JP6689051B2 - Photocurable resin composition and method for manufacturing image display device - Google Patents

Description

  The present invention, an image display member and a light-transmissive optical member disposed on the surface side thereof are bonded and laminated via a light-transmissive cured resin layer, and used when manufacturing an image display device. The present invention relates to a photocurable resin composition for forming a transparent cured resin layer and a method for manufacturing an image display device.

  An image display device such as a liquid crystal display panel used for an information terminal such as a smart phone has a photocurable resin composition between an image display member such as a liquid crystal display panel or an organic EL panel and a light transmissive optical member. Then, a photocurable resin composition layer is formed. Then, the photocurable resin composition layer is irradiated with light to be cured to form a light transmissive cured resin layer. Thus, the image display device is manufactured by bonding and laminating the image display member and the light transmissive optical member.

  As the photocurable resin composition, for example, a photocurable resin composition containing a (meth) acrylate oligomer component, an alkyl (meth) acrylate monomer component, a photopolymerization initiator, and a plasticizer component is proposed. (See, for example, Patent Documents 1 and 2).

JP, 2014-237745, A International Publication No. 2013/013568

  In order to obtain more sufficient adhesive strength, it may be desired to design the glass transition temperature of the light-transmitting cured resin layer (cured product of the light-curable resin composition) to be higher than the use temperature.

  Here, the higher the elastic modulus of the light-transmissive cured resin layer in the low temperature environment, the lower the light-transmissive cured resin layer and the adherend (such as the light-transmissive optical member or image It has been found that it tends to peel off from the display member). It has been found that such a tendency is remarkable particularly when the glass transition temperature of the curable resin composition layer is high. Therefore, there is a demand for a photocurable resin composition that can reduce the elastic modulus of the light transmissive cured resin layer under a low temperature environment.

  The present invention has been proposed in view of such conventional circumstances, and provides a photocurable resin composition capable of reducing the elastic modulus of a light transmissive cured resin layer in a low temperature environment.

  The photocurable resin composition according to the present invention contains a (meth) acrylic oligomer having a urethane skeleton, a (meth) acrylate monomer, a polymerization initiator, and a plasticizer. It contains at least one of polybutadiene having a binding rate of less than 80% and polyisoprene having a 1,2 binding rate of less than 80%.

  Further, the method for manufacturing an image display device according to the present invention includes a step of applying a photocurable resin composition to the surface of a light transmissive optical member or the surface of an image display member, the image display member and the light transmissive optical member. And a step of laminating the photocurable resin composition via the photocurable resin composition, and a step of curing the photocurable resin composition, and the photocurable resin composition is the above-described photocurable resin composition.

  The present invention relates to a (meth) acrylic oligomer having a urethane skeleton, a (meth) acrylic monomer, polybutadiene having a 1,2 bond ratio of less than 80%, and polybutadiene having a 1,2 bond ratio of less than 80%. By using the photocurable resin composition containing at least one type of isoprene, the elastic modulus of the light transmissive cured resin layer in a low temperature environment can be lowered.

FIG. 1A is an explanatory diagram showing an example of a step (A1) of a method for manufacturing an image display device. FIG. 1B is an explanatory diagram showing an example of a step (B1) of the method for manufacturing the image display device. FIG. 1C is an explanatory diagram showing an example of a step (C1) of the method for manufacturing the image display device. FIG. 1D is an explanatory diagram illustrating an example of a step (C1) of the method for manufacturing the image display device. FIG. 2A is an explanatory diagram showing an example of the step (A2) of the method for manufacturing an image display device. FIG. 2B is an explanatory diagram showing an example of the step (A2) of the method for manufacturing the image display device. FIG. 2C is an explanatory diagram showing an example of a step (B2) of the method for manufacturing the image display device. FIG. 2D is an explanatory diagram illustrating an example of the step (B2) of the method for manufacturing the image display device. FIG. 2E is an explanatory diagram showing an example of the step (C2) of the method for manufacturing the image display device. FIG. 2F is an explanatory diagram showing an example of a step (D2) of the method for manufacturing the image display device. FIG. 2G is an explanatory diagram showing an example of a step (D2) of the method for manufacturing the image display device. FIG. 3A is an explanatory diagram showing an example of a step (A3) of the method for manufacturing the image display device. FIG. 3B is an explanatory diagram showing an example of the step (A3) of the method for manufacturing the image display device. FIG. 3C is an explanatory diagram showing an example of the step (B3) of the method for manufacturing the image display device. FIG. 3D is an explanatory diagram showing an example of a step (B3) of the method for manufacturing the image display device. FIG. 3E is an explanatory diagram showing an example of the step (C3) of the method for manufacturing the image display device. FIG. 4 is a perspective view showing a glass bonded body on which a light transmissive cured resin layer is formed. 5 is a cross-sectional view taken along the line A-A 'in FIG. FIG. 6 is a cross-sectional view for explaining an adhesive strength test of a glass joined body on which a light-transmitting cured resin layer is formed. FIG. 7: is a top view for demonstrating the adhesive strength test of the glass bonded body in which the light transmissive hardening resin layer was formed.

Hereinafter, embodiments of the present invention will be described in detail in the following order. In this specification, the term (meth) acrylate includes acrylate and methacrylate. Also, the term (meth) acryloyl includes acryloyl and methacryloyl.
1. Photocurable resin composition 2. 2. Method of manufacturing image display device Example

<1. Photocurable resin composition>
The photocurable resin composition according to the present embodiment includes a (meth) acrylic oligomer having a urethane skeleton (hereinafter, also referred to as urethane acrylate oligomer (A)), a (meth) acrylate monomer, and a polymerization initiator. , A plasticizer, and the plasticizer contains at least one of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80%. By using such a photocurable resin composition, the elastic modulus of the light transmissive cured resin layer in a low temperature environment can be lowered.

