WO2012081708A1 - Photocurable resin composition, and image display device and process for production thereof - Google Patents

Abstract

The present invention provides: a photocurable resin composition whereby it becomes possible to allow the curing of a light-shielding part to proceed satisfactorily only by the exposure to a light-transmissive part; an image display device produced using the photocurable resin composition; and others. This photocurable resin composition comprises (A) an oligomer having two or more ethylenically unsaturated bonds in the molecule, (B) a plasticizer, (C) a photopolymerization initiator, and (D) a thiol compound represented by general formula (1). (In general formula (1), R¹ and R² independently represent a hydrogen atom or an alkyl group having 1-5 carbon atoms; m represents an integer of 0-3; n represents an integer of 1-6; and A represents an n-valent organic group.

Description

Photocurable resin composition, image display device, and method for producing the same

The present invention relates to a photocurable resin composition that is useful for preventing cracking of an image display device, relaxing stress and impact, and having excellent transparency, an image display device using this composition, and a method for producing the same. .

A liquid crystal display device is exemplified as a typical image display device equipped with an image display panel. The liquid crystal display device has a liquid crystal display panel composed of a liquid crystal cell and an optical film such as a polarizing plate attached to both outer surfaces thereof. In this liquid crystal cell, two glass substrates having a thickness of about 1 mm with transparent electrodes and pixel patterns formed on the surface are arranged with a gap of about several microns, and liquid crystal is filled and sealed in the gap. It will be.
The liquid crystal display panel is thin and easily scratched. In particular, in mobile phones, game consoles, digital cameras, in-vehicle applications, etc., a transparent front panel (protective panel) with a certain space in front of the liquid crystal display panel In general, a liquid crystal display device having a structure is provided.
Furthermore, in recent years, touch panels have been mounted on mobile phones, game machines, digital cameras, in-vehicle parts, and image display devices such as notebook personal computers, desktop personal computers, and personal computer monitors. An image display device equipped with such a touch panel has a laminated structure of a front panel, a touch panel, and a liquid crystal display panel. Air is interposed between the front panel and the touch panel, and between the touch panel and the liquid crystal display panel. Intervene. These airs cause light scattering, resulting in a decrease in contrast and brightness.
Further, as a current large-sized liquid crystal display device, an anti-glare (AG) treatment is generally performed on the surface of the front polarizing plate of the liquid crystal display device to reduce reflection. This large-sized liquid crystal display device has no means for shock absorption on the AG-treated surface, and has an impact resistance with a structure as a whole liquid crystal display panel and a set of liquid crystal display devices.
Problems with the large-sized liquid crystal display device with this configuration are that the image looks blurred due to AG processing, the liquid crystal display panel is distorted when touched on the surface, and the stain is difficult to remove due to AG processing. In addition to the tendency to become large, it is conceivable that the impact resistance of the liquid crystal display panel is lowered with the future enlargement of the liquid crystal display panel.
In view of this, it is conceivable that a front plate subjected to anti-reflection (AR) processing is placed in front of the liquid crystal display panel to eliminate the disadvantages caused by AG processing.
In this case, if the space between the front plate and the liquid crystal display panel is air, a decrease in transmittance, a decrease in image quality due to double projection, and the like can be considered. Therefore, it has been proposed to fill the space with a resin or the like. (For example, see Patent Documents 1 to 4).

However, the oil used in Patent Document 1 is difficult to seal to prevent leakage, may damage the material used in the liquid crystal panel, and the oil leaks when the front plate is cracked, etc. There is a problem.
Further, the unsaturated polyester of Patent Document 2 is easy to be colored yellow, and application to a liquid crystal display device is not desirable.
The silicone of Patent Document 3 has a low adhesive force and requires a separate pressure-sensitive adhesive for fixing, and the process becomes complicated. Further, since the adhesive force with the pressure-sensitive adhesive is not so large, it peels off when an impact is applied. There is a problem that air bubbles enter.
The polymer of the acrylic monomer of Patent Document 4 has a low adhesive force and does not require a separate adhesive for small devices, but a separate adhesive is required to support the front plate of a large liquid crystal display device. The process becomes complicated. In addition, since the raw material is composed only of the monomer, the viscosity is low, and the curing shrinkage is large, so that it is difficult to uniformly produce a film having a large area.
In addition, glass cathode ray tubes (CRTs) are determined not to scatter or penetrate through an impact resistance test by dropping a steel ball according to UL standards or radio wave control methods for televisions and displays. Therefore, in order to satisfy this standard, it is necessary to design the CRT glass to be thick, and the weight of the CRT is increased.
Then, the method of laminating | stacking the synthetic resin protective film which has a self-restoration property on glass as a means to give scattering prevention property without making glass thick is proposed (for example, refer patent document 5).
However, this method is characterized by scattering prevention, but does not have a function of preventing glass from breaking.
On the other hand, the PDP, which is one of the flat panel displays (FPDs), has a space of about 1 to 5 mm from the PDP to prevent cracking of the PDP, and a front plate such as glass with a thickness of about 3 mm on the front (viewing surface). Side). For this reason, as the PDP is increased in size, the area of the front plate is increased, so that the PDP becomes heavy.
Therefore, in order to prevent cracking of the display, it has been proposed to laminate a specific resin on the display surface or to laminate an optical filter on which the specific resin is laminated (see, for example, Patent Documents 6 to 8). ).
However, in Patent Documents 6 and 7, there is no particular consideration regarding the composition of the resin material to be used, and the means for expressing adhesiveness and transparency is unclear.
In particular, in Patent Document 6, there is no sufficient consideration regarding the moisture resistance reliability of the resin, and the resin material having the composition specifically shown in the examples becomes cloudy in a short time moisture resistance test after being applied to a display.
Also in Patent Document 7, since acrylic acid is used as a part of the resin specifically shown in the examples, the resin becomes cloudy in a long-time moisture resistance test and is in contact during the moisture resistance test. The problem of corroding the metal occurs.
Furthermore, in patent documents 7 and 8, it is thought that examination is inadequate from a viewpoint of obtaining the more outstanding impact absorbability.
In Patent Document 7, the thickness of the impact-resistant layer using a resin is set to 0.2 to 1 mm, but there is no disclosure from the viewpoint of increasing the thickness to further improve the impact absorbability.
In Patent Document 8, consideration is given to heat-and-moisture resistance, but the resin material composition described in Patent Document 8 cannot be expected to significantly improve impact resistance. Moreover, the thickness of the resin layer in an Example is 1 mm, and it is thought that examination is inadequate from a viewpoint of obtaining the more excellent impact absorbability.
In addition, as described in the example of Patent Document 8, if a soft resin after curing is used thickly, the surface hardness of the front filter is lowered, which may cause a problem in scratch resistance. Conceivable.

