CN113183575A

CN113183575A - Film roll

Info

Publication number: CN113183575A
Application number: CN202110104703.9A
Authority: CN
Inventors: 藤长将司; 西冈宏司
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2020-01-29
Filing date: 2021-01-26
Publication date: 2021-07-30
Also published as: TW202138198A

Abstract

The present invention relates to a roll of film. The present invention provides a method for preventing curling from occurring or reducing curling even when a laminated film is transported or conveyed in a film roll form. The present invention provides a film roll formed by winding a laminated film and a protective film 1, wherein the laminated film comprises: an optical film comprising a polyimide resin and/or a polyamide resin, and a functional cured resin layer laminated on the optical film; the protective film 1 is laminated on the opposite side of the cured resin layer from the optical film, and the film roll is wound from the core side of the roll in the order of the optical film, the cured resin layer, and the protective film 1.

Description

Film roll

Technical Field

The present invention relates to a film roll formed by winding a laminated film, and more particularly to a film roll in which curling is not easily generated when the laminated film is unwound.

Background

A laminated film in which an optical film containing a polyimide resin and/or a polyamide resin and a cured resin layer having a specific function are laminated has been used in various fields. For example, in accordance with the reduction in thickness, weight, flexibility, and the like of displays of various image display devices, a laminated film in which an optical resin film layer containing a polyimide-based resin and/or a polyamide-based resin is laminated with a hard coat layer has been used as a material replacing glass that has been conventionally used.

Generally, these laminated films are wound around a winding core after the laminated films are manufactured, and are transported and conveyed as a film roll. Of course, when a laminated film is used, the film is unwound from a film roll and used as a flat laminated film.

However, when the film roll is unwound and used, curling may occur. The curl means that when one surface of the laminated film is placed on a plane, the end of the laminated film is separated from the plane. When the laminated film is curled, it is difficult to use the laminated film as it is, and therefore, it is necessary to perform a work of returning the laminated film to a state without curling, which causes a loss in work and deteriorates work efficiency. When the film is used in a planar state when curling occurs, a force acting to separate the film from the plane acts, and an adverse effect on a product using the laminated film is considered. Specifically, there are the following problems: when the film is adhered to another member, the curled portion is not satisfactorily adhered to the other member, and air bubbles are caught, or when the film is adhered to the other member while sucking, if the curl is strong, the film cannot be sucked and is peeled from the suction portion, and an error occurs, and the apparatus is stopped. The laminated film is formed into a film roll during transportation and conveyance, but when the laminated film is unwound and used, it is preferable that no curling occurs.

Patent document 1 discloses a printing plate material having a hydrophilic layer on a support, wherein the support is formed of a plastic film and has a rising curl of 0mm to 60 mm. Patent document 1 proposes a method of reducing curl, but this method is a method of performing sequential biaxial stretching after casting (that is, stretching in the longitudinal direction and then further stretching in the transverse direction), and requires a stretching operation in the production, which increases the production cost.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-74502

Disclosure of Invention

Problems to be solved by the invention

The present invention aims to provide a simple method for preventing or reducing curling during unwinding even when a laminated film is transported or conveyed in a film roll form.

Means for solving the problems

Namely, the present invention provides: a film roll formed by winding a laminate including a laminated film and a protective film 1, the laminated film including:

an optical film comprising a polyimide-based resin and/or a polyamide-based resin, and

a cured resin layer laminated on the optical film;

the protective film 1 is laminated on the opposite side of the cured resin layer from the optical film,

the film roll is wound from the core side of the roll in the order of the optical film, the cured resin layer, and the protective film 1.

The present invention also provides the following means:

the present invention also provides a film roll formed by winding up a laminate, the laminate including:

a laminated film comprising an optical film containing a polyimide-based resin and/or a polyamide-based resin,

a cured resin layer laminated on the optical film,

a protective film 1, the protective film 1 being laminated on a side of the cured resin layer opposite to the optical film,

a protective film 2, the protective film 2 being laminated on a side of the optical film opposite to the cured resin layer,

the film roll is wound from the core side of the roll in the order of the protective film 2, the optical film, the cured resin layer, and the protective film 1.

The cured resin layer has 1 or more functions selected from the group consisting of a hard coat function, an antistatic function, an antiglare function, a low reflection function, an antireflection function, and an antifouling function.

The cured resin layer is a UV cured resin layer.

ADVANTAGEOUS EFFECTS OF INVENTION

In the present invention, the curling of the laminated film can be prevented only by specifying the order in winding the laminate around the core, and particularly, the curling can be prevented easily without affecting the manufacturing method and the like. In particular, curling during storage, transportation, and transportation in a high-temperature environment can be suppressed.

The curl in the present invention means a curl when a film roll is stored in a high-temperature environment, particularly in a high-temperature dry environment. In the present application, the high temperature environment refers to a temperature environment of about 40 to 100 ℃, and the dry environment refers to an environment having a relative humidity of 0 to 60%.

Detailed Description

The present invention is characterized in that in a film roll in which a laminated film including an optical film comprising a polyimide-based resin and/or a polyamide-based resin, a cured resin layer laminated on the optical film, and a protective film 1 laminated on the cured resin layer on the side opposite to the optical film is wound around a winding core, the lamination order when the laminated film is wound around the winding core is in the order of the optical film, the cured resin layer, and the protective film 1 from the core side of the roll. The protective film may be present on the opposite side of the optical film from the cured resin layer, and in this case, the protective film 2, the optical film, the cured resin layer, and the protective film 1 are wound in this order from the core side of the roll. Hereinafter, each configuration will be described.

< optical film >

The optical film constituting the laminated film of the present invention contains a polyimide-based resin and/or a polyamide-based resin.

In the present specification, the polyimide-based resin means at least 1 resin selected from the group consisting of a polyimide resin, a polyamideimide resin, a polyimide precursor resin, and a polyamideimide precursor resin. The polyimide resin is a resin containing a repeating structural unit containing an imide group, and the polyamideimide resin is a resin containing a repeating structural unit containing both an imide group and an amide group. The polyimide precursor resin and the polyamideimide precursor resin are precursors before imidization, which provide the polyimide resin and the polyamideimide resin, respectively, by imidization, and are also called polyamic acids. In the present specification, the polyamide resin is a resin containing a repeating structural unit containing an amide group. The optical film of the present invention may contain 1 kind of polyimide-based resin or polyamide-based resin, or may contain 2 or more kinds of polyimide-based resins and/or polyamide-based resins in combination. The optical film of the present invention preferably contains a polyimide-based resin, preferably a polyimide resin or a polyamideimide resin, more preferably a polyamideimide resin, from the viewpoint of easily achieving both chemical stability and curl resistance of the optical film.

In a preferred embodiment of the present invention, the polyimide-based resin and the polyamide-based resin are preferably aromatic resins from the viewpoint of facilitating further improvement in the elastic modulus and the curl resistance of the optical film. In the present specification, the aromatic resin means a resin in which the structural units contained in the polyimide resin and the polyamide resin are mainly aromatic structural units.

In the preferred embodiment described above, the proportion of the structural unit derived from the aromatic monomer to the total structural units contained in the polyimide-based resin and the polyamide-based resin is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 85 mol% or more, from the viewpoint of facilitating further improvement in the elastic modulus and the curl resistance of the optical film. Here, the structural unit derived from an aromatic monomer is a structural unit derived from a monomer at least a part of which contains an aromatic structure (for example, an aromatic ring) and at least a part of which contains an aromatic structure (for example, an aromatic ring). Examples of the aromatic monomer include aromatic tetracarboxylic acid compounds, aromatic diamines, and aromatic dicarboxylic acids.

In a preferred embodiment of the present invention, the polyimide-based resin is preferably a polyimide resin having a structural unit represented by formula (1) or a polyamideimide resin having a structural unit represented by formula (1) and a structural unit represented by formula (2).

[ chemical formula 1]

[ in formula (1), Y represents a 4-valent organic group, X represents a 2-valent organic group, and X represents a bond ]

[ chemical formula 2]

[ in the formula (2), Z and X independently represent a 2-valent organic group, and represent a bond ]

The polyamide resin is preferably a polyamide resin having a structural unit represented by formula (2). The following are descriptions of formula (1) and formula (2), the description of formula (1) relating to both polyimide resin and polyamideimide resin, and the description of formula (2) relating to both polyamide resin and polyamideimide resin.

The structural unit represented by formula (1) is a structural unit formed by reacting a tetracarboxylic acid compound with a diamine compound, and the structural unit represented by formula (2) is a structural unit formed by reacting a dicarboxylic acid compound with a diamine compound.

In the formula (2), Z is a 2-valent organic group, preferably a4 to about C organic group which may be substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms in which hydrogen atoms may be substituted with a halogen atom (preferably a fluorine atom)The (40) organic group having a valence of 2 is more preferably an organic group having a valence of 2 and having a carbon number of 4 to 40, which group has a cyclic structure and may be substituted with an alkyl group having a carbon number of 1 to 6, an alkoxy group having a carbon number of 1 to 6, or an aryl group having a carbon number of 6 to 12 (hydrogen atoms in these groups may be substituted with a halogen atom (preferably a fluorine atom)). As examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, or the aryl group having 6 to 12 carbon atoms, R in the formula (3) described later can be similarly applied^3aAnd R^3bExamples of (2). Examples of the cyclic structure include alicyclic, aromatic ring, and heterocyclic structure. Examples of the organic group of Z include a group obtained by replacing 2 nonadjacent groups in the chemical bonds of the groups represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29) with a hydrogen atom, a 2-valent chain hydrocarbon group having 6 or less carbon atoms,

[ chemical formula 3]

In [ formula (20) to formula (29), W¹Represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-Ar-、-SO₂-、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂-Ar-、-Ar-C(CH₃)₂-Ar-or-Ar-SO₂Ar-wherein Ar independently represents an arylene group having 6 to 20 carbon atoms (for example, phenylene group) in which hydrogen atoms may be substituted with fluorine atoms, and represents a bond]

Examples of the heterocyclic structure of Z include a group having a thiophene ring skeleton. From the viewpoint of easily lowering the YI value, which is an index of the yellowness of the optical film, the groups represented by formulae (20) to (29) and the group having a thiophene ring skeleton are preferable, and the groups represented by formulae (26), (28) and (29) are more preferable.

As the organic group of Z, 2-valent organic groups represented by formula (20 '), formula (21'), formula (22 '), formula (23'), formula (24 '), formula (25'), formula (26 '), formula (27'), formula (28 ') and formula (29') are more preferable.

[ chemical formula 4]

In [ formulae (20 ') to (29'), W¹And as defined in formulas (20) to (29)]

The hydrogen atom on the ring in the formulae (20) to (29) and (20 ') to (29') may be substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, in which the hydrogen atom may be substituted with a halogen atom (preferably, a fluorine atom).

When the polyamide resin or polyamideimide resin has a structural unit wherein Z in formula (2) is represented by any one of formulae (20 ') to (29 '), and particularly when Z in formula (2) is represented by formula (3 ') described later, it is preferable that the polyamide resin or polyamideimide resin has not only the structural unit but also a structural unit derived from a carboxylic acid represented by formula (d1) described below from the viewpoint of easily improving the film-forming property of the varnish and easily improving the uniformity of the optical film.

[ chemical formula 5]

[ in the formula (d1), R²⁴Is R in the following formula (3)^3aA group as defined or a hydrogen atom, R²⁵Represents R²⁴or-C (═ O) -, denotes a bond]

Specific examples of the structural unit (d1) include R²⁴And R²⁵Structural units each of which is a hydrogen atom (structural units derived from a dicarboxylic acid compound), R²⁴Are all hydrogen atoms and R²⁵A structural unit (structural unit derived from a tricarboxylic acid compound) representing — C (═ O) -, and the like.

In the polyamide resin or the polyamideimide resin, a plurality of types of Z may be contained as Z in the formula (2), and the plurality of types of Z may be the same or different from each other. Among them, from the viewpoint of easily improving the elastic modulus and the curl resistance of the optical film of the present invention and easily improving the optical characteristics, it is preferable that Z in formula (2) has at least a structural unit represented by formula (3) or more preferably formula (3').

[ chemical formula 6]

[ in the formula (3), R^3aAnd R^3bIndependently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, R^3aAnd R^3bThe hydrogen atoms contained in (a) may be substituted independently of each other by halogen atoms,

w independently of one another represent a single bond, -O-, -CH₂-、-CH2-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-N (R)⁹)-，R⁹A 1-valent hydrocarbon group having 1 to 12 carbon atoms which is a hydrogen atom or a halogen atom-substituted hydrocarbon group,

s is an integer of 0 to 4, t is an integer of 0 to 4, and u is an integer of 0 to 4

[ chemical formula 7]

[ formula (3') wherein R^3a、R^3bS, t, u, W and as defined in formula (3)]

In the present specification, the phrase "the polyamide resin or the polyamideimide resin has a structural unit represented by formula (3) in which Z in formula (2) is represented by" and the phrase "the polyamide resin or the polyamideimide resin has a structure represented by formula (3) as Z in formula (2)" has the same meaning, means that Z in at least a part of the structural units in the plurality of structural units represented by formula (2) contained in the polyamide resin or the polyamideimide resin is represented by formula (3). This description is also applicable to other similar descriptions.

In the formulae (3) and (3'), W independently represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-N (R)⁹) From the viewpoint of the bending resistance of the optical film, the compound preferably represents-O-or-S-, and more preferably represents-O-.

R^3aAnd R^3bIndependently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a 2-methyl-butyl group, a 3-methylbutyl group, a 2-ethylpropyl group, and a n-hexyl group. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a cyclohexyloxy group, and the like. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group. From the viewpoint of surface hardness and flexibility of the optical film, R^3aAnd R^3bIndependently of each other, the alkyl group preferably has 1 to 6 carbon atoms, and more preferably has 1 to 3 carbon atoms. Here, R^3aAnd R^3bThe hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other.

R⁹Represents a hydrogen atom, a C1-12 hydrocarbon group which may be substituted with a halogen atom. Examples of the C1-valent hydrocarbon group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-methylbutyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, and tert-butylOctyl, n-nonyl, n-decyl and the like, which may be substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like.

In the formulae (3) and (3'), t and u are each independently an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.

In the formula (3) and the formula (3'), s is an integer in the range of 0 to 4, and s is in the above range, the curl resistance, elastic modulus and bending resistance of the optical film are easily improved. From the viewpoint of facilitating further improvement in curl resistance, elastic modulus, and bending resistance of the optical film, s is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, further preferably 0 or 1, and particularly preferably 0. The structural unit represented by formula (3) or formula (3 ') wherein s is 0 is, for example, a structural unit derived from terephthalic acid or isophthalic acid, and the structural unit is preferably a structural unit wherein s is 0 and u is 0 in formula (3) or formula (3'). The polyamideimide resin or the polyamide resin preferably contains a structural unit derived from terephthalic acid from the viewpoint of easily improving the curl resistance, the elastic modulus, and the bending resistance of the optical film. The polyamideimide resin or the polyamide-based resin may contain 1 or 2 or more kinds of the structural unit represented by the formula (3) or the formula (3') in Z. From the viewpoint of improving the curl resistance, elastic modulus, and bending resistance of the optical film, and reducing the YI value, the polyamideimide resin or the polyamide-based resin preferably contains 2 or more structural units different in the value of s in formula (3) or formula (3 ') in Z, and more preferably contains 2 or 3 structural units different in the value of s in formula (3) or formula (3'). In this case, from the viewpoint of easily improving the curl resistance, elastic modulus, and bending resistance of the optical film and from the viewpoint of easily reducing the YI value of the optical film, the polyamideimide resin or the polyamide resin contains a structure represented by formula (3) in which s is 0 as Z in the structural unit represented by formula (2), and more preferably contains not only the structural unit containing the structure but also the structural unit containing the structure represented by formula (3) in which s is 1. It is also preferable that the functional group has not only the structural unit represented by formula (2) containing Z represented by formula (3) in which s is 0 but also the structural unit represented by formula (d1) described above.

