WO2023080104A1

WO2023080104A1 - Polycarbonate resin film, multilayer film, display device, polycarbonate resin film manufacturing method, and multilayer film manufacturing method

Info

Publication number: WO2023080104A1
Application number: PCT/JP2022/040642
Authority: WO
Inventors: 健小笠原; 圭佑木稲; 浩輝小高
Original assignee: 三菱瓦斯化学株式会社; Ｍｇｃフィルシート株式会社
Priority date: 2021-11-04
Filing date: 2022-10-31
Publication date: 2023-05-11

Abstract

Provided is a polycarbonate resin film comprising a constituent unit represented by formula (1), said polycarbonate resin film having uniformity of the principal axis orientation and low phase difference properties. Also provided are a multilayer film, a display device, a polycarbonate resin film manufacturing method, and a multilayer film manufacturing method. The polycarbonate resin film contains a polycarbonate resin and satisfies conditions 1-3. Condition 1: the principal constituent unit of the polycarbonate resin is the constituent unit represented by formula 1. Condition 2: deviation from the average value of the principal axis orientation angle of the film is within ±11°. Condition 3: the phase difference in the film is 5-50 nm.

Description

Polycarbonate resin film, multilayer film, display device, method for producing polycarbonate resin film, and method for producing multilayer film

The present invention relates to a polycarbonate resin film, a multilayer film, a display device, a method for producing a polycarbonate resin film, and a method for producing a multilayer film.

Conventionally, polycarbonate resin (hereinafter sometimes referred to as "PC-A") obtained by reacting 2,2-bis(4-hydroxyphenyl)propane (hereinafter sometimes referred to as "bisphenol A") with a carbonate precursor ) has been widely used as an engineering plastic in many fields because of its excellent transparency, heat resistance, mechanical properties and dimensional stability. Furthermore, in recent years, by taking advantage of its transparency, it is being used as an optical material in the fields of optical discs, films, lenses, and the like.
However, polycarbonate resin (especially PC-A) has a higher photoelastic coefficient than acrylic resin, cyclic olefin resin, etc., and is a material that easily develops retardation due to stress. When used for display front panels, etc., there was a problem that rainbow unevenness was visible when viewed with polarized sunglasses. In addition, head-up display devices, which are beginning to be installed in automobiles in recent years, require a dustproof cover to prevent dust and dirt from entering from the projection port for projecting an image from the main body of the device onto a projection part such as glass. ing. When using a cover made of polycarbonate resin, if the phase difference of the cover itself is high or the main axis orientation varies greatly, the projected image may be distorted. It was necessary to equalize the In addition, if the surface hardness of the cover itself is low, there is a problem that the surface is damaged when it comes into contact with an object with sharp edges.
Until now, it has been difficult to reduce the phase difference and make the main axis orientation uniform for polycarbonate resin films using PC-A. The above problem was solved by changing the structure of the main skeleton to make it difficult for the phase difference to occur.

Japanese Patent Application Laid-Open No. 2004-331688 JP-A-08-134199 WO2020/166408

However, reducing the retardation by changing the polymer skeleton has the problem of high development costs. That is, it would be very beneficial if a film with a low retardation could be obtained with PC-A, which has been generally used. Furthermore, in a PC-A in which it is difficult to reduce the phase difference, it would be more beneficial if the main axis orientation could be made uniform.
The present invention is intended to solve such problems, and is a polycarbonate resin film using PC-A as a raw material, which has a low retardation and a uniform main axis orientation. An object of the present invention is to provide a film, a multilayer film and a display device using the polycarbonate resin film, a method for manufacturing the polycarbonate resin film, and a method for manufacturing the multilayer film.

Based on the above problems, the present inventors have studied and found that by adjusting the method for producing a polycarbonate resin film, while using PC-A as a raw material, the polycarbonate resin film has low retardation and uniformity of the main axis orientation. succeeded in achieving
Specifically, the above problems have been solved by the following means.
<1> A polycarbonate resin film containing a polycarbonate resin and satisfying the following conditions 1 to 3;
Condition 1: Polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1);
Condition 2: the deviation from the average value of the main axis azimuth angle of the film is within ±11°;
Condition 3: The film has a retardation of 5 to 50 nm.
formula (1)

<2> The polycarbonate resin film according to <1>, wherein the polycarbonate resin film has a thickness of 50 to 1500 μm.
<3> having a polycarbonate resin film and at least one other layer,
A multilayer film that satisfies the following conditions A to C;
Condition A: Polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1);
Condition B: the deviation from the average value of the principal axis azimuth angle of the multilayer film is within ±11°;
Condition C: The retardation of the multilayer film is 5-50 nm.
formula (1)

<4> The multilayer film according to <3>, wherein the pencil hardness measured from the other layer side of the multilayer film is HB or more.
<5> The multilayer film according to <3> or <4>, wherein the polycarbonate resin film and the other layer have a total thickness of 50 to 1500 μm.
<6> The multilayer film according to any one of <3> to <5>, wherein the thickness ratio between the polycarbonate resin film and the other layer is 2/1 to 10/1.
<7> The multilayer film according to <5> or <6>, wherein the other layer has a thickness of 20 to 100 μm.
<8> The multilayer film according to any one of <3> to <7>, wherein the other layer is a layer containing a (meth)acrylic resin.
<9> The polycarbonate resin film according to <1> or <2> or the multilayer film according to any one of <3> to <8> has a hard coat layer on one side or both sides thereof. , multilayer film.
<10> The polycarbonate resin film according to <1> or <2>, or the multilayer film according to any one of <3> to <9> has a masking film on one side or both sides, multilayer film.
<11> A display device comprising the polycarbonate resin film according to <1> or <2> and/or the multilayer film according to any one of <3> to <10>.
<12> The method for producing a polycarbonate resin film according to <1> or <2>, wherein the roll contact between the first cooling roll and the second cooling roll in the direction perpendicular to the rotation axis direction of the rolls A method for producing a polycarbonate resin film, wherein the point-to-point distance is 160 to 450 mm.
<13> The method for producing a polycarbonate resin film according to <12>, wherein the peripheral speed ratio between the first cooling roll and the take-up roll is 1:0.995 to 1:0.975.
<14> The method for producing a polycarbonate resin film according to <12> or <13>, comprising extruding the resin composition for forming a polycarbonate resin film through a T-die, wherein the T-die has a width of 600 mm or more.
<15> The length of contact between the second cooling roll and the semi-molten polycarbonate resin film in the direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm, <12> to <14> A method for producing a polycarbonate resin film according to any one of.
<16> The method for producing a multilayer film according to any one of <3> to <8>, wherein the first cooling roll and the second cooling roll are perpendicular to the rotation axis direction of the rolls. A method for producing a multilayer film, wherein the inter-roll point-to-point distance in the direction is 160-450 mm.
<17> The method for producing a multilayer film according to <16>, wherein the peripheral speed ratio between the first cooling roll and the take-up roll is 1:0.995 to 1:0.975.
<18><16> or <17>, including extruding a resin composition for forming a polycarbonate resin film and a resin composition for forming another layer from a T-die, wherein the T-die has a width of 600 mm or more. A method for producing a multilayer film according to 1.
<19><16> to <18>, wherein the contact length between the second cooling roll and the semi-molten multilayer film in the direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm. A method for producing a multilayer film according to any one of the above.
<20> The method for producing a multilayer film according to any one of <16> to <19>, wherein the other layer is a layer containing a (meth)acrylic resin.

INDUSTRIAL APPLICABILITY According to the present invention, a polycarbonate resin film using PC-A as a raw material, which has a low retardation property and uniform main axis orientation, as well as a multilayer film, a display device, and a polycarbonate resin film are manufactured. Methods and methods of making multilayer films are now available.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows an example of the multilayer film of this embodiment. It is a schematic diagram which shows the method of manufacturing the polycarbonate resin film of this embodiment using a roll. FIG. 3 is a partially enlarged view of FIG. 2; FIG. 2 is a schematic diagram mainly for explaining the distance between roll-to-roll points of a semi-molten polycarbonate resin film. FIG. 3 is a partially enlarged view of FIG. 2; FIG. 4 is a schematic diagram mainly for explaining the contact length between the second cooling roll and the semi-molten polycarbonate resin film in the direction perpendicular to the rotation axis direction of the rolls.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "this embodiment") for implementing this invention is demonstrated in detail. In addition, the following embodiment is an example for explaining the present invention, and the present invention is not limited only to this embodiment.
In this specification, the term "~" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.
In this specification, various physical property values and characteristic values are at 23° C. unless otherwise specified.
In the description of a group (atomic group) in the present specification, a description that does not describe substitution or unsubstituted includes a group (atomic group) having no substituent as well as a group (atomic group) having a substituent. For example, an "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, the notations that do not describe substituted and unsubstituted are preferably unsubstituted.
As used herein, "(meth)acryl" represents both or either acryl and methacryl.
In the present specification, weight average molecular weight and number average molecular weight are polystyrene equivalent values measured by GPC (gel permeation chromatography) unless otherwise specified.
As used herein, the term "film" refers to a generally flat formed body having a thin thickness relative to its length and width, respectively, and is intended to include a "sheet." In addition, the "film" in this specification may be a single layer or multiple layers, but a single layer is preferred.
If the standards shown in this specification differ from year to year in terms of measurement methods, etc., the standards as of January 1, 2021 shall be used unless otherwise specified.

