WO2019188593A1

WO2019188593A1 - Method for manufacturing optical film

Info

Publication number: WO2019188593A1
Application number: PCT/JP2019/011490
Authority: WO
Inventors: 尚志山本; 諭史長野
Original assignee: 富士フイルム株式会社
Priority date: 2018-03-28
Filing date: 2019-03-19
Publication date: 2019-10-03
Also published as: KR20200128718A; KR102434167B1; JPWO2019188593A1; JP6977152B2

Abstract

This method for manufacturing an optical film comprises: a step for applying and drying an active energy ray curable resin composition on a surface reverse to a surface having a knurling portion with a height of 2-10 μm of a continuous film support having the knurling portion along each of both ends in a width direction, thereby forming a coating film; and a step for winding the continuous film support on which the coating film is formed around a temperature regulating roll with the surface having the knurling portion being brought into contact therewith, and irradiating the coating film on the temperature regulating roll with an active energy ray.

Description

Manufacturing method of optical film

This disclosure relates to a method for manufacturing an optical film.

In recent years, demand for optical films is increasing. Typical examples of the optical film include a retardation film, an antireflection film, and an antiglare film.

The optical film is manufactured by a continuous process in a roll-to-roll manner using a long film-like support (hereinafter referred to as “continuous film support”) for improving productivity.
As an example of a method for producing an optical film, a coating film forming step for forming a coating film by applying and drying an active energy ray-curable resin composition on the surface of a continuous film support, and an activity for the formed coating film And an active energy ray irradiating step of irradiating the energy ray to cure the coating film, and a method of forming a desired optical functional layer on the surface of the continuous film support.
And when manufacturing an optical film by a continuous process in a roll-to-roll system, the continuous film support comes into contact with various rolls, so that the width of the continuous film support can be prevented from shifting. It is preferable to use a continuous film support having a portion where minute protrusions called knurling portions are formed along both ends in the direction.

For example, Japanese Patent Application Laid-Open No. 2017-32756 discloses a first region formed by knurling on a base film and a layer having a fine concavo-convex structure formed between the first regions on the surface. And a second region provided with a transparent film. Moreover, as a manufacturing method of this transparent film, the active energy ray-curable resin is applied by applying the active energy ray-curable resin composition on the base film on which the first region is formed as the second region. A method is disclosed in which an active energy ray-curable resin composition is cured by pressing a transfer die against the composition and irradiating active energy rays, and then the transfer die is separated.

Further, for example, in JP-A-2010-139824, a hard coat layer coating composition is coated on a long knurled cellulose triacetate film, and after drying, the coating layer is coated with an ultraviolet lamp. A method of curing is disclosed.

When manufacturing an optical film, in the active energy ray irradiation step, unevenness may occur in the irradiation amount of the active energy rays irradiated to the coating film in the width direction of the continuous film support. When there is unevenness in the irradiation amount of the active energy rays in the width direction of the continuous film support, the coating amount of the active energy ray-curable resin composition is usually applied in the width direction of the continuous film support in the coating film forming step. Is adjusted according to the unevenness of the irradiation amount. And by this adjustment, in the optical film manufactured, the dispersion | variation in the optical characteristic in the width direction is suppressed.
However, in the active energy ray irradiation step, when the transport position is shifted in the width direction of the continuous film support, the adjustment position of the application amount of the active energy ray curable resin composition performed in the coating film forming step is It will shift | deviate and the subject that it is difficult to suppress the dispersion | variation in the optical characteristic in the width direction in the optical film manufactured will arise. The shift of the transport position in the width direction of the continuous film support is reduced by using, for example, a continuous film support having a knurling portion. In order to effectively suppress the shift of the transport position, for example, when a continuous film support having a knurling part with a height of about 20 μm is used, the continuous film support is not formed due to the presence of the knurling part in the active energy ray irradiation step. Only the width direction end may float greatly. In the active energy ray irradiation process, if only the end in the width direction of the continuous film support is largely floated, the irradiation amount of the active energy ray will be different between the central portion and the end in the width direction, and the optical that is also produced There arises a problem that variations in optical characteristics in the width direction occur in the film.

In both Japanese Patent Application Laid-Open No. 2017-32756 and Japanese Patent Application Laid-Open No. 2010-139824, due to the influence of the knurling part provided on the continuous film support, the irradiation amount of the active energy beam is based on the irradiation amount of the active energy beam. It has not been studied at all about the difference between the central portion and the end in the width direction of the material film. Therefore, the technique described in Japanese Patent Application Laid-Open No. 2017-32756 and Japanese Patent Application Laid-Open No. 2010-139824 has a problem that the optical characteristics in the width direction of the manufactured optical film vary as described above. It is considered a thing.

Therefore, the problem to be solved by one embodiment of the present invention has been made in view of the above circumstances, and a coating film is cured by irradiation with active energy rays using a continuous process in a roll-to-roll system. An object of the present invention is to provide an optical film manufacturing method including a process, wherein variation in optical characteristics in the width direction is reduced.

Means for solving the above problems include the following embodiments.
<1> An active energy ray-curable resin composition is applied to a surface opposite to a surface having a knurling portion of a continuous film support having a knurling portion having a height of 2 μm to 10 μm along both ends in the width direction and dried. Forming a coating film; and
Wrapping the continuous film support on which the coating film is formed by bringing the surface having the knurling part into contact with the temperature control roll, irradiating the coating film on the temperature control roll with active energy rays,
The manufacturing method of the optical film which has this.

