JP2023017753A - Adhesive film, optical member comprising the same and optical display device comprising the same - Google Patents

Abstract

To provide an adhesive film that improves the utilization efficiency of light entering it.SOLUTION: An adhesive film comprises a cured adhesive composition containing a polymerized monomer mixture containing at least one aromatic group-containing methacrylate. The adhesive film has a refractive index of 1.55 or more, an initial degradation rate of 10%-20%, and a gel fraction of 50%-70%. There are also provided an optical member comprising the same, and an optical display device comprising the same.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an adhesive film, an optical member containing the same, and an optical display device containing the same.

An organic light-emitting device includes a laminated structure of several thin films, and more than 80% of the light generated in the light-emitting layer is reflected or absorbed inside or at the interface of the organic light-emitting device and disappears without being emitted to the front surface. , can reduce light efficiency. Due to the low light efficiency, the power consumption must be increased in order to achieve the desired brightness, and the life of the organic light emitting device is also reduced. Therefore, research for improving light efficiency has become an important subject.

In this regard, studies are being conducted to improve light efficiency by stacking a patterned optical device on top of the organic light emitting device. As one form of such research, referring to FIG. 3, a structure in which an inorganic layer 200, a low refractive index organic layer 300, and a high refractive index organic layer 400 are sequentially formed on the upper surface of an organic light emitting device 100 is proposed. ing. The inorganic layer 200 is made of inorganic particles such as silicon nitride, silicon oxynitride, silicon oxide, titanium oxide, and aluminum oxide, and exhibits a high refractive index. Since the high refractive index organic layer 400 is in contact with the inorganic layer 200, visibility and light efficiency are not improved unless it adheres well to the inorganic layer 200 and has a high refractive index, such as a refractive index of 1.55 or higher. .

In general, methods of including inorganic particles can be considered to increase the refractive index. However, when inorganic particles are included, it becomes difficult to control the compatibility with the organic (meth)acrylate binder. The use of particles leads to increased material costs.

Korean Patent No. 10-2007-0055363

SUMMARY OF THE INVENTION An object of the present invention is to provide an adhesive film that enhances the light efficiency of incident light.

Another object of the present invention is to provide an adhesive film with significantly improved adhesion to patterned optical elements.

Still another object of the present invention is to provide a pressure-sensitive adhesive film having high peel strength and excellent heat resistance reliability and wet heat resistance reliability.

Still another object of the present invention is to provide an adhesive film which does not have the problem of matching compatibility with inorganic particles and the problem of an increase in the production cost of the adhesive film.

The pressure-sensitive adhesive film of the present invention is obtained by curing a pressure-sensitive adhesive composition containing a polymer of a monomer mixture containing one or more aromatic group-containing (meth)acrylates, and the pressure-sensitive adhesive film has a refractive index of 1.55. As described above, the initial decomposition rate is 10% to 20% and the gel fraction is 50% to 70%.

Another aspect of the present invention is an optical member.

An optical member contains the adhesive film of this invention.

Another aspect of the invention is an optical display device.

An optical display device includes the optical film of the present invention.

4 is a graph for explaining the calculation of the initial decomposition rate; 1 is a cross-sectional schematic diagram showing an optical display device according to an embodiment of the present invention; FIG. 1 is an exemplary cross-sectional schematic diagram of a structure for enhancing the light efficiency of an organic light emitting device; FIG.

The present invention will be described in detail with reference to the accompanying drawings and examples so that those skilled in the art can easily carry it out. This invention may be embodied in many different forms and should not be limited to the embodiments set forth herein. In the drawings, parts unrelated to the description are omitted in order to clearly describe the present invention, and the same or similar components are given the same reference numerals throughout the specification.

In this specification, "upper" and "lower" are defined based on the drawings, and "upper" may be changed to "lower" and "lower" to "upper" depending on the viewpoint. The term "on" or "on" may include not only right above but also other structures interposed therebetween. On the other hand, what is referred to as "directly on", "directly on" or "directly formed" or "directly adjacent to formed" means that there is no intervening other structure.

As used herein, "(meth)acryl" means acryl and/or methacryl.

As used herein, the term "refractive index" is a value measured with light in the visible light region, specifically with a wavelength of 633 nm.

As used herein, "adhesive strength" is a value measured based on the standard of JIS C2107:2011 with respect to a glass plate (non-alkali glass plate) as an adherend.

In this specification, the numerical range “X to Y” means “X or more and Y or less” (X≦,≦Y).

The present invention relates to an adhesive film that is laminated to the top surface of a patterned optical element. An inorganic layer is laminated on the upper surface of the optical element, and a pattern having a predetermined shape is formed on at least a part of the inorganic layer. Patterned optical elements are described in greater detail below.

The pressure-sensitive adhesive film of the present invention has the effect of increasing the light extraction efficiency of light emitted from the patterned optical element, so that high brightness can be realized with relatively low power consumption, thereby emitting light. The life of the device can be extended.

As will be described below, the above effects can be provided by setting the refractive index of the adhesive film to 1.55 or higher. The pressure-sensitive adhesive film of the present invention contains inorganic particles having a high refractive index (eg, refractive index of 1.55 or more, specifically 1.55 to 2.0), such as zirconia (ZrO ₂ ) and titania (TiO ₂ ). does not include Therefore, the adhesive film of the present invention has a problem that compatibility between inorganic particles and an organic polymer must be matched, and the introduction of inorganic particles increases the storage elastic modulus (G') of the adhesive film and lowers the adhesive strength. problem, and the problem of increased production cost of the adhesive film due to the use of inorganic particles can be eliminated.