JP 05-011239 A Japanese Patent Laid-Open No. 03-204616 Japanese Patent Laid-Open No. 06-059253 JP 2004-125868 A Japanese Patent Laid-Open No. 06-333515 JP 2004-058376 A JP 2005-107199 A JP 2004-263084 A

Resin composition for filling a space as described above (for example, a space between a protective panel and an image display unit, a space between a protective panel and a touch panel, and a space between a touch panel and an image display unit) of an image display device. As mentioned above, when a thermosetting resin composition is used, it is subject to restrictions on the heat resistance temperature as a constituent member of the image display device. Therefore, the use of a photocurable resin composition as a resin composition for filling the space of the image display device has been studied.
By the way, in the image display device, for the purpose of improving the contrast of a display image, a frame-shaped light shielding portion having a predetermined width is provided along the outer peripheral edge of the protective panel. The light shielding unit has a function of blocking unnecessary light around the image display panel and preventing deterioration of display quality due to light leakage.
However, when the light shielding part is provided on the protective panel, there is a problem that sufficient light does not reach the photocurable resin composition filled in the space behind the light shielding part, thereby hindering curing.
For example, when a protective panel is arranged on an image display unit in which a liquid crystal display panel is incorporated in a frame, a photocurable resin composition is filled between them, and light is irradiated from the protective panel side, the light is emitted from the frame Therefore, the light passes through the inner part (light transmission part) of the frame of the protective panel. For this reason, the photocurable resin composition on the back side of the frame is not sufficiently irradiated with light, and curing may not sufficiently proceed.
If the resin composition is not sufficiently cured, the quality of the image display device will be greatly impaired, which will be a major factor in reducing the reliability.

The present invention is a photo-curable resin composition that can sufficiently cure a shadow part (hereinafter sometimes simply referred to as “light-shielding part”) such as a back side part of a light-shielding part only by exposure to a light transmission part. It is an object of the present invention to provide an image display device using the photocurable resin composition and a method for producing the same.

The photocurable resin composition of the present invention comprises (A) an oligomer having two or more ethylenically unsaturated bonds in the molecule, (B) a plasticizer, (C) a photopolymerization initiator, and (D) It contains the thiol compound represented by Formula (1), It is characterized by the above-mentioned.

(In the general formula (1), R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m represents an integer of 0 to 3, and n represents an integer of 1 to 6) A represents an n-valent organic group.)
According to the present invention, the light-shielding portion that is not exposed to light in the photocurable resin composition can be cured.
The photocurable resin composition is preferably a urethane oligomer in which the component (A) has two or more (meth) acryloyl groups. Thereby, sclerosis | hardenability, adhesiveness, and elongation can be made more excellent.
The photocurable resin composition is preferably a urethane oligomer in which the component (B) does not have an ethylenically unsaturated bond or has one in the molecule. Thereby, the hardening width property of a light-shielding part can be made more excellent.
The photocurable resin composition preferably contains substantially no organic solvent and has a viscosity at 25 ° C. of 500 to 5000 mPa · s. Thereby, bleed-out can be suppressed and moisture-heat reliability can be further improved.
In the method for producing an image display device of the present invention, an image display unit having an image display unit and a protective panel are arranged to face each other, and the photocurable resin composition is interposed between the image display unit and the photocurable resin. A method for manufacturing an image display device for curing a composition, wherein the protective panel has a light-shielding portion along an outer peripheral edge, and a photocurable resin composition between the image display unit and the protective panel. On the other hand, light irradiation is performed at least from the protective panel side.
The image display device of the present invention is manufactured by the manufacturing method.

According to the present invention, it is possible to provide a photocurable resin composition that can sufficiently cure the light-shielding portion, an image display device using the photocurable resin composition, and a method for manufacturing the same.

It is side surface sectional drawing which shows typically one Embodiment of the liquid crystal display device of this invention. 1 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of the liquid crystal display device of the present invention.

Hereinafter, the photocurable resin composition of the present invention, a method for producing an image display device using the same, and an image display device will be described in detail by embodiments. In addition, this invention is not limited by this embodiment.
In this specification, “(meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” and “methacryl” corresponding thereto, and “(meth) acryloyl” means “acryloyl” and corresponding “methacryloyl”.

[Photocurable resin composition]
The photocurable resin composition according to the present invention comprises (A) an oligomer having two or more ethylenically unsaturated bonds in the molecule, (B) a plasticizer, (C) a photopolymerization initiator, and (D) A thiol compound represented by formula (1).

(In the general formula (1), R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m represents an integer of 0 to 3, and n represents an integer of 1 to 6) A represents an n-valent organic group.)
Hereinafter, each component will be described.

<(A) component: an oligomer having two or more ethylenically unsaturated bonds in the molecule>
(A) As an oligomer having two or more ethylenically unsaturated bonds in the molecule, for example, a polyester oligomer having two or more (meth) acryloyl groups, a urethane oligomer having two or more (meth) acryloyl groups, polyethylene Examples include glycol di (meth) acrylate and polyprolene glycol di (meth) acrylate. These can be used alone or in combination of two or more.
Among these, in particular, a viewpoint of balance of various properties (for example, viscosity stability, curability, wet heat resistance reliability, light-curing portion curability, transmittance, haze, curing shrinkage, adhesiveness, elongation, reworkability, etc.) Therefore, a urethane oligomer having two or more (meth) acryloyl groups is preferable, and a urethane oligomer having two (meth) acryloyl groups is more preferable from the viewpoint of curing shrinkage.

(Production method 1 of component (A))
(A) The urethane oligomer having two or more (meth) acryloyl groups is, for example, a compound obtained by reacting (a1) a diol compound and (a2) a compound having an isocyanate group (hereinafter referred to as a urethane oligomer). In some cases) can be obtained by reacting a compound for introducing a (meth) acryloyl skeleton.
As a compound for introducing the (meth) acryloyl skeleton, (a3) monohydroxy (meth) acrylate, (a4) monocarboxylic acid having (meth) acryloyl group, and (a5) having (meth) acryloyl group It is preferable to use a monoisocyanate compound.

[(A1) Diol Compound]
(A1) Examples of the diol compound include polyether diols such as polyethylene glycol and polypropylene glycol, polybutadiene diols, polyisoprene diols, hydrogenated polybutadiene diols, hydrogenated polyisoprene diols and other polyolefin diols, polyester diols, polycaprolactone diols, Examples thereof include silicone diol. Among these, polyether diol is preferable from the viewpoint of stress / impact relaxation, transparency, and adhesiveness, and polypropylene glycol is more preferable.

[(A2) Compound having an isocyanate group]
As said (a2) compound which has an isocyanate group, the diisocyanate compound represented by following General formula (2) is mentioned, for example.

(In general formula (2), X represents a divalent organic group.)
Examples of the divalent organic group represented by X in the general formula (2) include, for example, an alkylene group having 1 to 20 carbon atoms; unsubstituted or substituted with a lower alkyl group having 1 to 5 carbon atoms such as a methyl group. Arylene groups such as phenylene group, naphthylene group, xylylene group, diphenylmethane-4,4′-diyl group, diphenylsulfone-4,4′-diyl group; hydrogenated diphenylmethane-4,4′-diyl group, etc. It is done.
The number of carbon atoms of the alkylene group is more preferably 1-18, and still more preferably 6-12.

