Manufacturing method of optical laminate and manufacturing apparatus of optical laminate

Abstract

To provide a manufacturing method for an optical laminate and a manufacturing apparatus for an optical laminate, by which the temperature unevenness in a width direction on a surface or a roll can be reduced and the problem of the quality of a bonding film can be reduced.SOLUTION: A manufacturing method for an optical laminate includes a bonding step of forming a bonding film from two different films through an adhesive of an energy line activation type, and an activating step of irradiating the bonding film with an energy line while bringing the bonding film into contact with the roll so as to activate the adhesive. A heat medium flow path for feeding a heat medium in the roll is provided. By heat medium circulating means, the temperature of the surface of the roll is adjusted. The heat medium flow path includes a main path extending in accordance with the entire region of an outer peripheral surface part of a roll main body part along a rotation shaft center, an introduction path for introducing the heat medium to the main path, a first discharge path connecting to the main path and discharging the heat medium flowing in the main path, and a second discharge path. The activating step includes an operation of feeding the heat medium into the heat medium flow path while the outer peripheral surface part rotates the roll main body part extending in a cylindrical shape.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing an optical laminate. [Background technology]

[0002] In the manufacture of optical laminates such as polarizing plates, the optical films constituting the optical laminate are laminated with an energy ray-activated adhesive, and then the resulting laminated film is subjected to an activation treatment while being transported. The activation treatment is performed by irradiating the laminated film passing over a roll with energy rays. The irradiation of the energy rays is usually performed while cooling the laminated film on a cooled roll so as to prevent quality problems of the laminated film such as deformation of the laminated film and uneven curing. Conventionally, as a method for cooling a roll, for example, as disclosed in JP 2019-3210 A (Patent Document 1), a method of flowing a heat medium inside the roll has been known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-3210 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a heat transfer medium is caused to flow through a roll as in the conventional method, there is a risk of temperature unevenness occurring in the width direction of the roll surface. The temperature unevenness in the width direction of the roll surface causes the reaction speed of the adhesive in the width direction of the laminated film to be non-uniform, which may cause problems with the quality of the laminated film.

[0005] Therefore, an object of the present disclosure is to provide a method and an apparatus for manufacturing an optical laminate that reduce temperature unevenness in the width direction of the surface of a roll and reduce problems with the quality of the laminated film. [Means for solving the problem]

[0006] In response to the above problem, the present inventors discovered that the temperature unevenness is caused by gas accompanying the circulation of the heat transfer medium, and thus completed the present invention. The method for producing the optical laminate of the present invention comprises the steps of: A method for producing an optical laminate having at least one layer made of an optical film, comprising: a bonding step of bonding two different films together via an energy ray activated adhesive to form a bonded film; an activation treatment step of irradiating the adhesive film on a roll with an energy ray while bringing the adhesive film into contact with the roll to activate the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll includes a roll body portion having a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, and a temperature of a surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, the heat medium flow path includes a main passage extending along the rotation axis so as to correspond to an entire area of ​​the outer circumferential surface portion of the roll body, an introduction passage extending on the rotation axis and communicating with the main passage to introduce the heat medium into the main passage, a first discharge passage extending on the rotation axis and communicating with the main passage to discharge the heat medium flowing into the main passage, and a second discharge passage having one end communicating with the main passage located downstream of the main passage and close to the outer circumferential surface portion and the other end communicating with the first discharge passage, The activation treatment step includes an operation of flowing a heat medium into the heat medium flow path while rotating the roll body.

[0007] According to the above aspect, the activation process includes an operation of flowing the heat medium in the heat medium passage while rotating the roll body, so that the heat medium can be flowed in the roll body while discharging the gas in the main passage from the second discharge passage. This reduces temperature unevenness in the width direction of the roll surface caused by the gas in the roll, makes the reaction speed of the adhesive in the width direction of the bonded film approximately uniform, and reduces problems with the quality of the bonded film.

[0008] The method for producing the optical laminate of the present invention further comprises the steps of: A method for producing an optical laminate having at least one layer made of an optical film, comprising: a bonding step of bonding two different films together via an energy ray activated adhesive to form a bonded film; an activation treatment step of irradiating the adhesive film on a roll with an energy ray while bringing the adhesive film into contact with the roll to activate the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll includes a roll body portion having a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, and a temperature of a surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, the heat medium flow path includes a main passage extending along the rotation axis so as to correspond to an entire area of ​​an outer circumferential surface portion of the roll body, and a discharge passage for discharging the heat medium flowing in the main passage, The activation treatment process includes an operation of flowing a heat medium into the heat medium flow path while rotating the roll body, and the volume of the heat medium flowing in the main passage is maintained in the range of 90% to 100% of the total volume of the main passage.

[0009] According to the above aspect, the activation process includes an operation of flowing the heat medium in the heat medium flow path while rotating the roll body, and the volume of the heat medium flowing in the main passage is maintained at 90% or more and 100% or less of the total volume of the main passage, so that the heat medium can be flowed in the roll body while the gas in the main passage is discharged from the discharge passage. This reduces temperature unevenness in the width direction of the roll surface caused by the gas in the roll, makes the reaction speed of the adhesive in the width direction of the laminated film approximately uniform, and reduces problems with the quality of the laminated film.

[0010] Preferably, in one embodiment of the method for producing an optical laminate, the activation treatment step is carried out in a state in which a temperature distribution in the width direction of the surface of the roll body is maintained at 3.5° C. or less.

