WO2007037393A1

WO2007037393A1 - Process for production of multilayer films, multilayer films, and multilayer film optical elements

Info

Publication number: WO2007037393A1
Application number: PCT/JP2006/319503
Authority: WO
Inventors: Hiroyo Okamura; Tetsuyuki Iwashita; Masakazu Matsui
Original assignee: The Furukawa Electric Co., Ltd.
Priority date: 2005-09-29
Filing date: 2006-09-29
Publication date: 2007-04-05
Also published as: JPWO2007037393A1

Abstract

The invention provides a process for the production of multilayer films by subjecting a laminated film obtained by arranging two kinds of transparent thermoplastic resin films different in refractive index alternately in the thickness direction between two protective layers to pressing or rolling, more specifically, a process for the production of multilayer films which comprises arranging a laminated film obtained by laminating two kinds of transparent thermoplastic resin films different in refractive index alternately in the thickness direction between two protective layers made of a transparent thermoplastic resin to form a laminate, (i) compression-prebonding the laminate by applying such a thicknesswise pressure that the laminated film does not cause distortion or interlaminar deviation to both outside surfaces of the laminate under such temperature conditions that the laminate does not undergo thermocompression bonding to remove gas remaining in the laminate, (ii) unifying the resulting laminate through thermocompression bonding by preheating the laminate to such a temperature as to attain thermocompression bonding and applying a thicknesswise pressure within the same range as employed in the above compression prebonding to both outside surfaces of the laminate, and (iii) subjecting the obtained laminate to pressing or rolling to form a thin film.

Description

Specification

Multilayer film manufacturing method, multilayer film, and multilayer film optical element

Technical field

[0001] The present invention is obtained by disposing a laminated film obtained by alternately laminating two types of transparent thermoplastic resin films having different refractive indexes between two protective layers made of transparent thermoplastic resin. The present invention relates to a method for producing a multilayer film obtained by pressing or rolling a laminate obtained in the thickness direction, a multilayer film obtained by the production method and the like, and a multilayer optical element obtained by using the multilayer film.

Background art

[0002] Conventionally, as a method for producing a multilayer film made of a thermoplastic resin having light transmittance or light reflectivity, a process by casting, a direct method by a coextrusion method, or a multilayer film obtained by a coextrusion method is used. A method of stretching by a tensile force after lamination adhesion or a method of pressing or rolling the multilayer film is known.

For example, as a method of manufacturing an antireflection film that can prevent light reflection on the surface of a display such as a personal computer word processor, the refractive index is relatively lower than that of the support substrate on the support substrate. A layer is formed by laminating a single layer or a plurality of layers so that the uppermost layer has the lowest refractive index, and the obtained laminate is deformed by a mechanical means such as a stretching method or a press method to form a film of the laminate There is known a method for producing an antireflection film characterized by reducing the reflectance at the interface between air and a laminate by reducing the thickness (Patent Document 1). Further, as a laminated film capable of selectively reflecting light of a specific wavelength, it is a laminated film having a regularly arranged structure and having a force of 20 or more layers, and having a wavelength of 100 to 100 : A peak with a reflectance of 30% or more for the light of LOOOOOnm is observed, and the ratio of peak half-value width (w) to peak wavelength (t) (wZ t) force 0.02≤ w / t≤0. 3 (Patent Document 2) is known.

Patent Document 1: Japanese Patent Laid-Open No. 6-344487

Patent Document 2: Japanese Patent Application Laid-Open No. 2004-314570

Disclosure of the invention Problems to be solved by the invention

[0004] Since the casting process is a batch process, the manufacturing cost is high and it is not practical. In the film manufacturing method disclosed in Patent Document 1, a laminate is formed by stacking a single layer film formed by extrusion molding or 2 to 5 layers of multilayer film formed by coextrusion on a supporting substrate. When the obtained laminate is stretched by mechanical means such as pressing and rolling, the film thickness of the laminate is disturbed if a small amount of gas such as air remains between the layers of the laminate. In addition, if the adhesion between the layers of these laminates is inadequate, displacement (or slippage) occurs between the layers, resulting in non-uniform film thickness of each layer, and high reflection-type light interference color development. This is inconvenient when used for functional films such as molecular multilayer films or transmissive optical interference coloring polymer multilayer films.

Furthermore, the rolling reduction ratio of the multilayer film due to stretching [(thickness before squeezing, thickness after processing) thickness before Z-caloe] X 100 is considerably high, or the thickness of the laminate after pressing or rolling is several When the thickness is less than one hundred zm, it is difficult to form a thin film so that the thickness of each layer is almost uniform, especially when the reduction ratio of the multilayer film is 90% or more and after pressing or rolling. When the thickness of the laminated body is several hundred m or less, it is considerably difficult to form a thin film so that the thickness of each layer is almost uniform.

[0005] The laminated film disclosed in Patent Document 2 is obtained by sequentially biaxially stretching a sheet having a multi-interface structure discharged from a die or simultaneously stretching it in two directions by 2 to: LO times, and then performing a heat treatment. It is obtained. In Example 1 of Patent Document 2, after laminating with a feed block, it is supplied to a coat hanger die and formed into a sheet to obtain an unstretched laminated film of about 200 layers. It is described that a multilayer film was obtained.

However, special co-extrusion such as the feed block method is capable of simultaneously extruding about 10 layers of multi-layer film in commercial production. Commercially producing the unstretched laminated film of about 200 layers. In addition, there are difficulties associated with dealing with design changes such as multilayer film material changes, and there are also problems with considerable capital investment.

Means for solving the problem

[0006] The present invention has been made in view of the above problems, and two transparent thermoplastic resin films having different refractive indexes are alternately laminated between two protective layers made of a transparent thermoplastic resin. A laminated body obtained by placing the laminated film is preliminarily pressure-bonded and thermocompressed in advance, and then pressed or rolled in the thickness direction, the multilayer film obtained by the manufacturing method, etc. An object of the present invention is to provide a multilayer optical element obtained from a multilayer film or the like. The present invention relates to the following Embodiments 1 to 3.

[0007] That is, the present invention provides (1) a laminated film (C) in which two types of transparent thermoplastic resin films (A, B) having different refractive indexes are alternately laminated in the thickness direction. A method for producing a multilayer film (Et) in which a laminated body (E) is formed by placing between two protective layers (D) made of plastic resin, and the laminated body (E) is thinly formed by pressing or rolling. Including at least the following steps (i) to (m):

(1) Do not thermocompress the laminate (E)! Under the temperature condition, there will be no distortion or misalignment between the inner layers of the laminate film (C) in the thickness direction from both outer sides of the laminate (E). Preliminary pressure bonding below the pressure is performed to remove the gas remaining between the laminated films (C) and between the laminated films (C) and the protective layer (D).

(ii) The laminate (E) is pre-heated to a temperature at which thermocompression bonding is possible, and thermocompression bonding is performed in a state where pressure within the same pressure condition range as the pre-compression is applied in the thickness direction from both outer sides of the laminate (E). After doing so,

(iii) forming a thin film by pressing or rolling;

The present invention relates to a method for producing a multilayer film (hereinafter sometimes referred to as “Embodiment 1”).

[0008] In the "Method for producing multilayer film (Et)" of Embodiment 1, the modes described in the following (2) to (14) can be further employed.

(2) The pre-bonding is performed at a pressure of 2500 Pa or more.

(3) The pre-pressing is performed using a batch press or a rolling roller at 3000 Pa or more and half or less of the pressure during the pressing or rolling.

(4) Preheating of the laminate (E) is started before or during the pre-bonding and remains between the laminated films (C) and between the laminated film (C) and the protective layer (D) by the pre-bonding. The removal of gas is performed before reaching the temperature at which thermocompression bonding is possible.

(5) The temperature at which the thermocompression bonding is possible is as follows: (i) When the two types of thermoplastic resin films (A, B) are both amorphous resin, the center of the laminate (E) is Both types of thermoplastic resin 40-80 ° C higher than the glass transition temperature (Tg) of

(ii) When one of the two types of thermoplastic resin films (A, B) is an amorphous resin and the other is a crystalline resin, the center of the laminate (E) is the two types of heat 50 ° C. higher than the lower glass transition temperature (Tg) of the plastic rosin, and 30 ° C. lower than the melting point (Tm) of the crystalline rosin from the temperature, or

(iii) When the two types of transparent thermoplastic resin films (A, B) are crystalline resins, the laminate (E) has a melting point (Tm) at the center of the two types of thermoplastic resins. 30-50 ° C lower temperature

It is.

(6) The difference in refractive index between the two types of thermoplastic resin films (A, B) is 0.05 or more.

(7) The laminated film (C) is a laminated film formed by co-extrusion so that two types of transparent thermoplastic resin films (A, B) having different refractive indexes are alternately laminated in the thickness direction ( C 1) or a laminated film (C 2) obtained by laminating a plurality of the laminated films (C 1) so as to be alternately laminated in the thickness direction.