Examples of the diisocyanates represented by the general formula (2) include diphenylmethane-2,4′-diisocyanate; 3,2′-, 3,3′-, 4,2′-, 4,3′-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3'-, 4,2'- 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate; 3,2'-, 3,3 ' -, 4,2'-, 4,3'-, 5,2'-, 5,3'-, 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate; diphenylmethane-4 , 4′-diisocyanate; diphenylmethane-3,3′-diisocyanate; diphenylmethane-3,4′-diisocyanate, etc. Examples thereof include nylmethane diisocyanate compounds and hydrogenated products thereof. The diisocyanates represented by the general formula (2) include diphenyl ether-4,4′-diisocyanate; benzophenone-4,4′-diisocyanate; diphenylsulfone-4,4′-diisocyanate; tolylene-2,4- Diisocyanate; Tolylene diisocyanate such as tolylene-2,6-diisocyanate; m-xylylene diisocyanate; p-xylylene diisocyanate; 1,5-naphthalene diisocyanate; 4,4 ′-[2,2-bis (4-phenoxyphenyl) ) Propane] diisocyanate; aromatic isocyanate compounds. Furthermore, the diisocyanates represented by the general formula (2) include hexamethylene diisocyanate; trimethylhexamethylene diisocyanate such as 2,2,4-trimethylhexamethylene diisocyanate; isophorone diisocyanate; 4,4′-dicyclohexylmethane diisocyanate; Examples include cyclohexane-1,4-diisocyanate; hydrogenated m-xylylene diisocyanate; and aliphatic or alicyclic isocyanates such as lysine diisocyanate. As these diisocyanates, it is preferable to use an aliphatic diisocyanate compound in which X in the general formula (2) is a group having an aliphatic group. These can be used alone or in combination of two or more. Of these, trimethylhexamethylene diisocyanate is more preferably used alone or in combination with the above isocyanates, and trimethylhexamethylene diisocyanate is more preferably used alone. In addition, as a compound which has an isocyanate group, you may use trifunctional or more polyisocyanate with the diisocyanate represented by General formula (2).

Moreover, the diisocyanates represented by the general formula (2) may be those stabilized with a blocking agent necessary to avoid changes over time. Examples of the blocking agent include hydroxy acrylate, alcohol typified by methanol, phenol, oxime and the like, but there is no particular limitation.

[Blending ratio of (a1) diol compound and (a2) compound having an isocyanate group]
The blending ratio when the above (a1) diol compound and (a2) the compound having an isocyanate group are reacted is the number average molecular weight of the urethane oligomer to be produced, and the end of the urethane oligomer to be produced is a hydroxyl group or an isocyanate group. It is adjusted appropriately depending on whether or not.

When the terminal of the urethane oligomer is an isocyanate group, (a1) a diol compound and (a2) a compound having an isocyanate group so that the ratio of the number of isocyanate groups to the number of hydroxyl groups (isocyanate group / hydroxyl group number) is 1.01 or more. Is preferably adjusted, and from the viewpoint of increasing the number average molecular weight, it is preferably adjusted to less than 2. By setting such a ratio, a urethane oligomer having an isocyanate group at the end can be obtained.
Thus, in the case of the urethane oligomer whose terminal is an isocyanate group, examples of the compound for introducing the (meth) acryloyl skeleton include (a3) monohydroxy (meth) acrylate compound.

On the other hand, when the terminal of the urethane oligomer is a hydroxyl group, it has (a1) a diol compound and (a2) an isocyanate group so that the ratio of the number of hydroxyl groups to the number of isocyanate groups (number of hydroxyl groups / number of isocyanate groups) is 1.01 or more. It is preferable to adjust the blending ratio with the compound, and it is preferable to adjust it to less than 2 from the viewpoint of increasing the number average molecular weight.
Thus, in the case of a urethane oligomer having a terminal hydroxyl group, the compound for introducing the (meth) acryloyl skeleton has (a4) monocarboxylic acids having a (meth) acryloyl group or (a5) a (meth) acryloyl group. By using a compound capable of reacting with a hydroxyl group such as a monoisocyanate compound and reacting these compounds with the hydroxyl group at the terminal of the urethane oligomer, a urethane oligomer having two (meth) acryloyl groups can be obtained.

[(A3) Monohydroxy (meth) acrylate]
Examples of the (a3) monohydroxy (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 1,4-cyclohexanedimethanol. Mono (meth) acrylate, caprolactone or alkylene oxide adduct of each of the above (meth) acrylates, glycerin di (meth) acrylate, trimethylol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) Examples thereof include acrylate, ditrimethylolpropane tri (meth) acrylate, and 2-acryloxyethanol. Of these, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate are preferred, 2-hydroxyethyl (meth) acrylate is more preferred, and 2-hydroxyethyl Acrylate is more preferred. These monohydroxy compounds can be used alone or in combination of two or more.

[(A4) Monocarboxylic acids having a (meth) acryloyl group]
(A4) Examples of monocarboxylic acids having a (meth) acryloyl group include (meth) acrylic acid.
[(A5) Monoisocyanate compound having (meth) acryloyl group]
(A5) Examples of the monoisocyanate compound having a (meth) acryloyl group include 2-isocyanate ethyl (meth) acrylate.

(Production method 2 of component (A))
Moreover, the urethane polymer which has a (meth) acryloyl group can also be manufactured by methods other than the above.
As other methods for producing a urethane polymer having a (meth) acryloyl group, for example, a predetermined amount of (a1) diol compound and (a3) monohydroxy (meth) acrylate are mixed, and the temperature is raised to a predetermined temperature. Then, a predetermined amount of the compound (a2) having an isocyanate group is added to the mixture of the component (a1) and the component (a3) over a predetermined time and reacted.
In addition, (A) an oligomer having two or more ethylenically unsaturated bonds in the molecule can be prepared by a conventionally known method using the above-described components, for example, a polymerization inhibitor such as p-methoxyphenol and dibutyltin dilaurate. It can be produced by a method in which the above-described components are reacted in the presence of a catalyst.

(Physical properties of component (A))
In the present invention, (A) the weight average molecular weight of the oligomer having two or more ethylenically unsaturated bonds in the molecule is 1,000 to 40,000 from the viewpoints of curability, flexibility, and workability. It is preferably 3,000 to 30,000, more preferably 5,000 to 25,000, and even more preferably 5,000 to 20,000.

In the present specification, the number average molecular weight of the component (A) is measured by gel permeation chromatography (GPC), and is converted to a standard polystyrene calibration curve. The number average molecular weight, weight average molecular weight, and degree of dispersion are defined as follows when Ni molecules having a molecular weight Mi exist in the component (A).
(A) Number average molecular weight (Mn)
Mn = Σ (N _i M _i ) / ΣNi = ΣX _i M _i
(X _i = Mole fraction of molecules with molecular weight M _i = N _i / ΣN _i )
(B) Weight average molecular weight (Mw)
Mw = Σ (N _i M _i ² ) / ΣN _i M _i = ΣW _i M _i
(W _i = weight fraction of molecules of molecular weight M _i = N _i M _i / ΣN _i M _i )
(C) Molecular weight distribution (dispersion degree)
Dispersity = Mw / Mn
In the present invention, the content of the oligomer (A) having two or more ethylenically unsaturated bonds in the molecule is the total amount of the component (A) and the component (B) from the viewpoints of curability, adhesion and cure shrinkage. The amount is preferably 25 to 90 parts by mass, more preferably 30 to 80 parts by mass, and particularly preferably 40 to 70 parts by mass with respect to 100 parts by mass.

