KR102393003B1 - Uv curable resin composition - Google Patents

Abstract

An object of the present invention is to provide a UV-curable resin composition capable of easily peeling and reworking an LCD from an adherend even at room temperature and providing good adhesion, and an adhesive sheet comprising the same.
(A) a UV curable prepolymer, (B) a UV curable polyfunctional monomer, (C) a photoinitiator, and (D) a silane coupling agent;
The component (A) is urethane (meth) acrylate,
With respect to 100 mass parts of said (A) component, content of 15-60 mass parts of said (B) component, content of said (C)component 0.5 mass part or more, content of said (D)component is 0.1-5 mass Madam, UV curable resin composition.

Description

UV curable resin composition {UV CURABLE RESIN COMPOSITION}

The present invention relates to a UV curable resin composition usable in a liquid crystal display part and an adhesive sheet comprising the same.

Currently, liquid crystal displays (LCDs) have become extremely common display devices with the spread of digitalized electronic devices, and are used as display units for various devices such as liquid crystal TVs, PC displays, mobile phone terminals, portable game consoles, electronic calculators, and watches. there is. In particular, in recent years, for the purpose of imparting a 3D function, there exist those in which a patterning retardation plate made of glass is adhered to an LCD.

Here, the LCD to which the retardation plate is adhered may be recovered after use, and only the LCD may be reused. For example, it is calculated|required to peel a phase difference plate from LCD, and to rework LCD. At this time, in the conventional method, the entire LCD is cooled (in other words, the adhesive is cooled), and the retardation plate is peeled off from the LCD. However, in this method, equipment for cooling is required, and it cannot be said that workability is also favorable. Further, since both the retardation plate and the LCD have rigidity, there has been a problem that either one is damaged when peeling. That is, it was difficult to rework the LCD by easily peeling the conventional adhesive sheet after bonding the LCD and the retardation plate.

In order to solve such a problem, the adhesive sheet which can peel easily even if a to-be-adhered body is hard like glass at normal temperature is examined. For example, Patent Document 1 proposes a transparent adhesive film containing an adhesive component and a gas generating agent that generates gas by irradiating ultraviolet rays. Moreover, in patent document 2, the heat and actinic ray hardening type (photocurable type) adhesive composition is proposed.

Japanese Patent Laid-Open No. 2016-56244 Japanese Patent Publication No. 2011-508814

However, the transparent adhesive film described in Patent Document 1 needs to be exposed at the time of rework, and the actinic ray-curable (photocurable) adhesive composition described in Patent Document 2 is heated at the time of rework, and an adhesive is used using a wire. The adhesive is being removed by cutting and advancing. That is, the present situation is that an adhesive sheet capable of easily peeling an LCD from an adherend at normal temperature cannot be obtained from an adherend while ensuring good adhesiveness.

In view of the above circumstances, it is an object of the present invention to provide a UV curable resin composition capable of easily peeling and reworking an LCD from an adherend even at room temperature and providing good adhesion properties and an adhesive sheet comprising the same do it with

The present inventors have intensively studied to solve the above problems, (A) a UV curable prepolymer, (B) a UV curable polyfunctional monomer, (C) a photopolymerization initiator, and (D) a silane coupling agent, The component (A) is urethane (meth)acrylate, and the content of the component (B) is 15 to 60 parts by mass, and the content of the component (C) is 0.5 parts by mass with respect to 100 parts by mass of the component (A). As mentioned above, the UV curable resin composition whose content of the said (D)component is 0.1-5 mass parts discovers that the said subject can be solved, and completed this invention.

That is, the present invention is as follows.

[One]

(A) a UV curable prepolymer, (B) a UV curable polyfunctional monomer, (C) a photoinitiator, and (D) a silane coupling agent;

The component (A) is urethane (meth) acrylate,

With respect to 100 mass parts of said (A) component, content of 15-60 mass parts of said (B) component, content of said (C)component 0.5 mass part or more, content of said (D)component is 0.1-5 mass Madam, UV curable resin composition.

[2]

The urethane (meth) acrylate is selected from the group consisting of urethane (meth) acrylate having a polycarbonate skeleton, urethane (meth) acrylate having a polyether skeleton, and urethane (meth) acrylate having a polyester skeleton The UV curable resin composition according to the above [1], which is at least one type.

