TWI700529B - Manufacturing method of image display device - Google Patents

Abstract

Provided is a method for manufacturing an image display device. The method can form a photocurable resin layer with a uniform thickness between an image display panel and a transparent substrate to prevent deterioration of image quality caused by incident external light.

It has the following steps: applying a liquid photocurable transparent resin composition 4 to a release sheet 12 to form a photocurable transparent resin layer 5 having bumps 10 on the outer edge 5a; performing light irradiation, The first light irradiation step of suppressing the flow of the photocurable transparent resin layer 5; the step of adhering the photocurable transparent resin layer 5 to the transparent substrate 3; the second step of performing light irradiation to pre-curing the photocurable transparent resin layer 5 Light irradiation step; peeling off the release sheet 12 from the photocurable transparent resin layer 5, and attaching the photocurable transparent resin layer 5 to the image display panel 2; and light irradiation to make the photocurable transparent The third light irradiation step in which the resin layer 5 is actually hardened.

Description

Manufacturing method of image display device

The present invention relates to a method of manufacturing an image display device by adhering and laminating an image display panel such as a liquid crystal display panel and a light-transmitting substrate such as a transparent protective glass arranged on the surface of a light-curable transparent resin layer through a light-curable transparent resin layer.

This application is based on Japanese Patent Application No. "Japanese Patent Application 2015-124573" filed in Japan on June 22, 2015, and claims priority, and by referring to this application, this application is used.

Image display devices such as liquid crystal display panels used in information terminals such as smartphones are manufactured by the following method: a photocurable transparent resin composition is arranged on an image display panel such as a liquid crystal display panel or an organic EL panel with transparent protection After light-transmitting transparent substrates such as glass, the composition is irradiated with ultraviolet rays and cured to form a light-curable transparent resin layer, whereby the image display panel and the transparent substrate are bonded and laminated (Patent Document 1).

As a method of supplying the photocurable transparent resin composition between the image display panel and the transparent substrate, the following method is used: the surface of the transparent substrate is coated with the photocurable transparent resin composition, and then the transparent substrate is coated with light The surface of the curable transparent resin composition is attached to the image display panel. Here, when applying the photocurable transparent resin composition to the transparent substrate, the photocurable transparent resin composition must be applied to the entire surface of the transparent substrate so as to be flat. The reason is that if the photocurable transparent resin composition is not coated flat, Bubbles will be introduced when it is attached to the image display panel later, and the image will be distorted after attachment.

As a method of supplying the photocurable transparent resin composition between the image display panel and the transparent substrate, for example, there is a method of applying the photocurable transparent resin composition to the transparent substrate using a dispenser. In this method, as shown in Figure 5, a light-transmitting covering member 20 is prepared. On the surface 20a of the light-transmitting covering member 20 facing the image display device, a dispenser 21 is used to apply a liquid light-curing transparent resin composition 22 Into a prescribed shape. Alternatively, as shown in FIG. 6, screen printing can be used to print the light-curable transparent resin composition 22 on the light-transmitting property through a screen 26 such as a mesh plate or a template (Stencil) with a doctor blade 27 The surface 20a of the covering member 20 is coated in a predetermined shape.

Next, as shown in FIG. 7, the light-transmitting covering member 20 is attached to the image display panel 23 from the surface 20 a side coated with the light-curable transparent resin composition 22. Thereby, the light-curable transparent resin composition 22 is spread between the image display panel 23 and the light-transmitting covering member 20, and the entire surface is filled.

However, with the method of using the dispenser 21, it is difficult to control the filling shape of the light-curable transparent resin composition 22 after the light-transmitting cover member 20 is attached to the image display panel 23. It overflows between the display panel 23 and the translucent cover member 20, and there exists a possibility that productivity will fall, such as the necessity of cleaning. In addition, although there is also a method of pre-coating a resin as a barrier dam to prevent overflow, other problems such as increased man-hours or a boundary line with the barrier dam appear.

In addition, when a mesh plate is used, air is introduced when the squeegee slides, and voids, etc. remain in the light-curable transparent resin layer, making it practically unusable. In addition, when a template is used, the light-curable transparent resin composition 22 enters the light-transmitting covering member 20 It cannot be used with low-viscosity resin or non-shakeable resin between metal template.

