JP6470585B2 - POLYMER FILM, LAMINATED FILM, PROCESS FOR PRODUCING THE SAME, POLARIZING PLATE, AND IMAGE DISPLAY DEVICE - Google Patents

Description

  The present invention relates to a polymer film, a laminated film and a method for producing the same, a polarizing plate, and an image display device.

  A flat panel display such as a liquid crystal display device (hereinafter also referred to as LCD (Liquid Crystal Display)) usually contains one or more films (polymer film) containing a polymer as a constituent component.

  The polymer film is incorporated into a flat panel display as a protective film in an LCD, for example (see, for example, Patent Document 1). In addition to flat panel displays, polymer films are widely used in various fields as protective films for protecting the surface and improving durability.

  On the other hand, regarding a polymer film, forming a cured layer obtained by curing a polymerizable composition on a polymer film and using it as a laminated film has also been proposed (see, for example, Patent Document 2).

JP 2002-20410 A JP2013-132785A

  In the laminated film in which the cured layer is formed on the polymer film as described above, the cured layer can contribute to increasing the scratch resistance of the film surface and increasing the film strength. However, if a cured layer is provided only on one side of the polymer film, curling occurs in the laminated film due to warping of the polymer film to the cured layer side (single side) due to curing shrinkage during the formation of the cured layer. Workability at the time of pasting to other members will fall.

With respect to the above points, Patent Document 2 discloses that a cured layer (described as a hard coat layer in Patent Document 2) is formed on both sides of a polymer film in order to suppress curling.
On the other hand, for example, Patent Document 1 describes that a polymer film (described as a cellulose ester film in Patent Document 1) is bonded to a polarizer and used as a polarizing plate protective film. Usually, it is used by being bonded to a member to be protected. Therefore, it is calculated | required that a protective film is excellent in the adhesiveness at the time of bonding with another member.
In addition, the property desired for the protective film includes high visible light transmittance. This is because a protective film having a low visible light transmittance causes a decrease in transparency of a member or apparatus incorporating the film.

Among the various polymers that can constitute the polymer film, cellulose acylate is said to be a preferred polymer from the viewpoint of the transparency of the polymer film containing the polymer film and the adhesion to other members. Therefore, a polymer film containing cellulose acylate is widely used as a protective film such as a polarizing plate protective film.
However, according to the study by the present inventors, the laminated film having a cured layer on each side of the polymer film containing cellulose acylate does not have sufficient adhesion when bonded to other members, and peeling occurs. It became clear that. The present inventors consider that this is a factor that the surface of the cured layer rather than the surface of the polymer film containing cellulose acylate becomes a bonding surface with another member. However, in a laminated film having a cured layer on both sides for curling suppression, one of the cured layer surfaces must be a bonding surface. In addition, when a hardened layer is provided on both sides, the interface between the polymer film and the hardened layer is increased by one as compared with a case where a hardened layer is provided only on one side, and therefore light scattering and refraction at the interface are likely to occur. As a result, the visible light transmittance is reduced as compared with a laminated film having a cured layer only on one side.
Thus, for a laminated film in which a cured layer is laminated on a polymer film containing cellulose acylate, both curl suppression and suitability as a protective film (adhesion with other members and visible light transmittance) are achieved. This has been difficult with the prior art.

  Accordingly, an object of the present invention is a polymer film containing cellulose acylate, which can suppress curling when a cured layer is laminated, and a laminated film obtained by laminating a cured layer is suitable as a protective film. It is providing the polymer film which is excellent in.

As a result of intensive studies to achieve the above object, the present inventors have found that the following polymer films:
A polymer film comprising at least component A and component B,
Component A is cellulose acylate,
Component B is one or more components selected from the group consisting of a polymerizable compound and a polymer of a polymerizable compound,
The surface layer part on the first surface side and the surface layer part on the second surface side, which is the surface opposite to the first surface, each contain component A and component B,
The content of component A in the surface portion on the first surface side is 10% by mass or more and the content of component B is 30% by mass or more,
Component A and component B are also present in the region between the surface layer portion on the first surface side and the surface layer portion on the second surface side, and the surface layer on the second surface side from the surface layer portion on the first surface side A polymer film in which the content of component B decreases toward the part,
Newly found. The polymer film can provide a laminated film in which curling is suppressed by providing a cured layer on the second surface side. Furthermore, by adhering the first surface to another member, good adhesion to this member can be shown. In addition, the laminated film thus obtained can exhibit a higher visible light transmittance than a laminated film having a cured layer on both sides.
The inference by the present inventors regarding the above points will be described later.

  The “surface layer portion” of the polymer film refers to a region from the surface to 0.50 μm in the film thickness direction. In the present invention, the composition (content ratio of component A, component B, etc.) of the region (surface layer portion) and the region located inside the film from the surface layer portion is determined by composition analysis by Raman spectroscopy. The reason for defining the surface layer portion as described above is that the spatial resolution of measurement by Raman spectroscopy is taken into consideration. Note that Raman spectroscopy is one of analytical methods that can accurately analyze the composition of a film sample.

Specifically, the composition of each region of the polymer film is determined by Raman spectroscopy as follows.
Cut the polymer film in the thickness direction, and in the cut surface, the region from the surface of the polymer film to the thickness direction of 0.50 μm (surface layer part on one surface side. Specifically, the distance from the surface is 0.25 μm Where the peak of the light intensity profile of the excitation light for Raman spectroscopy is applied (the beam diameter is 0.50 μmφ)), the measurement is started at every 0.50 μm interval. The composition is analyzed by Raman spectroscopy. Similar to the measurement at the surface layer portion, at each measurement point (each having a thickness of 0.50 μm), the peak of the light intensity profile of the excitation light for Raman spectroscopy is applied to the center of the measurement point (the beam diameter is 0.50 μmφ). ). Note that if measurement is performed at 0.50 μm intervals from the surface layer on the one surface side to the other surface, which is the starting point for composition analysis, the second measurement point from the end and the measurement point that is the end point of measurement (the other surface) In some cases, the distance between the upper part and the upper part is less than 0.50 μm. In this case, composition analysis by Raman spectroscopy is performed on a region (surface layer portion on the other surface) from the surface opposite to the surface of the polymer film to the thickness direction of 0.50 μm. In this way, composition analysis of the surface layer portion on one surface side of the polymer film, the surface layer portion on the other surface side, and the region located between these surface layer portions can be performed. For example, at a plurality of measurement positions separated by a constant interval of about 1 to 10 cm in the in-plane direction, measurement points may be taken at intervals of 0.50 μm in the thickness direction as described above.
Details of the composition analysis by Raman spectroscopy will be described in detail in the examples described later. In addition, for a polymer film whose component is unknown, the component can be separated from the polymer film by a known separation method such as solvent extraction, and the separated component can be identified by a known identification method. The composition of each layer can be determined by performing composition analysis by Raman spectroscopy for the component thus identified. Examples of the identification method include an NMR method (nuclear magnetic resonance spectroscopy), an IR method (infrared spectroscopy), and an MS method (mass spectrometry).
In the composition analysis, “not detected” includes a case where it is not included at all and a case where a trace amount is included in an amount below the detection limit by Raman spectroscopy. The detection limit by Raman spectroscopy is, for example, 1% by mass or less. When not detected in this way, the content rate is expressed as 0%.
Moreover, the cut surface which performs a composition analysis is at least 1 surface, and may be two or more cut surfaces cut | disconnected in arbitrary positions. As an example, a cut surface can be obtained at a position spaced apart by a fixed interval of about 1 to 10 cm. The number of the plurality of cut surfaces is, for example, about 2 to 20. In addition, when composition analysis is performed on a plurality of cut surfaces, each layer is defined by an arithmetic average value of analysis results on the plurality of cut surfaces.

In the polymer film, of the one surface and the other surface, the surface on the surface layer portion side having a high component B content is defined as the first surface, and the surface on the surface layer portion side having a low content of component B is defined as the second surface. The surface.
Further, “the component A and the component B are also present in the region between the surface portion on the first surface side and the surface layer portion on the second surface side” means that in the composition analysis by the Raman spectroscopy described above, It means that component A and component B are each detected at a content of more than 1% by mass in all measurement locations other than the surface layer portion on one surface side and the surface layer portion on the second surface side. Moreover, "the content rate of the component B falls from the surface layer part of the 1st surface side toward the surface layer part of the 2nd surface side" means that the content rate of the component B in the center part of a polymer film is 1st. It means that it is lower than the content rate of component B in the surface layer portion on the surface side and higher than the content rate of component B in the surface layer portion on the second surface side. That is, the content of component B in the surface layer portion on the first surface side is “α _B ” mass%, the content of component B in the center portion is “β _B ” mass%, and the component in the surface layer portion on the second surface side When the content rate of _B is “γ _B ” mass%, it means that the relationship “α _B > β _B > γ _B ” is satisfied. Here, the content rate of the component B in the center part of a polymer film is a value calculated | required as follows. Taking the surface of any one of the polymer films as the starting point (depth 0 μm), the horizontal position represents the depth position in the film thickness direction of each measurement location, and the vertical axis represents the content of component B determined by Raman spectroscopy. The content rate of component B at the measurement position is plotted. In the curve obtained by approximating the graph obtained in this way to a quadratic function using the method of least squares, if the center of the thickness of the polymer film, that is, the thickness of the polymer film is “X” μm, Let the content rate of the component B in the position of an axis | shaft "X / 2" micrometer be the content rate of the component B in the center part of a polymer film.
In addition, the thickness of the polymer film in this invention and this specification shall be a value measured with a stylus-type film thickness meter.

  In one aspect | mode, the content rate of the component B in the surface layer part of the 1st surface side is the range of 40-80 mass% in the said polymer film.

  In one aspect | mode, the content rate of the component B in the surface layer part of the 2nd surface side is the range of 5-20 mass% in the said polymer film.

  In one aspect | mode, the content rate of the component A in the surface layer part of the 1st surface side is the range of 20-60 mass% in the said polymer film.