[3]

The UV curable resin composition according to [1] or [2], wherein the urethane (meth)acrylate has a weight average molecular weight of 10,000 to 100,000 and a double bond equivalent of 1,000 to 5,000 g/eq.

[4]

The UV curable resin composition according to any one of [1] to [3], wherein the (B) UV curable polyfunctional monomer is a (meth)acrylic monomer having two or more functional groups.

[5]

The UV curable resin composition according to any one of [1] to [4], wherein the (C) photopolymerization initiator is an acylphosphine oxide-based photopolymerization initiator.

[6]

The UV curable resin composition according to [5], wherein the acylphosphine oxide-based photopolymerization initiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[7]

The UV curable resin composition according to any one of [1] to [6], wherein the (D) silane coupling agent is a silane coupling agent having a (meth)acryl group.

[8]

An adhesive sheet comprising the UV curable resin composition according to any one of [1] to [7].

[9]

The adhesive sheet according to the above [8], wherein the film thickness after drying is 10-250 µm.

[10]

It is a 3D liquid crystal panel in which an LCD and a patterning retarder are laminated.

A 3D liquid crystal panel in which the LCD and the retarder are adhered by the adhesive sheet according to the above [8] or [9].

[11]

The 3D liquid crystal panel according to [10], wherein the patterning retardation plate is a patterned glass plate.

The adhesive sheet comprising the UV curable resin composition of the present invention can easily peel and rework the LCD from the adherend even at room temperature, and can provide good adhesiveness.

EMBODIMENT OF THE INVENTION Hereinafter, it describes in detail about the form (henceforth "this embodiment") for implementing this invention. In addition, this invention is not limited to the following embodiment, It can variously deform and implement within the range of the summary.

The UV curable resin composition in this embodiment,

(A) a UV curable prepolymer, (B) a UV curable polyfunctional monomer, (C) a photoinitiator, and (D) a silane coupling agent;

The component (A) is urethane (meth) acrylate,

With respect to 100 mass parts of said (A) component, content of 15-60 mass parts of said (B) component, content of said (C)component 0.5 mass part or more, content of said (D)component is 0.1-5 mass is wealth

[(A) UV-curable prepolymer]

The UV curable resin composition in this embodiment contains (A) UV curable prepolymer (henceforth "(A) component"). The UV curable prepolymer is not particularly limited as long as it is a urethane (meth)acrylate having a urethane structure in the main chain and a (meth)acryl group in the side chain. It does not specifically limit as urethane (meth)acrylate, For example, urethane (meth)acrylate which has polycarbonate backbone, urethane (meth)acrylate which has polyether backbone, urethane (meth)acrylate which has polyester backbone ) acrylate etc. are mentioned, Among them, the urethane (meth)acrylate which has a polycarbonate frame|skeleton from a non-yellowing viewpoint of a cured adhesive sheet is preferable.

The urethane (meth)acrylate having a polycarbonate skeleton refers to a prepolymer having a polycarbonate structure and a urethane structure in a main chain and a (meth)acryl group in a side chain. Urethane (meth)acrylate having a polycarbonate skeleton can be obtained by, for example, reacting polycarbonate diol, diisocyanate, and carboxylic acid diol, followed by reacting glycidyl (meth) acrylate. .

The weight average molecular weight of polycarbonate diol becomes like this. Preferably it is 170-1,000, More preferably, it is 300-700, More preferably, it is 400-600. When the weight average molecular weight of the polycarbonate diol is within the above range, the urethane prepolymer main chain tends to have film properties required for rework.

It does not specifically limit as diisocyanate, For example, 2, 4- tolylene diisocyanate (2,4-TDI), 2, 6- tolylene diisocyanate (2,6-TDI), 4,4'- diphenylmethane Diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylenediisocyanate, xylylene diisocyanate (XDI), tetramethylxylyl aromatic isocyanates such as rendiisocyanate (TMXDI), tolidine diisocyanate (TODI), and 1,5-naphthalene diisocyanate (NDI); aliphatic polyisocyanates such as hexamethylene isocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and methyl norbornane diisocyanate (NBDI); and alicyclic polyisocyanates such as transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI) and H6XDI (hydrogenated XDI). , hexamethylene diisocyanate is preferred.

