TWI730966B - Multilayer laminated film - Google Patents

Abstract

The present invention is a laminated film in which at least 3 layers are alternately laminated with a layer A containing a biaxially oriented crystalline resin a and a layer B containing a resin b with lower crystallinity than the crystalline resin a The film is characterized in that when the retardation from the surface layer to the k-th layer is set to Re(k) and the total number of layers is set to n, the total retardation Re of the multilayer laminate film satisfies equations (1) and (2) ). Even if biaxially oriented, crystalline resin with high mechanical strength, and resin with high birefringence is used, a film with low retardation can be provided.

(2) Re≦400nm.

Description

Multilayer laminated film

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

Liquid crystal display devices using liquid crystal display panels as display elements are used as thin display devices such as liquid crystal televisions, liquid crystal monitors, and personal computers, and their uses are rapidly expanding. In particular, the market for LCD TVs and mobile phones has expanded significantly.

The liquid crystal display device must use a polarizing plate, and the polarizing plate generally uses a polarizer protective film. From the viewpoint of high transparency and optical isotropy, triacetyl cellulose (hereinafter referred to as TAC) film is widely used as its film . However, from the viewpoints of chemical resistance and scratch resistance, it cannot be said that TAC films have exhibited sufficient performance. With the development of large and thin liquid crystal displays in recent years, heat resistance, mechanical strength, and size Stability, high moisture permeability, etc. become issues.

In response to the above-mentioned problems, other amorphous resins such as cycloolefin polymers or acrylic resins have also been studied to replace TAC films (Patent Documents 1 and 2). However, in most cases, almost no extension is provided, and general-purpose resins are not used. There is a problem that the cost becomes higher.

On the other hand, some people have also studied the crystallinity of polyester film Resin replaces the TAC film (Patent Document 3). Among them, compared with TAC film, polyethylene terephthalate (hereinafter referred to as PET) film has lower moisture permeability and excellent handling properties. It is a general-purpose resin and has the advantage of reducing costs, so it is often used use. However, a film formed of a crystalline resin such as a PET film generally requires treatment such as uniaxial stretching or biaxial stretching, and the phase difference may increase due to 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 viewed through a polarizer such as polarized sunglasses, rainbow unevenness or interference colors can be seen problem. On the contrary, in the non-stretched state, it has the advantage of suppressing the generation of light interference colors. On the other hand, it has the problem of significant reduction in strength, and is not suitable for the protective film of the polarizing plate that has been in demand for thinning in recent years.

Furthermore, some people have proposed a retardation film that uses a multilayer structure and uses structural birefringence and molecular orientation birefringence, and requires more retardation accuracy than a polarizer protective film (Patent Document 4). However, in order to exhibit structural birefringence, the average layer thickness is made to be an extremely thin 30nm or less, and a special resin combining an amorphous resin with negative optical anisotropy and an isotropic amorphous resin, and the thickness and total layer The number is also very large, so it has the problem of high material and manufacturing costs. That is, even if it satisfies the optical performance, its characteristics are the same as those of the conventional amorphous resin, and it is not a material that satisfies the film, low cost, low moisture permeability, and dimensional stability.

[Prior Technical Literature] [Patent Literature]

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

[Patent Document 2] JP 2006-227090 A

[Patent Document 3] JP 2013-200470 A

[Patent Document 4] Japanese Patent No. 4489145

The problem to be solved by the present invention is to provide a film, which is a multi-layer laminated film with a biaxially oriented layer A and a layer B with a poorer alignment. The phase difference between the A layer and the B layer is subtracted. In order to provide a low retardation film, even when it is used as a polarizer protective film to be mounted on a large-screen liquid crystal display or other display device, the contrast, rainbow spots, and interference color are less changed, and high-quality display can be obtained.

The inventor of the present case conducted in-depth research and found that when making a film with a layer A containing a biaxially oriented resin and a layer B with a poorer alignment, the combination of the resin and the film forming conditions were optimized. , The retardation of the entire multilayer build-up film becomes lower than the sum of the retardation of the A layer and the B layer. In-depth research was conducted, and as a result, the following findings were obtained: In this multilayer laminate film, the main alignment axes of the A layer and the B layer are different, so the retardation of the entire film is reduced, thereby completing the present invention.

That is, the present invention is as follows.

[1] A multi-layer laminate film in which at least three layers are alternately laminated with a layer A containing a biaxially oriented crystalline resin a and a layer B containing a resin b with a lower crystallinity than a, which The characteristic is that when the retardation from the surface layer to the k-th layer is set to Re(k) and the total number of layers is set to n, the total retardation Re of the multilayer laminate film satisfies the equations (1) and (2).

(2)Re≦400nm

[2] The multi-layer laminated film as in [1], which alternately laminate at least 3 layers A layer containing a biaxially oriented crystalline resin a and a layer B containing resin b whose crystallinity is lower than the crystalline resin a A multilayer laminate film having more than one layer is characterized in that on the outermost surface layer of the film, the refractive index in the direction giving the maximum refractive index in the in-plane direction is set to Nx(1), and the refractive index in the direction perpendicular to it is set to Ny (1) When the total thickness of the layer body composed of the same resin as the outermost surface layer is set to d(A), and the total retardation of the multilayer laminate film is set to 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 any component selected from the group consisting of isophthalic acid, spiroglycerin, isosorbide, stilbene, bisphenol A, and cyclohexanedimethanol. More than one ingredient in a group.

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

The present invention has low retardation, so it can be used for retardation films, polarizer protective films with retardation function, and substrates for touch panels Film etc. In addition, the unevenness of the retardation or the unevenness of the alignment angle in the width direction is also small, so even when it is mounted as a polarizer protective film on a display device such as a large-screen liquid crystal display, the following effects can be exerted: contrast, rainbow spots, or The interference color changes little, and a high-quality display can be obtained.

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

Figure 2 is a schematic diagram showing the direction of light penetration when the same resin is overlapped.

Fig. 3(a) is a schematic diagram when two single-film films are stacked. Figure 3(b) is a schematic diagram showing the relationship between refractive index ellipsoids when two single-film thin films are stacked.

Figure 4(a) shows the refractive index ellipsoid distribution in the width direction of the multilayer film. (b) It is the refractive index ellipsoid distribution of the multilayer multilayer film in the width direction when two multilayer multilayer films are stacked.

Figure 5(a) is a schematic diagram of the phase difference subtraction using a full-width multilayer laminate film. Figure 5(b) is a schematic diagram of the phase difference addition using a full-width multilayer laminate film.

Figure 6 shows the alignment distribution of the A layer and the B layer of the multilayer laminate film of Example 11.

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

Figure 8(a) shows the MD direction of the multilayer laminate film of Example 13 reversed The phase difference distribution in the width direction of the film when the two sheets are rotated and bonded together. Figure 8(b) shows the phase difference distribution in the film width direction when the MD direction of the multilayer laminate film of Example 13 is aligned and two sheets are bonded together.

[The form of implementing the invention]

Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the interpretation of the embodiments including the following examples. Of course, various modifications can be made within the scope that the object of the invention can be achieved without departing from the gist of the invention.

In addition, unless otherwise specified, the in-plane retardation of the film or layer is a value represented by (Nx-Ny)×d. Here, Nx represents the refractive index in the direction perpendicular to the thickness direction of the film or layer (in-plane direction), that is, the direction in which the maximum refractive index is imparted. Ny represents the refractive index of the in-plane direction of the film or layer, that is, the direction perpendicular to the Nx direction. d represents the film thickness of the film or layer. Unless otherwise specified, the measurement wavelength of the above-mentioned 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 Measurement Instruments Co., Ltd., "WPA-micro" manufactured by Photonic Lattice) or the Senarmont method.

The multilayer laminated film of the present invention is a film in which at least three layers of crystalline resin a and resin b are alternately laminated. The alternate layering mentioned here refers to layers containing different resins in a regular arrangement in the thickness direction. For example, in the case of containing crystalline resin a and resin b, if each layer is expressed as layer A and layer B , It is layered in a regular arrangement like A(BA)n (n is a natural number). In addition, the outermost surface layer of the multilayer laminate film may also have a layer C containing resin c to form C{A(BA)n}C such a structure. In the multilayer laminate film of the present invention, when the retardation from the surface layer to the k-th layer is Re(k) and the total number of layers is n, the total retardation Re of the multilayer laminate film satisfies the following formula (1). k is a natural number.

The above formula means that "the retardation Re of the entire multilayer laminate film obtained by using a commercially available measuring device" is smaller than the "value obtained by individually measuring, calculating the retardation of each layer, and adding each retardation." Here, in the case of measuring the phase difference of each layer, a commercially available measuring device can be used to measure a thin film that is peeled off each layer to become a single film, or the surface layer can be polished with a plastic polishing cloth as described in Japanese Patent Application Laid-Open No. 2014-149346. The measurement is performed after making each layer into a single layer. The greater the subtractive effect of the phase difference, the stronger the alignment crossover is displayed. From this viewpoint, the subtraction effect is preferably 50 nm or more. More preferably, it is 100 nm or more.