<Polycarbonate resin film>
The polycarbonate resin film of the present embodiment is a polycarbonate resin film containing a polycarbonate resin and satisfying conditions 1 to 3 below.
Condition 1: Polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1).
Condition 2: The deviation from the average value of the principal axis azimuth angle of the film is within ±11°.
Condition 3: The film has a retardation of 5 to 50 nm.
formula (1)

In this embodiment, by adjusting the manufacturing method, it is possible to provide a polycarbonate resin film having low retardation and uniform principal axis orientation while using a polycarbonate resin made from PC-A as a raw material. Furthermore, by providing another layer, for example, a high-hardness resin layer such as a (meth)acrylic resin layer on the surface (preferably the surface) of the polycarbonate resin film of the present embodiment, a high-hardness film (multilayer film) can be obtained.

The main structural unit of the polycarbonate resin used in the polycarbonate resin film of the present embodiment is a structural unit represented by the following formula (1).
formula (1)

Here, the “structural unit whose main structural unit is represented by formula (1)” is usually a structural unit represented by formula (1) in 85% by mass or more of the polycarbonate resin contained in the polycarbonate resin film. That is, 90% by mass or more is preferably a structural unit represented by formula (1), more preferably 95% by mass or more is a structural unit represented by formula (1), and the terminal structure is It is more preferable that 99% by mass or more of the excluding the structural unit is the structural unit represented by the formula (1). A representative example of such a polycarbonate resin is PC-A.

The polycarbonate resin used in the present embodiment may be a polycarbonate resin obtained by adding a monohydric phenol represented by the following formula (2) as a terminal terminator for the purpose of controlling the glass transition temperature. good. Specifically, a polycarbonate resin containing a structural unit represented by the above formula (1) and produced using a monohydric phenol represented by the formula (2) as a terminal terminator is exemplified.

(In formula (2), R ₁ represents an alkyl group having 8 to 36 carbon atoms or an alkenyl group having 8 to 36 carbon atoms; R ₂ to R ₅ each independently represent a hydrogen atom, a halogen atom, a substituted represents an alkyl group having 1 to 20 carbon atoms which may have a group, or an aryl group having 6 to 12 carbon atoms which may have a substituent, wherein the substituent is a halogen atom, 1 to 20 alkyl group, or an aryl group with 6 to 12 carbon atoms.)
The monohydric phenol represented by Formula (2) is preferably a monohydric phenol represented by Formula (3).

(In formula (3), R ₁ represents an alkyl group having 8 to 36 carbon atoms or an alkenyl group having 8 to 36 carbon atoms.)

The number of carbon atoms in R ₁ in formula (2) or formula (3) is more preferably within a specific numerical range. Specifically, the upper limit of the carbon number of R ₁ is preferably 30 or less, more preferably 22 or less, and particularly preferably 18 or less. Also, the lower limit of the number of carbon atoms in R ₁ is preferably 10 or more, more preferably 12 or more. When the carbon number of R ₁ in formula (2) or formula (3) is within the above range, the productivity (economic efficiency) is excellent, the rise in the glass transition temperature of the polycarbonate resin is suppressed, and the thermoformability is excellent. Among the monohydric phenols represented by formula (2) or formula (3), either or both of parahydroxybenzoic acid hexadecyl ester and parahydroxybenzoic acid 2-hexyldecyl ester can be used as a terminal terminator. Especially preferred.
For example, when a monohydric phenol in which R ₁ is an alkyl group having 16 carbon atoms in the formula (3) is used as a terminal terminator, a polycarbonate excellent in glass transition temperature, melt fluidity, moldability, drawdown resistance, etc. It is particularly preferred because a resin can be obtained.
Polycarbonate resins using such a monohydric phenol as a terminal terminator include, for example, Iupizeta T-1380 (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

The weight average molecular weight (Mw) of the polycarbonate resin used in this embodiment is preferably 15,000 or more, more preferably 20,000 or more, from the viewpoint of impact resistance and thermal stability. Also, the weight average molecular weight (Mw) of the polycarbonate resin is preferably 75,000 or less, more preferably 65,000 or less.
Specific examples of the polycarbonate resin that can be used in the present embodiment preferably include Iupilon S-2000, Iupilon S-1000, and Iupilon E-2000 manufactured by Mitsubishi Engineering-Plastics.

The content of the polycarbonate resin in the polycarbonate resin film of the present embodiment is usually 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. It is more preferably 95% by mass or more, and even more preferably 98% by mass or more. The upper limit of the content of the polycarbonate resin in the polycarbonate resin film may be 100% by mass.
The polycarbonate resin film of the present embodiment may contain only one type of polycarbonate resin, or may contain two or more types. When two or more types are included, the total amount is preferably within the above range.

The polycarbonate resin film of the present embodiment may be formed from polycarbonate resin alone, or may be formed from a resin composition containing polycarbonate resin and additives. As the additives, those commonly used in resin sheets can be used, specifically, antioxidants, anti-coloring agents, anti-static agents, release agents, lubricants, dyes, pigments, plasticizers. , flame retardants, resin modifiers, compatibilizers, and reinforcing agents such as organic and inorganic fillers. Only one of these additives may be used, or two or more thereof may be used. The method of mixing the additive and the polycarbonate resin is not particularly limited, and a method of compounding the entire amount, a method of dry blending a masterbatch, a method of dry blending the entire amount, and the like can be used. The amount of the additive is preferably 0 to 10% by mass, more preferably 0 to 7% by mass, based on the total mass of the polycarbonate resin film (that is, the resin composition for forming the polycarbonate resin composition). It is preferably 0 to 5% by mass, and particularly preferably 0 to 5% by mass.

The polycarbonate resin film of the present embodiment satisfies Condition 1 above. That is, in the polycarbonate resin film of the present embodiment, the deviation from the average value of the main axis azimuth angles is within ±11°. Although the polycarbonate resin film of the present embodiment has some retardation, it is preferable in that the main axis azimuth angle can be made close to 90°.
The deviation from the average value of the principal axis azimuth angles is more preferably ±10° or less, still more preferably ±9° or less, even more preferably ±8° or less, and ±6° or less. is even more preferable, ±4° or less is particularly preferable, and ±3° or less is even more preferable. Ideally, the lower limit of the deviation from the average value of the main axis azimuth angle is 0°, but even if it is ±0.1° or more, the required performance is satisfied, and ±1° or more is practical. In this embodiment, the deviation from the average value of the principal axis azimuth angle is achieved by producing a polycarbonate resin film by a predetermined method described later.

The average principal axis azimuth angle in the polycarbonate resin film of the present embodiment is preferably 88° or more, more preferably 89° or more, further preferably 90° or more, and 95° or less. preferably 93° or less, and even more preferably 92° or less.
From the viewpoint of stabilizing the main axis azimuth and phase difference, the thickness deviation of the polycarbonate resin film of the present embodiment is preferably within the average value ± 15%, more preferably within the average value ± 10%, and further within the average value ± 5%. preferable. By setting such a range, when the molten resin flowing out of the T-die is crimped between the touch roll and the first cooling roll, and the mirror surface of the touch roll and the first cooling roll is transferred, the mirror surface due to the thickness deviation It is possible to effectively suppress the fact that the transfer is not performed and the appearance becomes poor).

The polycarbonate resin film of this embodiment has a low retardation (maximum retardation). Specifically, the retardation of the film is 50 nm or less, preferably 48 nm or less, more preferably 40 nm or less, and even more preferably 38 nm or less. Moreover, the lower limit of the retardation of the film is 5 nm or more. A polycarbonate resin film, particularly PC-A, tends to exhibit a retardation as compared with an acrylic resin film or the like. can be effectively suppressed.

