JPWO2019159973A1 - Phase difference film manufacturing method and retardation film manufacturing equipment - Google Patents

Abstract

A step of applying a material for forming an alignment layer to a continuous film support that is continuously conveyed and drying it to form a first coating film, and a backup roll in which the in-plane deviation of the front reflectance of the surface is 1 percentage point or less. A step of irradiating the first coating film with polarized ultraviolet rays while the continuous film support is wound around the liquid crystal to form an alignment layer having an orientation regulating force on the liquid crystal compound, and a liquid crystal compound on the alignment layer. A step of applying and drying the material for forming a liquid crystal layer containing the liquid crystal layer to form a second coating film, and a step of orienting the liquid crystal compound in the second coating film and fixing the orientation to form a liquid crystal layer. It is a method for producing a retardation film and an apparatus for producing a retardation film.

Description

The present disclosure relates to a method for producing a retardation film and an apparatus for producing a retardation film.

As a retardation film used for a liquid crystal display or the like, one in which an alignment layer and a liquid crystal layer are provided on a support is known.
The alignment layer is a layer having an orientation regulating force for arranging the liquid crystal compounds of the liquid crystal layer in a certain direction.

In order to improve productivity, the retardation film is produced by a continuous process in a roll-to-roll method using a continuous film support.
When producing a retardation film by the roll-to-roll method, in recent years, the photo-alignment method has tended to be adopted instead of the conventional rubbing process as a means for imparting a restrictive force to the orientation of the liquid crystal. In the photo-alignment method, orientation is controlled by irradiating polarized ultraviolet rays after applying the alignment layer, and when the liquid crystal layer is applied in the next step, the liquid crystals are arranged in a desired direction.

As an embodiment of irradiating the polarized ultraviolet rays by the photoalignment method, there is an embodiment of irradiating the coating film of the alignment layer forming material with the polarized ultraviolet rays on the backup roll. In this aspect, the coating film can be irradiated with polarized light on the continuous film support stretched along the shape of the backup roll, and the continuous film support is in contact with the backup roll, so that the continuous film support is provided. It is effective in that the temperature of the body and the coating film can be easily controlled.

As an example of using the photo-alignment method, Japanese Patent Application Laid-Open No. 2002-99869 describes a method for producing a photo-alignment layer, which comprises a step of applying a photo-alignment layer on a support and then irradiating the photo-alignment layer with polarized ultraviolet rays. A method for producing a photo-aligned layer in which the amplitude of the support is within 10 mm in the transport direction or the width direction of the support within the irradiation area of polarized ultraviolet rays on the support is disclosed.

As an example of irradiating the oriented layer with polarized ultraviolet rays on the backup roll, Japanese Patent Application Laid-Open No. 2014-170238 states that at least one of the first exposure process and the second exposure process included in the exposure step is a transport roll (backup). A method of irradiating an alignment layer with a pattern of polarized ultraviolet rays on a roll) to produce a pattern alignment film having a color that does not reflect polarized ultraviolet rays on the surface of a transport roll is disclosed.

Here, in order for the liquid crystal compounds in the liquid crystal layer formed on the alignment layer to be regularly arranged according to the orientation of the alignment layer, it is considered important that the alignment layer has excellent uniformity of the orientation axis. There is. In the photo-alignment method, polarized ultraviolet rays (also referred to as polarized ultraviolet rays in the present specification) are irradiated to the alignment layer, but in order to realize good uniformity of the orientation axis, the irradiation amount of polarized ultraviolet rays is constant. It is required that the value is equal to or more than the value of and that the incident angle distribution is uniform.

Of these, the irradiation amount is considered to maintain uniformity as long as it satisfies a value that changes depending on the type of the material for forming the alignment layer and the cured state. On the other hand, with respect to the incident angle distribution, even a slight change in irradiation conditions (irradiation amount, irradiation angle, etc.) tends to disturb the uniformity, and it becomes difficult to form an orientation layer having a uniform orientation axis.
For example, the polarized ultraviolet light applied to the alignment layer passes through the continuous film support and is reflected on the surface of the backup roll, and is reflected on the surface of the backup roll (in the present specification, it may be referred to as reflected light). As a result, the alignment layer is irradiated, which may disturb the uniformity of the alignment axis.
In addition, changes in the surface condition due to rust or dirt on the surface of the backup roll caused by continuous use of the backup roll also affect the reflected light, resulting in a state in which the distribution of the incident angle differs depending on the location of the orientation layer. It may cause a loss of shaft uniformity.

In Japanese Patent Application Laid-Open No. 2002-99869, in order to suppress the variation in the orientation axis, the variation in the irradiation direction or the irradiation angle is set to within 5 ° by adjusting the amplitude of the support during transportation within 10 mm. Although there is a description, the irradiation conditions other than the variation in the irradiation angle have not been examined, and it is considered that good uniformity of the orientation axis has not been realized.
Further, in Japanese Patent Application Laid-Open No. 2014-170238, it is described that the surface of the backup roll is a color that does not reflect polarized ultraviolet rays, but the influence of the reflected light on the orientation axis has not been examined at all.
Further, in Japanese Patent Application Laid-Open No. 2002-99869 and Japanese Patent Application Laid-Open No. 2014-170238, the influence of changes in the surface state due to rust or dirt generated when the backup roll is continuously used on the reflected light is considered. However, it is considered that the problem of non-uniformity of the orientation axis as described above occurs over time.

An object to be solved by one embodiment of the present disclosure is to provide a method for producing a retardation film for producing a retardation film having excellent uniformity of orientation axes.
Another object to be solved by another embodiment of the present disclosure is to provide a retardation film manufacturing apparatus for manufacturing a retardation film having excellent uniformity of orientation axes.