In addition, in general, when the film is formed by successive biaxial or uniaxial stretching under the same film forming conditions, the higher the crystallinity of the resin, the greater the in-plane phase difference. Therefore, the phase difference of the film when the crystalline resin a is used The difference is set to Re(a), and the retardation of the film is set to Re(b) when using resin b with lower crystallinity than the resin a, then (8) Re(a)>Re(b)

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

Here, Re(1) is the phase difference of the outermost layer of the multilayer laminate film, and Nx(1) and Ny(1) are the refractive index and perpendicular to the direction that gives the outermost layer the maximum refractive index in the plane direction, respectively The refractive index in the direction of, d(1) is the thickness of the outermost surface layer, and D'is the total thickness of the layer using the same resin as the outermost surface layer in the multilayer laminate film. Next, this formula will be described. The refractive index in the in-plane direction of the outermost surface layer can be obtained by using an ellipsometer, a spectrophotometer, a coupler, an Abbe refractometer, etc. Then, because the thickness can be measured by using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), the phase difference of the outermost surface layer can be easily calculated. When the resin of the inner layer and the outermost surface layer are the same resin, if the film forming conditions are the same, assuming that the birefringence of the outermost surface layer and the inner layer are the same, the retardation of the inner layer can be estimated. Therefore, the phase difference can be measured when the outermost surface layer of the multilayer laminate film is the same resin. Here, if a layered body composed of the same resin as the outermost surface layer has a retardation added value greater than the total retardation Re of the multilayer laminate film, the equation (1) of claim 1 is satisfied. That is, it represents the retardation of the layer body of the resin different from the outermost surface layer, and exerts the effect of subtracting the retardation for the multilayer laminate film.

Here, the retardation subtraction effect of the multilayer laminate film will be described. Regarding the two-layer film described in Figure 1, if the refractive index in the in-plane direction of the A layer is set to Nx(a), Ny(a), and the refractive index in the in-plane direction of the B layer is set to Nx(b ), Ny(b), then the birefringence of layer A is The birefringence of (Nx(a)-Ny(a)) and layer B is (Nx(b)-Ny(b)), so the total retardation Re of the two-layer film described in Figure 1 is: Re=(Nx(a)-Ny(a))×d(a)+(Nx(b)-Ny(b))×d(b)

At this time, if layer B and layer A are the same resin, assuming this layer is A', as shown in Figure 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 retardation Re of the multilayer laminate film is obviously the sum of the retardation of each film. Therefore, in general, the sum of the retardation obtained from the refractive index and thickness of each layer should be the same value as the retardation of the laminated film measured using a commercially available measuring device.

On the other hand, in the present invention, the crystalline resin a and the resin b with lower crystallinity are used, and the film forming conditions are intensively studied, thereby successfully making the "total phase difference Re of the multilayer film" better than the "phase difference of each layer" The "additional value of the difference" is further reduced. The following describes the details of the mechanism, which are derived from the different main alignment axes of each layer.

(2)Re≦400nm

Moreover, as shown in the formula (2), the overall retardation Re of the multilayer build-up film, that is, the retardation in the in-plane direction, must be 400 nm or less. By satisfying this condition, it is easy to obtain a multilayer laminate film with the following characteristics: even if viewed through polarizers such as sunglasses, it is not easy to see The interference color is measured. The interference color under crossed Nichol is related to the phase difference value, which can be seen from the Michel-Levy chart. When performing "crossed Nico observation in a vertical relationship with the polarizer", from the viewpoint of colorlessness, it is more preferably 200 nm or less. More preferably, it is 100 nm or less. The method to achieve this is to intensively study the following resin composition and film forming conditions.

On the outermost surface layer of the multilayer laminate film of the present invention, the refractive index in the direction giving the maximum refractive index in the in-plane direction is set to Nx(1), and the refractive index in the direction perpendicular to it is set to Ny(1). When the total thickness of the layer body composed of the same resin as the outermost surface layer is set to d(A), and the total retardation of the multilayer laminate film is set to 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. More preferably, it is -100 nm or less. The best is -150nm or less. In order to increase the subtractive effect, from the viewpoint of aligning the B layer which is more difficult to align than the A layer, the build-up ratio, that is, the total thickness of the A layer/the total thickness of the B layer is preferably 1 or less. More preferably, it is 0.7 or less. In addition, the glass transition temperature of resin b used for layer B is preferably 88°C or higher.

The multilayer laminate film of the present invention must use biaxially oriented crystalline resin a and resin b with a lower crystallinity than a. Biaxially alignable resin refers to a resin whose refractive index in the in-plane direction is higher than the refractive index in the thickness direction when stretched in the longitudinal direction and width direction of the film. It can be easily measured using optical measuring devices such as a scalp coupler. In addition, the crystalline resin is a resin having a glass transition temperature Tg and a melting point Tm, and it is a resin having a melting enthalpy change ΔHm>0. The △Hm of the crystalline resin is preferably Above 10J/g. More preferably, it is 20J/g. In addition, the crystallinity of the resin b must be lower than that of the crystalline resin a, and it may include an amorphous resin. If the crystallinity of the crystalline resin a and the resin b is different, the main alignment axis of the A layer and the B layer in the multilayer laminate film can be changed during successive stretching according to the film forming conditions suitable for the resin. As a method of evaluating crystallinity, it is known that the ΔHm measured by DSC can be evaluated. The greater the △Hm, the greater the energy consumed for melting, and the higher the crystallinity. Therefore, the ΔHm of the crystalline resin a must be higher than the ΔHm of the resin b. That is, the relationship of △Hm(a)>△Hm(b) is established. In addition, the resin b may be an adhesive, adhesive, and curable resin having tackiness.

Furthermore, it is preferable that the glass transition temperature difference 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 latter paragraph, and in the present invention, successive biaxial extensions are used, and the transverse extension is implemented after the 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, when the glass transition temperature of resin b is higher than the glass transition temperature of crystalline resin a, and the longitudinal stretching is performed under the condition of the glass transition temperature of resin b + 5°C, layer A cannot be aligned, and the other On the other hand, compared to the A layer, the longitudinal alignment of the B layer becomes stronger. Then, by performing lateral stretching at a temperature higher than the vertical stretching temperature, and then performing heat treatment, since the A layer is crystalline, it is crystallized in alignment in the width direction and then thermally crystallized. On the other hand, the B layer is easy to The longitudinal alignment remains. As a result, the main alignment axes of the A layer and the B layer can be deviated. Therefore, the difference in the glass transition temperature is preferably 5°C or more. On the other hand, if the difference in the glass transition temperature is too large, it cannot be extended uniformly, resulting in poor thickness uniformity, which in turn makes the phase difference relative to the longitudinal It becomes uneven in the width direction. Therefore, the difference in the glass transition temperature is preferably 40°C or less.

As the crystalline resin a and resin b with lower crystallinity than the multilayer film used in the present invention, specifically, polyethylene, polypropylene, poly(4-methylpentene-1), polycondensation resin can be used. Polyolefins such as aldehydes, norbornenes as cyclic olefins, ring opening metathesis polymerization, addition polymerization, aliphatic polyolefins of addition copolymers with other olefins, and polylactic acid. Biodegradable polymers such as polybutyl succinate, polyamides such as nylon 6, 11, 12, and 66, polyaramide (aramid), polymethyl methacrylate, polyvinyl chloride, polyvinylidene Vinyl chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymerization polymethyl methacrylate, polycarbonate, polyterephthalate Polyesters such as propylene formate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalenedicarboxylic acid, polyether ketone, polyether ketone, and modified polyphenylene Ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, acrylonitrile. Butadiene. Styrene copolymers, etc. Among them, from the viewpoints of strength, transparency, and versatility, it is preferable to use polymethyl methacrylate, polycarbonate, and polyester. Particularly preferred is polyester. These resins can be homopolymers, copolymerized polymers, or even mixtures of thermoplastic resins. In addition, various additives such as antioxidants, antistatic agents, nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, slip agents, infrared absorbers, ultraviolet absorbers, Dopants to adjust the refractive index, etc.

As the polyester, a polyester obtained by polymerizing a monomer mainly composed of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol is preferable. Here, as the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6- Naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl diphenyl dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, etc. Examples of aliphatic dicarboxylic acids include adipic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and ester derivatives of these acids. Among them, it is preferable to use terephthalic acid and 2,6 naphthalenedicarboxylic acid that exhibit a high refractive index. Only one kind of these acid components may be used, or two or more kinds may be used in combination, and it is even possible to partially copolymerize oxyacids of hydroxybenzoic acid and the like.

In addition, as the glycol component, ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1, 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, spiroglycerin, etc. Among them, ethylene glycol is preferably used. These glycol components may use only 1 type, and may use 2 or more types together.

Among the above polyesters, it is preferable to use polyethylene terephthalate and its copolymers, polyethylene naphthalate and its copolymers, polybutylene terephthalate and its copolymers, and polynaphthalene Butylene dicarboxylate and its copolymers, more preferably polyhexamethylene terephthalate and its copolymers, polycyclohexane dimethyl terephthalate and its copolymers, etc. are used.

The best resin combination of the present invention, as the biaxially oriented crystalline resin a, includes polyethylene terephthalate and polyethylene naphthalate Either of diesters and polybutylene terephthalate, as resin b having a lower crystallinity than crystalline resin a, a copolymer of crystalline resin a is preferred. The resin b is preferably a copolymer having one or more components selected from the group consisting of isophthalic acid, spirolglycerin, isosorbide, pyruvate, bisphenol A, and cyclohexane dimethanol. Polyester. For example, it is preferable to use isophthalic acid copolymerized polyethylene terephthalate, spiroglycerol copolymerized polyethylene terephthalate, isosorbide copolymerized polyethylene terephthalate, and Copolymerized polyethylene terephthalate, bisphenol A copolymerized polyethylene terephthalate, polycyclohexane dimethyl terephthalate resin. From the viewpoint of the layering property with the crystalline resin a and the subtractive effect of the phase difference, the copolymer component is preferably 5 mol% or more and 50 mol% or less. If it is less than 5 mol%, the additive effect is likely to be exhibited. On the other hand, if it is 50 mol% or more, there is a possibility that the subtractive effect cannot be interfered. From the viewpoint of making the total retardation Re of the multilayer build-up 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 sequential biaxially stretched film, by setting the stretching temperature in the longitudinal direction above the glass transition of resin b, the layer B containing resin b is aligned in the longitudinal direction, but the layer A containing resin a is not in the longitudinal direction上Alignment. Then, when the horizontal stretching is performed at a temperature higher than the vertical stretching temperature, the A layer containing resin a is easily aligned in the horizontal direction. On the other hand, the B layer containing resin b remains in the state of being aligned in the vertical direction while guiding Heat treatment step. Then, the A layer undergoes alignment crystallization in the lateral direction. In addition, this is due to the addition of bowing phenomena, which realizes the different cross-alignment of the main alignment axes of the A layer and the B layer. State, and the subtractive effect of the phase difference easily occurs. The glass transition temperature of the resin b is preferably higher than that of the resin a by 10°C or more, more preferably 20°C or more. For example, when the resin a is polyethylene terephthalate, its 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 still more preferably 95°C or more.

