WO2018092657A1 - Optical film, polarizing plate protection film, polarizing plate including these films, and display device including these films - Google Patents

Abstract

The present invention provides a means which enables the achievement of good crack resistance, and durability and adhesiveness under a high-temperature and high-humidity environment of a cyclic polyolefin film for optics application. The present invention relates to an optical film comprising a cyclic polyolefin film and a stress relaxation layer disposed on the cyclic polyolefin film, wherein the stress relaxation film contains Si atoms, O atoms and C atoms, and an average value X_AVE in a thickness direction of a ratio X(%) of a C-C bond to the sum total of peak intensities resulting from C-C, C-SiO, C-O, C=O and C(=O)-O bonds at each measurement position found from a depth profile of a C1s spectral region measured by X-ray photoelectron spectroscopy of the stress relaxation layer is 1-40% inclusive.

Description

Optical film, polarizing plate protective film, polarizing plate including these, and display device including these

The present invention relates to an optical film, a polarizing plate protective film, a polarizing plate including these, and a display device including these.

In recent years, flexible resins that have achieved high transparency, high functionality, and light weight, such as polarizing film protective films and retardation films for liquid crystal display devices that are display devices and organic electroluminescence display devices. There is a great demand for film. Among resin films, the cyclic polyolefin film is excellent in transparency, heat resistance, electrical characteristics, and the like, and therefore, application as an optical film is being studied.

However, it is known that the cyclic polyolefin film is liable to generate minute cracks at the end during punching or cutting. Such defects such as minute cracks at the ends and cracks caused by the cracks can cause display failure when a cyclic polyolefin film is used in a display device, for example. Thus, as a cyclic polyolefin film for optical use, a technique for improving the film strength has been studied.

JP-A-2004-67984 discloses an optical film obtained from a resin composition containing a norbornene resin and a cycloolefin resin having a specific structure. And the same literature discloses that transparency, moisture permeability, and strength can be improved by the optical film having this configuration.

Japanese Patent Application Laid-Open No. 2008-274136 discloses a cycloolefin-based resin film having an impact strength of 1000 J / m to 30000 J / m, and by using the film as an optical film, It is disclosed that the occurrence of cracks can be suppressed.

However, the technique disclosed in Japanese Patent Application Laid-Open No. 2004-67984 cannot sufficiently suppress crack generation at the time of film punching or cutting, and crack expansion over time in a high-temperature and high-humidity environment. There is a problem that is not sufficiently suppressed. In addition, the technique disclosed in Japanese Patent Application Laid-Open No. 2008-274136 has a problem that display failure is not sufficiently suppressed because generation or expansion of cracks over time in a high temperature and high humidity environment cannot be sufficiently suppressed. Furthermore, both of these techniques have a problem that when the cyclic polyolefin film and another member such as a polarizer are bonded, delamination occurs between the cyclic polyolefin film and the other member during bending.

Therefore, an object of the present invention is to provide a means capable of achieving both good crack resistance, durability in a high-temperature and high-humidity environment, and adhesiveness for a cyclic polyolefin film for optical use.

The above-mentioned problem of the present invention is solved by the following means.

A cyclic polyolefin film;
A stress relieving layer disposed on the cyclic polyolefin film,
The stress relaxation layer contains silicon atoms (Si), oxygen atoms (O) and carbon atoms (C), and
C—C, C—SiO, C—O, C═O and C (═O) — at each measurement position, obtained from the depth profile of the C1s spectral region measured by X-ray photoelectron spectroscopy of the stress relaxation layer. The average value X _{AVE in the} thickness direction of the ratio X (%) of the peak intensity derived from the C—C bond to the sum of the peak intensity derived from each bond of O is 1% or more and 40% or less,
Optical film.

It is a cross-sectional schematic diagram which shows an example of the optical film which concerns on this invention. It is a schematic diagram which shows an example of the manufacturing apparatus used for formation of the stress relaxation layer which concerns on this invention.

One embodiment of the present invention includes a cyclic polyolefin film, and a stress relaxation layer disposed on the cyclic polyolefin film. The stress relaxation layer includes silicon atoms (Si), oxygen atoms (O), and carbon atoms ( C), and C—C, C—SiO, C—O, C = at each measurement position obtained from the depth profile of the C1s spectral region measured by X-ray photoelectron spectroscopy of the stress relaxation layer. The average value X _{AVE in the} thickness direction of the ratio X (%) of the peak intensity derived from the C—C bond to the total peak intensity derived from each bond of O and C (═O) —O is 1% or more and 40 % Is an optical film. According to one aspect of the present invention, there is provided a means capable of achieving both good crack resistance, durability in a high-temperature and high-humidity environment, and adhesiveness for a cyclic polyolefin film for optical applications.

The present inventors presume the mechanism by which the problem is solved by the above configuration as follows. The optical film which concerns on one form of this invention has a stress relaxation layer containing a silicon atom (Si), an oxygen atom (O), and a carbon atom (C) on a cyclic polyolefin film. The stress relaxation layer is selected from the group consisting of C—C bonds, C—SiO, C—O, C═O, and C (═O) —O as carbon-related bonds in the composition. Among these, a C—C bond, which is a soft bond, is included at a predetermined ratio. At this time, the stress relaxation layer relieves stress applied from the outside at the time of punching or cutting, or stress generated upon self-deformation when the optical film is placed in a high temperature and high humidity environment. Furthermore, when placed in a high temperature and high humidity environment with the optical film and another member bonded, the stress applied from the outside when the other member is deformed over time, or the self deformation Relieve the generated stress. As a result, generation of cracks or expansion of cracks is suppressed, and crack resistance and durability in a high temperature and high humidity environment are improved. Further, at this time, when deformation such as bending is performed in a state where the optical film and the other member are bonded, the stress concentrated on the bonding interface between the optical film and the other member is relieved, and the optical film Fracture in the region near the interface is suppressed. Furthermore, depending on the type of the other member, the interaction due to the polarity between the optical film and the other member is enhanced. As a result, the adhesiveness is improved. Note that the above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

Hereinafter, preferred embodiments of the present invention will be described. In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, the operation and physical properties are measured under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50% RH.

In addition, the dimensional ratio of the drawings is exaggerated for convenience of explanation and may be different from the actual ratio.

FIG. 1 is a schematic cross-sectional view showing an example of an optical film according to the present invention. Here, 1 is an optical film, 2 is a cyclic polyolefin film, and 3 is a stress relaxation layer. The optical film according to the present invention is not limited to this structure.

Hereinafter, each component of the optical film will be described in detail.

<Stress relaxation layer>
The optical film which concerns on one form of this invention has a stress relaxation layer. The stress relaxation layer is a layer containing silicon atoms (Si), oxygen atoms (O), and carbon atoms (C), and is obtained from a depth profile in the C1s spectral region measured by X-ray photoelectron spectroscopy. Ratio of peak intensity derived from C—C bond to total sum of peak intensity derived from each bond of C—C, C—SiO, C—O, C═O and C (═O) —O at each measurement position ( In this specification, it is a layer in which the average value _{XAVE in the} thickness direction of X (%) (also referred to as CC bond ratio) is 1% or more and 40% or less.

Since the optical film has a cyclic polyolefin film and the stress relaxation layer disposed on the cyclic polyolefin film, it has been difficult to achieve with a cyclic polyolefin film alone, and has good crack resistance, high temperature and high temperature. It is possible to achieve both durability and adhesion in a wet environment.

(Composition of stress relaxation layer)
A layer that does not have any of silicon atoms (Si), oxygen atoms (O), and carbon atoms (C) cannot exhibit the effects of the present invention. A layer having no carbon atom has insufficient crack resistance and durability under a high temperature and high humidity environment. This is because it is considered that a CC bond which is a flexible bond cannot be included and a stress relaxation effect cannot be exhibited. Further, a layer having no silicon atom or oxygen atom has insufficient durability and adhesiveness in a high temperature and high humidity environment. The reason for this is that gases such as water vapor and oxygen easily enter the layer in a high-temperature and high-humidity environment, and the oxidation of the layer-forming material proceeds with water, oxygen, etc., and the layer having a stress relaxation effect and good adhesion This is because it is considered that the composition is not maintained. In addition, the reason why the adhesiveness is insufficient is that, when these atoms are not included, it is considered that the interaction due to the polarity between the optical film and the other member may be weakened.

Note that the stress relaxation layer has silicon atoms (Si), oxygen atoms (O), and carbon atoms (C), as confirmed by the results of wide scan spectrum analysis in element distribution profile measurement by X-ray photoelectron spectroscopy, which will be described later. can do.

When X _AVE is less than 1%, the crack resistance is insufficient. This is because it is considered that the C—C bond, which is a flexible bond, cannot be included in a sufficient amount, and the stress relaxation effect cannot be exhibited. From the viewpoint of further improving the stress relaxation effect and further improving the crack resistance, X _AVE is preferably 2% or more. On the other hand, if _XAVE is more than 40%, the adhesion is insufficient. This is because the content of silicon atoms or oxygen atoms becomes excessive, and gas such as water vapor and oxygen easily enters the layer in a high-temperature and high-humidity environment, and the oxidation of the layer forming material proceeds with water or oxygen. This is because it is considered that the composition of the layer having good adhesiveness is not maintained. Alternatively, the reason is that the layer-forming material has an easily oxidizable composition due to the excessive C—C bond content, and the layer-forming material is oxidized by water, oxygen, etc., and has good adhesion. This is because it is considered that the composition of is not maintained. Or this reason is because it is thought that the interaction by the polarity between an optical film and another member may weaken. X _AVE is preferably 20% or less from the viewpoint of further enhancing the oxidation resistance of the layer or further strengthening the interaction due to the polarity between the optical film and other members and further improving the adhesion. . Accordingly, an example of a preferable _XAVE range according to the present invention is 2% or more and 20% or less, but the present invention is not limited to this.

X (%) and X _AVE (%) can be calculated from the result of a high resolution spectrum (narrow scan analysis) of C1s in the measurement of an element distribution profile by X-ray photoelectron spectroscopy described later.

In the stress relaxation layer according to an embodiment of the present invention, the stress is measured based on the ratio of peak intensities derived from silicon atoms, oxygen atoms, and carbon atoms obtained by X-ray photoelectron spectroscopy at the depth measurement position in each layer thickness direction. [C _AVE ] (at%), which is an average value of the ratio of carbon atoms (also referred to as carbon composition ratio in this specification) [C] (at%) when the total amount of the composition ratio is 100 at%, From the viewpoint of further improving crack resistance, it is preferably 2 at% or more. This is because it is considered that the stress relaxation effect is further improved by including a sufficient amount of the C—C bond, which is a flexible bond. From the same viewpoint, [C _AVE ] (at%) is more preferably 4 at% or more, and further preferably 5 at% or more. [C _AVE ] (at%) is preferably 30 at% or less from the viewpoint of further improving the adhesiveness. The reason for this is that the content of silicon atoms or oxygen atoms is sufficient, and gas such as water vapor and oxygen hardly enters the layer in a high-temperature and high-humidity environment, and the oxidation of the layer-forming material is suppressed by water or oxygen. This is because the composition of the layer having good adhesiveness is considered to be maintained more firmly. Alternatively, this is because the layer forming material has a composition in which oxidation is difficult to occur due to the sufficient content of the C—C bond, and the oxidation of the layer forming material is suppressed by water, oxygen, etc. This is because the composition of the layer having the property is considered to be maintained more firmly. Or this reason is because it is thought that the interaction by the polarity between an optical film and another member may become stronger. From the same viewpoint, [C _AVE ] (at%) is more preferably 24 at% or less.

