HK1198438B - Method for producing optical member and use of uv-curable resin composition therefor - Google Patents

Description

Method for producing optical member and use of ultraviolet-curable resin composition for the same

Technical Field

The present invention relates to a method for manufacturing an optical member by bonding an optical substrate having a light shielding portion to another optical substrate, and an application of an ultraviolet curable resin composition used in the manufacturing method.

Background

In recent years, display devices capable of performing screen input by attaching a touch panel to a display screen of a display device such as a liquid crystal display, a plasma display, or an organic EL display have been widely used. The touch panel has the following structure: the glass plate or the resin film on which the transparent electrodes are formed is bonded to face each other with a slight gap therebetween, and a glass or resin transparent protective plate is bonded to the touch surface thereof as necessary.

There is a technique of using a double-sided adhesive sheet for bonding a glass plate or film having a transparent electrode formed thereon in a touch panel to a transparent protective plate made of glass or resin or bonding a touch panel to a display unit. However, the use of a double-sided pressure-sensitive adhesive sheet has a problem that bubbles are likely to be generated. As a technique to replace the double-sided adhesive sheet, a technique of bonding them using a flexible ultraviolet curable resin composition has been proposed.

On the other hand, in the transparent protective plate, a band-shaped light shielding portion is provided at the outermost edge in order to improve the contrast of a display image. When a transparent protective plate provided with a light-shielding portion is bonded using an ultraviolet curable resin composition, sufficient ultraviolet rays cannot reach a light-shielding region in the ultraviolet curable resin, which is a shadow of the light-shielding portion, due to the light-shielding portion, and the curing of the resin in the light-shielding region is insufficient. When the curing of the resin is insufficient, problems such as display unevenness of a display image in the vicinity of the light shielding portion occur.

As a technique for improving the curing of a resin in a light-shielding region, patent document 1 discloses a technique for curing a resin in a light-shielding region by containing an organic peroxide in an ultraviolet-curable resin and heating the resin after irradiation with ultraviolet rays. However, there is a fear that the heating step may damage the liquid crystal display device and the like. Further, in order to sufficiently cure the resin, a heating step of 60 minutes or more is generally required, and thus there is a problem of poor productivity. Patent document 2 discloses a technique of curing a resin in a light shielding region by irradiating ultraviolet rays from the outer side surface side of the light shielding portion formation surface. However, this method has a limitation because it is difficult to irradiate ultraviolet rays from the side surface due to the shape of the liquid crystal display device. Patent document 3 discloses a technique utilizing the slow-release property of a cationically polymerizable ultraviolet curable resin, but the resin after curing has poor flexibility.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4711354

Patent document 2: japanese laid-open patent publication No. 2009-186954

Patent document 3: japanese patent laid-open publication No. 2010-248387

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a method for producing an optical member using an ultraviolet-curable resin composition, which is capable of producing an optical member such as a touch panel or a display unit that is less damaged to an optical substrate and has good productivity, and which is capable of producing an optical member having a high degree of curing of the resin composition and high reliability.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by producing an optical substrate having a light shielding portion and another optical substrate bonded thereto by a method comprising specific steps 1 to 3 using an ultraviolet curable resin composition, and have completed the present invention. That is, the present invention relates to the following items (1) to (21).

(1) A method for producing an optical member comprising at least a pair of optical substrates, which is obtained by bonding a transparent optical substrate having a light-shielding portion on the surface thereof and another optical substrate bonded thereto by the steps comprising the following steps 1 to 3, by using an ultraviolet-curable resin composition,

step 1: a step of applying an ultraviolet-curable resin composition to a bonding surface of at least one of a transparent optical substrate having a light-shielding portion on the surface and another optical substrate bonded thereto to form a coating layer, selectively irradiating the following light-shielding region of the obtained coating layer with ultraviolet rays to selectively cure the light-shielding region, and forming a coating layer in an uncured state in the other portion,

the light-shielding region is a portion of the coating layer where ultraviolet rays are shielded by the light-shielding portion and ultraviolet rays are not irradiated when the coating layer is irradiated with ultraviolet rays by the transparent optical substrate having the light-shielding portion on the transmission surface thereof, which is obtained by bonding the two optical substrates,

step 2: a step of bonding the two optical substrates by sandwiching the coating layer obtained in the step 1 between bonding surfaces of the two optical substrates,

and step 3: and (2) irradiating a laminate having at least one pair of optical substrates bonded in the steps 1 and 2 with ultraviolet rays through the transparent optical substrate having a light-shielding portion to cure an uncured coating layer interposed between the two optical substrates.

(2) The method for manufacturing an optical member according to the above (1), further comprising, after the above step 3, a step 4 of,

and 4, step 4: and applying pressure to the bonded optical substrate.

(3) The method for producing an optical member according to the above (1) or (2), wherein in the step 1, when the light-shielded region is cured, a portion of the coating layer remaining uncured except the light-shielded region is masked with an ultraviolet shielding plate, and ultraviolet rays are irradiated.

(4) The method for producing an optical member according to any one of the above (1) to (3), wherein in the step 1, the ultraviolet irradiation amount is at least 200mJ/cm²。

(5) The method for producing an optical member according to any one of the above (1) to (4), wherein in step 1, the ultraviolet curable resin composition is applied to at least one of a surface of the optical substrate having the light shielding portion on the surface, on which the light shielding portion is provided, or a display surface of the display unit as the optical substrate to be bonded thereto, and the surface of the optical substrate having the light shielding portion on the surface, on the side having the light shielding portion, and the display surface of the display unit are bonded so as to face each other with the coating layer interposed therebetween.

(6) The method for producing an optical member according to any one of the above (1) to (5), wherein the optical substrate having a light-shielding portion on a surface thereof is at least one optical substrate selected from the group consisting of a transparent glass substrate having a light-shielding portion, a transparent resin substrate having a light-shielding portion, and a glass substrate having a light-shielding portion and a transparent electrode formed thereon, and the optical substrate bonded thereto is at least one optical substrate selected from the group consisting of a liquid crystal display unit, a plasma display unit, and an organic EL display unit.

(7) The method for producing an optical member according to any one of the above (1) to (6), wherein the ultraviolet curable resin composition is an ultraviolet curable resin composition containing a (meth) acrylate (A) and a photopolymerization initiator (B).

(8) The method for producing an optical member according to item (7), wherein the (meth) acrylate (A) is at least one selected from the group consisting of urethane (meth) acrylates, (meth) acrylates having a polyisoprene skeleton, and (meth) acrylate monomers.

(9) The method for producing an optical member according to the above (7) or (8), wherein both of (i) a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (ii) a (meth) acrylate monomer are contained as the (meth) acrylate (A).

(10) The method for producing an optical member according to the above (8) or (9), wherein the (meth) acrylate (A) is a urethane (meth) acrylate or a (meth) acrylate monomer having a polypropyleneoxy structure.

(11) The method for producing an optical member according to any one of the above (8) to (10), wherein the urethane (meth) acrylate is a urethane (meth) acrylate obtained by reacting polypropylene glycol, a polyisocyanate, and a hydroxyl group-containing (meth) acrylate.

(12) The method for producing an optical member according to the item (8) or (9), wherein the urethane (meth) acrylate has a weight average molecular weight of 7000 to 25000, and the (meth) acrylate having a polyisoprene skeleton has a number average molecular weight of 15000 to 50000.

(13) The method for producing an optical member according to any one of the above (8) to (12), wherein the other components than the (meth) acrylate (A) and the photopolymerization initiator (B) are contained, the urethane (meth) acrylate and the (meth) acrylate monomer are contained as the (meth) acrylate (A) in an amount of 20 to 80 wt% and 5 to 70 wt% based on the total amount of the ultraviolet curable resin composition, the photopolymerization initiator (B) is contained in an amount of 0.2 to 5 wt% based on the total amount of the ultraviolet curable resin composition, and the remainder is the other components.

(14) An optical member obtained by the method for producing an optical member according to any one of (1) to (13) above.

(15) A touch panel obtained by the method for producing an optical member according to any one of (1) to (13) above.

(16) A display device obtained by the method for manufacturing an optical member according to (5) above, comprising an optical base material having a light-shielding portion on a surface thereof on a display screen of a display unit.

(17) Use of an ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B) in the method for producing an optical member according to any one of the above (1) to (6).

(18) The use of the ultraviolet curable resin composition according to item (17), wherein the (meth) acrylate (A) is at least one selected from the group consisting of urethane (meth) acrylates, (meth) acrylates having a polyisoprene skeleton, and (meth) acrylate monomers.

(19) The use of the ultraviolet curable resin composition according to item (17) above, which comprises both (i) a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (ii) a (meth) acrylate monomer as the (meth) acrylate (A).

(20) The use of the ultraviolet-curable resin composition according to (18) or (19), wherein the urethane (meth) acrylate is a urethane (meth) acrylate obtained by reacting polypropylene glycol, a polyisocyanate and a hydroxyl group-containing (meth) acrylate.

(21) An ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B) for use in the method for producing an optical member according to any one of (1) to (13) above.

(22) The ultraviolet-curable resin composition according to the above (21), wherein the (meth) acrylate (A) is at least one selected from the group consisting of urethane (meth) acrylates, (meth) acrylates having a polyisoprene skeleton, and (meth) acrylate monomers.

(23) The method for producing an optical member according to item (7), wherein the ultraviolet curable resin composition further contains a softening component.

(24) The ultraviolet-curable resin composition according to the above (21), further comprising a softening component.

Effects of the invention

According to the present invention, a bonded optical member having less damage to an optical substrate, good productivity, and good curability and adhesion can be obtained, and for example, a touch panel including an optical substrate having a light shielding portion, a display unit including an optical substrate having a light shielding portion, or the like can be obtained. Further, it is possible to provide an optical member having high reliability in which the degree of curing of the resin in the light shielding portion is high, and display unevenness or the like does not occur in a display image in the vicinity of the light shielding portion.

Drawings

Fig. 1 is a step diagram showing an embodiment (first embodiment) of the manufacturing method of the present invention.

Fig. 2 is a step diagram showing another embodiment (second embodiment) of the production method of the present invention.

FIG. 3 is a step diagram showing the production steps of comparative example 1.

Fig. 4 is a schematic view of an optical member obtained by the present invention.

Detailed Description

First, a process for producing an optical member using the ultraviolet curable resin composition of the present invention will be described.