The pressure-sensitive adhesive film of the present invention has a significantly superior degree of adhesion to patterned optical elements. Here, "remarkably excellent degree of adhesion" means that the space between the patterned surface of the optical element and the adhesive film is minimized, there are no air bubbles, and the patterned surface is completely filled. means that the pressure-sensitive adhesive film and the patterned surface are completely adhered to each other. As a result, the pressure-sensitive adhesive film of the present invention prevents detachment and/or separation between the patterned optical element and another optical element laminated on the upper surface of the optical element, such as a polarizing plate, thereby providing a display. The reliability of the device can be improved. In addition, the pressure-sensitive adhesive film of the present invention minimizes the area between the patterned optical element and the pressure-sensitive adhesive film that do not adhere to each other, thereby eliminating problems such as low light efficiency.

The adhesive film of the present invention is excellent in heat resistance reliability and wet heat resistance reliability. Therefore, the pressure-sensitive adhesive film of the present invention prevents detachment and/or separation between the patterned optical element and another optical element laminated on the top surface of the optical element, such as a polarizing plate, thereby preventing the display device from reliability can be improved.

As will be explained below, all the effects of the present invention described above cannot be achieved by unconditionally increasing the peel strength of the adhesive film. It can be achieved by adjusting the initial decomposition rate to 10% to 20%. Gel fraction and initial degradation rate are discussed in detail below.

Hereinafter, an adhesive film according to an embodiment of the present invention will be described.

The adhesive film of the present invention has a refractive index of 1.55 or more. If the refractive index is within this range, it is possible to provide the effect of increasing the light extraction efficiency of the light emitted from the light emitting element when laminated on the light emitting surface of the patterned optical element. For example, the adhesive film has a refractive index of 1.55 to 1.65, specifically 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.61. 62, 1.63, 1.64, 1.65.

The adhesive film of the present invention has an initial decomposition rate of 10% to 20% and a gel fraction of 50% to 70%. Within this range, the degree of adhesion to the patterned optical element is excellent, providing excellent reliability, preventing a decrease in light efficiency due to poor adhesion, and improving heat resistance and moist heat resistance reliability. can be excellent. For example, the initial decomposition rate is preferably 13% to 18%, specifically 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, the gel fraction is preferably 50% to 65%, specifically 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60% %, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%.

Initial decomposition rates are calculated from thermogravimetric analysis (TGA). Specifically, a method for obtaining an initial decomposition rate will be described with reference to FIG.

Referring to FIG. 1, when DSC is measured for a cling film test piece with a predetermined content, the X-axis is temperature (unit: ° C.), and the Y-axis is the percentage of the weight at a specific temperature relative to the initial weight of the test piece. (Unit: %) graph (solid line graph in FIG. 1) can be obtained. The measurement conditions for DSC are as follows:
1) Temperature range: Increase temperature from 25°C to 700°C 2) Temperature increase rate: 10°C/min 3) Under nitrogen atmosphere.

Temperature (T) (X axis, unit: ° C.) and d (W) / d (T) (Y axis, unit: %) is obtained (a dashed-dotted line graph in FIG. 1). Obtain the first inflection point (A in FIG. 1), the onset temperature including the first inflection point (B in FIG. 1) and the end temperature (C in FIG. 1) in the obtained differential curve. After that, the initial decomposition rate is calculated through the ratio of the area between the interval from the start temperature to the end temperature and the reference line to the total area between the differential curve and the reference line. Here, the "reference line" is a line where d(W)/d(T) is zero. The initial decomposition rate can be obtained using an analysis program (TRIOS, Discovery TA), but is not limited to this.

The inventors have determined that the initial decomposition rate is another factor that increases the degree of adhesion to patterned optical elements. Although the specific reason for this is unknown, the initial decomposition rate is determined by the low-molecular-weight component among the multiple components in the adhesive film, such as the low-molecular-weight copolymer or oligomer in the copolymer. be done. The low molecular weight copolymers or oligomers, or cured products thereof, in the adhesive film are relatively flexible compared to the high molecular weight copolymers or oligomers, and thus better adhere to the patterned surface of the optical element. It is foreseeable that it could be attached, but is not so limited.

The gel fraction is calculated by Equation 1 below. In general, the gel fraction evaluates the degree of aging of the adhesive film when producing the adhesive film from the adhesive composition. However, the inventors have determined that gel fraction is one factor that enhances the degree of adhesion to patterned optical elements.

In the above formula 1,
_WA is the weight of the wire mesh (unit: g),
_WB is the total weight (unit: g) of the wire mesh and adhesive film measured after preparing a test piece by putting 0.5 g of the adhesive film in the wire mesh,
For _WC , the test piece was placed in a 100 cc sample bottle, 50 cc of toluene was added, and the test piece was completely immersed in toluene. It is the weight (unit: g) measured after drying at °C for 12 hours.

In one specific example, the mesh size of the wire mesh may be 100 mesh.

The adhesive film may have an adhesive strength of 800 gf/inch or more to a glass plate. Adhesive strength in this range can reliably adhere to the patterned optical element. For example, the adhesive film has an adhesive strength to a glass plate of 800 gf/inch to 2000 gf/inch, specifically 800 gf/inch, 850 gf/inch, 900 gf/inch, 950 gf/inch, 1000 gf/inch, 1050 gf/inch, 1100 gf /inch, 1150gf/inch, 1200gf/inch, 1250gf/inch, 1300gf/inch, 1350gf/inch, 1400gf/inch, 1450gf/inch, 1500gf/inch, 1550gf/inch, 1600gf/inch, 1650gf/inch, 1700gf/inch , 1750 gf/inch, 1800 gf/inch, 1850 gf/inch, 1900 gf/inch, 1950 gf/inch, 2000 gf/inch. Note that 1 gf/inch= ^0.386 kg/s2.

