JP2013156641A - Manufacturing method of image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an image display device only by a light-polymerization process, allowing sufficient light-curing without eliminating a light curable resin composition between a light-shielding layer and an image display member and allowing cancellation of level difference between the light-shielding layer and a light transmissive cover member surface, when the image display device is manufactured by laminating the image display member and the light transmissive cover member arranged on the surface side thereof via a light transmissive curable resin layer.SOLUTION: In a manufacturing method of an image display device 10, a liquid light curable resin composition containing no heat-polymerization initiator is coated on the surface of a light transmissive cover member 2 comprising a light-shielding layer 1 or on the surface of an image display member 6 so as to give a thickness thicker than the thickness of the light-shielding layer 1, followed by irradiation with ultraviolet rays in that condition for temporary curing to form a temporarily cured resin layer. Subsequently, the image display member 6 and the light transmissive cover member 2 are laminated via the temporarily cured resin layer, followed by irradiation with ultraviolet rays for primary curing to form a light transmissive cured resin layer 7.

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.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and an image display member and a light-transmitting cover member arranged on the surface side of the photocurable resin composition are provided with a cured resin layer. When the image display device is manufactured by laminating through, the photocurable resin composition between the light shielding layer and the image display member is sufficiently removed without using a thermal polymerization process. It is intended to be photocured and to cancel a step between the light shielding layer and the surface of the light-transmitting cover member and to be able to manufacture an image display device only by a photopolymerization process.

  The present inventor has applied a liquid photocurable resin composition containing no thermal polymerization initiator to the surface of the light-transmitting cover member including the light-shielding layer or the surface of the image display member from the thickness of the light-shielding layer. After being applied thickly, it is preliminarily cured by irradiating with ultraviolet rays in that state, so that the book by irradiating with ultraviolet rays after laminating the image display member and the light-transmitting cover member through such a temporarily cured resin layer. By curing, the light-transmitting cured resin layer between the light-shielding layer and the image display member can be sufficiently photocured without being excluded from between them, and the surface of the light-shielding layer and the light-transmitting cover member on the light-shielding layer forming side The present inventors have found that the step between the two can be canceled and have completed the present invention.

  That is, according to the present invention, an image display member and a light-transmitting cover member having a light-shielding layer formed on the 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 forming a temporarily cured resin layer by irradiating the applied photocurable resin composition with ultraviolet rays to temporarily cure the applied photocurable resin composition.

<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)>
By irradiating the temporarily cured resin layer sandwiched between the image display member and the light-transmitting cover member with ultraviolet rays and performing main curing, the image display member and the light-transmitting cover member are light-transmitting cured resin. A step of obtaining an image display device by stacking through layers.

  In the method for producing an image display device of the present invention, a liquid photocurable resin composition not containing a thermal polymerization initiator is applied to the surface of the light-transmitting cover member including the light shielding layer or the surface of the image display member. After coating thicker than the thickness of the light shielding layer, ultraviolet rays are irradiated in this state to be temporarily cured to form a temporarily cured resin layer. 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. FIG. 4A is an explanatory diagram of an application mode of the photocurable resin composition to the light-transmitting cover member in Example 4. FIG. 4B is an explanatory diagram of an application mode of the photocurable resin composition in Example 4 to the light-transmitting cover member. FIG. 5 is an explanatory view of an application mode of the photocurable resin composition in Comparative Example 1 to the light-transmitting cover member. FIG. 6 is an explanatory diagram of an application mode of the photocurable resin composition to the light-transmitting cover member in Comparative Example 2. FIG. 7 is an explanatory diagram of an application mode of the photocurable resin composition in Comparative Example 3 to the light-transmitting cover member.

  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 that is preferably 1.2 to 50 times, more preferably 2 to 30 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, the liquid state is 0.01 to 100 Pa.s with a B-type viscometer. It shows the viscosity of s (25 ° C.).

  Such a photocurable resin composition 3 contains a radically polymerizable poly (meth) acrylate such as polyurethane (meth) acrylate and polyisoprene (meth) acrylate and a photopolymerization initiator as main components. Things. Here, the term “(meth) acrylate” includes acrylate and methacrylate.