Specific means for solving the above problems include the following aspects.
<1> A step of applying and drying a material for forming an orientation layer on a continuous film support that is continuously conveyed to form a first coating film, and an in-plane deviation of the front reflectance of the surface (hereinafter, surface reflectance). A continuous film support is wound around a backup roll having a deviation of 1 percentage point or less, and the first coating film is irradiated with polarized ultraviolet rays to provide orientation with an orientation regulating force for the liquid crystal compound. A step of forming a layer, a step of applying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer and drying to form a second coating film, and a step of orienting the liquid crystal compound in the second coating film are performed. This is a method for producing a retardation film having a step of fixing the orientation and forming a liquid crystal layer.
<2> The method for producing a retardation film according to <1>, wherein the surface of the backup roll is a mirror surface.
<3> The method for producing a retardation film according to <1> or <2>, wherein the backup roll has an absorption rate of 60% to 99.95% for ultraviolet rays having a wavelength of 300 nm to 380 nm.
<4> The method for producing a retardation film according to any one of <1> to <3>, wherein the material of the backup roll is stainless steel or the surface of the backup roll is black.
<5> The method for producing a retardation film according to any one of <1> to <4>, which includes a step of removing deposits on the surface of the backup roll.
<6> The removal is the method for producing a retardation film according to <5>, which is performed using a deposit removing device.
<7> The deposit removing device is the method for manufacturing a retardation film according to <6>, which is a deposit removing roll, a blower, a wiper, or a dipping washer.
<8> A first coating means for applying a material for forming an alignment layer to a continuous film support that is continuously conveyed, and a first coating method for forming a first coating film by drying the material for forming an alignment layer after coating. The drying means, the backup roll having a surface reflectance deviation of 1 percentage point or less, and the first coating film being irradiated with ultraviolet rays with the continuous film support wrapped around the backup roll to regulate the orientation of the liquid crystal compound. The alignment layer forming means for forming the alignment layer having force, the second coating means for applying the liquid crystal layer forming material containing the liquid crystal compound on the alignment layer, and the liquid crystal layer forming material after coating are dried. A device for producing a retardation film, comprising a second drying means for forming a second coating film, and a liquid crystal layer forming means for orienting a dried liquid crystal compound and fixing the orientation to form a liquid crystal layer. Is.

According to one embodiment of the present disclosure, it is possible to provide a method for producing a retardation film for producing a retardation film having excellent uniformity of orientation axes.
Further, according to another embodiment of the present disclosure, it is possible to provide a retardation film manufacturing apparatus for manufacturing a retardation film having excellent uniformity of orientation axes.

FIG. 1 is a schematic view showing each step of the method for manufacturing a retardation film according to an embodiment of the present disclosure. FIG. 2 is an enlarged view of a main part when irradiating polarized ultraviolet rays in the method for producing a retardation film according to the embodiment of the present disclosure. FIG. 3 is a plan view showing the arrangement of the wire grid of the wire grid polarizer. FIG. 4 is a diagram illustrating an irradiation angle when irradiating polarized ultraviolet rays.

In the present specification, the numerical range indicated by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value, respectively. In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Further, in the numerical range 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 value shown in the examples.
In the present disclosure, the term "process" is included in the term not only in an independent process but also in the case where the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

≪Manufacturing method of retardation film≫
The method for producing a retardation film of the present disclosure is a step of applying and drying a material for forming an alignment layer on a continuous film support that is continuously conveyed to form a first coating film (hereinafter, a first coating film forming step). The first coating film is irradiated with polarized ultraviolet rays in a state where the continuous film support is wound around a backup roll having a surface reflectance deviation of 1 percentage point or less, and the orientation regulating force for the liquid crystal compound is applied. A step of forming an alignment layer provided with (hereinafter referred to as an alignment layer forming step) and a step of applying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer and drying to form a second coating film (hereinafter referred to as an alignment layer forming step). Hereinafter, a second coating film forming step) and a step of orienting the liquid crystal compound in the second coating film and fixing the orientation to form a liquid crystal layer (hereinafter referred to as a liquid crystal layer forming step). It is a manufacturing method of a retardation film having.

The retardation film is manufactured by a roll-to-roll continuous process using a continuous film support in order to improve productivity.
Among the above-mentioned prior arts, Japanese Patent Application Laid-Open No. 2002-99869 considers that when the coating film of the material for forming an alignment layer is irradiated with polarized ultraviolet rays on a backup roll, the irradiation angle is within a specific range. However, it is considered that the uniformity of the orientation axis is inferior. Japanese Patent Application Laid-Open No. 2014-170238 has not been examined at all from the viewpoint of realizing a uniform irradiation amount of reflected light, so that the uniformity of the orientation axis cannot be expected.
Further, with the conventional technique, it is not possible to solve the disorder of the orientation axis due to the roll surface state that deteriorates with time after the start of production.

Therefore, the present inventors have found that the influence of the light reflected on the surface of the backup roll on the orientation axis can be eliminated by setting the surface reflectance deviation of the backup roll to 1 percentage point or less. That is, if the surface reflectance deviation of the backup roll is 1 percentage point or more, the irradiation amount of the reflected light applied to the alignment layer is not constant, which is considered to be a factor that impairs the uniformity of the alignment axis. Therefore, by setting the surface reflectance deviation of the backup roll to 1 percentage point or less, it is possible to suppress the variation in the irradiation amount of the light reflected on the surface of the backup roll, which is applied to the alignment layer, and the incident angle distribution is uniform. As a result, the uniformity of the orientation axis of the liquid crystal compound in the alignment layer can be remarkably improved.

By making the surface reflectance of the backup roll uniform in the roll surface, the irradiation amount of the reflected light applied to the alignment layer is made uniform, so that the variation of the alignment axis can be suppressed and the uniform alignment axis can be suppressed. A method for producing a retardation film having the above can be provided.

First, a method for manufacturing a retardation film will be described.
[First coating film forming step]
The method for producing a retardation film includes a first coating film forming step of applying and drying a material for forming an alignment layer on a continuous film support that is continuously conveyed to form a first coating film.
An example of the first coating film forming step will be described with reference to FIG.
As shown in FIG. 1, when the tip of the wound continuous film support 50 is sent out, the alignment layer forming material is first applied by the alignment layer forming material coating means 1, and then the alignment layer forming material is applied. The material for forming the alignment layer is dried in the drying region by the drying means 2. As a result, a first coating film is formed on the continuous film support.

-Continuous film support-
As the continuous film support, it is preferable to use a long polymer film that can be wrapped around a backup roll. Here, "continuous" means having a long shape unlike a foliage-shaped sheet.
Examples of polymer film materials used as continuous film supports include cellulose acylates (eg, cellulose triacetate (triacetyl cellulose, 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 polyether sulfone and polymethyl methacrylate, polyurethane, polycarbonate, polysulfone, polyether, polymethylpentene, polyether ketone, poly ( Meta) Acrylic nitrile, polymer having an alicyclic structure (for example, norbornene resin (trade name "Arton (registered trademark)", JSR), amorphous polyolefin (for example, trade name "Zeonex (registered trademark)", (Made by Nippon Zeon Co., Ltd.))).
Of these, triacetyl cellulose, polyethylene terephthalate (PET), and a polymer having an alicyclic structure are preferable, and triacetyl cellulose is particularly preferable.

The thickness of the continuous film support is preferably in the range of 10 μm to 250 μm, and the thin continuous film support is disadvantageous in transport stability. Therefore, from the viewpoint of transport stability, 15 μm or more is more preferable. From the viewpoint of cost, 150 μm or less is more preferable.
In particular, the method for producing a retardation film of the present disclosure can preferably use a continuous film support having a thickness in the range of 30 μm to 120 μm, which tends to cause in-plane variation in the elongation amount of the continuous film support.

