JP6880621B2 - Thermoplastic resin film - Google Patents

Description

The present invention relates to a thermoplastic resin film and an anti-counterfeit sheet using the same.

Films that change color depending on the viewing angle may be used for decoration of home appliances, arts and crafts, and forgery prevention sheets. In recent years, in order to produce various expressions, there is a demand for a film having a highly accurate color change pattern.

There is a method using embossed hologram technology as a typical method for obtaining a film whose color changes depending on the viewing angle. By applying fine optical unevenness processing to the film surface, it is possible to change the color to rainbow colors depending on the viewing angle, but the construction method is complicated, and there are problems in cost and mass productivity.

As another means for achieving a film whose color changes depending on the angle, a hologram sheet in which a pseudo hologram is formed by screen printing and the pattern changes depending on the observation angle to simplify the manufacturing process has been proposed (see Patent Document 1). ). Further, there is known a light interference multilayer film in which a large number of two kinds of resins having different refractive indexes are alternately laminated and a specific wavelength is reflected by structural light interference between the layers. In this method, a multilayer laminated film has been proposed in which the wavelength of the reflected light is designed to be close to the primary color of the light by the reflection of the selective wavelength, and the reflection peak wavelength is greatly shifted with respect to the incident angle ( See Patent Document 2).

Japanese Unexamined Patent Publication No. 2014-12388 Japanese Unexamined Patent Publication No. 2005-59332

The hologram sheet described in Patent Document 1 has a convex curved surface surface obtained by printing halftone dots on a vapor-deposited paper or the like having a halftone base printing layer on the surface twice at different angles in the range of 0.2 to 1 °. A pseudo-hologram pattern is formed by forming dots for printing on the upper surface. However, since a vapor-deposited paper, mirror ink, or the like is required for the base material in order to realize high reflection, there is a problem that the sheet contains metal and cannot be applied to a member that requires recyclability and electromagnetic wave transmission.
In the method described in Patent Document 2, although the color tone changes greatly depending on the angle, the color tone is close to a single color because it is reflected in a narrow band, and a deep color tone is realized and a high-class feeling and counterfeiting due to high reflection in the visible light band are achieved. There was a problem that the expression of the unique color required for prevention could not be achieved.

Therefore, the present invention solves the above-mentioned problems of the prior art, and provides a thermoplastic resin film that highly reflects visible light, has a large coloration when viewed from the front, and has a remarkable change in saturation with a slight change in angle. It is in.

The present invention employs the following means in order to solve such a problem. That is,
The average reflectance in the wavelength band 400-750 nm measured at an incident angle of 12 ° is 30% or more, and the spectral reflectance measured at an incident angle of 12 ° and 30 ° is a color tone calculated using the formula specified in JISZ8781. The values (a ^* [12 °], b ^* [12 °]), (a ^* [30 °], b ^* [30 °]) satisfy the following equation (i) .
It has a layer containing a thermoplastic resin A as a main component (A layer) and a layer containing a thermoplastic resin B as a main component (B layer), and the A layer and the B layer are adjacent to each other. The total number of layers and the B layer is 200 or more,
The thermoplastic resin A is a crystalline thermoplastic resin, and the thermoplastic resin B is an amorphous thermoplastic resin.
The crystalline thermoplastic resin is a crystalline polyethylene terephthalate or crystalline polyethylene naphthalate, the amorphous thermoplastic resin, Ru spiroglycol copolymerized polyethylene terephthalate, and / or cyclohexane dimethanol copolymerized polyethylene terephthalate der It is a thermoplastic resin film characterized by the above .
Equation (i) √ {(a ^* [12 °] -a ^* [30 °]) ² + (b ^* [12 °] -b ^* [30 °]) ² } ≧ 25
(The value in [] indicates the measured incident angle)

According to the present invention, it is possible to obtain a thermoplastic resin film that highly reflects visible light, has a large coloration when viewed from the front, and has a remarkable change in saturation with a slight change in angle.

The figure which shows the design layer thickness of Examples 1-6 and Comparative Examples 1-5 The figure which shows the design layer thickness of Example 7. The figure which shows the design layer thickness of Examples 8 and 9. The figure which shows the design layer thickness of Example 10. The figure which shows the design layer thickness of the comparative example 6 An example of a block diagram of a feed block used in the present invention Structural drawing of slit plate and slit Cross-sectional configuration of the slit

The thermoplastic resin film of the present invention needs to have an average reflectance of 30% or more in a wavelength band of 400 to 750 nm measured at an incident angle of 12 °, which is determined by a measurement method described later. It is preferably 40% or more, and more preferably 50% or more. The angle of incidence in the present invention is such that the angle parallel to the thickness direction of the film is 0 ° and the angle perpendicular to the thickness direction of the film is 90 °. In general, the reflectance of a film utilizing interference reflection tends to be higher when the incident angle is closer to 90 °. Therefore, by setting the average reflectance in the wavelength band 400-750 nm measured at an incident angle of 12 ° to 30% or more, a film having high reflectance at a wide angle can be obtained. When the average reflectance in the wavelength band 400-750 nm is high, the saturation is high, so that the saturation change when the incident angle is changed tends to be large. When the average reflectance measured at an incident angle of 12 ° is less than 30%, the saturation becomes low, and the change in saturation when the incident angle changes becomes small. The saturation is a numerical value indicating the colored size represented by ^{√ (a * 2} + b ^{* 2).}

^{The thermoplastic resin film of the present invention has a color tone value (a *} [12 °) calculated by using a calculation formula specified in JISZ8781 for spectral reflectance measured at incident angles of 12 ° and 30 °, which are obtained by a measurement method described later. ], B ^* [12 °]), (a ^* [30 °], b ^* [30 °]) must satisfy the following equation (i).
Equation (i) √ {(a ^* [12 °] -a ^* [30 °]) ² + (b ^* [12 °] -b ^* [30 °]) ² } ≧ 25
In the present invention, √ {(a ^* [12 °]-a ^* [30 °]) ² + (b ^* [12 °]-b ^* [30 °]) ² } is subsequently changed to ΔC ^* (angle-dependent saturation). Difference) may be called. ΔC ^* is an index showing the degree of change in saturation depending on the viewing angle (angle-dependent saturation difference). By ^{setting ΔC *} within the above range, the color tone changes with a slight change in the incident angle of light, and it is possible to produce a color and a sense of quality that cannot be achieved by conventional technology, and it can be applied to anti-counterfeit sheets. It is possible to achieve a unique color. ΔC ^* is preferably 30 or more, more preferably 40 or more, and preferably 90 or less. When ΔC ^* is less than 25, the angle dependence of the saturation change becomes small, and the color change can be achieved by the conventional technique.

^{In the thermoplastic resin film of the present invention, it is preferable that a *} [12 °] and b ^* [12 ° ] at an incident angle of 12 ° determined by the measurement method described later satisfy the following formula (ii).
Equation (ii) √ (a ^* [12 °] ² + b ^* [12 °] ² ) ≧ 30
In the present invention, √ (a ^* [12 °] ² + b ^* [12 °] ² ) may be referred to as C ^{* (saturation) hereafter.} By ^{setting C *} to 30 or more, it is possible to obtain a film having a large color and a high design. C ^* is preferably 40 or more, and more preferably 50 or more. When C ^* is less than 30, in addition to not being able to achieve high design, the change in ΔC ^* may be small even when the incident angle is changed. In the measurement of spectral reflectance, an angle of about 10 ° is the minimum measurement angle, and the saturation is closest to that when viewed from the front. Therefore, in the present invention, the measured value of the incident angle of 12 ° is visually recognized from the front. It may be the value when it is done.

The thermoplastic resin film of the present invention preferably has a haze of 0.1% or more and 2.0% or less. It is preferably 0.1% or more and 1.5% or less, and more preferably 0.1% or more and 1.0% or less. If the haze of the film exceeds 2.0%, the visibility of the printed matter may decrease when the print layer is provided on the back surface of the film sheet.

