KR102024080B1 - Composition for optical adhesive agent curable by ultraviolet, and an adhesive agent prepared from the composition, and a method for preparing the adhesive agent - Google Patents

Abstract

The present invention relates to an ultraviolet curable optical adhesive composition, an adhesive prepared from the composition, and a method for producing the adhesive.

Description

Composition for optical adhesive agent curable by ultraviolet, and an adhesive agent prepared from the composition, and a method for preparing the adhesive agent

The present invention relates to an ultraviolet curable optical adhesive composition, an adhesive, and a method for producing the adhesive.

The touch screen panel generally has a structure in which a transparent electrode and a display module are disposed under a cover window. The touch screen panel initially used an air gap between the cover window and the transparent electrode, but now, a full lamination method (or a direct bonding method) filled with an optical adhesive material is used. } Is becoming common. In this full lamination type touch screen panel structure, the optical adhesive material used for bonding each layer is an optically clear adhesive (OCA) of a transparent double-sided tape type. It is divided into liquid type optically clear resin.

In the adhesive layer of an OCA film for attaching a cover window having a black or white printed step layer and a transparent electrode, the adhesive layer has an inherent elastic property because it has a film shape. Therefore, when the adhesive layer is adhered, different voids occur in the step at the side of the black or white printed step layer, which is a problem that is visually recognized and that the voids move throughout the cover window and cause defects. there is a problem.

The present invention provides a step in the side of a flat or curved cover window black or white printed step layer when a common OCA film is bonded to attach a flat or curved cover window having a black or white printed step layer and a transparent electrode, In the case of the cover window having a curved surface, void generation due to the curved angle becomes large.

Republic of Korea Patent Application Publication No. 10-2013-0051921

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SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and after bonding the adhesive with a flat or curved cover window having a black or white printing stepped layer, the stress relexation of OCA having secondary curing, post curing or additional photocuring characteristics. (Hereinafter referred to as 'SR'), but it is possible to effectively overcome the step of the black or white printed step layer by increasing the adhesion to the curved surface, flat cover window black or white printed step surface by the SR value before UV curing. UV curable optical adhesives that can effectively reduce the generation of permeable voids due to the step difference and prevent the generation of bubbles in the reliability conditions by increasing the cohesion by the SR characteristics after UV curing, manufacture of the adhesive To provide a composition, a method for producing the adhesive.

In one aspect of the present invention, the UV light-curable optical stress range of 0.05% to 0.15% at 70 ℃, the stress relaxation value after UV irradiation in the range of 0.18% or more at 70 ° C measured by UV irradiation with respect to the adhesive Adhesive for is provided:

[Equation 1]

Stress Relaxation (%) = S _300seconds / S _{0 .1seconds} x 100

In the formula 1, S _{0 .1second} is 0.1 seconds was added to the 25% strain at a temperature condition of 70 ℃ of the adhesive film measured modulus values, S _300seconds is an adhesive film 300 seconds at a temperature of 70 ℃ 25% strain The modulus measured after adding.

Another aspect of the invention is an acrylic copolymer in which at least one monomer selected from a low temperature glass transition (meth) acrylic monomer, a high temperature glass transition (meth) acrylic monomer, and a (meth) acryl monomer having a hydrophilic group is partially polymerized; Photoinitiators having a benzophenone structure; Acrylates having an oxetane structure; Cationic photoinitiators; And a photoinitiator having a radiation reactive site that is activated by a longer wavelength of radiation than the photoinitiator having a benzophenone structure.

Another aspect of the present invention is a method for producing an ultraviolet curable optical adhesive,

Acryl partially polymerized by irradiating UV light to a mixture comprising a low temperature glass transition (meth) acrylic monomer, a high temperature glass transition (meth) acrylic monomer, and at least one monomer selected from a (meth) acryl monomer having a hydrophilic group and a photoinitiator Preparing a copolymer;

Radiation responsiveness to the partially polymerized acrylic copolymer, which is activated by longer wavelength radiation than a photoinitiator having a benzophenone structure, a (meth) acrylate having an oxetane structure, a cationic photoinitiator and a photoinitiator having the benzophenone structure Adding and blending a photoinitiator with a site to form an adhesive precursor composition;

Providing the adhesive precursor composition to the surface of the release film,

A method of manufacturing an ultraviolet curable optical adhesive, comprising irradiating the precursor composition with ultraviolet light having a long wavelength capable of activating a photoinitiator having a radiation reactive site activated by the radiation of the long wavelength, thereby forming an ultraviolet curable optical adhesive. To provide.

Another aspect of the invention, the first substrate; Second substrate; And an ultraviolet curable optical adhesive described herein, positioned between the first substrate and the second substrate, wherein the first substrate or the second substrate has a step of 10 to 50 μm in thickness. to provide.

The adhesive according to the present invention, when used to attach a flat or curved cover window with a black or white printed stepped layer and a transparent electrode, can effectively overcome the step of the black or white printed stepped layer and has a permeable bubble due to the side step. ) It can effectively reduce the occurrence and is stable in high temperature and / or high humidity environment for reliability evaluation.

1 is a cross-sectional view of an image display apparatus having a flat cover or a curved cover laminated using an adhesive according to an aspect of the present invention.

Hereinafter, the present invention will be described in more detail. Content not described herein is omitted because it can be sufficiently recognized and inferred by those skilled in the art or similar fields of the present invention.