In one mode, in the above-mentioned polymer film, the content rate of ingredient A falls from the surface part of the 2nd surface side toward the surface layer part of the 1st surface side. Here, “the content rate of component A decreases from the surface layer portion on the second surface side toward the surface layer portion on the first surface side” means that the content rate of component A in the central portion of the polymer film is It means that it is lower than the content of component A in the surface layer portion on the surface side and higher than the content of component A in the surface layer portion on the first surface side. That is, the content of the component A in the surface layer portion on the first surface side is “α _A ” mass%, the content of the component A in the center portion is “β _A ” mass%, and the component in the surface layer portion on the second surface side When the content of A is “γ _A ” mass%, this means that the relationship “α _A <β _A <γ _A ” is satisfied. The method for obtaining the content of component A in the central part of the polymer film is as described above for the content of component B.

  In one aspect | mode, the said cellulose acylate contains a cellulose acetate.

  In one aspect | mode, the molecular weight of the said polymeric compound is the range of 250-3000.

  In one aspect, the value obtained by dividing the molecular weight of the polymerizable compound by the number of polymerizable groups contained in one molecule is in the range of 30 to 500.

  In one aspect | mode, the said polymeric compound has a polymeric group containing an ethylenically unsaturated bond.

  In one aspect, the polymerizable group containing an ethylenically unsaturated bond is a polymerizable group selected from the group consisting of a (meth) acryloyl group and a (meth) acryloyloxy group. In the present invention and the present specification, the description of “(meth) acryloyl group” is used in the meaning of at least one of an acryloyl group and a methacryloyl group. The same applies to “(meth) acryloyloxy group”, “(meth) acrylate”, “(meth) acryl” and the like to be described later.

A further aspect of the invention provides:
A laminated film having the polymer film and an adjacent layer adjacent to the second surface of the polymer film, and the adjacent layer is a cured layer obtained by curing the polymerizable composition;
About.

  In the present invention and the present specification, the “polymerizable composition” is a composition containing at least one polymerizable compound and has a property of being cured by being subjected to a polymerization treatment such as light irradiation and heating. The “polymerizable compound” is a compound containing one or more polymerizable groups in one molecule. The polymerizable group is a group that can participate in the polymerization reaction, and will be described in detail later.

A further aspect of the invention provides:
A method for producing the laminated film,
A first composition comprising cellulose acylate, a polymerizable compound and an organic solvent; and a cellulose acylate and an organic solvent comprising a polymerizable compound at a concentration lower than the polymerizable compound concentration of the first composition. Forming a cast film by co-casting with a second composition containing a polymerizable compound;
Subjecting the cast film formed to a polymerization treatment;
Before or after applying the polymerization treatment to the cast film, applying a polymerizable composition for forming an adjacent layer to the second composition side surface; and
Subjecting the polymerization composition for forming the adjacent layer to a polymerization treatment;
A method for producing the laminated film,
About.

  In one aspect, the casting film is also polymerized by the polymerization process performed on the polymerizable composition for forming an adjacent layer. In one embodiment, such a polymerization process is performed by light irradiation.

A further aspect of the invention provides:
A polarizing plate comprising at least the laminated film and a polarizer adjacent to the first surface of the polymer film contained in the laminated film;
About.

A further aspect of the invention provides:
An image display device comprising at least one selected from the group consisting of the laminated film and the polarizing plate,
About.

According to the present invention, there is provided a polymer film containing cellulose acylate, which can suppress curling when a cured layer is laminated, and the laminated film thus obtained is excellent in suitability as a protective film. can do. Furthermore, according to this invention, the above-mentioned laminated film containing the said polymer film and its manufacturing method can also be provided.
Furthermore, according to this invention, the polarizing plate and image display apparatus containing the said laminated | multilayer film can also be provided.

It is a partially enlarged view of a solution casting film forming apparatus including a casting die capable of co-casting. It is a graph which shows the content rate change of the component A in the thickness direction of the polymer film obtained in Example 1, and the component B. FIG. It is explanatory drawing of the curl evaluation in an Example.

  The following description may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In the present invention and this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present invention and the present specification, unless otherwise specified, a certain component (for example, component A, component B, solvent, etc.) may be included in a film or a composition, and two or more of them may be combined in any combination. It may be included in any proportion. In addition, the proportion of a certain component in a film, a composition, or the like refers to the total of two or more types unless the component includes two or more types.

[Polymer film]
The polymer film according to one embodiment of the present invention is a polymer film containing at least component A and component B, wherein component A is cellulose acylate, and component B is a group consisting of a polymerizable compound and a polymer of the polymerizable compound. One or more components selected from the group consisting of component A and component B in the surface layer portion on the first surface side and the surface layer portion on the second surface side which is the surface opposite to the first surface, The content of component A in the surface layer portion on one surface side is 10% by mass or more and the content rate of component B is 30% by mass or more, and the surface layer portion on the first surface side and the surface layer portion on the second surface side The component A and the component B exist also in the area | region between these, and the content rate of the component B falls from the surface layer part of the 1st surface side toward the surface layer part of the 2nd surface side.

  The present inventors consider the reason why the above-described object can be achieved by the polymer film as follows (1) to (3). However, the following description is a guess by the present inventors and does not limit the present invention.

(1) The curl described above is due to the fact that the cured film shrinks only on one side of the polymer film, thereby applying a force to the polymer film to deform the film only on one side (cured layer side). It is thought that it occurs. Therefore, it is considered that curling can be suppressed by providing a cured layer on each side of the polymer film to prevent the polymer film from being deformed only on one side. However, providing a cured layer on each side of the polymer film decreases suitability as a protective film (adhesion with other members and visible light transmittance).
On the other hand, in the polymer film according to one embodiment of the present invention, the surface layer portion on the first surface side, the surface layer portion on the second surface side that is the surface opposite to the first surface, and both surface layer portions described above Component B exists in the area between. Here, Component B is one or more components selected from the group consisting of “polymerizable compound” and “polymer of polymerizable compound”. In such a polymer film, the content rate of component B in the surface layer portion on the first surface side is 30% by mass or more, and the content rate of component B decreases toward the surface layer portion on the second surface side, It means that there is a concentration gradient in which the first surface side is a high concentration region of component B and the second surface side is a low concentration region of component B in the film thickness direction. When an adjacent layer (cured layer) obtained by curing the polymerizable composition by polymerization treatment is laminated on the surface (second surface) on the low concentration region side of component B of this polymer film, a cured layer is formed only on one side. A laminated film is obtained. In the laminated film thus obtained, it is considered that the high-concentration region of component B in the polymer film can be in a state similar to a state in which a hardened layer is formed on both sides by acting as a hardened layer. The present inventors consider that this is the reason why the polymer film according to one embodiment of the present invention makes it possible to obtain a laminated film in which curling is suppressed. Furthermore, curling can be suppressed without forming a cured layer on both sides. Therefore, according to the polymer film, a laminated film having a higher visible light transmittance than a laminated film having a cured layer formed on each side is provided. Can be provided.
The polymer film includes a polymer film containing a polymerizable compound before the polymerization treatment. Such a polymer film is obtained by, for example, performing a polymerization treatment before lamination of the adjacent layer (cured layer) or a polymerization compound contained in the film by a polymerization process for forming the adjacent layer (cured layer). Is polymerized to form a polymer film containing a polymer of a polymerizable compound.

(2) In the above polymer film, the surface layer portion on the first surface side, the surface layer portion on the second surface side which is the surface opposite to the first surface, and the region between both surface layer portions described above, A (cellulose acylate) is present. Further, as described above, the surface layer portion on the first surface side and the surface layer portion on the second surface side which is the surface opposite to the first surface, and the region between the two surface layer portions described above, B is also present. The presence of component A and component B over the entire polymer film as described above is also the reason why a laminated film having a high visible light transmittance can be provided by laminating an adjacent layer (cured layer) on this polymer film. The present inventors infer that.

(3) Furthermore, in the polymer film, the content of component A (cellulose acylate) in the surface layer portion on the first surface side is 10% by mass or more. Cellulose acylate is a component that can contribute to improving the adhesion between the polymer film containing the cellulose acylate and other members. When such a component is present in the surface layer portion on one surface side (first surface side) of 10% by mass or more, the laminated film containing this polymer film was bonded to another member (for example, a polarizer). The present inventors speculate that this contributes to suppressing the occurrence of peeling. On the other hand, in the laminated film in which the cured layers are formed on both sides in order to suppress curling, the bonding surface with the other member is either one of the cured layer surfaces. This is considered to be the reason why the laminated film in which the cured layers are formed on both sides of the polymer film does not have sufficient adhesion with other members.

  As described above, in the polymer film, component A is present at 10% by mass or more and component B is present at 30% by mass or more in the surface layer portion on the first surface side. The present inventors presume that this is the reason why it is possible to provide a laminated film in which curling suppression and adhesion improvement with other members are compatible by forming a cured layer on the second surface side). .

  However, the above is an inference by the present inventors and does not limit the present invention as described above.

<Composition distribution in polymer film>
(Distribution of component A)
In the polymer film, the content of component A (cellulose acylate) in the surface layer portion on the first surface side is 10% by mass or more. As described above, this is from the viewpoint of improving the adhesion when another member is bonded to the first surface side. That is, when the content of component A in the surface layer portion on the first surface side is 10% by mass or more, occurrence of peeling when another member is bonded to the first surface side can be suppressed. . From the viewpoint of realizing better adhesion, the content of component A in the surface layer portion on the first surface side is preferably 20% by mass or more, more preferably 25% by mass or more, and 30 The content is more preferably at least mass%, more preferably at least 35 mass%, even more preferably at least 40 mass%, and the higher the content, the more preferable.
Moreover, since the content rate of the component B in the surface layer part of the 1st surface side is 30 mass% or more, the content rate of the component A in the surface layer part of the 1st surface side is 70 mass% or less. is there. The content of component A in the surface layer portion on the first surface side is preferably 60% by mass or less, and preferably 50% by mass or less from the viewpoint of further curling of the laminated film provided with the cured layer. It is more preferable.

  On the other hand, the content rate of the component A in the surface layer part of the 2nd surface side may be 10 mass% or more, and may be less than 10 mass%. As described above, in the polymer film, the component A is present in the surface layer portion on the first surface side, the surface layer portion on the second surface side, and the region between the both surface layer portions. In the polymer film, since the content of component B decreases from the surface layer portion on the first surface side toward the surface layer portion on the second surface side, the content rate of component A is relatively low on the first surface side. There is a tendency to increase from the surface layer portion toward the surface layer portion on the second surface side (that is, decrease from the surface layer portion on the second surface side toward the surface layer portion on the first surface side). From the viewpoint of adhesion between the adjacent layer and the second surface in the laminated film obtained by forming the adjacent layer (cured layer) on the second surface side of the polymer film, the surface layer portion on the second surface side The content of component A is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. The present inventors speculate that this is because component A (cellulose acylate) contributes to the improvement of brittleness on the side of the bonding surface (second surface) with the adjacent layer (cured layer) of the polymer film. However, this is only an estimation and does not limit the present invention.