-Material for forming an orientation layer-
Examples of the material for forming the alignment layer used for forming the alignment layer include JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, and special publications. Kai 2007-121721, JP-A-2007-140465, JP-A-2007-156439, JP-A-2007-133184, JP-A-2009-109831, Patent No. 3883848, Patent No. 4151746 The azo compound described in JP-A-2002-229039, the aromatic ester compound described in JP-A-2002-265541, a polyfunctional maleimide derivative having a structural unit exhibiting photoorientity and an alkenyl-substituted nadiimide compound described in JP-A-2002-265541. A polymerizable monomer having a photo-oriented group and a polymerizable maleimide group described in JP-A-2002-317713, a photocrosslinkable silane derivative described in Japanese Patent No. 4205195 and Japanese Patent No. 4205198. Photocrossable polyimides, polyamic acids, or esters thereof described in JP-A-2003-520878, JP-A-2004-522220, and Patent No. 4162850, JP-A-9-118717, JP-A-10-506420. Photodimerizable compounds (particularly, synnamate compounds and chalcone compounds) described in JP-A-2003-505561, International Publication No. 2010/150748, JP-A-2013-177561, and JP-A-2014-12823. , Or a coumarin compound) and the like.
Among these, particularly preferable examples include the azo compound described in the above publication, the photocrosslinkable polyimide, polyamide, or an ester thereof described in the above publication, the synnamate compound described in the above publication, the chalcone compound and the like.

-Applying-
A known coating device can be applied to the coating means 1 of the material for forming an oriented layer.
Specific examples of the coating device include curtain coating method, dip coating method, spin coating method, printing coating method, spray coating method, slot coating method, roll coating method, slide coating method, blade coating method, gravure coating method, and wire. An example is a coating device using the bar method or the like.

− Drying −
A known drying device can be applied to the drying means 2 of the material for forming an oriented layer.
Specific examples of the drying device include an oven, a blower, an infrared (IR) heater, and the like.
In the case of using a blower, warm air may be blown from the surface of the continuous film support opposite to the surface on which the material for forming the alignment layer is applied to dry the film, and the surface of the material for forming the oriented layer is warm. A diffusion plate may be installed so as not to flow by the wind, and the warm air may be diffused and dried by applying it to the coated surface.
The drying conditions may be determined according to the type of the material for forming the alignment layer used, the coating amount, the transport speed, and the like. For example, the drying conditions are preferably carried out in the range of 30 ° C. to 140 ° C. for 10 seconds to 10 minutes.

As described above, the first coating film is formed.
The dry film thickness of the formed first coating film is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 1 μm.

[Orientation layer forming step]
In the method for producing a retardation film, after the first coating film forming step, polarized ultraviolet rays are applied to the first coating film in a state where a continuous film support is wound around a backup roll having a surface reflectance deviation of 1 percentage point or less. It has an alignment layer forming step of irradiating to form an alignment layer having an orientation regulating force for a liquid crystal compound.
An example of the alignment layer forming step will be described with reference to FIG.
As shown in FIG. 1, after the first coating film is formed on the continuous film support 50, the continuous film support 50 is wound around the backup roll 40, and the wound continuous film support 50 is wound. The first coating film is irradiated with polarized ultraviolet rays by the photoaligning device 60.
In the alignment layer forming step, the surface of the continuous film support opposite to the surface on which the first coating film is formed in the first coating film forming step is brought into contact with the backup roll.

The irradiation of polarized ultraviolet rays in the alignment layer forming step will be described with reference to FIGS. 2 to 4.
As shown in FIG. 2, the optical alignment device 60 is arranged so as to face the backup roll 40, and is arranged in the region of the continuous film support 50 conveyed in the Y direction, which is wound around the backup roll 40. The first coating film is irradiated with polarized ultraviolet rays by the photoaligning device 60.

-Backup roll-
The backup roll in the present disclosure has a surface reflectance deviation (sometimes referred to as surface reflectance in the present specification) of 1 percentage point or less. When the surface reflectance deviation is 1 percentage point or less, the uniformity of the reflected light is good, so that the variation in the irradiation amount of the reflected light to the alignment layer is reduced, and the uniformity of the alignment axis can be improved.
The surface reflectance deviation of the backup roll is preferably 0.5 percentage point or less.

For the surface reflectance of the backup roll, measurement points are taken at a pitch of 10 mm in the roll width direction of the backup roll at 12 points where the backup roll is divided into 12 in the circumferential direction, and the front reflectance (front reflectance) for light having a wavelength of 365 nm at each measurement point. %) Is measured.
A spectrophotometer (MV-3100, manufactured by JASCO Corporation) is used to measure the surface reflectance of the backup roll.
The in-plane deviation of the surface reflectance of the backup roll is represented by the difference (percent point) between the maximum value and the minimum value of the surface reflectance measured as described above. The larger this difference is, the larger the variation in the surface reflectance of the backup roll in the surface of the roll is.

The surface reflectance deviation of the backup roll can be adjusted by polishing the roll surface.

The absorption rate of the backup roll for ultraviolet rays having a wavelength of 300 nm to 380 nm is preferably 60% to 99.95%. When the absorption rate is 99.95% or less, it is advantageous in that the reflected light can be effectively used for the orientation of the alignment layer. When the absorption rate is 60% or more, the irradiation amount of the reflected light applied to the coating film itself can be suppressed, and the influence on the orientation axis due to the variation in the irradiation amount can be reduced.
The absorption rate of the backup roll for ultraviolet rays having a wavelength of 300 nm to 380 nm is more preferably 99.5% to 99.95%, further preferably 99.9% to 99.95%.

For the reflectance of the backup roll to ultraviolet rays with a wavelength of 300 nm to 380 nm, first, measurement points are taken at a pitch of 10 mm in the roll width direction of the backup roll at 12 points where the backup roll is divided into 12 in the circumferential direction, and the wavelength at each measurement point is 300 nm. The reflectance to ultraviolet rays of ~ 380 nm was measured with a spectrophotometer (for example, MV-3100 manufactured by JASCO Corporation), and the average value was calculated by averaging each measured value, and the calculated average value of the reflectance was calculated. It is a value obtained by subtracting from 1.

The absorption rate of the backup roll for ultraviolet rays having a wavelength of 300 nm to 380 nm can be adjusted by selecting the material of the film covering the roll surface or the type of the base material of the roll body.