One aspect of the invention is a partially polymerized acrylic copolymer of at least one monomer selected from a low temperature glass transition (meth) acryl monomer, a high temperature glass transition (meth) acryl monomer, and a (meth) acryl monomer having a hydrophilic group; Photoinitiators having a benzophenone structure; (Meth) acrylates having an oxetane structure; Cationic photoinitiators; And a photoinitiator having a radiation reactive site that is activated by a longer wavelength of radiation than the photoinitiator having a benzophenone structure.

Partially polymerized acrylic copolymer

The partially polymerized acrylic copolymer is irradiated with ultraviolet light in the presence of a photoinitiator at least one monomer selected from a low temperature glass transition (meth) acrylic monomer, a high temperature glass transition (meth) acrylic monomer, and a (meth) acryl monomer having a hydrophilic group. And partially polymerized.

The low temperature glass transition (meth) acryl monomer has a glass transition temperature of its homopolymer in a range of -100 ° C to 40 ° C, or a range of -80 ° C to 30 ° C, or a range of -75 ° C to -20 ° C. ) Acrylate. Examples thereof include benzyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, cyclohexyl (meth) acrylate, iso-decyl (meth) acrylate, n-decyl ( Meth) acrylate, lauryl (meth) acrylate (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl acrylate, n-hexyl acrylate, n- Octyl (methyl) acrylate, and the like, but is not limited thereto.

The high temperature glass transition (meth) acrylic monomer is a (meth) acrylate having a glass transition temperature of its homopolymer in a range of 50 ° C to 180 ° C, or a range of 70 ° C to 170 ° C, or a range of 80 ° C to 160 ° C. Say. Examples thereof may include, but are not limited to, tert-butyl methacrylate, acryloyl morpholine, methyl (meth) acrylate, phenyl (meth) acrylate, isobornyl (meth) acrylate, and the like. .

The weight ratio of the low temperature glass transition (meth) acrylic monomer and the high temperature glass transition (meth) acrylic monomer may range from 2: 8 to 8: 2, or 3: 7 to 7: 3, or 4: 6 to 6: 4. . When the low temperature glass transition (meth) acryl monomer and the high temperature glass transition (meth) acryl monomer are used in the weight ratio, the adhesive force, high temperature reliability, heat resistance and fairness (breakability) are improved.

As the (meth) acryl monomer having a hydrophilic group, a (meth) acryl monomer having a hydrophilic group such as a hydroxy group, a carboxyl group, a urethane group, an amine group, an amide group can be used, and specifically, a (meth) acryl having a hydroxy group in terms of adhesive strength. Monomers can be used. For example, 2-hydroxy ethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8- (Meth) acrylic acid hydroxyalkyl esters, such as hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate, and caprolactone modified 2 -Hydroxyethyl (meth) acrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, 2-hydroxypropyl (meth) acrylate, 2-hydroxy Butyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth Secondary hydroxyl group-containing monomers such as acrylate; Tertiary hydroxyl group containing monomers, such as 2, 2- dimethyl- 2-hydroxyethyl (meth) acrylate, etc. are mentioned.

In an embodiment, the partially polymerized (meth) acrylic copolymer comprises monomers comprising both low temperature glass transition (meth) acrylic monomers, high temperature glass transition (meth) acrylic monomers, and (meth) acrylic monomers having a hydrophilic group, a photoinitiator. It can be obtained by partially polymerizing by ultraviolet irradiation in the presence of. At this time, the polymerization weight ratio of the low temperature glass transition (meth) acrylic monomer, the high temperature glass transition (meth) acrylic monomer, and the (meth) acryl monomer having a hydrophilic group is 20 to 50:20 to 50: 1 to 20, specifically 30 to 30 50: 30 ~ 50: 5 ~ 15 can be.

Photoinitiators that can be used to prepare partially polymerized acrylic copolymers are materials capable of initiating polymerization by ultraviolet light having a long wavelength (e.g., wavelengths greater than 380 nm) to enable partial polymerization, for example, 1- [4 -(2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,6-di Methylbenzoyl diphenylphosphine oxide, benzoyl diethoxyphosphine oxide, benzoin alkyl ether (benzoin isopropyl ether, benzoylethyl ether, benzoin isobutyl ether, n-butyl benzoin ether, etc.), 1- (4- Isopropylphenyl) -2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl, acetophenone, thioxanthone, camphorquinone, 3 -Ketocoumarin, acenaphthene, 4,4'-dimethoxybenzyl, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2- Butyl-1- [4- (methylthio) phenyl] -2-morpholino-1-one, 2,2-dimethoxy-2-phenyl acetophenone.

The photoinitiator may be used in the range of about 0.05 part by weight to about 5 parts by weight, specifically about 0.1 part by weight to about 1 part by weight, based on 100 parts by weight of the monomer mixture.

Examples of diluents that can be used to prepare partially polymerized acrylic copolymers can be diluted further including monomers, and examples of monomers that can be added include monomers having a linear structure, monomers having a cyclic structure, meta The monomer which has a structure, the monomer which has an acrylonitrile structure, the monomer which has a vinyl acetate structure, etc. are mentioned.

