KR20210079867A - Adhesion variable adhesive composition for display and Adhesive sheet for display comprising the same - Google Patents

Abstract

The present invention relates to an adhesion-variable adhesive composition for a display and an adhesive sheet for a display including the same. More specifically, the adhesion-variable adhesive composition for a display has a lower adhesive strength before a UV emission or heat energy process to facilitate re-peeling in a process of attaching the adhesive sheet for a display to a display device; facilitates removal of a local part of the adhesive sheet for a display through a laser punching process; provides excellent adhesion to the display device after the UV emission or heat energy process; has a lower flowability of a variable adhesive layer of the adhesive sheet for a display, does not form bubbles during bonding, and has excellent bending performance, thereby being be applied to a display with a step or a flexible display; provides excellent adhesion to the base film; and provides a lower reduction rate of adhesive strength even after leaving in high-temperature and high-humidity conditions. According to the present invention, the adhesion-variable adhesive composition for a display comprises; a (meth)acrylic polymer; (meth)acrylic monomers having an oxyalkylene chain; and a photoinitiator.

Description

Adhesion variable adhesive composition for display and Adhesive sheet for display comprising the same

The present invention relates to a pressure-sensitive adhesive composition for display with variable adhesive strength and an adhesive sheet for display including the same, and more particularly, to a display device with low adhesive strength before UV irradiation or heat energy treatment, so that the adhesive sheet for display is re-peeled in the process of attaching it to a display device. It is easy to use, and it is easy to remove the local part of the adhesive sheet for display through the laser punching process, and after UV irradiation or heat energy treatment, it has excellent adhesion with the display device, and the flowability of the variable adhesive layer of the adhesive sheet for display is easy. It is low, does not generate bubbles during bonding, and at the same time, due to its excellent bending performance, it can be applied to a step display or flexible display as well as has excellent adhesion to the base film, and the rate of decrease in adhesion even after leaving it under high temperature and high humidity conditions It relates to a pressure-sensitive adhesive composition for a display capable of expressing this low effect, and an adhesive sheet for a display comprising the same.

Recently, with the rapid development of information and communication technology and market expansion, a flat panel display is in the spotlight as a display device. As such a flat panel display device, a liquid crystal display device. Plasma display panels, organic light emitting diodes, and the like are representative examples.

The organic light emitting device has advantages such as fast response speed, light and thin, small size, low power consumption, self-luminescence, and flexibility, so the demand for next-generation display devices and flexible displays as well as lighting is increasing.

The organic light emitting device is formed by depositing on a glass substrate in the order of a transparent electrode, a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, an electron injection layer, and a metal electrode, and electrons and holes supplied from both electrodes are recombined in the organic light emitting layer. It is the principle of light emission using the emitted energy.

Since the organic light emitting diode may be deteriorated by external factors such as external moisture, oxygen, or ultraviolet rays, a packaging technology for sealing the organic light emitting diode is important. In order to apply it to various applications, the organic light emitting display device is manufactured to be thin. is required to be

On the other hand, the lower portion of the display device includes an adhesive sheet for protecting the display device from external force. In the process of attaching the adhesive sheet, defects may occur and the adhesive sheet may be removed, but due to the high adhesive strength of the adhesive sheet There may be cases in which it is impossible to remove the adhesive sheet, which makes it difficult to reuse the display device. In addition, due to the high adhesive strength of the adhesive sheet, there was a problem of causing damage to the display device in the local partial removal process through laser punching of the adhesive sheet attached to a large area display device.

Therefore, the adhesive strength of the adhesive sheet is low before UV irradiation or heat energy treatment through the application of variable adhesive properties, so it is easy to re-peel in the process of attaching the adhesive sheet to the display device, and it is easy to remove the local part of the adhesive sheet through the laser punching process After UV irradiation or thermal energy treatment, the adhesive strength with the display device is excellent, the flowability of the variable adhesive layer is low, and bubbles do not occur during bonding, and at the same time, a display or flexible display with a step difference due to excellent bending performance The present invention was completed through research on an adhesive sheet for a display that can be applied to a display, the variable adhesive layer has excellent adhesion to the base film, and can exhibit the effect of a low reduction in adhesive force even after leaving it under high temperature and high humidity conditions. did.