(Distribution of component B)
In the polymer film, the content of component B in the surface layer portion on the first surface side is 30% by mass or more. Thereby, as described above, by providing a cured layer on one side, it is possible to provide a laminated film in which curling is suppressed without providing a cured layer on both sides. From the viewpoint of further curling, the content of component B in the surface layer portion on the first surface side is preferably 40% by mass or more, more preferably 50% by mass or more, and 60% by mass. More preferably, the higher the content, the more preferable. Moreover, since the content rate of the component A in the surface layer part of the 1st surface side is 10 mass% or more, the content rate of the component B in the surface layer part of the 1st surface side is 90 mass% or less. is there. The content of component A in the surface portion on the first surface side is 80% by mass or less from the viewpoint of further improving the adhesion when another member is bonded to the first surface side. Preferably, it is 70 mass% or less.

  In the polymer film, the component B is present in a surface layer portion on the first surface side, a surface layer portion on the second surface side, and a region between the both surface layer portions. And the content rate of the component B falls toward the surface layer part of the 2nd surface side from the surface layer part of the 1st surface side. Therefore, the content rate of component B in the surface layer portion on the second surface side is lower than the content rate of component B in the surface layer portion on the first surface side. The content rate of the component B in the surface layer part on the second surface side can be, for example, about 3 to 50% by mass, but if it is lower than the content rate of the component B in the surface layer part on the first surface side, 3% by mass. % Or more than 50% by mass. In one aspect, from the viewpoint of improving the adhesion with the adjacent layer (cured layer) of the polymer film, the content of component B in the surface layer portion on the second surface side is in the range of 5 to 20% by mass. preferable. In this regard, the inventors have improved the brittleness on the bonding surface (second surface) side when the content of component B in the surface layer portion on the second surface side is in the range of 5 to 20% by mass. A cross-linked structure that is considered to be formed near the interface between the adjacent layer and the polymer film in a mode in which the polymer film is also polymerized by the polymerization process for forming the adjacent layer as will be described in detail later. Although it is guessed that the adhesion improvement by can be achieved, it is only a guess and does not limit the present invention at all.

The content of component B in the surface layer portion on the first surface side is α _B , the content rate of component B in the central portion is β _B , and the content rate of component B in the surface layer portion on the second surface side is γ _B. As described above, the polymer film satisfies the relationship of α _B > β _B > γ _B. Further, from the viewpoint of further curling suppression, the difference “α _B −γ _B ” between the component B contents in both surface layers is preferably 5% by mass or more, and more preferably 10% by mass or more. It is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and further preferably 50% by mass or more.

  Next, the detail of each component which comprises a polymer film is demonstrated sequentially.

<Component A>
Component A is cellulose acylate. There is no restriction | limiting in particular as a cellulose acylate. JP, 2012-215812, A paragraph 0017 can be referred to for the details of the acyl group which substitutes the hydroxyl group of cellulose in cellulose acylate. Preferably, the acyl group is an acetyl group, a propionyl group, or a butanoyl group, more preferably an acetyl group or a propionyl group, and still more preferably an acetyl group. That is, the polymer film preferably contains cellulose acetate as cellulose acylate (component A). From the viewpoint of optical performance (film transparency, etc.), cellulose acylate having an acetyl substitution degree of 2.95 or less is preferable, more preferably 2.90 or less, and still more preferably 2.89 or less. On the other hand, from the viewpoint of solvent solubility and the like, cellulose acylate having an acetyl substitution degree of 2.00 or more is preferable, more preferably 2.50 or more, and still more preferably 2.80 or more. From the same viewpoint, the total acyl substitution degree of the cellulose acylate is also preferably in the above-described range for the acetyl substitution degree. The total acyl substitution degree and acetyl substitution degree can be measured according to the method prescribed in ASTM-D817-96. The portion not substituted with an acyl group usually exists as a hydroxyl group. In addition, for details of cellulose acylate, paragraphs 0017 to 0020 of JP2012-215812A can also be referred to.

<Component B>
Component B is one or more components selected from the group consisting of a polymerizable compound and a polymer of a polymerizable compound. As described above, the polymer film includes a polymer film containing a polymerizable compound before the polymerization treatment. That is, a polymer film that becomes a polymer film containing a polymer of a polymerizable compound by being subjected to a polymerization treatment such as light irradiation or heating is also an embodiment of the polymer film. In addition, the polymer film is a polymer film that is divided into a plurality of processes that are performed twice or more, and is a polymer film in which a part of the plurality of processes is performed, and then the remainder of the plurality of processes The polymer film in which the step is performed is also an embodiment of the polymer film.

  The polymerizable compound may be a monofunctional polymerizable compound containing one polymerizable group in one molecule or a polyfunctional polymerizable compound containing two or more identical or different polymerizable groups in one molecule. Good. The polymerizable compound may be a monomer or a multimer such as an oligomer or a prepolymer. The polymerizable compound contained in the polymer film and the polymerizable compound constituting the polymer contained in the polymer film may be one kind alone, or a combination of two or more kinds in any ratio. When two or more kinds of polymerizable compounds are used, the combination of two or more kinds of polymerizable compounds is a combination of two or more kinds of monofunctional polymerizable compounds, a combination of two or more kinds of polyfunctional polymerizable compounds, and one or more kinds. Any combination of the monofunctional polymerizable compound and one or more polyfunctional polymerizable compounds may be used.

The molecular weight of the polymerizable compound is, for example, 80 or more and 30,000 or less, but may be lower or higher than this range. The means for providing the polymer film with the distribution of component B described in detail above is not particularly limited as long as it is a means capable of giving such distribution. As an example of the above means, there can be mentioned a method of using compositions having different concentrations of the polymerizable compound as a composition for performing co-casting as described later. For example, when the first composition containing the polymerizable compound and the second composition not containing the polymerizable compound are co-cast, the polymerizable compound contained in the first composition is changed to the second composition. The component B is contained in the region between the surface layer portion on the first surface side, the surface layer portion on the second surface side and the surface layer portion on both sides and the both surface layer portions, and the component B described above in the film thickness direction. A polymer film having a distribution can be obtained. The diffusion of the polymerizable compound can be controlled by the molecular weight of the polymerizable compound, co-casting conditions, and the like. From the viewpoint of ease of production of the polymer film having the distribution of component B described above, the molecular weight of the polymerizable compound is preferably 250 or more, more preferably 500 or more, and 1000 or more. Is more preferable. Further, from the same viewpoint, the molecular weight of the polymerizable compound is preferably 3000 or less.
In addition, in this invention and this specification, molecular weight shall mean the weight average molecular weight measured in polystyrene conversion by gel permeation chromatography (GPC) about a multimer. Examples of specific measurement conditions include the following measurement conditions. The weight average molecular weight described later is a value measured under the following measurement conditions.
GPC device: HLC-8120 (manufactured by Tosoh Corporation):
Column: TSK gel Multipore HXL-M (Tosoh Corporation, 7.8 mm ID (inner diameter) × 30.0 cm)
Eluent: Tetrahydrofuran (THF)

  The polymerizable group may be a radical polymerizable group or a cationic polymerizable group, and is preferably a radical polymerizable group. From the viewpoint of the reactivity of the polymerization reaction, polymerizable groups such as an ethylenically unsaturated bond-containing group, an epoxy group, an oxetane group, and a methylol group can be exemplified, and an ethylenically unsaturated bond-containing group is more preferable. Examples of the ethylenically unsaturated bond-containing group include (meth) acryloyloxy group, (meth) acryloyl group, vinyl group, styryl group, and allyl group, and (meth) acryloyloxy group and (meth) acryloyl group include More preferred is a (meth) acryloyloxy group. About a polyfunctional polymerizable compound, the number of the polymeric groups contained in a compound is 2 or more in 1 molecule, Preferably it is the range of 2-20, More preferably, it is the range of 3-12. The value obtained by dividing the molecular weight of the polymerizable compound by the number of polymerizable groups contained in one molecule (hereinafter also referred to as “polymerizable group equivalent”) has the distribution of component B described above. From the viewpoint of ease of production of the polymer film, it is preferably 30 or more, and more preferably 50 or more. Also, the smaller the polymerizable group equivalent, the greater the amount of cure shrinkage when polymerized, so from the viewpoint of curl suppression, the polymerizable group equivalent is preferably 500 or less, preferably 300 or less. Is more preferable, and it is still more preferable that it is 200 or less.

As one aspect | mode of a preferable polymeric compound, the polyfunctional (meth) acrylate compound which has 2 or more of ethylenically unsaturated bond containing groups in 1 molecule can be mentioned.
Specific examples of the bifunctional (meth) acrylate include ethylene glycol di (meth) acrylate, bisphenol A tetraethoxydi (meth) acrylate, bisphenol A tetrapropoxydi (meth) acrylate, 1,6-hexanediol di (meth) ) Acrylate, neopentyl glycol di (meth) acrylate, and the like. As an example of a commercial item, Kyoeisha Chemical Co., Ltd. make: Light acrylate NP-A (neopentyl glycol diacrylate, molecular weight 212) etc. can also be mentioned.
Examples of the tri- or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and dipenta Examples include erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and isocyanuric acid-modified tri (meth) acrylate. Examples of commercially available products include Nippon Kayaku Co., Ltd .: KAYARAD DPHA (dipentaerythritol hexaacrylate, molecular weight 579), Toagosei Co., Ltd .: Aronix M-309 (trimethylolpropane triacrylate, molecular weight 296) and the like. it can.
The (meth) acrylate compound may be one in which a part of the molecular skeleton is modified. For example, those modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol or the like can be used.

  In addition, examples of the polymerizable compound include urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, (meth) acrylate polymer, and the like. ) Acrylate is preferred. Urethane (meth) acrylate can be obtained by reaction of polyhydric alcohol and organic diisocyanate with hydroxy (meth) acrylate.