The thickness of the polycarbonate resin film of the present embodiment can be appropriately determined according to its use, etc., but is preferably 50 μm or more, preferably 70 μm or more, more preferably 100 μm or more, and more preferably 150 μm. or more, or 200 μm or more. When the thickness is equal to or higher than the above lower limit, the rigidity of the film is increased, and when the film is used as a resin cover, the deflection of the film is reduced, which tends to make it easier to use as a large-sized resin cover. The upper limit of the thickness of the polycarbonate resin film is preferably 1500 μm or less, more preferably 1000 μm or less, even more preferably 500 μm or less, even more preferably 490 μm or less, and 450 μm or less. is more preferably 400 μm or less. By making it equal to or less than the above upper limit value, it becomes easy to reduce the deviation of the main axis azimuth angle, and when it is used as a resin cover for a head-up display, there is a tendency that image distortion is reduced.

The width of the polycarbonate resin film of the present embodiment is preferably 800 mm or more, more preferably 1000 mm or more, and even more preferably 1200 mm or more. By making it more than the said lower limit, when constructing a hard coat etc. in a post process, it becomes possible to construct efficiently. In addition, the upper limit of the width of the polycarbonate resin film of the present embodiment is preferably 5000 mm or less, more preferably 3000 mm or less, further preferably 2500 mm or less, and even more preferably 2200 mm or less. 2000 mm or less is even more preferable.

<Multilayer film>
The polycarbonate resin film of the present embodiment may be used as a single-layer or multilayer film consisting only of the polycarbonate resin film, but may be a multilayer film with other layers other than the polycarbonate resin film of the present embodiment. That is, the multilayer film of this embodiment is a multilayer film having a polycarbonate resin film and at least one other layer.
Another embodiment of the multilayer film of the present embodiment is a multilayer film having a polycarbonate resin film and at least one other layer and satisfying conditions A to C below.
Condition A: Polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1);
Condition B: the deviation from the average value of the main axis azimuth angle of the film is within ±11°;
Condition C: The film has a retardation of 5 to 50 nm.
formula (1)

The main structural unit of the polycarbonate resin used in the multilayer film of the present embodiment is a structural unit represented by the following formula (1). These details are synonymous with Condition 1 described in the polycarbonate resin film of the present embodiment, and the preferred range is also synonymous.
The preferred range of the polycarbonate resin film is also synonymous with the preferred range of the polycarbonate resin film of the present embodiment.

FIG. 1 shows an example of the multilayer film of this embodiment, where 1 indicates a polycarbonate resin film and 2 indicates other layers.
In the multilayer film of the present embodiment, the polycarbonate resin film may consist of only one layer or two or more layers, usually one or two layers.

The multilayer film of this embodiment satisfies condition B. That is, in the multilayer film of the present embodiment, the deviation from the average value of the principal axis azimuth angles is within ±11°.
The deviation from the average value of the principal axis azimuth angles is preferably ±10° or less, more preferably ±9° or less, even more preferably ±8° or less, and ±7° or less. ±6° or less is particularly preferable, and ±5° or less is even more preferable. Ideally, the lower limit of the deviation from the average value of the main axis azimuth angle is 0°, but even if it is ±0.1° or more, the required performance is satisfied, and ±1° or more is practical.
The azimuth angle of the main axis of the multilayer film preferably satisfies the above range when measured from the other layer side, not from the polycarbonate resin film side.

The multilayer film of this embodiment satisfies condition C. That is, the multilayer film of the present embodiment preferably has a low retardation (maximum retardation). Specifically, the retardation of the film is 50 nm or less, preferably 45 nm or less, more preferably 40 nm or less, even more preferably 35 nm or less, and more preferably 30 nm or less. More preferably, it is still more preferably 25 nm or less. Moreover, the lower limit of the retardation of the multilayer film is 5 nm or more.
As for the retardation of the multilayer film, the value measured from the other layer side preferably satisfies the above range.

The average principal axis azimuth angle in the multilayer film of the present embodiment is preferably 88° or more, more preferably 89° or more, further preferably 90° or more, and 93° or less. , more preferably 92° or less, and even more preferably 91° or less. The average principal axis azimuth angle in the multilayer film refers to the average principal axis azimuth angle in the original film, and when incorporated into an actual display, etc., the average principal axis azimuth angle may deviate depending on the cut direction. be.
From the viewpoint of stabilizing the principal axis azimuth angle and retardation, the thickness deviation of the multilayer film of the present embodiment is preferably within ±15% of the average value, more preferably within ±10% of the average value, and further preferably within ±5% of the average value. . By setting such a range, when the molten resin flowing out of the T-die is crimped between the touch roll and the first cooling roll, and the mirror surface of the touch roll and the first cooling roll is transferred, the mirror surface due to the thickness deviation It is possible to effectively prevent the transfer from being performed, resulting in poor appearance.

In the multilayer film of the present embodiment, the total thickness of the polycarbonate resin film and the other layer (preferably (meth)acrylic resin layer) is preferably 50 to 1500 μm. The lower limit of the total thickness is preferably 100 μm or more, more preferably 125 μm or more, still more preferably 130 μm or more, even more preferably 140 μm or more, and may be 180 μm or more. . The upper limit of the total thickness is preferably 800 µm or less, more preferably 600 µm or less, even more preferably 550 µm or less, even more preferably 500 µm or less, and even more preferably 450 µm or less. It may be 400 μm or less.
In the multilayer film of the present embodiment, the total thickness (total thickness) of the multilayer film is preferably 100-3000 μm.

The width of the multilayer film of the present embodiment is preferably 800 mm or more, more preferably 1000 mm or more, and even more preferably 1200 mm or more. The upper limit of the width of the multilayer film of the present embodiment is preferably 5000 mm or less, more preferably 3000 mm or less, even more preferably 2500 mm or less, and even more preferably 2200 mm or less. The following are even more preferable.

The multilayer film of the present embodiment preferably has a pencil hardness of HB or higher, more preferably H or higher, measured from the other layer side (eg, layer 2 in FIG. 1). Although the upper limit of the pencil hardness is not particularly defined, 3H or less is practical. The pencil hardness is measured by the method described in Examples below (the same applies to the pencil hardness below). Moreover, in the multilayer film of the present embodiment, it is preferable that the side having a higher pencil hardness satisfies the above pencil hardness.

From the viewpoint of transparency, the haze of the multilayer film of the present embodiment is preferably 2% or less, more preferably 1% or less, and even more preferably 0.5% or less. Haze (unit: %) can be measured using a haze meter under the condition of D65 light source 10° field of view.

The other layers included in the multilayer film of the present embodiment are not particularly limited in terms of their types, but are exemplified by a layer containing a high-hardness resin, a masking film, and a hard coat layer. Furthermore, the number of other layers may be 1 layer or 2 or more layers, usually 1 to 7 layers, preferably 1 to 5 layers, more preferably 1 to 3 layers.
In this specification, a layer containing a high-hardness resin may be referred to as a high-hardness resin layer.

The other layer is preferably a film having low retardation and uniform principal axis orientation. In particular, when the other layer is a (meth)acrylic resin layer and/or a hard coat layer, these layers are also preferably films having a low retardation property and uniform principal axis orientation.
Specifically, the other layer (preferably the (meth)acrylic resin layer and/or the hard coat layer, more preferably the (meth)acrylic resin layer) has a deviation of ± It is preferable that the angle is within 11° and the retardation of the film is 5 to 50 nm. By combining such a film with a polycarbonate resin film to form a multi-layer body, a multi-layer film having low retardation and uniform main axis orientation can be obtained.
The retardation of the other layer is preferably 45 nm or less, more preferably 40 nm or less, even more preferably 35 nm or less, even more preferably 30 nm or less, and 25 nm or less. Even more preferable. Also, the lower limit of the retardation of the other layer is 5 nm or more.
Further, the deviation from the average value of the main axis azimuth angles in the other layers is preferably ±11° or less, preferably ±10° or less, more preferably ±9° or less, and ± It is more preferably 8° or less, even more preferably ±7° or less, particularly more preferably ±6° or less, and even more preferably ±5° or less. Ideally, the lower limit of the deviation from the average value of the main axis azimuth angle is 0°, but even if it is ±0.1° or more, the required performance is satisfied, and ±1° or more is practical.
On the other hand, when the other layer is a film that can be peeled off during use, such as when the other layer is a masking film, the other layer is not necessarily a film having a low retardation property and a uniform principal axis orientation.

The thickness of each of the other layers is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 20 μm or more, even more preferably 25 μm or more, and 30 μm or more. It is even more preferable to have By making it more than the said lower limit, there exists a tendency for pencil hardness to become high. The thickness of the other layer is preferably 100 μm or less, more preferably 85 μm or less, even more preferably 70 μm or less, even more preferably 50 μm or less, and 40 μm or less. is even more preferred. When the content is equal to or less than the above upper limit, the toughness of the film is increased, and problems such as cracking due to handling tend to be less likely to occur. In particular, when the other layer is a (meth)acrylic resin layer, the thickness of the other layer is preferably 20 to 100 μm.

