selected from the group consisting of C 1-10 alkyl, C 5-18 cycloalkylene, and C 6-18 arylene.
  9. 9 . The optical multilayer structure of claim 1 , wherein the inorganic particles comprise silica, zirconium oxide, titanium oxide, zinc oxide, zinc sulfide, chromium oxide, barium titanate, or a combination thereof.
  10. 10 . The optical multilayer structure of claim 1 , wherein the hard coating layer comprises a siloxane-based compound comprising an epoxy group.
  11. 11 . A method of manufacturing the optical multilayer structure according to claim 1 , the method comprising: applying a polyimide precursor composition on one surface of the ultrathin tempered glass substrate and drying the composition to form a shatterproof layer; and applying a composition for forming a hard coating layer directly on the other surface of the glass substrate and curing the composition to form a hard coating layer.
  12. 12 . A window cover film comprising the optical multilayer structure according to claim 1 .
  13. 13 . A flexible display panel comprising the window cover film according to claim 12 .
  14. 14 . The optical multilayer structure of claim 1 , wherein the inorganic particles comprise silica.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Korean Patent Application No. 10-2022-0063876, filed May 25, 2022, Korean Patent Application No. 10-2022-0063866, filed May 25, 2022, and Korean Patent Application No. 10-2023-0054300, filed Apr. 25, 2023, the disclosures of each of which are hereby incorporated by reference in their entireties. BACKGROUND OF THE INVENTION Field of the Invention The following disclosure relates to an optical multilayer structure and a method of manufacturing the same. Description of Related Art A polyimide film is a material for a substrate, a cover window, and the like of a display device, and is attracting attention as a next-generation material which may replace tempered glass. In order to apply a film to a display device, it is essential to improve intrinsic yellow index characteristics and impart colorless and transparent characteristics, and furthermore, in order to make the film applicable to a foldable or flexible display device, mechanical properties should be also improved, and thus, the required performance of the polyimide film for a display device is gradually increased. In particular, it is important to design a flexible display device which may be bent or folded when the user wants as a flexible structure so that the device is not easily broken upon external impact or during a bending or folding process. SUMMARY OF THE INVENTION An embodiment of the present disclosure is directed to providing a multilayer structure comprising: a structure comprising a polyimide shatterproof layer having a relaxed thermal expansion-shrinkage behavior formed on one surface of a substrate and a hard coating layer formed on the other surface of the substrate; or a structure in which the shatterproof layers are formed on both surfaces of the substrate, wherein curling is excellently improved and surface hardness is significantly increased. Another embodiment of the present disclosure is directed to providing a method of manufacturing the optical multilayer structure. Still another embodiment of the present disclosure is directed to providing a window cover film comprising the optical multilayer structure and a flexible display panel comprising the same. In one general aspect, an optical multilayer structure comprises: a substrate;a shatterproof layer which is formed on one surface of the substrate and comprises a polyimide film comprising a polyimide precursor, a polyimide, or a combination thereof comprising a structure of the following Chemical Formula 1, and inorganic particles; anda hard coating layer formed on the other surface of the substrate: whereinR4 and R2 are independently of each other C1-5 alkyl which is unsubstituted or substituted with one or more halogens;R3 and R4 are independently of each other C6-10 aryl which is unsubstituted or substituted with one or more halogens;L4 and L2 are independently of each other C1-10 alkylene; andx and y are independently of each other an integer of 1 or more. In one embodiment, the optical multilayer structure may further comprise a shatterproof layer between the substrate and the hard coating layer. In another general aspect, a method of manufacturing the optical multilayer structure according to the implementation comprises: applying a polyimide precursor composition on one surface of a substrate and drying the composition to form a shatterproof layer; and applying a composition for forming a hard coating layer on the other surface of the substrate and curing the composition to form a hard coating layer. In another general aspect, a method of manufacturing the optical multilayer structure according to the implementation comprises: applying a polyimide precursor composition on both surfaces of a substrate (the one surface of the substrate and the other surface of the substrate) and drying the composition to form a first shatterproof layer on the one surface of the substrate and a second shatterproof layer on the other surface of the substrate; and applying a composition for forming a hard coating layer on any one of the first shatterproof layer or the second shatterproof layer formed on the substrate and curing the composition to form a hard coating layer. In another general aspect, a window cover film comprises the optical multilayer structure according to the implementation. In still another general aspect, a flexible display panel comprises the window cover film according to the implementation. Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 schematically show a structure of an optical multilayer structure according to one implementation. Detailed Description of Main Elements 100: Optical multilayer structure10: Display element20: Substrate30: Shatterproof layer40: Hard coating layer DESCRIPTION OF THE INVENTION The embodiments described in the present specification may be modified in man