For the method of using such a dispenser or screen printing, as a method of supplying the photocurable transparent resin composition between the image display panel and the transparent substrate, there is also the use of a coating head to coat the photocurable transparent resin composition on Transparent substrate method. In this method, as shown in FIG. 8, the photocurable transparent resin composition 22 is sprayed from the nozzle tip of the coating head 24 onto the surface 20a of the translucent covering member 20 facing the image display panel 23, thereby as shown in FIG. 9(A As shown in ), a quadrangular photocurable transparent resin layer 25 is formed on the entire surface of the translucent covering member 20 with a predetermined thickness.

Next, as shown in FIG. 9(B), the light-curable transparent resin layer 25 formed on the surface 20a of the light-transmitting covering member 20 is irradiated with ultraviolet rays to be precured, thereby precuring. This is to change the photocurable transparent resin composition 22 from a liquid state to a state that does not flow significantly, thereby preventing it from dripping even if it is turned upside down, thereby improving operability.

Next, as shown in FIG. 9(C), the light-transmitting covering member 20 is attached to the image display panel 23 from the side of the light-curing transparent resin layer 25, and the light-curing transparent resin layer 25 is cured by irradiating ultraviolet rays. .

Patent Document 1: International Publication No. 2010/027041

Here, when the liquid photocurable transparent resin composition 22 is applied to the surface of a substrate such as the translucent covering member 20, as shown in FIG. 10, the outer edge of the photocurable transparent resin layer 25 may Extend and wet to the side. When it is attached to the image display panel 23, the thickness of the outer edge of the photocurable transparent resin layer 25 is insufficient, and the image display panel 23 and the translucent cover member are generated in the display area of the image display panel The light-curable transparent resin composition 22 is not finished between 20 Fully filled to form a gap area. Therefore, external light may enter the display area from the outer edge of the photocurable transparent resin layer 25, which may degrade the image quality.

In addition, as shown in FIG. 11, a transparent substrate such as a translucent cover member 20 is usually provided on the periphery of the surface facing the image display panel 23. In order to enhance the brightness or contrast of the displayed image, decorative printing is used. Shielding layer 30. When the light-shielding layer 30 is provided, and a step is formed between the main face 31 and the light-shielding layer 30, the photocurable transparent resin layer 25 will be formed on the light-shielding layer 30 and bulge higher than the upper part of the main face 31 The convex part 32. If the convex portion 32 formed on the light-curable transparent resin layer 25 is high, when the light-transmitting covering member 20 and the image display panel 23 are bonded together, air will also be mixed in between the image display panel 23 and the image. Although the quality may deteriorate, it is difficult to control the convex portion 32 with high accuracy.

In addition, when the liquid photocurable transparent resin composition 22 is applied to a transparent substrate such as the translucent covering member 20, as shown in FIG. 12, if the transparent substrate is bent, the photocurable transparent resin composition 22 If it accumulates in the recessed part, the photocurable transparent resin layer 25 cannot be formed to a uniform thickness.

Therefore, the object of the present invention is to provide a method for manufacturing an image display device, which can form a photocurable resin layer with a uniform thickness between the image display panel and the transparent substrate to prevent images caused by the incidence of external light Quality deterioration.

In order to solve the above-mentioned problems, the manufacturing method of the image display device of the present invention has the following steps: a liquid photocurable transparent resin composition is applied to a mold release sheet to form a convex portion on the outer edge portion that is higher than the main face The step of applying the light-curing transparent resin layer to the block; the first light-irradiating step of performing light irradiation to suppress the flow of the light-curing transparent resin layer; making the surface of the light-curing transparent resin layer adhere to the density of the transparent substrate合 step; light irradiation, The second light irradiation step of pre-curing the photocurable transparent resin layer; peeling the release sheet from the photocurable transparent resin layer, and attaching the photocurable transparent resin layer to the image display panel Step; and performing light irradiation to form a third light irradiation step of curing the photocurable transparent resin layer.

According to the present invention, since the light-curable transparent resin layer uses the smooth surface in contact with the surface of the release sheet as the attachment surface to the image display panel, it can be easily attached without introducing air bubbles. , There will be no voids due to spreading and wetting of the photocurable transparent resin composition at the outer edge. Therefore, the image display device manufactured by this step can prevent the image quality from deteriorating due to external light entering the gap formed between the image display panel and the transparent substrate.