<(B) component: Plasticizer>
As the plasticizer (B) in the present invention, for example, a polyester plasticizer of a dibasic acid and a polyhydric alcohol; the molecular chain is composed of an alkyl acrylate monomer unit and / or an alkyl methacrylate monomer unit. And liquid acrylic resin plasticizers such as polyether plasticizers such as polypropylene glycol and derivatives thereof; urethane plasticizers (urethane oligomers); and polystyrene plasticizers such as poly-α-methylstyrene and polystyrene.
In addition, the (B) plasticizer in this invention means the oligomer which does not have an ethylenically unsaturated bond in a molecule | numerator, or has one.

Specifically, PPG 3000 (trade name: Actol P-23; polyether polyol having a molecular weight of about 3000 manufactured by Mitsui Takeda Chemical Co., Ltd.), Exenol 5030 (number average molecular weight manufactured by Asahi Glass Co., Ltd. is about 5100) Polyether polyol), Exenol 823 (a polyether triol having a number average molecular weight of about 5000, manufactured by Asahi Glass Co., Ltd.), an oxypropylene polymer having Mn = 5200 and Mw / Mn = 1.6 at both ends having an allyl ether group ARUFON UP series (trade name, manufactured by Toa Gosei Co., Ltd.), which is an acrylic resin plasticizer.

The weight average molecular weight of the (B) plasticizer used in the present invention is preferably 1,000 to 20,000, more preferably 2,000 to 15,000, from the viewpoint of suppressing bleeding out. More preferably, it is 3,000 to 10,000, and even more preferably 6,000 to 8,000.
The (B) plasticizer used in the present invention is obtained by reacting a plasticizer having a polyether skeleton such as polyether polyol, or a polyalkylene glycol and diisocyanate, from the viewpoint of further improving the curability of the light shielding part. Urethane plasticizers are preferred, but urethane plasticizers are more preferred.
Furthermore, the plasticizer of the present invention is preferably an oligomer having substantially no ethylenically unsaturated bond in the molecule. “Substantially” means that the average value of the number of ethylenically unsaturated bonds per molecule in the whole component (B) is 0.1 or less. That is, the mixing ratio of the oligomer having one ethylenically unsaturated bond in the molecule and the oligomer having no ethylenically unsaturated bond in the molecule is preferably 1/10 or less. The average value of the number of ethylenically unsaturated bonds per molecule can be calculated from the integrated value of ¹ H-NMR.

The urethane-based plasticizer can be obtained, for example, by reacting (a1) a diol compound with (a2) a compound having an isocyanate group and blocking the end with a monoalcohol such as butanol as necessary.
(A1) The diol compound is preferably a polyalkylene glycol such as polypropylene glycol, polyethylene glycol, polytetramethylene ether glycol, and more preferably polypropylene glycol.
(A2) Examples of the compound having an isocyanate group include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, naphthalene diisocyanate, and the like, preferably hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, Trimethylhexamethylene diisocyanate is more preferred.

The content of the (B) plasticizer used in the present invention is 10 to 75 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B) from the viewpoints of curability, adhesion and cure shrinkage. Is more preferable, 20 to 70 parts by mass is more preferable, and 30 to 60 parts by mass is particularly preferable.

<(C) component: photopolymerization initiator>
Examples of the photopolymerization initiator in the present invention include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy -4'-dimethylaminobenzophenone, α-hydroxyisobutylphenone, 2-ethylanthraquinone, t-butylanthraquinone, 1,4-dimethylanthraquinone, 1-chloroanthraquinone, 2,3-dichloroanthraquinone, 3-chloro-2-methyl Anthraquinone, 1,2-benzoanthraquinone, 2-phenylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy- Aromatic ketone compounds such as 2-diphenylethane-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin compounds such as benzoin, methylbenzoin and ethylbenzoin, benzoin methyl ether, benzoin Benzoin ether compounds such as ethyl ether, benzoin isobutyl ether, benzoin phenyl ether, ester compounds of β- (acridin-9-yl) acrylic acid, 9-phenylacridine, 9-pyridylacridine, 1,7-diacridinoheptane, etc. Acridine compound, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole dimer, 2- (o -Fluorophenyl) -4,5-diph Phenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2,4-di ( p-methoxyphenyl) 5-phenylimidazole dimer, 2- (2,4-dimethoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methylmercaptophenyl) -4,5-diphenylimidazole 2,4,5-triarylimidazole dimer such as dimer, benzyl, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) ) -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-1-propane, and the like.

In particular, those that do not color the resin composition include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) Α-hydroxyalkylphenone compounds such as -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2, Acylphosphine oxide compounds such as 6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, oligo (2-hydroxy-2-methyl) -1- (4- (1-methylvinyl) phenyl) propanone) and A combination thereof are preferred.
In order to produce particularly thick sheets, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine A photopolymerization initiator containing an acyl phosphine oxide compound such as oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide is preferable.
In order to reduce the odor of the sheet, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) is preferable. A plurality of these photopolymerization initiators may be used in combination.

The content of the (C) photopolymerization initiator used in the present invention is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the total amount of the component (A) and the component (B) from the viewpoint of curability. More preferably, it is 8 to 7 parts by mass, still more preferably 1 to 4 parts by mass, and still more preferably 1 to 2 parts by mass.

<(D) component: Thiol compound represented by general formula (1)>
The component (D) used in the present invention is not particularly limited as long as it is a compound represented by the general formula (1). However, from the viewpoint of the stability of the resin composition, m = 1 and R ¹ is A secondary thiol compound represented by the following general formula (3), which is a methyl group and R ² is a hydrogen atom, is preferred.

(In general formula (3), A represents an n-valent organic group, and n represents an integer of 1 to 6.)
Examples of such compounds include 1,4-bis (3-mercaptobutyryloxy) butane, 1,3,5-tris (3-mercaptobutyryloxyethyl) -1,3,5-triazine-2. 4,6 (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate), and the like. These compounds are available from Showa Denko KK as Karenz MT series (Karenz MT BD1, Karenz MT NR1, Karenz MT PE1, etc.). These compounds can be used individually by 1 type or in combination of 2 or more types.
The content of the thiol compound represented by the general formula (1), which is the component (D) used in the present invention, is the total amount of the component (A) and the component (B) from the viewpoint of curability of the light shielding part and wet heat resistance. The amount is preferably 3 to 30 parts by mass, more preferably 8 to 25 parts by mass, and particularly preferably 10 to 20 parts by mass with respect to 100 parts by mass.

