TW201710069A - Multi-layer laminated film - Google Patents

Abstract

Provided is a multi-layer laminated film formed by alternately laminating at least three layers of an A layer that comprises a crystalline resin a that can be oriented biaxially, and an B layer that comprises a resin b that has a crystallinity lower than that of a, the multi-layer laminated film being characterized in that when the phase difference in a k-th layer from a surface layer is expressed as Re(k) and the total number of layers is expressed as n, the total phase difference Re of the multi-layer laminated film satisfies formula (1) and formula (2). Provided is a film having a low phase difference, even if a resin is used which is a crystalline resin that can be oriented biaxially and has a high mechanical strength and is a resin having large birefringence. (2)Re<=400nm.

Description

Multilayer laminate film

The present invention relates to a multilayer laminated film and an optical film using the same.

A liquid crystal display device in which a liquid crystal display panel is a display element is used as a thin display device such as a liquid crystal television, a liquid crystal monitor, or a personal computer, and its use is rapidly expanding. In particular, the market for LCD TVs and mobile phones has expanded significantly.

A liquid crystal display device must use a polarizing plate, and a polarizing plate generally uses a polarizer to protect the film. From the viewpoint of high transparency and optical isotropicity, a film of triacetyl cellulose (hereinafter referred to as TAC) is widely used as a film thereof. . However, from the viewpoints of chemical resistance, scratch resistance, etc., it cannot be said that TAC film has exhibited sufficient performance, and with the development of large-scale and thinning of liquid crystal display in recent years, heat resistance, mechanical strength, and size Stability, high moisture permeability, and the like are problems.

In order to solve the above problems, other amorphous resins such as a cycloolefin polymer or acrylic acid have been studied in place of the TAC film (Patent Documents 1 and 2), but in many cases, almost no extension is imparted, and since a general-purpose resin is not used, It has the problem of high cost.

On the other hand, some people have studied the crystallinity such as polyester film. A resin is substituted for the TAC film (Patent Document 3). Among them, polyethylene terephthalate (hereinafter referred to as PET) film has lower moisture permeability and superior handleability than the TAC film, and it is a general-purpose resin and has an advantage of being cost-reducing, so it is often use. However, a film formed of a crystalline resin such as a PET film generally needs to be subjected to a treatment such as uniaxial stretching or biaxial stretching, and the phase difference may be increased by the stretching treatment. When the phase difference of the film is within a certain range, although it does not affect the visibility under natural light (non-polarized light), if it is viewed by a polarizer such as polarized sunglasses, it has a rainbow unevenness or an interference color. problem. On the other hand, in the non-extended state, it has the advantage of suppressing the generation of the light interference color, and on the other hand, it has a problem that the strength is remarkably lowered, and is not suitable for the protective film of the polarizing plate which has a demand for thinning in recent years.

Further, a retardation film which utilizes a multilayer structure and utilizes structural birefringence and molecular alignment birefringence has been proposed, and phase difference precision is required more than a polarizer protective film (Patent Document 4). However, in order to exhibit structural birefringence, the average layer thickness is extremely thinner than 30 nm, and a combination of a resin having a negative optical anisotropy and an amorphous resin of an isotropic amorphous resin, and a thickness and a total layer are combined. The number is also very large, so it has the problem of high material and manufacturing cost. That is, even if the optical properties are satisfied, the characteristics are the same as those of the conventional amorphous resin, and are not materials satisfying the film, low cost, low moisture permeability, and dimensional stability.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 6-51117

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2006-227090

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2013-200470

[Patent Document 4] Japanese Patent No. 4489145

The object of the present invention is to provide a film having a biaxially oriented A layer and a multi-layer laminated film having a relatively poor B layer, which is subtracted by the phase difference between the A layer and the B layer. When a film having a low phase difference is provided as a polarizer protective film on a display device such as a large-screen liquid crystal display, contrast, rainbow spot, and interference color are less changed, and a high-quality display can be obtained.

The inventors of the present invention conducted intensive studies and found that it is possible to optimize the combination of the resin and the film forming conditions when producing a film comprising a layer A comprising a biaxially oriented resin and a film having a relatively poor B layer. Then, the phase difference of the entire multilayered film becomes lower than the phase difference of the A layer and the B layer. Further, as a result of intensive studies, it has been found that in the multilayer laminated film, since the main alignment axes of the A layer and the B layer are different, the phase difference of the entire film is reduced, thereby completing the present invention.

That is, the present invention is as follows.

[1] A multilayer laminated film in which a layer A comprising a biaxially-oriented crystalline resin a and a layer B containing a resin b having a crystallinity lower than a are alternately laminated with at least three or more layers. The feature is that when the phase difference from the surface layer to the kth layer is Re(k) and the total number of layers is n, the total phase difference Re of the multilayer laminated film satisfies the formulas (1) and (2).

(2) Re≦400nm

[2] The multilayer laminated film according to [1], wherein the layer A comprising the biaxially-oriented crystalline resin a and the layer B containing the resin b having a lower crystallinity than the crystalline resin a are alternately laminated at least 3 The multilayer laminated film of the layer or more is characterized in that the refractive index in the direction of the maximum refractive index in the in-plane direction is Nx (1) and the refractive index in the direction perpendicular thereto is Ny on the outermost surface layer of the film. (1) When the total thickness of the layer body composed of the same resin as the outermost layer is d (A) and the total phase difference of the multilayer laminated film is Re, it satisfies the formula (5).

(5) Re-(Nx(1)-Ny(1))×d(A)<0

[3] Preferably, it is a multilayer laminated film, wherein the resin b contains a component selected from the group consisting of isophthalic acid, spiroglycerol, isosorbide, hydrazine, bisphenol A, and cyclohexane dimethanol. One of the ingredients in a group.

[4] Preferably, it is a multilayer laminated film in which the crystalline resin a is selected from any one of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate.

The invention has a low phase difference, so it can be used for a retardation film, a polarizer protective film having a phase difference function, and a substrate for a touch panel. Film and the like. Further, since the phase difference in the width direction is uneven or the misalignment angle is small, even when the polarizer protective film is mounted on a display device such as a liquid crystal display of a large screen, the following effects can be exhibited: contrast, rainbow spot or The change in the interference color is small, and a high-quality display can be obtained.

Fig. 1 is a schematic view showing the direction of light penetration when different resins are overlapped.

Fig. 2 is a schematic view showing the direction of light penetration when the same resin is overlapped.

Fig. 3(a) is a schematic view showing a case where two single film films are stacked. Fig. 3(b) is a schematic view showing the relationship between the refractive index ellipsoids when two single film films are stacked.

Fig. 4(a) shows the ellipsometric distribution of the refractive index in the width direction of the multilayer laminated film. (b) The refractive index ellipsoidal distribution of the multilayer laminated film in the width direction when two multilayer laminated films are stacked.

Fig. 5(a) is a schematic diagram showing phase difference subtraction using a single-layer multilayer film of full width. Fig. 5(b) is a schematic diagram showing the phase difference addition using a single-layer multilayer film of full width.

Fig. 6 is an alignment distribution of the A layer and the B layer of the multilayer laminated film of Example 11.

Fig. 7(a) shows the phase difference distribution in the film width direction in the multilayer laminated film of Example 13. Fig. 7(b) is an alignment angle distribution in the width direction of the film in the multilayer laminated film of Example 13.

Fig. 8(a) shows the MD direction of the multilayer laminated film of Example 13 The phase difference distribution in the width direction of the film when the two sheets were bonded was transferred. Fig. 8(b) shows the phase difference distribution in the film width direction when the MD directions of the multilayer laminated film of Example 13 are aligned and the two sheets are bonded together.

[Formation of the Invention]

The embodiments of the present invention are described below, but the present invention is not limited to the embodiments of the present invention, and various modifications may be made without departing from the spirit and scope of the invention.

Moreover, unless otherwise indicated, the in-plane phase difference of a film or a layer is a value represented by (Nx-Ny)*d. Here, Nx represents a refractive index perpendicular to the direction of the thickness direction of the film or layer (in-plane direction), that is, the direction in which the maximum refractive index is given. Ny represents the in-plane direction of the film or layer, that is, the refractive index perpendicular to the direction of the Nx direction. d represents the film thickness of the film or layer. Unless otherwise specified, the measurement wavelength of the above phase difference is 590 nm. The phase difference can be measured using a commercially available phase difference measuring device (for example, "KOBRA-21ADH" manufactured by Oji Scientific Instruments Co., Ltd., "WPA-micro" manufactured by Photonic Lattice Co., Ltd.) or a Senarmont method.

In the multilayer laminated film of the present invention, at least three or more layers of a film are laminated alternately between the crystalline resin a and the resin b. The term "interlayer" as used herein refers to a layer in which a layer containing different resins is laminated in a regular arrangement in the thickness direction. For example, in the case where the crystalline resin a and the resin b are contained, each layer is expressed as an A layer or a B layer. Then, the layer is layered by a regular arrangement such as A(BA)n (n is a natural number). Moreover, the outermost layer of the multilayer laminated film may also have a C layer comprising a resin c to form A composition such as C{A(BA)n}C. In the multilayer laminated film of the present invention, when the phase difference from the surface layer to the k-th layer is Re(k) and the total number of layers is n, the total phase difference Re of the multilayer laminated film satisfies the following formula (1). k is a natural number.

The above formula indicates that "the phase difference Re of the entire multilayered film obtained by using a commercially available measuring device" is smaller than the value obtained by adding the phase difference of each layer and adding the phase differences. Here, when measuring the phase difference of each layer, a film which peels each layer and becomes a single film can be measured by a commercially available measuring apparatus, and the surface layer can be grind|polished by the plastic abrasive cloth by the method of the Unexamined-Japanese-Patent No. 2014-149346. The measurement was performed after each layer was made into a single layer. The greater the subtraction effect of the phase difference, the stronger the display alignment is. From this point of view, the subtraction effect is preferably 50 nm or more. More preferably, it is 100 nm or more.

In the case where the film is formed by sequential biaxial or uniaxial stretching under the same film forming conditions, the crystallinity of the resin is higher, and the in-plane retardation is larger. Therefore, the phase of the film when the crystalline resin a is used is used. When the difference is Re (a) and the phase difference of the film when the crystallinity is lower than the resin b of the resin a is Re(b), then (8) Re(a)>Re(b)

The above formula (8) is established. Therefore, when it is difficult to measure the phase difference of the inner layer resin of the multilayer laminated film, the above formula can be simplified to the mathematical expression shown below.

