JP2007137058A - Method of manufacturing embossed sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing embossed sheet capable of manufacturing embossed sheets having various kinds of stereoscopic patterns, from one original disk provided with stereoscopic patterns for transferring. <P>SOLUTION: When a load is applied to a prism sheet 11a provided with a first stereoscopic pattern in the ridgeline direction shown by arrow P, the prism sheet 11a is elongated along an axis parallel to the ridgeline direction, and shrunk along an axis parallel to the cross-sectional direction. Thereby, a prism sheet 11b provided with a second stereoscopic pattern having a figure similar to the first stereoscopic pattern can be obtained, from the prism sheet 11a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an embossed sheet provided with an optical function by forming a desired three-dimensional pattern on one main surface.

  Today, films or sheets that utilize the optical properties of synthetic resins are deeply involved in industrial and daily life. However, most of them have a smooth surface, and the light transmittance is adjusted simply by competing for the transparency of the synthetic resin, or by making the surface matt or adding additives. there were.

  In recent years, embossed sheets having a special surface structure and utilizing mainly actions such as reflection, refraction, and scattering, and embossed sheets that combine these have been in the limelight. Such an embossed sheet is widely used as a light transmissive film such as a prism sheet, an antiglare sheet or a diffusion sheet, which is a constituent unit of a liquid crystal display device used in a notebook PC (Personal Computer), a liquid crystal television, and the like. ing.

  Conventionally, as a method of forming a three-dimensional pattern on a plastic surface, there are a method of press molding using a master having a desired three-dimensional pattern, or a method of injection molding. For example, in Patent Document 1 below, as an example of press molding, a sheet is hot-pressed using one mold provided with a three-dimensional pattern on one side and another mold, and a desired three-dimensional pattern is formed. A method for producing an embossed sheet provided is described.

Japanese Patent No. 3607759

  However, the production of the master used to form the three-dimensional pattern of the embossed sheet requires a precise cutting process and takes a long time. Furthermore, the master itself requires high shape accuracy and is expensive.

  This invention is made | formed in view of the above-mentioned problem, and makes it a subject to provide the manufacturing method of the embossed sheet which can manufacture the embossed sheet which has a various three-dimensional pattern from one master provided with the three-dimensional pattern for transcription | transfer.

  In solving the above problems, an embossed sheet manufacturing method according to the present invention deforms an embossed sheet provided with a first three-dimensional pattern on one principal surface in at least one axial direction, and the second on the one principal surface. Forming a three-dimensional pattern.

  The embossed sheet provided with various three-dimensional patterns can be manufactured from one master by deforming the embossed sheet provided with the first three-dimensional pattern in at least one axial direction to form the second three-dimensional pattern. it can.

  The embossed sheet can form a second three-dimensional pattern similar to the first three-dimensional pattern by stretching along an axis parallel to the ridge line direction of the first three-dimensional pattern. Moreover, the embossed sheet can form a second three-dimensional pattern obtained by flattening the first three-dimensional pattern by stretching along an axis parallel to the cross-sectional direction of the first three-dimensional pattern.

  In the present invention, the similar shape means that the cross sections of the first and second three-dimensional patterns are uniformly enlarged or reduced and overlapped. Here, the cross sections of the first and second three-dimensional patterns are cross sections when the first and second three-dimensional patterns are cut along a plane perpendicular to the extending direction.

  In addition, the three-dimensional pattern is typically an isosceles triangle with various apex angles, a slightly inclined triangle with a cross section, a continuous shape such as a large or small triangle, a cross-sectional waveform with a sinusoidal shape, It is a lens array shape with a semicircular shape with many cross-sections, pyramid and hemispherical units.

There is a prism sheet as an embossed sheet provided with a continuous shape such as an isosceles triangle whose cross section has various apex angles, an unequal triangle with a slight inclination, and a large and small triangle.
There is a lenticular sheet as an embossed sheet provided with a sinusoidal cross section and a semi-circular shape with many cross sections.
As an embossed sheet provided with a lens array shape having pyramid or hemispherical units, there is a lens array sheet.