<2> The method for producing an optical film according to <1>, wherein the tension applied in the longitudinal direction of the continuous film support on which the coating film is formed on the temperature control roll is 150 N / m to 500 N / m.
<3> The method for producing an optical film according to <1> or <2>, wherein the surface temperature of the temperature control roll is 60 ° C. to 160 ° C.

<4> The method for producing an optical film according to any one of <1> to <3>, wherein the ratio of the sum of the width of the knurling portion to the total width of the continuous film support is 0.5% to 5.0%. .
<5> The method for producing an optical film according to any one of <1> to <4>, wherein a distance from an end in the width direction of the continuous film support to the knurling portion is 0 mm to 15 mm.
<6> The method for producing an optical film according to any one of <1> to <5>, wherein the thickness of the portion where the knurling portion of the continuous film support is not formed is 20 μm to 100 μm.

According to one embodiment of the present invention, in an optical film manufacturing method including a step of curing a coating film by irradiation of active energy rays using a roll-to-roll continuous process, variation in optical characteristics in the width direction is achieved. A method for producing an optical film with reduced is provided.

It is the schematic which shows each process of the manufacturing method of the optical film of one Embodiment. It is a top view of the continuous film support body used for the manufacturing method of the optical film of one Embodiment. It is an expanded sectional view of the knurling part in the continuous film support body used for the manufacturing method of the optical film of one Embodiment. It is sectional drawing which shows the distance of the temperature control roll at the time of irradiating an active energy ray, and a continuous film support body.

Hereinafter, an embodiment of an optical film manufacturing method will be described. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

In the present disclosure, a numerical range indicated by using “to” means a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In a numerical range described in stages in the present disclosure, an upper limit value or a lower limit value described in a numerical range may be replaced with an upper limit value or a lower limit value in another numerical range. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
The elements in the drawings shown in the present disclosure are not necessarily to scale, and focus is placed on clearly illustrating the principles of the present disclosure, and some points are emphasized.
Moreover, in each drawing, the same code | symbol is attached | subjected to the component which has the same function, and the overlapping description is abbreviate | omitted.
In the present disclosure, the “width direction” refers to a direction orthogonal to the longitudinal direction of the long continuous film support and the optical film.
In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

≪Method for manufacturing optical film≫
When the present inventors examined the manufacturing method of the optical film including the process of hardening a coating film by irradiation of an active energy ray using the continuous process by a roll to roll system, in the following methods, It has been found that variations in optical characteristics in the width direction are reduced.
That is, the active energy ray-curable resin composition is applied to the surface opposite to the surface having the knurling portion of the continuous film support having the knurling portion having a height of 2 μm to 10 μm along both ends in the width direction and dried. A process of forming a film and a continuous film support on which a coating film has been formed are wound around a temperature control roll while bringing the surface having a knurling portion into contact, and the coating film on the temperature control roll is irradiated with active energy rays. And a process for producing an optical film.
In the manufacturing method of said optical film, the continuous film support body which has a knurling part of the specific height which is not too high and is not too low is used. And the knurling part is made to contact a temperature control roll, it winds, and an active energy ray is irradiated with respect to the coating film on a temperature control roll in the area | region. By adopting this method, first, in the active energy ray irradiation step, it is possible to suppress the shift of the transport position in the width direction of the continuous film support. And since it is a knurling part of the optimal height, suppressing the shift | offset | difference of a conveyance position, only the width direction terminal of a continuous film support body does not float largely in an active energy ray irradiation process. For this reason, it is possible to reduce the difference in the irradiation amount of the active energy rays due to the floating between the central portion and the end in the width direction. As a result of these, it is possible to produce an optical film having no variation in optical characteristics in the width direction.

According to the manufacturing method of the optical film of one Embodiment, a cured film is formed on a continuous film support body through a coating-film formation process and an active energy ray irradiation process.
The formed cured film becomes an optical functional layer (for example, an optically anisotropic layer, an antireflection layer, an antiglare layer, etc.) in the optical film.

Hereinafter, the details of the coating film forming step and the active energy ray irradiation step in the method of manufacturing an optical film of one embodiment will be described.

[Coating film forming process]
In the coating film forming step, the active energy ray-curable resin composition is applied to the surface opposite to the surface having the knurling portion of the continuous film support having the knurling portion having a height of 2 μm to 10 μm along both ends in the width direction. Dry to form a coating.

An example of the coating film forming step will be described with reference to FIG.
As shown in FIG. 1, when the continuous film support 10 wound is sent out, the active energy ray-curable resin composition is first applied to the surface opposite to the surface having the knurling portion by the coating means 1. Is then applied and then dried in a drying area by the drying means 2. Thus, a coating film obtained by applying and drying the active energy ray-curable resin composition is formed on the continuous film support.
A continuous film support makes a knurling part contact with a temperature control roll at the active energy ray irradiation process mentioned later. Therefore, in this coating-film formation process, the surface where an active energy ray hardening resin composition is apply | coated becomes a surface opposite to the surface which has a knurling part of a continuous film support body.

-Continuous film support-
A known polymer film can be used for the continuous film support used for the production of the optical film.
Examples of polymeric film materials used as continuous film supports include cellulose acylate (eg, cellulose triacetate (triacetylcellulose, refractive index 1.48), cellulose diacetate, cellulose acetate butyrate, cellulose acetate propionate. ), Polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, acrylic resins such as polyethersulfone and polymethylmethacrylate, polyurethane, polycarbonate, polysulfone, polyether, polymethylpentene, polyetherketone, poly ( (Meth) acrylonitrile, polymer having alicyclic structure (for example, norbornene resin (trade name “Arton (registered trademark)”, JSR Corporation) , Amorphous polyolefins (for example, trade name "ZEONEX (registered trademark)", Nippon Zeon Co., Ltd.)), and the like.
Among these, from the viewpoint of low optical anisotropy and the like, triacetyl cellulose, polyethylene terephthalate (PET), and a polymer having an alicyclic structure are preferable, and triacetyl cellulose is particularly preferable.