Examples of molecular weight modifiers that can be used to prepare partially polymerized acrylic copolymers include mercaptopropionate, dodecyl mercaptan; Mercaptoacetate, triobisbenzenetriol, α-methylstyrene dimer; Quinones such as o-benzoquinone, m-benzoquinone; Nitrobenzene; Diphenylamine; Butyl catechol; 1,1-diphenyl ethylene etc. are mentioned. -

Benzophenone  Having structure Photoinitiator

The ultraviolet curable optical adhesive composition according to the present invention may include a photoinitiator having a benzophenone structure as the photoinitiator. Since the photoinitiator having a benzophenone structure is activated by the short wavelength radiation, when the short wavelength radiation is irradiated to the adhesive sheet formed from the adhesive composition for ultraviolet curable optics, crosslinking may proceed to obtain a cured adhesive. The use of a photoinitiator having a benzophenone structure is advantageous in that crosslinking is formed by activation of the photoinitiator by short-wave radiation at the time of additional curing or secondary curing or post-curing, thereby increasing the stress relexation value.

The short wavelength radiation may be, for example, radiation of a wavelength less than 380 nm, for example from 200 nm to 365 nm.

When the ultraviolet curable optical adhesive composition is irradiated with long wavelength radiation to form an adhesive sheet, the sheet is placed between the first substrate and the second substrate, heat and / or pressure is applied, and then the short wavelength radiation is irradiated. Photoinitiators having a benzophenone structure are activated to allow further crosslinking.

Examples of the photoinitiator having a benzophenone structure include acryloyl benzophenone, benzophenone, dichlorobenzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, and the like.

The photoinitiator having a benzophenone structure may be included in an amount of 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, based on 100 parts by weight of the partially polymerized (meth) acryl copolymer.

Oxetane  Having a structure ( MET ) With acrylate Cationic Photoinitiator

The ultraviolet curable optical adhesive composition according to the present invention may include a (meth) acrylate having an oxetane structure and a cationic photoinitiator.

Cationic photoinitiator may be used an initiator capable of inducing an ion curing reaction by UV of a wavelength of 280nm or less. At this time, the oxetane structure of the ion-reactive (meth) acrylate is ring-opened so that crosslinking may proceed to obtain a cured adhesive.

When (meth) acrylate having a oxetane structure and a cationic photoinitiator are used, crosslinking is formed by activation of a photoinitiator by short wavelength radiation during additional curing or secondary curing or post-curing, resulting in an increase in stress relexation value. It is advantageous. An example of (meth) acrylate having an oxetane structure that can be used is glycidyl (meth) acrylate.

Examples of cationic photoinitiators that can be used include 4-methylphenyl, 4- (2-methylpropyl) phenyl (4- (2-methylpropyl) phenyl), hexafluorophosphate, triarylsulfonium salts ( triarylsulphonium salts, propylene carbonate, and Igacure 250 (BASF).

Benzophenone  Having structure Photoinitiator  With reactive sites activated by longer wavelength radiation Photoinitiator

In addition to the photoinitiator having a benzophenone structure, the ultraviolet curable optical adhesive composition according to the present invention is activated by radiation having a longer wavelength (for example, a wavelength of 380 nm or more, specifically, a wavelength of 390 nm or more), more than a photoinitiator having a benzophenone structure. And photoinitiators having radiation reactive sites.

Examples of such photoinitiators include 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2,4,6-trimethylbenzoyl di Phenylphosphine oxide, 2,6-dimethylbenzoyl diphenylphosphine oxide, benzoyl diethoxyphosphine oxide, benzoin alkyl ether (benzoin isopropyl ether, benzoylethyl ether, benzoin isobutyl ether, n-butyl benzo Phosphorus ethers, etc.), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl, aceto Phenone, thioxanthone, camphorquinone, 3-ketocoumarin, acenaphthene, 4,4'-dimethoxybenzyl, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methyl Thio) phenyl] -2-morpholinopropan-1-one etc. are mentioned.

The photoinitiator may be included in 0.001 to 10 parts by weight, or 0.01 to 5 parts by weight based on 100 parts by weight of the partially polymerized (meth) acryl copolymer.

The ultraviolet curable optical adhesive composition according to the present invention may further include a filler or an antioxidant, in addition to the above components.

UV Curing Optical Adhesives

Another aspect of the present invention relates to a method for producing an ultraviolet curable optical adhesive,

Preparing a partially polymerized acrylic copolymer by irradiating ultraviolet light to a mixture comprising a low temperature glass transition acrylic monomer, a high temperature glass transition acrylic monomer, and a photoinitiator and at least one monomer selected from acrylic monomers having a hydrophilic group;

Reactivity activated by the radiation having a longer wavelength than the photoinitiator having a benzophenone structure, the (meth) acrylate having an oxetane structure, the cationic photoinitiator, and the photoinitiator having the benzophenone structure, to the partially polymerized acrylic copolymer. Adding and blending a photoinitiator with a site to form an adhesive precursor composition;

Providing the adhesive precursor composition to the surface of the release film,

A method of manufacturing an ultraviolet curable optical adhesive, comprising irradiating the precursor composition with ultraviolet light having a long wavelength capable of activating a photoinitiator having a radiation reactive site activated by the radiation of the long wavelength, thereby forming an ultraviolet curable optical adhesive. To provide.

The detailed description of the above aspect is the same as in the above-mentioned aspect.

That is, the ultraviolet curing optical adhesive is a partially polymerized acrylic of at least one monomer selected from the above-mentioned low temperature glass transition (meth) acrylic monomer, high temperature glass transition (meth) acrylic monomer, and (meth) acryl monomer having a hydrophilic group. Copolymers; Photoinitiators having a benzophenone structure; (Meth) acrylates having an oxetane structure; Cationic photoinitiators; And a photoinitiator having a reactive site activated by radiation having a longer wavelength than the photoinitiator having a benzophenone structure, and mixing the composition for adhesives for ultraviolet curing optics, and using the solution casting, extrusion or the like to release the mixture film. Apply to the surface of the. The adhesive sheet may have a release film, such as a polyester film or polyethylene film, on one or both surfaces thereof.