The adhesive film of the present invention is optically transparent and can be used for optical display devices. In one embodiment, the adhesive film can have a light transmission of 90% or more, such as 90% to 100%.

The adhesive film of the present invention may have a haze of 1% or less, eg 0.001% to 0.5%. If the haze is within this range, it can be applied to an optical display device. Haze can be easily achieved since the adhesive film does not contain the inorganic particles mentioned above, so there is no problem of compatibility control between the organic copolymer and the inorganic particles. The haze can be measured according to JIS K7136:2000.

The adhesive film may typically have a thickness of 50 μm or less, eg from 5 μm to 30 μm. If the thickness is within this range, it can be used in an optical display device.

The adhesive film is a pressure sensitive adhesive (PSA) film obtained by curing the adhesive composition described below. For example, an adhesive film can be produced by applying an adhesive composition to one surface of a release film in a predetermined thickness, drying it, and aging it. Drying can be performed at 100° C. to 150° C. for 30 seconds to 5 minutes, but is not limited thereto. Aging can be performed by leaving at 25° C. to 40° C. for 1 to 5 days. After aging, a further step of standing at a lower aging temperature, eg, 20° C. to 30° C., for about 5 hours to about 15 hours can be performed.

The adhesive composition will be described below.

The pressure-sensitive adhesive composition of the present invention contains a polymer of a monomer mixture containing one or more aromatic group-containing (meth)acrylic monomers and a curing agent. Here, the "aromatic group" can mean an aryl group having 6 to 20 carbon atoms. An aryl group can include a single ring, multiple rings (fused), or a ring assembly of linked single rings (eg, a biphenyl group). Here, the "polymer" can include one or more of copolymers, oligomers, and prepolymers.

A polymer of a monomer mixture containing one or more aromatic group-containing (meth)acrylic monomers can help achieve the refractive index and initial decomposition rate according to the present invention.

The monomer mixture may contain one or more aromatic group-containing (meth)acrylic monomers and a (meth)acrylic monomer having a hydroxyl group.

The aromatic group-containing (meth)acrylic monomer can increase the refractive index of the adhesive film. In one specific example, the aromatic group-containing (meth)acrylic monomer has a homopolymer refractive index of 1.5 or more, specifically 1.5, 1.55, 1.6, 1.65. , 1.7, such as 1.55 to 1.7. Within the above refractive index range, the refractive index of the present invention can be easily obtained.

The aromatic group-containing (meth)acrylic monomer may have a homopolymer glass transition temperature of 0°C to 40°C. Within this range, the pressure-sensitive adhesive film does not become too hard, so that it can adhere well to the patterned optical element. For example, the glass transition temperature can be from 0°C to 35°C, specifically 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C. As used herein, the "glass transition temperature of a homopolymer" can be determined by referring to product catalogs or measured by a conventional method known to those skilled in the art.

The pressure-sensitive adhesive film of the present invention contains a large amount of the aromatic group-containing (meth)acrylic monomer having the glass transition temperature of the above homopolymer as described below to increase the refractive index while increasing the initial decomposition rate. In order to achieve the above, the adhesive film has a glass transition temperature of -5 ° C. to 20 ° C., specifically, -5 ° C., -4 ° C., -3 ° C., -2 ° C., -1 ° C., 0 ° C. , 1°C, 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C ℃, 18 ℃, 19 ℃, 20 ℃.

As the aromatic group-containing (meth)acrylic monomer, a monomer having one aromatic group can be used, but a monomer having two or more aromatic groups is preferably used. A monomer having two or more aromatic groups can easily increase the refractive index of the pressure-sensitive adhesive film compared to a monomer having one aromatic group even when used in the same amount. In one embodiment, the aromatic group-containing (meth)acrylic monomer can have 2 to 5 aromatic groups.

In one embodiment, the aromatic group-containing (meth)acrylic monomer can have a structure represented by Formula 1 below:

In the above chemical formula 1, * is a linking site,
X is a single bond, an alkylene group having 1 to 5 carbon atoms, or an oxygen atom (O).

The aromatic group-containing (meth)acrylic monomer may be a monofunctional (meth)acrylate having one (meth)acryloyloxy group. Accordingly, it is possible to minimize the problem of poor adhesion to the patterned optical element due to hardening of the adhesive film due to excessive polymerization of the monomer during the production of the polymer, which is defined in the present invention. The initial degradation rate and cohesion to be achieved can be easily reached.

In one embodiment, the aromatic group-containing (meth)acrylic monomer may include a compound represented by Formula 2 below:

In the above chemical formula 2,
X is a single bond, an alkylene group having 1 to 5 carbon atoms, or an oxygen atom (O),
Y is hydrogen or a methyl group;
R ₁ is an alkyl group having 1 to 10 carbon atoms, a halogen atom, or an aryl group having 6 to 20 carbon atoms,
n is an integer from 0 to 5,
R ₂ is an alkylene group having 1 to 10 carbon atoms or a mono- or polyalkyleneoxy group having 1 to 30 carbon atoms in total.

In one specific example, in Formula 2 above, the mono- or polyalkyleneoxy group having 1 to 30 carbon atoms as a whole is -*(-O-R ₃ -) _n -* (* is a linking moiety, R ₃ is an alkylene group having 1 to 3 carbon atoms, and n is an integer of 1 to 10).

