JP6286843B2 - Multilayer film manufacturing method, retardation film laminate manufacturing method, polarizing plate manufacturing method, and IPS liquid crystal panel manufacturing method - Google Patents

Description

  The present invention relates to a multilayer film including a layer having an optical function, a manufacturing method thereof, a manufacturing method of a retardation film laminate, a retardation film, a polarizing plate, and an IPS liquid crystal panel.

  In a liquid crystal display device provided with a liquid crystal panel, sufficient contrast is usually obtained when the screen is viewed from the front. However, when the screen is viewed from an oblique direction that is not parallel to the front direction, the transmission axis of the incident-side polarizer and the transmission axis of the output-side polarizer do not seem to intersect at a predetermined angle. Light leakage may occur without being completely shut off. When light leakage occurs, sufficient black cannot be obtained and the contrast decreases. Therefore, in a liquid crystal display device, an attempt has been made to provide an optical compensation film in order to prevent a reduction in screen contrast.

  A retardation film is usually used as the optical compensation film. As an example of a method for producing a retardation film, a technique is known in which a solution containing a polymer compound is applied on a support and then stretched (for example, Patent Document 1). In such a technique, a technique for setting the residual solvent amount from the coating film to a specific range is also known (Patent Documents 2 and 3). Furthermore, in the production of an optical compensation film using a liquid crystalline compound, there is also known a technique that includes a plurality of substances as a solvent and further makes the relationship between their boiling points predetermined (Patent Document 4).

Special table 2007-500866 gazette JP 2010-224556 A JP 2002-31245 A JP 2010-128270 A

  When a retardation film is produced by coating a solution containing a polymer compound on a support and stretching, coating unevenness is likely to occur due to disorder of the interface in the coating process, thereby causing film thickness unevenness. Is likely to occur. In addition, defects such as bubble streaks and wrinkles are likely to occur in the film due to the disturbance of the interface. In addition, in the stretching process, a problem may occur that the coating film adheres to the gripper of the stretching machine or curls occur on the portion gripped by the film gripper, thereby preventing smooth production. In some cases, the optical performance of the retardation film may be defective. Such a phenomenon is particularly noticeable when a thin retardation film is to be manufactured. In particular, an IPS (in-plane switching) that requires an optical compensation film in which a plurality of retardation films having different optical characteristics are combined. This is a problem in making a thin liquid crystal display device thin.

  Accordingly, an object of the present invention is to produce a coating without causing uneven coating and problems due to interface disturbance, and to reduce the film thickness unevenness of a layer functioning as a retardation film, and to reduce problems when stretching. It is in providing a layer film, its manufacturing method, the manufacturing method of a retardation film laminated body using the same, retardation film, a polarizing plate, and an IPS liquid crystal panel.

As a result of investigations to solve the above problems, the present inventors have found that the above problems can be solved by using a predetermined solvent for the solution constituting the layer functioning as the retardation film. Furthermore, the present inventors have found that in the production of a multilayer film using the solution, good production can be performed by setting production conditions such as drying conditions to predetermined ones. The present invention has been completed based on such findings.
That is, according to the present invention, the following is provided.

[1] a multilayer film comprising a long transparent support, and a functional layer provided on the support,
The functional layer is a layer formed by removing the solvent by drying from a coating film of a solution containing a non-liquid crystalline material and one or more solvents.
The solvent is a poor solvent for the support and a good solvent for the non-liquid crystalline material;
The solution contains only one kind of the solvent, the solubility parameter δ of the solvent is 8.5 to 10.5 (cal / cm ³ ) ^1/2 , and the boiling point Bp of the solvent is 100 to 150 ° C. Or the solution contains two or more kinds of the solvents, the solubility parameter difference Δδ is 0.5 to 1.3 (cal / cm ³ ) ^1/2 and the boiling point difference ΔBp is 55 ℃ or less,
Multi-layer film.
[2] The support is made of a resin having positive intrinsic birefringence,
The non-liquid crystalline material is a resin having positive intrinsic birefringence,
The multilayer film according to [1], wherein one or more of the solvents are ketones or ethers.
[3] The multilayer film according to [1] or [2], wherein a residual solvent amount in the functional layer is 0.05 to 7% by weight.
[4] The non-liquid crystalline material is a resin selected from the group consisting of a polyimide resin, a maleimide resin, a polyamideimide resin, a polycarbonate resin, a polyester resin, a polyurethane urea resin, and a mixture thereof. ] The multilayer film of any one of.
[5] A method for producing a multilayer film comprising a long transparent support, and a functional layer provided on the support,
Applying a solution containing a non-liquid crystalline material and one or more solvents to the support to obtain a coating film;
Removing the solvent from the coating film by drying to obtain the functional layer,
The solvent is a poor solvent for the support and a good solvent for the non-liquid crystalline material;
The solubility parameter of the solvent is 8.5 to 10.5 (cal / cm ³ ) ^1/2 and the boiling point of the solvent is 100 to 150 ° C., or the solution contains two or more kinds of the solvents. And the solubility parameter difference Δδ is 0.5 to 1.3 (cal / cm ³ ) ^1/2 and the boiling point difference ΔBp is 55 ° C. or less.
Production method.
[6] The step of removing the solvent comprises
A drying step (I) for drying the coating film under a windless condition at a temperature of 15 to 25 ° C .;
A drying step of drying the coating film at a temperature TD _(II) at a wind speed of 0.5 to 2.5 m / S, wherein the temperature TD _(II) includes only one kind of the solution; When the solvent is contained, it is Bp-20 ° C. or lower, and when the solution contains two or more kinds of the solvents, it is Bp _H- 20 ° C. or lower (provided that Bp _H is the highest boiling point among the solvents contained in the solution). Drying step (II), which is the boiling point of the higher one,
The manufacturing method according to [5], wherein the functional layer has a thickness of 5 to 30 μm.
[7] A method for producing a retardation film laminate, comprising a step of stretching the multilayer film according to any one of [1] to [4],
The step of stretching includes stretching by transverse stretching,
Production in which the stretching temperature in the stretching step is Tg _S ± 20 ° C. (where Tg _S is the glass transition temperature of the material constituting the support) and the stretching ratio is 1.01 to 3 times. Method.
[8] A retardation film containing a stretched functional layer of the retardation film laminate obtained by the production method of [7],
A retardation film in which the stretched functional layer has negative biaxiality.
[9] A polarizing plate comprising the retardation film according to [8] and a polarizer.
[10] An IPS liquid crystal panel comprising the polarizing plate according to [9] and a liquid crystal cell for IPS.

  According to the present invention, a multilayer film that can be produced without causing coating unevenness and problems due to interface disturbance, has little film thickness unevenness of a layer that functions as a retardation film, and has few problems when stretching. And a method for producing the same, a method for producing a retardation film laminate using the same, a phase difference film, a polarizing plate, and an IPS liquid crystal panel can be provided.

FIG. 1 is a cross-sectional view schematically showing a cross section of a multilayer film according to an embodiment of the present invention cut by a plane perpendicular to the main surface. FIG. 2 is a schematic view schematically showing an example of a production apparatus for producing a multilayer film by forming a functional layer on a support, and further stretching it to produce a retardation film laminate. FIG. 3 is a cross-sectional view schematically showing a cross section of an example of the retardation film laminate (B) used for the production of the composite retardation film, taken along a plane perpendicular to the main surface. FIG. 4 is a cross-sectional view schematically showing a cross section of an example of the composite retardation film taken along a plane perpendicular to the main surface. FIG. 5 is a schematic view schematically showing an example of a production apparatus for producing the retardation film laminate (B). FIG. 6 is a schematic view schematically showing an example of a production apparatus used in the method for producing a composite retardation film. FIG. 7 schematically shows a cross section of an example of the polarizing plate of the present invention obtained by using the composite retardation film 400 and the polarizer shown in FIG. 4 taken along a plane perpendicular to the main surface. It is sectional drawing. FIG. 8 schematically shows a cross section of an example of the liquid crystal panel of the present invention obtained by using the polarizing plate 700 and the liquid crystal cell for IPS shown in FIG. 7 cut along a plane perpendicular to the main surface. It is sectional drawing shown.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

In the following description, “long” means one having a length of at least 5 times the width, preferably 10 times or more, specifically a roll shape. It has a length enough to be wound up and stored or transported.
The “base material” and the “polarizing plate” include not only rigid members but also flexible members such as resin films.

  In the following description, the retardation in the in-plane direction of the film is a value represented by (nx−ny) × d unless otherwise specified. Further, the retardation in the thickness direction of the film is a value represented by {(nx + ny) / 2−nz} × d unless otherwise specified. Here, nx represents a refractive index in a direction (in-plane direction) perpendicular to the thickness direction of the film and giving the maximum refractive index. ny represents the refractive index in the in-plane direction and orthogonal to the nx direction. nz represents the refractive index in the thickness direction. d represents the thickness of the film. These retardations can be measured using a commercially available phase difference measuring device (for example, “KOBRA-21ADH” manufactured by Oji Scientific Instruments, “WPA-micro” manufactured by Photonic Lattice) or the Senarmon method.

In the following description, the expression (meth) acryl means acryl, methacryl or a combination thereof. For example, (meth) acrylic acid means acrylic acid, methacrylic acid or a combination thereof. The (meth) acrylic acid ester means an acrylic acid ester, a methacrylic acid ester, or a combination thereof.
In the following description, “ultraviolet light” means light having a wavelength of 1 nm to 400 nm.

  In the following description, the directions of the elements “parallel”, “vertical”, and “orthogonal” include errors within a range that does not impair the effect of the present invention, for example, ± 5 °, unless otherwise specified. You may go out. Further, “along” in a certain direction means “in parallel” in a certain direction.

  In the following description, the MD direction (machine direction) is the film flow direction in the production line, and is usually parallel to the long direction and the vertical direction of the long film. Further, the TD direction (traverse direction) is a direction parallel to the film surface and perpendicular to the MD direction, and is usually parallel to the width direction and the lateral direction of the long film.

  In the following description, the intrinsic birefringence is positive means that the refractive index in the stretching direction is larger than the refractive index in the direction perpendicular to the stretching direction, and that the intrinsic birefringence is negative It means that the refractive index in the direction is smaller than the refractive index in the direction perpendicular to the stretching direction. The value of intrinsic birefringence can also be calculated from the dielectric constant distribution.

  In the polymer described below, unless otherwise specified, the proportion of the structural unit contained in the polymer is usually a single unit corresponding to the structural unit with respect to the total amount of monomers used in the production reaction of the polymer. It corresponds to the ratio of the mass (preparation ratio).

[1. Multi-layer film]
FIG. 1 is a cross-sectional view schematically showing a cross section of a multilayer film according to an embodiment of the present invention cut by a plane perpendicular to the main surface. As shown in FIG. 1, the multilayer film 10 includes a long and transparent support 11 and a functional layer 12 provided on the upper surface 11U of the support 11.

[1.1. Support]
As the support, a resin film is usually used. Although the kind of resin which forms a support body is not specifically limited, Since a support body is transparent, resin is usually transparent resin. Here, the term “transparent” means that it has a light transmittance suitable for use in an optical member. For example, the total light transmittance measured using a test piece having a thickness of 1 mm is usually 70% or more, preferably 80. % Or more, particularly preferably 90% or more. The total light transmittance can be measured using a spectrophotometer (manufactured by JASCO Corporation, ultraviolet-visible near-infrared spectrophotometer “V-570”) in accordance with JIS K0115.

  Examples of the resin that forms the support include polyolefin resins such as polyethylene resins and polypropylene resins; polymer resins having an alicyclic structure such as norbornene resins; polyimide resins, polyamideimide resins, polyamide resins, and polyresins. Etherimide resin, polyether ether ketone resin, polyether ketone resin, polyketone sulfide resin, polyether sulfone resin, polysulfone resin, polyphenylene sulfide resin, polyphenylene oxide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polyacetal Resin, polycarbonate resin, polyarylate resin, (meth) acrylic resin, polyvinyl alcohol resin, polypropylene resin, cellulosic resin , Epoxy resins, phenol resins, (meth) acrylic acid ester - vinyl aromatic compound copolymer resins, isobutene / N- methylmaleimide copolymer resins, styrene / acrylonitrile copolymer resins. One of these may be used alone, or two or more of these may be combined in any ratio. For example, isobutene / N-methylmaleimide copolymer resin and styrene / acrylonitrile copolymer resin are preferably used in combination as a mixture.

  Among these, a polymer resin having an alicyclic structure, a (meth) acrylic resin, a polycarbonate resin, a (meth) acrylic acid ester-vinyl aromatic compound copolymer resin, and a polyethersulfone resin are selected. Preferred is a resin. These resins are excellent in mechanical strength and can reduce the retardation developed by stretching. In particular, a polymer resin having an alicyclic structure is particularly preferable from the viewpoint that the relationship between the solvent and the non-liquid crystalline material can be easily set to a desired relationship in the present invention.

  The polymer resin having an alicyclic structure is a resin containing a polymer having an alicyclic structure. Further, the polymer having an alicyclic structure is a polymer having a structural unit containing an alicyclic structure as a structural unit of the polymer, a polymer having an alicyclic structure in the main chain, and a side chain. Any polymer having an alicyclic structure can be used. Moreover, the polymer which has an alicyclic structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Among these, a polymer containing an alicyclic structure in the main chain is preferable from the viewpoint of mechanical strength, heat resistance, and the like.

  Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among these, from the viewpoints of mechanical strength, heat resistance and the like, a cycloalkane structure and a cycloalkene structure are preferable, and a cycloalkane structure is particularly preferable.

  The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly preferably per alicyclic structure. Is a range of 15 or less. Thereby, mechanical strength, heat resistance, and film formability are highly balanced, which is preferable.