Thereafter, the pressure-sensitive adhesive sheet may be formed by irradiating long-wavelength radiation capable of activating a photoinitiator having a radiation-reactive site activated by long-wavelength radiation.

The radiation wavelength of the long wavelength ranges from 380 nm to 500 nm.

The thickness of the adhesive layer except for the release film in the adhesive may range from about 50 μm to about 300 μm, specifically from about 100 μm to about 200 μm, more specifically from about 120 μm to about 170 μm.

In another aspect of the present invention, there is provided an ultraviolet curable optical adhesive prepared according to the above aspect.

The ultraviolet curable optical adhesive according to the above aspect, the stress relaxation value measured by the formula 1 before the ultraviolet irradiation is 0.05% to 0.15% or less at 70 ℃, the stress relaxation value after ultraviolet irradiation is characterized in that 0.18% or more at 70 ℃. do:

[Equation 1]

Stress Relaxation (%) = S _300seconds / S _{0 .1seconds} x 100

In the formula 1, S _{0 .1second} is a modulus value, measured after applying a 25% Strain 0.1 seconds at a temperature condition of 70 ℃ adhesives, _300seconds S is added to 25% Strain at a temperature condition of 70 ℃ 300 seconds adhesive The modulus value measured afterwards.

Stress relaxation values of 0.05% to 0.15% or less at 70 ° C are associated with high adhesion to black or white printed stepped surfaces of curved or flat cover windows and also to suppress permeable bubbles, and stress relaxation values after irradiation of 0.18 More than% is related to the suppression of the reliability bubble. The stress relaxation value measured by Equation 1 may be specifically 0.15% or less, more specifically 0.13% or less, 0.05% or more, and more specifically 0.06% or more. The stress relaxation value after UV irradiation may be specifically 0.20% to 0.40%, more specifically 0.21% to 0.30%.

As used herein, the term 'permeable bubble' refers to a bubble located at the outermost portion between Glass and an ultraviolet curable adhesive (OCA), and the measuring method is as follows: UV curable adhesive laminated with a light release film and a heavy release film. After removing the light release film side of the film, roll laminating one side of the PET film without silicone release treatment (applied pressure: 5 ~ 7kgf, application rate: 50 ~ 80mm / sec, application temperature: 20 ~ 25 ℃) After removing the other side of the UV curable adhesive (heavy release film) and laminating it on one side of the slide glass through vacuum lamination (application pressure: 0.01 ~ 0.02Mpa, application time: 5 ~ 7sec, vacuum pressure: 20 Pa, application temperature) : 20 ~ 25 ℃). Autoclave the applied sample (Applied pressure: 5 ~ 8bar, Applied time: 10 ~ 20min, Applied temperature: 40 ~ 60 ℃), and then observe the air bubbles at the extreme side of the slide glass through the optical microscope Measure the distance to.

In this invention, permeable bubble can be suppressed by making SR before ultraviolet irradiation become 0.05% or more. Suppression of the permeable bubble means that the distance from the most extreme side of the permeable bubble present in the most extreme region between the second substrate or the first substrate and the adhesive is less than 0.6 mm.

Another aspect of the invention, the first substrate; Second substrate; And an ultraviolet curable optical adhesive as described herein, positioned between the first substrate and the second substrate, wherein the first substrate or the second substrate has a step of 10 to 50 μm in thickness. do.

UV-curable optical adhesive Lamination

Placing an ultraviolet curable optical adhesive sheet between the first substrate and the second substrate, applying heat and / or pressure, and irradiating short wavelength radiation activates the photoinitiator and cationic photoinitiator having a benzophenone structure to further crosslink. Can be.

The first substrate was placed on one side of the ultraviolet curable optical adhesive sheet, laminated at a speed of 40 mm / sec to 100 mm / sec at a pressure of 2 to 9 kgf and a temperature of 20 ° C. to 30 ° C., and then the second substrate was It can be placed on the other side of the ultraviolet curable optical adhesive sheet, and can be laminated for 1 second to 10 seconds under a vacuum pressure of 30 Pa or less at a pressure of 0.01 to 0.05 Mpa and a temperature of 20 ° C to 30 ° C. After that, the manufactured paper can be removed using the autoclave equipment (applied pressure: 5 ~ 8bar, application time: 10 ~ 20min, application temperature: 40 ~ 60 ℃) bubbles generated during assembly. After bubble removal, ultraviolet-ray may be irradiated and post-curing or secondary hardening may be performed.

At least one of the first substrate and the second substrate has a step such as a step such as a black or white printed step layer or a step on the side of a curved surface. In one example, the second substrate may be a surface protective layer having a step such as a step such as a black or white printed step layer or a step of a side surface of a curved surface, and the first substrate may be an image display module or a touch panel. The step height may be about 10 to about 50 μm, or about 10 to about 40 μm.

The surface protective layer is disposed on the outermost surface of the image display module or touch panel to function to protect it from the external environment. The surface protective layer may be a cover window.

Examples of the image display module may include a liquid crystal display module, a plasma display unit, an organic light emitting diode, an electroluminescent display, and the like.

The touch panel may be an input device that presses a screen with a user's finger or a pen and recognizes the touched position and transmits the touched position to the system. Specifically, the touch panel may use a resistive film, surface acoustic wave (SAW), infrared light, optical type, or the like.