The thickness of the portion where the knurling portion of the continuous film support is not formed may be determined according to the production suitability, the use, etc., and for example, the range of 3 μm to 250 μm is preferable. The thickness of the continuous film support is more preferably 20 μm or more from the viewpoint of high applicability to winding on a temperature control roll.
In particular, when the thickness of the continuous film support is thin, there is a tendency that the shift of the transport position and the lifting of the end portion in the width direction of the continuous film support tend to occur. By adopting, a thin continuous film support in the range of 20 μm to 100 μm is preferably used.
In addition, from the viewpoint of material cost, the thickness of the continuous film support is preferably 80 μm or less.
From the above, the thickness of the continuous film support is preferably 20 μm to 80 μm, more preferably 40 μm to 80 μm.

A continuous film support has a knurling part along the both ends of the width direction as shown to FIG. 2A.
Here, the “knurling portion” means a portion (12 in FIG. 2A) where a minute protrusion as shown in FIG. 2B is provided in the continuous film support.

The height of the knurling part is 2 μm to 10 μm, preferably 2 μm to 7 μm, from the viewpoint of preventing deviation of the transport position of the continuous film support and reducing the floating at the end of the continuous film support in the width direction. More preferably, it is 2 to 5 μm.
The height of the knurling part is the knurling part of the continuous film support, two locations of 5000 mm from the longitudinal tip of the continuous film support (that is, one each at both ends in the width direction), and It refers to the average value of the maximum heights of a total of four places at two places of 5000 mm from the end in the longitudinal direction of the continuous film support (that is, one place at each end in the width direction).
A specific measurement method is as follows.
First, at a position of 5000 mm from the longitudinal tip of the continuous film support, the thickness of the continuous film support is continuously measured from the inner side to the outer side by 100 mm from both ends in the width direction of the continuous film support. By this measurement, the thickness of the continuous film support can be measured from a location where the knurling portion is not formed to a region where the knurling portion is formed and the thickness is increased. And the average value of the thickness of the part where the knurling part is not formed is subtracted from the largest value measured in the region where the knurling part is formed and the thickness is large, that is, the thickness of the thickest part. The value is the maximum height. This is the maximum height of the knurling part of the continuous film support at two locations of 5000 mm from the longitudinal tip of the continuous film support (that is, one each at both ends in the width direction).
Subsequently, even at a position of 5000 mm from the end in the longitudinal direction of the continuous film support, the same measurement as described above is performed to determine the maximum height. This is the maximum height of the knurling part of the continuous film support at two locations of 5000 mm from the end in the longitudinal direction of the continuous film support (that is, one each at both ends in the width direction).
Here, a contact-type thickness measuring device (Fujiwork Corp., S-2270) is used for the measurement. In addition, for the contact-type thickness measuring device, a strip having a width of 5 mm including a position of 5000 mm from the front end or the end in the longitudinal direction of the continuous film support is applied for measurement.

Here, the ratio of the sum of the widths of the knurling parts (w1 + w2 in FIG. 2A) is a continuous film support from the viewpoint of the function manifestation of preventing the shift of the transport position, securing the effective width as a product, and improving the yield. The range of 0.5% to 5.0% is preferable, the range of 0.7% to 4.0% is more preferable, and the range of 1.5% to 3.5% is more preferable with respect to the entire width of the body.

The distance from the end in the width direction of the continuous film support to the knurling portion is preferably 0 mm to 15 mm.
Here, the distance from the end in the width direction of the continuous film support to the knurling portion is the distance from the end in the width direction of the continuous film support to the outer end in the width direction of the knurling portion (distance d in FIG. 2A). Equivalent). That is, the knurling part is preferably formed at a position where the distance d from each end in the width direction of the continuous film support is 0 mm to 15 mm, as shown in FIG. 2A. The distance d from the end in the width direction of the continuous film support to the knurling portion is generally from 0 mm to the point that the knurling portion is easy to form, the effective width as a product is secured, and the yield is improved. It may be 20 mm, preferably 0 mm to 15 mm, more preferably 2 mm to 15 mm.

The protrusion in the knurling portion is formed according to the shape of the convex portion of the knurling roll pressed against the continuous film support when the knurling portion is formed. Examples of the shape of the convex portion of the knurling roll include a truncated pyramid and a truncated cone.
For example, if the shape of the convex portion of the knurling roll is a quadrangular frustum (that is, a shape obtained by cutting the quadrangular pyramid in a plane parallel to the bottom surface and removing the apex-shaped pyramid portion), the continuous film support also has a quadrangular shape. Convex parts (knurling) are formed along the shape.
The convex portion formed on the continuous film support may have a shape in which only the edge of the convex shape of the knurling roll protrudes.

