JP2017161919A - Method for manufacturing image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an image display device, in which a photo-curable resin composition between a light-shielding layer and an image display member can be sufficiently photo-cured without being eliminated from therebetween, and level difference between the light-shielding layer and a light-transmitting cover member surface can be canceled.SOLUTION: After a photo-curable resin composition 3 in a liquid state is once applied on a surface of a light-transmitting cover member 2 including a light-shielding layer 1, to thickness larger than thickness of the light-shielding layer 1, the photo-curable resin composition at least on the light-shielding layer 1 is irradiated with UV rays to be temporarily cured. Thereby, the light-transmitting curable resin layer between the light-shielding layer 1 and an image display member can be sufficiently photo-cured without being eliminated from therebetween, and moreover, level difference between the light-shielding layer 1 and a light-shielding layer side surface of the light-transmitting cover member 2 can be canceled.SELECTED DRAWING: Figure 1C

Description

  The present invention relates to an image display device in which an image display member such as a liquid crystal display panel and a light-transmitting cover member such as a transparent protective sheet disposed on the surface side are bonded and laminated via a light-transmitting cured resin layer. It relates to a method of manufacturing.

  An image display device such as a liquid crystal display panel used for an information terminal such as a smart phone is a photocurable resin composition between an image display member such as a liquid crystal display panel or an organic EL panel and a light-transmitting cover member. The composition is manufactured by irradiating the composition with ultraviolet rays and curing it to form a light-transmitting cured resin layer, thereby bonding and laminating the image display member and the light-transmitting cover member (patent) Reference 1).

  By the way, since a light shielding layer is provided on the periphery of the surface of the light transmissive cover member on the image display portion side in order to improve the brightness and contrast of the display image, the space between the light shielding layer and the image display member is not provided. Curing of the photocurable resin composition sandwiched between the layers does not proceed sufficiently, so that sufficient adhesive force cannot be obtained, peeling between the light-transmitting cover member and the image display member, and moisture in the gap There is a concern that degradation of image quality and the like may occur due to the intrusion.

  Therefore, a thermal polymerization initiator is blended with the photocurable resin composition to obtain a heat and photocurable resin composition, and the heat and photocurable resin composition is formed on the surface of the light transmissive cover member on which the light shielding layer is formed. After applying the product, the coated surface is overlapped on the image display member, and after being cured by irradiating with ultraviolet rays, the entire structure is heated to heat and light curable sandwiched between the light shielding layer and the image display member. It has been proposed to thermally cure a resin composition (Patent Document 2).

International Publication No. 2010/027041 International Publication No. 2008/126860

  However, according to the technology of Patent Document 2, it can be expected that the problems concerned in Patent Document 1 will be solved. However, a thermal polymerization initiator is used in combination with a photopolymerization initiator, and in addition to the photopolymerization process, Therefore, there is a problem that the burden of equipment investment for the thermal polymerization process is increased, and there is a problem that the storage stability of the heat and the photocurable resin composition is lowered. Further, when the light-transmitting cover member coated with the heat and photo-curable resin composition is overlaid on the image display member, since the curing process is not performed at that stage, the light shielding layer and the surface of the light-transmitting cover member The resin composition is excluded from the gap, the level difference between the light shielding layer and the light transmissive cover member surface is not canceled, and there is a concern about the generation of bubbles and the problem of delamination of the light transmissive cover and the resin. ing.

  The object of the present invention is to solve the above-mentioned problems of the conventional technique, and the photocurable resin composition between the light shielding layer and the image display member is sufficiently photocured without being excluded therefrom. And a method of manufacturing an image display device capable of canceling a step between the light shielding layer and the surface of the light transmissive cover member.

  The inventor once applied a liquid photocurable resin composition to the surface of a light-transmitting cover member including a light-shielding layer so as to be thicker than the thickness of the light-shielding layer, and then the photocurable resin located on the light-shielding layer. By irradiating the composition with ultraviolet rays to increase the curing rate and pre-curing it, the light-transmitting cured resin layer between the light-shielding layer and the image display member is sufficiently light without being excluded from between them. The present invention has been completed by finding that it can be cured, and that a step between the light shielding layer and the light shielding layer forming side surface of the light-transmitting cover member can be canceled.

  That is, according to the present invention, an image display member and a light-transmitting cover member having a light-shielding layer formed on a peripheral portion are light-transmitted through a light-transmitting cured resin layer formed from a liquid photocurable resin composition. In the manufacturing method of the image display apparatus laminated | stacked so that the light shielding layer formation surface of a transparent cover member may be arrange | positioned at the image display member side, the manufacturing method which has the following processes (A)-(D) is provided.

<Process (A)>
There is a step formed between the light shielding layer and the light shielding layer forming side surface of the light transmissive cover member on the light shielding layer forming side surface of the light transmissive cover member or the surface of the image display member. The process of applying thicker than the thickness of the light shielding layer so as to be canceled.

