JP5867571B2 - Resin layer and display device - Google Patents

Description

  The present invention relates to a resin layer and a display device.

In a display device in which a protective plate is laminated on a display device via a bonding resin layer, the stress generated by the shrinkage of the bonding resin layer when the bonding resin layer is cured may affect the display device. There is. When stress is applied to the display device, the following problems may occur.
The display forming material (hereinafter referred to as display material) in the display device may be affected by stress, and the display uniformity may be impaired. For example, in the case of a liquid crystal display device, the alignment of the liquid crystal sealed in the display device may be disturbed by external stress and visually recognized as display unevenness.
-When an optical film that improves display quality such as viewing angle is formed on the substrate surface on the display surface side of the display device, the optical properties of the optical film change locally due to stress, resulting in display uniformity. There is a risk of damage.

In addition, since the bonding resin layer is provided on the viewing side of the display device, the following problems may occur when bubbles exist in the cured bonding resin layer.
-The emitted light or reflected light from the display device may be disturbed by bubbles, and the image quality of the display image may be greatly impaired.
-When the display device is not displaying an image, air bubbles remaining in the bonding resin layer are easily visually recognized through the protective plate, which may greatly impair the quality of the product.
-The interfacial adhesive force between the resin layer and the display device or the interfacial adhesive force between the resin layer and the protective plate is reduced.

The following method is known as a method for manufacturing a display device having a laminated structure in which a transparent surface material is laminated on a display device.
(1) A liquid raw material is poured onto a resin protective plate and cured to form a bonding resin, or a roll sheet-shaped bonding resin is pasted in a deaerated state on a resin protective plate, and then a liquid crystal A method of laminating a cell by pressing it from one end in a deaerated state. Silicone gel is preferably used as a raw material for the bonding resin (Patent Document 1).
(2) After positioning and temporarily fixing the display panel at a predetermined position of the glass protective plate with a fixing member, a liquid resin material is injected into the space formed between the protective plate and the display panel in a reduced pressure state. And then laminating by curing. Silicone resin is preferably used as the liquid resin material (Patent Document 2).

JP-A-7-209635 JP 2006-58753 A

According to the knowledge of the present inventors, the elastic modulus of the bonding resin layer can be lowered by reducing the polarity and molecular weight of the resin forming the bonding resin layer. When the elastic modulus of the bonding resin layer interposed between the display device and the transparent surface material is lowered, the stress generated at the time of curing shrinkage is reduced and the influence on the display quality can be suppressed.
However, simply lowering the elastic modulus of the bonding resin layer may result in insufficient force for fixing the display device and the transparent surface material. For example, when the display device is installed vertically and used, the transparent surface material The display device may fall off or be detached over time.

The present invention has been made in view of the above circumstances, and when the face materials are laminated and integrated through a resin layer made of a cured product of the curable resin composition, the face materials can be sufficiently fixed to each other, and the resin It aims at providing the curable resin composition which can reduce the stress by the shrinkage | contraction at the time of hardening of a layer, and the laminated body which laminated | stacked the face material using this curable resin composition.
In addition, the present invention can sufficiently fix the face materials when the face materials are laminated and integrated through a resin layer made of a cured product of the curable resin composition, and reduces stress due to shrinkage when the resin layer is cured. An object of the present invention is to provide a method for producing a laminate, which is capable of suppressing the generation of bubbles in a resin layer.

The resin layer of the present invention has a storage shear modulus of 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa in a dynamic viscoelasticity measurement after curing, which is used for laminating a pair of face materials, and loss. A curable resin composition having a tangent of 0.01 to 0.83 , comprising a cured product of a photocurable curable resin composition containing a photocurable curable compound and a non-curable oligomer .
The curable compound preferably contains one or more oligomers having a curable group and one or more monomers having a curable group .
It is preferable that the content rate of the oligomer which has the said curable group is 20-90 mass% among the whole (100 mass%) of the said curable compound .

Display device of the present invention, while the transparent surface material of a pair of face material, the other is a display device, the storage shear modulus in a dynamic viscoelasticity measurement after curing 5 × 10 ² ~2.5 × A photocurable curable resin composition comprising 10 ⁴ Pa and a loss tangent of 0.01 to 0.83 , comprising a photocurable curable compound and a non-curable oligomer It includes a laminate in which the pair of face materials are laminated with a resin layer made of a cured product.
It is preferable that the display device is a liquid crystal display device.

According to the curable resin composition of the present invention, the pair of face materials can be sufficiently fixed by sandwiching them between the face materials and cured, and stress due to shrinkage during curing can be reduced.
According to the laminate of the present invention, the face material and the face material are sufficiently fixed via the resin layer, and the stress due to the shrinkage when the resin layer is cured is reduced.
According to the method for producing a laminate of the present invention, a pair of face materials can be sufficiently fixed through a resin layer made of a cured product of the curable resin composition of the present invention. The laminate can be produced while reducing the stress due to shrinkage and sufficiently suppressing the generation of bubbles in the resin layer.

  The laminate of the present invention is, for example, a display device. According to the manufacturing method of the present invention, the generation of bubbles in the resin layer between the display device and the protective plate is sufficiently suppressed, and the display device and the protective plate are A display device is obtained in which the resin layer is sufficiently fixed and the stress at the time of curing shrinkage is reduced, and deterioration of display quality due to the stress is prevented.

It is sectional drawing which shows an example of the display apparatus with which the display device was protected by the transparent surface material. It is a top view of the display apparatus of FIG. It is a top view which shows an example of the mode of a process (a). It is sectional drawing which shows an example of the mode of a process (a). It is a top view which shows an example of the mode of a process (b). It is sectional drawing which shows an example of the mode of a process (b). It is sectional drawing which shows an example of the mode of a process (c). It is sectional drawing which shows an example of the mode of a process (d).

In the present invention, the definition is as follows.
In the display device, a transparent surface material serving as a protective plate of the display device is referred to as a “surface material”, and the display device is referred to as a “back material”.
The surface material and the back material are collectively referred to as “face material”.
Among the face materials, in the production method of the present invention, a face material in which a liquid curable resin composition is supplied to a region where a seal portion is formed at a peripheral portion and surrounded by the seal portion is referred to as “first surface”. The face material that is superimposed on the curable resin composition is referred to as a “second face material”.
A face material having optical transparency is referred to as a “transparent face material”.
A transparent surface material made of glass is called a “glass plate”.
Hereinafter, as a preferred embodiment of the present invention, the laminate in the present invention is a display device, the pair of face materials are a surface material (transparent face material serving as a protective plate) and a back material (display device), and a seal portion The embodiment in which the curable resin composition for forming and the curable resin composition for forming the resin layer are photocurable resin compositions will be described.

<Display device>
FIG. 1 is a cross-sectional view illustrating an example of the display device of the present embodiment, and FIG. 2 is a plan view.
The display device 1 includes a transparent surface material 10 (second surface material (or first surface material)) that is a surface material and a display device 50 (first surface material (or second surface material) that is a back surface material. )), A resin layer 40 sandwiched between the transparent face material 10 and the display device 50, a seal portion 42 surrounding the resin layer 40, and a drive IC for operating the display device 50 connected to the display device 50 The flexible printed wiring board 54 (FPC) and the light shielding printing part 55 (light shielding part) formed on the peripheral edge of the transparent surface material 10 are provided.
In the display device 1, the light shielding printing part 55 is provided on the peripheral edge of the transparent surface material 10, and the area of the light transmitting part 56 surrounded by the light shielding printing part 55 is the area of the resin layer 40 surrounded by the seal part 42. The area of the transparent surface material 10 is made larger than the area of the display device 50, and the total area of the resin layer 40 and the seal portion 42 is smaller than each area of the transparent surface material 10 and the display device 50. Has been.

[Surface material]
The surface material is a transparent surface material (protective plate) that transmits the display image of the display device.
As the transparent face material, a glass plate or a transparent resin plate can be mentioned, and of course, it has high transparency with respect to emitted light and reflected light from a display device, as well as light resistance, low birefringence, high planar accuracy, and resistance to light. A glass plate is most preferable from the viewpoint of surface scratch resistance and high mechanical strength. A glass plate is also preferred from the viewpoint of sufficiently transmitting light for curing the photocurable resin composition.
Examples of the material of the glass plate include glass materials such as soda lime glass, and high transmittance glass (white plate glass) having lower iron content and less bluishness is more preferable. In order to improve safety, tempered glass may be used as a surface material.
Examples of the material of the transparent resin plate include highly transparent resin materials (such as polycarbonate and polymethyl methacrylate).

The transparent surface material may be subjected to a surface treatment in order to improve the interfacial adhesive force with the resin layer. Examples of the surface treatment method include a method of treating the surface of the transparent surface material with a silane coupling agent, and a treatment of forming a silicon oxide thin film through an oxidation flame using a frame burner.
The transparent surface material may be provided with an antireflection layer on the back surface of the joint surface with the resin layer in order to increase the contrast of the display image. The antireflection layer can be provided by a method of directly forming an inorganic thin film on the surface of the transparent surface material, or a method of bonding a transparent resin film provided with the antireflection layer to the transparent surface material.
Depending on the purpose of image display, a part or the whole of the transparent surface material is colored, light is scattered in the shape of ground glass, or light during transmission is refracted by fine irregularities on the surface. It can also be made to reflect. Moreover, what laminated | stacked the optical film etc. which perform optical modulation, such as an optical film which shows the above aspects, and a polarizing film, etc. on the transparent surface material can also be used as a transparent surface material as an integral thing.

  In the case of a glass plate, the thickness of the transparent face material is usually 0.5 to 25 mm from the viewpoint of mechanical strength and transparency. In applications such as television receivers and PC displays used indoors, 0.7 to 6 mm is preferable from the viewpoint of reducing the weight of the display device, and in public display applications installed outdoors, 3 to 20 mm is preferable. Tempered glass may be used as the transparent surface material, and chemically tempered glass can be used when the transparent surface material is thin. In the case of a transparent resin plate, 2 to 10 mm is preferable.

[Back material]
The back material is a display device.
The display device 50 in the illustrated example is an example of a liquid crystal display device having a configuration in which a transparent surface material 52 provided with a color filter and a transparent surface material 53 provided with a TFT are bonded and sandwiched between a pair of polarizing plates 51. However, the display device in the present embodiment is not limited to the illustrated example.

  In the display device, a display material whose optical state is changed by an external electric signal is sandwiched between a pair of electrodes, at least one of which is a transparent electrode. There are liquid crystal display devices, EL display devices, plasma display devices, electronic ink display devices, and the like depending on the type of display material. In addition, the display device has a structure in which a pair of face materials, at least one of which is a transparent face material, is bonded, and is arranged so that the transparent face material side is in contact with the resin layer. At this time, in some display devices, an optical film such as a polarizing plate or a retardation plate may be provided on the outermost layer side of the transparent surface material in contact with the resin layer. In this case, the resin layer is in a state of joining the optical film on the display device and the surface material.

The bonding surface with the resin layer of the display device may be subjected to a surface treatment in order to improve the interfacial adhesive force with the seal portion. The surface treatment may be performed only on the peripheral edge or on the entire surface of the face material. Examples of the surface treatment method include a treatment method using an adhesion primer or the like which can be processed at a low temperature.
The thickness of the display device is usually 0.4 to 4 mm in the case of a liquid crystal display device operated by TFT, and is usually 0.2 to 3 mm in the case of an EL display device.

[Resin layer]
The resin layer is a layer formed by curing the curable resin composition of the present invention (hereinafter also referred to as a photocurable resin composition for forming a resin layer).
The curable resin composition of the present invention (the photocurable resin composition for forming a resin layer of the present embodiment) can reduce the elastic modulus after curing, and can reduce the stress generated during curing. Therefore, adverse effects on the display performance of the display device due to such stress can be suppressed. In addition, since the viscosity of the curable resin composition when uncured is low, and thus the curable resin composition can be supplied to the surface of the face material in a short time, bubbles remain after the surface material and the back surface material are laminated. Easy to prevent.

The thickness of the resin layer is preferably 0.03 to 2 mm, more preferably 0.1 to 0.8 mm, and particularly preferably 0.2 to 0.6 mm. When the thickness of the resin layer is 0.03 mm or more, the resin layer effectively buffers an impact caused by an external force from the transparent surface material side, and the display device can be protected. In particular, when the display device is sensitive to external force and easily affects display quality, the thickness is preferably 0.2 mm or more. Further, in the manufacturing method of the present embodiment, even if foreign matter exceeding the thickness of the resin layer is mixed between the transparent surface material and the display device, the thickness of the resin layer does not change greatly, and the light transmission performance is improved. There is little influence. If the thickness of the resin layer is 2 mm or less, bubbles are hardly left in the resin layer, and the entire thickness of the display device does not become unnecessarily thick. When the elastic modulus of the resin layer is small, the thickness is preferably 0.6 mm or less in order to suppress a shift in the bonding position of the display device over time.
As a method of adjusting the thickness of the resin layer, the thickness of a seal portion described later is adjusted, and the supply amount of the liquid photocurable resin composition for forming a resin layer supplied to the first face material is adjusted. The method of doing is mentioned.