The number of protrusions (knurling) formed on this continuous film support is the point of expression of grip force with respect to a roll such as a temperature control roll, and ensuring the strength of the continuous film support in the region where the knurling part is formed. from the point, when viewed from the top knurled portion in the continuous film support is preferably from ² to 10 to 200 per 1 cm, and more preferably from 80 to 150 per 1 cm ^2.
In addition, observation of this convex part and how to obtain | require the number can be performed with the following method.
That is, since the convex portions are continuously arranged to form the knurling portion, the number of the minimum repeating units is defined as the number of convex portions (also referred to as “convex density”).
The number of convex portions (density of convex portions) is determined at two locations at the front end in the longitudinal direction (that is, one at each end portion in the width direction) and two at the end in the knurling portion of the continuous film support. A total of four places (that is, one at each end in the width direction) are counted by observing a 5 mm square with a 5-fold magnifier, and the average value of each measurement point is multiplied by 4. The obtained value is rounded off to the first decimal place, and this is used as the number of convex portions (convex portion density).
In addition, a measurement location is 5000 mm from the front-end | tip of the longitudinal direction of a continuous film support body, two 5mm square places including each of the both outer ends of the knurling part in the width direction, and the end of the continuous direction of a continuous film support body in the longitudinal direction To 5000 mm, and two locations of 5 mm square each including both outer ends of the knurling portion in the width direction.
In addition, when the width of the knurling part is less than 5 mm, the number of convex parts (convex density) is counted by observing the maximum length four sides each including both outer ends of the knurling part with a 5-fold magnifier. What is necessary is just to convert into the number per 1 cm < ² >. For example, if the width of the knurling part is 3 mm, the number of convex parts (convex density) is counted by observing 3 mm squares at four places with a 5-fold magnifier, and the average value of each measurement part is 100/9 Just double it. The obtained value is rounded off to the first decimal place, and this is used as the number of convex portions (convex portion density).

As shown in FIG. 2A, the knurling portion may be formed by a single band from the longitudinal end to the end of the continuous film support along both ends of the continuous film support. As long as the sum of the widths does not deviate from the above range, a plurality of bands may be formed.

There is no restriction | limiting in particular in the formation method of a knurling part, A well-known knurling apparatus can be used.
As the knurling device, specifically, a device described in JP 2014-2180816 A can be used.

-Application-
A known coating means is applied to the coating.
Specific application methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire. Examples thereof include a coating apparatus using a bar method or the like.

-Dry-
A known drying means is applied for drying.
Specific examples of the drying means include an oven, a warm air machine, and an infrared (IR) heater.
When drying with a warm air machine, it may be configured to apply hot air from the surface opposite to the surface on which the coating liquid of the continuous film support is applied, and diffusion is applied so that the surface of the applied coating liquid does not flow with the hot air. It is good also as a structure which installed the board.
The drying conditions may be determined according to the type of coating solution used, the coating amount, the conveyance speed, etc. For example, it is preferably performed in the range of 30 ° C. to 140 ° C. for 10 seconds to 10 minutes.

Through the above-described coating film forming step, an uncured coating film that is cured by active energy rays is formed.
The thickness of the coating film obtained through the coating film forming step may be determined according to the use of the optical film. If the coating film is a coating film for a liquid crystal layer, which will be described later, the thickness of the coating film after drying (so-called dry film thickness) used in the active energy ray irradiation step is 0.5 μm to 10 μm. Preferably, it is 1 μm to 5 μm.
In the coating film forming step, when a liquid crystal layer coating film to be described later is formed, the film thickness immediately after coating (so-called wet film thickness) is preferably 3 μm to 30 μm, preferably 5 μm to 15 μm. Is more preferable.

[Active energy ray irradiation process]
In the active energy ray irradiation process, the continuous film support on which the coating film is formed is wound around the temperature control roll with the surface having the knurling part, and the coating film on the temperature control roll is irradiated with the active energy ray. To do.

An example of the active energy ray irradiation process will be described with reference to FIG.
As shown in FIG. 1, the continuous film support 10 on which a coating film is formed is wound around a temperature control roll 34. In this region, the coating film on the temperature control roll 34 is activated from the exposure light source 32. Energy rays are irradiated.

When the coating film is irradiated with active energy rays, as shown in FIG. 3, due to the presence of the knurling part 12, the vicinity of the knurling part 12, that is, the width direction end of the continuous film support 10 floats with respect to the temperature control roll. End up. In particular, from the viewpoint of effectively preventing the deviation of the transport position, conventionally, the height of the knurling portion is often about 20 μm. However, when the knurling portion having such a height is provided, the above-described floating is caused. It will be very big.
There is a difference in the irradiation amount of the active energy rays irradiated in the direction of the arrow between the floating portion in the vicinity of the knurling portion 12 and the central portion in the width direction of the continuous film support 10. However, the difference in the irradiation amount of the active energy ray can be reduced by setting the height of the knurling portion to 10 μm or less. In addition, since the height of the knurling portion is 2 μm or more, a function of preventing the shift of the transport position on the temperature control roll 34 can also be obtained.

-Active energy rays-
The active energy ray used in the active energy ray irradiation step is not particularly limited as long as it can impart energy capable of generating active species in the coating film to be irradiated. Specific examples of the active energy ray include α rays, γ rays, X rays, ultraviolet rays, infrared rays, visible rays, and electron beams. Among these, from the viewpoints of curing sensitivity and device availability, the active energy ray used in the active energy ray irradiation step is preferably ultraviolet rays or electron beams, and more preferably ultraviolet rays.

