JP2017021181A - Optical film, polarizing plate, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cracking of a cured layer due to an external force, suppress phase difference variation due to contained moisture of a film substrate, and avoid deterioration of visibility at the time of image observation using polarizing-type glasses and the like, even having a film substrate that is formed of a cellulose-based resin and functions as a λ/4 film, and a low moisture permeable cured layer.SOLUTION: An optical film 16 has a film substrate 12 which is formed of a cellulose-based resin and functions as a λ/4 film, a cured layer 14 and a buffer layer 13. The cured layer 14 contains a resin having an alicyclic structure, and fine particles coated with a polymer silane coupling agent. The buffer layer 13 is formed between the film substrate 12 and the cured layer 14, and contains a resin different from the resin of the cured layer 14 and fine particles coated with the polymer silane coupling agent.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical film including a film base material made of a cellulose-based resin, a low moisture-permeable cured layer, a polarizing plate having the optical film, and an image display device having the polarizing plate.

  When an observer observes an image displayed on a liquid crystal display device through polarized glasses for observing a stereoscopic image (3D video) or polarized sunglasses (hereinafter, also referred to as “polarized glasses”), the observer When lying down, the transmission axis of polarizing glasses or the like (axis through which linearly polarized light is transmitted) is inclined with respect to the upright state, and crosstalk (luminance change, darkness) occurs. In order to reduce such crosstalk and improve image visibility, it is known to arrange a λ / 4 film on the outermost surface on the viewing side of the liquid crystal display device.

  Further, in recent years, liquid crystal display devices have been made more curved and thinner due to demands for improvement in design and miniaturization. Along with this, thinning of each member constituting the liquid crystal display device is also progressing. For example, in the polarizing plate of a liquid crystal display device, the protective film bonded to the surface of a polarizer is becoming thinner. However, when the protective film becomes thin, external moisture easily passes through the protective film and reaches the polarizer, and the polarizer is deteriorated by moisture. As a result, the polarization performance of the polarizer is degraded.

  In order to suppress such polarizer deterioration, a protective film in which a low moisture-permeable cured layer (low moisture-permeable layer, barrier layer) is provided on a substrate has been proposed. For example, in Patent Document 1, a functional film having low moisture permeability is realized by forming a cured layer containing a compound having a specific alicyclic structure on a transparent film substrate. Further, in Patent Document 2, by forming a layer of a compound having a cyclic aliphatic hydrocarbon group and having three or more ethylenically unsaturated double bond groups in the molecule on a transparent support, A low moisture permeability hard coat film is realized.

JP 2006-83225 A (see claim 1, paragraphs [0005], [0007], [0013], etc.) JP 2014-95890 A (see claim 1, paragraphs [0006], [0007], [0031], etc.)

  However, as in Patent Documents 1 and 2, in the configuration in which the low moisture permeable layer is directly provided on the base material, external force (for example, bending stress due to the curved surface of the liquid crystal display device or external impact) is applied to the low moisture permeable layer. It was found that the low moisture-permeable layer was easily cracked when added, and the hardness was not sufficient. The reason is presumed as follows.

  When the low moisture-permeable layer is directly provided on the base material, when the base material and the polarizer are bonded with water paste, the water content of the water paste tends to stay in the base material (from the low moisture-permeable layer to the outside). ) When moisture accumulates on the base material, deformation (dimensional change) of the base material increases, and a load due to stress (for example, tensile stress) is generated in the low moisture-permeable layer on the base material. When an external force is applied to the low moisture permeable layer in such a state that the load is applied, the low moisture permeable layer is easily cracked. In particular, when the substrate is composed of a cellulose resin film having a high moisture permeability, the deformation of the substrate due to water content becomes larger, and the load on the low moisture permeable layer also becomes larger. Cracks are more likely to occur. In addition, it is considered that the low moisture permeable layer is likely to be broken by an external force because the layer density is high, which causes the layer to become brittle.

  Furthermore, in order to reduce crosstalk during observation with polarized glasses or the like, when the base material on which the low moisture permeable layer is formed is composed of a λ / 4 film, a phase difference variation due to water content occurs in the λ / 4 film. . For this reason, it was also found that the crosstalk caused by the above-described phase difference variation occurred when observing an image using polarized glasses or the like, and the visibility was lowered.

  The present invention has been made to solve the above-described problems, and has an object of including a film substrate made of a cellulose-based resin and functioning as a λ / 4 film, and a low moisture-permeable cured layer. Even with this configuration, it is possible to reduce the cracking of the hardened layer due to external force and suppress the fluctuation of the phase difference due to the moisture content of the film substrate, thereby avoiding a decrease in visibility during image observation using polarized glasses or the like. An optical film, a polarizing plate having the optical film, and an image display device having the polarizing plate are provided.

  The inventors of the present application provide a buffer layer between a film substrate as a λ / 4 film made of a cellulose-based resin and a low moisture-permeable cured layer, and contains specific fine particles in the buffer layer and the cured layer. The inventors have found that the above problems can be solved, and have reached the present invention. That is, the above object of the present invention is achieved by the following configuration.

1. A film substrate as a λ / 4 film made of a cellulose-based resin;
A cured layer containing a resin having an alicyclic structure and fine particles coated with a polymer silane coupling agent;
Having a buffer layer formed between the film substrate and the cured layer;
The said buffer layer contains resin different from the said resin of the said hardening layer, and the microparticles | fine-particles coat | covered with the polymer silane coupling agent, The optical film characterized by the above-mentioned.

  2. 2. The optical film as described in 1 above, wherein the resin of the buffer layer is a urethane acrylate resin.

3. 3. The optical film as described in 1 or 2 above, wherein in the buffer layer, the following reaction rate T of the resin obtained based on IR spectrum measurement is 20% or more and 40% or less.
T (%) = {(A−B) / A} × 100
However,
A is before curing of the resin of the buffer layer, a carbon - infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, a carbon - infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond The ratio of
B is after curing of the resin of the buffer layer, a carbon - infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, a carbon - infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond The ratio of

  4). The ratio a / b between the content a (parts by mass) of the fine particles contained in the cured layer and the content b (parts by mass) of the fine particles contained in the buffer layer is 2 or more and 10 or less. 4. The optical film as described in any one of 1 to 3 above.

5. The optical film according to any one of 1 to 4 and a polarizer,
The polarizing plate, wherein the film base of the optical film is bonded to one surface of the polarizer with water glue.

  6). 6. An image display device, wherein the polarizing plate according to 5 is provided on at least one surface side of the display cell.

  By the above-mentioned means of the present invention, the crack of the hardened layer due to external force is reduced even in a configuration comprising a film base material made of a cellulose-based resin and functioning as a λ / 4 film and a low moisture-permeable hardened layer. In addition, an optical film that can suppress a change in retardation due to water content of the film base material and can avoid a decrease in visibility during image observation using polarized glasses, a polarizing plate having the optical film, and the polarization It is possible to provide an image display device having a plate.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  When the cured layer contains a resin having an alicyclic structure, a low moisture-permeable cured layer (low moisture-permeable layer) is realized. This hardened layer is formed (laminated) via a buffer layer on a film substrate as a λ / 4 film. At this time, since the buffer layer contains the fine particles, even if moisture enters from the opposite side of the cured layer to the film substrate made of the cellulose-based resin, the moisture is transferred from the film substrate to the buffer layer. It is presumed that it was able to escape (because the fine particles absorb the moisture). Thereby, it can suppress that a film base material deform | transforms with moisture, and it thinks that it was able to reduce that a load was applied to a hardened layer by the deformation. In addition, since the buffer layer contains a resin different from the resin of the cured layer that realizes low moisture permeability, even when an external impact is applied to the cured layer formed on the buffer layer, It is considered that the shock was relaxed (absorbed) by the buffer layer. Furthermore, the hardness of a hardened layer can be raised by containing the said microparticles | fine-particles also in a hardened layer.

  In this way, it is possible to reduce the load of the hardened layer by suppressing deformation due to water content of the film base, the shock absorbing property of the buffer layer, and the hardness of the hardened layer to be increased. Even when stress or impact is applied, the hardened layer is difficult to break, and cracking of the hardened layer can be reduced.

  In addition, since the water content of the λ / 4 film can be suppressed, variation in retardation due to the water content of the λ / 4 film can be suppressed. As a result, it is possible to reduce the occurrence of crosstalk due to the phase difference variation of the λ / 4 film during image observation using polarized glasses or the like, and avoid a reduction in visibility.

It is sectional drawing which decomposes | disassembles and shows the structure of the outline of the image display apparatus which concerns on embodiment of this invention.

  An embodiment of the present invention will be described below with reference to the drawings. In the present specification, when the numerical range is expressed as A to B, the numerical value range includes the values of the lower limit A and the upper limit B. The present invention is not limited to the following contents.

  In order to solve the above-described problems, the present inventors have studied an optical film having the following configuration. That is, the optical film of the present embodiment includes a film substrate as a λ / 4 film made of a cellulose resin, a cured layer, and a buffer layer. The cured layer includes a resin having an alicyclic structure and fine particles formed by coating with a polymer silane coupling agent. The buffer layer is formed between the film substrate and the cured layer, and includes a resin different from the resin of the cured layer and fine particles coated with a polymer silane coupling agent. This feature is a technical feature common to the invention according to each claim described in the claims.

  When the cured layer contains a resin having an alicyclic structure, a low moisture-permeable cured layer (low moisture-permeable layer) is realized. This hardened layer is formed on a film substrate as a λ / 4 film made of a cellulose resin via a buffer layer. That is, a buffer layer is interposed between the cured layer and the film substrate. This buffer layer includes fine particles coated with a polymer silane coupling agent. Since the fine particles have hygroscopicity (water absorption), for example, when the optical film is used as a protective film and bonded to one side of the polarizer with water paste, the water paste moisture enters the film substrate. However, the moisture escapes from the film substrate to the buffer layer due to the hygroscopicity of the buffer layer (the fine particles). Thereby, it can suppress that a film base material deform | transforms <expansion by water | moisture content, and it can reduce that the tensile stress is provided to a hardened layer by the deformation | transformation, and the load by the stress arises.

  In addition, since the buffer layer contains a resin (for example, urethane acrylate resin is preferable) different from the resin of the cured layer that achieves low moisture permeability, the cured layer formed on the buffer layer has an external Even when an impact is applied, the impact can be relaxed (absorbed) by the buffer layer. Furthermore, the hardness of a hardened layer can be raised by containing the microparticles | fine-particles coat | covered with a polymer silane coupling agent also in a hardened layer. In the cured layer, low moisture permeability is realized by the resin having an alicyclic structure. Therefore, even if the cured layer contains the fine particles having hygroscopicity, a cured layer having low moisture permeability can be realized. .

  In this way, the film substrate is prevented from being deformed by moisture, and the shock absorbing layer absorbs the shock. The hardness of the cured layer is ensured to some extent, so that the external force applied to the cured layer (for example, bending due to the curved surface of the liquid crystal display device). Even when stress or impact from the outside is applied, the hardened layer is difficult to break. Therefore, even if it is the structure which provides the low moisture-permeable cured layer, the crack of a cured layer can be reduced.

  In addition, since the water content of the λ / 4 film can be suppressed, variation in retardation due to the water content of the λ / 4 film can be suppressed. As a result, it is possible to reduce the occurrence of crosstalk due to the phase difference variation of the λ / 4 film during image observation using polarized glasses or the like, and avoid a reduction in visibility.

  Moreover, it is desirable that the resin of the buffer layer (resin different from the resin of the cured layer) is a urethane acrylate resin. When the lower buffer layer is soft, it is difficult to obtain high hardness as the optical film. Urethane acrylate resin can form a relatively hard buffer layer when using fine particles coated with a polymer silane coupling agent, and by forming a hardened layer on it, the hardness of the optical film is easy. It becomes possible to raise.

In the above buffer layer, the following reaction rate T of the resin obtained based on IR spectrum (Infrared Spectroscopy) measurement is desirably 20% or more and 40% or less.
T (%) = {(A−B) / A} × 100
However,
A corresponds to an infrared absorption intensity of 810 cm ⁻¹ corresponding to a carbon-carbon double bond and a carbon-oxygen double bond before curing of the resin of the buffer layer (resin in which the solvent was volatilized from the coating solution). Shows the ratio to the infrared absorption intensity of 1725 cm ⁻¹ ,
B is after curing of the resin of the buffer layer, a carbon - the infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond - the infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, carbon Indicates the ratio.

  The reaction rate T obtained based on the IR spectrum measurement corresponds to the hardness of the buffer layer and the hardened layer. That is, the smaller the value of T, the softer each layer (the resin does not proceed with curing), and the larger the T value, the harder each layer (the curing of the resin proceeds). When the reaction rate T of the resin in the buffer layer is 20% or more and 40% or less, an appropriate hardness can be given to the buffer layer, an appropriate hardness can be given to the cured layer thereon, and an external force is applied. Sometimes the hardened layer can be made more difficult to break.

  That is, if the reaction rate T is 20% or more, the hardness of the resin is high (because the buffer layer is not too soft), so the hardened layer formed on the buffer layer is hardened, and the hardness of the entire optical film Can be increased (hardened). On the other hand, if the reaction rate T is 40% or less, the buffer layer has buffer properties (impact absorbability), and even when an external force is applied, the hardened layer is difficult to break.