[Seal part]
The seal portion is formed by applying and curing a liquid photocurable resin composition for forming a seal portion, which will be described later. Since the area outside the image display area of the display device is relatively narrow, the width of the seal portion is preferably narrowed. The width of the seal part is preferably 0.5 to 2 mm, and more preferably 0.8 to 1.6 mm.

[Shading printing section]
If necessary, a light-shielding printing part can be provided at the peripheral part of the transparent face material. The light-shielding printing unit hides the wiring member and the like connected to the display device so that areas other than the image display area of the display device cannot be viewed from the transparent surface material side. The light-shielding printing part can be provided on the joint surface with the resin layer of the transparent surface material or on the back surface thereof. It is preferable to install on the surface. When the transparent surface material is a glass plate, it is preferable to use ceramic printing containing a black pigment in the light-shielding printing portion because of high light shielding properties. The light-shielding printing part can also be formed by bonding a transparent film having the light-shielding printing part on the front or back surface to a transparent surface material. You may use the transparent surface material without a light-shielding printing part.

[shape]
The shape of the display device is usually rectangular.
The size of the display device is not particularly limited. However, since the manufacturing method of the present embodiment is particularly suitable for manufacturing a display device having a relatively large area, in the case of a PC monitor using a liquid crystal display device, the size is 0.3 m. In the case of × 0.18 m and a television receiver, 0.4 m × 0.3 m or more is appropriate, and 0.7 m × 0.4 m or more is particularly preferable. The upper limit of the size of the display device is often determined by the size of the display device. Also, a display device that is too large is likely to be difficult to handle during installation. The upper limit of the size of the display device is usually about 2.5 m × 1.5 m due to these restrictions. In the case of a small display, 0.14 m × 0.08 m or more is preferable.
Although the dimensions of the transparent surface material serving as the protective plate and the display device may be substantially equal, the transparent surface material is often slightly larger than the display device because of the relationship with other housings that house the display device. Conversely, depending on the structure of the other casing, the transparent surface material may be slightly smaller than the display device.

<Manufacturing method of display device>
The manufacturing method of the display device of this embodiment is a method having the following steps (a) to (d).
(A) A liquid photocuring property for forming a seal part containing a curable compound (I) and a photopolymerization initiator (C1) at the peripheral part of the surface of the first face material (back surface material (or surface material)). A step of applying the resin composition to form an uncured seal portion (however, when the first face material is a display device, the seal portion is formed on the surface on the image display side).
(B) The process of supplying the liquid photocurable resin composition for resin layer formation containing curable compound (II) and a photoinitiator (C2) to the area | region enclosed by the uncured seal part.
(C) In a reduced-pressure atmosphere of 100 Pa or less, a second face material (surface material (or back material)) is stacked on the photocurable resin composition for resin layer formation, and the first face material, Step of obtaining a laminated precursor in which the photocurable resin composition for resin layer formation is sealed with the face material of 2 and the uncured seal portion (however, an antireflection film is provided on the surface of the second face material) When the second face material is a display device, the side on which the image is displayed is the resin layer forming surface, and the back surface is in contact with the photocurable resin composition for resin layer formation. Layered so as to be in contact with the photocurable resin composition.

(D) A step of irradiating and curing the uncured seal portion and the photocurable resin composition for forming a resin layer with the laminated precursor placed in a pressure atmosphere of 50 kPa or more.
When the light shielding part is not formed on the transparent surface material, light is irradiated from the transparent surface material side of the laminated precursor to the seal part and the resin layer forming photocurable resin composition through the light transmitting part.
When the light shielding part is formed at the peripheral edge of the transparent surface material, the area of the light transmitting part surrounded by the light shielding part is made smaller than the area of the resin layer surrounded by the seal part, and the resin layer The photopolymerization initiator (C2) contained in the photocurable resin composition for forming is more than the absorption wavelength region (λ1) of the photopolymerization initiator (C1) contained in the photocurable resin composition for forming a seal part. The light having the absorption wavelength region (λ2) existing on the long wavelength side, and the light irradiated from the side of the laminated precursor in the step (d) is light having the wavelength within the absorption wavelength region (λ1) and the absorption wavelength. The light of the wavelength within the region (λ2) is included.

  The manufacturing method of this embodiment encloses the liquid photocurable resin composition for forming a resin layer between the first face material and the second face material in a reduced pressure atmosphere, and a high pressure such as in an atmospheric pressure atmosphere. In this method, a resin layer is formed by curing a photocurable resin composition for resin layer formation contained in an atmosphere. Containing the photocurable resin composition for resin layer formation under reduced pressure is not a method of injecting the photocurable resin for resin layer formation into a narrow and wide space between the first face material and the second face material. The photocurable resin composition for forming a resin layer is supplied to almost the entire surface of the first face material, and then the second face material is overlapped to form a resin between the first face material and the second face material. It is a method of enclosing the photocurable resin composition for layer formation.

  An example of a method for producing a transparent laminate by containment of a liquid resin layer forming photocurable resin composition under reduced pressure and curing of the resin layer forming photocurable resin composition under atmospheric pressure is known. For example, in WO 2008/81838 pamphlet and WO 2009/16943 pamphlet, a method for producing a transparent laminate and a photocurable resin composition used in the production method are described. Be incorporated.

[Step (a)]
First, an uncured seal portion is formed along the peripheral portion of one surface of the first face member. Whether the back material or the front material is used as the first face material is arbitrary.
When the first face material is a transparent face material that serves as a protective plate of the display device, the surface that forms the uncured seal portion is any one of the two surfaces. If the properties of the two surfaces are different, one of the necessary surfaces is selected. For example, when a surface treatment for improving the interfacial adhesive force with the resin layer is performed on one surface, an uncured seal portion is formed on the surface. Further, when an antireflection layer is provided on one surface, an uncured seal portion is formed on the back surface.
When the first face material is a display device, the surface that forms the uncured seal portion is the surface on the image display side.

The uncured seal portion is a liquid resin layer from the interface between the uncured seal portion and the first face material and the interface between the uncured seal portion and the second face material in step (c) described later It is important to have an interface adhesive strength that is higher than the level at which the photocurable resin composition for formation does not leak out, and a hardness that can maintain the shape. Therefore, the uncured seal part is preferably formed by applying a high viscosity photocurable resin composition for forming a seal part by printing, dispensing, or the like.
Moreover, in order to maintain the space | interval of a 1st face material and a 2nd face material, you may mix | blend the spacer particle | grains of a predetermined particle diameter with the photocurable resin composition for seal part formation.
Immediately after applying the photocurable resin composition for forming a seal part, the seal part is partially semi-cured by irradiating light for curing the seal part, thereby maintaining the shape of the seal part for a longer time. You can also.

[Photocurable resin composition for forming seal part]
The photocurable resin composition for forming a seal part (hereinafter sometimes referred to as a sealing material) is a liquid composition containing a photocurable curable compound (I) and a photopolymerization initiator (C1).
The viscosity of the photocurable resin composition for forming a seal part is preferably 500 to 3000 Pa · s, more preferably 800 to 2500 Pa · s, and still more preferably 1000 to 2000 Pa · s. When the viscosity is 500 Pa · s or more, the shape of the uncured seal portion can be maintained for a relatively long time, and the height of the seal portion can be sufficiently maintained. When the viscosity is 3000 Pa · s or less, the seal portion can be formed by a coating method.
The viscosity of the photocurable resin composition for forming a seal part is measured at 25 ° C. using an E-type viscometer.

(Curable compound (I))
The curable compound (I) is an oligomer having a curable group and having a number average molecular weight of 30,000 to 100,000 (A) from the viewpoint that the viscosity of the photocurable resin composition for forming a seal part is easily adjusted to the above range. And at least one monomer (B) having a curable group and a molecular weight of 125 to 600.

Examples of the curable group of the oligomer (A) or monomer (B) include addition polymerizable unsaturated groups (acryloyloxy group, methacryloyloxy group, etc.), combinations of unsaturated groups and thiol groups, and the curing rate. Are selected from the group consisting of an acryloyloxy group and a methacryloyloxy group, from the viewpoints of a high speed and a highly transparent seal part.
The curable group in the oligomer (A) and the curable group in the monomer (B) may be the same as or different from each other. Since the curable group in the relatively high molecular weight oligomer (A) is likely to be less reactive than the curable group in the relatively low molecular weight monomer (B), the curing of the monomer (B) proceeds rapidly. In addition, the viscosity of the entire composition may increase and the curing reaction may become inhomogeneous. In order to reduce the difference in reactivity between the two curable groups and obtain a uniform seal portion, the curable group of the oligomer (A) is changed to a relatively reactive acryloyloxy group and the curable property of the monomer (B). More preferably, the group is a methacryloyloxy group having relatively low reactivity.

The number average molecular weight of the oligomer (A) is 30,000 to 100,000, preferably 40,000 to 80,000, and more preferably 50,000 to 65,000. When the number average molecular weight of the oligomer (A) is within this range, it is easy to adjust the viscosity of the photocurable resin composition for forming a seal portion within the above range.
The number average molecular weight of the oligomer (A) is a number average molecular weight in terms of polystyrene obtained by GPC measurement. In addition, in GPC measurement, when a peak of an unreacted low molecular weight component (monomer or the like) appears, the number average molecular weight is determined by excluding the peak.

  The molecular weight of the monomer (B) is 125 to 600, preferably 140 to 400, and more preferably 150 to 350. When the molecular weight of the monomer (B) is 125 or more, volatilization of the monomer (B) when the display device is produced by the below-described reduced pressure lamination method is suppressed. When the molecular weight of the monomer (B) is 600 or less, the solubility of the monomer (B) in the high molecular weight oligomer (A) can be improved, and the viscosity adjustment as a photocurable resin composition for forming a seal part is suitable. Can be done.

(Oligomer (A))
The oligomer (A) preferably has an average of 1.8 to 4 curable groups per molecule from the viewpoint of curability of the photocurable resin composition for forming a seal portion and mechanical properties of the seal portion.
Examples of the oligomer (A) include urethane oligomers having a urethane bond, poly (meth) acrylates of polyoxyalkylene polyols, poly (meth) acrylates of polyester polyols, and the like.
Urethane oligomers synthesized using polyols and polyisocyanates as raw materials are preferred from the viewpoint that the mechanical properties of the cured resin, adhesion to the face material, etc. can be widely adjusted by molecular design of the urethane chain, etc. An oligomer (A1) is more preferable. The polyol is more preferably a polyoxyalkylene polyol.

(Urethane oligomer (A1))
Since the urethane oligomer (A1) having a number average molecular weight in the range of 30,000 to 100,000 has a high viscosity, it is difficult to synthesize by a normal method, and even if synthesized, it is difficult to mix with the monomer (B).
Therefore, after synthesizing the urethane oligomer (A1) by a synthesis method using the monomer (B) (the following monomers (B1) and (B2)), the obtained product is used as it is as a photocurable resin composition for forming a seal part. It is preferable to use it as a product, or to dilute the obtained product with a monomer (B) (the following monomer (B1), monomer (B3), etc.) to use as a photocurable resin composition for forming a seal part.
Monomer (B1): Monomer (B) having a curable group and no group that reacts with an isocyanate group.
Monomer (B2): A monomer having a curable group and a group that reacts with an isocyanate group among the monomers (B).
Monomer (B3): Monomer (B) having a curable group and a hydroxyl group.

Method for synthesizing urethane oligomer (A1):
A method in which a polyol and polyisocyanate are reacted in the presence of the monomer (B1) as a diluent to obtain a prepolymer having an isocyanate group, and then the monomer (B2) is reacted with the isocyanate group of the prepolymer.
Examples of the polyol and polyisocyanate include known compounds, for example, polyol (i) and diisocyanate (ii) described as raw materials for the urethane oligomer (a) described in International Publication No. 2009/016943. , Incorporated herein.

Examples of the polyol (i) include polyoxyalkylene polyols such as polyoxyethylene glycol and polyoxypropylene diol, polyester polyols, and polycardinate polyols. Among these, polyoxyalkylene polyol is preferable, and polyoxypropylene polyol is particularly preferable. Moreover, it is more preferable to replace a part of the oxypropylene group of the polyoxypropylene polyol with an oxyethylene group, since the compatibility with other components of the photocurable resin composition for resin layer formation can be increased.
Here, a part of the oxypropylene group may be substituted with an oxyethylene group, which means that a part of the oxypropylene structure constituting the polyoxypropylene polyol molecule is a molecular structure in which the oxyethylene structure is replaced. means. The same meaning is given to similar descriptions thereafter. The oxyethylene structure may be present randomly or in blocks in the polyoxypropylene polyol molecule. The oxyethylene structure may be inside the polyoxypropylene polyol molecule or immediately before the terminal hydroxyl group. When the oxyethylene structure is immediately before the terminal hydroxyl group, it can be obtained by adding ethylene oxide to the polyoxypropylene polyol.
The diisocyanate (ii) is preferably a diisocyanate selected from aliphatic diisocyanates, alicyclic diisocyanates and non-yellowing aromatic diisocyanates. Among them, examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate and the like. Examples of the alicyclic polyisocyanate include isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate) and the like. Examples of the non-yellowing aromatic diisocyanate include xylylene diisocyanate. These may be used alone or in combination of two or more.

