TW202025110A - Method for manufacturing image display device - Google Patents

Abstract

Provided is a method for manufacturing an image display device having a good adhesive performance in a temporary curing. The method for manufacturing an image display device related to the technology comprises: a process A of forming a curable resin layer (2) formed by a photocurable resin composition on a front plate (4) or a surface of an image display member (1); a process B of forming a temporary cured layer (5) by irradiating light from UV-LED to the curable resin layer (2); a process C of bonding the front plate (4) to the image display member (1) through the temporary cured layer (5); and a process D of irradiating light to the temporary cured layer (5) through the front plate (4) and forming a cured resin layer (6). The light irradiated in the process B includes a first light having a peak in a range of 360-430 nm of a wavelength, and a second light having a peak in a range of 200-345 nm of a wavelength. In a process B, the first light is irradiated to a curable resin layer (2) and then, the second light is irradiated to part of the curable resin layer (2) generating oxygen inhibition.

Description

Manufacturing method of image display device

This technology relates to a method of manufacturing an image display device.

Patent Document 1 describes a method for manufacturing a display device, which includes: a first irradiation step (pre-curing step), which irradiates light to an adhesive applied on at least one of a display panel and a substrate; and a bonding step After the first irradiation step, the display panel is bonded to the substrate; and the second irradiation step (formal curing step) is after the bonding step, and further irradiates the adhesive with light.

The hardening state of the top surface of the resin in the pre-hardening step is very important for maintaining alignment during bonding. Regarding the hardening state of the outermost surface of the resin, the greater the influence of oxygen barrier during pre-hardening, the lower the hardening rate, and correspondingly, the adhesive function also tends to decrease. Therefore, as the ultraviolet irradiation device, one having a wide wavelength range and high output such as a metal halide lamp or a high-pressure mercury lamp is preferable.

However, in recent years, based on the requirement of long-life performance of ultraviolet irradiation devices, there is a tendency that, for example, UV-LED (Ultraviolet Rays-Light Emitting Diode) with a peak in the wavelength range of 360-430 nm is widely used as a light source. . Since this type of UV-LED is used at a single wavelength, there is a risk that the adhesive performance during pre-curing may be reduced due to the influence of oxygen hindrance. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. WO2009/054168

[The problem to be solved by the invention]

This technology is proposed in view of the above-mentioned previous actual situation, and it provides a method for manufacturing an image display device with good adhesive performance during pre-curing. [Technical means to solve the problem]

The manufacturing method of the image display device of the present technology has: Step A, which is to form a curable resin layer containing a photocurable resin composition on the surface of the front panel or the image display member; Step B, which is derived from UV-LED Light is irradiated to the curable resin layer to form a pre-cured layer; step C is to bond the front panel and the image display member through the pre-cured layer; and step D is to perform the pre-cured layer through the front panel Light is irradiated to form a hardened resin layer; the light irradiated in step B includes the first light having a peak in the range of 360-430 nm in wavelength and the second light having a peak in the range of 200-345 nm in wavelength, in step B In this, the second light is irradiated to the portion of the curable resin layer that is irradiated with the first light to the curable resin layer to cause oxygen inhibition. [Effects of Invention]

According to this technology, the adhesive performance at the time of pre-curing can be improved.

The detailed content of the manufacturing method of the image display device of the present technology (hereinafter also referred to as the manufacturing method) will be described below. In the following description, the term (meth)acrylate includes both acrylate and methacrylate. In addition, the term "(meth)acrylic acid group" includes both acrylic acid group and methacrylic acid group.

The manufacturing method has: step A, which is to form a curable resin layer containing a photocurable resin composition on the surface of the front panel or image display member; step B, which is to irradiate light from the UV-LED to the curable resin layer The pre-hardened layer is formed; step C is to bond the front panel and the image display member through the pre-hardened layer; and step D is to irradiate the pre-hardened layer with light through the front panel to form a hardened resin layer. The light irradiated in step B includes the first light having a peak in the wavelength range of 360-430 nm, and the second light having a peak in the wavelength range of 200-345 nm. In step B, the second light is irradiated to the portion of the curable resin layer where the curable resin layer is irradiated with the first light to cause oxygen inhibition. The first light having a peak in the wavelength range of 360-430 nm has a smaller energy than the second light having a peak in the wavelength range of 200-345 nm, and can reach the depth of the curable resin layer. On the other hand, the second light with a peak in the wavelength range of 200-345 nm has greater energy than the first light with a peak in the wavelength range of 360-430 nm, and cannot reach the depth of the curable resin layer, but only reaches the curing The surface part of the resin layer. As the light irradiated in step B, the first light having a peak in the range of wavelength 360-430 nm and the second light having a peak in the range of 200-345 nm are used together to irradiate only the wavelength 360 to Compared with the first light with a peak in the range of 430 nm, the influence of oxygen barrier can be reduced, and the adhesion performance during pre-curing can be improved.