  Content a (part by mass) of fine particles coated with a polymer silane coupling agent contained in the cured layer and content b (mass of fine particles coated with a polymer silane coupling agent contained in the buffer layer The ratio a / b with respect to (part) is preferably 2 or more and 10 or less. By setting the content (ratio) of the fine particles in the hardened layer and the buffer layer within the above range, the buffer layer has appropriate buffering properties, and the hardened layer has appropriate hardness, and is cured by external force. Layer cracking can be reduced.

  That is, when the ratio a / b is 2 or more, the content b of the fine particles in the buffer layer decreases, the buffer layer does not become too hard, the buffer layer has high buffering properties, and the hardened layer is difficult to break. On the other hand, if the ratio a / b is 10 or less, the content a of the fine particles in the cured layer is reduced, the cured layer itself is not easily brittle, and when an external force is applied, the cured layer is not easily broken.

  The polarizing plate of one embodiment of the present application includes the above-described optical film of the present embodiment and a polarizer, and the film base material of the optical film is bonded to one surface of the polarizer with water glue. It is configured.

  As described above, when the optical film includes the buffer layer, the moisture of the water paste can be released from the film base material to the buffer layer, and the water content of the film base material can be suppressed. Thereby, it is possible to suppress the phase difference variation due to the water content of the film substrate functioning as a λ / 4 film. Therefore, an image display device is configured using the polarizing plate, and an image is displayed on the image display device. Thus, when an image is observed using polarized glasses or the like, it is possible to reduce the occurrence of crosstalk due to the phase difference fluctuation of the film base material, and to avoid a decrease in visibility.

  The image display device of one embodiment of the present application has a configuration in which the polarizing plate of the present embodiment described above is provided on at least one surface side of the display cell. Thereby, even when an observer observes a display image using polarized glasses or the like, the observer can observe a bright image in which crosstalk due to phase difference fluctuation of the film substrate is reduced.

  Hereinafter, a specific configuration of the image display device to which the optical film of the present embodiment is applied will be described.

[Configuration of image display device]
FIG. 1 is an exploded sectional view showing a schematic configuration of an image display device 1 according to an embodiment of the present application. The image display device 1 is, for example, a liquid crystal display device, and is configured by bonding a protective portion 3 to a polarizing plate 5 (particularly on an optical film 16 described later) of the liquid crystal display panel 2 via a filling layer 31. Yes. The filling layer 31 is an adhesive layer (void filler) made of a photocurable resin such as acrylic, and is formed on the entire surface of the polarizing plate 5 of the liquid crystal display panel 2. The protection unit 3 protects the surface of the liquid crystal display panel 2 and is formed of a front plate made of acrylic resin or glass, for example. Note that a touch panel (such as a capacitance method or a resistance film method) may be used as the protection unit 3 instead of the front plate.

  The liquid crystal display panel 2 is configured by disposing polarizing plates 5 and 6 on both sides of a liquid crystal cell 4 (display cell) in which a liquid crystal layer is sandwiched between a pair of substrates. The polarizing plate 5 is attached to one surface side (for example, the viewing side) of the liquid crystal cell 4 via the adhesive layer 7. The polarizing plate 6 is attached to the other surface side (for example, the backlight 9 side) of the liquid crystal cell 4 through the adhesive layer 8. The driving method of the liquid crystal display panel 2 is not particularly limited, and various driving methods such as an IPS (In Plane Switching) method, a TN (Twisted Nematic) method, and a VA (Virtical Alignment) method can be employed.

  The polarizing plate 5 includes a polarizer 11 that transmits predetermined linearly polarized light, a film substrate 12, a buffer layer 13, a cured layer 14, and a liquid crystal cell of the polarizer 11 that are sequentially stacked on the protective unit 3 side of the polarizer 11. It is comprised with the optical film 15 laminated | stacked on the 4 side. The film base material 12, the buffer layer 13, and the hardened layer 14 constitute an optical film 16 as a protective film formed on the viewing side surface of the polarizer 11. The film substrate 12 is made of a cellulose-based resin (cellulose ester-based resin) and is also referred to as a cellulose ester film substrate. The surface of the polarizing plate 5 can be protected by providing the cured layer 14 on the film substrate 12 via the buffer layer 13.

  The film substrate 12 is bonded with the polarizer 11 and water paste, and the film thickness is preferably in the range of 5 to 50 μm, for example. By making the film substrate 12 thinner, the optical film 16 and the polarizing plate 5 can be made thinner, which can contribute to reducing the thickness of the entire image display device 1.

  The film substrate 12 is composed of a λ / 4 film. The λ / 4 film is a layer that imparts in-plane retardation of about ¼ of the wavelength to transmitted light, and in the present embodiment, the λ / 4 film is composed of a film that is obliquely stretched. The angle (crossing angle) formed between the slow axis of the λ / 4 film and the absorption axis of the polarizer 11 is 30 ° to 60 °, whereby the linearly polarized light from the polarizer 11 is converted into the λ / 4 film ( It is converted into circularly polarized light or elliptically polarized light by the film substrate 12).

  Therefore, when an observer wears polarized sunglasses and observes a display image, the polarizing plate can be used regardless of how the transmission axis of the polarizer 11 (perpendicular to the absorption axis) and the transmission axis of the polarized sunglasses are misaligned. The light component parallel to the transmission axis of the polarized sunglasses contained in the light emitted from 5 (circularly polarized light or elliptically polarized light) can be guided to the eyes of the observer. Thereby, it can suppress that it becomes difficult to see a display image with the angle to observe. In addition, even when the observer does not wear polarized sunglasses, since it is circularly polarized light or elliptically polarized light that is emitted from the polarizing plate 5 and incident on the observer's eyes, linearly polarized light is directly incident on the observer's eyes. Compared to the above, the burden on the eyes of the observer can be reduced. In addition, when observing a display image using polarized glasses instead of polarized sunglasses in order to observe a stereoscopic image, it is possible to suppress the display image from becoming difficult to see depending on the viewing angle for the same reason as described above. it can.

  The cured layer 14 includes a resin having an alicyclic structure and fine particles coated with a polymer silane coupling agent. Although details of the resin will be described later, a cured layer 14 (low moisture permeable layer, barrier layer) having low moisture permeability can be realized by including the resin in the cured layer 14. Moreover, moderate hardness can be provided to the hardened layer 14 because the hardened layer 14 contains the said microparticles | fine-particles. Thereby, the damage of the surface of the optical film 16 can be suppressed.

  The buffer layer 13 is formed between the film substrate 12 and the cured layer 14, and is a resin (for example, urethane acrylate resin) different from the resin (resin having an alicyclic structure) constituting the cured layer 14 and a polymer. And fine particles coated with a silane coupling agent. Since the fine particles have hygroscopicity, even if the moisture of the water paste for bonding enters the film substrate 12, the moisture escapes from the film substrate 12 to the buffer layer 13 (the buffer layer 13 is the above). To absorb moisture). Thereby, it can reduce that the film base material 12 deform | transforms with moisture and the load by stress arises in the hardened layer 14. FIG. In addition, even when an external impact is applied to the hardened layer 14, the buffer layer 13 has a buffering property that reduces (absorbs) the shock, so that the hardened layer 14 is difficult to break.

  As the resin for the buffer layer 13, it is desirable to use a urethane acrylate resin from the viewpoint of hardness. In addition, from the viewpoint of giving appropriate hardness to the buffer layer 13, the reaction rate T (defined as described above) of the resin of the buffer layer 13 is desirably 20% or more and 40% or less. Further, from the viewpoint of giving the buffer layer 13 moderate buffering, the ratio a / b between the content a of the fine particles in the cured layer 14 and the content b of the fine particles in the buffer layer 13 is 2 or more and 10 or less. It is desirable that

  Further, the resin (resin having an alicyclic structure) contained in the cured layer 14 and the fine particles have poor compatibility. For this reason, when the hardened layer 14 is directly provided on the film substrate 12, the fine particles are easily aggregated by reacting with an extract (for example, an additive) from the film base 12, and the fine particle layer becomes a hardened layer 14. It becomes easy to form separately in the inside. When the fine particle layer is formed, the reflected light of the external light on the surface of the hardened layer 14 interferes with the reflected light of the external light on the fine particle layer, and unevenness occurs during black display.

  On the other hand, when the buffer layer 13 is provided between the film substrate 12 and the cured layer 14 as in this embodiment, the presence of the buffer layer 13 causes the fine particles contained in the cured layer 14 to be separated from the film substrate 12. It becomes difficult to react with the extract of the above, and the fine particles are less likely to aggregate. Accordingly, the fine particle layer is hardly formed, and the above-described display unevenness due to the formation of the layer can be reduced.

  When the buffer layer 13 does not contain the fine particles, a refractive index difference is generated between the cured layer 14 and the buffer layer 13 depending on the presence or absence of the fine particles, and light interference occurs due to the refractive index difference. However, in this embodiment, since the buffer layer 13 also includes the same fine particles as the fine particles contained in the hardened layer 14, the refractive index difference between the hardened layer 14 and the buffer layer 13 can be reduced, and the above refractive index. Light interference caused by the difference can be reduced.

  The optical film 15 is provided to protect the back surface of the polarizing plate 5. The optical film 15 may be made of the same material as the film substrate 12 (for example, cellulose ester), or may be made of other materials. Moreover, the optical film 15 may be comprised with the film (retardation film) which has an optical compensation function, and may be comprised with the zero phase difference film which provides almost no phase difference with respect to transmitted light.

  The polarizing plate 6 includes a polarizer 21 that transmits predetermined linearly polarized light, an optical film 22 that is disposed on the liquid crystal cell 4 side of the polarizer 21, and an optical that is disposed on the opposite side of the polarizer 21 from the liquid crystal cell 4. The film 23 is laminated. The polarizer 21 is disposed so that the transmission axis is perpendicular to the polarizer 11 (crossed Nicol state). The optical films 22 and 23 are provided to protect the front and back surfaces of the polarizing plate 6, but they may be made of the same material (for example, cellulose ester) as the film substrate 12 of the polarizing plate 5. However, it may be composed of other materials.

  In addition, the above-described optical film 16 can be used for applications other than the polarizing plate. In this case, the cured layer 14 may be provided on both surfaces of the film substrate 12. Therefore, in the optical film 16, it can be said that the cured layer 14 may be formed on at least one surface of the film substrate 12. Further, the image display device 1 can be configured by arranging two polarizing plates 5 on both sides of the liquid crystal cell 4.

[Optical film]
Hereinafter, the detail of the optical film 16 mentioned above is demonstrated.

<Hardened layer>
The cured layer of this embodiment contains an active energy ray-curable resin having an alicyclic structure (hereinafter also simply referred to as a curable resin). Specific examples of the alicyclic structure include norbornyl, tricyclodecanyl, tetracyclododecanyl, pentacyclopentadecanyl, adamantyl, diamantanyl and the like.

  An active energy ray is defined as an energy ray capable of decomposing a compound (photopolymerization initiator) that generates active species to generate active species. Examples of such active energy rays include light energy rays such as visible light, ultraviolet rays (UV), electron beams (EB), infrared rays, X rays, α rays, β rays, and γ rays. However, it is preferable to use ultraviolet rays because it has a certain energy level, has a high curing rate, is relatively inexpensive, and is compact.

The active energy ray curable resin preferably has an ethylenically unsaturated double bond. Examples of the ethylenically unsaturated double bond group include polymerizable functional groups such as (meth) acryloyl group, vinyl group, styryl group, and allyl group. Among them, (meth) acryloyl group and —C (O) OCH═ CH ₂ is preferred.

  The active energy ray-curable resin having an alicyclic structure is preferably composed of a hydrocarbon group having an alicyclic structure and a group having an ethylenically unsaturated double bond bonded via a linking group. Examples of the linking group include a single bond, an alkylene group, an amide group, a carbamoyl group, an ester group, an oxycarbonyl group, an ether group, or a group obtained by combining these. Specifically, polyols such as diols and triols having an alicyclic structure, carboxylic acids having (meth) acryloyl groups, vinyl groups, styryl groups, allyl groups, carboxylic acid derivatives, epoxy derivatives, isocyanate derivative compounds, etc. Can be easily synthesized by a one-step or two-step reaction.

  Hereinafter, specific compounds of the active energy ray-curable resin having an alicyclic structure are represented by the following general formulas (I) to (VII), but the present invention is not limited thereto.

（式中、Ｒ１は水素原子または炭素数１〜３のアルキル基、Ｒ２は炭素数１〜５のアルキレン基またはアルキレンオキサイド基、Ｒ３は水素原子または炭素数１〜３のアルキル基、ｎは１または２の整数。）

Wherein R1 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R2 is an alkylene group or alkylene oxide group having 1 to 5 carbon atoms, R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and n is 1 Or an integer of 2.)

（式中、Ｒ１、Ｒ３およびｎは、上記一般式（Ｉ）と同じ意味である。）

(Wherein R1, R3 and n have the same meaning as in the general formula (I)).