[C] (at%) and [C _AVE ] (at%) can be calculated from the result of wide scan spectrum analysis in the measurement of an element distribution profile by X-ray photoelectron spectroscopy, which will be described later.

[X-ray photoelectron spectroscopy]
Carbon distribution curve (distance (L) from the outermost surface of the stress relaxation layer in the thickness direction of the stress relaxation layer and the total number of carbon atoms (C), silicon atoms (Si), and oxygen atoms (O) (100 at%) )), A silicon distribution curve (distance L and the ratio of the number of silicon atoms to the total number of atoms of carbon, silicon and oxygen atoms (100 at%)) (Curve showing the relationship with (silicon atom ratio)) and oxygen distribution curve (distance L and the ratio of the number of oxygen atoms to the total number of carbon atoms, silicon atoms and oxygen atoms (100 at%) (oxygen atom ratio) A curve indicating the relationship) using X-ray photoelectron spectroscopy (XPS) measurement and rare gas ion sputtering such as argon Ri, performs sequential surface composition analysis while exposing the internal sample can be made by so-called XPS depth profile measurement.

≪Measurement of element distribution profile≫
The XPS depth profile can be measured, for example, under the following conditions to obtain a carbon distribution curve, a silicon distribution curve, and an oxygen distribution curve with respect to the distance from the surface of the thin film layer in the layer thickness direction.

Etching ion species: Argon (Ar ⁺ ),
Etching rate (SiO ₂ thermal oxide equivalent value): 0.05 nm / sec,
Etching interval (SiO ₂ equivalent value): 2 nm,
X-ray photoelectron spectrometer: manufactured by Thermo Fisher Scientific, model name “VG Theta Probe”
Irradiation X-ray: Single crystal spectroscopy AlKα,
X-ray spot and size: 800 μm × 400 μm oval.

The distribution curve obtained by such XPS depth profile measurement can be created, for example, with the vertical axis as the atomic ratio (at%) of each element and the horizontal axis as the etching time (sputtering time).

The atomic ratio (at%) in each region is a value obtained by etching values in the depth direction by XPS depth profile measurement and averaging values measured at intervals of 2 nm, for example.

As described above, a carbon distribution curve, a silicon distribution curve, and an oxygen distribution curve can be obtained by performing a wide scan spectrum analysis for measuring the entire stress relaxation layer.

From the result of this measurement, the composition converted from the ratio of peak intensities derived from silicon atoms, oxygen atoms and carbon atoms obtained by X-ray photoelectron spectroscopy at each measurement position in the depth direction of the stress relaxation layer. The ratio [C] (at%) of carbon atoms when the total amount of the ratio is 100 at% is calculated. Then, from the value of each [C] (at%) at each measurement position of the depth in the layer thickness direction of the stress relaxation layer, the average value [C _AVE ] (at %) Is further calculated.

≪Analysis of bonding state of carbon atom≫
As for carbon atoms, the bonding state of carbon is analyzed by a high resolution spectrum (narrow scan analysis) of C1s. Specifically, at each measurement position of the depth in the film thickness direction of the stress relaxation layer, (1) CC, (2) C-SiO, Dividing into five bonds such as (3) C—O, (4) C═O, and (5) C (═O) —O, the peak intensity ratio of each spectrum is calculated. When the sum of the peak intensity ratios (1) to (5) above is 100% at each measurement position of the depth in the film thickness direction of the stress relaxation layer, it is derived from the CC bond of (1). The peak intensity ratio X (%) is calculated. Then, X _AVE (%), which is an average value in the film thickness direction of X (%), is further calculated from the value of each X (%) at each measurement position of the depth of the stress relaxation layer in the layer thickness direction. The analysis of the peak intensity can be performed using, for example, data analysis software PeakFit (manufactured by SYSSTAT Software Inc.).

The specific calculation method of [C _AVE ] (at%) and X _AVE using the measurement result of the element distribution profile by X-ray photoelectron spectroscopy is described in the examples. [C _AVE ] (at%) and the control method of X _AVE are described in the stress relaxation layer manufacturing method described later.

Further, in this specification, “the interface with the base material” means “the stress relaxation layer when the composition ratio of oxygen atoms (O) as a part of the composition forming the stress relaxation layer is 30 at% or less”. "The position of the depth from the outermost surface side in the layer thickness direction". The composition ratio of oxygen atoms (O) can be calculated by the X-ray photoelectron spectroscopy described above.

(Thickness of stress relaxation layer)
The layer thickness of the stress relaxation layer according to one embodiment of the present invention (when the stress relaxation layer has a laminated structure of two or more layers on one surface side of the cyclic polyolefin film), the effect of the present invention Is preferably 1 nm or more, more preferably 5 nm or more, from the viewpoint of better expressing the above. In addition, the thickness of the stress relaxation layer according to one embodiment of the present invention is preferably 300 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less from the viewpoint of thinning.

[Method for measuring the thickness of the stress relaxation layer]
The layer thickness of the stress relaxation layer is determined by measuring the depth from the outermost surface to the interface with the base material in the stacking direction of the stress relaxation layer by observing a cross section with a transmission electron microscope (TEM). be able to. In cross-sectional observation with a transmission electron microscope, the layer thickness is arbitrarily measured at 10 locations, and the average value is taken as the layer thickness of the stress relaxation layer.

≪TEM image of cross section in layer thickness direction≫
As a cross-sectional TEM observation, a thin piece is prepared for the observation sample by the following focused ion beam (FIB) processing apparatus, and then the TEM observation is performed. Here, when the sample is continuously irradiated with the electron beam, a contrast difference appears between the portion that is damaged by the electron beam and the portion that is not damaged. Therefore, the thickness of the stress relaxation layer can be measured by the contrast difference.

≪FIB processing≫
Apparatus: SMI2050 manufactured by Seiko Instruments Inc. (SII),
Processing ions: Ga (30 kV),
Sample thickness: 100-200 nm,
≪TEM observation≫
Apparatus: JEM2000FX manufactured by JEOL Ltd. (acceleration voltage: 200 kV).

[Method for producing stress relaxation layer]
The stress relaxation layer according to an embodiment of the present invention is preferably formed by a plasma chemical vapor deposition method (plasma CVD, plasma-enhanced chemical vapor deposition (PECVD), hereinafter also simply referred to as “plasma CVD method”). .

Although it does not specifically limit as a plasma CVD method, Plasma CVD method in the atmospheric pressure or the atmospheric pressure vicinity of international publication 2006/033233, Plasma CVD method using a plasma CVD apparatus with a counter roller electrode, Vacuum plasma CVD method etc. are mentioned. In this specification, the vacuum plasma CVD method refers to a plasma CVD method in which a film is formed at a vacuum degree of 50 Pa or less. The plasma CVD method may be a Penning discharge plasma type plasma CVD method.

In particular, it is preferable to use a source gas containing an organosilicon compound and an oxygen gas by a discharge plasma chemical vapor deposition method (a roll-to-roll method) having a discharge space between rollers to which a magnetic field is applied. As described above, by using the discharge plasma chemical vapor deposition method, it is possible to easily produce a stress relaxation layer in which the carbon atom ratio in each region is controlled within a certain range, and the stress balance in the layer is appropriate. A stress relaxation layer can be produced. Furthermore, it is considered that by using the discharge plasma chemical vapor deposition method, the stress relaxation layer can be densified and the adhesion can be improved. The reason for this is that the composition of the layer having good adhesiveness is such that gas such as water vapor or oxygen hardly enters the layer in a high temperature and high humidity environment, and the oxidation of the layer forming material is suppressed by water, oxygen, etc. This is because is considered to be maintained more firmly.

Hereinafter, a stress relaxation layer according to one embodiment of the present invention is formed by a discharge plasma chemical vapor deposition method having a discharge space between rollers to which a magnetic field is applied, using a source gas containing an organosilicon compound and oxygen gas. A method will be described.

When generating plasma in the plasma CVD method, it is preferable to generate a plasma discharge in a space between a plurality of film forming rollers. A pair of film forming rollers is used, and a cyclic polyolefin is used for each of the pair of film forming rollers. A base material including a film (hereinafter, also simply referred to as a base material. The base material here includes a form in which the base material is treated) is disposed, and plasma is generated by discharging between a pair of film forming rollers. More preferably, it is generated.

Here, the substrate is preferably a cyclic polyolefin film alone, a laminate including the cyclic polyolefin film and an anchor coat layer described later, and more preferably a cyclic polyolefin film alone.

In this way, by using a pair of film forming rollers, placing a base material on the pair of film forming rollers, and discharging between the pair of film forming rollers, one film forming roller It is possible to form a film on the surface part of the base material existing on the other film, and simultaneously form the film on the surface part of the base material present on the other film forming roller, so that a thin film can be produced efficiently. In addition, the film formation rate can be doubled compared to a normal plasma CVD method that does not use a roller.

Further, when discharging between the pair of film forming rollers in this way, it is preferable to reverse the polarities of the pair of film forming rollers alternately. Furthermore, as a film forming gas used in such a plasma CVD method, a gas containing an organosilicon compound and oxygen is preferable.

Hereinafter, the stress relaxation layer forming method according to an embodiment of the present invention will be described in more detail with reference to FIG. FIG. 2 is a schematic diagram illustrating an example of a manufacturing apparatus that can be suitably used for manufacturing the stress relaxation layer according to an embodiment of the present invention. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

2 includes a feed roller 12, transport rollers 13 to 18, film forming rollers 19 and 20, a gas supply pipe 21, a plasma generating power source 22, and film forming rollers 19 and 20. Magnetic field generators 23 and 24 and winding rollers 25 installed inside are provided. Further, in such a manufacturing apparatus 10, at least the film forming rollers 19 and 20, the gas supply pipe 21, the plasma generating power source 22, and the magnetic field generating apparatuses 23 and 24 are provided in the film forming (vacuum) chamber 28. Has been placed. Further, in such a manufacturing apparatus 10, the film forming chamber 28 is connected to a vacuum pump (not shown), and the pressure in the film forming chamber 28 can be appropriately adjusted by such a vacuum pump.

The delivery roller 12 and the transport roller 13 are disposed in the transport system chamber 27, and the winding roller 25 and the transport roller 18 are disposed in the transport system chamber 29. The transfer system chambers 27 and 29 and the film forming chamber 28 are connected via connecting portions 30 and 31, respectively. For example, the film forming chamber 28 and the transfer system chambers 27 and 29 may be physically separated by providing a vacuum gate valve in the connecting portions 30 and 31. By using the vacuum gate valve, for example, only the film forming chamber 28 can be a vacuum system, and the transfer system chambers 27 and 29 can be in the atmosphere. Further, by physically separating the film forming chamber 28 and the transfer system chambers 27 and 29, it is possible to suppress the transfer system chambers 27 and 29 from being contaminated by particles generated in the film forming chamber 28. .

In such a manufacturing apparatus, each film-forming roller 19 and 20 is a power source for plasma generation so that the pair of film-forming rollers (film-forming rollers 19 and 20) can function as a pair of counter electrodes. 22 is connected. Therefore, in such a manufacturing apparatus 10, it is possible to discharge to the space between the film forming roller 19 and the film forming roller 20 by supplying power from the plasma generating power source 22. Plasma can be generated in the space between the film roller 19 and the film formation roller 20. In addition, when using the film-forming roller 19 and the film-forming roller 20 as electrodes as described above, the material and design may be changed as appropriate so that the film-forming roller 19 and the film-forming roller 20 can also be used as electrodes.