At least one of the first substrate or the second substrate is at least partially transparent so that short wavelength radiation can be applied through it.

Herein, the radiation may use UV or visible light, and when UV radiation is used, an irradiator using a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, an LED, and the like as a light source may be used. In the ultraviolet irradiation, the wavelength may be irradiated to include not only short wavelength but also long wavelength at 200 nm to 450 nm. The ultraviolet irradiation amount is 1000 mJ to 5000 mJ.

Referring to FIG. 1, an image display apparatus having a laminated flat cover (left side of FIG. 1) or a curved cover (right side of FIG. 1) will be described. The image display apparatuses 100 and 101 may have a stepped portion 8. And adhesive layers 60 and 60 'positioned between the surface protection layers 70 and 70' having the film display module and the image display module or the touch panel 80 and 80 '.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, this is presented as a preferred example of the present invention and in no sense can be construed as limiting the present invention.

Example 1

An acrylic copolymer was synthesized using an acrylate monomer capable of ultraviolet polymerization. Low temperature glass transition acrylate monomer (2EHA (2-ethyl hexyl acrylate), homopolymer Tg: -70 ℃, 45.0 wt%, LA (Lauryl acrylate), homopolymer Tg: -26 ℃, 5.0 wt%), high temperature glass transition acrylate Monomer (IBOA (Isobornyl acrylate), homopolymer Tg: 90 ~ 100 ℃, 37.0 wt%, IBOMA (Isobornyl metha acrylate, homopolymer Tg: 170 ℃, 2.0 wt%), acrylate monomer having hydroxyl group (2HEA (2-hydroxyethyl acrylate) ) 9.0 wt%), a mixture of acryloyl morpholine monomer (4-acyloyl morpholine, 2.0 wt%), photoinitiator (Irgacure 184d 0.025 wt%), molecular weight modifier (mercaptopropionate 0.045 wt%) was prepared and 20 minutes Nitrogen purging was carried out, followed by UV irradiation (wavelength: 370 nm, irradiation amount: 2700 mJ) at 25 ° C. to allow the reaction to proceed to 60 ° C.

When the reaction was completed up to 60 ℃ to cool the temperature of the reaction to 30 ℃ and the acrylic copolymer to have a concentration of 25% mass, to prepare a partially polymerized acrylic copolymer syrup.

0.05 parts by weight of Irgacure 184D, 0.05 parts by weight of Igacure 651, 0.05 parts by weight of TPO, 0.3 parts by weight of Irgacure 250, 0.5 parts by weight of benzophenone, and glycidyl methacrylate (GMA) based on 100 parts by weight of the acrylic copolymer syrup ) Was added in a proportion of 0.5 parts by weight and stirred to prepare an ultraviolet curable optical adhesive composition.

The gap of the knife coater was adjusted to 150 μm, and the composition was coated on a 75 μm-thick heavy release film (SKC Hass) release surface, and a light release film was laminated and passed through a UV irradiation device, followed by UV irradiation (wavelength: 380 nm or more, Irradiation amount: 2700mJ).

UV irradiation was performed by inserting a UV cut film that can block the wavelength less than 380nm at the top of the light release film during UV irradiation. As a result, a 150-micrometer-thick ultraviolet curable optical adhesive sheet was obtained.

Example 2

Partially polymerized acrylic copolymer as in Example 1, except that each monomer was used in a weight ratio of 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/3/37/2/11/2 Was carried out in the same manner as in Example 1 to prepare an ultraviolet curable optical adhesive sheet of Example 2.

Example 3

Partially polymerized acrylic copolymer as in Example 1, except that each monomer was used in a weight ratio of 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 43/3/37/2/13/2 Was carried out in the same manner as in Example 1 to prepare an ultraviolet curable optical adhesive sheet of Example 3.

Example 4

Partially polymerized acrylic copolymer as in Example 1, except that each monomer was used in a weight ratio of 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 42/5/40/2/9/2 Was carried out in the same manner as in Example 1 to prepare an ultraviolet curable optical adhesive sheet of Example 4.

Example 5

A partially polymerized acrylic copolymer as in Example 1, except that each monomer was used in a weight ratio of 2EHA / IBOA / 2HEA / ACMO = 46/43/9/2 It carried out by the above and manufactured the ultraviolet curable optical adhesive sheet of Example 5.

Example 6

The partially polymerized acrylic copolymer according to Example 1, wherein each monomer was used at a weight ratio of 2EHA / LA / IBOA / IBOMA / 2HEA / 4HBA / ACMO = 45/5/37/2/7/2/2 Except for the ultraviolet curable optical adhesive sheet of Example 6 was prepared in the same manner as in Example 1.

Example 7

The partially copolymerized acrylic copolymer according to Example 1, wherein each monomer is

The ultraviolet curable optical of Example 7 was carried out in the same manner as in Example 1 except that it was used in a weight ratio of 2EHA / LA / IBOA / IBOMA / 4HBA / ACMO = 44/5/38/2/9/2. The adhesive sheet for was prepared.

Example 8

The partially copolymerized acrylic copolymer according to Example 1, wherein each monomer is

The ultraviolet curable optical adhesive sheet of Example 8 was prepared in the same manner as in Example 1 except that it was used in a weight ratio of 2EHA / BA / IBOA / 4HEA / ACMO = 44/5/40/9/2. Prepared.

