WO2018217046A1 - Optically transparent adhesive sheet - Google Patents

Abstract

The present invention provides: an optically transparent adhesive film comprising a (meth)acrylate syrup, which is a resin syrup prepared by partially polymerizing (meth)acrylate monomers, and a photoinitiator, wherein the sheet has a stress relaxation rate of 0.02-0.10 after performing primary ultraviolet cross-linking at 70°C, and has a stress relaxation rate of 0.3-0.6 after performing secondary ultraviolet cross-linking at the same temperature as the temperature of the primary ultraviolet cross-linking; a flat panel display apparatus comprising the same; and a composition for preparing the same.

Description

Optical Transparent Adhesive Sheet

The present invention relates to an optically transparent adhesive sheet, a flat panel display device comprising the same, and a composition for manufacturing the same.

In image display modules of electronic devices such as mobile handheld devices, computer displays and touch panels, glass or plastic films are laminated as surface protective layers. This surface protection layer is fixed to the image display module or touch panel by applying a frame-shaped tape or adhesive to the margin outside the image display portion or outside the active area of the touch panel. As a result, a gap is formed between the active area of the image display portion or the touch panel and the surface protective layer.

In order to promote transparency and improve contrast, there has been a trend in the industry to replace the gap between the image display module or touch panel and the surface protection layer with a transparent material that is nearly identical in refractive index with these materials. Exemplary transparent materials include, but are not limited to, optical adhesive films (OCA films), pressure sensitive adhesives, adhesives, silicon gels, and the like. In the case of using an adhesive, for example, if a defect occurs after laminating the surface protective layer and the image display module, it is difficult to separate and replace the surface protective layer. Silicone gels have reliability problems due to their low adhesion. On the other hand, the pressure-sensitive adhesive (for example, the pressure-sensitive adhesive sheet) is capable of re-lamination in spite of sufficiently high adhesion, but it is difficult to apply uniformly due to the liquid type by the solvent, and lifted by the remaining solvent. There is a problem that a phenomenon occurs.

The surface of the adherend, such as an image display module, optical member or surface protective layer, is sometimes non-uniform. The surface of the surface protective layer, in particular in contact with an adhesive film or adhesive sheet, is often subjected to printing for decorative or shading purposes. In some cases, the printed portion generates a step of at least 10 μm in height on the surface of the surface protective layer. One potential problem in laminating an image display module or touch panel with a surface protective layer using an optical adhesive film is that the optical adhesive film may not be sufficiently matched to the stage and there may be gaps on or around the stage. It can be triggered.

Conventional Korean Patent Laid-Open Publication No. 10-2016-0011785 discloses a transparent photocurable pressure-sensitive adhesive composition, but due to the non-uniform surface of the adhesive, there is a lack of end embedding and step resilience during bonding. There was a problem that occurred.

In order to solve the above problems, the object of the present invention is to minimize the lifting phenomenon from the surface of the adherend after curing, and to provide an optically transparent adhesive sheet excellent in adhesion, step filling and durability.

The present invention is an optically transparent adhesive sheet comprising a (meth) acrylic copolymer, a photoinitiator and an acrylate monomer, wherein the optically transparent adhesive sheet has a stress relaxation ratio of 0.02 to 0.10 after primary ultraviolet crosslinking at 70 ° C, It provides an optically transparent adhesive sheet characterized in that the stress relaxation ratio after the second ultraviolet crosslinking at the same temperature as the first ultraviolet crosslinking is 0.3 to 0.6.

 In addition, the present invention is a composition comprising a (meth) acrylate resin syrup, a photoinitiator and a (meth) acrylate monomer which is a resin syrup prepared by partially polymerizing a (meth) acrylate monomer, the optically transparent adhesive sheet described above It provides a composition for preparing.

In addition, the present invention provides a flat panel display device including the optically transparent adhesive sheet described above.

In the film of the present invention, the stress relaxation ratio after primary UV crosslinking at 70 ° C. is 0.02 to 0.10, thereby providing excellent end embedding and step breakability, and the stress relaxation ratio after secondary UV crosslinking at 70 ° C. is 0.3. Designed to 0.6 to minimize the lifting phenomenon from the surface of the adherend, it is possible to provide an energy-curable inorganic adhesive film excellent in step fillability and durability.