  In general formula (I) and general formula (II), R1 represents a hydrogen atom or a C1-C3 alkyl group, Preferably, a hydrogen atom, a methyl group, and an ethyl group are represented. R2 represents an alkylene group having 1 to 5 carbon atoms or an alkylene oxide group, and preferably represents a methylene group, an ethylene group, a methylene oxide group, or an ethylene oxide group. R3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and preferably represents a hydrogen atom, a methyl group, or an ethyl group.

  Hereinafter, although the preferable specific example of a compound represented by general formula (I) is shown, this invention is not limited to these.

  Hereinafter, although the preferable specific example of a compound represented by general formula (II) is shown, this invention is not limited to these.

  Examples of commercially available compounds represented by the general formulas (I) and (II) include NK ester A-DCP (tricyclodecane dimethanol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.). However, it is not limited to these.

一般式（III）中、Ｌ及びＬ’は各々独立に二価以上の連結基を表し、同時に二価とはならない。ｎは１〜３の整数を表す。

In general formula (III), L and L ′ each independently represent a divalent or higher valent linking group and are not divalent simultaneously. n represents an integer of 1 to 3.

一般式（IV）中、Ｌ及びＬ’は各々独立に二価以上の連結基を表し、同時に二価とはならない。ｎは１〜２の整数を表す。

In general formula (IV), L and L ′ each independently represent a divalent or higher valent linking group and are not divalent simultaneously. n represents an integer of 1 to 2.

一般式（Ｖ）中、Ｌ及びＬ’は各々独立に二価以上の連結基を表し、同時に二価とはならない。ｎは１〜２の整数を表す。

In general formula (V), L and L ′ each independently represent a divalent or higher valent linking group and are not divalent simultaneously. n represents an integer of 1 to 2.

一般式（VI）中、Ｌ、Ｌ’及びＬ’’は各々独立に二価以上の連結基を表す。

In general formula (VI), L, L ′, and L ″ each independently represent a divalent or higher linking group.

一般式（VII）中、Ｌ及びＬ’は各々独立に二価以上の連結基を表し、同時に二価とはならない。

In general formula (VII), L and L ′ each independently represent a divalent or higher linking group and are not divalent simultaneously.

  Specific examples of the compounds represented by the general formulas (III) to (VII) are shown below, but are not limited thereto.

  It is preferable that a hardened layer contains 30 mass% or more of active energy ray-curable resins which have an alicyclic structure, More preferably, it is 50 mass% or more.

(Photopolymerization initiator)
The cured layer preferably contains a photopolymerization initiator to accelerate the curing of the actinic radiation curable resin. The content of the photopolymerization initiator is preferably such that the photopolymerization initiator: active ray curable resin = 20: 100 to 0.01: 100 in terms of mass ratio. Specific examples of the photopolymerization initiator include alkylphenone series, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto. It is not something. Commercially available products may be used as the photopolymerization initiator, and preferred examples include Irgacure 184, Irgacure 907, and Irgacure 651 manufactured by BASF Japan.

(Fine particles)
The hardened layer may contain fine particles. Although it does not restrict | limit especially as microparticles | fine-particles, A silica, an alumina, a zirconia, a titanium oxide, an antimony pentoxide etc. are mentioned, Preferably it is a silica. The silica fine particles may be hollow particles having cavities inside. Among these, fine particles coated with a polymer silane coupling agent are particularly preferable because they give an appropriate hardness to the cured layer and exhibit good mechanical properties. About content, content used as microparticles | fine-particles: active ray curable resin = 0.1: 100-400: 100 is preferable.

(Polymer silane coupling agent)
The polymer silane coupling agent refers to a reaction product of a polymerizable monomer and a silane coupling agent (reactive silane compound). Such a polymer silane coupling agent can be obtained, for example, according to the method for producing a reaction product of a polymerizable monomer and a reactive silane compound disclosed in JP-A-11-116240.

  Specific examples of the polymerizable monomer include (meth) acrylic acid, (meth) methyl acrylate, (meth) ethyl acrylate, (meth) acrylic acid-n-propyl, (meth) acrylic acid isopropyl, (meth) -N-butyl, isobutyl (meth) acrylate, (meth) acrylic acid-n-hexyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid-n-heptyl, (meth) acrylic acid-n-octyl, ( 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, toluyl (meth) acrylate, benzyl (meth) acrylate , (Meth) acrylic acid-2-methoxyethyl, (meth) acrylic acid-3-methoxybutyl, (meth) acrylic acid-2 Hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, stearyl (meth) acrylate, glycidyl (meth) acrylate, 2-aminoethyl (meth) acrylate, ethylene oxide adduct of (meth) acrylic acid, ( Trifluoromethylmethyl (meth) acrylate, 2-trifluoromethylethyl (meth) acrylate, 2-perfluoroethylethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate , 2-perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, diverfluoromethyl methyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethyl methyl (meth) acrylate, ( (Meth) acrylic acid 2-perfluorohexylethyl, (Meth) acrylic acid monomers such as 2-perfluorodecylethyl (meth) acrylate and 2-perfluorohexadecylethyl (meth) acrylate; styrene, vinyltoluene, α-methylstyrene, chlorostyrene, styrenesulfonic acid and the like Styrene monomers such as salts; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene, and vinylidene fluoride; silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; maleic anhydride, maleic acid, malein Monoalkyl and dialkyl esters of acids; fumaric acid, monoalkyl and dialkyl esters of fumaric acid; maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmale Nitrile group-containing vinyl monomers such as amide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, cyclohexylmaleimide; amide group-containing vinyl monomers such as acrylamide and methacrylamide; vinyl acetate, vinyl propionate, vinyl pivalate, benzoate Vinyl esters such as vinyl acid and vinyl cinnamate; Alkenes such as ethylene and propylene; Conjugated dienes such as butadiene and isoprene; Vinyl chloride, vinylidene chloride, allyl chloride, allyl alcohol, acrylic resin monomers; Pentaerythritol triacrylate , Pentaerythritol tetraacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetraacrylate, ditrimethylolpropante La (meth) acrylate, dipentaerythritol hexaacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl acrylate, n-stearyl acrylate, 1,6 -Hexanediol dimethacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, urethane acrylate and the like, and mixtures thereof.

As the reactive silane compound, an organosilicon compound represented by the following formula (1) is preferably used.
X-R-Si (OR) ₃ (1)
(In the formula, R represents an organic group having 1 to 10 carbon atoms selected from a substituted or unsubstituted hydrocarbon group. X represents a (meth) acryloyl group, an epoxy group (glycid group), a urethane group, an amino group, One or more functional groups selected from fluoro groups.)

  Specific examples of the organosilicon compound represented by the formula (1) include 3,3,3-trifluoropropyltrimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxymethyltrimethoxysilane, γ-glycidoxymethyltriethoxysilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- (β-glycidoxyethoxy) Propyltrimethoxysilane, γ- (meth) acrylooxymethyltrimethoxysilane , Γ- (meth) acrylooxymethyltrioxysilane, γ- (meth) acrylooxyethyltrimethoxysilane, γ- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropyl Trimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, 3-ureidoisopropylpropyltriethoxy Silane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctylethyltriisopropoxysilane, trifluoropropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and the like, and mixtures thereof.

  A polymeric silane coupling agent is prepared by reacting a polymerizable monomer with a reactive silane compound. Specifically, an organic solvent solution in which a reactive silane compound is mixed in an amount of 0.5 to 20 parts by weight and further 1 to 10 parts by weight with respect to 100 parts by weight of the polymerizable monomer is prepared, and polymerization is started. It can be obtained by adding an agent and heating.

(Method for preparing polymer silane coupling agent coated fine particles)
Specifically, the polymer silane coupling agent-coated fine particles can be prepared by adding a polymer silane coupling agent to a fine particle organic solvent dispersion and coating the fine particles with the polymer silane coupling agent in the presence of an alkali. The range of the average particle diameter of the obtained polymer silane coupling agent-coated fine particles is preferably 5 to 500 nm, and more preferably 10 to 200 nm, from the viewpoint of securing optical properties when used for an optical film.

  The content of the polymer silane coupling agent-coated fine particles in the cured layer is preferably 0.5 to 80 parts by mass, more preferably 1 to 60 parts by mass as the solid content, from the viewpoint of securing the film strength of the cured layer. .

(Conductive agent)
The hardened layer may contain a conductive agent in order to impart antistatic properties. Preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound.

(Additive)
The cured layer may contain a fluorine-siloxane graft compound, a fluorine-based compound, a silicone-based compound, or a compound having an HLB value of 3 to 18 from the viewpoint of improving coatability. The hydrophilicity can be easily controlled by adjusting the types and amounts of these additives. The HLB value is Hydrophile-Lipophile-Balance, that is, a hydrophilic-lipophilic balance, and is a value indicating the hydrophilicity or lipophilicity of a compound. The smaller the HLB value, the higher the lipophilicity, and the higher the value, the higher the hydrophilicity. The HLB value can be obtained by the following calculation formula.
HLB = 7 + 11.7Log (Mw / Mo)
In the formula, Mw represents the molecular weight of the hydrophilic group, Mo represents the molecular weight of the lipophilic group, and Mw + Mo = M (molecular weight of the compound). Alternatively, according to the Griffin method, HLB value = 20 × total formula weight of hydrophilic part / molecular weight (J. Soc. Cosmetic Chem., 5 (1954), 294) and the like.

  Specific examples of the compound having an HLB value of 3 to 18 are listed below, but are not limited thereto. Figures in parentheses indicate HLB values. Made by Kao Corporation: Emulgen 102KG (6.3), Emulgen 103 (8.1), Emulgen 104P (9.6), Emulgen 105 (9.7), Emulgen 106 (10.5), Emulgen 108 (12. 1), Emulgen 109P (13.6), Emulgen 120 (15.3), Emulgen 123P (16.9), Emulgen 147 (16.3), Emulgen 210P (10.7), Emulgen 220 (14.2) , Emulgen 306P (9.4), Emulgen 320P (13.9), Emulgen 404 (8.8), Emulgen 408 (10.0), Emulgen 409PV (12.0), Emulgen 420 (13.6), Emulgen 430 (16.2), Emulgen 705 (10.5), Emulgen 707 (12.1), Emulgen 7 9 (13.3), Emulgen 1108 (13.5), Emulgen 1118S-70 (16.4), Emulgen 1135S-70 (17.9), Emulgen 2020G-HA (13.0), Emulgen 2025G (15. 7), Emulgen LS-106 (12.5), Emulgen LS-110 (13.4), Emulgen LS-114 (14.0), manufactured by Nissin Chemical Industry Co., Ltd .: Surfynol 104E (4), Surfynol 104H (4), Surfinol 104A (4), Surfinol 104BC (4), Surfinol 104DPM (4), Surfinol 104PA (4), Surfinol 104PG-50 (4), Surfinol 104S (4), Surfi Knoll 420 (4), Surfynol 440 (8), Surfynol 46 (13), Surfynol 485 (17), Surfynol SE (6), Shin-Etsu Chemical Co., Ltd.: X-22-4272 (7), X-22-6266 (8).

  The fluorine-siloxane graft compound refers to a compound of a copolymer obtained by grafting polysiloxane and / or organopolysiloxane containing siloxane and / or organosiloxane alone on at least a fluorine-based resin. Such a fluorine-siloxane graft compound can be prepared by a method as described in Examples described later. Or as a commercial item, Fuji Chemical Industries Ltd. ZX-022H, ZX-007C, ZX-049, ZX-047-D etc. can be mentioned.

  Examples of the fluorine-based compound include Megafac series (F-477, F-487, F-569, etc.) manufactured by DIC Corporation, OPTOOL DSX, OPTOOL DAC, etc. manufactured by Daikin Industries, Ltd.

  As the silicone-based compound, manufactured by Shin-Etsu Chemical Co., Ltd .: KF-351, KF-352, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-618, KF-6011, KF -6015, KF-6004, manufactured by Big Chemie Japan Co., Ltd .: BYK-UV3576, BYK-UV3535, BYK-UV3510, BYK-UV3505, BYK-UV3500, BYK-UV3510, and the like. These components are preferably added in a range of 0.005 parts by mass or more and 10 parts by mass or less with respect to the solid component in the cured layer composition. Two or more kinds of these components may be added as long as the total additive amount is in the range of 0.005 parts by mass or more and 10 parts by mass or less.

(UV absorber)
The hardened layer may contain an ultraviolet absorber described in the cellulose ester film described later. As content of a ultraviolet absorber, it is preferable that it is content which becomes ultraviolet absorber: curable resin = 0.01: 100-20: 100 by mass ratio.

(solvent)
The cured layer is preferably provided by diluting the above-mentioned components forming the cured layer with a solvent to obtain a cured layer composition, which is applied onto a film substrate by the following method, dried and cured.

  Solvents include ketones (methyl ethyl ketone, acetone, etc.) and / or acetate esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (ethanol, methanol, normal propanol, isopropanol), propylene glycol monomethyl ether, cyclohexanone, methyl isobutyl ketone. Etc. are preferable. The coating amount of the cured layer composition is suitably an amount that results in a wet film thickness of 0.1 to 80 μm, and preferably an amount that results in a wet film thickness of 0.5 to 30 μm. Moreover, as a dry film thickness, it is the range of an average film thickness of 0.01-20 micrometers, Preferably it is the range of 1-15 micrometers. More preferably, it is the range of 2-12 micrometers.