For example, the (meth)acrylic monomer having an aromatic group includes o-phenylbenzyl acrylate, m-phenylbenzyl acrylate, or p-phenylbenzyl acrylate, phenylbenzyl (meth)acrylate; phenoxybenzyl (meth) acrylates; monoethoxylated phenylphenoxy (meth)acrylates; polyethoxylated phenylphenoxy (meth)acrylates including diethoxylated phenylphenoxy (meth)acrylates; and the like.

In one embodiment, the monomer mixture can contain at least one (meth)acrylic monomer having an aromatic group.

In another specific example, since each (meth)acrylic monomer having an aromatic group has a different homopolymer refractive index, glass transition temperature, etc., a (meth)acrylic monomer having an aromatic group is used. By including two or more kinds in a mixed manner, the effect of the present invention can be more easily realized.

For example, the (meth)acrylic monomer having an aromatic group has a first aromatic group in which X in Chemical Formula 2 is a single bond or an alkylene group having 1 to 5 carbon atoms (meth ) an acrylic monomer and a (meth)acrylic monomer having a second aromatic group in which X in Formula 2 above is oxygen (O). By using such a mixture, the effects of increasing adhesive strength and improving flexibility can be obtained.

The (meth)acrylic monomer having the first aromatic group can include, but is not limited to, phenylbenzyl acrylate. The (meth)acrylic monomer having a second aromatic group can include, but is not limited to, phenoxybenzyl (meth)acrylate.

The (meth)acrylic monomer having the first aromatic group is 70% by mass to 90% by mass, specifically 70% by mass, 71% by mass, based on the total mass of the monomer mixture. 72% by mass, 73% by mass, 74% by mass, 75% by mass, 76% by mass, 77% by mass, 78% by mass, 79% by mass, 80% by mass, 81% by mass, 82% by mass, 83% by mass, 84% by mass %, 85 wt %, 86 wt %, 87 wt %, 88 wt %, 89 wt %, 90 wt %, for example 70 wt % to 80 wt %. The (meth)acrylic monomer having a second aromatic group is 1% by mass to 15% by mass, specifically 1% by mass, 2% by mass, based on the total mass of the monomer mixture. 3% by mass, 4% by mass, 5% by mass, 6% by mass, 7% by mass, 8% by mass, 9% by mass, 10% by mass, 11% by mass, 12% by mass, 13% by mass, 14% by mass, 15% by mass %, for example 5% to 15% by weight.

Another example of a (meth)acrylic monomer having an aromatic group is a third aromatic group in which R ₂ in Chemical Formula 2 is an alkylene group having 1 to 10 carbon atoms or an oxygen atom. and a (meth)acrylic monomer having a fourth aromatic group in which R ₂ in Chemical Formula 2 is a (poly)alkyleneoxy group having 1 to 30 carbon atoms It can contain mixtures. Since the (meth)acrylic monomer having the fourth aromatic group provides flexibility, the adhesion of the adhesive film to the patterned optical element can be enhanced.

The (meth)acrylic monomer having a third aromatic group can include, but is not limited to, one or more of phenylbenzyl acrylate and phenoxybenzyl (meth)acrylate. The (meth)acrylic monomer having a fourth aromatic group can include one or more of monoethoxylated phenylphenoxy (meth)acrylate and poly(ethoxylated)phenylphenoxy (meth)acrylate. , but not limited to these.

The (meth)acrylic monomer having a third aromatic group is 70% by mass to 90% by mass, specifically 70% by mass, 71% by mass, based on the total mass of the monomer mixture. 72% by mass, 73% by mass, 74% by mass, 75% by mass, 76% by mass, 77% by mass, 78% by mass, 79% by mass, 80% by mass, 81% by mass, 82% by mass, 83% by mass, 84% by mass %, 85 mass %, 86 mass %, 87 mass %, 88 mass %, 89 mass %, 90 mass %, for example, 70 mass % to 80 mass %. The (meth)acrylic monomer having a fourth aromatic group is 1% by mass to 15% by mass, specifically 1% by mass, 2% by mass, based on the total mass of the monomer mixture. 3% by mass, 4% by mass, 5% by mass, 6% by mass, 7% by mass, 8% by mass, 9% by mass, 10% by mass, 11% by mass, 12% by mass, 13% by mass, 14% by mass, 15% by mass %, for example 5% to 15% by weight.

One or more aromatic group-containing (meth)acrylic monomers are 75% by mass to 95% by mass, specifically 75% by mass, 76% by mass, based on the total mass of the monomer mixture, 77% by mass, 78% by mass, 79% by mass, 80% by mass, 81% by mass, 82% by mass, 83% by mass, 84% by mass, 85% by mass, 86% by mass, 87% by mass, 88% by mass, 89% by mass %, 90% by weight, 91% by weight, 92% by weight, 93% by weight, 94% by weight, 95% by weight, for example 75% to 90% by weight, 75% to 85% by weight. If the content is within the above range, the refractive index of the adhesive film can be ensured, and the problem of low adhesive strength of the adhesive film can be eliminated.

A (meth)acrylic monomer having a hydroxyl group is a (meth)acrylic monomer having an alkyl group having 1 to 20 carbon atoms containing one or more hydroxyl groups in the ester moiety, and one or more in the ester moiety. It may contain one or more (meth)acrylic monomers having a cycloalkyl group having 3 to 20 carbon atoms containing a hydroxyl group.