Further, in such a manufacturing apparatus 10, it is preferable that the pair of film forming rollers (film forming rollers 19 and 20) be arranged so that their central axes are substantially parallel on the same plane. Thus, by arranging a pair of film forming rollers (film forming rollers 19 and 20), the film forming rate can be doubled as compared with a normal plasma CVD method that does not use a roller.

According to such a manufacturing apparatus 10, the stress relaxation layer 3 can be formed on the surface of the substrate 2 by the CVD method, and the stress relaxation layer is formed on the surface of the substrate 2 on the film forming roller 19. While depositing the material (hereinafter also referred to as stress relaxation layer component), the stress relaxation layer component can be deposited on the surface of the substrate 2 also on the film forming roller 20. The stress relaxation layer can be formed efficiently.

In the film forming rollers 19 and 20, magnetic field generators 23 and 24 fixed so as not to rotate even when the film forming rollers 19 and 20 rotate are provided, respectively.

The magnetic field generators 23 and 24 provided in the film forming rollers 19 and 20 are respectively a magnetic field generator 23 provided in one film forming roller 19 and a magnetic field generator 24 provided in the other film forming roller 20. It is preferable to arrange the magnetic poles so that the magnetic field lines do not cross between each other and the magnetic field generators 23 and 24 form a substantially closed magnetic circuit. By providing such magnetic field generators 23 and 24, it is possible to promote the formation of a magnetic field in which magnetic lines of force swell in the vicinity of the opposing surfaces of the film forming rollers 19 and 20, and the plasma is converged on the bulging portion. Since it becomes easy, it is excellent at the point which can improve the film-forming efficiency.

The magnetic field generators 23 and 24 provided on the film forming rollers 19 and 20 respectively have racetrack-shaped magnetic poles that are long in the roller axis direction, and one magnetic field generator 23 and the other magnetic field generator 24 are It is preferable to arrange the magnetic poles so that the opposing magnetic poles have the same polarity. By providing such magnetic field generators 23 and 24, each of the magnetic field generators 23 and 24 is opposed to the space along the length direction of the roller shaft without straddling the magnetic field generator on the roller side where the magnetic lines of force oppose each other. A racetrack-like magnetic field can be easily formed in the vicinity of the roller surface facing the (discharge region), and the plasma can be focused on the magnetic field, so that a wide base wound around the roller width direction can be obtained. The material 2 is excellent in that the stress relaxation layer 3 that is a vapor deposition film can be efficiently formed.

The tension on the substrate 2 in each of the film forming rollers 19 and 20 may all be the same, but only the tension in the film forming roller 19 or the film forming roller 20 may be increased. By increasing the tension of the film forming rollers 19 and 20 to the base material 2, the adhesion between the base material 2 and the film forming rollers 19 and 20 is improved, heat exchange is efficiently performed, and film uniformity is improved. There is an advantage that heat wrinkles are also suppressed.

As the film forming rollers 19 and 20, known rollers can be used as appropriate. As such film forming rollers 19 and 20, it is preferable to use ones having the same diameter from the viewpoint of forming a thin film more efficiently. Further, the diameter of the film forming rollers 19 and 20 is preferably in the range of 300 to 1000 mmφ, particularly in the range of 300 to 700 mmφ, from the viewpoint of discharge conditions, chamber space, and the like. If the diameter of the film forming roller is 300 mmφ or more, the plasma discharge space will not be reduced, so that the productivity will not be deteriorated and it is possible to avoid applying the total amount of heat of the plasma discharge to the substrate 2 in a short time. It is preferable because damage to the material 2 can be reduced. On the other hand, if the diameter of the film forming roller is 1000 mmφ or less, it is preferable because practicality can be maintained in terms of apparatus design including uniformity of plasma discharge space. Each film-forming roller 19 and 20 may be provided with a nip roll, and by providing the nip roll, the adhesion of the base material 2 to the film-forming rollers 19 and 20 is improved. Thereby, heat exchange is efficiently performed between the base material 2 and the film forming rollers 19 and 20, and there is an advantage that film uniformity is improved and heat wrinkles are suppressed.

In such a manufacturing apparatus 10, the base material 2 is disposed on a pair of film forming rollers (film forming rollers 19 and 20) so that the surfaces of the base material 2 face each other. By disposing the base material 2 in this manner, a pair of film-forming rollers (film-forming rollers 19) is formed when plasma is generated by performing discharge in the facing space between the film-forming roller 19 and the film-forming roller 20. And 20) it is possible to simultaneously form the respective surfaces of the substrate 2 existing between them. That is, according to such a manufacturing apparatus 10, the stress relaxation layer component is deposited on the surface of the substrate 2 on the film formation roller 19 by the plasma CVD method, and further, the stress relaxation layer is formed on the film formation roller 20. Since components can be deposited, a stress relaxation layer can be efficiently formed on the surface of the substrate 2.

As the feed roller 12 and the transport rollers 13 to 18 used in the manufacturing apparatus 10, known rollers can be appropriately used. The winding roller 25 is not particularly limited as long as the optical film 1 having the stress relaxation layer 3 formed on the substrate 2 can be wound, and a known roller may be used as appropriate. it can. Further, the feed roller 12 and the take-up roller 25 may be a turret type. The turret may be multiaxial with two or more axes, and may have a structure in which only some of the axes can be opened to the atmosphere.

Further, as the gas supply pipe 21 and the vacuum pump, those capable of supplying or discharging the raw material gas at a predetermined speed can be appropriately used.

The gas supply pipe 21 serving as a gas supply means is preferably provided in one of the facing spaces (discharge region, film formation zone) between the film formation roller 19 and the film formation roller 20, and is a vacuum serving as a vacuum exhaust means. A pump (not shown) is preferably provided on the other side of the facing space. In this way, by providing the gas supply pipe 21 as the gas supply means and the vacuum pump as the vacuum exhaust means, the film formation gas is efficiently supplied to the facing space between the film formation roller 19 and the film formation roller 20. It is excellent in that the film formation efficiency can be improved.

In FIG. 2, the gas supply pipe 21 is provided on the center line between the film formation roller 19 and the film formation roller 20. However, the present invention is not limited to this. You may shift | deviate to either one side from the centerline between the rollers 20, and you may shift | deviate from the centerline in the left-right direction. By shifting the gas supply pipe 21 from the center line between the film formation roller 19 and the film formation roller 20, the gas supply pipe 21 is closer to one film formation roller and farther from the other film formation roller. The film composition formed on the film forming roller 19 and the film composition formed on the film forming roller 20 become different, and the position of the gas supply pipe 21 may be appropriately shifted when it is desired to change the film quality. Further, the gas supply pipe 21 may be appropriately separated from or closer to the film forming roller on the center line (the arrangement position may be moved on the center line in the vertical direction). There is an advantage that particles can be prevented from adhering to the gas supply pipe 21 by moving the gas supply pipe 21 away from the center axis of the film forming roller and separating the gas supply pipe 21 from the discharge space. There is an advantage that the film forming rate can be improved by bringing the film closer to the discharge space on the central axis of the film forming roller.

In FIG. 2, there is one gas supply pipe 21, but there may be a plurality of gas supply pipes 21, and different supply gases may be discharged from each nozzle.

Furthermore, as the plasma generating power source 22, a known power source for a plasma generating apparatus can be used as appropriate. Such a power source 22 for generating plasma supplies power to the film forming roller 19 and the film forming roller 20 connected thereto, and makes it possible to use them as a counter electrode for discharging. As such a plasma generation power source 22, since it is possible to perform plasma CVD more efficiently, a power source (AC power source or the like) that can alternately reverse the polarity of a pair of film forming rollers is used. It is preferable to use it.

Further, such a plasma generating power source 22 is preferably capable of performing plasma CVD more efficiently, so that the applied power is preferably in the range of 100 W to 20 kW, and in the range of 100 W to 10 kW. More preferably. In addition, as the plasma generating power source 22, it is possible to perform plasma CVD more efficiently, so that the AC frequency is preferably in the range of 50 Hz to 13.56 MHz, and in the range of 50 Hz to 500 kHz. More preferably.

Also, from the viewpoint of stabilizing the plasma process, a high frequency power source in which both the high frequency current wave and the voltage wave are sine waves may be used.

In FIG. 2, a single power source for generating plasma 22 supplies power to both film forming rollers 19 and 20 (both film forming roller power supply), but the present invention is not limited to such a configuration. The film roller may be supplied with power (one-side film formation roller power supply) and the other film formation roller may be grounded.

Further, as a method for supplying power to the film forming roller, it is possible to supply power from only one end of the roller, or to supply power from both ends of the roller. In the case of supplying a high frequency band, it is possible to supply both ends of the roller because uniform supply is possible.

Further, as a feeding method, two-frequency feeding may be performed in which different frequencies are applied, and one film-forming roller and the other film-forming roller may be applied even when two different frequencies are applied to one film-forming roller. A different frequency may be applied. By such two-frequency power feeding, the plasma density can be increased and the film formation rate can be improved.

Although not shown in FIG. 2, the plasma emission intensity in the discharge space is monitored from the outside, and if the desired emission intensity is not obtained, the distance between the magnetic fields (distance between the opposing rollers), the magnetic field intensity, and the power applied to the power source In addition, a feedback circuit that adjusts the power supply frequency, the amount of supplied gas, and the like to obtain a desired plasma emission intensity may be provided. By having such a feedback circuit, film formation / production can be stabilized.

Also, as the magnetic field generators 23 and 24, known magnetic field generators can be used as appropriate. Furthermore, as the base material 2, what formed the stress relaxation layer 3 previously on the cyclic polyolefin film can be used. As described above, by using the substrate 2 in which the stress relaxation layer 3 is formed in advance, the thickness of the stress relaxation layer 3 can be increased.

Using the manufacturing apparatus 10 shown in FIG. 2, a discharge is generated between a pair of film forming rollers (film forming rollers 19 and 20) while supplying a film forming gas (such as a raw material gas) into the film forming chamber 28. Thus, the film forming gas (raw material gas or the like) is decomposed by plasma, and the film forming layer is formed on the surface of the base material 2 on the film forming roller 19 and the surface of the base material 2 on the film forming roller 20 by the plasma CVD method. It is formed by. At this time, a racetrack-shaped magnetic field is formed in the vicinity of the roller surface facing the facing space (discharge region) along the length direction of the roller axes of the film forming rollers 19 and 20, and the plasma is converged on the magnetic field. By repeating this process by changing one or more of the film formation conditions to form a second film formation layer, a third film formation layer, and film formation under different conditions, You may form the stress relaxation layer from which the composition of the constituent atom changed continuously.

Next, the film forming gas for forming the stress relaxation layer will be described.

As the film forming gas, a reactive gas may be used in addition to the source gas. As such a reactive gas, a gas that reacts with the raw material gas to become an inorganic compound such as an oxide can be appropriately selected and used. Since the stress relaxation layer 3 contains oxygen, for example, oxygen and ozone can be used as the reactive gas, and oxygen is preferably used from the viewpoint of simplicity. In addition, a reactive gas for forming a nitride may be used. For example, nitrogen or ammonia can be used. These reaction gases can be used alone or in combination of two or more. For example, when forming an oxynitride, the reaction gas for forming an oxide and a nitride are formed. Can be used in combination with the reaction gas for

As the film forming gas, a carrier gas may be used as necessary in order to supply the source gas into the film forming chamber 28. Further, as a film forming gas, a discharge gas may be used as necessary in order to generate plasma discharge. As such carrier gas and discharge gas, known ones can be used as appropriate, and for example, rare gases such as helium, argon, neon, xenon, hydrogen, and nitrogen can be used.