<Step A> In step A of the manufacturing method, as shown in FIG. 1, a curable resin layer 2 containing a photocurable resin composition is formed on the surface of the image display member 1. For example, in step A, it is preferable to form the curable resin layer 2 by coating the entire surface of the image display member 1 so that the photocurable resin composition becomes flat. The thickness of the curable resin layer 2 is preferably, for example, a thickness that can eliminate the step difference formed between the light-shielding layer 3 and the light-shielding layer forming side surface of the front panel 4 described later, and can be set to 2.5-40 of the thickness of the light-shielding layer 4 Times, it may be 2.5 to 12.5 times, or 2.5 to 4 times. As an example, the thickness of the curable resin layer 2 may be 25 to 350 μm, or 50 to 150 μm. There are no particular restrictions on the number of times of application of the photocurable resin composition as long as it is carried out so as to obtain the desired resin thickness, and it may be one time or multiple times.

The image display member 1 is, for example, an image display panel in which a polarizing plate is formed on the visible side surface of an image display unit. As the image display unit, for example, a liquid crystal unit or an organic EL (Electroluminescence) unit can be cited. As a liquid crystal cell, a reflective liquid crystal cell, a transmissive liquid crystal cell, etc. are mentioned, for example. 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 so-called touch panel refers to an image display and input panel that combines a display element such as a liquid crystal display panel and a position input device such as a touch panel.

The photocurable resin composition for forming the curable resin layer 2 contains, for example, at least one of a photoradical reactive component, a plasticizer, and an adhesion imparting component, and a photopolymerization initiator. The photocurable resin composition may further contain other components within a range that does not impair the effect of this technology.

＜Light radical reactive components＞ The photoradical reactive component contains at least one of (meth)acrylate oligomer and (meth)acrylate monomer. The (meth)acrylate oligomer has polyisoprene, polyurethane, polybutadiene, etc. in the skeleton, and preferably has a polyurethane in the skeleton ((methyl ) Acrylic urethane oligomer). The (meth)acrylate oligomer preferably has 1 to 4 (meth)acrylic groups, and more preferably has 2 to 3 (meth)acrylic groups. As a commercially available product of (meth)acrylate urethane oligomer, for example, CN9014 (manufactured by Sadovan), EBECRYL 230, EBECRYL 270 (above, manufactured by Daicel-Allnex), etc. can be used.

The (meth)acrylate monomer is used as a reactive diluent for imparting sufficient reactivity and coating properties to the photocurable resin composition. The (meth)acrylate monomer may be a monofunctional (meth)acrylate, a bifunctional (meth)acrylate, or a multifunctional (meth)acrylate. For example, from the viewpoint of compatibility with other components, the (meth)acrylate monomer preferably includes a (meth)acrylate monomer having a hydroxyl group (for example, 4-hydroxybutyl acrylate), and a cyclic Structure of (meth)acrylate monomers (such as isopropyl acrylate, dicyclopentenyloxyethyl methacrylate), (meth)acrylic acid C5-20 alkyl ester monomers (such as acrylic acid N-octyl ester, isodecyl acrylate, lauryl acrylate, isostearyl acrylate), and multifunctional (meth)acrylate monomers (such as pentaerythritol (tri/tetra) acrylate, neopentyl glycol hydroxypivalate) Diacrylate) and so on.

The total content of the (meth)acrylate oligomer and the (meth)acrylate monomer in the photocurable resin composition may be 95% by mass or less, or 90% by mass or less. In addition, the total content of the (meth)acrylate oligomer and the (meth)acrylate monomer in the photocurable resin composition may be 20% by mass or more, or 30% by mass or more, or It is 35% by mass or more. (Meth)acrylate oligomer and/or (meth)acrylate monomer may be used individually by 1 type, and may use 2 or more types together. When two or more types of (meth)acrylate oligomers and/or (meth)acrylate monomers are used in combination, it is preferable that the total content thereof is within the above-mentioned range.

＜Photopolymerization initiator＞ As the photopolymerization initiator, a known photoradical polymerization initiator can be used. As the photopolymerization initiator, an alkyl ketone-based photopolymerization initiator, an oxyphosphine oxide-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, and an intramolecular hydrogen abstraction type photopolymerization initiator can be used.剂 etc. As specific examples, 2,4,6-trimethylbenzyldiphenylphosphine oxide, 1-hydroxy-cyclohexyl-phenyl-ketone, methyl phenylglyoxylate, and the like can be cited. As examples of commercially available products, LUCIRIN TPO, Irgacure 184, IRGACURE MBF (the above are manufactured by BASF Corporation), Esacure TZT (manufactured by Lamberti Corporation), and the like can be cited.

The total content of the photopolymerization initiator in the photocurable resin composition may be 10% by mass or less, 8% by mass or less, or 6% by mass or less. In addition, 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. A photoinitiator may be used individually by 1 type, and may use 2 or more types together. When two or more types of photopolymerization initiators are used in combination, it is preferable that the total content thereof is within the above-mentioned range.