Next, a description will be given of a preferable manufacturing method of the film of the present invention.

First, crystalline resin a and resin b in the form of pellets or the like are prepared. According to the demand, the pellets can be dried in hot air or vacuum, and then supplied to each extruder. In the extruder, the resin that has been heated and melted to a melting point or higher is homogenized with a gear pump or the like, and the foreign matter and modified resin are removed through a filter or the like.

The crystalline resin a and resin b sent from different flow paths using two or more extruders are then sent to the multilayer lamination device. As a multi-layer lamination device, a multi-split mold, feed block, static mixer, or the like can be used. Moreover, these devices can be combined arbitrarily. Among them, in order to efficiently obtain the effects of the present invention, a multi-split mold or feeder capable of individually controlling the thickness of each layer is preferred. The structure of the feeder is that there is at least one member on a comb-shaped slit plate with a large number of fine slits, and the crystalline resin a and resin b supplied from two extruders are introduced into the slit through each branching part. board. Here, through the introduction plate, crystalline resin a and resin b flow alternately, so A/B/A/B/. . . Such a multilayer structure. In addition, the number of layers can also be increased by overlapping the slit plates. In addition, the thickness of the layer body can be controlled by adjusting the slit shape (length, gap). In addition, a third other extruder can also be used to laminate The outermost surface layer of the film is provided with a layer C containing resin c. The manufacturing methods of the laminated devices and multilayer laminated films are described in detail in Japanese Patent Laid-Open No. 2007-307893 and Japanese Patent Laid-Open No. 2007-79349, and these methods are preferably used. From the viewpoint of generating additional functions such as "phase difference control" and "light interference reflection caused by the layer of light wavelength level", the number of layers is preferably 9 or more. It is more preferably 50 layers or more, and even more preferably 200 layers or more. If the number of build-up layers is too large, build-up disorder such as flow marks is likely to occur. From this point of view, it is preferably 600 layers or less. In addition, the average layer thickness is preferably 0.04 to 10 μm. If it is less than 0.04μ, the optical properties and material properties of each layer are lost, which is not good. 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 reflection of ultraviolet rays and maintaining transparency, it is preferably 0.04 to 0.06 μm or 0.11 to 5 μm.

It is preferable to extrude the molten body multi-layered in this way from a slit-shaped mold into a sheet shape, apply static electricity or other means to adhere it to a casting drum, and cool and solidify to form an unstretched sheet. , Stretching and heat treatment in two directions. In addition, in order to make the film have functions such as mobility (easy slippery), weather resistance, and heat resistance, particles may be added to the film raw material, but sufficient attention must be paid to the amount and material to avoid impairing the high transparency of the film. The addition amount is preferably a very small amount, and more preferably no addition. Regarding the mobility (easy-slip properties) of the film, as described above, it is preferable to assist with the additive particles of the easy-adhesion layer. As the particle material added to the film raw material, additives can be used, for example, heat-resistant stabilizers, antioxidant stabilizers, weather-resistant stabilizers, and ultraviolet absorbers; slip agents can be polyimide, polyimide-imide, and polymethylmethacrylate. Methyl acrylate, formaldehyde resin, phenol Organic particles such as aldehyde resin and cross-linked polystyrene; wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin can also be used , Clay and other inorganic particles.

Preferably, the laminated film obtained in this way is subjected to simultaneous biaxial, successive biaxial, oblique stretching and heat treatment. Here, biaxial stretching refers to stretching 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 the extension is preferably extended in two directions successively. In addition, it is also possible to re-extend in the longitudinal direction and/or the width direction after biaxial extension.

Explains the successive biaxial extension. Here, the extension in the long-side direction refers to the extension used to impart molecular alignment in the long-side direction of the film, and is generally implemented by the difference in the circumferential velocity of the rollers. The extension can be carried out in one stage, and, It can also be performed in multiple stages using multiple roller pairs. The stretching magnification varies depending on the type of resin, and it is generally preferably 2 to 15 times. When PET is used for any of the resins constituting the multilayer laminate film, it is particularly preferable to use 2 to 7 times. In addition, the stretching temperature is preferably the glass transition temperature of the resin constituting the multilayer laminate film-the glass transition temperature + 100°C. Here, particularly in the laminated film of the present invention, it is preferable that the alignment of either the crystalline resin a or the resin b in the longitudinal extension is strong. In order to strengthen the alignment, the preferred extension condition is to extend from the glass transition temperature of -10°C to +10°C. Therefore, if the glass transition temperature of resin b is higher, it is preferably at the glass transition temperature of resin b ±10 2.8~3.7 times extension is performed within ℃. It is more preferable to extend 3.3 to 3.7 times within the glass transition temperature of resin b +10°C.

According to the demand, the uniaxially stretched film obtained in this way is subjected to surface treatments such as corona treatment, flame treatment, plasma treatment, etc., and then it can be given slippery, slippery properties by in-line coating. Easy bonding, antistatic and other functions.

In addition, the extension in the width direction refers to the extension for imparting the orientation in the width direction of the film, and the tenter method is generally used. It is conveyed while gripping both ends of the film with a clamp, and stretches in the width direction. The stretching magnification varies depending on the type of resin, but it is generally preferably 2 to 15 times. When PET is used for any of the resins constituting the multilayer laminate film, it is particularly preferable to use 2 to 7 times. In addition, the stretching temperature is preferably the glass transition temperature of the resin constituting the multilayer laminate film-the glass transition temperature + 120°C.

Here, particularly in the multilayer laminate film of the present invention, in order to suppress the retardation in the width direction of the film and to improve the uniformity of the retardation and the alignment angle in the width direction of the film, it is preferable to adopt the following method: When stretching, the stretching temperature is gradually raised from a low temperature to a high temperature; when stretching in the width direction of the film, stretching is performed at a high stretching ratio and then stretching at a low stretching ratio. One of the reasons for the decrease in the width direction uniformity of the phase difference and the alignment angle is mostly due to the elongation stress acting in the direction of the flow of the film when elongating in the width direction. Here, by adopting the above method, when the film is stretched in the width direction, the stress generated in the film flow direction can be controlled, and the stress in the film width direction can be relatively increased. Therefore, the phase difference and the distribution in the film width direction can be achieved. Homogenization of high angles. In the present invention, it is preferable to perform stretching by 3.3 to 4.6 times at a lateral stretching temperature of 100°C or higher.

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

In order to impart flatness and dimensional stability to the film biaxially stretched in this way, it is preferable to perform a heat treatment at a stretching temperature or higher and lower than its melting point in a tenter. By performing heat treatment to thermally crystallize, the thermal dimensional stability is improved. After heat treatment in this way, after uniformly slow cooling, it is cooled to room temperature and winding is performed. In addition, it is also possible to combine relaxation treatments and the like when performing slow cooling from the heat treatment according to needs.

Here, particularly in the multilayer laminate film of the present invention, in order to suppress uneven retardation in the film width direction, it is preferable to perform heat treatment after stretching in the film width direction and temporarily cooling to a glass transition temperature or lower. In this case, by cooling to below the glass transition temperature, the stretching stress in the film flow direction in the stretching step in the film width direction can be controlled, and as a result, the uniformity of the retardation in the film width direction can be improved.

Moreover, in the multilayer build-up film of the present invention, it is preferable to raise the temperature during the heat treatment stepwise. When the temperature at the end of the stretching in the width direction of the film is set to T1, the temperature at the start of the heat treatment is set to T2, and the highest temperature of the heat treatment step is set to T3, it is more preferable that T2 is T1+10°C or higher and T3 Below -10°C, T2 is more preferably in the range of (T1+T3)/2±10°C. In this way, even if the heat treatment temperature is raised in stages, the stretching 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 increased. Uniformity of position difference. Furthermore, in the multi-layer build-up film of the present invention, in the heat treatment step, it is preferable to stretch such that the film width after the stretching step in the width direction of the film is 1.01 times or more and 1.2 times or less. In the heat treatment step, almost no stress is generated in the long side direction of the film, so the phase difference in the width direction and the uniformity of the alignment angle can be improved. On the other hand, when the stretching magnification in the width direction of the film in the heat treatment step is greater than 1.2 times, the film may have uneven thickness, and on the contrary, the retardation may deteriorate. From the viewpoint of thinning, the thickness of the obtained multilayer laminated film is preferably 30 μm or less. More preferably, it is 20 μm or less. More preferably, it is 15 μm or less.

