CN110930864B

CN110930864B - Method for manufacturing image display device

Info

Publication number: CN110930864B
Application number: CN201910848015.6A
Authority: CN
Inventors: 高桥宏; 渡边明彦
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2018-09-19
Filing date: 2019-09-09
Publication date: 2023-05-05
Anticipated expiration: 2039-09-09
Also published as: JP6538252B1; JP2020046557A; CN110930864A; TWI831835B; KR20200033173A; TW202025110A

Abstract

The invention provides a method for manufacturing an image display device with good adhesion performance during temporary curing. The method for manufacturing an image display device according to the present technology includes the steps of: a step A of forming a curable resin layer 2 composed of a photocurable resin composition on the surface of the front panel 4 or the image display member 1; a step B of irradiating the curable resin layer 2 with light from a UV-LED to form a temporary cured layer 5; a step C of bonding the front panel 4 to the image display member 1 via the temporary cured layer 5; and a step (D) of irradiating the temporary cured layer (5) with light through the front panel (4) to form a cured resin layer (6). The light irradiated in the step B includes the 1 st light having a peak in a wavelength range of 360 to 430nm and the 2 nd light having a peak in a wavelength range of 200 to 345 nm. In step B, the 1 st light is irradiated to the curable resin layer 2, and the 2 nd light is irradiated to the portion of the curable resin layer 2 where the oxygen inhibition occurs.

Description

Method for manufacturing image display device

Technical Field

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

Background

Patent document 1 describes a method for manufacturing a display device, the method including: a first irradiation step (temporary curing step) of irradiating light to an adhesive applied to at least one of the display panel and the substrate; a bonding step of bonding the display panel and the substrate after the first irradiation step; and a second irradiation step (main curing step) of further irradiating the adhesive with light after the bonding step.

The cured state of the outermost surface of the resin in the temporary curing step is very important in maintaining alignment at the time of bonding. Regarding the cured state of the outermost surface of the resin, the larger the influence of oxygen inhibition (oxygen inhibition) upon temporary curing, the lower the curing rate, and accordingly the adhesive function tends to be lowered. Therefore, as the ultraviolet irradiation device, a device having a wide wavelength range and a high output, such as a metal halide lamp or a high-pressure mercury lamp, is preferable.

However, in recent years, due to the requirement of high life performance of ultraviolet irradiation devices, there is a tendency that, for example, UV-LEDs having peaks in the wavelength range of 360 to 430nm are used as light sources in many cases. Since such UV-LEDs are used at a single wavelength, there is a concern that the adhesion performance at the time of temporary curing is lowered due to the influence of oxygen inhibition.

Prior art literature

Patent literature

Patent document 1: international publication No. WO 2009/054168.

Disclosure of Invention

Problems to be solved by the invention

The present technology has been made in view of such conventional circumstances, and provides a method for manufacturing an image display device having excellent adhesion performance at the time of temporary curing.

Means for solving the problems

The method for manufacturing an image display device according to the present technology includes the steps of: step A of forming a curable resin layer composed of a photocurable resin composition on the surface of a front panel or an image display member; a step B of irradiating the curable resin layer with light from a UV-LED to form a temporary cured layer; step C, bonding the front panel and the image display component through the temporary curing layer; and a step (D) of irradiating the temporary cured layer with light through the front panel to form a cured resin layer, wherein the light irradiated in the step (B) includes a 1 st light having a peak in a wavelength range of 360-430 nm and a 2 nd light having a peak in a wavelength range of 200-345 nm, and the 1 st light is irradiated to the cured resin layer and the 2 nd light is irradiated to a portion of the cured resin layer where oxygen inhibition occurs.

Effects of the invention

According to the present technology, the adhesion performance at the time of temporary curing can be improved.

Drawings

FIG. 1 is a sectional view showing an example of a process for forming a curable resin layer composed 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 process of forming a temporary cured layer by irradiating a curable resin layer with light from a UV-LED.

Fig. 3 is a cross-sectional view for explaining an example of a process 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 for explaining an example of a process of bonding the front panel and the image display member via the temporary cured layer.

Fig. 5 is a cross-sectional view for explaining an example of a process of forming a cured resin layer by irradiating a temporary cured layer with light through a front panel.

FIG. 6 is a sectional view showing an example of an image display device.