The method for producing an optical member of the present invention is characterized by bonding a transparent optical substrate having a light-shielding portion on the surface thereof to another optical substrate bonded thereto by the steps comprising the following steps 1 to 3 using an ultraviolet-curable resin composition,

step 1: a step of applying an ultraviolet-curable resin composition to a bonding surface of at least one of a transparent optical substrate having a light-shielding portion on the surface and another optical substrate bonded thereto to form a coating layer, selectively irradiating the following light-shielding region of the obtained coating layer with ultraviolet rays to selectively cure the light-shielding region, and forming a coating layer in an uncured state in the other portion,

step 2: a step of bonding the two optical substrates by sandwiching the coating layer obtained in the step 1 between bonding surfaces of the two optical substrates,

and step 3: and a step of irradiating a laminate having at least one bonded pair of optical substrates with ultraviolet rays through the transparent optical substrate having the light-shielding portion to cure the uncured coating layer interposed between the two optical substrates.

In the present specification, the "light-shielding region" or "light-shielding region at the time of bonding" refers to a portion of the coating layer to which ultraviolet rays are not irradiated, the ultraviolet rays being shielded by the light-shielding portion, when the coating layer is irradiated with ultraviolet rays through the transparent optical substrate having the light-shielding portion on the surface thereof, with the two optical substrates bonded to each other.

Hereinafter, a specific embodiment of the method for manufacturing an optical member according to the present invention through steps 1 to 3 will be described with reference to the drawings, taking as an example a case where a liquid crystal display cell is bonded to a transparent substrate having a light shielding portion.

(first embodiment)

FIG. 1 is a process diagram showing a first embodiment of a method for producing an optical member using an ultraviolet curable resin composition of the present invention.

The first embodiment is a method of obtaining an optical member (a liquid crystal display unit having a light shielding portion) by bonding a liquid crystal display unit 1 and a transparent substrate 2 having a light shielding portion.

The liquid crystal display unit 1 is a unit in which a polarizing plate, a driving circuit, a signal input cable, and a backlight unit are provided in a unit in which a liquid crystal material is sealed between a pair of substrates on which electrodes are formed.

The transparent substrate 2 having a light-shielding portion is a substrate in which a black frame-shaped light-shielding portion 4 is provided on a surface of a bonding surface of a transparent substrate 3 such as a glass plate, a polymethyl methacrylate (PMMA) plate, a Polycarbonate (PC) plate, or an alicyclic polyolefin polymer (COP) plate.

Here, the light shielding portion 4 is provided by attaching a tape, applying paint, printing, or the like.

(step 1)

First, as shown in fig. 1(a), an ultraviolet curable resin composition is applied to each of the display surface of the liquid crystal display unit 1 and the surface of the transparent substrate 2 having a light shielding portion, on which the light shielding portion is provided. Examples of the coating method include a slit coater, a roll coater, a spin coater, and a screen printing method. Here, the ultraviolet curable resin compositions applied to the surfaces of the liquid crystal display unit 1 and the transparent substrate 2 having the light shielding portion may be the same, or different ultraviolet curable resin compositions may be used. Generally, it is preferable that both are the same ultraviolet-curable resin composition.

The thickness of the cured product of each ultraviolet-curable resin composition is adjusted so that the resin cured layer 7 after bonding is 50 to 500 μm, preferably 50 to 350 μm, and more preferably 100 to 350 μm.

The coated layer 5 of the ultraviolet curable resin composition after coating is selectively irradiated with ultraviolet light in the light-shielding region during bonding (the coating layer portion located in the light-shielding region where ultraviolet light is shielded by the light-shielding portion when the laminate obtained by bonding the liquid crystal display unit 1 and the transparent substrate 2 having the light-shielding portion is irradiated with ultraviolet light from the transparent substrate 2 side having the light-shielding portion) to obtain the coated layer 7 of the ultraviolet curable resin composition after selectively curing the light-shielding region during bonding. At this time, when ultraviolet light is irradiated, the exposure region at the time of bonding (the coating layer portion exposed to ultraviolet light when ultraviolet light is irradiated from the transparent substrate 2 side having a light shielding portion to the laminate obtained by bonding two optical substrates) is covered with an ultraviolet shielding plate so that the exposure region at the time of bonding is not cured.

The dose of ultraviolet radiation at this time is preferably 200mJ/cm²Above, 1000mJ/cm is particularly preferable²The above. When the irradiation amount is too small, the degree of curing of the light shielding portion of the optical member after final bonding may be insufficient. The upper limit of the dose of ultraviolet light is not particularly limited, but is preferably 4000mJ/cm²Hereinafter, more preferably 3000mJ/cm²The following.

The light source used for ultraviolet irradiation to near ultraviolet may be any light source, as long as it is a lamp that irradiates ultraviolet to near ultraviolet light. Examples thereof include low, high or ultra high pressure mercury lamps, metal halide lamps, (pulsed) xenon lamps, electrodeless lamps, and the like.

Here, as a method of selectively irradiating only the resin composition located in the light-shielding region with ultraviolet rays without irradiating the exposed region at the time of bonding, a method of shielding using an ultraviolet ray shielding plate is exemplified in the present embodiment, but the method of selectively irradiating the light-shielding region with ultraviolet rays is not limited to this method. For example, a method in which the light source of the ultraviolet irradiator is set to have the same shape as the light shielding portion, a method in which the light source is designed so as to be able to be condensed at a specific portion by an optical fiber and the condensed ultraviolet rays are scanned over the light shielding region (a method using a point light source UV), or the like can be applied without particular limitation as long as the light shielding region can be selectively cured. From the viewpoint of simplicity, a method using an ultraviolet shielding plate is more preferable.

In step 1, the irradiation of ultraviolet rays is performed from the upper side surface (the side opposite to the liquid crystal display cell side or the side opposite to the transparent substrate side as viewed from the ultraviolet curable resin composition) (generally, the surface on the atmosphere side) of the coating layer. The ultraviolet irradiation may be performed in the air, or may be performed in a vacuum or under reduced pressure or under non-reduced pressure depending on the purpose, and in the presence or absence of a curing-inhibiting gas such as oxygen or ozone. After the vacuum is formed according to the purpose, ultraviolet rays may be irradiated while spraying a curing-inhibiting gas or an inert gas onto the upper surface of the coating layer. When the resin composition in the light-shielding region is cured in the atmosphere, the side opposite to the liquid crystal display cell side or the side opposite to the transparent substrate side is the atmosphere side.

From the viewpoint of improving the adhesiveness by leaving the adhesiveness on the surface of the coating layer located in the light-shielding region, it is preferable to irradiate the upper surface of the coating layer with ultraviolet rays in the presence of air or a curing-inhibiting gas such as oxygen or ozone.

(step 2)

Next, as shown in fig. 1(b), the liquid crystal display unit 1 and the transparent substrate 2 having a light-shielding portion are bonded so that the coating layers 7 (coating layers of the ultraviolet curable resin composition in which the light-shielding regions are selectively cured at the time of bonding) are opposed to each other. The bonding may be performed under any conditions of atmosphere and vacuum.

Here, in order to prevent bubbles from being generated at the time of bonding, bonding is preferably performed in vacuum.

In this way, when the coating layer 7 of the ultraviolet curable resin composition cured in the light shielding region is provided on each of the liquid crystal display cell 1 and the transparent substrate 2 and then bonded, improvement in adhesion can be expected.

(step 3)

Next, as shown in fig. 1(c), the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with ultraviolet light 9 from the transparent substrate 2 side having a light shielding portion to cure the ultraviolet curable resin composition layer (coating layer).

The dose of ultraviolet irradiation in step 3 is preferably about 100mJ/cm²About 4000mJ/cm²Particularly preferably about 200mJ/cm²About 3000mJ/cm². The light source used for irradiation with ultraviolet to near ultraviolet light may be any light source, as long as it is a lamp that irradiates ultraviolet to near ultraviolet light. Examples thereof include low, high or ultra high pressure mercury lamps, metal halide lamps, (pulsed) xenon lamps, electrodeless lamps, and the like.

Thus, an optical member as shown in fig. 4 can be obtained.

(step 4)

Further, if necessary (step 4), the obtained optical member may be strongly bonded by applying pressure thereto.

When pressure is applied, the adhesive force of the cured product layer in the light-shielding region during bonding is improved. Accordingly, when the liquid crystal display unit 1 and the transparent substrate 2 are bonded to each other, an effect of preventing peeling due to external pressure or environmental change at the interface where the coating layers 7 are bonded to each other can be expected. In addition, the adhesive force of the resin cured layer 8 to the liquid crystal display unit 1 or the transparent substrate 2 having the light shielding portion is also stronger.

Therefore, it is preferable to go through step 4.

(second embodiment)

FIG. 2 is a process diagram showing a second embodiment of the method for producing an optical member using an ultraviolet curable resin composition of the present invention.

In addition, the same reference numerals are given to the same base material as the constituent base material in the first embodiment, and the description thereof will not be repeated here.

(step 1)

First, as shown in fig. 2(a), an ultraviolet curable resin composition is applied to the surface of the transparent substrate 2 having a light shielding portion, on which the light shielding portion 4 is provided. Then, the light-shielded region during bonding is irradiated with ultraviolet light to obtain a coating layer 7 of an ultraviolet-curable resin composition cured in the light-shielded region during bonding. Here, the exposed area at the time of bonding is covered by the ultraviolet shielding plate 6, and the resin composition in the exposed area is not cured when ultraviolet rays are irradiated.

(step 2)

Next, as shown in fig. 2(b), the liquid crystal display unit 1 and the transparent substrate 2 having a light shielding portion are bonded to each other so that the coating layer 7 of the transparent substrate 2 having a light shielding portion faces the display surface of the liquid crystal display unit 1. The bonding may be performed under any conditions of atmosphere and vacuum.

(step 3)

Next, as shown in fig. 2(c), the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with ultraviolet light 9 from the transparent substrate 2 side having a light shielding portion, and the ultraviolet curable resin composition in the exposure region at the time of bonding is cured.

Thus, an optical member as shown in fig. 4 can be obtained.

(third embodiment)

In addition to the first and second embodiments, the optical member of the present invention can be manufactured by applying the following modified third embodiment.

(step 1)

First, after applying an ultraviolet curable resin composition onto the display surface of the liquid crystal display cell 1, ultraviolet rays are irradiated to the light-shielded region during bonding to obtain a coating layer 7 of the ultraviolet curable resin composition after curing the light-shielded region during bonding. Here, the exposed area at the time of bonding is covered by the ultraviolet shielding plate 6, and the resin composition in the exposed area is not cured when ultraviolet rays are irradiated.

(step 2)

Next, the liquid crystal display unit 1 and the transparent substrate 2 having the light shielding portion are bonded so that the coating layer 7 of the liquid crystal display unit 1 faces the surface of the transparent substrate 2 having the light shielding portion, on which the light shielding portion 4 is provided. The bonding may be performed under any conditions of atmosphere and vacuum.

(step 3)

Next, the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with ultraviolet light 9 from the transparent substrate 2 side having a light shielding portion, and the ultraviolet curable resin composition in the exposure region at the time of bonding is cured.

Thus, the optical member shown in fig. 4 can be obtained.

