KR102666668B1 - Both-sided Optical Adhesive Sheet - Google Patents

Abstract

The double-sided adhesive sheet for optical use includes a first film, a second film, and a double-sided adhesive layer bonded between the first film and the second film. The double-sided adhesive layer includes a transparent base layer, a first adhesive layer on which one side is bonded to one side of the transparent base layer and the other side is bonded to the first film, and one side is bonded to the other side of the transparent base layer and the other side is bonded to the first film. It includes a second adhesive layer bonded to the second film.

Description

Both-sided Optical Adhesive Sheet}

The present invention relates to a double-sided adhesive sheet for optics.

A display device or an input device includes a layered structure including a substrate, a film, etc. Such a laminated structure may use a double-sided adhesive sheet with light transparency to join (or bond) adjacent members (substrates, films, etc.) or to fill air gaps between adjacent members. This double-sided adhesive sheet includes a substrate and first and second adhesive layers bonded to both sides of the substrate.

Meanwhile, the touch sensor, a type of input device, is divided into a central display area (View Area) where light transmits and a bezel area at the edge where light is blocked, and a decorative film to block light is attached to the bezel area. It is done.

Looking at conventional display devices, input devices, etc., a decor film is used by combining it with a functional layer such as a polarizing film or a window film using a double-sided adhesive sheet.

However, the thickness of this laminated bonded structure is the combined thickness of the decoration film, double-sided adhesive sheet, and functional layer, resulting in a problem in which the overall thickness increases rapidly. This problem of increased thickness is a major cause of worsening folding properties when using foldable display devices or input devices.

In addition, conventional double-sided adhesive sheets are often discarded without being able to use them because the adhesive layer is exposed to the outside and becomes contaminated during use or storage.

[Prior patent literature]

1. Korean Patent Registration No. 2036463 (Adhesive sheet)

2. Korean Patent Publication No. 2018-0001471 (Optical adhesive sheet, polarizing film with adhesive layer, and liquid crystal display device)

3. Korean Patent Publication No. 2018-0005116 (Double-sided adhesive tape for optical use)

The present invention is intended to solve these problems of the prior art,

First, by combining the function of a decorative film with a double-sided adhesive sheet, the thickness of the laminated structure is minimized,

Second, it is intended to provide an optical double-sided adhesive sheet that can maximize or optimize the folding properties of the display device or input device when the display device or input device is used as a foldable device.

The double-sided adhesive sheet for optical use of the present invention to achieve this purpose may include a first film, a second film, and a double-sided adhesive layer.

The double-sided adhesive layer may be bonded between the first film and the second film. The double-sided adhesive layer may include a transparent base layer, a first adhesive layer, and a second adhesive layer.

One side of the first adhesive layer may be bonded to one side of the transparent base layer and the other side may be bonded to the first film.

One side of the second adhesive layer may be bonded to the other side of the transparent base layer, and the other side may be bonded to the second film.

In the double-sided adhesive sheet for optical use of the present invention, the edge of the double-sided adhesive layer may be positioned inside the edge of at least one of the first and second films.

In the double-sided adhesive sheet for optical use of the present invention, the first and second films may be functional optical films or release films.

In the optical double-sided adhesive sheet of the present invention, the transparent base layer may be a transparent film. In this case, the transparent base layer may have a thickness of 1 to 15 ㎛.

In the optical double-sided adhesive sheet of the present invention, the transparent base layer may be a decor film.

In the optical double-sided adhesive sheet of the present invention, the decoration film may include an overcoat layer and a black matrix layer patterned on one side of the overcoat layer and one side buried in the overcoat layer. In this case, the overcoat layer may have a thickness of 3 to 15 ㎛.

In the optical double-sided adhesive sheet of the present invention, when the black matrix layer is combined, the overcoat layer may include a step portion having a step difference of 0.5 to 5 μm.

In the optical double-sided adhesive sheet of the present invention, the overcoat layer may include an inclined portion having an inclination angle of 30 to 65 ° in the step area.