The multi-layer laminated film of the present invention is a multi-layer laminated film whose main alignment axis is inclined from 10 to 80° with respect to the width direction. The angle formed by the main alignment axis of layer A and the main alignment axis of layer B contained in the multi-layer laminated film Preferably it is 60~120°. The main alignment axis system indicates the direction with the highest refractive index among the in-plane refractive indices, 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 based on KOBRA-21ADH, which can only measure the total phase difference Re. The 稜鏡 coupler can only directly obtain the refractive index of the outermost surface layer. On the other hand, by using the polarization ATR method of FT-IR for measurement, the alignment parameters can be used to directly measure the main alignment axis of each layer. Next, a detailed description will be given. As an alignment parameter, polyethylene terephthalate or isophthalic acid copolymerized polyethylene terephthalate can be detected by measuring 1340 cm-1 (CH ₂ longitudinal rocking vibration: reverse The ratio of the peak intensity of formula)/1410cm-1 (aromatic ring: C=C stretching vibration) to obtain the main alignment axis. Next, the isosorbide copolymerized polyethylene terephthalate system can regard the peak intensity of isosorbide, that is, the ratio of the peak intensity at 1097 cm-1/1410 cm-1 as the alignment parameter. On the other hand, Spiroglycerin copolymerized polyethylene terephthalate takes the ratio of the peak intensity of 1165cm-1/1410cm-1 as the alignment parameter, and detects the in-plane directions respectively to obtain the main alignment axis . If the angle formed by the main alignment axis of the A layer and the main alignment axis of the B layer contained in the multilayer laminate film is less than 60° or more than 120°, the subtractive effect of the retardation will be reduced, so it is preferably 70°~110 °. More preferably, it is 80°~100°. In addition, the method of independently obtaining the alignment parameters of the A layer and the B layer can be measured by dry polishing in the thickness direction.

In addition, in the multi-layer build-up film of the present invention, the retardation unevenness in the film width direction is preferably 50 nm/200 mm or less. If the retardation unevenness exceeds 50nm/200mm, color irregularities may occur when used as a polarizer protective film in display applications. More preferably, it is 30nm/200mm or less.

The multi-layer build-up film of the present invention preferably has a reflectance of 20% or more at a wavelength of 350 nm. This is because, in the use of a polarizer, in order to prevent the light degradation of the polarizer, the polarizer protective film is required to have a UV-blocking function. In addition, for the layer C formed of the following liquid crystal material, the curing reaction caused by radical polymerization caused by light mainly uses light near the I line with a wavelength of 365 nm. If the multilayer laminate film itself reflects ultraviolet light, the ultraviolet light applied to the photoreaction will not escape from the bottom surface of the coating film and be reflected back to the original place, but will be irradiated to the coating film again. Therefore, the photo-alignment speed of the liquid crystal material of the C layer is accelerated, and it is easy to form a photo-alignment film that realizes the desired anisotropy. The reflectance is more preferably 30% or more. More preferably, it is more than 50%.

The multi-layer laminated film of the present invention is composed of a layer A containing a crystalline resin a and a layer B containing a resin b having a lower crystallinity than the crystalline resin a At least two or more layers of the first multi-layer laminated film and the second multi-layer laminated film are laminated in this order to an assembly of the k-th multi-layer laminated film. When the retardation of the multilayer laminate film in the k-th layer is Re(k) and the number of all multilayer laminate films is n, the total retardation SRe as an aggregate of the multilayer laminate film must satisfy the following formula (3 ). k is a natural number.

By satisfying the above formula, it means that when a plurality of multi-layer laminated films are superimposed, a subtractive effect of the phase difference is exhibited in the collective multi-layer laminated film. From the viewpoint of suppressing interference colors or rainbow spots, 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 subtractive effect of the retardation, the natural number n of the number of laminated multilayer films is 2 or more. Also, it is preferably a multiple of 2. This is because if the layers are alternately laminated so that the main alignment axis of each multi-layer laminated film is perpendicular, the phase difference is easily subtracted. Adhesives, adhesives, or air may also exist between the laminates of each multilayer laminate film. These ingredients may contain various additives such as ultraviolet absorbers, pigments, and light stabilizers. In addition, it is also possible to perform processing of a metal or metal oxide, which is obtained by vapor deposition or the like, and it is almost independent of the phase difference. The overlapped multi-layer laminated film may have different sampling positions in the width direction of the multi-layer laminated film obtained by the same film forming process. Alternatively, it may be a multilayer laminated film having different resin compositions.

Next, with regard to "in a multilayer laminate film with uneven retardation or greater unevenness in the alignment angle due to the bow-shaped zigzag phenomenon, the overlap of the multilayer laminate film achieves a low phase phase across the entire width of the film. The method of achieving "differentiation" will be explained. Here, the bow-shaped zigzag phenomenon refers to the following film deformation behavior: In the manufacturing method of the successive biaxially stretched film, the marking ink line drawn in the width direction of the film before the tenter becomes The position of the tenter clip is a fixed-rotating arcuate curve. The mechanism is due to the shrinkage stress of the Poisson’s ratio that acts in the opposite direction to the direction of travel during the lateral extension, pulling the film in the heat-fixed area into the extension area.

Based on the refractive index ellipsoid distribution in the film width direction when the multilayer laminate film of the present invention is produced, the subtraction effect of the retardation will be described in detail using Fig. 4. Figure 4(a) shows the refractive index ellipsoid distribution in the width direction of the multilayer laminate film. It is the refractive index ellipsoid distribution in the width direction of the film cut from the full width sample of the multilayer laminate film. The C position represents the center part in the film width direction. The film formation by successive biaxial stretching has the following characteristics: due to the above-mentioned bowing phenomenon, the birefringence (phase difference) at the end of the width direction of the film becomes larger, and the inclination (alignment angle) of the main alignment axis is also the same. And become bigger. 2W represents the size of the film width. The arrow direction of MD (Machine Direction) indicates the direction of film travel. 2W depends on the size of the manufacturing device, which is generally 0.5~2m or more.

The alignment angle and phase difference here are respectively the overall alignment angle and phase difference of each layer in the thickness direction of the film that can be measured by KOBRA. Next, Fig. 4(b) shows the refractive index ellipsoid distribution of the multilayer multilayer film in the width direction when the two multilayer multilayer films are stacked. For the same multi-layer laminate film cut from different positions in the longitudinal direction, it is the refractive index ellipsoid distribution of two full-width multi-layer laminate films that are overlapped by 180° in the direction of travel. Excluding the central part, it can be seen that the two-layer multilayer is thin The refractive index ellipsoids of the film intersect. As a result, the phase difference is subtracted, and the phase difference is reduced across the entire width of the film.

Fig. 5(a) is a schematic diagram showing the phase difference subtraction when one multilayer laminate film is used. This is an example in which the full-width multilayer laminate film described in Figure 4(a) is cut in half, and the direction of travel is reversed by 180° to overlap. In the same way as Figure 4(b), the refractive index ellipsoids intersect, and it can be seen that The subtraction effect of the phase difference comes into play. On the other hand, in Fig. 5(b), when the direction of travel is aligned and folded from the center, the refractive index ellipsoids overlap, and it can be seen that they exert the additive effect of the phase difference. These diagrams are examples of controlling the phase difference by cleverly applying the line symmetry of the optical characteristics.

In order to satisfy the formula (3) in the collective multi-layer laminate film of the present invention, at least one group of two multi-layer laminate films whose main alignment axis is perpendicular or in a relationship of 60 to 120° must exist. In order to make the SRe below 400nm, the number of groups of the multilayer laminate film in the above relationship must be about n/2~(n-6)/2 groups (n≧2).

The retardation SRe(k) of the multilayer laminate film itself of the formula (3) is synonymous with the total retardation Re of the formula (1), but the retardation here is not particularly limited. This is because the phase difference is important in the final form applied. For example, in the touch panel substrate, GFF thin film sensor type, two ITO substrate films can be used. When ITO is processed separately for the first multi-layer laminate film and the second multi-layer laminate film and used as a base film, the retardation is not a problem. The retardation of the collective multi-layer laminate film of the present invention is very important because it affects the interference color and rainbow. spot. However, from the viewpoint of relatively easy control of low retardation, the retardation SRe(k) of the multilayer laminate film itself is preferably also 400 nm or less.

The composite multi-layer laminated film of the present invention is a multilayer laminated film in which at least 3 layers are alternately laminated on a layer A containing a crystalline resin a and a layer B containing a resin b whose crystallinity is lower than the crystalline resin a. For the C-layer composite multilayer laminate film of the liquid crystal material, the phase difference Rth' in the total thickness direction of the composite multilayer laminate film and the retardation Rth in the total thickness direction of the multilayer laminate film must satisfy the formula (4).

(4) Rth’<Rth

The liquid crystal material includes a polymerizable liquid crystal composition having a structure including a liquid crystal compound (rod-shaped liquid crystal structure) having a polymerizable functional group in the molecule. The liquid crystal compound has refractive index anisotropy and exhibits a desired retardation function by imparting various alignment forms. Examples of the liquid crystal compound include materials that exhibit liquid crystal phases such as a nematic phase, a cholesterol phase, and a smectic phase.

Since the liquid crystal compound has a polymerizable functional group, several kinds of liquid crystal compounds can be polymerized and fixed. As the polymerizable functional group, for example, a photoradical polymerization type or a photocationic polymerization type that can be polymerized by the action of ultraviolet rays, electron beams, and heat can be mentioned. Examples of radical polymerization types include vinyl groups, acrylate groups (collective names including acryloyl groups, methacryloyl groups, acryloyloxy groups, and methacryloyloxy groups), and the like.

The liquid crystal material of the present invention preferably contains a photosensitive liquid crystal polymer. In addition, the liquid crystal polymer preferably contains a mesogenic component. More preferably, it is a side chain type liquid crystalline polymer material containing a mesogen component in the side chain. Examples of materials constituting the main chain include: hydrocarbons, propylene Acrylate, methacrylate, vinyl, silicone, maleimide, N-phenylmaleimide, etc. The mesogen component may be composed of an aromatic ring such as a benzene ring, a naphthalene ring, and a sulphur ring, or an aliphatic ring such as a cyclohexane ring, and a linking group bonded to it. For example, biphenyl, terphenyl, phenyl benzoate, azobenzene, etc. This liquid crystalline polymer material may be a single polymer containing the same repeating unit or a copolymer of units having side chains with different structures. In addition, to the extent that the liquid crystallinity is not impaired, a crosslinking agent for improving heat resistance or solvent resistance may be added. Examples of the crosslinking agent added to improve heat resistance include crosslinking agents such as isocyanate materials and epoxy materials.