  The proportion of structural units containing an alicyclic structure in the polymer having an alicyclic structure can be appropriately selected according to the purpose of use, and is preferably 55% by weight or more, more preferably 70% by weight or more. Particularly preferably, it is 90% by weight or more. It is preferable from a heat resistant viewpoint that the ratio of the structural unit containing the alicyclic structure in the polymer which has an alicyclic structure exists in this range.

  Examples of the polymer having an alicyclic structure include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer, and hydrides thereof. Can be mentioned. Among these, norbornene-based polymers are preferable because of good moldability.

  Examples of the norbornene-based polymer include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; An addition polymer of a monomer having a norbornene structure, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof can be given. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Here, “(co) polymer” refers to a polymer and a copolymer.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7. -Diene (common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4. 0.1 ^2,5 . ^{17, 10} ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different, and a plurality thereof may be bonded to the ring. Moreover, the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; and cyclic conjugates such as cyclohexadiene and cycloheptadiene. Dienes and derivatives thereof; and the like. As the other monomer capable of ring-opening copolymerization with a monomer having a norbornene structure, one type may be used alone, or two or more types may be used in combination at any ratio.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer with another monomer copolymerizable with a monomer having a norbornene structure are, for example, a known ring-opening monomer. It can be produced by polymerization or copolymerization in the presence of a polymerization catalyst.

  Examples of the other monomer capable of addition copolymerization with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene and 1-butene, and derivatives thereof; cyclobutene and cyclopentene. And cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene; and the like. Among these, α-olefin is preferable and ethylene is more preferable. Moreover, the other monomer which can carry out addition copolymerization with the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with the monomer having a norbornene structure are, for example, a known addition polymerization catalyst. It can be produced by polymerization or copolymerization in the presence.

  Examples of the monocyclic olefin polymer include addition polymers of a cyclic olefin monomer having a single ring such as cyclohexene, cycloheptene, and cyclooctene.

  Examples of the cyclic conjugated diene polymer include polymers obtained by cyclization reaction of addition polymers of conjugated diene monomers such as 1,3-butadiene, isoprene and chloroprene; cyclic conjugates such as cyclopentadiene and cyclohexadiene. And 1,2- or 1,4-addition polymers of diene monomers; and their hydrides.

  Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon monomers such as vinylcyclohexene and vinylcyclohexane and their hydrides; vinyl aromatic hydrocarbons such as styrene and α-methylstyrene. Hydrogenated product obtained by hydrogenating an aromatic ring portion contained in a polymer obtained by polymerizing a monomer, a vinyl alicyclic hydrocarbon monomer, or a vinyl aromatic hydrocarbon monomer and these vinyl aromatic hydrocarbon monomers. On the other hand, a hydride of an aromatic ring of a copolymer such as a random copolymer or a block copolymer with another copolymerizable monomer can be used. Examples of the block copolymer include a diblock copolymer, a triblock copolymer or a multi-block copolymer having more than that, a gradient block copolymer, and the like.

  The (meth) acrylic resin is a resin containing a (meth) acrylic polymer. The (meth) acrylic polymer means a polymer of (meth) acrylic acid or a (meth) acrylic acid derivative. Examples of the (meth) acrylic polymer include homopolymers and copolymers such as acrylic acid, acrylic acid ester, acrylamide, acrylonitrile, methacrylic acid, and methacrylic acid ester. Moreover, a (meth) acrylic polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Since the (meth) acrylic resin has high strength and is hard, the strength of the laminate can be increased.

  As the (meth) acrylic polymer, a polymer containing a structural unit formed by polymerizing a (meth) acrylic acid ester is preferable. Examples of (meth) acrylic acid esters include alkyl esters of (meth) acrylic acid. Among them, those having a structure derived from (meth) acrylic acid and an alkanol having 1 to 15 carbon atoms or cycloalkanol are preferable, and those having a structure derived from an alkanol having 1 to 8 carbon atoms are more preferable. .

  Specific examples of the acrylate ester include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, sec-butyl acrylate, and t-acrylate. -Butyl, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, and the like. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, methacrylic acid. Examples thereof include t-butyl acid, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, and n-dodecyl methacrylate. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  Furthermore, the (meth) acrylic acid ester may have a substituent such as a hydroxyl group or a halogen atom as long as the effects of the present invention are not significantly impaired. Examples of the (meth) acrylic acid ester having such a substituent include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid 2- Examples include hydroxypropyl, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, and glycidyl methacrylate. Moreover, these substituents may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Further, the (meth) acrylic polymer may be a polymer of only (meth) acrylic acid or (meth) acrylic acid derivatives, and can be copolymerized with (meth) acrylic acid or (meth) acrylic acid derivatives. It may be a copolymer with any arbitrary monomer. Examples of the optional monomer include α, β-ethylenically unsaturated carboxylic acid ester monomers other than (meth) acrylic acid esters, α, β-ethylenically unsaturated carboxylic acid monomers, and alkenyls. Aromatic monomers, conjugated diene monomers, non-conjugated diene monomers, carboxylic acid unsaturated alcohol esters, olefin monomers, and the like can be mentioned. Moreover, arbitrary monomers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  However, the proportion of structural units having a structure formed by polymerizing (meth) acrylic acid or (meth) acrylic acid derivatives in the (meth) acrylic polymer is preferably 55% by weight or more, more preferably 70% by weight. % Or more, particularly preferably 90% by weight or more.

  Of these acrylic polymers, polymethacrylate is preferred, and polymethyl methacrylate is more preferred.

  The polycarbonate resin is a resin containing a polycarbonate polymer. The polycarbonate polymer is a polymer having structural units bonded by a carbonate bond (—O—C (═O) —O—). A polycarbonate polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Among them, the polycarbonate polymer is preferably one containing a structural unit represented by the following formula (I). The structural unit represented by the following formula (I) can be formed by polymerizing bisphenol Z, for example. Examples of such a resin containing a polycarbonate polymer include Lexan manufactured by SABIC.

In formula (I), R ^{1 to} R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, or an aryl group. The alkyl group, cycloalkyl group, and aryl group may be substituted or unsubstituted. Furthermore, the number of carbon atoms of the alkyl group, cycloalkyl group, or aryl group is usually 1-10.
In the formula (I), R ⁹ represents a hydrogen atom, an alkyl group or an aryl group. Here, the carbon atom number of an alkyl group and an aryl group is 1-9 normally.
In formula (I), Z is a residue that, together with the carbon atom to which it is attached, forms a saturated or unsaturated carbocycle having 4 to 11 carbon atoms. Among them, Z is preferably a saturated carbocyclic ring having 6 carbon atoms.

Among those described above, R ¹ (or R ³ ) is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably a methyl group. R ⁶ (or R ⁸ ) is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably a methyl group.
Among them, the structural unit represented by the formula (I) is particularly preferably a structural unit represented by the chemical formula (II) (bisphenol Z unit).

  As the polycarbonate polymer, those further containing a structural unit represented by the following formula (III) in addition to the structural unit represented by the formula (I) are preferable. The structural unit represented by the following formula (III) can be formed by polymerizing bisphenol A, for example. Among these, the structural unit represented by the formula (III) is more preferably a structural unit represented by the formula (IV) or (V).

In the chemical formula (III), R ^{10 to} R ¹⁷ are each independently a hydrogen atom, a halogen atom, an alkyl group, a cycloalkyl group, or an aryl group. Here, the alkyl group, cycloalkyl group, and aryl group may be substituted or unsubstituted. Furthermore, the carbon atom number of an alkyl group, a cycloalkyl group, and an aryl group is 1-10 normally.

  In the combination of the structural unit represented by the formula (I) and the structural unit represented by the formula (III), the amount of the structural unit represented by the formula (III) is preferably 0 with respect to 1 mol of the structural unit represented by the formula (I). .6 mol or more, and preferably 1.5 mol or less. Thereby, a film excellent in heat resistance and flexibility can be formed as a support.

  Moreover, the polycarbonate polymer may contain arbitrary structural units other than the structural unit shown in Formula (I) or Formula (III). However, in the polycarbonate polymer, the proportion of the structural unit represented by formula (I) or formula (III) is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more.

  The (meth) acrylic acid ester-vinyl aromatic compound copolymer resin is a resin containing a copolymer of a (meth) acrylic acid ester and a vinyl aromatic compound. The (meth) acrylic acid ester and the vinyl aromatic compound may be used one by one or may be copolymerized by combining two or more of them at an arbitrary ratio. Moreover, the said copolymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Examples of the (meth) acrylic acid ester include the same examples as those exemplified in the description of the (meth) acrylic resin. Moreover, (meth) acrylic acid ester may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Examples of vinyl aromatic compounds include aromatic monomers having an ethylenically unsaturated bond. Specific examples thereof include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, α-methylstyrene, vinylnaphthalene, and vinylanthracene. Can be mentioned. Moreover, a vinyl aromatic compound may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The polymerization ratio of (meth) acrylic acid ester to vinyl aromatic compound is 1% to 80% by weight of (meth) acrylic acid ester, vinyl aromatic compound from the viewpoint of heat resistance, transparency and strength of the copolymer. It may be 20% to 99% by weight. By making the amount of (meth) acrylic acid ester 1% by weight or more, the strength, heat resistance and transparency of the copolymer can be sufficiently increased, and by making it 80% by weight or less, (meth) acrylic acid ester -The moldability of the vinyl aromatic compound copolymer resin can be improved.

  The copolymer of (meth) acrylic acid ester and vinyl aromatic compound may be a copolymer obtained by further polymerizing any monomer other than (meth) acrylic acid ester and vinyl aromatic compound. As an arbitrary monomer, a conjugated diene compound can be mentioned, for example. Specific examples of the conjugated diene compound include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3- Examples include hexadiene, and particularly preferred are 1,3-butadiene and isoprene. One of these may be used alone, or two or more thereof may be used in combination at any ratio. However, in this copolymer, the proportion of structural units having a structure formed by polymerizing (meth) acrylic acid ester or vinyl aromatic compound is preferably 55% by weight or more, more preferably 70% by weight or more, Especially preferably, it is 90 weight% or more.

  The polyethersulfone resin is a resin containing a polyethersulfone polymer. The polyethersulfone polymer is a polymer in which the main chain is linked by a condensed structure of aromatic bisphenol and dihalogenoarylsulfone. The polyethersulfone polymer can be obtained, for example, by polycondensing aromatic bisphenol and dihalogenoarylsulfone in the presence of a basic catalyst by a polymerization method such as a solution polymerization method or a melt polymerization method. A polyether sulfone polymer may be used individually by 1 type, and may be used combining 2 or more types by arbitrary ratios.

  Examples of the aromatic bisphenol include hydroquinone, 4,4′-dihydroxybiphenyl, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl. Cyclohexane, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -1 -Phenylethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2 -Bis (4-hydroxy-3-tert-butylphenyl) propane, 9,9-bis (4-hydro) Ciphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene, 1,3-bis {2- (4-hydroxyphenyl) propyl} benzene, 1,4-bis {2- (4- Hydroxyphenyl) propyl} benzene, 2,2-bis (4-hydroxyphenyl) -1,1,1-3,3,3-hexafluoropropane and the like. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  Examples of the dihalogeno compound include bis (4-chlorophenyl) sulfone, bis (4-fluorophenyl) sulfone, bis (4-bromophenyl) sulfone, 4-chloro-4 ′-(p-chlorophenyl) diphenylsulfone, 4-fluoro-4 '-(p-fluorophenyl) diphenylsulfone, 4-bromo-4'-(p-bromophenyl) diphenylsulfone, bis (4'-chlorobiphenyl) sulfone, bis (4'-fluorobiphenyl) Sulfone, bis (4′-bromobiphenyl) sulfone, bis (6-chlorobinaphthyl) sulfone, bis (6-fluorobinaphthyl) sulfone, bis (6-bromobinaphthyl) sulfone, bis (4-chloro-3-methylphenyl) Sulfone, bis (4-fluoro-3-methylphenyl) sulfo Bis (4-bromo-3-methylphenyl) sulfone, bis (3-phenyl-4-chlorophenyl) sulfone, bis (3-phenyl-4-fluorophenyl) sulfone, bis (3-phenyl-4-bromophenyl) Examples include sulfone, bis (4-chloro-3-tert-butylphenyl) sulfone, bis (4-fluoro-3-tert-butylphenyl) sulfone, and bis (4-bromo-3-tert-butylphenyl) sulfone. Can do. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  The polyethersulfone polymer may contain an arbitrary structural unit having a structure formed by polymerizing monomers other than aromatic bisphenol and dihalogenoarylsulfone. However, in this copolymer, the proportion of structural units having a structure formed by polymerizing aromatic bisphenol and dihalogenoaryl sulfone is preferably 55% by weight or more, more preferably 70% by weight or more, particularly preferably. 90% by weight or more.

  The resin used as the material for forming the support may contain an optional component other than the above-described polymer. However, the ratio of the above-described polymer in the resin that is a material for forming the support is preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more.

  For example, when the support is a (meth) acrylic resin, the (meth) acrylic resin can include rubber particles. By including the rubber particles, the flexibility of the (meth) acrylic resin can be increased, and the impact resistance of the laminate can be improved. Further, if necessary, the surface roughness of the (meth) acrylic resin layer can be increased with rubber particles, the contact area on the surface can be reduced, and the slipperiness of the surface can be enhanced. In the support, the surface on the functional layer side preferably has a small surface roughness, and therefore, the surface roughness on the surface opposite to the functional layer is preferably roughened.

  Examples of the rubber forming the rubber particles include acrylate polymer rubber, polymer rubber mainly composed of butadiene, and ethylene-vinyl acetate copolymer rubber. Examples of the acrylate polymer rubber include those having butyl acrylate, 2-ethylhexyl acrylate or the like as a main component of a monomer unit. Among these, acrylic acid ester polymer rubber mainly composed of butyl acrylate and polymer rubber mainly composed of butadiene are preferable.