(8) The thickness of each thermoplastic resin film (A, B) in the laminated film (C) before pre-bonding is in the range of 5 to: L00 m, and the total number of layers of the laminated film (C) is More than 10 layers.

(9) The thickness of the two protective layers (D) in the laminate (E) before the pre-pressing is 40 to 80, respectively, and more than 0.04 times the thickness of the laminated film (C).

(10) The glass transition temperature (Tg) of the resin used in the two types of thermoplastic resin films (A, B) and protective layer (D) in the laminate (E) is different from that of crystalline resin. In the case of crystalline rosin combination, it is in the range of 20 to 150 ° C, or in the case of other combinations, 50 to 120

. It is in the range of C.

(11) The laminated film (C) in the laminated body (E) is thinned to a thickness of 1Z10 and 1Z90 by pressing or rolling once.

(12) A new protective layer (D) is newly provided on both outer side surfaces of the multilayer body obtained by thin-filming by pressing and further thinning by pressing is performed at least twice, or Lamination before pressing or rolling by combining multiple rolling rollers and rolling in multiple stages The thickness of the laminated film (C) in the body (E) is thinned to 1Z20 to 1Z300.

(13) The multi-layer body formed by thinning by one or more presses or one-stage or multi-stage rolling is further stretched by a tensile force, so that the laminate in the laminate (E) before pressing or rolling. Thin the film (C) to 1Z150 or 1Z2000.

(14) The (0 pre-compression or GiO rolling is continuously performed by performing the (0 pre-compression, GO thermocompression, and GiOi step or multi-stage rolling using a plurality of rollers.

(15) The (0 pre-compression, GO thermocompression, and GiOi stage or multi-stage rolling is performed using a plurality of roller means, and (iv) by stretching by tensile force, the (0 pre-compression or (iv) Stretching is performed continuously.

[0010] Further, according to the present invention, (16) two or more types of transparent thermoplastic resin films (A, B) having a refractive index difference of 0.05 or more are alternately laminated in the thickness direction. A laminate (E) formed by placing a laminated film (C) between two protective layers (D) made of a transparent thermoplastic resin was obtained by thin-filming by pressing or rolling. A multilayer film (Et) comprising two protective film (Dt) parts and a laminated film (Ct) part located between the two protective films (Dt),

The total thickness of the laminated film (Ct) part is 500ηπ! It is an invention relating to a multilayer film in which the thickness tends to become thinner toward the center at -100 m and the multilayer arrangement of the multilayer film (Ct) part is not disturbed (hereinafter referred to as “Embodiment 2”) Is).

In the “multilayer film (Et)” of the second embodiment, the following (17) or (20) can be adopted.

(17) The laminated film (Ct) portion is formed by laminating 20 to 500 layers in the thickness direction.

(18) The lamination accuracy ([(maximum layer thickness−minimum layer thickness) Z minimum layer thickness] X 100 (%)) in the laminated film (Ct) portion is 300% to 1500%.

(19) The lamination thickness ratio (the ratio between the maximum value and the minimum value of the resin layers having different lamination directions) in the laminated film portion (Ct) is 25 or 25.

(20) It is 60% or more at the wavelength of red, blue or green light.

[0011] Further, the present invention provides (21) a particulate multilayer optical element comprising a charged layer on both surfaces of the multilayer film according to any one of (16) to (20), A multilayer optical element is accommodated between a pair of transparent electrodes, and rotated or rotated by application to the transparent electrodes. The invention relates to a multilayer optical element that constitutes a pixel of an image display device capable of displaying an image by using reflection or transmission of light of a specific color by being capable of movement control (hereinafter, referred to as “multilayer optical device”). Or “Embodiment 3”).

The “multilayer film optical element” of the third embodiment may further have the following aspects (22) or (25).

(22) Display one of red, green, blue, cyan, magenta, or yellow.

(23) A non-light-absorbing and interference-type optical structural color body that reflects light of any one of the colors defined in (22) and transmits a complementary color for the color.

(24) The maximum external dimension is in the range of 2 μm to 200 μm.

(25) The outer shape is a plane, a cube, a convex lens, or a sphere.

The invention's effect

[0012] According to the method for producing a multilayer film (Et) of the present invention, a laminated film in which various types of transparent thermoplastic resin films (A, B) are alternately laminated between two protective layers (D). When pressing or rolling the laminate (E) in which (C) is arranged, it is possible to prevent bubbles from being entrained between layers and to prevent displacement between layers, and even in a high rolling reduction ratio, Minimal disturbance! / Multi-layer film (Et) can be manufactured stably.

In addition, the multilayer film (Et) obtained by the production method of the present invention includes a thin multilayer film including 10 layers or more, particularly 20 to 500 layers, and has a specific wavelength in the visible light region. It has excellent optical functions such as selectively and strongly reflecting the light.

Furthermore, when the multilayer film (Et) of the present invention is used for an image display element for an image display sheet, it is thin and has a high reflectance, so that a high light utilization factor can prevent a decrease in contrast and a loss of light. Since it is kept to a minimum, a bright, high-contrast, reflective electron beam can be realized. Brief Description of Drawings

[0013] FIG. 1 is an optical micrograph of a cross section of the multilayer film thinned in Example 1.

FIG. 2 is an optical micrograph of a cross section of the multilayer film thinned in Example 6.

FIG. 3 is an optical micrograph of a cross section of the laminate that was thermocompression bonded in Example 7.

FIG. 4 is an optical micrograph of the cross section of the laminate that was thermocompression bonded in Example 8. FIG. 5 is an optical micrograph of a cross section of a laminate that is thermocompression bonded in Comparative Example 2.

FIG. 6 is an optical micrograph of a cross section of a laminate that was thermocompression bonded in Comparative Example 3.

FIG. 7 is an optical micrograph of the cross section of the laminate that was thermocompression bonded in Comparative Example 4.

FIG. 8 is an optical micrograph of the cross section of the laminate that was thermocompression bonded in Comparative Example 5.

[FIG. 9] Conceptual diagram of a device that can apply a voltage to electrodes existing on the inner surface of a spacer by arranging multilayer optical elements in silicone oil in the spacer. The best form to do

[0014] Embodiments 1, 2, and 3 of the present invention will be described below.

Before the pressing or rolling, the laminated film (C) refers to a laminate in which two types of transparent thermoplastic resin films (A, B) are alternately laminated in the thickness direction. ) Means that a laminated film (C) is disposed between two protective layers (D).

In the description of the comparative example, the protective film (D) may be provided only on one outer surface of the laminated film (C), and the laminated body (E) t may be used.

The laminate (E) is thinned by the pressing or rolling into a multilayer film (Et). The laminated film (C) part and the part corresponding to the protective layer (D) part constituting the laminated body (E) are thinned by the press or rolling, or laminated film (Ct) part by thinning and stretching, respectively. Protective film (Dt) part.

When the operation of thinning by pressing is performed twice or more, the protective layer (D) newly added to the structure thinned once (hereinafter sometimes referred to as a multilayer body) is the first after the pressing. It is integrated with the protective layer (D) used before pressing by thermocompression bonding to form the protective film (Dt).

[0015] [1] Embodiment 1

In Embodiment 1, a laminated film (C) in which two types of transparent thermoplastic resin films (A, B) having different refractive indexes are alternately laminated in the thickness direction is made of a transparent thermoplastic resin 2 A multilayer film (Et) manufacturing method in which a laminated body (E) is formed by being disposed between two protective layers (D), and the laminated body (E) is thinly formed by pressing or rolling. Including step (i), and (iii),

(i) Do not thermocompress the laminate (E)! Under the temperature condition, there will be no distortion or misalignment between the inner layers of the laminate (C) in the thickness direction from both outer sides of the laminate (E). Less than pressure Remove the remaining gas between the laminated film (C) and between the laminated film (C) and the protective layer (D) by pressure bonding.

(iii) forming a thin film by pressing or rolling;

The invention relates to a method for producing a multilayer film.

That is, in the method for producing a multilayer film (Et) in the present invention, a thin film is formed by forming a laminate (E) comprising a laminated film (C) and a protective layer (D), pre-compression bonding, thermocompression bonding, and pressing or rolling. , Consisting of processes.

The multilayer film (multilayer body) obtained from the thin film can be further stretched by a tensile force.

The force assumed to be accompanied by stretching in the thin film formed by pressing and rolling in Embodiment 1 In this specification, the processing by pressing or rolling is made thin, and the processing by tensile force using a chucking means is stretched! Uh.

(1) Laminated film (C), (2) Protective layer (D), and (3) Laminated body (E), and (4) Pre-compression, (5) Thermocompression, (6) Thin film formation, (7) stretching, and (8) multilayer film (Et) will be described.

(1) Laminated film (C)

Specific examples of the thermoplastic resin used for the laminated film (C) and the protective layer (D) of the present invention will be described later, but two types of transparent thermoplastic resins different in refractive index from the laminated film (C). Films (A, B) are arranged alternately in the thickness direction.