Here, Re(1) is the phase difference of the outermost surface layer of the multilayer laminated film, and Nx(1) and Ny(1) are the refractive indices respectively giving the direction of the maximum refractive index of the outermost layer in the planar direction and perpendicular thereto. The refractive index in the direction, d(1) is the thickness of the outermost layer, and D' is the total thickness of the layer of the same resin as the outermost layer in the multilayer laminated film. Next, the equation will be described. The refractive index in the in-plane direction of the outermost layer can be obtained by using an elliptical spectral polarizer, a spectrophotometer, a krypton coupler, an Abbe refractometer or the like. Next, since the thickness can be measured by using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), the phase difference of the outermost layer can be easily calculated. When the resin of the inner layer and the outermost layer are the same resin, if the film forming conditions are the same, it is assumed that the outermost layer and the inner layer have the same birefringence, and the phase difference of the inner layer can be estimated. Therefore, the phase difference can be measured for the case where the outermost layer of the multilayer laminated film is the same resin. Here, if the layered body composed of the same resin as the outermost layer has a phase difference addition value larger than the total phase difference Re of the multilayer laminated film, the formula (1) of the claim 1 is satisfied. That is, it shows the phase difference of the layer of the resin different from the outermost layer, and the effect of the phase difference subtraction is exerted on the multilayer laminated film.

Here, the phase difference subtraction effect of the multilayer laminated film will be described. In the two-layer film described in FIG. 1 , the refractive indices in the in-plane direction of the A layer are Nx (a), Ny (a), and the refractive indices in the in-plane direction of the B layer are respectively Nx (b). ), Ny(b), then the birefringence of layer A is (Nx(a)-Ny(a)) and the birefringence of the B layer are (Nx(b)-Ny(b)), so the total phase difference Re of the two-layer film described in Fig. 1 is: Re=( Nx(a)-Ny(a))×d(a)+(Nx(b)-Ny(b))×d(b)

At this time, if the B layer and the A layer are the same resin, assuming that the layer is A', as shown in Fig. 2, Nx(a) = Nx(a'), Ny(a) = Ny(a') Therefore, Re=(Nx(a)-Ny(a))×d(a)+(Nx(a')-Ny(a'))×d(a')=(Nx(a)-Ny( a)) × (d(a) + d(a')) = (Nx(a) - Ny(a)) × d

This is the same result as calculating the phase difference of the A-layer single film. Here, d represents the thickness of the two-layer film. Therefore, the total phase difference Re of the multilayer laminated film is apparently the added value of the phase difference of each film. Therefore, in general, the phase difference between the refractive index and the thickness of each layer and the laminated film measured using a commercially available measuring device should be the same value.

On the other hand, in the present invention, the crystalline resin a and the resin b having a lower crystallinity are used, and the film forming conditions are further studied, whereby the "total phase difference Re of the multilayer laminated film" is successfully compared with the "phase of each layer". The difference between the added values is further reduced. The following is a detailed description of the mechanism, which differs from the main alignment axes of the layers.

(2) Re≦400nm

Further, as shown in the formula (2), the overall phase difference Re of the multilayer laminated film, that is, the phase difference in the in-plane direction must be 400 nm or less. By conforming to this condition, it is easy to obtain a multi-layer laminated film having the following characteristics: even when viewed through a polarizing plate such as sunglasses, it is not easy to see. The interference color was measured. The interference color under crossed Nichol is related to the phase difference, which is known from the Michel-Levy chart. In the case of "observation of the crossed nibble under the vertical relationship of the polarizer", it is more preferably 200 nm or less from the viewpoint of colorlessness. More preferably, it is 100 nm or less. The method of achieving this is an in-depth study of the following resin composition and film forming conditions.

In the outermost surface layer of the multilayer laminated film of the present invention, the refractive index in the direction in which the maximum refractive index in the in-plane direction is given is Nx (1), and the refractive index in the direction perpendicular thereto is Ny (1). When the total thickness of the layer body composed of the resin having the same outermost layer is d (A) and the total phase difference of the multilayer laminated film is Re, it is preferable to satisfy the formula (5).

(5) Re-(Nx(1)-Ny(1))×d(A)<0

From the viewpoint of further reducing the phase difference, the left side of the formula (5) is more preferably -50 nm or less. It is preferably -100 nm or less. The best is below -150 nm. In order to increase the effect of the subtraction, from the viewpoint of aligning the layer B which is more difficult to align with the layer A, the stacking ratio, that is, the total thickness of the layer A/the thickness of the layer B is preferably 1 or less. More preferably 0.7 or less. Further, the glass transition temperature of the resin b used for the layer B is preferably 88 ° C or higher.

In the multilayer laminated film of the present invention, it is necessary to use a biaxially-oriented crystalline resin a and a resin b having a lower crystallinity than a. The resin which can be biaxially aligned refers to a resin having a refractive index in the in-plane direction higher than a refractive index in the thickness direction when extending in the longitudinal direction and the width direction of the film. The measurement can be easily performed using an optical measuring device such as a 稜鏡 coupler. Further, the crystalline resin is a resin having a glass transition temperature Tg and a melting point Tm, and is a resin having a melting enthalpy change amount ΔHm>0. The ΔHm of the crystalline resin is preferably 10J/g or more. More preferably 20J/g. Further, the resin b must have a lower crystallinity than the crystalline resin a, and it may contain an amorphous resin. When the crystallinity of the crystalline resin a and the resin b are different, the main alignment axes of the A layer and the B layer in the multilayer laminated film can be changed in accordance with the film forming conditions suitable for the resin. As a method of evaluating crystallinity, it is known that the ΔHm size measured by DSC can be evaluated. The larger the ΔHm, the larger the energy consumed for melting, so the higher the crystallinity. Therefore, ΔHm of the crystalline resin a must be higher than ΔHm of the resin b. That is, the relationship of ΔHm(a)>ΔHm(b) holds. Further, the resin b may be an adhesive having an adhesive property, an adhesive, and a curable resin.

Moreover, it is preferable that the difference in glass transition temperature between the crystalline resin a and the resin b is large. It is particularly preferable that the glass transition temperature of the crystalline resin a is lower than the glass transition temperature of the resin b. This point is described in the following paragraph, whereas in the present invention, a sequential biaxial extension is employed, and lateral extension is performed after longitudinal extension. Generally, if the temperature of the longitudinal extension is sufficiently higher than the glass transition temperature, the longitudinal alignment in the longitudinal extension cannot be performed. For example, in the case where the glass transition temperature of the resin b is higher than the glass transition temperature of the crystalline resin a and the glass transition temperature of the resin b is +5 ° C, the layer A cannot be aligned, and the other layer On the other hand, the longitudinal alignment of the B layer becomes stronger than that of the A layer. Then, by performing the lateral stretching at a temperature higher than the longitudinal stretching temperature and then performing the heat treatment, since the layer A is crystalline, it is aligned and crystallized in the width direction, followed by thermal crystallization, and on the other hand, the layer B is easy. Residual longitudinal alignment. As a result, the main alignment axes of the A layer and the B layer can be deviated. Therefore, the difference in glass transition temperature is preferably a difference of 5 ° C or more. On the other hand, if the difference in glass transition temperature is too large, it cannot be uniformly extended, resulting in poor thickness uniformity, and thus the phase difference relative to the longitudinal It becomes uneven in the direction of the width and width. Therefore, the difference in glass transition temperature is preferably 40 ° C or less.

As the crystalline resin a used in the multilayer laminated film of the present invention and the resin b having a lower crystallinity, specifically, polyethylene, polypropylene, poly(4-methylpentene-1), polycondensation can be used. Polyolefin such as aldehyde, ring opening metathesis polymerization as a cycloolefin, addition polymerization, aliphatic polyolefin with addition copolymer of other olefins, polylactic acid. Biodegradable polymer such as polybutyl succinate, polyamine, nylon armid, polymethyl methacrylate, polyvinyl chloride, polypredator, etc. of nylon 6, 11, 12, 66, etc. Vinyl chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymerized polymethyl methacrylate, polycarbonate, polyparaphenylene Polyesters such as propylene glycol dicarboxylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalene dicarboxylic acid, polyether oxime, polyether ketone, modified polyphenylene Ether, polyphenylene sulfide, polyether phthalimide, polyimide, polyarylate, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, acrylonitrile. Butadiene. Styrene copolymerized copolymer and the like. Among them, polymethyl methacrylate, polycarbonate, and polyester are preferably used from the viewpoint of strength, transparency, and versatility. Particularly good for polyester. The resins may be homopolymers, copolymerized polymers, or even mixtures of thermoplastic resins. Further, various additives such as an antioxidant, an antistatic agent, a nucleating agent, inorganic particles, organic particles, a viscosity reducing agent, a heat stabilizer, a slip agent, an infrared absorbing agent, and an ultraviolet absorber may be added to each thermoplastic resin. A dopant or the like for adjusting the refractive index.

The polyester is preferably a polyester obtained by polymerizing a monomer having an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as a main constituent component. Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, and 2,6-. Naphthalene dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylstilbene dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and the like. Examples of the aliphatic dicarboxylic acid include adipic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexane dicarboxylic acid, and ester derivatives of the acids. Among them, it is preferred to use terephthalic acid and 2,6-naphthalenedicarboxylic acid which exhibit a high refractive index. These acid components may be used alone or in combination of two or more. Even the oxy acid of hydroxybenzoic acid may be partially copolymerized.

Further, examples of the glycol component include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, neopentyl glycol, 1,3-butylene glycol, and 1,4-butanediol. 5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, three Ethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbate, spiroglycerol, and the like. Among them, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

Among the above polyesters, polyethylene terephthalate and copolymers thereof, polyethylene naphthalate and copolymers thereof, polybutylene terephthalate and copolymers thereof, and polynaphthalene are preferably used. The butylene dicarboxylate and its copolymer are preferably made of poly(trimethylene terephthalate) and its copolymer, poly(cyclohexanedimethylene terephthalate) and copolymers thereof.

The preferred resin combination of the present invention, as a biaxially-oriented crystalline resin a, comprises polyethylene terephthalate or polyethylene naphthalate Any one of a diester and a polybutylene terephthalate, and a resin b having a crystallinity lower than that of the crystalline resin a, is preferably a copolymer of the crystalline resin a. The resin b is preferably a copolymer having one or more components selected from the group consisting of isophthalic acid, spiroglycerol, isosorbate, hydrazine, bisphenol A, and cyclohexane dimethanol. Polyester. For example, it is preferred to use ethylene terephthalate copolymerized polyethylene terephthalate, spiro glycerol copolymerized polyethylene terephthalate, isosorbide copolymerized polyethylene terephthalate, hydrazine A resin obtained by copolymerizing polyethylene terephthalate, bisphenol A copolymerized polyethylene terephthalate or polybutylene terephthalate. The copolymerization component is preferably 5 mol% or more and 50 mol% or less from the viewpoint of the layering property with the crystalline resin a and the effect of the phase difference. If it is less than 5 mol%, it is easy to exhibit an additive effect. On the other hand, if it is 50 mol% or more, there is a possibility that the subtraction effect cannot be intervened. From the viewpoint of making the total phase difference Re of the multilayer laminated film 400 m or less, it is more preferably 10 mol% or more and 40 mol% or less.