FIG. 7A to H are diagrams for explaining the procedure of producing test samples.

FIG. 8 is an oblique view for explaining a method of measuring the shear strength of a temporary cured layer.

Fig. 9 is a graph showing the measurement results of the shear strength of the temporary cured layer 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 temporary 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 temporary 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 temporary 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 temporary cured layer in the test samples obtained in example 10 and comparative example 12.

Fig. 14 is a graph showing the measurement result of the shear strength of the cured resin layer obtained by subjecting the temporary cured layer in the test sample obtained in example 9 to main curing.

Detailed Description

Hereinafter, details of a method for manufacturing an image display device according to the present technology (hereinafter, also referred to as the present manufacturing method) will be described. In the following description, (meth) acrylate includes both acrylate and methacrylate. In addition, the (meth) acryl group includes both acryl and methacryl groups.

The manufacturing method comprises the following steps: step A of forming a curable resin layer composed of a photocurable resin composition on the surface of a front panel or an image display member; a step B of irradiating the curable resin layer with light from a UV-LED to form a temporary cured layer; step C, bonding the front panel and the image display component through the temporary curing layer; and a step D of irradiating the temporary cured layer with light through the front panel to form a cured resin layer. The light irradiated in the step B includes the 1 st light having a peak in a wavelength range of 360 to 430nm and the 2 nd light having a peak in a wavelength range of 200 to 345 nm. In step B, the 1 st light is irradiated to the curable resin layer, and the 2 nd light is irradiated to the portion of the curable resin layer where oxygen polymerization inhibition occurs. The energy of the 1 st light having a peak in the wavelength range of 360 to 430nm is smaller than that of the 2 nd light having a peak in the wavelength range of 200 to 345nm, and the light reaches the deep portion of the curable resin layer. On the other hand, the energy of the 2 nd light having a peak in the wavelength range of 200 to 345nm is larger than that of the 1 st light having a peak in the wavelength range of 360 to 430nm, and the 2 nd light does not reach the deep portion of the curable resin layer but only reaches the surface layer portion of the curable resin layer. By using the 1 st light having a peak in the range of 360 to 430nm and the 2 nd light having a peak in the range of 200 to 345nm in combination as the light irradiated in the step B, the influence of oxygen inhibition can be reduced and the adhesive property at the time of temporary curing can be improved as compared with the case of irradiating only the 1 st light having a peak in the range of 360 to 430 nm.

< procedure A >)

In step a of the present manufacturing method, as shown in fig. 1, a structure composed of a photocurable resin composition is formed on the surface of the image display member 1And a resultant curable resin layer 2. For example, in the 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 set to a thickness such that a step (step difference) formed by the light shielding layer 3 and the light shielding layer formation side surface of the front panel 4 described later is eliminated, and may be 2.5 to 40 times, 2.5 to 12.5 times, or 2.5 to 4 times the thickness of the light shielding layer 4. For example, the thickness of the curable resin layer 2 may be 25 to 350μm may be 50 to 150μm. The number of applications of the photocurable resin composition is not particularly limited as long as the number of applications is such that the required resin thickness is obtained, and may be 1 or more.

The image display member 1 is, for example, an image display panel in which a polarizing plate (polarizing plate) is formed on the recognition side surface of an image display unit. Examples of the image display unit include a liquid crystal unit and an organic EL unit. Examples of the liquid crystal cell include a reflective liquid crystal cell and a transmissive 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 is 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 (Touch pad) are combined.

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 a tackifying component, and a photopolymerization initiator. The photocurable resin composition may further contain other components within a range that does not impair the technical effects of the present invention.

< photoradical reactive component >

The photoradical reactive component comprises at least one of a (meth) acrylate oligomer and a (meth) acrylate monomer. The (meth) acrylate oligomer preferably has polyisoprene, polyurethane, polybutadiene, etc., in the skeleton, particularly a urethane (meth) acrylate oligomer. The (meth) acrylate oligomer preferably has 1 to 4 (meth) acrylate groups, more preferably 2 to 3 (meth) acrylate groups. Examples of the commercial urethane (meth) acrylate oligomer include CN9014 (manufactured by Sartomer corporation), EBECRYL 230, and EBECRYL 270 (manufactured by Daicel Allnex corporation).