  The photocurable resin composition contains an acrylic oligomer and a (meth) acrylate monomer as radically polymerizable components, and a urethane acrylate oligomer (A) as an acrylic oligomer.

[Acrylic oligomer]
The acrylic oligomer is used as a reactive diluent for providing the photocurable resin composition with sufficient reactivity and coating property. The photocurable resin composition contains a urethane acrylate oligomer (A), and may contain an acrylic oligomer other than the urethane acrylate oligomer (A) as necessary.

[Urethane acrylate oligomer (A)]
The urethane acrylate oligomer (A) is an oligomer compound having a (meth) acryloyl group and a urethane bond.

  The urethane acrylate oligomer (A) has a weight average molecular weight of preferably 1,000 to 100,000, more preferably 1,000 to 70,000, and even more preferably 1,000 to 50,000.

  The urethane acrylate oligomer (A) is obtained, for example, by reacting a polyisocyanate compound, a (meth) acrylate having a hydroxyl group or an isocyanate group, and a polyol compound.

  Examples of the polyisocyanate compound include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, and diphenylmethane-4,4'-. Diisocyanates such as diisocyanate may be mentioned.

  Examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and polyethylene. Glycol (meth) acrylate is mentioned. Examples of the (meth) acrylate having an isocyanate group include methacryloyloxyethyl isocyanate.

  Examples of the polyol compound include alkylene type, polycarbonate type, polyester type or polyether type polyol compounds, and specifically, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polycarbonate diol, polyester diol, poly Examples include ether diol.

  Specific examples of the urethane acrylate oligomer (A) include, for example, TEAI-1000 (manufactured by Nippon Soda Co., Ltd.), EBECRYL230 (manufactured by Daicel Ornex Co., Ltd.), CN9014, CN9893, CN964, CN9001, CN9788, CN9783. (These are manufactured by Sartomer Co., Ltd.), UA-1 (manufactured by Light Chemical Industry Co., Ltd.) and the like can be used.

  The content of the urethane acrylate oligomer (A) in the photocurable resin composition is preferably 5 to 40% by mass, more preferably 20 to 40% by mass. The urethane acrylate oligomer (A) may be used alone or in combination of two or more. When two or more urethane acrylate oligomers (A) are used in combination, the total amount thereof preferably satisfies the above content range.

[Other (meth) acrylic oligomers]
Other (meth) acrylic oligomers include (meth) acrylate oligomers having skeletons such as polyisoprene and polybutadiene. Specific examples of the (meth) acrylate oligomer having a polyisoprene skeleton include esterified products of maleic anhydride adduct of polyisoprene polymer and 2-hydroxyethyl methacrylate (UC102, UC203, UC-1 (Kuraray Co., Ltd.). Company))).

  When the photocurable resin composition contains another (meth) acrylic oligomer, the content of the other (meth) acrylic oligomer in the photocurable resin composition may be 1 to 20% by mass. It is preferably 1 to 15% by mass. The other (meth) acrylic oligomers may be used alone or in combination of two or more. When two or more other (meth) acrylic oligomers are used in combination, the total amount thereof preferably satisfies the above content range.

[(Meth) acrylate monomer]
The (meth) acrylate monomer is not particularly limited, but it is preferable to contain a (meth) acrylate monomer having a ring structure from the viewpoint of more effectively lowering the elastic modulus of the light-transmitting cured resin layer in a low temperature environment. . Moreover, the (meth) acrylate monomer may further contain other (meth) acrylate monomers.

  The (meth) acrylate having a ring structure preferably has an alicyclic hydrocarbon group as the ring structure. 4-30 are preferable, as for carbon number of an alicyclic hydrocarbon group, 4-20 are more preferable, and 8-14 are more preferable. The alicyclic hydrocarbon group may have a monocyclic structure or a polycyclic structure. The alicyclic hydrocarbon group may be saturated or unsaturated. The alicyclic hydrocarbon group may have a substituent.

  The photocurable resin composition preferably contains a (meth) acrylate monomer represented by any of the following formulas (1) to (3) (hereinafter, also referred to as a specific (meth) acrylate monomer).

(In the formula (1) ~ (3), R independently represents a hydrogen atom or a methyl group, X is _{-O -, - O (CH 2} ) n O -, - O (CH 2 CH 2 O) _n -, or _{-O (CH (CH 3) CH} 2 O) n - , Y represents the _{-O -, - O (CH 2} ) m O -, - O (CH 2 CH 2 O) m -, or _{-O (CH (CH 3) CH} 2 O) m - represents a, n and m represents an integer of 1 to 10 independently).

  In formulas (1) to (3), it is preferable that each R independently represents a hydrogen atom. In formulas (1) to (3), it is preferable that each X independently represents -O-. In formula (3), Y preferably represents -O-. In formulas (1) to (3), it is preferable that n and m each independently represent an integer of 1 to 6.

  The specific (meth) acrylate monomer is preferably a (meth) acrylate monomer represented by the above formula (1) or formula (2). Specifically, the specific (meth) acrylate monomer is at least one of dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, and dicyclopentenyloxyethyl methacrylate. It is preferable. Particularly, at least one of dicyclopentanyl acrylate and dicyclopentanyl methacrylate is preferable.

  Specific examples of the (meth) acrylate monomer having a ring structure other than the specific (meth) acrylate monomer include isobornyl (meth) acrylate and the like.

  Moreover, hexanediol diacrylate etc. are mentioned as a specific example of (meth) acrylate other than the (meth) acrylate monomer which has the above-mentioned ring structure.

  The content of the (meth) acrylate monomer in the photocurable resin composition is preferably 15 to 45% by mass, more preferably 20 to 40% by mass. The (meth) acrylate monomers may be used alone or in combination of two or more. When two or more (meth) acrylate monomers are used in combination, the total amount thereof preferably satisfies the above content range.