  As a method for applying the cured layer composition, known methods such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, and an ink jet method can be used.

(Method for forming cured layer)
A cured layer composition may be applied onto a buffer layer, which will be described later, and then dried and cured (irradiated with active rays (also referred to as UV curing treatment)), and if necessary, heat treatment may be performed after UV curing. The heat treatment temperature after UV curing is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 120 ° C. or higher. By performing the heat treatment after UV curing at such a high temperature, a cured layer having excellent film strength can be obtained.

  Generally, it is known that the drying process changes from a constant state to a gradually decreasing state when drying starts. A section in which the drying speed is constant is called a constant rate drying section, and a section in which the drying speed decreases is called a decreasing rate drying section.

  Drying is preferably performed at a temperature of 30 ° C. or higher in the drying section. More preferably, the temperature in the drying section is 50 ° C. or higher.

  As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

The irradiation conditions vary depending on individual lamps, irradiation of actinic rays is generally within the range of 50~1000mJ / cm ^2, preferably in the range of 50 to 300 mJ / cm ^2. In the UV curing treatment, oxygen removal (for example, replacement with an inert gas such as nitrogen purge) can be performed to prevent reaction inhibition by oxygen. The cured state of the surface can be controlled by adjusting the removal amount of the oxygen concentration.

  When irradiating actinic radiation, it is preferably performed while applying tension in the film transport direction, and more preferably while applying tension in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the conveying direction on the back roller, or tension may be applied in the width direction or biaxial direction by a tenter. Thereby, a film having further excellent flatness can be obtained.

<Buffer layer>
The buffer layer contains a resin different from the resin contained in the cured layer. The buffer layer resin preferably contains an acrylic material. Acrylic materials are synthesized from monofunctional or polyfunctional (meth) acrylate compounds such as (meth) acrylic acid esters of polyhydric alcohols, diisocyanates and polyhydric alcohols, and hydroxy esters of (meth) acrylic acid. Such a polyfunctional urethane (meth) acrylate compound can be used. Besides these, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used.

  In the present embodiment, “(meth) acryl” means both “acryl” and “methacryl”, “(meth) acrylate” means both “acrylate” and “methacrylate”, and “( “Meth) acryloyl” refers to both “acryloyl” and “methacryloyl”. For example, “urethane (meth) acrylate” indicates both “urethane acrylate” and “urethane methacrylate”.

  Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl ( (Meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) ) Acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, benzyl (Meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meta) ) Acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl hydrogen phthalate, 2- (meth) acryloyloxypropyl hydrogen Phthalate, 2- (meth) acryloyloxypropyl hexahydrohydrogen phthalate, 2- (meth) acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate , Hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, 2 -Adamantane derivative mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantanediol.

  Examples of the bifunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and nonanediol di (meth). Acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol Di (meth) acrylate, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Examples of the trifunctional or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxyethyl. 3 such as tri (meth) acrylate such as isocyanurate tri (meth) acrylate and glycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate Functional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra Trifunctional or more polyfunctional (meth) such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate Examples thereof include acrylate compounds and polyfunctional (meth) acrylate compounds in which a part of these (meth) acrylates is substituted with an alkyl group or ε-caprolactone.

  In particular, UV curable acrylate resins, UV curable urethane acrylate resins, UV curable polyester acrylate resins, UV curable epoxy acrylate resins, UV curable polyol acrylate resins, or UV curable epoxy resins are preferred. Among them, an ultraviolet curable acrylate resin is preferable.

  As the ultraviolet curable acrylate resin, a polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate.

  Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule. Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tri / tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, glycerol triacrylate relay , Dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tri Methylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin tri Methacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexamethacrylate, polybasic acid acrylate. A monofunctional acrylate may also be used. Monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl Examples include acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and cyclohexyl acrylate. Such acrylates can be obtained from Nippon Kasei Kogyo Co., Ltd., Shin-Nakamura Chemical Co., Ltd., Osaka Organic Chemical Co., Ltd., etc.

  Among acrylic materials, the desired molecular weight and molecular structure can be designed, the buffer layer can have an appropriate hardness, and the physical properties of the formed buffer layer can be easily balanced. For the reason, polyfunctional urethane acrylate can be preferably used. The urethane acrylate is obtained by reacting a polyhydric alcohol, a polyvalent isocyanate, and a hydroxyl group-containing acrylate.

  The solvent contained in the buffer layer forming composition used for forming the buffer layer is preferably a solvent that dissolves or swells the film substrate. When the solvent dissolves or swells the film substrate, the composition for forming a buffer layer can easily penetrate from the surface of the film substrate to the inside, and the adhesion between the film substrate and the buffer layer can be improved.

  In addition, a layer in which the resin component of the film substrate and the resin component of the buffer layer are mixed is formed near the surface layer of the film substrate, and the refractive index of the film substrate and the buffer layer is inclined by the action of this layer. And the occurrence of uneven interference can be prevented.

  When a cellulose ester-based resin described later is used as the film substrate, examples of the solvent for dissolving or swelling the surface of the film substrate include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1, 4 -Ethers such as dioxane, 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole and phenetole, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone , And ketones such as methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propion brewed ethyl, n-pentyl acetate , And γ- esters such as butyrolactone, further methyl cellosolve, cellosolve, butyl cellosolve, cellosolve such as cellosolve acetate and the like, can be used in combination thereof alone, or two or more kinds. Further, it is preferable to use at least one of methyl acetate, ethyl acetate, methyl ethyl ketone, acetylacetone, acetone, and cyclohexanone.

  The buffer layer desirably contains a photopolymerization initiator. Examples of the photopolymerization initiator include 2,2-ethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler ketone, acetophenone, 2 -Chlorothioxanthone and the like. You may use these individually or in combination of 2 or more types.

  The buffer layer preferably contains a photosensitizer. Examples of the photosensitizer include tertiary amines such as triethylamine, triethanolamine and 2-dimethylaminoethanol, alkylphosphine such as triphenylphosphine, and thioethers such as β-thiodiglycol. These may be used alone or in combination of two or more.

  The buffer layer preferably contains a leveling agent. Among the leveling agents, it is most preferable to use an acrylic leveling agent. By using the leveling agent, it is possible to prevent defects such as film thickness unevenness and coating liquid repellency that may occur when the buffer layer is formed. In addition, by using an acrylic leveling agent, compared to the case of using a fluorine-based or silicone-based leveling agent, recoatability when a cured layer is laminated on the buffer layer, and adhesion between the buffer layer and the cured layer are improved. Deterioration can be prevented.

  Further, quaternary ammonium cations or conductive metal fine particles may be added to the buffer layer to impart conductivity to the buffer layer.

  The coating method for the buffer layer forming composition includes dip coating method, spin coating method, flow coating method, spray coating method, roll coating method, gravure roll coating method, air doctor coating method, plate coating method, wire doctor coating. A method such as a method, a knife coating method, a reverse coating method, a transfer roll coating method, a micro gravure coating method, a kiss coating method, a cast coating method, a slot orifice coating method, a calendar coating method, a die coating method, or the like can be employed. Among these, the microgravure coating method is preferable when a uniform thin film layer is formed, and the die coating method is preferable when a thick film layer needs to be formed.

  The buffer layer contains the same fine particles as those contained in the cured layer, that is, fine particles coated with a polymer silane coupling agent. At this time, the ratio a / b between the content of the fine particles contained in the cured layer and a and the content b of the fine particles contained in the buffer layer may be 1, but 2 or more and 10 or less It is desirable that The reason is as described above.

  In addition, the buffer layer may contain the same additive as the hardened layer in addition to the fine particles. Moreover, a buffer layer can be formed on a film base material by the method similar to the formation method of a hardened layer.

<Back coat layer>
You may provide a backcoat layer in the surface on the opposite side to the side which provided the hardened layer of the optical film. The back coat layer is provided to correct curling caused by providing a hardened layer or other layers by coating or CVD. That is, the degree of curling can be balanced by imparting the property of being rounded with the surface on which the backcoat layer is provided facing inward. In addition, it is also preferable that the back coat layer is preferably applied also as an anti-blocking layer. In that case, fine particles may be added to the back coat layer coating composition to provide an anti-blocking function. preferable.

  As fine particles added to the backcoat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxide. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low haze, and silicon dioxide is particularly preferable. These fine particles are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (manufactured by Nippon Aerosil Co., Ltd.). . Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used. Examples of the polymer fine particles include a silicone resin, a fluororesin, and an acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large anti-blocking effect while keeping haze low. The dynamic friction coefficient on the back side of the optical film used in this embodiment is preferably 0.9 or less, particularly preferably 0.1 to 0.9.

  The fine particles contained in the backcoat layer are preferably contained in an amount of 0.1 to 50% by mass, more preferably 0.1 to 10% by mass with respect to the binder. The increase in haze when the backcoat layer is provided is preferably 1% or less, more preferably 0.5% or less, and particularly preferably 0.0 to 0.1%.

  Specifically, the backcoat layer is preferably formed by applying a composition containing a solvent that dissolves or swells the transparent resin film (film substrate). The solvent to be used may include a solvent to be dissolved and / or a solvent to be swollen in addition to a solvent to be swelled, a composition in which these are mixed at an appropriate ratio depending on the degree of curl of the transparent resin film and the type of resin, and What is necessary is just to form by the application quantity.

  In order to enhance the curl prevention function, it is effective to increase the mixing ratio of the solvent for dissolving the solvent composition to be used and / or the solvent for swelling, and to decrease the ratio of the solvent not to be dissolved. This mixing ratio is preferably (solvent to be dissolved and / or solvent to be swollen) :( solvent not to be dissolved) = 10: 0 to 0.3: 9.7. Examples of the solvent for dissolving or swelling the transparent resin film contained in such a mixed composition include dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, cyclohexane, diacetone alcohol, 1 , 3-dioxolane, N-methylpyrrolidone, propylene glycol monomethyl ether acetate, propylene carbonate, cyclopentanone, 3-pentanone, 1,2-dimethoxyethane, tetrahydrofuran, ethyl lactate, bis (2-methoxyethyl) ether, acetic acid 2 -Methoxyethyl, propylene glycol dimethyl ether, trichloroethylene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, chloroform and the like. Examples of the solvent that does not dissolve include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, n-butanol, propylene glycol monomethyl ether, and hydrocarbons (toluene, xylene, cyclohexanol).

  These coating compositions are preferably applied to the surface of the transparent resin film with a gravure coater, dip coater, reverse coater, wire bar coater, die coater, etc., with a wet film thickness of 1 to 100 μm, particularly 5 to 30 μm. Preferably there is. The back coat layer may contain a resin as a binder. Examples of the resin used as the binder of the backcoat layer include vinyl chloride-vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, vinyl acetate-vinyl alcohol copolymer, partially hydrolyzed vinyl chloride-vinyl acetate copolymer. Polymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, ethylene-vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, etc. Vinyl polymer or copolymer, nitrocellulose, cellulose acetate propionate (preferably acetyl group substitution degree 1.8-2.3, propionyl group substitution degree 0.1-1.0), diacetyl cellulose, cellulose Cellulose derivatives such as acetate butyrate resin, maleic acid and / or Or acrylic acid copolymer, acrylic ester copolymer, acrylonitrile-styrene copolymer, chlorinated polyethylene, acrylonitrile-chlorinated polyethylene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, acrylic resin , Rubber resins such as polyvinyl acetal resin, polyvinyl butyral resin, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, styrene-butadiene resin, butadiene-acrylonitrile resin, Examples thereof include, but are not limited to, silicone resins and fluorine resins. For example, as an acrylic resin, Acrypet MD, VH, MF, V (manufactured by Mitsubishi Rayon Co., Ltd.), Hyperl M-4003, M-4005, M-4006, M-4202, M-5000, M-5001, M-4501 (manufactured by Negami Kogyo Co., Ltd.), Dialnal BR-50, BR-52, BR-53, BR-60, BR-64, BR-73, BR-75, BR-77, BR-79, BR -80, BR-82, BR-83, BR-85, BR-87, BR-88, BR-90, BR-93, BR-95, BR-100, BR-101, BR-102, BR-105 BR-106, BR-107, BR-108, BR-112, BR-113, BR-115, BR-116, BR-117, BR-118, etc. (Mitsubishi Rayon Co., Ltd.) acrylic and The methacrylic monomers such as various homopolymers and copolymers were prepared as raw materials are commercially available and can also be selected as appropriate preferred from among these. A cellulose resin layer such as diacetyl cellulose or cellulose acetate propionate is preferable.

  The order of coating the backcoat layer may be before or after coating the cured layer on the side opposite to the backcoat layer of the optical film, but if the backcoat layer also serves as an anti-blocking layer, coat it first. It is desirable to do. Alternatively, the back coat layer can be applied twice or more before and after the coating of the hardened layer.

