JP6704013B2 - Double-sided adhesive sheet, 3D liquid crystal panel and manufacturing method thereof - Google Patents

Description

The present invention relates to a double-sided adhesive sheet, a 3D liquid crystal panel and a method for manufacturing the same.

At present, liquid crystal displays (LCDs) are becoming very common display devices with the spread of digitized electronic devices, such as liquid crystal televisions, PC displays, mobile phone terminals, portable game consoles, calculators, and watches. It is used as the display of various devices. In particular, in recent years, there is an LCD in which a retardation plate made of glass (hereinafter, simply referred to as “retardation plate”) is adhered to an LCD for the purpose of imparting a 3D function, for example. Here, the LCD to which the retardation film is adhered may be collected after use and only the LCD may be reused. For example, it is required to peel off the retardation plate from the LCD and rework the LCD. At this time, in the conventional method, a method of cooling the entire LCD (in other words, cooling the adhesive) and peeling the retardation plate from the LCD is adopted. However, this method requires equipment for cooling and is not good in workability. Further, since both the retardation plate and the LCD have rigidity, there is a problem that one of them is damaged when peeled. That is, in the conventional adhesive sheet, it is difficult to easily peel off the LCD and the retardation film at room temperature to rework the LCD after the LCD and the retardation film are adhered.

In order to solve such a problem, an adhesive sheet that can be easily peeled off at room temperature, even if the adherend is hard such as glass, has been studied. For example, Patent Document 1 proposes a pressure-sensitive adhesive material having an internal peeling interface inside a pressure-sensitive adhesive layer. Patent Document 1 describes that this adhesive material makes it possible to achieve both reworkability and reliability on the adhesive surface such as occurrence of peeling or foaming.

Japanese Patent No. 5514817

The pressure-sensitive adhesive described in Patent Document 1 includes a pressure-sensitive adhesive having two or more layers, and an internal peeling interface is provided inside the pressure-sensitive adhesive. However, the pressure-sensitive adhesive of the same document does not involve an intentional chemical reaction before and after being attached to various adherends (in other words, the state change of the pressure-sensitive adhesive is unlikely to occur), and therefore the pressure-sensitive adhesive is used as a retardation plate or When it is attached to the LCD, the conformability to the irregularities on the surface of each adherend is not sufficient, which causes display unevenness. On the other hand, it is conceivable to lower the melt viscosity of the pressure-sensitive adhesive in order to prevent display unevenness, but in this case, the adhesive strength becomes too strong and rework becomes difficult. Further, when the melt viscosity is significantly reduced, the fluidity becomes too high and the cohesive force is insufficient, the holding power with various adherends and the adhesive force are impaired, and the reliability cannot be maintained especially in a high temperature environment. The problem arises.

In view of the above circumstances, according to the present invention, it is possible to peel off an adherend without damaging the adherend (for example, it is possible to peel off the adherend without damaging the adherend even at room temperature). It is possible to provide a double-sided adhesive sheet, a 3D liquid crystal panel, and a method for manufacturing the same, which are possible and have excellent reliability and bondability.

As a result of intensive studies to solve the above problems, the present inventors have found that a double-sided adhesive sheet having a specific structure and physical properties can solve the above problems, and have completed the present invention.

That is, the present invention is as follows.
(1)
A transparent film substrate, a UV-curable first adhesive layer laminated on one surface of the transparent film substrate, and a UV-curable second adhesive layer laminated on the other surface of the transparent film substrate. And an adhesive layer of
The first adhesive layer and the second adhesive layer include a urethane (meth)acrylate that is a UV-curable prepolymer and a photopolymerization initiator, and the light for 100 parts by mass of the urethane (meth)acrylate is used. The content of the polymerization initiator is 0.5 parts by mass or more,
The melt viscosity of each of the first adhesive layer and the second adhesive layer at 50° C. before UV curing is 1.0×10 ^{5 to} 3.0×10 ⁶ poise, and 50° C. to 100° C. Double-sided adhesive sheet having a melt viscosity change rate of 75 to 95%.
(2)
The transparent film substrate is the double-sided adhesive sheet according to (1), which is not subjected to a mold release treatment.
(3)
The double-sided adhesive sheet according to (1) or (2), wherein each of the first adhesive layer and the second adhesive layer has a thickness of 10 to 75 μm.
(4)
The second adhesive layer is the double-sided adhesive sheet according to any one of (1) to (3), which further contains a UV-curable polyfunctional monomer.
(5)
In the second adhesive layer, the double-sided adhesive sheet according to (4), wherein the content of the UV curable polyfunctional monomer is 15 to 60 parts by mass relative to 100 parts by mass of the urethane (meth)acrylate.
(6)
The weight average molecular weight of the urethane (meth)acrylate is 10,000 to 120,000, and the double bond equivalent of the urethane (meth)acrylate is 1,000 to 5,000 g/eq (1) to ( The double-sided adhesive sheet according to any one of 5).
(7)
The photopolymerization initiator is a double-sided adhesive sheet according to any one of (1) to (6), which is an acylphosphine oxide-based photopolymerization initiator.
(8)
The UV curable polyfunctional monomer is the double-sided adhesive sheet according to any one of (4) to (7), which is a (meth)acrylic monomer having two or more functional groups.
(9)
A patterning retardation glass plate, a liquid crystal display, and the double-sided adhesive sheet according to any one of (1) to (8), which adheres the patterning retardation glass plate and the liquid crystal display,
A 3D liquid crystal panel in which the first adhesive layer is arranged on the patterned retardation glass plate side, and the second adhesive layer is arranged on the liquid crystal display side.
(10)
The 180° peel strength between the first adhesive layer after UV curing and the patterned retardation glass plate is 400 mN/25 mm or more, and the first adhesive layer after UV curing, The 3D liquid crystal panel of (9), wherein the 180° peel strength between the transparent film substrate and the transparent film substrate is 400 mN/25 mm or more.
(11)
The 180° peel strength between the second adhesive layer after UV curing and the transparent film substrate is 50 to 200 mN/25 mm, and the second adhesive layer after UV curing and the liquid crystal display. The 3D liquid crystal panel according to (9) or (10), which has a 180° peel strength of 400 mN/25 mm or more.
(12)
A method for manufacturing a 3D liquid crystal panel using the double-sided adhesive sheet according to any one of (1) to (8),
A method for manufacturing, comprising a step of bonding the double-sided adhesive sheet in a UV uncured state between a patterning retardation glass plate and a liquid crystal display, and then performing UV curing.