  Further, the rubber particles may contain one type of rubber alone or two or more types of rubber. Further, these rubbers may be mixed uniformly, but may be layered. Examples of rubber particles in which rubber is layered include a core composed of a rubber elastic component obtained by grafting an alkyl acrylate such as butyl acrylate and styrene, and one or both of polymethyl methacrylate and methyl methacrylate and an alkyl acrylate. Examples thereof include particles in which a hard resin layer (shell) made of a polymer forms a layer with a core-shell structure.

  The rubber particles preferably have a number average particle diameter of 0.05 μm or more, more preferably 0.1 μm or more, and preferably 0.3 μm or less, and 0.25 μm or less. Is more preferable. By setting the number average particle diameter within the above range, moderate unevenness can be formed on the surface of the (meth) acrylic resin layer, and the slipperiness of the laminate can be improved.

  The amount of the rubber particles is preferably 5 parts by weight or more and preferably 50 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer. By setting the amount of the rubber particles within the above range, the impact resistance of the laminate can be increased and the handling property can be improved.

  Moreover, as an arbitrary component which resin which becomes the material which forms a support body can contain, a compounding agent is mentioned, for example. Examples of compounding agents are layered crystal compounds; fine particles; antioxidants, heat stabilizers, light stabilizers, weathering stabilizers, UV absorbers, near infrared absorbers and other stabilizers; plasticizers: dyes and pigments, etc. Colorants; antistatic agents; and the like. Moreover, a compounding agent may use one type and may use it combining two or more types by arbitrary ratios. The amount of the compounding agent can be appropriately determined within a range that does not significantly impair the effects of the present invention. For example, the amount is preferably 10 parts by weight or less, more preferably 5 parts by weight or less with respect to 100 parts by weight of the polymer. Preferably, 3 parts by weight or less is more preferable.

The glass transition temperature Tg _S of the material constituting the support is preferably set according to the glass transition temperature of the non-liquid crystalline material constituting the functional layer. Specifically, the difference between the glass transition temperature Tg _S of the support material and the glass transition temperature of the non-liquid crystalline material forming the functional layer is preferably −15 ° C. or higher, more preferably −10 ° C. or higher, Particularly preferably, it is −5 ° C. or more, preferably + 15 ° C. or less, more preferably + 10 ° C. or less, and particularly preferably + 5 ° C. or less. By making the difference in the glass transition temperature of the material forming each layer in the multilayer film within the above range, the stretching treatment can be performed without impairing the followability of the functional layer with respect to the support during the stretching treatment. Thereby, a uniform stretching process can be performed in the functional layer in both the MD direction and the TD direction.

  As the support, those subjected to a surface treatment such as a hydrophilization treatment, a hydrophobization treatment, or a treatment for reducing the solubility of the support may be used as necessary.

  The support may have a single layer structure formed of only one layer, or may have a multilayer structure including two or more layers.

  The thickness of the support in the multilayer film of the present invention is preferably 10 μm or more, more preferably 20 μm or more, particularly preferably 30 μm or more, preferably 200 μm or less, more preferably 150 μm or less, particularly preferably 100 μm or less. . By setting the thickness of the support within the above range, the multilayer film can be stretched to easily obtain a retardation film laminate having desired properties.

[1.2. Functional layer]
The functional layer is a layer formed by removing the solvent from the coating film of a predetermined solution by drying. The functional layer can be formed by applying a predetermined solution on a support to obtain a coating film, and removing the solvent from the coating film by drying.
The solution used for forming the functional layer contains a non-liquid crystalline material and one or more solvents. Therefore, the functional layer can be a layer substantially made of a non-liquid crystalline material.
As the non-liquid crystalline material, a material having positive intrinsic birefringence is usually used. By using a material having positive intrinsic birefringence, a functional layer having optical characteristics useful as a material for a polarizing plate can be easily obtained.
Unlike liquid crystalline materials, non-liquid crystalline materials form a transparent non-oriented layer when coated on the surface of the support, depending on the properties of the non-liquid crystalline material itself, regardless of the orientation of the support. be able to. Thereafter, by stretching the multilayer film, a functional layer oriented in the same direction as an arbitrary stretching direction can be formed. For this reason, even if the said support body is a non-orientation thing, the process of coating an orientation film on the surface, the process of laminating | stacking an orientation film, etc. are not required, for example. Further, an oriented functional layer can be easily obtained without performing a treatment corresponding to the orientation treatment of the liquid crystalline material.

[1.2.1. Non-liquid crystalline material]
As the non-liquid crystal material, a resin having positive intrinsic birefringence is usually used. Further, as this resin, a transparent resin is usually used. Preferred examples of such resins include polyamide resins, polyimide resins, maleimide resins, polyester resins, polyetherketone resins, polyamideimides because of their excellent heat resistance, chemical resistance, transparency, and rigidity. Resins, polycarbonate resins, polyester imide resins, polyurethane urea resins and the like can be mentioned. One of these may be used alone, or two or more of these may be used in combination at any ratio. When two or more kinds of resins are combined, resins having different functional groups such as a mixture of a polyether ketone resin and a polyamide resin may be used in combination. Among such resins, resins selected from the group consisting of polyimide resins, maleimide resins, polyamideimide resins, polycarbonate resins, polyester resins, polyurethaneurea resins, and mixtures thereof are preferred. In particular, a polycarbonate resin and a maleimide resin are particularly preferable from the viewpoint of easily making the relationship between the solvent and the support a desired relationship in the present invention. Specific examples include those described in Japanese Patent No. 3962034, Japanese Patent No. 3897743, Japanese Patent No. 3838522, and Japanese Patent No. 3811175.

  As a preferable polyimide resin, for example, a resin containing a polyimide having a high in-plane orientation and soluble in an organic solvent is preferable. Specifically, for example, it includes a condensation polymerization product of 9,9-bis (aminoaryl) fluorene and an aromatic tetracarboxylic dianhydride disclosed in JP 2000-511296 A, and has the following formula ( Resins containing polyimide containing one or more structural units shown in VI) are preferred.

In formula (VI), each R ^1a independently represents a hydrogen atom; a halogen atom; a phenyl group; a phenyl group substituted with 1 to 4 halogen atoms or an alkyl group having 1 to 10 carbon atoms; and And a group selected from the group consisting of: an alkyl group having 1 to 10 carbon atoms; Among them, as R ^1a , a halogen atom; a phenyl group; a phenyl group substituted with 1 to 4 halogen atoms or an alkyl group having 1 to 10 carbon atoms; and an alkyl group having 1 to 10 carbon atoms; Are preferably selected from.

In the formula (VI), A ^a represents a tetrasubstituted aromatic group having 6 to 20 carbon atoms. Among these Examples ^{A a,} preferably any of the groups of the following (1) to (3).
(1) A tetravalent group having a structure in which a hydrogen atom is removed from each of four carboxyl groups of pyromellitic acid.
(2) A tetravalent group having a structure in which four hydrogen atoms are removed from a polycyclic aromatic compound such as naphthylene, fluorenylene, benzofluorenylene, anthracenylene, or the like, and a substituted derivative thereof. Here, the substituent is an alkyl group having 1 to 10 carbon atoms and a fluorinated derivative thereof, and a halogen atom such as fluorine or chlorine.
(3) A group represented by the formula (VII).

In the formula (VII), ^Ba is a covalent bond, C (R ^2a ) ₂ group, CO group, O atom, S atom, SO ₂ group, Si (C ₂ H ₅ ) ₂ group, N (R ^3a ) ₂ Groups and combinations thereof are shown. R ^2a independently represents a hydrogen atom or a C (R ^4a ) ₃ group. R ^3a independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R ^4a independently represents a hydrogen atom, a fluorine atom or a chlorine atom. In formula (VII), m represents an integer of 1 to 10.

  Preferred maleimide resins include, for example, resins containing a polymer represented by formula (VIII).

In the formula (VIII), R ^b and Q ^b each independently represent a substituted or unsubstituted aliphatic group, aromatic group, heterocyclic group, siloxane group or unsaturated hydrocarbon group.
In the formula (VIII), ^Xb represents a maleimide group capable of active energy ray curing or heat curing.

  Among the polymers represented by the formula (VIII), a polymer having a structure represented by the following formula (IX) or formula (X) is preferable. In the formula (IX) and the formula (X), n independently represents an integer of 1 or more and 10 or less.

Furthermore, examples of the maleimide resin include compounds described in US Patent Application Publication No. 2008/0075961.
These maleimide resins can be obtained from, for example, Air Brown.

  Examples of the polyamideimide resin and the polyester resin include polyamide resins and polyester resins described in JP-T-10-508048. The structural unit contained in the polyamideimide or polyester contained in these polyamideimide resin or polyester resin is represented, for example, by the following chemical formula (XI).

In the formula (XI), Y ^c represents —O— or —NH—.
In formula (XI), each E ^c is independently a covalent bond, an alkylene group having 2 carbon atoms, a halogenated alkylene group having 2 carbon atoms, a CH ₂ group, or a C (CX ^c ₃ ) ₂ group ( here, ^{X c} is a halogen atom or a hydrogen atom.), CO group, O atom, S atom, SO ₂ group, Si ^(R _{c) 2} group, and, selected from the group consisting of N ^{(R c)} groups At least one kind of group, which may be the same or different. In E ^c , R ^c is at least one of an alkyl group having 1 to 3 carbon atoms and a halogenated alkyl group having 1 to 3 carbon atoms, and is in a meta position or a para group with respect to the carbonyl group or the Y ^c group. Is in place.

In formula (XI), ^Ac represents a substituent. The ^Ac is, for example, a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, OR ^c (where R ^c is as defined above). An alkoxy group, an aryl group, a substituted aryl group by halogenation, etc., an alkoxycarbonyl group having 1 to 9 carbon atoms, an alkylcarbonyloxy group having 1 to 9 carbon atoms, or 1 to 12 carbon atoms. Aryloxycarbonyl group, arylcarbonyloxy group having 1 to 12 carbon atoms and substituted derivatives thereof, arylcarbamoyl group having 1 to 12 carbon atoms, and arylcarbonylamino group having 1 to 12 carbon atoms and substituted derivatives thereof Is mentioned. Further, if the A ^c there are multiple, A ^c may be respectively identical or different.

In formula (XI), A ^c ′ represents a substituent. Examples of the A ^c ′ include a halogen atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, a phenyl group, and a substituted phenyl group. Also, ^'if there are a plurality, A ^c' A c respectively may be the same or may be different. Examples of the substituent on the phenyl ring of the substituted phenyl group include a halogen atom, an alkyl group having 1 to 3 carbon atoms, a halogenated alkyl group having 1 to 3 carbon atoms, and combinations thereof.

In formula (XI), t and z represent the number of substitutions for A ^c and A ^c ′, respectively. Said t is an integer of 0-4. Said z is an integer of 0-3.
In Formula (XI), p is an integer of 0 to 3, q is an integer of 1 to 3, and r is an integer of 0 to 3.

  Further, the polyester may include a structural unit represented by the following formula (XII) or formula (XIII).

In the formula (XII) and the formula (XIII), X ^d and Y ^d represent a substituent. X ^d each independently represents a group selected from the group consisting of a hydrogen atom, a chlorine atom and a bromine atom. Y ^d represents a group represented by the following formula (XIV) or formula (XV).

  As specific examples of polyester, “Byron” manufactured by Toyobo Co., Ltd. and “Polyester” manufactured by Nippon Synthetic Chemical Co., Ltd. can be suitably used.

  Examples of polyurethane urea resins include aliphatic cyclic structure-containing polyols, aliphatic cyclic structure-containing polyisocyanates, aliphatic cyclic structure-containing polyamines, and heavy compounds obtained by reacting acrylic compounds having active hydrogen atom-containing groups. Examples of the resin include coalescence. Specific examples thereof include a resin containing a material synthesized by a material described in JP 2011-132548 A and a production method. As a specific example of the polyurethane urea resin, “Tie Force” manufactured by DIC can be suitably used.

  Examples of the polycarbonate resin include the same examples as given in the description of the material forming the support. Specific examples thereof include Iupizeta PCZ series manufactured by Mitsubishi Gas Chemical Company, “FPC2136” manufactured by Mitsubishi Gas Chemical Company, and “Toughzet” manufactured by Idemitsu Kosan Co., Ltd.

  The resin that can be used as the non-liquid crystalline material can contain an optional component in addition to the above-described polymer. However, the ratio of the above-described polymer in the resin that can be used as the non-liquid crystalline material is preferably 55% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more.

  The glass transition temperature of the non-liquid crystalline material is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, particularly preferably 90 ° C. or higher, preferably 180 ° C. or lower, more preferably 160 ° C. or lower, particularly preferably 140 ° C. It is as follows. By forming a functional layer with a non-liquid crystalline material having a glass transition temperature in such a range, a desired retardation can be stably expressed in the functional layer by a stretching treatment, and at a high temperature, high temperature and high humidity. It can be set as the layer excellent in stability in.

The non-liquid crystalline material has a solubility parameter δ of preferably 15 to 30 (cal / cm ³ ) ^1/2 , more preferably 17 to 26 (cal / cm ³ ) ^1/2 . The solubility parameter can be obtained by the Fedors equation described later. When the solubility parameter is within the above range, a coating film of a solution containing a non-liquid crystalline material can be satisfactorily formed, and the thickness unevenness of the functional layer and deformation during stretching can be reduced.