The laminated film (C) is preferably a laminated film (C1) formed by coextrusion so that the thermoplastic resin films (A, B) are alternately laminated in the thickness direction, or the laminated film (C 1) Is a laminated film (C2) in which a plurality of layers are laminated so as to be alternately laminated in the thickness direction.

The total number of layers of the laminated film (C) is preferably 10 or more, more preferably 20 to 500, from the viewpoint of optical properties. In particular, the light reflection characteristics required for a multilayer film (Et) are two types of grease. Since it is determined by the difference in folding ratio, the thickness of each layer in the multilayer film, and the number of layers, the number of layers can be practically determined by the required design capability.

[0017] The two types of transparent thermoplastic resin films (A, B) used for the laminated film (C) preferably have a refractive index difference of 0.05 or more, more preferably 0.1 or more. When the multilayer film (Et) obtained by the production method of the present invention has functions such as light reflection and interference, the refractive index difference is preferably 0.05 or more, and the refractive index difference is 0.05 or more. Alternatively, a multilayer film obtained by rolling a thin film, and a high reflectance can be obtained even when the number of laminated layers is 500 or less. Further, considering the coextrusion property, pre-compression bonding and thermocompression bonding in the present invention, the heat treatment property of the thin film, the heat resistance of the multilayer film (Et), etc., the glass transition temperatures (Tg) of the above two types of resins. The glass transition temperature (Tg) of the two types of thermoplastic resin films (A, B) and protective layer (D) used in the laminate (E) are crystalline resin and amorphous resin. In the case of a combination of natural rosin, it is desirable to be in the range of 20 to 150 ° C, or in the case of other combinations, it is desirable to be in the range of 50 to 120 ° C. Further, from the viewpoint of processability in the above-mentioned case, the melt viscosity ratio of the two types of resins is preferably 1 to 6, particularly 1 to 3.

In addition, it is desirable to select two types of thermoplastic resin films (A, B) to be used that do not dissolve each other in the processing conditions of coextrusion, pre-compression bonding and thermocompression bonding, and thin film. When melted together, a new molten layer appears between the laminated films (C), and light refraction occurs at the interfaces on both sides of the new layer.

[0018] The thickness of each layer of the laminated film (C) in the laminate (E) is not particularly limited, but thermocompression bonding, processability of the thin film, thickness of the multilayer film after thinning (or stretching), etc. Is considered to be in the range of 5 to: LOO / zm, and further 20 to 50 / ζ πι. Such a thermoplastic film can be laminated by arbitrarily laminating one obtained as a single layer or a multilayer film by extrusion molding or coextrusion molding to obtain a laminated film (C).

The total thickness of the laminate (Ε) is the sum of the thickness of the protective layer (D) described above and the thickness of the laminate film (C).

[0019] The two types of thermoplastic resin films (Α, Β) used in the present invention are appropriately selected in accordance with the performance required for the multilayer film (Et), and the amorphous resins and crystals ! / And misalignment of the functional resin can also be used. A preferred combination is between non-crystalline coconut resins or crystalline rosin Considering the difference in refractive index and the combination of resins with poor compatibility, the combination of amorphous resin is more preferable.

Examples of the transparent thermoplastic resin for the laminated film (C) include the following: In the present invention, the resin is not limited to these resins.

(i) As amorphous resin, polystyrene, polyvinyl chloride, ABS resin, AS resin, methyl polymethacrylate, polysylvinylidene, polycarbonate, modified polyphenylene ether, polysulfone, polyethersulfone, poly Examples include arylate, polyamideimide, polyetherimide, and polyimide.

[0020] In addition, the following can be cited as amorphous talylate-based fats. The numerical values in Katsuko indicate the refractive index, and the last numerical value indicates the glass transition temperature (Tg) (° C ).

Poly (t to butyl metatalylate) [1.464, 60], polyisopropyl metatalylate [1.473, 8 1], polyisobutyl metatalylate [1.477, 60], polybutyl butyral [1.485, 49], polymethyl Methacrylate [1.489, 105], Polybutyl alcohol [1.51, 85], Polycyclohexylmethacrylate [1.507, 83], Poly (2-hydroxyethyl methacrylate) [1.512, 55], Polyisopropyl methacrylate 1.552, 81], poly (p-isopropylstyrene) [1.554, 87], polybenzyl methacrylate [1.568, 54], polyphenyl methacrylate [1.571, 110], polystyrene [1.591, 100]

(ii) Examples of crystalline resin include polyethylene, polypropylene, polymethylpentene, polybutyl alcohol, polyvinylidene fluoride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, and polyether ether ketone. Can be mentioned.

(iii) Among the thermoplastic resins described above, considering the difference in refractive index, melting point, glass transition temperature, melt viscosity ratio, etc., various combinations can be considered. Preferred examples include polystyrene and polymethylmethacrylate-based resin. And polycarbonate and polymethylpentene.

[0021] (2) Protective layer (D)

The protective layer (D) is disposed on both outer side surfaces of the laminated film (C) and functions as a layer for protecting the laminated film (C) during preliminary pressure bonding, thermocompression bonding, and thin film bonding. Ie protective layer By providing (D), it is possible to remarkably reduce the disorder of the layer of the laminated film (C) when thinned by pressing or rolling, and to significantly increase the rolling reduction in thinning processing. Become.

As described above, when the laminated film (C) has a large number of layers and has a thickness corresponding thereto, the protective film (D) is provided on both outer sides of the laminated film (C), and the thin film is formed by pressing or rolling. Not only can the wrinkle processing be very easy, but also the rolling reduction can be increased to obtain a desired film thickness.

The protective layer (D) for protecting the laminated film (C) is preferably a resin that is equal to or slightly harder than the laminated film (C) for pre-compression and thermocompression bonding. Further, from the viewpoint of protecting the laminated film (C), each thickness of the protective layer (D) does not have a light interference function! /, More preferably about 40 μm or more, particularly preferably a thickness of about a certain degree. Is 40 to 800 μm, or more preferably 0.04 times or more, and particularly preferably 0.05 times or more of the thickness of the laminated film (C).

If the thickness of the protective layer (D) does not have an optical interference function, it can be achieved by setting the thickness to a thickness. The function as the layer (D) is more satisfactorily exhibited. In terms of practical surface strength, the thickness of the protective layer (D) is more preferably 40 μm or more, more preferably 100 μm or more. Also, even if the thickness of the protective layer (D) exceeds 800 m, improvement in its function cannot be expected, and there is little need for a thickness exceeding 800 μm from the economical aspect.

Since the protective layer (D) is pre-heated and thermocompression bonded as the laminate (E) at the same time as the laminate film (C), from the viewpoint of workability, the glass transition temperature (Tg) has two types of thermoplastic resin films ( It is desirable to be the same as A and B). From the above viewpoint, the transparent thermoplastic resin used in the protective layer (D) can be appropriately selected from the two types of thermoplastic resin films (A, B) used.

(3) Laminate (E)

If the two types of thermoplastic resin films are A and B and the protective layer is D, the layer structure of the stack (E) can be DZAZBZ AZBZAZD.

/ Β / · · · 'A / B / D. In order to obtain a high pressing ratio by pressing, new protective layers (D) are provided on both outer surfaces of the multilayer body obtained after one thin film forming, and the thin film is further stretched by pressing. It is also possible to do this. The protective layer (D) provided on both outer sides of the multilayer body after the second time can use the same thermoplastic resin as that first provided on both outer sides of the laminated film (C). Is determined in consideration of the compression ratio and the like.

[0023] (4) Pre-crimping

By removing the gas remaining in the laminate (E) before pressing or rolling, gas is entangled between the layers of the multilayer film (Et) obtained by pressing or rolling, and the multilayer film is disturbed. Can be remarkably prevented.

Pre-compression is a pressure that does not cause strain or displacement between the inner layers of the laminate (E) in the thickness direction from the outer side surfaces of the laminate (E) under the temperature conditions where the laminate (E) is not thermocompression bonded. This is a process to remove the gas remaining between the laminated film (C) and between the laminated film (C) and the protective layer (D) by pre-pressing below the force, and in this way to the laminated body (E) etc. The operation of applying force or pressure is sometimes referred to as pressurization or preload in the technical field or other technical fields.

Remove the remaining gas between the laminated film (C) and between the laminated film (C) and the protective layer (D) under the pressure without causing pre-crimping to the laminated film (C) or causing the displacement between the inner layers. Thus, a desired multilayer film (Et) can be stably produced, and a multilayer film (Et) having an excellent optical function can be obtained.

[0024] The pre-bonding conditions are 2500 Pa or more in the thickness direction from a practical aspect and not more than half of the pressure of the press or rolling, preferably 2500 to 10,000 Pa, more preferably 250 0 to 8000 Pa, Especially preferred <is 3000-6000Pa.

It should be noted that the temperature of the laminate (E) in the pre-compression is effective at about room temperature (25 ° C.) as long as the thermocompression does not proceed. In addition, the temperature of the layered product (E) during pre-bonding is preferably maintained below the glass transition temperature Tg of each of the two types of resin used from the viewpoint of preventing deformation.