The glass transition temperature of the crystalline resin a of the present invention is preferably lower than the glass transition temperature of the resin b. In the film forming step of the successive biaxially stretched film, the layer B containing the resin b is aligned in the longitudinal direction by setting the longitudinal stretching temperature above the glass transfer of the resin b, but the layer A containing the resin a is not in the longitudinal direction. Matching. Then, when laterally extending at a temperature higher than the longitudinal extension temperature, the layer A containing the resin a tends to be aligned in the lateral direction, and on the other hand, the layer B containing the resin b remains in the longitudinal alignment state, and is guided. Heat treatment step. Thus, the layer A is subjected to alignment crystallization in the lateral direction. Moreover, this is because the bowing phenomenon is increased, and the cross-alignment of the main alignment axes of the A layer and the B layer is realized. State, and the phase subtraction effect is easy to occur. The glass transition temperature of the resin b is preferably 10 ° C or more higher than the resin a, and more preferably 20 ° C or higher. For example, when the resin a is polyethylene terephthalate, the glass transition temperature is around 78 ° C, so the glass transition temperature of the resin b is preferably 88 ° C or higher. More preferably, it is 90 or more, and further preferably 95 or more.

Next, a preferred method of producing the film of the present invention will be described.

First, crystalline resin a and resin b in the form of particles or the like are prepared. The granules may be dried in hot air or under vacuum according to demand, and supplied to each extruder. In the extruder, the resin is melted to a temperature equal to or higher than the melting point, and the amount of extrusion of the resin is made uniform by a gear pump or the like, and foreign matter, a modified resin, or the like is removed by a filter or the like.

The crystalline resin a and the resin b which are sent from the different channels using two or more extruders are then fed to a multilayer laminating apparatus. As the multilayer laminating apparatus, a multi-flow type mold, a feed block, a static mixer, or the like can be used. Further, the devices may be arbitrarily combined. Among them, in order to obtain the effect of the present invention efficiently, it is preferable to use a multi-flow split mold or a feeding tool which can individually control the thickness of each layer. The structure of the feeding device has at least one member on a comb slit plate having a large number of fine slits, and the crystalline resin a and the resin b supplied from the two extruders are introduced into the slit via the respective split portions. board. Here, the crystalline resin a and the resin b flow in through the introduction plate, so that a multilayer structure such as A/B/A/B/·· can be finally formed. Also, the number of layers can be increased by overlapping the slit plates. Further, the thickness of the layer body can be controlled by adjusting the slit shape (length, gap). Alternatively, a third other extruder can be used in the multi-layer laminate The outermost layer of the film is provided with a C layer comprising a resin c. For the above-mentioned methods, the method of manufacturing the multilayered laminated film and the multilayered laminated film is described in detail in Japanese Laid-Open Patent Publication No. 2007-307893 and JP-A-2007-79349. From the viewpoint of adding functions such as "phase difference control" and "light interference reflection due to layers of light wavelength levels", the number of layers is preferably nine or more. More preferably 50 layers or more, and even more preferably 200 layers or more. When the number of layers is too large, stacking disorder such as flow marks is likely to occur, and from this viewpoint, it is preferably 600 or less. Further, the average layer thickness is preferably from 0.04 to 10 μm. If it is less than 0.04 μ, the optical properties of each layer and the properties of the material are lost, which is not preferable. On the other hand, if it exceeds 10 μm, the thickness of the film becomes too thick, which is not preferable. From the viewpoint of imparting transparency to ultraviolet light and maintaining transparency, it is preferably 0.04 to 0.06 μm or 0.11 to 5 μm.

It is preferable to extrude a multi-layered melt in this manner from a slit-like mold into a sheet shape, and to adhere it to a casting drum by applying static electricity or the like, and to perform cooling solidification to form an unstretched sheet. , extending and heat treatment in two directions. Further, in order to impart a function such as mobility (slipiness), weather resistance, and heat resistance to the film, particles may be added to the film material, but it is necessary to pay sufficient attention to the amount and material to avoid the high transparency of the film. The amount of addition is preferably a very small amount, and preferably no addition. As for the mobility (slipperiness) of the film, as described above, it is preferred to assist with the additional particles of the adhesion layer. As the material of the particles added to the raw material of the film, for example, a heat-resistant stabilizer, an antioxidant stabilizer, a weathering stabilizer, an ultraviolet absorber, and a slip agent can be used, and the polyimide can be used, and the polyimide can be used. Methyl acrylate, formaldehyde resin, phenol Organic fine particles such as aldehyde resin and crosslinked polystyrene; wet and dry ceria, colloidal cerium oxide, aluminum citrate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin can also be used. Inorganic fine particles such as clay.

Preferably, the laminated film obtained in this manner is subjected to simultaneous biaxial, sequential biaxial, oblique stretching, and heat treatment. Here, the biaxial stretching means extending in the longitudinal direction (longitudinal direction) and the width direction (lateral direction). In the present invention, the main alignment axes of the A layer and the B layer must be deviated, so that the extension is preferably performed successively in two directions. Further, it is also possible to perform re-expansion in the longitudinal direction and/or the width direction after the biaxial stretching.

The description will be made for the sequential biaxial extension. Here, the extension in the longitudinal direction refers to the extension of the molecular alignment for imparting the longitudinal direction of the film, which is generally performed by the circumferential rate difference of the roller, and the extension can be performed in one stage, and It is also possible to use a plurality of rollers for multiple stages. The magnification of the stretching varies depending on the type of the resin, and is generally preferably 2 to 15 times. When PET is used for any of the resins constituting the multilayer laminated film, it is particularly preferably used 2 to 7 times. Further, the stretching temperature is preferably a glass transition temperature to a glass transition temperature of the resin constituting the multilayer laminated film + 100 °C. Here, in particular, in the laminated film of the present invention, it is preferred that the alignment of any of the crystalline resin a or the resin b in the longitudinal direction is strong. In order to enhance the alignment, the preferred extension conditions are extended from a glass transition temperature of -10 ° C to +10 ° C. Therefore, if the glass transition temperature of the resin b is high, the glass transition temperature of the resin b is preferably ±10. 2.8 to 3.7 times extension within °C. Further preferably, it is extended by 3.3 to 3.7 times within a glass transition temperature of the resin b + 10 ° C.

After the uniaxially stretched film obtained in this manner is subjected to surface treatment such as corona treatment, flame treatment, plasma treatment, etc., it can be imparted with smoothness by in-line coating, Easy adhesion, antistatic properties and other functions.

Further, the extension in the width direction means an extension for imparting an alignment in the width direction of the film, and a tenter method is generally used. This is carried out while grasping both ends of the film with a jig and extending in the width direction. The magnification of the stretching varies depending on the type of the resin, but is generally preferably 2 to 15 times. In the case where PET is used as the resin constituting the multilayer laminated film, it is particularly preferably used 2 to 7 times. Further, the stretching temperature is preferably a glass transition temperature to a glass transition temperature of the resin constituting the multilayer laminated film + 120 °C.

Here, in particular, in the multilayer laminated film of the present invention, in order to suppress the phase difference in the film width direction and to improve the phase difference and the alignment angle uniformity in the film width direction, it is preferred to adopt the following method: in the film width direction In the case of stretching, a method of gradually increasing the elongation temperature from a low temperature to a high temperature; a method of stretching at a high stretching ratio after stretching in the film width direction, and then extending at a low stretching ratio. One of the causes of the decrease in the uniformity of the phase difference and the width direction of the alignment angle is often the extension stress acting on the flow direction of the film when extending in the width direction. Here, by extending the film in the film width direction by the above method, the stress generated in the film flow direction can be controlled, and the stress in the film width direction can be relatively increased, so that the phase difference in the film width direction can be achieved. High angle uniformity. In the present invention, it is preferred to carry out a 3.3 to 4.6-fold extension at a lateral stretching temperature of 100 ° C or higher.

The total phase difference Re is dependent on the aspect ratio of the vertical and horizontal directions, so the ratio of the longitudinal stretching ratio/lateral stretching ratio is preferably close to 1. In order to make the total phase difference Re to be 400 nm or less, the ratio is preferably 0.6 or more, and more preferably 0.7 or more.

In order to impart planarity and dimensional stability to the film which is biaxially stretched in this manner, it is preferred to carry out heat treatment at a temperature equal to or higher than the melting point in the tenter. By performing heat treatment to thermally crystallize it, thermal dimensional stability is improved. After the heat treatment in this manner, the mixture was uniformly cooled slowly, and then cooled to room temperature and wound. Further, it is also possible to use a relaxation treatment or the like in combination with slow cooling from the heat treatment according to the demand.

In the multilayered film of the present invention, in order to suppress the unevenness of the phase difference in the width direction of the film, it is preferred to carry out heat treatment after temporarily stretching in the film width direction and then temporarily cooling to a temperature below the glass transition temperature. In this case, by cooling to a temperature lower than the glass transition temperature, the elongation stress in the film flow direction in the extending step in the film width direction can be controlled, and as a result, the phase difference uniformity in the film width direction can be improved.

Further, in the multilayer laminated film of the present invention, it is preferred to increase the temperature during the heat treatment stepwise. When the temperature at the end of the extension in the film width direction is T1, the temperature at the start of the heat treatment is T2, and the maximum temperature of the heat treatment step is T3, it is more preferable that T2 is T1 + 10 ° C or more and T3. Below -10 ° C, it is better that T 2 is in the range of (T1 + T3) / 2 ± 10 ° C. Thus, even if the heat treatment temperature is raised stepwise, the elongation stress in the film flow direction in the stretching step in the film width direction can be controlled, and as a result, the phase in the film width direction can be improved. Uniformity of the difference. Further, in the multilayer laminated film of the present invention, in the heat treatment step, it is preferred to extend the film width after the end of the stretching step in the film width direction by 1.01 times or more and 1.2 times or less. In the heat treatment step, stress is hardly generated in the longitudinal direction of the film, so that the phase difference in the width direction and the uniformity of the alignment angle can be improved. On the other hand, in the case where the stretching ratio in the film width direction is more than 1.2 times in the heat treatment step, the film has uneven thickness, and conversely, the phase difference is deteriorated. The thickness of the obtained multilayer laminated film is preferably 30 μm or less from the viewpoint of film formation. More preferably, it is 20 μm or less. Further preferably 15 μm or less.