According to the present invention, the adherend can be peeled off without being damaged (for example, the adherend can be peeled off at room temperature without being damaged), so that the adherend can be reworked. Therefore, it is possible to provide a double-sided adhesive sheet having excellent reliability and bondability, a 3D liquid crystal panel, and a method for manufacturing the same.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. It should be noted that the present invention is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist thereof.

[Double-sided adhesive sheet]
The double-sided adhesive sheet in the present embodiment has a transparent film substrate, a UV-curable first adhesive layer laminated on one surface of the transparent film substrate, and the other surface of the transparent film substrate. A laminated UV-curable second adhesive layer, wherein the first adhesive layer and the second adhesive layer are urethane (meth)acrylate that is a UV-curable prepolymer, and photopolymerization. And a content of the photopolymerization initiator with respect to 100 parts by mass of the urethane (meth)acrylate is 0.5 parts by mass or more, and each of the first adhesive layer and the second adhesive layer. The melt viscosity at 50° C. before UV curing is 1.0×10 ^{5 to} 3.0×10 ⁶ poise, and the melt viscosity change rate from 50° C. to 100° C. is 75 to 95%. The double-sided adhesive sheet of the present embodiment is capable of reworking the adherend because it has the above-mentioned configuration and can be peeled off without damaging the adherend, and has excellent reliability and bonding. Have sex. The double-sided adhesive sheet of the present embodiment can easily peel off the LCD from the adherend for rework even at room temperature, and can provide good reliability.

The double-sided adhesive sheet in the present embodiment has a structure of three or more layers including a transparent film substrate and two kinds of adhesive layers, and the first adhesive layer is provided on one surface of the transparent film substrate. However, the second adhesive layer is laminated on the other surface.

[Transparent film substrate]
The material forming the transparent film substrate is not particularly limited, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyurethane polypropylene, polycarbonate, triacetyl cellulose, polyvinyl alcohol, polystyrene and the like. These materials may be used alone or in combination of two or more. Among the above, the material is preferably one or more selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and polyethylene from the viewpoint of reliability and releasability, and more preferably polyethylene terephthalate.

The thickness of the transparent film substrate is preferably 10 to 100 μm, more preferably 25 to 75 μm. When the thickness is 100 μm or less, for example, the image quality of the image tends to be better, and the viewing angle of the 3D image tends to be more sufficiently secured. When the thickness is 10 μm or more, the handling property is better Tends to be.

Since the double-sided adhesive sheet of the present embodiment is excellent in the releasing property of the first adhesive layer and the second adhesive layer, the transparent film substrate is sufficiently released even if the releasing treatment is not performed. Has type. On the other hand, when the transparent film substrate is subjected to the mold release treatment, the mold release property is further excellent as compared with the case where the mold release treatment is not performed. Examples of the release treatment at this time include treatments with alkyd, silicone, unsaturated polyester, polyolefin, wax and the like.

[Adhesive layer]
The double-sided adhesive sheet in the present embodiment includes a first adhesive layer laminated on one surface of the transparent film substrate and a second adhesive layer laminated on the other surface. The first adhesive layer and the second adhesive layer each include (A) a urethane (meth)acrylate (hereinafter, also referred to as “(A) component”) that is a UV-curable prepolymer (B) light. A polymerization initiator (hereinafter, also referred to as “component (B)”). From the viewpoint that the second adhesive layer can adjust the peel strength at the interface between the second adhesive layer and the transparent film base material to a more appropriate range in addition to the components (A) and (B), Furthermore, it is preferable to include (C) a UV-curable polyfunctional monomer (hereinafter, also referred to as “component (C)”).

The first adhesive layer and the second adhesive layer included in the double-sided adhesive sheet of the present embodiment have a melt viscosity at 50° C. before UV curing of 1.0×10 ^{5 to} 3.0×10 ⁶ poise. And the change rate of melt viscosity from 50° C. to 100° C. before UV curing is 75 to 95%. When the melt viscosity is within the above range, the conformability to irregularities on the surface of various adherends at the time of bonding becomes good, and the bondability is excellent. Further, when the rate of change in melt viscosity from 50° C. to 100° C. is within the above range, the ability to follow the irregularities on the surface of various adherends is maintained even after bonding and the LCD is lit and displayed. It is possible to suppress the display unevenness and to prevent the occurrence of 3D shift when a 3D image is displayed, for example. Here, the "3D shift" means that when the patterning phase difference glass plate and the LCD are aligned so that they can be displayed in 3D, and when the bonding is performed by an autoclave process, the fluidity is too high and the position shift occurs. A phenomenon in which 3D display is disabled.

The melt viscosity change rate from 50° C. to 100° C. before UV curing of the first and second adhesive layers is more preferably 80 to 90%. Here, the melt viscosity can be measured according to the method described in Examples described later, and the melt viscosity change rate means a value calculated according to the following formula (1).

Melt viscosity change rate =
(Melt viscosity at 50° C.−melt viscosity at 100° C.)/(melt viscosity at 50° C.)×100 (1)

The rate of change in melt viscosity can be adjusted by, for example, changing the molecular weight of the (A) UV-curable prepolymer and the addition amount of the (C) UV-curable polyfunctional monomer.