烷(dioxane)、二乙二醇二甲醚(diglyme)、乙二醇二甲醚、1,3-二氧戊環、2-甲基四氫呋喃等的醚系溶劑；氯仿、二氯甲烷等的鹵化烷基系溶劑；乙酸甲酯、乙酸乙酯、乙酸丁酯、丙二醇單甲醚乙酸酯等的酯系溶劑；N,N-二甲基甲醯胺等的醯胺系溶劑；二甲基亞碸等的亞碸系溶劑；環己烷等的環己酮系溶劑；甲醇、乙醇、異丙醇等的醇系溶劑該等溶劑可單獨或組合二種以上使用。 As solvents for dissolving liquid crystal materials, hydrocarbon solvents such as benzene and hexane; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; tetrahydrofuran, 1,2-dimethoxyethane Alkane, propylene glycol monoethyl ether, methyl tertiary butyl ether, 1,4-bis

Ether solvents such as dioxane, diglyme, ethylene glycol dimethyl ether, 1,3-dioxolane, 2-methyltetrahydrofuran, etc.; chloroform, dichloromethane, etc. Halogenated alkyl-based solvents; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; amine-based solvents such as N,N-dimethylformamide; dimethyl Substance-based solvents such as trisulfide; cyclohexanone-based solvents such as cyclohexane; alcohol-based solvents such as methanol, ethanol, and isopropanol can be used singly or in combination of two or more.

When the solution that can be the C layer containing liquid crystal material is coated on the multilayer laminate film, it can be achieved by gravure printing, flexographic printing, die slit printing, and spin coating. The photosensitive liquid crystal polymer can be formed by subjecting it to a condensation reaction as described in JP 2007-232934 and JP 2012-177087. Next, in order to harden the C layer and impart refractive index anisotropy, ultraviolet rays with a wavelength of 250 to 400 nm are irradiated. The irradiated light may be circularly polarized light, elliptically polarized light, etc., but from the viewpoint of anisotropically aligning the mesogen in the photosensitive liquid crystal polymer, linearly polarized light is preferred. At this time, from the viewpoint of improving the photoreaction, it is preferable to reflect ultraviolet light having a wavelength of 400 nm or less on the multilayer build-up film. Because by reflecting ultraviolet rays, the photohardening efficiency of the C layer can be improved. The reflectance at a wavelength of 350 nm is preferably 30% or more. More preferably, it is 50% or more. From the viewpoint of alignment control, if it is a negative C plate, light is irradiated from a normal direction or a direction inclined from an oblique normal to the coating 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 can be about 20~300mJ/cm ² . After that, by performing a heat treatment at 70 to 150° C., the alignment and fixation of side chains and the like that are not fixed due to polarized ultraviolet light are fixed.

The thickness of the liquid crystal material of the present invention is preferably 0.1 μm or more and 10 μm or less from the viewpoint of seeking thin film formation and the viewpoint of imparting anisotropy and exhibiting a phase difference in the thickness direction. More preferably, it is 0.5 μm to 5 μm or less. The multi-layer laminated film of the present invention uses biaxially oriented crystalline resin a, so it is easy to become a strong negative C plate. In the multi-layer laminated film of the present invention, in order to eliminate the interference color found at the viewing angle under crossed Nicolas, the subtractive effect of the retardation in the thickness direction is required. Therefore, the C layer containing the liquid crystal material is preferably a positive C plate. The negative C plate refers to a refractive index ellipsoid with the refractive index Nx and Ny in the in-plane direction higher than the refractive index Nz in the thickness direction. On the other hand, the positive C plate refers to the refractive index ellipsoid with the refractive index Nz in the thickness direction higher than that in the in-plane direction. A material of refractive index ellipsoid with refractive index Nx and Ny. The method of making positive C plate can be from the coating It is achieved by irradiating linearly polarized ultraviolet light with an orientation inclined at 45° or more and less than 90° with respect to the normal direction of the surface, and then performing heat treatment to increase the refractive index of the liquid crystal material 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 indicates the angle of inclination relative to the normal to the surface of the coating film.

The relationship between the refractive index Nz in the thickness direction of the C layer of the present invention and the refractive index 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

Generally, the in-plane refractive index of the layer system 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 making the C layer satisfy formulas (6) and (7), the thickness direction retardation Rth' of the composite multilayer laminate film can be made smaller than the total thickness direction retardation Rth of the multilayer laminate film. That is, the subtractive effect of the retardation in the thickness direction is exhibited. In addition, the _{in-plane refractive index of N X} and N _Y is not particularly limited, but from the viewpoint of reducing reflection at the interface with the multilayer laminate film, it is preferably 1.54 to 1.62.

Furthermore, the angle |Φc-Φab| formed by the main alignment axis Φc of the C layer and the main alignment axis Φab of the multilayer laminate film is preferably 50° to 90°. The main alignment axis of the C layer can be controlled by rotating the "linear polarization used to harden the liquid crystal material" in the in-plane orientation. It can be applied to a polarizing plate containing "a polarizer in which iodine is impregnated in polyvinyl alcohol and stretched" or the Brewster angle caused by two pieces of calcite, and the polarizer can be taken out. Light Glan-Taylor prism (Glan-Taylor prism) and make linear polarization.

The multi-layer laminated film, the collective multi-layer laminated film, and the composite multi-layer laminated film of the present invention can preferably be used as an optical film. As an optical film, it can be preferably used for flat panel displays. For example, cover films, anti-shatter films, polarizer protective films, retardation films, base films for touch panels, and release films for polarizing plates. The multi-layer laminated film of the present invention is different from general biaxially stretched PET films. From the viewpoint of low retardation, it can be preferably used for polarizer protective films, retardation films, and base films for touch panels. Polarizer protective film is a material that constitutes two polarizers used in liquid crystal displays. It can be used on the viewing side of the upper polarizer and the backlight side of the lower polarizer. In addition, the polarizing plate has a configuration in which a polarizer protective film and a retardation film are bonded to both sides of a film uniaxially stretched with iodine-impregnated polyvinyl alcohol through an adhesive.

The multilayer laminate film of the present invention can preferably be used for touch panels. The touch panel of the present invention can be any of a resistive film type, an optical type, and an electrostatic capacitance type. The capacitance type can be roughly classified into a projection type and a surface type. From the viewpoint of multi-touch capability, the projection type electrostatic capacitance type is most preferable. The conductive layer can be made of gold, silver, platinum, palladium, rhodium, indium, copper, aluminum, nickel, chromium, titanium, iron, cobalt, tin and other metals and alloys of these metals, and tin oxide, indium oxide, titanium oxide, oxide Metal oxide films such as antimony, zinc oxide, cadmium oxide, indium tin oxide (ITO), and composite films such as copper iodide are formed. The transparent conductive films can be obtained by vacuum evaporation, sputtering, reactive RF ion plating, spray thermal decomposition, chemical plating, electroplating, CVD, coating, or a combination of these methods. In addition, as conductive polymers, there are polypyrrole, polyaniline, polyacetylene, polythiophene, Polyphenylene. Vinylene, polyphenylene sulfide, polyphenylene, polyheterocyclic ring. The vinylidene group is particularly preferably (3,4-ethylenedioxythiophene) (PEDOT). In addition, carbon nanotubes or silver nanotubes also show high conductivity and are therefore preferred. By dissolving these components in an organic solvent, they can be coated on the substrate by a coating method. The coating method can adopt various methods in the same way as the hard coat method. From the viewpoint of versatility, ITO is preferred.

As an external touch sensor, it can be roughly divided into glass sensors and thin-film sensors. As the 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/insulating layer/ITO, and G2 (OGS) is based on glass cover/ITO/insulating layer/ITO Composition, G1M is based on glass cover/ITO.

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

On the other hand, thin film sensor types are 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/insulating layer/ITO/film, and G1F is based on 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 constitute.

[Example]

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

[Measurement method of physical properties and evaluation method of effect]

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

(1) Layer thickness, number of layers, and layer structure

The layer composition is obtained by observing a sample whose cross-section is cut with a microtome through a transmission electron microscope (TEM) or a scanning electron microscope (SEM). The transmission electron microscope used the H-7100FA model (manufactured by Hitachi, Ltd.), and observed the cross section of the film at an acceleration voltage of 75 kV at a magnification of 40,000 times, and took a cross-sectional image to measure the layer composition and thickness of each layer. In addition, depending on the situation, in order to obtain high contrast, a conventional dyeing technique _{using RuO 4} or OsO _{4 can be used.} The scanning electron microscope uses JSM-6700F (JEOL Co., Ltd.) to observe the cross-section of the film at an acceleration voltage of 3kV at a magnification of 1500 times, and take the cross-sectional image to measure the layer composition and thickness of each layer.

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

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

Device: "EXTRA DSC6220" made by SII NANOTECHNOLOGY Co., Ltd. (formerly Seiko Instruments Inc.)

Sample mass: 5mg.

(3) Refractive index of the outermost surface layer

Use the iron coupler (SPA-4000) manufactured by Sairon Technology. Set the film sample cut into 3.5cm×3.5cm in the package Set it on, irradiate a 633nm laser, and measure in TE mode to measure the in-plane refractive index of the outermost surface layer. The measurement is performed in the TM mode, whereby the thickness direction refractive index of the outermost surface layer is measured. The refractive index in the longitudinal direction was measured by setting the film in the MD direction parallel to the device, and the refractive index in the width direction was measured by setting it in the vertical direction with respect to the device. Sampling is performed from the center of a film roll with a width of 600 mm. In addition, the C layer made in Example 17 was transferred to a glass substrate, and the refractive index in the plane and in the vertical direction (thickness direction) was measured by the same method.