＜Plasticizer and Adhesive Agent＞ The plasticizer and the adhesion imparting agent do not substantially react with the (meth)acrylate oligomer and the (meth)acrylate monomer due to light irradiation. Examples of the adhesion-imparting component include solid adhesion-imparting agents and liquid oil components. Examples of the solid adhesion imparting agent 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; hydrogenated terpene resins. Examples of the liquid oil component include polybutadiene-based oils, polyisoprene-based oils, and the like. As a commercially available product of a plasticizer and an adhesive agent, Clearon M105 (manufactured by Yashara Chemical Co., Ltd.), GI-1000, GI-3000 (manufactured by Soda Corporation), etc. are mentioned, for example.

When the photocurable resin composition contains at least one of a plasticizer and an adhesive imparting agent, the total content of the plasticizer and adhesive imparting agent in the photocurable resin composition may be 70% by mass or less, It may be 65% by mass or less, 60% by mass or less, or 58% by mass or less. In addition, the total content of the plasticizer and the adhesion imparting agent in the photocurable resin composition can be 0.5% by mass or more, 2% by mass or more, 4% by mass or more, or 5% by mass. % Or more, but also 7 mass% or more. A plasticizer and/or an adhesion-imparting agent may be used individually by 1 type, and may use 2 or more types together. When two or more plasticizers and/or adhesion-imparting agents are used in combination, it is preferable that the total content of the plasticizer and/or adhesion-imparting agent is within the above range.

＜Other ingredients＞ The photocurable resin composition may contain, in addition to the above-mentioned components, for example, polymer components (other than the above-mentioned photoradical reactive components, plasticizers, and adhesion-imparting agents) within a range that does not impair the effects of this technology. Polymer components), antioxidants, light stabilizers, silane coupling agents, etc. As the polymer component, for example, Hitaloid 7927 (manufactured by Hitachi Chemical Co., Ltd.) can be used. The Hitaloid 7927 is a UV curable resin containing a polymer as the main component and an acrylic monomer as a reactive diluent, and the polymer as the main component functions as an adhesion imparting agent. In the present invention, when the photocurable resin composition contains Hitaloid 7927, the content of Hitaloid 7927 in the photocurable resin composition is calculated as the content of the aforementioned adhesive imparting agent. As the antioxidant, for example, a hindered phenol-based antioxidant can be used. As commercial products of antioxidants, for example, IRGANOX 1520L and IRGANOX 1010 (the above are made by BASF) can be used. As the light stabilizer, for example, a hindered amine-based light stabilizer can be used. As a commercially available product of the light stabilizer, for example, Adekastab LA-52 (manufactured by ADEKA) can be used. As the silane coupling agent, for example, 3-propenoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethylsilane, and 3-mercaptopropyltrimethoxysilane can be used. As commercially available products of the silane coupling agent, for example, KBM5103, KBM503, and KBM803 (the above are manufactured by Shin-Etsu Silicone Co., Ltd.) can be used.

<Step B> In step B of the manufacturing method, light is irradiated from the UV-LED to the curable resin layer 2 as shown in FIG. 2 to form the pre-cured layer 5 as shown in FIG. 3. In step B, the curable resin layer 2 formed in step A is irradiated with the first light having a peak in the wavelength range of 360-430 nm and the second light having a peak in the wavelength range of 200-345 nm.

The light irradiation in step B is preferably carried out in a way that the reaction rate of the pre-hardened layer 5 reaches 10 to 90%, more preferably is carried out in a way to reach 40 to 90%, and more preferably to reach 70 to 90%. Way to proceed. The so-called reaction rate is defined as the ratio (consumption ratio) of the amount of (meth)acrylic acid groups present after light irradiation to the amount of (meth)acrylic acid groups present in the curable resin layer before light irradiation Numerical value. The larger the value of the reaction rate, the better the hardening. Specifically, the reaction rate can be measured by FT-IR (fourier transform infrared radiation, Fourier transform infrared spectroscopy) of the curable resin layer before irradiating light. The absorption of 1640-1620 cm ^-1 from the reference line in the figure The peak height (X) and the absorption peak height (Y) of 1640～1620 cm ^-1 from the reference line in the FT-IR measurement of the curable resin layer (cured resin layer 6) after light irradiation are substituted into the following Calculated from the formula. Response rate (%)=[(X－Y)/X]×100

In step B, it is preferable to irradiate the curable resin layer 2 with the first light having a peak in the wavelength range of 360 to 430 nm to the curable resin layer 2, specifically the curable resin The surface of the layer 2 is irradiated with the first light having a peak in the wavelength range of 360-430 nm and the second light having a peak in the wavelength range of 200-345 nm.