-Exposure light source-
Examples of the exposure light source used for irradiating the active energy ray in the active energy ray irradiating step include the above-described light source that irradiates the active energy ray. From the viewpoint of curing sensitivity and device availability, the exposure light source is preferably a light source that emits ultraviolet rays.
Examples of light sources for irradiating ultraviolet rays include tungsten lamps, halogen lamps, xenon lamps, xenon flash lamps, mercury lamps, mercury xenon lamps, carbon arc lamps, and various lasers (eg, semiconductor lasers, helium neon lasers, Argon ion laser, helium cadmium laser, YAG (Yttrium Aluminum Garnet) laser), light emitting diode, cathode ray tube, and the like can be given.
The peak wavelength of ultraviolet rays emitted from a light source that irradiates ultraviolet rays is preferably 200 nm to 400 nm.

—Temperature control roll The temperature control roll used in the active energy ray irradiation step is not particularly limited, and known ones can be used.
As the temperature control roll, for example, a surface whose surface is hard chrome plated can be preferably used.
The thickness of the plating is preferably 40 μm to 60 μm from the viewpoint of ensuring conductivity and strength.
Further, the surface roughness of the temperature control roll is preferably 0.1 μm or less in terms of surface roughness Ra from the viewpoint of reducing variation in frictional force between the continuous film support and the temperature control roll.

The surface temperature of the temperature control roll may be determined according to the composition of the coating film, the curing performance of the coating film, the heat resistance of the continuous film support, etc., preferably 60 ° C. to 250 ° C., preferably 60 ° C. to 160 ° C. More preferred.
By setting the surface temperature of the temperature control roll to the above temperature, the curing rate of the coating film can be increased, and the temperature of the continuous film support to be wound can be controlled.
The surface temperature of the temperature control roll is measured as follows.
That is, the surface temperature is measured with a radiation thermometer (for example, FT-H30 manufactured by Keyence Corporation) at any five points on the surface of the temperature control roll in the width direction of the temperature control roll. Let the average value of a measured value be the surface temperature of a temperature control roll.

It is preferable that the temperature control roll detects the surface temperature, and the temperature control means maintains the surface temperature of the temperature control roll based on the temperature.
The temperature control means of the temperature control roll includes a heating means and a cooling means. As the heating means, induction heating, water heating, oil heating or the like is used, and as the cooling means, cooling with cooling water is used.

The diameter of the temperature control roll is preferably 100 mm to 1000 mm, and preferably 100 mm to 800 mm from the viewpoint of easy winding of the continuous film support, easy irradiation of active energy rays, and the manufacturing cost of the temperature control roll. More preferably, 200 mm to 700 mm is even more preferable.

In the active energy ray irradiation step, the active energy ray is irradiated on the continuous film support in a stretched state, and therefore the longitudinal direction (that is, the transport direction) with respect to the continuous film support on which the temperature control roll is wound. It is preferable that a tension (also referred to as a tension) is applied to.
The tension applied in the longitudinal direction of the continuous film support on the temperature control roll (ie, tension) is preferably 100 N / m to 600 N / m, more preferably 150 N / m to 500 N / m, and more preferably 300 N / m to 500 N / m. m is more preferable, and 400 N / m to 500 N / m is particularly preferable.
The tension applied in the longitudinal direction of the continuous film support on the temperature control roll (that is, tension) is measured as follows.
That is, on the temperature control roll, the tension sensor provided on the downstream side in the transport direction of the continuous film support (for example, a position 5000 mm away from the separation point between the continuous film support and the temperature control roll) The tension applied in the longitudinal direction of the continuous film support is measured. Here, as the tension sensor, for example, a tension sensor with a built-in load cell is suitable, and specifically, an MB tension sensor manufactured by Nireco Corporation may be used.

The conveying speed of the continuous film support on the temperature control roll is preferably 10 m / min or more and 100 m / min or less from the viewpoint of securing productivity and improving the accuracy of irradiation with active energy rays. More preferably, it is 20 m / min or more and 60 m / min or less.

The wrap angle of the continuous film support relative to the temperature control roll is preferably 60 ° or more, and more preferably 90 ° or more.
The upper limit of the wrap angle is, for example, 180 °.
The wrap angle refers to the transport direction of the continuous film support when the continuous film support contacts the temperature control roll, and the transport direction of the continuous film support when the continuous film support is separated from the temperature control roll. An angle consisting of

Through the above active energy ray irradiation process, the coating film is cured, and a cured film (that is, an optical functional layer) is formed on the continuous film support.

Examples of the optical functional layer formed by the optical film manufacturing method of one embodiment include an optically anisotropic layer in a retardation film, an antireflection layer in an antireflection film, and an antiglare layer in an antiglare film.
That is, according to the method for producing an optical film of one embodiment, a retardation film having an optically anisotropic layer, an antireflection film having an antireflection layer, an antiglare film having an antiglare layer, and the like can be mentioned.

[Method for producing retardation film]
Hereinafter, a method for producing a retardation film will be described as an example of a method for producing an optical film according to an embodiment.
The retardation film is an optically anisotropic layer comprising an alignment layer having an alignment regulating force for aligning the liquid crystal compounds of the liquid crystal layer in a certain direction on a continuous film support, and an aligned and fixed liquid crystal compound , Also referred to as a liquid crystal layer).

(Alignment layer and its formation method)
The alignment layer in the retardation film is not particularly limited as long as the alignment regulating force is given to align the liquid crystal compounds of the liquid crystal layer in a certain direction.
Examples of the alignment layer in the retardation film include an alignment layer to which an alignment regulating force is applied to the liquid crystal compound by a rubbing method, specifically, a layer of an organic compound (preferably a polymer) that has been subjected to a rubbing treatment. it can.
Here, the rubbing method means that the surface of the coating film containing the alignment layer forming material (hereinafter also referred to as alignment layer coating film) is rubbed in a certain direction with a rubbing cloth, whereby the alignment regulation for the liquid crystal compound is applied to the coating film. It is a method that gives power. Moreover, the process which rubs the surface of the coating film for alignment layers in a fixed direction with a rubbing cloth is called a rubbing process.