<Optical film characteristics>
(Surface shape)
The arithmetic mean roughness Ra (JIS B0601: 2001) of the cured layer is preferably in the range of 2 to 100 nm, particularly preferably in the range of 2 to 20 nm. By setting the arithmetic average roughness Ra within the above range, the visibility and the clearness are excellent. The arithmetic average roughness Ra is a value measured with an optical interference surface roughness meter (manufactured by ZYGO, NewView) according to JIS B0601: 2001.

(Haze)
The haze of the optical film is preferably in the range of 0.05% to 10% in view of visibility when used in an image display device. Haze can be measured according to JIS K7105 and JIS K7136.

(hardness)
About the hardness of an optical film, it is preferable that the pencil hardness which is a parameter | index of hardness is HB or more. If the pencil hardness is equal to or higher than HB, it is difficult to be damaged in the polarizing plate forming step. The pencil hardness is specified by JIS K5400 using a test pencil specified by JIS S 6006 under the condition of a weight of 500 g after the prepared optical film is conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more. It is obtained by measuring according to the pencil hardness evaluation method.

<Film base>
The film base material of the optical film is mainly composed of a cellulose-based resin, particularly a cellulose ester. For example, examples of the film substrate include a cellulose diacetate film, a cellulose triacetate film, a cellulose acetate propionate film, and a cellulose acetate butyrate film.

  Examples of the commercially available cellulose ester film include Konica Minoltak KC8UX, KC4UX, KC8UY, KC4UY, KC6UA, KC4UA, KC2UA, KC4UE and KC4UZ (manufactured by Konica Minolta, Inc.). The refractive index of the cellulose ester film is preferably 1.45 to 1.55. The refractive index can be measured according to JIS K7142-2008.

(Cellulosic resin)
The cellulose resin (cellulose ester, cellulose ester resin) is preferably a lower fatty acid ester of cellulose. Lower fatty acid means a fatty acid having 6 or less carbon atoms. Examples of the lower fatty acid ester of cellulose include, for example, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate and the like, and mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate. it can. Particularly preferably used lower fatty acid esters of cellulose are cellulose diacetate, cellulose triacetate, and cellulose acetate propionate. These cellulose esters can be used alone or in combination.

  As the cellulose diacetate, those having an average degree of acetylation (bound acetic acid amount) of 51.0% to 56.0% are preferably used. Examples of commercially available products include L20, L30, L40, and L50 manufactured by Daicel Corporation, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical Japan Co., Ltd. .

  The cellulose triacetate preferably has an average degree of acetylation (bound acetic acid amount) of 54.0 to 62.5%, and more preferably cellulose triacetate having an average degree of acetylation of 58.0 to 62.5%. is there.

  The cellulose triacetate preferably contains cellulose triacetate A and cellulose triacetate B. Cellulose triacetate A is a cellulose triacetate having a number average molecular weight (Mn) of 125,000 or more and less than 155000, a weight average molecular weight (Mw) of 265,000 or more and less than 310,000, and Mw / Mn of 1.9 to 2.1. . Cellulose triacetate B has an acetyl group substitution degree of 2.75 to 2.90, Mn of 155,000 or more and less than 180,000, Mw of 290000 or more and less than 360,000, and Mw / Mn of 1.8 to 2.0. A cellulose triacetate.

Cellulose acetate propionate has an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, the following formula (I ) And (II) are preferably satisfied at the same time.
Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5

  Among them, it is preferable that 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9.

The method for measuring the substitution degree of the acyl group can be measured according to ASTM-D817-96. The number average molecular weight (Mn) and molecular weight distribution (Mw) of the cellulose ester can be measured using high performance liquid chromatography. The measurement conditions are as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G
(Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (Tosoh Corporation)
A calibration curve with 13 samples from Mw = 100000 to 500 was used. The 13 samples are preferably used at approximately equal intervals.

(Thermoplastic acrylic resin)
The film substrate may be configured by using a thermoplastic acrylic resin in combination with a cellulose ester resin. When using together, it is preferable that the containing mass ratio of a thermoplastic acrylic resin and a cellulose-ester resin is thermoplastic acrylic resin: cellulose-ester resin = 95: 5-50: 50.

Acrylic resin also includes methacrylic resin. Although it does not restrict | limit especially as an acrylic resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable. Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and the like. Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, Maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like may be mentioned, and these may be used alone or in combination of two or more.

  Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer, and methyl acrylate and n -Butyl acrylate is particularly preferably used. Moreover, it is preferable that a weight average molecular weight (Mw) is 80000-500000, More preferably, it exists in the range of 110000-500000.

  The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography. Commercially available acrylic resins include, for example, Delpet 60N, 80N (Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) )) And the like. Two or more acrylic resins can be used in combination.

(Λ / 4 film)
A λ / 4 film may be used as the film substrate. By using the λ / 4 film, when the optical film of the present embodiment is incorporated in an image display device, it is preferable from the viewpoint of excellent visibility and crosstalk.

  A λ / 4 film refers to a film having an in-plane retardation of the film of about ¼ for a predetermined wavelength of light (usually in the visible light region). The λ / 4 film is preferably a broadband λ / 4 film having a phase difference of approximately ¼ of the wavelength in the visible light wavelength range in order to obtain almost perfect circularly polarized light in the visible light wavelength range. .

The λ / 4 film has an in-plane retardation value Ro (550) measured at a wavelength of 550 nm, preferably in the range of 60 nm to 220 nm, more preferably in the range of 80 nm to 200 nm, and more preferably in the range of 90 nm to 190 nm. More preferably, it is the range. The in-plane retardation value Ro is represented by the following formula.
Ro = (nx−ny) × d
However, in the formula, nx and ny are the maximum refractive index in the plane of the film (also referred to as the refractive index in the slow axis direction) out of the refractive index at 23 ° C. and 55% RH and the wavelength of 550 nm, and in the plane of the film. It is the refractive index in the direction perpendicular to the slow axis, and d is the thickness (nm) of the film. Ro can be calculated by measuring the birefringence at each wavelength in an environment of 23 ° C. and 55% RH using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments).

  Further, in order to function effectively as a λ / 4 film, it is preferable to satisfy the relationship of Ro (590) −Ro (450) ≧ 2 nm at the same time, and Ro (590) −Ro (450) ≧ 5 nm. It is more preferable that Ro (590) -Ro (450) ≧ 10 nm. Note that Ro (A) indicates an in-plane retardation value measured at a wavelength of Anm.

  A circularly polarizing plate is obtained by laminating so that the angle between the slow axis of the λ / 4 film and the transmission axis of the polarizer described later is substantially 45 °. Substantially 45 ° means in the range of 30 ° to 60 °, more preferably in the range of 40 ° to 50 °. The angle between the slow axis in the plane of the λ / 4 film and the transmission axis of the polarizer is preferably 41 to 49 °, more preferably 42 to 48 °, and 43 to 47 °. Is still more preferable, and it is still more preferable that it is 44-46 degrees.

  The λ / 4 film is not particularly limited as long as it is an optically transparent resin. For example, an acrylic resin, a polycarbonate resin, a cycloolefin resin, a polyester resin, a polylactic acid resin, a polyvinyl alcohol resin, The cellulose-based resin described above can be used. Among these, from the viewpoint of chemical resistance, the λ / 4 film is preferably a cellulose resin or a polycarbonate resin. From the viewpoint of heat resistance, the λ / 4 film is preferably a cellulose resin.

(Retardation adjuster)
The retardation adjustment of λ / 4 can be performed by adding the following retardation adjusting agent to the above-described film base material. As the retardation adjusting agent, an aromatic compound having two or more aromatic rings as described in the specification of European Patent 911,656A2 can be used.

  Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocycle in addition to an aromatic hydrocarbon ring. Particularly preferred is an aromatic heterocycle, and the aromatic heterocycle is generally an unsaturated heterocycle. Of these, a 1,3,5-triazine ring is particularly preferred.

(Fine particles)
In order to improve the handling property, for example, acrylic particles, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate Further, it is preferable to contain inorganic fine particles such as magnesium silicate and calcium phosphate and a matting agent such as a crosslinked polymer. The acrylic particles are not particularly limited, but are preferably multi-layered acrylic granular composites. Among these, silicon dioxide is preferable in that the haze of the film substrate can be reduced. The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably in the range of 5 to 16 nm, and particularly preferably in the range of 5 to 12 nm.

(Ester compound)
It is preferable that a film base material contains the ester compound or sugar ester represented by the following general formula (X) from a viewpoint of the dimensional stability by environmental change. First, the ester compound represented by the general formula (X) will be described.

Formula (X) B- (GA) n-GB
(Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms) , A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)

  In the general formula (X), as the alkylene glycol component having 2 to 12 carbon atoms, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2 , 2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl- 1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl 1, -Hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, etc., and these glycols are one kind or two kinds or more Used as a mixture. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with cellulose acetate. Examples of the aryl glycol component having 6 to 12 carbon atoms include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol and the like, and these glycols can be used as one kind or a mixture of two or more kinds.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. These glycols are one kind or two or more kinds. Can be used as a mixture. Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. Used as a mixture of two or more. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid. Although the specific example (compound X-1-compound X-17) of a compound represented by general formula (X) below is shown, it is not limited to this.

(Sugar ester compound)
Next, the sugar ester compound will be described. The sugar ester compound is an ester other than cellulose ester, and is a compound obtained by esterifying all or part of the OH group of a sugar such as the following monosaccharide, disaccharide, trisaccharide or oligosaccharide. Examples of the sugar include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose And kestose. In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included. Among these compounds, compounds having a furanose structure and / or a pyranose structure are particularly preferable. Among these, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are preferable, and sucrose is more preferable. As oligosaccharides, maltooligosaccharides, isomaltooligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylo-oligosaccharides can also be preferably used.

  The monocarboxylic acid used for esterifying the sugar is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. The carboxylic acid to be used may be one kind or a mixture of two or more kinds. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid And unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include benzoic acid, aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralin An aromatic monocarboxylic acid having two or more benzene rings such as carboxylic acid, or a derivative thereof can be mentioned, and more specifically, xylic acid, hemelic acid, mesitylene acid, planicylic acid, γ-isojurylic acid, Julylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-, m, p-anisic acid, creosote acid, o- p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratrum acid o- veratric acid, gallic acid, asarone acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratric acid, o- homoveratric acid, Futaron acid, can be mentioned p- coumaric acid, especially benzoic acid. Among the ester compounds esterified, an acetyl compound into which an acetyl group has been introduced by esterification is preferable.

  The ester compound or sugar ester compound represented by the general formula (X) is preferably contained in the cellulose acetate film in an amount of 1 to 30% by mass, more preferably 5 to 25% by mass, and more preferably 5 to 20% by mass. It is particularly preferred that

(Plasticizer)
The film substrate may contain a plasticizer as necessary. The plasticizer is not particularly limited, but is a polycarboxylic acid ester plasticizer, glycolate plasticizer, phthalate ester plasticizer, phosphate ester plasticizer, polyhydric alcohol ester plasticizer, acrylic plasticizer. Agents and the like. In these, an acrylic plasticizer is preferable from the viewpoint of easily controlling the cellulose ester film to the retardation value described later.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  In addition, when making the film base material of this embodiment contain the plasticizer mentioned above, it is preferable to make it contain 1-50 mass% with respect to a cellulose acetate, It is more preferable to make 5-35 mass% contain, It is particularly preferable to contain 25% by mass.

(UV absorber)
The film base material of this embodiment may contain an ultraviolet absorber. Since the ultraviolet absorber absorbs ultraviolet rays of 400 nm or less, durability can be improved. In particular, the ultraviolet absorber preferably has a transmittance of 10% or less at a wavelength of 370 nm, more preferably 5% or less, and still more preferably 2% or less. Specific examples of the ultraviolet absorber are not particularly limited. For example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic powders. Examples include the body.

  More specifically, for example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6 -(Linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc. can be used. Commercially available products may be used. For example, TINUVIN such as TINUVIN 109, TINUVIN 171, TINUVIN 234, TINUVIN 326, TINUVIN 327, and TINUVIN 328 manufactured by BASF Japan Ltd. can be preferably used.

  Preferred ultraviolet absorbers are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferred are benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers. In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber. As the UV absorber, a polymer UV absorber can be preferably used, and a polymer type UV absorber is particularly preferably used.

  As a benzotriazole ultraviolet absorber, TINUVIN 109 (octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole-2-) manufactured by BASF Japan Ltd., which is a commercial product, is available. Yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate), TINUVIN 928 (2 -(2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol) and the like can be used. As the triazine-based ultraviolet absorber, TINUVIN 400 (2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -manufactured by BASF Japan Ltd., which is a commercial product, is available. Reaction product of 5-hydroxyphenyl and oxirane), TINUVIN 460 (2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3-5 Triazine), TINUVIN 405 (2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester Reaction products) and the like.

  The ultraviolet absorber is added by dissolving the ultraviolet absorber in an alcohol, such as methanol, ethanol, butanol or the like, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, and then becomes a film substrate. It may be added to the resin solution (dope) or directly during the dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose acetate to disperse and then added to the dope.

  0.5-10 mass% is preferable with respect to a cellulose acetate film, and, as for the usage-amount of a ultraviolet absorber, 0.6-4 mass% is still more preferable.