The multi-layer laminated film of the present invention is a multilayer laminated film in which the main alignment axis has an inclination of 10 to 80° with respect to the width direction, and the angle formed by the main alignment axis of the A layer included in the multilayer laminated film and the main alignment axis of the B layer. It is preferably 60 to 120°. The main alignment axis indicates the orientation in which the refractive index is the highest in the in-plane refractive index, and is sometimes referred to as the alignment angle with respect to the reference line. The inclination of the main alignment axis here is an absolute value. The measurement method of the alignment angle is that only the total phase difference Re can be measured in the KOBRA-21ADH. The 稜鏡 coupler can only directly determine the refractive index of the outermost layer. On the other hand, by measuring with the FT-IR polarized ATR method, the alignment parameters can be used to directly measure the main alignment axes of the respective layers. Detailed description will be given next. As an alignment parameter, polyethylene terephthalate or isophthalic acid copolymerized polyethylene terephthalate can be detected by 1340 cm-1 in the in-plane orientation of 15° (CH ₂ longitudinal rocking vibration: anti The ratio of the peak intensity of the formula /1410 cm-1 (aromatic ring: C=C stretching vibration) to the peak intensity is obtained, and the main alignment axis is obtained. Next, the isosorbide copolymerized polyethylene terephthalate system can use a peak characteristic of isosorbide, that is, a peak intensity of 1097 cm-1 / a peak intensity of 1410 cm-1 as an alignment parameter, on the other hand, The glycerol-glycolized polyethylene terephthalate system uses a ratio of the peak intensity of 1165 cm-1/peak intensity of 1410 cm-1 as an alignment parameter, and detects the in-plane orientation to determine the main alignment axis. . When the angle formed by the main alignment axis of the layer A included in the multilayer laminated film and the main alignment axis of the layer B is less than 60° or more than 120°, the phase difference subtraction effect is less, so it is preferably 70° to 110°. °. More preferably 80°~100°. Further, the method of independently determining the alignment parameters of the A layer and the B layer can be measured by dry grinding in the thickness direction.

Further, in the multilayer laminated film of the present invention, the phase difference in the film width direction is preferably 50 nm/200 mm or less. If the phase difference is less than 50 nm/200 mm, color spots may occur when used as a polarizer protective film in display applications. More preferably, it is 30 nm / 200 mm or less.

The multilayer laminated film of the present invention preferably has a reflectance at a wavelength of 350 nm of 20% or more. This is because, in the use of the polarizing plate, in order to prevent photodegradation of the polarizer, the polarizer protective film is required to have a function of isolating UV. Further, in the C layer including the liquid crystal material described below, the hardening reaction by radical polymerization by light mainly uses light in the vicinity of the I line having a wavelength of 365 nm. When the multilayer laminated film itself reflects ultraviolet rays, the ultraviolet light applied to the photoreaction is not reflected back to the original portion from the bottom surface of the coating film, and is irradiated again to the coating film. Therefore, the speed at which the liquid crystal material of the C layer is light-aligned is increased, and the photo-alignment film which achieves the desired anisotropy is easily formed. The reflectance is more preferably 30% or more. More preferably 50% or more.

The aggregate multilayer film of the present invention comprises an A layer comprising a crystalline resin a and a B layer comprising a resin b having a lower crystallinity than the crystalline resin a. The first multilayer laminated film and the second multilayer laminated film in which at least two or more layers are laminated are sequentially superposed on the aggregate of the kth multilayer laminated film. When the phase difference of the multilayer laminated film in the k-th layer is Re (k) and the number of all the multilayer laminated films is n, the total phase difference SRe which is an aggregate of the multilayer laminated film must satisfy the following formula (3) ). k is a natural number.

By satisfying the above formula, it is shown that when the plurality of multilayer laminated films are superposed, the subtraction effect of the phase difference is exhibited in the integrated multilayer laminated film. From the viewpoint of suppressing interference color or rainbow spot, SRe is preferably a phase difference of 400 nm or less. More preferably, it is 250 nm or less. From the viewpoint of exhibiting the subtraction effect of the phase difference, the natural number n of the number of sheets of the superposed multilayer laminated film is 2 or more. Further, it is preferably a multiple of two. When the layers are alternately laminated so that the main alignment axes of the respective multilayer laminated films are perpendicular to each other, the phase difference is easily subtracted. Adhesives, adhesives or air may also be present between the laminates of the multilayer laminated films. These components may contain various additives such as an ultraviolet absorber, a pigment, and a light stabilizer. Further, it is also possible to carry out processing of a metal or a metal oxide which is obtained by vapor deposition or the like, which is almost independent of the phase difference. The multi-layer laminated film which is overlapped may have different sampling positions in the width direction of the multilayer laminated film obtained by the same film forming process. Alternatively, it may be a multilayer laminated film having a different resin composition.

Next, in the multilayer laminated film in which the unevenness of the phase difference or the unevenness of the alignment angle is large due to the arcuate tortuosity phenomenon, the low phase is realized in the entire width direction of the film by the overlapping of the multilayer laminated film. The method of achieving the difference is explained. Here, the arcuate tortuosity refers to the following film deformation behavior: in the manufacturing method of the sequential biaxially stretched film, the marking ink straight drawn in the film width direction before the tenter is turned at the tenter exit. The position of the tenter clip is a fixed arc curve. The mechanism occurs because in the lateral extension, according to the contraction stress of the Poisson's ratio, it acts in the opposite direction to the direction of travel, and the film of the heat-fixed region is pulled into the extended region.

The subtraction effect of the phase difference will be described in detail using Fig. 4, based on the refractive index ellipsoid distribution in the film width direction when the multilayer laminated film of the present invention is produced. Fig. 4(a) shows the ellipsometric distribution of the refractive index in the width direction of the multilayer laminated film. It is an ellipsometric distribution of the refractive index in the width direction of the film which is cut from the full width sample of the multilayer laminated film. The C position indicates the central portion in the film width direction. In the film formation by the sequential biaxial stretching, the arcuate phenomenon is obtained, and the birefringence (phase difference) is increased in the end portion in the film width direction, and the inclination (alignment angle) of the main alignment axis is also And become bigger. 2W indicates the size of the film width. The direction of the arrow of MD (Machine Direction) indicates the direction in which the film travels. 2W is dependent on the size of the manufacturing device, and is generally 0.5 to 2 m or more. Here, the alignment angle and the phase difference are the alignment angles and phase differences of the respective layers in the film thickness direction which can be measured by KOBRA. Next, Fig. 4(b) shows the refractive index ellipsoidal distribution of the multilayer laminated film in the width direction when two multilayer laminated films are stacked. The same multilayer laminated film cut from different positions in the longitudinal direction is an ellipsoidal distribution of the refractive index of the multilayer laminated film of two full widths in which the traveling direction is reversed by 180°. Except for the central part, we can see that two layers of thin layers are thin. The refractive index of the film is ellipsoidal. As a result, the subtraction effect of the phase difference is exhibited, and a low phase difference is achieved over the entire width of the film.

Fig. 5(a) is a view showing the phase difference subtraction when one multilayer laminated film is used. This is an example in which the full-width multilayer laminated film described in FIG. 4( a ) is cut in half and the traveling direction is reversed by 180° to overlap, and the refractive index ellipsoid is crossed in the same manner as in FIG. 4( b ). The subtraction effect of the phase difference works. On the other hand, in Fig. 5(b), when the traveling directions are aligned and folded from the center portion, the refractive index ellipsoids are superposed, and it is understood that the phase difference is added. These patterns are examples of controlling the phase difference by cleverly applying the line symmetry of the optical characteristics.

In the aggregate multilayer film of the present invention, in order to satisfy the formula (3), at least one or more multilayer laminated films having a main alignment axis or a relationship of 60 to 120° must be present. In order to make SRe 400 nm or less, the number of sets of the multilayer laminated film of the above relationship must be about n/2~(n-6)/2 sets (n≧2).

The phase difference SRe(k) of the multilayer laminated film of the formula (3) is synonymous with the total phase difference Re of the formula (1), but the phase difference here is not particularly limited. This is because the phase difference is important for the final form of application. For example, in a touch panel substrate, two types of ITO substrate films can be used in the GFF film sensor type. When the ITO process is performed on the first multilayer laminated film and the second multilayer laminated film, and the phase difference is not a problem, the phase difference of the laminated multilayer film of the present invention is important because it affects the interference color and the rainbow. spot. However, from the viewpoint that the low phase difference is relatively easy to control, the phase difference SRe(k) of the multilayer laminated film itself is preferably 400 nm or less.

The composite multilayer laminated film of the present invention comprises a layer of at least three or more layers laminated on the layer A including the crystalline resin a and the layer B containing the resin b having a lower crystallinity than the crystalline resin a. The composite multilayer laminated film of the C layer of the liquid crystal material, the phase difference Rth' of the total thickness direction of the composite multilayer laminated film and the phase difference Rth of the total thickness direction of the multilayer laminated film must satisfy the formula (4).

(4) Rth’<Rth

The liquid crystal material contains a structure in which the polymerizable liquid crystal composition has a liquid crystal compound (rod liquid crystal structure) having a polymerizable functional group in the molecule. The liquid crystal compound has a refractive index anisotropy and exhibits a desired phase difference function by imparting various alignment forms. The liquid crystal compound may, for example, be a material which exhibits a liquid crystal phase equivalent to a nematic phase, a cholesterol phase, and a smectic phase.

The liquid crystal compound can be polymerized and fixed by having a polymerizable functional group. The polymerizable functional group may, for example, be a photoradical polymerization type or a photocationic polymerization type which can be polymerized by the action of ultraviolet rays, electron beams or heat. Examples of the type of radical polymerization include a vinyl group, an acrylate group (including a general term of an acryloyl group, a methacryloyl group, an acryloyloxy group, or a methacryloxy group), and the like.

The liquid crystal material of the present invention preferably contains a photosensitive liquid crystal polymer. Further, it is preferable that the liquid crystal polymer contains a mesogenic component. Further, a side chain type liquid crystalline polymer material containing a liquid crystal original component in a side chain is preferable. As a material constituting the main chain, a hydrocarbon, C Alkenoate, methacrylate, vinyl, decane, maleimide, N-phenylmaleimide, and the like. The liquid crystal raw material may be composed of an aromatic ring such as a benzene ring, a naphthalene ring or an anthracene ring, or an aliphatic ring such as a cyclohexane ring or a linking group bonded thereto. For example, biphenyl, terphenyl, phenyl benzoate, azobenzene, and the like. The liquid crystalline polymer material may be a copolymer of a single polymer containing the same repeating unit or a unit having a side chain having a different structure. Further, a crosslinking agent for improving heat resistance or solvent resistance can be added to the extent that liquid crystallinity is not impaired. Examples of the crosslinking agent added to improve heat resistance include a crosslinking agent such as an isocyanate material or an epoxy material.