  Examples of the polyhydric alcohol include neopentyl glycol, 3-methyl-1,5-pentanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, and pentaerythritol. , Tricyclodecane dimethylol, bis- [hydroxymethyl] -cyclohexane, etc .; the above polyhydric alcohols and polybasic acids (for example, succinic acid, phthalic acid, hexahydrophthalic anhydride, terephthalic acid, adipic acid, azelaic acid, tetrahydroanhydride) Polyester polyol obtained by reaction with phthalic acid, etc .; polycaprolactone polyol obtained by reaction of the polyhydric alcohol and ε-caprolactone; polycarbonate polyol (for example, 1,6-hexanediol and the like) Polycarbonate diols obtained by the reaction of phenyl carbonate); and can include polyether polyols. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and ethylene oxide-modified bisphenol A.

  Examples of the organic polyisocyanate include isophorone diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, diphenylmethane-4,4′-diisocyanate, dicyclopentanyl isocyanate and the like, adducts of these isocyanate compounds, or these Examples include isocyanate multimers.

  Examples of the hydroxy (meth) acrylate compound include pentaerythritol tri (meth) acrylate, pentaerythritol di (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, hydroxyethyl (meth) ) Acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, dimethylol cyclohexyl mono (meth) acrylate, hydroxycaprolactone (meth) acrylate, and the like. Among these, pentaerythritol tri (meth) acrylate and dipentaerythritol penta (meth) acrylate are preferable.

  The urethane (meth) acrylate is preferably 6 or more functional and more preferably 6 to 15 functional.

  A commercially available product may be used as the urethane (meth) acrylate. Examples of commercially available products include: Nippon Synthetic Chemical Industry: UV1700B (weight average molecular weight 2000, 10 functional), UV7600B (weight average molecular weight 1500, 6 functional), Nippon Kayaku Co., Ltd .: DPHA40H (weight average molecular weight 7000, 10 Functionality), UX5003 (weight average molecular weight 700, 6 functionalities), Negami Kogyo Co., Ltd .: UN3320HS (weight average molecular weight 5000, 15 functionalities), UN904 (weight average molecular weight 4900, 15 functionalities), UN3320HC (weight average molecular weight 1500, 10 functionalities) ), UN3320HA (weight average molecular weight 1500, 6 functional), manufactured by Arakawa Chemical Industries, Ltd .: BS577 (weight average molecular weight 1000, 6 functional), and Shin Nakamura Chemical Industries, Ltd .: U15HA (weight average molecular weight 2300, 15 functional), U-6LPA (weight average molecular weight 800, hexafunctional) And the like can be given.

  As the polymerizable compound, a fluorine-containing polymerizable compound containing one or more fluorine atoms in one molecule, a silicone-based polymerizable compound having one or more siloxane bonds in one molecule, and the like can also be used. As the fluorine-containing polymerizable compound, for example, various compounds described in paragraphs 0077 to 0103 of JP2013-130865A can be used. On the other hand, as for the silicone-based polymerizable compound, JP-A-2013-130865, paragraph 0141 and JP-A-2012-103689, 0119-0120 can be referred to.

  As described above, the polymerizable compound may be a monofunctional polymerizable compound. The monofunctional polymerizable compound is not particularly limited. For example, a monofunctional (meth) acrylate compound described in WO2012 / 0777807A1 paragraph 0022, a monofunctional polymerizable compound having only one vinyl bond per molecule described in JP2008-17895A, paragraph 2008 A monofunctional radically polymerizable monomer described in paragraph 0022 of JP-A-119684 can be used.

<Optional component>
The said polymer film should just be a limit which contains the component A demonstrated above, and the component B by the distribution described previously, and can contain one or more other components arbitrarily. About these components, the composition which can be used for manufacture of the said polymer film is mentioned later. The polymer film contains at least cellulose acylate as a polymer that is a component of the film, but may optionally contain one or more other polymers as long as the distribution of component A and component B described above is satisfied. It may be. Such a polymer is not particularly limited, and examples thereof include various polymers that are generally known as constituents of polymer films.

<Thickness of polymer film>
The thickness of the polymer film may be determined according to the application and is not particularly limited. The thickness of the polymer film is, for example, 20 μm or more and 80 μm or less, but may be a thickness outside this range. The thickness of the polymer film can be adjusted according to the film forming conditions.

[Laminated film]
The laminated film according to one embodiment of the present invention includes the polymer film and an adjacent layer adjacent to the second surface of the polymer film. The adjacent layer is a cured layer formed by curing the polymerizable composition.

  The polymer film contained in the laminated film is as described above.

(Adjacent layer)
The adjacent layer is a cured layer formed by curing the polymerizable composition. Here, “adjacent” with respect to adjacent layers means that they are adjacent directly or indirectly. That is, the adjacent layer may be laminated in direct contact with the second surface of the polymer film according to one embodiment of the present invention without interposing another layer, and indirectly through another layer such as a known adhesive layer. May be laminated. As described above, the high concentration region of component B exists on the other surface side where the adjacent layer (cured layer) is formed, so that one side of the polymer film can be formed without forming a cured layer on each side. By forming the cured layer only on the (second surface side), a laminated film in which curling is suppressed can be obtained.

  The adjacent layer is preferably formed using various polymerizable compositions capable of forming a hardened layer generally called a hard coat layer. The polymerizable composition for forming the adjacent layer (polymerizable composition for forming the adjacent layer) includes at least a polymerizable compound, and includes one or more optional components such as a polymerization initiator, an additive such as a filler, and a solvent. be able to. Although the thickness of an adjacent layer is not specifically limited, From viewpoints, such as transparency of a laminated film and durability, Preferably it is the range of 0.1-6 micrometers, More preferably, it is the range of 3-6 micrometers. is there. In addition, in this invention and this specification, the thickness of the layer laminated | stacked on a polymer film shall be a value calculated | required with the following method. Ten sample pieces are produced by cutting the laminated film. Cutting can be performed using a microtome. Each produced sample piece is observed with an optical microscope at a magnification of 1000 times, and the thickness of the adjacent layer is measured. The arithmetic average value of the thicknesses measured for 10 sample pieces is taken as the thickness of the adjacent layer. The adjacent layer may be a single layer or may have a laminated structure of two or more layers. Regarding the adjacent layer in which two or more layers are laminated, the thickness means the total thickness of the laminated layers.

  As the polymerizable compound contained in the polymerizable composition for forming the adjacent layer, various polymerizable compounds exemplified above as the polymerizable compound contained as the component B in the polymer film can be used. Details of the polymerizable composition for forming the adjacent layer will be described later.

(Visible light transmittance of laminated film)
In the laminated film, one outermost surface may be the first surface of the polymer film, and the other outermost surface may be the surface of the adjacent layer. Thus, the laminated film which provided the adjacent layer (cured layer) only on the single side | surface side of the polymer film can show a high visible light transmittance compared with the laminated film which has a hardened layer on both surfaces side, respectively. In the present invention and the present specification, the visible light transmittance means a transmittance measured using a spectrophotometer at a measurement wavelength of 550 nm. A known spectrophotometer can be used as the spectrophotometer. The laminated film preferably has a visible light transmittance of 90% or more. The visible light transmittance is, for example, 98% or less, but is preferably as high as possible, and may be more than 98%.

  Next, a manufacturing method suitable as a manufacturing method of the laminated film according to one embodiment of the present invention will be described. However, the laminated film was produced by any production method as long as it had the polymer film detailed above and had an adjacent layer (cured layer) adjacent to the second surface of the polymer film. It may be a thing.

[Production method of laminated film]
A further aspect of the present invention is a method for producing a laminated film according to one aspect of the present invention described above, the first composition comprising cellulose acylate, a polymerizable compound and an organic solvent, and cellulose acylate. And an organic solvent, and when a polymerizable compound is contained, a cast film is formed by co-casting with the second composition containing the polymerizable compound at a concentration lower than the polymerizable compound concentration of the first composition. Applying the polymerization treatment to the cast film formed, applying the polymerizable composition for forming the adjacent layer to the second composition side surface before or after applying the polymerization treatment to the cast film, In addition, the present invention relates to a method for producing the laminated film, comprising subjecting the polymerization composition for forming an adjacent layer to polymerization.
Hereinafter, the manufacturing method will be described in more detail.

<Composition used for co-casting>
(First composition)
The first composition is a polymerizable composition containing a polymerizable compound, and contains at least cellulose acylate and an organic solvent together with the polymerizable compound. Details of the cellulose acylate and the polymerizable compound are as described above.

-Organic solvent-
As the organic solvent contained in the first composition, an organic solvent generally used for casting film formation can be used without any limitation. In one embodiment, examples of organic solvents include ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, tetrahydrofuran (THF), 1,4-dioxane, 1,3-dioxolane, 1,2-dimethoxyethane, and the like. Ethers, methyl formate, ethyl formate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, and other esters, methyl cellosolve, dimethylimidazolinone, dimethylformamide, dimethylacetamide, acetonitrile, dimethyl sulfoxide, sulfolane, Examples thereof include nitroethane, methylene chloride (methylene chloride), methyl acetoacetate and the like. 1,3-dioxolane, THF (tetrahydrofuran), methyl ethyl ketone, acetone, methyl acetate and methylene chloride are preferred. In the mixed solvent in which two or more kinds of solvents are mixed, the organic solvent exemplified above is the main solvent occupying the largest proportion (for example, 50% by mass or more and less than 99% by mass with respect to 100% by mass of the mixed solvent). Is preferred.

  As the organic solvent (subsolvent) contained in the mixed solvent together with the main solvent, alcohol having 1 to 4 carbon atoms is preferable. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and propylene glycol monomethyl. One type or two or more types of ethers can be mentioned. The auxiliary solvent can be contained in the mixed solvent in a proportion of, for example, 1% by mass to less than 50% by mass, preferably 1% by mass to 40% by mass with respect to 100% by mass of the total amount of the mixed solvent. The first composition may contain a small amount of water in addition to the organic solvent. When water is included, the content of water with respect to 100% by mass of the solvent is, for example, 0.1 to 5% by mass, preferably 0.1 to 3% by mass, and more preferably 0.2 to 2% by mass. it can.

  When the total amount of the first composition is 100% by mass, the ratio of the total amount of the solvent is, for example, in the range of 60 to 95% by mass, and preferably in the range of 70 to 85% by mass. A composition containing a solvent in the above range is preferable because it hardly causes a change in concentration and composition due to volatilization of the solvent and precipitation of solids, and a viscosity suitable for stable casting is obtained.

