JP2020046557A - Method of manufacturing image display device - Google Patents

Abstract

To provide a method of manufacturing an image display device realizing excellent adhesion performance when pre-cured.SOLUTION: A method of manufacturing an image display device comprises: a step A of forming a curable resin layer 2 comprising a photocurable resin composition on a surface of an image display member 1 or a front plate 4; a step B of forming a pre-cured layer 5 by irradiating the curable resin layer 2 with light from a UV-LED; a step C of bonding the image display member 1 and the front plate 4 together across the pre-cured layer 5; and a step D of forming a cured resin layer 6 by irradiating the pre-cured layer 5 with light across the front plate 4. The irradiation light in the step B includes first light with a peak in a wavelength range of 360-430 nm, and second light with a peak in a wavelength range of 200-345 nm. In the step B, a portion of the curable resin layer 2 where the irradiation of the curable resin layer 2 with the first light causes oxygen inhibition is irradiated with the second light.SELECTED DRAWING: Figure 2

Description

  The present technology relates to a method for manufacturing an image display device.

  Patent Document 1 discloses a first irradiation step (temporary curing step) of irradiating an adhesive applied to at least one of a display panel and a substrate with light, and a bonding step of bonding the display panel and the substrate after the first irradiation step. A method of manufacturing a display device including a bonding step and a second irradiation step (main curing step) of irradiating the adhesive with light after the bonding step is described.

  The cured state of the outermost surface of the resin in the temporary curing step is very important for maintaining alignment during bonding. As for the cured state of the outermost surface of the resin, the greater the influence of oxygen inhibition during temporary curing, the lower the curing rate, and accordingly the adhesive function tends to be reduced. Therefore, as the ultraviolet irradiation device, a device having a wide range of wavelengths and high output, such as a metal halide lamp and a high-pressure mercury lamp, is preferable.

  However, in recent years, UV-LEDs having a peak in a wavelength range of 360 to 430 nm, for example, tend to be often used as a light source due to a demand for high life performance of an ultraviolet irradiation device. Since such a UV-LED is used at a single wavelength, there is a concern that the adhesive performance during temporary curing may be reduced due to the influence of oxygen inhibition.

International Publication WO2009 / 054168

  The present technology has been proposed in view of such a conventional situation, and provides a method of manufacturing an image display device having good adhesion performance during temporary curing.

  The method for manufacturing an image display device according to the present technology includes: a step A of forming a curable resin layer made of a photocurable resin composition on the surface of a front plate or an image display member; and a UV-LED on the curable resin layer. Step B of forming a temporary cured layer by irradiating light from the above, Step C of bonding the front panel and the image display member through the temporary cured layer, and irradiating the temporary cured layer with light through the front panel And a step D of forming a cured resin layer, wherein the light irradiated in the step B includes a first light having a peak in a wavelength range of 360 to 430 nm and a second light having a peak in a wavelength range of 200 to 345 nm. In the step B, the first light is applied to the curable resin layer to irradiate the curable resin layer with the second light at the portion of the curable resin layer where oxygen inhibition occurs.

  According to the present technology, it is possible to improve the adhesive performance during temporary curing.

FIG. 1 is a cross-sectional view illustrating an example of a step of forming a curable resin layer made of a photocurable resin composition on the surface of an image display member. FIG. 2 is a cross-sectional view for explaining an example of a step of irradiating a curable resin layer with light from a UV-LED to form a temporary cured layer. FIG. 3 is a cross-sectional view illustrating an example of a step of forming a temporary cured layer by irradiating a curable resin layer with light from a UV-LED. FIG. 4 is a cross-sectional view illustrating an example of a step of bonding the front plate and the image display member via the temporary curing layer. FIG. 5 is a cross-sectional view illustrating an example of a process of forming a cured resin layer by irradiating the temporarily cured layer with light through a front plate. FIG. 6 is a cross-sectional view illustrating an example of the image display device. FIGS. 7A to 7H are diagrams for explaining a procedure for preparing a test sample. FIG. 8 is a perspective view for explaining a method for measuring the shear strength of the temporary hardened layer. FIG. 9 is a graph showing the measurement results of the shear strength of the temporarily cured layers in the test samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2. FIG. 10 is a graph showing the measurement results of the shear strength of the temporarily cured layer in the test samples obtained in Example 7 and Comparative Examples 3 to 5. FIG. 11 is a graph showing the measurement results of the shear strength of the temporarily cured layer in the test samples obtained in Example 8 and Comparative Examples 6 to 8. FIG. 12 is a graph showing the measurement results of the shear strength of the temporarily cured layer in the test samples obtained in Example 9 and Comparative Examples 9 to 11. FIG. 13 is a graph showing the measurement results of the shear strength of the temporarily cured layer in the test samples obtained in Example 10 and Comparative Example 12. FIG. 14 is a graph showing the measurement results of the shear strength of the cured resin layer obtained by fully curing the temporary cured layer in the test sample obtained in Example 9.

