Optical laminate and flexible display apparatus comprising the same

Abstract

The present disclosure relates to an optical laminate including: a supporting substrate layer; and a hard coating layer located on at least one surface of the supporting substrate layer and including a cured product of a hard coating composition, wherein the hard coating composition includes: a polysiloxane including 70 mol % or more of a structural unit containing a glycidyl group-containing functional group; an elastomer; and a reactive monomer containing at least one functional group capable of cross-linking with the polysiloxane, and the elastomer is contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the polysiloxane. The present disclosure also relates to a flexible display apparatus including the above optical laminate.

Claims

1. An optical laminate comprising a supporting substrate layer; and a hard coating layer located on at least one surface of the supporting substrate layer and comprising a cured product of a hard coating composition, wherein the hard coating composition comprises: a polysiloxane comprising 70 mol % or more of a structural unit containing a glycidyl group-containing functional group represented by the following Chemical Formula 1; an elastomer; and a reactive monomer containing at least one functional group capable of cross-linking with the polysiloxane, and the elastomer is contained in an amount of 5 to 80 parts by weight based on 100 parts by weight of the polysiloxane: ##STR00003## wherein, in Chemical Formula 1, R.sub.a is selected from the group consisting of a substituted or unsubstituted C1 to C6 alkylene group, a substituted or unsubstituted C2 to C20 alkenylene group, a substituted or unsubstituted C2 to C20 alkynylene group, R.sub.bCHCHCOOR.sub.c, R.sub.dOCOCHCHR.sub.e, R.sub.fOR.sub.g, R.sub.hCOOR.sub.i, and R.sub.jOCOR.sub.k, wherein R.sub.b to R.sub.k are each independently a single bond or a substituted or unsubstituted C1 to C6 alkylene group.

2. The optical laminate of claim 1, wherein the structural unit containing the glycidyl group-containing functional group represented by Chemical Formula 1 is represented by the following Chemical Formula 2:
(R.sup.1SiO.sub.3/2)[Chemical Formula 2] wherein, in Chemical Formula 2, R.sup.1 is the glycidyl group-containing functional group represented by Chemical Formula 1.

3. The optical laminate of claim 1, wherein the polysiloxane further comprises at least one repeating unit selected from the group consisting of repeating units represented by the following Chemical Formulae 3 to 6:
(R.sup.2SiO.sub.3/2)[Chemical Formula 3]
(R.sup.3R.sup.4SiO.sub.4/2)[Chemical Formula 4]
(SiO.sub.4/2)[Chemical Formula 5]
(O.sub.1/2R.sup.5)[Chemical Formula 6] wherein, in Chemical Formulae 3 to 6, R.sup.2 to R.sup.5 are each independently a hydrogen atom, an epoxy group, an acryl group, a methacryl group, a halogen group, an amino group, a mercapto group, an acetyl group, a formyl group, a carboxyl group, a nitro group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C7 to C20 arylalkyl group, or a substituted or unsubstituted C7 to C20 alkylaryl group.

4. The optical laminate of claim 1, wherein the polysiloxane has an equivalent weight of the glycidyl group-containing functional group represented by Chemical Formula 1 of 3.0 to 6.3 g/eq.

5. The optical laminate of claim 1, wherein the polysiloxane has a weight average molecular weight of 1000 to 50,000 g/mol, a number average molecular weight of 1000 to 10,000 g/mol, and a molecular weight distribution of 1.0 to 10.0.

6. The optical laminate of claim 1, wherein the elastomer is at least one polyol selected from the group consisting of a polyether-based polyol, a polyester-based polyol, an aliphatic hydrocarbon-based polyol, and a polycarbonate-based polyol.

7. The optical laminate of claim 6, wherein the polyester-based polyol is a polycaprolactone polyol represented by the following Chemical Formula 7: ##STR00004## wherein, in Chemical Formula 7, R.sup.6 is a polyol-derived unit, m is an integer of 1 or more, and f is an integer of 2 or more.

8. The optical laminate of claim 1, wherein the functional group capable of cross-linking with the polysiloxane is selected from the group consisting of an alicyclic epoxy group, a glycidoxy group, and an oxetane group.