In the multilayer film of the present embodiment, the ratio of the polycarbonate resin film to the thickness of one other layer (preferably (meth)acrylic resin layer) is preferably 2/1 to 10/1. It is more preferably 1 to 8/1, and may be 2/1 to 7/1.

<<First example of multilayer film>>
A first example of the multilayer film of the present embodiment is a multilayer film having a polycarbonate resin film and at least one other layer, wherein the at least one other layer is a resin layer containing a high hardness resin ( A high-hardness resin layer), preferably a multilayer film that is a resin layer containing a high-hardness resin as a main component. Here, the main component means that 50% by mass or more of the constituent components of the other layer is a high hardness resin, preferably 70% by mass or more is a high hardness resin, and 80% by mass or more is a high hardness resin. It is more preferably a resin, more preferably 90% by mass or more of a high hardness resin, and even more preferably 99% by mass or more of a high hardness resin.

A (meth)acrylic resin is exemplified as the high-hardness resin. That is, the other layer is preferably a layer containing (meth)acrylic resin ((meth)acrylic resin layer).
In the present embodiment, the high-hardness resin is preferably a resin having a pencil hardness of HB or higher, and more preferably a resin having a pencil hardness of H or higher. The high hardness resin contained in the high hardness resin layer may be one kind or two or more kinds. Although the upper limit of the pencil hardness of the high-hardness resin is not particularly defined, for example, 3H or less is practical.

As described above, the high-hardness resin includes (meth)acrylic resin, but is not limited thereto, and a wide range of known high-hardness resins can be used. Hard resins are typically thermoplastic resins.
As the (meth)acrylic resin, a polymer of (meth)acrylic compound monomers can be used. Examples of (meth)acrylic compound monomers include acrylonitrile, methacrylonitrile acrylic acid, methacrylic acid and (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate and 2-ethylhexyl methacrylate. is mentioned. Among them, methyl methacrylate (MMA) is preferred. Two or more of these (meth)acrylic compound monomers may be mixed. Also, other monomers such as vinyl compounds (eg, styrene) may be copolymerized within the scope of the present invention. In the (meth)acrylic resin used in the present embodiment, the proportion of (meth)acrylic compound monomer units is preferably 80% by mass or more, more preferably 90% by mass or more.

The high-hardness resin layer may be formed only from a high-hardness resin (preferably (meth)acrylic resin), or formed from a resin composition containing a high-hardness resin (preferably (meth)acrylic resin) and an additive. may have been As the additives, those commonly used in resin sheets can be used, and examples of such additives include antioxidants, anti-colorants, antistatic agents, release agents, lubricants, dyes, , pigments, plasticizers, flame retardants, resin modifiers, compatibilizers, reinforcing agents such as organic fillers and inorganic fillers. The method of mixing the additive and the resin is not particularly limited, and a method of compounding the total amount, a method of dry-blending a masterbatch, a method of dry-blending the total amount, or the like can be used. The amount of the additive is preferably 0 to 10% by mass, more preferably 0 to 7% by mass, based on the total mass of the high-hardness resin layer (that is, the resin composition for forming another layer). More preferably, 0 to 5% by mass is particularly preferable.

The thickness of the high-hardness resin layer (preferably (meth)acrylic resin layer) is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more. By making it more than the said lower limit, there exists a tendency for pencil hardness to become high. The thickness of the high-hardness resin layer is preferably 100 μm or less, more preferably 85 μm or less, still more preferably 70 μm or less, even more preferably 50 μm or less, and 40 μm or less. is even more preferable. When the content is equal to or less than the above upper limit, the toughness of the film is increased, and problems such as cracking due to handling tend to be less likely to occur.

In the multilayer film of the first example, the thickness ratio between the polycarbonate resin film and the high-hardness resin layer (preferably (meth)acrylic resin layer) is preferably 2/1 to 10/1. It is more preferably 1 to 8/1, and may be 2/1 to 7/1.

The multilayer film of the first example has at least one polycarbonate resin film and one or more high-hardness resin layers (preferably (meth)acrylic resin layers) each (preferably one layer each), As a preferred embodiment, the total thickness of the polycarbonate resin film and the high-hardness resin layer is 50 to 1500 μm. The lower limit of the total thickness is preferably 100 μm or more, more preferably 130 μm or more, even more preferably 140 μm or more, and may be 180 μm or more. The upper limit of the total thickness is preferably 1000 μm or less, more preferably 800 μm or less, even more preferably 550 μm or less, even more preferably 500 μm or less, and 450 μm or less. It may be 400 μm or less.

The multilayer film of the first example preferably has a pencil hardness of HB or higher, more preferably H or higher, measured from the high-hardness resin layer side. Although the upper limit of the pencil hardness is not particularly defined, 3H or less is practical.

<<Second example of multilayer film>>
A second example of the multilayer film of the present embodiment is the polycarbonate resin film of the present embodiment, or the multilayer film of the present embodiment (in particular, the multilayer film of the first example above and the multilayer film of the third example described later). ) with a masking film on one or both sides.
The masking film may be provided on the surface of the polycarbonate resin film, may be provided on the surface of the high-hardness resin layer, may be provided on the surface of the hard coat layer, or may be provided on the surface of any other layer. good too.

The masking film preferably has an adhesive surface that has an appropriate amount of adhesive strength with adjacent layers. The masking film may be a single layer consisting of only an adhesive layer, but preferably has a two-layer structure consisting of a substrate and an adhesive layer. Moreover, the masking film may have a multilayer structure further including layers other than the base material and the adhesive layer described above.

The base material of the masking film is preferably a thermoplastic resin film, more preferably a polyolefin resin film. As the polyolefin resin, for example, polyethylene, polypropylene, or the like can be used, and it may be a homopolymer or a copolymer. Among polyolefin resins, polyethylene is preferred. As polyethylene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and the like can be used. Low density polyethylene is preferred.
As the polyolefin copolymer, a copolymer of ethylene and/or propylene and a monomer copolymerizable therewith can be used. Examples of monomers that can be copolymerized with ethylene and/or propylene include α-olefins, styrenes, dienes, cyclic compounds, oxygen atom-containing compounds, and the like.
The polyolefin resin may contain a modified polyolefin resin modified with a small amount of carboxyl group-containing monomers such as acrylic acid, maleic acid, methacrylic acid, maleic anhydride, fumaric acid and itaconic acid. Modification is usually possible by copolymerization or graft modification.

The polyolefin resin film that is the substrate of the masking film preferably contains 80% by mass or more of the polyolefin resin, more preferably 90% by mass or more of the polyolefin resin, based on the total mass of the substrate, and more preferably 95% by mass. % or more polyolefin resin.

The adhesive layer of the masking film is preferably molded from thermoplastic resin containing elastomer. Examples of thermoplastic resins contained in the adhesive layer include polyolefin resins such as polypropylene and modified polyolefin. As the polyolefin resin contained in the masking film, for example, polyethylene, polypropylene, or the like can be used, and it may be a homopolymer or a copolymer. Among polyolefin resins, polyethylene is preferred.

The adhesive layer of the masking film preferably contains 80% by mass or more of thermoplastic resin, more preferably 90% by mass or more of thermoplastic resin, based on the total mass of the adhesive layer, and more preferably 95% by mass or more. More preferably, it contains a thermoplastic resin.

The value of adhesive force on the adhesive surface of the masking film is preferably 5 (mN/25 mm) or more and 5000 (mN/25 mm) or less, more preferably, against the surface of PMMA (polymethyl methacrylate resin layer). It is 9 (mN/25mm) or more and 3000 (mN/25mm) or less.

The thickness of the masking film is preferably 10 µm or more, more preferably 15 µm or more, and even more preferably 20 µm or more. The thickness of the masking film is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less.

In addition to the above, details of the masking film can be referred to JP 2021-123079, paragraphs 0013 to 0025 of WO 2020/031968, and paragraphs 0089 to 0094 of JP 2017-185772. , the contents of which are incorporated herein.

<<Third Example of Multilayer Film>>
A third example of the multilayer film of the present embodiment is either the polycarbonate resin film of the present embodiment or the multilayer film of the present embodiment (in particular, the multilayer film of the first example and the multilayer film of the second example). It is a multilayer film having a hard coat layer on one or both sides of the film.
The hard coat layer may be provided on the surface of the polycarbonate resin film, may be provided on the surface of the high-hardness resin layer, or may be provided on the surface of any other layer.