In the optical double-sided adhesive sheet of the present invention, the first and second adhesive layers bonded to the decor film may have a thickness of 5 to 50 ㎛.

In the optical double-sided adhesive sheet of the present invention, the first and second adhesive layers bonded to the decor film may have a glass transition temperature of -75 to -50 ° C.

The double-sided adhesive sheet for optics of the present invention may include a protective layer bonded between one side of the overcoat layer and the other side of the black matrix layer and the second adhesive layer.

In the optical double-sided adhesive sheet of the present invention, a separation layer bonded between the protective layer and the second adhesive layer may be included.

The double-sided adhesive sheet for optical use of the present invention having such a structure can minimize the thickness of the laminated structure by embedding a black matrix layer in the double-sided adhesive layer, and further facilitate the design of the laminated structure.

The optical double-sided adhesive sheet of the present invention can effectively block or minimize contamination of the double-sided adhesive layer by forming the width of the double-sided adhesive layer to be smaller than the first and second films.

In addition, the double-sided adhesive sheet for optical use of the present invention, when the transparent base layer is composed of a decoration film, has good folding properties even at a curvature radius of 2 mm (2R) by optimizing the thickness of the transparent base layer and the first and second adhesive layers. can be provided.

1 is a cross-sectional view of a double-sided adhesive sheet for optical use according to a first embodiment of the present invention.
Figures 2a and 2b are cross-sectional views showing an example in which the transparent base layer is composed of a decor film in the double-sided adhesive sheet for optical use according to the present invention.
Figure 3 is a cross-sectional view of a double-sided adhesive sheet for optical use according to a second embodiment of the present invention.
Figure 4 is a cross-sectional view of a double-sided adhesive sheet for optics of a third embodiment according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a double-sided adhesive sheet for optics of a first embodiment according to the present invention.

As shown in FIG. 1, the optical double-sided adhesive sheet of the first embodiment may include a first film 310, a second film 320, and a double-sided adhesive layer (110, 210, 220).

The first film 310 may be a functional optical film, a release film, or the like.

Functional optical films may include protective films for various purposes, such as reflective films, diffusion films, prism films, transparent films, polarizing films, moisture-proof films, touch sensor films, antenna films, etc.

The release film may include protective release paper, etc.

The second film 320, similar to the first film 310, may be a functional optical film, a release film, or the like.

The double-sided adhesive layers (110, 210, 220) are bonded between the first film 310 and the second film 320, and are used to attach the transparent base layer 110, the first adhesive layer 210, the second adhesive layer 220, etc. It can be included.

The transparent base layer 110 is bonded between the first adhesive layer 210 and the second adhesive layer 220, and can simply be composed of a single transparent film. Transparent films include polyethyleneetherphthalate, polyethylenenaphthalate, polycarbonate, polyarylate, polyetherimide, polyethersulfonate, polyimide, Polyethertherketone, Polyethylene Terephthalate, Triacetyl Cellulose, Cyclo-olefin Polymer, Aramide, FRP, polyurethane , at least one selected from the group consisting of polyacrylate and polydimethylsiloxane may be used.

When composed of a single transparent film, the transparent base layer 110 may have a thickness of 1 to 15 ㎛.

One side of the first adhesive layer 210 may be bonded to one side (top surface in FIG. 1) of the transparent base layer 110, and the other side (top surface in FIG. 1) may be bonded to the first film 310. .

The first adhesive layer 210 may include urethane oligomer, diluted monomer, photoinitiator, etc.

The urethane oligomer has one or more skeletons selected from the group consisting of polyethylene, polypropylene, polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, polyester, and polyether, and has a radical polymerizable functional group at at least one end. You can.

For example, the urethane oligomer can be prepared by reacting polyol, diisocyanate, and a radically polymerizable compound having a hydroxy group. In addition to the radically polymerizable compounds having the hydroxy group, C ₁ -C ₁₀ alcohol compounds can be additionally used.