9. The optical laminate of claim 1, wherein the reactive monomer comprises at least one selected from the group consisting of bisphenol A diglycidyl ether, 4-vinylcyclohexene dioxide, cyclohexene vinyl monoxide, (3,4-epoxycyclohexyl)methyl 3,4-epoxycyclohexylcarboxylate, 3,4-epoxycyclohexylmethyl methacrylate, 3,4-epoxycyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl)-1,3-dioxolane, bis(3,4-epoxycyclohexylmethyl)adipate, p-butyl phenol glycidyl ether, butyl glycidyl ether, cresyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, diglycidyl ether, butanediol diglycidyl ether, limonene dioxide, vinylcyclohexene dioxide, diethylene glycol diglycidyl ether, 3-methyloxetane, 2-methyloxetane, 3-oxetanol, 2-methyleneoxetane, 3-methyl-3-hydroxynnethyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3,3-oxetanedimethanethiol, 2-ethylhexyloxetane, 4-(3-methyloxetane-3-yl)benzonitrile, N-(2,2-dimethylprophyl)-3-methyl-3-oxetanemethaneamine, N-(1,2-dimethylbutyl)-3-methyl-3-oxetanemethaneamine, xylylene bisoxetane, 3-ethyl-3[{(3-ethyloxetane-3-yl)methoxy}methyl]oxetane, (3-ethyloxetane-3-yl)methyl methacrylate, and 4-[(3-ethyloxetane-3-yl)methoxy]butane-1-ol.

10. The optical laminate of claim 1, wherein the reactive monomer is contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of the polysiloxane.

11. The optical laminate of claim 1, further comprising at least one selected from the group consisting of an initiator, a solvent, an antioxidant, a surfactant, a yellowing inhibitor, an inorganic filler, a lubricant, a flow control agent, and an antifouling agent.

12. The optical laminate of claim 1, wherein a minimum diameter at which cracks do not occur is 2 to 5 in the measurement of outer bending resistance according to JIS K5600-5-1.

13. The optical laminate of claim 1, wherein a thickness thereof is 50 to 250 m.

14. The optical laminate of claim 1, wherein the supporting substrate layer comprises at least one resin selected from the group consisting of a polyester-based resin, a cellulose-based resin, a polycarbonate-based resin, an acryl-based resin, a styrene-based resin, a polyolefin-based resin, a polyimide-based resin, a polyamideimide-based resin, a polyethersulfone-based resin, and a sulfone-based resin.

15. A flexible display apparatus comprising the optical laminate of claim 1.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present invention will be described in more detail in the following examples. However, these examples are only to illustrate the invention, and the scope of the invention is not limited thereto.

(2) Each compound used in the following preparation examples is as follows:

(3) (a1) The polysiloxane: The polysiloxane prepared in the following Synthesis Example 1 was used.

(4) <Synthesis Example 1>

(5) 3-glycidoxypropyltrimethoxysilane (GPTMS, manufactured by Shinetsu) as a silane monomer, water (wherein, GPTMS:water=1 mol:3 mol) and toluene were added to a 1000 mL 3-neck flask, and stirred. A base catalyst (TMAH) was added to the resulting mixed solution in an amount of 1 part by weight based on 100 parts by weight of the silane monomer and reacted at 100 C. to obtain a polysiloxane (Mw: 2700 g/mol, Mn: 2100 g/mol, molecular weight distribution (Mw/Mn): 1.29, epoxy equivalent weight: 5.9 g/eq) containing 100 mol % of glycidoxypropyl modified silicone (GP).
(R.sup.1SiO.sub.3/2).sub.a(R.sup.2SiO.sub.3/2).sub.b(OR).sub.c(1)

(6) (In Chemical Formula 1 above, R.sup.1 is a glycidyl group (each R is a hydrogen atom and R is a methylene group in Chemical Formula 2), a=1, b=0, and c=0.) (a2) The polysiloxane: The polysiloxane prepared in the following Synthesis Example 2 was used.

(7) <Synthesis Example 2>

(8) 250 g of 3-glycidoxypropyltrimethoxysilane (GPTMS, manufactured by Shinetsu) and 140 g of methyltrimethoxysilane (MTMS, manufactured by Shinetsu) as a silane monomer, water (wherein GPTMS:MTMS:water=1 mol:3 mol:0.97 mol) and 200 g of toluene were added to a 1000 mL 3-neck flask, and stirred. A base catalyst (TMAH) was added to the resulting mixed solution in an amount of 1 part by weight based on 100 parts by weight of the silane monomer and reacted at 100 C. to obtain a polysiloxane (Mw: 2300 g/mol, Mn: 1920 g/mol, molecular weight distribution (Mw/Mn): 1.29, epoxy equivalent weight: 2.95 g/eq) containing 62 mol % of glycidoxypropyl modified silicone (GP).
(R.sup.1SiO.sub.3/2).sub.a(R.sup.2SiO.sub.3/2).sub.b(OR).sub.c(1)

(9) (In Chemical Formula above, R.sup.1 is a glycidyl group (each R is a hydrogen atom and R is a methylene group in Chemical Formula 2), R is a hydrogen atom, a=0.62, b=0.37, and c=0.01.)