  The content of the (meth) acrylate monomer having a ring structure in the photocurable resin composition is preferably 1 to 35% by weight, more preferably 10 to 35% by weight.

[Polymerization initiator]
As the polymerization initiator, it is preferable to use a photoradical polymerization initiator, and it is more preferable to contain at least one of an alkylphenone photopolymerization initiator and an acylphosphine oxide photopolymerization initiator, and an alkylphenone photopolymerization initiator is preferable. It is more preferable to contain a polymerization initiator and an acylphosphine oxide-based photopolymerization initiator. Examples of the alkylphenone-based photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (Irgacure 184, manufactured by BASF), 2-hydroxy-1- {4- [4- (21-hydroxy-2-methyl-propylonyl). Benzyl] phenyl} -2-methyl-1-propan-1-one (Irgacure 127, manufactured by BASF) can be used. As the acylphosphine oxide-based photopolymerization initiator, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO, manufactured by BASF) can be used. Examples of other polymerization initiators include benzophenone and acetophenone.

  The content of the photopolymerization initiator is preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 3 parts by mass, based on 100 parts by mass of the total of the radically polymerizable components. With such a range, insufficient curing can be prevented more effectively at the time of light irradiation, and increase in outgas due to cleavage can be prevented more effectively. The polymerization initiators may be used alone or in combination of two or more. When two or more polymerization initiators are used in combination, the total amount thereof preferably satisfies the above range.

[Plasticizer]
The photocurable resin composition contains, as a plasticizer, at least one of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80%. By containing such a plasticizer, the photocurable resin composition can reduce the elastic modulus of a cured product of the photocurable resin composition under a low temperature environment.

  In particular, the photocurable resin composition includes, as a plasticizer, a hydrogenated product of polybutadiene having a 1,2 bond rate of less than 80% and a hydrogenated product of polyisoprene having a 1,2 bond rate of less than 80%. It is preferable to contain at least one kind. Thereby, even when the glass transition temperature of the curable resin composition layer is high, the elastic modulus of the cured product of the photocurable resin composition in a low temperature environment can be effectively reduced. Also, the adhesive strength can be improved.

  The upper limit of the 1,2 bond ratio in the polybutadiene is preferably 75% or less, more preferably 70% or less. Further, the lower limit of the 1,2 bond ratio in the polybutadiene is preferably 50% or more, more preferably 55% or more, still more preferably 60% or more.

  Specific examples of the polybutadiene having a 1,2 bond ratio of less than 80% include Krasol HLBH-P2000 (hydrogenated polybutadiene having a 1,2 bond ratio of 65%, manufactured by Clay Valley), Krasol HLBH-P3000 ( Hydrogenated polybutadiene having a 1,2-bond ratio of 65%, manufactured by Clay Valley Co., Ltd., Krasol LBH-P2000 (polybutadiene having a 1,2-bond ratio of 65%, manufactured by Clay Valley, Krasol LBH-P3000 (1) , Polybutadiene having a 2-bond ratio of 65%, manufactured by Clay Valley Co., Ltd., LBH-P5000 (polybutadiene having a 1,2-bond ratio of 65% manufactured by Clay Valley Co., Ltd.), and the like.

  The upper limit of the 1,2 bond ratio in the polyisoprene is preferably 70% or less, more preferably 60% or less, still more preferably 50% or less. The lower limit of the 1,2 bond ratio in the polyisoprene is preferably 10% or more, more preferably 15% or more, still more preferably 20% or more.

  Specific examples of polyisoprene having a 1,2-bond ratio of less than 80% include EPOL (hydrogenated polyisoprene having a 1,2-bond ratio of 20%, manufactured by Idemitsu Kosan Co., Ltd.). .

  The number average molecular weight of the plasticizer is preferably 1,000 or more. Bleeding out can be suppressed more effectively by setting it as such a range. The upper limit of the number average molecular weight of the plasticizer is preferably 20,000 or less, more preferably 10,000 or less.

  The structure of the molecular end of the plasticizer is not particularly limited, and examples thereof include a hydrogen atom, a hydroxyl group, an acrylic group, an isocyanate group, a carboxyl group, and the like, and a hydroxyl group is preferable.

  The content of the plasticizer in the photocurable resin composition is preferably 15 to 50% by mass, more preferably 25 to 45% by mass. By setting it in such a range, the elastic modulus of the light transmissive cured resin layer in a low temperature environment can be lowered more effectively. The plasticizers may be used alone or in combination of two or more. When two or more plasticizers are used in combination, the total amount thereof preferably satisfies the above range.

  In the plasticizer, the total content of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80% is preferably 30% by mass or more, It is more preferably 50% by mass, and further preferably 80% by mass or more. By setting it in such a range, the elastic modulus of the light transmissive cured resin layer in a low temperature environment can be lowered more effectively.

  The photocurable resin composition may further contain a plasticizer other than the above plasticizer. Other plasticizers include solid tackifiers and liquid oil components. Examples of solid tackifiers include terpene resins such as terpene resins, terpene phenol resins, hydrogenated terpene resins, and natural rosins, polymerized rosins, rosin esters, rosin resins such as hydrogenated rosins. Examples of the liquid oil component include polyeptadiene oil and polyisoprene oil.

[Other ingredients]
The photocurable resin composition may contain components other than the above-mentioned components as long as the effect of lowering the elastic modulus of the light transmissive cured resin layer in a low temperature environment is not impaired. For example, the photocurable resin composition may further contain a chain transfer agent for adjusting the molecular weight. Examples of the chain transfer agent include 2-mercaptoethanol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-ethylhexyl thioglycolate, 2,3-dimethylcapto-1-propanol, and α-methylstyrene dimer. Further, the photocurable resin composition may further contain an adhesion improver such as a silane coupling agent, an antioxidant and the like.