As the backup roll in the present disclosure, any known backup roll can be used without particular limitation as long as the surface reflectance deviation is 1 percentage point or less.
As the backup roll, for example, one having a hard chrome-plated surface can be preferably used.
The thickness of the plating is preferably 40 μm to 60 μm from the viewpoint of ensuring conductivity and strength.

The material of the backup roll is not particularly limited, and examples thereof include stainless steel from the viewpoint of the absorption rate for ultraviolet rays having a wavelength of 300 nm to 380 nm.

Specifically, SUS304 can be used as the type of stainless steel.
SUS (Steel Special Use Stainless) is a stainless steel material, which is a special steel made by adding substances such as chromium and nickel to iron to prevent rusting.

As the backup roll, surface-treated or plated stainless steel may be used. For example, stainless steel surface-treated with black alumite, black chrome, or the like can be mentioned. Of these, stainless steel surface-treated with black alumite is preferable from the viewpoint of absorption rate against ultraviolet rays having a wavelength of 300 nm to 380 nm.

The surface of the backup roll is preferably a mirror surface from the viewpoint that the reflectance of ultraviolet rays on the surface of the backup roll can be made uniform.
At that time, the surface roughness of the backup roll is 0 in terms of surface roughness (Ra) from the viewpoint of reducing the variation in the frictional force between the continuous film support and the backup roll and the surface reflectance deviation of the backup roll. It is preferably 0.05 μm or less.
The surface roughness (Ra) is a value measured by a method conforming to JIS B0601 (2001) using a surface roughness measuring instrument (SJ-310, manufactured by Mitutoyo Co., Ltd.).

The surface color of the backup roll is preferably black or gray, and more preferably black, from the viewpoint of the absorption rate of the surface of the backup roll with respect to ultraviolet rays having a wavelength of 300 nm to 380 nm.

The temperature of the backup roll is preferably maintained at 25 ° C to 100 ° C, more preferably 25 ° C to 50 ° C.
By maintaining the backup roll at the above temperature, the temperature of the continuous film support to be wound can be controlled.

It is preferable that the backup roll detects the surface temperature and the surface temperature of the backup roll is maintained by the temperature control means based on the temperature.
Examples of the temperature control means for the backup roll include means using induction heating, water heating, oil heating and the like for heating means, and means using cooling water for cooling means.

The diameter of the backup roll is preferably 100 mm to 1000 mm, more preferably 100 mm to 800 mm, from the viewpoints of easy winding of the continuous film support, easy irradiation of polarized ultraviolet rays, and manufacturing cost of the backup roll. More preferably, it is 200 mm to 700 mm.

In the alignment layer forming step, since the continuous film support in a stretched state is irradiated with polarized ultraviolet rays, tension is applied to the continuous film support around which the backup roll is wound in the transport direction.
The width (Fw2) of the continuous film support when tension is applied is smaller than the width (Fw1) when tension is not applied.
The shrinkage ratio of the width of the continuous film support on the backup roll is obtained from the following equation (1), in order to further suppress the meandering of the continuous film support and to suppress the deformation of the continuous film support. , 0.06% to 1.20%, more preferably 0.08% to 0.35%.
Equation (1) Shrinkage rate (%) = (Fw1-Fw2) / Fw1 × 100
(Fw1 indicates the width of the continuous film support when tension is not applied, and Fw2 indicates the width of the continuous film support when tension is applied on the backup roll.)
Tension may be applied to the continuous film support on the backup roll so that the shrinkage ratio is as described above. Specifically, in order to achieve the above shrinkage ratio, the tension applied to the continuous film support on the backup roll is preferably 120 N / m to 720 N / m.

The transport speed of the continuous film support on the backup roll is preferably 10 m / min or more and 100 m / min or less, preferably 20 m, from the viewpoint of ensuring productivity and improving the accuracy of irradiation with polarized ultraviolet rays. It is preferably / min or more and 60 m / min or less.

The wrap angle of the continuous film support with respect to the backup roll is preferably 60 ° or more, more preferably 90 ° or more.
The lap angle is defined as the transport direction of the continuous film support when the continuous film support comes into contact with the backup roll and the transport direction of the continuous film support when the continuous film support is separated from the backup roll. The angle that becomes.

-Light alignment device-
The optical alignment device 60 includes a rod-shaped light source 10, a concave reflector 11 that efficiently reflects the light from the rod-shaped light source 10 in the vertical direction toward the wire grid polarizer 30, and a plurality of rod-shaped light sources 10 arranged in the longitudinal direction. It is composed of a louver 20 made of a parallel plate 21 and a wire grid polarizer 30 that linearly polarizes the light parallelized by the louver 20.
Then, the polarized ultraviolet rays emitted from the wire grid polarizer 30 are applied to the first coating film.

-Bar-shaped light source As the bar-shaped light source 10, for example, a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, a mercury xenon lamp, a carbon arc lamp or the like, and various lasers (eg, a semiconductor laser, a helium neon laser) , Argon ion laser, helium cadmium laser, YAG (Ytrium Aluminum Garnet) laser), light emitting diode, cathode wire tube and the like.
The peak wavelength of ultraviolet rays emitted from the rod-shaped light source 10 is preferably 200 nm to 400 nm.
The wavelength can be appropriately selected according to the absorption spectrum of the material for forming the alignment layer. Further, for example, when the wavelength is 313 nm, a high-pressure mercury lamp having a relatively large spectrum of 313 nm can be used as the light source.

-Lovers As shown in FIG. 2, the parallel plates 21 are arranged at equal intervals in the axial direction X of the backup roll 40, and are arranged between the rod-shaped light source 10 and the wire grid polarizer 30. .. By arranging the louver 20, the light from the rod-shaped light source 10 can be made parallel, the spread of the light incident on the wire grid polarizer 30 can be suppressed, and the light can be made directly in front of the backup roll.
Further, in FIG. 2, the parallel plates 21 are arranged at an angle orthogonal to the axial direction X of the backup roll, but the parallel plates 21 may be arranged not only orthogonally but also in parallel in an oblique direction. The pitch and angle of the parallel plate 21 can be adjusted by an interlocking mechanism (not shown).

Note that FIG. 2 shows a case where the louver 20 is composed of parallel plates arranged in the axial direction of the backup roll 40, but the configuration of the louver 20 is not limited to this. It may be composed of a plurality of tubular parts having a polygonal or circular cross section, and the central axis of the cylinder may be arranged in a direction perpendicular to the central axis of the backup roll, and the surface constituting the cylinder has an antireflection film. You may.

Further, it is preferable that the louver 20 is arranged as close as possible to the rod-shaped light source 10 so as not to leak light from the louver. In order to suppress light leakage, the louver and the rod-shaped light source 10 may be brought into contact with each other, or the gap may be shielded by another member.
The same applies to the gap between the louver 20 and the wire grid polarizer 30.