1‧‧‧Video display device

2‧‧‧Image display panel

3‧‧‧Transparent substrate

3a‧‧‧surface

4‧‧‧Light-curing transparent resin composition

5‧‧‧Light-curing transparent resin layer

5a‧‧‧Outer edge

5b‧‧‧Main face

5c‧‧‧Smooth surface

6,30‧‧‧Shading layer

9‧‧‧Releasable sheet

9a‧‧‧surface

9b‧‧‧Concave face

10‧‧‧Bump

13‧‧‧Distributor for resin

20‧‧‧Translucent cover member

20a‧‧‧surface

21‧‧‧Distributor

22‧‧‧Liquid light-curing transparent resin composition

23‧‧‧Image display panel

24‧‧‧Coating head

25‧‧‧Light-curing transparent resin layer

26‧‧‧Sieve plate

27‧‧‧Scraper

31‧‧‧Main face

32‧‧‧Protrusion

Fig. 1 is a cross-sectional view showing an image display device.

2 is a cross-sectional view showing the manufacturing process of the present invention, (A) shows the step of applying a photocurable transparent resin composition to a release sheet and irradiating it with ultraviolet light, (B) shows the step of making the photocurable transparent resin layer The step of adhering to the transparent substrate, (C) represents the step of irradiating the photocurable transparent resin layer with ultraviolet light and pre-curing it, (D) represents the step of peeling the release sheet from the photocurable transparent resin layer, (E) represents a step of laminating a light-curable transparent resin on an image display panel and irradiating it with ultraviolet light to formally harden it.

Fig. 3 is a perspective view showing a step of applying a photocurable transparent resin composition to a release sheet by a resin dispenser.

Figure 4 shows a group of light-curable transparent resins filled in the concave surface formed on the release sheet A cross-sectional view of the state of completion.

Fig. 5 is a perspective view showing a step of applying a liquid light-curable transparent resin composition into a predetermined shape on the surface of a light-transmitting covering member using a dispenser.

Fig. 6 is a side view showing a step of printing a photocurable transparent resin composition on the surface of a translucent covering member using screen printing.

Fig. 7 is a perspective view showing a step of attaching a light-transmitting covering member to an image display panel from the surface side coated with a light-curing transparent resin composition.

Fig. 8 is a perspective view showing a step of ejecting a photocurable transparent resin composition from a coating head onto the surface of a translucent covering member to form a photocurable transparent resin layer.

9(A) is a cross-sectional view showing a light-transmitting covering member formed with a photocurable transparent resin layer, and FIG. 9(B) is a cross-sectional view showing a step of irradiating the photocurable transparent resin layer with ultraviolet light, and FIG. 9 (C) is a cross-sectional view showing a state where the light-transmitting covering member is bonded to the image display panel from the side of the light-curable transparent resin layer.

Figure 10 is a cross-sectional view showing the following state: the outer edge of the photocurable transparent resin layer spreads and wets to the side, and in the display area of the image display panel, a gap is formed in the image display panel and the light-transmitting covering The area between the components.

Fig. 11 is a cross-sectional view showing a state where a convex part protruding from the upper part of the main surface is formed on the upper part of the light-shielding layer of the photocurable transparent resin layer.

Fig. 12 is a cross-sectional view showing a state in which a photocurable transparent resin composition is accumulated in a concave portion of a curved transparent substrate, and the thickness of the photocurable transparent resin layer is not uniform.

Hereinafter, while referring to the drawings, the image display using the present invention will be described in detail The manufacturing method of the device. In addition, the present invention is not limited to the following embodiments, and of course various changes can be made without departing from the main spirit of the present invention. In addition, the drawings are illustrative, and the ratio of each size may be different from the actual one. Please refer to the following description to judge the specific dimensions. Moreover, the drawings also naturally include parts with different dimensional relationships or ratios.

[Image display device]

The image display device 1 manufactured by applying the present invention is shown in FIG. 1, through a light-curable transparent resin layer 5 formed of a liquid light-curable transparent resin composition 4, an image display panel 2 and a transparent cover are laminated The transparent substrate 3 of the component.