<Process (B)>
A step of irradiating the photocurable resin composition located on at least the light shielding layer with ultraviolet rays and temporarily curing the composition so that the curing rate of the temporarily cured resin layer on the light shielding layer is 30 to 80%.

<Process (C)>
A step of bonding the light-transmitting cover member to the image display member so that the light shielding layer and the temporarily cured resin layer are on the inside.

<Process (D)>
The temporary cured resin layer sandwiched between the image display member and the light transmissive cover member is irradiated with ultraviolet rays to be fully cured, and the light transmissive cured resin on both the light shielding layer and the light transmissive cover member. A step of obtaining an image display device by setting the curing rate of the layer to 90% or more and laminating an image display member and a light-transmitting cover member via a light-transmitting cured resin layer.

  In the method for producing an image display device of the present invention, the liquid photocurable resin composition is applied to the surface of the light transmissive cover member including the light shielding layer or the surface of the image display member to be thicker than the thickness of the light shielding layer. Then, at least the photocurable resin composition located on the light shielding layer is irradiated with ultraviolet rays and temporarily cured, so that the curing rate of the temporarily cured resin layer on the light shielding layer is 30 to 80%. Then, after laminating | stacking an image display member and a light-transmitting cover member through a temporary-hardening resin layer, an ultraviolet-ray is irradiated and main-cured and a light-transmitting cured resin layer is formed. For this reason, the light-transmitting cured resin layer between the light-shielding layer and the image display member is sufficiently photocured without being excluded from between the light-shielding layer and the light-shielding layer forming side surface of the light-transmitting cover member. The step can be canceled.

FIG. 1A is an explanatory diagram of step (A) of the method for manufacturing an image display device of the present invention. FIG. 1B is an explanatory diagram of the step (A) of the method for manufacturing the image display device of the present invention. FIG. 1C is an explanatory diagram of the step (B) of the method for manufacturing the image display device of the present invention. FIG. 1D is an explanatory diagram of a step (B) of the method for manufacturing the image display device of the present invention. FIG. 1E is an explanatory diagram of the step (C) of the method for manufacturing the image display device of the present invention. FIG. 1F is an explanatory diagram of a step (D) of the method for manufacturing the image display device of the present invention. FIG. 1G is an explanatory diagram of the step (D) of the manufacturing method of the image display device of the present invention. FIG. 2A is an explanatory diagram of a process (AA) of the manufacturing method of the image display device of the present invention. FIG. 2B is an explanatory diagram of a step (BB) of the method for manufacturing the image display device of the present invention. FIG. 2C is an explanatory diagram of a step (BB) of the method for manufacturing the image display device of the present invention. FIG. 2D is an explanatory diagram of a step (CC) of the method for manufacturing the image display device of the present invention. FIG. 2E is an explanatory diagram of a step (DD) of the method for manufacturing the image display device of the present invention. FIG. 2F is an explanatory diagram of a step (DD) of the method for manufacturing the image display device of the present invention. FIG. 3 is an explanatory diagram of an adhesive strength test of the light transmissive cured resin layer.

  Hereinafter, the manufacturing method of the image display apparatus of the present invention having steps (A) to (D) will be described in detail for each step with reference to the drawings.

<Process (A) (application process)>
First, as shown in FIG. 1A, a light-transmitting cover member 2 having a light shielding layer 1 formed on the peripheral edge of one side is prepared, and as shown in FIG. 1B, on the surface 2a of the light-transmitting cover member 2, The liquid photocurable resin composition 3 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 transmissive cover member 2 is canceled. To do. Specifically, the photocurable resin composition 3 is applied to the entire surface of the light-shielding layer forming side surface 2a of the light-transmitting cover member 2 including the surface of the light-shielding layer 1 so that no step is generated. To. Therefore, the photocurable resin composition 3 is applied in a thickness of preferably 1.2 to 12.5 times, more preferably 2.5 to 4 times the thickness of the light shielding layer 1.

  In addition, you may perform application | coating of this photocurable resin composition 3 in multiple times so that required thickness may be obtained.

  The light transmissive cover member 2 only needs to be light transmissive so that an image formed on the image display member can be visually recognized, and plate-like materials such as glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, and polycarbonate. And sheet-like materials. These materials can be subjected to single-sided or double-sided hard coat treatment, antireflection treatment or the like. The physical properties such as thickness and elasticity of the light-transmitting cover member 2 can be appropriately determined according to the purpose of use.

  The light-shielding layer 1 is provided to increase the contrast of an image, and is formed by applying a paint colored black or the like by a screen printing method or the like, and drying and curing. The thickness of the light shielding layer 1 is usually 5 to 100 μm, and this thickness corresponds to the step 4.

  The property of the photocurable resin composition 3 used in this step is liquid. Since a liquid material is used, the step 4 formed by the light shielding layer 1 and the light shielding layer forming side surface 2a of the light transmissive cover member 2 can be canceled. Here, “liquid” means a cone plate viscometer of 0.01 to 100 Pa.s. It shows the viscosity of s (25 ° C.).