<(A) component>
The urethane (meth)acrylate as the (A) UV-curable prepolymer means a prepolymer having a urethane structure in the main chain and a (meth)acrylic group in the side chain. The urethane (meth)acrylate is not particularly limited, and examples thereof include urethane (meth)acrylate having a polycarbonate skeleton, urethane (meth)acrylate having a polyether skeleton, urethane (meth)acrylate having a polyester skeleton, and the like. Among them, urethane (meth)acrylate having a polycarbonate skeleton is preferable from the viewpoint of preventing the cured adhesive sheet from yellowing.

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

The weight average molecular weight of the polycarbonate diol is preferably 170 to 1,000, more preferably 300 to 700, and further preferably 400 to 600. When the weight average molecular weight of the polycarbonate diol is within the above range, the urethane prepolymer main chain tends to have the film property required for rework.

The diisocyanate is not particularly limited, and examples thereof include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and 4,4′-diphenylmethane diisocyanate (4 , 4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI ), 1,5-naphthalene diisocyanate (NDI) and other aromatic isocyanates; hexamethylene isocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanatomethyl (NBDI) and other aliphatic polyisocyanates; Examples thereof include alicyclic polyisocyanates such as transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), and H6XDI (hydrogenated XDI). Diisocyanates are preferred.

The carboxylic acid diol is not particularly limited, and examples thereof include dimethylolbutanoic acid and dimethylolpropionic acid.

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 a urethane (meth) having a polyester skeleton. )Acrylate refers to a prepolymer having a polyester structure and a urethane structure in the main chain and a (meth)acrylic group in the side chain. These prepolymers can be obtained by the same method as that for the urethane (meth)acrylate having a polycarbonate skeleton, except that polyether diol and polyester diol are used instead of the polycarbonate diol, respectively. At this time, the preferable numerical range of the weight average molecular weight of each of the polyether diol and the polyester diol includes the preferable numerical range of the weight average molecular weight of the above-mentioned polycarbonate diol.

The weight average molecular weight of the component (A) is preferably 10,000 to 120,000, more preferably 30,000 to 70,000, and further preferably 40,000 to 60,000. When the weight average molecular weight of the component (A) is within the above range, film-forming property and curability are improved, and reliability (for example, long-term reliability) tends to be further improved. Here, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) using standard polystyrene having an average molecular weight of about 500 to about 1,000,000.

The double bond equivalent of the component (A) is preferably 1,000 to 5,000 g/eq, more preferably 1,500 to 2,500 g/eq, and further preferably 1,800 to 2,200 g. /Eq. When the double bond equivalent of the component (A) is within the above range, the effect of curing shrinkage is small, the reliability (for example, long-term reliability) is further excellent, the curing becomes easier, and the reworking becomes easier. Tends to become. Here, the double bond equivalent means 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.

The glass transition temperature (Tg) of the component (A) is preferably -10 to 20°C, more preferably -5 to 15°C, and further preferably 0 to 10°C. When the glass transition temperature is within the above range, the balance between reliability (for example, long-term reliability) and reworkability tends to be better. Here, the glass transition temperature refers to a value measured by dynamic viscoelasticity measurement (DMA).

<(B) component>
The photopolymerization initiator (B) is not particularly limited, and examples thereof include an acylphosphine oxide photopolymerization initiator, an alkylphenone photopolymerization initiator, and an intramolecular hydrogen abstraction type photopolymerization initiator. These photopolymerization initiators may be used alone or in combination of two or more. Among these, the acylphosphine oxide-based photopolymerization initiator is preferable from the viewpoint of reactivity and uniformity of curing. Specific examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoylphenylphosphine oxide, 2,2-dimethoxy-1,2-diphenylethan-1-one, and phenylglyoxylic acid methyl. Esters and the like can be mentioned. Among these, 2,4,6-trimethylbenzoylphenylphosphine oxide is preferable from the viewpoints of higher radical generation efficiency and more excellent deep-part curability.

<(C) component>
The second adhesive layer in the present embodiment preferably contains (C) a UV-curable polyfunctional monomer in addition to the components (A) and (B). In order to enable reworking of the LCD, it is necessary to increase the viscoelasticity at room temperature, but by further adding a UV curable polyfunctional monomer to the UV curable prepolymer, the second adhesive layer of the second adhesive layer can be formed. The crosslink density after curing can be further increased, and the viscoelasticity at room temperature can be further increased.

The component (C) is not particularly limited as long as it is a monomer having two or more functional groups, and examples thereof include (meth)acrylic monomers. Among them, from the viewpoint of increasing crosslink density and improving reworkability, (Meth)acrylic monomers having two or more functional groups are preferred.

As the component (C), specifically, as monomers having two functional groups, 1,4-butanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, glycerin di(meth)acrylate, and tri- Cyclodecane dimethanol diacrylate may be mentioned, and examples of the monomer having three functional groups may include trimethylolpropane triacrylate, trimethylolmethane tri(meth)acrylate, and trimethylolpropane propylene oxide-modified tri(meth)acrylate. Examples of the monomer having four functional groups include dipentaerythritol tetra(meth)acrylate, pentaerythritol ethylene oxide modified tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol ethylene oxide modified tetra(meth)acrylate and ditrierythritol ethylene oxide. Methylolpropane tetra(meth)acrylate, dipentaerythritol hexaacrylate and the like can be mentioned. Among these, a (meth)acrylic monomer having 4 or more functional groups is more preferable, and dipentaerythritol hexaacrylate having 6 functional groups is further preferable, from the viewpoint of further excellent reworkability.

The content of the component (B) with respect to 100 parts by mass of the component (A) contained in each of the first adhesive layer and the second adhesive layer is 0.5 parts by mass or more, and preferably 1. It is 0 part by mass or more, and more preferably 1.5 parts by mass or more. When the content of the component (B) is 0.5 parts by mass or more, curing reactivity becomes good, and reworkability and reliability (for example, long-term reliability) are improved. The upper limit of the content of the component (B) is not particularly limited, but if it is too large, the optical properties tend to deteriorate, so it is preferably 7.0 parts by mass or less.