  Hereinafter, a method of manufacturing the image display device according to the present technology (hereinafter, also referred to as the present manufacturing method) will be described in detail. In the following description, (meth) acrylate includes both acrylate and methacrylate. Further, the (meth) acryloyl group includes both an acryloyl group and a methacryloyl group.

  This production method includes a step A of forming a curable resin layer made of a photocurable resin composition on the surface of a front plate or an image display member, and temporarily irradiating the curable resin layer with light from a UV-LED. A step B of forming a cured layer, a step C of bonding the front panel and the image display member through the temporary cured layer, and a step of irradiating the temporary cured layer with light through the front panel to form a cured resin layer. Step D. The light irradiated in the step B includes a first light having a peak in a wavelength range of 360 to 430 nm and a second light having a peak in a wavelength range of 200 to 345 nm. In the step B, the first light is irradiated on the curable resin layer to irradiate the second light on the portion of the curable resin layer where oxygen inhibition occurs. The first light having a peak in the wavelength range of 360 to 430 nm has lower energy than the second light having a peak in the wavelength range of 200 to 345 nm, and reaches the deep portion of the curable resin layer. On the other hand, the second light having a peak in the wavelength range of 200 to 345 nm has higher energy than the first light having a peak in the wavelength range of 360 to 430 nm, does not reach the deep part of the curable resin layer, and is hardened. Reaches only the surface layer of the conductive resin layer. By using the first light having a peak in a wavelength range of 360 to 430 nm and the second light having a peak in a wavelength range of 200 to 345 nm together as the light to be irradiated in the step B, the wavelength range of 360 to 430 nm is obtained. As compared with the case where only the first light having a peak is applied, the influence of oxygen inhibition can be reduced, and the adhesive performance at the time of temporary curing can be improved.

<Step A>
In step A of the present manufacturing method, a curable resin layer 2 made of a photocurable resin composition is formed on the surface of the image display member 1, as shown in FIG. For example, in step A, it is preferable to form the curable resin layer 2 by applying the photocurable resin composition to the entire surface of the image display member 1 so as to be flat. The thickness of the curable resin layer 2 is preferably, for example, such that a step formed between a light-shielding layer 3 described later and a light-shielding layer forming side surface of the front plate 4 is canceled. The thickness may be 2.5 to 40 times, may be 2.5 to 12.5 times, or may be 2.5 to 4 times. As an example, the thickness of the curable resin layer 2 may be 25 to 350 μm, or may be 50 to 150 μm. The number of application times of the photocurable resin composition is not particularly limited as long as the required resin thickness is obtained, and may be one time or plural times.

  The image display member 1 is, for example, an image display panel in which a polarizing plate is formed on a viewing side surface of an image display cell. Examples of the image display cell include a liquid crystal cell and an organic EL cell. Examples of the liquid crystal cell include a reflection type liquid crystal cell and a transmission type liquid crystal cell. The image display member 1 is, for example, a liquid crystal display panel, an organic EL display panel, a touch panel, or the like. The touch panel means an image display / input panel in which a display element such as a liquid crystal display panel and a position input device such as a touch pad are combined.

  The photocurable resin composition for forming the curable resin layer 2 contains, for example, a photoradical reactive component, at least one of a plasticizer and a tackifier, and a photopolymerization initiator. The photocurable resin composition may further contain other components as long as the effects of the present technology are not impaired.

<Photo-radical reactive component>
The photo-radical reactive component contains at least one of a (meth) acrylate oligomer and a (meth) acrylate monomer. The (meth) acrylate oligomer preferably has a skeleton of polyisoprene, polyurethane, polybutadiene, or the like, and has a skeleton of polyurethane (urethane (meth) acrylate oligomer). The (meth) acrylate oligomer preferably has 1 to 4 (meth) acryl groups, and more preferably has 2 to 3 (meth) acryl groups. Commercially available urethane (meth) acrylate oligomers include, for example, CN9014 (manufactured by Sartomer), EBECRYL 230, and EBECRYL 270 (all manufactured by Daicel Ornex).