  The cellulose acylate content in the first composition is, for example, in the range of 10 to 50% by mass, with the total amount of the first composition being 100% by mass. On the other hand, the content of the polymerizable compound in the first composition can be in the range of 0.5 to 10.0, for example, with the cellulose acylate content as 1.0 on a mass basis. Adjustment of the content of the polymerizable compound and cellulose acylate in the first composition can also be mentioned as one of means for controlling the distribution of component A and component B as described above. For example, as the content of the polymerizable compound in the first composition is increased, the content of component B in the surface layer portion on the first surface side of the polymer film to be formed tends to increase. Moreover, since the ratio for which a cellulose acylate accounts in a 1st composition falls relatively by this, the component A content rate in the surface layer part by the side of the 1st surface of the polymer film formed tends to fall. Conversely, as the cellulose acylate content in the first composition is increased, the content of component A in the surface layer portion on the first surface side of the formed polymer film tends to increase. Moreover, since the ratio for which a polymeric compound accounts in a 1st composition by this falls relatively, the component B content rate in the surface layer part by the side of the 1st surface of the polymer film formed tends to fall.

-Optional component-
In addition to the said component, a 1st composition can contain 1 or more types of the well-known component generally used for preparation of a polymer film in arbitrary ratios. Examples of such components include known plasticizers, polymerization initiators, surfactants, matting agents, etc., but are not limited to these, and physical properties required according to the use of the polymer film. Based on this, the components and content contained in the first composition can be determined. In addition, the polymerization process of a polymeric compound can be performed by light irradiation, heating, etc. according to the kind of polymeric compound. Depending on the components used in combination, active species may be generated by light irradiation or heating, and this active species may exert an action of initiating polymerization of the polymerizable compound. In such a case, the first composition may not contain a polymerization initiator. As an example, cellulose acylate may generate radicals by light irradiation. In such a case, at least light irradiation is performed using a polymerizable compound and cellulose acylate in combination without using a polymerization initiator. Polymerization treatment of a polymerizable compound can also be performed by polymerization treatment. In addition, the polymerizable compound may generate radicals by heating. In such a case, the polymerizable compound can be polymerized by at least heating polymerization without using a polymerization initiator. .

-Solid content concentration-
In this invention and this specification, solid content concentration means the ratio for which the sum total of all components other than a solvent accounts with respect to 100 mass% of composition whole quantity. What is necessary is just to determine solid content concentration of a 1st composition considering application | coating aptitude, for example, it is the range of 5-40 mass%, Preferably it is the range of 15-30 mass%. The same applies to the solid content concentration of the second composition described later.

(Second composition)
The first composition described above is co-cast with the second composition (also called multi-layer simultaneous casting). In co-casting, it is easy to give a difference in composition and physical properties between the surface layer part on one surface side and the surface layer part on the other surface side by changing the composition of the composition used for co-casting. It is preferable. The second composition used for co-casting with the first composition is a composition having a lower concentration of polymerizable compound than the first composition. For example, the cellulose described above for the first composition Regarding the ratio of the amount of the polymerizable compound to the acylate, a composition having a ratio difference of 0.5 or more is more preferable, and a composition containing no polymerizable compound is more preferable. Here, “does not contain” means that it is not actively added as a component for preparing the composition.

  About the detail of a 2nd composition, the above-mentioned description regarding a 1st composition is applicable except the density | concentration of a polymeric compound.

<Formation of casting film by co-casting>
Production of a casting film by co-casting the first composition and the second composition can be performed by a known casting film forming method. As an example, reference can be made to FIGS. 3 and 4 of JP2012-96523A and the description of these drawings in the same publication. However, it is not limited to the mode described in JP 2012-96523 A, and a known casting film forming method can be used without any limitation. According to co-casting, a casting film is usually formed by casting a co-casting composition (also called a dope) on a support, and the formed casting film is subjected to various treatments such as drying and polymerization. By performing the treatment, a polymer film can be produced. For example, a co-casting composition (dope) is cast on a traveling casting film-forming support (for example, a band or a drum) and subjected to various treatments while traveling with the support, at an appropriate time. Remove from the support. The casting film can be subjected to a drying treatment before peeling off from the support, after peeling from the support, or at both times. The drying process can be performed by placing in a heating furnace, conveying in the heating furnace, blowing hot air, or the like. The heating temperature at the time of drying is preferably set to a temperature at which the polymerization reaction of the polymerizable compound does not progress and the cellulose acylate does not undergo large heat shrinkage. From the above points, the heating temperature during drying is preferably 70 ° C or higher, and more preferably 80 ° C or higher. Here, the heating temperature refers to the temperature of warm air or the atmospheric temperature in the heating furnace. On the other hand, by increasing the heating temperature, the polymerizable compound tends to be unevenly distributed on the first surface side in the cast film, and the content of cellulose acylate on the first surface side tends to decrease relatively. We believe that there is. Therefore, as described above, the means for controlling the distribution of the component A and the component B can include controlling the heating temperature. From the viewpoint of controlling the distribution of component A and component B, the heating temperature is preferably 120 ° C. or lower, and more preferably 110 ° C. or lower.

  Further, as described above, as means for controlling the distribution of component A and component B, in the co-casting, the coating amount (the set film thickness during casting) of the first composition and the second composition is set. The adjustment can also be mentioned.

  The polymerization treatment can be performed on the casting membrane at an arbitrary time, for example, on the casting membrane after being peeled off from the support. The polymerization treatment can be performed by light irradiation, heating, or the like. From the viewpoint that the polymerization reaction proceeds at an early stage, it is preferable to perform polymerization treatment (photopolymerization) by light irradiation.

As a light source for light irradiation, for example, a UV (Ultra Violet) light source capable of irradiating ultraviolet rays can be used, but it is not particularly limited. Specific examples include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a carbon arc, a metal halide lamp, and sunlight. Moreover, light irradiation conditions are not specifically limited, What is necessary is just to determine according to the kind of polymeric compound. As an example, the photopolymerization by ultraviolet irradiation can set the irradiation amount of ultraviolet rays to about 10 to 2000 mJ / cm ² , for example. In addition, the ultraviolet-ray (ultraviolet light) in this invention and this specification shall mean the light of the wavelength range of 200-400 nm. Further, in the present invention and the present specification, the cast film refers to a film original fabric in a wet state to a dry state, regardless of whether a solvent is contained or whether a polymerizable compound contained is polymerized. .

  On the other hand, the thermal polymerization is preferably performed by a heat treatment in which the cast film is heated at a heating temperature in the range of 100 to 200 ° C. for 2 to 200 minutes. In addition, in this invention and this specification, the heating temperature regarding a cast film shall mean the temperature of the cast film currently heated. Further, the cast film may be heated while traveling, or may be heated in a stopped state. From the viewpoint of productivity, the cast film is usually heated while running. Further, the heat treatment is not limited to that for the web form. For example, the heat treatment may be performed on the sheet punched from the web form in the above temperature range and time range.

  In co-casting, a cast film in which a coating layer of the first composition and a coating layer of the second composition are laminated is obtained, and during casting, between the coating layers or inside each coating layer. It is thought that the concentration distribution of each component is brought about in the cast film by the diffusion of the component. In addition to this, as described above, the distribution of component A and component B in the resulting polymer film can be controlled by the molecular weight of the polymerizable compound, the heating temperature during drying of the cast film, and the like. Conceivable. In co-casting, the thickness of the coating layer of the first composition and the coating layer of the second composition takes into consideration the difference in the formulation and formulation of each composition, the thickness of the polymer film to be produced, etc. You only have to set it. In addition, at least two types of compositions having different compositions may be used for co-casting, and it is also possible to co-cast compositions of three or more layers having different compositions.

<Formation of adjacent layer (cured layer)>
The said adjacent layer can be formed by apply | coating the polymeric composition for adjacent layer formation to the 2nd composition side surface of the formed cast film, and performing a polymerization process to this composition. In one aspect, the cast film can be polymerized in the polymerization process of the adjacent layer forming polymerizable composition. In this aspect, an aspect in which the casting film is not subjected to the polymerization treatment before application of the adjacent layer forming composition and a part of the process is adjacent when the casting film is subjected to the polymerization treatment in two or more steps. The remaining steps of the casting film polymerization process may be performed before the application of the layer forming composition and by the polymerization process of the adjacent layer forming composition. Or as another one aspect | mode, after performing a superposition | polymerization process to a cast film, application | coating of the composition for adjacent layer formation and a superposition | polymerization process can also be performed.

  From the viewpoint of improving the adhesion between the polymer film and the adjacent layer (cured layer) in the laminated film, the former mode is preferable among the above two modes. By applying the polymerizable composition for forming the adjacent layer in a state where all or part of the polymerizable compound contained in the cast film is unpolymerized, and then performing a polymerization treatment, the polymerizability contained in the cast film This is because it is considered that the polymerizable compound contained in the coating layer of the compound and the polymerizable composition for forming the adjacent layer can cause a polymerization reaction in the vicinity of the interface between the cast film and the coating layer. In this way, the polymerization reaction takes place near the interface between the cast film and the coating layer of the polymerizable composition for forming the adjacent layer, so that the resulting laminated film has a crosslinked structure near the interface between the polymer film and the adjacent layer. The present inventors presume that the ability to form the film contributes to improving the adhesion. However, this is merely a guess and does not limit the present invention.

  Application | coating of the polymeric composition for adjacent layer formation can be performed to the 2nd composition side surface of a cast film directly or via other layers, such as a well-known contact bonding layer. In the former aspect described above, it is preferable to apply the adjacent layer forming composition directly to the second composition side surface of the cast film. The coating can be performed by a known coating method such as a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a die coating method, a wire bar coating method, or a gravure coating method. What is necessary is just to adjust the application quantity to the quantity which can form the adjacent layer (hardened layer) of desired thickness. In addition, an adjacent layer can also be formed as a hardened layer of a laminated structure of two or more layers (for example, about two to five layers) by simultaneously or sequentially applying compositions of two or more different compositions.

  The polymerization treatment applied to the polymerizable composition for forming an adjacent layer can be performed by light irradiation and heating. What is necessary is just to set suitably the conditions of these polymerization processes according to the kind etc. of component contained in the polymeric composition for adjacent layer formation. As described above, it is preferable to perform polymerization treatment (photopolymerization) by light irradiation in that the polymerization reaction proceeds at an early stage.