The pre-compression time depends on the shape of the laminate (E) (its length, width, number of layers, etc.) and the material properties (hardness of the laminate film (C) and protective layer (D), etc.). I ca n’t decide However, there is no particular problem if a time slightly longer than the time required for removing the remaining gas is set.

There is no particular limitation on the apparatus used for the pre-pressing means in the pre-pressing, but a batch type press or a rolling roller can be used. Considering preheating for thermocompression bonding, a device capable of both precompression bonding and preheating is desirable.

[0025] (5) Thermocompression bonding

The purpose of thermocompression bonding in Embodiment 1 is that, when thin film is formed by pressing or rolling, deviation occurs between the laminated films (C) and between the laminated film (C) and the protective layer (D). This is to prevent disturbance between the layers.

In thermocompression bonding, the laminate (E) is preheated to a temperature at which thermocompression bonding can be performed, and both outer surface forces of the laminate (E) are applied with pressure within the same pressure condition range as that of the precompression bonding in the thickness direction. The laminated body (E) is integrated by thermocompression bonding.

In this case, “thermocompression bonding” means that each resin layer is melted and polymerized by pressing and preheating at the interface between the laminated films (C) and between the laminated film (C) and the protective layer (D). When the film is thermocompression bonded without moving to each other, that is, when thinned or stretched by pressing or rolling, between the laminated films (C) and between the laminated films (C) and the protective layer ( D) In the meantime, there is almost no deviation.

Preheating for thermocompression can be started after pre-compression, but if the residual gas in the laminate (E) is removed before reaching the temperature at which thermocompression bonding is possible, the pre-compression or pre-compression can be performed. You may start preheating the laminate (E) during pre-crimping! / ヽ.

The temperature at which the thermocompression bonding can be performed is preferably the following (i) or (iii), but the physical properties of the thermoplastic resin to be used and the laminate (E It may be difficult to make a uniform decision because it depends on the configuration of (), so it may be necessary to confirm by experiments assuming a thin film stack (E).

(i) When the two types of thermoplastic resin films (A, B) are both amorphous resin, the center of the laminate (E) is the glass transition of both of the two types of thermoplastic resins. 40-80 ° C higher than temperature (Tg)

(ii) One of the two types of thermoplastic resin films (A, B) is amorphous resin and the other is crystalline resin In the case of a fat, the central part of the laminate (E) is 50 ° C. higher than the lower glass transition temperature (Tg) of the two types of thermoplastic resin, and the temperature of the crystalline resin is determined from the temperature. 30 ° C below the melting point (Tm)

Under the above conditions (i) to (iii), the heat resistance can be maintained at a temperature equal to or higher than the lower limit of each temperature range. Without maintaining the layer structure.

In the present invention, the glass transition temperature (Tg) (° C.) is a midpoint glass transition temperature measured by the DSC method (differential scanning calorimetry, heating rate 10 ° C / min). (Tmg), melting point (Tm) (° C.) are melting points measured by DSC method (differential scanning calorimetry, heating rate 10 ° C / min). These values can be measured using, for example, DSC (model 3100) manufactured by Mac 'Science Co., Ltd.

Note that the temperature difference between the glass transition temperature (Tg) and the melting point (Tm) of typical crystalline plastics is about 175-210 ° C, so the fusing phenomenon does not occur in the temperature range 50-100 ° C higher than Tg. Generally does not occur. In addition, when the two types of thermoplastic resin films (A, B) are crystalline resin, fusion is performed at a temperature 30 to 50 ° C. lower than the melting point (Tm) of both of the two types of thermoplastic resins. The phenomenon generally does not occur.

[0028] When the preheating temperature is raised above the above-mentioned temperature range to near the melting point, a laminated film

A new molten layer appears between (C), and there is a possibility that light refraction occurs at the interfaces on both sides of the new layer.

As long as the pressure condition for thermocompression bonding is the same as that for pre-compression, the pre-compression pressure can be maintained as it is.

Preferable thermocompression bonding The range of pressure conditions varies depending on the physical properties of the thermoplastic resin used and the composition of the laminate (E), so it is difficult to determine uniformly, but pre-compression is performed at a higher pressure. In some cases, preheating to a temperature at which thermocompression bonding can be performed with the same pressure may cause distortion that impairs the optical function or displacement between layers. In some cases, it may be safer to set the upper pressure limit lower than when pre-bonding.

The preheating time depends on the combination of the resin used and the thickness of the laminate (E), but when the center temperature of the laminate (E) reaches a predetermined temperature and a press is used, it takes several minutes or more. In the case of rolling for about 1 to 30 minutes, a shorter time may be used. When using a press, for example, when the thickness of the layered product (E) is 1000 μm, about 20 minutes is preferable.

There are no particular restrictions on the preheating means for preheating for thermocompression bonding, but examples include a hot plate, a hot press plate, a thermostatic bath, a non-contact infrared heater, and the like.

[0029] (6) Thin film

The thin film is a process in which the laminated film (C) after thermocompression bonding is thinned by pressing or rolling using a known method or the like. In the thin film substrate of Embodiment 1, even if a thin film substrate is used because of the preliminary process, that is, preliminary crimping and thermocompression, each layer in the laminate (E) is not disturbed. The laminated film (C) can be thinned to a thickness of 1Z10 to 1Z90 by stretching by one press or rolling.

In particular, in the thin film substrate of Embodiment 1, at least twice the operation of providing a new protective layer (D) on both outer side surfaces of the multilayer body obtained by thin film formation by the press and further performing the thin film formation by press. By carrying out the above, or by rolling in multiple stages by combining a plurality of the above rolling rollers, the thickness of the laminated film (C) part in the laminate (E) before pressing or rolling is reduced to 1Z20 or 1Z300. It is possible.

For thin films, it is desirable that the press or rolling pressure be within the range of preheating temperature in thermocompression bonding.

When using a press machine in a thin film, it is possible to perform stretching by pressing continuously without releasing the pressure after thermocompression bonding, while stretching by force pressing with the pressure released gradually. Also good.

By performing the (0 pre-compression, GO thermocompression bonding, and (m) i-stage or multi-stage rolling using a plurality of rollers, the (0 pre-compression or GiO rolling can be performed continuously.

[0030] (7) Stretching

In the present invention, after the thinning, the stretching can be further performed by a tensile force of a chucking means or the like. For example, (0 pre-compression, GO thermocompression bonding, and (m) i-stage or multi-stage rolling is performed using a plurality of one roller means, and Gv) is stretched by a tensile force such as a chucking means. The (0 pre-compression or Gv) stretching can be performed continuously. In particular, in the process of continuously performing the stretched thin film, it is advantageous that the stretch ratio can be controlled inline while confirming the color development.

In addition, stretching by a tensile force can be performed not by a continuous process but by a batch process. Stretching in the batch process may be performed once or may be performed a plurality of times. The stretching direction and the number of stretching can be freely selected as necessary. In addition, stretching in the batch process may be performed biaxially at the same time.

As a draw ratio, it can be carried out in a range of 2 to 4 times in each direction by one stretch. The multilayer body thinly formed by one or more presses or one-stage or multi-stage rolling is further stretched by a tensile force to obtain a laminated film (C) in the laminate (E) before pressing or rolling. The thickness of the) portion can be reduced to 1Z150 to 1Z2000.

(8) Multilayer film (Et)

The multilayer film (Et) obtained by force is a multilayer film (Et) composed of two protective film (Dt) parts and a laminated film (Ct) part located between the two protective film (Dt). is there.

The ratio of the laminated film (C) used for thinning and the thickness of the thin film can be appropriately selected according to the use of the target multilayer film (Et).

The multilayer film (Et) obtained by the thin film is arranged in the thickness direction of 10 layers or more, especially 20-500 layers, and the total thickness of the multilayer film is 500ηπ! It can be up to 500 μm.

The lamination thickness ratio in the laminated film (ratio between the maximum value and the minimum value of the resin layers with different lamination directions) is usually 1 to 5, but in the production method of the multilayer film (Et) of the present invention, it is 1 to 25. Can also be used sufficiently for applications such as color bodies.

The lamination accuracy in the laminated film ([(maximum layer thickness to minimum layer thickness) Z minimum layer thickness] X 100 (%)) is preferably smaller, but in the method for producing the multilayer film (Et) of the present invention, it is not 300%. It has functions such as coloring even with a stacking accuracy in the range of 1500%. It is also possible to obtain a multilayer film (Et) having a reflectance of 60% or more at the wavelength of red, blue, or green light. In addition, when the protective layer (D) is provided on both outer side surfaces of the laminate described in Embodiment 1 to form a thin film, when the manufacturing method is adopted, the thickness of the multilayer film (Et) is reduced toward the center direction ( In particular, this tendency becomes more prominent when the thickness of the protective layer (D) is increased), and it is possible to obtain a layer in which the arrangement of each layer in the laminated film (Ct) portion is not disturbed. Such a multilayer film (Et) has been known so far and is a new and useful multilayer film.