It is preferable that the thermoplastic resin film of the present invention does not undergo delamination in an adhesion test by a cross-cut method according to JIS K5600. When delamination occurs by the cross-cut method, delamination may occur due to stress during cutting in the film processing process, and the processing yield may decrease.

The thermoplastic resin film of the present invention, _R 80 obtained by the following formula from the reflectance in the wavelength band 400-750nm, measured at an incident angle of 12 ° as determined by a measuring method described later (iii), formula (iv), R ₂₀ is obtained, and the wavelength that exceeds the reflectance _{of R 80 in the lowest wavelength band is λ 80 on} the low wavelength side, and the wavelength _{closest to λ 80} that exceeds the reflectance _{of R 20} on the low wavelength side from _{λ 80} on the low wavelength side is the low wavelength. The side λ ₂₀ is set, the wavelength band of the low wavelength side λ ₈₀ − low wavelength side λ ₂₀ is the low wavelength side λ ₈₀ −λ ₂₀ , and the wavelength _{exceeding the reflectance of R 80 in} the highest wavelength band is the high wavelength side λ ₈₀ , high. a wavelength closest to lambda ₈₀ that exceeds the reflectance R ₂₀ from wavelengths lambda ₈₀ with high wavelength side and high wavelength side lambda _20, the high wavelength side lambda _{20 -} higher wavelength side lambda ₂₀ wavelength bands of high wavelength side lambda ₈₀ When −λ ₈₀ is set, the wavelength band of the low wavelength side λ ₈₀ −λ ₂₀ and the high wavelength side λ ₂₀ −λ ₈₀ is preferably 65 nm or less. It is more preferably 55 nm or less, still more preferably 45 nm or less. When the values of the low wavelength side λ _80- λ ₂₀ and the high wavelength side λ _20- λ ₈₀ become small, the rise of the reflection reaching from the low reflection region to the high reflection region in the wavelength band 400-750 nm, and the reflection The fall of the reflection from the high region to the low reflection region changes sharply at short wavelength intervals. By sharpening the rising and falling edges of the reflection, it is possible to selectively reflect only the target wavelength, and ΔC ^* becomes large with a slight change in the incident angle.
Equation (iii) R ₈₀ = {(maximum reflectance-minimum reflectance) x 0.8} + minimum reflectance (%)
Equation (iv) R ₂₀ = {(maximum reflectance-minimum reflectance) x 0.2} + minimum reflectance (%)
The thermoplastic resin film of the present invention has a layer made of a thermoplastic resin A (hereinafter referred to as a layer A) and a layer made of a thermoplastic resin B containing an amorphous resin (hereinafter referred to as a layer B), and has a thickness. It is preferable that a total of 200 or more layers are laminated alternately in the direction. A structure in which 300 or more layers are alternately laminated in the thickness direction is more preferable, and a structure in which 400 or more layers are alternately laminated in the thickness direction is more preferable. In the case of a stack of less than 200 layers, only a part of the wavelengths of visible light are reflected, and the reflection is close to a single color, so that high designability due to color depth and high reflection may not be achieved.

In the thermoplastic resin film of the present invention, the thickness of the outermost layers on both sides is preferably 1 μm or more and 10 μm or less. More preferably, it is 2 μm or more and 7 μm or less. If it is less than 1 μm, uneven stacking may occur due to poor stacking, the rising and falling bands of reflection may become wide, and ΔC ^* may become small. If it exceeds 10 μm, delamination may easily occur in the vicinity of the thick film layer on the surface layer.

The thermoplastic resin film of the present invention preferably has one or more layers having a thickness of 2 μm or more and 6 μm or less as an inner layer. More preferably, it is 3 μm or more and 4 μm or less. If it is less than 1 μm, uneven stacking may occur due to poor stacking, and the target optical performance may not be obtained and ΔC ^* may become small. If it exceeds 6 μm, delamination may easily occur near the inner thick film layer.

In the thermoplastic resin film of the present invention, in a thin film layer having a layer thickness of less than 1 μm, the difference in thickness between adjacent layers in each of the A layer and the B layer continuously increases or decreases monotonically within a range of 50 nm or less. It is preferable to have two or more steps of the inclined structure. If it does not have a two-stage or more inclined structure, a slight stacking defect will occur in a very small number of layers, and if it deviates from the design value, there will be no layers of the same thickness in other parts, so reflection will occur. The rising and falling bands may become wide and ΔC ^* may not be small. As an example of a preferable layer structure of the thermoplastic resin film in the present invention, a diagram showing the design layer thickness will be described. FIG. 1 shows a film in which layers composed of two types of thermoplastic resins (hereinafter, also referred to as resin A and resin B) are alternately laminated in the thickness direction, and layers A and B are arranged in each layer order (hereinafter referred to as layer number). It is a figure plotted against. The layer thickness corresponds only to the integer layer number in the figure, the layer A made of the crystalline thermoplastic resin A corresponds to the odd number, and the layer B made of the thermoplastic resin B containing the amorphous resin corresponds to the layer B. Corresponds to even numbers. Further, the thick film layer is preferably formed of an A layer made of a resin A which is a crystalline resin. The same applies to FIG. Further, the thickness of the inner layer having a thickness of 2 μm or more and 6 μm or less is likely to occur in the portion where the layer structure changes from decrease to increase and from increase to decrease, which causes a wide rise and rise band of reflection. By providing the film layer at the above-mentioned location, the thick film layer can absorb the shear stress generated in the extrusion process during manufacturing, which causes poor lamination. When the thick film layer of the inner layer is less than 2 μm, the shear stress caused by the stacking failure at the place where the layer structure changes from decrease to increase and from increase to decrease is not sufficiently absorbed, so that the stacking defect can be suppressed. However, since the reflection of light at a specific wavelength is different from the design value, ΔC ^* may become small with a slight change in angle. When the inner thick film layer exceeds 6 μm, the elastic modulus differs between the thick film layer made of crystalline resin A and the portion other than the thick film layer. Therefore, when shear stress is applied in the thickness direction during cutting in processing, the thick film layer Stress is concentrated in the vicinity, and delamination may easily occur. FIG. 3 shows a structure in which the number of layers in FIG. 1 is 349 layers, and FIG. 4 shows a structure in which the number of layers in FIG. 1 is 249 layers. FIG. 5 shows a structure in which the number of layers of FIG. 1 is 149, and since the number of layers is small, reflection is performed in a narrow wavelength band, so that the color tone is close to a single color, and the number of reflection layers is small, so that the wavelength It may not be possible to increase the average reflectance in the band of 400 to 700 nm to 30% or more.

Further, in the present invention, for convenience, the layer thickness structure of FIGS. 1, 3, 4 and 5 is referred to as a two-stage inclined structure, and the layer thickness structure of FIG. 2 is referred to as a three-stage inclined structure. Here, the "two-stage inclined structure" referred to in the present invention refers to a structure that can be approximated by two monotonically increasing curves and / or monotonically decreasing curves.

The two types of resins, the crystalline thermoplastic resin A and the thermoplastic resin B containing the amorphous resin in the present invention, may be a copolymer or a mixture of two or more types of resins. Above all, it is particularly preferable to use a polyester resin. The crystallinity here means that the heat of fusion is 5 J / g or more in the differential scanning calorimetry (DSC). On the other hand, amorphous means that the amount of heat of fusion is less than 5 J / g.

As the polyester resin, a polyester obtained by polymerization of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a monomer containing a diol as a main component is preferable. Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-. Examples thereof include diphenyldicarboxylic acid, 4,4′-diphenyletherdicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid and the like. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecandioic acid, cyclohexanedicarboxylic acid and their ester derivatives. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid having a high refractive index are preferable. Only one type of these acid components may be used, two or more types may be used in combination, and an oxyacid such as hydroxybenzoic acid may be partially copolymerized. Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. , 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-hexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4-) Hydroxyethoxyphenyl) propane, isosorbate, spiroglycol and the like can be mentioned. Of these, ethylene glycol is preferably used. Only one kind of these diol components may be used, or two or more kinds may be used in combination.