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

A phase difference measuring device (KOBRA-21ADH) manufactured by Oji Measuring Instruments Co., Ltd. was used. A thin film sample cut into 3.5cm×3.5cm was set on the device, and the retardation at a wavelength of 590nm at an incident angle of 0° was measured. Sampling is performed from the center of a film roll with a width of 600mm. The retardation in the thickness direction is the retardation at an incident angle of 50°.

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

In the case of peelable multilayer laminate films, after physically peeling off all the layers, the phase difference of each layer is measured by KOBRA. In the case of non-peelable multi-layer laminated film, measure the refractive index of the outermost surface layer (layer A) with a 稜鏡 coupler, and observe the cross-section of the film with TEM to measure the total thickness of the layer of the same resin as the surface layer to calculate A Re(A) of the layer.

(6) Evaluation of rainbow spots

The A4 size film sample was set on a 46-inch liquid crystal display manufactured by TCL Corporation. Next, when obliquely observed from directly above, the presence or absence of rainbow spots was evaluated.

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

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

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

The sample is taken out of the position 250mm from the center of the film width direction, the film longitudinal direction is 0°, and the in-plane direction is measured with a scale of 15° in a circle to obtain the in-plane intensity distribution of the spectrum. The highest value of the intensity ratio is used as the main alignment axis. In addition, dry polishing was used to evaluate the alignment in the thickness direction.

Alignment evaluation of the spiroglycerin copolymerized polyethylene terephthalate layer to evaluate the spectral intensity ratio

：Peak ratio A1165cm ^-1 /A1410cm ^-1

Alignment evaluation of isosorbide copolymerized polyethylene terephthalate layer for spectral intensity ratio

：Peak ratio A1097cm ^-1 /A1410cm ^-1

Alignment evaluation of polyethylene terephthalate layer spectral intensity ratio

：Peak ratio A1340cm ^-1 /A1410cm ^-1

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

A 5 cm square sample was cut out from the center part of the multi-layer laminated film in the film width direction. Next, using a Hitachi High-Technologies spectrophotometer (U-4100 Spectrophotomater), the spectral transmittance and the relative reflectance at an incident angle Φ=10 degrees were 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~ The measurement is performed at 800 nm, the slit is set to 2 nm (visible), the gain is set to 2, and the scanning speed is 600 nm/min.

[Resin used]

The resins used are organized as follows.

Resin 1 Polyethylene terephthalate (PET): Glass transition temperature 80℃

Resin 2 24mol% isophthalic acid copolymerization polyethylene terephthalate (PET-I24): glass transition temperature 74℃

Resin 3 6mol% isophthalic acid copolymerization polycyclohexane dimethyl terephthalate (PCT-I6): glass transition temperature 90℃

Resin 4 A resin in which PET-I24 is mixed with 15 mol% isosorbide and 20 mol% cyclohexanedimethanol copolymerized polyethylene terephthalate in equal amounts: glass transition temperature 95°C

Resin 5 Nylon 6

Resin 6 6mol% ethylene copolymerized polypropylene

Resin 7 17mol% isophthalic acid copolymerization polyethylene terephthalate (PET-I17): glass transition temperature 76℃

Resin 8 12mol% isophthalic acid copolymerization polyethylene terephthalate (PET-I12): glass transition temperature 78℃

Resin 9 30mol% spiroglycerin copolymerized polyethylene terephthalate: glass transition temperature 100℃

Resin 10 Copolymerized polyethylene terephthalate in which 20 mol% of spiroglycerin components and 30 mol% of cyclohexanedicarboxylic acid are copolymerized: glass transition temperature 80°C

(Example 1)

The resin 1 was used as the crystalline resin a, and the resin 2 was used as the resin b. The crystalline resin a and resin b were subjected to 180°C. After 3 hours of drying and pre-crystallization with a mixer, proceed to 120°C. After 5 hours of drying, each was supplied to two extruders.

The crystalline resin a and the resin b were melted at 270°C with an extruder, and passed through a 40μm mesh filter so that the discharge ratio was crystalline resin a composition/resin b composition=0.55 In this way, the number of rotations of the screw is adjusted, and the resin is merged into three layers of A/B/A with a feeding device to form a laminate. The laminate containing the three layers obtained in this manner was extruded from a slit-shaped mold into a sheet shape, and then rapidly cooled and solidified on a casting drum whose surface temperature was maintained at 25° C. by applying static electricity.

After heating the obtained cast film with a group of rollers set at 85°C, the longitudinal stretching temperature was set to 85°C while rapidly heating the film from both sides of the film with a radiant heater between the stretching section length of 100mm. Stretched 3.3 times in the longitudinal direction, and then temporarily cooled. Next, the uniaxially stretched film was introduced into a tenter and preheated with hot air at 95°C, and then stretched 3.6 times in the transverse direction at a temperature of 110°C. The stretched film is directly heat-treated in a tenter with hot air at 210°C, and then subjected to a 5% relaxation treatment 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 μm multilayer laminate film.

The phase difference of the outermost surface layer of the obtained multilayer laminate film was calculated by using a 稜鏡 coupler and SEM, and the phase difference Re of the entire multilayer laminate film was measured using KOBRA. The results are shown in Table 1. From this result, it can be seen that the total retardation of the A layer composed of the same crystalline resin a as the outermost surface layer Re(A) is greater than the retardation of the laminated film. Therefore, the phase difference of the B layer with respect to the A layer is reduced. In addition, the retardation Re of the multilayer build-up film is 277 nm, which is a low retardation film of less than 400 nm. Therefore, when observing rainbow spots on the LCD, no rainbow spots were found at all.

(Example 2)

In Example 1, except that resin 3 was used as resin b, the discharge ratio (layer ratio) was crystalline resin a composition/resin b composition = 1.0, the longitudinal elongation temperature was 105°C, and the longitudinal elongation ratio was 3.3 times. The experiment was performed under the same conditions except that the lateral stretching temperature was 140°C and the lateral stretching magnification was 4.6 times. Comparing the retardation of the surface layer of the obtained multilayer build-up film with the retardation of the multilayer build-up film, it can be seen that the subtractive effect is greater than that of Example 1, and the retardation is 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 the glass transition temperature of PCT-I itself is higher than that of 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 combined with a feeder using a slit plate having 9 slits to form a laminate. The slit gap is designed in such a way that the layers adjacent to each other have the same thickness. As other film forming conditions, except that the ejection ratio is crystalline resin a composition/resin b composition = 0.25, the transverse stretching temperature is 120°C, the transverse stretching magnification is 3.9 times, and the heat treatment temperature is 230°C, they are set to the same as those in Example 1. The same conditions. The results are shown in Table 1. Compared with Example 1, this is a result of the higher subtractive effect of the B layer of Example 2. We believe that this is because the thickness of the B layer is increased relative to the total thickness, and the phase difference subtraction effect is more exerted than in Example 1.

(Example 4)

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

(Example 5)

Using the same resin as in Example 4, the experiment was performed under the same conditions as in Example 4 except that the longitudinal stretching magnification was 3.5 times and the lateral stretching magnification was 3.3 times. The results are shown in Table 2. As the stretching magnification in the MD direction is increased, although the overall phase difference increases, the subtraction effect is almost unchanged.

(Example 6)

The same resin as in Example 4 was used, and a layer feeder made up of 491 slit plates with one slit was used to converge to form a laminate in which 491 layers were alternately laminated in the thickness direction. However, in the slit plate used, the width of the slit designed to form the thick film layer at both ends is more than twice the width of the slit for forming other thin film layers, and then the minimum layer thickness of the thin film layer is divided into The inclination of the ratio of the maximum layer thickness is designed to be 0.3. Here, the slit widths (gap) are all fixed values, and only the length is changed.

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 obtained laminate was molded under the same conditions as in Example 5. The results are shown in Table 2. As a result, compared with Example 4, the subtractive effect becomes greater.

(Example 7)

In Example 6, the experiment was conducted under all the same conditions except that the longitudinal stretching temperature was increased to 101°C. The results are shown in Table 2. Compared with the embodiment, the longitudinal alignment becomes weaker and the lateral magnification remains unchanged. Therefore, although the overall phase difference increases, the alignment of the B layer remains unchanged, so the subtractive effect is greater.

(Example 8)

In Example 7, the experiment was conducted under all the same conditions except that the lateral stretch magnification was reduced. The results are shown in Table 2. Compared with Example 7, the lateral magnification is lowered, and although the overall phase difference is lowered, the subtraction effect is almost the same as that of Example 7.

(Example 9)

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

(Comparative example 1)

In Example 1, except that resin 5 was used as crystalline resin a and resin 1 was used as resin b, and the longitudinal elongation temperature was 80°C, the longitudinal elongation ratio was 3.3 times, the transverse elongation temperature was 105°C, and the transverse elongation ratio was 3.9. The heat treatment temperature was other than 190°C, and the experiment was carried out in the same way. The results are shown in Table 1. It can be seen that the retardation of the nylon of the surface layer is lower than the total retardation of the laminated film, and the retardation of the PET layer of the inner layer relative to the nylon is increased.

(Comparative example 2)

In Example 1, except that resin 6 was used as crystalline resin a and resin 4 was used as resin b, the longitudinal stretch magnification was changed to 3.3 times, the lateral stretch magnification was changed to 4.1 times, and the heat treatment temperature was changed to 90°C. The same method. It can be seen that the retardation of the inner layer of the film also increases with respect to the retardation of the surface layer.