(fourth embodiment)

In addition to the first, second, and third embodiments, the optical member of the present invention may be manufactured by a fourth embodiment modified as follows.

(step 1)

First, an ultraviolet curable resin composition is applied to the display surface of the liquid crystal display unit 1 and the surface of the transparent substrate 2 having a light shielding portion, on which the light shielding portion 4 is provided, respectively. Then, the light-shielded region during bonding was irradiated with ultraviolet light to obtain a coating layer 7 of an ultraviolet-curable resin composition after curing the light-shielded region during bonding. Here, by adding an acylphosphine oxide to the ultraviolet curable resin composition and adjusting the amount of ultraviolet irradiation, a cured layer having a cured portion present on the lower side of the coating layer 7 (the side of the liquid crystal display unit 1 or the transparent substrate 2 having a light shielding portion) and an uncured portion present on the upper side of the coating layer 7 (the side opposite to the side of the liquid crystal display unit 1 or the transparent substrate 2 having a light shielding portion) can be formed on the coating layer 7. On the other hand, the exposed region at the time of bonding is covered with the ultraviolet shielding plate 6, and the resin composition in the exposed region is not cured when ultraviolet rays are irradiated.

(step 2)

Next, the liquid crystal display unit 1 and the transparent substrate 2 having the light shielding portion are bonded so that the coating layers 7 face each other. The bonding may be performed under any conditions of atmosphere and vacuum.

(step 3)

Next, the optical member obtained by bonding the transparent substrate 2 and the liquid crystal display unit 1 is irradiated with ultraviolet light 9 from the transparent substrate 2 side having a light shielding portion, and the ultraviolet curable resin composition in the exposure region at the time of bonding is cured.

Thus, an optical member as shown in fig. 4 can be obtained.

The above embodiments have described several embodiments of the method for producing an optical member according to the present invention, with specific examples of optical substrates. In the manufacturing method of the present invention, various substrates described later may be used as the optical substrate instead of the liquid crystal display cell, or the various substrates described later may be used as the optical substrate instead of the transparent substrate.

In addition, as an optical substrate such as a liquid crystal display unit or a transparent substrate, a substrate obtained by further laminating another optical substrate layer (for example, a film or another optical substrate layer laminated with a cured product layer of an ultraviolet curable resin composition) on the above-mentioned various substrates can be used.

The method of applying the ultraviolet-curable resin composition, the film thickness of the cured resin, the dose and light source at the time of ultraviolet irradiation, the method of selectively irradiating the light-shielded region with ultraviolet light, the step of applying pressure to the optical member to strengthen adhesion, and the like described in the first embodiment are not limited to the above embodiments, and may be applied to any of the manufacturing methods included in the present invention.

Specific embodiments of the optical member that can be manufactured in the first to fourth embodiments, including the liquid crystal display unit, are shown below.

(i) The optical substrate having the light-shielding portion is at least one optical substrate selected from the group consisting of a transparent glass substrate having the light-shielding portion, a transparent resin substrate having the light-shielding portion, and a glass substrate on which the light-shielding portion and the transparent electrode are formed, the optical substrate to be bonded thereto is at least one display unit selected from the group consisting of a liquid crystal display unit, a plasma display unit, and an organic EL display unit, and the obtained optical member is a display unit provided with the optical substrate having the light-shielding portion.

(ii) One optical substrate is a protective substrate having a light-shielding portion, the other optical substrate bonded to the one optical substrate is a touch panel or a display unit having a touch panel, and an optical member formed by bonding at least two optical substrates is a touch panel having a protective substrate having a light-shielding portion or a display unit having the touch panel.

In this case, in step 1, it is preferable to coat the ultraviolet curable resin composition on either or both of the surface of the protective substrate having the light shielding portion on which the light shielding portion is provided and the touch surface of the touch panel.

(iii) One optical substrate is an optical substrate having a light shielding portion, the other optical substrate bonded thereto is a display unit, and an optical member in which at least two optical substrates are bonded is a display unit including an optical substrate having a light shielding portion.

In this case, in step 1, it is preferable to coat the ultraviolet curable resin composition on one or both of the surface of the optical substrate having the light shielding portion on the side where the light shielding portion is provided and the display surface of the display unit.

Specific examples of the optical substrate having a light shielding portion include a protective plate for a display screen having a light shielding portion, a touch panel provided with a protective substrate having a light shielding portion, and the like.

The surface of the optical substrate having the light-shielding portion on the side where the light-shielding portion is provided refers to, for example, a surface of the protective plate on the side where the light-shielding portion is provided when the optical substrate having the light-shielding portion is a protective plate for a display screen having the light-shielding portion. In addition, when the optical substrate having the light shielding portion is a touch panel including a protective substrate having the light shielding portion, since the surface having the light shielding portion of the protective substrate having the light shielding portion is bonded to the touch surface of the touch panel, the surface of the optical substrate having the light shielding portion on the side where the light shielding portion is provided is the substrate surface of the touch panel opposite to the touch surface of the touch panel.

The light-shielding portion of the optical substrate having the light-shielding portion may be located at any position of the optical substrate, and is generally formed in a frame shape around the transparent plate-like or sheet-like optical substrate, and has a width of about 0.5mm to about 10mm, preferably about 1mm to about 8mm, and more preferably about 2mm to about 8 mm.

Next, the ultraviolet curable resin composition will be described.

The ultraviolet-curable resin composition used in the method for producing an optical member of the present invention is not particularly limited as long as it is a resin that is cured by irradiation with ultraviolet rays, and an ultraviolet-curable resin composition containing a (meth) acrylate (a) and a photopolymerization initiator (B) (hereinafter, also referred to as "the ultraviolet-curable resin composition of the present invention") is preferably used. The ultraviolet-curable resin composition containing the (meth) acrylate (a) and the photopolymerization initiator (B) may contain, as optional components, other components that can be added to the ultraviolet-curable resin composition used in optical applications.

The phrase "can be added to an ultraviolet-curable resin composition used for optical applications" means that the ultraviolet-curable resin composition does not contain an additive which reduces the transparency of a cured product to such an extent that the ultraviolet-curable resin composition cannot be used for optical applications.

When a sheet of a cured product having a thickness of 200 μm after curing is produced from the ultraviolet-curable resin composition used in the present invention, the sheet preferably has an average transmittance of at least 90% under light having a wavelength of 400 to 800 nm.

The composition ratio of the ultraviolet curable resin composition is 25 to 90 wt% of (meth) acrylate (A), 0.2 to 5 wt% of photopolymerization initiator (B) and the balance of the other components, based on the total amount of the ultraviolet curable resin composition.

In the ultraviolet curable resin composition of the present invention, any of the photopolymerization initiators generally used can be used as the photopolymerization initiator (B).

The (meth) acrylate (a) in the ultraviolet curable resin composition is not particularly limited, and any one selected from the group consisting of urethane (meth) acrylates, (meth) acrylates having a polyisoprene skeleton, and (meth) acrylate monomers is preferably used. More preferably, the following two are contained: (i) at least either of a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton; and (ii) (meth) acrylate ester monomer.

In the present specification, "(meth) acrylate" means either one or both of methacrylate and acrylate. The same applies to "(meth) acrylic acid" and the like.

The (meth) acrylate monomer (ii) is used as a (meth) acrylate other than the (i).

The urethane (meth) acrylate is obtained by reacting a polyol, a polyisocyanate, and a hydroxyl group-containing (meth) acrylate.

Examples of the polyhydric alcohol include: alkylene glycols having 1 to 10 carbon atoms such as neopentyl glycol, 3-methyl-1, 5-pentanediol, ethylene glycol, propylene glycol, 1, 4-butanediol, and 1, 6-hexanediol; trihydric alcohols such as trimethylolpropane and pentaerythritol: alcohols having a cyclic skeleton such as dimethylol tricyclodecane and bis [ hydroxymethyl ] cyclohexane; and polyester polyols obtained by the reaction of the above polyols with polybasic acids (e.g., succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydrophthalic anhydride, etc.); caprolactone alcohol obtained by the reaction of a polyol with-caprolactone; polycarbonate polyols (e.g., polycarbonate diols obtained by reacting 1, 6-hexanediol with diphenyl carbonate); or polyether polyols (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide-modified bisphenol a, and the like), and the like.

The polyol is preferably polypropylene glycol from the viewpoint of compatibility with and adhesion to the other component (a), and polypropylene glycol having a weight average molecular weight of 2000 or more is particularly preferable from the viewpoint of adhesion between the substrate and the cured product layer or adhesion between the cured product layers. When polypropylene glycol having a weight average molecular weight of 2000 or more is used, the adhesion of the cured product layer is improved because the effect of preventing peeling at the interface between the coating layers 7 of the ultraviolet curable resin composition after curing the light-shielding region at the time of bonding due to external pressure or environmental change is improved when the liquid crystal display cell and the optical substrate such as a transparent substrate are bonded to each other. Further, the adhesive strength of the resin cured layer 8 to an optical base material such as the liquid crystal display unit 1 or the transparent substrate 2 having a light shielding portion is also improved.

The upper limit of the weight average molecular weight of the polypropylene glycol in this case is not particularly limited, but is preferably 10000 or less, and more preferably 5000 or less.

Examples of the organic polyisocyanate include: isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, xylene diisocyanate, diphenylmethane-4, 4' -diisocyanate, or tetrahydrodicyclopentadiene isocyanate, and the like.

As the hydroxyl group-containing (meth) acrylate, for example: hydroxy C2-C4 alkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; dimethylol cyclohexyl mono (meth) acrylate; hydroxy caprolactone (meth) acrylate; and hydroxyl-terminated polyalkylene glycol (meth) acrylates, and the like.

The above reaction for obtaining the urethane (meth) acrylate is carried out, for example, as follows. That is, the urethane oligomer is synthesized by mixing the polyol and the organic polyisocyanate so that 1 equivalent of the isocyanate group of the organic polyisocyanate to the hydroxyl group of the polyol is preferably 1.1 to 2.0 equivalents, more preferably 1.1 to 1.5 equivalents, and reacting the mixture at 70 to 90 ℃. Next, the obtained urethane oligomer and the hydroxyl group-containing (meth) acrylate are mixed so that the hydroxyl group of the hydroxyl group-containing (meth) acrylate is preferably 1 to 1.5 equivalents to 1 equivalent of the isocyanate group of the obtained urethane oligomer, and the mixture is reacted at 70 to 90 ℃.

The weight average molecular weight of the urethane (meth) acrylate is preferably from about 7000 to about 25000, more preferably from 10000 to 20000. When the weight average molecular weight is too small, shrinkage may become large, and when the weight average molecular weight is too large, curability may be deteriorated.