  The photocurable resin composition can be prepared by uniformly mixing the above-mentioned components according to a known mixing technique.

  The photocurable resin composition is preferably liquid. Since the photocurable resin composition is in a liquid state, for example, in the method for manufacturing an image display device described later, the step formed between the light shielding layer and the light shielding layer forming side surface of the light transmissive optical member can be more reliably canceled. be able to. Here, that the photocurable resin composition is liquid is preferably that the viscosity at 25 ° C. measured by a B-type viscometer is 0.01 to 100 Pa · s.

  The photocurable resin composition preferably has a glass transition temperature of 40 to 80 ° C. of a resin cured product. The measurement conditions of the glass transition temperature are as described in the examples described later.

  Specifically, the photocurable resin composition has an average curing rate of the entire resin cured product obtained by photoradical polymerization by light irradiation in the air, and an outermost surface curing rate of the resin cured product of 90%. It is preferable that the glass transition temperature when cured so as to be the above (preferably 97% or more) satisfies the above range.

  The reason why we focused on resin cured products that were photo-radically polymerized in the atmosphere is that curing in a cured resin does not affect various properties of the cured resin because oxygen in the atmosphere causes curing inhibition in the cured resin. This is to find out the conditions. The reason why it is preferable to set the curing rate of the outermost surface of the resin cured product to 90% or more is that even when the curing inhibition occurs on the surface of the resin cured product, characteristics such as adhesion on the surface of the resin cured product This is because the decrease of can be practically ignored. Further, the reason why it is preferable to set the glass transition temperature of the resin cured product at such a curing rate to the above range is that within this range, the film-cured resin cured product can be stuck or adhered, etc. This is because it is possible to prevent deterioration of the characteristics of.

Here, the curing rate (gel fraction) is the ratio of the abundance of the (meth) acryloyl group after the light irradiation to the abundance of the (meth) acryloyl group in the photocurable resin composition layer before the light irradiation ( It is a numerical value defined as the consumption rate), and the larger the numerical value is, the more the curing progresses. Specifically, the curing rate is the absorption peak height (X) of 1640 to 1620 cm ⁻¹ from the baseline in the FT-IR measurement chart of the photocurable resin composition layer before light irradiation and the light irradiation after irradiation. Calculated by substituting the absorption peak height (Y) of 1640 to 1620 cm ⁻¹ from the baseline in the FT-IR measurement chart of the photocurable resin composition layer (light transmissive cured resin layer) into the following formula. can do.
Curing rate (%) = [(X−Y) / X] × 100

  The curing rate of the surface of the resin cured product described above means, for example, the curing rate measured for the resin cured product formed into a film having a thickness of 10 μm or less (for example, 5 μm thickness). Further, the curing rate of the entire resin cured product means, for example, the curing rate measured for the resin cured product formed into a film having a thickness of 100 μm or more (for example, 200 μm thickness).

  The photocurable resin composition preferably has a modulus of elasticity of the resin cured product at −20 ° C. of 3.0E + 08 Pa or less, and more preferably 2.9E + 08 Pa or less. Moreover, the lower limit of the elastic modulus at −20 ° C. of the resin cured product of the photocurable resin composition is usually preferably 1.0E + 08 Pa or more. Further, the photocurable resin composition preferably has a modulus of elasticity of the resin cured product at 25 ° C. of 1.0E + 08 Pa or less. The lower limit of the elastic modulus at 25 ° C. of the resin cured product of the photocurable resin composition is usually preferably 1.0E + 06 Pa or more. The measurement conditions of the elastic modulus are as described in Examples described later. Here, the resin cured product means that the average cured rate of the entire resin cured product obtained by photoradical polymerization by light irradiation in the air and the curing rate of the outermost surface of the resin cured product are 90% or more (preferably Is 97% or more).

  The photocurable resin composition preferably has a resin cured product having a transmittance of 90% or more, and more preferably 92% or more. By satisfying such a range, the visibility of the image formed on the image display member forming the image display device can be improved. Here, the resin cured product has the same meaning as the resin cured product described above.

<2. Image display device manufacturing method>
Hereinafter, the first to third embodiments of the method for manufacturing the image display device will be described in detail for each step with reference to the drawings. In the drawings, the same drawing number represents the same constituent element.

[First Embodiment]
[Step (A1)]
In step (A1), the photocurable resin composition is applied to the surface of the light transmissive optical member or the surface of the image display member. FIG. 1A is an explanatory diagram showing an example of a step (A1) of a method for manufacturing an image display device. A light-transmissive optical member 2 having a light-shielding layer 1 formed on the peripheral portion of one surface is prepared, and the surface of the light-transmissive optical member 2 is coated with a photocurable resin composition 3A.

  The light shielding layer 1 is provided, for example, to improve the contrast of an image. The light-shielding layer 1 is formed by applying a coating material colored in black or the like by a screen printing method or the like, and drying and curing it. The thickness of the light shielding layer 1 is usually 5 to 100 μm.

  The light transmissive optical member 2 may be any one that has light transmissivity so that an image formed on the image display member can be visually recognized. Examples thereof include plate-shaped materials and sheet-shaped materials such as glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, and polycarbonate. These materials may be subjected to hard coat treatment, antireflection treatment, or the like on one side or both sides. Physical properties such as the thickness and elastic modulus of the light transmissive optical member 2 can be appropriately determined according to the purpose of use.

[Step (B1)]
In the step (B1), the image display member and the light transmissive optical member are bonded together via the photocurable resin composition. FIG. 1B is an explanatory diagram showing an example of a step (B1) of the method for manufacturing the image display device. The light transmissive optical member 2 is attached to the image display member 6 via the photocurable resin composition 3A. Thereby, the photocurable resin composition layer 3 is formed between the image display member 6 and the light transmissive optical member 2.