  Further, as the three-dimensional pattern, typically, a large number of peaks having a convex or convex cross section and a large number of valleys having a concave or concave cross section are arranged alternately and substantially in parallel. Say. In this case, there is only one slope, peak, and valley bottom formed by a convex or convex arc-shaped cross section and a concave or concave arc-shaped cross section formed alternately in parallel on one side. Or it may be comprised by several planes, may be formed from the curved surface, and may be formed from both the plane and the curved surface. The slopes of the flat and curved slopes are very important for the performance of collecting light in the front, but may be designed according to the desired performance. Further, the narrower the gap between the crests and crests and the crests and troughs formed in parallel, the better the surface uniformity, and preferably 150 μm or less.

  Furthermore, the sheet typically includes not only a sheet in a strict sense limited by the thickness but also a thin sheet usually called a film. The average thickness is typically preferably 50 μm or more, more preferably 100 μm to 350 μm.

  On the other hand, when the embossed sheet is stretched to form the second three-dimensional pattern, the refractive index can be made different between the stretching direction and the non-stretching direction in the surface of the embossed sheet. Specifically, the embossed sheet made of synthetic resin has the property that the refractive index increases or decreases in the stretching direction depending on the type of material, so the embossed sheet after stretching has an anisotropic refractive index in the plane. It will have sex. Thereby, the light transmission film which has in-plane anisotropy in an optical characteristic can be comprised by having a difference in a refractive index by the extending | stretching direction and a non-stretching direction.

  As described above, according to the present invention, an embossed sheet provided with various three-dimensional patterns can be manufactured from one master having a three-dimensional pattern for transfer.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, the manufacturing method of the prism sheet by one Embodiment of this invention is demonstrated. In this manufacturing method, a prism sheet provided with a first three-dimensional pattern is manufactured from a single master plate provided with a three-dimensional pattern for transfer, and the first three-dimensional pattern is deformed to produce various three-dimensional patterns. The prism sheet which has it is manufactured.

  FIG. 1 shows an example of a prism sheet manufactured by the prism sheet manufacturing method according to the present embodiment. The prism sheet 1 is used, for example, for improving the luminance of a backlight of a liquid crystal display (liquid crystal display device) and improving alignment characteristics. As shown in FIG. 1, a three-dimensional pattern in which a plurality of prism rows each having a cross section of a right isosceles triangle is provided on one main surface of the prism sheet 1.

  As a material of the prism sheet 1, a light-transmitting thermoplastic resin that can be deformed at a predetermined temperature can be used. The predetermined temperature here is, for example, in the vicinity of the glass transition point (Tg) of the thermoplastic resin, more specifically, for example, in the range of Tg ± 40 ° C.

  For example, the material of the prism sheet 1 needs to have optical transparency in terms of use as a material for a planar light emitter light control sheet for optical applications, particularly for liquid crystal displays, for example, a function for controlling the light emission direction. Is required, a thermoplastic resin having a refractive index of 1.4 or more is preferable.

  More specifically, examples of the material of the prism sheet 1 include, for example, an aramid resin, a polycarbonate resin, an acrylic resin typified by polymethyl methacrylate resin, a polyester resin typified by polyethylene terephthalate, an amorphous copolyester resin, and polystyrene. Examples thereof include resins and polyvinyl chloride resins. In addition, aramid resin, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN) are preferable from the viewpoint of obtaining a second three-dimensional pattern similar in shape to the first three-dimensional pattern.

  Next, an example of a method for manufacturing a prism sheet according to the first embodiment of the present invention will be described. In the present embodiment, an example will be described in which a prism sheet provided with a second three-dimensional pattern similar to the first three-dimensional pattern is formed from a prism sheet provided with the first three-dimensional pattern.