Among the polyesters, polyethylene terephthalate and its copolymer, polyethylene naphthalate and its copolymer, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, and polyhexamethylene terephthalate and its copolymer. It is preferable to use a polymer, polyhexamethylenenaphthalate, a copolymer thereof, or the like.

As a preferable combination of the resin A and the resin B selected from the thermoplastic resins, it is preferable to use a resin containing the same basic skeleton as one of the resins. Here, the "basic skeleton" referred to in the present invention refers to a repeating unit constituting a resin. For example, when one resin is polyethylene terephthalate, ethylene terephthalate is the basic skeleton, and the other resin in this case. Examples thereof include a polymer (copolymer) composed of an ethylene terephthalate unit and a cyclohexane 1,4-dimethylene terephthalate unit. As another example, when one of the resins is polyethylene, ethylene is the basic skeleton. When resins having the same basic skeleton are used, problems such as delamination are less likely to occur in the film formation of the thermoplastic resin film.

As the crystalline thermoplastic resin A, polyethylene terephthalate or polyethylene naphthalate is preferably used from the viewpoint of imprint resistance (dent resistance) and the strength of the film itself.

The amorphous resin of the thermoplastic resin B containing the amorphous resin contains isophthalic acid, naphthalenedicarboxylic acid, diphenylic acid, cyclohexanedicarboxylic acid, or spiroglycol, from the viewpoint of suppressing an increase in refractive index. It is preferable to use a copolymer of the above resin A containing cyclohexanedimethanol, bisphenoxyethanol fluorene, and a bisphenol A component mixed with the above resin A or used alone.

FIG. 6 shows an example of a feed block which is a suitable embodiment for obtaining a thermoplastic resin film having an inclined structure in the present invention. The feed block is a laminating device for laminating two types of resin A and resin B in multiple layers, and details will be described below. In FIG. 6, member plates 6 to 16 are stacked in this order to form a feed block 17.

The feed block 17 of FIG. 6 has five resin introduction ports derived from the resin introduction plates 7, 9, 11, 13, and 15. For example, the resin A is introduced from the introduction ports 18 of the resin introduction plates 7, 11, and 15. The resin B is supplied and the resin B is supplied from the introduction port 18 of the resin introduction plates 9 and 13. Then, the slit plate 8 receives the supply of the resin A from the resin introduction plate 7 and the resin B from the resin introduction plate 9, and the slit plate 10 supplies the resin A from the resin introduction plate 11 and the resin B from the resin introduction plate 9. The receiver and the slit plate 12 receive the supply of the resin A from the resin introduction plate 11 and the resin B from the resin introduction plate 13, and the slit plate 14 supplies the resin A from the resin introduction plate 15 and the resin B from the resin introduction plate 13. Will receive.

Here, the type of resin introduced into each slit plate is determined by the positional relationship between the bottom surface of the liquid reservoir 19 in the resin introduction plates 7, 9, 11, 13, and 15 and the end portion of each slit in the slit plate. Slit. That is, as shown in FIG. 6, the ridge line 20 at the top of each slit in the slit plate has an inclination with respect to the thickness direction of the slit plate (FIGS. 7 (b) and 7 (c)). However, as shown in FIG. 7A, the slit width for forming the thick film layer located at both ends of the slit plate is 2 of the slit width for forming another thin film layer from the viewpoint of preventing the thin film layer from being destroyed. It needs to be more than double. Here, the slit width forming the other thin film layer is an average value of the widths of the slit portions forming the thin film layer in at least one slit plate. More preferably, it is 3 times or more. In particular, the slits corresponding to the outermost surface layers of the films of the slit plate 8 and the slit plate 14 need to be 10 times or more the width of the slit into which the resin A flows and forms another thin film layer. At this time, by continuously arranging the slits into which the resin A flows, the total width can be made 10 times or more the slit width forming another thin film layer. In this way, by providing a thick film layer at the place where the resin sent from the feed block joins and at the place corresponding to the boundary with the wall surface of the pipe in the path from the feed block to the base, the layer thickness distribution changes immediately after the joining. Since it is possible to prevent the resin speed from fluctuating in the multi-layer flow near the piping, the bandwidth of the rising and falling edges of the reflection is narrow without breaking the stacking ratio, and ΔC ^{* with a slight change in angle.} It is possible to obtain a thermoplastic resin film in which the amount of change is large.

Then, as shown in FIG. 8, the height of the bottom surface of the liquid reservoir 19 in the resin introduction plates 7, 9, 11, 13, 15 (13, 15 are omitted from FIG. 8 because they have a repeating structure) is described above. It is located at a height between the upper end 21 and the lower end 22 of the ridge line 20. As a result, the resin was introduced from the liquid reservoirs 19 of the resin introduction plates 7, 9, 11, 13, and 15 from the side where the ridge line 20 was raised (23 in FIG. 8), but the ridge line 20 was lowered. From the side, the slit is closed and no resin is introduced. Thus, since the resin A or B is selectively introduced for each slit, the flow of the resin having a laminated structure is the slit plates 8, 10, 12, 14 (12, 14 are omitted from FIG. 8 because they have a repeating structure). It is formed inside and flows out from the outlet 24 below the slit plates 8, 10, 12, and 14.

As for the shape of the slit, it is preferable that the slit area on the side where the resin is introduced and the slit area on the side where the resin is not introduced are not the same. With such a structure, the flow rate distribution on the side where the resin is introduced and the side where the resin is not introduced can be reduced, so that the stacking accuracy in the width direction is improved. Further, it is preferable that (slit area on the side where the resin is not introduced) / (slit area on the side where the resin is introduced) is 0.2 or more and 0.9 or less. More preferably, it is 0.5 or less. Further, it is preferable that the pressure loss in the feed block is 1 MPa or more. Further, it is preferable that the slit length (the longer of the slit lengths in the Z direction in FIG. 6) is 20 mm or more. On the other hand, the gap width of the slit is preferably 0.3 mm or more, more preferably 0. It is 5 mm or more and 3 mm or less.

By adjusting the width and length of the slits in this way, it is possible to control the thickness of each layer and obtain a thermoplastic resin film having an inclined structure. Further, in each slit, the slit gap width is preferably in the range of -3% to + 3% of the target value. More preferably, it is in the range of -2% to + 2%. When the slit gap width is in the range of -3% to + 3% of the target value, it is possible to prevent a local increase or decrease in the density of the layer thickness. The slit is preferably manufactured by wire electric discharge machining from the viewpoint of requiring high processing accuracy in which the width and length are finely adjusted.

It is also preferable to have a manifold portion corresponding to each slit plate. Since the flow velocity distribution in the width direction (Y direction in FIG. 6) inside the slit plate is made uniform by the manifold portion, the stacking ratio in the width direction of the laminated films can be made uniform, and a large-area film can be made uniform. However, it is possible to stack the films with high accuracy, and the reflectance in the film width direction can be controlled with high accuracy. Further, it is preferable that a second manifold having a stacking direction dimension larger than the slit gap is provided in all of the slit width directions in the portion communicating from the manifold to each slit. Further, it is preferable that the second manifold is twice or more the slit gap. In addition, it is preferable that the second manifold is inclined in the downstream direction as the distance from the manifold of the resin introduction plate communicating with the slit is increased. With such a structure, the molten material easily flows into the slit in the portion far from the manifold of the resin introduction plate, and the flow rate difference between the near side and the far side of the first manifold of the slit becomes small, so that the flow rate difference in the slit width direction becomes small. The flow rate of the molten material becomes uniform. Further, it is more preferable to supply the resin from one liquid reservoir to two or more slit plates. In this way, for example, even if the flow rate distribution is slightly generated inside the slit plate in the width direction, it is further laminated by the merging device described below, so that the lamination ratio is made uniform in total. It is possible to reduce unevenness in the higher-order reflection band.

The polymer passing through the slit is generally represented by the formula (v).