The content of the component (C) with respect to 100 parts by mass of the component (A) contained in the second adhesive layer is preferably 15 to 60 parts by mass, more preferably 18 to 40 parts by mass, and further preferably 20 to 30 parts by mass. If the content of the component (C) is 15 parts by mass or more, the reworkability at room temperature tends to be better, and if it is 60 parts by mass or less, the adhesiveness becomes more sufficient and reliability (for example, Long-term reliability) tends to be even better. Further, when the content of the component (C) with respect to 100 parts by mass of the component (A) is adjusted within the above range, the melt viscosity of the resin composition forming the second adhesive layer is kept within a certain range. However, there is an advantage that uneven bonding and image distortion are less likely to occur. In addition, the mass part in the said content means the mass part in solid content conversion.

<(D) Silane coupling agent>
The adhesive layer of the double-sided adhesive sheet in the present embodiment further contains (D) a silane coupling agent (hereinafter, also referred to as “(D) component”) in addition to the above components (A) to (C). You may stay. In particular, when the second adhesive layer has high viscoelasticity, the adhesiveness with the adherend tends to decrease, but when the second adhesive layer contains a silane coupling agent, the adhesive force is maintained, and particularly when the adherend is glass. The reliability (for example, long-term reliability) of the plate tends to be further improved.

The component (D) is not particularly limited, and for example, any silane coupling agent such as a monomer type silane coupling agent, an alkoxy oligomer type silane coupling agent, or a polyfunctional type silane coupling agent can be used. Among them, a silane coupling agent having a (meth)acryl group is preferable, and 3-acryloxypropyltrimethoxysilane is more preferable, from the viewpoint of improving adhesiveness when the adherend is glass and maintaining long-term reliability. preferable.

The content of the component (D) with respect to 100 parts by mass of the component (A) is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3.0 parts by mass, and further preferably 0.5. Is about 1.5 parts by mass. When the content of the component (D) is within the above range, the balance between long-term reliability and reworkability tends to be better.

<Other ingredients>
In the adhesive layer in 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. It may contain additives usually added to the adhesive, such as an agent, a leveling agent, an antifoaming agent, a color pigment, an organic solvent and the like.

The method for producing the double-sided adhesive sheet in the present embodiment is not particularly limited, and for example, after coating the resin composition forming the first adhesive layer on the transparent film substrate and drying the same, the other surface is also coated. A double-sided adhesive sheet having an adhesive layer on both sides can be obtained by applying the resin composition constituting the second adhesive layer and drying it. In particular, it is preferable that the resin composition forming the adhesive layer is made into a varnish using an organic solvent, then applied onto a transparent film substrate, and dried. The organic solvent used at this time is not particularly limited, and examples thereof include toluene, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether, and dimethyl acetamide. These organic solvents may be used alone or in combination of two or more. Among these, methyl ethyl ketone is preferable from the viewpoint of solubility. The content of the organic solvent in the varnish is preferably 30 to 90 parts by mass, more preferably 40 to 70 parts by mass, relative to 100 parts by mass of the component (A).

As a method of coating the resin composition on the transparent substrate film, a comma coater, a die coater, a gravure coater, or the like can be appropriately adopted depending on the coating thickness. The resin composition can be dried by an in-line dryer or the like, and the drying conditions at that time can be appropriately adjusted depending on the type and amount of each component.

The thickness of each layer of the first adhesive layer and the second adhesive layer is preferably 10 to 75 μm, more preferably 20 to 60 μm, and further preferably 30 to 50 μm. In addition, the thickness here means the thickness after drying. When the thickness is 10 μm or more, the adhesiveness is further improved, and the reliability (for example, long-term reliability) tends to be further improved. “Long-term reliability” specifically means that the adhesion between the LCD and the patterning retardation glass plate is good, so that the deviation is unlikely to occur, and as a result the observer can observe a good 3D image. Including that. On the other hand, when the thickness of the first and second adhesive layers is 75 μm or less, the distance between the LCD and the patterning phase difference glass plate becomes appropriate, and a proper viewing angle is secured when viewing a 3D image. Tends to be able to.

The double-sided adhesive sheet in the present embodiment may be further provided with a protective film outside each layer of the first adhesive layer and the second adhesive layer. The protective film is not particularly limited, and examples thereof include a film made of one or more resins selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. Among these, a film made of polyethylene terephthalate resin is preferable from the viewpoint of reducing the manufacturing cost.

The protective film may be subjected to a release treatment on the surface laminated with the adhesive layer. By subjecting the protective film to the mold release treatment, the protective film can be easily peeled off during use, so that the handleability is improved. The release treatment is not particularly limited, and examples thereof include a release agent such as a silicone-based release agent, a fluorine-based release agent, a long-chain alkyl graft polymer-based release agent, and a method of surface-treating by plasma treatment. Can be used.

[3D LCD panel]
The 3D liquid crystal panel in the present embodiment includes the patterning retardation glass plate and the double-sided adhesive sheet of the present embodiment in which a liquid crystal display (LCD) is attached, and the first adhesive layer has the patterning position. The second adhesive layer is arranged on the retardation glass plate side, and the second adhesive layer is arranged on the liquid crystal display side.

The 3D liquid crystal panel in the present embodiment is a transparent film substrate without damaging the patterning retardation glass plate or the LCD by bonding the patterning retardation glass plate and the LCD using the double-sided adhesive sheet described above. And can be easily peeled off at the interface between the second adhesive layer and. The LCD can then be reused by peeling it off from the second adhesive layer.