In a preferred embodiment of the present invention, the polyamideimide resin or the polyamide resin has a structural unit in which s is 0 and u is 0 as the structural unit represented by formula (3) or formula (3'). In a more preferred embodiment of the present invention, the polyamideimide resin or the polyamide resin has a structural unit represented by formula (3) or formula (3') which includes a structural unit having s ═ 0 and u ═ 0 and a structural unit represented by formula (3 ″).

[ chemical formula 8]

In this case, not only the curl resistance, elastic modulus and bending resistance of the optical film are easily improved, but also the YI value is easily reduced.

When the polyamideimide resin or the polyamide resin has the structural unit represented by the formula (3) or the formula (3'), the proportion thereof is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 40 mol% or more, further more preferably 50 mol% or more, particularly preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, and further preferably 80 mol% or less, when the total of the structural unit represented by the formula (1) and the structural unit represented by the formula (2) of the polyamideimide resin or the polyamide resin is taken as 100 mol%. When the proportion of the structural unit represented by formula (3) or formula (3') is not less than the above lower limit, the curl resistance, elastic modulus, and bending resistance of the optical film are easily improved. When the proportion of the structural unit represented by formula (3) or formula (3') is not more than the above upper limit, the increase in viscosity of the varnish containing the resin due to hydrogen bonding between amide bonds derived from formula (3) is easily suppressed, and the film processability is easily improved.

When the polyamideimide resin or the polyamide resin has a structural unit represented by formula (3) or formula (3') wherein s is 1 to 4, the structural unit represented by formula (1) of the polyamideimide resin or the polyamide resin and the formula (2) are shown in the tableThe proportion of the structural unit represented by formula (3) or formula (3') having s of 1 to 4 is preferably 3 mol% or more, more preferably 5 mol% or more, further preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 50 mol% or less, and particularly preferably 30 mol% or less, when the total of the structural units shown is 100 mol%. When the proportion of the structural unit represented by formula (3) or formula (3') in which s is 1 to 4 is not less than the above lower limit, the curl resistance, elastic modulus, and bending resistance of the optical film are easily improved. When the proportion of the structural unit represented by formula (3) in which s is 1 to 4 is not more than the upper limit, the viscosity of the varnish containing the resin is easily prevented from increasing due to hydrogen bonding between amide bonds derived from the structural unit represented by formula (3) or formula (3'), and the processability of the film is easily improved. The proportion of the structural unit represented by formula (1), formula (2), formula (3) or formula (3') may be, for example, the one represented by¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In a preferred embodiment of the present invention, Z in the polyamideimide resin or the polyamide resin is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more, and still more preferably 50 mol% or more of the structural unit represented by the formula (3) or the formula (3') in which s is 0 to 4. When the lower limit of Z is not less than the above-mentioned limit and s is 0 to 4, the structural unit represented by formula (3) or formula (3') can easily improve the curl resistance, elastic modulus and bending resistance of the optical film. Further, the structural unit represented by the formula (3) or (3') in which 100 mol% or less of Z in the polyamideimide resin or the polyamide resin is s 0 to 4 may be used. The proportion of the structural unit represented by the formula (3) or (3') wherein s is 0 to 4 in the resin can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In a preferred embodiment of the present invention, Z in the polyamideimide resin or the polyamide resin is represented by formula (3) or formula (3') wherein s is 1 to 4, preferably 5 mol% or more, more preferably 8 mol% or more, further preferably 10 mol% or more, and particularly preferably 12 mol% or more.When the above lower limit or more of Z of the polyamideimide resin or the polyamide-based resin is represented by formula (3) or formula (3') wherein s is 1 to 4, the curl resistance, elastic modulus and bending resistance of the optical film are easily improved. In addition, preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 50 mol% or less, and particularly preferably 30 mol% or less of Z is represented by formula (3) or formula (3') with s of 1 to 4. When the above upper limit or less of Z is represented by formula (3) in which s is 1 to 4, the viscosity of the varnish containing the resin is easily prevented from increasing due to hydrogen bonding between amide bonds derived from the structural unit represented by formula (3) or formula (3') in which s is 1 to 4, and the processability of the film is easily improved. The proportion of the structural unit represented by the formula (3) or (3') wherein s is 1 to 4 in the resin can be, for example, the one represented by¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In the formulae (1) and (2), X independently represents a 2-valent organic group, preferably a 2-valent organic group having 4 to 40 carbon atoms, and more preferably a 2-valent organic group having a cyclic structure and having 4 to 40 carbon atoms. Examples of the cyclic structure include alicyclic, aromatic ring, and heterocyclic structure. The organic group may have hydrogen atoms substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the number of carbon atoms in the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. In one embodiment of the present invention, the polyamideimide resin of the present invention may contain a plurality of kinds of X, and the plurality of kinds of X may be the same as or different from each other. Examples of X may include groups represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18); a group obtained by substituting a hydrogen atom in the group represented by the formula (10) to the formula (18) with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

[ chemical formula 9]

In the formulae (10) to (18), represents a bond,

V¹、V²and V³Independently of each other, represents a single bond, -O-, -S-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)2-、-SO₂-, -CO-or-N (Q) -. Wherein Q represents a C1-12 hydrocarbon group which may be substituted with a halogen atom. Examples of the C1-valent hydrocarbon group include R⁹But the groups described hereinbefore.

1 example is, V¹And V³Is a single bond, -O-or-S-, and V²is-CH₂-、-C(CH₃)₂-、-C(CF₃)₂-or-SO₂-。V¹And V²Bonding position with respect to each ring, and V²And V³The bonding position to each ring is preferably meta-or para-position, and more preferably para-position, independently from each ring.

Among the groups represented by formulae (10) to (18), from the viewpoint of easily improving the curl resistance, elastic modulus and bending resistance of the optical film, the groups represented by formulae (13), (14), (15), (16) and (17) are preferable, and the groups represented by formulae (14), (15) and (16) are more preferable. In addition, from the viewpoint of easily improving the curl resistance, elastic modulus and flexibility of the optical film, V¹、V²And V³Independently of one another, are preferably single bonds, -O-or-S-, more preferably single bonds or-O-.

In a preferred embodiment of the present invention, the polyamide resin and the polyimide resin contain a structure represented by formula (4) as X in formula (1) or X in formula (2).

[ chemical formula 10]

[ in the formula (4), R¹⁰～R¹⁷Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁰～R¹⁷Hydrogen contained inThe atoms being, independently of one another, substitutable by halogen atoms, representing a bond]

When at least a part of X in the plurality of structural units represented by formulas (1) and (2) is represented by formula (4), the curl resistance, elastic modulus, and transparency of the optical film are easily improved.

In the formula (4), R¹⁰、R¹¹、R¹²、R¹³、R¹⁴、R¹⁵、R¹⁶And R¹⁷Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3). R¹⁰～R¹⁷Independently of each other, preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R¹⁰～R¹⁷The hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoint of curl resistance, elastic modulus, transparency and bending resistance of the optical film, R¹⁰～R¹⁷Independently of each other, a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group is more preferable, and R is more preferable¹⁰、R¹²、R¹³、R¹⁴、R¹⁵And R¹⁶Is a hydrogen atom, R¹¹And R¹⁷Is hydrogen, methyl, fluoro, chloro or trifluoromethyl, particularly preferably R¹¹And R¹⁷Is methyl or trifluoromethyl.

In a preferred embodiment of the present invention, the structural unit represented by formula (4) is a structural unit represented by formula (4'),

[ chemical formula 11]

That is, at least a part of X in the plurality of structural units represented by formulas (1) and (2) is a structural unit represented by formula (4'). In this case, the fluorine element-containing skeleton makes it easy to improve the solubility of the polyimide-based resin or the polyamide-based resin in a solvent, to improve the storage stability of the varnish containing the resin, to reduce the viscosity of the varnish, and to improve the processability of the optical film. Further, the optical properties of the optical film are easily improved by the skeleton containing the fluorine element.

In a preferred embodiment of the present invention, X in the polyimide-based resin or the polyamide-based resin is represented by formula (4), particularly formula (4'), preferably 30 mol% or more, more preferably 50 mol% or more, and still more preferably 70 mol% or more. When X in the above range in the polyimide-based resin or polyamide-based resin is represented by formula (4), particularly formula (4'), the solubility of the resin in a solvent is easily improved by the skeleton containing a fluorine element in the obtained optical film, the storage stability of a varnish containing the resin is easily improved, and the viscosity of the varnish is easily reduced, and the processability of the optical film is easily improved. Further, the optical properties of the optical film are also easily improved by the skeleton containing the fluorine element. Preferably, 100 mol% or less of X in the polyimide-based resin or the polyamide-based resin is represented by formula (4), particularly formula (4'). X in the above resin may be formula (4), particularly formula (4'). The proportion of the structural unit represented by the formula (4) of X in the resin can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In the formula (1), Y represents a 4-valent organic group, preferably a 4-valent organic group having 4 to 40 carbon atoms, and more preferably a 4-valent organic group having 4 to 40 carbon atoms and having a cyclic structure. Examples of the cyclic structure include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure, and preferred examples thereof include an aromatic ring structure from the viewpoint of easiness in improvement of curl resistance and elastic modulus. The organic group is an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in this case, the number of carbon atoms in the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1 to 8. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of kinds of Y, and the plurality of kinds of Y may be the same or different from each other. Examples of Y include groups represented by the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29); a group represented by the formulae (20) to (29) wherein a hydrogen atom is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having a valence of 4 and 6 or less carbon atoms.

[ chemical formula 12]

In the formulae (20) to (29), W represents a bond¹Represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-Ar-、-SO₂-、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂-Ar-、-Ar-C(CH₃)₂-Ar-or-Ar-SO₂-Ar-. Ar represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and specific examples thereof include phenylene groups.

Among the groups represented by formulae (20) to (29), the group represented by formula (26), formula (28), or formula (29) is preferable, and the group represented by formula (26) is more preferable, from the viewpoint of easily improving the curl resistance, elastic modulus, and bending resistance of the optical film. In addition, from the viewpoint of easily improving the curl resistance, elastic modulus and bending resistance of the optical film and easily lowering the YI value of the optical film, W¹Independently of one another, are preferably single bonds, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-, more preferably a single bond, -O-, -CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-is more preferably a single bond, -C (CH)₃) 2-or-C (CF)₃)2-，Particularly preferably a single bond or-C (CF)₃)2-。

In a preferred embodiment of the present invention, preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more of Y in the polyimide-based resin is represented by formula (26). Y in the above range in the polyimide resin is represented by the formula (26), preferably W¹Is a single bond, -C (CH)₃)₂-or-C (CF)₃)₂-formula (26), more preferably W¹Is a single bond or-C (CF)₃) When the formula (26) of 2-represents, the curl resistance, elastic modulus and bending resistance of the optical film are easily improved, and the YI value of the optical film is easily reduced. The proportion of the structural unit represented by the formula (26) for Y in the polyimide resin can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In a preferred embodiment of the present invention, at least a part of Y in the plurality of formulas (1) is represented by formula (5) and/or formula (9).

[ chemical formula 13]

[ in the formula (5), R¹⁸～R²⁵Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁸～R²⁵Wherein the hydrogen atoms contained in (A) are independently substituted by halogen atoms]

[ chemical formula 14]

[ formula (9) wherein R³⁵～R⁴⁰Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R³⁵～R⁴⁰Wherein the hydrogen atoms contained in (A) are independently substituted by halogen atoms]

When at least a part of Y in the plurality of formulae (1) is represented by formula (5) and/or formula (9), the curl resistance, elastic modulus, and optical characteristics of the optical film are easily improved.

In the formula (5), R¹⁸、R¹⁹、R²⁰、R²¹、R²²、R²³、R²⁴And R²⁵Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms include the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms or the aryl group having 6 to 12 carbon atoms in the formula (3). R¹⁸～R²⁵Independently of each other, preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R¹⁸～R²⁵The hydrogen atoms contained in (a) may be substituted by halogen atoms independently of each other. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. R is a value that facilitates improvement of curl resistance, elastic modulus, and bending resistance of the optical film, and that facilitates improvement of transparency and maintenance of the transparency¹⁸～R²⁵Independently of each other, a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group is more preferable, and R is more preferable¹⁸、R¹⁹、R²⁰、R²³、R²⁴And R²⁵Is a hydrogen atom, R²¹And R²²Is hydrogen, methyl, fluoro, chloro or trifluoromethyl, particularly preferably R²¹And R²²Is methyl or trifluoromethyl.

In the formula (9), R is from the viewpoint of easily improving the curl resistance, elastic modulus and bending resistance of the optical film, and from the viewpoint of easily improving the transparency and easily maintaining the transparency³⁵～R⁴⁰Preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and still more preferably a hydrogen atom. Here, R³⁵～R⁴⁰The hydrogen atoms contained in (a) may be independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. As R³⁵～R⁴⁰In the above-mentioned examples, the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms are exemplified above.

In a preferred embodiment of the present invention, formula (5) is represented by formula (5 '), and formula (9) is represented by formula (9').

[ chemical formula 15]

That is, at least a part of the plurality of Y is represented by formula (5 ') and/or formula (9'). In this case, the curl resistance, elastic modulus, and bending resistance of the optical film are easily improved. When the formula (5) is represented by the formula (5'), the solubility of the polyimide-based resin in a solvent is easily improved by the skeleton containing a fluorine element, the storage stability of a varnish containing the resin is easily improved, the viscosity of the varnish is easily reduced, and the processability of the optical film is easily improved. Further, the optical properties of the optical film are easily improved by the skeleton containing the fluorine element.

In a preferred embodiment of the present invention, preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more of Y in the polyimide-based resin is represented by formula (5), particularly formula (5'). When Y in the above range in the polyimide-based resin is represented by formula (5), particularly formula (5'), the solubility of the polyimide-based resin in a solvent is easily improved by the skeleton containing a fluorine element, the viscosity of a varnish containing the resin is easily reduced, and the processability of an optical film is easily improved. Further, the optical properties of the optical film are easily improved by the skeleton containing the fluorine element. Preferably, 100 mol% or less of Y in the polyimide-based resin is represented by formula (5), particularly formula (5'). Y in the polyimide-based resin may be formula (5), particularly formula (5'). Y in the polyimide resin is represented by the formula (5)The ratio of the structural units of (A) can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In a preferred embodiment of the present invention, the plurality of structural units represented by formula (1) preferably include not only the structural unit represented by formula (5) but also a structural unit represented by formula (9). When Y further includes a structural unit represented by formula (9), the curl resistance and the elastic modulus of the optical film are easily further improved.

The polyimide-based resin may be a polyimide-based resin containing a structural unit represented by formula (30) and/or a structural unit represented by formula (31), or may be a polyimide-based resin containing not only the structural unit represented by formula (1) and, optionally, formula (2), but also the structural unit represented by formula (30) and/or the structural unit represented by formula (31).