Example 9

The partially copolymerized acrylic copolymer according to Example 1, wherein each monomer is

Example was carried out in the same manner as in Example 1 except that it was used in a weight ratio of 2EHA / BA / LA / IBOA / 4HBA / ACMO / = 42/5/5/37/9/2 (mass parts) The ultraviolet curable optical adhesive sheet of 9 was manufactured.

Comparative Example 1

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. It was carried out in the same manner as in Example 1 except that 0.05 parts by weight of Irgacure 184D, 0.05 parts by weight of Irgacure 651, 0.05 parts by weight of TPO, 0.5 parts by weight of benzophenone, and 0.5 parts by weight of GMA were added. And the ultraviolet curable optical adhesive sheet of Comparative Example 1 were prepared.

Comparative Example 2

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. It was carried out in the same manner as in Example 1, except that 0.05 parts by weight of Irgacure 184D, 0.05 parts by weight of Irgacure 651, 0.05 parts by weight of TPO, 0.3 parts by weight of Irgacure 250, and 0.5 parts by weight of GMA were added. To prepare an ultraviolet curable optical adhesive sheet of Comparative Example 2.

Comparative Example 3

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. Ultraviolet curing type of Comparative Example 3 was carried out in the same manner as in Example 1 except for adding in a ratio of 0.05 parts by weight of Irgacure 184D, 0.05 parts by weight of Irgacure 651, 0.05 parts by weight of TPO, 0.5 parts by weight of GMA An optical adhesive sheet was prepared.

Comparative Example 4

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. Ultraviolet rays of Comparative Example 4 were carried out in the same manner as in Example 1, except that 0.05 parts by weight of Irgacure 184D, 0.3 parts by weight of Irgacure 250, 0.08 parts by weight of TPO, and 0.5 parts by weight of GMA were added based on 100 parts by weight of the syrup. The curable optical adhesive sheet was produced.

Comparative Example 5

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. Ultraviolet curing type of Comparative Example 5 was carried out in the same manner as in Example 1 except for adding in a ratio of 0.05 parts by weight of Irgacure 184D, 0.05 parts by weight of TPO, 0.5 parts by weight of benzophenone, 0.5 parts by weight of GMA based on 100 parts by weight of the syrup An optical adhesive sheet was prepared.

Comparative Example 6

A partially polymerized acrylic copolymer syrup was prepared in the same manner as in Example 1. UV curable optical adhesive sheet of Comparative Example 6 was carried out in the same manner as in Example 1, except that 0.3 parts by weight of Irgacure 250, 0.5 parts by weight of benzophenone, and 0.5 parts by weight of GMA were added based on 100 parts by weight of the syrup. Was prepared.

Experimental Example

Stress Relexation

Stress Relexation was measured for the adhesive sheets of Examples 1-9 and Comparative Examples 1-6 by the following method:

It measured at 25% of Strain and 70 degreeC using AR-2 which is a viscoelasticity measuring apparatus manufactured by TA Instruments.

After removing the release film supporting both sides of the UV curable optical adhesive sheet, the adhesive was laminated to a thickness of 500 μm and punched with a jig having a diameter of 8 mm to prepare a specimen. Then, the Strain 25% relative to the specimen, measuring the modulus was added to SR _.1second S _0, i.e., 0.1 seconds prior to UV irradiation at 25% Strain 70 ℃, and measuring the modulus was added to 25% Strain 300 seconds, The SR before UV irradiation was measured by the following Equation 1:

[Equation 1]

Stress Relaxation (%) = S _300seconds / S _{0 .1seconds} x 100

In the formula 1, S _{0 .1second} is the modulus measured after adding 25% Strain 0.1 seconds at a temperature condition of 70 ℃ for the adhesive, _300seconds S is 300 seconds 25% Strain at a temperature condition of 70 ℃ for adhesives The modulus measured after adding.

Then, ultraviolet radiation (wavelength: 240nm to 440nm wavelength of UV lamps of the light is emitted in all, the ultraviolet ray irradiation quantity: 4500mJ) After that, the above SR S _{0 .1second} same manner (i.e., at 25% Strain, 70 ℃ for the specimen, That is, the modulus is measured after applying 25% strain for 0.1 second, the modulus is measured after applying 25% strain for 300 seconds, and the strain is measured by applying the strain using the above formula (1). The subsequent SR value was measured.

The results are shown in Table 1 and Table 2.

Example Composition and Composition Ratio (Weight) of Partially Polymerized Acrylic Copolymer UV (%) before UV After UV SR (%)
One 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 0.06 0.23 2 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/3/37/2/11/2 0.07 0.24 3 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 43/3/37/2/13/2 0.09 0.24 4 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO
= 42/5/40/2/9/2 0.08 0.22 5 2EHA / IBOA / 2HEA / ACMO
= 46/43/9/2 0.07 0.25 6 2EHA / LA / IBOA / IBOMA / 4HBA / ACMO
= 45/5/37/2/7/2/2 0.05 0.25 7 2EHA / LA / IBOA / IBOMA / 4HBA / ACMO
= 44/5/38/2/9/2 0.07 0.23 8 2EHA / BA / IBOA / 2HEA / ACMO
= 44/5/40/9/2 0.06 0.23 9 2EHA / BA / LA / IBOA / 4HBA / ACMO
= 42/5/5/37/9/2 0.05 0.22