  As the monomer (B1), an alkyl (meth) acrylate having an alkyl group having 8 to 22 carbon atoms (n-dodecyl (meth) acrylate, n-octadecyl (meth) acrylate, n-behenyl (meth) acrylate, etc.)), fat Examples include (meth) acrylates having a cyclic hydrocarbon group (such as isobornyl (meth) acrylate and adamantyl (meth) acrylate).

  Examples of the monomer (B2) include monomers having an active hydrogen (hydroxyl group, amino group, etc.) and a curable group. Specifically, a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 2 to 6 carbon atoms. (2-hydroxymethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc.) and the like, and hydroxy having 2 to 4 carbon atoms. A hydroxyalkyl acrylate having an alkyl group is preferred.

(Monomer (B))
The monomer (B) preferably has 1 to 3 curable groups per molecule from the viewpoint of curability of the photocurable resin composition for forming a seal portion and mechanical properties of the seal portion.
The photocurable resin composition for forming a seal part may contain a monomer (B1) used as a diluent in the method for synthesizing the urethane oligomer (A1) described above as the monomer (B). Moreover, the unreacted monomer (B2) used for the synthesis | combining method of the urethane oligomer (A1) mentioned above may be included as a monomer (B).

The monomer (B) preferably contains a monomer (B3) having a hydroxyl group from the viewpoint of the adhesion between the face material and the seal portion and the solubility of various additives described later.
As the monomer (B3) having a hydroxyl group, a hydroxy methacrylate having a hydroxyalkyl group having 1 to 2 hydroxyl groups and 3 to 8 carbon atoms (2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, 6 -Hydroxyhexyl methacrylate, glycerol monomethacrylate, etc.) are preferred, and 2-hydroxybutyl methacrylate is particularly preferred.

The content ratio of the monomer (B) in the photocurable resin composition for forming a seal part is the total (100% by mass) of the curable compound (I), that is, the total of the oligomer (A) and the monomer (B) (100% by mass). %) Is preferably 15 to 50% by mass, more preferably 20 to 45% by mass, and still more preferably 25 to 40% by mass. When the proportion of the monomer (B) is 15% by mass or more, the curability of the photocurable resin composition for forming a seal part and the adhesion between the face material and the seal part are good. It is easy to adjust the viscosity of the photocurable resin composition for forming a seal part to 500 Pa · s or more when the proportion of the monomer (B) is 50% by mass or less.
In addition, in the synthesis | combination of a urethane oligomer (A1), since the monomer (B2) which reacted with the isocyanate group of a prepolymer exists as a part of oligomer (A), the monomer (in the photocurable resin composition for seal part formation) It is not included in the content of B). On the other hand, in the synthesis of the urethane oligomer (A1), the monomer (B1) used as a diluent and the monomer (B) added after synthesizing the urethane oligomer (A1) are used in the photocurable resin composition for forming a seal part. It is included in the content of the monomer (B).

(Photopolymerization initiator (C1))
Examples of the photopolymerization initiator (C1) contained in the photocurable resin composition for forming a seal part include acetophenone, ketal, benzoin or benzoin ether, phosphine oxide, benzophenone, thioxanthone, and quinone. Examples of the photopolymerization initiator include acetophenone, ketal, and benzoin ether photopolymerization initiators. When curing with visible light having a short wavelength, a phosphine oxide-based photopolymerization initiator is more preferable from the viewpoint of the absorption wavelength region. By using two or more kinds of photopolymerization initiators (C1) having different absorption wavelength ranges in combination, the curing time can be further increased and the surface curability at the seal portion can be increased. In addition, when the light shielding printing part is provided on the transparent face material and the uncured seal part and the photocurable resin composition for resin layer formation that are sandwiched between the light shielding printing parts by light irradiation from the side surface of the face material are cured. May be used in combination with a photopolymerization initiator (C2) to be described later within a range that does not hinder the curing of the resin layer forming photocurable resin composition adjacent to the uncured seal portion. When used together, the content ratio of the polymerization initiator (C1) and the polymerization initiator (C2) is 50: 1 to (C1) :( C2) in terms of mass ratio from the viewpoint that curing can be efficiently and effectively performed. 5: 1 is preferred. In order to cure the photo-curable resin composition for forming a resin layer sandwiched between light-shielding printing parts in a short time with light irradiated from the side surface of the face material through an uncured seal material, light for forming a seal part is used. It is preferable that the curable resin composition does not contain a photopolymerization initiator (C2).

  The content of the photopolymerization initiator (C1) in the photocurable resin composition for forming a seal portion (when the photopolymerization initiator (C2) is included, the total amount of (C1) and (C2)) is a curable compound. 0.01-10 mass parts is preferable with respect to the whole (I), ie, a total of 100 mass parts of oligomer (A) and monomer (B), and 0.1-5 mass parts is more preferable.

(Additive)
A photocurable resin composition for forming a seal part can be prepared by using a polymerization inhibitor, a photocuring accelerator, a chain transfer agent, a light stabilizer (such as an ultraviolet absorber or a radical scavenger), an antioxidant, and a flame retardant as necessary. Various additives such as an agent, an adhesion improver (such as a silane coupling agent), a pigment, and a dye may be included, and a polymerization inhibitor and a light stabilizer are preferably included. In particular, by including a polymerization inhibitor in a smaller amount than the polymerization initiator, the stability of the photocurable resin composition for forming a seal portion can be improved, and the molecular weight of the cured resin layer can also be adjusted. When curing the sealing material with light irradiated from the side of the face material, use polymerization inhibitors, chain transfer agents, light stabilizers, pigments, dyes, etc. as much as possible, which has the effect of delaying the curing reaction, or It is preferable to reduce the content.

Examples of the polymerization inhibitor include polymerization inhibitors such as hydroquinone (2,5-di-t-butylhydroquinone, etc.), catechol (pt-butylcatechol, etc.), anthraquinone, phenothiazine, and hydroxytoluene. Can be mentioned.
Examples of the light stabilizer include ultraviolet absorbers (benzotriazole series, benzophenone series, salicylate series, etc.), radical scavengers (hindered amine series), and the like.
Examples of the antioxidant include phosphorus-based and sulfur-based compounds.
The total amount of these additives is preferably 10 parts by mass or less and preferably 5 parts by mass or less with respect to the total of the curable compound (I), that is, 100 parts by mass in total of the oligomer (A) and the monomer (B). More preferred.

[Step (b)]
After the step (a), a liquid photocurable resin composition for forming a resin layer is supplied to a region surrounded by an uncured seal portion.
The supply amount of the photocurable resin composition for resin layer formation is such that the space formed by the seal portion, the first face material, and the second face material is filled with the photocurable resin composition for resin layer formation, and The amount is set in advance so as to have a predetermined distance between the first face material and the second face material (that is, the resin layer has a predetermined thickness). At this time, it is preferable to consider in advance volume reduction due to curing shrinkage of the photocurable resin composition for resin layer formation. Therefore, the amount is preferably such that the thickness of the photocurable resin composition for resin layer formation is slightly larger than the predetermined thickness of the resin layer. When the curing shrinkage is small, the predetermined thickness of the resin layer and the thickness of the photocurable resin composition for resin layer formation may be substantially equal.
Examples of the supply method include a method in which the first face material is placed flat and supplied in a dot shape, a linear shape, or a planar shape by a supply means such as a dispenser or a die coater.

[Photocurable resin composition for resin layer formation]
The photocurable resin composition for resin layer formation has a storage shear modulus of 5 × 10 ² to 1 × 10 ⁵ Pa in dynamic viscoelasticity measurement after curing, and a loss tangent (tan δ) of 1.4 or less. It is the liquid photocurable resin composition which is.
The storage shear modulus and loss tangent are measured by applying dynamic shear strain to an uncured photocurable resin composition for resin layer formation using a dynamic viscoelasticity measuring device as described in detail later. While irradiating with light, the resin composition is cured.
When the shear modulus after curing is 5 × 10 ⁵ Pa or less, the stress generated by the shrinkage of the resin during curing can be sufficiently reduced, and the influence on the display quality of the display panel can be suppressed. When the shear modulus is 5 × 10 ² Pa or more, the resin layer is unlikely to be elastically deformed, and the positional deviation between the display device and the transparent surface material can be easily prevented. Further, when the loss tangent is 1.4 or less, the display device is sufficiently fixed to the transparent surface material even when the display device is installed vertically, and the resin layer is plastically deformed by the weight of the display device. Thus, it is possible to satisfactorily prevent the position of the display device from shifting with time.
The storage shear modulus is preferably 8 × 10 ^{2 to} 5 × 10 ⁴ Pa, more preferably 1 × 10 ^{3 to} 3 × 10 ⁴ Pa. The loss tangent is preferably 1.0 or less, more preferably 0.5 or less.

When using a display device that is susceptible to display performance due to stress caused by shrinkage during curing of the resin layer, such as an IPS type liquid crystal display device described later, the storage shear modulus after curing is 5 × 10 ² to It is preferable to use a liquid photocurable resin composition having 5 × 10 ³ Pa and a loss tangent (tan δ) smaller than 0.2. By making the shear modulus 5 × 10 ³ Pa or less, the stress generated by the shrinkage of the resin at the time of curing can be suppressed sufficiently small, and the loss tangent (tan δ) is low by making it smaller than 0.2. Even a resin layer having a shear modulus can suppress plastic deformation of the resin layer over time due to the weight of the display device. In this case, the loss tangent (tan δ) is more preferably 0.1 or less.
The lower limit value of the loss tangent is not particularly limited, and can be within a range that can be taken in production. However, in the case of a relatively flexible resin layer, it is usually 0.01 or more.

0.05-50 Pa.s is preferable and, as for the viscosity of the photocurable resin composition for resin layer formation, 1-20 Pa.s is more preferable. When the viscosity is 0.05 Pa · s or more, the proportion of the monomer (B ′) described later can be suppressed, and a decrease in physical properties of the resin layer can be suppressed. Moreover, since the component having a low boiling point is reduced, it is suitable for the reduced pressure lamination method described later. If the viscosity is 50 Pa · s or less, bubbles hardly remain in the resin layer.
The viscosity of the photocurable resin composition for resin layer formation is measured at 25 ° C. using an E-type viscometer.

The photocurable resin composition for forming a resin layer is preferably a liquid composition containing a photocurable curable compound (II), a photopolymerization initiator (C2), and a non-curable oligomer (D). The non-curable oligomer (D) has 0.8 to 3 hydroxyl groups per molecule which does not undergo a curing reaction with the curable compound (II) in the composition when the photocurable resin composition for resin layer formation is cured. It is an oligomer.
By containing the non-curable oligomer (D) in the photocurable resin composition for resin layer formation, it is possible to reduce the storage shear modulus while suppressing an increase in loss tangent (tan δ) of the cured resin layer. Therefore, the preferred ranges of the storage shear modulus and loss tangent (tan δ) in the dynamic viscoelasticity measurement can be achieved simultaneously.
Further, by containing a small amount of a chain transfer agent, the storage elastic modulus of the resin layer can be reduced by adjusting the molecular weight of the cured resin layer, but the curing rate is often slowed.
In the photocurable resin composition for forming a resin layer containing a relatively large amount of the non-curable oligomer (D) of the present invention, the elastic modulus can be adjusted by the content of the oligomer (D). It is preferable to reduce the content or not to include it. Specifically, the addition amount of the chain transfer agent is preferably 1 part by mass or less with respect to the total of the curable compound (II), that is, 100 parts by mass in total of the oligomer (A ′) and the monomer (B ′). Less than 0.5 parts by mass is more preferable. Examples of the chain transfer agent include n-dodecyl mercaptan.