The (meth) acrylate monomer is used as a reactive diluent for imparting sufficient reactivity, coatability, and the like to the photocurable resin composition. The (meth) acrylate monomer may be a monofunctional (meth) acrylate, a difunctional (meth) acrylate, or a multifunctional (meth) acrylate. For example, from the viewpoint of compatibility with other components, the (meth) acrylate monomer preferably contains: (meth) acrylate monomers having a hydroxyl group (e.g., 4-hydroxybutyl acrylate), (meth) acrylate monomers having a cyclic structure (e.g., isobornyl acrylate, dicyclopentenyloxyethyl methacrylate), alkyl (meth) acrylate monomers having 5 to 20 carbon atoms (e.g., n-octyl acrylate, isodecyl acrylate, lauryl acrylate, isostearyl acrylate), polyfunctional (meth) acrylate monomers (e.g., pentaerythritol (tri/tetra) acrylate, neopentyl glycol hydroxypivalate) and the like.

The total content of the (meth) acrylate oligomer and the (meth) acrylate monomer in the photocurable resin composition may be 95 mass% or less, and may be 90 mass% or less. The total content of the (meth) acrylate oligomer and the (meth) acrylate monomer in the photocurable resin composition may be 20 mass% or more, 30 mass% or more, or 35 mass% or more. The (meth) acrylate oligomer and/or the (meth) acrylate monomer may be used singly or in combination of two or more. In the case where two or more (meth) acrylate oligomers and/or (meth) acrylate monomers are used in combination, the total content thereof is preferably within the above-mentioned range.

< photopolymerization initiator >)

The photopolymerization initiator may be a known photo radical polymerization initiator. As the photopolymerization initiator, an alkylbenzene ketone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, a benzophenone photopolymerization initiator, an intramolecular hydrogen abstraction photopolymerization initiator, and the like can be used. Specific examples thereof include 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, 1-hydroxycyclohexyl phenyl ketone, methyl phenylglyoxylate and the like. Examples of the commercial products include LUCIRIN TPO, irgacure184, IRGACURE MBF (manufactured by BASF corporation as described above), esacure TZT (manufactured by Lamberti corporation), and the like.

The content of the photopolymerization initiator in the photocurable resin composition may be 10 mass% or less, 8 mass% or less, or 6 mass% or less in total. The content of the photopolymerization initiator in the photocurable resin composition may be 0.1 mass% or more, 1 mass% or more, or 2 mass% or more in total. The photopolymerization initiator may be used alone or in combination of two or more. In the case where two or more photopolymerization initiators are used in combination, the total content thereof is preferably within the above range.

Plasticizer and tackifier >

Plasticizers and tackifiers are substances that do not substantially react with the (meth) acrylate oligomer and the (meth) acrylate monomer by light irradiation. Examples of the thickening component include a solid thickening agent and a liquid oil component. As solid tackifiers, there may be mentioned: terpene resins such as terpene resins, terpene phenolic resins and hydrogenated terpene resins; rosin resins such as natural rosin, polymerized rosin, rosin ester, and hydrogenated rosin; terpene-based hydrogenated resins. The liquid oil component may be polybutadiene-based oil, polyisoprene-based oil, or the like. Examples of commercial products of plasticizers and tackifiers include clear M105 (manufactured by YASUHARA CHEMICAL), GI-1000, and GI-3000 (manufactured by japan soyata).

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 may be 70 mass% or less, 65 mass% or less, 60 mass% or less, or 58 mass% or less. The total content of the plasticizer and the tackifier in the photocurable resin composition may be 0.5 mass% or more, may be 2 mass% or more, may be 4 mass% or more, may be 5 mass% or more, and may be 7 mass% or more. The plasticizer and/or tackifier may be used singly or in combination of two or more. In the case where 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 Components >)

