KR102489566B1 - Multilayer sealing adhesive film with excellent barrier properties and manufacturing method thereof - Google Patents

Abstract

Disclosed herein is a multilayer encapsulation adhesive film with improved adhesive strength and excellent barrier properties, and a manufacturing method thereof.

Description

Multilayer sealing adhesive film with excellent barrier properties and its manufacturing method {MULTILAYER SEALING ADHESIVE FILM WITH EXCELLENT BARRIER PROPERTIES AND MANUFACTURING METHOD THEREOF}

The present specification relates to a multilayer encapsulation adhesive film with improved adhesive strength and excellent barrier properties and a method for manufacturing the same.

Compared to existing displays such as LCD, the currently commercialized OLED display has the advantage of having a simple structure due to self-luminescence and reducing the number of panels by about half, as well as various advantages such as colors close to natural colors, high contrast ratio, and reduced power consumption. market needs are shifting.

However, OLED has a fatal problem of being vulnerable to moisture and gas, and various encapsulation technologies have been developed to overcome this problem. A thin metal barrier layer for thin film encapsulation and panels are attached to large displays such as TVs, and an encapsulation adhesive film for OLED is essential to remove moisture and gas generated in the panel.

On the other hand, the conventional encapsulation adhesive film for OLED has generally been composed of only an adhesive layer containing a moisture absorbent for removing moisture, but a large amount of absorbent powder, mainly metal oxide or metal salt, causes a decrease in adhesion to the substrate, Moisture permeation may occur rapidly, which may cause reliability problems.

Therefore, there is a demand for the development of a film capable of sufficiently removing moisture while having excellent adhesion.

WO2013125874A1

The present specification is intended to provide an encapsulation film and a method for manufacturing the same, which can prevent the rapid occurrence of moisture penetration in the initial stage during the accelerated test evaluation after encapsulating the OLED panel.

In exemplary embodiments of the present invention, the first adhesive layer containing a tackifier; a second adhesive layer located on the first adhesive layer and containing a tackifier; and a third adhesive layer disposed on the second adhesive layer and including a tackifier, wherein the second adhesive layer further includes a moisture absorbent.

In another exemplary embodiment of the present invention, as a method for manufacturing the above-described encapsulation adhesive film, preparing a composition for a first adhesive layer, a composition for a second adhesive layer, and a composition for a third adhesive layer; Injecting the compositions into a multi-manifold die; and forming a first adhesive layer, a second adhesive layer, and a third adhesive layer at the same time using the multi-manifold die.

In one aspect of the present invention, an adhesive encapsulation film having improved adhesion between a barrier layer and an encapsulation adhesive film for OLED is provided.

In another aspect of the present invention, an encapsulating adhesive film for removing moisture and gas generated in an OLED panel is provided.

In another aspect of the present invention, as a multi-layer form in which an adhesive layer having high adhesive strength is formed on both outer surfaces, an encapsulation adhesive film capable of preventing early moisture penetration by improving adhesion is provided.

In another aspect of the present invention, a method for manufacturing an encapsulating adhesive film capable of improving productivity and securing product cost competitiveness by manufacturing a multi-layered adhesive film in one process is provided.

1 is a graph showing the change in WVT value over time of an adhesive film for encapsulation according to an embodiment of the present invention.
2 is a structural diagram of a conventional (comparative example) sealing adhesive film.
3 is a structural diagram of an adhesive film for encapsulation according to an embodiment of the present invention.
4 is a schematic diagram of a multi-manifold die used in a manufacturing method according to an embodiment of the present invention.

In this specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

Hereinafter, exemplary embodiments of the present invention are described in detail.

3 is a structural diagram of an adhesive film for encapsulation according to an embodiment of the present invention.

In exemplary embodiments of the present invention, the first adhesive layer 10 including a tackifier; a second adhesive layer 20 located on the first adhesive layer and containing a tackifier; and a third adhesive layer 30 located on the second adhesive layer and containing a tackifier, wherein the second adhesive layer further includes a moisture absorbent.

Conventional OLED encapsulation adhesive films have generally been composed of an adhesive layer containing a moisture absorbent to remove moisture, but a large amount of absorbent powder, mainly metal oxide or metal salt, causes a decrease in adhesion to the substrate, Moisture permeation may occur rapidly, which may cause reliability problems.