(Curable compound (II))
The curable compound (II) in the photocurable resin composition for resin layer formation comprises at least one curable compound that undergoes a curing reaction when the photocurable resin composition for resin layer formation is cured. It is preferable that at least 1 type of a compound is the compound (IIa) which has a hydroxyl group which does not react at the time of hardening of the said photocurable resin composition for resin layer formation.
When the curable compound (II) contains the compound (IIa), a hydroxyl group is present in the cured product obtained by curing the curable compound (II) alone. The presence of such a hydroxyl group contributes to the stabilization of the non-curable oligomer in the photocurable resin composition for forming a resin layer.
Therefore, the compound (IIa) having a hydroxyl group that does not react at the time of curing may be any compound as long as an unreacted hydroxyl group exists after the curing reaction. What is necessary is just to leave a part in an unreacted state without carrying out hardening reaction.
The compound (IIa) having a hydroxyl group that does not react at the time of curing has a curable group contributing to the curing reaction and has a hydroxyl group, and may be a monomer or an oligomer having a repeating unit. Also good. In terms of facilitating adjustment of the viscosity of the uncured photocurable composition, a monomer having a curable group and a hydroxyl group is preferably used as the compound (IIa). Specific examples of the compound (IIa) which is a monomer having a hydroxyl group include hydroxy (meth) acrylate (2-hydroxypropyl (meth) acrylate, 2-hydroxyl having 1 to 2 hydroxyl groups and 3 to 8 carbon atoms). Hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, glycerol mono (meth) acrylate, etc.) are preferable, and 2-hydroxybutyl methacrylate is particularly preferable.

As the curable compound (II), one or more oligomers (A ′) having a curable group and having a number average molecular weight of 1,000 to 100,000, and a curable compound, from the viewpoint of easily adjusting the viscosity to the above range. It is preferable to include one or more monomers (B ′) having a group and a molecular weight of 125 to 600.
In this case, it is preferable to use a monomer (B3) having a curable group and a hydroxyl group and a molecular weight of 125 to 600 as at least a part of the monomer (B ′).

Examples of the curable group of the oligomer (A ′) or the monomer (B ′) include addition polymerizable unsaturated groups (acryloyloxy group, methacryloyloxy group, etc.), combinations of unsaturated groups and thiol groups, and the like. A group selected from the group consisting of an acryloyloxy group and a methacryloyloxy group is preferred from the viewpoint of a high curing rate and a highly transparent resin layer.
The curable group in the oligomer (A ′) and the curable group in the monomer (B ′) may be the same as or different from each other. Since the curable group in the relatively high molecular weight oligomer (A ′) tends to be less reactive than the curable group in the relatively low molecular weight monomer (B ′), the monomer (B ′) is cured first. There is a risk that the viscosity of the entire composition increases suddenly and the curing reaction becomes non-homogeneous. In order to reduce the difference in reactivity between the two curable groups and obtain a homogeneous resin layer, the curable group of the oligomer (A ′) is changed to a relatively highly reactive acryloyloxy group, and the monomer (B ′) More preferably, the curable group is a methacryloyloxy group having relatively low reactivity.

(Oligomer (A '))
The number average molecular weight of the oligomer (A ′) is preferably 1000 to 100,000, more preferably 10,000 to 70,000. When the number average molecular weight of the oligomer (A ′) is in this range, the viscosity of the photocurable resin composition for forming a resin layer can be easily adjusted to the above range.
The number average molecular weight of the oligomer (A ′) is a polystyrene-equivalent number average molecular weight obtained by GPC measurement. In addition, in GPC measurement, when a peak of an unreacted low molecular weight component (monomer or the like) appears, the number average molecular weight is determined by excluding the peak.

As the oligomer (A ′), those having an average of 1.8 to 4 curable groups per molecule are preferable from the viewpoints of the curability of the photocurable resin composition for resin layer formation and the mechanical properties of the resin layer. .
Examples of the oligomer (A ′) include urethane oligomers having urethane bonds, poly (meth) acrylates of polyoxyalkylene polyols, poly (meth) acrylates of polyester polyols, etc., and resins after curing by molecular design of urethane chains The urethane oligomer (A2) is preferable from the viewpoint that the mechanical properties, adhesion to the face material, and the like can be widely adjusted.
The urethane oligomer (A2) is synthesized by a method in which a polyol and polyisocyanate are reacted to obtain a prepolymer having an isocyanate group, and then the monomer (B2) is reacted with the isocyanate group of the prepolymer. preferable.
Examples of the polyol and polyisocyanate include known compounds, for example, polyol (i) and diisocyanate (ii) described as raw materials for the urethane oligomer (a) described in International Publication No. 2009/016943. , Incorporated herein.
As the urethane oligomer (A2), a commercially available product may be used, for example, EB230 (manufactured by Daicel-Cytec Corp., functional group number 2, recognized as a reaction product of polypropylene glycol / IPDI / 2-hydroxyethyl acrylate), U-200AX (manufactured by Shin-Nakamura Chemical Co., Ltd., functional group number 2, recognized as a reaction product of aliphatic polyester polyol / aliphatic or alicyclic polyisocyanate / 2-hydroxyethyl acrylate).

  The content ratio of the oligomer (A ′) is 20 to 90 in the total (100% by mass) of the curable compound (II), that is, the total (100% by mass) of the oligomer (A ′) and the monomer (B ′). % By mass is preferable, and 30 to 80% by mass is more preferable. When the proportion of the oligomer (A ′) is 20% by mass or more, the heat resistance of the resin layer becomes good. When the proportion of the oligomer (A ′) is 90% by mass or less, the curability of the photocurable resin composition for resin layer formation and the adhesion between the face material and the resin layer are improved. Since the oligomer (A ′) has a large molecular weight per curable group, in order to particularly suppress shrinkage during curing, the proportion of the oligomer (A ′) is more preferably 70 to 90% by mass. preferable.

(Monomer (B ′))
The molecular weight of the monomer (B ′) is preferably 125 to 600, and more preferably 140 to 400. When the molecular weight of the monomer (B ′) is 125 or more, the volatilization of the monomer when the display device is produced by the below-described reduced pressure lamination method is suppressed. When the molecular weight of the monomer (B ′) is 600 or less, the adhesion between the face material and the resin layer becomes good.
The monomer (B ′) preferably has 1 to 3 curable groups per molecule from the viewpoint of the curability of the photocurable resin composition for forming a resin layer and the mechanical properties of the resin layer.
The content ratio of the monomer (B ′) is 10 to 80 of the entire curable compound (II) (100 mass%), that is, the total (100 mass%) of the oligomer (A ′) and the monomer (B ′). % By mass is preferable, and 20 to 70% by mass is more preferable.

The monomer (B ′) preferably contains a monomer (B3) having a curable group and a hydroxyl group. The monomer (B3) contributes to the stabilization of the non-curable oligomer (D). Further, when the monomer (B3) is contained, good adhesion between the face material and the resin layer is easily obtained. The number of hydroxyl groups in one molecule of the monomer (B3) can be arbitrarily selected as long as the non-curable oligomer (D) can be stabilized, but 1 to 2 in one molecule from the viewpoint of availability. It is preferable that
As a monomer (B3) which has a hydroxyl group, the thing similar to the monomer (B3) in the photocurable resin composition for seal | sticker part formation is mentioned, 2-hydroxybutyl methacrylate is especially preferable.
The content ratio of the monomer (B3) is 10 to 60 mass in the total (100 mass%) of the curable compound (II), that is, the total (100 mass%) of the oligomer (A ′) and the monomer (B ′). % Is preferable, and 20-50 mass% is more preferable. When the content ratio of the monomer (B3) is 10% by mass or more, the effects of improving the stability of the photocurable resin composition for resin layer formation and improving the adhesion between the face material and the resin layer are sufficiently obtained. Cheap. It is preferable for the content ratio of the monomer (B3) to be 60% by mass or less since the hardness of the cured product made of the photocurable resin composition for resin layer formation does not become too high.

The monomer (B ′) preferably contains the following monomer (B4) from the viewpoint of the mechanical properties of the resin layer. Since the monomer (B4) decreases the glass transition temperature (Tg) of the cured resin layer, the monomer (B4) contributes to a decrease in the elastic modulus of the cured resin layer and improves the flexibility of the resin layer.
However, it may be preferable to reduce the content of the monomer (B4) or not to include it, for example, when the curability of the photocurable resin composition for forming a resin layer is increased to shorten the time required for curing.
Monomer (B4): one or more selected from the group consisting of alkyl methacrylate having an alkyl group having 8 to 22 carbon atoms. When the number of carbon atoms is 8 or more, the glass transition temperature of the cured product can be lowered, and when the number of carbon atoms is 22 or less, the starting alcohol can be easily obtained via natural products. Is preferable.
Examples of the monomer (B4) include n-dodecyl methacrylate, n-octadecyl methacrylate, n-behenyl methacrylate and the like, and n-dodecyl methacrylate or n-octadecyl methacrylate is preferable.
The content ratio of the monomer (B4) is 5 to 50 mass in the total (100 mass%) of the curable compound (II), that is, the total (100 mass%) of the oligomer (A ′) and the monomer (B ′). % Is preferable, and 15 to 40% by mass is more preferable. When the content ratio of the monomer (B4) is 5% by mass or more, a sufficient addition effect of the monomer (B4) is easily obtained.

(Photopolymerization initiator (C2))
Examples of the photopolymerization initiator (C2) contained in the photocurable resin composition for resin layer formation include acetophenone, ketal, benzoin or benzoin ether, phosphine oxide, benzophenone, thioxanthone, and quinone. Photopolymerization initiators may be mentioned, and phosphine oxide and thioxanthone photopolymerization initiators are preferable, and phosphine oxide is particularly preferable in terms of suppressing coloring after the photopolymerization reaction.
The content of the photopolymerization initiator (C2) in the photocurable resin composition for resin layer formation is 100 parts by mass in total of the curable compound (II), that is, the oligomer (A ′) and the monomer (B ′). Is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass.

  When a part of the photocurable resin composition for resin layer formation adjacent to the sealing material is cured by light irradiated from the side of the face material, the photopolymerization initiator (C2) is the photopolymerization initiator. Those having an absorption wavelength region (λ2) existing on the longer wavelength side than the absorption wavelength region (λ1) of (C1) are preferable. The photopolymerization initiator (C2) may have only an absorption wavelength region (λ2), and has an absorption wavelength region (λ1 ′) and an absorption wavelength region (λ2) overlapping with the absorption wavelength region (λ1). It may be a thing.

(Non-curable oligomer (D))
Since the non-curable oligomer (D) is well compatible in the photo-curable resin composition for forming a resin layer and does not contribute to curing, the shrinkage during curing of the resin layer without impairing transparency and homogeneity. The stress due to can be reduced.
The non-curable oligomer (D) has 0.8 to 3 hydroxyl groups per molecule which does not undergo a curing reaction with the curable compound (II) in the composition when the photocurable resin composition for resin layer formation is cured. It is an oligomer. The number of hydroxyl groups per molecule is more preferably 2 to 3. When the number of hydroxyl groups per molecule is 0.8 or more, non-curing property is caused by the interaction between hydroxyl groups between non-curable oligomers or between a non-curable oligomer and a cured product obtained from the curable compound (II). It is preferable in that the oligomer can be stably held. If the number of hydroxyl groups per molecule is 3 or less, the non-curable oligomer can be satisfactorily compatible in the photocurable resin composition for resin layer formation. preferable.
The number average molecular weight (Mn) per hydroxyl group of the non-curable oligomer (D) is preferably 400 to 8000. When the number average molecular weight per hydroxyl group is 400 or more, the polarity of the non-curable oligomer (D) does not become too high, and good with the curable compound (II) in the photocurable resin composition for resin layer formation It is easy to obtain good compatibility. When the number average molecular weight per hydroxyl group is 8000 or less, in the resin layer after curing due to the interaction between the hydroxyl group derived from the curable compound (II) and the hydroxyl group of the non-curable oligomer (D). Thus, the effect of stabilizing the non-curable oligomer (D) is easily obtained. It is speculated that hydrogen bonds are involved in this interaction.
A non-curable oligomer (D) may be used individually by 1 type, and may use 2 or more types together.