Korea Registered Patent No. 10-0252953 (published on: Feb. 25, 1999)

The present invention was devised in consideration of the above problems, and the adhesive strength before UV irradiation or thermal energy treatment is low, so it is easy to re-peel in the process of attaching the adhesive sheet for a display to a display device, and the adhesive for display through a laser punching process An object of the present invention is to provide a pressure-sensitive adhesive composition for a display capable of easily removing a local portion of a sheet and an adhesive sheet for a display including the same.

In addition, the present invention has excellent adhesion to the display device after UV irradiation or thermal energy treatment, low flowability of the variable adhesive layer of the adhesive sheet for display, no bubbles generated during bonding, and excellent bending performance Accordingly, an object of the present invention is to provide an adhesive composition with variable adhesive strength for a display that can be applied to a display having a step or a flexible display, and an adhesive sheet for a display including the same.

In addition, the present invention provides a variable adhesive composition for a display that has excellent adhesion to the base film of the variable adhesive layer and exhibits an effect of a low reduction rate of adhesive force even after being left under high temperature and high humidity conditions, and a display adhesive sheet comprising the same It is intended to provide

In order to solve the above problems, the adhesive composition for display of the present invention is a (meth)acrylic polymer comprising a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component, and (meth) having an oxyalkylene chain. It may include an acrylic monomer and a photoinitiator.

In a preferred embodiment of the present invention, the (meth)acrylic polymer may include a carboxyl group or a hydroxyl group as a functional group.

In a preferred embodiment of the present invention, the (meth)acrylic monomer may have 1 or more and less than 6 acrylic functional groups.

In a preferred embodiment of the present invention, the (meth)acrylic monomer may include a compound represented by the following formula (1).

[Formula 1]

In Formula 1, A is -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ - or -CH ₂ CH ₂ CH ₂ CH ₂ -, R ₁ and R ₂ are each independently It is a C1-C5 alkyl group, and n is a rational number satisfying 100 to 1000.

In a preferred embodiment of the present invention, the adhesive composition of the present invention may include 5 to 15 parts by weight of a (meth)acrylic monomer and 0.1 to 1 parts by weight of a photoinitiator based on 100 parts by weight of the (meth)acrylic polymer. have.

In a preferred embodiment of the present invention, the adhesive composition of the present invention may further include at least one selected from a crosslinking agent and a solvent.

In a preferred embodiment of the present invention, the adhesive composition of the present invention may contain 0.1 to 10 parts by weight of a crosslinking agent and 10 to 30 parts by weight of a solvent based on 100 parts by weight of the (meth)acrylic polymer.

On the other hand, the adhesive sheet for a display of the present invention may include a variable adhesive layer comprising the aforementioned adhesive composition for display with variable adhesive strength.

In a preferred embodiment of the present invention, the adhesive sheet for a display of the present invention may satisfy the following conditions (1) and (2).

(1) A ≤ 100

In the above condition (1), A is the adhesive force of the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, leaving it at a temperature of 25° C. for 1 hour, and peeling it off at 180° at a rate of 300 mm per minute. (gf/25mm).

(2) 300 ≤ B

In the above condition (2), B is the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, irradiating UV with ^{a light quantity of 300 mJ/cm 2} , and peeling it at 180° at a rate of 300 mm per minute. Adhesion (gf/25mm).

In a preferred embodiment of the present invention, the adhesive sheet for display of the present invention may further include a base film laminated on one surface of the variable adhesive layer.

In a preferred embodiment of the present invention, the base film of the present invention may include an antistatic layer on at least one surface.

Furthermore, the present invention provides a display including the aforementioned adhesive sheet for display.