The urethane (meth) acrylate in the ultraviolet curable resin composition of the present invention may be used in 1 kind or 2 or more kinds. When 2 or more kinds are used, they may be mixed at an arbitrary ratio. The weight ratio of the urethane (meth) acrylate in the ultraviolet curable resin composition of the present invention is usually 20 to 80% by weight, preferably 30 to 70% by weight.

The (meth) acrylate having a polyisoprene skeleton is a compound having a (meth) acryloyl group at the end or in the side chain of a polyisoprene molecule. The (meth) acrylate having a polyisoprene skeleton is available, for example, in the form of "UC-203" (manufactured by clony corporation). The number average molecular weight of the (meth) acrylate having a polyisoprene skeleton in terms of polystyrene is preferably 10000 to 50000, more preferably about 25000 to about 45000.

The weight ratio of the (meth) acrylate having a polyisoprene skeleton in the ultraviolet-curable resin composition of the present invention is usually 20 to 80% by weight, preferably 30 to 70% by weight.

As the (meth) acrylate monomer, a (meth) acrylate having 1 (meth) acryloyl group in the molecule can be preferably used.

Here, the (meth) acrylate monomer means a (meth) acrylate other than the urethane (meth) acrylate, the epoxy (meth) acrylate, and the (meth) acrylate having a polyisoprene skeleton.

Specific examples of the (meth) acrylate having 1 (meth) acryloyl group in the molecule include: alkyl esters having 5 to 20 carbon atoms of (meth) acrylic acid such as isooctyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) acrylate, cetyl (meth) acrylate, isomyristyl (meth) acrylate, and tridecyl (meth) acrylate; benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acryloylmorpholine, phenylglycidyl (meth) acrylate, tricyclodecane (meth) acrylate, dihydrodicyclopentadienyl oxyethyl (meth) acrylate, isobornyl (meth) acrylate, (meth) acrylates having a cyclic structure, preferably a C4-C10 cyclic structure, such as tetrahydrodicyclopentadiene acrylate, 1-adamantane acrylate, 2-methyl-2-adamantane acrylate, 2-ethyl-2-adamantane acrylate, 1-adamantane methacrylate, polypropylene oxide-modified nonylphenyl (meth) acrylate, and dihydrodicyclopentadiene oxyethyl (meth) acrylate; alkyl esters having 1 to 5 carbon atoms and having a hydroxyl group in (meth) acrylic acid, such as 2-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; polyalkylene glycol (meth) acrylates such as ethoxydiethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, and polypropylene oxide-modified nonylphenyl (meth) acrylate; and phosphoric acid (meth) acrylates such as ethylene oxide-modified phenoxyated phosphoric acid (meth) acrylate, ethylene oxide-modified butoxylated phosphoric acid (meth) acrylate, and ethylene oxide-modified octyloxylated phosphoric acid (meth) acrylate, and preferred examples thereof include ethylene oxide-modified C4 to C10 alkoxylated or phenoxyated phosphoric acid (meth) acrylates.

Among the (meth) acrylates having 1 (meth) acryloyl group in the molecule, preferred are compounds selected from the group consisting of alkyl esters having 10 to 20 carbon atoms of (meth) acrylic acid, 2-ethylhexyl carbitol acrylate, acryloylmorpholine, 4-hydroxybutyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isostearyl (meth) acrylate, dihydrodicyclopentadienyloxyethyl (meth) acrylate, and polypropylene oxide-modified nonylphenyl (meth) acrylate. In particular, from the viewpoint of flexibility of the resin, it is preferable to use a compound selected from the group consisting of an alkyl ester having 10 to 20 carbon atoms of (meth) acrylic acid, dihydrodicyclopentadienyloxyethyl (meth) acrylate, a polypropylene oxide-modified nonylphenyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate, more preferably an alkyl ester having 10 to 20 carbon atoms of (meth) acrylic acid, and still more preferably lauryl (meth) acrylate.

On the other hand, from the viewpoint of improving adhesion to glass, the (meth) acrylate monomer is preferably at least one of an alkyl ester of (meth) acrylic acid having 1 to 5 carbon atoms and acryloylmorpholine, and particularly preferably acryloylmorpholine.

The (meth) acrylate monomer preferably contains both an alkyl ester having 10 to 20 carbon atoms of (meth) acrylic acid and an alkyl ester having 1 to 5 carbon atoms and acryloyl morpholine, each having a hydroxyl group of (meth) acrylic acid, and more preferably contains both lauryl (meth) acrylate and acryloyl morpholine.

The composition of the present invention may contain a polyfunctional (meth) acrylate monomer other than a (meth) acrylate having 1 (meth) acryloyl group within a range not impairing the characteristics of the present invention.

Specific examples thereof include: bifunctional (meth) acrylates such as tricyclodecane dimethanol di (meth) acrylate, dioxane diol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, alkylene oxide-modified bisphenol a type di (meth) acrylate, caprolactone-modified hydroxypivalic acid neopentyl glycol di (meth) acrylate, and ethylene oxide-modified phosphoric acid di (meth) acrylate; trifunctional (meth) acrylates such as trimethylolpropane C2 to C10 alkane tri (meth) acrylate such as trimethylolpropane tri (meth) acrylate or trimethylolpropane octane tri (meth) acrylate, trimethylolpropane polyalkoxy tri (meth) acrylate such as trimethylolpropane polyethoxy tri (meth) acrylate or trimethylolpropane polyethoxy polypropoxy tri (meth) acrylate, trimethylolpropane polyalkoxy tri (meth) acrylate such as trimethylolpropane C2 to C10 alkane polyalkoxy tri (meth) acrylate, tris [ (meth) acryloyloxyethyl ] isocyanurate, pentaerythritol tri (meth) acrylate, and alkylene oxide-modified trimethylolpropane tri (meth) acrylate such as ethylene oxide-modified trimethylolpropane tri (meth) acrylate and propylene oxide-modified trimethylolpropane tri (meth) acrylate; and tetrafunctional or higher (meth) acrylates such as pentaerythritol polyethoxy tetra (meth) acrylate, pentaerythritol polypropoxy tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

In the present invention, when the above-mentioned polyfunctional (meth) acrylate is used in combination, a bifunctional (meth) acrylate is preferably used in order to suppress curing shrinkage.

In the ultraviolet curable resin composition of the present invention, 1 or 2 or more of these (meth) acrylate monomer components may be used. When 2 or more kinds are used, they may be mixed at an arbitrary ratio. The weight ratio of the (meth) acrylate monomer in the ultraviolet curable resin composition of the present invention is usually 5 to 70% by weight, preferably 10 to 50% by weight. When the amount is less than 5% by weight, curability may be poor, and when the amount is more than 70% by weight, shrinkage may be large.

In the embodiment of the ultraviolet curable resin composition containing both (i) at least one of a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (ii) a (meth) acrylate monomer, the total content of both (i) and (ii) is usually 25 to 90% by weight, preferably 40 to 90% by weight, and more preferably 40 to 80% by weight, based on the total amount of the resin composition.

In the present invention, from the viewpoint of excellent adhesion after curing of the coating layer of the ultraviolet curable resin composition which is selectively cured in the light-shielding region obtained in step 1 and is not cured in the other part, and also in terms of imparting strong adhesion at the interface at the time of bonding, it is particularly preferable to use a (meth) acrylate having a polypropyleneoxy structure as the (meth) acrylate (a). When the (meth) acrylate having a polytrimethylene oxide structure is used, the adhesion of the cured product layer is improved because the effect of preventing peeling at the interface between the coating layers 7 of the ultraviolet curable resin composition after curing the light-shielding region at the time of bonding due to external pressure or environmental change is improved when the liquid crystal display cell is bonded to an optical substrate such as a transparent substrate. Further, the adhesive strength of the resin cured layer 8 to an optical base material such as the liquid crystal display unit 1 or the transparent substrate 2 having a light shielding portion is also improved.

Among the (meth) acrylates (a), the (meth) acrylate having a polypropyleneoxy structure includes urethane (meth) acrylate having a polypropyleneoxy structure and a (meth) acrylate monomer having a polypropyleneoxy structure.

In the ultraviolet curable resin composition of the present invention, a urethane (meth) acrylate having a polypropyleneoxy structure is more preferably contained as the (meth) acrylate (a).

Specific examples of the urethane (meth) acrylate having a polypropyleneoxy structure include urethane (meth) acrylates obtained by reacting three components, namely polypropylene glycol, polyisocyanate and hydroxyl group-containing (meth) acrylate.

Specific examples of the (meth) acrylate monomer having a polypropyleneoxy structure include: polypropylene glycol (meth) acrylate, polypropylene oxide-modified nonylphenyl (meth) acrylate, polypropylene glycol di (meth) acrylate, and propylene oxide-modified trimethylolpropane tri (meth) acrylate.

In the ultraviolet curable resin composition of the present invention, an epoxy (meth) acrylate may be used as the (meth) acrylate (a) within a range not impairing the characteristics of the present invention.

Epoxy (meth) acrylates have the function of improving curability and increasing the hardness and curing speed of cured products. As the epoxy (meth) acrylate, any epoxy (meth) acrylate obtained by reacting a glycidyl ether type epoxy compound with (meth) acrylic acid can be used.

As the glycidyl ether type epoxy compound for obtaining an epoxy (meth) acrylate which is preferably used, there can be mentioned: diglycidyl ether of bisphenol a or an alkylene oxide adduct thereof, diglycidyl ether of bisphenol F or an alkylene oxide adduct thereof, diglycidyl ether of hydrogenated bisphenol a or an alkylene oxide adduct thereof, diglycidyl ether of hydrogenated bisphenol F or an alkylene oxide adduct thereof, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanedimethanol diglycidyl ether, polypropylene glycol diglycidyl ether, and the like.

Epoxy (meth) acrylates can be obtained by reacting these glycidyl ether type epoxy compounds with (meth) acrylic acid under the conditions described below.

The glycidyl ether epoxy compound is reacted with (meth) acrylic acid in a ratio of 0.9 to 1.5 mol, preferably 0.95 to 1.1 mol, based on 1 equivalent of the epoxy group of the glycidyl ether epoxy compound. The reaction temperature is preferably 80 to 120 ℃ and the reaction time is about 10 to 35 hours. To promote the reaction, catalysts such as triphenylphosphine, TAP, triethanolamine, and tetraethylammonium chloride are preferably used. In addition, p-methoxyphenol, methylhydroquinone, and the like may be used as a polymerization inhibitor for preventing polymerization during the reaction.

As the epoxy (meth) acrylate which can be preferably used in the present invention, bisphenol a type epoxy (meth) acrylate obtained from a bisphenol a type epoxy compound is exemplified. The epoxy (meth) acrylate that can be used in the present invention preferably has a weight average molecular weight of 500 to 10000.

The weight ratio of the epoxy (meth) acrylate in the ultraviolet curable resin composition of the present invention is usually 1 to 80% by weight, preferably 5 to 30% by weight.