The first adhesive layer has a storage elastic modulus at room temperature (25° C.) of preferably 1.0×10 ^{5 to} 1.0×10 ⁸ Pa after UV curing, more preferably 5.0×10 5. ^{It is 5 to} 5.0×10 ⁷ Pa, and more preferably 1.0×10 ^{6 to} 1.0×10 ⁷ Pa. When the storage elastic modulus of the first adhesive layer is in the above range, the reliability tends to be further improved especially in a high temperature and high humidity environment. The second adhesive layer has a storage elastic modulus at room temperature (25° C.) of preferably 1.0×10 ^{8 to} 1.0×10 ¹⁰ Pa after UV curing, and more preferably 5.0×10 5. ^{It is 8 to} 5.0×10 ⁹ Pa, and more preferably 8.0×10 ^{8 to} 2.0×10 ⁹ Pa. When the storage elastic modulus of the second adhesive layer is 1.0×10 ⁸ or more, the adhesive force with the transparent film base material becomes more appropriate, and the reworkability tends to be further improved. On the other hand, when the storage elastic modulus of the second pressure-sensitive adhesive layer is 1.0×10 ¹⁰ Pa or less, the reliability tends to be further improved especially in a high temperature and high humidity environment.

The viscoelasticity of the adhesive layer can be measured by dynamic viscoelasticity measurement (DMA), and more specifically, it can be measured according to the method described in Examples below.

The peeling strength at the interface between the layers is 180° peeling strength between the first adhesive layer and the patterned retardation glass plate after UV curing is 400 mN/25 mm or more from the viewpoint of the balance between reworkability and reliability. It is preferable that the peel strength between the first adhesive layer and the transparent film substrate after UV curing is 400 mN/25 mm or more (180° direction). On the other hand, the 180° peel strength between the second adhesive layer after UV curing and the transparent film substrate is 50 mN/25 mm or more and 200 mN/25 mm or less (180° direction), and the second adhesion after UV curing The peel strength between the agent layer and the LCD is preferably 400 mN/25 mm or more. The 180° peeling strength is obtained by the method described in Examples described later.

The double-sided adhesive sheet according to the present embodiment can be used not only for the purpose of a 3D liquid crystal panel, but also for all purposes of reworking a display device such as an LCD or an organic EL. Examples of such applications include touch sensor panels and digital signage.

[3D Liquid Crystal Panel Manufacturing Method]
The method for manufacturing a 3D liquid crystal panel according to the present embodiment is a method for manufacturing a 3D liquid crystal panel using the double-sided adhesive sheet according to the present embodiment, in which the double-sided adhesive sheet is patterned in a UV uncured state with a retardation glass plate and a liquid crystal display. And a step of UV-curing the film after bonding it to the substrate. As a specific example of this step, a double-sided adhesive sheet is attached to a patterned retardation glass plate, LCD is then attached, and then UV irradiation is performed to cure the double-sided adhesive sheet by UV. UV irradiation conditions are not particularly limited.

In addition, each physical property and the like in the present embodiment can be measured according to the methods described in the following examples unless otherwise specified.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The components and materials used in the examples and comparative examples are as follows.
[Component (A): UV curable prepolymer]
UV curable prepolymers (a) to (h) were produced according to the following Synthesis Examples 1 to 7 and Comparative Synthesis Example 1.

[Component (B): Photopolymerization Initiator]
(1) Photopolymerization initiator (a)
2,4,6-Trimethylbenzoylphenylphosphine oxide manufactured by BASF, trade name “Irgacure TPO”, acylphosphine oxide photopolymerization initiator (2) photopolymerization initiator (b)
2,2-dimethoxy-1,2-diphenylethan-1-one manufactured by BASF, trade name "Irgacure 651", alkylphenone photopolymerization initiator (3) photopolymerization initiator (c)
Phenylglyoxylic acid methyl ester manufactured by BASF, trade name "Irgacure MBF", intramolecular hydrogen abstraction type photopolymerization initiator

[Component (C): UV-curable polyfunctional monomer]
(1) UV curable polyfunctional monomer (a)
Dipentaerythritol hexaacrylate manufactured by Daicel Ornex, product name "DPHA"
(2) UV curable polyfunctional monomer (b)
Tricyclodecane dimethanol diacrylate manufactured by Daicel Ornex, product name "IRR214-K"
(3) UV curable polyfunctional monomer (c)
Trimethylolpropane triacrylate manufactured by Daicel Ornex, product name "TMPTA"

[Other ingredients]
Adhesive manufactured by 3M, product name "Optically Clear Adhesive 81"
46"

The evaluation method and measurement method of each physical property are as follows.

[Reworkability]
(1) Sample preparation procedure The release PET film on the adhesive layer (A) side of the double-sided adhesive sheet was peeled off, laminated on a patterning retardation glass plate (0.7 t, 19 inches) by lamination, and autoclaved. .. Lamination is performed using a roll laminate at a lamin roll temperature of 25 to 40° C., a lamin roll linear pressure of 1.0 to 2.0 kgf/cm, and a lamin roll speed of 0.3 to 2.0 m/min. It was carried out at 0.6 MPa for 10 minutes. Next, the release PET film on the adhesive layer (B) side was peeled off, the LCD and the LCD were bonded together by vacuum laminating, and autoclave treatment was performed again, followed by UV exposure to obtain a test sample. The vacuum lamination was performed at a temperature of 25 to 50° C., a pressure of 0.01 to 0.05 MPa, a vacuuming time of 60 seconds, and a pressurizing time of 30 seconds. The autoclave was carried out at a temperature of 60° C., a pressure of 0.6 MPa and a time of 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .
(2) Measuring method The test sample was inserted at the interface between the untreated PET film and the adhesive layer (B) at room temperature, and then scraped open, and evaluated according to the following.
⊚: The adherend could be easily reworked without being damaged. ◯: The adherend could be reworked without being damaged. x: The adherend was damaged and difficult to rework.

