KR102197326B1 - Adhesive Composition and Adhesive Sheet Using the Same - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition comprising polybutadiene, polyfunctional (meth)acrylate and a photoinitiator. The pressure-sensitive adhesive composition according to the present invention has excellent barrier properties and durability and can be applied to encapsulate and protect organic electronic devices exhibiting moisture fragility such as OLEDs.

Description

Adhesive Composition and Adhesive Sheet Using the Same

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet using the same, and more particularly, to a pressure-sensitive adhesive composition excellent in barrier properties and durability, and a pressure-sensitive adhesive sheet using the same.

Organic Light-Emitting Diode (OLED), which is attracting attention as a next-generation flat panel display, is a diode-type device made by depositing an organic material between the anode and the cathode or forming a film through a solution process and stacking it. . Since OLED is a self-luminous type, it has excellent viewing angle and contrast ratio, and simplification of the process makes it possible to reduce weight and thickness.

However, OLEDs are vulnerable to external factors such as moisture or oxygen. In particular, in the OLED, the organic material layer may be peeled off under the influence of moisture at the interface with the electrode, or the electrode may be oxidized by moisture to increase the resistance value, or the organic material itself may be deteriorated, resulting in loss of light-emitting function or reduction in brightness. Accordingly, in order to protect the OLED from the external environment, an encapsulation structure in which the OLED formed on the substrate is fixed with an adhesive sheet having barrier properties is used.

Therefore, interest in a pressure-sensitive adhesive sheet having increased barrier properties has recently increased. For example, Korean Patent Publication No. 10-2015-0079567 discloses a pressure-sensitive adhesive sheet having a barrier property formed from a pressure-sensitive adhesive composition comprising a polyisobutylene-based resin, a styrene-based copolymer, and a tackifier. However, when the pressure-sensitive adhesive sheet is applied to an OLED, it is difficult to secure durability as well as barrier properties.

Republic of Korea Patent Publication No. 10-2015-0079567

One object of the present invention is to provide a pressure-sensitive adhesive composition having excellent barrier properties and durability.

Another object of the present invention is to provide a pressure-sensitive adhesive sheet formed by using the pressure-sensitive adhesive composition.

On the one hand, the present invention provides a pressure-sensitive adhesive composition comprising polybutadiene, polyfunctional (meth)acrylate and a photoinitiator.

In one embodiment of the present invention, the polybutadiene may be hydrogenated polybutadiene.

In one embodiment of the present invention, the polyfunctional (meth)acrylate may be a trifunctional to 6functional (meth)acrylate.

In one embodiment of the present invention, the pressure-sensitive adhesive composition may further include plate-shaped inorganic particles.

On the other hand, the present invention provides a pressure-sensitive adhesive sheet formed by using the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition according to the present invention not only has excellent barrier properties, including polybutadiene, particularly hydrogenated polybutadiene, but also can secure durability due to crosslinking of trifunctional or higher polyfunctional (meth)acrylates, and thus moisture such as OLED. It can be applied to encapsulate and protect vulnerable organic electronic devices.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention relates to a pressure-sensitive adhesive composition comprising polybutadiene, polyfunctional (meth)acrylate and a photoinitiator.

In one embodiment of the present invention, the polybutadiene is a polymer obtained by polymerizing 1,3-butadiene as a monomer, and serves as a binder resin.

The polybutadiene may be hydrogenated polybutadiene. Hydrogenated polybutadiene is advantageous in terms of barrier properties because the concentration of double bonds decreases.

The polybutadiene may be a polymer including one or more repeating units selected from Formulas 1 and 2 below.

[Formula 1]

[Formula 2]

In the above formula,

The double line of solid and dotted lines represents a single bond or a double bond,

In the case of a double bond, a broken line represents either a cis or a trans form.

When the double line of the solid line and the dotted line represents a double bond, it is hydrogenated polybutadiene, and when it represents a single bond, it is hydrogenated polybutadiene. In the case of hydrogenated polybutadiene, 100% of the double bond does not need to be hydrogenated, and the residual ratio of the double bond is not particularly limited.

When the repeating unit of Formula 2 has a double bond, a cis form, a trans form, or a combination thereof may exist.

The repeating unit of Formula 1 is formed by a 1,2-bond of 1,3-butadiene, and the repeating unit of Formula 2 is formed by a 1,4-bond of 1,3-butadiene.

The ratio of the repeating unit of Formula 1 and the repeating unit of Formula 2 is 0 to 100 mol%, respectively. That is, the polybutadiene may have only the repeating unit of Formula 1 or the repeating unit of Formula 2, or both of the repeating unit of Formula 1 and the repeating unit of Formula 2.