(10) (a3) The polysiloxane: The polysiloxane prepared in the following Synthesis Example 3 was used.

(11) <Synthesis Example 3>

(12) 350 g of 3-glycidoxypropyltrimethoxysilane (GPTMS, manufactured by Shinetsu) and 61 g of methyltrimethoxysilane (MTMS, manufactured by Shinetsu) as a silane monomer, water (wherein, GPTMS:MTMS:water=1 mol:0.3 mol:0.3 mol) and 200 g of toluene were added to a 1000 mL 3-neck flask, and stirred. A base catalyst (TMAH) was added to the resulting mixed solution in an amount of 1 part by weight based on 100 parts by weight of the silane monomer and reacted at 100 C. to obtain a polysiloxane (Mw: 3200 g/mol, Mn: 2450 g/mol, molecular weight distribution (Mw/Mn): 1.30, epoxy equivalent weight: 4.54 g/eq) containing 76 mol % of glycidoxypropyl modified silicone (GP).
(R.sup.1SiO.sub.3/2).sub.a(R.sup.2SiO.sub.3/2).sub.b(OR).sub.c(1)

(13) (In Chemical Formula above, R.sup.1 is a glycidyl group (each R is a hydrogen atom and R is a methylene group in Chemical Formula 2), R.sup.2 is a methyl group, R is a hydrogen atom, a=0.76, b=0.23, and c=0.01.)

(14) (b) The reactive monomer: Bisphenol A diglycidyl ether (manufactured by Alfa) was used.

(15) (c1) The elastomer: Polycaprolactone diol (Mn=1300 Da, manufactured by Sigma Aldrich) was used.

(16) (c2) The elastomer: Polycarbonate diol (manufactured by Aldrich) was used.

(17) <Examples 1 to 5 and Comparative Examples 1 to 8>

(18) Each hard coating composition was prepared by mixing the following components as shown in Table 1 below. 3 parts by weight of an iodonium-based compound (Omnicat 250, manufactured by BASF) as an initiator and 10 parts by weight of toluene as a solvent were used based on 100 parts by weight of the polysiloxane.

(19) TABLE-US-00001 TABLE 1 Examples Comparative Examples Content (weight %) 1 2 3 4 5 6 7 1 2 3 4 5 6 (a1) Polysiloxane 84 73 55 84 73 91 55 90 (a2) Polysiloxane 87 73 53 (a3) Polysiloxane 74 52 Reactive monomer 8 7 7 4 7 8 7 9 6 8 7 7 Elast- (c1) Polycaprolactone 8 20 38 22 41 20 45 4 4 20 40 omer diol (c2) Polycarbonate 8 diol

(20) <Experimental Examples>

(21) An optical laminate was prepared by using one of the hard coating compositions prepared in the above examples and comparative examples, and then evaluated by the following method. The results are shown in Table 2.

(22) <Preparation of Optical Laminate>

(23) One of the composition prepared in the above examples and comparative examples was applied onto one surface of a polyamideimide film supporting substrate layer of 15 cm20 cm and a thickness of 50 m, and irradiated with ultraviolet rays for 10 seconds using a UV lamp (irradiation amount: 600 mJ/cm.sup.2) to form a hard coating layer having a thickness of 100 m on the supporting substrate layer.

(24) <Evaluation of Physical Properties>

(25) 1) Pencil Hardness

(26) After reciprocating a pencil five times under a load of 1.0 kg using a pencil hardness measuring device according to JIS K5400, the hardness when scratches were not observed was confirmed.

(27) 2) Dent (Pressure Marks)

(28) After reciprocating a pencil five times under a load of 1.0 kg using a pencil hardness measuring device according to JIS K5400, it was confirmed whether or not pressure marks occurred in the path passed. The pencil hardness when pressure marks did not occur was defined as a dent value, which was measured immediately after the reciprocation.

(29) If pressure marks did not occur: O.K.

(30) If pressure marks occurred: N.G.

(31) 3) Scratch Resistance

(32) After steel wool (#000) was mounted on a friction tester and reciprocated 1000 times under a load of 500 gf, the number of flaws was counted with the naked eye, and the scratch resistance was evaluated according to the following criteria.