The photocurable resin composition may contain, for example, a polymer component (a polymer component other than the above-described photoradical reactive component, plasticizer and tackifier), an antioxidant, a light stabilizer, a silane coupling agent, and the like, in addition to the above-described components, to the extent that the technical effects are not impaired. As the polymer component, HITALOID 7927 (manufactured by Hitachi chemical Co., ltd.) can be used, for example. The 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, when the photocurable resin composition contains HITALOID 7927, the HITALOID 7927 content in the photocurable resin composition is calculated as the content of the tackifier. As the antioxidant, for example, a hindered phenol-based antioxidant can be used. As a commercial product of the antioxidant, IRGANOX 1520L, IRGANOX 1010 (manufactured by BASF corporation, above) can be used, for example. As the light stabilizer, for example, a hindered amine light stabilizer can be used. As a commercially available product of the light stabilizer, for example, ADK STAB LA-52 (manufactured by ADEKA Co., ltd.) can be used. As the silane coupling agent, for example, 3-acryloxypropyl trimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane can be used. Examples of the commercially available silane coupling agents include KBM5103, KBM503, and KBM803 (manufactured by Siphone Co., ltd.).

< procedure B >)

In step B of the present manufacturing method, light is irradiated from the UV-LED to the curable resin layer 2 as shown in fig. 2 to form a temporary cured layer 5 as shown in fig. 3. In step B, the curable resin layer 2 formed in step A is irradiated with the 1 st light having a peak in the wavelength range of 360 to 430nm and the 2 nd light having a peak in the wavelength range of 200 to 345 nm.

The light irradiation in the step B is preferably performed so that the reaction rate of the temporary cured layer 5 is 10 to 90%, more preferably 40 to 90%, and even more preferably 70 to 90%. The reaction rate is a numerical value defined as a ratio (consumption ratio) of the amount of (meth) acryloyl groups present after light irradiation to the amount of (meth) acryloyl groups present in the curable resin layer before light irradiation. The larger the value of this reaction rate, the more curing proceeds. Specifically, the reaction rate can be determined by measuring the FT-IR of the curable resin layer before irradiation with light in a range of 1640 to 1620cm from the base line ^-1 Is 1640 to 1620cm from the base line in the FT-IR measurement chart of the absorption peak height (X) and the curable resin layer (cured resin layer 6) after light irradiation ^-1 The absorption peak height (Y) of (C) is calculated by substituting the following formula.

Reaction rate (%) = [ (X-Y)/X ] ×100

In the step B, it is preferable that the curable resin layer 2 is irradiated with the 1 st light having a peak in the range of 360 to 430nm to cause oxygen inhibition, and specifically, the surface of the curable resin layer 2 is irradiated with the 1 st light having a peak in the range of 360 to 430nm and the 2 nd light having a peak in the range of 200 to 345 nm.

In step B, it is preferable to irradiate light such that the cumulative light amount of the 1 st light having a peak in the wavelength range of 360 to 430nm is larger than the cumulative light amount of the 2 nd light having a peak in the wavelength range of 200 to 345 nm. This can improve the adhesion performance at the time of temporary curing. As an example, it is preferable that the cumulative light amount of the 1 st light having a peak in the wavelength range of 360 to 430nm is 2000 to 5000mJ/cm ² The cumulative light amount of the 2 nd light having a peak in the wavelength range of 200 to 345nm is 20mJ/cm ² Above and below 1000mJ/cm ² Is not limited in terms of the range of (a). In the step B, the illuminance is preferably 100 to 500mW/cm ² For example, light having an emission wavelength of 365.+ -.5 nm is irradiated as the first light having a peak in the range of 360 to 430nm1 light. In the step B, the illuminance is preferably 10 to 100mW/cm ² For example, light having an emission wavelength of 280.+ -.5 nm is irradiated as the 2 nd light having a peak in the wavelength range of 200 to 345 nm. Examples of the UV-LED used in the step B include an LED having an emission peak wavelength in the range of 360 to 430nm (an example of which is 365.+ -.5 nm) and an LED having an emission peak wavelength in the range of 200 to 345nm (an example of which is 280.+ -.5 nm).

In the step B, the 1 st light having a peak in the wavelength range of 360 to 430nm may be irradiated simultaneously with the 2 nd light having a peak in the wavelength range of 200 to 345 nm. In step B, the 1 st light having a peak in the wavelength range of 360 to 430nm may be irradiated, followed by the 2 nd light having a peak in the wavelength range of 200 to 345 nm. In step B, the 2 nd light having a peak in a wavelength range of 200 to 345nm may be irradiated, followed by the 1 st light having a peak in a wavelength range of 360 to 430 nm.