  FIG. 2 is a schematic diagram for explaining a manufacturing process of the prism sheet provided with the first three-dimensional pattern. First, the prism sheet manufacturing apparatus used in the manufacturing process of the prism sheet provided with the first three-dimensional pattern will be described with reference to FIG. This prism sheet manufacturing apparatus includes pressure plates 34a and 34b, and a mirror plate 33 and a flat plate mold 32 are arranged between the pressure plates 34a and 34b. In addition, the mirror plate 33 and the flat plate metal are provided. A sheet 31 is disposed between the molds 32. Although not shown, the transmission film (prism sheet) manufacturing apparatus includes a press mechanism for pressing the pressure plates 34a and 34b and a vacuum for making the vicinity of the pressure plates 34a and 34b a vacuum atmosphere. And a chamber.

  The pressurizing plates 34 a and 34 b are for pressurizing the sheet 31 sandwiched between the mirror plate 33 and the flat plate mold 32. A heating mechanism such as a heater and a cooling mechanism such as a cooling pipe are provided inside the pressure plates 34a and 34b so that the pressure plates 34a and 34b can be heated and cooled. For example, water or oil is used as the refrigerant supplied to the cooling pipe.

  The mirror surface plate 33 is for forming a light incident side surface of the prism sheet 1 and has a thin plate shape, and both main surfaces thereof are flat. The flat plate mold 32 is for forming the light emitting side surface of the prism sheet 1 and has a thin plate shape. One main surface is provided with a fine shape for forming a prism (or prism lens) on one main surface of the sheet 31, and the other main surface is flat. The fine shape for forming the prism is formed, for example, by precision cutting with a diamond tool or laser processing. The flat plate mold 32 may be detachably provided on the pressing surface of the pressure plate 34b, and the pressure plate 34b and the flat plate mold 32 may be integrated. Alternatively, the mirror plate 33 may be detachably provided on the press surface of the pressure plate 34a, and the pressure plate 34b and the mirror plate 33 may be integrated.

  Next, the manufacturing process of the prism sheet provided with the first three-dimensional pattern will be described with reference to FIG. First, the sheet 31 is disposed between the flat plate mold 32 and the mirror plate 33, the flat plate mold 32 and the mirror plate 33 are sandwiched between the pressure plates 34a and 34b, and the vacuum chamber is evacuated. Thereafter, a predetermined force is applied to the pressure plate 34b in the direction indicated by the arrow to press the sheet 31. At this time, the pressure plates 34a and 34b are heated to a predetermined temperature. Thereby, the transfer of the fine shape provided on one main surface of the flat plate mold 32 can be made easier.

  Then, after pressurizing for a certain time, the pressure plates 34a and 34b are cooled by a cooling pipe (not shown) provided therein, and when the temperature of the pressure plates 34a and 34b reaches about room temperature, the pressure plate 34a. , 34b are opened. Through the above steps, a prism sheet provided with the first three-dimensional pattern can be obtained.

  Next, with reference to FIG. 3, the process of transforming from the first three-dimensional pattern to the second three-dimensional pattern will be described. FIG. 3 shows a prism sheet provided with a first three-dimensional pattern. One principal surface of the prism sheet 31a is provided with a shape in which a plurality of prism rows having a triangular cross section are connected.

  The step of deforming the second three-dimensional pattern from the first three-dimensional pattern is performed, for example, by extending the prism sheet 31a while applying a load in a uniaxial direction. The stretching is performed, for example, in a predetermined temperature environment where the material of the prism sheet 31a can be deformed. Here, the predetermined temperature is, for example, in the vicinity of Tg of the material of the prism sheet 31a, more specifically, for example, a range of Tg ± 40 ° C.

  For example, when a load is applied to the prism sheet 31a provided with the first three-dimensional pattern in the ridge line direction indicated by the arrow P, the prism sheet 31a extends along an axis parallel to the ridge line direction and extends in the cross-sectional direction. Shrink along parallel axes. Then, as shown in FIG. 4, the prism sheet 31a is deformed into a prism sheet 31b provided with a second three-dimensional pattern similar to the first three-dimensional pattern. As described above, the prism sheet according to the first embodiment of the present invention is manufactured.

  In the above example, the case where the first three-dimensional pattern and the second three-dimensional pattern are similar to each other has been described. However, the first three-dimensional pattern and the second three-dimensional pattern are not similar to each other. is there. In this case, for example, various shapes can be formed from one three-dimensional pattern by changing the stretching direction, the temperature condition during stretching, and the like.