[1.2.2. Functional layer shape]
The thickness of the functional layer in the multilayer film of the present invention is preferably 2 μm or more, more preferably 5 μm or more, preferably 50 μm or less, more preferably 30 μm or less. By setting the thickness of the functional layer within the above range, a multilayer film can be stretched to easily obtain a retardation film laminate having desired properties.

  The functional layer may be provided on the entire surface of one side of the support, or may be provided on a part of one side of the support. However, from the viewpoint of reducing the disorder of winding of the roll when storing and transporting the multilayer film or a retardation film laminate formed by stretching it in a roll shape, the functional layer is formed on the entire surface of the support. It is preferable to provide it.

[1.3. Any layer]
The multilayer film may be provided with an arbitrary layer on the side opposite to the functional layer of the support.

[1.4. Applications of multilayer film]
The multilayer film of the present invention can impart retardation to the functional layer by stretching. Therefore, the multilayer film of the present invention can be used as a material for the method for producing the retardation film laminate of the present invention.

[2. Method for producing multilayer film]
The multilayer film of the present invention can be produced by a production method including the following steps S1 and S2.
(Step S1) A step of applying a solution containing a non-liquid crystalline material and one or more solvents to a support to obtain a coating film.
(Step S2) A step of removing the solvent from the coating film by drying to obtain a functional layer.
Below, the said method is demonstrated as a manufacturing method of the multilayer film of this invention.

[2.1. Step S1: Solvent]
The solvent in the solution used in step S1 satisfies the following requirements C1 and C2, or satisfies the requirements C1 and C3.
(Requirement C1) The solvent is a poor solvent for the support and a good solvent for the non-liquid crystalline material.
(Requirement C2) The solution contains only one kind of solvent, the solubility parameter of the solvent is 8.5 to 10.5 (cal / cm ³ ) ^1/2 , and the boiling point of the solvent is 100 to 150 ° C. .
(Requirement C3) The solution contains two or more solvents, the difference Δδ between the solubility parameters of the two or more solvents is 0.5 to 1.3 (cal / cm ³ ) ^1/2 , and two or more types The difference ΔBp in the boiling points of the solvents is 55 ° C. or less.

  In the requirement C1, whether or not the solvent is a poor solvent for the support is determined according to the following criteria. That is, when 0.01 g of a support sample is added to 10 g of solvent at 25 ° C., if the solution becomes cloudy or the sample remains in the solution, it is determined that “the solvent is a poor solvent for the support”. To do. When the solution is not cloudy and the sample does not remain in the solution, it is determined that “the solvent is not a poor solvent for the support”.

  In requirement C1, whether or not the solvent is a good solvent for the non-liquid crystal material is determined according to the following criteria. That is, when 1 g of a non-liquid crystalline material sample is added to 9 g of solvent at 25 ° C., if the solution does not become cloudy, it is determined that “the solvent is a good solvent for the non-liquid crystalline material”. When the solution becomes turbid or when the non-liquid crystalline material gels or swells, it is determined that “the solvent is not a good solvent for the non-liquid crystalline material”.

  When the solution contains two or more types of solvents, when the solvent substantially contained in the solution satisfies the requirement C1, it is determined that the entire solvent satisfies the requirement C1. When there are two or more types of solvents substantially contained in the solution, when each of the two or more types of solvents satisfies the requirement C1, it is determined that the entire solvent satisfies the requirement C1. The solvent substantially contained in the solution means a solvent that occupies 5% by weight or more of the total amount of the solvent in the solution.

In the requirements C2 and C3, the solubility parameter δ of the solvent is represented by the square root of the cohesive energy density (CED) between molecules, and the larger the solubility parameter value, the higher the polarity.
Assuming that the force acting between the solvent and the solute is only an intermolecular force, the solubility parameter is used as a measure for representing the intermolecular force. Therefore, the smaller the difference in solubility parameter, the greater the solubility.
In the present application, the value obtained by the Fedors equation is adopted as the solvent solubility parameter. The solubility parameter value δi of a certain component i can be generally calculated using the Fedors equation shown below.
δi = [Ev / V] ^1/2 = [Δei / Δvi] ^1/2
Ev: Evaporation energy V: Molar volume Δei: Evaporation energy of atom or atomic group of i component Δvi: Molar volume of atom or atomic group of i component Atom and atomic group evaporation energy Δei and molar volume Δvi are proposed by Fedors (RF Fedors: Polym. Eng. Sci., 14 (2), 147-154 (1974)), based on this, the solubility parameter value can be calculated by the above formula. Moreover, when one molecule | numerator contains the some component i, according to a usual method, the sum of (DELTA) ei and (DELTA) vi can be calculated | required and a solubility parameter can be calculated based on the value of the said sum total.

In Requirement C2, “the solution contains only one type of solvent” means that the solution substantially contains only one type of solvent. That is, when there is substantially only one type of solvent in the solution, the solubility parameter δ of the solvent is 8.5 to 10.5 (cal / cm ³ ) ^1/2 and the boiling point Bp of the solvent Is 100 to 150 ° C., it is determined that the requirement C2 is satisfied. In requirement C2, the solubility parameter δ is preferably 8.7 to 10.3 (cal / cm ³ ) ^1/2 , more preferably 9.0 to 10.0 (cal / cm ³ ) ^1/2 . is there. The boiling point Bp is preferably 100 to 145 (cal / cm ³ ) ^1/2 , more preferably 100 to 135 (cal / cm ³ ) ^1/2 .

In the requirement C3, the phrase “the solution contains two or more types of solvents” refers to a case where there are two or more types of solvents substantially contained in the solution. When there are three or more solvents substantially contained in the solution, Δδ is the difference between the maximum and minimum solubility parameters σ of those solvents, and ΔBp is the boiling point of those solvents. Is the difference between the largest and smallest. In requirement C3, the difference Δδ in solubility parameter is preferably 0.55 to 1.28 (cal / cm ³ ) ^1/2 , more preferably 0.60 to 1.26 (cal / cm ³ ) ^{1 / 2} . The difference in boiling point ΔBp is preferably 35 ° C. or less, more preferably 25 ° C. or less.

  When the solvent in the solution satisfies the requirements C1 and C2 or the requirements C1 and C3, the coating film of the solution is uniformly formed and dried without whitening in the production of the multilayer film. As a result, uneven thickness of the functional layer and deformation at the time of stretching the multilayer film can be reduced.

As the solvent in the solution, those satisfying the requirements C1 and C2 or the requirements C1 and C3 can be appropriately selected in accordance with the non-liquid crystalline material and the support.
Specific examples of solvents that can be used for such selection are shown in Table 1 below. In Table 1, each solvent is based on polycarbonate resin A (PC resin A), polycarbonate resin B (PC resin B), and bismaleimide resin, which are non-liquid crystalline materials used in Examples of the present application. Whether or not it is a good solvent and whether or not it is a poor solvent for the norbornene-based resin that is the material of the support used in the examples of the present application are also described.

  Among those listed in Table 1, solvents selected from the group consisting of ketones, esters, ethers and combinations thereof are preferred, specifically, from cyclopentanone, 1,4-dioxane, ethyl acetate, and combinations thereof. A solvent selected from the group consisting of

  In particular, in the present invention, the support is made of a resin having positive intrinsic birefringence, the non-liquid crystalline material is a resin having positive intrinsic birefringence, and at least one of the solvents is ketone or Ether is preferred. By having such a combination, the surface state is stabilized without whitening during the formation of the coating film, and when the film is further stretched, excellent retardation expression of the multilayer film can be obtained.

[2.2. Step S1: Solution]
The concentration of the non-liquid crystalline material in the solution is preferably 0.5% by weight or more, more preferably in consideration of the coating property to the support (for example, the degree of foreign matter contamination, unevenness or streaks during coating). Is 1% by weight or more, particularly preferably 2% by weight or more, preferably 50% by weight or less, more preferably 40% by weight or less, and particularly preferably 30% by weight or less. By setting the concentration to be not less than the lower limit of the above range, the viscosity of the solution can be increased and the solution can be developed with a desired thickness. Moreover, by making it below an upper limit, the viscosity of a solution can be made low and the deterioration of the surface state of the layer of a solution can be prevented. Specifically, the solution viscosity at the time of coating is preferably 10 to 100 (mPa · s). The solution viscosity can be measured with a conventional viscometer (B-type, E-type, etc.).

  The solution may contain a compounding agent such as a surfactant in addition to the non-liquid crystalline material and the solvent.

[2.3. Process S1 Conditions]
The application of the solution in step S1 can be performed by a method such as spin coating, roll coating, die coating, or blade coating. The thickness of the coating film can be appropriately adjusted so that the thickness of the functional layer obtained after drying and the thickness of the functional layer after stretching are set to desired values.

[2.4. Step S2]
In step S2, the solvent is removed from the coating film by drying to obtain a functional layer. Here, the removal of the solvent is preferably performed so that the amount of the solvent remaining in the coating film is as small as possible. However, it is not always necessary to remove all the solvent, and the solvent may remain in the obtained functional layer. Specifically, the amount of residual solvent in the functional layer is ideally zero, but 0.05% by weight or more of residual solvent may be present. The upper limit of the residual solvent amount in the functional layer is preferably 7% by weight or less, more preferably 6.8% by weight or less, and still more preferably 6.5% by weight or less.

Removal of the solvent in step S2
A drying step (I) for drying the coating film under a windless condition at a temperature of 15 to 25 ° C .;
It is preferable to include a drying step (II) in which the coating film is dried at a predetermined temperature TD _(II) at a wind speed of 0.5 to 2.5 m / S. When step S2 includes drying steps (I) and (II), the occurrence of uneven thickness of the functional layer, bubble streaks, and wrinkles can be further reduced.

The drying step (I) is preferably performed immediately after the coating film is formed in step S1. Specifically, for example, after the coating film is formed, the drying step (I) is preferably entered within 0.5 seconds, more preferably within 1.0 seconds.
In the drying step (I), “no wind” means that the airflow in the environment for transporting the film is 0.05 m / s or less, preferably 0.02 m / s or less.

In the drying step (II), the temperature TD _(II) is based on the boiling point Bp when the solution contains only one kind of solvent, and when the solution contains two or more kinds of solvents, It is a value determined based on the boiling point Bp _{H of the} higher one. When the solution contains only one kind of solvent, TD _(II) is Bp-20 ° C or lower, preferably Bp-10 ° C or lower. On the other hand, when the solution contains two or more kinds of solvents, TD _(II) is Bp _H −20 ° C. or lower, preferably Bp _H −10 ° C. or lower.

  The time for performing each of the drying step (I) and the drying step (II) is preferably 10 seconds to 60 minutes, and more preferably 30 seconds to 30 minutes.

In step S2, in addition to the drying steps (I) and (II), an additional drying step can be performed. For example, in addition to the drying step (I) and the drying step (II) immediately after that, an additional drying step may be performed.
When step S2 includes drying step (I) and drying step (II), the thickness of the functional layer formed by the manufacturing method including step S2 is preferably 5 to 30 μm. When the thickness of the functional layer is within this range, the effect of improving the quality of the functional layer by the drying steps (I) and (II) can be obtained more favorably.

[3. Method for producing retardation film laminate]
The manufacturing method of the retardation film laminated body of this invention includes the process of extending | stretching the multilayer film of the said this invention.
Stretching can be performed on a long multilayer film by longitudinal stretching (stretching in the longitudinal direction of the film), lateral stretching (stretching in the width direction of the film), oblique stretching, or a combination thereof. More specific examples include a method of uniaxial stretching in the MD direction using the difference in peripheral speed between rolls (longitudinal uniaxial stretching); a method of uniaxial stretching in the TD direction using a tenter stretching machine (lateral uniaxial stretching). A method of sequentially performing longitudinal uniaxial stretching and transverse uniaxial stretching (sequential biaxial stretching); a method of simultaneously performing longitudinal uniaxial stretching and transverse uniaxial stretching (simultaneous biaxial stretching); a method of stretching in an oblique direction with respect to the MD direction ( Diagonal stretching); Here, “oblique direction” means a direction that is neither parallel nor orthogonal. From the viewpoint of obtaining a desired slow axis direction, it is preferable to perform transverse stretching.

  The transverse stretching can be preferably performed with a tenter stretching machine. The tenter stretching machine generally includes a pair of rails and a gripper that can move along the rails. The rail has a rail widening portion in which the rail width is increased in a taper shape in the TD direction toward the downstream side in the MD direction of the belt-like film. In such a tenter stretching machine, the belt-shaped film can be stretched in the TD direction by gripping both ends of the film in the TD direction with a gripper and running the gripper along the rail.

The stretching temperature in the stretching step can be appropriately set from the viewpoints of optical properties imparted to the functional layer, ease of stretching, and the like. For example, Tg _S which is the glass transition temperature of the material constituting the support can be set as a reference. Specifically, the stretching temperature is preferably Tg _S ± 20 ° C. By performing stretching at such a stretching temperature, smooth stretching can be performed, and desired optical properties can be uniformly imparted to the functional layer. Further, by performing stretching at such a stretching temperature, it is possible to reduce the expression of optical anisotropy in the support, whereby the optical properties of the stretched functional layer can be reduced without peeling the support. It becomes possible to monitor.

  The draw ratio in the drawing step can be appropriately set from the viewpoint of the optical properties to be imparted to the functional layer. Specifically, the draw ratio can be preferably 1.01 to 3 times, more preferably 1.02 to 2.7 times. By setting it as this draw ratio, a desired optical property can be uniformly provided to a functional layer.

  In the method for producing a retardation film laminate of the present invention, since the multilayer film of the present invention having a specific functional layer is stretched, it is possible to achieve production with less occurrence of deformation during stretching. Specifically, at the time of stretching, adhesion between the film and the gripper is small, and problems such as curling and peeling of the functional layer in a portion gripped by the film gripper can be reduced.