That is, considering that the pressure in the liquid reservoir is made uniform and the pressure drop ΔP is constant, the flow rate Q corresponding to the layer thickness of one layer can be easily adjusted by adjusting the size of one slit. it can. In this device, since the thickness of each layer can be adjusted by the slit shape (length, width), it is possible to achieve an arbitrary layer thickness. For example, an achievement method when the structure is as shown in FIG. 1 will be described. In this case, the slit plates are composed of two sheets, and the slit lengths of the individual slit plates have a distribution of slit lengths that increase and decrease monotonically, and are between adjacent slit plates (here, monotonous). Distribution of the length and width of at least 10 or more slits arranged in front and behind, centering on the slits forming the thick film layer that serves as the joint between the layers at the points where the increase is reduced or the monotonous decrease is changed to the increase). However, it is achieved by designing the front and back to be the same.

Q: Resin flow rate t: Slit width W: Slit depth μ: Resin viscosity L: Slit length ΔP: Pressure drop The resin flowing out from each slit plate is a merging device arranged directly below the feed block in FIG. Is merged as one laminated flow. After that, the molten resin flow is filled in the manifold portion inside the T-die, further widened, and then extruded into a sheet shape from the die slit. At this time, the sheet width direction dimension of an arbitrary cross section perpendicular to the flow path direction in the flow path connecting the feed block and the mouthpiece is W, the sheet thickness direction dimension is T, and the sheet width direction dimension of the discharge port of the mouthpiece. Is Wd, and the dimension in the minimum sheet thickness direction of the outermost layer of the laminated body is L, it is preferable that both the relations of the formula (vi) and the formula (vii) are satisfied.

In order for the thermoplastic resin film to reflect only the design wavelength in the wavelength band of 400-750 nm, it is necessary to design the layer thickness of each layer based on the following formula (viii). The thermoplastic resin film in the present invention can reflect / transmit light, and its reflectance can be controlled by the difference in refractive index between the resin A and the resin B and the number of layers.
Equation (viii) 2 × (na ・ da + nb ・ db) = λ
na: In-plane average refractive index of the layer made of crystalline thermoplastic resin A nb: In-plane average refractive index of the layer made of thermoplastic resin B containing amorphous resin da: Layer thickness of the layer made of resin A (Nm)
db: Layer thickness (nm) of the layer made of resin B
λ: Main reflection wavelength (primary reflection wavelength)
A layer, in-plane average refractive index of the layer B _(n a, _{n b)} the value of the magnitude of the oriented film of a single layer 5 mm (width direction) × 20 mm (longitudinal direction) × 0.5 mm (thickness direction) It is obtained by measuring the refractive index of the film at a temperature of 23 ° C. and a wavelength of 589 nm five times with an Abbe refractive index meter and calculating the average value thereof.

In the thermoplastic resin film of the present invention, it is necessary to control the unevenness of lamination immediately after the resin A and the resin B are merged by the feed block in order to make the lamination of the resins A and B as designed. Since the melt viscosities of the resin A and the resin B merged at the feed block are different, the stacking unevenness occurs near the interface between the resin A and the resin B, and the stacking unevenness grows before the mouthpiece is discharged, so that the layer thickness changes from the design. However, it may not be possible to achieve reflection in the desired wavelength band. In order to achieve high reflection, a PET resin may be used for the resin A, and a resin obtained by copolymerizing spiroglycol (SPG) and cyclohexanedicarboxylic acid (CHDC) as a low viscosity resin may be used for the resin B, but it is common. In the temperature range of 270 to 290 ° C., which is a moderate melting temperature, the melt viscosity of the resin A may be low, and the shear stress caused by the difference in viscosity may occur in the distribution of the shear stress in the layer of the resin B. In order to reduce the shear distribution of the resin B in the layer due to the resin A, the viscosity of the resin A is low, and increasing the viscosity of the resin B is preferable because uneven lamination can be suppressed.

In the thermoplastic resin film of the present invention, the difference between the in-plane average refractive index of the A layer and the in-plane average refractive index of the B layer of the thermoplastic resin film is preferably 0.055 or more and 0.120 or less. More preferably, it is 0.060 or more and 0.115 or less. If the difference in the in-plane average refractive index is less than 0.055, sufficient reflectance may not be obtained and high designability may not be achieved.

The thermoplastic resin film of the present invention preferably has an easy-adhesion layer made of an acrylic / urethane copolymer resin and two or more kinds of cross-linking agents provided on at least one side of the thermoplastic resin film. When a printing layer or a hard coat layer is applied to a thermoplastic resin film, if an easy-adhesion layer is not provided on the treated surface, the adhesion at the interface may decrease. Further, when the printing layer and the hard coat layer are applied to both sides of the thermoplastic resin film, it is preferable that the easy-adhesion layer is provided on both sides.

As the acrylic / urethane copolymer resin constituting the easy-adhesion layer preferably used in the present invention, the acrylic monomer is, for example, an alkyl acrylate (as an alkyl group, methyl, ethyl, n-propyl, n-butyl, isobutyl, t- Butyl, 2-ethylhexyl, cyclohexyl, etc.), 2-hydroxylethyl acrylate, 2-hydroxylethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate and other hydroxy group-containing monomers, acrylamide, methacrylicamide, N-methylmethacrylicamide, etc. , N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylicamide, N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate and other amino group-containing monomers, glycidyl acrylate, glycidyl methacrylate and other glycidyl group-containing monomers , Acrylic acid, methacrylic acid and a monomer containing a carboxyl group of a carboxyl group thereof (sodium salt, potassium salt, ammonium salt, etc.) or a salt thereof and the like can be used. Further, as the urethane component in the present invention, a resin obtained by reacting a polyhydroxy compound and a polyisocyanate compound by a known polymerization method of urethane resin such as emulsion polymerization or suspension polymerization can be used. Examples of the polyhydroxy compound constituting the urethane component include polyethylene glycol, polypropylene glycol, polyethylene / polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-pentanediol, diethylene glycol, triethylene glycol, and poly. Caprolactone, polyhexamethylene adipate, polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate, trimethylolpropane, trimethylolethane, pentaerythritol, polycarbonate diol, glycerin and the like can be used.

As the cross-linking agent constituting the easy-adhesion layer in the present invention, it is preferable to copolymerize a cross-linking functional group, for example, a melamine-based cross-linking agent, an isocyanate-based cross-linking agent, an aziridine-based cross-linking agent, an epoxy-based cross-linking agent, and methylolation. Alternatively, an alkylolized urea-based cross-linking agent, acrylamide-based cross-linking agent, polyamide-based cross-linking agent, oxazoline-based cross-linking agent, carbodiimide-based cross-linking agent, various silane coupling agents, various titanate-based coupling agents and the like can be used. Further, from the viewpoint of moisture resistance and heat adhesion to the hard coat layer and the silicone-based adhesive layer, it is preferable to use two or more kinds of cross-linking agents. Specifically, at least one kind of cross-linking agent is an oxazoline-based cross-linking agent or carbodiimide. It is preferable to use a system cross-linking agent.

Further, since it is easy to be charged if it is only the component of the easy-adhesion layer, as a result, foreign matter may be mixed in during processing due to static electricity, which may cause a problem of appearance defects. Therefore, it is preferable that the component of the easy-adhesion layer contains a conductive polymer from the viewpoint of antistatic. As the conductive polymer, polypyrrole, polyaniline, polyacetylene, polythiophene vinylene, polyphenylene sulfide, poly-p-phenylene, polyheterocycle vinylene, particularly preferably (3,4-ethylenedioxythiophene) (PEDOT). is there.

By providing a hard coat layer on the surface of the thermoplastic resin film of the present invention, it is possible to prevent the thermoplastic resin film from being damaged and to impart scratch resistance. However, it is not always necessary to provide the hard coat layer for applications that do not require the hard coat layer from the viewpoint of cost.

As the hard coat layer, for example, an acrylic resin, a urethane resin, a melamine resin, an organic silicate resin, a silicone resin, or the like can be used. Among them, silicone-based resin and acrylic-based resin are preferable, and acrylic-based resin is more preferable, and active ray-curable acrylic-based resin is most preferable, from the viewpoint of hardness, durability and productivity.