Examples of the non-curable oligomer (D) containing a hydroxyl group include a high molecular weight polyol, and a polyoxyalkylene polyol, a polyester polyol, and a polycarbonate polyol are preferable.
Examples of the polyoxyalkylene polyol include polyoxyalkylene monools, polyoxyalkylene diols, and polyoxyalkylene triols having a repeating unit of oxyalkylene having 2 to 4 carbon atoms. Specific examples include polyoxyethylene glycol, polyoxypropylene diol (hereinafter also referred to as polypropylene glycol), polyoxypropylene triol, and polyoxytetramethylene glycol.
The number average molecular weight (Mn) per hydroxyl group of the polyoxyalkylene polyol is preferably from 400 to 8000, more preferably from 600 to 5000.
As the polyester polyol, an aliphatic polyester having a residue of an aliphatic diol such as ethylene glycol, propylene glycol or 1,4-butanediol and a residue of an aliphatic dicarboxylic acid such as glutaric acid, adipic acid or sebacic acid Diols are mentioned.
Examples of the polycarbonate polyol include aliphatic polycarbonate diols having a diol residue such as 1,6-hexanediol, and aliphatic polycarbonate diols such as ring-opening polymers of aliphatic cyclic carbonates.
The number average molecular weight (Mn) per hydroxyl group of the polyester polyol or polycarbonate polyol is preferably 400 to 8000, more preferably 800 to 6000.
The number average molecular weight of the non-curable oligomer (D) in the present specification is the hydroxyl value A (KOH mg / g) measured in accordance with JISK1557-1 (2007 edition) and the non-curable oligomer (D) in one molecule. It is a value calculated by the following formula (1) from the number B of hydroxyl groups.
Molecular weight of non-curable oligomer (D) = 56.1 × B × 1000 / A (1)

A polyoxyalkylene polyol is preferably used as the non-curable oligomer (D) from the viewpoint that the elastic modulus of the resin layer after curing tends to be lower, and polyoxypropylene polyol is particularly preferable. Further, as described later, in order to adjust the polarity of the non-curable oligomer (D), a part of the oxypropylene group of the polyoxypropylene polyol may be substituted with an oxyethylene group. The fact that a part of the oxypropylene group may be substituted with an oxyethylene group is the same as that in the above-described polyol (i).
For example, in terms of compatibility, the oligomer (A ′) is a urethane oligomer synthesized using polyoxyalkylene polyol and polyisocyanate as raw materials, and the non-curable oligomer (D) is a polyoxyalkylene polyol. preferable.

In the present invention, in order to stabilize the photocurable resin composition for resin layer formation when uncured and to suppress separation of the non-curable oligomer (D) from the cured resin layer, the oligomer (A ′) and The non-curable oligomer (D) preferably has a molecular chain having the same structure or a similar structure.
Specifically, for example, a compound having a hydroxyl group such as a polyol (hereinafter sometimes referred to as a hydroxyl group-containing compound) as a raw material for synthesizing the oligomer (A ′) in the photocurable resin composition for forming a resin layer. It is preferable to use the same hydroxyl group-containing compound as the non-curable oligomer (D).
For example, when the oligomer (A ′) is a urethane oligomer synthesized using polyoxyalkylene polyol and polyisocyanate as raw materials, it is preferable to use the polyoxyalkylene polyol as the non-curable oligomer (D).

Alternatively, when the hydroxyl group-containing compound as the raw material of the oligomer (A ′) and the hydroxyl group-containing compound used as the non-curable oligomer (D) are not the same, both molecular chains have a common repeating unit, etc. It is preferable that they have a common structure and have the same polarity. Polarity adjustment methods include, for example, a method of increasing the polarity by introducing a polar group, a method of increasing the polarity by substituting a part of the oxypropylene group with an oxyethylene group, and reducing the molecular weight per hydroxyl group For example, a method for increasing the polarity. These methods may be combined.
For example, when the oligomer (A ′) is a urethane oligomer synthesized using polyoxypropylene polyol (a ′) in which a part of oxypropylene group is substituted with oxyethylene group and polyisocyanate as raw materials, It is preferable to use, as the non-curable oligomer (D), a polyoxypropylene polyol which does not have a polyoxypropylene polyol having a molecular weight per hydroxyl group smaller than that of the polyol (a ′).

As an example of the most preferable photocurable resin composition for forming a resin layer, a prepolymer having an isocyanate group by reacting a polyoxypropylene diol in which a part of the oxypropylene group is substituted with an oxyethylene group and a polyisocyanate compound is reacted. After being obtained, the urethane oligomer (A2) obtained by reacting with the monomer (B2) is included as an oligomer (A ′), and a part of the oxypropylene group is the same as the raw material of the urethane oligomer (A2). And a composition containing a monomer (B3) having a hydroxyl group as the monomer (B ′).
Thus, when the oligomer (A ′) partially has the same molecular structure as the non-curable oligomer (D), the compatibility of the non-curable oligomer (D) in the composition is further increased, and the monomer ( When B ′) has a hydroxyl group, the non-cured compound (II) is non-cured in the cured product due to the interaction between the hydroxyl group in the molecular structure after curing of the curable compound (II) and the hydroxyl group in the molecular structure of the non-curable oligomer (D). It is considered that the curable oligomer (D) can exist stably.

  As another example, after reacting a polyoxypropylene diol in which a part of the oxypropylene group is substituted with an oxyethylene group and a polyisocyanate compound to obtain a prepolymer having an isocyanate group, the monomer (B2) and A polyoxypropylene diol that contains the urethane oligomer (A2) obtained by the reaction as an oligomer (A ′) and is not substituted with an oxyethylene group, and has a molecular weight higher than that of the polyoxypropylene diol as a raw material of the urethane oligomer (A2) Even in the composition containing a monomer (B3) having a hydroxyl group as the monomer (B ′), a good phase of the non-curable oligomer (D) in the composition is contained as a non-curable oligomer (D). Solubility can be obtained, and non-curable oligomer (D) is stabilized in the cured product It can be present.

  As for content of the non-curable oligomer (D) in the photocurable resin composition for resin layer formation, 10-90 mass% is preferable. When the content of the non-curable oligomer is 10% by mass or more, an effect of reducing the stress generated by the shrinkage of the resin at the time of curing can be sufficiently obtained. When the amount is 90% by mass or less, the face materials are easily fixed to each other, and the positional deviation with time is easily prevented after the surface material and the back material are joined. The content of the non-curable oligomer (D) is preferably set so that preferable values of the storage shear modulus and loss tangent are obtained according to the composition of the curable compound (II). A more preferable range is 30 to 80% by mass.

(Additive)
The photocurable resin composition for resin layer formation can be prepared by using polymerization inhibitors, photocuring accelerators, chain transfer agents, light stabilizers (ultraviolet absorbers, radical scavengers, etc.), antioxidants, and flame retardants as necessary. Various additives such as an agent, an adhesion improver (such as a silane coupling agent), a pigment, and a dye may be included, and a polymerization inhibitor or a light stabilizer is preferably included. In particular, by including a polymerization inhibitor in a smaller amount than the polymerization initiator, the stability of the photocurable resin composition for resin layer formation can be improved, and the molecular weight of the cured resin layer can also be adjusted.

[Step (c)]
After the step (b), the first face material supplied with the photocurable resin composition for forming a resin layer is put into a decompression device, and the surface of the curable resin composition is placed on the fixed support disk in the decompression device. Lay the first face material flat so that it faces up.
A movement support mechanism that can move in the vertical direction is provided in an upper portion of the decompression device, and a second face material is attached to the movement support mechanism. When the second face material is a display device, the surface on which the image is displayed is directed downward. When the antireflection layer is provided on the surface of the second face material, the surface on which the antireflection layer is not formed is directed downward.
The second face material is placed above the first face material and at a position not in contact with the photocurable resin composition for resin layer formation. That is, the resin layer forming photocurable resin composition on the first face material and the second face material are opposed to each other without being brought into contact with each other.

A moving support mechanism that can move in the vertical direction may be provided in the lower part of the decompression device, and the first face material supplied with the curable resin composition may be placed on the moving support mechanism. In this case, the second face material is attached to a fixed support board provided at the upper part in the decompression device, and the first face material and the second face material are opposed to each other.
Moreover, you may support both the 1st face material and the 2nd face material with the movement support mechanism provided in the upper and lower sides in a decompression device.

After disposing the first face material and the second face material at predetermined positions, the inside of the pressure reducing device is depressurized to form a predetermined reduced pressure atmosphere. If possible, the first face material and the second face material may be positioned at predetermined positions in the decompression device during the decompression operation or after a predetermined decompressed atmosphere.
After the inside of the decompression device has a predetermined decompressed atmosphere, the second face material supported by the moving support mechanism is moved downward to form a photocurable resin composition for resin layer formation on the first face material. A second face material is overlaid on top.

By superimposing, the surface of the first face material (in the case of a display device, the image display side surface), the surface of the second face material (in the case of a display device, the image display side surface), The photocurable resin composition for resin layer formation is sealed in the space surrounded by the curing seal portion.
At the time of superposition, the photocurable resin composition for resin layer formation is spread by the weight of the second face material, the pressure from the moving support mechanism, etc., and the photocurable resin composition for resin layer formation in the space. When the product is filled and then exposed to a high pressure atmosphere in step (d), a layer of the photocurable resin composition for forming a resin layer with few or no bubbles is formed.

  The reduced pressure atmosphere at the time of superposition is 100 Pa or less, and preferably 10 Pa or more. If the reduced-pressure atmosphere is too low, each component (curable compound, photopolymerization initiator, polymerization inhibitor, light stabilizer, etc.) contained in the photocurable resin composition for resin layer formation may be adversely affected. . For example, if the reduced-pressure atmosphere is too low, each component may be vaporized, and it may take time to provide the reduced-pressure atmosphere. The pressure in the reduced pressure atmosphere is more preferably 15 to 40 Pa.

  The time from when the first face material and the second face material are overlapped to when the reduced-pressure atmosphere is released is not particularly limited, and immediately after the photocurable resin composition for resin layer formation is sealed, the reduced-pressure atmosphere. May be released, and after sealing the photocurable resin composition for resin layer formation, the reduced pressure state may be maintained for a predetermined time. By maintaining the depressurized state for a predetermined time, the photocurable resin composition for resin layer formation flows in the sealed space, the interval between the first face material and the second face material becomes uniform, and the atmospheric pressure is increased. However, it becomes easy to maintain a sealed state. The time for maintaining the reduced pressure state may be several hours or longer, but is preferably within 1 hour, more preferably within 10 minutes from the viewpoint of production efficiency.

  In the manufacturing method of the present embodiment, when a photocuring resin composition for forming a seal part having a high viscosity is applied to form an uncured seal part, the resin layer in the laminated precursor obtained in step (c) The thickness of the forming photocurable resin composition can be made relatively thick, such as 10 μm to 3 mm.

[Step (d)]
After releasing the reduced pressure atmosphere in the step (c), the lamination precursor is placed in a pressure atmosphere having an atmospheric pressure of 50 kPa or more.
When the layered precursor is placed in a pressure atmosphere of 50 kPa or more, bubbles are present in the sealed space in the layered precursor because it is pressed in the direction in which the first and second face materials are in close contact with each other due to the increased pressure. Then, the photocurable resin composition for resin layer formation flows into the bubbles, and the entire sealed space is uniformly filled with the photocurable resin composition for resin layer formation.
The pressure atmosphere is usually 80 kPa to 120 kPa. The pressure atmosphere may be an atmospheric pressure atmosphere or a higher pressure. An atmospheric pressure atmosphere is most preferred because operations such as curing of the photocurable resin composition for resin layer formation can be performed without requiring special equipment.

  The time from when the lamination precursor is placed in a pressure atmosphere of 50 kPa or more to the start of curing of the photocurable resin composition for resin layer formation (hereinafter referred to as high pressure holding time) is not particularly limited. In the case where the process from taking the laminated precursor out of the decompression device to the curing device and starting the curing is performed under an atmospheric pressure atmosphere, the time required for the process becomes the high pressure holding time. Therefore, when there is no bubble in the sealed space of the laminated precursor already when placed in an atmospheric pressure atmosphere, or when the bubble disappears during the process, the photocurable resin composition for resin layer formation is immediately The object can be cured. When it takes time for the bubbles to disappear, the lamination precursor is held in an atmosphere at a pressure of 50 kPa or more until the bubbles disappear. In addition, since there is usually no problem even if the high pressure holding time is increased, the high pressure holding time may be increased due to other necessity in the process. The high-pressure holding time may be a long time of one day or longer, but is preferably within 6 hours from the viewpoint of production efficiency, more preferably within 1 hour, and particularly within 10 minutes from the viewpoint of further increasing production efficiency. preferable.

Next, a resin layer for bonding the display device and the protective plate is formed by curing the photocurable resin composition for resin layer formation in a state where the lamination precursor is placed in a pressure atmosphere of 50 kPa or more, and display The device is manufactured.
The photocurable resin composition for forming a resin layer and the photocurable resin composition for forming a seal part are cured by irradiation with light. For example, the photocurable resin composition is cured by irradiating ultraviolet light or short-wavelength visible light from a light source (ultraviolet lamp, high-pressure mercury lamp, black light, chemical lamp, UV-LED, etc.).
At this time, the uncured seal portion formed from the photocurable resin composition for forming the seal portion may be cured simultaneously with the curing of the photocurable resin composition for forming the resin layer. You may make it harden | cure beforehand before hardening of the photocurable resin composition for use. Moreover, when the light shielding printing part is formed in a part of transparent surface material and it is pinched | interposed into the light shielding printing part and a seal part is formed, it is used for hardening of the photocurable resin composition for resin layer formation. Since it is difficult to cure the seal portion by light passing through the light transmitting portion of the transparent surface material, the seal portion may be cured after the photocurable resin composition for resin layer formation is cured.
For example, light is irradiated to the photocurable resin composition for resin layer formation from the light-transmitting side of the first surface material and the second surface material of the lamination precursor, and the lamination precursor side From the direction, light is irradiated to the light-curing resin composition for forming an uncured seal part and a resin layer sandwiched between the light-shielding part and the display device.