[ chemical formula 16]

In the formula (30), Y¹Is a 4-valent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y¹Examples thereof may include groups represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29), groups represented by formula (20) to formula (29) wherein a hydrogen atom is substituted with a methyl, fluoro, chloro or trifluoromethyl group, and chain hydrocarbon groups having 4-valent carbon atoms of 6 or less. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of kinds of Y¹Plural kinds of Y¹May be the same or different from each other.

In the formula (31), Y²Is a 3-valent organic group, preferably an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y²Examples of the "substituent" may include 1 arbitrary of the chemical bonds of the groups represented by the above-mentioned formulae (20), (21), (22), (23), (24), (25), (26), (27), (28) and (29)A group obtained by substituting a hydrogen atom, and a chain hydrocarbon group having a carbon number of 6 or less and having a valence of 3. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of kinds of Y²Plural kinds of Y²May be the same or different from each other.

In the formulae (30) and (31), X¹And X²Independently of one another, a 2-valent organic group, preferably an organic group in which the hydrogen atom in the organic group may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As X¹And X²Examples of the "substituent" may include groups represented by the above-mentioned formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18); a group obtained by substituting a hydrogen atom in the group represented by the formula (10) to the formula (18) with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having 6 or less carbon atoms.

In one embodiment of the present invention, the polyimide-based resin is formed from a structural unit represented by formula (1) and/or formula (2), and optionally a structural unit represented by formula (30) and/or formula (31). In addition, from the viewpoint of easily improving the optical properties, curl resistance, elastic modulus, and bending resistance of the optical film, the proportion of the structural unit represented by formula (1) and formula (2) in the polyimide-based resin is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more, based on the total structural units represented by formula (1) and formula (2) and, in some cases, formula (30) and formula (31). In the polyimide-based resin, the proportion of the structural units represented by the formulae (1) and (2) is usually 100% or less based on all the structural units represented by the formulae (1) and (2) and, in some cases, the formulae (30) and/or (31). The above ratio can be used, for example¹H-NMR was measured, or it was calculated from the charge ratio of the raw materials.

In one embodiment of the present invention, the content of the polyimide-based resin and/or the polyamide-based resin in the optical film is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, further preferably 50 parts by mass or more, preferably 99.5 parts by mass or less, and more preferably 95 parts by mass or less, with respect to 100 parts by mass of the optical film. When the content of the polyimide-based resin and/or the polyamide-based resin is within the above range, the optical properties, curl resistance, and elastic modulus of the optical film are easily improved.

The weight average molecular weight of the polyimide-based resin and the polyamide-based resin is preferably 200,000 or more, more preferably 230,000 or more, further preferably 250,000 or more, further preferably 270,000 or more, and particularly preferably 280,000 or more in terms of standard polystyrene, from the viewpoint of easily improving the curl resistance, the elastic modulus, and the bending resistance of the optical film. The weight average molecular weight of the polyimide-based resin and the polyamide-based resin is preferably 1,000,000 or less, more preferably 800,000 or less, even more preferably 700,000 or less, and particularly preferably 500,000 or less, from the viewpoint of easily improving the solubility of the resin in a solvent and easily improving the stretchability and processability of the optical film. The weight average molecular weight can be determined, for example, by measurement by gel permeation chromatography (hereinafter, sometimes referred to as GPC) and conversion to standard polystyrene, and can be calculated, for example, by the method described in examples.

In the polyamide-imide resin, the content of the structural unit represented by formula (2) is preferably 0.1 mol or more, more preferably 0.5 mol or more, further preferably 1.0 mol or more, particularly preferably 1.5 mol or more, preferably 6.0 mol or less, more preferably 5.0 mol or less, and further preferably 4.5 mol or less, relative to 1 mol of the structural unit represented by formula (1). When the content of the structural unit represented by formula (2) is not less than the above lower limit, the curl resistance and the elastic modulus of the optical film are easily improved. When the content of the structural unit represented by formula (2) is not more than the upper limit, thickening due to hydrogen bonds between amide bonds in formula (2) is easily suppressed, and the processability of the optical film is easily improved.

In a preferred embodiment of the present invention, the polyimide-based resin and/or the polyamide-based resin contained in the optical film may contain a halogen atom such as a fluorine atom which can be introduced, for example, through the above-mentioned fluorine-containing substituent or the like. When the polyimide-based resin and/or the polyamide-based resin contains a halogen atom, the elastic modulus of the optical film is easily increased, and the YI value is easily decreased. When the elastic modulus of the optical film is high, the occurrence of scratches, wrinkles, and the like is easily suppressed. In addition, when the YI value of the optical film is low, the transparency and visibility of the film are easily improved. The halogen atom is preferably a fluorine atom. Examples of the preferable fluorine-containing substituent for containing a fluorine atom in the polyimide resin include a fluorine group and a trifluoromethyl group.

The content of the halogen atom in the polyimide-based resin and the polyamide-based resin is preferably 1 to 40% by mass, more preferably 5 to 40% by mass, and still more preferably 5 to 30% by mass, based on the mass of the polyimide-based resin and the polyamide-based resin. When the content of the halogen atom is not less than the above lower limit, the elastic modulus of the optical film is further improved, the water absorption is reduced, the YI value is further reduced, and the transparency and the visibility are further improved. When the content of the halogen atom is not more than the above upper limit, the synthesis becomes easy.

The imidization ratio of the polyimide-based resin and the polyamideimide resin is preferably 90% or more, more preferably 93% or more, and further preferably 96% or more. The imidization ratio is preferably not less than the above-described lower limit from the viewpoint of easily improving the optical properties of the optical film. The upper limit of the imidization rate is 100% or less. The imidization ratio indicates a ratio of a molar amount of imide bonds in the polyimide-based resin to a value 2 times a molar amount of structural units derived from a tetracarboxylic acid compound in the polyimide-based resin. When the polyimide resin contains a tricarboxylic acid compound, the molar amount of the imide bond in the polyimide resin is represented by the ratio of a value 2 times the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide resin to the total molar amount of the structural unit derived from the tricarboxylic acid compound. The imidization ratio can be determined by an IR method, an NMR method or the like.

As the polyimide-based resin and the polyamide-based resin, commercially available products can be used. Examples of commercially available polyimide resins include Neopulim (registered trademark) manufactured by Mitsubishi gas chemical corporation, KPI-MX300F manufactured by the riverside industries, and the like.

In the present invention, the optical film may contain a polyamide-based resin. The polyamide resin according to the present embodiment is a polymer mainly composed of a repeating structural unit represented by formula (2). Preferred examples and specific examples of Z in formula (2) in the polyamide resin are the same as preferred examples and specific examples of Z in the polyimide resin. The polyamide resin may contain 2 or more kinds of repeating structural units represented by formula (2) having different Z.

(method for producing resin)

The polyimide resin and the polyimide precursor resin can be produced, for example, from tetracarboxylic acid compounds and diamine compounds as main raw materials, the polyamideimide resin and the polyamideimide precursor resin can be produced, for example, from tetracarboxylic acid compounds, dicarboxylic acid compounds and diamine compounds as main raw materials, and the polyamide resin can be produced, for example, from diamine compounds and dicarboxylic acid compounds as main raw materials. Here, the dicarboxylic acid compound preferably contains at least a compound represented by the formula (3 ").

[ chemical formula 17]

[ formula (3) ], R¹～R⁸Independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, R¹～R⁸The hydrogen atoms contained in (a) may be substituted independently of each other by halogen atoms,

a represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-, -S-, -CO-or-N (R)⁹)-，

R⁹A 1-valent hydrocarbon group having 1 to 12 carbon atoms which is a hydrogen atom or a halogen atom-substituted hydrocarbon group,

m is an integer of 0 to 4,

R³¹and R³²Independently of one another, represents hydroxy or methoxyEthoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group or chlorine atom.]

In a preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by the formula (3 ") wherein m is 0. As the dicarboxylic acid compound, it is more preferable to use a compound represented by the formula (3 ') in which A is an oxygen atom in addition to the compound represented by the formula (3') in which m is 0. In another preferred embodiment, the dicarboxylic acid compound is R³¹And R³²A compound represented by the formula (3') which is a chlorine atom. In addition, a diisocyanate compound may be used instead of the diamine compound.

Examples of the diamine compound that can be used for producing the resin include aliphatic diamines, aromatic diamines, and mixtures thereof. In this embodiment, the "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and may include an aliphatic group or another substituent in a part of the structure. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but are not limited thereto. Among these, benzene rings are preferred. The "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may contain an aromatic ring or other substituent in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as 1, 6-hexamethylenediamine, and cyclic aliphatic diamines such as 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, norbornanediamine, and 4, 4' -diaminodicyclohexylmethane. These can be used alone or in combination of 2 or more.

Examples of the aromatic diamine include aromatic diamines having 1 aromatic ring such as p-phenylenediamine, m-phenylenediamine, 2, 4-tolylenediamine, m-xylylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene and 2, 6-diaminonaphthalene, 4 ' -diaminodiphenylmethane, 4 ' -diaminodiphenylpropane, 4 ' -diaminodiphenyl ether, 3 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, etc., 4 ' -diaminodiphenyl methane, 4 ' -diaminodiphenyl propane, 4 ' -diaminodiphenyl ether, 3,4 ' -diaminodiphenyl ether, 4-diaminodiphenyl sulfone, 3 ' -diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-amino-phenoxy) benzene, bis (4-phenylene) sulfone, bis (4-phenylene) benzene, bis (4-phenylene) benzene, bis (bis) benzene) sulfone, bis (4-phenylene) benzene, bis (4-phenylene) benzene, bis (p) benzene, bis (4-phenylene) benzene, bis (p-phenylene) benzene, bis (2, bis (p-phenylene) benzene, 2, bis (p-phenylene) benzene, 2, bis (p-phenylene) benzene, bis (p-phenylene) benzene, 2, bis (bis) benzene, 2, bis (p) benzene, 2, bis (p-phenylene) benzene, Bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 ' -dimethylbenzidine, 2 ' -bis (trifluoromethyl) -4,4 ' -diaminobiphenyl (sometimes referred to as TFMB), aromatic diamines having 2 or more aromatic rings, such as 4, 4' -bis (4-aminophenoxy) biphenyl, 9-bis (4-aminophenyl) fluorene, 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-chlorophenyl) fluorene, and 9, 9-bis (4-amino-3-fluorophenyl) fluorene. These can be used alone or in combination of 2 or more.

The aromatic diamine is preferably 4,4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether, 3' -diaminodiphenyl ether, 4 '-diaminodiphenyl sulfone, 3' -diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, TFMB, 4' -bis (4-aminophenoxy) biphenyl, more preferred are 4,4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether, 4' -diaminodiphenylsulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, TFMB, and 4, 4' -bis (4-aminophenoxy) biphenyl. These can be used alone or in combination of 2 or more.

Among the diamine compounds, 1 or more selected from the group consisting of aromatic diamines having a biphenyl structure are preferably used from the viewpoints of high elastic modulus, high transparency, high flexibility, high bending resistance, and low coloring of the optical film. More preferably, at least 1 selected from the group consisting of 2,2 ' -dimethylbenzidine, TFMB, 4 ' -bis (4-aminophenoxy) biphenyl, and 4,4 ' -diaminodiphenyl ether is used, and still more preferably, TFMB is used.

Examples of the tetracarboxylic acid compound that can be used for producing the resin include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of 2 or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound, in addition to the dianhydride.

Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides. Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4,4 '-oxydiphthalic dianhydride, 3, 3', 4,4 '-benzophenonetetracarboxylic acid dianhydride, 2', 3,3 '-benzophenonetetracarboxylic acid dianhydride, 3, 3', 4,4 '-biphenyltetracarboxylic acid dianhydride (sometimes referred to as BPDA), 2', 3,3 '-biphenyltetracarboxylic acid dianhydride, 3, 3', 4,4 '-diphenylsulfonetetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic acid dianhydride (4,4 ' - (hexafluoroisopropylidene) dicarboxylic dianhydride, which is sometimes referred to as 6FDA), 1, 2-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 2-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4 ' - (p-phenylenedioxy) diphthalic dianhydride, 4 ' - (m-phenylenedioxy) diphthalic dianhydride. Examples of the monocyclic aromatic tetracarboxylic acid dianhydride include 1,2,4, 5-benzenetetracarboxylic acid dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic acid dianhydride include 2,3,6, 7-naphthalenetetracarboxylic acid dianhydride.

Of these, preferred are 4,4 ' -oxydiphthalic dianhydride, 3,3 ', 4,4 ' -benzophenonetetracarboxylic dianhydride, 2 ', 3,3 ' -benzophenonetetracarboxylic dianhydride, BPDA, 2 ', 3,3 ' -biphenyltetracarboxylic dianhydride, 3,3 ', 4,4 ' -diphenylsulfonetetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 6FDA, 1, 2-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 2-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4 '- (p-phenylenedioxy) diphthalic dianhydride and 4, 4' - (m-phenylenedioxy) diphthalic dianhydride, and more preferably 4,4 '-oxydiphthalic dianhydride, BPDA, 2', 3,3 '-biphenyltetracarboxylic dianhydride, 6FDA, bis (3, 4-dicarboxyphenyl) methane dianhydride and 4, 4' - (p-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of 2 or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include cycloalkanetetracarboxylic dianhydrides such as 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride and 1,2,3, 4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, bicyclohexane-3, 3 ', 4, 4' -tetracarboxylic dianhydride, and positional isomers thereof. These can be used alone or in combination of 2 or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3, 4-butanetetracarboxylic acid dianhydride, and 1,2,3, 4-pentanedicarboxylic acid dianhydride, and these can be used alone or in combination of 2 or more. In addition, cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride can be used in combination.

Among the tetracarboxylic dianhydrides, from the viewpoint of high curl resistance, high elastic modulus, high surface hardness, high transparency, high flexibility, high bending resistance, and low coloring property of the optical film, 4,4 ' -oxydiphthalic dianhydride, 3,3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride, BPDA, 2 ', 3,3 ' -biphenyl tetracarboxylic dianhydride, 3,3 ', 4,4 ' -diphenylsulfone tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 6FDA, and a mixture thereof are preferable, BPDA and 6FDA, and a mixture thereof are more preferable, and 6FDA and BPDA are further more preferable.

As the dicarboxylic acid compound that can be used for producing the resin, terephthalic acid, isophthalic acid, 4' -oxybis benzoic acid, or an acid chloride compound thereof is preferably used. Other dicarboxylic acid compounds may be used in addition to terephthalic acid, isophthalic acid, 4' -oxybis-benzoic acid or their acid chloride compounds. Examples of the other dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and the like, and acid chloride compounds and acid anhydrides thereof, and 2 or more of them may be used in combination. Specific examples thereof include isophthalic acid; naphthalenedicarboxylic acid; 4, 4' -biphenyldicarboxylic acid; 3, 3' -biphenyldicarboxylic acid; a dicarboxylic acid compound of chain hydrocarbon having 8 or less carbon atoms and 2 benzoic acids via a single bond, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene group-linked compounds and their acid chloride compounds. Specifically, 4 '-oxybis (benzoyl chloride), terephthaloyl chloride or isophthaloyl chloride is preferable, and 4, 4' -oxybis (benzoyl chloride) and terephthaloyl chloride are more preferably used in combination.