The method for producing a retardation film laminate of the present invention may include steps other than those described above.
For example, after stretching, a relaxation step may be performed as necessary. In the relaxation step, the stretched support is held at a predetermined temperature for a predetermined time to shrink the support. The relaxation rate in this case is preferably within 20%, the holding temperature is in the range of the glass transition temperature ± 30 ° C. of the material forming the support, and the holding time is 1 second to 60 seconds.

  Moreover, for example, after stretching, the obtained retardation film laminate is cooled to room temperature as necessary. The cooling rate and the cooling means are not particularly limited. However, if the tension at the time of stretching is abruptly released before cooling, wrinkles are likely to occur in the obtained retardation film laminate, and therefore it is preferable to carry out part or all of the cooling step before releasing the tension. .

  The obtained retardation film laminate is usually wound into a roll and stored. In the retardation film laminate obtained by such a production method, the variation in the thickness of the functional layer is small, and the retardation of the functional layer is uniform.

[3.1. Specific example of manufacturing method]
The specific example of the manufacturing method of the multilayer film of this invention and the manufacturing method of the retardation film laminated body of this invention using the multilayer film of this invention is demonstrated with reference to drawings.
FIG. 2 is a schematic view schematically showing an example of a production apparatus for producing a multilayer film by forming a functional layer on a support, and further stretching it to produce a retardation film laminate. As shown in FIG. 2, the manufacturing apparatus 200 includes a feeding device 201, a coating head 210, a dryer 220, a stretching device 230, and a winding device 202.

  In operation, the support 11 fed from the feeding device 201 is subjected to a surface treatment such as a hydrophilization treatment as necessary, and then conveyed to the coating head 210. The coating head 210 applies a solution containing a non-liquid crystalline material and a solvent on the support 11 to form a coating film (step S1).

  The support 11 provided with the coating film is immediately conveyed to the dryer 220 thereafter. The dryer 220 has four chambers 220A to 220D. Each of the four chambers 220 </ b> A to 220 </ b> D includes a casing that encloses the film to be conveyed, a heating device, a blower device, and an exhaust device (not shown). Accordingly, the drying process under different conditions can be sequentially performed in each of the four chambers 220A to 220D. Specifically, the drying step (I) and the drying step (II) described above can be performed in the chambers 220A and 220B, respectively, and any subsequent drying step can be performed in the chambers 220C and 220D. Thereby, the solvent is removed from the coating film by drying to obtain a functional layer, and the multilayer film 10 including the support 11 and the functional layer 12 can be obtained (step S2).

  Subsequently, the multilayer film 10 is transported to the stretching device 230 where it is stretched to produce the retardation film laminate 100. The manufactured retardation film laminate 100 can be wound up by a winding device 202 to form a roll, which can be subjected to further processes.

[3.2. Retardation film laminate]
By the method for producing a retardation film laminate of the present invention, a retardation film laminate including a stretched support and a stretched functional layer is obtained. In the present application, when it is clear from the context, the support and functional layer before stretching in the multilayer film of the present invention, and the support and functional layer after stretching in the retardation film laminate. May be simply referred to as a support and a functional layer without distinction.

  In the retardation film laminate, the in-plane retardation of the support at a wavelength of 550 nm is preferably 300 nm or less, more preferably 200 nm or less, and particularly preferably 100 nm or less. By reducing the retardation in the in-plane direction of the support, it is possible to monitor the retardation of only the functional layer while performing a stretching treatment when producing a multilayer film. In particular, the support preferably has optical isotropy.

  In the retardation film laminate, the functional layer preferably has negative biaxiality. That is, it is preferable that the refractive indexes nx, ny and nz satisfy the relationship of nx> ny> nz. Since the functional layer has negative biaxiality, a retardation film combining a functional layer and a positive biaxial layer (described later) is used as an optical compensation film, so that the contrast of the IPS liquid crystal panel is effectively reduced. It becomes possible to improve.

  In the retardation film laminate, the retardation in the in-plane direction of the functional layer at a wavelength of 550 nm is preferably 50 nm or more, more preferably 70 nm or more, preferably 150 nm or less, more preferably 120 nm or less. When the retardation in the in-plane direction of the functional layer is within this range, production by stretching can be easily performed.

  In the retardation film laminate, the retardation in the thickness direction of the functional layer at a wavelength of 550 nm is preferably 40 nm or more, more preferably 60 nm or more, preferably 150 nm or less, more preferably 120 nm or less. When the retardation in the thickness direction of the functional layer is within this range, production by stretching the multilayer film can be easily performed.

  Here, a quotient obtained by dividing “retardation at a wavelength of 550 nm of the support” by “thickness of the support” is “I”. Further, a quotient obtained by dividing “retardation of functional layer at wavelength of 550 nm” by “thickness of functional layer” is “J”. In this case, I <J is preferable, 3I <J is more preferable, 5I <J is further preferable, and 10I <J is particularly preferable. By selecting a material that satisfies the relationship between the value I and the value J, it is possible to accurately measure the retardation of only the functional layer while performing a stretching process when producing a multilayer film.

  The variation in thickness in the plane of the functional layer is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less of the average thickness of the functional layer. Here, the thickness variation means a difference between the maximum value and the minimum value of the thickness. By realizing such an excellent thickness accuracy, it is possible to obtain a laminate and a retardation film that exhibit uniform optical characteristics in the MD direction and the TD direction. Such thickness accuracy can be realized, for example, by manufacturing a multilayer film by a manufacturing method in which the above-described coating and stretching are combined.

  The peel force between the support and the functional layer is preferably 0.05 N / 20 mm or less, more preferably 0.03 N / 20 mm or less, and particularly preferably 0.01 N / 20 mm or less. The peeling force can be measured according to JIS K6855-2. By reducing the peeling force in this way, the support can be peeled from the laminate, and a retardation film can be easily produced. The lower limit of the peeling force is preferably 0.001 N / 20 mm or more, more preferably 0.003 N / 20 mm or more, and particularly preferably 0.005 N / 20 mm or more. Such a small peeling force can be realized, for example, by appropriately selecting a combination of materials for the support and the functional layer using materials that are not compatible with each other.

  The thickness of the support in the retardation film laminate of the present invention is preferably 10 μm or more, more preferably 20 μm or more, particularly preferably 30 μm or more, preferably 200 μm or less, more preferably 150 μm or less, particularly preferably 100 μm or less. It is. By setting the thickness of the support to be equal to or more than the lower limit of the above range, it is possible to prevent stretching unevenness. Moreover, industrial productivity can be improved by setting it as below an upper limit so that the tension | tensile_strength of a support body may not become excessive.

  The thickness of the functional layer in the retardation film laminate of the present invention is preferably 0.1 μm or more, more preferably 1 μm or more, and preferably 40 μm or less from the viewpoint of improving scratch resistance, handling properties and thin film properties. Preferably it is 30 micrometers or less. By setting the thickness of the functional layer within this range, the retardation film can be made thin and the retardation film can be excellent in high temperature durability.

[4. Retardation film]
The retardation film of this invention contains the extended | stretched functional layer of the retardation film laminated body obtained by the said manufacturing method. That is, the retardation film laminate obtained by the above production method may be used as it is as the retardation film of the present invention, and only from the stretched functional layer obtained by peeling the support from the retardation film laminate. The retardation film obtained may be used as the retardation film of the present invention. Furthermore, the retardation film containing the stretched functional layer and the arbitrary layer obtained by laminating an arbitrary layer is used as the retardation film of the present invention. It is good.

[4.1. Composite retardation film]
As a preferred embodiment of the retardation film of the present invention, a retardation film (hereinafter referred to as “composite”) having a combination of the functional layer having negative biaxiality described above and the retardation layer having positive biaxiality described above. A retardation film ”). The retardation layer having positive biaxiality in the composite retardation film is produced as a retardation film laminate having a retardation layer having positive biaxiality and a protective layer provided on one side or both sides thereof. (In the following, the retardation film laminate is distinguished from the retardation film laminate of the present invention described above, and is referred to as “retardation film laminate (B)”. The retardation layer having positive biaxiality is referred to as “retardation layer (B1)”, and the protective layer is sometimes referred to as “protective layer (B2)”. One or more of the protective layers (B2) may be peeled off from the retardation film laminate (B) as necessary, and the remainder may be bonded to the retardation film of the present invention to form a composite retardation film. .

  The retardation layer (B1) is a layer having positive biaxiality. That is, it is a layer whose refractive indexes nx, ny and nz satisfy the relationship of nz> nx> ny. As a result, it is possible to effectively improve the contrast of the IPS liquid crystal panel by using a retardation film in which a functional layer having negative biaxiality and the retardation layer (B1) are combined as an optical compensation film. is there.

An example of the retardation film laminate (B) and an example of the composite retardation film are shown in FIGS. 3 and 4, respectively. FIG. 3 is a cross-sectional view schematically showing a cross section of an example of the retardation film laminate (B) used for the production of the composite retardation film, taken along a plane perpendicular to the main surface. FIG. 4 is a cross-sectional view schematically showing a cross section of an example of the composite retardation film taken along a plane perpendicular to the main surface.
In FIG. 3, a retardation film laminate (B) 300 includes a retardation layer (B1) 301 and layers 302A and 302B which are a pair of protective layers (B2) provided on both surfaces thereof. By adopting such a structure having the protective layer (B2) on both sides, even if a material that is easily damaged by stretching is adopted as the material of the retardation layer (B1), it is easy to produce by co-stretching. It can be carried out.
In FIG. 4, the composite retardation film 400 has a retardation film laminate 100 and a multilayer film (B ′) 310. The retardation film laminate 100 has a stretched support 111 and a stretched functional layer 112. The multilayer film (B ′) 310 is formed by peeling the protective layer 302B from the composite film (B) 300, and includes a retardation layer (B1) 301 and a protective layer (B2) 302A. . The functional layer 112 and the retardation layer (B1) 301 are bonded via an adhesive layer 401. Thus, the thickness of the entire composite retardation film can be reduced by adopting a configuration in which the protective layer 302B is peeled off and the retardation layer (B1) 301 is directly bonded.

[4.2. Retardation layer (B1)]
Preferable examples of the material of the retardation layer (B1) include a non-liquid crystalline material having a negative intrinsic birefringence. As the non-liquid crystalline material having a negative intrinsic birefringence, a resin having a negative intrinsic birefringence is usually used. Further, as this resin, a transparent resin is usually used. As such a resin, a resin including a polymer obtained by polymerizing one or more monomers selected from the group consisting of styrenes, styrenes-maleic acid, maleimides, and (meth) acrylic acid esters is preferable. In this case, the polymer may be a homopolymer or a copolymer. Since such a polymer usually has a negative intrinsic birefringence, the intrinsic birefringence of the resin containing it can also be made negative.

  Here, styrenes mean styrene and styrene derivatives. Examples of the styrene derivative include those in which a substituent is substituted at the benzene ring or α-position of styrene. Specific examples of styrene derivatives include alkyl styrene such as methyl styrene and 2,4-dimethyl styrene; halogenated styrene such as chlorostyrene; halogen-substituted alkyl styrene such as chloromethyl styrene; alkoxy styrene such as methoxy styrene; Can be mentioned. Here, one kind of styrene may be used alone, or two or more kinds may be used in combination at any ratio.

  In particular, the polystyrene polymer is preferably a polystyrene polymer having a syndiotactic structure. The polystyrene-based polymer having a syndiotactic structure has high heat resistance, can suppress heat shrinkability, and can stably develop desired retardation by stretching.

  Here, the polystyrene polymer has a syndiotactic structure means that the stereochemical structure of the polystyrene polymer has a syndiotactic structure. The syndiotactic structure is a three-dimensional structure in which phenyl groups as side chains are regularly and alternately arranged in opposite directions in the Fischer projection formula with respect to the main chain formed by carbon-carbon bonds. Say. A polystyrene polymer having a syndiotactic structure has a low specific gravity and excellent properties such as hydrolysis resistance, heat resistance and chemical resistance as compared with a conventional atactic polystyrene polymer.

The tacticity (stericity) of the polystyrene-based polymer can be quantified by an isotope carbon nuclear magnetic resonance method ( ¹³ C-NMR method). ^The tacticity measured by the ¹³ C-NMR method can be indicated by the existence ratio of a plurality of consecutive structural units. Generally, for example, when there are two consecutive structural units, it is a dyad, when it is 3, it is a triad, and when it is 5, it is a pentad. In this case, the polystyrene-based polymer having a syndiotactic structure usually has a syndiotacticity of 75% or more, preferably 85% or more in racemic dyad, or usually 30% or more in racemic pentad. It preferably means having a syndiotacticity of 50% or more.

  For example, a polystyrene polymer having a syndiotactic structure can polymerize styrenes using a titanium compound and a condensation product of water and trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent. (See Japanese Patent Application Laid-Open No. 62-187708). Poly (halogenated alkylstyrene) may be produced, for example, by the method described in JP-A-1-46912.

  The weight average molecular weight of a polymer obtained by polymerizing one or more monomers selected from the group consisting of styrenes, styrenes-maleic acid, maleimides and (meth) acrylic acid esters is preferably 130,000 or more, more preferably It is 140,000 or more, particularly preferably 150,000 or more, preferably 300,000 or less, more preferably 270,000 or less, and particularly preferably 250,000 or less. With such a weight average molecular weight, the glass transition temperature of the polymer can be increased, and the heat resistance of the laminate can be stably improved.