[reliability]
(1) Sample preparation procedure A test sample was prepared by the same procedure as the reworkability.
(2) Measuring method The test sample was left standing in a moist heat device. The conditions were a temperature of 50° C., a humidity of 80% and a time of 240 hours. Then, it was left at room temperature for 24 hours. The presence or absence of deviation, floating, or foaming of the glass bonding position as compared with the time of starting to stand in the humid heat device was visually observed and evaluated according to the following.
◯: Glass misalignment, floating, or foaming did not occur ×: Glass misalignment, floating, or foaming occurred

[Pasteability]
(1) Sample preparation procedure A test sample was prepared by the same procedure as the reworkability.
(2) Measurement method The display of the test sample was turned on and visually evaluated according to the following.
◯: No sticking unevenness or 3D shift occurred in the displayed image (no double image was generated)
X: Lamination unevenness and 3D shift occurred in the display image (double image was generated)

[optical properties]
(1) Sample preparation procedure The release PET film on the adhesive layer (A) side of the double-sided adhesive sheet was peeled off, and laminated on an optical glass (40 mm square) by vacuum lamination. The vacuum lamination was performed at a temperature of 25 to 50° C., a pressure of 0.01 to 0.05 MPa, a vacuuming time of 60 seconds, and a pressurizing time of 30 seconds. Next, the release PET film on the adhesive layer (B) side was peeled off and adhered to an optical glass (40 mm square) under the same conditions as the above vacuum lamination conditions, and then autoclave treatment was carried out, followed by UV exposure for testing. I got a sample. The autoclave was carried out at a temperature of 60° C., a pressure of 0.6 MPa and a time of 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .
The yellow index (YI) of the test sample was measured using a spectrophotometer (U-4100 manufactured by Hitachi High Technology). The measurement conditions were C light source, transmission, and wavelength λ=380 to 760 nm.
◎: YI value less than 1.5 ○: YI value of 1.5 or more and less than 2 ×: YI value of 2 or more

[Melt viscosity]
(1) Sample preparation procedure Resin compositions (A) and (B) were applied to both sides of a 25 μm release PET so that the thickness after drying was 50 μm, and dried at 130° C. for 5 minutes. A 25 μm release PET was placed on the opposite surface to prepare a double-sided adhesive sheet.
The release PET of the adhesive sheet produced above was peeled off, and 20 double-sided adhesive sheets were stuck together to produce an adhesive sheet having a thickness of 1.0 mm. At this time, the lamination was performed by roll lamination at a lamin roll temperature of 25 to 40° C., a lamin roll linear pressure of 1.0 to 2.0 kgf/cm, and a lamin roll speed of 0.3 to 2.0 m/min.
(2) Measuring method Melt viscosity was measured using a dynamic viscoelasticity measuring device (Rheosol-G3000 manufactured by UBM Co., Ltd.). The measurement conditions were a temperature rising rate of 5.0° C./min in a temperature range of 30 to 130° C., a fundamental frequency of 1 Hz, strain control of 0.12 deg, and load control of 300 g. The melt viscosities at 50° C. and 100° C. were measured, and the rate of change in melt viscosity when the temperature was raised from 50° C. to 100° C. was calculated with the value of the melt viscosity at 50° C. as 100.

[Peel strength]
(1) Sample preparation procedure (1-1) Peel strength between the adhesive layer A and the patterned retardation glass plate The release PET film on the adhesive layer A side of the double-sided adhesive sheet was peeled off, and the patterned retardation glass plate was peeled off. After laminating, autoclaving, and UV exposure were applied. The laminate is a roll laminate with a lamin roll temperature of 25 to 30° C., a lamin roll linear pressure of 1.0 to 2.0 kgf/cm, a lamin roll speed of 0.3 to 2.0 m/min, an autoclave temperature of 60° C., a pressure of 0.6 MPa, It was carried out for 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .
(1-2) Peel Strength between Adhesive Layer A and Transparent Film Substrate The release PET film on the adhesive layer A side of the double-sided adhesive sheet is peeled off and subjected to an easy-adhesion treatment PET (Toyobo PETA 4300#). 100) by laminating, autoclaving, and curing with a UV exposure machine. The laminate is a roll laminate with a lamin roll temperature of 25 to 30° C., a lamin roll linear pressure of 1.0 to 2.0 kgf/cm, a lamin roll speed of 0.3 to 2.0 m/min, an autoclave temperature of 60° C., a pressure of 0.6 MPa, It was carried out for 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .
(1-3) Peel strength between adhesive layer B and transparent film base material The release PET film on the adhesive layer B side of the double-sided adhesive sheet was peeled off and subjected to an easy-adhesion treatment (PETA4300# manufactured by Toyobo). 100) by laminating, autoclaving, and curing with a UV exposure machine. The laminate is a roll laminate, the lamin roll temperature is 25 to 30° C., the lamin roll linear pressure is 1.0 to 2.0 kgf/cm, the lamin roll speed is 0.3 to 2.0 m/min, the autoclave temperature is 60° C., the pressure is 0.6 MPa, It was carried out for 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .
(1-4) Peel strength between adhesive layer B and LCD The release PET film on the adhesive layer B side of the double-sided adhesive sheet was peeled off, laminated on an LCD panel by vacuum lamination, and autoclaved, and then UV. It was cured by an exposure machine. The vacuum lamination was performed at a temperature of 25 to 50° C., a pressure of 0.01 to 0.05 MPa, a vacuuming time of 60 seconds, and a pressurizing time of 30 seconds. The autoclave was carried out at a temperature of 60° C., a pressure of 0.6 MPa and a time of 1 hour. The UV exposure was performed using an ultrahigh pressure mercury lamp light source so that the integrated light amount would be 3000 mJ/cm ² .