Of the first face material and the second face material, the display device does not have light transmittance when not operated, and therefore irradiates light from the side of the transparent face material serving as a protective plate through the light transmitting portion.
Further, a light-shielding printing part is provided in the peripheral part of the transparent surface material, and an uncured seal part and a photocurable resin composition for resin layer formation are present in a region sandwiched between the light-shielding printing part and the display device. The light from the transparent portion of the transparent face material cannot be cured sufficiently. Therefore, light is irradiated from the side of the display device.

The light is preferably ultraviolet light or visible light of 450 nm or less. In particular, when an antireflection layer is provided on the transparent surface material, and the transparent resin film on which the antireflection layer or the antireflection layer is formed or the adhesive layer provided between the antireflection film and the transparent surface material does not transmit ultraviolet rays. Requires curing with visible light.
As a light source for light irradiation from the side, a light source used for light irradiation from the side of the transparent surface material may be used. However, an LED that emits ultraviolet light or visible light of 450 nm or less may be used. This is preferable because it is suitable for efficient light irradiation at a specific location.
As the light irradiation step, light irradiation from the side after the light irradiation from the transparent surface material side may be performed, or vice versa, or the light irradiation may be performed simultaneously. In order to further accelerate the photocuring of the photocurable resin composition for forming the resin layer and the resin layer, it is preferable to irradiate light from the side first or from the side of the transparent surface material simultaneously with the side. . In addition, when the curing of the photocurable resin composition takes time, such as the curing of the photocurable resin composition for resin layer formation with time after light irradiation, the photocurable resin composition for resin layer formation After substantially completing the curing, the seal portion can be cured by light irradiation from the side.

〔Concrete example〕
In the manufacturing method of this embodiment, it is arbitrary whether a back surface material or a surface material is used as the first face material. Therefore, the display device can be manufactured by the following two types of methods, depending on the selection of the first face material.
(Α-1) A method in which a display device (back surface material) is used as the first surface material, and a transparent surface material (surface material) serving as a protective plate is used as the second surface material.
(Α-2) A method of using a transparent surface material (surface material) serving as a protective plate as the first surface material and using a display device (back surface material) as the second surface material.

  Hereinafter, the method for manufacturing the display device of FIG. 1 will be described in detail with reference to the drawings, taking the method (α-1) as an example.

(Process (a))
As shown in FIG. 3 and FIG. 4, the photocurable resin composition for forming a seal portion is applied along the peripheral portion of the display device 50 (first face material) by a dispenser (not shown) or the like to be uncured. The seal portion 12 is formed.
A wiring member such as an FPC that transmits an electrical signal for operating the display device may be installed on the outer periphery of the display device. When holding each face material in the manufacturing method of the present embodiment, it is preferable to dispose the display device as the first face material in terms of facilitating the arrangement of the wiring members.

(Process (b))
Next, as shown in FIGS. 5 and 6, the photocurable resin composition 14 for resin layer formation is supplied to the rectangular region 13 surrounded by the uncured seal portion 12 of the display device 50. The supply amount of the resin layer forming photocurable resin composition 14 is such that the space sealed by the uncured seal portion 12, the display device 50, and the transparent surface material 10 (see FIG. 7) is photocurable for resin layer formation. The amount is set in advance so as to be filled with the resin composition 14.

As shown in FIGS. 5 and 6, the resin layer forming photocurable resin composition 14 is supplied by placing the display device 50 flat on the lower surface plate 18 and moving the resin layer forming light by the dispenser 20 that moves in the horizontal direction. It is carried out by supplying the curable resin composition 14 in a linear shape, a strip shape or a dot shape.
The dispenser 20 is horizontally movable over the entire range of the region 13 by a known horizontal movement mechanism including a pair of feed screws 22 and a feed screw 24 orthogonal to the feed screws 22. A die coater may be used instead of the dispenser 20.

(Process (c))
Next, as shown in FIG. 7, the display device 50 and the transparent face material 10 (second face material) are carried into the decompression device 26. An upper surface plate 30 having a plurality of suction pads 32 is disposed in the upper portion of the decompression device 26, and a lower surface plate 31 is disposed in the lower portion. The upper surface plate 30 can be moved in the vertical direction by an air cylinder 34.
The transparent face material 10 is attached to the suction pad 32. The display device 50 is fixed on the lower surface plate 31 with the surface to which the photocurable resin composition 14 for resin layer formation is supplied facing up.

  Next, the air in the decompression device 26 is sucked by the vacuum pump 28. After the atmospheric pressure in the decompression device 26 reaches, for example, a reduced pressure atmosphere of 15 to 40 Pa, the display device 50 standing by below in a state where the transparent surface material 10 is sucked and held by the suction pad 32 of the upper surface plate 30. The air cylinder 34 is operated and moved downward. Then, the display device 50 and the transparent surface material 10 are overlapped with each other via the uncured seal portion 12 to form a lamination precursor, and the lamination precursor is held for a predetermined time in a reduced pressure atmosphere.

  The mounting position of the display device 50 with respect to the lower surface plate 31, the number of suction pads 32, the mounting position of the transparent surface material 10 with respect to the upper surface plate 30, and the like depend on the size, shape, etc. of the display device 50 and the transparent surface material 10. Adjust as appropriate. At this time, an electrostatic chuck is used as the suction pad, and the glass substrate is stabilized by adopting the electrostatic chuck holding method described in the specification (incorporated herein) attached to Japanese Patent Application No. 2008-206124. Can be maintained under a reduced pressure atmosphere.

(Process (d))
Next, after the inside of the decompression device 26 is set to atmospheric pressure, for example, the laminated precursor is taken out from the decompression device 26. When the lamination precursor is placed in an atmospheric pressure atmosphere, the surface of the lamination precursor on the display device 50 side and the surface on the transparent face material 10 side are pressed by atmospheric pressure, and the photocurable resin for forming a resin layer in the sealed space The composition 14 is pressed by the display device 50 and the transparent surface material 10. This pressure causes the resin layer forming photocurable resin composition 14 in the sealed space to flow, and the entire sealed space is uniformly filled with the resin layer forming photocurable resin composition 14.

Next, in the case where a light shielding printing part is provided on the transparent surface material and the uncured seal part and the photocurable resin composition for resin layer formation sandwiched between the light shielding printing parts are cured first, as shown in FIG. Further, light (ultraviolet light or visible light of 450 nm or less) is applied to the uncured seal portion 12 and the photocurable resin composition 14 for resin layer formation sandwiched between the light-shielding printing portion 55 and the display device 50 from the side of the laminated precursor. Is applied to the entire circumference of the display device, and light (ultraviolet light or visible light having a wavelength of 450 nm or less) is applied to the photocurable resin composition for resin layer formation 14 through the light-transmitting portion 56 from the transparent surface material 10 side. The display device 1 is manufactured by curing the uncured seal portion 12 and the photocurable resin composition 14 for resin layer formation inside the precursor.
When the transparent face material does not have a light-shielding print portion, the entire surface of the lamination precursor is irradiated with light from the transparent face material 10 side, and the uncured seal portion 12 and the resin layer forming photocurability inside the lamination precursor. The display device 1 is manufactured by curing the resin composition 14.

  The method for manufacturing the display device of the present embodiment has been specifically described above by taking the case of the method (α-1) as an example, but the display device can be manufactured in the same manner in the case of the other method (α-2). .

[Operation and Effect: Manufacturing Method of Display Device]
According to the display device manufacturing method of the present embodiment described above, a display device having a relatively large area can be manufactured without generating bubbles in the resin layer. Even if bubbles remain in the resin layer forming photocurable resin composition sealed under reduced pressure, the pressure is also applied to the resin layer forming photocurable resin composition sealed under a high pressure atmosphere before curing. , The volume of the bubbles decreases, and the bubbles disappear easily. For example, the volume of the gas in the bubbles in the photocurable resin composition for forming a resin layer sealed under 100 Pa is considered to be 1/1000 under 100 kPa. Since the gas may be dissolved in the photocurable resin composition for resin layer formation, the gas in the minute volume of bubbles quickly dissolves and disappears in the photocurable resin composition for resin layer formation.

  In addition, even if pressure such as atmospheric pressure is applied to the photocurable resin composition for resin layer formation after sealing, the liquid photocurable resin composition for resin layer formation is a fluid composition. The pressure is evenly distributed on the surface of the device, and no further stress is applied to the part of the surface of the display device that is in contact with the photocurable resin composition for resin layer formation. Few.

Moreover, the interface adhesive force of the resin layer by the hardening of the photocurable resin composition for resin layer formation, a display device, and a transparent surface material is higher than the interface adhesive force by heat sealing | fusion. In addition, since the photocurable resin composition for forming a fluid resin layer is pressurized to adhere to the surface of the display device or the transparent surface material and cured in that state, higher interfacial adhesion can be obtained, and the display device In addition, uniform adhesion to the surface of the transparent face material is obtained, and the interfacial adhesive force is unlikely to be partially reduced.
Therefore, there is a low possibility that peeling will occur on the surface of the resin layer, and there is little possibility that moisture or corrosive gas will enter from a portion where the interfacial adhesive force is insufficient.

  Also, compared to a method (injection method) in which a fluid photocurable resin composition for forming a resin layer is injected into a narrow and wide space between two face materials, there is less generation of bubbles and in a short time. The photocurable resin composition for resin layer formation can be filled. Moreover, there are few restrictions on the viscosity of the photocurable resin composition for forming a resin layer, and a high-viscosity photocurable resin composition for forming a resin layer can be easily filled. Therefore, a high-viscosity photocurable resin composition for forming a resin layer containing a relatively high molecular weight curable compound capable of increasing the strength of the resin layer can be used.

  Further, the photopolymerization initiator (C2) of the photocurable resin composition for resin layer formation is present on the longer wavelength side than the absorption wavelength region (λ1) of the photopolymerization initiator (C1) of the uncured seal portion. Using a photopolymerization initiator (C2) having an absorption wavelength range (λ2), and light irradiated from the side of the laminated precursor, light having a wavelength within the absorption wavelength range (λ1) and an absorption wavelength range (λ2 ) By using both light having wavelengths within the absorption wavelength region (λ2) that has not been absorbed by the photopolymerization initiator (C1) of the uncured seal portion. The photo-curing resin composition for resin layer formation is sufficiently cured by the photopolymerization initiator (C2) having an absorption wavelength region (λ2) that has sufficiently reached the sandwiched photo-curing resin composition for resin layer formation. Can be done.

[Function and effect: curable resin composition]
In joining the display device to the transparent surface material (protective plate), the stress on the display device is reduced by reducing the shrinkage rate when the curable resin is cured, or by reducing the elastic modulus of the cured resin layer. It is possible to effectively prevent the display quality such as display unevenness from being impaired. On the other hand, if the elastic modulus of the resin layer is too low, the display device and the transparent surface material may be displaced due to elastic deformation of the resin layer. Furthermore, according to the knowledge of the present inventors, even when the elastic modulus of the resin layer is sufficiently high, the resin layer is used when the weight of the display device is applied to the resin layer for a long time, such as when the display device is arranged vertically. The layer may be plastically deformed over time, and the accuracy of the bonding position of the display device may be reduced.
In contrast, the curable resin composition of the present invention has a storage shear modulus of 5 × 10 ² to 1 × 10 ⁵ Pa and a loss tangent of 1.4 or less in the dynamic viscoelasticity measurement after curing. As a result, it is possible to reduce the stress due to the curing shrinkage of the resin layer while preventing the displacement of the face materials (display device and protective plate) due to the elastic deformation of the resin layer, and to reduce the stress due to the plastic deformation of the resin layer over time. Misalignment between the display devices and the protective plate can be effectively prevented.

In particular, when the display device is a liquid crystal display device and is an IPS (In-plane Switching) type or a TN (Twisted Nematic) type liquid crystal display device in which an optical film for improving the viewing angle is bonded to the display surface, display is performed. Since the stress applied to the device tends to adversely affect the display quality, the bonding resin layer preferably has a low elastic modulus.
Therefore, as a display device in a display device to which the curable resin composition of the present invention is applied, a liquid crystal display device is preferable, and an IPS type liquid crystal display device or a TN type liquid crystal display device is more preferable.

Further, a non-curable oligomer having 0.8 to 3 hydroxyl groups per molecule as a non-curable component that does not undergo a curing reaction with the curable compound (II) at the time of curing in the photo-curable resin composition for resin layer formation When a hydroxyl group that does not react at the time of curing is present in the curable compound (II), the storage shear elastic modulus can be reduced while suppressing an increase in loss tangent (tan δ) of the resin layer after curing. In addition, the photocurable resin composition for forming a resin layer when uncured has good stability, can have a low viscosity, and can achieve a uniform curing reaction during curing.
When the stability at the time of uncuring is good and the uniformity of the curing reaction at the time of curing is good, a resin layer with good transparency is easily obtained. When the viscosity of the photocurable resin composition for forming a resin layer when uncured is low, the generation of bubbles is easily suppressed, and a good interfacial bonding force between the face material and the resin layer is easily obtained.