Examples of the image display panel 2 include a liquid crystal display panel, an organic EL display panel, a plasma display panel, a touch panel, and the like. Here, the touch panel means 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 pad.

As the transparent substrate 3, as long as it has light transmittance such as the image formed on the image display member, glass, acrylic resin, polyethylene terephthalate, polyethylene naphthalate (polyethylene naphthalate) can be exemplified. naphthalate), polycarbonate and other plate or sheet materials. These materials can be subjected to single-sided or double-sided hard coat treatment, anti-reflection treatment, etc. Physical properties such as the thickness and elasticity of the transparent substrate 3 can be appropriately determined according to the purpose of use.

The transparent substrate 3 is formed with a light-shielding layer 6 formed along the periphery on the surface 3a laminated with the image display panel 2. The light-shielding layer 6 is provided in order to enhance the contrast of the image, etc., and is formed by coating a paint colored black or the like by a screen printing method, etc., and drying and hardening it. The thickness of the light-shielding layer 6 is usually 5-100 μm.

[Photocurable transparent resin composition]

As the photocurable transparent resin composition 4 applied on the surface 3a of the transparent substrate 3, a liquid photocurable transparent resin composition is used because it is precured and fully cured by ultraviolet rays as described later. As shown in FIG. 2(A), the liquid photocurable transparent resin composition 4 is applied to the smooth surface 9a of the release sheet 9 described later, thereby forming the photocurable transparent resin layer 5 on this surface 9a. The photocurable transparent resin layer 5 has an outer edge portion 5a and a main surface portion 5b, and a bump portion 10 that is raised more than the main surface portion 5b is formed on the outer edge portion 5a. Here, the term “liquid” refers to a cone-plate type viscometer showing a viscosity of 0.01~100Pa‧s (25℃).

Such a photocurable transparent resin composition 4 can preferably exemplify containing an acrylate-based oligomer component (component (1)), an acrylate-based monomer component (component (2)), and a photopolymerization initiator (component (component (2)). Three)) as the principal component.

The acrylic oligomer of component (1) can be used as the base material of the light-curable transparent resin composition 4. Preferred specific examples include (meth)acrylate oligomers modified by polyisoprene, polyurethane, polybutadiene, etc. (for example, polyisoprene-based (meth)acrylic acid) Ester oligomer, polyurethane-based (meth)acrylate oligomer, polybutadiene-based (meth)acrylate oligomer, etc.). In addition, in this specification, the term "(meth)acrylate" includes acrylate and methacrylate.

Preferred specific examples of polyisoprene-based (meth)acrylate oligomers include: maleic anhydride adduct of polyisoprene polymer and 2-hydroxyethyl methacrylate (UC102 (molecular weight converted to polystyrene), Kuraray Co., Ltd.; UC203 (molecular weight converted to polystyrene), Kuraray Co., Ltd.; UC-1 (molecular weight approximately 25,000), Kuraray Co., Ltd. )Wait.

In addition, preferred specific examples of polyurethane-based (meth)acrylate oligomers include: Aliphatic urethane acrylate oligomer (EBECRYL230 (molecular weight 5000), Daicel Zhanxin Co., Ltd.; UA-1, Light Chemical Industries Co., Ltd.), etc.

As the polybutadiene-based (meth)acrylate oligomer, known ones can be adopted.

The acrylate monomer component of the component (2) is used as a reactive diluent because it imparts sufficient reactivity and coatability to the photocurable transparent resin composition 4 in the manufacturing process of the image display device. Examples of such acrylate monomers include 2-hydroxypropyl methacrylate, benzyl acrylate, dicyclopentenyloxyethyl methacrylate, and the like.

The photopolymerization initiator of component (3) can use known photoradical polymerization initiators, such as 1-hydroxy-cyclohexyl phenyl ketone (Irgacure 184, BASF Japan Co., Ltd.), 2-hydroxy-1 -{4-[4-(2-Hydroxy-2-methyl-propanyl)benzyl]phenyl}-2-methyl-1-propan-1-one (Irgacure127, BASF Japan Co., Ltd.), Benzophenone, acetophenone, etc.

This kind of photopolymerization initiator, with respect to the total of 100 parts by mass of component (1) acrylate oligomer and component (2) acrylate monomer, if it is too small, the curing will be insufficient when irradiated with ultraviolet rays, if too much , The outgas caused by cracking will increase, and there is a tendency for poor foaming. Therefore, it is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass.