  Preferable specific examples of the photoradically polymerizable poly (meth) acrylate include (meth) acrylate oligomers having polyisoprene, polyurethane, polybutadiene, etc. in the skeleton.

  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 conversion 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.

  As the photopolymerization initiator, 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- (21-hydroxy-2-methyl-propionyl) benzyl] phenyl} -2-methyl-1-propan-1-one (Irgacure 127, Ciba Specialty Chemicals), benzophenone, acetophenone, etc. Can do.

  Such a photopolymerization initiator, relative to 100 parts by mass of radical photopolymerizable poly (meth) acrylate, if it is too small, it becomes insufficiently cured when irradiated with ultraviolet rays, and if it is too large, outgassing due to cleavage tends to increase and foaming defects tend to occur. Preferably it is 0.1-5 mass parts, More preferably, it is 0.2-3 mass parts.

  The liquid photocurable resin composition 3 further includes a known plasticizer (flexibility-imparting agent) that is compatible with the photoradically polymerizable poly (meth) acrylate, such as a terpene-based hydrogenated resin, polyptadiene, polyisoprene, and the like. Can be contained. These plasticizers can also be used as tackifiers, as will be described later.

  Moreover, the photocurable resin composition 3 can contain a reactive diluent. Preferred reactive diluents include 2-hydroxypropyl methacrylate, benzyl acrylate, dicyclopentenyloxyethyl methacrylate and the like.

  The photocurable resin composition 3 can further contain general additives such as an adhesion improving agent such as a silane coupling agent and an antioxidant, if necessary.

  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.

  In addition, the ultraviolet irradiation in the process (B) mentioned later may work so that the initial adhesive strength (what is called tack property) of the photocurable resin composition 3 may be reduced, and final adhesive strength may be reduced. Therefore, it is desirable to add a so-called tackifier to the photocurable resin composition 3. Examples of the tackifier include terpene resins such as terpene resins, terpene phenol resins and hydrogenated terpene resins, rosin resins such as natural rosin, polymerized rosin, rosin ester and hydrogenated rosin, and petroleum resins such as polybutadiene and polyisoprene. Etc. can be used. The blending amount of such a tackifier is preferably 40 to 70 parts by mass in 100 parts by mass of the photocurable resin composition. In addition, since there exists a tendency for the cure level of the photocurable resin composition 3 to become high as the ultraviolet irradiation amount in a process (B) increases, it is preferable to also increase the compounding quantity of a tackifier in the above-mentioned range.

  In addition, although the base material of the photocurable resin composition 3 is the above-mentioned photoradical polymerizable poly (meth) acrylate, in order to express the tackifying effect of the tackifier more strongly, the photoradical polymerizable poly ( It is also possible to include a material obtained by previously polymerizing (meth) acrylate. Examples of such a polymerized material include a copolymer of butyl acrylate and 2-hexyl acrylate and acrylic acid, a copolymer of cyclohexyl acrylate and methacrylic acid, and the like.

<Process (B) (temporary curing process)>
Next, as shown in FIG. 1C, the temporarily cured resin layer 5 is formed by irradiating the photocurable resin composition 3 applied in the step (A) with ultraviolet rays to temporarily cure. Here, the temporary curing is performed in order to improve the handleability by making the photocurable resin composition 3 not to flow from a liquid state to a remarkably flowing state so that it does not flow down even when reversed upside down as shown in FIG. 1D. . Moreover, by performing temporary curing in this way, the light-transmitting cured resin layer between the light shielding layer 1 and the image display member can be sufficiently photocured without being excluded from between them, and curing shrinkage can also be reduced. Can do. Such a pre-curing level is such that the curing rate (gel fraction) of the pre-curing resin layer 5 is preferably 10 to 80%, more preferably 30 to 60%. 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 FR-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 baseline in the FR-IR measurement chart of the composition layer can be calculated by substituting into the following formula (1).