In the present manufacturing method, it is preferable that the temporary cured layer 5 is kept in a state where no dripping or deformation occurs when the bonding operation in step C described later is performed. For example, in the step B, it is preferable to irradiate the curable resin layer 2 with light before the 1 st light having a peak in the wavelength range of 360 to 430nm and the 2 nd light having a peak in the wavelength range of 200 to 345nm so that the viscosity of the curable resin layer 2 becomes 20 Pa.S or more (cone-plate rheometer, 25 ℃, cone and plate C35/2, rotation speed of 10 rpm).

< procedure C >)

In step C, for example, as shown in fig. 4, the front panel 4 is bonded to the image display member 1 via the temporary cured layer 5. For example, in step C, the front panel 4 is bonded to the image display member 1 from the temporary cured layer 5 side. The bonding can be performed by pressurizing at 10 to 80 ℃ using a known pressing device, for example.

The front panel 4 may have a light transmittance such that an image formed on the image display member 2 can be recognized, and examples thereof include a plate-like material or a sheet-like material such as glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate, and polycarbonate. These materials may be subjected to a hard coat treatment, an antireflection treatment, or the like on one or both sides thereof. The physical properties such as the thickness and the elastic modulus of the front panel 4 can be appropriately determined according to the purpose of use. The front panel 4 may be a panel formed by stacking various sheets or films such as a touch panel module.

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

< procedure D >)

In step D, the temporary cured layer 5 shown in fig. 5 is irradiated with light, for example, through the front panel 4, to form a cured resin layer 6 shown in fig. 6. The reason why the temporary cured layer 5 is formally cured in step D is that: the temporary cured layer 5 is sufficiently cured, and the image display member 1 and the front panel 4 are bonded and laminated. As shown in fig. 6, by performing step D, an image display device 7 including the image display member 1, the cured resin layer 6, and the front panel 4 in this order can be obtained.

The main curing (light irradiation) in 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. The type, output, illuminance, accumulated light amount, and the like of the light source at the time of the main curing are not particularly limited, and a photoradical polymerization process condition of the (meth) acrylic acid ester by known ultraviolet irradiation may be employed. For example, the ultraviolet irradiation is preferably performed by using an ultraviolet irradiator (metal halide lamp, high-pressure mercury lamp, UV-LED, etc.) at an illuminance of 50 to 300mW/cm ² The accumulated light quantity is 1000-6000 mJ/cm ² Is carried out under the condition of (2). In particular, in step D, it is preferable to use a UV-LED to irradiate the 1 st light having a peak in the wavelength range of 360 to 430nm, because of the requirement of the high lifetime performance of the ultraviolet irradiation device as described above.

In step D, the light shielding layer 3 of the front panel 4 and the temporary curing layer 5 between the image display member 1 are irradiated with light as necessary, whereby the temporary curing layer 5 can be cured formally.

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 range of 90% or more. By satisfying such a range, the visibility of the image formed on the image display unit 1 can be 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 panel 4. The refractive index of the cured resin layer 6 is preferably 1.45 or more and 1.55 or less, for example. This can improve the brightness and contrast of the image light from the image display unit 1 and enhance the visibility. The thickness of the cured resin layer 6 may be, for example, 25 to 200μm is about.

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

In the step a, instead of coating the surface of the image display member 1 with the photocurable resin composition, the surface of the front panel 4 on the side where the light shielding layer 3 is formed may be coated with the photocurable resin composition. As the front panel, a front panel having no light shielding layer 3 may be used.

Examples

Hereinafter, embodiments of the present technology will be described. It should be noted that the present technology is not limited by these examples.

Preparation of photocurable resin composition

The components were uniformly mixed in the blending amounts (parts by mass) shown in table 1 to prepare photocurable resin compositions.

TABLE 1

The shorthand symbols in table 1 refer to the following compounds.