In addition to the tetracarboxylic acid compound, tetracarboxylic acid and tricarboxylic acid, and their anhydrides and derivatives may be further reacted with the polyimide-based resin within a range that does not impair various physical properties of the optical film.

Examples of the tetracarboxylic acid include water adducts of anhydrides of the above tetracarboxylic acid compounds.

Examples of the tricarboxylic acid compound include an aromatic tricarboxylic acid, an aliphatic tricarboxylic acid, and a similar acid chloride compound or acid anhydride thereof, and 2 or more kinds thereof may be used in combination. Specific examples thereof include anhydrides of 1,2, 4-benzenetricarboxylic acid; anhydrides of 1,3, 5-benzenetricarboxylic acid; 2,3, 6-naphthalene tricarboxylic acid-2, 3-anhydride; phthalic anhydride and benzoic acid through single bond, -O-, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene groups.

In the production of the resin, the amount of the diamine compound, the tetracarboxylic acid compound and/or the dicarboxylic acid compound to be used may be appropriately selected depending on the ratio of each structural unit of the desired polyimide-based resin.

In the production of the resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, and is, for example, 5 to 350 ℃, preferably 20 to 200 ℃, and more preferably 25 to 100 ℃. The reaction time is also not particularly limited, and is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be carried out in an inert atmosphere or under reduced pressure. In a preferred embodiment, the reaction is carried out under normal pressure and/or in an inert gas atmosphere while stirring. The reaction is preferably carried out in a solvent inactive to the reaction. The solvent is not particularly limited as long as it does not affect the reaction, and examples thereof include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone (hereinafter, sometimes referred to as GBL), γ -valerolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N, N-dimethylacetamide (hereinafter sometimes referred to as DMAc) and N, N-dimethylformamide (hereinafter sometimes referred to as DMF); sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; and combinations thereof (mixed solvents). Among these, an amide solvent can be suitably used from the viewpoint of solubility.

In the imidization step in the production of the polyimide-based resin, imidization may be performed in the presence of an imidization catalyst. As imidization catalystsExamples of the oxidizing agent include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; n-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepino

Alicyclic amines (monocyclic); azabicyclo [2.2.1]Heptane, azabicyclo [3.2.1]Octane, azabicyclo [2.2.2]Octane, and azabicyclo [3.2.2]Alicyclic amines (polycyclic) such as nonane; and aromatic amines such as pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2, 4-dimethylpyridine, 2,4, 6-trimethylpyridine, 3, 4-cyclopentenopyridine, 5,6,7, 8-tetrahydroisoquinoline, and isoquinoline. In addition, from the viewpoint of facilitating the imidization reaction, it is preferable to use not only the imidization catalyst but also an acid anhydride. The acid anhydride includes a conventional acid anhydride used in the imidization reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic acid.

The polyimide-based resin and the polyamide-based resin can be separated by separation and purification by a conventional method, for example, separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination thereof, and in a preferred embodiment, the separation can be carried out by adding a large amount of an alcohol such as methanol to a reaction solution containing a transparent polyamide-imide resin, precipitating the resin, concentrating, filtering, drying, or the like.

(optical film)

In the present invention, the content of the polyimide-based resin and/or the polyamide-based resin in the resin composition constituting the optical film is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, particularly preferably 70% by mass or more, and may be 100% by mass, relative to the solid content of the resin composition. When the content of the polyimide-based resin and/or the polyamide-based resin is not less than the lower limit, the optical film has good flexibility. The solid content means the total amount of components obtained by removing the solvent from the resin composition.

In the present invention, the resin composition for forming an optical film may further contain an inorganic material such as inorganic particles in addition to the polyimide-based resin and/or the polyamide-based resin. Examples of the inorganic material include inorganic particles such as silica particles, titanium particles, aluminum hydroxide, zirconia particles, and barium titanate particles, and silicon compounds such as 4-stage alkoxysilanes such as tetraethylorthosilicate. From the viewpoint of the stability of the varnish and the dispersibility of the inorganic material, silica particles, aluminum hydroxide particles and zirconia particles are preferable, and silica particles are more preferable.

The average primary particle diameter of the inorganic material particles is preferably 1 to 100nm, more preferably 5 to 70nm, still more preferably 10 to 50nm, and particularly preferably 10 to 30 nm. When the average primary particle diameter of the silica particles is within the above range, the transparency tends to be improved, and the handling tends to be facilitated because the cohesive force of the silica particles is weak.

In the present invention, the silica particles may be silica sol obtained by dispersing silica particles in an organic solvent or the like, or may be silica fine particle powder produced by a vapor phase method, and silica sol produced by a liquid phase method is preferable from the viewpoint of easy handling.

The average primary particle diameter of the silica particles in the optical film can be determined by observation with a Transmission Electron Microscope (TEM). The average primary particle size of the silica particles before forming the optical film can be determined by the BET method, and the particle size distribution can be determined by a commercially available laser diffraction particle size distribution meter.

In the present invention, when the resin composition contains an inorganic material, the content thereof is preferably 0.001 mass% or more and 90 mass% or less, more preferably 10 mass% or more and 60 mass% or less, and further preferably 15 mass% or more and 40 mass% or less, with respect to the solid content of the resin composition. When the content of the inorganic material in the resin composition is within the above range, the optical film tends to be easily transparent and mechanically strong at the same time. The solid content means the total amount of components obtained by removing the solvent from the resin composition.

The resin composition constituting the optical film may further contain other components in addition to the components described above. Examples of the other components include an ultraviolet absorber, an antioxidant, a mold release agent, a light stabilizer, a bluing agent, a flame retardant, a lubricant, and a leveling agent.

The ultraviolet absorber can be appropriately selected from those generally used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400nm or less. Examples of the ultraviolet absorber include at least 1 compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. The ultraviolet absorber may be used alone or in combination of two or more. Since the optical film contains the ultraviolet absorber, deterioration of the resin can be suppressed, and thus, visibility can be improved when the obtained optical film is applied to an image display device or the like. In the present specification, the term "related compound" refers to a derivative of a compound following the "related compound". For example, the "benzophenone-based compound" refers to a compound having benzophenone as a matrix skeleton and a substituent bonded to benzophenone.

When the optical film contains the ultraviolet absorber, the content of the ultraviolet absorber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 3 parts by mass or more, preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 6 parts by mass or less, relative to 100 parts by mass of the optical film. The preferable content varies depending on the ultraviolet absorber used, but when the content of the ultraviolet absorber is adjusted so that the light transmittance at 400nm becomes about 20 to 60%, not only the light resistance of the optical film can be improved, but also the transparency can be easily improved.

In the present invention, when the resin composition contains a resin component such as a polyimide-based resin and other components other than an inorganic material and an ultraviolet absorber, the content of the other components is preferably 0.001% by mass or more and 20% by mass or less, and more preferably 0.01% by mass or more and 10% by mass or less, based on the total mass of the optical film.

In the present invention, the optical film can be produced, for example, from a resin varnish prepared by adding a solvent to a resin composition containing a polyimide-based resin and/or a polyamide-based resin obtained by selecting and reacting the tetracarboxylic acid compound, the diamine, and the other raw materials, and if necessary, an inorganic material, and other components, and mixing and stirring the mixture. In the resin composition, a solution of a commercially available polyimide resin or the like or a solution of a commercially available solid polyimide resin or the like may be used in place of the reaction solution of the polyimide resin or the like.

As the solvent used for preparing the resin varnish, a solvent capable of dissolving or dispersing a resin component such as a polyimide-based resin can be appropriately selected. The boiling point of the organic solvent is preferably 120 to 300 ℃, more preferably 120 to 270 ℃, even more preferably 120 to 250 ℃, and even more preferably 120 to 230 ℃ from the viewpoint of the solubility, coatability, drying properties, and the like of the resin component. Specific examples of such organic solvents include amide solvents such as DMF, DMAc, and N-methylpyrrolidone; lactone solvents such as GBL and gamma valerolactone; ketone solvents such as cyclohexanone, cyclopentanone, and methyl ethyl ketone; acetate solvents such as butyl acetate and amyl acetate; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane, and carbonate solvents such as ethylene carbonate and propylene carbonate. Among them, from the viewpoint of excellent solubility in the polyimide-based resin and the polyamide-based resin, a solvent selected from the group consisting of DMAc (boiling point: 165 ℃ C.), GBL (boiling point: 204 ℃ C.), N-methylpyrrolidone (boiling point: 202 ℃ C.), butyl acetate (boiling point: 126 ℃ C.), cyclopentanone (boiling point: 131 ℃ C.) and amyl acetate (boiling point: 149 ℃ C.) is preferable. The solvent may be used alone in 1 kind, or may be used in combination with 2 or more kinds. When 2 or more solvents are used, the kind of the solvent is preferably selected so that the boiling point of the solvent having the highest boiling point among the solvents used falls within the above range.

The amount of the solvent is not particularly limited, and may be selected so as to have a viscosity at which the resin varnish can be handled, and for example, is preferably 50 to 95 parts by mass, more preferably 70 to 95 parts by mass, and still more preferably 80 to 95 parts by mass, based on 100 parts by mass of the solid components of the resin composition.

The thickness of the optical film may be determined as appropriate depending on the application of the optical film, and is usually 10 to 500. mu.m, preferably 15 to 200. mu.m, and more preferably 20 to 130. mu.m. When the thickness of the optical film is within the above range, the optical film tends to have good bendability and curl resistance.

< cured resin layer >

The laminated film of the present invention has an optical film and a cured resin layer laminated on one surface of the optical film. The cured resin layer may be provided on the optical film, for example, by: the resin is cured by polymerization, crosslinking, and curing reaction by irradiating the cured resin composition applied on the optical film with active energy rays. In the present invention, the cured resin layer is preferably a layer having a function, and the "function" in the present specification means a function to be imparted to the optical film, and more specifically, a hard coat function, an antistatic function, an antiglare function, a low reflection function, an antireflection function, an antifouling function, a gas barrier function, an undercoating (primer) function, an electromagnetic wave shielding function, an undercoating (undercoat) function, an ultraviolet absorbing function, an adhesive function, a hue adjusting function, and the like, but is not limited thereto. In the present specification, the term "cured" means: not only does the polymerization, crosslinking, and curing reaction proceed, but also the resin layer does not simply peel off from the optical film in order to maintain the function imparted to the optical film. The resin layer having a function (also referred to as a functional layer) may have 1 kind of function, or may have 2 or more kinds of functions. From the viewpoint of ease of use as a front panel of a flexible display device, it is preferable that at least 1 of the functional layers is a layer having at least 1 function selected from the group consisting of a hard coat function, an antistatic function, an antiglare function, a low reflection function, an antireflection function, and an antifouling function. The functional layer may have a plurality of functions in 1 layer, or 2 or more layers having each function may be stacked. When 2 or more layers are stacked, the order of stacking can be set as appropriate according to the function. These layers may be laminated on one or both sides of the optical film. When the layers are laminated on both surfaces, the thickness, function, and order of lamination of the layers laminated on each surface may be the same or different. From the viewpoint of easily preventing curling of the laminated film, the functional layer is preferably 5 layers or less, more preferably 3 layers or less, further preferably 2 layers or less, and particularly preferably 1 layer.

The thickness of the functional layer may be appropriately set according to the intended function, and is preferably 30 μm or less, more preferably 20 μm or less, further preferably 1 μm or more and 10 μm or less, further preferably 1 μm or more and 8 μm or less, and particularly preferably 2 μm or more and 7 μm or less, from the viewpoints of easy prevention of curling of the laminated film, light weight, and easy improvement of optical homogeneity. Here, the thickness means the thickness of all layers when 2 or more functional layers are stacked. In the present invention, the thickness of the functional layer can be calculated from the difference in thickness from the optical film, for example, using a contact digital thickness meter (digital indicator).

When the thickness of the optical film is T1 and the thickness of the functional layer is T2, T1/T2 is preferably 1 to 40, more preferably 1.5 to 30, still more preferably 2 to 20, and particularly preferably 3 to 10. When T1/T2 is within the above range, the balance between the optical film and the functional layer is obtained, and curling is less likely to occur.

The optical film and the functional layer are preferably sufficiently closely adhered. The adhesion can be evaluated by, for example, a cross hatch test (cross cut test) according to JIS K5600-5-6, specifically, a 10 × 10 checkered flaw was cut at 2mm intervals, Cellotape (registered trademark, manufactured by Nichiban co., ltd.) was attached, the Cellotape was peeled off in a direction of 60 ° with respect to the surface, and then the number of remaining checkerboards was counted. In this case, the larger the number of remaining checkerboards, the higher the adhesion, and the number thereof is preferably 100.

(hard coating function)

The hard coat function is a function of protecting the optical film by imparting scratch resistance, chemical resistance, and the like to the surface of the optical film. In the laminated film of the present invention, the functional layer may be a layer having a hard coat function, for example, a hard coat layer. As the hard coat layer, known hard coat layers can be suitably used, and examples thereof include known hard coat layers such as acrylic, epoxy, urethane, benzyl chloride, vinyl, and the like. Among these, acrylic, urethane, and a hard coat layer of a combination thereof are preferable from the viewpoint of suppressing a decrease in visibility in the wide angle direction of the laminated film and improving the bending resistance. For example, the hard coat layer may be a cured product of a composition containing an active energy ray-curable compound. The active energy ray-curable compound is a compound having a property of being cured by irradiation with an active energy ray such as an electron beam or ultraviolet ray. Examples of such an active energy ray-curable compound include an electron beam-curable compound which is cured by irradiation with an electron beam, and an ultraviolet-curable compound which is cured by irradiation with ultraviolet light. These compounds are the same compounds as the main components of the hard coat agent used for forming a normal hard coat layer, and examples thereof include (meth) acrylic resins. Among the (meth) acrylic resins, a resin containing a polyfunctional (meth) acrylate compound as a main component is preferable. In the present specification, the term (meth) acrylic-means propylene-and/or methacrylic-and the term (meth) acrylate means acrylate and/or methacrylate.

The polyfunctional (meth) acrylate compound is a compound having at least 2 acryloyloxy groups and/or methacryloyloxy groups in the molecule, and specific examples thereof include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, and mixtures thereof, Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tris ((meth) acryloyloxyethyl) isocyanurate, phosphazene acrylate compound or phosphazene methacrylate compound in which a (meth) acryloyloxy group is introduced into a phosphazene ring of the phosphazene compound, urethane (meth) acrylate compounds obtained by the reaction of polyisocyanates having at least 2 isocyanate groups in the molecule with polyol compounds having at least 1 (meth) acryloyloxy group and hydroxyl group, polyester (meth) acrylate compounds obtained by the reaction of carboxylic acid halides having at least 2 functional groups in the molecule with polyol compounds having at least 1 (meth) acryloyloxy group and hydroxyl group, and oligomers such as dimers, trimers, and the like of the above compounds.

These compounds may be used alone or in combination of 2 or more. In addition to the above-mentioned polyfunctional (meth) acrylate compound, at least 1 type of monofunctional (meth) acrylate may be used. Examples of the monofunctional (meth) acrylate include hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and glycidyl (meth) acrylate. These compounds may be used alone or in combination of 2 or more. The content of the monofunctional (meth) acrylate compound is preferably 10 mass% or less with respect to the solid content of the compound contained in the functional layer forming composition, for example, the hard coat layer coating material. In the present specification, the solid component means all components except for the solvent contained in the curable composition.