[0011] According to the above embodiment, the activation treatment process is carried out in a state where the temperature distribution in the width direction of the surface of the roll body is maintained at 3.5°C or less, so that the temperature unevenness in the width direction of the roll surface can be further reduced, and problems with the quality of the laminated film can be further reduced.

[0012] In one embodiment of the method for producing the optical laminate, a step of irradiating the activated lamination film 33 with energy rays is included.

[0013] According to the embodiment, the method further includes a step of irradiating the activation-treated bonding film with energy rays, so that the activation treatment of the adhesive can be performed more reliably.

[0014] In addition, the manufacturing apparatus for an optical laminate according to one embodiment of the present disclosure includes: An apparatus for producing an optical laminate having at least one layer made of an optical film, comprising: a lamination device that laminates two different films together with an energy ray activated adhesive to form a laminated film; A roll that contacts the laminated film; an activation treatment device for irradiating the adhesive film on the roll with an energy ray to perform an activation treatment of the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll includes a roll body portion having a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, and a temperature of a surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, The heat medium flow path includes a main passage extending along the rotation axis to correspond to the entire outer peripheral surface portion of the roll body, an introduction passage extending on the rotation axis and communicating with the main passage to introduce the heat medium into the main passage, a first discharge passage extending on the rotation axis and communicating with the main passage to discharge the heat medium that has flowed into the main passage, and a second discharge passage having one end connected to the main passage located downstream of the main passage and close to the outer peripheral surface portion and the other end connected to the first discharge passage.

[0015] According to the above-mentioned aspect, the heat medium flow passage of the roll has the second discharge passage communicating with the main passage, so that the heat medium can be caused to flow into the roll body while the gas in the main passage is discharged from the second discharge passage. This reduces temperature unevenness in the width direction of the roll surface caused by the gas in the roll, makes the reaction speed of the adhesive in the width direction of the bonded film approximately uniform, and reduces problems with the quality of the bonded film.

[0016] Preferably, in one embodiment of the optical laminate manufacturing apparatus, when the activation treatment of the adhesive is performed by the activation treatment device, the apparatus further includes a control device that controls the temperature distribution in the width direction of the surface of the roll body portion to be maintained at 3.5°C or less.

[0017] According to the above embodiment, when the activation process of the adhesive is performed using the activation treatment device, the temperature distribution in the width direction of the surface of the roll body is controlled, thereby further reducing temperature unevenness in the width direction of the surface of the roll, and further reducing problems with the quality of the laminated film.

[0018] Preferably, in one embodiment of the apparatus for producing an optical laminate, The roll body has an outer tube and an inner tube, The space between the outer pipe and the inner pipe constitutes a part of the heat medium flow path.

[0019] According to the embodiment, the space between the outer tube and the inner tube constitutes a part of the heat transfer medium flow path, so that the heat transfer medium flows only in a part of the space inside the outer tube, and therefore the flow rate can be increased with a smaller amount of heat transfer medium compared to a single tube roll of the same diameter.

[0020] Preferably, in one embodiment of the apparatus for producing an optical laminate, two or more second discharge passages are provided.

[0021] According to the embodiment, since two or more second exhaust passages are provided, the gas can be efficiently exhausted.

[0022] Preferably, in one embodiment of the apparatus for producing an optical laminate, the second discharge passages are provided at equal intervals around the rotation axis.

[0023] According to the above embodiment, when the roll is rotating, each second discharge passage passes through the gas pool above the roll at short intervals, so that the time for discharging the gas accumulated above the main passage per rotation of the roll is increased, and the heat medium can be efficiently filled in the main passage. Effect of the Invention

[0024] According to the method and apparatus for producing an optical laminate according to one aspect of the present disclosure, temperature unevenness in the width direction of the surface of the roll can be reduced, thereby reducing problems with the quality of the laminated film. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of an apparatus for producing an optical laminate. [Diagram 2] FIG. 2 is a schematic cross-sectional view of one embodiment of a roll. [Diagram 3] FIG. 3 is a cross-sectional view taken along line II-II in FIG. [Figure 4]FIG. 3 is an enlarged view of part III in FIG. 2. [Figure 5A] FIG. 4 is a schematic cross-sectional view showing another embodiment of the roll. [Figure 5B] 5B is a cross-sectional view taken along line AA in FIG. 5A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, a method and an apparatus for producing an optical laminate according to one aspect of the present disclosure will be described in detail with reference to the illustrated embodiments. Note that the drawings include some schematic views and may not reflect actual dimensions or proportions.

[0027] (Embodiment) (Production equipment for optical laminates) Fig. 1 is a schematic diagram showing one embodiment of an apparatus for producing an optical laminate. As shown in Fig. 1, the apparatus for producing an optical laminate 15 includes a laminating device 16 for laminating a first film 31 and a second film 32, which are different from each other, to form a laminated film 33, a roll 2 in contact with the laminated film 33, an activation treatment device 13 for irradiating the laminated film 33 with energy rays to form an optical laminate 34, and a control device 17 for controlling the roll 2.

[0028] In this embodiment, the first film 31 is an optical film such as a polarizing film, the second film 32 is a transparent film, and the optical laminate 34 is a polarizing plate. These films are transported in the direction indicated by the arrow in FIG.