[Step (C1)]
In the step (C1), the photocurable resin composition is cured. FIG. 1C is an explanatory diagram showing an example of a step (C1) of the method for manufacturing the image display device. The photocurable resin composition (photocurable resin composition layer 3) sandwiched between the image display member 6 and the light transmissive optical member 2 is irradiated with light (preferably ultraviolet light) to be cured. As a result, as shown in FIG. 1D, the image display device 10 in which the image display member 6 and the light transmissive optical member 2 are laminated via the light transmissive cured resin layer 7 is obtained.

  Light irradiation is preferably performed so that the curing rate of the light-transmitting cured resin layer 7 is 90% or more, and more preferably 95% or more. By satisfying such a range, the visibility of the image formed on the image display member 6 can be improved. Here, the curing rate is synonymous with the curing rate described above. There are no particular restrictions on the type of light source, output, illuminance, integrated light amount, etc. when performing curing, and known photoradical polymerization process conditions of (meth) acrylate by UV irradiation can be adopted, for example.

  Examples of the image display member 6 include a liquid crystal display panel, an organic EL display panel, a plasma display panel, a touch panel and the like. Here, the touch panel means an image display / input panel in which a display element such as a liquid crystal display panel and a position input device such as a touch pad are combined.

  The elastic modulus at −20 ° C. and the elastic modulus at 25 ° C. of the light-transmitting cured resin layer 7 are synonymous with the elastic modulus at −20 ° C. and the elastic modulus at 25 ° C. of the above-mentioned resin cured product. The preferred range is also the same.

  As described above, in the first embodiment, the example in which the photocurable resin composition 3A is applied to the surface of the light transmissive optical member 2 on the side where the light shielding layer 1 is formed has been described, but the surface of the image display member 6 is described. The photocurable resin composition 3A may be applied to.

[Second Embodiment]
[Step (A2)]
2A and 2B are explanatory views showing an example of the step (A2) of the method for manufacturing an image display device. First, as shown in FIG. 2A, a light transmissive optical member 2 having a light shielding layer 1 formed on the peripheral portion of one surface is prepared. Further, as shown in FIG. 2B, the light-curable resin composition is formed on the surface 2a of the light-transmitting optical member 2 by the light-shielding layer 1 and the light-shielding layer forming side surface 2a of the light-transmitting optical member 2. The photo-curable resin composition layer 3 is formed by coating the light-shielding layer 1 with a thickness larger than that of the light-shielding layer 1 so that the step 4 is canceled. Specifically, the photocurable resin composition is applied evenly over the entire surface 2a of the light-transmitting optical member 2 on the light-shielding layer forming side including the surface of the light-shielding layer 1 so that no step is formed. Preferably. The thickness of the photocurable resin composition layer 3 is preferably 1.2 to 50 times, and more preferably 2 to 30 times the thickness of the light shielding layer 1.

  The photocurable resin composition may be applied so that the required thickness can be obtained, and may be applied once or plural times.

[Step (B2)]
In the step (B2), the photocurable resin composition layer formed in the step (A2) is irradiated with light for temporary curing, thereby forming a temporary cured resin layer.

  2C and 2D are explanatory views showing an example of the step (B2) of the method for manufacturing the image display device. As shown in FIG. 2C, the photo-curable resin composition layer 3 formed in the step (A2) is irradiated with light (preferably ultraviolet rays) to be pre-cured to form the pre-cured resin layer 5. Temporary curing of the photocurable resin composition layer 3 is carried out by keeping the photocurable resin composition in a state in which it does not flow significantly from a liquid state, and as shown in FIG. Is to improve. Further, by performing temporary curing, the light-transmissive cured resin layer 3 between the light-shielding layer 1 and the image display member can be sufficiently photocured without being excluded from between, and curing shrinkage can be reduced. it can.

  The temporary curing of the photocurable resin composition layer 3 is preferably performed so that the curing rate of the temporary curing resin layer 5 is 10 to 80%, more preferably 40 to 80%. It is more preferable to carry out so as to be 70 to 80%.

  The light irradiation is not particularly limited as to the type of the light source, the output, the illuminance, the integrated light amount, etc., as long as it can be temporarily cured so that the curing rate is preferably 10 to 80%, and for example, by known ultraviolet irradiation (meta ) Photo radical polymerization process conditions of acrylate can be adopted.

  Further, the light irradiation is preferably selected within the range of the above-mentioned curing rate so as not to cause dripping or deformation of the temporarily cured resin layer 5 during the laminating operation in the step (C2) described later. . For example, when expressed in terms of viscosity, it is preferably 20 Pa · S or higher (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm).

[Step (C2)]
In the step (C2), the image display member and the light-transmissive optical member are attached to each other via the temporarily cured resin layer.

  FIG. 2E is an explanatory diagram showing an example of the step (C2) of the method for manufacturing the image display device. As shown in FIG. 2E, the light transmitting optical member 2 is attached to the image display member 6 from the side of the temporarily cured resin layer 5. The laminating can be performed by applying pressure at 10 to 80 ° C. using a known pressure bonding device, for example.

[Process (D2)]
In the step (D2), the temporary curing resin layer disposed between the image display member and the light-transmissive optical member is irradiated with light to be fully cured, so that the image display member and the light-transmissive optical member are exposed to light. An image display device is obtained by laminating the transparent cured resin layer.

  2F and 2G are explanatory views showing an example of the step (D2) of the method for manufacturing an image display device. As shown in FIG. 2F, the provisionally cured resin layer 5 sandwiched between the image display member 6 and the light transmissive optical member 2 is irradiated with light (preferably ultraviolet rays) to be fully cured. The reason why the temporarily cured resin layer 5 is fully cured is that the temporarily cured resin layer 5 is sufficiently cured so that the image display member 6 and the light transmissive optical member 2 are bonded and laminated. As a result, the image display member 6 and the light-transmissive optical member 2 are laminated via the light-transmissive cured resin layer 7, and the image display device 10 as shown in FIG. 2G is obtained. In addition, if necessary, the provisionally cured resin layer 5 between the light shielding layer 1 of the light transmissive optical member 2 and the image display member 6 is irradiated with light to fully cure the provisionally cured resin layer 5. Good.