A stabilizer etc. can be arbitrarily added to the photocurable resin composition by this invention as needed. The stabilizer is added for the purpose of improving the stability of the photocurable resin composition, and examples thereof include triphenyl phosphite.
Moreover, in this invention, it is preferable that an organic solvent (solvent) is not included substantially from a viewpoint of heat-and-moisture resistance reliability and suppressing the bubble generation in hardened | cured material.
“Substantially” means that the photo-curing resin composition of the present invention is not significantly deteriorated after photo-curing, and the organic solvent is present in a small amount (1% by mass or less) in the photo-curing resin composition. It means that it may be, but preferably it is not contained. Here, the organic solvent is an organic compound that does not have an ethylenically unsaturated group in the molecule, is liquid at 25 ° C., and has a boiling point of 250 ° C. or less at atmospheric pressure.

The viscosity (25 ° C.) of the photocurable resin composition of the present invention is preferably 500 to 5000 mPa · s, and preferably 1,000 to 5,000 mPa · s from the viewpoint of bleeding out and workability. More preferably, it is 2,000 to 4,000 mPa · s.

<Image display device>
Hereinafter, a liquid crystal display device which is an example of an image display device that can be manufactured by using the photocurable resin composition of the present embodiment will be described.
FIG. 1 is a side sectional view schematically showing an embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 1 includes an image display unit 1 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 10, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. The transparent resin layer 32 provided on the upper surface of 20 and the transparent protective substrate (protective panel) 40 provided on the surface thereof. The transparent resin layer 32 is composed of a cured body of the photocurable resin composition of the present embodiment.
FIG. 2 is a side cross-sectional view schematically showing a liquid crystal display device equipped with a touch panel, which is an embodiment of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 2 includes an image display unit 1 in which a backlight system 50, a polarizing plate 22, a liquid crystal display cell 10, and a polarizing plate 20 are laminated in this order, and a polarizing plate on the viewing side of the liquid crystal display device. 20, a transparent resin layer 32 provided on the top surface, a touch panel 30 provided on the top surface of the transparent resin layer 32, a transparent resin layer 31 provided on the top surface of the touch panel 30, and a transparent protective substrate provided on the surface thereof 40.
In the liquid crystal display device of FIG. 2, a transparent resin layer is interposed between the image display unit 1 and the touch panel 30 and between the touch panel 30 and the transparent protective substrate 40. It suffices to be interposed in at least one of these. When the touch panel is on-cell, the touch panel and the liquid crystal display cell are integrated. As a specific example, the liquid crystal display cell 10 of the liquid crystal display device of FIG. 1 may be replaced with an on-cell.
According to the liquid crystal display device shown in FIGS. 1 and 2, since the cured body of the photocurable resin composition of the present embodiment is provided as the transparent resin layer 31 or 32, it has impact resistance and is not sharp and has no double image. A high contrast image can be obtained.

The liquid crystal display cell 10 can be made of a liquid crystal material well known in the art. Further, according to the control method of the liquid crystal material, it is classified into a TN (Twisted Nematic) method, an STN (Super-twisted nematic) method, a VA (Virtual Alignment) method, an IPS (In-Place-Switching) method, etc. Then, it may be a liquid crystal display cell using any control method.
As the polarizing plates 20 and 22, a polarizing plate common in this technical field can be used. The surfaces of these polarizing plates may be subjected to treatments such as antireflection, antifouling, and hard coat. Such surface treatment may be performed on one side of the polarizing plate or on both sides thereof.
As the touch panel 30, what is generally used in this technical field can be used.
The transparent resin layer 31 or 32 can be formed with a thickness of 0.02 mm to 3 mm, for example. In particular, the photocurable resin composition of the present embodiment is effective for thick films, and can be suitably used when the transparent resin layer 31 or 32 of 0.1 mm or more is formed.
As the transparent protective substrate 40, a general optical transparent substrate can be used. Specific examples thereof include inorganic plates such as glass plates and quartz plates, resin plates such as acrylic plates and polycarbonate plates, and resin sheets such as thick polyester sheets. When high surface hardness is required, a plate such as glass or acrylic is preferable, and a glass plate is more preferable. The surface of these transparent protective substrates may be subjected to treatments such as antireflection, antifouling, and hard coating. Such surface treatment may be performed on one side of the transparent protective substrate or on both sides. A plurality of transparent protective substrates can be used in combination.
The backlight system 50 typically includes a reflecting unit such as a reflecting plate and an illuminating unit such as a lamp.

The liquid crystal display device of FIG. 1 described above includes the step of interposing the photocurable resin composition of the present embodiment between the image display unit and the protective panel, and the photocuring by irradiating light from the protective panel surface side. And a step of curing the conductive resin composition to form a transparent resin layer.
As a method of interposing the photocurable resin composition between the image display unit and the protective panel, for example, using a dispenser, the photocurable resin composition is applied on the image display unit or the protective panel, and then vacuum ( And a method of casting a photocurable resin composition between an image display unit and a protective panel arranged at a certain interval. In addition, when casting a photocurable resin composition, you may form a dam around an image display unit and a protection panel.
The liquid crystal display device of FIG. 2 described above includes a step of interposing the photocurable resin composition of the present embodiment between the image display unit and the touch panel and / or between the touch panel and the protective panel. And a step of curing the photocurable resin composition by irradiating light from the protective panel surface side to form a transparent resin layer. Examples of the method for interposing the photocurable resin composition include the same method as in the case of the liquid crystal display device shown in FIG.

The light irradiation, for example, using an ultraviolet irradiation device can be carried out under the conditions of exposure ^{500mJ / cm 2 ~ 5000mJ / cm} 2. The exposure amount refers to a value obtained by multiplying the illuminance that can be measured with an ultraviolet illuminance meter UV-M02 (receiver: UV-36) manufactured by Oak Co., Ltd., by the irradiation time (seconds). The light source for ultraviolet irradiation may be a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, an LED lamp or the like, but it is preferable to use a high pressure mercury lamp or a metal halide lamp.
In the case of light irradiation, irradiation from the protective panel surface side and irradiation from the side surface may be used in combination. Moreover, hardening can also be accelerated | stimulated by heating the laminated body containing a photocurable resin composition simultaneously with light irradiation.

The liquid crystal display device that can be manufactured by using the photocurable resin composition of the present embodiment has been described above. However, it can be manufactured by using the photocurable resin composition of the present embodiment. The image display device is not limited to this, and can be applied to a plasma display (PDP), a cathode ray tube (CRT), a field emission display (FED), an organic EL display, a 3D display, electronic paper, and the like.