  The glass transition temperature of a polymer obtained by polymerizing one or more monomers selected from the group consisting of styrenes, styrenes-maleic acid, maleimides, and (meth) acrylic acid esters is preferably 85 ° C. or more, more preferably 90 ° C or higher, particularly preferably 95 ° C or higher. By increasing the glass transition temperature in this manner, the glass transition temperature of the non-liquid crystalline material having a negative intrinsic birefringence forming the retardation layer (B1) is effectively increased, thereby stabilizing the heat resistance of the retardation film. Can be improved. Further, from the viewpoint of stably and easily producing the laminate, the glass transition temperature is preferably 160 ° C. or lower, more preferably 155 ° C. or lower, and particularly preferably 150 ° C. or lower.

  Furthermore, the non-liquid crystalline material having a negative intrinsic birefringence that forms the retardation layer (B1) is one type selected from the group consisting of the above-mentioned styrene, styrene-maleic acid, maleimides, and (meth) acrylic acid esters. A mixture containing one or more polymers selected from the group consisting of a polycarbonate polymer, a polyester polymer and a polyarylene ether polymer in combination with a polymer obtained by polymerizing the above monomers is preferable. By combining a polycarbonate polymer, a polyester polymer, or a polyarylene ether polymer, it is possible to increase the strength of the retardation layer (B1), control the glass transition temperature, and control optical properties. .

  Examples of the polycarbonate polymer include the same examples as mentioned in the description of the material forming the support. Here, a polycarbonate polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  As described above, a polymer obtained by polymerizing at least one monomer selected from the group consisting of styrenes, styrenes-maleic acid, maleimides, and (meth) acrylic acid esters, polycarbonate polymers, polyester polymers, and Among the combinations with one or more polymers selected from the group consisting of polyarylene ether polymers, it is particularly preferable to combine a polystyrene polymer and a polyarylene ether polymer.

  Polymers obtained by polymerizing one or more monomers selected from the group consisting of styrenes, styrenes-maleic acid, maleimides and (meth) acrylic acid esters, polycarbonate polymers, polyester polymers, and polyarylene ether polymers The weight ratio with one or more polymers selected from the group consisting of is preferably 90:10 to 55:45, more preferably 85:15 to 60:40, and particularly preferably 80:20. ~ 65: 35. When the weight ratio is in this range, desired retardation and desired optical properties can be easily expressed in the retardation layer (B1) by stretching.

  The non-liquid crystalline material having a negative intrinsic birefringence forming the retardation layer (B1) is at least one selected from the group consisting of styrenes, styrenes-maleic acid, maleimides, and (meth) acrylic acid esters. In addition to a polymer obtained by polymerizing monomers, and one or more kinds of polymers selected from the group consisting of a polycarbonate polymer, a polyester polymer, and a polyarylene ether polymer, an optional component may be included. Examples of the optional component include an antioxidant, an ultraviolet absorber, a light stabilizer, and a crosslinking agent. However, in the non-liquid crystalline material having a negative intrinsic birefringence forming the retardation layer (B1), one kind selected from the group consisting of styrenes, styrenes-maleic acid, maleimides and (meth) acrylic acid esters The ratio of one or more polymers selected from the group consisting of a polymer obtained by polymerizing the above monomers, and a polycarbonate polymer, a polyester polymer and a polyarylene ether polymer is preferably 50% by weight or more, more preferably Is 80% by weight or more, particularly preferably 90% by weight or more.

  The glass transition temperature of the non-liquid crystalline material having a negative intrinsic birefringence forming the retardation layer (B1) is preferably 115 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher. The higher the glass transition temperature of the non-liquid crystalline material having a negative intrinsic birefringence, the better the heat resistance of the retardation film. However, if the glass transition temperature is excessively high, it may not be easy to produce a laminate. Therefore, the glass transition temperature of a non-liquid crystalline material having a negative intrinsic birefringence is usually 200 ° C. or lower.

  The tensile elongation at break of the retardation layer (B1) is preferably 20% or less, more preferably 15% or less, and particularly preferably 10% or less. The tensile breaking elongation can be measured according to JIS K7162. In general, a non-liquid crystalline material having negative intrinsic birefringence has low mechanical strength. On the other hand, since the retardation film laminate (B) includes the protective layer (B2), even the retardation layer (B1) having a low mechanical strength can be hardly damaged. Further, the example of the composite retardation film has a laminated structure including a support, a functional layer, an adhesive layer, a retardation layer (B1), and a protective layer (B2) in this order. Damage to the layer (B1) can be effectively prevented. Therefore, the low tensile rupture elongation of the layer (B1) as described above prevents damage to the layer (B1), and makes the effects of improving handling and impact resistance more prominent. There is technical significance.

  The retardation layer (B1) has a retardation in the in-plane direction at a wavelength of 550 nm, preferably 40 nm or more, more preferably 50 nm or more, preferably 150 nm or less, more preferably 100 nm or less. When the retardation in the in-plane direction of the retardation layer (B1) is within this range, the retardation film laminate (B) can be easily produced by stretching.

Further, the retardation layer (B1) has an in-plane retardation Re _B1 (450) at a wavelength of 450 nm and an in-plane retardation Re _B1 (550) at a wavelength of 550 nm, and Re _B1 (450) / Re _B1 ( 550)> 1.00 is preferable. When Re _B1 (450) and Re _B1 (550) satisfy this relationship, a retardation film capable of exhibiting a compensation effect for the IPS liquid crystal cell in a wide wavelength range can be obtained.

The retardation layer (B1) has a retardation Rth _B1 (550) in the thickness direction at a wavelength of 550 nm, preferably −150 nm or more, more preferably −130 nm or more, preferably −50 nm or less, more preferably − 60 nm or less. When the retardation Rth _B1 (550) in the thickness direction of the retardation layer (B1) is within this range, the retardation film laminate (B) can be easily produced by stretching.

  The in-plane slow axis of the retardation layer (B1) is usually parallel to the in-plane slow axis of the functional layer. Thereby, optical compensation can be effectively performed in the IPS liquid crystal panel, and the contrast of the liquid crystal display device can be improved.

  The thickness of the retardation layer (B1) is preferably 5 μm or more, more preferably 7 μm or more, preferably 30 μm or less, more preferably 15 μm or less. By setting the thickness of the retardation layer (B1) within this range, the laminate can be thinned, and the laminate can be excellent in high temperature durability.

  The variation in thickness of the retardation layer (B1) is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less, of the average thickness of the layer (B1). By realizing such thickness accuracy, it is possible to obtain a laminate and a retardation film that exhibit uniform optical characteristics in the MD direction and the TD direction. Moreover, such thickness precision is realizable by manufacturing retardation film laminated body (B) with the manufacturing method which combined the melt extrusion and extending | stretching mentioned later, for example.

[4.3. Protective layer (B2)]
The protective layer (B2) can be formed of a resin. As this resin, a thermoplastic resin is usually used. Further, as this resin, a transparent resin is usually used. Examples of such resins include polymer resins having an alicyclic structure, (meth) acrylic resins, polycarbonate resins, (meth) acrylic acid ester-vinyl aromatic compound copolymer resins, and polyethersulfone resins. A resin selected from is preferred. These resins are excellent in mechanical strength, can have a desired peel strength with respect to the retardation layer (B1), and can reduce the retardation developed by stretching.

  As a polymer resin having an alicyclic structure capable of forming the protective layer (B2), a (meth) acrylic resin, a polycarbonate resin, a (meth) acrylic ester-vinyl aromatic compound copolymer resin, and a polyethersulfone resin For example, the same resins as those described as the material for forming the support can be used. Therefore, a polymer resin having an alicyclic structure capable of forming the protective layer (B2), a (meth) acrylic resin, a polycarbonate resin, a (meth) acrylic acid ester-vinyl aromatic compound copolymer resin, and a polyethersulfone In each of the resins, the types and amounts of the polymer and optional components that can be contained in the resin can be the same as those of the resins described as materials for forming the support.

  Among these resins, as the resin for forming the protective layer (B2), a polymer resin having a cycloaliphatic structure and a (meth) acrylic resin are preferable, and a (meth) acrylic resin is particularly preferable.

  The glass transition temperature of the resin forming the protective layer (B2) is preferably set according to the glass transition temperature of the non-liquid crystalline material having a negative intrinsic birefringence forming the layer (B1). Specifically, the glass transition temperature Tg (B1) of the non-liquid crystalline material having a negative intrinsic birefringence forming the layer (B1) and the glass transition temperature Tg (B2) of the resin forming the protective layer (B2) However, it is preferable to satisfy | fill Tg (B1)> Tg (B2) +20 degreeC, and it is more preferable to satisfy | fill Tg (B1)> Tg (B2) +25 degreeC. Thus, when the stretching treatment is performed at a stretching temperature higher than the glass transition temperature Tg (B1) of the non-liquid crystalline material having a negative intrinsic birefringence, the polymer is hardly oriented in the protective layer (B2), Become. Therefore, since a large retardation does not appear in the protective layer (B2) even by the stretching treatment, it is possible to accurately measure the retardation of only the retardation layer (B1) while performing the stretching treatment.

  Furthermore, the glass transition temperature of the polymer resin having an alicyclic structure capable of forming the protective layer (B2) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, preferably 150 ° C. or lower, more preferably Is 120 ° C. or lower, more preferably 110 ° C. or lower. By setting the glass transition temperature to be equal to or higher than the lower limit value of the above range, durability at high temperatures can be improved, and by setting the glass transition temperature to be equal to or lower than the upper limit value, stretching can be facilitated.

  In particular, the glass transition temperature of the (meth) acrylic resin capable of forming the protective layer (B2) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, preferably 120 ° C. or lower, more preferably 110 ° C. or lower. It is. By setting the glass transition temperature to be equal to or higher than the lower limit of the above range, blocking when the resin pellets are dried at a high temperature can be suppressed, so that mixing of moisture can be prevented. Moreover, since it can reduce the orientation of the (meth) acrylic polymer at the time of extending | stretching by setting it as an upper limit or less, it can suppress that a protective layer (B2) inhibits the optical function of a phase difference layer (B1).

  In particular, the glass transition temperature of the polycarbonate resin capable of forming the protective layer (B2) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, still more preferably 100 ° C. or higher, particularly preferably 120 ° C. or higher, preferably Is 160 ° C. or lower, more preferably 150 ° C. or lower. By setting the glass transition temperature to be equal to or higher than the lower limit value of the above range, durability at high temperatures can be improved, and by setting the glass transition temperature to be equal to or lower than the upper limit value, stretching can be facilitated.

  The protective layer (B2) has a retardation in the in-plane direction at a wavelength of 550 nm, preferably 30 nm or less, more preferably 20 nm or less, and particularly preferably 10 nm or less. By measuring the retardation of only the retardation layer (B1) while performing a stretching treatment when producing the retardation film laminate (B) by reducing the retardation in the in-plane direction of the protective layer (B2). Is possible.

  The thickness of the protective layer (B2) is preferably 1 μm or more, more preferably 3 μm or more, particularly preferably 5 μm or more, preferably 50 μm or less, more preferably 30 μm or less, and particularly preferably 15 μm or less. By setting the thickness of the protective layer (B2) to be equal to or greater than the lower limit of the above range, the mechanical strength of the protective layer (B2) can be sufficiently increased. Moreover, the softness | flexibility and handling property of a protective layer (B2) can be made favorable by setting it as an upper limit or less.

  The peeling force between the retardation layer (B1) having a negative intrinsic birefringence and the protective layer (B2) is preferably 0.5 N / 20 mm or less, more preferably 0.3 N / 20 mm or less, and particularly preferably 0.8. 15 N / 20 mm or less. The peeling force can be measured according to JIS K6855-2. By reducing the peeling force in this way, the protective layer (B2) can be peeled from the laminate, and the retardation film can be easily produced. The lower limit of the peeling force is preferably 0.01 N / 20 mm or more, more preferably 0.03 N / 20 mm or more, and particularly preferably 0.05 N / 20 mm or more. Such a small peeling force can be realized, for example, by appropriately selecting a combination of materials of the retardation layer (B1) and the protective layer (B2) with materials that are not compatible with each other.

[4.4. Adhesive layer]
The adhesive layer 401 constituting the composite retardation film 400 shown in FIG. 4 can be a layer formed of a cured product of an adhesive. Here, the adhesive includes a narrowly defined adhesive having a shear storage elastic modulus of 1 MPa to 500 MPa at 23 ° C. after curing, and a pressure-sensitive adhesive having a shear storage elastic modulus at 23 ° C. of less than 1 MPa. However, when the retardation film of the present invention containing the functional layer and the retardation film laminate (B) are bonded, if the bonding using the adhesive is performed, the entrapment of bubbles at the time of bonding and The thickness of the pressure-sensitive adhesive layer tends to increase in order to suppress the biting of foreign matter and to secure a strong adhesive force. On the other hand, in the bonding using a narrowly defined adhesive, the thickness of the adhesive layer can be reduced. Therefore, it is preferable to use a narrowly defined adhesive having a shear storage modulus of 1 MPa to 500 MPa at 23 ° C. after curing as the adhesive.

  As the adhesive, an active energy ray curable adhesive is usually used. The active energy ray-curable adhesive refers to an adhesive that can be cured when irradiated with active energy rays such as ultraviolet rays, X-rays, and electron beams. Among them, an adhesive that can be cured by ultraviolet rays is preferable because an inexpensive device can be used.

  As an example of a suitable adhesive, one containing (meth) acrylate in an uncured state can be used. Among them, as the (meth) acrylate, (I) an oligomer-type polyfunctional (meth) acrylate and (II) a mono (meta) having at least one hydroxyl group having a viscosity of 10 mPa · s or more and less than 500 mPa · s at a temperature of 20 ± 1.0 ° C. ) A combination of acrylates is preferred.