The adhesive composition for display of the present invention and the adhesive sheet for display including the same have low adhesive strength before UV irradiation or thermal energy treatment, so that re-peelability is easy in the process of attaching the adhesive sheet for display to a display device, and the laser punching process It is easy to remove the local part of the adhesive sheet for display through the

In addition, the adhesive composition for a display of the present invention and the adhesive sheet for a display including the same have excellent adhesive strength with a display device after UV irradiation or heat energy treatment, and the flowability of the variable adhesive layer of the adhesive sheet for a display is low. Also, it does not generate bubbles during bonding and at the same time has excellent bending performance, so it can be applied to a display with a step or a flexible display.

In addition, the adhesive composition for display of the present invention and the adhesive sheet for display including the same have excellent adhesion with the base film of the variable adhesive layer, and exhibit a low rate of decrease in adhesive force even after leaving under high temperature and high humidity conditions. .

1 is a schematic cross-sectional view of a display adhesive sheet of the present invention as a preferred specific embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals are added to the same or similar elements throughout the specification.

The adhesive composition for a display of the present invention includes a (meth)acrylic polymer, a (meth)acrylic monomer, and a photoinitiator.

First, the (meth)acrylic polymer of the present invention is a base material for enabling the adhesiveness variable adhesive composition for a display to have adhesive strength, and may include a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component.

In addition, the (meth)acrylic polymer of the present invention may include a carboxyl group or a hydroxyl group as a functional group.

In addition, the (meth)acrylic polymer of the present invention may contain 30 to 50% of solid content, preferably 35 to 45%, and 1200 to 2000 g/25mm, preferably 1500 to 1700 g/25mm of adhesive strength (180 °, peel strength), the curing agent may be included in an amount of 0.1 to 20% by weight, preferably 0.2 to 10% by weight, based on the total weight%.

In addition, the (meth)acrylic polymer of the present invention may contain 20 to 40% of solid content, preferably 25 to 35%, and 4000 to 10000 mPa·s (30° C.), preferably 6000 to 7500 mPa·s ( 30° C.), and may have a weight average molecular weight of 500,000 to 900,000 g/mol, preferably 600 to 800,000 g/mol.

Next, the (meth)acrylic monomer of the present invention is a material that enables the adhesive composition for display of the present invention to express the adhesive strength variable characteristic function, and the number of acrylic functional groups is 1 or more and less than 6, preferably 1 or more and 3 It may be less than, and preferably may include a compound represented by the following formula (1).

[Formula 1]

In Formula 1, A is -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ - or -CH ₂ CH ₂ CH ₂ CH ₂ -, preferably -CH ₂ - or -CH ₂ CH ₂ - may be.

In addition, in Formula 1, R ₁ and R ₂ may each independently be a C1-C5 alkyl group, preferably a C1-C3 alkyl group.

In addition, in Formula 1, n may be a rational number satisfying 100 to 1000, preferably, a rational number satisfying 300 to 700.

On the other hand, the adhesive composition for a display variable adhesive composition of the present invention, based on 100 parts by weight of the (meth)acrylic polymer, 5 to 15 parts by weight of the (meth)acrylic monomer, preferably 7 to 13 parts by weight, more preferably 9 to 11 parts by weight. It may be included in parts by weight, and if the (meth)acrylic monomer is included in less than 5 parts by weight, there may be a problem in that the adhesive strength is increased before UV irradiation, and if it exceeds 15 parts by weight, the adhesion between the variable adhesive layer and the base film is lowered. There may be a problem in which the variable adhesive layer falls off.

Next, the photoinitiator of the present invention may use a photoinitiator capable of UV photocuring generally used in the art, preferably 1-hydroxycyclohexylphenylketone, 1-hydroxy-2-methyl-1- phenyl-propan-1-one, dimethyl 2,4,6-trimethylbenzoyl phosphine oxide, and 2,2-dimethoxy-2-phenylacetophenone may include at least one selected from the group consisting of, more preferably 2, 2-dimethoxy-2-phenylacetophenone.