  The main curing is preferably performed so that the curing rate of the light-transmitting cured resin layer 7 is 90% or more, and more preferably 95% or more. There are no particular restrictions on the type of light source, output, illuminance, integrated light amount, etc. during the main curing, and, for example, known radical photopolymerization process of (meth) acrylate by ultraviolet irradiation can be adopted.

  In the second embodiment, the example in which the photocurable resin composition is applied to the surface 2a of the light transmissive optical member 2 on the side where the light shielding layer 1 is formed has been described. A curable resin composition may be applied.

[Third Embodiment]
[Step (A3)]
3A and 3B are explanatory views showing an example of the step (A3) of the method for manufacturing an image display device. As shown in FIG. 3A, a light-transmissive optical member 2 having a light-shielding layer 1 formed on a peripheral portion of one surface is prepared, and as shown in FIG. 3B, a surface 2a of the light-transmissive optical member 2 is photocured. The resin composition is applied thicker than the thickness of the light-shielding layer 1 so that the step 4 formed between the light-shielding layer 1 and the light-shielding layer forming side surface 2a of the light-transmitting optical member 2 is canceled.

[Step (B3)]
3C and 3D are explanatory views showing an example of the step (B3) of the method for manufacturing an image display device. As shown in FIG. 3C, the photo-curable resin composition applied in the step (A3) is irradiated with light (preferably ultraviolet rays) to cure the photo-curable resin composition to form the light-transmissive cured resin layer 7 Are formed (FIG. 3D). The curing rate of the light-transmitting cured resin layer 7 is preferably 90% or more, more preferably 95% or more.

[Step (C3)]
FIG. 3E is an explanatory diagram showing an example of the step (C3) of the method for manufacturing the image display device. As shown in FIG. 3E, the light transmitting optical member 2 is attached to the image display member 6 from the light transmitting cured resin layer 7 side. Thereby, the image display device 10 is obtained. The bonding can be performed by the same method as in the step (C2) described above.

  In the method for manufacturing the image display device described above, the case where the light-transmissive optical member in which the light-shielding layer is formed has been described, but the image display device is formed by using the light-transmissive optical member in which the light-shielding layer is not formed. You may produce.

  Examples of the present invention will be described below. In this example, a photocurable resin composition was prepared, and an image display device having a light transmissive cured resin layer using the photocurable resin composition was produced. Then, the produced image display device was evaluated for a drop impact test at -20 ° C, an adhesive strength at 25 ° C, a transmittance, an elastic modulus at -20 ° C, an elastic modulus at 25 ° C, and a glass transition temperature. . The present invention is not limited to these examples.

  In this example, the following abbreviations were used.

[(Meth) acrylic oligomer having urethane skeleton]
TEAI-1000: Nippon Soda Co., Ltd. EBECRYL230: Daicel Ornex Co., Ltd. CN9014: Aliphatic urethane acrylate, Sartomer Co.

[(Meth) acrylate monomer]
FA511AS: dicyclopentenyl acrylate, Hitachi Chemical Co., Ltd. light acrylate IB-XA: isobornyl acrylate, Kyoeisha Chemical Co., Ltd. HDDA: hexanediol diacrylate, Miramer M200, Miwon Specialty Chemical Co.

[Plasticizer]
HLBH-P2000: Hydrogenated polybutadiene having a 1,2 bond rate of 65% (both-end hydroxylated hydrogenated polybutadiene, Krasol HLBH-P2000), HLBH-P3000 made by Clay Valley Co., Ltd., 1,2 with a 65% bond rate. A hydrogenated product of a certain polybutadiene (hydrogenated polybutadiene at both ends, Krasol HLBH-P3000), LBH-P2000 made by Clay Valley Co., Ltd .: Polybutadiene having a 1,2 bond rate of 65% (both end hydroxyl group polybutadiene, Krasol LBH-P2000). LBH-P3000 made by Clay Valley Co., Ltd .: polybutadiene having a 1,2 bond rate of 65% (both-end hydroxyl group polybutadiene, Krasol LBH-P3000); EPOL manufactured by Clay Valley company: 1,2 polyisoprene having a 20% bond rate. Hydrogenation of (Polyisoprene having hydroxyl groups at both ends), GI-1000: 1 manufactured by Idemitsu Kosan Co., Ltd. Hydrogenated polybutadiene having a bond ratio of 85% or more (polybutadiene having hydroxyl groups at both ends), Nippon Soda ( GI-2000: 1,2 hydrogenated polybutadiene having a bond rate of 85% or more (both-end hydroxylated polybutadiene); Nippon Soda Co., Ltd., GI-3000: 1,2 bond rate Hydrogenated polybutadiene having a content of 85% or more (hydrogenated polybutadiene having hydroxyl groups at both ends), G-1000: 1 manufactured by Nippon Soda Co., Ltd. Polybutadiene having a 1,2 bond rate of 85% or more (polybutadiene having hydroxyl groups at both ends), Japan Soda Co., Ltd. G-2000: Polybutadiene (both-end hydroxyl group polybutadiene) having a 1,2 bond ratio of 85% or more, manufactured by Nippon Soda Co., Ltd.

[Polymerization initiator]
Irg184: 1-hydroxycyclohexyl phenyl ketone, manufactured by BASF

[Preparation of photocurable resin composition]
The components were uniformly mixed in the blending amounts (parts by mass) shown in Table 1 to prepare the photocurable resin compositions of Examples 1 to 4 and Comparative Examples 1 to 3.