As a solvent for dissolving the liquid crystal material, a hydrocarbon solvent such as benzene or hexane; a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; tetrahydrofuran or 1,2-dimethoxy B; Alkane, propylene glycol monoethyl ether, methyl tert-butyl ether, 1,4-two An ether solvent such as dioxane, diglyme, ethylene glycol dimethyl ether, 1,3-dioxolane or 2-methyltetrahydrofuran; chloroform, dichloromethane, etc. a halogenated alkyl solvent; an ester solvent such as methyl acetate, ethyl acetate, butyl acetate or propylene glycol monomethyl ether acetate; a guanamine solvent such as N,N-dimethylformamide; An anthraquinone solvent such as a hydrazine; a cyclohexanone solvent such as cyclohexane; and an alcohol solvent such as methanol, ethanol or isopropyl alcohol. These solvents may be used alone or in combination of two or more.

When a solution which can be a layer C containing a liquid crystal material is applied onto a multilayer laminated film, it can be achieved by a method of gravure printing, flexographic printing, die slitting, or spin coating. The photosensitive liquid crystal polymer can be formed by subjecting it to a condensation reaction as described in JP-A-2007- 232934 and JP-A-2012-177087. Next, in order to cure the C layer and impart refractive index anisotropy, ultraviolet rays having a wavelength of 250 to 400 nm are irradiated. The light to be irradiated may be circularly polarized light or elliptically polarized light. However, from the viewpoint of anisotropically aligning the original portion of the liquid crystal in the photosensitive liquid crystal polymer, linearly polarized light is preferred. At this time, from the viewpoint of enhancing the photoreaction, it is preferred to reflect the ultraviolet ray having a wavelength of 400 nm or less in the multilayer laminated film. Since the ultraviolet light is reflected, the light hardening efficiency of the layer C can be improved. The reflectance at a wavelength of 350 nm is preferably 30% or more. More preferably 50% or more. From the viewpoint of the alignment control, if it is a negative C plate, light is irradiated from the normal direction or the direction oblique to the normal to the coated film surface. As the light source, any light source can be used as long as it emits ultraviolet rays, such as a high pressure mercury lamp or a xenon light source. The irradiation amount may be about 20 to 300 mJ/cm ² . Thereafter, by heat treatment at 70 to 150 ° C in a heat treatment, side chains which are not aligned by the polarized ultraviolet light are aligned and fixed.

The thickness of the liquid crystal material of the present invention is preferably from 0.1 μm or more to 10 μm or less from the viewpoint of seeking film formation and imparting anisotropy and exhibiting a phase difference in the thickness direction. More preferably, it is 0.5 μm to 5 μm or less. Since the multi-layer laminated film of the present invention uses the biaxially-oriented crystalline resin a, it tends to become a strong negative C plate. In the multilayer laminated film of the present invention, in order to eliminate the interference color found by the viewing angle under the crossed Nicols and to reduce the phase difference in the thickness direction, the C layer including the liquid crystal material is preferably a positive C plate. The negative C plate refers to a refractive index ellipsoid in which the refractive indices Nx and Ny in the in-plane direction are higher than the refractive index Nz in the thickness direction. On the other hand, the positive C plate indicates that the refractive index Nz in the thickness direction is higher than the in-plane direction. A material having a refractive index ellipsoid of refractive indices Nx and Ny. The method of making a positive C plate can be coated from The direction in which the normal direction of the surface is inclined by 45° or more and less than 90° is irradiated with the linearly polarized ultraviolet light, and then heat treatment is performed to cause the refractive index of the liquid crystal material to increase in the thickness direction. From the viewpoint of making it a positive C plate, it is more preferable to irradiate from an incident angle of 60° or more and less than 90°. The angle of incidence is the angle of inclination with respect to the normal to the surface of the coated film.

The relationship between the refractive index Nz in the thickness direction of the C layer of the present invention and the refractive indices N _X and N _Y in the in-plane direction preferably satisfies the following formulas (6) and (7).

(6) N _Z >N _X , N _Y

(7)N _Z ≧1.6

In general, the in-plane refractive index of the layer containing the biaxially-oriented crystalline resin a is 1.5 to 1.8, and the refractive index in the thickness direction is less than 1.6. Therefore, by satisfying the formula (6) and the formula (7), the thickness direction phase difference Rth' of the composite multilayer laminated film can be made smaller than the total thickness direction phase difference Rth of the multilayer laminated film. That is, the subtraction effect of the phase difference in the thickness direction is exerted. Further, the in-plane refractive index of N _X and N _Y is not particularly limited, but is preferably from 1.54 to 1.62 from the viewpoint of less reflection at the interface with the multilayer laminated film.

Further, the angle Φc-Φab| formed by the main alignment axis Φc of the C layer and the main alignment axis Φab of the multilayer laminated film is preferably 50° to 90°. The main alignment axis of the C layer can be controlled by rotating the "linear polarized light for photohardening the liquid crystal material" in the in-plane orientation. A Brewster angle caused by a polarizing plate containing two "polarizers for impregnating iodine with polyvinyl alcohol and extending" or two calcites may be applied, and a take-off bias may be used. The light of the Glan-Taylor prism makes a linear polarization.

The multilayer laminated film, the integrated multilayer laminated film, and the composite multilayer laminated film of the present invention are preferably used as an optical film. As the film for optics, it is preferably used for a flat panel display. For example, a cover film, a shatterproof film, a polarizer protective film, a retardation film, a base film for a touch panel, and a release film of a polarizing plate. The multilayer laminated film of the present invention is preferably used for a polarizer protective film, a retardation film, and a base film for a touch panel, from the viewpoint of low phase difference, unlike a general biaxially stretched PET film. The polarizer protective film is a material constituting two polarizing plates for a liquid crystal display, and can be used for the viewing side of the upper polarizing plate and the backlight side of the lower polarizing plate. Further, the polarizing plate is bonded to each other by a polarizer protective film and a retardation film through an adhesive, and is formed on both sides of a film in which iodine-impregnated polyvinyl alcohol is uniaxially stretched.

The multilayer laminated film of the present invention is preferably used for a touch panel. The touch panel of the present invention may be any of a resistive film type, an optical type, and an electrostatic capacity type. The electrostatic capacity type can be roughly classified into a projection type and a surface type. From the viewpoint of multi-touch, it is best to use a projection type electrostatic capacitance type. The conductive layer may be metal such as gold, silver, platinum, palladium, rhodium, indium, copper, aluminum, nickel, chromium, titanium, iron, cobalt, tin, and alloys of the metals, and tin oxide, indium oxide, titanium oxide, and oxidation. A composite film of a metal oxide film such as ruthenium, zinc oxide, cadmium oxide or indium tin oxide (ITO) or copper iodide. These transparent conductive films can be obtained by vacuum vapor deposition, sputtering, reactive RF ion plating, spray pyrolysis, electroless plating, electroplating, CVD, coating, or a combination of these methods. Further, as the conductive polymer, there are polypyrrole, polyaniline, polyacetylene, polythiophene, Polyphenylene. Stretching vinyl, polyphenylene sulfide, polyphenylene, polyheterocycle. Vinyl is extended, especially (3,4-extended ethyldioxythiophene) (PEDOT). Further, a carbon nanotube or a nano silver or the like also exhibits high conductivity and is therefore preferred. The components can be applied to the substrate by a coating method by dissolving the components in an organic solvent. The coating method can employ various methods in the same manner as the method of the hard coat layer. From the viewpoint of versatility, ITO is preferred.

As an external touch sensor, it can be roughly divided into a glass sensor and a film sensor. As a glass sensor type, there are GG, GG2, G2, G1M. GG is based on glass cover / ITO / glass / ITO, GG2 is based on glass cover / glass / ITO / insulation / ITO, G2 (OGS) is based on glass cover / ITO / insulation / ITO In the configuration, the G1M is based on a glass cover/ITO.

From the viewpoint of shatter prevention and suppression of light shielding, it is preferred to use the multilayer laminated film of the present invention between a touch panel and a liquid crystal panel. In this case, it is particularly preferable to use it as a glass sensor type.

On the other hand, the film sensor type has GFF, GF2, G1F, GF1, PFF, PF1, and any of them can be used. In addition, GFF is based on glass cover / ITO / film / ITO / film, GF2 is based on glass cover / ITO / film / ITO or glass cover / ITO / insulation / ITO / film, G1F is glass Cover/ITO/ITO/film is the basic structure, GF1 is based on glass cover/ITO/film, PFF is based on plastic cover/ITO/film/ITO/film, and P1M is based on plastic cover/ITO. Composition.

[Examples]

Hereinafter, the multilayer laminated film of the present invention will be described using examples.

[Methods for measuring physical properties and methods for evaluating effects]

The evaluation method of the characteristic value and the evaluation method of the effect are as follows.

(1) Layer thickness, number of layers, laminated structure

The layer structure was obtained by observing a sample of a cross section cut by a microtome by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The transmission electron microscope was used to observe a section of the film at an acceleration voltage of 75 kV by using an H-7100FA type (manufactured by Hitachi, Ltd.), and a cross-sectional image was taken to measure the layer constitution and the thickness of each layer. Further, as the case may be, in order to obtain high contrast, a conventional dyeing technique using RuO ₄ or OsO ₄ or the like can be utilized. The scanning electron microscope used JSM-6700F (Japan Electronics Co., Ltd.) to observe a section of the film at an acceleration voltage of 3 kV by 1500 times, and took a cross-sectional image to measure the layer constitution and the thickness of each layer.

(2) Glass transition temperature (Tg). Melting point (Tm). Melting enthalpy change (ΔHm)

Using a differential thermal analysis (DSC), the sample was heated from 25 ° C to 290 ° C at 5 ° C / min, measured according to JIS-K-7122 (1987). Calculate the transition point that appears at this time. In the DSC of 1stRun, two peaks appear, and the two peaks are divided to calculate ΔHm of two resins.

Device: "EXTRA DSC6220" manufactured by SII NANOTECHNOLOGY Co., Ltd. (formerly Seiko Denso Electronics Co., Ltd.)

Sample quality: 5 mg.