-Material for alignment layer formation-
The alignment layer forming material used for forming the alignment layer preferably includes an organic compound shown below and a solvent for dissolving the organic compound. Examples of the organic compound include polymethyl methacrylate and acrylic acid / methacrylic acid copolymer. Polymer, styrene / maleimide copolymer, polyvinyl alcohol, poly (N-methylolacrylamide), styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, Examples include vinyl acetate / vinyl chloride copolymers, ethylene / vinyl acetate copolymers, polymers such as carboxymethyl cellulose, polyethylene, polypropylene, and polycarbonate, and compounds such as silane coupling agents.
Examples of preferred polymers include polyimide, polystyrene, polymers of styrene derivatives, polyvir alcohol, and alkyl-modified polyvinyl alcohol having an alkyl group (preferably an alkyl group having 6 or more carbon atoms).
As the polymer used for the alignment layer forming material, an alkyl-modified polyvinyl alcohol is particularly preferable, and an alkyl group having 6 to 14 carbon atoms is represented by —S—, — (CH ₃ ) C (CN) —, or — ( Preference is given to alkyl-modified polyvir alcohols bonded to the ends or side chains of the polyvinyl alcohol via C ₂ H ₅ ) N—CS—S—.

The orientation layer coating film can be the same as the coating method and the drying method in the coating film forming step described above, and the preferred embodiments are also the same.
The film thickness of the alignment layer coating film is preferably 0.1 μm to 5 μm, and more preferably 0.2 μm to 1 μm.

-Give orientation regulation power-
In the case of the rubbing method, the surface of the orientation layer coating film formed on the continuous film support may be rubbed in a certain direction with a rubbing cloth.
There is no restriction | limiting in particular as a rubbing process, A well-known method is applicable. Specifically, the rubbing treatment includes a method in which the surface of the alignment layer coating film is rubbed in a certain direction with a rubbing cloth such as paper, gauze, felt, rubber, nylon, and polyester fiber. In general, a rubbing treatment is performed by rubbing the surface of the alignment layer coating film several times using a rubbing cloth in which fibers of uniform length and thickness are averagely implanted.
As described above, an alignment layer having an alignment regulating force for the liquid crystal compound is formed.

(Liquid crystal layer and its formation method)
On the alignment layer formed as described above, a coating film of a liquid crystal layer forming material (hereinafter also referred to as a coating film for liquid crystal layer) is formed. Thereafter, the liquid crystal compound in the coating film for liquid crystal layer is aligned and fixed, and a liquid crystal layer (that is, an optically anisotropic layer) is obtained.
When the manufacturing method of the optical film of one embodiment is a manufacturing method of a retardation film, the formation of the coating film for the liquid crystal layer corresponds to the above-described coating film forming step, and the formation of the coating film for the liquid crystal layer The liquid crystal layer forming material used corresponds to the active energy ray-curable resin composition.

-Material for forming liquid crystal layer-
The liquid crystal layer forming material contains a rod-like liquid crystal compound or a disk-like liquid crystal compound, and is a material that is cured by active energy rays. In addition to the rod-like liquid crystal compound or the disk-like liquid crystal compound, the liquid crystal layer-forming material may be a known other such as a polymerizable compound, a crosslinkable compound, a chiral agent, an alignment controller, a polymerization initiator, an alignment aid, etc. The component may be contained.

-Rod-like liquid crystal compounds As rod-like liquid crystal compounds, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted compounds Phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used.

The rod-like liquid crystal compound is more preferably fixed in orientation by polymerization, and therefore, a rod-like liquid crystal compound having a polymerizable group is preferably used.
Examples of the rod-like liquid crystal compound having polymerizability include Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, International Publication Nos. 95/22586, 95 No. / 24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469, No. 11- And compounds described in JP-A-80081 and JP-A-2001-328773.
Further, as the rod-like liquid crystal compound, for example, those described in JP-T-11-513019, JP-A-2007-279688 and the like can be preferably used.

-Discotic liquid crystal compound As the discotic liquid crystal compound, for example, those described in JP-A-2007-108732, JP-A-2010-244038 and the like can be preferably used.

As the coating film for the liquid crystal layer, the same methods as the coating method and the drying method in the above-described coating film forming step can be used, and the preferred embodiments are also the same.

-Orientation of liquid crystal compounds-
Before fixing the alignment of the liquid crystal compound in the liquid crystal layer coating film, it is preferable to perform an alignment treatment of the liquid crystal compound in the liquid crystal layer coating film.
The alignment treatment can be performed by drying at room temperature or by heating.
In the case of a thermotropic liquid crystal compound, the liquid crystal formed by the alignment treatment can generally be transferred by a change in temperature or pressure. Further, in the case of a liquid crystal compound having lyotropic properties, it can be transferred also by a composition ratio such as the amount of solvent.

When the rod-like liquid crystal compound develops a smectic phase, the temperature region in which the nematic phase develops is usually higher than the temperature region in which the rod-like liquid crystal compound develops a smectic phase. Therefore, the rod-like liquid crystal compound is heated to a temperature range where the rod-like liquid crystal compound develops a nematic phase, and then the heating temperature is lowered to a temperature region where the rod-like liquid crystal compound develops a smectic phase, thereby bringing the rod-like liquid crystal compound into a nematic phase. To a smectic phase. By setting it as a smectic phase by such a method, a liquid crystal in which liquid crystal compounds are aligned with a high degree of order can be obtained.