A (meth)acrylic monomer having a hydroxyl group may have a lower glass transition temperature than a (meth)acrylic monomer containing an aromatic group. This makes it possible to increase the adhesion of the adhesive film so that it adheres well to the patterned optical element, and also increases the adhesion. For example, a (meth)acrylic monomer having a hydroxyl group has a homopolymer glass transition temperature of -10°C or less, specifically -50°C, -45°C, -40°C, -35°C, -30°C. °C, -25°C, -20°C, -15°C, -10°C, for example -50°C to -10°C.

In one specific example, as the (meth)acrylic monomer having a hydroxyl group, a (meth)acrylate having an alkyl group of 1 to 20 carbon atoms containing one or more hydroxyl groups in the ester moiety can be used. Specifically, (meth)acrylic monomers having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl ( It may include one or more of meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 1-chloro-2-hydroxypropyl (meth)acrylate. A (meth)acrylic monomer having a hydroxyl group can be used alone or in combination of two or more.

The (meth)acrylic monomer having a hydroxyl group is 5% by mass to 25% by mass, specifically, 5% by mass, 6% by mass, 7% by mass, 8% by mass, based on the total mass of the monomer mixture. % by mass, 9% by mass, 10% by mass, 11% by mass, 12% by mass, 13% by mass, 14% by mass, 15% by mass, 16% by mass, 17% by mass, 18% by mass, 19% by mass, 20% by mass , 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, for example, 10 wt% to 25 wt%, 15 wt% to 25 wt%. If the content is within the above range, the effect of the present invention can be easily achieved. The present invention uses a (meth)acrylic monomer with a relatively high content of hydroxyl groups compared to the prior art to provide an adhesive film that adheres well to patterned optical elements. .

The total content of the (meth)acrylic monomer having an aromatic group and the (meth)acrylic monomer having a hydroxyl group is 95% by mass or more, for example 98% by mass to 100% by mass, in the monomer mixture. %, preferably 100% by mass.

The monomer mixture may contain a (meth)acrylic acid ester having a linear or branched C 1-10 alkyl group at the ester moiety. (Meth)acrylic acid esters having a linear or branched C 1-10 alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, ) acrylate, iso-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, iso-octyl (meth) acrylate , nonyl (meth)acrylate, decyl (meth)acrylate, and dodecyl (meth)acrylate.

Since the polymer has a high polydispersity index (PDI), the molecular weight distribution of oligomers, copolymers, etc. contained in the polymer is wide. The inventors have determined that such a high polydispersity index can help achieve the initial degradation rate and gel fraction in the present invention. In one embodiment, the polymer has a polydispersity index (PDI) of 5 or greater, specifically about 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, It can be 9, 9.5, 10, such as 5-10.

The polymer has a weight average molecular weight of 100,000 g/mol to 5,000,000 g/mol. 4 million, 4.5 million, 5 million g/mol, such as 100,000 g/mol to 3 million g/mol, 100,000 g/mol to 2 million g/mol. If the weight average molecular weight is within the above range, the adhesive strength and durability reliability of the adhesive film can be ensured.

The polydispersity index can be calculated (Mw/Mn) by measuring the weight average molecular weight (Mw) and number average molecular weight (Mn) using gel permeation chromatography (GPC).

The polymer can be prepared by adding an initiator to the monomer mixture and then polymerizing the mixture. The initiator can include one or more of photoinitiators and thermal initiators. As the photopolymerization initiator and the thermal polymerization initiator, usual ones known to those skilled in the art can be used. For example, initiators can be conventional, including azo polymerization initiators; and/or peroxides such as benzoyl peroxide or acetyl peroxide, and the like.

The initiator is 0.01 parts by mass to 0.5 parts by mass, preferably 0.01 parts by mass to 0.1 parts by mass, more preferably 0.03 parts by mass to 100 parts by mass of the monomer mixture. It may be included at a content of 0.08 parts by mass. If the content is within the above range, the polymer can be easily obtained.

Polymerization can include conventional polymerization methods known to those skilled in the art, such as suspension polymerization, emulsion polymerization, solution polymerization, and the like. The polymerization temperature can be 60° C. to 80° C., and the polymerization time can be 4 hours to 8 hours. If it is such a range, a polymer can be obtained easily.

The curing agent cures the polymer to form a matrix of the adhesive film, thereby increasing adhesive strength. The curing agent can include one or more of isocyanate-based curing agents, epoxy-based curing agents, metal chelate-based curing agents, and aziridine-based curing agents. Preferably, an isocyanate-based curing agent can be used as the curing agent.

Isocyanate-based curing agents include hexamethylene diisocyanate (HDI), 2,4-toluene diisocyanate, toluene diisocyanate (TDI) including 2,6-toluene diisocyanate, 4,4′-methylene diphenyl diisocyanate (MDI), 1,3 -xylylene diisocyanate, xylylene diisocyanate (XDI) including 1,4-xylylene diisocyanate, hydrogenated toluene diisocyanate, isophorone diisocyanate, 1,3-bisisocyanatomethylcyclohexane, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate , 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, trimethylolpropane toluene diisocyanate adducts including trimer adducts of trimethylolpropane/toluene diisocyanate, xylylene of trimethylolpropane Adducts of the above isocyanate-based curing agents such as isocyanate adducts, triphenylmethane triisocyanate, and methylenebistriisocyanate can be included.