  By the process demonstrated above, the laminated | multilayer film concerning 1 aspect of this invention which has an adjacent layer (hardened layer) in the 2nd surface side of the polymer film concerning 1 aspect of this invention can be obtained. The laminated film is suitable as a protective film for various uses. As a specific aspect, the aspect which applied the said laminated | multilayer film to the polarizing plate and the image display apparatus is demonstrated below.

[Polarizer]
A further aspect of the present invention relates to a polarizing plate comprising at least the above laminated film and a polarizer adjacent to the first surface of the polymer film contained in the laminated film.
Hereinafter, the polarizing plate will be described in more detail.

  In the polarizing plate, usually, a polarizer is disposed between two protective films (polarizing plate protective film). The laminated film can be at least one or both of two protective films. And a polarizer and the 1st surface of the said polymer film adjoin. Therefore, in the said polarizing plate, a polarizer, the said polymer film, and an adjacent layer are located in this order. In the liquid crystal display device, usually, two polarizing plates (viewing side polarizing plate and backlight side polarizing plate) are arranged with a liquid crystal cell interposed therebetween. The polarizing plate according to one embodiment of the present invention may be used for any of the two polarizing plates. In one embodiment, the polarizing plate can be used as a viewing-side polarizing plate. One of the two protective films included in the viewing side polarizing plate is disposed on the viewing side, and the other is disposed on the liquid crystal cell side. In this case, the said laminated | multilayer film may be used for any of a visual recognition side protective film and a liquid crystal cell side protective film, and can be used as a visual recognition side protective film in one aspect | mode.

  As the polarizer contained in the polarizing plate, one obtained by immersing and stretching a polyvinyl alcohol film in an iodine dyeing solution can be used. Hereinafter, such a polarizer is also referred to as a polyvinyl alcohol polarizer or an iodine dyed polyvinyl alcohol polarizer. JP, 2011-136503, A paragraph 0117 can be referred to for the details of a polarizer, for example.

  “Adjacent” for the polarizer and the first surface of the polymer film also means directly or indirectly adjacent. That is, the polarizer may be laminated in direct contact with the first surface of the polymer film according to one embodiment of the present invention without any other layer, and indirectly through another layer such as a known adhesive layer. May be laminated. For example, the polyvinyl alcohol polarizer is bonded to the first surface of the polymer film while spraying water on the surface of the polyvinyl alcohol polarizer, thereby making use of the so-called water action of polyvinyl alcohol. Can be bonded to a polymer film. Alternatively, the polarizer and the first surface of the polymer film can be bonded together via an adhesive layer. As an adhesive for forming the adhesive layer, it is cured by irradiation with an aqueous solution of polyvinyl alcohol or polyvinyl acetal (for example, polyvinyl butyral), latex of vinyl polymer (for example, polybutyl acrylate), active energy rays or heating. A curable adhesive composition containing an epoxy compound can be used. A preferred adhesive is an aqueous solution of polyvinyl alcohol, and a more preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol. In such bonding, the presence of 10% by mass or more of cellulose acylate on the first surface (surface layer portion on the first surface side) that becomes the bonding surface improves adhesion with the polarizer (separation due to this). The present inventors speculate that this contributes to (suppression).

  In addition, the presence of cellulose acylate in the first surface side surface layer portion of the polymer film is also preferable in that the first surface becomes a saponifiable surface. By subjecting the first surface to saponification and saponifying cellulose acylate, the adhesion to the polarizer can be further improved. On the other hand, in a polymer film having a cured layer on each side, it is usually difficult to saponify the surface of the cured layer and improve the adhesion to the polarizer (polarizer layer). For the saponification treatment, a known technique can be applied without any limitation. The saponification treatment can be performed, for example, in a cycle in which the first surface is immersed in an alkaline solution, neutralized with an acidic solution, washed with water and dried. As for the saponification treatment, for example, paragraphs 0211 to 0212 of JP-A-2007-86748 can be referred to.

  In one embodiment, one of the two protective films included in the polarizing plate can be the laminated film, and the other can be an optical compensation film. A known film can be used as the optical compensation film.

By the way, in general, the iodine-stained polyvinyl alcohol-based polarizer tends to cause light leakage over time due to the influence of moisture (humidity) in a use atmosphere or a storage atmosphere (low polarizing plate durability). This is presumably due to the following reasons. The iodine-stained polyvinyl alcohol polarizer usually contains a complex of a component derived from an iodine staining solution and polyvinyl alcohol (hereinafter referred to as “iodine complex”). It is considered that this iodine-based complex contributes to exhibiting polarization characteristics in which a polarizer selectively allows only light having a polarization plane in a certain direction to pass through. Here, the decomposition of the iodine-based complex due to the effect of moisture, and the release of iodine ions and iodine molecules generated by the decomposition out of the polarizer cause a decrease in the polarization characteristics of the polarizer. It is thought that leakage will occur. Note that the degree of light leakage with time (polarizing plate durability) can be evaluated by the amount of change in orthogonal transmittance at a wavelength of 410 nm shown in Examples described later. The higher the orthogonal transmittance at the wavelength of 410 nm, the more light leaks around the wavelength of 410 nm, which means that the black display becomes blue in an image display device such as a liquid crystal display device. Therefore, from the viewpoint of maintaining good color reproducibility of the image display device over time, the amount of orthogonal transmittance at a wavelength of 410 nm is preferably small.
In order to improve the polarizing plate durability of the iodine-stained polyvinyl alcohol polarizer described above, it is preferable to provide a polarizing plate protective film on one or both of the polarizers. Further, in this regard, the present inventors, as an unexpected phenomenon, have the polarizing plate durability by using the laminated film as a protective film for one or both of the polarizing plates with the first surface adjacent to the polarizer. We have newly found that it is possible to improve the performance. This is because the polymer film contained in the laminated film contains component B together with component A (cellulose acylate), and the content of component B on the first surface of the polymer film adjacent to the polarizer is 30% by mass or more. The present inventors speculate that this is due to a certain reason. Specifically, the present inventors consider that inclusion of component B in the polymer film contributes to suppressing moisture from entering the polarizer. Moreover, the content rate of the component B in the 1st surface of the polymer film adjacent to a polarizer is 30 mass% or more, and the iodine ion and iodine molecule which were produced | generated by decomposition | disassembly of an iodine type complex are discharge | released out of a polarizer. The present inventors consider that it contributes to suppression of being done. From this point, the content of component B in the surface layer portion on the first surface side of the polymer film is preferably 40% by mass or more, more preferably more than 50% by mass, and 55% by mass or more. Is more preferably 60% by mass or more, and the higher the content, the more preferable.
However, the above is an inference by the present inventors and does not limit the present invention.

[Image display device]
The further aspect of this invention is related with the image display apparatus containing at least 1 chosen from the group which consists of the said laminated | multilayer film and the said polarizing plate.

  In one aspect | mode, the said laminated | multilayer film can be protective films arrange | positioned in arbitrary positions of an image display apparatus, such as a protective film arrange | positioned on the display surface outer side of an image display apparatus.

  The specific aspect of the arrangement of the polarizing plate in the image display device including the polarizing plate is as described above.

  Examples of the image display device include various image display devices such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display device (CRT).

  In one embodiment, the image display device can be a liquid crystal display device including a polarizing plate as an essential constituent member. The liquid crystal cell of the liquid crystal display device has various drive modes such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, OCB (Optically Compensated Bend) mode, IPS (In Plane Switching) mode, ECB (Electrically Controlled Birefringence) mode, etc. Liquid crystal cell.

  For other details regarding the image display device, known techniques can be applied without any limitation.

Hereinafter, the present invention will be described more specifically based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.
Moreover, in the evaluation of the polymer films and laminated films prepared in the following examples and comparative examples, a 20 cm square film was cut out from a position 1 cm or more away from each outer side surface of the film, and used as a measurement sample.
The total thickness of the polymer film is 9 of the line that equally divides the length and width of the measurement sample cut out as described above from the polymer film before forming the adjacent layer (cured layer) into 4 equal portions at 5 cm intervals in the examples and comparative examples. One lattice point was taken as a measurement location, and an arithmetic average value of values measured by a stylus film thickness meter at each measurement location was obtained.
The thickness of the adjacent layer (cured layer) was determined by the method described above using the measurement sample.
The temperature of the casting film in the co-casting (casting film forming process) described below was monitored with a non-contact thermometer.

[Example 1]
<Preparation of first composition (polymerizable compound-containing cellulose acylate dope A)>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare Dope A.
――――――――――――――――――――――――――――――――――――――
(Solid content)
Cellulose acetate (acetyl substitution degree 2.86, polymerization degree 350) 100 parts by mass polymerizable compound 1 100 parts by mass (10 functional urethane acrylate (manufactured by Nippon Synthetic Chemical Co., Ltd. UV-1700B))
Photopolymerization initiator 2.5 parts by mass
Solid content concentration (based on 100% by mass of the total composition) 24% by mass
(Solvent composition ratio: the content in parentheses is 100 parts by mass of cellulose acetate with respect to 100% by mass of the total amount of solvent)
Methylene chloride 79% by mass (500 parts by mass)
Methanol 20% by mass (127 parts by mass)
1-butanol 1% by mass (6 parts by mass)
――――――――――――――――――――――――――――――――――――――

<Preparation of second composition (cellulose acylate dope B)>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare Dope B.
――――――――――――――――――――――――――――――――――――――
(Solid content)
Cellulose acetate (substitution degree 2.86, polymerization degree 350)
Solid content concentration (based on 100% by mass of the total composition) 24% by mass
(Solvent composition ratio: the content in parentheses is 100 parts by mass of cellulose acetate with respect to 100% by mass of the total amount of solvent)
Methylene chloride 79% by mass (625 parts by mass)
Methanol 20% by mass (158 parts by mass)
1-butanol 1% by mass (8 parts by mass)
――――――――――――――――――――――――――――――――――――――

<Polymer film casting>
As the casting die, the casting die having the configuration shown in FIG. 1 was used. The film forming apparatus used in Example 1 includes a casting drum (drum support), and the film peeled off from the casting drum is conveyed to a drying chamber (heating chamber) and heated. An open system was used except for the drying room. The heating time was controlled by changing the transport distance of the drying chamber. The casting die 21 shown in FIG. 1 joins the flow of the dope a and the flow of the dope b, and then flows out from the discharge port on the tip onto the casting drum 22 to thereby apply the coating layer derived from the dope a. The casting film 40 is formed as a laminate of the coating layer 40b derived from 40a and the dope b.
The dopes A and B prepared above are used in order of the dopes A and B from the air surface side to the support side using the dope A as the dope a and the dope B as the dope b shown in FIG. The flow rate was adjusted to correspond to the film thickness (set film thickness) shown in Table 1, and the cast film was formed by co-casting from a casting die onto a drum support having a surface temperature of 5 ° C. Thereafter, 40 ° C. dehumidifying air was applied on the drum support to peel off the cast film from the drum support.
Drying air was applied to the running cast film in a drying chamber and heated at the temperature and time indicated in the drying conditions in Table 1 to dry the solvent (drying treatment).