(3) The outermost layer refractive index

A 稜鏡 coupler (SPA-4000) manufactured by Sairon Technology was used. A film sample cut into 3.5 cm × 3.5 cm is set in the package Once placed, a 633 nm laser was irradiated and measured in TE mode, thereby measuring the in-plane refractive index of the outermost layer. The measurement was performed in the TM mode, thereby measuring the refractive index in the thickness direction of the outermost layer. The refractive index in the longitudinal direction is measured by setting the MD direction of the film in parallel with respect to the device, and the refractive index in the width direction is measured by being disposed in the vertical direction with respect to the device. The sampling system was sampled from the center of the film roll having a width of 600 mm. Further, the layer C formed in Example 17 was transferred onto a glass substrate, and the refractive indices in the in-plane and vertical directions (thickness directions) were measured in the same manner.

(4) In-plane phase difference (Re). Thickness direction phase difference (Rth). Alignment angle

A phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Machinery Co., Ltd. was used. A film sample cut into 3.5 cm x 3.5 cm was placed on the apparatus, and a retardation of a wavelength of 590 nm at an incident angle of 0 was measured. The sampling system was sampled from the center of the film roll having a width of 600 mm. The phase difference in the thickness direction is the phase difference of the incident angle of 50°.

(5) Measurement of phase difference between layer A and layer B of multilayer laminated film

In the case of a peelable multi-layer laminated film, after all the layers were physically peeled off, the phase difference of each layer was measured by KOBRA. In the case of a non-releasable multilayered film, the refractive index of the outermost layer (layer A) is measured by a 稜鏡 coupler, and the cross section of the film is observed by TEM, thereby measuring the total thickness of the layer of the same resin as the surface layer to calculate A. Layer Re(A).

(6) Evaluation of rainbow spots

A film sample of A4 size was placed on a 46-inch liquid crystal display manufactured by TCL Corporation. Next, when observed from the top and the oblique direction, the presence or absence of rainbow spots was evaluated.

(7) Measurement of the angle formed by the main alignment axis of the A layer and the main alignment axis of the B layer by Fourier transform infrared spectrophotometer (FT-IR)

Device name: FTS-55A made by Bio-Rad Dglab

Light source: special ceramic, detector: DTGS, condition: nitrogen environment, decomposition capacity 4cm ^-1 / cumulative number 128 times, measurement wave number area: 4000~6000cm ^-1 , measurement method: ATR method, incident angle 45°, polarized light S wave.

The sample was taken out from the center of the film in the width direction at a position of 250 mm, and the longitudinal direction of the film was 0°, and the polarized light was measured for one week in the in-plane direction at a scale of 15°, and the intensity distribution of the spectrum in the plane was determined. The highest value of the intensity ratio is taken as the main alignment axis. Moreover, the alignment evaluation in the thickness direction was performed using dry grinding.

Alignment evaluation spectral intensity ratio of spiroglycerol copolymerized polyethylene terephthalate layer

: peak ratio A1165cm ^-1 /A1410cm ^-1

Alignment evaluation spectral intensity ratio of isosorbide copolymerized polyethylene terephthalate layer

: peak ratio A1097cm ^-1 /A1410cm ^-1

Alignment evaluation spectral intensity ratio of polyethylene terephthalate layer

: peak ratio A1340cm ^-1 /A1410cm ^-1

(8) Measurement of relative spectral reflectance at a wavelength of 350 nm

A 5 cm square sample was cut out from the central portion in the film width direction of the multilayer laminated film. Next, a spectrophotometer (U-4100 Spectrophotomater) manufactured by Hitachi High-Technologies was used, and the relative reflectance of the spectral transmittance and the incident angle Φ = 10 degrees was measured. The inner wall of the attached integrating sphere is barium sulfate, and the standard plate is alumina. The measurement wavelength is set to 250nm~ 800 nm, the slit was set to 2 nm (visible), the gain was set to 2, and the measurement was performed at a scanning speed of 600 nm/min.

[Resin used]

The resin used was organized as follows.

Resin 1 Polyethylene terephthalate (PET): glass transfer temperature 80 ° C

Resin 2 24 mol% isophthalic acid copolymerized polyethylene terephthalate (PET-I24): glass transition temperature 74 ° C

Resin 3 6 mol% isophthalic acid copolymerized poly(cyclohexanedimethylene terephthalate (PCT-I6): glass transition temperature 90 ° C

Resin 4: PET-I24 and 15 mol% isosorbide, and 20 mol% cyclohexane dimethanol copolymerized polyethylene terephthalate in an equal amount of resin: glass transition temperature 95 ° C

Resin 5 nylon 6

Resin 6 6 mol% ethylene copolymerized polypropylene

Resin 7 17 mol% isophthalic acid copolymerized polyethylene terephthalate (PET-I17): glass transition temperature 76 ° C

Resin 8 12 mol% isophthalic acid copolymerized polyethylene terephthalate (PET-I12): glass transition temperature 78 ° C

Resin 9 30 mol% spiroglycerol copolymerized polyethylene terephthalate: glass transition temperature 100 ° C

Resin 10 copolymerized polyethylene terephthalate copolymerized with 20 mol% spiroglycerol component and 30 mol% cyclohexane dicarboxylic acid: glass transition temperature 80 ° C

(Example 1)

Resin 1 was used as the crystalline resin a and the resin 2 was used as the resin b. The crystalline resin a and the resin b were respectively subjected to 180 ° C. Dry for 3 hours, and pre-crystallize with a mixer to carry out 120 ° C. After 5 hours of drying, they were supplied to 2 extruders.

The crystalline resin a and the resin b were melted in a molten state of 270 ° C by an extruder, and passed through a filter of 40 μm mesh, so that the discharge ratio was a crystalline resin a composition/resin b composition = 0.55. In the manner, the number of rotations of the screw was adjusted, and the resin was combined into three layers of A/B/A by a feeding device to form a laminate. The laminate including the three layers obtained in this manner was extruded into a sheet shape from a slit-shaped mold, and then rapidly cooled and solidified on a casting drum to which an electrostatic holding surface temperature of 25 ° C was applied.

The obtained cast film was heated by a roller group set at 85 ° C, and the longitudinal extension temperature was set to 85 ° C while rapidly heating from both sides of the film by a radiant heater between the extension intervals of 100 mm. A 3.3-fold extension was performed in the longitudinal direction, followed by temporary cooling. Next, the uniaxially stretched film was introduced into a tenter, preheated by hot air at 95 ° C, and then stretched 3.6 times in the transverse direction at a temperature of 110 ° C. The stretched film was directly heat-treated in a tenter at a hot air of 210 ° C, and then subjected to a relaxation treatment of 5% in the width direction at the same temperature, and then slowly cooled to room temperature, and then wound to obtain a thickness of 42.9. Multilayer laminated film of μm.

The phase difference of the outermost surface layer of the obtained multilayer laminated film was calculated using a 稜鏡 coupler and SEM, and the phase difference Re of the entire multilayer laminated film was measured using KOBRA. The results are shown in Table 1. From this result, the total phase difference of the layer A composed of the same crystalline resin a as the outermost layer is known. Re (A) is larger than the phase difference of the laminated film. Therefore, the phase difference of the layer B with respect to the layer A is reduced. Further, the multilayer laminated film had a phase difference Re of 277 nm, which is a low retardation film of less than 400 nm. Therefore, when the rainbow spot was observed on the LCD, no rainbow spot was found at all.

(Example 2)

In Example 1, except that the resin 3 was used as the resin b, the discharge ratio (layering ratio) was changed to the crystalline resin a composition/resin b composition = 1.0, the longitudinal extension temperature was 105 ° C, and the longitudinal stretching ratio was 3.3 times. The experiment was carried out under the same conditions except that the lateral stretching temperature was 140 ° C and the lateral stretching ratio was 4.6 times. Comparing the phase difference between the surface layer of the multilayered laminated film obtained and the phase difference of the multilayer laminated film, it was found that the subtraction effect was larger than that of Example 1, and the phase difference was low. The results are shown in Table 1. This is because, compared with PET-I, PCT-I has a stronger alignment in the MD direction, and PCT-I itself has a higher glass transition temperature than PET, and its phase difference is larger, so it is considered to be more effective. Reduce the effect.

(Example 3)

The same resin as in Example 1 was joined by using a feeding device having a slit plate having a number of slits to form a laminate. The slit gap is designed in such a manner that adjacent layers are of the same thickness. The film formation conditions were set to be the same as in Example 1 except that the discharge ratio was a composition of the crystalline resin a/resin b = 0.25, a lateral extension temperature of 120 ° C, a lateral stretching ratio of 3.9 times, and a heat treatment temperature of 230 ° C. The same conditions. The results are shown in Table 1. Compared with Example 1, the result of the subtraction effect of the layer B of Example 2 was higher. I believe that this is because the thickness of the B layer is increased relative to the total thickness, and the phase subtraction effect is exerted more than that of the first embodiment.

(Example 4)

In Example 3, the resin 4 was used as the resin b to form a laminate. The other film forming conditions were set as follows: a longitudinal stretching temperature of 103 ° C, a longitudinal stretching ratio of 3.3 times, a lateral stretching temperature of 120 ° C, a lateral stretching ratio of 3.3 times, and a heat treatment temperature of 230 ° C. The results are shown in Tables 1 and 2. Even if the above resin is used in the resin b, the phase difference of the layer B is reduced with respect to the multilayer laminated film.

(Example 5)

The experiment was carried out under the same conditions as in Example 4 except that the same resin as in Example 4 was used, except that the longitudinal stretching ratio was 3.5 times and the lateral stretching ratio was 3.3 times. The results are shown in Table 2. Since the extension ratio in the MD direction is increased, although the overall phase difference is increased, the subtraction effect is hardly changed.

(Example 6)

Using the same resin as in Example 4, a layer feeder having a slit number of 491 slit plates was used to join the layers, and a layered body in which 491 layers were alternately laminated in the thickness direction was formed. However, in the slit plate used, the slit width of the thick film layer formed at both end portions is designed to be more than twice the width of the slit forming the other film layer, and the minimum layer thickness of the film layer is formed. The degree of inclination of the ratio of the maximum layer thickness is designed to be 0.3. Here, the slit width (gap) is set to a constant value, and only the length is changed.

The obtained laminated body was molded under the same conditions as in Example 5 except that the longitudinal stretching temperature was 98 ° C, the longitudinal stretching magnification was 3.3 times, the lateral stretching temperature was 140 ° C, and the lateral stretching magnification was 4.6 times. The results are shown in Table 2. As a result, the subtraction effect becomes larger as compared with Example 4.