[0029] The optical film is a resin film exhibiting optical properties, such as a polarizing film, a retardation film, etc. The polarizing film is formed, for example, by dyeing a uniaxially stretched polyvinyl alcohol film with iodine or a dichroic dye, and then treating it with boric acid. Examples of the transparent film include thermoplastic resins such as amorphous polyolefin-based resin films, polyester-based resin films, acrylic-based resin films, polycarbonate-based resin films, polysulfone-based resin films, and alicyclic polyimide-based resin films. Examples of the transparent film include resin films with low moisture permeability. Examples of the transparent film further include cellulose acetate-based resin films such as triacetyl cellulose films and diacetyl cellulose films.

[0030] The optical film may be a single layer or a laminate. The type of the optical film is not particularly limited as long as it exhibits optical properties. The obtained optical laminate may have a film that does not exhibit optical properties, and may be, for example, an optical film such as a retardation film, a protective film, or the above-mentioned polarizing film, or an optical laminate in which these films and thermoplastic resins are laminated, as long as it exhibits optical properties. In other words, the optical laminate may have at least one layer made of an optical film.

[0031] The laminating device 16 has an adhesive applicator 11 that applies an adhesive to one side of the first film 31, and a first laminating roll 21 and a second laminating roll 22 that overlap the first film 31 and the second film 32 and laminate them via the adhesive. The adhesive is an energy ray activated adhesive.

[0032] For example, an epoxy resin that does not contain an aromatic ring in the molecule is used as the adhesive from the viewpoints of weather resistance, refractive index, cationic polymerization, etc. For example, a hydrogenated epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, etc. is used as the epoxy resin. A polymerization initiator, for example, a photo-cationic polymerization initiator for polymerization by irradiation with active energy rays, a thermal cationic polymerization initiator for polymerization by heating, and other additives (sensitizer, etc.) are added to the epoxy resin.

[0033] The roll 2 is rotated so that the center line of the roll 2 coincides with the rotation axis, and the laminated film 33 is conveyed while being in contact with the surface of the roll 2. The roll 2 comes into contact with the laminated film 33. That is, when the laminated film 33 is irradiated with energy rays from the activation treatment device 13, the roll 2 comes into contact with the laminated film 33, thereby making it difficult for heat to be applied to the laminated film 33. The roll 2 has a heat medium flow path therein through which a heat medium flows, and the laminated film 33 is cooled by the heat medium flowing through the heat medium flow path. The heat medium is, for example, a refrigerant such as water.

[0034] The roll 2 has a roll body portion whose outer circumferential surface portion extends cylindrically. The temperature of the surface of the roll 2 is adjusted by a heat medium circulating means that circulates the heat medium in a heat medium flow path. The heat medium circulating means is composed of a heat medium circulating unit including, for example, a circulation pump, and is controlled by a control device 17.

[0035] The heat medium flow path includes a main passage extending along the rotation axis to correspond to the entire outer peripheral surface of the roll body, an introduction passage extending on the rotation axis and communicating with the main passage for introducing the heat medium into the main passage, a first discharge passage extending on the rotation axis and communicating with the main passage for discharging the heat medium that has flowed into the main passage, and a second discharge passage having one end connected to the main passage located downstream of the main passage and close to the outer peripheral surface and the other end connected to the first discharge passage.

[0036] The heat medium flow path of the roll 2 has a second discharge passage communicating with the main passage, so that the heat medium can be caused to flow in the roll body while the gas in the main passage is discharged from the second discharge passage. The gas is, for example, air. The second discharge passage may discharge not only the gas but also the heat medium. Therefore, it is possible to reduce temperature unevenness in the width direction of the surface of the roll 2 caused by the gas in the roll 2, to make the reaction speed of the adhesive in the width direction of the bonded film 33 approximately uniform, and to reduce problems with the quality of the bonded film 33.

[0037] In addition, since the second discharge passage is connected to the main passage located close to the outer peripheral surface portion, when the rotation axis of the roll 2 is positioned horizontally for use, gas that has accumulated on the outer peripheral surface side of the main passage can be effectively discharged from the second discharge passage. Furthermore, since the second discharge passage communicates with the downstream side of the main passage, the gas can be efficiently discharged in accordance with the flow of the heat medium.

[0038] The roll body may be formed, for example, from a single outer tube, in which case the space inside the outer tube constitutes a part of the heat transfer medium flow path (main passage). The roll body may be formed, for example, from a double tube made up of an outer tube and an inner tube, in which case the space between the outer tube and the inner tube constitutes a part of the heat transfer medium flow path (main passage). The space between the outer tube and the inner tube is formed in an annular shape when viewed from the direction of the rotation axis of the roll 2.

[0039] The activation treatment device 13 is disposed facing the roll 2. The activation treatment device 13 irradiates the bonding film 33 on the roll 2 with energy rays to perform an activation treatment of the adhesive. That is, the activation treatment device 13 polymerizes and hardens the adhesive by irradiating it with energy rays. In this way, the optical laminate 34 formed by the activation treatment of the activation treatment device 13 is taken up by the take-up roll 20. Note that the energy rays are usually irradiated not only onto the roll 2 but also onto the periphery of the roll 2. The activation treatment device 13 has an emission distribution at wavelengths of 400 nm or less, and uses a low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, extra high pressure mercury lamp, chemical lamp, black light lamp, microwave excited mercury lamp, metal halide lamp, etc.