The above-described manufacturing apparatus 10 shown in FIG. 2 is used to contain a silicon atom (Si), an oxygen atom (O), and a carbon atom (C), and in the C1s spectral region measured by X-ray photoelectron spectroscopy. Derived from the C—C bond relative to the sum of peak intensities derived from each bond of C—C, C—SiO, C—O, C═O and C (═O) —O at each measurement position, obtained from the depth profile It is possible to form a stress relaxation layer in which the average value X _{AVE in the} thickness direction of the ratio X (%) of the peak intensity is 1% or more and 40% or less.

Method for controlling the composition of the stress relaxation layer, that is, the type of atoms contained, the values of [C] (at%) and [C _AVE ] (at%), and the values of X (%) and X _AVE (%) Is not particularly limited, but the power of the plasma generation power source, the conveyance speed, the type of source gas used, the amount of source gas used, the amount of oxygen gas used, the source gas and oxygen gas used It is preferable to use a method in which the ratio, the degree of vacuum in the vacuum chamber, the conveyance speed, and the like are appropriately combined and controlled.

The pressure in the vacuum chamber (degree of vacuum) can be adjusted as appropriate according to the type of source gas. Here, the degree of vacuum is preferably 0.5 Pa or more and 50 Pa or less.

Here, when the AC power source as described above is used, the power of the plasma generating power source 22 can be appropriately adjusted according to the type of source gas, the pressure in the vacuum chamber, and the like. Further, in such a plasma CVD method, an electrode drum (in this embodiment, the film forming roller 19) connected to the plasma generating power source 22 for discharging between the film forming roller 19 and the film forming roller 20. The electric power to be applied to the gas can be adjusted as appropriate according to the type of the source gas, the pressure in the vacuum chamber, and the like. On the other hand, it is preferable to set it as 1 kW or more and 10 kW or less, for example.

The conveyance speed (line speed) of the base material 2 can be appropriately adjusted according to the type of raw material gas, the pressure in the vacuum chamber, and the like. Here, the conveyance speed is preferably 0.25 m / min or more, and more preferably 0.5 m / min or more. Moreover, it is preferable that a conveyance speed shall be 100 m / min or less, and it is more preferable to set it as 60 m / min or less.

The composition of the stress relaxation layer, that is, the type of atoms contained, the values of [C] (at%) and [C _AVE ] (at%), and the values of X (%) and X _AVE (%) are, for example, It is particularly preferable to control within the scope of the present invention by employing the following methods (1) to (4).

(1) Control by plasma CVD source gas It is possible to control by appropriately using plasma CVD source materials having different ratios of carbon, hydrogen, oxygen and silicon in the molecule.

Specifically, as a raw material for plasma CVD, an organosilicon compound having a low Si—C bond ratio in the molecule is preferably used. The number of Si—C bonds in one molecule in these organosilicon compounds is preferably 2 or less, more preferably 1 or 0, per one Si atom in one molecule.

Specifically, rather than disiloxanes such as hexamethyldisiloxane and tetramethyldisiloxane, cyclic siloxanes such as octamethylcyclotetrasiloxane and tetramethylcyclotetrasiloxane, and Si such as tetramethoxysilane and methyltrimethoxysilane An alkoxysilane containing one per molecule is preferably used. These compounds can be used individually by 1 type or in combination of 2 or more types.

Here, as the supply amount of the source gas increases, X _AVE (%) increases.

(2) Control by supply amount of oxygen gas which is reaction gas It is possible to control by increasing / decreasing the supply amount of oxygen gas which is a reaction gas supplied during CVD film formation.

Specifically, when forming the stress relaxation layer containing silicon atoms, oxygen atoms and carbon atoms by oxidizing the preferred raw materials, the supply amount of oxygen gas is suppressed to the extent that it is not completely oxidized, and conversely It is preferable to control by supplying a certain amount of oxygen gas to the raw material gas so that excessive carbon does not remain in the stress relaxation layer.

Here, [C _AVE ] (at%) decreases as the supply amount of oxygen gas increases.

(3) Control of addition amount of inert gas During film formation, an inert gas such as nitrogen, argon, or helium is supplied as necessary, and the supply amount of this inert gas is adjusted to thereby reduce the stress relaxation layer. It is possible to control by stabilizing the plasma at the time of forming and adjusting the oxidation reaction. However, the present invention is not limited to using an inert gas.

(4) Control of distance between electrodes in plasma discharge It can also be controlled by continuously changing the distance between electrodes for generating plasma discharge. In the case of using the apparatus in which the pair of roll electrodes face each other, the plasma space generated on the surface of the base material in contact with the electrodes is continuously changed, so that the distance between the electrodes is continuously changed. The composition in the stress relaxation layer can be continuously changed by changing the film forming conditions.

As described above, as a more preferable aspect of the present embodiment, the stress relaxation layer according to the present invention is formed by the plasma CVD method using the plasma CVD apparatus (roll-to-roll method) having the counter roller electrode shown in FIG. It is characterized by forming a film. This is stress relaxation that can improve crack resistance, durability in high temperature and high humidity environment, and adhesion of cyclic polyolefin film when mass-produced using plasma CVD equipment (roll-to-roll system) with opposed roller electrode This is because the layer can be manufactured efficiently.

<Cyclic polyolefin film>
The optical film which concerns on one form of this invention has a cyclic polyolefin film. In this specification, the cyclic polyolefin film represents a film containing 50% by mass or more of the cyclic polyolefin with respect to the total mass of the resin film. Here, the “resin film” refers to a resin film itself that can be formed from a resin composition containing a cyclic polyolefin, and does not include a stress relaxation layer or other layers that can be optionally included. This is because when the content of the cyclic polyolefin is less than 50% by mass, it is not possible to obtain excellent properties such as transparency, heat resistance and electrical characteristics derived from the cyclic polyolefin. From the same viewpoint, the content of the cyclic polyolefin is preferably 80% by mass or more, and more preferably 90% by mass or more (upper limit 100% by mass).

(Cyclic polyolefin)
The cyclic polyolefin used in the present invention is made of a polymer resin containing an alicyclic structure. The cyclic polyolefin may be one obtained by polymerizing or copolymerizing a cyclic olefin, or may be obtained by addition copolymerization of a cyclic olefin and a monomer other than the cyclic olefin. The unsaturated bond in the molecule may be changed to a saturated bond.

The cyclic polyolefin is not particularly limited, and a known one can be used. Examples of the cyclic polyolefin include paragraphs “0015” to “0062” of JP-A-2004-67984, paragraphs “0005” to “0007” of JP-A-2005-254812, and paragraphs of JP-A-2008-274136. “0016” to “0052”, paragraphs “0017” to “0036” of Japanese Patent Application Laid-Open No. 2014-106338, paragraphs “0063” to “0066” of Japanese Patent Application Laid-Open No. 2015-209487, and International Publication No. 2007/043885. However, it is not limited to those described in paragraphs “0404” to “0421”.

As examples of the cyclic olefin forming a cyclic olefin, norbornene, dicyclopentadiene, tetracyclododecene, ethyl tetracyclododecene, ethylidene tetracyclododecene, tetracyclo [7.4.0.1 ^10,13. 0 ^2,7 ] trideca-2,4,6,11-tetraene and other unsaturated hydrocarbons and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- Unsaturated hydrocarbons having a monocyclic structure such as (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene And derivatives thereof, and those obtained by hydrogenation reaction thereof, but are not limited thereto.

The cyclic polyolefin according to one embodiment of the present invention is preferably a cyclic polyolefin having a polar group.

Examples of the polar group include a hydroxy group, an alkoxyl group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an aryloxycarbonyl group, a cyano group, and an amide. Groups, imide ring-containing groups, triorganosiloxy groups, triorganosilyl groups, amino groups, acyl groups, alkoxysilyl groups having 1 to 10 carbon atoms, sulfonyl-containing groups, and carboxy groups. These polar groups will be described more specifically. Examples of the alkoxyl group include a methoxy group and an ethoxy group; examples of the acyloxy group include an alkylcarbonyloxy group such as an acetoxy group and a propionyloxy group; Arylcarbonyloxy groups such as benzoyloxy groups; examples of alkoxycarbonyl groups include methoxycarbonyl groups and ethoxycarbonyl groups; examples of aryloxycarbonyl groups include phenoxycarbonyl groups, naphthyloxycarbonyl groups, and fullerenes. Examples of the triorganosiloxy group include trimethylsiloxy group and triethylsiloxy group; examples of the triorganosilyl group include: Example, if a trimethylsilyl group, triethylsilyl group and the like; examples of the amino group, for example a primary amino group and the like; the alkoxysilyl group, for example a trimethoxysilyl group, triethoxysilyl group, and the like. Among these, an alkoxycarbonyl group is preferable and a methoxycarbonyl group is more preferable.

Examples of the cyclic polyolefin according to the present invention include (co) polymers represented by the following formula.

(Wherein R ¹ to R ⁴ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms or a polar group, and the number of substituted or unsubstituted carbon atoms. The hydrocarbon group of 1 to 30 may be bonded via a linking group having an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, and ^{two of} R ¹ and R ² or R ³ and R ⁴ are bonded. May form a divalent hydrocarbon group, may form a carbocycle or a heterocycle, and each of the plurality of R ¹ to R ⁴ may be the same or different. And at least one of R ¹ to R ⁴ is a polar group, and p and m each independently represents an integer of 0 or more.)
The polar group is the same as that described above.

Examples of the halogen atom include a fluorine atom, a chlorine atom and a bromine atom.

Examples of the hydrocarbon group having 1 to 30 carbon atoms include alkyl groups such as methyl group, ethyl group and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group. Groups; aromatic groups such as phenyl, biphenyl, naphthyl, and anthracenyl groups; These hydrocarbon groups may be substituted, and examples of the substituent include halogen atoms such as fluorine atom, chlorine atom and bromine atom, phenylsulfonyl group and the like.

The substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms may be directly bonded to the ring structure or may be bonded via a linking group. Examples of the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms such as an alkylene group represented by the formula: — (CH ₂ ) _m — (m is an integer of 1 to 10), or an oxygen atom. , A linking group containing a nitrogen atom, a sulfur atom or a silicon atom. Specific examples of the linking group containing an oxygen atom, nitrogen atom, sulfur atom or silicon atom include a carbonyl group [—CO—], a carbonyloxy group [—COO—], an oxycarbonyl group [—OCO—], a sulfonyl group [ —SO ₂ —], ether bond [—O—], thioether bond [—S—], imino group [—NH—], amide bond [—NHCO—, —CONH—], siloxane bond [—OSi (R ₂ )-(Wherein R is an alkyl group such as a methyl group or an ethyl group)], and a group in which two or more of these groups are linked.

^{Two of} R ¹ and R ² or R ³ and R ⁴ may be bonded to form a divalent hydrocarbon group, which may form a carbocyclic or heterocyclic ring, but is preferably not formed. The carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure, and the carbocyclic ring or the heterocyclic ring may be an aromatic ring or a non-aromatic ring. A ring is preferred.

At least one of R ¹ to R ⁴ is a polar group, and the group other than the polar group of R ¹ to R ⁴ is preferably a hydrogen atom.

M is preferably an integer of 0 to 3, p is preferably an integer of 0 to 3, more preferably m + p = 0 to 4, more preferably m + p = 0 to 2, and m = 1. , P = 0 is particularly preferred.

The specific monomer with m = 1 and p = 0 is preferable in that the cyclic polyolefin obtained has a high glass transition temperature and excellent mechanical strength.