(2) Measurement method (2-1) Peel strength between adhesive layer A and patterned retardation glass plate The sample prepared in (1-1) above was cut into a width of 25 mm, and the double-sided adhesive sheet was rotated in the 180° direction. The peel strength when peeled off was measured. At this time, the peeling speed was measured at 300 m/min.
(2-2) Peel strength between adhesive layer A and transparent film substrate When the sample prepared in (1-2) was cut into a width of 25 mm and the double-sided adhesive sheet was peeled off in the 180° direction. Peel strength was measured. At this time, the peeling speed was measured at 300 m/min.
(2-3) Peel strength between adhesive layer B and transparent film substrate When the sample prepared in (1-3) above was cut into a width of 25 mm and the double-sided adhesive sheet was peeled in the 180° direction. Peel strength was measured. At this time, the peeling speed was measured at 300 m/min.
(2-4) Peel strength between adhesive layer B and LCD Peel strength when the sample prepared in (1-4) above was cut into a width of 25 mm and the double-sided adhesive sheet was peeled in the 180° direction. Was measured. At this time, the peeling speed was measured at 300 m/min.

(Synthesis example 1) UV curable prepolymer (a)
In a four-necked flask equipped with a thermometer, a cooling tube, and a stirrer, 33.3 parts by mass of hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name: HDI, abbreviated name: HDI) and a polycarbonate diol having a weight average molecular weight of 400 are used. 59.4 parts by mass, 7.3 parts by mass of dimethylolbutanoic 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 the mixture was stirred at 70° C. for 24 hours. Reacted for 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 composition disappeared, and that the composition was urethane acrylate having a carboxyl group.
Next, 100 parts by mass of the obtained urethane acrylate 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. The mixture was put in, reacted at 75° C. for 12 hours, and subjected to an addition reaction to obtain a UV curable prepolymer (a).
The addition reaction was terminated when the acid value measured according to the following method became 5 mgKOH/g or less. The obtained UV curable prepolymer (a) had a weight average molecular weight of 50,000, a solid content concentration of 50% by mass, a double bond equivalent of 2,000 g/eq, and a Tg of 5°C.

(Acid value measurement method)
1 g of solid content of resin is weighed, mixed solvent (mass ratio: toluene/methanol=50/50) is added, and after dissolution, an appropriate amount of phenolphthalein solution is added as an indicator and titrated with 0.1N potassium hydroxide aqueous solution. The acid value was measured by the following formula (α).
x=10×Vf×56.1/(Wp×I) (α)
(In the formula (α), x represents an acid value (mgKOH/g), Vf represents a titration amount (mL) of a 0.1 N KOH aqueous solution, Wp represents a measured resin solution mass (g), (I indicates the measured non-volatile content in the resin solution (mass %).)

(Synthesis example 2) UV curable prepolymer (b)
Hexamethylene diisocyanate and the polycarbonate diol compound were reacted in the same manner as in Synthesis Example 1 except that the reaction was performed at 70° C. for 18 hours to obtain a UV curable prepolymer (b).
The obtained UV curable prepolymer (b) had a weight average molecular weight of 10,000, a solid content concentration of 50% by mass, a double bond equivalent of 2,000 g/eq, and a Tg of 5°C.

(Synthesis Example 3) UV curable prepolymer (c)
Hexamethylene diisocyanate and a polycarbonate diol compound were reacted in the same manner as in Synthesis Example 1 except that the reaction was carried out at 70° C. for 48 hours to obtain a UV curable prepolymer (c).
The obtained UV curable prepolymer (c) had a weight average molecular weight of 120,000, a solid content concentration of 50% by mass, a double bond equivalent of 2,000 g/eq, and a Tg of 5°C.

(Synthesis example 4) UV curable prepolymer (d)
A UV curable prepolymer (d) was obtained in the same manner as in Synthesis Example 1 except that polyether diol was used instead of polycarbonate diol.
The obtained UV curable prepolymer (d) had a weight average molecular weight of 50,000, a solid content concentration of 50%, a double bond equivalent of 2,000 g/eq, and a Tg of 0°C.

(Synthesis example 5) UV curable prepolymer (e)
A UV curable prepolymer (e) was obtained by the same method as in Synthesis Example 1 except that polyester diol was used instead of polycarbonate diol.
The obtained UV curable prepolymer (b) had a weight average molecular weight of 50,000, a solid content concentration of 50%, a double bond equivalent of 2,000 g/eq, and a Tg of 0°C.

(Synthesis example 6) UV curable prepolymer (f)
Hexamethylene diisocyanate and the polycarbonate diol compound were reacted in the same manner as in Synthesis Example 1 except that the reaction was carried out at 70° C. for 12 hours to obtain a UV curable prepolymer (f).
The obtained UV curable prepolymer (f) had a weight average molecular weight of 5,000, a solid content concentration of 50% by mass, a double bond equivalent of 2,000 g/eq, and a Tg of 5°C.

(Synthesis example 7) UV curable prepolymer (g)
Hexamethylene diisocyanate and the polycarbonate diol compound were reacted in the same manner as in Synthesis Example 1 except that the reaction was carried out at 70° C. for 56 hours to obtain a UV curable prepolymer (g).
The obtained UV curable prepolymer (g) had a weight average molecular weight of 150,000, a solid content concentration of 50% by mass, a double bond equivalent of 2,000 g/eq, and a Tg of 5°C.

(Comparative Synthesis Example 1) UV curable prepolymer (h)
A reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a nitrogen inlet tube was charged with 100.0 g of methoxypropanol propylene glycol monomethyl ether (PGM) as a polymerization solvent, and the temperature was raised to 80° C. with 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 were mixed in advance at 80° C. The mixture was added dropwise from the dropping funnel over 3 hours while keeping it warm. After completion of the dropping, the reaction solution was heated to 90° C. with stirring, and further stirred for 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 into a reaction vessel, and 100 A UV-curable prepolymer (h) was obtained by carrying out a reaction at 12° C. for 12 hours and carrying out an addition reaction.
The addition reaction was terminated when the acid value became 5 mgKOH/g or less. Further, the obtained UV curable prepolymer (h) had a weight average molecular weight of 45,000, a solid content concentration of 47 mass% and a Tg of 3°C.