  Furthermore, in the above-described example, when the prism sheet provided with the first three-dimensional pattern is stretched, a load is applied in the ridge line direction and the uniaxial stretching is performed. However, the direction in which the load is applied is not limited to the ridge line direction. For example, it is possible to form a second three-dimensional pattern in which the cross-sectional shape of the first three-dimensional pattern is deformed so as to be flattened by applying a load in the cross-sectional direction and uniaxially stretching.

  In the above-described example, the case where the prism sheet provided with the first three-dimensional pattern is manufactured by the hot press method has been described. However, the method of manufacturing the prism sheet provided with the first three-dimensional pattern is not limited to this. It is not limited to. For example, methods such as injection molding, casting, and extrusion can be used.

  As described above, in the present embodiment, the prism sheet provided with the first three-dimensional pattern transferred from one master is deformed in the uniaxial direction, and the prism sheet provided with the desired second three-dimensional pattern is obtained. Form. Thereby, a prism sheet having various three-dimensional patterns can be manufactured from one master, and an embossed sheet having a desired fine three-dimensional pattern can be manufactured without requiring high-precision precision processing on the master. Moreover, the prism sheet provided with the 2nd three-dimensional pattern of the shape similar to the prism sheet provided with the 1st three-dimensional pattern can be formed by extending | stretching along the axis | shaft parallel to a ridgeline direction.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, a prism sheet having a plurality of prism arrays each having a cross section of an isosceles triangle has been described. However, in the present embodiment, a method of manufacturing a lenticular sheet in which a large number of cylindrical lenses are provided on one main surface. Will be described.

  FIG. 5 shows an example of a lenticular sheet according to the present embodiment. As shown in FIG. 5, a large number of cylindrical lenses are provided on one main surface of the lenticular sheet 2. Since the material which comprises the lenticular sheet 2 is the same as that of the above-mentioned 1st Embodiment, description is abbreviate | omitted.

  Next, the manufacturing method of the lenticular sheet 2 by this embodiment is demonstrated. First, the lenticular sheet 2a having a large number of cylindrical lenses on one main surface is manufactured. FIG. 6 shows a cross-sectional shape of the lenticular sheet 2a.

  Next, as shown in FIG. 6, when a load is applied to the lenticular sheet 2a along an axis parallel to the cross-sectional direction indicated by the arrow T, the lenticular sheet 2a extends along an axis parallel to the cross-sectional direction. Then, as shown in FIG. 7, the first three-dimensional pattern provided on the lenticular sheet 2a is flattened to be transformed into the lenticular sheet 2b provided with the second three-dimensional pattern. As described above, the lenticular sheet according to the second embodiment of the present invention can be manufactured. In addition, extending | stretching is performed in the predetermined | prescribed temperature environment which can deform | transform the material of the lenticular sheet 2a, for example. Here, the predetermined temperature is, for example, the vicinity of Tg of the material of the lenticular sheet 2a, more specifically, for example, a range of Tg ± 40 ° C.

  In the present embodiment, a lenticular sheet 2a having a first three-dimensional pattern in which a large number of cylindrical lenses are connected to one main surface is obtained from one master, and the first three-dimensional pattern is deformed to be used for the purpose. Various second three-dimensional patterns can be obtained, and a lenticular sheet having desired orientation characteristics and visual field characteristics can be manufactured from one master. The lens body constituting the lenticular sheet is not limited to the above-described cylindrical lens body, but includes a lenticular lens body having a hyperboloid or a paraboloid, a lenticular lens body having a higher-order aspheric surface, and the like.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, a method for manufacturing a prism sheet as an embossed sheet will be described.

  In the prism sheet of this embodiment, as shown in FIG. 8A, a step of molding a resin film 23 having a prism structure surface formed on one surface, and extending the resin film 23 in the prism extending direction, The prism is manufactured through a process of reducing the cross-sectional shape of the prism to a similar shape.

  Although the molding method of the resin film 23 is not particularly limited, for example, a hot press method, a melt extrusion method, or the like is applicable. Alternatively, a flat resin sheet may be used as a base, and a prism layer may be formed thereon. In addition, the method which can produce the resin film 23 continuously by a roll system is preferable.