The content of the (meth) acrylate (a) in the ultraviolet curable resin composition of the present invention is 25 to 90% by weight, preferably 40 to 90% by weight, and more preferably 40 to 80% by weight, based on the total amount of the ultraviolet curable resin composition.

The ultraviolet curable resin composition of the present invention is more preferably the following: preferably, at least one selected from the group consisting of the urethane (meth) acrylate, the (meth) acrylate having a polyisoprene skeleton, and the (meth) acrylate monomer is contained as the (meth) acrylate (a); the content of the urethane (meth) acrylate is 20 to 80 wt%, preferably 30 to 70 wt%; the content ratio of the (meth) acrylate having a polyisoprene skeleton is 20 to 80% by weight, preferably 30 to 70% by weight; the content of the (meth) acrylate monomer is 5 to 70% by weight, preferably 10 to 50% by weight.

The ultraviolet curable resin composition of the present invention is preferably further characterized by: the urethane (meth) acrylate or the (meth) acrylate having a polyisoprene skeleton is contained in an amount of 20 to 80 wt%, preferably 30 to 70 wt%, and the (meth) acrylate monomer is contained in an amount of 5 to 70 wt%, preferably 10 to 50 wt%, as the (meth) acrylate (A).

As the photopolymerization initiator (B) contained in the ultraviolet curable resin composition of the present invention, any known photopolymerization initiator can be used.

Specific examples of the photopolymerization initiator (B) include: 1-hydroxycyclohexyl phenyl ketone (イルガキュア (registered trademark, the same applies hereinafter) 184; manufactured by BASF Co., Ltd.), 2-hydroxy-2-methyl [4- (1-methylvinyl) phenyl ] propanol oligomer (エサキュア ONE; manufactured by Ningceddi Co., Ltd.), 1- [4- (2-hydroxyethoxy) phenyl ] -2-hydroxy-2-methyl-1-propan-1-ONE (イルガキュア 2959; manufactured by BASF Co., Ltd.), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl ] phenyl } -2-methylpropan-1-ONE (イルガキュア 127; manufactured by BASF Co., Ltd.), 2-dimethoxy-2-phenylacetophenone (イルガキュア 651; manufactured by BASF Co., Ltd.) 2-hydroxy-2-methyl-1-phenylpropan-1-one (ダロキュア (registered trademark) 1173; manufactured by BASF Co.), 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one (イルガキュア 907; manufactured by BASF Co.), a mixture of 2- [ 2-oxo-2-phenylacetyloxyethoxy ] ethyl oxyphenyl acetate and 2- [ 2-hydroxyethoxy ] ethyl oxyphenyl acetate (イルガキュア 754; manufactured by BASF Co.), 2-benzyl-2-dimethylamino-1- (4- (N-morpholino) phenyl) butan-1-one, 2-chlorothioxanthone, and a pharmaceutically acceptable salt thereof, 2, 4-dimethylthioxanthone, 2, 4-diisopropylthioxanthone, isopropylthioxanthone, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 2,4, 6-trimethylbenzoylphenylethoxyphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2,4, 4-trimethylpentylphosphine oxide and the like.

When the coated ultraviolet-curable resin composition is selectively irradiated with ultraviolet light in the light-shielded region, it is preferable to use an acylphosphine oxide compound such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide in order to obtain a cured product layer having a cured portion present on the optical substrate side and an uncured portion present on the side opposite to the optical substrate side. Among them, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide is particularly preferable as the photopolymerization initiator (B) from the viewpoints of easiness of forming an uncured portion and transparency of a resin cured layer. In the case where the cured coating layer 7 of the ultraviolet curable resin composition after curing in the light-shielding region during the bonding is a cured layer having a cured portion existing on the optical substrate side and an uncured portion existing on the side opposite to the optical substrate side, the ultraviolet irradiation amount in step 1 is preferably 5 to 200mJ/cm²Particularly preferably 10 to 100mJ/cm²。

In the ultraviolet curable resin composition of the present invention, 1 or 2 or more kinds of the photopolymerization initiators (B) may be used. When 2 or more kinds are used, they may be mixed at an arbitrary ratio. The proportion by weight of the photopolymerization initiator (B) in the ultraviolet-curable resin composition of the present invention is usually 0.2 to 5% by weight, preferably 0.3 to 3% by weight. When the amount is within this range, the transparency is good and the curability is also good. If the amount is too large, the transparency of the cured resin layer may be deteriorated. When the photopolymerization initiator (B) is too small, the degree of curing of the resin composition is insufficient.

The ultraviolet curable resin composition of the present invention may contain, as other components, the following photopolymerization initiation aid, the compound having a structure represented by general formula (1) described below, the following softening component, the following additives, and the like, in addition to the (meth) acrylate (a) and the photopolymerization initiator (B). The content ratio of the other component to the total amount of the ultraviolet curable resin composition of the present invention is the remaining part obtained by subtracting the total amount of the (meth) acrylate (a) and the photopolymerization initiator (B) from the total amount. Specifically, the amount of the other components is about 0 to about 74.8 wt%, preferably about 5 to about 70 wt%, based on the total amount of the ultraviolet curable resin composition of the present invention.

In the ultraviolet curable resin composition of the present invention, an amine or the like which can be a photopolymerization initiation aid as one of the other components may be used in combination with the photopolymerization initiator (B). Examples of amines that can be used include: 2-dimethylaminoethyl benzoate, dimethylamino acetophenone, ethyl p-dimethylaminobenzoate or isoamyl p-dimethylaminobenzoate, etc. When the photopolymerization initiation assistant such as amine is used, the content thereof in the ultraviolet-curable resin composition of the present invention is usually 0.005 to 5% by weight, preferably 0.01 to 3% by weight.

The ultraviolet-curable resin composition of the present invention may contain a compound having a structure represented by the general formula (1) as needed.

(wherein n represents an integer of 0 to 40, m represents an integer of 10 to 50, R¹And R²May be the same or different. R¹And R²Alkyl having 1 to 18 carbon atoms, alkenyl having 1 to 18 carbon atoms, alkynyl having 1 to 18 carbon atoms, aryl having 5 to 18 carbon atoms).

The compound having a structure represented by the general formula (1) can be obtained, for example, in the form of ユニセーフ PKA-5017 (product name, polyethylene glycol polypropylene glycol allyl butyl ether) manufactured by Nichigan corporation, or the like.

When the compound having the structure represented by the general formula (1) is used, the weight ratio thereof in the ultraviolet curable resin composition is usually 10 to 80% by weight, preferably 10 to 70% by weight.

In the ultraviolet-curable resin composition of the present invention, softening components other than those described above may be used as necessary. As the other softening component in the present invention, a known softening component and a plasticizer which are generally used in the ultraviolet curable resin can be used. Specific examples of the softening component that can be used include: polymers or oligomers other than the above (meth) acrylic acid esters or the above compounds having a structure represented by the general formula (1), phthalic acid esters, phosphoric acid esters, glycol esters, citric acid esters, aliphatic dibasic acid esters, fatty acid esters, epoxy plasticizers, castor oils, terpene-based hydrogenated resins, and the like. Examples of the above-mentioned polymer or oligomer include: the polymer or oligomer having a polyisoprene skeleton, a polybutadiene skeleton or a xylene skeleton and an esterified product thereof are preferably used, and in some cases, the polymer or oligomer having a polybutadiene skeleton and an esterified product thereof are preferably used. Specific examples of the polymer or oligomer having a polybutadiene skeleton and the esterified product thereof include: butadiene homopolymer, epoxy-modified polybutadiene, butadiene-styrene random copolymer, maleic acid-modified polybutadiene, and terminal hydroxyl-modified liquid polybutadiene.

When the softening component is used, the weight ratio of the softening component in the ultraviolet curable resin composition is usually 10 to 80% by weight, preferably 10 to 70% by weight.

The ultraviolet-curable resin composition of the present invention may contain additives such as an antioxidant, an organic solvent, a coupling agent, a polymerization inhibitor, a leveling agent, an antistatic agent, a surface lubricant, a fluorescent whitening agent, a light stabilizer (e.g., a hindered amine compound), and a filler, as required.

Specific examples of the antioxidant include: BHT, 2, 4-bis (n-octylthio) -6- (4-hydroxy-3, 5-di-tert-butylanilino) -1,3, 5-triazine, pentaerythrityl tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2-thiodiethylene bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], triethylene glycol bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate ], 1, 6-hexanediol bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate ], octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, and mixtures thereof, N, N-hexamethylenebis (3, 5-di-tert-butyl-4-hydroxyhydrocinnamamide), 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3, 5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, octylated diphenylamine, 2, 4-bis [ (octylthio) methyl ] o-cresol, isooctyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], dibutylhydroxytoluene, and the like.

Specific examples of the organic solvent include: alcohols such as methanol, ethanol and isopropanol; dimethyl sulfone, dimethyl sulfoxide, tetrahydrofuran, dioxane, toluene, xylene, and the like.

As the coupling agent, there may be mentioned: silane coupling agents, titanium-containing coupling agents, zirconium-containing coupling agents, aluminum-containing coupling agents, and the like.

Specific examples of the silane coupling agent include: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, gamma-mercaptopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, N- (2- (vinylbenzylamino) ethyl) 3-aminopropyltrimethoxysilane hydrochloride, 3-methacryloxypropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, and 3-chloropropyltrimethoxysilane.

Specific examples of the titanium-containing coupling agent include: isopropyl (N-ethylamino) titanate, isopropyl triisostearoyl titanate, bis (dioctyl pyrophosphate) oxotitanium acetate, tetraisopropyl bis (dioctyl phosphite) titanate, neoalkoxytris (p-N- (. beta. -aminoethyl) aminophenyl) titanate, and the like.

Specific examples of the zirconium-containing coupling agent and the aluminum-containing coupling agent include: zirconium acetylacetonate, zirconium methacrylate, zirconium propionate, neoalkoxy zirconate, neoalkoxy trineodecanoyl zirconate, neoalkoxy tri (dodecanoyl) benzenesulfonyl zirconate, neoalkoxy tri (ethylenediamino ethyl) zirconate, neoalkoxy tri (meta-aminophenyl) zirconate, ammonium zirconium carbonate, aluminum acetylacetonate, aluminum methacrylate, aluminum propionate, and the like.

Specific examples of the polymerization inhibitor include: p-methoxyphenol, and methylhydroquinone.