Urethane acrylate oligomer: the number average molecular weight is 20000;

CN9014: urethane acrylate oligomer manufactured by Sartomer company;

HITALOID 7927: manufactured by hitachi chemical company;

4HBA: 4-hydroxybutyl acrylate manufactured by BASF corporation;

ISTA: isostearyl acrylate, manufactured by osaka organic chemical company;

miramer M210: hydroxypivalic acid neopentyl glycol diacrylate, manufactured by MIWON corporation;

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, YASUHARA CHEMICAL company;

GI-1000: hydrogenated polybutadiene having two terminal hydroxyl groups, manufactured by Nippon Caddy;

GI-3000: hydrogenated polybutadiene having two terminal hydroxyl groups, manufactured by Nippon Caddy;

terpene resin: a number average molecular weight of 800;

TPO:2,4, 6-trimethylbenzoyl diphenyl phosphine oxide, product name: LUCIRIN TPO, BASF;

irg184D: 1-hydroxycyclohexyl phenyl ketone, product name; irgacure184, manufactured by BASF corporation;

MBF: methyl phenylglyoxylate, product name; IRGACURE MBF, manufactured by BASF corporation;

TZT: product name; esacure TZT, manufactured by Lamberti, inc.

Example 1

Preparation of test sample Using resin A

As shown in fig. 7 a, the thickness of the PET film 10 (thickness 130 mm) was 33 by applying the photocurable resin composition 12 from one end side to the other end side of the surface by the slit nozzle 11μm, and then, the UV-LED13 irradiates light having a peak at 365nm wavelength to the applied photocurable resin composition 12 to make the cumulative light quantity reach 500mJ/cm ² . The light irradiation is performed for the purpose of suppressing dripping of the applied photocurable resin composition. Thereby, the 1 st curable resin layer 14A is formed. Next, as shown in fig. 7 (B), the photocurable resin composition 12 was applied onto the curable resin layer 14A by the slit nozzle 11 to a thickness of 33 aμm, and then irradiating the applied photocurable resin composition 12 with light having a peak at a wavelength of 365nm from a UV-LED13 to a cumulative light amount of 500mJ/cm ² Thereby forming the curable resin layer 14B of layer 2. The light irradiation is also performed for the purpose of suppressing dripping of the applied photocurable resin composition. Next, as shown in fig. 7 (C), the photocurable resin composition 12 was applied onto the curable resin layer 14B by the slit nozzle 11 to a thickness of 33 aμm, and then irradiating the applied photocurable resin composition 12 with light having a peak at a wavelength of 365nm by a UV-LED13 to bring the cumulative light amount to 500mJ/cm ² Thereby forming the curable resin layer 14C of layer 3. The light irradiation is also performed for the purpose of suppressing dripping of the applied photocurable resin composition. Thus, a PET film 10 having a thickness of about 100A was obtainedμm, and a curable resin layer 14.

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

As shown in fig. 7 (E), the laminate was cut so that the width of the laminate reached 25 mm. As shown in fig. 7 (F), the cut laminate was attached to a slide glass 16 (width 25mm, thickness 1 mm). As shown in fig. 7 (G), a 2kg load roller 17 was used to press from the laminate side. Thus, a test sample 18 shown in fig. 7 (H), that is, a test sample 18 in which the PET film 10 and the slide glass 16 were bonded via the temporary cured layer 15 (10 mm×25mm, thickness 0.1 mm) was obtained.

< determination of shear Strength of temporarily cured layer >

The shear strength of the provisionally cured layer 15 in the test sample 18 was measured by the method shown in fig. 8. Specifically, the shear strength of the provisionally cured layer 15 was measured by fixing the PET film 10 located below the test sample 18 with a jig 19 using a bench-type precision universal tester (manufactured by shimadzu corporation, automatic plotter), and peeling the slide glass 16 located above at a speed of 5 mm/min in the vertical direction via the jig 20. The results are shown in FIG. 9 and Table 2.

Examples 2 to 6 and comparative examples 1 and 2

Test samples were prepared in the same manner as in example 1 except that the cumulative amounts of light irradiated to the curable resin layers 14 of the laminate were as shown in the following table, and the shear strength of the temporary cured layer in the test samples was measured. The results are shown in FIG. 9 and Table 2.

TABLE 2

Example 7 and comparative examples 3 to 5

Test samples were prepared in the same manner as in example 1 except that the resin B was used and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate was as shown in the following table, and the shear strength of the provisionally cured layer in the test samples was measured. The results are shown in FIG. 10 and Table 3.

TABLE 3

Example 8 and comparative examples 6 to 8

Test samples were prepared in the same manner as in example 1 except that the resin C was used and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate was as shown in the following table, and the shear strength of the provisionally cured layer in the test samples was measured. The results are shown in FIG. 11 and Table 4.