In the functional layer, for example, a polymerizable oligomer may be added for the purpose of adjusting hardness. Examples of such oligomers include macromonomers such as terminal (meth) acrylate polymethyl methacrylate, terminal styrene-based poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylonitrile-styrene copolymer, and terminal (meth) acrylate styrene-methyl (meth) acrylate copolymer. When the polymerizable oligomer is added, the content thereof is preferably 5 to 50% by mass relative to the solid content of the functional layer forming composition.

The active energy ray-curable compound may be used in the form of a solution mixed with a solvent. The active energy ray-curable compound or a solution thereof may be a product commercially available as a hard coat agent. Specific examples of commercially available hard coating agents include NK HardM101 (manufactured by Nizhou chemical Co., Ltd., urethane acrylate compound), NK EsterA-TMM-3L (manufactured by Nizhou chemical Co., Ltd., tetramethylolmethane triacrylate), NKEster A-9530 (manufactured by Nizhou chemical Co., Ltd., dipentaerythritol hexaacrylate), KAYARAD (registered trademark) DPCA series (manufactured by Nippon Kagaku K.K., derivatives of dipentaerythritol hexaacrylate compound), ARONIX (registered trademark) M-8560 (manufactured by Tokya Synthesis Co., Ltd., polyester acrylate compound), NEW FRONTER (registered trademark) TEICA (manufactured by first Industrial pharmaceutical Co., Ltd., tris (acryloyloxyethyl) isocyanurate), PPZ (manufactured by Kyowa chemical Co., Ltd., phosphazene methacrylate compound), and the like.

As a method for laminating a hard coat layer on an optical film, for example, a composition for forming a hard coat layer containing an active energy ray-curable compound or an active energy ray-curable resin may be applied to the surface of an optical film and irradiated with an active energy ray. Such a composition can be obtained by mixing an active energy ray-curable compound with additives and the like as needed. A cured product of the composition for forming a hard coat layer constitutes a hard coat layer.

The composition for forming a hard coat layer preferably contains a solvent, and in the composition for forming a hard coat layer, the active energy ray-curable compound is preferably diluted with the solvent. In this case, the composition can be produced by mixing the active energy ray-curable compound with various additives for imparting surface smoothness or the like, for example, silicone oil or the like, and then diluting the obtained mixture with a solvent, or can be produced by mixing the active energy ray-curable compound with additives diluted with a solvent in advance, or can be produced by mixing the active energy ray-curable compound diluted with a solvent in advance with additives diluted with a solvent in advance. The mixed composition may be further stirred.

The composition for forming a hard coat layer also preferably contains an appropriate solvent from the viewpoint of facilitating the application. The solvent can be suitably selected from aliphatic hydrocarbons such as hexane and octane, aromatic hydrocarbons such as toluene and xylene, alcohols such as ethanol, 1-propanol, isopropanol and 1-butanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, cellosolves, and the like. These organic solvents may be used in combination of plural kinds as required. The boiling point of the solvent is preferably in the range of 70 to 200 ℃ from the viewpoint of facilitating the evaporation of the organic solvent by heating after the application of the hard coat layer-forming composition. The kind and amount of the solvent to be used can be appropriately selected depending on the kind and amount of the active energy ray-curable compound to be used, the material and shape of the substrate, for example, an optical film, the coating method, the thickness of the target hard coat layer, and the like.

The heating temperature for drying the coated hard coat layer-forming composition is preferably ± 30 ℃, more preferably ± 20 ℃ with respect to the boiling point of the solvent contained in the composition. When the drying temperature of the composition for forming a hard coat layer is within the above range, the following tendency is present: the solvent is less likely to remain in the obtained hard coat layer, and the adhesion is less likely to decrease.

The solid content of the composition for forming a hard coat layer is preferably 5 to 60% by mass, more preferably 10 to 55% by mass, even more preferably 20 to 50% by mass, and particularly preferably 25 to 50% by mass. When the solid content is within the above range, the following tendency is present: the coating thickness was not too large, the effect of preventing curling was good, and the surface smoothness of the obtained hard coat layer was good.

The hard coat layer-forming composition may contain a polymerization initiator. When ultraviolet rays or visible rays are used as the active energy rays, a photopolymerization initiator is usually used as the polymerization initiator.

Examples of the photopolymerization initiator include acetophenone, acetophenone benzyl ketal, anthraquinone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, carbazole, xanthone, 4-chlorobenzophenone, 4 '-diaminobenzophenone, 1-dimethoxydeoxybenzoin, 3' -dimethyl-4-methoxybenzophenone, thioxanthone, 2-dimethoxy-2-phenylacetophenone, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, and mixtures thereof, Triphenylamine, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene, benzaldehyde, benzoin ethyl ether, benzoin isopropyl ether, benzophenone, Michler's ketone, 3-methylacetophenone, 3', 4,4 '-tetra-tert-butylperoxycarbonylbenzophenone (sometimes referred to as BTTB), 2- (dimethylamino) -1- [4- (morpholino) phenyl ] -2-phenylmethyl) -1-butanone, 4-benzoyl-4' -methyl diphenyl sulfide, benzil, and the like. In addition, a photopolymerization initiator may be used in combination with a pigment sensitizer. Examples of the dye sensitizer include xanthene, thioxanthene, coumarin, and ketocoumarine (ketocoumarins). Examples of the combination of the photopolymerization initiator and the dye sensitizer include a combination of BTTB and xanthene, a combination of BTTB and thioxanthene, a combination of BTTB and coumarin, and a combination of BTTB and coumarin.

When the photopolymerization initiator is used, the amount of the photopolymerization initiator used is preferably 0.1 part by mass or more per 100 parts by mass of the active energy ray-curable compound. When the amount is within the above range, a sufficient curing rate tends to be easily obtained. The amount of the photopolymerization initiator used is preferably 10 parts by mass or less per 100 parts by mass of the active energy ray-curable compound.

The composition for forming a hard coat layer may contain an antistatic agent in addition to the active energy ray-curable compound. By adding an antistatic agent to the composition, an antistatic function can be imparted to the hard coat layer. Examples of the antistatic agent include a surfactant, a conductive polymer, conductive particles, an alkali metal salt and/or an organic cation-anion salt. These antistatic agents may be used in a single amount of 1 kind or in a mixture of 2 or more kinds.

Examples of the surfactant include hydrocarbon surfactants, fluorine surfactants, and polysiloxane surfactants.

Examples of the conductive polymer include polyaniline, polypyrrole, polyacetylene, and polythiophene.

Examples of the conductive particles include particles of indium-tin composite oxide (ITO), antimony-doped tin oxide, and the like.

Examples of the alkali metal salt include organic and inorganic salts of an alkali metal. Examples of the alkali metal ion constituting the cation portion of the alkali metal salt include lithium, sodium, and potassium ions. Among these alkali metal ions, lithium ions are preferable.

The anion portion of the alkali metal salt may be composed of an organic substance or an inorganic substance. As the anion portion constituting the organic salt, for example, CH can be used₃COO-、CF₃COO-、CH₃SO₃-、CF₃SO₃-、(CF₃SO₂)₃C-、C₄F₉SO₃-、C₃F₇COO-、(CF₃SO₂)(CF₃CO)N-、(FSO₂)₂N-、-O₃S(CF₂)₃SO₃-、CO₃ ²-, formula (A1) to formula (A4), (A1): (C)_nF_2n+1SO₂)₂N- (N represents an integer of 1 to 10), (A2): CF (compact flash)₂(C_mF_2mSO₂)₂N- (m represents an integer of 1 to 10), (A3): -O₃S(CF₂)_lSO₃- (l represents an integer of 1 to 10), (A4): (C)_pF_2p+1SO₂)N-(C_qF_2q+1SO₂) (wherein, pAnd q independently represents an integer of 1 to 10). Among them, an anion portion containing a fluorine atom is preferably used because an ionic compound having good ion dissociation property can be obtained. As the anion moiety constituting the inorganic salt, Cl-, Br-, I-, AlCl-can be used₄-、Al₂Cl₇-、BF₄-、PF₆-、ClO₄-、NO₃-、AsF₆-、SbF₆-、NbF₆-、TaF₆-、(CN)₂N-, etc. As the anion portion, (FSO) is preferable₂)₂N-、(CF₃O₂)₂N-、(C₂F₅SO₂)₂N-, more preferably (FSO)₂)₂N-、(CF₃SO₂)₂N-。

The organic cation-anion salt is an organic salt in which a cation portion is organic and an anion portion is included. The anion portion may be an organic or inorganic substance. An "organic cation-anion salt" can be a substance referred to as an ionic liquid, an ionic solid.

Specific examples of the cation component include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, a cation having a pyrrole skeleton, an imidazolium cation, a tetrahydropyrimidinium cation, a dihydropyrimidinium cation, a pyrazolium cation, a pyrazolinium cation, a tetraalkylammonium cation, a trialkylsulfonium cation, and a tetraalkylphosphonium cation. Examples of the anionic component include the same anionic portion as that of the alkali metal salt. Among them, an anionic component containing a fluorine atom is preferably used because an ionic compound having good ion dissociation property can be obtained.

The composition for forming a hard coat layer may contain, for example, an organic compound containing a bromine atom, a fluorine atom, a sulfur atom, a benzene ring, etc., and, for example, inorganic oxide fine particles such as tin oxide, antimony oxide, titanium oxide, zirconium oxide, zinc oxide, silicon oxide, etc. In this case, the refractive index of the obtained hard coat layer can be adjusted, and optical functions such as a low reflection function and an antireflection function can be provided to the hard coat layer.

The layer containing the active energy ray-curable compound can be formed by applying the composition for forming a hard coat layer containing the active energy ray-curable compound onto an optical film and then drying the composition. The coating can be carried out by a usual method such as a micro-gravure coating method, a roll coating method, a dip coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, or a spray coating method. From the viewpoint of easily improving the optical homogeneity of the laminated film, it is preferable to laminate the composition for forming a hard coat layer by a micro-gravure coating method or a die coating method.

Then, the active energy ray-curable compound applied to the surface of the optical film is cured by irradiation with an active energy ray, whereby a target hard coat layer can be obtained. Examples of the active energy ray include electron beams, ultraviolet rays, visible rays, and the like, and can be appropriately selected according to the type of the active energy ray-curable compound used. The active energy ray may be irradiated in the same manner as in the formation of a general hard coat layer. The intensity of the active energy ray to be irradiated, the irradiation time, and the like can be appropriately selected depending on the kind of the curable compound to be used, the thickness of the layer containing the curable compound, and the like. The active energy ray may be irradiated in an inert gas atmosphere. In order to irradiate the active energy ray in the nitrogen atmosphere, for example, the active energy ray irradiation may be performed in a container closed with an inert gas, and as the inert gas, nitrogen, argon, or the like may be used.

An antireflection layer and a low reflection layer, which will be described later, may be further laminated on the surface of the hard coat layer. In this case, the antireflection layer and the low reflection layer may be laminated on the surface of the hard coat layer in a single layer or a plurality of layers.

(antistatic function)

The antistatic function is a function of preventing the surface of the optical film from being charged. In the laminated film of the present invention, the functional layer may be a layer having an antistatic function, for example, an antistatic layer. As a method for forming an antistatic layer, in addition to a method for adding an antistatic agent to the composition for forming a hard coat layer to impart an antistatic function to the hard coat layer, the following methods may be mentioned: the composition for forming an antistatic layer obtained by diluting an antistatic agent with a solvent or the like is applied to an optical film or a functional layer laminated on the optical film, and dried as necessary, to form a separate film. The antistatic agent may be contained as a structural unit having an antistatic function in a part of a resin constituting the functional layer, for example, a cured product of the active energy ray-curable compound described above, or may be added as an additive to the resin forming the functional layer. When the antistatic agent is added as an additive, the amount of the antistatic agent added is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.1 to 10% by mass, based on the solid content of the functional layer forming composition.

(anti-dazzle function)

The antiglare function is a function of scattering and reflecting light to prevent external light from being reflected. In the laminate film of the present invention, the functional layer may be a layer having an antiglare function, for example, an antiglare layer. As the antiglare layer, known ones can be suitably used. For example, an antiglare function can be provided by forming a layer having a fine uneven shape on the surface thereof by using a resin composition in which 1 or more kinds of light-transmitting fine particles are contained in a light-transmitting resin. More specifically, such an antiglare layer can be formed, for example, by: the optical film is coated with a light-transmitting resin solution in which light-transmitting fine particles as a filler are dispersed, and the thickness of the coating is adjusted so that the light-transmitting fine particles form convex portions on the surface of the antiglare layer. In the present specification, the term "light-transmitting property" means: light is substantially transmitted with or without scattering within the material.

(light-transmitting Fine particles)

Examples of the light-transmitting fine particles include organic fine particles such as (meth) acrylic resins, melamine resins, polyethylene resins, polystyrene resins, polycarbonate resins, vinyl chloride resins, organopolysiloxane resins, and acrylic-styrene copolymers, and inorganic fine particles such as calcium carbonate, silica, alumina, barium carbonate, barium sulfate, titanium oxide, and glass. As the light-transmitting fine particles, 1 kind or 2 or more kinds of fine particles can be used. In order to obtain the desired antiglare property, the kind, particle diameter, refractive index, content, and the like of the light-transmitting fine particles may be appropriately adjusted.

The diameter of the light-transmitting fine particles is preferably 0.5 to 5 μm, more preferably 1 to 4 μm. When the particle diameter of the light-transmitting fine particles is within the above range, a necessary light diffusion effect is easily obtained, and since unevenness is easily formed on the surface of the antiglare layer, a sufficient antiglare effect is easily obtained. Further, the surface shape of the antiglare layer does not become rough, and the haze value tends not to increase greatly.

The difference in refractive index between the light-transmitting fine particles and the light-transmitting resin is preferably 0.02 to 0.2, and more preferably 0.04 to 0.1. When the refractive index difference is within the above range, a sufficient light diffusion effect is easily obtained, and the entire laminated film is less likely to whiten.

The amount of the light-transmitting fine particles added is preferably 3 to 30 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of the light-transmitting resin. When the amount of the additive is within the above range, a sufficient light diffusion effect is easily obtained, and the entire laminated film is less likely to whiten.

When the particle diameter and the amount of the light-transmitting fine particles and/or the refractive index difference between the light-transmitting fine particles and the light-transmitting resin are adjusted to the above ranges, the transmission sharpness is not reduced even in a region with high haze of the antiglare layer, and the surface glare is easily prevented, and the glare is easily prevented while maintaining the high transmission sharpness even in a region with low haze.

(light-transmitting resin)

The light-transmitting resin constituting the antiglare layer is not particularly limited as long as it is a resin having light-transmitting properties, and examples thereof include cured products of thermosetting resins, thermoplastic resins, and metal alkoxide polymers, in addition to cured products of the active energy ray-curable compounds described above. Among them, a cured product of an active energy ray-curable compound is preferable. When an ultraviolet-curable resin or the like is used as the active energy ray-curable compound, a photopolymerization initiator, for example, a radical polymerization initiator may be contained in the coating liquid, and the coating layer may be cured by irradiation with active energy rays, as described above.

Examples of the thermosetting resin include thermosetting polyurethane resins formed from an acrylic polyol (acryl polyol) and an isocyanate prepolymer, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and polysiloxane resins.