In step B, it is preferable to irradiate the light in such a way that the cumulative light quantity of the first light having a peak in the wavelength range of 360-430 nm is greater than the cumulative light quantity of the second light having a peak in the wavelength range of 200-345 nm. Thereby, the adhesive performance during pre-curing can be improved. As an example, it is preferable that the cumulative light quantity of the first light having a peak in the wavelength range of 360-430 nm is in the range of 2000-5000 mJ/cm ² and the cumulative light quantity of the second light having a peak in the wavelength range of 200-345 nm The amount of light is more than 20 mJ/cm ² and less than 1000 mJ/cm ² . In step B, as the first light having a peak in the wavelength range of 360-430 nm, for example, it is preferable to irradiate light with an emission wavelength of 365±5 nm under the condition of an illuminance of 100-500 mW/cm ² . Furthermore, in step B, as the second light having a peak in the wavelength range of 200 to 345 nm, it is preferable to irradiate light with an emission wavelength of 280 ± 5 nm under the condition of an illuminance of 10 to 100 mW/cm ² . As the UV-LED used in step 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 can be used (As an example, the luminescence wavelength is 280±5 nm) LED device.

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

In this manufacturing method, it is preferable to perform pretreatment to avoid dripping or deformation of the pre-hardened layer 5 during the bonding operation of step C described later. For example, it is preferable that in step B, before irradiating the curable resin layer 2 with the first light having a peak in the wavelength range of 360-430 nm and the second light having a peak in the wavelength range of 200-345 nm, Light irradiation is performed so that the viscosity of the curable resin layer 2 reaches 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 panel 4 and the image display member 1 are bonded via the pre-hardened layer 5. For example, in step C, the front panel 4 is attached to the image display member 1 from the side of the pre-hardened layer 5. The bonding can be performed, for example, by using a known crimping device and applying pressure at 10 to 80°C.

The front panel 4 only needs to have translucency that allows the image formed on the image display member 2 to be visually recognized. Examples include glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, and poly Plate-like or sheet-like materials such as carbonate. For these materials, hard coating treatment, anti-reflection treatment, etc. can also be implemented on one or both sides. Physical properties such as the thickness or elastic modulus of the front panel 4 can be appropriately determined according to the purpose of use. In addition, the front panel 4 may also be formed by laminating various sheets or film materials like touch panel modules.

A light-shielding layer 3 can also be provided on the periphery of the front panel 4 to improve the contrast of the image. The light-shielding layer 3 can be formed by applying a paint colored black or the like by a screen printing method or the like, and drying and hardening. The thickness of the light shielding layer 3 is usually 5-100 μm.

<Step D> In step D, for example, the pre-hardened layer 5 shown in FIG. 5 is irradiated with light via the front panel 4 to form the hardened resin layer 6 shown in FIG. 6. The main purpose of hardening the pre-hardened layer 5 in step D is to fully harden the pre-hardened layer 5, and to laminate the image display member 1 and the front panel 4 together. By performing step D, an image display device 7 including an image display member 1, a cured resin layer 6, and a front panel 4 in this order can be obtained as shown in FIG.

The formal hardening (light irradiation) in step D is preferably carried out so that the reaction rate of the hardened resin layer 6 reaches 90% or more, and more preferably it is 97% or more. The type, output, illuminance, accumulated light amount, etc. of the light source during the formal curing are not particularly limited, and the process conditions of the photo-radical polymerization of (meth)acrylate by the well-known ultraviolet irradiation can be used. For example, the ultraviolet irradiation is preferably performed using an ultraviolet irradiation machine (metal halide lamp, high-pressure mercury lamp, UV-LED, etc.) under the conditions of an illuminance of 50 to 300 mW/cm ² and a cumulative light amount of 1000 to 6000 mJ/cm ² . Especially in step D, based on the requirement of long life performance of the ultraviolet irradiation device as described above, it is preferable to use UV-LED to irradiate the first light with a peak in the wavelength range of 360-430 nm.

Furthermore, in step D, if necessary, the pre-hardened layer 5 can be formally hardened by irradiating the pre-hardened layer 5 between the light shielding layer 3 of the front panel 4 and the image display member 1 with light.

The cured resin layer 6 in the image display device 7 obtained by the manufacturing method preferably has a transmittance of 90% or more in the visible light region. By satisfying such a range, the visibility of the image formed on the image display member 1 can be improved. The refractive index of the cured resin layer 6 is preferably approximately the same as the refractive index of the image display member 1 or the front panel 4. The refractive index of the cured resin layer 6 is preferably 1.45 or more and 1.55 or less, for example. Thereby, the brightness or contrast of the image light from the image display member 1 can be improved, and the visibility can be improved. The thickness of the cured resin layer 6 can be set to about 25 to 200 μm, for example.

According to the present manufacturing method described above, the adhesive performance during precuring can be improved.

Furthermore, in step A, instead of coating the photocurable resin composition on the surface of the image display member 1, and coating the photocurable resin composition on the surface of the front panel 4 on the side where the light shielding layer 3 is formed Things. In addition, as the front panel, a front panel that does not have the light shielding layer 3 can also be used. [Example]

Hereinafter, embodiments of the present technology will be described. Furthermore, the present technology is not limited by these embodiments.