[0032] [Embodiment 2]

In the multilayer film (Et) according to Embodiment 2, two or more types of transparent thermoplastic resin films (A, B) having a refractive index difference of 0.05 or more are alternately laminated in the thickness direction. A laminate (E) formed by placing the laminate film (C) between two protective layers (D) made of a transparent thermoplastic resin was obtained by thin-filming by pressing or rolling. A multilayer film (Et) comprising two protective film (Dt) parts and a laminated film (Ct) part located between the two protective films (Dt), wherein the total thickness of the laminated film (Ct) part Is 500ηπ! The multilayer film (Et) according to Embodiment 2 is characterized in that the thickness tends to become thinner toward the center direction at -100 m and the multilayer arrangement of the multilayer film (Ct) part is not disturbed. For example, the laminated film (C) described in Embodiment 1 in which two types of transparent thermoplastic resin films (A, B) having different refractive indexes are alternately laminated in the thickness direction is used as a transparent thermoplastic film. It is a multilayer film (Et) obtained by forming a laminated body (E) by placing it between two protective layers (D) made of fat, and forming this laminated body (E) into a thin film by pressing or rolling. .

Therefore, portions corresponding to the laminated film (C) portion and the protective layer (D) portion constituting the laminated body (E) in Embodiment 1 are thinned by the pressing or rolling, respectively, and the laminated film in Embodiment 2 is used. (Ct) part, protective film (Dt) part.

From the above, the laminated film (Ct) part and the protective film (Dt) part in Embodiment 2 are the materials used for the laminated film (C) part and protective layer (D) part described in Embodiment 1. It is the same.

Up to now, two types of thermoplastic resin films (A, B) with different refractive indexes between two protective layers (D), or a film in which these layers are laminated, are arranged alternately in the thickness direction by about 20 to 500 layers. The total thickness of the laminated film (Ct) part is 500ηπ! As a multilayer structure of about 100 μm, for example, JP 2004-122764 A uses a feed block as a packaging material. After laminating the layers, a laminated film having a thickness of 129 layers and a thickness of 50 μm is disclosed using a square mixer. In Patent Document 2, two types of thermoplastic resin are used in a feed block. After joining the layers, it was supplied to the coat hanger die, formed into a sheet, then stretched longitudinally 3 times with preheating, and transversely stretched 3.5 times to obtain a film with a thickness of 18 / zm Is written.

[0034] In the known coextrusion method, the laminate (E) is stretched by tensile force, or the laminate (E) is stretched by pressing or rolling, and 20 to 500 layers are alternately arranged in the thickness direction. Thus, it is not known that the total thickness of the laminated film (Ct) part is 500 nm to 100 μm and the arrangement of each layer is not disturbed.

In addition, in the known coextrusion method, the laminate (E) is stretched by a tensile force and is laminated between the protective layers (D), and the thickness of the film tends to become thinner in the central direction. And there was no disturbance in the arrangement of each layer.

In addition, “the thickness of the laminated film tends to be thinned in the central direction” between the protective layers (D) in the multilayer film (Et) of the present invention means that the thickness of the film is in the center. It is not required to be so strict as to be evenly thinned, so long as the tendency shown in the cross-sectional photograph of FIG.

[0035] The ratio of the laminated film (C) to be used in the thin film and the thin film is appropriately selected in accordance with the use of the multilayer film (Et) which is the target product. The multilayer film (Et) obtained by the thin film of the present invention has 10 or more layers, particularly 20 to 500 layers arranged in the thickness direction, and the total thickness of the laminated film (Ct) part is 500 ηm to 100 μm. Is possible.

The lamination accuracy ([(maximum layer thickness−minimum layer thickness) Z minimum layer thickness] X 100 (%))) in the laminated film is preferably small, but in the present invention, the lamination accuracy is 300% or more and 1500% or less. It has sufficient functions such as coloring.

[0036] When the multilayer film (Et) is used in a structure that develops a specific color, whether to develop red, green, blue, or the like depends on the thickness of each layer and the refractive index of each layer. Easy to design The strength of the multilayer film can be increased by increasing the number of layers of the multilayer film. Therefore, the thickness per layer of the layered product (E) and the reduction ratio in stretching by pressing or rolling may be arbitrarily selected according to such a design. The multilayer film (Et) thus obtained can have a reflectance of 60% or more at light wavelengths such as red, blue, and green.

[0037] [3] Embodiment 3

The multilayer optical element according to Embodiment 3 is a particulate multilayer optical element in which charged layers are provided on both surfaces of the multilayer film (Et) described in (15) to (19), The film optical element is accommodated between a pair of transparent electrodes, and rotation or movement can be controlled by application to the transparent electrodes, so that an image can be displayed using reflection or transmission of light of a specific color. The pixel of the image display apparatus which can be performed is comprised.

The present inventors previously filed a patent application (Japanese Patent Application No. 2004-111548, hereinafter referred to as “previous application”) relating to “image display element, image display sheet, image display device and image display method”. The multilayer film (Et) of the present invention can be suitably used for the image display element of the previous application.

That is, since the multilayer optical element in which the charge layers are provided on both outer side surfaces of the multilayer film (Et) described in Embodiment 2 is excellent in light reflectivity, it is excellent as an image display element for an image display sheet. It has a function.

[0038] The multilayer optical element of the present invention can be obtained by arbitrarily designing the refractive index difference between the two types of thermoplastic resin and the thickness of each layer in the multilayer film, so that red, green, blue, cyan, magenta, Alternatively, the color development of yellow can be designed, and the color intensity can be increased by increasing the number of layers in the multilayer film. Therefore, the multilayer optical element formed using the multilayer film (Et) of the present invention is It is easy to display any one of red, green, blue, cyan, magenta, or yellow.

The multilayer optical element of the present invention can be a non-light-absorbing and interference-type optical element that reflects light of any one of the colors and transmits a complementary color to the color, and is an image display sheet. When used as an image display device, a flat, cube, sphere, or convex lens shape (where the center of the convex lens is near the center) is preferred to have a maximum outer dimension of 2 μm to 200 m. (Including those that are formed in a planar shape) It is preferable to use.

Example

[0039] Hereinafter, the present invention will be described by way of examples.

In addition, this invention is not limited to a following example.

(1) Used materials

(i) Polystyrene

Product name: PSJ-polystyrene, refractive index: 1.59, Tg: 100 ° C, manufactured by PS Japan

(ii) Polymethylmetatalylate resin

Made by Mitsubishi Rayon Co., Ltd., trade name: Ataripet, refractive index: 1.49, Tg: 105 ° C

(iii) Polycarbonate

Product name: Panlite, Refractive index: 1.585, Tg: 145 ° C, manufactured by Teijin Chemicals Limited

(iv) Polymethylpentene

Product name: TPX, refractive index: 1. 463, Tg: 25 ° C, Tm: 235 ° C [0040] (2) Evaluation method

(i) Glass transition temperature (Tg), melting point (Tm)

The glass transition temperature (Tg) (° C.) was measured by the DSC method (differential scanning calorimetry, heating rate 10 ° / min). The melting point (Tm) was similarly measured by the DSC method (differential scanning calorimetry, ascending rate 10 ° C / min).

(ii) Evaluation by reduction ratio

The reduction ratio is obtained from the following formula from the thickness before and after the processing.

Definition of rolling reduction: [(Thickness before processing Thickness after processing) Thickness before Z processing] X 100

(iii) Evaluation by stacking accuracy

The stacking accuracy is obtained from the following formula from the maximum layer thickness and the minimum layer thickness in the multilayer film. Definition of stacking accuracy: [(maximum layer thickness minimum layer thickness) Z minimum layer thickness] X 100 (%)

(iv) Observation of cross-sectional structure of laminate and multilayer film

Images were taken with a scanning electron microscope (SEM).

When the cross section of the laminate and the multilayer film was processed, it was coated with a transparent epoxy resin as an embedded resin. [0041] [Example 1]

(1) Production of multilayer film

(i) Formation of laminate

Polystyrene and polymethylmethallate resin were used as materials for the thermoplastic resin film. Using a co-extruder, a two-layer film having a thickness of about 38 μm was obtained from each thermoplastic resin. The resulting two-layer film was laminated in layers so as to form 50 layers, and polystyrene (with the same resin as the polystyrene used for the thermoplastic resin film) having a thickness of 100 m on both outer layers was used as a protective layer. Arranged to obtain a laminate

(ii) Pre-crimping

The laminate was pre-pressed by applying a load of 25 ° C. and a load of 5600 Pa at a temperature of 25 ° C. for 30 seconds with a batch press to remove air remaining between the layers of the laminate.

(iii) Thermocompression bonding

Maintain the load of 5600 Pa in pre-crimping, preheat the laminate from both sides with an electric heater, and maintain for 20 minutes after the center of the laminate reaches 160 ° C. The interface was integrated by thermocompression bonding.

[0042] (iv) Pressing process

The integrated laminate was pressed for the first time for 1 minute at a temperature of 160 ° C. and a pressure of 19.4 MPa using a batch press. Next, in order to perform the second press, the multilayer body (thickness: 185 m) obtained in the first press is used for two protective layers (thickness: 185 m) each with a thickness of 400 μm. The thickness is 985 m. The multilayer body provided with a protective layer was pressed a second time under the same conditions as above to obtain a multilayer film having a thickness of 90 m.