It does not specifically limit as carboxylic acid diol, For example, dimethylol butanoic acid, dimethylol propionic acid, etc. are mentioned.

The urethane (meth)acrylate having a polyether skeleton refers to a prepolymer having a polyether structure and a urethane structure in the main chain, and a (meth)acrylic group in the side chain, and the urethane (meth)acrylate having a polyester skeleton is the main chain It has a polyester structure and a urethane structure, and refers to the prepolymer which has a (meth)acryl group in a side chain. These prepolymers can be obtained by the same method as the urethane (meth)acrylate having a polycarbonate skeleton, except that polyetherdiol and polyesterdiol are respectively used instead of polycarbonatediol. At this time, the preferable weight average molecular weight of polyether diol and polyester diol is the same as the preferable weight average molecular weight of the above-mentioned polycarbonate diol.

(A) The weight average molecular weight of component becomes like this. Preferably it is 10,000-100,000, More preferably, it is 30,000-70,000, More preferably, it is 40,000-60,000. When a weight average molecular weight is the said range, film forming property and sclerosis|hardenability become favorable, and there exists a tendency for long-term reliability to become favorable.

Here, the weight average molecular weight refers to a value measured by gel permeation chromatography (GPC) using standard polystyrene having an average molecular weight of about 500 to about 1 million.

(A) The double bond equivalent of component becomes like this. Preferably it is 1,000-5,000 g/eq, More preferably, it is 1,500-2,500 g/eq, More preferably, it is 1800-2,200 g/eq. If the double bond equivalent is within the above range, there is little influence of cure shrinkage, excellent long-term reliability, and easy curing and easy rework.

Here, the double bond equivalent refers to a value calculated from the solid content mass (g) of the carboxyl group-containing (meth)acrylate/the number of moles (g/mol) of the compound having an oxirane ring and an ethylenically unsaturated bond.

(A) The glass transition temperature (Tg) of component becomes like this. Preferably it is -10-20 degreeC, More preferably, it is -5-15 degreeC, More preferably, it is 0-10 degreeC. There exists a tendency for the balance of long-term reliability and rework property to become favorable that a glass transition temperature is the said range.

Here, the glass transition temperature refers to a value measured by dynamic viscoelasticity measurement (DMA).

[(B) UV-curable polyfunctional monomer]

The UV curable resin composition in this embodiment contains (B) a UV curable polyfunctional monomer (henceforth "(B) component"). In order to enable the rework of the LCD, it is necessary to increase the viscoelasticity at room temperature, but in this embodiment, by adding a UV curable polyfunctional monomer to the UV curable prepolymer, the crosslinking density after curing is increased, and at room temperature increase the viscoelasticity of Here, the viscoelasticity of the UV curable resin composition can be measured by dynamic viscoelasticity measurement (DMA), and preferably, the storage modulus at room temperature (25° C.) after curing is 1.0×10 ⁸ to 1.0×10 ¹⁰ Pa, and more Preferably it is 4.0x10 ⁸ to 5.0x10 ⁹ Pa, More preferably, it is 6.0x10 ⁸ to 3.0x10 ⁹ Pa.

(B) It does not specifically limit as a component, For example, a (meth)acrylic monomer is mentioned, Especially, from a viewpoint of raising a crosslinking density and improving rework property (meth) which has two or more functional groups. Acrylic monomers are preferred.

(B) Specifically, as a component having two functional groups, 1,4-butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecanedimethanol Diacrylate is mentioned, As a thing of three functional groups, trimethylol propane triacrylate, trimethylol methane tri(meth)acrylate, trimethylol propane propylene oxide modified|denatured tri(meth)acrylate is mentioned, A functional group 4 or more, dipentaerythritol tetra (meth) acrylate, pentaerythritol ethylene oxide modified tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethylene oxide modified tetra (meth) ) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol hexaacrylate, and the like, among them, from the viewpoint of reworkability, a (meth) acrylic monomer having 4 or more functional groups is preferable. , more preferably dipentaerythritol hexaacrylate having 6 functional groups.