  Such a photocurable resin composition 3 contains an acrylate oligomer component (component (I)), an acrylate monomer component (component (b)), and a photopolymerization initiator (component (c)) as main components. What can be preferably illustrated.

  The acrylic oligomer of component (a) is used as a base material for the photocurable resin composition. Preferable specific examples include (meth) acrylate oligomers having polyisoprene, polyurethane, polybutadiene or the like as a skeleton. In the present specification, the term “(meth) acrylate” includes acrylate and methacrylate.

  As a preferable specific example of the (meth) acrylate oligomer having a polyisoprene skeleton, an esterified product of a maleic anhydride adduct of polyisoprene polymer and 2-hydroxyethyl methacrylate (UC102 (polystyrene equivalent molecular weight 17000), Kuraray Co., Ltd .; UC203 (polystyrene equivalent molecular weight 35000), Kuraray Co., Ltd .; UC-1 (molecular weight of about 25000), Kuraray Co., Ltd.) and the like.

  Specific examples of the (meth) acrylic oligomer having a polyurethane skeleton include aliphatic urethane acrylate (EBECRYL230 (molecular weight 5000), Daicel-Cytec; UA-1, Light Chemical).

  As the (meth) acrylate oligomer having a polybutadiene skeleton, a known one can be employed.

  The acrylic monomer component (B) is used as a reactive diluent in the manufacturing process of the image display device in order to impart sufficient reactivity and coating properties to the photocurable resin composition. Examples of such acrylic monomers include 2-hydroxypropyl methacrylate, benzyl acrylate, dicyclopentenyloxyethyl methacrylate, and the like.

  As the photopolymerization initiator of component (c), a known radical photopolymerization initiator can be used. For example, 1-hydroxy-cyclohexyl phenyl ketone (Irgacure 184, Ciba Specialty Chemicals), 2- Hydroxy-1- {4- [4- (2-monohydroxy-2-methyl-propylonyl) benzyl] phenyl} -2-methyl-1-propan-1-one (Irgacure 127, Ciba Specialty Chemicals), benzophenone, Examples include acetophenone.

  Such photopolymerization initiator is too hard to cure when irradiated with ultraviolet rays if the amount is too small relative to 100 parts by mass of the acrylate oligomer (ii) and monomer (ii), and if too large, outgassing due to cleavage increases and a tendency to foam defects. Therefore, it is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass.

  Moreover, the photocurable resin composition 3 can contain a chain transfer agent for adjusting the molecular weight. Examples thereof include 2-mercaptoethanol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-ethylhexyl thioglycolate, 2,3-dimethylcapto-1-propanol, and α-methylstyrene dimer.

  The photocurable resin composition 3 further contains general additives such as a plasticizer component (component (d)), an adhesion improver such as a silane coupling agent, and an antioxidant, if necessary. can do.

  The component (d) plasticizer component is used to impart buffering properties to the cured resin layer and to reduce the curing shrinkage of the photocurable resin composition. It does not react with the acrylate monomer component of the oligomer component and component (b). Such a plasticizer component contains a solid tackifier (1) and a liquid oil component (2).

  Solid tackifiers (1) include terpene resins such as terpene resins, terpene phenol resins and hydrogenated terpene resins, natural rosins, polymerized rosins, rosin esters, rosin resins such as hydrogenated rosins, and terpene hydrogenated resins. Can be mentioned. In addition, non-reactive oligomers in which the above-mentioned acrylate monomers are preliminarily polymerized can also be used. Specifically, copolymers of butyl acrylate and 2-hexyl acrylate and acrylic acid, and cyclohexyl acrylate and methacrylic acid are used. Examples thereof include an acid copolymer.

  As the liquid oil component (2), polyptadiene oil or polyisoprene oil can be contained.

  Although it is not essential for the photocurable resin composition 3 to contain a plasticizer component (component (d)), it may be contained within a range that does not impair the effects of the present invention. Therefore, the total content of the acrylate oligomer component (I) and the acrylic monomer component (B) in the photocurable resin composition is preferably 25 to 85% by mass, but the component (d) The content of the plasticizer component is in the range of 0 to 65% by mass.

<Process (B) (temporary curing process)>
Next, as shown in FIG. 1C, the curing rate of the temporarily cured resin layer 5a on the light shielding layer 1 is obtained by irradiating at least the photocurable resin composition 3 located on the light shielding layer 1 with ultraviolet rays and temporarily curing the composition. To increase. Here, at least the photocurable resin composition 3 located on the light shielding layer 1 is temporarily cured from a liquid state so as not to flow significantly between the light shielding layer 1 and the light shielding layer forming surface of the light transmissive cover member 2. This is to cancel the step between them. Moreover, it is for hardening the outer periphery of an application | coating area | region to maintain an application | coating shape and to raise the hardening state on the light shielding layer 1 which is hard to be irradiated with an ultraviolet-ray previously.