The polyol may be a polyolefin, polyester polyol, or polyether polyol having hydroxy groups at both ends, and especially may be polyester polyol. When polyester polyol is used, it is preferable in terms of folding properties, especially at low temperatures, and adhesion to various substrates.

The diisocyanate compound may be an aliphatic diisocyanate compound and/or an aromatic diisocyanate compound.

As the radically polymerizable compound having the hydroxy group, a (meth)acrylate compound containing a hydroxy group can be used.

The diluting monomer may include (meth)acrylate having an alkyl group of C ₆ -C ₃₀ and a (meth)acrylic monomer having a polar functional group. The (meth)acrylic monomer having a polar functional group may be included in an amount of 3 to 30% by weight based on 100% by weight of the total diluted monomer.

The (meth)acrylate having an alkyl group of C ₆ -C ₃₀ has a low glass transition temperature (Tg) and can lower the storage modulus after curing of the adhesive composition, thereby improving folding properties.

The (meth)acrylic monomer having the polar functional group can form a hydrogen bond or ionic bond with the polar group of the lower substrate, thereby improving the adhesion of the adhesive composition.

The (meth)acrylic monomer having the polar functional group may be one or more of (meth)acrylate having a hydroxy group and (meth)acrylamide having a nitrogen atom.

The mixing ratio of urethane oligomer and diluted monomer may be 1:9 to 5:5 by weight.

The photoinitiator may be contained in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the total amount of urethane oligomer and diluted monomer.

The first adhesive layer 210 may have a glass transition temperature of -75 to -50°C. As the first adhesive layer 130 has a glass transition temperature in the above range, it is easy to secure folding properties.

The first adhesive layer 210 may have a thickness of 5 to 50 ㎛, and by having a thickness within the above range, reliability and folding properties can be secured.

One side (upper side in FIG. 1) of the second adhesive layer 220 is bonded to the other side (lower side in FIG. 1) of the transparent base layer 110. The other side (lower surface in FIG. 1) may be coupled to the second film 320.

The second adhesive layer 220 may be made of the same material as the first adhesive layer 210 described above.

The second adhesive layer 220 may have a thickness of 5 to 50 ㎛, similar to the first adhesive layer 210, but does not necessarily have to have the same thickness as the first adhesive layer 210.

The second adhesive layer 220, like the first adhesive layer 210, may have a glass transition temperature of -75 to -50°C. Since the second adhesive layer 140 has a glass transition temperature in the above range, it is easy to secure folding properties.

In the first embodiment of Figure 1, the edges of the double-sided adhesive layers (110, 21, 220) are located inside the edges of the first and second films (310, 320), which effectively prevents contamination of the double-sided adhesive layers during storage or use. It can be blocked or minimized.

Figures 2a and 2b are cross-sectional views showing an example in which the transparent base layer is composed of a decor film in the double-sided adhesive sheet for optical use according to the present invention.

As shown in FIG. 2A, the transparent base layer 110 may be composed of a decor film.

The decor film may include an overcoat layer (or planarization layer, hereinafter collectively referred to as an overcoat layer) 111, a black matrix layer 112, etc.

The overcoat layer 111 embeds and supports a portion of the black matrix layer 112, and can perform functions such as level difference correction, flattening, refractive index control, and a protective layer of the black matrix layer 112.

The overcoat layer (or planarization layer) can be composed of an organic film, and in addition, an inorganic film or an organic-inorganic hybrid film can also be used. The organic film can be made of polyacrylate, polyimide, polyester, etc. The inorganic film may be silazane, silica, an inorganic film with secured light transmittance, or a metal film. The inorganic membrane may include an inorganic filler. Inorganic fillers may be spherical nanoparticles that can improve light extraction efficiency. The organic-inorganic hybrid membrane can use dispersed organic-inorganic hybrid complexes such as siloxane and silsesquioxane.

