KR102661529B1 - Adhesive materials and their use - Google Patents

Abstract

By providing an adhesive material for display adhesive containing a copolymer containing a repeating unit represented by the following formula (1), the effect of having a storage modulus of 1.0*10 ⁴ to 1.0*10 ⁶ Pa at a temperature of -40°C or more and 100°C or less can be provided.
[Formula 1]

Description

Adhesive materials and their use {ADHESIVE MATERIALS AND THEIR USE}

The present invention relates to a photocurable adhesive composition and its use, and more specifically, to a photocurable adhesive that secures elasticity and hardness above a certain level, has excellent flexibility and bending resistance, and has viscoelastic stability against temperature increases and high peel strength. The aim is to provide a composition, an adhesive film for a display using the same, and a method for manufacturing the same.

Optical display devices include display elements including window films, conductive films, and organic light-emitting elements. In an optical display device, various display elements can be adhered to each other using a transparent adhesive film (OCA, optical clear adhesive).

Recently, a flexible optical display device has been developed as an optical display device. Accordingly, the adhesive film must have good reliability by not peeling or generating bubbles due to temperature changes at high, room, or low temperatures or thermal shock, and must have good folding properties.

Adhesive films can be used to adhere window films and adherends in optical display devices. At this time, the entire window film and adhesive film may be folded toward the adhesive film or may be folded toward the window film. When folded toward the window film, the adhesive film is folded in the tension direction, and when folded toward the adhesive film, the adhesive film is folded in the compression direction. Recent flexible displays fold in both directions, so the adhesive film must provide high reliability in both directions.

In addition, the adhesive film must have excellent flexibility at low temperatures and must have excellent resilience and reliability even at high temperatures and/or high humidity. In particular, when increasing the low-temperature flexibility of the adhesive film, it is difficult to secure reliability at high temperatures and/or high humidity. Accordingly, there is a need for an adhesive film that has excellent flexibility at low temperatures while also exhibiting excellent resilience and reliability even at high temperatures and/or high humidity.

Republic of Korea Patent Publication No. 10-2084113

The technical problem to be achieved by the present invention is to provide an adhesive material that has excellent reliability and provides a high storage modulus even at high temperatures.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

In order to achieve the above technical problem, an embodiment of the present invention provides an acrylic adhesive material containing a copolymer containing -A-repeating unit and -B-repeating unit as repeating unit components, wherein A is of the formula below: It is a repeating unit represented by 1, and B is a repeating unit represented by Formula 2 below, a repeating unit represented by Formula 3 below, and a combination thereof.

[Formula 1]

The n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .

[Formula 2]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .

[Formula 3]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ .

At this time, the weight of the copolymer of the repeating unit represented by the following formula (1) may be an acrylic adhesive material, characterized in that it is 1 wt% or more and 5 wt% or less relative to the total weight of the copolymer.

At this time, the adhesive material may be an acrylic adhesive material, characterized in that it has a storage modulus of 1.0*10 ⁴ to 1.0*10 ⁶ Pa at a temperature of -40°C or higher and 100°C or lower.

At this time, the adhesive material may be an acrylic adhesive material, characterized in that it has a glass transition temperature of -55°C or higher and -40°C or lower.

In order to achieve the above technical problem, another embodiment of the present invention provides a mixing step of forming a mixture by mixing a compound represented by Formula 4 below, a compound represented by Formula 5 below, a compound represented by Formula 6 below, and a photoinitiator. ; and an ultraviolet ray irradiation step of irradiating ultraviolet rays to the mixture to which the photoinitiator has been added to proceed with the polymerization reaction.

[Formula 4]

The n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .

[Formula 5]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .

[Formula 6]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ .

In one embodiment of the present invention, the mixing step is performed by adding the compound represented by Formula 4 to the total weight of the compound represented by Formula 4, the compound represented by Formula 5, and the compound represented by Formula 5. It may be a method of manufacturing an acrylic adhesive material, characterized in that it is 1 wt% or more and 5 wt% or less.

According to an embodiment of the present invention, it is possible to provide an adhesive material that has excellent reliability and provides a high storage modulus even at high temperatures.