  For such temporary curing, as shown in FIG. 1C, for example, an attenuation plate 20 that attenuates ultraviolet rays may be disposed between the ultraviolet light source and the photocurable resin composition 3. The attenuation plate 20 is formed of, for example, a quartz plate-like body, and has an uneven surface. With this configuration, the ultraviolet rays that pass through the attenuation plate 20 are attenuated within the attenuation plate 20, are irregularly reflected by the surface irregularities, and are further attenuated. The unevenness | corrugation of the attenuation | damping board 20 should just be a dimension and shape which can reflect an ultraviolet ray irregularly.

  Moreover, temporary hardening may install the shielding board which shields light between an ultraviolet light source and the photocurable resin composition 3, for example, may expose a panel peripheral part and a panel main surface part with a shielding board. Further, a shielding plate may be provided during a part of the ultraviolet irradiation time.

  The curing rate (gel fraction) of the temporarily cured resin layer 5a on the light shielding layer 1 is preferably at a level such that it is 30 to 80%, more preferably 40 to 70%. Thereby, in the main curing step of the step (D), when the light-transmitting cured resin layer 7 on the light-transmitting cover member 2 that is the panel main surface portion is completely cured, the light-transmitting cured resin layer on the light shielding layer 1. 7 can also be fully cured. Here, complete curing means a state of curing so that the curing rate is at least 90% as described later.

  Moreover, the curing rate of the temporarily cured resin layer 5b on the surface of the light-transmitting cover member 2 is preferably 0 to 80%, more preferably 20 to 70%. When the curing rate of the temporarily cured resin layer exceeds 80%, interfacial peeling tends to occur and the adhesion state tends to deteriorate.

  Further, in order to prevent the resin composition from being excluded from between the light shielding layer 1 and the light transmissive cover member 2, the curing rate of the temporarily cured resin layer 5 a on the light shielding layer 1 is determined by the surface of the light transmissive cover member 2. It is preferable that the curing rate of the temporarily cured resin layer 5b is higher.

  Here, the curing rate (gel fraction) is the ratio of the abundance of (meth) acryloyl groups after UV irradiation to the abundance of (meth) acryloyl groups in the photocurable resin composition 3 before UV irradiation ( Consumption ratio) is defined as a numerical value, and the larger this value, the harder the curing.

The curing rate (gel fraction) is the absorption peak height (X) of 1640 to 1620 cm ⁻¹ from the baseline in the FT-IR measurement chart of the resin composition layer before ultraviolet irradiation, and the resin after ultraviolet irradiation. The absorption peak height (Y) of 1640 to 1620 cm ⁻¹ from the base line in the FT-IR measurement chart of the composition layer can be calculated by substituting into the following formula (1).

  Regarding the irradiation with ultraviolet rays, the curing rate (gel fraction) of the temporarily cured resin layer on the light shielding layer 1 is preferably 30 to 80%, more preferably 40 to 70%, so long as it can be temporarily cured. There are no particular restrictions on the type of light source, output, accumulated light quantity, etc., and known photo-radical polymerization process conditions of (meth) acrylate by ultraviolet irradiation can be employed.

  In addition, with respect to the ultraviolet irradiation conditions, within the above-described range of the curing rate, as shown in FIG. 1D, as one of the conditions in which dripping or deformation does not occur even if the temporarily cured resin layer is reversed upside down, the viscosity is It is preferably 20 Pa · S or more (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm). In the case where the temporarily cured resin layer is not reversed upside down, the viscosity may be less than 20 Pa · S.

Further, regarding the ultraviolet irradiation condition, a condition is selected so that the stickiness (tackiness) of the surface of the temporarily cured resin layer 5 can be maintained during the bonding operation in the step (C) described later within the above-described range of the curing rate. It is preferable to do. Probe tack method using a tacking tester (TAC-1000, Reska Corporation) under conditions that allow such stickiness to be maintained (Reska method: Place the sample with the adhesive surface facing up, and press the probe against the adhesive surface from above. This is 30 N / cm ² or more when expressed in terms of measurement values obtained by the “peeling method”. reference).

<Process (C) (bonding process)>
Next, as shown in FIG. 1E, the light-transmitting cover member 2 is bonded to the image display member 6 from the temporarily cured resin layer 5 side. Bonding can be performed by pressurizing at 10 ° C. to 80 ° C. using a known pressure bonding apparatus.

<Process (D) (main curing process)>
Next, as shown in FIG. 1F, the temporarily cured resin layer 5 sandwiched between the image display member 6 and the light-transmitting cover member 2 is irradiated with ultraviolet rays to be fully cured. Further, if necessary, the resin layer is permanently cured by irradiating the resin layer between the light shielding layer of the light-transmissive cover member 2 and the image display member 6 with ultraviolet rays. Thereby, the image display member 6 and the light transmissive cover member 2 are laminated via the light transmissive cured resin layer 7 to obtain the image display device 10 (FIG. 1G).

  Examples of the image display member 6 include a liquid crystal display panel, an organic EL display panel, a plasma display panel, and a touch panel. 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.

