Hard coating film
Disclosed herein is a hard coating film, which exhibits high hardness and excellent properties without a supporting substrate. The hard coating film can find useful applications in various fields thanks to its excellent hardness, scratch resistance, transparency, durability, light resistance, light transmittance, and the like.
1. A single-layered substrate-less hard coating film, comprising:
a photocurable crosslinking copolymer; and
inorganic particles dispersed in the photocurable crosslinking copolymer,
wherein the photocurable crosslinking copolymer is a copolymer in which a tri- to hexa-functional acrylate monomer is crosslinked with a photocurable elastic polymer, and the photocurable crosslinking copolymer includes 5 to 20 weight parts of the photocurable elastic polymer and 80 to 95 weight parts of the tri- to hexa-functional acrylate monomer based on 100 weight parts thereof,
wherein the photocurable elastic polymer comprises a polyrotaxane,
wherein the polyrotaxane comprises a cyclic moiety (macrocycle) in which lactone compounds with a (meth)acrylate moiety conjugated to the end thereof are bonded to each other; a thread moiety held within the macrocycle; and stoppers provided at both ends of the thread moiety so as to prevent dissociation of the macrocycle, and
wherein the hard coating film exhibits a pencil hardness of 7H or more at a load of 1 kg.
2. The hard coating film of claim 1 , wherein the photocurable elastic polymer has an elongation of 15 to 200%, as measured according to ASTM D638.
3. The hard coating film of claim 1 , wherein the hard coating film includes 40 to 90 weight parts of the photocurable crosslinking copolymer and 10 to 60 weight parts of the inorganic particles, based on 100 weight parts thereof.
4. The hard coating film of claim 1 , wherein the inorganic particles have a particle diameter of 100 nm or less.
5. The hard coating film of claim 1 , wherein the inorganic particles include at least one selected from the group consisting of silica nanoparticles, aluminum oxide nanoparticles, titanium oxide nanoparticles and zinc oxide nanopaticles.
6. The hard coating film of claim 1 , wherein the tri- to hexa-functional acrylate monomer includes at least one selected from the group consisting of trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxytriacrylate (TMPEOTA), glycerin propoxylated triacrylate (GPTA), pentaerythritol tetraacrylate (PETA), and dipentaerythritol hexaacrylate (DPHA).
7. The hard coating film of claim 1 , wherein the hard coating film does not crack when a 22 g steel ball is freely dropped 10 times thereon from a height of 50 cm.
8. The hard coating film of claim 1 , wherein the hard coating film allows two or less scratches to appear thereon after it is doubly rubbed 400 times with a steel wool #0000 under a load of 500 g.
9. The hard coating film of claim 1 , having a light transmittance of 91% or more, a haze of 0.4 or less and a color b* value of 1.0 or less.
10. The hard coating film of claim 1 , the difference between an initial color b* value and a color b* value after exposure to UV B for 72 hrs is 0.5 or less.
11. The hard coating film of claim 1 , wherein the hard coating film has a thickness of 50 to 500 μm.
12. The hard coating film of claim 1 , wherein when the hard coating film is disposed on a plane after exposure to a temperature of 50° C. or more at a humidity of 80% or more for 70 hrs or more, each edge or side of the hard coating film is spaced apart from the plane by 1.0 mm or less, maximally.
13. The hard coating film of claim 1 , further comprising at least one selected from the group consisting of a plastic resin film, an adhesive film, a releasable film, an electrically conductive film, an electrically conductive layer, a curable resin layer, a non-conductive film, a metal mesh layer, and a patterned metal layer, each of which is attached to one side thereof.