In one aspect of the present invention, by constituting an adhesive layer with improved adhesion that includes a moisture absorbent only in the inner layer (second adhesive layer) and does not contain a moisture absorbent in both outer layers (first adhesive layer and third adhesive layer), the substrate and the metal layer meeting the film It is possible to secure high product reliability by improving the adhesion of the product and preventing moisture penetration that may occur when the adhesion is reduced.

In an exemplary embodiment, the first adhesive layer, the second adhesive layer, and the third adhesive layer may each independently further include one or more selected from the group consisting of a polyolefin-based binder, an acrylic monomer, and a photoinitiator. The first adhesive layer and the third adhesive layer on the outer surface may have the same composition or may be made of different compositions, but unlike the second adhesive layer, they do not contain a moisture absorbent.

In one embodiment, the polyolefin-based binder may correspond to all general polyolefin-based binders known in the art. In addition, the polyolefin-based resin may be a polyethylene-based resin or a polypropylene-based resin, and may be a modified polyethylene resin, a modified polypropylene-based resin, an ethylene copolymer, or a propylene copolymer. It may be polyolefin (TPO) or polyolefin elastomer (POE), and may be EPDM or Butyl Rubber.

In one embodiment, the acrylic monomer may be an acrylate-based monomer or a methacrylate-based monomer, for example, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, t-butylamino It may be ethyl methacrylate, for example, as an acrylic monomer having high water resistance and chemical resistance, it may be an acrylic monomer having a bifunctional group or more, preferably tricyclodecane dimethanol diacrylate (common name TCDDA).

In one embodiment, the photoinitiator can be used in the general 300 ~ 400nm wavelength band, for example, benzoin methyl ether, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, α,α-methoxy-α-hydroxyacetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-morphonyl)phenyl]-1 - It may include at least one selected from the group consisting of butanone, 2,2-dimethoxy-2-phenylacetophenone, oxime ester-based, and the like.

Also, for example, it may be 1-Hydroxy-cyclohexyl-phenyl-ketone or Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, preferably Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (common name TPO). can

In an exemplary embodiment, the moisture absorbent may include a metal oxide.

In an exemplary embodiment, the desiccant may be lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), barium oxide (BaO), calcium oxide (CaO), and magnesium oxide (MgO). It may include one or more selected from the group consisting of, for example, may include calcium oxide, and in the case of calcium oxide (CaO), color change can be easily observed with the naked eye when moisture is contained, which is preferable.

In an exemplary embodiment, the thickness of the first adhesive layer and the third adhesive layer may be the same as or different from each other, each independently 5 to 50 μm, and the thickness of the second adhesive layer may be 20 to 1,000 μm. For example, the thickness of the first adhesive layer and the third adhesive layer are the same as or different from each other, and each independently may be 5 to 50 um, preferably 5 to 20 um, and the thickness of the second adhesive layer is 20 to 1,000 um It may be, and preferably may be 20 ~ 100 um.

When the thickness of the first adhesive layer or the third adhesive layer is less than 5um, surface roughness may increase due to the influence of a filler such as a moisture absorbent, resulting in low adhesion, and when it is higher than 20um, moisture absorption performance may be reduced.

When the thickness of the second adhesive layer is less than 20um, deterioration in moisture absorption performance may occur, and when it is greater than 100um, the overall thickness of the panel increases, which is not preferable.

In an exemplary embodiment, the adhesive film for encapsulation may further include a base film positioned on the first adhesive layer or the third adhesive layer.

In an exemplary embodiment, the base film may be polyethyleneterephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), or polymethyl methacrylate (PMMA; Poly(methyl methacrylate)), polyimide (PI; polyimide), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene 2,6-dicarboxyl naphthalate (PEN; It may include one or more selected from the group consisting of polyethylene 2,6-dicarboxyl naphthalate), polyethersulfone (PES), polyester, and polystyrene (PS). It may be PET coated with silicone.

In an exemplary embodiment, the adhesive film for encapsulation may be for OLED.

4 is a schematic diagram of a multi-manifold die used in a manufacturing method according to an embodiment of the present invention.

In another exemplary embodiment of the present invention, as a method for manufacturing the above-described encapsulation adhesive film, preparing a composition for a first adhesive layer, a composition for a second adhesive layer, and a composition for a third adhesive layer; Injecting the compositions into a multi-manifold die; and forming a first adhesive layer, a second adhesive layer, and a third adhesive layer at the same time using the multi-manifold die.

As the number of layers of the film increases, the manufacturing process increases and the production yield may decrease. In the present specification, it is possible to improve productivity and product cost competitiveness by utilizing a multi-manifold die so as to manufacture multiple layers at once.