  In addition, the main curing in this step is to sufficiently cure the temporarily cured resin layer 5 and bond and laminate the image display member 6 and the light-transmitting cover member 2. The main curing level is such that the curing rate (gel fraction) of the light-transmitting cured resin layer 7 on both the light-shielding layer 1 and the light-transmitting cover member 2 is preferably 90% or more, more preferably 95. It is a level which becomes more than%.

  The light transmissive level of the light transmissive cured resin layer 7 may be light transmissive so that an image formed on the image display member 6 can be visually recognized.

  As mentioned above, although FIG. 1A-FIG. 1G demonstrated the example which apply | coated the photocurable resin composition to the light shielding layer side formation surface of a light-transmitting cover member, in the following FIG. 2A-FIG. The example which apply | coated the photocurable resin composition is demonstrated. 1A to 1G and FIGS. 2A to 2F indicate the same components.

<Process (AA) (application process)>
First, as shown to FIG. 2A, the photocurable resin composition 3 is apply | coated to the surface of the image display member 6 so that it may become flat. The coating thickness in this case is preferably 1.2 to 12.5 times the thickness of the light shielding layer so that a step formed between the light shielding layer and the light shielding layer forming side surface of the light-transmitting cover member is canceled. More preferably, it is applied in a thickness of 2.5 to 4 times.

  In addition, you may perform application | coating of this photocurable resin composition 3 in multiple times so that required thickness may be obtained.

<Process (BB) (temporary curing process)>
Next, as shown in FIG. 2B, at least the photocurable resin composition 3 positioned on the light shielding layer 1 is irradiated with ultraviolet rays to be temporarily cured (FIG. 2C). Here, at least the photocurable resin composition 3 on the image display member 6 positioned on the light shielding layer 1 is temporarily cured from a liquid state so as not to flow remarkably. The light shielding layer 1 and the light transmissive cover member 2 are shielded from light. This is to cancel the step between the surface on the layer forming side. Moreover, it is for hardening the outer periphery of an application | coating area | region to maintain an application | coating shape and to raise the hardening state on the light shielding layer 1 which is hard to be irradiated with an ultraviolet-ray previously.

  Such temporary curing can be obtained, for example, by installing an attenuation plate 2 that attenuates ultraviolet rays between the ultraviolet light source and the photocurable resin composition 3 as shown in FIG. 2B. Further, for example, a shielding plate that shields light may be installed between the ultraviolet light source and the photocurable resin composition 3 so that the peripheral portion of the panel is exposed and the main surface portion of the panel is shielded by the shielding plate. Further, a shielding plate may be provided during a part of the ultraviolet irradiation time.

  The curing rate (gel fraction) of the temporarily cured resin layer 5a facing the light shielding layer 1 is preferably 30 to 80%, more preferably 40 to 70%. Thereby, in the main curing step of the step (D), when the light-transmitting cured resin layer 7 on the light-transmitting cover member 2 that is the panel main surface portion is completely cured, the light-transmitting cured resin layer on the light shielding layer 1. 7 can also be fully cured.

  Moreover, the curing rate of the temporarily cured resin layer 5b facing the surface of the light-transmitting cover member 2 is preferably 0 to 80%, more preferably 20 to 70%. When the curing rate of the temporarily cured resin layer exceeds 80%, interfacial peeling tends to occur and the adhesion state tends to deteriorate.

  Further, in order to prevent the resin composition from being excluded from between the light shielding layer 1 and the light transmissive cover member 2, the curing rate of the temporarily cured resin layer 5 a on the light shielding layer 1 is determined by the surface of the light transmissive cover member 2. It is preferable that the curing rate of the temporarily cured resin layer 5b is higher.

<Process (CC) (bonding process)>
Next, as shown in FIG. 2D, the light-transmitting cover member 2 is bonded to the temporarily cured resin layer 5 of the image display member 6 from the light shielding layer 1 side. Bonding can be performed by applying pressure at 10 to 80 ° C. using a known pressure bonding apparatus.

<Process (DD) (main curing process)>
Next, as shown in FIG. 2E, the temporarily cured resin layer 5 sandwiched between the image display member 6 and the light-transmitting cover member 2 is irradiated with ultraviolet rays to be fully cured. Further, if necessary, the resin layer is permanently cured by irradiating the resin layer between the light shielding layer of the light-transmitting cover member 2 and the image display member 6 with ultraviolet rays. Thereby, the image display member 6 and the light transmissive cover member 2 are laminated via the light transmissive cured resin layer 7 to obtain the image display device 10 (FIG. 2F).

  Examples of the image display member 6 include a liquid crystal display panel, an organic EL display panel, a plasma display panel, and a touch panel.

  In this step, the level of the main curing is preferably 90% or more, more preferably the curing rate (gel fraction) of the light transmissive cured resin layer 7 on both the light shielding layer 1 and the light transmissive cover member 2. Is a level that is 95% or more.

  The light transmissive level of the light transmissive cured resin layer 7 may be light transmissive so that an image formed on the image display member 6 can be visually recognized.