[0040] The control device 17 preferably controls the temperature distribution (maximum temperature difference) in the width direction of the surface of the roll body to be maintained at 3.5° C. or less, more preferably 2° C. or less, when the activation treatment device 13 performs the activation treatment of the adhesive. In other words, the control device 17 preferably sets the difference between the maximum temperature in the width direction of the surface of the roll body and the minimum temperature in the width direction of the surface of the roll body to be 3.5° C. or less. This can further reduce the temperature unevenness in the width direction of the surface of the roll 2, and further reduce problems with the quality of the laminated film 33. Specifically, the control device 17 is composed of a central processing unit. The control device 17, for example, controls the heat medium circulating means to adjust the flow rate of the heat medium in the roll 2, the flow rate of the heat medium in the roll 2, or the amount of the heat medium in the roll 2, thereby maintaining the temperature distribution in the width direction of the surface of the roll 2 at 3.5° C. or less.

[0041] Preferably, the roll body has an outer tube and an inner tube, and the space between the outer tube and the inner tube constitutes a part of the heat transfer medium flow path. With this, the heat transfer medium flows only in a part of the space inside the outer tube, so that the flow rate can be increased with a smaller amount of heat transfer medium compared to the single-tube roll 2 having the same diameter.

[0042] Preferably, two or more second discharge passages are provided. This increases the number of second discharge passages, allowing the gas to be discharged efficiently. Preferably, the second discharge passages are provided at equal intervals around the rotation axis. This allows each second discharge passage to pass through the gas pool above the roll at short intervals during the rotation of the roll 2, increasing the time for discharging the gas pooled above the main passage per rotation of the roll 2, allowing the heat medium to be efficiently filled in the main passage.

[0043] The manufacturing apparatus of the present disclosure is not limited to the above-mentioned embodiment, and can be modified in design without departing from the gist of the present disclosure. The manufacturing apparatus may have two or more activation treatment devices and rolls. In the manufacturing apparatus, the activation treatment devices may be provided so as to face one roll.

[0044] (Method of manufacturing optical laminate) Next, one embodiment of a method for producing an optical laminate will be described with reference to FIG. First, the first film 31 and the second film 32 are laminated together via an energy ray-activated adhesive to form a laminated film 33. This is called a lamination process. Thereafter, while the laminated film 33 is in contact with the roll 2, the laminated film 33 is irradiated with energy rays on the roll 2 to perform an activation process of the adhesive. This is called an activation process.

[0045] Here, a heat medium flow path through which a heat medium flows is provided inside the roll 2. The roll 2 includes a roll body portion whose center line coincides with the rotation axis and whose outer circumferential surface portion extends cylindrically. The temperature of the surface of the roll 2 is adjusted by a heat medium circulating means that circulates the heat medium in the heat medium flow path.

[0046] The heat medium flow path includes a main passage extending along the rotation axis to correspond to the entire outer peripheral surface of the roll body, an introduction passage extending on the rotation axis and communicating with the main passage for introducing the heat medium into the main passage, a first discharge passage extending on the rotation axis and communicating with the main passage for discharging the heat medium that has flowed into the main passage, and a second discharge passage having one end connected to the main passage located downstream of the main passage and close to the outer peripheral surface and the other end connected to the first discharge passage. The activation treatment step includes an operation of flowing a heat medium into the heat medium flow path while rotating the roll body.

[0047] According to this, since the activation process includes an operation of flowing the heat medium in the heat medium passage while rotating the roll body, the heat medium can be flowed in the roll body while discharging the gas in the main passage from the second discharge passage. Therefore, it is possible to further reduce the temperature unevenness in the width direction of the surface of the roll 2 caused by the gas in the roll 2, to make the reaction speed of the adhesive in the width direction of the bonded film 33 approximately uniform, and to reduce problems with the quality of the bonded film 33.

[0048] Preferably, in the activation process, the volume of the heat medium flowing through the main passage is maintained at 90% to 100%, more preferably 95% to 100%, of the total volume of the main passage. This can further reduce the temperature unevenness in the width direction of the surface of the roll 2, and further reduce problems with the quality of the laminated film 33.

[0049] Here, the amount of gas discharged from the main passage can be adjusted by appropriately adjusting the flow rate of the heat medium flowing in the heat medium flow passage, the rotation speed of the roll body, the cross-sectional area of ​​each discharge passage, etc. In other words, the volume of the heat medium flowing in the main passage can be adjusted by discharging the gas in the main passage. The volume of the heat medium flowing in the main passage can be easily adjusted with the roll in the manufacturing apparatus of the present disclosure.

[0050] Preferably, the activation process is performed in a state where the temperature distribution in the width direction of the surface of the roll body is maintained at 3.5° C. or less (more preferably, 2° C. or less). This can further reduce the temperature unevenness in the width direction of the surface of the roll 2, and further reduce problems with the quality of the laminated film 33.

[0051] In the above activation treatment step, when the energy ray is irradiated multiple times onto the laminated film 33, the energy ray irradiation is usually performed using a manufacturing device equipped with two or more activation treatment devices. The energy ray irradiation may be performed while passing the laminated film through one roll facing two or more activation treatment devices, or may be performed while passing the laminated film through multiple rolls using a device having two or more rolls facing one or more activation treatment devices. In this embodiment, the method further includes a step of irradiating energy rays onto the activated bonding film 33. This makes it possible to more reliably activate the adhesive. In this embodiment, the step of irradiating the activated laminated film 33 with energy rays is different from the energy ray irradiation in the activation treatment step in that it is performed on a roll having a different configuration from the roll in the activation treatment step.