In the first press, the total thickness of the laminate was reduced to 2165 μm force 185 μm, the rolling reduction was 91.5%, and the first rolling reduced the thickness to 1Z11.7.

At this time, for the laminated film part, the thickness per layer decreased from about 38 m (average thickness) to about 3 m (average thickness), the rolling reduction was 92.1%, and the thickness was 1Z12.7. Turned into In the second press, the thickness of the multilayer body and the protective layer decreased to 985 μm force to 90 μm, the reduction ratio was 90.9%, and the second rolling reduced the thickness to 1Z10.9.

At this time, the thickness per layer of the laminated film part is reduced from about 3 m (average thickness) to about 130 nm (average thickness), the rolling reduction is 95.7%, and the thickness of the thin film is 1Z23. I was deceived.

As a result of the above-mentioned two times of thin film, the thickness per layer of the laminated film portion of the laminate was reduced from about 38 m (average thickness) to about 130 nm (average thickness), and was thinned to a thickness of 1Z292.

[0043] (2) Evaluation of multilayer film

(i) The cross-sectional structure of the multilayer film obtained after the second pressing was taken with a scanning electron microscope (SEM). It was confirmed that the thickness of the laminated film portion in the multilayer film tended to become thinner in the direction of the center, and the disorder of the laminated arrangement of each layer was extremely small.

The lamination accuracy was 1000% or more, and the lamination thickness ratio was 20.

(ii) The reflected light of the obtained multilayer film has a peak at the blue wavelength, and the reflectance is 60% or more.

[0044] [Example 2]

(1) Production of multilayer film

(i) Pre-crimping, thermocompression bonding

In Example 2, the laminate obtained in Example 1 was used, the load in the pre-compression was set to 3 OOOPa, and the load in the pre-compression was maintained as it was in the thermocompression bonding. And thermocompression bonded.

(ii) Press

After the thermocompression bonding, a multilayer film was obtained by thin film forming with a batch press.

In Example 2, the total thickness of the laminate was reduced from 2267 μm force to 165 μm by the first press, the rolling reduction was 92.7%, and the thickness was reduced to 1Z13.7 by the first rolling. It was. At this time, for the laminated film part, the thickness per layer decreased from about 38 m (average thickness) to about 2 m (average thickness), the rolling reduction was 94.7%, and the thickness of 1Z19 Was When performing the second press, a protective layer having a thickness of 400 m was added on both sides. More of the second press, the first of reduced total thickness 965 μ m or et al 78 / zm [this protective layer has been added to the multi-layer body obtained in the press, at a reduction rate ί or 91.9 ^_0/0, 2 Rolling of the second round [Thickness of 1/12. 4]

At this time, for the laminated film part, the thickness per layer is reduced from about 2 m (average thickness) to about 160 nm (average thickness), the rolling reduction is 92%, and the thickness is reduced to 1/12. I was deceived.

The above two thin films reduce the thickness of each layer of the laminated film from about 38 m (average thickness) to about 160 nm (average thickness), reducing the thickness to 1 / 2377.5. It was done. (2) Evaluation of multilayer film

As in Example 1, the cross-sectional structure of the multilayer film obtained after the second press was observed with a scanning electron microscope (SEM). It was confirmed that the thickness of the laminated film portion in the multilayer film obtained in Example 2 tended to be thinned in the direction of the center, and there was very little disturbance in the laminated arrangement of each layer.

[0045] [Example 3]

(1) Production of multilayer film

Example 3 is the same as Example 1 except that the laminate obtained in Example 1 was used, the pre-compression load was set to 4500 Pa, and the pre-compression load was maintained as it was during thermocompression bonding. Thus, a multilayer film was manufactured.

(2) Evaluation of multilayer film

As in Example 1, the cross-sectional structure of the multilayer film obtained after the second press was observed with a scanning electron microscope (SEM). It was confirmed that the thickness of the laminated film portion in the multilayer film obtained in Example 3 tended to become thin in the direction of the center, and that there was very little disturbance in the laminated arrangement of each layer.

[Example 4]

(1) Production of multilayer film

In Example 4, using the laminate obtained in Example 1, pre-crimping was conducted in the same manner as in Example 1 except that the preheating of the laminated film by the electric heater during preheating was set to 175 ° C. heat A multilayer film was obtained by pressure bonding and pressing.

(2) Evaluation of multilayer film

As in Example 1, the cross-sectional structure of the multilayer film obtained after the second press was observed with a scanning electron microscope (SEM). It was confirmed that the thickness of the laminated film portion in the obtained multilayer film product tended to be thinned in the central direction, and that there was very little disturbance in the laminated arrangement of each layer.

[0047] [Example 5]

(1) Production of multilayer film

The following laminate was continuously subjected to preliminary pressure bonding, thermocompression bonding, and rolling using a roller to obtain a multilayer film.

(i) Formation of laminate

Co-extruded polystyrene and polymethylmetatalylate resin, each layer has a thickness of about 20 μm, and each layer has a thickness of 30 layers. A laminate having a thickness of 40 / zm (the same resin as the polystyrene used for the thermoplastic resin film) was disposed as a protective layer.

(ii) Pre-crimping

The laminate was pre-pressed by applying a load of 3000 Pa at a temperature of 25 ° C. for about 15 seconds using a roller to remove air remaining between the layers of the laminate.

[0048] (iii) Thermocompression bonding

Maintain the load of 3000Pa in the pre-compression, preheat the laminate in the hot air furnace, reach the center of the laminate at 160 ° C and maintain the force for 15 minutes, and maintain the interface of each resin layer of the laminate Were integrated by thermocompression bonding.

(iv) Rolling

A rolling roller (roll diameter: 55 mm, roller rotation speed: 4 mmZsec) that can control the pressure between the rollers and set the pitch interval within a range of 5% increase / decrease was used. The laminate was rolled with a rolling roller at a temperature of 160 ° C. in a hot air oven.

By the rolling, the total thickness of the laminate was reduced from 680 m to 27.2 m, the rolling reduction was 96%, and the thickness was reduced to 1Z25 by rolling. (2) Evaluation of multilayer film

It was confirmed that the thickness of the laminated film portion in the obtained multilayer film tended to become thinner toward the center, and the disorder of the laminated arrangement of each layer was extremely small. It was also confirmed that there was little disturbance in the protective film.

[0049] [Example 6]

(1) Production of multilayer film

(i) Formation of laminate

Polycarbonate and polymethylpentene were used as materials for the thermoplastic resin film. Using a co-extruder, a two-layer film having a thickness of about 25 μm was obtained from each thermoplastic resin. The resulting two-layer film was laminated in layers of 80 layers, and 100 m thick polycarbonate (same as that used for the above-mentioned laminated film material) was further used as a protective layer on both outer sides. Arranged to obtain a laminate.

(ii) Pre-crimping

The laminated film was maintained for 30 seconds by applying a load of 5600 Pa at a temperature of 25 ° C. with a batch press to remove air remaining between the layers of the laminated film.

(iii) Thermocompression bonding

Maintain the press pressure of 5600 Pa in the pre-bonding, preheat the laminated film with an electric heater and keep it at 210 ° C for 20 minutes, and heat-bond the interface of each resin layer of the laminate. It was.

[0050] (iv) Press

Using a batch-type press, pressing was performed at a temperature of 210 ° C and a pressure of 19.4 MPa for 1 minute to obtain a multilayer body having a thickness of 194 m. Next, a protective layer with the thickness of 400 μm (same as the polycarbonate used for the first protective layer) is placed on both outer sides of the obtained multilayer body, and the same conditions as above (temperature and pressing pressure) A second press was performed to obtain a multilayer film with a thickness of 90 m.

In the first press, the total thickness of the laminate was reduced to 2200 μm force 194 μm, the reduction ratio was 91.2%, and the thickness was reduced to 1Z11.3 by the first rolling.

The second press reduces the thickness of the multilayer body and protective layer to 994 μm force to 151 μm and reduces The rate was 84.8%, which was further reduced to a thickness of 1Z6.6 by the second rolling.

In the second rolling, for the laminated film part, the thinned laminated film decreased from about 2.3 m (average thickness) to about 644 nm (average thickness) per layer, and the reduction ratio was 72%. Furthermore, the film thickness was reduced to 1Z3.6.

By the above two thin films, the thickness of each layer of the laminated film is reduced from about 25 m (average thickness) to about 644 nm (average thickness), and the thickness is reduced to 1 / 38.8. It was done.

(2) Evaluation of multilayer film

Figure 2 shows a cross-sectional photograph of the cross-sectional structure of the resulting multilayer film taken with a scanning electron microscope (SEM). It has been confirmed that the thickness of the laminated film tends to be thin in the central direction and the disorder of the laminated arrangement of each layer is extremely small.