  As described above, according to the method of manufacturing the image display device of the present embodiment, after the light-transmitting curable resin is applied to the protective panel provided with the light shielding portion, the ultraviolet light is irradiated from the light shielding portion side and temporarily cured. In this case, the curing reaction rate of the light-transmitting curable resin on the light-shielding part can be increased by exposing the peripheral edge of the protective panel and limiting the incidence of ultraviolet rays on the panel main surface part by an attenuation member or a shielding member. Thereafter, the shielding member is removed, the image display member is bonded, and ultraviolet light is irradiated from the protective panel side, so that the curing rate of the light-transmitting curable resin at the peripheral portion of the protective panel is set on the main surface portion of the protective panel. It can be as high as the cure rate.

  Hereinafter, the present invention will be specifically described by way of examples.

<Experimental example 1>
Example 1
(Process (A) (Coating process))
First, 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 periphery of the glass plate so as to have a dry thickness of 40 μm. Was coated by a screen printing method using a thermosetting black ink (MRX ink, Teikoku Ink Manufacturing Co., Ltd.) and dried to prepare a glass plate with a light shielding layer.

  In addition, 40 parts by mass of an acrylic oligomer having a polyisoprene skeleton (UC203, Kuraray Co., Ltd.), 20 parts by mass of dicyclopentenyloxyethyl methacrylate (FA512M, Hitachi Chemical Co., Ltd.), hydroxypropyl methacrylate (HPMA, Japan) Kasei Co., Ltd.) 3 parts by mass, tetrahydrofurfuryl acrylate (light ester THF, Kyoeisha Chemical Co., Ltd.) 15 parts by mass, lauryl acrylate (light ester L, manufactured by Kyoeisha Chemical Co., Ltd.), polybutadiene polymer (Polyoil 110, Degussa Co., Ltd.) )) 20 parts by mass, hydrogenated terpene resin (P85, Yasuhara Chemical Co., Ltd.) 45 parts by mass, and photopolymerization initiator (Irg184D, BASF Co., Ltd.) 4 parts by mass are uniformly blended to obtain a photocurable resin composition. It was adjusted. This photocurable resin composition exhibited a total cure shrinkage of 3.4% between a cure rate of 0% and 90%. Further, the viscosity (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm) of the photocurable resin composition was about 6000 mPa · s.

  Next, this photocurable resin composition was discharged to the whole surface of the light shielding layer formation surface of the glass plate with a light shielding layer using the resin dispenser, and the photocurable resin composition film of an average of 200 micrometers was formed. As shown in FIG. 1B, this photocurable resin composition film was formed so as to straddle almost the entire area of the light shielding layer, and was thicker by about 160 μm than the 40 μm thick light shielding layer.

(Process (B) (temporary curing process))
Next, a shielding plate is installed between the ultraviolet light source and the photocurable resin composition, and using an ultraviolet irradiation device (LC-8, manufactured by Hamamatsu Photonics), the photocurable resin composition film is temporarily cured, A temporarily cured resin layer was formed. The curing rate of the photocurable resin composition film after ultraviolet irradiation, that is, the temporarily cured resin layer, obtained by using the absorption peak height of 1640 to 1620 cm ⁻¹ from the baseline in the FT-IR measurement chart as an index is the light shielding property. About 30% on the layer and about 0% on the light transmissive cover member surface.

(Process (C) (bonding process))
Next, on the surface on which the polarizing plate of the liquid crystal display element having a size of 40 (W) × 70 (L) mm is laminated, the temporarily cured resin layer side of the glass plate obtained in the step (B) is the polarizing plate side. The glass plate was attached by pressing with a rubber roller from the glass plate side. When the liquid crystal display element was visually observed from the glass plate side in the attached state, no bubbles were observed around the light shielding layer.

(Process (D) (Main curing process))
Next, the liquid crystal display element is irradiated with ultraviolet rays (50 mW / cm ² ) from the glass plate side by using an ultraviolet irradiation device (LC-8, manufactured by Hamamatsu Photonics), so that the liquid crystal display element on the light-transmitting cover member. The curing rate of the light transmissive cured resin layer was cured to 95% or more to form a light transmissive cured resin layer. The curing rate of the light transmissive cured resin layer on the light shielding layer was about 90%. Thereby, the liquid crystal display device by which the glass plate as a light transmissive cover member was laminated | stacked on the liquid crystal display element through the light transmissive cured resin layer was obtained.

<Evaluation>
The presence or absence of exclusion of the photocurable resin composition from between the light shielding layer and the image display member in each step of Example 1 was visually observed as described below. Moreover, evaluation of the adhesion state of the liquid crystal display device was performed as described below.

(Exclusion of photocurable resin composition from between light shielding layer and image display member)
The presence or absence of exclusion of the photocurable resin composition from between the light shielding layer and the image display member in the result of each step of Example 1 was visually observed. As a result, the exclusion of the photocurable resin composition was not observed in the result of any step and the final liquid crystal display device.