  The produced resin film 23 is stretched in the prism extending direction, whereby a prism sheet having a desired reduction ratio is obtained. The stretching ratio can be appropriately set according to the required reduction ratio, the type of resin film material, and the like.

  Examples of the resin material include PET (polyethylene terephthalate), PEN (polyethylene naphthalate) and a mixture thereof, or a copolymer such as a PET-PEN copolymer, polycarbonate, polyvinyl alcohol, polyester, polyvinylidene fluoride, polypropylene, polyamide, and the like. .

  Here, the reason that the extending direction is the prism extending direction is to prevent the target optical characteristics from changing due to the change in the prism shape before and after the extending. FIG. 8B shows a change in the outer shape of the prism structure surface before and after stretching. The solid line indicates before stretching, and the alternate long and short dash line indicates after stretching. By setting the stretching direction to the prism extending direction (X direction), the prism cross-sectional shape after stretching is substantially similar to the prism cross-sectional shape before stretching, so that a prism shape with a desired pitch can be obtained from one master. Can be obtained.

  On the other hand, when producing a prism sheet by stretching the resin film 23, a difference in refractive index can be provided between the stretching direction and the non-stretching direction in the plane of the prism sheet. Specifically, anisotropy of the refractive index can be generated between the prism extending direction (X direction) and the prism arrangement direction (Y direction). As a result, the transmission characteristics of light transmitted through the prism sheet can be varied according to the polarization direction due to the in-plane anisotropy of the refractive index of the prism sheet.

  As a constituent material of the resin film 23, a resin material whose refractive index increases in the stretching direction may be used, or a resin material whose refractive index decreases in the stretching direction may be used. Examples of the resin material whose refractive index increases in the stretching direction include polycarbonate, polyvinyl alcohol, polyester, polyvinylidene fluoride, polypropylene, PET, PEN, a mixture thereof, and a copolymer such as a PET-PEN copolymer. Conversely, examples of the resin material having a refractive index that decreases in the stretching direction include methacrylic resin, polystyrene resin, styrene-acrylonitrile copolymer (AS resin), styrene-methyl methacrylate copolymer, and mixtures thereof.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.

Example 1
As a metal embossed master for hot pressing, the surface is a regular isosceles triangle with a transverse cross-sectional shape of 90 degrees apex, alternating and parallel, with regular intervals of 50 μm between peaks and valleys and valleys and valleys. The one continuously engraved was used. As a thermoplastic resin, a prism sheet in which a 200 μm polycarbonate resin sheet (FE2000, Mitsubishi Engineering Plastics Co., Ltd.) is provided with a first three-dimensional pattern at a press condition of 100 kgf / cm ² (9.8 MPa) at 170 ° C. for 10 minutes. Was made.

  Next, the prism sheet provided with the first three-dimensional pattern is loaded in an oven at 160 ° C. so as to be 1 kgf / cm in the ridge direction, and then left to stand for 10 minutes to provide the second three-dimensional pattern. A prism sheet of Example 4 was obtained. In the prism sheet of this example, there was 150% expansion and contraction in the ridge line direction and 70% in the cross-sectional direction.

  Next, the cross-sectional shapes of the prism sheet before stretching and the prism sheet after stretching were measured with a surface roughness meter (Surfcoder ET4001A, manufactured by Kosaka Laboratory Ltd.) under the following measurement conditions. The cross-sectional shape of the sheet was a shape in which isosceles triangles having apex angles other than 90 degrees were regularly continuous. Furthermore, the pitch of the first three-dimensional pattern was the same 50 μm pitch as that of the master, whereas the pitch of the second three-dimensional pattern was 35 μm pitch. From this, it can be seen that a second three-dimensional pattern different from the first three-dimensional pattern can be obtained.