Specific examples of the copolymerizable monomer used for producing the (co) polymer represented by the above formula include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

The number of carbon atoms of the cycloolefin is preferably within the range of 4 to 20, more preferably within the range of 5 to 12.

In the present invention, the cyclic polyolefin can be used alone or in combination of two or more.

The molecular weight of the cyclic polyolefin is preferably 0.2 to 5 dl / g, more preferably 0.3 to 3 dl / g in terms of intrinsic viscosity [η] _inh , and 0.4 to 1.5 dl / g. More preferably. The number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 8000 to 100,000, more preferably 10,000 to 80,000, and further preferably 12,000 to 50,000. . The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is preferably 20,000 to 300,000, more preferably 30,000 to 250,000, and further preferably 40,000 to 200,000. .

Inherent viscosity [η] _inh , number average molecular weight and weight average molecular weight are in the above ranges, so that heat resistance, water resistance, chemical resistance, mechanical properties of cyclic polyolefin, and molding as a polarizing plate protective film of the present invention Workability is improved.

The glass transition temperature (Tg) of the cyclic polyolefin that can be used in one embodiment of the present invention is usually preferably 110 ° C. or higher, more preferably 110 to 350 ° C., and more preferably 120 to 250 ° C. Is more preferable, and 120 to 220 ° C. is particularly preferable. When Tg is 110 ° C. or higher, deformation is less likely to occur due to use under high temperature conditions or secondary processing such as coating or printing. On the other hand, when Tg is 350 ° C. or lower, the case where the molding process becomes difficult is more reliably avoided, and the possibility that the resin is deteriorated by the heat during the molding process is further suppressed.

In addition, as the cyclic polyolefin, a commercially available product can be preferably used. Examples of commercial products include Arton (registered trademark) G (for example, Arton: registered trademark G7810), Arton (registered trademark) F, Arton (registered trademark) R, and Arton (registered trademark) from JSR Corporation. These are commercially available under the trade name RX and can be used.

(Additive)
The cyclic polyolefin may contain various additives as long as the effects of the present invention are not impaired. As an additive, a well-known thing can be used without being restrict | limited in particular. Preferable additives include, for example, inorganic fine particles, plasticizers, ultraviolet absorbers and the like, but are not limited thereto.

(Characteristics of cyclic polyolefin film)
[Light transmittance]
When using the cyclic polyolefin film which concerns on one form of this invention for display apparatuses, such as a liquid crystal display device and an organic EL element, it is preferable that a cyclic polyolefin film is transparent. That is, the light transmittance is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more (upper limit 100%). The light transmittance is determined by measuring the total light transmittance and the amount of scattered light using the method described in JIS K 7105: 1981, that is, using an integrating sphere light transmittance measuring device, and subtracting the diffuse transmittance from the total light transmittance. Can be calculated. However, the present invention is not limited to those satisfying the above light transmittance range.

[Elastic modulus at 90 ° C]
The elastic modulus at 90 ° C. of the cyclic polyolefin film according to one embodiment of the present invention is preferably 1.7 GPa or more. Within this range, crack resistance, durability in a high-temperature and high-humidity environment, and adhesiveness become better. This is because the durability of the cyclic polyolefin film is further improved against the stress applied during processing of the optical film and the stress generated when the optical film is aged in a high-temperature and high-humidity environment. This is considered to be because expansion is suppressed. And in the state where the optical film and other members are bonded, the durability of the cyclic polyolefin film against the stress concentrated on the interface between the two is further improved, and the fracture in the region near the interface between the two in the cyclic polyolefin film It is because it is thought that is suppressed. From the same viewpoint, the elastic modulus at 90 ° C. is preferably 1.9 GPa or more. The elastic modulus at 90 ° C. of the cyclic polyolefin film according to one embodiment of the present invention is preferably 2.7 GPa or less. Within this range, crack resistance, durability in a high-temperature and high-humidity environment, and adhesiveness become better. The reason for this is considered that the cyclic polyolefin film becomes moderately flexible, thereby improving the brittleness of the cyclic polyolefin film and suppressing the occurrence and expansion of cracks. And when placed in a high-temperature and high-humidity environment in a state where the optical film and other members are bonded, the cyclic polyolefin film can follow the expansion and contraction of the other members, and the generation and expansion of cracks, In addition, it is considered that stress concentration at the interface between the two is suppressed. From the same viewpoint, the elastic modulus at 90 ° C. is more preferably 2.5 GPa or less.

The elastic modulus at 90 ° C. is a value obtained based on the following measurement method. That is, the elastic modulus (Pa) at 90 ° C. was determined using a tensile tester, Tensilon RTA-100 manufactured by Orientec Co., Ltd., and a furnace heated to 90 ° C. in accordance with the method described in JIS K 7127: 1999. It can be obtained by conducting a tensile test in a furnace heated to 90 ° C.

In addition, the control method of the elasticity modulus at 90 degreeC of the cyclic polyolefin film is described in the manufacturing method of the cyclic polyolefin film mentioned later.

(Film thickness)
Although the film thickness of the cyclic polyolefin film which concerns on one form of this invention is not restrict | limited in particular, For example, it is preferable that they are 5 micrometers or more and 125 micrometers or less. When the film thickness is in this range, the excellent properties of the cyclic polyolefin film for optical film use are more favorably exhibited, and the generation of cracks and the expansion of cracks in a high-temperature and high-humidity environment are further reduced.

<Method for producing cyclic polyolefin film>
Although the example of the manufacturing method of the cyclic polyolefin film which can be used for one form of this invention is demonstrated, this invention is not limited to this. As a method for producing a cyclic polyolefin film, for example, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, or a hot press method can be used. From the viewpoint of suppression, suppression of optical defects such as die lines, etc., solution casting by casting is preferred.

The method for producing a cyclic polyolefin film may include a casting step in which a dope containing a cyclic polyolefin, an additive that can be optionally included, a solvent, and the like is cast on a moving support to form a cast film. preferable. Furthermore, it is preferable that the casting process includes a drying process in which drying air is blown onto the casting film.

In the case of producing by the solution casting method, the organic solvent useful for the preparation of the dope can be used without limitation as long as it dissolves the cyclic polyolefin component and the additive that can be optionally contained at the same time.

For example, as a chlorinated organic solvent, dichloromethane and the like, and as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro -2-Methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, etc. Dichloromethane, methyl acetate, ethyl acetate, and acetone can be preferably used.

In addition to the organic solvent, the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass. When the ratio of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy. Also, when the ratio of alcohol is small, the role of promoting the dissolution of cyclic polyolefin, etc. in a non-chlorine organic solvent system There is also.

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, propylene glycol monomethyl ether Etc. Among these, ethanol is preferable because it has excellent dope stability, has a relatively low boiling point, good drying properties, and no toxicity.

The content ratio of the solvent contained in the dope is preferably 1% by mass or more based on the total mass of the dope. By making the content rate of the solvent contained in dope 1 mass% or more, the fall of productivity by defect generation | occurrence | production, such as a fall of the brittleness of a film and a film to tear during manufacture, is suppressed more. From the same viewpoint, the content ratio of the solvent contained in the dope is more preferably 50% by mass or more, and further preferably 60% by mass or more. Moreover, it is preferable that the content rate of the solvent contained in dope is 95 mass% or less. By making the content ratio of the solvent contained in the dope 95% by mass or less, a decrease in transparency of the film is further suppressed. From the same viewpoint, the content ratio of the solvent contained in the dope is more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less. The content ratio of the solvent component can be appropriately adjusted from the production conditions of the film, the film thickness of the film to be produced, and the like.

In addition, the above-mentioned additives may be appropriately added to the dope.

Resin and additives are dissolved in the above solvent to prepare a dope. The dope is filtered through a filter medium and then degassed. It is preferable to use a filter medium having a collected particle diameter of 0.5 to 5 μm and a drainage time of 10 to 25 seconds / 100 mL.

The cast film refers to a film formed by casting a dope from a casting die onto a support, and refers to a dope until a film is formed by a stretching process or a second drying process described later.

(Casting process)
The casting process will be described. First, the dope is cast on a support from a casting die. Specifically, the dope is sent from the tank to the casting die by a liquid feeding pump such as a pressurized metering gear pump, and is cast from the casting port of the casting die.

As the casting die, one having an adjustable discharge port shape is preferable. Further, a pressure die that can easily make the thickness of the cast film uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be arranged side by side, and the dope may be divided and discharged. The discharge speed for discharging the dope from the casting die is preferably, for example, about 30 to 150 m / min in consideration of the balance with the moving speed of the support and productivity.

The support is preferably formed endlessly by an endless belt. The endless belt is rotated by a rotating roller driven and controlled by a power source, and the casting film on the support is moved. The moving speed of the support (the rotational speed of the endless belt) is preferably 60 to 150 m / min. By setting the moving speed of the support within this range, the cyclic polyolefin film can be produced at a higher speed.

As the support, one having a mirror-finished surface can be preferably used. As the support, a stainless steel belt (hereinafter also referred to as a stainless steel belt) or a drum whose surface is plated with a casting can be preferably used. The cast width can be 1 to 4 m. The surface temperature of the support in the casting step is preferably −50 to 40 ° C., more preferably 0 to 40 ° C., and further preferably 5 to 30 ° C. The method for controlling the temperature of the support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of bringing hot water into contact with the back side of the support.

[Evaporation suppression process]
The casting step may include an evaporation suppressing step of blowing a main solvent gas containing the main solvent in the solvent onto the casting film cast on the support before the drying step. The main solvent refers to the solvent when one kind of solvent is used, and refers to the solvent having the largest volume ratio when a mixed solvent composed of a plurality of solvents is used.

[Drying process]
The drying process included in the casting process will be described. The drying step is a step of drying the cast film as a soft film from the support to the extent that the cast film can be peeled by blowing dry air on the cast film that has undergone the evaporation suppression process. In this drying step, it is possible to adjust the elastic modulus at 90 ° C. of the produced cyclic polyolefin film by adjusting the drying speed of the film.

The elastic modulus at 90 ° C. of the cyclic polyolefin film can be adjusted by changing the drying rate of the cast film at the time of film production by the material used, the solution casting method or the melt casting method. . Among these, from the viewpoint that the controllable range is wider, control by the drying rate is preferable, and control by the drying rate in the solution pouring method is more preferable. In the control by the drying speed in the solution pouring method, shrinkage occurs due to drying of the solvent at the time of film formation, and the resin such as cyclic polyolefin is oriented. At this time, if the drying speed is increased, the orientation by drying shrinkage is oriented. It becomes stronger and the elastic modulus can be increased. On the other hand, when the drying speed is slowed, the orientation due to drying shrinkage becomes weak and the elastic modulus can be reduced. The drying speed can be controlled by the environmental temperature during drying, the temperature of hot air, the air volume, and the like.

In order for the optical film to exhibit good flatness, the residual solvent ratio when peeling the cast film from the support is preferably 20% by mass or more and 90% by mass or less. In the drying process, the drying conditions are adjusted so as to be within such a range.

The drying method is not particularly limited, and for example, a nozzle or a punch plate can be used as a drying means.