In one embodiment, the composition for the first adhesive layer and the composition for the third adhesive layer may each independently include an adhesion agent, a polyolefin-based binder, an acrylic monomer, and a photoinitiator.

In one embodiment, the composition for the second adhesive layer may include a moisture absorbent, a tackifier, a polyolefin-based binder, an acrylic monomer, and a photoinitiator.

In one embodiment, the content of the acrylic monomer may be 0.1 to 2% by weight based on the total weight of the composition for the first adhesive layer or the composition for the third adhesive layer.

In one embodiment, the amount of the photoinitiator may be 1 to 20 parts by weight based on 100 parts by weight of the acrylic monomer.

In an exemplary embodiment, the difference between the viscosity of the composition for the first adhesive layer or the composition for the third adhesive layer and the viscosity of the composition for the second adhesive layer may be 100 cps or more, for example, 100 cps or more, 200 cps or more, or 300 cps. or more, 400 cps or more, 500 cps or more, 600 cps or more, 700 cps or more, 800 cps or more, or 900 cps or more.

In manufacturing the adhesive film, when the compositions for the 1st-3rd adhesive layers are coated on a substrate such as release PET in a Multi Manifold Die, in order to prevent the compositions for the 1st-3rd adhesive layers from being mixed with each other, the viscosity of the composition for the 2nd adhesive layer is relatively high, the viscosity of the composition for the first adhesive layer and the composition for the third adhesive layer should be designed to be relatively low compared to the viscosity of the composition for the second adhesive layer.

Hereinafter, specific embodiments according to exemplary embodiments of the present invention will be described in more detail. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and only the following examples will complete the disclosure of the present invention and at the same time, common in the art. It will be understood that the intention is to facilitate practice of the invention to those skilled in the art.

Example

1-1. Preparation of coating solution No. 1 (composition for the first and third adhesive layers)

EPDM, a type of polyolefin binder, and 1:2:4 tackifier are mixed with 0.5wt% of acrylic monomer and 10wt% of photoinitiator compared to 100wt% of acrylic monomer. A burn coating solution was prepared. The products used were specifically:

-EPDM : High diene type product containing about 10wt% of ethylene norbornene

-Butyl Rubber : Copolymer of Isobutlyene and Isoprene (30~55MU (pattern viscosity))

-Tackifier: Mixing two types with low electrical polarity and softening points of 90℃ and 100℃

-Acrylic monomer: Tricyclodecane dimethanol diacrylate (common name TCDDA)

-Photoinitiator: Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (common name TPO)

1-2. Preparation of coating solution No. 2 (composition for second adhesive layer)

Coating solution No. 2 was prepared by mixing CaO with the coating solution No. 1 in a ratio of 1:1.

1-3. film manufacturing

The coating liquid was injected into the Multi Manifold Die to form a 1/2/3 coating layer (adhesive layer), and PET coated with release silicone was used as a support film for coating. /3 The adhesive layer was coated and dried to prepare an encapsulation adhesive film.

2. Comparative Example 1

After preparing the coating solution in the same manner as in Example, only coating solution No. 2 (composition for the second adhesive layer containing a moisture absorbent) was coated, and WTV of a single layer film was performed. (See FIG. 2)

3. Comparative Example 2

After preparing the coating solution in the same manner as in Example, coating only the coating solutions 1 and 2 (the composition for the first adhesive layer without a moisture absorbent and the composition for the second adhesive layer including a moisture absorbent) were applied to obtain WTV of the two-layered film. proceeded.

test example

1. Water Through Velocity (WTV) evaluation

After laminating alkali-free glass on both outer surfaces of the films of Example 1 and Comparative Examples 1 and 2, they were placed in a reliability chamber at a temperature of 85 ° C and a humidity of 85%, and the penetration length of moisture up to 1000 hours in units of 100 hours was measured under a microscope. measured through

2. Evaluation of adhesion to metal substrates

After laminating an encapsulation adhesive film on a cleaned metal substrate (Invar), a specimen was prepared by laminating Tesa 07475 tape on the opposite side, and after fixing one side of the metal to UTM, an angle of 180° was made with the Tesa tape. was peeled off to evaluate the adhesive strength.

The results of Test Examples 1 and 2 are shown in Table 1 and FIG. 1 below.