  The (meth) acrylate monomer is used as a reactive diluent for imparting sufficient reactivity, applicability, and the like to the photocurable resin composition. The (meth) acrylate monomer may be a monofunctional (meth) acrylate, a bifunctional (meth) acrylate, or a polyfunctional (meth) acrylate. The (meth) acrylate monomer is, for example, a (meth) acrylate monomer having a hydroxyl group (for example, 4-hydroxybutyl acrylate) or a (meth) acrylate monomer having a cyclic structure (for example, from the viewpoint of compatibility with other components). Bornyl acrylate, dicyclopentenyloxyethyl methacrylate), an alkyl (meth) acrylate monomer having 5 to 20 carbon atoms (eg, n-octyl acrylate, isodecyl acrylate, lauryl acrylate, isostearyl acrylate), polyfunctional (meth) acrylate It is preferable to include a monomer (for example, pentaerythritol (tri / tetra) acrylate, neopentyl glycol diacrylate hydroxypivalate) and the like.

  The total content of the (meth) acrylate oligomer and the (meth) acrylate monomer in the photocurable resin composition can be 95% by mass or less, and may be 90% by mass or less. Further, the total content of the (meth) acrylate oligomer and the (meth) acrylate monomer in the photocurable resin composition can be 20% by mass or more, may be 30% by mass or more, and may be 35% by mass. % Or more. The (meth) acrylate oligomer and / or the (meth) acrylate monomer may be used alone or in combination of two or more. When two or more (meth) acrylate oligomers and / or (meth) acrylate monomers are used in combination, the total content thereof is preferably within the above range.

<Photopolymerization initiator>
As the photopolymerization initiator, a known photoradical polymerization initiator can be used. As the photopolymerization initiator, an alkylphenone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, an intramolecular hydrogen abstraction type photopolymerization initiator, or the like can be used. Specific examples include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, methyl phenylglyoxylate, and the like. Examples of commercially available products include LUCIRIN TPO, Irgacure 184, IRGACURE MBF (above, manufactured by BASF), Esacure TZT (manufactured by Lamberti), and the like.

  The total content of the photopolymerization initiator in the photocurable resin composition can be 10% by mass or less, may be 8% by mass or less, or may be 6% by mass or less. Further, the total content of the photopolymerization initiator in the photocurable resin composition may be 0.1% by mass or more, may be 1% by mass or more, or may be 2% by mass or more. Is also good. One photopolymerization initiator may be used alone, or two or more photopolymerization initiators may be used in combination. When two or more photopolymerization initiators are used in combination, the total content thereof is preferably within the range described above.

<Plasticizer and tackifier>
The plasticizer and the tackifier do not substantially react with the (meth) acrylate oligomer and the (meth) acrylate monomer by light irradiation. Examples of the tackifier include a solid tackifier and a liquid oil component. Examples of the solid tackifier include terpene resins, terpene phenol resins, terpene resins such as hydrogenated terpene resins, natural rosins, polymerized rosins, rosin esters, rosin resins such as hydrogenated rosins, and terpene hydrogenated resins. . Examples of the liquid oil component include polybutadiene-based oil and polyisoprene-based oil. Examples of commercially available plasticizers and tackifiers include Clearon M105 (manufactured by Yasuhara Chemical Co., Ltd.), GI-1000, and GI-3000 (manufactured by Nippon Soda Co., Ltd.).

  When the photocurable resin composition contains at least one of a plasticizer and a tackifier, the total content of the plasticizer and the tackifier in the photocurable resin composition should be 70% by mass or less. May be 65% by mass or less, 60% by mass or less, or 58% by mass or less. Further, the total content of the plasticizer and the tackifier in the photocurable resin composition may be 0.5% by mass or more, may be 2% by mass or more, and may be 4% by mass or more. May be present, may be 5% by mass or more, and may be 7% by mass or more. The plasticizer and / or the tackifier may be used alone or in combination of two or more. When two or more plasticizers and / or tackifiers are used in combination, the total content of the plasticizers and / or tackifiers is preferably within the above range.

<Other ingredients>
As long as the effects of the present technology are not impaired, the photocurable resin composition may further include, for example, a polymer component (the above-described photoradical reactive component, a polymer component other than the plasticizer and the tackifier), and an oxidized component. It may further contain an inhibitor, a light stabilizer, a silane coupling agent and the like. As the polymer component, for example, Hitaloid 7927 (manufactured by Hitachi Chemical Co., Ltd.) can be used. Hitaloid 7927 is an ultraviolet-curable resin containing a polymer as a main component and an acrylic monomer as a reactive diluent, but the polymer as a main component functions as a tackifier. In the present invention, in the case where the photocurable resin composition contains etaloid 7927, the content of etaloid 7927 in the photocurable resin composition is calculated as the content of the tackifier described above. As the antioxidant, for example, a hindered phenol-based antioxidant can be used. As commercially available antioxidants, for example, IRGANOX1520L and IRGANOX1010 (all manufactured by BASF) can be used. As the light stabilizer, for example, a hindered amine light stabilizer can be used. As a commercially available light stabilizer, for example, ADK STAB LA-52 (manufactured by ADEKA) can be used. As the silane coupling, for example, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane can be used. As commercial products of the silane coupling, for example, KBM5103, KBM503, and KBM803 (all manufactured by Shin-Etsu Silicone Co., Ltd.) can be used.