As the hard coat layer, (meth)acrylic, silicon, melamine, urethane, epoxy, and other known compounds that form a crosslinked film can be used. ) acrylic and (meth)urethane acrylate are preferred. As for the curing method, known methods such as ultraviolet curing, heat curing, and electron beam curing can be used. Among these, the surface to be the front side preferably has a pencil hardness of HB or more, more preferably H or more. A practical expression of the pencil hardness is 3H or less.
A method for applying the hard coat liquid is not particularly limited, and a known method can be used. Examples thereof include a spin coating method, a dipping method, a spray method, a slide coating method, a bar coating method, a roll coating method, a gravure coating method, a meniscus coating method, a flexographic printing method, a screen printing method, a beat coating method, and a picking method.
The hardcoat layer may be further modified. For example, one or more of antireflection treatment, antifouling treatment, antistatic treatment, weather resistance treatment, infrared cut treatment, and antiglare treatment can be applied. These treatment methods are not particularly limited, and known methods can be used. For example, a method of applying a reflection-reducing paint, a method of vapor-depositing a dielectric thin film, a method of applying an antistatic paint, etc. can be mentioned. is more preferably 40 μm or less, and more preferably 10 μm or less. Sufficient hardness can be obtained by setting the thickness to 1 μm or more. Moreover, when the film thickness is 40 μm or less, the occurrence of cracks during bending can be suppressed.

As the hard coat layer, in addition to the above, paragraphs 0045 to 0055 of JP 2013-020130, paragraphs 0073 to 0076 of JP 2018-103518, paragraph 0062 of JP 2017-213771 0082 can be referred to, and the contents thereof are incorporated herein.

Examples of the layer structure of the multilayer film of this embodiment include the following. Needless to say, the multilayer film of the present embodiment is not limited to these.
(1) (meth) acrylic resin layer / polycarbonate resin layer (2) masking film / (meth) acrylic resin layer / polycarbonate resin layer / masking film (3) hard coat layer / (meth) acrylic resin layer / polycarbonate resin layer ( 4) Masking film/hard coat layer/(meth)acrylic resin layer/polycarbonate resin layer/masking film (5) Hard coat layer/(meth)acrylic resin layer/polycarbonate resin layer/hard coat layer (6) Masking film/hard Coat layer/(meth)acrylic resin layer/polycarbonate resin layer/hard coat layer/masking film (7) (meth)acrylic resin layer/polycarbonate resin layer/hard coat layer (8) Masking film/(meth)acrylic resin layer/ Polycarbonate resin layer/hard coat layer/masking film (9) (meth)acrylic resin layer/polycarbonate resin layer/(meth)acrylic resin layer (10) Masking film/(meth)acrylic resin layer/polycarbonate resin layer/(meth) Acrylic resin layer/masking film (11) Hard coat layer/(meth)acrylic resin layer/polycarbonate resin layer/(meth)acrylic resin layer (12) Masking film/hard coat layer/(meth)acrylic resin layer/polycarbonate resin layer / (Meth) acrylic resin layer / masking film (13) hard coat layer / (meth) acrylic resin layer / polycarbonate resin layer / (meth) acrylic resin layer / hard coat layer (14) masking film / hard coat layer / (meta ) acrylic resin layer / polycarbonate resin layer / (meth)acrylic resin layer / hard coat layer / masking film

<Application>
The use of the polycarbonate resin film and/or multilayer film of the present embodiment is not particularly specified, and it can be used for various applications such as electronic and electrical equipment, and is preferably used for display devices, such as liquid crystal display devices and organic EL. It is more preferable to use it for a display device or a head-up display device.

<Method for producing polycarbonate resin film>
The polycarbonate resin film of the present embodiment is not particularly defined as long as it can be manufactured so as to satisfy the above conditions 1 to 3, and for example, extrusion molding and cast molding are preferable. As an example of extrusion molding, there is a method in which the resulting semi-molten polycarbonate resin film is passed through rolls and cooled and solidified to form a product. More specifically, a resin composition for forming a polycarbonate resin film consisting of only a polycarbonate resin, or a resin composition for forming a polycarbonate resin film containing a polycarbonate resin and an additive is extruded from a T-die or the like to obtain a semi-melt. A polycarbonate resin film having a shape is cooled and solidified while being passed through a roll to form a product. Here, the resin composition for forming a polycarbonate resin film is extruded from a T-die or the like after melting and kneading pellets, flakes or powder in an extruder. The extruder may be single-screw or twin-screw, and may be vented or non-vented.
When the resin composition for forming a polycarbonate resin film is extruded from the T-die, the temperature of the resin substrate is preferably 200° C. or higher, more preferably 240° C. or higher, further preferably 260° C. or lower, and preferably 320° C. or lower. , 300° C. or lower, and more preferably 280° C. or lower.

For the polycarbonate resin film of the present embodiment, it is preferable to precisely set the distance between the first cooling roll and the second cooling roll while conveying the semi-molten polycarbonate resin film.
Specifically, in the method for producing a polycarbonate resin film of the present embodiment, the inter-roll point distance between the first cooling roll and the second cooling roll in the direction perpendicular to the rotation axis direction of the rolls is 160. including being ~450 mm. The direction perpendicular to the rotation axis direction is usually the direction in which the roll rotates and the film is conveyed.
FIG. 2 shows a schematic diagram of the production of the polycarbonate resin film of the present embodiment using rolls, where 21 is a T die, 22 is a touch roll, and 23 is a first cooling roll. , 24 indicates a polycarbonate resin film (semi-melted polycarbonate resin film) in the process of production, 25 indicates a second cooling roll, and 26 indicates a third roll (take-up roll). Here, the polycarbonate resin film 24 during the manufacturing process is meant to include, for example, a molten polycarbonate resin film before being completely cooled after being extruded from a T-die.
In FIG. 2, a resin composition for forming a semi-molten polycarbonate resin film is extruded from a T-die 21 into a film, passes through a touch roll 22 and a first cooling roll 23, and then passes through a second cooling roll 25. pass through. In this embodiment, the inter-roll point distance between the first cooling roll 23 and the second cooling roll 25 in the direction perpendicular to the rotation axis direction of the rolls is set to 160 to 450 mm. With such a structure, the time for applying tension to the film 24 can be precisely adjusted, the tension can be uniformly applied to the film 24 by the second cooling roll 25, and the principal axis of the film can be easily straightened. be able to.
Here, the inter-roll contact distance between the first cooling roll and the second cooling roll in the direction perpendicular to the rotation axis direction of the rolls will be described with reference to FIG. FIG. 3 is a partial enlarged view of FIG. 2, and the reference numerals are the same as in FIG. First, the rotation axis direction of the roll is the direction perpendicular to the direction in which the roll rotates, that is, the direction perpendicular to the direction in which the film (usually a semi-molten polycarbonate resin film) is conveyed. Therefore, in relation to the first cooling roll 23, the direction perpendicular to the rotation axis direction of the rolls means the center (23a) of the rotation axis of the first cooling roll 23 and the first cooling roll 23 and the direction of the line connected by the point (23b) where the film 24 is in contact. A point ( 23 b ) where the first cooling roll 23 and the film 24 are in contact is a point of contact with the first cooling roll 23 . Similarly, in terms of the relationship with the second cooling roll 25, the direction perpendicular to the rotation axis direction of the rolls is the center (25a) of the rotation axis of the second cooling roll 25 and the second cooling roll. It refers to the direction of the line connected by the point (25b) where 25 and film 24 are in contact. A point ( 25 b ) where the second cooling roll 25 and the film 24 are in contact is a point of contact with the second cooling roll 25 . In this embodiment, the distance between the contact point 23b between the first cooling roll 23 and the film 24 and the contact point 25b between the second cooling roll 25 and the film 24 (distance between roll contact points) is 160 to 450 mm. becomes.
Note that the contact point 23b between the first cooling roll 23 and the film 24 may not be fixed at one point in a geometrical sense like a contact point. In this case, the point at which the film 24 is finally peeled off from the first cooling roll 23 is defined as a contact point 23b between the first roll 23 and the film 24 . Similarly, the point where the film 24 and the second cooling roll 25 first come into contact with each other is defined as a point of contact 25b between the film 24 and the second cooling roll 25 .
The lower limit of the distance between the points between the rolls is preferably 200 mm or more, more preferably 225 mm or more, still more preferably 250 mm or more, even more preferably 280 mm or more, and 300 mm or more. is even more preferable. By making it equal to or greater than the lower limit, there is a tendency for the uniformity of the main axis azimuth angle to be enhanced. In addition, the upper limit of the distance between the points between the rolls is preferably 420 mm or less, more preferably 400 mm or less, even more preferably 350 mm or less, even more preferably 330 mm or less, and 315 mm or less. It is even more preferable to have By making it equal to or less than the above upper limit, there is a tendency that the uniformity of the main axis azimuth angle becomes high.