As the material of the louver 20, a heat-resistant material such as stainless steel or aluminum can be used.
The surface of the louver 20 may be smoothed to improve the reflectance in order to increase the irradiation efficiency of the irradiation light. Further, the louver 20 may be provided with irregularities on the surface or covered with a non-reflective film to reduce the reflectance in order to enhance the straightness of the irradiation light. When reducing the reflectance of the surface of the louver 20, it is preferable that a light absorbing member is provided on the surface of the parallel plate 21 of the louver 20.

-Wire Grid Polarizer As shown in FIGS. 2 and 3, the wire grid polarizing element 30 includes a plurality of wire grid polarizing elements 32 held in a frame 31.
In each wire grid polarizing element 32, a wire grid 34 composed of a plurality of linear electric conductors is arranged on the substrate 33. As shown in FIG. 3, the arrangement angle θ of the wire grid 34 preferably satisfies 0 ° <θ <90 ° with respect to the axial direction X of the backup roll.
The wire grid polarizing element 32 reflects the polarized (polarized) component parallel to the longitudinal direction of the wire grid 34, and passes the polarized (polarized) component orthogonal to the wire grid 34. The direction of passing through the orthogonal polarization components is called the transmission axis.
Examples of the electric conductor include metal wires such as chromium and aluminum.

-Irradiation angle of polarized ultraviolet rays by the photoaligner Next, the irradiation angle of polarized ultraviolet rays on the backup roll will be described with reference to FIG.
As shown in FIG. 4, in the plane perpendicular to the axis center O of the backup roll 40, the line passing through the axis center O of the backup roll 40 and perpendicular to the substrate surface 38 of the wire grid polarizer 30 is defined as the reference line L1. The angle formed by the line L1 and the line L2 connecting the axial center O of the backup roll 40 and the upstream end M in the transport direction of the polarized light irradiation region A on the continuous film support 50 is θ1, and the reference line L1 and the backup When the angle formed by the line L3 connecting the axial center O of the roll 40 and the downstream end N of the polarization ultraviolet irradiation region A in the transport direction on the continuous film support 50 is θ2, | θ1-θ2 | <10 ° It is preferable to satisfy.
More preferably, | θ1-θ2 | <7 °, and even more preferably, | θ1-θ2 | = 0 °.
By setting | θ1-θ2 | <10 °, it is possible to irradiate the irradiation curved surface of the backup roll 40 with polarized ultraviolet rays from the front, and it is possible to reduce the variation in the orientation axis of the liquid crystal compound.

By irradiating the first coating film with polarized ultraviolet rays as described above, a photoreaction is generated in the material for forming the alignment layer, and as a result, an alignment layer having an orientation regulating force for the liquid crystal compound is formed. ..

[Second coating film forming step]
The method for producing a retardation film includes a second coating film forming step of applying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer and drying to form a second coating film after the alignment layer forming step. ..
As a specific embodiment, for example, a liquid crystal layer forming material containing a liquid crystal compound may be applied and dried on the alignment layer to form a second coating film.
An example of the second coating film forming step will be described with reference to FIG.
As shown in FIG. 1, when the irradiation of the first coating film on the backup roll with polarized ultraviolet rays is completed, the liquid crystal layer forming material containing the liquid crystal compound is subsequently applied by the coating means 3 of the liquid crystal layer forming material. The coating is performed, and then the material for forming the liquid crystal layer is dried in the drying region by the drying means 4. In this way, a second coating film is formed on the alignment layer of the continuous film support.

-Material for forming a liquid crystal layer-
The liquid crystal layer forming material contains a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound, and may further contain other known components such as a chiral agent, an orientation control agent, a polymerization initiator, and an orientation auxiliary.

-Stick-shaped liquid crystal compounds Examples of rod-shaped liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, and alkoxy-substituted products. Phenylpyrimidines, phenyldioxans, trans and alkenylcyclohexylbenzonitriles are preferably used.
Not only low molecular weight liquid crystal molecules as described above, but also high molecular weight liquid crystal molecules can be used.

It is more preferable to fix the orientation of the rod-shaped liquid crystal compound by polymerization, and therefore it is preferable to use a rod-shaped liquid crystal compound having a polymerizable group.
Examples of the polymerizable rod-shaped liquid crystal compound include Makromol. Chem. , 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, 5,622,648, 5770107, International Publication 95/22586, 95 / No. 24455, No. 97/00600, No. 98/23580, No. 98/52905, Japanese Patent Application Laid-Open No. 1-272551, No. 6-16616, No. 7-110469, No. 11-8801, And the compounds described in Japanese Patent Application No. 2001-64627.
Further, as the rod-shaped liquid crystal compound, for example, those described in JP-A No. 11-513019, JP-A-2007-279688, etc. can be preferably used.

-Disc-shaped liquid crystal compound As the disk-shaped liquid crystal compound, for example, those described in JP-A-2007-108732, JP-A-2010-2404038 and the like can be preferably used.

-Applying and drying-
Since the same method as the coating and drying in the first coating film forming step can be used for the coating and drying of the liquid crystal layer forming material, detailed description thereof will be omitted here.

[Liquid crystal layer forming process]
The method for producing a retardation film includes, after the second coating film forming step, a liquid crystal layer forming step of aligning the liquid crystal compound in the second coating film and fixing the orientation to form the liquid crystal layer.
An example of the liquid crystal layer forming step will be described with reference to FIG.
As shown in FIG. 1, after a second coating film is formed on the alignment layer of the continuous film support 50, the second coating film is irradiated with ultraviolet rays by the ultraviolet irradiation means 5. By irradiating with this ultraviolet ray, the orientation of the liquid crystal compound in the second coating film is fixed to form a liquid crystal layer.

-Orientation of liquid crystal compounds-
Before fixing the orientation of the liquid crystal compound, it is preferable to perform the orientation treatment of the liquid crystal compound in the second coating film.
The orientation treatment can be carried out by drying at room temperature or the like and then controlling the temperature by heating.
In the case of a liquid crystal compound having thermotropic properties, the liquid crystal formed by the orientation treatment can generally be transferred by a change in temperature or pressure. Further, in the case of a liquid crystal compound having a lyotropic property, it can be transferred by a composition ratio such as a solvent amount.