(Antioxidant)
The film substrate of the present embodiment may further contain an antioxidant (deterioration inhibitor). The antioxidant has a role of delaying or preventing the cellulose acetate film from being decomposed by a residual solvent amount of halogen in the cellulose acetate film, phosphoric acid of a phosphoric acid plasticizer, or the like. As the antioxidant, hindered phenol compounds are preferably used. For example, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl). -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate Etc. The addition amount of these compounds is preferably 1 ppm to 10000 ppm, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose acetate film.

(Disadvantage)
The film substrate preferably has a defect of 5 μm or more in diameter of 1 piece / 10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less. Here, the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape such as transfer of a roller scratch or an abrasion, the size can be confirmed by observing the defect with the reflected light of a differential interference microscope.

  When the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later process, the film may break with the defects as a starting point, and productivity may decrease. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Moreover, even when it cannot confirm visually, when a hardened layer is formed, a coating film cannot be formed uniformly and it may become a fault (coating omission). Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film. Further, the film substrate preferably has a breaking elongation of at least one direction of 10% or more, more preferably 20% or more, in the measurement based on JIS-K7127-1999. The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

(optical properties)
The film substrate preferably has a total light transmittance of 90% or more, more preferably 92% or more. Moreover, as a realistic upper limit, it is about 99%. The haze value is preferably 2% or less, more preferably 1.5% or less. The total light transmittance and haze value can be measured according to JIS K7361 and JIS K7136.

  The in-plane retardation value Ro of the film substrate is preferably in the range of 0 to 5 nm and the retardation value Rth in the thickness direction is in the range of −10 to 10 nm. Further, Rth is preferably in the range of -5 to 5 nm. Alternatively, the retardation Ro is preferably in the range of 30 to 200 nm, and more preferably in the range of 30 to 90 nm. The retardation Rth in the thickness direction is preferably in the range of 70 to 300 nm.

The in-plane retardation Ro value is defined by the following formula (I), and the retardation value Rth in the thickness direction is defined by the following formula (II).
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the plane of the film base, ny is the refractive index in the direction perpendicular to the slow axis in the plane of the film base, and nz is the thickness direction of the film base) (Refractive index, d represents the thickness (nm) of the film substrate, respectively.)

  The retardation can be obtained at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH (relative humidity) using, for example, KOBRA-21ADH (manufactured by Oji Scientific Instruments).

<Film formation of cellulose ester film>
Next, although the example of the film forming method of the cellulose-ester film which is an example of a film base material is demonstrated, the film forming method is not limited to this. As a method for producing a cellulose ester film, production methods such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, a hot press method and the like can be used.

(Organic solvent)
An organic solvent useful for forming a resin solution (dope composition) in the case of producing a cellulose ester film by a solution casting film forming method described later is one that can simultaneously dissolve a cellulose ester resin and other additives. Can be used without limitation. For example, as the chlorinated organic solvent, methylene chloride, as the 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, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, etc. Can, methylene chloride, methyl acetate, ethyl acetate, may be used preferably acetone. The solvent is preferably a dope composition in which a total of 15 to 45 mass% of a cellulose ester resin and other additives are dissolved.

(Solution casting film forming method)
In the solution casting film forming method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-shaped or drum-shaped metal support, and drying the cast dope as a web It is carried out by a step of peeling off from the metal support, a step of stretching or maintaining the width, a step of further drying, and a step of winding up the finished cellulose ester film.

  As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.

  The width of the cast (casting) can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

  The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.

  When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. .

  In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

In order for the cellulose ester film to obtain good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 60%. It is 130 mass%, Most preferably, it is 20-30 mass% or 70-120 mass%. The amount of residual solvent is defined by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
In addition, M is the mass of the sample collected at any time during or after the production of the web or film, and N is the mass after heating at 115 ° C. for 1 hour.

  In the drying step of the cellulose ester film, the web is peeled off from the metal support and dried to make the residual solvent amount 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0. It is -0.01 mass% or less.

  In the film drying step, generally, a roller drying method (a method in which webs are alternately passed through a plurality of upper and lower rollers) and a method of drying while conveying the web by a tenter method are employed.

  In the stretching step, the film can be sequentially or simultaneously stretched in the longitudinal direction (MD direction) and the width direction (TD direction) of the film. The draw ratios in the biaxial directions perpendicular to each other are preferably 1.0 to 2.0 times in the MD direction and 1.05 to 2.0 times in the TD direction, respectively. More preferably, it is carried out in the range of 1.0 to 1.5 times and 1.05 to 2.0 times in the TD direction. For example, a method of making a difference in peripheral speed between a plurality of rollers and stretching in the MD direction using the difference in peripheral speed of the roller between them, fixing both ends of the web with clips and pins, and widening the interval between the clips and pins in the traveling direction And a method of stretching in the MD direction, a method of stretching in the lateral direction and stretching in the TD direction, a method of stretching the MD direction and the TD direction simultaneously, and stretching in both directions.

  These width maintenance or width direction stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  The film transport tension in the film forming process such as a tenter depends on the temperature, but is preferably 120 to 200 N / m, more preferably 140 to 200 N / m, and most preferably 140 to 160 N / m.

  The temperature during stretching is (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C., more preferably (Tg-5), where Tg is the glass transition temperature of the cellulose ester film. ~ (Tg + 20) ° C.

  The Tg of the cellulose ester film can be controlled by the material type constituting the film and the ratio of the constituting materials. The Tg when the cellulose ester film is dried is preferably 110 ° C. or higher, more preferably 120 ° C. or higher. Especially preferably, it is 150 degreeC or more. The glass transition temperature is preferably 190 ° C. or lower, more preferably 170 ° C. or lower. The Tg of the cellulose ester film can be determined by the method described in JIS K7121. The stretching temperature is preferably 150 ° C. or more and the stretching ratio is 1.15 times or more because the surface is appropriately roughened. Roughening the surface of the cellulose ester film is preferable because it improves slipperiness and improves surface processability.

(Melt casting method)
The cellulose ester film may be formed by a melt casting film forming method. In the melt casting film forming method, a composition containing other additives such as a cellulose ester resin and a plasticizer is heated and melted to a temperature showing fluidity, and then a melt containing the fluid cellulose ester is cast. To do.

  In the melt casting film forming method, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded in advance and pelletized.

  Pelletization may be performed by a known method, for example, dry cellulose ester, plasticizer, and other additives are fed to an extruder with a feeder, kneaded using a single or twin screw extruder, and formed into a strand from a die. Can be extruded, water-cooled or air-cooled, and then cut.

  The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  The extruder is preferably processed at a temperature as low as possible so that it can be pelletized so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

  Using a single or twin screw extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matter, and then formed into a film from a T die. The cellulose ester film is formed by niping the film with a cooling roller and an elastic touch roller and solidifying the film on the cooling roller.

  When introducing from the supply hopper to the extruder, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  The extrusion flow rate is preferably adjusted stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

  Additives such as plasticizers and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

  The temperature of the cellulose ester film on the touch roller side when the cellulose ester film is nipped by the cooling roller and the elastic touch roller is preferably not less than Tg (Tg + 110 ° C.) of the film. A known roller can be used as the roller having an elastic surface used for such a purpose.

  The elastic touch roller is also called a pinching rotary member. A commercially available elastic touch roller can also be used.

  When peeling the cellulose ester film from the cooling roller, it is preferable to control the tension to prevent deformation of the film.

  Moreover, it is preferable that the cellulose ester film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roller.

  As a stretching method, a known roller stretching machine, a tenter or the like can be preferably used. The stretching temperature is preferably carried out in the temperature range of Tg to (Tg + 60) ° C. of the resin that usually constitutes the film.

  Prior to winding, the ends may be slit and trimmed to the product width, and knurled (embossing) may be applied to both ends to prevent sticking during winding and scratching. The knurling method can be performed by heating or pressurizing using a metal ring having an uneven pattern on the side surface. The grip portion of the clip at both ends of the film is usually cut out and reused because the cellulose ester film is deformed and cannot be used as a product.

(Manufacturing method of obliquely stretched film)
The λ / 4 film can be produced by a method for producing an obliquely stretched film. The method for producing an obliquely stretched film is a method for producing a stretched film having a slow axis at an angle of more than 0 ° and less than 90 ° with respect to the extending direction of the film. As the unstretched film before oblique stretching, the cellulose ester film described above can be used.

  Here, the angle with respect to the extending direction of the film is an angle in the film plane. Since the slow axis is usually expressed in the stretching direction or a direction perpendicular to the stretching direction, stretching having such a slow axis is performed by stretching at an angle of more than 0 ° and less than 90 ° with respect to the extending direction of the film. A film can be manufactured.

  The angle (orientation angle θ) formed by the extension direction of the film and the slow axis can be arbitrarily set to a desired angle in the range of more than 0 ° and less than 90 °, more preferably 10 ° to 80 °. °, more preferably 40 ° to 50 °.

(Diagonal stretching)
The obliquely stretched film can be produced using an obliquely stretching apparatus (obliquely stretched tenter). As an obliquely stretched tenter, the orientation angle of the film can be set freely by changing the rail pattern in various ways, and furthermore, the orientation axis of the film can be oriented with high precision evenly on the left and right across the width direction of the film. An apparatus capable of controlling the film thickness and retardation with high accuracy can be preferably used.

(Physical properties of film substrate)
As for the film thickness of a cellulose-ester film base material, 5-200 micrometers is preferable, More preferably, it is 5-80 micrometers, Most preferably, it is 5-34 micrometers. By forming the cured layer of this embodiment on a thin cellulose ester film substrate, the effect of this embodiment is more easily exhibited. Moreover, 500-10000m is preferable and, as for the length of a film base material, More preferably, it is 1000-8000m. By setting it as the range of the said length, it is excellent in the processability in application | coating, such as a hardened layer, and the handleability of film base itself.

  Moreover, arithmetic mean roughness Ra of a film base material becomes like this. Preferably it is 2-10 nm, More preferably, it is 2-5 nm. The arithmetic average roughness Ra can be measured according to JIS B0601: 1994.

<Other layers>
The optical film of this embodiment can be provided with other layers such as an antireflection layer and a conductive layer.

(Antireflection layer)
The optical film of this embodiment can be used as an antireflection film having an external light antireflection function by coating an antireflection layer on a cured layer.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is composed of a low refractive index layer having a lower refractive index than the protective film as the support, or a combination of a high refractive index layer and a low refractive index layer having a higher refractive index than the protective film as the support. Preferably it is.

<Low refractive index layer>
The low refractive index layer preferably contains silica-based fine particles, and the refractive index is preferably in the range of 1.30 to 1.45 when measured at 23 ° C. and a wavelength of 550 nm.

  The film thickness of the low refractive index layer is preferably in the range of 5 nm to 0.5 μm, more preferably in the range of 10 nm to 0.3 μm, and in the range of 30 nm to 0.2 μm. Most preferred.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and porous or hollow inside are preferably hollow silica-based fine particles.

The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.
General formula (OSi-1): Si (OR) ₄
In the formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used as the organosilicon compound represented by the general formula.

  Further, a compound having a thermosetting property and / or a photocurable property, which mainly contains a fluorine-containing compound containing a fluorine atom in a range of 35 to 80% by mass and containing a crosslinkable or polymerizable functional group, has a low refractive index. You may make it contain in the composition for layer formation. Specifically, a fluorine-containing polymer or a fluorine-containing sol-gel compound is used. As the fluorine-containing polymer, for example, a hydrofluorinated monomer in addition to a hydrolyzate or dehydration condensate of a perfluoroalkyl group-containing silane compound [for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane] Examples thereof include fluorine-containing copolymers having units and cross-linking reactive units as constituent units. In addition, you may add a solvent, a silane coupling agent, a hardening | curing agent, surfactant, etc. to the composition for low refractive index layer formation as needed.

<High refractive index layer>
In the high refractive index layer, it is preferable to adjust the refractive index to a range of 1.4 to 2.2 by measuring at 23 ° C. and a wavelength of 550 nm. The thickness of the high refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm. Adjustment of the refractive index can be achieved by adding metal oxide fine particles and the like. The metal oxide fine particles used preferably have a refractive index of 1.80 to 2.60, more preferably 1.85 to 2.50.

  The kind of metal oxide fine particles is not particularly limited, and Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S A metal oxide having at least one element selected from can be used.

<Conductive layer>
In the optical film, a conductive layer may be formed on the cured layer. As the conductive layer provided, a generally well-known conductive material can be used. For example, metal oxides such as indium oxide, tin oxide, indium tin oxide, gold, silver, and palladium can be used. These can be formed as a thin film on an optical film by a vacuum deposition method, a sputtering method, an ion plating method, a solution coating method, or the like. Moreover, it is also possible to form a conductive layer using the organic conductive material which is the above-described π-conjugated conductive polymer.

  In particular, a conductive material that is excellent in transparency and conductivity, and that has a main component of any of indium oxide, tin oxide, and indium tin oxide, which can be obtained at a relatively low cost, can be suitably used. Although the thickness of the conductive layer varies depending on the material to be applied, it cannot be said unconditionally. However, the surface resistivity is 1000Ω or less, preferably 500Ω or less, and considering the economy, A range of 10 nm or more, preferably 20 nm or more and 80 nm or less, preferably 70 nm or less is suitable. In such a thin film, visible light interference fringes due to uneven thickness of the conductive layer are unlikely to occur.