In the temperature range where the rod-like liquid crystal compound develops a nematic phase, it is necessary to heat for a certain time until the rod-like liquid crystal compound forms a monodomain. The heating time is preferably 10 seconds to 5 minutes, more preferably 10 seconds to 3 minutes, and most preferably 10 seconds to 2 minutes.
In the temperature range where the rod-like liquid crystal compound develops a smectic phase, it is necessary to heat for a certain time until the rod-like liquid crystal compound develops a smectic phase. The heating time is preferably 10 seconds to 5 minutes, more preferably 10 seconds to 3 minutes, and most preferably 10 seconds to 2 minutes.

The alignment of the liquid crystal compound may be performed by drying when forming the coating film for the liquid crystal layer. That is, you may perform both drying of the liquid crystal layer forming material apply | coated on the orientation layer, and orientation of a liquid crystal compound by drying at the time of forming with the coating film for liquid crystal layers.
Of course, the alignment of the liquid crystal compound may be performed separately from the drying for forming the coating film for the liquid crystal layer.

-Fixing the alignment of liquid crystal compounds-
It is preferable to fix the orientation of the liquid crystal compound in the coating film for the liquid crystal layer by curing the coating film for the liquid crystal layer by thermal polymerization or polymerization by active energy rays.
When the manufacturing method of the optical film of one embodiment is a manufacturing method of a retardation film, fixing of the orientation of the liquid crystal compound using active energy rays corresponds to the active energy ray irradiation step described above.
When a polymerizable liquid crystal compound is used, if the irradiation amount of the active energy ray is small, an unpolymerized liquid crystal compound remains, which causes a change in temperature of optical characteristics, deterioration with time, and the like. Therefore, it is preferable to determine the irradiation conditions so that the ratio of the remaining unpolymerized liquid crystal compound is 5% or less.
Irradiation conditions depend on the formulation of the material for forming the liquid crystal layer and the thickness of the coating film for the liquid crystal layer, but the active energy ray dose is preferably 50 mJ / cm ² to 1000 mJ / cm ² , and preferably 100 mJ / cm ² to 100 mJ / cm ² . 500 mJ / cm ² is more preferable.

As the light source used for the irradiation of the active energy ray, the exposure light source in the coating film forming step described above can be applied, and the preferred embodiment is the same.

In addition, the details of the liquid crystal layer can be referred to the descriptions in JP-A-2008-225281 and JP-A-2008-026730.

The retardation film obtained as described above has little variation in optical characteristics (for example, retardation) in the width direction.
Therefore, a retardation film excellent in in-plane uniformity of optical characteristics (for example, retardation) can be obtained.

As mentioned above, when obtaining the liquid crystal layer of the retardation film, the example of applying the method for producing the optical film of one embodiment has been described. In addition, the above-described antireflection layer of the antireflection film, antiglare film, It can also be applied when obtaining an antiglare layer or the like.

Hereinafter, the present invention will be described more specifically with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

<Continuous film support having a knurling part>
[Continuous film support (1) to (10)]
A continuous film support (cellulose triacetate film TJ40, FUJIFILM Corporation) on which the knurling part shown in Table 1 below was formed was prepared.
The prepared continuous film support had a total width of 1.3 m and a length of 1000 m.
In Table 1, “the number of bands” means the number of bands formed by the knurling portion formed from one longitudinal end of the continuous film support to the end along one end in the width direction of the continuous film support. The “convex density” means the number of convex portions per 1 cm ² when the knurling portion in the continuous film support is viewed from above, and the “film thickness” is the thickness of the continuous film support. The thickness of the location where the knurling part is not formed is shown.
In addition, No. 1 in Table 1 below. The continuous film support (4) refers to one in which a knurling part is not formed.

[Measurement of knurling part]
With respect to the continuous film supports (1) to (3) and (5) to (10), the height of the knurling part and the number of convex parts (“convex density”) were measured as described above.
The measurement results are shown in Table 1.

[Example 1]
(Formation of alignment layer coating and rubbing treatment)
On the surface opposite to the surface having knurling portion of the continuous film support (1), alkyl-modified polyvinyl alcohol (Poval MP-203, Kuraray Co., Ltd.) 2% by weight aqueous solution of a continuous film support 1 m ² per 25ml after application By drying at 60 ° C. for 60 seconds, an alignment layer coating film having a dry film thickness of 0.5 μm was formed. The surface of the alignment layer coating film is rubbed while the continuous film support on which the alignment layer coating film is formed is conveyed at a conveyance speed of 30 m / min to form an alignment film having a thickness of 0.5 μm. did.

(Formation of coating film for liquid crystal layer: coating film forming process)
Then, the coating film formation process and the active energy ray irradiation process were performed with the apparatus comprised as shown in FIG.
Specifically, a liquid crystal layer forming material prepared with the following composition was applied onto the alignment layer using a bar coater.
The continuous film support coated with the liquid crystal layer forming material was dried by heating at a film surface temperature of 150 ° C. for 60 seconds to form a liquid crystal layer coating film having a dry film thickness of 3 μm.