In addition, the adhesive composition for a display of the present invention contains 0.1 to 1 parts by weight of a photoinitiator, preferably 0.1 to 0.8 parts by weight, more preferably 0.2 to 0.5 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer. If the photoinitiator contains less than 0.1 parts by weight, there may be a problem of lowering adhesion with the display device due to poor adhesion after UV irradiation, and if it contains more than 1 part by weight, in fluorescent and / or LED lighting lamps. The photoinitiator is decomposed due to the weak amount of UV generated to form a low molecular weight polymer, which may cause a problem in that the desired level of adhesion cannot be reached when irradiated with UV light.

Furthermore, the adhesive composition for display of the present invention may further include at least one selected from a crosslinking agent and a solvent, and preferably further include a crosslinking agent and a solvent.

The crosslinking agent of the present invention may use a crosslinking agent capable of crosslinking various components generally used in the art, and may preferably include a compound having a tetrafunctional epoxy functional group, more preferably the following formula 2 It may include a compound represented by.

[Formula 2]

In Formula 2, B ₁ , B ₂ , B ₃ and B ₄ are each independently -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ - or -CH ₂ CH ₂ CH ₂ CH ₂ -, preferably -CH ₂ - or -CH ₂ CH ₂ -.

In addition, the adhesive composition for display of the present invention may contain 0.1 to 10 parts by weight of a crosslinking agent, preferably 0.5 to 8 parts by weight, more preferably 3 to 6 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer. If the crosslinking agent is included in less than 0.1 parts by weight, the variable adhesive layer may not be cured to the desired level, and as the crosslinking density decreases, the flowability of the variable adhesive layer increases, and bubbles may occur during bonding. Accordingly, the adhesive performance may decrease, and if it exceeds 10 parts by weight, the variable adhesive layer is overcured, and as the gel fraction is saturated, there may be a problem in that the adhesive strength and bending performance decrease, and unreacted crosslinking agent may remain. .

As the solvent of the present invention, various solvents generally used in the art may be used, and preferably, one or more selected from methyl ethyl ketone, toluene, ethyl acetate and tetrahydrofuran (THF) may be included, and more preferably For example, methyl ethyl ketone may be included.

In addition, the adhesive composition for display of the present invention may contain 10 to 30 parts by weight of a solvent, preferably 15 to 25 parts by weight, more preferably 18 to 22 parts by weight based on 100 parts by weight of the (meth)acrylic polymer. If the solvent is included in less than 10 parts by weight, the viscosity is high and there may be a problem in realizing the desired physical properties after adhesion to the desired level due to non-uniform mixing during preparation of the crude liquid, and if it exceeds 30 parts by weight, the viscosity is low and the base When the pressure-sensitive adhesive composition is applied to the film, the pressure-sensitive adhesive composition flows and it can be difficult to produce a thickness of the pressure-sensitive adhesive sheet at the desired level. There may be problems that cause it.

Meanwhile, referring to FIG. 1 , the adhesive sheet for a display of the present invention may include a variable adhesive layer 20 . In addition, the variable adhesive layer 20 may further include a base film 10 laminated on one surface, and may further include a liner film 30 laminated on the other surface of the variable adhesive layer 20 .

The variable adhesive layer 20 of the present invention is configured to exhibit a certain adhesive force by UV irradiation so that the base film 10 can be attached to the lower part of the display device, and includes the aforementioned adhesive variable adhesive composition for display. can do.

The thickness of the variable adhesive layer 20 may be 5 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 20 μm, and if the thickness of the variable adhesive layer 20 is less than 5 μm, There may be a problem in the expression of the desired level of adhesive strength after UV irradiation, and when it exceeds 100 μm, it is not removed cleanly when removing the local part after laser punching of the adhesive sheet, and a part of the variable adhesive layer 20 is attached to the display device. There may be problems in driving the display device.