The composition of the hard coat layer can be blended with various additives as necessary without impairing the effects of the present invention. For example, antioxidants, light stabilizers, stabilizers such as ultraviolet absorbers, surfactants, leveling agents, antistatic agents and the like can be used. The thickness of the hard coat layer in the present invention is determined according to the intended use, but is usually preferably 0.1 μm or more and 30 μm or less, and more preferably 1 μm or more and 15 μm or less. When the thickness of the hard coat layer is less than 0.1 μm, even if the composition of the hard coat layer is sufficiently cured, the surface hardness becomes low because the film thickness is too thin, and it may be easily scratched. When the thickness of the hard coat layer exceeds 30 μm, the cured film may be easily cracked due to stress such as bending.

In the thermoplastic resin film of the present invention, in addition to the easy-adhesion layer, the hard coat layer and the antistatic layer, an abrasion resistant layer, an antireflection layer, a color correction layer, an ultraviolet absorbing layer, a printing layer, a metal layer and a transparent conductive layer. , A functional layer such as a gas barrier layer, a hologram layer, a peeling layer, an adhesive layer, an embossing layer, and an adhesive layer may be formed.

Next, an example of a preferable method for producing the thermoplastic resin film of the present invention will be described below, but the present invention is not limited thereto.

First, two types of resin A and resin B are prepared in the form of pellets. The pellets are dried in hot air or under vacuum, if necessary, and then supplied to two extruders, respectively. In each extruder, the resin heated and melted above the melting point is equalized by a gear pump or the like to equalize the extrusion amount of the resin and remove foreign substances and modified resin through a filter or the like. The resin A and the resin B, which are sent out from different flow paths by using two extruders, are sent to the multilayer laminating device, respectively. As the multi-layer stacking device, it is desirable to use a feed block containing at least two or more members having a large number of fine slits separately. When such a feed block is used, the apparatus does not become extremely large, so that there are few foreign substances due to thermal deterioration, and even when the number of layers is extremely large, the layers can be laminated with high accuracy. In addition, the stacking accuracy in the width direction is also significantly improved as compared with the conventional technique. It is also possible to form an arbitrary layer thickness configuration.

When a two-stage or more inclined structure is adopted, the change from a thin layer to a thick layer or the change from a thick layer to a thin layer becomes very steep. In the present invention, a feed block containing at least two or more members having a large number of fine slits is used. However, at the place where the resins sent from the separate feed blocks merge, the layer thickness distribution changes immediately after the merge, which is a major factor in causing the color tone in the width direction to vary. Therefore, it is necessary to adjust the flow rate so that the stacking ratio is 0.7 to 1.3 so that the flow rates of the resin A and the resin B do not change significantly at the portion corresponding to the layer having a thickness of 1 μm or less in the laminated film. Is. Further, the resin A has a low viscosity and the resin B has a high viscosity so that the resin B, which has a higher viscosity than the resin A in the molten state, is not distorted due to the difference in shear stress in the layer. Therefore, the desired layer thickness distribution can be obtained. Furthermore, since the resin speed in the vicinity of the pipe decreases due to the influence of the wall surface of the pipe in the path from the feed block to the base, the film laminating accuracy further deteriorates due to the difference in flow velocity between the vicinity of the wall surface of the pipe and the center of the pipe. Therefore, by substituting the same polymer for a certain distance between the outermost layer of the film and the resin confluence of the separate feed blocks, the thermoplastic resin has a narrow wavelength band for the rise and fall of reflection without breaking the stacking ratio. You can get the film. At this time, when the outermost thick film layers on both sides of the laminated film are resin A, the layer made of resin A corresponds to the surface thick film layer (the outermost layers on both sides). Further, the resin used as the thick film layer of the inner layer is preferably a highly crystalline resin in order to improve the imprint resistance. If the thick film layer of the inner layer is less than 2 μm, the suppression of the change in the layer thickness distribution at the confluence is not sufficient, and it is necessary that the thickness is 2 μm or more. To adjust the thickness of the thick film layer, it is preferable to adjust each flow rate corresponding to the thickness of the corresponding layer in the slit gap, and at this time, the gap accuracy of each slit gap is preferably ± 10 μm or less. By using such a special feed block, it is possible to obtain a thermoplastic resin film having high accuracy and forming an inclined structure of two or more steps.

The molten laminate thus formed into a desired layer structure is then molded into a desired shape by a die and then discharged. Then, the multi-layered sheet discharged from the die is extruded onto a rotary cooling body such as a casting drum and cooled and solidified to obtain a casting film (non-stretched film). At this time, it is preferable to use a wire-shaped, tape-shaped, wire-shaped, or knife-shaped electrode to bring it into close contact with a rotating cooling body such as a casting drum by electrostatic force to quench and solidify it. Further, a method of blowing air from a slit-shaped, spot-shaped, or planar device to bring it into close contact with a rotary cooling body such as a casting drum for quenching and solidification, or a method of bringing it into close contact with a rotating cooling body with a nip roll and quenching and solidifying is also preferable.

The casting film (non-stretched film) thus obtained is preferably biaxially stretched as needed. Biaxial stretching means stretching in the longitudinal direction and the width direction. The stretching may be sequentially biaxially stretched or simultaneously bidirectionally stretched. Further, it may be further re-stretched in the longitudinal direction and / or the width direction. In particular, in the present invention, it is preferable to use simultaneous biaxial stretching from the viewpoint of suppressing the in-plane orientation difference and suppressing surface scratches.

First, the case of sequential biaxial stretching will be described. Here, the stretching in the longitudinal direction means stretching for giving molecular orientation to the film in the longitudinal direction, and is usually performed by the difference in peripheral speed of the rolls, and this stretching may be performed in one step, or may be performed in a plurality of steps. It may be performed in multiple steps using a roll pair of books. The stretching ratio varies depending on the type of resin, but is usually preferably 2 to 15 times, and when polyethylene terephthalate is used for the thermoplastic resin film, 2 to 7 times is particularly preferably used. The stretching temperature is preferably from the glass transition temperature to the glass transition temperature of the resin constituting the thermoplastic resin film + 100 ° C.

When an easy-adhesion layer is provided on the thermoplastic resin film of the present invention, a method of coating and laminating a coating agent is preferable. As a method of coating the coating agent, a method of coating in a process different from the polyester film manufacturing process of the present invention, a so-called offline coating method, and a method of coating during the polyester film manufacturing process of the present invention make it easy to adhere. There is a so-called in-line coating method in which layers are laminated at once. It is preferable to adopt the in-line coating method from the viewpoint of cost and uniform coating thickness, and the solvent of the coating liquid used in that case is preferably water-based from the viewpoint of environmental pollution and explosion resistance, and water is used. It is the most preferable embodiment to use.

When laminating the easy-adhesive layer by in-line coating, the coating agent constituting the easy-adhesive layer is continuously applied to the uniaxially stretched polyester film. As a coating method using water as a solvent (water-based coating agent), for example, a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method and the like can be used.

Before applying the water-based coating agent, it is preferable to apply a corona discharge treatment or the like to the surface of the polyester film. This is because the adhesiveness between the polyester film and the coating agent is improved, and the coating property is also improved.

The easy-adhesion layer may be a cross-linking agent, an antioxidant, a heat-resistant stabilizer, a weather-resistant stabilizer, an ultraviolet absorber, an organic slipper, a pigment, a dye, an organic or inorganic material, as long as the effect of the invention is not impaired. Particles, fillers, surfactants and the like may be blended.

Subsequent stretching in the width direction refers to stretching for giving molecular orientation in the width direction of the film, and is usually carried by using a tenter while gripping both ends of the film with clips to apply heat to the film. After preheating, it is stretched in the width direction. The water-based coating applied immediately before the tenter is dried during this preheating. The stretching ratio varies depending on the type of resin, but is usually preferably 2 to 15 times, and particularly preferably 2 to 7 times when polyethylene terephthalate is used as any of the resins constituting the polyester film in the present invention. .. The stretching temperature is preferably from the glass transition temperature to the glass transition temperature + 120 ° C. of the resin constituting the polyester film in the present invention. The biaxially stretched polyester film is preferably heat-treated in a tenter to have a stretching temperature or higher and a melting point or lower in order to impart flatness and dimensional stability. After being heat-treated in this manner, it is uniformly slowly cooled, cooled to room temperature, and wound up by a winder. Further, if necessary, a relaxation treatment or the like may be used in combination from the heat treatment to the slow cooling.