The present invention relates to an optically transparent adhesive film and a composition for producing the same. The optically transparent adhesive film of the present invention may be an inorganic film. In addition, the composition of the present invention may be one containing a (meth) acrylate copolymer, a photoinitiator and a (meth) acrylate monomer. The optically transparent adhesive film of the present invention may include a (meth) acrylic copolymer, a photoinitiator and an acrylate monomer, and in the present invention, that the optically transparent adhesive film includes the composition may mean that the composition is prepared from the composition. have. In the optically transparent adhesive sheet of the present invention prepared from the composition, the optically transparent adhesive sheet has a stress relaxation ratio of 0.02 to 0.10 after the first ultraviolet crosslinking at 70 ° C., and is performed at the same temperature as that of the first ultraviolet crosslinking. The stress relaxation ratio after the second ultraviolet crosslinking is characterized in that 0.3 to 0.6, it is excellent in the end buried property and step overcomeability, it is possible to minimize the lifting phenomenon from the surface of the adherend after curing.

The present invention is a composition comprising a (meth) acrylate resin syrup, a photoinitiator and a (meth) acrylate monomer, which is a resin syrup prepared by partially polymerizing a (meth) acrylate monomer, wherein the optically transparent adhesive sheet is prepared. To provide a composition for the purpose, the composition of the present invention, the stress relaxation ratio after the first ultraviolet crosslinking at 70 ℃ is 0.02 to 0.10, the second ultraviolet crosslinking at the same temperature as the temperature of the first ultraviolet crosslinking When the post-stress relaxation ratio satisfies 0.3 to 0.6, it is possible to secure end embedding and step resilience due to cohesion, adhesiveness, and durability improvement in the pressure-sensitive adhesive, and minimize the lifting phenomenon from the surface of the adhesive.

Hereinafter, the configuration of the present invention will be described in detail.

(Meth) acrylate syrup

In the present invention, (meth) acrylate means "acrylate", "methacrylate" or both. When (meth) acrylate syrup is included, it can contribute to the cohesion, adhesion and durability of the adhesive.

The (meth) acrylate syrup of the present invention may comprise i) an acrylate comprising a hydroxy group and ii) a monofunctional (meth) acrylate monomer. In the case where the i) acrylate monomer including a hydroxyl group is included, it may contribute to the improvement of cohesion and adhesion. The i) acrylate containing a hydroxy group is not limited in kind as long as it includes a hydroxy group, the alkyl acrylate monomer containing a hydroxy group is specifically, for example, 2-hydroxyethyl acrylate, 2-hydroxy Propyl acrylate, 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, 6-hydroxyhexyl acrylate, 8-hydroxyoctyl acrylate, 2-hydroxyethylene glycol acrylate and 2-hydroxypropylene Glycol acrylate and the like.

The ii) monofunctional (meth) acrylate monomer is not limited in kind as long as it is a monofunctional monomer known in the art, specifically, for example, ethylhexyl (meth) acrylate, dodecyl (meth) Acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) Acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl ( Meth) acrylate, 2-ethylbutyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (Meth) acrylate , Acrylic acid, methacrylic acid, 2- (meth) acryloyloxy acetic acid, 3- (meth) acryloyloxy propyl acid, 4- (meth) acryloyloxy butyl acid, 2-hydroxyethyl (meth) Acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 2-hydroxy It may include one or more selected from the group consisting of hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate and the like. It is more preferable when it contains 1 or more types chosen from the group which consists of ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, isobornyl (meth) acrylate, and cyclohexyl (meth) acrylate.

The i) acrylate containing a hydroxy group may include 5 to 20% by weight relative to the total weight of the copolymer comprising the i) acrylate containing a hydroxy group and the ii) monofunctional (meth) acrylate monomer, 5 If it is less than the weight%, the durability reliability may be lowered, such as cohesive failure occurs under high temperature and / or high humidity conditions, and if it exceeds 20% by weight, wettability and adhesion may be reduced due to the decrease in compatibility.

In the present invention, the (meth) acrylate syrup may have a weight average molecular weight of 600,000 or more and 1 million or less, more preferably 600,000 or more and 800,000 or less. When the weight average molecular weight of the (meth) acrylate syrup of the present invention satisfies the above range, it can be expected to improve adhesion characteristics, wettability, and durability.

Photoinitiator

The optically transparent adhesive sheet of the present invention includes a photoinitiator in order to efficiently induce the reaction of the radical polymerizable group.