(Example 7)

In Example 6, the experiment was carried out under all the same conditions except that the longitudinal stretching temperature was raised to 101 °C. The results are shown in Table 2. Compared with the embodiment, the longitudinal alignment becomes weak and the lateral magnification does not change. Therefore, although the overall phase difference increases, the alignment of the B layer does not change, so the subtraction effect is large.

(Example 8)

In Example 7, experiments were carried out under all the same conditions except that the lateral stretching ratio was lowered. The results are shown in Table 2. Compared with Example 7, the lateral magnification was lowered, and although the overall phase difference was lowered, the subtraction effect was almost unchanged as compared with Example 7.

(Example 9)

In Example 8, since the shrinkage ratio in the MD direction was reduced, additional stretching was performed in the heat treatment, and the final magnification was the same as in Example 7. The results are shown in Table 2. Compared with the embodiment 8, the overall phase difference is also reduced, and the subtraction effect is also maximized.

(Comparative Example 1)

In Example 1, except that the resin 5 was used as the crystalline resin a and the resin 1 was used as the resin b, the longitudinal stretching temperature was 80 ° C, the longitudinal stretching ratio was 3.3 times, the lateral stretching temperature was 105 ° C, and the lateral stretching ratio was 3.9. The experiment was carried out in the same manner except that the heat treatment temperature was 190 °C. The results are shown in Table 1. It can be seen that the phase difference of the nylon of the surface layer is lower than the total phase difference of the laminated film, and the phase difference of the PET layer of the inner layer with respect to the nylon increases.

(Comparative Example 2)

In the first embodiment, the resin 6 is used as the crystalline resin a and the resin 4 is used as the resin b, and the longitudinal stretching ratio is changed to 3.3 times, the lateral stretching ratio is changed to 4.1 times, and the heat treatment temperature is changed to 90° C. The same method. It can be seen that the phase difference of the inner layer of the film also increases with respect to the phase difference of the surface layer.

(Comparative Example 3)

In Example 1, the experiment was carried out under the same conditions except that the resin b was changed to the resin 7. The results are shown in Table 1.

(Comparative Example 4)

In Example 1, the experiment was carried out under the same conditions except that the resin b was changed to the resin 8. The results are shown in Table 1.

When the isophthalic acid copolymerization component was less than Comparative Examples 3 and 4, the difference in phase difference between the laminated film and the phase A of the layer A was large, and the resin b did not exhibit a subtractive effect.

(Comparative Example 5)

The experiment was carried out under the same conditions as in Example 4 except that the longitudinal stretching ratio was changed to 3.3 times and the lateral stretching ratio was changed to 3.5 times. The results are shown in Table 2. Although the overall phase difference is lowered, the longitudinal magnification is increased, so there is no effect of phase difference subtraction.

(Comparative Example 6)

In Example 1, all the resins were changed to Resin 1, and a PET single film was produced. The extension conditions were optimized, and a single film having a thickness of 40 μm, a phase difference of 1881 nm, and an alignment angle of 0° was produced. The phase difference reduction mechanism was studied by overlapping the single films and measuring the phase difference. The results are shown in Table 3. When the PET single film is overlapped without offset with respect to the longitudinal direction, the total phase difference of the film is the same as the added value of the two films. On the other hand, when two sheets of film are laminated at an angle with respect to the longitudinal direction, it is understood that the phase difference at 0° is reduced when the angle is shifted by 45° or more. It can be seen that as the offset is larger, the phase difference of the entire film is reduced more. From the above results, it was confirmed that the phase difference was reduced due to the difference in the main alignment axes of the two films which were overlapped.

A theoretical study of this phenomenon (Fig. 3). Polyethylene terephthalate-based refractive index ellipsoid, elliptic equation when only rotating angle θ is: AX ² + BXY + CY ² =1

A=(cos2θ/Nx1 ² +sin2θ/Ny1 ² )

B=2cosθsinθ(-1/Nx1 ² +1/Ny1 ² )

C=(cos ² θ/Ny1 ² +sin ² θ/Nx1 ² )

Therefore, the refractive indices of the second layer of the A layer in the X and Y directions are:

When the sizes of Nx2 and Ny2 are compared, θ ≧ 45° and Nx2 ≦ Ny2. Therefore, when the layer A of the first layer is viewed, the birefringence θ ≧ 45° or more of the second layer is a negative value. Here, when viewed from the first layer, the total phase difference Re is: Re = (Nx1 - Ny1) × Da + (Nx2 - Ny2) × Da'

In the above formula, the second term is a negative value, and therefore, it is considered that the phase difference of the entire film is reduced. That is, it is considered that the main alignment axes of the two films which are overlapped are deviated, and the phase difference is reduced. This consideration also considers the results in different films of two or more layers. Since the main alignment axes of adjacent films are different, the opposite of the fast axis and the slow axis with respect to the A layer occurs. As a result, the phase difference of each layer progresses in the decreasing direction, and as a result, the total phase difference is considered to be reduced.

The multilayer laminated film used in several examples and comparative examples of the present invention can detect the distribution of each layer by physical peeling at the interface of each layer. To the corner. The total phase difference of the film and the phase difference of each layer. The results of the alignment angle are shown in Table 4. In Example 4, the difference in the alignment angle between the A layer and the B layer was about 80°, and it was found that the difference between the inner layer and the outer layer was large. On the other hand, in Comparative Example 1 and Comparative Example 2, the alignment angle was the same as that of the outer layer and the outer layer. From the above results, it is considered that the film produced this time has a different alignment angle between the inner layer and the outer layer, so that the total phase difference of the film is reduced.

(Embodiment 10)

The resin 1 containing 0.04% by weight of agglomerated ceria having an average particle diameter of 2.5 μm as a lubricant was vacuum dried at 180 ° C for 3 hours, and then placed in a uniaxial extruder to be melted at an extrusion temperature of 280 ° C. And carry out mixing. After the filter was cut to a filtration accuracy of 30 μm, it was supplied to a T-shaped mold and formed into a sheet shape. Then, a 7 kV electrostatic printing voltage was applied to the wire, and the casting drum was kept at a surface temperature of 25 ° C. The film was cooled and solidified to obtain an unstretched film. The unstretched film was stretched by 3.5 times between the rolls in the longitudinal direction of the film at a longitudinal stretching machine at 85 ° C, and then introduced into a tenter which grasped both ends by a jig at 85 ° C. After performing a lateral stretching of 3.3 times in the film width direction, heat treatment at 215 ° C was carried out, and a relaxation treatment of about 3% was carried out in the film width direction at 150 ° C to obtain a polyester film having a thickness of 32 μm. The phase difference and the alignment angle of the obtained polyester film in the film width direction are as shown in Table 5. The main alignment axis is 40 to 60° in the width direction of the film, showing a uniform alignment angle distribution.

The obtained polyester film has a width of 600 mm and is cut every 1000 mm in the longitudinal direction to produce two sheets of 600 mm × 1000 mm, and the winding direction of one sheet is reversed, and the center portion, the center portion, and the end portion are formed. And end In the overlapping portion, the angle between the main alignment axes of the first sheet and the second sheet is 90°±15°, and the subtractive effect is exerted, and the optical adhesive SK-1478 manufactured by Amika Chemical Co., Ltd. is used. Dry laminate. The thickness of the optical adhesive was 25 μm, and the obtained multilayer laminated film was 3 layers and had a thickness of 89 μm.

The phase difference of the obtained three-layer film was uniform in the film width direction, and all of them were 50 nm or less, and the subtraction effect was confirmed. It is possible to improve the general polyethylene terephthalate used as a conductive substrate of a touch panel or a display for an antireflection (AR) substrate, that is, to obtain a multilayer laminated film having improved rainbow spots and interference colors. Further, in the touch panel substrate, a low phase difference of a GFF sensor type (GFF: glass cover/ITO/film/ITO/film touch panel) suitable for separately providing two ITO conductive films can be obtained. film.

(Example 11)

After the resin 1 was used as the resin a and vacuum-dried at 180 ° C for 3 hours, on the other hand, the resin 4 was dried as a resin b under nitrogen gas at 80 ° C, and then each was placed in a single axis by a transport line of each closed system. The extruder and the twin-screw extruder were further melted at a 280 ° C and 280 ° C extrusion temperature, respectively, and kneaded. Then, the two discharge holes of the twin-screw extruder are evacuated to a vacuum of 0.1 kPa or less to remove foreign matter such as oligomers or impurities, and then measured by a gear pump to make a discharge ratio (layering) In the case of the thermoplastic resin A/thermoplastic resin B=0.7/1, a laminate of 255 layers alternately laminated in the thickness direction was formed by a 255-layer laminating apparatus using the same principle as the laminating apparatus described in Patent No. 4552936. Moreover, the slit length and the interval are adjusted in such a manner as to be the thickness distribution of the layer protruding upward. The gap forms a layering device. For the A layer and the B layer, respectively, the corresponding layer numbers form an inclined structure having a thickness distribution of the convex layer. The A layer and the B layer alternately laminate 255 layers to make the layer thickness near the two surfaces of the laminated film thinnest. Then, the laminated body was supplied to a T-shaped mold, and after forming a sheet shape, a static electricity voltage of 8 kV was applied to the wire, and rapid cooling solidification was performed on a casting drum having a surface temperature of 25 ° C to obtain an unstretched film. . The unstretched film was stretched 3.2 times in the longitudinal direction of the film at 115 ° C, and then introduced into a tenter at the ends of the film by a clamp, at 110 to 140 ° C in the film. After a lateral stretching of 4.5 times in the width direction, a stepwise heat treatment at 180 ° C and 225 ° C was carried out, and a relaxation treatment of about 3% was carried out in the film width direction at 150 ° C to obtain a multilayer laminated film having a thickness of 13 μm. The layer thicknesses of the respective layers of the obtained multilayered film are all present in the range of 35 nm to 55 nm. The layer thickness distribution of the obtained multilayered film was formed into an asymptotic convex layer thickness distribution having an average layer thickness of 60 nm in the average layer thickness distribution. The obtained multilayer laminated film had a relative reflectance of 61% at a wavelength of 350 nm measured by a spectrophotometer. The alignment distribution of the A layer and the B layer was measured by FT-IR from the central portion in the film width direction to the position of 250 mm, and the results are shown in Fig. 6. The main alignment axis of the A layer exhibits 120° (300°), whereas the main alignment axis of the B layer is 30° (210°), and it is confirmed that the A layer and the B layer are perpendicular. Further, the total phase difference Re is 191 nm, and on the other hand, the refractive index difference (Nx(1) - Ny(1)) of the outermost layer measured by the 稜鏡 coupler and the total thickness d (A) of the A layer are The phase difference obtained was 400 nm, and it was confirmed that the phase difference in the in-plane direction at 209 nm was reduced. Further, the thickness direction phase difference Rth at an incident angle of 50° is 450 nm, and is disposed in On a 42-inch LCD monitor, even if the background color is white, it is a rainbow-free film. On the other hand, regarding the phase difference unevenness, the phase difference at 200 mm in the central portion in the film width direction was changed to 20 nm.