(A) Content of (B) component with respect to 100 mass parts of components is 15-60 mass parts, Preferably it is 18-40 mass parts, More preferably, it is 20-30 mass parts. (B) When content of component is less than 15 mass parts, the adhesiveness after hardening is high, the rework property in normal temperature is inferior, and when it exceeds 60 mass parts, adhesiveness is not enough and long-term reliability is inferior. In addition, when the content of the component (B) with respect to 100 parts by mass of the component (A) is adjusted to the above range, since the melt viscosity of the resin composition is maintained within a certain range, it is difficult to cause joint non-uniformity or image confusion. There is an advantage.

[(C) Photoinitiator]

The UV curable resin composition in this embodiment contains (C) a photoinitiator (henceforth "(C)component"). It does not specifically limit as a photoinitiator, For example, any photoinitiator, such as an acyl phosphine oxide type photoinitiator, an alkylphenone type photoinitiator, an intramolecular hydrogen extraction type photoinitiator, can be used, Among them, reactivity and hardening From a viewpoint of uniformity, an acylphosphine oxide type|system|group photoinitiator is preferable. Specific examples thereof include 2,4,6-trimethylbenzoylphenylphosphine oxide, 2,2-dimethoxy-1,2-diphenylethan-1-one, and phenylglyoxylic acid methyl ester. Among them, 2,4,6-trimethylbenzoylphenylphosphine oxide is preferable from a viewpoint of high radical generation efficiency and deep-part sclerosis|hardenability.

(A) Content of (C)component with respect to 100 mass parts of components is 0.5 mass parts or more, Preferably it is 1.0 mass parts or more, More preferably, it is 1.5 mass parts or more. (C) It exists in the tendency for hardening reactivity to become favorable that content of a photoinitiator is the above, and to improve rework property and long-term reliability. (C) Although it does not specifically limit as an upper limit of content of a component, Since there exists a tendency for an optical characteristic to fall when there is too much, it is preferable that it is 7.0 mass parts or less.

[(D) Silane Coupling Agent]

The UV curable resin composition in this embodiment further contains (D) a silane coupling agent (henceforth "(D) component") in addition to the said (A)-(C) component. As described above, the UV curable resin composition of the present embodiment contains the UV curable polyfunctional monomer, thereby increasing the viscoelasticity at room temperature and enabling the rework of the LCP. On the other hand, when viscoelasticity is high, there exists a tendency for adhesiveness with a to-be-adhered body to fall. In this embodiment, adhesive force is maintained by containing a silane coupling agent in a UV curable resin composition, and long-term reliability in the case of a to-be-adhered body especially a glass plate improves.

(D) It does not specifically limit as a component, For example, any silane coupling agent, such as a monomer type silane coupling agent, an alkoxy oligomer type silane coupling agent, and a polyfunctional type silane coupling agent, can be used. Especially, the silane coupling agent which has a (meth)acryl group is preferable and 3-acryloxypropyl trimethoxysilane is more preferable from a viewpoint of maintaining the adhesive improvement in case a to-be-adhered body is glass, and long-term reliability.

(A) Content of (D)component with respect to 100 mass parts of components is 0.1-5 mass parts, Preferably it is 0.5-3.0 mass parts, More preferably, it is 0.5-1.5 mass parts. (D) There exists a tendency for the balance of long-term reliability and rework property to become favorable as content of a component is the said range.

[Other Ingredients]

In the UV curable resin composition of the present embodiment, in addition to the components (A) to (D) described above, various fillers such as silica, alumina and hydrated alumina, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, antifoaming agents , a coloring pigment, an organic solvent, etc., may contain additives which may be usually added to the adhesive.

[Adhesive sheet]

The adhesive sheet in this embodiment contains the above-mentioned UV curable resin composition. Specifically, for example, after coating the resin composition on a protective film such as PET and drying it, a protective film is also provided on the opposite surface to obtain an adhesive sheet provided with a protective film on both surfaces. In particular, it is preferable to apply a UV curable resin composition to a varnish using an organic solvent, then apply it on a protective film and dry it. Although it does not specifically limit as an organic solvent used at this time, For example, toluene, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether, dimethylacetamide, etc. are mentioned. Among them, methyl ethyl ketone is preferable from the viewpoint of solubility. Moreover, to [ content of the organic solvent in a varnish / 100 mass parts of (A) component), Preferably it is 30-90 mass parts, More preferably, it is 40-70 mass parts.