The photoinitiator is not particularly limited as long as the photoinitiator is a general initiator capable of generating radicals by irradiation with ultraviolet rays and thus may initiate photopolymerization, and photopolymerization initiators known in the art may be used. Specifically, a benzoin type initiator, a hydroxy ketone type initiator, an amino ketone type initiator, and / or a phosphine oxide type initiator etc. are mentioned, More specifically, 2, 2- dimethoxy- 1, 2- diphenyl ethane- 1 is mentioned. Di-((2,4,6-trimethylbenzoyl) phosphine oxide),-(2,2-Dimethoxy-1,2-diphenylethan-1-one) diphenyl (2,4,6-trimethylmenzoyl) phosphine oxide, Hydroxycyclohexyl phenyl ketone, Hydroxy methyl phenyl ketone, benzoylformic acid, 1,4-dibenzoylbenzene (1,4-Dibenzoylbenzene), benzyl Etc. can be mentioned.

The photoinitiator may include two or more selected from the group consisting of a polyfunctional benzoyl compound initiator, a benzophenone initiator, a benzoin initiator, a hydroxyketone initiator, an amino ketone initiator, and / or a phosphine oxide initiator. Can be. The multifunctional benzoyl compound-based initiator 100% benzoyl formic acid and Coronate-HXR in a 1: 1 equivalent ratio, the polyfunctional benzoyl compound may be formed through a urethane bond reaction. Preferably polyfunctional benzoyl compound, benzophenone acryl (VISIOMER6973, ebonic), 2,2-dimethoxy-1,2-diphenylethan-1-one (2,2-Dimethoxy-1,2-diphenylethan-1 -one) Diphenyl (2,4,6-trimethylmenzoyl) phosphine oxide (Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide), hydroxy cyclohexyl phenyl ketone, hydroxy methyl phenyl It may include two or more selected from the group consisting of hydroxy methyl phenyl ketone, benzoylformic acid, 1,4-dibenzoylbenzene, and / or benzyl, and the like. have.

The photoinitiator may be included in an amount of 0.2 to 4 parts by weight, more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the total amount of the acrylate monomer and the monofunctional (meth) acrylate monomer including the hydroxy group.

In addition, the photoinitiator may be included in 0.2 to 4 parts by weight, more preferably 0.5 to 2 parts by weight based on 100 parts by weight of (meth) acrylate syrup.

When the photoinitiator is included in the above range, even though the photoinitiator is added, the problem is insignificant, and the physical properties such as durability, reliability, and transparency may be improved.

additive

Method for producing an optically transparent adhesive sheet of the present invention can be carried out by a method commonly used in this field except as described above. At this time, the molecular weight modifier, isocyanate crosslinking agent, catalyst and the like used in this field may be used without limitation.

The method of applying the optically transparent adhesive sheet of the present invention is not particularly limited, and after applying the optically transparent adhesive sheet, it is cured through light irradiation. In the present application, for example, when applying an ultraviolet irradiation method, the ultraviolet irradiation may be performed using a means such as a high pressure mercury lamp, an electrodeless lamp or a xenon lamp.

Further, before or after the light irradiation process, an appropriate aging process may be conducted to induce reaction of the functional group of the crosslinking agent in the composition with the thermosetting functional group of the polymer, and the conditions in the process are not particularly limited as long as an appropriate crosslinking reaction can occur. .

In the optically transparent adhesive sheet of the present invention, for example, an optical film such as a polarizing film, a retardation film, an anti-glare film, a wide viewing angle compensation film, or a brightness enhancement film is laminated on each other, or the optical film or the laminate thereof is displayed on a display panel or the like. It can be used to attach to the same adherend.

In particular, the optically transparent adhesive sheet of the present invention can be preferably used in a flexible display device.

In addition, the manufacturing method of the optically transparent adhesive sheet can be used without limitation methods known in the art.

Provided is a flat panel display device comprising an optically transparent adhesive inorganic material film formed from the optically transparent adhesive inorganic material composition of the present invention.

The flat panel display is more preferably a flexible display device.

Hereinafter, the present invention will be described in more detail using examples and comparative examples. However, the following examples are provided to illustrate the present invention, and the present invention is not limited to the following examples and may be variously modified and changed.