[Example 1]
A photocurable resin composition was prepared using 35 parts by mass of TEAI-1000, 25 parts by mass of FA511AS, 40 parts by mass of HLBH-P2000, and 1 part by mass of Irg184.

[Example 2]
A photocurable resin composition was prepared in the same manner as in Example 1 except that HLBH-P2000 was changed to HLBH-P3000 in the same amount.

[Example 3]
A photocurable resin composition was prepared in the same manner as in Example 1 except that 25 parts by mass of FA511AS was changed to 20 parts by mass of light acrylate IB-XA and 5 parts by mass of HDDA.

[Example 4]
A photocurable resin composition was prepared in the same manner as in Example 1 except that 40 parts by mass of HLBH-P2000 was changed to 20 parts by mass of HLBH-P3000 and 20 parts by mass of GI-1000.

[Comparative Example 1]
A photocurable resin composition was prepared in the same manner as in Example 1 except that HLBH-P2000 was changed to an equivalent amount of GI-1000.

[Comparative Example 2]
A photocurable resin composition was prepared in the same manner as in Example 1 except that HLBH-P2000 was changed to an equivalent amount of GI-2000.

[Comparative Example 3]
A photocurable resin composition was prepared in the same manner as in Example 1 except that HLBH-P2000 was changed to an equivalent amount of GI-3000.

  The components were uniformly mixed in the blending amounts (parts by mass) shown in Table 2 to prepare photocurable resin compositions of Examples 5 and 6 and Comparative Examples 4 and 5.

[Example 5]
A photocurable resin composition was prepared using 25 parts by mass of EBECRYL230, 30 parts by mass of FA511AS, 45 parts by mass of LBH-P2000, and 1 part by mass of Irg184.

[Example 6]
A photocurable resin composition was prepared in the same manner as in Example 5, except that LBH-P2000 was changed to an equivalent amount of LBH-P3000.

[Comparative Example 4]
A photocurable resin composition was prepared in the same manner as in Example 5 except that LBH-P2000 was changed to G-1000 in the same amount.

[Comparative Example 5]
A photocurable resin composition was prepared in the same manner as in Example 5 except that LBH-P2000 was changed to G-2000 in the same amount.

  The components were uniformly mixed in the blending amounts (parts by mass) shown in Table 3 to prepare photocurable resin compositions of Example 7 and Comparative Example 6.

[Example 7]
A photocurable resin composition was prepared using 30 parts by mass of CN9014, 35 parts by mass of FA511AS, 35 parts by mass of EPOL and 1 part by mass of Irg184.

[Comparative Example 6]
A photocurable resin composition was prepared using 30 parts by mass of CN9014, 35 parts by mass of FA511AS, 35 parts by mass of GI-3000, and 1 part by mass of Irg184.

[Production of image display device]
An image display device was produced by the following steps using the photocurable resin compositions obtained in each of the examples and comparative examples described above.

  A glass plate having a size of 45 (w) × 80 (l) × 0.4 (t) mm is prepared, and a light shielding layer having a width of 4 mm is provided on the entire peripheral portion of the glass plate so that the dry thickness is 40 μm. A glass plate with a light shielding layer was prepared by applying a black thermosetting ink (MRX ink, Teikoku Ink Mfg. Co., Ltd.) by a screen printing method and drying.

  The photocurable resin composition described above was discharged onto the light-shielding layer forming surface of the glass plate with the light-shielding layer using a resin dispenser.

  The glass plate was placed on the surface of the liquid crystal display device having a size of 40 (w) × 70 (l) mm on which the polarizing plates were laminated, with the photocurable resin composition side facing the polarizing plate side. The glass plate was attached by its own weight. The thickness of the photocurable resin composition wet and spread between the polarizing plate and the glass plate was 150 μm.

From the glass plate side, an ultraviolet ray irradiation device (UVL-7000M4-N, manufactured by Ushio Lighting Co., Ltd.) is used to irradiate ultraviolet rays at 3000 mJ / cm ² to cure the photocurable resin composition to cure the light-transmitting curing. A resin layer was formed. The curing rate of the light transmissive cured resin layer was 97%. As a result, a liquid crystal display device was obtained in which a glass plate as a light transmissive optical member was laminated on the liquid crystal display element via a light transmissive cured resin layer.

[Evaluation]
[Drop impact test]
The obtained image display device was dropped from a height of 1 m, and when there was no peeling at the interface between the light-transmissive cured resin layer and the liquid crystal display element and the interface between the light-transmissive cured resin layer and the glass plate, "○" When there was peeling, it was evaluated as "x". The results are shown in Tables 1 to 3.

[Adhesive strength test]
As shown in FIGS. 4 and 5, the photocurable resin composition is dropped on the central portion of the glass plate 31 having a thickness of 1 mm, and the glass plate 32 having a thickness of 1 mm is orthogonally crossed through the spacer 34 having a thickness of 150 μm. Placed. Thereby, the glass bonded body 33 in which the photocurable resin composition layer having a diameter of 3 mm and a thickness of 150 μm was formed between the glass plates 31 and 32 was obtained. Next, by using an ultraviolet irradiation device, 200 mW / cm ² of ultraviolet light is irradiated from the glass plate 32 side so that the integrated light amount becomes 3000 mJ / cm ^2, and the photocurable resin composition layer is completely cured. Thus, the light transmissive cured resin layer 35 was formed. Then, as shown in FIGS. 6 and 7, the glass plate 32 located on the lower side of the glass joined body 33 is fixed, and the glass plate 31 located on the upper side is vertically moved by a jig 36 at a speed of 5 mm / min. Was peeled off, and the adhesion state was evaluated according to the following criteria. AGS-X manufactured by Shimadzu Corporation was used to measure the adhesive strength. The adhesive strength was calculated by measuring the stress required to separate the glass plate 31 and the glass plate 32 at 25 ° C. and dividing the stress by the unit area of the light-transmitting cured resin layer 35. When the adhesive strength (25 ° C.) was 500 N / cm ² or more, it was evaluated as “◯”, and when the adhesive strength was less than 500 N / cm ² , it was evaluated as “x”. The results are shown in Tables 1 to 3.