Next, the case of simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the coating film constituting the easy-adhesion layer is continuously applied to the obtained cast film. As a coating method using water as a solvent (water-based coating agent), for example, a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method and the like can be used.

Before applying the water-based coating material, it is preferable to apply a corona discharge treatment or the like to the surface of the thermoplastic resin film of the present invention. This is because the adhesiveness between the polyester film and the coating agent is improved, and the coating property is also improved. Next, the cast film (non-stretched film) coated with the coating material is guided to the simultaneous biaxial tenter, transported while gripping both ends of the film with clips, and stretched simultaneously and / or stepwise in the longitudinal and width directions. To do. Simultaneous biaxial stretching machines include pantograph type, screw type, drive motor type, and linear motor type. The drive motor type or the drive motor type that can change the stretching ratio arbitrarily and can perform relaxation processing at any place. The linear motor method is preferable. The stretching ratio varies depending on the type of resin, but usually, the area ratio is preferably 6 to 50 times, and the area ratio is particularly preferably 8 to 30 times. In particular, in the case of simultaneous biaxial stretching, it is preferable that the stretching ratios in the longitudinal direction and the stretching direction are the same and the stretching speeds are substantially the same in order to suppress the in-plane orientation difference. The stretching temperature is preferably from the glass transition temperature of the resin constituting the polyester film to the glass transition temperature + 120 ° C. In order to impart flatness and dimensional stability to the biaxially stretched film, it is preferable that the biaxially stretched film is subsequently subjected to heat treatment in the tenter to be equal to or higher than the stretching temperature and lower than the melting point. At the time of this heat treatment, in order to suppress the distribution of the main orientation axis in the width direction, it is preferable to perform the relaxation treatment in the longitudinal direction instantly immediately before and / or immediately after entering the heat treatment zone. After being heat-treated in this manner, it is uniformly slowly cooled, cooled to room temperature, and wound up by a winder. Further, if necessary, relaxation treatment may be performed in the longitudinal direction and / or the width direction during heat treatment and slow cooling. Immediately before and / or immediately after entering the heat treatment zone, it is preferable to perform relaxation treatment in the longitudinal direction.

The thermoplastic resin film of the present invention thus obtained highly reflects visible light, has a large coloration when viewed from the front, and has a remarkable change in saturation with a slight change in angle. Therefore, an anti-counterfeit sheet and an IC card are added. It can be suitably used for decoration, decoration of home appliances, decoration film used for arts and crafts, and the like. Further, since the thermoplastic resin film of the present invention has achieved high visible light reflectivity and a change in saturation with a slight angle change without using a metal, the thermoplastic tax resin film of the present invention was used. Since the anti-counterfeit sheet is excellent in recyclability and electromagnetic wave transmission, it can be suitably used for various IC cards and securities.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. The characteristics were measured by the following methods.

(1) Layer structure and layer thickness of the film For a sample whose cross section was cut out using a microtome, a transmission electron microscope (H-7100FA type manufactured by Hitachi, Ltd.) was used, and the cross section of the film was 40 at an acceleration voltage of 75 kV. The observation was performed at a magnification of 000 times, and the cross-sectional portion was photographed to measure the layer composition and layer thickness. Further, the total thickness of each layer was taken as the total thickness of the laminated film. The sample was stained with _{RuO 4} in order to obtain high contrast.

A specific method for obtaining the layer structure and layer thickness of the film will be described. Approximately 40,000 times TEM photographs were captured using a CanonScanD123U (manufactured by Canon Inc.) with an image size of 729 dpi. The image was saved in JPEG format, and then the JPEG file was opened and image analysis was performed using image processing software (distributor Planetron Co., Ltd., Imagec-Pro Plus ver.4). In the image analysis process, in the vertical sick profile mode, the relationship with the average brightness in the region sandwiched between the two lines in the thickness direction and the width direction was read as numerical data. Using spreadsheet software (Excel2010), the position (nm) and brightness data were collected in sampling step 1 (thinning out 1), and then numerically processed by a 5-point moving average. Furthermore, the obtained data whose brightness changes periodically is differentiated, the maximum value and the minimum value of the differential curve are read by the VBA (Visual Basic for Applications) program, and the adjacent intervals between these are one layer. Calculated as the layer thickness. This operation was performed for each photograph, and the layer thickness of all the layers was calculated. Of the obtained layer thickness, the thin film layer was a layer having a thickness of less than 1 μm. A group in which the difference in thickness between adjacent layers between the A layer and the B layer is continuously monotonically increasing or monotonically decreasing within a range of 50 nm or less is defined as an inclined structure. The inclined structure has a positive or negative inclination such that the square of R is 0.90 or more when the relationship between the layer number and the layer thickness of each of the A layer and the B layer is approximated to the least squares. The two-stage inclined structure and the configuration shown in FIG. 2 are referred to as a three-stage inclined structure.

(2) 400-750 nm average reflectance A 5 cm square sample was cut out from the thermoplastic resin film. Next, the relative reflectance at an incident angle of Φ = 12 was measured using a spectrophotometer (U-4100 Spectrophotometer manufactured by Hitachi, Ltd.). The inner wall of the attached integrating sphere is barium sulfate, and the standard plate is aluminum oxide. The measurement wavelength was 250 nm to 1200 nm, the slit was 2 nm (visible) / automatic control (infrared), the gain was set to 2, and the measurement was performed at a scanning speed of 600 nm / min. The back surface of the sample was blackened with oil-based ink. Next, the average reflectance in the wavelength band of 400 to 750 nm was calculated. The average reflectance is calculated by calculating the area surrounded by the reflection curve and the wavelength band based on the Simpson method formula using the absolute reflectance data for each wavelength of 1 nm, and dividing by 350 nm, which is the width of the wavelength band. Therefore, the average reflectance was obtained. A detailed explanation of the Simpson's rule is given in "Numerical Calculation Method for Computers I" (Baifukan) (1965) by Jiro Yamauchi et al.

The absolute reflectance at an incident angle of Φ = 30 ° was measured under the same conditions as when the incident angle was Φ = 12 ° using an angle-variable absolute reflectance accessory, and the average reflectance was calculated.

(3) Low wavelength side λ _80- λ ₂₀ , high wavelength side λ _20- λ ₈₀
A 5 cm square sample was cut out from the thermoplastic resin film. _{R 80} and R ₂₀ defined by the following formulas were obtained from the reflectance in the wavelength band 400-750 nm measured by the method (2).
Lowest wavelength band of low wavelength side lambda ₈₀ wavelengths exceeding the reflectivity of R _80, a wavelength close to the lower wavelength side lambda ₈₀ most lambda ₈₀ exceeding the reflectance R ₂₀ in the low wavelength side and the low-wavelength-side lambda ₂₀ , the low-wavelength-side lambda ₈₀ - and the wavelength band of the low-wavelength-side lambda ₂₀ and the low-wavelength-side λ ₈₀ -λ _20.
High wavelength lambda ₈₀ wavelength exceeding reflectance R ₈₀ at the highest wavelength _band, the wavelength closest to lambda ₈₀ that exceeds the reflectance R ₂₀ from the high wavelength side lambda ₈₀ with high wavelength side and high wavelength side lambda ₂₀ , high wavelength side lambda ₂₀ - and the wavelength band of the high wavelength side lambda ₈₀ and the high wavelength side λ ₂₀ -λ _80.
Equation (iii) R ₈₀ = {(maximum reflectance-minimum reflectance) x 0.8} + minimum reflectance (%)
Equation (iv) R ₂₀ = {(maximum reflectance-minimum reflectance) x 0.2} + minimum reflectance (%)
(4) Color tone (a ^* [12 °], b ^* [12 °]), (a ^* [30 °], b ^* [30 °])
From the spectral reflectance data obtained in (2), a spectral reflection curve obtained by averaging these from the P wave and the S wave of the spectral reflection curves at incident angles of 12 ° and 30 ° was obtained. Next, from the average spectral reflection curve of each angle, using the calculation formula specified in JISZ8781, a ^* [12 °], b ^* [12 °], a ^* [30 °], b ^* [ 30 °] was calculated.