[0051] [Example 7]

(1) Thermocompression bonding of laminates

(1) Formation of laminate

Using polystyrene and polymethylmethacrylate, each film is laminated with 26 layers each of 25 μm thickness, and both sides have 100 μm thick polystyrene (thermoplastic glass). The same resin as the polystyrene used for the fat film was disposed as a protective layer to obtain a laminate.

(ii) Pre-crimping and thermocompression bonding

The laminate was pre-pressed by using a batch type press at a temperature of 25 ° C. and maintaining a load of 3000 Pa for 4 seconds for 30 seconds to remove air remaining between the layers of the laminate. Maintaining a load of 3000 Pa in the pre-crimping, preheating the laminate from both sides with an electric heater and maintaining for 15 minutes after the center of the laminate reaches 160 ° C. Each resin layer of the laminate The interface was integrated by thermocompression bonding.

(2) Evaluation of laminates thermocompression bonded

Figure 3 shows the results of observation of the cross-sectional structure of the thermocompression-bonded laminate with a scanning electron microscope (SEM).

The interface of each layer was thermocompression bonded, and no turbulence or gas residue was observed between the layers.

[0052] [Example 8] (1) Thermocompression bonding of laminates

Using polystyrene and polymethylmetatalate, films with a thickness of 25 μm are laminated alternately to 70 layers, and 300 μm thick polystyrene (thermoplastic glass) is formed on both outer layers. The same resin as the polystyrene used for the fat film was disposed as a protective layer to obtain a laminate.

The laminate was pre-press-bonded with a batch press at a temperature of 25 ° C. and maintained at 30 ° C. for 30 seconds to remove air remaining between the layers of the laminate.

While maintaining the load of 5600 Pa in the pre-bonding, the laminate is preheated from both sides with an electric heater and maintained for 15 minutes after the center of the laminate reaches 160 ° C., and each resin layer of the laminate is maintained. The interface was integrated by thermocompression bonding.

(2) Evaluation of laminates thermocompression bonded

Fig. 4 shows the results of observation of the cross-sectional structure of the thermocompressed laminate with a scanning electron microscope (SEM).

[0053] [Comparative Example 1]

A multilayer film was produced by the first press in the same manner as described in Example 1 except that protective layers were not used on both outer side surfaces of the laminated film.

The cross-sectional structure of the obtained multilayer film was observed with an optical microscope or a scanning electron microscope (SEM). In the laminated film layer structure at the time of hot rolling when there is no protective layer on both sides, the outermost layer is disturbed because the laminated film is subjected to direct rolling stress compared to the case where the protective layer is present. In addition, it was confirmed with the naked eye that such a laminated film did not develop color and had low transparency and white turbidity.

[0054] [Comparative Examples 2, 3, and 4]

(1) Thermocompression bonding of laminates

(i) Preparation of laminate

The two-layer film prepared in Example 1 was alternately laminated so as to form 24 layers to obtain a laminated film. Next, a laminate in which a polystyrene protective layer having a thickness of 100 m was provided only on one outer surface of the laminated film was prepared. (ii) Pre-compression bonding, thermocompression bonding

In the pre-compression, pre-compression was performed with the press pressures in Comparative Examples 2, 3, and 4 being OP a, 170 Pa, and 1800 Pa at a temperature of 25 ° C., respectively. Each load in the pre-bonding is maintained, and both outer side forces are preheated by the electric heater and maintained for 20 minutes after the center of the laminate reaches 160 ° C. The interface was integrated by thermocompression bonding.

[0055] (2) Evaluation of thermocompression-bonded laminate

The cross sections of the laminates obtained in Comparative Examples 2, 3, and 4 were photographed with an optical microscope. The photographs are shown in FIGS. In Comparative Examples 2, 3, and 4, residual gas is observed between the layers of the laminate, and obvious disturbance is observed in a part of the layers of the laminate.

That is, in FIG. 5 of Comparative Example 2, gas remains in the right part between the 6th layer and the 7th layer below the protective layer (black portion), the 8th layer to the 9th layer, the 10th layer to the 11th layer, and Gas is left in the irregularly shaped parts between the 14th and 15th layers! /, And the resin penetrates when coated with a transparent epoxy resin when performing cross-section processing at the part (gray part) In gray.

The deformation of the lower right side seems to have been caused by thermal deformation due to residual gas during thermocompression. In Fig. 6 of Comparative Example 3, the thermocompression was not sufficiently advanced. As a result, a clear shift occurs at the interface of the laminated film.

In FIG. 7 of Comparative Example 4, gas (black portion) remains between the 10th to 11th layers below the protective layer. In addition, the gray portion existing between the 2nd to 3rd layers and the 10th to 11th layers is a portion where a thin crack occurs during the cross-section processing and the transparent epoxy resin used for the coating enters.

[0056] [Comparative Example 5]

(1) Thermocompression bonding of laminates

(i) Formation of laminate

A laminate was obtained in the same manner as described in Comparative Example 5.

(ii) Pre-crimping

Apply a load of 3600Pa at a temperature of 25 ° C to the laminate for 15 seconds using a batch press. By maintaining, it was pre-pressed to remove air remaining between the layers of the laminate.

(iii) Thermocompression bonding

Maintain the press pressure of 3600Pa in pre-crimping, preheat the laminate with electric heaters and maintain it for 15 minutes after the center of the laminate reaches 160 ° C. The interface of the resin layer was integrated by thermocompression bonding.

(2) Evaluation of laminates thermocompression bonded

Figure 8 shows the thermocompression-bonded laminate. It is confirmed that the layer is disturbed in the laminated part on the side where the protective layer is not provided. Once a layer has been disturbed, it has been difficult to eliminate the disorder of the layer no matter what conditions are selected in subsequent pressing or rolling.

[0057] [Example 9]

(1) Production of multilayer film

The following laminate was continuously subjected to preliminary pressure bonding, thermocompression bonding, rolling, and stretching to obtain a multilayer film.

(i) Formation of laminate

Co-extruded polystyrene and polymethylmetatalylate resin, each layer has a thickness of about 25 μm, and each layer is alternately laminated to form 70 layers. A 300 μm-thick polystyrene (the same resin as the polystyrene used for the thermoplastic resin film) was placed as a protective layer on both outer layer sides of the film to obtain a laminate. (ii) Pre-crimping

The laminate was pre-pressed by maintaining a load of 7200 Pa with a roller at a temperature of 25 ° C. for about 30 seconds to remove air remaining between the layers of the laminate.

(iii) Thermocompression bonding

In the hot air oven, the roller is preheated under a load of 7200 Pa by pre-bonding with a roller, and the center of the laminate reaches 160 ° C and is maintained for 15 minutes. Were integrated by thermocompression bonding.

[0058] (iv) Rolling

A rolling roller (roll diameter: 55 mm, roller rotation speed: 4 mmZsec) that can control the pressure between the rollers and set the pitch interval within a range of 5% increase / decrease was used. heat The laminate was rolled with a rolling roller at a temperature of 160 ° C. in a wind furnace.

By the rolling, the total thickness of the laminate was reduced from 2350 m to 106 m, the rolling reduction was 95.5%, and the thickness was reduced to 1Z22.2 by rolling.

At this time, for the laminated film portion in the laminated body, the thickness of the laminated film portion is 1750.

The / z m force was reduced to 24. The reduction ratio was 98.6%, and the film was thinned to a thickness of 1 / 71.4.

(V) Stretch

Next, the multilayer body rolled by the rolling roller was biaxially stretched by a tensile force by a chucking means. Stretching conditions were 120 ° C and stretched at a pulling speed of lOmmZmin.By the above stretching, the total thickness of the multilayer body was reduced to 106 m force to 46 m, the rolling reduction was 56.6%, and the stretching was 1Z2.3 Stretched to thickness.

At this time, for the laminated film part in the laminated body, the thickness of the laminated film part is reduced from 24.5 m force to 8.8 m, the rolling reduction is 64.1%, and it is stretched to the thickness of 1Z2.8. It was.

[0059] (vi) Reduction ratio due to rolling and stretching, etc.

As a result of the rolling and stretching, the total thickness of the laminate was reduced to 2350 m force and 46 m, so that the reduction ratio was 98.0%, and the film thickness was reduced to 1Z51.1.

At this time, the thickness of the laminated film part in the laminated body was reduced to 1750 / zm force and 8.8 m, so the rolling reduction was 99.5%, and the thickness of the thin film was 19.5%. It was.

(2) Evaluation of multilayer film

When the cross-sectional structure of the multilayer film obtained by the rolling and stretching is observed with a scanning electron microscope (SEM), the thickness of the laminated film existing between the protective films in the multilayer film tends to become thinner as it is directed toward the center. It was confirmed that there was very little disturbance in the stacking arrangement of each layer of the stacked film.

[0060] [Example 10]

(1) As shown in Fig. 9, assuming an image display sheet, draw two opposing electrode patterns. V Adjust the laminated film into the spacer in order to adjust the spacing between the support films. Multilayer film When placed as an optical element, when a voltage is applied to each of these electrodes from the power supply, an electric field is generated between the electrodes to confirm that the multilayer optical element (multilayer film) that is charged rotates. The following experiment was conducted.