-Composition of liquid crystal layer forming material-
The following reverse wavelength dispersion liquid crystal compound R-2: 100 parts by mass Photopolymerization initiator: 3.0 parts by mass (Irgacure 819, BASF)
The following fluorine-containing compound A: 0.8 part by mass The following crosslinkable polymer O-2 (Tg: 10 ° C.): 0.3 part by mass Chloroform: 588 parts by mass

(UV irradiation: active energy ray irradiation process)
Subsequently, a continuous film support on which a coating film for a liquid crystal layer is formed is wrapped on a temperature control roll (diameter: 500 mm, material stainless steel) having a surface temperature of 120 ° C., and a surface having a knurling portion is brought into contact with the temperature control roll. Wrapped around 90 ° C. And the ultraviolet-ray was irradiated with respect to the coating film for liquid crystal layers of the wound area | region using the air-cooled metal halide lamp (eye graphics company). The irradiation amount of ultraviolet rays was 300 mJ / cm ² .
Here, the tension | tensile_strength applied to the longitudinal direction of the continuous film support body in which the coating film for liquid crystal layers on the temperature control roll was formed was 330 N / m.

As described above, the orientation of the liquid crystal compound was fixed and a liquid crystal layer was formed to obtain a retardation film.

[Examples 2 to 3, Examples 7 to 10, and Comparative Examples 1 to 3]
A retardation film was produced in the same manner as in Example 1 except that the continuous film support (1) was replaced with any of the continuous film supports (2) to (10) shown in Table 2 below.

[Example 4]
A retardation film was produced in the same manner as in Example 1 except that the continuous film support (1) was replaced with the continuous film support (2) and the surface temperature of the temperature control roll was changed to 60 ° C.

[Examples 5 and 6]
The continuous film support (1) is replaced with the continuous film support (2), and the tension applied in the longitudinal direction of the continuous film support on which the coating film for the liquid crystal layer is formed on the temperature control roll is shown in Table 2 below. A retardation film was produced in the same manner as in Example 1 except that the value was set to.

[Evaluation: Evaluation of variation in optical characteristics]
About the retardation film produced in the said Example and comparative example, the variation in the optical characteristic in the width direction was evaluated based on the following method and evaluation criteria. The results are shown in Table 2.

(Evaluation 1: Evaluation of variation in optical characteristics due to deviation in transport position)
13 points in the width direction (specifically, from one end in the width direction) at three locations of 1 m, 500 m, and 999 m in the longitudinal direction from the end of the obtained retardation film (that is, the end on the winding end side) Retardation was measured for 6 points at 100 mm intervals, 1 point at 50 mm intervals, 1 point at 50 mm intervals, and then 5 points at 100 mm intervals.
The difference between the maximum value and the minimum value was determined from the measured values of the retardation at 13 points in the width direction, and the maximum difference among the above three locations was used as an evaluation target. The greater the difference, the greater the variation in optical characteristics in the width direction caused by the shift in the transport position, and the practical allowable range is up to 5 nm.
For the measurement of retardation, an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments) was used.

(Evaluation 2: Evaluation of variation in optical characteristics due to floating)
Moreover, the retardation was measured about the width direction terminal of 1 m, 500 m, and 999 m from the terminal (namely, end part of winding end side) of the obtained retardation film to a longitudinal direction.
In the case of the retardation film using the continuous film supports (1) to (6), (9), and (10), the end in the width direction for measuring the retardation is 17 mm from the end in the width direction. Position, in the case of a retardation film using a continuous film support (7), 20 mm from the end in the width direction, in the case of a retardation film using a continuous film support (8), from the end in the width direction The position was 25 mm.
The difference (absolute value) between the measured value of retardation at the end in the width direction at the same three positions and the average value of the measured value of retardation at 13 points in the width direction measured in Evaluation 1 Each was obtained, and this difference was the largest and was evaluated. The greater the difference, the greater the variation in optical characteristics in the width direction due to floating, and the practical tolerance is up to 5 nm.
For the measurement of retardation, an automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments) was used.

As is clear from Table 2, it can be seen that the retardation films of the examples have less variation in optical characteristics in the width direction than the retardation films of the comparative examples.

[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Application | coating means 2 Drying means 10 Continuous film support body 12 Knurling part 32 Exposure light source 34 Temperature control roll d Distance from each edge part of width direction of continuous film support body of knurling part w1, w2 Width of knurling part

The disclosure of Japanese application 2018-062708 filed on March 28, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims

An active energy ray-curable resin composition is applied and dried on the surface opposite to the surface having the knurling portion of the continuous film support having a knurling portion having a height of 2 μm to 10 μm along both ends in the width direction. Forming, and
Wrapping the continuous film support on which the coating film is formed by bringing the surface having the knurling part into contact with the temperature control roll, irradiating the coating film on the temperature control roll with active energy rays,
The manufacturing method of the optical film which has this.
The method for producing an optical film according to claim 1, wherein the tension applied in the longitudinal direction of the continuous film support on which the coating film is formed on the temperature control roll is 150 N / m to 500 N / m.
The method for producing an optical film according to claim 1 or 2, wherein the surface temperature of the temperature control roll is 60 ° C to 160 ° C.
The method for producing an optical film according to any one of claims 1 to 3, wherein a ratio of a sum of widths of the knurling portion to a full width of the continuous film support is 0.5% to 5.0%.
The method for producing an optical film according to any one of claims 1 to 4, wherein a distance from an end portion in the width direction of the continuous film support to the knurling portion is 0 mm to 15 mm.
The method for producing an optical film according to any one of claims 1 to 5, wherein a thickness of a portion where the knurling portion of the continuous film support is not formed is 20 袖 m to 100 袖 m.