(33) If the number of flaws is 2 or less: O.K. (Excellent scratch resistance)

(34) If the number of flaws is more than 2: N.G. (Poor scratch resistance)

(35) 4) Dynamic Inner Bending Resistance

(36) The hard coating layer was inwardly folded to face inward with a diameter of 5 mm, and unfolded. This was repeated 200,000 times, and the inner bending resistance was evaluated according to the following criteria by confirming whether or not a crack occurred.

(37) If a crack did not occur: O.K.

(38) If a crack occurred: N.G.

(39) 5) Dynamic Outer Bending Resistance

(40) The hard coating layer was outwardly folded with a diameter of 6 mm, that is, the supporting substrate layer on which the hard coating layer was not formed was inwardly folded, and unfolded. This was repeated 200,000 times, and the outer bending resistance was evaluated according to the following criteria by confirming whether or not a crack occurred.

(41) If a crack did not occur: O.K.

(42) If a crack occurred: N.G.

(43) Outer bending resistance (Mandrel bend test)

(44) 6) Inner/Outer Bending Resistance (Mandrel Bend Test)

(45) In order to evaluate flexibility of the optical laminate, each film of examples and comparative examples was mounted in mandrels of various diameters, and wound such that the hard coating layer faced inward according to JIS K5600-5-1. The occurrence of cracks and a minimum diameter at which cracks did not occur were measured to evaluate the inner bending resistance.

(46) The outer bending resistance was evaluated in the same manner as above, except that the hard coating layer of the optical laminate was wound so as to face outward.

(47) TABLE-US-00002 TABLE 2 Dynamic Dynamic Inner Outer inner outer bending bending Pencil Scratch bending bending resistance resistance Hardness Dent resistance resistance resistance (Mandrel) (Mandrel) Ex. 1 8 H 8 H O.K. O.K. O.K. 2 4 Ex. 2 8 H 8 H O.K. O.K. O.K. 2 3 Ex. 3 7 H 7 H O.K. O.K. O.K. 2 2.5 Ex. 4 8 H 6 H O.K. O.K. O.K. 2 3 Ex. 5 6 H 6 H O.K. O.K. O.K. 2 2.5 Ex. 6 8 H 8 H O.K. O.K. O.K. 2 4 Ex. 7 8 H 8 H O.K. O.K. O.K. 2 3 Comp. Ex. 1 8 H 8 H O.K. O.K. N.G. 2 6 Comp. Ex. 2 8 H 5 H O.K. O.K. O.K. 2 3 Comp. Ex. 3 4 H 3 H O.K. O.K. O.K. 2 2.5 Comp. Ex. 4 5 H 5 H O.K. O.K. N.G. 2 6 Comp. Ex. 5 4 H 4 H O.K. O.K. O.K. 2 4 Comp. Ex. 6 3 H 3 H O.K. O.K. N.G. 2 4

(48) Referring to Table 2 above, the optical laminates prepared using one of the hard coating compositions of Examples 1 to 5 exhibited flexibility and excellent resistance to cracks due to mechanical stress while having high surface hardness and excellent scratch resistance. In addition to having resistance to scratches, a dent due to a constant load did not occur. In Example 3, the hardness characteristics were relatively lower than those of the other examples by applying a relatively large amount of the elastomer, but both the hardness and the flexibility were improved as compared with comparative examples. In Example 4 in which the content based on 100 parts by weight of the polysiloxane was low in the hard coating composition, the dent property was relatively deteriorated, but both the hardness and the flexibility were improved as compared with the comparative examples.

(49) On the other hand, the optical laminate prepared using the hard coating composition of Comparative Example 1 which does not contain an elastomer exhibited the same level of surface hardness and scratch resistance as those of the examples, but showed significantly deteriorated outer bending resistance due to a lack of flexibility. The optical laminate prepared using the hard coating composition of Comparative Example 2 which did not contain a reactive monomer exhibited the same level of surface hardness, scratch resistance and outer bending resistance as those of the examples. However, when pencil hardness was measured, it was confirmed that dent (pressure marks) occurred and the pressure marks were not restored well as compared with the examples.

(50) Comparative Example 3, which did not satisfy the mixing ratio of the polysiloxane and the elastomer in the hard coating composition, had significantly lowered hardness characteristics as compared with Examples 1 to 3.

(51) Comparative Examples 4 to 6, which did not satisfy the conditions of the polysiloxane, had significantly lowered hardness as compared with Examples 1 to 3, and the outer bending resistance was also deteriorated.