The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

Figure 1 is a diagram showing a flow chart of the manufacturing method of the acrylic adhesive material.
Figures 2 and 3 are diagrams showing the experimental results of Experimental Example 2.
Figures 4 and 5 are diagrams showing the experimental results of Experimental Example 3.
Figure 6 is a diagram showing the experimental results of Experimental Example 4.
Figure 7 is a diagram summarizing all the experimental results of Experimental Examples 1 to 4.

Hereinafter, the present invention will be described with reference to the attached drawings. However, the present invention may be implemented in various different forms and, therefore, is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts unrelated to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected (connected, contacted, combined)" with another part, this means not only "directly connected" but also "indirectly connected" with another member in between. "Includes cases where it is. In addition, when a part is said to “include” a certain component, this does not mean that other components are excluded, but that other components can be added, unless specifically stated to the contrary.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

As mentioned above, the adhesive film used in flexible or foldable displays must have excellent flexibility at low temperatures and must have excellent resilience and reliability even at high temperatures and/or high humidity. There was a problem that it was difficult to secure reliability at high humidity.

Accordingly, in an embodiment of the present invention, in order to solve the above problem, an acrylic adhesive material containing a copolymer containing -A-repeating unit and -B-repeating unit as repeating unit components, wherein -A - is a repeating unit represented by the following formula (1), and -B- is a repeating unit represented by the following formula (2), a repeating unit represented by the following formula (3), and a combination thereof. An acrylic adhesive material. provides.

[Formula 1]

The n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .

[Formula 2]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .

[Formula 3]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ .

In this specification, “acrylic polymer” refers to a polymer compound formed through a polymerization reaction using a monomer having an acrylic functional group, and “acrylic adhesive material” refers to an adhesive material containing an acrylic polymer. It is done.

The repeating unit represented by Formula 1 is a repeating unit that corresponds to the compound represented by Formula 4 in the acrylic polymer when copolymerized with the compound represented by Formula 4 below as a monomer.

At this time, the compound represented by Formula 4 is a compound that can be prepared by reacting the compounds represented by Formula 4.1 and Formula 4.2 below.

[Formula 4]

[Formula 4.1]

[Formula 4.2]

In the compounds represented by Formula 4, Formula 4.1, and Formula 4.2, n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .

When the compound represented by Formula 4 is mixed with the compound represented by Formula 4.2 and the compound represented by Formula 4.1, S in the compound represented by Formula 4.2 is one side of the acrylate of the compound represented by Formula 4.1. It can be produced by carrying out a [1,4] addition reaction.

The compound represented by Formula 4 has an acrylate functional group, and can undergo polymerization by adding a photoinitiator and irradiating light or adding acid, thereby forming a copolymer containing the repeating unit represented by Formula 1. It becomes possible to synthesize.

In the case of a copolymer containing a repeating unit represented by Formula 1, by using the effect of secondary bond formation due to the ethylene glycol functional group of the repeating unit represented by Formula 1, the polymer containing this has cohesive force and storage modulus. to achieve an improving effect.

In general, acrylic adhesive materials include copolymers and may contain various types of repeating units.

Accordingly, various types of repeating units may be, for example, any one of the repeating unit represented by Formula 2, the repeating unit represented by Formula 3, and combinations thereof, but are not limited to the above examples, and are not limited to the above examples. All repeating units that can be easily adopted by a person skilled in the art should be interpreted as falling within the scope of the present invention:

The repeating unit represented by Formula 2 is a repeating unit corresponding to the compound represented by Formula 5 in the acrylic polymer when copolymerized with the compound represented by Formula 5 below as a monomer.

The repeating unit represented by Formula 3 is a repeating unit corresponding to the compound represented by Formula 6 in the acrylic polymer when copolymerized with the compound represented by Formula 6 below as a monomer.

[Formula 5]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .

[Formula 6]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ .

Hereinafter, the content of the repeating unit represented by Formula 1 contained in the acrylic adhesive material will be described.