Examples of the thermoplastic resin include cellulose derivatives such as acetyl cellulose, nitrocellulose, acetyl butyl cellulose, ethyl cellulose, and methyl cellulose; vinyl resins such as vinyl acetate and copolymers thereof, vinyl chloride and copolymers thereof, vinylidene chloride and copolymers thereof; acetal resins such as polyvinyl formal and polyvinyl butyral; (meth) acrylic resins such as acrylic resins and copolymers thereof, methacrylic resins and copolymers thereof; a polystyrene-based resin; a polyamide resin; a polyester resin; polycarbonate-based resins, and the like.

As the metal alkoxide polymer, a silicon oxide-based matrix using a silicon alkoxide-based material as a raw material, or the like can be used. Specifically, the metal alkoxide polymer may be an inorganic or organic-inorganic composite substrate obtained by dehydrating and condensing a hydrolysate of alkoxysilane such as tetramethoxysilane or tetraethoxysilane.

When a cured product of a thermosetting resin or a metal alkoxide polymer is used as the light-transmitting resin, heating may be required after the coating liquid is applied.

In addition, the refractive index of the ultraviolet curable resin is generally about 1.5, which is about the same as that of glass, but the refractive index of the ultraviolet curable resin used may be lower in comparison with the refractive index of the light-transmissive fine particles. In this case, TiO, which is fine particles having a high refractive index, may be added to the light-transmitting resin to such an extent that the light diffusibility in the antiglare layer can be maintained₂(refractive index: 2.3 to 2.7) and Y₂O₃(refractive index: 1.87) La₂O₃(refractive index: 1.95) ZrO₂(refractive index: 2.05), Al₂O₃(refractive index: 1.63) and the like, and the refractive index of the transparent resin is increased to a preferable range.

The composition for forming an antiglare layer can be produced by dispersing light-transmitting fine particles in a composition containing a light-transmitting resin and a solvent, for example, the composition for forming a hard coat layer described above. The timing and the dispersion method for dispersing the light-transmissive fine particles are not particularly limited.

The composition for forming an antiglare layer can be applied to the surface of an optical film or the surface of a functional layer laminated on the optical film and dried to form an antiglare layer. The coating can be carried out by a common method, for example, a method such as a micro gravure coating method, a roll coating method, a dip coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, or a spray coating method. Then, the ultraviolet curable resin is preferably cured by irradiation with ultraviolet light. The intensity of the ultraviolet ray to be irradiated, the irradiation time, and the like can be appropriately selected depending on the kind of the curable compound to be used, the thickness of the layer containing the curable compound, and the like. The ultraviolet rays may be irradiated in an inert gas atmosphere. In order to irradiate ultraviolet rays in an inert gas atmosphere, for example, active energy ray irradiation may be performed in a container closed with an inert gas, and as the inert gas, nitrogen gas, argon gas, or the like may be used.

As another method of forming the antiglare layer, embossing treatment may be used. In this method, after applying a composition for forming an antiglare layer to an optical film or a functional layer laminated on the optical film, the coating layer is cured as necessary while pressing a mold called an embossing roll having a predetermined surface roughness shape against the coating layer, thereby imparting roughness to the surface of the coating layer. It is also effective to perform a second curing step of irradiating ultraviolet light again from the antiglare layer side for the purpose of further promoting the curing reaction of the antiglare layer after the antiglare layer is peeled off from the embossing roller.

The haze of the anti-dazzle layer is preferably 0.1-50%. The haze of the antiglare layer can be measured by a method according to JIS K7361. The thickness of the antiglare layer can be appropriately adjusted so that the haze of the antiglare layer falls within the above range, for example, and is preferably 2 to 20 μm. When the thickness of the antiglare layer is within the above range, a sufficient antiglare effect is easily obtained, cracking of the antiglare layer is easily prevented, and a decrease in productivity due to curling of the antiglare layer caused by curing shrinkage of the antiglare layer is easily prevented. In general, the thickness of the antiglare layer is preferably 85% or more, more preferably 100% or more, with respect to the weight-average particle diameter of the dispersed light-transmitting fine particles. When the thickness of the antiglare layer is within the above range, the following tendency is present: the haze does not become too large, and the visibility is not easily deteriorated.

The antiglare layer may contain an antistatic agent. By containing an antistatic agent, an antiglare layer having an antistatic function can be obtained. Examples of the antistatic agent include the same antistatic agents as those added to the hard coat layer.

The antiglare layer may have a low reflection layer on its outermost surface, i.e., the concavo-convex surface side. Although a sufficient antiglare function is exhibited even in the absence of the low-reflection layer, the antiglare property can be further improved by providing the low-reflection layer on the outermost surface. As the low reflection layer, a low reflection layer described later can be applied.

(antireflection function and Low reflection function)

The antireflection function and the low reflection function are functions of preventing or reducing reflection of external light. In the multilayer film of the present invention, the functional layer may be a layer having a function of preventing reflection of external light (hereinafter, sometimes referred to as an antireflection layer) or a layer having a function of reducing reflection of external light (hereinafter, sometimes referred to as a low reflection layer). The antireflection layer and the low reflection layer may be a single layer or a plurality of layers.

(anti-reflection layer)

The antireflection layer may be provided with a low refractive index layer. The antireflection layer may have a multilayer structure including a low refractive index layer and a high refractive index layer and/or a medium refractive index layer laminated between the low refractive index layer and the optical film. The hard coat layer described above may be provided between the antireflection layer and the optical film.

The thickness of the anti-reflection layer is preferably 0.01 to 1 μm, and more preferably 0.02 to 0.5. mu.m. Examples of the antireflection layer include: a low refractive index layer having a refractive index smaller than the refractive index of the optical film or functional layer on which the antireflection layer is laminated, for example, a refractive index of 1.3 to 1.45; and a layer in which a low refractive index layer of a thin film made of an inorganic compound and a high refractive index layer of a thin film made of an inorganic compound are alternately laminated in a plurality of layers. Here, the refractive index of the high refractive index layer may be larger than that of the low refractive index layer, and is preferably 1.60 or more.

The material for forming the low refractive index layer is not particularly limited as long as it has a low refractive index. Examples thereof include active energy ray-curable resins, resin materials such as ultraviolet ray-curable acrylic resins, mixed materials in which inorganic fine particles such as colloidal silica are dispersed in a resin, and sol-gel materials using metal alkoxides such as tetraethoxysilane. These materials for forming the low refractive index layer may be polymers after completion of polymerization, or may be monomers or oligomers which become precursors. In addition, the material constituting the antireflection layer preferably contains a fluorine-containing compound in order to impart an antifouling function to the antireflection layer.

The high refractive index layer can be formed by applying a coating solution containing the cured product of the active energy ray-curable resin, the light-transmitting resin such as a metal alkoxide polymer, and the inorganic fine particles and/or the organic fine particles, and then curing the coating layer as necessary. Examples of the inorganic fine particles include zinc oxide, titanium oxide, cerium oxide, aluminum oxide, silane oxide, tantalum oxide, yttrium oxide, ytterbium oxide, zirconium oxide, antimony oxide, Indium Tin Oxide (ITO), and the like. The high refractive index layer containing these inorganic fine particles may also have an antistatic function.

Examples of a method for producing a multilayer film in which transparent thin films of inorganic compounds having different refractive indices, for example, metal oxides, are laminated include: a method of forming a thin film by forming a film of colloidal metal oxide particles by a chemical vapor deposition method, a physical vapor deposition method, or a sol-gel method of a metal compound such as a metal alkoxide, and then performing a post-treatment such as ultraviolet irradiation or plasma treatment described in jp 9-157855 a.

On the other hand, from the viewpoint of facilitating improvement in productivity, it is also preferable to laminate an antireflection layer by coating a thin film in which inorganic particles are dispersed in a matrix. In addition, when an antireflection layer is laminated by applying an antireflection layer-forming composition in which inorganic particles are dispersed in a matrix, an antiglare function can be further provided to the antireflection layer by forming a fine uneven shape on the application surface.

(Low reflection layer)

The low reflection layer is a layer formed of a low refractive index material having a lower refractive index than the optical film to be the base material. The low refractive index layer may be formed using the following method: after applying a coating liquid containing the cured product of the active energy ray-curable resin, the light-transmitting resin such as the metal alkoxide polymer, and the inorganic fine particles, the coating layer is cured as necessary. Specific examples of such a low refractive index material include: lithium fluoride (LiF) and magnesium fluoride (MgF) are added to acrylic resin, epoxy resin and the like₂) Aluminum fluoride (AlF)₃) Cryolite (3 NaF. AlF)₃Or Na₃AlF₆) Inorganic low-reflective materials obtained from fine particles of inorganic materials; fluorine-based or polysiloxane-based organic compounds, thermoplastic resins, thermosetting resins, ultraviolet-curable resins, and other organic low-reflection materials.

(antifouling function)

The antifouling function is a function of preventing fouling, and is a function obtained by imparting water repellency, oil repellency, sweat resistance, antifouling property, fingerprint resistance, and the like to a layer. In the laminated film of the present invention, the functional layer may be a layer having an antifouling function, for example, an antifouling layer. The material for forming the antifouling layer may be an organic compound or an inorganic compound. Examples of the material that imparts high water repellency and oil repellency include fluorine-containing organic compounds and organosilicon compounds. Examples of the fluorine-containing organic compound include fluorocarbons, perfluorosilanes, and polymer compounds thereof. From the viewpoint of easily improving the effect of preventing the adhesion of stains, a material whose contact angle of the surface of the stain-proofing layer with respect to pure water is 90 degrees or more, and further 100 degrees or more is preferable. As a method for forming the antifouling layer, a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, and the like, which are typical examples of evaporation and sputtering, can be used depending on a material to be formed. The average thickness of the antifouling layer is usually about 1 to 50nm, preferably 3 to 35 nm.

(ultraviolet ray absorption function)

In the multilayer film of the present invention, the functional layer may be an ultraviolet absorbing layer having a function of absorbing ultraviolet rays. The ultraviolet absorbing layer may be composed of a main material selected from ultraviolet-curable light-transmitting resins, electron beam-curable light-transmitting resins, and thermosetting light-transmitting resins, and an ultraviolet absorber dispersed in the main material.

(adhesive function)

In the laminated film of the present invention, the functional layer may be an adhesive layer having an adhesive function of adhering the optical film to another member. As a material for forming the adhesive layer, a generally known material can be used. For example, a thermosetting resin composition or a photocurable resin composition can be used. In this case, the thermosetting resin composition or the photocurable resin composition can be polymerized and cured by supplying energy after the polymerization.

The Pressure-Sensitive Adhesive layer may be a layer called a Pressure-Sensitive Adhesive (PSA) that can be attached to an object by pressing. The pressure-sensitive adhesive may be a capsule adhesive as "a substance having adhesiveness at normal temperature and adhering to an adherend by a light pressure" (JIS K6800) or as "an adhesive which contains a specific component in a protective film (microcapsule) and can maintain stability until the film is broken by an appropriate means (pressure, heat, or the like)".

(hue adjusting function)

In the laminated film of the present invention, the functional layer may be a hue adjustment layer having a function of adjusting the laminated film to a target hue. The hue adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, titanium oxide-based calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; organic pigments such as azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, perylene-based compounds, isoindolinone-based compounds, phthalocyanine-based compounds, quinophthalone-based compounds, threne-based compounds, and diketopyrrolopyrrole-based compounds; bulk pigments such as barium sulfate and calcium carbonate; and basic dyes, acid dyes, mordant dyes, and the like.

< protective film >

In the present invention, the "protective film" is a film laminated to temporarily protect the laminated film from damage or deformation caused from the outside, and is not present when the laminated film is actually used for a use. The protective film may be attached to the surface of the cured resin layer without the optical film, and is referred to as a protective film 1. When the multilayer film is wound in a roll form, if there is a problem in winding properties such as blocking, a protective film may be attached to the surface of the optical film free from the cured resin layer in addition to the above. This protective film is referred to as a protective film 2. The protective films 1 and 2 may be the same or different from each other, and hereinafter, when only referred to as a protective film, the two protective films will be described.

The protective film is a film for temporarily protecting the surface of the optical film, and is not particularly limited as long as it is a peelable film capable of protecting the surface of the laminated film. Examples thereof include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; the resin film is preferably selected from the group consisting of polyolefin resin films, polyethylene, polypropylene films and the like, acrylic resin films and the like.

The thickness of the protective film is not particularly limited, but is usually 10 to 250 μm, preferably 10 to 180 μm, and more preferably 20 to 150 μm. When the protective films are bonded to both surfaces of the laminate film, the thicknesses of the protective films on the respective surfaces may be the same or different, and from the viewpoint of suppressing curling of the laminate film during storage or transportation in a high-temperature environment, it is preferable that the relationship Tp1 > Tp2 be satisfied when the thickness of the protective film 1 is Tp1 and the thickness of the protective film 2 is Tp 2. Tp1 is preferably 75 μm or more, more preferably 100 μm or more, and further preferably 120 μm or more. When Tp1 is equal to or greater than the lower limit, moisture is less likely to be removed from the entire laminated film, and therefore, deterioration of the curl can be prevented, and the curl of the laminated film when unwound from the film roll is likely to be reduced. From the viewpoint of the productivity of the film roll, the upper limit of Tp1 is preferably 200 μm or less. Tp1/Tp2 is preferably 1.1 or more and 6 or less, more preferably 1.2 or more and 5 or less, and further preferably 1.3 or more and 4 or less. When Tp1/Tp2 is within the above range, even when the protective films 1 and 2 are also shrunk, the balance of the warpage generated is easily obtained, and the curling is not easily generated.

< roll of film >

In the present invention, a combination of the above-described laminated film having the optical film and the cured resin layer and the protective film 1, or a combination of the protective film 2, the laminated film having the optical film and the cured resin layer, the protective film 1, and the like is wound around the core, and the resultant is referred to as a film roll. The film roll is often stored in a roll form due to space or the like in a continuous production process, and the film roll of the present invention is also one of them. In the present invention, the winding method of the film roll needs to be the order of the optical film, the cured resin layer as the functional layer, and the protective film 1 from the core side of the roll. In the case of the protective film 2, the optical film, the cured resin layer as the functional layer, and the protective film 1 need to be in this order from the core side of the roll. When the film roll is formed in the above-described order, even if the film roll is stored in a high-temperature dry environment, the curl is not generated or is reduced when the film roll is unwound and used. In the present specification, the term "curl" refers to a state in which an end portion of a laminated film is separated from a plane when one surface of the laminated film is placed on the plane as described above. The curl was measured by the method for measuring the curl amount described in examples, and the curl amount was determined. The amount of curling is considered to be larger when the laminate film is placed on a flat surface and the distance from the end portion to the flat surface is larger. From the viewpoint of ease of handling of the film after unwinding, the curl amount is preferably 10mm or less, more preferably 7mm or less, and further preferably 5mm or less.

In the present invention, the cured resin layer, which is a functional layer that is not easily removed by water, among the layers of the laminated film is disposed on the outer side, that is, on the side away from the core, from the viewpoint of reducing the curl of the laminated film due to the severe occurrence of curling of the film roll in a high-temperature environment. Therefore, when the optical film is disposed on the core side, the functional cured resin layer is disposed on the outer side, and the protective film 1 is disposed on the outer side thereof in winding the laminated film, the cured resin layer and the protective film 1, which are functional layers that are not easily removed by water, are located on the outer side in a high-temperature environment, particularly a high-temperature dry environment, and therefore, the curl of the laminated film unwound from the film roll, particularly the curl of the laminated film located on the outermost layer, is reduced.