Specific examples of the light stabilizer include: 1,2,2,6, 6-pentamethyl-4-piperidinol, 2,2,6, 6-tetramethyl-4-piperidinol, 1,2,2,6, 6-pentamethyl-4-piperidino (meth) acrylate (manufactured by Idiaceae, product name LA-82), tetrakis (1,2,2,6, 6-pentamethyl-4-piperidinyl) 1,2,3, 4-butanetetracarboxylic acid, tetrakis (2,2,6, 6-tetramethyl-4-piperidinyl) 1,2,3, 4-butanetetracarboxylic acid, 1,2,2,6, 6-pentamethyl-4-piperidinol and 3, 9-bis (2-hydroxy-1, 1-dimethylethyl) -2, a mixed esterified product of 4,8, 10-tetraoxaspiro [5.5] undecane, bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (1-undecyloxy-2, 2,6, 6-tetramethylpiperidin-4-yl) carbonate, 2,2,6, 6-tetramethyl-4-piperidyl methacrylate, bis (2,2,6, 6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate, 4-benzoyloxy-2, 2,6, 6-tetramethylpiperidine, 1- [2- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] ethyl ] -4- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] -2,2,6, 6-tetramethylpiperidine, 1,2,2,6, 6-pentamethyl-4-piperidyl (meth) acrylate, bis (1,2,2,6, 6-pentamethyl-4-piperidyl) [ [3, 5-bis (1, 1-dimethylethyl) -4-hydroxyphenyl ] methyl ] butylmalonate, bis (2,2,6, 6-tetramethyl-1 (octyloxy) -4-piperidyl) sebacate, reaction product of 1, 1-dimethylethylhydroperoxide and octane, N ', N' ', N' '' -tetrakis (4, 6-bis (butyl (N-methyl-2, 2,6, 6-tetramethylpiperidin-4-yl) amino) triazin-2-yl) -4, 7-diazepane-1, 10-diamine, dibutylamine-1, 3, 5-triazine-N, N' -bis (2,2,6, 6-tetramethyl-4-piperidyl-1, 6-hexamethylenediamine polycondensate with N- (2,2,6, 6-tetramethyl-4-piperidyl) butylamine, poly [ [6- (1,1,3, 3-tetramethylbutyl) amino-1, 3, 5-triazine-2, 4-diyl ] [ (2,2,6, 6-tetramethyl-4-piperidyl) imino ] hexamethylene [ (2,2,6, 6-tetramethyl-4-piperidyl) imino ] ], dimethyl succinate and 4-hydroxy-2, polymers of 2,6, 6-tetramethyl-1-piperidineethanol, 2,4, 4-tetramethyl-20- (. beta. -lauryloxycarbonyl) ethyl-7-oxa-3, 20-diazadispiro [5.1.11.2] heneicosane-21-one, beta-alanine N, - (2,2,6, 6-tetramethyl-4-piperidinyl) dodecane ester/tetradecyl ester, N-acetyl-3-dodecyl-1- (2,2,6, 6-tetramethyl-4-piperidinyl) pyrrolidine-2, 5-dione, 2,4, 4-tetramethyl-7-oxa-3, 20-diazadispiro [5,1,11,2] heneicosane-21-one, 2,2,4, 4-tetramethyl-21-oxa-3, 20-diazabicyclo [5,1,11,2] heneicosane-20-propanoic acid dodecyl/tetradecyl ester, malonic acid [ (4-methoxyphenyl) methylene ] bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) ester, higher fatty acid ester of 2,2,6, 6-tetramethyl-4-piperidinol, hindered amine compound such as N, N' -bis (2,2,6, 6-tetramethyl-4-piperidinyl) -1, 3-benzenedicarboxamide, benzophenone compound such as octophenone, 2- (2H-benzotriazol-2-yl) -4- (1,1,3, 3-tetramethylbutyl) phenol, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- [ 2-hydroxy-3- (3,4,5, 6-tetrahydrophthalimido-methyl) -5-methylphenyl ] benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3, 5-di-tert-amylphenyl) benzotriazole, the reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol, 2- (2H-benzotriazol-2-yl) -6-dodecyl-4- Benzotriazoles such as cresol, benzoates such as 2, 4-di-tert-butylphenyl-3, 5-di-tert-butyl-4-hydroxybenzoate, and triazines such as 2- (4, 6-diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy ] phenol. Particularly preferred light stabilizers are hindered amine compounds.

Specific examples of the filler include: and powders such as crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, zirconia, forsterite, steatite, spinel, titanium dioxide, and talc, and beads obtained by spheroidizing these powders.

The content of the additive added as needed to the total amount of the ultraviolet curable resin composition is about 0 wt% to about 3 wt% based on the total amount of the additive. When various additives are used, the content of the various additives is 0.01 to 3% by weight, preferably 0.01 to 1% by weight, and more preferably 0.02 to 0.5% by weight, based on the total weight of the composition.

The ultraviolet curable resin composition of the present invention can be obtained by mixing and dissolving the (meth) acrylate (a), the photopolymerization initiator (B), and the optional other components at room temperature to 80 ℃. Further, if necessary, the inclusions may be removed by filtration or the like.

In view of coatability, the ultraviolet-curable resin composition of the present invention is preferably prepared by appropriately adjusting the compounding ratio of the components so that the viscosity at 25 ℃ is in the range of 300 to 15000 mPas.

The cure shrinkage of the cured product of the ultraviolet curable resin composition of the present invention is preferably 3.0% or less, and particularly preferably 2.0% or less. Thus, when the ultraviolet curable resin composition is cured, the internal stress accumulated in the cured resin can be reduced, and the occurrence of strain at the interface between the substrate and the layer formed from the cured product of the ultraviolet curable resin composition can be effectively prevented.

In addition, when a substrate such as glass is thin, warpage during curing becomes large when the cure shrinkage ratio is large, and thus, the display performance is greatly adversely affected. From this viewpoint, it is also preferable that the curing shrinkage is small.

The cured product of the ultraviolet curable resin composition of the present invention preferably has a transmittance of 90% or more in a wavelength region of 400nm to 800nm when formed into a film having a thickness of 200 μm. This is because if the transmittance is less than 90%, light is difficult to transmit, and when the cured product is used in a display device, visibility of a display image may be reduced.

Further, when the cured product has a high transmittance in the wavelength region of 400 to 450nm, it is expected that the visibility of a displayed image is further improved. Therefore, when the cured product is formed into the film, the transmittance in the wavelength region of 400 to 450nm is preferably 90% or more.

The ultraviolet curable resin composition containing the (meth) acrylate (a) and the photopolymerization initiator (B) used in the production method of the present invention is described in some preferred embodiments below. "wt%" in the content of each component represents a content ratio with respect to the total amount of the ultraviolet curable resin composition of the present invention.

(I) An ultraviolet-curable resin composition containing a (meth) acrylate (A) and a photopolymerization initiator (B), wherein the (meth) acrylate (A) is at least one (meth) acrylate selected from the group consisting of urethane (meth) acrylates, (meth) acrylates having a polyisoprene skeleton, and (meth) acrylate monomers.

(II) the ultraviolet-curable resin composition according to the above (I), which comprises both (I) a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (II) a (meth) acrylate monomer as the (meth) acrylate (A).

(III) the ultraviolet-curable resin composition according to the above (I) or (II), wherein the urethane (meth) acrylate or the (meth) acrylate monomer is a urethane (meth) acrylate having a polypropyleneoxy structure or a (meth) acrylate monomer having a polypropyleneoxy structure.

(IV) the ultraviolet curable resin composition according to (I) or (II), wherein the urethane (meth) acrylate is a urethane (meth) acrylate obtained by reacting three components, namely polypropylene glycol, a polyisocyanate and a hydroxyl group-containing (meth) acrylate.

(V) the ultraviolet-curable resin composition according to any one of the above (I) to (IV), wherein the weight-average molecular weight of the urethane (meth) acrylate is 7000 to 25000, and the number-average molecular weight of the (meth) acrylate having a polyisoprene skeleton is 15000 to 50000.

(VI) an ultraviolet-curable resin composition containing a (meth) acrylate (A) and a photopolymerization initiator (B) and containing 2,4, 6-trimethylbenzoyldiphenylphosphine oxide as the photopolymerization initiator (B), or an ultraviolet-curable resin composition according to any one of the above-mentioned items (I) to (V) containing 2,4, 6-trimethylbenzoyldiphenylphosphine oxide as the photopolymerization initiator (B).

(VII) an ultraviolet-curable resin composition containing a (meth) acrylate (A) and a photopolymerization initiator (B) and further containing other components in addition to the components (A) and (B), or any of the ultraviolet-curable resin compositions described in the above (I) to (VI) containing other components in addition to the components (A) and (B).

(VIII) the ultraviolet-curable resin composition according to the above (VII), wherein the content of the (meth) acrylate (A) is 25 to 90% by weight, the content of the photopolymerization initiator (B) is 0.2 to 5% by weight, and the other components are the remainder.

(IX) the ultraviolet-curable resin composition according to the above (VIII), which comprises 20 to 80% by weight of (i) at least one of urethane (meth) acrylate and polyisoprene (meth) acrylate and 5 to 70% by weight of (ii) a (meth) acrylate monomer as the (meth) acrylate (A), and the total content of both is 40 to 90% by weight.

(X) the ultraviolet-curable resin composition according to any one of the above (VII) to (IX), wherein the compound represented by the general formula (1) is contained in an amount of 10 to 80% by weight as another component.

(XI) an ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B), or an ultraviolet-curable resin composition as described in any one of the above (I) to (X), wherein the curing shrinkage of a cured product of the ultraviolet-curable resin composition is 3% or less.

(XII) an ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B), or an ultraviolet-curable resin composition as described in any of (I) to (XI), wherein a sheet comprising a cured product of the ultraviolet-curable resin composition having a film thickness of 200 μm has an average transmittance of at least 90% in a wavelength region of 400 to 450nm and an average transmittance of at least 90% in a wavelength region of 400 to 800 nm.

The ultraviolet curable resin composition of the present invention can be suitably used as an adhesive for producing an optical member by bonding a plurality of optical substrates through the steps including the above-described steps 1 to 3 and optional step 4.

Examples of the optical base material used in the method for producing an optical member of the present invention include a transparent plate, a sheet, a touch panel, and a display unit.

In the present specification, the term "optical substrate" refers to both an optical substrate having no light-shielding portion on the surface and an optical substrate having a light-shielding portion on the surface. In the method for producing an optical member according to the present invention, at least one of the plurality of optical substrates used is an optical substrate having a light shielding portion.

The optical substrate having a light-shielding portion is not particularly limited as long as the light-shielding portion is formed on the surface of the optical substrate made of the above material. The position of the light-shielding portion on the optical substrate having the light-shielding portion is not particularly limited. A preferable embodiment is a case where a strip-shaped light-shielding portion having a width of 0.05 to 20mm, preferably about 0.05 to about 10mm, and more preferably about 0.1 to about 6mm is provided in the peripheral portion of the optical substrate. The light-shielding portion on the optical substrate can be formed by attaching a tape, applying paint, printing, or the like.