As described above, the repeating unit represented by Formula 1 plays a role in increasing the cohesion of the adhesive material, and is preferably present in an amount of 1 wt% or more and 5 wt% or less in the copolymer.

If the content is excessively small (less than 1 wt%), the cohesive strength does not increase sufficiently and cohesive failure occurs, and if the content is excessively large (exceeding 5 wt%), the cohesive strength increases rapidly and the adhesive strength actually decreases. Therefore, it is preferable that the repeating unit represented by Formula 1 is 1 wt% or more and 5 wt% or less.

However, it is not limited to the above numerical range, and the wt% of the repeating unit may vary depending on the type of other repeating units in Formula 1 and the copolymer to be described later, and can be easily changed by those skilled in the art. All possible numerical ranges should be interpreted as falling within the scope of this right.

Below, the characteristics of the acrylic adhesive material will be described.

As can be seen through experimental examples to be described later, the acrylic adhesive materials provided by an embodiment of the present invention have a storage modulus of 1.0*10 ⁴ to 1.0*10 ⁶ Pa at a temperature of -40°C or higher and 100°C or lower. This allows it to be used for flexible display applications and provides excellent reliability while improving the storage modulus at high temperatures.

In addition, the acrylic adhesive materials provided by an embodiment of the present invention may have a glass transition temperature of -55°C or more and -40°C or less, which allows them to be used for flexible display applications and has excellent reliability. It is possible to provide the effect of improving the storage modulus at high temperatures.

In another embodiment of the present invention, in order to solve the above problem, the compound represented by Formula 4, the compound represented by Formula 5, the compound represented by Formula 6, and a photoinitiator are mixed to form a mixture. Step (S100); and an ultraviolet irradiation step (S200) of irradiating ultraviolet rays to the mixture to which the photoinitiator has been added to proceed with the polymerization reaction (S200).

Figure 1 is a diagram showing a flow chart of the manufacturing method of the acrylic adhesive material. Hereinafter, the description will be made with reference to Figure 1.

As can be seen from Figure 1, the manufacturing method provided by an embodiment of the present invention is a two-step process, and can be manufactured through a mixing step (S100) and an ultraviolet irradiation step (S200).

Hereinafter, the mixing step (S100) will be described.

The description of the compound represented by Formula 4 to the compound represented by Formula 6 in this mixing step is replaced with the description of the acrylic adhesive material.

The compound represented by Formula 4 corresponds to a reactant corresponding to the repeating unit represented by Formula 1 in the acrylic adhesive material, and the compound represented by Formula 4 is 1 wt% or more and 5 wt% or less in the mixture. It is preferable, and the detailed description thereof is also replaced with the description for the acrylic adhesive material.

The photoinitiator in the mixing step may be a photoinitiator generally used in photopolymerization, for example, Irgacure184, but is not limited thereto, and is a photoinitiator that can be easily adopted by those skilled in the art. should all be interpreted as falling within the scope of this right.

Hereinafter, the ultraviolet irradiation step (S200) will be described.

In the method for manufacturing the acrylic adhesive material provided by an embodiment of the present invention, the polymerization process is performed using photopolymerization.

In the mixing step (S100), a mixture containing both the reactants and the photoinitiator was formed, and in the ultraviolet irradiation step (S200), by irradiating the mixture with ultraviolet rays, the photoinitiator initiates a radical reaction, resulting in a polymerization reaction of the reactants. leads to .

Hereinafter, the present invention will be described in more detail through preparation examples, comparative examples, and experimental examples. However, the present invention is not limited to the following production examples and experimental examples.

Manufacturing Example 1 - Acrylic adhesive material

In this production example, an acrylic adhesive material was prepared using a compound represented by the following formula (4) and varying the content of the compound to 1 wt%, 3 wt%, and 5 wt%.

[Formula 4]

The n is 2, and R ₁ to R ₃ are all methyl groups.

The specific process is as follows.

After preparing a mixture containing the compound represented by Formula 4, 2-Ethylhexyl acrylate, 2-Hydroxyethyl acrylate, and irgacure184 (photoinitiator), the mixture was irradiated with ultraviolet rays for 10 minutes.