The base film 10 of the present invention is directly attached to the device for display and serves to protect the lower portion of the device for display. The base film may include without limitation as long as it is a material that can be commonly used as an adhesive sheet in the art, and may preferably include a PET (polyethylene terephthalate) film. In addition, the thickness of the base film 10 is not limited as long as it is the thickness of the base film that can be used as a conventional pressure-sensitive adhesive sheet, preferably 65 to 85 μm, more preferably 70 to 80 μm, but is not limited thereto. does not

The base film 10 may include an antistatic layer 11 on at least one surface to prevent the generation of static electricity, and preferably may include an antistatic layer 11 only on the outer surface of the base film 10 .

Specifically, the base film 10 may include an antistatic layer 11 on the opposite side on which the variable adhesive layer 20 is not laminated, and the antistatic layer 11 is ITO (Indium Tin Oxide), CNT (Carbon Nano). tube), polyaniline, and polythiophene, which may include a material in which a binder is added to a conductive material including at least one of, preferably PEDOT/PSS (poly(3, polythiophene) 4-ethylenedioxythiophene polystyrene sulfonate).

The liner film 30 of the present invention serves to protect the variable adhesive layer 20 and the base film 10 . The adhesive sheet for display is used by being attached to the lower part of the display device in the display device manufacturing process. When the adhesive sheet for display is attached to the lower part of the display device, the liner film 30 is peeled off, and the variable adhesive layer 20 ) is used by attaching one side to the display device.

The liner film 30 may include without limitation as long as it is a material commonly used for a liner film in the art, and may preferably include a PET (polyethylene terephthalate) film. In addition, the thickness of the liner film 30 is not limited as long as the thickness of the liner film 30 that can be used as a conventional pressure-sensitive adhesive sheet is not limited, preferably 15 to 35 μm, more preferably 20 to 30 μm, It is not limited thereto.

The liner film 30 may include a silicone layer 31 on at least one surface to serve to protect the variable adhesive layer 20 , and preferably only a surface in contact with the variable adhesive layer 20 , the silicone layer 31 . ) may be included.

On the other hand, the adhesive sheet for a display of the present invention may satisfy all of the conditions of (1) and (2) below.

(1) A ≤ 100, preferably 1 ≤ A ≤ 50, more preferably 1 ≤ A ≤ 10

In the above condition (1), A is the adhesive force of the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, leaving it at a temperature of 25° C. for 1 hour, and peeling it off at 180° at a rate of 300 mm per minute. (gf/25mm).

(2) 300 ≤ B, preferably 500 ≤ B ≤ 1000, more preferably 600 ≤ B ≤ 800

In the above condition (2), B is the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, irradiating UV with ^{a light quantity of 300 mJ/cm 2} , and peeling it at 180° at a rate of 300 mm per minute. Adhesion (gf/25mm).

Furthermore, the method of manufacturing the adhesive sheet for a display of the present invention may include the first to third steps.

First, the first step of the method of manufacturing the adhesive sheet for a display of the present invention can prepare a pressure-sensitive adhesive composition for a display with variable adhesive strength.

The adhesive composition for display in the first step can be prepared by mixing and stirring (meth)acrylic polymer, (meth)acrylic monomer and photoinitiator, preferably (meth)acrylic polymer, (meth)acrylic monomer and In addition to the photoinitiator, it may be prepared by further mixing a crosslinking agent and a solvent.

At this time, the mixing may be performed in an amount of 5 to 15 parts by weight, preferably 7 to 13 parts by weight, and more preferably 9 to 11 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer, (meth)acrylic monomer, 0.1 to 1 parts by weight of the photoinitiator, preferably 0.1 to 0.8 parts by weight, more preferably 0.2 to 0.5 parts by weight may be mixed, and 0.1 to 10 parts by weight of the crosslinking agent, preferably 0.5 to 8 parts by weight, more preferably may be mixed in 4 to 6 parts by weight, 10 to 30 parts by weight of the solvent, preferably 15 to 25 parts by weight, more preferably 18 to 22 parts by weight.