(Evaluation of adhesion state)
When producing a liquid crystal display device, a glass base 30 having a size of 40 (W) × 70 (L) mm is used instead of the liquid crystal display element, as shown in FIG. A glass joined body was obtained by pasting the glass plate 31 on which the cured resin layer was formed in a cross shape from the temporary cured resin layer side. And the glass base 30 located on the lower side is fixed, the glass plate 31 located on the upper side is peeled off in the directly upward direction, the peel property is visually observed, and the adhesion state is evaluated according to the following criteria. "Evaluation.
Rank Criteria A: When cohesive failure occurs B: When cohesive failure and interfacial debonding coexist C: When interfacial delamination occurs

Example 2
In the step (B) (preliminary curing step) of Example 1, a liquid crystal display device was obtained in the same manner as in Example 1 except that ultraviolet rays were irradiated so that the curing rate of the temporarily cured resin layer on the light shielding layer was about 50%. And the glass joined body for adhesive strength measurement was created. As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “A” evaluation.

Example 3
In the step (B) (preliminary curing step) of Example 1, a liquid crystal display device was obtained in the same manner as in Example 1 except that ultraviolet rays were irradiated so that the curing rate of the temporarily cured resin layer on the light shielding layer was about 70%. And the glass joined body for adhesive strength measurement was created. As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “A” evaluation.

Example 4
In the step (B) (preliminary curing step) of Example 1, the liquid crystal display device was the same as in Example 1 except that ultraviolet rays were applied so that the curing rate of the temporary cured resin layer on the light shielding layer was about 80%. And the glass joined body for adhesive strength measurement was created. As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “B” evaluation.

Comparative Example 1
In the step (B) (preliminary curing step) of Example 1, a liquid crystal display device was obtained in the same manner as in Example 1 except that ultraviolet rays were irradiated so that the curing rate of the temporarily cured resin layer on the light shielding layer was about 90%. And the glass joined body for adhesive strength measurement was created. As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. However, the adhesion state was “C” evaluation.

Comparative Example 2
In the step (B) (preliminary curing step) of Example 1, the liquid crystal display device was the same as Example 1 except that the ultraviolet ray was irradiated so that the curing rate of the temporary cured resin layer on the light shielding layer was about 10%. And the glass joined body for adhesive strength measurement was created. As a result, the curing rate of the light-transmitting cured resin layer on the light shielding layer was about 80%, and the exclusion of the photocurable resin composition was observed in the main curing step (step (D)). The adhesion state was “A” evaluation.

  As shown in Comparative Example 1 of Table 1, in the step (B) (temporary curing step), when the curing rate of the temporarily cured resin layer on the light shielding layer is about 90%, the interface in the cured resin layer on the light shielding layer is Peeling occurred and the adhesion state was “C” evaluation.

  As shown in Comparative Example 2, in the step (B) (temporary curing step), when the curing rate of the temporarily cured resin layer on the light shielding layer is about 10%, the light shielding is performed in the step (D) (main curing step). Complete curing with a curing rate of 90% or more could not be obtained on the entire surface of the layer and the light-transmitting cover member. Moreover, exclusion of the photocurable resin composition from between the light shielding layer and the image display member was confirmed.

  On the other hand, as shown in Examples 1 to 4, in the step (B) (temporary curing step), by setting the curing rate of the temporarily cured resin layer on the light shielding layer to 30 to 80%, the step (D) (main In the curing step), complete curing with a curing rate of 90% or more could be obtained on the entire surface of the light shielding layer and the light-transmitting cover member. Moreover, exclusion of the photocurable resin composition from between the light shielding layer and the image display member was not confirmed. Also, all the adhesion states except for Example 4 were “A” evaluations.

<Experimental example 2>
Example 5
In the step (B) (preliminary curing step) of Example 1, a quartz attenuation plate having irregularities formed on the surface is placed between the ultraviolet light source and the photocurable resin composition, and against the incidence of ultraviolet rays. The peripheral edge of the protective panel was exposed, and the panel main surface was limited by an attenuation plate. The examples except that the ultraviolet rays were irradiated so that the curing rate of the temporarily cured resin layer on the light shielding layer was about 70% and the curing rate of the temporarily cured resin layer on the surface of the light-transmitting cover member was about 20%. As in Example 1, a liquid crystal display device and a glass bonded body for measuring adhesive strength were prepared. As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “A” evaluation.

Example 6
In the step (B) (preliminary curing step) of Example 5, the curing rate of the temporary curing resin layer on the light shielding layer is about 70%, and the curing rate of the temporary curing resin layer on the surface of the light-transmitting cover member is about 40%. A liquid crystal display device and a glass joined body for measuring adhesive strength were prepared in the same manner as in Example 1 except that ultraviolet rays were irradiated so that As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “A” evaluation.

Example 7
In the step (B) (preliminary curing step) of Example 5, the curing rate of the temporary curing resin layer on the light shielding layer is about 70%, and the curing rate of the temporary curing resin layer on the light-transmitting cover member surface is about 60%. A liquid crystal display device and a glass joined body for measuring adhesive strength were prepared in the same manner as in Example 1 except that ultraviolet rays were irradiated so that As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “B” evaluation.