(Comparative example 3)

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

(Comparative Example 4)

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

It can be seen that if the isophthalic acid copolymer component is less than Comparative Examples 3 and 4, the difference between the retardation of the laminated film and the retardation of the A layer becomes large, and the resin b does not exhibit the subtractive effect.

(Comparative Example 5)

The experiment was performed under the same conditions as in Example 4 except that the longitudinal stretch magnification was changed to 3.3 times and the lateral stretch magnification was changed to 3.5 times. The results are shown in Table 2. Although the overall retardation is reduced, the longitudinal magnification is increased, so there is no effect of subtracting the retardation.

(Comparative Example 6)

In Example 1, all the resins were changed to resin 1, and a single PET film was produced. The stretching conditions were optimized to produce a single film with thickness=40μm, phase difference=1881nm, and alignment angle=0°. The single film was superimposed and the phase difference was measured, thereby investigating the phase difference reduction mechanism. The results are shown in Table 3. When a single PET film is stacked without shifting in the longitudinal direction, the total retardation of the film is the same value as the sum of the two films. On the other hand, when two films are laminated by an angle shifted from the longitudinal direction, it can be seen that when the angle shifts by 45° or more, the retardation at 0° decreases. It can be seen that the greater the shift, the more the retardation of the entire film decreases. From the above results, it can be proved that the phase difference is reduced due to the difference in the main alignment axes of the two superimposed films.

Conduct a theoretical study of this phenomenon (Figure 3). Polyethylene terephthalate-based refractive index ellipsoid, the ellipse equation when only rotating the 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 index of the second layer of the A layer in the X and Y directions are:

Comparing the magnitudes of Nx2 and Ny2, θ≧45° and Nx2≦Ny2, so when viewed from the layer A of the first layer, the birefringence θ≧45° of the second layer is a negative value. Here, if 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, so it is considered that the result is that the retardation of the entire film decreases. That is, it is considered that the phase difference is reduced due to the deviation of the main alignment axis of the two superimposed films. This consideration method also considers the results in two or more different films. Because the main alignment axes of the adjacent films are different, the fast axis and the slow axis are opposite to the A layer. As a result, the phase difference of each layer develops in a decreasing direction, and as a result, it is considered that the total phase difference decreases.

For the multilayer laminate films used in the several examples and comparative examples this time, the physical peeling at the interface of each layer can be used to detect the composition of each layer. To the angle. The total retardation of the film and the retardation of each layer. The results of the alignment angle are shown in Table 4. In Example 4, the alignment angle difference between the A layer and the B layer is about 80°, and it can be seen that the inner layer and the outer layer have a large difference. On the other hand, in Comparative Example 1 and Comparative Example 2, the alignment angles of the inner layer and the outer layer are the same value. From the above results, it can be considered that the total phase difference of the film is reduced due to the different alignment angles of the inner layer and the outer layer of the film produced this time.

(Example 10)

After vacuum drying resin 1 containing 0.04% by weight of agglomerated silica with an average particle size of 2.5μm as a lubricant at 180°C for 3 hours, it was put into a uniaxial extruder and melted at an extrusion temperature of 280°C , And mixing. After passing through a filter with a filtration accuracy of 30μm, it is supplied to the T-shaped mold and formed into a sheet. While applying a 7kV electrostatic imprinting voltage with a wire, the surface temperature is maintained at 25°C on a cast drum. Cool and solidify to obtain an unstretched film. The unstretched film was stretched 3.5 times between the rolls in the longitudinal direction of the film with a longitudinal stretcher at 85°C, and then it was introduced into a tenter that held both ends with clamps. After the film was stretched 3.3 times in the width direction, it was then subjected to a heat treatment at 215°C and a relaxation treatment of about 3% in the film width direction at 150°C to obtain a polyester film with a thickness of 32 μm. Table 5 shows the results of the retardation and alignment angle in the film width direction of the obtained polyester film. The main alignment axis in the film width direction presents 40~60°, showing a uniform alignment angle distribution.

The obtained polyester film has a width of 600mm, and cuts every 1000mm in the longitudinal direction to produce two sheets of 600mm×1000mm each. The winding direction of one sheet is reversed, and the central part, the central part, and the end part are reversed. And end The part overlapped so that the angle between the main alignment axes of the first sheet and the second sheet was 90°±15°, so that the subtractive effect worked, the optical adhesive SK-1478 manufactured by Soken Chemical Co., Ltd. was used. Dry build-up. The thickness of the optical adhesive is 25 μm, and the obtained multilayer laminate film has three layers with a thickness of 89 μm.

The phase difference of the obtained three-layer film was uniform in the film width direction, and all were 50 nm or less, and the subtractive effect was confirmed. The problem of general polyethylene terephthalate used as a conductive substrate for touch panels or an anti-reflective (AR) substrate for displays can be improved, that is, a multilayer laminate film with improved rainbow spots and interference colors can be obtained. In addition, in the touch panel base material, a low phase difference suitable for the GFF sensor type (GFF: touch panel composed of glass cover/ITO/film/ITO/film) where two ITO conductive films are separately provided can be obtained. film.

(Example 11)

Resin 1 was used as resin a and vacuum-dried at 180°C for 3 hours. On the other hand, resin 4 was used as resin b and dried under nitrogen at 80°C, and then put into the uniaxial by the conveying line of each closed system. The extruder and the biaxial extruder are melted at the extrusion temperature of 280°C and 280°C, and then kneaded. Next, use the two discharge holes of the twin-shaft extruder to discharge the vacuum pressure to less than 0.1kPa to remove foreign substances such as oligomers and impurities. After measuring with a gear pump, the discharge ratio (stacked Ratio) is thermoplastic resin A/thermoplastic resin B = 0.7/1, while using the same principle as the laminating device described in Patent No. 4552936, a 255 laminating device is used to form a laminated body in which 255 layers are alternately laminated in the thickness direction. In addition, adjust the length of the slits and the gap between them so that the thickness distribution of the upwardly protruding layer Gap, forming a layered device. For the A layer and the B layer, corresponding to the layer number, an inclined structure whose thickness has a convex layer thickness distribution is formed. The A layer and the B layer are alternately laminated with 255 layers, so that the thickness of the layer near the two surfaces of the laminated film becomes the thinnest. Next, the laminate was supplied to a T-die and formed into a sheet shape. While applying an electrostatic imprinting voltage of 8kV with a wire, it was rapidly cooled and solidified on a casting drum whose surface temperature was maintained at 25°C to obtain an unstretched film. . The unstretched film was stretched 3.2 times in the longitudinal direction of the film with a longitudinal stretcher at 115°C, and then it was introduced into a tenter with a clamp holding both ends, and the film was stretched at 110~140°C. After 4.5-fold lateral stretching in the width direction, stepwise heat treatment at 180°C and 225°C was performed, followed by a relaxation treatment of approximately 3% in the film width direction at 150°C to obtain a multilayer laminate film with a thickness of 13 μm. The thickness of each layer of the obtained multilayer build-up film is in the range of 35 nm to 55 nm. The layer thickness distribution of the obtained multilayer build-up film is an asymptotic convex layer thickness distribution with an average layer thickness of 60 nm in the average layer thickness distribution. The obtained multilayer laminate film has a relative reflectance of 61% at a wavelength of 350 nm as measured by a spectrophotometer. From the center of the film width direction to a position of 250 mm, the alignment distribution of the A layer and the B layer was detected by FT-IR, and the result is shown in Fig. 6. The main alignment axis of the A layer is 120° (300°). In contrast, the main alignment axis of the B layer is 30° (210°). It is confirmed that the A layer is perpendicular to the B layer. In addition, the total retardation Re is 191nm. On the other hand, the difference in refractive index (Nx(1)-Ny(1)) of the outermost surface layer measured by the scalp coupler is determined by the total thickness d(A) of the A layer. The obtained phase difference was 400 nm, and it was confirmed that the phase difference in the in-plane direction at 209 nm was reduced. In addition, the thickness direction retardation Rth at an incident angle of 50° is 450 nm, and it is arranged at On a 42-inch LCD monitor, even if the background color is white, it is a film with no iris spots. Regarding the uneven retardation, the retardation change at 200 mm in the center portion in the width direction of the film was 20 nm.

(Example 12)

Except that the resin 9 was used as the resin b and the longitudinal stretching ratio was changed to 3.5 times, in the same manner as in Example 11, a 255-layer multilayer laminate film was obtained. From the center of the film width direction to the position of 250mm, the main alignment axis of the A layer is 135° (315°). In contrast, the main alignment axis of the B layer is 15° (195°). Confirm that the main alignment axis of the A layer and the B layer is 15° (195°). The angle formed by the alignment shaft is 120°. In addition, the total retardation Re is 150nm. On the other hand, the difference in refractive index (Nx(1)-Ny(1)) of the outermost surface layer measured by the 稜鏡 coupler is determined by the total thickness d(A) of the A layer. The obtained phase difference was 235 nm, and it was confirmed that the phase difference in the in-plane direction was reduced at 55 nm. In addition, the thickness direction retardation Rth at an incident angle of 50° was 398 nm, and it was placed on a liquid crystal display. Even if the background color was set to white, it was a film without iris spots. Regarding the uneven retardation, the retardation change at 200 mm in the center portion in the width direction of the film was 10 nm. The obtained multilayer laminate film has a relative reflectance of 90% at a wavelength of 350 nm as measured by a spectrophotometer.