In addition, the mixing and stirring of the first step may be performed at a temperature of 10 to 40° C., at a temperature of 20 to 30° C. for 10 to 60 minutes, preferably for 20 to 40 minutes.

Next, in the second step of the method for manufacturing the adhesive sheet for display of the present invention, the adhesive composition for display prepared in the first step is applied to the other surface of the base film having an antistatic layer formed on one surface, and the adhesive composition for display prepared in the first step is applied and heated to the other surface of the base film. A variable adhesive layer may be formed. At this time, the heating may be performed at a temperature of 100 to 200 °C, preferably at a temperature of 110 to 150 °C for 1 to 5 minutes, preferably for 1 to 3 minutes.

Finally, in the third step of the method of manufacturing the adhesive sheet for a display of the present invention, a liner film is laminated on one surface of the variable adhesive layer formed in the second step, and the adhesive sheet for display can be manufactured by aging. At this time, the lamination may be performed using a laminator, and the aging may be carried out at a temperature of 30 to 70 ℃, preferably at a temperature of 40 to 60 ℃ for 1 to 5 days, preferably for 1 to 3 days. . In addition, a silicone layer may be formed on the surface of the liner film laminated with the variable adhesive layer.

In the above, the present invention has been mainly described with respect to the embodiment, but this is only an example and does not limit the embodiment of the present invention, and those of ordinary skill in the art to which the embodiment of the present invention pertains can appreciate the essential characteristics of the present invention. It can be seen that various modifications and applications not exemplified above are possible without departing from the scope. For example, each component specifically shown in the embodiment of the present invention can be implemented by modification. And differences related to such modifications and applications should be construed as being included in the scope of the present invention defined in the appended claims.

Example 1: Preparation of adhesive sheet for display

(1) Methyl ethyl ketone as a solvent is first mixed with a (meth)acrylic polymer (Aekyung Chemical, POA-4700, solid content 40%) having a carboxyl group as a functional group, and as a (meth)acrylic monomer represented by the following formula 1-1 A compound (Miwon, Miramer M286), a compound represented by the following formula 2-1 as a crosslinking agent (Mitsubishi Gas Chemical, Tetrad-X), 2,2-dimethoxy-2-phenylacetophenone (IGM, Omnirad-651) as a photoinitiator ) was mixed and stirred at a temperature of 25° C. for 30 minutes to prepare an adhesive composition with variable adhesive strength for display. At this time, mixing was performed with 20 parts by weight of a solvent, 10 parts by weight of a (meth)acrylic monomer, 5 parts by weight of a crosslinking agent, and 0.3 parts by weight of a photoinitiator based on 100 parts by weight of the (meth)acrylic polymer.

[Formula 1-1]

In Formula 1-1, A is -CH ₂ -, R ₁ and R ₂ are a methyl group, and n is 600.

[Formula 2-1]

(2) A PET base film (SKC HT&M, TU63A, thickness: 75㎛) with an antistatic layer on one side is coated with a variable adhesive composition for display on the other side, and heated at a temperature of 130°C for 1 minute to change the other side of the base film An adhesive layer (thickness: 15 µm) was formed.

(3) One side of the variable adhesive layer and one side of a PET liner film (thickness: 25 μm) treated with silicone were laminated using a laminator, and aged at 50° C. for 2 days to prepare an adhesive sheet for display.

Example 2

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M2040) represented by the following Chemical Formula 1-2 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 1-2]

In Formula 1-2, A is -CH ₂ -, R ₁ and R ₂ are a methyl group, and n is 400.

Example 3

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a (meth)acrylic polymer having a hydroxyl group as a functional group, not a (meth)acrylic polymer having a carboxyl group as a functional group (Saiden, X-312-252S, solid content 30%) is used, and iso as a crosslinking agent Hexamethylene diisocyanate containing cyanurate-based modified polyisocyanate (HDI based modified polyisocyanate, containing isocyanurate) (Nippon Polyurethane Kogyo Co., Ltd., Colonate HX) was used, and a crosslinking agent 0.5 based on 100 parts by weight of (meth)acrylic polymer Finally, an adhesive sheet for display was prepared by using parts by weight.