In addition, the curable resin composition of this invention can be applied not only to a display apparatus but to the laminated body which laminated | stacked a pair of face material through the resin layer, and the same effect is acquired.
The curable resin composition of the present invention may be a thermosetting resin composition. In this case, a known thermosetting group is used as the curable group of the curable compound. Moreover, a well-known thermal polymerization initiator is contained as needed. In the said embodiment, when the curable resin composition for resin layer formation is thermosetting, it is preferable that the curable resin composition for seal part formation is also thermosetting.
In particular, a photo-curable resin composition is preferable in that it does not require a high temperature during curing, and therefore there is little risk of adverse effects on the face material and the like due to high temperatures.
By using a photopolymerization initiator and a thermal polymerization initiator in combination, photocuring and thermosetting can be performed simultaneously or separately to improve curability.
Moreover, the method of manufacturing a laminated body using the curable resin composition of this invention is not restricted to the method of the said embodiment, A well-known method can be used suitably.

  Below, the example implemented in order to confirm the effectiveness of this invention is shown. Examples 1-4, 8 and 9 are examples, and examples 5-7 are comparative examples.

(Measurement of storage shear modulus and loss tangent)
The storage shear modulus of the cured resin layer and its loss tangent (tan δ) are determined by using a rheometer (Physica MCR301, manufactured by Anton Paar Co., Ltd.) to form an uncured photocurable resin composition for resin layer formation using soda lime. A black light (Japan) sandwiched in a 0.4 mm gap between a glass stage and a measuring spindle (D-PP20 / AL / S07, manufactured by Anton Paar Co., Ltd.) at 35 ° C. under a nitrogen atmosphere. The photocurable resin composition for resin layer formation was measured by applying 1% dynamic shear strain while irradiating with light of 2 mW / cm2 for 30 minutes by FL15BL, manufactured by Denki Co., Ltd. When the photocurable resin composition for resin layer formation was cured, the position of the spindle was automatically adjusted so that no stress was generated in the normal direction of the spindle.
Irradiation intensity was measured on the stage where the photocurable resin composition for resin layer formation was installed using the illuminometer (Ushio Electric make, ultraviolet intensity meter unit meter UIT-101).

(Number average molecular weight)
The number average molecular weight of the oligomer was determined using a GPC apparatus (manufactured by TOSOH, HLC-8020).
(viscosity)
The viscosity of the photocurable resin composition was measured with an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., RE-85U).
(Haze value)
The haze value was determined by measurement according to ASTM D1003 using a haze guard II manufactured by Toyo Seiki Seisakusho.

[Example 1]
(Display device)
A liquid crystal display device was taken out from a commercially available 17-type liquid crystal monitor (Acer, V137b). In the liquid crystal display device, the display mode is a TN (twisted nematic) type, and the size of the display unit is 338 mm in length and 270 mm in width. Polarizing plates are bonded to both sides of the liquid crystal display device. Six FPCs for driving are bonded to one side of the long side, and three driving FPCs are bonded to one side of the short side. A printed wiring board was bonded to the. The liquid crystal display device was designated as display device A.

(Glass plate)
Frame-shaped by ceramic printing with black pigment so that the translucent part has a length of 340 mm and a width of 272 mm on the peripheral part of one surface of soda lime glass having a length of 355 mm, a width of 290 mm, and a thickness of 2.8 mm A light shielding printing part was formed, and a glass plate B serving as a protective plate was produced.

(Photo-curable resin composition for forming a seal part)
Bifunctional polypropylene glycol having two hydroxyl groups in one molecule with ethylene oxide added at the molecular end (number average molecular weight calculated from hydroxyl value: 4000, ethylene oxide content in polypropylene glycol molecule of 24% by mass), hexamethylene Diisocyanate is mixed at a molar ratio of 6 to 7, and then diluted with isobornyl acrylate (IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) and then reacted at 70 ° C. in the presence of a tin compound catalyst. 2-hydroxyethyl acrylate was added to the prepolymer at a molar ratio of about 1: 2, and 0.03 parts by mass of 2,5-di-t-butylhydroquinone (polymerization inhibitor) was added at 70 ° C. Urethane acrylate oligo diluted with 30% by weight isobornyl acrylate by reaction Chromatography (hereinafter, referred to as UC-1.) To obtain a solution. The number of curable groups of UC-1 was 2, and the number average molecular weight was about 55000. The viscosity of the UC-1 solution at 60 ° C. was about 580 Pa · s.

  90 parts by mass of the UC-1 solution and 10 parts by mass of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB) were uniformly mixed to obtain a mixture. 100 parts by mass of the mixture and 1 part by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 184) are uniformly mixed, and photocurability for forming a seal part Resin composition C was obtained.

  Defoaming treatment was performed by placing the photocurable resin composition C for forming a seal part in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . The viscosity at 25 ° C. of the photocurable resin composition C for forming a seal part was measured and found to be about 1300 Pa · s.

(Photocurable resin composition for resin layer formation)
Bifunctional polypropylene glycol having two hydroxyl groups in one molecule with ethylene oxide added at the molecular end (number average molecular weight calculated from hydroxyl value: 4000, ethylene oxide content in polypropylene glycol molecule of 24% by mass), and isophorone diisocyanate Are mixed at a molar ratio of 4 to 5, and 2-hydroxyethyl acrylate is added at a molar ratio of approximately 1: 2 to the prepolymer obtained by reacting at 70 ° C. in the presence of a tin compound catalyst. Then, 0.03 part by mass of 2,5-di-t-butylhydroquinone (polymerization inhibitor) was added and reacted at 70 ° C. to obtain a urethane acrylate oligomer (hereinafter referred to as UA-2). . The number of curable groups of UA-2 was 2, the number average molecular weight was about 24,000, and the viscosity at 25 ° C. was about 830 Pa · s.

  40 parts by mass of UA-2, 30 parts by mass of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB), and 30 parts by mass of n-dodecyl methacrylate were uniformly mixed. 0.5 parts by mass of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 819), n-dodecyl mercaptan (chain transfer agent, Kao) 0.5 part by mass of Thiocalcol 20) manufactured by the company was uniformly dissolved to obtain a photocurable resin composition PD.

  Next, 60 parts by mass of PD and the same bifunctional polypropylene glycol having two hydroxyl groups in one molecule whose molecular ends are modified with ethylene oxide, as used in the synthesis of UA-2 (calculated from the hydroxyl value) 40 parts by mass of a number average molecular weight of 4000 and an ethylene oxide content of 24% by mass in a polypropylene glycol molecule) was uniformly dissolved to obtain a photocurable resin composition D for resin layer formation.

Defoaming treatment was performed by placing the photocurable resin composition D for resin layer formation in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 1.7 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition D for resin layer formation was measured.
The photopolymerization initiator (IRGACURE 819) used for the photocurable resin composition D for resin layer formation is the photopolymerization initiator (IRGACURE 184) used for the photocurable resin composition C for seal portion formation. The absorption wavelength region (about 440 nm or less) is also present on the longer wavelength side than the absorption wavelength region (about 380 nm or less).
Next, when the viscoelastic property after photocuring of the photocurable resin composition D for resin layer formation was measured using a rheometer, the storage shear modulus was 1.0 × 10 ⁴ Pa, its loss tangent (tan δ). ) Was 0.83.

(Process (a))
The photocurable resin composition C for forming a seal portion is applied with a dispenser so as to have a width of about 1 mm and a coating thickness of about 0.6 mm over the entire circumference at a position of about 4 mm outside the image display area of the display device A. Then, an uncured seal portion was formed.

(Process (b))
A plurality of photocurable resin compositions D for resin layer formation are applied to the inner region of the uncured seal portion applied to the outer periphery of the image display region of the display device A using a dispenser so that the total mass becomes 38 g. Supply to the place.
While the photocurable resin composition D for resin layer formation was supplied, the shape of the uncured seal portion was maintained.

(Process (c))
The display device A was placed flat on the upper surface of the lower surface plate in the decompression device in which a pair of surface plate lifting devices were installed so that the surface of the photocurable resin composition D for resin layer formation was on top.
When the glass plate B is viewed from the upper surface using an electrostatic chuck on the lower surface of the upper surface plate of the lifting device in the decompression device so that the surface on the side where the light-shielding printing portion is formed faces the display device A Further, the distance between the light transmitting portion of the glass plate B and the display device A and the image display area of the display device A is the same position with a margin of about 1 mm so that the distance from the display device A is 30 mm in the vertical direction. Held.

The decompression device was sealed and evacuated until the pressure in the decompression device reached about 10 Pa. The upper and lower surface plates are brought close to each other by the lifting device in the decompression device, and the display device A and the glass plate B are pressure-bonded at a pressure of 2 kPa through the photocurable resin composition D for resin layer formation and held for 1 minute. It was. Static electricity is removed from the electrostatic chuck, the glass plate B is separated from the upper surface plate, the pressure reducing device is returned to atmospheric pressure in about 15 seconds, and the light for forming the resin layer is formed by the display device A, the glass plate B, and the uncured seal portion. A lamination precursor E in which the curable resin composition D was sealed was obtained.
In the laminated precursor E, the shape of the uncured seal portion was maintained in an almost initial state.

(Process (d))
An ultraviolet LED is linearly arranged from the side of the display device A to an uncured seal portion (photocurable resin composition C for forming a seal portion) provided on the peripheral edge portion of the display device A of the laminated precursor E. Using an ultraviolet light source (Spec. Illumination LL146-395), light was irradiated over the entire circumference of the uncured seal portion for about 10 minutes to cure the seal portion. It was about 1 mW / cm < ² > when the intensity | strength of irradiated light was measured with the illuminance meter (The Oak Seisakusho company make, UV-M02, light receiver UV-42). After the seal was cured, the lamination precursor E was kept horizontal and allowed to stand for about 10 minutes.

  By uniformly irradiating UV light from a black light and visible light of 450 nm or less from the surface of the laminated precursor E on the glass plate B side for 30 minutes to cure the photocurable resin composition D for resin layer formation, A resin layer was formed, and display device F was obtained. Although the display device F does not require the step of removing bubbles necessary for manufacturing by the conventional injection method, defects such as bubbles remaining in the resin layer were not confirmed. In addition, defects such as leakage of the photocurable resin composition for resin layer formation from the seal portion were not confirmed. Moreover, the thickness of the resin layer was a target thickness (about 0.4 mm).

  A transparent laminate was prepared in the same manner using a glass plate of almost the same size in place of the display device A, and the haze value in a portion without the printing light-shielding portion was measured. Met.

The display device F was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Subsequently, the display device F was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 2]
(Photocurable resin composition for resin layer formation)
40 parts by mass of UA-2 used in Example 1, 30 parts by mass of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB), and 30 parts by mass of n-dodecyl methacrylate were uniformly mixed. In 100 parts by mass, 0.5 part by mass of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 819) was uniformly dissolved. A photocurable resin composition PG was obtained.

  Next, 40 parts by mass of PG and the same bifunctional polypropylene glycol having two hydroxyl groups in one molecule modified with ethylene oxide, the same as that used in the synthesis of UA-2 (calculated from the hydroxyl value) The photocurable resin composition G for resin layer formation was obtained by uniformly dissolving 60 parts by mass of a number average molecular weight of 4000 and an ethylene oxide content of 24% by mass in a polypropylene glycol molecule.

The defoaming treatment was performed by placing the photocurable resin composition G for resin layer formation in a decompression apparatus in an open state while being placed in a container, and reducing the pressure in the decompression apparatus to about 20 Pa and holding for 10 minutes. . It was 1.3 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition G for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition G for resin layer formation was measured using a rheometer, the storage shear modulus was 3.7 × 10 ³ Pa, and its loss tangent (tan δ). ) Was 0.61.

Display device H as in Example 1 except that Composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and Composition G was used as the photocurable resin composition for forming the resin layer. Got.
The display device H was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Next, the display device H was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 3]
(Photocurable resin composition for resin layer formation)
Bifunctional polypropylene glycol having two hydroxyl groups in one molecule with ethylene oxide added at the molecular end (number average molecular weight calculated from hydroxyl value: 4000, ethylene oxide content in polypropylene glycol molecule of 24% by mass), and isophorone diisocyanate Are mixed at a molar ratio of 3 to 4, and 2-hydroxyethyl acrylate is added at a molar ratio of approximately 1: 2 to the prepolymer obtained by reacting at 70 ° C. in the presence of a tin compound catalyst. Then, 0.03 part by mass of 2,5-di-t-butylhydroquinone (polymerization inhibitor) was added and reacted at 70 ° C. to obtain a urethane acrylate oligomer (hereinafter referred to as UA-3). . The number of curable groups of UA-3 was 2, the number average molecular weight was about 21,000, and the viscosity at 25 ° C. was about 350 Pa · s.