The diameter of the first cooling roll is preferably 100 mm or more, more preferably 150 mm or more, still more preferably 200 mm or more, still more preferably 250 mm or more, and 280 mm or more. is even more preferred. By making it equal to or higher than the lower limit, the time that the film contacts the roll at a constant molding speed becomes longer, so that the film temperature over the entire width of the film when the resin is peeled from the roll tends to be constant. The main axis azimuth tends to be uniform. The diameter of the first cooling roll is preferably 1000 mm or less, more preferably 900 mm or less, still more preferably 800 mm or less, even more preferably 700 mm or less, and 650 mm or less. It is even more preferable to have By making it equal to or less than the upper limit, when the semi-molten resin is crimped by the touch roll 22 and the first cooling roll 23, it is possible to bring the T-die lip portion closer to the crimping point, resulting in poor film transfer, die lines, etc. It tends to be easier to improve the poor appearance of
The diameter of the second cooling roll is preferably 100 mm or more, more preferably 150 mm or more, still more preferably 200 mm or more, even more preferably 250 mm or more, and 280 mm or more. is even more preferred. By making it equal to or greater than the lower limit value, the contact length between the first cooling roll 23 and the film 24 can be easily changed arbitrarily by changing the position of the second cooling roll 25 or the position of the guide roll, and the main axis azimuth angle tend to be easier to equalize. The diameter of the first cooling roll is preferably 1000 mm or less, more preferably 900 mm or less, still more preferably 800 mm or less, even more preferably 700 mm or less, and 650 mm or less. It is even more preferable to have When the thickness is equal to or less than the upper limit, the mass of the roll can be reduced, and the position of the second cooling roll 25 tends to be easily changed.

The surface temperature of the first cooling roll is preferably 80° C. or higher, more preferably 90° C. or higher, and even more preferably 95° C. or higher. When the content is equal to or higher than the above lower limit, it tends to be easy to improve appearance defects such as film transfer defects and die lines. The surface temperature of the first cooling roll is preferably 140°C or lower, more preferably 120°C or lower, even more preferably 110°C or lower, and even more preferably 105°C or lower. . When the thickness is equal to or less than the upper limit, the film 24 tends to be easily peeled off from the first cooling roll 23 .
The surface temperature of the second cooling roll is preferably 110° C. or higher, more preferably 120° C. or higher, and even more preferably 130° C. or higher. When the thickness is equal to or higher than the lower limit, the adhesiveness between the second cooling roll 25 and the film 24 is improved, and the separation between the first cooling roll 23 and the film 24 tends to be stabilized. Also, the surface temperature of the first cooling roll is preferably 160° C. or lower, more preferably 150° C. or lower, and even more preferably 145° C. or lower. By making it equal to or less than the above upper limit, it is possible to effectively prevent the adhesion between the second cooling roll 25 and the film 24 to be too high, resulting in poor appearance due to the close contact between the second cooling roll 25 and the film 24. tend to be suppressed.
The difference in surface temperature between the second chill roll and the first chill roll is preferably 10° C. or higher, more preferably 20° C. or higher, and even more preferably 30° C. or higher. When the thickness is equal to or higher than the above lower limit, warping of the film caused by the first cooling roll is alleviated by the second cooling roll, thereby tending to reduce the warping of the film. The difference in surface temperature between the second chill roll and the first chill roll is preferably 60°C or less, more preferably 50°C or less, and even more preferably 45°C or less. By making the thickness equal to or less than the upper limit, it is possible to effectively prevent the warpage of the second cooling roll from becoming too large.

The surface temperature of the touch roll is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher. When the content is equal to or higher than the above lower limit, it tends to be easy to improve appearance defects such as film transfer defects and die lines. Also, the surface temperature of the touch roll is preferably 140° C. or lower, more preferably 110° C. or lower, and even more preferably 105° C. or lower. When the thickness is equal to or less than the above upper limit, it tends to be possible to effectively prevent the film from sticking to the touch roll and resulting in poor appearance.

On the other hand, the materials of the surfaces of the touch roll 22, the first cooling roll 23, and the second cooling roll 25 are not particularly specified, but are preferably metal, and may be mirror-finished. preferable. By using a roll made of such a material, a polycarbonate resin film whose main axis orientation is less likely to vary can be obtained.

In addition, in the method for producing a polycarbonate resin film, the number of cooling rolls does not need to be two, and may be three or more. In this embodiment, it is preferable that the first and second cooling rolls through which the polycarbonate resin extruded from the T-die passes are the first cooling roll and the second cooling roll, respectively.

In this embodiment, the peripheral speed ratio between the first cooling roll and the take-up roll is preferably 1:0.995 to 1:0.975. By setting the peripheral speed ratio to 0.975 or more, the tension between the second cooling roll 25 and the take-up roll is set to an appropriate value, and the azimuth angle of the main axis tends to be more uniform. Further, by setting the circumferential velocity ratio to 0.995 or less, there is a tendency that the phase difference can be easily adjusted within a range of 5 to 50 nm.
Here, the take-up roll corresponds to, for example, the third roll 26 in FIG. That is, the rolls acting to take up the film. It is more preferable that the peripheral speed ratio between the first cooling roll and the take-up roll is 0.980 or more with respect to the peripheral speed 1 of the first cooling roll. Further, the peripheral speed ratio between the first cooling roll and the take-up roll is more preferably 0.993 or less, more preferably 0.990 or less with respect to the peripheral speed 1 of the first cooling roll, It is more preferably 0.987 or less.

In the polycarbonate resin film manufacturing method of the present embodiment, a resin composition for forming a polycarbonate resin film is usually extruded from a T-die 21 as shown in FIG. The width of the T-die is preferably 600 mm or more. When the content is at least the above lower limit, the resulting polycarbonate resin film tends to be more improved in moldability and handleability. The width of the T-die is preferably 800 mm or more, more preferably 1000 mm or more, and even more preferably 1200 mm or more. The upper limit of the width of the T-die is preferably 5000 mm or less, more preferably 3000 mm or less, even more preferably 2500 mm or less, even more preferably 2200 mm or less, and 2000 mm or less. is even more preferable.

In the method for producing a polycarbonate resin film of the present embodiment, the contact length between the second cooling roll and the semi-molten polycarbonate resin film in the direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm. Preferably. By making it equal to or higher than the lower limit, the uniformity of the principal axis orientation tends to be further improved. In addition, by making it equal to or less than the upper limit, the main axis azimuth angle uniformed between the first cooling roll and the second cooling roll is relaxed on the second cooling roll, and as a result, it is possible to prevent the dispersion of the main axis azimuth from becoming large. It is possible to make it difficult for the main axis orientation to fluctuate.
Here, the contact length in the vertical direction is the arc length of the contact between the second cooling roll and the film. For example, as shown in FIG. 4 (the reference numerals in FIG. 4 are the same as those in FIG. 2), it refers to the length 30 where the polycarbonate resin film 24 in the process of production is in contact with the second chill roll 25 . The length here refers to the length of contact with the second cooling roll 25 in the direction perpendicular to the rotation axis of the second cooling roll 25, that is, the transport direction of the polycarbonate resin film. Since the polycarbonate resin film 24 in contact with the second cooling roll 25 is a film in a molten state, it is in contact with the second cooling roll at a constant distance.
The contact length is more preferably 10 mm or longer, more preferably 15 mm or longer, still more preferably 20 mm or longer, still more preferably 30 mm or longer, and further preferably 35 mm or longer. More preferred. The contact length is also preferably 350 mm or less, further preferably 300 mm or less, even more preferably 200 mm or less, even more preferably 150 mm or less, and 100 mm or less. is still more preferable, and may be 80 mm or less. By making it equal to or less than the above upper limit, there is a tendency that the uniformity of the principal axis orientation is further improved.

<Method for producing multilayer film>
The multilayer film of the present embodiment is not particularly limited as long as it satisfies the above conditions A to C and can be manufactured by a polycarbonate resin film and other layers, and known methods can be employed.