When the multilayer optical element (multilayer film) rotates by such an applied voltage, display control on the image display sheet becomes possible by controlling the applied voltage.

(2) Fig. 9 shows that the silicone oil (which has almost the same specific gravity as the multilayer optical element) and the multilayer optical element are arranged in the spacer and are present on the inner surfaces facing each other. This is a conceptual diagram of an image display device that can rotate the multilayer film by applying an applied voltage to the electrodes. When the multilayer film is used as an actual optical display element, the size is considerably reduced. In Example 10, as a beaker scale experiment, an optical display element with an increased size was used.

[0061] (3) The multilayer film prepared in Example 1 was cut to a size of 3 mm x 3 mm, and bonded to one side of the same size epoxy resin to produce a multilayer film optical element.

The following confirmation experiment was conducted using the apparatus shown in FIG.

That is, in the spacer one that is set on the inter-electrode distance 10 mm, were placed silicone oil (viscosity ^{_{22mm 2 Zs eC (at25 ° C}} )) and the multilayer film optical element. In the multilayer optical element, different types of resin are bonded to one side, so that a charged layer is formed by charging due to a potential difference between the resins. When the applied voltage at both electrodes reached 700VZcm, the multilayer film rotated. It was also confirmed that the state after rotation was maintained after the voltage was released. The applied voltage in the above beaker experiment was 700 VZcm. When the display pixel size was set to the actual product level, the display pixel size was lmm to 100 μm, and the distance between the electrodes was 0.3 to Lmm from the above lcm. Therefore, the applied voltage is about 1 ~: LOVZcm.

Industrial applicability

[0062] The multilayer film of the present invention can be widely used for optical materials such as displays such as Nosocon, reflection films, and light interference coloring films, and the multilayer film optical element of the present invention can be used for electronic paper display particles (members). ).

Claims

The scope of the claims

[1] A laminated film (C) in which two types of transparent thermoplastic resin films (A, B) with different refractive indexes are alternately laminated in the thickness direction is used as two protective layers made of transparent thermoplastic resin (D) is a method for producing a multilayer film (Et) which is arranged between (D) to form a laminated body (E) and thin-films the laminated body (E) by pressing or rolling, and includes at least the following step (i) N, including (iii),

(i) Do not thermocompress the laminate (E)! Under the temperature condition, there will be no distortion or misalignment between the inner layers of the laminate (C) in the thickness direction from both outer sides of the laminate (E). Preliminary pressure bonding below the pressure is performed to remove the gas remaining between the laminated films (C) and between the laminated films (C) and the protective layer (D).

(iii) forming a thin film by pressing or rolling;

A method for producing a multilayer film.

[2] The method for producing a multilayer film according to [1], wherein the preliminary pressure bonding is performed at a pressure of 2500 Pa or more.

[3] The multilayer film production according to claim 1 or 2, wherein the pre-pressing is performed using a batch press or a rolling roller at 3000 Pa or more and half or less of the pressure during the pressing or rolling. Method.

[4] Preheating of the laminate (E) before or during the pre-compression, and gas remaining between the laminate films (C) and between the laminate film (C) and the protective layer (D) by pre-compression The method for producing a multilayer film according to any one of claims 1 to 3, wherein the removal is performed before reaching a temperature at which thermocompression bonding is possible.

[5] The temperature at which the thermocompression bonding is possible is as follows: (i) When the two types of thermoplastic resin films (A, B) are both amorphous resin, the center of the laminate (E) is 40-80 ° C higher than the glass transition temperature (Tg) of both types of thermoplastic resin

(ii) When one of the two types of thermoplastic resin films (A, B) is an amorphous resin and the other is a crystalline resin, the center of the laminate (E) is the two types of heat Low of plastic rosin 50 ° C. higher than the glass transition temperature (Tg) of the other, 30 ° C. below the melting point (Tm) of the crystalline resin from the temperature,

The method for producing a multilayer film according to claim 1, wherein the deviation is any one of claims 1 and 4.

[6] The method for producing a multilayer film according to any one of claims 1 to 5, wherein a difference in refractive index between the two types of thermoplastic resin films (A, B) is 0.05 or more. .

[7] A laminated film (C) formed by co-extrusion so that two types of transparent thermoplastic resin films (A, B) having different refractive indexes are laminated alternately in the thickness direction ( C1), or a laminated film (C2) in which a plurality of the laminated films (C1) are further laminated so as to be alternately laminated in the thickness direction. The manufacturing method of the multilayer film as described.

[8] The thickness of each thermoplastic resin film (A, B) in the laminated film (C) before pre-bonding is in the range of 5 to: L00 m, and the total number of layers of the laminated film (C) The method for producing a multilayer film according to any one of claims 1 to 7, wherein the thickness is 10 or more.

[9] The thickness of the two protective layers (D) in the laminate (E) before the pre-compression is 40 to 800 respectively.

The method for producing a multilayer film according to any one of claims 1 to 8, which is / zm and is not less than 0.04 times the thickness of the laminated film (C).

[10] The two types of thermoplastic resin films (A, B) in the laminate (E) and the glass transition temperature (Tg) of the resin used for the protective layer (D) are crystalline resin. 10. The range of 20 to 150 ° C in the case of a combination of amorphous fats, or the range of 50 to 120 ° C in the case of other combinations. The manufacturing method of the multilayer film as described in 1 ..

[11] The laminated film (C) in the laminated body (E) is thinned to a thickness of 1Z10 or 1Z90 by one press or rolling. A method for producing a multilayer film.

[12] A new protective layer (D) is provided on both outer side surfaces of the multilayer body obtained by thin-filming by pressing and further thinning by pressing is performed at least twice or by rolling. The thickness of the laminated film (C) part in the laminate (E) before pressing or rolling is thinned to 1Z20 to 1Z300 by rolling in multiple stages by combining a plurality of rollers. The manufacturing method of the multilayer film of any one of 1.

[13] The multi-layered body formed by thinning by one or more presses or one-stage or multi-stage rolling is further stretched by a tensile force, whereby lamination in the laminate (E) before pressing or rolling. 13. The method for producing a multilayer film according to claim 1, wherein the thickness of the film (C) part is reduced to 1Z150 to 1Z2000.

[14] The (0 pre-compression or GiO rolling is continuously performed by performing the (0 pre-compression, GO thermocompression bonding, and (m) i-stage or multi-stage rolling using a plurality of rollers. The method for producing a multilayer film according to any one of 1 to 13 above.

[15] (0) Pre-crimping, GO thermo-compression, and (m) i-stage or multi-stage rolling is performed using a plurality of roller means, and (iv) stretching by tensile force is performed. The method for producing a multilayer film according to any one of claims 1 to 14, wherein the stretching is continuously performed.

[16] A transparent film (C) in which two or more transparent thermoplastic resin films (A, B) with a refractive index difference of 0.05 or more are alternately laminated in the thickness direction is transparent. Two protective film (Dt) parts obtained by thinly forming a laminate (E) formed between two protective layers (D) made of various thermoplastic resins by pressing or rolling And a multilayer film (Et) composed of a multilayer film (Ct) portion located between the two protective films (Dt),

The total thickness of the laminated film (Ct) part is 500ηπ! A multilayer film whose thickness tends to decrease in the direction of the center at ˜100 m and in which the multilayer arrangement of the multilayer film (Ct) part is not disturbed.

[17] The multilayer film according to [16], wherein the multilayer film (Ct) portion is laminated by 20 to 500 layers in the thickness direction.

[18] The stacking accuracy ([(maximum layer thickness minimum layer thickness) Z minimum layer thickness] X 100 (%)) in the multilayer film (Ct) portion is 300% to 1500%. The multilayer film as described.

[19] The stack thickness ratio (the ratio between the maximum value and the minimum value of the resin layers having different stacking directions) in the stacked film portion (Ct) is a force ^ 25, according to any one of claims 16 to 18 The multilayer film described

[20] The reflectivity at a wavelength of red, blue, or green light is 60% or more.

9. The multilayer film according to 1 above, which is a deviation.

[21] Charging layers are provided on both sides of the multilayer film according to any one of claims 16 to 20.

A particulate multilayer optical element, wherein the multilayer optical element is housed between a pair of transparent electrodes, and can be controlled to rotate or move by application to the transparent electrodes. A multilayer optical element constituting a pixel of an image display device capable of displaying an image using reflection or transmission of light.

[22] The display of any one of red, green, blue, cyan, magenta, and yellow

The multilayer optical element according to 21.

[23] The multi-structure according to claim 21 or 22, which is a non-light-absorbing and interference-type optical structural color body that reflects light of any one color defined in claim 22 and transmits a complementary color to the color. Layer film optical element.

[24] The multilayer optical element according to any one of [21] to [23], wherein the maximum outer dimension is in the range of 2 μm to 200 μm.

25. The multilayer optical element according to claim 21, wherein the outer shape is a plane, cube, convex lens shape, or sphere.