<Step B>
In step B of the present manufacturing method, the curable resin layer 2 is irradiated with light from a UV-LED as shown in FIG. 2 to form a temporary cured layer 5 as shown in FIG. In the step B, the first light having a peak in a wavelength range of 360 to 430 nm and the second light having a peak in a wavelength range of 200 to 345 nm with respect to the curable resin layer 2 formed in the step A. Irradiate.

The light irradiation in the step B is preferably performed so that the reaction rate of the temporarily cured layer 5 becomes 10 to 90%, more preferably 40 to 90%, and more preferably 70 to 90%. More preferably, The reaction rate is a numerical value defined as a ratio (consumption rate) of the (meth) acryloyl group present after light irradiation to the (meth) acryloyl group present in the curable resin layer before light irradiation. . The larger the numerical value of the reaction rate, the more the curing is progressing. Specifically, the reaction rate is determined based on the absorption peak height (X) of 1640 to 1620 cm ⁻¹ from the baseline in the FT-IR measurement chart of the curable resin layer before light irradiation, and the curable resin after light irradiation. The absorption peak height (Y) at 1640 to 1620 cm ^-1 from the base line in the FT-IR measurement chart of the layer (cured resin layer 6) can be calculated by substituting into the following equation.
Reaction rate (%) = [(XY) / X] × 100

  In the step B, the first light having a peak in the wavelength range of 360 to 430 nm is irradiated on the curable resin layer 2 to cause a site of the curable resin layer 2 where oxygen inhibition occurs, specifically, the curable resin layer 2 It is preferable to irradiate the surface with the first light having a peak in a wavelength range of 360 to 430 nm and the second light having a peak in a wavelength range of 200 to 345 nm.

In step B, light is irradiated such that the integrated light amount of the first light having a peak in the wavelength range of 360 to 430 nm is larger than the integrated light amount of the second light having a peak in the wavelength range of 200 to 345 nm. Is preferred. Thereby, the adhesive performance at the time of temporary curing can be further improved. As an example, the integrated light amount of the first light having a peak in the wavelength range of 360 to 430 nm is in the range of 2000 to 5000 mJ / cm ² , and the integrated light amount of the second light having the peak in the wavelength range of 200 to 345 nm is It is preferably in the range of 20 mJ / cm ² or more and less than 1000 mJ / cm ² . In the step B, it is preferable to irradiate, for example, light having an emission wavelength of 365 ± 5 nm as illuminance of 100 to 500 mW / cm ² as the first light having a peak in the wavelength range of 360 to 430 nm. In the step B, it is preferable to irradiate, for example, light having an emission wavelength of 280 ± 5 nm as the second light having a peak in the wavelength range of 200 to 345 nm under an illuminance of 10 to 100 mW / cm ² . As the UV-LED used in the process B, for example, an LED having an emission peak wavelength in the range of 360 to 430 nm (for example, an emission wavelength of 365 ± 5 nm) and an emission wavelength peak wavelength of 200 to 345 nm (for example, an emission wavelength of 280 ± 5 nm).

  In the step B, the first light having a peak in the wavelength range of 360 to 430 nm may be irradiated simultaneously with the second light having a peak in the wavelength range of 200 to 345 nm. In the step B, after irradiating the first light having a peak in the wavelength range of 360 to 430 nm, the second light having the peak in the wavelength range of 200 to 345 nm may be irradiated. In the step B, after irradiating the second light having a peak in the wavelength range of 200 to 345 nm, the first light having the peak in the wavelength range of 360 to 430 nm may be irradiated.

  In the present manufacturing method, it is preferable to prevent dripping or deformation of the temporarily cured layer 5 during the laminating operation in Step C described below. For example, in the step B, before the curable resin layer 2 is irradiated with the first light having a peak in a wavelength range of 360 to 430 nm and the second light having a peak in a wavelength range of 200 to 345 nm, the curable resin layer 2 is cured. Light irradiation is preferably performed so that the viscosity of the resin layer 2 is 20 Pa · S or more (cone plate rheometer, 25 ° C., cone and plate C35 / 2, rotation speed 10 rpm).