<Polarizing plate>
Next, a polarizing plate using the optical film of this embodiment will be described. The polarizing plate can be produced by a general method. For example, although it can be bonded using an active energy ray-curable adhesive or the like, a polarizing film (polarizer) produced by subjecting the optical film to alkali saponification treatment and immersing and stretching the treated optical film in an iodine solution It is preferable to attach to one side of this using a completely saponified polyvinyl alcohol aqueous solution (water glue, water-based adhesive).

  The optical film may be bonded to the other surface of the polarizer, or the above-described film substrate may be bonded. The thickness of the film substrate to be bonded to the other surface is preferably in the range of 5 to 100 μm, more preferably in the range of 5 to 34 μm, from the viewpoints of adjusting smoothness and curl balance and further enhancing the effect of preventing winding deviation.

  A polarizing film, which is a main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction, and a typical polarizing film that is currently known is a polyvinyl alcohol polarizing film. The polarizing film includes a polyvinyl alcohol film dyed with iodine and a dichroic dye dyed, but is not limited thereto.

  As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxial stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. The thickness of the polarizing film is 5 to 30 μm, preferably 8 to 15 μm.

<Circularly polarizing plate>
A circularly polarizing plate can also be constituted using an optical film. That is, a circularly polarizing plate can be formed by laminating a polarizing plate protective film, a polarizer, and a λ / 4 film in this order. In this case, the angle formed between the slow axis of the λ / 4 film and the absorption axis (or transmission axis) of the polarizing film is 45 °. A long polarizing plate protective film, a long polarizer, and a long λ / 4 film (long diagonally stretched film) are preferably laminated in this order.

  The circularly polarizing plate can be produced by using a stretched polyvinyl alcohol doped with iodine or a dichroic dye as a polarizer, and laminating with a configuration of λ / 4 film / polarizer. The film thickness of the polarizer is 5 to 40 μm, preferably 5 to 30 μm, and particularly preferably 5 to 20 μm.

  The circularly polarizing plate can be produced by a general method. In other words, it is preferable to attach an alkali saponified λ / 4 film to one surface of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution, using a completely saponified polyvinyl alcohol aqueous solution.

<Adhesive layer>
In order to bond the substrate of the liquid crystal cell and the polarizing plate, the pressure-sensitive adhesive layer used on one side of the film of the polarizing plate is preferably optically transparent and exhibits moderate viscoelasticity and pressure-sensitive adhesive properties.

  Specific examples of the adhesive layer include adhesives or adhesives such as acrylic copolymers, epoxy resins, polyurethane, silicone polymers, polyethers, butyral resins, polyamide resins, polyvinyl alcohol resins, and synthetic rubbers. A film such as a drying method, a chemical curing method, a thermal curing method, a thermal melting method, a photocuring method, or the like can be formed and cured using a polymer such as the above. Among them, the acrylic copolymer can be preferably used because it is most easy to control the physical properties of the adhesive and is excellent in transparency, weather resistance, durability and the like.

<Image display device>
The optical film of this embodiment is preferable in that the performance excellent in visibility is exhibited by using it for an image display apparatus. As an image display device, a reflection type, a transmission type, a transflective type liquid crystal display device, a liquid crystal display device of various driving methods such as a TN type, an STN type, an OCB type, a VA type, an IPS type, and an ECB type, an organic EL display Examples thereof include a device and a plasma display. Among these image display devices, a liquid crystal display device is preferable because of its high visibility.

  The protection part may be arrange | positioned in the further visual recognition side of the cured layer of the optical film of a visual recognition side polarizing plate. This protection part can be constituted by a front plate or a touch panel. The said protection part is bonded together by the said hardened layer via the filler (photocurable resin) for filling the space | gap between hardened layers. The front plate in particular of a protection part is not restrict | limited, A conventionally well-known thing, such as an acrylic board and a glass plate, can be used. Further, the material, thickness, and the like of the front plate can be appropriately selected according to the use of the image display device.

  As the filler, a solvent-free filler is preferable, and as commercially available products, for example, SVR1120, SVR1150, SVR1320 (above, manufactured by Dexerials Corporation), or HRJ-60, HRJ-302, HRJ-53 (above, Kyoritsu Chemical Industry) And the like). When using a filler, one type may be used independently and multiple types may be used together.

  Bonding of the optical film and the front plate can be performed, for example, as follows. First, a filler is prepared. Then, a filler is applied to the surface of the cured layer of the optical film, and the front plate is overlaid on the coating film of the filler. In this state, the filler is cured by light irradiation or the like, and the optical film and the front plate are bonded together. When the filler is applied to the surface of the cured layer, the surface free energy of the cured layer is set to 30 mN / m or more so that the filler is uniformly spread without being repelled at the end of the cured layer. An image display device that is maintained and has excellent visibility can be obtained.

〔Example〕
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<Preparation of optical film 1>
[Production of Cellulose Ester Film 1]
<Preparation of silicon dioxide dispersion>
Aerosil R812 (Nippon Aerosil Co., Ltd., average primary particle diameter of 7 nm)
10 parts by mass Ethanol 90 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed for 30 minutes with a dissolver to prepare a silicon dioxide dispersion dilution. It filtered with the fine particle dispersion | distribution dilution liquid filter (Advantech Toyo Co., Ltd .: Polypropylene wind cartridge filter TCW-PPS-1N).

<Preparation of Dope Composition 1>
(Cellulose ester resin)
Cellulose triacetate A (cellulose triacetate synthesized from linter cotton, acetyl group substitution degree 2.88, Mn = 14000) 90 parts by mass (additive)
Ester Represented by General Formula (X) (Exemplary Compound X-1) 5 parts by mass Ester Represented by General Formula (X) (Exemplary Compound X-12) 4 parts by mass (UV absorber)
TINUVIN 928 (manufactured by BASF Japan Ltd.) 3 parts by mass (fine particles)
Silicon dioxide dispersion dilution 4 parts by mass (solvent)
Methylene chloride 432 parts by mass Ethanol 38 parts by mass The above was put into a sealed container, heated and stirred, and dissolved completely. Azumi filter paper No. Azumi filter paper No. 24 was used to prepare a dope (dope composition 1).

  Next, the belt casting apparatus was used to uniformly cast on a stainless steel band support. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100% by mass, and the stainless steel band support was peeled off. The cellulose ester film web was evaporated at 35 ° C., slit to 1.15 m width, obliquely stretched with an oblique stretching tenter at a stretching temperature of 175 ° C. and a stretching ratio of 1.5 times, and a take-up tension at the tenter outlet of 200 N / m, the film was stretched in an oblique direction so that the orientation angle θ (an angle formed by the film width direction and the slow axis) was 45 °. Then, it was dried for 15 minutes while being transported in a drying device at 120 ° C. with a number of rollers, slitted to a width of 1.3 m, knurled with a width of 10 mm and a height of 5 μm at both ends of the film, and wound around a core. The cellulose ester film 1 as a λ / 4 film was obtained. The film thickness of the cellulose ester film 1 was 15 μm, the winding length was 3900 m, the in-plane retardation Ro was 135 nm, the thickness direction retardation Rt was 140 nm, and the orientation angle θ was 45 °.

[Preparation of polymer silane coupling agent coated fine particles]
In a container, 30 ml of methyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd .: Light Ester M), 1 ml of 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-803), 100 ml of tetrahydrofuran as a solvent, polymerization initiator Was added 50 mg of azoisobutyronitrile (manufactured by Kanto Chemical Co., Inc .: AIBN) and substituted with N ₂ gas, and then heated at 80 ° C. for 3 hours to prepare a polymer silane coupling agent. The obtained polymer silane coupling agent had a molecular weight of 16,000. The molecular weight was measured with a gel permeation chromatography apparatus.

Next, silica sol (manufactured by JGC Catalysts & Chemicals Co., Ltd .: Si-45P, SiO ₂ concentration 30% by weight, average particle diameter 45 nm, dispersion medium: water) is ion-exchanged with an ion exchange resin, and an ultrafiltration membrane method is used. The solvent of water was replaced with ethanol to prepare 100 g of an ethanol dispersion of silica fine particles (SiO ₂ concentration of 30% by weight).

  100 g of the silica fine particle ethanol dispersion and 1.5 g of the polymer silane coupling agent are dispersed in 20 g (25 ml) of acetone, and 20 mg of aqueous ammonia having a concentration of 29.8% by weight is added thereto, followed by stirring at room temperature for 30 hours. The polymer silane coupling agent was adsorbed on the silica fine particles.

  Thereafter, silica particles having an average particle diameter of 5 μm are added and stirred for 2 hours to adsorb the unadsorbed polymer silane coupling agent in the solution to the silica particles, and then the polymer silane coupling that has not been adsorbed by centrifugation. Silica particles having an average particle diameter of 5 μm adsorbing the agent were removed. 1000 g of ethanol is added to the silica fine particle dispersion adsorbing the polymer silane coupling agent, and the silica fine particles are precipitated, separated, dried under reduced pressure, and then dried at 25 ° C. for 8 hours to obtain a polymer silane coupling agent-coated silica (1 ) The obtained polymer silane coupling agent-coated silica (1) had an average particle size of 57 nm. The average particle size was measured with a laser particle size measuring device.

[Preparation of buffer layer composition]
The buffer layer composition was prepared by stirring and mixing the polymer silane coupling agent-coated silica (1) prepared above and the following compound.
(Fine particles)
Polymer silane coupling agent-coated silica (1) 60 parts by mass (active ray curable resin)
Urethane acrylate (U-4H, Shin-Nakamura Chemical Co., Ltd.) 35 parts by mass (photopolymerization initiator)
Irgacure 184 (manufactured by BASF Japan) 5 parts by mass (additive)
KF-642 (polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.)
2 parts by mass (solvent)
Propylene glycol monomethyl ether 80 parts by weight Methyl acetate 20 parts by weight

[Preparation of cured layer composition]
The polymer silane coupling agent-coated silica (1) prepared above was stirred and mixed with the following compound to prepare a cured layer composition.
(Fine particles)
Polymer silane coupling agent-coated silica (1) 60 parts by mass (active ray curable resin)
NK ester A-DCP (tricyclodecane dimethanol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) 35 parts by mass (photopolymerization initiator)
Irgacure 184 (manufactured by BASF Japan) 5 parts by mass (additive)
KF-642 (polyether-modified silicone oil, manufactured by Shin-Etsu Chemical Co., Ltd.)
2 parts by mass (solvent)
Propylene glycol monomethyl ether 80 parts by weight Methyl acetate 20 parts by weight

[Preparation of optical film 1]
The buffer layer composition is applied on the side A of the produced cellulose ester film 1 (the surface not in contact with the casting belt) using an extrusion coater, and the constant rate drying section temperature is 50 ° C., the decreasing rate drying section. After drying at a temperature of 50 ° C., while purging with nitrogen so that the oxygen concentration becomes 1.0 vol% or less, the illuminance of the irradiated part is 100 mW / cm ² using an ultraviolet lamp, and the irradiation amount is 0.25 J / The coating layer was cured as cm ² to form a buffer layer (lower layer) having a dry film thickness of 4 μm.

Subsequently, the cured layer composition prepared above was applied onto the buffer layer using a micro gravure coater, and after drying at a constant rate drying zone temperature of 50 ° C. and a reduced rate drying zone temperature of 50 ° C., the oxygen concentration was While purging with nitrogen to an atmosphere of 1.0% by volume or less, using an ultraviolet lamp, the illuminance of the irradiated part is 100 mW / cm ² , the irradiation amount is 0.3 J / cm ² , the coating layer is cured, and a dry film A cured layer (upper layer) having a thickness of 2 μm was formed, wound up in a roll shape, and the optical film 1 was produced.

[Measurement of reaction rate]
The resin reaction rate in the buffer layer was measured by the ATR method (Attenuated Total Reflection) as follows. That is, using a Fourier transform infrared spectrophotometer (FT-IR Magna 860-NIC plan IR-Microscope manufactured by Nicorey), carbon- before curing of the resin of the buffer layer (resin in which the solvent was volatilized from the coating solution) and infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, a carbon - equivalent to oxygen double bond was measured with infrared absorption intensity of 1725 cm ^-1, determined their ratio a, the buffer layer resin after curing, the carbon - infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, carbon - determine the ratio B between the infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond, the following From the equation, the reaction rate T (%) was determined.
T (%) = {(A−B) / A} × 100

  Moreover, the resin reaction rate in the cured layer was also measured by the same method as described above.

<Preparation of optical films 2-4>
The optical film 1 except that the buffer layer was formed by changing the conditions (drying temperature, UV irradiation amount, etc.) for curing the resin of the buffer layer so that the resin reaction rate in the buffer layer would be the value shown in Table 1. Optical films 2 to 4 were produced in the same manner as in the above.