The photocurable transparent resin composition 4 may further contain the component (four) a plasticizer component. The plasticizer component of component (4) is used in order to impart cushioning properties to the hardened resin layer and reduce the curing shrinkage rate of the light-curable transparent resin composition 4. It will not interact with the acrylic acid of component (1) under ultraviolet radiation. The ester oligomer component reacts with the acrylate monomer component of component (2). This plasticizer component contains solid tackifier (1) and liquid oil component (2).

The solid tackifier (1) includes terpene resins such as terpene resins, terpene phenol resins, hydrogenated terpene resins, and rosin resins such as natural rosin, polymerized rosin, rosin ester, and hydrogenated rosin. , Terpene hydrogenated resin. In addition, non-reactive oligomers obtained by polymerizing the aforementioned acrylate monomers with low molecular weight in advance can also be used. Specifically, a copolymer of butyl acrylate, 2-hexyl acrylate and acrylic acid or Copolymer of cyclohexyl acrylate and methacrylic acid, etc.

As the liquid oil component (2), polybutadiene-based oil, polyisoprene-based oil, or the like may be contained.

In addition, the photocurable transparent resin composition 4 may contain a chain transfer agent in order to adjust the molecular weight. For example, 2-mercaptoethanol, lauryl mercaptan, glycidyl mercaptan, hydrothioacetic acid, 2-ethylhexyl thioacetate, 2,3-dihydrothio-1-propanol, α- Methyl styrene dimer, etc.

In addition, the photocurable transparent resin composition 4 may further contain general additives such as adhesion improving agents such as silane coupling agents and antioxidants, as needed.

The photocurable transparent resin composition 4 may contain a plasticizer component (component (four)) in a range that does not impair the effect of the present invention. Therefore, the total content of the acrylic oligomer component of the component (1) and the acrylic monomer component of the component (2) in the photocurable transparent resin composition 4 is preferably 25 to 85% by mass, but the component ( 4) The content of the plasticizer component is in the range of 0-65% by mass.

[Manufacturing Steps of Image Display Device 1]

Next, the manufacturing steps of the image display device 1 will be described. The manufacturing process of the image display device 1 has the following steps: apply a liquid photocurable transparent resin composition to a release sheet to form A step of applying a photocurable transparent resin layer with bumps raised on the outer edge portion than the main face; a first light irradiation step of performing light irradiation to suppress the flow of the photocurable transparent resin layer; making the photocurable transparent resin The step of adhering the surface of the layer to the transparent substrate; performing light irradiation to pre-curing the photocurable transparent resin layer; and peeling the release sheet from the photocurable transparent resin layer, An attaching step of attaching the photocurable transparent resin layer to an image display panel; and a third light irradiation step of performing light irradiation to formally harden the photocurable transparent resin layer.

[Coating Step]

The coating step is as shown in Figure 2(A), which is the following step: the liquid photocurable transparent resin composition 4 is coated on the release sheet 9 to form a convex portion on the outer edge 5a that is higher than the main surface 5b The light-curable transparent resin layer 5 of the block portion 10.

The release sheet 9 supports the light-curable transparent resin layer 5 because the liquid light-curable transparent resin composition 4 is coated on the surface and hardened, and is preferably formed of a flexible material such as silicone rubber. The releasable sheet 9 is peeled from the photocurable transparent resin layer 5 after the transparent substrate 3 is adhered to the photocurable transparent resin layer 5 and is precured.

Regarding the release sheet 9, the surface 9a of the photocurable transparent resin composition 4 in the form of a coating liquid is formed smooth. Therefore, the surface of the photocurable transparent resin layer 5 formed on the smooth surface 9a in contact with the surface 9a is also smoothed. Therefore, as described later, by bonding the smooth surface of the photocurable transparent resin layer 5 to the image display panel 2, the photocurable transparent resin layer 5 can be formed on the image display panel 2 and the transparent substrate 3 with a uniform thickness. between.