A curing agent such as an isocyanate curing agent is used in an amount of 0.01 part by mass to 1 part by mass, specifically 0.01 part by mass, 0.05 part by mass, or 0.1 part by mass with respect to 100 parts by mass of the polymer. parts by mass, 0.15 parts by mass, 0.2 parts by mass, 0.25 parts by mass, 0.3 parts by mass, 0.35 parts by mass, 0.4 parts by mass, 0.45 parts by mass, 0.5 parts by mass , 0.55 parts by mass, 0.6 parts by mass, 0.65 parts by mass, 0.7 parts by mass, 0.75 parts by mass, 0.8 parts by mass, 0.85 parts by mass, 0.9 parts by mass, 0 .95 parts by weight, 1 part by weight, for example 0.01 to 0.5 parts by weight. If the content is within the above range, it is possible to achieve the effect of simultaneously satisfying durability and adhesive strength.

The adhesive composition may further contain a silane coupling agent.

A silane coupling agent can increase the adhesive strength of the adhesive film and improve reliability.

The silane coupling agent includes at least one of an acetylacetonate-based silane coupling agent having an acetylacetonate group, an acetoacetate-based silane coupling agent having an acetoacetate group, and an epoxy-based silane coupling agent having an epoxy group. be able to. For example, epoxy-based silane coupling agents can include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like. but not limited to these. Acetylacetonate-based silane coupling agents or acetoacetate-based silane coupling agents can include 3-(trimethoxysilyl)propylacetoacetate, acetylacetonatetrimethoxysilane, acetylacetonatetriethoxysilane, etc. It is not limited to these.

The silane coupling agent is 0.1 parts by mass to 1 part by mass with respect to 100 parts by mass of the polymer, specifically 0.1 parts by mass, 0.15 parts by mass, 0.2 parts by mass, 0 .25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, 0.45 parts by weight, 0.5 parts by weight, 0.55 parts by weight, 0.6 parts by weight, 0.65 parts by weight parts by mass, 0.7 parts by mass, 0.75 parts by mass, 0.8 parts by mass, 0.85 parts by mass, 0.9 parts by mass, 0.95 parts by mass, 1 part by mass, for example, from 0.1 parts by mass to It may be contained at a content of 0.5 parts by mass. When the content is within the above range, the adhesive strength of the adhesive film can be further improved.

The pressure-sensitive adhesive composition may further contain curing catalysts, additives, and the like.

Curing catalysts include, for example, metal catalysts such as tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonate) iron, tris(hexane-2,4-dionate) iron, tris(heptane-2,4- iron-based catalysts, such as ironate). The curing catalyst may be included in an amount of 0.001 to 0.01 parts by weight, specifically 0.005 to 0.01 parts by weight, based on 100 parts by weight of the polymer. If the content is within the above range, the effect of the present invention can be more easily realized.

Additives can include conventional additives known to those skilled in the art, such as antistatic agents, particles, fillers, antioxidants, heat stabilizers, UV absorbers, surfactants, and the like. The additive may be included in an amount of 0.001 to 5 parts by weight, specifically 0.01 to 1 part by weight, based on 100 parts by weight of the polymer. If the content is within the above range, the effect of the additive can be obtained without affecting the physical properties of the pressure-sensitive adhesive layer.

The adhesive composition may be solventless or may further contain a solvent. When the pressure-sensitive adhesive composition contains a solvent, the pressure-sensitive adhesive film can be made thinner to improve coatability. Usual solvents known to those skilled in the art can be used as the solvent. For example, the solvent can include one or more of methyl ethyl ketone, ethyl acetate, and toluene.

The optical member of the invention includes the adhesive film of the invention.

An optical member according to an embodiment of the present invention will be described below.

The optical member may include a first adhesive film and a polarizing plate laminated on the upper surface of the first adhesive film, and the first adhesive film may include the adhesive film of the present invention.

A polarizing plate may include a polarizer and a protective layer or film laminated on at least one surface of the polarizer. Polarizers, protective layers, and protective films can be of the usual types known to those skilled in the art.

The optical member may further include a second adhesive film between the first adhesive film and the polarizing plate. The second adhesive film has a lower refractive index than the first adhesive film. The second adhesive film can increase the adhesive strength to the first adhesive film and the polarizing plate, thereby enhancing the reliability of the optical member.

An optical display device includes the pressure-sensitive adhesive film or optical member of the present invention. Optical displays can include light emitting device displays including organic light emitting devices, inorganic light emitting devices, organic-inorganic hybrid light emitting devices, and the like.

An optical display device according to an embodiment of the present invention will be described below with reference to FIG.

Referring to FIG. 2, the optical display device includes an organic light emitting device 100, a patterned optical element laminated on the top surface of the organic light emitting device 100, and a high refractive index organic layer 500, wherein the patterned optical element includes an inorganic layer 200 and a low refractive index organic layer 300 that are sequentially stacked from the organic light emitting device 100, and the high refractive index organic layer 500 may include the adhesive film of the present invention. A low refractive index organic layer 300 is disposed on the inorganic layer 200 and can be a protruding pattern having a predetermined cross-sectional shape. Such patterned optical elements can ensure process stability. As shown in FIG. 2, the low-refractive-index organic layer 300 has a plurality of patterns having a predetermined cross section separated from each other. A pattern surface of 100 μm can be provided. The low-refractive-index organic layer 300 may be made of, but not limited to, an acrylic material.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, this is presented as a preferred example of the invention and should not be construed as limiting the invention in any way.