Example 8
In the step (B) (preliminary curing step) of Example 5, the curing rate of the temporary curing resin layer on the light shielding layer is about 70%, and the curing rate of the temporary curing resin layer on the light-transmitting cover member surface is about 80%. A liquid crystal display device and a glass joined body for measuring adhesive strength were prepared in the same manner as in Example 1 except that ultraviolet rays were irradiated so that As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. The adhesion state was “B” evaluation.

Comparative Example 3
In the step (B) (preliminary curing step) of Example 5, the curing rate of the temporary curing resin layer on the light shielding layer is about 70%, and the curing rate of the temporary curing resin layer on the light-transmitting cover member surface is about 90%. A liquid crystal display device and a glass joined body for measuring adhesive strength were prepared in the same manner as in Example 1 except that ultraviolet rays were irradiated so that As a result, the curing rate of the light-transmitting cured resin layer on the light-shielding layer is about 95%, and the photocurable resin composition is excluded from the result and the final liquid crystal display device of each process. Not observed. Further, the adhesion state was “C” evaluation.

  As shown in Comparative Example 3 in Table 2, in the step (B) (temporary curing step), when the curing rate of the temporarily cured resin layer on the light transmissive cover member is about 90%, the light transmissive cover member In the cured resin layer, interface peeling occurred and the adhesion state was “C”.

  On the other hand, as shown in Examples 5 to 8, in the step (B) (temporary curing step), the curing rate of the temporarily cured resin layer on the light shielding layer is determined from the curing rate of the temporarily cured resin layer on the light-transmitting cover member. In the step (D) (main curing step), complete curing with a curing rate of 90% or more could be obtained on the entire surface of the light shielding layer and the light-transmitting cover member. Moreover, exclusion of the photocurable resin composition from between the light shielding layer and the image display member was not confirmed. Moreover, all the adhesion states except for Example 8 were “A” evaluations.

  According to the method for manufacturing an image display device of the present invention, the light-transmitting cured resin layer between the light-shielding layer and the image display member is sufficiently photocured without being excluded from between them, and the light-shielding layer of the light-transmitting cover member A step formed between the formation side surface and the formation side surface can be canceled. Therefore, the production method of the present invention is useful for industrial production of information terminals such as smart phones and touch pads provided with a touch panel.

DESCRIPTION OF SYMBOLS 1 Light-shielding layer 2 Light-transmitting cover member 2a Light-shielding layer formation side surface 3, 3a, 3b of light-transmitting cover member Step difference 5 Temporarily cured resin layer 6 Image display member 7 Light-transmitting cured resin layer DESCRIPTION OF SYMBOLS 10 Image display apparatus 20 Attenuation plate 30 Glass base 31 Glass plate

Claims (5)

The image display member and the light-transmitting cover member having a light-shielding layer formed on the peripheral portion are shielded from light by the light-transmitting cover member via the light-transmitting cured resin layer formed from the liquid photocurable resin composition. In the method for manufacturing an image display device laminated so that the layer forming surface is disposed on the image display member side, the following steps (A) to (D):
<Process (A)>
There is a step formed between the light shielding layer and the light shielding layer forming side surface of the light transmissive cover member on the light shielding layer forming side surface of the light transmissive cover member or the surface of the image display member. Applying more than the thickness of the light shielding layer so as to be canceled;
<Process (B)>
A step of irradiating at least the photocurable resin composition located on the light-shielding layer with ultraviolet rays to temporarily cure the cured resin layer on the light-shielding layer to a curing rate of 30 to 80%;
<Process (C)>
Bonding the light transmissive cover member to the image display member so that the light shielding layer and the temporarily cured resin layer are on the inside;
<Process (D)>
The temporary cured resin layer sandwiched between the image display member and the light transmissive cover member is irradiated with ultraviolet rays to be fully cured, and the light transmissive cured resin on both the light shielding layer and the light transmissive cover member. A method for manufacturing an image display device, comprising a step of obtaining an image display device by setting a curing rate of a layer to 90% or more and laminating an image display member and a light transmissive cover member via a light transmissive cured resin layer.   The method for manufacturing an image display device according to claim 1, wherein in the step (B), the curing rate of the temporarily cured resin layer on the surface of the light-transmitting cover member is 0 to 80%.   The method for manufacturing an image display device according to claim 1, wherein in the step (B), the curing rate of the temporarily cured resin layer on the light shielding layer is higher than the curing rate of the temporarily cured resin layer on the surface of the light-transmitting cover member. .   The method for manufacturing an image display device according to claim 1, wherein, in the step (B), a shielding plate that shields ultraviolet rays or an attenuation plate that attenuates ultraviolet rays is installed between the ultraviolet light source and the photocurable resin composition.   The photocurable resin composition contains an acrylate oligomer component, an acrylic monomer component, a plasticizer component and a photopolymerization initiator component, and the plasticizer component contains a solid tackifier and a liquid oil component. Item 4. The method for manufacturing an image display device according to any one of Items 1 to 3.

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