As shown in FIG. 3, for example, the release sheet 9 applies the photocurable transparent resin composition 4 to the surface 9a by the dispenser 13 for resin. The resin dispenser 13 has: storage light hard The storage part of the chemically transparent resin composition 4, and the discharge port for spraying the photocurable transparent resin composition 4 of the storage part from the surface 9a of the release sheet 9. The ejection port of the resin dispenser 13 has a predetermined width corresponding to the width of the photocurable transparent resin layer 5 transferred to the transparent substrate 3, and the photocurable transparent resin composition 4 is ejected over the entire width of the ejection port.

Then, the resin dispenser 13 moves from one end side to the other end side in the longitudinal direction of the smooth surface 9a of the release sheet 9 while composing the liquid light-curing transparent resin with a pump (not shown) The product 4 is extruded and sprayed onto the surface 9a of the release sheet 9, thereby coating with a predetermined thickness. Thereby, a light-curable transparent resin layer 5 having a substantially rectangular shape is formed on the smooth surface 9a of the releasable sheet 9.

[Bump part]

This light-curable transparent resin layer 5 has an outer edge 5a and a main surface 5b. The wettability of the light-curable transparent resin composition 4 to the surface 9a of the release sheet 9 is formed along the outer edge 5a. The protruding bump 10 of the main face 5b. The light-curable transparent resin layer 5 has bumps 10 formed along the outer edge 5a, which prevents the light-curable transparent resin composition 4 from spreading and wetting to the side, and prevents the light-curable transparent resin composition 4 from being wetted The space between the releasable sheet 9 and the transparent substrate 3 is not sufficiently filled in the thickness direction, and voids are generated. In addition, even when the bump 10 is pressed against the transparent substrate 3 and the photocurable transparent resin composition 4 spreads to the side to wet, the photocurable transparent resin composition constituting the bump 10 can also be used 4 Fill the space between the releasable sheet 9 and the transparent substrate 3 to form a uniform photocurable transparent resin layer 5 in the thickness direction.

In addition, the bump portion 10 may be formed by controlling the ejection amount or the moving speed of the photocurable transparent resin composition 4 with the resin dispenser 13. For example, by making the ejection amount of one end and the other end of the moving direction of the resin dispenser 13 higher than the intermediate ejection amount, or moving The moving speeds of one end and the other end of the direction are lower than the middle moving speed, and the bumps 10 may be formed at both ends of the moving direction of the resin dispenser 13. In addition, by making the discharge amount at both ends of the discharge port of the resin distributor 13 higher than the middle discharge amount, the bump 10 can be formed along the moving direction of the resin distributor 13. In addition, when examining these ejection amounts and moving speeds, the distance between the surface 9a of the releasable sheet 9 and the ejection port can be studied separately. Alternatively, a convex portion may be formed on the surface 9a of the release sheet 9 along the outer edge of the coating area of the photocurable transparent resin composition 4, thereby forming the bump portion 10 corresponding to the convex portion.

In addition, the coating method of the photocurable transparent resin composition 4 is not limited to the method using the resin dispenser 13, and screen printing and other well-known coating methods can be used suitably. In the case of screen printing, the adhesion between the mold release sheet 9 made of a flexible material such as silicone rubber and the template will be improved, so it can also solve the problem of resin entering the gap between the two. problem.

[Concave face]

In addition, as shown in FIG. 4, the releasable sheet 9 may be provided on the surface 9a with a concave portion 9b that holds the photocurable transparent resin composition 4 in a predetermined shape. By coating the photocurable transparent resin composition 4 on the concave portion 9b, the spreading and wetting of the photocurable transparent resin composition 4 to the side can be suppressed, and a uniform light can be formed between the transparent substrate 3 and the thickness direction. Curable transparent resin layer 5. In addition, the shape of the concave portion 9b can be set arbitrarily.

[First light irradiation step]

After the step of applying the photocurable transparent resin composition 4 to the release sheet 9, as shown in FIG. 2(A), the following first light irradiation step is performed: the photocurable transparent resin layer 5 is irradiated with ultraviolet rays to promote Harden reaction and inhibit flow. In the first light irradiation step, it suppresses the liquid photocuring It is revealed that the resin composition 4 is spread and wetted and hardened to the extent that the shape of the photocurable transparent resin layer 5 can be maintained. Therefore, the first light irradiation step is preferably performed immediately after the photocurable transparent resin composition 4 is applied.