[0052] The manufacturing method of the present disclosure is not limited to the above-described embodiment, and the design can be modified without departing from the scope of the present disclosure. For example, the manufacturing method of the present disclosure is not limited to being realized by the manufacturing apparatus 15 of FIG. 1, and may be realized by other different apparatuses.

[0053] In another embodiment of the method for producing an optical laminate, the method includes a lamination step and an activation step, and a heat medium flow path for flowing a heat medium is provided inside the roll, the roll includes a roll body part whose center line coincides with the rotation axis and whose outer circumferential surface part extends cylindrically, and the temperature of the surface of the roll is adjusted by a heat medium circulating means for circulating the heat medium in the heat medium flow path. The heat medium flow path includes a main passage extending along the rotation axis so as to correspond to the entire area of ​​the outer circumferential surface part of the roll body part, and a discharge passage for discharging the heat medium flowing in the main passage. In other words, the discharge passage is not limited to the first discharge passage and the second discharge passage, and for example, the second discharge passage may not be present. The activation step includes an operation of flowing the heat medium in the heat medium flow path while rotating the roll body part. In the activation step, the volume of the heat medium flowing in the main passage is maintained at 90% to 100%, preferably 95% to 100%, of the total volume of the main passage.

[0054] According to this, the heat medium can be caused to flow in the roll body while the gas in the main passage is discharged from the discharge passage, which reduces temperature unevenness in the width direction of the roll surface caused by the gas in the roll, makes the reaction speed of the adhesive in the width direction of the bonded film approximately uniform, and reduces problems with the quality of the bonded film.

[0055] (Roll structure) Fig. 2 is a schematic cross-sectional view of an example of an apparatus equipped with a roll applicable to the manufacturing method of the present disclosure (hereinafter, this roll may be referred to as a "roll device 1"). As shown in Fig. 2, the roll device 1 is in contact with the continuously transported bonded film W1 (bonded film 33 in Fig. 1) to adjust the temperature of the bonded film W1. The roll device 1 is included in the manufacturing apparatus 15 of the optical laminate.

[0056] The roll device 1 has a heat medium flow path 10 through which the heat medium H1 flows and includes the above-mentioned roll 2 rotatable about a rotation axis C1, and a heat medium circulation unit 3 (the heat medium circulation means) that circulates the heat medium H1 in the heat medium flow path 10.

[0057] The roll 2 is made of a metal material and includes a roll body 4 having a roll center line coinciding with the rotation axis C1 and an outer circumferential surface portion 4a extending cylindrically, a pair of shaft portions 5 formed integrally with each end surface portion 4b of the roll body 4 and having an axial center line coinciding with the rotation axis C1, and a pair of rotary joints 6 connecting each shaft portion 5 to the heat medium circulation unit 3, and each shaft portion 5 is rotatably supported by a support frame 7 via a bearing B1.

[0058] The heat medium flow path 10 includes a main passage 10a formed inside the roll body 4, an introduction passage 10b that extends linearly on the rotation axis C1 of one of the shaft portions 5 and communicates with the main passage 10a, and a first discharge passage 10c that extends linearly on the rotation axis C1 of the other shaft portion 5 and communicates with the main passage 10a.

[0059] The main passage 10a has a circular cross section and extends along the rotation axis C1 so as to correspond to the entire outer circumferential surface portion 4a. The introduction passage 10b has a circular cross section and is set to have a smaller cross section than the main passage 10a, and introduces the heat medium H1 discharged from the heat medium circulation unit 3 into the main passage 10a. The first discharge passage 10c has a circular cross section and is set to have a cross-sectional area narrower than that of the main passage 10a, and discharges the heat medium H1 in the main passage 10a to the heat medium circulation unit 3. In other words, the cross-sectional area of ​​the first discharge passage 10c is narrower than the cross-sectional area of ​​a portion of the main passage 10a that extends along the rotation axis C1 to correspond to the entire outer circumferential surface portion 4a. The heat medium circulation unit 3 circulates the heat medium H1 from one end side to the other end side of the roll 2, and the heat medium H1 passes through the inside of the roll 2 through the introduction passage 10b, the main passage 10a, and the first discharge passage 10c in this order.

[0060] Second discharge passages 10d extending in an L-shape in front view are formed inside the other end surface portion 4b of the roll body 4. As shown in Fig. 2 to Fig. 4, one end of the second discharge passages 10d is connected to the main passage 10a at a position downstream of the main passage 10a in the roll body 4 and close to the outer circumferential surface portion 4a, and the other end is connected to the upstream side of the first discharge passage 10c, and 12 second discharge passages 10d are formed at equal intervals around the rotation axis C1.

[0061] Next, the flow of the heat medium H1 inside the roll 2 when the roll device 1 is operated will be described in detail. First, the heat medium circulation unit 3 in the roll device 1 is operated. Then, the heat medium H1 flows through the introduction passage 10b, the main passage 10a, and the first discharge passage 10c in the roll 2 in this order.

[0062] Next, the roll 2 is rotated to one side (arrow R1 in FIG. 3) around the rotation axis C1 and contacted with the continuously conveyed laminated film W1. At this time, the heat medium H1 flows through the introduction passage 10b, the main passage 10a, and the first discharge passage 10c in this order inside the roll 2. Then, the heat medium H1 can be made to flow inside the roll body 4 while the gas in the main passage 10a is discharged from the second discharge passage 10d. It is preferable that the heat medium H1 circulates so as to be in constant contact with the entire back surface of the outer peripheral surface portion 4a in the roll body 4. When the heat medium H1 circulates so as to be in constant contact with the entire back surface of the outer peripheral surface portion 4a, the outer peripheral surface portion 4a in the roll body 4 is cooled without variation, so that it is possible to prevent the occurrence of variation in temperature distribution in the laminated film W1 in contact with the roll 2.