The measurement conditions of the surface roughness meter are shown below.
[Measurement condition]
Cut-off value R + W (mm)
Filter characteristics 2CR
Preliminary length Cut-off value Leveling None Evaluation length 1 mm
Display magnification Vertical 20000
Next 50
Feeding speed 0.02mm / s
Measuring force 50μN
In Examples 2 and 3 described below, measurement was performed under the same conditions using the same measuring machine as in Example 1.

(Example 2)
[Formation of prism sheet]
As a metal embossing master for hot pressing to transfer and form a prism shape on a resin film, the surface is alternately and parallel with a right angled isosceles triangle with a cross-sectional shape of an apex angle of 90 degrees. A trough and a trough were engraved regularly and continuously at intervals of 50 μm. The resin film was a thermoplastic resin, and a 200 μm thick A-PET (amorphous PET) sheet (“Novaclear (trademark) SG007” manufactured by Mitsubishi Chemical Corporation, Tg of about 70 ° C.) was used. This resin film was poured into ice water immediately after pressing under hot pressing conditions of 100 kgf / cm ² (9.8 MPa) at 100 ° C. for 10 minutes to obtain a transparent isotropic prism sheet.

[Extension of prism sheet]
The obtained isotropic prism sheet is cut into a rectangular shape (vertical ridge line direction) 8 cm x horizontal 5 cm, and then the triangular cross section (prism cross section) at both ends in the longitudinal direction is chucked with a manual stretching machine to extend the prism. Uniaxial stretching was performed at a stretching speed of 1 cm / sec in a warm water of 55 ° C. in the direction so that the center of the sample was 3.5 times to obtain a reduced pitch prism sheet.

  The triangular section of the obtained reduced pitch prism sheet and the isotropic prism sheet before stretching were measured with a surface roughness meter (Surfcoder ET4001A, manufactured by Kosaka Laboratory Ltd.). It was an isosceles triangle with corners. Further, the prism of the sample before stretching had a pitch of about 50 μm, which was the same as that of the master, whereas the prism of the sample after stretching had a pitch of about 30 μm.

FIG. 9 shows a schematic cross-sectional shape of the prism sheet before and after stretching. In the figure, the alternate long and short dash line indicates the cross-sectional shape of the sample before stretching, and the solid line indicates the cross-sectional shape of the sample after stretching. It can be seen that the prism is similar before and after stretching.
The two-dot chain line indicates a prism shape when a sample cut into a length of 1.5 cm and a width of 5 cm is stretched in the vertical direction (prism ridge line direction). As is apparent from the example shown in the drawing, when a sample having an aspect ratio of less than 1 is stretched in the longitudinal direction, the cross-sectional shape of the sheet is distorted and a similar prism shape cannot be obtained. Therefore, it is preferable to cut out the sample so that the aspect ratio is 1 or more.

[Measurement of birefringence]
Next, the birefringence of the obtained reduced pitch prism sheet was measured. In the birefringence measurement, as shown in FIG. 10, the polarized light is vertically incident from the prism surface of the sheet 45, the transmitted light is detected by the measuring device 46, and the prism ridge line is determined by the difference in the outgoing angle φ of the transmitted light. The difference Δn (= nv−nh) between the refractive index nv in the direction and the refractive index nh in the prism array direction was calculated. That is, the outgoing angle φ of the transmitted light varies depending on the incident polarization direction, and the outgoing angle φx of the polarization component that vibrates parallel to the prism ridge direction (hereinafter referred to as “vertical polarized light Lx”) as shown in FIG. It is larger than the emission angle φy of the polarization component that vibrates parallel to the prism arrangement direction (hereinafter referred to as “horizontal polarization Ly”). Using this, Δn can be calculated.

  FIG. 12 is a measurement result showing the relationship between the light amount of the vertically polarized light Lx and the horizontally polarized light Ly that have passed through the sheet 45 and the emission angle. The unit (a.u.) on the vertical axis is an “arbitrary unit” (arbitrary unit), which indicates “relative value”. As a result of the measurement, as shown in FIG. 13, the refractive index nx in the prism ridge direction of the obtained prism sheet 45 is 1.62, the refractive index ny in the prism array direction is 1.55, and Δn is 0.07. there were.