The ratio of the repeating unit of Formula 1 and the repeating unit of Formula 2 may vary depending on the catalyst used during polymerization, and a specific repeating unit may predominate, or polybutadiene may be substantially formed of a specific repeating unit. For example, when 1,3-butadiene is polymerized using a Ziegler catalyst, a lithium catalyst, or a radical polymerization initiator, polybutadiene polymerized mainly by 1,4-bonds can be obtained, and 1,3-butadiene is used as a sodium catalyst. In the case of polymerization in the presence of a polybutadiene polymerized mainly by 1,2-bonds can be obtained.

Hydrogenated polybutadiene can be obtained by hydrogenating polybutadiene polymerized as described above. The hydrogenation reaction may be performed by a method known in the art in the presence of a hydrogenation catalyst such as Raney Nickel, platinum, or titanium.

The polybutadiene may be obtained commercially or may be prepared and used by a method known in the art. Commercially available polybutadienes include Nippon Soda's BI-2000, BI-3000, B-1000, B-2000, and B-3000.

The polybutadiene may have a number average molecular weight (in terms of polystyrene) of 1,000 to 5,000 measured by gel permeation chromatography (GPC). If the number average molecular weight of the polybutadiene is less than 1,000, the heat resistance of the pressure-sensitive adhesive may decrease, and if it exceeds 5,000, the viscosity of the pressure-sensitive adhesive composition may increase, resulting in coating unevenness.

In one embodiment of the present invention, the polyfunctional (meth)acrylate is a component for enhancing durability of the pressure-sensitive adhesive by crosslinking, and may be a polyfunctional (meth)acrylate having trifunctional or higher functions. For example, the polyfunctional (meth)acrylate may be a trifunctional to 6functional (meth)acrylate.

Specifically, as the polyfunctional (meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol Tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, Trifunctional (meth)acrylates such as glycerol tri(meth)acrylate; Tetrafunctional (meth)acrylates such as diglycerine tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate; 5-functional (meth)acrylates, such as propionic acid-modified dipentaerythritol penta (meth)acrylate; And 6-functional (meth)acrylates such as caprolactone-modified dipentaerythritol hexa (meth)acrylate, and the like.

The polyfunctional (meth)acrylate may be included in an amount of 10 to 100 parts by weight based on 100 parts by weight of the total polybutadiene. If the content of the polyfunctional (meth)acrylate is less than 10 parts by weight, the amount of monomer that can be crosslinked is small, so the ability to immobilize polybutadiene, which is a binder resin, may be weakened, resulting in a decrease in durability, and if it exceeds 100 parts by weight Due to high curing, adhesive strength may decrease, resulting in decreased adhesion durability or increased moisture permeability, resulting in a decrease in barrier properties.

In one embodiment of the present invention, the photoinitiator is, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone. , Dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenylketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2 -(Hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-bis(diethylamino)benzophenone (EAB-F), dichlorobenzophenone, 2-methyl anthraquinone, 2 -Ethyl anthraquinone, 2-t-butyl anthraquinone, 2-amino anthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2-chloro thioxanthone, 2,4-dimethyl thioxanthone, 2 ,4-diethyl thioxanthone (DETX), 4-isopropyl thioxanthone (ITX), benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl- 1[4-(1-methylvinyl)phenyl]propane], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2-(3,4-methylenedioxyphenyl)-4,6-bis( Trichloromethyl)-1,3,5-triazine, 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbiimidazole (HABI-101), 2, 2'-bis(2-methoxyphenyl)-4,4',5,5'-tetraphenylbiimidazole (HABI-107), 2,2',4-tris(2-chlorophenyl)-5- (3,4-dimethoxyphenyl)-4',5'-diphenylbiimidazole (TCDM), and the like. These may be used alone or in combination of two or more.

The photoinitiator may be included in an amount of 0.01 to 5.0 parts by weight based on 100 parts by weight of the total of the polyfunctional (meth)acrylate. If the content of the photoinitiator is less than 0.01 parts by weight, it may be difficult to effectively initiate the crosslinking reaction of the polyfunctional (meth)acrylate, and if it exceeds 5.0 parts by weight, discoloration may occur due to the residual initiator, and durability may be deteriorated.

The pressure-sensitive adhesive composition according to an embodiment of the present invention may further include plate-shaped inorganic particles.

The plate-shaped inorganic particles are a component that blocks or interferes with the movement of moisture, and may be, for example, nanoclay. Layered silicate may be used as the nano-clay, and as such layered silicate, montmorillonite, saponite, hectorite, vermiculite, bentonite, attapulgite ( attapulgite), sepiolite, halloysite, and the like.

The nanoclay may be modified with an organic modifier in order to improve compatibility with a binder resin. The organic modifiers include dimethyl benzyl hydrogenated tallow quaternary ammonium ion, bis (hydrogenated tallow) dimethyl quaternary ammonium ion, methyl tallow bis-2-hydroxyethyl quaternary ammonium ion, dimethyl hydrogenated tallow 2-ethylhexyl Quaternary ammonium ions or dimethyl dehydrogenated tallow quaternary ammonium ions, and the like.