It does not specifically limit as a protective film, For example, the film which consists of 1 or more types of resin chosen from the group which consists of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate is mentioned, Among them, manufacturing cost is reduced The film which consists of a polyethylene terephthalate resin from a viewpoint of doing is preferable.

The release process may be given to the surface to which the resin composition is apply|coated to a protective film. Since it becomes possible to peel a protective film easily at the time of use by the release process being given to a protective film, handleability improves. The release treatment is not particularly limited, and for example, a release agent such as a silicone-based release agent, a fluorine-based release agent, or a long-chain alkyl graft polymer-based release agent, or a method of surface treatment by plasma treatment, etc. can be used.

As a method of apply|coating a UV curable resin composition to a protective film, a comma coater, a die coater, a gravure coater, etc. can be employ|adopted suitably according to application|coating thickness.

Drying of the UV curable resin composition can be performed with an in-line dryer or the like, and the drying conditions at that time can be appropriately adjusted according to the type and amount of each component. The thickness of the adhesive sheet after drying becomes like this. Preferably it is 10-250 micrometers, More preferably, it is 25-125 micrometers, More preferably, it is 30-75 micrometers. When the thickness of an adhesive sheet is the said range, adhesiveness becomes favorable and long-term reliability improves. In the present embodiment, the long-term reliability specifically includes that the LCD and the patterning retarder have good adhesion, so that misalignment is less likely to occur, and as a result, the viewer can observe a good 3D image. In addition, when the thickness of the adhesive sheet is within the above range, the distance between the LCD and the patterning retarder becomes appropriate, and when viewing a 3D image, an appropriate viewing angle can be secured.

[3D liquid crystal panel]

The 3D liquid crystal panel in this embodiment is one in which an LCD and a patterning retardation plate are laminated, and the LCD and the retardation plate are adhered to each other by the adhesive sheet in the present embodiment. A 3D liquid crystal panel can be obtained by, for example, bonding an adhesive sheet to a retardation plate, bonding an LCD from it, and UV-curing an adhesive sheet by irradiating UV.

As a patterning retardation plate, the glass plate in which the pattern was formed can be used.

In addition, the UV curable resin composition in this embodiment can be used in not only the use of a 3D liquid crystal panel, but in all the uses which assumed that display apparatuses, such as LCD and organic electroluminescent, are reworked. As such a use, a touch sensor panel, digital signage, etc. are mentioned, for example.

[Example]

Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited only to these Examples.

Each component and material used in the Example and the comparative example is as follows.

[Component (A): UV-curable prepolymer]

According to the following Synthesis Examples 1 to 3 and Comparative Synthesis Example 1, UV-curable prepolymers (a) to (d) were produced.

[(B) component: UV curable polyfunctional monomer]

(1) UV-curable polyfunctional monomer (a)

Dipentaerythritol Hexaacrylate

Daicel Allnex Co., Ltd., product name "DPHA"

(2) UV-curable polyfunctional monomer (b)

Tricyclodecanedimethanol diacrylate

Daicel Allnex, product name "IRR214-K"

(3) UV-curable polyfunctional monomer (c)

trimethylolpropane triacrylate

Daicel Allnex, product name "TMPTA"

(4) UV-curable polyfunctional monomer (d)

Ethoxylated phenyl acrylate (monofunctional)

Daicel Allnex, product name "EBECRYL110"

[(C) component: photoinitiator]

(1) Photoinitiator (a)

2,4,6-trimethylbenzoylphenylphosphine oxide

BASF company make, brand name "Irgacure TPO", acylphosphine oxide type photoinitiator

(2) photopolymerization initiator (b)

2,2-dimethoxy-1,2-diphenylethan-1-one

BASF company make, brand name "Irgacure 651", alkylphenone-based photopolymerization initiator

(3) photopolymerization initiator (c)

Phenylglyoxylic acid methyl ester

BASF Corporation, trade name "Irgacure MBF", intramolecular hydrogen extraction type photopolymerization initiator

[(D) component: silane coupling agent]

(1) Silane coupling agent (a)

Monomeric Silane Coupling Agent

Shin-Etsu Chemical Co., Ltd. make, trade name "KBM-5103", 3-acryloxypropyltrimethoxysilane

(2) Silane coupling agent (b)

Alkoxy oligomer type silane coupling agent

Made by Shin-Etsu Chemical High School, trade name "KR-513"

(3) silane coupling agent (c)

Polyfunctional Silane Coupling Agent

Made by Shin-Etsu Chemical High School, brand name "X-12-1050"

Each evaluation method and measurement method are as follows.