The condition of the drying air is not particularly limited as long as the casting film on the support can be dried. The temperature of the drying air is preferably 30 to 160 ° C. from the viewpoint of drying efficiency and suppression of foaming. The relative humidity of the drying air is preferably 30% RH or less, more preferably 20% RH or less, and further preferably 10% RH or less (lower limit 0%) from the viewpoint of drying efficiency. RH). As the drying air, for example, air of 50 ° C. and 10% RH is preferably used. The static pressure of the drying air is preferably 100 Pa or more. When the static pressure of the drying air is 100 Pa or more, it becomes easier to increase the elastic modulus of the cyclic polyolefin film at 90 ° C. and control it within the range defined in the present invention. From the same viewpoint, the static pressure of the drying air is preferably 1000 Pa or more, and preferably 1300 Pa or more. Moreover, it is preferable that the static pressure of a dry wind is 2500 Pa or less. When the static pressure of the drying air is 2500 Pa or less, it becomes easier to reduce the elastic modulus at 90 ° C. of the cyclic polyolefin film and control it within the range defined in the present invention. From the same viewpoint, the static pressure of the drying air is preferably 2000 Pa or less, and preferably 1900 Pa or less. An example of preferable drying conditions includes blowing dry air at 50 ° C. and 10% RH at a static pressure of 1000 to 2500 Pa, but the present invention is not limited to these conditions.

The drying means may be provided on the downstream side of the air supply means along the moving direction of the support. Moreover, the drying means may be provided at a plurality of locations.

(Other processes)
[Dope preparation process]
The dope preparation process will be described. The dope preparation step is a step of preparing the dope cast on the support from the casting die in the casting step. The method for preparing the dope is not particularly limited. For example, the dope can be prepared by adding a resin such as cyclic polyolefin into the above-described solvent using a melting pot. The content of the resin in the dope is preferably 5% by mass or more as the solid content concentration. When the resin content is 5% by mass or more as the solid content concentration, it becomes possible to dry more sufficiently on the support, and a part of the cast film remains on the support at the time of peeling, thereby causing contamination of the support. The occurrence frequency is further reduced. From the same viewpoint, the content of the resin in the dope is preferably 10% by mass or more as a solid content concentration, more preferably 15% by mass or more, and further preferably 20% by mass or more. . Moreover, it is preferable that content of resin in dope is 99 mass% or less as solid content concentration. When the content of the resin in the dope is 99% by mass or less, the viscosity of the dope becomes moderately low, so that the pressure becomes too high when the filter is clogged in the dope preparation process or cast onto the support. As a result, the frequency at which extrusion from the casting die becomes difficult is further reduced. From the same viewpoint, the content of the resin in the dope is preferably 50% by mass or less, and more preferably 40% by mass or less as the solid content concentration.

As a method of dissolving the resin in the solvent, a method of dissolving at normal pressure, a method of dissolving below the boiling point of the solvent, a method of dissolving above the boiling point of the solvent while applying pressure, JP-A-9-95544 and JP-A-9- As described in JP-A-95557 or JP-A-9-95538, a method of employing a cooling dissolution method, a method of dissolving at a high pressure as described in JP-A-11-21379, or the like may be employed. it can. In these, the method of melt | dissolving above the boiling point of a solvent while pressurizing is preferable.

The obtained dope is filtered with a filter medium, defoamed, and then sent to a casting die with a liquid feed pump. For the filtration, it is preferable to use a filter medium having a collected particle diameter of 0.5 μm or more and 5 μm or less and a drainage time of 10 seconds / 100 mL or more and 25 seconds / 100 mL or less. By filtration, it is possible to remove only aggregates and the like remaining when the resin particles are dispersed.

The dope prepared as described above is cast on a support from a casting die.

[Peeling process]
The peeling process will be described. A peeling process is a process of peeling the cast film which formed the soft film through the drying process from a support body with a peeling roll. The peeled soft film is then subjected to a second drying step, a stretching step, a heat treatment step, a winding step, and the like that can be optionally provided to produce a cyclic polyolefin film.

The temperature at the peeling position on the support is preferably 10 ° C. or higher and 40 ° C. or lower, more preferably 11 ° C. or higher and 30 ° C. or lower. In general, the peeling tension at the time of peeling the support and the casting film is preferably 245 N / m or less, but from the viewpoint that wrinkles at the time of peeling are more difficult to enter, it is 190 N / m or less. More preferably, it is more preferably 166.6 N / m or less, and particularly preferably 137.2 N / m or less. Further, from the viewpoint of obtaining better peelability, the peel tension is preferably 50 N / m or more.

[Second drying process, stretching process, heat treatment process, winding process]
The second drying step, stretching step, heat treatment step, and winding step will be described. The second drying step, the stretching step, and the heat treatment step are each a drying device that alternately conveys the peeled cast film with rollers arranged inside, and a tenter that holds and conveys both ends of the cast film. It is a step of producing a cyclic polyolefin film by performing drying, stretching, and heat treatment, respectively, using at least one of the stretching devices. Moreover, a winding process is a process of winding up the obtained cast film. Depending on the configuration of the apparatus, a plurality of steps may be performed simultaneously. In addition, since it has a drying process also in the above-mentioned casting process, the drying process performed with respect to the soft film which peeled is called the 2nd drying process for the purpose of distinguishing from the said drying process.

As a drying method in the second drying step, a method of spraying hot air on both surfaces of the cast film is generally used, but a method of heating by applying microwaves instead of hot air can also be adopted. Since the cast film is likely to cause surface unevenness due to rapid drying, it is preferable to dry from the time when the residual solvent ratio becomes 15% by mass or less, and it is more preferable to dry from the time when the residual solvent rate becomes 8% by mass or less. preferable. The drying temperature is preferably 40 to 250 ° C.

The tenter of the tenter stretching apparatus is not particularly limited, and a known tenter such as a pin tenter or a clip tenter can be used.

The stretching direction is not particularly limited, and may be a film transport direction, a direction perpendicular to the film transport direction, a film longitudinal direction, or a film width direction. Also good. In addition, the stretching operation may be performed in multiple stages, or biaxial stretching may be performed in the longitudinal direction and the width direction. In addition, when performing biaxial stretching, you may extend | stretch simultaneously and may extend in steps. In the specification of the present application, simultaneous biaxial stretching includes a case of stretching in one direction and contracting the other while relaxing the tension.

When uniaxially stretching in the width direction using a tenter stretching apparatus, the stretching ratio is not particularly limited, but the stretching ratio is 1.01 times (stretching ratio: 1%) or more and 1.50 times (stretching ratio: 50%) or less. It is more preferable that it is 1.01 times (stretching ratio: 1%) or more and 1.10 times (stretching ratio: 10%) or less, and 1.01 times (stretching ratio: 1%) or more and 1.05. It is more preferable that it is not more than double (stretching ratio: 5%).

The residual solvent ratio of the cast film when stretching with a tenter is preferably 3% by mass or more and 15% by mass or less, preferably 3% by mass or more and 8% by mass or less at the start of the tenter (at the start of stretching). It is more preferable to perform drying while applying a tenter until the residual solvent ratio of the cast film becomes 5% by mass or less. The drying temperature when stretching with a tenter is preferably 30 ° C. or more, and the glass transition temperature of the cyclic polyolefin (in the case of including a plurality of cyclic polyolefins, the glass transition temperature of these cyclic polyolefins). It is more preferable that the temperature is not higher than the highest temperature (α + 30 ° C.) 30 ° C. higher than α. The temperature within such a range varies depending on the type of cyclic polyolefin, but as preferred stretching temperatures, 30 ° C. or higher and 190 ° C. or lower, 30 ° C. or higher and 160 ° C. or lower, 50 ° C. or higher and 150 ° C. or lower, 70 degreeC or more and 140 degrees C or less etc. are mentioned.

The winding process will be described. A winding process is a process of winding up with a winder as a cyclic polyolefin film. As for the cyclic polyolefin film at the time of winding, it is preferable that the residual solvent rate in a cast film is 1 mass% or less.

The winding method is not particularly limited, and a known winding method can be employed. For example, a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, or the like can be employed. .

The winding length is not particularly limited, but is preferably 100 m or more and 8000 m or less, and is usually wound in a roll shape. Moreover, it is preferable that the width | variety of the wound cyclic polyolefin film is 1.3 m or more and 3.0 m or less.

[Surface treatment process]
For various surfaces of the cyclic olefin film, particularly on the side where the stress relaxation layer is provided, various known treatments for improving adhesion, corona discharge treatment, flame treatment, oxidation treatment, plasma treatment, etc., as necessary Can be combined.

<Other functional layers>
The optical film according to one embodiment of the present invention may have a known functional layer. As the functional layer, a hard coat layer, an anchor coat layer, a smooth layer, and the layers described in paragraphs “0036” to “0038” of JP-A-2006-289627 can be preferably used.

(Hard coat layer)
The optical film which concerns on one form of this invention may have as a hard-coat layer. Known materials, methods, and the like can be appropriately employed as the constituent material and the forming method of the hard coat layer. The formation place of the anchor coat layer is not particularly limited, but is preferably the outermost layer on the surface of the cyclic polyolefin film opposite to the surface on which the stress relaxation layer is present.

(Anchor coat layer)
The optical film according to one embodiment of the present invention may have an anchor coat layer as an easily adhesive layer for the purpose of improving adhesiveness (adhesion). As the constituent material and forming method of the anchor coat layer, the materials and methods disclosed in paragraphs “0229” to “0232” of JP2013-52561A can be appropriately employed. The formation location of the anchor coat layer is not particularly limited, but is preferably the surface of the cyclic polyolefin film, and more preferably has a configuration in which the cyclic polyolefin film, the anchor coat layer, and the stress relaxation layer are in direct contact with each other in this order.

(Smooth layer)
The optical film according to one embodiment of the present invention may have a smooth layer. The smooth layer is for flattening the rough surface of the substrate on which protrusions and the like exist, or for filling the unevenness and pinholes generated in the stress relaxation layer with the protrusions existing on the resin substrate to flatten the surface. It is a layer to be provided. The materials, methods, etc. disclosed in paragraphs “0233” to “0248” of JP2013-52561A are appropriately employed for the constituent material, forming method, surface roughness, layer thickness, etc. of the smooth layer. The location where the smooth layer is formed is not particularly limited, but is preferably the surface of the cyclic polyolefin film, and more preferably has a configuration in which the cyclic polyolefin film, the smooth layer, and the stress relaxation layer are in direct contact with each other in this order. The anchor coat layer described above may also function as a smooth layer.

<Polarizing plate protective film and polarizing plate>
The optical film according to one aspect of the present invention exhibits good crack resistance during punching and cutting of a film during polarizing plate processing, and is used in a durability test of a polarizing plate and a display device. It has high durability that can sufficiently suppress crack expansion over time in the environment. In addition, the optical film according to one embodiment of the present invention has particularly good adhesiveness particularly when bonded to a hydrophilic member such as a polyvinyl alcohol polarizer.

Thus, the optical film according to one embodiment of the present invention is a polarizing plate protective film. Further, the polarizing plate according to one embodiment of the present invention includes the optical film according to one embodiment of the present invention or the polarizing plate protective film according to one embodiment of the present invention, and the polarizing plate protection according to one embodiment of the present invention. More preferably, it includes a film.

The polarizing plate according to one embodiment of the present invention preferably has a configuration having the optical film according to one embodiment of the present invention as a polarizing plate protective film on at least one surface of the polarizer, and on one surface of the polarizer. And having the optical film according to one embodiment of the present invention as a polarizing plate protective film, and having the optical film according to one embodiment of the present invention or the cellulose triacetate film as a polarizing plate protective film on the other surface of the polarizer. Is more preferable, and it is more preferable that the optical film according to one embodiment of the present invention is provided on both surfaces of the polarizer as a polarizing plate protective film.