Composition and Composition Ratio (Weight) of Partially Polymerized Acrylic Copolymer Post composition and composition ratio (weight) UV before SR After UV SR
Comparative Example 1 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 184D / 651 / TPO / BP / GMA
= 0.05 / 0.05 / 0.08 / 0.5 / 0.5 0.06 0.14 Comparative Example 2 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 184D / 651 / TPO / 250 / GMA
= 0.05 / 0.05 / 0.08 / 0.3 / 0.5 0.07 0.13 Comparative Example 3 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 184D / 651 / TPO / GMA
= 0.05 / 0.05 / 0.08 / 0.5 0.06 0.07 Comparative Example 4 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 184D / 250 / TPO / GMA
= 0.05 / 0.3 / 0.08 / 0.5 0.02 0.05 Comparative Example 5 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 184D / TPO / BP / GMA
= 0.05 / 0.08 / 0.5 / 0.5 0.02 0.07 Comparative Example 6 2EHA / LA / IBOA / IBOMA / 2HEA / ACMO = 45/5/37/2/9/2 250 / BP / GMA
= 0.3 / 0.5 / 0.5 * *

^* SR cannot be measured because no film is formed

Adhesive Step Cover

Cover windows used in cell phones have a surface coating with a black or white printed frame around the edges. The step height of the printed frame was about 20 μm. The adhesive must overcome the black printed step height, and the X coverage black printed step glass (Samsung Technoglass) was used to visually observe the step coverage ability to confirm the coverage of the black or white printed step.

For the adhesives of Examples 1 to 9 and Comparative Examples 1 to 6, step coverage was evaluated by the following method:

After the release film of the adhesive was separated, PET film (SKC Kolon) was laminated using a roll laminating machine under the following conditions.

Applied Pressure: 6kgf

Application speed: 60mm / sec

Application temperature: 23 ℃

Then, after separating the other release film using a vacuum polymer on the X-marked black or white printing step glass (Samsung Techno Glass), the application pressure: 0.02Mpa, application time: 6sec, vacuum pressure: 30Pa or less, application temperature: 23 It was laminated at ℃, and had a process of AutoClave (application pressure: 6bar, application time: 15min, application temperature: 70 ℃). Thereafter, the step coverage ability was evaluated (OK: there was no stepped area bubble when visually observed, and NG: stepped area bubble was observed when visually observed). The results are shown in Table 3.

permeability  bubble

After assembling the window and the module including black or white printing step, it has an AutoClave process to remove bubbles generated during assembly. In the process of removing the vacuum pressure during the AutoClave process, bubbles that have been pushed back to normal pressure are introduced into the black or white printing step area over time. This causes a problem of permeable bubbles. For the adhesives of Examples 1 to 9 and Comparative Examples 1 to 6, evaluation of the generation of permeable bubbles was performed by the following method and the results are shown in Table 3 below:

For the adhesives of Examples 1 to 9 and Comparative Examples 1 to 6, the light silicon release treatment film was removed from one side, and the sheet was applied to the POL substrate, which is the top surface of the OLED and LCD module, using a rubber roller.

Lamination application conditions using the rubber roller are as follows.

Applied Pressure: 6kgf

Application speed: 60mm / sec

Application temperature: 23 ℃

Thereafter, the heavy silicon release film was removed from the remaining surface of the adhesive, and the adhesive sheet was applied to the slide glass substrate by laminating using a vacuum collector.

Lamination conditions using a vacuum polymerizer are as follows.

Applied Pressure: 0.02Mpa

Application time: 6sec

Vacuum pressure: 30 Pa or less

Application temperature: 23 ℃

After the application, the process of removing bubbles generated during assembly of the laminate using the autoclave equipment was applied.

AutoClave application conditions are as follows.

Applied Pressure: 6bar

Application time: 15min

Application temperature: 70 ℃

The distance of permeable bubbles to the module assembly was determined in the following way:

After the autoclave was carried out in the above-described manner with respect to the assembly, the air bubbles were observed at the outermost portion of the slide glass through an optical microscope, and then the distance from the outermost surface to the bubbles was measured.

Permeability bubble evaluation (OK: less than 0.6 mm, NG: 0.6 mm or more-> likely to expand to the visible area) The results are shown in Table 3.

Reliability bubble

After assembling the windows and modules with black or white printing steps, the assembly has a high temperature, high humidity reliability process. The adhesive adhered to the black or white printing step portion is deformed under high temperature and high humidity conditions when the crosslinking density is low (when the SR is low), causing the step to be lifted and causing bubble problems. In order to suppress bubble generation under such high temperature and high humidity reliability conditions, the bubble problem can be solved by improving the crosslinking density of the adhesive (by increasing SR) and minimizing the deformation of the adhesive under the reliability conditions.

Reliability bubbles for the module assembly were identified in the following manner:

After the autoclave is carried out by the above method for the assembly, UV irradiation process (post-curing, secondary curing, UV lamp having a broad wavelength in the range of 240 nm to 440 nm, UV irradiation amount: 4000 mJ), and high temperature and high humidity (85 ° C.) are performed. (85% RH), the assembly was left to stand and the state of the assembly after 240hr was visually observed (OK without bubbles, NG when bubbles are generated), and the results are shown in Table 3.