The overcoat layer 111 may have a thickness of 3 ㎛ or more. If the thickness of the overcoat layer 111 is less than 3 ㎛, it may be difficult to cover the black matrix layer 112 even if the black matrix layer 112 is formed to a minimum thickness of 0.5 ㎛. On the other hand, when the overcoat layer 111 is formed with an organic film such as polyacrylate, if the thickness of the overcoat layer 111 exceeds 40㎛, not only does the overall thickness of the double-sided adhesive layer become too thick, but also other layers Even in the unbound state, it is difficult to satisfy the folding property of the 2R condition. Therefore, it may be desirable to maintain the maximum thickness of the overcoat layer 111 at 40 ㎛ or less.

The black matrix layer 112 may be patterned on one side (lower surface in FIG. 2A) of the overcoat layer 111, and one side (upper and side surfaces in FIG. 2A) may be buried in the overcoat layer 111.

The black matrix layer 112 functions as a light blocking layer that blocks light, and may be located in the non-display area of the display device, that is, the bezel area surrounding the display unit.

The black matrix layer 112 may be composed of a single thin film with a single step. The black matrix layer 112 may have a tapered portion in the step area.

The black matrix layer 112 may be made of a black resin composition. The black resin composition may be a composition containing a resin in which black pigment particles are dispersed, a binder resin, a polymerizable compound, a polymerizability initiator, an additive, etc., or a photocurable (thermocurable) resin composition containing black pigment and having a black color. You can.

The black pigment may be carbon black, graphite, metal oxide, etc. The black pigment may include an organic black pigment, which may be aniline black, lactam black, or perylene black.

Additives may include adhesion accelerators, photocrosslinking sensitizers, curing accelerators, surfactants, dispersants, antioxidants, ultraviolet absorbers, thermal polymerization inhibitors, leveling agents, etc., and may include one or more of these.

The black matrix layer 112 may use photolithography to form a thin film.

The black matrix layer 112 can be formed to have an optical density of 5 or more and a thickness of 0.5 to 5 ㎛. If the thickness of the black matrix layer 112 is less than 0.5 ㎛, the light blocking function may not be achieved, and if the thickness exceeds 5 ㎛, the increase in light blocking function is minimal, but this may not be desirable because the increase in thickness reduces folding properties. there is.

In the area where the black matrix layer 112 is formed, a step portion may be formed in the overcoat layer 111. If the black matrix layer 112 is formed to have a thickness of 0.5 to 5 ㎛, a step of 0.5 to 5 ㎛ corresponding to the thickness of the black matrix layer 112 may be formed in the step portion of the overcoat layer 111. Due to this step, an inclined surface having an inclination angle of 30 to 65 degrees may be formed in the step portion of the overcoat layer 111.

In this configuration, that is, an optical double-sided adhesive sheet in which the transparent base layer 110 is made of a decoration film, folding properties and high-temperature reliability were evaluated while changing the thickness of the overcoat layer 111 and the first and second adhesive layers 210 and 220. . The folding property was determined by fixing a specimen cut to 20 mm , it was checked whether stripes, breaks, lifting, peeling, etc. occurred in the folding area, and if at least one of these occurred, it was judged as 'X', and if none of these occurred, it was judged as '○'. For high-temperature reliability, the same specimen was stored at high temperature and humidity (temperature 85°C, humidity 85%) for 10 days, and then the occurrence of bubbles was visually checked. If bubbles were generated, it was judged as 'X', and if not, it was judged as '○'.

The first and second adhesive layers (130,140) are isocyanate obtained by reacting 10 parts by weight of isophorone diisocyanate with 81 parts by weight of polycaprolactone diol (manufactured by Daicel Chemical Co., Ltd., product name: Placcel212) having a number average molecular weight of 1230. 40 parts by weight of a urethane oligomer with a weight average molecular weight of 60,000 obtained by reacting 9 parts by weight of 2-hydroxyethyl acrylate with a polymer; 50 parts by weight of 2-ethylhexyl acrylate; It was formed using an adhesive composition prepared by mixing 10 parts by weight of 4-hydroxybutylacrylate and 1 part by weight of Igacure 184 (BASF).

Table 1 below shows the results of folding properties and high temperature reliability measured while the thickness of the first and second adhesive layers 210 and 220 was set to 5㎛ and the thickness of the overcoat layer 111 was increased from 3㎛ to 3㎛ in increments.