In the method for producing an optical member according to the present invention, the optical substrate to be bonded to the optical substrate having the light-shielding portion may be an optical substrate having a light-shielding portion on a surface thereof, or an optical substrate having no light-shielding portion.

As a material of the optical substrate used in the present invention, various materials can be used. Specifically, there may be mentioned: PET, PC, PMMA, a composite of PC and PMMA, glass, COC, COP, acrylic resin and other resins. As the optical substrate used in the present invention, for example, a transparent plate or sheet, there can be used: a transparent plate or sheet obtained by laminating a plurality of films or sheets such as a polarizing plate; an unstacked transparent sheet or sheet; and transparent plates made of inorganic glass (inorganic glass plates and processed products thereof, such as lenses, prisms, ITO glass), and the like.

The optical substrate used in the present invention includes, in addition to the polarizing plate and the like described above, a laminate (hereinafter, also referred to as "functional laminate") including a plurality of functional plates or sheets, such as a touch panel (touch panel input sensor) or a display unit described below.

As the sheet that can be used as the optical substrate used in the present invention, there can be mentioned: icon sheet, decorative sheet, and protective sheet. As the plate (transparent plate) that can be used in the method for producing an optical member of the present invention, a decorative plate and a protective plate can be cited. As the material of these sheets or plates, the materials listed as the material of the transparent plate or sheet can be applied.

The surface material of the touch panel that can be used as the optical substrate used in the present invention includes: glass, PET, PC, PMMA, composites of PC and PMMA, COC and COP.

The thickness of the plate-like or sheet-like optical substrate such as a transparent plate or sheet is not particularly limited, but is usually about 5 μm to about 5cm, preferably about 10 μm to about 10mm, and more preferably about 50 μm to about 3 mm.

A preferable optical member obtained by the production method of the present invention is an optical member obtained by laminating a plate-like or sheet-like transparent optical substrate having a light-shielding portion and the functional laminate with a cured product of the ultraviolet curable resin composition of the present invention.

In the manufacturing method of the present invention, a display unit (hereinafter also referred to as a display panel) with an optically functional material can be manufactured by using the display unit such as a liquid crystal display device as one optical base material and using the optically functional material having a light shielding portion as another optical base material. Examples of the display unit include: a display device such as an LCD, an organic or inorganic EL display, an EL lighting, an electronic paper, and a plasma display, which is formed by bonding a polarizing plate to glass. Further, examples of the optical functional material include: transparent plastic plates such as acrylic resin plates, PC plates, PET plates, and PEN plates, tempered glass, and touch panels.

When the ultraviolet curable resin composition of the present invention is used as an adhesive for bonding optical substrates, the refractive index of the cured product is preferably 1.45 to 1.55, because the visibility of a displayed image is further improved.

When the refractive index of the cured product is within this range, the difference in refractive index from the substrate used as the optical substrate can be reduced, and diffuse reflection of light can be suppressed to reduce optical loss.

Preferred embodiments of the optical member obtained by the production method of the present invention include the following (i) to (vii).

(i) An optical member obtained by laminating an optical substrate having a light-shielding portion and the functional laminate using a cured product of the ultraviolet curable resin composition of the present invention.

(ii) The optical member according to the above (i), wherein the optical substrate having a light-shielding portion is an optical substrate selected from the group consisting of a transparent glass substrate having a light-shielding portion, a transparent resin substrate having a light-shielding portion, and a glass substrate on which a light-shielding portion and a transparent electrode are formed, and the functional laminate is a display unit or a touch panel.

(iii) The optical member according to the above (ii), wherein the display unit is any one of a liquid crystal display unit, a plasma display unit and an organic EL display unit.

(iv) A touch panel (or touch panel input sensor) obtained by bonding a plate-like or sheet-like optical base material having a light-shielding portion to the surface of the touch panel on the touch surface side using a cured product of the ultraviolet-curable resin composition of the present invention.

(v) A display panel obtained by laminating a plate-like or sheet-like optical substrate having a light-shielding portion on a display screen of a display unit using a cured product of the ultraviolet curable resin composition of the present invention.

(vi) The display panel according to the above (v), wherein the plate-like or sheet-like optical base material having the light shielding portion is a touch panel or a protective base material for protecting a display screen of the display unit.

(vii) The optical member, touch panel, or display panel according to any one of (I) to (vi) above, wherein the ultraviolet curable resin composition is the ultraviolet curable resin composition according to any one of (I) to (XII) above.

The optical member of the present invention can be obtained by bonding a plurality of optical substrates selected from the optical substrates by the method of the above steps 1 to 3 and optionally step 4 using the ultraviolet curable resin composition of the present invention. In the step 1, the ultraviolet curable resin composition may be applied to only one of the surfaces of the two optical substrates to be bonded to each other with the cured product layer interposed therebetween, or may be applied to both surfaces.

For example, in the case where the functional laminate is the optical member described in (ii) above of a touch panel or a display unit, the resin composition may be applied only to any one surface of the protective base material having the light shielding portion, preferably to any one surface of the surface provided with the light shielding portion and the touch surface of the touch panel or the display surface of the display unit, or may be applied to both surfaces in step 1.

In the case of the optical member of (vi) above obtained by bonding a protective substrate for protecting a display screen of a display unit or a touch panel to the display unit, the resin composition may be applied to only one of the surface of the protective substrate on which the light-shielding portion is provided, the surface of the touch panel opposite to the touch surface, and the display surface of the display unit in step 1, or may be applied to both surfaces.

The display unit including the optical base material having the light-shielding portion obtained by the manufacturing method of the present invention can be incorporated into electronic devices such as televisions, small-sized game machines, mobile phones, and personal computers.

[ examples ]

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

Preparation of ultraviolet-curable resin composition

The resin composition was prepared by heating and mixing 45 parts by weight of urethane acrylate (a reaction product obtained by reacting three components of polypropylene glycol (molecular weight 3000), isophorone diisocyanate, and 2-hydroxyethyl acrylate in a molar ratio of 1:1.3: 2), 25 parts by weight of ユニセーフ PKA-5017 (polyethylene glycol polypropylene glycol allyl butyl ether, manufactured by nippon), 10 parts by weight of ACMO (acryloylmorpholine, manufactured by yokogaku corporation), 20 parts by weight of LA (lauryl acrylate, manufactured by osaka organic chemical industry co., ltd.), and 0.5 part by weight of スピードキュア TPO (2,4, 6-trimethylbenzoyldiphenylphosphine oxide, manufactured by lammson corporation) (ultraviolet-curable resin composition a).

The obtained ultraviolet curable resin composition a of the present invention was used to perform the following evaluation.

Example 1

As shown in FIG. 1(a), the prepared ultraviolet-curable resin composition A was applied to the display surface of a liquid crystal display cell 1 having an area of 3.5 inches and the surface of a transparent glass substrate 2 having a light-shielding portion 4 (width 5mm) on which the light-shielding portion was provided so that the film thicknesses thereof were 125 μm, respectively. Then, the coating layer 5 obtained was irradiated from the atmosphere side with an integrated light amount of 2000mJ/cm with a high-pressure mercury lamp (80W/cm, ozone-free) through an ultraviolet shielding plate 6 in the exposure area at the time of bonding²The ultraviolet ray 9 of (2) cures the coating layer located in the light-shielding region at the time of bonding.

Next, as shown in fig. 1(b), the liquid crystal display unit 1 and the transparent substrate 2 having the light-shielding portion are bonded so that the coating layers 7 cured in the respective light-shielding regions face each other. Finally, as shown in FIG. 1C, the coating layer 7 was irradiated from the transparent glass substrate 2 side having a light-shielding portion with an integrated light amount of 2000mJ/cm using a high-pressure mercury lamp (80W/cm, ozone-free)²The uncured coating layer is cured by the ultraviolet ray 9, thereby producing the optical member (liquid crystal display unit having a transparent glass substrate having a light shielding portion) of the present invention.

Example 2

As shown in FIG. 2(a), the prepared ultraviolet-curable resin composition A was applied to a transparent glass substrate 2 having an area of 3.5 inches and a light-shielding portion 4 (width 5mm) so that the film thickness was 250. mu.m. Then, the coating layer 5 obtained was irradiated from the atmosphere side with an integrated light amount of 2000mJ/cm with a high-pressure mercury lamp (80W/cm, ozone-free) through an ultraviolet shielding plate 6 in the exposure area at the time of bonding²Ultraviolet ray of (2)And 9, curing the coating layer in the light shielding area during bonding.

Next, as shown in fig. 2(b), the liquid crystal display unit 1 and the transparent substrate 2 having a light shielding portion are bonded so that the coating layer 7 obtained by curing the light shielding region on the transparent substrate 2 having a light shielding portion faces the display surface of the liquid crystal display unit 1. Finally, as shown in FIG. 2(c), the coating layer 7 was irradiated from the transparent glass substrate 2 side having a light-shielding portion with an integrated light amount of 2000mJ/cm using a high-pressure mercury lamp (80W/cm, ozone-free)²The uncured coating layer is cured by the ultraviolet ray 9, thereby producing the optical member (liquid crystal display unit having a transparent glass substrate having a light shielding portion) of the present invention.

Comparative example 1

As shown in fig. 3(a), the prepared ultraviolet curable resin composition a was applied to the display surface of the liquid crystal display unit 1 and the surface provided with the light shielding portion on the transparent substrate 2 having the light shielding portion 4 (width 5mm) so that the film thicknesses thereof were 125 μm, respectively.

Next, as shown in fig. 3(b), the liquid crystal display unit 1 and the transparent substrate 2 having the light shielding portion 4 are bonded so that the coating layers 5 face each other. Finally, as shown in FIG. 3(c), the uncured coating layer was irradiated from the side of the transparent glass substrate 2 having the light-shielding portion with a cumulative light amount of 2000mJ/cm using an ultra-high pressure mercury lamp (TOSCURE752, manufactured by Toshiba Kasei Lighting Co., Ltd., Harrison)²And (3) ultraviolet rays 9, thereby curing the coating layer to produce a comparative optical member.

(measurement of degree of curing)

The transparent substrate was removed from the obtained optical member, and the resin cured layer located in the region shielded by the light shielding portion was rinsed off with isopropyl alcohol. Thereby, the uncured resin composition was removed. Then, the curing degree was measured by confirming the curing state of the resin cured layer located in the light-shielding region. The degree of curing was evaluated based on the following criteria.

Curing degree:

… (no trace of removal of the uncured resin composition was observed).

Δ … was semi-cured (although cured products remained, traces of removal of uncured resin composition could also be observed).

X … was completely uncured (completely no cured product remained).

	Example 1	Example 2	Comparative example 1
				Degree of curing	○	○	×

From the above results, it is understood that, in the optical member manufactured by the manufacturing method of the present invention, even if the ultraviolet rays are blocked by the light blocking portion of the protective substrate, the resin cured layer located in the light blocking region has a high degree of curing.