For the irradiation of ultraviolet rays, publicly known ultraviolet light sources such as LEDs, mercury lamps, metal halide lamps, and xenon lamps can be used. In addition, although the irradiation conditions may vary depending on the type of the photocurable transparent resin composition 4 or the light source, for example, LED: 365 nm, 500 mW/cm ² , and 1000 mJ/cm ^{2 can be used} .

The curing rate of the photocurable transparent resin layer 5 at this time is preferably 60% or more and 97% or less, and more preferably 70% or more and 95% or less. If the curing rate exceeds 97%, the curing reaction may proceed excessively, and the adhesion with the transparent substrate 3 may decrease or air may be introduced. In addition, if the curing rate is less than 60%, the shape may not be maintained, and the transparent substrate 3 may not adhere.

In addition, ultraviolet rays are preferably irradiated from the side of the photocurable transparent resin layer 5. However, when the releasable sheet 9 is formed of a material having light transmittance, it may be irradiated from the back side of the releasable sheet 9 . In addition, the surface side of the photocurable transparent resin layer 5 exposed to the air prevents hardening and the hardening reaction progresses slowly, while the hardening reaction on the side in contact with the surface 9a of the releasable sheet 9 easily proceeds.

[Close Step]

Next, as shown in FIG. 2(B), a bonding step of bonding the surface of the photocurable transparent resin layer 5 to the transparent substrate 3 is performed. With this step, the bumps 10 formed on the surface of the photocurable transparent resin layer 5 will be crushed by being pressed against the transparent substrate 3, thereby preventing damage to the outer edge 5a of the photocurable transparent resin layer 5 The light-curable transparent resin composition 4 spreads and wets to generate voids.

In addition, the mold release sheet can be formed by using flexible materials such as silicone rubber 9, the roller 11 is slid on the back surface of the release sheet 9, etc., and pressed, and the photocurable transparent resin layer 5 is transferred to the transparent substrate 3. Thereby, the bump portion 10 of the photocurable transparent resin layer 5 can be collapsed, and the air intervening in the contact surface with the transparent substrate 3 can be extruded and brought into close contact at the same time.

When adhering to the transparent substrate 3, even if a step difference occurs due to the flexible substrate or the like being bonded to the transparent substrate 3, the releasable sheet 9 having flexibility will absorb the step difference and can make the photocurable transparent The resin layer 5 is in close contact with the transparent substrate 3. Therefore, the transparent substrate 3 can increase the degree of freedom of arrangement of components such as flexible substrates.

In addition, since the photocurable transparent resin layer 5 is brought into close contact with the release sheet 9 by rotating the roller 11 or the like, regardless of the height of the bump 10, the bump 10 is crushed and formed uniformly Therefore, there is no need to control the height of the bump 10 with high accuracy.

In addition, since the releasable sheet 9 having flexibility is rolled by the roller 11 or the like, even if the transparent substrate 3 is bent, the light-curable transparent resin layer 5 can be closely adhered with the fluctuation of the surface of the transparent substrate 3. The photocurable transparent resin layer 5 can be formed on the surface of the transparent substrate 3 with a uniform thickness.

[Second light irradiation step]

Next, as shown in FIG. 2(C), the following second light irradiation step is performed: ultraviolet light is irradiated to the photocurable transparent resin layer 5 to pre-curing. In the second light irradiation step, by accelerating the curing reaction of the photocurable transparent resin layer 5, it is precured to the extent that it maintains its shape and can be peeled from the release sheet 9 (for example, 80 to 90% curing rate). Thereby, the surface of the photocurable transparent resin layer 5 in contact with the transparent substrate 3 also undergoes a curing reaction, and it is firmly adhered to the transparent substrate 3.

[Attaching steps]

Next, as shown in FIG. 2(D)(E), the following attaching step is performed: the photocurable transparent resin layer 5 is peeled from the release sheet 9 and the photocurable transparent resin layer 5 is attached to the image Display panel 2. Since the photocurable transparent resin layer 5 has been precured by the second light irradiation step, it remains in a state of being attached to the transparent substrate 3, and only the release sheet 9 is peeled off. Thereby, a smooth surface 5c contacting the surface 9a of the releasable sheet 9 appears on the photocurable transparent resin layer 5.