Example 4

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M164) represented by the following Chemical Formula 3 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 3]

Example 5

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, with respect to 100 parts by weight of the (meth)acrylic polymer, 12 parts by weight of the (meth)acrylic monomer was mixed to finally prepare an adhesive sheet for a display.

Example 6

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M2100) represented by the following Chemical Formula 4 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 4]

Example 7

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M2300) represented by the following Chemical Formula 5 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 5]

Comparative Example 1

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M262) represented by the following Chemical Formula 6 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 6]

Comparative Example 2

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, a compound (Miwon, Miramer M121) represented by the following Chemical Formula 7 was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

[Formula 7]

In Formula 7, R ₃ is -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ .

Comparative Example 3

An adhesive sheet for a display was prepared in the same manner as in Example 1. However, unlike Example 1, ethoxylated behenyl methacrylate (Solvay, SIPOMER ^® BEM) was used as a (meth)acrylic monomer to finally prepare an adhesive sheet for a display.

Experimental Example 1

The adhesive sheets for displays prepared in each Example and Comparative Example were evaluated based on the following physical property evaluation method, and the results are shown in Table 1.

(1) Adhesive force of variable adhesive layer (gf/25mm)

The adhesive sheet for display was cut to a size of 25 mm × 200 mm in width, the liner film was removed, and one side of the variable adhesive layer was attached to a polyimide film (thickness: 25 μm) using a 2 kg hand roller at a speed of 3 m/min. . After adhesion, it was left at room temperature (25° C.) for 1 hour, and peeled at a speed of 300 mm per minute at 180° to measure the adhesive force of the variable adhesive layer.

(2) Adhesive force of variable adhesive layer after UV irradiation (gf/25mm)

The adhesive sheet for display was cut to a size of 25 mm × 200 mm in width, the liner film was removed, and one side of the variable adhesive layer was attached to a polyimide film (thickness: 25 μm) using a 2 kg hand roller at a speed of 3 m/min. . After attachment, UV was irradiated in the vertical direction of the base film using a high-pressure mercury lamp, and then peeled at a speed of 300 mm per minute at 180° to measure the adhesive force of the variable adhesive layer.

* UV irradiation conditions *

① Wavelength: 250 ~ 450nm

② Light intensity: 300mJ/cm ²

③ Output: 80mW

(3) Adhesion of the variable adhesive layer with the base film

After removing the liner film of the adhesive sheet for display and cross hatching one side of the variable adhesive layer, the degree of peeling was visually evaluated by rubbing with a finger 5 times with strong force. (Evaluation criteria (Rubbing number): 1 time ~ Peel off 3 times X, peel off 4 to 5 times △, do not peel off more than 5 times ○)

(4) Haze (%), transmittance (%)

Using a hazemeter (NDH7000), the haze and transmittance of the adhesive sheet for a display from which the liner film was peeled were measured, respectively.

(5) Measurement of change rate of adhesive strength of variable adhesive layer after leaving in high temperature and high humidity conditions

Remove the liner film of the adhesive sheet for display, attach one side of the variable adhesive layer to a polyimide film (thickness: 25 μm), and irradiate UV in the vertical direction of the base film using a high-pressure mercury lamp, and then at a temperature of 60° C. And it was left for 500 hours under the conditions of 95% relative humidity. After leaving it sufficiently at room temperature (25° C.), the base film was peeled off at a speed of 300 mm per minute and 180° to measure the adhesive strength of the variable adhesive layer. was measured. When the rate of change of adhesive force satisfies the range of ± 20%, it was denoted by ○, and when it was not satisfied, it was denoted by ×.