The plate-shaped inorganic particles may be included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the total polybutadiene. If the content of the plate-shaped inorganic particles is less than 1 part by weight, the effect of improving the barrier properties may be insufficient, and if it exceeds 20 parts by weight, the viscosity of the pressure-sensitive adhesive composition may increase, resulting in coating unevenness, and adhesion durability due to lower wettability and lower adhesive strength. This can be degraded.

In addition to the above components, the pressure-sensitive adhesive composition according to an embodiment of the present invention includes a silane coupling agent, a tackifier resin in order to control adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, antistatic properties, etc. , Antioxidants, corrosion inhibitors, leveling agents, surface lubricants, dyes, pigments, antifoaming agents, fillers, light stabilizers, may further include additives such as antistatic agents.

One embodiment of the present invention relates to a pressure-sensitive adhesive sheet formed by using the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive sheet according to an embodiment of the present invention may be a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to the present invention interposed between two base films.

The base film may be a polyolefin-based film, a polyester-based film, an acrylic film, a styrene-based film, an amide-based film, a polyvinyl chloride film, a polyvinylidene chloride film, a polycarbonate film, and the like, which are silicone-based, fluorine-based, and silica It may have been suitably molded out by powder or the like.

The pressure-sensitive adhesive layer can be formed by coating an optically transparent pressure-sensitive adhesive composition on a single base film. The coating method is not particularly limited as long as it is a method known in the art, and for example, a bar coater, air knife, gravure, reverse roll, kiss roll, spray, blade, die coater, casting, spin coating, etc. may be used. . Specifically, a pressure-sensitive adhesive composition is applied on one base film, dried at 30 to 150° C. for 1 second to 2 hours, preferably 5 seconds to 1 hour, and then about 100 to 2000 mJ/cm 2, preferably 200 It can be formed by curing by irradiation with an ultraviolet irradiation dose of 1500 mJ/cm 2.

The thickness of the pressure-sensitive adhesive layer may be 5 to 200 μm, preferably 5 to 100 μm. If the thickness of the pressure-sensitive adhesive layer is less than 5 μm, the barrier property may be deteriorated or it may be difficult to buffer external impacts. If it exceeds 200 μm, the unit price may increase due to the increase in the amount of material used. Surface unevenness may occur.

The pressure-sensitive adhesive sheet according to an embodiment of the present invention may improve adhesion by surface-treating the pressure-sensitive adhesive layer before bonding.

The surface treatment method is not particularly limited, and the surface of the pressure-sensitive adhesive layer may be activated by a method such as corona discharge treatment, plasma treatment, ultraviolet irradiation, electron beam irradiation, or application of an anchoring agent.

The pressure-sensitive adhesive sheet according to an embodiment of the present invention can be applied to an organic light emitting diode (OLED), a solar cell, a secondary battery, a touch panel, and the like. In particular, the pressure-sensitive adhesive composition according to an embodiment of the present invention may be used to encapsulate and protect OLEDs that are sensitive to external factors such as moisture or oxygen.

Hereinafter, the present invention will be described in more detail by Examples, Comparative Examples and Experimental Examples. These Examples, Comparative Examples and Experimental Examples are for illustrative purposes only, and it is obvious to those skilled in the art that the scope of the present invention is not limited thereto.

Example 1 to 4 and Comparative example 1 to 3: Preparation of pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet

Polybutadiene, polyfunctional (meth)acrylate, and a photoinitiator were mixed in the composition shown in Table 1 (unit: parts by weight), and then diluted to a concentration of 28% by weight in ethyl acetate to prepare a pressure-sensitive adhesive composition.

Example Comparative example One 2 3 4 One 2 3 Binder resin Hydrogenated polybutadiene 100 100 100 100 - 100 100 Polyisobutylene - - - - 100 - - Trifunctional (meth)acrylate 20 5 30 20 20 - - Bifunctional (meth)acrylate - - - - - 20 - Epoxy compound - - - - - - 20 Plate-shaped inorganic particles 2 2 2 - 2 2 2 Photoinitiator Radical photopolymerization initiator 0.3 0.3 0.3 0.3 0.3 0.3 - Photoacid generator - - - - - - 0.3

Hydrogenated (hydrogenated) polybutadiene: BI-2000 (number average molecular weight: 2,100, Nippon Soda Corporation)

Polyisobutylene (weight average molecular weight: 200,000, Aldrich)

Trifunctional (meth)acrylate: trimethylolpropane triacrylate (TMPTA)

Bifunctional (meth)acrylate: hexamethylenediol diacrylate (HDDA)