1st and 2nd adhesive layer thickness
(㎛) Overcoat layer thickness
(㎛) Folding high temperature reliability 5 3 ○ ○ 6 ○ ○ 9 ○ ○ 12 ○ ○ 15 ○ ○ 18 ○ ○ 21 ○ ○ 24 ○ ○ 27 X ○ 30 X ○ 33 X ○ 36 X ○ 39 X ○

Table 2 below shows the results of folding properties and high temperature reliability measured while the thickness of the first and second adhesive layers 210 and 220 was set to 50 ㎛ and the thickness of the overcoat layer 111 was increased from 3 ㎛ to 3 ㎛ in increments.

1st and 2nd adhesive layer thickness
(㎛) Overcoat layer thickness
(㎛) Folding High temperature reliability 50 3 ○ ○ 6 ○ ○ 9 ○ ○ 12 ○ ○ 15 ○ ○ 18 X ○ 21 X ○ 24 X ○ 27 X ○ 30 X ○ 33 X ○ 36 X ○ 39 X ○

As shown in Tables 1 and 2 above, when the thickness range of the first and second adhesive layers 210 and 220 is set to 5 to 50 ㎛, the thickness of the overcoat layer 111 that satisfies both foldability and high temperature reliability is 15 ㎛ or less. It can be confirmed that, considering the minimum thickness of 3 ㎛, it can be seen that the thickness of the overcoat layer 111 is preferably 3 to 15 ㎛.

As shown in Figure 2b, in the double-sided adhesive sheet for optical use, the transparent base layer 110 further includes a protective layer 113, a separation layer 114, etc. in addition to an overcoat layer 111 and a black matrix layer 112. It can be included.

The protective layer 113 may be bonded to one side (lower surface in FIG. 2B) of the overcoat layer 111 and the other side (lower surface in FIG. 2B) of the black matrix layer 112.

The protective layer 113 can prevent contamination of the black matrix layer 112 and prevent or minimize damage to the black matrix layer 112 during the manufacturing process.

The protective layer 113 may be formed of an organic film containing a polymer having at least one of a hydroxyl group, a carboxyl group, and an amide group.

The separation layer 114 may be coupled to the lower surface of the protective layer 113.

The separation layer 114 supports and protects the protective layer 113 and the black matrix layer 112, and can be separated from the protective layer 113 or the carrier substrate when manufactured by a transfer method.

The separation layer 114 may be composed of a polymer organic film, which includes polyimide polymer, polyvinyl alcohol polymer, polyamic acid polymer, and polyamide ( polyamide)-based polymer, polyethylene-based polymer, polystylene-based polymer, polynorbornene-based polymer, phenylmaleimide copolymer-based polymer, polyazobenzene-based polymer, poly Phenylenephthalamide-based polymer, polyester-based polymer, polymethyl methacrylate-based polymer, polyarylate-based polymer, cinnamate-based polymer, coumarin )-based polymers, phthalimidine-based polymers, chalcone-based polymers, and aromatic acetylene-based polymers.

In the optical double-sided adhesive sheet shown in FIGS. 1, 2a, and 2b, the method of manufacturing the double-sided adhesive layer includes forming a combination of the overcoat layer 111 and the black matrix layer 112, and the first adhesive layer 210. ) and preparing a second adhesive layer 220, and combining the first and second adhesive layers 210 and 220 to the transparent base layer 110, that is, a combination of the overcoat layer 111 and the black matrix layer 112 ( Attachment) may be performed.

The combination of the overcoat layer 111 and the black matrix layer 112 is formed by patterning the black matrix layer 112 on the carrier substrate and then forming the overcoat layer 111 on the black matrix layer 112. can do. Before forming the black matrix layer 112, a separation layer and/or a protective layer may be additionally formed on the carrier substrate.

The first and second adhesive layers 210 and 220 may have release films (release paper) attached to both sides of the first and second adhesive layers 210 and 220.