When the rod-shaped liquid crystal compound expresses the smectic phase, the temperature range in which the nematic phase is expressed is usually higher than the temperature range in which the rod-shaped liquid crystal compound expresses the smectic phase. Therefore, the rod-shaped liquid crystal compound is heated to the temperature range in which the rod-shaped liquid crystal compound expresses the nematic phase, and then the heating temperature is lowered to the temperature range in which the rod-shaped liquid crystal compound expresses the smectic phase, whereby the rod-shaped liquid crystal compound is brought into the nematic phase. Can be transferred to the smectic phase. By forming the smectic phase in this way, a liquid crystal in which the liquid crystal compounds are oriented with high order can be obtained.

In the temperature range where the rod-shaped liquid crystal compound expresses the nematic phase, it is necessary to heat for a certain period of time until the rod-shaped 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 in which the rod-shaped liquid crystal compound expresses the smectic phase, it is necessary to heat for a certain period of time until the rod-shaped liquid crystal compound expresses the 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 orientation of the liquid crystal compound may be performed by drying in the second coating film forming step described above. That is, in the drying in the second coating film forming step, both the drying of the liquid crystal layer forming material coated on the alignment layer and the orientation of the liquid crystal compound may be performed.
Of course, the orientation of the liquid crystal compound may be performed separately from the drying in the second coating film forming step described above.

-Fixing the orientation of liquid crystal compounds-
The orientation of the liquid crystal compound in the second coating film is fixed.
The orientation of the liquid crystal compound can be fixed by thermal polymerization or polymerization by active energy rays, and can be carried out by appropriately selecting a polymerizable group or a polymerization initiator of the liquid crystal compound suitable for the polymerization.
Considering the production suitability and the like, the polymerization reaction by the ultraviolet rays irradiated from the ultraviolet irradiation means 5 as shown in FIG. 1 can be preferably used.
When a polymerizable liquid crystal compound is used, if the irradiation amount of ultraviolet rays is small, the unpolymerized liquid crystal compound remains, which causes temperature change of optical characteristics, deterioration with time, and the like. Therefore, it is preferable to determine the irradiation conditions so that the proportion of the remaining unpolymerized liquid crystal compound is 5% by mass or less.
The irradiation conditions, the formulation of the liquid crystal layer forming material, and depending on the thickness of the second coating film, the amount of ultraviolet irradiation is ^{preferably 50mJ / cm 2 ~1000mJ / cm 2} , 100mJ / cm 2 ~500mJ / Cm ² is more preferable.

Examples of the light source used for the ultraviolet irradiation means 5 include lamps such as tungsten lamps, halogen lamps, xenon lamps, xenon flash lamps, mercury lamps, mercury xenon lamps, and carbon arc lamps, and various lasers (eg, semiconductor lasers, helium neon). Examples thereof include a laser, an argon ion laser, a helium cadmium laser, a YAG (Ytrium Aluminum Garnet) laser), a light emitting diode, and a cathode wire tube.

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

[Adhesion removal process]
The method for producing the retardation film can include a step of removing deposits on the surface of the backup roll (in the present specification, it may be referred to as a deposit removing step).
By including the deposit removing step, it is possible to remove rust and dirt on the surface of the backup roll caused by continuous use of the backup roll, and it is possible to continuously suppress the variation in the irradiation amount of the reflected light to the alignment layer to a low level. it can. As a result, the uniformity of the orientation axis can be maintained for a long period of time.

The deposit removing step will be described in detail below.
The deposit removing step is not particularly limited as long as it can remove rust and dirt on the surface of the backup roll, but it can be performed by using, for example, a deposit removing device.

Examples of the deposit removing device include a deposit removing roll, a blower, a wiper, a dipping washer, and the like. Of these, a deposit removing roll and a wiper are preferable.

The deposit removing step is not particularly limited as long as it can remove rust and dirt on the surface of the backup roll. For example, a roll coated with a substance for removing deposits on the surface of the backup roll (the present specification). A method of removing deposits on the surface of the backup roll by arranging the deposit removal roll (referred to as) in contact with the surface of the backup roll and rotating it at the same speed in the direction opposite to the rotation of the backup roll. Can be mentioned.
Examples of the deposit removing roll include mimosa roll (manufactured by Miyagawa Roller Co., Ltd.).
The substance to be applied to the surface of the deposit removing roll is not particularly limited as long as it can remove the deposits on the surface of the backup roll, and examples thereof include adhesive substances such as silicon rubber, fluororubber and urethane rubber. Be done. Of these, urethane rubber is preferable.

The blower may be any device that can blow air to the extent that dust and dirt on the roll surface are blown off, and examples thereof include SJF-300L-3 (manufactured by Suiden Co., Ltd.).

Examples of the wiping device include a device that wipes dust and dirt by bringing a cloth or the like into contact with the roll surface, and examples thereof include a cleaner cot (manufactured by Meitec Corporation) and Bencot Super NT (manufactured by Asahi Kasei Corporation).

Examples of the immersion washer include a device in which a cleaning solution is contained in a container and a rotating roll can be brought into contact with or immersed in the cleaning solution to remove deposits. For example, Dip Washer DW (Nisshin Seiki Co., Ltd.) (Made by company), etc.

[Phase difference film manufacturing equipment]
In the retardation film manufacturing apparatus of the present disclosure, the first coating means for applying the alignment layer forming material to the continuously conveyed continuous film support and the first coating means for drying the alignment layer forming material after coating are dried. The first drying means for forming the coating film, the backup roll having a surface reflectance deviation of 1 percentage point or less, and the first coating film being irradiated with ultraviolet rays with the continuous film support wrapped around the backup roll. Then, an alignment layer forming means for forming an alignment layer having an orientation regulating force on the liquid crystal compound, a second coating means for applying a liquid crystal layer forming material containing the liquid crystal compound on the alignment layer, and a post-coating method. A second drying means for drying the liquid crystal layer forming material to form a second coating film, and a liquid crystal layer forming means for orienting the dried liquid crystal compound and fixing the orientation to form the liquid crystal layer. Be prepared.

[First coating means]
The first coating means is a means for coating a material for forming an alignment layer on a continuous film support that is continuously conveyed.
The continuous film support and the material for forming the alignment layer are the same as those in the first coating film forming step described above, and the preferable range and the like are also the same. As the coating means, the above-mentioned coating device can be used.

[First drying means]
The first drying means is a means for forming a first coating film by drying the material for forming an alignment layer after coating. As the drying means, the above-mentioned drying device can be used.

[Orientation layer forming means]
The alignment layer forming means is a means for forming an alignment layer having an orientation regulating force for a liquid crystal compound by irradiating the first coating film with ultraviolet rays in a state where a continuous film support is wound around a backup roll.