<Preparation of polymerizable composition for forming adjacent layer>
The following composition was placed in a mixing tank, stirred, and filtered through a polypropylene filter having a pore size of 0.4 μm to prepare an adjacent layer forming polymerizable composition HC1 (solid content concentration: 58 mass%).
――――――――――――――――――――――――――――――――――――――
Solvent: Methyl acetate 21 parts by mass Methyl ethyl ketone (MEK) 21 parts by mass Polymerizable compound 56.26 parts by mass (3.4 functional acrylate (Nippon Kayaku KAYARAD PET30))
Photopolymerization initiator: 1.74 parts by mass
(IRGACURE184 manufactured by BASF)
――――――――――――――――――――――――――――――――――――――

<Preparation of adjacent layer>
The composition HC1 is applied to the surface of the second composition (dope B) side of the cast film after drying (polymer film containing a polymerizable compound before polymerization) using a gravure coater, and a coating layer is formed. Formed (solid content application amount: 12.1 g / m ² ). After drying the coating layer formed in a heating furnace having a furnace atmosphere temperature of 100 ° C., a 160 W / cm air-cooled metal halide lamp (eye graphic) is purged with nitrogen so that the atmosphere has an oxygen concentration of 1.0% by volume or less. Using an ultraviolet ray having an illuminance of 400 mW / cm ² and an irradiation amount of 150 mJ / cm ² , the coating layer is polymerized and cured to form an adjacent layer (cured layer). A laminated film of the film was obtained. In the present embodiment, the polymerization treatment is performed on the polymerizable compound contained in the cast film (polymer film) by the polymerization treatment of the coating layer.

  In Table 1, the manufacturing process performed in Example 1 is described as manufacturing process A.

[Examples 2 and 3]
A laminated film was obtained in the same manner as in Example 1 except that the cellulose acetate content of dope A was changed to the amount shown in Table 1.

[Examples 4 to 7]
A laminated film was obtained in the same manner as in Example 1 except that the set film thickness of dope A and the set film thickness of dope B in co-casting were changed to the set film thicknesses shown in Table 1.

[Examples 8 to 13]
A laminated film was obtained in the same manner as in Example 1 except that the following polymerizable compound was used in place of the polymerizable compound 1 as the polymerizable compound of the dope A.
Polymerizable compound 2: U15HA manufactured by Shin-Nakamura Chemical Co., Ltd.
Polymerizable compound 3: DPCA30 manufactured by Nippon Kayaku Co., Ltd.
Polymerizable compound 4: Nippon Kayaku Co., Ltd. DPCA60
Polymerizable compound 5: DPCA120 manufactured by Nippon Kayaku Co., Ltd.
Polymerizable compound 6: DPHA manufactured by Nippon Kayaku Co., Ltd.
Polymerizable compound 7: Shin-Nakamura Chemical Co., Ltd. A-TMMT

[Examples 14 and 15]
A laminated film was obtained in the same manner as in Example 1 except that the running cast film was heated in the drying chamber in the drying chamber at the temperature and time shown in the drying conditions in Table 1 to dry the solvent.

[Example 16]
The photoinitiator in Example 1 was changed to a thermal initiator (2,2′-azobisisobutyronitrile), and the running film was subjected to drying air in a drying chamber to the drying conditions shown in Table 1. A laminated film was obtained in the same manner as in Example 1 except that the film was heated at the indicated temperature and time, and the solvent was dried and the polymerization initiator was polymerized (thermal polymerization).

  In Table 1, the manufacturing process performed in Example 16 is referred to as manufacturing process B.

[Example 17]
After performing the casting film drying process in the same manner as in Example 1, in the drying chamber where the drying process was performed, 160 W / cm while purging with nitrogen so that the atmosphere had an oxygen concentration of 1.0 vol% or less. Using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the surface of the first composition side is irradiated with ultraviolet rays having an illuminance of 400 mW / cm ^{2 −} and an irradiation amount of 300 mJ / cm ² to perform polymerization treatment of the polymerizable compound. A laminated film was obtained in the same manner as in Example 1 except for the above points.

  In Table 1, the manufacturing process performed in Example 17 is described as manufacturing process C.

[Comparative Example 1]
A laminated film was obtained in the same manner as in Example 1 except that the dope A was changed to the dope B (that is, the dope B was used as a dope casted on the air surface side).

[Comparative Example 2]
A laminated film was obtained in the same manner as in Example 1 except that the dope B was changed to the dope A (that is, the dope A was also used as the dope casted on the support side).

[Comparative Example 3]
A laminated film was obtained in the same manner as in Example 1 except that the polymerizable compound content of the dope A was changed to the amount shown in Table 1.

[Comparative Example 4]
After performing the casting film drying process in the same manner as in Comparative Example 1, the composition HC1 was applied to the surface of the cast film after the drying process on the first composition (dope A) side using a gravure coater. A coating layer was formed (solid content coating amount: 12.1 g / m ² ). After drying the coating layer formed in a heating furnace having a furnace atmosphere temperature of 100 ° C., a 160 W / cm air-cooled metal halide lamp (eye graphic) is purged with nitrogen so that the atmosphere has an oxygen concentration of 1.0% by volume or less. By using an ultraviolet ray having an illuminance of 400 mW / cm ² and an irradiation amount of 150 mJ / cm ² , polymerizing the applied layer and curing it, and adjacent to the first composition (dope A) side surface A layer (cured layer) was formed. Then, the adjacent layer was formed in the surface similar to Example 1 at the 2nd composition (dope B) side surface. Thus, a laminated film having adjacent layers (cured layers) on both sides of the polymer film was obtained.

[Evaluation method]
<Composition analysis by Raman spectroscopy>
The composition analysis of the polymer film was performed using a confocal Raman microscope (manufactured by Tokyo Instruments: NanoFinder 30). The excitation wavelength was 785 nm, the laser power was 18 mW, and a 100 × objective lens was used. The integration time was 120 seconds.
Three cut surfaces obtained by cutting the measurement sample at intervals of 5 cm in the measurement sample of 20 cm square cut out as described above from the polymer film before forming the adjacent layer (cured layer) in Examples and Comparative Examples The measurement positions in the thickness direction were determined at intervals of 5 cm. Nine measurement positions are thus determined. At each measurement position, composition analysis was performed by Raman spectroscopy (microscopic Raman spectroscopy) using the Raman microscope at a measurement location at an interval of 0.50 μm in the film thickness direction from the air surface side surface during casting. The contents of component A (cellulose acetate) and component B (a component selected from the group consisting of the polymerizable compound and a polymer of the polymerizable compound) were measured. Of the surface layer portion on the first surface side (air layer side in casting), the surface layer portion on the second surface side (support side in casting) and the central component A and component B determined by the method described above Table 1 shows the respective contents.
As an example, the graph which shows the content rate change of the component A in the thickness direction of the polymer film obtained about Example 1 and the component B is shown in FIG.
About Examples 1-15 and Comparative Examples 1-4, the polymer film which performed the composition analysis is a polymer film containing the polymeric compound after a drying process and before a polymerization process. Since the distribution of each component in these polymer films is considered to be unchanged before and after the polymerization treatment (ultraviolet irradiation), the distribution of each component in the polymer film contained in the laminated film obtained by forming the adjacent layer is also described above. It can be regarded as the same distribution as obtained by composition analysis.
On the other hand, for Example 16, the polymer film subjected to composition analysis is a polymer film that has been subjected to a polymerization treatment (thermal polymerization) of a polymerizable compound during the drying treatment. About Example 17, the polymer film which performed the composition analysis is a polymer film by which the polymerization process of the polymeric compound was performed by the ultraviolet irradiation after a drying process.
In Table 1, the air surface side during casting of the polymer film is referred to as a first surface, and the support surface side is referred to as a second surface. About the polymer film produced in the Example, it was confirmed by the said compositional analysis that the air surface side at the time of casting is the 1st surface, and the support body side is the 2nd surface. Moreover, in the polymer film produced by the Example by the said composition analysis, the component A and the component B may exist also in the area | region between the surface layer part of the 1st surface side, and the surface layer part of the 2nd surface side. confirmed.