When the reaction was completed, the reaction was terminated and purified to obtain a sample.

In this Preparation Example 1, an acrylic adhesive material could be successfully manufactured through the above process.

Manufacturing Example 2 - Acrylic adhesive material

In this production example, an acrylic adhesive material was prepared using a compound represented by the following formula (4) and varying the content of the compound to 1 wt%, 3 wt%, and 5 wt%.

[Formula 4]

The n is 4, and R ₁ to R ₃ are all methyl groups.

The specific process was carried out in the same manner as Preparation Example 1, except that only n of the compound represented by Chemical Formula 4 was changed from 2 to 4.

In this Preparation Example 2, an acrylic adhesive material was successfully manufactured through the above process.

Experimental Example 1 - Confirmation of glass transition temperature

In this Experimental Example 1, an experiment was conducted to check the glass transition temperature using the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2.

The specific experimental method is as follows.

The glass transition temperature of the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2 was measured using a Differential Scanning Calorimeter (DSC, PerkinElmer, DSC 8000), and the sample was heated to -50°C at a temperature increase rate of 10°C/min. Measurements were made under a nitrogen atmosphere up to ~200°C.

The experimental results of this Experimental Example 1 are summarized in Table 1 below.

Manufacturing example mixing ratio Glass transition temperature (℃) Manufacturing example 1 1wt% -53.05 3wt% -53.96 5wt% -54.04 Manufacturing example 2 1wt% -51.35 3wt% -53.63 5wt% -51.48

As can be seen from the above experimental examples, the glass transition temperatures of the acrylic adhesive materials prepared through Preparation Example 1 and Preparation Example 2 were all lower than -50°C.

Experimental Example 2 - Confirmation of viscoelastic properties

In this Experimental Example 2, an experiment was conducted to confirm the viscoelastic properties of the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2.

Figure 2 is a diagram showing the results of an experiment confirming the storage modulus of an acrylic adhesive material.

Figure 3 is a diagram showing the results of an experiment confirming creep of an acrylic adhesive material.

The specific experimental method of this Experimental Example 2 is as follows.

The viscoelastic behavior of the acrylic adhesive materials prepared in Preparation Example 1 and Preparation Example 2 was analyzed using a rheometer (Anton paar, MCR 102). The measurement sample was coated to a thickness of about 500 μm using a mold, then cured by irradiating 2,000 mJ of UV, and produced in a free-standing form without a support. The manufactured sample was fixed on the rheometer plate under the conditions of strain 0.4% and oscillation frequency 1Hz, and was measured at a constant temperature increase rate of 4℃/min in the temperature range of -40℃~100℃. Creep was also measured using a rheometer (Anton paar, MCR 102). The creep test measured the change in strain of the sample over time by applying a stress of 10,000 Pa to the sample for 10 min. Afterwards, the applied stress was removed and allowed to recover for 10 min.

As can be seen from Figures 2 and 3, the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2 is stored at a temperature of 1.0*10 ⁴ to 1.0*10 ⁶ Pa at a temperature of -40°C or higher and 100°C or lower. It can be seen that it has a small difference in storage modulus between -40℃ and 100℃, showing very stable viscoelastic properties.

Experimental Example 3 - Experiment of resilience

In this Experimental Example 3, an experiment was conducted to check the recovery force using the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2.

Figure 4 is a diagram showing the results of an experiment confirming the recovery ability of an acrylic adhesive material at 100% strain.

Figure 5 is a diagram showing the results of an experiment confirming the recovery ability of an acrylic adhesive material at 400% strain.

The specific experimental method of this Experimental Example 3 is as follows.

The stress relaxation test of the acrylic adhesive material prepared in Preparation Example 1 and Preparation Example 2 was also performed using a rheometer (Anton Paar, MCR 102). The measurement sample was manufactured in the same form as the viscoelasticity measurement sample and was fixed on the rheometer plate. The stress relaxation test measured the change in stress of the sample over time by applying strains of 100%, 200%, 300%, and 400% to the sample for 10 minutes, and then the strain was removed and recovered for 10 minutes. Stress relaxation and recovery characteristics were evaluated through the stress behavior of the sample and strain deformation according to the applied strain, and stress relaxation was calculated using the following equation.