Production Example 1 Production of (Meth)acrylic Polymer 80 parts by mass of ethyl acetate was added to a 1 L reactor in which nitrogen gas was refluxed and a cooling device was provided to facilitate temperature control. A unit containing 70 parts by weight of p-phenylbenzyl acrylate (PBA), 15 parts by weight of phenoxybenzyl acrylate (PoBA), and 15 parts by weight of 4-hydroxybutyl acrylate (4-HBA, homopolymer glass transition temperature: −40° C.) 100 parts by mass of the polymer mixture was added to the reactor. A mixture of ethyl acetate and methyl ethyl ketone was further added to the reactor. After purging the reactor with nitrogen gas for 1 hour to remove oxygen from the monomer mixture, the internal temperature of the reactor was maintained at 70°C. After uniformly stirring the monomer mixture, 0.05 part by mass of azobisisobutyronitrile (AIBN) as an initiator is added and polymerized for 4 hours to obtain a solution containing a (meth)acrylic polymer. Ethyl acetate was added to produce a (meth)acrylic polymer solution having a solid content of 35% by mass.

Production Examples 2 to 7: Production of (meth)acrylic polymer The content of each monomer, the polymerization time and/or the content of the initiator were changed as shown in Table 1 below (unit: parts by mass). A (meth)acrylic polymer solution was produced in the same manner as in Production Example 1, except that In addition, the notation of "-" in Table 1 below means that the corresponding component is not included.

The ingredients used in the examples and comparative examples below are as follows:
(1) Curing agent: hexamethylene diisocyanate curing agent (CK-164, manufactured by NCI)
(2) Silane coupling agent: Acetylacetonetrimethoxysilane (A-50, manufactured by Soken Chemical Co., Ltd.).

Example 1
Based on the solid content, 100 parts by mass of the (meth)acrylic polymer of Production Example 1, 0.4 parts by mass of the curing agent, and 0.25 parts by mass of the silane coupling agent were mixed, and 10 parts by mass of toluene was added. A pressure-sensitive adhesive composition was produced by stirring for 30 minutes.

The produced pressure-sensitive adhesive composition is applied to a first release film (peeling force of the following pressure-sensitive adhesive film to the first release film: 12 gf / inch, PET film, RPK501, manufactured by Toray Industries, Inc.) to a predetermined thickness, It was dried at 120° C. for 2 minutes to form an adhesive film coating (thickness: 20 μm). A second release film (peeling force of the following adhesive film to the second release film: 3 gf / inch, PET film, RPK201, manufactured by Toray Industries, Inc.) is laminated on the coating film for the adhesive film, and constant temperature and humidity conditions ( The first release film-adhesive film ( Thickness: 20 μm)—A pressure-sensitive adhesive sheet was produced in which a second release film was laminated in order.

Examples 2 to 5
The first release film-adhesive film ( Thickness: 20 μm)—A pressure-sensitive adhesive sheet was produced in which a second release film was laminated in order.

Comparative Example 1 and Comparative Example 2
The first release film-adhesive film ( Thickness: 20 μm)—A pressure-sensitive adhesive sheet was produced in which a second release film was laminated in order.

Using the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples, the following physical properties were evaluated, and the results are shown in Table 2 below.

(1) Initial decomposition rate (unit: %): The initial decomposition rate was measured using a thermogravimetric analysis (TGA) device Discovery (first generation) manufactured by TA Instruments. Peel off all the release film from the adhesive sheet to obtain an adhesive film, take 0.1 g of the adhesive film, put it in Discovery (first generation) manufactured by TA Instrument, and heat it from 25 ° C. to 700 ° C. for 10 minutes under a nitrogen atmosphere. The temperature was raised at a rate of temperature rise of ° C./min, and the result of temperature (T) (X axis, unit: ° C.) - weight (W) (Y axis, unit: %) as shown in FIG. 1 was obtained. . By differentiating the obtained results, temperature (T) (X-axis, unit: °C) - d(W)/d(T) (Y-axis, unit: %) was obtained. After searching for the first inflection point in the obtained differential curve and setting the temperature range including the inflection point and including the start temperature and the end temperature, an analysis program (TRIOS, Discovery TA) was used to perform initial decomposition. got the rate.

(2) Gel fraction (unit: %): The release film was completely peeled off from the adhesive sheet to obtain an adhesive film, and 0.5 g of the adhesive film was taken from the adhesive film. The weight (W _A ) was measured in advance against a wire mesh (100 mesh). 0.5 g of the adhesive film was completely wrapped with this wire mesh so that the adhesive film did not leak completely, and the weight (W _B ) of the adhesive film and the wire mesh as a whole was measured again. Next, the adhesive film and the entire wire mesh were placed in a 100 cc sample bottle for gel fraction measurement. Subsequently, 50 cc of toluene was added to the sample bottle so that the adhesive film and the entire wire mesh were completely immersed in toluene. In this state, it was left at 25° C. for one day. Then, after taking out the adhesive film and the entire wire mesh from the sample bottle, they were dried in an oven at 120° C. for 12 hours, and the weight (W _C ) was measured again. The gel fraction was calculated according to Equation 1 below.

(3) Refractive index: An adhesive film was obtained by peeling off the release film from the adhesive sheet. A prism coupler (Metricon, model 2010/M) was used for the adhesive film, and light with a wavelength of 633 nm was used for measurement.

(4) Adhesive strength (unit: gf/inch): Adhesive strength is the 180° adhesive strength between the adhesive film and the glass plate (non-alkali glass plate) and was measured based on JIS C2107:2011 standard. The adhesive sheet was cut into a size of 25 mm long by 100 mm wide, the second release film was peeled off and attached to a glass plate [35 mm long by 110 mm wide], and the first release film was peeled off from the adhesive film. With a 30 kgf load cell, the glass plate and the adhesive film are connected to the upper jig and the lower jig of the tensile test measuring machine, respectively, and the adhesive film is removed from the glass plate at a tensile speed of 300 mm / min, a tensile angle of 180 °, and a tensile temperature of 25 ° C. The load (adhesive strength) when peeled was measured.