Irradiation of ultraviolet rays (UV) can be performed using a light source capable of irradiating ultraviolet rays.
As the light source, a light source similar to the rod-shaped light source described above can be used. As a specific example, the above-mentioned photoalignment apparatus can be used. As a result, it is possible to form an alignment layer having an orientation regulating force for the liquid crystal compound.

[Second coating means]
The second coating means coats a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer.
The liquid crystal layer forming material, the rod-shaped liquid crystal compound, and the disk-shaped liquid crystal compound are the same as those in the above-mentioned second coating film forming step, and the preferable range is also the same. As the coating means, the above-mentioned coating device can be used.

[Second drying means]
The second drying means dries the liquid crystal layer forming material after coating to form a second coating film. As the drying means, the above-mentioned drying device can be used.

[Liquid crystal layer forming means]
The liquid crystal layer forming means is a means for orienting a liquid crystal compound after drying and fixing the orientation to form a liquid crystal layer.

The liquid crystal layer forming means can include means for drying or heating the liquid crystal compound at room temperature or the like. Thereby, the orientation treatment of the liquid crystal compound can be performed. As the means for drying or heating, the above-mentioned coating device or the above-mentioned drying device can be used.

The liquid crystal layer forming means can include an ultraviolet irradiation means. As a result, the orientation of the liquid crystal compound can be fixed to form the liquid crystal layer.
As the light source in the ultraviolet irradiation means, the light source used in the ultraviolet irradiation means 5 in the liquid crystal layer forming step described above can be used.

Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to the following Examples as long as the gist of the present disclosure is not exceeded. Unless otherwise specified, "parts" are based on mass.

[Example 1]
First, an apparatus having the same configuration as in FIG. 1 was prepared, and the retardation film 1 was manufactured using this apparatus as shown below.
(Formation of first coating film)
A material for forming an orientation layer having the following composition was applied to a continuous film support (cellulose triacetate film TJ40, manufactured by Fujifilm Corporation, total width: 1.3 m, length 2000 m, thickness 40 μm) with a wire bar. Then, it was dried with warm air at 60 ° C. for 60 seconds and further with warm air at 100 ° C. for 120 seconds to form a first coating film having a dry film thickness of 0.5 μm (first coating film forming step).

-Composition of materials for forming an orientation layer-
Material for photoalignment P-1 1.0 part Butoxyethanol 33 parts Propylene glycol monomethyl ether 33 parts Water 33 parts

(Irradiation of polarized ultraviolet rays)
Next, the continuous film support on which the first coating film was formed was brought into contact with the surface opposite to the surface coated with the alignment layer forming material, and the backup roll 1 (diameter 600 mm, material = stainless steel (SUS304)) was formed. The surface is treated with black alumite, Ra = 0.1 μm, surface color: metallic luster, surface reflectance deviation: 0.5 percentage points, ultraviolet absorption rate: 99%) wrapped around (see Fig. 2), under the atmosphere. Ultraviolet rays (wavelength 313 nm) were irradiated using an air-cooled metal halide lamp (Igraphics Co., Ltd.). At this time, the arrangement angle θ of the wire grid in the wire grid polarizer (ProFlux UVT-300A manufactured by Moxtek) is set to 45 °, and the orientation layer is irradiated with polarized ultraviolet rays with | θ1-θ2 | = 0 °. Was formed (alignment layer forming step).
At this time, the illuminance of ultraviolet rays was 10 mW / cm ² in the UV (ultra-violet) -A region (integration of wavelengths of 320 nm to 380 nm), and the irradiation amount was 10 mJ / cm ² in the UV-A region.

(Formation of a second coating film and formation of a liquid crystal layer)
Subsequently, a material for forming a liquid crystal layer having the following composition was prepared.

-Composition of material for forming liquid crystal layer-
Reverse wavelength dispersion liquid crystal compound R-3 100 parts Photopolymerization initiator 3.0 parts (Irgacure 819, BASF)
Fluorine-containing compound A 0.8 part Crosslinkable polymer O-2 0.3 part Chloroform 588 part

A liquid crystal layer forming material was applied onto the alignment layer using a bar coater.
By heating and drying at a film surface temperature of 100 ° C. for 60 seconds, a second coating film having a dry film thickness of 200 nm is formed (second coating film forming step), cooled to 70 ° C., and then in air. An air-cooled metal halide lamp (Igraphics Co., Ltd.) was used to irradiate ultraviolet rays of 1000 mJ / cm ² to fix the orientation state and form a liquid crystal layer (liquid crystal layer forming step).
As described above, the retardation film 1 was obtained.

(Adhesion removal process)
The deposits adhering to the surface of the backup roll were removed by the following method.

-Remove of deposits with a blower-
First, a blower (SJF-300L-3 (manufactured by Suiden Co., Ltd.)) was used to blow air onto the surface of the backup roll to blow off dust and dirt and remove deposits on the surface of the backup roll.
-Remove of deposits with a wiper-
Next, every time one roll of the retardation film was produced, the deposits were removed by a wiping device once.
Specifically, after applying the solvent methyl ethyl ketone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to the surface of the backup roll by spraying, the wiping is installed downstream of the winding region of the continuous film support in the rotation direction of the backup roll. This was done by wiping off deposits and solvents using a vessel (cellulose cloth (Bencot Super NT, manufactured by Asahi Kasei Corporation)).

-Remove of deposits with a dipping washer-
Then, as a dipping washer, a dip washer DW (manufactured by Nissin Seiki Co., Ltd.) was used to immerse the backup roll in the cleaning liquid to remove deposits on the surface of the backup roll.

-Removal of deposits with a deposit removal roll-
Finally, as shown in FIG. 2, an adhesive deposit removing roll (Mimosa roll, manufactured by Miyagawa Roller Co., Ltd.) 41 is installed so as to come into contact with the backup roll 40, and the direction in which the backup roll 40 rotates is opposite to that of the rotation. The deposits on the surface of the backup roll were removed by rotating the deposit removing roll 41 in the direction of.

[Example 2]
A retardation film 2 was obtained in the same manner as in Example 1 except that the deposits were not removed by the wiper, the deposit removing roll, the blower, and the immersion washer.

[Example 3]
The backup roll 1 is the same as that of the first embodiment except that the backup roll 2 (diameter 600 mm, material stainless steel, surface: mirror surface, Ra = 0.05 μm, surface reflectance deviation: 1 percentage point, ultraviolet absorption rate: 60%). In the same manner, a retardation film 3 was obtained.

[Example 4]
A retardation film 4 was obtained in the same manner as in Example 3 except that the deposits were not removed by the wiper, the deposit removing roll, the blower, and the immersion washer.

[Example 5]
Phase difference in the same manner as in Example 3 except that the deposit removal step was performed only by removing the deposits by the immersion washer and not by the wiper, the deposit removal roll and the blower. Film 5 was obtained.