<Step C>
In step C, for example, as shown in FIG. 4, the front plate 4 and the image display member 1 are bonded together with the temporary curing layer 5 interposed therebetween. For example, in step C, the front plate 4 is attached to the image display member 1 from the temporary cured layer 5 side. Lamination can be performed, for example, by applying pressure at 10 to 80 ° C. using a known pressure bonding apparatus.

  The front plate 4 only needs to have a light transmission property so that an image formed on the image display member 2 can be visually recognized. For example, a plate made of glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, or the like is used. And sheet-like materials. These materials may be subjected to a hard coat treatment, an antireflection treatment, or the like on one or both surfaces. Physical properties such as the thickness and elastic modulus of the front plate 4 can be appropriately determined according to the purpose of use. Further, the front plate 4 may be a laminate of various sheets or film materials such as a touch panel module.

  A light-shielding layer 3 may be provided on a peripheral portion of the front plate 4 to improve image contrast. The light-shielding layer 3 can be formed by, for example, applying a paint colored black or the like by a screen printing method, and drying and curing. The thickness of the light shielding layer 3 is usually 5 to 100 μm.

<Step D>
In step D, for example, light is applied to the temporary cured layer 5 shown in FIG. 5 through the front plate 4 to form a cured resin layer 6 as shown in FIG. The reason why the temporary curing layer 5 is fully cured in the step D is to sufficiently cure the temporary curing layer 5 and bond and laminate the image display member 1 and the front plate 4. By performing step D, as shown in FIG. 6, an image display device 7 including the image display member 1, the cured resin layer 6, and the front plate 4 in this order is obtained.

The main curing (light irradiation) in the step D is preferably performed so that the reaction rate of the cured resin layer 6 becomes 90% or more, and more preferably 97% or more. There are no particular restrictions on the type of light source, output, illuminance, integrated light amount, and the like when performing the main curing, and known photoradical polymerization process conditions for (meth) acrylate by ultraviolet irradiation can be employed. For example, ultraviolet irradiation, ultraviolet ray irradiation device (a metal halide lamp, high pressure mercury lamp, UV-LED, etc.) using, it is preferable to carry out at an intensity 50~300mW / cm ^2, the integrated quantity of light 1000~6000mJ / cm ² conditions. In particular, in the process D, it is preferable to irradiate the first light having a peak in the wavelength range of 360 to 430 nm using a UV-LED from the demand for the long life performance of the ultraviolet irradiation device as described above.

  In the step D, if necessary, the temporary curing layer 5 may be fully cured by irradiating the temporary curing layer 5 between the light shielding layer 3 of the front plate 4 and the image display member 1 with light. .

  The cured resin layer 6 in the image display device 7 obtained by the present manufacturing method preferably has a transmittance in the visible light region of 90% or more. By satisfying such a range, the visibility of the image formed on the image display member 1 can be further improved. The refractive index of the cured resin layer 6 is preferably substantially equal to the refractive index of the image display member 1 or the front plate 4. The refractive index of the cured resin layer 6 is preferably, for example, not less than 1.45 and not more than 1.55. Thereby, the brightness and contrast of the image light from the image display member 1 can be increased, and the visibility can be improved. The thickness of the cured resin layer 6 can be, for example, about 25 to 200 μm.

  According to the present production method as described above, the adhesive performance at the time of temporary curing can be improved.

  In step A, instead of applying the photocurable resin composition to the surface of the image display member 1, the photocurable resin composition is applied to the surface of the front plate 4 on which the light shielding layer 3 is formed. May be. Further, a front plate having no light-shielding layer 3 may be used as the front plate.

  Hereinafter, embodiments of the present technology will be described. Note that the present technology is not limited to these embodiments.

<Preparation of photocurable resin composition>
The components were uniformly mixed at the blending amounts (parts by mass) shown in Table 1 to prepare a photocurable resin composition.