(Example 1)
(1) Preparation of UV curable resin composition In a reaction vessel, 100 parts by mass of UV curable prepolymer (a) was added, further 0.5 part by mass of a photopolymerization initiator (a), and methyl ethyl ketone as a solvent. 140 parts by mass was added and stirred to obtain a resin composition (A).
100 parts by mass of the UV curable prepolymer (a) was added to the reaction vessel, and further 25 parts by mass of the UV curable polyfunctional monomer (a), 1.5 parts by mass of the photopolymerization initiator (a), and a solvent. As a component, 140 parts by mass of methyl ethyl ketone was added and stirred to obtain a resin composition (B).
(2) Preparation of double-sided adhesive sheet The resin composition (A) obtained in (1) above was applied onto a 25 μm untreated PET film so that the thickness after drying would be 50 μm or more, and at 130° C. After drying for 5 minutes to form the adhesive layer (A), a 50 μm release PET film was placed on the opposite surface to obtain a single-sided adhesive sheet.
The resin composition (B) obtained in (1) above is applied onto the untreated PET film of the single-sided adhesive sheet produced above so that the thickness after drying is 50 μm or more, and the temperature is 130° C. for 5 minutes. After drying to form the adhesive layer (B), a release PET film having a thickness of 75 μm was placed to obtain a double-sided adhesive sheet.
Using the obtained double-sided adhesive sheet, reworkability, reliability, laminating property, optical property, melt viscosity and peel strength were evaluated.

(Examples 2 to 6) and (Comparative examples 1 to 5)
Forming an adhesive layer (A) using a resin composition obtained by fixing the adhesive layer (B) and changing the type and content of each component as described in Tables 1 and 2. A double-sided adhesive sheet was obtained by the same method as in Example 1 except for the above.
Using the obtained adhesive sheet, reworkability, reliability, laminating property, optical property, melt viscosity and peel strength were evaluated.

(Examples 7 to 20), (Comparative examples 6 to 11)
The adhesive layer (A) was fixed, and the adhesive layer (B) was formed using the resin composition obtained by changing the type and content of each component as described in Tables 3 to 5. A double-sided adhesive sheet was obtained by the same method as in Example 1 except for the above.
Using the obtained adhesive sheet, reworkability, reliability, laminating property, optical property, melt viscosity and peel strength were evaluated.

As shown in the above results, the double-sided adhesive sheet according to the present embodiment can easily peel off the LCD from the adherend for rework even at room temperature, and can impart good reliability and bondability. Met.

The double-sided adhesive sheet of the present invention has industrial applicability as an adhesive for liquid crystal displays and the like.

Claims (10)

A transparent film substrate, a UV-curable first adhesive layer laminated on one surface of the transparent film substrate, and a UV-curable second adhesive layer laminated on the other surface of the transparent film substrate. And an adhesive layer of
The first adhesive layer and the second adhesive layer include a urethane (meth)acrylate that is a UV-curable prepolymer and a photopolymerization initiator, and the light for 100 parts by mass of the urethane (meth)acrylate is used. The content of the polymerization initiator is 0.5 parts by mass or more,
The second adhesive layer further contains a UV-curable polyfunctional monomer, and in the second adhesive layer, the content of the UV-curable polyfunctional monomer is 100 parts by mass of the urethane (meth)acrylate. 15-60 parts by mass,
The melt viscosity of each of the first adhesive layer and the second adhesive layer at 50° C. before UV curing is 1.0×10 ^{5 to} 3.0×10 ⁶ poise, and 50° C. to 100° C. Double-sided adhesive sheet having a melt viscosity change rate of 75 to 95%. The double-sided adhesive sheet according to claim 1, wherein the transparent film substrate is not subjected to a release treatment. The double-sided adhesive sheet according to claim 1 or 2, wherein each of the first adhesive layer and the second adhesive layer has a thickness of 10 to 75 µm. The weight average molecular weight of the urethane (meth) acrylate is a 10,000～120,000 claim 1-3 double bond equivalent of the urethane (meth) acrylate is 1,000~5,000g / eq The double-sided adhesive sheet according to any one of 1. The photopolymerization initiator is, double-sided adhesive sheet according to any one of claims 1 to 4, which is an acyl phosphine oxide-based photopolymerization initiator. The UV-curable polyfunctional monomer has two or more functional groups (meth) double-sided adhesive sheet according to any one of claims 1 to 5, an acrylic monomer. It includes a patterned retardation glass plate, a liquid crystal display, and a double-sided adhesive sheet according to any one of the patterning phase difference claims 1-6, wherein the bonding the liquid crystal display and a glass plate,
A 3D liquid crystal panel in which the first adhesive layer is arranged on the patterned retardation glass plate side, and the second adhesive layer is arranged on the liquid crystal display side. The 180° peel strength between the first adhesive layer after UV curing and the patterned retardation glass plate is 400 mN/25 mm or more, and the first adhesive layer after UV curing, the The 3D liquid crystal panel according to claim 7 , wherein the 180° peel strength between the transparent film substrate and the transparent film substrate is 400 mN/25 mm or more. The 180° peel strength between the second adhesive layer after UV curing and the transparent film substrate is 50 to 200 mN/25 mm, and the second adhesive layer after UV curing and the liquid crystal display. The 3D liquid crystal panel according to claim 7 or 8 , which has a 180° peeling strength of 400 mN/25 mm or more. A method of manufacturing a 3D liquid crystal panel using a double-sided adhesive sheet according to any one of claims 1 to 6
A method for manufacturing, comprising a step of bonding the double-sided adhesive sheet in a UV uncured state between a patterning retardation glass plate and a liquid crystal display, and then UV curing.