<Preparation of photocurable resin composition> Each component was uniformly mixed in the compounding amount (parts by mass) shown in Table 1 to prepare a photocurable resin composition.

[Table 1] Resin A Resin B Resin C Resin D Resin E Acrylic Urethane Oligomer 5.80 5.66 24.51 0 0 CN9014 3.87 3.78 0 0 0 Hitaloid7927 0 0 0 7.50 57.85 4HBA 11.60 11.33 3.23 15.94 14.22 ISTA 54.14 53.80 1.94 59.07 0 Miramer M210 0.10 0.09 0 0 0 PETIA 0 0 0 0.94 0 NOA 15.47 15.10 0 0 6.64 IDA 0 0 0 11.25 10.43 IBXA 0 0 11.61 0 0 FA-512M 0 0 6.45 0 0 LA 0 0 3.87 0 5.69 M105 0 0 9.68 0 0 GI-1000 0 0 22.58 0 0 GI-3000 0 0 12.90 0 0 Terpene resin 5.80 4.72 0 0 0 TPO 0.10 0.09 0.19 0.56 0.28 Irg184D 0 0 2.58 0 0 MBF 2.90 2.83 0 4.69 4.74 TZT 0 2.36 0 0 0

The abbreviations in Table 1 refer to the following compounds. Acrylic urethane oligomer: number average molecular weight 20000 CN9014: Acrylic urethane oligomer, manufactured by Sadoven Company Hitaloid7927: manufactured by Hitachi Chemical Co., Ltd. 4HBA: 4-hydroxybutyl acrylate, manufactured by BASF ISTA: Isostearyl acrylate, manufactured by Osaka Organic Chemical Co., Ltd. Miramer M210: hydroxypivalate neopentyl glycol diacrylate, manufactured by MIWON PETIA: pentaerythritol (tri/tetra) acrylate NOA: n-octyl acrylate IDA: Isodecyl acrylate IBXA: Isopropyl acrylate FA-512M: Dicyclopentenoxyethyl methacrylate LA: Lauryl Acrylate M105: Terpene resin, product name: Clearon M105, manufactured by Anyuan Chemical Company GI-1000: Hydrogenated polybutadiene with both terminal hydroxyl groups, manufactured by Soda Japan GI-3000: Hydrogenated polybutadiene with two terminal hydroxyl groups, manufactured by Soda Japan Terpene resin: number average molecular weight 800 TPO: 2,4,6-trimethylbenzyl diphenyl phosphine oxide, product name: LUCIRIN TPO, manufactured by BASF Irg184D: 1-hydroxy-cyclohexyl-phenyl-ketone, product name: Irgacure184, manufactured by BASF MBF: Methyl phenylglyoxylate, product name: IRGACURE MBF, manufactured by BASF TZT: Product name: Esacure TZT, manufactured by Lamberti

[Example 1] <Preparation of test sample using resin A> As shown in FIG. 7(A), from one end side of the surface of the PET film 10 (thickness 130 mm) to the other end side, from the slit nozzle 11 The photocurable resin composition 12 is applied to a thickness of 33 μm, and then the applied photocurable resin composition 12 is irradiated at a wavelength of 365 nm from the UV-LED 13 to a cumulative light amount of 500 mJ/cm ² Light with a peak. This light irradiation is performed to suppress dripping of the applied photocurable resin composition. This forms the first curable resin layer 14A. Then, as shown in FIG. 7(B), the photocurable resin composition 12 was applied from the slit nozzle 11 to a thickness of 33 μm on the curable resin layer 14A, and then the cumulative light amount reached 500 mJ/cm ² In this way, the applied photocurable resin composition 12 is irradiated with light having a peak at a wavelength of 365 nm from the UV-LED 13 to form the second curable resin layer 14B. The light irradiation is also performed to suppress dripping of the applied photocurable resin composition. Then, as shown in FIG. 7(C), the photocurable resin composition 12 was applied from the slit nozzle 11 to a thickness of 33 μm on the curable resin layer 14B, and then the cumulative light amount reached 500 mJ/cm ² In this way, the applied photocurable resin composition 12 is irradiated with light having a peak at a wavelength of 365 nm from the UV-LED 13 to form the third curable resin layer 14C. The light irradiation is also performed to suppress dripping of the applied photocurable resin composition. Thereby, a laminate in which the curable resin layer 14 having a thickness of about 100 μm is formed on the PET film 10 is obtained.

As shown in Fig. 7(D), the curable resin layer 14 of the laminate is made from UV-LED (manufactured by CCS, which has a plurality of LEDs with an emission wavelength of 365 nm and a plurality of LEDs with an emission wavelength of 280 nm. Device, irradiation range 80 mm×80 mm), irradiate light with a peak intensity of 200 mW/cm ² at a wavelength of 365 nm in a way that the cumulative light amount reaches 5000 mJ/cm ² , and the cumulative light amount reaches 20 mJ/cm ² The method irradiates light with a peak intensity of 20 mW/cm ² at a wavelength of 280 nm. In this way, a laminate in which the pre-cured layer 15 is formed on the PET film 10 is obtained. The hardening rate of the pre-hardened layer 15 is obtained by using the absorption peak height of 1640-1620 cm ^-1 from the reference line in the FT-IR measurement chart as an index, and the result is about 80-90%.