* UV irradiation conditions *

① Wavelength: 250 ~ 450nm

② Light intensity: 300mJ/cm ²

③ Output: 80mW

(6) Bending performance evaluation

Remove the liner film of the adhesive sheet for display, attach one side of the variable adhesive layer to a polyimide film (thickness: 25㎛), irradiate UV in the vertical direction of the base film using a high-pressure mercury lamp, and then It was cut to 25 mm x 150 mm. After that, place both ends of the polyimide film to which the adhesive sheet for display is attached to abut, set the radius of curvature to 3R and bend 10000 times, if there is no abnormality ○, in the adhesive sheet for display When any abnormality such as delamination and/or delamination from the adherend surface occurred, the bending performance was evaluated as ×.

* UV irradiation conditions *

① Wavelength: 250 ~ 450nm

② Light intensity: 300mJ/cm ²

③ Output: 80mW

As can be seen in Table 1, the adhesive sheets for displays prepared in Examples 1 to 3 have low adhesive strength before UV irradiation, so it can be confirmed that re-peelability is easy in the process of attaching the adhesive sheet to the display device, and after UV irradiation, It was confirmed that the adhesive strength was excellent, the adhesive strength of the variable adhesive layer with the base film was excellent, and the transmittance was excellent while maintaining a low haze value, the adhesive force change rate was small, and the bending performance was excellent.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

11: antistatic layer
10: base film
20: pressure-sensitive adhesive layer
30: liner film
31: silicon layer

Claims (10)

(meth)acrylic polymer comprising a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component;
(meth)acrylic monomers having an oxyalkylene chain; and
photoinitiator;
Adhesive force variable adhesive composition for display, characterized in that it comprises a.
According to claim 1,
The (meth)acrylic polymer is an adhesive composition for a display, characterized in that it comprises a carboxyl group or a hydroxyl group as a functional group.
According to claim 1,
The (meth)acrylic monomer is an adhesive composition for a display, characterized in that the number of acrylic functional groups is 1 or more and less than 6.
4. The method of claim 3,
The (meth)acrylic monomer is a pressure-sensitive adhesive composition for a display, characterized in that it comprises a compound represented by the following formula (1).
[Formula 1]

In Formula 1, A is -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ - or -CH ₂ CH ₂ CH ₂ CH ₂ -, R ₁ and R ₂ are each independently It is a C1-C5 alkyl group, and n is a rational number satisfying 100 to 1000.
According to claim 1,
The adhesive composition variable adhesive composition for a display, characterized in that it comprises 5 to 15 parts by weight of a (meth)acrylic monomer and 0.1 to 1 parts by weight of a photoinitiator based on 100 parts by weight of the (meth)acrylic polymer.
6. The method of claim 5,
The adhesive composition of the variable adhesive strength for a display, characterized in that it further comprises at least one selected from a crosslinking agent and a solvent.
7. The method of claim 6,
The adhesive composition variable adhesive composition for a display, characterized in that it comprises 0.1 to 10 parts by weight of a crosslinking agent and 10 to 30 parts by weight of a solvent based on 100 parts by weight of the (meth)acrylic polymer.
A variable adhesive layer comprising the adhesive composition for a display according to any one of claims 1 to 7; including,
An adhesive sheet for a display, characterized in that it satisfies the following conditions (1) and (2).
(1) A ≤ 100
(2) 300 ≤ B
In the above condition (1), A is the adhesive force of the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, leaving it at a temperature of 25° C. for 1 hour, and peeling it at 180° at a rate of 300 mm per minute (gf/25mm),
In the above condition (2), B is the variable adhesive layer measured by attaching the adhesive sheet for display to the polyimide film, irradiating UV with ^{a light quantity of 300 mJ/cm 2} Adhesion (gf/25mm).
The method of claim 8, wherein the adhesive sheet for display is
a base film laminated on one surface of the variable adhesive layer;
Adhesive sheet for display, characterized in that it further comprises.
10. The method of claim 9,
The base film is an adhesive sheet for a display, characterized in that it comprises an antistatic layer on at least one surface.

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