<Curl evaluation of laminated film>
The curl evaluation of the laminated films of Examples and Comparative Examples was performed according to the measuring method prescribed by the American National Standards Institute (ANSI / ASC PH 1.29-1985, Method A). Specifically, a film sample obtained by cutting each laminated film into a rectangular shape of 3 mm × 35 mm is set so that the film sample does not protrude from a column that is perpendicular to the curl plate and set, and the temperature is 25 ° C., the relative humidity is 60%, The humidity was adjusted for 10 hours. After humidity control, it is read to which memory of the curl plate the tip of the film sample is curled. The value read here is generally called an F-type curl value. Hereinafter, it is simply referred to as a curl value. At this time, the curl value measured according to the direction in which the film sample curls becomes a positive or negative value. The larger the measured curl value, the stronger the curl.
FIG. 3 is an explanatory diagram of curl evaluation and represents an example in which the curl of a film sample is measured according to the measurement method prescribed by the American National Standards Institute. In FIG. 3, the curl of the film sample 1 has a value at the curl plate 2 of minus 0.5 or less (absolute value of 0.5 or less).
The curl of each laminated film was evaluated according to the following criteria based on the measured curl value (absolute value). Evaluation result D is a level at which it is difficult to bond the laminated film to another member.
A: 2.0 or less B: Greater than 2.0 and 4.0 or less C: Greater than 4.0 and 6.0 or less D: Greater than 6.0

<Adhesion evaluation with polarizer>
(Preparation of polarizing plate sample)
For each Example and Comparative Example, two laminated films were prepared, and the two laminated films were each subjected to saponification treatment (alkali saponification treatment) on the outermost surface on the air surface side during casting by the following method.
The outermost surface on the air surface side when the laminated film is cast is immersed in a 1.5 N (1.5 mol / L) aqueous sodium hydroxide solution having a liquid temperature of 55 ° C. for 2 minutes and washed in a water-cooled bathtub at room temperature. Neutralization was performed using 0.1 N (0.05 mol / L) sulfuric acid at a temperature of 30 ° C. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C.
Subsequently, a roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer having a thickness of 20 μm. Using a 3% by weight aqueous solution of polyvinyl alcohol (Kuraray PVA-117H) as an adhesive, the surfaces of the two laminated films subjected to alkali saponification treatment were bonded to one side and the other side of the polarizer to obtain a polarizing plate. . Bonding was performed such that the casting direction of the polymer film contained in the laminated film was parallel to the absorption axis of the polarizer.
(Evaluation of polarizing plate sample)
The polarizing plates of the examples and comparative examples were placed in an oven having a furnace atmosphere temperature of 80 ° C. for 24 hours, and then humidity-controlled for 1 hour in a room at a temperature of 25 ° C. and a relative humidity of 60%, and then a 4 cm × 4 cm Thomson blade Five sheet samples (polarizing plate samples) were obtained using a punching machine.
With respect to a polarizing plate sample having a square shape of 4 cm × 4 cm that has been punched, one sample of the degree of peeling at the interface between the polymer film and the polarizer contained in the laminated film on each side of the square is based on the following criteria: 4 points were scored with the highest score.
0.00 point: No peeling occurred.
0.25 point: The area where peeling occurs is 25% or less of one side.
0.50 point: The region where peeling occurs is from more than 25% to 50% or less on one side.
0.75 point: The region where peeling occurs is more than 50% to 75% or less on one side.
1.00 point: The area where peeling occurs is more than 75% of one side.
The scores were totaled for five polarizing plate samples and evaluated as follows.
A: 0 to 5 points B: 10 points to 5 points C: 15 points to 15 points D: 15 points to 20 points

<Visible light transmittance>
The visible light transmittance (transmittance at a wavelength of 550 nm) of the laminated films of Examples and Comparative Examples was measured with an ultraviolet-visible spectrophotometer (Shimadzu UV / vis spectrum meter U2400).

<Evaluation of adhesion between polymer film and adjacent layer>
Evaluation was performed by the cross-cut method described in JIS-K5400. That is, incisions that divide into 10 equal parts at 1 mm vertical and horizontal intervals on the surface of the adjacent layer of the laminated film obtained in Examples and Comparative Examples (for Comparative Example 4, the adjacent layer formed on the second surface side of the polymer film). After forming a total of 100 regions, an adhesion test was performed on the surface on which these regions were formed using cellophane tape (manufactured by Nichiban Co., Ltd.). In the adhesion test, the operation of peeling after applying a new cellophane tape was repeated three times at the same location. From the number of peeled areas on the surface of the adjacent layer after the adhesion test, adhesion was determined according to the following criteria.
A: The number of peeling regions is 0.
B: The number of peeling regions is 1 or more and 5 or less.
C: The number of peeling regions is 6 or more and 30 or less.
D: The number of peeling regions is more than 30.

  About each said evaluation, if it is AC among evaluation results AD, it can be judged that there is no problem practically.

  The above evaluation results are shown in Table 1.

From the results shown in Table 1, it can be confirmed that the laminated films of the examples are curled and have good adhesion between the first surface of the polymer film contained in the laminated film and the polarizer. Moreover, the laminated | multilayer film of the Example showed the high visible light transmittance compared with the laminated | multilayer film of the comparative example 4 which formed the hardened layer in both surfaces, respectively.
Furthermore, from the results shown in Table 1, it can be confirmed that the laminated films of the examples also have good adhesion to the second surface of the polymer film and the adjacent layer (cured layer) contained in this film.

<Evaluation of polarizing plate durability>
About each Example and the comparative example, the polarizing plate sample was produced by the above-mentioned method, respectively. The prepared polarizing plate samples had the laminated films of Examples and Comparative Examples on both sides of the polarizer as polarizing plate protective films, and the outermost surfaces on both sides were respectively formed on the second surface of the polymer film. It is an adjacent layer (cured layer) surface.
A sample for measuring an orthogonal transmittance (about 5 cm × 5 cm) was prepared by sticking one outermost surface (adjacent layer surface) of the polarizing plate sample to a glass plate via an adhesive (Soken Chemical SK-2057). .
The transmittance of the measurement sample thus prepared was measured in the range of 380 nm to 780 nm using an automatic polarizing film measuring device VAP-7070 manufactured by JASCO Corporation, and the transmittance at a wavelength of 410 nm was obtained as an arithmetic average value of 10 measurements. (Orthogonal transmittance, unit:%) was determined.
Thereafter, after each sample for measurement was stored for 1000 hours under an environment of an ambient temperature of 80 ° C. and a relative humidity of 90%, the orthogonal transmittance at a wavelength of 410 nm was obtained as an arithmetic average value of 10 measurements by the same method. .
The following formula:
Change in orthogonal transmittance (%) = (orthogonal transmittance determined before 1000 hours) − (orthogonal transmittance determined after 1000 hours)
Thus, the amount of change in orthogonal transmittance was calculated. From the calculated value, polarizing plate durability was evaluated according to the following evaluation criteria. The results are shown in Table 2 below.
A: Change in orthogonal transmittance is less than 0.06% B: Change in orthogonal transmittance is 0.06% or more and less than 0.08% C: Polarization change in Comparative Example 1 A plate sample differs from the polarizing plate sample of an Example by the point by which the adjacent layer (hardened layer) is laminated | stacked on the polymer film which does not contain the component B. FIG. In Comparative Example 1, the evaluation result was C, whereas in the examples, the evaluation results of A or B were obtained. Therefore, by using the laminated film of the example as a polarizing plate protective film, polarization was achieved. It was confirmed that the plate durability could be improved. In addition, although the evaluation result in Comparative Examples 2-4 is A or B, these Comparative Examples are inferior to an evaluation result in the above-mentioned evaluation item as Table 1 is made.

  The present invention is useful in the field of manufacturing various image display devices.

Claims (16)

A polymer film comprising at least component A and component B,
Component A is cellulose acylate,
The component B is one or more components selected from the group consisting of a polymerizable compound and a polymer of a polymerizable compound,
The surface layer part on the first surface side and the surface layer part on the second surface side which is the surface opposite to the first surface contain the component A and the component B, respectively.
The content of the component A in the surface layer portion on the first surface side is 10% by mass or more and the content of the component B is in the range of 40 to 80 % by mass,
The component A and the component B are also present in a region between the surface portion on the first surface side and the surface layer portion on the second surface side, and the first portion from the surface layer portion on the first surface side. The polymer film in which the content rate of the said component B falls toward the surface layer part of the 2nd surface side. 2. The polymer film according to claim 1, wherein a content ratio of the component B in the surface layer portion on the second surface side is in a range of 5 to 20 mass%. The polymer film according to claim 1 or 2 , wherein the content of the component A in the surface layer portion on the first surface side is in the range of 20 to 60 mass%. The polymer film according to any one of claims 1 to 3 , wherein a content ratio of the component A decreases from a surface layer portion on the second surface side toward a surface layer portion on the first surface side. The said cellulose acylate is a polymer film of any one of Claims 1-4 containing a cellulose acetate. The polymer film according to any one of claims 1 to 5 , wherein a molecular weight of the polymerizable compound is in a range of 250 to 3000. The polymer film according to any one of claims 1 to 6 , wherein a value obtained by dividing the molecular weight of the polymerizable compound by the number of polymerizable groups contained in one molecule is in a range of 30 to 500. The polymer film according to any one of claims 1 to 7 , wherein the polymerizable compound has a polymerizable group containing an ethylenically unsaturated bond. The polymer film according to claim 8 , wherein the polymerizable group containing an ethylenically unsaturated bond is a polymerizable group selected from the group consisting of a (meth) acryloyl group and a (meth) acryloyloxy group. A polymer film comprising at least component A and component B,
Component A is cellulose acylate,
The component B is one or more components selected from the group consisting of a polymerizable compound and a polymer of a polymerizable compound,
The polymerizable compound has a polymerizable group containing an ethylenically unsaturated bond,
The surface layer part on the first surface side and the surface layer part on the second surface side which is the surface opposite to the first surface contain the component A and the component B, respectively.
The content of the component A in the surface portion on the first surface side is 10% by mass or more and the content of the component B is 30% by mass or more,
The component A and the component B are also present in a region between the surface portion on the first surface side and the surface layer portion on the second surface side, and the first portion from the surface layer portion on the first surface side. The polymer film in which the content rate of the said component B falls toward the surface layer part of the 2nd surface side. The polymer film according to any one of claims 1 to 10, and an adjacent layer adjacent to the second surface of the polymer film, and the adjacent layer is obtained by curing the polymerizable composition. A laminated film that is a cured layer. It is a manufacturing method of the laminated | multilayer film of Claim 11, Comprising:
A first composition containing cellulose acylate, a polymerizable compound and an organic solvent; and a cellulose acylate and an organic solvent, and when containing a polymerizable compound, the concentration is lower than the polymerizable compound concentration of the first composition. Forming a cast film by co-casting with a second composition comprising a polymerizable compound at
Subjecting the cast film formed to a polymerization treatment;
Before or after applying the polymerization treatment to the casting film, applying a polymerizable composition for forming an adjacent layer to the second composition side surface; and
Subjecting the polymerization composition for forming the adjacent layer to a polymerization treatment;
The manufacturing method of the said laminated | multilayer film containing. The manufacturing method of the laminated | multilayer film of Claim 12 with which the polymerization process of the said cast film is also performed by the polymerization process performed to the said polymerizable composition for adjacent layer formation. The method for producing a laminated film according to claim 13, wherein the polymerization treatment is performed by light irradiation. A polarizing plate comprising at least the laminated film according to claim 11 and a polarizer adjacent to the first surface of the polymer film contained in the laminated film. An image display device comprising at least one selected from the group consisting of the laminated film according to claim 11 and the polarizing plate according to claim 15.