As shown in Figure 7(E), cut the laminate so that the width of the laminate is 25 mm. As shown in Fig. 7(F), the cut laminate is attached to a slide glass 16 (width 25 mm, thickness 1 mm). As shown in FIG. 7(G), a 2 kg load roller 17 is used to press the laminate from the side. Thereby, the test sample 18 shown in FIG. 7(H), that is, the PET film 10 and the glass slide 16 are separated by the pre-hardened layer 15 (10 mm×25 mm, thickness 0.1 mm) and the test sample bonded together is obtained 18.

＜Measurement of shear strength of pre-hardened layer＞ The shear strength of the pre-hardened layer 15 in the test sample 18 was measured by the method shown in FIG. 8. Specifically, using a desktop precision universal testing machine (manufactured by Shimadzu Corporation, auto-stereograph), the PET film 10 located on the lower side of the test sample 18 is fixed with a clamp 19, and the slide glass located on the upper side 16 was peeled off in the vertical direction at a speed of 5 mm/min through the clamp 20, and the shear strength of the pre-hardened layer 15 at this time was measured. The results are shown in Figure 9 and Table 2.

[Examples 2 to 6, Comparative Examples 1 and 2] The cumulative light intensity of the light irradiated to the curable resin layer 14 of the laminate is shown in the table below. Except that, a test sample was prepared in the same manner as in Example 1, and the shear of the pre-cured layer in the test sample was measured. Shear strength. The results are shown in Figure 9 and Table 2.

[Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Comparative example 2 Cumulative light quantity (mJ/cm ² ) UV-LED (365 nm) 5000 5000 5000 5000 5000 5000 5000 5300 Cumulative light quantity (mJ/cm ² ) UV-LED (280 nm) 20 60 100 200 500 1000 0 0 Shear strength (N) 152 180 178 211 226 194 89 113

[Example 7, Comparative Examples 3 to 5] The resin B is used, and the cumulative light quantity of the light irradiated to the curable resin layer 14 of the laminate is shown in the table below, except that the test sample is produced in the same manner as in Example 1, and the test sample is measured. Shear strength of the pre-hardened layer. The results are shown in Figure 10 and Table 3.

[table 3] Example 7 Comparative example 3 Comparative example 4 Comparative example 5 Cumulative light quantity (mJ/cm ² ) UV-LED (365 nm) 2000 2000 8000 0 Cumulative light quantity (mJ/cm ² ) UV-LED (280 nm) 200 0 0 200 Shear strength (N) 160 37 50 4

[Example 8, Comparative Examples 6-8] The resin C was used, and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate is shown in the table below. Except that the test samples were prepared in the same manner as in Example 1, the test samples were measured. Shear strength of the pre-hardened layer. The results are shown in Figure 11 and Table 4.

[Table 4] Example 8 Comparative example 6 Comparative example 7 Comparative example 8 Cumulative light quantity (mJ/cm ² ) UV-LED (365 nm) 2000 2000 2300 4000 Cumulative light quantity (m J/cm ² ) UV-LED (280 nm) 200 0 0 0 Shear strength (N) 5 2 2.4 2.5

[Example 9, Comparative Examples 9-11] The resin D was used, and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate is shown in the following table, except that the same method as Example 1 was used. Make test samples and measure the shear strength of the pre-hardened layer in the test samples. Furthermore, in Comparative Example 10, only light with an intensity of 600 mW/cm ² having a peak at a wavelength of 365 nm was irradiated from the UV-LED so that the cumulative light amount reached 6000 mJ/cm ² . The results are shown in Figure 12 and Table 5.

[table 5] Example 9 Comparative example 9 Comparative example 10 Comparative example 11 Cumulative light quantity (m JA:m ² ) UV-LED (365 nm) 2000 2000 0 0 Cumulative halo (rnJ/cm ² ) UV-LED (365 nm, high illuminance 600 mW/cm ² ) 0 0 6000 0 Cumulative light quantity (mJ/cm ² ) UV-LED (280 nm) 200 0 0 0 Cumulative light quantity (mJ/cm ² ) Metal halide lamp 0 0 0 4000 Shear strength (N) 220 139 175 216

[Example 10, Comparative Example 12] The resin E is used, and the cumulative light quantity of the light irradiated to the curable resin layer 14 of the laminate is shown in the following table, except that the test sample is produced in the same manner as in Example 1, and the test sample is measured. Shear strength of the pre-hardened layer. The results are shown in Figure 13 and Table 6.