  As long as the curing rate (gel fraction) can be preliminarily cured so that the curing rate (gel fraction) is preferably 10 to 80%, the type of light source, output, accumulated light amount, etc. are not particularly limited, and known ultraviolet irradiation The (meth) acrylate photoradical polymerization process conditions according to can be employed.

  In addition, regarding the ultraviolet irradiation condition, it is possible to select a condition that does not cause dripping or deformation of the temporarily cured resin layer 5 during the bonding operation in the step (C) described later within the range of the curing rate described above. preferable. When expressing such conditions that do not cause dripping or deformation, the viscosity is 20 Pa · S or more (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm).

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 / mm ² or more when expressed in terms of measured values obtained by the method of peeling (“Method for measuring physical properties of adhesive substances” at http://www.rhesca.co.jp/main/technical/technical.html) 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. Such a level of main curing is such that the curing rate (gel fraction) of the light-transmitting cured resin layer 7 is preferably 90% or more, more preferably 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 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 50 times the thickness of the light shielding layer so that the step formed between the light shielding layer and the light shielding layer forming side surface of the light-transmitting cover member is canceled. The thickness is preferably 2 to 30 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, the temporarily cured resin layer 5 is formed by irradiating the photocurable resin composition 3 applied in the step (AA) with ultraviolet rays to temporarily cure (FIG. 2C). Here, the temporary curing is performed by making the photo-curable resin composition 3 not to flow remarkably from the liquid state, improving the handleability, and canceling the step when the light-shielding layer of the light-transmitting cover member is stacked. This is so that it can be pushed in as much as possible. Further, by temporarily curing in this way, the light-transmitting cured resin layer between the light shielding layer and the image display member can be sufficiently photocured without being excluded from between them, and the shrinkage of curing can be reduced. it can. Such a pre-curing level is such that the curing rate (gel fraction) of the pre-curing resin layer 5 is preferably 10 to 80%, more preferably 30 to 60%.

<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 such that the curing rate (gel fraction) of the light transmissive cured resin layer 7 is preferably 90% or more, more preferably 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.

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

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, 6 parts by weight of polyisoprene methacrylate (UC102, Kuraray Co., Ltd.) as a radical photopolymerizable poly (meth) acrylate, 15 parts by weight of dicyclopentenyloxyethyl methacrylate and 5 parts by weight of lauryl methacrylate as a reactive diluent, a plasticizer 20 parts by weight of polybutadiene (Polybest 110, manufactured by Evonik Degussa), 1 part by weight of a photopolymerization initiator (Irgacure 184, BASF), and 53 parts by weight of hydrogenated terpene resin (Clearon M105, manufactured by Yasuhara Chemical) as a tackifier To prepare a photocurable resin composition. The viscosity (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm) of this 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, an ultraviolet ray having an intensity of 50 mW / cm ^{2 is} applied to the photocurable resin composition film using an ultraviolet irradiation device (LC-8, manufactured by Hamamatsu Photonics) so that the integrated light amount becomes 300 mJ / cm ^2. Was pre-cured by irradiating for 6 seconds to form a pre-cured resin layer. Here, the cumulative amount of light of 300 mJ / cm ² corresponds to about 10% of the amount of ultraviolet light necessary to completely cure the photocurable resin composition film.

In addition, the hardening rate of the photocurable resin composition film | membrane after ultraviolet irradiation calculated | required using the absorption peak height of 1640-1620cm < ^-1 > from the baseline in a FR-IR measurement chart as an parameter | index, ie, the temporary hardening resin layer, is About 50%.

  The viscosity of the temporarily cured resin layer (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed: 10 rpm) was 30 Pa · s. For this reason, even if the glass plate was inverted so that the photocurable resin layer of the glass plate was on the lower surface, no dripping or film deformation occurred within 1 minute.

Furthermore, the tackiness of the surface of the temporarily cured resin layer was 90 N / mm ² according to the probe tack method measurement using a tacking tester (TAC-II, Resuka Co., Ltd.).