Preparation Example: Preparation of (meth) acrylate Syrup

Preparation Example 1

30% by weight of 2-ethylhexyl acrylate (2-EHA) monomer, 25% by weight of ethylhexyl methacrylate (EHMA) monomer, isobornyl in a 1L reactor equipped with a refrigeration system for easy reflux of nitrogen gas After adding a monomer mixture consisting of 30% by weight of acrylate (IBOA) monomer and 10% by weight of 2-hydroxyethyl acrylate (2-HEA) monomer, purge nitrogen gas for 1 hour to remove oxygen, and then 80 ° C. Was maintained. After uniformly mixing the monomer mixture, 1.0 part by weight of DMPA (2,2-Dimethoxy-2-phenylacetophenone) was added as a photoinitiator. After stirring, the UV lamp (10mW) was irradiated to prepare a (meth) acrylate syrup of 25% solids.

Preparation Examples 2 to 4

To carry out the same as in Preparation Example 1, to prepare a (meth) acrylate syrup in the composition of Table 1.

Test Example 1. Evaluation of weight average molecular weight and molecular weight distribution of (meth) acrylate syrup

The weight average molecular weight and molecular weight distribution of (meth) acrylate syrup were measured on condition of the following using GPC. The measurement result was converted into the calibration curve using standard polystyrene of Agilent system.

 <Weight average molecular weight measurement conditions>

Meter: Agilent GPC (Agilent 1200 series, USA)

Column: Connect 2 PL Mixed B

Column temperature: 40 ℃

Eluent: tetrahydrofuran

Flow rate: 1.0mL / min

Concentration: ~ 1mg / mL (100 μL injection)

division	(Meth) acrylate monomer (% by weight)						Photoinitiator (parts by weight)	% Of reaction	Weight average molecular weight (unit: only)
	EHA	OA	EHMA	IBOA	CMA	2-HEA
Preparation Example 1 (A1)	30		25	30		15	One	25	70
Preparation Example 2 (A2)		30	25	30		15	One	27	65
Preparation Example 3 (A3)	30		25		30	15	One	26	60
Preparation Example 4 (A4)	30	20	45	45		5	One	27	71
EHA: ethylhexyl acrylate OA: octyl acrylate EHMA: ethylhexyl methacrylate IBOA: isobornyl acrylate CMA: cyclohexyl methacrylate 2-HEA: 2-hydroxyethyl acrylate photoinitiator: hydroxy cyclohexylphenyl ketone

Examples 1-4 and Comparative Examples 1-4

The (meth) acrylate syrup and the photoinitiator content of the preparation example were mixed in the composition of Table 2 below to prepare a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition prepared above was applied on a release film coated with a silicone release agent to have a thickness of 150 μm, the release film was bonded thereto, and a pressure-sensitive adhesive sheet was prepared. After the first UV irradiation, the sheet was completed.

		Example						Comparative example
		One	2	3	4	5	6	One	2	3	4
(Meth) acrylate syrup	Kinds	A1	A2	A3	A4	A1	A1	A1	A1	A1	A1
	content	100	100	100	100	100	100	100	100	100	100
Photoinitiator (parts by weight)	DMPA	1.0	1.0	1.0	1.0			2.0		1.0	1.0
	TPO					1.0	1.0
	B-1	1.0	1.0	1.0	1.0	0.5	1.0		1.0	0.1	4.0
UV dose (J / cm 2 )	Primary	3	3	3	3	3	3	3	3	3	3
	Secondary	3	3	3	3	3	3	3	3	3	3
DMPA: 2,2-Dimethoxy-2-phenylacetophenoneTPO: Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide) B-1: Benzoylformic acid + Coronate-HXR 1: 1 equivalent

Test Example 2. Adhesion evaluation

After peeling the release film of one side of the adhesive sheet prepared in Example or Comparative Example and corona treatment and bonding to 38um PET film and pressure-sensitive adhesive surface and cut to 25mm in width, 100mm in length to prepare a specimen. Next, the release film adhered to the PET / adhesive layer structure is peeled off, and the pressure-sensitive adhesive sheet is attached to the alkali glass using a 2 kg roller in accordance with JIS Z 0237. Alkali glass with an adhesive sheet was pressed for about 20 minutes in an autoclave (50 ° C, 5 atmospheres), and the sample was stored for 1 hour in a constant temperature and humidity condition (23 ° C, 50% relative humidity). Using an analyzer, manufactured by Stable Micro Systems Co., Ltd., the peeling force is measured while the adhesive sheet is peeled from the alkali glass at a peel rate of 300 mm / min and a peel angle of 180 degrees.