(Production method of polarizing plate)
The polarizing plate according to one embodiment of the present invention can be manufactured by a general method. It is preferable that the stress relaxation layer of the optical film according to one embodiment of the present invention is surface-treated by corona discharge treatment, plasma treatment, or the like and bonded to a polarizer using a known adhesive.

As a preferred example of the method for forming the polarizing plate, the following method may be mentioned. However, the present invention is not limited to this.

When the optical film according to one embodiment of the present invention is used as a polarizing plate protective film, an easy adhesion treatment such as a corona discharge treatment is performed on the stress relaxation layer of the optical film. And the surface of a polarizer and the stress relaxation layer of the optical film which concerns on one form are bonded together using a well-known adhesive agent. Similarly, an optical film according to an embodiment of the present invention that has been subjected to easy adhesion treatment such as corona discharge treatment, or other known film, using a known adhesive on the other surface of the polarizer. Paste. At this time, when the optical film according to one embodiment of the present invention is bonded to one surface of the polarizer and another known film is bonded to the other surface, either film may be bonded first. Here, when a cellulose acylate film is used on the surface opposite to the surface on which the optical film according to one embodiment of the present invention is bonded, the cellulose acylate film is subjected to alkali saponification treatment, and at least the polarizer It is preferable to attach to one surface using a completely saponified polyvinyl alcohol aqueous solution (water paste).

The polarizer is formed by forming a polyvinyl alcohol aqueous solution into a film and dyeing it by uniaxial stretching, or by dyeing and then uniaxially stretching and then preferably performing a durability treatment with a boron compound. . The thickness of the polarizer is preferably in the range of 5 to 30 μm, particularly preferably in the range of 10 to 20 μm. Further, the ethylene unit content described in JP 2003-248123 A, JP 2003-342322 A, etc. is in the range of 1 to 4 mol%, the polymerization degree is in the range of 2000 to 4000, and the saponification degree is 99. Ethylene-modified polyvinyl alcohol in the range of 0.0 to 99.99 mol% is also preferably used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73 ° C. is preferably used. A polarizer using this ethylene-modified polyvinyl alcohol film has excellent polarization performance and durability performance, and has few color spots and is particularly preferably used for a display device. As for the polarizer obtained by making it above, a protective film is normally bonded by the both sides or one side.

Corona discharge treatment is treatment performed by applying a high voltage of 1 kV or more between electrodes at atmospheric pressure and discharging. By the corona treatment, oxygen-containing polar groups (hydroxy group, carbonyl group, carboxylic acid group, etc.) are generated on the surface of the film, and the surface is hydrophilized. The corona discharge treatment can be performed using a commercially available apparatus manufactured by Kasuga Electric Co., Ltd. or Toyo Electric Co., Ltd.

The stress relaxation layer and the polarizer of the optical film according to one embodiment of the present invention are preferably bonded with an active energy ray-curable adhesive. Among the active energy ray curable adhesives, it is preferable to use an ultraviolet curable adhesive. The ultraviolet curable adhesive composition constituting the ultraviolet curable adhesive includes a photo radical polymerization composition utilizing photo radical polymerization, a photo cation polymerization composition utilizing photo cation polymerization, and photo radical polymerization and light. A hybrid composition using cationic polymerization is known. The radical photopolymerizable composition includes a radically polymerizable compound containing a polar group such as a hydroxy group and a carboxy group described in JP-A-2008-009329 and a radically polymerizable compound not containing a polar group at a specific ratio. Composition) and the like are known. In addition, as the cationic photopolymerization type composition, as disclosed in JP2011-08234A, (α) a cationic polymerizable compound, (β) a cationic photopolymerization initiator, and (γ) a wavelength longer than 380 nm. And an ultraviolet curable adhesive composition containing each component of a photosensitizer exhibiting maximum absorption in the light of (δ) and a naphthalene-based photosensitization aid. However, other ultraviolet curable adhesives may be used.

<Display device>
The optical film according to an aspect of the present invention and the polarizing plate protective film according to an aspect of the present invention have excellent crack resistance and a high temperature and high humidity environment in addition to the excellent properties of the optical film used by the cyclic polyolefin film. Both durability and adhesiveness are achieved. In addition, the optical film according to one embodiment of the present invention and the polarizing plate according to one embodiment of the present invention sufficiently suppress the crack expansion with time in a high-temperature and high-humidity environment used in a durability test of a display device or the like. High durability.

Therefore, a display device according to one embodiment of the present invention includes the optical film according to one embodiment of the present invention or the polarizing plate according to one embodiment of the present invention.

The display device is not particularly limited, but is preferably an organic EL element or a liquid crystal display device, and more preferably a liquid crystal display device.

A liquid crystal display device according to one embodiment of the present invention includes a liquid crystal cell in which a liquid crystal is sandwiched between a transparent substrate and the other transparent substrate, and directly or on the outside of at least one of these transparent substrates. Through the member, the optical film according to one embodiment of the present invention or the polarizing plate according to one embodiment of the present invention is provided.

The effect of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Production of optical film>
(Production of cyclic polyolefin film)
[Cyclic polyolefin film 1]
A main dope having the following composition was prepared. First, dichloromethane and ethanol were added to the pressure dissolution tank. The cyclic polyolefin resin 1 was added to a pressure dissolution tank containing a mixed solution of dichloromethane and ethanol with stirring. This was completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope was prepared by filtration using 244. As cyclic polyolefin resin, ARTON (registered trademark) made by JSR Corporation
G7810 was used. The cyclic polyolefin resin 1 is a resin having an alkoxycarbonyl group having a glass transition temperature of 178 ° C.

[Composition of main dope]
-Cyclic polyolefin resin (ARTON (registered trademark) G7810, manufactured by JSR Corporation, Mw = 140000) 100 parts by mass,
-Dichloromethane (SP value: 20) 200 parts by mass,
-Ethanol (SP value: 26) 10 mass parts.

Then, using an endless belt casting apparatus, the dope was uniformly cast on a stainless steel belt support at a temperature of 31 ° C. and a width of 1800 mm. The temperature of the stainless steel belt was controlled at 28 ° C. On the stainless steel belt support, the solvent was evaporated until the amount of residual solvent in the cast (cast) film reached 40% by mass. As drying conditions at this time, drying air of 50 ° C. and 10% RH was sprayed at a static pressure of 1000 Pa. Subsequently, the film was peeled off from the stainless steel belt support with a peeling tension of 110 N / m. The peeled film was stretched 5% in the width direction using a tenter while applying heat at 140 ° C. The residual solvent at the start of stretching was 15% by mass.

Then, drying was completed while transporting the drying zone with a large number of rollers, and the ends sandwiched between tenter clips were trimmed, and then wound up. The drying temperature was 130 ° C. and the transport tension was 100 N / m.

As described above, a cyclic polyolefin film 1 having a thickness of 25 μm was produced.

[Cyclic polyolefin film 2]
In the production of the cyclic polyolefin film 1, the drying conditions of the cast film on the stainless steel belt support were changed in the same manner except that the drying air at 50 ° C. and 10% RH was sprayed at a static pressure of 2500 Pa. A cyclic polyolefin film 2 having a thickness of 25 μm was produced.

[Cyclic polyolefin film 3]
In the production of the cyclic polyolefin film 1, the drying conditions of the cast film on the stainless steel belt support were changed except that the drying air of 50 ° C. and 10% RH was blown at a static pressure of 1300 Pa. A cyclic polyolefin film 3 having a thickness of 25 μm was prepared.

[Cyclic polyolefin film 4]
In the production of the above-mentioned cyclic polyolefin film 1, the drying conditions of the cast film on the stainless steel belt support were changed except that the drying air of 50 ° C. and 10% RH was blown at a static pressure of 1700 Pa. A cyclic polyolefin film 4 having a thickness of 25 μm was produced.

[Cyclic polyolefin film 5]
In the production of the above-mentioned cyclic polyolefin film 1, the drying conditions of the cast film on the stainless steel belt support were changed except that the drying air of 50 ° C. and 10% RH was blown at a static pressure of 1900 Pa. A cyclic polyolefin film 5 having a thickness of 25 μm was prepared.

(Formation of stress relaxation layer: Roller CVD method)
One of the produced cyclic polyolefin films was selected as the resin substrate. Using the inter-roller discharge plasma CVD apparatus to which the magnetic field shown in FIG. 2 is applied (this method is referred to as “roller CVD method”), one surface of the cyclic polyolefin film is brought into contact with the film forming roller. Then, a cyclic polyolefin film was attached to the apparatus. Next, as film formation conditions (plasma CVD conditions), the frequency of the power source for plasma generation is set to 70 kHz, the conveyance speed, the supply amount of tetramethylcyclotetrasiloxane (TMCTS) as a raw material gas, and the supply amount of oxygen gas (O ₂ ) Film formation was performed under the conditions shown in Table 1 below, with the applied power (applied power) from the plasma generating power source for the degree of vacuum in the vacuum chamber and the effective film forming width of 1 m. In this way, a stress relaxation layer was formed on the surface opposite to the surface of the cyclic polyolefin film that was in contact with the film-forming roller so that the final layer thickness was 140 nm by a film thickness measurement method described later. .

Thus, optical films according to Examples 1 to 15 and Comparative Examples 1 to 4 were produced. The combinations of the cyclic polyolefin film and the stress relaxation layer used in forming each optical film are summarized in Table 1 below. In Table 1, the unit of the supply amount of the source gas and the supply amount of the oxygen gas was sccm (Standard Cubic Centimeter per Minute).

<Evaluation of cyclic polyolefin film and stress relaxation layer>
(Elastic modulus of cyclic polyolefin film at 90 ° C)
The elastic modulus at 90 ° C. of each cyclic polyolefin film was determined according to the method described in JIS K 7127: 1999, using a tensile tester Tensilon RTA-100 manufactured by Orientec Co., Ltd., and a furnace heated to 90 ° C. The measurement was performed by performing a tensile test in a furnace heated to 90 ° C.

(Composition analysis of stress relaxation layer)
[Measurement of element distribution profile]
For each of the formed stress relaxation layers, XPS depth profile measurement was performed under the following conditions to obtain a carbon distribution curve, a silicon distribution curve, and an oxygen distribution curve with respect to the distance from the surface of the thin film layer in the layer thickness direction.

≪XPS depth profile measurement≫
Etching ion species: Argon (Ar ⁺ )
Etching rate (SiO ₂ thermal oxide film equivalent value): 0.05 nm / sec,
Etching interval (SiO ₂ equivalent value): 2 nm
X-ray photoelectron spectrometer: manufactured by Thermo Fisher Scientific, model name “VG Theta Probe”,
-Irradiation X-ray: single crystal spectroscopy AlKα,
X-ray spot and its size: 800 μm × 400 μm ellipse.

As described above, a carbon distribution curve, a silicon distribution curve, and an oxygen distribution curve were obtained by performing a wide scan spectrum analysis for measuring the entire region of the stress relaxation layer. Here, the depth from the outermost surface side in the layer thickness direction of the stress relaxation layer when the composition ratio of oxygen atoms (O) which is a part of the total composition forming the stress relaxation layer is 30 at% or less is calculated. And the position of the interface with the substrate. And the silicon atom of the stress relaxation layer, the oxygen atom, and the carbon atom were analyzed as follows.

[Analysis of silicon, oxygen and carbon atoms in stress relaxation layer]
Since the peak intensities derived from silicon atoms, oxygen atoms and carbon atoms were confirmed by X-ray photoelectron spectroscopy, each stress relaxation layer contained silicon atoms (Si), oxygen atoms (O) and carbon atoms (C). It was confirmed to contain.