Step coverage Permeable air bubbles Reliability bubble Example 1 OK 0.32 OK Example 2 OK 0.28 OK Example 3 OK 0.35 OK Example 4 OK 0.42 OK Example 5 OK 0.33 OK Example 6 OK 0.37 OK Example 7 OK 0.41 OK Example 8 OK 0.42 OK Example 9 OK 0.39 OK Comparative Example 1 OK 0.40 NG Comparative Example 2 OK 0.39 NG Comparative Example 3 OK 0.37 NG Comparative Example 4 OK 0.62 NG Comparative Example 5 OK 0.63 NG Comparative Example 6 NG NG NG

From the above results, the adhesives of Examples 1 to 9 had a SR of 0.05 to 0.15% before UV irradiation, and the step coverage was good and the permeable bubbles were located within 0.6 mm, whereas the adhesives of Comparative Examples 1 to 5 It can be seen that the adhesive is located in the area where the permeable bubble is visible, although bubbles are not generated at the stepped portion with the SR of less than 0.05 before UV irradiation. In addition, the adhesives of Examples 1 to 9 do not generate reliable bubbles with SR of 0.18% or more after UV irradiation, whereas the adhesives of Comparative Examples 1 to 5 having SR of less than 0.18% after UV irradiation have a reliability evaluation. It can be seen that bubbles have occurred.

Claims (10)

An acrylic copolymer in which at least one monomer selected from a low temperature glass transition (meth) acrylic monomer, a high temperature glass transition (meth) acrylic monomer, and a (meth) acrylic monomer having a hydrophilic group is partially polymerized; Photoinitiators having a benzophenone structure; (Meth) acrylates having an oxetane structure; Cationic photoinitiators; And a long wavelength ultraviolet ray capable of activating a photoinitiator having a radiation reactive site activated by radiation of the long wavelength in an ultraviolet curable optical adhesive composition comprising a photoinitiator having a radiation reactive site activated by radiation of a longer wavelength than the photoinitiator. UV-curable optical adhesive formed by irradiation with
The cationic photoinitiator is for ring-opening the oxetane structure of the (meth) acrylate having the oxetane structure which is ion-reactive,
When forming the assembly for assembling the module with the window including the black or white printing step, the adhesive is subjected to the AutoClave process to remove the bubbles generated during the assembly, the atmospheric pressure in the process of removing the vacuum pressure during the AutoClave process UV-curable optics adhesives that penetrate the air bubbles that have been pushed out as they enter the black or white printing step area over time satisfy a condition that the distance from the outermost side of the window to the air bubbles is less than 0.6 mm. . The ultraviolet-curable optical adhesive according to claim 1, wherein the low-temperature glass transition (meth) acryl monomer has a glass transition temperature of its homopolymer in a range of -100 ° C to 40 ° C. The adhesive for ultraviolet curable optics according to claim 1, wherein the high temperature glass transition (meth) acrylic monomer has a glass transition temperature of its homopolymer in a range of 50 ° C to 180 ° C. The ultraviolet curable optical adhesive according to claim 1, wherein the (meth) acryl monomer having a hydrophilic group is a (meth) acryl monomer having a hydrophilic group of a hydroxy group, a carboxyl group, a urethane group, an amine group, or an amide group. The ultraviolet curable optical adhesive according to claim 1, wherein the photoinitiator having a benzophenone structure is acryloyl benzophenone, benzophenone, dichlorobenzophenone, p-phenylbenzophenone, or 4,4-diethylaminobenzophenone. . The method of claim 1, wherein the cationic photoinitiator is 4-methylphenyl, 4- (2-methylpropyl) phenyl (4- (2-methylpropyl) phenyl), hexafluorophosphate, triaryl UV curable optic adhesives that are triarylsulphonium salts, propylene carbonate, or Igacure 250. The polymerization weight ratio of the said low temperature glass transition (meth) acrylic monomer, the said high temperature glass transition (meth) acrylic monomer, and the (meth) acryl monomer which has the said hydrophilic group is 20-50: 20-50: 1 UV-curable optical adhesive agent of -20. Ultraviolet rays formed by irradiating the ultraviolet-curable optical composition according to any one of claims 1 to 7, wherein the ultraviolet radiation of the long wavelength that can activate the photoinitiator having a radiation reactive site activated by the radiation of the long wavelength Curable optic adhesive. Acryl partially polymerized by irradiating UV light to a mixture comprising a low temperature glass transition (meth) acrylic monomer, a high temperature glass transition (meth) acrylic monomer, and at least one monomer selected from a (meth) acryl monomer having a hydrophilic group and a photoinitiator Preparing a copolymer;
The partially polymerized acrylic copolymer has a photoinitiator having a benzophenone structure, a (meth) acrylate having an oxetane structure, a cationic photoinitiator, and a reactive site that is activated by longer wavelength radiation than the benzophenone photoinitiator. Adding and blending the photoinitiator to form an adhesive precursor composition;
Providing the adhesive precursor composition to the surface of the release film,
A method of manufacturing an ultraviolet curable optical adhesive, comprising irradiating the precursor composition with radiation of a long wavelength capable of activating a photoinitiator having a radiation reactive site activated by the radiation of the long wavelength to form an ultraviolet curable optical adhesive. As
The cationic photoinitiator is for ring-opening the oxetane structure of the (meth) acrylate having the oxetane structure which is ion-reactive,
When forming the assembly for assembling the module with the window including the black or white printing step, the adhesive is subjected to the AutoClave process to remove the bubbles generated during the assembly, the atmospheric pressure in the process of removing the vacuum pressure during the AutoClave process UV-curable optics adhesives that penetrate the air bubbles that have been pushed out as they enter the black or white printing step area over time satisfy a condition that the distance from the outermost side of the window to the air bubbles is less than 0.6 mm. Method of preparation. The ultraviolet curable optical adhesive according to any one of claims 1 to 7, wherein the adhesive for ultraviolet curable optics has a release film on one or both surfaces thereof.

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