TABLE 4

Example 9 and comparative examples 9 to 11

A test sample was prepared in the same manner as in example 1 except that the resin D was used and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate was as shown in the following table, and the shear strength of the temporary cured layer in the test sample was measured. In comparative example 10, only 600mW/cm was irradiated with UV-LED ² Light having a peak at 365nm in intensity makes the cumulative light amount 6000mJ/cm ² . The results are shown in FIG. 12 and Table 5.

TABLE 5

Example 10, comparative example 12

Test samples were prepared in the same manner as in example 1 except that the resin E was used and the cumulative amount of light irradiated to the curable resin layer 14 of the laminate was as shown in the following table, and the shear strength of the provisionally cured layer in the test samples was measured. The results are shown in FIG. 13 and Table 6.

TABLE 6

From the results of examples 1 to 10 and comparative examples 1 to 12, it is clear that: by including the 1 st light having a peak in the range of 360 to 430nm and the 2 nd light having a peak in the range of 200 to 345nm in the light irradiated from the UV-LED to the curable resin layer to form the temporary cured layer, the shear strength of the temporary cured layer, that is, the adhesive property at the time of temporary curing is good. Further, as is clear from the results of example 9 and comparative example 11: in example 9, adhesion performance at the time of temporary curing equal to or more than that at the time of irradiation with a metal halide lamp was achieved. Further, as can be seen from the results of examples 1 to 10: the tendency of improving the adhesive property at the time of temporary curing is not dependent on the composition ratio of the photocurable resin composition.

From the results of examples 1 to 6, it is clear that: in the case of using the resin A, in the step of irradiating light to the curable resin layer by UV-LED to form the temporary cured layer, the cumulative light amount of the 1 st light having a peak in the range of 360 to 430nm is preferably 2000 to 5000mJ/cm ² The cumulative light amount of the 2 nd light having a peak in the wavelength range of 200 to 345nm is 20mJ/cm ² Above and below 1000mJ/cm ² More preferably, the cumulative light amount of the 2 nd light having a peak in the wavelength range of 200 to 345nm is 500mJ/cm ² Above and below 1000mJ/cm ² Is not limited in terms of the range of (a).

It can be seen that: in example 8 and comparative examples 6 to 8, since the resin C containing the photopolymerization initiator exhibiting relatively smooth reactivity and having a large proportion of the plasticizer was used, the shear strength at the time of temporary curing tended to be less likely to be exhibited than in the case of using other resins, but the shear strength was 2 times or more exhibited in example 8 than in comparative examples 6 to 8.

It can be seen that: in 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 contained only light having a peak in the range of 360 to 430nm or only light having a peak in the range of 200 to 345nm, and therefore the adhesive property at the time of temporary curing was not good.

It can be seen that: in comparative example 4, although the cumulative light amount of light having a peak in the wavelength range of 360 to 430nm from UV-LEDs was made to be up to 8000mJ/cm ² However, since light having a peak in the wavelength range of 200 to 345nm was not irradiated, the shear strength was very low compared with example 7. It is also known that: comparison of light having a peak in the wavelength range of 200 to 345nm when irradiated onlyIn example 5, the shear strength was very low compared to example 7. From the above results, it can be seen that: in view of curability in the deep portion of the curable resin layer, it is necessary to use light having a peak in the wavelength range of 360 to 430nm and light having a peak in the wavelength range of 200 to 345nm in combination in the step of forming the temporary cured layer.

It can be seen that: in comparative example 10, although the illuminance of light having a peak in the wavelength range of 360 to 430nm from UV-LED was made to be as high as 600mW/cm ² And the cumulative light quantity is up to 6000mJ/cm ² However, since light having a peak in the wavelength range of 200 to 345nm was not irradiated, the measurement result of the shear strength was inferior to that of example 9.