[0063] In addition, since gas does not accumulate on the upper part of the roll body 4, the time required to cool the outer circumferential surface part 4a to a desired temperature is shortened, and the bonded film W1 can be cooled efficiently.

[0064] In addition, since the second discharge passages 10d are formed at two or more places at equal intervals around the rotation axis C1, each second discharge passage 10d passes through the gas pool above the roll 2 at short intervals during the rotation of the roll 2. Therefore, the time for discharging the gas pooled above the main passage 10a per rotation of the roll 2 is increased, and the main passage 10a can be efficiently filled with the heat medium H1 without any gaps.

[0065] In addition, since each second discharge passage 10d is formed inside the end surface portion 4b of the roll body 4, the outer shape of the roll 2 is smaller than when a structure having the second discharge passages 10d is attached to the outside of the roll body 4. Therefore, the entire roll 2 can be made compact, and the space around the roll 2 can be used effectively.

[0066] (Other structures of the roll) Fig. 5A is a schematic cross-sectional view showing another embodiment of a roll applicable to the manufacturing method and manufacturing apparatus of the present disclosure. Fig. 5B is a cross-sectional view taken along the line AA in Fig. 5A. This roll 50 is a double-tube roll, unlike the roll 2 in Fig. 2 which is a single tube. Only the parts different from the roll 2 will be described below.

[0067] 5A and 5B, roll 50 has an outer tube 51, an inner tube 52, a first shaft portion 53, and a second shaft portion 54. Inner tube 52 is disposed inside outer tube 51, and outer tube 51 and inner tube 52 constitute a roll main body. First shaft portion 53 is provided at one end of the roll main body, and second shaft portion 54 is provided at the other end of the roll main body.

[0068] The roll 50 has a heat medium flow path 55 through which the heat medium flows. The heat medium flow path 55 has a main path provided in the roll main body (the outer tube 51 and the inner tube 52), an introduction path 55d provided in the first shaft portion 53, and a first discharge path 55e provided in the second shaft portion 54.

[0069] The main passage is composed of a first passage 55a having an annular cross section located between the outer tube 51 and the inner tube 52 when viewed from the direction of the rotation axis C1 of the roll 50, a plurality of second passages 55b extending radially from the rotation axis C1 and communicating with one end side of the first passage 55a, and a plurality of third passages 55c extending radially from the rotation axis C1 and communicating with the other end side of the first passage 55a.

[0070] The first passage 55a extends along the rotation axis C1 so as to cover the entire outer peripheral surface portion 51a of the roll body. The second passages 55b and the third passages 55c are formed at equal intervals around the rotation axis C1. Each of the second passages 55b connects the introduction passage 55d to the first passage 55a, and each of the third passages 55c connects the first passage 55a to the first discharge passage 55e. The first discharge passage 55e is set to have a narrower cross section than the first passage 55a, that is, the cross-sectional area of ​​the first discharge passage 55e is narrower than the cross-sectional area of ​​the portion of the main passage that extends along the rotation axis C1 to cover the entire outer circumferential surface portion 51a. Then, as indicated by the dotted arrow in FIG. 5A, the heat medium passes from the introduction passage 55d through the second passage 55b, the first passage 55a and the third passage 55c in this order, and is discharged from the first discharge passage 55e.

[0071] A plurality of second discharge passages 55f extending substantially radially are disposed around the second shaft portion 54 at equal intervals around the rotation axis C1 when viewed from the direction of the rotation axis C1. The second discharge passages 55f include piping. The piping is formed of, for example, a piping tube made of a rubber material, but may also be formed of a metal pipe or a resin pipe. One end of the second discharge passage 55f communicates with the main passage (first passage 55a) downstream of the main passage and close to the outer circumferential surface portion 51a, and the other end of the second discharge passage 55f communicates with the first discharge passage 55e. The movement of the gas accumulating at the top of the main passage (first passage 55a) being discharged is the same as that of roll 2 in FIG. 2, except that the discharge path changes from second discharge passage 10d to second discharge passage 55f, and therefore a detailed explanation is omitted.

[0072] As a result, since the second discharge passage 55f is arranged outside the roll main body and the second shaft portion 54, the processing costs are lower than in a structure in which the second discharge passage 55f is formed inside the end portion of the roll main body, making it possible to produce a cost-effective roll 50.

[0073] (Example) Next, an embodiment will be described.

[0074] (First film) A 20 μm thick PVA film (average degree of polymerization approximately 2400, saponification degree 99.9 mol % or more) was uniaxially stretched approximately 6 times by dry stretching, and then immersed in pure water at 40° C. for 40 seconds while maintaining the tension.

[0075] Next, this film was dyed by immersing it in a dyeing aqueous solution having a mass ratio of iodine / potassium iodide / water of 0.044 / 5.7 / 100 at 28° C. for 30 seconds, and then crosslinked by immersing the dyed film in a boric acid aqueous solution having a mass ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70° C. for 120 seconds.

[0076] The crosslinked film was then washed with pure water at 8° C. for 15 seconds, and then dried at 60° C. for 50 seconds and then at 75° C. for 20 seconds while maintaining a tension of 300 N / m. In this way, a polarized film with a thickness of 7 μm was obtained in which iodine was adsorbed and oriented in the PVA film.