The abbreviations in Table 1 are the following compounds.
Urethane acrylate oligomer: number average molecular weight 20,000
CN9014: urethane acrylate oligomer, Hartoid 7927 manufactured by Sartomer Co., Ltd .: 4HBA: 4-hydroxybutyl acrylate manufactured by Hitachi Chemical Co., Ltd., ISTA: isostearyl acrylate manufactured by BASF, Miramer M210 manufactured by Osaka Organic Chemical Co., Ltd .: neopentyl glycol diacrylate hydroxypivalate, MIWON PETIA: pentaerythritol (tri / tetra) acrylate NOA: n-octyl acrylate IDA: isodecyl acrylate IBXA: isobornyl acrylate FA-512M: dicyclopentenyloxyethyl methacrylate LA: lauryl acrylate M105: terpene resin, product Name: Clearon M105, GI-1000 manufactured by Yashara Chemical Co., Ltd .: Hydrogenated polybutadiene at both ends hydroxyl, Japan Soda GI-3000: Hydrogenated polybutadiene at both ends, terpene resin manufactured by Nippon Soda: Number average molecular weight 800
TPO: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, product name: LUCIRIN TPO, Irg184D from BASF: 1-hydroxy-cyclohexyl-phenyl-ketone, product name: Irgacure 184, MBF from BASF: phenylglyoxyl Methyl acid, product name: IRGACURE MBF, TZT manufactured by BASF: Product name: Esacure TZT, manufactured by Lamberti

[Example 1]
<Preparation of test sample using resin A>
As shown in FIG. 7A, a photo-curable resin composition 12 was applied from a slit nozzle 11 to a thickness of 33 μm from one end to the other end of the surface of the PET film 10 (thickness: 130 mm). Thereafter, the applied photocurable resin composition 12 was irradiated with light having a peak at a wavelength of 365 nm from the UV-LED 13 so that the integrated light amount became 500 mJ / cm ² . This light irradiation is performed in order to suppress liquid dripping of the applied photocurable resin composition. Thus, a first curable resin layer 14A was formed. Next, as shown in FIG. 7 (B), after applying the photocurable resin composition 12 from the slit nozzle 11 to a thickness of 33 μm on the curable resin layer 14A, the applied photocurable resin composition The second curable resin layer 14B was formed by irradiating the object 12 with light having a peak at a wavelength of 365 nm from the UV-LED 13 so that the integrated light amount became 500 mJ / cm ² . This light irradiation is also performed in order to suppress liquid dripping of the applied photocurable resin composition. Next, as shown in FIG. 7C, a photo-curable resin composition 12 is applied on the curable resin layer 14B from the slit nozzle 11 so as to have a thickness of 33 μm, and then the applied photo-curable resin composition By irradiating the object 12 with light having a peak at a wavelength of 365 nm from the UV-LED 13 so that the integrated light amount becomes 500 mJ / cm ² , a third curable resin layer 14C was formed. This light irradiation is also performed in order to suppress liquid dripping of the applied photocurable resin composition. Thus, a laminate in which the curable resin layer 14 having a thickness of about 100 μm was formed on the PET film 10 was obtained.

As shown in FIG. 7 (D), a UV-LED (manufactured by CCS, a plurality of LEDs having an emission wavelength of 365 nm, and a plurality of LEDs having an emission wavelength of 280 nm are provided on the curable resin layer 14 of the laminate. device with bets from irradiation range 80 mm × 80 mm), and a light having a peak wavelength 365nm of 200 mW / cm ² intensity as integrated light quantity is 5000 mJ / cm ^2, so that the integrated light quantity is 20 mJ / cm ² Light having a peak at a wavelength of 280 nm with an intensity of 20 mW / cm ² was irradiated. Thus, a laminate in which the temporary cured layer 15 was formed on the PET film 10 was obtained. The curing rate of the temporary cured layer 15 was about 80 to 90% when the height of the absorption peak at 1640 to 1620 cm ^-1 from the baseline in the FT-IR measurement chart was used as an index.

  As shown in FIG. 7E, the laminate was cut so as to have a width of 25 mm. As shown in FIG. 7F, the cut laminate was attached to a slide glass 16 (width 25 mm, thickness 1 mm). As shown in FIG. 7G, pressure was applied from the side of the laminate using a 2 kg load roller 17. As a result, the test sample 18 shown in FIG. 7H, that is, the test sample in which the PET film 10 and the slide glass 16 are bonded via the temporary hardened layer 15 (10 mm × 25 mm, thickness 0.1 mm). 18 was obtained.

<Measurement of shear strength of temporary hardened layer>
The shear strength of the temporary cured layer 15 in the test sample 18 was measured by the method shown in FIG. Specifically, the PET film 10 located on the lower side of the test sample 18 is fixed with a jig 19 using a table-top precision universal testing machine (manufactured by Shimadzu Corporation, Autograph), and the slide glass located on the upper side is fixed. The shear strength of the temporary hardened layer 15 when 16 was peeled off through the jig 20 in the vertical direction at a speed of 5 mm / min was measured. The results are shown in FIG.

[Examples 2 to 6, Comparative Examples 1 and 2]
A test sample was prepared in the same manner as in Example 1 except that the integrated light amount of light applied to the curable resin layer 14 of the laminate was as shown in the following table, and a temporary cured layer in the test sample was prepared. Was measured for shear strength. The results are shown in FIG.