[Example 6]
In the same manner as in Example 3, the phase difference is the same as in Example 3, except that as the deposit removing step, only the deposits are removed by the deposit removing roll, and the deposits are not removed by the wiper, the blower, and the immersion washer. Film 6 was obtained.

[Example 7]
In the same manner as in Example 3, the phase difference is the same as in Example 3 except that the deposit removal step is performed only by removing the deposits by the blower and not by the deposit removing roll, the wiper and the immersion washer. Film 11 was obtained.

[Example 8]
In the same manner as in Example 3, the phase difference was the same as in Example 3 except that the deposit removal step was performed only by removing the deposits with a wiper and not removing the deposits with a deposit removing roll, a blower, and a dipping washer. Film 12 was obtained.

[Comparative Example 1]
Change the backup roll 1 to the backup roll 3 (diameter 600 mm, material stainless steel, surface color: metal color (silver), surface reflectance deviation: 2 percentage points, ultraviolet absorption rate: 60%), wiper, deposits A retardation film 7 was obtained in the same manner as in Example 1 except that the deposits were not removed by the removing roll, the blower, and the immersion washer.

<Evaluation>
(Evaluation of uniformity of orientation axis)
A film was sandwiched between Shakasten (cross Nicol: an arrangement in which the transmission axes of the two polarizing plates are orthogonal to each other), and the film was rotated in the plane to search for the quenching position. If the axis of orientation is uniform, the entire in-plane quenches at an angle. On the other hand, if the orientation axis is deviated, the quenching angle is different in the plane.
The uniformity of the alignment axis is evaluated immediately after the start of production (within a range of 1 m from the end of production of the manufactured retardation film) and immediately before the end of production (1 m from the end of production of the manufactured retardation film). Orientation layer). The evaluation criteria are as follows.
Immediately before the end of production is immediately before the end of the production process in which 30 consecutive retardation films are produced using a 1000 m roll.
<Evaluation criteria>
A: There is only one quenching angle in the plane.
B: The quenching angle is 2 to 3 in the plane.
C: The quenching angle is 4 to 5 in the plane.
D: The quenching angle is 6 or more in the plane.

(Measurement method of surface reflectance deviation of backup roll)
For the surface reflectance of the backup roll, measurement points are taken at a pitch of 10 mm in the roll width direction of the backup roll at 12 points where the backup roll is divided into 12 in the circumferential direction, and the front reflectance for light having a wavelength of 365 nm at each measurement point is determined. It was measured.
A spectrophotometer (MV-3100, manufactured by JASCO Corporation) was used to measure the surface reflectance of the backup roll.
Here, the wavelength can be appropriately selected according to the absorption spectrum of the material for forming the alignment layer, and may be, for example, 313 nm. At this time, the light source used is a high-pressure mercury lamp having a relatively large spectrum of 313 nm.
The surface reflectance deviation of the backup roll is expressed as the difference (percent point) between the maximum value and the minimum value of the surface reflectance measured as described above. The larger this difference is, the larger the variation in the surface reflectance of the backup roll in the width direction is.
If the difference is 3 percentage points or more, it is not practically preferable.

(Measuring method of absorption rate of backup roll for ultraviolet rays with wavelength of 300 nm to 380 nm)
For the reflectance of the backup roll to ultraviolet rays with a wavelength of 300 nm to 380 nm, first, measurement points are taken at a pitch of 10 mm in the roll width direction of the backup roll at 12 points where the backup roll is divided into 12 in the circumferential direction, and the wavelength at each measurement point is 300 nm. The reflectance to ultraviolet rays of ~ 380 nm was measured with a spectrophotometer (MV-3100 manufactured by JASCO Corporation), the average value was calculated by averaging each measured value, and the average value of the calculated reflectance was calculated from 1. It is the value obtained by subtracting.

(Measurement method of surface roughness (Ra) of backup roll)
The surface roughness (Ra) was measured using a surface roughness measuring instrument (SJ-310, manufactured by Mitutoyo Co., Ltd.) by a method conforming to Japanese Industrial Standards (JIS) B0601 (2001).

As shown in Table 1, in Examples 1 to 6 in which the surface reflectance deviation of the backup roll was 1.0 percentage point or less, the uniformity of the orientation axis immediately after the start of production and immediately before the end of production was good.
Among them, in Examples 1 and 2 in which the surface reflectance deviation of the backup roll was 0.5 percentage point or less, the uniformity of the orientation axis immediately after the start of production and immediately before the end of production was particularly good.

The disclosure of Japanese Patent Application No. 2018-024447 filed on February 14, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims (8)

A step of applying a material for forming an alignment layer to a continuous film support that is continuously conveyed and drying it to form a first coating film.
A continuous film support is wound around a backup roll having an in-plane deviation of the front reflectance of the surface of 1 percentage point or less, and the first coating film is irradiated with polarized ultraviolet rays to regulate the orientation of the liquid crystal compound. The process of forming an oriented layer with force and
A step of applying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer and drying it to form a second coating film.
A step of orienting the liquid crystal compound in the second coating film and fixing the orientation to form a liquid crystal layer.
A method for producing a retardation film having. The method for producing a retardation film according to claim 1, wherein the surface of the backup roll is a mirror surface. The method for producing a retardation film according to claim 1 or 2, which comprises a step of removing deposits on the surface of the backup roll. The method for producing a retardation film according to claim 3, wherein the removal is performed using a deposit removing device. The method for producing a retardation film according to claim 4, wherein the deposit removing device is a deposit removing roll, a blower, a wiper, or a dipping washer. The method for producing a retardation film according to any one of claims 1 to 5, wherein the backup roll has an absorption rate of 60% to 99.95% for ultraviolet rays having a wavelength of 300 nm to 380 nm. The method for producing a retardation film according to any one of claims 1 to 6, wherein the material of the backup roll is stainless steel, or the surface of the backup roll is black. A first coating means for coating a material for forming an alignment layer on a continuous film support that is continuously conveyed, and
A first drying means for forming a first coating film by drying the material for forming an alignment layer after coating, and
A backup roll with an in-plane deviation of surface front reflectance of 1 percentage point or less,
An alignment layer forming means for forming an alignment layer having an orientation regulating force for a liquid crystal compound by irradiating the first coating film with ultraviolet rays in a state where a continuous film support is wound around the backup roll.
A second coating means for coating a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer,
A second drying means for forming a second coating film by drying the material for forming a liquid crystal layer after coating, and
A liquid crystal layer forming means for orienting a dried liquid crystal compound and fixing the orientation to form a liquid crystal layer.
A device for producing a retardation film.