[0077] A cycloolefin resin film (COP, Zeon Corporation ZF-14, no UV absorption characteristics, thickness 13 μm) was prepared as a protective film. A water-based adhesive was injected between the obtained polarizing film and the cycloolefin resin film, and they were bonded together using a nip roll. The obtained laminate was dried at 60° C. for 2 minutes while maintaining the tension at 430 N / m, to obtain a first film including a polarizer layer and a protective layer disposed on one side of the polarizer layer. The thickness of the first film was 20 μm.

[0078] The water-based adhesive was prepared by adding 3 parts by mass of carboxyl group-modified polyvinyl alcohol (Kuraray Co., Ltd.; Kuraray Poval (registered trademark) KL318) and 1.5 parts by mass of water-soluble polyamide epoxy resin (Taoka Chemical Co., Ltd.; Sumirez Resin (registered trademark) 650; aqueous solution with solid content of 30%) to 100 parts by mass of water.

[0079] (2nd film) A transparent film made of a polyethylene terephthalate film having a thickness of 38 μm was prepared. The composition for the alignment layer was applied to one side of the transparent film so as to have a film thickness of 3 μm, and the accumulated light amount was 20 mJ / cm 2 An alignment layer was formed by irradiating the film with ultraviolet light so as to form an alignment layer.

[0080] The above-mentioned composition for the alignment layer was prepared by mixing 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether in a ratio of 1:1:4:5, and adding LUCIRIN (registered trademark) TPO as a polymerization initiator in a ratio of 4% based on the total mass of the obtained mixture.

[0081] A liquid crystal composition containing a polymerizable nematic liquid crystal compound (RMM28B, manufactured by Merck) was applied onto the formed alignment layer by die coating.

[0082] The liquid crystal composition was prepared using a mixed heat medium of methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) with a boiling point of 155° C. in a mass ratio (MEK:MIBK:CHN) of 35:30:35. The liquid crystal composition was prepared so that the solid content was 1 to 1.5 g per 100 g of liquid crystal composition, and was applied onto the alignment layer so that the coating amount before drying was 4 to 5 g.

[0083] After the liquid crystal composition was applied onto the alignment layer, the resulting coating layer was dried at a drying temperature of 75°C for 120 seconds. The liquid crystal compound was then polymerized and hardened by ultraviolet (UV) irradiation. Thus, a second film was obtained that was composed of a retardation layer, an alignment layer, and a transparent film. This retardation layer satisfied the relationship nz>nx=ny and was a positive C layer. The total thickness of the retardation layer and the alignment layer was 4 μm.

[0084] (Method of manufacturing energy ray activated adhesive) To prepare the adhesive, compounds were mixed in the ratios shown in Table 1 below. In Table 1, the ratios of the compounds are expressed in parts by mass.

[0085] [Table 1]

[0086] Details of the compounds in Table 1 are as follows: Compound 1: [ka] 3',4'-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate ("CEL2021P" manufactured by Daicel Chemical Industries, Ltd., alicyclic diepoxy)

[0087] Compound 2: [ka] Neopentyl glycol diglycidyl ether (NPGDGE) ("EX-211" manufactured by Nagase ChemteX Corporation, diepoxy)

[0088] Compound 3: [ka] 2-Ethylhexyl glycidyl ether (EHGE) (Tokyo Chemical Industry Co., Ltd., monoepoxy)

[0089] Initiator: Cationic initiator SP-500 (solid content 2.25 parts) manufactured by ADEKA Corporation Sensitizer: Sensitizer DEN manufactured by Kawasaki Kasei Chemical Industries, Ltd. Leveling agent: ADEKA Corporation's leveling agent KRM-430

[0090] (Method of manufacturing optical laminate) Using the manufacturing apparatus shown in FIG. 1, an optical laminate is produced in the following procedure. However, the roll used in the manufacturing apparatus is roll 50 as shown in FIG. 5A. Specifically, the roll has a second discharge passage connected to the main passage. The diameter of the pipe of the second discharge passage is 10 mm. The outermost diameter of the roll is 150 mm, and the length of the roll is 300 mm. The outer diameter of the first passage of the main passage (the inner diameter of the outer tube) is 128 mm, and the inner diameter of the first passage of the main passage (the outer diameter of the inner tube) is 100 mm. The cross-sectional area of ​​the first passage of the main passage is 0.0050 m 2 It is.

[0091] Then, while the first film and the second film are continuously transported, the surfaces of the first film and the second film are subjected to a corona treatment. While the first film and the second film are still being transported, an energy ray activated adhesive is applied to the corona-treated surface of the first film using a coater (bar coater), and then the first film and the second film are superimposed and passed between a pair of laminating rolls to obtain a laminated film having a layer structure of the first film / coating layer / second film.