[Example 7, Comparative Examples 3 to 5]
Using a resin B, a test sample was prepared in the same manner as in Example 1 except that the integrated light amount of light applied to the curable resin layer 14 of the laminate was as shown in the following table. The shear strength of the temporary hardened layer in the sample for use was measured. The results are shown in FIG.

[Example 8, Comparative Examples 6 to 8]
A test sample was prepared in the same manner as in Example 1 except that the integrated light amount of light applied to the curable resin layer 14 of the laminate was as shown in the following table using the resin C, and a test sample was prepared. The shear strength of the temporary hardened layer in the sample for use was measured. The results are shown in FIG.

[Example 9, Comparative Examples 9 to 11]
Using a resin D, a test sample was prepared in the same manner as in Example 1 except that the integrated light amount of light applied to the curable resin layer 14 of the laminate was set as shown in the following table. The shear strength of the temporary hardened layer in the sample for use was measured. In Comparative Example 10, only light having a peak at a wavelength of 365 nm with an intensity of 600 mW / cm ² was irradiated from the UV-LED so that the integrated light amount became 6000 mJ / cm ² . The results are shown in FIG.

[Example 10, Comparative Example 12]
Using a resin E, a test sample was prepared in the same manner as in Example 1 except that the integrated light amount of light applied to the curable resin layer 14 of the laminate was as shown in the following table. The shear strength of the temporary hardened layer in the sample for use was measured. The results are shown in FIG.

  From the results of Examples 1 to 10 and Comparative Examples 1 to 12, the light irradiated in the step of irradiating the curable resin layer with light from the UV-LED to form the temporary cured layer peaks in the wavelength range of 360 to 430 nm. And the second light having a peak in the wavelength range of 200 to 345 nm, the shear strength of the temporary cured layer is good, that is, the adhesive performance at the time of temporary curing is good. I found it. Further, from the results of Example 9 and Comparative Example 11, it was found that in Example 9, the adhesive performance at the time of temporary curing equal to or more than that at the time of irradiation with a metal halide lamp could be realized. Furthermore, from the results of Examples 1 to 10, it was found that the tendency of the improvement of the adhesive performance at the time of temporary curing did not depend on the composition ratio of the photocurable resin composition.

From the results of Examples 1 to 6, when the resin A was used, in the step of irradiating the curable resin layer with light from a UV-LED to form a temporary cured layer, a peak was in the wavelength range of 360 to 430 nm. first integrated quantity of light of the light is in a range of 2000~5000mJ / cm ^2, the second range integrated light quantity is less than 20 mJ / cm ² or more 1000 mJ / cm ² of light having a peak in a wavelength range of 200~345nm having It was found that the integrated light amount of the second light having a peak in the wavelength range of 200 to 345 nm was more preferably 500 mJ / cm ² or more and less than 1000 mJ / cm ² .

  In Example 8 and Comparative Examples 6 to 8, the resin C containing a photopolymerization initiator showing relatively mild reactivity was used, and the ratio of the plasticizer was large, so that the resin C was used in comparison with the case where another resin was used. Although there was a tendency that the shear strength at the time of temporary hardening was hardly developed, it was found that the shear strength of Example 8 was twice or more that of Comparative Examples 6 to 8.

  In Comparative Examples 1 to 12, the light irradiated in the step of forming a temporary cured layer by irradiating the curable resin layer with light from a UV-LED is only light having a peak in the wavelength range of 360 to 430 nm, or Since only light having a peak in the range of 200 to 345 nm was included, it was found that the adhesive performance at the time of temporary curing was not good.

In Comparative Example 4, although the integrated light amount of light having a peak in the wavelength range of 360 to 430 nm from the UV-LED was increased to 8000 mJ / cm ² , light having a peak in the wavelength range of 200 to 345 nm was not irradiated. It was found that the shear strength was extremely lower than that of Example 7. Further, it was found that Comparative Example 5 in which only light having a peak in the wavelength range of 200 to 345 nm was irradiated, had a significantly lower shear strength than Example 7. From these results, in consideration of the curability of the deep part of the curable resin layer, in the step of forming the temporary cured layer, light having a peak in the wavelength range of 360 to 430 nm and having a peak in the wavelength range of 200 to 345 nm It turns out that it is essential to use light together.

In Comparative Example 10, the illuminance of light having a peak in the wavelength range of 360 to 430 nm from the UV-LED was increased to 600 mW / cm ² and the integrated light amount was increased to 6000 mJ / cm ² , but the wavelength was 200 to 345 nm. It was found that the measurement result of the shear strength was inferior to that of Example 9 because no light having a peak in the range was irradiated.