In addition, PET adhesion strength is measured in the same manner in addition to using a glass attached to PET using a double-sided tape on the alkali glass as an adhesive. The results are shown in Table 3 below.

Test Example 3 Evaluation of Stress Relaxation Ratio (S / R Ratio)

Pressure-sensitive adhesive sheet prepared in Examples or Comparative Examples

Meter: Rheometer MCR-302, PP25 (25mmΦ)

Measuring condition: Strain 25%, Axial force 1N

Thickness 500㎛ (5 sheets of 100㎛ overlap)

Temp: 70 ℃ (stabilization 10min)

When measuring after stabilization, the 70 ℃ elastic modulus of 1Sec and the elastic modulus after 300Sec are confirmed

70 ℃ elastic modulus of S / R Ratio = 300Sec / 70 ℃ elastic modulus of 1Sec

25mmФ (PP25), Strain 25%, Frequency 1Hz, Axial force 1N,

Temperature 70 ℃ (temperature rise 70 ℃ after stabilization, stabilization 5min), measuring thickness 500㎛

Ratio = G 'at 300 seconds / G' at 0.1 seconds

S / R ratio after primary ultraviolet crosslinking was A, and S / R ratio after secondary ultraviolet crosslinking was B. The results are shown in Table 3 below.

Test Example 4 Step Filling

One side release PET of the adhesive film produced by the above-mentioned method was peeled off, it bonded to the polyethylene terephthalate film (PET100) of thickness 100micrometer, and the adhesive film which PET100 base material was bonded to one side was produced. The test piece was made into what cut | disconnected this to 50 mm length and 40 mm width. Next, the 50-micrometer-thick polyethylene terephthalate film (PET50) was cut out so that it might become a frame of 40 mm in length, 30 mm in width, and 5 mm in width. A mold having a thickness of 50 µm made of cut PET50 was placed on the remaining PET 100 on the peeled PET100 and bonded to another PET100 (PET100 / adhesive / PET50 / PET100 configuration). This was autoclaved for 20 minutes in a 50 degreeC atmosphere by the pressure of 0.5 Mpa, and 3J was irradiated with the metal halide lamp, and the sample was produced. Then, it left to stand for 24 hours in the atmosphere of temperature 80 degreeC, visually observed the inner part of the 50 micrometer-thick frame, and evaluated the filling property with respect to the 50 micrometer-thick step as follows. The evaluation results are shown in Table 3 below.

○: no mixing of air bubbles

△: there is some bubble

×: There are many bubbles

Test Example 5. Durability (heat resistance, heat resistance)

Peeling the release film of one side of the adhesive sheet prepared in Example or Comparative Example and corona-treated and bonded to 40um COP film and pressure-sensitive adhesive side cut to 90mm × 170mm size and peeled off the release film After that, a glass substrate (110 mm x 190 mm x 0.7 mm) was attached to the specimen. At this time, the applied pressure was 5kg / ㎠ and the clean room work so as not to generate bubbles or foreign matter. The heat resistance characteristics were observed whether bubbles or peeling occurred after leaving for 500 hours at a temperature of 100 ℃, the moisture resistance heat resistance was observed whether bubbles or peeling after leaving for 500 hours under the conditions of 85 ℃ temperature and 85% RH Was observed.

<Evaluation Criteria>

Ⓞ: No bubbles or peeling.

○: bubble or peeling <5 pieces

△: 5 ≤ air bubbles or exfoliation <10

×: 10 ≤ air bubbles or peeling

Physical properties measured for the composition are summarized in Table 3 below.

division	Adhesion after 2nd UV curing (N / 25㎜)		S / R Ratio		Step filling	durability
	Glass	PET	Stress relaxation ratio after primary UV curing	Stress relaxation ratio after 2nd UV curing		100 ℃	85 ℃, 85% RH
Example 1	40	25	0.04	0.38	○	Ⓞ	Ⓞ
Example 2	35	22	0.03	0.37	○	Ⓞ	Ⓞ
Example 3	34	28	0.04	0.36	○	Ⓞ	Ⓞ
Example 4	38	20	0.05	0.38	△	○	Ⓞ
Example 5	36	24	0.02	0.31	○	Ⓞ	Ⓞ
Example 6	36	24	0.05	0.4	○	Ⓞ	Ⓞ
Comparative Example 1	34	23	0.20	0.20	X	X	○
Comparative Example 2	38	22	0.00	0.30	○	X	○
Comparative Example 3	35	21	0.05	0.08	△	X	X
Comparative Example 4	19	14	0.05	0.65	△	X	X