℃ metal base
adhesion
(Kgf/25mm) WVT (μm/hrs) 100
hour 200
hour 300
hour 400
hour 500
hour 600
hour 700
hour 800
hour 900
hour 1000
hour Example 1.9 533 702 752 799 848 947 998 1032 1097 1125 Comparative Example 1 1.1 882 995 1042 1127 1172 1273 1398 1450 1485 1554 Comparative Example 2 1.3 775 901 952 989 1083 1144 1241 1296 1343 1377

Adhesion to the metal substrate was evaluated in the order of Example> Comparative Example 2> Comparative Example 1, and it could be seen from the graph that the WVT result progressed up to 1000 hours showed a similar trend. In particular, in Comparative Example 1 and Comparative Example 2, it was confirmed that the WTV increased rapidly at the beginning near 100 hours. In conclusion, it was confirmed that the three-layer structure product with improved adhesiveness has an effect of somewhat alleviating the problem of moisture absorption in the early stage.

10: first adhesive layer
20: second adhesive layer
30: third adhesive layer

Claims (13)

As a composition for forming a multilayer encapsulating adhesive film,
It includes a composition for a first adhesive layer, a composition for a second adhesive layer, and a composition for a third adhesive layer,
The composition for the first adhesive layer, the composition for the second adhesive layer, and the composition for the third adhesive layer are not mixed with each other,
The composition for the first adhesive layer, the composition for the second adhesive layer, and the composition for the third adhesive layer further include a polyolefin-based binder, an acrylic monomer, and a photoinitiator,
The polyolefin binder is a mixture of ethylene propylene diene monomer (EPDM) and butyl rubber,
The acrylic monomer is tricyclodecane dimethanol diacrylate,
The photoinitiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide,
The viscosity of the composition for the second adhesive layer is higher than the viscosity of the composition for the first adhesive layer and the composition for the third adhesive layer, the composition for forming an encapsulation adhesive film. An encapsulation adhesive film formed from the composition of claim 1,
a first adhesive layer formed from the composition for the first adhesive layer;
a second adhesive layer formed from the composition for the second adhesive layer; and
A third adhesive layer formed from the composition for the third adhesive layer; containing, the sealing adhesive film. According to claim 2,
A first adhesive layer containing a tackifier;
a second adhesive layer located on the first adhesive layer and containing a tackifier; and
A third adhesive layer located on the second adhesive layer and including a tackifier;
The first adhesive layer, the second adhesive layer, and the third adhesive layer further include a polyolefin-based binder, an acrylic monomer, and a photoinitiator,
The polyolefin binder is a mixture of ethylene propylene diene monomer (EPDM) and butyl rubber,
The acrylic monomer is tricyclodecane dimethanol diacrylate,
The photoinitiator is diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide,
The second adhesive layer further comprises a moisture absorbent, the sealing adhesive film. delete According to claim 3,
The moisture absorbent contains a metal oxide, the sealing adhesive film. According to claim 3,
The desiccant is selected from the group consisting of lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), barium oxide (BaO), calcium oxide (CaO), and magnesium oxide (MgO) An encapsulation adhesive film comprising at least one. According to claim 3,
The thickness of the first adhesive layer and the third adhesive layer are the same as or different from each other, and each independently is 5 to 50 μm,
The thickness of the second adhesive layer is 20 to 1,000 μm, the encapsulation adhesive film. According to claim 3,
The sealant adhesive film further comprises a base film positioned on the first adhesive layer or the third adhesive layer, the sealant adhesive film. According to claim 8,
The base film is polyethyleneterephthalate (PET), polyethylene (PE), polypropylene (PP), polycarbonate (PC), poly(methyl methacrylate) (PMMA) , polyimide (PI; polyimide), oriented polypropylene (OPP), biaxially oriented polypropylene (BOPP), polyethylene 2,6-dicarboxyl naphthalate (PEN; Naphthalate), polyethersulfone (PES; polyethersulfone), polyester (Polyester) and polystyrene (PS; Polystyrene) containing at least one selected from the group consisting of, the encapsulation adhesive film. According to claim 3,
The encapsulation adhesive film is for OLED, the encapsulation adhesive film. A display device comprising the encapsulation adhesive film of claim 3. A method for producing the sealing adhesive film according to any one of claims 2, 3, and 5 to 10,
Preparing a composition for a first adhesive layer, a composition for a second adhesive layer, and a composition for a third adhesive layer; containing, a method for manufacturing an adhesive film for sealing. According to claim 12,
Injecting the compositions into a multi-manifold die; and
Forming a first adhesive layer, a second adhesive layer, and a third adhesive layer at the same time using the multi-manifold die; further comprising a method for manufacturing an encapsulation adhesive film.

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