< determination of shear Strength of cured resin layer >

Examples 9 to 1

The temporary cured layer of the test sample in example 9 was irradiated with 200mW/cm using a metal halide lamp (manufactured by USIO Co.) with a conveyor belt ² Light of such an intensity that the cumulative light quantity reaches 5000mJ/cm ² . Thereby, the temporary cured layer is completely cured, and a cured resin layer is formed. The cure rate of the cured resin layer was 97%. The shear strength of the cured resin layer was measured in the same manner as in the above-mentioned temporary cured layer. The results are shown in FIG. 14. In fig. 14, N1 to N4 represent the measurement results of shear strength for 4 test samples, while preparing 4 test samples. The average (x) in fig. 14 shows the average value of the measurement results of the shear strengths of N1 to N4.

Examples 9 to 2

The provisionally cured layer of the test sample in example 9 was irradiated with 200mW/cm using UV-LEDs ² Light having a peak at 365nm in intensity and having a cumulative light quantity of 5000mJ/cm ² . Thereby, the temporary cured layer is completely cured, and a cured resin layer is formed. The cure rate of the cured resin layer was 97%. The shear strength of the cured resin layer was measured in the same manner as in the above-mentioned temporary cured layer. The results are shown in FIG. 14.

Comparative example 9-1

The shear strength of the cured resin layer was measured in the same manner as in example 9-1, except that the test sample in comparative example 9 was used. The results are shown in FIG. 14.

Comparative example 9-2

The shear strength of the cured resin layer was measured in the same manner as in example 9-2, except that the test sample in comparative example 9 was used. The results are shown in FIG. 14.

From the results of examples 9-1, 9-2 and comparative examples 9-1 and 9-2, it is apparent that: the strength of the cured resin layer was almost the same. This is thought to be due to: the difference in physical adhesion (effect of oxygen inhibition) is remarkably reflected in the temporary curing, and the difference in chemical adhesion is further added after the final curing.

Symbol description

1: an image display section; 2: a curable resin layer; 3: a light shielding layer; 4: a front panel; 5: temporarily solidifying the layer; 6: curing the resin layer; 7: an image display device; 10: a PET film; 11: a slit nozzle; 12: a photocurable resin composition; 13: a UV-LED;14: a curable resin layer; 15: temporarily solidifying the layer; 16: a glass slide; 17: a load roller; 18: a test sample; 19: a clamp; 20: and (3) clamping.

Claims

1. A method for manufacturing an image display device, comprising the steps of:

step A of forming a curable resin layer composed of a photocurable resin composition on the surface of a front panel or an 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 panel to the image display member via the temporary cured layer; and

a step D of irradiating the temporary cured layer with light through the front panel to form a cured resin layer,

wherein the light irradiated in the step B includes the 1 st light having a peak in a wavelength range of 360 to 430nm and the 2 nd light having a peak in a wavelength range of 200 to 345nm,

in the step B, the 2 nd light is irradiated to a portion of the curable resin layer where the 1 st light is irradiated to generate oxygen inhibition.

2. The method of manufacturing an image display device according to claim 1, wherein in the step B, the 1 st light and the 2 nd light are irradiated to the curable resin layer so that an accumulated light amount of the 1 st light is larger than an accumulated light amount of the 2 nd light.

3. The method of manufacturing an image display device according to claim 1, wherein in the step B, the 1 st light and the 2 nd light are irradiated to the surface of the curable resin layer.

4. The method for manufacturing an image display device according to claim 1, wherein the thickness of the curable resin layer is 25 to 350μm。

5. The method of manufacturing an image display device according to claim 1, wherein in the step B, the cumulative light amount of the 1 st light is 2000 to 5000mJ/cm ² The cumulative light quantity of the 2 nd light is 20mJ/cm ² Above and below 1000mJ/cm ² Is not limited in terms of the range of (a).

6. The method for manufacturing an image display device according to claim 1, wherein the photocurable resin composition contains a photoradical reactive component, a photopolymerization initiator, and at least one of a plasticizer and a tackifier component.

7. The method of manufacturing an image display device according to claim 6, wherein the photoradical reactive component contains at least one of a (meth) acrylate oligomer and a (meth) acrylate monomer.

8. The method for manufacturing an image display device according to claim 6, wherein the photopolymerization initiator comprises at least one of an alkylbenzene ketone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, a benzophenone photopolymerization initiator, and an intramolecular hydrogen abstraction type photopolymerization initiator.

9. 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 mass% of the photoradical reactive component, 2 to 6 mass% of the photopolymerization initiator, and 5 to 58 mass% of at least one of the plasticizer and the tackifier component.