(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 completely irradiated with ultraviolet rays (50 mW / cm ² ) for 60 seconds from the glass plate side using an ultraviolet irradiation device (LC-8, manufactured by Hamamatsu Photonics) to completely complete the temporarily cured resin layer. To form a light transmissive cured resin layer. The curing rate of the light transmissive cured resin layer was 97%. 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 bubbles at the boundary between the light shielding layer and the photocurable resin composition film, the temporary cured resin layer, or the light transmissive cured resin layer in the result of 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.

(With or without air bubbles)
The presence or absence of bubbles at the boundary between the light shielding layer and the photocurable resin composition film, the temporary cured resin layer, or the light transmissive cured resin layer in the resultant product of each step of Example 1 was visually observed. As a result, no bubbles were 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 peeling occurs B: When cohesive peeling and interfacial peeling coexist C: When interfacial peeling occurs

Example 2
In the step (A) (application step) of Example 1, the liquid crystal display device is the same as Example 1 except that the photocurable resin composition film is formed so as to straddle about 70% with respect to the width of the light shielding layer. And the glass joined body for adhesive strength measurement was created, the presence or absence of the bubble was observed, and the adhesion state was evaluated. As a result, even if the photocurable resin composition film is formed so as to straddle only about 70% with respect to the width of the light shielding layer, the result of each step of Example 2 and the final liquid crystal display device are used. There were no bubbles, and the adhesion state was also evaluated as A. This is considered to be because in the step (C) (bonding step), the temporarily cured resin layer spreads so as to cover the entire light shielding layer.

Example 3
In the step (A) (application step) of Example 1, the liquid crystal display device and the adhesive strength were the same as in Example 1 except that the photocurable resin composition film was formed at about 1.2 times the thickness of the light shielding layer. A glass joined body for measurement was prepared, the presence or absence of bubbles was observed, and the adhesion state was evaluated. As a result, if the photo-curable resin composition film is formed with a thickness of about 1.2 times the thickness of the light-shielding layer, there are no bubbles in the result of each step of Example 3 and the final liquid crystal display device. The adhesion state was also evaluated as “A”.

Example 4
In the step (A) (application step) of Example 1, as shown in FIG. 4A, the photocurable resin composition 3a is applied with the same thickness as the light shielding layer 1 without straddling the light shielding layer 1, and further photocured. A liquid crystal display device and a glass bonded body for measuring adhesive strength were prepared in the same manner as in Example 1 except that the conductive resin composition 3b was applied so as to straddle the light shielding layer 1 as shown in FIG. Observed and evaluated for adhesion. As a result, even if the photocurable resin composition was multilayered, no bubbles were present in the resultant product of each step of Example 4 and the final liquid crystal display device, and the adhesion state was also evaluated as “A”. .

Example 5
The curing rate of the temporarily cured resin layer in the step (B) of Example 1 was set to 10%, 30%, 60%, and 80%, and the ultraviolet ray irradiation in the step (D) was performed, and the curing rate of the temporarily cured resin layer was 99. A liquid crystal display device and a glass bonded body for measuring the adhesive strength were prepared in the same manner as in Example 1 except that the process was performed until the content became equal to or higher than%, and the presence or absence of bubbles was observed to evaluate the adhesion state. As a result, even if the curing rate of the temporarily cured resin layer changes within a range of 10 to 80%, there are no bubbles in the result of each step of Example 5 and the final liquid crystal display device. In addition, except for the case of 80% (“B” evaluation), all were “A” evaluations.

The tackiness on the surface of the temporarily cured resin layer was in the range of 30 to 120 N / mm ² according to the probe tack measurement using a tacking tester (TAC-II, Resuka Co., Ltd.).

Comparative Example 1
In the step (A) (application step) of Example 1, the photocurable resin composition 3 is formed so as to straddle the entire area of the light shielding layer 1 as shown in FIG. 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 the adhesive state was formed, and the presence or absence of bubbles was observed to evaluate the adhesion state. As a result, bubbles were not observed in the result of step (A), but bubbles were observed in the result of step (C) and the result of step (D) (liquid crystal display device). The adhesion state was “A” evaluation.