[0092] The laminated film obtained was transported at a speed of 10 m / min, and the integrated light dose on the laminated film was 250 mJ / cm 2 The adhesive is cured by irradiating it with ultraviolet light from an activation treatment device while it is in close contact with the roll body so that the ultraviolet light reaches a temperature of 1000 nm (UVB) and the adhesive is cured to obtain an optical laminate. The activation treatment device uses a high-pressure mercury lamp manufactured by iGraphics. [Explanation of symbols]

[0093] 1 Roller Unit 2 rolls 3 Heat medium circulation unit (heat medium circulation means) 4 Roll body 4a Outer surface part 4b End section 5 Shaft section 10 Heat transfer medium flow path 10a Main passage 10b Introduction passage 10c 1st discharge passage 10d 2nd discharge passage 15. Optical laminate manufacturing equipment 16 Laminating device 17 Control device 11 Adhesive coating device 13 Activation treatment equipment 20 Winding roll 21 First laminating roll 22 Second laminating roll 31 First film (polarizing film) 32 2nd film (transparent film) 33 Laminating film 34 Optical laminate (polarizing plate) 50 rolls 51 Outer tube (roll body) 51a Outer peripheral surface part 52 Inner tube (roll body) 53 First shaft 54 Second shaft 55 Heat transfer medium flow path 55a 1st aisle (main aisle) 55b 2nd aisle (main aisle) 55c 3rd aisle (main aisle) 55d Introduction Passage 55e 1st discharge passage 55f 2nd discharge passage C1 Rotation axis center

Claims

1. A method for producing an optical laminate having at least one layer made of an optical film, comprising: a bonding step of bonding two different films together via an energy ray activated adhesive to form a bonded film; an activation treatment step of irradiating the adhesive film on a roll with an energy ray while bringing the adhesive film into contact with the roll to activate the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll has a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, the roll body portion being constituted by an outer tube and an inner tube, and a temperature of the surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, the heat medium flow path is a main passage extending along the rotation axis so as to correspond to the entire outer peripheral surface portion of the roll body, the main passage being composed of a first passage having an annular cross section located between the outer tube and the inner tube as viewed from the direction of the rotation axis of the roll, a plurality of second passages extending radially from the rotation axis and communicating with one end side of the first passage, and a plurality of third passages extending radially from the rotation axis and communicating with the other end side of the first passage; an introduction passage extending on the rotation axis and communicating with the main passage to introduce the heat medium into the main passage; a first discharge passage extending on the rotation axis and communicating with the main passage to discharge the heat medium flowing into the main passage; and a second discharge passage having one end communicating with a main passage located downstream of the main passage and close to the outer peripheral surface portion and the other end communicating with the first discharge passage, The activation treatment step includes an operation of flowing a heat medium into the heat medium flow path while rotating the roll body.

2. A method for producing an optical laminate having at least one layer made of an optical film, comprising: a bonding step of bonding two different films together via an energy ray activated adhesive to form a bonded film; an activation treatment step of irradiating the adhesive film on a roll with an energy ray while bringing the adhesive film into contact with the roll to activate the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll has a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, the roll body portion being constituted by an outer tube and an inner tube, and a temperature of the surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, the heat medium flow path is a main passage extending along the rotation axis so as to correspond to an entire area of ​​an outer circumferential surface portion of the roll body, the main passage being composed of a first passage having an annular cross section located between the outer tube and the inner tube as viewed from the direction of the rotation axis of the roll, a plurality of second passages extending radially from the rotation axis and communicating with one end side of the first passage, and a plurality of third passages extending radially from the rotation axis and communicating with the other end side of the first passage, and a discharge passage for discharging the heat medium flowing in the main passage, The activation treatment step includes an operation of flowing a heat medium into the heat medium flow path while rotating the roll body, and a volume of the heat medium flowing in the main passage is maintained at 90% or more and 100% or less of a total volume of the main passage.

3. The method for producing an optical laminate according to claim 1 or 2, wherein the activation treatment step is performed in a state where a temperature distribution in a width direction of the surface of the roll body is maintained at 3.5° C. or less.

4. The method for producing an optical laminate according to claim 1 , further comprising a step of irradiating the activated laminate with energy rays.

5. An apparatus for producing an optical laminate having at least one layer made of an optical film, comprising: a lamination device that laminates two different films together via an energy ray activated adhesive to form a laminated film; A roll that contacts the laminated film; an activation treatment device for irradiating the adhesive film on the roll with an energy ray to perform an activation treatment of the adhesive; Equipped with A heat medium flow path through which a heat medium flows is provided inside the roll, the roll has a roll center line coinciding with a rotation axis and an outer circumferential surface portion extending cylindrically, the roll body portion being constituted by an outer tube and an inner tube, and a temperature of the surface of the roll is adjusted by a heat medium circulating means that circulates the heat medium through the heat medium flow path, the heat medium flow path is a main passage extending along the rotation axis to correspond to the entire outer peripheral surface portion of the roll body, the main passage being composed of a first passage having an annular cross section located between the outer tube and the inner tube when viewed from the direction of the rotation axis of the roll, a plurality of second passages extending radially from the rotation axis and communicating with one end side of the first passage, and a plurality of third passages extending radially from the rotation axis and communicating with the other end side of the first passage, an introduction passage extending on the rotation axis and communicating with the main passage to introduce the heat medium into the main passage, a first discharge passage extending on the rotation axis and communicating with the main passage to discharge the heat medium that has flowed into the main passage, and a second discharge passage having one end communicating with a main passage located downstream of the main passage and close to the outer peripheral surface portion and the other end communicating with the first discharge passage.

6. The optical laminate manufacturing apparatus according to claim 5, further comprising a control device that controls the temperature distribution in the width direction of the surface of the roll body to be maintained at 3.5°C or less when the activation treatment of the adhesive is performed by the activation treatment device.

7. The apparatus for producing an optical laminate according to claim 5 or 6, wherein two or more second discharge passages are provided.

8. The apparatus for producing an optical laminate according to claim 7 , wherein the second discharge passages are provided at equal intervals around the rotation axis.

Images