Epoxy compound: N,N,N,N'-tetraglycidyl-m-xylenediamine (N,N,N,N'-tetraglycidyl-m-xylenediamine (Tetrad-X, Mitsubishi Gas)

Plate-shaped inorganic particles: Nano clay modified with bis (hydrogenated tallow) dimethyl quaternary ammonium ion (Cloisite93A, Southern Clay Products)

Radical photopolymerization initiator: 1-hydroxycyclohexyl phenylketone (Irg184, Swiss Civas Specialty Chemicals)

Photo acid generator: triphenylsulfonium hexafluorophosphate

The pressure-sensitive adhesive composition prepared above was applied to a thickness of 100 μm on a release film coated with a silicone release agent, and dried at 130° C. for 5 minutes to form a pressure-sensitive adhesive layer, and after bonding the release film thereon, the following conditions were applied. The adhesive sheet was prepared by UV treatment as well.

<Ultraviolet ray treatment conditions>

UV irradiator: high pressure mercury lamp

Irradiation conditions: Light quantity (UVA) = 1500 mJ/cm ²

Experimental example One:

The physical properties of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

(1) moisture Barrier characteristic

A specimen was prepared by peeling the release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples, laminating the pressure-sensitive adhesive side with a porous film, and then peeling the release film on the other side. Then, the moisture permeability in the thickness direction of the specimen was measured while the specimen was placed under conditions of 37°C and 100%RH. The moisture permeability was measured according to ASTM F1249.

(2) Durability (heat resistance, Moist heat resistance )

The release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples was peeled off, corona-treated on the pressure-sensitive adhesive side, and then bonded with a 40 μm COP film to cut the prepared pressure-sensitive adhesive sheet into a size of 90 mm×170 mm, and the remaining release film And then attached to a glass substrate (110 mm×190 mm×0.7 mm) to prepare a specimen. At this time, the applied pressure was 5 kg/㎠ and the clean room was performed to prevent bubbles or foreign matter from occurring. Heat resistance was observed for occurrence of bubbles or peeling after leaving for 500 hours at a temperature of 100°C, and moisture and heat resistance was observed for occurrence of bubbles or peeling after leaving for 500 hours under conditions of 85°C and 85%RH. Was observed.

<Evaluation criteria>

Ⓞ: No air bubbles or peeling.

○: Bubbles or peeling <5

△: 5 ≤ bubbles or peeling <10

×: 10 ≤ bubbles or peeling

(3) adhesion

The release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples was peeled off, corona-treated on the pressure-sensitive adhesive side, bonded with a 38 µm PET film, and cut to a width of 25 mm and a length of 100 mm to prepare the specimen. Was prepared. Subsequently, the release film on the other side was peeled off, and the pressure-sensitive adhesive sheet was attached to the glass using a 2 kg roller according to the regulations of JIS Z 0237. Then, using a TA equipment (Texture Analyzer, manufactured by Stable Micro Systems, UK), the adhesive sheet was peeled from the glass at a peeling rate of 300 mm/min and a peeling angle of 180 degrees to measure adhesion.

division Moisture barrier properties
(g/㎡·day) durability Adhesion (N/25㎜) Heat resistant Moist heat resistance Example 1 6 ○ ○ 25 Example 2 5 ○ ○ 23 Example 3 7 ○ ○ 18 Example 4 9 ○ ○ 19 Comparative Example 1 13 Ⓞ Ⓞ 28 Comparative Example 2 11 △ △ 31 Comparative Example 3 25 Ⓞ × 35

As can be seen in Table 2, the pressure-sensitive adhesive compositions of Examples 1 to 4 using polybutadiene, a trifunctional or higher polyfunctional (meth)acrylate, and a photoinitiator have moisture barrier properties compared to the pressure-sensitive adhesive compositions of Comparative Examples 1 to 3. It was confirmed that it was not only excellent, but also excellent in durability and adhesion.

As described above, a specific part of the present invention has been described in detail, and it is obvious that this specific technology is only a preferred embodiment for those of ordinary skill in the art to which the present invention belongs, and the scope of the present invention is not limited thereto. Do. Those of ordinary skill in the art to which the present invention belongs will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Therefore, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (7)

Including polybutadiene, polyfunctional (meth)acrylate and photoinitiator,
The number average molecular weight of the polybutadiene is 1,000 to 5,000,
The polyfunctional (meth)acrylate is a 3-functional to 6-functional (meth)acrylate pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition of claim 1, wherein the polybutadiene is hydrogenated polybutadiene. delete delete The pressure-sensitive adhesive composition according to claim 1, further comprising plate-shaped inorganic particles. The pressure-sensitive adhesive composition of claim 5, wherein the plate-shaped inorganic particles are nano clays. A pressure-sensitive adhesive sheet formed using the pressure-sensitive adhesive composition of any one of claims 1, 2, 5, and 6.