(5) Durability: Cut the adhesive sheet into 150 mm wide × 90 mm long, remove the second release film, attach it to one side of the glass plate (non-alkali glass plate) [170 mm long × 110 mm wide], 4 to 5 kg A test piece was prepared by applying a pressure of /cm ² and removing the first release film. After this test piece was left at 85° C. for 500 hours (heat resistance reliability) and then at room temperature for 1 hour, the appearance was evaluated according to the following criteria. After leaving this test piece in a constant temperature chamber at 85° C. and 95% RH for 500 hours (humidity resistance reliability) and then at room temperature for 1 hour, the appearance was evaluated according to the following criteria:
⊚: No bubbles or floats ◯: Slight bubbles or floats △: Some bubbles or floats ×: Both bubbles and floats are generated and cannot be used.

(6) Degree of adhesion to the patterned structure: An acrylic organic pattern structure having a pattern surface with a pattern interval of 500 μm and a step of 10 μm was prepared, and the adhesive surface of the adhesive film was laminated on the pattern surface. After that, it was autoclaved (50° C., 5 bar, 1000 seconds), and the degree of filling of the steps was observed using a microscope and evaluated according to the following criteria:
◎: Completely filled with no air bubbles ○: Filled 90% or more with no air bubbles △: Partially filled with air bubbles at least 50% ×: Many air bubbles and less than 50% filled there is

As shown in Table 2 above, the adhesive film of the present invention has a high refractive index. Therefore, although not shown in Table 2 above, when applied to an optical display device, the optical efficiency of incident light can be increased. As shown in Table 2 above, the adhesive film of the present invention has excellent adhesion to the patterned surface. Thus, although not seen in Table 2 above, minimizing the non-adhered area between the patterned surface and the adhesive film almost eliminates the problem of low light efficiency. As shown in Table 2 above, the adhesive film of the present invention is excellent in wet heat resistance reliability and heat resistance reliability. Thus, although not seen in Table 2 above, detachment and/or separation between the patterned optical element and other optical elements laminated on the top surface of the optical element, such as a polarizer, is prevented to prevent the display device from reliability can be improved.

Therefore, the present invention can provide an adhesive film that enhances the optical efficiency of incident light. In addition, the present invention can provide a pressure-sensitive adhesive film that exhibits significantly superior adhesion to patterned optical elements. In addition, the present invention can provide an adhesive film that has high peel strength and excellent heat resistance reliability and moist heat resistance reliability. Furthermore, the present invention can provide an adhesive film that is almost free from the problem of matching compatibility with inorganic particles and the problem of an increase in production cost of the adhesive film.

On the other hand, the pressure-sensitive adhesive films of Comparative Examples, which did not satisfy at least one of the gel fraction range and the initial decomposition rate range of the present invention, could not obtain the effects of the present invention.

Simple variations or modifications of the present invention can be readily implemented by those of ordinary skill in the art and all such variations and modifications are considered within the scope of the present invention.

100 organic light emitting device,
200 inorganic layer,
300 low refractive index organic layer,
400, 500 high refractive index organic layers.

Claims (13)

A pressure-sensitive adhesive film obtained by curing a pressure-sensitive adhesive composition containing a polymer of a monomer mixture containing one or more aromatic group-containing (meth)acrylates,
The adhesive film has a refractive index of 1.55 or more, an initial decomposition rate of 10% to 20%, and a gel fraction of 50% to 70%. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive film has a peel strength to a glass plate of 800 gf/inch or more. The adhesive film according to claim 1, which has a glass transition temperature of -5°C to 20°C. The adhesive film according to claim 1, wherein the adhesive film does not contain high refractive index inorganic particles. The adhesive film according to claim 1, wherein the aromatic group-containing (meth)acrylate has a homopolymer glass transition temperature of 0°C to 40°C. The adhesive film according to claim 1, wherein the aromatic group-containing (meth)acrylate contains a compound represented by the following chemical formula 2:

In the chemical formula 2,
X is a single bond, an alkylene group having 1 to 5 carbon atoms, or an oxygen atom (O),
Y is a hydrogen atom or a methyl group,
R ₁ is an alkyl group having 1 to 10 carbon atoms, a halogen atom, or an aryl group having 6 to 20 carbon atoms,
n is an integer from 0 to 5,
R ₂ is an alkylene group having 1 to 10 carbon atoms or a (poly)alkyleneoxy group having 1 to 30 carbon atoms. The aromatic group-containing (meth)acrylate includes one or more of phenylbenzyl acrylate, phenoxybenzyl (meth)acrylate, monoethoxylated phenylphenoxy (meth)acrylate, and poly(ethoxylated)phenylphenoxy (meth)acrylate. , The pressure-sensitive adhesive film of claim 1. The adhesive film according to claim 1, wherein the monomer mixture contains a (meth)acrylic monomer having a hydroxyl group. The adhesive film according to claim 8, wherein the (meth)acrylic monomer having a hydroxyl group has a homopolymer glass transition temperature lower than that of the aromatic group-containing (meth)acrylic monomer. The monomer mixture contains 75% to 95% by mass of one or more aromatic group-containing (meth)acrylates, and the hydroxyl group-containing (meth)acrylic The pressure-sensitive adhesive film according to claim 8, containing a monomer content of 5% by mass to 25% by mass. The pressure-sensitive adhesive film according to claim 1, wherein the pressure-sensitive adhesive composition further contains one or more of an isocyanate curing agent and a silane coupling agent. An optical member comprising the adhesive film according to any one of claims 1 to 11. An optical display device comprising the adhesive film according to any one of claims 1 to 11.

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