[Rework Castle]

(1) Sample production procedure

The PET film on one side of the adhesive sheet was peeled off, laminated to glass (0.7 t, 19 inches), and autoclaved. Lamination is carried out using roll lamination at a lami roll temperature of 25 to 40 ° C., a lami roll linear pressure of 1.0 to 2.0 kgf / cm, and a lami roll speed of 0.3 to 2.0 m / min, and the autoclave is performed at a temperature of 60 ° C., a pressure of 0.6 MPa, The time was 10 min. After peeling off the other PET film, bonding with LCD and vacuum lamination, autoclaving process again, the test sample was obtained by UV exposure. The vacuum lamination was performed at a temperature of 25 to 50°C, a pressure of 0.01 to 0.05 MPa, a vacuum of 60 s, and a pressure of 30 s. The autoclave was implemented by the temperature of 60 degreeC, the pressure of 0.6 Mpa, and time of 1 hr. UV exposure was performed so that the accumulated light amount might be 3000 mJ/cm<2> using the ultrahigh pressure mercury lamp light source.

(2) Measurement method

After leaving the test sample at room temperature for 24 hr or more, damage to the adherend (glass, LCD) after peeling the glass was observed and evaluated according to the following.

(double-circle): Rework was possible easily without damaging a to-be-adhered body

(circle): Rework was possible without damaging a to-be-adhered body

×: Rework was difficult

[Adhesive]

(1) Sample production procedure

A test sample was produced by the same procedure as the reworkability.

(2) Measurement method

The test sample was left standing in a humid heat place. The conditions were a temperature of 50°C, a humidity of 80%, and a time of 240 hr. After that, it was left to stand at room temperature for 24 hours. The shift|offset|difference of the glass bonding position at the time of comparing with the time of leaving-to-stand start to a moist-heat machine, and the presence or absence of floating|lifting and foaming were observed, and it evaluated according to the following.

(circle): The position shift of glass, floating, and foaming did not generate|occur|produce

x: Position shift of glass, floating, and foaming generate|occur|produced

[Adhesiveness]

(1) Sample production procedure

A test sample was produced by the same procedure as the reworkability.

(2) Measurement method

The display of the test sample was lit and evaluated according to the following.

(circle): No bonding nonuniformity and 3D misalignment did not generate|occur|produce in a display image (there was no double image generation)

x: bonding nonuniformity and 3D shift|offset|difference generate|occur|produced in the display image (there was generation|occurrence|production of a double image)

[Optical Characteristics]

(1) Sample production procedure

The PET film on one side of the adhesive sheet was peeled off, and it was bonded to optical glass (square with a side of 40 mm) by vacuum lamination. The vacuum lamination was performed by the temperature of 25-50 degreeC, the pressure of 0.01-0.05 Mpa, 10 s of vacuumization, and 10 s of pressure. After peeling off the other PET film and bonding to optical glass under the conditions similar to the said vacuum lamination condition, it autoclaved and then UV exposure was carried out, and the test sample was obtained. The autoclave was implemented with the temperature of 60 degreeC, the pressure of 0.6 MPa, and time of 1 hr. UV exposure was performed so that the accumulated light amount might be 3000 mJ/cm<2> using the ultrahigh pressure mercury lamp light source.

The yellow index (YI) of the test sample was measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technology). Measurement conditions were C light source, transmission, and wavelength λ=380 to 760 nm.

◎: YI value less than 1.5

○: YI value 1.5 or more and less than 2

×: YI value 2 or more

(Synthesis Example 1) UV-curable prepolymer (a)

To a four-necked flask equipped with a thermometer, a cooling tube, and a stirring device, 33.3 parts by mass of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name: HDI, brand name: HDI) and 59.4 parts by mass of polycarbonate diol having a weight average molecular weight of 400 Parts by mass, 7.3 parts by mass of dimethylol butanoic acid, 1 part by mass of an organotin compound such as dibutyltin laurate as a catalyst, and 100 parts by mass of methyl ethyl ketone as an organic solvent were placed in a reaction vessel and reacted at 70° C. for 24 hours. .