<Preparation of optical films 5-7>
The content of fine particles (polymer silane coupling agent-coated silica (1)) contained in the buffer layer is changed to the value shown in Table 1, and the curing conditions are set so that the resin reaction rate of the buffer layer becomes the value shown in Table 1. Optical films 5 to 7 were prepared in the same manner as the optical film 1 except that the buffer layer was formed by changing.

<Preparation of optical film 8>
The optical film 8 is produced in the same manner as the optical film 7 except that the resin contained in the buffer layer and the content thereof are changed from urethane acrylate (35 parts by mass) to non-urethane acrylate resin (100 parts by mass). did. The non-urethane acrylate resin is pentaerythritol tri / tetraacrylate (NK ester A-TMM-3L, manufactured by Shin-Nakamura Chemical Co., Ltd.).

<Preparation of optical film 9>
An optical film 9 was produced in the same manner as in the production of the optical film 1 except that the buffer layer was formed without including fine particles (polymer silane coupling agent-coated silica (1)).

<Preparation of optical film 10>
An optical film 10 was prepared in the same manner as the optical film 1 except that both the buffer layer and the cured layer were formed without including fine particles (polymer silane coupling agent-coated silica (1)).

<Preparation of optical film 11>
An optical film 11 was prepared in the same manner as the optical film 1 except that the cured layer was formed without including fine particles (polymer silane coupling agent-coated silica (1)).

<Preparation of optical film 12>
An optical film 12 was prepared in the same manner as the optical film 1 except that a cured layer was directly formed on the cellulose ester film 1 without forming a buffer layer.

<Preparation of Polarizing Plate 101>
The optical film 1 was attached to one surface of the polarizing film, and a commercially available optical film KC4UZ (manufactured by Konica Minolta) was attached to the other surface of the polarizing film to produce a polarizing plate 101. More details are as follows.

(A) Production of Polarizing Film What was impregnated with 10 parts by mass of glycerin and 170 parts by mass of water in 100 parts by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) having a saponification degree of 99.95 mol% and a polymerization degree of 2400. After melt-kneading and defoaming, it was melt extruded from a T die onto a metal roll to form a film. Then, it dried and heat-processed and obtained the PVA film. The obtained PVA film had an average thickness of 15 μm, a moisture content of 2.4%, and a film width of 3 m.

  Next, the obtained PVA film was continuously processed in the order of preliminary swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to prepare a polarizing film. That is, the PVA film was preliminarily swollen in water at a temperature of 30 ° C. for 30 seconds, and immersed in an aqueous solution having an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 40 g / liter at a temperature of 35 ° C. for 3 minutes. Subsequently, the film was uniaxially stretched 6 times in a 50% aqueous solution with a boric acid concentration of 4% under the condition that the tension applied to the film was 700 N / m, and the potassium iodide concentration was 40 g / liter and the boric acid concentration was 40 g / liter. Then, it was immersed in an aqueous solution having a zinc chloride concentration of 10 g / liter and a temperature of 30 ° C. for 5 minutes for fixing. Thereafter, the PVA film was taken out, dried with hot air at a temperature of 40 ° C., and further heat-treated at a temperature of 100 ° C. for 5 minutes. The obtained polarizing film had an average thickness of 5 μm, polarization performance of transmittance of 43.0%, polarization degree of 99.5%, and dichroic ratio of 40.1.

(B) Production of Polarizing Plate A polarizing plate was produced according to the following steps 1 to 5.

  Process 1: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the storage tank of the polyvinyl alcohol adhesive agent solution of 2 mass% of solid content.

Process 2: The alkali saponification process was implemented on the following conditions with respect to the optical film 1 and KC4UZ. Next, excess adhesive adhered to the polarizing film immersed in the polyvinyl alcohol adhesive solution in Step 1 was lightly removed, and this polarizing film was sandwiched between the opposite surface of the optical film 1 from the cured layer and KC4UZ, and laminated.
(Alkaline saponification treatment)
Saponification step 4M-KOH 50 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds Neutralization step 10 parts HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds After saponification treatment, water washing, neutralization, water washing are performed in this order. It is then dried at 100 ° C.

Step 3: The laminate was sandwiched between two rotating rollers and bonded at a pressure of ^{20 to} 30 N / cm ² at a speed of about 2 m / min. At this time, it was carried out with care to prevent bubbles from entering.

  Step 4: The sample prepared in Step 3 was dried in a dryer at a temperature of 100 ° C. for 5 minutes to prepare a polarizing plate.

  Step 5: Apply a commercially available acrylic adhesive to the protective film (KC4UZ) side of the polarizing plate prepared in Step 4 so that the thickness after drying is 5 μm, and dry in an oven at 110 ° C. for 5 minutes to form an adhesive layer And a peelable protective film was attached to the adhesive layer. This polarizing plate was cut (punched) to produce a polarizing plate 101.

<Production of Liquid Crystal Display Device 201>
The upper polarizing plate of a commercially available liquid crystal display device (60 type display BRAVIA LX900 manufactured by SONY) was peeled off, and the polarizing plate 101 was attached to the liquid crystal cell as the upper polarizing plate. That is, the adhesive layer of the polarizing plate 101 and the glass of the liquid crystal cell were bonded so that KC4UZ of the polarizing plate 101 was on the liquid crystal cell side. At this time, the crossed Nicols were arranged so that the transmission axis of the upper polarizing plate (polarizing plate 101) was in the vertical direction and the transmission axis of the lower polarizing plate was in the horizontal direction.

<Preparation of polarizing plates 102-112>
Polarizing plates 102 to 112 were prepared in the same manner as the polarizing plate 101 except that the optical film 1 of the polarizing plate 101 was changed to the optical films 2 to 12, respectively.

<Production of liquid crystal display devices 202 to 212>
Liquid crystal display devices 202 to 212 were manufactured in the same manner as the liquid crystal display device 101 except that the polarizing plate 101 was changed to the polarizing plates 102 to 112.

<Evaluation>
(Crosstalk evaluation)
Immediately after turning on the backlight of each liquid crystal display device in an environment of 23 ° C. and 55% RH, 3D glasses (SONY TDG-BR100) are attached, and the 3D glasses are inclined 85 ° from the vertical direction while lying down. In such a state, the 3D video was viewed and the crosstalk (decrease in luminance) was evaluated based on the following criteria.
"Evaluation criteria"
○: No crosstalk.
Δ: Crosstalk is slightly visible, but there is no problem.
X: Crosstalk is clearly seen and is a problem level.

(Evaluation of cracking by keystroke test)
In a variable air-conditioning room (AES-200 manufactured by Asahi Kagaku Co., Ltd.) controlled at 35 ° C. and 90% RH, a polarizing plate 101- The input pen was pressed 15,000 times against 112 (optical films 1 to 12) under the conditions of a keystroke speed of 2 Hz and a load of 150 g. The pen tip material of the input pen is polyacetal, and the radius of curvature R of the pen tip is 0.8 mm. And the film state after pressing an input pen was observed, and it evaluated about the crack of the hardened layer based on the following references | standards.
"Evaluation criteria"
(Double-circle): There is no deformation | transformation of an optical film and there is no crack of a hardened layer.
○: Slight dent marks are visible on the optical film, but there is no crack in the cured layer.
Δ: Although cracks occur in the hardened layer, there is no problem in practical use because the cracks are not so great that glare can be seen during display.
X: A crack occurs in the hardened layer, and glare is visible even when the display is displayed.

(hardness)
The prepared optical films 1 to 12 are conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more, and then specified by JIS K5400 using a test pencil specified by JIS S 6006 under a weighted 500 g condition. According to the pencil hardness evaluation method, the pencil hardness of the optical film (cured layer) was measured and evaluated based on the following criteria.
"Evaluation criteria"
○: Pencil hardness is H or more.
(Triangle | delta): Pencil hardness is F or more and less than H.
X: Pencil hardness is less than F.

  Table 1 shows main compositions, parameters, and evaluation results of each of the optical films 1 to 12. In Table 1, UA indicates urethane acrylate, and PETA indicates pentaerythritol tri / tetraacrylate.

  From Table 1, in the optical films 9, 10, and 12, the evaluation of crosstalk and cracks is poor (x). This is because the optical films 9, 10 and 12 do not contain fine particles (polymer silane coupling agent-coated silica (1)) in the buffer layer, and the buffer layer does not have hygroscopicity. The water content of the water paste stays on the cellulose ester film (water does not escape from the cellulose ester film to the buffer layer), and it is considered that crosstalk occurs due to the phase difference fluctuation caused by the water content. In addition, it is considered that the cellulose ester film is deformed by moisture, and this causes a load such as tensile stress on the cured layer, so that the cured layer is easily broken.

  Moreover, in the optical films 10 and 11, evaluation of hardness is inferior (x). This is considered to be because the optical films 10 and 11 do not have high hardness because the hardened layer does not contain the fine particles.

  On the other hand, in the optical films 1-8, evaluation is favorable (any of (triangle | delta), (circle), (double-circle)) about all of crosstalk, a crack, and hardness. This is because a buffer layer is provided between the film substrate (cellulose ester film) and the cured layer, and the buffer layer contains the fine particles, so that the moisture content of the film substrate is reduced and the moisture content is reduced. This is considered to be due to the fact that a certain degree of hardness is ensured in the hardened layer because the phase difference fluctuation and deformation are reduced, and the hardened layer contains the fine particles.

  In particular, from the evaluation of the optical films 7 and 8, it can be said that it is preferable to use a relatively hard urethane acrylate as the resin used for the buffer layer located in the lower layer of the cured layer from the viewpoint of further improving the hardness.

  Furthermore, from the evaluation of the optical films 1 to 4, the resin reaction rate of the buffer layer is 20% or more and 40% in order to obtain better evaluation results for all of crosstalk, cracks, and hardness (◯ for all). It can be said that the following is desirable. If the resin reaction rate is less than 20%, it is considered that it is difficult to impart an appropriate hardness to the buffer layer and to impart an appropriate hardness to the cured layer thereon (optical film 4). See Hardness Evaluation). Further, if the resin reaction rate exceeds 40%, the buffer layer becomes too hard and the buffer property is lowered, so that it is considered difficult to reduce the crack of the cured layer on the buffer layer (optical). Refer to evaluation of cracks in film 1). In addition, if the buffer layer becomes too hard, the hygroscopicity of the buffer layer decreases, and moisture entering the film substrate cannot be efficiently released to the buffer layer, so the water content of the film substrate (λ / 4 film) It is considered that crosstalk caused by the phenomenon tends to occur (see evaluation of crosstalk of the optical film 1).

  Moreover, from the viewpoint of reliably reducing cracks in the cured layer from the evaluation of the optical films 1 to 4 and the optical films 5 to 8, the content a (part by mass) of the fine particles contained in the cured layer and the buffer layer are included. It can be said that the ratio a / b to the content b (parts by mass) of the fine particles is preferably 2 or more and 10 or less. When the ratio a / b is less than 2, the content b of the fine particles in the buffer layer is excessively increased, the buffer layer becomes hard, and the buffering property of the buffer layer is lowered, and the ratio a / b is 10 If the amount exceeds 1, the content a of the fine particles in the cured layer becomes too large and the cured layer itself becomes brittle. In any case, the cured layer is considered to be easily broken when an external force is applied.

  In addition, in the optical films 1 to 8 in which a buffer layer is provided between the film substrate and the cured layer, any interference unevenness due to the refractive index difference between the cured layer and the buffer layer is not observed, and black display The visibility was all good.

  The optical film of the present invention can be used for image display devices such as polarizing plates and liquid crystal display devices.

1 Image display device 4 Liquid crystal cell (display cell)
DESCRIPTION OF SYMBOLS 5 Polarizing plate 11 Polarizer 12 Film base material 13 Buffer layer 14 Hardened layer 16 Optical film

Claims (6)

A film substrate as a λ / 4 film made of a cellulose-based resin;
A cured layer containing a resin having an alicyclic structure and fine particles coated with a polymer silane coupling agent;
Having a buffer layer formed between the film substrate and the cured layer;
The said buffer layer contains resin different from the said resin of the said hardening layer, and the microparticles | fine-particles coat | covered with the polymer silane coupling agent, The optical film characterized by the above-mentioned.   The optical film according to claim 1, wherein the resin of the buffer layer is a urethane acrylate resin. 3. The optical film according to claim 1, wherein the following reaction rate T of the resin obtained based on IR spectrum measurement in the buffer layer is 20% or more and 40% or less.
T (%) = {(A−B) / A} × 100
However,
A is before curing of the resin of the buffer layer, a carbon - infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, a carbon - infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond The ratio of
B is after curing of the resin of the buffer layer, a carbon - infrared absorption intensity of 810 cm ^-1 corresponding to carbon double bond, a carbon - infrared absorption intensity of 1725 cm ^-1 corresponding to oxygen double bond The ratio of   The ratio a / b between the content a (parts by mass) of the fine particles contained in the cured layer and the content b (parts by mass) of the fine particles contained in the buffer layer is 2 or more and 10 or less. The optical film according to claim 1, wherein the optical film is a film. The optical film according to claim 1, and a polarizer.
The polarizing plate, wherein the film base of the optical film is bonded to one surface of the polarizer with water glue.   An image display device, wherein the polarizing plate according to claim 5 is provided on at least one surface side of the display cell.

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