  Further, in the cured state or the uncured state, the adhesive may contain an optional component other than (meth) acrylate as long as the effects of the present invention are not significantly impaired. Optional components include, for example, a polymerization initiator, a crosslinking agent, an inorganic filler, a polymerization inhibitor, a color pigment, a dye, an antifoaming agent, a leveling agent, a dispersing agent, a light diffusing agent, a plasticizer, an antistatic agent, and a surface activity. Agents, non-reactive polymers (inert polymers), viscosity modifiers, near-infrared absorbers, and the like. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  Specific examples of the adhesive include those described in JP-A-7-82544.

  The thickness of the adhesive layer is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. By setting the thickness of the adhesive layer to be equal to or more than the lower limit of the above range, the adhesive force between the retardation film of the present invention including the functional layer and the retardation film laminate (B) can be increased. Moreover, by making it into the upper limit value or less, it becomes possible to increase the curing rate of the adhesive and to easily cure the adhesive, and to reduce the thickness.

[4.5. Example of production process of retardation film laminate (B)]
The retardation film laminate (B) produces a multilayer film (b) comprising a protective layer (B2), a retardation layer (B1) having a negative intrinsic birefringence, and a layer of material constituting the protective layer (B2). And it can manufacture by extending | stretching the multilayer film (b). The retardation layer (B1) having a negative intrinsic birefringence is generally weak in mechanical strength. However, by covering both sides of the retardation layer (B1) with protective layers (B2), the retardation layer (B1) at the time of stretching is covered. Damage can be reliably prevented. In addition, since the retardation layer (B1) can be sandwiched from both sides by the protective layer (B2) having high strength, bleeding out from the retardation layer (B1) can be effectively prevented. Here, the bleed out from the retardation layer (B1) refers to a phenomenon in which a part of components (for example, a compounding agent) contained in the retardation layer (B1) ooze out on the surface of the retardation layer (B1).

  An example of the manufacturing process of the retardation film laminate (B) is shown in FIG. FIG. 5 is a schematic view schematically showing an example of a production apparatus for producing the retardation film laminate (B). In FIG. 5, the manufacturing apparatus 500 includes a film forming unit 520 and a stretching unit 530.

  The film molding unit 520 is an apparatus for producing a multilayer film (b) including a protective layer (B2), a retardation layer (B1) having a negative intrinsic birefringence, and a layer of material constituting the protective layer (B2). . Examples of the production method include a coextrusion molding method; a film lamination molding method such as dry lamination; a co-casting method; and a coating molding method such as coating a resin solution on the resin film surface. Among these methods, the coextrusion molding method is preferable from the viewpoint of manufacturing efficiency and preventing a volatile component such as a solvent from remaining in the film.

  When employing the coextrusion molding method, the multilayer film (b) is obtained, for example, by coextruding a non-liquid crystalline material having a negative intrinsic birefringence and a resin forming the protective layer (B2). Examples of the co-extrusion molding method include a co-extrusion T-die method, a co-extrusion inflation method, and a co-extrusion lamination method, and among them, the co-extrusion T-die method is preferable. Further, the coextrusion T-die method includes a feed block method and a multi-manifold method, but the multi-manifold method is particularly preferable in that variation in thickness can be reduced. In the example shown in FIG. 5, the multilayer film (b) 390 before extending | stretching is manufactured by co-extruding material from the die | dye 521 on the cooling roll 522. FIG.

  The multilayer film (b) 390 continuously produced in the film forming unit 520 is conveyed to the stretching unit 530 and stretched. By stretching the multilayer film (b) 390, retardation is developed in the layer of the non-liquid crystalline material having a negative intrinsic birefringence, and a desired retardation film laminate (B) is obtained. Examples of the stretching performed in the stretching unit 530 include a method of uniaxial stretching in the MD direction using a difference in peripheral speed between rolls (longitudinal uniaxial stretching); uniaxial stretching in the TD direction using a tenter stretching machine. Method (lateral uniaxial stretching); method of performing longitudinal uniaxial stretching and transverse uniaxial stretching in order (sequential biaxial stretching); method of performing longitudinal uniaxial stretching and transverse uniaxial stretching simultaneously (simultaneous biaxial stretching); oblique to the MD direction A method of stretching in the direction (oblique stretching) can be employed. Here, “oblique direction” means a direction that is neither parallel nor orthogonal.

  By stretching in the stretching section 530, retardation is developed in the retardation layer (B1) having a negative intrinsic birefringence, and the retardation film composite 300 having desired optical characteristics is obtained. In the retardation film composite 300, the slow axis in the plane of the retardation layer (B1) having a negative intrinsic birefringence is usually perpendicular to the direction stretched by the stretching portion 530.

  Further, in this manufacturing method, steps other than those described above may be performed. For example, a preheat treatment may be performed on the multilayer film (b) 390.

  The obtained retardation film composite 300 is usually wound into a roll and stored. In the retardation film composite 300 obtained by such a manufacturing method, the mechanical strength of the retardation layer (B1) is low, but it is not easily damaged because it is protected by the protective layer (B2).

[4.6. Example of bonding process]
An example of a production method for producing the composite retardation film 400 shown in FIG. 4 using the retardation film of the present invention having a support and a functional layer and the retardation film laminate (B) is shown in FIG. . FIG. 6 is a schematic view schematically showing an example of a manufacturing apparatus used in the manufacturing method. In FIG. 6, the manufacturing apparatus 600 includes a peeling unit 610, a coating head 620, a bonding unit 630, and a curing processing unit 640.

  In operation, the retardation film laminate (B) 300 fed from the feeding device 601 is conveyed to the peeling unit 610. In the peeling part 610, one protective layer (B2) 302B is peeled from the fed retardation film laminate (B) 300. Thereby, one surface 301D of the retardation layer (B1) is exposed, and a retardation film laminate (B ′) 310 including the retardation layer (B1) and the protective layer (B2) is obtained.

  The retardation film laminate (B ′) 310 is conveyed to the coating head 620. The adhesive is applied to one surface 301 </ b> D of the retardation film laminate (B ′) 310 by the coating head 620.

  The retardation film laminate (B ′) 310 to which the adhesive has been applied is conveyed to the bonding unit 630. On the other hand, the retardation film laminate 100 having the support 111 and the functional layer 112 conveyed from the feeding device 603 is also conveyed to the bonding unit 630. In the bonding unit 630, the surface of the retardation film laminate (B ′) 310 to which the adhesive is applied and the surface 112 U on the functional layer 112 side of the retardation film laminate 100 are formed by the lami roll 631 and the counter roll 632. Bonded. The bonded film is further conveyed to the curing processing unit 640, and the adhesive is cured by an appropriate means such as irradiation with an active energy ray such as ultraviolet rays. Thereby, the composite phase difference film 400 which has the layer structure shown in FIG. 4 is manufactured. The obtained composite retardation film 400 can be wound up by a winding device 602 to form a roll, which can be subjected to further processes.

[5. Polarizer]
The polarizing plate of the present invention includes the retardation film of the present invention and a polarizer.
In a preferred embodiment, the polarizing plate of the present invention comprises the above-described composite retardation film and a polarizer.
An example of the polarizing plate of the present invention is shown in FIG. FIG. 7 schematically shows a cross section of an example of the polarizing plate of the present invention obtained by using the composite retardation film 400 and the polarizer shown in FIG. 4 taken along a plane perpendicular to the main surface. It is sectional drawing.

  In FIG. 7, a polarizing plate 700 includes a composite retardation film 410, a polarizer 702 and a protective layer 701 provided on one surface of the composite retardation film 410, and the other surface of the composite retardation film 410. An adhesive layer 703 and a separator 704 are provided.

  In the polarizing plate 700, the composite retardation film 410 is obtained by peeling the support 111 and the protective layer (B2) 302A from the composite retardation film 400 shown in FIG. The adhesive layer 401 and the retardation layer (B1) 301 are provided in this order.

  The polarizer 702 can be provided on the functional layer 112 side surface of the composite retardation film 410 by bonding to the functional layer 112 through an adhesive layer (not shown) as necessary. Examples of polarizers include, for example, a film of a suitable vinyl alcohol polymer such as polyvinyl alcohol and partially formalized polyvinyl alcohol, a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, a stretching treatment, and a crosslinking. The thing which performed appropriate processes, such as a process, in an appropriate order and system is mentioned. Such a polarizer is capable of transmitting linearly polarized light when natural light is incident thereon, and in particular, a polarizer excellent in light transmittance and degree of polarization is preferable. The thickness of the polarizer is generally 5 μm to 80 μm, but is not limited thereto.

  Any transparent film can be used as the protective layer 701. Among these, a resin film excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like is preferable. Examples of such resins include acetate resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and polymers having an alicyclic structure. Examples thereof include resins and acrylic resins. Among them, an acetate resin or a polymer resin having an alicyclic structure or an acrylic resin is preferable in terms of low birefringence, and an alicyclic structure from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. Particularly preferred are polymer resins having The thickness of the protective layer is preferably 500 μm or less, more preferably 300 μm or less, particularly preferably 150 μm or less, and usually 5 μm or more, from the viewpoint of thinning the polarizing plate.

  In the polarizing plate, the layers are usually arranged so that the in-plane slow axis of the retardation film and the transmission axis of the polarizer are parallel or orthogonal.

  The adhesive layer 703 is a layer provided for facilitating the operation of bonding the polarizing plate to another member, and the separator 704 is bonded before the polarizing plate is further bonded to another member. This is a layer for protecting the layer 703. As the adhesive layer 703, an arbitrary adhesive layer can be used. Examples of the adhesive include acrylic, silicone, polyester, polyurethane, polyether, rubber, and the like. Among these, an acrylic type is preferable from the viewpoint of heat resistance and transparency.

[6. LCD panel]
The liquid crystal panel of the present invention is an IPS liquid crystal panel including the polarizing plate of the present invention and a liquid crystal cell for IPS.
In a preferred embodiment, the liquid crystal panel of the present invention includes the above-described composite retardation film, a polarizing plate including a polarizer, and a liquid crystal cell for IPS.
An example of the liquid crystal panel of the present invention is shown in FIG. FIG. 8 schematically shows a cross section of an example of the liquid crystal panel of the present invention obtained by using the polarizing plate 700 and the liquid crystal cell for IPS shown in FIG. 7 cut along a plane perpendicular to the main surface. It is sectional drawing shown.

  In FIG. 8, the liquid crystal panel 800 includes a polarizing plate 710, an IPS cell 801 provided on the adhesive layer 703 of the polarizing plate 710, and another polarizing plate 802.

  In the liquid crystal panel 800, the polarizing plate 710 is formed by peeling the separator 703 from the polarizing plate 700 shown in FIG. 7, and accordingly, the protective layer 701, the polarizer 702, the stretched functional layer 112, the adhesive layer 401, A retardation layer (B1) 301 and an adhesive layer 703 are provided in this order.

  The IPS cell 801 can be provided by peeling the separator 703 from the polarizing plate 700 shown in FIG. 7 and then bringing one surface of the IPS cell 801 into contact with the adhesive layer 703. Before or after the contact, the polarizing plate 802 can be provided by bonding the polarizing plate 802 to the other surface of the IPS cell 801 through an adhesive layer (not shown) as necessary. The polarizing plate 802 may be composed of only the same layer as the polarizer 702, or may be composed of the same layer as the polarizer 702 and a protective layer, for example.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples described below, and does not depart from the scope of the claims of the present invention and the equivalents thereof. It may be carried out by arbitrarily changing in.
In the following description, “%” and “part” representing amounts are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and normal pressure conditions unless otherwise specified.

[Measuring method]
[Measurement method of retardation]
The surface of the multilayer film on the functional layer side is attached to the glass substrate via the adhesive layer, the support is peeled off, and a composite of the glass substrate / adhesive layer / functional layer is prepared as a sample. went. The retardation Re in the in-plane direction and the retardation Rth in the thickness direction of the functional layer are 5 in the vicinity of the center in the width direction of the film at a wavelength of 550 nm using an automatic birefringence meter (Oji Scientific Instruments “KOBRA-21ADH”). The point was measured and the average value was taken as the measured value.

[Measurement of residual solvent by gas chromatography]
(I) Preparation of sample Peel off the 5 cm x 5 cm rectangular functional layer, add to a vial (5 ml capacity), add 3 ml of acetone (made by Wako Pure Chemical Industries, Residual agricultural chemicals / PCB test), and at 80 ° C for 3 hours After heating, it was allowed to cool. The contents of the vial were stretched and separated at 1500 G for 3 minutes, and the solution (extract) was taken out.
(Ii) Preparation of standard solution A standard mother solution of the solvent used for preparing the solution was prepared, and a standard solution was prepared by appropriately diluting it.
(Iii) Preparation of Standard Addition Sample 0.5 ml of the standard mother liquid obtained in (ii) above was placed in a volumetric flask (20 ml capacity), and the volume was adjusted with acetone to obtain a preparation liquid.
The functional layer having a rectangular area of 5 cm × 5 cm was peeled off, taken into a vial (5 ml capacity), added with 3 ml of the preparation solution, heated at 80 ° C. for 3 hours, and then allowed to cool. The contents of the vial were stretched and separated at 1500 G for 3 minutes, and the solution (extract) was taken out.
(Iv) Measurement The gas chromatographic measurement was performed on the solution obtained in (i), the standard solution obtained in (ii), and the solution obtained in (iii). The measurement conditions are as follows.
Gas chromatography device: 6890 (Agilent Technologies)
Column: DB-5 (J & W) serial No. US7153041H, length 30m, inner diameter 0.25mm, film thickness 1.0μm
Inlet temperature: 100 ° C
Column flow: 3.0 ml / min
Carrier gas: He
Mode: Split Detection temperature: 150 ° C
Gas: H ₂ 40 ml / min, air 450 ml / min, N ₂ 50 ml / min
Column temperature 50 ℃ → 110 ℃
Temperature rising speed 20 ° C / min (linear gradient)

[Example 1]
(1-1. Preparation of solution)
Polycarbonate resin A (having a positive intrinsic birefringence value; “Iupizeta FPC-2136” manufactured by Mitsubishi Gas Chemical Company; glass transition temperature 132 ° C.) as a non-liquid crystalline material is mixed with cyclopentanone as a solvent, A solution having a solid concentration of 15% by weight was obtained.