In the method for producing an image display device of the present invention, an image display unit having an image display unit and a protective panel are arranged to face each other, and the photocurable resin composition is interposed between them. The present invention is particularly preferably applied to a method for producing an image display device for curing a conductive resin composition. In the method for manufacturing an image display device of the present invention, the protective panel has a light shielding portion formed along an outer peripheral edge, and at least protects the photocurable resin composition between the image display unit and the protective panel. It has the process of performing light irradiation from the panel surface side.
When a light shielding part is provided on the protective panel, sufficient light does not reach the photocurable resin composition filled between the image display unit and the protective panel, hindering curing, and photocuring properties around the light shielding part. Curing of the resin composition does not proceed sufficiently, greatly degrading the quality of the image display device and causing a decrease in reliability.
Therefore, in the present invention, light is irradiated from the protective panel surface side, and curing is performed in combination with the photocurable resin composition containing the components (A) to (D). In order to irradiate light from the protective panel surface side, an ultraviolet irradiation device is used, and the photocurable resin composition filled between the image display unit and the protective panel is almost perpendicular to the photocurable resin composition layer. Irradiate ultraviolet rays from the protective panel surface side. At the same time, the photocurable resin composition layer may be irradiated with light from a substantially parallel direction. For example, using an ultraviolet irradiation device connected to an optical fiber or the like, the photocurable resin composition filled between the image display unit and the protective panel is placed outward so as to be substantially parallel to the photocurable resin composition layer. Irradiate ultraviolet rays from the side.
The photocurable resin composition of the present invention is a composition that cures the vicinity of the light-shielding portion when light irradiation is performed from the protective panel surface side.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.
First, production examples of a photocurable resin composition that can be used in an image display device to which the present invention is applied will be described below.
In the following synthesis examples, the weight average molecular weight was measured using gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent, and polystyrene was determined as a standard substance. The GPC conditions are shown below.
(GPC conditions)
Measuring instrument: HLC-8320GPC [Tosoh Corporation]
Analytical column: TSKgel SuperMultipore HZ-H (consolidated 3) [Tosoh Corporation]
Guard column: TSK guard column SuperMP (HZ) -H [Tosoh Corporation]
Eluent: THF
Measurement temperature: 25 ° C

Synthesis Example 1 (Synthesis of polyurethane acrylate oligomer)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 155 parts by mass of polypropylene glycol (molecular weight 2,000), 17.9 parts by mass of 2-hydroxyethyl acrylate, p-as a polymerization inhibitor Take 0.5 parts by weight of methoxyphenol and 0.05 parts by weight of dibutyltin dilaurate as a catalyst, raise the temperature to 70 ° C. while flowing air, and then 32.4 parts by weight of trimethylhexamethylene diisocyanate while stirring at 70 to 75 ° C. The portion was added dropwise over 2 hours to carry out the reaction.
When the reaction was completed for 5 hours after completion of the dropwise addition, the reaction was terminated by confirming that the isocyanate had disappeared as a result of IR measurement, and had polypropylene glycol and trimethylhexamethylene diisocyanate as repeating units, with ethylene at both ends. The polyurethane acrylate oligomer (weight average molecular weight 7,000) which has an ionic unsaturated bond was obtained.

Synthesis Example 2 (Synthesis of polyurethane acrylate oligomer)
In a reaction vessel equipped with a cooling tube, a thermometer, a stirrer, a dropping funnel and an air injection tube, 180 parts by mass of polypropylene glycol (molecular weight 2,000), 2.33 parts by mass of 2-hydroxyethyl acrylate, p-as a polymerization inhibitor Take 0.5 parts by weight of methoxyphenol and 0.05 parts by weight of dibutyltin dilaurate as a catalyst, raise the temperature to 70 ° C. while flowing air, and then 22.2 parts by weight of trimethylhexamethylene diisocyanate while stirring at 70 to 75 ° C. The portion was added dropwise over 2 hours to carry out the reaction.
When the reaction was completed for 5 hours after completion of the dropwise addition, the reaction was terminated by confirming that the isocyanate had disappeared as a result of IR measurement, and had polypropylene glycol and trimethylhexamethylene diisocyanate as repeating units, with ethylene at both ends. The polyurethane acrylate oligomer (weight average molecular weight 20,000) which has an ionic unsaturated bond was obtained.

Synthesis Example 3 (Synthesis of polyurethane acrylate oligomer)
In a reaction vessel equipped with a condenser, a thermometer, a stirrer, a dropping funnel and an air injection tube, 157 parts by mass of polypropylene glycol (molecular weight 2,000), 9.1 parts by mass of 2-hydroxyethyl acrylate, 1.81-butanol 5.81 Part by mass, 0.5 part by mass of p-methoxyphenol as a polymerization inhibitor and 0.05 part by mass of dibutyltin dilaurate as a catalyst, the temperature was raised to 70 ° C. while flowing air, and then trimethyl with stirring at 70 to 75 ° C. 33 parts by mass of hexamethylene diisocyanate was uniformly added dropwise over 2 hours to carry out the reaction.
When the reaction was completed for 5 hours after completion of the dropping, the reaction was terminated by confirming that the isocyanate had disappeared as a result of IR measurement, and had polypropylene glycol and trimethylhexamethylene diisocyanate as repeating units, A polyurethane acrylate oligomer having an ethylenically unsaturated bond (weight average molecular weight 7,000) was obtained.

Synthesis Example 4 (Synthesis of urethane oligomer)
In a reaction vessel equipped with a cooling tube, thermometer, stirring device, dropping funnel and air injection tube, 160 parts by weight of polypropylene glycol (molecular weight 2,000), 11.8 parts by weight of 1-butanol, and p-methoxyphenol as a polymerization inhibitor 0.5 parts by mass and 0.05 parts by mass of dibutyltin dilaurate as a catalyst were heated to 70 ° C. while flowing air, and then 33.48 parts by mass of trimethylhexamethylene diisocyanate was stirred at 70 to 75 ° C. The reaction was performed dropwise over 2 hours so as to be uniform.
When the reaction was completed for 5 hours after completion of the dropwise addition, the reaction was terminated after confirming that the isocyanate had disappeared as a result of IR measurement, and a polyurethane having a repeating unit of polypropylene glycol and trimethylhexamethylene diisocyanate (weight average molecular weight 7 , 000).

Example 1
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1 containing the component (A) as a main component, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer for the component (B), and diphenyl- ( 2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (product name: SPEDDCURE TPO) manufactured by LAMBSON, 1.2 parts by mass, component (D) pentaerythritol tetrakis (3-mercapto) having the following structure 17.9 parts by weight of butyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK) was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 2
29.8 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 70.2 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization started) Agent) (LAMBSON, trade name SPEDDCURE TPO) 1.2 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (Showa Denko K.K., trade name Karenz MT PE1) 17.9 A mass part was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 3
89.3 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 10.7 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization started) Agent) (LAMBSON, trade name SPEDDCURE TPO) 1.2 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (Showa Denko K.K., trade name Karenz MT PE1) 17.9 A mass part was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 4
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (LAMBSON) 1.2 parts by mass, trade name SPEDCURE TPO), 1,4-bis (3-mercaptobutyryloxy) butane (secondary thiol) (made by Showa Denko KK, trade name Karenz MT BD1) having the following structure ) 17.9 parts by mass were weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 5
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (LAMBSON) 1.2 parts by mass, trade name: SPEDDCURE TPO), 1,3,5-tris (3-mercaptobutyryloxyethyl) -1,3,5-triazine-2,4,6 (1H) , 3H, 5H) -trione (secondary thiol) (product name Karenz MT NR1, manufactured by Showa Denko KK) was weighed and mixed with stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 6
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (LAMBSON) 1.2 parts by mass, trade name SPEDDCURE TPO), 17.9 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK) 0.6 parts by mass of triphenyl phosphate was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 7
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, 1-hydroxy-cyclohexyl-phenyl-ketone (photopolymerization initiator) (manufactured by BASF, trade name Irgacure 184) 1.2 parts by mass, 17.9 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK), and stirred and mixed. A photocurable resin composition was prepared. The evaluation results of this resin composition are shown in Table 1.