[Table 6] Example 10 Comparative example 12 Cumulative light quantity (mJ/cm ² ) UV-LED (365 nm) 2900 2900 Cumulative light quantity (mJ/cm ² ) UV-LED (280 nm) 200 0 Shear strength (N) 143 33

From the results of Examples 1 to 10 and Comparative Examples 1 to 12, it can be seen that the light irradiated in the step of forming the pre-cured layer by irradiating light from the UV-LED to the curable resin layer is included in the wavelength range of 360-430 nm The first light with a peak and the second light with a peak in the wavelength range of 200-345 nm have good shear strength of the pre-hardened layer, that is, good adhesive performance during pre-hardening. In addition, from the results of Example 9 and Comparative Example 11, it can be seen that in Example 9, the adhesive performance at the time of pre-curing equal to or higher than that of the metal halide lamp irradiation can be achieved. Furthermore, it can be seen from the results of Examples 1 to 10 that the tendency of the adhesive performance to improve during the precuring does not depend on the composition ratio of the photocurable resin composition.

From the results of Examples 1 to 6, it can be seen that when resin A is used, in the step of irradiating light from the UV-LED to the curable resin layer to form a pre-cured layer, it is preferably in the range of 360-430 nm in wavelength The cumulative light intensity of the first light with a peak is in the range of 2000-5000 mJ/cm ² , and the cumulative light intensity of the second light with a peak in the wavelength range of 200-345 nm is 20 mJ/cm ² or more and less than 1000 mJ/ The range of cm ² is more preferably a range where the cumulative light intensity of the second light having a peak in the wavelength range of 200-345 nm is 500 mJ/cm ² or more and less than 1000 mJ/cm ² .

In Example 8 and Comparative Examples 6 to 8, it can be seen that since it contains a photopolymerization initiator that exhibits relatively stable reactivity and uses resin C with a higher ratio of plasticizers, it is comparable to the case of using other resins. There is a tendency that the shear strength is harder to appear than during the pre-hardening, but Example 8 exhibits more than twice the shear strength compared with Comparative Examples 6-8.

In Comparative Examples 1-12, it can be seen that the light irradiated in the step of forming the pre-cured layer by irradiating light from the UV-LED to the curable resin layer includes only light having a peak in the wavelength range of 360-430 nm, or The wavelength range of 200-345 nm has peak light, so the adhesive performance during pre-curing is not good.

In Comparative Example 4, it can be seen that although the cumulative amount of light from the UV-LED with a peak in the wavelength range of 360-430 nm is increased to 8000 mJ/cm ² , it is not irradiated in the wavelength range of 200-345 nm. The peak light, therefore, the shear strength is extremely low compared to Example 7. In addition, in Comparative Example 5 in which only light having a peak in the wavelength range of 200 to 345 nm was irradiated, it was found that the shear strength was extremely low compared to Example 7. It can be seen from these results that if the curability of the curable resin layer is considered, the step of forming the pre-cured layer must also be used for light with a peak in the wavelength range of 360 to 430 nm, and wavelengths of 200 to 345. The range of nm has a peak light.

In Comparative Example 10, it can be seen that although the illuminance of light with a peak in the wavelength range of 360-430 nm from the UV-LED is increased to 600 mW/cm ² , and the cumulative light quantity is increased to 6000 mJ/cm ² , The light with a peak in the wavelength range of 200-345 nm was not irradiated, so the measurement result of the shear strength was inferior to Example 9.

<Measurement of Shear Strength of Hardened Resin Layer> [Example 9-1] For the pre-hardened layer of the test sample in Example 9, a metal halide lamp with a conveyor (manufactured by USIO) was used to accumulate the amount of light The method reaches 5000 mJ/cm ² to irradiate light with an intensity of 200 mW/cm ² . Thereby, the pre-cured layer is completely cured to form a cured resin layer. The curing rate of the cured resin layer is 97%. The shear strength of the hardened resin layer was measured by the same method as the above-mentioned pre-hardened layer. The results are shown in Figure 14. Furthermore, N1 to N4 in Fig. 14 prepare 4 samples for each test, and show the measurement results of the shear strength of the 4 test samples. The average (*) in Fig. 14 represents the average value of the measurement results of the shear strength of N1 to N4.

[Example 9-2] For the pre-hardened layer of the test sample in Example 9, using UV-LED to achieve a cumulative light intensity of 5000 mJ/cm ² plane irradiation intensity 200 mW/cm ² at a wavelength of 365 nm Light with a peak. Thereby, the pre-cured layer is completely cured to form a cured resin layer. The curing rate of the cured resin layer is 97%. The shear strength of the hardened resin layer was measured by the same method as the above-mentioned pre-hardened layer. The results are shown in Figure 14.

[Comparative Example 9-1] Except for using the test sample in Comparative Example 9, the shear strength of the hardened resin layer was measured in the same manner as in Example 9-1. The results are shown in Figure 14.

[Comparative Example 9-2] Except for using the test sample in Comparative Example 9, the shear strength of the hardened resin layer was measured in the same manner as in Example 9-2. The results are shown in Figure 14.