In a first example of the method for producing a multilayer film of the present embodiment, the distance between the roll-to-roll points of the first cooling roll and the second cooling roll in the direction perpendicular to the rotation axis direction of the rolls is 160 to 160. Including being 450mm.
Further, in the method for producing a multilayer film of the present embodiment, the peripheral speed ratio between the first cooling roll and the take-up roll is preferably 1:0.995 to 1:0.975.
Furthermore, in the method for producing a multilayer film of the present embodiment, the resin composition for forming the polycarbonate resin film and the resin composition for forming other layers are extruded from a T-die, and the width of the T-die is 600 mm. It is preferable that it is above. That is, usually, a polycarbonate resin film and other layers are co-extruded and produced using rolls in the same manner as in the above-described method for producing a polycarbonate resin film.
Furthermore, in the method for producing a multilayer film of the present embodiment, the contact length between the second cooling roll and the semi-molten multilayer film in the direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm. is preferably In the method for producing a multilayer film of the present embodiment, the second cooling roll may be in contact with the polycarbonate resin film or may be in contact with other layers.
In the first example of the multilayer film, the other layer is preferably a (meth)acrylic resin layer.
Moreover, after manufacturing a multilayer film by the method described in the first example, a hard coat layer and/or a masking film may be provided thereon.
In addition to the above, the details of the first example of the method for producing a multilayer film of the present embodiment are as described above, except that the multilayer film is produced by laminating at least one other layer in addition to the polycarbonate resin film. is the same as the method for producing a polycarbonate resin film, and the preferred range is also the same. Moreover, the obtained multilayer film is the same as the multilayer film of the present embodiment described above, and the preferred range is also the same.

A second example of the method for producing a multilayer film of the present embodiment is a method of forming another layer after molding a polycarbonate resin film. Specifically, bonding a polycarbonate resin and a high-hardness resin layer together can be mentioned. Further, a hard coat layer and/or a masking film may be provided on the polycarbonate resin film or on the multilayer film of the polycarbonate resin and the high-hardness resin layer.

In addition to the above, the descriptions of JP-A-2018-103518 and JP-A-2016-060786 can be referred to within the scope of the present invention for the production of multilayer films, and the contents of these are incorporated herein. be

EXAMPLES The present invention will be described more specifically with reference to examples below. The materials, usage amounts, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Accordingly, the scope of the present invention is not limited to the specific examples shown below.
If the measuring instruments and the like used in the examples are discontinued and difficult to obtain, other instruments having equivalent performance can be used for measurement.

Various physical property values were measured according to the following methods.

<Pencil hardness>
The pencil hardness of the film was measured with a load of 500 g±10 g, and the measuring method other than the load was based on JIS K5600-5-4.
For the multilayer film, the hardness was measured from the higher hardness side. In the multilayer film shown in this example, the measurement was performed from the high-hardness resin layer ((meth)acrylic resin layer) side.

<Main axis azimuth>
The azimuth angle of the main axis of the polycarbonate resin film and multilayer film was the azimuth angle of the slow axis representing the direction of the maximum refractive index. Also, since the value of the azimuth angle of the main axis changes depending on the measurement point, the average value of the azimuth angle of the main axis is measured in this embodiment.
PA-300 manufactured by Photonic Lattice was used to measure the principal axis azimuth angle. The film was placed so that the direction perpendicular to the longitudinal direction was directed from the front to the back of the device. As the measurement points of the apparatus, the center point connecting the diagonals of the film was used as the center point, and the main axis azimuth angles were measured at intervals of 50 mm toward both ends in the longitudinal direction. In the measurement, the film was cut to 1300 mm and 300 mm in the width direction and the film flow direction, respectively, and the center point of the 300 x 200 mm area was used as the measurement point.
Deviation (°) from the average value of the main axis azimuth angle is calculated by subtracting the main axis azimuth angle at each measurement point from the average value of the measured main axis azimuth angle, and the value with the largest absolute value is the deviation from the average value of the main axis azimuth angle. calculated as
As for the multilayer film, the main axis azimuth angle was measured from the high hardness resin layer ((meth)acrylic resin layer) side.

<Phase difference>
For the retardation of the polycarbonate resin film and multilayer film, the maximum in-plane retardation at a measurement wavelength of 520 nm was measured. The unit is nm.
PA-300 manufactured by Photonic Lattice was used to measure the phase difference. The film was placed so that the direction perpendicular to the longitudinal direction was directed from the front to the back of the device. As for the measurement points of the apparatus, the center point connecting the diagonals of the film was used as the center point, and the retardation was measured at intervals of 50 mm toward both ends in the longitudinal direction. Among these, the highest phase difference was taken as the phase difference in the present invention.
For the multilayer film, the retardation was measured from the high hardness resin layer ((meth)acrylic resin layer) side.

<Thickness of multilayer film>
The thickness of the multilayer film was measured by a method based on JIS K 7130 A method.

Example 1
A multi-layer extruder having a single-screw extruder with a shaft diameter of 50 mm, a single-screw extruder with a shaft diameter of 100 mm, a feed block connected to all the extruders, and a T-die with a width of 1500 mm connected to the feed block. A multilayer film was formed by A (meth)acrylic resin (manufactured by Arkema Co., Ltd., trade name Altuglas V020, composition: polymethyl methacrylate) was continuously introduced as a high-hardness resin into a single-screw extruder with a shaft diameter of 50 mm, and extruded at a cylinder temperature of 240°C. Further, a polycarbonate resin (manufactured by Mitsubishi Engineering-Plastics, trade name: Iupilon S-1000, bisphenol A type polycarbonate resin, weight average molecular weight: 59000) was continuously introduced into a single screw extruder with a shaft diameter of 100 mm, and the cylinder temperature was Extruded at 280°C. A single-screw extruder with a shaft diameter of 50 mm and a single-screw extruder with a shaft diameter of 100 mm were set so that the discharge amount ratio was 35/90. A feed block connected to the entire extruder was equipped with a two-kind and two-layer distribution pin, and the temperature was set to 270° C. to introduce and laminate the high hardness resin and the polycarbonate resin. It was extruded onto a film with a T-die connected to the end thereof and having a temperature of 270°C. In the film manufacturing apparatus using rolls as shown in FIG. It was cooled while transferring the mirror surface with a book mirror-finishing roll. At that time, the contact distance between the first cooling roll 23 and the second cooling roll 25 was 305 mm, the contact length between the multilayer film and the second cooling roll 25 was 40 mm, and the first cooling roll Set the line speed so that the peripheral speed ratio of the take-up roll (third roll) 26 is 0.991, and the total thickness (hereinafter referred to as the total thickness) of the polycarbonate resin and (meth)acrylic resin layer is 125 μm, A multilayer film was obtained. The thickness of the (meth)acrylic resin layer of the obtained multilayer film was 35 μm near the center. The polycarbonate resin layer side is in contact with the second cooling roll.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 2
A single-screw extruder with a shaft diameter of 50 mm and a single-screw extruder with a shaft diameter of 100 mm have a discharge rate ratio of 40/140, a peripheral speed ratio of the take-up roll 26 to the first cooling roll 23 is 0.985, and a multilayer film A multilayer film was obtained in the same manner as in Example 1, except that the total thickness of was set to 180 μm. The thickness of the (meth)acrylic resin layer was 40 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 3
A single-screw extruder with a shaft diameter of 50 mm and a single-screw extruder with a shaft diameter of 100 mm have a discharge rate ratio of 55/199, a peripheral speed ratio of the take-up roll 26 to the first cooling roll 23 is 0.985, and a multilayer film A multilayer film was obtained in the same manner as in Example 1, except that the total thickness of was set to 254 μm. The thickness of the (meth)acrylic resin layer was 55 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 4
A single-screw extruder with a shaft diameter of 50 mm and a single-screw extruder with a shaft diameter of 100 mm have a discharge rate ratio of 55/320, a peripheral speed ratio of the take-up roll 26 to the first cooling roll 23 is 0.985, and a multilayer film A multilayer film was obtained in the same manner as in Example 1, except that the total thickness of was set to 375 μm. The thickness of the (meth)acrylic resin layer was 55 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 5
Same as Example 4, except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was set to 320 mm, and the contact length between the multilayer film and the second cooling roll was set to 310 mm. to obtain a multilayer film.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 6
The distance between the contacts between the first cooling roll 23 and the second cooling roll 25 was set to 205 mm, and the contact length between the multilayer film and the second cooling roll 25 was set to 60 mm. A multilayer film was obtained in the same manner as in Example 4.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 7
A single-screw extruder with a shaft diameter of 50 mm and a single-screw extruder with a shaft diameter of 100 mm have a discharge rate ratio of 55/445, a peripheral speed ratio of the take-up roll 26 to the first cooling roll 23 is 0.985, and a multilayer film A multilayer film was obtained in the same manner as in Example 1, except that the total thickness of was set to 500 μm. The thickness of the (meth)acrylic resin layer was 55 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 8
On the surface of the (meth)acrylic resin layer of the multilayer film (total thickness: 180 μm, (meth)acrylic resin layer: 40 μm) produced in Example 2, a UV-curable urethane acrylate hard coat was applied using a roll coating method. (UV curable urethane acrylate manufactured by Mitsubishi Chemical, trade name UV-7650B) was coated to a thickness of 5 μm to obtain a multilayer film.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 9
On the surface of the (meth)acrylic resin layer of the multilayer film produced in Example 4 (total thickness: 375 μm, (meth)acrylic resin layer thickness: 55 μm), a UV-curable urethane acrylate hard coat was applied using a roll coating method. (UV curable urethane acrylate manufactured by Mitsubishi Chemical, trade name UV-7650B) was coated to a thickness of 5 μm to obtain a multilayer film.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 1
Same as Example 1 except that the distance between the contacts between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the multilayer film and the distance between the contacts of the second cooling roll 25 was 190 mm. to obtain a multilayer film. The total thickness of the multilayer film was 125 μm, and the thickness of the (meth)acrylic resin layer was 35 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 2
The multilayer film was formed in the same manner as in Example 3, except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the multilayer film and the second cooling roll 25 was 190 mm. got the film. The total thickness of the multilayer film was 254 μm, and the thickness of the (meth)acrylic resin layer was 55 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 3
The multilayer film was formed in the same manner as in Example 4 except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the multilayer film and the second cooling roll 25 was 190 mm. got the film. The total thickness of the multilayer film was 375 µm, and the thickness of the (meth)acrylic resin layer was 55 µm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 4
The multilayer film was formed in the same manner as in Example 7, except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the multilayer film and the second cooling roll 25 was 190 mm. got the film. The total thickness of the multilayer film was 500 μm, and the thickness of the (meth)acrylic resin layer was 55 μm near the center.
With respect to the obtained multilayer film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 10
A polycarbonate resin film was molded using an extruder having a single-screw extruder with a shaft diameter of 100 mm and a T-die with a width of 1500 mm connected to the extruder. Polycarbonate resin (manufactured by Mitsubishi Engineering-Plastics, trade name: Iupilon S-1000, bisphenol A type polycarbonate resin, weight average molecular weight: 59000) was continuously introduced as thermoplastic resin A into a single-screw extruder having a shaft diameter of 100 mm. , extruded at a cylinder temperature of 280°C. A single-screw extruder with a shaft diameter of 100 mm was set to have a discharge rate of 200 kg/h, and a T-die at a temperature of 270° C. was used to extrude onto a film. The roll temperature of the touch roll 22 is 100°C, the roll temperature of the first cooling roll 23 is 100°C, and the roll temperature of the second cooling roll 25 is 140°C. bottom. At that time, the contact distance between the first cooling roll 23 and the second cooling roll 25 was 305 mm, the contact length between the polycarbonate resin film and the second cooling roll 25 was 40 mm, and the first cooling roll 23 A polycarbonate resin film was obtained by setting the peripheral speed ratio of the take-up roll 26 to 0.985 and setting the line speed so that the thickness of the polycarbonate resin film was 100 μm.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 11
A polycarbonate resin film was obtained in the same manner as in Example 10, except that the discharge rate of the single screw extruder with a shaft diameter of 100 mm was 300 kg/h, and the line speed was set so that the thickness of the polycarbonate resin film was 254 μm.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 12
A polycarbonate resin film was obtained in the same manner as in Example 10, except that the discharge rate of the single screw extruder with a shaft diameter of 100 mm was 300 kg/h, and the line speed was set so that the thickness of the polycarbonate resin film was 375 μm.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Example 13
A polycarbonate resin film was obtained in the same manner as in Example 10, except that the discharge rate of the single screw extruder with a shaft diameter of 100 mm was 300 kg/h, and the line speed was set so that the thickness of the polycarbonate resin film was 500 μm.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 5
The procedure of Example 10 was repeated except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the polycarbonate resin film and the second cooling roll 25 was 190 mm. A polycarbonate resin film was obtained.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 6
The procedure of Example 11 was repeated except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the polycarbonate resin film and the second cooling roll 25 was 190 mm. A polycarbonate resin film was obtained.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 7
In the same manner as in Example 12, except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the polycarbonate resin film and the second cooling roll 25 was 190 mm. A polycarbonate resin film was obtained.
For the obtained polycarbonate resin film, the pencil hardness, the average principal axis azimuth angle, the deviation from the average principal axis azimuth angle, and the phase difference were measured and calculated.