[Transmittance]
Using a UV-visible spectrophotometer (UV-2450, manufactured by Shimadzu Corp.), the transmittance of the light-transmitting cured resin layer in the image display device in the visible light region was measured. The results are shown in Tables 1 to 3.

[Elastic modulus]
The elastic modulus (−20 ° C. and 25 ° C.) of the light transmissive cured resin layer in the image display device was calculated using a viscoelasticity measuring device. The measurement was performed using a viscoelasticity measuring device (DMS6100, manufactured by Seiko Instruments Inc.) in a tensile mode at a measurement frequency of 1 Hz. The results are shown in Tables 1 to 3.

[Glass-transition temperature]
The glass transition temperature of the light-transmitting cured resin layer in the image display device was measured. The measurement was performed using a viscoelasticity measuring device (DMS6100, manufactured by Seiko Instruments Inc.) in a tensile mode at a measurement frequency of 1 Hz. The results are shown in Tables 1 to 3.

  As in Examples 1 to 7, a (meth) acrylic oligomer having a urethane skeleton, a (meth) acrylate monomer, a polymerization initiator, polybutadiene having a 1,2 bond ratio of less than 80%, and 1,2 When a photocurable resin composition containing at least one kind of polyisoprene having a bonding rate of less than 80% is used, even if the glass transition temperature of the light transmissive resin composition layer is high, light in a low temperature environment It was found that the elastic modulus of the permeable resin composition layer can be lowered. It was also found that the drop impact property at -20 ° C and the transmittance were also good.

  Particularly, as in Examples 1 to 4 and 7, of (meth) acrylic oligomer having a urethane skeleton, (meth) acrylate monomer, a polymerization initiator, and polybutadiene having a 1,2 bond ratio of less than 80%. When a photocurable resin composition containing a hydrogenated product and at least one hydrogenated product of polyisoprene having a 1,2-bond ratio of less than 80% is used, it is also excellent in drop impact resistance at -20 ° C. It was found that the adhesive strength was also good.

  On the other hand, as in Comparative Examples 1 to 6, a photocurable resin composition that does not contain at least one of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80%. It was found that it is difficult to lower the elastic modulus of the light transmissive resin composition layer in a low temperature environment when using a resin. It was also found that the drop impact resistance at -20 ° C was not good.

1 light shielding layer, 2 light transmitting optical member, 2a light shielding layer forming side surface of the light transmitting optical member, 3 photocurable resin composition layer, 3A photocurable resin composition, 4 steps, 5 temporary cured resin layer, 6 image display member, 7 light-transmitting cured resin layer, 10 image display device, 31, 32 glass plate, 33 glass bonded body, 34 spacer, 35 light-transmitting cured resin layer, 36 jig

Claims (11)

A (meth) acrylic oligomer having a urethane skeleton,
A (meth) acrylate monomer,
A polymerization initiator,
Contains a plasticizer,
The plasticizer contains at least one of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80% ,
The photocurable resin composition, wherein the resin cured product obtained by curing the photocurable resin composition has a glass transition temperature of 40 to 80 ° C. and an elastic modulus at −20 ° C. of 3.0E + 08 Pa or less . In the plasticizer, the total content of at least one of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80% is 50% by mass or more. Item 2. The photocurable resin composition according to item 1. The plasticizer contains at least one hydrogenated product of polybutadiene having a 1,2 bond rate of less than 80% and polyisoprene having a 1,2 bond rate of less than 80%. The photocurable resin composition according to 1 or 2 . The photocurable resin composition according to any one of claims 1 to 3 , wherein the content of the plasticizer is 15 to 50% by mass. In the plasticizer, the total content of hydrogenated products of polybutadiene having a 1,2 bond ratio of less than 80% and hydrogenated products of polyisoprene having a 1,2 bond ratio of less than 80% is 30% by mass or more. The photocurable resin composition according to claim 3 or 4 . The (meth) acrylate monomer contains a ring structure-containing (meth) acrylate monomer, the photocurable resin composition according to any one of claims 1-5. The (meth) acrylate monomer contains a (meth) acrylate monomer represented by any one of the following formulas (1) to (3), the photocurable resin according to any one of claims 1 to 6 Composition.

(In the formula (1) ~ (3), R independently represents a hydrogen atom or a methyl group, X is _{-O -, - O (CH 2} ) n O -, - O (CH 2 CH 2 O) _n -, or _{-O (CH (CH 3) CH} 2 O) n - , Y represents the _{-O -, - O (CH 2} ) m O -, - O (CH 2 CH 2 O) m -, or _{-O (CH (CH 3) CH} 2 O) m - represents a, n and m represents an integer of 1 to 10 independently). Examples of the (meth) acrylate monomer include isobornyl acrylate, isobornyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, and dicyclopentenyloxyethyl methacrylate. comprising at least one photocurable resin composition according to any one of claims 1-6. The content of the (meth) acrylate monomer is 15 to 45 mass%, the photocurable resin composition according to any one of claims 1-8. The photocurable resin composition according to claim 1, wherein a cured resin obtained by curing the photocurable resin composition has an elastic modulus at 25 ° C. of 1.0E + 06 Pa or more. A step of applying the photocurable resin composition to the surface of the light transmissive optical member or the surface of the image display member,
A step of laminating the image display member and the light transmissive optical member via the photocurable resin composition;
And a step of curing the photocurable resin composition,
The said photocurable resin composition is a photocurable resin composition of any one of Claims 1-10, The manufacturing method of an image display apparatus.