<Measurement of shear strength of cured resin layer>
[Example 9-1]
Against temporary curing layer of a test sample in Example 9, using a conveyor with a metal halide lamp (USIO Co.), integrated light quantity was irradiated with light of 200 mW / cm ² intensity so that the 5000 mJ / cm ^2. As a result, the temporarily cured layer was completely cured to form a cured resin layer. The cure rate of the cured resin layer was 97%. The shear strength of this cured resin layer was measured by the same method as the above-described temporary cured layer. FIG. 14 shows the results. N1 to N4 in FIG. 14 represent four test samples, and represent the results of measuring the shear strength of the four test samples. The average (*) in FIG. 14 indicates the average value of the measurement results of the shear strength of N1 to N4.

[Example 9-2]
Light having a peak at a wavelength of 365 m with a wavelength of 200 mW / cm ² was irradiated to the temporary cured layer of the test sample in Example 9 using a UV-LED so that the integrated light amount became 5000 mJ / cm ² . . As a result, the temporarily cured layer was completely cured to form a cured resin layer. The cure rate of the cured resin layer was 97%. The shear strength of this cured resin layer was measured by the same method as the above-described temporary cured layer. FIG. 14 shows the results.

[Comparative Example 9-1]
Except for using the test sample in Comparative Example 9, the shear strength of the cured resin layer was measured in the same manner as in Example 9-1. FIG. 14 shows the results.

[Comparative Example 9-2]
Except for using the test sample in Comparative Example 9, the shear strength of the cured resin layer was measured in the same manner as in Example 9-2. FIG. 14 shows the results.

  From the results of Examples 9-1 and 9-2 and Comparative examples 9-1 and 9-2, it was found that the strengths of the cured resin layers were almost the same. This is presumably because the difference in physical adhesion (effect of oxygen inhibition) is noticeable during the temporary curing, while the difference in the chemical adhesion is further increased after the main curing.

Reference Signs List 1 image display member, 2 curable resin layer, 3 light shielding layer, 4 front plate, 5 temporary cured layer, 6 cured resin layer, 7 image display device, 10 PET film, 11 slit nozzle, 12 light curable resin composition, 13 UV-LED, 14 curable resin layer, 15 temporary cured layer, 16 slide glass, 17 load roller, 18 test sample, 19 jig, 20 jig

Claims (9)

Step A of forming a curable resin layer made of a photocurable resin composition on the surface of the front plate or the image display member,
A step B of irradiating the curable resin layer with light from a UV-LED to form a temporary cured layer;
A step C of bonding the front plate and the image display member through the temporary curing layer;
Irradiating the temporary cured layer with light through the front plate to form a cured resin layer;
The light irradiated in the step B includes first light having a peak in a wavelength range of 360 to 430 nm, and second light having a peak in a wavelength range of 200 to 345 nm.
In the step B, a method for manufacturing an image display device, wherein the first light is irradiated on the curable resin layer to irradiate the second light on a portion of the curable resin layer where oxygen inhibition occurs.   In the step B, the curable resin layer is irradiated with the first light and the second light so that the integrated light amount of the first light is larger than the integrated light amount of the second light. A method for manufacturing the image display device according to claim 1.   3. The method according to claim 1, wherein in the step B, the surface of the curable resin layer is irradiated with the first light and the second light. 4.   4. The method according to claim 1, wherein the thickness of the curable resin layer is 25 to 350 μm. 5. In the step B, in the range integrated light quantity of the first light is 2000~5000mJ / cm ^2, in the range integrated light quantity is less than 20 mJ / cm ² or more 1000 mJ / cm ² of the second light, wherein Item 5. The method for manufacturing an image display device according to any one of Items 1 to 4.   The photocurable resin composition according to any one of claims 1 to 5, wherein the photocurable resin composition contains a photoradical reactive component, a photopolymerization initiator, and at least one of a plasticizer and a tackifier. A method for manufacturing an image display device.   The method according to claim 6, wherein the photo-radical reactive component contains at least one of a (meth) acrylate oligomer and a (meth) acrylate monomer.   The photopolymerization initiator contains at least one of an alkylphenone-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, and an intramolecular hydrogen abstraction-type photopolymerization initiator. Item 8. The method for manufacturing an image display device according to item 6 or 7.   The photocurable resin composition contains 30 to 90% by mass of the photoradical reactive component in total, 2 to 6% by mass of the photopolymerization initiator, and at least one of the plasticizer and the tackifier. The method for producing an image display device according to any one of claims 6 to 8, comprising 5 to 58% by mass.