The step of bonding the first and second adhesive layers 210 and 220 to the transparent base layer 110 involves peeling and removing one of the release films (release paper) attached to both sides of the first and second adhesive layers 210 and 220, and then releasing the first and second adhesive layers 210 and 220. A method of attaching each side from which the film was removed to the transparent base layer 110 can be used.

Figure 3 is a cross-sectional view of a double-sided adhesive sheet for optical use according to a second embodiment of the present invention.

As shown in FIG. 3, the optical double-sided adhesive sheet of the second embodiment can be configured so that the edges of the double-sided adhesive layers (110, 210, 220) are located on the same line as the edges of the first film 310 or the second film 320. there is.

Figure 4 is a cross-sectional view of a double-sided adhesive sheet for optics of a third embodiment according to the present invention.

As shown in FIG. 4, the optical double-sided adhesive sheet of the third embodiment has a configuration in which double-sided adhesive layers (110, 210, 220) are combined between the first and second films (310, 320), and the first film 310 or the second film ( A second double-sided adhesive layer (120, 211, 221) and a third film 330 are additionally laminated on the outer surface of 320) to form a double-sided adhesive sheet for multiple optics. Here, the third film 330 may be a functional optical film, a release film, etc., similar to the first and second films 310 and 320 described above.

The optical double-sided adhesive sheet of the present invention described above can be applied to various display devices including a bezel pattern. Display devices include Plasma Display Panel (PDP), Light Emitting Diode (LED), Organic Light Emitting Diode (OLED), Liquid Crystal Display (LCD), and thin film transistor. There are liquid crystal displays (Thin Film Transistor-Liquid Crystal Display, LCD-TFT), etc.

Above, the present invention has been described through several examples, which are intended to illustrate the present invention. Those skilled in the art will be able to transform or modify this embodiment into other forms. However, since the scope of rights of the present invention is determined by the scope of the patent claims below, such variations or modifications may be interpreted as being included in the scope of rights of the present invention.

110: transparent base layer 111: overcoat layer
112: Black matrix layer 113: Protective layer
114: Separation layer 210: First adhesive layer
220: second adhesive layer 310: first film
320: second film 330: third film

Claims (14)

first film;
second film; and
A first adhesive layer bonded between the first film and the second film, a transparent substrate layer, one side bonded to one side of the transparent substrate layer and the other side bonded to the first film, and one side It includes a double-sided adhesive layer bonded to the other side of the transparent base layer and the other side having a second adhesive layer bonded to the second film,
The transparent base layer is a decor film,
The decor film includes an overcoat layer and a black matrix layer patterned on one side of the overcoat layer and one side buried in the overcoat layer,
The overcoat layer includes a step portion having a step difference of 0.5 to 5 ㎛ and an inclined portion having a 30 to 65 ° inclination angle in the step area. The method of claim 1, wherein the double-sided adhesive layer is
A double-sided adhesive sheet for optical use, the edge of which is located inside the edge of at least one of the first and second films. The method of claim 1, wherein the first and second films are
Double-sided adhesive sheet for optical use, which is a functional optical film or release film. delete The method of claim 1, wherein the transparent base layer is
Double-sided adhesive sheet for optical use, having a thickness of 1 to 15 ㎛. delete delete The method of claim 1, wherein the overcoat layer is
Double-sided adhesive sheet for optical use, having a thickness of 3 to 15 ㎛. delete delete The method of claim 8, wherein the first and second adhesive layers are
Double-sided adhesive sheet for optical use, having a thickness of 5 to 50 ㎛. The method of claim 11, wherein the first and second adhesive layers are
Double-sided adhesive sheet for optical use, with a glass transition temperature of -75 to -50 ℃. According to clause 11,
A double-sided adhesive sheet for optical use, comprising a protective layer bonded between the one side of the overcoat layer, the other side of the black matrix layer, and the second adhesive layer. According to clause 13,
A double-sided adhesive sheet for optical use, comprising a separation layer bonded between the protective layer and the second adhesive layer.

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