Comparative Example 2
In the step (A) (application step) of Example 1, as shown in FIG. 6, the photocurable resin composition 3 was applied in the form of dots so as not to straddle the light shielding layer 1 although it was higher than the light shielding layer 1. Except for the above, a liquid crystal display device and a glass bonded body for measuring adhesive strength were prepared in the same manner as in Example 1, the presence or absence of bubbles was observed, and the adhesion state was evaluated. As a result, it is clear that bubbles are involved when irradiated with ultraviolet rays, and when bonded to a liquid crystal display device without irradiating ultraviolet rays, bubbles were observed not only in the periphery of the light shielding layer but also in each region. The adhesion state was “A” evaluation.

Comparative Example 3
In the step (A) (application step) of Example 1, as shown in FIG. 7, the photocurable resin composition 3 was not formed so as to straddle the light shielding layer 1 and its thickness was applied thinner than the light shielding layer 1. Except for the above, a liquid crystal display device and a glass bonded body for measuring adhesive strength were prepared in the same manner as in Example 1, the presence or absence of bubbles was observed, and the adhesion state was evaluated. As a result, although bubbles cannot be confirmed in the result of the step (A), bubbles are confirmed in the result of the bonding step of the step C, and the result of the step (D) (main curing step) (liquid crystal display device) Also confirmed. The adhesion state was “A” evaluation.

Comparative Example 4
In the step (B) (preliminary curing step) in Example 1, except that the curing rate of the temporarily cured resin layer was 90%, and the ultraviolet irradiation time in the step (D) (main curing step) was 30 seconds. As in Example 1, a liquid crystal display device and a glass bonded body for measuring adhesive strength were prepared, the presence or absence of bubbles was observed, and the adhesion state was evaluated. As a result, no bubbles were observed in the result of any step, but the adhesion state was “C” evaluation.

Comparative Example 5
In the step (A) in Example 1, the photocurable resin composition is not applied to the glass plate, but formed on a release film, and the same ultraviolet irradiation as in Step (B) in Example 1 is performed. The liquid crystal display device and the liquid crystal display device were the same as in Example 1 except that the temporarily cured resin layer of the photocurable resin composition was formed on the release film, and the temporarily cured resin layer was transferred to the glass plate on which the light shielding layer was formed. A glass joined body for measuring adhesive strength was prepared, the presence or absence of bubbles was observed, and the adhesion state was evaluated. As a result, bubbles were observed at the steps of the light shielding layer during the transfer of the temporarily cured resin layer. Bubbles were also observed in the results of the subsequent step (C) and step (D). The adhesion state was “B” evaluation.

  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 10 Image display device 30 Glass base 31 Glass plate

Claims (6)

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 manufacturing method of the image display device laminated so that the layer forming surface is arranged 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 forming a temporarily cured resin layer by irradiating the applied photocurable resin composition with ultraviolet rays to temporarily cure;
<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)>
By irradiating the temporarily cured resin layer sandwiched between the image display member and the light-transmitting cover member with ultraviolet rays and performing main curing, the image display member and the light-transmitting cover member are light-transmitting cured resin. The manufacturing method which has a process of laminating | stacking through a layer and obtaining an image display apparatus.   The manufacturing method according to claim 1, wherein the image display member is a liquid crystal display panel, an organic EL display panel, a plasma display panel, or a touch panel.   The manufacturing method of Claim 1 or 2 which apply | coats a photocurable resin composition by the thickness of 1.2-50 times the thickness of a light shielding layer in a process (A).   The process according to any one of claims 1 to 3, wherein in the step (B), the photocurable resin composition is temporarily cured by irradiating the photocurable resin composition so that the curing rate of the temporarily cured resin layer is 10 to 80%. Method.   The manufacturing method according to any one of claims 1 to 4, wherein in the step (D), the temporarily cured resin layer is irradiated with ultraviolet rays so that the curing rate of the light transmissive cured resin layer is 90% or more. .   The manufacturing method in any one of Claims 1-5 in which a liquid photocurable resin composition contains a polyurethane-type (meth) acrylate or a polyisoprene-type (meth) acrylate, and a tackifier.

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