As can be seen from Figures 4 and 5, the acrylic adhesive materials prepared in Preparation Example 1 and Preparation Example 2 have high recovery characteristics due to deformation.

Experimental Example 4 - Optical properties experiment

In this Experimental Example 4, an experiment was conducted to confirm the optical properties of the acrylic adhesive materials prepared in Preparation Example 1 and Preparation Example 2.

Figure 6 is a diagram showing the results of an experiment confirming the optical properties of an acrylic adhesive material.

The specific experimental method of this Experimental Example 4 is as follows.

The optical properties of the acrylic adhesive materials prepared in Preparation Example 1 and Preparation Example 2 were confirmed using a UV-Visible spectrometer (GBC, Cintra 10e). The acrylic adhesive material was uniformly coated on the PET film substrate with a thickness of 50um. The background was set with bare PET film, and the transmittance was measured in the wavelength range of 400-800 nm. The haze of the acrylic adhesive material was evaluated using a hazemeter (Su Co., HZ-V3).

The experimental results of this Experimental Example 4 are summarized in Table 2 below.

Manufacturing example mixing ratio Transmittance
(%) ^One Transmittance
(%) ² Haze
(%) ² Manufacturing Example 1 1wt% 110.2 92.20 1.0 3wt% 110.8 92.44 0.42 5wt% 111.4 92.30 0.73 Manufacturing example 2 1wt% 109.9 91.91 0.79 3wt% 110.1 92.36 0.84 5wt% 111.6 92.60 0.63

1) UV-Vis. Measured by Spectroscopy

2) Measurement with Hazemeter

Figure 7 is a diagram summarizing all the experimental results of Experimental Examples 1 to 4 above.

As can be seen from Experimental Examples 1 to 4, the acrylic adhesive material provided according to an embodiment of the present invention has excellent reliability and can provide a high storage modulus even at high temperatures.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as single may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the patent claims described below, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.

Claims (6)

In the acrylic adhesive material containing a copolymer containing -A-repeating units and -B-repeating units as repeating unit components,
The -A- is a repeating unit represented by the formula 1 below,
The -B- is any one of a repeating unit represented by Formula 2 below, a repeating unit represented by Formula 3 below, and a combination thereof,
An acrylic adhesive material, characterized in that the content of the repeating unit represented by the following formula (1) is 1 wt% or more and 5 wt% or less based on the total weight of the copolymer:
[Formula 1]

The n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .
[Formula 2]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .
[Formula 3]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ .
delete According to paragraph 1,
The adhesive material is an acrylic adhesive material, characterized in that it has a storage modulus of 1.0*10 ⁴ to 1.0*10 ⁶ Pa at a temperature of -40°C or higher and 100°C or lower. According to paragraph 1,
The adhesive material is an acrylic adhesive material, characterized in that it has a glass transition temperature of -55℃ or higher and -40℃ or lower. A mixing step of forming a mixture by mixing a compound represented by Formula 4 below, a compound represented by Formula 5 below, a compound represented by Formula 6 below, and a photoinitiator; and
An ultraviolet irradiation step of conducting a polymerization reaction by irradiating ultraviolet rays to the mixture to which the photoinitiator is added;
Method for manufacturing an acrylic adhesive material, comprising:
[Formula 4]

The n is a natural number of 1 to 10, and R ₁ to R ₃ are each independently an alkyl group of C ₁ to C ₄ .
[Formula 5]

R ₄ is a substituted or unsubstituted chain alkyl group of C ₁ to C ₁₀ .
[Formula 6]

R ₅ is a substituted or unsubstituted chain alkoxy group of C ₁ to C ₅ . According to clause 5,
The mixing step is characterized in that the compound represented by Formula 4 is 1 wt% or more and 5 wt% or less relative to the total weight of the compound represented by Formula 4, the compound represented by Formula 5, and the compound represented by Formula 5. Method for manufacturing an acrylic adhesive material.