(1-2. Formation of functional layer: production of multilayer film)
The functional layer was formed using the apparatus 200 schematically shown in FIG. 2 to produce a multilayer film schematically shown in FIG.
A long support 11 (“ZEONOR FILM” manufactured by Nippon Zeon Co., Ltd .; norbornene resin; thickness 80 μm; glass transition temperature 126 ° C.) is run from the feeding device 201 at a running speed of 10 m / min, (1-1) The solution obtained in (1) was applied using a die coater coating head 210 so that the dry film thickness was 17 μm. This formed the support body which has a coating film of a solution.
Immediately after coating, the support is conveyed to a dryer 220 having four chambers 220A to 220D, and drying steps (I) to (IV) are sequentially performed in each of the chambers 220A to 220D, thereby drying the solution. The solvent in the solution was removed to form a functional layer. Thereby, the elongate multilayer film 10 provided with the support body 11 and the functional layer 12 provided on it was obtained.

  In the step of removing the solvent, the conditions (temperature and wind speed) of the drying steps (I) to (IV) were as shown in Table 5. The wind speed in Table 5 is a value measured by an anemometer (trade name “Anemo Master”, model name 6162, manufactured by Nippon Kanomax Co., Ltd.). Each of the drying steps (I) to (IV) was performed for 30 seconds.

(1-3. Evaluation of functional layer)
The appearance of the functional layer on the multilayer film 10 carried out from the dryer 220 was observed, and the presence or absence of thickness unevenness, bubble streaks, and wrinkles based on the coating unevenness of the coating film was visually evaluated.
A part of the obtained multilayer film 10 was cut out, and the amount of residual solvent in the functional layer was measured by gas chromatography.

(1-4. Stretching of multilayer film: production of retardation film laminate)
The long multilayer film 10 obtained in (1-2) was stretched using a stretching apparatus 230 that is a tenter stretching machine. The stretching temperature was 140 ° C., the stretching direction was the TD direction, and the stretching ratio was 2.7 times. This obtained the retardation film laminated body 100 which has a layer structure of a support body / functional layer. The film thickness of the functional layer was 10 μm. In-plane retardation Re and thickness direction retardation Rth of the functional layer of the obtained retardation film laminate were measured. In addition, the adhesion between the film and the gripper and the presence or absence of curling during stretching were visually evaluated.

[Example 2]
The same procedure as in Example 1 was repeated except that 1,4-dioxane was used in place of cyclopentanone and the conditions of the drying process were changed as shown in Table 5. A retardation film laminate was produced and evaluated.

[Example 3]
(3-1. Preparation of solution)
Polycarbonate resin A (having a positive intrinsic birefringence value; “Iupizeta FPC-2136” manufactured by Mitsubishi Gas Chemical Co., Inc .; glass transition temperature 132 ° C.) as a non-liquid crystalline material, 1,4-dioxane and ethyl acetate as solvents And a mixed solvent (mixing ratio of 1,4-dioxane / ethyl acetate = 6/4 (weight ratio)) to obtain a solution having a solid concentration of 15% by weight.

(3-2. Formation of functional layer: production of multilayer film)
The functional layer was formed using the apparatus 200 schematically shown in FIG. 2 to produce a multilayer film schematically shown in FIG.
A long support 11 (“Zeonor film” manufactured by Nippon Zeon Co., Ltd .; norbornene-based resin; thickness 80 μm; glass transition temperature 126 ° C.) is run from the feeding device 201 at a running speed of 10 m / min, (3-1) The solution obtained in (1) was applied using a die coater coating head 210 so that the dry film thickness was 17 μm. This formed the support body which has a coating film of a solution.
Immediately after coating, the support is conveyed to a dryer 220 having four chambers 220A to 220D, and drying steps (I) to (IV) are sequentially performed in each of the chambers 220A to 220D, thereby drying the solution. The solvent in the solution was removed to form a functional layer. Thereby, the elongate multilayer film 10 provided with the support body 11 and the functional layer 12 provided on it was obtained.

  In the step of removing the solvent, the conditions (temperature and wind speed) of the drying steps (I) to (IV) were as shown in Table 5. The wind speed in Table 5 is a value measured by an anemometer (trade name “Anemo Master”, model name 6162, manufactured by Nippon Kanomax Co., Ltd.). Each of the drying steps (I) to (IV) was performed for 30 seconds.

(3-3. Evaluation of functional layer)
The appearance of the functional layer on the multilayer film 10 carried out from the dryer 220 was observed, and the presence or absence of thickness unevenness, bubble streaks, and wrinkles based on the coating unevenness of the coating film was visually evaluated.
A part of the obtained multilayer film 10 was cut out, and the amount of residual solvent in the functional layer was measured by gas chromatography.

(3-4. Stretching of multilayer film: production of retardation film laminate)
The long multilayer film 10 obtained in (3-2) was stretched using a stretching apparatus 230 that is a tenter stretching machine. The stretching temperature was 140 ° C., the stretching direction was the TD direction, and the stretching ratio was 2.7 times. This obtained the retardation film laminated body 100 which has a layer structure of a support body / functional layer. The film thickness of the functional layer was 10 μm. In-plane retardation Re and thickness direction retardation Rth of the functional layer of the obtained retardation film laminate were measured. In addition, the adhesion between the film and the gripper and the presence or absence of curling during stretching were visually evaluated.

[Example 4]
As a solvent, a mixed solvent of cyclopentanone and ethyl acetate (mixing ratio of cyclopentanone / ethyl acetate = 6/4 (weight ratio)) was used instead of the mixed solvent of 1,4-dioxane and ethyl acetate. A multilayer film and a retardation film laminate were produced and evaluated by the same operation as in Example 3 except that the conditions of the drying process were changed as shown in Table 5.

[Example 5]
As a solvent, instead of a mixed solvent of 1,4-dioxane and ethyl acetate, a mixed solvent of cyclopentanone and 1,4-dioxane (mixing ratio of cyclopentanone / 1,4-dioxane = 6/4 (weight) A multilayer film and a retardation film laminate were produced and evaluated by the same operation as in Example 3 except that the ratio)) was used and the drying process conditions were changed as shown in Table 5.

[Example 6]
As the non-liquid crystalline material, polycarbonate resin B (having a positive intrinsic birefringence value; “Iupizeta PCZ-200” manufactured by Mitsubishi Gas Chemical Company; glass transition temperature of 137 ° C.) was used instead of polycarbonate resin A. By the same operation as in Example 1, a multilayer film and a retardation film laminate were produced and evaluated.

[Example 7]
As the non-liquid crystalline material, bismaleimide resin (having a positive intrinsic birefringence value; “BMI 1500” manufactured by Air / Brown; glass transition temperature 90 ° C.) was used instead of polycarbonate resin A, and the drying process A multilayer film and a retardation film laminate were produced and evaluated in the same manner as in Example 1 except that the conditions were changed as shown in Table 6.

[Example 8]
A multilayer film and a retardation film laminate were produced and evaluated by the same operation as in Example 3 except that the conditions of the drying step were changed as shown in Table 6.

[Example 9]
A multilayer film and a retardation film laminate were produced and evaluated in the same manner as in Example 4 except that the conditions of the drying step were changed as shown in Table 6.

[Comparative Example 1]
Production of a multilayer film was attempted by the same operation as (1-1) to (1-2) of Example 1 except that ethyl acetate was used instead of cyclopentanone as the solvent. As a result, by applying the solution, the support was swollen and curved, and a multilayer film that could be used for the subsequent production of a retardation film laminate could not be obtained.

[Comparative Example 2]
As a solvent, instead of the mixed solvent of 1,4-dioxane and ethyl acetate, a mixed solvent of toluene and ethyl acetate (mixing ratio of toluene / ethyl acetate = 5/5 (weight ratio)) was used, and A multilayer film and a retardation film laminate were produced and evaluated in the same manner as in Example 3 except that the solid content concentration was 20% by weight.

[Comparative Example 3]
As a solvent, instead of a mixed solvent of 1,4-dioxane and ethyl acetate, a mixed solvent of cyclopentanone and 1,3-dioxolane (mixing ratio of cyclopentanone / 1,3-dioxolane = 6/4 ( A multilayer film and a retardation film laminate were produced and evaluated in the same manner as in Example 3 except that the weight ratio)) was used.

[Comparative Examples 4 and 5]
A multilayer film and a retardation film laminate were produced and evaluated by the same operation as in Comparative Example 3 except that the conditions of the drying step were changed as shown in Table 7.

  Tables 2 to 4 show data on the functional layer forming solutions used in the examples and comparative examples. The conditions of the drying process in an Example and a comparative example and the evaluation result about the obtained multilayer film are shown in Table 5-Table 7. In addition, Tables 8 to 10 show the stretching conditions performed in Examples and Comparative Examples and the evaluation results on the retardation film laminate.

* 1: Horizontal stripes (TD stripes) were observed.
* 2: More horizontal streaks were observed than * 1, and functional layer thickness unevenness due to solution application unevenness was observed.
* 3: More horizontal streaks were observed than * 1.
* 4: In stretching, adhesion between the gripper holding the film and the film occurred.
* 5: During stretching, the film was deformed by curling the portion gripped by the gripper.

[Consideration]
As is clear from the above results, in Examples 1 to 9 in which the solution used for forming the functional layer satisfies the requirements of the present invention, it is possible to form a functional layer with a better appearance as compared with the comparative example. In addition, smooth stretching without adhesion between the gripper and the film and occurrence of curling could be performed.

DESCRIPTION OF SYMBOLS 10: Multilayer film 11: Support body 12: Functional layer 100: Retardation film laminated body 111: Stretched support body 112: Stretched functional layer 200: Manufacturing apparatus 201: Feeding apparatus 202: Winding apparatus 210: Coating Work head 220: Dryers 220A to D: Chamber 230: Stretching device 300: Retardation film laminate (B)
301: Retardation layer (B1)
302A to B: protective layer (B2)
390: Multi-layer film (b) before stretching
400: Composite retardation film 401: Adhesive layer 410: Composite retardation film 500: Manufacturing apparatus 520: Film forming section 521: Die 522: Cooling roll 530: Stretching section 600: Manufacturing apparatus 601: Feeding apparatus 602: Winding apparatus 603 : Feeding device 610: Peeling part 620: Coating head 630: Bonding part 631: Lami roll 632: Counter roll 640: Curing treatment part 700: Polarizing plate 701: Protective layer 702: Polarizer 703: Adhesive layer 704: Separator 710: Polarizing plate 800: Liquid crystal panel 801: IPS cell 802: Polarizing plate

Claims (10)

A method for producing a multilayer film comprising a long transparent support, and a functional layer provided on the support,
A step of applying a solution containing a non-liquid crystalline material and two or more solvents onto the support to obtain a coating;
Removing the solvent from the coating film by drying to obtain the functional layer,
The solvent is a poor solvent for the support and a good solvent for the non-liquid crystalline material;
The solution contains two or more kinds of the solvents, each having a solubility parameter δ of 8.5 to 10.5 (cal / cm ³ ) ^1/2 and a solubility parameter difference Δδ of 0.5 to 1. .3 (cal / cm ^{3) 1/2} and difference ΔBp their boiling points Ri der 55 ° C. or less,
Removing the solvent comprises:
A drying step (I) for drying the coating film under a windless condition at a temperature of 15 to 25 ° C .;
A drying step of drying the coating film under a temperature of TD _(II) and a wind speed of 0.5 to 2.5 m / S, wherein the temperature TD _(II) is Bp _H −20 ° C. or less; A drying step (II) (where Bp _H is the boiling point of the highest boiling point among the solvents contained in the solution),
Obtained by removing the solvent, the thickness of the functional layer is Ru 5~30μm der,
A method for producing a multilayer film. The support is made of a resin having positive intrinsic birefringence,
The non-liquid crystalline material is a resin having positive intrinsic birefringence,
The method for producing a multilayer film according to claim 1 , wherein one or more of the solvents are ketones or ethers. The manufacturing method of the multilayer film of Claim 1 or 2 whose residual solvent amount in the said functional layer is 0.05-7 weight%. The non-liquid crystalline material is a polyimide resin, a maleimide resin, a polyamideimide resin, a polycarbonate resin, a polyester resin, polyurethane urea resin, and a resin selected from the group consisting of mixtures according to claim 1 any one of the three The manufacturing method of the multilayer film as described in a term. The manufacturing method of the multilayer film of any one of Claims 1-4 whose said support body is norbornene-type resin. The manufacturing method of the multilayer film of any one of Claims 1-5 whose peeling force between the said support body and the said functional layer is 0.05 N / 20mm or less. A method for producing a retardation film laminate comprising a step of stretching a multilayer film obtained by the production method according to any one of claims 1 to 6 ,
The step of stretching includes stretching by transverse stretching,
The stretching temperature in the stretching step is Tg _S ± 20 ° C. (where Tg _S is the glass transition temperature of the material constituting the support), and the stretching ratio is 1.01 to 3 times. A method for producing a retardation film laminate. The method for producing a retardation film laminate according to claim 7 , wherein the stretched functional layer has negative biaxiality. The manufacturing method of a polarizing plate including the process of providing a polarizer on one surface of the retardation film laminated body obtained by the manufacturing method of Claim 7 or 8 . The manufacturing method of the IPS liquid crystal panel which provides the polarizing plate obtained by the manufacturing method of Claim 9 on the surface of the liquid crystal cell for IPS.

Images