(Embodiment 12)

A multilayer laminated film of 255 layers was obtained in the same manner as in Example 11 except that the resin 9 was used as the resin b and the longitudinal stretching ratio was changed to 3.5 times. From the center of the film width direction to the position of 250 mm, the main alignment axis of the A layer is 135° (315°), whereas the main alignment axis of the B layer is 15° (195°), confirming the main layer A and B. The angle formed by the alignment shaft is 120°. Further, the total phase difference Re is 150 nm, and on the other hand, the refractive index difference (Nx(1)-Ny(1)) of the outermost layer measured by the 稜鏡 coupler and the total thickness d(A) of the A layer are The phase difference obtained was 235 nm, and the decrease in the phase difference in the in-plane direction of 55 nm was confirmed. Further, the thickness direction phase difference Rth at an incident angle of 50° was 398 nm, and this was placed on a liquid crystal display, and even if the background color was white, it was a rainbow-free film. On the other hand, regarding the phase difference unevenness, the phase difference at 200 mm in the central portion in the film width direction was changed to 10 nm. The obtained multilayer laminated film had a relative reflectance of 90% at a wavelength of 350 nm measured by a spectrophotometer.

(Example 13)

Next, in the same manner as in Example 12, a 491 layer having a thickness of 15.5 μm was obtained in the same manner as in Example 12 except that the resin 10 was used as the resin b, and the layering apparatus was changed to 491 layers, the longitudinal stretching temperature was changed to 105 ° C, and the lateral magnification was changed to 3.6 times. Multilayer laminated film. The phase difference of the obtained multilayer laminated film was 17 nm. A film having a phase difference of 201 nm in the end portion in the film width direction and having a very uneven phase difference in the width direction was obtained. Example 13 The distribution of the phase difference and the alignment angle of the multilayer laminated film to the film width direction is shown in Fig. 7. Fig. 7(a) shows the phase difference distribution, and Fig. 7(b) shows the alignment angle distribution. Further, as described in Fig. 4(a), the measurement position (X) in the film width direction is expressed by the relative position (±X/W) of the half value (W) of the full width of the film. The phase difference values were all below 400 nm, so no rainbow spots were observed and the quality was good. However, if observed under crossed nibs, the contrast of brightness is different in the film width direction.

(Example 14)

A 491-layer multilayer laminated film having a thickness of 15.5 μm was obtained in the same manner as in Example 13 except that the longitudinal stretching ratio of Example 13 was changed to 3.2 times. Since the resin b is not aligned, the phase difference subtraction effect is only about 6 nm. On the other hand, no rainbow spots were observed.

(Example 15 and Comparative Example 7)

Using the multilayer laminated film obtained in Example 13, a multilayer full-thickness laminated film of the full width was cut into a relationship caused by (a) phase difference subtraction and (b) phase difference addition described in FIG. Half of the film laminate was implemented in the two patterns. The phase difference distribution in the width direction of the obtained film is shown in Fig. 8 (a) and (b). Fig. 8(a) shows the phase difference distribution when the layer is laminated in the MD direction. In the full width direction, all of the phase differences are 40 nm or less, and a multi-layer laminated film having no rainbow spots and a uniform low phase difference is obtained. It was confirmed that the films are suitable for use in a film requiring two sheets of ITO substrates such as GFF type. On the other hand, Fig. 8(b) shows a phase difference distribution when the MD directions are aligned and folded to laminate. The phase difference is all increased, and it is understood that the phase difference in the width direction becomes larger. At the end phase difference greater than 400 nm, a rainbow spot was found.

(Embodiment 16)

The aggregated multilayer film obtained in Example 15 was cut at regular intervals from the film width direction at four intervals, and the film was attached with an adhesive to evaluate the phase difference. As a result, the phase difference SRe was 75 nm. On the other hand, when the sum of the phase differences of the multilayer laminated film at 8 o'clock in the film width direction, that is, the value of the formula (3) (n = 8), was 826 nm, the subtraction effect of the integrated multilayer laminated film was confirmed. These films are useful as good films for optical films without interference color.

(Example 17)

A multilayer laminated film of 255 layers was obtained in the same manner as in Example 11 except that the resin 10 was used as the resin b, and the longitudinal stretching temperature was changed to 110 ° C and the longitudinal direction was changed to 3.3 times. A sample was taken from a central portion in the width direction of the film and a position of 200 mm, and then a liquid crystal material was applied onto the multilayer laminated film to form a C layer.

The C layer was synthesized by 4-(6-hydroxyhexyloxy)cinnamic acid, and then methacrylic acid was added in the presence of p-toluenesulfonic acid to carry out an esterification reaction to obtain a compound 1. Dissolving the obtained compound 1 in two In the alkane, azobisisobutyronitrile was added as a reaction initiator, and polymerization was carried out at 70 ° C for 24 hours to obtain a polymer. This was dissolved in a tetrahydrofuran/propyl carbonate mixed solution to prepare a solution having a solid concentration of 25% by weight. After application to a thickness of 2 μm by a spin coating apparatus, preliminary heating was carried out to obtain a photosensitive liquid crystal polymer. Using Glan-Taylor, the incident angle of 60 degrees or more is inclined from the normal direction of the coating film surface of the film, and ultraviolet irradiation by linearly polarized light is performed, and then heat treatment is performed at 120 ° C to form a characteristic having positive C plate. The C layer of the liquid crystal material. The refractive index N _{Z in} the thickness direction of the C layer was 1.69, and the refractive index N _X and N _{Y in the in-} plane direction were 1.56, which was confirmed to be a positive C plate. The subtraction effect of the obtained phase difference in the thickness direction is summarized in Table 6. Before the formation of the C layer, coloration was observed in the observation of the crossed nibble in the oblique direction. However, it was confirmed by KOBRA that the phase difference between the central portion in the width direction of the film and the value of 200 mm was reduced by about 50 nm in the thickness direction. According to the quadratic function approximation, the phase difference in the thickness direction at 90° has a reduction effect of about 208 nm. It was also colorless in the observation under crossed nibs, and a composite multilayer laminated film suitable for a display or the like was successfully obtained. The results of the phase difference in the thickness direction before and after the application of the C layer are shown in Table 7. It is also confirmed that the angle Φc-Φab| formed by the main alignment axis Φc of the C layer and the main alignment axis Φab of the multilayer laminated film is in the range of 50° to 90°.

Claims (13)

A multilayer laminated film in which a layer A comprising a biaxially-oriented crystalline resin a and a layer B containing a resin b lower than the crystalline resin a are alternately laminated with at least three or more layers. The characteristic is that when the phase difference from the surface layer to the kth layer is Re(k) and the total number of layers is n, the total phase difference Re of the multilayer laminated film satisfies the formulas (1) and (2); (2) Re≦400nm. A multilayer laminated film comprising a layer A containing a crystalline resin a and a first multilayer film including at least two or more layers of a B layer having a crystallinity lower than that of the resin b of the crystalline resin a, and a second multilayer laminate The film is sequentially superposed to the aggregate multilayer film formed by the k-th multilayer film, and the integrated multilayer film is characterized in that the phase difference of the multilayer laminated film in the kth layer is SRe(k), and all the multilayer layers are laminated. When the number of films is n, the total phase difference SRe as an aggregate of the multilayer laminated film satisfies the formula (3); k is a natural number; A composite multilayer laminated film comprising a layer of at least three or more layers in which an A layer containing a crystalline resin a and a B layer containing a resin b lower than the crystalline resin a are alternately laminated. A composite multilayer laminated film of a C layer of a liquid crystal material characterized by a phase difference Rth' of a total thickness direction of the composite multilayer laminated film and The phase difference Rth in the total thickness direction of the multilayered laminated film satisfies the formula (4); (4) Rth' < Rth. The multi-layer laminated film according to claim 1, wherein the layer A comprising the biaxially-oriented crystalline resin a and the layer B containing the resin b having a lower crystallinity than the crystalline resin a are alternately laminated at least three or more layers. In the multilayered film, the refractive index in the direction of the maximum refractive index in the in-plane direction is Nx (1) and the refractive index in the direction perpendicular thereto is Ny (1) on the outermost surface layer of the film. When the total thickness of the layer composed of the same resin as the outermost layer is d (A) and the total phase difference of the multilayer laminated film is Re, it satisfies the formula (5); (5) Re-(Nx(1) -Ny(1)) × d(A)<0. The multilayer laminated film according to claim 1 or 4, wherein the resin b comprises a component selected from the group consisting of isophthalic acid, spiroglycerol, isosorbide, hydrazine, bisphenol A, and cyclohexane dimethanol. One of the ingredients in a group. The multilayer laminated film according to any one of claims 1 to 4, wherein the crystalline resin a is selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate. A group of diesters. The multilayer laminated film according to any one of claims 1 to 4, wherein the glass transition temperature of the crystalline resin a is lower than the glass transition temperature of the resin b. The multi-layer laminated film according to any one of claims 1, 4, 5, 6 and 7, which is inclined in the longitudinal direction of the main alignment axis with respect to the multilayer laminated film The multilayer laminated film of 10 to 80°, wherein the main alignment axis of the A layer included in the multilayer laminated film forms an angle of 60 to 120° with the main alignment axis of the B layer. The multilayer laminated film according to any one of claims 1, 4, 5, 6, 7, and 8, wherein the phase difference in the film width direction is not 50 nm/200 mm or less. The multilayer laminated film according to any one of claims 1, 4, 5, 6, 7, and 9, wherein the reflectance at a wavelength of 350 nm is 20% or more. The composite multilayer laminated film according to claim 3, wherein the relationship between the refractive index N _{Z in} the thickness direction of the C layer and the refractive indices N _X and N _Y in the in-plane direction satisfies the formulas (6) and (7); (6) N _Z >N _X , N _Y (7)N _Z ≧1.6. The composite multilayer laminated film according to claim 11, wherein the angle Φc-Φab| formed by the main alignment axis Φc of the C layer and the main alignment axis Φab of the multilayer laminated film is 50° to 90°. The multilayer laminated film or the integrated multilayer laminated film or the composite multilayer laminated film according to any one of claims 1 to 12, which is used as an optical film.