From the results of Examples 9-1 and 9-2 and Comparative Examples 9-1 and 9-2, it can be seen that the strength of the cured resin layer is approximately the same. The reason for this is considered to be that the difference in physical adhesion (influence of oxygen hindrance) during the pre-hardening is significantly manifested, and the difference in chemical adhesion is further added after the actual hardening.

1: Image display component 2: Curable resin layer 3: shading layer 4: Front panel 5: Pre-hardened layer 6: Hardened resin layer 7: Image display device 10: PET film 11: slit nozzle 12: Light-curable resin composition 13: UV-LED 14: Curable resin layer 14A: The first curable resin layer 14B: The second curable resin layer 14C: The third curable resin layer 15: Pre-hardened layer 16: glass slide 17: Load roller 18: Test sample 19: Fixture 20: Fixture

1 is a cross-sectional view for explaining an example of the step of forming a curable resin layer containing a photocurable resin composition on the surface of an image display member. 2 is a cross-sectional view for explaining an example of a step of forming a pre-cured layer by irradiating light from a UV-LED to a curable resin layer. 3 is a cross-sectional view for explaining an example of a step of irradiating light from a UV-LED to a curable resin layer to form a pre-cured layer. 4 is a cross-sectional view for explaining an example of the step of bonding the front panel and the image display member through the pre-hardened layer. 5 is a cross-sectional view for explaining an example of the step of irradiating the pre-cured layer via the front panel with light to form a cured resin layer. Fig. 6 is a cross-sectional view showing an example of an image display device. Figure 7 (A) ~ (H) are diagrams for explaining the production sequence of test samples. Fig. 8 is a perspective view for explaining the method of measuring the shear strength of the pre-hardened layer. 9 is a graph showing the measurement results of the shear strength of the pre-hardened layer in the test samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2. 10 is a graph showing the measurement results of the shear strength of the pre-hardened layer in the test samples obtained in Example 7 and Comparative Examples 3 to 5. 11 is a graph showing the measurement results of the shear strength of the pre-hardened layer in the test samples obtained in Example 8 and Comparative Examples 6-8. 12 is a graph showing the measurement results of the shear strength of the pre-hardened layer in the test samples obtained in Example 9 and Comparative Examples 9-11. 13 is a graph showing the measurement results of the shear strength of the pre-hardened layer in the test samples obtained in Example 10 and Comparative Example 12. 14 is a graph showing the measurement results of the shear strength of the cured resin layer obtained by curing the pre-cured layer in the test sample obtained in Example 9.

1: Image display component

2: Curable resin layer

Claims (9)

A method for manufacturing an image display device, which has: Step A, which is to form a curable resin layer containing a photocurable resin composition on the surface of the front panel or the image display member; Step B, which irradiates light from the UV-LED to the curable resin layer to form a pre-cured layer; Step C: bonding the front panel and the image display member via the pre-hardened layer; and Step D, which is to irradiate the pre-hardened layer with light through the front panel to form a hardened resin layer; and The light irradiated in the above step B includes the first light having a peak in the range of wavelength 360-430 nm and the second light having a peak in the range of wavelength 200-345 nm, In the step B, the second light is irradiated to a portion of the curable resin layer where the curable resin layer is irradiated with the first light to cause oxygen inhibition. The method for manufacturing an image display device according to claim 1, wherein in the step B, the curable resin layer is irradiated with the first light so that the cumulative light amount of the first light is greater than the cumulative light amount of the second light And the second light mentioned above. The method for manufacturing an image display device according to claim 1 or 2, wherein in the step B, the surface of the curable resin layer is irradiated with the first light and the second light. The method for manufacturing an image display device according to any one of claims 1 to 3, wherein the thickness of the curable resin layer is 25-350 μm. The method for manufacturing an image display device according to any one of claims 1 to 4, wherein in step B, the cumulative light intensity of the first light is in the range of 2000-5000 mJ/cm ² , and the cumulative light of the second light The amount of light is more than 20 mJ/cm ² and less than 1000 mJ/cm ² . The method for manufacturing an image display device according to any one of claims 1 to 5, wherein the photocurable resin composition contains a photoradical reactive component, a photopolymerization initiator, a plasticizer, and an adhesion imparting component At least one. The method for manufacturing an image display device according to claim 6, wherein the photoradical reactive component contains at least one of (meth)acrylate oligomer and (meth)acrylate monomer. The method for manufacturing an image display device according to claim 6 or 7, wherein the photopolymerization initiator contains an alkyl ketone-based photopolymerization initiator, an oxyphosphine oxide-based photopolymerization initiator, and a benzophenone-based photopolymerization initiator. At least one of a polymerization initiator and an intramolecular hydrogen abstraction type photopolymerization initiator. The method for manufacturing an image display device according to any one of claims 6 to 8, wherein the photocurable resin composition contains 30 to 90% by mass of the photo radical reactive components in total, and the photopolymerization initiator 2 to 6 mass %, and at least one of the plasticizer and the adhesion imparting component 5 to 58 mass %.

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