Example 8
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, 2- (dimethylamino) -1- (4-morpholinophenyl) -2-benzyl-1-butanone (Photopolymerization initiator) (BASF, trade name Irgacure 369) 1.2 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (Showa Denko K.K., trade name Karenz MT PE1 ) 17.9 parts by weight were weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 9
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 2, 50 parts by mass of the polyurethane obtained in Synthesis Example 4 as a plasticizer, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (LAMBSON) 1.79 parts by mass of trade name, SPEDCURE TPO), and pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK) were weighed. Then, the mixture was stirred and mixed to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 10
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of a non-functional acrylic polymer (manufactured by Toa Gosei Co., Ltd., trade name ARUFON UP-1000, weight average molecular weight: 3,000) as a plasticizer, diphenyl- ( 2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by LAMBSON, trade name SPEEDCURE TPO) (photopolymerization initiator) 1.2 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) ( 17.9 parts by mass of Showa Denko K.K., trade name Karenz MT PE1) was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 11
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of polyether triol (manufactured by Asahi Glass Co., Ltd., trade name Exenol 823, number average molecular weight; 5,000) as a plasticizer, diphenyl- (2,4 6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (produced by LAMBSON, trade name SPEDDCURE TPO) 1.2 parts by mass, pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (Showa Denko K.K. ), Trade name Karenz MT PE1) 17.9 parts by mass were weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Example 12
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 3, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (manufactured by LAMBSON) 1.2 parts by mass of trade name SPEDCURE TPO), 17.9 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK), and stirred. By mixing, a photocurable resin composition was prepared. The evaluation results of this resin composition are shown in Table 3.

Comparative Example 1
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (manufactured by LAMBSON, 1.2 parts by mass of trade name SPEDCURE TPO) was weighed and mixed by stirring to prepare a photocurable resin composition. The evaluation results of this resin composition are shown in Table 1.

Comparative Example 2
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 50 parts by mass of the polyurethane obtained in Synthesis Example 4, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (manufactured by LAMBSON, 1.2 parts by mass of trade name SPEDCURE TPO) and 17.9 parts by mass of 2-mercaptobenzimidazole (primary thiol) (trade name Antage MB, manufactured by Kawaguchi Chemical Industry Co., Ltd.) having the following structure are weighed and mixed. Then, a photocurable resin composition was prepared. The evaluation results of this resin composition are shown in Table 1.

Comparative Example 3
50 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 3, 50 parts by mass of the polyurethane obtained in Synthesis Example 4, diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (photopolymerization initiator) (manufactured by LAMBSON) 1.2 parts by mass of trade name SPEDCURE TPO), 17.9 parts by mass of pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko KK), and stirred. By mixing, a photocurable resin composition was prepared. The evaluation results of this resin composition are shown in Table 1.

Comparative Example 4
100 parts by mass of the polyurethane acrylate oligomer obtained in Synthesis Example 1, 1.2 parts by mass of diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide (manufactured by LAMBSON, trade name SPEDCURE TPO) (photopolymerization initiator), 17.9 parts by weight of pentaerythritol tetrakis (3-mercaptobutyrate) (secondary thiol) (trade name Karenz MT PE1, manufactured by Showa Denko K.K.) was weighed and mixed with stirring to obtain a photocurable resin composition. Prepared. The evaluation results of this resin composition are shown in Table 1.

A test method for each resin composition obtained in each example and each comparative example and a transparent sheet obtained by curing the resin composition is shown below.
(viscosity)
The viscosity of each resin composition obtained in each example and each comparative example was measured by an E-type viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) using a 3 ° cone rotor at 0.5 rpm at 25 ° C. The viscosity was measured.
(Viscosity stability)
The viscosity at 25 ° C. of the resin composition was measured using an E-type viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). The resin composition to be used for viscosity measurement was sealed in a light-shielding polypropylene container, and then stored for 30 days in a sealed state maintained at 25 ° C. And the viscosity of 25 degreeC was measured with the E-type viscosity meter after progress for a predetermined period, and the change rate of the viscosity after 25 degreeC / 30 day passage when the viscosity before sealing was set to 100 based on the measured value was computed. At this time, when the rate of change is 10% or less, the viscosity stability is high and good “G (Good)”, and when the rate of change exceeds 10%, the viscosity stability is low and bad “P (Poor)”. did.

(Curable)
A resin composition is dropped onto a glass substrate (100 × 100 mm), and a PET film (Toyobo Co., Ltd. A4100, 100 mm × 100 mm × 100 μm) is bonded through a 175 μm spacer so that the film thickness becomes 175 μm. Ultraviolet rays were irradiated from the side using an ultraviolet irradiation device at a rate of 2,000 mJ / cm ² to produce a transparent sheet. At this time, a light shielding part having a width of 30 mm was formed on the outer periphery of the PET film on the ultraviolet irradiation side. The curability of the obtained cured product was evaluated by a finger from the PET film side of the obtained three-layer laminate (glass substrate / transparent sheet / PET film). The film that could not be formed was evaluated as “uncured”. For the light-shielding portion, the width where the curability was “cured” was evaluated with calipers. The larger the curing width, the better the characteristics.

(Moisture and heat resistance reliability)
The prepared resin composition is dropped onto a 2 inch square glass substrate, and another 2 inch square glass substrate is bonded through a 175 μm spacer so as to have a film thickness of 175 μm, and from one glass substrate side. A test piece was obtained by irradiating ultraviolet rays at 2,000 mJ / cm ² using an ultraviolet irradiation device. At this time, a light shielding part having a width of 10 mm was formed on the outer periphery of the glass substrate on the ultraviolet irradiation side. This three-layer laminate (glass substrate / transparent sheet / glass substrate) was placed in a test bath at 85 ° C. and 85% RH for 50 hours, and the presence or absence of peeling, liquid dripping, or generation of bubbles of 50 μm or more was visually evaluated.

(optical properties)
A resin composition is dropped onto a PET film (Toyobo Co., Ltd. A4100, 86 mm × 56 mm × 100 μm), and another similar PET film is bonded through a 175 μm spacer so that the film thickness becomes 175 μm. A transparent sheet in which the resin composition was cured by irradiating ultraviolet rays at 2,000 mJ / cm ² from one PET film side using an irradiation apparatus was produced. Using the two-layer PET as a baseline for transmittance, the transparent sheet was peeled off from the obtained three-layer laminate (PET film / transparent sheet / PET film), and the transmittance of this transparent sheet was measured with a spectrophotometer (Corporation). It was measured using Shimadzu UV-2400PC). Further, the haze of the transparent sheet was measured using a haze meter (Suga Test Instruments Co., Ltd. HGM-2). The transmittance is evaluated when the transmittance is 400 nm. When the transmittance is 98% or more, the transmittance is high and good “G”, and when the transmittance is less than 98%, the transmittance is low and inferior “P”. " When the haze was less than 1%, the turbidity was low and good “G”, and when the haze was 1% or more, the turbidity was high and inferior “P”.