In order to confirm the reaction status of the obtained compound, analysis was performed using an IR measuring instrument. In the IR chart, it was confirmed that the NCO characteristic absorption (2270 cm ^-1 ) of the compound was lost, and it was confirmed that the compound was a urethane having a carboxyl group.

Next, 100 parts by mass of the obtained urethane having a carboxyl group, 7.1 parts by mass of glycidyl methacrylate, 0.7 parts by mass of triethylamine as a catalyst, and 0.05 parts by mass of hydroquinone as a polymerization inhibitor were placed in a reaction vessel, and 12 at 75 ° C. A UV-curable prepolymer (a) was obtained by performing a time reaction and making it addition-react.

In addition, the addition reaction was terminated when the acid value measured according to the following method became 5 mgKOH/g or less. In addition, the obtained UV curable prepolymer (a) had a weight average molecular weight of 50,000, a solid content concentration of 50 mass %, a double bond equivalent of 2,000 g/eq, and Tg 5 degreeC.

(Acid value measurement method)

1 g of the solid content of the resin is weighed, a mixed solvent (mass ratio: toluene/methanol = 50/50) is added and dissolved, an appropriate amount of a phenolphthalein solution is added as an indicator, titrated with a 0.1N aqueous potassium hydroxide solution, and the formula (α) is The acid value was measured by

(in formula (α), x represents the acid value (mgKOH/g), Vf represents the appropriate amount (mL) of 0.1N KOH aqueous solution, Wp represents the mass (g) of the measured resin solution, and I The ratio (mass %) of the non-volatile matter in the measured resin solution is shown.)

(Synthesis Example 2) UV-curable prepolymer (b)

A UV curable prepolymer (b) was obtained in the same manner as in Synthesis Example 1 except that polyetherdiol was used instead of polycarbonatediol.

(Synthesis Example 3) UV-curable prepolymer (c)

A UV curable prepolymer (c) was obtained in the same manner as in Synthesis Example 1 except that polyesterdiol was used instead of polycarbonatediol.

(Comparative Synthesis Example 1) UV-curable prepolymer (d)

In a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a nitrogen introduction tube, 100.0 g of methoxypropanol propylene glycol monomethyl ether (PGM) as a polymerization solvent was charged, and the temperature was raised to 80° C. while stirring under a nitrogen stream. 13.5 parts by mass of styrene, 67 parts by mass of ethyl acrylate, 11.5 parts by mass of acrylic acid, and 0.5 g of azobisisobutyronitrile as a radical polymerization initiator mixed in advance at room temperature were added to this in a dropping funnel over 3 hours while kept at 80° C. dropped from After completion of the dropwise addition, the temperature was raised to 90°C while stirring the reaction solution, and the mixture was stirred for another 2 hours while maintaining the temperature of the reaction solution at 90°C to obtain a copolymer.

Next, 100 parts by mass of the obtained copolymer, 7.8 parts by mass of glycidyl methacrylate, 0.8 parts by mass of triethylamine as a catalyst, and 0.05 parts by mass of hydroquinone as a polymerization inhibitor were put in a reaction vessel, and reacted at 100° C. for 12 hours. was carried out and an addition reaction was performed to obtain a UV-curable prepolymer (d).

In addition, the addition reaction was terminated when the acid value became 5 mgKOH/g or less. In addition, the obtained UV curable prepolymer (d) had a weight average molecular weight of 45,000, a solid content concentration of 47 mass %, and Tg 3 degreeC.

(Example 1)

(1) Preparation of UV curable resin composition

In the reaction vessel, 100 parts by mass of the UV-curable prepolymer (a) is added, and 25 parts by mass of the UV-curable polyfunctional monomer (a), 1.5 parts by mass of the photoinitiator (a), 1 part by mass of the silane coupling agent (a) and a solvent 140 parts by mass of methyl ethyl ketone was added and stirred to obtain a resin composition.