The stress relaxation ratio after the first ultraviolet crosslinking at 70 ° C. of the present invention is 0.02 to 0.10, and the stress relaxation ratio after the second ultraviolet crosslinking at the same temperature as the temperature of the first ultraviolet crosslinking is 0.3 to 0.6. In the case of the optically transparent adhesive sheet of Examples 1 to 5 showed very excellent durability, having excellent durability means that it has excellent adhesion, the adhesion is improved, it was confirmed that the effect of the end buried and step resilience also excellent. .

In the case of the optically transparent adhesive sheets of Examples 1 to 5 showed very excellent durability, adhesion was improved, it was confirmed that the step filling effect is also excellent.

On the other hand, at 70 ° C of the present invention, the stress relaxation ratio after the first ultraviolet crosslinking is 0.02 to 0.10, and the stress relaxation ratio after the second ultraviolet crosslinking at the same temperature as the temperature of the first ultraviolet crosslinking is 0.3 or more. In the case of Comparative Examples 1 to 4 that can not do the poor durability, in the case of Comparative Examples 1 and 2 was also poor filling step.

In the film of the present invention, the stress relaxation ratio after primary UV crosslinking at 70 ° C. is 0.02 to 0.10, thereby providing excellent end embedding and step breakability, and the stress relaxation ratio after secondary UV crosslinking at 70 ° C. is 0.3. Designed to 0.6 to minimize the lifting phenomenon from the surface of the adherend, it is possible to provide an energy-curable inorganic adhesive film excellent in step fillability and durability.

Claims (10)

1. An optically transparent adhesive sheet comprising a (meth) acrylate syrup which is a resin syrup prepared by partially polymerizing a (meth) acrylate monomer and a photoinitiator,

   The film has a stress relaxation ratio of 0.02 to 0.10 after the first ultraviolet crosslinking at 70 ° C., and a stress relaxation ratio of 0.3 to 0.6 after the second ultraviolet crosslinking at the same temperature as the temperature of the first ultraviolet crosslinking. Optically transparent adhesive sheet made.
2. The method according to claim 1,

   The photoinitiator is an optically transparent adhesive sheet of at least two selected from the group consisting of a benzophenone initiator, a benzoin initiator, a hydroxyketone initiator, an amino ketone initiator and a phosphine oxide initiator.
3. The method according to claim 1,

   (Meth) acrylate syrup, which is a resin syrup prepared by partially polymerizing a (meth) acrylate monomer, includes an acrylate monomer comprising a hydroxy group; Monophoto (meth) acrylate monomers; And comprising a photoinitiator, optically transparent adhesive sheet.
4. The method according to claim 3,

   The acrylate monomer containing the hydroxy group is contained 5 to 20% by weight based on the total weight of the resin syrup prepared by partially polymerizing the (meth) acrylate monomer, optically transparent adhesive sheet.
5. The method according to claim 1,

   The (meth) acrylate monomer is monofunctional, optically transparent adhesive sheet.
6. The method according to claim 1,

   The photoinitiator is an optically transparent adhesive sheet containing 0.1 to 5 parts by weight when the (meth) acrylate syrup, which is a resin syrup prepared by partially polymerizing the (meth) acrylate monomer, to 100 parts by weight.
7. In claim 3,

   The photoinitiator is an optically transparent adhesive sheet containing 0.1 to 5 parts by weight when the total amount of the acrylate monomer and the monofunctional (meth) acrylate monomer including the hydroxyl group is 100 parts by weight.
8. A composition comprising a (meth) acrylate resin syrup, a photoinitiator and a (meth) acrylate monomer, which is a resin syrup prepared by partially polymerizing a (meth) acrylate monomer, wherein the composition comprises the optically transparent adhesive sheet of claim 1 Composition for preparation.
9. A flat panel display comprising the optically transparent adhesive sheet of claim 1.
10. The method according to claim 9,

    The flat panel display device of claim 1, wherein the flat panel display device is a flexible display device.