In addition, for each measurement position of the depth in the layer thickness direction of each stress relaxation layer, the sum of the composition ratios converted from the ratio of the peak intensities derived from silicon atoms, oxygen atoms and carbon atoms obtained by X-ray photoelectron spectroscopy The ratio [C] (at%) of carbon atoms when the amount was 100 at% was calculated. Then, from the value of each [C] (at%) at each measurement position of the depth in the layer thickness direction of the stress relaxation layer, the average value [C _AVE ] (at %) Was further calculated.

And about the carbon atom, the binding state of carbon was analyzed by the high resolution spectrum (narrow scan analysis) of C1s. Specifically, for each measurement position of the depth in the thickness direction of the stress relaxation layer, (1) C—C, (2) C—SiO, (3) C—O, (4) C═O, and (5) The spectrum was divided into five bonds such as C (= O) -O, and the peak intensity ratio of each spectrum was calculated. For each measurement position in the film thickness direction of the stress relaxation layer, when the sum of the peak intensity ratios of (1) to (5) is 100%, the peak intensity derived from the CC bond in (1) The ratio X (%) was calculated. And _XAVE (%) which is an average value in the film thickness direction of X (%) was further calculated from the value of each X (%) in each measurement position of the depth of the stress relaxation layer in the layer thickness direction. In this measurement, the analysis of peak intensity was performed using data analysis software PeakFit (manufactured by SYSSTAT Software Inc.).

Table 2 below shows the elastic modulus (GPa) at 90 ° C. of each cyclic polyolefin film, and [C _AVE ] (at%) and X _AVE (%) of each stress relaxation layer.

(Thickness of stress relaxation layer)
The thickness of each stress relaxation layer was measured by observing the depth from the outermost surface to the interface with the substrate in the stacking direction of the stress relaxation layer by cross-sectional observation using a transmission electron microscope (TEM). In this measurement, the layer thickness was measured arbitrarily at 10 locations, and the average value was taken as the layer thickness.

[TEM image of cross section in layer thickness direction]
As a cross-sectional TEM observation, the observation sample was subjected to TEM observation after a thin piece was produced by the following focused ion beam (FIB) processing apparatus. Here, when the sample was continuously irradiated with the electron beam, a contrast difference appeared between the portion that received the electron beam damage and the portion that did not, so the thickness of the stress relaxation layer was measured based on the contrast difference.

≪FIB processing≫
Apparatus: SMI2050 manufactured by Seiko Instruments Inc. (SII),
・ Processed ions: Ga (30 kV),
Sample thickness: 100-200 nm.

≪TEM observation≫
Apparatus: JEM2000FX (acceleration voltage: 200 kV) manufactured by JEOL Ltd.

<Evaluation of optical film>
(Crack resistance)
Five optical films obtained as described above are overlapped with the stress relieving layer facing upward (with the same configuration) and punched 100 with a 10 cm square Thomson blade. The number of detected corners (n) was divided by the number of observed corners (m), the punching defect occurrence rate was calculated as a percentage as follows, and evaluated according to the following evaluation criteria. The crack resistance represents a better result as the numerical value of the punching failure occurrence rate (%) is smaller, and rank 3 or higher is a desirable crack resistance. These results are shown in Table 2 below;

≪Evaluation criteria≫
5: Punching defect occurrence rate (%) is 0% or more and less than 5%.
4: The punching defect occurrence rate (%) is 5% or more and less than 15%.
3: Punching defect occurrence rate (%) is 15% or more and less than 25%.
2: The punching defect occurrence rate (%) is 25% or more and less than 35%.
1: The punching defect occurrence rate (%) is 35% or more.

(Adhesiveness)
[Formation of polarizing plate]
≪Production of polarizer≫
A 70 μm thick polyvinyl alcohol film was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution of 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. . The obtained film was uniaxially stretched under conditions of a stretching temperature of 55 ° C. and a stretching ratio of 5 times. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 15 μm.

≪Preparation of UV curable adhesive liquid≫
Each of the following components was mixed and then defoamed to prepare an ultraviolet curable adhesive solution. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.

-45 parts by mass of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,
・ Epolide (registered trademark) GT-301 (Daicel Co., Ltd. alicyclic epoxy resin) 40 parts by mass,
・ 15 parts by mass of 1,4-butanediol diglycidyl ether,
-Triarylsulfonium hexafluorophosphate 2.3 parts by mass,
・ 9,10-dibutoxyanthracene 0.1 parts by mass,
・ 2.0 parts by mass of 1,4-diethoxynaphthalene.

≪Preparation of polarizing plate≫
According to the following method, each polarizing plate was produced using each of the obtained optical films as a polarizing plate protective film. Each polarizing plate was created by the following method.

First, as the first polarizing plate protective film, the produced optical film was prepared, and the surface of the stress relaxation layer was subjected to corona discharge treatment. The corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the prepared UV curable adhesive solution is applied to the surface of the stress-relieving layer subjected to the corona discharge treatment of the first polarizing plate protective film with a bar coater so that the film thickness after curing is about 3 μm. To form an ultraviolet curable adhesive layer. The produced polarizer (thickness 15 μm) was bonded to the obtained ultraviolet curable adhesive layer.

Next, as the second polarizing plate protective film, a film of the same type as the optical film was further prepared, and the surface of the stress relaxation layer was subjected to corona discharge treatment. The conditions of the corona discharge treatment were a corona output intensity of 2.0 kW and a speed of 18 m / min.

Subsequently, on the surface of the stress relaxation layer subjected to the corona discharge treatment of the second polarizing plate protective film, the prepared ultraviolet curable adhesive liquid is applied with a bar coater so that the film thickness after curing is about 3 μm. Coating was performed to form an ultraviolet curable adhesive layer.

Then, a polarizer bonded to one surface of the first polarizing plate protective film is bonded to the ultraviolet curable adhesive layer, and the first polarizing plate protective film / UV curable adhesive layer / polarizer. / The ultraviolet-ray curable adhesive layer / The laminated body with which the 2nd polarizing plate protective film was laminated | stacked was obtained. In that case, it bonded so that the longitudinal direction at the time of manufacture of a 1st polarizing plate protective film and the absorption axis (longitudinal direction) of a polarizer might become mutually parallel.

Thereafter, ultraviolet rays are irradiated from both sides of the laminate using an ultraviolet irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems) so that the integrated light quantity becomes 750 mJ / cm ^2. Each of the ultraviolet curable adhesive layers was cured to produce a polarizing plate.

[Adhesion test]
A bending test was performed on each of the produced polarizing plates. The bending test of each polarizing plate was performed by the following method.

First, an operation of bending a polarizing plate punched out to a size of 10 cm in length and 10 cm in width to 100 ° so that one surface side is convex was repeated 100 times. And about the polarizing plate after a bending test, the adhesiveness of a polarizing plate protective film and a polarizer was evaluated in accordance with the following evaluation criteria. The adhesiveness represents a better result as the degree of peeling between the polarizing plate protective film and the polarizer is smaller, and rank 3 or higher is desirable adhesiveness. These results are shown in Table 2 below;
≪Evaluation criteria≫
5: The polarizing plate protective film and the polarizer are not peeled off at all.
4: Floating from the polarizer of the polarizing plate protective film is slightly generated at the peripheral edge,
3: The polarizing plate protective film and the polarizer are peeled off in a range of less than 5 mm from the peripheral portion.
2: The polarizing plate protective film and the polarizer are peeled in the range of 5 mm or more and less than 10 mm from the peripheral portion.
1: The polarizing plate protective film and the polarizer are separated within a range of 10 mm or more from the peripheral portion.

(Durability under high temperature and high humidity)
A commercially available VA type liquid crystal display device (42 inch type, direct type backlight) is used, and the backlight side polarizing plate and the viewing side polarizing plate of the liquid crystal cell are peeled off. Each polarizing plate produced in the same manner is bonded to both sides of the liquid crystal cell, and the polarizing direction of the polarizing plate is such that the absorption axis is oriented in the same direction as the previously bonded polarizing plate. A liquid crystal display device was manufactured. Here, the polarizing plate bonded to the liquid crystal cell was the same on both sides.

Durability in a high temperature and high humidity environment is as follows. The liquid crystal display device thus produced was subjected to a durability test for 500 hours after lighting a direct type backlight in a 40 ° C., 90% relative humidity environment. 24 hours after turning on the backlight at room temperature, the degree of light leakage when displaying the screen in black was observed and evaluated according to the following evaluation criteria. The durability under a high temperature and high humidity environment represents a better result as the degree of light leakage is smaller, and rank 3 or higher is a desirable durability. These results are shown in Table 2 below;
≪Evaluation criteria≫
4: At a level where light leakage is hardly visible,
3: Light leakage is slightly visible but at an acceptable level.
2: The light leakage is visible and is an unacceptable level.
1: Light leakage is clearly visible and is not acceptable.

The optical film according to the present invention contains a cyclic polyolefin film and silicon atoms (Si), oxygen atoms (O) and carbon atoms (C) disposed thereon, and an average value of the C—C bond ratio. And a stress relaxation layer having X _AVE of 1% to 40%. From the results of Table 2, the optical film according to each example of the present invention is more resistant to cracking than the optical film according to each comparative example in which the average value X _AVE of the C—C bond ratio is outside the scope of the present invention. It was confirmed that the film was excellent in durability and adhesion under high temperature and high humidity.

Further, a group consisting of optical films 3, 7, 12, and 16 as examples, a group consisting of optical films 4, 8, 13, and 17 as examples, a group consisting of optical films 9 and 14 as examples, and From the comparison of the evaluation results within the same group of the group consisting of optical films 5, 10, 15 and 18 as examples, the optical film according to the present invention has an elastic modulus at 90 ° C. of the cyclic polyolefin film of 1. It was confirmed that when it was 9 GPa or more and 2.5 GPa or less, it was further excellent in crack resistance, durability in a high temperature and high humidity environment, and adhesiveness.

This application is based on Japanese Patent Application No. 2016-225322 filed on November 18, 2016, the disclosure of which is incorporated by reference in its entirety.

1 optical film,
2 base material,
3 Stress relaxation layer,
10 Production equipment,
12 Feeding roller,
13-18 transport rollers,
19, 20 Deposition roller,
21 gas supply pipe,
22 Power source for plasma generation,
23, 24 Magnetic field generator,
25 take-up roller,
27, 29 Transport system chamber,
28 Deposition chamber,
30, 31 connection part.

Claims (6)

1. A cyclic polyolefin film;
   A stress relieving layer disposed on the cyclic polyolefin film,
   The stress relaxation layer contains silicon atoms (Si), oxygen atoms (O) and carbon atoms (C), and
   C—C, C—SiO, C—O, C═O and C (═O) — at each measurement position, obtained from the depth profile of the C1s spectral region measured by X-ray photoelectron spectroscopy of the stress relaxation layer. An optical film having an average value X _{AVE in the} thickness direction of a ratio X (%) of peak intensities derived from C—C bonds to a sum of peak intensities derived from each bond of O being 1% or more and 40% or less.
2. The optical film according to claim 1, wherein the cyclic polyolefin film has an elastic modulus at 90 ° C of 1.9 GPa or more and 2.5 GPa or less.
3. The optical film according to claim 1, wherein the X _AVE is 2% or more and 20% or less.
4. A polarizing plate protective film comprising the optical film according to any one of claims 1 to 3.
5. A polarizer,
   The optical film according to any one of claims 1 to 3, or the polarizing plate protective film according to claim 4,
   A polarizing plate having
6. A display device comprising the optical film according to any one of claims 1 to 3 or the polarizing plate according to claim 5.

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