  From the above results, the A-PET sheet was hot-pressed to give a prism shape, and then uniaxially stretched to obtain a prism sheet with a prism pitch reduced more than that of the master while maintaining the prism-like similarity. I was able to.

  Moreover, after the A-PET sheet was hot-pressed to give a prism shape, an anisotropic prism sheet having different refractive indexes in the prism ridge line direction and the arrangement direction could be obtained by uniaxial stretching. As shown in FIG. 12, it can be confirmed that the horizontally polarized light Ly has higher transmittance than the vertically polarized light Lx. This is because the refractive index nx in the prism ridge line direction is larger than the refractive index ny in the prism array direction, so that the total reflection effect on the prism slope of the polarization component Lx parallel to the prism ridge line direction becomes higher, and the amount of transmitted light is larger than Ly. This is because it decreases.

(Example 3)
[Formation of prism sheet]
As a metal embossing master for hot pressing to transfer and form a prism shape on a resin film, the surface is alternately and in parallel with an isosceles right triangle with a cross-sectional shape of an apex angle of 90 degrees. A trough and a trough were engraved regularly and continuously at intervals of 50 μm. The resin film was a thermoplastic resin, and an A-PEN (amorphous PEN) sheet (Tg of about 120 ° C.) having a thickness of 200 μm was used. The resin film 0.99 ° C., 10 minutes, by heat pressing conditions of 100kgf / cm ² (9.8MPa), was charged immediately ice water and pressed to produce an isotropic prism sheet.

[Extension of prism sheet]
The obtained isotropic prism sheet was cut into a rectangular shape of 8 cm in length (prism extending direction) × 5 cm in width, and then the triangular cross section (prism cross section) at both ends in the longitudinal direction was chucked with a manual stretching machine. Uniaxial stretching was performed at a stretching speed of 1 cm / sec so that the center of the sample was 3.5 times in an environment of 140 ° C. in the present direction, and a reduced pitch prism sheet was obtained.

  The triangular section of the obtained reduced pitch prism sheet and the isotropic prism sheet before stretching were measured with a surface roughness meter (Surfcoder ET4001A, manufactured by Kosaka Laboratory Ltd.). It was an isosceles triangle with corners. Further, the prism of the sample before stretching had a pitch of about 50 μm, which was the same as that of the master, whereas the prism of the sample after stretching had a pitch of about 30 μm.

  FIG. 14 shows a schematic cross-sectional shape of the prism sheet before and after stretching. In the figure, the solid line indicates the cross-sectional shape of the sample before stretching, and the broken line indicates the cross-sectional shape of the sample after stretching. It can be seen that the prism is similar before and after stretching.

[Measurement of birefringence]
Next, the birefringence of the obtained reduced pitch prism sheet was measured. For the measurement of birefringence, the same measurement as in Example 2 was performed.

  FIG. 15 is a measurement result showing the relationship between the amount of light of the vertically polarized light Lx and the horizontally polarized light Ly transmitted through the prism sheet and the emission angle. The unit (a.u.) on the vertical axis is an “arbitrary unit” (arbitrary unit), which indicates “relative value”. As a result of the measurement, as shown in FIG. 16, the refractive index nx in the prism ridge direction of the obtained prism sheet 45 is 1.79, the refractive index ny in the prism array direction is 1.56, and Δn is 0.23. there were.

  From the above results, the A-PEN sheet is hot-pressed to give a prism shape, and then uniaxially stretched to obtain a prism sheet with a prism pitch reduced more than that of the master disk while maintaining the similar shape of the prism shape. I was able to.

  Moreover, the A-PEN sheet was hot-pressed to give a prism shape and then uniaxially stretched to obtain an anisotropic prism sheet having different refractive indexes in the prism ridge direction and the arrangement direction. As shown in FIG. 15, it can be confirmed that the horizontal polarization Ly has a higher transmittance than the vertical polarization Lx. This is because the refractive index nx in the prism ridge line direction is larger than the refractive index ny in the prism array direction, so that the total reflection effect on the prism slope of the polarization component Lx parallel to the prism ridge line direction becomes higher, and the amount of transmitted light is larger than Ly. This is because it decreases.