(5) Saturation C ^* [12 °]
^{From the numerical values of (a *} [12 °], b ^* [12 °]) obtained in (4), the ^{saturation C *} [12 °] was obtained from the following equation.
Equation (ii) C ^* [12 °] = √ (a ^* [12 °] ² + b ^* [12 °] ² )
(6) ΔC ^* (angle-dependent saturation difference) (incident angle 12 ° / 30 ° saturation difference)
^{From the numerical values of (a *} [12 °], b ^* [12 °]), (a ^* [30 °], b ^* [30 °]) obtained in (4), ^{ΔC *} (angle-dependent) from the following equation Saturation difference) (incident angle 12 ° / 30 ° saturation difference) was calculated.
Equation (i) √ {(a ^* [12 °] -a ^* [30 °]) ² + (b ^* [12 °] -b ^* [30 °]) ² }
(7) The haze was performed at 23 ° C. and a relative humidity of 65% using a turbidity meter NDH-5000 manufactured by Nippon Denshoku Kogyo Co., Ltd. The average value measured three times was used as the haze value.

(8) Colorability when viewed from the front (5) Saturation C ^{* Based on} the measurement results of [12 °], evaluation was performed according to the following criteria.
⊚: C ^* [12 °] = 40 or more ○: C ^* [12 °] = 30 or more and less than 40 ×: C ^* [12 °] = less than 30.

(9) Changeability of angle coloring (6) Based ^{on the measurement results of ΔC *} (angle-dependent saturation difference), evaluation was performed according to the following criteria.
⊚: ΔC ^* (angle-dependent saturation difference) = 40 or more ○: ΔC ^* (angle-dependent saturation difference) = 30 or more and less than 40 Δ: ΔC ^* (angle-dependent saturation difference) = 25 or more and less than 30 ×: ΔC ^* (Angle-dependent saturation difference) = less than 25.

(10) High reflectance (2) Based on the measurement results of the 400-750 nm average reflectance, the evaluation was made according to the following criteria.
⊚: 400-750 nm average reflectance = 50% or more ◯: 400-750 nm average reflectance = 40% or more and less than 50% Δ: 400-750 nm average reflectance = 30% or more and less than 40% ×: 400-750 nm average reflectance = Less than 30%.

(11) Adhesiveness between layers In accordance with JIS K5600-5-6-1999, a cross-cut spacing spacer (manufactured by Cortec Co., Ltd .: model number CROSS CUT GUIDE 1.0) and a cutter knife are used, and the vertical direction 6 is applied to the evaluation specimen. Make 6 cuts in the horizontal direction at 1 mm intervals (this operation creates a grid of 5 x 5 = 25 squares). A transparent pressure-sensitive adhesive tape (manufactured by Nitto Denko Corporation: model number 31B) was crimped onto the produced grid, and the crimped tape was peeled off in a direction of about 60 ° to determine the number of peeled grids. The measurement was carried out at N = 5, and the average value was evaluated according to the following criteria.
◯: No peeling in all 25 squares (the number of peeled squares is 0 squares or more and less than 1 square)
Δ: 1 or more and less than 2 grids in 25 squares are peeled off ×: 2 or more squares in 25 squares are peeled off.

(material)
(Resin A-1)
To a mixture of 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, 0.09 part by weight of magnesium acetate and 0.03 part by weight of antimony trioxide were added to the amount of dimethyl terephthalate, and the temperature was raised by heating by a conventional method. Then, the transesterification reaction is carried out. Next, 0.020 parts by weight of an 85% phosphoric acid aqueous solution is added to the transesterification reaction product with respect to the amount of dimethyl terephthalate, and then the mixture is transferred to a polycondensation reaction tank. Further, the reaction system is gradually depressurized while heating and raising the temperature, and a polycondensation reaction is carried out at 290 ° C. by a conventional method under a reduced pressure of 1 mmHg to obtain polyethylene terephthalate having an intrinsic viscosity (IV) of 0.61 (hereinafter referred to as PET). There is) got.

(Resin A-2)
Polyethylene naphthalate having an intrinsic viscosity (IV) of 0.67 was polymerized in the same manner as resin A-1, except that a mixture of 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylic acid and 60 parts by weight of ethylene glycol was used. , PEN) was obtained.

(Resin A-3)
The polycondensation reaction time was adjusted during resin A-1 polymerization to obtain polyethylene terephthalate having an intrinsic viscosity (IV) of 0.66 (hereinafter, may be referred to as PET).

(Resin B-1)
A copolymerized polyethylene terephthalate in which 21 mol% of spiroglycol (SPG) having an intrinsic viscosity (IV) of 0.60 and 24 mol% of cyclohexanedicarboxylic acid (CHDC) are copolymerized and resin A-3 is mixed at a ratio of 4: 1.
(Resin B-2)
A copolymerized polyethylene terephthalate obtained by mixing 30 mol% of cyclohexanedimethanol (CHDM) having an intrinsic viscosity (IV) of 0.75 and a resin A-3 at a ratio of 4: 1.
(Resin B-3)
A copolymerized polyethylene terephthalate obtained by mixing 30 mol% of cyclohexanedimethanol (CHDM) having an intrinsic viscosity (IV) of 0.75 and a resin A-3 in a ratio of 3: 2.

(Resin B-4)
A copolymerized polyethylene terephthalate in which 21 mol% of spiroglycol (SPG) having an intrinsic viscosity (IV) of 0.55 and 24 mol% of cyclohexanedicarboxylic acid (CHDC) are copolymerized and resin A-3 is mixed at a ratio of 4: 1.

(Resin B-5)
A copolymerized polyethylene terephthalate obtained by mixing 30 mol% of cyclohexanedimethanol (CHDM) having an intrinsic viscosity (IV) of 0.70 and a resin A-3 at a ratio of 4: 1.

(Resin B-6)
A copolymerized polyethylene terephthalate obtained by mixing 30 mol% of cyclohexanedimethanol (CHDM) having an intrinsic viscosity (IV) of 0.75 and a resin A-3 in a ratio of 2: 3.

(Composition of Easy Adhesive Layer-I)
-Acrylic / urethane copolymer resin (a) aqueous dispersion: manufactured by Yamanan Synthetic Chemical Co., Ltd., Sannaron WG658 (solid content concentration 30% by weight)
-Aqueous dispersion of isocyanate compound (b): Elastron E-37 (solid content concentration 28% by weight) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.
-Aqueous dispersion of epoxy compound (c): manufactured by DIC Corporation, CR-5L (solid content concentration 100% by weight)
An aqueous dispersion (solid content concentration 1.3% by weight) of the composition (d) composed of a compound having a polythiophene structure and a compound having an anionic structure.
-Aqueous dispersion of oxazoline compound (e): Epocross WS-500 (solid content concentration 40% by weight) manufactured by Nippon Shokubai Co., Ltd.
-Aqueous dispersion of carbodiimide compound (f): Carbodilite V-04 (solid content concentration 40%) manufactured by Nisshinbo Holdings Inc.
-Silica particles (g): Spherica slurry 140 (solid content concentration 40%) manufactured by JGC Catalysts and Chemicals Co., Ltd.
-Acetylenediol-based surfactant (h): manufactured by Nissin Chemical Co., Ltd., Orphine EXP4051 (solid content concentration 50%)
-Aqueous solvent (i): pure water The above (a) to (h) in terms of solid content weight ratio (a) / (b) / (c) / (d) / (e) / (f) / ( Mix so that g) / (h) = 100/100/75/25/60/60/10/15, and add (i) so that the solid content concentration of the aqueous coating is 3% by weight. The mixture was mixed and the concentration was adjusted.