(2) Preparation of adhesive sheet

The resin composition obtained in (1) above is coated on a PET film having a thickness of 38 μm so that the thickness after drying is 30 μm or more, dried at 130° C. for 5 minutes, a PET film is installed on the opposite side, and PET film on both sides An adhesive sheet provided with

Rework property, adhesiveness, bonding property, and optical characteristic were evaluated using the obtained adhesive sheet.

(Examples 2 to 20), (Comparative Examples 1 to 7)

A UV curable resin composition and an adhesive sheet were obtained in the same manner as in Example 1 except that the type and content of each component were changed as shown in Tables 1 to 3.

Rework property, adhesiveness, bonding property, and optical characteristic were evaluated using the obtained adhesive sheet.

The adhesive sheet containing the UV curable resin composition of the present invention has industrial applicability as an adhesive for liquid crystal display and the like.

Claims (11)

(A) a UV curable prepolymer, (B) a UV curable polyfunctional monomer, (C) a photoinitiator, and (D) a silane coupling agent;
The component (A) is urethane (meth) acrylate,
With respect to 100 mass parts of said (A) component, content of 15-60 mass parts of said (B) component, content of said (C)component 0.5 mass part or more, content of said (D)component is 0.1-5 mass Madam, it is a UV curable resin composition,
(C) the photopolymerization initiator is an acylphosphine oxide-based photopolymerization initiator,
After curing the UV curable resin composition, the storage modulus at room temperature (25° C.) is 6.0×10 ⁸ to 1.0×10 ¹⁰ Pa,
A UV curable resin composition having a YI value of less than 2 when a yellow index (YI) of the UV curable resin composition is prepared by the following method, and the yellow index (YI) of the produced adhesive sheet is measured by the following measuring method.
(Manufacturing method of adhesive sheet)
The UV curable resin composition is applied on a PET film of 38 μm so that the thickness after drying is 30 μm or more, dried at 130° C. for 5 minutes, a PET film is installed on the opposite side, and a PET film is provided on both sides. An adhesive sheet is obtained.
(Method of measuring YI)
The PET film on one side of the adhesive sheet is peeled off and bonded to optical glass (square with a side of 40 mm) by vacuum lamination. Vacuum lamination is carried out at a temperature of 25 to 50°C, a pressure of 0.01 to 0.05 MPa, a vacuum of 10s, and a pressure of 10s. After peeling the other PET film and bonding to optical glass under the conditions same as the conditions of the said vacuum lamination, autoclave process is performed, and then, a test sample is obtained by UV exposure. Autoclave is performed at a temperature of 60°C, a pressure of 0.6 MPa, and a time of 1 hour. UV exposure is performed using an ultra-high pressure mercury lamp light source so that the accumulated light amount is 3000 mJ/cm 2 . The yellow index (YI) of the test sample is measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technology). Measurement conditions are C light source, transmission, and wavelength λ=380 to 760 nm. According to claim 1, wherein the urethane (meth) acrylate is urethane (meth) acrylate having a polycarbonate skeleton, urethane (meth) acrylate having a polyether skeleton, and urethane (meth) acrylic having a polyester skeleton At least one selected from the group consisting of a UV curable resin composition. The UV curable resin composition according to claim 1 or 2, wherein the urethane (meth)acrylate has a weight average molecular weight of 10,000 to 100,000, and a double bond equivalent of 1,000 to 5,000 g/eq. The UV curable resin composition of claim 1 or 2, wherein the (B) UV curable polyfunctional monomer is a (meth)acrylic monomer having two or more functional groups. The UV curable resin composition according to claim 1 or 2, wherein the acylphosphine oxide-based photopolymerization initiator is 2,4,6-trimethylbenzoyldiphenylphosphine oxide. The UV curable resin composition according to claim 1 or 2, wherein the (D) silane coupling agent is a silane coupling agent having a (meth)acrylic group. An adhesive sheet comprising the UV curable resin composition according to claim 1 or 2. The adhesive sheet according to claim 7, wherein the film thickness after drying is 10 to 250 µm. It is a 3D liquid crystal panel in which an LCD and a patterning retarder are laminated.
A 3D liquid crystal panel in which the LCD and the retardation plate are adhered by the adhesive sheet according to claim 7 . The 3D liquid crystal panel according to claim 9, wherein the patterning retardation plate is a patterned glass plate. delete