The smooth surface 5c of the photocurable transparent resin layer 5 is attached to the image display panel 2. The attachment of the image display panel 2 can be performed by using a well-known crimping device, for example, applying pressure at 10°C to 80°C. At this time, since the smooth surface 5c of the photocurable transparent resin layer 5 in contact with the surface 9a of the releasable sheet 9 is used as the attachment surface to the image display panel 2, it can be easily attached without air bubbles. To attach. In addition, since the photocurable transparent resin layer 5 is pre-cured, no voids are generated due to spreading and wetting of the photocurable transparent resin composition 4 at the outer edge portion 5a. Therefore, the image display device 1 manufactured in this step can prevent the image quality from deteriorating due to external light entering the gap formed between the image display panel 2 and the transparent substrate 3.

In addition, in the case of using a liquid crystal display panel as the image display panel 2, in general, a polarizing plate is arranged on the liquid crystal display portion to which the transparent substrate 3 is attached, and therefore, the photocurable transparent resin layer 5 supported by the transparent substrate 3 Will be laminated on the polarizing plate set on the image display panel 2. In the image display device 1 manufactured in this step, since the smooth surface 5c is attached to the polarizing plate, even when the photocurable transparent resin layer 5 is thermally shrunk due to the heat of the polarizing plate, voids can be suppressed This occurs to prevent the degradation of image quality caused by the incident external light.

[3rd light irradiation step]

Next, the following third light irradiation step is performed: light irradiation is performed on the light-curable transparent resin layer 5 sandwiched between the image display panel 2 and the transparent substrate 3 to formally harden it. By this, The image display panel 2 and the transparent substrate 3 are laminated via the photocurable transparent resin layer 5 to obtain the image display device 1. The curing rate of the photocurable transparent resin layer 5 in the third light irradiation step is preferably 90% or more, more preferably 95% or more.

In addition, the degree of light transmittance of the photocurable transparent resin layer 5 may be such that the image formed on the image display panel 2 can be visually recognized.

Claims (10)

A method of manufacturing an image display device has the following steps: coating step: applying a liquid light-curing transparent resin composition to a release sheet to form a light-curing bump with a convex portion on the outer edge portion than the main face Transparent resin layer; first light irradiation step: light irradiation to suppress the flow of the light-curable transparent resin layer; adhesion step: adhesion of the surface of the light-curable transparent resin layer to the transparent substrate; second light irradiation step : Perform light irradiation to pre-harden the light-curable transparent resin layer; attaching step: peel off the release sheet from the light-curable transparent resin layer, and attach the light-curable transparent resin layer to the image display panel ; And the third light irradiation step: light irradiation is performed to formally harden the photocurable transparent resin layer. For example, the method for manufacturing an image display device according to the first item of the patent application, wherein, in the first light irradiation step, light irradiation is performed from the side of the photocurable transparent resin layer. For example, the method for manufacturing an image display device according to the first patent application, wherein, in the first light irradiation step, the curing rate of the photocurable transparent resin layer is 60% or more and 97% or less. For example, the method for manufacturing an image display device according to any one of items 1 to 3 in the scope of patent application, wherein, in the third light irradiation step, a polarizing plate is arranged on the surface of the image display panel, and the polarizing plate and the light hardening are laminated Transparent resin layer. For example, the method for manufacturing an image display device according to any one of items 1 to 3 in the scope of the patent application, wherein the release sheet is provided with a concave portion that maintains the photocurable transparent resin composition in a predetermined shape. For example, the method for manufacturing an image display device according to any one of items 1 to 3 in the scope of the patent application, wherein the release sheet has flexibility. For example, the method for manufacturing an image display device according to the scope of the patent application, wherein, in the adhesion step, the release sheet is transferred to the transparent substrate to transfer the photocurable transparent resin layer to the Transparent substrate. For example, the method of manufacturing an image display device according to any one of items 1 to 3 in the scope of patent application, wherein the transparent substrate is a glass substrate. For example, the method for manufacturing an image display device according to any one of items 1 to 3 in the scope of patent application, wherein the photocurable transparent resin composition is coated on the release sheet by a coating head. For example, the method for manufacturing an image display device according to any one of items 1 to 3 in the scope of patent application, wherein the photocurable transparent resin composition is coated on the release sheet by screen printing.

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