(Curing shrinkage)
A resin composition is dropped onto a PET film (Toyobo Co., Ltd. A4100, 86 mm × 56 mm × 100 μm), and another similar PET film is bonded through a 175 μm spacer so that the film thickness becomes 175 μm. A transparent sheet in which the resin composition was cured by irradiating ultraviolet rays at 2,000 mJ / cm ² from one PET film side using an irradiation apparatus was produced. The transparent sheet was peeled off from the obtained three-layer laminate (PET film / transparent sheet / PET film), and the specific gravity of the transparent sheet and the resin composition before curing was measured with an electronic hydrometer (Alpha Mirage SD- 200L), and the cure shrinkage was calculated from the following equation.
Curing shrinkage rate (%) = {(specific gravity of the resin composition after curing−specific gravity of the resin composition before curing) / specific gravity of the resin composition before curing} × 100

(Adhesive force)
A resin composition is dropped onto a glass substrate, and a PET film (Toyobo Co., Ltd. A4100, 110 mm × 200 mm × 100 μm) is bonded through a 175 μm spacer so as to have a film thickness of 175 μm. A transparent sheet in which the resin composition was cured by irradiating ultraviolet rays at 2,000 mJ / cm ² from the PET film side was prepared. The obtained three-layer laminate (glass substrate / transparent sheet / PET film) was cut to a width of 25 mm. The adhesive strength was measured using an autograph (Shimadzu Corporation, AGS-1000G) at a peeling angle of 180 °, a peeling speed of 300 mm / min, and a temperature of 25 ° C. In this case, when the adhesive strength is 0.8 N / 25 mm or more, the adhesive strength is “E (Excellent)” which is very good and the adhesive strength is less than 0.8 N / 25 mm and 0.5 N / 25 mm or more. Was evaluated as “P (Poor)” where the adhesive strength was low and inferior when the adhesive strength was less than 0.5 N / 25 mm.

(Growth rate)
A resin composition is dropped onto a PET film (Toyobo Co., Ltd. A4100, 80 mm × 40 mm × 100 μm), and another similar PET film is bonded through a 540 μm spacer so as to have a film thickness of 540 μm. A transparent sheet in which the resin composition was cured by irradiating ultraviolet rays at 2,000 mJ / cm ² from one PET film side using an irradiation apparatus was produced. The transparent sheet was peeled off from the obtained three-layer laminate (PET film / transparent sheet / PET film), and the transparent sheet was cut into a width of 10 mm. The elongation was measured using an autograph (Shimadzu Corporation AGS-1000G) at a speed of 500 mm / min and a temperature of 25 ° C. At this time, the case where the elongation was 300% or higher was evaluated as “G”, which is high and good, and the case where the elongation was below 300% was evaluated as “P”, which is low and inferior.
(Reworkability)
A resin composition is dropped on a glass substrate, and two PET films (Toyobo Co., Ltd. A4100, 100 μm) are bonded through a 175 μm spacer, and ultraviolet rays are applied from one PET film side using an ultraviolet irradiation device. A transparent sheet in which the resin composition was cured by irradiation with 1,000 mJ / cm ² was produced. The PET film was peeled off from the obtained three-layer laminate (glass substrate / transparent sheet / PET film), and the transparent sheet was then removed at 23 ° C. and 65% R.D. H. It was judged whether the transparent sheet can be easily peeled off by peeling from the glass by hand under the above conditions. At this time, if the transparent sheet can be easily peeled off and the glass has no residue, it is “E”. If the transparent sheet is peelable and the glass has no residue, it is “G”, and the residue remains on the glass. The case was evaluated as “P”.
The test results of each example and comparative example are summarized in Tables 1 to 4.

From Table 1, the comparative example 1 which does not mix | blend the thiol compound represented by General formula (1) does not have curability of a light-shielding part, and since hardening does not advance, it will dripping. Also, Comparative Example 2 using a thiol compound that is not a thiol compound represented by the general formula (1) is similar to Comparative Example 1 in which no thiol compound is blended. Also inferior. In addition, Comparative Example 3 using an oligomer having one ethylenically unsaturated bond at the end, not using an oligomer having two or more ethylenically unsaturated bonds in the molecule of the component (A), The light shielding part was not cured, and dripping occurred. And the comparative example 4 which does not use the plasticizer of (B) component produced | generated the bubble in the light-shielding part in the case of hardening, and also the cure shrinkage rate was large and it was a thing with poor adhesiveness.
In contrast to these comparative examples, it can be seen that when the resin compositions according to the present invention (Examples 1 to 12) are used, curing proceeds sufficiently even when filled between substrates having light-shielding portions. Moreover, it confirmed that it was excellent also in the viscosity stability of the hardened | cured material obtained at this time, a heat-and-moisture-resistant reliability test, an optical characteristic, a cure shrinkage rate, adhesiveness, elongation rate, and rework property.

DESCRIPTION OF SYMBOLS 1 Image display unit 10 Liquid crystal display cell 20 Polarizing plate 22 Polarizing plate 30 Touch panel 31 Transparent resin layer 32 Transparent resin layer 40 Transparent protective substrate 50 Backlight system

Claims (8)

1. (A) an oligomer having two or more ethylenically unsaturated bonds in the molecule;
   (B) a plasticizer,
   (C) a photopolymerization initiator, and (D) a thiol compound represented by the following general formula (1),
   A photocurable resin composition comprising:
   

   

   (In the general formula (1), R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m represents an integer of 0 to 3, and n represents an integer of 1 to 6) A represents an n-valent organic group.)
2. The photocurable resin composition according to claim 1, wherein the component (A) is a urethane oligomer having two or more (meth) acryloyl groups.
3. The photocurable resin composition according to claim 1 or 2, wherein the component (B) is a urethane oligomer having no or one ethylenically unsaturated bond in the molecule.
4. The photocurable resin composition according to any one of claims 1 to 3, which contains substantially no organic solvent and has a viscosity at 25 ° C of 500 to 5000 mPa · s.
5. The photocuring property according to any one of claims 1 to 4, wherein the content of the component (B) is 10 to 75 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). Resin composition.
6. The photocurability according to any one of claims 1 to 5, wherein the content of the component (D) is 3 to 30 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). Resin composition.
7. An image display unit having an image display unit and a protective panel are arranged to face each other, and the photocurable resin composition according to any one of claims 1 to 6 is interposed between the image display unit and the protective panel. A method for manufacturing an image display device for curing an object, wherein the protective panel has a light-shielding portion along an outer peripheral edge, and the photocurable resin composition between the image display unit and the protective panel A method of manufacturing an image display device that performs light irradiation at least from the protective panel side.
8. An image display device manufactured by the manufacturing method according to claim 7.

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