The water absorption of the laminated film can be measured by the method described in examples in the same manner as the curl. To briefly explain the measurement method, a film having a specific size, for example, a size of 100mm × 100mm, is cut out from a laminated film wound in a roll shape, and the film is sufficiently dried and then the mass is measured in a state where it does not absorb water, and this is taken as the mass W0 of the laminated film before water vapor exposure. Next, the cut laminated film was covered with the opening of a beaker which boiled and released steam, and the mass in the water absorption state after 5 minutes had elapsed was measured, and the measurement result was taken as the mass W1 of the laminated film after water vapor exposure. The water absorption was represented by (W1-W0)/W0X 100. As is clear from this measurement, the water absorption rate represented by the above formula is not the water absorption rate of each layer of the laminated film, but the water absorption rate calculated from the mass of the entire laminated film, and the water absorption rate of the laminated film changes depending on the easiness of water vapor absorption at the surface in contact with vapor at the time of measurement of the laminated film.

Generally, a membrane having a high water absorption rate easily absorbs water, and conversely, easily removes water. Generally, after moisture is removed from the film, the film shrinks, but when the moisture removal from the front and back surfaces of the film is not uniform, the film shrinks to the side having a large moisture removal amount, and the shrinking side becomes the inside and curls. In the high-temperature drying environment, moisture is easily released from the entire film in the thickness direction, and when the film is formed in a roll shape and exposed to the high-temperature drying environment, the deterioration of the curl, that is, the winding of the film to the inside of the roll becomes strong, and particularly, the laminated film near the outermost layer of the film roll sometimes has a very large curl. A film having a low water absorption rate is less likely to release moisture, and is less likely to affect curling of the laminated film due to the storage environment of the film roll. In the film roll of the present invention, the optical film side is wound with the inner side, i.e., the core side, and the cured resin layer side is the outer side, and the protective film 1 is further present on the outer side. When the environment during transport, transportation, or storage of the film roll is a high-temperature dry environment, if the optical film from which moisture is easily removed is located on the outside, the laminated film is strongly wound inside the roll due to moisture removal in the thickness direction of the optical film. In addition, since a solvent used in the production usually remains in the optical film, the solvent is likely to be released even in a high-temperature dry environment, but the curl due to the removal of the solvent can be suppressed also in the film roll of the present invention.

The water absorption of the laminated film when the optical film side is exposed to water vapor is preferably more than 0.75%, more preferably 1.00% or more and 3.00% or less, further preferably 1.05% or more and 2.00% or less, further more preferably 1.10% or more and 1.80% or less, and particularly preferably 1.20% or more and 1.70% or less. When the water absorption rate of the laminated film on the optical film side is within the above range, large warpage of the optical film is less likely to occur when moisture is released from the film, and as a result, curling of the laminated film when the laminated film is unwound from a roll is likely to be reduced. The water absorption of the laminated film when the cured resin layer side is exposed to water vapor is preferably 1.30% or less, more preferably 0.10% or more and 1.20% or less, still more preferably 0.50% or more and 1.10% or less, and particularly preferably 0.75% or more and 1.05% or less. When the water absorption rate of the cured resin layer side of the laminated film is within the above range, moisture desorption from the cured resin layer side is less likely to occur, and moisture desorption as the whole laminated film becomes less likely to occur in a film roll wound so that the cured resin layer side of the laminated film becomes the outer side. In the present invention, the water absorption of the cured resin layer is preferably lower than that of the optical film of the laminated film, and the ratio of the water absorption when the cured resin layer side of the laminated film is exposed to water vapor to the water absorption when the optical film side is exposed to water vapor, in other words, the ratio of the water absorption when the cured resin layer side is exposed to water vapor/the water absorption when the optical film side is exposed to water vapor is preferably 0.25 or more and 0.95 or less, more preferably 0.33 or more and 0.90 or less, still more preferably 0.5 or more and 0.85 or less, and particularly preferably 0.65 or more and 0.83 or less. When the ratio of the water absorption rates of both surfaces of the laminated film is within the above range, the stress applied to the cured resin side of the laminated film and the stress applied to the optical film side are easily cancelled out, and the curl of the laminated film when the laminated film is unwound from the roll is easily reduced.

In the present invention, the optical film constituting the laminated film may contain a solvent in an amount of preferably 0.02% or more and 1.5% or less, more preferably 0.1% or more and 1.2% or less, further preferably 0.3% or more and 1.1% or less, and particularly preferably 0.5% or more and 1.0% or less, with respect to the mass of the optical film. If the content of the solvent is within the above range, the optical film is less likely to be warped greatly when moisture is released from the optical film.

The amount of the solvent in the optical film can be adjusted by drying conditions, annealing conditions, for example, temperature and time in the production of the optical film. The annealing temperature is preferably 120 to 350 ℃, more preferably 150 to 300 ℃, and further preferably 170 to 250 ℃. The time of the annealing treatment can be appropriately set according to the annealing temperature, and for example, when the annealing temperature is 200 ℃, the time of the annealing treatment is preferably more than 20 minutes and 350 minutes or less, more preferably 21 minutes or more and 200 minutes or less, further preferably 22 minutes or more and 150 minutes or less, further preferably 23 minutes or more and 120 minutes or less, and particularly preferably 25 minutes or more and 60 minutes or less. The annealing treatment may be performed in the air, in an inert atmosphere, or under reduced pressure, and is usually performed in the air.

The cured resin layer side of the laminate film of the present invention has a surface hardness of 2B or more, which can be expressed by pencil hardness, for example. The pencil hardness of the multilayer film is preferably B or more and 7H or less, more preferably HB or more and 6H or less, and still more preferably H or more and 5H or less. The pencil hardness may be measured in accordance with JIS K5600-5-4: 1999, the measurement can be carried out by the method described in examples. When the pencil hardness of the laminated film is within the above range, the curling can be prevented from being deteriorated when moisture is removed from the entire thickness direction of the laminated film wound up into a film roll, and the curling amount can be easily reduced.

Examples of the material constituting the core of the film roll include synthetic resins such as polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyester resin, epoxy resin, phenol resin, melamine resin, silicone resin, polyurethane resin, polycarbonate resin, and ABS resin; metals such as aluminum; and fiber reinforced plastics (sometimes abbreviated as FRP) which are composite materials having improved strength by incorporating fibers such as glass fibers in plastics. The winding core is formed in a cylindrical or columnar shape, and has a diameter of, for example, 80 to 170 mm. The diameter of the wound film roll is not particularly limited, and is usually 200 to 800 mm.

The width of the film roll is not particularly limited, and when the width of the optical film is L1 and the width of the cured resin layer is L2, L1 > L2 is preferable, and L2/L1 is preferably 0.80 or more and 0.98 or less, more preferably 0.85 or more and 0.97 or less, and further preferably 0.90 or more and 0.96 or less, from the viewpoint of facilitating improvement of the curl of the laminated film. When L1 is 500mm or more, L1-L2 is preferably 20mm or more and 90mm or less, more preferably 25mm or more and 80mm or less, and still more preferably 30mm or more and 70mm or less.

When the width of the protective film 1 is denoted as L3, L1 > L3 > L2 are preferable, and L1 > L3 prevent the laminate and the laminated film from being contaminated with an adhesive when the protective film 1 has an adhesive layer. L3/L2 is preferably 1.030 or more and 1.070 or less, more preferably 1.035 or more and 1.060 or less, and still more preferably 1.040 or more and 1.060 or less. L3-L2 is 25mm or more and 75mm or less, preferably 20mm or more and 70mm or less, more preferably 35mm or more and 65mm or less, and further preferably 40mm or more and 60mm or less. When L3/L2 and L3-L2 are equal to or more than the lower limit, the protective film 1 located at the outermost layer warps to the opposite side to the winding direction when the protective film 1 shrinks during transportation or transportation, and the warp of the laminated film (optical film + cured resin layer) present inside can be harmonized with the warp, and the curl resistance can be more easily exhibited. When the upper limit values of L3/L2 and L3 to L2 are not more than the upper limit value, warpage generated on the side opposite to the winding direction due to shrinkage of the protective film 1 is easily reduced. The protective film 2 may have the same length as the protective film 1 or a different length from the protective film 1.

< method for producing film roll >

The method for producing a film roll of the present invention having the above-described features is not particularly limited, and for example, the film roll can be produced by a production method including at least the following steps:

(a) a step of forming a coating film by applying a resin varnish containing at least a polyimide resin and/or a polyamide resin and a solvent to a support and drying the resin varnish,

(b) a step of peeling the coating film from the support,

(c) a step of heating the peeled coating film to obtain an optical film, and

(d) a step of laminating a functional cured resin layer on the film,

(e) a step of coating the cured resin layer side of the obtained film with a protective film 1 and, if necessary, with a protective film 2 to obtain a laminated film,

(f) and a step of winding the obtained laminated film so that the optical film is on the core side.

The resin varnish used in the step (a) contains at least a polyimide-based resin and/or a polyamide-based resin and a solvent. Examples of the resin and the solvent that can be contained in the resin varnish include the resins described above as the resins contained in the optical film. The resin varnish may contain additives such as the inorganic materials described above. The solid content concentration of the resin varnish is preferably 1 to 25 mass%, more preferably 5 to 20 mass%.

The resin varnish may be prepared by mixing and stirring the polyimide-based resin and/or the polyamide-based resin, the solvent, and optionally, an additive.

The viscosity of the resin varnish is preferably 5,000 to 60,000cps, more preferably 10,000 to 50,000cps, and further preferably 15,000 to 45,000 cps. When the viscosity of the resin varnish is not lower than the above lower limit, the effect of the present invention is easily obtained, and when it is not higher than the above upper limit, the handling property of the resin varnish is easily improved.

The solid content concentration of the resin varnish is preferably 5 to 25 mass%, more preferably 10 to 23 mass%, and still more preferably 14 to 20 mass%. The solid content concentration of the resin varnish is preferably not lower than the above lower limit from the viewpoint of obtaining a thick film, and preferably not higher than the above upper limit from the viewpoint of ease of handling of the resin varnish.

Examples of the support include a resin substrate, a stainless steel belt, and a glass substrate. As the support, a resin film substrate is preferably used. Examples of the resin film substrate include a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, a Cycloolefin (COP) film, an acrylic film, a polyimide film, and a polyamide-imide film. Among them, a PET film, a COP film, and the like are preferable from the viewpoint of excellent smoothness and heat resistance, and a PET film is more preferable from the viewpoint of adhesion to an optical film and cost.

The thickness of the support is not particularly limited, but is preferably 50 to 250 μm, more preferably 100 to 200 μm, and still more preferably 125 to 200 μm. When the thickness of the support is not more than the above upper limit, the production cost of the optical film is easily suppressed, and therefore, it is preferable. When the thickness of the support is not less than the lower limit, curling of the film which may occur in the step of removing at least a part of the solvent is easily suppressed, and therefore, the thickness is preferable. Here, the thickness of the support can be measured by a contact film thickness meter or the like.

When the resin varnish is applied to the support, the coating to the support can be carried out by a known coating method. Examples of known coating methods include roll coating methods such as wire bar coating, reverse coating, and gravure coating, die coating, comma coating, lip coating, spin coating, screen coating, spray coating, dipping, spraying, and casting.

Next, a coating film of the resin varnish applied to the support is dried, whereby a coating film can be formed. The drying may be performed by removing at least a part of the solvent from the coating film of the resin varnish, and the drying method is not particularly limited. For example, the coating film of the resin varnish applied to the support may be dried by heating.

Next, in the step (b), the dried coating film is peeled off from the support. The peeling method is not particularly limited, and peeling may be performed by moving the coating film with the support fixed, peeling may be performed by moving the support with the coating film fixed, or peeling may be performed by moving both the coating film and the support.

Next, in the step (c), the coating film peeled off in the step (b) is heated to obtain an optical film. In the step (c), the release coating is preferably dried in a state of being stretched in the in-plane direction. The heating temperature during drying is preferably 150 to 300 ℃, more preferably 180 to 250 ℃, and further preferably 180 to 230 ℃. The heating time for drying is preferably 10 to 60 minutes, more preferably 30 to 50 minutes.

The amount of the solvent in the film after the heat treatment is preferably 0.001 to 3% by mass, more preferably 0.001 to 2% by mass, even more preferably 0.001 to 1.5% by mass, and particularly preferably 0.001 to 1.3% by mass, based on the mass of the film. When the amount of the solvent in the film after the heat treatment is within the above range, the appearance of the optical film tends to be good.

Next, in the step (d), a cured resin layer having a function is laminated on one surface of the optical film. Examples of a method for laminating a functional cured resin layer on one surface of a film include: a method of coating a composition for forming a cured resin layer having a function on a film, and if necessary, drying and/or curing the composition to laminate the film; a method of laminating an optical film by bonding a film-like functional cured resin layer to one surface of the optical film. From the viewpoint of facilitating improvement in optical homogeneity of the laminated film, it is preferable to form the laminated film by applying a functional composition for forming a cured resin layer.

In the step (e), the cured resin layer side of the obtained film is covered with a protective film 1, and if necessary, the optical film side is covered with a protective film 2, thereby obtaining a laminated film. The protective film is laminated to protect the surface of the film-like material to be protected as described above. The protective film 2 is formed as needed, and the protective film 1 must be present.

Next, the film roll of the present invention can be obtained by performing a step of winding the laminated film obtained in the step (f) so that the optical film is on the core side.

In the present invention, the order of winding of the film roll is controlled. That is, the film roll of the present invention can eliminate or reduce the curl of the laminated film at the time of unwinding, particularly the curl of the laminated film at the outermost layer portion of the film roll, in the case of storage under a high-temperature dry environment simply by winding the optical film, the cured resin layer, and the protective film 1 in this order from the core side of the roll, and therefore, the curl of the laminated film after unwinding from the film roll can be prevented very easily, and therefore, the technical usefulness thereof is very high. When the protective film 2 is present, the film roll of the present invention is wound in the order of the protective film 2, the optical film, the cured resin layer, and the protective film 1 from the core side of the roll. Generally, the outermost laminated film is discarded because of its large curl and is not suitable for use, but when the film roll of the present invention is used, the discarded portion is lost or reduced, which is very economical, and the effectiveness is high because no unnecessary portion is present.

Examples

The present invention will be described in further detail below with reference to examples. Unless otherwise specified, "%" and "parts" in the examples mean mass% and parts by mass.

First, the measurement method is described in a lump.

< weight average molecular weight >

Gel permeation chromatography assay

(1) Pretreatment method

The sample was dissolved in γ -butyrolactone to prepare a 20 mass% solution, which was diluted to 100 times with N, N-dimethylformamide (sometimes referred to as DMF) eluent, and the solution was filtered through a 0.45 μm membrane filter to obtain a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H.times.2 + SuperAW 2500X 1 (6.0 mm internal diameter, 150mm length, 3 connections)

Eluent: DMF (with addition of 10mmol/L lithium bromide)

Flow rate: 0.6 mL/min

A detector: RI detector

Column temperature: 40 deg.C

Sample introduction amount: 20 μ L

Molecular weight standard: standard polystyrene

< imidization ratio >

Utilization of imidization ratio¹H-NMR was measured and determined in the following manner.

(1) Pretreatment method

The sample was dissolved in deuterated dimethyl sulfoxide (sometimes referred to as DMSO-d)₆) In (3), a2 mass% solution was prepared, and the obtained solution was used as a measurement solution.