  As mentioned above, although each embodiment of this invention was described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.

  For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary.

  Moreover, in the above embodiment, although the prism sheet and the lenticular sheet were mentioned as an example and demonstrated as an embossed sheet, this invention is not limited to these. For example, the present invention can also be applied to a continuous plastic sheet provided with a light function expressed by two-dimensional expansion such as a pyramid and a cone, such as a plastic lens, a light reflection sheet, an antiglare sheet, and a diffusion sheet.

It is a perspective view which shows an example of the prism sheet manufactured by the manufacturing method of the prism sheet by the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing process of the prism sheet in which the 1st three-dimensional pattern was provided. It is the schematic for demonstrating the process of deform | transforming from a 1st solid pattern to a 2nd solid pattern. It is the schematic for demonstrating the aspect after a deformation | transformation from a 1st solid pattern to a 2nd solid pattern. It is a perspective view which shows an example of the lenticular sheet manufactured by the manufacturing method of the lenticular sheet by the 2nd Embodiment of this invention. It is sectional drawing for demonstrating the process which deform | transforms from a 1st solid pattern to a 2nd solid pattern. It is sectional drawing for demonstrating the aspect after a deformation | transformation from a 1st solid pattern to a 2nd solid pattern. It is a figure for demonstrating the manufacturing method of the prism sheet by the 3rd Embodiment of this invention. It is a figure which shows the result of having measured the cross-sectional shape of the prism sheet demonstrated in Example 2 of this invention. It is a figure for demonstrating the birefringence measuring method of the prism sheet produced in Example 2 of this invention. It is a figure for demonstrating the difference of the output angle of the perpendicularly polarized light and horizontal polarized light with respect to a prism sheet in FIG. It is a figure which shows the light transmission characteristic of the prism sheet produced in Example 2 of this invention. It is a schematic perspective view explaining the refractive index of each in-plane direction of the prism sheet produced in Example 2 of the present invention. It is a figure which shows the result of having measured the cross-sectional shape of the prism sheet demonstrated in Example 3 of this invention. It is a figure which shows the light transmission characteristic of the prism sheet produced in Example 3 of this invention. It is a schematic perspective view explaining the refractive index of each in-plane direction of the prism sheet produced in Example 3 of the present invention.

Explanation of symbols

  1, 31a, 31b ... prism sheet, 2, 2a, 2b ... lenticular sheet, 23 ... resin film, 31 ... sheet, 32 ... flat plate mold, 33 ... specular plate, 34a, 34b ... pressure plate,

Claims (8)

A process for producing an embossed sheet comprising the step of deforming an embossed sheet having a first three-dimensional pattern on one main surface in at least one axial direction to form a second three-dimensional pattern on the one main surface. Method. The method for producing an embossed sheet according to claim 1, wherein the embossed sheet is deformed in the vicinity of a glass transition point of a material of the embossed sheet. The method for producing an embossed sheet according to claim 1, wherein the second three-dimensional pattern is similar to the first three-dimensional pattern. Similar to the first three-dimensional pattern on the one main surface by extending an embossed sheet provided with the first three-dimensional pattern on one main surface along an axis parallel to the ridge line direction of the first three-dimensional pattern. A method for producing an embossed sheet, comprising a step of forming a second solid pattern having a shape. The method for producing an embossed sheet according to claim 4, wherein the first and second three-dimensional patterns are prism bodies or cylindrical lens bodies. The material of the said embossed sheet contains any one of PEN, PET, a PEN-PET copolymer, and an aramid resin. The manufacturing method of the embossed sheet of Claim 4 characterized by the above-mentioned. 5. The embossed sheet according to claim 4, wherein the embossed sheet is stretched to make a difference in refractive index between the stretching direction and the non-stretching direction in the plane of the embossed sheet having the second three-dimensional pattern. Manufacturing method. An embossed sheet provided with a first three-dimensional pattern on one main surface is stretched along an axis parallel to the cross-sectional direction of the first three-dimensional pattern, so that the second three-dimensional pattern is flattened. A method for producing an embossed sheet, comprising a step of forming a pattern.

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