The ultraviolet curable resin composition a of the present invention obtained above was used to perform the following evaluation.

(curing Property)

Two pieces of a 1mm thick carrier were preparedThe obtained ultraviolet-curable resin composition A was coated on one of the glass slides so that the film thickness became 200. mu.m. Another glass slide was attached to the obtained coating layer. The coating layer sandwiched between two glass slides was irradiated with a cumulative light amount of 2000mJ/cm using a high-pressure mercury lamp (80W/cm, ozone-free) through glass²Ultraviolet rays of (1). The cured product was visually checked for its cured state, and as a result, it was completely cured.

(curing shrinkage ratio)

Two glass slides coated with a fluorine-containing release agent and having a thickness of 1mm were prepared, and the obtained ultraviolet-curable resin composition A was coated on the release agent-coated surface of one of the glass slides so that the film thickness was 200 μm. Then, the two glass slides were bonded so that the release agent-coated surfaces thereof faced each other. The coating layer sandwiched between two glass slides was irradiated with a cumulative light amount of 2000mJ/cm using a high-pressure mercury lamp (80W/cm, ozone-free) through glass²The ultraviolet ray of (2) to cure the coating layer. Then, the two glass slides were peeled off to prepare a cured product thin film for measuring film specific gravity.

The specific gravity (DS) of the cured product was measured by the method of JISK 7112B. Further, the liquid specific gravity (DL) of the ultraviolet curable resin composition at 25 ℃ was measured. From the measurement results of DS and DL, the curing shrinkage was calculated by the following formula and found to be less than 2.0%.

Curing shrinkage (%) = (DS-DL) ÷ DS × 100

(tackiness)

A glass slide having a thickness of 0.8mm and an acrylic resin plate having a thickness of 0.8mm were prepared, the obtained ultraviolet curable resin composition A was applied to one of the glass slides so as to have a film thickness of 200 μm, and the other was bonded to the glass slide so as to sandwich the obtained applied layer. The clamped coating layer was irradiated with a cumulative light amount of 2000mJ/cm using a high-pressure mercury lamp (80W/cm, ozone-free) through a glass slide²The coating layer was cured by ultraviolet rays of (2) to prepare a sample for evaluation of adhesiveness. The mixture was left at 85 ℃ and 85% RH for 250 hours. The evaluation sample is visually checked with a slide glass orWhether or not the acrylic resin plate peeled off from the cured resin was not peeled off.

(softness)

The obtained ultraviolet curable resin composition a was sufficiently cured, and the flexibility was evaluated by measuring the hardness of the resin composition by a Durometer (Durometer) E hardness meter (Durometer) according to jis k 7215. More specifically, the ultraviolet-curable resin composition a was injected into a cylindrical mold so that the film thickness was 1cm, and the resin composition was sufficiently cured by irradiation with ultraviolet light. The hardness of the resulting cured product was measured using a Durometer hardness tester (type E). As a result, the measured value was less than 10, and the flexibility was excellent.

(transparency)

Two glass slides having a thickness of 1mm coated with a fluorine-containing release agent were prepared, and the obtained ultraviolet-curable resin composition was coated on the release agent-coated surface of one of the glass slides so that the cured film thickness became 200 μm. Then, the two glass slides were bonded so that the release agent-coated surfaces thereof faced each other. The resin composition was irradiated with a cumulative light amount of 2000mJ/cm through a glass using a high-pressure mercury lamp (80W/cm, ozone-free)²The resin composition is cured by the ultraviolet ray of (1). Then, the two glass slides were peeled off to prepare a cured product for transparency measurement. The transmittance of the resulting cured product was measured by a spectrophotometer (U-3310, Hitachi high tech Co., Ltd.) for transmittance in the wavelength region of 400 to 800nm and 400 to 450 nm. As a result, the transmittance at 400 to 800nm is 90% or more and the transmittance at 400 to 450nm is also 90% or more.

Description of the reference symbols

1 a liquid crystal display cell,

2 a transparent substrate having a light shielding portion,

3 a transparent substrate,

4 a light shielding portion,

5 coating layer of ultraviolet curable resin composition,

6 ultraviolet shielding plate (UV mask),

7 a coating layer of the ultraviolet curable resin composition cured in the light-shielding region during bonding,

8 resin cured layer,

9 ultraviolet ray

Claims (21)

1. A method for producing an optical member comprising at least a pair of optical substrates, which is obtained by bonding a transparent optical substrate having a light-shielding portion on the surface thereof and another optical substrate bonded thereto, by using an ultraviolet-curable resin composition, through the steps comprising the following steps 1 to 3,

step 1: a step of applying an ultraviolet-curable resin composition to a bonding surface of at least one of a transparent optical substrate having a light-shielding portion on the surface and another optical substrate bonded thereto to form a coating layer, selectively irradiating the following light-shielding region of the obtained coating layer with ultraviolet rays to selectively cure the light-shielding region, and forming a coating layer in an uncured state in the other portion,

the light-shielding region is a portion of the coating layer where ultraviolet rays are shielded by the light-shielding portion and ultraviolet rays are not irradiated when the coating layer is irradiated with ultraviolet rays by the transparent optical substrate having the light-shielding portion on the transmission surface thereof, which is obtained by bonding the two optical substrates,

step 2: a step of bonding the two optical substrates by sandwiching the coating layer obtained in the step 1 between bonding surfaces of the two optical substrates,

and step 3: and (2) irradiating a laminate having at least one pair of optical substrates bonded in the steps 1 and 2 with ultraviolet rays through the transparent optical substrate having a light-shielding portion to cure an uncured coating layer interposed between the two optical substrates.

2. The method for manufacturing an optical member according to claim 1, wherein, after the step 3, there is further a step 4 of,

and 4, step 4: and applying pressure to the bonded optical substrate.

3. The method for manufacturing an optical member according to claim 1, wherein in the step 1, when the light-shielded region is cured, an uncured remaining portion of the coating layer other than the light-shielded region is masked with an ultraviolet shielding plate, and ultraviolet rays are irradiated.

4. The method for producing an optical member according to claim 1, wherein in the step 1, the ultraviolet irradiation amount is at least 200mJ/cm²。

5. The method for producing an optical member according to claim 1, wherein in step 1, the ultraviolet curable resin composition is applied to at least one of a surface of the transparent optical substrate having the light shielding portion on the surface, on which the light shielding portion is provided, and a display surface of the display unit, which is another optical substrate to be bonded thereto, and the surface of the transparent optical substrate having the light shielding portion on the surface, on the side having the light shielding portion, and the display surface of the display unit are bonded so as to face each other with the obtained coating layer interposed therebetween.

6. The method for producing an optical member according to claim 1, wherein the transparent optical substrate having a light-shielding portion on a surface thereof is at least one optical substrate selected from the group consisting of a transparent glass substrate having a light-shielding portion, a transparent resin substrate having a light-shielding portion, and a glass substrate having a light-shielding portion and a transparent electrode formed thereon, and the other optical substrate bonded thereto is at least one optical substrate selected from the group consisting of a liquid crystal display unit, a plasma display unit, and an organic EL display unit.

7. The method for producing an optical member according to claim 1, wherein the ultraviolet-curable resin composition is an ultraviolet-curable resin composition containing a (meth) acrylate (A) and a photopolymerization initiator (B).

8. The method for producing an optical member according to claim 7, wherein the (meth) acrylate (A) is at least one selected from the group consisting of urethane (meth) acrylate, (meth) acrylate having a polyisoprene skeleton, and (meth) acrylate monomers, and the (meth) acrylate monomers are used in the meaning of (meth) acrylates other than urethane (meth) acrylate and (meth) acrylate having a polyisoprene skeleton.

9. The method for producing an optical member according to claim 8, wherein both (i) a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (ii) a (meth) acrylate monomer are contained as the (meth) acrylate (A).

10. The method for manufacturing an optical member according to claim 8 or 9, wherein the (meth) acrylate (a) is a urethane (meth) acrylate or a (meth) acrylate monomer having a polypropyleneoxy structure.

11. The method for producing an optical member according to claim 10, wherein the urethane (meth) acrylate is a urethane (meth) acrylate obtained by reacting polypropylene glycol, polyisocyanate, and a hydroxyl group-containing (meth) acrylate.

12. The method for producing an optical member according to claim 8 or 9, wherein the urethane (meth) acrylate has a weight average molecular weight of 7000 to 25000, and the (meth) acrylate having a polyisoprene skeleton has a number average molecular weight of 15000 to 50000.

13. The method for producing an optical member according to claim 8 or 9, wherein the other components than the (meth) acrylate (A) and the photopolymerization initiator (B) are contained, the urethane (meth) acrylate and the (meth) acrylate monomer are contained as the (meth) acrylate (A) in an amount of 20 to 80 wt% based on the total amount of the ultraviolet-curable resin composition, and 5 to 70 wt% based on the total amount of the ultraviolet-curable resin composition, and the photopolymerization initiator (B) is contained in an amount of 0.2 to 5 wt% based on the total amount of the ultraviolet-curable resin composition, with the remainder being the other components.

14. The method for producing an optical member according to claim 7, wherein the ultraviolet-curable resin composition further contains a softening component.

15. Use of an ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B) in the method for producing an optical member according to any one of claims 1 to 5.

16. The use of the ultraviolet-curable resin composition according to claim 15, wherein the (meth) acrylate (a) is at least one selected from the group consisting of urethane (meth) acrylate, (meth) acrylate having a polyisoprene skeleton and (meth) acrylate monomers, and the (meth) acrylate monomers are used in the meaning of (meth) acrylate other than urethane (meth) acrylate and (meth) acrylate having a polyisoprene skeleton.

17. The use of the ultraviolet-curable resin composition according to claim 15, wherein both (i) a urethane (meth) acrylate or a (meth) acrylate having a polyisoprene skeleton and (ii) a (meth) acrylate monomer are contained as the (meth) acrylate (A).

18. The use of the ultraviolet-curable resin composition according to claim 16, wherein the urethane (meth) acrylate is a urethane (meth) acrylate obtained by reacting polypropylene glycol, polyisocyanate and a hydroxyl group-containing (meth) acrylate.

19. An ultraviolet-curable resin composition comprising a (meth) acrylate (A) and a photopolymerization initiator (B) for use in the method for producing an optical member according to claim 1.

20. The ultraviolet-curable resin composition according to claim 19, wherein the (meth) acrylate (a) is at least one selected from the group consisting of urethane (meth) acrylate, (meth) acrylate having a polyisoprene skeleton, and (meth) acrylate monomers, and the (meth) acrylate monomers are used in the meaning of (meth) acrylates other than urethane (meth) acrylate and (meth) acrylate having a polyisoprene skeleton.

21. The ultraviolet-curable resin composition according to claim 19, further comprising a softening component.