(Example 13)

Next, except that the resin 10 was used as the resin b, the laminating device was changed to 491 layers, the vertical stretching temperature was changed to 105°C, and the lateral magnification was changed to 3.6 times, the same as in Example 12 was used to obtain 491 layers with a thickness of 15.5 μm. The multi-layer laminated film. The phase difference of the obtained multilayer build-up film was 17 nm. A film with a very uneven retardation in the width direction in which the retardation at the ends in the width direction of the film was 201 nm was obtained. Obtained from Example 13 The distribution of the phase difference and the alignment angle of the obtained multilayer laminate film in the film width direction is shown in Fig. 7. Fig. 7(a) is the phase difference distribution, and Fig. 7(b) is the alignment angle distribution. In addition, as described in Fig. 4(a), the measurement position (X) in the width direction of the film is expressed by the relative position (±X/W) divided by the half value (W) of the full width of the film. The retardation values are all below 400 nm, so no rainbow spots are observed, and the quality is good. However, when observed under crossed Nicolas, the contrast of brightness is different in the film width direction.

(Example 14)

Except that the longitudinal stretching ratio of Example 13 was changed to 3.2 times, in the same manner as in Example 13, a multilayer laminate film of 491 layers with a thickness of 15.5 μm was obtained. Because the resin b is not aligned, the subtractive effect of the phase difference is only about 6 nm. On the other hand, no rainbow spots were observed.

(Example 15, Comparative Example 7)

Using the multilayer laminate film obtained in Example 13, according to the relationship between (a) phase difference subtraction and (b) phase difference addition described in Figure 5, a full-width multilayer laminate film was cut into In the half, thin-film lamination is performed 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 with the MD direction reversed. In the full width direction, all the retardation is below 40nm, achieving no rainbow spots and forming a uniform low retardation aggregate multi-layer laminated film. It was confirmed that these films are suitable for applications that require two GFF type ITO base films. On the other hand, Fig. 8(b) shows the phase difference distribution when the MD direction is aligned and folded and laminated. All the phase differences increase, and it can be seen that the phase difference unevenness in the width direction becomes larger. At the end, the phase difference is greater than 400 nm, and rainbow spots are found.

(Example 16)

The collective multilayer laminate film obtained in Example 15 was cut at 4 points at equal intervals from the film width direction, and the films were laminated with an adhesive to evaluate the retardation. As a result, the phase difference SRe was 75 nm. On the other hand, if the sum of the retardation of the multilayer film at 8 points in the film width direction, that is, the value of formula (3) (n=8), it is 826 nm, and the subtractive effect of the collective multilayer film can be confirmed. These films are good films that can be used as optical films without interference colors.

(Example 17)

Except that the resin 10 was used as the resin b, the longitudinal stretching temperature was changed to 110° C., and the longitudinal magnification was changed to 3.3 times, in the same manner as in Example 11, a 255-layer multilayer laminate film was obtained. Samples were taken from the center of the film width direction and a position of 200 mm, and then liquid crystal materials were applied on the multilayer laminate films to form a C layer.

烷中，並添加偶氮二異丁腈作為反應起始劑，於70℃下進行聚合24小時，得到聚合物。將其溶解於四氫呋喃/碳酸丙酯混合溶液，作成固體成分濃度25重量%的溶液。以旋轉塗布裝置塗布成厚度為2μm後，進行預備加熱，得到感光性液晶高分子。使用格蘭-泰勒稜鏡，從薄膜之塗布膜面的法線方向傾斜60度以上的入射角度，進行經直線偏光的紫外線照射，之後，於120℃下進行熱處理，形成包含具有正C板特性之液晶材料的C層。C層之厚度方向的折射率N_Z為1.69，面內方向的折射率N_X,及N_Y為1.56，確認其為 正C板。所得到之厚度方向相位差的相減效果整理於表7。形成C層前，在從斜向的正交尼寇觀察中發現著色，但以KOBRA測量確認薄膜寬度方向中央部及200mm位置皆為厚度方向的相位差減少50nm左右。根據二次函數近似，90°下厚度方向相位差具有208nm左右的減少效果。在正交尼寇下的觀察中亦為無色，成功得到適合顯示器等的複合多層積層薄膜。塗布C層前後的厚度方向相位差的結果顯示於表7。亦確認C層之主配向軸Φc與多層積層薄膜之主配向軸Φab所形成的夾角|Φc-Φab|在50°~90°的範圍。 The C layer system synthesizes 4-(6-hydroxyhexyloxy) cinnamic acid, and then adds methacrylic acid in the presence of p-toluenesulfonic acid to carry out an esterification reaction to obtain compound 1. Dissolve 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 with a solid content concentration of 25% by weight. After coating with a spin coater to a thickness of 2 μm, preliminary heating was performed to obtain a photosensitive liquid crystal polymer. Using Glan-Taylor 稜鏡, the incident angle of 60 degrees or more inclined from the normal direction of the coating film surface of the film is irradiated with linearly polarized ultraviolet rays, and then heat-treated at 120 ℃ to form a positive C plate. The C layer of liquid crystal material. _{The refractive index N Z in} the thickness direction of the C layer is 1.69, and the refractive index N _X, and N _{Y in the in-} plane direction are 1.56, confirming that it is a positive C plate. The obtained subtraction effects of the thickness direction retardation are summarized in Table 7. Before the formation of the C layer, coloration was observed in the oblique cross-Nicol observation. However, it was confirmed by KOBRA measurement that both the central part in the width direction of the film and the 200 mm position were in the thickness direction, and the retardation decreased by about 50 nm. According to the quadratic function approximation, the thickness direction retardation at 90° has a reduction effect of about 208 nm. It was also colorless in the observation under crossed Nicolas, and successfully obtained a composite multi-layer laminate film suitable for displays. Table 7 shows the results of the thickness direction retardation before and after application of the C layer. It is also confirmed that the angle between the main alignment axis Φc of the C layer and the main alignment axis Φab of the multilayer film |Φc-Φab| is in the range of 50°~90°.

Claims (13)

A multilayer laminated film in which at least 3 layers are alternately laminated with a layer A containing a biaxially oriented crystalline resin a and a layer B containing a resin b with a lower crystallinity than the crystalline resin a, It is characterized in that: the resin b is made of one or more components selected from the group consisting of isophthalic acid, isosorbide, stilbene, bisphenol A, and cyclohexane dimethanol to the crystalline resin a. Polymerized copolymer. The main alignment axis of the A layer and the B layer are different. When the phase difference from the surface layer to the kth layer is set to Re(k) and the total number of layers is set to n, the multilayer laminate film The total phase difference Re satisfies formula (1) and formula (2);

(2) Re≦400nm. The multilayer laminate film of claim 1, wherein, on the outermost surface of the film, the refractive index in the direction giving the maximum refractive index in the in-plane direction is set to Nx(1), and the refractive index in the direction perpendicular to it is set to Ny (1) When the total thickness of the layer composed of the same resin as the outermost surface layer is set to d(A), and the total retardation of the multilayer laminate film is set to Re, it satisfies the formula (5); (5) Re- (Nx(1)-Ny(1))×d(A)<0. The multilayer laminate film of claim 1 or 2, wherein the crystalline resin a is selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate Kind of. The multilayer laminate film of claim 1 or 2, wherein the glass transition temperature of the crystalline resin a is lower than the glass transition temperature of the resin b. For example, the multi-layer laminated film of claim 1 or 2, which is a multi-layer laminated film whose main alignment axis has an inclination of 10 to 80° with respect to the longitudinal direction of the multi-layer laminated film, wherein the main axis of the A layer contained in the multi-layer laminated film is The angle formed by the alignment axis and the main alignment axis of the B layer is 60 to 120°. Such as the multi-layer laminated film of claim 1 or 2, wherein the phase difference in the width direction of the film is not all 50nm/200mm or less. Such as the multi-layer laminated film of claim 1 or 2, wherein the reflectance at a wavelength of 350 nm is 20% or more. Such as the multilayer laminated film of claim 1 or 2, which is used as an optical film. A composite multi-layer laminated film, which is a multilayer laminated film comprising a layer A containing a crystalline resin a and a layer B containing a resin b whose crystallinity is lower than the crystalline resin a. At least 3 layers are alternately laminated on a multilayer laminated film containing The composite multi-layer laminated film of the C layer of the liquid crystal material is characterized in that the resin b is selected from the group consisting of isophthalic acid, isosorbide, fen, bisphenol A, and cyclohexane dimethanol. A copolymer of more than one component of crystalline resin a, the main alignment axis of the A layer and the B layer are different, the total thickness direction retardation Rth' of the composite multilayer film and the total of the multilayer film The thickness direction retardation Rth satisfies the formula (4), and _{the relationship between the refractive index N Z in} the thickness direction of the C layer and the refractive index N _X and N _Y in the in-plane direction satisfies the formula (6) and the formula (7); (4) )Rth'<Rth (6)N _Z >N _X, N _Y (7)N _Z ≧1.6. Such as the composite multilayer laminated film of claim 9, 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 has a relationship of 50° to 90°. For example, the composite multilayer laminate film of claim 9 or 10 is used as an optical film. A collective multi-layer laminated film, which is a first multi-layer laminated film and a second multi-layer laminated film comprising at least two layers of layer A containing a crystalline resin a and a layer B containing a resin b having a lower crystallinity than the crystalline resin a The film is sequentially stacked on the k-th multi-layer film to form an aggregate multi-layer laminated film, characterized in that: the resin b is selected from the group consisting of isophthalic acid, isosorbide, stilbene, bisphenol A, and cyclohexane dimethanol A copolymer composed of one or more components in the component group of the crystalline resin a, the main alignment axis of the A layer and the B layer are different, and at least one set of two or more multi-layer laminated films The main alignment axis is vertical or is in a relationship of 60 to 120°. When the phase difference of the multilayer film in the k-th layer is set to SRe(k) and the number of all multilayer films is set to n, it is regarded as an aggregate of the multilayer film The total phase difference SRe satisfies formula (3); k is a natural number;

For example, the collective multilayer laminate film of claim 12 is used as an optical film.

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