Comparative example 8
In the same manner as in Example 13, except that the contact distance between the first cooling roll 23 and the second cooling roll 25 was 41 mm, and the contact length between the polycarbonate resin film and the second cooling roll 25 was 190 mm. A polycarbonate resin film was obtained.

As is clear from the above results, the multilayer film of the present invention had a low retardation property and a uniform principal axis orientation despite having a polycarbonate resin film using PC-A as a raw material. In addition, the polycarbonate resin film of the present invention had a low retardation property and a uniform principal axis orientation although PC-A was used as a raw material.

1 polycarbonate resin film 2 other layer 21 T-die 22 touch roll 23 first cooling roll 24 polycarbonate resin film in the process of production 25 second cooling roll 26 third roll 30 contact length

Claims

A polycarbonate resin film containing a polycarbonate resin and satisfying the following conditions 1 to 3;
Condition 1: Polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1);
Condition 2: the deviation from the average value of the main axis azimuth angle of the film is within ±11°;
Condition 3: The film has a retardation of 5 to 50 nm.
formula (1)
2. The polycarbonate resin film according to claim 1, wherein the polycarbonate resin film has a thickness of 50 to 1500 μm.
Having a polycarbonate resin film and at least one other layer,
A multilayer film that satisfies the following conditions A to C;
Condition A polycarbonate resin is a structural unit whose main structural unit is represented by the following formula (1);
Condition B: the deviation from the average value of the main axis azimuth angle of the film is within ±11°;
Condition C: The film has a retardation of 5 to 50 nm.
formula (1)
4. The multilayer film according to claim 3, wherein the pencil hardness measured from the other layer side of the multilayer film is HB or higher.
5. The multilayer film according to claim 3, wherein the polycarbonate resin film and the other layer have a total thickness of 50 to 1500 μm.
The multilayer film according to any one of claims 3 to 5, wherein the polycarbonate resin film and the other layer have a thickness ratio of 2/1 to 10/1.
7. The multilayer film according to claim 5, wherein the other layer has a thickness of 20-100 μm.
The multilayer film according to any one of Claims 3 to 7, wherein the other layer is a layer containing a (meth)acrylic resin.
A multilayer film comprising a hard coat layer on one side or both sides of the polycarbonate resin film according to claim 1 or 2 or the multilayer film according to any one of claims 3 to 8.
A multilayer film having a masking film on one side or both sides of the polycarbonate resin film of claim 1 or 2 or the multilayer film of any one of claims 3-9.
A display device comprising the polycarbonate resin film according to claim 1 or 2 and/or the multilayer film according to any one of claims 3 to 10.
3. The method for producing a polycarbonate resin film according to claim 1 or 2, wherein the distance between the roll-to-roll points of the first cooling roll and the second cooling roll in the direction perpendicular to the rotation axis direction of the rolls is A method for producing a polycarbonate resin film having a thickness of 160 to 450 mm.
13. The method for producing a polycarbonate resin film according to claim 12, wherein the peripheral speed ratio between the first cooling roll and the take-up roll is 1:0.995 to 1:0.975.
14. The method for producing a polycarbonate resin film according to claim 12 or 13, comprising extruding the resin composition for forming a polycarbonate resin film through a T-die, wherein the T-die has a width of 600 mm or more.
15. The length of contact between the second cooling roll and the semi-molten polycarbonate resin film in the direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm, according to any one of claims 12 to 14. The method for producing a polycarbonate resin film according to 1.
The method for producing a multilayer film according to any one of claims 3 to 8, wherein the inter-roll contact between the first chill roll and the second chill roll in the direction perpendicular to the rotation axis direction of the rolls A method for producing a multilayer film, wherein the inter-layer distance is 160-450 mm.
17. The method for producing a multilayer film according to claim 16, wherein the peripheral speed ratio between the first cooling roll and the take-up roll is 1:0.995 to 1:0.975.
18. The multilayer film according to claim 16 or 17, comprising extruding the resin composition for forming the polycarbonate resin film and the resin composition for forming other layers from a T-die, wherein the T-die has a width of 600 mm or more. manufacturing method.
The length of contact between the second cooling roll and the semi-molten multilayer film in a direction perpendicular to the rotation axis direction of the roll is 2 to 400 mm, according to any one of claims 16 to 18. A method of making the multilayer film described.
The method for producing a multilayer film according to any one of claims 16 to 19, wherein the other layer is a layer containing a (meth)acrylic resin.