  80 parts by weight of UA-3 and 20 parts by weight of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB) are mixed with 100 parts by weight of the mixture, and bis (2,4,6-trimethylbenzoyl) -0.5 part by mass of phenylphosphine oxide (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 819) was uniformly dissolved to obtain a photocurable resin composition PI.

  Next, 30 parts by mass of PI and 70 of bifunctional polypropylene glycol having two hydroxyl groups in one molecule (number average molecular weight calculated from hydroxyl value: 2000, EO content in polypropylene glycol of 0% by mass) Mass parts were uniformly dissolved to obtain a photocurable resin composition I for resin layer formation.

Defoaming treatment was performed by placing the photocurable resin composition I for resin layer formation in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 2.0 Pa * s when the viscosity at 25 degrees C of the photocurable resin composition I for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition I for resin layer formation was measured using a rheometer, the storage shear modulus was 2.5 × 10 ⁴ Pa, and its loss tangent (tan δ). ) Was 0.06.

A display device J was prepared in the same manner as in Example 1 except that the composition C was used as the photocurable resin composition for forming a seal portion as in Example 1 and the composition I was used as the photocurable resin composition for forming a resin layer. Got.
The display device J was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, the wiring was reconnected, and then the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Subsequently, the display device J was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 4]
(Photocurable resin composition for resin layer formation)
20 parts by mass of PI used in Example 3 and bifunctional polypropylene glycol having two hydroxyl groups in one molecule (number average molecular weight calculated from hydroxyl value: 2000, EO content in polypropylene glycol of 0% by mass) Was uniformly dissolved to obtain a photocurable resin composition I2 for forming a resin layer.

The photocurable resin composition I2 for resin layer formation was placed in a decompression device in an open state while being placed in a container, and the defoaming treatment was performed by reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 1.0 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition I2 for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition I2 for resin layer formation was measured using a rheometer, the storage shear modulus was 4.0 × 10 ³ Pa, its loss tangent (tan δ). ) Was 0.07.

The display device J2 was the same as Example 1 except that the composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and the composition I2 was used as the photocurable resin composition for forming the resin layer. Got.
The display device J2 was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, the wiring was reconnected, and then the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Subsequently, the display device J2 was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 5]
(Photocurable resin composition for resin layer formation)
40 parts by mass of UA-2 used in Example 1, 20 parts by mass of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB), and 40 parts by mass of n-dodecyl methacrylate were uniformly mixed. In 100 parts by mass, 0.3 part by mass of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 819), 2,5-di -0.04 parts by mass of t-butylhydroquinone (polymerization inhibitor), 0.5 parts by mass of n-dodecyl mercaptan (chain transfer agent, Kao Corporation, thiocalcol 20), UV absorber (Ciba Specialty Chemicals) Manufactured by TINUVIN 109) is uniformly dissolved to obtain a photocurable resin composition K for resin layer formation. .

Defoaming treatment was performed by placing the photocurable resin composition K for resin layer formation in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 2.0 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition K for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition K for resin layer formation was measured using a rheometer, the storage shear modulus was 1.6 × 10 ⁵ Pa, and its loss tangent (tan δ). ) Was 0.44.

The display device L was the same as in Example 1 except that the composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and the composition K was used as the photocurable resin composition for forming the resin layer. Got.
The display device L was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, display unevenness occurred in a part of the display screen, and it was visually recognized especially at the peripheral portion of the display screen in the halftone display. In a portion having no display unevenness, an image having a higher contrast than that in the initial stage was obtained.
Subsequently, the display device L was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no positional shift and the glass plate was held well.

[Example 6]
(Photocurable resin composition for resin layer formation)
The photocurable resin composition PG used in Example 2 was used as the photocurable resin composition M for resin layer formation.

Defoaming treatment was performed by placing the photocurable resin composition M for resin layer formation in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 2.2 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition M for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition M for resin layer formation was measured using a rheometer, the storage shear modulus was 3.1 × 10 ⁵ Pa, and its loss tangent (tan δ). ) Was 0.32.

A display device N was prepared in the same manner as in Example 1 except that the composition C was used as the photocurable resin composition for forming a seal portion as in Example 1 and the composition M was used as the photocurable resin composition for forming a resin layer. Got.
The display device N was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, display unevenness occurred in a part of the display screen, and it was particularly noticeable at the peripheral edge of the display screen in the halftone display. In a portion having no display unevenness, an image having a higher contrast than that in the initial stage was obtained.
Subsequently, the display device N was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 7]
(Photocurable resin composition for resin layer formation)
40 parts by mass of UA-2 used in Example 1, 20 parts by mass of 2-hydroxybutyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., light ester HOB), and 40 parts by mass of n-dodecyl methacrylate were uniformly mixed. To 100 parts by mass, 0.3 part by mass of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (photopolymerization initiator, manufactured by Ciba Specialty Chemicals, IRGACURE 819), n-dodecyl mercaptan ( 1.5 parts by mass of a chain transfer agent, manufactured by Kao Corporation, thiocalcol 20) was uniformly dissolved to obtain a photocurable resin composition O for resin layer formation.

Defoaming treatment was performed by placing the photocurable resin composition O for resin layer formation in a decompression device in an open state while being placed in a container, and reducing the pressure in the decompression device to about 20 Pa and holding for 10 minutes. . It was 1.9 Pa.s when the viscosity at 25 degrees C of the photocurable resin composition O for resin layer formation was measured.
Next, when the viscoelastic property after photocuring of the photocurable resin composition O for resin layer formation was measured using a rheometer, the storage shear modulus was 7.5 × 10 ³ Pa, its loss tangent (tan δ). ) Was 1.8.
The display device P was prepared in the same manner as in Example 1 except that the composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and the composition O was used as the photocurable resin composition for forming the resin layer. Got.
The display device P was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. After confirming the bonding position of the display device after about 1 hour, it was displaced from the glass plate by about several mm, and the display device could not be satisfactorily held on the glass plate.
Therefore, when the display device P is installed so that the display device A bonded to the glass plate B is horizontal, the display device P is left to stand for 5 days, and then the power is turned on. A uniform and good display image was obtained at the part, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.

[Example 8]
In Example 1, bifunctional polypropylene glycol having two hydroxyl groups in one molecule in which ethylene oxide is not added to the molecular end instead of bifunctional polypropylene glycol in which ethylene oxide is added to the molecular end is used for the synthesis of UA-2. A number average molecular weight of 5500 calculated by the hydroxyl value) and a mixture containing almost the same amount of 2,2,4-trimethyl-hexamethylene diisocyanate and 2,4,4-trimethyl-hexamethylene diisocyanate in a mole of 1: 2. A urethane acrylate oligomer (UA-4) was synthesized in the same manner as in Example 1 except that the ratio was mixed. The number of curable groups of UA-4 was 2, the number average molecular weight was about 16000, and the viscosity at 25 ° C. was about 39 Pa · s.
In Example 1, UA-4 is used instead of UA-2, and a photocurable resin composition PQ for resin layer formation is obtained in the same manner as in Example 1. 40 parts by mass of PQ and the same bifunctional polypropylene glycol having two hydroxyl groups in one molecule that does not add ethylene oxide at the molecular ends, as used for the synthesis of UA-4 (number average calculated by hydroxyl value) The photocurable resin composition Q for resin layer formation is obtained using molecular weight 5500). The viscosity at 25 ° C. of the photocurable resin composition Q for resin layer formation was 0.8 Pa · s.
The viscoelastic properties after photocuring of the photocurable resin composition Q for resin layer formation using a rheometer were as follows: the storage shear modulus was 2.4 × 10 ⁴ Pa, and the loss tangent (tan δ) was 0.13. .
The display device R was the same as in Example 1 except that the composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and the composition Q was used as the photocurable resin composition for forming the resin layer. Got.
The display device R was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Subsequently, the display device R was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no position shift and the glass plate was held well.

[Example 9]
Other than mixing bifunctional polypropylene glycol (number average molecular weight 2000 calculated by hydroxyl value) having 2 hydroxyl groups in one molecule not adding ethylene oxide at the molecular end and isophorone diisocyanate in a molar ratio of 5: 6 In the same manner as in Example 1, a urethane acrylate oligomer (UA-5) was synthesized. The number of curable groups of UA-5 was 2, the number average molecular weight was about 18000, and the viscosity at 25 ° C. was about 620 Pa · s.
In Example 1, using UA-5 instead of UA-2, a photocurable resin composition PS for resin layer formation is obtained in the same manner as in Example 1. 40 parts by mass of PS and the same bifunctional polypropylene glycol having two hydroxyl groups in one molecule that does not add ethylene oxide at the molecular end, as used for the synthesis of UA-5 (number average calculated by hydroxyl value) Bifunctional polypropylene glycol having a molecular weight of 2000) and 2 hydroxyl groups in one molecule not adding ethylene oxide to a molecular end having a molecular weight larger than that used for the synthesis of UA-5 (calculated by hydroxyl value) The photocurable resin composition S for resin layer formation is obtained using 30 parts by mass of a number average molecular weight of 5500). The viscosity of the photocurable resin composition S for resin layer formation at 25 ° C. was 0.9 Pa · s.
The viscoelastic properties after photocuring of the photocurable resin composition S for resin layer formation using a rheometer were as follows: the storage shear modulus was 2.0 × 10 ⁴ Pa, and the loss tangent (tan δ) was 0.15. .
The display device T was prepared in the same manner as in Example 1 except that the composition C was used as the photocurable resin composition for forming the seal portion as in Example 1 and the composition S was used as the photocurable resin composition for forming the resin layer. Got.
The display device T was returned to the housing of the liquid crystal monitor from which the liquid crystal display device was taken out, and after reconnecting the wiring, the liquid crystal monitor was installed so that the display device A joined to the glass plate B was vertical. When the power was turned on after standing for 5 days, a uniform and good display image was obtained over the entire display screen, and the display contrast was high from the beginning. Even if the image display surface was strongly pressed with a finger, the image was not disturbed, and the glass plate B effectively protected the display device A.
Subsequently, the display device T was installed in the same manner, and the bonding position of the display device was confirmed one month later. However, there was no positional shift and the glass plate was held well.

Examples 1-4, 8 and 8 containing the curable compound (II) of the present invention and the non-curable oligomer (D), wherein the content of the (D) is 10 to 90% by mass in the curable resin composition. No. 9 can reduce stress due to shrinkage during curing of the resin layer, and a uniform and good display image can be obtained over the entire surface of the liquid crystal display screen.
In Examples 5 and 6 which contain the curable compound (II) of the present invention but do not contain the non-curable oligomer (D), display unevenness occurs in the peripheral portion of the liquid crystal display screen, and is particularly noticeable in halftone display. It was visually recognized. In particular, Example 7 containing a chain transfer agent in excess of 1.0 part by mass with respect to 100 parts by mass of the curable compound (II) failed to hold the display device well on the glass plate.

The curable resin composition of this invention is useful for manufacture of the laminated body used for a display apparatus.
It should be noted that the entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2010-137551 filed on June 16, 2010 is cited herein as the disclosure of the specification of the present invention. Incorporated.

DESCRIPTION OF SYMBOLS 1 Display apparatus 10 Transparent surface material 12 Uncured sealing part 13 Area | region 14 Photocurable resin composition for resin layer formation 40 Resin layer 42 Sealing part 50 Display device 55 Light-shielding printing part (light-shielding part)
56 Translucent part

Claims (5)

The storage shear modulus in the dynamic viscoelasticity measurement after curing used for laminating a pair of face materials is 5 × 10 ^{2 to} 2.5 × 10 ⁴ Pa, and the loss tangent is 0.01 to 0. A resin layer made of a cured product of a photocurable curable resin composition, which is a curable resin composition of .83, which includes a photocurable curable compound and a non-curable oligomer . The resin layer according to claim 1, wherein the curable compound includes one or more oligomers having a curable group and one or more monomers having a curable group. The resin layer of Claim 2 whose content rate of the oligomer which has the said sclerosing | hardenable group is 20-90 mass% among the whole (100 mass%) of the said curable compound. One of the pair of face materials is a transparent face material, and the other is a display device,
Storage shear modulus in a dynamic viscoelasticity measurement after curing is ^{5 × 10 2 ~2.5 × 10 4} Pa, and the loss tangent is a curable resin composition is 0.01 to 0.83 A display device comprising a laminate in which the pair of face members are laminated with a resin layer made of a cured product of a photocurable curable resin composition containing a photocurable curable compound and a non-curable oligomer .   The display device according to claim 4, wherein the display device is a liquid crystal display device.

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