(2) Measurement conditions

A measuring device: 400MHz NMR device JNM-ECZ400S/L1 manufactured by JEOL

Standard substance: DMSO-d₆(2.5ppm)

Temperature of the sample: at room temperature

Cumulative number of times: 256 times

Relaxation time: 5 seconds

(3) Method for analyzing imidization rate

In the obtaining of¹In the H-NMR spectrum, benzene protons were observed at 7.0 to 9.0ppm, and the integral ratio of benzene protons A from a structure that did not change before and after imidization was denoted as Int_A. In addition, in 10.5 ~ 11.5ppm observed in the polyimide in the amic acid structure of amide proton, its integral ratio is expressed as Int_B. From these integrated ratios, the imidization ratio was determined by the following equation.

[ mathematical formula 1]

Imidization ratio (%) < 100 × (1-. alpha.Xint)_B/Int_A)

In the above formula, α is the ratio of the number of benzene protons a to 1 amide proton in the case of a polyamic acid having an imidization ratio of 0%.

Viscosity of varnish

According to JIS K8803: 2011, measurement was performed using a Brookfield viscometer DV-II + Pro model E. The measurement temperature was 25 ℃.

< thickness of film >

The thickness of the film was measured at 10 or more points using ID-C112XBS manufactured by Mitutoyo Corporation, and the average value was calculated.

< determination of Pencil hardness >

According to JIS K5600-5-4: 1999, the pencil hardness of the surface of the cured resin layer of the laminated film was measured. The load during the measurement was 750gf, and the measurement speed was 4.5 mm/sec.

< method for measuring residual solvent >

The optical film portion of the laminated film obtained in example 1 was heated from 30 ℃ to 120 ℃ for 5 minutes using TG-DTA (EXSTAR 6000 TG/DTA6300 manufactured by SII corporation), and then heated to 400 ℃ at a heating rate of 5 ℃/minute. The ratio of the mass loss of the optical film from 120 ℃ to 250 ℃ to the mass of the optical film at 120 ℃ was calculated as the content of the solvent contained in the optical film (referred to as the residual solvent amount). The residual solvent amount in the optical film represents a ratio of the solvent contained in the optical film with respect to the mass of the optical film.

The following production examples and abbreviations used in the examples are as follows.

TFMB: 2,2 '-bis (trifluoromethyl) -4, 4' -diaminobiphenyl

6 FDA: 4, 4' - (Hexafluoroisopropylidene) diphthalic dianhydride

TPC: terephthaloyl chloride

And (3) OBBC: 4, 4' -oxybis (benzoyl chloride)

DMAc: n, N-dimethyl acetamide

GBL: gamma-butyrolactone

PET: polyethylene terephthalate

< manufacturing example >

Production example 1: production of Polyamide-imide resin 1

A reaction vessel equipped with a stirring blade in a separable flask and an oil bath were prepared under a nitrogen atmosphere. Into a reaction vessel set in an oil bath, 45 parts of TFMB and 768.55 parts of dmac768.55 parts of dmac were charged. TFMB was dissolved in DMAc while the contents of the reaction vessel were stirred at room temperature. Next, 19.01 parts of 6FDA was further charged into the reaction vessel, and the contents of the reaction vessel were stirred at room temperature for 3 hours. Then, 4.21 parts of OBBC was charged into the reaction vessel, 17.30 parts of TPC was charged into the reaction vessel, and the contents in the reaction vessel were stirred at room temperature for 1 hour. Next, 4.63 parts of 4-methylpyridine and 13.04 parts of acetic anhydride were further charged into the reaction vessel, and the contents of the reaction vessel were stirred at room temperature for 30 minutes. After stirring, the temperature in the vessel was raised to 70 ℃ by using an oil bath, and maintained at 70 ℃ for further 3 hours with stirring, thereby obtaining a reaction solution.

The obtained reaction solution was cooled to room temperature, and put into a large amount of methanol in a linear form to precipitate a precipitate. The resulting precipitate was taken out, immersed in a large amount of methanol for 6 hours, and then washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamideimide resin 1. The weight-average molecular weight of the obtained polyamideimide resin 1 was 400,000, and the imidization rate was 99.0%.

Production example 2: preparation of silica Sol 1

GBL-substituted silica sol was prepared by solvent substitution using, as a raw material, amorphous silica sol (amorphous silica sol) having an average primary particle diameter of 27nm as measured by BET method, which was prepared by sol-gel method. The obtained sol was filtered through a membrane filter having a mesh size of 10 μm to obtain GBL-substituted silica sol 1. The content of silica particles in the obtained GBL-substituted silica sol was 30 mass%.

Production example 3: preparation of resin varnish 1 for optical film

With polyamideimide resin in GBL: the composition ratio of the silica particles was 60: 40, the polyamideimide resin 1 obtained in production example 1 and the GBL-substituted silica sol 1 obtained in production example 2 were mixed. To the resulting mixed solution, 2.0phr of Sumisorb (registered trademark) 250 (molecular weight 389, manufactured by Sumika Chemtex Company, Limited) and 35ppm of Sumiplast (registered trademark) Violet B (registered trademark) with respect to the total mass of the polyamideimide resin and the silica particles were added, and the mixture was stirred until the mixture became uniform, to obtain a resin varnish 1. The solid content of the resin varnish 1 was 9.7% by mass, and the viscosity at 25 ℃ was 39,600 cps.

Production example 4: photocurable resin composition 1

28.4 parts by mass of trimethylolpropane triacrylate (a-TMPT, manufactured by seikoumuramikamuramikamuramikamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamurakamuraka.

Production example 5: production of a film roll 1

The resin varnish 1 obtained in production example 3 was cast on a long PET film substrate (Cosmoshine (registered trademark) A4100; manufactured by Toyo Co., Ltd., 188 μm in thickness and. + -. 2 μm in thickness distribution) having a width of 900mm to form a coating film of the resin varnish. At this time, the linear velocity was 0.8 m/min. The coating film of the resin varnish was dried under the following drying conditions to form a dried coating film: heating was carried out at 80 ℃ for 10 minutes, then at 100 ℃ for 10 minutes, then at 90 ℃ for 10 minutes, and finally at 80 ℃ for 10 minutes. Then, the coating film was peeled off from the PET film, and the raw material optical film 1 was obtained in the form of a film roll having a thickness of 48 μm, a width of 700mm and a length of 500 m. Next, the raw material optical film 1 was heated at 200 ℃ for 25 minutes with a film transverse stretching device called a tenter at a stretching ratio of 0.98 times to obtain a film roll 1 formed of a polyamideimide film having a thickness of 40 μm.

Production example 6: manufacture of film roll 2

The resin varnish 1 obtained in production example 3 was cast on a long PET film substrate (Cosmoshine (registered trademark) A4100; manufactured by Toyo Co., Ltd., 188 μm in thickness and. + -. 2 μm in thickness distribution) having a width of 900mm to form a coating film of the resin varnish. At this time, the linear velocity was 0.8 m/min. The coating film of the resin varnish was dried under the following drying conditions to form a dried coating film: heating was carried out at 80 ℃ for 10 minutes, then at 100 ℃ for 10 minutes, then at 90 ℃ for 10 minutes, and finally at 80 ℃ for 10 minutes. Then, the coating film was peeled off from the PET film, and the raw material optical film 1 was obtained in the form of a film roll having a thickness of 48 μm, a width of 700mm and a length of 500 m. Next, the raw material optical film 1 was heated at 200 ℃ for 25 minutes with a film transverse stretching device called a tenter at a stretching ratio of 0.98 times to obtain a film made of a polyamideimide film having a thickness of 40 μm, and a PET film (having a thickness of 38 μm, an adhesive layer thickness of 15 μm, and a width of 680mm) with an adhesive layer was laminated and wound up to obtain a film roll 2.

Example 1

The photocurable resin composition 1 was applied to the center of one surface of the obtained film roll 1 in a roll-to-roll manner using a bar coater so that the thickness after drying was 10 μm and the width was 650 mm. Then, the mixture was dried in an oven at 80 ℃ for 3 minutes at a concentration of 500mJ/cm²The energy of (2) is irradiated with ultraviolet rays by a high-pressure mercury lamp to cure the ultraviolet rays, thereby forming a cured resin layer having a hard coating function. A pressure-sensitive adhesive layer-attached PET film (having a PET layer thickness of 125 μm, a pressure-sensitive adhesive layer thickness of 10 μm, and a width of 680mm) was laminated on the cured resin layer so that the centers in the width direction were aligned, and wound up, thereby obtaining a laminate 1 having a length of 400m in the form of a film roll. At this time, the winding is performed so that the core side becomes the optical film layer. A part of the wound film roll was cut out, the PET film was peeled off, and the pencil hardness of the cured resin layer was measured, and the result was 2H. In addition, it was determined that no cured tree was formedThe residual solvent content in the optical film portion of the lipid layer was 0.82%.

Example 2

A laminate 2 was obtained in the form of a roll of film in the same manner except that the roll of film 2 was used instead of the roll of film 1. At this time, the laminate is wound so that the optical film side of the laminate becomes the core side. A part of the wound film roll was cut out, the PET film was peeled off, and the pencil hardness of the cured resin layer was measured, and the result was 2H. The residual solvent content in the optical film portion where no cured resin layer was formed was measured, and the result was 0.82%.

Example 3

From the center of one surface of the obtained film roll 1, a film having a width direction of 150mm and an unwinding direction of 200mm was cut. The curable resin composition 1 was applied to both ends in the width direction so that a 5mm portion from the end was masked with a Kapton tape and the thickness after drying was 10 μm and the width was 140mm using a bar coater. That is, 5mm from both ends in the width direction was not coated with the cured resin layer. Then, the mixture was dried in an oven at 80 ℃ for 3 minutes at 500mJ/cm²The energy of (2) is irradiated with ultraviolet rays by a high-pressure mercury lamp to cure the ultraviolet rays, thereby forming a cured resin layer having a hard coating function. A pressure-sensitive adhesive layer-attached PET film (PET layer thickness 125 μm, pressure-sensitive adhesive layer thickness 10 μm, and width 147mm) was laminated on the cured resin layer so that the centers in the width direction were aligned, to obtain a laminate 3. The PET film was peeled off, and the pencil hardness of the cured resin layer was measured, which was 2H. The residual solvent content in the optical film portion where no cured resin layer was formed was measured, and the result was 0.82%.

< curl measurement 1 >

Laminates 1 and 2 having a width direction of 150mm and an unwinding direction of 200mm were cut out from the film rolls 1 and 2 produced in examples 1 and 2, respectively, wound around a core made of polyvinyl chloride having a diameter of 3 inches so that the winding direction was the same as that of the film roll, and left to stand in a dry environment at 90 ℃ for 3 hours. The procedure of winding the core was as described in experiments 1 and 2 below. After peeling from the core, the PET films on both sides were peeled off immediately, and the laminate was placed on a horizontal table to measure the amount of curling at 4 corners. The curl at 4 corners was determined by setting the curl amount when the cured resin layer faced downward to negative and the curl amount when the optical film faced downward to positive, and the average value thereof was set as the curl amount. In the measurement, a JIS 1 grade metal rule was used.

Experiment 1

When winding the laminate around a polyvinyl chloride core, the laminate 1 and 2 are wound so that the optical film side of the laminate becomes the core side, and then the amount of curl is measured in accordance with the procedure for measuring the amount of curl.

Experiment 2

When winding the laminate around a polyvinyl chloride core, the laminate 1 and 2 are wound so that the cured resin layer side of the laminate becomes the core side, and then the amount of curl is measured in accordance with the procedure for measuring the amount of curl.

[ Table 1]

	Laminate 1	Laminate 2
			Experiment 1	5.5mm	3.5mm
Experiment 2	25mm	37mm

< curl measurement 2 >

A laminate 1 cut out from the laminate 1 produced in example 1 and having a width direction of 150mm and an unwinding direction of 200mm, and a laminate 3 produced in example 3 were wound around a core made of polyvinyl chloride having a diameter of 2 inches, respectively, and left to stand in a dry environment at 90 ℃ for 3 hours, so that the winding direction was the same as the film winding direction. At this time, the polyvinyl chloride core was wound so that the core side became the optical film side. Then, immediately after peeling from the core, the PET film on the cured resin layer side was peeled off, and the laminate was placed on a horizontal table to measure the amount of curling at 4 corners. The curl at 4 corners was determined by setting the curl amount when the cured resin layer faced downward to negative and the curl amount when the optical film faced downward to positive, and the average value thereof was set as the curl amount. In the measurement, a JIS 1 grade metal rule was used.

[ Table 2]

	Laminate 1	Laminate 3
			Amount of curl	7mm	5mm

< Water absorption measurement >

A laminated film having a width direction of 100mm and an unwinding direction of 100mm was cut out from the outermost layer portion of the film roll. After drying at 80 ℃ for 3 hours, the mass of the laminated film was measured as the mass W0 before water vapor exposure.

A cylindrical beaker having a diameter of 75mm was prepared, 150g of water was placed therein, and the beaker was placed on a heating plate set at 120 ℃ to boil the water. During boiling, the lid was covered with a metal plate in such a manner that no steam was emitted. After sufficient boiling, the cover of the metal plate is removed, and the metal plate is covered with a previously cut laminated film, and the laminated film is exposed to water vapor. After 5 minutes, the laminated film was removed, and the mass was measured, and the water absorption was calculated as the mass W1 after water vapor exposure using the following formula. The results are shown in Table 2.

[ mathematical formula 2]

Water absorption (%) - (W1-W0)/W1 × 100

Experiment 3

The cover was placed so that the surface in contact with the vapor became an optical film, and the water absorption was measured.

Experiment 4

The cover was placed so that the surface in contact with the vapor became a cured resin layer having a hard coat function, and the water absorption was measured.

[ Table 3]

As is clear from table 3, when the surface in contact with the vapor is an optical film, the water absorption rate is high. Therefore, the optical film absorbs moisture more easily than the cured resin layer and releases moisture easily, and therefore, is affected by humidity in the storage environment. Since the curl amount is measured under the drying condition of 90 ℃, the curl amount is reduced without being affected by moisture in a roll obtained by forming the cured resin layer to the outside so as not to be easily affected by the moisture amount. On the other hand, when the optical film is wound with the optical film facing the outside, moisture is removed at a time in a dry environment of 90 ℃. This can also be said to be because: in the curl measurement in which the curl of the roll was verified in a simulated manner, experiment 1 was better than experiment 2.

Claims

1. A film roll formed by winding a laminate including a laminated film and a protective film 1, the laminated film including:

a cured resin layer laminated on the optical film;

the film roll is wound in the order of the optical film, the cured resin layer, and the protective film 1 from the core side of the roll.

2. A film roll formed by winding a laminate including a laminated film, a protective film 1, and a protective film 2, the laminated film including:

a cured resin layer laminated on the optical film;

the protective film 2 is laminated on the opposite side of the optical film from the cured resin layer,

the film roll is wound in the order of the protective film 2, the optical film, the cured resin layer, and the protective film 1 from the core side of the roll.

3. The film roll according to claim 1 or 2, wherein the cured resin layer has 1 or more functions selected from the group consisting of a hard coat function, an antistatic function, an antiglare function, a low reflection function, an antireflection function, and an antifouling function.

4. The film roll according to any one of claims 1 to 3, wherein the cured resin layer is a UV cured resin layer.