(Example 1)
Resin A-1 and resin B-1 are melted at 280 ° C. and resin B-1 at 270 ° C. using separate twin-screw extruders with vents, and then passed through a gear pump and a filter. The members having 274 slits were joined by a 549-layer feed block having one separately. The outermost layers on both sides of the thick film layer are resin A-1, resin A-1 and resin B-1 are alternately laminated, and the layers are composed of adjacent resin A-1 and resin B-1. The layer thickness of the layers was made to be almost the same. Next, the film was guided to a T-die and molded into a sheet, and then brought into close contact with a casting drum maintained at a surface temperature of 25 ° C. by electrostatic application and rapidly cooled and solidified to obtain a cast film.

The obtained cast film was heated in a roll group set at 75 ° C., then stretched 3.3 times in the vertical direction while being rapidly heated from both sides of the film by a radiation heater for a stretched section length of 100 mm, and then cooled once. A uniaxially stretched film was obtained. Next, both sides of the uniaxially stretched film were subjected to a corona discharge treatment in air to set the coating tension of the film to 55 mN / m, and the composition-I of the easy-adhesion layer was applied to both sides of the film with a # 4 metabar.

The obtained uniaxially stretched film was guided to a tenter, preheated with hot air at 100 ° C., and then stretched 3.5 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 240 ° C., then subjected to a 7% relaxation treatment in the width direction at the same temperature, then cooled to room temperature and wound with a winder. A shaft stretched film was obtained. The total thickness of the obtained biaxially stretched laminated film was 70 μm. The layer design of this laminated film is as shown in FIG. 1, and the layer thickness of each layer was controlled by adjusting the slit gap. The cross section of the laminated film in the thickness direction was observed by TEM, and the layer thickness distribution was obtained by image processing. The layer thicknesses of the outermost layers, layer No. 1 and layer number 549, were both 6 μm, and the layer thickness of layer number 275 composed of the resin A-1 was 4 μm. Table 1 shows the characteristics and evaluation results of this thermoplastic resin film.

(Example 2)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the overall thickness of the film was changed from 70 μm to 80 μm. The results are shown in Table 1.

(Example 3)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the overall thickness of the film was changed from 70 μm to 60 μm. The results are shown in Table 1.

(Example 4)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the resin B-1 was changed to the resin B-2. The results are shown in Table 1.

(Example 5)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the resin B-1 was changed to the resin B-3. The results are shown in Table 1.

(Example 6)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the resin A-1 was changed to the resin A-2. The results are shown in Table 1.

(Example 7)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the slit shape of the feed block was changed to adjust the thickness of the film layer design so as to be shown in FIG. 2 and the total thickness of the laminated film was set to 76 μm. The layer thicknesses of the outermost layers, layer number 1 and layer number 549, were both 6 μm, and the layer thicknesses of layer number 183 and layer number 366 composed of the resin A-1 were 4 μm. Table 1 shows the characteristics and evaluation results of this thermoplastic resin film.

(Example 8)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the slit shape of the feed block was changed to adjust the thickness of the film layer design so as to be shown in FIG. 3 and the total thickness of the laminated film was 45 μm. The layer thicknesses of the outermost layers, layer No. 1 and layer number 349, were both 6 μm, and the layer thickness of layer number 175 composed of the resin A-1 was 4 μm. Table 1 shows the characteristics and evaluation results of this thermoplastic resin film.

(Example 9)
A thermoplastic resin film was obtained in the same manner as in Example 8 except that the overall thickness of the film was changed from 45 μm to 35 μm. The results are shown in Table 1.

(Example 10)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the slit shape of the feed block was changed to adjust the thickness of the film layer design so as to be shown in FIG. 4 and the total thickness of the laminated film was 34 μm. The layer thicknesses of the outermost layers, layer No. 1 and layer number 249, were both 6 μm, and the layer thickness of layer number 125 composed of the resin A-1 was 4 μm. Table 1 shows the characteristics and evaluation results of this thermoplastic resin film.

(Comparative Example 1)
Same as Example 1 except that resin A-1 was changed to resin A-3, resin B-1 was changed to resin B-4, and resin B-4 was changed to a molten state at 280 ° C. using a twin-screw extruder with a vent. A thermoplastic resin film was obtained. The results are shown in Table 1.

(Comparative Example 2)
A thermoplastic resin film was obtained in the same manner as in Comparative Example 1 except that the overall thickness of the film was changed from 70 μm to 80 μm. The results are shown in Table 1.

(Comparative Example 3)
A thermoplastic resin film was obtained in the same manner as in Comparative Example 1 except that the overall thickness of the film was changed from 70 μm to 60 μm. The results are shown in Table 1.

(Comparative Example 4)
A thermoplastic resin film was obtained in the same manner as in Comparative Example 1 except that the resin B-1 was changed to the resin B-5. The results are shown in Table 1.

(Comparative Example 5)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the resin B-1 was changed to the resin B-6. The results are shown in Table 1.

(Comparative Example 6)
A thermoplastic resin film was obtained in the same manner as in Example 1 except that the slit shape of the feed block was changed to adjust the thickness of the film layer design so as to be shown in FIG. 5 and the total thickness of the laminated film was 24 μm. The layer thicknesses of the outermost layers, layer No. 1 and layer number 149, were both 10 μm, and the layer thickness of layer number 75 composed of the resin A-1 was 4 μm. Table 1 shows the characteristics and evaluation results of this thermoplastic resin film.

The thermoplastic resin film of the present invention highly reflects visible light, has a large coloration when viewed from the front, and has a remarkable change in saturation with a slight change in angle. Therefore, by utilizing its characteristics, it can be suitably used for anti-counterfeit sheets, IC card decorations, decorations for home appliances, decoration films used for arts and crafts, and the like.

1: Layer number 2: Layer thickness 3: Thick film layer 4: Layer thickness distribution of layer A 5: Layer thickness distribution of layer B 6: Member plate 7: Resin introduction plate 8: Slit plate 8a: Slit 8b: Slit 9: Resin introduction plate 10: Slit plate 11: Resin introduction plate 12: Slit plate 13: Resin introduction plate 14: Slit plate 15: Resin introduction plate 16: Member plate 17: Feed block 18: Introduction port 19: Liquid reservoir 20: Each Ridge line at the top of the slit 21: Upper end of the ridgeline at the top of each slit 22: Lower end of the ridgeline at the top of each slit 23: Resin introduced into the slit 24: Resin outlet

Claims (5)

The average reflectance in the wavelength band 400-750 nm measured at an incident angle of 12 ° is 30% or more, and the spectral reflectance measured at an incident angle of 12 ° and 30 ° is a color tone calculated using the formula specified in JISZ8781. The values (a ^* [12 °], b ^* [12 °]), (a ^* [30 °], b ^* [30 °]) satisfy the following equation (i).
It has a layer containing a thermoplastic resin A as a main component (A layer) and a layer containing a thermoplastic resin B as a main component (B layer), and the A layer and the B layer are adjacent to each other. The total number of layers and the B layer is 200 or more,
The thermoplastic resin A is a crystalline thermoplastic resin, and the thermoplastic resin B is an amorphous thermoplastic resin.
The crystalline thermoplastic resin is crystalline polyethylene terephthalate or crystalline polyethylene naphthalate, and the amorphous thermoplastic resin is spiroglycol copolymerized polyethylene terephthalate and / or cyclohexanedimethanol copolymerized polyethylene terephthalate. A thermoplastic resin film characterized by.
Equation (i) √ {(a ^* [12 °] -a ^* [30 °]) ² + (b ^* [12 °] -b ^* [30 °]) ² } ≧ 25 The thermoplastic resin film according to claim 1, wherein the color tone values (a ^* [12 °], b ^* [12 °]) satisfy the following formula (ii).
Equation (ii) √ (a ^* [12 °] ² + b ^* [12 °] ² ) ≧ 30 The thermoplastic resin film according to claim 1 or 2, wherein delamination does not occur in an adhesion test by a cross-cut method according to JIS K5600. The thermoplastic resin film according to any one of claims 1 to 3, which is used for an anti-counterfeit sheet. An anti-counterfeit sheet using the thermoplastic resin film according to any one of claims 1 to 4.

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